Isothermal Method Research Articles

A quantitative comparison between velocity dependent SIDM cross-sections constrained by the gravothermal and isothermal models

ABSTRACT One necessary step for probing the nature of self-interacting dark matter (SIDM) particles with astrophysical observations is to pin down any possible velocity dependence in the SIDM cross-section. Major challenges for achieving this goal include eliminating, or mitigating, the impact of the baryonic components and tidal effects within the dark matter halos of interest – the effects of these processes can be highly degenerate with those of dark matter self-interactions at small scales. In this work, we select 9 isolated galaxies and brightest cluster galaxies (BCGs) with baryonic components small enough such that the baryonic gravitational potentials do not significantly influence the halo gravothermal evolution processes. We then constrain the parameters of Rutherford and Møller scattering cross-section models with the measured rotation curves and stellar kinematics through the gravothermal fluid formalism and isothermal method. Cross-sections constrained by the two methods are consistent at $1\sigma$ confidence level, but the isothermal method prefers cross-sections greater than the gravothermal approach constraints by a factor of $\sim 3$.

Preparation of bainite phase microstructure by laser-electromagnetic induction hybrid solid-state phase transformation

Increasing the proportion of bainite and martensite phases is one of the effective ways to enhance the toughness of medium-carbon low-alloy steel(42CrMo). In this paper, the surface heat treatment of 42CrMo steel is carried out by using a laser heat source to achieve complete austenitization, then with electromagnetic induction heating for several times to implement insulation, and eventually to promote bainite phase transformation. In conjunction with the temperature history curves, OM, SEM, and EBSD are used to characterize the bainite morphology and percentage of bainite via different parameters of the hybrid process. The results demonstrate that the hybrid process combined with twice electromagnetic induction heating can yield a considerable proportion of bainite phase in 42CrMo steel. The resulting duplex structure, consisting of bainite and a minor fraction of martensite, exhibits a significant increase (81.1%) in tensile strength, while maintaining similar impact toughness. The elongation after fracture only has a slight reduction of 5.5% compared to that of the substrate. This innovative process provides a practical alternative to traditional bainite isothermal treatment method which must perform in a heat treatment furnace. Therefore, it is presented as a promising solution for enhancing the mechanical properties of medium-carbon low-alloy high strength steels.

Advances in plant pathogen detection: integrating recombinase polymerase amplification with CRISPR/Cas systems.

Plant pathogens are causing substantial economic losses and thus became a significant threat to global agriculture. Effective and timely detection methods are prerequisite for combating the damages caused by the plant pathogens. In the realm of plant pathogen detection, the isothermal amplification techniques, e.g., recombinase polymerase amplification (RPA) and loop-mediated isothermal amplification (LAMP), have emerged as a fast, precise, and most sensitive alternative to conventional PCR but they often comprise high rates of non-specific amplification and operational complexity. In recent advancements, clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated nuclease Cas systems, particularly Cas12, have emerged as powerful tools for highly sensitive, specific, and rapid pathogen detection. Exploiting the collateral activities of Cas12, which selectively cleaves single-stranded DNA (ssDNA), novel detection platforms have been developed. The mechanism employs the formation of a triple complex molecule comprising guide RNA, Cas12 enzyme, and the substrate target nucleotide sequence. Upon recognition of the target, Cas12 indiscriminately cleaves the DNA strand, leading to the release of fluorescence from the cleaved ssDNA reporter. Integration of isothermal amplification methods with CRISPR/Cas12 enables one-step detection assays, facilitating rapid pathogen identification within 30min at a single temperature. This integrated RPA-CRISPR/Cas12a approach eliminates the need for RNA extraction and cDNA conversion, allowing direct use of crude plant sap as a template. With an affordable fluorescence visualization system, this portable method achieves 100-fold greater sensitivity than conventional techniques. This review summarizes recent advances in RPA-CRISPR/Cas12a for detecting plant pathogens, covering primer design, field-level portability, and enhanced sensitivity.

I-motif sensor for the fluorometric detection of Monkeypox.

In this study, we developed an isothermal fluorometric diagnostic method for DNA virus-generating disorders such as Mpox. Our results showed that the release of a large number of protons during multiplex-LAMP markedly lowered the pH level, which transformed the retinoblastoma (Rb) linear ssDNA into i-motifs. Consequently, thiazole orange (TO; a fluorometric probe sensitive to the i-motif) boosted the signal-on fluorescence because of its ability to bind selectively to i-motifs. This multiplex-LAMP/i-motif-TO system enabled simultaneous detection aimed at numerous potential targets with remarkable sensitivity (1.47 pg per mL) and efficiency (30 minutes). Our method is expected to enable DNA-virus-related diseases to be efficiently and accurately assessed.

Multiplex competitive annealing mediated isothermal amplification with high fidelity DNA polymerase (HiFi-CAMP)

Various isothermal amplification methods have been developed for point-of-care testing (POCT) of various infectious diseases. Here, we proposed a novel isothermal amplification method, named as 5′-half complementary primers mediated isothermal amplification (HCPA). Because of the similarity of our method to the previous method competitive annealing mediated isothermal amplification (CAMP) in primer design, we also use the name CAMP for our method. We demonstrated that CAMP is mediated by both a linear isothermal amplification pattern and a loop-mediated isothermal amplification pattern. To improve the specificity and enable multiplex detection, we further developed HiFi-CAMP method that uses a small amount of high-fidelity DNA polymerase to cut HFman probe to release fluorescent signal. The HiFi-CAMP method was demonstrated to have a good specificity and sensitivity, and fast amplification speed in detection of three human respiratory viruses, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respiratory syncytial virus A (RSV-A) and influenza A viruses (IAV). When compared with gold standard RT-qPCR assays, the HiFi-CAMP assays showed sensitivities of 90.0 %, 71.4 % and 78.1 %, specificities of 100 %, 100 % and 95.5 %, and consistencies of 93.0 %, 93.3 % and 88.2 % for SARS-CoV-2, RSV-A and IAV, respectively. Furthermore, a duplex HiFi-CAMP assay was also developed to simultaneously detect RSV-A and SARS-CoV-2. The HiFi-CAMP will provide a promising candidate for POCT diagnosis in resource-limited settings.

Rapid Detection of Staphylococcus Epidermidis Using Electric-Double-Layer (EDL) Field-Effect Transistor (FET) Biosensors with Loop-Mediated Isothermal Amplification

Staphylococcus epidermidis is a Gram-positive bacterium which commonly grows in human skin, nasal passages, respiratory tract, intestinal tract, air, and water. Although it is harmless to healthy individuals, immunocompromised patients are at risk of infection, which can lead to severe symptoms. With the increased reliance on antibiotics in hospitals, the antimicrobial resistance of Staphylococcus epidermidis has also risen, pointing out a challenge in clinical treatment.Therefore, the diagnosis of this bacterium has gained significant attention. The aim of this experiment is to detect bloodstream infections (BSIs) in the shortest possible time. The study is intended to be implemented in hospitals to provide a more convenient method for medical professionals to conduct screenings. The approach involves screening for the most common disease sequence, ssDNA, followed by sequential detection of corresponding cDNA, plasmids, and bacteria. To detect bacteria with the least amount of bacteerial load, a novel isothermal amplification method called Loop-mediated isothermal amplification (LAMP) is employed to increase the concentration of DNA of BSIs bacteria before measurement. The overall time required for this process doesn’t exceed one day, significantly increasing speed for the detection of blood-borne bacteria in hospitals. The core mechanism of this platform involves the use of electric-double-layer-gated field-effect-transistors (EDL-gated FETs) to amplify the gate voltage changes generated when the ssDNA binds with complementary DNA. These voltage changes are then converted into numerical values for analysis and interpretation.Currently, the research results show that this biomedical sensor can detect concentrations ranging from 1fM to 1pM. With the assistance of LAMP, it has successfully achieved a concentration of approximately 1yM (10-24 M) and detected with EDL-gated FETs. The experiment was also carried out step by step on simulated clinical specimens. The experiments have found successful serum nucleic acid amplification methods that provide excellent detection limits. Compared with other biomedical sensors in the past, it not only has lower detection limits but also brings features such as faster, more convenient, and more portable.Keywords: EDL, FET, Staphylococcus epidermidis, Biosensor, LAMP Figure 1

Studies on in vivo antithrombotic activity of quercetin, a natural flavonoid isolated from a traditional medicinal plant, African eggplant (Solanum indicum)

Ethnopharmacological relevanceEvery year, cardiovascular diseases (CVDs) account for about 17.9 million deaths, making them the primary cause of both morbidity and mortality. Conventional drugs, which are often prescribed to treat cardiovascular diseases, are costly and have adverse effects. Consequently, dietary modifications and other medications are needed. Traditional use of Solanum indicum as cardiotonic to treat hypertension and anticoagulant potency has been reported but poorly evaluated scientifically. Aim of the studyThis study investigated the in vivo anticoagulant activity and mechanism of anticoagulation of quercetin (QC), a bioactive compound isolated from S. indicum (SI) hydroethanolic fruit extract. Materials and methodsBioassay-guided fractionation (anticoagulant activity) extracted QC from hydroethanolic SI extract. QC was extensively characterized biochemically and pharmacologically. The interaction between QC and thrombin was investigated using spectrofluorometric and isothermal calorimetric methods. Cytotoxicity, antiplatelet, and thrombolytic studies were carried out in vitro. The Swiss albino mice were used to assess the in vivo, anticoagulant, and antithrombotic activities of QC. ResultsQC exhibits anticoagulant activity via (i) uncompetitive inhibition of thrombin but not FXa with a Ki value of 33.11 ± 4.2 μM and (ii) a partial inhibition of thrombin-catalyzed platelet aggregation with an IC50 value of 13.2 ± 1.2 μM. The experimental validation of the in silico study's prediction of QC's binding to thrombin was confirmed by spectrofluorometric and isothermal calorimetric analyses. QC was nontoxic to mammalian, non-hemolytic cells and demonstrated thrombolytic activity by activating plasminogen. QC demonstrated in vivo anticoagulant efficacy, preventing k-carrageen-induced thrombus formation in mice's tails. In the acute circulatory stasis paradigm in mice, QC reduces thromboxane B2 (TXB2) and endothelin-1 (ET-1) while increasing nitric oxide synthase (eNOS) and 6-keto prostaglandin F1α (6-keto-PGF1 α). ConclusionEffective in vivo anticoagulant and antithrombotic properties of S. indicum's bioactive component QC point to the plant's potential use as a herbal anticoagulant medication for preventing and treating cardiovascular diseases linked to thrombosis.

EasyNAT Malaria: a simple, rapid method to detect Plasmodium species using cross-priming amplification technology.

This study established and validated EasyNAT Malaria Assay as a promising molecular detection tool for malaria screening of high-risk populations in clinical practice. This novel isothermal amplification method may effectively facilitate the rapid diagnosis of malaria and prevent its transmission.

Experimental and Modeling Study on Methane Hydrate Equilibrium Conditions in the Presence of Inorganic Salts.

The aim of this study was to determine the influence of four inorganic salts, KCl, NaCl, KBr and NaBr, on the thermodynamic conditions of methane hydrate formation. In order to achieve this, the vapor-liquid water-hydrate (VLWH) equilibrium conditions of methane (CH4) hydrate were measured in the temperature range of 274.15 K-282.15 K by the isothermal pressure search method. The results demonstrated that, in comparison with deionized water, the four inorganic salts exhibited a significant thermodynamic inhibition on CH4 hydrate. Furthermore, the inhibitory effect of Na+ on methane hydrate is more pronounced than that of K+, where there is no discernible difference between Cl- and Br-. The dissociation enthalpy (∆Hdiss) of CH4 hydrate in the four inorganic salt solutions is comparable to that of deionized water, indicating that the inorganic salt does not participate in the formation of hydrate crystals. The Chen-Guo hydrate model and N-NRTL-NRF activity model were employed to forecast the equilibrium conditions of CH4 hydrate in electrolyte solution. The absolute relative deviation (AARD) between the predicted and experimental values were 1.24%, 1.08%, 1.18% and 1.21%, respectively. The model demonstrated satisfactory universality and accuracy. This study presents a novel approach to elucidating the mechanism and model prediction of inorganic salt inhibition of hydrate.

Research on lifetime prediction method of FBGs with different reflectance based on thermal decay characterization

Based on the distinct thermal decay traits of high-reflectance FBGs (Reflectance = 98%) and low-reflectance FBGs (Reflectance = 10%), it's proposed that different grating strength characterizations be applied to predict their lifespan. Using isothermal and isochronous annealing methods to track high-temperature strength decay, we establish a master aging curve. This informs a temperature-specific time-dependent life prediction model for FBG strength. Experiments and simulations reveal that over 876,000 h at 37 °C, reflectance reduction was 1.07% for high-reflectance FBGs and 1.896% for low-reflectance FBGs, with NICC decreases of 0.0564 and 0.0995, respectively. Adopting NICC and reflectance as respective indicators for high-reflectance and low-reflectance FBGs refines the detection of minor intensity declines.

Experimental characterisation of the isosteric desorption energy of VeRCoRs concrete: Comparison of the isotherms and hygrometric methods

The Clausius-Clapeyron equation is an effective tool for describing the effect of temperature on water vapour adsorption isotherms in cementitious materials. The key information is the isosteric energy. This can currently be characterised experimentally using two approaches: (1) the isotherms method, which involves experimentally acquiring the desorption isotherm for two (or more) different temperatures, and (2) the hygrometric method, which involves monitoring the increase in vapour pressure at equilibrium with a small sample subjected to increasing temperature steps. It turns out that although each method has a fairly high uncertainty, the results obtained are similar. Finally, the results seem to suggest that the isosteric energy of Portland-based cementitious materials could be considered unique.

Mini-Program Enabled IoT Intelligent Molecular Diagnostic Device for Co-Detection and Spatiotemporal Mapping of Infectious Disease Pathogens.

Effective detection of infectious pathogens is crucial for disease prevention and control. We present an innovative Internet of Things (IoT) molecular diagnostic device featuring a WeChat mini-program for simultaneous detection and spatiotemporal mapping of respiratory pathogens. Leveraging social software's widespread usage, our device integrates seamlessly with WeChat, eliminating the need for app downloads and installations. Through a comprehensive detection system, including a user-friendly mini-program, a portable Point-of-Care fluorescence detector, and a diagnostic information management platform (EzDx Cloud), we demonstrate high sensitivity and specificity in detecting common respiratory viruses. Our SARS-CoV-2/H1N1 combo test kit, developed using a novel one-tube/one-step loop-mediated isothermal amplification-CRISPR method, shows remarkable performance. We address challenges in at-home nucleic acid testing by providing a cost-effective solution capable of detecting multiple pathogens simultaneously. Our system's versatility accommodates various assays operating at different temperatures and fluorescence intensities, offering significant advantages over traditional methods. Moreover, integration with EzDx Cloud facilitates disease monitoring and early warning systems, enhancing public health management. This study highlights the potential of our IoT molecular diagnostic device in revolutionizing infectious disease detection and control, with wide-ranging applications in both human and animal population.

The Phase Equilibria of Natural Gas Hydrate in the Presence of 1,3-Dimethylcyclohexane and Octyl-β-D-glucopyranoside.

The thermodynamic effect of octyl-β-D-glucopyranoside (OGP) on the formation of methane-1,3-dimethylcyclohexane (DMCH) hydrate was studied in this work. The thermodynamic equilibrium hydrate formation pressures between 275.15 K and 283.15 K were measured by the isothermal pressure search method. Different OGP aqueous solutions (0, 0.1, and 1 wt%) were used in this work. The experimental results show that OGP had no obvious thermodynamic inhibition on methane-DMCH hydrate formation when its concentration was low (0.1 wt%), whereas it had an inhibition on methane-DMCH hydrate formation when its concentration was high (1 wt%). The phase equilibrium hydrate formation pressure of the methane-DMCH-OGP system is about 0.1 MPa higher than that of the methane-DMCH system. The dissociation enthalpies of methane hydrate in different solutions remained uniform, which indicates that OGP was not involved in methane-DMCH hydrate formation. This phenomenon is explained from the perspective of the molecular structure of OGP. As a renewable and biological nonionic surfactant, the concentration of OGP in the liquid phase is low, so OGP can be added to the methane-DMCH system without significant thermodynamic inhibition.

Agricultural low-cost waste adsorption of methylene blue and modelling linear isotherm method versus nonlinear prediction

AbstractThis study shows that geographically marked wheat hull, named Siyez, rice hull Sarı Kılçık, and Taşköprü Garlic stalk were used as agricultural waste to potential adsorbent materials for removing methylene blue from aqueous solution. Experimental data were evaluated in both equilibrium batch process and kinetic studies. In addition, the factors that affect the adsorption capacities, such as pH solutions, methylene blue concentration, contact time, and temperatures, were also investigated. Obtained data were subject to two constant adsorption models of Langmuir, Freundlich, Temkin, and Dubinin−Radushkevich. The kinetic models (pseudo-first-order, pseudo-second-order, intra-particle diffusion and film diffusion) and thermodynamic parameters were evaluated. The adsorption isotherms, characterized by an excellent fit with the Langmuir model (R2 = 0.99) across all adsorbents, underscore the prevalence of monolayer adsorption of methylene blue, in contrast to the Freundlich equation. Adsorption kinetics of the methylene blue onto the adsorbents followed pseudo-second-order kinetic model. According to high regression coefficient (R2) and minimal values of nonlinear error functions like RMSE; the maximum monolayer adsorption capacities of wheat hull, rice hull and garlic stalk were found to be 62.50 (mg/g), 54.94 (mg/g), and 370.37 (mg/g), respectively. The results indicated that these proposed adsorbents could be low-cost and effective adsorbents for water purification and have adsorption capacity as much as comparable with the literature. In batch equilibrium studies, the adsorption of methylene blue dye onto the wheat hull, rice hull, and garlic stalk exhibited a significant correlation with temperature, contact time, and initial concentration of methylene blue dye and Adaptive Neuro-Fuzzy Inference System algorithm for forecasting overall the system parameter well fitted with these findings with the accuracy of outputs (R2 about 0.99 for each). Consequently, the thermodynamic analysis revealed that the adsorption process takes place in bulk diffusion by liquid phase mass transfer and occurred spontaneously with endothermically except garlic stalk. Adsorption thermodynamic studies show that the adsorption of methylene blue onto the garlic stalk was spontaneous and exothermic. Graphical Abstract

Desorption of humic monomers from Y zeolite: A high-temperature X-ray diffraction and thermogravimetric study

In this work, the thermal behaviour and kinetic modelling of p-hydroxybenzaldehyde (HBA) desorption was studied using both isothermal and non-isothermal methods from Y zeolite, to obtain a detailed structural and kinetic interpretation of the process. Rietveld refinement of in situ powder XRD patterns and TG analysis highlighted that the HBA thermal degradation occurred in the temperature range ∼530–750 K. This process significantly affects the geometry of the zeolite framework, thus causing a cooperative tilting of the tetrahedra and resulting in the deformation of both 6MRs and 12MRs rings. The HBA desorption experiment was also carried out in isothermal conditions at four different temperatures (473, 523, 623 and 673 K) which are selected on the basis of the relevant features from DTG/DTA curves. The value for the reaction order is nearly the same for all isothermal rates, providing strong confirmation of the validity of the reported apparent activation energy of the p-HBA decomposition process. The corresponding activation energy value (60.92 kJ/mol) agrees with literature data reported for dealuminated HZY (58 kJ/mol) and NaY.

Investigation on itraconazole solubility in aqueous solutions based on models, solvent effect, thermodynamic analysis and quantum chemical calculations

The mole-fraction solubility of itraconazole in four aqueous blends of ethanol/isopropanol/DMSO/methanol within the temperature range of 283.15 to 323.15 K was experimentally obtained using the isothermal shake-flask method. Under the identical temperature and ethanol/isopropanol/DMSO/methanol composition, itraconazole solubility in DMSO+water is much higher than that in ethanol/isopropanol/methanol + water. At the same temperature, the solubility increases monotonically with organic solvent concentration. X-ray power diffraction analysis demonstrated that over the course of the investigations, there was no crystal transition or solvate formation. The modified van’t Hoff-Jouyban-Acree and Jouyban-Acree models adequately related the solubility to solvent composition and temperature, with relative average deviations (RADs) not exceeding 7.65 %. Furthermore, the extended Hildebrand solubility approach was utilized to quantitatively characterize the solubility behavior at 298.15 K for the mixtures of ethanol/isopropanol/DMSO/methanol plus water. In both instances, the RADs were maintained below 4.12 %. The solubility parameter and dipolarity-polarizability of solutions have a major impact on the solubility fluctuation, as indicated by the analysis of the linear solvation energy relationship. The preferential solvation of itraconazole at 298.15 K was examined using the efficient approach of inverse Kirkwood-Buff integrals. The preferred solvation parameters showed positive values in blends within rich and moderate ethanol/isopropanol/DMSO/methanol composition regions. This suggests that the organic solvents preferentially solvated itraconazole. When itraconazole dissolved in the blends, thermodynamic analysis of the entropy-enthalpy compensation and dissolution parameters revealed both an endothermic and an enthalpy-driven mechanism. Furthermore, the microscopic electrostatic characteristics of basicity and acidity were effectively demonstrated by means of the electrostatic potential of molecular surface. The −C=O and −N=groups of the itraconazole molecule, which link the five-membered ring, are the primary targets of the electrophilic attack. An independent gradient model based on Hirshfeld partition analysis was used to demonstrate the weak interactions between itraconazole and solvents.

SERS biosensors based on catalytic hairpin self-assembly and hybridization chain reaction cascade signal amplification strategies for ultrasensitive microRNA-21 detection.

A highly sensitive surface-enhanced Raman scattering (SERS) biosensor has been developedfor the detection of microRNA-21 (miR-21) using an isothermal enzyme-free cascade amplification method involving catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR). The CHA reaction is triggered by the target miR-21, which causes hairpin DNA (C1 and C2) to self-assemble into CHA products. After AgNPs@Capture captures the resulting CHA product, the HCR reaction is started, forming long-stranded DNA on the surface of AgNPs. A strong SERS signal is generated due to the presence of a large amount of the Raman reporter methylene blue (MB) in the vicinity of the SERS "hot spot" on the surface of AgNPs. The monitoring of the SERS signal changes of MB allows for the highly sensitive and specific detection of miR-21. In optimal conditions, the biosensor exhibits a satisfactory linear range and a low detection limit for miR-21 of 42.3 fM. Additionally, this SERS biosensor shows outstanding selectivity and reproducibility. The application of this methodology to clinical blood samples allows for the differentiation of cancer patients from healthy controls. As a result, the CHA-HCR amplification strategy used in this SERS biosensor could be a useful tool for miRNA detection and early cancer screening.

Traditional to technological advancements in Ganoderma detection methods in oil palm.

Ganoderma sp., the fungal agent causing basal stem rot (BSR), poses a severe threat to global oil palm production. Alarming increases in BSR occurrences within oil palm growing zones are attributed to varying effectiveness in its current management strategies. Asymptomatic progression of the disease and the continuous monoculture of oil palm pose challenges for prompt and effective management. Therefore, the development of precise, early, and timely detection techniques is crucial for successful BSR management. Conventional methods such as visual assessments, culture-based assays, and biochemical and physiological approaches prove time-consuming and lack specificity. Serological-based diagnostic methods, unsuitable for fungal diagnostics due to low sensitivity, assay affinity, cross-contamination which further underscores the need for improved techniques. Molecular PCR-based assays, utilizing universal, genus-specific, and species-specific primers, along with functional primers, can overcome the limitations of conventional and serological methods in fungal diagnostics. Recent advancements, including real-time PCR, biosensors, and isothermal amplification methods, facilitate accurate, specific, and sensitive Ganoderma detection. Comparative whole genomic analysis enables high-resolution discrimination of Ganoderma at the strain level. Additionally, omics tools such as transcriptomics, proteomics, and metabolomics can identify potential biomarkers for early detection of Ganoderma infection. Innovative on-field diagnostic techniques, including remote methods like volatile organic compounds profiling, tomography, hyperspectral and multispectral imaging, terrestrial laser scanning, and Red-Green-Blue cameras, contribute to a comprehensive diagnostic approach. Ultimately, the development of point-of-care, early, and cost-effective diagnostic techniques accessible to farmers is vital for the timely management of BSR in oil palm plantations.

Solid-Liquid Phase Equilibria of the Pb2+, Ca2+, Mg2+//Cl--H2O Quaternary System and Its Subsystems at 303.2 K.

The solid-liquid phase equilibria of the ternary systems Pb2+, Ca2+//Cl--H2O, Pb2+, Mg2+//Cl--H2O, and Ca2+, Mg2+//Cl--H2O were investigated at atmospheric pressure and T = 303.2 K using the isothermal dissolution equilibrium method. Additionally, solid phase equilibria of the quaternary system Pb2+, Mg2+, and Ca2+//Cl--H2O were determined, and the corresponding stable phase diagrams and density-composition diagrams were constructed. The results indicate that the phase diagrams of Pb2+, Ca2+//Cl--H2O mainly consist of a ternary invariant point, two solubility curves, and four crystalline regions, while there are two ternary invariant points, three solubility curves, and six crystalline regions in the Pb2+, Mg2+//Cl--H2O and Ca2+, Mg2+//Cl--H2O systems. The results of the density-versus-w(CaCl2) plots of the various ternary systems confirm that the density of the equilibrium solution tends to go upward with the increase in the mass fraction of CaCl2. The density of various ternary systems reaches the maximum and equilibrium at the corresponding invariant point, and there is no significant change with the further increase in the CaCl2 mass fraction. Furthermore, the phase diagram of the Pb2+, Mg2+, Ca2+//Cl--H2O quaternary system includes two invariant points, five isothermal dissolution curves, and five crystalline regions. The order of the relative areas of the crystalline regions for the five salts is PbCl2 > CaCl2·2MgCl2·12H2O > 2PbCl2·3MgCl2·18H2O > MgCl2·6H2O > CaCl2·4H2O.

Solubility measurement, calculation, solvent effect and preferential solvation of fenoxaprop-p-ethyl in four cosolvent mixtures at (278.15–323.15) K

Equilibrium solubility of fenoxaprop-p-ethyl in aqueous mixtures of ethanol/ isopropanol/acetonitrile/N,N-dimethylformamide (DMF) plus water was experimentally measured by isothermal saturation method at (278.15–323.15) K under 101.2 kPa. The order of solubility (mole fraction) of fenoxaprop-p-ethyl in pure solvents from high to low is 4.233 × 10−2 (DMF 323.15 K) > 2.044 × 10−2 (acetonitrile 323.15 K) > 7.727 × 10−3 (isopropanol 323.15 K) > 5.338 × 10−3 (ethanol 323.15 K) > 2.565 × 10−5 (water 323.15 K). Experimental results showed that temperature and type of solvent were decisive factors for the dissolution of fenoxaprop-p-ethyl. The content of fenoxaprop-p-ethyl in solution was analyzed by high-performance liquid chromatography (HPLC). Moreover, the solubility data of fenoxaprop-p-ethyl was correlated by Jouyban-Acree (J-A) model, van’t Hoff-Jouyban-Acree (V-J-A) model and Apelblat-Jouyban-Acree (A-J-A) model. The maximum of root-mean-square deviation (RMSD), relative average deviation (RAD) and standard deviation (SD) predicted via three thermodynamic models were 1.78 × 10−4 (DMF + water), 2.87 × 10−2 (acetonitrile + water) and 1.79 × 10−4 (DMF + water), respectively. In addition, the solvent effect between solute and solvent molecules was deduced by KAT-LSER model and the result showed that dipolarity/polarizability interactions between the solute and solvent molecules were dominant in the dissolution of fenoxaprop-p-ethyl. Finally, the preferential solvation parameter (δx1,3) of fenoxaprop-p-ethyl was obtained by the method of inverse Kirkwood–Buff integrals and the preferential dissolution behavior of each concentration range is explained by Lewis acid base theory. However, for acetonitrile + water, the change of δx1,3 may be due to the polarization effects and it is not suitable for Lewis acid base theory.