Crystal Region Research Articles

Phase Equilibria of the Aqueous Quaternary System Li+, Rb+, Cs+//SO42–-H2O at T = 273.2 K

The phase equilibria of the quaternary system Li+, Rb+, Cs+//SO42–-H2O at T = 273.2 K was investigated by the isothermal dissolution method. The solubility and density of the system were measured and the related phase diagram, water content diagram, and density vs composition diagram were plotted. The solid phase of the quaternary invariant point was identified by the X-ray diffraction method and the solid solution morphology was analyzed by scanning electron microscopy. Results show that the stable phase diagram consists of 6 invariant points, 13 uninvariant curves, and 8 crystallization regions (corresponding to single salts Li2SO4·H2O, Rb2SO4, and Cs2SO4; double salts 3Li2SO4·Rb2SO4·2H2O, 3Li2SO4·Cs2SO4·2H2O, Li2SO4·Rb2SO4, and Li2SO4·Cs2SO4; and solid solution [(Rb, Cs)2SO4]). Also, the crystallization region of double salt 3Li2SO4·Rb2SO4·2H2O is the largest, which means that it is easiest to precipitate from this system. Meanwhile, rubidium and cesium easily form a solid solution in the sulfate system, which increases the difficulty of separating the two elements. Comparing the stable phase diagram of the ternary subsystems at T = 273.2 K and T = 298.2 K, it is found that the crystallization regions of Rb2SO4, Cs2SO4, [(Rb, Cs)2SO4], and 3Li2SO4·Cs2SO4·2H2O increase with the decrease of temperature, indicating that cooling is conducive to the crystallization of Rb2SO4, Cs2SO4, [(Rb, Cs)2SO4], and 3Li2SO4·Cs2SO4·2H2O.

Ion Addition by Electrolysis to Improve the Quantitative Analysis of Bacteria with MALDI-TOF MS

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is commonly applied to the identification of bacteria but rarely used for quantitative detection due to the inhomogeneous crystallization of the matrix leading to the unsatisfactory linear relationship between the sample amount and the mass spectrum signals. Herein, we proposed a noninterference ion addition (NIA) method by electrolysis to improve homogeneous crystallization during the evaporation progress of sample droplets on the target plates. The active metal wire was inserted in the droplet as the anode electrode, and metal ions were released through electrolysis. The directional migration of metal ions under the electric field can hinder the migration of matrix molecules to the boundary and homogenize the matrix crystals by forming spherical crystals. Simultaneously, trace cationic surfactant was added to the droplet for pinning the contact surface to define the circle crystallization region. The metal ions from the anode electrode wire were deposited on the surface of the target plates which served as the cathode. Therefore, ion addition has no interference effect on ionization during MALDI-MS detection. This NIA method benefits the homogeneous crystallization and so improves the quantitative analysis. NIA is suitable for biological samples with different matrices, and bacterial samples could be quantitatively analyzed.

Stable Phase Equilibria of the Quaternary System LiBr-NaBr-KBr-H2O and the Ternary System LiBr-KBr-H2O at 323.15 K

According to the composition characteristics of lithium, potassium, bromine, and other resources rich in the salt lake brine of the Qinghai–Tibet Plateau, the phase equilibria of the quaternary system LiBr-NaBr-KBr-H2O and its ternary subsystem LiBr-KBr-H2O at 323.15 K are studied by an isothermal dissolution equilibrium method. The solubility of each system in equilibrium solution at the corresponding temperature is measured, and the corresponding phase diagrams are drawn according to the phase equilibrium experimental data. The results show that there is no complex salt or solid solution in the ternary system LiBr-KBr-H2O at 323.15 K. The phase diagram contains one invariant point (E1), two univariate curves (AE1 and BE1), and two equilibrium solid crystallization regions (corresponding to LiBr·H2O and KBr), belonging to the simple cosaturated type. The quaternary system LiBr-NaBr-KBr-H2O also has no formation of complex salt and solid solution. The phase diagram contains two invariant points (F1 and F2), five univariate curves (E1F1, E3F1, F1F2, E2F2, and E4F2), and four equilibrium solid-phase crystallization regions (corresponding to LiBr·H2O, KBr, NaBr·2H2O, and NaBr). At the same time, to further explain the phase equilibrium relationship of each system at different temperatures and the change rule of each component, comparison and discussion are carried out.

Stable Phase Equilibria of Ternary Systems Li+,Rb+//SO4 2--H2O and Li+,Cs+//SO4 2--H2O at 273.2 K.

The stable phase equilibria of ternary systems Li+,Rb+//SO4 2--H2O and Li+,Cs+//SO4 2--H2O at 273.2 K are studied herein by the isothermal dissolution equilibrium method. The solubility and density of the systems are measured experimentally, and the related phase diagrams, density versus composition diagrams, are plotted. Results show that the ternary systems Li+,Rb+//SO4 2--H2O and Li+,Cs+//SO4 2--H2O are both complex systems with two kinds of double salts formed at 273.2 K. The stable phase diagrams of these two ternary systems all consist of one unsaturated solution region, three co-crystallization regions, three invariant points, four invariant curves, and four crystallization regions. By comparing the phase diagrams of the ternary system Li+,Rb+//SO4 2--H2O at 273.2 and 298.2 K, it is found that the crystallization regions of the two double salts (3Li2SO4·Rb2SO4·2H2O and Li2SO4·Rb2SO4) and the single salt Li2SO4·H2O all decrease, while that of Rb2SO4 increases when the temperature drops. Also, it can be seen from the phase diagram of the ternary system Li+,Cs+//SO4 2--H2O at 273.2 and 298.2 K that the crystallization regions of the double salt 3Li2SO4·Cs2SO4·2H2O and the single salt Cs2SO4 increase, while those of the double salt Li2SO4·Cs2SO4 and the single salt Li2SO4·H2O decrease as the temperature drops.

Solid–Liquid Phase Equilibria in the Quinary System NaCl-KCl-MgCl2-SrCl2-H2O at 273 K

To realize the comprehensive utilization of underground brines, this work focuses on the research of phase equilibria in salt–water systems containing potassium, sodium, magnesium, strontium, and chlorine. The solid–liquid phase equilibria in the quinary system NaCl-KCl-MgCl2-SrCl2-H2O at 273 K were determined by the isothermal dissolution equilibrium method. X-ray powder diffraction was used to identify the equilibrium solids in invariant points, and the XRD diffraction patterns of equilibrium solids in invariant points were obtained. Based on the experimental data, the three-dimensional equilibrium phase diagram was constructed. The results show that no solid solution is formed in the quinary system, while the double salt KCl·MgCl2·6H2O and corresponding hydrates SrCl2·6H2O and MgCl2·6H2O are formed. The three-dimensional equilibrium phase diagram of this quinary system at 273 K contains two invariant points, seven isothermal solubility curves, and five single salt crystallization regions corresponding to NaCl, KCl, MgCl2·6H2O, SrCl2·6H2O, and KCl·MgCl2·6H2O. In addition, two-dimensional projection phase diagrams with the saturated surfaces of NaCl, KCl, and SrCl2·6H2O were also analyzed, and the dry-salt phase diagrams were also obtained. When NaCl is saturated, there are two invariant points, five univariant curves, and four crystallization regions (KCl, MgCl2·6H2O, SrCl2·6H2O, and KCl·MgCl2·6H2O) in the dry-salt phase diagram. When KCl is saturated, the dry-salt phase diagram consists of only one invariant point, three univariant curves, and three crystallization regions (NaCl, SrCl2·6H2O, and KCl·MgCl2·6H2O). When SrCl2·6H2O is saturated, the dry-salt phase diagram contains two invariant points, five univariant curves, and four crystallization regions corresponding to NaCl, KCl, MgCl2·6H2O, and KCl·MgCl2·6H2O.

Immobilization of Arg-Gly-Asp peptides on silk fibroin via Gly-Ala-Gly-Ala-Gly-Ser sequences.

A simple method by which the functional peptide of Gly-Arg-Gly-Asp-Ser (GRGDS) is immobilized on the surface of silk fibroin (SF) films via Gly-Ala-Gly-Ala-Gly-Ser (GAGAGS) sequences is proposed. GAGAGS, a repeating amino acid sequence in the crystal region of Bombyx mori SF, performs a key role in interacting with and immobilizing SF molecules. Immobilization by this proposed method involves no chemical reaction, thereby preserving the original properties of the SF molecule. The density of GRGDS peptides existing on SF film was found to be higher in the GAGAGS-bound type than in the non-GAGAGS-bound type. Furthermore, results showed that the amount of immobilized (GAGAGS)GRGDS peptide increased as the β-sheet crystallization was promoted in the SF film. Fibroblasts, which adhered to the surface of the SF film, showed more extensibility because of the (GAGAGS)GRGDS immobilization, which suggests that the cell adhesion activity of RGD is functioning effectively.

Solid-Liquid Phase Equilibria of Quaternary System LiBr-NaBr-KBr-H2O and Its Subsystems at 348.15 K.

In view of the composition characteristics of lithium, calcium, and bromine rich in Nanyishan oilfield water of the Qaidam Basin, Qinghai Province, the phase equilibrium relationships of quaternary system LiBr-NaBr-KBr-H2O and its ternary subsystems LiBr-NaBr-H2O and LiBr-KBr-H2O at 348.15 K were studied by the isothermal solution equilibrium method, and the equilibrium solid-phase crystallization regions and composition of each invariant point in each system were determined. The results show that there is no complex salt or solid solution in ternary systems LiBr-NaBr-H2O and LiBr-KBr-H2O at 348.15 K, and the phase diagram contains only one invariant point, two isothermal univariate curves, and two equilibrium solid-phase crystallization regions. The quaternary system LiBr-NaBr-KBr-H2O also has no formation of complex salt or solid solution, and the phase diagram contains only one invariant point, three isothermal univariate curves, and three equilibrium solid-phase crystallization regions. Meanwhile, the phase equilibrium relationships and change laws of each component of the above-mentioned systems at different temperatures were compared and discussed.

Influence of composition and cooling rate of alumocalcium slag on its crumblability

The main components of metallurgical slags are iron compounds, which are extracted by reduction smelting. There are several types of this process with obtaining various products based on iron and slags of various compositions (aluminum-calcium self-disintegrating), etc. The mode of smelting and cooling of alumocalcium slag, formed during melting in the furnace, should ensure the most complete spontaneous crumbling of it, as well as high rates of extraction of REM from it. Synthetic slags similar in phase composition to industrial samples after smelting of iron-containing ores were selected for the experiments. The simulated samples correspond to the region of primary crystallization of bicalcium silicate on the triple state diagram of CaO – SiO2 – Al2O3 system. The slag after crumbling was subjected to a sieve analysis using a mechanical sieve. In the experiments, slags with a silicon module k = 2.0 were used, which actively crumbled during their cooling. With an increase in the silicon module, the crumbling deteriorates. It was established that it is impossible to precisely limit the areas of compositions of crumbling slags at certain cooling rates. The conducted studies showed that the crumblability of slags improves as it approaches the center of the bicalcium silicate region. The composition of slags close to composition of the intersection points of the lines 2CaO·SiO2 – 2CaO·Al2O3 and 2CaO·SiO2 – 12CaO·7Al2O3 with the lines of the permanent silicon module granulometric composition almost does not depend on the cooling rate. The temperature mode from smelting to cooling affects the slags crumblability. The most promising are slags with a silicon module in the range of 2.85 – 3.00, close to the phase triangle 12CaO·7Al2O3 – 2CaO·SiO2 – 2CaO·Al2O3 .

Crystal Growth of 3D Poly(ε-caprolactone) Based Bone Scaffolds and Its Effects on the Physical Properties and Cellular Interactions.

Extrusion additive manufacturing is widely used to fabricate polymer-based 3D bone scaffolds. However, the insight views of crystal growths, scaffold features and eventually cell-scaffold interactions are still unknown. In this work, melt and solvent extrusion additive manufacturing techniques are used to produce scaffolds considering highly analogous printing conditions. Results show that the scaffolds produced by these two techniques present distinct physiochemical properties, with melt-printed scaffolds showing stronger mechanical properties and solvent-printed scaffolds showing rougher surface, higher degradation rate, and faster stress relaxation. These differences are attributed to the two different crystal growth kinetics, temperature-induced crystallization (TIC) and strain-induced crystallization (SIC), forming large/integrated spherulite-like and a small/fragmented lamella-like crystal regions respectively. The stiffer substrate of melt-printed scaffolds contributes to higher ratio of nuclear Yes-associated protein (YAP) allocation, favoring cell proliferation and differentiation. Faster relaxation and degradation of solvent-printed scaffolds result in dynamic surface, contributing to an early-stage faster osteogenesis differentiation.

Effect of sodium dodecyl sulfate on shape‐memory properties of side‐chain crystalline hydrogel via micellar copolymerization

AbstractA chemical shape‐memory hydrogel containing crystalline structure is prepared via micellar copolymerization of hydrophilic monomer acrylamide (AM) and hydrophobic monomer octadecyl acrylate (C18) in a sodium dodecyl sulfate (SDS) solution. The influence of SDS on the shape‐memory behavior of hydrogel investigated by differential scanning calorimetry (DSC) and Temperature‐dependent X‐ray indicate that the melting and crystallization peaks derived from the thermal properties of C18 units is different from peaks corresponding to the pure SDS. In addition, the microstructure evolution information of hydrogels dose not change upon heating process, regardless of the presence or absence of SDS. Therefore, only the hydrophobic associations formed by C18 blocks play a decisive role in the shape memory function of hydrogel system. The difference between the transition process (from temporary shape to permanent shape) of hydrogel with and without SDS at different temperature is because that the hydrophobic region of side chain crystallization of SDS‐free hydrogel may escape the restriction of SDS and become more sensitive to temperature, they can preferentially return to their initial shape under the same time and temperature than SDS‐containing gels. Whether SDS exists only affect the speed of shape memory behavior, but not the microstructure evolution of hydrogel system.

Magnesio-lucchesiite from the Kowary vicinity, Karkonosze Mountains, SW Poland: the third occurrence worldwide

AbstractTwo tourmaline samples occurring in quartz veinlets, which cross-cut an amphibolite body at the Budniki camp near the Kowary town in the south-west part of the Karkonosze Mountains, SW Poland, were studied through microprobe and single crystal X-ray diffraction. Samples were extracted from core and rim regions of crystals with concentric zoning. Chemical and structural data revealed that the core tourmaline is characterised by a dravite–oxy-dravite composition, with the formula: X(Na0.82Ca0.07K0.01Sr0.01□0.09)Σ1Y(Mg1.73Fe2+0.81Fe3+0.41Ti0.04V0.01)Σ3Z(Al5.85Fe3+0.15)Σ6(TSi6O18)(BO3)3(OH)3W(OH0.50O0.50)Σ1 and unit cell parameters a = 15.97377(14) Å and c = 7.22644(7) Å. The rim part of the crystals has a magnesio-lucchesiite composition, described by the formula: X(Ca0.49Na0.41K0.04Sr0.02□0.04)Σ1Y(Mg1.87Fe2+0.95Ti0.15Fe3+0.02V0.02)Σ3Z(Al5.49Fe3+0.51)Σ6(BO3)3(TSi6O18)(OH)3W(O0.81F0.18OH0.01)Σ1 with unit cell parameters a = 15.9863(3) Å and c = 7.22426(15) Å. Both tourmalines show similar refined populations at the Y and Z sites: Y[(Fe2+0.810Mg0.680)Σ1.490(Al1.044Fe3+0.413V0.009)Σ1.465Ti0.045]Σ3Z(Al4.806Mg1.042Fe3+0.152)Σ6 (dravite–oxy-dravite), and Y[(Fe2+0.945Mg0.750)Σ1.695(Al0.737Fe3+0.404V0.018)Σ1.159Ti0.146]Σ3Z(Al4.749Mg1.115Fe3+0.137)Σ6 (magnesio-lucchesiite), with a comparable Mg/(Mg + Fe) ratio of ~0.54–0.56, oxidation of Fe expressed as Fe3+/Fetotal ratio ~0.36–0.41, and trace components such as Ti, Sr, V, Cr, Ni and Co. The geological history of the eastern Karkonosze region in the Kowary vicinity indicates that both tourmalines crystallised from B-bearing metamorphic fluids mobilised by Variscan prograde metamorphism from the protoliths of the Velká Upá mica schists that host the Budniki amphibolite. The fluids migrated into the tectonised amphibolite enriched in Ti, V, Cr, Ni and Co, and mineralised the fractures within it through deposition of soluble species in the form of quartz–tourmaline veinlets. Magnesio-lucchesiite crystallised in an early retrogression stage, probably from Ca- and F-bearing fluids secondary enriched in B by the dissolution of dravite–oxy-dravite. The Budniki camp is, in addition to the type and co-type magnesio-lucchesiite localities, the third documented occurrence of the species worldwide.

Photoluminescence microscopy as a noninvasive characterization method for defects in gallium oxide and aluminum gallium oxide epitaxial films

Herein we utilize polarized photoluminescence (PL) microscopy and spectral analysis to locate and characterize many different types of µm-scale extended defects present in melt-grown bulk crystals and metal-organic vapor-phase epitaxy (MOVPE)-grown epitaxial thin films of β-Ga2O3 and β-(Al,Ga)2O3. These include pits, divots, mounds, scratches, rotation domain boundaries, stacking faults, cracks, and other defect categories. Some types of µm-scale defects simply decrease overall PL yield, while others emit different spectra than single crystal regions. We combine PL microscopy with atomic force microscopy (AFM) and scanning electron microscopy (SEM) to provide detailed characteristics of these different types of features which can arise from both bulk crystal growth, surface preparation, and epitaxial growth processes. We show that sample quality (in terms of extended defects) can be determined by using PL and that attributing spectral features to isolated point defects is invalid unless the sample is proven to not contain extended defects.

An Analysis of Biologic Therapies in Patients With Asthma and Chronic Rhinosinusitis.

BackgroundAsthma, Allergic rhinitis (AR), Chronic Obstructive Pulmonary Disease (COPD), Eczema, and Chronic Rhinosinusitis with Sinonasal Polyposis (CRSwNP) are illnesses often characterized by type 2 (T2) inflammation, wherein T helper (Th) cells release pro-inflammatory cytokines such as IL (interleukin)-4, IL-5, IL-9, and IL-13. This response may also promote the production of IgE and an increase in/activation of serum eosinophils. In the aforementioned type 2 inflammatory diseases, this immune response can cause excess mucous production, inflammation of the airways, other atopic responses when patients are exposed to certain environmental allergic triggers. Relatively new biologic monoclonal antibody therapies such as dupilumab (blocks IL-4 and IL-13), benralizumab (blocks IL-5), mepolizumab (blocks IL-5), and omalizumab (blocks IgE Fc/fragment of crystallization region) offer novel therapeutic targets that more specifically and directly block type 2 inflammatory responses.MethodsTo examine the effect of monoclonal antibody biologic therapies on patient indicators of type 2 inflammation, a retrospective analysis of 193 patients on biologic therapy was conducted, and these patients were compared to 48 control patients with type 2 inflammatory diseases who did not initiate biologic therapy. Total Lund-MacKay radiographic score, FEV1 (forced expiratory volume in the first second), FEF25-75 (forced expiratory flow from 25-75% of the forced vital capacity curve), annualized pulmonary exacerbations, oral corticosteroid dose, and serum eosinophils were recorded at baseline (zero months), and at three, six, nine, and twelve months after initiation of biologic therapy. Least squares mean data and the percent change from the baseline of least squares mean for the biologic and control groups were compared.ResultsOmalizumab was the most common biologic therapy prescribed. Control patients were younger than patients who initiated biologic therapy. Patients on biologic therapy had statistically significant reductions in Lund-MacKay score, improvements in FEV1 and FEF25-75, reductions in serum IgE levels, and reductions in serum Eosinophils. Patients on biologic therapy also had statistically significant reductions in annualized pulmonary exacerbations and oral corticosteroid dose compared to controls.ConclusionsPatients with a variety of type 2 inflammatory conditions appear to have significant improvements in lung function, radiographic sinusitis, and serum markers of type 2 inflammation after initiation of biologic therapy versus controls. These therapeutic medications appear to significantly improve type 2 inflammatory disease course in patients who can tolerate these medications.

Numerical and experimental investigation of phase change characteristics and desalination effect of seawater freezing desalination in narrow channels

The crystallisation characteristics of freeze desalination in narrow channels need to be explored theoretically. Phase-field method (PFM) is an effective method for determining the microstructure during phase changes. In this study, the PFM coupled with the lattice Boltzmann method (LBM) was used to study the phase change behaviour and desalination effect of seawater freezing desalination in narrow channels. The phase, concentration, temperature, and flow fields were coupled and solved. A microscopy observation experimental system with a charge-coupled device camera was established to verify the numerical results. The salinity of the crystallisation zone was obtained by examining the crystallisation region. Important variables that could impact the desalination effect, such as the flow temperature, heat flux, and flow velocity, were investigated. The results showed that the flow temperature increased the desalting rate; the desalination ratio was 20 %–27.9 % in the temperature range of 263.15–283.15 K. The heat flux increased five-fold, and the desalination rate decreased from 22.6 % to 10.1 %. Owing to the counteracting effects of convection and solute diffusion on ice crystal growth, the inflow velocity had little effect on the desalination efficiency. The present method was expected to provide technical guidance for the device development of multistage crystallisers.

Reversible Stress‐Driven and Stress‐Free Two‐Way Shape Memory Effect in a Sol‐Gel Crosslinked Polycaprolactone

AbstractThe two‐way shape memory effect is the ability of a material to change its shape between two configurations upon application and removal of a stimulus, and, among shape memory polymers, it is featured only by few systems, such as semicrystalline networks. When studied under tensile conditions, it consists of elongation–contraction cycles along cooling and heating across the crystallization and melting region, typically under the application of a constant load. However, recent studies on crosslinked semicrystalline co‐polymers demonstrate that also a completely stress‐free, or self‐sustained, two‐way effect may be achieved through specific thermomechanical cycles. This effect is currently regarded with interest for the development of intrinsically reversible sensors and actuators, and it may also be displayed by simpler materials, as homopolymer‐based semicrystalline networks. Only seldom articles investigate this possibility, therefore in this work the two‐way shape memory behavior is studied on a poly(ɛ‐caprolactone) system, crosslinked by means of a sol‐gel approach. The effect is studied both under stress‐driven and stress‐free condition, by applying properly set‐up thermo‐mechanical histories. The results allow to describe the effect as a function of temperature, to reveal the dependence on specific testing parameters and to compare the extent of the reversible strain variation under these two conditions.

Thermal stability analysis of meta-aramid insulating paper based on computer molecular dynamics

A thermal stability analysis method of meta-aramid insulating paper based on computer molecular dynamics technology is designed in this paper. First, the raw materials and equipment for preparing meta-aramid insulating paper were determined to prepare meta-aramid insulating paper. Then, the internal structure and morphology of meta-aramid insulating paper are analyzed for the subsequent stability analysis. Finally, the basic principle of computer molecular dynamics technology is analyzed, which is used to analyze the thermal stability of meta-aramid insulating paper, mainly from the stability of its crystal region. The experimental results show that the proposed method is effective and feasible in analyzing the thermal stability of aramid insulating paper between samples.

Hydrothermal carbonization of sawdust with the bio-oil of same origin impacts evolution of structures of hydrochar

The high tendency towards polymerization is a bottle-neck issue in upgrading of bio-oil, which, however, is highly desirable in co-hydrothermal carbonization (HTC) of biomass with bio-oil for enhancing production of hydrochar. In this study, co-HTC of bio-oil of the same origin with poplar sawdust was conducted at 180 to 260 °C. The results showed that the HTC in a water medium containing 10% bio-oil could enhanced the yield of hydrochar by ca. 36% at 220 or 260 °C through the cross-polymerization of the sugar-derived furans and ketones/aldehydes as well as the phenolics in bio-oil with the sawdust-derived organics. Furans/sugars in bio-oil showed much more contribution to the increase of hydrochar yield than the phenolics like guaiacol. The highly reactive organics in bio-oil even could react with the crystal region of cellulose at 180 °C, and affected property of hydrochar at especially the higher temperatures by promoting deoxygenation, enhancing carbonization, eliminating polar functionalities like -OH, retaining C=O for continued polymerization, etc. The co-existence of aliphatic organics and phenolics in bio-oil renders the simultaneous formation of highly volatile fraction and aromatic structures in the hydrochar. These created the carbon-rich hydrochar with higher crystallinity, lower hydrophilicity and improved comprehensive combustion index.

Phase Equilibrium of the Ternary System Na2SO3–Na2SO4–H2O at 293.15, 313.15, and 353.15 K

The phase equilibrium data of the ternary system Na2SO3–Na2SO4–H2O at 293.15, 313.15, and 353.15 K were determined by the isothermal dissolution method. There are one invariant point, two univariant isothermal dissolution curves, and three crystallization regions at each temperature. As the temperature increases from 293.15 to 313.15 K, the solubilities of both Na2SO4 and Na2SO3 increase. The single crystallization region of Na2SO4 decreases, while the single crystallization region of Na2SO3 increases. When the temperature increases from 313.15 to 353.15 K, the solubilities of both Na2SO4 and Na2SO3 decrease. The single crystallization region of Na2SO4 decreases, and the single crystallization region of Na2SO3 is basically unchanged. Furthermore, based on the solubility data, the Pitzer ion interaction model was used to calculate the relevant Pitzer parameters and then to calculate the solubilities of Na2SO3 and Na2SO4 theoretically. The calculated Na2SO3 and Na2SO4 solubilities basically agree with the experimental values. The data obtained in this work have important implications for the design and optimization of the Na2SO3 crystallization process from resorcinol production wastewater.

Stress-Free Two-Way Shape Memory Effect of Poly(ethylene glycol)/Poly(ε-caprolactone) Semicrystalline Networks

In this work, poly(ethylene glycol) (PEG)/poly(ε-caprolactone) (PCL) semicrystalline networks were prepared by photo-cross-linking of methacrylated macromonomers with different molecular weights and in different proportions to obtain amphiphilic materials capable of displaying properly designed shape memory effects. Networks based on PCL 10 kDa and PEG 3 kDa showed suitable thermal and mechanical properties with well-separated crystallization and melting regions to achieve a self-standing two-way shape memory effect. Particularly, after the application of a specific thermomechanical history, these materials are capable of cyclically changing their shape between two configurations upon cooling–heating cycles in the absence of any external load applied. The effect of the composition of the networks and of the employed thermomechanical parameters, such as the applied strain and the actuation temperature, was investigated to shed light on the shape memory mechanism for this class of materials, which are considered promising for applications in the biomedical field and as reversible actuators for soft robotics.

DETERMINATION OF THE AREA OF CRYSTALLIZATION OF A NEW DOUBLE COMPOUND IN THE SYSTEM MONOMETHYLOL UREA-MOLYBDENUM PHYTO COMPOUND-WATER

The used seed protectants of agricultural crops, and in particular cotton, with a shortage of nitrogen fertilizers, do not provide plants with additional nitrogen in the required volume. In this article, the task is set to create an active and on its basis a perparativeform of a composition of multifunctional action, which allows simultaneously reducing diseases of cotton plants, increasing the accumulation of easily hydrolyzable nitrogen in the soil and obtaining a high yield of raw cotton.The purpose. Study of chemical interaction in a three-component water-salt system monomethylolourea (MMM) -molybdenum phytocomposition (FSMo) -water by visual-polythermal and isothermal methods. Objects. MMM, FSMo, double compound MMM•FSMo-active substance Results.The binary systems MMM–water and FSMo–water, which are part of the system under study, were studied from the complete freezing of thesystem -3.4÷45.4oC (MMM) and -1.3÷43.2oC (FSMo). The triple MMM–FSMo–water system was investigated at temperatures from -11.0 ÷40.0 oC, by six internal sections; of these, I-IV were carried out from the MMM–water side to the top of the molybdenum phytocomposition, and V-VI from the FSMo –water side to the top of the MMMformed in the temperature range -6.9÷35.2oC at a content of 3.7-38.3% MMM and 5.1-6.5% FSMo. Conclusion.Thus, by visual-polythermal and isothermal methods of physico-chemical analysis, the region of crystallization of a new double compound –an active substance based on monomethylolourea and a phyto-compound of molybdenum at a molar ratio of 1:1 has been established.