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Trimethoprim (TMP) is a bacterial dihydroreductase inhibitor with broad-spectrum antibacterial properties. However, its oral absorption is limited by its low water solubility. Salification is one of the effective methods to solve this problem. This work proposes an efficient method for screening TMP salts using the conductor-like screening model for real solvents (COSMO-RS) model. 200 common compounds were introduced as candidates for screening. As a result, 39 hit compounds were subjected to experimental liquid-assisted grinding (LAG) with TMP, then 25 new solid phases were confirmed by PXRD. The solvent evaporation method was further used to acquire eight single crystals of TMP salts, whose structures were elucidated by single-crystal X-ray diffraction. Power X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and Fourier-transform infrared spectroscopy were employed to characterize seven of the TMP salts. Then, atoms-in-molecules was used to analyze intermolecular hydrogen bonding interactions in salts. Finally, we tested the equilibrium solubility and dissolution rate of the salt, which exhibited an increase in solubility. In a word, it is an effective screening method to obtain TMP salts combined with the COSMO-RS model and LAG method, which can be widely applied to other systems for screening of the target salts. [ABSTRACT FROM AUTHOR]

This study aimed to address the issue of the low solubility in the model drug probenecid (PRO) and its impact on bioavailability. Two salts of probenecid (PRO), 4-aminopyridine (4AMP), and 4-dimethylaminopyridine (4DAP) were synthesized and characterized by PXRD, DSC, TGA, FTIR, and SEM. The crystal structures of the two salts were determined by SCXRD, demonstrating that the two salts exhibited different hydrogen bond networks, stacking modes, and molecular conformations of PRO. The solubility of PRO and its salts in a phosphate-buffered solution (pH = 6.8) at 37 °C was determined, the results showed that the solubility of PRO salts increased to 142.83 and 7.75 times of the raw drug, respectively. Accelerated stability experiments (40 °C, 75% RH) showed that the salts had good phase stability over 8 weeks. Subsequently, Hirshfeld surface (HS), atom in molecules (AIM), and independent gradient model (IGM) were employed for the assessment of intermolecular interactions. The analyses of salt-forming sites and principles were conducted using molecular electrostatic potential surfaces (MEPs) and pKa rules. The lattice energy (EL) and hydration-free energy (EHF) of PRO and its salts were calculated, and the relationships between these parameters and melting points and the solubility changes were analyzed. [ABSTRACT FROM AUTHOR]

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) are toxic and carcinogenic compounds widely present in the natural environment, posing a serious threat to the environment and human health. However, the removal of OPAHs is mainly hindered by their low water solubility. Cyclodextrins (CDs) are frequently used to form inclusion complexes (ICs) with hydrophobic molecules to improve their solubility. In this study, we investigated the solubility enhancement ability of different CDs on 9-fluorenone, a common OPAH, through phase solubility experiments. We successfully prepared three solid ICs of 9-fluorenone with β-, hydroxypropyl-β-(HP-β-) and sulfobutylether-β-CD (SBE-β-CD) using the cooling crystallization method for the first time and characterized them via powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, etc. Molecular dynamics simulations were employed to investigate the binding modes and stable configurations of the ICs in the liquid phase and to explore the factors affecting their solubility enhancement ability. The results showed that all the CDs had a solubility enhancement effect on 9-fluorenone, with SBE-β-CD displaying the strongest effect, increasing the solubility of 9-fluorenone by 146 times. HP-β-CD, β-CD, α-CD, and γ-CD followed in decreasing order. Moreover, 9-fluorenone formed a ratio of 1:1 ICs to CDs. In addition, the interaction energy between SBE-β-CD and 9-fluorenone was the lowest among the CDs, which further validated the results of the phase solubility experiments from a theoretical perspective. Overall, this study provides a green method for the removal of 9-fluorenone pollutants in the environment and is expected to be applied to the removal and environmental remediation of other OPAHs. [ABSTRACT FROM AUTHOR]

In this work, solubility data of 1,5-pentanediamine adipate dihydrate in binary solvent systems of water + methanol, water + ethanol and water + N,N-dimethylformamide were experimentally measured via a static gravimetric method in the temperature range from 278.15 K to 313.15 K under atmospheric pressure. The results indicated that the solubility of 1,5-pentanediamine adipate dihydrate increased with the rising of temperature in all the selected binary solvent systems. For water + N,N-dimethylformamide, solubility increased as the mole fraction of water increased. However, the rising tendency changed when the temperature was higher than 303.15 K for water + methanol, and it would show a cosolvency phenomenon for water + ethanol. Furthermore, the solubility data were fitted with modified an Apelblat equation, NRTL model, combined nearly ideal binary solvent/Redlich Kister (CNIBS/R-K) model and Jouban–Acree model. The calculation results agreed well with the experimental data. Finally, the mixing thermodynamic properties of 1,5-pentanediamine adipate dihydrate in all tested solvents were calculated based on the experimental data and NRTL model. [ABSTRACT FROM AUTHOR]

Implanted medical devices that have poor friction property or biofilm formation can limit their service life and cause discomfort in patients. Recently, some zwitterionic coatings have been studied to modify the biomaterials surface for lubricating function, but the grafting methods of coatings are complicated and also seldom take the bacterial antiadhesion property into account at the same time. In our studies, motivated by the properties of nature mussels and human articular, we firstly successfully synthesized double adhesion protection of self-adhesive ternary polymer coating and achieved the excellent lubrication and antifouling functionalization of the medical devices surface. In details, the X-ray photoelectron spectroscopy, scanning electron microscope and the water contact angles could characterize the successful modification on the surface of titanium substrate. Additionally, the tribological tests carried out by atomic force microscope verified the ternary polymer could enhance the lubrication property owing to the hydration lubrication mechanism. Meanwhile, it also possessed the bacterial antiadhesion property for the initial 24 h attributed to the hydration repulsive force. We believe that, as a simple and universal preparation method, the ternary polymer could make a great significance for improving the surface function of biomaterials and alleviating patients' discomfort. [ABSTRACT FROM AUTHOR]

Solvates are important forms of crystalline materials and their formation and desolvation would affect the quality of the final products. In this work, to better understand the desolvation mechanism of solvates and its effect on the properties of the final products, cefathiamidine was selected as the model compound to investigate the influence of intermolecular interactions and the crystal structure on the desolvation process. Three new solvates and one reported solvate of cefathiamidine, including acetonitrile solvate monohydrate S1, acetone solvate monohydrate S2, n-propanol solvate 1.5 hydrate S3 and isopropanol solvate S4, were obtained by solution crystallization and their structures were determined by single crystal X-ray diffraction. The results indicated that the cefathiamidine molecule is highly conformationally flexible and eight conformations were observed in these solvates. The different solvates exhibit different intermolecular interactions, packing patterns and crystal stabilities. Furthermore, the desolvation processes of the solvates were systematically investigated by various analytical techniques and were analyzed based on the intermolecular interactions, molecular networks, void types, proportion of voids and packing patterns. The results showed that the desolvation of solvates S1 and S2 followed a cooperative–reorganization mechanism while the desolvation of solvate S3 and solvate S4 followed a destruction–reconstruction mechanism and a destruction–collapse mechanism, respectively. Finally, the corresponding mechanisms of the different solvates were proposed. [ABSTRACT FROM AUTHOR]

Two theoretical methods, self‐consistent Nývlt‐like approach and Sangwal's classical 3D nucleation theory‐based method, are employed to analyze the effects of additives (sodium sulfate) on the nucleation behavior of taurine. By correlating the measured metastable zone width of taurine containing different sodium sulfate concentrations, with saturation temperature and cooling rate, nucleation kinetic parameters in both two methods are determined. Fitting results demonstrate that higher sodium sulfate concentration results in the increase of solid–liquid interfacial energy γ, contrarily higher saturation temperature has the opposite effect thus changing of nucleation rate. The molecular modeling techniques are then applied to investigate the changes in the morphology of taurine which caused by the presence of sodium sulfate. Through molecular dynamic simulations, the interaction energy of sodium sulfate with taurine crystal faces are obviously larger than those of taurine and these differences on the (011) and (11‐1) are more significant than those on (021) and (111) faces. As a result, the growth of (011) and (11‐1) faces is inhibited and the morphology of taurine crystal is modified from needle to columnar. The influence of sodium sulfate on taurine studied in this work provides theoretical guidance for industrial production. [ABSTRACT FROM AUTHOR]

To investigate the effect of positional isomerism on cocrystallization and reveal the role of weak interactions in the formation of cocrystals, experimental characterization complemented with theoretical computations was thoroughly conducted by using p-hydroxybenzoic acid (PHBA), o-hydroxybenzoic acid (OHBA), m-hydroxybenzoic acid (MHBA) and malonic acid (MA) as model compounds. Selective formation of a new cocrystal was discovered between PHBA and MA molecules via several methods, while no cocrystal was formed between OHBA/MHBA and MA molecules. The PHBA–MA cocrystal was thoroughly characterized and analyzed through several solid characterization techniques such as powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) analysis, Fourier transform infrared (FTIR) spectroscopy, single crystal X-ray diffraction (SCXRD), etc. Taking advantage of a myriad of computational modelling techniques, the molecular recognition mechanism which drove the formation of cocrystals was comprehensively investigated and understood at a molecular level. The structural change accompanied by the cocrystal formation could be rationalized by FTIR spectroscopy and electron density variation analysis. Hirshfeld surface (HS) analysis indicated that O–H⋯O hydrogen bonds played a critical role in the formation of this cocrystal. Molecular electrostatic potential (MESP) surface analysis was employed to predict the interaction sites for cocrystallization, which were in good accordance with the experimental results. Moreover, possible reasons for the selective cocrystallization were analyzed and proposed. [ABSTRACT FROM AUTHOR]

The solubility data of sorbic acid in binary systems of (ethanol + water), (1-propanol + water) and (2-propanol + water) were measured from 283.15 to 323.15 K using the static equilibrium method under atmospheric pressure. It was found that the solubility of sorbic acid in the three binary solvent systems increased with increasing temperature as well as increasing initial mole fraction of organic solvent in these systems. The van't Hoff–Jouyban–Acree model, the modified Apelblat–Jouyban–Acree model and the CNIBS/R-K model were proposed for correlating the experimental solubility values in various solution systems. Furthermore, the dissolution thermodynamic properties of Gibbs energy change (ΔsolGo), molar enthalpy change (ΔsolHo) and molar entropy change (ΔsolSo) were calculated from the experimental solubility data, using the van't Hoff equation. The positive values of ΔsolGo, ΔsolHo and ΔsolSo indicate that these dissolution processes of sorbic acid in the solvents studied were all endothermic and entropically favorable. In addition, the change of dissolution enthalpy was the main contributor to the positive value of the molar Gibbs energy of the dissolution process. The experimental solubility and the models used in this work would be conducive to purifying sorbic acid from its crude mixtures. [ABSTRACT FROM AUTHOR]

In this work, the mechanism of solvent‐mediated desolvation transformation of lenvatinib mesylate (LM) was investigated. Two new solid forms of LM, a dimethyl sulfoxide (DMSO) solvate and an unsolvated form defined as form D, were discovered and characterized using powder X‐ray diffraction, thermogravimetric analysis, differential scanning calorimetry, polarized light microscopy and Raman spectroscopy. To investigate the thermodynamic mechanism of solvent‐mediated desolvation transformation (SMDT) from LM DMSO solvate to form D, solubilities of LM DMSO solvate and form D in binary solvent mixtures of DMSO and water at different water volume fractions and temperatures (293.15–323.15 K) were measured and correlated by non‐random two liquids model. The solubility data were used to evaluate the thermodynamic driving force of the SMDT process from DMSO solvate to form D and the effect of the activities of water and DMSO on the transformation process. Raman spectroscopy was used to monitor in situ the solid phase compositions during the SMDT process from LM DMSO solvate to form D while the solution concentration was measured by the gravimetric method. The overall desolvation transformation experiments demonstrated that the SMDT process was controlled by the nucleation and growth of form D. Moreover, effects of operating factors on the SMDT process were studied and the results illustrated that water activity in solution was the paramount parameter in the SMDT process. Finally, a new SMDT mechanism was suggested and discussed. [ABSTRACT FROM AUTHOR]

Crystal purity is of primary importance for pharmaceutical crystallization, and the inclusion of mother liquids inside the crystals poses a great challenge and threat to the product quality and purification efficiency. It is well recognized in industry that mother liquids can be included inside the crystals; however, the underlying formation mechanism remains poorly understood. Herein, we investigated the formation of liquid inclusions during crystallization of a model compound tetramethylpyrazine (TMP), which is a bioactive alkaloid drug, with an aim to better understand and hence control the liquid inclusions formed inside the crystals. The formation of mother liquid inclusions inside TMP crystals was fully characterized by optical polarizing microscopy, micro-Raman spectroscopy, and powder X-ray diffraction. Three types of fluid inclusions were observed in TMP crystals, and the single-phase liquid inclusions dominate. The effects of initial supersaturation and temperature on the formation of liquid inclusions were studied both qualitatively and quantitatively by optical microscopy and gas chromatography. It was found that high supersaturation and high temperature were favorable to the mother liquid inclusions in the resultant crystals. Moreover, the amounts of liquid inclusions inside the crystals are positively correlated with the growth rate of the TMP crystals. Solvent effects on the formation of liquid inclusions were also studied by choosing four types of solvents of distinct polarity. The results showed the solvent dependence of the formation of liquid inclusions, and the TMP crystals harvested from ethyl acetate displayed the most remarkable inclusions of mother liquids while the fewest liquid inclusions were found in isopropanol. Furthermore, the inclusion amounts of mother liquids can be correlated with the growth rates in different solvents but could not simply be correlated with only one type of property of the four solvents such as polarity, viscosity, dielectric constant, or surface tension. Finally, the inclusion of mother liquids inside TMP crystals was suggested to be effectively suppressed by crystallization at lower temperature and supersaturation, as well as in solvents with greater polarity and viscosity. [ABSTRACT FROM AUTHOR]

Batch crystallization in acidic aqueous solution of cephalexin was conducted by reactive crystallization with or without seeding. Supersaturation was generated by mixing ammonia and acidic aqueous solution of cephalexin and controlled by solution feeding rate and seeding conditions. UV and Morphologi G3 were used to measure supersaturation and aspect ratio. Experimental results demonstrated that burst nucleation occurred and the products were needle-like at high supersaturation; meanwhile, the products were plate-like and had high aspect ratio at low supersaturation. Analysis of the measured supersaturation profiles and corresponding aspect ratio explained the mechanisms governing the aspect ratio. The optimized operating parameters were also proposed (seeding supersaturation is equal to 1.3, seed mass ratio 8% and feeding rate 368 μL/min). [ABSTRACT FROM AUTHOR]

There has been much interest in the role of solution chemistry in determining the polymorphic formation of organic crystals. For convenience, the predominantly investigated systems are those that contain distinct building blocks among the polymorphs; in this work, an important drug excipient, D-mannitol (D-man), was selected as a case study, which represents a polymorphic system that only has the same building blocks. By employing the Hirshfeld surface analysis and molecular dynamics (MD) simulations, D-man's crystal packing and the solvation nature in different solvents were studied on the molecular level. The results suggest that there is a direct link between the solution speciation and crystal structure, and two distinct solvation modes were identified along with their impacts on nucleation. This study indicates the significant role of solvation in determining D-man's nucleation and offers new insights into the research on systems that do not have distinct building blocks among the polymorphs. [ABSTRACT FROM AUTHOR]

The solubility of N,N′-Bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine in seven pure solvents (acetonitrile, acetone, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and isobutyl acetate) and two binary solvent mixtures (acetone + acetonitrile and methyl acetate + acetonitrile) were measured from 273.15 to 303.15 K at atmospheric pressure by a dynamic method. The solubility data in these pure solvents were correlated by the modified Apelblat model, the Wilson model and the NRTL model, and that in the binary solvents mixture were fitted to the CNIBS/R-K model and the NRTL model. Furthermore, the mixing thermodynamic properties in pure and binary solvent systems were calculated and are discussed, based on the NRTL model. Finally, the applicability of the model of Zhang et al. (Ind Eng Chem Res 51:6933-6938, 2012) in correlating solubility data versus dielectric constant was extended from organic solvent-water mixtures to pure organic solvents and nonaqueous organic solvent mixtures. It was found that the dissolution behavior of a compound in the binary solvent mixtures can be predicted to some extent from those in pure solvents. [ABSTRACT FROM AUTHOR]

Crystals of a new organometallic nonlinear optical (NLO) compound, di-μ-chloro-bis[chlorotri(thiourea)bismuth(III)]-pentachloro(thiourea)bismuth-ate(III) (DCBPB), have been successfully grown from formic acid aqueous solutions of thiourea and bismuth chloride by a slow evaporation technique. The crystal structure and atomic composition of DCBPB have been confirmed by single crystal X-ray diffraction (SCXRD), Fourier transform infrared spectra, and elemental analysis. The SCXRD results proved that DCBPB crystallizes in triclinic space group P1 with unit cell dimensions of a = 7.0606(2) Å, b = 8.8106(4) Å, c = 16.3247(8) Å, α = 99.242(4)°, β = 95.309(3)°, γ  = 105.856(3)°, and Z = 2. DCBPB crystal exhibits excellent transmittance from 500 to 2500 nm and green fluorescence with maximum emission at 508 nm. The thermogravimetric-differential scanning calorimetry (TG-DSC) analysis indicates that a solid-phase reaction took place at 170.1 °C, whereas the decomposition temperature of the crystal material was 189 °C. The NLO property obtained by the Kurtz powder test showed that the second harmonic generation efficiency of DCBPB crystal is two-seventh of KDP crystal. [ABSTRACT FROM AUTHOR]

Abstract: The solvate and the solvent‐free form of sulfadiazine (SD) were investigated. SD was found to exist in one solvent‐free form and the N‐methylpyrrolidone (NMP) solvate form. The NMP solvate was shown to be a channel‐type compound. The intrinsic properties of the solvents were used to evaluate the effects of solubility on the phase transformation of SD and the NMP solvate. The SD phase could transform to the NMP solvate by NMP‐mediated phase transformation, which was governed by crystallization of the NMP solvate. The crystalline NMP solvate could transform to the solvent‐free solid state through solid‐solid transformation upon heating or water penetration‐mediated phase transformation. The rate of this water penetration‐mediated phase transformation of the NMP solvate to SD was unusually fast. It can be used to obtain SD aggregates of well‐defined shape and good powder properties. [ABSTRACT FROM AUTHOR]

Membrane distillation crystallization (MDC) is a promising hybrid separation process that has been applied to seawater desalination, brine treatment and wastewater recovery. In recent years, great progress has been made in MDC technologies including the promotion of nucleation and better control of crystallization and crystal size distribution. These advances are useful for the accurate control of the degree of supersaturation and for the control of the nucleation kinetic processes. This review focuses on the development of MDC process models and on crystallization control strategies. In addition, the most important innovative applications of MDC in the last five years in crystal engineering and pharmaceutical manufacturing are summarized. [ABSTRACT FROM AUTHOR]

The slurry transformation of sodium dehydroacetate monohydrate with different compositions of water and methanol was investigated. The water content and temperature did not only affect the solubility but also the crystal form of the precipitated material. A new needle hydrate form of sodium dehydroacetate appeared on the surface of the anhydrate when the water content was between 2 % and the critical transformation values which varied with temperature. The results revealed that the needle hydrate was a new form of sodium dehydroacetate monohydrate. A possible explanation for these observations was found in the relationship between the change of water content, the interaction between solute and solvent, and the influence of supersaturation. [ABSTRACT FROM AUTHOR]

We report here a unique method for the preparation of aggregated crystals with well-defined shape and size using a solvent penetration-mediated phase transformation. An unusually fast phase transformation of sulfadiazine was observed. The aggregated sulfadiazine crystals are obtained through a water penetration mediated transformation of sulfadiazine N-methyl pyrrolidone solvate. The aggregated particles keep the same shape and size of the parent crystals. [ABSTRACT FROM AUTHOR]

The Langdu skarn copper deposit in the Zhongdian area, Yunnan Province, China, has an average Cu grade of 6.49 %. The deposit is related to a porphyry intrusion (~216 Ma), which was emplaced in the Upper Triassic sedimentary rocks of the Tumugou and Qugasi Formations. At the Langdu skarn copper deposit, carbon and oxygen isotope ratios of fresh limestones (δO = 3.0-5.6 ‰ relative to V-SMOW; δC = 24.5-25.7 ‰ relative to PDB) and partly altered limestones (δO = 27-7.2 to −1.9 ‰; δC = 11.8-15.2 ‰) indicated that the deposit was a typical marine carbonate source. Oxygen and carbon isotope values for calcites formed at different hydrothermal stages are −9.1 to 0.2 and 10.1-16.3 ‰, respectively. Moreover, the carbon-oxygen isotopic composition of an ore-forming fluid (δO = 5.0-9.5 ‰, δC = −7.3 to −5.3 ‰) suggested the presence of magmatic water, which most likely came from the differentiation or melting of a homologous magma chamber. The deposition of Calcite I may arise from metasomatism in an open system with a progressively decreasing temperature. Later, the minerals chalcopyrite, pyrrhotite, quartz and Calcite II were precipitated due to immiscibility. Water-rock interaction could potentially be responsible for Calcite III precipitation in the post-ore stage. [ABSTRACT FROM AUTHOR]

The coarse crystal layer growth and liquid entrapment processes were investigated with gradient freeze technology in this paper. The research system was hemihydrate phosphoric acid (H3PO4·0.5H2O) crystal-phosphoric acid aqueous solution. The distribution coefficients of ions (Ca2+, Fe3+ and Na+) in this system were measured. The effect of supercooling degree gradient on layer growth and the effect layer growth rate on ions redistribution were studied. The result indicated that the layer growth rate increased with supercooling degree gradient as an exponential curve. The distribution coefficient tended to increase as an approximate 'S' curve when coarse crystal layer growth rate increased. The 'three region' theory was applied to explain this phenomenon. Each ion's diffusion parameter was obtained, which contributed to explain the separation differences between different ions. The work in this paper also indicated that layer crystallization was an effective separation technology for electronic grade phosphoric acid preparation. [ABSTRACT FROM AUTHOR]

This paper briefly describes the formation of ionic conductivity anomalies in soil cover, and the characteristics of ionic composition that forms conductivity anomalies, based on the theory of geoelectrochemical halo. Based on some practical results of soluble ions in soil cover and soil conductivity derived from a number of mining areas of both China and overseas, here we present the correlation of a conductivity anomaly with the ionic composition and establish a model for the formation of conductivity anomalies in soil cover. The results indicate that the formation of a conductivity anomaly is not a simple transformation of a secondary geochemical anomaly. A conductivity anomaly is formed as the result of electrochemical and chemical processes, by transformation of orebody into various ionic haloes through four physicochemical processes: 1) dissolution of the orebody, 2) migration of dissolved matter, 3) conversion of matter near the surface, and 4) the formation of ionic conductivity anomalies. The conductivity anomaly, as a physical parameter, essentially represents the integration of various geochemical compositions and is controlled by a set of particular ionic groups. [ABSTRACT FROM AUTHOR]

A version of the geoelectrochemical prospecting technique developed in China was demonstrated in China and Australia to test its suitability under both Chinese and Australian conditions. This paper briefly describes the mechanism and effectiveness of the technique applied to search of concealed mineralisation through regolith cover, based on both experimental and field tests. This paer deals with three main aspects of the method: a) how metallic ions are released from orebodies by electrochemical dissolution; b) how these ions migrate to the collector and are deposited as elements by electrochemical extraction in the presence of an electric field; and c) the effectiveness of the method illustrated by some case studies. [ABSTRACT FROM AUTHOR]

The article presents case studies related to paleovalley-related uranium from Australia and China. Topics discussed include types of Paleovalley-related uranium deposits including sandstone-hosted deposits and surficial deposits, geophysical and geochemical features of the paleovalleys, and association of uranium deposits with reduced lithologies.

Crystallization is one of the important unit operations for the separation and purification of solid products in the chemical, pharmaceutical, and pesticide industries, especially for realizing high-end, high-value solid products. The precise control of the solution crystallization process determines the polymorph, crystal shape, size, and size distribution of the crystal product, which is of great significance to improve product quality and production efficiency. In order to develop the crystallization process in a scientific method that is based on process parameters and data, process analysis technology (PAT) has become an important enabling platform. In this paper, we review the development of PAT in the field of crystallization in recent years. Based on the current research status of drug crystallization process control, the monitoring methods and control strategies of feedback control in the crystallization process were systematically summarized. The focus is on the application of model-free feedback control strategies based on the solution and solid information collected by various online monitoring equipment in product engineering, including improving particle size distribution, achieving polymorphic control, and improving purity. In this paper, the challenges of feedback control strategy in the crystallization process are also discussed, and the development trend of the feedback control strategy has been prospected. [ABSTRACT FROM AUTHOR]

This work could help to better understand the solvent effects on crystal habits and aspect ratio changes at the molecular level, which provide some guidance for solvent selection in industrial crystallization processes. With the catechol crystal habits acquired using both experimental and simulation methods in isopropanol, methyl acetate and ethyl acetate, solvent effects on crystal morphology were explored based on the modified attachment energy model. Firstly, morphologically dominant crystal faces were obtained with the predicted crystal habit in vacuum. Then, modified attachment energies were calculated by the molecular dynamics simulation to modify the crystal shapes in a real solvent environment, and the simulation results were in agreement with the experimental ones. Meanwhile, the surface properties such as roughness and the diffusion coefficient were introduced to analyze the solvent adsorption behaviors and the radial distribution function curves were generated to distinguish diverse types of interactions like hydrogen bonds and van der Waals forces. Results show that the catechol crystal habits were affected by the combination of the attachment energy, surface structures and molecular interaction types. Moreover, the changing aspect ratios of catechol crystals are closely related to the existence of hydrogen bonds which contribute to growth inhibition on specific faces. [ABSTRACT FROM AUTHOR]

This review presents a comprehensive crystallographic study of nicosulfuron solvates and their transformation. N,N‐dimethylformamide solvate and hydrate are prepared and characterized by single‐crystal X‐ray diffraction. Although the crystal systems are different, their space conformations are quite similar. Independent gradient model simulation reveals that the nicosulfuron dimer structure is dominated by dispersion energy and the solvent molecules combine with the solute molecules by electrostatic energy. Dynamic vapor sorption is used for observation of the gas‐phase‐mediated transformation from the N,N‐dimethylformamide solvate to the hydrate, which is found to be dominated by the diffusion of water molecules and desorption of N,N‐dimethylformamide molecules. [ABSTRACT FROM AUTHOR]

Many drugs have a propensity for agglomeration, resulting in poor flowability. Spherical crystallization can be used to improve product properties including flowability and particle size. In this work, two methods were developed and utilized to successfully make two kinds of azithromycin spherical particles, namely solid and hollow spheres. The resultant product exhibited regular spherical shape, large particle size, narrow particle size distribution and excellent flowability. The formation mechanism of these different spherical crystals was investigated with the help of a particle vision microscope (PVM). The immersion mechanism and the counter diffusion mechanism were proposed as the formation mechanisms for solid and hollow spheres, respectively. The effects of crystallization parameters on the spherical crystallization processes were investigated systematically. Furthermore, the tablet properties were evaluated to verify that the spherical particles obtained in this work can be directly used for tableting, thus avoiding granulation processes and reducing cost. [ABSTRACT FROM AUTHOR]

Removal of contaminants in wastewater, such as heavy metals, has become a severe problem in the world. Numerous technologies have been developed to deal with this problem. As an emerging technology, nanotechnology has been gaining increasing interest and many nanomaterials have been developed to remove heavy metals from polluted water, due to their excellent features resulting from the nanometer effect. In this work, novel nanomaterials, including carbon-based nanomaterials, zero-valent metal, metal-oxide based nanomaterials, and nanocomposites, and their applications for the removal of heavy metal ions from wastewater were systematically reviewed. Their efficiency, limitations, and advantages were compared and discussed. Furthermore, the promising perspective of nanomaterials in environmental applications was also discussed and potential directions for future work were suggested. [ABSTRACT FROM AUTHOR]