The use of in situ tools to monitor the transformation of a polymorphic material has the potential to provide unique information about the mechanism and rate of transformation of the polymorphs. In this paper, the solution mediated transformation between α and β form p-aminobenzoic acid (PABA) was investigated in detail. Solubility of α and β form PABA in pure ethanol was also reported for the first time, allowing the accurate determination of the transition temperature of 13.8 °C. For the transformation experiments, Raman spectroscopy and Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy were used to in situ monitor the solid phase concentration and liquid concentration, respectively; Focused Beam Reflectance Measurement (FBRM) was used to in situ track the changes in the size and morphology of the particles. The observed changes were confirmed using PVM in-process imaging. It was proved by solubility data and transformation experiments that the relationship between α and β form is enantiotropic.

d-Mannitol is a typical polymorphic crystalline compound. In this paper, this polymorphic transformation from the α to the β form of mannitol is monitored by in situ Raman spectroscopy, focused beam reflectance measurement (FBRM) and particle vision measurement (PVM). The standard Raman spectra of the two polymorphs of mannitol were determined and the characteristic peaks for the different polymorphs were chosen to track the transformation process. By combining Raman with FBRM and PVM, relationships between fine particles and metastable form dissolution and also between coarse particles and stable form crystallization could be defined. The solution-mediated polymorphic transformation mechanism was confirmed by these in situ tools. The effect of temperature, solvent and substrate mass on the transformation time was also investigated. It was noted that operating temperature and solvent composition have a significant influence on the transformation time.

In this study, a molecular design method was used to select solvents for extractive distillation. A COSMO-SAC model was used to screen for prospective solvents from a wide variety of ionic liquids for extractive distillation. Based on the COSMO-SAC model, the r-profile database of ILs was established. Selectivity and solubility were used as the indexes for solvent screening. According to the molecular design method, three suitable extractive distillation solvents were determined for acetonitrile-water and ethanol-cyclohexane systems. Vapor -liquid equilibrium experiment were used to test chosen ILs. This study showed that the experimental and design results were consistent with each other. Therefore, this method is effective and applicable to pick ILs solvents for extractive distillation, and the results could provide a theoretical foundation for industrial production.

Raman spectroscopy is one of a number of potential in situ process analysis technologies (PATs) for application in crystallization processes. In this paper, the use of Raman spectroscopy in the cooling crystallization of mannitol is investigated. Mannitol has three known polymorphs (r, β, and δ) that can be assessed using Raman spectroscopy. Although several multivariate spectroscopic methods for measuring both the dissolved concentration and the polymorphic form using Raman exist, their application requires significant calibration and/or that several assumptions be made about the relationship between the concentration and the Raman spectra. In this paper, a novel and simple calibration-free univariate method for monitoring supersaturation during the cooling crystallization of mannitol is demonstrated. The use of the method to successfully monitor the transformation process of the metastable r form to the stable β form in aqueous solution is also presented.

The spontaneous nucleation of d-mannitol polymorphs at different initial concentrations in an aqueous solution was investigated. Two in situ process analytical technology (PAT) tools, Raman spectroscopy and focused beam reflectance measurement (FBRM), were combined to monitor the process, allowing instantaneous detection of polymorphs after nucleation. It was found that the stable β form of mannitol was favored at low initial concentrations, whereas the metastable α form nucleated at high concentrations and the metastable δ polymorph crystallized when the concentration was in the medium level. To help understand this phenomenon, the thermodynamic and kinetic characteristics of different polymorphs were analyzed. The solubility of the two metastable forms was determined by an innovative method with the aid of Raman spectroscopy, whereas the interfacial energy between polymorphs and the bulk solution were obtained from the induction time measurements. Consequently, the critical excess free energy and other critical parameters associated with the nucleation of various polymorphs were calculated. It was concluded that the nucleation of mannitol polymorphs from an aqueous solution depends on both the thermodynamic and kinetic properties, with the importance of each highly dependent on the supersaturation prevailing in the system.

Replacing petrochemical polymers with biomaterials for biodegradable mulch applications has attracted widespread attention. However, improving film performance and reducing costs remain an issue. In this work, we found that the synergistic effect of sodium alginate and quaternary lignin significantly improved the performance and reduced the cost of poly(vinyl alcohol) films. The water retention, ultraviolet (UV) resistance, heat collection, light transmission, mechanical properties, soil consolidation, and the degradation rates of the composite films were systematically studied. We found that the addition of lignin enabled the film to achieve complete UV resistance, while the sodium alginate synergistically improved the mechanical and water-holding properties of the film. The film improved soil slumping, and the water vapor permeability of the film was 109.2 g•m −2 •day −1 . The degradation of the film was facilitated by the self-degradation properties of sodium alginate and lignin, which degraded 55% after 50 days.

As there appeared to be no data available on Toxocara canis infection in the children of Swaziland, a serological survey of T. canis infection was recently conducted among 92 children aged 3-12 years from rural slums in the low- and middle-veld. A child was considered seropositive if, in western blots based on the excretory-secretory antigens of larval T. canis, his or her serum gave a positive result when diluted 1 : 64. Forty-one (44.6%) of the children were found seropositive. There were no statistically significant differences in seroprevalence between the 49 boys and 43 girls investigated (46.9% v. 41.8%) or between the eight subjects aged 12 years and the 47 aged < or = 5 years (62.5% v. 38.3%); the corresponding odds ratios were 0.81 (95% confidence interval=0.36-1.86; P=0.62) and 2.69 (95% confidence interval=0.57-12.62; P=0.20), respectively. The 66 subjects from the middleveld were, however, significantly more likely to be seropositive than the 26 subjects from the lowveld (54.5% v. 19.2%; odds ratio=5.04, with a 95% confidence interval of 1.70-14.98; P<0.01). It seems likely that T. canis infection is common among the children who live in slums in Swaziland, particularly in the country's middleveld, probably as the result of poor hygiene and poor sanitation.

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