Publications by authors named "Cai Y Ma"

The particulate properties of α-lactose monohydrate (αLMH), an excipient and carrier for pharmaceuticals, is important for the design, formulation and performance of a wide range of drug products. Here an integrated multi-scale workflow provides a detailed molecular and inter-molecular (synthonic) analysis of its crystal morphology, surface chemistry and surface energy. Predicted morphologies are validated in 3D through X-ray diffraction (XCT) contrast tomography.

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  • This study focuses on using a morphological approach to measure how quickly facetted crystals grow in a solution, specifically looking at the β-form of l-glutamic acid.
  • The growth rates of various faces of the crystal were determined through image processing and were found to align with previous research using different methods.
  • The research also recorded a transformation in crystal shape from a needle-like appearance to a more tabular form, while providing a new method to estimate changes in solution supersaturation during the growth process.
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  • - The study explores how different solvents affect the crystallization and polymorphic forms of ritonavir, a drug used for treating AIDS, finding that rapid cooling leads to the unstable form I in certain solvents while ethanol favors the stable form II.
  • - Isothermal crystallization experiments indicate that higher solubility in specific solvents reduces the driving force required for nucleation, confirming a consistent pattern with theoretical predictions on solvation behavior.
  • - Molecular dynamics simulations reveal that solvent choice impacts conformational interactions in the solution phase, which may hinder nucleation and interfere with the formation of stable hydrogen bonds necessary for producing form II of the drug.
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Precision measurement of the growth rate of individual single crystal facets () represents an important component in the design of industrial crystallization processes. Current approaches for crystal growth measurement using optical microscopy are labor intensive and prone to error. An automated process using state-of-the-art computer vision and machine learning to segment and measure the crystal images is presented.

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Grid-based systematic search methods are used to investigate molecule-molecule, molecule-surface, and surface-surface contributions to interparticle interactions in order to identify the crystal faces that most strongly affect particle behavior during powder blend formulation and delivery processes. The model system comprises terbutaline sulfate (TBS) as an active pharmaceutical ingredient (API) and α-form lactose monohydrate (LMH). A combination of systematic molecular modeling and X-ray computed tomography (XCT) is used to determine not only the adhesive and cohesive interparticle energies but, also the agglomeration behavior during manufacturing and de-agglomeration behavior during delivery after inhalation.

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  • The study investigates how different solvents (isopropanol, ethanol, methanol, toluene, and acetonitrile) affect the solubility, crystallizability, and nucleation of tolfenamic acid (TFA) through experimental studies and intermolecular modeling.
  • Isopropanol shows the highest solubility for TFA, with strong solvent-solute interactions leading to greater than ideal solubility, while the crystallizability order varies across solvents, being lowest in isopropanol and highest in acetonitrile.
  • Nucleation occurs progressively in all solvents, with isopropanol exhibiting higher interfacial tension and larger critical nucleus radius, resulting in a lower nucleation rate
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The pharmaceutical compound entacapone (()-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)-,-diethylprop-2-enamide) is important in the treatment of Parkinson's disease, exhibiting interesting polymorphic behavior upon crystallization from solution. It consistently produces its stable form A with a uniform crystal size distribution on the surface of an Au(111) template while concomitantly forming its metastable form D within the same bulk solution. Molecular modeling using empirical atomistic force-fields reveals more complex molecular and intermolecular structures for form D compared to form A, with the crystal chemistry of both polymorphs being dominated by van der Waals and π-π stacking interactions with lower contributions (ca.

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TMEM151A, located at 11q13.2 and encoding transmembrane protein 151A, was recently reported as causative for autosomal dominant paroxysmal kinesigenic dyskinesia (PKD). Here, through comprehensive analysis of sporadic and familial cases, we expand the clinical and mutation spectrum of PKD.

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Intermolecular (synthonic) modelling is used for a statistical analysis of crystal lattice energies, together with their contributing intermolecular interactions for the crystallographic structures selected from the CCDC's Drug Subset (https://doi.org/10.1016/j.

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Recessive mutations in glutamate pyruvate transaminase 2 (GPT2) have recently been found to be associated with intellectual and developmental disability (IDD). In this study, we discovered a homozygous missense variant, NM_133443: [c.1172C > T, p.

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amino benzoic acid (PABA) has two well-characterised α- and β-polymorphic forms and, whilst both crystallise in the monoclinic space group 2/, they have quite different crystal chemistry and crystallisability behaviour. Previous work has shown that the molecular conformation deformation energy in the crystalline state is higher for the β-form than for the α-form and that the lattice energy for the former converges more slowly than for the latter overall. This suggests that not only is there a higher barrier to crystallisation for the β-form but also that low solution supersaturations might be needed for it to preferentially nucleate.

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Despite the clear benefits that nanotechnology can bring to various sectors of industry, there are serious concerns about the potential health risks associated with engineered nanomaterials (ENMs), intensified by the limited understanding of what makes ENMs toxic and how to make them safe. As the use of ENMs for commercial purposes and the number of workers/end-users being exposed to these materials on a daily basis increases, the need for assessing the potential adverse effects of multifarious ENMs in a time- and cost-effective manner becomes more apparent. One strategy to alleviate the problem of testing a large number and variety of ENMs in terms of their toxicological properties is through the development of computational models that decode the relationships between the physicochemical features of ENMs and their toxicity.

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The number of engineered nanomaterials (ENMs) being exploited commercially is growing rapidly, due to the novel properties they exhibit. Clearly, it is important to understand and minimize any risks to health or the environment posed by the presence of ENMs. Data-driven models that decode the relationships between the biological activities of ENMs and their physicochemical characteristics provide an attractive means of maximizing the value of scarce and expensive experimental data.

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Regulation for nanomaterials is urgently needed, and the drive to adopt an intelligent testing strategy is evident. Such a strategy will not only provide economic benefits but will also reduce moral and ethical concerns arising from animal testing. For regulatory purposes, such an approach is promoted by REACH, particularly the use of quantitative structure-activity relationships [(Q)SAR] as a tool for the categorisation of compounds according to their physicochemical and toxicological properties.

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Studies on the solid-state structure of two polymorphs of 4-methyl-2-nitroacetanilide (MNA) were conducted using magic-angle spinning (13)C, (15)N and (1)H NMR spectroscopy, together with first-principles computations of NMR shielding (including use of a program that takes explicit account of the translational symmetry inherent in crystalline structures). The effects on (13)C chemical shifts of side-chain rotations have been explored. Information derived from these studies was then incorporated within a systematic space-search methodology for elucidation of trial crystallographic structures from powder XRD.

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