116 results found
Spathi C, Young N, Heng JYY, et al., 2014, A simple method for preparing super-hydrophobic powder from paper sludge ash, Materials Letters, Vol: 142, Pages: 80-83, ISSN: 1873-4979
Paper sludge ash (PSA) is a readily available waste material generated by the paper recycling industry. This work reports on the production of hydrophobic powders by dry milling PSA in the presence of a fatty acid surface functionalising agent. Optimum laboratory processing involves dry milling for 8 h with a 4 wt.% addition of stearic acid and this produced a super-hydrophobic powder with a water contact angle of 153°. Different chain length fatty acids were investigated but stearic acid produced the highest hydrophobicity. The super-hydrophobicity of PSA results from the micro-particulate texture induced by dry milling with simultaneous formation of calcium stearate self-assembling surface monolayers chemically bonded to fracture surfaces.
Shah UV, Olusanmi D, Narang AS, et al., 2014, Decoupling the contribution of dispersive and acid-base components of surface energy on the cohesion of pharmaceutical powders, International Journal of Pharmaceutics, Vol: 475, Pages: 592-596, ISSN: 1873-3476
This study reports an experimental approach to determine the contribution from two different components of surface energy on cohesion. A method to tailor the surface chemistry of mefenamic acid via silanization is established and the role of surface energy on cohesion is investigated. Silanization was used as a method to functionalize mefenamic acid surfaces with four different functional end groups resulting in an ascending order of the dispersive component of surface energy. Furthermore, four haloalkane functional end groups were grafted on to the surface of mefenamic acid, resulting in varying levels of acid-base component of surface energy, while maintaining constant dispersive component of surface energy. A proportional increase in cohesion was observed with increases in both dispersive as well as acid-base components of surface energy. Contributions from dispersive and acid-base surface energy on cohesion were determined using an iterative approach. Due to the contribution from acid-base surface energy, cohesion was found to increase ∼11.7× compared to the contribution from dispersive surface energy. Here, we provide an approach to deconvolute the contribution from two different components of surface energy on cohesion, which has the potential of predicting powder flow behavior and ultimately controlling powder cohesion.
Johari K, Saman N, Song ST, et al., 2014, Study of Hg( II) Removal From Aqueous Solution Using Lignocellulosic Coconut Fiber Biosorbents: Equilibrium and Kinetic Evaluation, CHEMICAL ENGINEERING COMMUNICATIONS, Vol: 201, Pages: 1198-1220, ISSN: 0098-6445
Cole K, Buffler A, Cilliers JJ, et al., 2014, A surface coating method to modify tracers for positron emission particle tracking (PEPT) measurements of froth flotation, POWDER TECHNOLOGY, Vol: 263, Pages: 26-30, ISSN: 0032-5910
Puncochova K, Heng JYY, Beranek J, et al., 2014, Investigation of drug-polymer interaction in solid dispersions by vapour sorption methods, INTERNATIONAL JOURNAL OF PHARMACEUTICS, Vol: 469, Pages: 159-167, ISSN: 0378-5173
Smith RR, Williams DR, Burnett DJ, et al., 2014, A New Method To Determine Dispersive Surface Energy Site Distributions by Inverse Gas Chromatography, Langmuir, Vol: 30, Pages: 8029-8035, ISSN: 1520-5827
A computational model to predict the relative energy site contributions of a heterogeneous material from data collected by finite dilution–inverse gas chromatography (FD-IGC) is presented in this work. The methodology employed a multisolvent system site filling model utilizing Boltzmann statistics, expanding on previous efforts to calculate “experienced energies” at varying coverage, yielding a retention volume distribution allowing calculation of a surface free energy distribution. Surface free energy distributions were experimentally measured for racemic ibuprofen and β-mannitol powders, the energies of each were found in the ranges 43–52 and 40–55 mJ/m2, respectively, over a surface coverage range of 0–8%. The computed contributions to surface energy values were found to match closely with data collected on macroscopic crystals by alternative techniques (±<1.5 mJ/m2).
Shah UV, Olusanmi D, Narang AS, et al., 2014, Effect of crystal habits on the surface energy and cohesion of crystalline powders, International Journal of Pharmaceutics, Vol: 472, Pages: 140-147, ISSN: 1873-3476
The role of surface properties, influenced by particle processing, in particle–particle interactions (powder cohesion) is investigated in this study. Wetting behaviour of mefenamic acid was found to be anisotropic by sessile drop contact angle measurements on macroscopic (>1 cm) single crystals, with variations in contact angle of water from 56.3° to 92.0°. This is attributed to variations in surface chemical functionality at specific facets, and confirmed using X-ray photoelectron spectroscopy (XPS). Using a finite dilution inverse gas chromatography (FD-IGC) approach, the surface energy heterogeneity of powders was determined. The surface energy profile of different mefenamic acid crystal habits was directly related to the relative exposure of different crystal facets. Cohesion, determined by a uniaxial compression test, was also found to relate to surface energy of the powders. By employing a surface modification (silanisation) approach, the contribution from crystal shape from surface area and surface energy was decoupled. By “normalising” contribution from surface energy and surface area, needle shaped crystals were found to be ∼2.5× more cohesive compared to elongated plates or hexagonal cuboid shapes crystals.
Cai X, Heng J, 2014, Particle Science and Engineering, Publisher: Royal Society of Chemistry, ISBN: 9781849739573
Discussing the state of the art research in particle science and technology and their roles in the environment, this book will contain a selection of high quality papers from the UK-China International Particle Technology Forum IV held in ...
Lee K-Y, Blaker JJ, Murakami R, et al., 2014, Phase Behavior of Medium and High Internal Phase Water-in-Oil Emulsions Stabilized Solely by Hydrophobized Bacterial Cellulose Nanofibrils, LANGMUIR, Vol: 30, Pages: 452-460, ISSN: 0743-7463
Parambil JV, Poornachary SK, Tan RBH, et al., 2014, Template-induced polymorphic selectivity: the effects of surface chemistry and solute concentration on carbamazepine crystallisation, Crystengcomm, Vol: 16, Pages: 4927-4930, ISSN: 1466-8033
Cooling crystallisation of carbamazepine solution in glass vials functionalised with different silane molecules resulted in preferential nucleation of metastable form II or stable form III polymorphs within a definite range of supersaturation. In contrast, the two crystal forms nucleated concomitantly on a control substrate under similar solution conditions.
Hedberg S, Quigley A, Heng JYY, et al., 2014, Self-interaction chromatography (SIC) of mabs: New methods for estimating the dead volume in SIC and using sic to predict mab stability, Pages: 897-907
Copyright © (2014) by AIChE All rights reserved. Protein-protein molecular interactions are known to be involved in protein solution aggregation behaviour; however the mechanisms leading to protein aggregation are still not fully understood. The osmotic second virial coefficient (B22) is a fundamental physiochemical property that describes proteinprotein interactions in solution, which can be a useful tool to predict aggregation propensity of proteins. This work includes two experimental SIC studies on both model proteins and therapeutic mAbs of different sizes. The first study is an evaluation of two different experimental techniques used to determine SIC dead volumes and the second study uses SIC results for mAb to predict stability. Accurate dead retention volumes are essential for the accurate determinations of B22. The traditional method of estimating dead volume for SIC includes the use of a dead column (without protein immobilised) where the retention volume for proteins can be established. For this technique the dead volume was established for the proteins over a wide range of solution conditions (pH and salt concentrations), and then compared with a new method, where a number of non-interacting dextrans of different molecular weights (MW) (including the MW's of the protein) were employed to find the dead retention volume. The results for the traditional technique with a dead column changed depending on the protein used; only certain model proteins kept a constant dead retention volume when the pH was changing under a constant high salt concentration to minimise protein-surface interactions. Several proteins, including the mAb, exhibited an increased dead retention volume especially when exposed to lower pH. From this it can be concluded that there is no absolute dead volume that can be determined by this technique which are independent of solution conditions. The new technique involving dextrans gives a better overall result for the dead volume for pro
Ali SSM, Heng JYY, Nikolaev AA, et al., 2013, Introducing inverse gas chromatography as a method of determining the surface heterogeneity of minerals for flotation, POWDER TECHNOLOGY, Vol: 249, Pages: 373-377, ISSN: 0032-5910
Kwek JW, Heng D, Lee SH, et al., 2013, High speed imaging with electrostatic charge monitoring to track powder deagglomeration upon impact, JOURNAL OF AEROSOL SCIENCE, Vol: 65, Pages: 77-87, ISSN: 0021-8502
Quigley A, Heng JYY, Liddell JM, et al., 2013, The accurate measurement of second virial coefficients using self-interaction chromatography: Experimental considerations, EUROPEAN JOURNAL OF PHARMACEUTICS AND BIOPHARMACEUTICS, Vol: 85, Pages: 1103-1111, ISSN: 0939-6411
Al-Hashmi AR, Luckham PF, Heng JYY, et al., 2013, Adsorption of High-Molecular-Weight EOR Polymers on Glass Surfaces Using AFM and QCM-D, ENERGY & FUELS, Vol: 27, Pages: 2437-2444, ISSN: 0887-0624
Poornachary SK, Parambil JV, Chow PS, et al., 2013, Nucleation of Elusive Crystal Polymorphs at the Solution-Substrate Contact Line, CRYSTAL GROWTH & DESIGN, Vol: 13, Pages: 1180-1186, ISSN: 1528-7483
Delmas T, Shah UV, Roberts MM, et al., 2013, Crystallisation of the orthorhombic form of acetaminophen: Combined effect of surface topography and chemistry, POWDER TECHNOLOGY, Vol: 236, Pages: 24-29, ISSN: 0032-5910
Khoo JY, Shah UV, Schaepertoens M, et al., 2013, Process-induced phase transformation of carbamazepine dihydrate to its polymorphic anhydrates, POWDER TECHNOLOGY, Vol: 236, Pages: 114-121, ISSN: 0032-5910
Wang GD, Heng JYY, Williams DR, 2013, Dilatometry of powder compacts - Characterizing amorphous-crystalline transformations, POWDER TECHNOLOGY, Vol: 236, Pages: 12-16, ISSN: 0032-5910
Kwek JW, Heng D, Lee SH, et al., 2013, Visualizing Powder De-agglomeration upon Impact with Simultaneous Flowing Charge Behaviour, POWDERS AND GRAINS 2013, Vol: 1542, Pages: 1003-1006, ISSN: 0094-243X
Ho R, Heng JYY, 2013, A Review of Inverse Gas Chromatography and its Development as a Tool to Characterize Anisotropic Surface Properties of Pharmaceutical Solids, KONA POWDER AND PARTICLE JOURNAL, Pages: 164-180, ISSN: 0288-4534
Kwek JW, Jeyabalasingam M, Ng WK, et al., 2012, Comparative Study of the Triboelectric Charging Behavior of Powders Using a Nonintrusive Approach, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 51, Pages: 16488-16494, ISSN: 0888-5885
Burnett DJ, Khoo J, Naderi M, et al., 2012, Effect of Processing Route on the Surface Properties of Amorphous Indomethacin Measured by Inverse Gas Chromatography, AAPS PHARMSCITECH, Vol: 13, Pages: 1511-1517, ISSN: 1530-9932
Ho R, Naderi M, Heng JYY, et al., 2012, Effect of Milling on Particle Shape and Surface Energy Heterogeneity of Needle-Shaped Crystals, PHARMACEUTICAL RESEARCH, Vol: 29, Pages: 2806-2816, ISSN: 0724-8741
Tsekova DS, Williams DR, Heng JYY, 2012, Effect of surface chemistry of novel templates on crystallization of proteins, CHEMICAL ENGINEERING SCIENCE, Vol: 77, Pages: 201-206, ISSN: 0009-2509
Shah UV, Allenby MC, Williams DR, et al., 2012, Crystallization of Proteins at Ultralow Supersaturations Using Novel Three-Dimensional Nanotemplates, CRYSTAL GROWTH & DESIGN, Vol: 12, Pages: 1772-1777, ISSN: 1528-7483
Shah UV, Williams DR, Heng JYY, 2012, Selective Crystallization of Proteins Using Engineered Nanonucleants, CRYSTAL GROWTH & DESIGN, Vol: 12, Pages: 1362-1369, ISSN: 1528-7483
Wang GD, Mallet FP, Ricard F, et al., 2012, Pharmaceutical nanocrystals, Current Opinion in Chemical Engineering, Vol: 1, Pages: 102-107
Parambil JV, Schaepertoens M, Williams DR, et al., 2011, Effects of Oscillatory Flow on the Nucleation and Crystallization of Insulin, CRYSTAL GROWTH & DESIGN, Vol: 11, Pages: 4353-4359, ISSN: 1528-7483
Ho R, Dilworth SE, Williams DR, et al., 2011, Role of Surface Chemistry and Energetics in High Shear Wet Granulation, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 50, Pages: 9642-9649, ISSN: 0888-5885
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