Publications by authors named "Gavin Walker"

Here, we report an improved synthesis of the bulky phosphanide anion [P(SiPr)] in synthetically useful yields and its complexation to group 12 metals. The ligand is obtained as the sodium salt NaP(SiPr) in a 42% isolated yield and a single step from red phosphorus and sodium. This is a significantly higher-yielding and safer preparation compared to the previously reported synthesis of this ligand, and we have thus applied to the synthesis of the two-coordinate complexes M[P(SiPr)] (M = Zn, Cd, Hg).

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The identification of spray-drying processing parameters capable of producing particles suitable for pulmonary inhalation with retained bioactivity underpins the development of inhalable biotherapeutics. Effective delivery of biopharmaceuticals via pulmonary delivery routes such as dry powder inhalation (DPI) requires developing techniques that engineer particles to well-defined target profiles while simultaneously minimising protein denaturation. This study examines the simultaneous effects of atomisation gas flow rate on particle properties and retained bioactivity for the model biopharmaceutical lysozyme.

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This work evaluated the impact of incorporating 1% of commercial protein hydrolysates [rice protein hydrolysate (RPH), pea protein hydrolysate (PPH), and casein hydrolysate (CH)] on the functional, microstructure, and texture properties of set yogurt. Yogurt prepared with RPH exhibited the highest viability number of Streptococcus thermophilus. The addition of three hydrolysate types to yogurt revealed significant increases in the antioxidant and ACE-inhibitory activities, where the highest values were noted for the yogurt prepared with RPH.

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A sustainable low-carbon transition via electric vehicles will require a comprehensive understanding of lithium-ion batteries' global supply chain environmental impacts. Here, we analyze the cradle-to-gate energy use and greenhouse gas emissions of current and future nickel-manganese-cobalt and lithium-iron-phosphate battery technologies. We consider existing battery supply chains and future electricity grid decarbonization prospects for countries involved in material mining and battery production.

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Human milk (HM) fortification has been recommended for the nutritional optimization of very low-birthweight infants. This study analyzed the bioactive components of HM and evaluated fortification choices that could accentuate or attenuate the concentration of such components, with special reference to human milk-derived fortifier (HMDF) offered to extremely premature infants as an exclusive human milk diet. An observational feasibility study analyzed the biochemical and immunochemical characteristics of mothers' own milk (MOM), both fresh and frozen, and pasteurized banked donor human milk (DHM), each supplemented with either HMDF or cow's milk-derived fortifier (CMDF).

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In 2005, an applied theatre community outreach programme was launched to address low levels of HIV/AIDS awareness among farm workers in the Cape Winelands of South Africa. In cooperation with HIV testing organizations, the Lucky, the Hero mini-musical promoted regular HIV testing, condom use and acceptance of people living with HIV until being retired in 2017. Applying principles of the health belief model to interview data collected in 2015 from former Lucky, the Hero participants, this paper examines the effectiveness of the theatre production to achieve the behavioural outcomes of (i) encouraging regular HIV testing and ongoing awareness of HIV serostatus, and (ii) reducing AIDS-related social stigma.

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In this paper, we focus on providing a discrete formulation for a reduced aggregation population balance equation. The new formulation is simpler, easier to code, and adaptable to any type of grid. The presented method is extended to address a mixed-suspension mixed-product removal (MSMPR) system where aggregation and nucleation are the primary mechanisms that affect particle characteristics (or distributions).

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The family of van der Waals (vdW) materials is large and diverse with applications ranging from electronics and optoelectronics to catalysis and chemical storage. However, despite intensive research, there remains significant knowledge-gaps pertaining to their properties and interactions. One such gap is the interaction between these materials and hydrogen, a potentially vital future energy vector and ubiquitous processing gas in the semiconductor industry.

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Drug-mediated correction of abnormal biological zinc homeostasis could provide new routes to treating neurodegeneration, cancer, and viral infections. Designing therapeutics to facilitate zinc transport intracellularly is hampered by inadequate concentrations of endogenous zinc, which is often protein-bound in vivo. We found strong evidence that hydroxychloroquine, a drug used to treat malaria and employed as a potential treatment for COVID-19, does not bind and transport zinc across biological membranes through ionophoric mechanisms, contrary to recent claims.

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Pandemics and epidemics are continually challenging human beings' health and imposing major stresses on the societies particularly over the last few decades, when their frequency has increased significantly. Protecting humans from multiple diseases is best achieved through vaccination. However, vaccines thermal instability has always been a hurdle in their widespread application, especially in less developed countries.

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It is impossible to optimize a process for a target drug product with the desired profile without a proper understanding of the interplay among the material attributes, the process parameters, and the attributes of the drug product. There is a particular need to bridge the micro- and mesoscale events that occur during this process. Here, we propose а molecular engineering methodology for the continuous cocrystallization process, based on Raman spectra measured experimentally with a probe and from quantum mechanical calculations.

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The mechanochemical synthesis of cocrystals has been introduced as a promising approach of formulating poorly water-soluble active pharmaceutical ingredients (APIs). In this study, hot-melt extrusion (HME) as a continuous process and grinding and ball milling as batch processes were employed to explore the feasibility of cocrystallization. Ciprofloxacin (CIP) and isonicotinic acid (INCA) were selected as the model API and coformer.

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South Africa recorded and estimated 230,000 new infections in 2020, and low levels of AIDS risk awareness remain prevalent among the nation's youth. While public health awareness initiatives continue to be necessary, the large quantity of AIDS-related content that has permeated the media landscape since the start of the epidemic has resulted in increasing indifference to health messaging. Drawing from the concept of referent emotional responses, this article analyzes the reception of "Sing," an HIV/AIDS awareness music video characterized by emotive visual representations of AIDS.

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The importance of zinc in biology has gained greater recognition in recent years due to its essential contributions to the function of many endogenous enzymes. Disruption of zinc homeostasis may be useful in treating pathological conditions, such as Alzheimer's, and for antiviral purposes. Despite the growth of knowledge and increased interest in zinc, little is known about the structure and function of zinc ionophores.

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Wood (cellulose and lignin)-based hydrogels were successfully produced as platforms for drug-release systems. Viscoelastic and cross-linking behaviors of precursor solutions were tuned to produce highly porous hydrogel architectures via freeze-drying. Pore sizes in the range of 100-160 μm were obtained.

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Nowadays, sustainable materials are receiving significant attention due to the fact that they will be crucial for the development of the next generation of products and devices. In the present work, hydrogels have been successfully synthesized using lignin which is non-valorized biopolymer from the paper industry. Hydrogels were prepared via crosslinking with Poly(ethylene) glycol diglycidyl ether (PEGDGE).

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The application of in-line Raman spectroscopy to monitor the formation of a 1:1 cocrystal of ibuprofen (IBU) as a BCS class II drug and nicotinamide as coformer using hot-melt extrusion (HME) was investigated. The process was monitored over different experimental conditions inserting the Raman probe before the extruder die. Partial least square (PLS) was applied as a robust chemometric technique to build predictive models at different levels of chemometric by dividing the experimental data set into calibration and validation subsets.

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Continuous co-crystallization in a twin-screw granulator is a promising technology. In order to fundamentally optimize the process flow, it is necessary to investigate the kinetics of molecular interactions within the mixture and the effect of these interactions on co-crystal formation. In this study, the processes governing the co-crystallization of ibuprofen and nicotinamide were considered.

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Discovery of novel cocrystal systems and improvement of their physicochemical properties dominates the current literature on cocrystals yet the required end-product formulation is rarely addressed. Drug product manufacturing includes complex API solid state processing steps such as milling, granulation, and tableting. These all require high mechanical stress which can lead to solid-state phase transformations into polymorphs and solvates, or lead to dissociation of cocrystals into their individual components.

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In this study, an image processing technique is implemented to measure complete two-dimensional particle size and liquid content distribution (2D-distribution) of the granules produced in twin screw granulation (TSG). The effects of liquid binder viscosity and liquid to solid ratio (L/S) on the 2D-distribution, and the residence time distribution were studied. The effect of screw configuration on granule formation at different conditions was also investigated, were the mean residence time distribution (MRTD) in conveying elements decreases with the increase of L/S ratio and viscosity.

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Gender-based violence continues to be a leading determinant of South Africa's HIV/AIDS epidemic. As such, gender socialisation and de-normalisation of gender inequality and violence remain principal objectives for public health organisations. This article discusses youth reception of a mass media HIV/AIDS prevention campaign targeting gender inequality.

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The mechanical properties of powders determine the ease of manufacture and ultimately the quality of the oral solid dosage forms. Although poor mechanical properties of an active pharmaceutical ingredient (API) can be mitigated by using suitable excipients in a formulation, the effectiveness of that approach is limited for high dose drugs or multidrug tablets. In this context, improving the mechanical properties of the APIs through solid form optimisation is a good strategy to address such a challenge.

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In the pharmaceutical manufacturing, drug release behavior development is remained as one of the main challenges to improve the drug effectiveness. Recently, more focus has been done on using mesoporous silica materials as drug carriers for prolonged and superior control of drug release in human body. In this study, release behavior of paracetamol is developed using drug-loaded KCC-1-NH mesoporous silica, based on direct compaction method for preparation of tablets.

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The application of multi-dimensional population balance equations (PBEs) for the simulation of granulation processes is recommended due to the multi-component system. Irrespective of the application area, numerical scheme selection for solving multi-dimensional PBEs is driven by the accuracy in (size) number density prediction alone. However, mixing the components, i.

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In this study, a complete two dimensional (internal coordinates) population balance model (2D-PBM) is developed, calibrated and validated as a predictive tool for predicting the particle size and the liquid content distribution of the granules produced from twin screw granulation (TSG). The model is calibrated and validated using experimental distributions for the two internal coordinates that are captured using image processing. Granulation runs are conducted at multiple liquid to solid (L/S) ratios and liquid binder viscosities, and then used to calibrate and validate the 2D-PBM.

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