Particle stabilised thin films

Froth flotation is widely used by the mining industry to concentrate low grade metal ores. It uses the differences in surface properties between particles of the desired mineral and waste material to separate them using a mineralised froth. The properties of this particle stabilised mineralised froth impact on the efficiency of the separation process. Due to its dynamic and unstable nature it is difficult to study and remains relatively poorly understood. A deeper insight into the fundamental froth properties can be gained by using computer modelling techniques. Here a series of models are developed using the Surface Evolver (Brakke 1992). They are used to investigate the effects of particle shape, hydrophobicity and packing arrangement on the critical capillary pressure of thin films. Three dimensional simulations of uniformly spaced spherical particles in the film are compared to existing two dimensional (2D) analytical models. It is shown that 2D models over predict the capillary pressure required to rupture the film. The models are developed further to simulate randomly distributed particles in a periodic film. The results are then used to derive an expression for film stability based on particle packing density and contact angle. The different possible failure modes of double layers of particles are also investigated and the conditions under which they occur identified. A versatile model for simulating non-spherical particles in an interface or film is also derived and used to find the energetically stable orientations of orthorhombic particles at an interface. This information is then used to investigate the effect of particle orientation on the capillary pressure required to rupture the film. It is shown that the combination of contact angle and shape affect the particle orientation. Certain orientations are then shown to reduce the critical capillary pressure of the film by up to 70 %

MicroRNAs - small RNAs with a big influence on brain excitability

MicroRNAs are non-coding RNAs, approximately 22 nt in length, which serve to negatively regulate gene expression through binding to complementary sequences in the 3' untranslated region (3'UTR) of target mRNA. The microRNA-target interaction does not require perfect complementarity, meaning that an individual microRNA often has a pool of hundreds of gene targets. Equally, one 3'UTR can contain target sites for many different microRNAs. This gives rise to a complex web of molecular interactions. An emerging concept is that microRNAs have a role as 'master' regulators of certain cellular properties, simultaneously mediating the subtle repression of multiple related genes within a pathway or system, thereby achieving a common phenotypic output. One such example is regulation of brain excitability. There are numerous examples of microRNAs which can target ion channels, ion transporters and genes associated with synaptic transmission. Often, the expression of the microRNA itself is regulated in an activity-dependent manner, thereby forming homeostatic loops. Limitations in our understanding arise from the sheer complexity of microRNA-target interactions, which are difficult to capture experimentally and computationally. Further, many microRNA studies rely on animal model systems, but many microRNAs (and mRNA targets) have sequences which are either not conserved or are entirely unique in the human brain. This leaves many exciting and challenging opportunities to further progress the field in an attempt to fully understand the roles of microRNAs in brain function

Electromagnetic transitions as a probe for Superdeformation in 28Si

There is great interest in superdeformation in light nuclei, A < 40 region, in particular alpha-conjugate nuclei in the sd-shell. Enhanced collectivity for such light systems opens new opportunities to test nuclear-structure theories. Antisymmetrized molecular dynamics, large-scale shell model and beyond mean-field calculations which predict superdeformed structures in these regions can be validated and tuned with the aid of experimental evidence of superdeformed bands in light nuclei. A J(pi) = 6+ state at 12.865 MeV in 28Si with a measured B(E2) value of more than 25 W.u for the transition to the 10.946-MeV J(pi) = 4+ state is indicative of a highly collective transition and has been thought to form part of a candidate SD band. Measurements of in-band electromagnetic transitions are required to fully describe this proposed SD band. The CAGRA campaign is a combination of small-angle inelastic scattering with high resolution gamma-ray spectroscopy. This method preferentially populates low-spin and isoscalar natural parity states. A 12 Clover + 4 LaBr3 array was used in coincidence with the high resolution Grand Raiden spectrometer to momentum analyse inelastically scattered alpha-particles. The experiment was performed at the Research Center for Nuclear Physics (RNCP) of Osaka University, Japan. This thesis will focus on the experimental challenges, analysis and results of the 28Si(alpha,alpha') reaction at 9.1 degrees with E_beam = 130 MeV impinged on a natural Si target. The first upper limits of the in-band gamma-ray transition strength of 6.08 W.u from the J(pi) = 4+ to J(pi) = 2+ of the proposed superdeformed band in 28Si has been measured. This has the potential to constrain future theoretical predictions of superdeformation in 28Si

Gene Therapy for Neurological Disease: State of the Art and Opportunities for Next-generation Approaches

Gene therapy for rare monogenetic neurological disorders is reaching clinics and offering hope to families affected by these diseases. There is also potential for gene therapy to offer new and effective treatments for common, non-genetic disorders. Treatments for Parkinson's Disease are in clinical trials, and treatments for refractory epilepsies are due to enter first-in-human clinical trials in 2022. Gene therapies for these disorders are based on delivering genes that address the mechanism of the disease, not repairing a mutated gene. Similar 'mechanistic' gene therapies could offer treatments to a wide range of neurological and neuropsychiatric diseases where there is a known mechanism that could be restored using gene therapy. However, the permanent nature of most gene therapies is a serious drawback for translation of gene therapies to a wide-range of diseases because it could present risk of irreversible adverse effects. Several lines of research are aimed at developing gene therapy approaches that allow for the treatment to be turned on and off, including: using proteins activated by exogenous ligands, and promoters turned on by activators. We review these approaches and propose an overall de-risking strategy for gene therapy for common neurological and psychiatric diseases. This approach is based on using a temporary mRNA-based treatment to initially assess efficacy and safety of the planned manipulation, and only following with permanent, virally-delivered treatment if the approach appears safe and effective

The removal of anionic surfactant from commercial laundry wastewater with reverse osmosis membrane

Thesis (MEng (Chemical Engineering))--Cape Peninsula University of Technology, 2020Fresh, clean water has always been critical for the world's social development. The current water scarcity will only worsen unless measures are put in place to either reduce water usage or clean and reuse greywater. In areas with limited water resources, affordable technologies can be used to treat greywater and increase the water supply. Greywater sources that can be reused include domestic, hospital and industrial laundry wastewater. These wastewaters contain different chemicals such as organic and inorganic constituents, which make it difficult to treat. Microfiltration and ultrafiltration are examples of physical filtration processes that can reduce turbidity and pathogens sufficiently, but struggle to remove organics. Therefore, implementing an additional step such as reverse osmosis (RO) could be the solution in the removal of harmful chemicals in greywater. Unfortunately, the salts that are removed from the water, precipitate on the membrane surface, thus, decreasing the overall process efficiency, due to fouling and scaling. Scaling causes decline in permeation flux, degeneration of membranes, production loss and higher operating costs. This occurrence of fouling cannot be completely isolated; however, it can be minimised. There are two approaches for dealing with the fouling effect, namely, minimization and remediation. Remediation focuses more on frequent chemical cleaning. By using suitable pre-treatment measurements upstream of RO, scale formation can be minimised. In this study, the use of a commercial antiscalant was examined in the treatment of laundry wastewater influent. The removal of anionic surfactants and COD’s from this effluent with a low-pressure, extra low energy, reverse osmosis membrane for reuse application was investigated. The effect of different laundry detergent feed concentrations on operational parameters such as the membrane salt rejection and permeate flow rate (flux) was also analysed. The effect of different antiscalant concentrations to minimise scaling was also evaluated. Membrane fouling and remediation was evaluated by selected membrane surface characteristics. Model laundry wastewater was treated using a bench-scale reverse osmosis unit. The effects of laundry detergent concentration and antiscalant dosage on the permeate flow rate (flux) and rejection characteristics of the membrane were examined. Removal efficiencies for surfactant and COD concentration were analysed as an indication of membrane performance. A detailed examination of membrane fouling was done by investigating membrane surface characteristics using Scanning Electron Microscopy (SEM); Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Energy Dispersive X-Ray Spectroscopy (EDX), before and after antiscalant addition. Design Expert 11 was used to generate a predictive model to describe the behaviour of permeate flux decline over time. ATR-FTIR revealed all the characteristic peaks on a virgin extra low energy (XLE) polyamide thin film composite membrane, in its clean state. It was observed that more foulant is deposited onto the surface of membranes with lower or no antiscalant dosage compared to the higher antiscalant dosed membranes. A morphological change of the membranes was observed using SEM analysis. The hindered attachment of scalant on the surface of the membranes resulted in a much lower rate of flux decline when compared to membranes with no antiscalant addition. EDX revealed that the amount of carbon decreased with an increase in laundry detergent amount (concentration). This could be due to the carbonyl group present in the PA layer being masked by the foulant layer. The flux decline could be associated with the fouling phenomenon caused by the accumulation of anionic surfactant molecules on the membrane surface, where the build-up of a concentration polarisation layer and/ the or the entrapment in the polyamide layer. Surfactant rejection exceeded 99.8% in almost all the experimental runs over a range of varied feed concentrations. An average COD removal throughout was 91-96%. It must be noted that the COD removal during the Percentage removal (COD and average EC) of the membranes are all significantly high, between 96-98% removal for average EC and between 91-96% removal for COD, however it was observed that membranes with membranes with no anti-scalant addition performed slightly better than membranes with anti-scalant dosing. It was observed that the predictive model successfully described the permeate flux decline of laundry wastewater using an RO membrane within the design space of the model. It can be confirmed that the membrane performance investigated using model laundry wastewater could be improved when using commercial antiscalant

Strengthening charity regulation in England and Wales? The Charities (Protection and Social Investment) Act 2016 and the impact of academic witnesses

Research on charity regulation is frequently triggered by charity law developments. However, it is often unclear what impact such research has on policy makers and parliamentarians shaping charity regulation. Both authors of this paper were called to give evidence to the Parliamentary Joint Committee examining the draft Bill that led to the Charities (Protection and Social Investment) Act 2016. We review the possible impact of our evidence on the ultimate Act and on charity regulation more broadly