The manufacture and evaluation of ceramic membranes

Thesis (MScEng)--University of Stellenbosch, 2001.ENGLISH ABSTRACT: Inorganic membranes offer numerous advantages, such as stability at high temperatures and a long lifetime. Two Russian professors invented and patented a method for manufacturing a tubular ceramic membrane [Linkov & Belyakov, 1996]. Their membranes were used in the water purification industry and in gas separation research at the University of Stellenbosch [Keuier, 2000], but the performance of the membranes have been reported to be inconsistent. This project investigates the manufacturing process for these membranes in an attempt to improve their inconsistent performance. It also provides useful insight into relevant methods of evaluation. Thirty-two cerarruc membranes were successfully manufactured according to the patent by Linkov and Belyakov [1996], with slight modifications to the original manufacturing process. It was found for example that, to obtain membranes with a thickness of 1 mm, the casting suspension should contain 1.85 grams of water per gram of oxides, instead of the 1.15 grams of water per gram of oxides according to Linkov and Belyakov [1996]. The quality of the gypsum mould and the drying of the green body were found to be the most difficult steps in the manufacturing process. Gas permeabilities for the manufactured membranes were typically lxIO-5 mol/misl'a for argon and nitrogen and 4.SxIO-5 mol/rrr'sl'a for hydrogen. Water permeabilities for the manufactured membranes were typically 600 Vm2hbar. Gas permeability coefficients for the manufactured membranes were typically SxIO-15 m2 for nitrogen and argon and 8xIO-15 m2 for hydrogen. The water permeability coefficients were typically 1.7xl 0-15 m2 . The gas and water permeabilities for the manufactured membranes were typically 5 and 10 times higher than the permeability values for membranes manufactured by Linkov. Gas and liquid permeability coefficients for the manufactured membranes, taking into account the thickness of the membranes, were 7 and 14 times higher than those achieved with Linkov's membranes. Linkov's membranes were on average thinner than the manufactured membranes, while the permeability of the manufactured membranes was higher, explaining the high permeability coefficients. The nitrogen and argon permeabilities, as well as their permeability coefficients were found to increase linearly with increasing pressure difference. However, the hydrogen permeability and permeability coefficients as well as the water permeability coefficients, were pressure independent. The gas permeability results also indicated that the permeability of the manufactured membranes increased with increasing sintering time and temperature. Combining the gas permeability results with the selectivity results, manufactured membranes with higher gas permeability had the same selectivity as Linkov's membrane. Therefore the manufactured membranes had a higher capacity than Linkov's membranes, with the same selectivity. For the manufactured membranes, however, a lower mechanical strength was reported, typically 9 N/mm2 , compared to the mechanical strength of Linkov's membrane which was roughly 10 times higher. To further improve the membranes, a number of options can be investigated: • The influence of a higher zirconia content on the ceramic membranes (between 29W'1o and 36.6W'1o for best mechanical strength). • Increasing of the sintering time and temperature for a more sintered and mechanically stronger membrane. • Examining the relationship between the permeability and mechanical strength of the membranes.AFRIKAANSE OPSOMMING: Anorganiese membrane besit 'n aantal voordele, soos stabiliteit by hoë temperatuur toepassings en 'n langer leeftyd. Twee Russiese professore het 'n vervaardigingsmethode vir buisvormige keramiekmembrane uitgevind en gepatenteer [Linkovand Belyakov, 1996]. Hulle membrane was gebruik in die watersuiwerings industrie sowel as in 'n gasskeidings ondersoek by die Universiteit van Stellenbosch [Keuier, 2000], maar die prestasie van die membrane was wisselvallig. Hierdie projek ondersoek die vervaardigings metode vir hierdie kerarniekmembrane in 'n poging die wisselvallige prestasie van die membrane te verbeter. Die projek gee ook bruikbare insig in relevante toetsmetodes vir die vervaardigde membrane. Twee en dertig keramiekmembrane was suksesvol vervaardig volgens die patent van Linkoven Belyakov [1996], met klein veranderings. Dit was byvoorbeeld gevind dat, om membrane te vervaardig met 'n dikte van 1 mm, die gietsuspensie 1.85 gram water per gram oxide moet bevat in plaas van een gram water per een gram oxides soos volgens Linkoven Belyakov [1996]. Die kwaliteit van die gips vorm en die droog van die groen liggaam was die moeilikste beheerbare stappe in die vervaardigingsproses. Die gasdeurlaatbaarheid van die vervaardigde membrane was tipies Ix 10-5 mollm2sPa vir argon en stikstof en 4.5xl0-s mol/m'sl'a vir waterstof Waterdeurlaatbaarheid van die vervaardigde membrane was 600 l/rrr'hbar. Gasdeurlaatbaarheidskoeffisiente vir die vervaardigde membrane was tipies 5xl 0-15 m2 vir argon en stikstof en 8xl 0-15 m2 vir waterstof Die waterdeurdringbaarheidskoeffisiente was tipies 1.7xl 0-15 m2 . Die gas- en waterdeurlaatbaarheid vir die vervaardigde membrane was tipies 5 en 10 maal hoër as die deurlaatbaarheid waardes vir membrane wat deur Linkov vervaardig is. Gas- en waterdeurlaatbaarheidskoeffisiente vir die vervaardigde membrane, wat deur die dikte van die membrane beinvloed word, was 7 en 14 maal hoër as die bereik met Linkov se membrane. Linkov se membrane was gemiddeld dunner as die vervaardigde membrane, terwyl die deurlaatbaarheid van die vervaardigde membrane hoër was, wat die hoë deurlaatbaarheidskoeffisiente verklaar. Daar was gevind dat die argon- en stikstofdeurlaatbaarhede sowel as hulle deurlaatbaarheidskoeffisiente lineêr toeneem met toenemende drukverskil. Die waterstofdeurlaatbaarheid en -deurlaatbaarheidskoeffisiente sowel as die waterdeurlaatbaarheidskoeffisiente egter, was onafhanklik van die drukverskil. Die gasdeurlaatbaarheid resultate het ook aangedui dat die deurlaatbaarheid van die vervaardigde membrane toeneem met toenemende sintertyd en -ternperatuur. Wanneer die gasdeurlaatbaarheid resultate gekombineer word met die selektiwiteit resultate blyk dit dat, terwyl dat die vervaardigde membrane 'n hoër gasdeurlaatbaarheid het as Linkov se membrane, hulle nog steeds dieselfde selektiwiteit het. Dit beteken dat die kapasiteit van die vervaardigde membrane hoër is, terwyl die selektiwiteit van die skeidingsproses behou word. Vir die vervaardigde membrane was 'n laer meganiese sterkte gevind, tipies 9 N/mm2 , terwyl die meganiese sterkte van Linkov se membrane omtrend 10keer hoër was. Verskeie opsies kan ondersoek word om die membrane te verbeter: • Die invloed van 'n hoër zirkonia inhoud op die keramiekmembrane (tussen 29m% en 36.6m% vir beste meganiese sterkte). • Verlenging van die sintertyd en -temperatuur om 'n meer gesinterde en meganies sterker keramiekmembraan te verkry. • Ondersoek na die verhouding tussen deurlaatbaarheid en die sterkte van die membraan

MG rituximab vs eculizumab

MG rituximab vs eculizumab in a retrospective cohort studyTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Assessment of upper extremity movement performance of patients with obstetric brachial plexus palsy

Coping strategies of patients with obstetric brachial plexus palsy (OBPP) are highly individual. Up to now, individual movement performance is assessed by visual observations of physicians or therapists - a procedure, which is highly subjective and lacks objective data. However, objective data about the individual movement performance are the key to evidence-based and individualized treatment. In this paper, a new approach is presented, which provides objective information about the upper extremity movement performance of patients with OBPP. The approach is based on the use of accelerometers in combination with a classification procedure. The movement performance of 10 healthy volunteers and 41 patients with OBPP has been evaluated by experienced physiotherapists and has been assigned to one of 4 categories representing the Mallet Scale (MS) IV to I. Three triaxial-accelerometers were placed at chest, upper arm and wrist of the affected side of the patient. Acceleration signals have been recorded during repetitive movements with relevance regarding daily life. Here, especially the results from the “hand to mouth” task are presented. From the 9 recorded acceleration signals 13 relevant features were extracted. For each of the 13 features 4 thresholds have been determined distinguishing best between the 4 patient categories of the MS and the healthy subjects. With respect to the thresholds each feature value has been assigned to the discrete numbers 0, 1, 2, 3 or 4. Afterwards, each discrete number has been weighted by a factor regarding the correlation between the feature’s value and the MS score. The resulting weighted discrete numbers of all 13 features have been added resulting in a score, which quantifies the individual upper extremity movement performance. Based on this score the movement performance of each patient has been assigned to the classes “very good”, “good”, “regular” and “bad”. All movements of the 10 healthy volunteers were classified as “very good”. The movement performance of two patients MS IV were classified as “very good” as well and the movements of the other 16 patients as “good”. The movements of the entire group of MS III patients fell into the class “regular”. Just one MS II patient was assigned to the class “regular” while the others were classified as “bad”. It was not possible to classify the movements of MS I patients. This was mainly due to the fact that none of these patients MS I was able to complete the task successfully. The developed approach demonstrated its ability to quantify the movement performance of upper extremity movements based on accelerometers. This provides an easy to use tool to assess patient’s movement strategies during daily tasks for diagnosis and rehabilitation

Drug induced micellization into ultra-high capacity and stable curcumin nanoformulations: Comparing in vitro 2D and 3D-tumor model of triple-negative breast cancer

This manuscript describes a ultra-high loaded nanoformulation of curcumin. This compound is extremely water insoluble but could be dissolved using poly(2-oxazoline)/poly(2-oxazine) based polymer amphiphiles. The resulting formulations were thoroughly characterized in solution and solid form by NMR, dynamic light scattering, electron microscopy, HPLC zeta potential measurements, XRD, respectively. Biological activity was ensured and compared in 2D and 3D cell culture

Drug induced micellization into ultra-high capacity and stable curcumin nanoformulations: Comparing in vitro 2D and 3D-tumor model of triple-negative breast cancer

This manuscript describes a ultra-high loaded nanoformulation of curcumin. This compound is extremely water insoluble but could be dissolved using poly(2-oxazoline)/poly(2-oxazine) based polymer amphiphiles. The resulting formulations were thoroughly characterized in solution and solid form by NMR, dynamic light scattering, electron microscopy, HPLC zeta potential measurements, XRD, respectively. Biological activity was ensured and compared in 2D and 3D cell culture

An enigmatic case of cortical anopsia: Antemortem diagnosis of a 14-3-3 negative Heidenhain-variant MM1-sCJD

Sporadic Creutzfeldt-Jakob disease is the predominant type of human prion disease. While routine diagnostic in phenotypic cases has advanced considerably, the clinical heterogeneity and rarity of subtypes continue to constitute a major clinical and diagnostic challenge. Here, we report a peculiar case of the Heidenhain-variant of MM1 sporadic Creutzfeldt-Jakob disease presenting as a stroke mimic in an 81-year-old patient with a rapid and clinically distinct course of disease as compared to previously reported cases. While 14-3-3 protein was negative, clinical findings substantiated by 18F-FDG-PET imaging and RT-QuIC-Assay were able to establish the diagnosis. We conclude that in cases presenting with rapid progressive dementia secondary to sudden cortical anopsia the Heidenhain-variant of CJD should be considered

The Innate Immune Response Characterizes Posterior Reversible Encephalopathy Syndrome

While posterior reversible encephalopathy syndrome (PRES) is often characterized by an inflammatory cerebrospinal-fluid (CSF) profile, knowledge of immune cell patterns in PRES is lacking. Thus, we retrospectively characterized CSF and peripheral blood (PB) from 15 PRES patients, which we analyzed by multidimensional flow cytometry (FC). Results were compared to 72 controls, as well as to 9 patients with progressive multifocal leukoencephalopathy (PML, as a relevant differential diagnosis) and 15 multiple sclerosis patients (MS, as a classical neuroinflammatory disorder), respectively. Total protein level in CSF from PRES patients was elevated compared to that in controls, but not to MS and PML. In-depth FC analysis revealed no differences for adaptive immune cells (B cells, plasma cells, CD