•Evaluation of the modelling approaches of selected Rocky and STAR-CCM+DEM models.•Effect of different parameters for DEM based packing models investigated.•Discrepancies in the published results ...identified and addressed.•Correlations for the prediction of the axial variation in porosity.•Piece-wise constant distribution of the regional average porosity.
The paper deals with the evaluation of the distribution of the porosity of a model of the HTR-10 packed bed reactor which was generated using a Discrete Element Method (DEM) approach. The porosity of the packed bed was determined using semi-analytical methodologies. To evaluate the validity of the model, selected aspects of the DEM approach were first investigated. It was found that the appropriate packing method is to drop the spheres at a specified rate from the top of the packed bed domain. The preferable model for the contact force between the spheres was found to be the Hertz-Mindlin model. It was also established that the Young’s modulus of the spheres should be larger than 0.1 GPa. A value of less than 0.1 GPa has a marked negative effect on the porosity. The values for the porosity predicted by previously proposed correlations for the radial and axial variations in porosity were determined to be too small. From the analysis of the packed bed model, the overall porosity was found to be 0.382, whilst the average porosities of the pipe, conical and cylindrical sections were found to be 0.439, 0.378 and 0.381 respectively. Correlations are derived to describe the axial variation of the porosity in the pipe, conical and cylindrical regions. A piece-wise constant description of the distribution in the porosity is finally provided by dividing the packed bed into 34 regions and determining the average porosity of each region.
According to reports in South Africa, treatment failure rates for rifampicin-resistant TB (RR-TB) are significant and below the WHO target of ≥70%. HIV infection and the use of highly active ...antiretroviral therapy (HAART) influence how patients receiving anti-TB drugs respond to therapy. In the treatment of RR-TB, more recent medications, including bedaquiline, pretomanid and linezolid (BPaL), have shown promising results.
To assess treatment outcomes in RR-TB patients using BPaL and other second-line anti-TB drugs as recommended by the WHO in the South African population.
The databases Medline, PubMed, Google Scholar and Embase were searched for studies between 2015 and 2022, which investigated BPaL outcomes in South Africa.
Of the 27,259 participants, 21% were on bedaquiline, 1% were taking pretomanid and 9% were taking linezolid as part of their background regimen. About 68% of the patients were HIV-positive, with 59% of them taking HAART.
Overall, 66% of patients taking BPaL drugs as part of their background regimen had favourable treatment outcomes. Additionally, patients with RR-TB who were HIV-positive and taking HAART while receiving BPaL drugs as part of a background regimen had improved treatment outcomes.
The High Temperature Test Unit (HTTU) was an experimental set-up to conduct separate and integral effects tests of the Pebble Bed Modular Reactor (PBMR) core. The annular core consisted of a randomly ...packed bed of uniform spheres. Natural convection tests using both nitrogen and helium, and forced convection tests using nitrogen, were conducted. The maximum material temperature achieved during forced convection testing was 1200 °C. This paper presents the numerical analysis of the flow and temperature distribution for a forced convection test using 3D CFD as well as a 1D systems-CFD computer code. Several modelling approaches are possible, ranging from a fully explicit to a semi-implicit method that relies on correlations of their associated phenomena. For the comparison between codes, the analysis was performed using a porous media approach, where the conduction and radiative heat transfer were lumped together as an effective thermal conductivity and the convective heat transfer was correlated between the solid and gas phases. The results from both codes were validated against the experimental measurements. Favourable results were obtained, in particular by the systems-CFD code with minimal computational and time requirements.
This prospective study investigates whether measurement of plasma intestinal-fatty acid binding protein (I-FABP), a sensitive marker for small intestinal epithelial damage, improves non-invasive ...diagnosing of celiac disease (CD), and whether I-FABP levels are useful to evaluate mucosal healing in patients on a gluten-free diet (GFD). Ninety children with elevated tTG-IgA titres and HLA-DQ2/DQ8 positivity were included (study group). Duodenal biopsies were taken, except in those fulfilling the ESPGHAN criteria. Plasma I-FABP levels and tTG-IgA titres were assessed sequentially during six months of follow-up. Eighty children with normal tTG-IgA titres served as control group. In 61/90 (67.8%) of the children in the study group an increased I-FABP level was found; in all these children CD diagnosis was confirmed. Interestingly, in 14/30 (46.7%) children with slightly elevated tTG-IgA titres (<10x upper limit of normal), an increased I-FABP level was found. In all these children the diagnosis of CD was confirmed histologically. After gluten elimination for six weeks I-FABP levels had decreased towards levels in the control group. Measurement of plasma I-FABP, in addition to tTG-IgA, EMA-IgA and HLAtyping, enables non-invasive diagnosing of CD in a substantial number of children, and might therefore be of value in the diagnostic approach of CD.
•Evaluation of the porosity of the HTTU annular packed bed.•Angular and radial variation in porosity for bottom near-wall region characterized.•Standard deviation and skewness of angular at each ...radial position calculated.•Variation of tangentially averaged porosity in axi-symmetric r-z plane shown.•Average porosity and standard deviation for 20 selected regions presented.
In this paper a comprehensive analysis of the porosity of the annular packed bed of the High Temperature Test Unit (HTTU) is presented. The annular packed bed is generated using a Discrete Element Method (DEM) approach. Semi-analytical methods are then used to analyse the porosity. The quality and representativity of the packed bed are established by evaluating the overlaps between spheres and spheres and walls and comparing the axial and radial variations in porosity with available experimental and numerical data. The angular and radial variation of selected sphere layers in the bottom near-wall region was studied revealing how the spheres in the axial layers and radial rings are staggered with respect to each other. The analysis of the radial variation in porosity also included the standard deviation and the skewness of the angular porosity at each radial position. An analysis of the radial porosity of the layers revealed that only first layer next to the bottom is markedly affected by the bottom wall. The interference between the oscillatory porosity variations perpendicular to the inner, outer, and bottom walls of the annular packed bed is demonstrated by the plot of the variation in porosity on an axi-symmetric r-z plane. The annular packed bed is also divided into 20 regions and the average porosity and the standard deviation of the porosity for each region in provided.
Background. South Africa (SA) and other countries worldwide are experiencing extreme drought conditions. Since the start of the drought in SA, many ways of saving water have been proposed and ...innovative water-saving mechanisms have become part of the lives of communities. We investigated water use during surgical scrubbing procedures and possible interventions to reduce water consumption.Objectives. To compare water use during surgical hand preparation before and after the implementation of specific water-saving interventions.Methods. This was a non-randomised controlled study, following a before-and-after design, of orthopaedic theatre personnel scrubbing for surgical cases at Tygerberg Hospital, Cape Town. A control (CON) group (n=32) was established to observe standard practice for baseline measurements including total amount of water used, wash time and water flow rate during surgical hand preparation. After this, three interventions were randomly assigned to a single theatre each, where the same variables were measured. Intervention AS entailed using an alcohol scrub (n=18), intervention SN (n=12) had a dedicated assistant to open and close taps during scrubbing, and intervention SW (n=12) made use of adjusted tap levers to allow the surgeon to open and close taps more easily. Analysis of variance was used to detect global differences between groups, and Tukey’s post hoc test was performed to detect differences between groups.Results. Significant differences in water use (pConclusions. Water use during surgical hand preparation can easily be reduced by implementing easy and effective interventions. The practicality of interventions may differ between institutions, and their acceptance by surgical staff is important to ensure compliance. However, ensuring that alternative scrubbing options are available to surgical staff would equate to substantial savings over time.
Abstract
Background
there is a trend across Europe to enable more care at the community level. The Acute Geriatric Community Hospital (AGCH) in the Netherlands in an acute geriatric unit situated in ...a skilled nursing facility (SNF). It provides hospital-level care for older adults with acute medical conditions. The aim of this study is to identify barriers and facilitators associated with implementing the AGCH in a SNF.
Methods
semi-structured interviews (n = 42) were carried out with clinical and administrative personnel at the AGCH and university hospital and stakeholders from the partnering care organisations and health insurance company. Data were analysed using thematic analysis.
Results
facilitators to implementing the AGCH concept were enthusiasm for the AGCH concept, organising preparatory sessions, starting with low-complex patients, good team leadership and ongoing education of the AGCH team. Other facilitators included strong collaboration between stakeholders, commitment to shared investment costs and involvement of regulators.
Barriers to implementation were providing hospital care in an SNF, financing AGCH care, difficulties selecting patients at the emergency department, lack of protocols and guidelines, electronic health records unsuited for hospital care, department layout on two different floors and complex shared business operations. Furthermore, transfer of acute care to the community care meant that some care was not reimbursed.
Conclusions
the AGCH concept was valued by all stakeholders. The main facilitators included the perceived value of the AGCH concept and enthusiasm of stakeholders. Structural financing is an obstacle to the expansion and continuation of this care model.
•First detailed CFD model of a hybrid counter/parallel- solar air heater.•Inclusion of a solar load model in contrast to the commonly used constant heat flux boundary condition.•Validation of the CFD ...model.•Experimental and computational discussion of the efficiency of the hybrid solar air heater.
Solar air heaters may be used in a variety of applications such as space heating, pre-heating for industrial applications, drying of various materials and pre-heating for solar water desalinators. This research is aimed at evaluating a unique solar air heater design in terms of its thermal efficiency and temperature distributions within the solar air heater. The solar heater is unique as it combines parallel- and counter flows inside the heater in order to reduce mass and improve overall heat transfer. Current modelling techniques are not suitable to this type of SAH, as they apply to SAHs with simpler geometries, like counterflow heaters or parallel flow heaters. The solar air heater is evaluated using computational fluid dynamics and experiment. The computational models are validated experimentally. The computational models account for the solar load, surface to surface radiation, conduction, convection and turbulence. A screening of turbulence models is performed. The average conversion efficiency ranges between 23% and 83% and the average collector efficiency between 11% and 44%. The thermal efficiency values predicted by the computational models show good agreement with the experimentally derived values. The computational models over-predict the thermal efficiency by between 6.75% and 9.01% of the measured quantity, depending on the solar radiative power input used. The model predictions of temperatures show good qualitative agreement with the measured temperatures but do not compare well quantitatively for all points of comparison. The average error between predicted temperature and experimental results for the various points of comparison is 9.165 K.
Bronchiolitis is a common disorder in young children that often results in hospitalisation. Except for a possible effect of nebulised hypertonic saline (sodium chloride), no evidence-based therapy is ...available. This study investigated the efficacy of nebulised 3% and 6% hypertonic saline compared with 0.9% hypertonic saline in children hospitalised with viral bronchiolitis. In this multicentre, double-blind, randomised, controlled trial, children hospitalised with acute viral bronchiolitis were randomised to receive either nebulised 3%, 6% hypertonic saline or 0.9% normal saline during their entire hospital stay. Salbutamol was added to counteract possible bronchial constriction. The primary endpoint was the length of hospital stay. Secondary outcomes were need for supplemental oxygen and tube feeding. From the 292 children included in the study (median age 3.4 months), 247 completed the study. The median length of hospital stay did not differ between the groups: 69 h (interquartile range 57), 70 h (IQR 69) and 53 h (IQR 52), for 3% (n=84) and 6% (n=83) hypertonic saline and 0.9% (n=80) normal saline, respectively, (p=0.29). The need for supplemental oxygen or tube feeding did not differ significantly. Adverse effects were similar in the three groups. Nebulisation with hypertonic saline (3% or 6% sodium chloride) although safe, did not reduce the length of stay in hospital, duration of supplemental oxygen or tube feeding in children hospitalised with moderate-to-severe viral bronchiolitis.
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