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Bioflocculant producing bacillus megaterium from poultry slaughterhouse wastewater: elucidation of flocculation efficacy and mechanism
No full textThe study focused on isolating bioflocculant-producing microorganisms from poultry slaughterhouse wastewater (PSW). Microorganisms (n = 20) were isolated, and the D2 isolate, identified as Bacillus megaterium using 16S rDNA and RpoD (sigma 70), had maximum flocculation activity. Furthermore, characteristics of the bioflocculant produced by B. megaterium were determined, and the optimum storage conditions, including the flocculation mechanism, were identified. The bioflocculant was composed mainly of polysaccharides and proteins and was better stored frozen in a crude form. Furthermore, the flocculation efficacy was assessed using response surface methodology at pH 4 (min) and 9 (max), bioflocculant dosage of 1% (min) and 3% (max, v/v), indicating pH 6.5 and dosage of 2% (v/v) as optimum flocculation conditions for floc formation under ambient temperature. These results were further confirmed with microscopy assessments with zeta potential measurements confirming that the bioflocculant was ionic, albeit charge neutralization was not the primary mechanism for floc agglomeration. Hydrogen bonding was predominant, indicative of a neutralization-bridging mechanism, an assertion also based on the functional groups prevalent in the isolate-B. megaterium. The results obtained indicate that bioflocculants can be used to treat isolates that are sourced from wastewater
A qualitative study of the perceived benefits of participating in a spinal cord rehabilitation intervention in a low-middle income country
No full textPurpose:
Improving quality of life (QoL) is a major goal of rehabilitation following spinal cord injury (SCI). However, people with disabilities in resource constrained contexts have limited access to rehabilitation and poorer health outcomes, including QoL. There is a paucity of qualitative research on the experiences of persons with SCI involved in rehabilitation programmes in low-middle income countries. This study aimed to assess participants’ perceptions of the benefits of a 24-week SCI rehabilitation programme delivered as part of a pilot randomized controlled trial (RCT) in South Africa.
Materials and methods:
Sixteen participants, with chronic motor-incomplete tetraplegia, were enrolled in a two-arm pilot RCT involving robotic locomotor training, a novel technology, and standard activity-based training (Pan African Clinical Trial Registry (PACTR201608001647143)). Data were collected via in-depth interviews and analysed using thematic analysis.
Results:
Participants described several improvements in QoL, including enhanced functional independence; reduced secondary complications; and improved psychosocial and emotional well-being.
Conclusions:
The holistic approach to rehabilitation calls for the involvement of individuals’ views about what matters to them to inform clinical practice and to highlight the role that physical activity and the perceived successes play in shaping the lived experiences after SCI
The effect of cigarette smoking on the oral microbiota in a South African population using subgingival plaque samples
No full textDisturbances in the oral microbiota may be due to several mechanisms and factors, such as smoking. An imbalance in oral bacteria may result in changes to the innate immune system and the development of periodontal disease. This study aimed to investigate the distribution of oral microbiota in smokers and non-smokers in a South African population using subgingival plaque samples. From the 128 recruited participants, 57 were identified as smokers (serum cotinine: >15 ng/ml). Analysis of 16S rRNA gene sequencing demonstrated significant differences between the two groups with a reduced abundance of Actinobacteria in smokers. Fusobacterium and Campylobacter were found in higher abundance, while a lower abundance of Leptotrichia, Actinomyces, Corynebacterium, and Lautropia were observed. This study highlighted significant differences in the oral microbiota of smokers, indicating an abundance of anaerobic gram-negative bacteria. These findings suggest that smoking allows certain oral microorganisms to gain dominance, thereby predisposing individuals to periodontal disease development and progression
Leaf micromorphological assessment, chemical composition and anatomical responses of trachyandra ciliata (L.F) kunth to different degrees of salinity
No full textMany studies have examined the morphological and micromorphological responses of different halophytes to determine their salt tolerance mechanisms. However, few studies have focused on the South African edible halophytes. This study examined the leaf micromorphology, elemental composition, and anatomical responses using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) to examine salt tolerance levels in Trachyandra ciliata (L.F) Kunth. The treatments included varying sodium chloride (NaCl) concentrations: 50 mM, 100 mM, 150 mM and 200 mM, while control (0 mM) was watered with nutrient solution only. From the SEM micrographs, salt glands were observed protruding from the epidermis along the vascular system under low salinity and salt crystals appeared under higher concentrations, which makes this plant maintain cellular homeostasis under high salinity, and the plant can be classified as a recretohalophyte. Stomatal distribution, stomatal density and the number of open stomata decreased with increasing salinity. EDX revealed the presence of some important elements such as potassium, magnesium, phosphorus, calcium and more in the leaves. The results showed that increased salinity led to a decrease in the percentage composition of P, K and Ca2+, while Mg2+ was high under the control and low salinity (50 mM), decreased under 100 mM and increased again with increasing salinity. On the contrary, increasing salinity caused an increase in Na+ and Cl- in a stable manner. These findings reveal that T. ciliata acquires salt tolerance through changes to its leaf surface properties, osmotic adjustment, and the regulation of Na+ uptake and distribution in the leaves
Ethylene degradation via vacuum ultraviolet photolysis: nth-order kinetic model, energy consumption assessment, and a case study for ’Fuji’ apples under retail conditions
No full textEffective management of ethylene along the value chain is crucial to the regulation of fruit ripening and senescence to reduce postharvest losses. The objectives of this study were to, (i) investigate the degradation kinetics of ethylene using a vacuum ultraviolet (VUV) photolysis reactor at different light intensity (0.0005 mW/m2, 0.0014 mW/m2 and 0.0021 mW/m2) and relative humidity (RH) levels (20 % and 80 %), and (ii) evaluate the economic feasibility of the VUV photolysis system. Kinetic experiments were performed in batch mode with an initial ethylene concentration of 51 mg L−1. The reaction order and rate constant were determined by employing an nth-order kinetic model. Light intensity and RH significantly influenced the kinetic parameters and ethylene degradation (p < 0.05). At low light intensity, ethylene degradation followed a zero-order kinetic model, while at high intensity, it followed a fractional-order kinetic model. The developed kinetic models accurately predicted the experimental concentrations (R2 = 0.9955). The economic feasibility of the VUV photolysis system was assessed using electrical energy per order (EEO), which remained below 10 kW m-³ order−1, indicating energy efficiency and practical applicability. The chamber equipped with the VUV reactor successfully preserved apple quality (maintaining low TSS/TA ratio and delaying pH increase) during storage for 28 d at 15°C compared to the control. This foundational application of VUV photolysis in ethylene degradation offers promising prospects of upscaling for long-term storage investigation and industry applications
Assessment of the global Copernicus, NASADEM, ASTER and AW3D digital elevation models in Central and Southern Africa
No full textValidation studies of global Digital Elevation Models (DEMs) in the existing literature are limited by the diversity and spread of landscapes, terrain types considered and sparseness of groundtruth. Moreover, there are knowledge gaps on the accuracy variations in rugged and complex landscapes, and previous studies have often not relied on robust internal and external validation measures. Thus, there is still only partial understanding and limited perspective of the reliability and adequacy of global DEMs for several applications. In this study, we utilize a dense spread of LiDAR groundtruth to assess the vertical accuracies of four medium-resolution, readily available, free-access and global coverage 1 arc-second (30 m) DEMs: NASADEM, ASTER GDEM, Copernicus GLO-30, and ALOS World 3D (AW3D). The assessment is carried out at landscapes spread across Cape Town, Southern Africa (urban/industrial, agricultural, mountain, peninsula and grassland/shrubland) and forested national parks in Gabon, Central Africa (low-relief tropical rainforest and high-relief tropical rainforest). The statistical analysis is based on robust accuracy metrics that cater for normal and non-normal elevation error distribution, and error ranking. In Cape Town, Copernicus DEM generally had the least vertical error with an overall Mean Error (ME) of 0.82 m and Root Mean Square Error (RMSE) of 2.34 m while ASTER DEM had the poorest performance. However, ASTER GDEM and NASADEM performed better in the low-relief and high-relief tropical forests of Gabon. Generally, the DEM errors have a moderate to high positive correlation in forests, and a low to moderate positive correlation in mountains and urban areas. Copernicus DEM showed superior vertical accuracy in forests with less than 40% tree cover, while ASTER and NASADEM performed better in denser forests with tree cover greater than 70%. This study is a robust regional assessment of these global DEMs
Dimmable constant weight polar-coded non-orthogonal multiple access with orthogonal space-time block coding visible light communication systems
No full textThis study investigates the integration of dimmable constant weight polar-coded non orthogonal multiple access (NOMA) with orthogonal space-time block coding (OSTBC)
in visible light communication (VLC) systems over Nakagami-m fading environments. The
proposed scheme aims to enhance the reliability of VLC systems by reducing the outage
probability while accommodating dimming requirements. By allowing multiple users to uti lize the same time-frequency resources and adjust power levels based on individual channel
conditions, the system optimizes resource utilization. Additionally, the OSTBC method
provides effective communication among multiple users by leveraging transmit diversity
to improve system performance. The efficacy of the proposed approach is demonstrated
through analytical analysis and Monte Carlo simulations, showcasing superior outage
probability performance compared to conventional Alamouti-STBC schemes
Template-free conversion of rice husk silica into nano-zeolite X and its application in adsorption of heavy metal ions
No full textTemplate-free synthesis of nano-zeolite X at a high crystallization temperature and shorter time is attempted using rice husk ash silica, a low-cost and sustainable silica source, and the potential of the adsorbent for heavy metals is investigated. Rice husk ash silica and zeolites were characterized using XRF, XRD, SEM, FTIR, 29Si solid-state NMR, and N2 adsorption/desorption to determine the elemental composition, mineralogy, morphology, functional and framework structures, respectively. Static hydrothermal treatment (HT) at 100 °C for 6 h was established as the optimum synthesis condition for nano-zeolite X exhibiting particle size ~ 72 nm; pyramidal octahedral morphology with specific surface area and external surface area of 433 and 43 m2/g, respectively. The maximum adsorption capacity of NZX (qm) for Cu2+ and Ni2+ was 60.24 mg/g and 36.90 mg/g, respectively. The adsorption is spontaneous and thermodynamically feasible; it can best be described by the Langmuir isotherm and pseudo-second-order kinetic model
TCP Stratos for stratosphere based computing platforms
No full textStratosphere computing platforms (SCPs) benefit from free cooling but face challenges necessitating transmission control protocol (TCP) re-design. The redesign should be considered due to stratospheric gravity waves (SGWs), and sudden stratospheric warming (SSWs). SGWs, and SSWs disturb the wireless channel during SCPs packet communications. SCP packet transmission can be done using existing TCP variants at the expense of high packet loss as existing TCP variants do not consider SGWs, and SSWs. TCP variants designed for satellite links are not suitable as they do not explicitly consider the SSW, and SGW. Moreover, the use of SCPs in future internet is at a nascent stage. The presented research proposes a new TCP variant i.e., TCP Stratos. TCP Stratos incorporates a parameter transfer mechanism and comprises loss-based; and delay-based components. However, its window evolution considers the occurrence of SSWs, and SGWs. The performance benefit of the proposed approach is evaluated via MATLAB numerical simulation. MATLAB simulation has been used because of the consideration of the stratosphere. The modelling of the stratosphere in this case is challenging for conventional tools and frameworks. Performance evaluation shows that using TCP Stratos instead of existing TCP variants and improved TCP variants reduces the packet loss rate by an average of (7.1–23.1) % and (3.8–12.8) %, respectively. The throughput is enhanced by an average of (20.5–53)%, and (40.9–70)% when TCP Stratos is used instead of existing TCP variant and modified TCP variant, respectively
Performance analysis for predictive voltage stability monitoring using enhanced adaptive neuro-fuzzy expert system
No full textIntelligent voltage stability monitoring remains an essential feature of modern research into
secure operations of power system networks. This research developed an adaptive neuro-fuzzy expert
system (ANFIS)-based predictive model to validate the viability of two contemporary voltage stability
indices (VSIs) for intelligent voltage stability monitoring, especially at intricate loading and operation
points close to voltage collapse. The Novel Line Stability Index (NLSI) and Critical Boundary Index
are VSIs deployed extensively for steady-state voltage stability analysis, and thus, they are selected
for the predictive model implementation. Six essential power system operational parameters with
data values calculated at varying real and reactive loading levels are input features for ANFIS model
implementation. The model’s performance is evaluated using reliable statistical error performance
analysis in percentages (MAPE and RRMSEp) and regression analysis based on Pearson’s correlation
coefficient (R). The IEEE 14-bus and IEEE 118-bus test systems were used to evaluate the prediction
model over various network sizes and complexities and at varying clustering radii. The percentage
error analysis reveals that the ANFIS predictive model performed well with both VSIs, with CBI
performing comparatively better based on the comparative values of MAPE, RRMSEp, and R at
multiple simulation runs and clustering radii. Remarkably, CBI showed credible potential as a reliable
voltage stability indicator that can be adopted for real-time monitoring, particularly at loading levels
near the point of voltage instability