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•A novel parabolic trough receiver with toroidal rings is examined numerically.•Thermally efficient absorber exhibits a higher thermal efficiency of 69.32%.•Nu for the optimal ...absorber cases is 2.33 and 1.49 times higher than SAT.•Heat loss for the thermally efficient case is lower among all the examined cases.•Higher thermal enhancement index of 1.20 is seen with the energy efficient case.
The present work investigates the incorporation of internal toroidal rings in an absorber tube of a solar parabolic trough collector (SPTC) with an objective to enhance the thermal performance. To produce substantial effect on the heat transfer rate, nine different cases of absorbers have been considered. The fully developed turbulent heat transfer characteristics of the absorber tube have been numerically studied and validated under varying inlet temperatures and flow rate of the heat transfer fluid (HTF). Realizable k-ε two-equation turbulence model with enhanced wall treatment has been used with ANSYS FLUENT 15 commercial codes. The influence of toroidal rings on heat transfer and fluid flow are evaluated and presented. The absorber with toroidal ring having a diameter ratio (H) of 0.88 and pitch size (p) of 2d is the thermally efficient optimal case. While the absorber with H = 0.92 and p = 2d is the energy efficient optimal case, with H being the ratio of inner to outer diameter of the toroidal ring and 2d being the distance between the adjacent rings, which is equal to two times the inner diameter of the absorber tube. When the inlet temperature of HTF is 600 K, the increase in efficiency for the thermally efficient and energy efficient optimal case are found to be 3.74% and 1.88%, while the increase in Nusselt number is found to be 2.33 and 1.49 times higher than the smooth absorber tube (SAT), respectively.
The increased complexity and heterogeneity of emerging 5G and B5G wireless networks will require a paradigm shift from traditional resource allocation mechanisms. Deep learning (DL) is a powerful ...tool where a multi-layer neural network can be trained to model a resource management algorithm using network data.Therefore, resource allocation decisions can be obtained without intensive online computations which would be required otherwise for the solution of resource allocation problems. In this context, this article focuses on the application of DL to obtain solutions for the radio resource allocation problems in multi-cell networks. Starting with a brief overview of a DNN as a DL model, relevant DNN architectures and the data training procedure, we provide an overview of existing state-of-the-art applying DL in the context of radio resource allocation. A qualitative comparison is provided in terms of their objectives, inputs/outputs, learning and data training methods. Then, we present a supervised DL model to solve the sub-band and power allocation problem in a multi-cell network. Using the data generated by a genetic algorithm, we first train the model and then test the accuracy of the proposed model in predicting the resource allocation solutions. Simulation results show that the trained DL model is able to provide the desired optimal solution 86.3 percent of the time.
Solar photovoltaic (PV) energy has witnessed double-digit growth in the past decade. The penetration of PV systems as distributed generators in low-voltage grids has also seen significant attention. ...In addition, the need for higher overall grid efficiency and reliability has boosted the interest in the microgrid concept. High-efficiency PV-based microgrids require maximum power point tracking (MPPT) controllers to maximize the harvested energy due to the nonlinearity in PV module characteristics. Perturb and observe (P&O) techniques, although thoroughly investigated in previous research, still suffer from several disadvantages, such as sustained oscillation around the MPP, fast tracking versus oscillation tradeoffs, and user predefined constants. In this paper, a modified P&O MPPT technique, applicable for PV systems, is presented. The proposed technique achieves: first, adaptive tracking; second, no steady-state oscillations around the MPP; and lastly, no need for predefined system-dependent constants, hence provides a generic design core. A design example is presented by experimental implementation of the proposed technique. Practical results for the implemented setup at different irradiance levels are illustrated to validate the proposed technique.
The use of fat grafting is being widely used for different indications one of which is wound healing. In this study we compare the use of autologous fat grafting (AFG) as a novel indication in acute ...burn wounds healing and burn scarring to the conventional methods of burn wound management both clinically and histologically. Several small observational studies demonstrated the effect of the AFG in healing of chronic wounds, different vascular ulcers or effect on scars yet no randomized controlled trial is available to compare its role with conventional methods.
The study was a prospective, open-label single center, randomized control clinical trial included 100 patients with superficial and deep dermal burns from March 2019 to March 2020 randomized to AFG protocol consisted of a single injection of autologous fat grafting then dressed with nano fat (Group A) or conventional methods of serial dressings with 1% silver sulphadiazine or other topical agents (Group B). Inclusion criteria included newly admitted burn patients with affected total body surface area (TBSA) (10%-25%) while exclusion criteria included burns patients with affected TBSA of< 10% or> 25%, or loss of subcutaneous fat, fascia, muscles and bones, inhalational burn, and burns in genitalia, perineum and peri-anal areas and co-morbidity(ies) that might affect wound healing or eligibility for anaesthesia and surgery. Also, results were confirmed by histological analysis for samples from both groups by light microscopic examination, and the nano-fat was subjected to flow cytometric analysis of the cluster of differentiation (CD) markers of mesenchymal stem cells markers CD 90, CD44, CD45, CD 73, and CD 34. (ClinicalTrials.gov Identifier: NCT03791710) RESULTS: We found a significant reduction in total hospital stay days (p = <0.001), less further skin grafting (p = 0.003), less contracture formation (p = <0.002) while scar texture improved (p = <0.001) in group A compared to group B. Flow cytometric analysis documented that the nano-fat was positive to CD 90, 73, 44, 45 and 34.
In a comparison between AFG protocol to the conventional methods in the treatment of acute burn wounds, AFG protocol was associated with significant clinical improvement in the form of lower hospital stay time, lower incidence of scaring or contracture and lower skin grafting use which was confirmed by serial photographic and histological assessment.
At present, anti-virulence drugs are being considered as potential therapeutic alternatives and/or adjuvants to currently failing antibiotics. These drugs do not kill bacteria but inhibit virulence ...factors essential for establishing infection and pathogenesis through targeting non-essential metabolic pathways reducing the selective pressure to develop resistance. We investigated the effect of naturally isolated plant compounds on the repression of the quorum sensing (QS) system which is linked to virulence/pathogenicity in
Pseudomonas aeruginosa
. Our results show that
trans
-cinnamaldehyde (CA) and salicylic acid (SA) significantly inhibit expression of QS regulatory and virulence genes in
P. aeruginosa
PAO1 at sub-inhibitory levels without any bactericidal effect. CA effectively downregulated both the
las
and
rhl
QS systems with
lasI
and
lasR
levels inhibited by 13- and 7-fold respectively compared to 3- and 2-fold reductions with SA treatment, during the stationary growth phase. The QS inhibitors (QSI) also reduced the production of extracellular virulence factors with CA reducing protease, elastase and pyocyanin by 65%, 22% and 32%, respectively. The QSIs significantly reduced biofilm formation and concomitantly with repressed rhamnolipid gene expression, only trace amount of extracellular rhamnolipids were detected. The QSIs did not completely inhibit virulence factor expression and production but their administration significantly lowered the virulence phenotypes at both the transcriptional and extracellular levels. This study shows the significant inhibitory effect of natural plant-derived compounds on the repression of QS systems in
P. aeruginosa
.
Landfilling is one of the most common waste management methods employed in all countries alike, irrespective of their developmental status. The most commonly used types of landfills are (a) municipal ...solid waste landfill, (b) industrial waste landfill, and (c) hazardous waste landfill. There is, also, an emerging landfill type called “green waste landfill” that is, occasionally, being used. Most landfills, including those discussed in this review article, are controlled and engineered establishments, wherein the waste ought to abide with certain regulations regarding their quality and quantity. However, illegal and uncontrolled “landfills” (mostly known as open dumpsites) are, unfortunately, prevalent in many developing countries. Due to the widespread use of landfilling, even as of today, it is imperative to examine any environmental- and/or health-related issues that have emerged. The present study seeks to determine the environmental pollution and health effects associated with waste landfilling by adopting a desk review design. It is revealed that landfilling is associated with various environmental pollution problems, namely, (a) underground water pollution due to the leaching of organic, inorganic, and various other substances of concern (SoC) contained in the waste, (b) air pollution due to suspension of particles, (c) odor pollution from the deposition of municipal solid waste (MSW), and (d) even marine pollution from any potential run-offs. Furthermore, health impacts may occur through the pollution of the underground water and the emissions of gases, leading to carcinogenic and non-carcinogenic effects of the exposed population living in their vicinity.
Graphical abstract
Epidemiological studies suggest that the severity of periodontitis is higher in people with diabetes than in healthy individuals. Insulin resistance might play a crucial role in the pathogenesis of ...multiple diabetic complications and is reportedly induced in the gingiva of rodents with type 2 diabetes; however, the molecular mechanisms underlying the pathogenesis of diabetes-related periodontitis remain unclear. Therefore, we aimed to investigate whether endothelial insulin resistance in the gingiva may contribute to the pathogenesis of periodontitis as well as elucidate its underlying molecular mechanisms. We demonstrated that insulin treatment downregulated lipopolysaccharide (LPS)–induced or tumor necrosis factor α (TNFα)–induced VCAM1 expression in endothelial cells (ECs) via the PI3K/Akt activating pathway, resulting in reduced cellular adhesion between ECs and leukocytes. Hyperglycemia-induced selective insulin resistance in ECs diminished the effect of insulin on LPS- or TNFα-stimulated VCAM1 expression. Vascular endothelial cell–specific insulin receptor knockout (VEIRKO) mice exhibited selective inhibition of the PI3K/Akt pathway in the gingiva and advanced experimental periodontitis-induced alveolar bone loss via upregulation of Vcam1, Tnfα, Mcp-1, Rankl, and neutrophil migration into the gingiva compared with that in the wild-type (WT) mice despite being free from diabetes. We also observed that insulin-mediated activation of FoxO1, a downstream target of Akt, was suppressed in the gingiva of VEIRKO and high-fat diet (HFD)–fed mice, hyperglycemia-treated ECs, and primary ECs from VEIRKO. Further analysis using ECs transfected with intact and mutated FoxO1, with mutations at 3 insulin-mediated phosphorylation sites (T24A, S256D, S316A), suggested that insulin-mediated regulation of VCAM1 expression and cellular adhesion of ECs with leukocytes was attenuated by mutated FoxO1 overexpression. These results suggest that insulin resistance in ECs may contribute to the progression of periodontitis via dysregulated VCAM1 expression and cellular adhesion with leukocytes, resulting from reduced activation of the PI3K/Akt/FoxO1 axis.
Hypertension (HTN) is a primary global health concern. Moreover, according to the 2010 Global Burden of Disease, hypertension accounted for roughly a quarter of cardiovascular disease fatalities and ...1.9 percent of all deaths in Saudi Arabia in 2010. Also, hypertension is a significant risk factor for cardiovascular disease, morbidity, and mortality. However, assessing blood pressure (BP) and preventing hypertension among children and adolescents has become a global priority. This study aims to determine the prevalence of hypertension among children in the Jazan region of Saudi Arabia. Also, to determine the common risk factors associated with pediatric hypertension. We conducted this cross-sectional study among boys and girls aged 6-14 years visiting Al-Rashid Mall, one of the two main malls in Jazan city, the capital of Jazan region, Saudi Arabia, between November 2021 and January 2022. We included children willing to participate in the study after obtaining their parents' consent and children's assent. We used a standardized questionnaire to interview the parents to collect the children's data. We also measured the children's resting BP. Then we classified the measurements according to the updated International Pediatric Hypertension Association (IPHA) chart. We also measured the height and weight of the children and calculated their BMI. We used SPSS version 25 for the data entry and analysis. Our results showed that the prevalence of hypertension and prehypertension was insignificantly higher in females (11.84% and 12.65%) compared to males (11.52% and 11.52%), respectively. Our participants' main associated factors with prehypertension and hypertension were overweight, obesity, and family income. Pediatric hypertension and prehypertension were highly prevalent in Jazan region. Therefore, being overweight and obese should be considered risk factors for pediatric hypertension. Our study emphasizes the need for early intervention to prevent pediatric HTN, particularly among overweight and obese children.
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