Sultan Qaboos University Scientific Journals
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Performance of Mineral Oil Based Multi-Walled Carbon Nanotubes Nanolubricant in Vapor Compression Refrigeration System: An Experimental Study: An Experimental Study
No full textExtensive research has been carried out in order to design a refrigeration system that is efficient and consumes less power. Several researchers have explored various techniques to decrease the power usage of compressors and increase the coefficient of performance (COP) of refrigeration systems by utilizing nanoparticles. The remarkable properties of nanoparticles, including their exceptional thermo-physical and tribological characteristics, have made their usage in a variety of thermal applications. This study investigated the performance of a hydrocarbon blend refrigerant also known as Liquefied Petroleum Gas (LPG), mixed with Multi-Walled Carbon Nanotube (MWCNT) nanolubricant made from mineral oil (MO) at different concentrations (0.2, 0.4, and 0.6 g/L), to replace the conventional working fluid R134a/Polyolester (POE) oil. The overall performance of the system was observed by evaluating different parameters such as; pressure ratio, compressor energy consumption (EC), refrigeration effect (RE) and COP. The results revealed that by using 0.4 g/L nanolubricant with LPG reduced the pressure ratio and compressor’s energy consumption by 54.3% and 25% respectively, and also improved the COP by 25% compared to R134/POE. The ideal concentration for nanolubricant among all the working fluids was found to be 0.4 g/L
Analysis and Characterization of TIO2 Nanoparticle Effect on Aluminum Matrix Nanocomposites by Stir Casting
Full text linkThe objective of this study was to use stir casting to create aluminum matrix nanocomposites with a uniform dispersion of TiO2 nanoparticles to evaluate their effect on the performance of aluminum-based products. Microstructural analysis significantly reduced the grain size, with an average drop of 18.2%. This suggests that the TiO2 nanoparticles affect the mineral matrix, which improves the mechanical properties. With the incorporation of TiO2 particles, the results showed improvements in stiffness (6.97%), nominal stress (27.92%), actual failure stress (25.6%), and ultimate stress (26.1%). Outperforming commercially pure aluminum, the mechanical properties of the resulting nanocomposites were significantly improved by adding TiO2 nanoparticles into the aluminum matrix. Microstructural and X-ray diffraction (XRD) studies confirmed the beneficial effects of the addition of nanoparticles
INFLUENCE OF BACILLUS PUMILUS ON THE PLASTICITY OF TREATED LATERITIC SOIL
Full text linkThe effect of Bacillus pumilus (B. pumilus) on the improvement potential of some selected geotechnical properties of lateritic soil was studied. Air-dried soils were cured in paced Bacillus pumilus suspensions between 0 and 2.4 × 109 cells/ml. Cured test samples adopted mix ratios of 50% B. pumilus / 50 % cementation reagent(50 % B – 50 % C) for sample A and 25% B. pumilus / 75 % cementation reagent(25% B – 75% C), for sample B, all conforming to the liquid limit of the soil. The geotechnical properties of the lateritic soil showed different levels of improvement with increasing B. pumilus suspension densities. The specific gravity generally diminished with rise in B. pumilus suspension from 2.55 for the natural soil to 2.33 and 2.26 at 2.4 × 109 cells/ml for samples A and B, respectively. The cation exchange capacity (CEC) decreased from 26.6Cmol/kg for the natural soil to 8.7Cmol/kg at B. pumilus suspension of 1.8 × 109 cells/ml. The Atterberg Limits of lateritic soil specifically, plasticity index (PI) decreased from 19.0% and 29.1% for the natural and control lateritic soil to values of 6.2 and 8.9 % for samples A (50 % B – 50 % C) and B (25% B – 75% C), respectively, at optimal B. pumilus suspension density of 2.4 × 109 cells/ml, Sample B (25 % B – 75% C) recorded a better improvement in terms of the plasticity of the treated soil
Tracking Stray Camels Crossing the Roads to Prevent Vehicle Accidents in Oman
Full text linkThe work presented in this paper addresses the problem of vehicle accidents due to stray camels crossing the roads by notifying the drivers about camels’ existence and location. Subsequently, the drivers can take precautionary measures to prevent collisions with camels. This is achieved by developing a system consisting of two parts. The first part is a bracelet tied to the camel's neck, and the second is the mobile application installed on the driver's mobile device. Hence, this proposed work aims to prevent road accidents in Oman due to stray camels moving freely on the roads and achieving safer travel during the day and night
Gated Recurrent Unit for Load Forecasting of Water Pumping Stations in Jebel Akhdar
Full text linkThe relationship between water demand and electrical power consumption is critical as water transmission systems necessitate considerable amounts of energy. Accurate load forecasting for water pumping stations can improve the proper administration of energy, reduce inefficiency, and improve profitability. The application of contemporary deep learning techniques can significantly optimize energy consumption, save expenditures, and promote sustainable development in the context of water pumping stations. Moreover, precise load forecasting is essential for the proper functioning and energy management of water pumping stations, especially in areas with intricate topographical circumstances. Hence, this research utilizes Gated Recurrent Units (GRUs) to forecast the load demands of water pumping stations in Jebel Akhdar. The suggested model is specifically intended to capture the temporal dependencies and non-linear patterns that are inherent in the load demand data of the water pumping stations. In this regard, GRUs excel in their ability to dynamically update the hidden state, allowing them to capture complex temporal patterns accurately. Therefore, this study offers specific insights and solutions that may be used to comparable places characterized by intricate time-series variables. The approach provides superior prediction accuracy compared to standard forecasting methods by using historical load data. The findings of this work illustrate valuable insights for utility regulators to optimize energy usage and ensure sustainable water delivery
A Quick and Comprehensive Method for Determining Static ATC with NRS and VFT
Full text linkElectricity market players prioritize available transfer capability (ATC) as an attractive solution. Market participants can gain a financial advantage through accurate and fast ATC solutions. In order to provide a suitable and valuable solution, we use differential load flow equations. A dynamic system's entire time-domain trajectory can be solved by this method, along with a fictional time-domain differential equation. This article uses Newton-Raphson-Seydel instead of Newton-Raphson, which can also be used to determine voltage stability. A variable frequency transformer (VFT) was used in this study to increase and control transmission power. A 50% time saving on small systems was achieved with the proposed method, which was applied to seven different systems. In addition, it performed better on large systems by more than 90%. This proposal for static ATC presents promising results and can be applied to online applications
Incidence of Urinary Tract Infections, Etiological Agents, and Antibiotic Susceptibility Among Pregnant and Non-Pregnant Women in Amedi Region, Iraq
Full text linkUrinary tract infection is a bacterial infection caused by bacteria from the digestive tract entering the urinary tract. It is more prevalent in women and remains the most common bacterial infection in humans. The study aimed to assess the prevalence of urinary tract infections (UTIs) in pregnant women, identify and diagnose uropathogenic bacteria, and examine the antibiotic susceptibility of the isolated bacteria. A total of 283 urine specimens were collected from pregnant and non-pregnant females of different ages who visited Amedi hospital between October 2020 and January 2021. The samples were cultured and incubated on Blood agar and MacConkey agar plates for 24 hours at 37°C. Bacterial isolates were identified and their antibiotic sensitivity was assessed using the Vitek-2 method. The study found a total UTI rate of 42.4% (120/283), with higher rates in pregnant patients (58.3%) compared to non-pregnant patients (41.7%). Among 120 positive urine cultures, bacterial isolates were identified in 92.5% (111/120), with Gram-positive bacteria being more prevalent (51.4%) than Gram-negative (48.6%). The most common Gram-negative bacteria was Escherichia coli (29.7%), while Gram-positive bacteria included Enterococcus faecalis, Staphylococcus haemolyticus, and Streptococcus agalactiae (each 12.6%; 14/111). The rate of fungal positive cultures (Candida spp.) was 7.5%. Gram-negative isolates showed high sensitivity to tigecycline (99.0%) and ertapenem (80.6%), but low sensitivity to ampicillin (2.7%) and cefuroxime (16.1%). Gram-positive isolates were highly sensitive to linezolid (98.7%) and tigecycline (98.5%). The findings of this study are valuable for understanding the nature of urinary tract infections (UTIs) and guiding appropriate treatment, leading to a reduction in the misuse of antibiotics.
Keywords: Urinary tract infection; Pregnancy; Antibiogram; Uropathogenic bacteria; Iraq
The Class I Histone Deacetylase Inhibitor as a Potent Therapeutic Target for Treating Glioblastoma and Mocetinostat as a Novel Inhibitor in the Induction Death of Cancer Cells
Full text linkEpigenetic abnormality is one of the hallmarks of glioblastoma cancer cells. Histone deacetylase (HDAC) modification has a crucial role in epigenetic abnormality, which results in the initiation and progression of glioblastoma cancer cells. The selective HDAC inhibitors are well-known epigenetic regulators and promising anti-cancer agents that target specific HDAC enzymes and inhibit the proliferation of many cancer cells. Selective HDAC inhibitors isoform provides a high efficacy as chemotherapy in inhibiting cancer confirmation compared to non-selective HDAC inhibitors. Additionally, selective HDAC inhibitors suppress Class -I HDAC1, HDAC2, HDAC3, and HDAC11. HDAC class I inhibitors induce apoptosis, differentiation, autophagic death cells, and reactive oxygen species (ROS)- induced cell death, inhibit cell migration, invasion, and angiogenesis in cancer cells, while the normal cells showed more resistance to HDAC class I inhibitors. Mocetinostat (MGCD0103), a benzamide histone deacetylase, is a potent anti-cancer therapy for the treatment of several cancer cell lines and induction of autophagy. It has been approved by The Food and Drug Administration (FDA) for the treatment of Hodgkin lymphoma (HL) cell lines. MGCD0103 is a synthesized and selective HDAC inhibitor that has vigorous inhibitory activity against Class-I and IV HDAC. MGCD0103 is well tolerated and has favorable pharmacokinetic properties, pharmacodynamic profile, and fast absorption within 1 hour after oral administration, long elimination half-life, and sustained HDAC inhibition. Therefore, MGCD0103 is expected to be a promising anti-cancer drug for treating several types of human cancer cells.
Keywords: MGCD0103; Apoptosis; Differentiation; Gliblastoma; HDAC; inhibitors
Supercontinuum Generation by Controlling Pitch in Photonic Crystal Fibers
Full text linkThe influence of varying the distance between air holes (pitch) on the geography of solitone propagation through a photonic crystal fiber has been tested. The study depends on the Split-Step Fourier method and the results quantified using MATLAB. The first-order solitone was tested with the change in pitch, and it was found that there is a clear decay in the amplitude of the resulting pulse with an increase in pitch. When increasing the pitch in the case of second-order solitons, it was noticed that the pulse would split into multiple-order solitons down to higher-order solitons with the increase in pitch. In the case of third-order solitons, solitonic fission leads to the supercontinuum generation with increasing the pitch, where the supercontinuum generation was reached in this way depending on a very small energy source compared to the high energies used to generate this type of spectrum by the previous methods. In this study, I observed that when the pitch values increased in the third-order soliton, this result led to the use of supercontinuum generation (ScG) which has many applications such as medical and industrial applications and has an important role in modern communication systems.
Keywords: Photonic Crystal Fiber, Split-Step Fourier, Soliton Pulse, Pitch, Supercontinuum Generation
Impact of Selected Adsorbent Functional Groups on Chromium Sorption Capacities In An Effluent Treatment: A DFT Study
Full text linkCommunities are often exposed to high health risks via the presence of most heavy metals in water bodies used by their residents. Chromium, an abundant heavy metal in industrial effluents, contaminates our environment and water sources, endangering human and animal consumption. Designing materials for Cr removal from potential effluent discharges is crucial. Bio-based sorbents have been explored, but the role of functional groups remains unclear. This research investigates the influence of functional groups in removing dissolved chromium heavy metals to enhance water quality. In this study, we look at how well functional groups like carboxylate, carbonyl, nitrile, aldehyde, alcohol, and carboxylic acid bind to Cr (III) metal. We look at stable Cr metal cluster configurations using Spartan software and density functional theory (DFT) for quantum chemical calculations. We measure energies and thermodynamic properties during interactions. Our findings demonstrate that sorbents with carbonyl and carboxylate groups exhibit high sensitivity to Cr, making them effective for removal. The relative adsorption energies align with experimental results. This study confirms the potential of computational methods to predict sorbents' selectivity in removing various heavy metals from water, offering a promising avenue for water treatment and environmental protection