Spatio-temporal analysis of aerosol concentration over Saudi Arabia using satellite remote sensing techniques

Aerosols are a principal factor in altering climatic dynamics both at regional and global scales. Saudi Arabia is highly affected by aerosols particulates mainly due to the frequent sand and dust storm events in the region. In this context, this study examined Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue (DB) Aerosol Optical Depth (AOD) variability both from Terra and Aqua satellites and its relationship with temperature for the period 2002-2007.A comparison between Terra and Aqua DB AOD products were also made in this study. The annual mean AOD analysis based on Terra and Aqua showed a decreasing and increasing trend respectively. Results of the study also showed that the temperature had a strong correlation with Terra DB AOD (r =0.79) than Aqua DB AOD (r =0.68). Overall, DB algorithm was found to be well enough for the assessment of aerosol variability to be conducted over Saudi Arabia

A clinical and ultrastructural investigation of the cornea in keratoconus

Keratoconus is a non-inflammatory corneal disease that progressively causes topographical alteration of the cornea as a result of thinning, and consequently leads to impaired vision. In this thesis, the clinical studies are showed that the incidence rate and severity of keratoconus in Asir province, Saudi Arabia is high with an early onset and more rapid progress to the severe disease stage at a young age compared to other countries. The result also showed that the disease required different contact lens designs to be available in the clinics and the selection of initial back optic zone radius for multiple contact lens designs should be based in the steepest keratometric reading in early stage, and on average keratometric reading on moderate and advanced stages. However, regardless of the stage of disease, tricurve contact lens design should be selected based on average keratometric reading. Ultrastructure investigation of the anterior surface of Bowman's layer using different microscopes revealed that the changes are not limited to the apical cone only, but extend to the periphery of the cornea especially in the advances stage of keratoconus. Also, although the topographical map is usually used in trephination, it was found that the topographical features alone failed to indicate the full extent of the progress of keratoconus towards the corneal periphery. Data from transmission electron microscopy and high-angle X-ray diffraction suggest that the structural abnormalities in the stromal fibrillar matrix might be influential underlying reasons for topographic changes in the keratoconic-like changes of SPARC-null and JKC mice

Seasonal Aerosol Optical Depth (AOD) variability using satellite data and its comparison over Saudi Arabia for the period 2002–2013

This study analyzes the spatiotemporal variations of seasonal Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue (DB) AOD at 550 nm from the Aqua satellite over Saudi Arabia for the period 2002‒2013. Satellite retrieved AOD is also compared with AERONET AOD over the Solar Village and KAUST station. The result of the seasonal AOD spatial distribution shows that the peak AOD value of 0.6 is observed over Hafr Al Batin, Riyadh, and the Rub Al Khali desert during spring, whereas the Gizan area shows the peak AOD during summer. In contrast, the autumn shows the peak AOD value of 0.5 over Dhahran and in the proximity of Jeddah, whereas Hafr Al Batin, Al Khafji, Al Jubail, and the Rub Al Khali desert show the peak AOD value of 0.4 in winter. Regression analysis shows the AOD increasing trends during spring, summer, and autumn (except for winter) over the entire Saudi Arabia. Over the Solar Village, the AOD increasing trends are also noted during spring and summer, whereas autumn and winter display the AOD decreasing trends. The AOD increasing trends are displayed in all seasons over KAUST. Hence, the AOD increasing/decreasing trends indicate that the number of dust storms either increases or decreases over these regions. Over the Solar Village, the correlation values for MODIS DB AOD versus AERONET AOD are 0.77 (spring), 0.62 (summer), 0.65 (autumn), and 0.75 (winter). Likewise, over KAUST, the correlation values for the same pairing are 0.85 (spring), 0.71 (summer), 0.81 (autumn), and 0.89 (winter). The incorrect aerosol model selection and imperfect surface reflectance calculation are responsible for reducing the correlation. Therefore, this study recommends that the DB algorithm can be used effectively to detect AOD over Saudi Arabia, which will further help to improve the MODIS DB AOD product utilizing the next version of the algorithm

Exploring the Knowledge, Attitude and Practice Regarding Hepatitis B Infection Among Dental Students in Saudi Arabia: A Cross-Sectional Study

BACKGROUND: Hepatitis B infection is a universal health problem. Worldwide, 5% of health-care-related injections continued unsafe. Dentist considers being at high-risk group for cross infection. Therefore, their knowledge and practice towards Hepatitis B virus (HBV) positive patients should be at an optimal level. AIM: The current study is aimed to evaluate and comparison of the knowledge, attitude and practice of Saudi dental students and interns towards HBV infection. METHODS: A self-explanatory questionnaire comprising of 16 questions was designed to assess and compare students’ knowledge, attitude and risk perception regarding hepatitis B infection among dental students across Saudi Arabia. RESULTS: The response rate was 91.6% the overall knowledge of the participants was poor. The attitude was fair, with the female show a significant difference in attitude and practice (P-value < 0.05). The overall practice was good, 78.1% was vaccinated against HBV, and 73.2% stated that they regularly use personal protection equipment. The higher levels show a good attitude and practice compared with the lower levels; the difference was significant (P value < 0.05). CONCLUSION: The overall knowledge was below average, continuous health education courses are mandatory

Optimization of carboxymethyl cellulose-gum Arab-based hydrogel beads for anticancer drugs delivery

Response surface methodology was successfully utilized to optimize the amounts of carboxymethyl cellulose (CMC) and gum Arab (GA) to fabricate hydrogel beads for the delivery of anticancer drugs. Drug encapsulation efficiency process (%DEE) and cumulative release (%R8h) of hydrogel beads were investigated with different amounts of CMC and GA with Fe (III) cross-linker. The numerical validation resulted in an optimized nanocomposite of CMC (99.61 mg) and GA (77.84 mg) with a DEE of 55.70 ± 2.15 % and R8h of 44.78 ± 0.27 %. The characterization approaches indicated the successful formation of this nanocomposite. The swelling behavior of the beads was triggered by pH change, and the drug release profile showed prolonged sustainable release that followed the Higuchi model with a non-Fickian mechanism. This nanocomposite could be a promising nanocarrier for drug loading and its controlled delivery

Dynamic Resource Management in Integrated NOMA Terrestrial-Satellite Networks using Multi-Agent Reinforcement Learning

This study introduces a resource allocation framework for integrated satellite-terrestrial networks to address these challenges. The framework leverages local cache pool deployments and non-orthogonal multiple access (NOMA) to reduce time delays and improve energy efficiency. Our proposed approach utilizes a multi-agent enabled deep deterministic policy gradient algorithm (MADDPG) to optimize user association, cache design, and transmission power control, resulting in enhanced energy efficiency. The approach comprises two phases: User Association and Power Control, where users are treated as agents, and Cache Optimization, where the satellite (Bs) is considered the agent. Through extensive simulations, we demonstrate that our approach surpasses conventional single-agent deep reinforcement learning algorithms in addressing cache design and resource allocation challenges in integrated terrestrial-satellite networks. Specifically, our proposed approach achieves significantly higher energy efficiency and reduced time delays compared to existing methods.Comment: 16, 1

Enrofloxacin and Sulfamethoxazole Sorption on Carbonized Leonardite: Kinetics, Isotherms, Influential Effects, and Antibacterial Activity toward \u3ci\u3eS. aureus\u3c/i\u3e ATCC 25923

Excessive antibiotic use in veterinary applications has resulted in water contamination and potentially poses a serious threat to aquatic environments and human health. The objective of the current study was to quantify carbonized leonardite (cLND) adsorption capabilities to remove sulfamethoxazole (SMX)- and enrofloxacin (ENR)-contaminated water and to determine the microbial activity of ENR residuals on cLND following adsorption. The cLND samples prepared at 450oC and 850oC (cLND450 and cLND550, respectively) were evaluated for structural and physical characteristics and adsorption capabilities based on adsorption kinetics and isotherm studies. The low pyrolysis temperature of cLND resulted in a heterogeneous surface that was abundant in both hydrophobic and hydrophilic functional groups. SMX and ENR adsorption were best described using a pseudo-second-order rate expression. The SMX and ENR adsorption equilibrium data on cLND450 and cLND550 revealed their better compliance with a Langmuir isotherm than with four other models based on 2.3-fold higher values of qmENR than qmSMX. Under the presence of the environmental interference, the electrostatic interaction was the main contributing factor to the adsorption capability. Microbial activity experiments based on the growth of Staphylococcus aureus ATCC 25923 revealed that cLND could successfully adsorb and subsequently retain the adsorbed antibiotic on the cLND surface. This study demonstrated the potential of cLND550 as a suitable low-cost adsorbent for the highly efficient removal of antibiotics from water

Pseudocapacitive performance of phenothiazine functionalized graphene aerogel

This study utilizes light adsorbing molecule, phenothiazine (PTZ) to reduce graphene oxide (GO) and functionalize into PTZ-rGO aerogel (PTZ-rGO). The UV excited PTZ reduces GO via electron transfer while PTZ is simultaneously oxidized and functionalized onto rGO to produce PTZ-rGO aerogel. The optimum incorporation of PTZ on rGO sheets renders good electrochemical active surface area of 495.71 m2 g−1 and enhances the diffusion behavior up to 41.92%. This pseudocapacitive effect and the excellent surface property provide promising charge storage results of 235.5 F g−1 at 0.5 A g−1. Furthermore, the stable charge-discharge cycles with 92% capacitance retention after 10,000 cycles render it an excellent electrode material for supercapacitor fabrication