Numerical and experimental development of an efficient adsorption desalination and cooling system

In this Ph.D. thesis, different methods for enhancing the performace of heat powered adsorption system for water desalination and cooling are investigated through numerical and experimental works. These enhancement methods include: (i) optimizing the geometric design of the adsorber bed heat exchangers for both packing or coating with the adsorbent material , (ii) determining the best method of connecting the heat exchanger modules of the adsorber bed and the best vapor gap between them to reduce the mass transfer resistance, (iii) using metal-organic framework (MOF) adsorbent materials namely aluminium fumarate and a newly developed composite zirconium fumarate (MOF-801) / graphene to replace the conventional adsorbent materials, (iv) reducing the dead volume in the condenser and evaporator chambers to enhance the compactness of the adsorption system and (v) integrating the adsorption system with different desalination technology to increase the water recovery, and reduce the specific energy consumption. After optimizing the geometrical design of the heat exchanger in the adsorber bed, a comparative study between a packed rectangular-finned tube and a coated wire-finned tube is conducted. Results showed that the coated wire-finned tube enhanced the adsorption system specific daily water production (SDWP) and specific cooling power (SCP) by 82% compared to the packed rectangular finned tube, while it lowered the system coefficient of performance (COP) by 52%. In terms of the specific volumetric daily water production (SVDWP), the adsorption system with coated wire-finned adsorber beds has SVDWP lower than the system with packed one by 21%. Integrating the adsorption system with a Batch Reverse Osmosis (BRO) desalination system using packed rectangular-finned tube adsorption system and a wide range of water salinity, it is found that the water recovery can be increased to 96.9% and 65.3% when brackish water and seawater are fed to the hybrid system respectively. Finally, using a newly developed composite zirconium MOF (MOF-801) material with graphene nanoplatelets enhanced the SDWP and SCP by 40% due to its higher thermal conductivity and faster kinetics compared to the neat MOF

Bone mass in Saudi women aged 20–40 years : the association with obesity and vitamin D deficiency

Summary: This study describes that low bone density is prevalent in premenopausal Saudi women, especially women of normal weight and vitamin D deficiency. Although BMD is higher in obese young women, this may not be beneficial later in life in conjunction with persistent vitamin D deficiency. Introduction: Not attaining peak bone mass is one crucial factor contributing to the risk of developing osteoporosis and suffering fractures in later life. The objectives of this study were to describe the normal range of bone mineral density (BMD) and bone mineral content (BMC) in premenopausal Saudi women in relation to obesity and vitamin D insufficiency. Methods: A cross-sectional study involving 312 healthy Saudi women aged 20–40. All women were clinically examined. BMD (g/cm2) and BMC (g) assessed at total body (TB), femoral neck (FN) and lumbar spine (LS) were performed using dual-energy X-ray absorptiometry (DXA). Obesity was defined as BMI ≥ 30 kg/m2 and vitamin D deficiency defined as 25(OH)D < 50 nmol/L. Results: Almost half of the studied women were obese, and the majority (86.2%) were deficient in vitamin D. Mean BMD in TB 1.060 ± 0.091, FN 0.918 ± 0.153 and LS 1.118 ± 0.123 g/cm2, while TB-BMC 2077 ± 272 g. When classified by BMI, the proportion with low bone density was 2–3 times higher among the normal weight compared to the obese women, p < 0.001. In the cohort overall, ~ 19% of these young premenopausal women had osteopenia or osteoporosis at the femoral neck, but 26% in normal weight, vitamin D deficient women. Conclusion: This study shows low bone density in premenopausal Saudi women, particularly those with normal weight. While obesity appears to confer some protection against vitamin D deficiency at this age, this is assumed to change in later life

Impact of the Syrian conflict and forced displacement on respiratory health: an analysis of primary data from a humanitarian organisation

Background Despite a decade of conflict, there has been little exploration of respiratory health in Syria, notwithstanding the known impacts of conflict on lung health. Our aim is to explore the burden and trends of respiratory consultations in Syrian American Medical Society (SAMS) facilities in northwest Syria through an ecological analysis.Methods We performed a retrospective review of routinely collected data relating to respiratory presentations in SAMS’ facilities between March 2017 and June 2020; we compared data by facility type, infectious versus non-infectious aetiologies and age.Results Data were available for 5 058 864 consultations, of which 1 228 722 (24%) were respiratory presentations, across 22 hospitals, 22 primary healthcare centres, 3 mobile clinics and 1 polyclinic. The median number of respiratory consultations per month was 30 279 (IQR: 25 792–33 732). Key findings include: 73% of respiratory consultations were for children; respiratory presentations accounted for up to 38% of consultations each month, seasonal variation was evident; respiratory tract infections accounted for 91% of all respiratory presentations. A steep decrease in consultations occurred between the end of 2019 (160 000) and the first quarter of 2020 (90 000), correlating with an escalation of violence in Idlib governorate.Conclusion This study presents the largest quantitative analysis of respiratory data collected during the Syrian conflict. It supports the need for improved measures to aid the prevention, diagnosis and management of respiratory conditions during conflict as well as further research to explore the impact of conflict on respiratory health

Osteoporosis knowledge and awareness among university students in Saudi Arabia

Awareness and knowledge about any disease is the first step to prevent and treat it, so this study evaluates osteoporosis awareness and knowledge in university students. Our results showed a high awareness and good knowledge of osteoporosis. Females were better informed than males. Knowledge increased with increasing education level. PURPOSE: Osteoporosis is a worldwide health problem, including Saudi Arabia where vitamin D deficiency is common. Prevention of osteoporosis must begin by increasing awareness of the disease from a young age. This study aimed to assess awareness and knowledge of osteoporosis among young adults (18-30 years) attending Saudi universities, exploring the relationship between education and gender and the sources of information in this age group. METHODS: A cross-sectional survey was conducted in 337 students (176 females; 161 males) randomly selected from four Saudi universities during January-December 2017. Education level ranged from preparatory year to undergraduate and postgraduate levels. A self-reported questionnaire was designed to assess awareness and knowledge of osteoporosis across several domains, including risk factors for the disease, prevalence, symptoms, prevention, and treatment. RESULTS: Overall, 92% of students had some awareness of osteoporosis through a variety of sources, predominantly via friends. Just over half of all students had a good or high knowledge level overall (53.4 ± 16.6%). Knowledge score correlated with education (r2 = 0.28) and gender (r2 = 0.27); p < 0.0001. Females were better informed than males (57.7 ± 15.4% vs 48.8 ± 16.8%; p < 0.0001). Knowledge increased with increasing education level (preparatory year (47.8 ± 15.3%), undergraduate (53.5 ± 16.5%), and postgraduate (61.8 ± 15.8%); all p < 0.0001). CONCLUSION: Knowledge of osteoporosis was good among university students in Saudi Arabia, higher in females and with increasing years of education. Overall, students were more knowledgeable about risk factors compared to other aspects such as symptoms, prevention, or treatment of osteoporosis