Unveiling the lockdown effects: exploring behavior, dietary habits and weight changes in rural Egypt during COVID-19 lockdown: a cross-sectional retrospective study.

BACKGROUND: The COVID-19 lockdown significantly impacted dietary habits and body weights globally, particularly in Egypt, where 57.03% of the population resides in rural areas, despite lack of information. The study examines the impact of COVID-19 lockdown on the weight changes of the rural Egyptian population through behavioral, physical, and dietary changes. METHODS: A cross-sectional online survey using Microsoft Forms was distributed in Delta regions in Egypt. The questionnaire used a modified version of the validated 14- items PREDIMED MedDiet Adherence Screener (MEDAS). The first part of the questionnaire addressed sociodemographic variables whereas the second one included questions related to dietary, behavioral and weight changes of participants. These changes were statistically tested for significance in relation to BMI, gender, home living, current job and family history of obesity. RESULTS: A total of 306 participated in the study (70% females, 13% obese, 95% living with family, 56% university students, and 36% with family history of obesity). Obese showed a significant increase in sweet intake whereas underweight and normal weight people displayed a significant decrease in eating desire. Both females and males showed significant increase in consumption of fruits and vegetables with significant decrease in soft drink. However, women showed a significant decrease in sport activity relative to men. Participants living with family showed an increase in sweet intake while those living alone explored an increase in meal frequency. Employers revealed a significant decrease in sport activities and people with family history of obesity reported more sleeping times than those without family history of obesity. CONCLUSION: During Covid-19 quarantine, Egyptians' eating habits improved, but daily routines were disrupted. Raising awareness about obesity and providing guidance on maintaining activity, energy, and mood is crucial for future quarantine situations.

The impact of metformin use on the outcomes of relapse-remitting multiple sclerosis patients receiving interferon beta 1a: an exploratory prospective phase II open-label randomized controlled trial.

BACKGROUND: Multiple sclerosis (MS) is a chronic demyelinating neurodegenerative disorder. Elevated levels of pro-inflammatory mediators and some oxidative stress parameters can accelerate the demyelination process. We aimed to investigate the efficacy and safety of metformin as an adjuvant therapy to interferon beta 1a (IFNß-1a) in relapsing-remitting multiple sclerosis (RRMS) patients. METHOD: Eighty RRMS patients were equally divided into 2 groups: the intervention group receiving IFNß-1a plus 2 gm of metformin once daily and the control group receiving IFNß-1a alone. Interleukin 17 (IL17), interleukin 22 (IL22), malondialdehyde (MDA), T2 lesions in magnetic resonance imaging (MRI) and expanded disability status scale (EDSS) were assessed at the baseline and then after 6 months. RESULTS: At baseline, there were no statistically significant differences between the two groups (p > 0.05). After 6 months, the change in the median (interquartile range) of the results for both the intervention and control group were; IL17 (- 1.39 (4.19) vs - 0.93 (5.48), p = 0.48), IL22 (- 0.14 (0.48) vs - 0.09 (0.6), p = 0.53), and EDSS (0 vs 0, p = 1), respectively. The mean (standard deviation) change in MDA for the intervention and control group was - 0.93 (2.2) vs - 0.5 (2.53), p = 0.038, respectively. For MRI results, 21 patients had stationary and regressive course and 1 patient had a progressive course in the intervention arm vs 12 patients had stationary and regressive course and 4 had a progressive course in the control arm, p = 0.14. CONCLUSION: Adding metformin to IFNß-1a demonstrated a potential effect on an oxidative stress marker (MDA). However, there is no statistically significant effect on immunological, MRI and clinical outcomes. We recommend larger scale studies to confirm or negate these findings. TRIAL REGISTRATION: ClinicalTrials.gov number: NCT05298670, 28/3/2022.

Influence of high porous sponges for improving the interfacial evaporation from hemispherical solar distillers.

The present study aims to improve the palatable water production from the hemispherical cover solar distiller (HSD). To augment the palatable water produced from the hemispherical cover, a black sponge was utilized as a porous medium using different thicknesses, which augments the interfacial evaporation through the capillary effect of the water through the sponge. The rate of condensation of the hemispherical cover depends on the higher interaction of air from the ambient through wind velocity as the exposure area of the hemispherical cover is relatively higher as compared to the other traditional distillers. The rate of evaporation from the distillers depends on the interfacial materials used in the distillation unit, and this is achieved by using a highly porous black sponge to attain a higher evaporation rate. The thickness of the black porous sponge was optimized (1 to 4 cm), which was the operating parameter for better interfacial evaporation through the sponge, and the same has been compared to the conventional HSD without a porous sponge medium. Results showed a significant improvement in the evaporation rate using a porous medium as the palatable water produced from the HSD was improved by 72.29% using 3 cm as sponge thickness inside compared to the conventional HSD without the porous medium. The cumulative palatable water produced from the HSD using 3 cm as sponge thickness was found as 7150 mL/m2, whereas the conventional HSD without sponge, it was found as 4150 mL/m2. Moreover, using a porous sponge layer as an interfacial evaporation medium, the exergy and energy efficiencies were improved by about 512.87 and 70.53%, respectively. Similarly, with the influence of a porous sponge as an interfacial evaporation medium, the distilled water cost decreased by 41.67% more than the conventional HSD.

What's your cup of tea? The role of herbal compounds in the management of multiple sclerosis.

Multiple Sclerosis (MS) is a chronic, inflammatory, neurodegenerative disease that is characterized by a complex etiology. Efforts towards the management of MS have long been directed towards symptomatic relief, as well as the use of immune-modulatory, disease modifying therapies; however, inconsistent treatment responses still prevail, increasing the risk for disease progression. While a great deal of research attempted to unravel the complexity of treatment responses in light of epigenetic variability, parallel efforts in the direction of alternative medicine may be as paramount. Herbal compounds have long been regarded as safe and versatile options for aiding in various disorders, including neurodegenerative conditions like MS. Numerous studies have taken interest in a myriad of herbal plants for their potential benefit in alleviating some of the most common MS symptoms such as spasticity and fatigue, delaying the progression of the disease, as well as influencing the overall quality of life for MS patients. This review aims to provide a comprehensive overview of recent clinical studies examining the effects of various herbal plants on different aspects of MS, in an attempt to shed light on an important tool for aiding in the management of this complex and multifactorial disease.

Prevalence of Drug-Drug Interactions in Primary Care Prescriptions in Egypt: A Cross-Sectional Retrospective Study.

In clinical practice, drug-drug interactions (DDIs) pose significant risks to a large number of patients. Consequently, healthcare providers are required to diligently identify, monitor, and effectively handle these interactions in order to enhance patient outcomes. In Egypt, DDIs are poorly addressed, with no reports for DDIs in primary care. In our cross-sectional, retrospective, observational study, we collected a total of five thousand, eight hundred and twenty prescriptions across eight major governorates in Egypt. Prescriptions were collected over a span of 15 months between 1 June 2021 and 30 September 2022. These prescriptions were analyzed for potential DDIs using the Lexicomp® drug interactions tool. The prevalence of DDIs was found to be 18%, with 22% of the prescriptions having two or more potential DDIs. Moreover, we found 1447 DDIs of categories C (monitoring therapy recommended), D (therapy modification suggested), and X (avoid combination). The most commonly interacting drugs in our study were diclofenac, aspirin, and clopidogrel, while non-steroidal anti-inflammatory drugs (NSAIDs) were the most reported therapeutic class implicated in pharmacologic DDIs. Pharmacodynamic agonistic activity was the most common mechanism of interaction. Therefore, it is crucial to conduct screenings, detect early signs, and closely monitor drug-drug interactions (DDIs) to enhance patients' overall health outcomes, medication responses, and safety. In this regard, the clinical pharmacist assumes a vital role in implementing these preventive measures.

Adsorption air conditioning: a comprehensive review in desiccant materials, system progress, and recent studies on different configurations of hybrid solid desiccant air conditioning systems.

The desiccant air conditioning system has multiple advantages (e.g., no use of ozone-depleting refrigerants, highly efficient moisture control, easy regenerative integration) over traditional vapor-compression refrigeration systems, thus increasingly attracting more research interest. Recently, several studies have been conducted that primarily aimed to enhance the overall performance of desiccant air conditioners by innovating new desiccant materials, innovating new system configurations and improving system designs and controls, and integrating different hybrid energy sub-systems technologies. Therefore, this paper provides a comprehensive review of the studies mentioned earlier. The present comprehensive review dealt with several axes: first, an overview of the importance of using desiccant air conditioners and their operations, and performance indicators. Second, a summary statement for desiccant materials that includes: the new innovative desiccant materials and the most important composite desiccant materials. Third, detailed information on the newest innovative designs and configurations of desiccant air conditioning systems and their control systems. Fourth, a detailed statement on the most important hybrid energy sub-systems technologies integrated with desiccant air conditioners. Based on the latest developments in desiccant air conditioning systems, this study presents discussions of urgent issues and recommendations for future work that can help focus necessary efforts to find solutions to critical and pending problems, which lead to further improvements in the overall performance of desiccant air conditioners.

Hemispherical solar distiller with truncated circular cone-shaped reflector mirrors (TCC-RM): optimum inclination of reflector mirrors.

The present study aims to achieve the highest cumulative yield of the hemispherical distillers, by designing and constructing new reflector mirrors, which are truncated circular cone-shaped reflector mirrors (TCC-RM). To obtain the optimum inclination of TCC-RM that achieves the highest hemispherical distiller's performance, eight inclination angles (10°, 15°, 20°, 25°, 30°, 35°, 40°, and 45° with vertical) were experimentally studied. To achieve this, a series of experimental tests were carried out on the three hemispherical solar distillers: the first represents the reference distiller (traditional hemispherical solar distiller (THSD)) and the other two devices are the hemispherical solar distiller with truncated circular cone-shaped reflector mirrors (HSD-TCCRM) with different inclination angles. The experimental results indicate that utilizing TCC-RM with a 25° inclination angle achieves the maximum cumulative yield of 8.35 L/m2 with an improvement of 42.74% compared to THSD. While the utilization of TCC-RM with the inclination angles of 30°, 35°, 20°, 40°, and 15° achieves the cumulative yield of 7.9, 7.3, 7.05, 6.67, and 6.6 L/m2 compared with 5.85 L/m2 for THSD. On the contrary, adjusting the inclination angle of TCC-RM at 10° and 45° affects negatively the cumulative yield of the HSD with TCC-RM in comparison with THSD. Based on the data of cumulative yield, daily efficiency, and the economic analysis it is recommended to utilize TCC-RM with a 25° inclination angle to achieve the highest performance and minimum distillate cost of hemispherical solar distillers.

Hemispherical Solar Distiller Performance Utilizing Hybrid Storage Media, Paraffin Wax with Nanoparticles: An Experimental Study.

The traditional method of obtaining fresh water for drinking is by burning fossil fuels, emitting greenhouse gases into the atmosphere. However, renewable energy is gaining more traction since it is available free of cost for producing fresh water. In this study, Al2O3 nanoparticles were distributed in a phase change material (paraffin wax) that had been fixed at a hemispherical distiller water basin. Three scenarios with three hemispherical distillers were examined. A conventional hemispherical distiller (CHD), a conventional hemispherical distiller with paraffin wax as a phase change material (CHD-PCM), and a conventional hemispherical distiller with PCM partially filled with Al2O3 nanoparticles (CHD-N-PCM) were tested under the same climatic conditions. The experimental results showed that CHD gave a daily yield of 4.85 L/m2/day, while CHD-PCM increased the yield to up to 6.2 L/m2/day with a 27.84% daily yield enhancement. The addition of Al2O3 nanoparticles to paraffin wax CHD-N-PCM improved hemispherical distillate yield up to 8.3 L/m2/day with a 71.13% increase over CHD yield.

Experimental investigation on a modified design of hemispherical solar distiller with v-corrugated iron trays and wick materials for improving freshwater production.

The low energy efficiency of the solar distillers is one of the key barriers to their effectual usage in the desalination domain. Hence, this work introduces an experimental investigation to enhance the freshwater productivity of the hemispherical solar distiller with different trays' configurations and utilizing wick materials. This was achieved by utilizing iron trays and wicks in the circular basin of hemispherical solar still in order to increase the vaporization surface area for better heat transfer of saline water. The performance of the hemispherical solar distiller was investigated with flat and v-corrugated iron trays configurations. Three distillers were designed and examined, namely, conventional hemispherical solar distiller, hemispherical solar distillery with flat iron trays, and hemispherical solar distiller with v-corrugated iron trays. Moreover, the combined effects of using wick materials with flat and v-corrugated iron trays in the basin of hemispherical distiller have been also investigated. Experiments were carried out at the desert climate conditions of El-Oued (33°27'N, 7°11'E), Algeria. The results showed that the productivity improvement is 42.85% and 14.30% over the conventional hemispherical distiller for v-corrugated and flat trays hemispherical solar still (HSD), respectively. While the inclusion of wick materials with v-corrugated iron trays further increases the productivity by about 83.12% over the reference distiller. Moreover, the energy efficiency of the flat trays HSD, v-corrugated trays HSD, HSD flat trays and wicks, and HSD v-corrugated trays and wicks is 38.72%, 48.28%, 52.16%, and 61.67%, respectively. Additionally, the .cost of freshwater production of HSD v-corrugated trays and wicks was 41.72% lower than that of a traditional hemispherical distiller.

Recent technological advancements in membrane distillation and solar stills: preheating techniques, heat storage materials, and nanomaterials - a detailed review.

Freshwater and energy are critical components for the growth and progress of societies. The scarcity of freshwater and rapid population growth, especially in remote countries, has led to an urgent need to develop desalination technologies in order to raise its productivity and reduce its energy consumption rates. Membrane distillation is one of the effective methods characterized by its high productivity, but its disadvantage by higher electricity consumption. Also, solar stills are one of the sustainable and economical technologies, but the disadvantage by lower productivity. Accordingly, this manuscript dealt with a comprehensive review and detailed comparison of the most important modifications and innovations that were made to the design of the membrane distillation units, which aim to reduce electricity consumption rates, as well as the design of solar stills, which aims to maximize the productivity and efficiency. This was done by providing a detailed comparison of the most important three axes of modifications and innovations that were addressed by recent previous studies on the design of membrane distillation units and solar stills, and their statement as follows: preheating technology, use of the thermal storage materials, and nanomaterials technology. Finally, based on this review, the authors make some recommendations for future work in the field of solar and membrane desalination.

Optimization of the hemispherical solar distiller performance assisted by high thermal conductivity metal trays incorporated with reflective mirrors.

The present comprehensive study aims to achieve the highest freshwater productivity of hemispherical solar distillers which are characterized by having a large condensing and receiving surface area. This was done by incorporating two effective modifications to the design of the hemispherical solar distiller, namely the use of metal trays with high thermal conductivity and reflective mirrors. In the present experimental work, three different high thermal conductivity metal trays (steel, zinc, and copper) incorporated with the reflective mirrors were tested under the same climate conditions, in order to determine the optimum selection of metal trays that are incorporated with the reflective mirrors that achieve the highest performance of the hemispherical distillers. To realize this objective, four distillers were fabricated and tested at the same climate condition namely: Hemispherical solar Distiller with Black Silicone Walls (HSD-BSW) which represent the reference case, Hemispherical Solar Distiller with Steel Trays and Reflective Mirrors (HSD-ST&RM), Hemispherical Solar Distiller with Zinc Trays and Reflective Mirrors (HSD-ZT&RM), and Hemispherical Solar Distiller with Copper Trays and Reflective Mirrors (HSD-CT&RM). The experimental results presented that the utilization of copper trays incorporated with reflective mirrors (HSD-CT&RM) represents the very effective option to achieve the highest performance of the hemispherical solar distillers. The cumulative production achieve by the reference HSD-BSW reached 4.65 l/m2day, while utilization of copper trays incorporated with reflective mirrors (HSD-CT&RM) increases the cumulative production to 9.5 l/m2day, with an improvement of 104.3%. Also, utilization of copper trays incorporated with reflective mirrors (HSD-CT&RM) improves the daily thermal and exergy efficiencies by 102.4% and 194.9%, respectively compared to HSD-BSW. Additionally, the economic feasibility showed that the use of copper trays incorporated with reflective mirrors (HSD-CT&RM) is a very effective option as it reduces the cost of distilled water by 44.1%.

Enhancing the hemispherical solar distiller performance using internal reflectors and El Oued sand grains as energy storage mediums.

This paper presents a comprehensive experimental study of the some effective modifications which aim to improve the cumulative productivity of solar distillers, in order to reach the best modification that achieves the highest cumulative productivity of hemispherical distillates. The experimentations were carried on the hemispherical distillers which are characterized by a large area of receiving and condensation. To obtain the best modification that achieves the highest cumulative productivity, the present comprehensive studies were conducted on two experimental scenarios. In the first scenario, the influences of internal reflective (Reflective Mirrors and Reflective Aluminum Foil) on hemispherical distillers performance was studied. In the second scenario, the influences of internal reflective with El-Oued sand grains as the energy store mediums on hemispherical distiller performances was studied. To achieve this goal, we designed and fabricated three hemispherical distillers, the first distiller represents the reference case (Conventional Hemispherical Solar Still-CHSS), the second is the Hemispherical Solar Still with Internal Reflective Mirrors (HSS-IRM), and a third is the Hemispherical Solar Still with Internal Reflective Aluminum Foil (HSS-IRAF). In the second experimental scenario, the El-Oued sand grains were added to the basin of the second and third distillers as follows; where the second distiller became a Hemispherical Solar Still with Internal Reflective Mirrors and El-Oued sand grains (HSS-IRM & SG), and a third distiller became a Hemispherical Solar Still with Internal Reflective Aluminum Foil and El-Oued sand grains (HSS-IRAF & SG). The results presented that the cumulative production of reference distiller (CHSS) up to 4750 mL/m2, while use of internal reflective mirrors and El-Oued sand grains (HSS-IRM & SG) increases the production to 9400 mL/m2 day. The maximum improvement in cumulative distillate production, exergy efficiency, and thermal efficiency was recorded for utilization of internal reflective mirrors and El-Oued sand grains (HSS-IRM & SG) which reached 98, 200.9, and 96%, respectively, compared to reference case (CHSS). The economic feasibility indicated that the utilization of HSS-IRM & SG represent the good modification which reduced the cost of freshwater productivity by 49.1% compared to CHSS.

Augmenting the productivity of stepped distiller by corrugated and curved liners, CuO/paraffin wax, wick, and vapor suctioning.

This paper aimed to improve the thermal performance of the stepped solar still. So, the effects of using different types of basin liners (corrugated and curved basin liners), jute cloth wick, CuO/paraffin wax, and vapor suction on the stepped solar still performance were investigated. The CuO/paraffin wax was placed into a groove parallel to the basin steps' liner. Also, the stepped distiller was integrated with an external condensation unit. The experimental results revealed that using the corrugated and curved liners increased the productivity of the modified stepped solar still (MSSS) by 42% and 33%, respectively. In addition, using the corrugated liner with wick, corrugated liner with wick and CuO/paraffin wax, corrugated liner with wick, CuO/paraffin wax, and vapor suction improved the freshwater productivity of the distiller by 95%, 127%, and 170%, respectively. At the last studied case (MSSS with corrugated liner, wick, CuO/paraffin wax, and vapor suction), the daily freshwater productivities of the MSSS and conventional still (CSS) were 7000 and 2600 mL/m2·day, respectively. Also, the thermal efficiency of MSSS was calculated as 59% which was obtained at the last studied case. And the efficiency of the CSS was 35%. Besides, the distilled water cost of CSS and MSSS with corrugated liner with wick, CuO/paraffin wax, and vapor suction was 0.023 and 0.014 $/L, respectively.

A comparative study of hemispherical solar stills with various modifications to obtain modified and inexpensive still models.

The present study aims to obtain the best modification of the hemispherical solar distillers that achieves the highest productivity with the lower inexpensive. To achieve this goal, this paper dealt with conducting a comparative study, operating performance analysis and an economic study of two different modifications, and comparing them with the reference distiller in order to obtain the best adjustments that achieve the highest productivity at the lowest cost. In the first modification, CuO nanoparticles with three different concentrations (0.1, 0.2, and 0.3%) were added to the basin water, to increase the intensity of absorbed solar energy, improve the thermal properties of basin fluid, and then increase the rate of vapor generation inside the distillation basin. In the second modification, water film glass cooling technology with three different flow rates (1.5, 2, and 2.5 L/h) was utilized to increase the water vapor condensation rate. In this experimental study, three hemispherical distillers were fabricated and tested under the same climate conditions at a 1-cm basin fluid depth, namely, conventional hemispherical solar still (CHSS), hemispherical solar still with glass cover cooling (HSS-C), and hemispherical solar still with CuO-water-based nanofluid (HSS-N). The experimental results presented that the average daily accumulative yield of CHSS is 3.85 L/m2/day, while the daily accumulative yield of HSS-N increases to 5.75, 6.40, and 6.80 L/m2/day with improvement 49.3, 66.2, and 76.6% at volume fraction 0.1, 0.2, and 0.3%, respectively. Also, the daily accumulative yield of HSS-C increases to 4.9, 5.35, and 5.7 L/m2/day with improvements of 27.3, 39, and 48% at water film flow rates of 1.5, 2, and 2.5 L/h, respectively. The cost of distilled water produced from CHSS is 0.0106 $/L, while the utilization of HSS-C (2.5 L/h) and HSS-N (0.3%) reduces the cost of distilled water to 0.0072 and 0.0066 $/L, respectively. Based on accumulative yield and economic analyzes, it is recommended that the modified HSS-N (0.3% volume fraction) be utilized to achieve the highest accumulative yield and the lowest price of the produced distilled water.

Experimental investigation on the performance improvement of tubular solar still using floating black sponge layer.

The experimental study in this manuscript aims to enhance the performance of tubular solar distillers. The tubular distillers are characterized by having a large surface area for receiving and condensing compared to a single-slope distiller, and accordingly, the use of floating sponge layers is a good and very effective choice in increasing the rate of evaporation and thus improving the cumulative yield of the tubular distillers. In order to obtain the optimum specifications of the sponge layers that achieve the highest performance of the tubular distillers, four tubular distillers were designed and constructed; the first is a reference distiller without sponge and the other three tubular distillers contain the sponge layers with different specifications. The experimentations were conducted in two stages: in the first stage, three different thicknesses of the sponge layer (20, 30, and 40 mm) were studied. In the second stage, three different densities of the sponge layer (16, 20, and 30 kg/m3) were studied. All test cases were compared with reference distiller under the same climatic conditions of Egypt. The results show that the utilization of a floating sponge improves the tubular distiller performance. The peak improvement in the accumulative yield of tubular distillers was achieved in case of utilizing a sponge layer with a 30-mm thickness and 16-kg/m3 density. The reference distiller gives maximum accumulative yield of 3.72 L/m2 day while the floating sponge layer utilization improves the accumulative yield to 5.92 L/m2 day with 59.2% improvement. Also, the utilization of floating sponge layer reduced the cost of distillate yield by 36.3% compared to reference distiller.

Enhancement of the performance of hemispherical distiller via phosphate pellets as energy storage medium.

In this experimental work, the performance of hemispherical distiller has been enhanced via phosphate pellets. To investigate the best approach to the phosphate pellet utilization in a basin of hemispherical distiller to achieve the highest performance, the present study was carried out in two stages. In the first stage, 250 g of phosphate pellets was arranged in a layer of 5 mm thickness placed at the bottom of the basin. In the second stage, the phosphate pellets were distributed in a homogeneous manner in basin salt water with two concentrations 1% (10 g/L) and 2% (20 g/L) without aggregation on the basin. To achieve this idea, in the first test stage, two distillers were compared, the first is the conventional hemispherical distiller which represents the reference distiller (CHSS) and the second is the modified hemispherical distiller with a phosphate layer (MHSS-PL). In the second test stage, three distillers were compared, the first is the CHSS which represents the reference distiller, the second is the modified hemispherical distiller which contained 1% phosphate (MHSS-1), and the third is the modified hemispherical distiller which contained 2% phosphates (MHSS-2). The experimental results show that the cumulative yield was 4.6, 6.32, 6.15, and 6.85 L/m2·day for CHSS, MHSS-PL, MHSS-1, and MHSS-2, respectively. The results showed that the utilization of the phosphate pellets as a storage medium enhanced the performance of the hemispherical distiller. The enhancement in the distiller productivity was 37.4, 33.7, and 47.9% for MHSS-PL, MHSS-1, and MHSS-2, respectively, compared to conventional hemispherical solar still (CHSS). The peak enhancement in the productivity was achieved in the case of modified hemispherical solar still with 2% (20 g/L) phosphate pellets (MHSS-2).

A comprehensive review of technologies used to improve the performance of PV systems in a view of cooling mediums, reflectors design, spectrum splitting, and economic analysis.

Solar photovoltaic panels are increasingly being used throughout the world, particularly in Egypt, where a station has been constructed in the city of Aswan with a capacity of 1480 MW, and is classified as one of the largest photovoltaic plants in the Middle East country, where photovoltaic systems are characterized as environmentally friendly and do not produce any pollutants, and photovoltaic systems have the ability to operate with diffuse radiation. It is therefore very important to understand how photovoltaic panels respond to changing weather conditions and how climate conditions affect the performance of photovoltaic cells, as only 15-20% of solar radiation can be converted to electricity, while the rest is wasted as thermal heat. There are two very important factors influencing the efficiency of the photovoltaic cells: the cell temperature and the solar radiation intensity on the photovoltaic cells. Cooling of the optical surfaces is one of the main factors that must be considered in order to achieve the highest efficiency when operating the solar PV systems. By using the appropriate cooling technology for the photovoltaic cells, the electrical efficiency is improved, and the cell degradation rate is decreased over time, which increases the life span of the PV panels. In some applications, such as industrial and domestic applications, excess energy removed with cooling technology could be used. The cooling mediums used to cool the PV panels are water, air, PCM, and nanofluid. Also, the spectral splitting utilization represents a good solution for hybrid solar photovoltaic-thermal applications to obtain higher performance of the photovoltaic. This paper gives a brief analysis of technologies used to improve PV systems efficiency in terms of the nature of cooling media, spectral splitting, and reflectors. Moreover, the economic study of these techniques is presented to demonstrate their economic feasibility. The aims of the present review paper are to provide good knowledge and understanding of all technologies used to improve the performance of PV systems and demonstrate the economic feasibility of these technologies.

Performance improvement of modified tubular solar still by employing vertical and inclined pin fins and external condenser: an experimental study.

The current experimental work aims to improve an accumulative yield of tubular solar distillers. This was achieved by utilizing the pin fins and external condenser coupled with the tubular solar distiller. The tubular distillers are characterized by having a large receiving and condensing surface area compared to a traditional single-slope distiller; therefore, the utilization of pin fins is very effective to increase the evaporation rate, as well as the external condenser was utilized to increase the condensation rate. In order to achieve this vision, the experimental study mainly included two axes: namely, in the first axis, the effect of utilizing the pin fins on the cumulative yield of tubular solar distillers was studied, as well as obtaining the optimal orientation of the pin fins to reduce the shadow effect generated inside the basin. In the second axis, the effect of utilizing an external condenser and the inclined pin fins on an accumulative yield of the tubular solar distiller was studied. To investigate this idea, in the first study axis, three tubular distillers were constructed and tested at the same conditions, namely conventional tubular solar still (CTSS), modified tubular solar still with vertical pin fins (MTSS-VPF), and modified tubular solar still with inclined pin fins (MTSS-IPF). In the second study axis, two tubular distillers were constructed and tested at the same conditions, namely CTSS and modified tubular solar still with inclined pin fins and condenser (MTSS-IPF+Condenser). The results presented that the enhancement in accumulative yield reached 18% and 27.6% for utilizing the vertical and inclined pin fins, respectively, as compared to CTSS. These results show that the utilization of inclined pin fins represents a good option to improve the accumulative yield of tubular distillers. Also, the accumulative yield and the daily efficiency achieved by utilization of the external condenser and the inclined pin fins (MHSS-IPF+Condenser) reached to 5.94 L/m2/day and 54.9% with an improvement of 70.2% and 71.6%, respectively, as compared to CTSS.