A novel stand-alone solar-powered agriculture greenhouse-desalination system; increasing sustainability and efficiency of greenhouses

This is the author accepted manuscript.The countries in the Middle East and North Africa (MENA) region are suffering from the scarcity of freshwater resources. With the economic development and population growth, planning the additional water supplies is critical for this region. Desalination of saline water is, therefore, considered as a strategic alternative water resources and technology to be adopted in MENA region. On the other hand, open field agriculture in such conditions is not economical particularly with high ambient temperature and solar intensity. Agriculture Greenhouses (GH) present a suitable alternative for different plants growth for the region’s desert. In most cases GHs can reduce about 90% of irrigating water demand compared open field. With the available high solar energy, integration of solar – GH – desalination presents a real challenge and is the field of newly funded N-M R&D proposal. This paper presents an integration of solar energy, agriculture GH and suitable desalination processes targeting the development and pilot testing of a novel stand-alone system that grows its energy and irrigation water demand.British CouncilScience & Technology Development Fund (STDF), Egyp

Analysing the material suitability and concentration ratio of a solar-powered parabolic trough collector (PTC) using Computational Fluid Dynamics

This is the final version. Available on open access from MDPI via the DOI in this recordSolar-powered desalination is a sustainable solution for countries experiencing water scarcity. Several studies have presented different solutions to provide cleaner production in desalination systems. Parabolic trough collector (PTC) is one of these solutions that has proven to be superior among solar concentrators. Furthermore, a number of studies have investigated the use of PTC for distillation of saline water in response to water scarcity. In this study, a modified PTC model was developed, in which the heat exchanger was replaced by a condensation tube to reduce the energy consumption, and a black layer was introduced to the surface of the receiver to enhance its absorptance. As a reference case, the system productivity according to average solar intensities in Zagazig, located at 30°34′N 31°30′E in the North East of Egypt, is estimated. The results indicated that the maximum production rate that can be attained is 1.72 kg/hr. Then, the structure of the system is evaluated with the aid of Computational Fluid Dynamics (CFD) modelling, in order to enhance its productivity. Many materials are examined and the results recognised copper as the most suitable material amongst marine grade metals (i.e., aluminium, galvanised steel and stainless steel) to construct the receiver tube. This is due to its superior thermal performance, satisfactory corrosion resistance, and acceptable cost. Afterwards, the selected receiver tube was employed to identify the optimal Concentration Ratio (CR). Consequently, a CR of 90.56 was determined to be the optimum value for Zagazig and regions with similar solar radiation. As a result, the system’s productivity was enhanced drastically, as it was estimated that a maximum production rate of 6.93 kg/hr can be achieved.Science, Technology, and Innovation Funding. Authority (STIFA) of EgyptBritish Counci

Natural coagulates for wastewater treatment; a review for application and mechanism

The increase of water demand and wastewater generation is among the global concerns in the world. The less effective management of water sources leads to serious consequences, the direct disposal of untreated wastewater is associated with the environmental pollution, elimination of aquatic life and the spread of deadly epidemics. The flocculation process is one of the most important stages in water and wastewater treatment plants, wherein this phase the plankton, colloidal particles, and pollutants are precipitated and removed. Two major types of coagulants are used in the flocculation process included the chemical and natural coagulants. Many studies have been performed to optimize the flocculation process while most of these studies have confirmed the hazardous effects of chemical coagulants utilization on the ecosystem. This chapter reviews a summary of the coagulation/flocculation processes using natural coagulants as well as reviews one of the most effective natural methods of water and wastewater treatment

A Model of Electrically Stimulated Auditory Nerve Fiber Responses with Peripheral and Central Sites of Spike Generation

A computational model of cat auditory nerve fiber (ANF) responses to electrical stimulation is presented. The model assumes that (1) there exist at least two sites of spike generation along the ANF and (2) both an anodic (positive) and a cathodic (negative) charge in isolation can evoke a spike. A single ANF is modeled as a network of two exponential integrateand-fire point-neuron models, referred to as peripheral and central axons of the ANF. The peripheral axon is excited by the cathodic charge, inhibited by the anodic charge, and exhibits longer spike latencies than the central axon; the central axon is excited by the anodic charge, inhibited by the cathodic charge, and exhibits shorter spike latencies than the peripheral axon. The model also includes subthreshold and suprathreshold adaptive feedback loops which continuously modify the membrane potential and can account for effects of facilitation, accommodation, refractoriness, and spike-rate adaptation in ANF. Although the model is parameterized using data for either single or paired pulse stimulation with monophasic rectangular pulses, it correctly predicts effects of various stimulus pulse shapes, stimulation pulse rates, and level on the neural response statistics. The model may serve as a framework to explore the effects of different stimulus parameters on psychophysical performance measured in cochlear implant listeners

ICAR: endoscopic skull‐base surgery

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Prevalence and Predictors of Remission and Sustained Remission in Patients with Rheumatoid Arthritis from the United Arab Emirates: A Two-Year Prospective Study

Jamal Al-Saleh,1 Ahlam Almarzooqi,2 Ahmed A Negm1 1Rheumatology, Dubai Hospital, Dubai Health Authority, Dubai, United Arab Emirates; 2Rheumatology, Al Qassimi Hospital, Emirates Health Services, Sharjah, United Arab EmiratesCorrespondence: Jamal Al-Saleh, Rheumatology, Dubai Hospital, Dubai Health Authority, P.O. 7272, Dubai, United Arab Emirates, Tel +9714-219 5506, Fax +97142195788, Email [email protected]: To estimate the prevalence of remission and sustained remission for more than 12 months in a cohort of patients with rheumatoid arthritis in the United Arab Emirates and explore predictors of remission and sustained remission in these patients.Methods: A two-year prospective study conducted in Dubai Hospital (January 1, 2018-December 31, 2019) included all consecutive patients with rheumatoid arthritis attending the rheumatology clinic. Patients with a Simplified Disease Activity Index ≤ 3.3 and/or Clinical Disease Activity Index ≤ 2.8 in December 2018 were considered in remission and followed until December 2019. Those who maintained remission through 2019 were considered in sustained remission.Results: In this study, a total of 444 patients were followed for a 12-months period. The percentage of remission achieved in RA patients was 30.4% according to the Clinical Disease Activity Index, 31.1% according to Simplified Disease Activity Index, and 50.9% according to the Value of Disease Activity Score 28 (DAS28) remission criteria. The 12-months sustained remission rates ranged from 38.3% for the ACR-EULAR to 69.3% for the DAS28. Male gender, shorter disease duration, better functioning as evaluated by the Health Assessment Questionnaire Disability Index (lower HAQ scores), and higher compliance rates are among sustained remission predictors.Conclusion: Establishing “real-world” data and understanding local predictors to sustained remission is principal for implementing timely and appropriate patient-tailored strategies. These strategies include early detection, close monitoring, and enhancing treatment adherence among UAE patients.Keywords: predictors, remission, rheumatoid arthritis, sustained remission, United Arab Emirate

Impact of inclined double-cutoff walls under hydraulic structures on uplift forces, seepage discharge and exit hydraulic gradient

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record In hydraulic structures design, using cutoff walls is essential to reduce and control the resultant uplift force (U), seepage discharge (Q), and exit hydraulic gradient (i). This research investigates the effectiveness of inclined double cutoff walls under hydraulic structures, considering the influence of depths, locations, and inclination angles of the upstream and downstream cutoff walls by using Finite Element Method (FEM). The results confirmed that installing a deeper cutoff wall on the downstream reduces the exit gradient even further. In the case of the cutoff walls located in the upstream and downstream ends, the exit gradient will be less than when the cutoff walls are installed at a closer distance. Increasing the inclination angle of downstream cutoff wall has a major impact on exit gradient reduction. Embedment of cutoff walls in the upstream and downstream ends with right angles and equal depths reduces the seepage discharge more than other cases

Combined-free flow over weirs and below gates

The results of an experimental investigation on the characteristics of the combined flow over contracted sharp-crested rectangular weirs and below contracted sharp-crested rectangular gates are presented. The experiments are carried out in a laboratory flume using various geometrical dimensions under different flow conditions. The basic principles are employed to correlate the discharge to the relevant geometrical and hydraulic parameters in nondimensional form. The experimental data are then used to develop a general nondimensional equation for predicting the discharge through the combined system knowing its geometry and the head of water over the weir. It was found that only one equation describes both horizontal and sloping channels with either mild or steep slopes. Also, the modular limit for combined flow is discussed and an equation for its calculation is presented as well. The effects of viscosity and surface tension are addressed in terms of Reynolds number and Weber number