Ahmed H.E. Hassan

Synthesis of the Tricyclic Ring Structure of Daphnanes via Intramolecular [4 + 3] Cycloaddition/SmI2-Pinacol Coupling

A synthetic approach toward the tricyclic 5,7,6-membered ring structure of daphnane-family natural products is described. An intramolecular [4 + 3] cycloaddition reaction of furan with an oxypentadienyl cation constructed the oxa-bridged bicyclic structure in a stereoselective fashion. Structural analysis revealed that the desired exo isomer was predominantly acquired through epimerization. Finally, formation of the five-membered ring was achieved through SmI2-mediated pinacol coupling.

A proposed reactive power controller for DG grid connected systems

Most of currently grid connected Decentralized Generation (DG) systems are power electronics interfaced, and only manage their active power production. With industrial inductive loads, the utility grid has not only to supply their reactive power needs, but also to supply extra reactive power to compensate for the expected power factor deterioration caused by DG active power injection. Among various DG options, Fuel cell technology makes a clean, highly controllable and economically viable DG option. Local reactive power compensation is a particular feature of fuel cell systems, as they will always be very close to the point of usage of electricity. With smart control algorithm of the grid coupling inverter, it is possible to enable reactive power management of the fuel cell DG system. This paper presents a smart control algorithm of the fuel cell DG grid coupling inverter, which provides active/reactive power management capability for the DG unit. The controller modeling and performance validation is performed at a test system, for a proposed operation scenario using Matlab/Simulink and Simpower system blocks. This validation proves the capability of using the proposed controller for power factor improvement.

A proposed dynamic model of Photovoltaic-DG system

Dynamic modeling is important to predict the energy production of Photovoltaic (PV) systems. It is needed to make informed technical and economical decisions. The simulation models of PV systems in literature are good enough for steady state analysis, but they are not suitable for dynamic analysis of grid operating and control conditions. This paper proposes a dynamic PV model suitable for Decentralized Generation (DG) applications. The proposed model relates the electrical output of the PV system to various input environmental parameters. The model is developed in Matlab-Simulink environment, and it is validated comparing the developed PV performance characteristic curves with those of the manufacturers data sheet and those developed by a commercial software package for a Solarex-MSX 60W PV type.

Discovery of 1-(3-(benzyloxy)pyridin-2-yl)-3-(2-(piperazin-1-yl)ethyl)urea: A new modulator for amyloid beta-induced mitochondrial dysfunction

Herein, we report a new series of aliphatic substituted pyridyl-urea small molecules synthesized as potential modulators for amyloid beta (Aβ) induced mitochondrial dysfunction. Their blocking activities against Aβ-induced mitochondrial permeability transition pore (mPTP) opening were evaluated by JC-1 assay which measures the change of mitochondrial membrane potential (ΔΨm). The inhibitory activity of sixteen compounds against Aβ-induced mPTP opening was superior or almost similar to that of the standard Cyclosporin A (CsA). Among them, 1-(3-(benzyloxy)pyridin-2-yl)-3-(2-(piperazin-1-yl)ethyl)urea (5x) effectively maintained mitochondrial function and cell viabilities on ATP assay, MTT assay, and ROS assay. Using CDocker algorithm, a molecular docking model presented a plausible binding mode for 5x with cyclophilin D (CypD) receptor as a major component of mPTP. Moreover, hERG and BBB-PAMPA assays presented safe cardiotoxicity and high CNS bioavailability profiles for 5x. Taken as a whole, this report presents compound 5x as a new nonpeptidyl mPTP blocker may hold a promise for further development of Alzheimers disease (AD) therapeutics.

A proposed framework for dynamic modelling of photovoltaic systems for DG applications

Dynamic modelling and simulation is essential to predict the overall electrical performance of photovoltaic (PV) systems. PV simulation models in the literature are not suitable for dynamic analysis with decentralised generation (DG) applications. This article proposes a framework for PV system dynamic modelling and simulation process. This framework presents the steps required to model the process of solar power generation, reflecting the environmental variables affecting the generation process. Based on the framework steps, a computer simulation model is developed in MATLAB-Simulink of the PV generator, and validated by comparing the developed PV electrical performance characteristic curves with those of the manufacturers data sheet and the ones developed by commercial software. The last step of the proposed framework is dedicated for testing the developed PV model for grid-connected operation. The proposed framework resulted in a simulation photovoltaic decentralised generation model which constitutes a computer-aided design tool that is helpful for real-world solar energy engineering.

Design, synthesis, biological evaluation and molecular modelling of 2-(2-aryloxyphenyl)-1,4-dihydroisoquinolin-3(2H)-ones: A novel class of TSPO ligands modulating amyloid-β-induced mPTP opening

Abstract Translocator protein (TSPO) is involved in modulating mitochondrial permeability transition pore (mPTP) opening/closure leading to either apoptotic cell death via opening of mPTP or cell protection mediated by mPTP blocking and hence intercepting mPTP induced apoptosis. Herein, 2‐(2‐aryloxyphenyl)‐1,4‐dihydroisoquinolin‐3(2H)‐one derivatives have been designed and synthesized as new modulators for amyloid‐&bgr;‐induced mPTP opening. Among all, compound 7c remarkably enhanced mPTP opening while compound 7e showed the highest mPTP blocking activity. Molecular modelling study revealed different binding modes which might underlie the observed opposing biological activities. Both compounds bound to the translocator protein 18 kDa (TSPO) in low micromolar range and elicited good profiles on CYP2D6 and CYP1A2. Taken as a whole, this report presents compound 7e as a hit TSPO ligand for treatment of neurodegenerative diseases and compound 7c as a hit TSPO ligand for promoting cell death of cells over‐expressing TSPO. Graphical abstract Figure. No Caption available.

Synthesis and evaluation of 2-(3-arylureido)pyridines and 2-(3-arylureido)pyrazines as potential modulators of Aβ-induced mitochondrial dysfunction in Alzheimer's disease

A series of 2-(3-arylureido)pyridines and 2-(3-benzylureido)pyridines were synthesized and evaluated as potential modulators for amyloid beta (Aβ)-induced mitochondrial dysfunction in Alzheimers disease (AD). The blocking activities of forty one small molecules against Aβ-induced mitochondrial permeability transition pore (mPTP) opening were evaluated by JC-1 assay which measures the change of mitochondrial membrane potential (ΔΨm). The inhibitory activity of twenty five compounds against Aβ-induced mPTP opening was superior to that of the standard cyclosporin A (CsA). Six hit compounds have been identified as likely safe in regards to mitochondrial and cellular safety and subjected to assessment for their protective effect against Aβ-induced deterioration of ATP production and cytotoxicity. Among them, compound 7fb has been identified as a lead compound protecting neuronal cells against 67% of neurocytotoxicity and 43% of suppression of mitochondrial ATP production induced by 5 μM concentrations of Aβ. Using CDocker algorithm, a molecular docking model presented a plausible binding mode for these compounds with cyclophilin D (CypD) receptor as a major component of mPTP. Hence, this report presents compound 7fb as a new nonpeptidyl mPTP blocker which would be promising for further development of Alzheimers disease (AD) therapeutics.

Synthesis and evaluation of new pyridyl/pyrazinyl thiourea derivatives: Neuroprotection against amyloid-β-induced toxicity

Herein, we report synthesis and evaluation of new twenty six small molecules against β amyloid (Aβ)-induced opening of mitochondrial permeability transition pore (mPTP) using JC-1 assay which measures the change of mitochondrial membrane potential (ΔΨm). The neuroprotective effect of seventeen compounds against Aβ-induced mPTP opening was superior to that of the standard Cyclosporin A (CsA). Fifteen derivatives eliciting increased green to red fluorescence percentage less than 40.0% were evaluated for their impact on ATP production, cell viability and neuroprotection against Aβ-induced neuronal cell death. Among evaluated compounds, derivatives 9w, 9r and 9k had safe profile regarding ATP production and cell viability. In addition, they exhibited significant neuroprotection (69.3, 51.8 and 48.2% respectively). Molecular modeling study using CDocker algorithm predicted plausible binding modes explaining the elicited mPTP blocking activity. Hence, this study suggests compounds 9w, 9r and 9k as leads for further development of novel therapy to Alzheimers disease.

Modeling and optimization of a hybrid power system supplying RO water desalination plant considering CO2 emissions

AbstractSeawater desalination is an attractive choice especially for remote areas where freshwater is rare. Egypt is moving toward the desalination of water as an alternative solution to the decrease in freshwater. The main objective of this study was to design an optimal, economic, and efficient hybrid system that feeds the electric needs of a small-scale brackish reverse osmosis desalination unit and a tourism motel located in Hurghada, Egypt. The optimization problem of sizing different components of hybrid system is a complicated one; it needs a special tool capable of solving it rapidly and effectively. Three different hybrid system scenarios are discussed to select the most optimum combination of them. These scenarios are the following: wind/PV/battery, wind/PV/diesel, and wind/PV/battery/diesel. In this study, a modified particle swarm optimization technique is applied for optimum sizing of the proposed hybrid system scenarios. The optimization problem is solved to minimize the annual total investm...

Construction of 8-Azabicyclo[3.2.1]octanes via Sequential DDQ-Mediated Oxidative Mannich Reactions of N-Aryl Pyrrolidines

A concise synthesis of 8-azabicyclo[3.2.1]octanes via sequential oxidative Mannich reactions is described. This approach involves an intermolecular oxidative Mannich coupling reaction between N-aryl pyrrolidines with TMS enol ether and a subsequent intramolecular oxidative Mannich cyclization of the corresponding silyl enol ether. DDQ is used as a key oxidant for both reactions.