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Application of solvent evaporation technique for pure drug crystal spheres preparation

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Particuology 2022年第8期20卷 79-89页

作者： omar Mady Department of Pharmaceutical Technology Faculty of Pharmacy Tanta UniversityEgypt

An innovative application ofthe solventevaporation technique was *** tech nique is a technique for drug encapsulation and nanosphere *** widely used technique is also facing the problem of low actual drug entrapment percent,which is not economic from the industrial *** goal of this work is trying to use the advantage of this technique concerning the product sphericity and the ability to control particle size,to prepare a drug as pure crystals *** is selected as a model *** spheres are formed by using Polyvinyl pyrrolidone(PVP)or Polyethylene glycol(PEG)as an anti-aggregating agent but not formed on using tween or *** size and actual drug content depend on the concentrations the anti-aggregating agent *** of the drug crystal spheres are porous with empty sphere internal structure on using PvP but spongy and rough on using *** drug has its identity chemical form in the drug crystal *** scan of spheres prepared on using PEG showed a characteristic ether *** showed melting endothermic peak of PEG,but X-ray showed minor change in the drug crystal *** release profiles from crystal spheres prepared with the same anti-aggregating agent are close to each *** drug release profiles from drug crystal spheres prepared by using PEG are more controlled than that prepared by using *** drug release mechanism is *** was concluded that,the same technique could be suggested for preparation ofother biomedical material in pure crystals spheres with controlled particle *** properties may encourage to prepare very small particles with spherical shape for inhalation or injection as an innovative particle technology application for the widely used technique.

关键词： Solvent evaporation technique Drug crystal spheres Ibuprofen Polyvinyl pyrrolidone Polyethylene glycol

Monolayer MoS_(2)/n-Si Heterostructure Schottky Solar Cell

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Journal of Renewable Materials 2022年第7期10卷 1979-1988页

作者： omar Salih omar The University of Duhok College of ScienceDepartment of PhysicsDuhokKurdistan RegionIraq

Monolayer MoS_(2)has a promising optoelectronics property,with a bandgap in the visible range;the material is a potential candidate for solar cell *** this work,we grew MoS_(2)monolayers using a low-pressure chemical vapor deposition *** produce uniform wafer-scale MoS_(2)monolayer films,precursors molybdenum dioxide(MoO_(2))and sulfur(S)are *** force microscopy was used to quantify the thickness of the monolayers,and the result was validated by Raman *** electron microscopy(TEM)was used to confirm the crystalline quality of the monolayers,and photoluminescence spectroscopy was used to evaluate their optical *** were able to create a Schottky solar cell with a MoS_(2)monolayer up to 1 cm2 area by transferring monolayer film to n-type *** MoS_(2)/n-Si Schottky solar cell demonstrated photovoltaic characteristics with a short circuit current density of 14.8 mA cm^(-2)and an open-circuit voltage of 0.32 V under 100 mW cm^(-2)*** fill factor and energy conversion efficiency were 53%and 2.46%,respectively,with the highest external quantum efficiency at 530 nm being 44%.

关键词： MoS_(2)monolayers chemical vapor deposition Schottky solar cell

VISCOMETRIC INVESTIGATIONS OF POLYVINYLPYRROLIDONE IN MIXED SOLVENTS AND WITH VARYING TEMPERATURE

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Chinese Journal of Polymer Science 2005年第4期23卷 367-371页

作者： omar Melad omar Abu-Tiem Rajai Baraka Chemistry Department

The viscosity behavior of polyvinylpyrrolidone(PVP)has been determined at 25℃ in mixed solvents comprising water/dimethylformamide(DMF)and water/methanol(MeOH).Analysis of the data has considered the PVP as being both host and guest polymer in *** intrinsic viscosity of PVP in DMF is higher than in water and in MeOH,but also increases in a mixed solvent with high water content because of the effect of polymer-solvent *** was also found that the intrinsic viscosity of PVP at finite concentration,[η_(pvp)]_c decreases with an increase in the concentration of PVP in *** viscosity behavior of PVP in a mixed solvent is affected by the concentration-dependent intermolecular excluded volume effect,which can be quantitatively expressed by the parameter,b_Y,which reflects the shrinkage of PVP chain coils,resulting in a decrease of[η_(pvp)]_*** effect of temperature on the viscosity behavior of PVP in MeOH shows that the interaction parameter increases up to a maximum value,and then decreases after a certain temperature.

关键词： Polyvinylpyrrolidone Intermolecular excluded volume effect Intrinsic viscosity

Reintegrating nanogranitoid inclusion composition to reconstruct the prograde history of melt-depleted rocks

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Geoscience Frontiers 2019年第2期10卷 517-525页

作者： omar Bartoli Department of Geosciences University of Padova

A recent fascinating development in the study of high-grade metamorphic basements is represented by the finding of tiny inclusions of crystallized melt(nanogranitoid inclusions) hosted in peritectic phases of migmatites and granulites. These inclusions have the potential to provide the primary composition of crustal melts at the source. A novel use of the recently-published nanogranitoid compositional database is presented here. Using granulites from the world-renowned Ivrea Zone(NW Italy) on which the original melt-reintegration approach has been previously applied, it is shown that reintegrating melt inclusion compositions from the published database into residual rock compositions can be a further useful method to reconstruct a plausible prograde history of melt-depleted rocks. This reconstruction is fundamental to investigate the tectonothermal history of geological terranes.

关键词： Nanogranitoids Melt-reintegration Granulite High-temperature metamorphism

Power Reallocation and Complexity Enhancement for Beyond 4G Systems

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China Communications 2019年第6期16卷 114-128页

作者： omar Daoud Communications and Electronics Engineering Department Philadelphia University

Competitiveness in the modern wireless systems’provided services is a key factor in the development,in addition to the adaptation to/harmonization of user ***,this paper discussed the quality of services from the point of view of the need for supporting the needed data *** this purpose,a benchmark based on Multi-Antenna Multiband Orthogonal Frequency Division Multiplexing has been proposed to compatible with Ultra-Wideband systems such as the fifth generation based *** order to enhance the system quality of service,the structure of the ultra-wideband system’s main stage;namely Orthogonal Frequency Division Multiplexing has been modified by imposing a low complexity designed Haar-wavelets stage instead of the fast Fourier transform *** is in addition to reallocate the transmitted power in order to reduce the effect of one of the main drawbacks that is found in the Orthogonal Frequency Division Multiplexing;namely the peak-to-average power ratio problem.A MATLAB simulation has been performed in order to validate the propositions that have been made based on six different performance *** a result,the new propositions were achieved our targets by reducing the system’s complexity in terms of mathematical operations and by giving promising results in managing the transmitted ***,the effectiveness of such work has been verified and compared with four different work in the literature。

关键词： multi antennas-multiband wireless PAPR Haar-DWT power reallocation ACLR EVM

Enhance Vertical Handover Security During Execution Phase in Mobile Networks

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Computers, Materials & Continua 2022年第8期72卷 3863-3875页

作者： omar Khattab Department of Computer Science and Engineering Kuwait College of Science and Technology(KCST)Kuwait

The Vertical Handover(VHO)is one of the most vital features provided for the heterogeneous mobile *** allows Mobile Users(MUs)to keep ongoing sessions without disruption while they continuously move between different Radio Access Technologies(RATs)such as Wireless Fidelity(Wi-Fi),Global System for Mobile Communication(GSM),Universal Mobile Telecommunications System(UMTS),Long Term Evolution(LTE)and Fifth Generation(5G).In order to fulfill this goal,the VHO must comply to three main phases:starting of collecting the required information and then passing it for decision phase to obtain the best available RAT for performing VHO by execution phase ***,the execution phase still encounters some security issues which are exploited by hackers in launching malicious attacks such as ransomware,fragmentation,header manipulation,smurf,host initialization,reconnaissance,eavesdropping,Denial of Service(DoS),spoofing,Man in the Middle(MITM)and *** paper thoroughly studies the recent security issues for hundreds VHO approaches found in the literature and comes up with a secure procedure to enhance VHO security during execution phase.A numerical analysis results of the proposed procedure are effectively evaluated in terms of security and signaling *** with the recent related work found in literature,the analysis demonstrates that the security is successfully improved by 20%whereas signaling cost is maintained as in non-proposed procedure.

关键词： Vertical handover security mobile networks wireless networks heterogeneous wireless networks

A Hybrid Model Using Bio-Inspired Metaheuristic Algorithms for Network Intrusion Detection System

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Computers, Materials & Continua 2021年第7期68卷 409-429页

作者： omar Almomani Department of Computer Network and Information Systems The World Islamic Sciences and Education UniversityAmman11947Jordan

Network Intrusion Detection System(IDS)aims to maintain computer network security by detecting several forms of attacks and unauthorized uses of applications which often can not be detected by *** features selection approach plays an important role in constructing effective network *** bio-inspired metaheuristic algorithms used to reduce features to classify network traffic as abnormal or normal traffic within a shorter duration and showing more ***,this paper aims to propose a hybrid model for network IDS based on hybridization bio-inspired metaheuristic algorithms to detect the generic *** proposed model has two objectives;The first one is to reduce the number of selected features for Network *** objective was met through the hybridization of bioinspired metaheuristic algorithms with each other in a hybrid *** algorithms used in this paper are particle swarm optimization(PSO),multiverse optimizer(MVO),grey wolf optimizer(GWO),moth-flame optimization(MFO),whale optimization algorithm(WOA),firefly algorithm(FFA),and bat algorithm(BAT).The second objective is to detect the generic attack using machine learning *** objective was met through employing the support vector machine(SVM),C4.5(J48)decision tree,and random forest(RF)***-NB15 dataset used for assessing the effectiveness of the proposed hybrid ***-NB15 dataset has nine attacks *** generic attack is the highest among ***,the proposed model aims to identify generic *** data showed that J48 is the best classifier compared to SVM and RF for the time needed to build the *** terms of features reduction for the classification,my data show that the MFO-WOA and FFA-GWO models reduce the features to 15 features with close accuracy,sensitivity and F-measure of all features,whereas MVO-BAT model reduces features to 24 features with the same accuracy,sensitivity and F-measure of all features for all classifiers.

关键词： IDS metaheuristic algorithms PSO MVO GWO MFO WOA FFA BAT SVM J48 RF UNSW-NB15 dataset

A Dynamic Management Scheme for Internet of Things(IoT)Environments:Simulation and Performance Evaluation

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Computer Modeling in Engineering & Sciences 2022年第12期133卷 673-695页

作者： omar Said Department of Information Technology College of Computers and Information TechnologyTaif UniversityP.O.Box 11099Taif21944Saudi Arabia

In recent years,the Internet of Things(IoT)technology has been considered one of the most attractive fields for researchers due to its aspirations and implications for society and life as a *** IoT environment contains vast numbers of devices,equipment,and heterogeneous users who generate massive amounts of ***,things’entry into and exit fromIoT systems occur dynamically,changing the topology and content of IoT networks very ***,managing IoT environments is among the most pressing *** paper proposes an adaptive and dynamic scheme for managing IoT environments is *** management scheme depends on the use of previous management methodologies,considering two main *** first factor is network status,which is determined in *** second factor is a management method’s suitability according to its desired *** test the proposed management scheme,a simulation environment is created using *** metrics used to measure the management scheme performance are bandwidth consumption,energy consumption,packet loss,throughput,delay,usage rate of individualmanagement techniques,and *** simulation results prove that the proposed management scheme outperformed the individual 6LowPANSNMP,CoAP,and LWM2M management schemes.

关键词： Internet of Things IoT management IoT simulation SNMP neural networks big data

Performance Analysis of the Reconfigurable Intelligent Surfaces Communication Systems

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Journal of Communications and Information Networks 2024年第2期9卷 184-191页

作者： omar Abu Ella Department of Electrical and Electronic Engineering Misurata University2659 Zawiat AlmahjoubMisurataLibya

Reconfigurable intelligent surfaces (RIS) play a vital role in meeting the growing demand for higher data rates and reliability in wireless systems. This study focuses on analyzing the performance of RIS systems to gain a deeper understanding of their *** paper presents a mathematical analysis of the RIS system,deriving closed-form formulae that express its characteristics including signal-to-noise ratio(SNR)distribution,ergodic and effective capacity,outage,and error probability. The obtained formulae are newly derived and unconditionally valid solutions. Numerical results demonstrate a close agreement between the derived formulae and MonteCarlo simulation outcomes.

关键词： ergodic capacity effective capacity outage probability bit error rate Rayleigh fading channel RISassisted communication system