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Rezk, Abdelrahman I.,Obiweluozor, Francis O.,Choukrani, Ghizlane,Park, Chan Hee,Kim, Cheol Sang ELSEVIER 2019 INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES Vol.141 No.-
<P><B>Abstract</B></P> <P>A pH-sensitive polymeric carrier was developed in this study for local delivery of anticancer drug bortezomib (BTZ) to cancer cells. Our strategy is based on the conjugation of BTZ to polymeric carriers containing catechol groups, which are considered to release BTZ selectively in cancer cells. In this study we used alginate-conjugated polydopamine as a building block polymer. The catechol moiety of polydopamine binds to the boronic acid group of BTZ drug and release the drug molecules in a pH-dependent method. Cancer tissue has acidic environment where BTZ dissociate from the catechol group of polydopamine to control the release of the free drug. Mathematical equation models were used to clarify the mechanism of drug release. The release profile fitted first order with correlation coefficient (R<SUP>2</SUP> = 0.98), the release mechanism was studied using Korsmeyer–Peppas, Higuchi, Hixson-Crowell, and Kopcha models. We revealed the release mechanism follows non-fickian and diffusion was the dominant mechanism while small portion contributed to erosion. The pH-sensitive mechanism controls the release of BTZ in targeted cancer cells, hence developing a novel idea that is applicable in future towards other boronic acid-containing drugs to treat various kinds of health challenges.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The AlgPD-BTZ hydrogel presented a chemo selective approach for cancer chemotherapy. </LI> <LI> Sustained release profile of BTZ in pH dependent manner </LI> <LI> In-depth study of kinetics and mechanism of drug release </LI> <LI> The AlgPD-BTZ hydrogel shows remarkable cytotoxicity to cancer cells. </LI> </UL> </P>
Application of Reliability Centered Maintenance Strategy to Safety Injection System for APR1400
Rezk, Osama,Jung, JaeCheon,Lee, YongKwan The Korean Society of Systems Engineering 2016 시스템엔지니어링학술지 Vol.12 No.1
Reliability Centered Maintenance (RCM) introduces a systematic method and decision logic tree for utilizing previous operating experience focused on reliability and optimization of maintenance activities. In this paper RCM methodology is applied on safety injection system for APR-1400. Functional Failure Mode Effects and Criticality Analysis (FME&CA) are applied to evaluate the failure modes and the effect on the component, system and plant. Logic Tree Analysis (LTA) is used to determine the optimum maintenance tasks. The results show that increasing the condition based maintenance will reduce component failure and improve reliability and availability of the system. Also the extension of the surveillance test interval of Safety Injection Pumps (SIPs) would lead to an improved pump's availability, eliminate the unnecessary maintenance tasks and this will optimize maintenance activities.
Rezk, Abdelrahman I.,Rajan Unnithan, Afeesh,Hee Park, Chan,Sang Kim, Cheol Elsevier 2018 Chemical engineering journal Vol.350 No.-
<P><B>Abstract</B></P> <P>Multilayer nanofibrous scaffolds are gaining great attention in biomedical fields especially as tissue regeneration materials as well as drug delivery devices. Herein, we report the unique design of a tri-layered composite nanofiber scaffold mimicking the bone ECM for bone tissue regeneration. The tri-layered membrane consists of a superficial layer of PVA-PVAc loaded with simvastatin to initiate and improve osteogenesis process via sustained release of the drug as well as the excellent bioactivity of its blended polymers. The PCL-CA-β-tcp middle layer acts as a platform for stimulating the bio mineralization process mimicking the apatite like layer which mainly start after the first week of implantation. The final PCL layer performs as the fundamental layer to keep mechanical properties of the composite mat. The as prepared scaffolds were investigated in terms of morphology characterization, physiochemical properties, biomimetic mineralization, drug release and biocompatibility. The <I>in vitro</I> drug release study confirms the sustained release of simvastatin from the tri-layered membrane by obeying the Korsemeyer-Peppas, Higushi model and Kopcha model. The results demonstrate that the proposed biocompatible tri-layered scaffold will be a promising future material for bone tissue regeneration application by providing higher mineralization, enhanced cell attachment and proliferation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Unique design of a tri-layered composite nanofiber scaffold mimicking the bone ECM. </LI> <LI> Single scaffold for bone regeneration and osteogenic drug delivery. </LI> <LI> Composite nanofiber enhanced osteoblast cell adhesion and proliferation. </LI> <LI> Potential platform for stimulating the biomineralization process. </LI> <LI> Drug release by obeying the Korsemeyer-Peppas and Kopcha model. </LI> </UL> </P>
In-Use Compliance Emission Testing Analysis Applied in LabVIEW for Engineers
( Ghaly Rezk Mikhail ),( Chun Beom Lee ),( Seong Joo Choi ) 한국실천공학교육학회 2014 실천공학교육논문지 Vol.6 No.2
Analyzing test data of a vehicle for evaluating its emission performance is an essential process in automotive development field, yet it is intricate and tedious task. In addition, clear understanding and care are required when the analysis process is carried out. Computer software solutions significantly reduce the time and the effort for such analysis. Developing a computer routine to analyze the emission data in a vehicle test demands a complete understanding of the emissions analysis and its related details. In this paper, the principals to develop a LabVIEW analysis routine (VI) are introduced helping automotive engineers comprehend the emission analysis process of a vehicle test data and instruct them to develop similar routines for such analysis.
In-Use Compliance Emission Testing Analysis Applied in LabVIEW for Engineers
Mikhail, Ghaly-Rezk,Lee, Chun-Beom,Choi, Seong-Joo Korean Institute for Pratical Engineering Educatio 2014 실천공학교육논문지 Vol.6 No.2
Analyzing test data of a vehicle for evaluating its emission performance is an essential process in automotive development field, yet it is intricate and tedious task. In addition, clear understanding and care are required when the analysis process is carried out. Computer software solutions significantly reduce the time and the effort for such analysis. Developing a computer routine to analyze the emission data in a vehicle test demands a complete understanding of the emissions analysis and its related details. In this paper, the principals to develop a LabVIEW analysis routine (VI) are introduced helping automotive engineers comprehend the emission analysis process of a vehicle test data and instruct them to develop similar routines for such analysis.
A Study on Non Destructive Evaluation of the Steam Turbine L-0 Blades
Mizanur, Rahman Md.,Rezk, Osama,Ouma, Victor Otieno,Vaysidin, Saidov,Gomaa, M. Abdullatif,Jung, JaeCheon,Lee, YongKwan The Korean Society of Systems Engineering 2016 시스템엔지니어링학술지 Vol.12 No.1
The Nuclear and Fossil Steam Turbines record a considerable number of failures annually. Some of these failures reported are as result of blade failure. The failure of the L-0 blade in a Steam Turbine is one of the most reported blade failure in Nuclear and Fossil steam turbines. This paper seeks to identify the best Non Destructive Evaluation (NDE) method or methods to be used in the steam turbine L-0 blades inspection process. The development of systems engineering processes presents an opportunity to apply NDE inspection to the L-0 blades. This process apply computer modelling of the L-0 using ANSYS and by simulating the stresses experienced by the L-0 blade during operation it is possible to identify the most susceptible areas for crack formation and growth. The results from these models compared to industry data for validation. The analysis of these results used to predict the most probable failure location and failure modes. Therefore NDE inspection can be applied to these areas with greater degree of accuracy. This would be beneficial in the increasing the accuracy in the detection of cracks and hence save inspection time and the overall inspection cost. Furthermore, not only the location for crack formation and NDE inspection determined but also best the NDE inspection technique/techniques to be applied appropriately on the L-0 blade are prescribed.
Effect of Berm Properties on Non-Cohesive Earth Dam Failure due to Overtopping
Shaimaa Aman,Mohamed Abdelrazek Rezk,Rabiea Nasr 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5
Berms are typically built on the upstream and downstream slopes of earth dams to provide slope stability against seepage. The influence of berm properties on dam stability is widely studied in much research. The most important thing during dam failure by overtopping is to delay its failure and reduce maximum outflow discharge to give the region downstream chance to evacuate. In this paper, the effect of cutting berm with varying widths and heights on the erosion process, delaying the dam failure and reducing maximum outflow discharge during an overtopping event is experimentally investigated. The mean goal is to find the optimum berm width and height which give the best results of time of dam failure and maximum outflow discharge. To fulfill this goal many experiments are conducted and for each one, the erosion process, the time of dam failure, maximum outflow discharge and its time are measured and analyzed. In addition, two experiments lining the downstream slope are performed. The results revealed that constructing a berm with relative width equal to 0.33 and a relative height equal to 0.5, increases the time of dam failure by 12.5%, decreases the maximum outflow discharge by 2.22%, and increases the time to maximum outflow discharge by 25%. Also, it is found that the relative berm height ranges from 0.5 to 0.67 gives the optimum results. However, it is found that lining the upper part of the downstream slope and crest improves the results for relative berm heights less than 0.5. Lining significantly increases the time of dam failure by four times more than the case without lining and greatly delays the occurrence of maximum outflow discharge.
한국어 워드넷 연결과 웹 자원 접근성 개선에 의한 디비피디아 강화
임경태(KyungTae Lim),함영균(YoungGyun Hahm),마틴(Martin Rezk),박정열(Jungyeul Park),윤용운(Yongun Yoon),최기선(Key-Sun Choi) 한국정보과학회 2013 정보과학회 컴퓨팅의 실제 논문지 Vol.19 No.9
본 논문에서는 한국어 디비피디아의 웹 자원 접근성 개선과 한국어 워드넷 연결을 통한 한국어 디비피디아 활용도를 높이는 방안을 제시한다. 이를 통해, 한국어 디비피디아는 사람이 읽을 수 있는 상태의 리소스 페이지 제공이 가능하다. 한편, 한국어 워드넷인 코어넷과 한국어 디비피디아와의 연결을 통해 디비피디아로부터 접근 가능한 단어의 범위를 확장하였다. 한국어 디비피디아-코어넷 연동은 유사도 계산에 의해서 92%의 연결 정확도를 보였고 오류 분석을 시도하였다. In this paper, we find a way to make good use of Korean DBpedia by improving web access to Korean DBpedia resources and linking Korean Word Net called CoreNet. Current Korean DBpedia can generate a human readable resource page. We also increase the number of accessible words by linking CoreNet and Korean DBpedia. By measuring similarity between CoreNet and Korean DBpedia the linking accuracy is up to 92% and we analyze remaining errors.