Robust and Intelligent Control for Single-stage Grid-Connected Modular Multilevel Converter in PV Applications

Hafez Ahmed A.,Mahmoud Alaa A.,Yousef Ali M. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.2

Renewable Energy Resources (RESs) are frequently interfaced to the loads/grid via the standard two/three-level inverters. These inverter circuits to comply with the utility regulations must use volumetric and cumbersome fi ltering arrangements. Therefore, this article advises the application of Modular Multilevel Converter (MMC) for interfacing RESs in stand-alone and/or grid-connected operating modes. The MMC off ers high quality voltage/current/power waveforms without additional fi ltering requirements, which possibly reduce the size/cost of the interfacing circuits. A simple and innovative active and reactive power control is proposed to drive the proposed MMC such that PV arrays operate at Maximum Power Point (MPP) under diff erent climatological operating conditions. The proposed active-reactive control is implemented via Proportional Integral (PI) controllers; their parameters are defi ned via constraint optimization. Genetic Algorithm (GA) is used in this research to confi gure the PIs of the main controller. The objective function was designed to increase the stability margins of the system while reducing the overshoot. The proposed MMC has an extra freedom degree of generating/absorbing reactive power. The static and dynamic performances of MMC are analyzed via MATLAB and its dynamic platform, Simulink. The results showed that the proposed MMC produced signifi cantly lower Total Harmonic Distortion (THD) than the three-level inverters. The static performance of the MMC showed that the THD decreases signifi cantly with the increase of the converter level/sub-module number. The results raveled the robustness and eff ectiveness of the proposed controller, such that the PV generator operates at MPP while introducing high quality power/voltage to the loads/grid.

MicroRNAs and Metastasis-related Gene Expression in Egyptian Breast Cancer Patients

Hafez, Mohamed M.,Hassan, Zeinab K.,Zekri, Abdel Rahman N.,Gaber, Ayman A.,Rejaie, Salem S. Al,Sayed-Ahmed, Mohamed M.,Shabanah, Othman Al Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.2

Aim and background: MicroRNAs (miRNAs) are a class of naturally occurring small noncoding RNAs that regulate gene expression, cell growth, differentiation and apoptosis by targeting mRNAs for translational repression or cleavage. The present study was conducted to study miRNAs in Egyptian breast cancer (BC) and their relation to metastasis, tumor invasion and apoptosis in addition to their association with the ER and PR statuses. Methods: Real Time RT-PCR was performed to identify the miRNA expression level of eight miRNAs and eight metastatic-related genes in 40 breast cancer samples and their adjacent non-neoplastic tissues. The expression levels of each miRNA relative to U6 RNA were determined using the $^{2-{\Delta}}CT$ method. Also, miRNA expression profiles of the BC and their corresponding ANT were evaluated. Results: The BC patients showed an up-regulation in miRNAs (mir-155, mir-10, mir-21 and mir-373) with an upregulation in MMP2, MMp9 and VEGF genes. We found down regulation in mir-17p, mir-126, mir-335, mir-30b and also TIMP3, TMP1 and PDCD4 genes in the cancer tissue compared to the adjacent non-neoplastic tissues. Mir -10b, mir -21, mir-155 and mir373 and the metastatic genes MMP2, MMP9 and VEGF were significantly associated with an increase in tumor size (P < 0.05). No significant difference was observed between any of the studied miRNAs regarding lymph node metastasis. Mir-21 was significantly over-expressed in ER-/PR-cases. Conclusion: Specific miRNAs (mir-10, mir-21, mir-155, mir-373, mir-30b, mir-126, mir-17p, mir-335) are associated with tumor metastasis and other clinical characteristics for BC, facilitating identification of individuals who are at risk.

Increased Hypermethylation of Glutathione S-Transferase P1, DNA-Binding Protein Inhibitor, Death Associated Protein Kinase and Paired Box Protein-5 Genes in Triple-Negative Breast Cancer Saudi Females

Hafez, Mohamed M.,Al-Shabanah, Othman A.,Al-Rejaie, Salim S.,Al-Harbi, Naif O.,Hassan, Zeinab K.,Alsheikh, Abdulmalik,Theyab, Abdurrahman I. Al,Aldelemy, Meshan L.,Sayed-Ahmed, Mohamed M. Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.2

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer (BC) with higher metastatic rate and both local and systemic recurrence compared to non-TNBC. The generation of reactive oxygen species (ROS) secondary to oxidative stress is associated with DNA damage, chromosomal degradation and alterations of both hypermethylation and hypomethylation of DNA. This study concerns differential methylation of promoter regions in specific groups of genes in TNBC and non-TNBC Saudi females in an effort to understand whether epigenetic events might be involved in breast carcinogenesis, and whether they might be used as markers for Saudi BCs. Methylation of glutathione S-transferase P1 (GSTP1), T-cadherin (CDH13), Paired box protein 5 (PAX5), death associated protein kinase (DAPK), twist-related protein (TWIST), DNA-binding protein inhibitor (ID4), High In Normal-1 (HIN-1), cyclin-dependent kinase inhibitor 2A (p16), cyclin D2 and retinoic acid receptor-${\beta}$ ($RAR{\beta}1$) genes was analyzed by methylation specific polymerase chain reaction (MSP) in 200 archival formalin-fixed paraffin embedded BC tissues divided into 3 groups; benign breast tissues (20), TNBC (80) and non-TNBC (100). The relationships between methylation status, and clinical and pathological characteristics of patients and tumors were assessed. Higher frequencies of GSTP1, ID4, TWIST, DAPK, PAX5 and HIN-1 hypermethylation were found in TNBC than in non-TNBC. Hypermethylation of GSTP1, CDH13, ID4, DAPK, HIN-1 and PAX5 increased with tumor grade increasing. Other statistically significant correlations were identified with studied genes. Data from this study suggest that increased hypermethylation of GSTP1, ID4, TWIST, DAPK, PAX5 and HIN-1 genes in TNBC than in non-TNBC can act as useful biomarker for BCs in the Saudi population. The higher frequency of specific hypermethylated genes paralleling tumor grade, size and lymph node involvement suggests contributions to breast cancer initiation and progression.

SKP2/P27^Kip1 pathway is associated with Advanced Ovarian Cancer in Saudi Patients

Hafez, Mohamed M,Alhoshani, Ali R,Al-Hosaini, Khaled A,Alsharari, Shakir D,Al Rejaie, Salim S,Sayed-Ahmed, Mohamed M,Al-Shabanah, Othman A Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.14

Background: Ovarian cancer is the most common gynecological malignancy and constitutes the fifth leading cause of female cancer death. Some biological parameters have prognostic roles in patients with advanced ovarian cancer and their expression may contribute to tumor progression. The aim of this study was to investigate the potential prognostic value of SKP2, genes P27Kip1, K-ras, c-Myc, COX2 and HER2 genes expression in ovarian cancer. Materials and Methods: This study was performed on two hundred formalin fixed paraffin embedded ovarian cancer and normal adjacent tissues (NAT). Gene expression levels were assessed using real time PCR and Western blotting. Results: Elevated expression levels of SKP2, K-ras, c-Myc, HER2 and COX2 genes were observed in 61.5% (123/200), 92.5% (185/200), 74% (148/200), 96 % (192/200), 90% (180/200) and 78.5% (157/200) of cancer tissues, respectively. High expression of SKP2 and down-regulation of P27 was associated with advanced stages of cancer. Conclusions: The association between high expression of c-Myc and SKP2 with low expression of P27 suggested that the Skp2-P27 pathway may play an important role in ovarian carcinogenesis. Reduced expression of P27 is associated with advanced stage of cancer and can be used as a biological marker in clinical routine assessment and management of women with advanced ovarian cancer.

Molecular Prognostic Profile of Egyptian HCC Cases Infected with Hepatitis C Virus

Zekri, Abdel-Rahman N.,Hassan, Zeinab K.,Bahnassy, Abeer A.,Sherif, Ghada M.,ELdahshan, Dina,Abouelhoda, Mohamed,Ali, Ahmed,Hafez, Mohamed M. Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.11

Background: Hepatocellular carcinoma (HCC) is a common and aggressive malignancy. Despite of the improvements in its treatment, HCC prognosis remains poor due to its recurrence after resection. This study provides complete genetic profile for Egyptian HCC. Genome-wide analyses were performed to identify the predictive signatures. Patients and Methods: Liver tissue was collected from 31 patients with diagnosis of HCC and gene expression levels in the tumours and their adjacent non-neoplastic tissues samples were studied by analyzing changes by microarray then correlate these with the clinico-pathological parameters. Genes were validated in an independent set by qPCR. The genomic profile was associated with genetic disorders and cancer focused on gene expression, cell cycle and cell death. Molecular profile analysis revealed cell cycle progression and arrest at G2/M, but progression to mitosis; unregulated DNA damage check-points, and apoptosis. Result: Nine hundred fifty eight transcripts out of the 25,000 studied cDNAs were differentially expressed; 503 were up-regulated and 455 were down-regulated. A total of 19 pathways were up-regulated through 27 genes and 13 pathways were down-regulated through 19 genes. Thirty-seven genes showed significant differences in their expression between HCC cases with high and low Alpha Feto Protein ($AFP{\geq}600$ IU/ml). The validation for the microarray was done by real time PCR assay in which PPP3CA, ATG-5, BACE genes showed down-regulation and ABCG2, RXRA, ELOVL2, CXR3 genes showed up-regulation. cDNA microarrays showed that among the major upregulated genes in HCC are sets. Conclusion: The identified genes could provide a panel of new diagnostic and prognostic aids for HCC.