Virulence Attenuation of Pectobacterium carotovorum Using N-Acyl-homoserine Lactone Degrading Bacteria Isolated from Potato Rhizosphere

Mahmoudi, Esmaeil,Tabatabaei, Badraldin Ebrahim Sayed,Venturi, Vittorio The Korean Society of Plant Pathology 2011 Plant Pathology Journal Vol.27 No.3

Several soil bacteria were found to degrade N-Acylhomoserine lactones (NAHLs), thereby interfering with the bacterial quorum sensing system. In this research, fifteen strains of NAHL degrading rhizobacteria were isolated from potato rhizosphere. Based on phenotypic characteristics and 16S rDNA sequence analyses, the strains were identified as members of genera Bacillus, Streptomyces, Arthrobacter, Pseudomonas and Mesorhizobium. All tested isolates were capable to degrade both synthetic and natural NAHL produced by Pectobacterium carotovorum subsp. carotovorum (Pcc) strain EMPCC. In quorum quenching experiments selected isolates, especially Mesorhizobium sp., were markedly reduced the pathogenicity of Pcc strain EMPCC in potato tubers and totally suppressed tissue maceration on potato tubers. These led to consider the latter as a useful biocontrol agent against Pectobacterium spp.

SR-ADDITIVE CODES

Mahmoudi, Saadoun,Samei, Karim Korean Mathematical Society 2019 대한수학회보 Vol.56 No.5

In this paper, we introduce SR-additive codes as a generalization of the classes of ${\mathbb{Z}}_{p^r}{\mathbb{Z}}_{p^s}$ and ${\mathbb{Z}}_2{\mathbb{Z}}_2[u]$-additive codes, where S is an R-algebra and an SR-additive code is an R-submodule of $S^{\alpha}{\times}R^{\beta}$. In particular, the definitions of bilinear forms, weight functions and Gray maps on the classes of ${\mathbb{Z}}_{p^r}{\mathbb{Z}}_{p^s}$ and ${\mathbb{Z}}_2{\mathbb{Z}}_2[u]$-additive codes are generalized to SR-additive codes. Also the singleton bound for SR-additive codes and some results on one weight SR-additive codes are given. Among other important results, we obtain the structure of SR-additive cyclic codes. As some results of the theory, the structure of cyclic ${\mathbb{Z}}_2{\mathbb{Z}}_4$, ${\mathbb{Z}}_{p^r}{\mathbb{Z}}_{p^s}$, ${\mathbb{Z}}_2{\mathbb{Z}}_2[u]$, $({\mathbb{Z}}_2)({\mathbb{Z}}_2+u{\mathbb{Z}}_2+u^2{\mathbb{Z}}_2)$, $({\mathbb{Z}}_2+u{\mathbb{Z}}_2)({\mathbb{Z}}_2+u{\mathbb{Z}}_2+u^2{\mathbb{Z}}_2)$, $({\mathbb{Z}}_2)({\mathbb{Z}}_2+u{\mathbb{Z}}_2+v{\mathbb{Z}}_2)$ and $({\mathbb{Z}}_2+u{\mathbb{Z}}_2)({\mathbb{Z}}_2+u{\mathbb{Z}}_2+v{\mathbb{Z}}_2)$-additive codes are presented.

Hybrid of the fuzzy logic controller with the harmony search algorithm to PWR in-core fuel management optimization

Mahmoudi, Sayyed Mostafa,Rad, Milad Mansouri,Ochbelagh, Dariush Rezaei Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.11

One of the important parts of the in-core fuel management is loading pattern optimization (LPO). The loading pattern optimization as a reasonable design of the in-core fuel management can improve both economic and safe aspects of the nuclear reactor. This work proposes the hybrid of fuzzy logic controller with harmony search algorithm (HS) for loading pattern optimization in a pressurized water reactor. The music improvisation process to find a pleasing harmony is inspiring the harmony search algorithm. In this work, the adjustment of the harmony search algorithm parameters such as the bandwidth and the pitch adjustment rate are increasing performance of the proposed algorithm which is done through a fuzzy logic controller. Hence, membership functions and fuzzy rules are designed to improve the performance of the HS algorithm and achieve optimal results. The objective of the method is finding an optimum core arrangement according to safety and economic aspects such as reduction of power peaking factor (PPF) and increase of effective multiplication factor (Keff). The proposed approach effectiveness has been tried in two cases, Michalewicz's bivariate function problem and NEACRP LWR core. The results show that by using fuzzy harmony search algorithm the value of the fitness function is improved by 15.35%. Finally, with regard to the new solutions proposed in this research it could be used as a trustworthy method for other optimization issues of engineering field.

Lack of Associations between Vitamin D Metabolism-Related Gene Variants and Risk of Colorectal Cancer

Mahmoudi, Touraj,Karimi, Khatoon,Arkani, Maral,Farahani, Hamid,Nobakht, Hossein,Dabiri, Reza,Asadi, Asadollah,Vahedi, Mohsen,Zali, Mohammad Reza Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.2

Purpose: With regard to the protective effect of vitamin D against colorectal cancer (CRC), we evaluated genetic variants that might influence vitamin D metabolism: vitamin D receptor (VDR), vitamin D binding protein (GC), vitamin D 25-hydroxylase (CYP2R1), and vitamin D 25-hydroxy 1-alpha hydroxylase (CYP27B1). Materials and Methods: A total of 657 subjects, including 303 cases with CRC and 354 controls were enrolled in this case-control study. All 657 were genotyped for the four gene variants using PCR-RFLP methods. Results: In this study, no significant difference was observed for VDR (rs2238136), GC (rs4588), CYP2R1 (rs12794714), and CYP27B1 (rs3782130) gene variants in either genotype or allele frequencies between the cases with CRC and the controls and this lack of difference remained even after adjustment for age, BMI, sex, smoking status, NSAID use, and family history of CRC. Furthermore, no evidence for effect modification of the variants and CRC by BMI, sex, or tumor site was observed. Conclusions: Our findings do not support a role for VDR, GC, and CYP27B1 genes in CRC risk in our Iranian population. Another interesting finding, which to our knowledge has not been reported previously, was the lack of association with the CYP2R1 gene polymorphism. Nonetheless, our findings require confirmation and possible roles of vitamin D metabolism-related genes in carcinogenesis need to be further investigated.

A NEW APPROACH TO SOLVING OPTIMAL INNER CONTROL OF LINEAR PARABOLIC PDES PROBLEM

Mahmoudi, M.,Kamyad, A.V.,Effati, S. The Korean Society for Computational and Applied M 2012 Journal of applied mathematics & informatics Vol.30 No.5

In this paper, we develop a numerical method to solving an optimal control problem, which is governed by a parabolic partial differential equations(PDEs). Our approach is to approximate the PDE problem to initial value problem(IVP) in $\mathbb{R}$. Then, the homogeneous part of IVP is solved using semigroup theory. In the next step, the convergence of this approach is verified by properties of one-parameter semigroup theory. In the rest of paper, the original optimal control problem is solved by utilizing the solution of homogeneous part. Finally one numerical example is given.

Graphene and its derivatives for solar cells application

Mahmoudi, Tahmineh,Wang, Yousheng,Hahn, Yoon-Bong Elsevier 2018 Nano energy Vol.47 No.-

<P><B>Abstract</B></P> <P>Graphene has played the role of game-changer for conductive transparent devices indebted to its unique two dimensional (2D) structures and gained an exceptional opportunity to be employed in energy industry. In the past two decades graphene has been merged with the concept of photovoltaic (PV) material and exhibited a significant role as a transparent electrode, hole/electron transport material and interfacial buffer layer in solar cell devices. This review covers the different methods of graphene fabrication and broadly discusses the recent advances in graphene-based solar cells, including bulk heterojunction (BHJ) organic, dye-sensitized and perovskite solar cell deices. The power conversion efficiency surpassed 20.3% for graphene-based perovskite solar cells and hit the efficiency of 10% for BHJ organic solar cells. Except the part of charge extracting and transport to the electrodes, graphene has another unique role of device protection against environmental degradation via its packed 2D network structure and provides long-term environmental stability for PV devices. We highlighted a comparative study on the role of graphene and its derivatives in photovoltaic devices. After all, the potential issues and the perspective for future research in graphene-based materials for PV applications are presented.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Key works related to graphene-based solar cells are reviewed and critically studied. </LI> <LI> Performance of graphene-based PVs is improved by functionalization, doping and oxidation. </LI> <LI> Flexibility of cells is improved with the use of graphene as transparent conductive electrode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Schematic illustration of graphene and its derivatives for solar cells applications</P> <P>[DISPLAY OMISSION]</P>

Efficient bulk heterojunction hybrid solar cells with graphene-silver nanoparticles composite synthesized by microwave-assisted reduction

Mahmoudi, Tahmineh,Seo, Seunghui,Yang, Hwa-Young,Rho, Won-Yeop,Wang, Yousheng,Hahn, Yoon-Bong Elsevier 2016 Nano energy Vol.28 No.-

<P><B>Abstract</B></P> <P>Herein, we present a simple, eco-friendly one-step microwave-assisted reduction (MWAR) that can produce silver nanoparticles (Ag NPs) and reduced graphene oxide (rGO) in the form of Ag-rGO composites for application in heterojunction hybrid solar cells. The field-effect transistor fabricated with the MWAR Ag-rGO composite showed p-type behavior with a high mobility of 3.3×10<SUP>5</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> and conductivity of 9×10<SUP>6</SUP> S/m which is one-order of magnitude greater than pristine graphene (i.e., 1.59×10<SUP>5</SUP> S/m). As-synthesized Ag-rGO composite was introduced into the active layer of bulk heterojunction solar cell based on P3HT:PCBM. Compared to the P3HT:PCBM only device (i.e., control device), the Ag-rGO implemented device showed a power conversion efficiency (PCE) of 4.23%, which is about 42% increase over the control device (i.e. PCE=2.98%). This dramatic increase in PCE was found to be mainly due to an increase in short-circuit current (<I>J</I> <SUB>sc</SUB>) from 9.55 to 12.76mA/cm<SUP>2</SUP> (about 33% increase), suggesting that the incorporation of p-type Ag-rGO into the active layer enhances the charge carrier generation and fast extraction of holes to the electrode. Furthermore, the Ag-rGO composite based solar cells without encapsulation showed remarkable air stability with retaining ~90% of its original PCE and ~93% of <I>J</I> <SUB>sc</SUB> for 30 days under ambient environment, attributed to gas barrier feature of the randomly distributed graphene sheets.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Eco-friendly microwave-assisted reduction for graphene-silver (Ag-rGO) composite. </LI> <LI> Enhanced charge carrier generation and fast extraction of holes with Ag-rGO composite. </LI> <LI> Substantial enhancement of solar cells performance with P3HT:PCBM:Ag-rGO. </LI> <LI> Higher photocurrent and power conversion efficiency with the inclusion of Ag-rGO. </LI> <LI> Remarkable air stability without encapsulation of the Ag-rGO based hybrid solar cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Schematic illustration of a bulk heterojunction hybrid solar cell based on reduced graphene oxide (rGO)-silver nanoparticles (Ag-rGO) composite in the active layer. The Ag-rGO composite implemented device showed substantial enhancement of device performance, suggesting that the incorporation of Ag-rGO into the active layer enhances the charge carrier generation and fast extraction to the electrode. Furthermore, the Ag-rGO based solar cells without encapsulation showed remarkable air stability under ambient environment.</P> <P>[DISPLAY OMISSION]</P>

Framework for Continuous Assessment and Improvement of Occupational Health and Safety Issues in Construction Companies

Mahmoudi, Shahram,Ghasemi, Fakhradin,Mohammadfam, Iraj,Soleimani, Esmaeil Occupational Safety and Health Research Institute 2014 Safety and health at work Vol.5 No.3

Background: Construction industry is among the most hazardous industries, and needs a comprehensive and simple-to-administer tool to continuously assess and promote its health and safety performance. Methods: Through the study of various standard systems (mainly Health, Safety, and Environment Management System; Occupational Health and Safety Assessment Series 180001; and British Standard, occupational health and safety management systems-Guide 8800), seven main elements were determined for the desired framework, and then, by reviewing literature, factors affecting these main elements were determined. The relative importance of each element and its related factors was calculated at organizational and project levels. The provided framework was then implemented in three construction companies, and results were compared together. Results: The results of the study show that the relative importance of the main elements and their related factors differ between organizational and project levels: leadership and commitment are the most important elements at the organization level, whereas risk assessment and management are most important at the project level. Conclusion: The present study demonstrated that the framework is easy to administer, and by interpreting the results, the main factors leading to the present condition of companies can be determined.

Parathyroid Hormone Gene rs6256 and Calcium Sensing Receptor Gene rs1801725 Variants are not Associated with Susceptibility to Colorectal Cancer in Iran

Mahmoudi, Touraj,Karimi, Khatoon,Arkani, Maral,Farahani, Hamid,Nobakht, Hossein,Dabiri, Reza,Asadi, Asadollah,Zali, Mohammad Reza Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.15

Background: Substantial evidence from epidemiological studies has suggested that increased levels of calcium may play a protective role against colorectal cancer (CRC). Given the vital role of calcium sensing receptor (CaSR) and parathyroid hormone (PTH) in the maintenance of calcium homeostasis, we explored whether the rs1801725 (A986S) variant located in exon 7 of the CaSR gene and the rs6256 variant located in exon 3 of PTH gene might be associated with CRC risk. Materials and Methods: In this study 860 subjects including 350 cases with CRC and 510 controls were enrolled and genotyped using PCR-RFLP methods. Results: We observed no significant difference in genotype or allele frequencies between the cases with CRC and controls for both CaSR and PTH genes either before or after adjustment for confounding factors including age, BMI, sex, smoking status, and family history of CRC. Furthermore, no evidence for effect modification of any association of rs1801725 and rs6256 variants and CRC by BMI, sex, or tumor site was observed. In addition, there was no significant difference in genotype and allele frequencies between the normal weight (BMI < $25kg/m^2$) cases and overweight/obese (BMI ${\geq}25kg/m^2$) cases for the two SNPs. Conclusions: These data indicated that the CaSR gene A986S variant is not a genetic contributor to CRC risk in the Iranian population. Furthermore, our results suggest for the first time that PTH gene variant does not affect CRC risk. Nonetheless, further studies with larger sample size are needed to validate these findings.

Highly conductive and dispersible graphene and its application in P3HT-based solar cells

Mahmoudi, Tahmineh,Rho, Won-Yeop,Yang, Hwa-Young,Silva, S. Ravi P.,Hahn, Yoon-Bong The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.63

<P>A simple reduction method without the need for high-temperature annealing is proposed for highly conductive and dispersible graphene sheets. This method consists of the grafting of graphene oxide (GO) with 1-pyrenecarboxylic acid (PCA) and the exothermic reduction of the PCA-grafted GO, followed by an endothermic decarboxylation with refluxing hot water. The PCA-grafted reduced graphene oxide (PCA-rGO) has a high conductivity of ∼1.52 × 10<SUP>5</SUP> S m<SUP>−1</SUP>. Upon incorporating the rGO-PCA in active and electron transport layers of organic solar cells, compared to P3HT-only devices (0.18%) a 16-fold increase in the power conversion efficiency (2.85%) is obtained, attributed to a substantial increase in the short-circuit current density from 0.017 to 12.09 mA cm<SUP>−2</SUP>.</P> <P>Graphic Abstract</P><P>Structure of an inverted solar cell with the P3HT–PCA-rGO hybrid in the active layer and graphene oxide as the hole transport layer. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc03692a'> </P>