28 results on '"Abbas Mokhtari"'
Search Results
2. Comprehensive review of CRISPR-based gene editing: mechanisms, challenges, and applications in cancer therapy
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Mohammad Chehelgerdi, Matin Chehelgerdi, Milad Khorramian-Ghahfarokhi, Marjan Shafieizadeh, Esmaeil Mahmoudi, Fatemeh Eskandari, Mohsen Rashidi, Asghar Arshi, and Abbas Mokhtari-Farsani
- Subjects
CRISPR system ,Genome editing ,Cancer therapy ,Genetic mutations ,Tumor growth ,Immune response ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract The CRISPR system is a revolutionary genome editing tool that has the potential to revolutionize the field of cancer research and therapy. The ability to precisely target and edit specific genetic mutations that drive the growth and spread of tumors has opened up new possibilities for the development of more effective and personalized cancer treatments. In this review, we will discuss the different CRISPR-based strategies that have been proposed for cancer therapy, including inactivating genes that drive tumor growth, enhancing the immune response to cancer cells, repairing genetic mutations that cause cancer, and delivering cancer-killing molecules directly to tumor cells. We will also summarize the current state of preclinical studies and clinical trials of CRISPR-based cancer therapy, highlighting the most promising results and the challenges that still need to be overcome. Safety and delivery are also important challenges for CRISPR-based cancer therapy to become a viable clinical option. We will discuss the challenges and limitations that need to be overcome, such as off-target effects, safety, and delivery to the tumor site. Finally, we will provide an overview of the current challenges and opportunities in the field of CRISPR-based cancer therapy and discuss future directions for research and development. The CRISPR system has the potential to change the landscape of cancer research, and this review aims to provide an overview of the current state of the field and the challenges that need to be overcome to realize this potential.
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- 2024
- Full Text
- View/download PDF
3. The effectiveness of intervention based on psychological capital on hope, optimism, resilience, and self-efficacy among patients with depression
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Abbas Mokhtari, Mohammad bagher Kajbaf, and Mohammadreza Abedi
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depression ,psychological capital ,hope ,optimism ,resilience ,Psychology ,BF1-990 - Abstract
Background: In the frame of interventional studies, the effectiveness of various psychological interventions on depression has been examined, but no research has been conducted so far with the aim of investigating the effectiveness of intervention based on psychological capital on hope, optimism, resilience, and self-efficacy among patients with depression. Aims: The current research was conducted by the aim of investigating the effectiveness of intervention based on psychological capital on hope, optimism, resilience, and self-efficacy among patients with depression. Method: The present study was conducted by semi-experimental method using a pretest-posttest and control group design. The research population included all the patients with minor to moderate depression referring to Aftab Counseling Center in Najaf Abad, Isfahan, in the first half of 2018. The study sample included 30 depressive patients who were selected by purposeful sampling method and, then, were assigned into two experiment and control groups (15 subjects per group) through random assignment method. The research tools were Beck Depression Inventory (1978) and Psychological Capital Inventory of McGee (2011). The experiment group received the intervention based on psychological capital (Lutthans, Youssef, and Avolio, 2007) in eight 90-minute sessions in group. To analyze the data, univariate analysis of covariance and multivariate analysis of covariance were used. Results: Results indicated that the intervention based on psychological capital was effective on improving psychological capital and the components of hope, optimism, resilience and self-efficacy in depressive patients. Moreover, the training intervention was positively effective on reducing the depression level of patients (p< 0/01). Conclusions: The intervention based on psychological capital can be used as an effective method to increase the potency of hope, self-efficacy, resilience and optimism, and to reduce depressive symptoms in patients with depression.
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- 2021
4. Propose, Analysis and Simulation of an All Optical Full Adder Based on Plasmonic Waves using Metal-Insulator-Metal Waveguide Structure
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Mohsen Olyaee, Mohammad Bagher Tavakoli, and Abbas Mokhtari
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cavity resonator ,mim waveguide ,full-adder ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Applied optics. Photonics ,TA1501-1820 - Abstract
This paper proposes a full adder with minimum power consumption and lowloss with a central frequency of 1550nm using plasmonic Metal-Insulator-Metal (MIM)waveguide structure and rectangular cavity resonator. This full adder operates based onXOR and AND logic gates. In this full adder, the resonant wave composition of the firstand second modes has been used and we have obtained a high transmission coefficientin the states in which the output must be active. This full adder uses the AND and XORlogic gates to be designed with three inputs, which results in the design of a full adderwith lower complexity, lower cost and fewer losses than Other full adders in whichAND and XOR logic gates are combined to be designed with two inputs. The relatedsimulations were performed by FDTD. The obtained results presented a performancesimilar to the predicted models, while considering approximations with theoreticalrelations.
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- 2019
5. Enhanced magnetic properties in ZnCoAlO caused by exchange-coupling to Co nanoparticles
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Qi Feng, Wala Dizayee, Xiaoli Li, David S Score, James R Neal, Anthony J Behan, Abbas Mokhtari, Marzook S Alshammari, Mohammed S Al-Qahtani, Harry J Blythe, Roy W Chantrell, Steve M Heald, Xiao-Hong Xu, A Mark Fox, and Gillian A Gehring
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ZnO ,cobalt nanoparticles ,MCD ,magnetisation ,coercive field ,XAS ,Science ,Physics ,QC1-999 - Abstract
We report the results of a sequence of magnetisation and magneto-optical studies on laser ablated thin films of ZnCoAlO and ZnCoO that contain a small amount of metallic cobalt. The results are compared to those expected when all the magnetization is due to isolated metallic clusters of cobalt and with an oxide sample that is almost free from metallic inclusions. Using a variety of direct magnetic measurements and also magnetic circular dichroism we find that there is ferromagnetism within both the oxide and the metallic inclusions, and furthermore that these magnetic components are exchange-coupled when aluminium is included. This enhances both the coercive field and the remanence. Hence the presence of a controlled quantity of metallic nanoparticles in ZnAlO can improve the magnetic response of the oxide, thus giving great advantages for applications in spintronics.
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- 2016
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6. L'innovation financière dans les pays en voie de développement : les déterminants du mobile banking et du développement financier en Afrique
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Mohamed Amine LOUKILI and Abbas MOKHTARI
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Cette étude aborde les questions d'innovation financière dans les pays en développement en se concentrant sur les déterminants du développement du mobile banking en Afrique. Collecter des données sur le mobile banking dans différents pays par le biais d'institutions et d'organisations nationales et internationales sur la zone géographique de l'étude (Afrique sub-saharienne) afin d'étudier les déterminants du développement du mobile banking. L'analyse théorique montre qu'il existe une corrélation positive entre les différents indicateurs du mobile banking et les indicateurs de développement du mobile banking. Dans l'ensemble, les estimations des quatre modèles mettent en évidence les déterminants suivants : développement du capital humain, politique monétaire fiable, développement des infrastructures, facilitation des transferts de fonds, urbanisation, ouverture commerciale et promotion de l'accès des banques au crédit domestique. En outre, les résultats de notre vérification de robustesse ne sont pas controversés. La recommandation générale aux gouvernements africains est qu'ils devraient rechercher de bonnes performances en mettant en œuvre des politiques économiques spécifiques et bien conditionnées basées sur les déterminants mis en évidence ci-dessus. Mots clés : finance mobile, mobile banking, innovation financière, inclusion financière, Afrique. Classification JEL : G11, G21, O31, O55 Type de l’article : article théorique., This study addresses issues of financial innovation in developing countries by focusing on the determinants of mobile banking development in Africa. Collecting data on mobile banking in different countries through national and international institutions and organizations in the geographical area of the study (Sub-Saharan Africa) in order to investigate the determinants of mobile banking development. The theoretical analysis shows that there is a positive correlation between the different mobile banking indicators and the mobile banking development indicators. Overall, the estimates of the four models point to the following determinants: human capital development, reliable monetary policy, infrastructure development, facilitation of remittances, urbanization, trade openness and promotion of banks' access to domestic credit. Furthermore, the results of our robustness check are not controversial. The general recommendation to African governments is that they should seek good performance by implementing specific and well-conditioned economic policies based on the determinants highlighted above. Keywords: mobile finance, mobile banking, financial innovation, financial inclusion, Africa. JEL Classification: G11, G21, O31, O55 Paper type: Theoretical Research
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- 2022
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7. Biodegradation of Carbon‐Based Nanomaterials: The Importance of 'Biomolecular Corona' Consideration (Adv. Funct. Mater. 6/2022)
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Abbas Mokhtari‐Farsani, Masoud Hasany, Iseult Lynch, and Mehdi Mehrali
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Biomaterials ,Electrochemistry ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
8. Biodegradation of Carbon‐Based Nanomaterials: The Importance of 'Biomolecular Corona' Consideration
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Iseult Lynch, Abbas Mokhtari-Farsani, Mehdi Mehrali, and Masoud Hasany
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Biomaterials ,Corona (optical phenomenon) ,Materials science ,Biocompatibility ,Carbon based nanomaterials ,Electrochemistry ,Nanotechnology ,Biodegradation ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Abstract
It has been over a decade since oxidative enzymes were first used to degrade carbon-based nanomaterials (CBNs). Although enormous progress has been achieved in this field, many questions and problems remain unresolved that need to be answered to usher these materials toward their true destiny. Nanobioscience researchers now know that ignoring the biomolecular corona (BMC) in nanobiomedical studies, either inadvertently or intentionally, is by no means justified. However, a major drawback to progress is that BMC effects on CBN biodegradation have been omitted from a large number of studies. What's more, many studies in the field have eliminated the BMC source in the relevant experiments. Thus, the most critical question that one needs to probe is whether the BMC and its characteristics affect the biodegradability of CBNs? In this conceptual perspective paper, recent progress and significant research in CBNs biodegradation are summarized. Then, the importance of the BMC and its possible impacts on the biodegradation of CBNs are thoroughly explored as a conceptual guide. Finally, remaining challenges and the direction of future research are provided, and barriers that need to be overcome to advance the field are discussed including recommendations regarding BMC considerations and study design and reporting guidelines.
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- 2021
9. Molecular Characterization of Gyr-A Gene Polymorphism in Salmonella Enterica Serovar Enteritidis Isolated of Egg Shells
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Mohammad Chehelgerdi, Abbas Doosti, and Abbas Mokhtari-Farsani
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0301 basic medicine ,Serotype ,Salmonella ,biology ,030106 microbiology ,medicine.disease_cause ,biology.organism_classification ,Antimicrobial ,Microbiology ,DNA extraction ,03 medical and health sciences ,Restriction enzyme ,030104 developmental biology ,Antibiotic resistance ,medicine ,Parasitology ,Gene ,Bacteria ,Food Science - Abstract
Salmonella is one of the important bacteria in egg and as major source in bacterial infection transfer to human and animals. It has been proven that gyrA gene can mediate in resistance and reduced susceptibility to fluoroquinolones, therefore the aim of the present study was to determine gyrA gene polymorphism in S. enterica ser. Enteritidis isolated from egg shell using PCR-RFLP assay. A total of 300 samples of egg shells were collected from seven aviculture in Chaharmahal Va Bakhtiari province and genomic DNA was extracted using DNA extraction kit. PCR-RFLP assay was used to identification of gyrA gene polymorphism using HinfI and BanI restriction endonuclease enzymes. A total of 85 ser. Enteritidis was detected from 300 samples and gyrA gene was isolated from all 85 positive ser. Enteritidis that out of 85 gyrA gene, 23 samples (27%) and 25 samples (29.4%) were respectively positive for HinfI and BanI enzymes. The results of the present study showed a relatively low prevalence of ser. Enteritidis infection in egg shells, but the rate of gyrA gene mutation was high that is very disturbing. Practical Applications Currently, at least 2610 serovars of S.enterica have been recognized worldwide, and all seem to be capable of causing disease in humans. Therefore, S.enterica remains a microbial threat in terms of standards and food safety, and the use of molecular techniques for analysis of antimicrobial resistance and its reasons in Salmonella spp. specifically S.enterica is of high importance. Our study may provide more insights to design new therapeutic plans including limited use of antimicrobial drugs in human and animals, performing antimicrobial susceptibility tests to select suitable antimicrobial agent, and application of recommended dosage of antibiotic. Also the present study can be used to help guide selection of antimicrobials for use in poultry industry and the treatment of diseases associated with Salmonella spp. especially S. enterica subsp enterica ser. Enteritidis.
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- 2016
10. Analyze and calculation of coupling coefficient based on evanescence field for plasmonic directional coupler structure
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Mohsen Olyaee, Mohammad Bagher Tavakoli, and Abbas Mokhtari
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Physics ,business.industry ,Bandwidth (signal processing) ,Physics::Optics ,Perturbation (astronomy) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,020210 optoelectronics & photonics ,Optics ,law ,Monolayer ,0202 electrical engineering, electronic engineering, information engineering ,Power dividers and directional couplers ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Nonlinear Sciences::Pattern Formation and Solitons ,Waveguide ,Plasmon ,Coupling coefficient of resonators ,Electronic circuit - Abstract
We obtain the calculation of coupling coefficient of plasmonic directional coupler made up of two monolayer waveguides separated in the range of 200 nm for TM mode and we assume each waveguides acts as a perturbation to other waveguide but does not affect the waveguide mode. We simulation the transfer distance respect to normalized frequency in two directions, x and z, values transfer distance a limitation of a bandwidth is suitable for designing of integrated optical circuits and construction of couplers and switches.
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- 2018
11. Determination of the presence of Babesia species in blood samples of cattle, camel and sheep in Iran by PCR
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Arman Koohi, Mohammad Chehelgerdi, Augustino Alfred Chengula, Faham Khamesipour, Abbas Mokhtari-Farsani, and Abbas Doosti
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sheep ,Veterinary medicine ,camel ,Babesia spp ,Anemia ,animal diseases ,Biology ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,Animal science ,blood ,law ,parasitic diseases ,medicine ,Parasite hosting ,lcsh:QH301-705.5 ,Polymerase chain reaction ,business.industry ,Babesiosis ,medicine.disease ,biology.organism_classification ,PCR ,lcsh:Biology (General) ,cattle ,Babesia ,Herd ,Livestock ,Babesia species ,General Agricultural and Biological Sciences ,business - Abstract
Babesia species are protozoan parasites that parasitize the erythrocytes of domestic animals and humans, causing anemia in the host. The parasites cause a zoonotic disease known as babesiosis. Polymerase chain reaction (PCR) has proven to be very sensitive for detecting Babesia in blood samples of affected animals, particular in ruminants. The purpose of the current study was to determine the presence of Babesia spp. in blood samples obtained from 2 cattle, camel and sheep in Iran. In addition, the study aimed at establishing a rapid, reliable, specific and sensitive molecular tool, the polymerase chain reaction (PCR), for the detection of Babesia spp. in ruminants. Blood samples were collected from 372 ruminants (155 cattle, 95 sheep and 122 camel) kept at the Livestock Experimental Station. The animals came from randomly selected herds located in the important livestock-production regions of Iran of Isfahan and Chaharmahal va Bakhtiary during December 2012 to March 2013. PCR was used to detect Babesia spp. in the blood samples whereby an amplified band size of 428 bp was considered positive for Babesia spp. The results show that 7.10% (n= 155), 6.56% (n= 122) and 0.00% (n= 95) of the blood samples from cattle, camel and sheep, respectively, were positive for Babesia spp.. The findings from this study revealed that there were Babesia spp. in blood taken from cattle and camel. To our knowledge, this is the first report to show the presence of Babesia spp. in blood samples of Iranian ruminants in Chaharmahal Va Bakhtiari and Isfahan provinces by PCR. These findings justify the importance of control of and eradication plans for Babesia spp. infection in cattle and camel in Iran. As diagnosis of low-level infections by the parasite is important for epidemiological studies, our findings support the power of PCR test for Babesia spp. detection in blood samples and could be easily used for routine diagnosis.
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- 2015
12. Genotypic and phenotypic study of Lactobacillus species isolated from traditional yogurt and cheese in southwest Iran
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Hamidreza Kabiri and Abbas Mokhtari-Farsani
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- 2014
13. Bovine herpesvirus type 5 in semen samples from bulls in Iran
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Abbas Mokhtari-Farsani, Ali Sharifzadeh, Mohammad-Javad Namazi, and Abbas Doosti
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Male ,endocrine system ,Cattle Diseases ,Semen ,Iran ,Biology ,Virus ,fluids and secretions ,Meningoencephalitis ,Virology ,Animals ,Encephalitis, Viral ,Cloning, Molecular ,Gene ,Pathogen ,Herpesvirus 5, Bovine ,urogenital system ,Herpesviridae Infections ,General Medicine ,biology.organism_classification ,Bovine herpesvirus 1 ,Bovine herpesvirus 5 ,Thymidine kinase ,GenBank ,DNA, Viral ,Cattle - Abstract
Bovine herpesvirus 5 (BoHV-5) is an important pathogen of the central nervous system and has already been described in the genital tract of cattle and in semen. This virus is responsible for sporadic epizootics of fatal meningoencephalitis of calves. The objective of the present study was the identification and characterization of BoHV-5 in semen samples from bulls for the first time in Iran. DNA was extracted from bull semen samples, and the glycoprotein D (gD) gene of BoHV-5 and also the thymidine kinase (tK) gene of bovine herpesvirus 1 (BoHV-1) were amplified by PCR assay. The results showed a high prevalence of BoHV-5 (73.2 %) and BoHV-1 (25.89 %) in Iranian bull semen samples. In addition, in order to identify and compare BoHV-5 isolated from Iranian bulls with other isolates from all over the world, the gD gene of this virus was cloned and sequenced. A BLAST search showed that the sequence of the gD gene of BoHV-5 from Iran was 99 % identical to other sequences in the GenBank database. The present study indicated that semen samples are important transmission sources of BoHV-5 virus in Iranian bulls.
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- 2014
14. Application of multiplex PCR for Rapid and sensitive detection of human papillomaviruses in cervical cancer
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Fateme, Zandnia, Abbas, Doosti, Abbas, Mokhtari-Farsani, Mohammad Taghi, Kardi, and Abolfazl, Movafagh
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Human papillomavirus ,Cervical cancer ,virus diseases ,Original Article ,Biomarker ,Multiplex PCR ,female genital diseases and pregnancy complications - Abstract
Objectives: Reffering to an increase in cervical cancer in the recent years, rapid, sensitive and economical detection of human papillomaviruses (HPVs) as causative agents of cervical cancer is important. The traditional methods for the detection of HPVs in cervical cancer, such as pap smear, suffer from limitation and PCR has a potential to overcome the limitaitons. The purpose of present research work was to identify the five important strains of HPV (16, 18, 31, 33 and 45) simultaneously by Multiplex PCR application. Methods: Study was done on 100 cervical lesions of women. DNA was extracted from specimens by a genomic DNA purification kit. A 5-plex PCR was developed for the simultaneous detection of major HPV. Five pair of new primers was designed for detection of HPV 16, 18, 31, 33 and 45 by Multiplex PCR. Results: Among the 100 evaluated samples, 82 were found positive to HPVs. In the meantime the highest rate of infection was for HPV 16. Also 30 of HPV positive samples had infections with two or more HPV types. Conclusion: Multiplex PCR assay used in present study can provide a rapid, sensitive and economical method for detection of viral infections and is applicable to small volumes of vaginal samples.
- Published
- 2016
15. WITHDRAWN: Presence of Qnr genes related to resistance to quinolones, first-, second-, and third-generation in diarrheagenic Escherichia coli
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Zahra Mohammadalipour, Abbas Doosti, and Abbas Mokhtari-Farsani
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0301 basic medicine ,Nalidixic acid ,medicine.drug_class ,030106 microbiology ,Antibiotics ,Biology ,Quinolone ,medicine.disease_cause ,Virology ,Microbiology ,Ciprofloxacin ,03 medical and health sciences ,Antibiotic resistance ,Plasmid ,medicine ,Ofloxacin ,Escherichia coli ,medicine.drug - Abstract
Background: Resistance genes transferred by plasmids are important factors that can contribute to the occurrence of quinolone resistance, specifically in Escherichia coli strains. Methods: A total number of 117 diarrhoeagenic E. coli strains were tested for the resistance to nalidixic acid, ofloxacin, ciprofloxacin and levofloxacin and for the presence of qnrA, qnrB and qnrS genes determinants by polymerase chain reaction. Antibiotic susceptibility test was performed using the Clinical and Laboratory Standard Institute standard method. Results: The highest resistance belonged to the nalidixic acid (52.14%) and the least resistance to levofloxacin (37.61%). In this study, among a total of 117 samples, 23 (19.66%) strains were susceptible to all the studied antibiotics. Among the remainder, 94 (80.34%) samples resistant to at least one quinolone, three genes including qnrA, qnrB and qnrS were present in 19.15%, 88.30% and 78.72% isolates, respectively. Furthermore, 51.06% of strains had A−, B+ and S+ pattern that seems to have a significant association (P Conclusions: The results of present study show the presence of a high frequency of qnr genes in E. coli strains resistant to quinolones in clinical samples from southwest of Iran. In addition, this study approved that plasmid-mediated quinolone resistance is a possible mechanism among the quinolones-resistant E. coli isolated from patients with diarrhoea in the study, and also qnrB and qnrS genes seem to be more important in resistance to quinolones.
- Published
- 2016
16. Magneto-optic studies of magnetic oxides
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Gillian A. Gehring, David S. Score, A. Mark Fox, Abbas Mokhtari, Marzook S. Alshammari, and J. R. Neal
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Materials science ,Condensed matter physics ,Magnetic circular dichroism ,chemistry.chemical_element ,Substrate (electronics) ,Condensed Matter Physics ,Manganite ,Spectral line ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,chemistry ,Thin film ,Cobalt ,Magneto ,Magnetite - Abstract
A brief review of the use of magneto-optic methods to study magnetic oxides is given. A simple method to obtain the magnetic circular dichroism (MCD) of a thin film on a transparent substrate is described. The method takes full account of multiple reflections in the film and substrate. Examples of the magneto-optic spectra of Co-doped ZnO, Fe 3 O 4 , and GdMnO 3 are given. The Maxwell–Garnett method is used to describe the effects of metallic cobalt inclusions in Co:ZnO samples, and the change of the MCD spectra of Fe 3 O 4 at the Verwey temperature is discussed. Data showing different MCD signals at different energies is presented for GdMnO 3 .
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- 2012
17. Magneto-optical study of the Verwey transition in magnetite
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Harry J. Blythe, Gillian A. Gehring, Mahrous R. Ahmed, A. M. Fox, Abbas Mokhtari, A.J. Behan, and J. R. Neal
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Charge ordering ,Materials science ,Condensed matter physics ,Oscillator strength ,Diagonal ,Physics::Optics ,Dielectric ,Thin film ,Atmospheric temperature range ,Anomaly (physics) ,Condensed Matter Physics ,Spectral line ,Electronic, Optical and Magnetic Materials - Abstract
We have made the first detailed Faraday measurements on thin films of Fe3O4 for 10
- Published
- 2007
18. Magneto-optical and transport studies of ZnO-based dilute magnetic semiconductors
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Michael Ziese, A. M. Fox, Abbas Mokhtari, A.J. Behan, Gillian A. Gehring, Harry J. Blythe, J. R. Neal, and R. M. Ibrahim
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Materials science ,Condensed matter physics ,Magnetic circular dichroism ,Magnetometer ,Magnetic semiconductor ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Pulsed laser deposition ,law.invention ,Condensed Matter::Materials Science ,symbols.namesake ,Magnetization ,Hall effect ,law ,Condensed Matter::Superconductivity ,Faraday effect ,symbols ,Thin film - Abstract
Thin film samples of ZnO doped with V were grown on sapphire substrates by pulsed laser deposition (PLD). The magnetization was measured by SQUID magnetometry and the films were found to be ferromagnetic at room temperature. The transmission, Faraday rotation and magnetic circular dichroism were measured as a function of frequency at room temperature over an energy range of 1.5–4.0 eV and carrier concentrations were determined from Hall effect measurements. Clear magneto-optical signals that are ferromagnetic in origin were observed at the ZnO band edge and the optimal conditions for observing large ferromagnetic magneto-optic signals are discussed.
- Published
- 2007
19. ChemInform Abstract: Magneto-optic Studies of Magnetic Oxides
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A. Mark Fox, J. R. Neal, Gillian A. Gehring, Abbas Mokhtari, Marzook S. Alshammari, and David S. Score
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Condensed matter physics ,Magnetic circular dichroism ,Chemistry ,chemistry.chemical_element ,General Medicine ,Substrate (electronics) ,Spectral line ,Metal ,Condensed Matter::Materials Science ,Chemical physics ,visual_art ,visual_art.visual_art_medium ,Thin film ,Magneto ,Cobalt - Abstract
A brief review of the use of magneto-optic methods to study magnetic oxides is given. A simple method to obtain the magnetic circular dichroism (MCD) of a thin film on a transparent substrate is described. The method takes full account of multiple reflections in the film and substrate. Examples of the magneto-optic spectra of Co-doped ZnO, Fe 3 O 4 , and GdMnO 3 are given. The Maxwell–Garnett method is used to describe the effects of metallic cobalt inclusions in Co:ZnO samples, and the change of the MCD spectra of Fe 3 O 4 at the Verwey temperature is discussed. Data showing different MCD signals at different energies is presented for GdMnO 3 .
- Published
- 2012
20. Ultra-fast spectroscopy investigation of Verwey transition in magnetite
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J. R. Neal, Gillian A. Gehring, Harry J. Blythe, and Abbas Mokhtari
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chemistry.chemical_compound ,Charge ordering ,Materials science ,Condensed matter physics ,chemistry ,General Physics and Astronomy ,Ultra fast ,Spectroscopy ,Magnetite - Published
- 2015
21. Magnetoresistance of magnetically doped ZnO films
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Abbas Mokhtari, A.J. Behan, Michael Ziese, Gillian A. Gehring, A. M. Fox, and Harry J. Blythe
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Colossal magnetoresistance ,Materials science ,Magnetic moment ,Ferromagnetism ,Condensed matter physics ,Magnetoresistance ,Doping ,General Materials Science ,Thin film ,Condensed Matter Physics ,human activities ,Magnetic field ,Pulsed laser deposition - Abstract
Magnetoresistance measurements have been made at 5 K on doped ZnO thin films grown by pulsed laser deposition. ZnCoO, ZnCoAlO and ZnMnAlO samples have been investigated and compared to similar films containing no transition metal dopants. It is found that the Co-doped samples with a high carrier concentration have a small negative magnetoresistance, irrespective of their magnetic moment. On decreasing the carrier concentration, a positive contribution to the magnetoresistance appears and a further negative contribution. This second, negative contribution, which occurs at very low carrier densities, correlates with the onset of ferromagnetism due to bound magnetic polarons suggesting that the negative magnetoresistance results from the destruction of polarons by a magnetic field. An investigation of the anisotropic magnetoresistance showed that the orientation of the applied magnetic field, relative to the sample, had a large effect. The results for the ZnMnAlO samples showed less consistent trends.
- Published
- 2011
22. On Using Magnetic and optical methods to determine the size and characteristics of nanoparticles embedded in oxide semiconductors
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Harry J. Blythe, Gillian A. Gehring, Qi Feng, Mohammed S Al Qahtani, A. Mark Fox, Abbas Mokhtari, David S. Score, and Marzook S. Alshammari
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Condensed Matter - Materials Science ,Materials science ,Doping ,Analytical chemistry ,Nanoparticle ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,equipment and supplies ,Electronic, Optical and Magnetic Materials ,Paramagnetism ,Condensed Matter::Materials Science ,Oxide semiconductor ,Transition metal ,Condensed Matter::Strongly Correlated Electrons ,Electrical and Electronic Engineering ,human activities - Abstract
Films of oxides doped with transition metals are frequently believed to have magnetic inclusions. Magnetic methods to determine the amount of nanophases and their magnetic characteristics are described. The amount of the sample that is paramagnetic may also be measured. Optical methods are described and shown to be very powerful to determine which defects are also magnetic., Comment: Manuscript of poster to be presented at MMM-Intermag 2010. Accepted for publication in Magnetic Trans of IEEE
- Published
- 2010
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23. X-ray absorption fine structure and magnetization characterization of the metallic Co component in Co-doped ZnO thin films
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Timothy C. Droubay, J. R. Neal, Vaithiyalingam Shutthanandan, Harry J. Blythe, Tiffany C. Kaspar, Mark Fox, Abbas Mokhtari, Steve M. Heald, A.J. Behan, Scott A. Chambers, and Gillian A. Gehring
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Materials science ,Magnetism ,Analytical chemistry ,Intermetallic ,Magnetic semiconductor ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Pulsed laser deposition ,X-ray absorption fine structure ,Condensed Matter::Materials Science ,Magnetization ,Nuclear magnetic resonance ,Thin film ,Superparamagnetism - Abstract
X-ray absorption fine-structure (XAFS) measurements have been used to characterize a series of Co-doped ZnO films grown on sapphire substrates by pulsed laser deposition. The emphasis is on characterization of the fate of the Co dopant: metallic particles or substitutional $\text{Co}2+$. It is shown that analysis of both the near edge and extended fine structure can provide a measurement of the fraction of metallic Co. Any quantitative understanding of magnetism in this system needs to take into account both types of Co. Results are reported for two types of films from two different groups that show distinctly different behaviors. Films grown with high concentrations of Co show varying amounts of metallic Co that could be identified as a close-packed form of Co. Another set of films was annealed in Zn vapor to induce magnetism. These films also showed significant metallic Co, but of a different type similar to the CoZn intermetallic. The bulk forms of both metals are magnetic and should contribute to the magnetism. However, the measured room-temperature magnetic moments for some films are inconsistent with the expected moments based on the bulk magnetic values for either Co metal or CoZn. The magnetic properties of the small metal particles are likely changed by their surroundings. Low-temperature magnetic measurements for one of the samples confirmed this with an estimated blocking temperature of 50 K.
- Published
- 2009
24. Two magnetic regimes in doped ZnO corresponding to a dilute magnetic semiconductor and a dilute magnetic insulator
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J. R. Neal, A.J. Behan, David S. Score, Harry J. Blythe, Gillian A. Gehring, A. M. Fox, Xiao-Hong Xu, and Abbas Mokhtari
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Condensed Matter - Materials Science ,Materials science ,Spins ,Condensed matter physics ,Strongly Correlated Electrons (cond-mat.str-el) ,Magnetism ,Doping ,General Physics and Astronomy ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Magnetic semiconductor ,Variable-range hopping ,Degenerate semiconductor ,Ion ,Condensed Matter - Strongly Correlated Electrons ,Condensed Matter::Materials Science ,Ferromagnetism ,Condensed Matter::Strongly Correlated Electrons - Abstract
Films of ZnO doped with magnetic ions, Mn and Co and, in some cases, with Al have been fabricated with a very wide range of carrier densities. Ferromagnetic behaviour is observed in both insulating and metallic films, but not when the carrier density is intermediate. Insulating films exhibit variable range hopping at low temperatures and are ferromagnetic at room temperature due to the interaction of the localised spins with static localised states. The magnetism is quenched when carriers in the localised states become mobile. In the metallic (degenerate semiconductor) range, robust ferromagnetism reappears together with very strong magneto-optic signals and room temperature anomalous Hall data. This demonstrates the polarisation of the conduction bands and indicates that, when ZnO is doped into the metallic regime, it behaves as a genuine magnetic semiconductor., Comment: The manuscript has been improved following suggestions from the referees and is now in press with Phys Rev Lett
- Published
- 2007
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25. Carrier-induced ferromagnetism in n-type ZnMnAlO and ZnCoAlO thin films at room temperature
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A. M. Fox, Abbas Mokhtari, Harry J. Blythe, Xiao-Hong Xu, Neal, Gillian A. Gehring, Ibrahim, A.J. Behan, and Michael Ziese
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Condensed Matter - Materials Science ,Materials science ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed matter physics ,Spintronics ,business.industry ,Transition temperature ,Doping ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Physics and Astronomy ,Magnetic semiconductor ,Condensed Matter - Strongly Correlated Electrons ,Condensed Matter::Materials Science ,Magnetization ,Semiconductor ,Transition metal ,Ferromagnetism ,Condensed Matter::Superconductivity ,Condensed Matter::Strongly Correlated Electrons ,business - Abstract
The realization of semiconductors that are ferromagnetic above room temperature will potentially lead to a new generation of spintronic devices with revolutionary electrical and optical properties. Transition temperatures in doped ZnO are high but, particularly for Mn doping, the reported moments have been small. We show that by careful control of both oxygen deficiency and aluminium doping the ferromagnetic moments measured at room temperature in n-type ZnMnO and ZnCoO are close to the ideal values of 5mB and 3mB respectively. Furthermore a clear correlation between the magnetisation per transition metal ion and the ratio of the number of carriers to the number of transition metal donors was established as is expected for carrier induced ferromagnetism for both the Mn and Co doped films. The dependence of the magnetisation on carrier density is similar to that predicted for the transition temperature for a dilute magnetic semiconductor in which the exchange between the transition metal ions is through the free carriers., 14 pages pdf
- Published
- 2006
26. Development of Multiplex PCR for Rapid and Sensitive Detection of Human Papillomaviruses in Cervical Cancer
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Abolfazl Movafagh, Fateme Zandnia, Mohammad Taghi Kardi, Abbas Mokhtari-Farsani, and Abbas Doosti
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Cervical cancer ,Hpv types ,business.industry ,HPV Positive ,virus diseases ,General Medicine ,medicine.disease ,Virology ,female genital diseases and pregnancy complications ,genomic DNA ,Multiplex polymerase chain reaction ,Biomarker (medicine) ,Medicine ,Human papillomavirus ,business - Abstract
OBJECTIVES Reffering to an increase in cervical cancer in the recent years, rapid, sensitive and economical detection of human papillomaviruses (HPVs) as causative agents of cervical cancer is important. The traditional methods for the detection of HPVs in cervical cancer, such as pap smear, suffer from limitation and PCR has a potential to overcome the limitaitons. The purpose of present research work was to identify the five important strains of HPV (16, 18, 31, 33 and 45) simultaneously by Multiplex PCR application. METHODS Study was done on 100 cervical lesions of women. DNA was extracted from specimens by a genomic DNA purification kit. A 5-plex PCR was developed for the simultaneous detection of major HPV. Five pair of new primers was designed for detection of HPV 16, 18, 31, 33 and 45 by Multiplex PCR. RESULTS Among the 100 evaluated samples, 82 were found positive to HPVs. In the meantime the highest rate of infection was for HPV 16. Also 30 of HPV positive samples had infections with two or more HPV types. CONCLUSION Multiplex PCR assay used in present study can provide a rapid, sensitive and economical method for detection of viral infections and is applicable to small volumes of vaginal samples.
- Published
- 1969
27. Study of the frequency of Clostridium difficile tcdA, tcdB, cdtA and cdtB genes in feces of Calves in south west of Iran
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Abbas Doosti and Abbas Mokhtari-Farsani
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DNA, Bacterial ,Microbiology (medical) ,Bacterial Toxins ,Clostridium difficile toxin A ,Virulence ,Toxin B ,Clostridium difficile toxin B ,Toxin A ,Drug resistance ,Enterotoxin ,Calves ,Microbial Sensitivity Tests ,Biology ,Iran ,Polymerase Chain Reaction ,Microbiology ,Enterotoxins ,Feces ,Bacterial Proteins ,Drug Resistance, Bacterial ,medicine ,Animals ,Pathogen ,ADP Ribose Transferases ,Clostridioides difficile ,Research ,Clindamycin ,General Medicine ,Clostridium difficile ,Virology ,Anti-Bacterial Agents ,Cross-Sectional Studies ,Infectious Diseases ,Clostridium Infections ,Cattle ,medicine.drug ,Binary toxin - Abstract
Background Clostridium difficile (C. difficile) is a gram-positive, toxin-producing bacillus which is an intestinal pathogen in both humans and animals and causes a range of digestive disorders including inflammation of the bowel, abdominal pain, fever and diarrhea. C. difficile toxins include enterotoxin (Toxin A), cytotoxin (Toxin B) and a binary toxin. Two large protein toxins A and B are encoded by separate genes, tcdA and tcdB. Clostridium difficile infection (CDI) mainly caused by the activity of the genes tcdA and tcdB. The binary toxin is encoded by the genes cdtA and cdtB. The binary toxin caused increased adherence of bacteria to intestinal epithelium. The aim of the present study was isolation of C. difficile from feces of calves, and study of the frequency of C. difficile virulence genes. Methods 150 samples of fresh feces from calves were collected and C. difficile was isolated from feces of calves using bacterial culture methods. DNA was extracted by a genomic DNA purification kit. Then PCR method was used for definitive diagnosis of C. difficile. Multiplex PCR method performed for identification of tcdA, tcdB, cdtA and cdtB genes. In the final stage antimicrobial resistance determining was carried out by standard Bauer-Kirby disk diffusion method. Results C. difficile was isolated from 90 samples (60%). The tcdA was observed in 8 isolates (8.8%), tcdB in 16 isolates (17.7%), cdtA in 8 isolates (8.8%) and cdtB in 14 isolates (15.5%). Only 1 isolated (1.1%) was containing all four genes tcdA, tcdB, cdtA and cdtB, 2 isolates (2.2%) only had both tcdA and tcdB genes, and there was no sample positive only for both cdtA and cdtB. The highest rate of drug resistance was against clindamycin (100%) and the highest rate of drug sensitivity was against ciprofloxacin (50%). Conclusion The results showed high incidence of C. difficile and also high antibiotic resistance of this bacterium, but frequency of strains containing virulence genes (tcdA, tcdB, cdtA and cdtB) was low.
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28. Application of multiplex PCR for Rapid and sensitive detection of human papillomaviruses in cervical cancer.
- Author
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Zandnia F, Doosti A, Mokhtari-Farsani A, Kardi MT, and Movafagh A
- Abstract
Objectives: Reffering to an increase in cervical cancer in the recent years, rapid, sensitive and economical detection of human papillomaviruses (HPVs) as causative agents of cervical cancer is important. The traditional methods for the detection of HPVs in cervical cancer, such as pap smear, suffer from limitation and PCR has a potential to overcome the limitaitons. The purpose of present research work was to identify the five important strains of HPV (16, 18, 31, 33 and 45) simultaneously by Multiplex PCR application., Methods: Study was done on 100 cervical lesions of women. DNA was extracted from specimens by a genomic DNA purification kit. A 5-plex PCR was developed for the simultaneous detection of major HPV. Five pair of new primers was designed for detection of HPV 16, 18, 31, 33 and 45 by Multiplex PCR., Results: Among the 100 evaluated samples, 82 were found positive to HPVs. In the meantime the highest rate of infection was for HPV 16. Also 30 of HPV positive samples had infections with two or more HPV types., Conclusion: Multiplex PCR assay used in present study can provide a rapid, sensitive and economical method for detection of viral infections and is applicable to small volumes of vaginal samples.
- Published
- 2016
- Full Text
- View/download PDF
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