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Papers by babak shahbazi

Journal of Reports in Pharmaceutical Sciences

A lot of chemicals such as poly (amidoamine) ( PAMAM - NH2 ) dendrimers have pharmaceutical appli... more A lot of chemicals such as poly (amidoamine) ( PAMAM - NH2 ) dendrimers have pharmaceutical applications, but the major problem with PAMAM - NH2 is their cytotoxicity and mutagenicity. In this research, we have investigated the cytotoxicity and mutagenicity of various generations of PAMAM-NH2 (G2.0, G3.0, G4.0, and G5.0). The cytotoxicity of PAMAM-NH2 at the dilutions of 0.01, 0.001 and 0.0001(W/W) to human mesenchymal stem cells (MSCs) and human gastric adenocarcinoma (AGS) cells was determined using the standard methyl-thiazol - tetrazolium ( MTT ) assay. To determine mean lethal dose (LD 50 ) of PAMAM-NH2 at doses of 30, 47, 73.5, 115 and 180 mg/kg, 125 Bagg albino/c (BALB/c) mice (8–10 weeks of age, weighing approximately 20 g) were used and also, for determining the mutagenicity effect of PAMAM-NH2, 50μL volume of this substance in the Ame’s test with S. typhimurium was applied. In the MTT assay the most toxic effects, on both of the cell lines, were related to the time when G2.0, G3.0, G4.0 and G5.0 were applied at different dilution of 0.01, 0.001, 0.0001(W/W), respectively. LD50 was determined 73.5 mg/kg. Also in the Ame’s test, the number of reverted colonies was increased by applying higher generations and inhibition percentages of PAMAM - NH2 that were 69.47%, 68.42%, 64.210% and 64.21% for G2.0, G3.0, G4.0 and G5.0, respectively. According to these results, PAMAM - NH2 generations had cytotoxicity effects on MSCs and AGS cells ; also toxicity and mutagenicity of the substance were proved in mice and S. typhimurium , respectively. So in order to use PAMAM - NH2 in pharmaceuticals, it must be subjected to various tests to ensure its safety.

Jundishapur Journal of Microbiology, May 31, 2015

Background: Vibrio cholerae causes diarrhoeal disease that afflicts thousands of people annually.... more Background: Vibrio cholerae causes diarrhoeal disease that afflicts thousands of people annually. V. cholerae is classified on the basis of somatic antigens into serovars or serogroups and there are at least 200 known serogroup. Two serogroups, O1 and O139 have been associated with epidemic diseases. Virulence genes of these bacteria are OmpW, ctxA and tcpA. Objectives: Due to the importance of V. cholerae infection and developing molecular diagnostics of this organism in medical and microbiology sciences, this study aimed to describe molecular characterization of V. cholerae isolated from clinical samples using a molecular method. Materials and Methods: In this study, 48 samples were provided during summer 2013 (late August and early September) by reference laboratory. Samples were assessed using biochemical tests initially. The primer of OmpW, ctxA and tcpA genes was used in Polymerase Chain Reaction (PCR) protocols. Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR and Repetitive Extragenic Palindromic (REP)-PCR methods were used to subtype V. cholerae. Results: In this study, from a total of 48 clinical stool samples 39 (81.2 %) were positive for V. cholerae in biochemical tests and bacteria culture tests. The PCR results showed that of 39 positive isolates 35 (89.7%), 34 (87.1%) and 37 (94.8%) were positive for ctxA, tcpA and OmpW gene, respectively. Also, in the REP-PCR method with ERIC primer strains were divided into 10 groups. In the REP-PCR method with REP primer, strains were divided into 13 groups. Conclusions: Polymerase chain reaction has specificity and accuracy for identification of the organism and is able to differentiate biotypes. Enterobacterial repetitive intergenic consensus sequence is one of the informative and discriminative methods for the analysis of V. cholerae diversity. The REP-PCR is a less informative and discriminative method compared to other methods for the analysis of V. cholerae diversity.

TEST Engineering & Management, Mar 12, 2020

The sand accumulates at the well leads to increase in sand production resulting in lost productio... more The sand accumulates at the well leads to increase in sand production resulting in lost production and increased well maintenance cost. The main objective of this research is to evaluate sand produced from the field and to propose a suitable prevention sand method.Four samples of sand with different mass size are prepared for the test and then placed in a sieve shaker with openings in the decreasing order of sieve size. Sieves of sizes 2000, 1000, 500, 250, 125, 36 microns and a no sieve pan were used to sample the sand. Granular particles are accumulated on different sieves, which give the particle size distribution of the samples.From sieving analysis, the results showed that for well one the majority of the sand material is retained on the 500-size sieve. While, for the second sample the results showed that the percentage of sand accumulated on the 125 micron is the highest, which indicates that the sample consists of fine particles. Further, the highest percent weight retained of this sample is reported at mesh size of 125 micron. Further, the sieve analysis for the rest of samples indicated that maximum of the particles of the sand sample belong to the large category of particle size classification.This can be justified as the highest percent weight retained of both samples are reported at the larger micron size mesh particularly at 2000 and 1000 micron mesh sizes. Based on tiffin Criteria, the results elaborated that well one can use standalone screen or wire-wrapped screen and for the well two must use mesh screen. While for well three and well four, it is suggested to use gravel pack that can utilize slotted liner since these types of sand are non-uniform sand.

Journal of the Medical Sciences, Sep 15, 2014

Iranian Journal of Public Health, 2014

Background: Cyanobacteria as photosynthetic organisms have a main effect on life and productivity... more Background: Cyanobacteria as photosynthetic organisms have a main effect on life and productivity of the aquatic ecosystems. The long-term studies on the identification, distribution and diversity of Cyanobacteria is crucial in the Caspian Sea. Methods: Four transects were determined parallel to the Sabzehrud River, the Lavij River, Noor River, and the Department of Marine Biology of Tarbiat Modares University from 2014 to 2015. Samples were seasonally collected from three stations in each transect by a plankton net with a mesh size of 55 and the Ruthner's bathometer. Standard hydrobiological and phycology approaches were used for identification and totaling abundance of cyanobacteria. Results: The most number of cyanobacteria was observed in station A1 with number of 1062500 N/L during summer season. Genera Chroococcus, Gloeocapsa, Merismopedia, Microcystis belong to unicellular taxa and Anabaena, Anabaenopsis, Nostoc, Oscillatoria, Phormidium were identified as the multicellular genera. Anabaenopsis nadsonii was observed as the most distributed species. Conclusion: The result showed that cyanobacteria abundance was significantly different among stations and all seasons. The reported blue-green algae also have no same frequency among stations inside each transect (Test Chi-Square, P <0.05).

DOI: 10.7508/rmm.2015.03.008 Abstract Background: Methicillin resistant Staphylococcus aureus (MR... more DOI: 10.7508/rmm.2015.03.008 Abstract Background: Methicillin resistant Staphylococcus aureus (MRSA) is one of the major agents for increasing number of serious hospital and community acquired infections. The aim of this study was to investigate the occurrence of the MRSA and mecA gene among nosocomial and environmental specimens in Kurdistan hospitals and determining the antibiotic resistance of the isolates. Materials and Methods: A total of 264 clinical and environmental Staphylococcus was isolated from Kurdistan medical University Hospitals, in February 2011 to June 2012 Iran, and their susceptibility patterns to different antibiotics were determined. Furthermore, agar screen method was used to determine oxacillin resistant isolates. Finally, using PCR, the oxacillin resistant isolates were tested for the presence of mecA gene. Results: In this study, from 88 (93.18%) Staphylococcus aureus isolates, 82 were found resistant to oxacillin using agar screen method and mecA gene was ...

Iranian Journal of Public Health, 2014

Iranian Journal of Public Health, 2014

Research in Molecular Medicine, 2015

Background: Methicillin resistant Staphylococcus aureus (MRSA) is one of the major agents for inc... more Background: Methicillin resistant Staphylococcus aureus (MRSA) is one of the major agents for increasing number of serious hospital and community acquired infections. The aim of this study was to investigate the occurrence of the MRSA and mecA gene among nosocomial and environmental specimens in Kurdistan hospitals and determining the antibiotic resistance of the isolates. Materials and Methods: A total of 264 clinical and environmental Staphylococcus was isolated from Kurdistan medical University Hospitals, in February 2011 to June 2012 Iran, and their susceptibility patterns to different antibiotics were determined. Furthermore, agar screen method was used to determine oxacillin resistant isolates. Finally, using PCR, the oxacillin resistant isolates were tested for the presence of mecA gene. Results: In this study, from 88 (93.18%) Staphylococcus aureus isolates, 82 were found resistant to oxacillin using agar screen method and mecA gene was detected in 66 strains (75%). Our results showed that the agar screen method is more reliable in determination of MRSA strains compared to PCR. Conclusion: In this research the studied MRSA were found with high prevalence and mecA was widespread in S. aureus isolates in Sanandaj.

Iranian Journal of Public Health, 2014

The sand accumulates at the well leads to increase in sand production resulting in lost productio... more The sand accumulates at the well leads to increase in sand production resulting in lost production and increased well maintenance cost. The main objective of this research is to evaluate sand produced from the field and to propose a suitable prevention sand method.Four samples of sand with different mass size are prepared for the test and then placed in a sieve shaker with openings in the decreasing order of sieve size. Sieves of sizes 2000, 1000, 500, 250, 125, 36 microns and a no sieve pan were used to sample the sand. Granular particles are accumulated on different sieves, which give the particle size distribution of the samples.From sieving analysis, the results showed that for well one the majority of the sand material is retained on the 500-size sieve. While, for the second sample the results showed that the percentage of sand accumulated on the 125 micron is the highest, which indicates that the sample consists of fine particles. Further, the highest percent weight retained o...

Iranian Journal of Public Health, 2014

Journal of the Medical Sciences, 2014

Advanced Biomedical Research, 2017

Background: Staphylococcus aureus strains that are Panton-Valentine leukocidin (PVL) positive cau... more Background: Staphylococcus aureus strains that are Panton-Valentine leukocidin (PVL) positive cause severe skin and soft tissue infections as well as necrotizing pneumonia. The presence of PVL gene is a marker for methicillin-resistant S. aureus; therefore, survey on prevalence and phylogenetic distribution of PVL is of great importance for public health. The aim of this research was molecular epidemiology survey of S. aureus PVL positive, isolated from two tertiary hospitals of Sanandaj. Materials and Methods: A total of 264 staphylococci isolates were collected from clinical specimens, hospital personnel and hospital environment of two tertiary hospitals of Sanandaj, in 2012 (Toohid and Besat). Bacterial cultures and biochemical tests were performed for S. aureus detection. Then, polymerase chain reaction (PCR) and repetitive sequence-based PCR (rep-PCR) were used for the determination of prevalence and molecular epidemiology of S. aureus PVL, respectively. Data were analyzed using the Fisher's exact test (P < 0.05). Results: From 264 staphylococci isolates, 88 (33.33%) were detected as S. aureus. Furthermore, 20 out of 88 (22.72%) strains of S. aureus were PVL positive according to PCR results. Rep-PCR showed six main clusters of S. aureus samples. PVL had similar clonality between different samples. No signifi cant relationship was observed between PVL positive S. aureus and rep-PCR patterns (P = 0.98). Conclusion: These results showed that a clone of S. aureus PVL positive has spread between the community and hospital settings. Therefore, appropriate measures are required to prevent the spread of staphylococci and other bacteria in hospitals.

International Journal of Enteric Pathogens, 2014

Background: Nano composites are widely used in medical sciences recently. Identification of chemi... more Background: Nano composites are widely used in medical sciences recently. Identification of chemical mutagens is an important issue in drug safety. Objectives: The aim of this study was to investigate mutagenicity and antibacterial activity of various generations of poly (amid amine) (PAMAM) dendrimers and agonic acid poly (amid amine) (PAMAM) Nano composite G2 on enteric pathogenic bacteria. Materials and Methods: Disc diffusion method, MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) determination were performed for antibacterial activity survey. Mutagenic properties were determined by Ames assay. Results: Various dilutions of PAMAM generations (G2, G3, G4 and G5) and agonic acid PAMAM Nano composite G2 had antibacterial effect on Escherichia coli, Salmonella enterica, Salmonella typhimurium, Enterococcus faecalis and Staphylococcus aureus. In Ames assay, reverted colonies were increased by PAMAM generations increasing. Moreover, reverted colonies Ames assay were lower when Nano composite G2 was applied. Conclusions: PAMAM generations and agonic acid PAMAM Nano composite G2 contain compounds with therapeutic potential and antibacterial characteristics, which can be used in medicine. Because some chemicals have mutagenic and carcinogenic properties, identification of these chemical is of great importance.

International Journal of Steel Structures, 2021

In this study, a new hybrid energy dissipation device is developed by combining two friction damp... more In this study, a new hybrid energy dissipation device is developed by combining two friction dampers (auxiliary and main fuse) in series to be used for the seismic control of two different earthquake intensities. Compared with the conventional friction dampers, the new hybrid damper has an advantage in that only the auxiliary fuse (with low sliding force) is activated for moderate earthquakes and both fuses work simultaneously for strong earthquakes. Cyclic loading tests of the combined hybrid dampers are carried out to evaluate their seismic energy dissipation capability. The obtained experimental force displacement indicates proper details of the new damper to create two performance levels. Finite element analyses of the test specimens are also carried out for comparison and have good agreement with the test results. Force–displacement characteristics, energy dissipation, and equivalent viscous damping are also derived and good agreement has been found. Moreover, it is demonstrated that by engaging the main fuse with non-loaded pretension bolts, the strength losses of the hybrid damper in the subsequent cycles are limited compared with the common friction dampers, which can be called the “resurrection-type” behavior of the main fuse in the main shocks. To evaluate the effects of the proposed damper, typical 3- and 9-story steel buildings are modeled and their seismic responses under 22 earthquake excitations are investigated using incremental dynamic nonlinear time-history. Comparison of incremental dynamic analysis (IDA) curves and their medians revealed that using a hybrid friction damper (HFD) reduces the probability of reaching all the defined damage states. Moreover, the reduction effect of HFD was recognizable in 9-story frames.

Journal of Reports in Pharmaceutical Sciences

A lot of chemicals such as poly (amidoamine) ( PAMAM - NH2 ) dendrimers have pharmaceutical appli... more A lot of chemicals such as poly (amidoamine) ( PAMAM - NH2 ) dendrimers have pharmaceutical applications, but the major problem with PAMAM - NH2 is their cytotoxicity and mutagenicity. In this research, we have investigated the cytotoxicity and mutagenicity of various generations of PAMAM-NH2 (G2.0, G3.0, G4.0, and G5.0). The cytotoxicity of PAMAM-NH2 at the dilutions of 0.01, 0.001 and 0.0001(W/W) to human mesenchymal stem cells (MSCs) and human gastric adenocarcinoma (AGS) cells was determined using the standard methyl-thiazol - tetrazolium ( MTT ) assay. To determine mean lethal dose (LD 50 ) of PAMAM-NH2 at doses of 30, 47, 73.5, 115 and 180 mg/kg, 125 Bagg albino/c (BALB/c) mice (8–10 weeks of age, weighing approximately 20 g) were used and also, for determining the mutagenicity effect of PAMAM-NH2, 50μL volume of this substance in the Ame’s test with S. typhimurium was applied. In the MTT assay the most toxic effects, on both of the cell lines, were related to the time when G2.0, G3.0, G4.0 and G5.0 were applied at different dilution of 0.01, 0.001, 0.0001(W/W), respectively. LD50 was determined 73.5 mg/kg. Also in the Ame’s test, the number of reverted colonies was increased by applying higher generations and inhibition percentages of PAMAM - NH2 that were 69.47%, 68.42%, 64.210% and 64.21% for G2.0, G3.0, G4.0 and G5.0, respectively. According to these results, PAMAM - NH2 generations had cytotoxicity effects on MSCs and AGS cells ; also toxicity and mutagenicity of the substance were proved in mice and S. typhimurium , respectively. So in order to use PAMAM - NH2 in pharmaceuticals, it must be subjected to various tests to ensure its safety.

Jundishapur Journal of Microbiology, May 31, 2015

Background: Vibrio cholerae causes diarrhoeal disease that afflicts thousands of people annually.... more Background: Vibrio cholerae causes diarrhoeal disease that afflicts thousands of people annually. V. cholerae is classified on the basis of somatic antigens into serovars or serogroups and there are at least 200 known serogroup. Two serogroups, O1 and O139 have been associated with epidemic diseases. Virulence genes of these bacteria are OmpW, ctxA and tcpA. Objectives: Due to the importance of V. cholerae infection and developing molecular diagnostics of this organism in medical and microbiology sciences, this study aimed to describe molecular characterization of V. cholerae isolated from clinical samples using a molecular method. Materials and Methods: In this study, 48 samples were provided during summer 2013 (late August and early September) by reference laboratory. Samples were assessed using biochemical tests initially. The primer of OmpW, ctxA and tcpA genes was used in Polymerase Chain Reaction (PCR) protocols. Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR and Repetitive Extragenic Palindromic (REP)-PCR methods were used to subtype V. cholerae. Results: In this study, from a total of 48 clinical stool samples 39 (81.2 %) were positive for V. cholerae in biochemical tests and bacteria culture tests. The PCR results showed that of 39 positive isolates 35 (89.7%), 34 (87.1%) and 37 (94.8%) were positive for ctxA, tcpA and OmpW gene, respectively. Also, in the REP-PCR method with ERIC primer strains were divided into 10 groups. In the REP-PCR method with REP primer, strains were divided into 13 groups. Conclusions: Polymerase chain reaction has specificity and accuracy for identification of the organism and is able to differentiate biotypes. Enterobacterial repetitive intergenic consensus sequence is one of the informative and discriminative methods for the analysis of V. cholerae diversity. The REP-PCR is a less informative and discriminative method compared to other methods for the analysis of V. cholerae diversity.

TEST Engineering & Management, Mar 12, 2020

The sand accumulates at the well leads to increase in sand production resulting in lost productio... more The sand accumulates at the well leads to increase in sand production resulting in lost production and increased well maintenance cost. The main objective of this research is to evaluate sand produced from the field and to propose a suitable prevention sand method.Four samples of sand with different mass size are prepared for the test and then placed in a sieve shaker with openings in the decreasing order of sieve size. Sieves of sizes 2000, 1000, 500, 250, 125, 36 microns and a no sieve pan were used to sample the sand. Granular particles are accumulated on different sieves, which give the particle size distribution of the samples.From sieving analysis, the results showed that for well one the majority of the sand material is retained on the 500-size sieve. While, for the second sample the results showed that the percentage of sand accumulated on the 125 micron is the highest, which indicates that the sample consists of fine particles. Further, the highest percent weight retained of this sample is reported at mesh size of 125 micron. Further, the sieve analysis for the rest of samples indicated that maximum of the particles of the sand sample belong to the large category of particle size classification.This can be justified as the highest percent weight retained of both samples are reported at the larger micron size mesh particularly at 2000 and 1000 micron mesh sizes. Based on tiffin Criteria, the results elaborated that well one can use standalone screen or wire-wrapped screen and for the well two must use mesh screen. While for well three and well four, it is suggested to use gravel pack that can utilize slotted liner since these types of sand are non-uniform sand.

Journal of the Medical Sciences, Sep 15, 2014

Iranian Journal of Public Health, 2014

Background: Cyanobacteria as photosynthetic organisms have a main effect on life and productivity... more Background: Cyanobacteria as photosynthetic organisms have a main effect on life and productivity of the aquatic ecosystems. The long-term studies on the identification, distribution and diversity of Cyanobacteria is crucial in the Caspian Sea. Methods: Four transects were determined parallel to the Sabzehrud River, the Lavij River, Noor River, and the Department of Marine Biology of Tarbiat Modares University from 2014 to 2015. Samples were seasonally collected from three stations in each transect by a plankton net with a mesh size of 55 and the Ruthner's bathometer. Standard hydrobiological and phycology approaches were used for identification and totaling abundance of cyanobacteria. Results: The most number of cyanobacteria was observed in station A1 with number of 1062500 N/L during summer season. Genera Chroococcus, Gloeocapsa, Merismopedia, Microcystis belong to unicellular taxa and Anabaena, Anabaenopsis, Nostoc, Oscillatoria, Phormidium were identified as the multicellular genera. Anabaenopsis nadsonii was observed as the most distributed species. Conclusion: The result showed that cyanobacteria abundance was significantly different among stations and all seasons. The reported blue-green algae also have no same frequency among stations inside each transect (Test Chi-Square, P <0.05).

DOI: 10.7508/rmm.2015.03.008 Abstract Background: Methicillin resistant Staphylococcus aureus (MR... more DOI: 10.7508/rmm.2015.03.008 Abstract Background: Methicillin resistant Staphylococcus aureus (MRSA) is one of the major agents for increasing number of serious hospital and community acquired infections. The aim of this study was to investigate the occurrence of the MRSA and mecA gene among nosocomial and environmental specimens in Kurdistan hospitals and determining the antibiotic resistance of the isolates. Materials and Methods: A total of 264 clinical and environmental Staphylococcus was isolated from Kurdistan medical University Hospitals, in February 2011 to June 2012 Iran, and their susceptibility patterns to different antibiotics were determined. Furthermore, agar screen method was used to determine oxacillin resistant isolates. Finally, using PCR, the oxacillin resistant isolates were tested for the presence of mecA gene. Results: In this study, from 88 (93.18%) Staphylococcus aureus isolates, 82 were found resistant to oxacillin using agar screen method and mecA gene was ...

Iranian Journal of Public Health, 2014

Iranian Journal of Public Health, 2014

Research in Molecular Medicine, 2015

Background: Methicillin resistant Staphylococcus aureus (MRSA) is one of the major agents for inc... more Background: Methicillin resistant Staphylococcus aureus (MRSA) is one of the major agents for increasing number of serious hospital and community acquired infections. The aim of this study was to investigate the occurrence of the MRSA and mecA gene among nosocomial and environmental specimens in Kurdistan hospitals and determining the antibiotic resistance of the isolates. Materials and Methods: A total of 264 clinical and environmental Staphylococcus was isolated from Kurdistan medical University Hospitals, in February 2011 to June 2012 Iran, and their susceptibility patterns to different antibiotics were determined. Furthermore, agar screen method was used to determine oxacillin resistant isolates. Finally, using PCR, the oxacillin resistant isolates were tested for the presence of mecA gene. Results: In this study, from 88 (93.18%) Staphylococcus aureus isolates, 82 were found resistant to oxacillin using agar screen method and mecA gene was detected in 66 strains (75%). Our results showed that the agar screen method is more reliable in determination of MRSA strains compared to PCR. Conclusion: In this research the studied MRSA were found with high prevalence and mecA was widespread in S. aureus isolates in Sanandaj.

Iranian Journal of Public Health, 2014

The sand accumulates at the well leads to increase in sand production resulting in lost productio... more The sand accumulates at the well leads to increase in sand production resulting in lost production and increased well maintenance cost. The main objective of this research is to evaluate sand produced from the field and to propose a suitable prevention sand method.Four samples of sand with different mass size are prepared for the test and then placed in a sieve shaker with openings in the decreasing order of sieve size. Sieves of sizes 2000, 1000, 500, 250, 125, 36 microns and a no sieve pan were used to sample the sand. Granular particles are accumulated on different sieves, which give the particle size distribution of the samples.From sieving analysis, the results showed that for well one the majority of the sand material is retained on the 500-size sieve. While, for the second sample the results showed that the percentage of sand accumulated on the 125 micron is the highest, which indicates that the sample consists of fine particles. Further, the highest percent weight retained o...

Iranian Journal of Public Health, 2014

Journal of the Medical Sciences, 2014

Advanced Biomedical Research, 2017

Background: Staphylococcus aureus strains that are Panton-Valentine leukocidin (PVL) positive cau... more Background: Staphylococcus aureus strains that are Panton-Valentine leukocidin (PVL) positive cause severe skin and soft tissue infections as well as necrotizing pneumonia. The presence of PVL gene is a marker for methicillin-resistant S. aureus; therefore, survey on prevalence and phylogenetic distribution of PVL is of great importance for public health. The aim of this research was molecular epidemiology survey of S. aureus PVL positive, isolated from two tertiary hospitals of Sanandaj. Materials and Methods: A total of 264 staphylococci isolates were collected from clinical specimens, hospital personnel and hospital environment of two tertiary hospitals of Sanandaj, in 2012 (Toohid and Besat). Bacterial cultures and biochemical tests were performed for S. aureus detection. Then, polymerase chain reaction (PCR) and repetitive sequence-based PCR (rep-PCR) were used for the determination of prevalence and molecular epidemiology of S. aureus PVL, respectively. Data were analyzed using the Fisher's exact test (P < 0.05). Results: From 264 staphylococci isolates, 88 (33.33%) were detected as S. aureus. Furthermore, 20 out of 88 (22.72%) strains of S. aureus were PVL positive according to PCR results. Rep-PCR showed six main clusters of S. aureus samples. PVL had similar clonality between different samples. No signifi cant relationship was observed between PVL positive S. aureus and rep-PCR patterns (P = 0.98). Conclusion: These results showed that a clone of S. aureus PVL positive has spread between the community and hospital settings. Therefore, appropriate measures are required to prevent the spread of staphylococci and other bacteria in hospitals.

International Journal of Enteric Pathogens, 2014

Background: Nano composites are widely used in medical sciences recently. Identification of chemi... more Background: Nano composites are widely used in medical sciences recently. Identification of chemical mutagens is an important issue in drug safety. Objectives: The aim of this study was to investigate mutagenicity and antibacterial activity of various generations of poly (amid amine) (PAMAM) dendrimers and agonic acid poly (amid amine) (PAMAM) Nano composite G2 on enteric pathogenic bacteria. Materials and Methods: Disc diffusion method, MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) determination were performed for antibacterial activity survey. Mutagenic properties were determined by Ames assay. Results: Various dilutions of PAMAM generations (G2, G3, G4 and G5) and agonic acid PAMAM Nano composite G2 had antibacterial effect on Escherichia coli, Salmonella enterica, Salmonella typhimurium, Enterococcus faecalis and Staphylococcus aureus. In Ames assay, reverted colonies were increased by PAMAM generations increasing. Moreover, reverted colonies Ames assay were lower when Nano composite G2 was applied. Conclusions: PAMAM generations and agonic acid PAMAM Nano composite G2 contain compounds with therapeutic potential and antibacterial characteristics, which can be used in medicine. Because some chemicals have mutagenic and carcinogenic properties, identification of these chemical is of great importance.

International Journal of Steel Structures, 2021

In this study, a new hybrid energy dissipation device is developed by combining two friction damp... more In this study, a new hybrid energy dissipation device is developed by combining two friction dampers (auxiliary and main fuse) in series to be used for the seismic control of two different earthquake intensities. Compared with the conventional friction dampers, the new hybrid damper has an advantage in that only the auxiliary fuse (with low sliding force) is activated for moderate earthquakes and both fuses work simultaneously for strong earthquakes. Cyclic loading tests of the combined hybrid dampers are carried out to evaluate their seismic energy dissipation capability. The obtained experimental force displacement indicates proper details of the new damper to create two performance levels. Finite element analyses of the test specimens are also carried out for comparison and have good agreement with the test results. Force–displacement characteristics, energy dissipation, and equivalent viscous damping are also derived and good agreement has been found. Moreover, it is demonstrated that by engaging the main fuse with non-loaded pretension bolts, the strength losses of the hybrid damper in the subsequent cycles are limited compared with the common friction dampers, which can be called the “resurrection-type” behavior of the main fuse in the main shocks. To evaluate the effects of the proposed damper, typical 3- and 9-story steel buildings are modeled and their seismic responses under 22 earthquake excitations are investigated using incremental dynamic nonlinear time-history. Comparison of incremental dynamic analysis (IDA) curves and their medians revealed that using a hybrid friction damper (HFD) reduces the probability of reaching all the defined damage states. Moreover, the reduction effect of HFD was recognizable in 9-story frames.