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Temperature Dependence of Electrical Characteristics of Carbon Nanotube Field-Effect Transistors: A Quantum Simulation Study
Ali Naderi,S. Mohammad Noorbakhsh,Hossein Elahipanah
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/532625
Abstract: By developing a two-dimensional (2D) full quantum simulation, the attributes of carbon nanotube field-effect transistors (CNTFETs) in different temperatures have been comprehensively investigated. Simulations have been performed by employing the self-consistent solution of 2D Poisson-Schrödinger equations within the nonequilibrium Green's function (NEGF) formalism. Principal characteristics of CNTFETs such as current capability, drain conductance, transconductance, and subthreshold swing (SS) have been investigated. Simulation results present that as temperature raises from 250 to 500 K, the drain conductance and on-current of the CNTFET improved; meanwhile the on-/off-current ratio deteriorated due to faster growth in off-current. Also the effects of temperature on short channel effects (SCEs) such as drain-induced barrier lowering (DIBL) and threshold voltage roll-off have been studied. Results show that the subthreshold swing and DIBL parameters are almost linearly correlated, so the degradation of these parameters has the same origin and can be perfectly influenced by the temperature.
Determination of the MIC of Antibiotics for Gram Negative Microorganisms Isolated from the Sterile Sites of Children Hospitalized in Rasool Akram Hospital
S Noorbakhsh,M Farhadi,A Tabatabaei
Iranian Journal of Pediatrics , 2006,
Abstract: Background: The increased prevalence of resistant gram negative organisms in our hospital is documented in our previous retrospective study during 1996-1998. The present study was conducted to determine the resistance frequency of gram negative organisms responsible for infection in children. Methods: In a descriptive prospective study within 2 years (2002-2003). We surveyed 101 children aged 1 month-14 years hospitalized in pediatric and ENT wards of Rasool Akram hospital selected by simple sampling. All gram negative organisms isolated from blood, CSF and other sterile sites (middle ear; mastoid; sinus; trachea) were evaluated first by disc diffusion and then E-testing for MIC to find appropriate antibiotics for the isolated organisms. Findings: The isolated germs consisted of Pseudomonas aeroginusa (47.5%), Klebsiella pneumoniae (22.8%); E. coli (17.8%), entrobacter and Acinetobacter (4.9%), Fusobacter and Salmonella paratyphi (1%). Resistance of pseudomonas was high (80%) for gentamycin; cotrimoxazole and rifampin; moderate (50%) for ceftazidim and amikacin, but low (<15%) for imipenem. Resistance of Klebsiella to ampicillin, gentamycin, amikacin, cotrimoxazole and ciprofloxacin was high (70%), but showed lower resistance for ceftriaxone and imipenem (30%). More than 90% of E. coli was resistant to ampicillin, cotrimoxazle, with moderate resistance (20%) to gentamycine and cephalexin. Resistance of Entrobacter to ceftriaxon was less than 40%. More than 80% of Acinetobacter was sensitive to amikacin and cotrimoxazole. Conclusion: Ceftazidime, despite increasing resistance of pseudomonas to it, combined with amikacin is still adequate for empiric treatment in admission. For other resistant types, cefepime or imipenem is useful. For Klebsiella pneumoniae, ceftriaxone and imipenem; for E. coli, amikacin or ceftriaxon; and if it does not respond imipenem or azteronam. Cefriaxon is the best choice for early treatment of Enterobacter infections.
Diagnostic value of urinary antigen Streptococcus pneumoniae in children With pneumonia: A case control study
Noorbakhsh, S,Mirmohamadpoor,A,Tabatabaee, A
Medical Laboratory Journal , 2010, DOI: http://www.goums.ac.ir/mljgoums/index.php?slc_lang=en&sid=1
Abstract: Background and objectives: The aim of this study was the detection ofS.pneumoniae infection by rapid urinary test and blood culture in childrenwith pneumonia in comparison with healthy children.Material and Methods: This case control study was carried outin pediatric ward of Rasoul Akram hospital in Tehran, Iran (2006 -200 ).Fifty-four Community acquired pneumonia (CAP) and 50 healthychildren were selected by simple sampling. The urinary antigen detectiontest (BINAX NOW co.) was performed on both cases and controls; andblood culture was done for the cases suffered from Pneumonia.Results: Pneumococcal antigenuria is detected in 31.5 % of CAP and 6 %of controls groups. There is Significant difference between cases andcontrols (fisher test; CI 95%, P =0.01). None of the children with nonpneumococcalPneumonia (positive culture) has antigenuria.Conclusion: The possibility of diagnosis of pneumococcal pneumonia inchildren, by means of blood culture, is low. Thirty-one percent of CAP isdue to S.pneumonia, by using the rapid antigenuria test. There fore, werecommend using rapid urinary antigen test, in addition to blood Culturetest.Key words: CAP (community-acquired pneumonia); S pneumoniaeurinary antigen test (BINAX now), Blood culture, Children
Factors Affecting, Urease Enzyme Activity in some Soils in Isfahan Province
F. Noorbakhsh,S. Hajrasuliha,G. Emtiazy
Journal of Science and Technology of Agriculture and Natural Resources , 2001,
Abstract: The urease enzyme plays an important role in the efficient use of urea fertilizer and some environmental risk assessment. Urease activities in 20 different soil samples of arid to semi-arid regions of Isfahan Province were determined and their correlations with some soil physical, chemical and biological characteristics were studied. Urease activities range from 5.3 to 79.2 μg NH4+ g-1 soil 2hr-1. Results indicated that soil organic carbon was significantly correlated with urease activity (r=0.899***). None of sand, silt and clay percentages were significantly correlated with urease activity. Total nitrogen was significantly correlated with urease activity (r=0.797***). Electrical conductivity of saturated paste extracts were also negatively correlated (r=-0.499*) but sodium adsorption ratio (SAR), pH, equivalent calcium carbonate and cation exchange capacity failed to be correlated significantly with urease activity. No significant correlations were found between urease activity and total bacteria (on nutrient agar) or total fungi (on potato dextrose agar), but the bacteria that could colonize urea-agar media were significantly correlated with urease activity (r=0.47*). Multiple stepwise regression analysis showed that organic carbon accounted for most of the variation in urease activity.
Interpretation of the Widal Test in Infected Children
S Noorbakhsh,S Rimaz,AA Rahbarimanesh,S Mamishi
Iranian Journal of Public Health , 2003,
Abstract: Typhoid fever is endemic in Iran. Isolation of S. typhi is a gold standard for diagnosis. Laboratory diagnosis of S. typhi infection relies on serological tests such as the Widal test. This study describes seroprevalence of TO and TH antibody in nonfebrile healthy and febrile with non-typhoid illness. For detection of sensitivity and specificity of Widal test in typhoidal fever diagnosing Widal test was performed on serum specimen of the culture-positive cases of typhoid fever in children aged between 1 and14 years in Tehran, A cross –sectional study was carried out. Widal tests were performed on 40 healthy nonfebrile children; 40 patients with non typhoidal febrile illness and 58 cases with bacteriologically documented typhoid fever specificity, sensitivity, positive and negative predictive values and the efficacy of the test were determined. Agglutinin titres ≤ 1:40 were considered normal for TO and TH at 96.25% and 93.75% confidence levels, respectively. Titres above these levels. TO>1:40 and TH>1:40, were considered to be abnormal. 25% of patients showed no response to either agglutinin (TH and TO); and 44.8% of cases shown no response for TO agglutinin. TO >1/320 was not seen in any cases but TH >1/320 was detected in 20.6% of cases. Salmonella typhi TO and H agglutinin titers > 1/40 were considered to be significant with 75.86% sensitivity and 93.75% specificity, respectively. The positive and negative predictive values were 89.79% and 84.26%, respectively. This study suggests that seroprevalence studies in healthy children can help as validate use for particular serological cut-off point.
Toxoplasmosis in Primiparus Pregnant Women and Their Neonates
S Noorbakhsh,S Mamishi,S Rimaz,SHR Monavari
Iranian Journal of Public Health , 2002,
Abstract: The prevalence of primary infection with T. gondii in pregnant women and risk of congenital infection in their neonates in various parts of Tehran are unknown. The prevalence rate of antibodies to T. gondii ranges from 24% in Tehran to 62.7% in Babol. This study describes the epidemiology of toxoplasma infection in pregnant women in Tehran and risk factors of congenital toxoplasmosis in newborn among preterm infants and full- term infants born from these mothers. A cross sectional study was carried out in 140 primiparus women living in various part of Tehran. Initially from each case a questionnaire was completed by the authorized physician, followed by clinical exams in newborns. The birth certificate was the data source used for such as gestational age, birthweigt, etc. The centrifuged blood specimens from all pregnant women are screened using an assay for Toxoplasma- specific IgM and IgG based on preliminary evidence in Iran. Specific toxo- IgM was positive in 7.1% (90% of them were also IgG positive) , toxo – IgG was positive in 34.3% of mothers. Mean age of IgG positive mothers (22.49±4.22), mean age of IgM positive mothers (19.90± 3.48). There were significantly differences between living place of mothers and IgG positive (p=0.007) . There were significantly differences between living place of mothers (East and central) and IgM positive (Fisher test = 0.023). Elaborating an epidemiological profile and risk correlates might help focus prenatal education and newborn screening strategies. Prenatal screening could be more easily justified in central part of Tehran because low incidence populations detected and probably treatment of mothers infected during pregnancy led to lower rates of transmission to the newborn. In contrast, in eastern part of Tehran due to high seroprevalence rate detected, newborn screening is relatively inexpensive and efficient.
Determination Of Appropriate Antibiotic In Bacterial Meningitis Of Children Based On MIC
Noorbakhsh S,Siadati SA,Rimaz S,Mamishi S
Tehran University Medical Journal , 2005,
Abstract: Background: Bacterial meningitis is one of the most serious infections in infants and children. Three organisms include S.Pneumo;N.mening;H.Influ are the most common cause of meningitis in children between 2M-14y age.Etest is a new method for determination the MIC of some antimicrobial drugs in agarose .This method is useful for some organisms like as S .Pneumo; N.mening; H.Influ;sensitive Streptococcus and anaerobic ;aerobic gram negative. Materials and Methods: In this descriptive cross sectional study; In 57 suspected meningitis children ; organisms isolated from blood; CSF or other sterile boy fluid after culturing and antibiogram;. .MIC of someorganisms detected by Etest method. Results: Streptococcuswas the most prevalent ( 70%) and S.pneumon( 90% of all Streptococcus); H.infl 2%;N.mening 4%and L.monocyt 6%(more than expected);Gram negative (Ecoli; Klebsiella; entrobacter and psudomona) 18%. There was significant difference (P =0.01)in type of organisms between age groups. S.pneumonia was more frequent in children > 2 year ;N.meningitis in>4yr old .Site of isolation :blood; CSF (35.8*;28.3%)other sterile site 18.4%;concomitant positive culture in two site:17%.Mean age in Streptococcus was significantly different with Listeria (p=0.05); N.meningitis (p=0.04);H.influ (p=0.04);.but no difference with Staphylococcus;Klebsiella and E.coli Two type of H.inf were sensitive to Ampici or chloram ;both of them were sensitive to ceftiaxon. GBS were sensitive to PNC or Ampici Strep.nonAnonBnon- Cotrimoxazol>32mic/ml /PNC >256mic/ml/ Vanco>256mic/ml Strep.D: Cotrimoxazol>0.062mg/ml/ /PNC >0.016mic/ml/Imipenem>0.032mic/ml. Strep Pneumonia: All fo them were sensitive except 3 cases /Cotrimoxazol>2ic/ml /PNC =0.01mic/ml/Vanco>0.125mic/ m Vanco>0. 25mic/ ml/.Cotrimoxazol>2ic/ml / PNC =0.01mg/ml Vanco>0.125mic/ ml / Cotrimoxazol>2mic/ml /MIC-PNC >0.016mic/ml Therefore high dose of PNC is adequate for S.pneu ;because of Interm resistance to PNC All 3 N.menin were sensitive to PNC;Chlora;Ceftria and vanco Resistant to all drugs and high MIC for cefotaxime;CIPRO>32mic/ml. E coli: Pseudomona Aerogenosa:: Ceftriaxon>256mic/ml/ /Genta>0.038mg/ml Imipenem>32mic/ml. Klebsiella; only Sensitive to Cipro Staph .Aureous:Sensitive to Clinda;Cipro;Chlora;Resistant toCeft;PNCand Cotri Conclusion: Most type of N.meningitidis;H.inf and S.pneumonia were sensitive to many drugs. Only minority of them were resistant to Ampicillin but sensitive to chloramphenicol and vice versa. limited number of pneumococcal resistance to penicillin is medium resistance( MIC:0.1-1) .we can treat this
Study of Antibiotics Resistance in Pediatric Acute Bacterial Meningitis with E-Test Method
AR Fahimzad,S Mamaishi,S Noorbakhsh,A Siadati
Iranian Journal of Pediatrics , 2006,
Abstract: Background: Appropriate treatment of bacterial meningitis especially in children is a important problem due to multiple drug resistance. The determination MIC of conventional antibiotics for bacterial meningitis with quantitative E. test is exactly practical and essential. We studied MIC of conventional antibiotics in pediatric acute bacterial meningitis older than two months, center children hospital, 1382-1384. Methods: In this prospective and cross sectional process research we measured MIC of antibiotics in 30 positive bacterial culture in CSF or blood with quantitative E. test and compared with qualitative disk diffusion test. Findings: Antibiotic resistance of 10 Haemophilus influenzae type b patient was : ampicillin resistance in 90%, co – Amoxiclave R. in 10%, chlorampheicol R. in 40%, third gerenation cephlosporins R.( ceftriaxone and cefotaxime) in 0% and cotrimoxazole R. in 100% and antibiotic resistance of 20 streptococcous pneumoniae patient was :penicillin R. in 35% , chloramphenical R. in 10%, third generation cephalosporins R. in 5% ,rifampin R. in 10% and cotrimoxazole R. in 60% .In comparison of two methods E-Test and Disk Diffusion we found insignificant difference. Conclusions: Antibiotic Resistance of our study is compatible with other studies .Therefore it seems that composition of ampicillin and chloramphenicol as empiric therapy for bacterial meningitis for many years ago ,aren’t appropriate today and third generation cephalosporins alone or with vancomycin is a suitable therapy.
Molecular characterization of 26S proteasome regulatory subunit in dermatophyte pathogen Trichophyton verrucosum
M Fouladvand, B Naeimi, S Rezaie, F Noorbakhsh, MR Safari
African Journal of Biotechnology , 2009,
Abstract: Trichophyton verrucosum is a zoophilic dermatophyte, which causes dermatophytosis infection in human as well as animals. 26S proteasome is an important protein in eukaryotic cells that is involved with degradation of unneeded or damaged proteins, when tagged with ubiquitin. In this study, we characterized the 26S Proteasome regulatory subunit gene in dermatophyte pathogen T. verrucosum. High molecular weight DNA has been isolated from T. verrucosum and utilized with pairs of specific nucleotides primers, designed from highly preserved regions of the 26S proteasome regulatory subunit genes. Obtained DNA fragments were sequenced and the results were analyzed in GenBank. This DNA fragment, which contains no intron within its open reading frame, encodes a polypeptide with 332 amino acids. The characterized PCR fragments revealed significant homology with other 26S proteasome regulatory subunit genes in GenBank.
Staphylococcal Superantigens in Synovial Fluid of 62 Patients With Arthritis
S Noorbakhsh,A Tabatabaei,M Talebi-Taher
Tehran University Medical Journal , 2012,
Abstract: Background: Determining the etiologic causes of septic arthritis is of the most importance. Goal of this study was to investigate presence of staphylococcal enterotoxins A, B, C and Toxic Shock Staphylococcal toxin-1 in the synovial fluid of patients with arthritis. Methods: This cross-sectional study was performed in the Pediatric and Orthopedic Wards of Hazrat Rasoul Hospital in Tehran, Iran during 2008- 2010. Gram stains, conventional cultures, direct detection of soluble bacterial antigens were used to detect H. influenza, S. pneumonia, group B streptococci, and N. meningitidis while Latex particle agglutination test was used for staphylococcal supper antigens (by enzyme immunoassays) upon synovial fluid tapping of 62 individuals (5 mo to 16 yrs, mean=11 3.8 yrs). P<0.05 was considered statistically significant. Results: Positive SF cultures (n=11): 5 positive cases of S. aureus; 5 S. pneumonia; 1 H. influenza, and 1 Klebsiella. Positive gram stains: 10%; and positive LPA: 4%. Staphylococcal arthritis was diagnosed in 7 (39%) cases upon positive culture or positive gram stain. The most common type was TSST-1 (47%) and the least common was enterotoxin B (18%). Isolation of S. aureus (positive culture) was correlated to presence of enterotoxin A in synovial fluid but not to enterotoxins B, C or TSST-1. Conclusion: Staph. aureus had a prominent role in arthritis. 47% of cases with negative culture for S. aureus had at least one type of staphylococcal super antigens in the synovial fluid. Searching for antigens of usual organisms or staphylococcal supper antigens could be helpful for diagnosis and subsequent treatment.
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