This paper investigated a room temperature resistive ammonia gas sensor based on a conductive polymer and N-doped graphene quantum dots (N-GQDs) dopant made on a transparent substrate with ...electrodes. The sensor fabricated with conductive polymer showed a good sensing response that increases considerably with the addition of N-GQDs. The sensing response of the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) to NH3 increased from 30.13% to 212.32% at 1500 ppm with the addition of 50 wt% N-GQDs. The response time of the N-GQDs doped sensor decreased to 6.8 min when compared with the sensor without N-GQDs and the stability of the sensor having combined N-GQDs and PEDOT-PSS was higher than that of the PEDOT-PSS sensor. Meanwhile, the structure and morphology of the sensing film are characterized by Fourier transform infrared spectroscopy and field emissions scanning electron microscopy.
Comprehensive data on drug‐resistant patterns of Acinetobacter baumannii isolates in developing countries is limited. We conducted a multihospital study to assess the rate and trend of drug‐resistant ...phenotypes in Ac. baumannii using standardized definitions and to determine the remaining therapeutic options against resistant phenotypes. The 401 nonduplicate isolates were collected from six hospitals which are geographically distributed across Tehran, Iran over a 3‐year period. Following PCR of blaOXA‐51‐like gene, susceptibility testing was performed against nine antimicrobial agent categories. Three hundred and ninety (97%) isolates were resistant to least two carbapenems; carbapenem‐resistant Ac. baumannii. The majority of isolates (366, 91·3%) were extensively drug resistant (XDR) and the rest of the isolates were classified as multidrug resistant (26, 6·8%) and susceptible (9, 2·2%). The rate of XDR‐AB slightly decreased from 93·8% in 2011 to 89·8% in 2013. A considerable decrease in resistance to doxycycline, minocycline and tigecycline was demonstrated. The XDR‐AB isolates showed susceptibility to gentamicin (10·4%), tobramycin (23%), ampicilin–sulbactam (30·1%), minocycline (32·8%), tigecycline (10·7%), doxycycline (21·6%), colistin (100%) and polymixin B (100%). We demonstrated the rising trend of resistance to all antibiotic categories except tetracyclines and folate pathway inhibitors. We found that the treatment options against XDR‐AB are extremely limited and each treatment alternative including even old, but safe, antibiotics might be considered.
Significance and Impact of the Study
The high frequency of drug‐resistant phenotypes including carbapenem‐resistant Acinetobacter baumannii, multidrug‐resistant, and extensively resistant has been demonstrated in Ac. baumannii isolates tested here. As the antibiotic resistance pattern of isolates varies in different geographical regions, this study can provide comprehensive information about the antibiotic resistance profile of Ac. baumannii isolates in Tehran. In addition, the resistance profiles could be effectively considered by clinicians to manage antibiotic therapy. This work also emphasizes on the prudent use of antibiotics and the monitoring of antibiotic susceptibility trend and rate.
Significance and Impact of the Study: The high frequency of drug‐resistant phenotypes including carbapenem‐resistant Acinetobacter baumannii, multidrug‐resistant, and extensively resistant has been demonstrated in Ac. baumannii isolates tested here. As the antibiotic resistance pattern of isolates varies in different geographical regions, this study can provide comprehensive information about the antibiotic resistance profile of Ac. baumannii isolates in Tehran. In addition, the resistance profiles could be effectively considered by clinicians to manage antibiotic therapy. This work also emphasizes on the prudent use of antibiotics and the monitoring of antibiotic susceptibility trend and rate.
This work presents a new analytical transmission line model for microstrip T-resonator dielectric constant measurement method in order to simplify the extraction of the complex dielectric ...permittivity of the substrate and increase its accuracy. The proposed new formula, which is based on the T-matrix equivalent circuit of the structure, is only dependent on the propagation and attenuation constants of the stub line. Two new formulas to determine the end effect of open-ended stub and the propagation constant parameters are also presented. As an example, a T-resonator is implemented on a 31 mil RO4003C substrate, and it is simulated and measured S-parameter results in the range of 1 MHz–8 GHz are used to calculate a complex dielectric constant of the substrate at each resonance frequency. A full-wave simulation is also used to confirm the accuracy of the proposed model. The comparison between the simulated and the measured S-parameters demonstrates a relative error of <1% over the frequency range.
Aims
The aim of this multi‐hospital study was to assess the in vitro activity of doripenem and its comparators, imipenem and meropenem, using the new CLSI breakpoints against a large population of a ...frequently isolated nosocomial pathogen, Acinetobacter baumannii.
Methods and Results
During a 2‐year period, four referral or tertiary hospitals submitted 400 isolates of Ac. baumannii for susceptibility testing using imipenem, meropenem and doripenem via disc diffusion and E‐test methods. A subset of 390 isolates was resistant to all three tested carbapenems. Doripenem and meropenem (MIC50, 32 μg ml−1) had comparable activity, albeit doripenem's activity was greater than imipenem (MIC50, >32 μg ml−1). A significantly higher proportion of the isolates were inhibited by doripenem than by imipenem at MIC values of 12, 16, 24 and 32 μg ml−1 (P < 0·05). The cumulative percentage of imipenem MICs was lower compared to its comparators. The comparison of resistance rate to imipenem and meropenem based on old and new breakpoints showed <1% difference. The overall agreement between the two susceptibility testing methods was ≥95%.
Conclusion
Doripenem has a slightly greater in vitro activity than imipenem in terms of zone breakpoints and MIC values, but its activity is comparable to meropenem.
Significance and Impact of the Study
Doripenem should be considered as a therapeutic option for monotherapy or combination therapy, particularly when the therapeutic options are limited.
Neutrophil-gelatinase-associated lipocalin (NGAL) is a biomarker of acute kidney injury. The aim of this study was to define a cut-off for NGAL in the early diagnosis of contrast-induced nephropathy ...(CIN) in patients with normal kidney function. We enrolled 121 patients with normal serum creatinine who underwent coronary angiography. NGAL was measured in urine before the procedure and 12 and 24 h afterward. CIN was defined as a 0.3 mg/dl increase in serum creatinine within 48 h after the procedure. Seven of 121 patients had CIN (5.8%). The NGAL levels in the 12- and 24-h urine samples of these patients were 30 (5-45) and 20 (15-40) ng/ml, respectively, whereas those in patients without CIN were 15 (5-45) and 15 (10-51) ng/ml, respectively (P = 0.8). In patients with CIN, the sensitivity and specificity of NGAL with a cut-off of 22.5 ng/ml were 71.4% and 57.9% in 12-h urine samples, with the negative predictive values (NPV) and positive predictive values (PPV) of 97.1% and 9.4%, respectively. In conclusion, we suggest that urine NGAL with cut-off point of 22.5 ng/ml has acceptable sensitivity and specificity for early diagnosis of CIN in patients with normal serum creatinine, but regarding NPV and PPV the best performance of this value is to rule out the CIN in patients at risk who received contrast media.
Scanning thermal microscopy (SThM) has been used to study Joule heating in conjugated polymer light‐emitting diodes (LEDs; see Figure). The operational temperature of the LED is found to be a strong ...function of device area: smaller LEDs exchange heat more efficiently with their surrounding environment. The results suggest that at high current density, Joule heating may be linked to device failure.
In 2001, Lee et al. (see ibid., vol.48, no.5, p.524-9, May 2001) proposed the use of GaN layers as a suitable material for surface-acoustic wave devices. They calculated the electromechanical ...coupling factor (k/sup 2/) for this material to be (4.3/spl plusmn/0.3)%. We have repeated their experiments and report a significantly lower value of k/sup 2/=(0.066/spl plusmn/0.003)% for a film thickness of /spl sim/0.1 times the acoustic wavelength.
Abstract Little is known about the toxin profiles, toxinotypes and variations of toxin Clostridioides difficile C ( tcdC ) in Iranian C. difficile isolates. A total of 818 stool specimens were ...obtained from outpatients ( n = 45) and hospitalized patients ( n = 773) in Tehran, Iran, from 2011 to 2017. The 44 C. difficile isolates were subjected to PCR of toxin C. difficile A ( tcdA ), toxin C. difficile B ( tcdB ), tcdA 3′-end deletion, toxinotyping and sequencing of the tcdC gene. Thirty-eight isolates (86.36%) were identified as tcdA and tcdB positive, and the remaining six isolates (13.63%) were nontoxigenic. All tcdA - and tcdB -positive isolates yielded an amplicon of 2535 bp by PCR for the tcdA 3′ end. Fourteen (36.84%), seventeen (44.73%) and seven (18.43%) isolates belonged to wild-type, toxin C. difficile C subclone3 ( tcdC-sc3 ) and tcdC-A genotype of tcdC , respectively. Thirty-one isolates (81.57%) belonged to toxinotype 0, and seven isolates (18.42%) were classified as toxinotype V. This study provides evidence for the circulation of historical and hypervirulent isolates in the healthcare and community settings. Furthermore, it was also demonstrated that the tcdC-A genotype and toxinotype V are not uncommon among Iranian C. difficile isolates.
The atrial natriuretic peptide (ANP) gene expression and some of its related single-nucleotide polymorphisms have been well established as a characterized biomarker of cardiovascular diseases. In the ...present study, we aimed to evaluate the potential association between one of the introduced ANP gene polymorphisms of 2238 T/C (rs5065) with coronary artery disease (CAD) in an Iranian population.
A total of 573 patients with CAD according to angiography reports and 293 controls without any evidence of CAD were enrolled. Allelic discrimination of the single-nucleotide polymorphism rs5065 in both groups was performed using a High Resolution Melt technique in real-time PCR analysis.
With respect to the prevalence of different genotypes of rs5065 polymorphism, the frequency of the T allele in the CAD group was significantly lower in CAD than that in the non-CAD group (59.7 vs. 65.1%, P=0.032). A significant inverse association was also found between the frequency of T allele and severity of CAD assessed by the Gensini score; the average of this score in T-allele carriers was 38.6±41.6 and that in C-allele carriers was 57.7±46.3 (P≤0.0001). Using multivariable linear regression modeling with the presence of baseline variables, the presence of the rs5065 ANP T allele could predict decreased severity of CAD assessed by the Gensini score in our population.
The presence of the rs5065 ANP polymorphism is potentially associated with a reduced risk of CAD as well as with reduced severity of CAD independent of the general risk factors of CAD.
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