Structural and dielectric behaviour of barium substituted lead zinc niobate

212-219The polycrystalline samples of (Pb1xBax)(Zn1/3Nb2/3)O3 (PBZN) ceramics have been synthesized by the columbite precursor method. X-ray diffraction analysis of PBZN synthesized for x = 0.15, 0.25, 0.35 and 0.50 shows a cubic perovskite phase at room temperature. The changes in the structures are observed with increasing Ba contents in PBZN. The dielectric dispersion of the solid solutions has been studied as a function of temperature in the frequency range 100 Hz-1MHz. The temperature variation of the real components (ƐƐ) at different frequencies of the dielectric permittivity shows a broad maximum. The diffuse peaks in versus T confirm the relaxor behaviour of PBZN. The changes in the relaxor properties of the compounds are found to be compositional dependent. The frequency dependence of Tm in these compounds with barium substitution is modeled using Vogel-Fulcher relation

Higher prevalence of multidrug-resistant extended-spectrum β-lactamases producing Escherichia coli in unorganized pig farms compared to organized pig farms in Mizoram, India

Aim: The present study was conducted to record the prevalence of multidrug-resistant (MDR), extended-spectrum β-lactamases (ESBLs) producing Escherichia coli from pig population of organized and unorganized farms of Mizoram and to record the presence of ESBLs, non-ESBLs, and integrons. Materials and Methods: Fecal samples were collected from pigs under organized (n=40) and unorganized (n=58) farms of Mizoram. Samples were processed for isolation and identification of E. coli by conventional techniques, BD Phoenix™ automated bacterial system, and polymerase chain reaction (PCR) based confirmatory test. All the isolates were subjected to antimicrobial sensitivity test by disk diffusion assay and ESBLs production by double-disk synergy test (DDST). The ESBLs producing isolates were subjected to PCR for determination of ESBLs genes and all the isolates were screened for non-ESBLs genes and integrons by PCR. Results: A total of 258 E. coli was isolated and identified from organized (n=120) and unorganized farms (n=138). Majority of the E. coli isolates exhibited high level of resistance against amoxicillin (Ax) (81.78%), cefalexin (85.42%), co-trimoxazole (50.78%), sulfafurazole (69.38%), tetracycline (65.89%), and trimethoprim (TR) (51.94%). Statistically highly significant (p<0.01) variations in resistance among the isolates from organized and unorganized farms were recorded in case of Ax, ampicillin, cephalexin, ciprofloxacin, co-trimoxazole, gentamicin, piperacillin, and TR. By DDST, 65.89% isolates were recorded as ESBLs producer, of which 82/120 (68.33%) and 88/138 (63.77%) were from organized and unorganized farms, respectively. A total of 29/258 (11.24%) isolates were positive for at least one ESBLs gene. blaTEM was most frequently (9.69%) gene, followed by blaCTX-M (5.04%) and blaCMY (0.78%). Altogether, 6 (5.00%), 4 (3.33%), and 2 (1.67%) isolates from the organized farms were positive for blaCTX-M, blaTEM, and blaCMY genes, respectively. Similarly, 21 (15.22%) and 7 (5.07%) isolates from the unorganized farms were positive for blaTEM and blaCTX-M genes, respectively. None of them were positive for blaSHV genes. Altogether 57 (22.09%), 9 (3.49%), 66 (25.58%), 78 (30.23%), 21 (8.14%), and 18 (6.98%) isolates were positive for tetA, tetB, sul1, sul2, aadA, and dfrla genes, respectively. The prevalence of non-ESBLs genes was higher in the E. coli isolates from the unorganized farms than organized farms. Conclusion: MDR and ESBLs producing E. coli are circulating among the pigs and their environment in Mizoram. Pigs under unorganized farms exhibited higher level of resistance against majority of the antimicrobials, including third-generation cephalosporins, which might be an indication of overuse or misuse of antibiotics under the unorganized piggery sectors in Mizoram