Controlling the Magneto-Optical Response in Ultrathin Films of EuO1-x via Interface Engineering with Ferroelectric BaTi2O5.

Utilizing pulsed laser deposition, a film of EuO1-x was deposited onto a Si(001) substrate with MgO buffer and compared to the same heterostructure with an additional BaTi2O5 thin film on top of the EuO1-x surface. X-ray diffraction (XRD) indicates the films crystallize into a preferred EuO(111) orientation; it also reveals the clear presence of EuSi2, which suggests Si or Eu diffuses across the MgO buffer layer. EuO1-x films exhibit a ferromagnetic (FM) signature and temperature-dependent exchange bias, indicated by MOKE measurements, suggesting the presence of a magnetic order well above the EuO Curie temperature with possible origins in charge carrier density near the interface. In comparison, an antiferromagnetic character persists well above the EuO Curie temperature of 69 K and the enhanced Curie temperature of 150 K for BaTi2O5 films grown on the EuO1-x films. The antiferromagnetic behavior is not seen in thicker EuO1-x thin films when integrated with other ferroelectric (FE) phases of the BaO-TiO2 system, suggesting an origin in the perturbed charge population at the BaTi2O5/EuO1-x interface.

Freshwater salmon aquaculture in Chile and transferable antimicrobial resistance.

Large amounts of antimicrobials are used in salmonid aquaculture in Chile. Most are used in marine aquaculture, but appreciable amounts are also employed in freshwater aquaculture. Much research and many publications have examined transferable antimicrobial resistance in bacteria isolated from marine salmon farms, but much less attention has been paid to this area in freshwater salmon farming. A recent paper by Domínguez et al. (2019) has as least in part remedied this situation. We now comment on some of its interpretations and have attempted to point out its areas of strength and weakness in light of the published scientific literature. Seen in this setting, the important results presented by Domínguez et al. (2019) underline the need for increased awareness of the challenge to animal and human health posed by excessive use of antimicrobials in aquaculture.

Ultrathin Chromia on a Hexagonally-Ordered d0 Ferromagnet: Evidence of Interfacial Exchange Bias at the Cr2O3/TiO2-x Interface.

Heterostructures consisting of 10 Šthick chromia films and 50 Šthick titania films display significant exchange bias at and above room temperature. Chromia films ∼10 Šthick were deposited by molecular beam epitaxy (MBE) of Cr at room temperature in ultrahigh vacuum on 50 Šthick TiO2-x(111) films (x < 0.3) also deposited epitaxially by MBE on Al2O3(0001). Cr deposition yields increased Ti(III) formation in the titania substrate and the formation of a Cr2O3 overlayer, without Cr/Ti interfacial mixing, as determined by in situ photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). In situ low-energy electron diffraction (LEED) and XPS data indicate that the chromia overlayer is hexagonally ordered and ∼10 Šthick. Longitudinal and polar magneto-optic Kerr effect (MOKE) measurements at 285-315 K provide evidence of strong exchange bias between the boundary layer magnetization of chromia and the ferromagnetic substrate. These data demonstrate the robust room-temperature interaction of the boundary layer magnetization of a multiferroic antiferromagnet with a d0 ferromagnetic substrate.

Synthesis of 99mTc-Rifabutin: A Potential Tuberculosis Radiodiagnostic Agent.

BACKGROUND: Rifabutin (RFN) is bactericidal antibiotic with a very broad spectrum of activity against gram positive & gram negative organisms including Pseudomonas aeruginosa and specifically Mycobacterium tuberculosis. RFN inhibits DNA dependent RNA polymerase activity in susceptible cells. In the instant work, the therapeutic characteristics of RFN were intended for diagnostic rationale by labeling it with 99mTc (Technetium-99m). OBJECTIVE: The 99mTc labeled RFN (99mTc-RFN) was investigated for labeling capacity, steadiness in saline & serum, in vitro Mycobacterium tuberculosis (MBT) uptake & distribution in MBT stained animal model rats. METHOD: It was found that 99mTc-RFN prepared by mixing 2 mg of RFN, 2.5 mCi sodium pertechnetate, 150 µg stannous chloride at pH 5.4 gave highest yield after 30 minutes and was intact above 90 % after 240 min at room temperature in saline. RESULT: The 99mTc-RFN showed a stable profile in serum at 37 °C and impurities appeared up 16 h was 15.20 %. The maximum in vitro MBT uptake observed in live strain was 71.75 ± 0.75 %. The premier uptake observed in the MBT infected site (target site) was 14.15 ± 0.00 %, in animal model rat. CONCLUSION: Higher labeling capacity, steadiness in saline & serum, higher MBT uptake, maximum uptake in the MBT infected sites and precise imaging posed 99mTc- RFN as an alternate radio-drug for tuberculosis scintigraphy.

Antimicrobial resistance and antimicrobial resistance genes in marine bacteria from salmon aquaculture and non-aquaculture sites.

Antimicrobial resistance (AR) detected by disc diffusion and antimicrobial resistance genes detected by DNA hybridization and polymerase chain reaction with amplicon sequencing were studied in 124 marine bacterial isolates from a Chilean salmon aquaculture site and 76 from a site without aquaculture 8 km distant. Resistance to one or more antimicrobials was present in 81% of the isolates regardless of site. Resistance to tetracycline was most commonly encoded by tetA and tetG; to trimethoprim, by dfrA1, dfrA5 and dfrA12; to sulfamethizole, by sul1 and sul2; to amoxicillin, by blaTEM ; and to streptomycin, by strA-strB. Integron integrase intl1 was detected in 14 sul1-positive isolates, associated with aad9 gene cassettes in two from the aquaculture site. intl2 Integrase was only detected in three dfrA1-positive isolates from the aquaculture site and was not associated with gene cassettes in any. Of nine isolates tested for conjugation, two from the aquaculture site transferred AR determinants to Escherichia coli. High levels of AR in marine sediments from aquaculture and non-aquaculture sites suggest that dispersion of the large amounts of antimicrobials used in Chilean salmon aquaculture has created selective pressure in areas of the marine environment far removed from the initial site of use of these agents.

Synthesis of (99m)Tc labeled temafloxacin complex and biodistribution in male Wistar rats artificially infected with Streptococci pneumonia.

BACKGROUND: Radiotracers techniques are offering a unique way to diagnosis deep tissue infection in its early stages. The radiotracers including radio-antibiotics have shown promising results in the early diagnosis of infection and its discrimination from infectious foci but wide ranges of microorganisms still poses threats. OBJECTIVES: Synthesis of Technetium-99m ((99m)Tc)-temafloxacin (TMC) complex for the localization of in vivo Streptococci pneumoniae infection in the early stages. MATERIAL AND METHODS: The (99m)Tc-TMC complex was prepared by adding 50 µg of stannous chloride (SnCl2) with 37 MBq (0.5 mL) of sodium pertechnetate (Na(99m)TcO4-) at a pH of 5.2. Then 1 mg of the TMC was added to the mixture followed by incubation at room temperature for 10 min. The same procedure was repeated by changing the amount of the SnCl2 from 50 to 250 µg along with the TMC from 2 to 5 mg and Na(99m)TcO4- from 74 to 185 MBq. In higher concentrations of cysteine the stability of the (99m)Tc-TMC complex was evaluated. In vitro Streptococci pneumoniae uptake was investigated to validate the accuracy and preciseness of the (99m)Tc-TMC complex. In vivo uptake of the (99m)Tc-TMC complex was evaluated in ten (10) normal male Wistar rats (MWR) (140-160 g) divided into two groups (I and II). RESULTS: Maximum stability of 98.00 ± 0.34% at 30 min after reconstitution was observed by mixing 2.5 mg of TMC, 100 µg of SnCl2 with 74 MBq of the Na(99m)TcO4-. The stability of the complex remained 90% up to 4 hours. In serum the complex showed stability up to 16 hours. A saturated in vitro binding was noted with live Streptococci pneumoniae. In the infected region (left thigh) of the MWR, almost five times higher uptake was observed as compared to the inflamed and normal muscles. CONCLUSIONS: The above results confirm the suitability of the (99m)Tc-TMC complex as a potential Streptococci pneumoniae infection localizing agent.

A brief multi-disciplinary review on antimicrobial resistance in medicine and its linkage to the global environmental microbiota.

The discovery and introduction of antimicrobial agents to clinical medicine was one of the greatest medical triumphs of the 20th century that revolutionized the treatment of bacterial infections. However, the gradual emergence of populations of antimicrobial-resistant pathogenic bacteria resulting from use, misuse, and abuse of antimicrobials has today become a major global health concern. Antimicrobial resistance (AMR) genes have been suggested to originate from environmental bacteria, as clinically relevant resistance genes have been detected on the chromosome of environmental bacteria. As only a few new antimicrobials have been developed in the last decade, the further evolution of resistance poses a serious threat to public health. Urgent measures are required not only to minimize the use of antimicrobials for prophylactic and therapeutic purposes but also to look for alternative strategies for the control of bacterial infections. This review examines the global picture of antimicrobial resistance, factors that favor its spread, strategies, and limitations for its control and the need for continuous training of all stake-holders i.e., medical, veterinary, public health, and other relevant professionals as well as human consumers, in the appropriate use of antimicrobial drugs.

Prevalence of antibiotic resistance genes in the bacterial flora of integrated fish farming environments of Pakistan and Tanzania.

The use of a wide variety of antimicrobials in human and veterinary medicine, including aquaculture, has led to the emergence of antibiotic resistant pathogens. In the present study, bacteria from water, sediments, and fish were collected from fish farms in Pakistan and Tanzania with no recorded history of antibiotic use. The isolates were screened for the presence of resistance genes against various antimicrobials used in aquaculture and animal husbandry. Resistant isolates selected by disk diffusion and genotyped by Southern hybridization were further screened by polymerase chain reaction (PCR) and amplicon sequencing. The prominent resistance genes identified encoded tetracycline [tetA(A) and tetA(G)], trimethoprim [dfrA1, dfrA5, dfrA7, dfrA12, and dfrA15], amoxicillin [bla(TEM)], streptomycin [strA-strB], chloramphenicol [cat-1], and erythromycin resistance [mefA]. The int1 gene was found in more than 30% of the bacterial isolates in association with gene cassettes. MAR indices ranged from 0.2 to 1. The bla(NDM-1) gene was not identified in ertapenem resistant isolates. It is hypothesized that integrated fish farming practices utilizing domestic farm and poultry waste along with antibiotic residues from animal husbandry may have contributed to a pool of resistance genes in the aquaculture systems studied.

DNA gyrase and topoisomerase IV mutations in quinolone-resistant Flavobacterium psychrophilum isolated from diseased salmonids in Norway.

Flavobacterium psychrophilum is the causative agent of the recognized diseases 'bacterial coldwater disease' and 'rainbow trout fry syndrome' and is found in many farmed freshwater and marine fish species. In Norway, the bacterium has mainly been isolated from Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.). In the present study, 26 isolates from Norwegian farmed salmonids were examined. All isolates were tested for susceptibility towards various antibacterial drugs by the disk diffusion method, and minimum inhibitory concentration values for oxolinic acid and flumequine were established for selected isolates. All isolates from rainbow trout displayed reduced susceptibility towards quinolones, while brown trout and Atlantic salmon isolates were susceptible. The quinolone resistance determining regions (QRDRs) of the gyrA, gyrB, parC, and parE genes were sequenced. Sequence analysis of the QRDR of gyrA in quinolone resistant isolates revealed a threonine:arginine amino acid substitution at position 82 in all 16 isolates from Norwegian rainbow trout and a single reference strain isolated from rainbow trout in Sweden. No evidence for plasmid-mediated quinolone resistance was found in any of the isolates. Pulsed-field gel electrophoresis and phylogenetic analysis of parC and gyrB sequences indicate a clonal relationship between rainbow trout isolates.