Aim
Shiga toxin‐producing Escherichia coli (STEC) cause bloody diarrhoea, kidney failure and occasionally death. However, identifying the source of infection caused by STEC other than serogroup O157 ...is hampered by the availability of sensitive methods for detecting these pathogens. In this study, we developed novel tools for detecting E. coli O55 that is potentially associated with human outbreaks.
Methods and Results
Overall specificity of immuno‐magnetic separation (IMS) beads coated with anti‐O55 serum was good with exception of cross‐reactivity with E. coli O22 and O23, which was eliminated using an O55‐specific PCR. Limit of detection for E. coli O55 using O55‐IMS beads in spiked cattle faeces was on average 50 CFU per ml (range 1–90), and improved to <10 CFU per ml using the O55‐specific PCR, following IMS on samples enriched for 2 h with E. coli O55. Application of these tools to test cattle faeces collected on‐farm allowed the isolation of O55:H19, which through whole genome sequencing was compared to STEC O55:H7 human outbreak strains.
Conclusion
These tools provide a sensitive method which could be used to screen samples for STEC O55, whether environmental or human clinical.
Significance and Impact of the Study
Several human outbreaks reported in England were caused by STEC O55:H7. Tools developed here could assist in identification of the environmental source for these isolates, which has not yet been established.
It is common for as-prepared carbon nanotube (CNT) and graphene samples to contain remnants of the transition metals used to catalyze their growth; contamination may also leave other trace elemental ...impurities in the samples. Although a full quantification of impurities in as-prepared samples of carbon nanostructures is difficult, particularly when trace elements are intercalated or encapsulated within a protective layer of graphitic carbon, reliable information is essential for reasons such as quantifying the adulteration of physico-chemical properties of the materials and for evaluating environmental issues. Here, we introduce a microwave-based fusion method to degrade single- and double-walled CNTs and graphene nanoplatelets into a fusion flux thereby thoroughly leaching all metallic impurities. Subsequent dissolution of the fusion product in diluted hydrochloric and nitric acid allowed us to identify their trace elemental impurities using inductively coupled plasma optical emission spectrometry. Comparisons of the results from the proposed microwave-assisted fusion method against those of a more classical microwave-assisted acid digestion approach suggest complementarity between the two that ultimately could lead to a more reliable and less costly determination of trace elemental impurities in carbon nanostructured materials.
A method for the complete digestion of carbon nanostructures has been demonstrated. Photographs (on the left side) show zirconium crucibles containing SWCNTs with flux of Na2CO3 and K2CO3, before and after microwave fusion; (on the right side) the appearance of the final solutions containing dissolved samples, from microwave-assisted fusion and microwave-assisted acid digestion. These solutions were used for determining the trace elemental impurities by ICP-OES.
Display omitted
•Comparison of microwave-assisted fusion and acid digestions for carbon materials.•Full digestion of various carbon nanostructures for identical fusion conditions.•ICP-OES analysis suggests complementarity of fusion and acid digestions.
We examined the effects of LED light spectrum and alternate lighting on the proliferation of protocorm-like bodies (PLBs) and formation of shoot and root on explants of Cymbidium Sweet Waffle ...‘Tarte’in order to find the optimal lighting condition for micropropagation of the orchid. We maintained the treatments at 25±1℃ for 24 hours light period. We found that proliferation of PLBs was increased most under monochromatic green LED light (peak wavelength: 517 nm) and alternate green LED light and red LED light (peak wavelength: 631 nm). We also found that shoot formation was increased most under monochromatic red LED light and alternate green LED light and red LED light. Root formation was increased most under blue LED light (peak wavelength: 460 nm). Based on these findings, we concluded that alternate green LED light and red LED light is the optimal lighting condition, because PLB proliferation and fresh weight increase are important for micropropagation of orchids.
The aim of this work was to develop a molecular method using loop‐mediated isothermal amplification (LAMP) for detection of extended spectrum β‐lactamase (ESBL)‐producing Enterobacteriaceae from ...meat, and to compare it with different isolation agars and microarrays. LAMP assays were developed for CTX‐M groups 1, 2, and 9 and OXA‐10‐like genes. Chicken, lamb, beef, pork, and turkey samples were spiked with 10, 100, and 1,000 cfu/gram using 8 strains of ESBL‐producing Enterobacteriaceae (CTX‐M sequence types 1, 2, 3, 14, 15, OXA‐11, SHV‐2, TEM‐52) +/– a mix of competitor organisms. Samples were enriched overnight in buffered peptone water (BPW) +/– antibacterials before plating to CHROMagar CTX, OXOID ESBL Brilliance agar, and MacConkey agar with 1 mg/L cefotaxime. Selected BPW broths were also tested using LAMP assays, microarrays and using cefpodoxime discs on agar. For isolation/detection of ESBL producers from beef, pork, lamb, and turkey spiked with 10 or 100 cfu/gram ESBL (natural flora only), all agars and the LAMP assays showed 100% sensitivity and specificity for ESBL spike strains. For chicken samples, both LAMP and chromogenic agars showed improved sensitivity and specificity for isolation of ESBLs compared with MacConkey agar, particularly with competitor bacteria added. In comparison, the cefpodoxime disc method and microarray showed reduced sensitivity.
Practical application
Isolation and detection of ESBL‐producing Enterobacteriaceae from meat is an important part of monitoring for food safety as such organisms can cause disease in humans. The LAMP assays developed in this study combined with use of chromogenic agars have the potential to provide robust, rapid detection, isolation, and preliminary characterization of ESBLs in meat.
Mixed matrix membranes (MMMs) have a potential to improve the separation performance of polymeric membranes while maintaining their advantages of easy processing and lower costs. In this work, series ...of MMMs were developed via solution casting by adding porous carbon–silica nanocomposite (CSM) fillers to a readily available Matrimid® membrane. CSMs were prepared by a hard template synthesis technique to get a tuneable porosity and surface chemistry which is controlled by the optimization of the filler porosity using carbon deposition, the pyrolysis conditions, and the maximization of polarity via oxygen functional groups. SEM images of the synthesized MMMs confirmed the good adhesion and dispersion of the fillers within the polymer matrix. The separation results demonstrate that the overall separation efficiency is increased by the addition of a carbon phase, providing an increased affinity for the CO2 gas molecules next to the creation of extra porosity and free volume. It was showed that significantly improved CO2 mixed gas selectivity and permeability for CO2:N2 and CO2:CH4 gas mixtures at 9bar and 308K was achieved. For gas mixtures with a 50:50 (CO2:N2) feed composition, a 2-fold and 6-fold increase of the mixed gas selectivity (up to 42.5) and permeability (up to 27 Barrer) compared to unfilled PI was achieved, respectively. The performance of the membranes was compared to the existing literature data.
•The tuned porosity of CSM fillers using carbon and the pyrolysis conditions.•MMMs developed by embedding CSM fillers into to a polymer matrix.•Improved mixed gas separation performance for CO2:N2 and CO2:CH4 gas mixtures.
Here we describe a study examining the antibiotic resistance gene carriage in anaerobes collected during a clinical study. The results demonstrated that genes normally associated with anaerobes were ...most prevalent such as tetQ, cepA and cblA although several genes associated with Enterobacteriaceae including sul2, blaSHV and strB were also detected.
•Entropy generation on MHD peristaltic flow of boron nitride–ethylene glycol nanofluid is examined.•Rheological aspects of the nanofluid are taken into consideration.•Thermal conductivity of the ...nanofluid is assumed to vary with temperature.•Resulting nonlinear system is solved using the analytically and numerically.•Results indicate that a strong magnetic field reduces Bejan number.
This study examines the effects of entropy generation on MHD peristaltic flow of nanofluid through a non-uniform asymmetric channel by considering its rheological aspects. Thermal conductivity of the nanofluid is considered to vary with temperature. Thermophoresis, viscous heating, Brownian motion and Joule dissipation are involved in the mass species and thermal expressions. Mathematical modeling is carried out by making use of lubrication approximation. The resulting nonlinear system is solved using the Homotopy Analysis Method (HAM) which has rarely been used for such problems. Numerical results are also obtained by the Shooting method and comparison of both results is also provided. Nature of embedded constraints on momentum, thermal, concentration, Bejan number and entropy generation is reported. The presented results indicate that the strong magnetic field reduces the Bejan number. Moreover, entropy generation is less for flow through a divergent channel.
Display omitted
PDF
