Minimum Detectable Level Research Articles

Development and validation of an improved method for the detection of Salmonella in cinnamon bark and oregano leaves using the adsorbent beta zeolite in the pre-enrichment media

The detection of Salmonella in spices is challenging due to the presence of antibacterial components. In this study, we evaluated the use of an adsorbent beta zeolite in pre-enrichment media to improve the recovery of Salmonella from cinnamon bark and oregano leaves. Samples (25 g) were spiked with varying levels of S. Montevideo or S. Senftenberg. After 2 weeks of stabilization at RT, betazeolite was added to cinnamon and oregano samples prior to the addition of 225 mL or 475 mL of pre-enrichment media, respectively. Detection sensitivity and rate of the test method were compared to the FDA Bacteriological Analytical Manual (BAM) method which requires the use of 2.5 L pre-enrichment broth. While Salmonella could not be detected in the test method using the reduced volume of pre-enrichment media alone, the addition of beta zeolite resulted in a positivity rate of 62% and 72.6% for cinnamon bark and oregano leaves respectively (all spike levels and both serovars combined). Furthermore, while there were differences in the LOD50 compared to the BAM method, there was no significant difference in the minimum level of detection between the betazeolite and the BAM methods. Our results demonstrate that the use of betazeolite in the pre-enrichment media offers a method with reduced media volumes without compromising on the sensitivity or efficiency of Salmonella detection in cinnamon bark and oregano leaves.

Contamination of Slovak Bilberry (Vaccinium Myrtillus L.) with Radiocaesium 137Cs in Selected Slovak Locations

Abstract The aim of this study was to determine the activity of post-Chernobyl 137Cs in Slovak bilberry (Vaccinium myrtillus L.) from selected locations of Slovakia depending upon: the season, location and the soil-plant transfer factor (TF). The 137Cs activity was determined in samples of forest soil and bilberry bushes (stems, leaves and fruits) growing on the soil in three locations: Arboretum Mlyňany (1), Hodruša-Hámre (2) and Javorníky (3). Altogether we collected 35 samples; namely 15 samples from Arboretum Mlyňany, 10 samples from Hodruša-Hámre and 10 from Javorníky. The samples of soil were examined also for the activity of 40K. The samples were collected in the spring, summer and autumn in the years 2019 and 2020 and were analysed by a gamma-ray spectrometry method. The highest levels of 137Cs activity concentrations were determined in Hodruša-Hámre in September where they reached 161 ± 13 Bq.kg−1 in the soil, 3.95 ± 1.07 Bq.kg−1 in the stems and 14.7 ± 4.26 Bq.kg−1 in the leaves. The lowest levels were determined in the Arboretum Mlyňany in October where the 137Cs activity in the soil reached 13.1 ± 1 15 Bq.kg−1, while in the stems, leaves and fruits it was lower than the minimum detectable level. In the latter location, we also determined the highest activity of 40K, the radioactive isotope physiologically and metabolically similar to 137Cs. The mass activity of 137Cs in all samples of bilberries were lower than the minimum detectable activity (MDA). The comparison of the results obtained in this study with the limit for total mass activity of radiocaesium (134Cs + 137Cs) in the food (600 Bq.kg−1) allowed us to conclude that the fruits, stems and leaves of Slovak bil-berries present neither health nor environmental risk.

Absence of Detectable Radionuclides in Breast Milk in Sendai, Japan in 2012 Even by High-Sensitivity Determination: Estimated Dose among Infants after the Fukushima Nuclear Disaster.

The aim of this study was to estimate radionuclide levels in breast milk and the transferred dose to their infants in Sendai (100 km from Fukushima), Japan after the 2011 Fukushima nuclear disaster. Radionuclide concentrations were analyzed in 101 specimens of breast milk collected in 2012. Median values for minimum detectable activities were 0.39, 0.34, 1.1, 1.89, and 17.1 Bq/kg for 137Cs, 134Cs, 131I, 110mAg, and 40K, respectively. Only radionuclides from 40K were detected. To estimate potential exposure and radiocesium dose, we assumed that the samples contained each minimum detectable activity level. The mean minimum detectable activity concentrations (standard deviation) of 137Cs and 134Cs were 0.42 (0.15) and 0.37 (0.14) Bq/kg, respectively. Means of estimated dietary intakes of 137Cs and 134Cs among infants were 0.35 (0.12) and 0.31 (0.11) Bq/day, respectively. The committed effective doses of radiocesium in infants aged 3 and 12 months via breastmilk were estimated at 5.6 (2.1) and 3.3 (1.2) μSv/year, respectively. Dietary intakes of 137Cs and 134Cs in breastfeeding mothers were back-calculated at 1.9 (0.71) and 1.7 (0.65) Bq/day, respectively. The study verified no discernible exposure to radionuclides among infants. The most conservative estimates were below the Japanese internal exposure limit of 1 mSv/year.

Measurement of radon exhalation rate from building materials: The case of Highland Region of Ecuador

Exposure to 222-Radon (Rn) usually occurs in closed environments as effect of the Rn exhaled from building materials, soil or water. While building materials provide a protection barrier to outdoor natural radiation (terrestrial and cosmic), their radionuclide composition could increase the indoor Rn exposure. In fact, the Rn exhalation of building materials is of great importance from the viewpoint of mitigation and public health in very specific conditions. This work presents the Rn exhalation rates of 40 building materials (concrete blocks, clay brick, granite and concrete samples) produced and used in Ecuador, as well as the effective dose for a reference dwelling. Rn concentration measurements were performed using the closed chamber method and a RAD7 equipment. The resulting Rn exhalation rates were found to be in the range from 0 to 7.83 Bq·m-2·h-1. The highest surface exhalation rate was detected in granite samples, while clay bricks show Rn exhalation below the minimum detection level (0.05Bq·m-2·h-1). In the reference dwelling, the effective dose rates caused by Rn exhalation from building material range from 0.019 up to 0.112 mSv/y. However, the effective dose rate depends on the exposure time and quantity of granite used. Our results could be of immediate help to choose suitable building materials to ensure a safe indoor environment for the dwellers.

Development of antigen sandwich ELISA to detect interferon-alpha (IFN-α) using monoclonal antibodies in chicken

Abstract Interferon alpha (IFN-α) belongs to the type I interferon family which mediates an early innate immune response to viral infections. In the present study, we developed a sandwich ELISA using specific mouse monoclonal antibodies (mAbs) to measure IFN-α production in chickens. Recombinant chicken IFN-α (chIFN-α) expressed in yeast was used to immunize the mice. Five mAbs which specifically recognize chIFN-α antigen were selected and characterized. For sandwich ELISA development, mAbs were labeled with biotin, followed by a pairing assay to identify the best capture and detection antibodies. Two sets of mouse anti-chIFN-α mAb pairs were identified as optimum pairs of antibodies for detection of chIFN-α. The sandwich ELISA effectively detected native chicken IFN-α in chicken macrophage cells stimulated by polyinosinic:polycytidylic acid and its minimum detectable level was about 25 pg/mL. The anti-viral activity of chIFN-α against vesicular stomatitis virus (VSV) was evaluated in chicken embryonic fibroblast and the mouse anti-chIFN-α mAbs which neutralize the activity of chicken IFN-α against VSV were identified. The newly developed antigen capture sandwich ELISA for the detection of chIFN-α will be a useful tool to monitor IFN-α production in chickens during viral infections.

Simultaneous electrochemical determination of nitrophenol isomers Based on spirofluorene - based microporous polymer film modified electrodes through one-step electropolymerization strategy

A novel, convenient, and highly selective electrochemical sensor for simultaneous determination of nitrobenzene isomers based on conjugate microporous polyspirofluorene film modified glassy carbon electrodes (PSF/GCE) was established in this work, which was conducted on GCE through one-step co-electropolymerization for the first time. The proposed strategy exhibited outstanding electrocatalytic activity for the reduction of nitrophenol. Well identifiable redox peaks for each nitrobenzene isomer were obtained and their simultaneous detection can be received due to the high content of π - π orbital of spirofluorene - based conjugated microporous polymer film, which abundant electron significantly enhances the electrochemical response with electron-poor nitro-analytes. Related characterizations have confirmed its excellent electroactive surface area and analytical properties of the as-prepared sensor. Under the optimization conditions, the linear range of the sensor is from 0.1–100 μM for o-nitrophenol, 0.2–100 μM m-nitrophenol, and 0.1–120 μM for p-nitrophenol, while their minimal detection levels were 0.01 μM, 0.03 μM, and 0.01 μM, respectively. The modified electrode also revealed high selectivity, good reproducibility, and promising stability. More importantly, satisfactory recoveries were received for the developed sensor in the detection of target nitrophenol isomers, which exhibited a broad prospect in practical application.

Manufacturing lateral flow tests for tuberculosis diagnosis: choosing a reactants completion and sensing regime

To develop technologies for rapid out-of-laboratory diagnoses of tuberculosis based on the level of specific antibodies, the requirements for the antibody preparations and their combinations used in the analysis were studied, as well as procedures for the manufacture of a multimembrane composite. A comparative characterization of various recombinant antigens in terms of diagnostic sensitivity and specificity was carried out. The possibility of increasing the diagnostic sensitivity to 15%–20% when using multi-antigen mixtures (cocktails) of antigens was shown. The requirements for the manufacture of multi-membrane composites—test strips for diagnostics—were determined. The correspondence of the minimum detectable level of specific antibodies to the diagnostic threshold of 0.2 mg/ml was shown. Testing of test systems via the most effective cocktails of antigens on blood samples from healthy and sick subjects was carried out.

Wideband fiber-optic Fabry-Perot acoustic sensing scheme using high-speed absolute cavity length demodulation.

In this paper, we realize a wideband fiber-optic Fabry-Perot (F-P) acoustic sensing (FPAS) scheme by utilizing a high-speed absolute cavity length demodulation with a 70-kHz maximum line rate spectrometer. The wideband FPAS is made of a pre-stress stainless-steel diaphragm based on F-P interferometric structure. The real-time absolute F-P cavity lengths are calculated by a phase demodulation method, which is realized by processing the interference image at a 70-kHz frame rate. Acoustic signal is obtained by extracting the AC component of the demodulated cavity length. The experimental results show that the spectrometer can be running at a 50-kHz line rate, and an acoustic detection wideband of 20 Hz to 20 kHz is obtained. The noise-limited minimum detectable sound pressure level is 18.8 dB, which is sensitive enough for the communication of human voice. The proposed wideband acoustic sensing scheme achieves good robustness, which is promising as a speech-sound microphone for communication during the magnetic resonance imaging procedure.

Individual Monitoring of Internal Exposure for Nuclear Medicine Workers in NINMAS through In-Vitro Bioassay Techniques

Internal radiation monitoring of occupational radiation workers is essential for protecting them against the risks of incorporated radionuclides. More than 400 workers in Bangladesh are working with unsealed radioactive sources and most of them are employed at different nuclear facilities. Among the 18 Nuclear Medicine Centers in the country, the National Institute of Nuclear Medicine and Allied Science (NINMAS), Dhaka was selected for this study where workers get internal radiation exposure while processing and labeling of the liquid sources. The aim of this study was to estimate the activity concentration and committed effective doses from bioassay sample, namely urine samples of Nuclear Medicine (NM) workers due to handling of radioactive Iodine (131I), Technetium (99mTc) and Fluorine (F-18). Total 86 urine samples were collected from 17 occupational workers of NINMAS during the year 2017 and analyzed using High Purity Germanium (HPGe) detector. The radioactivity of 131I and (99mTc) was found 2.21±0.44 BqL-1 to 444 ± 39.91 BqL-1 and 5.53±1.12 BqL-1 to 603 ± 72.36 BqL-1 respectively. Due to low activity of the unsealed F-18 sources and for appropriate shielding, radioactivity of F-18 was found below the minimum detection level in the urine samples of the workers who handled it. The effective doses of occupational workers have also been calculated using the radioactivity concentration and the dose coefficients given in ICRP publication 78. The highest and lowest effective doses due to handling of the unsealed source of (99mTc) were 28.2 and 0.0258μSv for working with 780 and 36mCi of radionuclide respectively. On the other hand, the highest and lowest effective doses due to handling of 131I were 8.73and 0.045μSv, for working with 1425 and 55 mCi respectively. Both the doses are found to comply with ICRP annual dose limit of 20 mSv.
 Bangladesh J. Nuclear Med. 22(2): 125-129, Jul 2019

Optimized and validated protocol to the detection of the invasive bivalve Limnoperna fortunei from eDNA plankton samples

Abstract: We optimized a methodology for plankton environmental DNA detection of the invasive golden mussel and validated it in samples from a Southern Brazil reservoir. Limnoperna fortunei is a successful invasive alien species that causes significant impacts on freshwater ecosystems. We adjusted and validated the methodology to detect L. fortunei in plankton samples, with a SYBR Green assay. Based on the standard curve analysis, the observed theoretical minimal qPCR detection level was 0.0005625 ng.µL-1 (R2 = 0.99) at a PCR quantification cycle of 14.09–29.56. We also presented a practical guide to be used in monitoring and detection of L. fortunei. The optimized protocol was efficient in detecting L. fortunei and can be used to monitor already infested environments or invasions in new environments.

Bioinspired Gradient Conductivity and Stiffness for Ultrasensitive Electronic Skins.

Hierarchical and gradient structures in biological systems with special mechanical properties have inspired innovations in materials design for construction and mechanical applications. Analogous to the control of stress transfer in gradient mechanical structures, the control of electron transfer in gradient electrical structures should enable the development of high-performance electronics. This paper demonstrates a high performance electronic skin (e-skin) via the simultaneous control of tactile stress transfer to an active sensing area and the corresponding electrical current through the gradient structures. The flexible e-skin sensor has extraordinarily high piezoresistive sensitivity at low power and linearity over a broad pressure range based on the conductivity-gradient multilayer on the stiffness-gradient interlocked microdome geometry. While stiffness-gradient interlocked microdome structures allow the efficient transfer and localization of applied stress to the sensing area, the multilayered structure with gradient conductivity enables the efficient regulation of piezoresistance in response to applied pressure by gradual activation of current pathways from outer to inner layers, resulting in a pressure sensitivity of 3.8 × 105 kPa-1 with linear response over a wide range of up to 100 kPa. In addition, the sensor indicated a rapid response time of 0.016 ms, a low minimum detectable pressure level of 0.025 Pa, a low operating voltage (100 μV), and high durability during 8000 repetitive cycles of pressure application (80 kPa). The high performance of the e-skin sensor enables acoustic wave detection, differentiation of gas characterized by different densities, subtle tactile manipulation of objects, and real-time monitoring of pulse pressure waveform.

Dual Enhanced Fiber-Optic Microphone Using Sensitive Diaphragm-Free Transducer and Ultrahigh-Resolution Spectral Demodulation

Interferometric fiber-optic microphones (FOMs) with outstanding sensitivity are ideal method to detect weak acoustic signals. In this work, we demonstrated an ultrasensitive fiber-optic Michelson microphone with dual enhancement by using a diaphragm-free acoustic transducer and a high-resolution optical path difference (OPD) demodulation device. A cylindrical polyvinyl chloride (PVC) tube wrapped around by the optical fiber was employed as a transducer to enhance the responsivity to weak acoustic wave. A high-resolution spectrum demodulation-based white-light interferometer (WLI) was utilized to measure the variations of OPD. In theory, the FOM owns features to overcome defects of the conventional diaphragm-based or intensity demodulation method-based FOMs, such as quadrated point (Q-point) drifting and being sensitive to environmental interference. Experimental results showed that this FOM had an ultrahigh sensitivity of ~6800 nm/Pa at the resonance frequency of 1455 Hz. The sensitivity and the noise-limited minimum detectable sound pressure level (MDSPL) at 1000 Hz were calculated to be 315.3 nm/Pa and - 20.4 dB/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> (1.9μ Pa/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> ), respectively.

Development of antigen sandwich ELISA to detect interferon-alpha (IFN-α) using monoclonal antibodies in chicken

Interferon alpha (IFN-α) belongs to the type I interferon family which mediates an early innate immune response to viral infections. In the present study, we developed sandwich ELISA using specific mouse monoclonal antibodies (mAbs) to measure IFN-α production in chickens. Recombinant chicken IFN-α (chIFN-α) expressed in yeast were purchased from Kingfisher Biotech, and used to immunize the mice. Five mAbs which specifically recognize chicken IFN-α antigen were selected and characterized. For sandwich ELISA development, mAbs were labeled with biotin, followed by a pairing test to identify the best capture and detection antibodies. Two sets of mouse anti-chIFN-α mAb pairs were determined and a standard curve was established using recombinant chIFN-α. The sandwich ELISA effectively detected an increased IFN-α production in chicken macrophage cells stimulated by polyinosinic:polycytidylic acid (poly I:C), and its minimum detectable level was about 25 pg/mL. The anti-viral activity of chIFN-α against vesicular stomatitis virus was characterized in avian embryonic fibroblast and the mouse anti-chIFN-α mAbs which neutralize its activity were identified. The newly developed antigen sandwich ELISA developed in this study will be a useful tool to monitor IFN-α production in chickens.

Evaluating environmental DNA as a tool for detecting an amphibian pathogen using an optimized extraction method.

Environmental DNA (eDNA) detection is a valuable conservation tool that can be used to identify and monitor imperiled or invasive species and wildlife pathogens. Batrachochytrium pathogens are of global conservation concern because they are a leading cause of amphibian decline. While eDNA techniques have been used to detect Batrachochytrium DNA in the environment, a systematic comparison of extraction methods across environmental samples is lacking. In this study, we first compared eDNA extraction methods and found that a soil extraction kit (Qiagen PowerSoil) was the most effective for detecting Batrachochytrium dendrobatidis in water samples. The PowerSoil extraction had a minimum detection level of 100 zoospores and had a two- to four-fold higher detection probability than other commonly used extraction methods (e.g., QIAamp extraction, DNeasy+Qiashredder extraction method, respectively). Next, we used this extraction method on field-collected water and sediment samples and were able to detect pathogen DNA in both. While field-collected water filters were equivalent to amphibian skin swab samples in detecting the presence of pathogen DNA, the seasonal patterns in pathogen quantity were different between skin swabs and water samples. Detection rate was lowest in sediment samples. We also found that detection probability increases with the volume of water filtered. Our results indicate that water filter eDNA samples can be accurate in detecting pathogen presence at the habitat scale but their utility for quantifying pathogen loads in the environment appears limited. We suggest that eDNA techniques be used for early warning detection to guide animal sampling efforts.

Study of gross alpha, gross beta and natural radioactivity in soil samples of district Muzaffarabad

ABSTRACT Results for the specific activities of primordial radionuclides, gross alpha and gross beta activities in soil samples collected from 29 locations of Azad Kashmir are presented. Soil samples were analysed, for possible radionuclide contents and relevant health implications, by high-resolution γ-ray spectroscopy and α/β counter ASC-950-DP Protean instrument. The alpha activity varied from 77.31 ± 9.95 to 440.08 ± 16.48 Bq kg-1 with overall average value of 234.88 ± 1.69 Bq kg-1. While beta activity varied from the minimum detection level, i.e., <MDL to 361.55±149.33 Bq kg-1, with average value for all samples estimated as 235.65 ± 149.98 Bq kg-1. Specific activities of 232Th, 226Ra and 40K were calculated using γ-ray spectroscopy and were subsequently utilised for the estimation of radiation doses and radiological hazards. Activity concentrations due to 40K, 232Th and 226Ra were found in the ranges 213.54 ± 17.22 to 1205.83 ± 12.82, 26.11 ± 3.72 to 84.70 ± 4.63 and 13.74 ± 1.46 to 62.23 ± 4.29 Bq m-3, with average values 616.22 ± 29.20, 55.83 ± 5.74 and 37.91 ± 2.35 Bq m-3 respectively, whilst, activity concentration due to anthropogenic radionuclide 137Cs was found in the range from minimum detection limit, i.e., ≤0.50 to 8.82 ± 0.83 Bq m-3. Average value for 137Cs sample was found as 3.43 ± 0.28 Bq m-3. Excess lifetime cancer risk (ELCR) for indoor occupation varied from 4.94 × 10-4 to 1.82 × 10-3 and for outdoor occupation 1.32 × 10-4 to 4.62 × 10-4. Overall excess lifetime cancer risk (ELCR) for the current study was estimated as 1.55 × 10-3. The average values of radionuclide, in presently investigated soil samples, were within the worldwide range (50 Bq Kg-1) for radium radionuclide contents whilst higher for thorium and potassium radionuclides contents. Current study results can serve as baseline data for any nuclear emergency in future and may be helpful in setting radiological map of country and devising nuclear regulatory standards for background radiations in country.

Geomorphological impacts of a glacier lake outburst flood in the high arctic Zackenberg River, NE Greenland

Glacier lake outburst floods (GLOFs), especially those in the Arctic, can deliver exceptionally high volumes of sediment and solutes to fjords and shallow-marine settings, in comparison to typical seasonal river flows. These sediments and solutes strongly affect coastal geomorphology and aquatic ecosystems, yet are rarely observed. In this study, we have quantified the short-term geomorphological response of the most distal part of the Zackenberg River (northeast Greenland), where it enters Young Sund, to a glacier lake outburst flood that occurred on August 6th 2017. The main aims were to: (1) quantify riverbank and floodplain geomorphology changes that occurred as a consequence of the flood; (2) analyse the spatial patterns of those geomorphological changes and suggest the key controls on them. We used a time-series of very high-resolution UAV-generated images taken on the 5th, 6th, and 8th of August 2017, which enabled us to compare pre- and post-flood fluvial geomorphology. The GLOF induced intense and widespread geomorphological changes, which was surprising because several floods of a similar magnitude have occurred along this river. Approximately 30% of the area of interest experienced changes that were larger than the minimum level of detection (0.15 m). Lateral erosion reached almost 10 m in some places. The total volume loss from bank erosion was at least 26,561 m3 (+/− 14%), whereas the deposition was at least 7745 m3 (+/− 39%). Such an intensive geomorphological response resulted from a combination of factors; namely: (1) bank geometry; (2) composition of bank material; (3) time of occurrence of the event; (4) presence of permafrost; (6) channel geometry; and (7) multitude and diversity of geomorphological processes. We speculate the severity of the geomorphological impact relative to that from previous floods could have been due to warming air temperatures that provided sediment from thawed permafrost, and to an aggrading delta that raised the river base level. Overall, we contend that climate warming will not only make outburst floods from glaciers more likely but that those floods will achieve more geomorphological work with mechanical erosion of permafrost. Erosion and gravitational failures during future flood events will perhaps become even more widespread and intense.

Polymerase chain reaction for the detection of histamine-producing bacteria isolated from Taiwanese foods

It is important to develop rapid methods to detect the presence of histamine producers. In this study, the polymerase chain reaction (PCR) assay yielded a 367-bp DNA amplification fragment from histidine decarboxylase (hdc) of gram-positive bacteria using JV16HC/JV17HC primer, and 534-bp and 709-bp DNA amplification fragments from histidine decarboxylase of gram-negative bacteria using 106/107 and hdc-f/hdc-r primers, respectively. Seven gram-positive histamine-producing strains and 15 gram-negative histamine-producing strains isolated from Taiwanese foods successfully produced the PCR amplification products. The minimum levels of detection of Enterobacter aerogenes or Raoultella ornithinolytica after the PCR amplification using hdc-f/hdc-r and 106/107 primers were 105 and 106 CFU/mL in TSB broth, and 106 and 107 CFU/g in marlin homogenates, respectively. The hdc amplification using hdc-f/hdc-r primer was detected 2 h earlier than the HPLC detection of histamine in TSBH broth or marlin homogenates inoculated E. aerogenes or R. ornithinolytica. However, the detection of hdc amplification using the 106/107 primer and that of histamine by HPLC occurred at the same sampling time. Therefore, the PCR method could be easily used to detect potential histamine-producing bacteria in foods.

Accuracy and precision of McMaster and Mini-FLOTAC egg counting techniques using egg-spiked faeces of chickens and two different flotation fluids

Faecal egg counting techniques (ECTs) are useful tools for assessing anthelmintic efficacy and selecting hosts resistant to parasite infection. McMaster (MM) is one of the most commonly used ECTs, but it suffers from low sensitivity and precision. Mini-FLOTAC (MF) has been proposed to replace MM, but so far has not been evaluated for gastro-intestinal nematode infections in chickens. This study compared sensitivity, precision, and accuracy of MM and MF with two trials using egg-spiked faecal samples ranging from 50–1250 eggs per gram of faeces (EPG). In addition, effects of two flotation fluids with different specific gravities (SG), namely salt (SG = 1.20) and sucrose solutions (SG = 1.32), on accuracy and time-spent for both ECTs were evaluated.Overall sensitivity based on the composite reads across all EPG-levels was 97.1 % for MM and 100 % for MF. MF was, however, more sensitive (P = 0.003) or tended to (P = 0.087) be more sensitive than MM at only the lowest EPG-level (i.e. 50 EPG) using one of the duplicate reads, whereas there was no significant difference at any EPG-level using composite reads. Overall average precision of MF (79.5 %) was higher (P < 0.001) than that of MM (63.4 %) across all EPG-levels. Precision of MM increased from 22 to 87 % with increasing EPG-levels from 50–1250 EPG. Corresponding precision estimates for MF ranged from 76 to 91 %. Overall recovery rate of MM (74.6 %) was significantly higher (P < 0.001) than that of MF (60.1 %). There was no significant difference in recovery rate of spiked-eggs among different EPG-levels (P = 0.833). Recovery rate of MM ranged from 64 % to 79 % across different EPG-levels, while it ranged from 54 % to 64 % with MF without an interaction between ECT and EPG-level (P = 0.701). It took more time (P < 0.001) to process (prepare and read) samples with MF than with MM using the same flotation fluid. The sugar solution tended to (P = 0.100) increase egg-recovery with both ECTs, while increasing (P < 0.001) time-spent for processing the samples.Our data collectively suggest that MM is less sensitive than MF only at around minimum detection level of MM when using unrepeated reads. We conclude that McMaster is faster, relatively more accurate but less precise than Mini-FLOTAC. The sugar solution with higher SG increases accuracy of both techniques at the expense of increased labour time.

Design of a multiplex quantitative reverse transcription-PCR system to simultaneously detect 16 pathogens associated with bovine respiratory and enteric diseases.

Bovine respiratory disease (BRD) and bovine enteric disease (BED) are two major diseases in cattle, resulting in severe economic losses in the dairy and beef industries. The two major diseases are associated with several factors such as viruses, bacteria, the health condition of the host and environmental factors. We aimed to design a new efficient diagnostic method, which rapidly detect causative pathogens, minimizing economic loss due to BRD and BED. We designed a multiplex quantitative reverse transcription-PCR (qRT-PCR) system for the simultaneous diagnosis of 16 pathogens, including 12 viruses and 4 bacteria related to BRD and BED, based on single qRT-PCR assays in previous studies. The designed multiplex qRT-PCR was highly sensitive and has minimal detection levels which will be no different from those of single qRT-PCR. Moreover, the multiplex qRT-PCR could more efficiently detect the causative pathogens than conventional RT-PCR in test using a part of BRD and BED clinical samples. Furthermore, our data revealed that the multiplex qRT-PCR had high performance in its specificity and reproducibility tests. Our system can effectively detect multiple BRD or BED related pathogens from each animal while testing several clinical samples via the multiplex qRT-PCR. It is more time-, cost- and labour-efficient than other diagnostic methods. Rapid detection of infected animals from the herd using our system will greatly contribute to infection control and prompt treatment in field.

Fluorination of shape-controlled porous carbon nanoweb layers for ammonia gas sensor applications

Fluorinated porous carbon nanoweb layers (FPCNWLs) are simply fabricated by spin coating of adjusting polymer mixing ratio, sequential thermal treatments, and vacuum plasma treatment to enhance the specific surface area and to dope the fluorine into the carbon lattice. The different surface tension, polarity, and molecular weight of PAN and PS causes immiscible solution, therefore, the various size of pores on the carbon structure are constructed during the stepwise thermal treatment. Moreover, the F doping ratio is easily controlled with different plasma treating time. The fluorination causes both p-type doping and affinity toward ammonia gas. The fabricated FPCNWLs-based ammonia gas sensor devices demonstrate outstanding NH3 gas sensing performances that minimum detection level (MDL) of FPCNWLs-based ammonia gas sensor is 9 ppb using FPCNWL20 and the sensors display linear range from 9 ppb to 90 ppm. In conclusion, the FPCNWL20-based ammonia gas sensor demonstrates rapid response and recovery time, excellent cyclic stability, reusability, durability, and selectivity.