Minimum Detectable Level Research Articles

Measuring Ciliary Neurotrophic Factor (CNTF) in Lacrimal Fluid Using Optimized Commercial ELISA

The concentration of ciliary neurotrophic factor (CNTF) was measured in lacrimal fluid (LF) using Human CNTF Quantikine ELISA kit (“R&D Systems”, USA) on a ChemWell 2910 automatic analyzer (“Awareness Technology Inc.”, USA). We initially attempted to use commercial kits, designed for serum and plasma CNTF detection, to quantify lacrimal CNTF. The results, however, were rarely above the minimum detection level of the kits, most likely due to matrix complexity and low concentrations of CNTF in diluted LF (LF had to be diluted because of the small volume of collected samples). The optimal sensitivity and the lowest background for the best minimum quantifiable value were determined empirically. Phosphate buffer solution containing 1% bovine serum albumin was selected as an optimal diluent for CNTF measurements in small fluid samples. A standard curve was produced using the calibrating solutions 0-250 pg/ml. Acid treatment of LF samples before the analysis allowed to increase the detectable concentration of the CNTF two-fold. The 1:3 dilution was selected based on the available volume of collected LF and a reasonable variation coefficient. The described protocol allowed to develop a sandwich ELISA optimized for lacrimal CNTF.

Increased Cervical Human Immunodeficiency Virus (HIV) RNA Shedding Among HIV-Infected Women Randomized to Loop Electrosurgical Excision Procedure Compared to Cryotherapy for Cervical Intraepithelial Neoplasia 2/3.

Treatment of human immunodeficiency virus (HIV)-infected women to prevent cervical cancer may stimulate HIV RNA cervical shedding and risk HIV transmission. From 2011 to 2014, 400 HIV-infected women diagnosed with cervical intraepithelial neoplasia 2/3 in Kenya were randomized to loop electrosurgical excision procedure (LEEP) or cryotherapy. Cervical samples were collected at baseline and 3 weekly intervals. Samples were tested for HIV RNA using the Gen-Probe Aptima HIV assay with a minimum detection level of 60 copies/swab and analyzed using generalized estimating equations. Women who received LEEP had significantly higher cervical HIV RNA levels than those who received cryotherapy at weeks 2 (adjusted incident rate ratio [aIRR], 1.07; P = .038) and 3 (aIRR, 1.08; P = .046). Within LEEP, significantly higher cervical shedding was found at weeks 2 (2.03 log10 copies/swab; P < .001) and 3 (2.04 log10 copies/swab; P < .001) compared to baseline (1.80 log10 copies/swab). Cervical HIV RNA was significantly higher following LEEP for up to 3 weeks among women on antiretroviral treatment (ART) (0.18 log10 copies/swab increase; P = .003) and in ART-naive women (1.13 log10 copies/swab increase; P < .001) compared to baseline. Within cryotherapy, cervical shedding increased in ART-naive women (0.72 log10 copies/swab increase; P = 0.004) but did not increase in women on ART. Women randomized to LEEP had a larger increase in post-procedural cervical HIV shedding than cryotherapy. Benefits of cervical cancer prevention outweigh the risk of HIV sexual transmission; our findings underscore the importance of risk-reduction counseling. NCT01298596.

In-vitro and in-vivo measurement of the animal's middle ear acoustical response by partially implantable fiber-optic sensing system

The main obstacle in realization of a totally implantable hearing aid is a lack of reliable implantable microphone. In this paper we have described a potentially miniature fiber-optic vibrometer based on a modified Michelson interferometer, designed to serve as a middle-ear microphone for totally implantable cochlear- or middle-ear hearing aids. A model of the sensing system was used for in-vitro and in-vivo investigation of acoustical response of sheep's middle-ear ossicles. Surgical and implantation procedure of introducing the sensing optical fiber into the middle-ear and its aiming at the incus was investigated and described here in detail. The frequency responses of the incus was measured while a cadaver and living sheep was exposed to the sinusoidal acoustical excitation of 40–90dB SPL, in the frequency range from 100Hz to 10kHz. The amplitude of the incus vibration was found to be in the range between 10pm to 100nm, strongly depending on the frequency, with a lot of resonant peaks, corresponding mainly to the natural outer ear canal gain. The noise floor in the experiments was about 2pm/Hz1/2, but recently we have decreased it to < 0.5pm/Hz1/2, which corresponds to a minimal detectable sound level of 31–35dB(A) SPL for humans. The histological examination of temporal bones of cadaver animals and the intensity of in-vivo optical signal demonstrated that the aiming of the sensing fiber to the target has been preserved for five months after the implantation.

Enhanced sensitivity and responses to viologens from a whole-cell bacterial bioreporter treated with branched polyethyleneimines.

Evaluate the use of polyethyleneimines (PEIs) as membrane permeabilizers to improve the responses and sensitivity of a bacterial bioreporter strain to viologens. The responses from E.coli str. EBS, i.e., E.coli BW25113 carrying plasmid pSDS, when exposed to five different viologens were characterized, as were the toxicities of seven different PEIS, including two linear and five branched species. Based on these results, benzyl viologen led to the greatest responses, and 0·8-kDa branched PEI (BPEI) was the least toxic of the PEIs tested and, therefore, both were selected for the subsequent tests. The bioluminescence and relative responses from E.coli str. EBS exposed to various concentrations of 0·8kDa BPEI identified 400mgl-1 as the optimal concentration. Using this concentration, tests were performed with all five of the viologens. The responses from E.coli str. EBS to the viologens were improved, with the maximum relative bioluminescence values increasing between 5·6 and 16·5-fold. The minimum detectable levels for four of the viologens were likewise improved 2- to 4-fold. Improving bacterial membrane permeability in a controlled manner using BPEIs can improve biosensing of toxic compounds, as well as be used in biofuel and bioenergy applications where membrane permeability to a solute is important.

Polarimetric Analysis of the Long Duration Gamma-Ray Burst GRB 160530A With the Balloon Borne Compton Spectrometer and Imager

Abstract A long duration gamma-ray burst, GRB 160530A, was detected by the Compton Spectrometer and Imager (COSI) during the 2016 COSI Super Pressure Balloon campaign. As a Compton telescope, COSI is inherently sensitive to the polarization of gamma-ray sources in the energy range 0.2–5.0 MeV. We measured the polarization of GRB 160530A using (1) a standard method (SM) based on fitting the distribution of azimuthal scattering angles with a modulation curve and (2) an unbinned, maximum likelihood method (MLM). In both cases, the measured polarization level was below the 99% confidence minimum detectable polarization levels of 72.3% ± 0.8% (SM) and 57.5% ± 0.8% (MLM). Therefore, COSI did not detect polarized gamma-ray emission from this burst. Our most constraining 90% confidence upper limit on the polarization level was 46% (MLM).

A novel LC-MS/MS method for the quantitative measurement of the acetate content in pharmaceutical peptides

Most pharmaceutical peptides are supplied as acetate salts and the relative amount of acetate to peptide in the final product is one quality criterion required by regulatory agencies to approve the product for clinical use. The objective of the present study was to develop a validated LC-MS/MS method that allows the quantitative determination of the acetate content in pharmaceutical peptide preparations and simultaneous monitoring and collection of qualitative and quantitative information on the peptide during manufacture and in the final product. The method uses reversed phase C18-chromatography to elute the acetate ions under acidic conditions, pH 3, followed by post-column infusion of ammonium hydroxide 0.6M, methanolic solution (30:70) at a rate of 0.5mL/hr. The acetate ions were monitored in negative polarity mass spectrometry by pseudo multiple reaction monitoring (pseudo MRM) against 1, 2- 13C labelled acetate, the internal standard used in the method. The method was linear for acetate concentrations between 0.4 and 25μg/mL with a coefficient of determination (r2) equal to 0.9999. The minimum level of detection and minimum level of quantification were at 0.06μg/mL and 0.18μg/mL respectively. Accuracy of the method was judged by determining the acetate content in a commercial product of the peptide pharmaceutical tetracosactide (TCS) and parallel comparison to the amounts determined by a reversed phase HPLC method with detection at a wavelength of 210nm. The amounts determined by the two methods were in agreement with a RSD that was less than 2%. Additional confirmation of method accuracy was determined by spiking the pharmaceutical peptide with varying amounts of acetate. The recoveries ranged on average between 101 and 102% for the spiked amounts. Accuracy was also determined by calculating the percentage relative error of the predicted to actual acetate concentration in quality controls and was determined to be less than 5%. The LC-MS/MS method was precise with an intra- and inter-day RSD of less than 5%. The standard solutions were stable for at least one month when kept frozen at −80°C with no loss in response and an inter-day RSD of less than 5%. The method was applied to quantify the acetate content in the clinically available product of TCS and to simultaneously evaluate the average peptide molecular weight and detect known impurities by switching from negative polarity MRM analysis to positive polarity MS analysis following the elution of the acetate peak. The method reported herein should corroborate quantitative determinations of the acetate content in pharmaceuticals by the traditional compendial HPLC method.

Correlation electron cyclotron emission diagnostic in TCV.

The correlation electron cyclotron emission diagnostic of tokamak à configuration variable has recently been upgraded. It now has the choice of three lines of sight: two horizontal lines placed on the low field side of the vessel, perpendicular to the magnetic field, and a dual-axis steerable antenna. The polarization of the radiation collected by the latter can be rotated using a universal polarizer situated in the transmission line. This line is also shared with a reflectometry system, allowing simultaneous measurements of temperature and density fluctuations in the same plasma volumes. When using this line, it is possible to choose between two dedicated front ends characterized by different local oscillator frequencies, adding flexibility in the choice of the plasma region to be studied. The intermediate frequency section is now equipped with six frequency tunable YIG filters allowing the study of turbulence properties in a wide range of radial positions. When studying fluctuations over the whole video bandwidth, the minimum detectable fluctuation level is δTe/Te∼0.5%. The new system has been used to measure electron temperature fluctuations over a large fraction of the plasma profiles in a series of plasmas with triangularity varying from 0.6 to -0.6 but comparable collisionality profiles.

Super high sensitive plate acoustic wave humidity sensor based on graphene oxide film

The changes of density and elastic modules due to water vapor adsorption are measured for graphene oxide film at room temperature. Dominant mechanism for acoustic wave humidity sensing by the film is shown to be related with variation of its electric conductivity. Basing on the data, super high sensitive humidity sensor employing high-order Lamb wave with large coupling constant, standard lithium niobate plate, and graphene oxide sorbent film is developed. The minimal detectable level of the sensor is as low 0.03% RH, response times are 60/120s, and reproducibility is ±2.5%. The sensor is completely selective towards H2, CO, CH4, NO, O2.

DMSO Assisted Electrospray Ionization for the Detection of Small Peptide Hormones in Urine by Dilute-and-Shoot-Liquid-Chromatography-High Resolution Mass Spectrometry

The mobile phase additive (DMSO) has been described as a useful tool to enhance electrospray ionization (ESI) of peptides and proteins. So far, this technique has mainly been used in proteomic/peptide research, and its applicability in a routine clinical laboratory setting (i.e., doping control analysis) has not been described yet. This work provides a simple, easy to implement screening method for the detection of doping relevant small peptides (GHRPs, GnRHs, GHS, and vasopressin-analogues) with molecular weight less than 2 kDa applying DMSO in the mobile phase. The gain in sensitivity was sufficient to inject the urine samples after a 2-fold dilution step omitting a time consuming sample preparation. The employed analytical procedure was validated for the qualitative determination of 36 compounds, including 13 metabolites. The detection limits (LODs) ranged between 50 and 1000 pg/mL and were compliant with the 2 ng/mL minimum detection level required by the World Anti-Doping Agency (WADA) for all the target peptides. To demonstrate the feasibility of the work, urine samples obtained from patients who have been treated with desmopressin or leuprolide and urine samples that have been declared as adverse analytical findings were analyzed. Graphical Abstract ᅟ.

A smartphone camera for the structure from motion reconstruction for measuring soil surface variations and soil loss due to erosion

The suitability of a smartphone camera for the structure from motion (SfM) reconstruction for monitoring variations in soil surface characteristics and soil loss originated by a low intensity erosive event was evaluated. Terrestrial laser scanning (TLS) was used to validate the SfM model. Two surveys of the soil surface, one before and one after the rainfall event, were carried out for SfM and TLS. The point clouds obtained by the SfM were compared to the TLS point clouds (used as reference). From the point clouds, digital elevation models (DEMs) (0.01 m × 0.01 m) were obtained. The differences of the DEMs (DoDs) obtained from the two surveys for SfM and TLS were compared. To assess the uncertainty of the DEMs, from the DoDs the minimum level of detection was derived. The soil loss was evaluated from DoDs (for SfM and TLS, respectively) considering negative values as erosion and positive values as deposition. The SfM appears appropriate and sensitive for detecting small soil surface variations induced by low erosive events. The SfM estimated correctly the measured soil loss, while TLS underestimated 26%. Further studies could be carried out to consolidate these first results.

Characterization of micro-resonator based on enhanced metal insulator semiconductor capacitor for glucose recognition

We present a concept for the characterization of micro-fabricated based resonator incorporating air-bridge metal-insulator-semiconductor (MIS) capacitor to continuously monitor an individual's state of glucose levels based on frequency variation. The investigation revealed that, the micro-resonator based on MIS capacitor holds considerable promise for implementation and recognition as a glucose sensor for human serum. The discrepancy in complex permittivity as a result of enhanced capacitor was achieved for the detection and determination of random glucose concentration levels using a unique variation of capacitor that indeed results in an adequate variation of the resonance frequency. Moreover, the design and development of micro-resonator with enhanced MIS capacitor generate a resolution of 112.38 × 10−3pF/mg/dl, minimum detectable glucose level of 7.45mg/dl, and a limit of quantification of 22.58mg/dl. Additionally, this unique approach offers long-term reliability for mediator-free glucose sensing with a relative standard deviation of less than 0.5%.

Inactivation Kinetics ofVibrio parahaemolyticuson Sand Shrimp(Metapenaeus ensis)by Cinnamaldehyde at 4°C

Sand shrimp(Metapenaeus ensis), shrimp shell, and shrimp meat were inoculated with a three-strain cocktail ofVibrio parahaemolyticuswith or without the natural antimicrobial cinnamaldehyde (2.5 mg/ml) and were, then, stored at 4°C for up to 25 days and 18 inactivation curves were obtained.V. parahaemolyticuswere inactivated down to the minimum level of detection (2.48 log CFU/g) on thiosulfate citrate bile salts sucrose agar (TCBS) plates within 7 and 10 days with low and high densities ofV. parahaemolyticusinoculation, 4.5 log CFU/g and 8.2 log CFU/g, respectively. With adding cinnamaldehyde, the inactivation process ofV. parahaemolyticuswith low populations, 4.5 log CFU/g, lasted for only 4 days. Therefore, cinnamaldehyde inactivated cells faster as expected. However, unexpectedly, in shrimp meat cases, cells have much more persistence of over even 25 days before entering the minimum level of detection both with and without cinnamaldehyde treatment. Therefore, a hypothesis was formed that when cells kept in cold environments (4°C) after several days recovered to up to 103–104CFU/g towards the end of the experiments and with starvation (shell and shrimp studies), cells might render a viable but nonculturable (VBNC) state.

Improvement in minimum detectable activity for low energy gamma by optimization in counting geometry

Gamma spectrometry for environmental samples of low specific activities demands low minimum detection levels of measurement. An attempt has been made to lower the gamma detection level of measurement by optimizing the sample geometry, without compromising on the sample size. Gamma energy of 50–200 keV range was chosen for the study, since low energy gamma photons suffer the most self-attenuation within matrix. The simulation study was carried out using MCNP based software “EffCalcMC” for silica matrix and cylindrical geometries. A volume of 250 ml sample geometry of 9 cm diameter is optimized as the best suitable geometry for use, against the in-practice 7 cm diameter geometry of same volume. An increase in efficiency of 10%–23% was observed for the 50–200 keV gamma energy range and a corresponding lower minimum detectable activity of 9%–20% could be achieved for the same.

Biorecognition in Organic Field Effect Transistors Biosensors: The Role of the Density of States of the Organic Semiconductor.

Biorecognition is a central event in biological processes in the living systems that is also widely exploited in technological and health applications. We demonstrate that the Electrolyte Gated Organic Field Effect Transistor (EGOFET) is an ultrasensitive and specific device that allows us to quantitatively assess the thermodynamics of biomolecular recognition between a human antibody and its antigen, namely, the inflammatory cytokine TNFα at the solid/liquid interface. The EGOFET biosensor exhibits a superexponential response at TNFα concentration below 1 nM with a minimum detection level of 100 pM. The sensitivity of the device depends on the analyte concentration, reaching a maximum in the range of clinically relevant TNFα concentrations when the EGOFET is operated in the subthreshold regime. At concentrations greater than 1 nM the response scales linearly with the concentration. The sensitivity and the dynamic range are both modulated by the gate voltage. These results are explained by establishing the correlation between the sensitivity and the density of states (DOS) of the organic semiconductor. Then, the superexponential response arises from the energy-dependence of the tail of the DOS of the HOMO level. From the gate voltage-dependent response, we extract the binding constant, as well as the changes of the surface charge and the effective capacitance accompanying biorecognition at the electrode surface. Finally, we demonstrate the detection of TNFα in human-plasma derived samples as an example for point-of-care application.

Integrating Genetic Risk Factors with Age, Presenting White Cell Count and MRD Response As Continuous Variables to Predict Relapse in Paediatric Acute Lymphoblastic Leukemia (ALL)

▪Paediatric ALL is heterogeneous in terms of clinical presentation, response to therapy and underlying genetic mechanisms. The application of treatment stratification algorithms has resulted in survival rates exceeding 90%. However, current algorithms apply risk factors as binary variables using arbitrary thresholds and in an independent manner. This approach potentially distorts biological heterogeneity resulting in loss of prediction accuracy. Therefore, we sought to determine whether treating clinical risk factors and MRD response as continuous variables and integrating genetic features can refine prognostication.A total of 2542 patients, aged 1-24 years old, recruited to UKALL2003 were available for analysis. NCI standard/high patients were initially assigned to regimen A/B. Sow early responders and those with HR genetics were transferred to the more intensive regimen C. Minimal residual disease (MRD) was evaluated at the end of induction (EOI) by real-time quantitative PCR analysis of Ig/TCR rearrangements. Patients with EOI MRD >0.01% were randomised to stay on regimen A/B or move to C whereas patients with EOI MRD <0.01% were randomised to receive one or two delayed intensifications. Genetic subtypes were defined as good risk (GRcyto: ETV6-RUNX1, high hyperdiploidy), high risk (HRcyto: KMT2A fusions, near haploidy, low hypodiploidy, iAMP21 and TCF3-HLF), intermediate risk (other B cell precursor cases) and T-ALL.In order to examine MRD as a continuous variable, we log transformed the raw EOI MRD value assuming a minimum detection level of 0.00001 and assigned cases with undetectable MRD a value of one log below this threshold. The transformed MRD variable [t(MRD)] followed a log normal distribution (Figure 1). Importantly, this log normal distribution was distinct across the genetic subtypes (Figure 1, p<0.001); even after accounting for the different induction regimens used. Using the t(MRD) variable, we show that each log reduction in EOI MRD reduces the relapse risk (RR) by 22% (p<0.001). In the current UK paediatric trial (UKALL2011) an MRD threshold of 0.005% is used to assign patients to regimen C. Therefore, we examined the RR by MRD value within each genetic subtype. Table 1 shows that the RR for GRcyto patients remains low (<4%) up to an MRD threshold of 0.1% and treatment intensification did not further reduce this RR. In light of these data, we have changed the MRD threshold for classifying newly diagnosed GRcyto patients as MRD risk from 0.005% to 0.1%. This treatment intervention reduces the proportion of GRcyto patients who receive the most intensive therapy (regimen C) from ~40% to <10% and therefore avoids potential unnecessary toxicity.Next we combined multiple significant risk factors from univariate analysis using forward selection modelling to fit a multivariate prognostic model. The final model included log(WCC) and t(MRD) as continuous variables and two binary genetic variables: GRcyto and HRcyto. Using the coefficients from this model, we constructed a linear model which enabled the calculation of individual risk scores. Figure 2 shows the correlation between an individual’s risk score and their RR. To investigate the clinical relevance of this risk score, we generated five risk groups based on ascending RR (Table 2) which have significant differential outcomes (all p<0.001). Using this classification, 65% patients are very low or low (VLR/LR) risk while 11% are high or very high risk (HR/VHR). Although the HR/VHR groups are small their RR was >25% and together with the standard risk (SR) group capture >70% relapses and, importantly, >80% of HR relapses (very early/early relapses). Among the 136 VLR/LR patients who had MRD >0.01%, there was no difference in EFS between patients randomised to regimen A/B v C (97% v 99%, p=0.5). Equally among 470 VLR/LR patients with MRD <0.01%, there was no difference in EFS between patients randomised to receive 1 or 2 delayed intensifications (96% v 96%, p=0.8).In conclusion, we have showed that EOI MRD is log normally distributed but that the shape of the distribution depends on genetic subtype; suggesting differential MRD kinetics. In addition, we have shown that using a single MRD threshold does not reflect the biological heterogeneity that is a fundamental feature of the disease. Finally, we demonstrate that integrating clinical risk factors as continuous variables with genetics can better define prognostic subgroups. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

SERS-based ultrasensitive detection of organophosphorus nerve agents via substrate’s surface modification

Highly efficient detection of the organicphosphor nerve agents such as sarin and soman, based on surface enhanced Raman scattering (SERS) effect, has been in challenge due to their weak adsorption property on coin metals. In this paper, a new strategy is presented to achieve the SERS-based ultrasensitive detection of sarin-simulated agent methanephosphonic acid (MPA) via the surface modification of SERS-substrates. The Au-coated Si nanocone array is surface-modified with 2-aminoethanethiol and used as SERS-substrate for detection of MPA. It has been shown that the modified substrate could preferentially capture MPA molecules in the solution with coupling agent and induce amidation reaction. The reaction products are still bound or anchor on the substrate’s surface. The MPA molecules can thus be detected by Raman spectral measurement of the solution-soaked SERS-substrate. The minimum detection level is down to ∼1ppb. The Raman peak intensity versus the MPA concentration is subject to a linear double logarithmic relation from ∼1ppb to ∼1000ppm, which is attributed to Freundlich adsorption of MPA on the surface-modified SERS substrate. This study provides a new way for the highly efficient SERS-based detection of the organophosphorus nerve agents and some other target molecules weakly interacted with metal substrates.

Detection of Emerging Food Pathogens in Chicken Meat Using Multiplex Polymerase Chain Reaction

&lt;p&gt;A study was undertaken to develop a multiplex PCR (m-PCR) protocol for simultaneous detection of &lt;em&gt;Campylobacter jejuni &lt;/em&gt;and &lt;em&gt;Listeria monocytogenes &lt;/em&gt;in chicken meat. The extraction of DNA was carried out using commercial DNA extraction kit, Phenol Chloroform and boiling method. Samples with OD ratio (260:280) between 1.7 and 1.9 were considered good in terms of concentration and purity and were used for PCR amplification. DNA extraction kit and Phenol Chloroform method revealed good OD value were used for sample extraction process. PCR and m-PCR amplification was carried out using genus specific primers were designed by targeting its&lt;em&gt; Hyp &lt;/em&gt;(500 bp) and &lt;em&gt;prfA &lt;/em&gt;(290 bp) gene for &lt;em&gt;Campylobacter jejuni &lt;/em&gt;and &lt;em&gt;Listeria monocytogenes&lt;/em&gt; respectively. Electrophoresis of amplified PCR products and gel documentation revealed 500 bp and 290 bp in 2% Agarose.&lt;strong&gt; &lt;/strong&gt;The multiplex PCR technique was standardized using the reference strains with the similar amplification procedure. The minimum detection level (sensitivity) by mPCR for &lt;em&gt;Campylobacter jejuni &lt;/em&gt;and &lt;em&gt;Listeria monocytogenes&lt;/em&gt; was found to be 0.2 ng/ul and 1.0 ng/ul of DNA in a reaction mixture (25 ul). The developed multiplex PCR technique could detect &lt;em&gt;Campylobacter jejuni &lt;/em&gt;and &lt;em&gt;Listeria monocytogenes&lt;/em&gt; upto 3 × 10&lt;sup&gt;5&lt;/sup&gt; and 3 × 10&lt;sup&gt;4&lt;/sup&gt; CFU/ml of artificially inoculated meat homogenate. Around 60 chicken meat samples were collected from different regions of chennai and were screened for the presence of &lt;em&gt;Campylobacter jejuni&lt;/em&gt; and &lt;em&gt;Listeria monocytogenes&lt;/em&gt;. All the samples screened were not positive either for &lt;em&gt;Campylobacter jejuni&lt;/em&gt; and &lt;em&gt;Listeria monocytogenes&lt;/em&gt;. The negative samples were further checked by culture methods and good correlation between these two methods was observed. Hence, the m-PCR technique developed in this study can be used as a rapid screening test for detection of &lt;em&gt;Campylobacter jejuni &lt;/em&gt;and &lt;em&gt;Listeria monocytogenes&lt;/em&gt; from chicken meat within 24 hours.&lt;/p&gt;

Evaluation of the occupational X-rays dose of the medical staff in a cardiac catheterization laboratory using an acrylic phantom and semiconductor dosimeter.

The occupational X-rays doses of medical staff in a cardiac catheterization laboratory were evaluated. Four customized acrylic phantoms were used to simulate a patient, medical doctor, assistant, and radiologist to evaluate the in-situ X-rays exposure dose using semiconductor dosimeters. The exposure dose was measured under three scenarios that were preset to imply: no shielding, moderate shielding and complete shielding for the medical staff in the laboratory. The doses were applied by changing the dose area product (DAP) from 11,000 to 500,000mGy·cm(2) in 14 increments. The estimated annual occupational doses for doctors, assistants and radiologists in scenarios I, II, and III were: I) 35.03, 7.78, 1.95; II) 1.95, 0.78, 0.06; and III) 0.19, 0.10, 0.05cSv, respectively. The derived linear regression line of the exposure dose with respect to the DAP were extrapolated to obtain the minimum detectable level (MDL) of DAP for triggering the staff dosimeters. Accordingly, the minimum annual dose was estimated as 0.05cSv. Additional shielding provided measurable protection to the staff. The protective clothing used in scenarios II and III can reduce the original dose from scenario I to ∼3% (scenario II) and ∼0.5% (scenario III). The annual occupational dose also changed with the various X-rays energy settings. The annual dose increased to 126% when the preset X-rays energy was changed from 70 to 100kVp. The semiconductor dosimeter proved to be an adequate tool for measuring low doses and low dose rates under these circumstances. The dose can be reduce of I) 35.03, 7.78, 1.95; to II) 1.95, 0.78, 0.06 (∼3%); or III) 0.19, 0.10, 0.05 (∼0.5%)cSv, respectively according to different protective scenarios.

High Surface-Enhanced Raman Scattering (SERS) Amplification Factor Obtained with Silver Printed Circuit Boards and the Influence of Phenolic Resins for the Characterization of the Pesticide Thiram.

In this work, low-cost substrates with rough silver surfaces were prepared from commercial copper foil-covered phenolic board (CPB) and an aqueous solution of AgNO3, and were used for surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) measurements. A maximum SERS amplification factor of 1.2 × 10(7) was obtained for Rhodamine 6G (R6G), and use of the CPB resulted in a detection limit for Thiram pesticide of 0.5 µmol L(-1) The minimum detection level was limited by residual traces of phenolic groups that originated from the substrate resin, which became solubilized in the aqueous Ag(+) solution. It was found that the bands corresponding to the impurities had less influence in the Thiram analysis, which could be explained by the high affinity of sulfur for Ag surfaces. The influence of impurities in the SERS analyses therefore depended on the linkage between the rough silver surface and the analyte. The findings demonstrated the ease and effectiveness of using CPB to prepare a nanostructured surface for SERS.

Effects of microwave and conventional blank roasting on oxidation behavior, microstructure and surface morphology of vanadium slag with high chromium content

The effects of microwave blank roasting (MBR) and conventional blank roasting (CBR) on oxidation behavior,microstructure and surface morphology of vanadium slag with high chromium content (VSHCC) containing 12.54 wt% Cr2O3 were investigated. The oxidation behavior, microstructure and surface morphology of samples before and after MBR and CBR were characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), simultaneous thermal gravimetric and differential scanning calorimetry (TG-DSC) and scanning electron microscope (SEM), respectively. The MBR experiments were performed in a microwave roasting instrument at temperature ranging from 400 °C to 900 °C and the CBR experiments were performed in muffle furnace at temperature ranging from 600 °C to 900 °C. The results show that the normal spinel begins to be oxidized to inverse spinel at a lower temperature and to decompose at 600 °C. The completely decomposition temperatures of the normal spinel using MBR and CBR are 700 °C and 800 °C, respectively. The formation temperatures of Fe2TiO5 using MBR and CBR are 600 °C and 900 °C, respectively, and the content of Fe2TiO5 and (Fe0.6,Cr0.4)2O3 gradually increase as MBR temperature (from 600 °C to 900 °C) increases. After roasted at a high temperature, the majority of Cr3+ ions in the spinel phase are conjugated to iron ions to form hematite-type (Fe0.6,Cr0.4)2O3 solid solutions and the minority of Cr3+ ions in the spinel phase are incorporated into VO2 to form the Cr0.07V1.93O4 or CrVO4. The completely decomposition temperature of the olivine revealed by FT-IR analysis is higher than that concluded from the XRD analysis. The reason is that the minimum detection level of FT-IR analysis is more sensitive than the XRD analysis. Compared with the CBR, the MBR can accelerate the oxidative decomposition of the spinel and olivine phase in the raw slag and also can lower the formation temperature of Fe2TiO5. Besides, it also can reduce the granularity of roasted particles and make the surface become more porous especially at a high roasting temperature. The reason for this phenomenon can be due to the different of heat generation and heat transferring mechanisms in MBR and CBR. Based on the results, a new approach has been proposed to extract vanadium from VSHCC. At last, kinetic analysis indicates that the oxidative decomposition of vanadium chromium spinel phase is controlled by the rate of 0.43 reaction order and the corresponding total apparent activation energy and the frequency factor are 112.57 kJ mol−1 and 1.86 × 104 min−1, respectively.