Minimum Detectable Level Research Articles

Fabrication of Platinum Villus Overlaid Porous Carbon Nanoweb Layers for Hydrogen Gas Sensor Application

AbstractPlatinum (Pt) villus structure is introduced on the porous carbon nanoweb layers (PCNWLs) by electrochemical deposition under acidic condition. The PCNWLs are simply fabricated by spin‐coating method with a polymer mixture solution, and by sequential thermal treatment. The Pt structure grows from particle to villus shape with different deposition voltages. Moreover, the size of Pt villus structures increases with the increase in the concentration of Pt precursor from 0.1 × 10−3 to 5 × 10−3 m. The Pt villus overlaid porous carbon nanoweb layers (PtPCNWLs)‐based hydrogen gas (H2) sensor demonstrates excellent gas sensing performances due to its catalytic hydrogen gas sensing mechanism. The minimum detection level (MDL) of the PtPCNWLs‐based H2 gas sensor is 10 ppm and exhibits linear range from 10 to 200 ppm. The PtPCNWLs‐based H2 gas sensor also demonstrates excellent cyclic stability, reusability, and durability.

High-Performance Conducting Polymer Nanotube-based Liquid-Ion Gated Field-Effect Transistor Aptasensor for Dopamine Exocytosis

In this study, ultrasensitive and precise detection of a representative brain hormone, dopamine (DA), was demonstrated using functional conducting polymer nanotubes modified with aptamers. A high-performance aptasensor was composed of interdigitated microelectrodes (IMEs), carboxylated polypyrrole nanotubes (CPNTs) and DA-specific aptamers. The biosensors were constructed by sequential conjugation of CPNTs and aptamer molecules on the IMEs, and the substrate was integrated into a liquid-ion gating system surrounded by pH 7.4 buffer as an electrolyte. To confirm DA exocytosis based on aptasensors, DA sensitivity and selectivity were monitored using liquid-ion gated field-effect transistors (FETs). The minimum detection level (MDL; 100 pM) of the aptasensors was determined, and their MDL was optimized by controlling the diameter of the CPNTs owing to their different capacities for aptamer introduction. The MDL of CPNT aptasensors is sufficient for discriminating between healthy and unhealthy individuals because the total DA concentration in the blood of normal person is generally determined to be ca. 0.5 to 6.2 ng/mL (3.9 to 40.5 nM) by high-performance liquid chromatography (HPLC) (this information was obtained from a guidebook “Evidence-Based Medicine 2018 SCL “ which was published by Seoul Clinical Laboratory). The CPNTs with the smaller diameters (CPNT2: ca. 120 nm) showed 100 times higher sensitivity and selectivity than the wider CPNTs (CPNT1: ca. 200 nm). Moreover, the aptasensors based on CPNTs had excellent DA discrimination in the presence of various neurotransmitters. Based on the excellent sensing properties of these aptasensors, the DA levels of exogeneous DA samples that were prepared from PC12 cells by a DA release assay were successfully measured by DA kits, and the aptasensor sensing properties were compared to those of standard DA reagents. Finally, the real-time response values to the various exogeneous DA release levels were similar to those of a standard DA aptasensor. Therefore, CPNT-based aptasensors provide efficient and rapid DA screening for neuron-mediated genetic diseases such as Parkinson’s disease.

Compositions of Cu-(Fe)-Sulfides in the 109 Reduced Granite-Related Cu Deposit, Xinjiang, Northwest China: Implications to the Characteristics of Ore-Forming Fluids

In general, porphyry Cu deposit is related to the highly oxidized ore-forming system. However, there are many porphyry Cu deposits that are related to the reduced ore-forming system, and the ore-forming characteristics of reduced porphyry Cu deposit are unclear. Cu-(Fe)-sulfides are the main Cu-hosting minerals in porphyry Cu deposits and are also economically important, and the composition of Cu-(Fe)-sulfides has closely relationship with ore-forming characteristics. In this study, concentration data obtained via laser ablation inductively coupled plasma mass spectrometry are reported for chalcopyrite, bornite, and chalcocite from the 109 porphyry Cu deposit formed in a reduced granite-related mineralization system in western Tianshan, Xinjiang, northwest China. The results show that the chalcopyrite hosts several trace elements including Zn, Ge, Se, In, and Sn; the bornite hosts Mo, Ag, Zn, Se, and Bi; and the chalcocite hosts Mo, Ag, Zn, Sn, Se, and Bi. The smooth time-resolved depths profiles and limited variations of trace element concentrations in these sulfides suggest that their presence is isomorphic. The microstructures of the chalcopyrite and bornite were observed by high-resolution transmission electron microscopy. Their lattices are neatly arranged, also indicating that the trace elements exist mainly as isomorphisms in the chalcopyrite and bornite. Ge, Sn, and In are hosted in the chalcopyrite but absent in bornite and chalcocite, indicating that chalcopyrite has a high potential for hosting these elements. Ge and Sn are preferentially hosted in the chalcopyrite, possibly due to relatively high temperatures and low oxygen fugacity during its formation. Indium is preferentially hosted in the chalcopyrite, possibly due to the In2+ substitution for Fe2+ controlled by Goldschmidt’s rules, which state that substitution occurs between a substituent and host owing to similarities in their radii and charges. However, the concentration of Ag is low in chalcopyrite but significantly high in bornite and chalcocite, indicating that this element is preferentially hosted in the latter two minerals. The abundance of Ag, a low-temperature element, in Cu-(Fe)-sulfides may largely be dependent on temperature. The Au content is below the minimum level of detection in all sulfides, which is obviously different from the classic porphyry copper deposits. In addition, the concentrations of Zn, Ge, As, Sb, and Te in the chalcopyrite and those of Zn, Se, As, Sb, and Bi in the bornite from the 109 porphyry Cu deposit show obvious differences from those of classic porphyry Cu deposits. Therefore, some elements in Cu-(Fe)-sulfides can be used as indicators of ore-forming oxygen fugacity. Bornite and chalcocite are generally enriched in Ag, indicating that the mining of porphyry Cu deposits may be concerned with the precious metal Ag in bornite and chalcocite. In addition, chalcopyrite may host sufficient Se and Zn, and bornite and chalcocite could host sufficient Se, Zn, and Bi, suggesting that sulfides may be hosts for deleterious elements.

Hepatitis B virus reactivation in kidney transplant patients with resolved hepatitis B virus infection: Risk factors and the safety and efficacy of preemptive therapy.

Hepatitis B virus (HBV) reactivation is associated with complications and adverse outcomes in patients with clinically resolved HBV infection who are seronegative for hepatitis B surface antigen (HBs Ag), and seropositive for hepatitis B core antibody (HBc Ab) and/or hepatitis B surface antibody (HBs Ab) before kidney transplantation (KT). We retrospectively analyzed 52 patients with resolved HBV infection who were HBV-DNA negative. HBV-DNA after KT was evaluated, and the occurrence of HBV reactivation and outcomes were monitored. We defined HBV reactivation as seropositivity for HBV-DNA at or above the minimal detection level of 1.0log IU/mL and treated preemptively (using entecavir) when the HBV-DNA level was at or above 1.3log IU/mL, in accordance with the Japanese Guidelines for HBV treatment. Among the 52 patients, the mean age was 57.2±10.8years. The median HBc Ab titer was 12.8 (interquartile range, 4.6-42.6) cutoff index, and five (9.6%) cases of HBV reactivation occurred. No patients developed graft loss and died due to HBV reactivation. Statistical analysis showed that age and HBc Ab titer were significant risk factors for HBV reactivation (P=.037 and P=.042, respectively). No significant differences were found between graft survival and the presence or absence of HBV reactivation. These results suggest that HBc Ab titer and age could be significant risk factors for HBV reactivation. Resolution of HBV infection did not appear to be associated with patient or graft survival, regardless of whether HBV reactivation occurred, when following our preemptive strategy.

Five-channel fiber-based laser Doppler vibrometer for underwater acoustic field measurement.

In this paper, a 1550 nm five-channel all-fiber homodyne laser Doppler vibrometer with high sensitivity and good signal probing probability is presented. Under the anechoic tank, standing on an airborne platform above the water surface 3 m away, the calibration experiments of the designed system are conducted. The minimum detectable sound pressure level is up to 101.73 dB re 1 µPa at 10 kHz under the hydrostatic water surface condition, and the time distribution of the final outputs are consistent with that of the underwater sound transducer. For the hydrodynamic detection capability, with the help of a 1064 nm high-pulse-energy laser whose pulse energy is 6J, pulse duration is about 8 ns, and repetition rate is 1 Hz, the system performance is tested in Qiandao Lake. And the signal probing probability of the whole sensing system is up to 59.77%.

Implementation of a pulse-type laser detection and ranging system based on heterodyne detection for long-range measurement with high repetition rate.

This paper presents the implementation of a pulse-type LAser Detection And Ranging (LADAR) system based on heterodyne detection for long-range measurement. A pulse-type LADAR based on an intensity direct-detection is certainly simple and mature, but it requires a high peak-power laser and a low-noise avalanche photodiode for long-range measurement, which restricts the scope of the application due to the weight, power consumption, and cost of the laser and the photodetector. In this work, heterodyne detection using a PIN photodiode is implemented to increase receiver sensitivity instead of using a low-noise avalanche photodiode. An optical phase-locked loop is adopted to generate an optical local oscillator signal for heterodyne detection. The proposed heterodyne detection scheme achieves a minimum detectable signal level of -52.6 dBm at a bandwidth of 1.2 GHz, and it is adopted in a pulse-type LADAR system for long-range measurement. The pulse-type LADAR system can measure a distance of 2.77 km at a repetition rate of 40 kHz, and it demonstrates great advantages for realizing real-time 3D imaging for long-range measurement with a high frame rate.

Inkjet printed kirigami inspired split ring resonator for disposable, low cost strain sensor applications

The purpose of this study was to produce a kirigami inspired split ring resonator (SRR) strain sensor. Since the SRR resonance frequency depends strongly on its split gap, one kirigami cut was designed to align with the SRR split gap, allowing SRR resonance frequency to be varied by applying tensile stress. The relationship between frequency and induced strain helps to explain the strain sensing mechanism. Two sheets of paper were used as the dielectric for compatibility with the kirigami technique, and a conductive pattern was inkjet printed on the top paper using silver nanoparticle ink, whereas the ground plane on the bottom paper was inkjet printed using stretchable ink. The two papers were bonded using epoxy strain sensor and S parameters for the fabricated sensor were measured at different strain levels. Resonance frequency increased from 4 to 4.64 GHz for 17.24% applied strain, with measured strain sensitivity = 4.2 × 107 Hz/% and minimum detectable strain level ≈0.84%. Measurement results were compared with simulation results. The proposed strain sensor is relatively easy to manufacture, low cost, and disposable because it was inkjet printed on paper.

Factors affecting Alicyclobacillus acidoterrestris growth and guaiacol production and controlling apple juice spoilage by lauric arginate and ϵ-polylysine

Growth of Alicyclobacillus acidoterrestris in fruit juices has been associated with the release of off-odor compounds, such as guaiacol. Guaiacol release was quantified using Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) and method's minimum detection level was 3.6 ppb. The amount of guaiacol released was dependent on the amount of vanillin added to the medium. Sucrose-supplemented yeast starch glucose broth (SS-YSG broth; pH 3.7) and apple juice were spiked with vanillin (10 mg/L), inoculated with A. acidoterrestris and incubated at different temperatures (20°C–45 °C) for up to 528 h. At the temperatures that permitted growth, the bacterium grew slower in apple juice than in SS-YSG broth. Bacterial growth and guaiacol production were prevented in apple juice and inhibited in SS-YSG, when the inoculated products were incubated at 20 °C and 25 °C. When Alicyclobacillus was inoculated in SS-YSG adjusted to pH 2.7–6.7 and incubated at 37 °C, growth of the bacterium and guaiacol production were suppressed at pH 6.7 for up to 354 h and delayed at pH 2.7. Lauric arginate and ϵ-polylysine inactivated Alicyclobacillus cells with no guaiacol production in both SS-YSG and apple juice. However, ϵ-polylysine was more effective than lauric arginate when the SS-YSG (pH 3.7) was inoculated with Alicyclobacillus spores.

Measurement of activity concentrations of 238U, 226Ra, 232Th and 40K in different dental ceramic materials and assessment of dose given to oral mucosa

In this study, the beta dose given to oral epithelium was estimated from the activities of radionuclides 238U, 232Th, 226Ra and 40K in feldspathic and zirconium dioxide (ZrO2) dental ceramics before and after the sintering process. They were measured using a well -type HPGe detector. 232Th activity is generally below the minimum detectable level of 1.6 Bq⋅kg−1 in all samples and 238U activity was far below the 1000 Bq⋅kg−1 limit stipulated by ISO 6872 standard. However, 226Ra activity was observed in all samples except for ZrO2 core samples ranged from 8.3 ± 1.1 to 105 ± 4 Bq⋅kg−1. Considerable 40K activity was observed in the feldspathic ceramic and ZrO2 veneer ceramic samples (between 1564 ± 48 Bq⋅kg−1 and 2703 ± 84 Bq⋅kg−1). The beta dose to oral epithelium tissue calculated from the measured activities was determined to be 1.5 mGy/y in a worse-case scenario in which all teeth were restored with dental ceramics. All results indicate that there is no concern about extra beta dose given to oral epithelium due to zirconia used as dental ceramics.

Assessment of radioactivity in commercially available honey in Italy

Activity concentration of natural radionuclides and 137Cs were estimated in 28 honeys purchased from large supermarket chains in Italy. Uranium, polonium and thorium were measured by alpha spectrometry, 40 K and 137Cs by gamma spectrometry and 226Ra by liquid scintillation. The concentrations were 50.6 ± 46.3, 0.023 ± 0.010, 0.019 ± 0.017, 0.27 ± 0.40 Bqkg−1 for 40 K, 238U, 234U and 210Po respectively. 235U, 228Th, 232Th were consistently <0.007 Bqkg−1 and 226Ra <0.200 Bqkg−1. 137Cs was <2.1 Bqkg−1 in 93% of the samples. The activity of radiocesium was found to be above the minimum detectable level in only two samples and did not exceed the highest permitted level for food contributing to the overall radioactivity only slightly. The effective doses attributable to 210Po accounts for 0.0026–5.31% of global human exposure to natural radiation. The honeys that were tested were found to be of good quality with regard to the parameters under study, confirming the general image of honey as a genuine healthy product.

Utility Of An Automatic Limulus Amebocyte Lysate Kinetic Turbidimetric Test For Endotoxin Screening Of Dialysate Samples.

BackgroundEndotoxin contamination of dialysate has serious adverse effects on patients undergoing hemodialysis. Therefore, endotoxin activity in dialysate is closely monitored. Limulus amebocyte lysate (LAL) has been used as a reagent to measure endotoxin activity. Here, we investigated the efficacy of an automatic LAL kinetic turbidimetric test (Toxinometer ET-mini) for screening endotoxin activity in dialysate.MethodsIn total, endotoxin activity was measured in 110 dialysate samples obtained from several sites within hemodialysis circuits between June 2012 and March 2018. The results were compared with those from a conventional chromogenic substrate LAL test conducted by a clinical examination laboratory.ResultsBoth the automatic LAL test and the chromogenic substrate LAL test had a minimum detection level of 0.001 endotoxin units (EU)/mL. Endotoxin activity levels measured via the automatic LAL test showed a strongly positive correlation (concordance correlation coefficient: 0.9933; 95% CI: 0.9902–0.9954) and good agreement (mean difference: 0.00±0.01 EU/mL) with those obtained using the chromogenic substrate LAL test.ConclusionThe results suggest that the automatic LAL test may be useful for endotoxin activity screening in hemodialysis facilities.

Identification of Small Berry Species in Food and Juice Using TaqMan-Based Real-Time PCR

Abstract Background: Public interest is growing for small berries in recent years because they are very delicious, low in energy, and full of bioactive compounds with potential health benefits. Similar to other food products, adulteration of small berry fruit products poses economic and safety problems to consumers. Objective: To protect consumers and regulate the small berry fruit products market, it is necessary to establish a robust method for detecting the authenticity. Methods: In this study, TaqMan-based real-time PCR assay was established for species identification of cranberry, raspberry, and blueberry to ensure authenticity of commercial small berry food products (pulp, dried fruit, fruit juice, jam, and puree). Results: Absolute detection limit was 0.1 pg/μL DNA for raspberries, 1 pg/μL DNA for blueberries, and 10 pg/μL DNA for cranberries. Practical LOD was 0.1% (v/v) for fresh juice. For processed juice, practical LOD was 1% for blueberry and red raspberries, 0.1% for black and yellow raspberries, and 5% for cranberry. Conclusions: The method was shown to be functional and effective to detect the raw material composition of cranberry, raspberry, and blueberry for commercial products. Highlights: TaqMan probe-based real-time PCR methods were designed to identify three small berries (blueberry, raspberry, and cranberry) in berry products. Efficient DNA recovery methods and detection strategy were established to ensure correct and sensitive testing of fresh small berries exhibited a detection limit of 0.1 to 10 pg/μL. The practical minimum detection levels were 0.1 to 5% in fresh and processed juice, including pasteurization and HTHP.

A novel approach to detect highly manipulated fat adulterant as Reichert-Meissl value-adjuster in ghee (clarified butter) through signature peaks by gas chromatography of triglycerides.

Ghee, the clarified butter fat being the costliest fat among other edible oils and fats in India, prone to adulteration with highly manipulated cheaper oils/fats, especially during lean season. The present investigation carried on triglycerides profile of one of the latest components of the adulterant fat i.e. RM (Reichert-Meissl)-adjuster, has been exploited to check the adulteration of ghee with a newly emerged highly manipulated fat. Using standardized (S)-limits specified by the ISO/IDF for cow milk fat, the minimum level of detection of the adulterant fat was observed as 7.5%. However, in case of buffalo ghee, due to non-availability of the ISO/IDF limits, the detection of this adulterant fat in buffalo ghee was not possible. Gas chromatograms showed specific signature peaks of large size in the retention time region of 4.5 to 6.5min for RM-adjuster and adulterant fat, whereas no such peaks were observed in pure cow and buffalo ghee samples. The new approach of zooming in and superimposing of selected peaks in the chromatograms of triglycerides of suspected ghee has been used as a strategy to find adulterant fat's presence. Through this approach, the addition of RM-adjusted highly manipulated foreign fat (adulterant fat) to the tune of even 0.5% could be achieved in both cow as well as buffalo ghee.

Selective media and real-time PCR assays for the effective detection of enterotoxigenic Escherichia coli in vegetables

Enterotoxigenic Escherichia coli (ETEC) is a major foodborne pathogen. Along with water, vegetables are one of the major food sources related to infections. Effective detection methods for ETEC in food, however, have not yet been established. This study aimed to evaluate ETEC detection methods focusing on the major serogroups (O6, O25, O27, O148, O153, O159, and O169) with steps of enrichment, isolation, and real-time PCR targeting genes encoding the heat-labile enterotoxin (LT) and heat-stable enterotoxin (ST). ETEC strains (n = 20) were grown to 7.0–8.9 log CFU/mL in modified E. coli broth (mEC) at 42 °C for 18 h. The strains formed colonies typically representing E. coli on sorbitol MacConkey agar and Shiga toxin-producing E. coli on CHROMagar STEC base agar. The minimum detection levels for real-time PCR assays targeting LT and ST genes were 1.9–3.1 log CFU/mL of vegetable culture. Vegetables inoculated with 2.0 log CFU/g ETEC were cultured in mEC, and then ST and LT genes were detected in the culture by real-time PCR assays at low threshold cycle (Ct) values; further, ETEC in the culture was isolated by plating on agars. This study thus demonstrated effective detection methods for ETEC in vegetables.

Changing the Blood Test: Accurate Determination of Mercury(II) in One Microliter of Blood Using Oriented ZnO Nanobelt Array Film Solution-Gated Transistor Chips.

The measurement of ultralow concentrations of heavy metal ions (HMIs) in blood is challenging. A new strategy for the determination of mercury ions (Hg2+ ) based on an oriented ZnO nanobelt (ZnO-NB) film solution-gated field-effect transistor (FET) chip is adopted. The FET chips are fabricated with ZnO-NB film channels with different orientations utilizing the Langmuir-Blodgett (L-B) assembly technique. The combined simulation and I-V behavior results show that the nanodevice with ZnO-NBs parallel to the channel has exceptional performance. The sensing capability of the oriented ZnO-NB film FET chips corresponds to an ultralow minimum detectable level (MDL) of 100 × 10-12 m in deionized water due to the change in the electrical double layer (EDL) arising from the synergism of the field-induced effect and the specific binding of Hg2+ to the thiol groups (-SH) on the film surface. Moreover, the prepared FET chips present excellent selectivity toward Hg2+ , excellent repeatability, and a rapid response time (less than 1 s) for various Hg2+ concentrations. The sensing performance corresponds to a low MDL of 10 × 10-9 m in real samples of a drop of blood.

Nondetectable or minimal detectable residue levels of N-(n-butyl) thiophosphoric triamide in bovine tissues and milk from a 28-d NBPT dosing study.

N-(n-butyl) thiophosphoric triamide (NBPT) (Figure 1) is an active ingredient in nitrogen stabilizer (urease inhibitor), which temporarily inhibits the action of the urease enzyme to improve the efficiency of urea-containing fertilizers. Given the potential for NBPT residues to be present in milk and tissues of dairy cattle, due diligence is needed to demonstrate the safety of NBPT in urea-based fertilizers used on forages and crops intended for consumption by Holstein dairy cows. This study used controlled dosing of NBPT in capsule form to dairy cattle for 28 d, followed by a 14-d depuration phase to assess the potential for residues to exist in milk and tissues of dairy cattle at exaggerated use levels. Fourteen lactating cows were selected for the dosing and depuration phases of the study, based on health, body weight (BW), and milk production. There were four treatment groups: 0 mg NBPT/kg BW (Control) (n = 2 cows), 1 mg NBPT/kg BW (1×) (n = 3 cows), 3 mg NBPT/kg BW (3×) (n = 3 cows), and 10 mg NBPT/kg/BW (10×) (n = 6 cows); levels were based on maximum tolerable amount of urea that a cow can ingest on a daily basis (1×) and the maximum concentration of NBPT commercially used when treating urea (0.1 wt% NBPT in urea). At the end of the 28-d dosing phase, cows were randomly selected for the 14-d depuration phase of the study (one control and three 10× cows). The results showed no NBPT residue is detectable at all dose levels, except that a residue level was above the lower limit of quantitation in a single milk and subcutaneous fat sample in the highest (10×) treatment group, which represents the level of NBPT that would be theoretically present in 10× the lethal dosing of daily consumable urea to a cow. Overall, the study demonstrated that it is unlikely for NBPT residues to be present in cattle milk or edible tissues or to cause negative effects on animal health under good agricultural practice.

Selective Detection of Alcohol Through Ethyl-Glucuronide Immunosensor Based on 2D Zinc Oxide Nanostructures

Alcohol intoxication leads to road accidents, violence, and the deteriorated health of heavy drinkers. Hence, a convenient means to monitor alcohol consumption with an accuracy and selective manner is a demand by law enforcement personnel, service/hospitality industry, or individual drinkers. We report on a label-free, highly sensitive, and selective alcohol immunosensor based on 2D zinc oxide nanoflakes (ZnO-NFs), which were synthesized on gold-coated flexible polyethylene terephthalate substrates using a single-step sonochemical process. Selective detection of alcohol was achieved via ethyl-glucuronide (EtG) detection by immobilizing EtG antibody (EtG-AB) on the as-synthesized sensing electrodes of ZnO-NFs. The 2D ZnO-NFs provide unique sensing advantages over bulk materials. The cyclic voltammetry and electrochemical impedance spectroscopy measurements demonstrated the sensitivity of 0.032 mA/decade/cm2 in the concentration range of 1 ng/ml to 100 $\mu \text{g}$ /ml which covered the physiological range. The minimum level of detection was determined much lower than 1 ng/ml. Shelf-life studies showed that the presented EtG sensors can be used over two months after the first use without significant performance degradation. Our method and device would help realizing continuous alcohol monitoring in the wearable platform.

An eight-channel correlation electron cyclotron emission diagnostic for turbulent electron temperature fluctuation measurement in HL-2A tokamak.

A new correlation electron cyclotron emission (CECE) diagnostic has recently been installed on the HL-2A tokamak in order to study electron temperature fluctuations. Eight radial locations are measured simultaneously through eight pairs of correlated channels. Multiplexers are employed in the intermediate frequency section instead of the conventional separated filter banks to meet strict cross-isolation specifications and lower insertion loss. Relative electron temperature fluctuations are observed by CECE for the first time on the HL-2A by using the spectral decorrelation method. The achieved minimum detectable fluctuation level is up to (T̃e/Te)min∼0.5%. When studying electron temperature fluctuations in the core region with gas puffing, the cross-power spectra show that the amplitude of the electron temperature fluctuation increases in a high temperature and low density plasma. Further analysis demonstrates that the electron temperature gradient ∇Te drives the electron temperature fluctuations together with electron heat transport.

Microarray immunoassay for thyrotropin on track-etched membranes using radiotracers

We report a microarray immunoassay for thyrotropin in serum using an anti-thyrotropin monoclonal ‘antibody-chip’ fabricated on polycarbonate track-etched membranes as a solid-support. The thyrotropin microarray immunoassay is an immunoradiometric assay using 125I tracer and requires very small volumes of sample and reagents. The microarray immunoassay had the required minimum detection level, intra- and inter-assay CV and working range to be clinically useful. It correlated very significantly with commercial immunoradiometric assays for thyrotropin. We developed this microarray immunoassay for thyrotropin since it is often used as the first line test for thyroid function.

Identification of Small Berry Species in Food and Juice Using TaqMan-Based Real-Time PCR.

Background: Public interest is growing for small berries in recent years because they are very delicious, low in energy, and full of bioactive compounds with potential health benefits. Similar to other food products, adulteration of small berry fruit products poses economic and safety problems to consumers. Objective: To protect consumers and regulate the small berry fruit products market, it is necessary to establish a robust method for detecting the authenticity. Methods: In this study, TaqMan-based real-time PCR assay was established for species identification of cranberry, raspberry, and blueberry to ensure authenticity of commercial small berry food products (pulp, dried fruit, fruit juice, jam, and puree). Results: Absolute detection limit was 0.1 pg/μL DNA for raspberries, 1 pg/μL DNA for blueberries, and 10 pg/μL DNA for cranberries. Practical LOD was 0.1% (v/v) for fresh juice. For processed juice, practical LOD was 1% for blueberry and red raspberries, 0.1% for black and yellow raspberries, and 5% for cranberry. Conclusions: The method was shown to be functional and effective to detect the raw material composition of cranberry, raspberry, and blueberry for commercial products. Highlights: TaqMan probe-based real-time PCR methods were designed to identify three small berries (blueberry, raspberry, and cranberry) in berry products. Efficient DNA recovery methods and detection strategy were established to ensure correct and sensitive testing of fresh small berries exhibited a detection limit of 0.1 to 10 pg/μL. The practical minimum detection levels were 0.1 to 5% in fresh and processed juice, including pasteurization and HTHP.