High-field modulated ion-selective field-effect-transistor (FET) sensors with sensitivity higher than the ideal Nernst sensitivity.

PubMed

Chen, Yi-Ting; Sarangadharan, Indu; Sukesan, Revathi; Hseih, Ching-Yen; Lee, Geng-Yen; Chyi, Jen-Inn; Wang, Yu-Lin

2018-05-29

Lead ion selective membrane (Pb-ISM) coated AlGaN/GaN high electron mobility transistors (HEMT) was used to demonstrate a whole new methodology for ion-selective FET sensors, which can create ultra-high sensitivity (-36 mV/log [Pb 2+ ]) surpassing the limit of ideal sensitivity (-29.58 mV/log [Pb 2+ ]) in a typical Nernst equation for lead ion. The largely improved sensitivity has tremendously reduced the detection limit (10 -10  M) for several orders of magnitude of lead ion concentration compared to typical ion-selective electrode (ISE) (10 -7  M). The high sensitivity was obtained by creating a strong filed between the gate electrode and the HEMT channel. Systematical investigation was done by measuring different design of the sensor and gate bias, indicating ultra-high sensitivity and ultra-low detection limit obtained only in sufficiently strong field. Theoretical study in the sensitivity consistently agrees with the experimental finding and predicts the maximum and minimum sensitivity. The detection limit of our sensor is comparable to that of Inductively-Coupled-Plasma Mass Spectrum (ICP-MS), which also has detection limit near 10 -10  M.

An adaptive confidence limit for periodic non-steady conditions fault detection

NASA Astrophysics Data System (ADS)

Wang, Tianzhen; Wu, Hao; Ni, Mengqi; Zhang, Milu; Dong, Jingjing; Benbouzid, Mohamed El Hachemi; Hu, Xiong

2016-05-01

System monitoring has become a major concern in batch process due to the fact that failure rate in non-steady conditions is much higher than in steady ones. A series of approaches based on PCA have already solved problems such as data dimensionality reduction, multivariable decorrelation, and processing non-changing signal. However, if the data follows non-Gaussian distribution or the variables contain some signal changes, the above approaches are not applicable. To deal with these concerns and to enhance performance in multiperiod data processing, this paper proposes a fault detection method using adaptive confidence limit (ACL) in periodic non-steady conditions. The proposed ACL method achieves four main enhancements: Longitudinal-Standardization could convert non-Gaussian sampling data to Gaussian ones; the multiperiod PCA algorithm could reduce dimensionality, remove correlation, and improve the monitoring accuracy; the adaptive confidence limit could detect faults under non-steady conditions; the fault sections determination procedure could select the appropriate parameter of the adaptive confidence limit. The achieved result analysis clearly shows that the proposed ACL method is superior to other fault detection approaches under periodic non-steady conditions.

Fiber type-specific analysis of AMPK isoforms in human skeletal muscle: advancement in methods via capillary nanoimmunoassay.

PubMed

Tobias, Irene S; Lazauskas, Kara K; Arevalo, Jose A; Bagley, James R; Brown, Lee E; Galpin, Andrew J

2018-04-01

Human skeletal muscle is a heterogeneous mixture of multiple fiber types (FT). Unfortunately, present methods for FT-specific study are constrained by limits of protein detection in single-fiber samples. These limitations beget compensatory resource-intensive procedures, ultimately dissuading investigators from pursuing FT-specific research. Additionally, previous studies neglected hybrid FT, confining their analyses to only pure FT. Here we present novel methods of protein detection across a wider spectrum of human skeletal muscle FT using fully automated capillary nanoimmunoassay (CNIA) technology. CNIA allowed a ~20-fold-lower limit of 5'-AMP-activated protein kinase (AMPK) detection compared with Western blotting. We then performed FT-specific assessment of AMPK expression as a proof of concept. Individual human muscle fibers were mechanically isolated, dissolved, and myosin heavy chain (MHC) fiber typed via SDS-PAGE. Single-fiber samples were combined in pairs and grouped into MHC I, MHC I/IIa, MHC IIa, and MHC IIa/IIx for expression analysis of AMPK isoforms α 1 , α 2 , β 1 , β 2 , γ 2 , and γ 3 with a tubulin loading control. Significant FT-specific differences were found for α 2 (1.7-fold higher in MHC IIa and MHC IIa/IIx vs. others), γ 2 (2.5-fold higher in MHC IIa vs. others), and γ 3 (2-fold higher in MHC IIa and 4-fold higher in MHC IIa/IIx vs. others). Development of a protocol that combines the efficient and sensitive CNIA technology with comprehensive SDS-PAGE fiber typing marks an important advancement in FT-specific research because it allows more precise study of the molecular mechanisms governing metabolism, adaptation, and regulation in human muscle. NEW & NOTEWORTHY We demonstrate the viability of applying capillary nanoimmunoassay technology to the study of fiber type-specific protein analysis in human muscle fibers. This novel technique enables a ~20-fold-lower limit of protein detection compared with traditional Western blotting methods. Combined with SDS-PAGE methods of fiber typing, we apply this technique to compare 5'-AMP-activated protein kinase isoform expression in myosin heavy chain (MHC) I, MHC I/IIa, MHC IIa, and MHC IIa/IIx fiber types.

IS HCI THAT IS USED AS A PRESERVATIVE CREATING FALSE POSITIVES FOR TBA IN GROUND WATER

EPA Science Inventory

Will hydrochloric acid produce false positives for TBA? Yes, if you heat the sample to get a lower detection limit for TBA. Conventional purge and trap methods at ambient temperature have a reporting limit for TBA between 50 and 100 g/liter. This is higher than the provisiona...

Level-Specific Evaluation of Model Fit in Multilevel Structural Equation Modeling

ERIC Educational Resources Information Center

Ryu, Ehri; West, Stephen G.

2009-01-01

In multilevel structural equation modeling, the "standard" approach to evaluating the goodness of model fit has a potential limitation in detecting the lack of fit at the higher level. Level-specific model fit evaluation can address this limitation and is more informative in locating the source of lack of model fit. We proposed level-specific test…

In-channel amperometric detection for microchip electrophoresis using a wireless isolated potentiostat

PubMed Central

Gunasekara, Dulan B.; Hulvey, Matthew K.; Lunte, Susan M.

2012-01-01

The combination of microchip electrophoresis (ME) with amperometric detection leads to a number of analytical challenges that are associated with isolating the detector from the high voltages used for the separation. While methods such as end-channel alignment and the use of decouplers have been employed, they have limitations. A less common method has been to utilize an electrically isolated potentiostat. This approach allows placement of the working electrode directly in the separation channel without using a decoupler. This paper explores the use of microchip electrophoresis and electrochemical detection (ME-EC) with an electrically isolated potentiostat for the separation and in-channel detection of several biologically important anions. The separation employed negative polarity voltages and tetradecyltrimethylammonium bromide (TTAB, as a buffer modifier) for the separation of nitrite (NO2-), glutathione (GSH), ascorbic acid (AA), and tyrosine (Tyr). A half-wave potential (E½) shift of approximately negative 500 mV was observed for NO2- and H2O2 standards in the in-channel configuration compared to end channel. Higher separation efficiencies were observed for both NO2- and H2O2 with the in-channel detection configuration. The limits of detection were approximately two-fold lower and the sensitivity was approximately two-fold higher for in-channel detection of nitrite when compared to end-channel. The application of this microfluidic device for the separation and detection of biomarkers related to oxidative stress is described. PMID:21437918

Two-dimensional on-line detection of brominated and iodinated volatile organic compounds by ECD and ICP-MS after GC separation.

PubMed

Schwarz, A; Heumann, K G

2002-09-01

Inductively coupled plasma-mass spectrometry (ICP-MS) was coupled to a gas chromatographic (GC) system with electron capture detector (ECD), which enables relatively easy characterization and quantification of brominated and iodinated (halogenated) volatile organic compounds (HVOCs) in aquatic and air samples. The GC-ECD system is connected in series with an ICP-MS by a directly heated transfer line and an outlet port-hole for elimination of the ECD make-up gas during ignition of the plasma. The hyphenated GC-ECD/ICP-MS system provides high selectivity and sensitivity for monitoring individual HVOCs under fast chromatographic conditions. The ECD is most sensitive for the detection of chlorinated and brominated but the ICP-MS for iodinated compounds. The greatest advantage of the use of an ICP-MS is its element-specific detection, which allows clear identification of compounds in most cases. The absolute detection limits for ICP-MS are 0.5 pg for iodinated, 10 pg for brominated, and 50 pg for chlorinated HVOCs with the additional advantage that calibration is almost independent on different compounds of the same halogen. In contrast to that detection limits for ECD vary for the different halogenated compounds and lie in the range of 0.03-11 pg. The two-dimensional GC-ECD/ICP-MS instrumentation is compared with electron impact mass spectrometry (EI-MS) and microwave induced plasma atomic emission detection (MIP-AED). Even if EI-MS has additional power in identifying unknown peaks by its scan mode, the detection limits are much higher compared with GC-ECD/ICP-MS, whereas the selective ion monitoring mode (SIM) reaches similar detection limits. The MIP-AED detection limits are at the same level as EI-MS in the scan mode.

Detection of 70 kDa heat shock protein in the saliva of dairy cows.

PubMed

Lamy, Elsa; Jurkovich, Viktor; Rodrigues, Lénia; Geraldo, Ana; Cachucho, Liliana; Silva, Flávio; Matos, Catarina; Capela E Silva, Fernando; Pinheiro, Cristina; Könyves, László; Bakony, Mikolt; Pereira, Alfredo

2017-08-01

This Research Communication describes, for the first time, the detection of HSP70 in saliva of dairy cows. Thermal stress is a major environmental stress that limits animal growth, metabolism, and productivity. The cellular response to heat stress involves the synthesis of heat shock proteins (HSPs), presumably to protect the functional stability of cells at increasing temperatures. HSP70 has been found to be present in cattle blood serum and may also be present in other secretory fluids, such as saliva, as already observed in humans. The aim of this study was to detect heat shock protein HSP70 in bovine saliva. Saliva samples were taken from higher- (n = 5) and lower milk producing (n = 5) Holstein-Friesian cows in summer and in winter for the detection of HSP70. HSP70 concentrations were assayed using the ELISA technique. Salivary HSP70 concentrations ranged from 0·524 to 12·174 ng/ml in cows. Higher salivary HSP70 concentrations were significantly associated with higher milk production and higher environmental temperature, but not with rectal temperature.

Detection of Xeljanz enantiomers in diethyl amine active pharmaceutical ingredients and tablets.

PubMed

Wang, Na-Na; Zhang, Dao-Lin; Jiang, Xin-Hui

2015-03-01

A high-performance liquid chromatography (HPLC) method was established to detect Xeljanz enantiomers in active pharmaceutical ingredients (APIs) and tablets. The separation was achieved on a Chiralpak IC column using a mobile phase of hexane-ethanol-diethylamine (65:35:0.1, v/v). The detection wavelength was 289 nm. The peak areas and the enantiomer concentrations in the range of 0.15-2.25 μg•mL(-1) were in high linearity, with correlation coefficients higher than 0.999. The recoveries were 86.44% at the concentrations of 7.5, 18.75, and 37.5 μg•mL(-1) . The limit of detection (LOD) and limit of quantification (LOQ) were 0.042 and 0.14 μg•mL(-1) , respectively. This HPLC method is suitable for detecting the enantiomers of Xeljanz in its APIs and tablets. © 2014 Wiley Periodicals, Inc.

A SQUID-based metal detector—comparison to coil and x-ray systems

NASA Astrophysics Data System (ADS)

Bick, M.; Sullivan, P.; Tilbrook, D. L.; Du, J.; Gnanarajan, S.; Leslie, K. E.; Foley, C. P.

2005-03-01

The presence of foreign metal bodies and fragments in foodstuff and pharmaceutical products is of major concern to producers. Further, hidden metal objects can pose threats to security. In particular, stainless steel is difficult to detect by conventional coil metal detectors due to its low conductivity. We have employed an HTS SQUID magnetometer for the detection of stainless steel particles which is based on the measurement of the remanent magnetization of the particle. Our aim was to determine the detection limits of HTS SQUID-based remote magnetometry, especially for food inspection purposes, and to make a comparison of this technique to commonly used eddy current coil and x-ray inspection systems. We show that the SQUID system's sensitivity to stainless steel fragments is significantly higher than that of coil systems if the samples are magnetized in a 100 mT magnetic field prior to detection. Further, it has a higher sensitivity than x-ray systems, depending on the density distribution of the product under inspection. A 0.6 mg piece of grade-316 stainless steel (a fragment of a hypodermic needle 0.5 mm long and 0.65 mm diameter) represents the detection limit of our system with a 150 × 150 mm2 inspection orifice.

High-energy photon interrogation for nonproliferation applications

NASA Astrophysics Data System (ADS)

Jones, J. L.; Blackburn, B. W.; Watson, S. M.; Norman, D. R.; Hunt, A. W.

2007-08-01

There is an immediate need for technologies that can successfully address homeland security challenges related to the inspection of commercial rail, air and maritime-cargo container inspections for nuclear and radiological devices. The pulsed photonuclear assessment (PPA) technology, developed through collaboration between Idaho National Laboratory (INL), Los Alamos National Laboratory (LANL) and the Idaho Accelerator Center (IAC) has demonstrated the ability to detect shielded/unshielded nuclear material primarily through the analysis of delayed neutrons and gamma-rays produced via photonuclear reactions. Because of current food irradiation limitations, however, most active photon (i.e. bremsstrahlung) interrogation studies have been performed with electron beam energies at or below 10 MeV. While this energy limit currently applies to cargo inspections, the World Health Organization has indicated that higher energy electron beam operations could be considered for future operations. Clinical applications using photon energies well in excess of 10 MeV are already well established. Notwithstanding the current limitation of 10 MeV, there is a definite advantage in using higher photon energies for cargo inspections. At higher energies, several phenomena contribute to increased sensitivity in regards to detecting shielded nuclear material. Two of the most important are: (1) increased ability for source photons to penetrate shielding; and (2) enhanced signature production via increased (γ,n) and (γ,f) cross-sections in materials such as 235U and 239Pu directly leading to faster inspection throughput. Experimental assessments have been conducted for various electron beam energies from 8 to 25 MeV. Increases of up to three orders of magnitude in delayed signatures have been measured over these energy ranges. Through the continued investigation into PPA-based inspection applications using photon energies greater than 10 MeV, higher detection sensitivities with potentially lower delivered dose to cargo and increased throughput may be realized.

Understanding Marine Biocorrosion: Experiments with Artificial and Natural Seawater

DTIC Science & Technology

2015-11-04

study of microbiologically infl uenced marine corrosion (MIMC) and the consideration of nutrients for microorganisms. Recent MIMC investigations have...conclusion of the experiment the concentration of sulphide was below the detection limit (Figure 13.3 ). Generally, KW seawater had higher numbers of...sulphides. Supporting their hypothesis, diagnostic catechols, which are known aerobic degradation products of hydrocarbons, were detected in the NRL

Higher Throughput Calorimetry: Opportunities, Approaches and Challenges

PubMed Central

Recht, Michael I.; Coyle, Joseph E.; Bruce, Richard H.

2010-01-01

Higher throughput thermodynamic measurements can provide value in structure-based drug discovery during fragment screening, hit validation, and lead optimization. Enthalpy can be used to detect and characterize ligand binding, and changes that affect the interaction of protein and ligand can sometimes be detected more readily from changes in the enthalpy of binding than from the corresponding free-energy changes or from protein-ligand structures. Newer, higher throughput calorimeters are being incorporated into the drug discovery process. Improvements in titration calorimeters come from extensions of a mature technology and face limitations in scaling. Conversely, array calorimetry, an emerging technology, shows promise for substantial improvements in throughput and material utilization, but improved sensitivity is needed. PMID:20888754

A high performance three-phase enzyme electrode based on superhydrophobic mesoporous silicon nanowire arrays for glucose detection.

PubMed

Xu, Chenlong; Song, Zhiqian; Xiang, Qun; Jin, Jian; Feng, Xinjian

2016-04-14

We describe here a high performance oxygen-rich three-phase enzyme electrode based on superhydrophobic mesoporous silicon nanowire arrays for glucose detection. We demonstrate that its linear detection upper limit is 30 mM, more than 15 times higher than that can be obtained on the normal enzyme-electrode. Notably, the three-phase enzyme electrode output is insensitive to the significant oxygen level fluctuation in analyte solution.

Evaluation of minerals content of drinking water in Malaysia.

PubMed

Azlan, Azrina; Khoo, Hock Eng; Idris, Mohd Aizat; Ismail, Amin; Razman, Muhammad Rizal

2012-01-01

The drinking and mineral water samples obtained from different geographical locations had concentrations of the selected minerals lower than the standard limits, except for manganese, arsenic, and fluoride. The concentrations of manganese and arsenic in two mineral water samples were slightly higher than the standard international recommended limits. One mineral water sample had a fluoride concentration higher than the standard limits, whereas manganese was not detected in nine drinking and mineral water samples. Most of the selected minerals found in the tap water samples were below the international standard limits, except for iron and manganese. The concentrations of iron and manganese in the tap water samples were higher than the standard limits, which were obtained from one and three of the studied locations, respectively. The potable water obtained from various manufacturers and locations in Peninsular Malaysia is safe for consumption, as the minerals concentrations were below the standard limits prescribed by the Malaysian Food Regulations of 1985. The data obtained may also provide important information related to daily intake of these minerals from drinking water.

Evaluation of Minerals Content of Drinking Water in Malaysia

PubMed Central

Azlan, Azrina; Khoo, Hock Eng; Idris, Mohd Aizat; Ismail, Amin; Razman, Muhammad Rizal

2012-01-01

The drinking and mineral water samples obtained from different geographical locations had concentrations of the selected minerals lower than the standard limits, except for manganese, arsenic, and fluoride. The concentrations of manganese and arsenic in two mineral water samples were slightly higher than the standard international recommended limits. One mineral water sample had a fluoride concentration higher than the standard limits, whereas manganese was not detected in nine drinking and mineral water samples. Most of the selected minerals found in the tap water samples were below the international standard limits, except for iron and manganese. The concentrations of iron and manganese in the tap water samples were higher than the standard limits, which were obtained from one and three of the studied locations, respectively. The potable water obtained from various manufacturers and locations in Peninsular Malaysia is safe for consumption, as the minerals concentrations were below the standard limits prescribed by the Malaysian Food Regulations of 1985. The data obtained may also provide important information related to daily intake of these minerals from drinking water. PMID:22649292

Comparison of MTBE concentrations in groundwater of urban and nonurban areas in Germany.

PubMed

Kolb, Axel; Püttmann, Wilhelm

2006-11-01

The occurrence of the gasoline oxygenate methyl tert-butyl ether (MTBE) in groundwater samples from known fuel-contaminated sites (n=29 samples), nonurban (n=74) and urban sites (n=67) in Germany was investigated. The analyses revealed detection frequencies of 58% (contaminated sites), 24% (nonurban sites) and 63% (urban sites) at a detection limit of 0.01 microgL(-1). Median (maximum) MTBE concentrations were calculated for nonurban and urban samples as 0.18 microgL(-1) (2.2 microgL(-1)) and 0.06 microgL(-1) (48 microg L(-1)). The data from nonurban samples revealed MTBE detections mainly at public supply wells with higher pumping rates than monitoring wells. MTBE was more frequently detected in urban samples, most probably due to the higher atmospheric input and direct liquid emissions from motorways or gas stations. Higher concentrations above 1.0 microgL(-1) in urban areas were found in wells located at industrial sites, where also a MTBE plume was accidentally detected during the study. The prevalence of MTBE in shallow aquifers was comparable to those in the USA.

Physiological comparisons of plasma and tissue metrics of selected inland and coastal steelhead kelts.

USGS Publications Warehouse

Penney, Zachary L.; Moffitt, Christine M.; Jones, Bryan; Marston, Brian

2016-01-01

The physiological status of migrating steelhead kelts (Oncorhynchus mykiss) from the Situk River, Alaska, and two tributaries of the Clearwater River, Idaho, was evaluated to explore potential differences in post-spawning survival related to energy reserves. Blood plasma samples were analyzed for metrics related to nutritional and osmotic status, and samples of white muscle tissue collected from recent mortalities at weirs were analyzed for proximate constituents. Female kelts from the Situk River had significantly higher plasma cholesterol, triglycerides, glucose and calcium concentrations, all of which suggested higher lipid and energy stores. Additional support for energy limitation in kelts was provided by evaluating the presence of detectable proteins in the plasma. Most all kelts sampled from the Situk River populations had detectable plasma proteins, in contrast to kelts sampled from the Clearwater River tributary populations where 27 % of kelts from one tributary, and 68 % of the second tributary were below the limits of detection. We found proximate constituents of kelt mortalities were similar between the Situk and Clearwater River populations, and the lipid fraction of white muscle averaged 0.1 and 0.2 %. Our findings lend support to the hypothesis that energetic limitations likely affect post-spawn survival in the Clearwater River kelts.

Comparison of detection limit in fiber-based conventional, amplified, and gain-clamped cavity ring-down techniques

NASA Astrophysics Data System (ADS)

Sharma, K.; Abdul Khudus, M. I. M.; Alam, S. U.; Bhattacharya, S.; Venkitesh, D.; Brambilla, G.

2018-01-01

Relative performance and detection limit of conventional, amplified, and gain-clamped cavity ring-down techniques (CRDT) in all-fiber configurations are compared experimentally for the first time. Refractive index measurement using evanescent field in tapered fibers is used as a benchmark for the comparison. The systematic optimization of a nested-loop configuration in gain-clamped CRDT is also discussed, which is crucial for achieving a constant gain in a CRDT experiment. It is found that even though conventional CRDT has the lowest standard error in ring-down time (Δτ), the value of ring-down time (τ) is very small, thus leading to poor detection limit. Amplified CRDT provides an improvement in τ, albeit with two orders of magnitude higher Δτ due to amplifier noise. The nested-loop configuration in gain-clamped CRDT helps in reducing Δτ by an order of magnitude as compared to amplified CRDT whilst retaining the improvement in τ. A detection limit of 1 . 03 × 10-4 RIU at refractive index of 1.322 with a 3 mm long and 4.5 μm diameter tapered fiber is demonstrated with the gain-clamped CRDT.

Improved method for the on-line metal chelate affinity chromatography-high-performance liquid chromatographic determination of tetracycline antibiotics in animal products.

PubMed

Cooper, A D; Stubbings, G W; Kelly, M; Tarbin, J A; Farrington, W H; Shearer, G

1998-07-03

An improved on-line metal chelate affinity chromatography-high-performance liquid chromatography (MCAC-HPLC) method for the determination of tetracycline antibiotics in animal tissues and egg has been developed. Extraction was carried out with ethyl acetate. The extract was then evaporated to dryness and reconstituted in methanol prior to on-line MCAC clean-up and HPLC-UV determination. Recoveries of tetracycline, oxytetracycline, demeclocycline and chlortetracycline in the range 42% to 101% were obtained from egg, poultry, fish and venison tissues spiked at 25 micrograms kg-1. Limits of detection less than 10 microgram kg-1 were estimated for all four analytes. This method has higher throughput, higher recovery and lower limits of detection than a previously reported on-line MCAC-HPLC method which involved aqueous extraction and solid-phase extraction clean-up.

Solar atmospheric neutrinos: A new neutrino floor for dark matter searches

NASA Astrophysics Data System (ADS)

Ng, Kenny C. Y.; Beacom, John F.; Peter, Annika H. G.; Rott, Carsten

2017-11-01

As is well known, dark matter direct detection experiments will ultimately be limited by a "neutrino floor," due to the scattering of nuclei by MeV neutrinos from, e.g., nuclear fusion in the Sun. Here we point out the existence of a new neutrino floor that will similarly limit indirect detection with the Sun, due to high-energy neutrinos from cosmic-ray interactions with the solar atmosphere. We have two key findings. First, solar atmospheric neutrinos ≲1 TeV cause a sensitivity floor for standard weakly interacting massive particles (WIMP) scenarios, for which higher-energy neutrinos are absorbed in the Sun. This floor will be reached once the present sensitivity is improved by just 1 order of magnitude. Second, for neutrinos ≳1 TeV , which can be isolated by muon energy loss rate, solar atmospheric neutrinos should soon be detectable in IceCube. Discovery will help probe the complicated effects of solar magnetic fields on cosmic rays. These events will be backgrounds to WIMP scenarios with long-lived mediators, for which higher-energy neutrinos can escape from the Sun.

Peptide Functionalized Gold Nanorods for the Sensitive Detection of a Cardiac Biomarker Using Plasmonic Paper Devices (Postprint)

DTIC Science & Technology

2015-11-10

valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YY) 2. REPORT TYPE 3 . DATES COVERED (From...refractive index difference on the order of 3 × 10−4 refractive index units (RIU)), probe the conformational changes of individual biomacromolecules, detect...natural antibodies and short peptides, as BREs. We demonstrate that pep - tides provide a significantly higher sensitivity and lower limit of detection

Occurrence and concentrations of pharmaceutical compounds in deep groundwater used for public drinking-water supply in California

USGS Publications Warehouse

Fram, Miranda S.; Belitz, Kenneth

2011-01-01

Pharmaceutical compounds were detected at low concentrations in 2.3% of 1231 samples of groundwater (median depth to top of screened interval in wells = 61 m) used for public drinking-water supply in California. Samples were collected statewide for the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program. Of 14 pharmaceutical compounds analyzed, 7 were detected at concentrations greater than or equal to method detection limits: acetaminophen (used as an analgesic, detection frequency 0.32%, maximum concentration 1.89 μg/L), caffeine (stimulant, 0.24%, 0.29 μg/L), carbamazepine (mood stabilizer, 1.5%, 0.42 μg/L), codeine (opioid analgesic, 0.16%, 0.214 μg/L), p-xanthine (caffeine metabolite, 0.08%, 0.12 μg/L), sulfamethoxazole (antibiotic, 0.41%, 0.17 μg/L), and trimethoprim (antibiotic, 0.08%, 0.018 μg/L). Detection frequencies of pesticides (33%), volatile organic compounds not including trihalomethanes (23%), and trihalomethanes (28%) in the same 1231 samples were significantly higher. Median detected concentration of pharmaceutical compounds was similar to those of volatile organic compounds, and higher than that of pesticides. Pharmaceutical compounds were detected in 3.3% of the 855 samples containing modern groundwater (tritium activity > 0.2 TU). Pharmaceutical detections were significantly positively correlated with detections of urban-use herbicides and insecticides, detections of volatile organic compounds, and percentage of urban land use around wells. Groundwater from the Los Angeles metropolitan area had higher detection frequencies of pharmaceuticals and other anthropogenic compounds than groundwater from other areas of the state with similar proportions of urban land use. The higher detection frequencies may reflect that groundwater flow systems in Los Angeles area basins are dominated by engineered recharge and intensive groundwater pumping.

Augmented Reality for Real-Time Detection and Interpretation of Colorimetric Signals Generated by Paper-Based Biosensors.

PubMed

Russell, Steven M; Doménech-Sánchez, Antonio; de la Rica, Roberto

2017-06-23

Colorimetric tests are becoming increasingly popular in point-of-need analyses due to the possibility of detecting the signal with the naked eye, which eliminates the utilization of bulky and costly instruments only available in laboratories. However, colorimetric tests may be interpreted incorrectly by nonspecialists due to disparities in color perception or a lack of training. Here we solve this issue with a method that not only detects colorimetric signals but also interprets them so that the test outcome is understandable for anyone. It consists of an augmented reality (AR) app that uses a camera to detect the colored signals generated by a nanoparticle-based immunoassay, and that yields a warning symbol or message when the concentration of analyte is higher than a certain threshold. The proposed method detected the model analyte mouse IgG with a limit of detection of 0.3 μg mL -1 , which was comparable to the limit of detection afforded by classical densitometry performed with a nonportable device. When adapted to the detection of E. coli, the app always yielded a "hazard" warning symbol when the concentration of E. coli in the sample was above the infective dose (10 6 cfu mL -1 or higher). The proposed method could help nonspecialists make a decision about drinking from a potentially contaminated water source by yielding an unambiguous message that is easily understood by anyone. The widespread availability of smartphones along with the inexpensive paper test that requires no enzymes to generate the signal makes the proposed assay promising for analyses in remote locations and developing countries.

Experimental Demonstration of Higher Precision Weak-Value-Based Metrology Using Power Recycling

NASA Astrophysics Data System (ADS)

Wang, Yi-Tao; Tang, Jian-Shun; Hu, Gang; Wang, Jian; Yu, Shang; Zhou, Zong-Quan; Cheng, Ze-Di; Xu, Jin-Shi; Fang, Sen-Zhi; Wu, Qing-Lin; Li, Chuan-Feng; Guo, Guang-Can

2016-12-01

The weak-value-based metrology is very promising and has attracted a lot of attention in recent years because of its remarkable ability in signal amplification. However, it is suggested that the upper limit of the precision of this metrology cannot exceed that of classical metrology because of the low sample size caused by the probe loss during postselection. Nevertheless, a recent proposal shows that this probe loss can be reduced by the power-recycling technique, and thus enhance the precision of weak-value-based metrology. Here we experimentally realize the power-recycled interferometric weak-value-based beam-deflection measurement and obtain the amplitude of the detected signal and white noise by discrete Fourier transform. Our results show that the detected signal can be strengthened by power recycling, and the power-recycled weak-value-based signal-to-noise ratio can surpass the upper limit of the classical scheme, corresponding to the shot-noise limit. This work sheds light on higher precision metrology and explores the real advantage of the weak-value-based metrology over classical metrology.

[Survey on fungi contamination and natural occurrence of mycotoxins in 94 corn feed ingredients collected from China].

PubMed

Han, X M; Zhang, H Y; Zhang, J; Xu, W J; Liu, D; Jiang, T; Xu, J; Li, F Q

2016-10-06

Objective: To investigate fungi contamination and the natural occurrence of mycotoxins in corn feed ingredients collected from China. Methods: A total of 94 corn feed ingredient samples were collected from 8 Chinese provinces(i.e., Anhui, Hebei, Heilongjiang, Jilin, Jiangsu, Liaoning, Inner Mongolia, and Shandong)in February 2014. A tandem ultra-performance liquid chromatographymass spectrometry method was used for simultaneous detection of twelve kinds of mycotoxins, including aflatoxin(AF), type A and type B tricothecenes, and zearalenone(ZEN). Contaminated fungi were also identified and counted. Results: AF was detected in 36.2%(34/94)of samples; the concentration of AFB 1 was the highest in the four AFs with the range: 0.3~181.3 μg/kg; and then followed by AFB 2 (range: 1.0-74.3 μg/kg). There were 7 samples(7.5%)with AFB 1 concentrations higher than the tolerance limit of 50 μg/kg. The concentration of type A tricothecenes in all samples was lower(0.1-10.5 μg/kg). DON had the most serious contamination than other kind of type B tricothecenes(range: 0.7-606.6 μg/kg; median: 66.3 μg/kg). The DON concentration in all samples was below the tolerance limit of 1 000 μg/kg. ZEN was detected in 76.6%(72/ 94)of samples(median: 36.9 μg/kg), with 3 samples having ZEN concentrations higher than the tolerance limit of 500 μg/kg. The survey on fungi contamination showed that all samples were contaminated by fungi(range: 5.0-1.4×10 5 CFU/g). There were 18 and 3 samples with quantities of fungi higher than the tolerance and forbidden limits, respectively. The Aspergillus , Penicillium , Fusarium , Trichoderma and Mucor genuses were the predominant fungi in corn feed ingredients, with detection rates of 71.3%(67), 60.6%(57), 71.3%(67), 27.7%(26), and 24.5%(23), respectively. The detection rate of Fusarium moniliforme , 73.4%(69/94)was higher than that of Aspergillus flavus , 41.5%(39/94). Conclusion: In this survey, the corn feed ingredients were not seriously contaminated by AF and type A tricothecenes but mainly contaminated by type B trichothecenes, including DON and its derivatives, as well as ZEN. They were also contaminated by fungi such as Aspergillus , Penicillium , and Fusarium .

Design, fabrication, and optimization of photo acoustic gas sensor for the trace level detection of NO2 in the atmosphere.

PubMed

Gondal, Mohammed A; Dastageer, Mohamed A

2010-09-01

Photoacoustic (PA) gas sensor for the detection of hazardous NO(2) with detection limit as low as few part per billion by volume (ppbV) has been designed and tested with pulsed UV laser. Some design optimization factors such as the optimum cell geometry, buffer gas etc has been proposed. It was found that a cylindrical cell with many acoustic filters considerably dampens the noise level and also argon as a buffer gas improves the photoacoustic signal level and this combination substantially improved the signal to noise ratio and the limit of detection. Ambiguous decline of photo acoustic signal at higher NO(2) concentration due to the adsorption of NO(2) on the walls of the photoacoustic cells and the dependence of this effect on the buffer gases are also discussed. The PA signal dependence on incident laser energy for three cells was also investigated.

Lowering detection limits for 1,2,3-trichloropropane in water using solid phase extraction coupled to purge and trap sample introduction in an isotope dilution GC-MS method.

PubMed

Liao, Wenta; Ghabour, Miriam; Draper, William M; Chandrasena, Esala

2016-09-01

Purge and trap sample introduction (PTI) has been the premier sampling and preconcentration technique for gas chromatographic determination of volatile organic compounds (VOCs) in drinking water for almost 50 years. PTI affords sub parts-per-billion (ppb) detection limits for purgeable VOCs including fixed gases and higher boiling hydrocarbons and halocarbons. In this study the coupling of solid phase extraction (SPE) to PTI was investigated as a means to substantially increase enrichment and lower detection limits for the emerging contaminant, 1,2,3-trichloropropane (TCP). Water samples (500 mL) were dechlorinated, preserved with a biocide, and spiked with the isotope labeled internal standard, d5-TCP. The entire 500 mL sample was extracted with activated carbon or carbon molecular sieve SPE cartridges, and then eluted with dichloromethane -- excess solvent was removed in a nitrogen evaporator and diethylene glycol "keeper" remaining was dispersed in 5 mL of water for PTI GC-MS analysis. The experimental Method Detection Limit (MDL) for TCP was 0.11 ng/L (ppt) and accuracy was 95-103% in sub-ppt determinations. Groundwater samples including impaired California sources and treated water (n = 21) were analyzed with results ranging from below the method reporting limit (0.30 ng/L) to > 250 ng/L. Coupling of SPE with PTI may provide similar reductions in detection limits for other VOCs with appropriate physical-chemical properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Health-hazard evaluation report HETA 87-063-1808, Presbyterian Day Surgery Center, Albuquerque, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniels, W.J.; Gunter, B.

1987-07-01

In response to a request from employees to evaluate exposures to waste anesthetic gases and vapors at the Presbyterian Day Surgery Unit, located in Albuquerque, New Mexico, personal and area air-sampling and leak-detection testing was carried out for nitrous oxide (N/sub 2/O) and halogenated anesthetic agents in the six operating rooms at the facility. Nitrous oxide concentrations ranged from not detectable to 95 parts per million (ppm) with a mean of 20ppm. Five of the samples exceeded the NIOSH limit of 25ppm for N/sub 2/O during anesthetic administration. Ethrane levels in 14 personal and area air samples ranged from lessmore » than the limit of detection to 3.63ppm with a mean of 0.31ppm. Isoflurane and halothane were below the limits of detection. The ventilation system in use changed the air in excess of 20 times per hour. However, during a portion of surgical procedures the system was not operating, resulting in a higher than normal exposure level in three of the operating rooms.« less

Colorimetric detection of cholesterol based on enzyme modified gold nanoparticles

NASA Astrophysics Data System (ADS)

Nirala, Narsingh R.; Saxena, Preeti S.; Srivastava, Anchal

2018-02-01

We develop a simple colorimetric method for determination of free cholesterol in aqueous solution based on functionalized gold nanoparticles with cholesterol oxidase. Functionalized gold nanoparticles interact with free cholesterol to produce H2O2 in proportion to the level of cholesterol visually is being detected. The quenching in optical properties and agglomeration of functionalized gold nanoparticles play a key role in cholesterol sensing due to the electron accepting property of H2O2. While the lower ranges of cholesterol (lower detection limit i.e. 0.2 mg/dL) can be effectively detected using fluorescence study, the absorption study attests evident visual color change which becomes effective for detection of higher ranges of cholesterol (lower detection limit i.e. 19 mg/dL). The shades of red gradually change to blue/purple as the level of cholesterol detected (as evident at 100 mg/dL) using unaided eye without the use of expensive instruments. The potential of the proposed method to be applied in the field is shown by the proposed cholesterol measuring color wheel.

Comparison of direct and heterodyne detection optical intersatellite communication links

NASA Technical Reports Server (NTRS)

Chen, C. C.; Gardner, C. S.

1987-01-01

The performance of direct and heterodyne detection optical intersatellite communication links are evaluated and compared. It is shown that the performance of optical links is very sensitive to the pointing and tracking errors at the transmitter and receiver. In the presence of random pointing and tracking errors, optimal antenna gains exist that will minimize the required transmitter power. In addition to limiting the antenna gains, random pointing and tracking errors also impose a power penalty in the link budget. This power penalty is between 1.6 to 3 dB for a direct detection QPPM link, and 3 to 5 dB for a heterodyne QFSK system. For the heterodyne systems, the carrier phase noise presents another major factor of performance degradation that must be considered. In contrast, the loss due to synchronization error is small. The link budgets for direct and heterodyne detection systems are evaluated. It is shown that, for systems with large pointing and tracking errors, the link budget is dominated by the spatial tracking error, and the direct detection system shows a superior performance because it is less sensitive to the spatial tracking error. On the other hand, for systems with small pointing and tracking jitters, the antenna gains are in general limited by the launch cost, and suboptimal antenna gains are often used in practice. In which case, the heterodyne system has a slightly higher power margin because of higher receiver sensitivity.

Occurrence of pesticides in surface water and sediments from three central California coastal watersheds, 2008-2009

USGS Publications Warehouse

Smalling, Kelly L.; Orlando, James L.

2011-01-01

Water and sediment (bed and suspended) were collected from January 2008 through October 2009 from 12 sites in 3 of the largest watersheds along California's Central Coast (Pajaro, Salinas, and Santa Maria Rivers) and analyzed for a suite of pesticides by the U.S. Geological Survey. Water samples were collected in each watershed from the estuaries and major tributaries during 4 storm events and 11 dry season sampling events in 2008 and 2009. Bed sediments were collected from depositional zones at the tributary sampling sites three times over the course of the study. Suspended sediment samples were collected from the major tributaries during the four storm events and in the tributaries and estuaries during three dry season sampling events in 2009. Water samples were analyzed for 68 pesticides using gas chromatography/mass spectrometry. A total of 38 pesticides were detected in 144 water samples, and 13 pesticides were detected in more than half the samples collected over the course of the study. Dissolved pesticide concentrations ranged from below their method detection limits to 36,000 nanograms per liter (boscalid). The most frequently detected pesticides in water from all the watersheds were azoxystrobin, boscalid, chlorpyrifos, DCPA, diazinon, oxyfluorfen, prometryn, and propyzamide, which were found in more than 80 percent of the samples. On average, detection frequencies and concentrations were higher in samples collected during winter storm events compared to the summer dry season. With the exception of the fungicide, myclobutanil, the Santa Maria estuary watershed exhibited higher pesticide detection frequencies than the Pajaro and Salinas watersheds. Bed and suspended sediment samples were analyzed for 55 pesticides using accelerated solvent extraction, gel permeation chromatography for sulfur removal, and carbon/alumina stacked solid-phase extraction cartridges to remove interfering sediment matrices. In bed sediment samples, 17 pesticides were detected including pyrethroid and organophosphate (OP) insecticides, p,p'-DDT and its degradates, as well as several herbicides. The only pesticides detected more than half the time were p,p'-DDD, p,p'-DDE, and p,p'-DDT. Maximum pesticide concentrations ranged from less than their respective method detection limits to 234 micrograms per kilogram (p,p'-DDE). Four pyrethroids (bifenthrin, &# 955;-cyhalothrin, permethrin, and &# 964;-fluvalinate) were detected in bed sediment samples, though concentrations were relatively low (less than 10 microgram per kilogram). The greatest number of pesticides were detected in samples collected from Lower Orcutt Creek, the major tributary to the Santa Maria estuary. In suspended sediment samples, 19 pesticides were detected, and maximum concentrations ranged from less than the method detection limits to 549 micrograms per kilogram (chlorpyrifos). The most frequently detected pesticides were p,p'-DDE (49 percent), p,p'-DDT (38 percent), and chlorpyrifos (32 percent). During storm events, 19 pesticides were detected in suspended sediment samples compared to 10 detected during the dry season. Pesticide concentrations commonly were higher in suspended sediments during storm events than during the dry season, as well.

Limits on fast radio bursts at 145 MHz with ARTEMIS, a real-time software backend

NASA Astrophysics Data System (ADS)

Karastergiou, A.; Chennamangalam, J.; Armour, W.; Williams, C.; Mort, B.; Dulwich, F.; Salvini, S.; Magro, A.; Roberts, S.; Serylak, M.; Doo, A.; Bilous, A. V.; Breton, R. P.; Falcke, H.; Grießmeier, J.-M.; Hessels, J. W. T.; Keane, E. F.; Kondratiev, V. I.; Kramer, M.; van Leeuwen, J.; Noutsos, A.; Osłowski, S.; Sobey, C.; Stappers, B. W.; Weltevrede, P.

2015-09-01

Fast radio bursts (FRBs) are millisecond radio signals that exhibit dispersion larger than what the Galactic electron density can account for. We have conducted a 1446 h survey for FRBs at 145 MHz, covering a total of 4193 deg2 on the sky. We used the UK station of the low frequency array (LOFAR) radio telescope - the Rawlings Array - accompanied for a majority of the time by the LOFAR station at Nançay, observing the same fields at the same frequency. Our real-time search backend, Advanced Radio Transient Event Monitor and Identification System - ARTEMIS, utilizes graphics processing units to search for pulses with dispersion measures up to 320 cm-3 pc. Previous derived FRB rates from surveys around 1.4 GHz, and favoured FRB interpretations, motivated this survey, despite all previous detections occurring at higher dispersion measures. We detected no new FRBs above a signal-to-noise threshold of 10, leading to the most stringent upper limit yet on the FRB event rate at these frequencies: 29 sky-1 d-1 for five ms-duration pulses above 62 Jy. The non-detection could be due to scatter-broadening, limitations on the volume and time searched, or the shape of FRB flux density spectra. Assuming the latter and that FRBs are standard candles, the non-detection is compatible with the published FRB sky rate, if their spectra follow a power law with frequency (∝ να), with α ≳ +0.1, demonstrating a marked difference from pulsar spectra. Our results suggest that surveys at higher frequencies, including the low frequency component of the Square Kilometre Array, will have better chances to detect, estimate rates and understand the origin and properties of FRBs.

Detecting submerged bodies: controlled research using side-scan sonar to detect submerged proxy cadavers.

PubMed

Healy, Carrie A; Schultz, John J; Parker, Kenneth; Lowers, Bim

2015-05-01

Forensic investigators routinely deploy side-scan sonar for submerged body searches. This study adds to the limited body of literature by undertaking a controlled project to understand how variables affect detection of submerged bodies using side-scan sonar. Research consisted of two phases using small and medium-sized pig (Sus scrofa) carcasses as proxies for human bodies to investigate the effects of terrain, body size, frequency, swath width, and state of decomposition. Results demonstrated that a clear, flat, sandy pond floor terrain was optimal for detection of the target as irregular terrain and/or vegetation are major limitations that can obscure the target. A higher frequency towfish was preferred for small bodies, and a 20 m swath width allowed greater visibility and easier maneuverability of the boat in this environment. Also, the medium-sized carcasses were discernable throughout the 81-day study period, indicating that it is possible to detect bodies undergoing decomposition with side-scan sonar. © 2015 American Academy of Forensic Sciences.

Ultra trace determination of 31 pesticides in water samples by direct injection-rapid resolution liquid chromatography-electrospray tandem mass spectrometry.

PubMed

Díaz, Laura; Llorca-Pórcel, Julio; Valor, Ignacio

2008-08-22

A liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method for the detection of pesticides in tap and treated wastewater was developed and validated according to the ISO/IEC 17025:1999. Key features of this method include direct injection of 100 microL of sample, an 11 min separation by means of a rapid resolution liquid chromatography system with a 4.6 mm x 50 mm, 1.8 microm particle size reverse phase column and detection by electrospray ionization (ESI) MS-MS. The limits of detection were below 15 ng L(-1) and correlation coefficients for the calibration curves in the range of 30-2000 ng L(-1) were higher than 0.99. Precision was always below 20% and accuracy was confirmed by external evaluation. The main advantages of this method are direct injection of sample without preparative procedures and low limits of detection that fulfill the requirements established by the current European regulations governing pesticide detection.

Stimulated Raman spectroscopy and nanoscopy of molecules using near field photon induced forces without resonant electronic enhancement gain

NASA Astrophysics Data System (ADS)

Tamma, Venkata Ananth; Huang, Fei; Nowak, Derek; Kumar Wickramasinghe, H.

2016-06-01

We report on stimulated Raman spectroscopy and nanoscopy of molecules, excited without resonant electronic enhancement gain, and recorded using near field photon induced forces. Photon-induced interaction forces between the sharp metal coated silicon tip of an Atomic Force Microscope (AFM) and a sample resulting from stimulated Raman excitation were detected. We controlled the tip to sample spacing using the higher order flexural eigenmodes of the AFM cantilever, enabling the tip to come very close to the sample. As a result, the detection sensitivity was increased compared with previous work on Raman force microscopy. Raman vibrational spectra of azobenzene thiol and l-phenylalanine were measured and found to agree well with published results. Near-field force detection eliminates the need for far-field optical spectrometer detection. Recorded images show spatial resolution far below the optical diffraction limit. Further optimization and use of ultrafast pulsed lasers could push the detection sensitivity towards the single molecule limit.

Stimulated Raman spectroscopy and nanoscopy of molecules using near field photon induced forces without resonant electronic enhancement gain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamma, Venkata Ananth; Huang, Fei; Kumar Wickramasinghe, H., E-mail: hkwick@uci.edu

We report on stimulated Raman spectroscopy and nanoscopy of molecules, excited without resonant electronic enhancement gain, and recorded using near field photon induced forces. Photon-induced interaction forces between the sharp metal coated silicon tip of an Atomic Force Microscope (AFM) and a sample resulting from stimulated Raman excitation were detected. We controlled the tip to sample spacing using the higher order flexural eigenmodes of the AFM cantilever, enabling the tip to come very close to the sample. As a result, the detection sensitivity was increased compared with previous work on Raman force microscopy. Raman vibrational spectra of azobenzene thiol andmore » l-phenylalanine were measured and found to agree well with published results. Near-field force detection eliminates the need for far-field optical spectrometer detection. Recorded images show spatial resolution far below the optical diffraction limit. Further optimization and use of ultrafast pulsed lasers could push the detection sensitivity towards the single molecule limit.« less

Diffusion related isotopic fractionation effects with one-dimensional advective-dispersive transport.

PubMed

Xu, Bruce S; Lollar, Barbara Sherwood; Passeport, Elodie; Sleep, Brent E

2016-04-15

Aqueous phase diffusion-related isotope fractionation (DRIF) for carbon isotopes was investigated for common groundwater contaminants in systems in which transport could be considered to be one-dimensional. This paper focuses not only on theoretically observable DRIF effects in these systems but introduces the important concept of constraining "observable" DRIF based on constraints imposed by the scale of measurements in the field, and on standard limits of detection and analytical uncertainty. Specifically, constraints for the detection of DRIF were determined in terms of the diffusive fractionation factor, the initial concentration of contaminants (C0), the method detection limit (MDL) for isotopic analysis, the transport time, and the ratio of the longitudinal mechanical dispersion coefficient to effective molecular diffusion coefficient (Dmech/Deff). The results allow a determination of field conditions under which DRIF may be an important factor in the use of stable carbon isotope measurements for evaluation of contaminant transport and transformation for one-dimensional advective-dispersive transport. This study demonstrates that for diffusion-dominated transport of BTEX, MTBE, and chlorinated ethenes, DRIF effects are only detectable for the smaller molar mass compounds such as vinyl chloride for C0/MDL ratios of 50 or higher. Much larger C0/MDL ratios, corresponding to higher source concentrations or lower detection limits, are necessary for DRIF to be detectable for the higher molar mass compounds. The distance over which DRIF is observable for VC is small (less than 1m) for a relatively young diffusive plume (<100years), and DRIF will not easily be detected by using the conventional sampling approach with "typical" well spacing (at least several meters). With contaminant transport by advection, mechanical dispersion, and molecular diffusion this study suggests that in field sites where Dmech/Deff is larger than 10, DRIF effects will likely not be observable for common groundwater contaminants. Importantly, under most field conditions, Dmech/Deff≥10 is usually satisfied in the longitudinal direction, suggesting that DRIF is not likely to be observable in most groundwater systems in which contaminant transport is predominantly one-dimensional. Given the importance in the MDL it is recommended that MDL should always be explicitly reported in both modeling and field studies. Copyright © 2016. Published by Elsevier B.V.

Wavelet-based higher-order neural networks for mine detection in thermal IR imagery

NASA Astrophysics Data System (ADS)

Baertlein, Brian A.; Liao, Wen-Jiao

2000-08-01

An image processing technique is described for the detection of miens in RI imagery. The proposed technique is based on a third-order neural network, which processes the output of a wavelet packet transform. The technique is inherently invariant to changes in signature position, rotation and scaling. The well-known memory limitations that arise with higher-order neural networks are addressed by (1) the data compression capabilities of wavelet packets, (2) protections of the image data into a space of similar triangles, and (3) quantization of that 'triangle space'. Using these techniques, image chips of size 28 by 28, which would require 0(109) neural net weights, are processed by a network having 0(102) weights. ROC curves are presented for mine detection in real and simulated imagery.

Microbial limitation in a changing world: A stoichiometric approach for predicting microbial resource limitation and fluxes

NASA Astrophysics Data System (ADS)

Midgley, M.; Phillips, R.

2014-12-01

Microbes mediate fluxes of carbon (C), nitrogen (N), and phosphorus (P) in soils depending on ratios of available C, N, and P relative to microbial demand. Hence, characterizing microbial C and nutrient limitation in soils is critical for predicting how ecosystems will respond to human alterations of climate and nutrient availability. Here, we take a stoichiometric approach to assessing microbial C, N, and P limitation by using threshold element ratios (TERs). TERs enable shifting resource limitation to be assessed by matching C, N and P ratios from microbial biomass, extracellular enzyme activities, and soil nutrient concentrations. We assessed microbial nutrient limitation in temperate forests dominated by trees that associate with one of two mycorrhizal symbionts: arbsucular mycorrhizal (AM) or ectomycorrhizal (ECM) fungi. We found that both ECM and AM microbial communities were co-limited by C and N, supporting conventional wisdom that microbes are C-limited and temperate forests are N-limited. However, AM microbial communities were relatively more C-limited than ECM communities (P=0.001). In response to chronic field N fertilization, both AM and ECM communities became relatively more P-limited (P=0.011), but they remained N- and C-limited overall. Thus, realistic levels of N deposition may not dampen microbial N limitation. Reflecting differences in relative limitation, N mineralization rates were higher in AM soils than in ECM soils (P=0.004) while C mineralization rates were higher in ECM soils than in AM soils (P=0.023). There were no significant differences in P flux between AM and ECM soils or detectable mineralization responses to N addition, indicating that mineralization rates are closely tied to C and nutrient limitation. Overall, we found that 1) microbial resource limitation can be detected without resource addition; and 2) TERs and ratios of labile resources are viable tools for predicting mineralization responses to resource additions.

A novel fluorescence-quenching immunochromatographic sensor for detection of the heavy metal chromium.

PubMed

Fu, QiangQiang; Tang, Yong; Shi, CongYing; Zhang, XiaoLi; Xiang, JunJian; Liu, Xi

2013-11-15

A novel fluorescence quenching immunochromatographic sensor (ICS) was developed for detecting chromium (Cr(3+)) within 15 min utilizing the fluorescence quenching function of gold nanoparticles (Au-NPs). The sensor performed with a positive readout. When the low concentrations of Cr(3+) samples were applied, detection signals of the test line (T line) were quenched, whereas when higher concentration Cr(3+) samples (1.56 ng/mL) were applied, the detection signal of the T line appeared. The detection signal intensity of the T line increased with increasing concentrations of Cr(3+). The low detection limit of developed fluorescence quenching ICS was 1.56 ng/mL. The fluorescence quenching ICS has a linear range of detection of Cr(3+) comprising between 6.25 ng/mL to 800 ng/mL. The recoveries of the fluorescence quenching ICS to detect Cr(3+) in tap water ranged from 94.7% to 101.7%. This result indicated that the developed sensor gave higher sensitivity and reliable reproducibility. It could provide a general detection method for small analyte in water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Automated quantification of myocardial perfusion SPECT using simplified normal limits.

PubMed

Slomka, Piotr J; Nishina, Hidetaka; Berman, Daniel S; Akincioglu, Cigdem; Abidov, Aiden; Friedman, John D; Hayes, Sean W; Germano, Guido

2005-01-01

To simplify development of normal limits for myocardial perfusion SPECT (MPS), we implemented a quantification scheme in which normal limits are derived without visual scoring of abnormal scans or optimization of regional thresholds. Normal limits were derived from same-day TI-201 rest/Tc-99m-sestamibi stress scans of male (n = 40) and female (n = 40) low-likelihood patients. Defect extent, total perfusion deficit (TPD), and regional perfusion extents were derived by comparison to normal limits in polar-map coordinates. MPS scans from 256 consecutive patients without known coronary artery disease, who underwent coronary angiography, were analyzed. The new method of quantification (TPD) was compared with our previously developed quantification system and visual scoring. The receiver operator characteristic area under the curve for detection of 50% or greater stenoses by TPD (0.88 +/- 0.02) was higher than by visual scoring (0.83 +/- 0.03) ( P = .039) or standard quantification (0.82 +/- 0.03) ( P = .004). For detection of 70% or greater stenoses, it was higher for TPD (0.89 +/- 0.02) than for standard quantification (0.85 +/- 0.02) ( P = .014). Sensitivity and specificity were 93% and 79%, respectively, for TPD; 81% and 85%, respectively, for visual scoring; and 80% and 73%, respectively, for standard quantification. The use of stress mode-specific normal limits did not improve performance. Simplified quantification achieves performance better than or equivalent to visual scoring or quantification based on per-segment visual optimization of abnormality thresholds.

CpG Oligonucleotide and Interleukin 2 stimulation enables higher cytogenetic abnormality detection rates than 12-o-tetradecanolyphorbol-13-acetate in Asian patients with B-cell chronic lymphocytic leukemia (B-CLL).

PubMed

Liaw, Fiona Pui San; Lau, Lai Ching; Lim, Alvin Soon Tiong; Lim, Tse Hui; Lee, Geok Yee; Tien, Sim Leng

2014-12-01

The present study was designed to compare abnormality detection rates using DSP30 + IL2 and 12-O-Tetradecanoylphorbol-13-acetate (TPA) in Asian patients with B-CLL. Hematological specimens from 47 patients (29 newly diagnosed, 18 relapsed) were established as 72 h-DSP30 + IL2 and TPA cultures. Standard methods were employed to identify clonal aberrations by conventional cytogenetics (CC). The B-CLL fluorescence in situ hybridization (FISH) panel comprised ATM, CEP12, D13S25, and TP53 probes. DSP30 + IL2 cultures had a higher chromosomal abnormality detection rate (67 %) compared to TPA (44 %, p < 0.001). The mean number of analyzable metaphases and abnormal metaphases per slide was also higher (p < 0.005, p < 0.001, respectively). Culture success rate, percentage of complex karyotype, and percentage of non-clonal abnormal cell were not significantly different (p > 0.05). Thirteen cases with abnormalities were found exclusively in DSP30 + IL2 cultures compared to one found solely in TPA cultures. DSP30 + IL2 cultures were comparable to the FISH panel in detecting 11q-, +12 and 17p- but not 13q-. It also has a predilection for 11q- bearing leukemic cells compared to TPA. FISH had a higher abnormality detection rate (84.1 %) compared to CC (66.0 %) with borderline significance (p = 0.051), albeit limited by its coverage. In conclusion, DSP30 + IL2 showed a higher abnormality detection rate. However, FISH is indispensable to circumvent low mitotic indices and detect subtle abnormalities.

Airborne Doppler radar detection of low altitude windshear

NASA Technical Reports Server (NTRS)

Bracalente, Emedio M.; Jones, William R.; Britt, Charles L.

1990-01-01

As part of an integrated windshear program, the Federal Aviation Administration, jointly with NASA, is sponsoring a research effort to develop airborne sensor technology for the detection of low altitude windshear during aircraft take-off and landing. One sensor being considered is microwave Doppler radar operating at X-band or above. Using a Microburst/Clutter/Radar simulation program, a preliminary feasibility study was conducted to assess the performance of Doppler radars for this application. Preliminary results from this study are presented. Analysis show, that using bin-to-bin Automatic Gain Control (AGC), clutter filtering, limited detection range, and suitable antenna tilt management, windshear from a wet microburst can be accurately detected 10 to 65 seconds (.75 to 5 km) in front of the aircraft. Although a performance improvement can be obtained at higher frequency, the baseline X-band system that was simulated detected the presence of a windshear hazard for the dry microburst. Although this study indicates the feasibility of using an airborne Doppler radar to detect low altitude microburst windshear, further detailed studies, including future flight experiments, will be required to completely characterize the capabilities and limitations.

Antibacterial activity of the lactoperoxidase system combined with edible Laminaria hot-water extract as a source of halide ions.

PubMed

Shin, Kouichirou; Nakano, Manabu; Yamauchi, Koji; Toida, Tomohiro; Iwatsuki, Keiji

2012-01-01

Hot-water extracts prepared from nine out of 12 samples of dried edible Laminaria reduced the viable numbers of Aggregatibacter actinomycetemcomitans, Staphylococcus aureus, and Esherichia coli below the detection limit after incubation for 5 min when combined with lactoperoxidase, glucose oxidase, and glucose. Some extracts showed higher bactericidal activity and a higher OI(-) concentration in the assay mixture after ultrafiltration.

Prevalence of depression and anxiety in patients with chronic digestive system diseases: A multicenter epidemiological study

PubMed Central

Zhang, An-Zhong; Wang, Qing-Cai; Huang, Kun-Ming; Huang, Jia-Guo; Zhou, Chang-Hong; Sun, Fu-Qiang; Wang, Su-Wen; Wu, Feng-Ting

2016-01-01

AIM To investigate the prevalence of depression and anxiety in patients with chronic digestive system diseases. METHODS A total of 1736 patients with chronic digestive system diseases were included in this cross-sectional study, including 871 outpatients and 865 in-patients. A self-designed General Information for Patients of the Department of Gastroenterology of General Hospitals questionnaire was used to collect each patient’s general information, which included demographic data (including age, sex, marital status, and education) and disease characteristics (including major diseases, disease duration, principal symptoms, chronic pain, sleep disorder, and limited daily activities). RESULTS The overall detection rate was 31.11% (540/1736) for depression symptoms alone, 27.02% (469/1736) for anxiety symptoms alone, 20.68% (359/1736) for both depression and anxiety symptoms, and 37.44% (650/1736) for either depression or anxiety symptoms. Subjects aged 70 years or above had the highest detection rate of depression (44.06%) and anxiety symptoms (33.33%). χ2 trend test showed: the higher the body mass index (BMI), the lower the detection rate of depression and anxiety symptoms (χ2trend = 13.697, P < 0.001; χ2trend = 9.082, P = 0.003); the more severe the limited daily activities, the higher the detection rate of depression and anxiety symptoms (χ2trend = 130.455, P < 0.001, χ2trend = 108.528, P < 0.001); and the poorer the sleep quality, the higher the detection rate of depression and anxiety symptoms (χ2trend = 85.759, P < 0.001; χ2trend = 51.969, P < 0.001). Patients with digestive system tumors had the highest detection rate of depression (57.55%) and anxiety (55.19%), followed by patients with liver cirrhosis (41.35% and 48.08%). Depression and anxiety symptoms were also high in subjects with comorbid hypertension and coronary heart disease. CONCLUSION Depression and anxiety occur in patients with tumors, liver cirrhosis, functional dyspepsia, and chronic viral hepatitis. Elderly, divorced/widowed, poor sleep quality, and lower BMI are associated with higher risk of depression and anxiety. PMID:27895432

Prevalence of depression and anxiety in patients with chronic digestive system diseases: A multicenter epidemiological study.

PubMed

Zhang, An-Zhong; Wang, Qing-Cai; Huang, Kun-Ming; Huang, Jia-Guo; Zhou, Chang-Hong; Sun, Fu-Qiang; Wang, Su-Wen; Wu, Feng-Ting

2016-11-14

To investigate the prevalence of depression and anxiety in patients with chronic digestive system diseases. A total of 1736 patients with chronic digestive system diseases were included in this cross-sectional study, including 871 outpatients and 865 in-patients. A self-designed General Information for Patients of the Department of Gastroenterology of General Hospitals questionnaire was used to collect each patient's general information, which included demographic data (including age, sex, marital status, and education) and disease characteristics (including major diseases, disease duration, principal symptoms, chronic pain, sleep disorder, and limited daily activities). The overall detection rate was 31.11% (540/1736) for depression symptoms alone, 27.02% (469/1736) for anxiety symptoms alone, 20.68% (359/1736) for both depression and anxiety symptoms, and 37.44% (650/1736) for either depression or anxiety symptoms. Subjects aged 70 years or above had the highest detection rate of depression (44.06%) and anxiety symptoms (33.33%). χ 2 trend test showed: the higher the body mass index (BMI), the lower the detection rate of depression and anxiety symptoms ( χ 2 trend = 13.697, P < 0.001; χ 2 trend = 9.082, P = 0.003); the more severe the limited daily activities, the higher the detection rate of depression and anxiety symptoms ( χ 2 trend = 130.455, P < 0.001, χ 2 trend = 108.528, P < 0.001); and the poorer the sleep quality, the higher the detection rate of depression and anxiety symptoms ( χ 2 trend = 85.759, P < 0.001; χ 2 trend = 51.969, P < 0.001). Patients with digestive system tumors had the highest detection rate of depression (57.55%) and anxiety (55.19%), followed by patients with liver cirrhosis (41.35% and 48.08%). Depression and anxiety symptoms were also high in subjects with comorbid hypertension and coronary heart disease. Depression and anxiety occur in patients with tumors, liver cirrhosis, functional dyspepsia, and chronic viral hepatitis. Elderly, divorced/widowed, poor sleep quality, and lower BMI are associated with higher risk of depression and anxiety.

The limit of detection in scintigraphic imaging with I-131 in patients with differentiated thyroid carcinoma

NASA Astrophysics Data System (ADS)

Hänscheid, H.; Lassmann, M.; Buck, A. K.; Reiners, C.; Verburg, F. A.

2014-05-01

Radioiodine scintigraphy influences staging and treatment in patients with differentiated thyroid carcinoma. The limit of detection for fractional uptake in an iodine avid focus in a scintigraphic image was determined from the number of lesion net counts and the count density of the tissue background. The count statistics were used to calculate the diagnostic activity required to elevate the signal from a lesion with a given uptake significantly above a homogeneous background with randomly distributed counts per area. The dependences of the minimal uptake and the minimal size of lesions visible in a scan on several parameters of influence were determined by linking the typical biokinetics observed in iodine avid tissue to the lesion mass and to the absorbed dose received in a radioiodine therapy. The detection limits for fractional uptake in a neck lesion of a typical patient are about 0.001% after therapy with 7000 MBq, 0.01% for activities typically administered in diagnostic assessments (74-185 MBq), and 0.1% after the administration of 10 MBq I-131. Lesions at the limit of detection in a diagnostic scan with biokinetics eligible for radioiodine therapy are small with diameters of a few millimeters. Increasing the diagnostic activity by a factor of 4 reduces the diameter of visible lesions by 25% or about 1 mm. Several other determinants have a comparable or higher influence on the limit of detection than the administered activity; most important are the biokinetics in both blood pool and target tissue and the time of measurement. A generally valid recommendation for the timing of the scan is impossible as the time of the highest probability to detect iodine avid tissue depends on the administered activity as well as on the biokinetics in the lesion and background in the individual patient.

The Need and Potential of Biosensors to Detect Dioxins and Dioxin-Like Polychlorinated Biphenyls along the Milk, Eggs and Meat Food Chain

PubMed Central

Chobtang, Jeerasak; de Boer, Imke J. M.; Hoogenboom, Ron L. A. P.; Haasnoot, Willem; Kijlstra, Aize; Meerburg, Bastiaan G.

2011-01-01

Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) are hazardous toxic, ubiquitous and persistent chemical compounds, which can enter the food chain and accumulate up to higher trophic levels. Their determination requires sophisticated methods, expensive facilities and instruments, well-trained personnel and expensive chemical reagents. Ideally, real-time monitoring using rapid detection methods should be applied to detect possible contamination along the food chain in order to prevent human exposure. Sensor technology may be promising in this respect. This review gives the state of the art for detecting possible contamination with dioxins and DL-PCBs along the food chain of animal-source foods. The main detection methods applied (i.e., high resolution gas-chromatography combined with high resolution mass-spectrometry (HRGC/HRMS) and the chemical activated luciferase gene expression method (CALUX bioassay)), each have their limitations. Biosensors for detecting dioxins and related compounds, although still under development, show potential to overcome these limitations. Immunosensors and biomimetic-based biosensors potentially offer increased selectivity and sensitivity for dioxin and DL-PCB detection, while whole cell-based biosensors present interpretable biological results. The main shortcoming of current biosensors, however, is their detection level: this may be insufficient as limits for dioxins and DL-PCBs for food and feedstuffs are in pg per gram level. In addition, these contaminants are normally present in fat, a difficult matrix for biosensor detection. Therefore, simple and efficient extraction and clean-up procedures are required which may enable biosensors to detect dioxins and DL-PCBs contamination along the food chain. PMID:22247688

The need and potential of biosensors to detect dioxins and dioxin-like polychlorinated biphenyls along the milk, eggs and meat food chain.

PubMed

Chobtang, Jeerasak; de Boer, Imke J M; Hoogenboom, Ron L A P; Haasnoot, Willem; Kijlstra, Aize; Meerburg, Bastiaan G

2011-01-01

Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) are hazardous toxic, ubiquitous and persistent chemical compounds, which can enter the food chain and accumulate up to higher trophic levels. Their determination requires sophisticated methods, expensive facilities and instruments, well-trained personnel and expensive chemical reagents. Ideally, real-time monitoring using rapid detection methods should be applied to detect possible contamination along the food chain in order to prevent human exposure. Sensor technology may be promising in this respect. This review gives the state of the art for detecting possible contamination with dioxins and DL-PCBs along the food chain of animal-source foods. The main detection methods applied (i.e., high resolution gas-chromatography combined with high resolution mass-spectrometry (HRGC/HRMS) and the chemical activated luciferase gene expression method (CALUX bioassay)), each have their limitations. Biosensors for detecting dioxins and related compounds, although still under development, show potential to overcome these limitations. Immunosensors and biomimetic-based biosensors potentially offer increased selectivity and sensitivity for dioxin and DL-PCB detection, while whole cell-based biosensors present interpretable biological results. The main shortcoming of current biosensors, however, is their detection level: this may be insufficient as limits for dioxins and DL-PCBs for food and feedstuffs are in pg per gram level. In addition, these contaminants are normally present in fat, a difficult matrix for biosensor detection. Therefore, simple and efficient extraction and clean-up procedures are required which may enable biosensors to detect dioxins and DL-PCBs contamination along the food chain.

Cumulative detection probabilities and range accuracy of a pulsed Geiger-mode avalanche photodiode laser ranging system

NASA Astrophysics Data System (ADS)

Luo, Hanjun; Ouyang, Zhengbiao; Liu, Qiang; Chen, Zhiliang; Lu, Hualan

2017-10-01

Cumulative pulses detection with appropriate cumulative pulses number and threshold has the ability to improve the detection performance of the pulsed laser ranging system with GM-APD. In this paper, based on Poisson statistics and multi-pulses cumulative process, the cumulative detection probabilities and their influence factors are investigated. With the normalized probability distribution of each time bin, the theoretical model of the range accuracy and precision is established, and the factors limiting the range accuracy and precision are discussed. The results show that the cumulative pulses detection can produce higher target detection probability and lower false alarm probability. However, for a heavy noise level and extremely weak echo intensity, the false alarm suppression performance of the cumulative pulses detection deteriorates quickly. The range accuracy and precision is another important parameter evaluating the detection performance, the echo intensity and pulse width are main influence factors on the range accuracy and precision, and higher range accuracy and precision is acquired with stronger echo intensity and narrower echo pulse width, for 5-ns echo pulse width, when the echo intensity is larger than 10, the range accuracy and precision lower than 7.5 cm can be achieved.

Multi-wavelength Spatial LED illumination based detector for in vitro detection of Botulinum Neurotoxin A Activity

PubMed Central

Sun, Steven; Francis, Jesse; Sapsford, Kim E.; Kostov, Yordan; Rasooly, Avraham

2010-01-01

A portable and rapid detection system for the activity analysis of Botulinum Neurotoxins (BoNT) is needed for food safety and bio-security applications. To improve BoNT activity detection, a previously designed portable charge-coupled device (CCD) based detector was modified and equipped with a higher intensity more versatile multi-wavelength spatial light-emitting diode (LED) illumination, a faster CCD detector and the capability to simultaneously detect 30 samples. A FITC/DABCYL Förster Resonance Energy Transfer (FRET)-labeled peptide substrate (SNAP-25), with BoNT-A target cleavage site sequence was used to measure BoNT-A light chain (LcA) activity through the FITC fluorescence increase that occurs upon peptide substrate cleavage. For fluorescence excitation, a multi-wavelength spatial LED illuminator was used and compared to our previous electroluminescent (EL) strips. The LED illuminator was equipped with blue, green, red and white LEDs, covering a spectrum of 450-680 nm (red 610-650 nm, green 492-550 nm, blue 450-495 nm, and white LED 440-680 nm). In terms of light intensity, the blue LED was found to be ~80 fold higher than the previously used blue EL strips. When measuring the activity of LcA the CCD detector limit of detection (LOD) was found to be 0.08 nM LcA for both the blue LED (2 s exposure) and the blue EL (which require ≥60 s exposure) while the limits of quantitation (LOQ) is about 1 nM. The LOD for white LED was higher at 1.4 nM while the white EL was not used for the assay due to a high variable background. Unlike the weaker intensity EL illumination the high intensity LED illumination enabled shorter exposure times and allowed multi-wavelength illumination without the need to physically change the excitation strip, thus making spectrum excitation of multiple fluorophores possible increasing the versatility of the detector platform for a variety of optical detection assays. PMID:20498728

Serum Cystatin C– Versus Creatinine-Based Definitions of Acute Kidney Injury Following Cardiac Surgery: A Prospective Cohort Study

PubMed Central

Spahillari, Aferdita; Parikh, Chirag R.; Sint, Kyaw; Koyner, Jay L.; Patel, Uptal D.; Edelstein, Charles L.; Passik, Cary S.; Thiessen-Philbrook, Heather; Swaminathan, Madhav; Shlipak, Michael G.

2012-01-01

Background The primary aim of this study was to compare the sensitivity and rapidity of AKI detection by cystatin C relative to creatinine following cardiac surgery. Study Design Prospective cohort study Settings and Participants 1,150 high-risk, adult cardiac surgery patients in the TRIBE-AKI (Translational Research Investigating Biomarker Endpoints for Acute Kidney Injury) Consortium. Predictor Changes in serum creatinine and cystatin C Outcome Post-surgical incidence of AKI Measurements Serum creatinine and cystatin C were measured at the preoperative visit and daily on postoperative days 1–5. To allow comparisons between changes in creatinine and cystatin C, AKI endpoints were defined by the relative increases in each marker from baseline (25, 50 and 100%) and the incidence of AKI was compared based upon each marker. Secondary aims were to compare clinical outcomes among patients defined as having AKI by cystatin C and/or creatinine. Results Overall, serum creatinine detected more cases of AKI than cystatin C: 35% developed a ≥25% increase in serum creatinine, whereas only 23% had ≥25% increase in cystatin C (p < 0.001). Creatinine also had higher proportions meeting the 50% (14% and 8%, p<0.001) and 100% (4% and 2%, p=0.005) thresholds for AKI diagnosis. Clinical outcomes were generally not statistically different for AKI cases detected by creatinine or cystatin C. However, for each AKI threshold, patients with AKI confirmed by both markers had significantly higher risk of the combined mortality/dialysis outcome compared with patients with AKI detected by creatinine alone (p=0.002). Limitations There were few adverse clinical outcomes, limiting our ability to detect differences in outcomes between subgroups of patients based upon their definitions of AKI. Conclusion In this large multicenter study, we found that cystatin C was less sensitive for AKI detection compared with creatinine. However, confirmation by cystatin C appeared to identify a subset of AKI patients with substantially higher risk of adverse outcomes. PMID:22809763

Temporal modulation transfer functions in cochlear implantees using a method that limits overall loudness cues

PubMed Central

Fraser, Matthew; McKay, Colette M.

2012-01-01

Temporal modulation transfer functions (TMTFs) were measured for six users of cochlear implants, using different carrier rates and levels. Unlike most previous studies investigating modulation detection, the experimental design limited potential effects of overall loudness cues. Psychometric functions (percent correct discrimination of modulated from unmodulated stimuli versus modulation depth) were obtained. For each modulation depth, each modulated stimulus was loudness balanced to the unmodulated reference stimulus, and level jitter was applied in the discrimination task. The loudness-balance data showed that the modulated stimuli were louder than the unmodulated reference stimuli with the same average current, thus confirming the need to limit loudness cues when measuring modulation detection. TMTFs measured in this way had a low-pass characteristic, with a cut-off frequency (at comfortably loud levels) similar to that for normal-hearing listeners. A reduction in level caused degradation in modulation detection efficiency and a lower-cut-off frequency (i.e. poorer temporal resolution). An increase in carrier rate also led to a degradation in modulation detection efficiency, but only at lower levels or higher modulation frequencies. When detection thresholds were expressed as a proportion of dynamic range, there was no effect of carrier rate for the lowest modulation frequency (50 Hz) at either level. PMID:22146425

Rapid detection of total and viable Legionella pneumophila in tap water by immunomagnetic separation, double fluorescent staining and flow cytometry.

PubMed

Keserue, Hans-Anton; Baumgartner, Andreas; Felleisen, Richard; Egli, Thomas

2012-11-01

We developed a rapid detection method for Legionella pneumophila (Lp) by filtration, immunomagnetic separation, double fluorescent staining, and flow cytometry (IMS-FCM method). The method requires 120 min and can discriminate 'viable' and 'membrane-damaged' cells. The recovery is over 85% of spiked Lp SG 1 cells in 1 l of tap water and detection limits are around 50 and 15 cells per litre for total and viable Lp, respectively. The method was compared using water samples from house installations in a blind study with three environmental laboratories performing the ISO 11731 plating method. In 53% of the water samples from different taps and showers significantly higher concentrations of Lp were detected by flow cytometry. No correlation to the plate culture method was found. Since also 'viable but not culturable' (VNBC) cells are detected by our method, this result was expected. The IMS-FCM method is limited by the specificity of the used antibodies; in the presented case they target Lp serogroups 1-12. This and the fact that no Lp-containing amoebae are detected may explain why in 21% of all samples higher counts were observed using the plate culture method. Though the IMS-FCM method is not yet fit to completely displace the established plating method (ISO 11731) for routine Lp monitoring, it has major advantages to plating and can quickly provide important insights into the ecology of this pathogen in water distribution systems. © 2012 The Authors. Microbial Biotechnology © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Occurrence and concentrations of pharmaceutical compounds in groundwater used for public drinking-water supply in California.

PubMed

Fram, Miranda S; Belitz, Kenneth

2011-08-15

Pharmaceutical compounds were detected at low concentrations in 2.3% of 1231 samples of groundwater (median depth to top of screened interval in wells=61 m) used for public drinking-water supply in California. Samples were collected statewide for the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program. Of 14 pharmaceutical compounds analyzed, 7 were detected at concentrations greater than or equal to method detection limits: acetaminophen (used as an analgesic, detection frequency 0.32%, maximum concentration 1.89 μg/L), caffeine (stimulant, 0.24%, 0.29 μg/L), carbamazepine (mood stabilizer, 1.5%, 0.42 μg/L), codeine (opioid analgesic, 0.16%, 0.214 μg/L), p-xanthine (caffeine metabolite, 0.08%, 0.12 μg/L), sulfamethoxazole (antibiotic, 0.41%, 0.17 μg/L), and trimethoprim (antibiotic, 0.08%, 0.018 μg/L). Detection frequencies of pesticides (33%), volatile organic compounds not including trihalomethanes (23%), and trihalomethanes (28%) in the same 1231 samples were significantly higher. Median detected concentration of pharmaceutical compounds was similar to those of volatile organic compounds, and higher than that of pesticides. Pharmaceutical compounds were detected in 3.3% of the 855 samples containing modern groundwater (tritium activity>0.2 TU). Pharmaceutical detections were significantly positively correlated with detections of urban-use herbicides and insecticides, detections of volatile organic compounds, and percentage of urban land use around wells. Groundwater from the Los Angeles metropolitan area had higher detection frequencies of pharmaceuticals and other anthropogenic compounds than groundwater from other areas of the state with similar proportions of urban land use. The higher detection frequencies may reflect that groundwater flow systems in Los Angeles area basins are dominated by engineered recharge and intensive groundwater pumping. Published by Elsevier B.V.

Surface Plasmon Resonance Based Sensitive Immunosensor for Benzaldehyde Detection

NASA Astrophysics Data System (ADS)

Onodera, Takeshi; Shimizu, Takuzo; Miura, Norio; Matsumoto, Kiyoshi; Toko, Kiyoshi

Fragrant compounds used to add flavor to beverages remain in the manufacturing line after the beverage manufacturing process. Line cleanliness before the next manufacturing cycle is difficult to estimate by sensory analysis, making excessive washing necessary. A new measurement system to determine line cleanliness is desired. In this study, we attempted to detect benzaldehyde (Bz) using an anti-Bz monoclonal antibody (Bz-Ab) and a surface plasmon resonance (SPR) sensor. We fabricated two types of sensor chips using self-assembled monolayers (SAMs) and investigated which sensor surface exhibited higher sensitivity. In addition, anti-Bz antibody conjugated with horseradish peroxidase (HRP-Bz-Ab) was used to enhance the SPR signal. A detection limit of ca. 9ng/mL (ppb) was achieved using an immobilized 4-carboxybenzaldehyde sensor surface using SAMs containing ethylene glycol. When the HRP-Bz-Ab concentration was reduced to 30ng/mL, a detection limit of ca. 4ng/mL (ppb) was achieved for Bz.

Rapid detection of microorganisms based on active and passive modes of QCM.

PubMed

Farka, Zdeněk; Kovář, David; Skládal, Petr

2014-12-23

Label-free immunosensors are well suited for detection of microorganisms because of their fast response and reasonable sensitivity comparable to infection doses of common pathogens. Active (lever oscillator and frequency counter) and passive (impedance analyzer) modes of quartz crystal microbalance (QCM) were used and compared for rapid detection of three strains of E. coli. Different approaches for antibody immobilization were compared, the immobilization of reduced antibody using Sulfo-SMCC was most effective achieving the limit of detection (LOD) 8 × 104 CFU·mL-1 in 10 min. For the passive mode, software evaluating impedance characteristics in real-time was developed and used. Almost the same results were achieved using both active and passive modes confirming that the sensor properties are not limited by the frequency evaluation method but mainly by affinity of the antibody. Furthermore, reference measurements were done using surface plasmon resonance. Effect of condition of cells on signal was observed showing that cells ruptured by ultrasonication provided slightly higher signal changes than intact microbes.

Rapid Detection of Microorganisms Based on Active and Passive Modes of QCM

PubMed Central

Farka, Zdeněk; Kovář, David; Skládal, Petr

2015-01-01

Label-free immunosensors are well suited for detection of microorganisms because of their fast response and reasonable sensitivity comparable to infection doses of common pathogens. Active (lever oscillator and frequency counter) and passive (impedance analyzer) modes of quartz crystal microbalance (QCM) were used and compared for rapid detection of three strains of E. coli. Different approaches for antibody immobilization were compared, the immobilization of reduced antibody using Sulfo‐SMCC was most effective achieving the limit of detection (LOD) 8 × 104 CFU·mL−1 in 10 min. For the passive mode, software evaluating impedance characteristics in real-time was developed and used. Almost the same results were achieved using both active and passive modes confirming that the sensor properties are not limited by the frequency evaluation method but mainly by affinity of the antibody. Furthermore, reference measurements were done using surface plasmon resonance. Effect of condition of cells on signal was observed showing that cells ruptured by ultrasonication provided slightly higher signal changes than intact microbes. PMID:25545267

Gas chromatography with flame photometric detection of 31 organophosphorus pesticide residues in Alpinia oxyphylla dried fruits.

PubMed

Zhao, Xiangsheng; Kong, Weijun; Wei, Jianhe; Yang, Meihua

2014-11-01

A simple, rapid and effective gas chromatography-flame photometric detection method was established for simultaneous multi-component determination of 31 organophosphorus pesticides (OPPs) residues in Alpinia oxyphylla, which is widely consumed as a traditional medicine and food in China. Sample preparation was completed in a single step without any clean-up procedure. All pesticides expressed good linear relationships between 0.004 and 1.0 μg/mL with correlation coefficients higher than 0.9973. The method gave satisfactory recoveries for most pesticides. The limits of detection varied from 1 to 10 ng/mL, and the limits of quantification (LOQs) were between 4 and 30 ng/mL. The proposed method was successfully applied to 55 commercial samples purchased from five different areas. Five pesticide residues were detected in four (7.27%) samples. The positive samples were confirmed by gas chromatography with tandem mass spectrometry (GC-MS/MS). Copyright © 2014 Elsevier Ltd. All rights reserved.

Experimental study on anomalous neutron production in deuterium/solid system

NASA Astrophysics Data System (ADS)

He, Jianyu; Zhu, Rongbao; Wang, Xiaozhong; Lu, Feng; Luo, Longjun; Liu, Hengjun; Jiang, Jincai; Tian, Baosheng; Chen, Guoan; Yuan, Yuan; Dong, Baiting; Yang, Liucheng; Qiao, Shengzhong; Yi, Guoan; Guo, Hua; Ding, Dazhao; Menlove, H. O.

1991-05-01

A series of experiments on both D2O electrolysis and thermal cycle of deuterium absorbed Ti Turnings has been designed to examine the anomalous phenomena in Deuterium/Solid System. A neutron detector containing 16 BF3 tubes with a detection limit of 0.38 n/s for two hour counting was used for electrolysis experiments. No neutron counting rate statistically higher than detection limit was observed from Fleischmann & Pons type experiments. An HLNCC neutron detector equipped with 18 3He tubes and a JSR-11 shift register unit with a detection limit of 0.20 n/s for a two hour run was employed to study the neutron signals in D2 gas experiments. Different material pretreatments were selected to review the changes in frequency and size of the neutron burst production. Experiment sequence was deliberately designed to distinguish the neutron burst from fake signals, e.g. electronic noise pickup, the cosmic rays and other sources of environmental background. Ten batches of dry fusion samples were tested, among them, seven batches with neutron burst signals occurred roughly at the temperature from -100 degree centigrade to near room temperature. In the first four runs of a typical sample batch, seven neutron bursts were observed with neutron numbers from 15 to 482, which are 3 and 75 times, respectively, higher than the uncertainty of background. However, no bursts happened for H2 dummy samples running in-between and afterwards and for sample batch after certain runs.

Impedimetric Zika and Dengue Biosensor based on Functionalized Graphene Oxide Wrapped Silica Particles

NASA Astrophysics Data System (ADS)

Jin, Seon-Ah; Marinero, Ernesto E.; Stanciu, Lia A. Stanciu; Poudyal, Shishir; Kuhn, Richard J.

A composite of 3-Aminopropyltriethoxysilane (APTES) functionalized graphene oxide (APTES-GO) wrapped on SiO2 particles (SiO2@APTES-GO) was prepared via self-assembly. Transmission electron microscopy (TEM) and ATR-Fourier Transform Infrared spectroscopy (ATR-FTIR) confirmed wrapping of the SiO2 particles by the APTES-GO sheets. An impedimetric biosensor was constructed and used to sensitively detect Zika and dengue DNA and RNA via primer hybridization using different oligonucleotide sequences. The results demonstrate that the SiO2@APTES-GO electrode materials provide enhanced RNA detection sensitivity with selectivity and detection limit (1 femto-Molar), compared to both APTES-GO and APTES-SiO2. The three-dimensional structure, higher contact area, electrical properties and the ability for rapid hybridization offered by the SiO2@APTES-GO resulted in a successful design of a Zika and dengue biosensor with the lowest detection limit reported to date. We are in the process of developing a platform for multiple viral detection for point-of-care diagnostics for arthropode borne viral infectious diseases.

Long-term implications of observing an expanding cosmological civilization

NASA Astrophysics Data System (ADS)

Olson, S. Jay

2018-01-01

Suppose that advanced civilizations, separated by a cosmological distance and time, wish to maximize their access to cosmic resources by rapidly expanding into the universe. How does the presence of one limit the expansionistic ambitions of another, and what sort of boundary forms between their expanding domains? We describe a general scenario for any expansion speed, separation distance and time. We then specialize to a question of particular interest: What are the future prospects for a young and ambitious civilization if they can observe the presence of another at a cosmological distance? We treat cases involving the observation of one or two expanding domains. In the single-observation case, we find that almost any plausible detection will limit one's future cosmic expansion to some extent. Also, practical technological limits to expansion speed (well below the speed of light) play an interesting role. If a domain is visible at the time one embarks on cosmic expansion, higher practical limits to expansion speed are beneficial only up to a certain point. Beyond this point, a higher speed limit means that gains in the ability to expand are more than offset by the first-mover advantage of the observed domain. In the case of two visible domains, it is possible to be `trapped' by them if the practical speed limit is high enough and their angular separation in the sky is large enough, i.e. one's expansion in any direction will terminate at a boundary with the two visible civilizations. Detection at an extreme cosmological distance has surprisingly little mitigating effect on our conclusions.

Occurrence of perchlorate in drinking water and seawater in South Korea.

PubMed

Her, Namguk; Jeong, Hyunchan; Kim, Jongsung; Yoon, Yeomin

2011-08-01

Concentrations of perchlorate were determined by both liquid-chromatography-mass spectrometry (LC-MS) and ion chromatography tandem mass spectrometry (IC-MS/MS) in 520 tap-water, 48 bottled-water, and 9 seawater samples obtained or purchased from >100 different locations in South Korea. The method detection limits were 0.013 μg/L for LC-MS and 0.005 μg/L for IC-MS/MS, and the limits of quantification (LOQs) were 0.10 μg/L for LC-MS and 0.032 μg/L for IC-MS/MS. Perchlorate was detected in most (80%) of the tap-water samples, with concentrations higher than the LOQ; the concentrations ranged from <1.0 to 6.1 μg/L (mean 0.56). Perchlorate was detected by IC-MS/MS in many (n = 23) of the bottled-water samples, with concentrations higher then the LOQ, ranging from 0.04 to 0.29 μg/L (mean 0.07 ± 0.01). The concentrations of perchlorate in all seawater samples collected from the various locations were higher than the LOQ, with a mean concentration of 1.15 ± 0.01 μg/L (maximum 6.11 and minimum 0.11). This study provides further evidence that drinking-water sources have been contaminated by perchlorate. To the best of our knowledge, this is the first comprehensive study on perchlorate assessment in drinking water and seawater in South Korea.

Detection and identification of extra virgin olive oil adulteration by GC-MS combined with chemometrics.

PubMed

Yang, Yang; Ferro, Miguel Duarte; Cavaco, Isabel; Liang, Yizeng

2013-04-17

In this study, an analytical method for the detection and identification of extra virgin olive oil adulteration with four types of oils (corn, peanut, rapeseed, and sunflower oils) was proposed. The variables under evaluation included 22 fatty acids and 6 other significant parameters (the ratio of linoleic/linolenic acid, oleic/linoleic acid, total saturated fatty acids (SFAs), polyunsaturated fatty acids (PUFAs), monounsaturated fatty acids (MUFAs), MUFAs/PUFAs). Univariate analyses followed by multivariate analyses were applied to the adulteration investigation. As a result, the univariate analyses demonstrated that higher contents of eicosanoic acid, docosanoic acid, tetracosanoic acid, and SFAs were the peculiarities of peanut adulteration and higher levels of linolenic acid, 11-eicosenoic acid, erucic acid, and nervonic acid the characteristics of rapeseed adulteration. Then, PLS-LDA made the detection of adulteration effective with a 1% detection limit and 90% prediction ability; a Monte Carlo tree identified the type of adulteration with 85% prediction ability.

Lectin functionalized ZnO nanoarrays as a 3D nano-biointerface for bacterial detection.

PubMed

Zheng, Laibao; Wan, Yi; Qi, Peng; Sun, Yan; Zhang, Dun; Yu, Liangmin

2017-05-15

The detection of pathogenic bacteria is essential in various fields, such as food safety, water environmental analysis, or clinical diagnosis. Although rapid and selective techniques have been achieved based on the fast and specific binding of recognitions elements and target, the sensitive detection of bacterial pathogens was limited by their low targets-binding efficiency. The three-dimensional (3D) nano-biointerface, compared with the two-dimensional (2D) flat substrate, has a much higher binding capacity, which can offer more reactive sites to bind with bacterial targets, resulting in a great improvement of detection sensitivity. Herein, a lectin functionalized ZnO nanorod (ZnO-NR) array has been fabricated and employed as a 3D nano-biointerface for Escherichia coli (E. coli) capture and detection by multivalent binding of concanavalin A (ConA) with polysaccharides on the cellular surface of E. coli. The 3D lectin functionalized ZnO-NR array-based assay shows reasonable detection limit and efficiently expanded linear range (1.0×10 3 to 1.0×10 7 cfumL -1 ) for pathogen detection. The platform has a potential for further applications and provides an excellent sensitivity approach for detection of pathogenic bacteria. Copyright © 2017 Elsevier B.V. All rights reserved.

Detection of alpha-fetoprotein in magnetic immunoassay of thin channels using biofunctional nanoparticles

NASA Astrophysics Data System (ADS)

Tsai, H. Y.; Gao, B. Z.; Yang, S. F.; Li, C. S.; Fuh, C. Bor

2014-01-01

This paper presents the use of fluorescent biofunctional nanoparticles (10-30 nm) to detect alpha-fetoprotein (AFP) in a thin-channel magnetic immunoassay. We used an AFP model biomarker and s-shaped deposition zones to test the proposed detection method. The results show that the detection using fluorescent biofunctional nanoparticle has a higher throughput than that of functional microparticle used in previous experiments on affinity reactions. The proposed method takes about 3 min (versus 150 min of previous method) to detect 100 samples. The proposed method is useful for screening biomarkers in clinical applications, and can reduce the run time for sandwich immunoassays to less than 20 min. The detection limits (0.06 pg/ml) and linear ranges (0.068 pg/ml-0.68 ng/ml) of AFP using fluorescent biofunctional nanoparticles are the same as those of using functional microparticles within experimental errors. This detection limit is substantially lower and the linear range is considerably wider than those of enzyme-linked immunosorbent assay (ELISA) and other methods in sandwich immunoassay methods. The differences between this method and an ELISA in AFP measurements of serum samples were less than 12 %. The proposed method provides simple, fast, and sensitive detection with a high throughput for biomarkers.

Determination of bisphenol A in human serum by high-performance liquid chromatography with multi-electrode electrochemical detection.

PubMed

Inoue, K; Kato, K; Yoshimura, Y; Makino, T; Nakazawa, H

2000-11-10

A simple and sensitive method using high-performance liquid chromatography with multi-electrode electrochemical detection (HPLC-ED) including a coulometric array of four electrochemical sensors has been developed for the determination of bisphenol A in water and human serum. For good separation and detection of bisphenol A, a CAPCELL PAK UG 120 C18 reversed-phase column and a mobile phase consisting of 0.3% phosphoric acid-acetonitrile (60:40) were used. The detection limit obtained by the HPLC-ED method was 0.01 ng/ml (0.5 pg), which was more than 3000-times higher than the detection limit obtained by the ultraviolet (UV) method, and more than 200-times higher than the detection limit obtained by the fluorescence (FL) method. Bisphenol A in water and serum samples was pretreated by solid-phase extraction (SPE) after removing possible contamination derived from a plastic SPE cartridges and water used for the pretreatment. A trace amount (ND approximately 0.013 ng/ml) of bisphenol A was detected from the parts of cartridges (filtration column, sorbent bed and frits) by extraction with methanol, and it was completely removed by washing with at least 15 ml of methanol in the operation process. The concentrations of bisphenol A in tap water and Milli-Q-purified water were found to be 0.01 and 0.02 ng/ml, respectively. For that reason, bisphenol A-free water was made to trap bisphenol A in water using an Empore disk. In every pretreatment, SPE methods using bisphenol A-free water and washing with 15 ml of methanol were done in water and serum samples. The yields obtained from the recovery tests using water to which 0.5 or 0.05 ng/ml of bisphenol A was added were 83.8 to 98.2%, and the RSDs were 3.4 to 6.1%, respectively. The yields obtained from the recovery tests by OASIS HLB using serum to which 1.0 ng/ml or 0.1 ng/ml of bisphenol A was added were 79.0% and 87.3%, and the RSDs were 5.1% and 13.5%, respectively. The limits of quantification in water and serum sample were 0.01 ng/ml and 0.05 ng/ml, respectively. The method was applied to the determination of bisphenol A in healthy human serum sample, and the obtained detection was 0.32 ng/ml. From these results, the HPLC-ED method should be the most useful in the determination of bisphenol A at low concentration levels in water and biological samples.

Limits to Sensitivity in Laser Enhanced Ionization.

ERIC Educational Resources Information Center

Travis, J. C.

1982-01-01

Laser enhanced ionization (LEI) occurs when a tunable dye laser is used to excite a specific atomic population in a flame. Explores the origin of LEI's high sensitivity and identifies possible avenues to higher sensitivity by describing instrument used and experimental procedures and discussing ion formation/detection. (Author/JN)

Digital Holographic Microscopy, a Method for Detection of Microorganisms in Plume Samples from Enceladus and Other Icy Worlds

PubMed Central

Bedrossian, Manuel; Lindensmith, Chris

2017-01-01

Abstract Detection of extant microbial life on Earth and elsewhere in the Solar System requires the ability to identify and enumerate micrometer-scale, essentially featureless cells. On Earth, bacteria are usually enumerated by culture plating or epifluorescence microscopy. Culture plates require long incubation times and can only count culturable strains, and epifluorescence microscopy requires extensive staining and concentration of the sample and instrumentation that is not readily miniaturized for space. Digital holographic microscopy (DHM) represents an alternative technique with no moving parts and higher throughput than traditional microscopy, making it potentially useful in space for detection of extant microorganisms provided that sufficient numbers of cells can be collected. Because sample collection is expected to be the limiting factor for space missions, especially to outer planets, it is important to quantify the limits of detection of any proposed technique for extant life detection. Here we use both laboratory and field samples to measure the limits of detection of an off-axis digital holographic microscope (DHM). A statistical model is used to estimate any instrument's probability of detection at various bacterial concentrations based on the optical performance characteristics of the instrument, as well as estimate the confidence interval of detection. This statistical model agrees well with the limit of detection of 103 cells/mL that was found experimentally with laboratory samples. In environmental samples, active cells were immediately evident at concentrations of 104 cells/mL. Published estimates of cell densities for Enceladus plumes yield up to 104 cells/mL, which are well within the off-axis DHM's limits of detection to confidence intervals greater than or equal to 95%, assuming sufficient sample volumes can be collected. The quantitative phase imaging provided by DHM allowed minerals to be distinguished from cells. Off-axis DHM's ability for rapid low-level bacterial detection and counting shows its viability as a technique for detection of extant microbial life provided that the cells can be captured intact and delivered to the sample chamber in a sufficient volume of liquid for imaging. Key Words: In situ life detection—Extant microorganisms—Holographic microscopy—Ocean Worlds—Enceladus—Imaging. Astrobiology 17, 913–925. PMID:28708412

Solid phase microextraction applied to the analysis of organophosphorus insecticides in fruits.

PubMed

Fytianos, K; Raikos, N; Theodoridis, G; Velinova, Z; Tsoukali, H

2006-12-01

Trace amounts of organophosphorus pesticides (OPs) were determined in various fruits by headspace solid phase microextraction (HS-SPME) and gas chromatography-nitrogen phosphorous detection (GC-NPD). Sampling from the headspace enhanced method selectivity, whereas at the same time improved fiber life time and method sensitivity. Diazinon, parathion, methyl parathion, malathion and fenithrothion were determined in various fruits: more than 150 samples of 21 types of fruits were studied. SPME-GC-NPD provided a useful and very efficient analytical tool: method linearity ranged from 1.2 to 700 ng/ml. Limits of detection (LODs) and quantitation (LOQs) ranged from 0.03 to 3 ng/ml and 0.12 to 10 ng/ml respectively, values well below the residue limits set by the EU. Less than 2% of the samples were found positive containing amounts higher than the EU limits. The effect of fruit peeling and washing was also investigated.

Multi-Frequency Signal Detection Based on Frequency Exchange and Re-Scaling Stochastic Resonance and Its Application to Weak Fault Diagnosis.

PubMed

Liu, Jinjun; Leng, Yonggang; Lai, Zhihui; Fan, Shengbo

2018-04-25

Mechanical fault diagnosis usually requires not only identification of the fault characteristic frequency, but also detection of its second and/or higher harmonics. However, it is difficult to detect a multi-frequency fault signal through the existing Stochastic Resonance (SR) methods, because the characteristic frequency of the fault signal as well as its second and higher harmonics frequencies tend to be large parameters. To solve the problem, this paper proposes a multi-frequency signal detection method based on Frequency Exchange and Re-scaling Stochastic Resonance (FERSR). In the method, frequency exchange is implemented using filtering technique and Single SideBand (SSB) modulation. This new method can overcome the limitation of "sampling ratio" which is the ratio of the sampling frequency to the frequency of target signal. It also ensures that the multi-frequency target signals can be processed to meet the small-parameter conditions. Simulation results demonstrate that the method shows good performance for detecting a multi-frequency signal with low sampling ratio. Two practical cases are employed to further validate the effectiveness and applicability of this method.

Performance of a Borehole XRF Spectrometer for Planetary Exploration

NASA Technical Reports Server (NTRS)

Kelliher, Warren C.; Carlberg, Ingrid A.; Elam, W. T.; WIllard-Schmoe, Ella

2007-01-01

We have designed and constructed a borehole XRF Spectrometer (XRFS) as part of the Mars Subsurface Access program. It will be used to determine the composition of the Mars regolith at various depths by insertion into a pre-drilled borehole. The primary performance metrics for the instrument are the lower limits of detection over a wide range of the periodic table. Power consumption during data collection was also measured. The prototype instrument is complete and preliminary testing has been performed. Terrestrial soil Standard Reference Materials were used as the test samples. Detection limits were about 10 weight parts-per-million for most elements, with light elements being higher, up to 1.4 weight percent for magnesium. Power consumption (excluding ground support components) was 12 watts.

Peptide Functionalized Gold Nanorods for the Sensitive Detection of a Cardiac Biomarker Using Plasmonic Paper Devices (Postprint)

DTIC Science & Technology

2015-11-10

currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YY) 2. REPORT TYPE 3 . DATES COVERED...refractive index difference on the order of 3 × 10−4 refractive index units (RIU)), probe the conformational changes of individual biomacromolecules...natural antibodies and short peptides, as BREs. We demonstrate that pep - tides provide a significantly higher sensitivity and lower limit of detection

High-Level Data Races

NASA Technical Reports Server (NTRS)

Artho, Cyrille; Havelund, Klaus; Biere, Armin; Koga, Dennis (Technical Monitor)

2003-01-01

Data races are a common problem in concurrent and multi-threaded programming. They are hard to detect without proper tool support. Despite the successful application of these tools, experience shows that the notion of data race is not powerful enough to capture certain types of inconsistencies occurring in practice. In this paper we investigate data races on a higher abstraction layer. This enables us to detect inconsistent uses of shared variables, even if no classical race condition occurs. For example, a data structure representing a coordinate pair may have to be treated atomically. By lifting the meaning of a data race to a higher level, such problems can now be covered. The paper defines the concepts view and view consistency to give a notation for this novel kind of property. It describes what kinds of errors can be detected with this new definition, and where its limitations are. It also gives a formal guideline for using data structures in a multi-threading environment.

Determination of Ochratoxin A in wine by packed in-tube solid phase microextraction followed by high performance liquid chromatography coupled to tandem mass spectrometry.

PubMed

Andrade, Mariane A; Lanças, Fernando M

2017-04-14

Ochratoxin A (OTA), a widely studied mycotoxin, can be found in a variety of food matrices. As its concentration in food is generally low (in the order of μg kg -1 ), sample preparation techniques are necessary for the analyte purification and pre-concentration in order to achieve the required low detection limits. The separation and detection methods used for OTA analysis should also offer proper sensitivity in order to allow the adequate quantification of the analyte. This manuscript addresses the development of a methodology aiming the analysis of OTA in wine samples by packed in-tube SPME in flow through extraction mode coupled to HPLC-MS/MS. The in-tube SPME set up utilized a PEEK tube packed with C18 particles as the extraction column. The method was optimized by a central composite design 2 2 +3 extra central points, having as factors the percentage of ACN and time in the sample load step. The functionalities of the method were attested and its analytical conditions, enhanced by using 22% of ACN and 6min in the sample load step. Validation of the method was also accomplished prior to analyses of both dry red wine and dry white wine samples. The method demonstrated proper sensitivity, with detection and quantification limits equal to 0.02 and 0.05μgL -1 , respectively. Linearity and precision exhibited a 0.996 correlation coefficient and RSD under 6%, respectively. The method proved to be accurate at medium and higher concentration levels with a maximum recovery of 73% at higher concentration levels. OTA was not detected in either dry red and dry white wine samples evaluated in this work. If present, it would be at concentrations lower than the detection and quantification limits established for the proposed method, and considered not a potential danger to human health according to our present knowledge. Copyright © 2017 Elsevier B.V. All rights reserved.

Sensitive detection of chlorine in iron oxide by single pulse and dual pulse laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Pedarnig, J. D.; Haslinger, M. J.; Bodea, M. A.; Huber, N.; Wolfmeir, H.; Heitz, J.

2014-11-01

The halogen chlorine is hard to detect in laser-induced breakdown spectroscopy (LIBS) mainly due to its high excited state energies of 9.2 and 10.4 eV for the most intense emission lines at 134.72 nm and 837.59 nm, respectively. We report on sensitive detection of Cl in industrial iron oxide Fe2O3 powder by single-pulse (SP) and dual-pulse (DP) LIBS measurements in the near infrared range in air. In compacted powder measured by SP excitation (Nd:YAG laser, 532 nm) Cl was detected with limit of detection LOD = 440 ppm and limit of quantitation LOQ = 720 ppm. Orthogonal DP LIBS was studied on pressed Fe2O3 pellets and Fe3O4 ceramics. The transmission of laser-induced plasma for orthogonal Nd:YAG 1064 nm and ArF 193 nm laser pulses showed a significant dependence on interpulse delay time (ipd) and laser wavelength (λL). The UV pulses (λL = 193 nm) were moderately absorbed in the plasma and the Cl I emission line intensity was enhanced while IR pulses (λL = 1064 nm) were not absorbed and Cl signals were not enhanced at ipd = 3 μs. The UV laser enhancement of Cl signals is attributed to the much higher signal/background ratio for orthogonal DP excitation compared to SP excitation and to the increased plasma temperature and electron number density. This enabled measurement at a very short delay time of td ≥ 0.1 μs with respect to the re-excitation pulse and detection of the very rapidly decaying Cl emission with higher efficiency.

Effects of liquid chromatography mobile phases and buffer salts on phosphorus inductively coupled plasma atomic emission and mass spectrometries utilizing ultrasonic nebulization and membrane desolvation.

PubMed

Carr, John E; Kwok, Kaho; Webster, Gregory K; Carnahan, Jon W

2006-01-23

Atomic spectrometry, specifically inductively coupled plasma atomic emission spectrometry (ICP-AES) and mass spectrometry (ICP-MS) show promise for heteroatom-based detection of pharmaceutical compounds. The combination of ultrasonic nebulization (USN) with membrane desolvation (MD) greatly enhances detection limits with these approaches. Because pharmaceutical analyses often incorporate liquid chromatography, the study herein was performed to examine the effects of solvent composition on the analytical behaviors of these approaches. The target analyte was phosphorus, introduced as phosphomycin. AES response was examined at the 253.7 nm atom line and mass 31 ions were monitored for the MS experiments. With pure aqueous solutions, detection limits of 5 ppb (0.5 ng in 0.1 mL injection volumes) were obtained with ICP-MS. The ICP-AES detection limit was 150 ppb. Solvent compositions were varied from 0 to 80% organic (acetonitrile and methanol) with nine buffers at concentrations typically used in liquid chromatography. In general, solvents and buffers had statistically significant, albeit small, effects on ICP-AES sensitivities. A few exceptions occurred in cases where typical liquid chromatography buffer concentrations produced higher mass loadings on the plasma. Indications are that isocratic separations can be reliably performed. Within reasonable accuracy tolerances, it appears that gradient chromatography can be performed without the need for signal response normalization. Organic solvent and buffer effects were more significant with ICP-MS. Sensitivities varied significantly with different buffers and organic solvent content. In these cases, gradient chromatography will require careful analytical calibration as solvent and buffer content is varied. However, for most buffer and solvent combinations, signal and detection limits are only moderately affected. Isocratic separations and detection are feasible.

Annoyance, detection and recognition of wind turbine noise.

PubMed

Van Renterghem, Timothy; Bockstael, Annelies; De Weirt, Valentine; Botteldooren, Dick

2013-07-01

Annoyance, recognition and detection of noise from a single wind turbine were studied by means of a two-stage listening experiment with 50 participants with normal hearing abilities. In-situ recordings made at close distance from a 1.8-MW wind turbine operating at 22 rpm were mixed with road traffic noise, and processed to simulate indoor sound pressure levels at LAeq 40 dBA. In a first part, where people were unaware of the true purpose of the experiment, samples were played during a quiet leisure activity. Under these conditions, pure wind turbine noise gave very similar annoyance ratings as unmixed highway noise at the same equivalent level, while annoyance by local road traffic noise was significantly higher. In a second experiment, listeners were asked to identify the sample containing wind turbine noise in a paired comparison test. The detection limit of wind turbine noise in presence of highway noise was estimated to be as low as a signal-to-noise ratio of -23 dBA. When mixed with local road traffic, such a detection limit could not be determined. These findings support that noticing the sound could be an important aspect of wind turbine noise annoyance at the low equivalent levels typically observed indoors in practice. Participants that easily recognized wind-turbine(-like) sounds could detect wind turbine noise better when submersed in road traffic noise. Recognition of wind turbine sounds is also linked to higher annoyance. Awareness of the source is therefore a relevant aspect of wind turbine noise perception which is consistent with previous research. Copyright © 2013 Elsevier B.V. All rights reserved.

Fast fMRI can detect oscillatory neural activity in humans.

PubMed

Lewis, Laura D; Setsompop, Kawin; Rosen, Bruce R; Polimeni, Jonathan R

2016-10-25

Oscillatory neural dynamics play an important role in the coordination of large-scale brain networks. High-level cognitive processes depend on dynamics evolving over hundreds of milliseconds, so measuring neural activity in this frequency range is important for cognitive neuroscience. However, current noninvasive neuroimaging methods are not able to precisely localize oscillatory neural activity above 0.2 Hz. Electroencephalography and magnetoencephalography have limited spatial resolution, whereas fMRI has limited temporal resolution because it measures vascular responses rather than directly recording neural activity. We hypothesized that the recent development of fast fMRI techniques, combined with the extra sensitivity afforded by ultra-high-field systems, could enable precise localization of neural oscillations. We tested whether fMRI can detect neural oscillations using human visual cortex as a model system. We detected small oscillatory fMRI signals in response to stimuli oscillating at up to 0.75 Hz within single scan sessions, and these responses were an order of magnitude larger than predicted by canonical linear models. Simultaneous EEG-fMRI and simulations based on a biophysical model of the hemodynamic response to neuronal activity suggested that the blood oxygen level-dependent response becomes faster for rapidly varying stimuli, enabling the detection of higher frequencies than expected. Accounting for phase delays across voxels further improved detection, demonstrating that identifying vascular delays will be of increasing importance with higher-frequency activity. These results challenge the assumption that the hemodynamic response is slow, and demonstrate that fMRI has the potential to map neural oscillations directly throughout the brain.

Enhanced dopamine detection sensitivity by PEDOT/graphene oxide coating on in vivo carbon fiber electrodes.

PubMed

Taylor, I Mitch; Robbins, Elaine M; Catt, Kasey A; Cody, Patrick A; Happe, Cassandra L; Cui, Xinyan Tracy

2017-03-15

Dopamine (DA) is a monoamine neurotransmitter responsible for regulating a variety of vital life functions. In vivo detection of DA poses a challenge due to the low concentration and high speed of physiological signaling. Fast scan cyclic voltammetry at carbon fiber microelectrodes (CFEs) is an effective method to monitor real-time in vivo DA signaling, however the sensitivity is somewhat limited. Electrodeposition of poly(3,4-ethylene dioxythiophene) (PEDOT)/graphene oxide (GO) onto the CFE surface is shown to increase the sensitivity and lower the limit of detection for DA compared to bare CFEs. Thicker PEDOT/GO coatings demonstrate higher sensitivities for DA, but display the negative drawback of slow adsorption and electron transfer kinetics. The moderate thickness resulting from 25 s electrodeposition of PEDOT/GO produces the optimal electrode, exhibiting an 880% increase in sensitivity, a 50% decrease in limit of detection and minimally altered electrode kinetics. PEDOT/GO coated electrodes rapidly and robustly detect DA, both in solution and in the rat dorsal striatum. This increase in DA sensitivity is likely due to increasing the electrode surface area with a PEDOT/GO coating and improved adsorption of DA's oxidation product (DA-o-quinone). Increasing DA sensitivity without compromising electrode kinetics is expected to significantly improve our understanding of the DA function in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhanced Dopamine Detection Sensitivity by PEDOT/Graphene Oxide Coating on in vivo Carbon Fiber Electrodes

PubMed Central

Taylor, I. Mitch; Robbins, Elaine M.; Catt, Kasey A.; Cody, Patrick A.; Weaver, Cassandra L.; Cui, Xinyan Tracy

2016-01-01

Dopamine (DA) is a monoamine neurotransmitter responsible for regulating a variety of vital life functions. In vivo detection of DA poses a challenge due to the low concentration and high speed of physiological signaling. Fast scan cyclic voltammetry at carbon fiber microelectrodes (CFEs) is an effective method to monitor real-time in vivo DA signaling, however the sensitivity is somewhat limited. Electrodeposition of poly(3,4-ethylene dioxythiophene) (PEDOT)/graphene oxide (GO) onto the CFE surface is shown to increase the sensitivity and lower the limit of detection for DA compared to bare CFEs. Thicker PEDOT/GO coatings demonstrate higher sensitivities for DA, but display the negative drawback of slow adsorption and electron transfer kinetics. The moderate thickness resulting from 25 s electrodeposition of PEDOT/GO produces the optimal electrode, exhibiting an 880% increase in sensitivity, a 50% decrease in limit of detection and minimally altered electrode kinetics. PEDOT/GO coated electrodes rapidly and robustly detect DA, both in solution and in the rat dorsal striatum. This increase in DA sensitivity is likely due to increasing the electrode surface area with a PEDOT/GO coating and improved adsorption of DA’s oxidation product (DA-o-quinone). Increasing DA sensitivity without compromising electrode kinetics is expected to significantly improve our understanding of the DA function in vivo. PMID:27268013

Characteristics of right-sided colonic neoplasia and colonoscopy barriers limiting their early detection and prognosis: a review of the literature.

PubMed

Fischbach, Wolfgang; Elsome, Rory; Amlani, Bharat

2018-06-05

Colonoscopy provides less protection from colorectal cancer in the right colon than the left. Areas covered: This review examines patient outcomes and colonoscopy success rates to identify factors that limit the protective effect of colonoscopy in the right colon. The MEDLINE and Embase databases were searched for literature from 2000 onwards, on the long-term outcomes and differences in screening practice between the right and left colon. In total, 12 systematic reviews (including nine meta-analyses) and 44 primary data records were included. Differences in patient outcomes and colonoscopy practice were identified between the right and left colon, suggesting that several factors, many of which disproportionally affect the right colon, impact lesion detection rates. Shorter withdrawal times reduce detection rates, while longer times significantly increase detection; mostly of adenomas in the right colon. Colonoscope attachments often only show a significant improvement in detection rates in the right colon, suggesting detection is more challenging due to visibility of the right colonic mucosa. Higher bowel cleansing grades significantly improve detection rates in the right colon compared to the left. Expert commentary: These findings confirm the need for continued improvement of colonoscopy effectiveness, and obligatory quality assessment, overall and especially in the right colon.

A Validation of Remotely Sensed Fires Using Ground Reports

NASA Astrophysics Data System (ADS)

Ruminski, M. G.; Hanna, J.

2007-12-01

A satellite based analysis of fire detections and smoke emissions for North America is produced daily by NOAA/NESDIS. The analysis incorporates data from the MODIS (Terra and Aqua) and AVHRR (NOAA-15/16/17) polar orbiting instruments and GOES East and West geostationary spacecraft with nominal resolutions of 1km and 4 km for the polar and geostationary platforms respectively. Automated fire detection algorithms are utilized for each of the sensors. Analysts perform a quality control procedure on the automated detects by deleting points that are deemed to be false detects and adding points that the algorithms did not detect. A limited validation of the final quality controlled product was performed using high resolution (30 m) ASTER data in the summer of 2006. Some limitations in using ASTER data are that each scene is only approximately 3600 square km, the data acquisition time is relatively constant at around 1030 local solar time and ASTER is another remotely sensed data source. This study expands on the ASTER validation by using ground reports of prescribed burns in Montana and Idaho for 2003 and 2004. It provides a non-remote sensing data source for comparison. While the ground data do not have the limitations noted above for ASTER there are still limitations. For example, even though the data set covers a much larger area (nearly 600,000 square km) than even several ASTER scenes, it still represents a single region of North America. And while the ground data are not restricted to a narrow time window, only a date is provided with each report, limiting the ability to make detailed conclusions about the detection capabilities for specific instruments, especially for the less temporally frequent polar orbiting MODIS and AVHRR sensors. Comparison of the ground data reports to the quality controlled fire analysis revealed a low rate of overall detection of 23.00% over the entire study period. Examination of the daily detection rates revealed a wide variation, with some days resulting in as little as 5 detects out of 107 reported fires while other days had as many as 84 detections out of 160 reports. Inspection of the satellite imagery from the days with very low detection rates revealed that extensive cloud cover prohibited satellite fire detection. On days when cloud cover was at a minimum, detection rates were substantially higher. An estimate of the fire size was also provided with the ground data set. Statistics will be presented for days with minimal cloud cover which will indicate the probability of detection for fires of various sizes.

Constraining Accretion Signatures of Exoplanets in the TW Hya Transitional Disk

NASA Astrophysics Data System (ADS)

Uyama, Taichi; Tanigawa, Takayuki; Hashimoto, Jun; Tamura, Motohide; Aoyama, Yuhiko; Brandt, Timothy D.; Ishizuka, Masato

2017-09-01

We present a near-infrared direct imaging search for accretion signatures of possible protoplanets around the young stellar object (YSO) TW Hya, a multi-ring disk exhibiting evidence of planet formation. The Paβ line (1.282 μm) is an indication of accretion onto a protoplanet, and its intensity is much higher than that of blackbody radiation from the protoplanet. We focused on the Paβ line and performed Keck/OSIRIS spectroscopic observations. Although spectral differential imaging (SDI) reduction detected no accretion signatures, the results of the present study allowed us to set 5σ detection limits for Paβ emission of 5.8 × 10-18 and 1.5 × 10-18 erg-1 s-1 cm-2 at 0.″4 and 1.″6, respectively. We considered the mass of potential planets using theoretical simulations of circumplanetary disks and hydrogen emission. The resulting masses were 1.45 ± 0.04 M J and {2.29}-0.04+0.03 {M}{{J}} at 25 and 95 au, respectively, which agree with the detection limits obtained from previous broadband imaging. The detection limits should allow for the identification of protoplanets as small as ˜1 M J, which may assist in direct imaging searches around faint YSOs for which extreme adaptive optics instruments are unavailable.

Occurrence of perchlorate in groundwater, paired farmland soil, lettuce, and rhizosphere soil from Chengdu, China.

PubMed

Tang, Yulu; Zhong, Bifeng; Qu, Bing; Feng, Shujin; Ding, Sanglan; Su, Shijun; Li, Zhi; Gan, Zhiwei

2017-05-24

A total of 28 groundwater, paired farmland soil, lettuce, and its rhizosphere soil samples were collected from Chengdu, China to detect perchlorate levels and to evaluate the relationships of perchlorate concentrations among these matrices. The perchlorate concentrations in the groundwater, farmland soil, lettuce, and rhizosphere soil samples ranged from below detection limit to 60.2 μg L -1 , from below detection limit to 249 μg kg -1 dry weight (dw), from 2.07 to 1010 μg kg -1 wet weight, and from below detection limit to 314 μg kg -1 dw, respectively. Significant correlation was found in the perchlorate levels among the farmland soil, lettuce, and rhizosphere soil, suggesting that they have common pollution sources, or perchlorate might transfer from farmland soil-rhizosphere soil-plant. However, there is no significant correlation between groundwater and the other three matrices, indicating that infiltration from perchlorate contaminated farmland soil was not the predominant source for groundwater pollution in Chengdu. The perchlorate concentrations in the farmland soil and lettuce samples were significantly higher than those in the rhizosphere soil, primarily due to uptake of perchlorate through the rhizosphere micro-environment by lettuce, or accelerated degradation by rhizospheric microorganisms, which contributed more needs further investigation.

Determination of primary aromatic amines in cold water extract of coloured paper napkin samples by liquid chromatography-tandem mass spectrometry.

PubMed

Yavuz, Oguzhan; Valzacchi, Sandro; Hoekstra, Eddo; Simoneau, Catherine

2016-06-01

The aim of this study was the optimisation of a multi-analyte method for the analysis of primary aromatic amines (PAAs) from napkins in order to support official controls and food safety. We developed a UHPLC-MS/MS method for the simultaneous determination of 36 toxicologically relevant PAAs for paper and board. Good regression coefficients of the calibration curves in a range of 0.992-0.999 and reproducibilities in a range of 2.3-15% were obtained. Limits of detections (LODs) were in the range of 0.03-1.4 µg l(-1) and recoveries were in a range of 21-110% for all the amines. A total of 93 coloured paper napkin samples from different European countries were bought and extracted with water to determine the PAAs. The results showed that 42 of 93 samples contained at least one PAA. More than half of the detected PAAs are considered as toxic, carcinogenic or probably carcinogenic to humans by the International Agency for Research on Cancer (IARC), or are classified as such in the European Union legislation on chemicals. Summed concentrations of PAAs in seven samples were higher than 10 µg l(-1), the limit of summed PAA in the European Union plastic food contact material regulation. Also, eight PAAs, classified as Category 1A and 1B carcinogen in the European Union legislation of chemicals, were detected at concentrations higher than 2 µg l(-1), exceeding the limit proposed by the Federal Institute for Risk Assessment in Germany. Aniline (n = 14) was most frequently present in higher concentrations followed by o-toluidine, o-anisidine, 2,4-dimethylaniline and 4-aminoazobenzene. Red, orange, yellow and multicoloured paper napkins contained the highest concentrations of total PAAs (> 10 µg l(-1)). Although the European Union has not harmonised the legislation of paper and board materials and, thus, there is no specific migration limit for PAAs from paper napkins, the present study showed that coloured paper napkins can contain toxic and carcinogenic PAAs at concentrations that are relevant for monitoring.

Validation of the AUDIT-C in adults seeking help with their drinking online.

PubMed

Khadjesari, Zarnie; White, Ian R; McCambridge, Jim; Marston, Louise; Wallace, Paul; Godfrey, Christine; Murray, Elizabeth

2017-01-04

The abbreviated Alcohol Use Disorder Identification Test for Consumption (AUDIT-C) is rapidly becoming the alcohol screening tool of choice for busy practitioners in clinical settings and by researchers keen to limit assessment burden and reactivity. Cut-off scores for detecting drinking above recommended limits vary by population, setting, country and potentially format. This validation study aimed to determine AUDIT-C thresholds that indicated risky drinking among a population of people seeking help over the Internet. The data in this study were collected in the pilot phase of the Down Your Drink trial, which recruited people seeking help over the Internet and randomised them to a web-based intervention or an information-only website. Sensitivity, specificity, and positive and negative likelihood ratios were calculated for AUDIT-C scores, relative to weekly consumption that indicated drinking above limits and higher risk drinking. Receiver-operating characteristic (ROC) curves were created to assess the performance of different cut-off scores on the AUDIT-C for men and women. Past week alcohol consumption was used as the reference-standard and was collected via the TOT-AL, a validated online measure of past week drinking. AUDIT-C scores were obtained from 3720 adults (2053 female and 1667 male) searching the internet for help with drinking, mostly from the UK. The area under the ROC curve for risky drinking was 0.84 (95% CI 0.80, 0.87) (female) and 0.80 (95% CI 0.76, 0.84) (male). AUDIT-C cut-off scores for detecting risky drinking that maximise the sum of sensitivity and specificity were ≥8 for women and ≥8 for men; whereas those identifying the highest proportion of correctly classified individuals were ≥4 for women and ≥5 for men. AUDIT-C cut-off scores for detecting higher risk drinking were also calculated. AUDIT-C cut-off scores for identifying alcohol consumption above weekly limits in this largely UK based study population were substantially higher than those reported in other validation studies. Researchers and practitioners should select AUDIT-C cut-off scores according to the purpose of identifying risky drinkers and hence the relative importance of sensitivity and/or specificity.

An uncertainty-based distributed fault detection mechanism for wireless sensor networks.

PubMed

Yang, Yang; Gao, Zhipeng; Zhou, Hang; Qiu, Xuesong

2014-04-25

Exchanging too many messages for fault detection will cause not only a degradation of the network quality of service, but also represents a huge burden on the limited energy of sensors. Therefore, we propose an uncertainty-based distributed fault detection through aided judgment of neighbors for wireless sensor networks. The algorithm considers the serious influence of sensing measurement loss and therefore uses Markov decision processes for filling in missing data. Most important of all, fault misjudgments caused by uncertainty conditions are the main drawbacks of traditional distributed fault detection mechanisms. We draw on the experience of evidence fusion rules based on information entropy theory and the degree of disagreement function to increase the accuracy of fault detection. Simulation results demonstrate our algorithm can effectively reduce communication energy overhead due to message exchanges and provide a higher detection accuracy ratio.

Cicada wing decorated by silver nanoparticles as low-cost and active/sensitive substrates for surface-enhanced Raman scattering

NASA Astrophysics Data System (ADS)

Guo, Lei; Zhang, Chang Xing; Deng, Li; Zhang, Guo Xin; Xu, Hai Jun; Sun, Xiao Ming

2014-06-01

A green, low-cost and highly efficient surface-enhanced Raman scattering (SERS) substrate was achieved by a chemical deposition of silver nanoparticles on a cicada wing, which has the large-scale nanosized protrusions on its surface. Employing the already-formed Ag/cicada wing as substrate for SERS detection, the detection limit for rhodamine 6G could reach 10-7M, the Raman enhancement factor of the substrate was as large as 106 and the relative standard deviation remains lower than 7%. The three-dimensional finite-difference time-domain simulation results showed that two types of inter-Ag-nanoparticle nanogaps in the formed geometry created a huge number of SERS "hot spots" where the electromagnetic field is substantially amplified and contributes to the higher SERS sensitivity. Meanwhile, the water contact angle of the SERS substrate is roughly 150°, which indicates the super-hydrophobic surface of the substrate. This feature may be conducive to the gathering of target molecules during the SERS detection, which in turn further improves the detection limit of target molecules. In order to improve the application of the substrate, thiram was used as the probe molecule, and the detection limit also reached 10-7 M. Meanwhile, the calibration of the Raman peak intensities of Rhodamine 6G and thiram allowed their quantitative detection. Therefore, the green and low-cost SERS substrates could be used for fast and quantitative detection of trace organic molecules. Our findings may contribute to the development of the green and low-cost SERS substrates and will allow the fast and quantitative detection of trace organic molecules.

Rapid and sensitive detection of Zika virus by reverse transcription loop-mediated isothermal amplification.

PubMed

Wang, Xuan; Yin, Fenggui; Bi, Yuhai; Cheng, Gong; Li, Jing; Hou, Lidan; Li, Yunlong; Yang, Baozhi; Liu, Wenjun; Yang, Limin

2016-12-01

Zika virus (ZIKV) is an arbovirus that recently emerged and has expanded worldwide, causing a global threat and raising international concerns. Current molecular diagnostics, e.g., real-time PCR and reverse transcription PCR (RT-PCR), are time consuming, expensive, and can only be deployed in a laboratory instead of for field diagnostics. This study aimed to develop a one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) platform showing sensitivity, specificity, and more convenience than previous methods, being easily distributed and implemented. Specific primers were designed and screened to target the entire ZIKV genome. The analytical sensitivity and specificity of the assay were evaluated and compared with traditional PCR and quantitative real-time PCR. Three different simulated clinical sample quick preparation protocols were evaluated to establish a rapid and straightforward treatment procedure for clinical specimens in open field detection. The RT-LAMP assay for detection of ZIKV demonstrated superior specificity and sensitivity compared to traditional PCR at the optimum reaction temperature. For the ZIKV RNA standard, the limit of detection was 20 copies/test. For the simulated ZIKV clinical samples, the limit of detection was 0.02 pfu/test, which was one order of magnitude higher than RT-PCR and similar to real-time PCR. The detection limit of simulated ZIKV specimens prepared using a protease quick processing method was consistent with that of samples prepared using commercial nucleic acid extraction kits, indicating that our ZIKV detection method could be used in point-of-care testing. The RT-LAMP assay had excellent sensitivity and specificity for detecting ZIKV and can be deployed together with a rapid specimen processing method, offering the possibility for ZIKV diagnosis outside of the laboratory. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of atmospheric properties on detection of wood-warbler nocturnal flight calls

NASA Astrophysics Data System (ADS)

Horton, Kyle G.; Stepanian, Phillip M.; Wainwright, Charlotte E.; Tegeler, Amy K.

2015-10-01

Avian migration monitoring can take on many forms; however, monitoring active nocturnal migration of land birds is limited to a few techniques. Avian nocturnal flight calls are currently the only method for describing migrant composition at the species level. However, as this method develops, more information is needed to understand the sources of variation in call detection. Additionally, few studies examine how detection probabilities differ under varying atmospheric conditions. We use nocturnal flight call recordings from captive individuals to explore the dependence of flight call detection on atmospheric temperature and humidity. Height or distance from origin had the largest influence on call detection, while temperature and humidity also influenced detectability at higher altitudes. Because flight call detection varies with both atmospheric conditions and flight height, improved monitoring across time and space will require correction for these factors to generate standardized metrics of songbird migration.

Poly(3-Methylthiophene) Thin Films Deposited Electrochemically on QCMs for the Sensing of Volatile Organic Compounds

PubMed Central

Öztürk, Sadullah; Kösemen, Arif; Şen, Zafer; Kılınç, Necmettin; Harbeck, Mika

2016-01-01

Poly(3-methylthiophene) (PMeT) thin films were electrochemically deposited on quartz crystal microbalance QCM transducers to investigate their volatile organic compound (VOC) sensing properties depending on ambient conditions. Twelve different VOCs including alcohols, ketones, chlorinated compounds, amines, and the organosphosphate dimethyl methylphosphonate (DMMP) were used as analytes. The responses of the chemical sensors against DMMP were the highest among the tested analytes; thus, fabricated chemical sensors based on PMeT can be evaluated as potential candidates for selectively detecting DMMP. Generally, detection limits in the low ppm range could be achieved. The gas sensing measurements were recorded at various humid air conditions to investigate the effects of the humidity on the gas sensing properties. The sensing performance of the chemical sensors was slightly reduced in the presence of humidity in ambient conditions. While a decrease in sensitivity was observed for humidity levels up to 50% r.h., the sensitivity was nearly unaffected for higher humidity levels and a reliable detection of the VOCs and DMMP was possible with detection limits in the low ppm range. PMID:27023539

Sensitivity of gravitational wave searches to the full signal of intermediate-mass black hole binaries during the first observing run of Advanced LIGO

NASA Astrophysics Data System (ADS)

Calderón Bustillo, Juan; Salemi, Francesco; Dal Canton, Tito; Jani, Karan P.

2018-01-01

The sensitivity of gravitational wave searches for binary black holes is estimated via the injection and posterior recovery of simulated gravitational wave signals in the detector data streams. When a search reports no detections, the estimated sensitivity is then used to place upper limits on the coalescence rate of the target source. In order to obtain correct sensitivity and rate estimates, the injected waveforms must be faithful representations of the real signals. Up to date, however, injected waveforms have neglected radiation modes of order higher than the quadrupole, potentially biasing sensitivity and coalescence rate estimates. In particular, higher-order modes are known to have a large impact in the gravitational waves emitted by intermediate-mass black holes binaries. In this work, we evaluate the impact of this approximation in the context of two search algorithms run by the LIGO Scientific Collaboration in their search for intermediate-mass black hole binaries in the O1 LIGO Science Run data: a matched filter-based pipeline and a coherent unmodeled one. To this end, we estimate the sensitivity of both searches to simulated signals for nonspinning binaries including and omitting higher-order modes. We find that omission of higher-order modes leads to biases in the sensitivity estimates which depend on the masses of the binary, the search algorithm, and the required level of significance for detection. In addition, we compare the sensitivity of the two search algorithms across the studied parameter space. We conclude that the most recent LIGO-Virgo upper limits on the rate of coalescence of intermediate-mass black hole binaries are conservative for the case of highly asymmetric binaries. However, the tightest upper limits, placed for nearly equal-mass sources, remain unchanged due to the small contribution of higher modes to the corresponding sources.

[Antimony and other heavy metals in metallic kitchen ware].

PubMed

Ishiwata, H; Sugita, T; Yoshihira, K

1989-01-01

The antimony in metallic kitchen ware was determined. The content of this element in metals used for the production or repairing of utensils, containers and packaging which come in contact with foods is regulated and should be less than 5% in under the Japanese Food Sanitation Law. In eight metallic samples, antimony was detected in solder used for the production of a can for green tea and an eggbeater. The contents were 1.30% in the former and 1.90% in the latter. No antimony was detected in solder used for a cookie cutter. A sample of solder used for electric work, not for food utensils, contained 0.81% of antimony. In other metallic utensils which come in contact with food such as aluminum foil, a brass spoon, a stainless steel fork, a wire netting, and an iron rock for vegetable color stabilizing, antimony was not detected at a 0.05% detection limit. A qualitative test using rhodamine B also showed positive results in only three solder samples. Lead concentrations in solder used for the kitchen ware were from 39.3 to 51.3%. These concentrations were higher than the limit (20%) of lead content by the Law. No cadmium was detected in any samples.

High-sensitivity detection of biological amines using fast Hadamard transform CE coupled with photolytic optical gating.

PubMed

Braun, Kevin L; Hapuarachchi, Suminda; Fernandez, Facundo M; Aspinwall, Craig A

2007-08-01

Here, we report the first utilization of Hadamard transform CE (HTCE), a high-sensitivity, multiplexed CE technique, with photolytic optical gating sample injection of caged fluorescent labels for the detection of biologically important amines. Previous implementations of HTCE have relied upon photobleaching optical gating sample injection of fluorescent dyes. Photolysis of caged fluorescent labels reduces the fluorescence background, providing marked enhancements in sensitivity compared to photobleaching. Application of fast Hadamard transform CE (fHTCE) for fluorescein-based dyes yields a ten-fold higher sensitivity for photolytic injections compared to photobleaching injections, due primarily to the reduced fluorescent background provided by caged fluorescent dyes. Detection limits as low as 5 pM (ca. 18 molecules per injection event) were obtained with on-column LIF detection using fHTCE in less than 25 s, with the capacity for continuous, online separations. Detection limits for glutamate and aspartate below 150 pM (1-2 amol/injection event) were obtained using photolytic sample injection, with separation efficiencies exceeding 1 x 10(6) plates/m and total multiplexed separation times as low as 8 s. These results strongly support the feasibility of this approach for high-sensitivity dynamic chemical monitoring applications.

Parallel heuristics for scalable community detection

DOE PAGES

Lu, Hao; Halappanavar, Mahantesh; Kalyanaraman, Ananth

2015-08-14

Community detection has become a fundamental operation in numerous graph-theoretic applications. Despite its potential for application, there is only limited support for community detection on large-scale parallel computers, largely owing to the irregular and inherently sequential nature of the underlying heuristics. In this paper, we present parallelization heuristics for fast community detection using the Louvain method as the serial template. The Louvain method is an iterative heuristic for modularity optimization. Originally developed in 2008, the method has become increasingly popular owing to its ability to detect high modularity community partitions in a fast and memory-efficient manner. However, the method ismore » also inherently sequential, thereby limiting its scalability. Here, we observe certain key properties of this method that present challenges for its parallelization, and consequently propose heuristics that are designed to break the sequential barrier. For evaluation purposes, we implemented our heuristics using OpenMP multithreading, and tested them over real world graphs derived from multiple application domains. Compared to the serial Louvain implementation, our parallel implementation is able to produce community outputs with a higher modularity for most of the inputs tested, in comparable number or fewer iterations, while providing real speedups of up to 16x using 32 threads.« less

Low contrast detection in abdominal CT: comparing single-slice and multi-slice tasks

NASA Astrophysics Data System (ADS)

Ba, Alexandre; Racine, Damien; Viry, Anaïs.; Verdun, Francis R.; Schmidt, Sabine; Bochud, François O.

2017-03-01

Image quality assessment is crucial for the optimization of computed tomography (CT) protocols. Human and mathematical model observers are increasingly used for the detection of low contrast signal in abdominal CT, but are frequently limited to the use of a single image slice. Another limitation is that most of them only consider the detection of a signal embedded in a uniform background phantom. The purpose of this paper was to test if human observer performance is significantly different in CT images read in single or multiple slice modes and if these differences are the same for anatomical and uniform clinical images. We investigated detection performance and scrolling trends of human observers of a simulated liver lesion embedded in anatomical and uniform CT backgrounds. Results show that observers don't take significantly benefit of additional information provided in multi-slice reading mode. Regarding the background, performances are moderately higher for uniform than for anatomical images. Our results suggest that for low contrast detection in abdominal CT, the use of multi-slice model observers would probably only add a marginal benefit. On the other hand, the quality of a CT image is more accurately estimated with clinical anatomical backgrounds.

Enhancement of Localized Surface Plasmon Resonance polymer based biosensor chips using well-defined glycopolymers for lectin detection.

PubMed

Jin, Yan; Wong, Kok Hou; Granville, Anthony Michael

2016-01-15

Poly(methyl methacrylate) polymer based Localized Surface Plasmon Resonance biosensor chips were successfully fabricated using glycopolymer brushes carrying glucose moieties for the detection of concanavalin A. Poly(pentafluorostyrene), with pre-determined polymer chain lengths, were synthesized via a reversible addition-fragmentation chain transfer polymerization technique. The synthesized poly(pentafluorostyrene), was subsequently converted into glycopolymers via a para-fluoro-thiol "click" reaction and grafted onto the surface of sensor chips. The "glycocluster effect" induced by pendent carbohydrate moieties enabled a stronger affinity for concanavalin A binding, which resulted in a dramatic expansion of the sensors' response range. It was discovered that the longer polymer brushes did not guarantee additional enhancements for the sensor chips. Instead, they could lead to higher detection limits. In this study, the limit of detection for the sensor chips was discovered to be 1.3nmolL(-1) with a saturated response at 1054.2nmolL(-1). In addition to the superior performance, the capabilities of the reported sensor chips can be easily manipulated to detect a diverse range of analytes by "clicking" various sensing elements onto the polymer brushes. Copyright © 2015 Elsevier Inc. All rights reserved.

Development of a chemiluminescence competitive PCR for the detection and quantification of parvovirus B19 DNA using a microplate luminometer.

PubMed

Fini, F; Gallinella, G; Girotti, S; Zerbini, M; Musiani, M

1999-09-01

Quantitative PCR of viral nucleic acids can be useful clinically in diagnosis, risk assessment, and monitoring of antiviral therapy. We wished to develop a chemiluminescence competitive PCR (cPCR) for parvovirus B19. Parvovirus DNA target sequences and competitor sequences were coamplified and directly labeled. Amplified products were then separately hybridized by specific biotin-labeled probes, captured onto streptavidin-coated ELISA microplates, and detected immunoenzymatically using chemiluminescent substrates of peroxidase. Chemiluminescent signals were quantitatively analyzed by a microplate luminometer and were correlated to the amounts of amplified products. Luminol-based systems displayed constant emission but had a higher detection limit (100-1000 genome copies) than the acridan-based system (20 genome copies). The detection limit of chemiluminescent substrates was lower (20 genome copies) than colorimetric substrates (50 genome copies). In chemiluminescence cPCR, the titration curves showed linear correlation above 100 target genome copies. Chemiluminescence cPCR was positive in six serum samples from patients with parvovirus infections and negative in six control sera. The chemiluminescence cPCR appears to be a sensitive and specific method for the quantitative detection of viral DNAs.

Distribution and seasonal differences in Pacific Lamprey and Lampetra spp eDNA across 18 Puget Sound watersheds

USGS Publications Warehouse

Ostberg, Carl O.; Chase, Dorothy M.; Hayes, Michael C.; Duda, Jeffrey J.

2018-01-01

Lampreys have a worldwide distribution, are functionally important to ecological communities and serve significant roles in many cultures. In Pacific coast drainages of North America, lamprey populations have suffered large declines. However, lamprey population status and trends within many areas of this region are unknown and such information is needed for advancing conservation goals. We developed two quantitative PCR-based, aquatic environmental DNA (eDNA) assays for detection of Pacific Lamprey (Entosphenus tridentatus) and Lampetra spp, using locked nucleic acids (LNAs) in the probe design. We used these assays to characterize the spatial distribution of lamprey in 18 watersheds of Puget Sound, Washington, by collecting water samples in spring and fall. Pacific Lamprey and Lampetraspp were each detected in 14 watersheds and co-occurred in 10 watersheds. Lamprey eDNA detection rates were much higher in spring compared to fall. Specifically, the Pacific Lamprey eDNA detection rate was 3.5 times higher in spring and the Lampetra spp eDNA detection rate was 1.5 times higher in spring even though larval lamprey are present in streams year-round. This significant finding highlights the importance of seasonality on eDNA detection. Higher stream discharge in the fall likely contributed to reduced eDNA detection rates, although seasonal life history events may have also contributed. These eDNA assays differentiate Pacific Lamprey and Lampetra spp across much of their range along the west coast of North America. Sequence analysis indicates the Pacific Lamprey assay also targets other Entosphenus spp and indicates the Lampetra spp assay may have limited or no capability of detecting Lampetra in some locations south of the Columbia River Basin. Nevertheless, these assays will serve as a valuable tool for resource managers and have direct application to lamprey conservation efforts, such as mapping species distributions, occupancy modeling, and monitoring translocations and reintroductions.

Distribution and seasonal differences in Pacific Lamprey and Lampetra spp eDNA across 18 Puget Sound watersheds

PubMed Central

Hayes, Michael C.; Duda, Jeffrey J.

2018-01-01

Lampreys have a worldwide distribution, are functionally important to ecological communities and serve significant roles in many cultures. In Pacific coast drainages of North America, lamprey populations have suffered large declines. However, lamprey population status and trends within many areas of this region are unknown and such information is needed for advancing conservation goals. We developed two quantitative PCR-based, aquatic environmental DNA (eDNA) assays for detection of Pacific Lamprey (Entosphenus tridentatus) and Lampetra spp, using locked nucleic acids (LNAs) in the probe design. We used these assays to characterize the spatial distribution of lamprey in 18 watersheds of Puget Sound, Washington, by collecting water samples in spring and fall. Pacific Lamprey and Lampetra spp were each detected in 14 watersheds and co-occurred in 10 watersheds. Lamprey eDNA detection rates were much higher in spring compared to fall. Specifically, the Pacific Lamprey eDNA detection rate was 3.5 times higher in spring and the Lampetra spp eDNA detection rate was 1.5 times higher in spring even though larval lamprey are present in streams year-round. This significant finding highlights the importance of seasonality on eDNA detection. Higher stream discharge in the fall likely contributed to reduced eDNA detection rates, although seasonal life history events may have also contributed. These eDNA assays differentiate Pacific Lamprey and Lampetra spp across much of their range along the west coast of North America. Sequence analysis indicates the Pacific Lamprey assay also targets other Entosphenus spp and indicates the Lampetra spp assay may have limited or no capability of detecting Lampetra in some locations south of the Columbia River Basin. Nevertheless, these assays will serve as a valuable tool for resource managers and have direct application to lamprey conservation efforts, such as mapping species distributions, occupancy modeling, and monitoring translocations and reintroductions. PMID:29576966

A label-free aptamer-fluorophore assembly for rapid and specific detection of cocaine in biofluids.

PubMed

Roncancio, Daniel; Yu, Haixiang; Xu, Xiaowen; Wu, Shuo; Liu, Ran; Debord, Joshua; Lou, Xinhui; Xiao, Yi

2014-11-18

We report a rapid and specific aptamer-based method for one-step cocaine detection with minimal reagent requirements. The feasibility of aptamer-based detection has been demonstrated with sensors that operate via target-induced conformational change mechanisms, but these have generally exhibited limited target sensitivity. We have discovered that the cocaine-binding aptamer MNS-4.1 can also bind the fluorescent molecule 2-amino-5,6,7-trimethyl-1,8-naphthyridine (ATMND) and thereby quench its fluorescence. We subsequently introduced sequence changes into MNS-4.1 to engineer a new cocaine-binding aptamer (38-GC) that exhibits higher affinity to both ligands, with reduced background signal and increased signal gain. Using this aptamer, we have developed a new sensor platform that relies on the cocaine-mediated displacement of ATMND from 38-GC as a result of competitive binding. We demonstrate that our sensor can detect cocaine within seconds at concentrations as low as 200 nM, which is 50-fold lower than existing assays based on target-induced conformational change. More importantly, our assay achieves successful cocaine detection in body fluids, with a limit of detection of 10.4, 18.4, and 36 μM in undiluted saliva, urine, and serum samples, respectively.

Detection of radio emission from optically identified supernova remnants in M31

NASA Technical Reports Server (NTRS)

Dickel, J. R.; Dodorico, S.; Felli, M.; Dopita, M.

1982-01-01

The Very Large Array was used to conduct a radio search at a wavelength of 20 cm for ten optically identified supernova remnants (SNRs) in M31. Five SNRs were detected, and for the other objects, upper limits to the emission were determined. On the average, the surface brightness of an SNR in M31 appears to be fainter than that of an SNR in the Galaxy. It is suggested that the median surface brightness at a given diameter is higher in late-type spirals than in Sb systems.

Report on Analyses of WAC Samples of Evaporator Overheads - 2004

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oji, L

2005-03-18

In November and December of 2004, the Tank Farm submitted annual samples from 2F, 2H and 3H Evaporator Overhead streams for characterization to verify compliance with the new Effluent Treatment Facility (ETF) Waste Acceptance Criteria (WAC) and to look for organic species. With the exception of slightly high ammonia in the 2F evaporator overheads and high radiation control guide number for the 3H and 2F evaporator overhead samples, all the overheads samples were found to be in compliance with the Effluent Treatment Facility WAC. The ammonium concentration in the 2F-evaporator overhead, at 33 mg/L, was above the ETF waste watermore » collection tank (WWCT) limits of 28 mg/L. The RCG Number for the 3H and 2F evaporator samples at, respectively, 1.38E-02 and 8.24E-03 were higher than the WWCT limit of 7.69E-03. The analytical detection limits for americium-241 and radium-226 in the evaporator samples were not consistently met because of low WWCT detection limits and insufficient evaporator samples.« less

Cryogen-free heterodyne-enhanced mid-infrared Faraday rotation spectrometer

PubMed Central

Wang, Yin; Nikodem, Michal; Wysocki, Gerard

2013-01-01

A new detection method for Faraday rotation spectra of paramagnetic molecular species is presented. Near shot-noise limited performance in the mid-infrared is demonstrated using a heterodyne enhanced Faraday rotation spectroscopy (H-FRS) system without any cryogenic cooling. Theoretical analysis is performed to estimate the ultimate sensitivity to polarization rotation for both heterodyne and conventional FRS. Sensing of nitric oxide (NO) has been performed with an H-FRS system based on thermoelectrically cooled 5.24 μm quantum cascade laser (QCL) and a mercury-cadmium-telluride photodetector. The QCL relative intensity noise that dominates at low frequencies is largely avoided by performing the heterodyne detection in radio frequency range. H-FRS exhibits a total noise level of only 3.7 times the fundamental shot noise. The achieved sensitivity to polarization rotation of 1.8 × 10−8 rad/Hz1/2 is only 5.6 times higher than the ultimate theoretical sensitivity limit estimated for this system. The path- and bandwidth-normalized NO detection limit of 3.1 ppbv-m/Hz1/2 was achieved using the R(17/2) transition of NO at 1906.73 cm−1. PMID:23388967

Electrochemical Microsensors for the Detection of Cadmium(II) and Lead(II) Ions in Plants

PubMed Central

Krystofova, Olga; Trnkova, Libuse; Adam, Vojtech; Zehnalek, Josef; Hubalek, Jaromir; Babula, Petr; Kizek, Rene

2010-01-01

Routine determination of trace metals in complex media is still a difficult task for many analytical instruments. The aim of this work was to compare three electro-chemical instruments [a standard potentiostat (Autolab), a commercially available miniaturized potentiostat (PalmSens) and a homemade micropotentiostat] for easy-to-use and sensitive determination of cadmium(II) and lead(II) ions. The lowest detection limits (hundreds of pM) for both metals was achieved by using of the standard potentiostat, followed by the miniaturized potentiostat (tens of nM) and the homemade instrument (hundreds of nM). Nevertheless, all potentiostats were sensitive enough to evaluate contamination of the environment, because the environmental limits for both metals are higher than detection limits of the instruments. Further, we tested all used potentiostats and working electrodes on analysis of environmental samples (rainwater, flour and plant extract) with artificially added cadmium(II) and lead(II). Based on the similar results obtained for all potentiostats we choose a homemade instrument with a carbon tip working electrode for our subsequent environmental experiments, in which we analyzed maize and sunflower seedlings and rainwater obtained from various sites in the Czech Republic. PMID:22219663

Limits to the Fraction of High-energy Photon Emitting Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Akerlof, Carl W.; Zheng, WeiKang

2013-02-01

After almost four years of operation, the two instruments on board the Fermi Gamma-ray Space Telescope have shown that the number of gamma-ray bursts (GRBs) with high-energy photon emission above 100 MeV cannot exceed roughly 9% of the total number of all such events, at least at the present detection limits. In a recent paper, we found that GRBs with photons detected in the Large Area Telescope have a surprisingly broad distribution with respect to the observed event photon number. Extrapolation of our empirical fit to numbers of photons below our previous detection limit suggests that the overall rate of such low flux events could be estimated by standard image co-adding techniques. In this case, we have taken advantage of the excellent angular resolution of the Swift mission to provide accurate reference points for 79 GRB events which have eluded any previous correlations with high-energy photons. We find a small but significant signal in the co-added field. Guided by the extrapolated power-law fit previously obtained for the number distribution of GRBs with higher fluxes, the data suggest that only a small fraction of GRBs are sources of high-energy photons.

Detection of Salmonella invA gene in shrimp enrichment culture by polymerase chain reaction.

PubMed

Upadhyay, Bishnu Prasad; Utrarachkij, Fuangfa; Thongshoob, Jarinee; Mahakunkijcharoen, Yuvadee; Wongchinda, Niracha; Suthienkul, Orasa; Khusmith, Srisin

2010-03-01

Contamination of seafood with salmonellae is a major public health concern. Detection of Salmonella by standard culture methods is time consuming. In this study, an enrichment culture step prior to polymerase chain reaction (PCR) was applied to detect 284 bp fragment of Salmonella invA in comparison with the conventional culture method in 100 shrimp samples collected from four different shrimp farms and fresh food markets around Bangkok. Samples were pre-enriched in non-selective lactose broth (LB) and selective tetrathionate broth (TTB). PCR detection limit was 10 pg and 10(4) cfu/ml of viable salmonellae with 100% specificity. PCR assay detected 19 different Salmonella serovars belonging to 8 serogroups (B, C1, C2-C3, D1, E1, E4 and K) commonly found in clinical and environmental samples in Thailand. The detection rate of PCR following TTB enrichment (24%) was higher than conventional culture method (19%). PCR following TTB, but not in LB enrichment allowed salmonella detection with 84% sensitivity, 90% specificity and 89% accuracy. Shrimp samples collected from fresh food markets had higher levels of contaminated salmonellae than those from shrimp farms. The results indicated that incorporation of an enrichment step prior to PCR has the potential to be applied for detection of naturally contaminated salmonellae in food, environment and clinical samples.

The Bivariate Luminosity--HI Mass Distribution Function of Galaxies based on the NIBLES Survey

NASA Astrophysics Data System (ADS)

Butcher, Zhon; Schneider, Stephen E.; van Driel, Wim; Lehnert, Matt

2016-01-01

We use 21cm HI line observations for 2610 galaxies from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES) to derive a bivariate luminosity--HI mass distribution function. Our HI survey was selected to randomly probe the local (900 < cz < 12,000 km/s) galaxy population in each 0.5 mag wide bin for the absolute z-band magnitude range of -13.5 < Mz < -24 without regard to morphology or color. This targeted survey allowed more on-source integration time for weak and non-detected sources, enabling us to probe lower HI mass fractions and apply lower upper limits for non-detections than would be possible with the larger blind HI surveys. Additionally, we obtained a factor of four higher sensitivity follow-up observations at Arecibo of 90 galaxies from our non-detected and marginally detected categories to quantify the underlying HI distribution of sources not detected at Nançay. Using the optical luminosity function and our higher sensitivity follow up observations as priors, we use a 2D stepwise maximum likelihood technique to derive the two dimensional volume density distribution of luminosity and HI mass in each SDSS band.

Loop-mediated isothermal amplification (LAMP) assay for the rapid detection of the sexually-transmitted parasite, Trichomonas vaginalis.

PubMed

Adao, Davin Edric V; Rivera, Windell L

2016-01-01

A loop-mediated isothermal amplification (LAMP) assay was developed to detect the sexually-transmitted parasite, Trichomonas vaginalis in vaginal swabs. The presence of T. vaginalis was detected from 121 female sex workers attending a social hygiene clinic in Balibago, Angeles City, Pampanga, Philippines using culture, polymerase chain reaction (PCR), and the developed LAMP assay. The high analytical sensitivity of LAMP detected a higher prevalence of T. vaginalis (42.06%) compared to culture (8.26%) and PCR (7.44%). Additionally, this assay did not cross-react with DNAs of other trichomonads that can infect humans such as Trichomonas tenax and Pentatrichomonas hominis as well as the pathogens, Candida albicans and Staphylococcus aureus. The LAMP assay developed had a limit of detection (0.036 ng/μl) lower than that of PCR using the primers TvK3 and TvK7 (0.36 ng/μl). Prevalence of T. vaginalis in female sex workers in this area of the Philippines may be higher than previously estimated. Discordant results of PCR and LAMP may be due to different reactions to different kinds of inhibitors in the vaginal swabs.

Multi-Frequency Signal Detection Based on Frequency Exchange and Re-Scaling Stochastic Resonance and Its Application to Weak Fault Diagnosis

PubMed Central

Leng, Yonggang; Fan, Shengbo

2018-01-01

Mechanical fault diagnosis usually requires not only identification of the fault characteristic frequency, but also detection of its second and/or higher harmonics. However, it is difficult to detect a multi-frequency fault signal through the existing Stochastic Resonance (SR) methods, because the characteristic frequency of the fault signal as well as its second and higher harmonics frequencies tend to be large parameters. To solve the problem, this paper proposes a multi-frequency signal detection method based on Frequency Exchange and Re-scaling Stochastic Resonance (FERSR). In the method, frequency exchange is implemented using filtering technique and Single SideBand (SSB) modulation. This new method can overcome the limitation of "sampling ratio" which is the ratio of the sampling frequency to the frequency of target signal. It also ensures that the multi-frequency target signals can be processed to meet the small-parameter conditions. Simulation results demonstrate that the method shows good performance for detecting a multi-frequency signal with low sampling ratio. Two practical cases are employed to further validate the effectiveness and applicability of this method. PMID:29693577

Continuous flow nanoparticle concentration using alternating current-electroosmotic flow.

PubMed

Hoettges, Kai F; McDonnell, Martin B; Hughes, Michael P

2014-02-01

Achieving real-time detection of environmental pathogens such as viruses and bacterial spores requires detectors with both rapid action and a suitable detection threshold. However, most biosensors have detection limits of an order of magnitude or more above the potential infection threshold, limiting their usefulness. This can be improved through the use of automated sample preparation techniques such as preconcentration. In this paper, we describe the use of AC electroosmosis to concentrate nanoparticles from a continuous flow. Electrodes at an optimized angle across a flow cell, and energized by a 1 kHz signal, were used to push nanoparticles to one side of a flow cell, and to extract the resulting stream with a high particle concentration from that side of the flow cell. A simple model of the behavior of particles in the flow cell has been developed, which shows good agreement with experimental results. The method indicates potential for higher concentration factors through cascading devices. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The evens and odds of CMB anomalies

NASA Astrophysics Data System (ADS)

Gruppuso, A.; Kitazawa, N.; Lattanzi, M.; Mandolesi, N.; Natoli, P.; Sagnotti, A.

2018-06-01

The lack of power of large-angle CMB anisotropies is known to increase its statistical significance at higher Galactic latitudes, where a string-inspired pre-inflationary scale Δ can also be detected. Considering the Planck 2015 data, and relying largely on a Bayesian approach, we show that the effect is mostly driven by the even - ℓ harmonic multipoles with ℓ ≲ 20, which appear sizably suppressed in a way that is robust with respect to Galactic masking, along with the corresponding detections of Δ. On the other hand, the first odd - ℓ multipoles are only suppressed at high Galactic latitudes. We investigate this behavior in different sky masks, constraining Δ through even and odd multipoles, and we elaborate on possible implications. We include low- ℓ polarization data which, despite being noise-limited, help in attaining confidence levels of about 3 σ in the detection of Δ. We also show by direct forecasts that a future all-sky E-mode cosmic-variance-limited polarization survey may push the constraining power for Δ beyond 5 σ.

Refractive index sensor based on a polymer fiber directional coupler for low index sensing.

PubMed

Lee, Kwang Jo; Liu, Xiaoqi; Vuillemin, Nelly; Lwin, Richard; Leon-Saval, Sergio G; Argyros, Alexander; Kuhlmey, Boris T

2014-07-14

We propose, numerically analyze and experimentally demonstrate a novel refractive index sensor specialized for low index sensing. The device is based on a directional coupler architecture implemented in a single microstructured polymer optical fiber incorporating two waveguides within it: a single-mode core and a satellite waveguide consisting of a hollow high-index ring. This hollow channel is filled with fluid and the refractive index of the fluid is detected through changes to the wavelength at which resonant coupling occurs between the two waveguides. The sensor design was optimized for both higher sensitivity and lower detection limit, with simulations and experiments demonstrating a sensitivity exceeding 1.4 × 10(3) nm per refractive index unit. Simulations indicate a detection limit of ~2 × 10(-6) refractive index units is achievable. We also numerically investigate the performance for refractive index changes localized at the surface of the holes, a case of particular importance for biosensing.

Peptide Functionalized Gold Nanorods for the Sensitive Detection of a Cardiac Biomarker Using Plasmonic Paper Devices.

PubMed

Tadepalli, Sirimuvva; Kuang, Zhifeng; Jiang, Qisheng; Liu, Keng-Ku; Fisher, Marilee A; Morrissey, Jeremiah J; Kharasch, Evan D; Slocik, Joseph M; Naik, Rajesh R; Singamaneni, Srikanth

2015-11-10

The sensitivity of localized surface plasmon resonance (LSPR) of metal nanostructures to adsorbates lends itself to a powerful class of label-free biosensors. Optical properties of plasmonic nanostructures are dependent on the geometrical features and the local dielectric environment. The exponential decay of the sensitivity from the surface of the plasmonic nanotransducer calls for the careful consideration in its design with particular attention to the size of the recognition and analyte layers. In this study, we demonstrate that short peptides as biorecognition elements (BRE) compared to larger antibodies as target capture agents offer several advantages. Using a bioplasmonic paper device (BPD), we demonstrate the selective and sensitive detection of the cardiac biomarker troponin I (cTnI). The smaller sized peptide provides higher sensitivity and a lower detection limit using a BPD. Furthermore, the excellent shelf-life and thermal stability of peptide-based LSPR sensors, which precludes the need for special storage conditions, makes it ideal for use in resource-limited settings.

Quantile regression for the statistical analysis of immunological data with many non-detects.

PubMed

Eilers, Paul H C; Röder, Esther; Savelkoul, Huub F J; van Wijk, Roy Gerth

2012-07-07

Immunological parameters are hard to measure. A well-known problem is the occurrence of values below the detection limit, the non-detects. Non-detects are a nuisance, because classical statistical analyses, like ANOVA and regression, cannot be applied. The more advanced statistical techniques currently available for the analysis of datasets with non-detects can only be used if a small percentage of the data are non-detects. Quantile regression, a generalization of percentiles to regression models, models the median or higher percentiles and tolerates very high numbers of non-detects. We present a non-technical introduction and illustrate it with an implementation to real data from a clinical trial. We show that by using quantile regression, groups can be compared and that meaningful linear trends can be computed, even if more than half of the data consists of non-detects. Quantile regression is a valuable addition to the statistical methods that can be used for the analysis of immunological datasets with non-detects.

Detection limits of quantitative and digital PCR assays and their influence in presence-absence surveys of environmental DNA

USGS Publications Warehouse

Hunter, Margaret; Dorazio, Robert M.; Butterfield, John S.; Meigs-Friend, Gaia; Nico, Leo; Ferrante, Jason A.

2017-01-01

A set of universal guidelines is needed to determine the limit of detection (LOD) in PCR-based analyses of low concentration DNA. In particular, environmental DNA (eDNA) studies require sensitive and reliable methods to detect rare and cryptic species through shed genetic material in environmental samples. Current strategies for assessing detection limits of eDNA are either too stringent or subjective, possibly resulting in biased estimates of species’ presence. Here, a conservative LOD analysis grounded in analytical chemistry is proposed to correct for overestimated DNA concentrations predominantly caused by the concentration plateau, a nonlinear relationship between expected and measured DNA concentrations. We have used statistical criteria to establish formal mathematical models for both quantitative and droplet digital PCR. To assess the method, a new Grass Carp (Ctenopharyngodon idella) TaqMan assay was developed and tested on both PCR platforms using eDNA in water samples. The LOD adjustment reduced Grass Carp occupancy and detection estimates while increasing uncertainty – indicating that caution needs to be applied to eDNA data without LOD correction. Compared to quantitative PCR, digital PCR had higher occurrence estimates due to increased sensitivity and dilution of inhibitors at low concentrations. Without accurate LOD correction, species occurrence and detection probabilities based on eDNA estimates are prone to a source of bias that cannot be reduced by an increase in sample size or PCR replicates. Other applications also could benefit from a standardized LOD such as GMO food analysis, and forensic and clinical diagnostics.

40 CFR 141.23 - Inorganic chemical sampling and analytical requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Inorganic Contaminants Contaminant MCL (mg/l) Methodology Detection limit (mg/l) Antimony 0.006 Atomic... January 23, 2006. Unit then, the MCL is 0.05 mg/L. 7 The MDL reported for EPA method 200.9 (Atomic... higher. Using multiple depositions, EPA 200.9 is capable of obtaining MDL of 0.0001 mg/L. 8 Using...

Comparison of OH reactivity measurements in the atmospheric simulation chamber SAPHIR

NASA Astrophysics Data System (ADS)

Fuchs, Hendrik; Novelli, Anna; Rolletter, Michael; Hofzumahaus, Andreas; Pfannerstill, Eva Y.; Kessel, Stephan; Edtbauer, Achim; Williams, Jonathan; Michoud, Vincent; Dusanter, Sebastien; Locoge, Nadine; Zannoni, Nora; Gros, Valerie; Truong, Francois; Sarda-Esteve, Roland; Cryer, Danny R.; Brumby, Charlotte A.; Whalley, Lisa K.; Stone, Daniel; Seakins, Paul W.; Heard, Dwayne E.; Schoemaecker, Coralie; Blocquet, Marion; Coudert, Sebastien; Batut, Sebastien; Fittschen, Christa; Thames, Alexander B.; Brune, William H.; Ernest, Cheryl; Harder, Hartwig; Muller, Jennifer B. A.; Elste, Thomas; Kubistin, Dagmar; Andres, Stefanie; Bohn, Birger; Hohaus, Thorsten; Holland, Frank; Li, Xin; Rohrer, Franz; Kiendler-Scharr, Astrid; Tillmann, Ralf; Wegener, Robert; Yu, Zhujun; Zou, Qi; Wahner, Andreas

2017-10-01

Hydroxyl (OH) radical reactivity (kOH) has been measured for 18 years with different measurement techniques. In order to compare the performances of instruments deployed in the field, two campaigns were conducted performing experiments in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich in October 2015 and April 2016. Chemical conditions were chosen either to be representative of the atmosphere or to test potential limitations of instruments. All types of instruments that are currently used for atmospheric measurements were used in one of the two campaigns. The results of these campaigns demonstrate that OH reactivity can be accurately measured for a wide range of atmospherically relevant chemical conditions (e.g. water vapour, nitrogen oxides, various organic compounds) by all instruments. The precision of the measurements (limit of detection < 1 s-1 at a time resolution of 30 s to a few minutes) is higher for instruments directly detecting hydroxyl radicals, whereas the indirect comparative reactivity method (CRM) has a higher limit of detection of 2 s-1 at a time resolution of 10 to 15 min. The performances of the instruments were systematically tested by stepwise increasing, for example, the concentrations of carbon monoxide (CO), water vapour or nitric oxide (NO). In further experiments, mixtures of organic reactants were injected into the chamber to simulate urban and forested environments. Overall, the results show that the instruments are capable of measuring OH reactivity in the presence of CO, alkanes, alkenes and aromatic compounds. The transmission efficiency in Teflon inlet lines could have introduced systematic errors in measurements for low-volatile organic compounds in some instruments. CRM instruments exhibited a larger scatter in the data compared to the other instruments. The largest differences to reference measurements or to calculated reactivity were observed by CRM instruments in the presence of terpenes and oxygenated organic compounds (mixing ratio of OH reactants were up to 10 ppbv). In some of these experiments, only a small fraction of the reactivity is detected. The accuracy of CRM measurements is most likely limited by the corrections that need to be applied to account for known effects of, for example, deviations from pseudo first-order conditions, nitrogen oxides or water vapour on the measurement. Methods used to derive these corrections vary among the different CRM instruments. Measurements taken with a flow-tube instrument combined with the direct detection of OH by chemical ionisation mass spectrometry (CIMS) show limitations in cases of high reactivity and high NO concentrations but were accurate for low reactivity (< 15 s-1) and low NO (< 5 ppbv) conditions.

Glucose-oxidase label-based redox cycling for an incubation period-free electrochemical immunosensor.

PubMed

Singh, Amardeep; Park, Seonhwa; Yang, Haesik

2013-05-21

Catalytic reactions of enzyme labels in enzyme-linked immunosorbent assays require a long incubation period to obtain high signal amplification. We present herein a simple immunosensing scheme in which the incubation period is minimized without a large increase in the detection limit. This scheme is based on electrochemical-enzymatic (EN) redox cycling using glucose oxidase (GOx) as an enzyme label, Ru(NH3)6(3+) as a redox mediator, and glucose as an enzyme substrate. Fast electron mediation of Ru(NH3)6(3+) between the electrode and the GOx label attached to the electrode allows high signal amplification. The acquisition of chronocoulometric charges at a potential in the mass transfer-controlled region excludes the influence of the kinetics of Ru(NH3)6(2+) electrooxidation and also facilitates high signal-to-background ratios. The reaction between reduced GOx and Ru(NH3)6(3+) is rapid even in air-saturated Tris buffer, where the faster competitive reaction between reduced GOx and dissolved oxygen also occurs. The direct electrooxidation of glucose at the electrode and the direct electron transfer between glucose and Ru(NH3)6(3+) that undesirably increase background levels occur relatively slowly. The detection limit for the EN redox cycling-based detection of cancer antigen 125 (CA-125) in human serum is slightly higher than 0.1 U/mL for the incubation period of 0 min, and the detection limits for the incubation periods of 5 and 10 min are slightly lower than 0.1 U/mL, indicating that the detection limits are almost similar irrespective of the incubation period and that the immunosensor is highly sensitive.

Performance of blue-yellow screening test for antimicrobial detection in ovine milk.

PubMed

Linage, B; Gonzalo, C; Carriedo, J A; Asensio, J A; Blanco, M A; De La Fuente, L F; San Primitivo, F

2007-12-01

Drug residues in milk are important because of public health and industrial implications. The detection limits of 25 antimicrobial agents were determined by the blue-yellow screening method in ovine milk. For each drug, 8 concentrations were tested on 20 ovine milk samples from individual ewes in midlactation. Detection limits determined by means of logistic regression were below European Union maximum residue limits (EU-MRL) for penicillin G (3 to 4 microg/kg), ceftiofur (96 to 107 microg/kg), framycetin (720 to 781 microg/kg), neomycin (915 to 1,084 microg/kg), and tylosin (44 to 51 microg/kg). Detection limits for ampicillin (5 to 6 microg/kg), cloxacillin (33 to 42 microg/kg), cefoperazone (73 to 82 microg/kg), cefalexin (160 to 202 microg/kg), gentamycin (355 to 382 microg/kg), streptomycin (3,063 to 3,593 microg/kg), tilmicosin (109 to 131 microg/kg), erythromycin (444 to 522 microg/kg), spyramicin (1,106 to 1,346 microg/kg), sulfadimethoxine (101 to 119 microg/kg), sulfathiazole (122 to 151 microg/kg), sulfamethazine (309 to 328 microg/kg), sulfanilamide (1,750 to 2,674 microg/kg), tetracycline (233 to 257 microg/kg), oxytetracycline (398 to 501 microg/kg), doxycycline (323 to 419 microg/kg), chlortetracycline (3,331 to 3,989 microg/kg), danofloxacin (4.7 to 5.5 mg/kg), enrofloxacin (41 to 46 mg/kg), and flumequin (63 to 71 mg/kg) were higher than the EU-MRL. Although the blue-yellow method showed improved sensitivity compared with other tests studied in ovine milk, the performance of screening methods for detecting antimicrobial agents in milk of this species should be improved.

Comparison of OH Reactivity Instruments in the Atmosphere Simulation Chamber SAPHIR.

NASA Astrophysics Data System (ADS)

Fuchs, H.; Novelli, A.; Rolletter, M.; Hofzumahaus, A.; Pfannerstill, E.; Edtbauer, A.; Kessel, S.; Williams, J.; Michoud, V.; Dusanter, S.; Locoge, N.; Zannoni, N.; Gros, V.; Truong, F.; Sarda Esteve, R.; Cryer, D. R.; Brumby, C.; Whalley, L.; Stone, D. J.; Seakins, P. W.; Heard, D. E.; Schoemaecker, C.; Blocquet, M.; Fittschen, C. M.; Thames, A. B.; Coudert, S.; Brune, W. H.; Batut, S.; Tatum Ernest, C.; Harder, H.; Elste, T.; Bohn, B.; Hohaus, T.; Holland, F.; Muller, J. B. A.; Li, X.; Rohrer, F.; Kubistin, D.; Kiendler-Scharr, A.; Tillmann, R.; Andres, S.; Wegener, R.; Yu, Z.; Zou, Q.; Wahner, A.

2017-12-01

Two campaigns were conducted performing experiments in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich in October 2015 and April 2016 to compare hydroxyl (OH) radical reactivity (kOH) measurements. Chemical conditions were chosen either to be representative of the atmosphere or to test potential limitations of instruments. The results of these campaigns demonstrate that OH reactivity can be accurately measured for a wide range of atmospherically relevant chemical conditions (e.g. water vapor, nitrogen oxides, various organic compounds) by all instruments. The precision of the measurements is higher for instruments directly detecting hydroxyl radicals (OH), whereas the indirect Comparative Reactivity Method (CRM) has a higher limit of detection of 2s-1 at a time resolution of 10 to 15 min. The performances of the instruments were systematically tested by stepwise increasing, for example, the concentrations of carbon monoxide (CO), water vapor or nitric oxide (NO). In further experiments, mixtures of organic reactants were injected in the chamber to simulate urban and forested environments. Overall, the results show that instruments are capable of measuring OH reactivity in the presence of CO, alkanes, alkenes and aromatic compounds. The transmission efficiency in Teflon inlet lines could have introduced systematic errors in measurements for low-volatile organic compounds in some instruments. CRM instruments exhibited a larger scatter in the data compared to the other instruments. The largest differences to the reference were observed by CRM instruments in the presence of terpenes and oxygenated organic compounds. In some of these experiments, only a small fraction of the reactivity is detected. The accuracy of CRM measurements is most likely limited by the corrections that need to be applied in order to account for known effects of, for example, deviations from pseudo-first order conditions, nitrogen oxides or water vapor on the measurement. Methods to derive these corrections vary among the different CRM instruments. Measurements by a flow-tube instrument combined with the direct detection of OH by chemical ionization mass spectrometry (CIMS) show limitations, but were accurate for low reactivity (< 15s -1) and low NO (< 5 ppbv) conditions.

Rapid and Sensitive Detection of H7N9 Avian Influenza Virus by Use of Reverse Transcription–Loop-Mediated Isothermal Amplification

PubMed Central

Zhang, Jinhai; Feng, Youjun; Hu, Dan; Lv, Heng; Zhu, Jing; Cao, Min; Zheng, Feng; Zhu, Jin; Gong, Xiufang; Hao, Lina; Srinivas, Swaminath; Ren, Hao; Qi, Zhongtian

2013-01-01

An epidemic of human H7N9 influenza virus infection recently emerged in China whose clinical features include high mortality and which has also resulted in serious economic loss. The novel reassortant avian-origin influenza A (H7N9) virus which was the causative agent of this epidemic raised the possibility of triggering a large-scale influenza pandemic worldwide. It seemed likely that fast molecular detection assays specific for this virus would be in great demand. Here, we report a one-step reverse transcription–loop-mediated isothermal amplification (RT-LAMP) method for rapid detection of the hemagglutinin (HA) and neuraminidase (NA) genes of H7N9 virus, the minimum detection limit of which was evaluated using in vitro RNA transcription templates. In total, 135 samples from clinical specimens (from either patients or poultry) were tested using this method in comparison with the real-time PCR recommended by the World Health Organization (WHO). Our results showed that (i) RT-LAMP-based trials can be completed in approximately 12 to 23 min and (ii) the detection limit for the H7 gene is around 10 copies per reaction, similar to that of the real-time PCR, whereas the detection limit for its counterpart the N9 gene is 5 copies per reaction, a 100-fold-higher sensitivity than the WHO-recommended method. Indeed, this excellent performance of our method was also validated by the results for a series of clinical specimens. Therefore, we believe that the simple, fast, and sensitive method of RT-LAMP might be widely applied for detection of H7N9 infections and may play a role in prevention of an influenza pandemic. PMID:24006004

An Uncertainty-Based Distributed Fault Detection Mechanism for Wireless Sensor Networks

PubMed Central

Yang, Yang; Gao, Zhipeng; Zhou, Hang; Qiu, Xuesong

2014-01-01

Exchanging too many messages for fault detection will cause not only a degradation of the network quality of service, but also represents a huge burden on the limited energy of sensors. Therefore, we propose an uncertainty-based distributed fault detection through aided judgment of neighbors for wireless sensor networks. The algorithm considers the serious influence of sensing measurement loss and therefore uses Markov decision processes for filling in missing data. Most important of all, fault misjudgments caused by uncertainty conditions are the main drawbacks of traditional distributed fault detection mechanisms. We draw on the experience of evidence fusion rules based on information entropy theory and the degree of disagreement function to increase the accuracy of fault detection. Simulation results demonstrate our algorithm can effectively reduce communication energy overhead due to message exchanges and provide a higher detection accuracy ratio. PMID:24776937

Variation in the limit-of-detection of the ProSpecT Campylobacter microplate enzyme immunoassay in stools spiked with emerging Campylobacter species.

PubMed

Bojanić, Krunoslav; Midwinter, Anne Camilla; Marshall, Jonathan Craig; Rogers, Lynn Elizabeth; Biggs, Patrick Jon; Acke, Els

2016-08-01

Campylobacter enteritis in humans is primarily associated with C. jejuni/coli infection. The impact of other Campylobacter spp. is likely to be underestimated due to the bias of culture methods towards Campylobacter jejuni/coli diagnosis. Stool antigen tests are becoming increasingly popular and appear generally less species-specific. A review of independent studies of the ProSpecT® Campylobacter Microplate enzyme immunoassay (EIA) developed for C. jejuni/coli showed comparable diagnostic results to culture methods but the examination of non-jejuni/coli Campylobacter spp. was limited and the limit-of-detection (LOD), where reported, varied between studies. This study investigated LOD of EIA for Campylobacter upsaliensis, Campylobacter hyointestinalis and Campylobacter helveticus spiked in human stools. Multiple stools and Campylobacter isolates were used in three different concentrations (10(4)-10(9)CFU/ml) to reflect sample heterogeneity. All Campylobacter species evaluated were detectable by EIA. Multivariate analysis showed LOD varied between Campylobacter spp. and faecal consistency as fixed effects and individual faecal samples as random effects. EIA showed excellent performance in replicate testing for both within and between batches of reagents, in agreement between visual and spectrophotometric reading of results, and returned no discordance between the bacterial concentrations within independent dilution test runs (positive results with lower but not higher concentrations). This study shows how limitations in experimental procedures lead to an overestimation of consistency and uniformity of LOD for EIA that may not hold under routine use in diagnostic laboratories. Benefits and limitations for clinical practice and the influence on estimates of performance characteristics from detection of multiple Campylobacter spp. by EIA are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of Conventional PCR, Multiplex PCR, and Loop-Mediated Isothermal Amplification Assays for Rapid Detection of Arcobacter Species

PubMed Central

Wang, Xiaoyu; Seo, Dong Joo; Lee, Min Hwa

2014-01-01

This study aimed to develop a loop-mediated isothermal amplification (LAMP) method for the rapid detection of Arcobacter species. Specific primers targeting the 23S ribosomal RNA gene were used to detect Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii. The specificity of the LAMP primer set was assessed using DNA samples from a panel of Arcobacter and Campylobacter species, and the sensitivity was determined using serial dilutions of Arcobacter species cultures. LAMP showed a 10- to 1,000-fold-higher sensitivity than multiplex PCR, with a detection limit of 2 to 20 CFU per reaction in vitro. Whereas multiplex PCR showed cross-reactivity with Campylobacter species, the LAMP method developed in this study was more sensitive and reliable than conventional PCR or multiplex PCR for the detection of Arcobacter species. PMID:24478488

Detecting local diversity-dependence in diversification.

PubMed

Xu, Liang; Etienne, Rampal S

2018-04-06

Whether there are ecological limits to species diversification is a hotly debated topic. Molecular phylogenies show slowdowns in lineage accumulation, suggesting that speciation rates decline with increasing diversity. A maximum-likelihood (ML) method to detect diversity-dependent (DD) diversification from phylogenetic branching times exists, but it assumes that diversity-dependence is a global phenomenon and therefore ignores that the underlying species interactions are mostly local, and not all species in the phylogeny co-occur locally. Here, we explore whether this ML method based on the nonspatial diversity-dependence model can detect local diversity-dependence, by applying it to phylogenies, simulated with a spatial stochastic model of local DD speciation, extinction, and dispersal between two local communities. We find that type I errors (falsely detecting diversity-dependence) are low, and the power to detect diversity-dependence is high when dispersal rates are not too low. Interestingly, when dispersal is high the power to detect diversity-dependence is even higher than in the nonspatial model. Moreover, estimates of intrinsic speciation rate, extinction rate, and ecological limit strongly depend on dispersal rate. We conclude that the nonspatial DD approach can be used to detect diversity-dependence in clades of species that live in not too disconnected areas, but parameter estimates must be interpreted cautiously. © 2018 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

Advancing Peptide-Based Biorecognition Elements for Biosensors Using in-Silico Evolution.

PubMed

Xiao, Xingqing; Kuang, Zhifeng; Slocik, Joseph M; Tadepalli, Sirimuvva; Brothers, Michael; Kim, Steve; Mirau, Peter A; Butkus, Claire; Farmer, Barry L; Singamaneni, Srikanth; Hall, Carol K; Naik, Rajesh R

2018-05-25

Sensors for human health and performance monitoring require biological recognition elements (BREs) at device interfaces for the detection of key molecular biomarkers that are measurable biological state indicators. BREs, including peptides, antibodies, and nucleic acids, bind to biomarkers in the vicinity of the sensor surface to create a signal proportional to the biomarker concentration. The discovery of BREs with the required sensitivity and selectivity to bind biomarkers at low concentrations remains a fundamental challenge. In this study, we describe an in-silico approach to evolve higher sensitivity peptide-based BREs for the detection of cardiac event marker protein troponin I (cTnI) from a previously identified BRE as the parental affinity peptide. The P2 affinity peptide, evolved using our in-silico method, was found to have ∼16-fold higher affinity compared to the parent BRE and ∼10 fM (0.23 pg/mL) limit of detection. The approach described here can be applied towards designing BREs for other biomarkers for human health monitoring.

UV plasmonic device for sensing ethanol and acetone

NASA Astrophysics Data System (ADS)

Honda, Mitsuhiro; Ichikawa, Yo; Rozhin, Alex G.; Kulinich, Sergei A.

2018-01-01

In the present study, we demonstrate efficient detection of volatile organic vapors with improved sensitivity, exploiting the localized surface plasmon resonance of indium nanograins in the UV range (UV-LSPR). The sensitivity of deep-UV-LSPR measurements toward ethanol was observed to be 0.004 nm/ppm, which is 10 times higher than that of a previously reported visible-LSPR device based on Ag nanoprisms [Sensors 11, 8643 (2011)]. Although practical issues such as improving detection limits are still remaining, the results of the present study suggest that the new approach based on UV-LSPR may open new avenues to the detection of organic molecules in solid, liquid, and gas phases using plasmonic sensors.

The Phosphorylation State of the Drosophila TRP Channel Modulates the Frequency Response to Oscillating Light In Vivo

PubMed Central

Rhodes-Mordov, Elisheva; Katz, Ben; Oberegelsbacher, Claudia; Yasin, Bushra; Tzadok, Hanan; Huber, Armin

2017-01-01

Drosophila photoreceptors respond to oscillating light of high frequency (∼100 Hz), while the detected maximal frequency is modulated by the light rearing conditions, thus enabling high sensitivity to light and high temporal resolution. However, the molecular basis for this adaptive process is unclear. Here, we report that dephosphorylation of the light-activated transient receptor potential (TRP) ion channel at S936 is a fast, graded, light-dependent, and Ca2+-dependent process that is partially modulated by the rhodopsin phosphatase retinal degeneration C (RDGC). Electroretinogram measurements of the frequency response to oscillating lights in vivo revealed that dark-reared flies expressing wild-type TRP exhibited a detection limit of oscillating light at relatively low frequencies, which was shifted to higher frequencies upon light adaptation. Strikingly, preventing phosphorylation of the S936-TRP site by alanine substitution in transgenic Drosophila (trpS936A) abolished the difference in frequency response between dark-adapted and light-adapted flies, resulting in high-frequency response also in dark-adapted flies. In contrast, inserting a phosphomimetic mutation by substituting the S936-TRP site to aspartic acid (trpS936D) set the frequency response of light-adapted flies to low frequencies typical of dark-adapted flies. Light-adapted rdgC mutant flies showed relatively high S936-TRP phosphorylation levels and light–dark phosphorylation dynamics. These findings suggest that RDGC is one but not the only phosphatase involved in pS936-TRP dephosphorylation. Together, this study indicates that TRP channel dephosphorylation is a regulatory process that affects the detection limit of oscillating light according to the light rearing condition, thus adjusting dynamic processing of visual information under varying light conditions. SIGNIFICANCE STATEMENT Drosophila photoreceptors exhibit high temporal resolution as manifested in frequency response to oscillating light of high frequency (≤∼100 Hz). Light rearing conditions modulate the maximal frequency detected by photoreceptors, thus enabling them to maintain high sensitivity to light and high temporal resolution. However, the precise mechanisms for this process are not fully understood. Here, we show by combination of biochemistry and in vivo electrophysiology that transient receptor potential (TRP) channel dephosphorylation at a specific site is a fast, light-activated and Ca2+-dependent regulatory process. TRP dephosphorylation affects the detection limit of oscillating light according to the adaptation state of the photoreceptor cells by shifting the detection limit to higher frequencies upon light adaptation. This novel mechanism thus adjusts dynamic processing of visual information under varying light conditions. PMID:28314815

Analysis of RF emissions from laser induced breakdown of atmospheric air and metals

NASA Astrophysics Data System (ADS)

Paturi, Prem Kiran; Lakshmi, Vinoth Kumar; Elle, Manikanta; Chelikani, Leela

2013-10-01

The low frequency (RF, microwave) emissions from laser produced plasma (LPP) are of great interest because of their variety of applications. The RF waves emitted by the nanosecond LPP of atmospheric air and metal (Al, Cu) targets were detected using antennas over frequency ranges (30 MHz-18 GHz) and were monitored using a spectrum analyzer (3 Hz-50 GHz). With different target materials, the dominant emission lines were observed to fall in different specific frequency ranges within the detection limit. The emissions from Cu were in the higher frequency range (100-200 MHz) than that of Al (30-100 MHz) may be due to the higher electron density of Cu, which contributes to the LPP conductivity. From the LPP of atmospheric air, the RF output was found to be increasing with the input laser energy up to certain value, beyond which almost no emission was observed. This effect is attributed to the modification in the net induced dipole moment due to the multiple plasma sources in the LPP at higher input laser energies. The detected radiation was observed to be dependent on laser and antenna polarization. Further studies may lead to an efficient technique for material identification from the RF characteristic peaks.

Identifying and detecting facial expressions of emotion in peripheral vision.

PubMed

Smith, Fraser W; Rossit, Stephanie

2018-01-01

Facial expressions of emotion are signals of high biological value. Whilst recognition of facial expressions has been much studied in central vision, the ability to perceive these signals in peripheral vision has only seen limited research to date, despite the potential adaptive advantages of such perception. In the present experiment, we investigate facial expression recognition and detection performance for each of the basic emotions (plus neutral) at up to 30 degrees of eccentricity. We demonstrate, as expected, a decrease in recognition and detection performance with increasing eccentricity, with happiness and surprised being the best recognized expressions in peripheral vision. In detection however, while happiness and surprised are still well detected, fear is also a well detected expression. We show that fear is a better detected than recognized expression. Our results demonstrate that task constraints shape the perception of expression in peripheral vision and provide novel evidence that detection and recognition rely on partially separate underlying mechanisms, with the latter more dependent on the higher spatial frequency content of the face stimulus.

Identifying and detecting facial expressions of emotion in peripheral vision

PubMed Central

Rossit, Stephanie

2018-01-01

Facial expressions of emotion are signals of high biological value. Whilst recognition of facial expressions has been much studied in central vision, the ability to perceive these signals in peripheral vision has only seen limited research to date, despite the potential adaptive advantages of such perception. In the present experiment, we investigate facial expression recognition and detection performance for each of the basic emotions (plus neutral) at up to 30 degrees of eccentricity. We demonstrate, as expected, a decrease in recognition and detection performance with increasing eccentricity, with happiness and surprised being the best recognized expressions in peripheral vision. In detection however, while happiness and surprised are still well detected, fear is also a well detected expression. We show that fear is a better detected than recognized expression. Our results demonstrate that task constraints shape the perception of expression in peripheral vision and provide novel evidence that detection and recognition rely on partially separate underlying mechanisms, with the latter more dependent on the higher spatial frequency content of the face stimulus. PMID:29847562

Relationship Between Prebiopsy Multiparametric Magnetic Resonance Imaging (MRI), Biopsy Indication, and MRI-ultrasound Fusion-targeted Prostate Biopsy Outcomes.

PubMed

Meng, Xiaosong; Rosenkrantz, Andrew B; Mendhiratta, Neil; Fenstermaker, Michael; Huang, Richard; Wysock, James S; Bjurlin, Marc A; Marshall, Susan; Deng, Fang-Ming; Zhou, Ming; Melamed, Jonathan; Huang, William C; Lepor, Herbert; Taneja, Samir S

2016-03-01

Increasing evidence supports the use of magnetic resonance imaging (MRI)-ultrasound fusion-targeted prostate biopsy (MRF-TB) to improve the detection of clinically significant prostate cancer (PCa) while limiting detection of indolent disease compared to systematic 12-core biopsy (SB). To compare MRF-TB and SB results and investigate the relationship between biopsy outcomes and prebiopsy MRI. Retrospective analysis of a prospectively acquired cohort of men presenting for prostate biopsy over a 26-mo period. A total of 601 of 803 consecutively eligible men were included. All men were offered prebiopsy MRI and assigned a maximum MRI suspicion score (mSS). Men with an MRI abnormality underwent combined MRF-TB and SB. Detection rates for all PCa and high-grade PCa (Gleason score [GS] ≥7) were compared using the McNemar test. MRF-TB detected fewer GS 6 PCas (75 vs 121; p<0.001) and more GS ≥7 PCas (158 vs 117; p<0.001) than SB. Higher mSS was associated with higher detection of GS ≥7 PCa (p<0.001) but was not correlated with detection of GS 6 PCa. Prediction of GS ≥7 disease by mSS varied according to biopsy history. Compared to SB, MRF-TB identified more GS ≥7 PCas in men with no prior biopsy (88 vs 72; p=0.012), in men with a prior negative biopsy (28 vs 16; p=0.010), and in men with a prior cancer diagnosis (42 vs 29; p=0.043). MRF-TB detected fewer GS 6 PCas in men with no prior biopsy (32 vs 60; p<0.001) and men with prior cancer (30 vs 46; p=0.034). Limitations include the retrospective design and the potential for selection bias given a referral population. MRF-TB detects more high-grade PCas than SB while limiting detection of GS 6 PCa in men presenting for prostate biopsy. These findings suggest that prebiopsy multiparametric MRI and MRF-TB should be considered for all men undergoing prostate biopsy. In addition, mSS in conjunction with biopsy indications may ultimately help in identifying men at low risk of high-grade cancer for whom prostate biopsy may not be warranted. We examined how magnetic resonance imaging (MRI)-targeted prostate biopsy compares to traditional systematic biopsy in detecting prostate cancer among men with suspicion of prostate cancer. We found that MRI-targeted biopsy detected more high-grade cancers than systematic biopsy, and that MRI performed before biopsy can predict the risk of high-grade cancer. Copyright © 2015 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Online detection and quantification of ergot bodies in cereals using near infrared hyperspectral imaging.

PubMed

Vermeulen, Ph; Pierna, J A Fernández; Egmond, H P van; Dardenne, P; Baeten, V

2012-01-01

The occurrence of ergot bodies (sclerotia of Claviceps purpurea) in cereals presents a high toxicity risk for animals and humans due to the alkaloid content. To reduce this risk, the European Commission fixed an ergot concentration limit of 0.1% in all feedstuffs containing unground cereals, and a limit of 0.05% in 'intervention' cereals destined for humans. This study sought to develop a procedure based on near infrared hyperspectral imaging and multivariate image analysis to detect and quantify ergot contamination in cereals. Hyperspectral images were collected using an NIR hyperspectral line scan combined with a conveyor belt. All images consisted of lines of 320 pixels that were acquired at 209 wavelength channels (1100-2400 nm). To test the procedure, several wheat samples with different levels of ergot contamination were prepared. The results showed a correlation higher than 0.99 between the predicted values obtained using chemometric tools such as partial least squares discriminant analysis or support vector machine and the reference values. For a wheat sample with a level of ergot contamination as low as 0.01 %, it was possible to identify groups of pixels detected as ergot to conclude that the sample was contaminated. In addition, no false positives were obtained with non-contaminated samples. The limit of detection was found to be 145 mg/kg and the limit of quantification 341 mg/kg. The reproducibility tests of the measurements performed over several weeks showed that the results were always within the limits allowed. Additional studies were done to optimise the parameters in terms of number of samples analysed per unit of time or conveyor belt speed. It was shown that ergot can be detected using a speed of 1-100 mm/s and that a sample of 250 g can be analysed in 1 min.

Project AMIGA: A Minimal Covering Factor for Optically Thick Circumgalactic Gas around the Andromeda Galaxy

NASA Astrophysics Data System (ADS)

Howk, J. Christopher; Wotta, Christopher B.; Berg, Michelle A.; Lehner, Nicolas; Lockman, Felix J.; Hafen, Zachary; Pisano, D. J.; Faucher-Giguère, Claude-André; Wakker, Bart P.; Prochaska, J. Xavier; Wolfe, Spencer A.; Ribaudo, Joseph; Barger, Kathleen A.; Corlies, Lauren; Fox, Andrew J.; Guhathakurta, Puragra; Jenkins, Edward B.; Kalirai, Jason; O'Meara, John M.; Peeples, Molly S.; Stewart, Kyle R.; Strader, Jay

2017-09-01

We present a deep search for {{H}} {{I}} 21 cm emission from the gaseous halo of Messier 31 as part of Project AMIGA, a large Hubble Space Telescope program to study the circumgalactic medium of the Andromeda galaxy. Our observations with the Robert C. Byrd Green Bank Telescope target sight lines to 48 background AGNs, more than half of which have been observed in the ultraviolet with the Cosmic Origins Spectrograph, with impact parameters 25≲ ρ ≲ 340 {kpc} (0.1≲ ρ /{R}{vir}≲ 1.1). We do not detect any 21 cm emission toward these AGNs to limits of N({{H}} {{I}})≈ 4× {10}17 cm-2 (5σ ; per 2 kpc-diameter beam). This column density corresponds to an optical depth of ˜2.5 at the Lyman limit; thus, our observations overlap with absorption line studies of Lyman limit systems at higher redshift. Our non-detections place a limit on the covering factor of such optically thick gas around M31 to {f}c< 0.051 (at 90% confidence) for ρ ≤slant {R}{vir}. Although individual clouds have previously been found in the region between M31 and M33, the covering factor of strongly optically thick gas is quite small. Our upper limits on the covering factor are consistent with expectations from recent cosmological “zoom” simulations. Recent COS-Halos ultraviolet measurements of {{H}} {{I}} absorption about an ensemble of galaxies at z≈ 0.2 show significantly higher covering factors within ρ ≲ 0.5{R}{vir} at the same N({{H}} {{I}}), although the metal ion-to-{{H}} {{I}} ratios appear to be consistent with those seen in M31.

Doxycycline depletion and residues in eggs after oral administration to laying hens.

PubMed

Gajda, Anna; Posyniak, Andrzej

2015-01-01

The depletion of doxycycline (DC) residues in eggs was determined after oral drug administration by drinking water to laying hens. The antibiotic was supplied to birds for 5 consecutive days and the eggs were collected during medication and 18 days after withdrawal. DC residues were determined by LC-MS/MS. DC was isolated from eggs with a solution of 0.02 M of oxalic acid (pH 4), 0.1 M Na2EDTA and acetonitrile. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 2 and 5 µg kg(-1), respectively. Analyses were performed on whole egg, egg white and yolk separately. DC was detectable 24 h after the beginning of administration. The concentration of antibiotic increased daily, resulting in the highest DC concentration in whole eggs at the first day of the withdrawal period. Thirteen days after withdrawal, the content of DC in whole eggs was below the LOQ of the method. However, some differences were found in the depletion curve of DC between egg white and yolk. Residues of DC in egg white were much higher during treatment and 1 day after withdrawal, but later the concentration in egg white decreased fairly rapidly and a higher DC content in egg yolk was observed. The depletion period was shorter for egg white than for yolk, and DC was detected in the egg white until 12 days after withdrawal and 2 days more in egg yolk than in white. DC reached a peak faster in egg white, but the residues were detectable for longer period in the yolk.

Oligorecurrent prostate cancer limited to lymph nodes: getting our ducks in a row

PubMed

Fodor, Andrei; Lancia, Andrea; Ceci, Francesco; Picchio, Maria; Hoyer, Morten; Jereczek-Fossa, Barbara Alicja; Ost, Piet; Castellucci, Paolo; Incerti, Elena; Di Muzio, Nadia; Ingrosso, Gianluca

2018-05-11

Oligorecurrent prostate cancer with exclusive nodal involvement represents a common state of disease, amenable to local therapy. New radio-labeled tracers have enriched the possibility of cancer detection and treatment. In this review, we aim to illustrate the main nuclear medicine diagnostic options and the role of radiotherapy in this setting of patients. We performed a PubMed search referring to the PRISMA guidelines to analyze the performance of PSMA- and choline-PET in detecting oligorecurrence limited to lymph nodes, and to review the main studies supporting either ablative stereotactic body radiotherapy or regional lymph node irradiation in this clinical setting. PSMA-PET has shown higher efficacy in the diagnosis of nodal lesions if compared with choline-PET. More specifically, for PSA ≤ 2 ng/ml, the median detection rate of choline-PET ranges from 19.5 to 44.5%, whereas PSMA ranges from 51.5 to 74%. SBRT achieves high local control rates positively affecting progression-free survival (PFS), with androgen deprivation therapy (ADT)-free survival ranging from 25 to 44 months and with low toxicity rates (0-15%). Prophylactic nodal irradiation shows 3-year PFS rates ranging from 62 to 75%, but with a potential higher risk of toxicity. However, the chosen treatment option needs to be tailored on the single patient. Newer PET/CT radio-labeled tracers have increased disease detection in oligorecurrent prostate cancer patients. Growing evidence of their impact on metastasis-directed therapy encourages the use of the most advanced radiotherapy techniques in the clinical management of such patients.

Design of differential optical absorption spectroscopy long-path telescopes based on fiber optics.

PubMed

Merten, André; Tschritter, Jens; Platt, Ulrich

2011-02-10

We present a new design principle of telescopes for use in the spectral investigation of the atmosphere and the detection of atmospheric trace gases with the long-path differential optical absorption spectroscopy (DOAS) technique. A combination of emitting and receiving fibers in a single bundle replaces the commonly used coaxial-Newton-type combination of receiving and transmitting telescope. This very simplified setup offers a higher light throughput and simpler adjustment and allows smaller instruments, which are easier to handle and more portable. The higher transmittance was verified by ray-tracing calculations, which result in a theoretical factor threefold improvement in signal intensity compared with the old setup. In practice, due to the easier alignment and higher stability, up to factor of 10 higher signal intensities were found. In addition, the use of a fiber optic light source provides a better spectral characterization of the light source, which results in a lower detection limit for trace gases studied with this instrument. This new design will greatly enhance the usability and the range of applications of active DOAS instruments.

Halo independent comparison of direct dark matter detection data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gondolo, Paolo; Gelmini, Graciela B., E-mail: paolo@physics.utah.edu, E-mail: gelmini@physics.ucla.edu

We extend the halo-independent method of Fox, Liu, and Weiner to include energy resolution and efficiency with arbitrary energy dependence, making it more suitable for experiments to use in presenting their results. Then we compare measurements and upper limits on the direct detection of low mass ( ∼ 10 GeV) weakly interacting massive particles with spin-independent interactions, including the upper limit on the annual modulation amplitude from the CDMS collaboration. We find that isospin-symmetric couplings are severely constrained both by XENON100 and CDMS bounds, and that isospin-violating couplings are still possible at the lowest energies, while the tension of themore » higher energy CoGeNT bins with the CDMS modulation constraint remains. We find the CRESST-II signal is not compatible with the modulation signals of DAMA and CoGeNT.« less

Ultrafast electron microscopy integrated with a direct electron detection camera.

PubMed

Lee, Young Min; Kim, Young Jae; Kim, Ye-Jin; Kwon, Oh-Hoon

2017-07-01

In the past decade, we have witnessed the rapid growth of the field of ultrafast electron microscopy (UEM), which provides intuitive means to watch atomic and molecular motions of matter. Yet, because of the limited current of the pulsed electron beam resulting from space-charge effects, observations have been mainly made to periodic motions of the crystalline structure of hundreds of nanometers or higher by stroboscopic imaging at high repetition rates. Here, we develop an advanced UEM with robust capabilities for circumventing the present limitations by integrating a direct electron detection camera for the first time which allows for imaging at low repetition rates. This approach is expected to promote UEM to a more powerful platform to visualize molecular and collective motions and dissect fundamental physical, chemical, and materials phenomena in space and time.

Performance of a Borehole X-ray Fluorescence Spectrometer for Planetary Exploration

NASA Technical Reports Server (NTRS)

Kelliher, Warren C.; Carlberg, Ingrid A.; Elam, W. T.; Willard-Schmoe, Ella

2008-01-01

We have designed and constructed a borehole X-ray Fluorescence Spectrometer (XRFS) as part of the Mars Subsurface Access program [1]. It can be used to determine the composition of the Mars regolith at various depths by insertion into a pre-drilled borehole. The primary requirements and performance metrics for the instrument are to obtain parts-per-million (ppm) lower limits of detection over a wide range of elements in the periodic table (Magnesium to Lead). Power consumption during data collection was also measured. The prototype instrument is complete and preliminary testing has been performed. Terrestrial soil Standard Reference Materials were used as the test samples. Detection limits were about 10 weight ppm for most elements, with light elements being higher, up to 1.4 weight percent for magnesium. Power consumption (excluding ground support components) was 12 watts.

Double-Paddle Oscillators as Probes of Quantum Turbulence in the Zero Temperature Limit

NASA Astrophysics Data System (ADS)

Schmoranzer, David; Jackson, Martin; Zemma, Elisa; Luzuriaga, Javier

2017-06-01

We present a technical report on our tests of a double-paddle oscillator as a detector of quantum turbulence in superfluid 4He at low temperatures ranging from 20 to 1100 mK. The device, known to operate well in the two-fluid regime (Zemma and Luzuriaga in J Low Temp Phys 166:171-181, 2012), is also capable of detecting quantum turbulence in the zero temperature limit. The oscillator demonstrated Lorentzian responses with quality factors of order 10^5 in vacuum, and displayed negative-Duffing resonances in liquid, even at moderate drives. In superfluid He-II at low temperatures, its sensitivity was adversely affected by acoustic damping at higher harmonics. While it successfully created and detected the quantum turbulence, its overall performance does not compare favourably with other oscillators such as tuning forks.

Graphene-based electrochemical sensor for detection of 2,4,6-trinitrotoluene (TNT) in seawater: the comparison of single-, few-, and multilayer graphene nanoribbons and graphite microparticles.

PubMed

Goh, Madeline Shuhua; Pumera, Martin

2011-01-01

The detection of explosives in seawater is of great interest. We compared response single-, few-, and multilayer graphene nanoribbons and graphite microparticle-based electrodes toward the electrochemical reduction of 2,4,6-trinitrotoluene (TNT). We optimized parameters such as accumulation time, accumulation potential, and pH. We found that few-layer graphene exhibits about 20% enhanced signal for TNT after accumulation when compared to multilayer graphene nanoribbons. However, graphite microparticle-modified electrode provides higher sensitivity, and there was no significant difference in the performance of single-, few-, and multilayer graphene nanoribbons and graphite microparticles for the electrochemical detection of TNT. We established the limit of detection of TNT in untreated seawater at 1 μg/mL.

A fully battery-powered inexpensive spectrophotometric system for high-sensitivity point-of-care analysis on a microfluidic chip

PubMed Central

Dou, Maowei; Lopez, Juan; Rios, Misael; Garcia, Oscar; Xiao, Chuan; Eastman, Michael

2016-01-01

A cost-effective battery-powered spectrophotometric system (BASS) was developed for quantitative point-of-care (POC) analysis on a microfluidic chip. By using methylene blue as a model analyte, we first compared the performance of the BASS with a commercial spectrophotometric system, and further applied the BASS for loop-mediated isothermal amplification (LAMP) detection and subsequent quantitative nucleic acid analysis which exhibited a comparable limit of detection to that of Nanodrop. Compared to the commercial spectrophotometric system, our spectrophotometric system is lower-cost, consumes less reagents, and has a higher detection sensitivity. Most importantly, it does not rely on external power supplies. All these features make our spectrophotometric system highly suitable for a variety of POC analyses, such as field detection. PMID:27143408

Gravitational wave detection using laser interferometry beyond the standard quantum limit

NASA Astrophysics Data System (ADS)

Heurs, M.

2018-05-01

Interferometric gravitational wave detectors (such as advanced LIGO) employ high-power solid-state lasers to maximize their detection sensitivity and hence their reach into the universe. These sophisticated light sources are ultra-stabilized with regard to output power, emission frequency and beam geometry; this is crucial to obtain low detector noise. However, even when all laser noise is reduced as far as technically possible, unavoidable quantum noise of the laser still remains. This is a consequence of the Heisenberg Uncertainty Principle, the basis of quantum mechanics: in this case, it is fundamentally impossible to simultaneously reduce both the phase noise and the amplitude noise of a laser to arbitrarily low levels. This fact manifests in the detector noise budget as two distinct noise sources-photon shot noise and quantum radiation pressure noise-which together form a lower boundary for current-day gravitational wave detector sensitivities, the standard quantum limit of interferometry. To overcome this limit, various techniques are being proposed, among them different uses of non-classical light and alternative interferometer topologies. This article explains how quantum noise enters and manifests in an interferometric gravitational wave detector, and gives an overview of some of the schemes proposed to overcome this seemingly fundamental limitation, all aimed at the goal of higher gravitational wave event detection rates. This article is part of a discussion meeting issue `The promises of gravitational-wave astronomy'.

Gravitational wave detection using laser interferometry beyond the standard quantum limit.

PubMed

Heurs, M

2018-05-28

Interferometric gravitational wave detectors (such as advanced LIGO) employ high-power solid-state lasers to maximize their detection sensitivity and hence their reach into the universe. These sophisticated light sources are ultra-stabilized with regard to output power, emission frequency and beam geometry; this is crucial to obtain low detector noise. However, even when all laser noise is reduced as far as technically possible, unavoidable quantum noise of the laser still remains. This is a consequence of the Heisenberg Uncertainty Principle, the basis of quantum mechanics: in this case, it is fundamentally impossible to simultaneously reduce both the phase noise and the amplitude noise of a laser to arbitrarily low levels. This fact manifests in the detector noise budget as two distinct noise sources-photon shot noise and quantum radiation pressure noise-which together form a lower boundary for current-day gravitational wave detector sensitivities, the standard quantum limit of interferometry. To overcome this limit, various techniques are being proposed, among them different uses of non-classical light and alternative interferometer topologies. This article explains how quantum noise enters and manifests in an interferometric gravitational wave detector, and gives an overview of some of the schemes proposed to overcome this seemingly fundamental limitation, all aimed at the goal of higher gravitational wave event detection rates.This article is part of a discussion meeting issue 'The promises of gravitational-wave astronomy'. © 2018 The Author(s).

Microbial mineralization of dichloroethene and vinyl chloride under hypoxic conditions

USGS Publications Warehouse

Bradley, Paul M.; Chapelle, Francis H.

2011-01-01

Mineralization of 14C-radiolabled vinyl chloride ([1,2-14C] VC) and cis-dichloroethene ([1,2-14C] cis-DCE) under hypoxic (initial dissolved oxygen (DO) concentrations about 0.1 mg/L) and nominally anoxic (DO minimum detection limit = 0.01 mg/L) was examined in chloroethene-exposed sediments from two groundwater and two surface water sites. The results show significant VC and dichloroethene (DCE) mineralization under hypoxic conditions. All the sample treatments exhibited pseudo-first-order kinetics for DCE and VC mineralization over an extended range of substrate concentrations. First-order rates for VC mineralization were approximately 1 to 2 orders of magnitude higher in hypoxic groundwater sediment treatments and at least three times higher in hypoxic surface water sediment treatments than in the respective anoxic treatments. For VC, oxygen-linked processes accounted for 65 to 85% of mineralization at DO concentrations below 0.1 mg/L, and 14CO2 was the only degradation product observed in VC treatments under hypoxic conditions. Because the lower detection limit for DO concentrations measured in the field is typically 0.1 to 0.5 mg/L, these results indicate that oxygen-linked VC and DCE biodegradation can be significant under field conditions that appear anoxic. Furthermore, because rates of VC mineralization exceeded rates of DCE mineralization under hypoxic conditions, DCE accumulation without concomitant accumulation of VC may not be evidence of a DCE degradative “stall” in chloroethene plumes. Significantly, mineralization of VC above the level that could reasonably be attributed to residual DO contamination was also observed in several nominally anoxic (DO minimum detection limit = 0.01 mg/L) microcosm treatments.

Quantification of Protozoa and Viruses from Small Water Volumes

PubMed Central

Bonilla, J. Alfredo; Bonilla, Tonya D.; Abdelzaher, Amir M.; Scott, Troy M.; Lukasik, Jerzy; Solo-Gabriele, Helena M.; Palmer, Carol J.

2015-01-01

Large sample volumes are traditionally required for the analysis of waterborne pathogens. The need for large volumes greatly limits the number of samples that can be processed. The goals of this study were to compare extraction and detection procedures for quantifying protozoan parasites and viruses from small volumes of marine water. The intent was to evaluate a logistically simpler method of sample collection and processing that would facilitate direct pathogen measures as part of routine monitoring programs. Samples were collected simultaneously using a bilayer device with protozoa capture by size (top filter) and viruses capture by charge (bottom filter). Protozoan detection technologies utilized for recovery of Cryptosporidium spp. and Giardia spp. were qPCR and the more traditional immunomagnetic separation—IFA-microscopy, while virus (poliovirus) detection was based upon qPCR versus plaque assay. Filters were eluted using reagents consistent with the downstream detection technologies. Results showed higher mean recoveries using traditional detection methods over qPCR for Cryptosporidium (91% vs. 45%) and poliovirus (67% vs. 55%) whereas for Giardia the qPCR-based methods were characterized by higher mean recoveries (41% vs. 28%). Overall mean recoveries are considered high for all detection technologies. Results suggest that simultaneous filtration may be suitable for isolating different classes of pathogens from small marine water volumes. More research is needed to evaluate the suitability of this method for detecting pathogens at low ambient concentration levels. PMID:26114244

Quantification of Protozoa and Viruses from Small Water Volumes.

PubMed

Bonilla, J Alfredo; Bonilla, Tonya D; Abdelzaher, Amir M; Scott, Troy M; Lukasik, Jerzy; Solo-Gabriele, Helena M; Palmer, Carol J

2015-06-24

Large sample volumes are traditionally required for the analysis of waterborne pathogens. The need for large volumes greatly limits the number of samples that can be processed. The aims of this study were to compare extraction and detection procedures for quantifying protozoan parasites and viruses from small volumes of marine water. The intent was to evaluate a logistically simpler method of sample collection and processing that would facilitate direct pathogen measures as part of routine monitoring programs. Samples were collected simultaneously using a bilayer device with protozoa capture by size (top filter) and viruses capture by charge (bottom filter). Protozoan detection technologies utilized for recovery of Cryptosporidium spp. and Giardia spp. were qPCR and the more traditional immunomagnetic separation-IFA-microscopy, while virus (poliovirus) detection was based upon qPCR versus plaque assay. Filters were eluted using reagents consistent with the downstream detection technologies. Results showed higher mean recoveries using traditional detection methods over qPCR for Cryptosporidium (91% vs. 45%) and poliovirus (67% vs. 55%) whereas for Giardia the qPCR-based methods were characterized by higher mean recoveries (41% vs. 28%). Overall mean recoveries are considered high for all detection technologies. Results suggest that simultaneous filtration may be suitable for isolating different classes of pathogens from small marine water volumes. More research is needed to evaluate the suitability of this method for detecting pathogens at low ambient concentration levels.

Effects of Surface Albedo on Smoke Detection Through Geostationary Satellite Imagery in the Hazard Mapping System (HMS)

NASA Astrophysics Data System (ADS)

Salemi, A.; Ruminski, M. G.

2012-12-01

The Satellite Analysis Branch (SAB) of NOAA/NESDIS uses geostationary and polar orbiting satellite imagery to identify fires and smoke throughout the continental United States. The fires and smoke are analyzed daily on the Hazard Mapping System (HMS) and made available via the internet in various formats. Analysis of smoke plumes generated from wildfires, agricultural and prescribe burns is performed with single channel visible imagery primarily from NOAA's Geostationary Operational Environmental Satellite (GOES) animations. Identification of smoke in visible imagery is complicated by the presence of clouds, the viewing angle produced by the sun, smoke, satellite geometry, and the surface albedo of the ground below the smoke among other factors. This study investigates the role of surface albedo in smoke detection. LIght Detection And Ranging (LIDAR) instruments are capable of detecting smoke and other aerosols. Through the use of ground and space based LIDAR systems in areas of varying albedo a relationship between the subjective analyst drawn smoke plumes versus those detected by LIDAR is established. The ability to detect smoke over regions of higher albedo (brighter surface, such as grassland, scrub and desert) is diminished compared to regions of lower albedo (darker surface, such as forest and water). Users of the HMS smoke product need to be aware of this limitation in smoke detection in areas of higher albedo.

Comparative elemental analysis of fine particulate matter (PM2.5) from industrial and residential areas in Greater Cairo-Egypt by means of a multi-secondary target energy dispersive X-ray fluorescence spectrometer

NASA Astrophysics Data System (ADS)

Shaltout, Abdallah A.; Hassan, Salwa K.; Karydas, Andreas G.; Zaki, Z. I.; Mostafa, Nasser Y.; Kregsamer, Peter; Wobrauschek, Peter; Streli, Christina

2018-07-01

Fine aerosol particles with aerodynamic diameter equal or <2.5 μm (PM2.5) have been collected from industrial and residential areas of Greater Cairo, Egypt during two different seasons namely; autumn 2014 and winter 2014/2015. Energy dispersive X-ray fluorescence (EDXRF) analysis utilizing polarization geometry and three different secondary targets (CaF2, Ge, and Mo) was employed for the quantitative analysis of eighteen (18) elements in PM2.5 samples. Light elements like Na and Mg was possible to be quantified, whereas detection limits in the range of few ng m-3 were attained for the most of the detected elements. Although, the average mass concentrations of the PM2.5 collected from the residential area (27 ± 7 μg m-3) is close to the annual mean limit value, a significant number of the collected samples (33%) presented higher average mass concentrations. For the industrial location, the average mass concentration is equal to 55 ± 19 μg m-3, exceeded twofold the annual mean limit value of the European Commission. Remarkably high elemental concentrations were determined for the most of the detected elements from the industrial area samples, clearly indicating the significant influence of anthropogenic activities. The present optimized EDXRF analysis offered significantly improved analytical range and limits of detection with respect to previous similar studies, thus enhancing our knowledge and understanding on the contribution of different pollution sources.

Evaluation of a microbiological indicator test for antibiotic detection in ewe and goat milk.

PubMed

Comunian, R; Paba, A; Dupré, I; Daga, E S; Scintu, M F

2010-12-01

Antibiotics are widely used for therapeutic and prophylactic purposes in dairy animals. The presence of residual antibiotics in milk could cause potentially serious problems in human health and have technological implication in the manufacturing of dairy products. The aim of this study was to evaluate Delvotest Accelerator (DSM Food Specialties, Delft, the Netherlands), a new system for a fully automated microbial test to detect antibiotic residues in ewe and goat milk. Forty-three samples of raw, whole, refrigerated bulk-tank milk samples (22 of ewe milk and 21 of goat milk) were analyzed during the whole lactation period. Four concentrations of 4 antibiotics were diluted in milk: penicillin G at 1, 2, 3, and 4 μg/L; sulfadiazine at 25, 50, 100, and 200 μg/L; tetracycline at 50, 100, 200, and 400 μg/L; and gentamicin at 25, 50, 100, and 200 μg/L. The detection limit of the Delvotest Accelerator was calculated as the range of antibiotic concentrations within which 95% of positive result lie. The range of detection limit of penicillin G and sulfadiazine was easily detected by Delvotest Accelerator at or below the European Union maximum residue limits, both for ewe and goat milk samples. In contrast, the system showed a lower ability to detect tetracycline and gentamicin both for ewe and goat milk samples. Very low percentages of false-positive outcomes were obtained. Lactation phase did not seem to be a crucial factor affecting the ability of the Delvotest Accelerator to detect spiked milk samples. A higher detection ability was observed for goat milk samples compared with ewe milk samples. A negative correlation between the percentage of positive milk samples detected and milk fat, protein, and lactose contents was observed for gentamicin only. Copyright © 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The influence of spatial resolution and smoothing on the detectability of resting-state and task fMRI.

PubMed

Molloy, Erin K; Meyerand, Mary E; Birn, Rasmus M

2014-02-01

Functional MRI blood oxygen level-dependent (BOLD) signal changes can be subtle, motivating the use of imaging parameters and processing strategies that maximize the temporal signal-to-noise ratio (tSNR) and thus the detection power of neuronal activity-induced fluctuations. Previous studies have shown that acquiring data at higher spatial resolutions results in greater percent BOLD signal changes, and furthermore that spatially smoothing higher resolution fMRI data improves tSNR beyond that of data originally acquired at a lower resolution. However, higher resolution images come at the cost of increased acquisition time, and the number of image volumes also influences detectability. The goal of our study is to determine how the detection power of neuronally induced BOLD fluctuations acquired at higher spatial resolutions and then spatially smoothed compares to data acquired at the lower resolutions with the same imaging duration. The number of time points acquired during a given amount of imaging time is a practical consideration given the limited ability of certain populations to lie still in the MRI scanner. We compare acquisitions at three different in-plane spatial resolutions (3.50×3.50mm(2), 2.33×2.33mm(2), 1.75×1.75mm(2)) in terms of their tSNR, contrast-to-noise ratio, and the power to detect both task-related activation and resting-state functional connectivity. The impact of SENSE acceleration, which speeds up acquisition time increasing the number of images collected, is also evaluated. Our results show that after spatially smoothing the data to the same intrinsic resolution, lower resolution acquisitions have a slightly higher detection power of task-activation in some, but not all, brain areas. There were no significant differences in functional connectivity as a function of resolution after smoothing. Similarly, the reduced tSNR of fMRI data acquired with a SENSE factor of 2 is offset by the greater number of images acquired, resulting in few significant differences in detection power of either functional activation or connectivity after spatial smoothing. © 2013.

Optimization and characterization of condensation nucleation light scattering detection coupled with supercritical fluid chromatography

NASA Astrophysics Data System (ADS)

Yang, Shaoping

This dissertation is an investigation of two aspects of coupling condensation nucleation light scattering detection (CNLSD) with supercritical fluid chromatography (SFC). In the first part, it was demonstrated that CNLSD was compatible with packed column SFC using either pure CO2 or organic solvent modified CO2 as mobile phases. Factors which were expected to affect the interface between SFC and CNLSD were optimized for the detector to reach low detection limits. With SFC using pure CO2 as mobile phase, the detection limit of CNLSD with SFC was observed to be at low nanogram levels, which was at the same level of flame ionization detection (FID) coupled with SFC. For SFC using modified CO2 as mobile phase, detection limits at the picogram level were observed for CNLSD at optimal conditions, which were at least ten times lower than those reached by evaporative light scattering detection. In the second part, particle size distributions of aerosols produced from rapid expansion of supercritical solutions were measured with a scanning mobility particle sizer. The effect of the factors, which were investigated in the first part for their effects on signal intensities and signal to noise ratios (S/N), on particle size distributions (PSDs) of both analyte and background were investigated. Whenever possible, both particle sizes and particle number obtained from PSDs were used to explain the optimization results. In general, PSD data support the observations made in the first part. The detection limits of CNLSD obtained were much higher than predicted. PSDs did not provide direct explanation of this problem. The amount of analyte deposited in the transport tubing, evaporated to gas phase, and condensed to form particles was determined experimentally. Almost no analyte was found in the gas phase. Less than 3% was found in the particle forms. The vast majority of analyte was lost in the transport tubing, especially in the short distance after supercritical fluid expansion. A mechanism was proposed to explain the loss of analyte in the transport tubing.

Aflatoxin M₁ in raw milk from different regions of São Paulo state--Brazil.

PubMed

Santili, Ana Beatriz Nappi; de Camargo, Adriano Costa; Nunes, Raquel de Syllos Rosa; da Gloria, Eduardo Micotti; Machado, Paulo Fernando; Cassoli, Laerte Dagher; Dias, Carlos Tadeu dos Santos; Calori-Domingues, Maria Antonia

2015-01-01

A total of 635 raw milk samples from 45 dairy farms, from three regions of São Paulo state - Brazil, were evaluated during 15 months for aflatoxin M1 (AFM1). AFM1 was determined by high performance liquid chromatograph with fluorescence detection. AFM1 was detected (>0.003 µg kg(-1)) in 72.9%, 56.3% and 27.5% of the samples from Bauru, Araçatuba and Vale do Paraíba regions, respectively. The mean AFM1 contamination considering all the samples was 0.021 µg kg(-1). Furthermore, the concentration of AFM1 was quite different among Bauru (0.038 µg kg(-1)), Araçatuba (0.017 µg kg(-1)) and Vale do Paraíba (<0.01 µg kg(-1)) regions. Only three samples (0.5%) had higher contamination than the tolerated limit in Brazil (0.50 µg kg(-1)) and 64 samples (10.1%) had a higher contamination than the maximum limit as set by the European Union (0.050 µg kg(-1)). The estimated AFM1 daily intake was 0.358 and 0.120 ng kg(-1) body weight per day for children and adults, respectively.

Analysis of PAEs contaminants in water sources for agriculture, industrial and residential areas from local city district

NASA Astrophysics Data System (ADS)

Chen, Qidan; Chen, Qixian; Wu, Fei; Liao, Jia; Zhao, Xi

2018-02-01

The technology of DEHP and DBP detection by high performance liquid chromatography coupled with ultraviolet detection (HPLC-UV) was developed and applied in analysis of local water sources from agriculture, industrial and residential areas. Under the optimized sample pretreatment and detection conditions, DEHP and DBP were well separated and detected in 4 mins. The detection limit of DBP was 0.002 mg/L and DEHP was 0.006 mg/L, and it meets the Chinese National Standard limitations for drinking water quality. The linear correlation coefficient of DBP and DEHP standard calibration curves was 0.9998 and 0.9995. The linear range of DBP was 0.020 mg/L ∼20.0 mg/L, with the standard deviation of 0.560% ∼5.07%, and the linear range of DEHP was 0.060 mg/L ∼15.0 mg/L, with the standard deviation of 0.546% ∼5.74%. Ten water samples from Jinwan district of Zhuhai in Guangdong province of China were analyzed. However, the PAEs amounts found in the water sources from industrial areas were higher than the agriculture and residential areas, industries grow incredibly fast in the district in recently years and more attention should be paid to the increasing risks of water sources pollution.

Laser-Induced Fluorescence Emission (L.I.F.E.): searching for Mars organics with a UV-enhanced PanCam.

PubMed

Storrie-Lombardi, Michael C; Muller, Jan-Peter; Fisk, Martin R; Cousins, Claire; Sattler, Birgit; Griffiths, Andrew D; Coates, Andrew J

2009-12-01

The European Space Agency will launch the ExoMars mission in 2016 with a primary goal of surveying the martian subsurface for evidence of organic material. We have recently investigated the utility of including either a 365 nm light-emitting diode or a 375 nm laser light source in the ExoMars rover panoramic camera (PanCam). Such a modification would make it feasible to monitor rover drill cuttings optically for the fluorescence signatures of aromatic organic molecules and map the distribution of polycyclic aromatic hydrocarbons (PAHs) as a function of depth to the 2 m limit of the ExoMars drill. The technique described requires no sample preparation, does not consume irreplaceable resources, and would allow mission control to prioritize deployment of organic detection experiments that require sample destruction, expenditure of non-replaceable consumables, or both. We report here for the first time laser-induced fluorescence emission (L.I.F.E.) imaging detection limits for anthracene, pyrene, and perylene targets doped onto a Mars analog granular peridotite with a 375 nm Nichia laser diode in optically uncorrected wide-angle mode. Data were collected via the Beagle 2 PanCam backup filter wheel fitted with original blue (440 nm), green (530 nm), and red (670 nm) filters. All three PAH species can be detected with the PanCam green (530 nm) filter. Detection limits in the green band for signal-to-noise ratios (S/N) > 10 are 49 parts per million (ppm) for anthracene, 145 ppm for pyrene, and 20 ppm for perylene. The anthracene detection limit improves to 7 ppm with use of the PanCam blue filter. We discuss soil-dependent detection limit constraints; use of UV excitation with other rover cameras, which provides higher spatial resolution; and the advantages of focused and wide-angle laser modes. Finally, we discuss application of L.I.F.E. techniques at multiple wavelengths for exploration of Mars analog extreme environments on Earth, including Icelandic hydrothermally altered basalts and the ice-covered lakes and glaciers of Dronning Maud Land, Antarctica.

SISGR: Room Temperature Single-Molecule Detection and Imaging by Stimulated Emission Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Xiaoliang Sunney

Single-molecule spectroscopy has made considerable impact on many disciplines including chemistry, physics, and biology. To date, most single-molecule spectroscopy work is accomplished by detecting fluorescence. On the other hand, many naturally occurring chromophores, such as retinal, hemoglobin and cytochromes, do not have detectable fluorescence. There is an emerging need for single-molecule spectroscopy techniques that do not require fluorescence. In the last proposal period, we have successfully demonstrated stimulated emission microscopy, single molecule absorption, and stimulated Raman microscopy based on a high-frequency modulation transfer technique. These first-of-a- kind new spectroscopy/microscopy methods tremendously improved our ability to observe molecules that fluorescence weakly,more » even to the limit of single molecule detection for absorption measurement. All of these methods employ two laser beams: one (pump beam) excites a single molecule to a real or virtual excited state, and the other (probe beam) monitors the absorption/emission property of the single. We extract the intensity change of the probe beam with high sensitivity by implementing a high-frequency phase-sensitive detection scheme, which offers orders of magnitude improvement in detection sensitivity over direct absorption/emission measurement. However, single molecule detection based on fluorescence or absorption is fundamentally limited due to their broad spectral response. It is important to explore other avenues in single molecule detection and imaging which provides higher molecular specificity for studying a wide variety of heterogeneous chemical and biological systems. This proposal aimed to achieve single-molecule detection sensitivity with near resonance stimulated Raman scattering (SRS) microscopy. SRS microscopy was developed in our lab as a powerful technique for imaging heterogeneous samples based on their intrinsic vibrational contrasts, which provides much higher molecular specificity than absorption and fluorescence. Current sensitivity limit of SRS microscopy has not yet reached single molecule detection. We proposed to capitalize on our state-of-the-art SRS microscopy and develop near-resonance enhanced SRS for single molecule detection of carotenoids and heme proteins. The specific aims we pursued are: (1) building the next SRS generation microscope that utilizes near resonance enhancement to allow detection and imaging of single molecules with undetectable fluorescence, such as -carotene. (2) using near-resonance SRS as a contrast mechanism to study dye-sensitize semiconductor interface, elucidating the heterogeneous electron ejection kinetics with high spatial and temporal resolution. (3) studying the binding and unbinding of oxygen in single hemoglobin molecules in order to gain molecular level understanding of the long-standing issue of cooperativity. The new methods developed in the fund period of this grant have advanced the detection sensitivity in many aspects. Near-resonance SRS improved the signal by using shorter wavelengths for SRS microscopy. Frequency modulation and multi-color SRS target the reduction of background to improve the chemical specificity of SRS while maintaining the high imaging speed. Time-domain coherent Raman scattering microscopy targets to reduce the noise floor of coherent Raman microscopy. These methods have already demonstrated first-of-a-kind new applications in biology and medical research. However, we are still one order of magnitude away from single molecule limit. It is important to continue to improve the laser specification and develop new imaging methods to finally achieve label-free single molecule microscopy.« less

ON THE STAR FORMATION PROPERTIES OF VOID GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moorman, Crystal M.; Moreno, Jackeline; White, Amanda

2016-11-10

We measure the star formation properties of two large samples of galaxies from the SDSS in large-scale cosmic voids on timescales of 10 and 100 Myr, using H α emission line strengths and GALEX FUV fluxes, respectively. The first sample consists of 109,818 optically selected galaxies. We find that void galaxies in this sample have higher specific star formation rates (SSFRs; star formation rates per unit stellar mass) than similar stellar mass galaxies in denser regions. The second sample is a subset of the optically selected sample containing 8070 galaxies with reliable H i detections from ALFALFA. For the fullmore » H i detected sample, SSFRs do not vary systematically with large-scale environment. However, investigating only the H i detected dwarf galaxies reveals a trend toward higher SSFRs in voids. Furthermore, we estimate the star formation rate per unit H i mass (known as the star formation efficiency; SFE) of a galaxy, as a function of environment. For the overall H i detected population, we notice no environmental dependence. Limiting the sample to dwarf galaxies still does not reveal a statistically significant difference between SFEs in voids versus walls. These results suggest that void environments, on average, provide a nurturing environment for dwarf galaxy evolution allowing for higher specific star formation rates while forming stars with similar efficiencies to those in walls.« less

Rapid and Highly Sensitive Detection of Lead Ions in Drinking Water Based on a Strip Immunosensor

PubMed Central

Kuang, Hua; Xing, Changrui; Hao, Changlong; Liu, Liqiang; Wang, Libing; Xu, Chuanlai

2013-01-01

In this study, we have first developed a rapid and sensitive strip immunosensor based on two heterogeneously-sized gold nanoparticles (Au NPs) probes for the detection of trace lead ions in drinking water. The sensitivity was 4-fold higher than that of the conventional LFA under the optimized conditions. The visual limit of detection (LOD) of the amplified method for qualitative detection lead ions was 2 ng/mL and the LOD for semi-quantitative detection could go down to 0.19 ng/mL using a scanning reader. The method suffered from no interference from other metal ions and could be used to detect trace lead ions in drinking water without sample enrichment. The recovery of the test samples ranged from 96% to 103%. As the detection method could be accomplished within 15 min, this method could be used as a potential tool for preliminary monitoring of lead contamination in drinking water. PMID:23539028

[Detection of KRAS mutation in colorectal cancer patients' cfDNA with droplet digital PCR].

PubMed

Luo, Yuwen; Li, Yao

2018-03-25

This study aims to develop a new method for the detection of KRAS mutations related to colorectal cancer in cfDNA, and to evaluate the sensitivity and accuracy of the detection. We designed a method of cfDNA based KRAS detection by droplets digital PCR (ddPCR). The theoretical performance of the method is evaluated by reference standard and compared to the ARMS PCR method. Two methods, ddPCR and qPCR, were successfully established to detect KRAS wild type and 7 mutants. Both methods were validated using plasmid standards and actual samples. The results were evaluated by false positive rate, linearity, and limit of detection. Finally, 52 plasma cfDNA samples from patients and 20 samples from healthy people were tested, the clinical sensitivity is 97.64%, clinical specificity is 81.43%. ddPCR method shows higher performance than qPCR. The LOD of ddPCR method reached single digits of cfDNA copies, it can detect as low as 0.01% to 0.04% mutation abundance.

Surface-enhanced Raman spectroscopy detection of polybrominated diphenylethers using a portable Raman spectrometer.

PubMed

Jiang, Xiaohong; Lai, Yongchao; Wang, Wei; Jiang, Wei; Zhan, Jinhua

2013-11-15

Polybrominated diphenylethers (PBDEs), one of the most common brominated flame retardants, are toxic and persistent, generally detected by the chromatographic method. In this work, qualitative and quantitative detection of PBDEs were explored based on surface-enhanced Raman spectroscopy (SERS) technique using a portable Raman spectrometer. Alkanethiol modified silver nanoparticle aggregates were used as the substrate and PBDEs could be pre-concentrated close to the substrate surface through their hydrophobic interactions with alkanethiol. The effect of alkanethiols with different chain length on the SERS detection of PBDEs was evaluated. It was shown that 1-hexanethiol (HT) modified substrate has higher sensitivity, good stability and reusability. Qualitative and quantitative SERS detection of PBDEs in real sea water was accomplished, with the measured detection limits at 1.2×10(2) μg L(-1). These results illustrate SERS could be used as an effective method for the detection of PBDEs. Copyright © 2013 Elsevier B.V. All rights reserved.

VCSEL based Faraday rotation spectroscopy at 762nm for battery powered trace molecular oxygen detection

NASA Astrophysics Data System (ADS)

So, Stephen; Wysocki, Gerard

2010-02-01

Faraday Rotation Spectroscopy (FRS) is a polarization based spectroscopic technique which can provide higher sensitivity concentration measurements of paramagnetic gases and free radicals than direct absorption spectroscopic techniques. We have developed sensor systems which require only 0.2W to perform TDLAS (tunable diode laser absorption spectroscopy), and can additionally be quickly duty cycled, enabling operation in wireless sensor networks of laser-based trace gas sensors We adapted our integrated TDLAS electronics to perform FRS in a compact and more sensitive system for quantification of molecular oxygen (O2) using a 762.3nm VCSEL in the A band. Using an AC magnetic field, we demonstrate detector noise dominated performance, achieving 2.1×10-6/Hz1/2 equivalent detectable fractional absorption and a minimum detection limit of 462 ppmv O2 in 1 second in a 15cm path. At longer paths and integration times, such a sensor will enable oxygen measurements at biotic respiration levels (<1ppmv) to measure CO2 - O2 exchange for mapping natural exchange of greenhouse gases. Potential improvement of detection limits by increasing various system performance parameters is described.

Photoacoustic and photothermal detection of circulating tumor cells, bacteria and nanoparticles in cerebrospinal fluid in vivo and ex vivo.

PubMed

Nedosekin, Dmitry A; Juratli, Mazen A; Sarimollaoglu, Mustafa; Moore, Christopher L; Rusch, Nancy J; Smeltzer, Mark S; Zharov, Vladimir P; Galanzha, Ekaterina I

2013-06-01

Circulating cells, bacteria, proteins, microparticles, and DNA in cerebrospinal fluid (CSF) are excellent biomarkers of many diseases, including cancer and infections. However, the sensitivity of existing methods is limited in their ability to detect rare CSF biomarkers at the treatable, early-stage of diseases. Here, we introduce novel CSF tests based on in vivo photoacoustic flow cytometry (PAFC) and ex vivo photothermal scanning cytometry. In the CSF of tumor-bearing mice, we molecularly detected in vivo circulating tumor cells (CTCs) before the development of breast cancer brain metastasis with 20-times higher sensitivity than with current assays. For the first time, we demonstrated assessing three pathways (i.e., blood, lymphatic, and CSF) of CTC dissemination, tracking nanoparticles in CSF in vivo and their imaging ex vivo. In label-free CSF samples, we counted leukocytes, erythrocytes, melanoma cells, and bacteria and imaged intracellular cytochromes, hemoglobin, melanin, and carotenoids, respectively. Taking into account the safety of PAFC, its translation for use in humans is expected to improve disease diagnosis beyond conventional detection limits. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flexible Ag-C60 nano-biosensors based on surface plasmon coupled emission for clinical and forensic applications.

PubMed

Mulpur, Pradyumna; Yadavilli, Sairam; Mulpur, Praharsha; Kondiparthi, Neeharika; Sengupta, Bishwambhar; Rao, Apparao M; Podila, Ramakrishna; Kamisetti, Venkataramaniah

2015-10-14

The relatively low sensitivity of fluorescence detection schemes, which are mainly limited by the isotropic nature of fluorophore emission, can be overcome by utilizing surface plasmon coupled emission (SPCE). In this study, we demonstrate directional emission from fluorophores on flexible Ag-C60 SPCE sensor platforms for point-of-care sensing, in healthcare and forensic sensing scenarios, with at least 10 times higher sensitivity than traditional fluorescence sensing schemes. Adopting the highly sensitive Ag-C60 SPCE platform based on glass and novel low-cost flexible substrates, we report the unambiguous detection of acid-fast Mycobacterium tuberculosis (Mtb) bacteria at densities as low as 20 Mtb mm(-2); from non-acid-fast bacteria (e.g., E. coli and S. aureus), and the specific on-site detection of acid-fast sperm cells in human semen samples. In combination with the directional emission and high-sensitivity of SPCE platforms, we also demonstrate the utility of smartphones that can replace expensive and cumbersome detectors to enable rapid hand-held detection of analytes in resource-limited settings; a much needed critical advance to biosensors, for developing countries.

Rapid and sensitive detection of Lily symptomless virus by reverse transcription loop-mediated isothermal amplification.

PubMed

He, Xiangfeng; Xue, Fei; Xu, Shufa; Wang, Wenhe

2016-12-01

Lily symptomless virus (LSV) is one of the most prevalent viruses that infect lily plants worldwide. A rapid and sensitive reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for detection of LSV, using two primer pairs that specifically amplified the conserved sequence of LSV coat protein. The optimum reaction conditions were as follows: 4mM MgCl 2 and 0.8M betaine with incubation at 64°C for 30min. The limit of detection of LSV from infected lily leaves was 10-fold higher for RT-LAMP than for conventional RT-PCR. Moreover, RT-LAMP detected LSV in not only symptomatic, but also in symptomless tissues of infected plants. These findings indicate that our RT-LAMP method for LSV can serve as a low-cost, simple, and rapid alternative to conventional detection assays. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of Engineered Bacteriophages for Escherichia coli Detection and High-Throughput Antibiotic Resistance Determination.

PubMed

Chen, Juhong; Alcaine, Samuel D; Jackson, Angelyca A; Rotello, Vincent M; Nugen, Sam R

2017-04-28

T7 bacteriophages (phages) have been genetically engineered to carry the lacZ operon, enabling the overexpression of beta-galactosidase (β-gal) during phage infection and allowing for the enhanced colorimetric detection of Escherichia coli (E. coli). Following the phage infection of E. coli, the enzymatic activity of the released β-gal was monitored using a colorimetric substrate. Compared with a control T7 phage, our T7 lacZ phage generated significantly higher levels of β-gal expression following phage infection, enabling a lower limit of detection for E. coli cells. Using this engineered T7 lacZ phage, we were able to detect E. coli cells at 10 CFU·mL -1 within 7 h. Furthermore, we demonstrated the potential for phage-based sensing of bacteria antibiotic resistance profiling using our T7 lacZ phage, and subsequent β-gal expression to detect antibiotic resistant profile of E. coli strains.

Detection limits of quantitative and digital PCR assays and their influence in presence-absence surveys of environmental DNA.

PubMed

Hunter, Margaret E; Dorazio, Robert M; Butterfield, John S S; Meigs-Friend, Gaia; Nico, Leo G; Ferrante, Jason A

2017-03-01

A set of universal guidelines is needed to determine the limit of detection (LOD) in PCR-based analyses of low-concentration DNA. In particular, environmental DNA (eDNA) studies require sensitive and reliable methods to detect rare and cryptic species through shed genetic material in environmental samples. Current strategies for assessing detection limits of eDNA are either too stringent or subjective, possibly resulting in biased estimates of species' presence. Here, a conservative LOD analysis grounded in analytical chemistry is proposed to correct for overestimated DNA concentrations predominantly caused by the concentration plateau, a nonlinear relationship between expected and measured DNA concentrations. We have used statistical criteria to establish formal mathematical models for both quantitative and droplet digital PCR. To assess the method, a new Grass Carp (Ctenopharyngodon idella) TaqMan assay was developed and tested on both PCR platforms using eDNA in water samples. The LOD adjustment reduced Grass Carp occupancy and detection estimates while increasing uncertainty-indicating that caution needs to be applied to eDNA data without LOD correction. Compared to quantitative PCR, digital PCR had higher occurrence estimates due to increased sensitivity and dilution of inhibitors at low concentrations. Without accurate LOD correction, species occurrence and detection probabilities based on eDNA estimates are prone to a source of bias that cannot be reduced by an increase in sample size or PCR replicates. Other applications also could benefit from a standardized LOD such as GMO food analysis and forensic and clinical diagnostics. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Cross-platform evaluation of commercial real-time SYBR green RT-PCR kits for sensitive and rapid detection of European bat Lyssavirus type 1.

PubMed

Picard-Meyer, Evelyne; Peytavin de Garam, Carine; Schereffer, Jean Luc; Marchal, Clotilde; Robardet, Emmanuelle; Cliquet, Florence

2015-01-01

This study evaluates the performance of five two-step SYBR Green RT-qPCR kits and five one-step SYBR Green qRT-PCR kits using real-time PCR assays. Two real-time thermocyclers showing different throughput capacities were used. The analysed performance evaluation criteria included the generation of standard curve, reaction efficiency, analytical sensitivity, intra- and interassay repeatability as well as the costs and the practicability of kits, and thermocycling times. We found that the optimised one-step PCR assays had a higher detection sensitivity than the optimised two-step assays regardless of the machine used, while no difference was detected in reaction efficiency, R (2) values, and intra- and interreproducibility between the two methods. The limit of detection at the 95% confidence level varied between 15 to 981 copies/µL and 41 to 171 for one-step kits and two-step kits, respectively. Of the ten kits tested, the most efficient kit was the Quantitect SYBR Green qRT-PCR with a limit of detection at 95% of confidence of 20 and 22 copies/µL on the thermocyclers Rotor gene Q MDx and MX3005P, respectively. The study demonstrated the pivotal influence of the thermocycler on PCR performance for the detection of rabies RNA, as well as that of the master mixes.

Gold nanoparticle-based enzyme-linked antibody-aptamer sandwich assay for detection of Salmonella Typhimurium.

PubMed

Wu, Wenhe; Li, Jun; Pan, Dun; Li, Jiang; Song, Shiping; Rong, Mingge; Li, Zixi; Gao, Jimin; Lu, Jianxin

2014-10-08

Enzyme-linked immunosorbent assay (ELISA) provides a convenient means for the detection of Salmonella enterica serovar Typhimurium (STM), which is important for rapid diagnosis of foodborne pathogens. However, conventional ELISA is limited by antibody-antigen immunoreactions and suffers from poor sensitivity and tedious sample pretreatment. Therefore, development of novel ELISA remains challenging. Herein, we designed a comprehensive strategy for rapid, sensitive, and quantitative detection of STM with high specificity by gold nanoparticle-based enzyme-linked antibody-aptamer sandwich (nano-ELAAS) method. STM was captured and preconcentrated from samples with aptamer-modified magnetic particles, followed by binding with detector antibodies. Then nanoprobes carrying a large amount of reporter antibodies and horseradish peroxidase molecules were used for colorimetric signal amplification. Under the optimized reaction conditions, the nano-ELAAS assay had a quantitative detection range from 1 × 10(3) to 1 × 10(8) CFU mL(-1), a limit of detection of 1 × 10(3) CFU mL(-1), and a selectivity of >10-fold for STM in samples containing other bacteria at higher concentration with an assay time less than 3 h. In addition, the developed nanoprobes were improved in terms of detection range and/or sensitivity when compared with two commercial enzyme-labeled antibody signal reporters. Finally, the nano-ELAAS method was demonstrated to work well in milk samples, a common source of STM contamination.

Cross-Platform Evaluation of Commercial Real-Time SYBR Green RT-PCR Kits for Sensitive and Rapid Detection of European Bat Lyssavirus Type 1

PubMed Central

Picard-Meyer, Evelyne; Peytavin de Garam, Carine; Schereffer, Jean Luc; Marchal, Clotilde; Robardet, Emmanuelle; Cliquet, Florence

2015-01-01

This study evaluates the performance of five two-step SYBR Green RT-qPCR kits and five one-step SYBR Green qRT-PCR kits using real-time PCR assays. Two real-time thermocyclers showing different throughput capacities were used. The analysed performance evaluation criteria included the generation of standard curve, reaction efficiency, analytical sensitivity, intra- and interassay repeatability as well as the costs and the practicability of kits, and thermocycling times. We found that the optimised one-step PCR assays had a higher detection sensitivity than the optimised two-step assays regardless of the machine used, while no difference was detected in reaction efficiency, R 2 values, and intra- and interreproducibility between the two methods. The limit of detection at the 95% confidence level varied between 15 to 981 copies/µL and 41 to 171 for one-step kits and two-step kits, respectively. Of the ten kits tested, the most efficient kit was the Quantitect SYBR Green qRT-PCR with a limit of detection at 95% of confidence of 20 and 22 copies/µL on the thermocyclers Rotor gene Q MDx and MX3005P, respectively. The study demonstrated the pivotal influence of the thermocycler on PCR performance for the detection of rabies RNA, as well as that of the master mixes. PMID:25785274

Combining satellite-based fire observations and ground-based lightning detections to identify lightning fires across the conterminous USA

USGS Publications Warehouse

Bar-Massada, A.; Hawbaker, T.J.; Stewart, S.I.; Radeloff, V.C.

2012-01-01

Lightning fires are a common natural disturbance in North America, and account for the largest proportion of the area burned by wildfires each year. Yet, the spatiotemporal patterns of lightning fires in the conterminous US are not well understood due to limitations of existing fire databases. Our goal here was to develop and test an algorithm that combined MODIS fire detections with lightning detections from the National Lightning Detection Network to identify lightning fires across the conterminous US from 2000 to 2008. The algorithm searches for spatiotemporal conjunctions of MODIS fire clusters and NLDN detected lightning strikes, given a spatiotemporal lag between lightning strike and fire ignition. The algorithm revealed distinctive spatial patterns of lightning fires in the conterminous US While a sensitivity analysis revealed that the algorithm is highly sensitive to the two thresholds that are used to determine conjunction, the density of fires it detected was moderately correlated with ground based fire records. When only fires larger than 0.4 km2 were considered, correlations were higher and the root-mean-square error between datasets was less than five fires per 625 km2 for the entire study period. Our algorithm is thus suitable for detecting broad scale spatial patterns of lightning fire occurrence, and especially lightning fire hotspots, but has limited detection capability of smaller fires because these cannot be consistently detected by MODIS. These results may enhance our understanding of large scale patterns of lightning fire activity, and can be used to identify the broad scale factors controlling fire occurrence.

Planck 2015 results. XXVI. The Second Planck Catalogue of Compact Sources

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Argüeso, F.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Beichman, C.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Böhringer, H.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Carvalho, P.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chiang, H. C.; Christensen, P. R.; Clemens, M.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leahy, J. P.; Leonardi, R.; León-Tavares, J.; Lesgourgues, J.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Negrello, M.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Sanghera, H. S.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Stolyarov, V.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tornikoski, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Türler, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Walter, B.; Wandelt, B. D.; Wehus, I. K.; Yvon, D.; Zacchei, A.; Zonca, A.

2016-09-01

The Second Planck Catalogue of Compact Sources is a list of discrete objects detected in single-frequency maps from the full duration of the Planck mission and supersedes previous versions. It consists of compact sources, both Galactic and extragalactic, detected over the entire sky. Compact sources detected in the lower frequency channels are assigned to the PCCS2, while at higher frequencies they are assigned to one of two subcatalogues, the PCCS2 or PCCS2E, depending on their location on the sky. The first of these (PCCS2) covers most of the sky and allows the user to produce subsamples at higher reliabilities than the target 80% integral reliability of the catalogue. The second (PCCS2E) contains sources detected in sky regions where the diffuse emission makes it difficult to quantify the reliability of the detections. Both the PCCS2 and PCCS2E include polarization measurements, in the form of polarized flux densities, or upper limits, and orientation angles for all seven polarization-sensitive Planck channels. The improved data-processing of the full-mission maps and their reduced noise levels allow us to increase the number of objects in the catalogue, improving its completeness for the target 80% reliability as compared with the previous versions, the PCCS and the Early Release Compact Source Catalogue (ERCSC).

Nanotechnology: moving from microarrays toward nanoarrays.

PubMed

Chen, Hua; Li, Jun

2007-01-01

Microarrays are important tools for high-throughput analysis of biomolecules. The use of microarrays for parallel screening of nucleic acid and protein profiles has become an industry standard. A few limitations of microarrays are the requirement for relatively large sample volumes and elongated incubation time, as well as the limit of detection. In addition, traditional microarrays make use of bulky instrumentation for the detection, and sample amplification and labeling are quite laborious, which increase analysis cost and delays the time for obtaining results. These problems limit microarray techniques from point-of-care and field applications. One strategy for overcoming these problems is to develop nanoarrays, particularly electronics-based nanoarrays. With further miniaturization, higher sensitivity, and simplified sample preparation, nanoarrays could potentially be employed for biomolecular analysis in personal healthcare and monitoring of trace pathogens. In this chapter, it is intended to introduce the concept and advantage of nanotechnology and then describe current methods and protocols for novel nanoarrays in three aspects: (1) label-free nucleic acids analysis using nanoarrays, (2) nanoarrays for protein detection by conventional optical fluorescence microscopy as well as by novel label-free methods such as atomic force microscopy, and (3) nanoarray for enzymatic-based assay. These nanoarrays will have significant applications in drug discovery, medical diagnosis, genetic testing, environmental monitoring, and food safety inspection.

Detection limits and cost comparisons of human- and gull-associated conventional and quantitative PCR assays in artificial and environmental waters.

PubMed

Riedel, Timothy E; Zimmer-Faust, Amity G; Thulsiraj, Vanessa; Madi, Tania; Hanley, Kaitlyn T; Ebentier, Darcy L; Byappanahalli, Muruleedhara; Layton, Blythe; Raith, Meredith; Boehm, Alexandria B; Griffith, John F; Holden, Patricia A; Shanks, Orin C; Weisberg, Stephen B; Jay, Jennifer A

2014-04-01

Some molecular methods for tracking fecal pollution in environmental waters have both PCR and quantitative PCR (qPCR) assays available for use. To assist managers in deciding whether to implement newer qPCR techniques in routine monitoring programs, we compared detection limits (LODs) and costs of PCR and qPCR assays with identical targets that are relevant to beach water quality assessment. For human-associated assays targeting Bacteroidales HF183 genetic marker, qPCR LODs were 70 times lower and there was no effect of target matrix (artificial freshwater, environmental creek water, and environmental marine water) on PCR or qPCR LODs. The PCR startup and annual costs were the lowest, while the per reaction cost was 62% lower than the Taqman based qPCR and 180% higher than the SYBR based qPCR. For gull-associated assays, there was no significant difference between PCR and qPCR LODs, target matrix did not effect PCR or qPCR LODs, and PCR startup, annual, and per reaction costs were lower. Upgrading to qPCR involves greater startup and annual costs, but this increase may be justified in the case of the human-associated assays with lower detection limits and reduced cost per sample. Copyright © 2014 Elsevier Ltd. All rights reserved.

New Astrometric Limits on the Stochastic Gravitational Wave Background

NASA Astrophysics Data System (ADS)

Darling, Jeremiah K.; Truebenbach, Alexandra; Paine, Jennie

2018-06-01

We present new limits on the low frequency (f < 10-8 Hz) stochastic gravitational wave background using correlated extragalactic proper motions. The familiar methods for gravitational wave detection are ground- and space-based laser interferometry, pulsar timing, and polarization of the cosmic microwave background. Astrometry offers an additional path to gravitational wave detection because gravitational waves deflect the light rays of extragalactic objects, creating apparent proper motions in a quadrupolar (and higher order modes) pattern. Astrometry is sensitive to gravitational waves with frequencies between roughly 10-18 Hz and 10-8 Hz (between H0 and 1/3 yr-1), which overlaps and bridges the pulsar timing and CMB polarization regimes. We present the methods and results of two complementary approaches to astrometric gravitational wave detection: (1) a small ~500-object radio interferometric sample with low per-source proper motion uncertainty but large intrinsic proper motions caused by radio jets, and (2) a thousand-fold larger sample with large per-source uncertainties that has small intrinsic proper motions (Gaia active galactic nuclei). Both approaches produce limits on ΩGW, the energy density of gravitational waves as a fraction of the cosmological critical energy density.The authors acknowledge support from the NSF grant AST-1411605 and the NASA grant 14-ATP14-0086.

Detection limits and cost comparisons of human- and gull-associated conventional and quantitative PCR assays in artificial and environmental waters

USGS Publications Warehouse

Riedel, Timothy E.; Zimmer-Faust, Amity G.; Thulsiraj, Vanessa; Madi, Tania; Hanley, Kaitlyn T.; Ebentier, Darcy L.; Byappanahalli, Muruleedhara N.; Layton, Blythe; Raith, Meredith; Boehm, Alexandria B.; Griffith, John F.; Holden, Patricia A.; Shanks, Orin C.; Weisberg, Stephen B.; Jay, Jennifer A.

2014-01-01

Some molecular methods for tracking fecal pollution in environmental waters have both PCR and quantitative PCR (qPCR) assays available for use. To assist managers in deciding whether to implement newer qPCR techniques in routine monitoring programs, we compared detection limits (LODs) and costs of PCR and qPCR assays with identical targets that are relevant to beach water quality assessment. For human-associated assays targeting Bacteroidales HF183 genetic marker, qPCR LODs were 70 times lower and there was no effect of target matrix (artificial freshwater, environmental creek water, and environmental marine water) on PCR or qPCR LODs. The PCR startup and annual costs were the lowest, while the per reaction cost was 62% lower than the Taqman based qPCR and 180% higher than the SYBR based qPCR. For gull-associated assays, there was no significant difference between PCR and qPCR LODs, target matrix did not effect PCR or qPCR LODs, and PCR startup, annual, and per reaction costs were lower. Upgrading to qPCR involves greater startup and annual costs, but this increase may be justified in the case of the human-associated assays with lower detection limits and reduced cost per sample.

Real-time label-free biosensing with integrated planar waveguide ring resonators

NASA Astrophysics Data System (ADS)

Sohlström, Hans; Gylfason, Kristinn B.; Hill, Daniel

2010-05-01

We review the use of planar integrated optical waveguide ring resonators for label free bio-sensing and present recent results from two European biosensor collaborations: SABIO and InTopSens. Planar waveguide ring resonators are attractive for label-free biosensing due to their small footprint, high Q-factors, and compatibility with on-chip optics and microfluidics. This enables integrated sensor arrays for compact labs-on-chip. One application of label-free sensor arrays is for point-of-care medical diagnostics. Bringing such powerful tools to the single medical practitioner is an important step towards personalized medicine, but requires addressing a number of issues: improving limit of detection, managing the influence of temperature, parallelization of the measurement for higher throughput and on-chip referencing, efficient light-coupling strategies to simplify alignment, and packaging of the optical chip and integration with microfluidics. From the SABIO project we report refractive index measurement and label-free biosensing in an 8-channel slotwaveguide ring resonator sensor array, within a compact cartridge with integrated microfluidics. The sensors show a volume sensing detection limit of 5 x 10-6 RIU and a surface sensing detection limit of 0.9 pg/mm2. From the InTopSens project we report early results on silicon-on-insulator racetrack resonators.

Silver(I) Ions Ultrasensitive Detection at Carbon Electrodes—Analysis of Waters, Tobacco Cells and Fish Tissues

PubMed Central

Krizkova, Sona; Krystofova, Olga; Trnkova, Libuse; Hubalek, Jaromir; Adam, Vojtech; Beklova, Miroslava; Horna, Ales; Havel, Ladislav; Kizek, Rene

2009-01-01

We used carbon paste electrodes and a standard potentiostat to detect silver ions. The detection limit (3 Signal/Noise ratio) was estimated as 0.5 μM. A standard electrochemical instrument microanalysis of silver(I) ions was suggested. As a working electrode a carbon tip (1 mL) or carbon pencil was used. Limits of detection estimated by dilution of a standard were 1 (carbon tip) or 10 nM (carbon pencil). Further we employed flow injection analysis coupled with carbon tip to detect silver(I) ions released in various beverages and mineral waters. During first, second and third week the amount of silver(I) ions releasing into water samples was under the detection limit of the technique used for their quantification. At the end of a thirteen weeks long experiment the content of silver(I) ions was several times higher compared to the beginning of release detected in the third week and was on the order of tens of nanomoles. In subsequent experiments the influence of silver(I) ions (0, 5 and 10 μM) on a plant model system (tobacco BY-2 cells) during a four-day exposition was investigated. Silver(I) ions were highly toxic to the cells, which was revealed by a double staining viability assay. Moreover we investigated the effect of silver(I) ions (0, 0.3, 0.6, 1.2 and 2.5 μM) on guppies (Poecilia reticulata). Content of Ag(I) increased with increasing time of the treatment and applied concentrations in fish tissues. It can be concluded that a carbon tip or carbon pencil coupled with a miniaturized potentiostat can be used for detection of silver(I) ions in environmental samples and thus represents a small, portable, low cost and easy-to-use instrument for such purposes. PMID:22399980

Detectable Viral Load in Late Pregnancy among Women in the Rwanda Option B+ PMTCT Program: Enrollment Results from the Kabeho Study

PubMed Central

Gill, Michelle M.; Hoffman, Heather J.; Bobrow, Emily A.; Mugwaneza, Placidie; Ndatimana, Dieudonne; Ndayisaba, Gilles F.; Baribwira, Cyprien; Guay, Laura; Asiimwe, Anita

2016-01-01

There are limited viral load (VL) data available from programs implementing “Option B+,” lifelong antiretroviral treatment (ART) to all HIV-positive pregnant and postpartum women, in resource-limited settings. Extent of viral suppression from a prevention of mother-to-child transmission of HIV program in Rwanda was assessed among women enrolled in the Kigali Antiretroviral and Breastfeeding Assessment for the Elimination of HIV (Kabeho) Study. ARV drug resistance testing was conducted on women with VL>2000 copies/ml. In April 2013-January 2014, 608 pregnant or early postpartum HIV-positive women were enrolled in 14 facilities. Factors associated with detectable enrollment VL (>20 copies/ml) were examined using generalized estimating equations. The most common antiretroviral regimen (56.7%, 344/607) was tenofovir/lamivudine/efavirenz. Median ART duration was 13.5 months (IQR 3.0–48.8); 76.1% of women were on ART at first antenatal visit. Half of women (315/603) had undetectable RNA-PCR VL and 84.6% (510) had <1,000 copies/ml. Detectable VL increased among those on ART > 36 months compared to those on ART 4–36 months (72/191, 37.7% versus 56/187, 29.9%), though the difference was not significant. The odds of having detectable enrollment VL decreased significantly as duration on ART at enrollment increased (AOR = 0.99, 95% CI: 0.9857, 0.9998, p = 0.043). There was a higher likelihood of detectable VL for women with lower gravidity (AOR = 0.90, 95% CI: 0.84, 0.97, p = 0.0039), no education (AOR = 2.25, (95% CI: 1.37, 3.70, p = 0.0004), nondisclosure to partner (AOR = 1.97, 95% CI: 1.21, 3.21, p = 0.0063) and side effects (AOR = 2.63, 95% CI: 1.72, 4.03, p<0.0001). ARV drug resistance mutations were detected in all of the eleven women on ART > 36 months with genotyping available. Most women were receiving ART at first antenatal visit, with relatively high viral suppression rates. Shorter ART duration was associated with higher VL, with a concerning increasing trend for higher viremia and drug resistance among women on ART for >3 years. PMID:28006001

Application of the desulfurization of phenothiazines for a sensitive detection method by high-performance liquid chromatography.

PubMed

Shimada, K; Mino, T; Nakajima, M; Wakabayashi, H; Yamato, S

1994-11-04

A simple and sensitive high-performance liquid chromatographic (HPLC) method for the determination of phenothiazine (PHE) is described. PHE is converted to diphenylamine (DIP) by desulfurization with Raney nickel catalyst. DIP is highly sensitive to electrochemical detection. The calibration graph for PHE quantification after desulfurization was linear between 0.1 and 2.0 ng per injection. The detection limit (signal-to-noise ratio = 3) of PHE after desulfurization was 10 pg, which is twenty times higher than that of the parent compound PHE. The proposed desulfurization technique was applied to other PHE-related compounds. The structural confirmation of the desulfurized product of PHE was carried out by LC-MS using atmospheric pressure chemical ionization.

Pulse oximeter saturation target limits for preterm infants: a survey among European neonatal intensive care units.

PubMed

Huizing, Maurice J; Villamor-Martínez, Eduardo; Vento, Máximo; Villamor, Eduardo

2017-01-01

The optimum range of pulse oximeter oxygen saturation (SpO 2 ) for preterm infants remains controversial. Between November 2015 and February 2016, we conducted a web-based survey aimed to investigate the current and former practices on SpO 2 targets in European neonatal intensive care units (NICUs). We obtained valid responses from 193 NICUs, treating 8590 newborns ≤28 weeks per year, across 27 countries. Forty different saturation ranges were reported, ranging from 82-93 to 94-99%. The most frequently utilized SpO 2 ranges were 90-95% (28%), 88-95% (12%), 90-94% (5%), and 91-95% (5%). A total of 156 NICUs (81%) changed their SpO 2 limits over the last 10 years. The most frequently reported former limits were 88-92% (18%), 85-95% (9%), 88-93 (7%), and 85-92% (6%). The NICUs that increased their SpO 2 ranges expected to obtain a reduction in mortality. A 54% of the NICUs found the scientific evidence supporting their SpO 2 targeting policy strong or very strong. We detected a high degree of heterogeneity in pulse oximeter SpO 2 target limits across European NICUs. The currently used limits are 3 to 5% higher than the former limits, and the most extreme limits, such as lower below 85% or upper above 96%, have almost been abandoned. What is Known: • For preterm infants requiring supplemental oxygen, the optimum range of pulse oximeter oxygen saturation (SpO 2 ) to minimize organ damage, without causing hypoxic injury, remains controversial. What is New: • This survey highlights the lack of consensus regarding SpO 2 target limits for preterm infants among European neonatal intensive care units (NICUs). We detected 40 different SpO 2 ranges, and even the most frequently reported range (i.e., 90-95%) was used in only 28% of the 193 respondent NICUs. • A total of 156 NICUs (81%) changed their SpO 2 limits over the last 10 years. The currently used limits are 3 to 5% higher than the former limits, and the most extreme limits, such as lower below 85% or upper above 96%, have almost been abandoned.

Subpixel target detection and enhancement in hyperspectral images

NASA Astrophysics Data System (ADS)

Tiwari, K. C.; Arora, M.; Singh, D.

2011-06-01

Hyperspectral data due to its higher information content afforded by higher spectral resolution is increasingly being used for various remote sensing applications including information extraction at subpixel level. There is however usually a lack of matching fine spatial resolution data particularly for target detection applications. Thus, there always exists a tradeoff between the spectral and spatial resolutions due to considerations of type of application, its cost and other associated analytical and computational complexities. Typically whenever an object, either manmade, natural or any ground cover class (called target, endmembers, components or class) gets spectrally resolved but not spatially, mixed pixels in the image result. Thus, numerous manmade and/or natural disparate substances may occur inside such mixed pixels giving rise to mixed pixel classification or subpixel target detection problems. Various spectral unmixing models such as Linear Mixture Modeling (LMM) are in vogue to recover components of a mixed pixel. Spectral unmixing outputs both the endmember spectrum and their corresponding abundance fractions inside the pixel. It, however, does not provide spatial distribution of these abundance fractions within a pixel. This limits the applicability of hyperspectral data for subpixel target detection. In this paper, a new inverse Euclidean distance based super-resolution mapping method has been presented that achieves subpixel target detection in hyperspectral images by adjusting spatial distribution of abundance fraction within a pixel. Results obtained at different resolutions indicate that super-resolution mapping may effectively aid subpixel target detection.

Experimental validation and testing of a NaI boron-lined neutron detector

NASA Astrophysics Data System (ADS)

Metwally, Walid A.; Emam, Amira G.

2018-05-01

Effective neutron detection systems are critical in various nuclear fields. Most of the current detection systems rely on He-3 detectors due to their high neutron cross section. However, the limited sizes and worldwide scarcity of He-3 lead to major research efforts to find alternative neutron detectors. One of the proposed cost-effective alternatives is using boron-lined NaI detectors to detect the gamma ray resulting from the 10B(n,α)7Li reaction. The proposed detector assembly has been experimentally tested and its results were compared with those from a He-3 detector. In addition to detecting the gamma rays from the source and surrounding medium, the boron-lined NaI detector showed a good sensitivity to changes in neutron flux distributions and a higher efficiency when compared to the He-3 detector used.

Multi-Channel Hyperspectral Fluorescence Detection Excited by Coupled Plasmon-Waveguide Resonance

PubMed Central

Du, Chan; Liu, Le; Zhang, Lin; Guo, Jun; Guo, Jihua; Ma, Hui; He, Yonghong

2013-01-01

We propose in this paper a biosensor scheme based on coupled plasmon-waveguide resonance (CPWR) excited fluorescence spectroscopy. A symmetrical structure that offers higher surface electric field strengths, longer surface propagation lengths and depths is developed to support guided waveguide modes for the efficient excitation of fluorescence. The optimal parameters for the sensor films are theoretically and experimentally investigated, leading to a detection limit of 0.1 nM (for a Cy5 solution). Multiplex analysis possible with the fluorescence detection is further advanced by employing the hyperspectral fluorescence technique to record the full spectra for every pixel on the sample plane. We demonstrate experimentally that highly overlapping fluorescence (Cy5 and Dylight680) can be distinguished and ratios of different emission sources can be determined accurately. This biosensor shows great potential for multiplex detections of fluorescence analytes. PMID:24129023

Electrochemical Detection in Stacked Paper Networks.

PubMed

Liu, Xiyuan; Lillehoj, Peter B

2015-08-01

Paper-based electrochemical biosensors are a promising technology that enables rapid, quantitative measurements on an inexpensive platform. However, the control of liquids in paper networks is generally limited to a single sample delivery step. Here, we propose a simple method to automate the loading and delivery of liquid samples to sensing electrodes on paper networks by stacking multiple layers of paper. Using these stacked paper devices (SPDs), we demonstrate a unique strategy to fully immerse planar electrodes by aqueous liquids via capillary flow. Amperometric measurements of xanthine oxidase revealed that electrochemical sensors on four-layer SPDs generated detection signals up to 75% higher compared with those on single-layer paper devices. Furthermore, measurements could be performed with minimal user involvement and completed within 30 min. Due to its simplicity, enhanced automation, and capability for quantitative measurements, stacked paper electrochemical biosensors can be useful tools for point-of-care testing in resource-limited settings. © 2015 Society for Laboratory Automation and Screening.

Polycyclic Aromatic Hydrocarbons in Electrocautery Smoke during Peritonectomy Procedures

PubMed Central

Näslund Andréasson, Sara; Mahteme, Haile; Sahlberg, Bo; Anundi, Helena

2012-01-01

Objective. This study identified and quantified polycyclic aromatic hydrocarbons (PAHs) in electrocautery smoke during 40 peritonectomy procedures and investigated any correlations and/or differences between levels of PAHs and perioperative variables. Methods. PAHs were measured in personal and stationary sampling by 40 mm Millipore cassettes, for adsorption of both gaseous and particle-bound PAHs. Results. All 16 USEPA priority pollutant PAHs were detected during peritonectomy procedures, naphthalene being the most abundant. For the only two PAHs with Swedish occupational exposure limits (OELs), benzo[a]pyrene and naphthalene, limits were never exceeded. Amount of bleeding was the only perioperative variable that correlated with levels of PAHs. Conclusions. Low levels of PAHs were detected in electrocautery smoke during peritonectomy procedures, and an increased amount of bleeding correlated with higher levels of PAHs. For evaluation of long-term health effects, more studies are needed. PMID:22685482

Molecularly imprinted covalent organic polymers for the selective extraction of benzoxazole fluorescent whitening agents from food samples.

PubMed

Ding, Hui; Wang, Rongyu; Wang, Xiao; Ji, Wenhua

2018-06-21

Molecularly imprinted covalent organic polymers were constructed by an imine-linking reaction between 1,3,5-triformylphloroglucinol and 2,6-diaminopyridine and used for the selective solid-phase extraction of benzoxazole fluorescent whitening agents from food samples. Binding experiments showed that imprinting sites on molecularly imprinted polymers had higher selectivity for targets compared with those of the corresponding non-imprinted polymers. Parameters affecting the solid-phase extraction procedure were examined. Under optimal conditions, actual samples were treated and the eluent was analyzed with high-performance liquid chromatography with diode-array detection. The results showed that the established method owned the wide linearity, satisfactory detection limits and quantification limits, and acceptable recoveries. Thus, this developed method possesses the practical potential to the selectively determine benzoxazole fluorescent whitening agents in complex food samples. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

High contrast sensitivity for visually guided flight control in bumblebees.

PubMed

Chakravarthi, Aravin; Kelber, Almut; Baird, Emily; Dacke, Marie

2017-12-01

Many insects rely on vision to find food, to return to their nest and to carefully control their flight between these two locations. The amount of information available to support these tasks is, in part, dictated by the spatial resolution and contrast sensitivity of their visual systems. Here, we investigate the absolute limits of these visual properties for visually guided position and speed control in Bombus terrestris. Our results indicate that the limit of spatial vision in the translational motion detection system of B. terrestris lies at 0.21 cycles deg -1 with a peak contrast sensitivity of at least 33. In the perspective of earlier findings, these results indicate that bumblebees have higher contrast sensitivity in the motion detection system underlying position control than in their object discrimination system. This suggests that bumblebees, and most likely also other insects, have different visual thresholds depending on the behavioral context.

Determination of trace quaternary ammonium surfactants in water by combining solid-phase extraction with surface-assisted laser desorption/ionization mass spectrometry.

PubMed

Chen, Y C; Sun, M C

2001-01-01

This study demonstrates the feasibility of combining solid-phase extraction (SPE) with surface-assisted laser desorption/ionization (SALDI) mass spectrometry to determine trace quaternary ammonium surfactants in water. The trace surfactants in water were directly concentrated on the surface of activated carbon sorbent in SPE. The activated carbon sorbent was then mixed with the SALDI liquid for SALDI analysis. No SPE elution procedure was necessary. Experimental results indicate that the surfactants with longer chain alkyl groups exhibit higher sensitivities than those with shorter chain alkyl groups in SPE-SALDI analysis. The detection limit for hexadecyltrimethylammonium bromide is around 10 ppt in SPE-SALDI analysis by sampling 100 mL of aqueous solution, while that of tetradecyltrimethylammonium bromide is about 100 ppt. The detection limit for decyltrimethylammonium bromide and dodecyltrimethylammonium bromide is in the low-ppb range. Copyright 2001 John Wiley & Sons, Ltd.

Electrochemical biosensing of galactose based on carbon materials: graphene versus multi-walled carbon nanotubes.

PubMed

Dalkıran, Berna; Erden, Pınar Esra; Kılıç, Esma

2016-06-01

In this study, two enzyme electrodes based on graphene (GR), Co3O4 nanoparticles and chitosan (CS) or multi-walled carbon nanotubes (MWCNTs), Co3O4 nanoparticles, and CS, were fabricated as novel biosensing platforms for galactose determination, and their performances were compared. Galactose oxidase (GaOx) was immobilized onto the electrode surfaces by crosslinking with glutaraldehyde. Optimum working conditions of the biosensors were investigated and the analytical performance of the biosensors was compared with respect to detection limit, linearity, repeatability, and stability. The MWCNTs-based galactose biosensor provided about 1.6-fold higher sensitivity than its graphene counterpart. Moreover, the linear working range and detection limit of the MWCNTs-based galactose biosensor was superior to the graphene-modified biosensor. The successful application of the purposed biosensors for galactose biosensing in human serum samples was also investigated.

Industrial-hygiene characterization of ethylene oxide exposures of hospital and nursing-home workers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ringenburg, V.L.; Elliott, L.J.; Morelli-Schroth, P.

Industrial-hygiene surveys were conducted at 12 hospitals and one nursing home to determine possible employee exposure to ethylene oxide (EtO). Different types of exposure situations existed at each of the facilities as a result of various engineering controls, administrative controls and work practices. Sampling indicated that the time-weighted averages (TWAs) of exposure over periods of 36 to 724 minutes ranged from below the limit of detection to 6.7 parts per million (ppm). Personal short-term exposure levels covering 2 to 30 minutes ranged from less than the limit of detection to 103.2ppm. Factors found to be responsible for these higher-than-permissible levelsmore » of EtO exposure included improper installation or lack of engineering controls (such as improper placement of the sterilizing operations), unbalanced ventilation systems, and lack of administrative controls resulting in inappropriate work practices.« less

The upper values of plasma creatine kinase of professional soccer players during the Brazilian National Championship.

PubMed

Lazarim, Fernanda L; Antunes-Neto, Joaquim M F; da Silva, Fernando O C; Nunes, Lázaro A S; Bassini-Cameron, Adriana; Cameron, Luiz-Cláudio; Alves, Armindo A; Brenzikofer, René; de Macedo, Denise Vaz

2009-01-01

The current schedule of the Brazilian Soccer Championship may not give players enough recovery time between games. This could increase the chances of muscle damage and impaired performance. We hypothesized that plasma creatine kinase (CK) activity could be a reliable indirect marker of muscle overload in soccer players, so we sought to identify the reference values for upper limits of CK activity during a real-life elite competition. This study analyzed changes in plasma CK activity in 128 professional soccer players at different times during the Brazilian Championship. The upper limits of the 97.5th and 90th percentiles determined for CK activity were 1.338U/L and 975U/L, respectively, markedly higher than values previously reported in the literature. We also evaluated a team monthly throughout the Championship. The upper limit of the 90th percentile, 975U/L, was taken as the decision limit. Six players showing plasma CK values higher than this were asked to decrease their training for 1 week. These players presented lower CK values afterwards. Only one player with a CK value higher than the decision limit (1800U/L 1 day before a game) played on the field and was unfortunately injured during the game. The CK activity in all the other players showed a significant decrease over the course of the Championship, and the values became more homogeneous at the end. The results presented here suggest that plasma CK upper limit values can be used as a practical alternative for early detection of muscle overload in competing soccer players.

[Detection of occupational hazards in a large shipbuilding factory].

PubMed

Du, Weijia; Wang, Zhi; Zhang, Hai; Zhou, Liping; Huang, Minzhi; Liu, Yimin

2014-03-01

To provide evidence for the prevention and treatment of occupational diseases by the analysis of existing major occupational hazards and health conditions of workers in a large shipbuilding factory. Field investigation of occupational conditions was conducted to examine the existence of occupational hazards from 2009 to 2012 in a large shipbuilding factory, and then the results of physical examination among its workers were analyzed. Other than the metal dust (total dust), the levels of other dusts and manganese dioxide were beyond the national standard to various degrees, and through a sampling point detection, it was found that the levels of manganese dioxide exceeded the standard by 42.8%. The maximum time-weighted average concentration in individuals was 27.927 mg/m(3), much higher than the national standard limit. For harmful gas detection in individuals, xylene was 38.4%above the standard level (the highest concentration reached 1447.7 mg/m(3)); moreover, both toluene and ethylbenzene exceeded the national standard at different levels. Among the noise-exposed workers, 71%worked in the environment where the daily noise was above the limit of the national standard (85 dB). Physical examinations in 2010 and 2012 showed that the abnormal rate of audiometry in workers was higher than 15%. Dust (total dust), manganese dioxide, benzene, and noise are the main occupational hazards among the workers in the large shipbuilding factory, and strict protection and control for these hazards should be implemented for the workers in the factory.

Evaluation of two membrane-based microextraction techniques for the determination of endocrine disruptors in aqueous samples by HPLC with diode array detection.

PubMed

Luiz Oenning, Anderson; Lopes, Daniela; Neves Dias, Adriana; Merib, Josias; Carasek, Eduardo

2017-11-01

In this study, the viability of two membrane-based microextraction techniques for the determination of endocrine disruptors by high-performance liquid chromatography with diode array detection was evaluated: hollow fiber microporous membrane liquid-liquid extraction and hollow-fiber-supported dispersive liquid-liquid microextraction. The extraction efficiencies obtained for methylparaben, ethylparaben, bisphenol A, benzophenone, and 2-ethylhexyl-4-methoxycinnamate from aqueous matrices obtained using both approaches were compared and showed that hollow fiber microporous membrane liquid-liquid extraction exhibited higher extraction efficiency for most of the compounds studied. Therefore, a detailed optimization of the extraction procedure was carried out with this technique. The optimization of the extraction conditions and liquid desorption were performed by univariate analysis. The optimal conditions for the method were supported liquid membrane with 1-octanol for 10 s, sample pH 7, addition of 15% w/v of NaCl, extraction time of 30 min, and liquid desorption in 150 μL of acetonitrile/methanol (50:50 v/v) for 5 min. The linear correlation coefficients were higher than 0.9936. The limits of detection were 0.5-4.6 μg/L and the limits of quantification were 2-16 μg/L. The analyte relative recoveries were 67-116%, and the relative standard deviations were less than 15.5%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sandwich enzyme-linked immunosorbent assay for naringin.

PubMed

Qu, Huihua; Wang, Xueqian; Qu, Baoping; Kong, Hui; Zhang, Yue; Shan, Wenchao; Cheng, Jinjun; Wang, Qingguo; Zhao, Yan

2016-01-15

Among the currently used immunoassay techniques, sandwich ELISA exhibits higher specificity, lower cross-reactivity, and a wider working range compared to the corresponding competitive assays. However, it is difficult to obtain a pair of antibodies that can simultaneously bind to two epitopes of a molecule with a molecular weight of less than 1000 Da. Naringin (Nar) is a flavonoid with a molecular mass of 580 Da. The main aim of this study was to develop a sandwich ELISA for detecting Nar. Two hybridomas secreting anti-Nar monoclonal antibodies (mAbs) were produced by fusing splenocytes from a mouse immunised against Nar-bovine serum albumin (BSA) conjugated with a hypoxanthine-aminopterin-thymidine (HAT)-sensitive mouse myeloma cell line; a sandwich ELISA for detecting Nar was developed using these two well-characterised anti-Nar mAbs. The performance of the sandwich assay was further evaluated by limit of detection (LOD), limit of quantification (LOQ), recovery, and interference analyses. A dose-response curve to Nar was obtained with an LOD of 6.78 ng mL(-1) and an LOQ of 13.47 ng mL(-1). The inter-assay and intra-assay coefficients of variation were 4.32% and 7.48%, respectively. The recovery rate of Nar from concentrated Fructus aurantii granules was 83.63%. A high correlation was obtained between HPLC and sandwich ELISA. These results demonstrate that the sandwich ELISA method has higher specificity for Nar than indirect competitive ELISA. Copyright © 2015 Elsevier B.V. All rights reserved.

Droplet digital polymerase chain reaction (PCR) outperforms real-time PCR in the detection of environmental DNA from an invasive fish species.

PubMed

Doi, Hideyuki; Takahara, Teruhiko; Minamoto, Toshifumi; Matsuhashi, Saeko; Uchii, Kimiko; Yamanaka, Hiroki

2015-05-05

Environmental DNA (eDNA) has been used to investigate species distributions in aquatic ecosystems. Most of these studies use real-time polymerase chain reaction (PCR) to detect eDNA in water; however, PCR amplification is often inhibited by the presence of organic and inorganic matter. In droplet digital PCR (ddPCR), the sample is partitioned into thousands of nanoliter droplets, and PCR inhibition may be reduced by the detection of the end-point of PCR amplification in each droplet, independent of the amplification efficiency. In addition, real-time PCR reagents can affect PCR amplification and consequently alter detection rates. We compared the effectiveness of ddPCR and real-time PCR using two different PCR reagents for the detection of the eDNA from invasive bluegill sunfish, Lepomis macrochirus, in ponds. We found that ddPCR had higher detection rates of bluegill eDNA in pond water than real-time PCR with either of the PCR reagents, especially at low DNA concentrations. Limits of DNA detection, which were tested by spiking the bluegill DNA to DNA extracts from the ponds containing natural inhibitors, found that ddPCR had higher detection rate than real-time PCR. Our results suggest that ddPCR is more resistant to the presence of PCR inhibitors in field samples than real-time PCR. Thus, ddPCR outperforms real-time PCR methods for detecting eDNA to document species distributions in natural habitats, especially in habitats with high concentrations of PCR inhibitors.

Multi-colored immunochromatography using nanobeads for rapid and sensitive typing of seasonal influenza viruses.

PubMed

Sakurai, Akira; Takayama, Katsuyoshi; Nomura, Namiko; Yamamoto, Naoki; Sakoda, Yoshihiro; Kobayashi, Yukuharu; Kida, Hiroshi; Shibasaki, Futoshi

2014-12-01

Immunochromatography (IC) is an antigen-detection assay that plays an important role in the rapid diagnosis of influenza viruses because of its rapid turnaround and ease of use. Despite the usefulness of IC, the limit of detection of common IC kits is as high as 10(3)-10(4) plaque forming units (pfu) per reaction, resulting in their limited sensitivities. Early diagnosis within 24h would provide more appropriate timing of treatment. In this study, a multi-colored NanoAct™ bead IC was established to detect seasonal influenza viruses. This method has approximately 10-fold higher sensitivity than that of colloidal gold or colored latex bead IC assays, and does not require specific instruments. More notably, NanoAct™ bead IC can distinguish influenza A and B viruses from clinical samples with a straightforward readout composed of colored lines. Our results will provide new strategies for the diagnosis, treatment, and a chance to survey of influenza viruses in developing countries and in the field research. Copyright © 2014 Elsevier B.V. All rights reserved.

Antibiotic use in heavy pigs: Comparison between urine and muscle samples from food chain animals analysed by HPLC-MS/MS.

PubMed

Chiesa, Luca Maria; Nobile, Maria; Panseri, Sara; Arioli, Francesco

2017-11-15

The antibiotic overuse in zoothechnics, due to prophylactic and therapeutic treatments, or to their growth-promoting activity, is a major cause for the onset of widespread antibiotic resistance. Of particular relevance to this study, is the antibiotic abuse in pig breeding. Despite the comprehensive literature on residue controls in pig muscle, data on pig urine, a non-invasive, on-farm collectable matrix, are lacking. Therefore, we validated an HPLC-MS/MS method to detect 29 antimicrobials from eight classes and applied it to 43 anonymous pig urine and muscle paired samples and fulfilled the parameters in agreement with the Commission Decision 2002/657/UE. The analytical limits were moreover much lower than the maximum residue limits (MRLs) required by the Commission Regulation 37/2010/UE. In the samples, antibiotics were usually detected at higher frequencies and concentrations in urine than muscle. Urine proved a useful tool to detect antibiotic administration and their excessive use in pig farming is depicted. Copyright © 2017. Published by Elsevier Ltd.

Characterizing nonconstant instrumental variance in emerging miniaturized analytical techniques.

PubMed

Noblitt, Scott D; Berg, Kathleen E; Cate, David M; Henry, Charles S

2016-04-07

Measurement variance is a crucial aspect of quantitative chemical analysis. Variance directly affects important analytical figures of merit, including detection limit, quantitation limit, and confidence intervals. Most reported analyses for emerging analytical techniques implicitly assume constant variance (homoskedasticity) by using unweighted regression calibrations. Despite the assumption of constant variance, it is known that most instruments exhibit heteroskedasticity, where variance changes with signal intensity. Ignoring nonconstant variance results in suboptimal calibrations, invalid uncertainty estimates, and incorrect detection limits. Three techniques where homoskedasticity is often assumed were covered in this work to evaluate if heteroskedasticity had a significant quantitative impact-naked-eye, distance-based detection using paper-based analytical devices (PADs), cathodic stripping voltammetry (CSV) with disposable carbon-ink electrode devices, and microchip electrophoresis (MCE) with conductivity detection. Despite these techniques representing a wide range of chemistries and precision, heteroskedastic behavior was confirmed for each. The general variance forms were analyzed, and recommendations for accounting for nonconstant variance discussed. Monte Carlo simulations of instrument responses were performed to quantify the benefits of weighted regression, and the sensitivity to uncertainty in the variance function was tested. Results show that heteroskedasticity should be considered during development of new techniques; even moderate uncertainty (30%) in the variance function still results in weighted regression outperforming unweighted regressions. We recommend utilizing the power model of variance because it is easy to apply, requires little additional experimentation, and produces higher-precision results and more reliable uncertainty estimates than assuming homoskedasticity. Copyright © 2016 Elsevier B.V. All rights reserved.

Glyphosate in Irish adults - A pilot study in 2017.

PubMed

Connolly, Alison; Leahy, Michelle; Jones, Kate; Kenny, Laura; Coggins, Marie A

2018-08-01

Glyphosate is the highest volume herbicide used globally and has recently been classified as a 2 A 'probably carcinogenic to humans' by the International Agency for Research on Cancer (IARC). There is limited data to evaluate the public health impacts from glyphosate exposure. The objective of this study is to conduct an exploratory glyphosate exposure assessment study among Irish adults, who were non-occupational users of glyphosate. A convenient sampling method was used, collecting one first morning void spot urine sample from each participant. A biomonitoring survey involving the collection and analysis of 20 ml spot urine samples from 50 Irish adults was conducted in June 2017. Participants completed a short questionnaire to collect information on demographics, dietary habits and lifestyle. Glyphosate was extracted using solid phase extraction (SPE) and analysed by liquid chromatography tandem mass spectrometry (LC-MC/MS). Of the 50 urine samples analysed, 10 (20%) contained detectable levels of glyphosate (0.80-1.35 µg L -1 ). Exposure concentrations are higher than those reported in comparable studies of European and American adults. Glyphosate was detectable in 20% of the samples collected from Irish adults. The low proportion of detectable glyphosate levels could be due to lower localised use of pesticides, having a small sample size or the higher analytical detection limit used in this study (0.5 µg L -1 ), which could underestimate the true exposure and warrants further investigation. Given the widespread use of glyphosate, further information on population exposure is required to advance our understanding of the relationship between chronic low dose exposure to glyphosate and human health risk. Copyright © 2018 Elsevier Inc. All rights reserved.

Detection of Citrus tristeza virus by using fluorescence resonance energy transfer-based biosensor

NASA Astrophysics Data System (ADS)

Shojaei, Taha Roodbar; Salleh, Mohamad Amran Mohd; Sijam, Kamaruzaman; Rahim, Raha Abdul; Mohsenifar, Afshin; Safarnejad, Reza; Tabatabaei, Meisam

2016-12-01

Due to the low titer or uneven distribution of Citrus tristeza virus (CTV) in field samples, detection of CTV by using conventional detection techniques may be difficult. Therefore, in the present work, the cadmium-telluride quantum dots (QDs) was conjugated with a specific antibody against coat protein (CP) of CTV, and the CP were immobilized on the surface of gold nanoparticles (AuNPs) to develop a specific and sensitive fluorescence resonance energy transfer (FRET)-based nanobiosensor for detecting CTV. The maximum FRET efficiency for the developed nano-biosensor was observed at 60% in AuNPs-CP/QDs-Ab ratio of 1:8.5. The designed system showed higher sensitivity and specificity over enzyme linked immunosorbent assay (ELISA) with a limit of detection of 0.13 μg mL- 1 and 93% and 94% sensitivity and specificity, respectively. As designed sensor is rapid, sensitive, specific and efficient in detecting CTV, this could be envisioned for diagnostic applications, surveillance and plant certification program.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of 86 volatile organic compounds in water by gas chromatography/mass spectrometry, including detections less than reporting limits

USGS Publications Warehouse

Connor, Brooke F.; Rose, Donna L.; Noriega, Mary C.; Murtaugh, Lucinda K.; Abney, Sonja R.

1998-01-01

This report presents precision and accuracy data for volatile organic compounds (VOCs) in the nanogram-per-liter range, including aromatic hydrocarbons, reformulated fuel components, and halogenated hydrocarbons using purge and trap capillary-column gas chromatography/mass spectrometry. One-hundred-four VOCs were initially tested. Of these, 86 are suitable for determination by this method. Selected data are provided for the 18 VOCs that were not included. This method also allows for the reporting of semiquantitative results for tentatively identified VOCs not included in the list of method compounds. Method detection limits, method performance data, preservation study results, and blank results are presented. The authors describe a procedure for reporting low-concentration detections at less than the reporting limit. The nondetection value (NDV) is introduced as a statistically defined reporting limit designed to limit false positives and false negatives to less than 1 percent. Nondetections of method compounds are reported as ?less than NDV.? Positive detections measured at less than NDV are reported as estimated concentrations to alert the data user to decreased confidence in accurate quantitation. Instructions are provided for analysts to report data at less than the reporting limits. This method can support the use of either method reporting limits that censor detections at lower concentrations or the use of NDVs as reporting limits. The data-reporting strategy for providing analytical results at less than the reporting limit is a result of the increased need to identify the presence or absence of environmental contaminants in water samples at increasingly lower concentrations. Long-term method detection limits (LTMDLs) for 86 selected compounds range from 0.013 to 2.452 micrograms per liter (?g/L) and differ from standard method detection limits (MDLs) in that the LTMDLs include the long-term variance of multiple instruments, multiple operators, and multiple calibrations over a longer time. For these reasons, LTMDLs are expected to be slightly higher than standard MDLs. Recoveries for all of the VOCs tested ranged from 36 (tert-butyl formate) to 155 percent (pentachlorobenzene). The majority of the compounds ranged from 85 to 115 percent recovery and had less than 5 percent relative standard deviation for concentrations spiked between 1 to 500 ?g/L in volatile blank-, surface-, and ground-water samples. Recoveries of 60 set spikes at low concentrations ranged from 70 to 114 percent (1,2,3- trimethylbenzene and acetone). Recovery data were collected over 6 months with multiple instruments, operators, and calibrations. In this method, volatile organic compounds are extracted from a water sample by actively purging with helium. The VOCs are collected onto a sorbent trap, thermally desorbed, separated by a Megabore gas chromatographic capillary column, and finally determined by a full-scan quadrupole mass spectrometer. Compound identification is confirmed by the gas chromatographic retention time and by the resultant mass spectrum, typically identified by three unique ions. An unknown compound detected in a sample can be tentatively identified by comparing the unknown mass spectrum to reference spectra in the mass-spectra computer-data system library compiled by the National Institute of Standards and Technology.

Image Change Detection via Ensemble Learning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Benjamin W; Vatsavai, Raju

2013-01-01

The concept of geographic change detection is relevant in many areas. Changes in geography can reveal much information about a particular location. For example, analysis of changes in geography can identify regions of population growth, change in land use, and potential environmental disturbance. A common way to perform change detection is to use a simple method such as differencing to detect regions of change. Though these techniques are simple, often the application of these techniques is very limited. Recently, use of machine learning methods such as neural networks for change detection has been explored with great success. In this work,more » we explore the use of ensemble learning methodologies for detecting changes in bitemporal synthetic aperture radar (SAR) images. Ensemble learning uses a collection of weak machine learning classifiers to create a stronger classifier which has higher accuracy than the individual classifiers in the ensemble. The strength of the ensemble lies in the fact that the individual classifiers in the ensemble create a mixture of experts in which the final classification made by the ensemble classifier is calculated from the outputs of the individual classifiers. Our methodology leverages this aspect of ensemble learning by training collections of weak decision tree based classifiers to identify regions of change in SAR images collected of a region in the Staten Island, New York area during Hurricane Sandy. Preliminary studies show that the ensemble method has approximately 11.5% higher change detection accuracy than an individual classifier.« less

Development of new solid-phase microextraction fibers by sol-gel technology for the determination of organophosphorus pesticide multiresidues in food.

PubMed

Yu, Jianxin; Wu, Caiying; Xing, Jun

2004-05-21

Allyloxy bisbenzo 16-crown-5 trimethoxysilane was first used as precursor to prepare the sol-gel-derived bisbenzo crown ether/hydroxyl-terminated silicone oil (OH-TSO) SPME coating. The coating procedure involving sol solution composition and conditioning process was presented. Compared with commercial SPME stationary phases, the new coatings showed higher extraction efficiency and therefore could provide higher sensitivity for organphosphorous pesticides (OPs). Limits of detection (LODs) were in the range of 0.003-1.0 ng/g for these OPs in food samples (honey, juice, orange and pakchoi). The optimal extraction conditions of the new coatings to OPs in these samples were investigated by adjusting extraction time, salt addition, extraction temperature, and dilution ratios of samples with distilled water by using SPME coupled with gas chromatography (GC)-flame photometric detection (FPD). The method was applied to determine the concentrations of OPs in real samples.

40 CFR Appendix B to Part 136 - Definition and Procedure for the Determination of the Method Detection Limit-Revision 1.11

Code of Federal Regulations, 2010 CFR

2010-07-01

... calculated method detection limit. To insure that the estimate of the method detection limit is a good...) where: MDL = the method detection limit t(n-1,1- α=.99) = the students' t value appropriate for a 99... Determination of the Method Detection Limit-Revision 1.11 B Appendix B to Part 136 Protection of Environment...

Material limitations on the detection limit in refractometry.

PubMed

Skafte-Pedersen, Peder; Nunes, Pedro S; Xiao, Sanshui; Mortensen, Niels Asger

2009-01-01

We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η, with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a bio-liquid environment, such as a water buffer. In the transparency window (λ ≳ 1100 nm) of silicon the detection limit becomes almost independent on the filling fraction, while in the visible, the detection limit depends strongly on the filling fraction because the silicon absorbs strongly.

Occurrence, distribution and transport of pesticides into the Salton Sea Basin, California, 2001-2002

USGS Publications Warehouse

LeBlanc, L.A.; Kuivila, K.M.

2008-01-01

The Salton Sea is a hypersaline lake located in southeastern California. Concerns over the ecological impacts of sediment quality and potential human exposure to dust emissions from exposed lakebed sediments resulting from anticipated shrinking of shoreline led to a study of pesticide distribution and transport within the Salton Sea Basin, California, in 2001-2002. Three sampling stations-upriver, river mouth, and offshore-were established along each of the three major rivers that discharge into the Salton Sea. Large-volume water samples were collected for analysis of pesticides in water and suspended sediments at the nine sampling stations. Samples of the bottom sediment were also collected at each site for pesticide analysis. Sampling occurred in October 2001, March-April 2002, and October 2002, coinciding with the regional fall and spring peaks in pesticide use in the heavily agricultural watershed. Fourteen current-use pesticides were detected in water and the majority of dissolved concentrations ranged from the limits of detection to 151 ng/l. Diazinon, EPTC and malathion were detected at much higher concentrations (940-3,830 ng/l) at the New and Alamo River upriver and near-shore stations. Concentrations of carbaryl, dacthal, diazinon, and EPTC were higher in the two fall sampling periods, whereas concentrations of atrazine, carbofuran, and trifluralin were higher during the spring, which matched seasonal use patterns of these pesticides. Current-use pesticides were also detected on suspended and bed sediments in concentrations ranging from detection limits to 106 ng/g. Chlorpyrifos, dacthal, EPTC, trifluralin, and DDE were the most frequently detected pesticides on sediments from all three rivers. The number of detections and concentrations of suspended sediment-associated pesticides were often similar for the river upriver and near-shore sites, consistent with downstream transport of pesticides via suspended sediment. While detectable suspended sediment pesticide concentrations were more sporadic than detected aqueous concentrations, seasonal trends were similar to those for dissolved concentrations. Generally, the pesticides detected on suspended sediments were the same as those on the bed sediments, and concentrations were similar, especially at the Alamo River upriver site. With a few exceptions, pesticides were not detected in suspended or bed sediments from the off-shore sites. The partitioning of pesticides between water and sediment was not predictable from solely the physical-chemical properties of individual pesticide compounds, but appear to be a complicated function of the quantity of pesticide applied in the watershed, residence time of sediments in the water, and compound solubility and hydrophobicity. Sediment concentrations of most pesticides were found to be 100-1,000 times lower than the low-effects levels determined in human health risk assessment studies. However, maximum concentrations of chlorpyrifos on suspended sediments were approximately half the low-effects level, suggesting the need for further sediment characterization of lake sediments proximate to riverine inputs. ?? 2008 Springer Science+Business Media B.V.

The effect of laser ablation parameters on optical limiting properties of silver nanoparticles

NASA Astrophysics Data System (ADS)

Gursoy, Irmak; Yaglioglu, Halime Gul

2017-09-01

This paper presents the effect of laser ablation parameters on optical limiting properties of silver nanoparticles. The current applications of lasers such as range finding, guidance, detection, illumination and designation have increased the potential of damaging optical imaging systems or eyes temporary or permanently. The applications of lasers introduce risks for sensors or eyes, when laser power is higher than damage threshold of the detection system. There are some ways to protect these systems such as neutral density (nd) filters, shutters, etc. However, these limiters reduce the total amount of light that gets into the system. Also, response time of these limiters may not be fast enough to prevent damage and cause precipitation in performance due to deprivation of transmission or contrast. Therefore, optical limiting filters are needed that is transparent for low laser intensities and limit or block the high laser intensities. Metal nanoparticles are good candidates for such optical limiting filters for ns pulsed lasers or CW lasers due to their high damage thresholds. In this study we investigated the optical limiting performances of silver nanoparticles produced by laser ablation technique. A high purity silver target immersed in pure water was ablated with a Nd:YAG nanosecond laser at 532 nm. The effect of altering laser power and ablation time on laser ablation efficiency of nanoparticles was investigated experimentally and optimum values were specified. Open aperture Zscan experiment was used to investigate the effect of laser ablation parameters on the optical limiting performances of silver nanoparticles in pure water. It was found that longer ablation time decreases the optical limiting threshold. These results are useful for silver nanoparticles solutions to obtain high performance optical limiters.

Analysis of the accuracy and precision of the McMaster method in detection of the eggs of Toxocara and Trichuris species (Nematoda) in dog faeces.

PubMed

Kochanowski, Maciej; Dabrowska, Joanna; Karamon, Jacek; Cencek, Tomasz; Osiński, Zbigniew

2013-07-01

The aim of this study was to determine the accuracy and precision of McMaster method with Raynaud's modification in the detection of the eggs of the nematodes Toxocara canis (Werner, 1782) and Trichuris ovis (Abildgaard, 1795) in faeces of dogs. Four variants of McMaster method were used for counting: in one grid, two grids, the whole McMaster chamber and flotation in the tube. One hundred sixty samples were prepared from dog faeces (20 repetitions for each egg quantity) containing 15, 25, 50, 100, 150, 200, 250 and 300 eggs of T. canis and T. ovis in 1 g of faeces. To compare the influence of kind of faeces on the results, samples of dog faeces were enriched at the same levels with the eggs of another nematode, Ascaris suum Goeze, 1782. In addition, 160 samples of pig faeces were prepared and enriched only with A. suum eggs in the same way. The highest limit of detection (the lowest level of eggs that were detected in at least 50% of repetitions) in all McMaster chamber variants were obtained for T. canis eggs (25-250 eggs/g faeces). In the variant with flotation in the tube, the highest limit of detection was obtained for T. ovis eggs (100 eggs/g). The best results of the limit of detection, sensitivity and the lowest coefficients of variation were obtained with the use of the whole McMaster chamber variant. There was no significant impact of properties of faeces on the obtained results. Multiplication factors for the whole chamber were calculated on the basis of the transformed equation of the regression line, illustrating the relationship between the number of detected eggs and that of the eggs added to the'sample. Multiplication factors calculated for T. canis and T. ovis eggs were higher than those expected using McMaster method with Raynaud modification.

Accumulation of steroid hormones in soil and its adjacent aquatic environment from a typical intensive vegetable cultivation of North China.

PubMed

Zhang, Feng-Song; Xie, Yun-Feng; Li, Xue-Wen; Wang, Dai-Yi; Yang, Lin-Sheng; Nie, Zhi-Qiang

2015-12-15

Steroid hormones released from manure agricultural application are a matter of global concern. The residual levels of steroid hormones were studied in a typical intensive vegetable cultivation area in northeast China, with a long history of heavy manure application. Seven steroids (estrone, 17α-estradiol, 17β-estradiol, estriol, testosterone, androstendione and progesterone) were analyzed from soil sampled from vegetable greenhouses, from sediments and water from the adjacent drainage ditch and from the groundwater. The results showed that target steroids were detected in the soil samples, with detection frequencies varying from 3.13 to 100%. The steroid concentrations varied substantially in soils, ranging from below the detection limit to 109.7μg·kg(-1). Three steroids-progesterone, androstendione and estrone-were found to have relatively high residue concentrations in soil, with maximum concentrations of 109.7, 9.83 and 13.30μg·kg(-1), respectively. In adjacent groundwater, all the steroids, with the exception of estrone, were detected in one or more of the 13 groundwater samples. The concentrations of steroids in groundwater ranged from below the method detection limit to 2.38ng·L(-1). Six of the seven (excluding androstendione) were detected in drainage ditch water samples, with concentrations ranging from below the detection limit to 14ng·L(-1). Progesterone, androstendione and estrone accumulated relatively easily in soils; their concentrations in groundwater were lower than those of other steroids. The concentrations of testosterone and estriol were relatively low in soil, while in groundwater were higher than those of other steroids. The residual levels of steroids in soil and groundwater showed a clear spatial variation in the study area. The residual levels of steroid hormones in soil varied substantially between differently planted greenhouses. Copyright © 2015. Published by Elsevier B.V.

Jet-induced star formation in 3C 285 and Minkowski's Object

NASA Astrophysics Data System (ADS)

Salomé, Q.; Salomé, P.; Combes, F.

2015-02-01

How efficiently star formation proceeds in galaxies is still an open question. Recent studies suggest that active galactic nucleus (AGN) can regulate the gas accretion and thus slow down star formation (negative feedback). However, evidence of AGN positive feedback has also been observed in a few radio galaxies (e.g. Centaurus A, Minkowski's Object, 3C 285, and the higher redshift 4C 41.17). Here we present CO observations of 3C 285 and Minkowski's Object, which are examples of jet-induced star formation. A spot (named 3C 285/09.6 in the present paper) aligned with the 3C 285 radio jet at a projected distance of ~70 kpc from the galaxy centre shows star formation that is detected in optical emission. Minkowski's Object is located along the jet of NGC 541 and also shows star formation. Knowing the distribution of molecular gas along the jets is a way to study the physical processes at play in the AGN interaction with the intergalactic medium. We observed CO lines in 3C 285, NGC 541, 3C 285/09.6, and Minkowski's Object with the IRAM 30 m telescope. In the central galaxies, the spectra present a double-horn profile, typical of a rotation pattern, from which we are able to estimate the molecular gas density profile of the galaxy. The molecular gas appears to be in a compact reservoir, which could be evidence of an early phase of the gas accretion after a recent merger event in 3C 285. No kinematic signature of a molecular outflow is detected by the 30 m telescope. Interestingly, 3C 285/09.6 and Minkowski's Object are not detected in CO. The cold gas mass upper limits are consistent with a star formation induced by the compression of dense ambient material by the jet. The depletion time scales in 3C 285/09.6 and Minkowski's Object are of the order of and even shorter than what is found in 3C 285, NGC 541, and local spiral galaxies (109 yr). The upper limit of the molecular gas surface density in 3C 285/09.6 at least follows a Schmidt-Kennicutt law if the emitting region is very compact, as suggested by the Hα emission, while Minkowski's Object is found to have a much higher star formation efficiency lower limit (very short depletion time). Higher sensitivity is necessary to detect CO in the star-forming spots, and higher spatial resolution is required to map the emission in these jet-induced star-forming regions. Based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

Driving under the influence of cocaine: Quantitative determination of basic drugs in oral fluid obtained during roadside controls and a controlled study with cocaine users.

PubMed

Di Fazio, Vincent; Wille, Sarah M R; Toennes, Stefan W; van Wel, Janelle H P; Ramaekers, Johannes G; Samyn, Nele

2018-03-10

Using the Belgian Drugs and Driving procedure, 36% of the cocaine-positive oral fluid (OF) screening results were not confirmed in plasma. This study investigates the impact of the choice of screening devices and confirmation matrix on the detection of cocaine use. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method quantifying cocaine, benzoylecgonine (BZE), and other basic drugs in OF was developed and validated. This method monitored OF samples obtained either from a roadside (n = 12) or a double-blind controlled study with cocaine users (n = 10) who were given either a capsule containing 300 mg of cocaine-HCl or a placebo. The OF data were compared to plasma concentrations to obtain concentration-time profiles. In addition, the sensitivity and accuracy of the Drugwipe5S® was assessed. A significant difference between the OF volume collected at baseline/placebo (median 0.93 mL [range 0.43-1.92 mL]) or after cocaine-HCL intake (0.79 mL [0.30-1.21 mL]) was observed. The median OF/Plasma at the 3 collection time points were 10.7, 13.8, 6.7 for cocaine and 0.8, 1.7, 0.8 for BZE, respectively. The Drugwipe5S® detected cocaine use until at least 4 hours after intake. When applying the Belgian legal confirmation decision limit of 10 ng/mL in OF, an accuracy of 75%-98% was observed, depending on the study setting. Cocaine concentrations in OF were much higher and were detected longer as compared to plasma, when applying the same decision limit. From a toxicological viewpoint, the longer detection window with the higher sensitivity of Cocaine and BZE is beneficial to detect drivers in the crash/fatigue phase. Copyright © 2018 John Wiley & Sons, Ltd.

Cost-effectiveness of point-of-care viral load monitoring of antiretroviral therapy in resource-limited settings: mathematical modelling study.

PubMed

Estill, Janne; Egger, Matthias; Blaser, Nello; Vizcaya, Luisa Salazar; Garone, Daniela; Wood, Robin; Campbell, Jennifer; Hallett, Timothy B; Keiser, Olivia

2013-06-01

Monitoring of HIV viral load in patients on combination antiretroviral therapy (ART) is not generally available in resource-limited settings. We examined the cost-effectiveness of qualitative point-of-care viral load tests (POC-VL) in sub-Saharan Africa. Mathematical model based on longitudinal data from the Gugulethu and Khayelitsha township ART programmes in Cape Town, South Africa. Cohorts of patients on ART monitored by POC-VL, CD4 cell count or clinically were simulated. Scenario A considered the more accurate detection of treatment failure with POC-VL only, and scenario B also considered the effect on HIV transmission. Scenario C further assumed that the risk of virologic failure is halved with POC-VL due to improved adherence. We estimated the change in costs per quality-adjusted life-year gained (incremental cost-effectiveness ratios, ICERs) of POC-VL compared with CD4 and clinical monitoring. POC-VL tests with detection limits less than 1000 copies/ml increased costs due to unnecessary switches to second-line ART, without improving survival. Assuming POC-VL unit costs between US$5 and US$20 and detection limits between 1000 and 10,000 copies/ml, the ICER of POC-VL was US$4010-US$9230 compared with clinical and US$5960-US$25540 compared with CD4 cell count monitoring. In Scenario B, the corresponding ICERs were US$2450-US$5830 and US$2230-US$10380. In Scenario C, the ICER ranged between US$960 and US$2500 compared with clinical monitoring and between cost-saving and US$2460 compared with CD4 monitoring. The cost-effectiveness of POC-VL for monitoring ART is improved by a higher detection limit, by taking the reduction in new HIV infections into account and assuming that failure of first-line ART is reduced due to targeted adherence counselling.

Detection of pH and Enzyme-Free H2O2 Sensing Mechanism by Using GdO x Membrane in Electrolyte-Insulator-Semiconductor Structure.

PubMed

Kumar, Pankaj; Maikap, Siddheswar; Qiu, Jian-Tai; Jana, Surajit; Roy, Anisha; Singh, Kanishk; Cheng, Hsin-Ming; Chang, Mu-Tung; Mahapatra, Rajat; Chiu, Hsien-Chin; Yang, Jer-Ren

2016-12-01

A 15-nm-thick GdO x membrane in an electrolyte-insulator-semiconductor (EIS) structure shows a higher pH sensitivity of 54.2 mV/pH and enzyme-free hydrogen peroxide (H2O2) detection than those of the bare SiO2 and 3-nm-thick GdO x membranes for the first time. Polycrystalline grain and higher Gd content of the thicker GdO x films are confirmed by transmission electron microscopy (TEM) and X-ray photo-electron spectroscopy (XPS), respectively. In a thicker GdO x membrane, polycrystalline grain has lower energy gap and Gd(2+) oxidation states lead to change Gd(3+) states in the presence of H2O2, which are confirmed by electron energy loss spectroscopy (EELS). The oxidation/reduction (redox) properties of thicker GdO x membrane with higher Gd content are responsible for detecting H2O2 whereas both bare SiO2 and thinner GdO x membranes do not show sensing. A low detection limit of 1 μM is obtained due to strong catalytic activity of Gd. The reference voltage shift increases with increase of the H2O2 concentration from 1 to 200 μM owing to more generation of Gd(3+) ions, and the H2O2 sensing mechanism has been explained as well.

Widespread Environmental Contamination with Mycobacterium tuberculosis Complex Revealed by a Molecular Detection Protocol

PubMed Central

Santos, Nuno; Santos, Catarina; Valente, Teresa; Gortázar, Christian; Almeida, Virgílio; Correia-Neves, Margarida

2015-01-01

Environmental contamination with Mycobacterium tuberculosis complex (MTC) has been considered crucial for bovine tuberculosis persistence in multi-host-pathogen systems. However, MTC contamination has been difficult to detect due to methodological issues. In an attempt to overcome this limitation we developed an improved protocol for the detection of MTC DNA. MTC DNA concentration was estimated by the Most Probable Number (MPN) method. Making use of this protocol we showed that MTC contamination is widespread in different types of environmental samples from the Iberian Peninsula, which supports indirect transmission as a contributing mechanism for the maintenance of bovine tuberculosis in this multi-host-pathogen system. The proportion of MTC DNA positive samples was higher in the bovine tuberculosis-infected than in presumed negative area (0.32 and 0.18, respectively). Detection varied with the type of environmental sample and was more frequent in sediment from dams and less frequent in water also from dams (0.22 and 0.05, respectively). The proportion of MTC-positive samples was significantly higher in spring (p<0.001), but MTC DNA concentration per sample was higher in autumn and lower in summer. The average MTC DNA concentration in positive samples was 0.82 MPN/g (CI95 0.70–0.98 MPN/g). We were further able to amplify a DNA sequence specific of Mycobacterium bovis/caprae in 4 environmental samples from the bTB-infected area. PMID:26561038

Multifunctional Hyperbolic Nanogroove Metasurface for Submolecular Detection.

PubMed

Jiang, Li; Zeng, Shuwen; Xu, Zhengji; Ouyang, Qingling; Zhang, Dao-Hua; Chong, Peter Han Joo; Coquet, Philippe; He, Sailing; Yong, Ken-Tye

2017-08-01

Metasurface serves as a promising plasmonic sensing platform for engineering the enhanced light-matter interactions. Here, a hyperbolic metasurface with the nanogroove structure in the subwavelength scale is designed. This metasurface is able to modify the wavefront and wavelength of surface plasmon wave with the variation of the nanogroove width or periodicity. At the specific optical frequency, surface plasmon polaritons are tightly confined and propagated with a diffraction-free feature due to the epsilon-near-zero effect. Most importantly, the groove hyperbolic metasurface can enhance the plasmonic sensing with an ultrahigh phase sensitivity of 30 373 deg RIU -1 and Goos-Hänchen shift sensitivity of 10.134 mm RIU -1 . The detection resolution for refractive index change of glycerol solution is achieved as 10 -8 RIU based on the phase measurement. The detection limit of bovine serum albumin (BSA) molecule is measured as low as 0.1 × 10 -18 m (1 × 10 -19 mol L -1 ), which corresponds to a submolecular detection level (0.13 BSA mm -2 ). As for low-weight biotin molecule, the detection limit is estimated below 1 × 10 -15 m (1 × 10 -15 mol L -1 , 1300 biotin mm -2 ). This enhanced plasmonic sensing performance is two orders of magnitude higher than those with current state-of-art plasmonic metamaterials and metasurfaces. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Empirical evaluation demonstrated importance of validating biomarkers for early detection of cancer in screening settings to limit the number of false-positive findings.

PubMed

Chen, Hongda; Knebel, Phillip; Brenner, Hermann

2016-07-01

Search for biomarkers for early detection of cancer is a very active area of research, but most studies are done in clinical rather than screening settings. We aimed to empirically evaluate the role of study setting for early detection marker identification and validation. A panel of 92 candidate cancer protein markers was measured in 35 clinically identified colorectal cancer patients and 35 colorectal cancer patients identified at screening colonoscopy. For each case group, we selected 38 controls without colorectal neoplasms at screening colonoscopy. Single-, two- and three-marker combinations discriminating cases and controls were identified in each setting and subsequently validated in the alternative setting. In all scenarios, a higher number of predictive biomarkers were initially detected in the clinical setting, but a substantially lower proportion of identified biomarkers could subsequently be confirmed in the screening setting. Confirmation rates were 50.0%, 84.5%, and 74.2% for one-, two-, and three-marker algorithms identified in the screening setting and were 42.9%, 18.6%, and 25.7% for algorithms identified in the clinical setting. Validation of early detection markers of cancer in a true screening setting is important to limit the number of false-positive findings. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

High-Performance Visible-Blind UV Phototransistors Based on n-Type Naphthalene Diimide Nanomaterials.

PubMed

Song, Inho; Lee, Seung-Chul; Shang, Xiaobo; Ahn, Jaeyong; Jung, Hoon-Joo; Jeong, Chan-Uk; Kim, Sang-Wook; Yoon, Woojin; Yun, Hoseop; Kwon, O-Pil; Oh, Joon Hak

2018-04-11

This study investigates the performance of single-crystalline nanomaterials of wide-band gap naphthalene diimide (NDI) derivatives with methylene-bridged aromatic side chains. Such materials are found to be easily used as high-performance, visible-blind near-UV light detectors. NDI single-crystalline nanoribbons are assembled using a simple solution-based process (without solvent-inclusion problems), which is then applied to organic phototransistors (OPTs). Such OPTs exhibit excellent n-channel transistor characteristics, including an average electron mobility of 1.7 cm 2 V -1 s -1 , sensitive UV detection properties with a detection limit of ∼1 μW cm -2 , millisecond-level responses, and detectivity as high as 10 15 Jones, demonstrating the highly sensitive organic visible-blind UV detectors. The high performance of our OPTs originates from the large face-to-face π-π stacking area between the NDI semiconducting cores, which is facilitated by methylene-bridged aromatic side chains. Interestingly, NDI-based nanoribbon OPTs exhibit a distinct visible-blind near-UV detection with an identical detection limit, even under intense visible light illumination (for example, 10 4 times higher intensity than UV light intensity). Our findings demonstrate that wide-band gap NDI-based nanomaterials are highly promising for developing high-performance visible-blind UV photodetectors. Such photodetectors could potentially be used for various applications including environmental and health-monitoring systems.

Material Limitations on the Detection Limit in Refractometry

PubMed Central

Skafte-Pedersen, Peder; Nunes, Pedro S.; Xiao, Sanshui; Mortensen, Niels Asger

2009-01-01

We discuss the detection limit for refractometric sensors relying on high-Q optical cavities and show that the ultimate classical detection limit is given by min {Δn} ≳ η, with n + iη being the complex refractive index of the material under refractometric investigation. Taking finite Q factors and filling fractions into account, the detection limit declines. As an example we discuss the fundamental limits of silicon-based high-Q resonators, such as photonic crystal resonators, for sensing in a bio-liquid environment, such as a water buffer. In the transparency window (λ ≳ 1100 nm) of silicon the detection limit becomes almost independent on the filling fraction, while in the visible, the detection limit depends strongly on the filling fraction because the silicon absorbs strongly. PMID:22291513

Detection of early stage prostate cancer by using a simple carbon nanotube@paper biosensor.

PubMed

Ji, Sungkyung; Lee, Myeongsoon; Kim, Don

2018-04-15

This study is an investigation for an inexpensive, simple and sensitive biosensor to detect prostate cancer using bioactivated-multi wall carbon nanotubes (MWCNTs, diameter of 20nm, length of 5µm) and a micro-pore filter paper (pore size of 0.45µm). For the immunoassay of prostate specific antigen (PSA), which is a biomarker of prostate cancer, MWCNTs were activated with PSA antibody (monoclonal antibody of the prostate specific antigen) by using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide sodium salt (NHSS). The activated MWCNTs were deposited on the micro-pore filter paper to use as a biosensor. The prepared biosensor can assay from 0 to 500ng/mL of PSA level within 2h with the detection limit of 1.18ng/mL by the measurement of resistance change. The resistance change was caused by site selective interaction between PSA and PSA-antigen with an inexpensive bench top digital multimeter (5 1/2 digits). The detection range and sensitivity of the prepared sensor are good enough to diagnose the early stage of prostate cancer (> 4ng/mL of PSA). This paper-based biosensor is about 20 times cheaper (fabricated biosensor price: 2.4 $) and over 10 times faster than enzyme-linked immunosorbent assay (ELISA), which is a general method for the detection of a specific protein in the modernized hospitals. Furthermore, the maximum detection limit is about 50 times higher than ELISA. Copyright © 2017 Elsevier B.V. All rights reserved.

Detection of influenza A virus from live-bird market poultry swab samples in China by a pan-IAV, one-step reverse-transcription FRET-PCR.

PubMed

Luan, Lu; Sun, Zhihao; Kaltenboeck, Bernhard; Huang, Ke; Li, Min; Peng, Daxin; Xu, Xiulong; Ye, Jianqiang; Li, Jing; Guo, Weina; Wang, Chengming

2016-07-22

The persistent public health threat of animal to human transmission of influenza A virus (IAV) has stimulated interest in rapid and accurate detection of all IAV subtypes in clinical specimens of animal origin. In this study, a new set of primers and probes was designed for one-step pan-IAV reverse-transcription fluorescence resonance energy transfer (FRET)-PCR. The detection limit of one-step pan-IAV RT FRET-PCR was 10 copies of the matrix gene per reaction, and proved to be equivalent or superior to virus isolation in detecting nine IAV subtypes. Application of the pan-IAV RT FRET-PCR to oral-pharyngeal and cloacal swab specimens collected from healthy poultry in 34 live bird markets in 24 provinces of China revealed that 9.2% of the animals (169/1,839) or 6.3% of their oral-pharyngeal or cloacal swabs (233/3,678) were positive for IAV, and 56.8% of IAV-positive samples were of the H9N2 subtype. Paralleling detection of IAV in H9N2-infected SPF chickens and chickens from LBM showed that pan-IAV FRET-PCR had a higher detection limit than virus isolation in eggs while the results by FRET-PCR and virus isolation overall matched. It is expected that this strategy can be useful for facile surveillance for IAV in clinical samples from a variety of sources.

Detection of influenza A virus from live-bird market poultry swab samples in China by a pan-IAV, one-step reverse-transcription FRET-PCR

PubMed Central

Luan, Lu; Sun, Zhihao; Kaltenboeck, Bernhard; Huang, Ke; Li, Min; Peng, Daxin; Xu, Xiulong; Ye, Jianqiang; Li, Jing; Guo, Weina; Wang, Chengming

2016-01-01

The persistent public health threat of animal to human transmission of influenza A virus (IAV) has stimulated interest in rapid and accurate detection of all IAV subtypes in clinical specimens of animal origin. In this study, a new set of primers and probes was designed for one-step pan-IAV reverse-transcription fluorescence resonance energy transfer (FRET)-PCR. The detection limit of one-step pan-IAV RT FRET-PCR was 10 copies of the matrix gene per reaction, and proved to be equivalent or superior to virus isolation in detecting nine IAV subtypes. Application of the pan-IAV RT FRET-PCR to oral-pharyngeal and cloacal swab specimens collected from healthy poultry in 34 live bird markets in 24 provinces of China revealed that 9.2% of the animals (169/1,839) or 6.3% of their oral-pharyngeal or cloacal swabs (233/3,678) were positive for IAV, and 56.8% of IAV-positive samples were of the H9N2 subtype. Paralleling detection of IAV in H9N2-infected SPF chickens and chickens from LBM showed that pan-IAV FRET-PCR had a higher detection limit than virus isolation in eggs while the results by FRET-PCR and virus isolation overall matched. It is expected that this strategy can be useful for facile surveillance for IAV in clinical samples from a variety of sources. PMID:27445010

Visual and Plasmon Resonance Absorption Sensor for Adenosine Triphosphate Based on the High Affinity between Phosphate and Zr(IV).

PubMed

Qi, Wenjing; Liu, Zhongyuan; Zhang, Wei; Halawa, Mohamed Ibrahim; Xu, Guobao

2016-10-12

Zr(IV) can form phosphate and Zr(IV) (-PO₃ 2- -Zr 4+ -) complex owing to the high affinity between Zr(IV) with phosphate. Zr(IV) can induce the aggregation of gold nanoparticles (AuNPs), while adenosine triphosphate(ATP) can prevent Zr(IV)-induced aggregation of AuNPs. Herein, a visual and plasmon resonance absorption (PRA)sensor for ATP have been developed using AuNPs based on the high affinity between Zr(IV)with ATP. AuNPs get aggregated in the presence of certain concentrations of Zr(IV). After the addition of ATP, ATP reacts with Zr(IV) and prevents AuNPs from aggregation, enabling the detection of ATP. Because of the fast interaction of ATP with Zr(IV), ATP can be detected with a detection limit of 0.5 μM within 2 min by the naked eye. Moreover, ATP can be detected by the PRA technique with higher sensitivity. The A 520nm / A 650nm values in PRA spectra increase linearly with the concentrations of ATP from 0.1 μM to 15 μM (r = 0.9945) with a detection limit of 28 nM. The proposed visual and PRA sensor exhibit good selectivity against adenosine, adenosine monophosphate, guanosine triphosphate, cytidine triphosphate and uridine triphosphate. The recoveries for the analysis of ATP in synthetic samples range from 95.3% to 102.0%. Therefore, the proposed novel sensor for ATP is promising for real-time or on-site detection of ATP.

Diazonium-based impedimetric aptasensor for the rapid label-free detection of Salmonella typhimurium in food sample.

PubMed

Bagheryan, Zahra; Raoof, Jahan-Bakhsh; Golabi, Mohsen; Turner, Anthony P F; Beni, Valerio

2016-06-15

Fast and accurate detection of microorganisms is of key importance in clinical analysis and in food and water quality monitoring. Salmonella typhimurium is responsible for about a third of all cases of foodborne diseases and consequently, its fast detection is of great importance for ensuring the safety of foodstuffs. We report the development of a label-free impedimetric aptamer-based biosensor for S. typhimurium detection. The aptamer biosensor was fabricated by grafting a diazonium-supporting layer onto screen-printed carbon electrodes (SPEs), via electrochemical or chemical approaches, followed by chemical immobilisation of aminated-aptamer. FTIR-ATR, contact angle and electrochemical measurements were used to monitor the fabrication process. Results showed that electrochemical immobilisation of the diazonium-grafting layer allowed the formation of a denser aptamer layer, which resulted in higher sensitivity. The developed aptamer-biosensor responded linearly, on a logarithm scale, over the concentration range 1 × 10(1) to 1 × 10(8)CFU mL(-1), with a limit of quantification (LOQ) of 1 × 10(1) CFU mL(-1) and a limit of detection (LOD) of 6 CFU mL(-1). Selectivity studies showed that the aptamer biosensor could discriminate S. typhimurium from 6 other model bacteria strains. Finally, recovery studies demonstrated its suitability for the detection of S. typhimurium in spiked (1 × 10(2), 1 × 10(4) and 1 × 10(6) CFU mL(-1)) apple juice samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Human exposure to metals: levels in autopsy tissues of individuals living near a hazardous waste incinerator.

PubMed

Mari, Montse; Nadal, Martí; Schuhmacher, Marta; Barbería, Eneko; García, Francisco; Domingo, José L

2014-06-01

The concentrations of a number of metals were determined in the brain, bone, kidney, liver, and lung of 20 autopsied subjects who had lived, at least 10 years, in the neighborhood of a hazardous waste incinerator (HWI) in Tarragona (Catalonia, Spain). Results were compared with those obtained in 1998 (baseline survey) and previous surveys (2003 and 2007). Arsenic, Be, Ni, Tl, and V showed concentrations below the corresponding detection limits in all tissues. Cadmium showed the highest levels in the kidney, with a mean value of 21.15 μg/g. However, Cd was found below the detection limit in the brain and bone. Chromium showed similar concentrations in the kidney, brain, and lung (range of mean values, 0.57-0.66 μg/g) and higher in the bone (1.38 μg/g). In turn, Hg was below the detection limit in all tissues with the exception of the kidney, where the mean concentration was 0.15 μg/g (range, <0.05-0.58 μg/g). On the other hand, Mn could be detected in all tissues showing the highest levels in the liver and kidney (1.45 and 1.09 μg/g, respectively). Moreover, Pb showed the highest concentrations in bone (mean, 1.39 μg/g; range, <0.025-4.88 μg/g). Finally, Sn could be detected only in some tissue samples, reaching the highest values in the bone (0.17 μg/g). The current metal levels in human tissues from individuals living near the HWI of Tarragona are comparable and of a similar magnitude to previously reported results corresponding to general populations, as well as those of our previous surveys.

Measurement and estimated health risks of semivolatile organic compounds (PCBs, PAHs, pesticides, and phthalates) in ambient air at the Hanford Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patton, G.W.; Cooper, A.T.; Blanton, M.L.

1997-09-01

Air samples for polychlorinated biphenyls (PCBs), chlorinated pesticides, phthalate plasticizers, and polycyclic aromatic hydrocarbons (PAHs) were collected at three Hanford Site locations (300-Area South Gate, southeast of 200-East Area, and a background location near Rattlesnake Springs). Samples were collected using high-volume air samplers equipped with a glass fiber filter and polyurethane foam plug sampling train. Target compounds were extracted from the sampling trains and analyzed using capillary gas chromatography with either electron capture detection or mass selective detection. Twenty of the 28 PCB congeners analyzed were found above the detection limits, with 8 of the congeners accounting for over 80%more » of the average PCB concentrations. The average sum of all individual PCB congeners ranged from 500-740 pg/m{sup 3}, with little apparent difference between the sampling locations. Twenty of the 25 pesticides analyzed were found above the detection limits, with endosulfan I, endosulfan II, and methoxychlor having the highest average concentrations. With the exception of the endosulfans, all other average pesticide concentrations were below 100 pg/m{sup 3}. There was little apparent difference between the air concentrations of pesticides measured at each location. Sixteen of the 18 PAHs analyzed were found above the detection limit. Phenanthrene, fluoranthene, pyrene, fluorene, chrysene, benzo(b)fluoranthene, and naphthalene were the only PAHs with average concentrations above 100 pg/m{sup 3}. Overall, the 300 Area had higher average PAH concentrations compared to the 200-East Area and the background location at Rattlesnake Springs; however, the air concentrations at the 300-Area also are influenced by sources on the Hanford Site and from nearby communities.« less

SEARCH FOR GAMMA RAY BURSTS WITH THE ARGO-YBJ DETECTOR IN SCALER MODE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aielli, G.; Camarri, P.; Bacci, C.

2009-07-10

We report on the search for gamma ray bursts (GRBs) in the energy range 1-100 GeV in coincidence with the prompt emission detected by satellites using the Astrophysical Radiation with Ground-based Observatory at YangBaJing (ARGO-YBJ) air shower detector. Thanks to its mountain location (Yangbajing, Tibet, People's Republic of China, 4300 m above sea level), active surface ({approx}6700 m{sup 2} of Resistive Plate Chambers), and large field of view ({approx}2 sr, limited only by the atmospheric absorption), the ARGO-YBJ air shower detector is particularly suitable for the detection of unpredictable and short duration events such as GRBs. The search is carriedmore » out using the 'single particle technique', i.e., counting all the particles hitting the detector without measurement of the energy and arrival direction of the primary gamma rays. Between 2004 December 17 and 2009 April 7, 81 GRBs detected by satellites occurred within the field of view of ARGO-YBJ (zenith angle {theta} {<=} 45 deg.). It was possible to examine 62 of these for >1 GeV counterpart in the ARGO-YBJ data finding no statistically significant emission. With a lack of detected spectra in this energy range fluence upper limits are profitable, especially when the redshift is known and the correction for the extragalactic absorption can be considered. The obtained fluence upper limits reach values as low as 10{sup -5} erg cm{sup -2} in the 1-100 GeV energy region. Besides this individual search for a higher energy counterpart, a statistical study of the stack of all the GRBs both in time and in phase was made, looking for a common feature in the GRB high-energy emission. No significant signal has been detected.« less

Comments on the New Tesla Electromagnetics. Part I. Discrepancies in Present EM Theory,

DTIC Science & Technology

1982-01-01

reality. In this reality superluminal velocity, multiple universes, travel back and forth in time, higher dimensions, variation of all "fundamental...logic -- fitted to the photon interaction by vector light as the fundamental observation mechanism -- is incapable of describing or modeling this more...fundamental reality. Using scalar waves and scalar interactions as much subtler, far less limited * observation/detection mechanisms , we must have a

Mover Position Detection for PMTLM Based on Linear Hall Sensors through EKF Processing

PubMed Central

Yan, Leyang; Zhang, Hui; Ye, Peiqing

2017-01-01

Accurate mover position is vital for a permanent magnet tubular linear motor (PMTLM) control system. In this paper, two linear Hall sensors are utilized to detect the mover position. However, Hall sensor signals contain third-order harmonics, creating errors in mover position detection. To filter out the third-order harmonics, a signal processing method based on the extended Kalman filter (EKF) is presented. The limitation of conventional processing method is first analyzed, and then EKF is adopted to detect the mover position. In the EKF model, the amplitude of the fundamental component and the percentage of the harmonic component are taken as state variables, and they can be estimated based solely on the measured sensor signals. Then, the harmonic component can be calculated and eliminated. The proposed method has the advantages of faster convergence, better stability and higher accuracy. Finally, experimental results validate the effectiveness and superiority of the proposed method. PMID:28383505

Carbon Nanotube Biosensors for Space Molecule Detection and Clinical Molecular Diagnostics

NASA Technical Reports Server (NTRS)

Han, Jie

2001-01-01

Both space molecule detection and clinical molecule diagnostics need to develop ultra sensitive biosensors for detection of less than attomole molecules such as amino acids for DNA. However all the electrode sensor systems including those fabricated from the existing carbon nanotubes, have a background level of nA (nanoAmp). This has limited DNA or other molecule detection to nA level or molecules whose concentration is, much higher than attomole level. A program has been created by NASA and NCI (National Cancer Institute) to exploit the possibility of carbon nanotube based biosensors to solve this problem for both's interest. In this talk, I will present our effort on the evaluation and novel design of carbon nanotubes as electrode biosensors with strategies to minimize background currents while maximizing signal intensity.The fabrication of nanotube electrode arrays, immobilization of molecular probes on nanotube electrodes and in vitro biosensor testing will also be discussed.

Detection of adulterated commercial Spanish beeswax.

PubMed

Serra Bonvehi, J; Orantes Bermejo, F J

2012-05-01

The physical and chemical parameters (melting point and saponification number), and the fraction of hydrocarbons, monoesters, acids and alcohols have been determined in 90 samples of Spanish commercial beeswax from Apis mellifera L. The adulteration with paraffins of different melting point, cow tallow, stearic acid, and carnauba wax were determined by HTGC-FID/MS detection, and the research was focussed mainly on paraffins and microcrystallines waxes. In general, the added adulterant can be identified by the presence of non-naturally beeswax components, and by the differences of values of selected components between pure and adulterated beeswax. The detection limits were determined using pure and adulterated beeswax with different amounts of added waxes (5%, 10%, 20% and 30%). Percentages higher than 1-5% of each adulterant can be detected in the mixtures. Paraffin waxes were confirmed in 33 of the 90 samples analysed at concentrations between 5% and 30%. Copyright © 2011 Elsevier Ltd. All rights reserved.

Self-assembly of nitrogen-doped carbon nanoparticles: a new ratiometric UV-vis optical sensor for the highly sensitive and selective detection of Hg(2+) in aqueous solution.

PubMed

Ruan, Yudi; Wu, Lie; Jiang, Xiue

2016-05-23

Water-soluble nitrogen-doped carbon nanoparticles (N-CNPs) prepared by the one-step hydrothermal treatment of uric acid were found to show ratiometric changes in their UV-vis spectra due to Hg(2+)-mediated self-assembly. For the first time, such a property was developed into a UV-vis optical sensor for detecting Hg(2+) in aqueous solutions with high sensitively and selectively (detection limit = 1.4 nM). More importantly, this novel sensor exhibits a higher linear sensitivity over a wider concentration range compared with the fluorescence sensor based on the same N-CNPs. This work opens an exciting new avenue to explore the use of carbon nanoparticles in constructing UV-vis optical sensors for the detection of metal ions and the use of carbon nanoparticles as a new building block to self-assemble into superlattices.

An easy prepared dual-channel chemosensor for selective and instant detection of fluoride based on double Schiff-base

NASA Astrophysics Data System (ADS)

Leng, Yan-Li; Zhang, Jian-Hui; Li, Qiao; Zhang, You-Ming; Lin, Qi; Yao, Hong; Wei, Tai-Bao

2016-10-01

A colorimetric and fluorescent dual-channel fluoride chemosensor N,N‧-bis (4-diethylaminosalicylidene) hydrazine (sensor S) bearing two imine groups has been designed and synthesized. This structurally simple probe displays rapid response and high selectivity for fluoride over other common anions (Cl-, Br-, I-, AcO-, H2PO4-, HSO4-, ClO4-, CN- and SCN-) in a highly polar aqueous DMSO solution. Mechanism studies suggested that the sensor firstly combined with F- through hydrogen bonds and then experienced the deprotonation process at higher concentrations of F- anion to the two Ar-OH groups. The detection limit was 5.78 × 10- 7 M of F-, which points to the high detection sensitivity. Test strips based on sensor S were fabricated, which could act as a convenient and efficient F- test kit to detect F- for ;in-the-field; measurement.

Development of a colourimetric assay for glycosynthases.

PubMed

Hayes, Marc R; Bochinsky, Kevin A; Seibt, Lisa S; Elling, Lothar; Pietruszka, Jörg

2017-09-10

The synthesis of glycosidic structures by catalysis via glycosynthases has gained much interest due to the potential high product yields and specificity of the enzymes. Nevertheless, the characterisation and implementation of new glycosynthases is greatly hampered by the lack of high-throughput methods for reaction analysis and screening of potential glycosynthase variants. Fluoride detection, via silyl ether chemosensors, has recently shown high potential for the identification of glycosynthase mutants in a high-throughput manner, though limited by the low maximal detection concentration. In the present paper, we describe a new version of a glycosynthase activity assay using a silyl ether of p-nitrophenol, allowing fast reliable detection of fluoride even at concentrations of 4mM and higher. This improvement of detection allows not only screening and identification but also kinetic characterisation of glycosynthases and synthetic reactions in a fast microtiter plate format. The applicability of the assay was successfully demonstrated by the biochemical characterisation of the mesophilic β-glucosynthase of Abg-E358S (Rhizobium radiobacter) and psychrotolerant β-glucosynthase BglU-E377A (Micrococcus antarcticus). The limitation of hyperthermophilic glycosidases as potential glycosynthases, when using glycosyl fluoride donors, was also illustrated by the example of the putative β-galactosidase GalPf from Pyrococcus furiosus. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of different excitation waveforms on detection and characterisation of delamination in PV modules by active infrared thermography

NASA Astrophysics Data System (ADS)

Sinha, Archana; Gupta, Rajesh

2017-10-01

Delamination significantly affects the performance and reliability of photovoltaic (PV) modules. Recently, an active infrared thermography approach using step heating has been exploited for the detection and characterisation of delamination in PV modules. However, step heating takes longer observation time and causes overheating problems. This paper presents the effects of different thermal excitation waveforms namely rectangular, half-sine and short pulse, on the detection and characterisation of delamination in PV module by experiments and simulations. For simulation, a 3-dimensional electro-thermal model of heat conduction, based on resistance-capacitance network approach, has been exploited to study the variation in maximum thermal contrast and peak contrast time with the delamination thickness and heating parameters. Results show that the rectangular waveform provides better detection of delamination due to higher absolute contrast, while the half-sine waveform allows better characterisation of delamination in the PV modules with low-cost and low-power heat source. The high-energy short pulse enabled quick visualisation of delamination, but has limited practical implementation. The advantages and limitations of each waveform have been highlighted to assess the specific requirement for appropriate choice in the non-destructive thermographic inspection of delamination in PV modules at the manufacturing units or outdoor fields.

Real-time PCR assay for the detection and quantification of Legionella pneumophila in environmental water samples: utility for daily practice.

PubMed

Morio, Florent; Corvec, Stéphane; Caroff, Nathalie; Le Gallou, Florence; Drugeon, Henri; Reynaud, Alain

2008-07-01

We developed a quantitative real-time PCR assay targeting the mip gene of Legionella pneumophila for a prospective study from September 2004 to April 2005. It was compared with a standard culture method (French guideline AFNOR T90-431), analysing 120 water samples collected to monitor the risk related to Legionellae at Nantes hospital and to investigate a case of legionellosis acquired from hospital environment. Samples from six distinct water distribution systems were analysed by DNA extraction, amplification and detection with specific primers and FRET probes. The detection limit was 100 genomic units of L. pneumophila per liter (GU/l), the positivity threshold about 600 GU/l and the quantification limit 800 GU/l. PCR results were divided into three groups: negative (n=63), positive but non-quantifiable (n=22) or positive (n=35). PCR showed higher sensitivity than culture, whereas four culture-positive samples appeared negative by PCR (PCR inhibitor detected for two of them). Although no correlation was observed between both methods and real-time PCR cannot substitute for the reference method, it represents an interesting complement. Its sensitivity, reproducibility and rapidity appear particularly interesting in epidemic contexts in order to identify the source of contamination or to evaluate critical points of contamination in water distribution systems.

A Complementary Isothermal Amplification Method to the U.S. EPA Quantitative Polymerase Chain Reaction Approach for the Detection of Enterococci in Environmental Waters

PubMed Central

2017-01-01

We report a novel molecular assay, based on helicase-dependent amplification (HDA), for the detection of enterococci as markers for fecal pollution in water. This isothermal assay targets the same Enterococcus 23S rRNA gene region as the existing quantitative polymerase chain reaction (qPCR) assays of U.S. Environmental Protection Agency Methods 1611 and 1609 but can be entirely performed on a simple heating block. The developed Enterococcus HDA assay successfully discriminated 15 enterococcal from 15 non-enterococcal reference strains and reliably detected 48 environmental isolates of enterococci. The limit of detection was 25 target copies per reaction, only 3 times higher than that of qPCR. The applicability of the assay was tested on 30 environmental water sample DNA extracts, simulating a gradient of fecal pollution. Despite the isothermal nature of the reaction, the HDA results were consistent with those of the qPCR reference. Given this performance, we conclude that the developed Enterococcus HDA assay has great potential as a qualitative molecular screening method for resource-limited settings when combined with compatible up- and downstream processes. This amplification strategy can pave the way for developing a new generation of rapid, low-cost, and field-deployable molecular diagnostic tools for water quality monitoring. PMID:28541661

Automatic detection of confusion in elderly users of a web-based health instruction video.

PubMed

Postma-Nilsenová, Marie; Postma, Eric; Tates, Kiek

2015-06-01

Because of cognitive limitations and lower health literacy, many elderly patients have difficulty understanding verbal medical instructions. Automatic detection of facial movements provides a nonintrusive basis for building technological tools supporting confusion detection in healthcare delivery applications on the Internet. Twenty-four elderly participants (70-90 years old) were recorded while watching Web-based health instruction videos involving easy and complex medical terminology. Relevant fragments of the participants' facial expressions were rated by 40 medical students for perceived level of confusion and analyzed with automatic software for facial movement recognition. A computer classification of the automatically detected facial features performed more accurately and with a higher sensitivity than the human observers (automatic detection and classification, 64% accuracy, 0.64 sensitivity; human observers, 41% accuracy, 0.43 sensitivity). A drill-down analysis of cues to confusion indicated the importance of the eye and eyebrow region. Confusion caused by misunderstanding of medical terminology is signaled by facial cues that can be automatically detected with currently available facial expression detection technology. The findings are relevant for the development of Web-based services for healthcare consumers.

Planck 2015 results: XXVI. The Second Planck Catalogue of Compact Sources

DOE PAGES

Ade, P. A. R.; Aghanim, N.; Argüeso, F.; ...

2016-09-20

The Second Planck Catalogue of Compact Sources is a list of discrete objects detected in single-frequency maps from the full duration of the Planck mission and supersedes previous versions. Also, it consists of compact sources, both Galactic and extragalactic, detected over the entire sky. Compact sources detected in the lower frequency channels are assigned to the PCCS2, while at higher frequencies they are assigned to one of two subcatalogues, the PCCS2 or PCCS2E, depending on their location on the sky. The first of these (PCCS2) covers most of the sky and allows the user to produce subsamples at higher reliabilitiesmore » than the target 80% integral reliability of the catalogue. The second (PCCS2E) contains sources detected in sky regions where the diffuse emission makes it difficult to quantify the reliability of the detections. Both the PCCS2 and PCCS2E include polarization measurements, in the form of polarized flux densities, or upper limits, and orientation angles for all seven polarization-sensitive Planck channels. Finally, the improved data-processing of the full-mission maps and their reduced noise levels allow us to increase the number of objects in the catalogue, improving its completeness for the target 80% reliability as compared with the previous versions, the PCCS and the Early Release Compact Source Catalogue (ERCSC).« less

Planck 2015 results: XXVI. The Second Planck Catalogue of Compact Sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ade, P. A. R.; Aghanim, N.; Argüeso, F.

The Second Planck Catalogue of Compact Sources is a list of discrete objects detected in single-frequency maps from the full duration of the Planck mission and supersedes previous versions. Also, it consists of compact sources, both Galactic and extragalactic, detected over the entire sky. Compact sources detected in the lower frequency channels are assigned to the PCCS2, while at higher frequencies they are assigned to one of two subcatalogues, the PCCS2 or PCCS2E, depending on their location on the sky. The first of these (PCCS2) covers most of the sky and allows the user to produce subsamples at higher reliabilitiesmore » than the target 80% integral reliability of the catalogue. The second (PCCS2E) contains sources detected in sky regions where the diffuse emission makes it difficult to quantify the reliability of the detections. Both the PCCS2 and PCCS2E include polarization measurements, in the form of polarized flux densities, or upper limits, and orientation angles for all seven polarization-sensitive Planck channels. Finally, the improved data-processing of the full-mission maps and their reduced noise levels allow us to increase the number of objects in the catalogue, improving its completeness for the target 80% reliability as compared with the previous versions, the PCCS and the Early Release Compact Source Catalogue (ERCSC).« less

Polyethylenimine carbon nanotube fiber electrodes for enhanced detection of neurotransmitters.

PubMed

Zestos, Alexander G; Jacobs, Christopher B; Trikantzopoulos, Elefterios; Ross, Ashley E; Venton, B Jill

2014-09-02

Carbon nanotube (CNT)-based microelectrodes have been investigated as alternatives to carbon-fiber microelectrodes for the detection of neurotransmitters because they are sensitive, exhibit fast electron transfer kinetics, and are more resistant to surface fouling. Wet spinning CNTs into fibers using a coagulating polymer produces a thin, uniform fiber that can be fabricated into an electrode. CNT fibers formed in poly(vinyl alcohol) (PVA) have been used as microelectrodes to detect dopamine, serotonin, and hydrogen peroxide. In this study, we characterize microelectrodes with CNT fibers made in polyethylenimine (PEI), which have much higher conductivity than PVA-CNT fibers. PEI-CNT fibers have lower overpotentials and higher sensitivities than PVA-CNT fiber microelectrodes, with a limit of detection of 5 nM for dopamine. The currents for dopamine were adsorption controlled at PEI-CNT fiber microelectrodes, independent of scan repetition frequency, and stable for over 10 h. PEI-CNT fiber microelectrodes were resistant to surface fouling by serotonin and the metabolite interferant 5-hydroxyindoleacetic acid (5-HIAA). No change in sensitivity was observed for detection of serotonin after 30 flow injection experiments or after 2 h in 5-HIAA for PEI-CNT electrodes. The antifouling properties were maintained in brain slices when serotonin was exogenously applied multiple times or after bathing the slice in 5-HIAA. Thus, PEI-CNT fiber electrodes could be useful for the in vivo monitoring of neurochemicals.

A New Method for the Fast Analysis of Trihalomethanes in Tap and Recycled Waters Using Headspace Gas Chromatography with Micro-Electron Capture Detection.

PubMed

Alexandrou, Lydon D; Meehan, Barry J; Morrison, Paul D; Jones, Oliver A H

2017-05-15

Chemical disinfection of water supplies brings significant public health benefits by reducing microbial contamination. The process can however, result in the formation of toxic compounds through interactions between disinfectants and organic material in the source water. These new compounds are termed disinfection by-products (DBPs). The most common are the trihalomethanes (THMs) such as trichloromethane (chloroform), dichlorobromomethane, chlorodibromomethane and tribromomethane (bromoform); these are commonly reported as a single value for total trihalomethanes (TTHMs). Analysis of DBPs is commonly performed via time- and solvent-intensive sample preparation techniques such as liquid-liquid and solid phase extraction. In this study, a method using headspace gas chromatography with micro-electron capture detection was developed and applied for the analysis of THMs in drinking and recycled waters from across Melbourne (Victoria, Australia). The method allowed almost complete removal of the sample preparation step whilst maintaining trace level detection limits (>1 ppb). All drinking water samples had TTHM concentrations below the Australian regulatory limit of 250 µg/L but some were above the U.S. EPA limit of 60 µg/L. The highest TTHM concentration was 67.2 µg/L and lowest 22.9 µg/L. For recycled water, samples taken directly from treatment plants held significantly higher concentrations (153.2 µg/L TTHM) compared to samples from final use locations (4.9-9.3 µg/L).

First NuSTAR Limits on Quiet Sun Hard X-Ray Transient Events

NASA Astrophysics Data System (ADS)

Marsh, Andrew J.; Smith, David M.; Glesener, Lindsay; Hannah, Iain G.; Grefenstette, Brian W.; Caspi, Amir; Krucker, Säm; Hudson, Hugh S.; Madsen, Kristin K.; White, Stephen M.; Kuhar, Matej; Wright, Paul J.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Hailey, Charles J.; Harrison, Fiona A.; Stern, Daniel; Zhang, William W.

2017-11-01

We present the first results of a search for transient hard X-ray (HXR) emission in the quiet solar corona with the Nuclear Spectroscopic Telescope Array (NuSTAR) satellite. While NuSTAR was designed as an astrophysics mission, it can observe the Sun above 2 keV with unprecedented sensitivity due to its pioneering use of focusing optics. NuSTAR first observed quiet-Sun regions on 2014 November 1, although out-of-view active regions contributed a notable amount of background in the form of single-bounce (unfocused) X-rays. We conducted a search for quiet-Sun transient brightenings on timescales of 100 s and set upper limits on emission in two energy bands. We set 2.5-4 keV limits on brightenings with timescales of 100 s, expressed as the temperature T and emission measure EM of a thermal plasma. We also set 10-20 keV limits on brightenings with timescales of 30, 60, and 100 s, expressed as model-independent photon fluxes. The limits in both bands are well below previous HXR microflare detections, though not low enough to detect events of equivalent T and EM as quiet-Sun brightenings seen in soft X-ray observations. We expect future observations during solar minimum to increase the NuSTAR sensitivity by over two orders of magnitude due to higher instrument livetime and reduced solar background.

Development of a loop-mediated isothermal amplification assay for detection of Trichomonas vaginalis.

PubMed

Reyes, John Carlo B; Solon, Juan Antonio A; Rivera, Windell L

2014-07-01

A loop-mediated isothermal amplification (LAMP) assay targeting the 2-kbp repeated DNA species-specific sequence was developed for detection of Trichomonas vaginalis, the causative agent of trichomoniasis. The analytical sensitivity and specificity of the LAMP assay were evaluated using pooled genital swab and urine specimens, respectively, spiked with T. vaginalis trophozoites. Genital secretion and urine did not inhibit the detection of the parasite. The sensitivity of the LAMP was 10-1000 times higher than the PCR performed. The detection limit of LAMP was 1 trichomonad for both spiked genital swab and urine specimens. Also, LAMP did not exhibit cross-reactivity with closely-related trichomonads, Trichomonas tenax and Pentatrichomonas hominis, and other enteric and urogenital microorganisms, Entamoeba histolytica, Candida albicans, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. This is the first report of a LAMP assay for the detection of T. vaginalis and has prospective application for rapid diagnosis and control of trichomoniasis. Copyright © 2014 Elsevier Inc. All rights reserved.

DNA-magnetic bead detection using disposable cards and the anisotropic magnetoresistive sensor

NASA Astrophysics Data System (ADS)

Hien, L. T.; Quynh, L. K.; Huyen, V. T.; Tu, B. D.; Hien, N. T.; Phuong, D. M.; Nhung, P. H.; Giang, D. T. H.; Duc, N. H.

2016-12-01

A disposable card incorporating specific DNA probes targeting the 16 S rRNA gene of Streptococcus suis was developed for magnetically labeled target DNA detection. A single-stranded target DNA was hybridized with the DNA probe on the SPA/APTES/PDMS/Si as-prepared card, which was subsequently magnetically labeled with superparamagnetic beads for detection using an anisotropic magnetoresistive (AMR) sensor. An almost linear response between the output signal of the AMR sensor and amount of single-stranded target DNA varied from 4.5 to 18 pmol was identified. From the sensor output signal response towards the mass of magnetic beads which were directly immobilized on the disposable card surface, the limit of detection was estimated about 312 ng ferrites, which corresponds to 3.8 μemu. In comparison with DNA detection by conventional biosensor based on magnetic bead labeling, disposable cards are featured with higher efficiency and performances, ease of use and less running cost with respects to consumables for biosensor in biomedical analysis systems operating with immobilized bioreceptor.

A Novel Isothermal Assay of Borrelia burgdorferi by Recombinase Polymerase Amplification with Lateral Flow Detection.

PubMed

Liu, Wei; Liu, Hui-Xin; Zhang, Lin; Hou, Xue-Xia; Wan, Kang-Lin; Hao, Qin

2016-08-03

A novel isothermal detection for recombinase polymerase amplification with lateral flow (LF-RPA) was established for Borrelia burgdorferi (B. burgdorferi) detection in this study. This assay with high sensitivity and specificity can get a visible result without any additional equipment in 30 min. We designed a pair of primers according to recA gene of B. burgdorferi strains and a methodology evaluation was performed. The results showed that the RPA assay based on the recA gene was successfully applied in B. burgdorferi detection, and its specific amplification was only achieved from the genomic DNA of B. burgdorferi. The detection limit of the new assay was about 25 copies of the B. burgdorferi genomic DNA. Twenty Lyme borreliosis patients' serum samples were detected by LF-RPA assay, real-time qPCR and nested-PCR. Results showed the LF-RPA assay is more effective than nested-PCR for its shorter reaction time and considerably higher detection rate. This method is of great value in clinical rapid detection for Lyme borreliosis. Using the RPA assay might be a megatrend for DNA detection in clinics and endemic regions.

Occurrence of Aflatoxins in Selected Processed Foods from Pakistan

PubMed Central

Mushtaq, Muhammad; Sultana, Bushra; Anwar, Farooq; Khan, Muhammad Zargham; Ashrafuzzaman, Muhammad

2012-01-01

A total of 125 (ready to eat) processed food samples (70 intended for infant and 55 for adult intake) belonging to 20 different food categories were analyzed for aflatoxins contamination using Reverse Phase High Performance Liquid Chromatography (RP-HPLC) with fluorescent detection. A solvent mixture of acetonitrile-water was used for the extraction followed by immunoaffinity clean-up to enhance sensitivity of the method. The limit of detection (LOD) (0.01–0.02 ng·g−1) and limit of quantification (LOQ) (0.02 ng·g−1) was established for aflatoxins based on signal to noise ratio of 3:1 and 10:1, respectively. Of the processed food samples tested, 38% were contaminated with four types of aflatoxins, i.e., AFB1 (0.02–1.24 μg·kg−1), AFB2 (0.02–0.37 μg·kg−1), AFG1 (0.25–2.7 μg·kg−1) and AFG2 (0.21–1.3 μg·kg−1). In addition, the results showed that 21% of the processed foods intended for infants contained AFB1 levels higher than the European Union permissible limits (0.1 μg·kg−1), while all of those intended for adult consumption had aflatoxin contamination levels within the permitted limits. PMID:22942705

Ultra-high dynamic range electro-optic sampling for detecting millimeter and sub-millimeter radiation

PubMed Central

Ibrahim, Akram; Férachou, Denis; Sharma, Gargi; Singh, Kanwarpal; Kirouac-Turmel, Marie; Ozaki, Tsuneyuki

2016-01-01

Time-domain spectroscopy using coherent millimeter and sub-millimeter radiation (also known as terahertz radiation) is rapidly expanding its application, owing greatly to the remarkable advances in generating and detecting such radiation. However, many current techniques for coherent terahertz detection have limited dynamic range, thus making it difficult to perform some basic experiments that need to directly compare strong and weak terahertz signals. Here, we propose and demonstrate a novel technique based on cross-polarized spectral-domain interferometry to achieve ultra-high dynamic range electro-optic sampling measurement of coherent millimeter and sub-millimeter radiation. In our scheme, we exploit the birefringence in a single-mode polarization maintaining fiber in order to measure the phase change induced by the electric field of terahertz radiation in the detection crystal. With our new technique, we have achieved a dynamic range of 7 × 106, which is 4 orders of magnitude higher than conventional electro-optic sampling techniques, while maintaining comparable signal-to-noise ratio. The present technique is foreseen to have great impact on experiments such as linear terahertz spectroscopy of optically thick materials (such as aqueous samples) and nonlinear terahertz spectroscopy, where the higher dynamic range is crucial for proper interpretation of experimentally obtained results. PMID:26976363

Coordination ability determined transition metal ions substitution of Tb in Tb-Asp fluorescent nanocrystals and a facile ions-detection approach.

PubMed

Duan, Jiazhi; Ma, Baojin; Liu, Feng; Zhang, Shan; Wang, Shicai; Kong, Ying; Du, Min; Han, Lin; Wang, Jianjun; Sang, Yuanhua; Liu, Hong

2018-04-26

Although the synthesis and fluorescent properties of lanthanide-amino acid complex nanostructures have been investigated extensively, limited studies have been reported on metal ions' substitution ability for the lanthanide ions in the complex and their effect on the fluorescent property. In this study, taking biocompatible Tb-aspartic acid (Tb-Asp) complex nanocrystals as a model, the substitution mechanism of metal ions, particularly transition metals, for Tb ions in Tb-Asp nanocrystals and the change in the fluorescent property of the Tb-Asp nanocrystals after substitution were systematically investigated. The experimental results illustrated that metal ions with higher electronegativity, higher valence, and smaller radius possess stronger ability for Tb ions' substitution in Tb-Asp nanocrystals. Based on the effect of substituting ions' concentration on the fluorescent property of Tb-Asp, a facile method for copper ions detection with high sensitivity was proposed by measuring the fluorescent intensity of Tb-Asp nanocrystals' suspensions containing different concentrations of copper ions. The good biocompatibility, great convenience of synthesis and sensitive detection ability make Tb-Asp nanocrystals a very low cost and effective material for metal ions detection, which also opens a new door for practical applications of metal-Asp coordinated nanocrystals.

Construction of a combinatorial pipeline using two somatic variant  calling  methods  for whole exome sequence data of gastric cancer.

PubMed

Kohmoto, Tomohiro; Masuda, Kiyoshi; Naruto, Takuya; Tange, Shoichiro; Shoda, Katsutoshi; Hamada, Junichi; Saito, Masako; Ichikawa, Daisuke; Tajima, Atsushi; Otsuji, Eigo; Imoto, Issei

2017-01-01

High-throughput next-generation sequencing is a powerful tool to identify the genotypic landscapes of somatic variants and therapeutic targets in various cancers including gastric cancer, forming the basis for personalized medicine in the clinical setting. Although the advent of many computational algorithms leads to higher accuracy in somatic variant calling, no standard method exists due to the limitations of each method. Here, we constructed a new pipeline. We combined two different somatic variant callers with different algorithms, Strelka and VarScan 2, and evaluated performance using whole exome sequencing data obtained from 19 Japanese cases with gastric cancer (GC); then, we characterized these tumors based on identified driver molecular alterations. More single nucleotide variants (SNVs) and small insertions/deletions were detected by Strelka and VarScan 2, respectively. SNVs detected by both tools showed higher accuracy for estimating somatic variants compared with those detected by only one of the two tools and accurately showed the mutation signature and mutations of driver genes reported for GC. Our combinatorial pipeline may have an advantage in detection of somatic mutations in GC and may be useful for further genomic characterization of Japanese patients with GC to improve the efficacy of GC treatments. J. Med. Invest. 64: 233-240, August, 2017.

Ultra-high dynamic range electro-optic sampling for detecting millimeter and sub-millimeter radiation.

PubMed

Ibrahim, Akram; Férachou, Denis; Sharma, Gargi; Singh, Kanwarpal; Kirouac-Turmel, Marie; Ozaki, Tsuneyuki

2016-03-15

Time-domain spectroscopy using coherent millimeter and sub-millimeter radiation (also known as terahertz radiation) is rapidly expanding its application, owing greatly to the remarkable advances in generating and detecting such radiation. However, many current techniques for coherent terahertz detection have limited dynamic range, thus making it difficult to perform some basic experiments that need to directly compare strong and weak terahertz signals. Here, we propose and demonstrate a novel technique based on cross-polarized spectral-domain interferometry to achieve ultra-high dynamic range electro-optic sampling measurement of coherent millimeter and sub-millimeter radiation. In our scheme, we exploit the birefringence in a single-mode polarization maintaining fiber in order to measure the phase change induced by the electric field of terahertz radiation in the detection crystal. With our new technique, we have achieved a dynamic range of 7 × 10(6), which is 4 orders of magnitude higher than conventional electro-optic sampling techniques, while maintaining comparable signal-to-noise ratio. The present technique is foreseen to have great impact on experiments such as linear terahertz spectroscopy of optically thick materials (such as aqueous samples) and nonlinear terahertz spectroscopy, where the higher dynamic range is crucial for proper interpretation of experimentally obtained results.

Novel Junction-specific and Quantifiable In Situ Detection of AR-V7 and its Clinical Correlates in Metastatic Castration-resistant Prostate Cancer.

PubMed

Zhu, Yezi; Sharp, Adam; Anderson, Courtney M; Silberstein, John L; Taylor, Maritza; Lu, Changxue; Zhao, Pei; De Marzo, Angelo M; Antonarakis, Emmanuel S; Wang, Mindy; Wu, Xingyong; Luo, Yuling; Su, Nan; Nava Rodrigues, Daniel; Figueiredo, Ines; Welti, Jonathan; Park, Emily; Ma, Xiao-Jun; Coleman, Ilsa; Morrissey, Colm; Plymate, Stephen R; Nelson, Peter S; de Bono, Johann S; Luo, Jun

2018-05-01

Androgen receptor splice variant 7 (AR-V7) has been implicated in resistance to abiraterone and enzalutamide treatment in men with metastatic castration-resistant prostate cancer (mCRPC). Tissue- or cell-based in situ detection of AR-V7, however, has been limited by lack of specificity. To address current limitations in precision measurement of AR-V7 by developing a novel junction-specific AR-V7 RNA in situ hybridization (RISH) assay compatible with automated quantification. We designed a RISH method to visualize single splice junctions in cells and tissue. Using the validated assay for junction-specific detection of the full-length AR (AR-FL) and AR-V7, we generated quantitative data, blinded to clinical data, for 63 prostate tumor biopsies. We evaluated clinical correlates of AR-FL/AR-V7 measurements, including association with prostate-specific antigen progression-free survival (PSA-PFS) and clinical and radiographic progression-free survival (PFS), in a subset of patients starting treatment with abiraterone or enzalutamide following biopsy. Quantitative AR-FL/AR-V7 data were generated from 56 of the 63 (88.9%) biopsy specimens examined, of which 44 were mCRPC biopsies. Positive AR-V7 signals were detected in 34.1% (15/44) mCRPC specimens, all of which also co-expressed AR-FL. The median AR-V7/AR-FL ratio was 11.9% (range 2.7-30.3%). Positive detection of AR-V7 was correlated with indicators of high disease burden at baseline. Among the 25 CRPC biopsies collected before treatment with abiraterone or enzalutamide, positive AR-V7 detection, but not higher AR-FL, was significantly associated with shorter PSA-PFS (hazard ratio 2.789, 95% confidence interval 1.12-6.95; p=0.0081). We report for the first time a RISH method for highly specific and quantifiable detection of splice junctions, allowing further characterization of AR-V7 and its clinical significance. Higher AR-V7 levels detected and quantified using a novel method were associated with poorer response to abiraterone or enzalutamide in prostate cancer. Copyright © 2017 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Investigation of the limitations of the highly pixilated CdZnTe detector for PET applications

PubMed Central

Komarov, Sergey; Yin, Yongzhi; Wu, Heyu; Wen, Jie; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2016-01-01

We are investigating the feasibility of a high resolution positron emission tomography (PET) insert device based on the CdZnTe detector with 350 μm anode pixel pitch to be integrated into a conventional animal PET scanner to improve its image resolution. In this paper, we have used a simplified version of the multi pixel CdZnTe planar detector, 5 mm thick with 9 anode pixels only. This simplified 9 anode pixel structure makes it possible to carry out experiments without a complete application-specific integrated circuits readout system that is still under development. Special attention was paid to the double pixel (or charge sharing) detections. The following characteristics were obtained in experiment: energy resolution full-width-at-half-maximum (FWHM) is 7% for single pixel and 9% for double pixel photoelectric detections of 511 keV gammas; timing resolution (FWHM) from the anode signals is 30 ns for single pixel and 35 ns for double pixel detections (for photoelectric interactions only the corresponding values are 20 and 25 ns); position resolution is 350 μm in x,y-plane and ~0.4 mm in depth-of-interaction. The experimental measurements were accompanied by Monte Carlo (MC) simulations to find a limitation imposed by spatial charge distribution. Results from MC simulations suggest the limitation of the intrinsic spatial resolution of the CdZnTe detector for 511 keV photoelectric interactions is 170 μm. The interpixel interpolation cannot recover the resolution beyond the limit mentioned above for photoelectric interactions. However, it is possible to achieve higher spatial resolution using interpolation for Compton scattered events. Energy and timing resolution of the proposed 350 μm anode pixel pitch detector is no better than 0.6% FWHM at 511 keV, and 2 ns FWHM, respectively. These MC results should be used as a guide to understand the performance limits of the pixelated CdZnTe detector due to the underlying detection processes, with the understanding of the inherent limitations of MC methods. PMID:23079763

Investigation of the limitations of the highly pixilated CdZnTe detector for PET applications.

PubMed

Komarov, Sergey; Yin, Yongzhi; Wu, Heyu; Wen, Jie; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2012-11-21

We are investigating the feasibility of a high resolution positron emission tomography (PET) insert device based on the CdZnTe detector with 350 µm anode pixel pitch to be integrated into a conventional animal PET scanner to improve its image resolution. In this paper, we have used a simplified version of the multi pixel CdZnTe planar detector, 5 mm thick with 9 anode pixels only. This simplified 9 anode pixel structure makes it possible to carry out experiments without a complete application-specific integrated circuits readout system that is still under development. Special attention was paid to the double pixel (or charge sharing) detections. The following characteristics were obtained in experiment: energy resolution full-width-at-half-maximum (FWHM) is 7% for single pixel and 9% for double pixel photoelectric detections of 511 keV gammas; timing resolution (FWHM) from the anode signals is 30 ns for single pixel and 35 ns for double pixel detections (for photoelectric interactions only the corresponding values are 20 and 25 ns); position resolution is 350 µm in x,y-plane and ∼0.4 mm in depth-of-interaction. The experimental measurements were accompanied by Monte Carlo (MC) simulations to find a limitation imposed by spatial charge distribution. Results from MC simulations suggest the limitation of the intrinsic spatial resolution of the CdZnTe detector for 511 keV photoelectric interactions is 170 µm. The interpixel interpolation cannot recover the resolution beyond the limit mentioned above for photoelectric interactions. However, it is possible to achieve higher spatial resolution using interpolation for Compton scattered events. Energy and timing resolution of the proposed 350 µm anode pixel pitch detector is no better than 0.6% FWHM at 511 keV, and 2 ns FWHM, respectively. These MC results should be used as a guide to understand the performance limits of the pixelated CdZnTe detector due to the underlying detection processes, with the understanding of the inherent limitations of MC methods.

Suitability of pharmaceuticals and personal care products (PPCPs) and artificial sweeteners (ASs) as wastewater indicators in the Pearl River Delta, South China.

PubMed

Yang, Yuan-Yuan; Liu, Wang-Rong; Liu, You-Sheng; Zhao, Jian-Liang; Zhang, Qian-Qian; Zhang, Min; Zhang, Jin-Na; Jiang, Yu-Xia; Zhang, Li-Juan; Ying, Guang-Guo

2017-07-15

Wastewater indicator is a useful tool for evaluating the wastewater impact on natural water, but there is little information about the suitability of wastewater indicators for different regions. This study aimed to select suitable wastewater indicators in the Pearl River Delta region, south China by screening a range of wastewater related organic compounds. The screening campaign was carried out by investigating the occurrence and removal efficiencies of 93 pharmaceuticals and personal care products (PPCPs) and 5 artificial sweeteners (ASs) in nine wastewater treatment plants (WWTPs) located in the region, and the occurrence of these target compounds in the contaminated and clean surface water of the Pearl River. An ideal wastewater indicator should be hydrophilic, source-specific for domestic wastewater, ubiquitous in contaminated surface water with detection frequency (DF) >80% and absent in background water samples. For liable indicators, high removal rates (>90%) should be observed in WWTPs and they should be detected in all the influent samples at concentrations fifty times higher than their limits of quantification. For conservative indicators, low removal rates (<50%) should be observed in WWTPs and they should be detected in all the effluent samples at concentrations fifty times higher than their limits of quantification. Based on the above criteria, sucralose and fluconazole were selected as conservative indicators in the region, while cyclamate, saccharin, methyl paraben, ethyl paraben, propyl paraben, paracetamol, salicylic acid and caffeine were selected as liable indicators. Copyright © 2017 Elsevier B.V. All rights reserved.

The HOSTS Survey—Exozodiacal Dust Measurements for 30 Stars

NASA Astrophysics Data System (ADS)

Ertel, S.; Defrère, D.; Hinz, P.; Mennesson, B.; Kennedy, G. M.; Danchi, W. C.; Gelino, C.; Hill, J. M.; Hoffmann, W. F.; Rieke, G.; Shannon, A.; Spalding, E.; Stone, J. M.; Vaz, A.; Weinberger, A. J.; Willems, P.; Absil, O.; Arbo, P.; Bailey, V. P.; Beichman, C.; Bryden, G.; Downey, E. C.; Durney, O.; Esposito, S.; Gaspar, A.; Grenz, P.; Haniff, C. A.; Leisenring, J. M.; Marion, L.; McMahon, T. J.; Millan-Gabet, R.; Montoya, M.; Morzinski, K. M.; Pinna, E.; Power, J.; Puglisi, A.; Roberge, A.; Serabyn, E.; Skemer, A. J.; Stapelfeldt, K.; Su, K. Y. L.; Vaitheeswaran, V.; Wyatt, M. C.

2018-05-01

The Hunt for Observable Signatures of Terrestrial Systems survey searches for dust near the habitable zones (HZs) around nearby, bright main-sequence stars. We use nulling interferometry in the N band to suppress the bright stellar light and to probe for low levels of HZ dust around the 30 stars observed so far. Our overall detection rate is 18%, including four new detections, among which are the first three around Sun-like stars and the first two around stars without any previously known circumstellar dust. The inferred occurrence rates are comparable for early-type and Sun-like stars, but decrease from {60}-21+16% for stars with previously detected cold dust to {8}-3+10% for stars without such excess, confirming earlier results at higher sensitivity. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal excess luminosity function, we put upper limits on the median HZ dust level of 13 zodis (95% confidence) for a sample of stars without cold dust and of 26 zodis when focusing on Sun-like stars without cold dust. However, our data suggest that a more complex luminosity function may be more appropriate. For stars without detectable Large Binocular Telescope Interferometer (LBTI) excess, our upper limits are almost reduced by a factor of two, demonstrating the strength of LBTI target vetting for future exo-Earth imaging missions. Our statistics are limited so far, and extending the survey is critical to informing the design of future exo-Earth imaging surveys.

Secondary electrospray ionization-ion mobility spectrometry for explosive vapor detection.

PubMed

Tam, Maggie; Hill, Herbert H

2004-05-15

The unique capability of secondary electrospray ionization (SESI) as a nonradioactive ionization source to detect analytes in both liquid and gaseous samples was evaluated using aqueous solutions of three common military explosives: cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX), nitroglycerin (NG) and pentaerythritol tetranitrate (PETN). The adducts formed between the compounds and their respective dissociation product, RDX.NO(2)(-), NG.NO(3)(-), and PETN.NO(3)(-), gave the most intense signal for the individual compound but were more sensitive to temperature than other species. These autoadducts were identified as RDX.NO(2)(-), NG.NO(3)(-), and PETN.NO(3)(-) and had maximum signal intensity at 137, 100, and 125 degrees C, respectively. The reduced mobility values of the three compounds were constant over the temperature range from 75 to 225 degrees C. The signal-to-noise ratios for RDX, NG, and PETN at 50 mg L(-1) in methanol-water were 340, 270, and 170, respectively, with a nominal noise of 8 +/- 2 pA. In addition to the investigation of autoadduct formation, the concept of doping the ionization source with nonvolatile adduct-forming agents was investigated and described for the first time. The SESI-IMS detection limit for RDX was 116 microg L(-1) in the presence of a traditional volatile chloride dopant and 5.30 microg L(-1) in the presence of a nonvolatile nitrate dopant. In addition to a lower detection limit, the nitrate dopant also produced a greater response sensitivity and a higher limit of linearity than did the traditional volatile chloride dopant.

Fast determination of octinoxate and oxybenzone uv filters in swimming pool waters by gas chromatography/mass spectrometry after solid-phase microextraction.

PubMed

Yılmazcan, Ö; Kanakaki, C; Izgi, B; Rosenberg, E

2015-07-01

A fast gas chromatography/mass spectrometry method was developed and validated for the analysis of the potential endocrine disrupters octinoxate and oxybenzone in swimming pool water samples based on the solvent-free solid-phase microextraction technique. The low-pressure gas chromatography/mass spectrometry method used for the fast identification of UV filter substances was compared to a conventional method in terms of sensitivity and speed. The fast method proposed resulted in 2 min runs, leading to an eightfold decrease in the total analysis time and a sevenfold improvement in detection limits. The main parameters affecting the solid-phase microextraction process were also studied in detail and the optimized conditions were as follows: fiber coating, polyacrylate; extraction mode, direct immersion; extraction temperature, 25°C; sample volume, 5 mL; extraction time 45 min; pH 6.5. Under the optimized conditions, a linear response was obtained in the concentration range of 0.5-25 μg/L with correlation coefficients in the range 0.990-0.999. The limits of detection were 0.17-0.29 μg/L, and the recoveries were 80-83%. Combined method uncertainty was assessed and found to be less than 7% for both analytes for concentrations equal to or higher than 5 μg/L. Pool water samples were analyzed to demonstrate the applicability of the proposed method. Neither octinoxate nor oxybenzone were detected in the swimming pool water samples at concentrations above the respective limits of detection. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Compliant finger sensor for sensorimotor studies in MEG and MR environment

NASA Astrophysics Data System (ADS)

Li, Y.; Yong, X.; Cheung, T. P. L.; Menon, C.

2016-07-01

Magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) are widely used for functional brain imaging. The correlations between the sensorimotor functions of the hand and brain activities have been investigated in MEG/fMRI studies. Currently, limited information can be drawn from these studies due to the limitations of existing motion sensors that are used to detect hand movements. One major challenge in designing these motion sensors is to limit the signal interference between the motion sensors and the MEG/fMRI. In this work, a novel finger motion sensor, which contains low-ferromagnetic and non-conductive materials, is introduced. The finger sensor consists of four air-filled chambers. When compressed by finger(s), the pressure change in the chambers can be detected by the electronics of the finger sensor. Our study has validated that the interference between the finger sensor and an MEG is negligible. Also, by applying a support vector machine algorithm to the data obtained from the finger sensor, at least 11 finger patterns can be discriminated. Comparing to the use of traditional electromyography (EMG) in detecting finger motion, our proposed finger motion sensor is not only MEG/fMRI compatible, it is also easy to use. As the signals acquired from the sensor have a higher SNR than that of the EMG, no complex algorithms are required to detect different finger movement patterns. Future studies can utilize this motion sensor to investigate brain activations during different finger motions and correlate the activations with the sensory and motor functions respectively.

Presence of noroviruses and other enteric viruses in sewage and surface waters in The Netherlands.

PubMed

Lodder, W J; de Roda Husman, A M

2005-03-01

Since virus concentrations in drinking waters are generally below the detection limit, the infectious risk from drinking water consumption requires assessment from the virus concentrations in source waters and removal efficiency of treatment processes. In this study, we estimated from reverse transcription-PCR on 10-fold serially diluted RNA that noroviruses, the most prevalent waterborne gastroenteritis agents, were present at 4 (0.2 to 38) to 4,900 (303 to 4.6 x 10(4)) PCR-detectable units (PDU) per liter of river water (ranges are given in parentheses). These virus concentrations are still high compared with 896 to 7,499 PDU/liter of treated sewage and 5,111 to 850,000 PDU/liter in raw sewage. Sequencing analyses designated human norovirus GGII.4 Lordsdale as the most prevalent strain in the sampling period 1998 to 1999 in both sewage and surface waters. Other GGII strains were also very abundant, indicating that the majority of the virus contamination was derived from urban sewage, although very divergent strains and one animal strain were also detected in the surface and sewage waters. Rotaviruses were also detected in two large rivers (the Maas and the Waal) at 57 to 5,386 PDU/liter. The high virus concentrations determined by PCR may in part be explained by the detection of virus RNA instead of infectious particles. Indeed, reoviruses and enteroviruses that can be cultured were present at much lower levels, of 0.3 to 1 and 2 to 10 PFU/liter, respectively. Assuming 1% of the noroviruses and rotaviruses to be infectious, a much higher disease burden than for other viruses can be expected, not only because of the higher levels but also because of these viruses' higher infectivity and attack rates.

Presence of Noroviruses and Other Enteric Viruses in Sewage and Surface Waters in The Netherlands

PubMed Central

Lodder, W. J.; de Roda Husman, A. M.

2005-01-01

Since virus concentrations in drinking waters are generally below the detection limit, the infectious risk from drinking water consumption requires assessment from the virus concentrations in source waters and removal efficiency of treatment processes. In this study, we estimated from reverse transcription-PCR on 10-fold serially diluted RNA that noroviruses, the most prevalent waterborne gastroenteritis agents, were present at 4 (0.2 to 38) to 4,900 (303 to 4.6 × 104) PCR-detectable units (PDU) per liter of river water (ranges are given in parentheses). These virus concentrations are still high compared with 896 to 7,499 PDU/liter of treated sewage and 5,111 to 850,000 PDU/liter in raw sewage. Sequencing analyses designated human norovirus GGII.4 Lordsdale as the most prevalent strain in the sampling period 1998 to 1999 in both sewage and surface waters. Other GGII strains were also very abundant, indicating that the majority of the virus contamination was derived from urban sewage, although very divergent strains and one animal strain were also detected in the surface and sewage waters. Rotaviruses were also detected in two large rivers (the Maas and the Waal) at 57 to 5,386 PDU/liter. The high virus concentrations determined by PCR may in part be explained by the detection of virus RNA instead of infectious particles. Indeed, reoviruses and enteroviruses that can be cultured were present at much lower levels, of 0.3 to 1 and 2 to 10 PFU/liter, respectively. Assuming 1% of the noroviruses and rotaviruses to be infectious, a much higher disease burden than for other viruses can be expected, not only because of the higher levels but also because of these viruses' higher infectivity and attack rates. PMID:15746348

VIRAL LOAD AND SHORT-TERM NATURAL HISTORY OF TYPE-SPECIFIC ONCOGENIC HUMAN PAPILLOMAVIRUS INFECTIONS IN A HIGH-RISK COHORT OF MID-ADULT WOMEN

PubMed Central

Winer, Rachel L.; Xi, Long Fu; Shen, Zhenping; Stern, Joshua E.; Newman, Laura; Feng, Qinghua; Hughes, James P.; Koutsky, Laura A.

2013-01-01

Oncogenic human papillomavirus (HPV) viral load may inform the origin of newly detected infections and characterize oncogenic HPV natural history in mid-adult women. From 2007–2011, we enrolled 521 25–65 year old female online daters and followed them triannually with mailed health and sexual behavior questionnaires and kits for self-sampling for PCR-based HPV DNA testing. Samples from oncogenic HPV positive women were selected for type-specific DNA load testing by real-time PCR with adjustment for cellularity. Linear or logistic regression models were used to evaluate relationships between viral levels, health and sexual behavior, and longitudinal oncogenic HPV detection. Type-specific viral levels were borderline significantly higher in oncogenic HPV infections that were prevalent versus newly detected (p=0.092), but levels in newly detected infections were higher than in infections re-detected after intercurrent negativity (p<.001). Recent sex partners were not significantly associated with viral levels. Compared to prevalent infections detected intermittently, the likelihood of persistent (OR=4.31,95%CI:2.20–8.45) or single-time (OR=1.32,95%CI:1.03–1.71) detection increased per 1-unit increase in baseline log10 viral load. Viral load differences between re-detected and newly detected infections suggest a portion of new detections were due to new acquisition, although report of recent new sex partners (a potential marker of new infection) was not predictive of viral load; oncogenic HPV infections in mid-adult women with new partners likely represent a mix of new acquisition and reactivation or intermittent detection of previous infection. Intermittent detection was characterized by low viral levels, suggesting that intermittent detection of persisting oncogenic HPV infection may be of limited clinical significance PMID:24136492

Is Endotoxemia in Stable Hemodialysis Patients an Artefact? Limitations of the Limulus Amebocyte Lysate Assay and Role of (1→3)-β-D Glucan

PubMed Central

Zhang, Yonglong; Patidar, Ashish; Vilar, Enric; Finkelman, Malcolm; Farrington, Ken

2016-01-01

Background Elevated blood endotoxin levels are frequently reported in the dialysis population and are strongly linked with inflammation, a major predictor of mortality. Virtually all studies have employed the Limulus Amoebocyte Lysate (LAL) assay to detect endotoxin. However this assay is not endotoxin-specific and can be activated by (1→3)-β-glucan (BG), a component of fungal cell walls leading to false positive signals. Very few studies have taken account of this. We examined the influence of BG-based activation of the LAL assay on the detection of endotoxemia in this setting. Method We measured plasma endotoxin levels in 50 hemodialysis patients with and without the use of BG-blocking buffers. These buffers inhibit BG activation of the LAL assay to ensure that any signal detected is endotoxin-specific. Blood samples were measured for BG, interleukin-6 (IL-6), tumor necrosis factor-alfa (TNF-α) to examine the association between endotoxin signals, BG and inflammation. Results Endotoxin signals were detected in 50% of patients. On repeat measurement with a BG-blocking buffer, all detected endotoxin signals were extinguished. No patient had detectable endotoxemia. Plasma BG levels were significantly elevated in 58% of patients and were higher in those with detectable endotoxin signals using the LAL assay without BG-blocking buffers (78vs.54pg/mL;p<0.001). Endotoxin signal and BG levels did not correlate with levels of TNF-α or IL-6. Conclusion Use of the LAL assay for blood endotoxin detection in dialysis patients has its limitations due to high blood BG. Endotoxemia frequently reported in non-infected hemodialysis patients may be artefactual due to BG interference. PMID:27764208

Environmental analysis of higher brominated diphenyl ethers and decabromodiphenyl ethane.

PubMed

Kierkegaard, Amelie; Sellström, Ulla; McLachlan, Michael S

2009-01-16

Methods for environmental analysis of higher brominated diphenyl ethers (PBDEs), in particular decabromodiphenyl ether (BDE209), and the recently discovered environmental contaminant decabromodiphenyl ethane (deBDethane) are reviewed. The extensive literature on analysis of BDE209 has identified several critical issues, including contamination of the sample, degradation of the analyte during sample preparation and GC analysis, and the selection of appropriate detection methods and surrogate standards. The limited experience with the analysis of deBDethane suggests that there are many commonalities with BDE209. The experience garnered from the analysis of BDE209 over the last 15 years will greatly facilitate progress in the analysis of deBDethane.

Signatures of particle acceleration at SN 1987A

NASA Technical Reports Server (NTRS)

Gaisser, T. K.; Stanev, Todor; Harding, Alice K.

1989-01-01

At least eight experiments are currently monitoring SN 1987A for photons or neutrinos with energies in the TeV range or higher. Observation of such signals would indicate that the supernova is the site of acceleration of charged particles to even higher energies. The way that the acceleration might occur is discussed, and the prospects for detection of such signals in light of current limits on power in the supernova from sources other than the nickel-cobalt-iron decay chain are evaluated. It is pointed out that signals of particle acceleration may show up in continuum MeV gamma rays as well as in the 100 MeV range.

Distribution and environmental limitations of an amphibian pathogen in the Rocky Mountains, USA

USGS Publications Warehouse

Muths, E.; Pilliod, D.S.; Livo, L.J.

2008-01-01

Amphibian populations continue to be imperiled by the chytrid fungus (Batrachochytrium dendrobatidis). Understanding where B. dendrobatidis (Bd) occurs and how it may be limited by environmental factors is critical to our ability to effectively conserve the amphibians affected by Bd. We sampled 1247 amphibians (boreal toads and surrogates) at 261 boreal toad (Bufo boreas) breeding sites (97 clusters) along an 11?? latitudinal gradient in the Rocky Mountains to determine the distribution of B. dendrobatidis and examine environmental factors, such as temperature and elevation, that might affect its distribution. The fungus was detected at 64% of all clusters and occurred across a range of elevations (1030-3550 m) and latitudes (37.6-48.6??) but we detected it in only 42% of clusters in the south (site elevations higher), compared to 84% of clusters in the north (site elevations lower). Maximum ambient temperature (daily high) explained much of the variation in Bd occurrence in boreal toad populations and thus perhaps limits the occurrence of the pathogen in the Rocky Mountains to areas where climatic conditions facilitate optimal growth of the fungus. This information has implications in global climate change scenarios where warming temperatures may facilitate the spread of disease into previously un- or little-affected areas (i.e., higher elevations). This study provides the first regional-level, field-based effort to examine the relationship of environmental and geographic factors to the distribution of B. dendrobatidis in North America and will assist managers to focus on at-risk populations as determined by the local temperature regimes, latitude and elevation.

VaDiR: an integrated approach to Variant Detection in RNA.

PubMed

Neums, Lisa; Suenaga, Seiji; Beyerlein, Peter; Anders, Sara; Koestler, Devin; Mariani, Andrea; Chien, Jeremy

2018-02-01

Advances in next-generation DNA sequencing technologies are now enabling detailed characterization of sequence variations in cancer genomes. With whole-genome sequencing, variations in coding and non-coding sequences can be discovered. But the cost associated with it is currently limiting its general use in research. Whole-exome sequencing is used to characterize sequence variations in coding regions, but the cost associated with capture reagents and biases in capture rate limit its full use in research. Additional limitations include uncertainty in assigning the functional significance of the mutations when these mutations are observed in the non-coding region or in genes that are not expressed in cancer tissue. We investigated the feasibility of uncovering mutations from expressed genes using RNA sequencing datasets with a method called Variant Detection in RNA(VaDiR) that integrates 3 variant callers, namely: SNPiR, RVBoost, and MuTect2. The combination of all 3 methods, which we called Tier 1 variants, produced the highest precision with true positive mutations from RNA-seq that could be validated at the DNA level. We also found that the integration of Tier 1 variants with those called by MuTect2 and SNPiR produced the highest recall with acceptable precision. Finally, we observed a higher rate of mutation discovery in genes that are expressed at higher levels. Our method, VaDiR, provides a possibility of uncovering mutations from RNA sequencing datasets that could be useful in further functional analysis. In addition, our approach allows orthogonal validation of DNA-based mutation discovery by providing complementary sequence variation analysis from paired RNA/DNA sequencing datasets.

Effectiveness of medicines authentication technology to detect counterfeit, recalled and expired medicines: a two-stage quantitative secondary care study.

PubMed

Naughton, Bernard; Roberts, Lindsey; Dopson, Sue; Chapman, Stephen; Brindley, David

2016-12-09

To identify the authentication and detection rate of serialised medicines using medicines authentication technology. 4192 serialised medicines were entered into a hospital dispensary over two separate 8-week stages in 2015. Medicines were authenticated using secure external database cross-checking, triggered by the scanning of a two-dimensional data matrix with a unit specific 12-digit serial code. 4% of medicines included were preprogrammed with a message to identify the product as either expired, pack recalled, product recalled or counterfeit. A site within a large UK National Health Service teaching hospital trust. Accredited checking staff, pharmacists and dispensers in a pharmacy department. Authentication and detection rate of counterfeit expired and recalled medicines. The operational detection rate of counterfeit, recalled and expired medicines scanned as a combined group was 81.4% (stage 1 (S1)) and 87% (stage 2 (S2)). The technology's technical detection rate (TDR) was 100%; however, not all medicines were scanned and of those that were scanned not all that generated a warning message were quarantined. Owing to an operational authentication rate (OAR) of 66.3% (over both stages), only 31.8% of counterfeit medicines, 58% of recalled drugs and 64% of expired medicines were detected as a proportion of those entered into the study. Response times (RTs) of 152 ms (S1) and 165 ms (S2) were recorded, meeting the falsified medicines directive-mandated 300 ms limit. TDRs and RTs were not a limiting factor in this study. The suboptimal OAR poses significant quality and safety issues with this detection approach. Authentication at the checking stage, however, demonstrated higher OARs. There is a need for further qualitative research to establish the reasons for less than absolute authentication and detection rates in the hospital environment to improve this technology in preparation for the incumbent European Union regulative deadline. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Analytical method development for the determination of emerging contaminants in water using supercritical-fluid chromatography coupled with diode-array detection.

PubMed

Del Carmen Salvatierra-Stamp, Vilma; Ceballos-Magaña, Silvia G; Gonzalez, Jorge; Ibarra-Galván, Valentin; Muñiz-Valencia, Roberto

2015-05-01

An analytical method using supercritical-fluid chromatography coupled with diode-array detection for the determination of seven emerging contaminants-two pharmaceuticals (carbamazepine and glyburide), three endocrine disruptors (17α-ethinyl estradiol, bisphenol A, and 17β-estradiol), one bactericide (triclosan), and one pesticide (diuron)-was developed and validated. These contaminants were chosen because of their frequency of use and their toxic effects on both humans and the environment. The optimized chromatographic separation on a Viridis BEH 2-EP column achieved baseline resolution for all compounds in less than 10 min. This separation was applied to environmental water samples after sample preparation. The optimized sample treatment involved a preconcentration step by means of solid-phase extraction using C18-OH cartridges. The proposed method was validated, finding recoveries higher than 94 % and limits of detection and limits of quantification in the range of 0.10-1.59 μg L(-1) and 0.31-4.83 μg L(-1), respectively. Method validation established the proposed method to be selective, linear, accurate, and precise. Finally, the method was successfully applied to environmental water samples.

Sensitive detection of chemical agents and toxic industrial chemicals using active open-path FTIRs

NASA Astrophysics Data System (ADS)

Walter, William T.

2004-03-01

Active open-path FTIR sensors provide more sensitive detection of chemical agents than passive FTIRs, such as the M21 RSCAAL and JSLSCAD, and at the same time identify and quantify toxic industrial chemicals (TIC). Passive FTIRs are bistatic sensors relying on infrared sources of opportunity. Utilization of earth-based sources of opportunity limits the source temperatures available for passive chemical-agent FTIR sensors to 300° K. Active FTIR chemical-agent sensors utilize silicon carbide sources, which can be operated at 1500° K. The higher source temperature provides more than an 80-times increase in the infrared radiant flux emitted per unit area in the 7 to 14 micron spectral fingerprint region. Minimum detection limits are better than 5 μgm/m3 for GA, GB, GD, GF and VX. Active FTIR sensors can (1) assist first responders and emergency response teams in their assessment of and reaction to a terrorist threat, (2) provide information on the identification of the TIC present and their concentrations and (3) contribute to the understanding and prevention of debilitating disorders analogous to the Gulf War Syndrome for military and civilian personnel.

Wideband optical sensing using pulse interferometry.

PubMed

Rosenthal, Amir; Razansky, Daniel; Ntziachristos, Vasilis

2012-08-13

Advances in fabrication of high-finesse optical resonators hold promise for the development of miniaturized, ultra-sensitive, wide-band optical sensors, based on resonance-shift detection. Many potential applications are foreseen for such sensors, among them highly sensitive detection in ultrasound and optoacoustic imaging. Traditionally, sensor interrogation is performed by tuning a narrow linewidth laser to the resonance wavelength. Despite the ubiquity of this method, its use has been mostly limited to lab conditions due to its vulnerability to environmental factors and the difficulty of multiplexing - a key factor in imaging applications. In this paper, we develop a new optical-resonator interrogation scheme based on wideband pulse interferometry, potentially capable of achieving high stability against environmental conditions without compromising sensitivity. Additionally, the method can enable multiplexing several sensors. The unique properties of the pulse-interferometry interrogation approach are studied theoretically and experimentally. Methods for noise reduction in the proposed scheme are presented and experimentally demonstrated, while the overall performance is validated for broadband optical detection of ultrasonic fields. The achieved sensitivity is equivalent to the theoretical limit of a 6 MHz narrow-line width laser, which is 40 times higher than what can be usually achieved by incoherent interferometry for the same optical resonator.

Quantitative analysis of sitagliptin using the (19)F-NMR method: a universal technique for fluorinated compound detection.

PubMed

Zhang, Fen-Fen; Jiang, Meng-Hong; Sun, Lin-Lin; Zheng, Feng; Dong, Lei; Shah, Vishva; Shen, Wen-Bin; Ding, Ya

2015-01-07

To expand the application scope of nuclear magnetic resonance (NMR) technology in quantitative analysis of pharmaceutical ingredients, (19)F nuclear magnetic resonance ((19)F-NMR) spectroscopy has been employed as a simple, rapid, and reproducible approach for the detection of a fluorine-containing model drug, sitagliptin phosphate monohydrate (STG). ciprofloxacin (Cipro) has been used as the internal standard (IS). Influential factors, including the relaxation delay time (d1) and pulse angle, impacting the accuracy and precision of spectral data are systematically optimized. Method validation has been carried out in terms of precision and intermediate precision, linearity, limit of detection (LOD) and limit of quantification (LOQ), robustness, and stability. To validate the reliability and feasibility of the (19)F-NMR technology in quantitative analysis of pharmaceutical analytes, the assay result has been compared with that of (1)H-NMR. The statistical F-test and student t-test at 95% confidence level indicate that there is no significant difference between these two methods. Due to the advantages of (19)F-NMR, such as higher resolution and suitability for biological samples, it can be used as a universal technology for the quantitative analysis of other fluorine-containing pharmaceuticals and analytes.

Optical Detection of Ultrasound in Photoacoustic Imaging

PubMed Central

Dong, Biqin; Sun, Cheng; Zhang, Hao F.

2017-01-01

Objective Photoacoustic (PA) imaging emerges as a unique tool to study biological samples based on optical absorption contrast. In PA imaging, piezoelectric transducers are commonly used to detect laser-induced ultrasonic waves. However, they typically lack adequate broadband sensitivity at ultrasonic frequency higher than 100 MHz while their bulky size and optically opaque nature cause technical difficulties in integrating PA imaging with conventional optical imaging modalities. To overcome these limitations, optical methods of ultrasound detection were developed and shown their unique applications in photoacoustic imaging. Methods We provide an overview of recent technological advances in optical methods of ultrasound detection and their applications in PA imaging. A general theoretical framework describing sensitivity, bandwidth, and angular responses of optical ultrasound detection is also introduced. Results Optical methods of ultrasound detection can provide improved detection angle and sensitivity over significantly extended bandwidth. In addition, its versatile variants also offer additional advantages, such as device miniaturization, optical transparency, mechanical flexibility, minimal electrical/mechanical crosstalk, and potential noncontact PA imaging. Conclusion The optical ultrasound detection methods discussed in this review and their future evolution may play an important role in photoacoustic imaging for biomedical study and clinical diagnosis. PMID:27608445

An ultra-small, multi-point, and multi-color photo-detection system with high sensitivity and high dynamic range.

PubMed

Anazawa, Takashi; Yamazaki, Motohiro

2017-12-05

Although multi-point, multi-color fluorescence-detection systems are widely used in various sciences, they would find wider applications if they are miniaturized. Accordingly, an ultra-small, four-emission-point and four-color fluorescence-detection system was developed. Its size (space between emission points and a detection plane) is 15 × 10 × 12 mm, which is three-orders-of-magnitude smaller than that of a conventional system. Fluorescence from four emission points with an interval of 1 mm on the same plane was respectively collimated by four lenses and split into four color fluxes by four dichroic mirrors. Then, a total of sixteen parallel color fluxes were directly input into an image sensor and simultaneously detected. The emission-point plane and the detection plane (the image-sensor surface) were parallel and separated by a distance of only 12 mm. The developed system was applied to four-capillary array electrophoresis and successfully achieved Sanger DNA sequencing. Moreover, compared with a conventional system, the developed system had equivalent high fluorescence-detection sensitivity (lower detection limit of 17 pM dROX) and 1.6-orders-of-magnitude higher dynamic range (4.3 orders of magnitude).

Application of surface plasmon resonance biosensor for the detection of Candida albicans

NASA Astrophysics Data System (ADS)

Yodmongkol, Sirasa; Thaweboon, Sroisiri; Thaweboon, Boonyanit; Puttharugsa, Chokchai; Sutapun, Boonsong; Amarit, Ratthasart; Somboonkaew, Armote; Srikhirin, Toemsak

2016-02-01

In this study, surface plasmon resonance imaging (SPR imaging) was developed for the detection of Candida albicans which is a causal agent of oral infection. The detection was based on the sandwich assay. The capture antibody was covalently immobilized on the mixed self assemble monolayers (SAMs). The ratio of mixed SAMs between 11-mercaptoundecanoic acid and 3-mercaptopropanol was varied to find the optimal ratio for use as a sensor surface. The results showed that the suitable surface for C. albicans detection was SAM of carboxylic (mixed SAMs 1:0), even though mixed SAMs 1:40 had a high detection signal in comparison to mixed SAMs 1:0, but the non-specific signal was higher. The detection limit was 107 cells/ml for direct detection, and was increased to 106 cells/ml with sandwich antibody. The use of polyclonal C. albicans antibody as capture and sandwich antibody showed good selectivity against the relevant oral bacteria including Escherichia coli, Streptococcus mutan, Staphylococcus aureus, β-streptococci, and Lactobacillus casei. SPR platform in this study could detect C. albicans from the mixed microbial suspension without requirement of skillful technician. This SPR imaging biosensor could be applied for Candida identification after cultivation.

Nanotechnology: a promising method for oral cancer detection and diagnosis.

PubMed

Chen, Xiao-Jie; Zhang, Xue-Qiong; Liu, Qi; Zhang, Jing; Zhou, Gang

2018-06-11

Oral cancer is a common and aggressive cancer with high morbidity, mortality, and recurrence rate globally. Early detection is of utmost importance for cancer prevention and disease management. Currently, tissue biopsy remains the gold standard for oral cancer diagnosis, but it is invasive, which may cause patient discomfort. The application of traditional noninvasive methods-such as vital staining, exfoliative cytology, and molecular imaging-is limited by insufficient sensitivity and specificity. Thus, there is an urgent need for exploring noninvasive, highly sensitive, and specific diagnostic techniques. Nano detection systems are known as new emerging noninvasive strategies that bring the detection sensitivity of biomarkers to nano-scale. Moreover, compared to current imaging contrast agents, nanoparticles are more biocompatible, easier to synthesize, and able to target specific surface molecules. Nanoparticles generate localized surface plasmon resonances at near-infrared wavelengths, providing higher image contrast and resolution. Therefore, using nano-based techniques can help clinicians to detect and better monitor diseases during different phases of oral malignancy. Here, we review the progress of nanotechnology-based methods in oral cancer detection and diagnosis.

A novel Laser Ion Mobility Spectrometer

NASA Astrophysics Data System (ADS)

Göbel, J.; Kessler, M.; Langmeier, A.

2009-05-01

IMS is a well know technology within the range of security based applications. Its main advantages lie in the simplicity of measurement, along with a fast and sensitive detection method. Contemporary technology often fails due to interference substances, in conjunction with saturation effects and a low dynamic detection range. High throughput facilities, such as airports, require the analysis of many samples at low detection limits within a very short timeframe. High detection reliability is a requirement for safe and secure operation. In our present work we developed a laser based ion-mobility-sensor which shows several advantages over known IMS sensor technology. The goal of our research was to increase the sensitivity compared to the range of 63Ni based instruments. This was achieved with an optimised geometric drift tube design and a pulsed UV laser system at an efficient intensity. In this intensity range multi-photon ionisation is possible, which leads to higher selectivity in the ion-formation process itself. After high speed capturing of detection samples, a custom designed pattern recognition software toolbox provides reliable auto-detection capability with a learning algorithm and a graphical user interface.

New calorimeters for space experiments: physics requirements and technological challenges

NASA Astrophysics Data System (ADS)

Marrocchesi, Pier Simone

2015-07-01

Direct measurements of charged cosmic radiation with instruments in Low Earth Orbit (LEO), or flying on balloons above the atmosphere, require the identification of the incident particle, the measurement of its energy and possibly the determination of its sign-of-charge. The latter information can be provided by a magnetic spectrometer together with a measurement of momentum. However, magnetic deflection in space experiments is at present limited to values of the Maximum Detectable Rigidity (MDR) hardly exceeding a few TV. Advanced calorimetric techniques are, at present, the only way to measure charged and neutral radiation at higher energies in the multi-TeV range. Despite their mass limitation, calorimeters may achieve a large geometric factor and provide an adequate proton background rejection factor, taking advantage of a fine granularity and imaging capabilities. In this lecture, after a brief introduction on electromagnetic and hadronic calorimetry, an innovative approach to the design of a space-borne, large acceptance, homogeneous calorimeter for the detection of high energy cosmic rays will be described.

Determination of furan levels in commercial samples of baby food from Brazil and preliminary risk assessment.

PubMed

Pavesi Arisseto, A; Vicente, E; De Figueiredo Toledo, M C

2010-08-01

Commercial baby food samples available on the Brazilian market (n = 31) were analysed for furan content using a gas chromatography-mass spectrometry method preceded by solid-phase microextraction. A limit of detection of 0.7 microg kg(-1), a limit of quantitation of 2.4 microg kg(-1), mean recoveries varying from 80% to 107%, and coefficients of variation ranging from 5.6% to 9.4% for repeatability and from 7.4% to 12.4% for within-laboratory reproducibility were obtained during an in-house validation. The levels of furan found in the samples were from not detected to 95.5 microg kg(-1). Samples containing vegetables and meat showed higher furan levels as compared with those containing only fruits. An exposure assessment showed furan intakes up to 2.4 microg kg(-1) body weight day(-1) (99th percentile) for babies fed exclusively with commercial baby foods. Margins of exposure obtained from intakes estimated in this work indicated a potential public health concern.

Building Practical Apertureless Scanning Near-Field Microscopy

NASA Astrophysics Data System (ADS)

Gungordu, M. Zeki

The fundamental objective of this study is to establish a functional, practical apertureless type scanning near-field optical microscope, and to figure out the working mechanism behind it. Whereas a far-field microscope can measure the propagating field's components, this gives us little information about the features of the sample. The resolution is limited to about half of the wavelength of the illuminating light. On the other hand, the a-SNOM system enables achieving non-propagating components of the field, which provides more details about the sample's features. It is really difficult to measure because the amplitude of this field decays exponentially when the tip is moved away from the sample. The sharpness of the tip is the only limitation for resolution of the a-SNOM system. Consequently, the sharp tips are achieved by using electrochemical etching, and these tips are used to detect near-field signal. Separating the weak a-SNOM system signals from the undesired background signal, the higher demodulation background suppression is utilized by lock-in detection.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Di, Zichao; Chen, Si; Hong, Young Pyo

X-ray fluorescence tomography is based on the detection of fluorescence x-ray photons produced following x-ray absorption while a specimen is rotated; it provides information on the 3D distribution of selected elements within a sample. One limitation in the quality of sample recovery is the separation of elemental signals due to the finite energy resolution of the detector. Another limitation is the effect of self-absorption, which can lead to inaccurate results with dense samples. To recover a higher quality elemental map, we combine x-ray fluorescence detection with a second data modality: conventional x-ray transmission tomography using absorption. By using these combinedmore » signals in a nonlinear optimization-based approach, we demonstrate the benefit of our algorithm on real experimental data and obtain an improved quantitative reconstruction of the spatial distribution of dominant elements in the sample. Furthermore, compared with single-modality inversion based on x-ray fluorescence alone, this joint inversion approach reduces ill-posedness and should result in improved elemental quantification and better correction of self-absorption.« less

Removal of Pharmaceutical and Personal Care Products (PPCPs) from Municipal Waste Water with Integrated Membrane Systems, MBR-RO/NF

PubMed Central

Wang, Yonggang; Wang, Xu; Li, Mingwei; Dong, Jing; Sun, Changhong; Chen, Guanyi

2018-01-01

This study focuses on the application of combining membrane bioreactor (MBR) treatment with reverse osmosis (RO) or nanofiltration (NF) membrane treatment for removal of pharmaceuticals and personal care products (PPCPs) in municipal wastewater. Twenty-seven PPCPs were measured in real influent with lowest average concentration being trimethoprim (7.12 ng/L) and the highest being caffeine (18.4 ng/L). The results suggest that the MBR system effectively removes the PPCPs with an efficiency of between 41.08% and 95.41%, and that the integrated membrane systems, MBR-RO/NF, can achieve even higher removal rates of above 95% for most of them. The results also suggest that, due to the differences in removal mechanisms of NF/RO membrane, differences of removal rates exist. In this study, the combination of MBR-NF resulted in the removal of 13 compounds to below detection limits and MBR-RO achieved even better results with removal of 20 compounds to below detection limits. PMID:29401723

Advances in ultrasensitive mass spectrometry of organic molecules.

PubMed

Kandiah, Mathivathani; Urban, Pawel L

2013-06-21

Ultrasensitive mass spectrometric analysis of organic molecules is important for various branches of chemistry, and other fields including physics, earth and environmental sciences, archaeology, biomedicine, and materials science. It finds applications--as an enabling tool--in systems biology, biological imaging, clinical analysis, and forensics. Although there are a number of technical obstacles associated with the analysis of samples by mass spectrometry at ultratrace level (for example analyte losses during sample preparation, insufficient sensitivity, ion suppression), several noteworthy developments have been made over the years. They include: sensitive ion sources, loss-free interfaces, ion optics components, efficient mass analyzers and detectors, as well as "smart" sample preparation strategies. Some of the mass spectrometric methods published to date can achieve sensitivity which is by several orders of magnitude higher than that of alternative approaches. Femto- and attomole level limits of detection are nowadays common, while zepto- and yoctomole level limits of detection have also been reported. We envision that the ultrasensitive mass spectrometric assays will soon contribute to new discoveries in bioscience and other areas.

Joint reconstruction of x-ray fluorescence and transmission tomography

PubMed Central

Di, Zichao Wendy; Chen, Si; Hong, Young Pyo; Jacobsen, Chris; Leyffer, Sven; Wild, Stefan M.

2017-01-01

X-ray fluorescence tomography is based on the detection of fluorescence x-ray photons produced following x-ray absorption while a specimen is rotated; it provides information on the 3D distribution of selected elements within a sample. One limitation in the quality of sample recovery is the separation of elemental signals due to the finite energy resolution of the detector. Another limitation is the effect of self-absorption, which can lead to inaccurate results with dense samples. To recover a higher quality elemental map, we combine x-ray fluorescence detection with a second data modality: conventional x-ray transmission tomography using absorption. By using these combined signals in a nonlinear optimization-based approach, we demonstrate the benefit of our algorithm on real experimental data and obtain an improved quantitative reconstruction of the spatial distribution of dominant elements in the sample. Compared with single-modality inversion based on x-ray fluorescence alone, this joint inversion approach reduces ill-posedness and should result in improved elemental quantification and better correction of self-absorption. PMID:28788848

Cavity-Enhanced Raman Spectroscopy of Natural Gas with Optical Feedback cw-Diode Lasers.

PubMed

Hippler, Michael

2015-08-04

We report on improvements made on our previously introduced technique of cavity-enhanced Raman spectroscopy (CERS) with optical feedback cw-diode lasers in the gas phase, including a new mode-matching procedure which keeps the laser in resonance with the optical cavity without inducing long-term frequency shifts of the laser, and using a new CCD camera with improved noise performance. With 10 mW of 636.2 nm diode laser excitation and 30 s integration time, cavity enhancement achieves noise-equivalent detection limits below 1 mbar at 1 bar total pressure, depending on Raman cross sections. Detection limits can be easily improved using higher power diodes. We further demonstrate a relevant analytical application of CERS, the multicomponent analysis of natural gas samples. Several spectroscopic features have been identified and characterized. CERS with low power diode lasers is suitable for online monitoring of natural gas mixtures with sensitivity and spectroscopic selectivity, including monitoring H2, H2S, N2, CO2, and alkanes.

Removal of Pharmaceutical and Personal Care Products (PPCPs) from Municipal Waste Water with Integrated Membrane Systems, MBR-RO/NF.

PubMed

Wang, Yonggang; Wang, Xu; Li, Mingwei; Dong, Jing; Sun, Changhong; Chen, Guanyi

2018-02-05

This study focuses on the application of combining membrane bioreactor (MBR) treatment with reverse osmosis (RO) or nanofiltration (NF) membrane treatment for removal of pharmaceuticals and personal care products (PPCPs) in municipal wastewater. Twenty-seven PPCPs were measured in real influent with lowest average concentration being trimethoprim (7.12 ng/L) and the highest being caffeine (18.4 ng/L). The results suggest that the MBR system effectively removes the PPCPs with an efficiency of between 41.08% and 95.41%, and that the integrated membrane systems, MBR-RO/NF, can achieve even higher removal rates of above 95% for most of them. The results also suggest that, due to the differences in removal mechanisms of NF/RO membrane, differences of removal rates exist. In this study, the combination of MBR-NF resulted in the removal of 13 compounds to below detection limits and MBR-RO achieved even better results with removal of 20 compounds to below detection limits.

Laser Diagnostics for Reacting Flows

DTIC Science & Technology

2010-01-11

noise characteristics of the diagnostic will be in the shot - noise limit , a fundamental limit of the LIF signal intensity... noise related to the discrete nature of photons. In the shot - noise limit , the fluctuation detection limit can be predicted using nVP B S f f  1...detection limit was shot - noise limited . Figure 2.2.3 illustrates the fluctuation detection limits for line LIF imaging. Figure 2.2.3a

Occurrence, distribution, and transport of pesticides, trace elements, and selected inorganic constituents into the Salton Sea Basin, California, 2001-2002

USGS Publications Warehouse

LeBlanc, Lawrence A.; Schroeder, Roy A.; Orlando, James L.; Kuivila, Kathyrn M.

2004-01-01

A study of pesticide distribution and transport within the Salton Sea Basin, California, was conducted from September 2001 to October 2002. Sampling for the study was done along transects for the three major rivers that flow into the Salton Sea Basin: the New and Alamo Rivers at the southern end of the basin and the Whitewater River at the northern end. Three stations were established on each river: an outlet station approximately 1 mile upstream of the river discharge, a near-shore station in the river delta, and off-shore station in the Salton Sea. Water and suspended and bed sediments were collected at each station in October 2001, March-April 2002, and September 2002, coinciding with peak pesticide applications in the fall and spring. Fourteen current-use pesticides were detected in the water column. Concentrations of dissolved pesticides typically decreased from the outlets to the sea in all three rivers, consistent with the off-shore transport of pesticides from the rivers to the sea. Dissolved concentrations ranged from the limits of detection to 151 nanograms per liter (ng/L); however, diazinon, eptam (EPTC), and malathion were detected at much higher concentrations (940?3,830 ng/L) at the New and Alamo River outlet and near-shore stations. Concentrations of carbaryl, dacthal, diazinon, and eptam were higher during the two fall sampling periods, whereas concentrations of atrazine, carbofuran, and trifluralin were higher during the spring. Current-use pesticides also were detected on suspended and bed sediments in concentrations ranging from method detection limits to 106 ng/g (nanograms per gram). Chlorpyrifos, dacthal, eptam, trifluralin, and DDE were the most frequently detected pesticides on sediments from all three rivers. The number and concentrations of pesticides associated with suspended sediments frequently were similar for the river outlet and near-shore sites, consistent with the downstream transport of sediment-associated pesticides out of the rivers. Seasonal trends in pesticide concentration were similar to those for dissolved concentrations in fall 2001 and spring 2002, but not in fall 2002. Generally, the pesticides detected in the suspended sediments were the same pesticides detected in the bed sediments, and concentrations were similar, especially at the Alamo River outlet site in spring 2002 and fall 2002. Pesticides generally were not detected in sediments from the off-shore sites; however, the samples from these sites also had greater incidences of matrix interference during analysis. Sediment-associated pesticide concentrations were above equilibrium in water, suggesting a bound fraction of sediment-associated pesticides that are resistant to desorption. Concentrations of trace elements and other inorganic constituents in suspended sediments collected during the fall 2001 followed expected trends with dilution of river-derived minerals owing to highly organic autochthonous production within the Salton Sea Basin. However, calculation of enrichment ratios provided evidence for the bioconcentration of several trace elements, notably selenium in the off-shore biota.

Calculation of the detection limits for radionuclides identified in gamma-ray spectra based on post-processing peak analysis results.

PubMed

Korun, M; Vodenik, B; Zorko, B

2018-03-01

A new method for calculating the detection limits of gamma-ray spectrometry measurements is presented. The method is applicable for gamma-ray emitters, irrespective of the influences of the peaked background, the origin of the background and the overlap with other peaks. It offers the opportunity for multi-gamma-ray emitters to calculate the common detection limit, corresponding to more peaks. The detection limit is calculated by approximating the dependence of the uncertainty in the indication on its value with a second-order polynomial. In this approach the relation between the input quantities and the detection limit are described by an explicit expression and can be easy investigated. The detection limit is calculated from the data usually provided by the reports of peak-analyzing programs: the peak areas and their uncertainties. As a result, the need to use individual channel contents for calculating the detection limit is bypassed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modeling and research of a space-based spacecraft infrared detection system.

PubMed

Li, Wenhao; Liu, Zhaohui; Mu, You; Yang, Rui; Zhang, Xing

2017-03-20

When a spacecraft is in orbit, it is almost impossible to check its working condition. Almost all payload would generate waste heat when working, which is usually ejected by a radiator. By observing the radiator, we can catch a glimpse of a spacecraft's inner information. A thorough model of a space-based infrared detection system is analyzed, taking the radiator into account, which, to the best of our knowledge, has seldom been considered. The calculation result shows that infrared radiation reflected by spacecraft is weak compared with the spacecraft's self-radiation in 8-12 μm, and the contrast ratio between the radiator and surrounding area could be the criterion for judging the working condition of a spacecraft. The limit of detection distance is also increased due the higher temperature of the radiator.

Behavioral and Health Outcomes for HIV+ Young Transgender Women Linked To and Engaged in Medical Care

PubMed Central

Matone, Meredith; Luan, Xianqun; Lee, Susan; Belzer, Marvin; Fernandez, Maria Isabel; Rubin, David

2016-01-01

Abstract We describe health and psychosocial outcomes of HIV+ young transgender women (YTW) engaged in care across the United States. When compared to other behaviorally infected youth (BIY), YTW reported higher rates of unemployment (25% vs. 19%), limited educational achievement (42% vs 13%), and suboptimal ART adherence (51% vs. 30%). There was no difference in likelihood of having a detectable viral load (38% vs. 39%) between groups. However, particular isolating psychosocial factors (unstable housing, depression, and lack of social support for attending appointments) increased predicted probability of viral detection to a greater extent among YTW that may have important health implications for this marginalized youth population. PMID:26789394

Advancing Precision Nuclear Medicine and Molecular Imaging for Lymphoma.

PubMed

Wright, Chadwick L; Maly, Joseph J; Zhang, Jun; Knopp, Michael V

2017-01-01

PET with fluorodeoxyglucose F 18 ( 18 F FDG-PET) is a meaningful biomarker for the detection, targeted biopsy, and treatment of lymphoma. This article reviews the evolution of 18 F FDG-PET as a putative biomarker for lymphoma and addresses the current capabilities, challenges, and opportunities to enable precision medicine practices for lymphoma. Precision nuclear medicine is driven by new imaging technologies and methodologies to more accurately detect malignant disease. Although quantitative assessment of response is limited, such technologies will enable a more precise metabolic mapping with much higher definition image detail and thus may make it a robust and valid quantitative response assessment methodology. Copyright © 2016 Elsevier Inc. All rights reserved.

Limits of linearity and detection for some drugs of abuse.

PubMed

Needleman, S B; Romberg, R W

1990-01-01

The limits of linearity (LOL) and detection (LOD) are important factors in establishing the reliability of an analytical procedure for accurately assaying drug concentrations in urine specimens. Multiple analyses of analyte over an extended range of concentrations provide a measure of the ability of the analytical procedure to correctly identify known quantities of drug in a biofluid matrix. Each of the seven drugs of abuse gives linear analytical responses from concentrations at or near their LOD to concentrations several-fold higher than those generally encountered in the drug screening laboratory. The upper LOL exceeds the Department of Navy (DON) cutoff values by factors of approximately 2 to 160. The LOD varies from 0.4 to 5.0% of the DON cutoff value for each drug. The limit of quantitation (LOQ) is calculated as the LOD + 7 SD. The range for LOL is greater for drugs analyzed with deuterated internal standards compared with those using conventional internal standards. For THC acid, cocaine, PCP, and morphine, LOLs are 8 to 160-fold greater than the defined cutoff concentrations. For the other drugs, the LOL's are only 2 to 4-fold greater than the defined cutoff concentrations.

Quantum state reconstruction and photon number statistics for low dimensional semiconductor opto-electronic devices

NASA Astrophysics Data System (ADS)

Böhm, Fabian; Grosse, Nicolai B.; Kolarczik, Mirco; Herzog, Bastian; Achtstein, Alexander; Owschimikow, Nina; Woggon, Ulrike

2017-09-01

Quantum state tomography and the reconstruction of the photon number distribution are techniques to extract the properties of a light field from measurements of its mean and fluctuations. These techniques are particularly useful when dealing with macroscopic or mesoscopic systems, where a description limited to the second order autocorrelation soon becomes inadequate. In particular, the emission of nonclassical light is expected from mesoscopic quantum dot systems strongly coupled to a cavity or in systems with large optical nonlinearities. We analyze the emission of a quantum dot-semiconductor optical amplifier system by quantifying the modifications of a femtosecond laser pulse propagating through the device. Using a balanced detection scheme in a self-heterodyning setup, we achieve precise measurements of the quadrature components and their fluctuations at the quantum noise limit1. We resolve the photon number distribution and the thermal-to-coherent evolution in the photon statistics of the emission. The interferometric detection achieves a high sensitivity in the few photon limit. From our data, we can also reconstruct the second order autocorrelation function with higher precision and time resolution compared with classical Hanbury Brown-Twiss experiments.

Visual and Plasmon Resonance Absorption Sensor for Adenosine Triphosphate Based on the High Affinity between Phosphate and Zr(IV)

PubMed Central

Qi, Wenjing; Liu, Zhongyuan; Zhang, Wei; Halawa, Mohamed Ibrahim; Xu, Guobao

2016-01-01

Zr(IV) can form phosphate and Zr(IV) (–PO32−–Zr4+–) complex owing to the high affinity between Zr(IV) with phosphate. Zr(IV) can induce the aggregation of gold nanoparticles (AuNPs), while adenosine triphosphate(ATP) can prevent Zr(IV)-induced aggregation of AuNPs. Herein, a visual and plasmon resonance absorption (PRA)sensor for ATP have been developed using AuNPs based on the high affinity between Zr(IV)with ATP. AuNPs get aggregated in the presence of certain concentrations of Zr(IV). After the addition of ATP, ATP reacts with Zr(IV) and prevents AuNPs from aggregation, enabling the detection of ATP. Because of the fast interaction of ATP with Zr(IV), ATP can be detected with a detection limit of 0.5 μM within 2 min by the naked eye. Moreover, ATP can be detected by the PRA technique with higher sensitivity. The A520nm/A650nm values in PRA spectra increase linearly with the concentrations of ATP from 0.1 μM to 15 μM (r = 0.9945) with a detection limit of 28 nM. The proposed visual and PRA sensor exhibit good selectivity against adenosine, adenosine monophosphate, guanosine triphosphate, cytidine triphosphate and uridine triphosphate. The recoveries for the analysis of ATP in synthetic samples range from 95.3% to 102.0%. Therefore, the proposed novel sensor for ATP is promising for real-time or on-site detection of ATP. PMID:27754349

Levamisole: a Common Adulterant in Cocaine Street Samples Hindering Electrochemical Detection of Cocaine.

PubMed

de Jong, Mats; Florea, Anca; Vries, Anne-Mare de; van Nuijs, Alexander L N; Covaci, Adrian; Van Durme, Filip; Martins, José C; Samyn, Nele; De Wael, Karolien

2018-04-17

The present work investigates the electrochemical determination of cocaine in the presence of levamisole, one of the most common adulterants found in cocaine street samples. Levamisole misleads cocaine color tests, giving a blue color (positive test) even in the absence of cocaine. Moreover, the electrochemical detection of cocaine is also affected by the presence of levamisole, with a suppression of the oxidation signal of cocaine. When levamisole is present in the sample in ratios higher than 1:1, the cocaine signal is no longer detected, thus leading to false negative results. Mass spectrometry and nuclear magnetic resonance were used to investigate if the signal suppression is due to the formation of a complex between cocaine and levamisole in bulk solution. Strategies to eliminate this suppressing effect are further suggested in this manuscript. In a first approach, the increase of the pH of the sample solution from pH 7 to pH 12 allowed the voltammetric determination of cocaine in the presence of levamisole in a concentration range from 10 to 5000 μM at nonmodified graphite disposable electrodes with a detection limit of 5 μM. In a second approach, the graphite electrode was cathodically pretreated, resulting in the presence of oxidation peaks of both cocaine and levamisole, with a detection limit for cocaine of 3 μM over the linear range of concentrations from 10 to 2500 μM. Both these strategies have been successfully applied for the simultaneous detection of cocaine and levamisole in three street samples on unmodified graphite disposable electrodes.

Feasibility study of 235U and 239Pu characterization in radioactive waste drums using neutron-induced fission delayed gamma rays

NASA Astrophysics Data System (ADS)

Nicol, T.; Pérot, B.; Carasco, C.; Brackx, E.; Mariani, A.; Passard, C.; Mauerhofer, E.; Collot, J.

2016-10-01

This paper reports a feasibility study of 235U and 239Pu characterization in 225 L bituminized waste drums or 200 L concrete waste drums, by detecting delayed fission gamma rays between the pulses of a deuterium-tritium neutron generator. The delayed gamma yields were first measured with bare samples of 235U and 239Pu in REGAIN, a facility dedicated to the assay of 118 L waste drums by Prompt Gamma Neutron Activation Analysis (PGNAA) at CEA Cadarache, France. Detectability in the waste drums is then assessed using the MCNPX model of MEDINA (Multi Element Detection based on Instrumental Neutron Activation), another PGNAA cell dedicated to 200 L drums at FZJ, Germany. For the bituminized waste drum, performances are severely hampered by the high gamma background due to 137Cs, which requires the use of collimator and shield to avoid electronics saturation, these elements being very penalizing for the detection of the weak delayed gamma signal. However, for lower activity concrete drums, detection limits range from 10 to 290 g of 235U or 239Pu, depending on the delayed gamma rays of interest. These detection limits have been determined by using MCNPX to calculate the delayed gamma useful signal, and by measuring the experimental gamma background in MEDINA with a 200 L concrete drum mock-up. The performances could be significantly improved by using a higher interrogating neutron emission and an optimized experimental setup, which would allow characterizing nuclear materials in a wide range of low and medium activity waste packages.

Multiple Hotspot Mutations Scanning by Single Droplet Digital PCR.

PubMed

Decraene, Charles; Silveira, Amanda B; Bidard, François-Clément; Vallée, Audrey; Michel, Marc; Melaabi, Samia; Vincent-Salomon, Anne; Saliou, Adrien; Houy, Alexandre; Milder, Maud; Lantz, Olivier; Ychou, Marc; Denis, Marc G; Pierga, Jean-Yves; Stern, Marc-Henri; Proudhon, Charlotte

2018-02-01

Progress in the liquid biopsy field, combined with the development of droplet digital PCR (ddPCR), has enabled noninvasive monitoring of mutations with high detection accuracy. However, current assays detect a restricted number of mutations per reaction. ddPCR is a recognized method for detecting alterations previously characterized in tumor tissues, but its use as a discovery tool when the mutation is unknown a priori remains limited. We established 2 ddPCR assays detecting all genomic alterations within KRAS exon 2 and EGFR exon 19 mutation hotspots, which are of clinical importance in colorectal and lung cancer, with use of a unique pair of TaqMan ® oligoprobes. The KRAS assay scanned for the 7 most common mutations in codons 12/13 but also all other mutations found in that region. The EGFR assay screened for all in-frame deletions of exon 19, which are frequent EGFR-activating events. The KRAS and EGFR assays were highly specific and both reached a limit of detection of <0.1% in mutant allele frequency. We further validated their performance on multiple plasma and formalin-fixed and paraffin-embedded tumor samples harboring a panel of different KRAS or EGFR mutations. This method presents the advantage of detecting a higher number of mutations with single-reaction ddPCRs while consuming a minimum of patient sample. This is particularly useful in the context of liquid biopsy because the amount of circulating tumor DNA is often low. This method should be useful as a discovery tool when the tumor tissue is unavailable or to monitor disease during therapy. © 2017 American Association for Clinical Chemistry.

A turn-on near-infrared fluorescent chemosensor for selective detection of lead ions based on a fluorophore-gold nanoparticle assembly.

PubMed

Wang, Shaozhen; Sun, Junyong; Gao, Feng

2015-06-21

A turn-on fluorescent chemosensor of Pb(2+) in the near-infrared (NIR) region, which is based on the Pb(2+)-tuned restored fluorescence of a weakly fluorescent fluorophore-gold nanoparticle (AuNPs) assembly, has been reported. In this fluorophore-AuNP assembly, NIR fluorescent dye brilliant cresyl blue (BCB) molecules act as fluorophores and are used for signal transduction of fluorescence, while AuNPs act as quenchers to quench the nearby fluorescent BCB molecules via electron transfer. In the presence of Pb(2+), fluorescent BCB molecules detached from AuNPs and restored their fluorescence due to the formation of a chelating complex between Pb(2+) and glutathione confined on AuNPs. Under the optimal conditions, the present BCB-AuNP assembly is capable of detecting Pb(2+) with a concentration ranging from 7.5 × 10(-10) to 1 × 10(-8) mol L(-1) (0.16-2.1 ng mL(-1)) and a detection limit of 0.51 nM (0.11 ng mL(-1)). The present BCB-AuNP assembly can be used in aqueous media for the determination of Pb(2+) unlike common organic fluorescent reagents, and also shows advantages of NIR fluorescence spectrophotometry such as less interference, lower detection limit, and higher sensitivity. Moreover, the present method was successfully applied for the detection of Pb(2+) in water samples with satisfactory results.

QCM-nanomagnetic beads biosensor for lead ion detection.

PubMed

Zhang, Qingli; Cui, Haixia; Xiong, Xingliang; Chen, Jun; Wang, Ying; Shen, Jia; Luo, Yiting; Chen, Longcong

2018-01-15

As lead poses a serious threat to humans even in small amounts, all kinds of lead detection sensors with high sensitivity and selectivity are being constantly improved and put forward. In this report, a novel, simple and label-free quartz crystal microbalance (QCM) biosensor is proposed for detecting lead ions (Pb 2+ ). The biosensor takes full advantage of the high specificity of GR-5 DNAzyme to Pb 2+ and the high sensitivity of QCM. In particular, nanomagnetic beads (NMBs) are used as a novel and effective mean of signal amplification in the biosensor because of their mass and their ability to enhance the inductive effect, which are very beneficial for both higher sensitivity and a lower detection limit. In practice, GR-5 DNAzyme, innovatively combined with NMBs, was modified on the gold electrode of the QCM through gold-sulfur self-assembly. When the electrode was exposed to Pb 2+ solution, DNAzyme was severed into two parts at the RNA site (rA), along with the release of NMBs, which caused a great increase in frequency shift of the QCM electrode. Finally, a perfect linear correlation between the logarithm of Pb 2+ concentration and the change in frequency was obtained from 1 pM to 50 nM, with a detection limit as low as 0.3 pM. Moreover, the biosensor shows both an average recovery of 97 ± 6% in a drinking water sample and an excellent specificity for Pb 2+ compared with other metal ions.

Detection of Toxoplasma oocysts from soil by modified sucrose flotation and PCR methods.

PubMed

Matsuo, Junji; Kimura, Daisuke; Rai, Shiba Kumar; Uga, Shoji

2004-06-01

A detection method of Toxoplasma gondii oocysts from soil was evaluated using the sucrose flotation technique with modification involving addition of 0.1% gelatin into washing and floating solutions. PCR was performed on untreated samples and after treatment with polyvinylpyrrolidone (PVP), heating and cooling, and NaCl. The addition of gelatin in the sucrose solution yielded a higher number of oocysts. A very thin band was observed when DNA extract was diluted to 1:1024, indicating the presence of PCR inhibitor in the soil. PCR performed on untreated DNA, on PVP-treated, and on PVP-treated with heating and cooling without added bovine serum albumin (BSA) showed a band only at higher dilutions (1:1024 and 1:512) but at a much lower dilution (1:8) with BSA. In contrast, DNA treated with all three agents showed a band at a much lower dilution (1:64), even without added BSA, and no dilution was required when BSA was added. The PCR inhibitors present in the soil were removed by employing various treatment procedures during DNA extraction, and BSA in PCR. Furthermore, the detection limit with the method was 1 oocyst/g of soil, indicating that this method is useful in epidemiological studies.

A facile one-pot preparation of Co3O4/g-C3N4 heterojunctions with excellent electrocatalytic activity for the detection of environmental phenolic hormones

NASA Astrophysics Data System (ADS)

Sun, Yanjuan; Jiang, Jizhou; Liu, Yi; Wu, Shengli; Zou, Jing

2018-02-01

The Co3O4/g-C3N4 heterojunctions were prepared by a facile one-pot thermal decomposition technique. Compared with g-C3N4, it was found that Co3O4/g-C3N4 heterojunctions possessed a higher Brunner-Emmet-Teller (BET) surface area, which was beneficial to the diffusion of aim molecules on the electrode surfaces. And the optimal Co3O4/g-C3N4 heterojunctions exhibited a narrower band gap and a higher donor density, resulting in an excellent electrocatalytic activity for environmental phenolic hormones. Moreover, the Co3O4/g-C3N4 heterojunctions were used for the electrochemical sensing of environmental phenolic hormones such as bisphenol A, pentachlorophenol, p-nitrophenol and octylphenol. All detection ranges reached three orders of magnitude, showing a lower limit of detection of 10-9 mol L-1. So, sensitivity and accurate determination of environmental phenolic hormones in real water samples may use this Co3O4/g-C3N4 heterojunctions modified electrode.

Orally administered DTPA penta-ethyl ester for the decorporation of inhaled 241Am

PubMed Central

Sueda, Katsuhiko; Sadgrove, Matthew P.; Huckle, James E.; Leed, Marina G. D.; Weber, Waylon M.; Doyle-Eisele, Melanie; Guilmette, Raymond A.; Jay, Michael

2014-01-01

Diethylenetriaminepentaacetic acid (DTPA) is an effective decorporation agent to facilitate the elimination of radionuclides from the body, but its permeability-limited oral bioavailability limits its utility in mass-casualty emergencies. To overcome this limitation, a prodrug strategy using the penta-ethyl ester form of DTPA is under investigation. Pharmacokinetic and biodistribution studies were conducted in rats by orally administering [14C]DTPA penta-ethyl ester, and this prodrug and its hydrolysis products were analyzed as a single entity. Compared to a previous reporting of intravenously administered DTPA, the oral administration of this prodrug resulted in a sustained plasma concentration profile with higher plasma exposure and lower clearance. An assessment of the urine composition revealed that the bioactivation was extensive but incomplete, with no detectable levels of the penta- or tetra-ester forms. Tissue distribution at 12 h was limited, with approximately 73% of the administered dose being associated with the gastrointestinal tract. In the efficacy study, rats were exposed to aerosols of 241Am nitrate before receiving a single oral treatment of the prodrug. The urinary excretion of 241Am was found to be 19% higher than with the control. Consistent with prior reports of DTPA, the prodrug was most effective when the treatment delays were minimized. PMID:24619514

To See or Not to See: Investigating Detectability of Ganges River Dolphins Using a Combined Visual-Acoustic Survey

PubMed Central

Richman, Nadia I.; Gibbons, James M.; Turvey, Samuel T.; Akamatsu, Tomonari; Ahmed, Benazir; Mahabub, Emile; Smith, Brian D.; Jones, Julia P. G.

2014-01-01

Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring. PMID:24805782

To see or not to see: investigating detectability of Ganges River dolphins using a combined visual-acoustic survey.

PubMed

Richman, Nadia I; Gibbons, James M; Turvey, Samuel T; Akamatsu, Tomonari; Ahmed, Benazir; Mahabub, Emile; Smith, Brian D; Jones, Julia P G

2014-01-01

Detection of animals during visual surveys is rarely perfect or constant, and failure to account for imperfect detectability affects the accuracy of abundance estimates. Freshwater cetaceans are among the most threatened group of mammals, and visual surveys are a commonly employed method for estimating population size despite concerns over imperfect and unquantified detectability. We used a combined visual-acoustic survey to estimate detectability of Ganges River dolphins (Platanista gangetica gangetica) in four waterways of southern Bangladesh. The combined visual-acoustic survey resulted in consistently higher detectability than a single observer-team visual survey, thereby improving power to detect trends. Visual detectability was particularly low for dolphins close to meanders where these habitat features temporarily block the view of the preceding river surface. This systematic bias in detectability during visual-only surveys may lead researchers to underestimate the importance of heavily meandering river reaches. Although the benefits of acoustic surveys are increasingly recognised for marine cetaceans, they have not been widely used for monitoring abundance of freshwater cetaceans due to perceived costs and technical skill requirements. We show that acoustic surveys are in fact a relatively cost-effective approach for surveying freshwater cetaceans, once it is acknowledged that methods that do not account for imperfect detectability are of limited value for monitoring.

Streak Imaging Flow Cytometer for Rare Cell Analysis.

PubMed

Balsam, Joshua; Bruck, Hugh Alan; Ossandon, Miguel; Prickril, Ben; Rasooly, Avraham

2017-01-01

There is a need for simple and affordable techniques for cytology for clinical applications, especially for point-of-care (POC) medical diagnostics in resource-poor settings. However, this often requires adapting expensive and complex laboratory-based techniques that often require significant power and are too massive to transport easily. One such technique is flow cytometry, which has great potential for modification due to the simplicity of the principle of optical tracking of cells. However, it is limited in that regard due to the flow focusing technique used to isolate cells for optical detection. This technique inherently reduces the flow rate and is therefore unsuitable for rapid detection of rare cells which require large volume for analysis.To address these limitations, we developed a low-cost, mobile flow cytometer based on streak imaging. In our new configuration we utilize a simple webcam for optical detection over a large area associated with a wide-field flow cell. The new flow cell is capable of larger volume and higher throughput fluorescence detection of rare cells than the flow cells with hydrodynamic focusing used in conventional flow cytometry. The webcam is an inexpensive, commercially available system, and for fluorescence analysis we use a 1 W 450 nm blue laser to excite Syto-9 stained cells with emission at 535 nm. We were able to detect low concentrations of stained cells at high flow rates of 10 mL/min, which is suitable for rapidly analyzing larger specimen volumes to detect rare cells at appropriate concentration levels. The new rapid detection capabilities, combined with the simplicity and low cost of this device, suggest a potential for clinical POC flow cytometry in resource-poor settings associated with global health.

Quasars with P v broad absorption in BOSS data release 9

NASA Astrophysics Data System (ADS)

Capellupo, D. M.; Hamann, F.; Herbst, H.; Brandt, W. N.; Ge, J.; Pâris, I.; Petitjean, P.; Schneider, D. P.; Streblyanska, A.; York, D.

2017-07-01

Broad absorption lines (BALs) found in a significant fraction of quasar spectra identify high-velocity outflows that might be present in all quasars and could be a major factor in feedback to galaxy evolution. Understanding the nature of these flows requires further constraints on their physical properties, including their column densities, for which well-studied BALs, such as C IV λλ1548,1551, typically provide only a lower limit because of saturation effects. Low-abundance lines, such as P v λλ1118,1128, indicate large column densities, implying that outflows more powerful than measurements of C IV alone would indicate. We search through a sample of 2694 BAL quasars from the Sloan Digital Sky Survey III/Baryon Oscillation Spectroscopic Survey data release 9 quasar catalogue for such absorption, and we identify 81 'definite' and 86 'probable' detections of P v broad absorption, yielding a firm lower limit of 3.0-6.2 per cent for the incidence of such absorption among BAL quasars. The P v-detected quasars tend to have stronger C IV and Si IV absorption, as well as a higher incidence of LoBAL absorption, than the overall BAL quasar population. Many of the P v-detected quasars have C IV troughs that do not reach zero intensity (at velocities where P v is detected), confirming that the outflow gas only partially covers the UV continuum source. P v appears significantly in a composite spectrum of non-P v-detected BAL quasars, indicating that P v absorption (and large column densities) is much more common than indicated by our search results. Our sample of P v detections significantly increases the number of known P v detections, providing opportunities for follow-up studies to better understand BAL outflow energetics.

Determination of free and deconjugated testosterone and epitestosterone in urine using SPME and LC-MS/MS.

PubMed

Zhan, Yanwei; Musteata, Florin M; Basset, Fabien A; Pawliszyn, Janusz

2011-01-01

A thin sheet of polydimethylsilosane membrane was used as an extraction phase for solid-phase microextraction. Compared with fiber or rod solid-phase microextraction geometries, the thin film exhibited much higher extraction capacity without sacrificing extraction time due to its higher area-to-volume ratio. The analytical method involved direct extraction of unconjugated testosterone (T) and epitestosterone (ET) followed by separation on a C18 column and detection by selected reaction monitoring in positive ionization mode. The limit of detection was 1 ng/l for both T and ET. After method validation, free (unconjugated) T and ET were extracted and quantified in real samples. Since T and ET are extensively metabolized, the proposed method was also applied to extract the steroids after enzymatic deconjugation of urinary-excreted steroid glucuronides. The proposed method allows quantification of both conjugated and unconjugated steroids, and revealed that there was a change in the ratio of T to ET after enzymatic deconjugation, indicating different rates of metabolism.

Highly sensitive MoS2 photodetectors with graphene contacts

NASA Astrophysics Data System (ADS)

Han, Peize; St. Marie, Luke; Wang, Qing X.; Quirk, Nicholas; El Fatimy, Abdel; Ishigami, Masahiro; Barbara, Paola

2018-05-01

Two-dimensional materials such as graphene and transition metal dichalcogenides (TMDs) are ideal candidates to create ultra-thin electronics suitable for flexible substrates. Although optoelectronic devices based on TMDs have demonstrated remarkable performance, scalability is still a significant issue. Most devices are created using techniques that are not suitable for mass production, such as mechanical exfoliation of monolayer flakes and patterning by electron-beam lithography. Here we show that large-area MoS2 grown by chemical vapor deposition and patterned by photolithography yields highly sensitive photodetectors, with record shot-noise-limited detectivities of 8.7 × 1014 Jones in ambient condition and even higher when sealed with a protective layer. These detectivity values are higher than the highest values reported for photodetectors based on exfoliated MoS2. We study MoS2 devices with gold electrodes and graphene electrodes. The devices with graphene electrodes have a tunable band alignment and are especially attractive for scalable ultra-thin flexible optoelectronics.

Highly sensitive MoS2 photodetectors with graphene contacts.

PubMed

Han, Peize; St Marie, Luke; Wang, Qing X; Quirk, Nicholas; El Fatimy, Abdel; Ishigami, Masahiro; Barbara, Paola

2018-05-18

Two-dimensional materials such as graphene and transition metal dichalcogenides (TMDs) are ideal candidates to create ultra-thin electronics suitable for flexible substrates. Although optoelectronic devices based on TMDs have demonstrated remarkable performance, scalability is still a significant issue. Most devices are created using techniques that are not suitable for mass production, such as mechanical exfoliation of monolayer flakes and patterning by electron-beam lithography. Here we show that large-area MoS 2 grown by chemical vapor deposition and patterned by photolithography yields highly sensitive photodetectors, with record shot-noise-limited detectivities of 8.7 × 10 14 Jones in ambient condition and even higher when sealed with a protective layer. These detectivity values are higher than the highest values reported for photodetectors based on exfoliated MoS 2 . We study MoS 2 devices with gold electrodes and graphene electrodes. The devices with graphene electrodes have a tunable band alignment and are especially attractive for scalable ultra-thin flexible optoelectronics.

Evaluation of SDS depletion using an affinity spin column and IMS-MS detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hengel, Shawna M.; Floyd, Erica A.; Baker, Erin Shammel

2012-11-01

While the use of detergents is necessary for a variety of protein isolation preparation protocols, often prior to mass spectral (MS) analysis, they are not compatible with MS analysis due to ion suppression and adduct formation. This manuscript describes optimization of detergent removal, using commercially available SDS depletion spin columns containing an affinity resin, providing for both increased protein recovery and thorough SDS removal. Ion mobility spectrometry coupled with mass spectrometry (IMS-MS) allowed for a concurrent analysis of both analyte and detergent. In the case of both proteins and peptides, higher detergent concentrations than previously reported provided an increase ofmore » sample recovery; however there was a limit as SDS was detected by IMS-MS at higher levels of SDS indicating incomplete detergent depletion. The results also suggest optimal conditions for SDS removal are dependent on the sample concentration. Overall, this study provides a useful guide for proteomic studies where SDS is required for efficient sample preparation.« less

Nest site selection by Kentish plover suggests a trade-off between nest-crypsis and predator detection strategies.

PubMed

Gómez-Serrano, Miguel Ángel; López-López, Pascual

2014-01-01

Predation is one of the main causes of adult mortality and breeding failure for ground-nesting birds. Micro-habitat structure around nests plays a critical role in minimizing predation risk. Plovers nest in sites with little vegetation cover to maximize the incubating adult visibility, but many studies suggest a trade-off between nest-crypsis and predator detection strategies. However, this trade-off has not been explored in detail because methods used so far do not allow estimating the visibility with regards to critical factors such as slope or plant permeability to vision. Here, we tested the hypothesis that Kentish plovers select exposed sites according to a predator detection strategy, and the hypothesis that more concealed nests survive longer according to a crypsis strategy. To this end, we obtained an accurate estimation of the incubating adult's field of vision through a custom built inverted periscope. Our results showed that plovers selected nest sites with higher visibility than control points randomly selected with regards to humans and dogs, although nests located in sites with higher vegetation cover survived longer. In addition, the flushing distance (i.e., the distance at which incubating adults leave the nest when they detect a potential predator) decreased with vegetation cover. Consequently, the advantages of concealing the nest were limited by the ability to detect predators, thus indirectly supporting the existence of the trade-off between crypsis and predator detection. Finally, human disturbance also constrained nest choice, forcing plovers to move to inland sites that were less suitable because of higher vegetation cover, and modulated flushing behavior, since plovers that were habituated to humans left their nests closer to potential predators. This constraint on the width of suitable breeding habitat is particularly relevant for the conservation of Kentish Plover in sand beaches, especially under the current context of coastal regression and increase of recreational activities.

Nest Site Selection by Kentish Plover Suggests a Trade-Off between Nest-Crypsis and Predator Detection Strategies

PubMed Central

Gómez-Serrano, Miguel Ángel; López-López, Pascual

2014-01-01

Predation is one of the main causes of adult mortality and breeding failure for ground-nesting birds. Micro-habitat structure around nests plays a critical role in minimizing predation risk. Plovers nest in sites with little vegetation cover to maximize the incubating adult visibility, but many studies suggest a trade-off between nest-crypsis and predator detection strategies. However, this trade-off has not been explored in detail because methods used so far do not allow estimating the visibility with regards to critical factors such as slope or plant permeability to vision. Here, we tested the hypothesis that Kentish plovers select exposed sites according to a predator detection strategy, and the hypothesis that more concealed nests survive longer according to a crypsis strategy. To this end, we obtained an accurate estimation of the incubating adult's field of vision through a custom built inverted periscope. Our results showed that plovers selected nest sites with higher visibility than control points randomly selected with regards to humans and dogs, although nests located in sites with higher vegetation cover survived longer. In addition, the flushing distance (i.e., the distance at which incubating adults leave the nest when they detect a potential predator) decreased with vegetation cover. Consequently, the advantages of concealing the nest were limited by the ability to detect predators, thus indirectly supporting the existence of the trade-off between crypsis and predator detection. Finally, human disturbance also constrained nest choice, forcing plovers to move to inland sites that were less suitable because of higher vegetation cover, and modulated flushing behavior, since plovers that were habituated to humans left their nests closer to potential predators. This constraint on the width of suitable breeding habitat is particularly relevant for the conservation of Kentish Plover in sand beaches, especially under the current context of coastal regression and increase of recreational activities. PMID:25208045

Occurrence and distribution of pesticides and volatile organic compounds in ground water and surface water in Central Arizona Basins, 1996-98, and their relation to land use

USGS Publications Warehouse

Gellenbeck, Dorinda J.; Anning, David W.

2002-01-01

Samples of ground water and surface water from the Sierra Vista subbasin, the Upper Santa Cruz Basin, and the West Salt River Valley were collected and analyzed to determine the occurrence and distribution of pesticides and volatile organic compounds in central Arizona. The study was done during 1996-98 within the Central Arizona Basins study unit of the National Water-Quality Assessment program. This study included 121 wells and 4 surface-water sites in the 3 basins and the analyses of samples from 4 sites along the Santa Cruz River that were part of a separate study. Samples were collected from 121 wells and 3 surface-water sites for pesticide analyses, and samples were collected from 109 wells and 3 surface-water sites for volatile organic compound analyses. Certain pesticides detected in ground water and surface water can be related specifically to agricultural or urban uses; others can be related to multiple land uses. Effects from historical agriculture are made evident by detections of DDE in ground-water and surface-water samples collected in the West Salt River Valley and detections of atrazine and deethylatrazine in the ground water in the Upper Santa Cruz Basin. Effects from present agriculture are evident in the seasonal variability in concentrations of pre-emergent pesticides in surface-water samples from the West Salt River Valley. Several detections of DDE and dieldrin in surface water were higher than established water-quality limits. Effects of urban land use are made evident by detections of volatile organic compounds in ground water and surface water from the West Salt River Valley. Detections of volatile organic compounds in surface water from the Santa Cruz River near Nogales, Arizona, also are indications of the effects of urban land use. One detection of tetrachloroethene in ground water was higher than established water-quality limits. Water reuse is an important conservation technique in the Southwest; however, the reuse of water provides a transport mechanism for pesticides and volatile organic compounds to reach areas that are not normally affected by manmade compounds from specific land-use activities. The most complex mixture of pesticides and volatile organic compounds is in the West Salt River Valley and is the result of water-management practices and the combination of land uses in this basin throughout history.

Developments and Applications of Electrophoresis and Small Molecule Laser Desorption Ionization Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Hui

2007-01-01

Ultra-sensitive native fluorescence detection of proteins with miniaturized one- and two-dimensional polyacrylamide gel electrophoresis was achieved with laser side-entry excitation, which provides both high excitation power and low background level. The detection limit for R-phycoerythrin protein spots in 1-D SDS-PAGE was as low as 15 fg, which corresponds to 40 thousand molecules only. The average detection limit of six standard native proteins was 5 pg per band and the dynamic range spanned more than 3 orders of magnitude. Approximately 150 protein spots from 30 ng of total Escherichia coli extraction were detected on a 0.8 cm x 1 cm gelmore » in two-dimensional separation. Estrogen-DNA adducts as 4-OHE 1(E 2)-1-N3Ade and 4-OHEI(E 2)-2-NacCys were hypothesized as early risk assessment of prostate and breast cancers. Capillary electrophoresis, luminescence/absorption spectroscopy and LC-MS were used to characterize and detect these adducts. Monoclonal antibodies against each individual adduct were developed and used to enrich such compounds from urine samples of prostate and breast cancer patients as well as healthy people. Adduct 4-OHE 1-1-N3Ade was detected at much higher level in urine from subjects with prostate cancer patients compared to healthy males. The same adduct and 4-OHEI-2-NacCys were also detected at a much higher level in urine from a woman with breast carcinoma than samples from healthy controls. These two DNA adducts may serve as novel biomarkers for early diagnostic of cancers. The adsorption properties of R-phycoerythrin (RPE), on the fused-silica surface were studied using capillary electrophoresis (CE) and single molecule spectroscopy. The band shapes and migration times were measured in CE. Adsorption and desorption events were recorded at the single-molecule level by imaging of the evanescent-field layer using total internal reflection. The adsorbed RPE molecules on the fused-silica prism surface were counted with confidence based on Imagej software. The capacity factor and desorption rate were estimated from the counting results. The mobility-based adsorption isotherms were constructed from both computer simulations and experiments to determine the capacity factor.« less

Limits of detection and decision. Part 4

NASA Astrophysics Data System (ADS)

Voigtman, E.

2008-02-01

Probability density functions (PDFs) have been derived for a number of commonly used limit of detection definitions, including several variants of the Relative Standard Deviation of the Background-Background Equivalent Concentration (RSDB-BEC) method, for a simple linear chemical measurement system (CMS) having homoscedastic, Gaussian measurement noise and using ordinary least squares (OLS) processing. All of these detection limit definitions serve as both decision and detection limits, thereby implicitly resulting in 50% rates of Type 2 errors. It has been demonstrated that these are closely related to Currie decision limits, if the coverage factor, k, is properly defined, and that all of the PDFs are scaled reciprocals of noncentral t variates. All of the detection limits have well-defined upper and lower limits, thereby resulting in finite moments and confidence limits, and the problem of estimating the noncentrality parameter has been addressed. As in Parts 1-3, extensive Monte Carlo simulations were performed and all the simulation results were found to be in excellent agreement with the derived theoretical expressions. Specific recommendations for harmonization of detection limit methodology have also been made.

Recent trends in high spin sensitivity magnetic resonance

NASA Astrophysics Data System (ADS)

Blank, Aharon; Twig, Ygal; Ishay, Yakir

2017-07-01

Magnetic resonance is a very powerful methodology that has been employed successfully in many applications for about 70 years now, resulting in a wealth of scientific, technological, and diagnostic data. Despite its many advantages, one major drawback of magnetic resonance is its relatively poor sensitivity and, as a consequence, its bad spatial resolution when examining heterogeneous samples. Contemporary science and technology often make use of very small amounts of material and examine heterogeneity on a very small length scale, both of which are well beyond the current capabilities of conventional magnetic resonance. It is therefore very important to significantly improve both the sensitivity and the spatial resolution of magnetic resonance techniques. The quest for higher sensitivity led in recent years to the development of many alternative detection techniques that seem to rival and challenge the conventional ;old-fashioned; induction-detection approach. The aim of this manuscript is to briefly review recent advances in the field, and to provide a quantitative as well as qualitative comparison between various detection methods with an eye to future potential advances and developments. We first offer a common definition of sensitivity in magnetic resonance to enable proper quantitative comparisons between various detection methods. Following that, up-to-date information about the sensitivity capabilities of the leading recently-developed detection approaches in magnetic resonance is provided, accompanied by a critical comparison between them and induction detection. Our conclusion from this comparison is that induction detection is still indispensable, and as such, it is very important to look for ways to significantly improve it. To do so, we provide expressions for the sensitivity of induction-detection, derived from both classical and quantum mechanics, that identify its main limiting factors. Examples from current literature, as well as a description of new ideas, show how these limiting factors can be mitigated to significantly improve the sensitivity of induction detection. Finally, we outline some directions for the possible applications of high-sensitivity induction detection in the field of electron spin resonance.

Simultaneous Determination of Preservatives in Dairy Products by HPLC and Chemometric Analysis

PubMed Central

Zamani Mazdeh, Fatemeh; Sasanfar, Sima; Chalipour, Anita; Pirhadi, Elham; Yahyapour, Ghazal; Mohammadi, Armin; Rostami, Akram; Amini, Mohsen

2017-01-01

Cheese and yogurt are two kinds of nutritious dairy products that are used worldwide. The major preservatives in dairy products are sodium benzoate, potassium sorbate, and natamycin. The maximum permitted levels for these additives in cheese and yogurt are established according to Iranian national standards. In this study, we developed a method to detect these preservatives in dairy products by reversed phase chromatography with UV detection in 220 nm, simultaneously. This method was performed on C18 column with ammonium acetate buffer (pH = 5) and acetonitrile (73 : 27 v/v) as mobile phase. The method was carried out on 195 samples in 5 kinds of commercial cheeses and yogurts. The results demonstrated insufficient separation where limit of detection (LOD) and limit of quantitation (LOQ) ranged from 0.326 to 0.520 mg/kg and 0.989 to 1.575 mg/kg in benzoate and sorbate, respectively. The correlation coefficient of each calibration curve was mostly higher than 0.997. All samples contained sodium benzoate in various ranges. Natamycin and sorbate were detected in a remarkable amount of samples, while, according to Iranian national standard, only sorbate is permitted to be added in processed cheeses as a preservative. In order to control the quality of dairy products, determination of preservatives is necessary. PMID:28473855

Innovative qPCR using interfacial effects to enable low threshold cycle detection and inhibition relief

PubMed Central

Harshman, Dustin K.; Rao, Brianna M.; McLain, Jean E.; Watts, George S.; Yoon, Jeong-Yeol

2015-01-01

Molecular diagnostics offers quick access to information but fails to operate at a speed required for clinical decision-making. Our novel methodology, droplet-on-thermocouple silhouette real-time polymerase chain reaction (DOTS qPCR), uses interfacial effects for droplet actuation, inhibition relief, and amplification sensing. DOTS qPCR has sample-to-answer times as short as 3 min 30 s. In infective endocarditis diagnosis, DOTS qPCR demonstrates reproducibility, differentiation of antibiotic susceptibility, subpicogram limit of detection, and thermocycling speeds of up to 28 s/cycle in the presence of tissue contaminants. Langmuir and Gibbs adsorption isotherms are used to describe the decreasing interfacial tension upon amplification. Moreover, a log-linear relationship with low threshold cycles is presented for real-time quantification by imaging the droplet-on-thermocouple silhouette with a smartphone. DOTS qPCR resolves several limitations of commercially available real-time PCR systems, which rely on fluorescence detection, have substantially higher threshold cycles, and require expensive optical components and extensive sample preparation. Due to the advantages of low threshold cycle detection, we anticipate extending this technology to biological research applications such as single cell, single nucleus, and single DNA molecule analyses. Our work is the first demonstrated use of interfacial effects for sensing reaction progress, and it will enable point-of-care molecular diagnosis of infections. PMID:26601245

US EPA's National Dioxin Air Monitoring Network: Analytical ...

EPA Pesticide Factsheets

The U.S. EPA has established a National Dioxin Air Monitoring Network (NDAMN) to determine the temporal and geographical variability of atmospheric chlorinated dibenzo-p-dioxins (CDDs), furans (CDFs), and coplanar polychlorinated biphenyls (PCBs) at rural and non-impacted locations throughout the United States. Currently operating at 32 sampling stations, NDAMN has three primary purposes: (1) to determine the atmospheric levels and occurrences of dioxin-like compounds in rural and agricultural areas where livestock, poultry, and animal feed crops are grown; (2) to provide measurements of atmospheric levels in different geographic regions of the U.S.; and (3) to provide information regarding the long-range transport of dioxin-like compounds in air over the U.S. Designed in 1997, NDAMN has been implemented in phases, with the first phase consisting of 9 monitoring stations and is achieving congener-specific detection lmits of 0.1 fg/m3 for 2,3,7,8-TCDD and 10 fg/m3 for OCDD. With respect to coplanar PCBs, the detection limits are generally higher due to the presence of background levels in the air during the preparation and processing of the samples. Achieving these extremely low levels of detection present a host of analytical issues. Among these issues are the methods used to establish ultra-trace detection limits, measures to ensure against and monitor for breakthrough of native analytes when sampling large volumes of air, and procedures for handling and e

Ternary Surface Monolayers for Ultrasensitive (Zeptomole) Amperometric Detection of Nucleic-Acid Hybridization without Signal Amplification

PubMed Central

Wu, Jie; Campuzano, Susana; Halford, Colin; Haake, David A.; Wang, Joseph

2010-01-01

A ternary surface monolayer, consisting of co-assembled thiolated capture probe (SHCP) mercaptohexanol (MCH) and dithiothreitol (DTT), is shown to offer dramatic improvements in the signal-to-noise characteristics of electrochemical DNA hybridization biosensors based on common self-assembled monolayers (SAMs). Remarkably low detection limits down to 40 zmole (in 4 μL samples) as well as only 1 CFU E. coli per sensor are thus obtained without any additional amplification step in connection to the commonly used horseradish peroxidase/3,3′,5,5′-tetramethylbenzidine (HRP/TMB) system. Such dramatic improvements in the detection limits (compared to common binary alkanethiol interfaces and to most electrochemical DNA sensing strategies without target or signal amplification) are attributed primarily to the remarkably higher resistance to non-specific adsorption. This reflects the highly compact layer (with lower pinhole density) produced by the coupling of the cyclic- and linear-configuration ‘backfillers’ that leads to a remarkably low background noise even in the presence of complex sample matrices. A wide range of surface compositions have been investigated and the ternary mixed monolayer has been systematically optimized. Detailed impedance spectroscopy and cyclic voltammetric studies shed useful insights into the surface coverage. The impressive sensitivity and high specificity of the simple developed methodology indicate great promise for a wide range of nucleic acid testing, including clinical diagnostics, biothreat detection, food safety and forensic analysis. PMID:20883023

Ternary surface monolayers for ultrasensitive (zeptomole) amperometric detection of nucleic acid hybridization without signal amplification.

PubMed

Wu, Jie; Campuzano, Susana; Halford, Colin; Haake, David A; Wang, Joseph

2010-11-01

A ternary surface monolayer, consisting of coassembled thiolated capture probe, mercaptohexanol and dithiothreitol, is shown to offer dramatic improvements in the signal-to-noise characteristics of electrochemical DNA hybridization biosensors based on common self-assembled monolayers. Remarkably low detection limits down to 40 zmol (in 4 μL samples) as well as only 1 CFU Escherichia coli per sensor are thus obtained without any additional amplification step in connection to the commonly used horseradish peroxidase/3,3',5,5'-tetramethylbenzidine system. Such dramatic improvements in the detection limits (compared to those of common binary alkanethiol interfaces and to those of most electrochemical DNA sensing strategies without target or signal amplification) are attributed primarily to the remarkably higher resistance to nonspecific adsorption. This reflects the highly compact layer (with lower pinhole density) produced by the coupling of the cyclic- and linear-configuration "backfillers" that leads to a remarkably low background noise even in the presence of complex sample matrixes. A wide range of surface compositions have been investigated, and the ternary mixed monolayer has been systematically optimized. Detailed impedance spectroscopy and cyclic voltammetric studies shed useful insights into the surface coverage. The impressive sensitivity and high specificity of the simple developed methodology indicate great promise for a wide range of nucleic acid testing, including clinical diagnostics, biothreat detection, food safety, and forensic analysis.

Droplet-Free Digital Enzyme-Linked Immunosorbent Assay Based on a Tyramide Signal Amplification System.

PubMed

Akama, Kenji; Shirai, Kentaro; Suzuki, Seigo

2016-07-19

Digital enzyme-linked immunosorbent assay (ELISA) is a single molecule counting technology and is one of the most sensitive immunoassay methods. The key aspect of this technology is to concentrate enzyme reaction products from a single target molecule in femtoliter droplets. This study presents a novel Digital ELISA that does not require droplets; instead, enzyme reaction products are concentrated using a tyramide signal amplification system. In our method, tyramide substrate reacts with horseradish peroxidase (HRP) labeled with an immunocomplex on beads, and the substrate is converted into short-lived radical intermediates. By adjusting the bead concentration in the HRP-tyramide reaction and conducting the reaction using freely moving beads, tyramide radicals are deposited only on beads labeled with HRP and there is no diffusion to other beads. Consequently, the fluorescence signal is localized on a portion of the beads, making it possible to count the number of labeled beads digitally. The performance of our method was demonstrated by detecting hepatitis B surface antigen with a limit of detection of 0.09 mIU/mL (139 aM) and a dynamic range of over 4 orders of magnitude. The obtained limit of detection represents a >20-fold higher sensitivity than conventional ELISA. Our method has potential applications in simple in vitro diagnostic systems for detecting ultralow concentrations of protein biomarkers.

Supercritical fluid chromatography with photodiode array detection for pesticide analysis in papaya and avocado samples.

PubMed

Pano-Farias, Norma S; Ceballos-Magaña, Silvia G; Gonzalez, Jorge; Jurado, José M; Muñiz-Valencia, Roberto

2015-04-01

To improve the analysis of pesticides in complex food matrices with economic importance, alternative chromatographic techniques, such as supercritical fluid chromatography, can be used. Supercritical fluid chromatography has barely been applied for pesticide analysis in food matrices. In this paper, an analytical method using supercritical fluid chromatography coupled to a photodiode array detection has been established for the first time for the quantification of pesticides in papaya and avocado. The extraction of methyl parathion, atrazine, ametryn, carbofuran, and carbaryl was performed through the quick, easy, cheap, effective, rugged, and safe methodology. The method was validated using papaya and avocado samples. For papaya, the correlation coefficient values were higher than 0.99; limits of detection and quantification ranged from 130-380 and 220-640 μg/kg, respectively; recovery values ranged from 72.8-94.6%; precision was lower than 3%. For avocado, limit of detection values were ˂450 μg/kg; precision was lower than 11%; recoveries ranged from 50.0-94.2%. Method feasibility was tested for lime, banana, mango, and melon samples. Our results demonstrate that the proposed method is applicable to methyl parathion, atrazine, ametryn, and carbaryl, toxics pesticides used worldwide. The methodology presented in this work could be applicable to other fruits. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of Clean-Up Methods for Ochratoxin A on Wine, Beer, Roasted Coffee and Chili Commercialized in Italy

PubMed Central

Prelle, Ambra; Spadaro, Davide; Denca, Aleksandra; Garibaldi, Angelo; Gullino, Maria Lodovica

2013-01-01

The most common technique used to detect ochratoxin A (OTA) in food matrices is based on extraction, clean-up, and chromatography detection. Different clean-up cartridges, such as immunoaffinity columns (IAC), molecular imprinting polymers (MIP), Mycosep™ 229, Mycospin™, and Oasis® HLB (Hydrophilic Lipophilic balance) as solid phase extraction were tested to optimize the purification for red wine, beer, roasted coffee and chili. Recovery, reproducibility, reproducibility, limit of detection (LOD) and limit of quantification (LOQ) were calculated for each clean-up method. IAC demonstrated to be suitable for OTA analysis in wine and beer with recovery rate >90%, as well as Mycosep™ for wine and chili. On the contrary, MIP columns were the most appropriate to clean up coffee. A total of 120 samples (30 wines, 30 beers, 30 roasted coffee, 30 chili) marketed in Italy were analyzed, by applying the developed clean-up methods. Twenty-seven out of 120 samples analyzed (22.7%: two wines, five beers, eight coffees, and 12 chili) resulted positive to OTA. A higher incidence of OTA was found in chili (40.0%) more than wine (6.6%), beers (16.6%) and coffee (26.6%). Moreover, OTA concentration in chili was the highest detected, reaching 47.8 µg/kg. Furthermore, three samples (2.5%), two wines and one chili, exceeded the European threshold. PMID:24152987

Hierarchical Nanogold Labels to Improve the Sensitivity of Lateral Flow Immunoassay

NASA Astrophysics Data System (ADS)

Serebrennikova, Kseniya; Samsonova, Jeanne; Osipov, Alexander

2018-06-01

Lateral flow immunoassay (LFIA) is a widely used express method and offers advantages such as a short analysis time, simplicity of testing and result evaluation. However, an LFIA based on gold nanospheres lacks the desired sensitivity, thereby limiting its wide applications. In this study, spherical nanogold labels along with new types of nanogold labels such as gold nanopopcorns and nanostars were prepared, characterized, and applied for LFIA of model protein antigen procalcitonin. It was found that the label with a structure close to spherical provided more uniform distribution of specific antibodies on its surface, indicative of its suitability for this type of analysis. LFIA using gold nanopopcorns as a label allowed procalcitonin detection over a linear range of 0.5-10 ng mL-1 with the limit of detection of 0.1 ng mL-1, which was fivefold higher than the sensitivity of the assay with gold nanospheres. Another approach to improve the sensitivity of the assay included the silver enhancement method, which was used to compare the amplification of LFIA for procalcitonin detection. The sensitivity of procalcitonin determination by this method was 10 times better the sensitivity of the conventional LFIA with gold nanosphere as a label. The proposed approach of LFIA based on gold nanopopcorns improved the detection sensitivity without additional steps and prevented the increased consumption of specific reagents (antibodies).

[Usefulness of ¹⁸F-fluoro-2-deoxyglucose positron emission tomography in evaluation of gastric cancer stage].

PubMed

Yoon, Na Ri; Park, Jae Myung; Jung, Hee Sun; Cho, Yu Kyung; Lee, In Seok; Choi, Myung Gyu; Chung, In Sik; Song, Kyo Young; Park, Cho Hyun

2012-05-01

The usefulness of ¹⁸F-fluoro-2-deoxyglucose (FDG)-PET in detecting primary cancer, lymph node metastasis, and distant metastasis were studied in the gastric cancer patients. The subjects were 392 gastric cancer patients who received FDG-PET and an abdominal CT test prior to surgery. The results of FDG-PET and CT were compared with the surgical and pathologic results. The primary site detection rate of FDG-PET was 74.4%, 50.3% in early gastric cancer and 92.0% in advanced gastric cancer. Detection rate was higher when tumors were larger than 3.5 cm, had deeper depth of invasion, and at a later stage (p<0.05, respectively). In multivariate analysis, tumor size, spread of tumor cells beyond the muscle layer (≥T2), and lymph node metastasis were statistically significant factors in primary site detection rate. The sensitivity, specificity, and positive predictive value of FDG-PET to lymph node metastasis were 59.6%, 88.8%, and 81.1% respectively, sensitivity being lower compared to CT while specificity and positive predictive value were higher. Sensitivity, specificity, and positive predictive value to distant metastasis were, respectively, 66.7%, 99.2%, and 88.0%, similar to CT. In 21 of the 392 patients (5.4%), synchronous double primary cancers were detected. In gastric cancer, usefullness of FDG-PET is limited to the advanced stage. Diagnostic value of this test was not superior to CT. However, FDG-PET may be useful in detecting synchronous double primary cancers.

Identification and quantification of the main isoflavones and other phytochemicals in soy based nutraceutical products by liquid chromatography-orbitrap high resolution mass spectrometry.

PubMed

López-Gutiérrez, Noelia; Romero-González, Roberto; Garrido Frenich, Antonia; Martínez Vidal, José Luis

2014-06-27

The specific phytochemicals composition of soy nutritional supplements is usually not labelled. Hence, 12 dietary supplements were analyzed in order to detect and identify the main phytochemicals present in these samples, using a database containing 60 compounds. Ultra-high performance liquid chromatography coupled to single-stage Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-MS) has been used. Two consecutive extractions, using as extraction solvent a mixture of methanol:water (80:20, v/v), were employed, followed by two dilutions (10 or 100 times depending on the concentration of the components in the sample) with a mixture of an aqueous solution of ammonium acetate 30mM:methanol (50:50, v/v). The method was validated, obtaining adequate recovery and precision values. Limits of detection (LODs) and quantification (LOQs) were calculated, ranging from 2 to 150μgL(-1). Isoflavones were the predominant components present in the analyzed supplements with values higher than 93% of the total amount of phytochemicals in all cases. The aglycones (genistein, daidzein, glycitein and biochanin A) as well as their three conjugated forms, β-glucosides (genistin, daizin and glycitin) were detected and quantified, being daidzein the isoflavone detected at higher concentration in 8 out of 12 samples reported, with values ranging from 684 to 35,970mgkg(-1), whereas biochanin A was detected at very low concentrations, ranging from 18 to 50mgkg(-1). Moreover, other phytochemicals as flavones, flavonols, flavanones and phenolic acids were also detected and quantified. Copyright © 2014 Elsevier B.V. All rights reserved.

Detection of trace microcystin-LR on a 20 MHz QCM sensor coated with in situ self-assembled MIPs.

PubMed

He, Hao; Zhou, Lianqun; Wang, Yi; Li, Chuanyu; Yao, Jia; Zhang, Wei; Zhang, Qingwen; Li, Mingyu; Li, Haiwen; Dong, Wen-fei

2015-01-01

A 20 MHz quartz crystal microbalance (QCM) sensor coated with in situ self-assembled molecularly imprinted polymers (MIPs) was presented for the detection of trace microcystin-LR (MC-LR) in drinking water. The sensor performance obtained using the in situ self-assembled MIPs was compared with traditionally synthesized MIPs on 20 MHz and normal 10 MHz QCM chip. The results show that the response increases by more than 60% when using the in situ self-assembly method compared using the traditionally method while the 20 MHz QCM chip provides four-fold higher response than the 10 MHz one. Therefore, the in situ self-assembled MIPs coated on a high frequency QCM chip was used in the sensor performance test to detect MC-LR in tap water. It showed a limit of detection (LOD) of 0.04 nM which is lower than the safety guideline level (1 nM MC-LR) of drinking water in China. The low sensor response to other analogs indicated the high specificity of the sensor to MC-LR. The sensor showed high stability and low signal variation less than 2.58% after regeneration. The lake water sample analysis shows the sensor is possible for practical use. The combination of the higher frequency QCM with the in situ self-assembled MIPs provides a good candidate for the detection of other small molecules. Copyright © 2014 Elsevier B.V. All rights reserved.

A homogeneous, Anti-dsDNA antibody-based assay for multicolor detection of cancer stem cell transcription factors.

PubMed

Ma, Jiehua; Shi, Hai; Zhang, Meiling; Li, Chao; Xiang, Yang; Liu, Ping

2018-10-31

Cancer stem cells (CSCs) are responsible for maintaining tumor growth, metastasis and recurrence. The high expression of cancer stem cell transcription factors (Oct4, Sox2 and Nanog) is a valuable prognostic factor, suggesting a higher risk of tumor recurrence and metastasis. So, the development of a convenient and cost-effective method for multiplex assay of these transcription factors (TFs) is highly required. In this work, we have proposed a universal homogeneous assay for multicolor detection of these TFs based on anti-dsDNA antibody-decorated Fe 3 O 4 magnetite nanoparticles (aadMNPs). In the presence of analytes, the dye-labeled dsDNAs are bound by specific TFs, which will inhibit the interactions between the dsDNAs and aadMNPs, generating higher fluorescence that may provide signal readout for the immunosensing process. By using the proposed method, Oct4 can be determined in a linear range from 3 to 1200 ng/mL with a detection limit of 0.035 ng/mL. Furthermore, we have presented assays for the sensitive, selective and rapid detection of Oct4, Sox2 and Nanog in cell extract, as well as the analysis of binding affinity of the mutated binding sequences. This work may provide potential applications in clinical CSCs detections, and may open new opportunity for the study of nucleotide polymorphisms in TF binding sites. Copyright © 2018 Elsevier B.V. All rights reserved.

An efficient ratiometric fluorescence sensor based on metal-organic frameworks and quantum dots for highly selective detection of 6-mercaptopurine.

PubMed

Jin, Meng; Mou, Zhao-Li; Zhang, Rui-Ling; Liang, Si-Si; Zhang, Zhi-Qi

2017-05-15

The development of a simple and accurate quantitative method for the determination of 6-mercaptopurine (6-MP) is of great importance because of its serious side effects. Ratiometric fluorescence (RF) sensors are not subject to interference from environmental factors, and exhibit enhanced precision and accuracy. Therefore, a novel RF sensor for the selective detection of 6-MP was developed based on a dual-emission nanosensor. The nanosensor was fabricated by combining a blue-emission metal-organic framework (MOF) NH 2 -MIL-53(Al) (λ em =425nm) with green-emission 3-mercaptopropionic acid-capped CdTe quantum dots (MPA-CdTe QDs) (λ em =528nm) under a single excitation wavelength (335nm). Upon addition of 6-MP, the fluorescence of NH 2 -MIL-53(Al) in the nanohybrid was selectively quenched due to strong inner filter effects, while the fluorescence of the MPA-CdTe QDs was enhanced. The novel RF sensor exhibited higher selectivity towards 6-MP than CdTe QDs alone, and higher sensitivity than MOFs alone. 6-MP could be detected in the range of 0-50μM with a detection limit of 0.15μM (S/N=3). The developed sensor was applied for the determination of 6-MP in human urine samples and satisfactory results were obtained. Overall, a novel and efficient fluorescence-based method was developed for the detection of 6-MP in biosamples. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrasensitive colorimetric immunoassay for hCG detection based on dual catalysis of Au@Pt core-shell nanoparticle functionalized by horseradish peroxidase

NASA Astrophysics Data System (ADS)

Wang, Weiguo; Zou, Yake; Yan, Jinwu; Liu, Jing; Chen, Huixiong; Li, Shan; Zhang, Lei

2018-03-01

In this paper, an ultrasensitive colorimetric biosensor for human chorionic gonadotrophin (hCG) detection was designed from bottom-up method based on the dual catalysis of the horseradish peroxidase (HRP) and Au@Pt nanoparticles (NPs) relative to H2O2-TEM system. HRP and monoclonal mouse anti-hCG antibody (β-submit, mAb1) were co-immobilized onto the Au@Pt NP surface to improve catalytic efficiency and specificity, which formed a dual functionalized Au@Pt-HRP probe with the mean size of 42.8 nm (D50). The colorimetric immunoassay was developed for the hCG detection, and the Au@Pt-HRP probe featured a higher sensitivity in the concentration range of 0.4-12.8 IU L- 1 with a low limit of detection (LOD) of 0.1 IU L- 1 compared with the LODs of 0.8 IU L- 1 for BA-ELISA and of 2.0 IU L- 1 for Au@Pt, which indicated that the Au@Pt-HRP probe possessed higher catalytic efficiency with 2.8-fold increase over Au@Pt and 33.8-fold increase over HRP. Also, the Au@Pt-HRP probe exhibited good precision and reproducibility, high specificity and acceptable accuracy with CV being less than 15%. The dual functionalized Au@Pt-HRP probe as a type of signal amplified method was firstly applied in the colorimetric immunoassay for the hCG detection.

Influence of respiratory tract disease and mode of inhalation on detectability of budesonide in equine urine and plasma.

PubMed

Barton, Ann Kristin; Heinemann, Henrike; Schenk, Ina; Machnik, Marc; Gehlen, Heidrun

2017-02-01

OBJECTIVE To evaluate the influence of respiratory tract disease (ie, recurrent airway obstruction [RAO]) and mode of inhalation on detectability of inhaled budesonide in equine plasma and urine samples. ANIMALS 16 horses (8 healthy control horses and 8 horses affected by RAO, as determined by results of clinical examination, blood gas analysis, bronchoscopy, and cytologic examination of bronchoalveolar lavage fluid). PROCEDURES 4 horses of each group inhaled budesonide (3 μg/kg) twice daily for 10 days while at rest, and the remaining 4 horses of each group inhaled budesonide during lunging exercise. Plasma and urine samples were obtained 4 to 96 hours after inhalation and evaluated for budesonide and, in urine samples, the metabolites 6β-hydroxybudesonide and 16α-hydroxyprednisolone. RESULTS Detected concentrations of budesonide were significantly higher at all time points for RAO-affected horses, compared with concentrations for the control horses. All samples of RAO-affected horses contained budesonide concentrations above the limit of detection at 96 hours after inhalation, whereas this was found for only 2 control horses. Detected concentrations of budesonide were higher, but not significantly so, at all time points in horses that inhaled budesonide during exercise, compared with concentrations for inhalation at rest. CONCLUSIONS AND CLINICAL RELEVANCE Results of this study indicated that the time interval between inhalation of a glucocorticoid and participation in sporting events should be increased when inhalation treatment is administered during exercise to horses affected by respiratory tract disease.

Biotin-Streptavidin Competition Mediates Sensitive Detection of Biomolecules in Enzyme Linked Immunosorbent Assay.

PubMed

Lakshmipriya, Thangavel; Gopinath, Subash C B; Tang, Thean-Hock

2016-01-01

Enzyme Linked Immunosorbent Assay (ELISA) is the gold standard assay for detecting and identifying biomolecules using antibodies as the probe. Improving ELISA is crucial for detecting disease-causing agents and facilitating diagnosis at the early stages of disease. Biotinylated antibody and streptavidin-conjugated horse radish peroxide (streptavidin-HRP) often are used with ELISA to enhance the detection of various kinds of targets. In the present study, we used a competition-based strategy in which we pre-mixed free biotin with streptavidin-HRP to generate high-performance system, as free biotin occupies some of the biotin binding sites on streptavidin, thereby providing more chances for streptavidin-HRP to bind with biotinylated antibody. ESAT-6, which is a protein secreted early during tuberculosis infection, was used as the model target. We found that 8 fM of free biotin mixed with streptavidin-HRP anchored the higher detection level of ESAT-6 by four-fold compared with detection without free biotin (only streptavidin-HRP), and the limit of detection of the new method was 250 pM. These results suggest that biotin-streptavidin competition can be used to improve the diagnosis of analytes in other types of sensors.

Biotin-Streptavidin Competition Mediates Sensitive Detection of Biomolecules in Enzyme Linked Immunosorbent Assay

PubMed Central

Lakshmipriya, Thangavel; Gopinath, Subash C. B.; Tang, Thean-Hock

2016-01-01

Enzyme Linked Immunosorbent Assay (ELISA) is the gold standard assay for detecting and identifying biomolecules using antibodies as the probe. Improving ELISA is crucial for detecting disease-causing agents and facilitating diagnosis at the early stages of disease. Biotinylated antibody and streptavidin-conjugated horse radish peroxide (streptavidin-HRP) often are used with ELISA to enhance the detection of various kinds of targets. In the present study, we used a competition-based strategy in which we pre-mixed free biotin with streptavidin-HRP to generate high-performance system, as free biotin occupies some of the biotin binding sites on streptavidin, thereby providing more chances for streptavidin-HRP to bind with biotinylated antibody. ESAT-6, which is a protein secreted early during tuberculosis infection, was used as the model target. We found that 8 fM of free biotin mixed with streptavidin-HRP anchored the higher detection level of ESAT-6 by four-fold compared with detection without free biotin (only streptavidin-HRP), and the limit of detection of the new method was 250 pM. These results suggest that biotin-streptavidin competition can be used to improve the diagnosis of analytes in other types of sensors. PMID:26954237

Analysis of monoglycerides, diglycerides, sterols, and free fatty acids in coconut (Cocos nucifera L.) oil by 31P NMR spectroscopy.

PubMed

Dayrit, Fabian M; Buenafe, Olivia Erin M; Chainani, Edward T; de Vera, Ian Mitchelle S

2008-07-23

Phosphorus-31 nuclear magnetic resonance spectroscopy ( (31)P NMR) was used to differentiate virgin coconut oil (VCO) from refined, bleached, deodorized coconut oil (RCO). Monoglycerides (MGs), diglycerides (DGs), sterols, and free fatty acids (FFAs) in VCO and RCO were converted into dioxaphospholane derivatives and analyzed by (31)P NMR. On the average, 1-MG was found to be higher in VCO (0.027%) than RCO (0.019%). 2-MG was not detected in any of the samples down to a detection limit of 0.014%. On the average, total DGs were lower in VCO (1.55%) than RCO (4.10%). When plotted in terms of the ratio [1,2-DG/total DGs] versus total DGs, VCO and RCO samples grouped separately. Total sterols were higher in VCO (0.096%) compared with RCO (0.032%), and the FFA content was 8 times higher in VCO than RCO (0.127% vs 0.015%). FFA determination by (31)P NMR and titration gave comparable results. Principal components analysis shows that the 1,2-DG, 1,3-DG, and FFAs are the most important parameters for differentiating VCO from RCO.

Performance evaluation and modeling of a conformal filter (CF) based real-time standoff hazardous material detection sensor

NASA Astrophysics Data System (ADS)

Nelson, Matthew P.; Tazik, Shawna K.; Bangalore, Arjun S.; Treado, Patrick J.; Klem, Ethan; Temple, Dorota

2017-05-01

Hyperspectral imaging (HSI) systems can provide detection and identification of a variety of targets in the presence of complex backgrounds. However, current generation sensors are typically large, costly to field, do not usually operate in real time and have limited sensitivity and specificity. Despite these shortcomings, HSI-based intelligence has proven to be a valuable tool, thus resulting in increased demand for this type of technology. By moving the next generation of HSI technology into a more adaptive configuration, and a smaller and more cost effective form factor, HSI technologies can help maintain a competitive advantage for the U.S. armed forces as well as local, state and federal law enforcement agencies. Operating near the physical limits of HSI system capability is often necessary and very challenging, but is often enabled by rigorous modeling of detection performance. Specific performance envelopes we consistently strive to improve include: operating under low signal to background conditions; at higher and higher frame rates; and under less than ideal motion control scenarios. An adaptable, low cost, low footprint, standoff sensor architecture we have been maturing includes the use of conformal liquid crystal tunable filters (LCTFs). These Conformal Filters (CFs) are electro-optically tunable, multivariate HSI spectrometers that, when combined with Dual Polarization (DP) optics, produce optimized spectral passbands on demand, which can readily be reconfigured, to discriminate targets from complex backgrounds in real-time. With DARPA support, ChemImage Sensor Systems (CISS™) in collaboration with Research Triangle Institute (RTI) International are developing a novel, real-time, adaptable, compressive sensing short-wave infrared (SWIR) hyperspectral imaging technology called the Reconfigurable Conformal Imaging Sensor (RCIS) based on DP-CF technology. RCIS will address many shortcomings of current generation systems and offer improvements in operational agility and detection performance, while addressing sensor weight, form factor and cost needs. This paper discusses recent test and performance modeling results of a RCIS breadboard apparatus.

Super-Eddington Mechanical Power of an Accreting Black Hole in M83

NASA Technical Reports Server (NTRS)

Soria, R.; Long, K. S.; Blair, W. P.; Godfrey, L.; Kuntz, K. D.; Lenc, E.; Stockdale, C.; Winkler, P. F.

2014-01-01

Mass accretion onto black holes releases energy in the form of radiation and outflows. Although the radiative flux cannot substantially exceed the Eddington limit, at which the outgoing radiation pressure impedes the inflow of matter, it remains unclear whether the kinetic energy flux is bounded by this same limit. Here, we present the detection of a radio-optical structure, powered by outflows from a non-nuclear black hole. Its accretion disk properties indicate that this black hole is less than 100 solar masses. The optical-infrared line emission implies an average kinetic power of 3 × 10(exp 40) erg second(exp -1), higher than the Eddington luminosity of the black hole. These results demonstrate kinetic power exceeding the Eddington limit over a sustained period, which implies greater ability to influence the evolution of the black hole's environment.

Super-Eddington mechanical power of an accreting black hole in M83.

PubMed

Soria, R; Long, K S; Blair, W P; Godfrey, L; Kuntz, K D; Lenc, E; Stockdale, C; Winkler, P F

2014-03-21

Mass accretion onto black holes releases energy in the form of radiation and outflows. Although the radiative flux cannot substantially exceed the Eddington limit, at which the outgoing radiation pressure impedes the inflow of matter, it remains unclear whether the kinetic energy flux is bounded by this same limit. Here, we present the detection of a radio-optical structure, powered by outflows from a non-nuclear black hole. Its accretion disk properties indicate that this black hole is less than 100 solar masses. The optical-infrared line emission implies an average kinetic power of 3 × 10(40) erg second(-1), higher than the Eddington luminosity of the black hole. These results demonstrate kinetic power exceeding the Eddington limit over a sustained period, which implies greater ability to influence the evolution of the black hole's environment.

Search for Neutrinos in Super-Kamiokande Associated with the GW170817 Neutron-star Merger

NASA Astrophysics Data System (ADS)

Abe, K.; Bronner, C.; Hayato, Y.; Ikeda, M.; Iyogi, K.; Kameda, J.; Kato, Y.; Kishimoto, Y.; Marti, Ll.; Miura, M.; Moriyama, S.; Nakahata, M.; Nakajima, Y.; Nakano, Y.; Nakayama, S.; Orii, A.; Pronost, G.; Sekiya, H.; Shiozawa, M.; Sonoda, Y.; Takeda, A.; Takenaka, A.; Tanaka, H.; Tasaka, S.; Yano, T.; Akutsu, R.; Kajita, T.; Nishimura, Y.; Okumura, K.; Tsui, K. M.; Labarga, L.; Fernandez, P.; Blaszczyk, F. d. M.; Kachulis, C.; Kearns, E.; Raaf, J. L.; Stone, J. L.; Sulak, L. R.; Berkman, S.; Tobayama, S.; Bian, J.; Elnimr, M.; Kropp, W. R.; Locke, S.; Mine, S.; Weatherly, P.; Smy, M. B.; Sobel, H. W.; Takhistov, V.; Ganezer, K. S.; Hill, J.; Kim, J. Y.; Lim, I. T.; Park, R. G.; Li, Z.; O’Sullivan, E.; Scholberg, K.; Walter, C. W.; Gonin, M.; Imber, J.; Mueller, Th. A.; Ishizuka, T.; Nakamura, T.; Jang, J. S.; Choi, K.; Learned, J. G.; Matsuno, S.; Amey, J.; Litchfield, R. P.; Ma, W. Y.; Uchida, Y.; Wascko, M. O.; Catanesi, M. G.; Intonti, R. A.; Radicioni, E.; De Rosa, G.; Ali, A.; Collazuol, G.; Ludovici, L.; Cao, S.; Friend, M.; Hasegawa, T.; Ishida, T.; Ishii, T.; Kobayashi, T.; Nakadaira, T.; Nakamura, K.; Oyama, Y.; Sakashita, K.; Sekiguchi, T.; Tsukamoto, T.; Abe, KE.; Hasegawa, M.; Suzuki, A. T.; Takeuchi, Y.; Hayashino, T.; Hirota, S.; Jiang, M.; Mori, M.; Nakamura, KE.; Nakaya, T.; Wendell, R. A.; Anthony, L. H. V.; McCauley, N.; Pritchard, A.; Fukuda, Y.; Itow, Y.; Murase, M.; Muto, F.; Mijakowski, P.; Frankiewicz, K.; Jung, C. K.; Li, X.; Palomino, J. L.; Santucci, G.; Viela, C.; Wilking, M. J.; Yanagisawa, C.; Fukuda, D.; Ishino, H.; Ito, S.; Kibayashi, A.; Koshio, Y.; Nagata, H.; Sakuda, M.; Xu, C.; Kuno, Y.; Wark, D.; Di Lodovico, F.; Richards, B.; Molina Sedgwick, S.; Tacik, R.; Kim, S. B.; Cole, A.; Thompson, L.; Okazawa, H.; Choi, Y.; Ito, K.; Nishijima, K.; Koshiba, M.; Suda, Y.; Yokoyama, M.; Calland, R. G.; Hartz, M.; Martens, K.; Murdoch, M.; Quilain, B.; Simpson, C.; Suzuki, Y.; Vagins, M. R.; Hamabe, D.; Kuze, M.; Okajima, Y.; Yoshida, T.; Ishitsuka, M.; Martin, J. F.; Nantais, C. M.; Tanaka, H. A.; Towstego, T.; Konaka, A.; Chen, S.; Wan, L.; Minamino, A.; The Super-Kamiokande Collaboration

2018-04-01

We report the results of a neutrino search in Super-Kamiokande (SK) for coincident signals with the first detected gravitational wave (GW) produced by a binary neutron-star merger, GW170817, which was followed by a short gamma-ray burst, GRB170817A, and a kilonova/macronova. We searched for coincident neutrino events in the range from 3.5 MeV to ∼100 PeV, in a time window ±500 s around the gravitational wave detection time, as well as during a 14-day period after the detection. No significant neutrino signal was observed for either time window. We calculated 90% confidence level upper limits on the neutrino fluence for GW170817. From the upward-going-muon events in the energy region above 1.6 GeV, the neutrino fluence limit is {16.0}-0.6+0.7 ({21.3}-0.8+1.1) cm‑2 for muon neutrinos (muon antineutrinos), with an error range of ±5° around the zenith angle of NGC4993, and the energy spectrum is under the assumption of an index of ‑2. The fluence limit for neutrino energies less than 100 MeV, for which the emission mechanism would be different than for higher-energy neutrinos, is also calculated. It is 6.6 × 107 cm‑2 for anti-electron neutrinos under the assumption of a Fermi–Dirac spectrum with average energy of 20 MeV.

A New Method for the Fast Analysis of Trihalomethanes in Tap and Recycled Waters Using Headspace Gas Chromatography with Micro-Electron Capture Detection

PubMed Central

Alexandrou, Lydon D.; Meehan, Barry J.; Morrison, Paul D.; Jones, Oliver A. H.

2017-01-01

Chemical disinfection of water supplies brings significant public health benefits by reducing microbial contamination. The process can however, result in the formation of toxic compounds through interactions between disinfectants and organic material in the source water. These new compounds are termed disinfection by-products (DBPs). The most common are the trihalomethanes (THMs) such as trichloromethane (chloroform), dichlorobromomethane, chlorodibromomethane and tribromomethane (bromoform); these are commonly reported as a single value for total trihalomethanes (TTHMs). Analysis of DBPs is commonly performed via time- and solvent-intensive sample preparation techniques such as liquid–liquid and solid phase extraction. In this study, a method using headspace gas chromatography with micro-electron capture detection was developed and applied for the analysis of THMs in drinking and recycled waters from across Melbourne (Victoria, Australia). The method allowed almost complete removal of the sample preparation step whilst maintaining trace level detection limits (>1 ppb). All drinking water samples had TTHM concentrations below the Australian regulatory limit of 250 µg/L but some were above the U.S. EPA limit of 60 µg/L. The highest TTHM concentration was 67.2 µg/L and lowest 22.9 µg/L. For recycled water, samples taken directly from treatment plants held significantly higher concentrations (153.2 µg/L TTHM) compared to samples from final use locations (4.9–9.3 µg/L). PMID:28505068

Analysis of carbonaceous biomarkers with the Mars Organic Analyzer microchip capillary electrophoresis system: carboxylic acids.

PubMed

Stockton, Amanda M; Tjin, Caroline Chandra; Chiesl, Thomas N; Mathies, Richard A

2011-01-01

The oxidizing surface chemistry on Mars argues that any comprehensive search for organic compounds indicative of life requires methods to analyze higher oxidation states of carbon with very low limits of detection. To address this goal, microchip capillary electrophoresis (μCE) methods were developed for analysis of carboxylic acids with the Mars Organic Analyzer (MOA). Fluorescent derivatization was achieved by activation with the water soluble 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) followed by reaction with Cascade Blue hydrazide in 30 mM borate, pH 3. A standard containing 12 carboxylic acids found in terrestrial life was successfully labeled and separated in 30 mM borate at pH 9.5, 20 °C by using the MOA CE system. Limits of detection were 5-10 nM for aliphatic monoacids, 20 nM for malic acid (diacid), and 230 nM for citric acid (triacid). Polyacid benzene derivatives containing 2, 3, 4, and 6 carboxyl groups were also analyzed. In particular, mellitic acid was successfully labeled and analyzed with a limit of detection of 300 nM (5 ppb). Analyses of carboxylic acids sampled from a lava tube cave and a hydrothermal area demonstrated the versatility and robustness of our method. This work establishes that the MOA can be used for sensitive analyses of a wide range of carboxylic acids in the search for extraterrestrial organic molecules. © Mary Ann Liebert, Inc.

Amperometric L-lysine enzyme electrodes based on carbon nanotube/redox polymer and graphene/carbon nanotube/redox polymer composites.

PubMed

Kaçar, Ceren; Erden, Pınar Esra; Kılıç, Esma

2017-04-01

Highly sensitive L-lysine enzyme electrodes were constructed by using poly(vinylferrocene)-multiwalled carbon nanotubes-gelatine (PVF/MWCNTs-GEL) and poly(vinylferrocene)-multiwalled carbon nanotubes-gelatine-graphene (PVF/MWCNTs-GEL/GR) composites as sensing interfaces and their performances were evaluated. Lysine oxidase (LO) was immobilized onto the composite modified glassy carbon electrodes (GCE) by crosslinking using glutaraldehyde and bovine serum albumin. Effects of pH value, enzyme loading, applied potential, electrode composition, and interfering substances on the amperometric response of the enzyme electrodes were discussed. The analytical characteristics of the enzyme electrodes were also investigated. The linear range, detection limit, and sensitivity of the LO/PVF/MWCNTs-GEL/GCE were 9.9 × 10 -7 -7.0 × 10 -4  M, 1.8 × 10 -7  M (S/N = 3), and 13.51 μA mM -1  cm -2 , respectively. PVF/MWCNTs-GEL/GR-based L-lysine enzyme electrode showed a short response time (<5 s) and a linear detection range from 9.9 × 10 -7 to 7.0 × 10 -4  M with good sensitivity of 17.8 μA mM -1  cm -2 and a low detection limit of 9.2 × 10 -8  M. The PVF/MWCNTs-GEL/GR composite-based L-lysine enzyme electrode exhibited about 1.3-fold higher sensitivity than its MWCNTs-based counterpart and its detection limit was superior to the MWCNTs-based one. In addition, enzyme electrodes were successfully applied to determine L-lysine in pharmaceutical sample and cheese.

Clinical relevance of the modified physical performance test versus the short physical performance battery for detecting mobility impairments in older men with peripheral arterial disease.

PubMed

Addison, Odessa; Kundi, Rishi; Ryan, Alice S; Goldberg, Andrew P; Patel, Richa; Lal, Brajesh K; Prior, Steven J

2017-08-23

The study is to compare the Modified Physical Performance Test (MPPT) and Short Physical Performance Battery (SPPB) as metrics of mobility and function in older men with peripheral arterial disease (PAD). A total of 51 men (55-87 years) with PAD underwent functional testing including the SPPB, MPPT, Walking Impairment Questionnaire (WIQ), stair ascent, and 6-min walk distance. Individuals were grouped according to SPPB and MPPT scores as not limited on either, limited only on the MPPT, or limited on both. The MPPT identified a higher proportion of patients as being functionally limited than the SPPB (p < 0.001). Men identified as limited only by the MPPT, and not the SPPB, were subsequently confirmed to have lower function on all measures compared to those not identified as limited by either the SPPB or the MPPT (p < 0.02). These findings suggest the MPPT is an appropriate measure to identify early declines in men with PAD and may identify global disability better than SPPB. Implications for rehabilitation Individuals with peripheral arterial disease have low activity levels and are at risk for a loss of independence and global disability. Early detection of decline in mobility and global function would allow for interventions before large changes in ambulatory ability or a loss of functional independence occur. This study shows the Modified Physical Performance Test may be an appropriate test to identify early decline in function in men with peripheral arterial disease.

[Detecting fire smoke based on the multispectral image].

PubMed

Wei, Ying-Zhuo; Zhang, Shao-Wu; Liu, Yan-Wei

2010-04-01

Smoke detection is very important for preventing forest-fire in the fire early process. Because the traditional technologies based on video and image processing are easily affected by the background dynamic information, three limitations exist in these technologies, i. e. lower anti-interference ability, higher false detection rate and the fire smoke and water fog being not easily distinguished. A novel detection method for detecting smoke based on the multispectral image was proposed in the present paper. Using the multispectral digital imaging technique, the multispectral image series of fire smoke and water fog were obtained in the band scope of 400 to 720 nm, and the images were divided into bins. The Euclidian distance among the bins was taken as a measurement for showing the difference of spectrogram. After obtaining the spectral feature vectors of dynamic region, the regions of fire smoke and water fog were extracted according to the spectrogram feature difference between target and background. The indoor and outdoor experiments show that the smoke detection method based on multispectral image can be applied to the smoke detection, which can effectively distinguish the fire smoke and water fog. Combined with video image processing method, the multispectral image detection method can also be applied to the forest fire surveillance, reducing the false alarm rate in forest fire detection.

Psychopharmacology of theobromine in healthy volunteers.

PubMed

Baggott, Matthew J; Childs, Emma; Hart, Amy B; de Bruin, Eveline; Palmer, Abraham A; Wilkinson, Joy E; de Wit, Harriet

2013-07-01

Theobromine, a methylxanthine related to caffeine and present in high levels in cocoa, may contribute to the appeal of chocolate. However, current evidence for this is limited. We conducted a within-subjects placebo-controlled study of a wide range of oral theobromine doses (250, 500, and 1,000 mg) using an active control dose of caffeine (200 mg) in 80 healthy participants. Caffeine had the expected effects on mood including feelings of alertness and cardiovascular parameters. Theobromine responses differed according to dose; it showed limited subjective effects at 250 mg and negative mood effects at higher doses. It also dose-dependently increased heart rate. In secondary analyses, we also examined individual differences in the drug's effects in relation to genes related to their target receptors, but few associations were detected. This study represents the highest dose of theobromine studied in humans. We conclude that theobromine at normal intake ranges may contribute to the positive effects of chocolate, but at higher intakes, effects become negative.

Psychopharmacology of theobromine in healthy volunteers

PubMed Central

Baggott, Matthew J.; Childs, Emma; Hart, Amy B.; de Bruin, Eveline; Palmer, Abraham A.; Wilkinson, Joy E.; de Wit, Harriet

2013-01-01

Background Theobromine, a methylxanthine related to caffeine and present in high levels in cocoa, may contribute to the appeal of chocolate. However, currently evidence for this is limited. Objectives We conducted a within-subjects placebo-controlled study of a wide range of oral theobromine doses (250, 500, and 1000 mg) using an active control dose of caffeine (200 mg) in 80 healthy participants. Results Caffeine had the expected effects on mood including feelings of alertness, and cardiovascular parameters. Theobromine responses differed according to dose: it showed limited subjective effects at 250 mg and negative mood effects at higher doses. It also dose-dependently increased heart rate. In secondary analyses we also examined individual differences in the drugs' effects in relation to genes related to their target receptors, but few associations were detected. Conclusions This study represents the highest dose of theobromine studied in humans. We conclude that theobromine at normal intake ranges may contribute to the positive effects of chocolate, but at higher intakes effects become negative. PMID:23420115

Microsite and elevation zone effects on seed pilferage, germination, and seedling survival during early whitebark pine recruitment.

PubMed

Pansing, Elizabeth R; Tomback, Diana F; Wunder, Michael B; French, Joshua P; Wagner, Aaron C

2017-11-01

Tree recruitment is a spatially structured process that may undergo change over time because of variation in postdispersal processes. We examined seed pilferage, seed germination, and seedling survival in whitebark pine to determine whether 1) microsite type alters the initial spatial pattern of seed caches, 2) higher abiotic stress (i.e. higher elevations) exacerbates spatial distribution changes, and 3) these postdispersal processes are spatially clustered. At two study areas, we created a seed distribution pattern by burying seed caches in microsite types frequently used by whitebark pine's avian seed disperser (Clark's nutcracker) in upper subalpine forest and at treeline, the latter characterized by high abiotic environmental stress. We monitored caches for two years for pilferage, germination, and seedling survival. Odds of pilferage (both study areas), germination (northern study area), and survival (southern study area) were higher at treeline relative to subalpine forest. At the southern study area, we found higher odds of 1) pilferage near rocks and trees relative to no object in subalpine forest, 2) germination near rocks relative to trees within both elevation zones, and 3) seedling survival near rocks and trees relative to no object at treeline. No microsite effects were detected at the northern study area. Findings indicated that the microsite distribution of seed caches changes with seed/seedling stage. Higher odds of seedling survival near rocks and trees were observed at treeline, suggesting abiotic stress may limit safe site availability, thereby shifting the spatial distribution toward protective microsites. Higher odds of pilferage at treeline, however, suggest rodents may limit treeline recruitment. Further, odds of pilferage were higher near rocks and trees relative to no object in subalpine forest but did not differ among microsites at treeline, suggesting pilferage can modulate the spatial structure of regeneration, a finding supported by limited clustering of postdispersal processes.

Development of a novel solid-phase extraction element for the detection of nonylphenol in the surface water of Hangzhou.

PubMed

Lou, Liping; Cheng, Guanghuan; Yang, Qiang; Xu, Xinhua; Hu, Baolan; Chen, Yingxu

2012-02-01

Nonylphenol (NP) is a representative environmental endocrine-disrupting chemical and persistent toxic pollutant. Previous studies have shown that the average concentration of NP in environmental waters was approximately tens to hundreds of ng L(-1) and it could even reach up to tens of μg L(-1). A simple, fast and accurate method employing a novel solid-phase extraction element named "Magic Chemisorber" (MC) followed by high-performance liquid chromatography (HPLC) using a fluorescence detector (FLD) was used for detecting NP. The most important parameters that affect the extraction process, including extraction time, desorption time, desorption solvent and repeatability, were optimized. The MC-HPLC method showed good linearity with concentrations of NP from 10 to 200 μg L(-1), a correlation coefficient of 0.9995 and the limit of detection (LOD) and limit of quantification (LOQ) of this method was 0.44 and 1.47 μg L(-1), respectively. Compared to commercial polydimethylsiloxane (PDMS) glass fiber, MC had both higher capacity and recovery and it could be used repeatedly. Using the MC-HPLC method we found that the concentration of NP in river water from Hangzhou city ranged from 8.54 ± 1.23 μg L(-1) (Qiantang River) to 65.77 ± 3.69 μg L(-1) (Tiesha River), which was similar to that of international regions heavily polluted with NP and higher than that of Bohai Bay, the Yellow River and the Pearl River Delta in China. This level of NP pollution is possibly related to the rapid development of the textile, printing and paper industries of Zhejiang province.

Deep L'- and M-band Imaging for Planets around Vega and epsilon Eridani

NASA Astrophysics Data System (ADS)

Heinze, A. N.; Hinz, Philip M.; Kenworthy, Matthew; Miller, Douglas; Sivanandam, Suresh

2008-11-01

We have obtained deep adaptive optics (AO) images of Vega and epsilon Eri to search for planetary mass companions. We observed at the MMT in the L' (3.8 μm) and M (4.8 μm) bands using Clio, a recently commissioned imager optimized for these wavelengths. Observing at these long wavelengths represents a departure from the H band (1.65 μm) more commonly used for AO imaging searches for extrasolar planets. The long wavelengths offer better predicted planet/star flux ratios and cleaner (higher Strehl) AO images at the cost of lower diffraction-limited resolution and higher sky background. We have not detected any planets or planet candidates around Vega or epsilon Eri. We report the sensitivities obtained around both stars, which correspond to upper limits on any planetary companions which may exist. The sensitivities of our L'- and M-band observations are comparable to those of the best H-regime observations of these stars. For epsilon Eri, our M-band observations deliver considerably better sensitivity to close-in planets than any previously published results, and we show that the M band is by far the best wavelength choice for attempts at ground-based AO imaging of the known planet epsilon Eri b. The Clio camera itself, with MMTAO, may be capable of detecting epsilon Eri b at its 2010 apastron, given a multinight observing campaign. Clio appears to be the only currently existing AO imager that has a realistic possibility of detecting epsilon Eri b. Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.

Improved detection sensitivity of γ-aminobutyric acid based on graphene oxide interface on an optical microfiber.

PubMed

Zhou, Jun; Huang, Yunyun; Chen, Chaoyan; Xiao, Aoxiang; Guo, Tuan; Guan, Bai-Ou

2018-05-11

Interfacing bio-recognition elements to optical materials is a longstanding challenge to manufacture sensitive biosensors and inexpensive diagnostic devices. In this work, a graphene oxide (GO) interface has been constructed between silica microfiber and bio-recognition elements to develop an improved γ-aminobutyric acid (GABA) sensing approach. The GO interface, which was located at the site with the strongest evanescent field on the microfiber surface, improved the detection sensitivity by providing a larger platform for more bio-recognition element immobilization, and amplifying surface refractive index change caused by combination between bio-recognition elements and target molecules. Owing to the interface improvement, the microfiber has a three times improved sensitivity of 1.03 nm/log M for GABA detection, and hence a lowest limit of detection of 2.91 × 10-18 M, which is 7 orders of magnitude higher than that without the GO interface. Moreover, the micrometer-sized footprint and non-radioactive nature enable easy implantation in human brains for in vivo applications.

An Amperometric Acetylcholinesterase Sensor Based on the Bio-templated Synthesis of Hierarchical Mesoporous Bioactive Glass Microspheres

NASA Astrophysics Data System (ADS)

Lv, Zhuo; Luo, Ruiping; Xi, Lijuan; Chen, Yang; Wang, Hongsu

2017-11-01

This work describes the synthesis of three-dimensional hollow hierarchical mesoporous bioactive glass (HMBG) microspheres based on Herba leonuri pollen grains via a hydrothermal method. The HMBG microspheres perfectly copied the hierarchical porous structure and inner hollow structure constituting the double-layer surface of the natural Herba leonuri pollen grains. This structural mimicry of the pollen grains resulted in a higher degree of adsorption of acetylcholinesterase (AChE) on HMBG microspheres in comparison with mesoporous bioactive glass. Subsequently, an amperometric biosensor for the detection of Malathion was fabricated by immobilizing AChE onto an HMBG microspheres-modified carbon paste electrode. The biosensor response exhibited two good linear ranges during an incubation time of 10 min in the malathion concentration ranges of 0.02-50 ppb and 50-600 ppb, with a detection limit of 0.0135 ppb ( S/ N = 3). Overall, the prepared enzymatic biosensor showed high sensitivity in the rapid detection of Malathion and could be applied to detect pesticide residues in vegetable matter.

Superhydrophobic Ag nanostructures on polyaniline membranes with strong SERS enhancement.

PubMed

Liu, Weiyu; Miao, Peng; Xiong, Lu; Du, Yunchen; Han, Xijiang; Xu, Ping

2014-11-07

We demonstrate here a facile fabrication of n-dodecyl mercaptan-modified superhydrophobic Ag nanostructures on polyaniline membranes for molecular detection based on SERS technique, which combines the superhydrophobic condensation effect and the high enhancement factor. It is calculated that the as-fabricated superhydrophobic substrate can exhibit a 21-fold stronger molecular condensation, and thus further amplifies the SERS signal to achieve more sensitive detection. The detection limit of the target molecule, methylene blue (MB), on this superhydrophobic substrate can be 1 order of magnitude higher than that on the hydrophilic substrate. With high reproducibility, the feasibility of using this SERS-active superhydrophobic substrate for quantitative molecular detection is explored. A partial least squares (PLS) model was established for the quantification of MB by SERS, with correlation coefficient R(2) = 95.1% and root-mean-squared error of prediction (RMSEP) = 0.226. We believe this superhydrophobic SERS substrate can be widely used in trace analysis due to its facile fabrication, high signal reproducibility and promising SERS performance.

Carbon nanosphere-based fluorescence aptasensor for targeted detection of breast cancer cell MCF-7.

PubMed

Yang, Dandan; Liu, Mei; Xu, Jing; Yang, Chao; Wang, Xiaoxiao; Lou, Yongbing; He, Nongyue; Wang, Zhifei

2018-08-01

In this work, carbon nanosphere (CNS)-based fluorescence "turn off/on" aptasensor was developed for targeted detection of breast cancer cell MCF-7 by conjugation with FAM (a dye)-labeled mucin1 (MUC1) aptamer P0 (P0-FAM), which can recognize MUC1 protein overexpressed on the surface of MCF-7. Different from other carbon based fluorescence quenching materials, CNSs prepared by the carbonization of glucose not only have the high fluorescence quenching efficiency (98.8%), but also possess negligible cytotoxicity (in the concentration range of 0-1 mg/mL, which is 10 times higher than that of traditional carbon nanotubes or graphene oxide (0-100 µg/mL)). As for the detection of the mimic of the tumor antigen MUC1, the resulting fluorescence intensity increases nearly linearly in the range of 0-6 μM with the limit of detection (LOD) of 25 nM. Copyright © 2018 Elsevier B.V. All rights reserved.

Covalent organic framework as efficient desorption/ionization matrix for direct detection of small molecules by laser desorption/ionization mass spectrometry.

PubMed

Feng, Dan; Xia, Yan

2018-07-19

Covalent organic framework (COF) was explored as a novel matrix with a high desorption/ionization efficiency for direct detection of small molecules by laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS). By using COF as an LDI MS matrix, we could detect not only biological micro molecules such as amino acids and fatty acids, but also emerging environmental pollutants like bisphenol S (BPS) and pyrene. With COF as the matrix, higher desorption/ionization efficiency, and less background interference were achieved than the conventional organic matrices. Good salt tolerance (as high as 500 mM NaCl) and repeatability allowed the detection limit of amino acids was 90 fmol. In addition, COF matrix performed well for amino acids analysis in the honey sample. The ionization mechanism was also discussed. These results demonstrate that COF is a powerful matrix for small molecules analysis in real samples by MS. Copyright © 2018 Elsevier B.V. All rights reserved.

An active fluorescent probe based on aggregation-induced emission for intracellular bioimaging of Zn2+ and tracking of interactions with single-stranded DNA.

PubMed

Wen, Xiaoye; Wang, Qi; Fan, Zhefeng

2018-07-12

A novel dual-sensing fluorescence probe L was designed and synthesized for highly selective and sensitive detection of Zn 2+ and DNA. The probe L achieved a detection limit of 3.8 nM for Zn 2+ , which is lower than the acceptable level of Zn 2+ in living cells. The probe L displayed high selectivity toward Zn 2+ over other interference metal ions and amino acids. Moreover, the probe L displayed low cytotoxicity and good cell permeability, indicating its potential for detecting and bio-imaging of Zn 2+ . In addition, the probe L-Zn 2+ exhibited enhanced fluorescence signal for DNA detection through the metal-coordination interaction between Zn 2+ and DNA. The enhanced signal is higher than that of the classical ethidium bromide probe. The experiments in aqueous media verified the feasibility of applying probe L in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Assistive obstacle detection and navigation devices for vision-impaired users.

PubMed

Ong, S K; Zhang, J; Nee, A Y C

2013-09-01

Quality of life for the visually impaired is an urgent worldwide issue that needs to be addressed. Obstacle detection is one of the most important navigation tasks for the visually impaired. In this research, a novel range sensor placement scheme is proposed in this paper for the development of obstacle detection devices. Based on this scheme, two prototypes have been developed targeting at different user groups. This paper discusses the design issues, functional modules and the evaluation tests carried out for both prototypes. Implications for Rehabilitation Visual impairment problem is becoming more severe due to the worldwide ageing population. Individuals with visual impairment require assistance from assistive devices in daily navigation tasks. Traditional assistive devices that assist navigation may have certain drawbacks, such as the limited sensing range of a white cane. Obstacle detection devices applying the range sensor technology can identify road conditions with a higher sensing range to notify the users of potential dangers in advance.

Detection of incipient defects in cables by partial discharge signal analysis

NASA Astrophysics Data System (ADS)

Martzloff, F. D.; Simmon, E.; Steiner, J. P.; Vanbrunt, R. J.

1992-07-01

As one of the objectives of a program aimed at assessing test methods for in-situ detection of incipient defects in cables due to aging, a laboratory test system was implemented to demonstrate that the partial discharge analysis method can be successfully applied to low-voltage cables. Previous investigations generally involved cables rated 5 kV or higher, while the objective of the program focused on the lower voltages associated with the safety systems of nuclear power plants. The defect detection system implemented for the project was based on commercially available signal analysis hardware and software packages, customized for the specific purposes of the project. The test specimens included several cables of the type found in nuclear power plants, including artificial defects introduced at various points of the cable. The results indicate that indeed, partial discharge analysis is capable of detecting incipient defects in low-voltage cables. There are, however, some limitations of technical and non-technical nature that need further exploration before this method can be accepted in the industry.

Dynamic modeling of gearbox faults: A review

NASA Astrophysics Data System (ADS)

Liang, Xihui; Zuo, Ming J.; Feng, Zhipeng

2018-01-01

Gearbox is widely used in industrial and military applications. Due to high service load, harsh operating conditions or inevitable fatigue, faults may develop in gears. If the gear faults cannot be detected early, the health will continue to degrade, perhaps causing heavy economic loss or even catastrophe. Early fault detection and diagnosis allows properly scheduled shutdowns to prevent catastrophic failure and consequently result in a safer operation and higher cost reduction. Recently, many studies have been done to develop gearbox dynamic models with faults aiming to understand gear fault generation mechanism and then develop effective fault detection and diagnosis methods. This paper focuses on dynamics based gearbox fault modeling, detection and diagnosis. State-of-art and challenges are reviewed and discussed. This detailed literature review limits research results to the following fundamental yet key aspects: gear mesh stiffness evaluation, gearbox damage modeling and fault diagnosis techniques, gearbox transmission path modeling and method validation. In the end, a summary and some research prospects are presented.

Water vapour emission in vegetable fuel: absorption cell measurements and detection limits of our CO II Dial system

NASA Astrophysics Data System (ADS)

Bellecci, C.; De Leo, L.; Gaudio, P.; Gelfusa, M.; Lo Feudo, T.; Martellucci, S.; Richetta, M.

2006-09-01

Forest fires can be the cause of serious environmental and economic damages. For this reason a considerable effort has been directed toward the forest protection and fire fighting. In the early forest fire detection, Lidar technique present considerable advantages compared to the passive detection methods based on infrared cameras currently in common use, due its higher sensitivity and ability to accurately locate the fire. The combustion phase of the vegetable matter causes a great amount of water vapour emission, thus the water molecule behaviour will be studied to obtain a fire detection system ready and efficient also before the flame propagation. A first evaluation of increment of the water vapour concentration compared to standard one will be estimated by a numerical simulation. These results will be compared with the experimental measurements carried out into a cell with a CO II Dial system, burning different kinds of vegetable fuel. Our results and their comparison will be reported in this paper.

Occurrence of bisphenol A in surface water, drinking water and plasma from Malaysia with exposure assessment from consumption of drinking water.

PubMed

Santhi, V A; Sakai, N; Ahmad, E D; Mustafa, A M

2012-06-15

This study investigated the level of bisphenol A (BPA) in surface water used as potable water, drinking water (tap and bottled mineral water) and human plasma in the Langat River basin, Malaysia. BPA was present in 93% of the surface water samples at levels ranging from below limit of quantification (LOQ; 1.3 ng/L) to 215 ng/L while six fold higher levels were detected in samples collected near industrial and municipal sewage treatment plant outlets. Low levels of BPA were detected in most of the drinking water samples. BPA in tap water ranged from 3.5 to 59.8 ng/L with the highest levels detected in samples collected from taps connected to PVC pipes and water filter devices. Bottled mineral water had lower levels of BPA (3.3±2.6 ng/L) although samples stored in poor storage condition had significantly higher levels (11.3±5.3 ng/L). Meanwhile, only 17% of the plasma samples had detectable levels of BPA ranging from 0.81 to 3.65 ng/mL. The study shows that BPA is a ubiquitous contaminant in surface, tap and bottled mineral water. However, exposure to BPA from drinking water is very low and is less than 0.01% of the tolerable daily intake (TDI). Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of multi- and hyperspectral imaging data of leaf rust infected wheat plants

NASA Astrophysics Data System (ADS)

Franke, Jonas; Menz, Gunter; Oerke, Erich-Christian; Rascher, Uwe

2005-10-01

In the context of precision agriculture, several recent studies have focused on detecting crop stress caused by pathogenic fungi. For this purpose, several sensor systems have been used to develop in-field-detection systems or to test possible applications of remote sensing. The objective of this research was to evaluate the potential of different sensor systems for multitemporal monitoring of leaf rust (puccinia recondita) infected wheat crops, with the aim of early detection of infected stands. A comparison between a hyperspectral (120 spectral bands) and a multispectral (3 spectral bands) imaging system shows the benefits and limitations of each approach. Reflectance data of leaf rust infected and fungicide treated control wheat stand boxes (1sqm each) were collected before and until 17 days after inoculation. Plants were grown under controlled conditions in the greenhouse and measurements were taken under consistent illumination conditions. The results of mixture tuned matched filtering analysis showed the suitability of hyperspectral data for early discrimination of leaf rust infected wheat crops due to their higher spectral sensitivity. Five days after inoculation leaf rust infected leaves were detected, although only slight visual symptoms appeared. A clear discrimination between infected and control stands was possible. Multispectral data showed a higher sensitivity to external factors like illumination conditions, causing poor classification accuracy. Nevertheless, if these factors could get under control, even multispectral data may serve a good indicator for infection severity.

Search times and probability of detection in time-limited search

NASA Astrophysics Data System (ADS)

Wilson, David; Devitt, Nicole; Maurer, Tana

2005-05-01

When modeling the search and target acquisition process, probability of detection as a function of time is important to war games and physical entity simulations. Recent US Army RDECOM CERDEC Night Vision and Electronics Sensor Directorate modeling of search and detection has focused on time-limited search. Developing the relationship between detection probability and time of search as a differential equation is explored. One of the parameters in the current formula for probability of detection in time-limited search corresponds to the mean time to detect in time-unlimited search. However, the mean time to detect in time-limited search is shorter than the mean time to detect in time-unlimited search and the relationship between them is a mathematical relationship between these two mean times. This simple relationship is derived.

Based on time and spatial-resolved SERS mapping strategies for detection of pesticides.

PubMed

Ma, Bingbing; Li, Pan; Yang, Liangbao; Liu, Jinhuai

2015-08-15

For the sensitive and convenient detection of pesticides, several sensing methods and materials have been widely explored. However, it is still a challenge to obtain sensitive, simple detection techniques for pesticides. Here, the simple and sensitive Time-resolved SERS mapping (T-SERS) and Spatial-resolved SERS mapping (S-SERS) are presented for detection of pesticides by using Au@Ag NPs as SERS substrate. The Time-resolved SERS mapping (T-SERS) is based on state translation nanoparticles from the wet state to the dry state to realize SERS measurements. During the SERS measurement, adhesive force drives the particles closer together and then average interparticle gap becomes smaller. Following, air then begins to intersperse into the liquid network and the particles are held together by adhesive forces at the solid-liquid-air interface. In the late stage of water evaporation, all particles are uniformly distributed. Thus, so called hotspots matrix that can hold hotspots between every two adjacent particles in efficient space with minimal polydispersity of particle size are achieved, accompanying the red-shift of surface plasmon peak and appearance of an optimal SPR resonated sharply with excitation wavelength. Here, we found that the T-SERS method exhibits the detection limits of 1-2 orders of magnitude higher than that of S-SERS. On the other hand, the T-SERS is very simple method with high detection sensitivity, better reproducibility (RSD=10.8%) and is beneficial to construction of a calibration curve in comparison with that of Spatial-resolved SERS mapping (S-SERS). Most importantly, as a result of its remarkable sensitivity, T-SERS mapping strategies have been applied to detection of several pesticides and the detect limit can down to 1nM for paraoxon, 0.5nM for sumithion. In short, T-SERS mapping measurement promises to open a market for SERS practical detection with prominent advantages. Copyright © 2015. Published by Elsevier B.V.

Heavy metal(loid)s and organic contaminants in groundwater in the Pearl River Delta that has undergone three decades of urbanization and industrialization: Distributions, sources, and driving forces.

PubMed

Huang, Guanxing; Zhang, Ming; Liu, Chunyan; Li, Liangping; Chen, Zongyu

2018-09-01

Urbanization and industrialization have increased groundwater resource demands, and may drive the change of heavy metal(loid)s and organic chemicals in groundwater in the Pearl River Delta (PRD), southern China. Thus, a comprehensive understanding of the distributions, sources, and driving forces of heavy metal(loid)s and organic chemicals in groundwater in the PRD is vital for water resource management in this region. In this study, eight heavy metal(loid)s and fifty-five organic chemicals in groundwater across the PRD were investigated. The results show that undrinkable groundwater related to heavy metal(loid)s was mainly due to high concentrations of Fe (19.3%) and As (6.8%). Eighteen organic contaminants were detected in groundwater in the PRD, where the most frequently detected organic contaminant was naphthalene, and its detection rate was 2.51%. In 5.3% of all groundwater samples, one or more organic contaminants were found. All detected organic contaminants, except ones without allowable limits, in groundwater were at concentrations below allowable limits of China. The mean concentrations of heavy metal(loid)s in granular aquifers were higher than those in fissured and karst aquifers, especially for Fe and As. Except Se, the mean concentrations of other heavy metal(loid)s and the frequency of detection of organic contaminants in groundwater in urbanized and peri-urban areas were higher than those in non-urbanized areas, especially for Hg, Co, and organic contaminants. Fe, As, and Se in groundwater mainly originated from the release of Fe/As/Se rich sediments. The former two were driven by reduction reactions, while the latter was driven by oxidation resulting from the infiltration of NO 3 - . In contrast, other five heavy metal(loid)s and organic contaminants in groundwater mainly originated from the anthropogenic sources, such as the infiltration of industrial sewage. It is evident that urbanization and industrialization are two powerful driving forces for heavy metal(loid)s and organic contaminants in groundwater in the PRD. Copyright © 2018 Elsevier B.V. All rights reserved.

New Fluorescent Nanoparticles for Ultrasensitive Detection of Nucleic Acids by Optical Methods.

PubMed

Westergaard Mulberg, Mads; Taskova, Maria; Thomsen, Rasmus P; Okholm, Anders H; Kjems, Jørgen; Astakhova, Kira

2017-08-17

For decades the detection of nucleic acids and their interactions at low abundances has been a challenging task that has thus far been solved by enzymatic target amplification. In this work we aimed at developing efficient tools for amplification-free nucleic acid detection, which resulted in the synthesis of new fluorescent nanoparticles. Here, the fluorescent nanoparticles were made by simple and inexpensive radical emulsion polymerization of butyl acrylate in the presence of fluorescent dyes and additional functionalization reagents. This provided ultra-bright macrofluorophores of 9-84 nm mean diameter, modified with additional alkyne and amino groups for bioconjugation. By using click and NHS chemistries, the new nanoparticles were attached to target-specific DNA probes that were used in fluorimetry and fluorescence microscopy. Overall, these fluorescent nanoparticles and their oligonucleotide derivatives have higher photostability, brighter fluorescence and hence dramatically lower limits of target detection than the individual organic dyes. These properties make them useful in approaches directed towards ultrasensitive detection of nucleic acids, in particular for imaging and in vitro diagnostics of DNA. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Shrink-induced graphene sensor for alpha-fetoprotein detection with low-cost self-assembly and label-free assay

NASA Astrophysics Data System (ADS)

Sando, Shota; Zhang, Bo; Cui, Tianhong

2017-12-01

Combination of shrink induced nano-composites technique and layer-by-layer (LbL) self-assembled graphene challenges controlling surface morphology. Adjusting shrink temperature achieves tunability on graphene surface morphology on shape memory polymers, and it promises to be an alternative in fields of high-surface-area conductors and molecular detection. In this study, self-assembled graphene on a shrink polymer substrate exhibits nanowrinkles after heating. Induced nanowrinkles on graphene with different shrink temperature shows distinct surface roughness and wettability. As a result, it becomes more hydrophilic with higher shrink temperatures. The tunable wettability promises to be utilized in, for example, microfluidic devices. The graphene on shrink polymer also exhibits capability of being used in sensing applications for pH and alpha-fetoprotein (AFP) detection with advantages of label free and low cost, due to self-assembly technique, easy functionalization, and antigen-antibody reaction on graphene surface. The detection limit of AFP detection is down to 1 pg/mL, and therefore the sensor also has a significant potential for biosensing as it relies on low-cost self-assembly and label-free assay.

Development of Loop-Mediated Isothermal Amplification (LAMP) Assay for Rapid Detection of Cannabis sativa.

PubMed

Kitamura, Masashi; Aragane, Masako; Nakamura, Kou; Watanabe, Kazuhito; Sasaki, Yohei

2016-07-01

In many parts of the world, the possession and cultivation of Cannabis sativa L. are restricted by law. As chemical or morphological analyses cannot identify the plant in some cases, a simple yet accurate DNA-based method for identifying C. sativa is desired. We have developed a loop-mediated isothermal amplification (LAMP) assay for the rapid identification of C. sativa. By optimizing the conditions for the LAMP reaction that targets a highly conserved region of tetrahydrocannabinolic acid (THCA) synthase gene, C. sativa was identified within 50 min at 60-66°C. The detection limit was the same as or higher than that of conventional PCR. The LAMP assay detected all 21 specimens of C. sativa, showing high specificity. Using a simple protocol, the identification of C. sativa could be accomplished within 90 min from sample treatment to detection without use of special equipment. A rapid, sensitive, highly specific, and convenient method for detecting and identifying C. sativa has been developed and is applicable to forensic investigations and industrial quality control.

A highly sensitive and selective diagnostic assay based on virus nanoparticles

NASA Astrophysics Data System (ADS)

Park, Jin-Seung; Cho, Moon Kyu; Lee, Eun Jung; Ahn, Keum-Young; Lee, Kyung Eun; Jung, Jae Hun; Cho, Yunjung; Han, Sung-Sik; Kim, Young Keun; Lee, Jeewon

2009-04-01

Early detection of the protein marker troponin I in patients with a higher risk of acute myocardial infarction can reduce the risk of death from heart attacks. Most troponin assays are currently based on the conventional enzyme linked immunosorbent assay and have detection limits in the nano- and picomolar range. Here, we show that by combining viral nanoparticles, which are engineered to have dual affinity for troponin antibodies and nickel, with three-dimensional nanostructures including nickel nanohairs, we can detect troponin levels in human serum samples that are six to seven orders of magnitude lower than those detectable using conventional enzyme linked immunosorbent assays. The viral nanoparticle helps to orient the antibodies for maximum capture of the troponin markers. High densities of antibodies on the surfaces of the nanoparticles and nanohairs lead to greater binding of the troponin markers, which significantly enhances detection sensitivities. The nickel nanohairs are re-useable and can reproducibly differentiate healthy serum from unhealthy ones. We expect other viral nanoparticles to form similar highly sensitive diagnostic assays for a variety of other protein markers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hull, G; Zaitseva, N; Cherepy, N

Efficient, readily-available, low-cost, high-energy neutron detectors can play a central role in detecting illicit nuclear weapons since neutrons are a strong indication for the presence of fissile material such as Plutonium and Highly-Enriched Uranium. The main challenge in detecting fast neutrons consists in the discrimination of the signal from the gamma radiation background. At present, the only well-investigated organic crystal scintillator for fast neutron detection, in a n/{gamma} mixed field, is stilbene, which while offering good pulse shape discrimination, is not widely used because of its limited availability and high cost. In this work we report the results of ourmore » studies made with a number of new organic crystals, which exhibit pulse shape discrimination for detection of fast neutrons. In particular 1,1,4,4-tetraphenyl-1,3-butadiene features a light yield higher than anthracene and a Figure of Merit (FOM) for the pulse shape discrimination better than stilbene. New crystals are good candidates for the low-cost solution growth method, thus representing promising organic scintillators for widespread deployment for high-energy neutron detection.« less

Serum Acetaminophen Protein Adduct Concentrations in Pediatric Emergency Department Patients.

PubMed

Heard, Kennon; Anderson, Victoria; Dart, Richard C; Kile, Deidre; Lavonas, Eric J; Green, Jody L

2017-04-01

Acetaminophen toxicity is a common cause of pediatric liver failure. The diagnosis may be limited by the short window of detection of acetaminophen in serum. Recently acetaminophen protein adducts (APAP-CYS) have been used as a biomarker with a longer duration of detection. The objective of this study was to describe the serum concentrations of APAP-CYS in pediatric patients with and without reported therapeutic acetaminophen exposure. A cross-sectional study of children age 1 to <12 years presenting to a pediatric emergency department. Subjects were stratified by recent acetaminophen use and had serum APAP-CYS measured using LC/MS. One hundred patients were enrolled. All of the patients whose caregivers denied acetaminophen exposure had nondetectable APAP-CYS. Fifty-two percent of subjects who were reported to have taken acetaminophen in the preceding 2 weeks had detectable serum APAP-CYS. The APAP-CYS concentrations were positively correlated with higher overall dose and more recent ingestion. APAP-CYS is detectable in the majority of children taking acetaminophen and not detected in the majority of children who are not exposed to acetaminophen.

Shot noise limited detection of OH using the technique of laser induced fluorescence

NASA Technical Reports Server (NTRS)

Bakalyar, D. M.; Davis, L. I., Jr.; Guo, C.; James, J. V.; Kakos, S.; Morris, P. T.; Wang, C. C.

1984-01-01

Nearly shot-noise limited detection of OH using the technique of laser-induced fluorescence is reported. A LIDAR configuration is used to excite fluorescence in a large volume and a narrow-bandwidth interference filter provides spectral discrimination. This arrangement alleviates the effect of ozone interference and facilitates image processing at relatively close distances. The detection limit is determined mainly by the shot-noise of the solar background. Ground-based measurements in Dearborn indicate a detection limit of better than 1 x 10 to the 6th power OH/cubic cm over a forty-minute acquisition period. Under favorable conditions, a comparable detection limit was also observed for airborne measurements.

Shot noise limited detection of OH using the technique of laser-induced fluorescence

NASA Technical Reports Server (NTRS)

Bakalyar, D. M.; Davis, L. I., Jr.; Guo, C.; James, J. V.; Wang, C. C.; Kakos, S.; Morris, P. T.

1984-01-01

Nearly shot-noise limited detection of OH using the technique of laser-induced fluorescence is reported. A LIDAR configuration is used to excite fluoresence in a large volume and a narrow-bandwidth interference filter provides spectral discrimination. This arrangement alleviates the effect of ozone interference and facilitates image processing at relatively close distances. The detection limit is determined mainly by the short-noise of the solar background. Ground-based measurements in Dearborn indicate a detection limit of better than 1 x 10 to the 6th power OH/cubic cm over a forty-minute acquisition period. Under favorable conditions, a comparable detection limit was also observed for airborne measurements.

Discovering the Highest Energy Neutrinos Using a Radio Phased Array

NASA Astrophysics Data System (ADS)

Vieregg, Abigail

2018-06-01

The detection of high energy neutrinos is an important step toward understanding the most energetic cosmic accelerators and would enable tests of fundamental physics at energy scales that cannot easily be achieved on Earth. IceCube has detected astrophysical neutrinos at lower energies, and at higher energies the best limits to date on the flux comes from IceCube and the ANITA experiment, a NASA balloon-borne radio telescope designed to detect coherent radio Cherenkov emission from cosmogenic ultra-high energy neutrinos. I will discuss a new radio phased array design that will push the achievable sensitivity and lower the energy threshold. I will discuss the initial deployment and performance of an 8-channel system in a ground-based experiment at the South Pole (ARA), and the plans for scaling to O(100) channels and lowering the power consumption for future balloon-borne and ground-based applications.

Blending DNA binding dyes to improve detection in real-time PCR.

PubMed

Jansson, Linda; Koliana, Marianne; Sidstedt, Maja; Hedman, Johannes

2017-03-01

The success of real-time PCR (qPCR) analysis is partly limited by the presence of inhibitory compounds in the nucleic acid samples. For example, humic acid (HA) from soil and aqueous sediment interferes with amplification and also quenches the fluorescence of double-stranded (ds) DNA binding dyes, thus hindering amplicon detection. We aimed to counteract the HA fluorescence quenching effect by blending complementary dsDNA binding dyes, thereby elevating the dye saturation levels and increasing the fluorescence signals. A blend of the four dyes EvaGreen, ResoLight, SYBR Green and SYTO9 gave significantly higher fluorescence intensities in the presence and absence of HA, compared with the dyes applied separately and two-dye blends. We propose blending of dyes as a generally applicable means for elevating qPCR fluorescence signals and thus enabling detection in the presence of quenching substances.

I Spy with My Little Eye: Jurors' Detection of Internal Validity Threats in Expert Evidence

PubMed Central

McAuliff, Bradley D.; Duckworth, Tejah D.

2010-01-01

This experiment examined whether jury-eligible community members (N = 223) were able to detect internally invalid psychological science presented at trial. Participants read a simulated child sexual abuse case in which the defense expert described a study he had conducted on witness memory and suggestibility. We varied the study's internal validity (valid, missing control group, confound, and experimenter bias) and publication status (published, unpublished). Expert evidence quality ratings were higher for the valid versus missing control group version only. Publication increased ratings of defendant guilt when the study was missing a control group. Variations in internal validity did not influence perceptions of child victim credibility or police interview quality. Participants' limited detection of internal validity threats underscores the need to examine the effectiveness of traditional legal safeguards against junk science in court and improve the scientific reasoning ability of lay people and legal professionals. PMID:20162342

Combined acquisition technique (CAT) for neuroimaging of multiple sclerosis at low specific absorption rates (SAR).

PubMed

Biller, Armin; Choli, Morwan; Blaimer, Martin; Breuer, Felix A; Jakob, Peter M; Bartsch, Andreas J

2014-01-01

To compare a novel combined acquisition technique (CAT) of turbo-spin-echo (TSE) and echo-planar-imaging (EPI) with conventional TSE. CAT reduces the electromagnetic energy load transmitted for spin excitation. This radiofrequency (RF) burden is limited by the specific absorption rate (SAR) for patient safety. SAR limits restrict high-field MRI applications, in particular. The study was approved by the local Medical Ethics Committee. Written informed consent was obtained from all participants. T2- and PD-weighted brain images of n = 40 Multiple Sclerosis (MS) patients were acquired by CAT and TSE at 3 Tesla. Lesions were recorded by two blinded, board-certificated neuroradiologists. Diagnostic equivalence of CAT and TSE to detect MS lesions was evaluated along with their SAR, sound pressure level (SPL) and sensations of acoustic noise, heating, vibration and peripheral nerve stimulation. Every MS lesion revealed on TSE was detected by CAT according to both raters (Cohen's kappa of within-rater/across-CAT/TSE lesion detection κCAT = 1.00, at an inter-rater lesion detection agreement of κLES = 0.82). CAT reduced the SAR burden significantly compared to TSE (p<0.001). Mean SAR differences between TSE and CAT were 29.0 (± 5.7) % for the T2-contrast and 32.7 (± 21.9) % for the PD-contrast (expressed as percentages of the effective SAR limit of 3.2 W/kg for head examinations). Average SPL of CAT was no louder than during TSE. Sensations of CAT- vs. TSE-induced heating, noise and scanning vibrations did not differ. T2-/PD-CAT is diagnostically equivalent to TSE for MS lesion detection yet substantially reduces the RF exposure. Such SAR reduction facilitates high-field MRI applications at 3 Tesla or above and corresponding protocol standardizations but CAT can also be used to scan faster, at higher resolution or with more slices. According to our data, CAT is no more uncomfortable than TSE scanning.

Interferon-γ–Inducible Protein 10 (IP-10) as a Screening Tool to Optimize Human Immunodeficiency Virus RNA Monitoring in Resource-Limited Settings

PubMed Central

Pastor, Lucía; Casellas, Aina; Carrillo, Jorge; Maculuve, Sonia; Jairoce, Chenjerai; Paredes, Roger; Blanco, Julià; Naniche, Denise

2017-01-01

Abstract Background Achieving effective antiretroviral treatment (ART) monitoring is a key determinant to ensure viral suppression and reach the UNAIDS 90-90-90 targets. The gold standard for detecting virological failure is plasma human immunodeficiency virus (HIV) RNA (viral load [VL]) testing; however, its availability is very limited in low-income countries due to cost and operational constraints. Methods HIV-1–infected adults on first-line ART attending routine visits at the Manhiça District Hospital, Mozambique, were previously evaluated for virologic failure. Plasma levels of interferon-γ–inducible protein 10 (IP-10) were quantified by enzyme-linked immunosorbent assay. Logistic regression was used to build an IP-10–based model able to identify individuals with VL >150 copies/mL. From the 316 individuals analyzed, 253 (80%) were used for model training and 63 (20%) for validation. Receiver operating characteristic curves were employed to evaluate model prediction. Results From the individuals included in the training set, 34% had detectable VL. Mean age was 41 years, 70% were females, and median time on ART was 3.4 years. IP-10 levels were significantly higher in subjects with detectable VL (108.2 pg/mL) as compared to those with undetectable VL (38.0 pg/mL) (P < .0001, U test). IP-10 univariate model demonstrated high classification performance (area under the curve = 0.85 [95% confidence interval {CI}, .80–.90]). Using a cutoff value of IP-10 ≥44.2 pg/mL, the model identified detectable VL with 91.9% sensitivity (95% CI, 83.9%–96.7%) and 59.9% specificity (95% CI, 52.0%–67.4%), values confirmed in the validation set. Conclusions IP-10 is an accurate biomarker to screen individuals on ART for detectable viremia. Further studies should evaluate the benefits of IP-10 as a triage approach to monitor ART in resource-limited settings. PMID:29020145

Electroreduction-based electrochemical-enzymatic redox cycling for the detection of cancer antigen 15-3 using graphene oxide-modified indium-tin oxide electrodes.

PubMed

Park, Seonhwa; Singh, Amardeep; Kim, Sinyoung; Yang, Haesik

2014-02-04

We compare herein biosensing performance of two electroreduction-based electrochemical-enzymatic (EN) redox-cycling schemes [the redox cycling combined with simultaneous enzymatic amplification (one-enzyme scheme) and the redox cycling combined with preceding enzymatic amplification (two-enzyme scheme)]. To minimize unwanted side reactions in the two-enzyme scheme, β-galactosidase (Gal) and tyrosinase (Tyr) are selected as an enzyme label and a redox enzyme, respectively, and Tyr is selected as a redox enzyme label in the one-enzyme scheme. The signal amplification in the one-enzyme scheme consists of (i) enzymatic oxidation of catechol into o-benzoquinone by Tyr and (ii) electroreduction-based EN redox cycling of o-benzoquinone. The signal amplification in the two-enzyme scheme consists of (i) enzymatic conversion of phenyl β-d-galactopyranoside into phenol by Gal, (ii) enzymatic oxidation of phenol into catechol by Tyr, and (iii) electroreduction-based EN redox cycling of o-benzoquinone including further enzymatic oxidation of catechol to o-benzoquinone by Tyr. Graphene oxide-modified indium-tin oxide (GO/ITO) electrodes, simply prepared by immersing ITO electrodes in a GO-dispersed aqueous solution, are used to obtain better electrocatalytic activities toward o-benzoquinone reduction than bare ITO electrodes. The detection limits for mouse IgG, measured with GO/ITO electrodes, are lower than when measured with bare ITO electrodes. Importantly, the detection of mouse IgG using the two-enzyme scheme allows lower detection limits than that using the one-enzyme scheme, because the former gives higher signal levels at low target concentrations although the former gives lower signal levels at high concentrations. The detection limit for cancer antigen (CA) 15-3, a biomarker of breast cancer, measured using the two-enzyme scheme and GO/ITO electrodes is ca. 0.1 U/mL, indicating that the immunosensor is highly sensitive.

Detection and Identification: Instrumentation and Calibration for Air/Liquid/Surface-borne Nanoscale Particles

NASA Astrophysics Data System (ADS)

Ling, Tsz Yan; Zuo, Zhili; Pui, David Y. H.

2013-04-01

Nanoscale particles can be found in the air-borne, liquid-borne and surface-borne dispersed phases. Measurement techniques for nanoscale particles in all three dispersed phases are needed for the environmental, health and safety studies of nanomaterials. We present our studies on connecting the nanoparticle measurements in different phases to enhance the characterization capability. Microscopy analysis for particle morphology can be performed by depositing air-borne or liquid-borne nanoparticles on surfaces. Detection limit and measurement resolution of the liquid-borne nanoparticles can be enhanced by aerosolizing them and taking advantage of the well-developed air-borne particle analyzers. Sampling electrically classified air-borne virus particles with a gelatin filter provides higher collection efficiency than a liquid impinger.

Aptamer Based Microsphere Biosensor for Thrombin Detection

PubMed Central

Zhu, Hongying; Suter, Jonathan D.; White, Ian M.; Fan, Xudong

2006-01-01

We have developed an optical microsphere resonator biosensor using aptamer as receptor for the measurement of the important biomolecule thrombin. The sphere surface is modified with anti-thrombin aptamer, which has excellent binding affinity and selectivity for thrombin. Binding of the thrombin at the sphere surface is monitored by the spectral position of the microsphere's whispering gallery mode resonances. A detection limit on the order of 1 NIH Unit/mL is demonstrated. Control experiments with non-aptamer oligonucleotide and BSA are also carried out to confirm the specific binding between aptamer and thrombin. We expect that this demonstration will lead to the development of highly sensitive biomarker sensors based on aptamer with lower cost and higher throughput than current technology.

Dichotic listening in patients with splenial and nonsplenial callosal lesions.

PubMed

Pollmann, Stefan; Maertens, Marianne; von Cramon, D Yves; Lepsien, Joeran; Hugdahl, Kenneth

2002-01-01

The authors found splenial lesions to be associated with left ear suppression in dichotic listening of consonant-vowel syllables. This was found in both a rapid presentation dichotic monitoring task and a standard dichotic listening task, ruling out attentional limitations in the processing of high stimulus loads as a confounding factor. Moreover, directed attention to the left ear did not improve left ear target detection in the patients, independent of callosal lesion location. The authors' data may indicate that auditory callosal fibers pass through the splenium more posterior than previously thought. However, further studies should investigate whether callosal fibers between primary and secondary auditory cortices, or between higher level multimodal cortices, are vital for the detection of left ear targets in dichotic listening.

Laser frequency-offset locking based on the frequency modulation spectroscopy with higher harmonic detection

NASA Astrophysics Data System (ADS)

Wang, Anqi; Meng, Zhixin; Feng, Yanying

2017-10-01

We design a fiber electro-optic modulator (FEOM)-based laser frequency-offset locking system using frequency modulation spectroscopy (FMS) with the 3F modulation. The modulation signal and the frequency-offset control signal are simultaneously loaded on the FEOM by a mixer in order to suppress the frequency and power jitter caused by internal modulation on the current or piezoelectric ceramic transducer (PZT). It is expected to accomplish a fast locking, a widely tunable frequency-offset, a sensitive and rapid detection of narrow spectral features with the 3F modulation. The laser frequency fluctuation is limited to +/-1MHz and its overlapping Allan deviation is around 10-12 in twenty minutes, which successfully meets the requirements of the cold atom interferometer.

Measurement-Device-Independent Quantum Key Distribution over 200 km

NASA Astrophysics Data System (ADS)

Tang, Yan-Lin; Yin, Hua-Lei; Chen, Si-Jing; Liu, Yang; Zhang, Wei-Jun; Jiang, Xiao; Zhang, Lu; Wang, Jian; You, Li-Xing; Guan, Jian-Yu; Yang, Dong-Xu; Wang, Zhen; Liang, Hao; Zhang, Zhen; Zhou, Nan; Ma, Xiongfeng; Chen, Teng-Yun; Zhang, Qiang; Pan, Jian-Wei

2014-11-01

Measurement-device-independent quantum key distribution (MDIQKD) protocol is immune to all attacks on detection and guarantees the information-theoretical security even with imperfect single-photon detectors. Recently, several proof-of-principle demonstrations of MDIQKD have been achieved. Those experiments, although novel, are implemented through limited distance with a key rate less than 0.1 bit /s . Here, by developing a 75 MHz clock rate fully automatic and highly stable system and superconducting nanowire single-photon detectors with detection efficiencies of more than 40%, we extend the secure transmission distance of MDIQKD to 200 km and achieve a secure key rate 3 orders of magnitude higher. These results pave the way towards a quantum network with measurement-device-independent security.

Summary of vulnerability related technologies based on machine learning

NASA Astrophysics Data System (ADS)

Zhao, Lei; Chen, Zhihao; Jia, Qiong

2018-04-01

As the scale of information system increases by an order of magnitude, the complexity of system software is getting higher. The vulnerability interaction from design, development and deployment to implementation stages greatly increases the risk of the entire information system being attacked successfully. Considering the limitations and lags of the existing mainstream security vulnerability detection techniques, this paper summarizes the development and current status of related technologies based on the machine learning methods applied to deal with massive and irregular data, and handling security vulnerabilities.

Enabling fast charging – A battery technology gap assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmed, Shabbir; Bloom, Ira; Jansen, Andrew N.

The battery technology literature is reviewed, with an emphasis on key elements that limit extreme fast charging. Key gaps in existing elements of the technology are presented as well as developmental needs. Among these needs are advanced models and methods to detect and prevent lithium plating; new positive-electrode materials which are less prone to stress-induced failure; better electrode designs to accommodate very rapid diffusion in and out of the electrode; and thermal management and pack designs to accommodate the higher operating voltage.

Enabling fast charging – A battery technology gap assessment

DOE PAGES

Ahmed, Shabbir; Bloom, Ira; Jansen, Andrew N.; ...

2017-10-23

The battery technology literature is reviewed, with an emphasis on key elements that limit extreme fast charging. Key gaps in existing elements of the technology are presented as well as developmental needs. Among these needs are advanced models and methods to detect and prevent lithium plating; new positive-electrode materials which are less prone to stress-induced failure; better electrode designs to accommodate very rapid diffusion in and out of the electrode; and thermal management and pack designs to accommodate the higher operating voltage.

Re-evaluation of groundwater monitoring data for glyphosate and bentazone by taking detection limits into account.

PubMed

Hansen, Claus Toni; Ritz, Christian; Gerhard, Daniel; Jensen, Jens Erik; Streibig, Jens Carl

2015-12-01

Current regulatory assessment of pesticide contamination of Danish groundwater is exclusively based on samples with pesticide concentrations above detection limit. Here we demonstrate that a realistic quantification of pesticide contamination requires the inclusion of "non-detect" samples i.e. samples with concentrations below the detection limit, as left-censored observations. The median calculated pesticide concentrations are shown to be reduced 10(4) to 10(5) fold for two representative herbicides (glyphosate and bentazone) relative to the median concentrations based upon observations above detection limits alone. Copyright © 2015 Elsevier B.V. All rights reserved.

Elucidation of the role of biological factors and device design in cerebral NIRS using an in vivo hematoma model based on high-intensity focused ultrasound

NASA Astrophysics Data System (ADS)

Wang, Jianting; Huang, Stanley; Myers, Matthew; Chen, Yu; Welle, Cristin; Pfefer, Joshua

2016-03-01

Near-Infrared Spectroscopy (NIRS) is an emerging medical countermeasure for rapid, field detection of hematomas caused by traumatic brain injury (TBI). Bench and animal tests to determine NIRS sensitivity and specificity are needed. However, current animal models involving non-invasively induced, localized neural damage are limited. We investigated an in vivo murine hematoma model in which cerebral hemorrhage was induced noninvasively by high-intensity focused ultrasound (HIFU) with calibrated positioning and parameters. To characterize the morphology of induced hematomas, we used skull-intact histological evaluation. A multi-wavelength fiber-optic NIRS system with three source-detector separation distances was used to detect hematoma A 1.1 MHz transducer produced consistent small-to-medium hematoma localized to a single hemisphere, along with bruising of the scalp, with a low mortality rate. A 220 kHz transducer produced larger, more diffuse hematomas, with higher variability in size and a correspondingly higher mortality rate. No skin bruising or blood accumulation between the skin and skull was observed following injury application with the 220 kHz transducer. Histological analysis showed higher sensitivity for larger hematomas (>4x4 mm2). NIRS optical density change after HIFU was able to detect all hematomas, with sensitivity dependent on wavelength and separation distance. While improvements in methods for validating cerebral blood distribution are needed, the HIFU hematoma model provided useful insights that will inform development of biologically relevant, performance test methods for cerebral NIRS systems.

Double Hits in Schizophrenia.

PubMed

Vorstman, Jacob A S; Olde Loohuis, Loes M; Kahn, René S; Ophoff, Roel A

2018-05-14

The co-occurrence of a Copy Number Variant (CNV) and a functional variant on the other allele may be a relevant genetic mechanism in schizophrenia. We hypothesized that the cumulative burden of such double hits - in particular those composed of a deletion and a coding single nucleotide variation (SNV) - is increased in patients with schizophrenia.We combined CNV data with coding variants data in 795 patients with schizophrenia and 474 controls. To limit false CNV-detection, only CNVs called only by two algorithms we included. CNV-affected genes were subsequently examined for coding SNVs, which we termed "CNV-SNVs". Correcting for total queried sequence, we assessed the CNV-SNV-burden and the combined predicted deleterious effect. We estimated p-values by permutation of the phenotype.We detected 105 CNV-SNVs; 67 in duplicated and 38 in deleted genic sequence. While the difference in CNV-SNVs rates was not significant, the combined deleteriousness inferred by CNV-SNVs in deleted sequence was almost fourfold higher in cases compared to controls (nominal p = 0.009). This effect may be driven by a higher number of CNV-SNVs and/or by a higher degree of predicted deleteriousness of CNV-SNVs. No such effect was observed for duplications.We provide early evidence that deletions co-occurring with a functional variant may be relevant, albeit of modest impact, for the genetic etiology of schizophrenia. Large-scale consortium studies are required to validate our findings. Sequence-based analyses would provide the best resolution for detection of CNVs as well as coding variants genome-wide.

[Features of arterial blood pressure in elderly persons of different ethnic groups in Yakutsk].

PubMed

Nikitin, Iu P; Tatarinova, O V; Neustroeva, V N; Shcherbakova, L V; Sidorov, A S

2013-01-01

The differences in arterial blood pressure in the sample of population in the age of 60 and older of different ethnic groups in Yakutsk, as well as its connection with the other cardiovascular diseases risk factors have been analyzed. It was shown that the average values of systolic and diastolic blood pressure in subsample of the Yakuts appeared to be lower than in Caucasoid gerontic persons. The average values of systolic arterial blood pressure both in the Yakuts and in the Caucasoids were detected higher than normal values in all age-dependent subgroups. The average values of diastolic blood pressure in both ethnic groups were within the limits of high normal level. From 60 to 90 years and older the decrease in systolic and diastolic arterial blood pressure was detected; it was more marked in Caucasoid gerontic persons. The average values of pulse pressure in the Yakuts and in the Caucasoids appeared to be higher than the existing standard and didn't have any differences in ethnic groups. In both ethnical subsamples, pulse pressure values increase was observed in persons of 60-89 years old and its decrease after 90. Persons with overweight, obesity, central (abdominal) obesity, dyslypoproteidemias irrespective of belonging to ethnical group were characterized as having higher levels of arterial blood pressure. Statistically significant differences in the levels of arterial blood pressure in the Yakuts and in the Caucasoids depending on hyperglycemia, smoking, the presence of burdened anamnesis, educational level, marital status was not detected.

Clinical value of jointly detection serum lactate dehydrogenase/pleural fluid adenosine deaminase and pleural fluid carcinoembryonic antigen in the identification of malignant pleural effusion.

PubMed

Zhang, Fan; Hu, Lijuan; Wang, Junjun; Chen, Jian; Chen, Jie; Wang, Yumin

2017-09-01

Limited data are available for the diagnostic value, and for the diagnostic sensitivity and specificity of joint detection of serum lactate dehydrogenase (sLDH)/pleural fluid adenosine deaminase (pADA) and pleural fluid carcinoembryonic antigen (pCEA) in malignant pleural effusion (MPE). We collected 987 pleural effusion specimens (of which 318 were malignant pleural effusion, 374 were tubercular pleural effusion, and 295 were parapneumonic effusion specimens) from the First Affiliated Hospital of Wenzhou Medical University from July 2012 to March 2016. The pADA, sLDH, pleural fluid LDH (pLDH), serum C-reactive protein (sCRP), pleural fluid protein, pCEA, white blood cell (WBC), and red blood cell (RBC) were analyzed, and the clinical data of each group were collected for statistical analysis. The level of sLDH/pADA, pCEA, and RBC from the MPE group was markedly higher than the tuberculosis pleural effusion (TB) group (Mann-Whitney U=28422.000, 9278.000, 30518, P=.000, .000, .000) and the parapneumonic pleural fluid group (Mann-Whitney U=5972.500, 7113.000, 36750.500, P=.000, .000, .000). The receiver operating characteristic curve ROC showed that the area under the ROC curve (AUC) (=0.924, 0.841) of pCEA and sLDH/pADA (cutoff=4.9, 10.6) were significantly higher than other markers for the diagnosis of MPE. Thus, joint detection of pCEA and sLDH/pADA suggested that the sensitivity, specificity, and AUC was 0.94, 81.70, and 94.32 at the cutoff 0.16 and diagnostic performance was higher than pCEA or sLDH/pADA. Joint detection of sLDH/pADA and pCEA can be used as a good indicator for the identification of benign and MPE with higher sensitivity and specificity than pCEA or sLDH/pADA. © 2016 Wiley Periodicals, Inc.

Development and Comparison of Two Assay Formats for Parallel Detection of Four Biothreat Pathogens by Using Suspension Microarrays

PubMed Central

Janse, Ingmar; Bok, Jasper M.; Hamidjaja, Raditijo A.; Hodemaekers, Hennie M.; van Rotterdam, Bart J.

2012-01-01

Microarrays provide a powerful analytical tool for the simultaneous detection of multiple pathogens. We developed diagnostic suspension microarrays for sensitive and specific detection of the biothreat pathogens Bacillus anthracis, Yersinia pestis, Francisella tularensis and Coxiella burnetii. Two assay chemistries for amplification and labeling were developed, one method using direct hybridization and the other using target-specific primer extension, combined with hybridization to universal arrays. Asymmetric PCR products for both assay chemistries were produced by using a multiplex asymmetric PCR amplifying 16 DNA signatures (16-plex). The performances of both assay chemistries were compared and their advantages and disadvantages are discussed. The developed microarrays detected multiple signature sequences and an internal control which made it possible to confidently identify the targeted pathogens and assess their virulence potential. The microarrays were highly specific and detected various strains of the targeted pathogens. Detection limits for the different pathogen signatures were similar or slightly higher compared to real-time PCR. Probit analysis showed that even a few genomic copies could be detected with 95% confidence. The microarrays detected DNA from different pathogens mixed in different ratios and from spiked or naturally contaminated samples. The assays that were developed have a potential for application in surveillance and diagnostics. PMID:22355407

Development and comparison of two assay formats for parallel detection of four biothreat pathogens by using suspension microarrays.

PubMed

Janse, Ingmar; Bok, Jasper M; Hamidjaja, Raditijo A; Hodemaekers, Hennie M; van Rotterdam, Bart J

2012-01-01

Microarrays provide a powerful analytical tool for the simultaneous detection of multiple pathogens. We developed diagnostic suspension microarrays for sensitive and specific detection of the biothreat pathogens Bacillus anthracis, Yersinia pestis, Francisella tularensis and Coxiella burnetii. Two assay chemistries for amplification and labeling were developed, one method using direct hybridization and the other using target-specific primer extension, combined with hybridization to universal arrays. Asymmetric PCR products for both assay chemistries were produced by using a multiplex asymmetric PCR amplifying 16 DNA signatures (16-plex). The performances of both assay chemistries were compared and their advantages and disadvantages are discussed. The developed microarrays detected multiple signature sequences and an internal control which made it possible to confidently identify the targeted pathogens and assess their virulence potential. The microarrays were highly specific and detected various strains of the targeted pathogens. Detection limits for the different pathogen signatures were similar or slightly higher compared to real-time PCR. Probit analysis showed that even a few genomic copies could be detected with 95% confidence. The microarrays detected DNA from different pathogens mixed in different ratios and from spiked or naturally contaminated samples. The assays that were developed have a potential for application in surveillance and diagnostics.

Impedance biosensor based on interdigitated electrode array for detection of E.coli O157:H7 in food products

NASA Astrophysics Data System (ADS)

Ghosh Dastider, Shibajyoti; Barizuddin, Syed; Dweik, Majed; Almasri, Mahmoud F.

2012-05-01

An impedance biosensor was designed, fabricated and tested for detection of viable Escherichia coli O157:H7 in food samples. This device consists of interdigitated microelectrode array (IDEA) fabricated using thin layer of sputtered gold, embedded under a polydimethylsiloxane (PDMS) microchannel. The array of electrodes is designed to detect viable EColi in different food products. The active surface area of the detection array was modified using goat anti-E.coli polyclonal IgG antibody. Contaminated food samples were tested by infusing the supernatant containing bacteria over the IDEA's, through the microchannel. Antibody-antigen binding on the electrodes results in impedance change. Four serial concentrations of E.coli contaminated food samples (3x102 CFUmL-1 to 3x105 CFUmL-1) were tested. The biosensor successfully detected the E.coli samples, with the lower detection limit being 3x103 CFUmL-1 (up to 3cells/μl). Comparing the test results with an IDEA impedance biosensor without microchannel (published elsewhere) indicates that this biosensor have two order of magnitude times higher sensitivity. The proposed biosensor provides qualitative and quantitative detection, and potentially could be used for detection of other type of bacteria by immobilizing the specific type of antibody.

Characterization of emissions from a desktop 3D printer and indoor air measurements in office settings.

PubMed

Steinle, Patrick

2016-01-01

Emissions from a desktop 3D printer based on fused deposition modeling (FDM) technology were measured in a test chamber and indoor air was monitored in office settings. Ultrafine aerosol (UFA) emissions were higher while printing a standard object with polylactic acid (PLA) than with acrylonitrile butadiene styrene (ABS) polymer (2.1 × 10(9) vs. 2.4 × 10(8) particles/min). Prolonged use of the printer led to higher emission rates (factor 2 with PLA and 4 with ABS, measured after seven months of occasional use). UFA consisted mainly of volatile droplets, and some small (100-300 nm diameter) iron containing and soot-like particles were found. Emissions of inhalable and respirable dust were below the limit of detection (LOD) when measured gravimetrically, and only slightly higher than background when measured with an aerosol spectrometer. Emissions of volatile organic compounds (VOC) were in the range of 10 µg/min. Styrene accounted for more than 50% of total VOC emitted when printing with ABS; for PLA, methyl methacrylate (MMA, 37% of TVOC) was detected as the predominant compound. Two polycyclic aromatic hydrocarbons (PAH), fluoranthene and pyrene, were observed in very low amounts. All other analyzed PAH, as well as inorganic gases and metal emissions except iron (Fe) and zinc (Zn), were below the LOD or did not differ from background without printing. A single 3D print (165 min) in a large, well-ventilated office did not significantly increase the UFA and VOC concentrations, whereas these were readily detectable in a small, unventilated room, with UFA concentrations increasing by 2,000 particles/cm(3) and MMA reaching a peak of 21 µg/m(3) and still being detectable in the room even 20 hr after printing.

Supervised detection of exoplanets in high-contrast imaging sequences

NASA Astrophysics Data System (ADS)

Gomez Gonzalez, C. A.; Absil, O.; Van Droogenbroeck, M.

2018-06-01

Context. Post-processing algorithms play a key role in pushing the detection limits of high-contrast imaging (HCI) instruments. State-of-the-art image processing approaches for HCI enable the production of science-ready images relying on unsupervised learning techniques, such as low-rank approximations, for generating a model point spread function (PSF) and subtracting the residual starlight and speckle noise. Aims: In order to maximize the detection rate of HCI instruments and survey campaigns, advanced algorithms with higher sensitivities to faint companions are needed, especially for the speckle-dominated innermost region of the images. Methods: We propose a reformulation of the exoplanet detection task (for ADI sequences) that builds on well-established machine learning techniques to take HCI post-processing from an unsupervised to a supervised learning context. In this new framework, we present algorithmic solutions using two different discriminative models: SODIRF (random forests) and SODINN (neural networks). We test these algorithms on real ADI datasets from VLT/NACO and VLT/SPHERE HCI instruments. We then assess their performances by injecting fake companions and using receiver operating characteristic analysis. This is done in comparison with state-of-the-art ADI algorithms, such as ADI principal component analysis (ADI-PCA). Results: This study shows the improved sensitivity versus specificity trade-off of the proposed supervised detection approach. At the diffraction limit, SODINN improves the true positive rate by a factor ranging from 2 to 10 (depending on the dataset and angular separation) with respect to ADI-PCA when working at the same false-positive level. Conclusions: The proposed supervised detection framework outperforms state-of-the-art techniques in the task of discriminating planet signal from speckles. In addition, it offers the possibility of re-processing existing HCI databases to maximize their scientific return and potentially improve the demographics of directly imaged exoplanets.

Microplate magnetic chemiluminescence immunoassay for detecting urinary survivin in bladder cancer.

PubMed

Chang, Yanli; Xu, Jianjun; Zhang, Qingyun

2017-10-01

Survivin is a tumor marker for bladder cancer; however the role of urinary survivin levels has not been fully elucidated due to the limitations of current detection methods. Based on two survivin-specific monoclonal antibodies (McAbs) already confirmed through enzyme linked immunosorbent assays, the present study aimed to establish a microplate magnetic chemiluminescence immunoassay (CLIA) for the detection of urinary survivin levels and evaluate its application for the diagnosis of patients with bladder cancer. Horseradish peroxidase and biotin conjugates were used to label two different anti-survivin McAbs, respectively. The labeled antibodies combined with survivin to form a sandwiched immune complex. The streptavidin magnetic particles (MPs) served as the solid phase and the separator. The relevant parameters involved in the immunoassay, including the immunoassay reagents used and the physicochemical parameters were optimized. Then, urine samples from 130 patients with bladder cancer and 113 healthy controls were detected, and analyzed using the established method. The method was linear to 1,000 ng/ml survivin with a detection limit of 0.83 ng/ml. The intra- and inter-assay coefficients of variation were <8, and <11%, respectively. The concentration of diluted survivin and the dilution ratios gave a linear correlation of 0.9989. The results demonstrated that the urinary survivin levels in patients with bladder cancer were significantly higher (P<0.001) compared with that in healthy controls. At a survivin concentration of 2.0884 ng/ml, the sensitivity and specificity were 86.9 and 61.9%, respectively. Furthermore, the urinary survivin levels were positively correlated with metastatic stage, histological stage and recurrence (P<0.01). In conclusion, the present study preliminarily proposed a microplate magnetic CLIA for survivin detection and further evaluated the value of urinary survivin as a diagnostic marker for bladder cancer.

Microplate magnetic chemiluminescence immunoassay for detecting urinary survivin in bladder cancer

PubMed Central

Chang, Yanli; Xu, Jianjun; Zhang, Qingyun

2017-01-01

Survivin is a tumor marker for bladder cancer; however the role of urinary survivin levels has not been fully elucidated due to the limitations of current detection methods. Based on two survivin-specific monoclonal antibodies (McAbs) already confirmed through enzyme linked immunosorbent assays, the present study aimed to establish a microplate magnetic chemiluminescence immunoassay (CLIA) for the detection of urinary survivin levels and evaluate its application for the diagnosis of patients with bladder cancer. Horseradish peroxidase and biotin conjugates were used to label two different anti-survivin McAbs, respectively. The labeled antibodies combined with survivin to form a sandwiched immune complex. The streptavidin magnetic particles (MPs) served as the solid phase and the separator. The relevant parameters involved in the immunoassay, including the immunoassay reagents used and the physicochemical parameters were optimized. Then, urine samples from 130 patients with bladder cancer and 113 healthy controls were detected, and analyzed using the established method. The method was linear to 1,000 ng/ml survivin with a detection limit of 0.83 ng/ml. The intra- and inter-assay coefficients of variation were <8, and <11%, respectively. The concentration of diluted survivin and the dilution ratios gave a linear correlation of 0.9989. The results demonstrated that the urinary survivin levels in patients with bladder cancer were significantly higher (P<0.001) compared with that in healthy controls. At a survivin concentration of 2.0884 ng/ml, the sensitivity and specificity were 86.9 and 61.9%, respectively. Furthermore, the urinary survivin levels were positively correlated with metastatic stage, histological stage and recurrence (P<0.01). In conclusion, the present study preliminarily proposed a microplate magnetic CLIA for survivin detection and further evaluated the value of urinary survivin as a diagnostic marker for bladder cancer. PMID:28943911

EARLY SCIENCE WITH THE KOREAN VLBI NETWORK: THE QCAL-1 43 GHz CALIBRATOR SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrov, Leonid; Lee, Sang-Sung; Kim, Jongsoo

2012-11-01

This paper presents the catalog of correlated flux densities in three ranges of baseline projection lengths of 637 sources from a 43 GHz (Q band) survey observed with the Korean VLBI Network. Of them, 14 objects used as calibrators were previously observed, but 623 sources have not been observed before in the Q band with very long baseline interferometry (VLBI). The goal of this work in the early science phase of the new VLBI array is twofold: to evaluate the performance of the new instrument that operates in a frequency range of 22-129 GHz and to build a list ofmore » objects that can be used as targets and as calibrators. We have observed the list of 799 target sources with declinations down to -40 Degree-Sign . Among them, 724 were observed before with VLBI at 22 GHz and had correlated flux densities greater than 200 mJy. The overall detection rate is 78%. The detection limit, defined as the minimum flux density for a source to be detected with 90% probability in a single observation, was in the range of 115-180 mJy depending on declination. However, some sources as weak as 70 mJy have been detected. Of 623 detected sources, 33 objects are detected for the first time in VLBI mode. We determined their coordinates with a median formal uncertainty of 20 mas. The results of this work set the basis for future efforts to build the complete flux-limited sample of extragalactic sources at frequencies of 22 GHz and higher at 3/4 of the celestial sphere.« less

Detection limits of 405 nm and 633 nm excited PpIX fluorescence for brain tumor detection during stereotactic biopsy

NASA Astrophysics Data System (ADS)

Markwardt, Niklas; Götz, Marcus; Haj-Hosseini, Neda; Hollnburger, Bastian; Sroka, Ronald; Stepp, Herbert; Zelenkov, Petr; Rühm, Adrian

2016-04-01

5-aminolevulinic-acid-(5-ALA)-induced protoporphyrin IX (PpIX) fluorescence may be used to improve stereotactic brain tumor biopsies. In this study, the sensitivity of PpIX-based tumor detection has been investigated for two potential excitation wavelengths (405 nm, 633 nm). Using a 200 μm fiber in contact with semi-infinite optical phantoms containing ink and Lipovenös, PpIX detection limits of 4.0 nM and 200 nM (relating to 1 mW excitation power) were determined for 405 nm and 633 nm excitation, respectively. Hence, typical PpIX concentrations in glioblastomas of a few μM should be well detectable with both wavelengths. Additionally, blood layers of selected thicknesses were placed between fiber and phantom. Red excitation was shown to be considerably less affected by blood interference: A 50 μm blood layer, for instance, blocked the 405- nm-excited fluorescence completely, but reduced the 633-nm-excited signal by less than 50%. Ray tracing simulations demonstrated that - without blood layer - the sensitivity advantage of 405 nm rises for decreasing fluorescent volume from 50-fold to a maximum of 100-fold. However, at a tumor volume of 1 mm3, which is a typical biopsy sample size, the 633-nm-excited fluorescence signal is only reduced by about 10%. Further simulations revealed that with increasing fiber-tumor distance, the signal drops faster for 405 nm. This reduces the risk of detecting tumor tissue outside the needle's coverage, but diminishes the overlap between optically and mechanically sampled volumes. While 405 nm generally offers a higher sensitivity, 633 nm is more sensitive to distant tumors and considerably superior in case of blood-covered tumor tissue.

Fabrication of MoS2 biosensor to detect lower-concentrated area of biological molecules(Conference Presentation)

NASA Astrophysics Data System (ADS)

Yang, Erika; Ryu, Byunghoon; Nam, Hongsuk; Liang, Xiaogan

2017-03-01

Two dimensional layered transition metal dichalcogenides (TMDC) materials have the growing potential to upstage graphene in the next generation of biosensors in detecting lower-concentrated areas of biomolecules. The current gold-standard detection method is the enzyme-linked immunosorbent assay (ELISA), an immunological assay technique that makes use of an enzyme bonded to a particular antibody or antigen. However, this technique is not only bulky, labor-intensive, and time extensive, but more importantly, the ELISA has relatively low detection limits of only 600 femtomolar (fM). In this work, for the first time, we present a novel flexible, sensitive MoS2 (molybdenum disulfide) biosensor, as shown in Figure 1, composed of few-layer of MoS2 as the channel material, and flexible polyimide as the substrate. In order to nano-fabricate this flexible biosensor, we mechanically transferred a few layers of MoS2 onto the flexible substrate polyimide and photolithography to create a patterning on the surface, and as a result, we were able to create a transistor that used MoS2 as its conductance channel. We successfully fabricated this MoS2 biosensor onto a flexible polyimide substrate. Furthermore, the fabricated flexible MoS2 biosensor can be utilized for quantifying the time-dependent reaction kinetics of streptavidin-biotin binding. Figure 2 shows the transfer characteristics of flexible MoS2 biosensors measured under different concentrations of streptavidin. The flexible MoS2 biosensor could illustrate a faster detection time in matters of minutes, and higher sensitivity with detection limits as low as 10 fM. Time versus equilibrium constants will be presented in details.

Part-per-trillion level detection of estradiol by competitive fluorescence immunoassay using DNA/dye conjugate as antibody multiple labels.

PubMed

Zhu, Shengchao; Zhang, Qin; Guo, Liang-Hong

2008-08-22

Fluorescent organic dyes are currently the standard signal-generating labels used in microarray quantification. However, new labeling strategies are needed to meet the demand for high sensitivity in the detection of low-abundance proteins and small molecules. In this report, a long-chain DNA/dye conjugate was used to attach multiple fluorescence labels on antibodies to improve signal intensity and immunoassay sensitivity. Compared with the 30 base-pair (bp) oligonucleotide used in our previous work [Q. Zhang, L.-H. Guo, Bioconjugate Chem. 18 (2007) 1668-1672], conjugation of a 219 bp DNA in solution with a fluorescent DNA binder SYBR Green I resulted in more than sixfold increase in signal intensity, consistent with the increase in bp number. In a direct immunoassay for the detection of goat anti-mouse IgG in a mouse IgG-coated 96-well plate, the long DNA conjugate label also produced higher fluorescence than the short one, accompanied by about 15-fold improvement in the detection limit. To demonstrate its advantage in real applications, the DNA/dye conjugate was employed in the competitive immunoassay of 17beta-estradiol, a clinically and environmentally important analyte. The biotin-terminated DNA was attached to biotinylated anti-estradiol antibody through the biotin/streptavidin/biotin bridge after the immuno-reaction was completed, followed by conjugation with SYBR Green I. The limit of detection for 17beta-estradiol is 1.9 pg mL(-1), which is 200-fold lower than the assay using fluorescein-labeled antibodies. The new multiple labeling strategy uses readily available reagents, and is also compatible with current biochip platform. It has great potential in the sensitive detection of protein and antibody microarrays.

Development of a rapid assay to detect the dinoflagellate Amyloodinium ocellatum using loop-mediated isothermal amplification (LAMP).

PubMed

Picón-Camacho, Sara M; Thompson, William P; Blaylock, Reginald B; Lotz, Jeffrey M

2013-09-23

Amyloodinium ocellatum is a highly pathogenic dinoflagellate parasite with global distribution that causes high mortalities in the culture of tropical and sub-tropical marine and estuarine fishes. Diagnosis typically occurs through gross examination following the onset of morbidity, at which point treatment is of limited benefit. In the present study, a new molecular diagnostic tool for the rapid detection of A. ocellatum (AO) was developed using the loop-mediated isothermal amplification method (LAMP). The AO-LAMP assay designed is highly specific using a set of four primers - two outer and two inner primers targeting six different regions on the 5' end of the Small Subunit rDNA region (SSU rDNA) of A. ocellatum. The AO-LAMP assay, optimized for 25-30 min at 62°C, amplified the DNA from A. ocellatum extracted from both water and gill tissue samples and did not amplify DNA from four closely related dinoflagellate sp ecies. The detection limit of the AO-LAMP assay was 10 fg, exceptionally higher than the conventional PCR (1 pg). In addition, the standardized AO-LAMP assay was capable of detecting single tomonts and trophonts; the assay was not affected by the presence of possible inhibitory substances present in environmental water samples or gill samples. The AO-LAMP assay developed in the present study provides a novel useful tool for the simple, rapid and sensitive detection of A. ocellatum in water and gill tissue samples, which could assist in the early detection and improved control of A. ocellatum infections in aquaculture systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Droplet digital PCR (ddPCR) vs quantitative real-time PCR (qPCR) approach for detection and quantification of Merkel cell polyomavirus (MCPyV) DNA in formalin fixed paraffin embedded (FFPE) cutaneous biopsies.

PubMed

Arvia, Rosaria; Sollai, Mauro; Pierucci, Federica; Urso, Carmelo; Massi, Daniela; Zakrzewska, Krystyna

2017-08-01

Merkel cell polyomavirus (MCPyV) is associated with Merkel cell carcinoma and high viral load in the skin was proposed as a risk factor for the occurrence of this tumour. MCPyV DNA was detected, with lower frequency, in different skin cancers but since the viral load was usually low, the real prevalence of viral DNA could be underestimated. To evaluate the performance of two assays (qPCR and ddPCR) for MCPyV detection and quantification in formalin fixed paraffin embedded (FFPE) tissue samples. Both assays were designed to simultaneous detection and quantification of both MCPyV as well as house-keeping DNA in clinical samples. The performance of MCPyV quantification was investigated using serial dilutions of cloned target DNA. We also evaluated the applicability of both tests for the analysis of 76 FFPE cutaneous biopsies. The two approaches resulted equivalent with regard to the reproducibility and repeatability and showed a high degree of linearity in the dynamic range tested in the present study. Moreover, qPCR was able to quantify ≥10 5 copies per reaction, while the upper limit of ddPCR was 10 4 copies. There was not significant difference between viral load measured by the two methods The detection limit of both tests was 0,15 copies per reaction, however, the number of positive samples obtained by ddPCR was higher than that obtained by qPCR (45% and 37% respectively). The ddPCR represents a better method for detection of MCPyV in FFPE biopsies, mostly these containing low copies number of viral genome. Copyright © 2017 Elsevier B.V. All rights reserved.

[Detection of intraorbital foreign material using MDCT].

PubMed

Hoffstetter, P; Friedrich, C; Framme, C; Hoffstetter, M; Zorger, N; Stierstorfer, K; Ross, C; Uller, W; Müller-Wille, R; Rennert, J; Jung, E M; Schreyer, A G

2011-06-01

To judge the possibilities of detection of orbital foreign bodies in multidetector CT (MDCT) with a focus on glass slivers. Experimental systematic measuring of Hounsfield Units (HU) of 20 different materials, containing 16 different types of glass with 4 different types of ophthalmic lenses among them. The measurements were performed using a standardized protocol with an orbita phantom being scanned with 16-slice MDCT. Using the resulting density values, the smallest detectable volume was calculated. Using this data we produced slivers of 5 different glass types in the sub-millimeter range and calculated their volume. Those micro-slivers underwent another CT scan using the same protocol as mentioned above to experimentally discern and confirm the detection limit for micro-slivers made of different materials. Glass has comparatively high density values of at least 2000 HU. The density of glasses with strong refraction is significantly higher and reaches up to 12 400 HU. We calculated a minimum detectable volume of 0.07 mm (3) for glass with a density of 2000 HU. Only glass slivers with a density higher than 8300 HU were experimentally detectable in the sub-millimeter range up to a volume as small as 0.01 mm (3). Less dense glass slivers could not be seen, even though their volume was above the theoretically calculated threshold for detection. Due to its high density of at least 2000 HU, glass is usually easily recognizable as an orbital foreign body. The detection threshold depends on the object's density and size and can be as low as 0.01 mm (3) in the case of glass with strong refraction and thus high density. The detection of glass as an orbital foreign body seems to be secure for slivers with a volume of at least 0.2 mm (3) for all types of glass. © Georg Thieme Verlag KG Stuttgart · New York.

STUDYING FAINT ULTRA-HARD X-RAY EMISSION FROM AGN IN GOALS LIRGS WITH SWIFT/BAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koss, Michael; Casey, Caitlin M.; Mushotzky, Richard

2013-03-10

We present the first analysis of the all-sky Swift Burst Alert Telescope (BAT) ultra-hard X-ray (14-195 keV) data for a targeted list of objects. We find that the BAT data can be studied at three-times-fainter limits than in previous blind detection catalogs based on prior knowledge of source positions and using smaller energy ranges for source detection. We determine the active galactic nucleus (AGN) fraction in 134 nearby (z < 0.05) luminous infrared galaxies (LIRGs) from the GOALS sample. We find that LIRGs have a higher detection frequency than galaxies matched in stellar mass and redshift at 14-195 keV andmore » 24-35 keV. In agreement with work at other wavelengths, the AGN detection fraction increases strongly at high IR luminosity with half of the high-luminosity LIRGs (50%, 6/12, log L{sub IR}/L{sub Sun} > 11.8) detected. The BAT AGN classification shows 97% (37/38) agreement with Chandra and XMM-Newton AGN classification using hardness ratios or detection of an iron K{alpha} line. This confirms our statistical analysis and supports the use of the Swift/BAT all-sky survey to study fainter populations of any category of sources in the ultra-hard X-ray band. BAT AGNs in LIRGs tend to show higher column densities with 40% {+-} 9% showing 14-195 keV/2-10 keV hardness flux ratios suggestive of high or Compton-thick column densities (log N{sub H} > 24 cm{sup -2}), compared to only 12% {+-} 5% of non-LIRG BAT AGNs. We also find that using specific energy ranges of the BAT detector can yield additional sources over total band detections with 24% (5/21) of detections in LIRGs at 24-35 keV not detected at 14-195 keV.« less

Any impact of blips and low-level viraemia episodes among HIV-infected patients with sustained virological suppression on ART?

PubMed

Pernas, Berta; Grandal, Marta; Pertega, Sonia; Cañizares, Angelina; Castro-Iglesias, Ángeles; Mena, Álvaro; Rodriguez-Osorio, Iria; Tabernilla, Andrés; Pedreira, José D; Poveda, Eva

2016-04-01

The objective of this study was to evaluate the prevalence of blips and risk of virological failure (VF) among HIV-infected patients with sustained virological suppression (HIV-RNA <50 copies/mL) on ART. Newly diagnosed (2004-13) HIV-infected patients with sustained virological suppression on ART (minimum follow-up of 3 months) were identified. Risk of VF was evaluated according to different plasma HIV-RNA quantification values based on the limits of quantification/detection of current commercial assays (20 copies/mL). Kaplan-Meier and Cox proportional hazards models were used to compare the cumulative incidence of VF. A total of 565 newly diagnosed HIV-infected patients were identified: 453 started ART and 354 achieved virological suppression. Prevalence of blips (isolated HIV-RNA ranging from 50 to 200 copies/mL) and VF (HIV-RNA ≥50 copies/mL) was 22.7% and 8.8%, respectively (mean follow-up of 42 months). Multivariate analysis identified differences between HIV-RNA values as an independent predictor of VF (P = 0.008); risk of VF was higher for patients with blips [HR 2.500 (95% CI 0.524-11.926)] and for those with at least three consecutive detected, but not quantified, HIV-RNA determinations (HIV-RNA <20 copies/mL) [HR 3.813 (95% CI 0.675-21.535)]. Moreover, only HIV-infected patients with at least three consecutive detected, but not quantified, HIV-RNA determinations showed a higher probability of virological rebound with >200 copies/mL [33.7% at 24 and 60 months versus <5% for other HIV-RNA values; HR 6.943 (0.728-66.261), P = 0.092]. Blips are frequent (22.7%) among HIV-infected patients with sustained virological suppression on ART. HIV patients with blips and at least three consecutive detected, but not quantified, HIV-RNA determinations (<20 copies/mL) had a higher risk of VF. These findings highlight the relevance of maintaining HIV-RNA levels below the limits of quantification of current assays (<20 copies/mL). © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Identifying the underlying causes of biological instability in a full-scale drinking water supply system.

PubMed

Nescerecka, Alina; Juhna, Talis; Hammes, Frederik

2018-05-15

Changes in bacterial concentration and composition in drinking water during distribution are often attributed to biological (in)stability. Here we assessed temporal biological stability in a full-scale distribution network (DN) supplied with different types of source water: treated and chlorinated surface water and chlorinated groundwater produced at three water treatment plants (WTP). Monitoring was performed weekly during 12 months in two locations in the DN. Flow cytometric total and intact cell concentration (ICC) measurements showed considerable seasonal fluctuations, which were different for two locations. ICC varied between 0.1-3.75 × 10 5  cells mL -1 and 0.69-4.37 × 10 5  cells mL -1 at two locations respectively, with ICC increases attributed to temperature-dependent bacterial growth during distribution. Chlorinated water from the different WTP was further analysed with a modified growth potential method, identifying primary and secondary growth limiting compounds. It was observed that bacterial growth in the surface water sample after chlorination was primarily inhibited by phosphorus limitation and secondly by organic carbon limitation, while carbon was limiting in the chlorinated groundwater samples. However, the ratio of available nutrients changed during distribution, and together with disinfection residual decay, this resulted in higher bacterial growth potential detected in the DN than at the WTP. In this study, bacterial growth was found to be higher (i) at higher water temperatures, (ii) in samples with lower chlorine residuals and (iii) in samples with less nutrient (carbon, phosphorus, nitrogen, iron) limitation, while this was significantly different between the samples of different origin. Thus drinking water microbiological quality and biological stability could change during different seasons, and the extent of these changes depends on water temperature, the water source and treatment. Furthermore, differences in primary growth limiting nutrients in different water sources could contribute to biological instability in the network, where mixing occurs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Size-tunable copper nanocluster aggregates and their application in hydrogen sulfide sensing on paper-based devices

NASA Astrophysics Data System (ADS)

Chen, Po-Cheng; Li, Yu-Chi; Ma, Jia-Yin; Huang, Jia-Yu; Chen, Chien-Fu; Chang, Huan-Tsung

2016-04-01

Polystyrene sulfonate (PSS), a strong polyelectrolyte, was used to prepare red photoluminescent PSS-penicillamine (PA) copper (Cu) nanoclusters (NC) aggregates, which displayed high selectivity and sensitivity to the detection of hydrogen sulfide (H2S). The size of the PSS-PA-Cu NC aggregates could be readily controlled from 5.5 μm to 173 nm using different concentrations of PSS, which enabled better dispersity and higher sensitivity towards H2S. PSS-PA-Cu NC aggregates provided rapid H2S detection by using the strong Cu-S interaction to quench NC photoluminescence as a sensing mechanism. As a result, a detection limit of 650 nM, which is lower than the maximum level permitted in drinking water by the World Health Organization, was achieved for the analysis of H2S in spring-water samples. Moreover, highly dispersed PSS-PA-Cu NC aggregates could be incorporated into a plate-format paper-based analytical device which enables ultra-low sample volumes (5 μL) and feature shorter analysis times (30 min) compared to conventional solution-based methods. The advantages of low reagent consumption, rapid result readout, limited equipment, and long-term storage make this platform sensitive and simple enough to use without specialized training in resource constrained settings.

Optimization of chemical and instrumental parameters in hydride generation laser-induced breakdown spectrometry for the determination of arsenic, antimony, lead and germanium in aqueous samples.

PubMed

Yeşiller, Semira Unal; Yalçın, Serife

2013-04-03

A laser induced breakdown spectrometry hyphenated with on-line continuous flow hydride generation sample introduction system, HG-LIBS, has been used for the determination of arsenic, antimony, lead and germanium in aqueous environments. Optimum chemical and instrumental parameters governing chemical hydride generation, laser plasma formation and detection were investigated for each element under argon and nitrogen atmosphere. Arsenic, antimony and germanium have presented strong enhancement in signal strength under argon atmosphere while lead has shown no sensitivity to ambient gas type. Detection limits of 1.1 mg L(-1), 1.0 mg L(-1), 1.3 mg L(-1) and 0.2 mg L(-1) were obtained for As, Sb, Pb and Ge, respectively. Up to 77 times enhancement in detection limit of Pb were obtained, compared to the result obtained from the direct analysis of liquids by LIBS. Applicability of the technique to real water samples was tested through spiking experiments and recoveries higher than 80% were obtained. Results demonstrate that, HG-LIBS approach is suitable for quantitative analysis of toxic elements and sufficiently fast for real time continuous monitoring in aqueous environments. Copyright © 2013 Elsevier B.V. All rights reserved.

Measurements of peroxyacetyl nitrate (PAN) and NO2 at the South Pacific Ocean

NASA Astrophysics Data System (ADS)

Yeon, J.; Song, D.; Lee, J. S.; Rhee, T. S.; Park, K.; Lee, G.

2014-12-01

We measured peroxyacetyl nitrate (PAN) and NO2 in remote marine boundary area during the SHIPPO (Shipborne Pole to Pole Observation). The measurements were made on the R/V Araon from Christ church, New Zealand to Gwangyang, South Korea along the western Pacific Ocean from March 30th to April 25th, 2014. Both PAN and NO2 were analyzed every 2 minute by a fast chromatograph with luminol-based chemiluminescence detection. In order to improve their detection limits, random noise from PMT has been successfully reduced by ensembled chromatograms with every 30 samples. Additionally, we replaced Nylon membrane surface with reflective aluminum surface and applied the new Luminol solution, which enhanced the signals significantly with detection limits of 6 pptv and 40 ppbv for PAN and NO2, respectively. Average concentrations of PAN and NO2 were 8 pptv for PAN and 80 pptv for NO2 during the experiment. The back trajectory analysis showed that the directly influenced air masses from anthropogenic activities were rare except the latitudes higher than 20°N. Relatively good correlations between PAN and NO2 were consistently observed, while PAN and O3 were not clearly correlated except in the air masses recently originated from land masses.

Simple and sensitive determination of five quinolones in food by liquid chromatography with fluorescence detection.

PubMed

Ramos, Macarena; Aranda, Angela; Garcia, Elena; Reuvers, Thea; Hooghuis, Henny

2003-06-15

A simple and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the determination of five different quinolones: enrofloxacin, ciprofloxacin, sarafloxacin, oxolinic acid and flumequine in pork and salmon muscle. The method includes one extraction and clean-up step for the five quinolones together which are detected in two separated HPLC runs by means of their fluorescence. The proposed analytical method involves homogenizing of the tissue sample with 0.05 M phosphate buffer, pH 7.4 and clean-up by Discovery DS-18 cartridges. For chromatographic separation a Symmetry C(18) column is used in two different runs: (1) ciprofloxacin, enrofloxacin and sarafloxacin with acetonitrile-0.02 M phosphate buffer pH 3.0 (18:82) as mobile phase and the detector at excitation wavelength: 280 nm and emission wavelength 450 nm; and (2) oxolinic acid and flumequine with acetonitrile-0.02 M phosphate buffer pH 3.0 (34:66) as mobile phase and excitation wavelength: 312 nm and emission wavelength: 366 nm. Detection limit was as low as 5 ng g(-1), except for sarafloxacin which had a limit of 10 ng g(-1). Standard curves using blank muscle tissues spiked at different levels showed a good linear correlation coefficient, r(2) higher than 0.999 for all quinolones.

Development and evaluation of a novel high-throughput image-based fluorescent neutralization test for detection of Zika virus infection.

PubMed

Koishi, Andrea Cristine; Suzukawa, Andréia Akemi; Zanluca, Camila; Camacho, Daria Elena; Comach, Guillermo; Duarte Dos Santos, Claudia Nunes

2018-03-01

Zika virus (ZIKV) is an emerging arbovirus belonging to the genus flavivirus that comprises other important public health viruses, such as dengue (DENV) and yellow fever (YFV). In general, ZIKV infection is a self-limiting disease, however cases of Guillain-Barré syndrome and congenital brain abnormalities in newborn infants have been reported. Diagnosing ZIKV infection remains a challenge, as viral RNA detection is only applicable until a few days after the onset of symptoms. After that, serological tests must be applied, and, as expected, high cross-reactivity between ZIKV and other flavivirus serology is observed. Plaque reduction neutralization test (PRNT) is indicated to confirm positive samples for being more specific, however it is laborious intensive and time consuming, representing a major bottleneck for patient diagnosis. To overcome this limitation, we developed a high-throughput image-based fluorescent neutralization test for ZIKV infection by serological detection. Using 226 human specimens, we showed that the new test presented higher throughput than traditional PRNT, maintaining the correlation between results. Furthermore, when tested with dengue virus samples, it showed 50.53% less cross reactivity than MAC-ELISA. This fluorescent neutralization test could be used for clinical diagnosis confirmation of ZIKV infection, as well as for vaccine clinical trials and seroprevalence studies.

The separation of 99Tc from low and medium-level radioactive wastes and its determination by inductively coupled plasma mass spectrometry.

PubMed

Hepiegne, P; Dall'ava, D; Clement, R; Degros, J P

1995-06-01

A chemical separation method has been developed for the determination of (99)Tc in various types of radioactive wastes. Such a method includes (i) fusion with NaOH, (ii) extraction in a column containing methyltrioctylammonium chloride, (iii) extraction by solvent with N-benzoyl-N-phenylhydroxylamine and, (iv) measurement by inductively-coupled plasma mass spectrometry (ICP-MS). From the performance standpoint, the recovery of (99)Tc, using (99m)Tc as a yield tracer, is higher than 70%. This analytical method, as developed, ensures effective decontamination with respect to the radionuclides, insofar the decontamination factors are greater than 10(+5), whenever the residual activity may be measured. Taking into account a 3sigma counting error, the detection limit obtained with the ICP-MS technique is 1.9 mBq/ml; the method enabling hence to detect activities as low as 0.3 Bq/g, with analysed samples of 0.2 g and a radiochemical yield of 70%. Studies have been dedicated to the (99)Tc measurement, using the electrothermal vaporization ICP-MS technique, which lowers the detection limit by a factor 10, with the standard solution (0.3 pg/ml), compared with the previous ICP-MS technique.

Quantifying efficacy and limits of unmanned aerial vehicle (UAV) technology for weed seedling detection as affected by sensor resolution.

PubMed

Peña, José M; Torres-Sánchez, Jorge; Serrano-Pérez, Angélica; de Castro, Ana I; López-Granados, Francisca

2015-03-06

In order to optimize the application of herbicides in weed-crop systems, accurate and timely weed maps of the crop-field are required. In this context, this investigation quantified the efficacy and limitations of remote images collected with an unmanned aerial vehicle (UAV) for early detection of weed seedlings. The ability to discriminate weeds was significantly affected by the imagery spectral (type of camera), spatial (flight altitude) and temporal (the date of the study) resolutions. The colour-infrared images captured at 40 m and 50 days after sowing (date 2), when plants had 5-6 true leaves, had the highest weed detection accuracy (up to 91%). At this flight altitude, the images captured before date 2 had slightly better results than the images captured later. However, this trend changed in the visible-light images captured at 60 m and higher, which had notably better results on date 3 (57 days after sowing) because of the larger size of the weed plants. Our results showed the requirements on spectral and spatial resolutions needed to generate a suitable weed map early in the growing season, as well as the best moment for the UAV image acquisition, with the ultimate objective of applying site-specific weed management operations.

Quencher-Free Fluorescence Method for the Detection of Mercury(II) Based on Polymerase-Aided Photoinduced Electron Transfer Strategy.

PubMed

Liu, Haisheng; Ma, Linbin; Ma, Changbei; Du, Junyan; Wang, Meilan; Wang, Kemin

2016-11-18

A new quencher-free Hg 2+ ion assay method was developed based on polymerase-assisted photoinduced electron transfer (PIET). In this approach, a probe is designed with a mercury ion recognition sequence (MRS) that is composed of two T-rich functional areas separated by a spacer of random bases at the 3'-end, and a sequence of stacked cytosines at the 5'-end, to which a fluorescein (FAM) is attached. Upon addition of Hg 2+ ions into this sensing system, the MRS folds into a hairpin structure at the 3'-end with Hg 2+ -mediated base pairs. In the presence of DNA polymerase, it will catalyze the extension reaction, resulting in the formation of stacked guanines, which will instantly quench the fluorescence of FAM through PIET. Under optimal conditions, the limit of detection for Hg 2+ ions was estimated to be 5 nM which is higher than the US Environmental Protection Agency (EPA) standard limit. In addition, no labeling with a quencher was requiring, and the present method is fairly simple, fast and low cost. It is expected that this cost-effective fluorescence method might hold considerable potential in the detection of Hg 2+ ions in real biological and environmental samples.

The Condensate Database for Big Data Analysis

NASA Astrophysics Data System (ADS)

Gallaher, D. W.; Lv, Q.; Grant, G.; Campbell, G. G.; Liu, Q.

2014-12-01

Although massive amounts of cryospheric data have been and are being generated at an unprecedented rate, a vast majority of the otherwise valuable data have been ``sitting in the dark'', with very limited quality assurance or runtime access for higher-level data analytics such as anomaly detection. This has significantly hindered data-driven scientific discovery and advances in the polar research and Earth sciences community. In an effort to solve this problem we have investigated and developed innovative techniques for the construction of ``condensate database'', which is much smaller than the original data yet still captures the key characteristics (e.g., spatio-temporal norm and changes). In addition we are taking advantage of parallel databases that make use of low cost GPU processors. As a result, efficient anomaly detection and quality assurance can be achieved with in-memory data analysis or limited I/O requests. The challenges lie in the fact that cryospheric data are massive and diverse, with normal/abnomal patterns spanning a wide range of spatial and temporal scales. This project consists of investigations in three main areas: (1) adaptive neighborhood-based thresholding in both space and time; (2) compressive-domain pattern detection and change analysis; and (3) hybrid and adaptive condensation of multi-modal, multi-scale cryospheric data.

Fluorescence polarization immunoassay using IgY antibodies for detection of valnemulin in swine tissue.

PubMed

Zhang, Huiyan; Mi, Tiejun; Khan, Oleg Yu; Sheng, Yajie; Eremin, Sergei A; Beier, Ross C; Zhang, Suxia; Shen, Jianzhong; Wang, Zhanhui

2015-10-01

Immunoglobulin Y (IgY) is derived from egg yolk and has been identified as a cheap and high-yield immunoreagent. The application of IgY in immunoassays for the detection of chemical contaminants in food samples has rarely been reported. In this work, we describe a rapid and sensitive fluorescence polarization immunoassay (FPIA) for valnemulin (VAL) using IgY which was produced using a previously prepared immunogen. Three fluorophore-labeled VAL tracers were synthesized and the sensitivity of the best tracer (VAL-DTAF) in the optimized FPIA with antibody IgY100 demonstrated an IC50 value of 12 ng mL(-1) in buffer. After evaluation of several extraction procedures, acidified acetonitrile was selected to extract VAL from swine tissue. The recoveries of VAL in spiked swine tissue at three levels (50, 100, and 200 μg kg(-1)) were higher than 79% with coefficients of variation (CVs) lower than 12%. The limit of detection (LOD) of the FPIA in swine tissue was 26 μg kg(-1) and was lower than the maximum residue limit (MRL) of VAL set by the European Union. The study showed that IgY could be a good substitute for IgG when developing a high-throughput assay for chemical residues.

Reusable and Mediator-Free Cholesterol Biosensor Based on Cholesterol Oxidase Immobilized onto TGA-SAM Modified Smart Bio-Chips

PubMed Central

Rahman, Mohammed M.

2014-01-01

A reusable and mediator-free cholesterol biosensor based on cholesterol oxidase (ChOx) was fabricated based on self-assembled monolayer (SAM) of thioglycolic acid (TGA) (covalent enzyme immobilization by dropping method) using bio-chips. Cholesterol was detected with modified bio-chip (Gold/Thioglycolic-acid/Cholesterol-oxidase i.e., Au/TGA/ChOx) by reliable cyclic voltammetric (CV) technique at room conditions. The Au/TGA/ChOx modified bio-chip sensor demonstrates good linearity (1.0 nM to 1.0 mM; R = 0.9935), low-detection limit (∼0.42 nM, SNR∼3), and higher sensitivity (∼74.3 µAµM−1cm−2), lowest-small sample volume (50.0 μL), good stability, and reproducibility. To the best of our knowledge, this is the first statement with a very high sensitivity, low-detection limit, and low-sample volumes are required for cholesterol biosensor using Au/TGA/ChOx-chips assembly. The result of this facile approach was investigated for the biomedical applications for real samples at room conditions with significant assembly (Au/TGA/ChOx) towards the development of selected cholesterol biosensors, which can offer analytical access to a large group of enzymes for wide range of biomedical applications in health-care fields. PMID:24949733

Quantifying Efficacy and Limits of Unmanned Aerial Vehicle (UAV) Technology for Weed Seedling Detection as Affected by Sensor Resolution

PubMed Central

Peña, José M.; Torres-Sánchez, Jorge; Serrano-Pérez, Angélica; de Castro, Ana I.; López-Granados, Francisca

2015-01-01

In order to optimize the application of herbicides in weed-crop systems, accurate and timely weed maps of the crop-field are required. In this context, this investigation quantified the efficacy and limitations of remote images collected with an unmanned aerial vehicle (UAV) for early detection of weed seedlings. The ability to discriminate weeds was significantly affected by the imagery spectral (type of camera), spatial (flight altitude) and temporal (the date of the study) resolutions. The colour-infrared images captured at 40 m and 50 days after sowing (date 2), when plants had 5–6 true leaves, had the highest weed detection accuracy (up to 91%). At this flight altitude, the images captured before date 2 had slightly better results than the images captured later. However, this trend changed in the visible-light images captured at 60 m and higher, which had notably better results on date 3 (57 days after sowing) because of the larger size of the weed plants. Our results showed the requirements on spectral and spatial resolutions needed to generate a suitable weed map early in the growing season, as well as the best moment for the UAV image acquisition, with the ultimate objective of applying site-specific weed management operations. PMID:25756867

Four-year surveillance for ochratoxin a and fumonisins in retail foods in Japan.

PubMed

Aoyama, Koji; Nakajima, Masahiro; Tabata, Setsuko; Ishikuro, Eiichi; Tanaka, Toshitsugu; Norizuki, Hiroko; Itoh, Yoshinori; Fujita, Kazuhiro; Kai, Shigemi; Tsutsumi, Toru; Takahashi, Masanori; Tanaka, Hiroki; Iizuka, Seiichiro; Ogiso, Motoki; Maeda, Mamoru; Yamaguchi, Shigeaki; Sugiyama, Kei-Ichi; Sugita-Konishi, Yoshiko; Kumagai, Susumu

2010-02-01

Between 2004 and 2007 we examined foods from Japanese retail shops for contamination with ochratoxin A (OTA) and fumonisins B(1), B(2), and B(3). A total of 1,358 samples of 27 different products were examined for OTA, and 831 samples of 16 different products were examined for fumonisins. The limits of quantification ranged from 0.01 to 0.5 microg/kg for OTA and 2 to 10 microg/kg for the fumonisins. OTA was detected in amounts higher than limits of quantification in wheat flour, pasta, oatmeal, rye, buckwheat flour and dried buckwheat noodles, raisins, wine, beer, coffee beans and coffee products, chocolate, cocoa, and coriander. OTA was found in more than 90% of the samples of instant coffee and cocoa, and the highest concentration of OTA, 12.5 microg/kg, was detected in raisins. The concentration of OTA in oatmeal, rye, raisins, wine, and roasted coffee beans varied remarkably from year to year. Fumonisins were detected in frozen and canned corn, popcorn grain, corn grits, cornflakes, corn soups, corn snacks, beer, soybeans, millet, and asparagus. The highest concentrations of fumonisins B(1), B(2), and B(3) were detected in corn grits (1,670, 597, and 281 microg/kg, respectively). All of the samples of corn grits were contaminated with fumonisins, and more than 80% of the samples of popcorn grain and corn snacks contained fumonisins. OTA and fumonisins were detected in several food products in Japan; however, although Japan has not set regulatory levels for these mycotoxins, their concentrations were relatively low.

Desorption of micropollutant from spent carbon filters used for water purifier.

PubMed

Kwon, Da-Sol; Tak, So-Yeon; Lee, Jung-Eun; Kim, Moon-Kyung; Lee, Young Hwa; Han, Doo Won; Kang, Sanghyeon; Zoh, Kyung-Duk

2017-07-01

In this study, to examine the accumulated micropollutants in the spent carbon filter used in the water purifier, first, the method to desorb micropollutant from the activated carbon was developed and optimized. Then, using this optimized desorption conditions, we examined which micropollutants exist in spent carbon filters collected from houses in different regions in Korea where water purifiers were used. A total of 11 micropollutants (caffeine (CFF), acetaminophen (ACT), sulfamethazine (SMA), sulfamethoxazole (SMZ), metoprolol (MTP), carbamazepine (CBM), naproxen (NPX), bisphenol-A (BPA), ibuprofen (IBU), diclofenac (DCF), and triclocarban (TCB)) were analyzed using LC/MS-MS from the spent carbon filters. CFF, NPX, and DCF had the highest detection frequencies (>60%) in the carbon filters (n = 100), whereas SMA, SMZ, and MTP were only detected in the carbon filters, but not in the tap waters (n = 25), indicating that these micropollutants, which exist less than the detection limit in tap water, were accumulated in the carbon filters. The regional micropollutant detection patterns in the carbon filters showed higher levels of micropollutants, especially NPX, BPA, IBU, and DCF, in carbon filters collected in the Han River and Nakdong River basins where large cities exist. The levels of micropollutants in the carbon filter were generally lower in the regions where advanced oxidation processes (AOPs) were employed at nearby water treatment plants (WTPs), indicating that AOP process in WTP is quite effective in removing micropollutant. Our results suggest that desorption of micropollutant from the carbon filter used can be a tool to identify micropollutants present in tap water with trace amounts or below the detection limit.

A method of analysis for T-2 toxin and neosolaniol by UPLC-MS/MS in apple fruit inoculated with Trichothecium roseum.

PubMed

Tang, Yamei; Xue, Huali; Bi, Yang; Li, Yongcai; Wang, Yi; Zhao, Ying; Shen, Keping

2015-01-01

Trichothecenes are one of the most important groups of mycotoxins produced by Trichothecium roseum, which causes core rot of apple. A reliable and sensitive method was developed and successfully applied for the rapid detection of trichothecenes including T-2 toxin and neosolaniol in harvested apple using UPLC-MS/MS. After the extraction of the two mycotoxins from the apple matrix with methanol/water (80/20, v/v), the concentrated extracts were cleaned-up by PriboFast M270 columns and then analysed by UPLC-MS/MS. T-2 toxin and neosolaniol were effectively separated as unique peaks. The validity of this method was established by its linearity (R(2) ≥ 0.9995), precision (relative standard deviation ≤ 3.6%), accuracy, selectivity, limit of detection of 2-5 μg kg(-1), limit of quantification of 5-10 μg kg(-1) and average recovery of 73-96%. Levels of T-2 toxin were found in the range 7.1-128.4 µg kg(-1) in the core rot lesion of three cultivars apple (cvs. Red Delicious, Fuji and Ralls). T-2 was detected not only in the lesion, but also in the tissue without any disease symptoms. However, neosolaniol was only detected in the lesion on 'Red Delicious' apples. In addition, the concentration of T-2 toxin in the susceptible cultivar (cv. Fuji) was significantly higher than that in the resistant one (cv. Ralls). This method proved to be suitable at detecting T-2 and neosolaniol simultaneously in apples infected with T. roseum.

Analysis of chemical warfare agents in food products by atmospheric pressure ionization-high field asymmetric waveform ion mobility spectrometry-mass spectrometry.

PubMed

Kolakowski, Beata M; D'Agostino, Paul A; Chenier, Claude; Mester, Zoltán

2007-11-01

Flow injection high field asymmetric waveform ion mobility spectrometry (FAIMS)-mass spectrometry (MS) methodology was developed for the detection and identification of chemical warfare (CW) agents in spiked food products. The CW agents, soman (GD), sarin (GB), tabun (GA), cyclohexyl sarin (GF), and four hydrolysis products, ethylphosphonic acid (EPA), methylphosphonic acid (MPA), pinacolyl methylphosphonic acid (Pin MPA), and isopropyl methylphosphonic acid (IMPA) were separated and detected by positive ion and negative ion atmospheric pressure ionization-FAIMS-MS. Under optimized conditions, the compensation voltages were 7.2 V for GD, 8.0 V for GA, 7.2 V for GF, 7.6 V for GB, 18.2 V for EPA, 25.9 V for MPA, -1.9 V for PinMPA, and +6.8 V for IMPA. Sample preparation was kept to a minimum, resulting in analysis times of 3 min or less per sample. The developed methodology was evaluated by spiking bottled water, canola oil, cornmeal, and honey samples at low microgram per gram (or microg/mL) levels with the CW agents or CW agent hydrolysis products. The detection limits observed for the CW agents in the spiked food samples ranged from 3 to 15 ng/mL in bottled water, 1-33 ng/mL in canola oil, 1-34 ng/g in cornmeal, and 13-18 ng/g in honey. Detection limits were much higher for the CW agent hydrolysis products, with only MPA being detected in spiked honey samples.

Association of lipoarabinomannan with high density lipoprotein in blood: Implications for diagnostics

DOE PAGES

Sakamuri, Rama Murthy; Price, Dominique N.; Lee, Myungsun; ...

2013-02-14

Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We also applied an ultra-sensitive detection strategy developed for amphiphilic biomarkers, membrane insertion, to the detection of LAM with a limit of detection of 10 fM. Herein, we evaluate the application of membrane insertion to the detection of LAM in patient serum,more » and demonstrate that the circulating concentrations of ‘monomeric’ LAM in serum are very low, despite significantly higher concentrations in the urine. Using spiked samples, we demonstrate that this discrepancy is due to the association of LAM with high-density lipoprotein (HDL) nanodiscs in human serum. Indeed, pull-down of HDL nanodiscs from human serum allows for the recovery of HDL-associated LAM. These studies suggest that LAM is likely associated with carrier molecules such as HDL in the blood of patients infected with tuberculosis. Furthermore, this phenomenon may not be limited to LAM in that many pathogen-associated molecular patterns like LAM are amphiphilic in nature and may also be associated with host lipid carriers. Such interactions are likely to affect host–pathogen interactions, pathogen bio-distribution and clearance in the host, and must be thoroughly understood for the effective design of vaccines and diagnostics.« less

Association of lipoarabinomannan with high density lipoprotein in blood: Implications for diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakamuri, Rama Murthy; Price, Dominique N.; Lee, Myungsun

Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We also applied an ultra-sensitive detection strategy developed for amphiphilic biomarkers, membrane insertion, to the detection of LAM with a limit of detection of 10 fM. Herein, we evaluate the application of membrane insertion to the detection of LAM in patient serum,more » and demonstrate that the circulating concentrations of ‘monomeric’ LAM in serum are very low, despite significantly higher concentrations in the urine. Using spiked samples, we demonstrate that this discrepancy is due to the association of LAM with high-density lipoprotein (HDL) nanodiscs in human serum. Indeed, pull-down of HDL nanodiscs from human serum allows for the recovery of HDL-associated LAM. These studies suggest that LAM is likely associated with carrier molecules such as HDL in the blood of patients infected with tuberculosis. Furthermore, this phenomenon may not be limited to LAM in that many pathogen-associated molecular patterns like LAM are amphiphilic in nature and may also be associated with host lipid carriers. Such interactions are likely to affect host–pathogen interactions, pathogen bio-distribution and clearance in the host, and must be thoroughly understood for the effective design of vaccines and diagnostics.« less

A ratiometric strategy -based electrochemical sensing interface for the sensitive and reliable detection of imidacloprid.

PubMed

Li, Xueyan; Kan, Xianwen

2018-04-30

In this study, a ratiometric strategy-based electrochemical sensor was developed by electropolymerization of thionine (THI) and β-cyclodextrin (β-CD) composite films on a glassy carbon electrode surface for imidacloprid (IMI) detection. THI played the role of an inner reference element to provide a built-in correction. In addition, the modified β-CD showed good selective enrichment for IMI to improve the sensitivity and anti-interference ability of the sensor. The current ratio between IMI and THI was calculated as the detected signal for IMI sensing. Compared with common single-signal sensing, the proposed ratiometric strategy showed a higher linear range and a lower limit of detection of 4.0 × 10-8-1.0 × 10-5 mol L-1 and 1.7 × 10-8 mol L-1, respectively, for IMI detection. On the other hand, the ratiometric strategy endowed the sensor with good accuracy, reproducibility, and stability. The sensor was also used for IMI determination in real samples with satisfactory results. The simple, effective, and reliable way reported in this study can be further used to prepare ratiometric strategy-based electrochemical sensors for the selective and sensitive detection of other compounds with good accuracy and stability.

Detection of highly toxic elements (lead and chromium) in commercially available eyeliner (kohl) using laser induced break down spectroscopy

NASA Astrophysics Data System (ADS)

Gondal, M. A.; Dastageer, M. A.; Al-Adel, F. F.; Naqvi, A. A.; Habibullah, Y. B.

2015-12-01

A sensitive laser induced breakdown spectroscopic system was developed and optimized for using it as a sensor for the detection of trace levels of lead and chromium present in the cosmetic eyeliner (kohl) of different price ranges (brands) available in the local market. Kohl is widely used in developing countries for babies as well adults for beautification as well eyes protection. The atomic transition lines at 405.7 nm and 425.4 nm were used as the marker lines for the detection of lead and chromium respectively. The detection system was optimized by finding the appropriate gate delay between the laser excitation and the data acquisition system and also by achieving optically thin plasma near the target by establishing the local thermodynamic equilibrium condition. The detection system was calibrated for these two hazardous elements and the kohl samples under investigation showed 8-15 ppm by mass of lead and 4-9 ppm by mass of Chromium, which are higher than the safe permissible levels of these elements. The limits of detection of the LIBS system for lead and chromium were found to be 1 and 2 ppm respectively.

Matrix-Matching as an Improvement Strategy for the Detection of Pesticide Residues.

PubMed

Giacinti, Géraldine; Raynaud, Christine; Capblancq, Sophie; Simon, Valérie

2016-05-01

More than 90% of the pesticides residues in apples are located in the peel. We developed a gas chromatography/ion trap tandem mass spectrometry method for investigating all detectable residues in the peel of 3 apple varieties. Sample preparation is based on the use of the Quick Easy Cheap Effective Rugged and Safe method on the whole fruit, the flesh, and the peel. Pesticide residues were quantified with solvent-matched and matrix-matched standards, by spiking apple sample extracts. Matrix effects dependent on the type of extract (fruit, flesh, or peel) and the apple variety were detected. The best data processing methods involved normalizing matrix effect rates by matrix-matched internal/external calibration. Boscalid, captan, chlorpyrifos, fludioxonil, and pyraclostrobin were the most frequently detected pesticides. However, their concentrations in the whole fruit were below European maximum residue levels. Despite negative matrix effects, the residues in peel were detected at concentrations up to 10 times higher than those in whole fruits. Consequently, other pesticide residues present at concentrations below the limit of quantification in the whole fruit were detected in the peel. © 2016 Institute of Food Technologists®

A statistical approach to detection of copy number variations in PCR-enriched targeted sequencing data.

PubMed

Demidov, German; Simakova, Tamara; Vnuchkova, Julia; Bragin, Anton

2016-10-22

Multiplex polymerase chain reaction (PCR) is a common enrichment technique for targeted massive parallel sequencing (MPS) protocols. MPS is widely used in biomedical research and clinical diagnostics as the fast and accurate tool for the detection of short genetic variations. However, identification of larger variations such as structure variants and copy number variations (CNV) is still being a challenge for targeted MPS. Some approaches and tools for structural variants detection were proposed, but they have limitations and often require datasets of certain type, size and expected number of amplicons affected by CNVs. In the paper, we describe novel algorithm for high-resolution germinal CNV detection in the PCR-enriched targeted sequencing data and present accompanying tool. We have developed a machine learning algorithm for the detection of large duplications and deletions in the targeted sequencing data generated with PCR-based enrichment step. We have performed verification studies and established the algorithm's sensitivity and specificity. We have compared developed tool with other available methods applicable for the described data and revealed its higher performance. We showed that our method has high specificity and sensitivity for high-resolution copy number detection in targeted sequencing data using large cohort of samples.

Detection limits of intraoperative near infrared imaging for tumor resection.

PubMed

Thurber, Greg M; Figueiredo, Jose-Luiz; Weissleder, Ralph

2010-12-01

The application of fluorescent molecular imaging to surgical oncology is a developing field with the potential to reduce morbidity and mortality. However, the detection thresholds and other requirements for successful intervention remain poorly understood. Here we modeled and experimentally validated depth and size of detection of tumor deposits, trade-offs in coverage and resolution of areas of interest, and required pharmacokinetics of probes based on differing levels of tumor target presentation. Three orthotopic tumor models were imaged by widefield epifluorescence and confocal microscopes, and the experimental results were compared with pharmacokinetic models and light scattering simulations to determine detection thresholds. Widefield epifluorescence imaging can provide sufficient contrast to visualize tumor margins and detect tumor deposits 3-5  mm deep based on labeled monoclonal antibodies at low objective magnification. At higher magnification, surface tumor deposits at cellular resolution are detectable at TBR ratios achieved with highly expressed antigens. A widefield illumination system with the capability for macroscopic surveying and microscopic imaging provides the greatest utility for varying surgical goals. These results have implications for system and agent designs, which ultimately should aid complete resection in most surgical beds and provide real-time feedback to obtain clean margins. © 2010 Wiley-Liss, Inc.

Detection of dechallenge in spontaneous reporting systems: a comparison of Bayes methods.

PubMed

Banu, A Bazila; Alias Balamurugan, S Appavu; Thirumalaikolundusubramanian, Ponniah

2014-01-01

Dechallenge is a response observed for the reduction or disappearance of adverse drug reactions (ADR) on withdrawal of a drug from a patient. Currently available algorithms to detect dechallenge have limitations. Hence, there is a need to compare available new methods. To detect dechallenge in Spontaneous Reporting Systems, data-mining algorithms like Naive Bayes and Improved Naive Bayes were applied for comparing the performance of the algorithms in terms of accuracy and error. Analyzing the factors of dechallenge like outcome and disease category will help medical practitioners and pharmaceutical industries to determine the reasons for dechallenge in order to take essential steps toward drug safety. Adverse drug reactions of the year 2011 and 2012 were downloaded from the United States Food and Drug Administration's database. The outcome of classification algorithms showed that Improved Naive Bayes algorithm outperformed Naive Bayes with accuracy of 90.11% and error of 9.8% in detecting the dechallenge. Detecting dechallenge for unknown samples are essential for proper prescription. To overcome the issues exposed by Naive Bayes algorithm, Improved Naive Bayes algorithm can be used to detect dechallenge in terms of higher accuracy and minimal error.

Oil Spill AISA+ Hyperspectral Data Detection Based on Different Sea Surface Glint Suppression Methods

NASA Astrophysics Data System (ADS)

Yang, J.; Ren, G.; Ma, Y.; Dong, L.; Wan, J.

2018-04-01

The marine oil spill is a sudden event, and the airborne hyperspectral means to detect the oil spill is an important part of the rapid response. Sun glint, the specular reflection of sun light from water surface to sensor, is inevitable due to the limitation of observation geometry, which makes so much bright glint in image that it is difficult to extract oil spill feature information from the remote sensing data. This paper takes AISA+ airborne hyperspectral oil spill image as data source, using multi-scale wavelet transform, enhanced Lee filter, enhanced Frost filter and mean filter method for sea surface glint suppression of images. And then the classical SVM method is used for the oil spill information detection, and oil spill information distribution map obtained by human-computer interactive interpretation is used to verify the accuracy of oil spill detection. The results show that the above methods can effectively suppress the sea surface glints and improve the accuracy of oil spill detection. The enhanced Lee filter method has the highest detection accuracy of 88.28 %, which is 12.2 % higher than that of the original image.

Surface-Enhanced Raman Scattering-Based Immunoassay Technologies for Detection of Disease Biomarkers

PubMed Central

Smolsky, Joseph; Kaur, Sukhwinder; Hayashi, Chihiro; Batra, Surinder K.; Krasnoslobodtsev, Alexey V.

2017-01-01

Detection of biomarkers is of vital importance in disease detection, management, and monitoring of therapeutic efficacy. Extensive efforts have been devoted to the development of novel diagnostic methods that detect and quantify biomarkers with higher sensitivity and reliability, contributing to better disease diagnosis and prognosis. When it comes to such devastating diseases as cancer, these novel powerful methods allow for disease staging as well as detection of cancer at very early stages. Over the past decade, there have been some advances in the development of platforms for biomarker detection of diseases. The main focus has recently shifted to the development of simple and reliable diagnostic tests that are inexpensive, accurate, and can follow a patient’s disease progression and therapy response. The individualized approach in biomarker detection has been also emphasized with detection of multiple biomarkers in body fluids such as blood and urine. This review article covers the developments in Surface-Enhanced Raman Scattering (SERS) and related technologies with the primary focus on immunoassays. Limitations and advantages of the SERS-based immunoassay platform are discussed. The article thoroughly describes all components of the SERS immunoassay and highlights the superior capabilities of SERS readout strategy such as high sensitivity and simultaneous detection of a multitude of biomarkers. Finally, it introduces recently developed strategies for in vivo biomarker detection using SERS. PMID:28085088

Role of Magnetic Resonance Imaging in Prostate Cancer Screening: A Pilot Study Within the Göteborg Randomised Screening Trial

PubMed Central

Bergdahl, Anna Grenabo; Wilderäng, Ulrica; Aus, Gunnar; Carlsson, Sigrid; Damber, Jan-Erik; Frånlund, Maria; Geterud, Kjell; Khatami, Ali; Socratous, Andreas; Stranne, Johan; Hellström, Mikael; Hugosson, Jonas

2016-01-01

Background Magnetic resonance imaging (MRI) and targeted biopsies (TB) have shown potential to more accurately detect significant prostate cancer (PC) compared to prostate-specific antigen (PSA) and systematic biopsies (SB). Objective To compare sequential screening (PSA + MRI) with conventional PSA screening. Design, Setting and Participants Of 384 attendees in the 10th screening round of the Göteborg randomised screening trial, 124 men, median age 69.5, had a PSA of ≥1.8 ng/ml and underwent a prebiopsy MRI. Men with suspicious lesions on MRI and/or PSA ≥3.0 ng/ml were referred for biopsy. SB was performed blinded to MRI results and TB was performed in men with tumour-suspicious findings on MRI. Three screening strategies were compared (PSA≥3.0+SB; PSA≥3.0+MRI+TB and PSA≥1.8+MRI+TB). Outcome Measurements and Statistical Analysis Cancer detection rates, sensitivity and specificity were calculated per screening strategy and compared using McNemar´s test. Results and Limitations In total, 28 PC were detected, of which 20 were diagnosed in biopsy-naïve men. Both PSA≥3.0+MRI and PSA≥1.8+MRI significantly increased specificity compared with PSA≥3.0+SB (0.92 and 0.79 vs. 0.52; p<0.002 for both), while sensitivity was significantly higher for PSA≥1.8+MRI compared with PSA>=3.0+MRI (0.73 vs. 0.46, p=0.008). The detection rate of significant cancer was higher with PSA≥1.8+MRI compared to PSA≥3.0+SB (5.9 vs. 4.0%), while the detection rate of insignificant cancer was lowered by PSA≥3.0+MRI (0.3 vs. 1.2%). The primary limitation of this study is the small sample of men. Conclusion A screening strategy with a lowered PSA cut-off followed by TB in MRI-positive men seems to increase the detection of significant cancers while improving specificity. If replicated, these results may contribute to a paradigm shift in future screening. Patient Summary Major concerns in prostate-specific antigen screening are overdiagnosis and underdiagnosis. We evaluated whether prostate magnetic resonance imaging could improve the balance of benefits to harm in prostate cancer screening, and we found promising potential of using magnetic resonance imaging in addition to prostate-specific antigen. PMID:26724840

Occurrence, distribution, and dechlorination of polychlorinated biphenyls and health risk assessment in Selangor River basin.

PubMed

Sakai, Nobumitsu; Dayana, Emmy; Abu Bakar, Azizi; Yoneda, Minoru; Nik Sulaiman, Nik Meriam; Ali Mohd, Mustafa

2016-10-01

Polychlorinated biphenyls (PCBs) were monitored in surface water collected in the Selangor River basin, Malaysia, to identify the occurrence, distribution, and dechlorination process as well as to assess the potential adverse effects to the Malaysian population. Ten PCB homologs (i.e., mono-CBs to deca-CBs) were quantitated by using gas chromatography-mass spectrometry (GC/MS). The total concentration of PCBs in the 10 sampling sites ranged from limit of detection to 7.67 ng L -1 . The higher chlorinated biphenyls (tetra-CBs to deca-CBs) were almost not detected in most of the sampling sites, whereas lower chlorinated biphenyls (mono-CBs, di-CBs, and tri-CBs) dominated more than 90 % of the 10 homologs in all the sampling sites. Therefore, the PCB load was estimated to be negligible during the sampling period because PCBs have an extremely long half-life. The PCBs, particularly higher chlorinated biphenyls, could be thoroughly dechlorinated to mono-CBs to tri-CBs by microbial decomposition in sediment or could still be accumulated in the sediment. The lower chlorinated biphenyls, however, could be resuspended or desorbed from the sediment because they have faster desorption rates and higher solubility, compared to the higher chlorinated biphenyls. The health risk for the Malaysia population by PCB intake that was estimated from the local fish consumption (7.2 ng kg -1 bw day -1 ) and tap water consumption (1.5 × 10 -3 -3.1 × 10 -3  ng kg -1 bw day -1 ) based on the detected PCB levels in the surface water was considered to be minimal. The hazard quotient based on the tolerable daily intake (20 ng kg -1 bw day -1 ) was estimated at 0.36.

Biosensor technology for pesticides--a review.

PubMed

Verma, Neelam; Bhardwaj, Atul

2015-03-01

Pesticides, due to their lucrative outcomes, are majorly implicated in agricultural fields for crop production enhancement. Due to their pest removal properties, pesticides of various classes have been designed to persist in the environment over a longer duration after their application to achieve maximum effectiveness. Apart from their recalcitrant structure and agricultural benefits, pesticides also impose acute toxicological effects onto the other various life forms. Their accumulation in the living system may prove to be detrimental if established in higher concentrations. Thus, their prompt and accurate analysis is a crucial matter of concern. Conventional techniques like chromatographic techniques (HPLC, GC, etc.) used for pesticides detection are associated with various limitations like stumpy sensitivity and efficiency, time consumption, laboriousity, requirement of expensive equipments and highly trained technicians, and many more. So there is a need to recruit the methods which can detect these neurotoxic compounds sensitively, selectively, rapidly, and easily in the field. Present work is a brief review of the pesticide effects, their current usage scenario, permissible limits in various food stuffs and 21st century advancements of biosensor technology for pesticide detection. Due to their exceptional performance capabilities, easiness in operation and on-site working, numerous biosensors have been developed for bio-monitoring of various environmental samples for pesticide evaluation immensely throughout the globe. Till date, based on sensing element (enzyme based, antibody based, etc.) and type of detection method used (Electrochemical, optical, and piezoelectric, etc.), a number of biosensors have been developed for pesticide detection. In present communication, authors have summarized 21st century's approaches of biosensor technology for pesticide detection such as enzyme-based biosensors, immunosensors, aptamers, molecularly imprinted polymers, and biochips technology. Also, the major technological advancements of nanotechnology in the field of biosensor technology are discussed. Various biosensors mentioned in manuscript are found to exhibit storage stability of biocomponent ranging from 30-60 days, detection limit of 10(-6) - 10(-16) M, response time of 1-20 min and applications of developed biosensors in environmental samples (water, food, vegetables, milk, and juice samples, etc.) are also discussed. Researchers all over the globe are working towards the development of different biosensing techniques based on contrast approaches for the detection of pesticides in various environmental samples.

Direct Quantification of Post-Stress-Rest Left Ventricular Motion and Thickening Changes for Myocardial Perfusion SPECT

PubMed Central

Karimi-Ashtiani, Shahryar; Arsanjani, Reza; Fish, Mathews; Kavanagh, Paul; Germano, Guido; Berman, Daniel; Slomka, Piotr

2012-01-01

Changes in myocardial wall motion and thickening during myocardial perfusion single-photon emission computed tomography (MPS) are typically assessed separately from gated studies to assess for stress induced functional abnormalities. We sought to develop and validate a novel approach for automatic quantification of post-stress-rest myocardial motion and thickening changes (MTC). Methods Endocardial surfaces at the end-diastolic and end-systolic frames for post-stress and rest studies were registered automatically to each other by matching ventricular surfaces. Myocardial MTCs were computed and normal limits of change were determined as the mean and standard deviation for each polar sample. Normal limits were utilized to quantify the MTCs for each map and the accumulated sample values were used for abnormality assessments in segmental regions. A hybrid method was devised by combining the Total Perfusion Deficit (TPD) and MTC for each vessel territory. Normal limits were obtained from 100 subjects with low likelihood (LLK) of coronary artery disease (CAD). For validation, 623 subjects with correlating invasive angiography were studied. All subjects had a stress/rest 99mTc-sestamibi exercise or adenosine test, and all had coronary angiography within 3 months of MPS. All MTC and TPD measurements were derived automatically. The diagnostic accuracy for detection of coronary artery disease for MTC+TPD was compared to TPD alone. Results Segmental normal values for motion change were between −1.3 and −4.1 mm and between −30.1% and −9.8% for thickening change. MTC combined with TPD achieved 61% sensitivity for 3-vessel disease (3VD), 63% for 2-vessel disease (2VD), and 90% for 1-vessel disease (1VD) detection vs. 32% for 3VD (P <0.0001), 53% for 2VD (P < 0.001), and 90% for 1VD (P = 1.0) detection with TPD alone method. The specificity for the combined method was 71% for 3VD, 72% for 2VD, and 47% for 1 VD detection vs. 90% for 3VD (P < 0.0001), 80% for 2VD (P <0.001), and 50% for 1VD detection (P=0.0625) for TPD alone method. The accuracy of 3VD detection by MTC+TPD was higher (69%) than the accuracy of TPD + change in ejection fraction (63%), (P< 0.004). Conclusion We established normal limits and a novel method for computation of regional functional changes between post-stress and rest. Combination of (TPD) with MTC improved the sensitivity for the detection of 3VD and 2VD as compared to TPD alone. PMID:22872739

Lactoferrin Isolation Using Monolithic Column Coupled with Spectrometric or Micro-Amperometric Detector

PubMed Central

Adam, Vojtech; Zitka, Ondrej; Dolezal, Petr; Zeman, Ladislav; Horna, Ales; Hubalek, Jaromir; Sileny, Jan; Krizkova, Sona; Trnkova, Libuse; Kizek, Rene

2008-01-01

Lactoferrin is a multifunctional protein with antimicrobial activity and others to health beneficial properties. The main aim of this work was to propose easy to use technique for lactoferrin isolation from cow colostrum samples. Primarily we utilized sodium dodecyl sulphate – polyacrylamide gel electrophoresis for isolation of lactoferrin from the real samples. Moreover we tested automated microfluidic Experion electrophoresis system to isolate lactoferrin from the collostrum sample. The well developed signal of lactoferrin was determined with detection limit (3 S/N) of 20 ng/ml. In spite of the fact that Experion is faster than SDS-PAGE both separation techniques cannot be used in routine analysis. Therefore we have tested third separation technique, ion exchange chromatography, using monolithic column coupled with UV-VIS detector (LC-UV-VIS). We optimized wave length (280 nm), ionic strength of the elution solution (1.5 M NaCl) and flow rate of the retention and elution solutions (0.25 ml/min and 0.75 ml/min. respectively). Under the optimal conditions the detection limit was estimated as 0.1 μg/ml of lactoferrin measured. Using LC-UV-VIS we determined that lactoferrin concentration varied from 0.5 g/l to 1.1 g/l in cow colostrums collected in the certain time interval up to 72 hours after birth. Further we focused on miniaturization of detection device. We tested amperometric detection at carbon electrode. The results encouraged us to attempt to miniaturise whole detection system and to test it on analysis of real samples of human faeces, because lactoferrin level in faeces is closely associated with the inflammations of intestine mucous membrane. For the purpose of miniaturization we employed the technology of printed electrodes. The detection limit of lactoferrin was estimated as 10 μg/ml measured by the screen-printed electrodes fabricated by us. The fabricated electrodes were compared with commercially available ones. It follows from the obtained results that the responses measured by commercial electrodes are app. ten times higher compared with those measured by the electrodes fabricated by us. This phenomenon relates with smaller working electrode surface area of the electrodes fabricated by us (about 50 %) compared to the commercial ones. The screen-printed electrodes fabricated by us were utilized for determination of lactoferrin faeces. Regarding to fact that sample of faeces was obtained from young and healthy man the amount of lactoferrin in sample was under the limit of detection of this method. PMID:27879717

Screening method for the determination of tetracyclines and fluoroquinolones in animal drinking water by liquid chromatography with diode array detector.

PubMed

Patyra, E; Kowalczyk, E; Grelik, A; Przeniosło-Siwczyńska, M; Kwiatek, K

2015-01-01

A liquid chromatography - diode array detector (HPLC-DAD) procedure has been developed for the determination of oxytetracycline (OTC), tetracycline (TC), chlorotetracycline (CTC), doxycycline (DC), enrofloxacin (ENR), ciprofloxacin (CIP), sarafloxacin (SAR) and flumequine (FLU) residues in animal drinking water. This method was applied to animal drinking water. Solid-phase extraction (SPE) clean-up on an Oasis HLB cartridge allowed an extract suitable for liquid chromatographic analysis to be obtained. Chromatographic separation was carried out on a C18 analytical column, using gradient elution with 0.1% trifluoroacetic acid - acetonitrile - methanol at 30°C. The flow-rate was 0.7 mL/min and the eluate was analysed at 330 nm. The whole procedure was evaluated according to the requirements of the Commission Decision 2002/657/EC, determining specificity, decision limit (CCα), detection capacity (CCβ), limit of detection (LOD), limit of quantification (LOQ), precision and accuracy during validation of the method. The recoveries of TCs and FQs from spiked samples at the levels of 10, 100 and 1000 μg/L were higher than 82%. The developed method based on HPLC-DAD has been applied for the determination of four tetracyclines and four fluoroquinolones in animal drinking water samples.

Conjunctions between motion and disparity are encoded with the same spatial resolution as disparity alone.

PubMed

Allenmark, Fredrik; Read, Jenny C A

2012-10-10

Neurons in cortical area MT respond well to transparent streaming motion in distinct depth planes, such as caused by observer self-motion, but do not contain subregions excited by opposite directions of motion. We therefore predicted that spatial resolution for transparent motion/disparity conjunctions would be limited by the size of MT receptive fields, just as spatial resolution for disparity is limited by the much smaller receptive fields found in primary visual cortex, V1. We measured this using a novel "joint motion/disparity grating," on which human observers detected motion/disparity conjunctions in transparent random-dot patterns containing dots streaming in opposite directions on two depth planes. Surprisingly, observers showed the same spatial resolution for these as for pure disparity gratings. We estimate the limiting receptive field diameter at 11 arcmin, similar to V1 and much smaller than MT. Higher internal noise for detecting joint motion/disparity produces a slightly lower high-frequency cutoff of 2.5 cycles per degree (cpd) versus 3.3 cpd for disparity. This suggests that information on motion/disparity conjunctions is available in the population activity of V1 and that this information can be decoded for perception even when it is invisible to neurons in MT.

Effectiveness of medicines authentication technology to detect counterfeit, recalled and expired medicines: a two-stage quantitative secondary care study

PubMed Central

Naughton, Bernard; Roberts, Lindsey; Dopson, Sue; Chapman, Stephen; Brindley, David

2016-01-01

Objectives To identify the authentication and detection rate of serialised medicines using medicines authentication technology. Design and intervention 4192 serialised medicines were entered into a hospital dispensary over two separate 8-week stages in 2015. Medicines were authenticated using secure external database cross-checking, triggered by the scanning of a two-dimensional data matrix with a unit specific 12-digit serial code. 4% of medicines included were preprogrammed with a message to identify the product as either expired, pack recalled, product recalled or counterfeit. Setting A site within a large UK National Health Service teaching hospital trust. Participants Accredited checking staff, pharmacists and dispensers in a pharmacy department. Primary outcome measures Authentication and detection rate of counterfeit expired and recalled medicines. Results The operational detection rate of counterfeit, recalled and expired medicines scanned as a combined group was 81.4% (stage 1 (S1)) and 87% (stage 2 (S2)). The technology's technical detection rate (TDR) was 100%; however, not all medicines were scanned and of those that were scanned not all that generated a warning message were quarantined. Owing to an operational authentication rate (OAR) of 66.3% (over both stages), only 31.8% of counterfeit medicines, 58% of recalled drugs and 64% of expired medicines were detected as a proportion of those entered into the study. Response times (RTs) of 152 ms (S1) and 165 ms (S2) were recorded, meeting the falsified medicines directive-mandated 300 ms limit. Conclusions TDRs and RTs were not a limiting factor in this study. The suboptimal OAR poses significant quality and safety issues with this detection approach. Authentication at the checking stage, however, demonstrated higher OARs. There is a need for further qualitative research to establish the reasons for less than absolute authentication and detection rates in the hospital environment to improve this technology in preparation for the incumbent European Union regulative deadline. PMID:27940634

Lesion detection performance: comparative analysis of low-dose CT data of the chest on two hybrid imaging systems.

PubMed

Jessop, Maryam; Thompson, John D; Coward, Joanne; Sanderud, Audun; Jorge, José; de Groot, Martijn; Lança, Luís; Hogg, Peter

2015-03-01

Incidental findings on low-dose CT images obtained during hybrid imaging are an increasing phenomenon as CT technology advances. Understanding the diagnostic value of incidental findings along with the technical limitations is important when reporting image results and recommending follow-up, which may result in an additional radiation dose from further diagnostic imaging and an increase in patient anxiety. This study assessed lesions incidentally detected on CT images acquired for attenuation correction on two SPECT/CT systems. An anthropomorphic chest phantom containing simulated lesions of varying size and density was imaged on an Infinia Hawkeye 4 and a Symbia T6 using the low-dose CT settings applied for attenuation correction acquisitions in myocardial perfusion imaging. Twenty-two interpreters assessed 46 images from each SPECT/CT system (15 normal images and 31 abnormal images; 41 lesions). Data were evaluated using a jackknife alternative free-response receiver-operating-characteristic analysis (JAFROC). JAFROC analysis showed a significant difference (P < 0.0001) in lesion detection, with the figures of merit being 0.599 (95% confidence interval, 0.568, 0.631) and 0.810 (95% confidence interval, 0.781, 0.839) for the Infinia Hawkeye 4 and Symbia T6, respectively. Lesion detection on the Infinia Hawkeye 4 was generally limited to larger, higher-density lesions. The Symbia T6 allowed improved detection rates for midsized lesions and some lower-density lesions. However, interpreters struggled to detect small (5 mm) lesions on both image sets, irrespective of density. Lesion detection is more reliable on low-dose CT images from the Symbia T6 than from the Infinia Hawkeye 4. This phantom-based study gives an indication of potential lesion detection in the clinical context as shown by two commonly used SPECT/CT systems, which may assist the clinician in determining whether further diagnostic imaging is justified. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Detection of total and A1c-glycosylated hemoglobin in human whole blood using sandwich immunoassays on polydimethylsiloxane-based antibody microarrays.

PubMed

Chen, Huang-Han; Wu, Chih-Hsing; Tsai, Mei-Ling; Huang, Yi-Jing; Chen, Shu-Hui

2012-10-16

The percentage of glycosylated hemoglobin A1c (%GHbA1c) in human whole blood indicates the average plasma glucose concentration over a prolonged period of time and is used to diagnose diabetes. However, detecting GHbA1c in the whole blood using immunoassays has limited detection sensitivity due to its low percentage in total hemoglobin (tHb) and interference from various glycan moieties in the sample. We have developed a sandwich immunoassay using an antibody microarray on a polydimethylsiloxane (PDMS) substrate modified with fluorinated compounds to detect tHb and glycosylated hemoglobin A1c (GHbA1c) in human whole blood without sample pretreatment. A polyclonal antibody against hemoglobin (Hb) immobilized on PDMS is used as a common capture probe to enrich all forms of Hb followed by detection via monoclonal anti-Hb and specific monoclonal anti-GHbA1c antibodies for tHb and GHbA1c detection, respectively. This method prevents the use of glycan binding molecules and dramatically reduces the background interference, yielding a detection limit of 3.58 ng/mL for tHb and 0.20 ng/mL for GHbA1c. The fluorinated modification on PDMS is superior to the glass substrate and eliminates the need for the blocking step which is required in commercial enzyme linked immunosorbent assay (ELISA) kits. Moreover, the detection sensitivity for GHbA1c is 4-5 orders of magnitude higher, but the required sample amount is 25 times less than the commercial method. On the basis of patient sample data, a good linear correlation between %GHbA1c values determined by our method and the certified high performance liquid chromatography (HPLC) standard method is shown with R(2) > 0.98, indicating the great promise of the developed method for clinical applications.

Rapid and Sensitive Detection of Cardiac Troponin I for Point-of-Care Tests Based on Red Fluorescent Microspheres.

PubMed

Cai, Yanxue; Kang, Keren; Li, Qianru; Wang, Yu; He, Xiaowei

2018-05-07

A reliable lateral flow immunoassay (LFIA) based on a facile one-step synthesis of single microspheres in combining with immunochromatography technique was developed to establish a new point-of-care test (POCT) for the rapid and early detection of cardiac troponin I (cTnI), a kind of cardiac specific biomarker for acute myocardial infarction (AMI). The double layered microspheres with clear core-shell structures were produced using soap-free emulsion polymerization method with inexpensive compounds (styrene and acrylic acid). The synthetic process was simple, rapid and easy to control due to one-step synthesis without any complicated procedures. The microspheres are nanostructure with high surface area, which have numerous carboxyl groups on the out layer, resulting in high-efficiency coupling between the carrier and antibody via amide bond. Meanwhile, the red fluorescent dye, Nile-red (NR), was wrapped inside the microspheres to improve its stability, as well to reduce the background noise, because of its higher emission wavelength than interference from real plasma samples. The core-shell structures provided different functional areas to separate antibody and dyes, so the immunoassay has highly sensitive, wide working curves in the range of 0⁻40 ng/mL, low limits of detection (LOD) at 0.016 ng/mL, and limits of quantification (LOQ) at 0.087 ng/mL with coefficient of variations (CV) of 10%. This strategy suggested an outstanding platform for LFIA, with good reproducibility and stability to straightforwardly analyze the plasma samples without washing steps, thereby reducing the operating procedures for non-professionals and promoting detection efficiency. The whole detection process can be completed in less than 15 min. This novel immunoassay offers a reliable and favorable analytical result by detecting the real samples, indicating that it holds great potential as a new alternative for biomolecule detection in complex samples, for the early detection of cardiac specific biomarkers.

A reduced graphene oxide based electrochemical biosensor for tyrosine detection

NASA Astrophysics Data System (ADS)

Wei, Junhua; Qiu, Jingjing; Li, Li; Ren, Liqiang; Zhang, Xianwen; Chaudhuri, Jharna; Wang, Shiren

2012-08-01

In this paper, a ‘green’ and safe hydrothermal method has been used to reduce graphene oxide and produce hemin modified graphene nanosheet (HGN) based electrochemical biosensors for the determination of l-tyrosine levels. The as-fabricated HGN biosensors were characterized by UV-visible absorption spectra, fluorescence spectra, Fourier transform infrared spectroscopy (FTIR) spectra and thermogravimetric analysis (TGA). The experimental results indicated that hemin was successfully immobilized on the reduced graphene oxide nanosheet (rGO) through π-π interaction. TEM images and EDX results further confirmed the attachment of hemin on the rGO nanosheet. Cyclic voltammetry tests were carried out for the bare glass carbon electrode (GCE), the rGO electrode (rGO/GCE), and the hemin-rGO electrode (HGN/GCE). The HGN/GCE based biosensor exhibits a tyrosine detection linear range from 5 × 10-7 M to 2 × 10-5 M with a detection limitation of 7.5 × 10-8 M at a signal-to-noise ratio of 3. The sensitivity of this biosensor is 133 times higher than that of the bare GCE. In comparison with other works, electroactive biosensors are easily fabricated, easily controlled and cost-effective. Moreover, the hemin-rGO based biosensors demonstrate higher stability, a broader detection linear range and better detection sensitivity. Study of the oxidation scheme reveals that the rGO enhances the electron transfer between the electrode and the hemin, and the existence of hemin groups effectively electrocatalyzes the oxidation of tyrosine. This study contributes to a widespread clinical application of nanomaterial based biosensor devices with a broader detection linear range, improved stability, enhanced sensitivity and reduced costs.

A reduced graphene oxide based electrochemical biosensor for tyrosine detection.

PubMed

Wei, Junhua; Qiu, Jingjing; Li, Li; Ren, Liqiang; Zhang, Xianwen; Chaudhuri, Jharna; Wang, Shiren

2012-08-24

In this paper, a 'green' and safe hydrothermal method has been used to reduce graphene oxide and produce hemin modified graphene nanosheet (HGN) based electrochemical biosensors for the determination of l-tyrosine levels. The as-fabricated HGN biosensors were characterized by UV-visible absorption spectra, fluorescence spectra, Fourier transform infrared spectroscopy (FTIR) spectra and thermogravimetric analysis (TGA). The experimental results indicated that hemin was successfully immobilized on the reduced graphene oxide nanosheet (rGO) through π-π interaction. TEM images and EDX results further confirmed the attachment of hemin on the rGO nanosheet. Cyclic voltammetry tests were carried out for the bare glass carbon electrode (GCE), the rGO electrode (rGO/GCE), and the hemin-rGO electrode (HGN/GCE). The HGN/GCE based biosensor exhibits a tyrosine detection linear range from 5 × 10(-7) M to 2 × 10(-5) M with a detection limitation of 7.5 × 10(-8) M at a signal-to-noise ratio of 3. The sensitivity of this biosensor is 133 times higher than that of the bare GCE. In comparison with other works, electroactive biosensors are easily fabricated, easily controlled and cost-effective. Moreover, the hemin-rGO based biosensors demonstrate higher stability, a broader detection linear range and better detection sensitivity. Study of the oxidation scheme reveals that the rGO enhances the electron transfer between the electrode and the hemin, and the existence of hemin groups effectively electrocatalyzes the oxidation of tyrosine. This study contributes to a widespread clinical application of nanomaterial based biosensor devices with a broader detection linear range, improved stability, enhanced sensitivity and reduced costs.

Dual Recognition Strategy for Specific and Sensitive Detection of Bacteria Using Aptamer-Coated Magnetic Beads and Antibiotic-Capped Gold Nanoclusters.

PubMed

Cheng, Dan; Yu, Mengqun; Fu, Fei; Han, Weiye; Li, Gan; Xie, Jianping; Song, Yang; Swihart, Mark T; Song, Erqun

2016-01-05

Food poisoning and infectious diseases caused by pathogenic bacteria such as Staphylococcus aureus (SA) are serious public health concerns. A method of specific, sensitive, and rapid detection of such bacteria is essential and important. This study presents a strategy that combines aptamer and antibiotic-based dual recognition units with magnetic enrichment and fluorescent detection to achieve specific and sensitive quantification of SA in authentic specimens and in the presence of much higher concentrations of other bacteria. Aptamer-coated magnetic beads (Apt-MB) were employed for specific capture of SA. Vancomycin-stabilized fluorescent gold nanoclusters (AuNCs@Van) were prepared by a simple one-step process and used for sensitive quantification of SA in the range of 32-10(8) cfu/mL with the detection limit of 16 cfu/mL via a fluorescence intensity measurement. And using this strategy, about 70 cfu/mL of SA in complex samples (containing 3 × 10(8) cfu/mL of other different contaminated bacteria) could be successfully detected. In comparison to prior studies, the developed strategy here not only simplifies the preparation procedure of the fluorescent probes (AuNCs@Van) to a great extent but also could sensitively quantify SA in the presence of much higher concentrations of other bacteria directly with good accuracy. Moreover, the aptamer and antibiotic used in this strategy are much less expensive and widely available compared to common-used antibodies, making it cost-effective. This general aptamer- and antibiotic-based dual recognition strategy, combined with magnetic enrichment and fluorescent detection of trace bacteria, shows great potential application in monitoring bacterial food contamination and infectious diseases.

X-ray emission from a complete sample of Abell clusters of galaxies

NASA Astrophysics Data System (ADS)

Briel, Ulrich G.; Henry, J. Patrick

1993-11-01

The ROSAT All-Sky Survey (RASS) is used to investigate the X-ray properties of a complete sample of Abell clusters with measured redshifts and accurate positions. The sample comprises the 145 clusters within a 561 square degree region at high galactic latitude. The mean redshift is 0.17. This sample is especially well suited to be studied within the RASS since the mean exposure time is higher than average and the mean galactic column density is very low. These together produce a flux limit of about 4.2 x 10-13 erg/sq cm/s in the 0.5 to 2.5 keV energy band. Sixty-six (46%) individual clusters are detected at a significance level higher than 99.7% of which 7 could be chance coincidences of background or foreground sources. At redshifts greater than 0.3 six clusters out of seven (86%) are detected at the same significance level. The detected objects show a clear X-ray luminosity -- galaxy count relation with a dispersion consistent with other external estimates of the error in the counts. By analyzing the excess of positive fluctuations of the X-ray flux at the cluster positions, compared with the fluctuations of randomly drawn background fields, it is possible to extend these results below the nominal flux limit. We find 80% of richness R greater than or = 0 and 86% of R greater than or = 1 clusters are X-ray emitters with fluxes above 1 x 10-13 erg/sq cm/s. Nearly 90% of the clusters meeting the requirements to be in Abell's statistical sample emit above the same level. We therefore conclude that almost all Abell clusters are real clusters and the Abell catalog is not strongly contaminated by projection effects. We use the Kaplan-Meier product limit estimator to calculate the cumulative X-ray luminosity function. We show that the shape of the luminosity functions are similiar for different richness classes, but the characteristic luminosities of richness 2 clusters are about twice those of richness 1 clusters which are in turn about twice those of richness 0 clusters. This result is another manifestation of the luminosity -- richness elation for Abell clusters.

Desmocollin 2 is a new immunohistochemical marker indicative of squamous differentiation in urothelial carcinoma.

PubMed

Hayashi, Tetsutaro; Sentani, Kazuhiro; Oue, Naohide; Anami, Katsuhiro; Sakamoto, Naoya; Ohara, Shinya; Teishima, Jun; Noguchi, Tsuyoshi; Nakayama, Hirofumi; Taniyama, Kiyomi; Matsubara, Akio; Yasui, Wataru

2011-10-01

Urothelial carcinoma (UC) with squamous differentiation tends to present at higher stages than pure UC. To distinguish UC with squamous differentiation from pure UC, a sensitive and specific marker is needed. Desmocollin 2 (DSC2) is a protein localized in desmosomal junctions of stratified epithelium, but little is known about its biological significance in bladder cancer. We examined the utility of DSC2 as a diagnostic marker. We analysed the immunohistochemical characteristics of DSC2, and studied the relationship of DSC2 expression with the expression of the known markers uroplakin III (UPIII), cytokeratin (CK)7, CK20, epidermal growth factor receptor (EGFR), and p53. DSC2 staining was detected in 24 of 25 (96%) cases of UC with squamous differentiation, but in none of 85 (0%) cases of pure UC. DSC2 staining was detected only in areas of squamous differentiation. DSC2 expression was mutually exclusive of UPIII expression, and was correlated with EGFR expression. Furthermore, DSC2 expression was correlated with higher stage (P = 0.0314) and poor prognosis (P = 0.0477). DSC2 staining offers high sensitivity (96%) and high specificity (100%) for the detection of squamous differentiation in UC. DSC2 is a useful immunohistochemical marker for separation of UC with squamous differentiation from pure UC. 2011 Blackwell Publishing Limited.

Loop-mediated isothermal amplification (LAMP) based detection of Colletotrichum falcatum causing red rot in sugarcane.

PubMed

Chandra, Amaresh; Keizerweerd, Amber T; Que, Youxiong; Grisham, Michael P

2015-08-01

Red rot, caused by Colletotrichum falcatum, is a destructive disease prevalent in most sugarcane-producing countries. Disease-free sugarcane planting materials (setts) are essential as the pathogen spreads primarily through infected setts. The present study was undertaken to develop a loop-mediated isothermal amplification (LAMP) assay for the detection of C. falcatum. C. falcatum genomic DNA was isolated from pure mycelium culture and infected tissues. Four sets of primers corresponding to a unique DNA sequence specific to C. falcatum were designed. Specificity of the LAMP test was checked with DNA of another fungal pathogen of sugarcane, Puccinia melanocephala, as well as two closely-related species, Colletotrichum fructivorum and Colletotrichum acutatum. No reaction was found with the three pathogens. When C. falcatum DNA from pure culture was used in a detection limit analysis, sensitivity of the LAMP method was observed to be ten times higher than that of conventional PCR; however, sensitivity was only 5 times higher when DNA from C. falcatum-infected tissues was used. Using the LAMP assay, C. falcatum DNA is amplified with high specificity, efficiency, and rapidity under isothermal conditions. Moreover, visual judgment of color change in <1 h without further post-amplification processing makes the LAMP method convenient, economical, and useful in diagnostic laboratories and the field.

Blue-light photoelectrochemical sensor based on nickel tetra-amined phthalocyanine-graphene oxide covalent compound for ultrasensitive detection of erythromycin.

PubMed

Peng, Jinyun; Huang, Qing; Zhuge, Wenfeng; Liu, Yuxia; Zhang, Cuizong; Yang, Wei; Xiang, Gang

2018-05-30

In this study, we developed a novel photoelectrochemical (PEC) sensor for the highly sensitive detection of erythromycin by functionalising graphene oxide (GO) with nickel tetra-amined phthalocyanine (NiTAPc) through covalent bonding, which resulted in the formation of NiTAPc-Gr. The fabricated sensor showed a higher PEC efficiency under blue light, exhibiting a peak wavelength of 456 nm, as compared to that of the monomer. Further, the NiTAPc-Gr/indium tin oxide (ITO) sensor exhibited a photocurrent that was 50-fold higher than that for a GO/ITO sensor under the same conditions. Under optimal conditions, the NiTAPc-Gr PEC sensor showed a linear response for erythromycin concentrations ranging from 0.40 to 120.00 μmol L -1 , with the minimum limit for detection being 0.08 μmol L -1 . Thus, the NiTAPc-Gr sensor exhibited superior performance and excellent PEC characteristics, high stability, and good reproducibility with respect to the sensing of erythromycin. Moreover, it is convenient to use, fast, small, and cheap to produce. Hence, it should find wide use in the analysis of erythromycin in real-world applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Multiplex enrichment quantitative PCR (ME-qPCR): a high-throughput, highly sensitive detection method for GMO identification.

PubMed

Fu, Wei; Zhu, Pengyu; Wei, Shuang; Zhixin, Du; Wang, Chenguang; Wu, Xiyang; Li, Feiwu; Zhu, Shuifang

2017-04-01

Among all of the high-throughput detection methods, PCR-based methodologies are regarded as the most cost-efficient and feasible methodologies compared with the next-generation sequencing or ChIP-based methods. However, the PCR-based methods can only achieve multiplex detection up to 15-plex due to limitations imposed by the multiplex primer interactions. The detection throughput cannot meet the demands of high-throughput detection, such as SNP or gene expression analysis. Therefore, in our study, we have developed a new high-throughput PCR-based detection method, multiplex enrichment quantitative PCR (ME-qPCR), which is a combination of qPCR and nested PCR. The GMO content detection results in our study showed that ME-qPCR could achieve high-throughput detection up to 26-plex. Compared to the original qPCR, the Ct values of ME-qPCR were lower for the same group, which showed that ME-qPCR sensitivity is higher than the original qPCR. The absolute limit of detection for ME-qPCR could achieve levels as low as a single copy of the plant genome. Moreover, the specificity results showed that no cross-amplification occurred for irrelevant GMO events. After evaluation of all of the parameters, a practical evaluation was performed with different foods. The more stable amplification results, compared to qPCR, showed that ME-qPCR was suitable for GMO detection in foods. In conclusion, ME-qPCR achieved sensitive, high-throughput GMO detection in complex substrates, such as crops or food samples. In the future, ME-qPCR-based GMO content identification may positively impact SNP analysis or multiplex gene expression of food or agricultural samples. Graphical abstract For the first-step amplification, four primers (A, B, C, and D) have been added into the reaction volume. In this manner, four kinds of amplicons have been generated. All of these four amplicons could be regarded as the target of second-step PCR. For the second-step amplification, three parallels have been taken for the final evaluation. After the second evaluation, the final amplification curves and melting curves have been achieved.

In-vivo digital wavefront sensing using swept source OCT

PubMed Central

Kumar, Abhishek; Wurster, Lara M.; Salas, Matthias; Ginner, Laurin; Drexler, Wolfgang; Leitgeb, Rainer A.

2017-01-01

Sub-aperture based digital adaptive optics is demonstrated in a fiber based point scanning optical coherence tomography system using a 1060 nm swept source laser. To detect optical aberrations in-vivo, a small lateral field of view of ~150×150 μm2 is scanned on the sample at a high volume rate of 17 Hz (~1.3 kHz B-scan rate) to avoid any significant lateral and axial motion of the sample, and is used as a “guide star” for the sub-aperture based DAO. The proof of principle is demonstrated using a micro-beads phantom sample, wherein a significant root mean square wavefront error (RMS WFE) of 1.48 waves (> 1μm) is detected. In-vivo aberration measurement with a RMS WFE of 0.33 waves, which is ~5 times higher than the Marechal’s criterion of 1/14 waves for the diffraction limited performance, is shown for a human retinal OCT. Attempt has been made to validate the experimental results with the conventional Shack-Hartmann wavefront sensor within reasonable limitations. PMID:28717573

The effect of ultrafast laser wavelength on ablation properties and implications on sample introduction in inductively coupled plasma mass spectrometry

PubMed Central

LaHaye, N. L.; Harilal, S. S.; Diwakar, P. K.; Hassanein, A.; Kulkarni, P.

2015-01-01

We investigated the role of femtosecond (fs) laser wavelength on laser ablation (LA) and its relation to laser generated aerosol counts and particle distribution, inductively coupled plasma-mass spectrometry (ICP-MS) signal intensity, detection limits, and elemental fractionation. Four different NIST standard reference materials (610, 613, 615, and 616) were ablated using 400 nm and 800 nm fs laser pulses to study the effect of wavelength on laser ablation rate, accuracy, precision, and fractionation. Our results show that the detection limits are lower for 400 nm laser excitation than 800 nm laser excitation at lower laser energies but approximately equal at higher energies. Ablation threshold was also found to be lower for 400 nm than 800 nm laser excitation. Particle size distributions are very similar for 400 nm and 800 nm wavelengths; however, they differ significantly in counts at similar laser fluence levels. This study concludes that 400 nm LA is more beneficial for sample introduction in ICP-MS, particularly when lower laser energies are to be used for ablation. PMID:26640294

Bioavailability, ecotoxicity, and geological characteristics of trace lead in sediments from two sites on Negro River, Uruguay, South America.

PubMed

Míguez, Diana M; Huertas, Raquel; Carrara, María V; Carnikián, Agustín; Bouvier, María E; Martínez, María J; Keel, Karen; Pioda, Carolina; Darré, Elena; Pérez, Ramiro; Viera, Santiago; Massa, Enrique

2012-04-01

Bioassays of two sites along the Rio Negro in Uruguay indicate ecotoxicity, which could be attributable to trace concentrations of lead in river sediments. Monthly samples at two sites at Baygorria and Bonete locations were analyzed for both particle size and lead. Lead was determined by atomic spectrometry in river water and sediment and particle size by sieving and sedimentation. Data showed that Baygorria's sediments have greater percentage of clay than Bonete's (20.4 and 5.8%, respectively). Lead was measurable in Baygorria's sediments, meanwhile in Bonete's, it was always below the detection limit. In water samples, lead was below detection limit at both sites. Bioassays using sub-lethal growth and survival test with Hyalella curvispina amphipod, screening with bioluminescent bacteria Photobacterium leiognathi, and acute toxicity bioassay with Pimephales promelas fish indicated toxicity at Baygorria, with much less effect at Bonete. Even though no lethal effects could be demonstrated, higher sub-lethal toxicity was found in samples from Baygorria site, showing a possible concentration of the contaminant in the clay fraction.

Use of propidium monoazide for the enumeration of viable Brettanomyces bruxellensis in wine and beer by quantitative PCR.

PubMed

Vendrame, Marco; Manzano, Marisa; Comi, Giuseppe; Bertrand, Julien; Iacumin, Lucilla

2014-09-01

Brettanomyces bruxellensis is a current problem in winemaking all over the world, and the question if B. bruxellensis has a positive or negative impact on wine is one of the most controversial discussions in the world. The presence of live B. bruxellensis cells represents the risk of growth and an increase in cell numbers, which is related to the potential production of volatile phenols. In this work, the optimisation of a PMA-quantitative PCR (qPCR) method to enumerate only viable cells was carried out using the standard strain B. bruxellensis DSMZ 70726. The obtained detection limits were 0.83 log CFU/mL in red wine, 0.63 log CFU/mL in white wine and 0.23 log CFU/mL in beer. Moreover, the quantification was also performed by Reverse Transcription quantitative PCR (RT-qPCR), and the results showed a higher detection limit for all of the trials. Copyright © 2014 Elsevier Ltd. All rights reserved.

Maintaining access to safe abortion and reducing sex ratio imbalances in Asia.

PubMed

Ganatra, Bela

2008-05-01

High sex ratios at birth (108 boys to 100 girls or higher) are seen in China, Taiwan, South Korea and parts of India and Viet Nam. The imbalance is the result of son preference, accentuated by declining fertility. Prenatal sex detection with ultrasound followed by second trimester abortion is one of the ways sex selection manifests itself, but it is not the causative factor. Advocates and governments seeking to reverse this imbalance have largely prohibited sex detection tests and/or sex selective abortion, assuming these measures would reverse the trend. Such policies have been difficult to enforce and have met with only limited success. At the same time, such policies are starting to have adverse effects on the already limited access to safe and legal second trimester abortion for reasons other than sex selection. Moreover, the sex selection issue is being used as a platform for anti-abortion rhetoric by certain groups. Maintaining access to safe abortion and achieving a decline in high sex ratios are both important goals. Both are possible if the focus shifts to addressing the conditions that drive son preference.

Atmospheric PCB concentrations at Terra Nova Bay, Antarctica.

PubMed

Gambaro, Andrea; Manodori, Laura; Zangrando, Roberta; Cincinelli, Alessandra; Capodaglio, Gabriele; Cescon, Paolo

2005-12-15

Concentrations of gas-phase polychlorobiphenyls (PCBs) were studied over an austral summer at a site in Terra Nova Bay, Antarctica. Gas-phase concentrations of individual PCB congeners in the atmosphere of Terra Nova Bay ranged from below the detection limit to 0.25 pg m(-3), with a mean concentration of sigmaPCB of 1.06 pg m(-3). The PCB profile was dominated by lower-chlorinated PCB congeners; in fact >78% of the total PCB content was due to congeners with 1-4 chlorine atoms and only about 10% with 5-7 chlorines, whereas higher-chlorinated PCB congeners were below detection limits. The mean sigmaPCB concentration obtained in this study were lower than those reported in previous Antarctic studies. Temporal concentration profiles of sigmaPCB do not correspond to seasonal temperature changes. In consideration of the low PCB concentrations observed, the studies with the wind roses, the regression between In P(PCB) and T(-1), and the distribution of congeners, we can hypothesize that PCB local source contributions are not very important, whereas long-distance transport is the prevalent factor bringing PCBs to Terra Nova Bay.

Detection and quantification of cocaine and benzoylecgonine in meconium using solid phase extraction and UPLC/MS/MS.

PubMed

Gunn, Josh; Kriger, Scott; Terrell, Andrea R

2010-01-01

The simultaneous determination and quantification of cocaine and its major metabolite, benzoylecgonine, in meconium using UPLC-MS/MS is described. Ultra-performance liquid chromatography (UPLC) is an emerging analytical technique which draws upon the principles of chromatography to run separations at higher flow rates for increased speed, while simultaneously achieving superior resolution and sensitivity. Extraction of cocaine and benzoylecgonine from the homogenized meconium matrix was achieved with a preliminary protein precipitation or protein 'crash' employing cold acetonitrile, followed by a mixed mode solid phase extraction (SPE). Following elution from the SPE cartridge, eluents were dried down under nitrogen, reconstituted in 200 microL of DI water:acetonitrile (ACN) (75:25), and injected onto the UPLC/MS/MS for analysis. The increased speed and separation efficiency afforded by UPLC, allowed for the separation and subsequent quantification of both analytes in less than 2 min. Analytes were quantified using multiple reaction monitoring (MRM) and six-point calibration curves constructed in negative blood. Limits of detection for both analytes were 3 ng/g and the lower limit of quantitation (LLOQ) was 30 ng/g.

Visual acuity of the honey bee retina and the limits for feature detection.

PubMed

Rigosi, Elisa; Wiederman, Steven D; O'Carroll, David C

2017-04-06

Visual abilities of the honey bee have been studied for more than 100 years, recently revealing unexpectedly sophisticated cognitive skills rivalling those of vertebrates. However, the physiological limits of the honey bee eye have been largely unaddressed and only studied in an unnatural, dark state. Using a bright display and intracellular recordings, we here systematically investigated the angular sensitivity across the light adapted eye of honey bee foragers. Angular sensitivity is a measure of photoreceptor receptive field size and thus small values indicate higher visual acuity. Our recordings reveal a fronto-ventral acute zone in which angular sensitivity falls below 1.9°, some 30% smaller than previously reported. By measuring receptor noise and responses to moving dark objects, we also obtained direct measures of the smallest features detectable by the retina. In the frontal eye, single photoreceptors respond to objects as small as 0.6° × 0.6°, with >99% reliability. This indicates that honey bee foragers possess significantly better resolution than previously reported or estimated behaviourally, and commonly assumed in modelling of bee acuity.

Acetone gas sensor based on NiO/ZnO hollow spheres: Fast response and recovery, and low (ppb) detection limit.

PubMed

Liu, Chang; Zhao, Liupeng; Wang, Boqun; Sun, Peng; Wang, Qingji; Gao, Yuan; Liang, Xishuang; Zhang, Tong; Lu, Geyu

2017-06-01

NiO/ZnO composites were synthesized by decorating numerous NiO nanoparticles on the surfaces of well dispersed ZnO hollow spheres using a facile solvothermal method. Various kinds of characterization methods were utilized to investigate the structures and morphologies of the hybrid materials. The results revealed that the NiO nanoparticles with a size of ∼10nm were successfully distributed on the surfaces of ZnO hollow spheres in a discrete manner. As expected, the NiO/ZnO composites demonstrated dramatic improvements in sensing performances compared with pure ZnO hollow spheres. For example, the response of NiO/ZnO composites to 100ppm acetone was ∼29.8, which was nearly 4.6 times higher than that of primary ZnO at 275°C, and the response/recovery time were 1/20s, respectively. Meanwhile, the detection limit could extend down to ppb level. The likely reason for the improved gas sensing properties was also proposed. Copyright © 2017 Elsevier Inc. All rights reserved.

Dissipation rate study and pre-harvest intervals calculation of imidacloprid and oxamyl in exported Egyptian green beans and chili peppers after pestigation treatment.

PubMed

Hanafi, Ahmad; Dasenaki, Marilena; Bletsou, Anna; Thomaidis, Nikolaos S

2018-02-01

Two QuEChERS-based methods were developed and validated, using liquid chromatography-tandem mass spectrometric detection, in order to accurately determine residues of imidacloprid and oxamyl in green beans and chili peppers after treatment via irrigation system under field conditions in Egyptian farms. The validation included experiments for specificity, linearity, trueness, precision, matrix effect and limits of detection and quantification according to European Commission standards. The dissipation rates of both pesticides in green beans and chili peppers were studied and the pre-harvest intervals (PHIs) were calculated. The LOQ values of imidacloprid were 0.47 and 2.6μg/kg in green beans and chili peppers, respectively, while for oxamyl the LOQs were 2.9 and 0.67μg/kg, respectively. No PHI of imidacloprid is required, while for oxamyl it was found that still after 21days, its residues' concentration on both crops was significantly higher than the maximum residue limit. Copyright © 2017 Elsevier Ltd. All rights reserved.

Joint reconstruction of x-ray fluorescence and transmission tomography

DOE PAGES

Di, Zichao; Chen, Si; Hong, Young Pyo; ...

2017-05-30

X-ray fluorescence tomography is based on the detection of fluorescence x-ray photons produced following x-ray absorption while a specimen is rotated; it provides information on the 3D distribution of selected elements within a sample. One limitation in the quality of sample recovery is the separation of elemental signals due to the finite energy resolution of the detector. Another limitation is the effect of self-absorption, which can lead to inaccurate results with dense samples. To recover a higher quality elemental map, we combine x-ray fluorescence detection with a second data modality: conventional x-ray transmission tomography using absorption. By using these combinedmore » signals in a nonlinear optimization-based approach, we demonstrate the benefit of our algorithm on real experimental data and obtain an improved quantitative reconstruction of the spatial distribution of dominant elements in the sample. Furthermore, compared with single-modality inversion based on x-ray fluorescence alone, this joint inversion approach reduces ill-posedness and should result in improved elemental quantification and better correction of self-absorption.« less

Establishing the behavioural limits for countershaded camouflage.

PubMed

Penacchio, Olivier; Harris, Julie M; Lovell, P George

2017-10-20

Countershading is a ubiquitous patterning of animals whereby the side that typically faces the highest illumination is darker. When tuned to specific lighting conditions and body orientation with respect to the light field, countershading minimizes the gradient of light the body reflects by counterbalancing shadowing due to illumination, and has therefore classically been thought of as an adaptation for visual camouflage. However, whether and how crypsis degrades when body orientation with respect to the light field is non-optimal has never been studied. We tested the behavioural limits on body orientation for countershading to deliver effective visual camouflage. We asked human participants to detect a countershaded target in a simulated three-dimensional environment. The target was optimally coloured for crypsis in a reference orientation and was displayed at different orientations. Search performance dramatically improved for deviations beyond 15 degrees. Detection time was significantly shorter and accuracy significantly higher than when the target orientation matched the countershading pattern. This work demonstrates the importance of maintaining body orientation appropriate for the displayed camouflage pattern, suggesting a possible selective pressure for animals to orient themselves appropriately to enhance crypsis.

Coherent scattering noise reduction method with wavelength diversity detection for holographic data storage system

NASA Astrophysics Data System (ADS)

Nakamura, Yusuke; Hoshizawa, Taku; Takashima, Yuzuru

2017-09-01

A new method, wavelength diversity detection (WDD), for improving signal quality is proposed and its effectiveness is numerically confirmed. We consider that WDD is especially effective for high-capacity systems having low hologram diffraction efficiencies. In such systems, the signal quality is primarily limited by coherent scattering noise; thus, effective improvement of the signal quality under a scattering-limited system is of great interest. WDD utilizes a new degree of freedom, the spectrum width, and scattering by molecules to improve the signal quality of the system. We found that WDD improves the quality by counterbalancing the degradation of the quality due to Bragg mismatch. With WDD, a higher-scattering-coefficient medium can improve the quality. The result provides an interesting insight into the requirements for material characteristics, especially for a large-M/# material. In general, a larger-M/# material contains more molecules; thus, the system is subject to more scattering, which actually improves the quality with WDD. We propose a pathway for a future holographic data storage system (HDSS) using WDD, which can record a larger amount of data than a conventional HDSS.

Degradation pathway of 2-chloroethanol in Pseudomonas stutzeri strain JJ under denitrifying conditions.

PubMed

Dijk, John A; Gerritse, Jan; Schraa, Gosse; Stams, Alfons J M

2004-12-01

The pathway of 2-chloroethanol degradation in the denitrifying Pseudomonas stutzeri strain JJ was investigated. In cell-free extracts, activities of a phenazine methosulfate (PMS)-dependent chloroethanol dehydrogenase, an NAD-dependent chloroacetaldehyde dehydrogenase, and a chloroacetate dehalogenase were detected. This suggested that the 2-chloroethanol degradation pathway in this denitrifying strain is the same as found in aerobic bacteria that degrade chloroethanol. Activity towards primary alcohols, secondary alcohols, diols, and other chlorinated alcohols could be measured in cell-free extracts with chloroethanol dehydrogenase (CE-DH) activity. PMS and phenazine ethosulfate (PES) were used as primary electron acceptors, but not NAD, NADP or ferricyanide. Cells of strain JJ cultured in a continuous culture under nitrate limitation exhibited chloroethanol dehydrogenase activity that was a 12 times higher than in cells grown in batch culture. However, under chloroethanol-limiting conditions, CE-DH activity was in the same range as in batch culture. Cells grown on ethanol did not exhibit CE-DH activity. Instead, NAD-dependent ethanol dehydrogenase (E-DH) activity and PMS-dependent E-DH activity were detected.

Disposable sensor based on enzyme-free Ni nanowire array electrode to detect glutamate.

PubMed

Jamal, Mamun; Hasan, Maksudul; Mathewson, Alan; Razeeb, Kafil M

2013-02-15

Enzyme free electrochemical sensor platform based on a vertically aligned nickel nanowire array (NiNAE) and Pt coated nickel nanowire array (Pt/NiNAE) have been developed to detect glutamate. Morphological characterisation of Ni electrodes was carried out using scanning and transmission electron microscopy combined with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the NiNAE and the Pt/NiNAE for glutamate. It has been found that both NiNAE and Pt/NiNAE electrodes showed remarkably enhanced electrocatalytic activity towards glutamate compared to planar Ni electrodes, and showed higher catalytic activity when compared to other metallic nanostructure electrodes such as gold nanowire array electrodes (AuNAE) and Pt coated gold nanowire array electrode (Pt/AuNAE). The sensitivity of NiNAE and Pt/NiNAE has been found to be 65 and 96 μA mM(-1) cm(-2), respectively, which is approximately 6 to 9 times higher than the state of the art glutamate sensor. Under optimal detection conditions, the as prepared sensors exhibited linear behaviour for glutamate detection in the concentration up to 8mM for both NiNAE and Pt/NiNAE with a limit of detection of 68 and 83 μM, respectively. Experimental results show that the vertically aligned ordered nickel nanowire array electrode (NiNAE) has significant promise for fabricating cost effective, enzyme-less, sensitive, stable and selective sensor platform. Copyright © 2012 Elsevier B.V. All rights reserved.

An ultrasensitive bio-surrogate for nanoporous filter membrane performance metrology directed towards contamination control in microlithography applications

NASA Astrophysics Data System (ADS)

Ahmad, Farhan; Mish, Barbara; Qiu, Jian; Singh, Amarnauth; Varanasi, Rao; Bedford, Eilidh; Smith, Martin

2016-03-01

Contamination tolerances in semiconductor manufacturing processes have changed dramatically in the past two decades, reaching below 20 nm according to the guidelines of the International Technology Roadmap for Semiconductors. The move to narrower line widths drives the need for innovative filtration technologies that can achieve higher particle/contaminant removal performance resulting in cleaner process fluids. Nanoporous filter membrane metrology tools that have been the workhorse over the past decade are also now reaching limits. For example, nanoparticle (NP) challenge testing is commonly applied for assessing particle retention performance of filter membranes. Factors such as high NP size dispersity, low NP detection sensitivity, and high NP particle-filter affinity impose challenges in characterizing the next generation of nanoporous filter membranes. We report a novel bio-surrogate, 5 nm DNA-dendrimer conjugate for evaluating particle retention performance of nanoporous filter membranes. A technique capable of single molecule detection is employed to detect sparse concentration of conjugate in filter permeate, providing >1000- fold higher detection sensitivity than any existing 5 nm-sized particle enumeration technique. This bio-surrogate also offers narrow size distribution, high stability and chemical tunability. This bio-surrogate can discriminate various sub-15 nm pore-rated nanoporous filter membranes based on their particle retention performance. Due to high bio-surrogate detection sensitivity, a lower challenge concentration of bio-surrogate (as compared to other NPs of this size) can be used for filter testing, providing a better representation of customer applications. This new method should provide better understanding of the next generation filter membranes for removing defect-causing contaminants from lithography processes.

Standardization of a cytometric p24-capture bead-assay for the detection of main HIV-1 subtypes.

PubMed

Merbah, Mélanie; Onkar, Sayali; Grivel, Jean-Charles; Vanpouille, Christophe; Biancotto, Angélique; Bonar, Lydia; Sanders-Buell, Eric; Kijak, Gustavo; Michael, Nelson; Robb, Merlin; Kim, Jerome H; Tovanabutra, Sodsai; Chenine, Agnès-Laurence

2016-04-01

The prevailing method to assess HIV-1 replication and infectivity is to measure the production of p24 Gag protein by enzyme-linked immunosorbent assay (ELISA). Since fluorescent bead-based technologies offer a broader dynamic range and higher sensitivity, this study describes a p24 capture Luminex assay capable of detecting HIV-1 subtypes A-D, circulating recombinant forms (CRF) CRF01_AE and CRF02_AG, which together are responsible for over 90% of HIV-1 infections worldwide. The success of the assay lies in the identification and selection of a cross-reactive capture antibody (clone 183-H12-5C). Fifty-six isolates that belonged to six HIV-1 subtypes and CRFs were successfully detected with p-values below 0.021; limits of detection ranging from 3.7 to 3 × 104 pg/ml. The intra- and inter-assay variation gave coefficient of variations below 6 and 14%, respectively. The 183-bead Luminex assay also displayed higher sensitivity of 91% and 98% compared to commercial p24 ELISA and a previously described Luminex assay. The p24 concentrations measured by the 183-bead Luminex assay showed a significant correlation (R=0.92, p<0.0001) with the data obtained from quantitative real time PCR. This newly developed p24 assay leverages the advantages of the Luminex platform, which include smaller sample volume and simultaneous detection of up to 500 analytes in a single sample, and delivers a valuable tool for the field. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of antibiotic fungicide kasugamycin in irrigation water by high performance liquid chromatography.

PubMed

Sheu, Ceshing; Chen, Shu-Chuan; Lo, Chi-Chu

2010-07-01

A high performance liquid chromatographic (HPLC) analysis method with an ultraviolet (UV) detector and an Aqua C18 (250 x 4.6 mm, Phenomenex) column were applied to analyze the antibiotic fungicide kasugamycin in water. An aromatic sulfonic acid spe column (Backerbond, J. T. Backer) was used to remove the interfering materials from irrigation water. A good linear relation existed between the concentration of the fungicide and the peak area, and correlation coefficient of linearity from 0.1 to 10.2 microg/mL was 0.998. The accuracies expressed as the recoveries of kasugamycin from irrigation water ranged from 112.2 to 111.7 %. The precisions expressed as relative standard deviations (RSD) were found to be below 7.0 %. The quantitative detection limit (LOQ) of kasugamycin in irrigation water was set at 2.2 microg/mL which was 2-times higher than the method detection limit (MDL) 1.03 microg/mL. Electrospray ionization-mass (ESI-MS) and fast-atom bombardment-mass (FAB-MS) were applied to compare the ability of identifying the component of the eluent peak from HPLC, and the result indicated that electrospray ionization-mass (ESI-MS) was more sensitive than fast-atom bombardment-mass (FAB-MS) in the detection of kasugamycin. There was no kasugamycin residue detected in irrigation water samples collected from paddyfields at Wufong, indicated that the residues of kasugamycin in water were less than 2.2 microg/mL, and the risk of water contamination was very low.

Development of a New Microextraction Fiber Combined to On-Line Sample Stacking Capillary Electrophoresis UV Detection for Acidic Drugs Determination in Real Water Samples.

PubMed

Espina-Benitez, Maria; Araujo, Lilia; Prieto, Avismelsi; Navalón, Alberto; Vílchez, José Luis; Valera, Paola; Zambrano, Ana; Dugas, Vincent

2017-07-07

A new analytical method coupling a (off-line) solid-phase microextraction with an on-line capillary electrophoresis (CE) sample enrichment technique was developed for the analysis of ketoprofen, naproxen and clofibric acid from water samples, which are known as contaminants of emerging concern in aquatic environments. New solid-phase microextraction fibers based on physical coupling of chromatographic supports onto epoxy glue coated needle were studied for the off-line preconcentration of these micropollutants. Identification and quantification of such acidic drugs were done by capillary zone electrophoresis (CZE) using ultraviolet diode array detection (DAD). Further enhancement of concentration sensitivity detection was achieved by on-line CE "acetonitrile stacking" preconcentration technique. Among the eight chromatographic supports investigated, Porapak Q sorbent showed higher extraction and preconcentration capacities. The screening of parameters that influence the microextraction process was carried out using a two-level fractional factorial. Optimization of the most relevant parameters was then done through a surface response three-factor Box-Behnken design. The limits of detection and limits of quantification for the three drugs ranged between 0.96 and 1.27 µg∙L -1 and 2.91 and 3.86 µg∙L -1 , respectively. Recovery yields of approximately 95 to 104% were measured. The developed method is simple, precise, accurate, and allows quantification of residues of these micropollutants in Genil River water samples using inexpensive fibers.

Determination of artificial sweeteners by capillary electrophoresis with contactless conductivity detection optimized by hydrodynamic pumping.

PubMed

Stojkovic, Marko; Mai, Thanh Duc; Hauser, Peter C

2013-07-17

The common sweeteners aspartame, cyclamate, saccharin and acesulfame K were determined by capillary electrophoresis with contactless conductivity detection. In order to obtain the best compromise between separation efficiency and analysis time hydrodynamic pumping was imposed during the electrophoresis run employing a sequential injection manifold based on a syringe pump. Band broadening was avoided by using capillaries of a narrow 10 μm internal diameter. The analyses were carried out in an aqueous running buffer consisting of 150 mM 2-(cyclohexylamino)ethanesulfonic acid and 400 mM tris(hydroxymethyl)aminomethane at pH 9.1 in order to render all analytes in the fully deprotonated anionic form. The use of surface modification to eliminate or reverse the electroosmotic flow was not necessary due to the superimposed bulk flow. The use of hydrodynamic pumping allowed easy optimization, either for fast separations (80s) or low detection limits (6.5 μmol L(-1), 5.0 μmol L(-1), 4.0 μmol L(-1) and 3.8 μmol L(-1) for aspartame, cyclamate, saccharin and acesulfame K respectively, at a separation time of 190 s). The conditions for fast separations not only led to higher limits of detection but also to a narrower dynamic range. However, the settings can be changed readily between separations if needed. The four compounds were determined successfully in food samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Multi-Element CZT Array for Nuclear Safeguards Applications

NASA Astrophysics Data System (ADS)

Kwak, S.-W.; Lee, A.-R.; Shin, J.-K.; Park, U.-R.; Park, S.; Kim, Y.; Chung, H.

2016-12-01

Due to its electronic properties, a cadmium zinc telluride (CZT) detector has been used as a hand-held portable nuclear measurement instrument. However, a CZT detector has low detection efficiency because of a limitation of its single crystal growth. To address its low efficiency, we have constructed a portable four-CZT array based gamma-ray spectrometer consisting of a CZT array, electronics for signal processing and software. Its performance has been characterized in terms of energy resolution and detection efficiency using radioactive sources and nuclear materials. Experimental results showed that the detection efficiency of the four-CZT array based gamma-ray spectrometer was much higher than that of a single CZT detector in the array. The FWHMs of the CZT array were 9, 18, and 21 keV at 185.7, 662, and 1,332 keV, respectively. Some gamma-rays in a range of 100 keV to 200 keV were not clear in a single crystal detector while those from the CZT array system were observed to be clear. The energy resolution of the CZT array system was only slightely worse than those of the single CZT detectors. By combining several single crystals and summing signals from each single detector at a digital electronic circuit, the detection efficiency of a CZT array system increased without degradation of its energy resolution. The technique outlined in this paper shows a very promising method for designing a CZT-based gamma-ray spectroscopy that overcomes the fundamental limitations of a small volume CZT detector.

Development of a New Microextraction Fiber Combined to On-Line Sample Stacking Capillary Electrophoresis UV Detection for Acidic Drugs Determination in Real Water Samples

PubMed Central

Araujo, Lilia; Prieto, Avismelsi; Navalón, Alberto; Vílchez, José Luis; Valera, Paola; Zambrano, Ana; Dugas, Vincent

2017-01-01

A new analytical method coupling a (off-line) solid-phase microextraction with an on-line capillary electrophoresis (CE) sample enrichment technique was developed for the analysis of ketoprofen, naproxen and clofibric acid from water samples, which are known as contaminants of emerging concern in aquatic environments. New solid-phase microextraction fibers based on physical coupling of chromatographic supports onto epoxy glue coated needle were studied for the off-line preconcentration of these micropollutants. Identification and quantification of such acidic drugs were done by capillary zone electrophoresis (CZE) using ultraviolet diode array detection (DAD). Further enhancement of concentration sensitivity detection was achieved by on-line CE “acetonitrile stacking” preconcentration technique. Among the eight chromatographic supports investigated, Porapak Q sorbent showed higher extraction and preconcentration capacities. The screening of parameters that influence the microextraction process was carried out using a two-level fractional factorial. Optimization of the most relevant parameters was then done through a surface response three-factor Box-Behnken design. The limits of detection and limits of quantification for the three drugs ranged between 0.96 and 1.27 µg∙L−1 and 2.91 and 3.86 µg∙L−1, respectively. Recovery yields of approximately 95 to 104% were measured. The developed method is simple, precise, accurate, and allows quantification of residues of these micropollutants in Genil River water samples using inexpensive fibers. PMID:28686186

LIMITATIONS ON THE USES OF MULTIMEDIA EXPOSURE MEASUREMENTS FOR MULTIPATHWAY EXPOSURE ASSESSMENT - PART I: HANDLING OBSERVATIONS BELOW DETECTION LIMITS

EPA Science Inventory

Multimedia data from two probability-based exposure studies were investigated in terms of how censoring of non-detects affected estimation of population parameters and associations. Appropriate methods for handling censored below-detection-limit (BDL) values in this context were...