Development of a highly sensitive immunochromatographic detection kit for H5 influenza virus hemagglutinin using silver amplification.

PubMed

Wada, Atsuhiko; Sakoda, Yoshihiro; Oyamada, Takayoshi; Kida, Hiroshi

2011-12-01

H5N1, a highly pathogenic avian influenza virus (HPAIV), has become a serious epizootic threat to the poultry population in Asia. In addition, significant numbers of human cases of HPAIV infection have been reported to date. To prevent the spread of HPAIV among humans and to allow for timely medical intervention, a rapid and high sensitive method is needed to detect and subtype the causative HPAIVs. In the present study, a silver amplification technique used in photographic development was combined with immunochromatography technologies and a highly sensitive and rapid diagnostic test to detect the hemagglutinin of H5 influenza viruses was developed. The sensitivity of the test kit was increased 500 times by silver amplification. The sensitivity of the method was more than 10 times higher than those of conventional rapid influenza diagnostic tests, which detect viral nucleoproteins. The diagnostic system developed in the present study can therefore provide rapid and highly sensitive results and will be useful for diagnosis of H5 HPAIV infection in humans and animals. Copyright © 2011 Elsevier B.V. All rights reserved.

Spatial contrast sensitivity - Effects of age, test-retest, and psychophysical method

NASA Technical Reports Server (NTRS)

Higgins, Kent E.; Jaffe, Myles J.; Caruso, Rafael C.; Demonasterio, Francisco M.

1988-01-01

Two different psychophysical methods were used to test the spatial contrast sensitivity in normal subjects from five age groups. The method of adjustment showed a decline in sensitivity with increasing age at all spatial frequencies, while the forced-choice procedure showed an age-related decline predominantly at high spatial frequencies. It is suggested that a neural component is responsible for this decline.

Rapid concentration and sensitive detection of hookworm ova from wastewater matrices using a real-time PCR method.

PubMed

Gyawali, P; Sidhu, J P S; Ahmed, W; Jagals, P; Toze, S

2015-12-01

The risk of human hookworm infections from land application of wastewater matrices could be high in regions with high hookworm prevalence. A rapid, sensitive and specific hookworm detection method from wastewater matrices is required in order to assess human health risks. Currently available methods used to identify hookworm ova to the species level are time consuming and lack accuracy. In this study, a real-time PCR method was developed for the rapid, sensitive and specific detection of canine hookworm (Ancylostoma caninum) ova from wastewater matrices. A. caninum was chosen because of its morphological similarity to the human hookworm (Ancylostoma duodenale and Necator americanus). The newly developed PCR method has high detection sensitivity with the ability to detect less than one A. caninum ova from 1 L of secondary treated wastewater at the mean threshold cycle (CT) values ranging from 30.1 to 34.3. The method is also able to detect four A. caninum ova from 1 L of raw wastewater and from ∼4 g of treated sludge with mean CT values ranging from 35.6 to 39.8 and 39.8 to 39.9, respectively. The better detection sensitivity obtained for secondary treated wastewater compared to raw wastewater and sludge samples could be attributed to sample turbidity. The proposed method appears to be rapid, sensitive and specific compared to traditional methods and has potential to aid in the public health risk assessment associated with land application of wastewater matrices. Furthermore, the method can be adapted to detect other helminth ova of interest from wastewater matrices. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

[Psychological Well-being of Highly-sensitive Persons in Transition to Parenthood - A Cross-sectional Study].

PubMed

Schmückle, M; Lindert, J; Schmolz, G

2017-12-01

Well-being of highly sensitive people in the transformation period to parenthood is of increasing concern. This study examines whether the transformation period to parenthood has a higher effect on the psychological well-being (PWB) of highly sensitive people than on not highly sensitive people. A cross-sectional study was undertaken of parents (n=614), highly sensitive (n=440) and not highly sensitive (n=174), at the transition to parenthood. Instruments were the Ryff psychological well-being scale. Independent variables and well-being were examined by descriptive and bivariate methods. Well-being of highly sensitive parents is associated with transition to parenthood (b=-10,129; p<0.05) compared to the control group (7.3% of highly sensitive <50% of PWB; 0.6% of not highly sensitive <50% of PWB). As one of the first studies, this examination looks into the data of highly sensitive parents. It can be stated that there is an urgent need for research in this area. Because with a prevalence of 10-20% highly sensitive people within the population, it can be assumed that highly sensitive mostly young parents, could be an important target group of health promotion. © Georg Thieme Verlag KG Stuttgart · New York.

Highly Sensitive and Automated Surface Enhanced Raman Scattering-based Immunoassay for H5N1 Detection with Digital Microfluidics.

PubMed

Wang, Yang; Ruan, Qingyu; Lei, Zhi-Chao; Lin, Shui-Chao; Zhu, Zhi; Zhou, Leiji; Yang, Chaoyong

2018-04-17

Digital microfluidics (DMF) is a powerful platform for a broad range of applications, especially immunoassays having multiple steps, due to the advantages of low reagent consumption and high automatization. Surface enhanced Raman scattering (SERS) has been proven as an attractive method for highly sensitive and multiplex detection, because of its remarkable signal amplification and excellent spatial resolution. Here we propose a SERS-based immunoassay with DMF for rapid, automated, and sensitive detection of disease biomarkers. SERS tags labeled with Raman reporter 4-mercaptobenzoic acid (4-MBA) were synthesized with a core@shell nanostructure and showed strong signals, good uniformity, and high stability. A sandwich immunoassay was designed, in which magnetic beads coated with antibodies were used as solid support to capture antigens from samples to form a beads-antibody-antigen immunocomplex. By labeling the immunocomplex with a detection antibody-functionalized SERS tag, antigen can be sensitively detected through the strong SERS signal. The automation capability of DMF can greatly simplify the assay procedure while reducing the risk of exposure to hazardous samples. Quantitative detection of avian influenza virus H5N1 in buffer and human serum was implemented to demonstrate the utility of the DMF-SERS method. The DMF-SERS method shows excellent sensitivity (LOD of 74 pg/mL) and selectivity for H5N1 detection with less assay time (<1 h) and lower reagent consumption (∼30 μL) compared to the standard ELISA method. Therefore, this DMF-SERS method holds great potentials for automated and sensitive detection of a variety of infectious diseases.

New and highly sensitive assay for L-5-hydroxytryptophan decarboxylase activity by high-performance liquid chromatography-voltammetry.

PubMed

Rahman, M K; Nagatsu, T; Kato, T

1980-12-12

This paper describes a new, inexpensive and highly sensitive assay for aromatic L-amino acid decarboxylase (AADC) activity, using L-5-hydroxytryptophan (L-5-HTP) as substrate, in rat and human brains and serum by high-performance liquid chromatography (HPLC) with voltammetric detection. L-5-HTP was used as substrate and D-5-HTP for the blank. After isolating serotonin (5-HT) formed enzymatically from L-5-HTP on a small Amberlite CG-50 column, the 5-HT was eluted with hydrochloric acid and assayed by HPLC with a voltammetric detector. N-Methyldopamine was added to each incubation mixture as an internal standard. This method is sensitive enough to measure 5-HT, formed by the enzyme, 100 fmol to 140 pmol or more. An advantage of this method is that one can incubate the enzyme for longer time (up to 150 min), as compared with AADC assay using L-DOPA as substrate, resulting in a very high sensitivity. By using this new method, AADC activity was discovered in rat serum.

Multiplexed Simultaneous High Sensitivity Sensors with High-Order Mode Based on the Integration of Photonic Crystal 1 × 3 Beam Splitter and Three Different Single-Slot PCNCs.

PubMed

Zhou, Jian; Huang, Lijun; Fu, Zhongyuan; Sun, Fujun; Tian, Huiping

2016-07-07

We simulated an efficient method for the sensor array of high-sensitivity single-slot photonic crystal nanobeam cavities (PCNCs) on a silicon platform. With the combination of a well-designed photonic crystal waveguide (PhCW) filter and an elaborate single-slot PCNC, a specific high-order resonant mode was filtered for sensing. A 1 × 3 beam splitter carefully established was implemented to split channels and integrate three sensors to realize microarrays. By applying the three-dimensional finite-difference-time-domain (3D-FDTD) method, the sensitivities calculated were S₁ = 492 nm/RIU, S₂ = 244 nm/RIU, and S₃ = 552 nm/RIU, respectively. To the best of our knowledge, this is the first multiplexing design in which each sensor cite features such a high sensitivity simultaneously.

Multiplexed Simultaneous High Sensitivity Sensors with High-Order Mode Based on the Integration of Photonic Crystal 1 × 3 Beam Splitter and Three Different Single-Slot PCNCs

PubMed Central

Zhou, Jian; Huang, Lijun; Fu, Zhongyuan; Sun, Fujun; Tian, Huiping

2016-01-01

We simulated an efficient method for the sensor array of high-sensitivity single-slot photonic crystal nanobeam cavities (PCNCs) on a silicon platform. With the combination of a well-designed photonic crystal waveguide (PhCW) filter and an elaborate single-slot PCNC, a specific high-order resonant mode was filtered for sensing. A 1 × 3 beam splitter carefully established was implemented to split channels and integrate three sensors to realize microarrays. By applying the three-dimensional finite-difference-time-domain (3D-FDTD) method, the sensitivities calculated were S1 = 492 nm/RIU, S2 = 244 nm/RIU, and S3 = 552 nm/RIU, respectively. To the best of our knowledge, this is the first multiplexing design in which each sensor cite features such a high sensitivity simultaneously. PMID:27399712

A geostatistics-informed hierarchical sensitivity analysis method for complex groundwater flow and transport modeling

NASA Astrophysics Data System (ADS)

Dai, Heng; Chen, Xingyuan; Ye, Ming; Song, Xuehang; Zachara, John M.

2017-05-01

Sensitivity analysis is an important tool for development and improvement of mathematical models, especially for complex systems with a high dimension of spatially correlated parameters. Variance-based global sensitivity analysis has gained popularity because it can quantify the relative contribution of uncertainty from different sources. However, its computational cost increases dramatically with the complexity of the considered model and the dimension of model parameters. In this study, we developed a new sensitivity analysis method that integrates the concept of variance-based method with a hierarchical uncertainty quantification framework. Different uncertain inputs are grouped and organized into a multilayer framework based on their characteristics and dependency relationships to reduce the dimensionality of the sensitivity analysis. A set of new sensitivity indices are defined for the grouped inputs using the variance decomposition method. Using this methodology, we identified the most important uncertainty source for a dynamic groundwater flow and solute transport model at the Department of Energy (DOE) Hanford site. The results indicate that boundary conditions and permeability field contribute the most uncertainty to the simulated head field and tracer plume, respectively. The relative contribution from each source varied spatially and temporally. By using a geostatistical approach to reduce the number of realizations needed for the sensitivity analysis, the computational cost of implementing the developed method was reduced to a practically manageable level. The developed sensitivity analysis method is generally applicable to a wide range of hydrologic and environmental problems that deal with high-dimensional spatially distributed input variables.

A Geostatistics-Informed Hierarchical Sensitivity Analysis Method for Complex Groundwater Flow and Transport Modeling

NASA Astrophysics Data System (ADS)

Dai, H.; Chen, X.; Ye, M.; Song, X.; Zachara, J. M.

2017-12-01

Sensitivity analysis is an important tool for development and improvement of mathematical models, especially for complex systems with a high dimension of spatially correlated parameters. Variance-based global sensitivity analysis has gained popularity because it can quantify the relative contribution of uncertainty from different sources. However, its computational cost increases dramatically with the complexity of the considered model and the dimension of model parameters. In this study we developed a new sensitivity analysis method that integrates the concept of variance-based method with a hierarchical uncertainty quantification framework. Different uncertain inputs are grouped and organized into a multi-layer framework based on their characteristics and dependency relationships to reduce the dimensionality of the sensitivity analysis. A set of new sensitivity indices are defined for the grouped inputs using the variance decomposition method. Using this methodology, we identified the most important uncertainty source for a dynamic groundwater flow and solute transport model at the Department of Energy (DOE) Hanford site. The results indicate that boundary conditions and permeability field contribute the most uncertainty to the simulated head field and tracer plume, respectively. The relative contribution from each source varied spatially and temporally. By using a geostatistical approach to reduce the number of realizations needed for the sensitivity analysis, the computational cost of implementing the developed method was reduced to a practically manageable level. The developed sensitivity analysis method is generally applicable to a wide range of hydrologic and environmental problems that deal with high-dimensional spatially-distributed input variables.

Applicability of the two-angle differential method to response measurement of neutron-sensitive devices at the RCNP high-energy neutron facility

NASA Astrophysics Data System (ADS)

Masuda, Akihiko; Matsumoto, Tetsuro; Iwamoto, Yosuke; Hagiwara, Masayuki; Satoh, Daiki; Sato, Tatsuhiko; Iwase, Hiroshi; Yashima, Hiroshi; Nakane, Yoshihiro; Nishiyama, Jun; Shima, Tatsushi; Tamii, Atsushi; Hatanaka, Kichiji; Harano, Hideki; Nakamura, Takashi

2017-03-01

Quasi-monoenergetic high-energy neutron fields induced by 7Li(p,n) reactions are used for the response evaluation of neutron-sensitive devices. The quasi-monoenergetic high-energy field consists of high-energy monoenergetic peak neutrons and unwanted continuum neutrons down to the low-energy region. A two-angle differential method has been developed to compensate for the effect of the continuum neutrons in the response measurements. In this study, the two-angle differential method was demonstrated for Bonner sphere detectors, which are typical examples of moderator-based neutron-sensitive detectors, to investigate the method's applicability and its dependence on detector characteristics. Experiments were performed under 96-387 MeV quasi-monoenergetic high-energy neutron fields at the Research Center for Nuclear Physics (RCNP), Osaka University. The measurement results for large high-density polyethylene (HDPE) sphere detectors agreed well with Monte Carlo calculations, which verified the adequacy of the two-angle differential method. By contrast, discrepancies were observed in the results for small HDPE sphere detectors and metal-induced sphere detectors. The former indicated that detectors that are particularly sensitive to low-energy neutrons may be affected by penetrating neutrons owing to the geometrical features of the RCNP facility. The latter discrepancy could be consistently explained by a problem in the evaluated cross-section data for the metals used in the calculation. Through those discussions, the adequacy of the two-angle differential method was experimentally verified, and practical suggestions were made pertaining to this method.

Validated method for quantification of genetically modified organisms in samples of maize flour.

PubMed

Kunert, Renate; Gach, Johannes S; Vorauer-Uhl, Karola; Engel, Edwin; Katinger, Hermann

2006-02-08

Sensitive and accurate testing for trace amounts of biotechnology-derived DNA from plant material is the prerequisite for detection of 1% or 0.5% genetically modified ingredients in food products or raw materials thereof. Compared to ELISA detection of expressed proteins, real-time PCR (RT-PCR) amplification has easier sample preparation and detection limits are lower. Of the different methods of DNA preparation CTAB method with high flexibility in starting material and generation of sufficient DNA with relevant quality was chosen. Previous RT-PCR data generated with the SYBR green detection method showed that the method is highly sensitive to sample matrices and genomic DNA content influencing the interpretation of results. Therefore, this paper describes a real-time DNA quantification based on the TaqMan probe method, indicating high accuracy and sensitivity with detection limits of lower than 18 copies per sample applicable and comparable to highly purified plasmid standards as well as complex matrices of genomic DNA samples. The results were evaluated with ValiData for homology of variance, linearity, accuracy of the standard curve, and standard deviation.

Addressing Curse of Dimensionality in Sensitivity Analysis: How Can We Handle High-Dimensional Problems?

NASA Astrophysics Data System (ADS)

Safaei, S.; Haghnegahdar, A.; Razavi, S.

2016-12-01

Complex environmental models are now the primary tool to inform decision makers for the current or future management of environmental resources under the climate and environmental changes. These complex models often contain a large number of parameters that need to be determined by a computationally intensive calibration procedure. Sensitivity analysis (SA) is a very useful tool that not only allows for understanding the model behavior, but also helps in reducing the number of calibration parameters by identifying unimportant ones. The issue is that most global sensitivity techniques are highly computationally demanding themselves for generating robust and stable sensitivity metrics over the entire model response surface. Recently, a novel global sensitivity analysis method, Variogram Analysis of Response Surfaces (VARS), is introduced that can efficiently provide a comprehensive assessment of global sensitivity using the Variogram concept. In this work, we aim to evaluate the effectiveness of this highly efficient GSA method in saving computational burden, when applied to systems with extra-large number of input factors ( 100). We use a test function and a hydrological modelling case study to demonstrate the capability of VARS method in reducing problem dimensionality by identifying important vs unimportant input factors.

[Multiplex real-time PCR method for rapid detection of Marburg virus and Ebola virus].

PubMed

Yang, Yu; Bai, Lin; Hu, Kong-Xin; Yang, Zhi-Hong; Hu, Jian-Ping; Wang, Jing

2012-08-01

Marburg virus and Ebola virus are acute infections with high case fatality rates. A rapid, sensitive detection method was established to detect Marburg virus and Ebola virus by multiplex real-time fluorescence quantitative PCR. Designing primers and Taqman probes from highly conserved sequences of Marburg virus and Ebola virus through whole genome sequences alignment, Taqman probes labeled by FAM and Texas Red, the sensitivity of the multiplex real-time quantitative PCR assay was optimized by evaluating the different concentrations of primers and Probes. We have developed a real-time PCR method with the sensitivity of 30.5 copies/microl for Marburg virus positive plasmid and 28.6 copies/microl for Ebola virus positive plasmids, Japanese encephalitis virus, Yellow fever virus, Dengue virus were using to examine the specificity. The Multiplex real-time PCR assays provide a sensitive, reliable and efficient method to detect Marburg virus and Ebola virus simultaneously.

High field CdS detector for infrared radiation

NASA Technical Reports Server (NTRS)

Tyagi, R. C.; Boer, K. W.; Hadley, H. C.; Robertson, J. B.

1972-01-01

New and highly sensitive method of detecting infrared irradiation makes possible solid state infrared detector which is more sensitive near room temperature than usual photoconductive low band gap semiconductor devices. Reconfiguration of high field domains in cadmium sulphide crystals provides basis for discovery.

The PneuCarriage Project: A Multi-Centre Comparative Study to Identify the Best Serotyping Methods for Examining Pneumococcal Carriage in Vaccine Evaluation Studies

PubMed Central

Satzke, Catherine; Dunne, Eileen M.; Porter, Barbara D.; Klugman, Keith P.; Mulholland, E. Kim

2015-01-01

Background The pneumococcus is a diverse pathogen whose primary niche is the nasopharynx. Over 90 different serotypes exist, and nasopharyngeal carriage of multiple serotypes is common. Understanding pneumococcal carriage is essential for evaluating the impact of pneumococcal vaccines. Traditional serotyping methods are cumbersome and insufficient for detecting multiple serotype carriage, and there are few data comparing the new methods that have been developed over the past decade. We established the PneuCarriage project, a large, international multi-centre study dedicated to the identification of the best pneumococcal serotyping methods for carriage studies. Methods and Findings Reference sample sets were distributed to 15 research groups for blinded testing. Twenty pneumococcal serotyping methods were used to test 81 laboratory-prepared (spiked) samples. The five top-performing methods were used to test 260 nasopharyngeal (field) samples collected from children in six high-burden countries. Sensitivity and positive predictive value (PPV) were determined for the test methods and the reference method (traditional serotyping of >100 colonies from each sample). For the alternate serotyping methods, the overall sensitivity ranged from 1% to 99% (reference method 98%), and PPV from 8% to 100% (reference method 100%), when testing the spiked samples. Fifteen methods had ≥70% sensitivity to detect the dominant (major) serotype, whilst only eight methods had ≥70% sensitivity to detect minor serotypes. For the field samples, the overall sensitivity ranged from 74.2% to 95.8% (reference method 93.8%), and PPV from 82.2% to 96.4% (reference method 99.6%). The microarray had the highest sensitivity (95.8%) and high PPV (93.7%). The major limitation of this study is that not all of the available alternative serotyping methods were included. Conclusions Most methods were able to detect the dominant serotype in a sample, but many performed poorly in detecting the minor serotype populations. Microarray with a culture amplification step was the top-performing method. Results from this comprehensive evaluation will inform future vaccine evaluation and impact studies, particularly in low-income settings, where pneumococcal disease burden remains high. PMID:26575033

Engineered nanoconstructs for the multiplexed and sensitive detection of high-risk pathogens

NASA Astrophysics Data System (ADS)

Seo, Youngmin; Kim, Ji-Eun; Jeong, Yoon; Lee, Kwan Hong; Hwang, Jangsun; Hong, Jongwook; Park, Hansoo; Choi, Jonghoon

2016-01-01

Many countries categorize the causative agents of severe infectious diseases as high-risk pathogens. Given their extreme infectivity and potential to be used as biological weapons, a rapid and sensitive method for detection of high-risk pathogens (e.g., Bacillus anthracis, Francisella tularensis, Yersinia pestis, and Vaccinia virus) is highly desirable. Here, we report the construction of a novel detection platform comprising two units: (1) magnetic beads separately conjugated with multiple capturing antibodies against four different high-risk pathogens for simple and rapid isolation, and (2) genetically engineered apoferritin nanoparticles conjugated with multiple quantum dots and detection antibodies against four different high-risk pathogens for signal amplification. For each high-risk pathogen, we demonstrated at least 10-fold increase in sensitivity compared to traditional lateral flow devices that utilize enzyme-based detection methods. Multiplexed detection of high-risk pathogens in a sample was also successful by using the nanoconstructs harboring the dye molecules with fluorescence at different wavelengths. We ultimately envision the use of this novel nanoprobe detection platform in future applications that require highly sensitive on-site detection of high-risk pathogens.

The PneuCarriage Project: A Multi-Centre Comparative Study to Identify the Best Serotyping Methods for Examining Pneumococcal Carriage in Vaccine Evaluation Studies.

PubMed

Satzke, Catherine; Dunne, Eileen M; Porter, Barbara D; Klugman, Keith P; Mulholland, E Kim

2015-11-01

The pneumococcus is a diverse pathogen whose primary niche is the nasopharynx. Over 90 different serotypes exist, and nasopharyngeal carriage of multiple serotypes is common. Understanding pneumococcal carriage is essential for evaluating the impact of pneumococcal vaccines. Traditional serotyping methods are cumbersome and insufficient for detecting multiple serotype carriage, and there are few data comparing the new methods that have been developed over the past decade. We established the PneuCarriage project, a large, international multi-centre study dedicated to the identification of the best pneumococcal serotyping methods for carriage studies. Reference sample sets were distributed to 15 research groups for blinded testing. Twenty pneumococcal serotyping methods were used to test 81 laboratory-prepared (spiked) samples. The five top-performing methods were used to test 260 nasopharyngeal (field) samples collected from children in six high-burden countries. Sensitivity and positive predictive value (PPV) were determined for the test methods and the reference method (traditional serotyping of >100 colonies from each sample). For the alternate serotyping methods, the overall sensitivity ranged from 1% to 99% (reference method 98%), and PPV from 8% to 100% (reference method 100%), when testing the spiked samples. Fifteen methods had ≥70% sensitivity to detect the dominant (major) serotype, whilst only eight methods had ≥70% sensitivity to detect minor serotypes. For the field samples, the overall sensitivity ranged from 74.2% to 95.8% (reference method 93.8%), and PPV from 82.2% to 96.4% (reference method 99.6%). The microarray had the highest sensitivity (95.8%) and high PPV (93.7%). The major limitation of this study is that not all of the available alternative serotyping methods were included. Most methods were able to detect the dominant serotype in a sample, but many performed poorly in detecting the minor serotype populations. Microarray with a culture amplification step was the top-performing method. Results from this comprehensive evaluation will inform future vaccine evaluation and impact studies, particularly in low-income settings, where pneumococcal disease burden remains high.

Multiplexed highly sensitive detections of cancer biomarkers in thermal space using encapsulated phase change nanoparticles

NASA Astrophysics Data System (ADS)

Ma, Liyuan; Hong, Yan; Ma, Zeyu; Kaittanis, Charalambos; Perez, J. Manuel; Su, Ming

2009-07-01

We describe a multiplexed highly sensitive method to detect cancer biomarkers using silica encapsulated phase change nanoparticles as thermal barcodes. During phase changes, nanoparticles absorb heat energy without much temperature rise and show sharp melting peaks (0.6 °C). A series of phase change nanoparticles of metals or alloys can be synthesized in such a way that they melt between 100 and 700 °C, thus the multiplicity could reach 1000. The method has high sensitivity (8 nM) that can be enhanced using materials with large latent heat, nanoparticles with large diameter, or reducing the grafting density of biomolecules on nanoparticles.

Highly sensitive catalytic spectrophotometric determination of ruthenium

NASA Astrophysics Data System (ADS)

Naik, Radhey M.; Srivastava, Abhishek; Prasad, Surendra

2008-01-01

A new and highly sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III) has been established based on its catalytic effect on the oxidation of L-phenylalanine ( L-Pheala) by KMnO 4 in highly alkaline medium. The reaction has been followed spectrophotometrically by measuring the decrease in the absorbance at 526 nm. The proposed CKM is based on the fixed time procedure under optimum reaction conditions. It relies on the linear relationship where the change in the absorbance (Δ At) versus added Ru(III) amounts in the range of 0.101-2.526 ng ml -1 is plotted. Under the optimum conditions, the sensitivity of the proposed method, i.e. the limit of detection corresponding to 5 min is 0.08 ng ml -1, and decreases with increased time of analysis. The method is featured with good accuracy and reproducibility for ruthenium(III) determination. The ruthenium(III) has also been determined in presence of several interfering and non-interfering cations, anions and polyaminocarboxylates. No foreign ions interfered in the determination ruthenium(III) up to 20-fold higher concentration of foreign ions. In addition to standard solutions analysis, this method was successfully applied for the quantitative determination of ruthenium(III) in drinking water samples. The method is highly sensitive, selective and very stable. A review of recently published catalytic spectrophotometric methods for the determination of ruthenium(III) has also been presented for comparison.

Electrooptic modulation methods for high sensitivity tunable diode laser spectroscopy

NASA Technical Reports Server (NTRS)

Glenar, David A.; Jennings, Donald E.; Nadler, Shacher

1990-01-01

A CdTe phase modulator and low power RF sources have been used with Pb-salt tunable diode lasers operating near 8 microns to generate optical sidebands for high sensitivity absorption spectroscopy. Sweep averaged, first-derivative sample spectra of CH4 were acquired by wideband phase sensitive detection of the electrooptically (EO) generated carrier-sideband beat signal. EO generated beat signals were also used to frequency lock the TDL to spectral lines. This eliminates low frequency diode jitter, and avoids the excess laser linewidth broadening that accompanies TDL current modulation frequency locking methods.

Combining isothermal rolling circle amplification and electrochemiluminescence for highly sensitive point mutation detection

NASA Astrophysics Data System (ADS)

Su, Qiang; Zhou, Xiaoming

2008-12-01

Many pathogenic and genetic diseases are associated with changes in the sequence of particular genes. We describe here a rapid and highly efficient assay for the detection of point mutation. This method is a combination of isothermal rolling circle amplification (RCA) and high sensitive electrochemluminescence (ECL) detection. In the design, a circular template generated by ligation upon the recognition of a point mutation on DNA targets was amplified isothermally by the Phi29 polymerase using a biotinylated primer. The elongation products were hybridized with tris (bipyridine) ruthenium (TBR)-tagged probes and detected in a magnetic bead based ECL platform, indicating the mutation occurrence. P53 was chosen as a model for the identification of this method. The method allowed sensitive determination of the P53 mutation from wild-type and mutant samples. The main advantage of RCA-ECL is that it can be performed under isothermal conditions and avoids the generation of false-positive results. Furthermore, ECL provides a faster, more sensitive, and economical option to currently available electrophoresis-based methods.

Pseudotargeted MS Method for the Sensitive Analysis of Protein Phosphorylation in Protein Complexes.

PubMed

Lyu, Jiawen; Wang, Yan; Mao, Jiawei; Yao, Yating; Wang, Shujuan; Zheng, Yong; Ye, Mingliang

2018-05-15

In this study, we presented an enrichment-free approach for the sensitive analysis of protein phosphorylation in minute amounts of samples, such as purified protein complexes. This method takes advantage of the high sensitivity of parallel reaction monitoring (PRM). Specifically, low confident phosphopeptides identified from the data-dependent acquisition (DDA) data set were used to build a pseudotargeted list for PRM analysis to allow the identification of additional phosphopeptides with high confidence. The development of this targeted approach is very easy as the same sample and the same LC-system were used for the discovery and the targeted analysis phases. No sample fractionation or enrichment was required for the discovery phase which allowed this method to analyze minute amount of sample. We applied this pseudotargeted MS method to quantitatively examine phosphopeptides in affinity purified endogenous Shc1 protein complexes at four temporal stages of EGF signaling and identified 82 phospho-sites. To our knowledge, this is the highest number of phospho-sites identified from the protein complexes. This pseudotargeted MS method is highly sensitive in the identification of low abundance phosphopeptides and could be a powerful tool to study phosphorylation-regulated assembly of protein complex.

High Temperature and High Sensitive NOx Gas Sensor with Hetero-Junction Structure using Laser Ablation Method

NASA Astrophysics Data System (ADS)

Gao, Wei; Shi, Liqin; Hasegawa, Yuki; Katsube, Teruaki

In order to develop a high temperature (200°C˜400°C) and high sensitive NOx gas sensor, we developed a new structure of SiC-based hetero-junction device Pt/SnO2/SiC/Ni, Pt/In2O3/SiC/Ni and Pt/WO3/SiC/Ni using a laser ablation method for the preparation of both metal (Pt) electrode and metal-oxide film. It was found that Pt/In2O3/SiC/Ni sensor shows higher sensitivity to NO2 gas compared with the Pt/SnO2/SiC/Ni and Pt/WO3/SiC/Ni sensor, whereas the Pt/WO3/SiC/Ni sensor had better sensitivity to NO gas. These results suggest that selective detection of NO and NO2 gases may be obtained by choosing different metal oxide films.

Highly Sensitive GMO Detection Using Real-Time PCR with a Large Amount of DNA Template: Single-Laboratory Validation.

PubMed

Mano, Junichi; Hatano, Shuko; Nagatomi, Yasuaki; Futo, Satoshi; Takabatake, Reona; Kitta, Kazumi

2018-03-01

Current genetically modified organism (GMO) detection methods allow for sensitive detection. However, a further increase in sensitivity will enable more efficient testing for large grain samples and reliable testing for processed foods. In this study, we investigated real-time PCR-based GMO detection methods using a large amount of DNA template. We selected target sequences that are commonly introduced into many kinds of GM crops, i.e., 35S promoter and nopaline synthase (NOS) terminator. This makes the newly developed method applicable to a wide range of GMOs, including some unauthorized ones. The estimated LOD of the new method was 0.005% of GM maize events; to the best of our knowledge, this method is the most sensitive among the GM maize detection methods for which the LOD was evaluated in terms of GMO content. A 10-fold increase in the DNA amount as compared with the amount used under common testing conditions gave an approximately 10-fold reduction in the LOD without PCR inhibition. Our method is applicable to various analytical samples, including processed foods. The use of other primers and fluorescence probes would permit highly sensitive detection of various recombinant DNA sequences besides the 35S promoter and NOS terminator.

Highly sensitive chemiluminescent point mutation detection by circular strand-displacement amplification reaction.

PubMed

Shi, Chao; Ge, Yujie; Gu, Hongxi; Ma, Cuiping

2011-08-15

Single nucleotide polymorphism (SNP) genotyping is attracting extensive attentions owing to its direct connections with human diseases including cancers. Here, we have developed a highly sensitive chemiluminescence biosensor based on circular strand-displacement amplification and the separation by magnetic beads reducing the background signal for point mutation detection at room temperature. This method took advantage of both the T4 DNA ligase recognizing single-base mismatch with high selectivity and the strand-displacement reaction of polymerase to perform signal amplification. The detection limit of this method was 1.3 × 10(-16)M, which showed better sensitivity than that of most of those reported detection methods of SNP. Additionally, the magnetic beads as carrier of immobility was not only to reduce the background signal, but also may have potential apply in high through-put screening of SNP detection in human genome. Copyright © 2011 Elsevier B.V. All rights reserved.

Sensitivity of diagnostic methods for Mansonella ozzardi microfilariae detection in the Brazilian Amazon Region

PubMed Central

Medeiros, Jansen Fernandes; Fontes, Gilberto; do Nascimento, Vilma Lopes; Rodrigues, Moreno; Cohen, Jacob; de Andrade, Edmar Vaz; Pessoa, Felipe Arley Costa; Martins, Marilaine

2018-01-01

BACKGROUND The human filarial worm Mansonella ozzardi is highly endemic in the large tributaries of the Amazon River. This infection is still highly neglected and can be falsely negative when microfilariae levels are low. OBJECTIVES This study investigated the frequency of individuals with M. ozzardi in riverine communities in Coari municipality, Brazilian Amazon. METHODS Different diagnostic methods including polymerase chain reaction (PCR), blood polycarbonate membrane filtration (PCMF), Knott's method (Knott), digital thick blood smears (DTBS) and venous thick blood smears (VTBS) were used to compare sensitivity and specificity among the methods. Data were analysed using PCMF and Bayesian latent class models (BLCM) as the gold standard. We used BLCM to calculate the prevalence of mansonelliasis based on the results of five diagnostic methods. FINDINGS The prevalence of mansonelliasis was 35.4% by PCMF and 30.1% by BLCM. PCR and Knott methods both possessed high sensitivity. Sensitivity relative to PCMF was 98.5% [95% confidence interval (CI): 92.0 - 99.7] for PCR and 83.5% (95% CI: 72.9 - 90.5) for Knott. Sensitivity derived by BLCM was 100% (95% CI 93.7 - 100) for PCMF, 100% (95% CI: 93.7 - 100) for PCR and 98.3% (95% CI: 90.6 - 99.9) for Knott. The odds ratio of being diagnosed as microfilaremic increased with age but did not differ between genders. Microfilariae loads were higher in subjects aged 30 - 45 and 45 - 60 years. MAIN CONCLUSIONS PCMF and PCR were the best methods to assess the prevalence of mansonelliasis in our samples. As such, using these methods could lead to higher prevalence of mansonelliasis in this region than the most commonly used method (i.e., thick blood smears). PMID:29412356

Piezoresistive method for a laser induced shock wave detection on solids

NASA Astrophysics Data System (ADS)

Gonzalez-Romero, R.; Garcia-Torales, G.; Gomez Rosas, G.; Strojnik, M.

2017-08-01

A laser shock wave is a mechanical high-pressure impulse with a duration of a few nanoseconds induced by a high power laser pulse. We performed wave pressure measurements in order to build and check mathematical models. They are used for wave applications in material science, health, and defense, to list a few. Piezoresistive methods have been shown to be highly sensitive, linear, and highly appropriate for practical implementation, compared with piezoelectric methods employed in shock wave pressure measurements. In this work, we develop a novel method to obtain the sensitivity of a piezoresistive measurement system. The results shows that it is possible to use a mechanical method to measure pressure of a laser induced shock wave in nanosecond range. Experimental pressure measurements are presented.

A fluorescence high throughput screening method for the detection of reactive electrophiles as potential skin sensitizers.

PubMed

Avonto, Cristina; Chittiboyina, Amar G; Rua, Diego; Khan, Ikhlas A

2015-12-01

Skin sensitization is an important toxicological end-point in the risk assessment of chemical allergens. Because of the complexity of the biological mechanisms associated with skin sensitization, integrated approaches combining different chemical, biological and in silico methods are recommended to replace conventional animal tests. Chemical methods are intended to characterize the potential of a sensitizer to induce earlier molecular initiating events. The presence of an electrophilic mechanistic domain is considered one of the essential chemical features to covalently bind to the biological target and induce further haptenation processes. Current in chemico assays rely on the quantification of unreacted model nucleophiles after incubation with the candidate sensitizer. In the current study, a new fluorescence-based method, 'HTS-DCYA assay', is proposed. The assay aims at the identification of reactive electrophiles based on their chemical reactivity toward a model fluorescent thiol. The reaction workflow enabled the development of a High Throughput Screening (HTS) method to directly quantify the reaction adducts. The reaction conditions have been optimized to minimize solubility issues, oxidative side reactions and increase the throughput of the assay while minimizing the reaction time, which are common issues with existing methods. Thirty-six chemicals previously classified with LLNA, DPRA or KeratinoSens™ were tested as a proof of concept. Preliminary results gave an estimated 82% accuracy, 78% sensitivity, 90% specificity, comparable to other in chemico methods such as Cys-DPRA. In addition to validated chemicals, six natural products were analyzed and a prediction of their sensitization potential is presented for the first time. Copyright © 2015 Elsevier Inc. All rights reserved.

Sensitivity of diagnostic methods for Mansonella ozzardi microfilariae detection in the Brazilian Amazon Region.

PubMed

Medeiros, Jansen Fernandes; Fontes, Gilberto; Nascimento, Vilma Lopes do; Rodrigues, Moreno; Cohen, Jacob; Andrade, Edmar Vaz de; Pessoa, Felipe Arley Costa; Martins, Marilaine

2018-03-01

The human filarial worm Mansonella ozzardi is highly endemic in the large tributaries of the Amazon River. This infection is still highly neglected and can be falsely negative when microfilariae levels are low. This study investigated the frequency of individuals with M. ozzardi in riverine communities in Coari municipality, Brazilian Amazon. Different diagnostic methods including polymerase chain reaction (PCR), blood polycarbonate membrane filtration (PCMF), Knott's method (Knott), digital thick blood smears (DTBS) and venous thick blood smears (VTBS) were used to compare sensitivity and specificity among the methods. Data were analysed using PCMF and Bayesian latent class models (BLCM) as the gold standard. We used BLCM to calculate the prevalence of mansonelliasis based on the results of five diagnostic methods. The prevalence of mansonelliasis was 35.4% by PCMF and 30.1% by BLCM. PCR and Knott methods both possessed high sensitivity. Sensitivity relative to PCMF was 98.5% [95% confidence interval (CI): 92.0 - 99.7] for PCR and 83.5% (95% CI: 72.9 - 90.5) for Knott. Sensitivity derived by BLCM was 100% (95% CI 93.7 - 100) for PCMF, 100% (95% CI: 93.7 - 100) for PCR and 98.3% (95% CI: 90.6 - 99.9) for Knott. The odds ratio of being diagnosed as microfilaremic increased with age but did not differ between genders. Microfilariae loads were higher in subjects aged 30 - 45 and 45 - 60 years. PCMF and PCR were the best methods to assess the prevalence of mansonelliasis in our samples. As such, using these methods could lead to higher prevalence of mansonelliasis in this region than the most commonly used method (i.e., thick blood smears).

Atomic-resolution transmission electron microscopy of electron beam–sensitive crystalline materials

NASA Astrophysics Data System (ADS)

Zhang, Daliang; Zhu, Yihan; Liu, Lingmei; Ying, Xiangrong; Hsiung, Chia-En; Sougrat, Rachid; Li, Kun; Han, Yu

2018-02-01

High-resolution imaging of electron beam–sensitive materials is one of the most difficult applications of transmission electron microscopy (TEM). The challenges are manifold, including the acquisition of images with extremely low beam doses, the time-constrained search for crystal zone axes, the precise image alignment, and the accurate determination of the defocus value. We develop a suite of methods to fulfill these requirements and acquire atomic-resolution TEM images of several metal organic frameworks that are generally recognized as highly sensitive to electron beams. The high image resolution allows us to identify individual metal atomic columns, various types of surface termination, and benzene rings in the organic linkers. We also apply our methods to other electron beam–sensitive materials, including the organic-inorganic hybrid perovskite CH3NH3PbBr3.

Low-Cost and Rapid Fabrication of Metallic Nanostructures for Sensitive Biosensors Using Hot-Embossing and Dielectric-Heating Nanoimprint Methods.

PubMed

Lee, Kuang-Li; Wu, Tsung-Yeh; Hsu, Hsuan-Yeh; Yang, Sen-Yeu; Wei, Pei-Kuen

2017-07-02

We propose two approaches-hot-embossing and dielectric-heating nanoimprinting methods-for low-cost and rapid fabrication of periodic nanostructures. Each nanofabrication process for the imprinted plastic nanostructures is completed within several seconds without the use of release agents and epoxy. Low-cost, large-area, and highly sensitive aluminum nanostructures on A4 size plastic films are fabricated by evaporating aluminum film on hot-embossing nanostructures. The narrowest bandwidth of the Fano resonance is only 2.7 nm in the visible light region. The periodic aluminum nanostructure achieves a figure of merit of 150, and an intensity sensitivity of 29,345%/RIU (refractive index unit). The rapid fabrication is also achieved by using radio-frequency (RF) sensitive plastic films and a commercial RF welding machine. The dielectric-heating, using RF power, takes advantage of the rapid heating/cooling process and lower electric power consumption. The fabricated capped aluminum nanoslit array has a 5 nm Fano linewidth and 490.46 nm/RIU wavelength sensitivity. The biosensing capabilities of the metallic nanostructures are further verified by measuring antigen-antibody interactions using bovine serum albumin (BSA) and anti-BSA. These rapid and high-throughput fabrication methods can benefit low-cost, highly sensitive biosensors and other sensing applications.

Towards high-throughput molecular detection of Plasmodium: new approaches and molecular markers

PubMed Central

Steenkeste, Nicolas; Incardona, Sandra; Chy, Sophy; Duval, Linda; Ekala, Marie-Thérèse; Lim, Pharath; Hewitt, Sean; Sochantha, Tho; Socheat, Doung; Rogier, Christophe; Mercereau-Puijalon, Odile; Fandeur, Thierry; Ariey, Frédéric

2009-01-01

Background Several strategies are currently deployed in many countries in the tropics to strengthen malaria control toward malaria elimination. To measure the impact of any intervention, there is a need to detect malaria properly. Mostly, decisions still rely on microscopy diagnosis. But sensitive diagnosis tools enabling to deal with a large number of samples are needed. The molecular detection approach offers a much higher sensitivity, and the flexibility to be automated and upgraded. Methods Two new molecular methods were developed: dot18S, a Plasmodium-specific nested PCR based on the 18S rRNA gene followed by dot-blot detection of species by using species-specific probes and CYTB, a Plasmodium-specific nested PCR based on cytochrome b gene followed by species detection using SNP analysis. The results were compared to those obtained with microscopic examination and the "standard" 18S rRNA gene based nested PCR using species specific primers. 337 samples were diagnosed. Results Compared to the microscopy the three molecular methods were more sensitive, greatly increasing the estimated prevalence of Plasmodium infection, including P. malariae and P. ovale. A high rate of mixed infections was uncovered with about one third of the villagers infected with more than one malaria parasite species. Dot18S and CYTB sensitivity outranged the "standard" nested PCR method, CYTB being the most sensitive. As a consequence, compared to the "standard" nested PCR method for the detection of Plasmodium spp., the sensitivity of dot18S and CYTB was respectively 95.3% and 97.3%. Consistent detection of Plasmodium spp. by the three molecular methods was obtained for 83% of tested isolates. Contradictory results were mostly related to detection of Plasmodium malariae and Plasmodium ovale in mixed infections, due to an "all-or-none" detection effect at low-level parasitaemia. Conclusion A large reservoir of asymptomatic infections was uncovered using the molecular methods. Dot18S and CYTB, the new methods reported herein are highly sensitive, allow parasite DNA extraction as well as genus- and species-specific diagnosis of several hundreds of samples, and are amenable to high-throughput scaling up for larger sample sizes. Such methods provide novel information on malaria prevalence and epidemiology and are suited for active malaria detection. The usefulness of such sensitive malaria diagnosis tools, especially in low endemic areas where eradication plans are now on-going, is discussed in this paper. PMID:19402894

A fluorescence high throughput screening method for the detection of reactive electrophiles as potential skin sensitizers

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

Avonto, Cristina; Chittiboyina, Amar G.; Rua, Diego

2015-12-01

Skin sensitization is an important toxicological end-point in the risk assessment of chemical allergens. Because of the complexity of the biological mechanisms associated with skin sensitization, integrated approaches combining different chemical, biological and in silico methods are recommended to replace conventional animal tests. Chemical methods are intended to characterize the potential of a sensitizer to induce earlier molecular initiating events. The presence of an electrophilic mechanistic domain is considered one of the essential chemical features to covalently bind to the biological target and induce further haptenation processes. Current in chemico assays rely on the quantification of unreacted model nucleophiles aftermore » incubation with the candidate sensitizer. In the current study, a new fluorescence-based method, ‘HTS-DCYA assay’, is proposed. The assay aims at the identification of reactive electrophiles based on their chemical reactivity toward a model fluorescent thiol. The reaction workflow enabled the development of a High Throughput Screening (HTS) method to directly quantify the reaction adducts. The reaction conditions have been optimized to minimize solubility issues, oxidative side reactions and increase the throughput of the assay while minimizing the reaction time, which are common issues with existing methods. Thirty-six chemicals previously classified with LLNA, DPRA or KeratinoSens™ were tested as a proof of concept. Preliminary results gave an estimated 82% accuracy, 78% sensitivity, 90% specificity, comparable to other in chemico methods such as Cys-DPRA. In addition to validated chemicals, six natural products were analyzed and a prediction of their sensitization potential is presented for the first time. - Highlights: • A novel fluorescence-based method to detect electrophilic sensitizers is proposed. • A model fluorescent thiol was used to directly quantify the reaction products. • A discussion of the reaction workflow and critical parameters is presented. • The method could provide a useful tool to complement existing chemical assays.« less

Determination of boldine in plasma by high-performance liquid chromatography.

PubMed

Speisky, H; Cassels, B K; Nieto, S; Valenzuela, A; Nuñez-Vergara, L J

1993-02-26

A sensitive method for the determination of boldine in blood plasma is described. The procedure involves a direct pH-buffered chloroform extraction of boldine from blood plasma, followed by its assay under isocratic conditions by HPLC with UV detection. The extraction recovery is excellent, and sensitivity and precision of the method are very high, when applied to plasma samples containing pharmacologically relevant concentrations of boldine.

In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla.

PubMed

Li, Mingyan; Jin, Jin; Zuo, Zhentao; Liu, Feng; Trakic, Adnan; Weber, Ewald; Zhuo, Yan; Xue, Rong; Crozier, Stuart

2015-03-01

Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1(-)) become distinct at various angular positions. Therefore, sensitivity maps at other angular positions cannot be obtained by numerically rotating the acquired ones. In this work, a novel sensitivity estimation method for the RRFCA was developed and validated with human brain imaging. This method employed a library database and registration techniques to estimate coil sensitivity at an arbitrary angular position. The estimated sensitivity maps were then compared to the acquired sensitivity maps. The results indicate that the proposed method is capable of accurately estimating both magnitude and phase of sensitivity at an arbitrary angular position, which enables us to employ the rotating-SENSE algorithm to accelerate acquisition and reconstruct image. Compared to a stationary coil array with the same number of coil elements, the RRFCA was able to reconstruct images with better quality at a high reduction factor. It is hoped that the proposed rotation-dependent sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI. Copyright © 2014 Elsevier Inc. All rights reserved.

In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

NASA Astrophysics Data System (ADS)

Li, Mingyan; Jin, Jin; Zuo, Zhentao; Liu, Feng; Trakic, Adnan; Weber, Ewald; Zhuo, Yan; Xue, Rong; Crozier, Stuart

2015-03-01

Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1-) become distinct at various angular positions. Therefore, sensitivity maps at other angular positions cannot be obtained by numerically rotating the acquired ones. In this work, a novel sensitivity estimation method for the RRFCA was developed and validated with human brain imaging. This method employed a library database and registration techniques to estimate coil sensitivity at an arbitrary angular position. The estimated sensitivity maps were then compared to the acquired sensitivity maps. The results indicate that the proposed method is capable of accurately estimating both magnitude and phase of sensitivity at an arbitrary angular position, which enables us to employ the rotating-SENSE algorithm to accelerate acquisition and reconstruct image. Compared to a stationary coil array with the same number of coil elements, the RRFCA was able to reconstruct images with better quality at a high reduction factor. It is hoped that the proposed rotation-dependent sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI.

Aptamer-Functionalized Fluorescent Silica Nanoparticles for Highly Sensitive Detection of Leukemia Cells

NASA Astrophysics Data System (ADS)

Tan, Juntao; Yang, Nuo; Hu, Zixi; Su, Jing; Zhong, Jianhong; Yang, Yang; Yu, Yating; Zhu, Jianmeng; Xue, Dabin; Huang, Yingying; Lai, Zongqiang; Huang, Yong; Lu, Xiaoling; Zhao, Yongxiang

2016-06-01

A simple, highly sensitive method to detect leukemia cells has been developed based on aptamer-modified fluorescent silica nanoparticles (FSNPs). In this strategy, the amine-labeled Sgc8 aptamer was conjugated to carboxyl-modified FSNPs via amide coupling between amino and carboxyl groups. Sensitivity and specificity of Sgc8-FSNPs were assessed using flow cytometry and fluorescence microscopy. These results showed that Sgc8-FSNPs detected leukemia cells with high sensitivity and specificity. Aptamer-modified FSNPs hold promise for sensitive and specific detection of leukemia cells. Changing the aptamer may allow the FSNPs to detect other types of cancer cells.

Serine Protease Zymography: Low-Cost, Rapid, and Highly Sensitive RAMA Casein Zymography.

PubMed

Yasumitsu, Hidetaro

2017-01-01

To detect serine protease activity by zymography, casein and CBB stain have been used as a substrate and a detection procedure, respectively. Casein zymography has been using substrate concentration at 1 mg/mL and employing conventional CBB stain. Although ordinary casein zymography provides reproducible results, it has several disadvantages including time-consuming and relative low sensitivity. Improved casein zymography, RAMA casein zymography, is rapid and highly sensitive. RAMA casein zymography completes the detection process within 1 h after incubation and increases the sensitivity at least by tenfold. In addition to serine protease, the method also detects metalloprotease 7 (MMP7, Matrilysin) with high sensitivity.

Methylation Sensitive Amplification Polymorphism Sequencing (MSAP-Seq)-A Method for High-Throughput Analysis of Differentially Methylated CCGG Sites in Plants with Large Genomes.

PubMed

Chwialkowska, Karolina; Korotko, Urszula; Kosinska, Joanna; Szarejko, Iwona; Kwasniewski, Miroslaw

2017-01-01

Epigenetic mechanisms, including histone modifications and DNA methylation, mutually regulate chromatin structure, maintain genome integrity, and affect gene expression and transposon mobility. Variations in DNA methylation within plant populations, as well as methylation in response to internal and external factors, are of increasing interest, especially in the crop research field. Methylation Sensitive Amplification Polymorphism (MSAP) is one of the most commonly used methods for assessing DNA methylation changes in plants. This method involves gel-based visualization of PCR fragments from selectively amplified DNA that are cleaved using methylation-sensitive restriction enzymes. In this study, we developed and validated a new method based on the conventional MSAP approach called Methylation Sensitive Amplification Polymorphism Sequencing (MSAP-Seq). We improved the MSAP-based approach by replacing the conventional separation of amplicons on polyacrylamide gels with direct, high-throughput sequencing using Next Generation Sequencing (NGS) and automated data analysis. MSAP-Seq allows for global sequence-based identification of changes in DNA methylation. This technique was validated in Hordeum vulgare . However, MSAP-Seq can be straightforwardly implemented in different plant species, including crops with large, complex and highly repetitive genomes. The incorporation of high-throughput sequencing into MSAP-Seq enables parallel and direct analysis of DNA methylation in hundreds of thousands of sites across the genome. MSAP-Seq provides direct genomic localization of changes and enables quantitative evaluation. We have shown that the MSAP-Seq method specifically targets gene-containing regions and that a single analysis can cover three-quarters of all genes in large genomes. Moreover, MSAP-Seq's simplicity, cost effectiveness, and high-multiplexing capability make this method highly affordable. Therefore, MSAP-Seq can be used for DNA methylation analysis in crop plants with large and complex genomes.

Methylation Sensitive Amplification Polymorphism Sequencing (MSAP-Seq)—A Method for High-Throughput Analysis of Differentially Methylated CCGG Sites in Plants with Large Genomes

PubMed Central

Chwialkowska, Karolina; Korotko, Urszula; Kosinska, Joanna; Szarejko, Iwona; Kwasniewski, Miroslaw

2017-01-01

Epigenetic mechanisms, including histone modifications and DNA methylation, mutually regulate chromatin structure, maintain genome integrity, and affect gene expression and transposon mobility. Variations in DNA methylation within plant populations, as well as methylation in response to internal and external factors, are of increasing interest, especially in the crop research field. Methylation Sensitive Amplification Polymorphism (MSAP) is one of the most commonly used methods for assessing DNA methylation changes in plants. This method involves gel-based visualization of PCR fragments from selectively amplified DNA that are cleaved using methylation-sensitive restriction enzymes. In this study, we developed and validated a new method based on the conventional MSAP approach called Methylation Sensitive Amplification Polymorphism Sequencing (MSAP-Seq). We improved the MSAP-based approach by replacing the conventional separation of amplicons on polyacrylamide gels with direct, high-throughput sequencing using Next Generation Sequencing (NGS) and automated data analysis. MSAP-Seq allows for global sequence-based identification of changes in DNA methylation. This technique was validated in Hordeum vulgare. However, MSAP-Seq can be straightforwardly implemented in different plant species, including crops with large, complex and highly repetitive genomes. The incorporation of high-throughput sequencing into MSAP-Seq enables parallel and direct analysis of DNA methylation in hundreds of thousands of sites across the genome. MSAP-Seq provides direct genomic localization of changes and enables quantitative evaluation. We have shown that the MSAP-Seq method specifically targets gene-containing regions and that a single analysis can cover three-quarters of all genes in large genomes. Moreover, MSAP-Seq's simplicity, cost effectiveness, and high-multiplexing capability make this method highly affordable. Therefore, MSAP-Seq can be used for DNA methylation analysis in crop plants with large and complex genomes. PMID:29250096

Diagnostic sensitivity and specificity of a participatory disease surveillance method for highly pathogenic avian influenza in household chicken flocks in Indonesia.

PubMed

Robyn, M; Priyono, W B; Kim, L M; Brum, E

2012-06-01

A study was conducted to assess the diagnostic sensitivity and specificity of a disease surveillance method for diagnosis of highly pathogenic avian influenza (HPAI) outbreaks in household chicken flocks used by participatory disease surveillance (PDS) teams in Yogyakarta Province, Indonesia. The Government of Indonesia, in partnership with the Food and Agriculture Organization of the United Nations, has implemented a PDS method for the detection of HPAI outbreaks in poultry since 2006. The PDS method in Indonesia utilizes both a clinical case definition (CD) and the result of a commercial rapid antigen test kit Yogyakarta 55611, to diagnose HPAI outbreaks, primarily in backyard chicken flocks. The following diagnostic sensitivities and specificities were obtained relative to real-time reverse transcription-PCR as the gold standard diagnostic test: 1) 89% sensitivity (CI95: 75%-97%) and 96% specificity (CI95: 89%-99%) for the PDS CD alone; 2) 86% sensitivity (CI95: 71%-95%) and 99% specificity (CI95: 94%-100%) for the rapid antigen test alone; and 3) 84% sensitivity (CI95: 68%-94%) and 100% specificity (CI95: 96%-100%) for the PDS CD result combined with the rapid antigen test result. Based on these results, HPAI outbreaks in extensively raised household chickens can be diagnosed with sufficient sensitivity and specificity using the PDS method as implemented in Indonesia. Subject to further field evaluation, data from this study suggest that the diagnostic sensitivity of the PDS method may be improved by expanding the PDS CD to include more possible clinical presentations of HPAI and by increasing the number of rapid antigen tests to three different birds with HPAI-compatible signs of same flock.

Quantification of trans-1,4-polyisoprene in Eucommia ulmoides by fourier transform infrared spectroscopy and pyrolysis-gas chromatography/mass spectrometry.

PubMed

Takeno, Shinya; Bamba, Takeshi; Nakazawa, Yoshihisa; Fukusaki, Eiichiro; Okazawa, Atsushi; Kobayashi, Akio

2008-04-01

Commercial development of trans-1,4-polyisoprene from Eucommia ulmoides Oliver (EU-rubber) requires specific knowledge on selection of high-rubber-content lines and establishment of agronomic cultivation methods for achieving maximum EU-rubber yield. The development can be facilitated by high-throughput and highly sensitive analytical techniques for EU-rubber extraction and quantification. In this paper, we described an efficient EU-rubber extraction method, and validated that the accuracy was equivalent to that of the conventional Soxhlet extraction method. We also described a highly sensitive quantification method for EU-rubber by Fourier transform infrared spectroscopy (FT-IR) and pyrolysis-gas chromatography/mass spectrometry (PyGC/MS). We successfully applied the extraction/quantification method for study of seasonal changes in EU-rubber content and molecular weight distribution.

SiPM electro-optical detection system noise suppression method

NASA Astrophysics Data System (ADS)

Bi, Xiangli; Yang, Suhui; Hu, Tao; Song, Yiheng

2014-11-01

In this paper, the single photon detection principle of Silicon Photomultipliers (SiPM) device is introduced. The main noise factors that infect the sensitivity of the electro-optical detection system are analyzed, including background light noise, detector dark noise, preamplifier noise and signal light noise etc. The Optical, electrical and thermodynamic methods are used to suppress the SiPM electro-optical detection system noise, which improved the response sensitivity of the detector. Using SiPM optoelectronic detector with a even high sensitivity, together with small field large aperture optical system, high cutoff narrow bandwidth filters, low-noise operational amplifier circuit, the modular design of functional circuit, semiconductor refrigeration technology, greatly improved the sensitivity of optical detection system, reduced system noise and achieved long-range detection of weak laser radiation signal. Theoretical analysis and experimental results show that the proposed methods are reasonable and efficient.

Affinity Biosensors for Detection of Mycotoxins in Food.

PubMed

Evtugyn, Gennady; Subjakova, Veronika; Melikishvili, Sopio; Hianik, Tibor

2018-01-01

This chapter reviews recent achievements in methods of detection of mycotoxins in food. Special focus is on the biosensor technology that utilizes antibodies and nucleic acid aptamers as receptors. Development of biosensors is based on the immobilization of antibodies or aptamers onto various conventional supports like gold layer, but also on nanomaterials such as graphene oxide, carbon nanotubes, and quantum dots that provide an effective platform for achieving high sensitivity of detection using various physical methods, including electrochemical, mass sensitive, and optical. The biosensors developed so far demonstrate high sensitivity typically in subnanomolar limit of detection. Several biosensors have been validated in real samples. The sensitivity of biosensors is similar and, in some cases, even better than traditional analytical methods such as ELISA or chromatography. We believe that future trends will be focused on improving biosensor properties toward practical application in food industry. © 2018 Elsevier Inc. All rights reserved.

A geostatistics-informed hierarchical sensitivity analysis method for complex groundwater flow and transport modeling: GEOSTATISTICAL SENSITIVITY ANALYSIS

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

Dai, Heng; Chen, Xingyuan; Ye, Ming

Sensitivity analysis is an important tool for quantifying uncertainty in the outputs of mathematical models, especially for complex systems with a high dimension of spatially correlated parameters. Variance-based global sensitivity analysis has gained popularity because it can quantify the relative contribution of uncertainty from different sources. However, its computational cost increases dramatically with the complexity of the considered model and the dimension of model parameters. In this study we developed a hierarchical sensitivity analysis method that (1) constructs an uncertainty hierarchy by analyzing the input uncertainty sources, and (2) accounts for the spatial correlation among parameters at each level ofmore » the hierarchy using geostatistical tools. The contribution of uncertainty source at each hierarchy level is measured by sensitivity indices calculated using the variance decomposition method. Using this methodology, we identified the most important uncertainty source for a dynamic groundwater flow and solute transport in model at the Department of Energy (DOE) Hanford site. The results indicate that boundary conditions and permeability field contribute the most uncertainty to the simulated head field and tracer plume, respectively. The relative contribution from each source varied spatially and temporally as driven by the dynamic interaction between groundwater and river water at the site. By using a geostatistical approach to reduce the number of realizations needed for the sensitivity analysis, the computational cost of implementing the developed method was reduced to a practically manageable level. The developed sensitivity analysis method is generally applicable to a wide range of hydrologic and environmental problems that deal with high-dimensional spatially-distributed parameters.« less

High-throughput analysis of sulfatides in cerebrospinal fluid using automated extraction and UPLC-MS/MS.

PubMed

Blomqvist, Maria; Borén, Jan; Zetterberg, Henrik; Blennow, Kaj; Månsson, Jan-Eric; Ståhlman, Marcus

2017-07-01

Sulfatides (STs) are a group of glycosphingolipids that are highly expressed in brain. Due to their importance for normal brain function and their potential involvement in neurological diseases, development of accurate and sensitive methods for their determination is needed. Here we describe a high-throughput oriented and quantitative method for the determination of STs in cerebrospinal fluid (CSF). The STs were extracted using a fully automated liquid/liquid extraction method and quantified using ultra-performance liquid chromatography coupled to tandem mass spectrometry. With the high sensitivity of the developed method, quantification of 20 ST species from only 100 μl of CSF was performed. Validation of the method showed that the STs were extracted with high recovery (90%) and could be determined with low inter- and intra-day variation. Our method was applied to a patient cohort of subjects with an Alzheimer's disease biomarker profile. Although the total ST levels were unaltered compared with an age-matched control group, we show that the ratio of hydroxylated/nonhydroxylated STs was increased in the patient cohort. In conclusion, we believe that the fast, sensitive, and accurate method described in this study is a powerful new tool for the determination of STs in clinical as well as preclinical settings. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

Sensitivity and accuracy of high-throughput metabarcoding methods for early detection of invasive fish species

EPA Science Inventory

For early detection biomonitoring of aquatic invasive species, sensitivity to rare individuals and accurate, high-resolution taxonomic classification are critical to minimize detection errors. Given the great expense and effort associated with morphological identification of many...

Ultra-long high-sensitivity Φ-OTDR for high spatial resolution intrusion detection of pipelines.

PubMed

Peng, Fei; Wu, Han; Jia, Xin-Hong; Rao, Yun-Jiang; Wang, Zi-Nan; Peng, Zheng-Pu

2014-06-02

An ultra-long phase-sensitive optical time domain reflectometry (Φ-OTDR) that can achieve high-sensitivity intrusion detection over 131.5km fiber with high spatial resolution of 8m is presented, which is the longest Φ-OTDR reported to date, to the best of our knowledge. It is found that the combination of distributed Raman amplification with heterodyne detection can extend the sensing distance and enhances the sensitivity substantially, leading to the realization of ultra-long Φ-OTDR with high sensitivity and spatial resolution. Furthermore, the feasibility of applying such an ultra-long Φ-OTDR to pipeline security monitoring is demonstrated and the features of intrusion signal can be extracted with improved SNR by using the wavelet detrending/denoising method proposed.

Methylation-Sensitive High Resolution Melting (MS-HRM).

PubMed

Hussmann, Dianna; Hansen, Lise Lotte

2018-01-01

Methylation-Sensitive High Resolution Melting (MS-HRM) is an in-tube, PCR-based method to detect methylation levels at specific loci of interest. A unique primer design facilitates a high sensitivity of the assays enabling detection of down to 0.1-1% methylated alleles in an unmethylated background.Primers for MS-HRM assays are designed to be complementary to the methylated allele, and a specific annealing temperature enables these primers to anneal both to the methylated and the unmethylated alleles thereby increasing the sensitivity of the assays. Bisulfite treatment of the DNA prior to performing MS-HRM ensures a different base composition between methylated and unmethylated DNA, which is used to separate the resulting amplicons by high resolution melting.The high sensitivity of MS-HRM has proven useful for detecting cancer biomarkers in a noninvasive manner in urine from bladder cancer patients, in stool from colorectal cancer patients, and in buccal mucosa from breast cancer patients. MS-HRM is a fast method to diagnose imprinted diseases and to clinically validate results from whole-epigenome studies. The ability to detect few copies of methylated DNA makes MS-HRM a key player in the quest for establishing links between environmental exposure, epigenetic changes, and disease.

Two-channel highly sensitive sensors based on 4 × 4 multimode interference couplers

NASA Astrophysics Data System (ADS)

Le, Trung-Thanh

2017-12-01

We propose a new kind of microring resonators (MRR) based on 4 × 4 multimode interference (MMI) couplers for multichannel and highly sensitive chemical and biological sensors. The proposed sensor structure has advantages of compactness and high sensitivity compared with the reported sensing structures. By using the transfer matrix method (TMM) and numerical simulations, the designs of the sensor based on silicon waveguides are optimized and demonstrated in detail. We apply our structure to detect glucose and ethanol concentrations simultaneously. A high sensitivity of 9000 nm/RIU, detection limit of 2 × 10‒4 for glucose sensing and sensitivity of 6000 nm/RIU, detection limit of 1.3 × 10‒5 for ethanol sensing are achieved.

Development of high-throughput and high sensitivity capillary gel electrophoresis platform method for Western, Eastern, and Venezuelan equine encephalitis (WEVEE) virus like particles (VLPs) purity determination and characterization.

PubMed

Gollapudi, Deepika; Wycuff, Diane L; Schwartz, Richard M; Cooper, Jonathan W; Cheng, K C

2017-10-01

In this paper, we describe development of a high-throughput, highly sensitive method based on Lab Chip CGE-SDS platform for purity determination and characterization of virus-like particle (VLP) vaccines. A capillary gel electrophoresis approach requiring about 41 s per sample for analysis and demonstrating sensitivity to protein initial concentrations as low as 20 μg/mL, this method has been used previously to evaluate monoclonal antibodies, but this application for lot release assay of VLPs using this platform is unique. The method was qualified and shown to be accurate for the quantitation of VLP purity. Assay repeatability was confirmed to be less than 2% relative standard deviation of the mean (% RSD) with interday precision less than 2% RSD. The assay can evaluate purified VLPs in a concentration range of 20-249 μg/mL for VEE and 20-250 μg/mL for EEE and WEE VLPs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A fast and sensitive TLD method for measurement of energy and homogeneity of electron beams using transmitted radiation through lead.

PubMed

Pradhan, A S; Quast, U; Sharma, P K

1994-09-01

A simple and fast, but sensitive TLD method for the measurement of energy and homogeneity of therapeutically used electron beams has been developed and tested. This method is based on the fact that when small thicknesses of high-Z absorbers such as lead are interposed in the high-energy electron beams, the transmitted radiation increases with the energy of the electron beams. Consequently, the ratio of readouts of TLDS held on the two sides of a lead plate varied sharply (by factor of 70) with a change in energy of the electron beam from 5 MeV to 18 MeV, offering a very sensitive method for the measurement of the energy of electron beams. By using the ratio of TL readouts of two types of TLD ribbon with widely different sensitivities, LiF TLD-700 ribbons on the upstream side and highly sensitive CaF2:Dy TLD-200 ribbons on the downstream side, an electron energy discrimination of better than +/- 0.1 MeV could be achieved. The homogeneity of the electron beam energy and the absorbed dose was measured by using a jig in which the TLDS were held in the desired array on both sides of a 4 mm thick lead plate. The method takes minimal beam time and makes it possible to carry out measurements for the audit of the quality of electron beams as well as for intercomparison of beams by mail.

Development of a Tandem Repeat-Based Polymerase Chain Displacement Reaction Method for Highly Sensitive Detection of 'Candidatus Liberibacter asiaticus'.

PubMed

Lou, Binghai; Song, Yaqin; RoyChowdhury, Moytri; Deng, Chongling; Niu, Ying; Fan, Qijun; Tang, Yan; Zhou, Changyong

2018-02-01

Huanglongbing (HLB) is one of the most destructive diseases in citrus production worldwide. Early detection of HLB pathogens can facilitate timely removal of infected citrus trees in the field. However, low titer and uneven distribution of HLB pathogens in host plants make reliable detection challenging. Therefore, the development of effective detection methods with high sensitivity is imperative. This study reports the development of a novel method, tandem repeat-based polymerase chain displacement reaction (TR-PCDR), for the detection of 'Candidatus Liberibacter asiaticus', a widely distributed HLB-associated bacterium. A uniquely designed primer set (TR2-PCDR-F/TR2-PCDR-1R) and a thermostable Taq DNA polymerase mutant with strand displacement activity were used for TR-PCDR amplification. Performed in a regular thermal cycler, TR-PCDR could produce more than two amplicons after each amplification cycle. Sensitivity of the developed TR-PCDR was 10 copies of target DNA fragment. The sensitive level was proven to be 100× higher than conventional PCR and similar to real-time PCR. Data from the detection of 'Ca. L. asiaticus' with filed samples using the above three methods also showed similar results. No false-positive TR-PCDR amplification was observed from healthy citrus samples and water controls. These results thereby illustrated that the developed TR-PCDR method can be applied to the reliable, highly sensitive, and cost-effective detection of 'Ca. L. asiaticus'.

A model to estimate insulin sensitivity in dairy cows.

PubMed

Holtenius, Paul; Holtenius, Kjell

2007-10-11

Impairment of the insulin regulation of energy metabolism is considered to be an etiologic key component for metabolic disturbances. Methods for studies of insulin sensitivity thus are highly topical. There are clear indications that reduced insulin sensitivity contributes to the metabolic disturbances that occurs especially among obese lactating cows. Direct measurements of insulin sensitivity are laborious and not suitable for epidemiological studies. We have therefore adopted an indirect method originally developed for humans to estimate insulin sensitivity in dairy cows. The method, "Revised Quantitative Insulin Sensitivity Check Index" (RQUICKI) is based on plasma concentrations of glucose, insulin and free fatty acids (FFA) and it generates good and linear correlations with different estimates of insulin sensitivity in human populations. We hypothesized that the RQUICKI method could be used as an index of insulin function in lactating dairy cows. We calculated RQUICKI in 237 apparently healthy dairy cows from 20 commercial herds. All cows included were in their first 15 weeks of lactation. RQUICKI was not affected by the homeorhetic adaptations in energy metabolism that occurred during the first 15 weeks of lactation. In a cohort of 24 experimental cows fed in order to obtain different body condition at parturition RQUICKI was lower in early lactation in cows with a high body condition score suggesting disturbed insulin function in obese cows. The results indicate that RQUICKI might be used to identify lactating cows with disturbed insulin function.

Method and Characterization of Pyroelectric Coefficients for Determining Material Figures of Merit for Infrared (IR) Detectors

DTIC Science & Technology

2013-12-01

and the signal is read as a photocurrent or at a photovoltaic p-n junction. These detectors can provide high-sensitivity and fast refresh rates and...Alternative methods can be used to modulate the sample temperature directly; for example, by using modern Peltier devices and thermoelectric ...commercially-available hardware. The setup consist of three main components: (1) A temperature regulated thermoelectric stage; (2) A high-sensitivity

Non-destructive Testing (NDT) of metal cracks using a high Tc rf-SQUID and eddy current method

NASA Technical Reports Server (NTRS)

Lu, D. F.; Fan, Chang-Xin; Ruan, J. Z.; Han, S. G.; Wong, K. W.; Sun, G. F.

1995-01-01

A SQUID is the most sensitive device to detect change in magnetic field. A nondestructive testing (NDT) device using high temperature SQUID's and eddy current method will be much more sensitive than those currently used eddy current systems, yet much cheaper than one with low temperature SQUID's. In this paper, we present our study of such a NDT device using a high temperature superconducting rf-SQUID as a gradiometer sensor. The result clearly demonstrates the expected sensitivity of the system, and indicates the feasibility of building a portable HTS SQUID NDT device with the help from cryocooler industry. Such a NDT device will have a significant impact on metal corrosion or crack detection technology.

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.

Facile and sensitive determination of N-nitrosamines in food samples by high-performance liquid chromatography via combining fluorescent labeling with dispersive liquid-liquid microextraction.

PubMed

Lu, Shuaimin; Wu, Di; Li, Guoliang; Lv, Zhengxian; Gong, Peiwei; Xia, Lian; Sun, Zhiwei; Chen, Guang; Chen, Xuefeng; You, Jinmao; Wu, Yongning

2017-11-01

The intake of N-nitrosamines (NAs) from foodstuffs is considered to be an important influence factor for several cancers. But the rapid and sensitive screening of NAs remains a challenge in the field of food safety. Inspired by that, a sensitive and rapid method was demonstrated for determination of five NAs (Nitrosopyrrolidine, Nitrosodimethylamine, Nitrosodiethylamine, Nitrosodipropylamine and Nitrosodibutylamine) using dispersive liquid-liquid microextraction (DLLME) followed by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The NAs were firstly denitrosated and labeled by 2-(11H-benzo[a]carbazol-11-yl) ethyl carbonochloridate (BCEC-Cl) and finally enriched by DLLME. Furthermore, the main DLLME conditions were optimized systematically. Under the optimal conditions, satisfactory limits of detection (LODs) were obtained with a range of 0.01-0.07ngg -1 , which were significantly lower than the reported methods. The developed method showed many merits including rapidity, simplicity, high sensitivity and excellent selectivity, which shows a broad prospect in food safety analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Blinded study determination of high sensitivity and specificity microchip electrophoresis–SSCP/HA to detect mutations in the p53 gene

PubMed Central

Hestekin, Christa N.; Lin, Jennifer S.; Senderowicz, Lionel; Jakupciak, John P.; O’Connell, Catherine; Rademaker, Alfred; Barron, Annelise E.

2012-01-01

Knowledge of the genetic changes that lead to disease has grown and continues to grow at a rapid pace. However, there is a need for clinical devices that can be used routinely to translate this knowledge into the treatment of patients. Use in a clinical setting requires high sensitivity and specificity (>97%) in order to prevent misdiagnoses. Single strand conformational polymorphism (SSCP) and heteroduplex analysis (HA) are two DNA-based, complementary methods for mutation detection that are inexpensive and relatively easy to implement. However, both methods are most commonly detected by slab gel electrophoresis, which can be labor-intensive, time-consuming, and often the methods are unable to produce high sensitivity and specificity without the use of multiple analysis conditions. Here we demonstrate the first blinded study using microchip electrophoresis-SSCP/HA. We demonstrate the ability of microchip electrophoresis-SSCP/HA to detect with 98% sensitivity and specificity >100 samples from the p53 gene exons 5–9 in a blinded study in an analysis time of less than 10 minutes. PMID:22002021

Multisite-multivariable sensitivity analysis of distributed watershed models: enhancing the perceptions from computationally frugal methods

USDA-ARS?s Scientific Manuscript database

This paper assesses the impact of different likelihood functions in identifying sensitive parameters of the highly parameterized, spatially distributed Soil and Water Assessment Tool (SWAT) watershed model for multiple variables at multiple sites. The global one-factor-at-a-time (OAT) method of Morr...

Sensitive determination of nitrophenol isomers by reverse-phase high-performance liquid chromatography in conjunction with liquid-liquid extraction

USDA-ARS?s Scientific Manuscript database

A method for the highly sensitive determination of 2-, 3- and 4- nitrophenols was developed using reverse-phase high-performance liquid chromatography (RP-HPLC) with a UV photodiode array detector. Using a reverse-phase column and 40% aqueous acetonitrile as an eluent (i.e. isocratic elution), the i...

A High Sensitivity and Wide Dynamic Range Fiber-Optic Sensor for Low-Concentration VOC Gas Detection

PubMed Central

Khan, Md. Rajibur Rahaman; Kang, Shin-Won

2014-01-01

In this paper, we propose a volatile organic compound (VOC) gas sensing system with high sensitivity and a wide dynamic range that is based on the principle of the heterodyne frequency modulation method. According to this method, the time period of the sensing signal shift when Nile Red containing a VOC-sensitive membrane of a fiber-optic sensing element comes into contact with a VOC. This sensing membrane produces strong, fast and reversible signals when exposed to VOC gases. The response and recovery times of the proposed sensing system were less than 35 s, and good reproducibility and accuracy were obtained. PMID:25490592

Sensitive method to monitor trace quantities of benzanthrone in workers of dyestuff industries

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

Joshi, A.; Khanna, S.K.; Singh, G.B.

1986-03-01

Dyestuff workers coming in contact with benzanthrone (an intermediate used for the synthesis of a variety of dyes) develop skin lesions, gastritis, liver malfunctions, and sexual disturbances. A highly sensitive fluorometric method to monitor trace quantities of benzanthrone in urine, serum, and biological tissues for experimental studies, has been developed. Coupled with simple extraction and resolution, optimum fluorescence is obtained in an equal mixture of chloroform:methanol, detecting as low as 2 ng benzanthrone. This method is approximately 250 times more sensitive than currently available colorimetric assay.

Evaluation of analytical performance of a new high-sensitivity immunoassay for cardiac troponin I.

PubMed

Masotti, Silvia; Prontera, Concetta; Musetti, Veronica; Storti, Simona; Ndreu, Rudina; Zucchelli, Gian Carlo; Passino, Claudio; Clerico, Aldo

2018-02-23

The study aim was to evaluate and compare the analytical performance of the new chemiluminescent immunoassay for cardiac troponin I (cTnI), called Access hs-TnI using DxI platform, with those of Access AccuTnI+3 method, and high-sensitivity (hs) cTnI method for ARCHITECT platform. The limits of blank (LoB), detection (LoD) and quantitation (LoQ) at 10% and 20% CV were evaluated according to international standardized protocols. For the evaluation of analytical performance and comparison of cTnI results, both heparinized plasma samples, collected from healthy subjects and patients with cardiac diseases, and quality control samples distributed in external quality assessment programs were used. LoB, LoD and LoQ at 20% and 10% CV values of the Access hs-cTnI method were 0.6, 1.3, 2.1 and 5.3 ng/L, respectively. Access hs-cTnI method showed analytical performance significantly better than that of Access AccuTnI+3 method and similar results to those of hs ARCHITECT cTnI method. Moreover, the cTnI concentrations measured with Access hs-cTnI method showed close linear regressions with both Access AccuTnI+3 and ARCHITECT hs-cTnI methods, although there were systematic differences between these methods. There was no difference between cTnI values measured by Access hs-cTnI in heparinized plasma and serum samples, whereas there was a significant difference between cTnI values, respectively measured in EDTA and heparin plasma samples. Access hs-cTnI has analytical sensitivity parameters significantly improved compared to Access AccuTnI+3 method and is similar to those of the high-sensitivity method using ARCHITECT platform.

Evaluation of the performance of the reduced local lymph node assay for skin sensitization testing.

PubMed

Ezendam, Janine; Muller, Andre; Hakkert, Betty C; van Loveren, Henk

2013-06-01

The local lymph node assay (LLNA) is the preferred method for classification of sensitizers within REACH. To reduce the number of mice for the identification of sensitizers the reduced LLNA was proposed, which uses only the high dose group of the LLNA. To evaluate the performance of this method for classification, LLNA data from REACH registrations were used and classification based on all dose groups was compared to classification based on the high dose group. We confirmed previous examinations of the reduced LLNA showing that this method is less sensitive compared to the LLNA. The reduced LLNA misclassified 3.3% of the sensitizers identified in the LLNA and misclassification occurred in all potency classes and that there was no clear association with irritant properties. It is therefore not possible to predict beforehand which substances might be misclassified. Another limitation of the reduced LLNA is that skin sensitizing potency cannot be assessed. For these reasons, it is not recommended to use the reduced LLNA as a stand-alone assay for skin sensitization testing within REACH. In the future, the reduced LLNA might be of added value in a weight of evidence approach to confirm negative results obtained with non-animal approaches. Copyright © 2013 Elsevier Inc. All rights reserved.

Convenient, Sensitive and High-Throughput Method for Screening Botanic Origin

NASA Astrophysics Data System (ADS)

Yuan, Yuan; Jiang, Chao; Liu, Libing; Yu, Shulin; Cui, Zhanhu; Chen, Min; Lin, Shufang; Wang, Shu; Huang, Luqi

2014-06-01

In this work, a rapid (within 4-5 h), sensitive and visible new method for assessing botanic origin is developed by combining loop-mediated isothermal amplification with cationic conjugated polymers. The two Chinese medicinal materials (Jin-Yin-Hua and Shan-Yin-Hua) with similar morphology and chemical composition were clearly distinguished by gene SNP genotyping assays. The identification of plant species in Patented Chinese drugs containing Lonicera buds is successfully performed using this detection system. The method is also robust enough to be used in high-throughput screening. This new method is very helpful to identify herbal materials, and is beneficial for detecting safety and quality of botanic products.

Polarization Sensitive Coherent Anti-Stokes Raman Spectroscopy of DCVJ in Doped Polymer

NASA Astrophysics Data System (ADS)

Ujj, Laszlo

2014-05-01

Coherent Raman Microscopy is an emerging technic and method to image biological samples such as living cells by recording vibrational fingerprints of molecules with high spatial resolution. The race is on to record the entire image during the shortest time possible in order to increase the time resolution of the recorded cellular events. The electronically enhanced polarization sensitive version of Coherent anti-Stokes Raman scattering is one of the method which can shorten the recording time and increase the sharpness of an image by enhancing the signal level of special molecular vibrational modes. In order to show the effectiveness of the method a model system, a highly fluorescence sample, DCVJ in a polymer matrix is investigated. Polarization sensitive resonance CARS spectra are recorded and analyzed. Vibrational signatures are extracted with model independent methods. Details of the measurements and data analysis will be presented. The author gratefully acknowledge the UWF for financial support.

A novel in chemico method to detect skin sensitizers in highly diluted reaction conditions.

PubMed

Yamamoto, Yusuke; Tahara, Haruna; Usami, Ryota; Kasahara, Toshihiko; Jimbo, Yoshihiro; Hioki, Takanori; Fujita, Masaharu

2015-11-01

The direct peptide reactivity assay (DPRA) is a simple and versatile alternative method for the evaluation of skin sensitization that involves the reaction of test chemicals with two peptides. However, this method requires concentrated solutions of test chemicals, and hydrophobic substances may not dissolve at the concentrations required. Furthermore, hydrophobic test chemicals may precipitate when added to the reaction solution. We previously established a high-sensitivity method, the amino acid derivative reactivity assay (ADRA). This method uses novel cysteine (NAC) and novel lysine derivatives (NAL), which were synthesized by introducing a naphthalene ring to the amine group of cysteine and lysine residues. In this study, we modified the ADRA method by reducing the concentration of the test chemicals 100-fold. We investigated the accuracy of skin sensitization predictions made using the modified method, which was designated the ADRA-dilutional method (ADRA-DM). The predictive accuracy of the ADRA-DM for skin sensitization was 90% for 82 test chemicals which were also evaluated via the ADRA, and the predictive accuracy in the ADRA-DM was higher than that in the ADRA and DPRA. Furthermore, no precipitation of test compounds was observed at the initiation of the ADRA-DM reaction. These results show that the ADRA-DM allowed the use of test chemicals at concentrations two orders of magnitude lower than that possible with the ADRA. In addition, ADRA-DM does not have the restrictions on test compound solubility that were a major problem with the DPRA. Therefore, the ADRA-DM is a versatile and useful method. Copyright © 2015 John Wiley & Sons, Ltd.

Projection-based estimation and nonuniformity correction of sensitivity profiles in phased-array surface coils.

PubMed

Yun, Sungdae; Kyriakos, Walid E; Chung, Jun-Young; Han, Yeji; Yoo, Seung-Schik; Park, Hyunwook

2007-03-01

To develop a novel approach for calculating the accurate sensitivity profiles of phased-array coils, resulting in correction of nonuniform intensity in parallel MRI. The proposed intensity-correction method estimates the accurate sensitivity profile of each channel of the phased-array coil. The sensitivity profile is estimated by fitting a nonlinear curve to every projection view through the imaged object. The nonlinear curve-fitting efficiently obtains the low-frequency sensitivity profile by eliminating the high-frequency image contents. Filtered back-projection (FBP) is then used to compute the estimates of the sensitivity profile of each channel. The method was applied to both phantom and brain images acquired from the phased-array coil. Intensity-corrected images from the proposed method had more uniform intensity than those obtained by the commonly used sum-of-squares (SOS) approach. With the use of the proposed correction method, the intensity variation was reduced to 6.1% from 13.1% of the SOS. When the proposed approach was applied to the computation of the sensitivity maps during sensitivity encoding (SENSE) reconstruction, it outperformed the SOS approach in terms of the reconstructed image uniformity. The proposed method is more effective at correcting the intensity nonuniformity of phased-array surface-coil images than the conventional SOS method. In addition, the method was shown to be resilient to noise and was successfully applied for image reconstruction in parallel imaging.

Sensitivity and accuracy of high-throughput metabarcoding methods used to describe aquatic communities for early detection of invasve fish species

EPA Science Inventory

For early detection biomonitoring of aquatic invasive species, sensitivity to rare individuals and accurate, high-resolution taxonomic classification are critical to minimize Type I and II detection errors. Given the great expense and effort associated with morphological identifi...

A combination of immunohistochemistry and molecular approaches improves highly sensitive detection of BRAF mutations in papillary thyroid cancer.

PubMed

Martinuzzi, Claudia; Pastorino, Lorenza; Andreotti, Virginia; Garuti, Anna; Minuto, Michele; Fiocca, Roberto; Bianchi-Scarrà, Giovanna; Ghiorzo, Paola; Grillo, Federica; Mastracci, Luca

2016-09-01

The optimal method for BRAF mutation detection remains to be determined despite advances in molecular detection techniques. The aim of this study was to compare, against classical Sanger sequencing, the diagnostic performance of two of the most recently developed, highly sensitive methods: BRAF V600E immunohistochemistry (IHC) and peptide nucleic-acid (PNA)-clamp qPCR. BRAF exon 15 mutations were searched in formalin-fixed paraffin-embedded tissues from 86 papillary thyroid carcinoma using the three methods. The limits of detection of Sanger sequencing in borderline or discordant cases were quantified by next generation sequencing. BRAF mutations were found in 74.4 % of cases by PNA, in 71 % of cases by IHC, and in 64 % of cases by Sanger sequencing. Complete concordance for the three methods was observed in 80 % of samples. Better concordance was observed with the combination of two methods, particularly PNA and IHC (59/64) (92 %), while the combination of PNA and Sanger was concordant in 55 cases (86 %). Sensitivity of the three methods was 99 % for PNA, 94.2 % for IHC, and 89.5 % for Sanger. Our data show that IHC could be used as a cost-effective, first-line method for BRAF V600E detection in daily practice, followed by PNA analysis in negative or uninterpretable cases, as the most efficient method. PNA-clamp quantitative PCR is highly sensitive and complementary to IHC as it also recognizes other mutations besides V600E and it is suitable for diagnostic purposes.

An approach to the diagnosis of metabolic syndrome by the multi-electrode impedance method

NASA Astrophysics Data System (ADS)

Furuya, N.; Sakamoto, K.; Kanai, H.

2010-04-01

It is well known that metabolic syndrome can induce myocardial infarction and cerebral infarction. So, it is very important to measure the visceral fat volume. In the electric impedance method, information in the vicinity of the electrodes is strongly reflected. Therefore, we propose a new multi-electrode arrangement method based on the impedance sensitivity theorem to measure the visceral fat volume. This electrode arrangement is designed to enable high impedance sensitivity in the visceral and subcutaneous fat regions. Currents are simultaneously applied to several current electrodes on the body surface, and one voltage electrode pair is arranged on the body surface near the organ of interest to obtain the visceral fat information and another voltage electrode pair is arranged on the body surface near the current electrodes to obtain the subcutaneous fat information. A simulation study indicates that by weighting the impedance sensitivity distribution, as in our method, a high-sensitivity region in the visceral and the subcutaneous fat regions can be formed. In addition, it was confirmed that the visceral fat volume can be estimated by the measured impedance data.

A Highly Sensitive Diagnostic System for Detecting Dengue Viruses Using the Interaction between a Sulfated Sugar Chain and a Virion.

PubMed

Saksono, Budi; Dewi, Beti Ernawati; Nainggolan, Leonardo; Suda, Yasuo

2015-01-01

We propose a novel method of detecting trace amounts of dengue virus (DENVs) from serum. Our method is based on the interaction between a sulfated sugar chain and a DENV surface glycoprotein. After capturing DENV with the sulfated sugar chain-immobilized gold nanoparticles (SGNPs), the resulting complex is precipitated and viral RNA content is measured using the reverse-transcription quantitative polymerase chain reaction SYBR Green I (RT-qPCR-Syb) method. Sugar chains that bind to DENVs were identified using the array-type sugar chain immobilized chip (Sugar Chip) and surface plasmon resonance (SPR) imaging. Heparin and low-molecular-weight dextran sulfate were identified as binding partners, and immobilized on gold nanoparticles to prepare 3 types of SGNPs. The capacity of these SGNPs to capture and concentrate trace amounts of DENVs was evaluated in vitro. The SGNP with greatest sensitivity was tested using clinical samples in Indonesia in 2013-2014. As a result, the novel method was able to detect low concentrations of DENVs using only 6 μL of serum, with similar sensitivity to that of a Qiagen RNA extraction kit using 140 μL of serum. In addition, this method allows for multiplex-like identification of serotypes of DENVs. This feature is important for good healthcare management of DENV infection in order to safely diagnose the dangerous, highly contagious disease quickly, with high sensitivity.

Non-destructive testing (NDT) of metal cracks using a high Tc rf-SQUID and eddy current method

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

Lu, D.F.; Fan, C.; Ruan, J.Z.

1994-12-31

A SQUID is the most sensitive device to detect change in magnetic field. A non-destructive testing (NDT) device using high temperature SQUIDs and eddy current method will be much more sensitive than those currently used eddy current systems, yet much cheaper than one with low temperature SQUIDs. In this paper, we present our study of such a NDT device using a high temperature superconducting rf-SQUID as a gradiometer sensor. The result clearly demonstrates the expected sensitivity of the system, and indicates the feasibility of building a portable HTS SQUID NDT device with the help from cryocooler industry. Such a NDTmore » device will have a significant impact on metal corrosion or crack detection technology.« less

Pyocin-sensitivity testing as a method of typing Pseudomonas aeruginosa: use of "phage-free" preparations of pyocin.

PubMed

Rampling, A; Whitby, J L; Wildy, P

1975-11-01

A method for pyocin-sensitivity typing by means of "phage-free" preparations of pyocin is described. The method was tested on 227 isolates of P. aeruginosa, collected from 34 different foci of infection in hospitals in the British Isles and the results were compared with those for combined serological and phage typing of all strains and pyocin production of 105 of the isolates. It is concluded that pyocin-sensitivity typing is a simple and reliable method giving a high degree of discrimination, comparable to that of combined serological and phage typing, and it is suitable for use in routine hospital laboratories.

Highly Sensitive and Selective Ethanol Sensor Fabricated with In-Doped 3DOM ZnO.

PubMed

Wang, Zhihua; Tian, Ziwei; Han, Dongmei; Gu, Fubo

2016-03-02

ZnO is an important n-type semiconductor sensing material. Currently, much attention has been attracted to finding an effective method to prepare ZnO nanomaterials with high sensing sensitivity and excellent selectivity. A three-dimensionally ordered macroporous (3DOM) ZnO nanostructure with a large surface area is beneficial to gas and electron transfer, which can enhance the gas sensitivity of ZnO. Indium (In) doping is an effective way to improve the sensing properties of ZnO. In this paper, In-doped 3DOM ZnO with enhanced sensitivity and selectivity has been synthesized by using a colloidal crystal templating method. The 3DOM ZnO with 5 at. % of In-doping exhibits the highest sensitivity (∼88) to 100 ppm ethanol at 250 °C, which is approximately 3 times higher than that of pure 3DOM ZnO. The huge improvement to the sensitivity to ethanol was attributed to the increase in the surface area and the electron carrier concentration. The doping by In introduces more electrons into the matrix, which is helpful for increasing the amount of adsorbed oxygen, leading to high sensitivity. The In-doped 3DOM ZnO is a promising material for a new type of ethanol sensor.

A rapid method to visualize von willebrand factor multimers by using agarose gel electrophoresis, immunolocalization and luminographic detection.

PubMed

Krizek, D R; Rick, M E

2000-03-15

A highly sensitive and rapid clinical method for the visualization of the multimeric structure of von Willebrand Factor in plasma and platelets is described. The method utilizes submerged horizontal agarose gel electrophoresis, followed by transfer of the von Willebrand Factor onto a polyvinylidine fluoride membrane, and immunolocalization and luminographic visualization of the von Willebrand Factor multimeric pattern. This method distinguishes type 1 from types 2A and 2B von Willebrand disease, allowing timely evaluation and classification of von Willebrand Factor in patient plasma. It also allows visualization of the unusually high molecular weight multimers present in platelets. There are several major advantages to this method including rapid processing, simplicity of gel preparation, high sensitivity to low concentrations of von Willebrand Factor, and elimination of radioactivity.

Highly sensitive refractive index fiber inline Mach-Zehnder interferometer fabricated by femtosecond laser micromachining and chemical etching

NASA Astrophysics Data System (ADS)

Sun, Xiao-Yan; Chu, Dong-Kai; Dong, Xin-Ran; Zhou, Chu; Li, Hai-Tao; Luo-Zhi; Hu, You-Wang; Zhou, Jian-Ying; Cong-Wang; Duan, Ji-An

2016-03-01

A High sensitive refractive index (RI) sensor based on Mach-Zehnder interferometer (MZI) in a conventional single-mode optical fiber is proposed, which is fabricated by femtosecond laser transversal-scanning inscription method and chemical etching. A rectangular cavity structure is formed in part of fiber core and cladding interface. The MZI sensor shows excellent refractive index sensitivity and linearity, which exhibits an extremely high RI sensitivity of -17197 nm/RIU (refractive index unit) with the linearity of 0.9996 within the refractive index range of 1.3371-1.3407. The experimental results are consistent with theoretical analysis.

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

Ogura, Toshihiko, E-mail: t-ogura@aist.go.jp

Highlights: • We developed a high-sensitive frequency transmission electric-field (FTE) system. • The output signal was highly enhanced by applying voltage to a metal layer on SiN. • The spatial resolution of new FTE method is 41 nm. • New FTE system enables observation of the intact bacteria and virus in water. - Abstract: The high-resolution structural analysis of biological specimens by scanning electron microscopy (SEM) presents several advantages. Until now, wet bacterial specimens have been examined using atmospheric sample holders. However, images of unstained specimens in water using these holders exhibit very poor contrast and heavy radiation damage. Recently,more » we developed the frequency transmission electric-field (FTE) method, which facilitates the SEM observation of biological specimens in water without radiation damage. However, the signal detection system presents low sensitivity. Therefore, a high EB current is required to generate clear images, and thus reducing spatial resolution and inducing thermal damage to the samples. Here a high-sensitivity detection system is developed for the FTE method, which enhances the output signal amplitude by hundredfold. The detection signal was highly enhanced when voltage was applied to the metal layer on silicon nitride thin film. This enhancement reduced the EB current and improved the spatial resolution as well as the signal-to-noise ratio. The spatial resolution of a high-sensitive FTE system is 41 nm, which is considerably higher than previous FTE system. New FTE system can easily be utilised to examine various unstained biological specimens in water, such as living bacteria and viruses.« less

Visual and highly sensitive detection of cancer cells by a colorimetric aptasensor based on cell-triggered cyclic enzymatic signal amplification.

PubMed

Zhang, Xianxia; Xiao, Kunyi; Cheng, Liwei; Chen, Hui; Liu, Baohong; Zhang, Song; Kong, Jilie

2014-06-03

Rapid and efficient detection of cancer cells at their earliest stages is one of the central challenges in cancer diagnostics. We developed a simple, cost-effective, and highly sensitive colorimetric method for visually detecting rare cancer cells based on cell-triggered cyclic enzymatic signal amplification (CTCESA). In the absence of target cells, hairpin aptamer probes (HAPs) and linker DNAs stably coexist in solution, and the linker DNA assembles DNA-AuNPs, producing a purple solution. In the presence of target cells, the specific binding of HAPs to the target cells triggers a conformational switch that results in linker DNA hybridization and cleavage by nicking endonuclease-strand scission cycles. Consequently, the cleaved fragments of linker DNA can no longer assemble into DNA-AuNPs, resulting in a red color. UV-vis spectrometry and photograph analyses demonstrated that this CTCESA-based method exhibited selective and sensitive colorimetric responses to the presence of target CCRF-CEM cells, which could be detected by the naked eye. The linear response for CCRF-CEM cells in a concentration range from 10(2) to 10(4) cells was obtained with a detection limit of 40 cells, which is approximately 20 times lower than the detection limit of normal AuNP-based methods without amplification. Given the high specificity and sensitivity of CTCESA, this colorimetric method provides a sensitive, label-free, and cost-effective approach for early cancer diagnosis and point-to-care applications.

High-sensitivity and large-dynamic-range refractive index sensors employing weak composite Fabry-Perot cavities.

PubMed

Chen, Pengcheng; Shu, Xuewen; Cao, Haoran; Sugden, Kate

2017-08-15

Most sensors face a common trade-off between high sensitivity and a large dynamic range. We demonstrate here an all-fiber refractometer based on a dual-cavity Fabry-Perot interferometer (FPI) that possesses the advantage of both high sensitivity and a large dynamic range. Since the two composite cavities have a large cavity length difference, one can observe both fine and coarse fringes, which correspond to the long cavity and the short cavity, respectively. The short-cavity FPI and the use of an intensity demodulation method mean that the individual fine fringe dips correspond to a series of quasi-continuous highly sensitive zones for refractive index measurement. By calculating the parameters of the composite FPI, we find that the range of the ultra-sensitive zones can be considerably adjusted to suit the end requirements. The experimental trends are in good agreement with the theoretical predictions. The co-existence of high sensitivity and a large dynamic range in a composite FPI is of great significance to practical RI measurements.

Ultrasonic-assisted extraction and dispersive liquid-liquid microextraction combined with gas chromatography-mass spectrometry as an efficient and sensitive method for determining of acrylamide in potato chips samples.

PubMed

Zokaei, Maryam; Abedi, Abdol-Samad; Kamankesh, Marzieh; Shojaee-Aliababadi, Saeedeh; Mohammadi, Abdorreza

2017-11-01

In this research, for the first time, we successfully developed ultrasonic-assisted extraction and dispersive liquid-liquid microextraction combined with gas chromatography-mass spectrometry as a new, fast and highly sensitive method for determining of acrylamide in potato chips samples. Xanthydrol was used as a derivatization reagent and parameters affecting in the derivatization and microextraction steps were studied and optimized. Under optimum conditions, the calibration curves showed high levels of linearity (R 2 >0.9993) for acrylamide in the range of 2-500ngmL -1 . The relative standard deviation (RSD) for the seven analyses was 6.8%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.6ngg -1 and 2ngg -1 , respectively. The UAE-DLLME-GC-MS method demonstrated high sensitivity, good linearity, recovery, and enrichment factor. The performance of the new proposed method was evaluated for the determination of acrylamide in various types of chips samples and satisfactory results were obtained. Copyright © 2017 Elsevier Ltd. All rights reserved.

Coupled Aerodynamic and Structural Sensitivity Analysis of a High-Speed Civil Transport

NASA Technical Reports Server (NTRS)

Mason, B. H.; Walsh, J. L.

2001-01-01

An objective of the High Performance Computing and Communication Program at the NASA Langley Research Center is to demonstrate multidisciplinary shape and sizing optimization of a complete aerospace vehicle configuration by using high-fidelity, finite-element structural analysis and computational fluid dynamics aerodynamic analysis. In a previous study, a multi-disciplinary analysis system for a high-speed civil transport was formulated to integrate a set of existing discipline analysis codes, some of them computationally intensive, This paper is an extension of the previous study, in which the sensitivity analysis for the coupled aerodynamic and structural analysis problem is formulated and implemented. Uncoupled stress sensitivities computed with a constant load vector in a commercial finite element analysis code are compared to coupled aeroelastic sensitivities computed by finite differences. The computational expense of these sensitivity calculation methods is discussed.

Efficient monitoring of the blood-stage infection in a malaria rodent model by the rotating-crystal magneto-optical method

NASA Astrophysics Data System (ADS)

Orbán, Ágnes; Rebelo, Maria; Molnár, Petra; Albuquerque, Inês S.; Butykai, Adam; Kézsmárki, István

2016-03-01

Intense research efforts have been focused on the improvement of the efficiency and sensitivity of malaria diagnostics, especially in resource-limited settings for the detection of asymptomatic infections. Our recently developed magneto-optical (MO) method allows the accurate quantification of malaria pigment crystals (hemozoin) in blood by their magnetically induced rotation. First evaluations of the method using β-hematin crystals and in vitro P. falciparum cultures implied its potential for high-sensitivity malaria diagnosis. To further investigate this potential, here we study the performance of the method in monitoring the in vivo onset and progression of the blood-stage infection in a rodent malaria model. Our results show that the MO method can detect the first generation of intraerythrocytic P. berghei parasites 66-76 hours after sporozoite injection, demonstrating similar sensitivity to Giesma-stained light microscopy and exceeding that of flow cytometric techniques. Magneto-optical measurements performed during and after the treatment of P. berghei infections revealed that both the follow up under treatment and the detection of later reinfections are feasible with this new technique. The present study demonstrates that the MO method - besides being label and reagent-free, automated and rapid - has a high in vivo sensitivity and is ready for in-field evaluation.

Highly sensitive protein detection by biospecific AFM-based fishing with pulsed electrical stimulation.

PubMed

Pleshakova, Tatyana O; Malsagova, Kristina A; Kaysheva, Anna L; Kopylov, Arthur T; Tatur, Vadim Yu; Ziborov, Vadim S; Kanashenko, Sergey L; Galiullin, Rafael A; Ivanov, Yuri D

2017-08-01

We report here the highly sensitive detection of protein in solution at concentrations from 10 -15 to 10 -18 m using the combination of atomic force microscopy (AFM) and mass spectrometry. Biospecific detection of biotinylated bovine serum albumin was carried out by fishing out the protein onto the surface of AFM chips with immobilized avidin, which determined the specificity of the analysis. Electrical stimulation was applied to enhance the fishing efficiency. A high sensitivity of detection was achieved by application of nanosecond electric pulses to highly oriented pyrolytic graphite placed under the AFM chip. A peristaltic pump-based flow system, which is widely used in routine bioanalytical assays, was employed throughout the analysis. These results hold promise for the development of highly sensitive protein detection methods using nanosensor devices.

Next Generation Flow for highly sensitive and standardized detection of minimal residual disease in multiple myeloma.

PubMed

Flores-Montero, J; Sanoja-Flores, L; Paiva, B; Puig, N; García-Sánchez, O; Böttcher, S; van der Velden, V H J; Pérez-Morán, J-J; Vidriales, M-B; García-Sanz, R; Jimenez, C; González, M; Martínez-López, J; Corral-Mateos, A; Grigore, G-E; Fluxá, R; Pontes, R; Caetano, J; Sedek, L; Del Cañizo, M-C; Bladé, J; Lahuerta, J-J; Aguilar, C; Bárez, A; García-Mateo, A; Labrador, J; Leoz, P; Aguilera-Sanz, C; San-Miguel, J; Mateos, M-V; Durie, B; van Dongen, J J M; Orfao, A

2017-10-01

Flow cytometry has become a highly valuable method to monitor minimal residual disease (MRD) and evaluate the depth of complete response (CR) in bone marrow (BM) of multiple myeloma (MM) after therapy. However, current flow-MRD has lower sensitivity than molecular methods and lacks standardization. Here we report on a novel next generation flow (NGF) approach for highly sensitive and standardized MRD detection in MM. An optimized 2-tube 8-color antibody panel was constructed in five cycles of design-evaluation-redesign. In addition, a bulk-lysis procedure was established for acquisition of ⩾10 7 cells/sample, and novel software tools were constructed for automatic plasma cell gating. Multicenter evaluation of 110 follow-up BM from MM patients in very good partial response (VGPR) or CR showed a higher sensitivity for NGF-MRD vs conventional 8-color flow-MRD -MRD-positive rate of 47 vs 34% (P=0.003)-. Thus, 25% of patients classified as MRD-negative by conventional 8-color flow were MRD-positive by NGF, translating into a significantly longer progression-free survival for MRD-negative vs MRD-positive CR patients by NGF (75% progression-free survival not reached vs 7 months; P=0.02). This study establishes EuroFlow-based NGF as a highly sensitive, fully standardized approach for MRD detection in MM which overcomes the major limitations of conventional flow-MRD methods and is ready for implementation in routine diagnostics.

Particle swarm optimization method for small retinal vessels detection on multiresolution fundus images.

PubMed

Khomri, Bilal; Christodoulidis, Argyrios; Djerou, Leila; Babahenini, Mohamed Chaouki; Cheriet, Farida

2018-05-01

Retinal vessel segmentation plays an important role in the diagnosis of eye diseases and is considered as one of the most challenging tasks in computer-aided diagnosis (CAD) systems. The main goal of this study was to propose a method for blood-vessel segmentation that could deal with the problem of detecting vessels of varying diameters in high- and low-resolution fundus images. We proposed to use the particle swarm optimization (PSO) algorithm to improve the multiscale line detection (MSLD) method. The PSO algorithm was applied to find the best arrangement of scales in the MSLD method and to handle the problem of multiscale response recombination. The performance of the proposed method was evaluated on two low-resolution (DRIVE and STARE) and one high-resolution fundus (HRF) image datasets. The data include healthy (H) and diabetic retinopathy (DR) cases. The proposed approach improved the sensitivity rate against the MSLD by 4.7% for the DRIVE dataset and by 1.8% for the STARE dataset. For the high-resolution dataset, the proposed approach achieved 87.09% sensitivity rate, whereas the MSLD method achieves 82.58% sensitivity rate at the same specificity level. When only the smallest vessels were considered, the proposed approach improved the sensitivity rate by 11.02% and by 4.42% for the healthy and the diabetic cases, respectively. Integrating the proposed method in a comprehensive CAD system for DR screening would allow the reduction of false positives due to missed small vessels, misclassified as red lesions. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Geochemistry of biomolecules

NASA Technical Reports Server (NTRS)

Bonner, J.

1976-01-01

A highly sensitive fluorometric technique is developed for the determination of biological and geo-organic compounds in ancient sediments and extraterrestrial samples. This technique is used to establish chemical evidence for fossil pigments in an extraterrestrial sample. Also developed is a highly sensitive and specific fluorometric method for the determination of total primary amine nitrogen in soil samples.

Improving multi-objective reservoir operation optimization with sensitivity-informed dimension reduction

NASA Astrophysics Data System (ADS)

Chu, J.; Zhang, C.; Fu, G.; Li, Y.; Zhou, H.

2015-08-01

This study investigates the effectiveness of a sensitivity-informed method for multi-objective operation of reservoir systems, which uses global sensitivity analysis as a screening tool to reduce computational demands. Sobol's method is used to screen insensitive decision variables and guide the formulation of the optimization problems with a significantly reduced number of decision variables. This sensitivity-informed method dramatically reduces the computational demands required for attaining high-quality approximations of optimal trade-off relationships between conflicting design objectives. The search results obtained from the reduced complexity multi-objective reservoir operation problems are then used to pre-condition the full search of the original optimization problem. In two case studies, the Dahuofang reservoir and the inter-basin multi-reservoir system in Liaoning province, China, sensitivity analysis results show that reservoir performance is strongly controlled by a small proportion of decision variables. Sensitivity-informed dimension reduction and pre-conditioning are evaluated in their ability to improve the efficiency and effectiveness of multi-objective evolutionary optimization. Overall, this study illustrates the efficiency and effectiveness of the sensitivity-informed method and the use of global sensitivity analysis to inform dimension reduction of optimization problems when solving complex multi-objective reservoir operation problems.

GRIDSS: sensitive and specific genomic rearrangement detection using positional de Bruijn graph assembly

PubMed Central

Do, Hongdo; Molania, Ramyar

2017-01-01

The identification of genomic rearrangements with high sensitivity and specificity using massively parallel sequencing remains a major challenge, particularly in precision medicine and cancer research. Here, we describe a new method for detecting rearrangements, GRIDSS (Genome Rearrangement IDentification Software Suite). GRIDSS is a multithreaded structural variant (SV) caller that performs efficient genome-wide break-end assembly prior to variant calling using a novel positional de Bruijn graph-based assembler. By combining assembly, split read, and read pair evidence using a probabilistic scoring, GRIDSS achieves high sensitivity and specificity on simulated, cell line, and patient tumor data, recently winning SV subchallenge #5 of the ICGC-TCGA DREAM8.5 Somatic Mutation Calling Challenge. On human cell line data, GRIDSS halves the false discovery rate compared to other recent methods while matching or exceeding their sensitivity. GRIDSS identifies nontemplate sequence insertions, microhomologies, and large imperfect homologies, estimates a quality score for each breakpoint, stratifies calls into high or low confidence, and supports multisample analysis. PMID:29097403

Mesoporous structured MIPs@CDs fluorescence sensor for highly sensitive detection of TNT.

PubMed

Xu, Shoufang; Lu, Hongzhi

2016-11-15

A facile strategy was developed to prepare mesoporous structured molecularly imprinted polymers capped carbon dots (M-MIPs@CDs) fluorescence sensor for highly sensitive and selective determination of TNT. The strategy using amino-CDs directly as "functional monomer" for imprinting simplify the imprinting process and provide well recognition sites accessibility. The as-prepared M-MIPs@CDs sensor, using periodic mesoporous silica as imprinting matrix, and amino-CDs directly as "functional monomer", exhibited excellent selectivity and sensitivity toward TNT with detection limit of 17nM. The recycling process was sustainable for 10 times without obvious efficiency decrease. The feasibility of the developed method in real samples was successfully evaluated through the analysis of TNT in soil and water samples with satisfactory recoveries of 88.6-95.7%. The method proposed in this work was proved to be a convenient and practical way to prepare high sensitive and selective fluorescence MIPs@CDs sensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Low-cost polarization microscopy for cholesterol crystals

NASA Astrophysics Data System (ADS)

Kim, Kyungmin; Cho, Seonghee; Kim, Taehoon; Park, Hyoeun; Kim, Jinmoo; Lee, Seunghoon; Kang, Yeonsu; Chang, Kiyuk; Kim, Chulhong

2018-02-01

Because cholesterol crystals (Chcs) are a major cause of atherosclerosis, imaging Chcs in tissues with high sensitivity and specificity is important in diagnosing and predicting atherosclerosis. Polarizing microscopy (PM) has been widely used to image crystalline materials in tissues, but it has been difficult to distinguish Chcs from other crystalline materials in tissues. Thus, various methods such as fluorescent dye staining, Raman spectroscopy, and two-photon microscopy (TPM) have been developed to image Chcs with high sensitivity and specificity. However, these methods require expensive equipment or complex processes. Therefore, we have developed a low-cost, easy-to-use PM system using an LED light source that can distinguish Chcs from other crystalline materials with high sensitivity and specificity. Due to the nature of the LED spectrum in our system, collagen is displayed in yellow and Chcs in blue. In addition, we have improved the sensitivity and specificity by creating an aqueous condition on the sample. In the aqueous state, signals of yellowish collagen fibers were reduced and signals of Chcs were highlighted. The Chcs detection capability of our system was verified compared with the TPM image. In addition, clinical feasibility was shown by comparison with existing histological methods.

Vibrational Action Spectroscopy of Solids: New Surface-Sensitive Technique

NASA Astrophysics Data System (ADS)

Wu, Zongfang; Płucienik, Agata; Feiten, Felix E.; Naschitzki, Matthias; Wachsmann, Walter; Gewinner, Sandy; Schöllkopf, Wieland; Staemmler, Volker; Kuhlenbeck, Helmut; Freund, Hans-Joachim

2017-09-01

Vibrational action spectroscopy employing infrared radiation from a free-electron laser has been successfully used for many years to study the vibrational and structural properties of gas phase aggregates. Despite the high sensitivity of this method no relevant studies have yet been conducted for solid sample surfaces. We have set up an experiment for the application of this method to such targets, using infrared light from the free-electron laser of the Fritz Haber Institute. In this Letter, we present first results of this technique with adsorbed argon and neon atoms as messengers. We were able to detect surface-located vibrations of a thin V2O3(0 0 0 1 ) film on Au(111) as well as adsorbate vibrations, demonstrating that this method is highly surface sensitive. We consider that the dominant channel for desorption of the messenger atoms is direct inharmonic vibrational coupling, which is essentially insensitive to subsurface or bulk vibrations. Another channel is thermal desorption due to sample heating by absorption of infrared light. The high surface sensitivity of the nonthermal channel and its insensitivity to subsurface modes makes this technique an ideal tool for the study of surface-located vibrations.

Vibrational Action Spectroscopy of Solids: New Surface-Sensitive Technique.

PubMed

Wu, Zongfang; Płucienik, Agata; Feiten, Felix E; Naschitzki, Matthias; Wachsmann, Walter; Gewinner, Sandy; Schöllkopf, Wieland; Staemmler, Volker; Kuhlenbeck, Helmut; Freund, Hans-Joachim

2017-09-29

Vibrational action spectroscopy employing infrared radiation from a free-electron laser has been successfully used for many years to study the vibrational and structural properties of gas phase aggregates. Despite the high sensitivity of this method no relevant studies have yet been conducted for solid sample surfaces. We have set up an experiment for the application of this method to such targets, using infrared light from the free-electron laser of the Fritz Haber Institute. In this Letter, we present first results of this technique with adsorbed argon and neon atoms as messengers. We were able to detect surface-located vibrations of a thin V_{2}O_{3}(0001) film on Au(111) as well as adsorbate vibrations, demonstrating that this method is highly surface sensitive. We consider that the dominant channel for desorption of the messenger atoms is direct inharmonic vibrational coupling, which is essentially insensitive to subsurface or bulk vibrations. Another channel is thermal desorption due to sample heating by absorption of infrared light. The high surface sensitivity of the nonthermal channel and its insensitivity to subsurface modes makes this technique an ideal tool for the study of surface-located vibrations.

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.

Blinded study determination of high sensitivity and specificity microchip electrophoresis-SSCP/HA to detect mutations in the p53 gene.

PubMed

Hestekin, Christa N; Lin, Jennifer S; Senderowicz, Lionel; Jakupciak, John P; O'Connell, Catherine; Rademaker, Alfred; Barron, Annelise E

2011-11-01

Knowledge of the genetic changes that lead to disease has grown and continues to grow at a rapid pace. However, there is a need for clinical devices that can be used routinely to translate this knowledge into the treatment of patients. Use in a clinical setting requires high sensitivity and specificity (>97%) in order to prevent misdiagnoses. Single-strand conformational polymorphism (SSCP) and heteroduplex analysis (HA) are two DNA-based, complementary methods for mutation detection that are inexpensive and relatively easy to implement. However, both methods are most commonly detected by slab gel electrophoresis, which can be labor-intensive, time-consuming, and often the methods are unable to produce high sensitivity and specificity without the use of multiple analysis conditions. Here, we demonstrate the first blinded study using microchip electrophoresis (ME)-SSCP/HA. We demonstrate the ability of ME-SSCP/HA to detect with 98% sensitivity and specificity >100 samples from the p53 gene exons 5-9 in a blinded study in an analysis time of <10 min. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liquid-phase exfoliated graphene as highly-sensitive sensor for simultaneous determination of endocrine disruptors: diethylstilbestrol and estradiol.

PubMed

Hu, Lintong; Cheng, Qin; Chen, Danchao; Ma, Ming; Wu, Kangbing

2015-01-01

It is quite important to develop convenient and rapid analytical methods for trace levels of endocrine disruptors because they heavily affect health and reproduction of humans and animals. Herein, graphene was easily prepared via one-step exfoliation using N-methyl-2-pyrrolidone as solvent, and then used to construct an electrochemical sensor for highly-sensitive detection of diethylstilbestrol (DES) and estradiol (E2). On the surface of prepared graphene film, two independent and greatly-increased oxidation waves were observed at 0.28V and 0.49V for DES and E2. The remarkable signal enlargements indicated that the detection sensitivity was improved significantly. The influences of pH value, amount of graphene and accumulation time on the oxidation signals of DES and E2 were discussed. As a result, a highly-sensitive and rapid electrochemical method was newly developed for simultaneous detection of DES and E2. The values of detection limit were evaluated to be 10.87 nM and 4.9 nM for DES and E2. Additionally, this new method was successfully used in lake water samples and the accuracy was satisfactory. Copyright © 2014 Elsevier B.V. All rights reserved.

Long-Period Gratings in Highly Germanium-Doped, Single-Mode Optical Fibers for Sensing Applications

PubMed Central

Schlangen, Sebastian; Bremer, Kort; Zheng, Yulong; Böhm, Sebastian; Steinke, Michael; Wellmann, Felix; Neumann, Jörg; Overmeyer, Ludger

2018-01-01

Long-period fiber gratings (LPGs) are well known for their sensitivity to external influences, which make them interesting for a large number of sensing applications. For these applications, fibers with a high numerical aperture (i.e., fibers with highly germanium (Ge)-doped fused silica fiber cores) are more attractive since they are intrinsically photosensitive, as well as less sensitive to bend- and microbend-induced light attenuations. In this work, we introduce a novel method to inscribe LPGs into highly Ge-doped, single-mode fibers. By tapering the optical fiber, and thus, tailoring the effective indices of the core and cladding modes, for the first time, an LPG was inscribed into such fibers using the amplitude mask technique and a KrF excimer laser. Based on this novel method, sensitive LPG-based fiber optic sensors only a few millimeters in length can be incorporated in bend-insensitive fibers for use in various monitoring applications. Moreover, by applying the described inscription method, the LPG spectrum can be influenced and tailored according to the specific demands of a particular application. PMID:29702600

Highly sensitive fluorescence detection of metastatic lymph nodes of gastric cancer with photo-oxidation of protoporphyrin IX.

PubMed

Koizumi, N; Harada, Y; Beika, M; Minamikawa, T; Yamaoka, Y; Dai, P; Murayama, Y; Yanagisawa, A; Otsuji, E; Tanaka, H; Takamatsu, T

2016-08-01

The establishment of a precise and rapid method to detect metastatic lymph nodes (LNs) is essential to perform less invasive surgery with reduced gastrectomy along with reduced lymph node dissection. We herein describe a novel imaging strategy to detect 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) fluorescence in excised LNs specifically with reduced effects of tissue autofluorescence based on photo-oxidation of PpIX. We applied the method in a clinical setting, and evaluated its feasibility. To reduce the unfavorable effect of autofluorescence, we focused on photo-oxidation of PpIX: Following light irradiation, PpIX changes into another substance, photo-protoporphyrin, via an oxidative process, which has a different spectral peak, at 675 nm, whereas PpIX has its spectral peak at 635 nm. Based on the unique spectral alteration, fluorescence spectral imaging before and after light irradiation and subsequent originally-developed image processing was performed. Following in vitro study, we applied this method to a total of 662 excised LNs obtained from 30 gastric cancer patients administered 5-ALA preoperatively. Specific visualization of PpIX was achieved in in vitro study. The method allowed highly sensitive detection of metastatic LNs, with sensitivity of 91.9% and specificity of 90.8% in the in vivo clinical trial. Receiver operating characteristic analysis indicated high diagnostic accuracy, with the area under the curve of 0.926. We established a highly sensitive and specific 5-ALA-induced fluorescence imaging method applicable in clinical settings. The novel method has a potential to become a useful tool for intraoperative rapid diagnosis of LN metastasis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Resonance Rayleigh scattering method for highly sensitive detection of chitosan using aniline blue as probe

NASA Astrophysics Data System (ADS)

Zhang, Weiai; Ma, Caijuan; Su, Zhengquan; Bai, Yan

2016-11-01

This paper describes a highly sensitive and accurate approach using aniline blue (AB) (water soluble) as a probe to determine chitosan (CTS) through Resonance Rayleigh scattering (RRS). Under optimum experimental conditions, the intensities of RRS were linearly proportional to the concentration of CTS in the range from 0.01 to 3.5 μg/mL, and the limit of detection (LOD) was 6.94 ng/mL. Therefore, a new and highly sensitive method based on RRS for the determination of CTS has been developed. Furthermore, the effect of molecular weight of CTS and the effect of the degree of deacetylation of CTS on the accurate quantification of CTS was studied. The experimental data was analyzed by linear regression analysis, which indicated that the molecular weight and the degree of deacetylation of CTS had no statistical significance and this method could be used to determine CTS accurately. Meanwhile, this assay was applied for CTS determination in health products with satisfactory results.

High-sensitivity determination of Zn(II) and Cu(II) in vitro by fluorescence polarization

NASA Astrophysics Data System (ADS)

Thompson, Richard B.; Maliwal, Badri P.; Feliccia, Vincent; Fierke, Carol A.

1998-04-01

Recent work has suggested that free Cu(II) may play a role in syndromes such as Crohn's and Wilson's diseases, as well as being a pollutant toxic at low levels to shellfish and sheep. Similarly, Zn(II) has been implicated in some neural damage in the brain resulting from epilepsy and ischemia. Several high sensitivity methods exist for determining these ions in solution, including GFAAS, ICP-MS, ICP-ES, and electrochemical techniques. However, these techniques are generally slow and costly, require pretreatment of the sample, require complex instruments and skilled personnel, and are incapable of imaging at the cellular and subcellular level. To address these shortcomings we developed fluorescence polarization (anisotropy) biosensing methods for these ions which are very sensitivity, highly selective, require simple instrumentation and little pretreatment, and are inexpensive. Thus free Cu(II) or Zn(II) can be determined at picomolar levels by changes in fluorescence polarization, lifetime, or wavelength ratio using these methods; these techniques may be adapted to microscopy.

Turning a low Q fiber resonator into a high-sensitivity displacement sensor using slow light concepts

NASA Astrophysics Data System (ADS)

Bravo, Mikel; Angulo-Vinuesa, Xabier; Martin-Lopez, Sonia; Lopez-Amo, Manuel; Gonzalez-Herraez, Miguel

2013-05-01

High-Q resonators have been widely used for sensing purposes. High Q factors normally lead to sharp spectral peaks which accordingly provide a strong sensitivity in spectral interrogation methods. In this work we employ a low-Q ring resonator to develop a high sensitivity sub-micrometric resolution displacement sensor. We use the slow-light effects occurring close to the critical coupling regime to achieve high sensitivity in the device. By tuning the losses in the cavity close to the critical coupling, extremely high group delay variations can be achieved, which in turn introduce strong enhancements of the absorption of the structure. We first validate the concept using an Optical Vector Analyzer (OVA) and then we propose a simple functional scheme for achieving a low-cost interrogation of this kind of sensors.

Demodulation method for tilted fiber Bragg grating refractometer with high sensitivity

NASA Astrophysics Data System (ADS)

Pham, Xuantung; Si, Jinhai; Chen, Tao; Wang, Ruize; Yan, Lihe; Cao, Houjun; Hou, Xun

2018-05-01

In this paper, we propose a demodulation method for refractive index (RI) sensing with tilted fiber Bragg gratings (TFBGs). It operates by monitoring the TFBG cladding mode resonance "cut-off wavelengths." The idea of a "cut-off wavelength" and its determination method are introduced. The RI sensitivities of TFBGs are significantly enhanced in certain RI ranges by using our demodulation method. The temperature-induced cross sensitivity is eliminated. We also demonstrate a parallel-double-angle TFBG (PDTFBG), in which two individual TFBGs are inscribed in the fiber core in parallel using a femtosecond laser and a phase mask. The RI sensing range of the PDTFBG is significantly broader than that of a conventional single-angle TFBG. In addition, its RI sensitivity can reach 1023.1 nm/refractive index unit in the 1.4401-1.4570 RI range when our proposed demodulation method is used.

Convenient, sensitive and high-throughput method for screening botanic origin.

PubMed

Yuan, Yuan; Jiang, Chao; Liu, Libing; Yu, Shulin; Cui, Zhanhu; Chen, Min; Lin, Shufang; Wang, Shu; Huang, Luqi

2014-06-23

In this work, a rapid (within 4-5 h), sensitive and visible new method for assessing botanic origin is developed by combining loop-mediated isothermal amplification with cationic conjugated polymers. The two Chinese medicinal materials (Jin-Yin-Hua and Shan-Yin-Hua) with similar morphology and chemical composition were clearly distinguished by gene SNP genotyping assays. The identification of plant species in Patented Chinese drugs containing Lonicera buds is successfully performed using this detection system. The method is also robust enough to be used in high-throughput screening. This new method is very helpful to identify herbal materials, and is beneficial for detecting safety and quality of botanic products.

Method for detecting the reactivity of chemicals towards peptides as an alternative test method for assessing skin sensitization potential.

PubMed

Cho, Sun-A; Jeong, Yun Hyeok; Kim, Ji Hoon; Kim, Seoyoung; Cho, Jun-Cheol; Heo, Yong; Heo, Young; Suh, Kyung-Do; Shin, Kyeho; An, Susun

2014-02-10

Cosmetics are normally composed of various ingredients. Some cosmetic ingredients can act as chemical haptens reacting toward proteins or peptides of human skin and they can provoke an immunologic reaction, called as skin sensitization. This haptenation process is very important step of inducing skin sensitization and evaluating the sensitizing potentials of cosmetic ingredients is very important for consumer safety. Therefore, animal alternative methods focusing on monitoring haptenation potential are undergoing vigorous research. To examine the further usefulness of spectrophotometric methods to monitor reactivity of chemicals toward peptides for cosmetic ingredients. Forty chemicals (25 sensitizers and 15 non-sensitizers) were reacted with 2 synthetic peptides, e.g., the cysteine peptides (Ac-RFAACAA-COOH) with free thiol group and the lysine peptides (Ac-RFAAKAA-COOH) with free amine group. Unreacted peptides can be detected after incubating with 5,5'-dithiobis-2-nitrobenzoic acid or fluorescamine™ as detection reagents for free thiol and amine group, respectively. Chemicals were categorized as sensitizers when they induced more than 10% depletion of cysteine peptides or more than 30% depletion of lysine peptides. The sensitivity, specificity, and accuracy were 80.0%, 86.7% and 82.5%, respectively. These results demonstrate that spectrophotometric methods can be an easy, fast, and high-throughput screening tools predicting the skin sensitization potential of chemical including cosmetic ingredient. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Temperature sensitive surfaces and methods of making same

DOEpatents

Liang, Liang [Richland, WA; Rieke, Peter C [Pasco, WA; Alford, Kentin L [Pasco, WA

2002-09-10

Poly-n-isopropylacrylamide surface coatings demonstrate the useful property of being able to switch charateristics depending upon temperature. More specifically, these coatings switch from being hydrophilic at low temperature to hydrophobic at high temperature. Research has been conducted for many years to better characterize and control the properties of temperature sensitive coatings. The present invention provides novel temperature sensitive coatings on articles and novel methods of making temperature sensitive coatings that are disposed on the surfaces of various articles. These novel coatings contain the reaction products of n-isopropylacrylamide and are characterized by their properties such as advancing contact angles. Numerous other characteristics such as coating thickness, surface roughness, and hydrophilic-to-hydrophobic transition temperatures are also described. The present invention includes articles having temperature-sensitve coatings with improved properties as well as improved methods for forming temperature sensitive coatings.

Development of a highly sensitive and specific enzyme-linked immunosorbent assay (ELISA) for the detection of phenylethanolamine A in tissue and feed samples and confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS).

PubMed

Cao, Biyun; He, Guangzhao; Yang, Hong; Chang, Huafang; Li, Shuqun; Deng, Anping

2013-10-15

Phenylethanolamine A (PA) is a new emerged β-adrenergic agonist illegally used as feed additives for growth promotion. In this study, a highly sensitive and specific indirect competitive enzyme-linked immunosorbent assay (ELISA) for the detection of PA in tissue and feed samples was developed and confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS). By reduction of nitryl group to amino group, the PA derivative was synthesized and coupled to carrier proteins with diazobenzidine method. The antisera obtained from four immunized rabbits were characterized in terms of sensitivity and specificity. All antisera displayed high sensitivity with IC50 values lower than 0.48 ng mL(-1). The most sensitive ELISA was established with IC50 and limit of detection (LOD) values of 0.049 ng mL(-1) and 0.003 ng mL(-1), respectively. The cross-reactivity (CR) values of the antisera with three frequently used β-adrenergic agonists (clenbuterol, salbutamol and ractopamine) were lesser than 0.39%; there was no CR of the antisera with other six compounds including two structurally related substances (isoproterenol, phenylephrine). To investigate the accuracy and precision of the assay, swine kidney, liver, meat and feed samples were fortified with PA at different content and analyzed by ELISA. Acceptable recovery rates of 92.2-113.7% and intra-assay coefficients of variation of 3.8-10.9% (n=3) were achieved. Seven spiked samples were simultaneously analyzed by ELISA and LC-MS/MS. There was a high correlation coefficient of 0.9956 (n=7) between the two methods. The proposed ELISA proven to be a feasible quantitative/screening method for PA analysis in tissue and feed samples with the properties of high sensitivity and specificity, high sample throughput and low expensive. © 2013 Elsevier B.V. All rights reserved.

Searching for the full symphony of black hole binary mergers

NASA Astrophysics Data System (ADS)

Harry, Ian; Bustillo, Juan Calderón; Nitz, Alex

2018-01-01

Current searches for the gravitational-wave signature of compact binary mergers rely on matched-filtering data from interferometric observatories with sets of modeled gravitational waveforms. These searches currently use model waveforms that do not include the higher-order mode content of the gravitational-wave signal. Higher-order modes are important for many compact binary mergers and their omission reduces the sensitivity to such sources. In this work we explore the sensitivity loss incurred from omitting higher-order modes. We present a new method for searching for compact binary mergers using waveforms that include higher-order mode effects, and evaluate the sensitivity increase that using our new method would allow. We find that, when evaluating sensitivity at a constant rate-of-false alarm, and when including the fact that signal-consistency tests can reject some signals that include higher-order mode content, we observe a sensitivity increase of up to a factor of 2 in volume for high mass ratio, high total-mass systems. For systems with equal mass, or with total mass ˜50 M⊙, we see more modest sensitivity increases, <10 %, which indicates that the existing search is already performing well. Our new search method is also directly applicable in searches for generic compact binaries.

Three Minute Method for Amino Acid Analysis by UHPLC and high resolution quadrupole orbitrap mass spectrometry

PubMed Central

Nemkov, Travis; D'Alessandro, Angelo; Hansen, Kirk C.

2015-01-01

Amino acid analysis is a powerful bioanalytical technique for many biomedical research endeavors, including cancer, emergency medicine, nutrition and neuroscience research. In the present study, we present a three minute analytical method for underivatized amino acid analysis that employs ultra-high performance liquid chromatography and high resolution quadrupole orbitrap mass spectrometry. This method has demonstrated linearity (mM to nM range), reproducibility (intra-day<5%, inter-day<20%), sensitivity (low fmol) and selectivity. Here, we illustrate the rapidity and accuracy of the method through comparison with conventional liquid chromatography-mass spectrometry methods. We further demonstrate the robustness and sensitivity of this method on a diverse range of biological matrices. Using this method we were able to selectively discriminate murine pancreatic cancer cells with and without knocked down expression of Hypoxia Inducible Factor 1α; plasma, lymph and bronchioalveolar lavage fluid samples from control versus hemorrhaged rats; and muscle tissue samples harvested from rats subjected to both low fat and high fat diets. Furthermore, we were able to exploit the sensitivity of the method to detect and quantify the release of glutamate from sparsely isolated murine taste buds. Spiked in light or heavy standards (13C6-arginine, 13C6-lysine, 13C515N2-glutamine) or xenometabolites were used to determine coefficient of variations, confirm linearity of relative quantitation in four different matrices, and overcome matrix effects for absolute quantitation. The presented method enables high-throughput analysis of low abundance samples requiring only one percent of the material extracted from 100,000 cells, 10 μl of biological fluid, or 2 mg of muscle tissue. PMID:26058356

Resonance-induced sensitivity enhancement method for conductivity sensors

NASA Technical Reports Server (NTRS)

Tai, Yu-Chong (Inventor); Shih, Chi-yuan (Inventor); Li, Wei (Inventor); Zheng, Siyang (Inventor)

2009-01-01

Methods and systems for improving the sensitivity of a variety of conductivity sensing devices, in particular capacitively-coupled contactless conductivity detectors. A parallel inductor is added to the conductivity sensor. The sensor with the parallel inductor is operated at a resonant frequency of the equivalent circuit model. At the resonant frequency, parasitic capacitances that are either in series or in parallel with the conductance (and possibly a series resistance) is substantially removed from the equivalent circuit, leaving a purely resistive impedance. An appreciably higher sensor sensitivity results. Experimental verification shows that sensitivity improvements of the order of 10,000-fold are possible. Examples of detecting particulates with high precision by application of the apparatus and methods of operation are described.

First- and Second-Order Sensitivity Analysis of a P-Version Finite Element Equation Via Automatic Differentiation

NASA Technical Reports Server (NTRS)

Hou, Gene

1998-01-01

Sensitivity analysis is a technique for determining derivatives of system responses with respect to design parameters. Among many methods available for sensitivity analysis, automatic differentiation has been proven through many applications in fluid dynamics and structural mechanics to be an accurate and easy method for obtaining derivatives. Nevertheless, the method can be computational expensive and can require a high memory space. This project will apply an automatic differentiation tool, ADIFOR, to a p-version finite element code to obtain first- and second- order then-nal derivatives, respectively. The focus of the study is on the implementation process and the performance of the ADIFOR-enhanced codes for sensitivity analysis in terms of memory requirement, computational efficiency, and accuracy.

Accelerated Sensitivity Analysis in High-Dimensional Stochastic Reaction Networks

PubMed Central

Arampatzis, Georgios; Katsoulakis, Markos A.; Pantazis, Yannis

2015-01-01

Existing sensitivity analysis approaches are not able to handle efficiently stochastic reaction networks with a large number of parameters and species, which are typical in the modeling and simulation of complex biochemical phenomena. In this paper, a two-step strategy for parametric sensitivity analysis for such systems is proposed, exploiting advantages and synergies between two recently proposed sensitivity analysis methodologies for stochastic dynamics. The first method performs sensitivity analysis of the stochastic dynamics by means of the Fisher Information Matrix on the underlying distribution of the trajectories; the second method is a reduced-variance, finite-difference, gradient-type sensitivity approach relying on stochastic coupling techniques for variance reduction. Here we demonstrate that these two methods can be combined and deployed together by means of a new sensitivity bound which incorporates the variance of the quantity of interest as well as the Fisher Information Matrix estimated from the first method. The first step of the proposed strategy labels sensitivities using the bound and screens out the insensitive parameters in a controlled manner. In the second step of the proposed strategy, a finite-difference method is applied only for the sensitivity estimation of the (potentially) sensitive parameters that have not been screened out in the first step. Results on an epidermal growth factor network with fifty parameters and on a protein homeostasis with eighty parameters demonstrate that the proposed strategy is able to quickly discover and discard the insensitive parameters and in the remaining potentially sensitive parameters it accurately estimates the sensitivities. The new sensitivity strategy can be several times faster than current state-of-the-art approaches that test all parameters, especially in “sloppy” systems. In particular, the computational acceleration is quantified by the ratio between the total number of parameters over the number of the sensitive parameters. PMID:26161544

Evaluation and comparison of statistical methods for early temporal detection of outbreaks: A simulation-based study

PubMed Central

Le Strat, Yann

2017-01-01

The objective of this paper is to evaluate a panel of statistical algorithms for temporal outbreak detection. Based on a large dataset of simulated weekly surveillance time series, we performed a systematic assessment of 21 statistical algorithms, 19 implemented in the R package surveillance and two other methods. We estimated false positive rate (FPR), probability of detection (POD), probability of detection during the first week, sensitivity, specificity, negative and positive predictive values and F1-measure for each detection method. Then, to identify the factors associated with these performance measures, we ran multivariate Poisson regression models adjusted for the characteristics of the simulated time series (trend, seasonality, dispersion, outbreak sizes, etc.). The FPR ranged from 0.7% to 59.9% and the POD from 43.3% to 88.7%. Some methods had a very high specificity, up to 99.4%, but a low sensitivity. Methods with a high sensitivity (up to 79.5%) had a low specificity. All methods had a high negative predictive value, over 94%, while positive predictive values ranged from 6.5% to 68.4%. Multivariate Poisson regression models showed that performance measures were strongly influenced by the characteristics of time series. Past or current outbreak size and duration strongly influenced detection performances. PMID:28715489

Development of a cyclic voltammetry method for the detection of Clostridium novyi in black disease.

PubMed

Liu, L L; Jiang, D N; Xiang, G M; Liu, C; Yu, J C; Pu, X Y

2014-03-17

Black disease is an acute disease of sheep and cattle. The pathogen is the obligate anaerobe, Clostridium novyi. Due to difficulties of anaerobic culturing in the country or disaster sites, a simple, rapid, and sensitive method is required. In this study, an electrochemical method, the cyclic voltammetry method, basing on loop-mediated isothermal amplification (LAMP), electrochemical ion bonding (positive dye, methylene blue), was introduced. DNA extracted from C. novyi specimens was amplified through the LAMP reaction. Then the products combined were with methylene blue, which lead to a reduction in the oxidation peak current (ipA) and the reduction peak current (ipC) of the cyclic voltammetry. The changes of ipA/ipC were real-time measured by special designed electrode, so the DNA was quantitatively detected. The results displayed that this electrochemical detection of C. novyi could be completed in 1-2 h with the lowest bacterial concentration of 10(2) colony forming units/mL, and high accuracy (96.5%), sensitivity (96%), and specificity (97%) compared to polymerase chain reation. The cyclic voltammetry method was a simple and fast method, with high sensitivity and high specificity, and has great potential to be a usable molecular tool for fast diagnosis of Black disease.

Highly sensitive measurement of whole blood chromium by inductively coupled plasma mass spectrometry.

PubMed

Cieslak, Wendy; Pap, Kathleen; Bunch, Dustin R; Reineks, Edmunds; Jackson, Raymond; Steinle, Roxanne; Wang, Sihe

2013-02-01

Chromium (Cr), a trace metal element, is implicated in diabetes and cardiovascular disease. A hypochromic state has been associated with poor blood glucose control and unfavorable lipid metabolism. Sensitive and accurate measurement of blood chromium is very important to assess the chromium nutritional status. However, interferents in biological matrices and contamination make the sensitive analysis challenging. The primary goal of this study was to develop a highly sensitive method for quantification of total Cr in whole blood by inductively coupled plasma mass spectrometry (ICP-MS) and to validate the reference interval in a local healthy population. This method was developed on an ICP-MS with a collision/reaction cell. Interference was minimized using both kinetic energy discrimination between the quadrupole and hexapole and a selective collision gas (helium). Reference interval was validated in whole blood samples (n=51) collected in trace element free EDTA tubes from healthy adults (12 males, 39 females), aged 19-64 years (38.8±12.6), after a minimum of 8 h fasting. Blood samples were aliquoted into cryogenic vials and stored at -70 °C until analysis. The assay linearity was 3.42 to 1446.59 nmol/L with an accuracy of 87.7 to 99.8%. The high sensitivity was achieved by minimization of interference through selective kinetic energy discrimination and selective collision using helium. The reference interval for total Cr using a non-parametric method was verified to be 3.92 to 7.48 nmol/L. This validated ICP-MS methodology is highly sensitive and selective for measuring total Cr in whole blood. Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. Published by Elsevier Inc. All rights reserved.

Sensitivity and specificity of the method used for ascertainment of healthcare-associated infections in the second Slovenian national prevalence survey.

PubMed

Serdt, Mojca; Lejko Zupanc, Tatjana; Korošec, Aleš; Klavs, Irena

2016-12-01

The second Slovenian national healthcare-associated infections (HAIs) prevalence survey (SNHPS) was conducted in acute-care hospitals in 2011. The objective was to assess the sensitivity and specificity of the method used for the ascertainment of six types of HAIs (bloodstream infections, catheter-associated infections, lower respiratory tract infections, pneumoniae, surgical site infections, and urinary tract infections) in the University Medical Centre Ljubljana (UMCL). A cross-sectional study was conducted in patients surveyed in the SNHPS in the UMCL using a retrospective medical chart review (RMCR) and European HAIs surveillance definitions. Sensitivity and specificity of the method used in the SNHPS using RMCR as a reference was computed for ascertainment of patients with any of the six selected types of HAIs and for individual types of HAIs. Agreement between the SNHPS and RMCR results was analyzed using Cohen's kappa coefficient. 1474 of 1742 (84.6%) patients surveyed in the SNHPS were included in RMCR. The sensitivity of the SNHPS method for detecting any of six HAIs was 90% (95% confidence interval (CI): 81%-95%) and specificity 99% (95% CI: 98%-99%). The sensitivity by type of HAI ranged from 63% (lower respiratory tract infections) to 92% (bloodstream infections). Specificity was at least 99% for all types of HAIs. Agreement between the two data collection approaches for HAIs overall was very good (κ=0.83). The overall sensitivity of SNHPS collection method for ascertaining HAIs overall was high and the specificity was very high. This suggests that the estimated prevalence of HAIs in the SNHPS was credible.

HSQC-1,n-ADEQUATE: a new approach to long-range 13C-13C correlation by covariance processing.

PubMed

Martin, Gary E; Hilton, Bruce D; Willcott, M Robert; Blinov, Kirill A

2011-10-01

Long-range, two-dimensional heteronuclear shift correlation NMR methods play a pivotal role in the assembly of novel molecular structures. The well-established GHMBC method is a high-sensitivity mainstay technique, affording connectivity information via (n)J(CH) coupling pathways. Unfortunately, there is no simple way of determining the value of n and hence no way of differentiating two-bond from three- and occasionally four-bond correlations. Three-bond correlations, however, generally predominate. Recent work has shown that the unsymmetrical indirect covariance or generalized indirect covariance processing of multiplicity edited GHSQC and 1,1-ADEQUATE spectra provides high-sensitivity access to a (13)C-(13) C connectivity map in the form of an HSQC-1,1-ADEQUATE spectrum. Covariance processing of these data allows the 1,1-ADEQUATE connectivity information to be exploited with the inherent sensitivity of the GHSQC spectrum rather than the intrinsically lower sensitivity of the 1,1-ADEQUATE spectrum itself. Data acquisition times and/or sample size can be substantially reduced when covariance processing is to be employed. In an extension of that work, 1,n-ADEQUATE spectra can likewise be subjected to covariance processing to afford high-sensitivity access to the equivalent of (4)J(CH) GHMBC connectivity information. The method is illustrated using strychnine as a model compound. Copyright © 2011 John Wiley & Sons, Ltd.

Results of an integrated structure-control law design sensitivity analysis

NASA Technical Reports Server (NTRS)

Gilbert, Michael G.

1988-01-01

Next generation air and space vehicle designs are driven by increased performance requirements, demanding a high level of design integration between traditionally separate design disciplines. Interdisciplinary analysis capabilities have been developed, for aeroservoelastic aircraft and large flexible spacecraft control for instance, but the requisite integrated design methods are only beginning to be developed. One integrated design method which has received attention is based on hierarchal problem decompositions, optimization, and design sensitivity analyses. This paper highlights a design sensitivity analysis method for Linear Quadratic Cost, Gaussian (LQG) optimal control laws, which predicts change in the optimal control law due to changes in fixed problem parameters using analytical sensitivity equations. Numerical results of a design sensitivity analysis for a realistic aeroservoelastic aircraft example are presented. In this example, the sensitivity of the optimally controlled aircraft's response to various problem formulation and physical aircraft parameters is determined. These results are used to predict the aircraft's new optimally controlled response if the parameter was to have some other nominal value during the control law design process. The sensitivity results are validated by recomputing the optimal control law for discrete variations in parameters, computing the new actual aircraft response, and comparing with the predicted response. These results show an improvement in sensitivity accuracy for integrated design purposes over methods which do not include changess in the optimal control law. Use of the analytical LQG sensitivity expressions is also shown to be more efficient that finite difference methods for the computation of the equivalent sensitivity information.

Automatic high-sensitivity control of suspended pollutants in drinking and natural water

NASA Astrophysics Data System (ADS)

Akopov, Edmund I.; Karabegov, M.; Ovanesyan, A.

1993-11-01

This article presents a description of the new instrumental method and device for automatic measurement of water turbidity (WT) by means of photoelectron flow ultramicroscope (PFU). The method presents the WT determination by measuring the number concentration (number of particles suspended in 1 cm3 of water under study) using the PFU and demonstrates much higher sensitivity and accuracy in comparison with the usual methods--turbidimetry and nephelometry.

Label-Free Electrical Immunosensor for Highly Sensitive and Specific Detection of Microcystin-LR in Water Samples.

PubMed

Tan, Feng; Saucedo, Nuvia Maria; Ramnani, Pankaj; Mulchandani, Ashok

2015-08-04

Microcystin-LR (MCLR) is one of the most commonly detected and toxic cyclic heptapeptide cyanotoxins released by cyanobacterial blooms in surface waters, for which sensitive and specific detection methods are necessary to carry out its recognition and quantification. Here, we present a single-walled carbon nanotube (SWCNTs)-based label-free chemiresistive immunosensor for highly sensitive and specific detection of MCLR in different source waters. MCLR was initially immobilized on SWCNTs modified interdigitated electrode, followed by incubation with monoclonal anti-MCLR antibody. The competitive binding of MCLR in sample solutions induced departure of the antibody from the antibody-antigen complexes formed on SWCNTs, resulting in change in the conductivity between source and drain of the sensor. The displacement assay greatly improved the sensitivity of the sensor compared with direct immunoassay on the same device. The immunosensor exhibited a wide linear response to log value of MCLR concentration ranging from 1 to 1000 ng/L, with a detection limit of 0.6 ng/L. This method showed good reproducibility, stability and recovery. The proposed method provides a powerful tool for rapid and sensitive monitoring of MCLR in environmental samples.

New sensitive high-performance liquid chromatography-tandem mass spectrometry method for the detection of horse and pork in halal beef.

PubMed

von Bargen, Christoph; Dojahn, Jörg; Waidelich, Dietmar; Humpf, Hans-Ulrich; Brockmeyer, Jens

2013-12-11

The accidental or fraudulent blending of meat from different species is a highly relevant aspect for food product quality control, especially for consumers with ethical concerns against species, such as horse or pork. In this study, we present a sensitive mass spectrometrical approach for the detection of trace contaminations of horse meat and pork and demonstrate the specificity of the identified biomarker peptides against chicken, lamb, and beef. Biomarker peptides were identified by a shotgun proteomic approach using tryptic digests of protein extracts and were verified by the analysis of 21 different meat samples from the 5 species included in this study. For the most sensitive peptides, a multiple reaction monitoring (MRM) method was developed that allows for the detection of 0.55% horse or pork in a beef matrix. To enhance sensitivity, we applied MRM(3) experiments and were able to detect down to 0.13% pork contamination in beef. To the best of our knowledge, we present here the first rapid and sensitive mass spectrometrical method for the detection of horse and pork by use of MRM and MRM(3).

Highly sensitive distributed birefringence measurements based on a two-pulse interrogation of a dynamic Brillouin grating

NASA Astrophysics Data System (ADS)

Soto, Marcelo A.; Denisov, Andrey; Angulo-Vinuesa, Xabier; Martin-Lopez, Sonia; Thévenaz, Luc; Gonzalez-Herraez, Miguel

2017-04-01

A method for distributed birefringence measurements is proposed based on the interference pattern generated by the interrogation of a dynamic Brillouin grating (DBG) using two short consecutive optical pulses. Compared to existing DBG interrogation techniques, the method here offers an improved sensitivity to birefringence changes thanks to the interferometric effect generated by the reflections of the two pulses. Experimental results demonstrate the possibility to obtain the longitudinal birefringence profile of a 20 m-long Panda fibre with an accuracy of 10-8 using 16 averages and 30 cm spatial resolution. The method enables sub-metric and highly-accurate distributed temperature and strain sensing.

Sensitivity Enhancement of FBG-Based Strain Sensor.

PubMed

Li, Ruiya; Chen, Yiyang; Tan, Yuegang; Zhou, Zude; Li, Tianliang; Mao, Jian

2018-05-17

A novel fiber Bragg grating (FBG)-based strain sensor with a high-sensitivity is presented in this paper. The proposed FBG-based strain sensor enhances sensitivity by pasting the FBG on a substrate with a lever structure. This typical mechanical configuration mechanically amplifies the strain of the FBG to enhance overall sensitivity. As this mechanical configuration has a high stiffness, the proposed sensor can achieve a high resonant frequency and a wide dynamic working range. The sensing principle is presented, and the corresponding theoretical model is derived and validated. Experimental results demonstrate that the developed FBG-based strain sensor achieves an enhanced strain sensitivity of 6.2 pm/με, which is consistent with the theoretical analysis result. The strain sensitivity of the developed sensor is 5.2 times of the strain sensitivity of a bare fiber Bragg grating strain sensor. The dynamic characteristics of this sensor are investigated through the finite element method (FEM) and experimental tests. The developed sensor exhibits an excellent strain-sensitivity-enhancing property in a wide frequency range. The proposed high-sensitivity FBG-based strain sensor can be used for small-amplitude micro-strain measurement in harsh industrial environments.

Sensitivity Enhancement of FBG-Based Strain Sensor

PubMed Central

Chen, Yiyang; Tan, Yuegang; Zhou, Zude; Mao, Jian

2018-01-01

A novel fiber Bragg grating (FBG)-based strain sensor with a high-sensitivity is presented in this paper. The proposed FBG-based strain sensor enhances sensitivity by pasting the FBG on a substrate with a lever structure. This typical mechanical configuration mechanically amplifies the strain of the FBG to enhance overall sensitivity. As this mechanical configuration has a high stiffness, the proposed sensor can achieve a high resonant frequency and a wide dynamic working range. The sensing principle is presented, and the corresponding theoretical model is derived and validated. Experimental results demonstrate that the developed FBG-based strain sensor achieves an enhanced strain sensitivity of 6.2 pm/με, which is consistent with the theoretical analysis result. The strain sensitivity of the developed sensor is 5.2 times of the strain sensitivity of a bare fiber Bragg grating strain sensor. The dynamic characteristics of this sensor are investigated through the finite element method (FEM) and experimental tests. The developed sensor exhibits an excellent strain-sensitivity-enhancing property in a wide frequency range. The proposed high-sensitivity FBG-based strain sensor can be used for small-amplitude micro-strain measurement in harsh industrial environments. PMID:29772826

Low-Cost and Rapid Fabrication of Metallic Nanostructures for Sensitive Biosensors Using Hot-Embossing and Dielectric-Heating Nanoimprint Methods

PubMed Central

Lee, Kuang-Li; Wu, Tsung-Yeh; Hsu, Hsuan-Yeh; Yang, Sen-Yeu; Wei, Pei-Kuen

2017-01-01

We propose two approaches—hot-embossing and dielectric-heating nanoimprinting methods—for low-cost and rapid fabrication of periodic nanostructures. Each nanofabrication process for the imprinted plastic nanostructures is completed within several seconds without the use of release agents and epoxy. Low-cost, large-area, and highly sensitive aluminum nanostructures on A4 size plastic films are fabricated by evaporating aluminum film on hot-embossing nanostructures. The narrowest bandwidth of the Fano resonance is only 2.7 nm in the visible light region. The periodic aluminum nanostructure achieves a figure of merit of 150, and an intensity sensitivity of 29,345%/RIU (refractive index unit). The rapid fabrication is also achieved by using radio-frequency (RF) sensitive plastic films and a commercial RF welding machine. The dielectric-heating, using RF power, takes advantage of the rapid heating/cooling process and lower electric power consumption. The fabricated capped aluminum nanoslit array has a 5 nm Fano linewidth and 490.46 nm/RIU wavelength sensitivity. The biosensing capabilities of the metallic nanostructures are further verified by measuring antigen–antibody interactions using bovine serum albumin (BSA) and anti-BSA. These rapid and high-throughput fabrication methods can benefit low-cost, highly sensitive biosensors and other sensing applications. PMID:28671600

Panel-based Genetic Diagnostic Testing for Inherited Eye Diseases is Highly Accurate and Reproducible and More Sensitive for Variant Detection Than Exome Sequencing

PubMed Central

Bujakowska, Kinga M.; Sousa, Maria E.; Fonseca-Kelly, Zoë D.; Taub, Daniel G.; Janessian, Maria; Wang, Dan Yi; Au, Elizabeth D.; Sims, Katherine B.; Sweetser, David A.; Fulton, Anne B.; Liu, Qin; Wiggs, Janey L.; Gai, Xiaowu; Pierce, Eric A.

2015-01-01

Purpose Next-generation sequencing (NGS) based methods are being adopted broadly for genetic diagnostic testing, but the performance characteristics of these techniques have not been fully defined with regard to test accuracy and reproducibility. Methods We developed a targeted enrichment and NGS approach for genetic diagnostic testing of patients with inherited eye disorders, including inherited retinal degenerations, optic atrophy and glaucoma. In preparation for providing this Genetic Eye Disease (GEDi) test on a CLIA-certified basis, we performed experiments to measure the sensitivity, specificity, reproducibility as well as the clinical sensitivity of the test. Results The GEDi test is highly reproducible and accurate, with sensitivity and specificity for single nucleotide variant detection of 97.9% and 100%, respectively. The sensitivity for variant detection was notably better than the 88.3% achieved by whole exome sequencing (WES) using the same metrics, due to better coverage of targeted genes in the GEDi test compared to commercially available exome capture sets. Prospective testing of 192 patients with IRDs indicated that the clinical sensitivity of the GEDi test is high, with a diagnostic rate of 51%. Conclusion The data suggest that based on quantified performance metrics, selective targeted enrichment is preferable to WES for genetic diagnostic testing. PMID:25412400

Competitive amplification of differentially melting amplicons (CADMA) enables sensitive and direct detection of all mutation types by high-resolution melting analysis.

PubMed

Kristensen, Lasse S; Andersen, Gitte B; Hager, Henrik; Hansen, Lise Lotte

2012-01-01

Sensitive and specific mutation detection is of particular importance in cancer diagnostics, prognostics, and individualized patient treatment. However, the majority of molecular methodologies that have been developed with the aim of increasing the sensitivity of mutation testing have drawbacks in terms of specificity, convenience, or costs. Here, we have established a new method, Competitive Amplification of Differentially Melting Amplicons (CADMA), which allows very sensitive and specific detection of all mutation types. The principle of the method is to amplify wild-type and mutated sequences simultaneously using a three-primer system. A mutation-specific primer is designed to introduce melting temperature decreasing mutations in the resulting mutated amplicon, while a second overlapping primer is designed to amplify both wild-type and mutated sequences. When combined with a third common primer very sensitive mutation detection becomes possible, when using high-resolution melting (HRM) as detection platform. The introduction of melting temperature decreasing mutations in the mutated amplicon also allows for further mutation enrichment by fast coamplification at lower denaturation temperature PCR (COLD-PCR). For proof-of-concept, we have designed CADMA assays for clinically relevant BRAF, EGFR, KRAS, and PIK3CA mutations, which are sensitive to, between 0.025% and 0.25%, mutated alleles in a wild-type background. In conclusion, CADMA enables highly sensitive and specific mutation detection by HRM analysis. © 2011 Wiley Periodicals, Inc.

A Highly Sensitive Nonenzymatic Glucose Biosensor Based on the Regulatory Effect of Glucose on Electrochemical Behaviors of Colloidal Silver Nanoparticles on MoS₂†.

PubMed

Anderson, Kash; Poulter, Benjamin; Dudgeon, John; Li, Shu-En; Ma, Xiang

2017-08-05

A novel and highly sensitive nonenzymatic glucose biosensor was developed by nucleating colloidal silver nanoparticles (AgNPs) on MoS₂. The facile fabrication method, high reproducibility (97.5%) and stability indicates a promising capability for large-scale manufacturing. Additionally, the excellent sensitivity (9044.6 μA mM -1 cm -2 ), low detection limit (0.03 μM), appropriate linear range of 0.1-1000 μM, and high selectivity suggests that this biosensor has a great potential to be applied for noninvasive glucose detection in human body fluids, such as sweat and saliva.

Sensitivity of different Trypanosoma vivax specific primers for the diagnosis of livestock trypanosomosis using different DNA extraction methods.

PubMed

Gonzales, J L; Loza, A; Chacon, E

2006-03-15

There are several T. vivax specific primers developed for PCR diagnosis. Most of these primers were validated under different DNA extraction methods and study designs leading to heterogeneity of results. The objective of the present study was to validate PCR as a diagnostic test for T. vivax trypanosomosis by means of determining the test sensitivity of different published specific primers with different sample preparations. Four different DNA extraction methods were used to test the sensitivity of PCR with four different primer sets. DNA was extracted directly from whole blood samples, blood dried on filter papers or blood dried on FTA cards. The results showed that the sensitivity of PCR with each primer set was highly dependant of the sample preparation and DNA extraction method. The highest sensitivities for all the primers tested were determined using DNA extracted from whole blood samples, while the lowest sensitivities were obtained when DNA was extracted from filter paper preparations. To conclude, the obtained results are discussed and a protocol for diagnosis and surveillance for T. vivax trypanosomosis is recommended.

Field Demonstration of a Multiplexed Point-of-Care Diagnostic Platform for Plant Pathogens.

PubMed

Lau, Han Yih; Wang, Yuling; Wee, Eugene J H; Botella, Jose R; Trau, Matt

2016-08-16

Effective disease management strategies to prevent catastrophic crop losses require rapid, sensitive, and multiplexed detection methods for timely decision making. To address this need, a rapid, highly specific and sensitive point-of-care method for multiplex detection of plant pathogens was developed by taking advantage of surface-enhanced Raman scattering (SERS) labeled nanotags and recombinase polymerase amplification (RPA), which is a rapid isothermal amplification method with high specificity. In this study, three agriculturally important plant pathogens (Botrytis cinerea, Pseudomonas syringae, and Fusarium oxysporum) were used to demonstrate potential translation into the field. The RPA-SERS method was faster, more sensitive than polymerase chain reaction, and could detect as little as 2 copies of B. cinerea DNA. Furthermore, multiplex detection of the three pathogens was demonstrated for complex systems such as the Arabidopsis thaliana plant and commercial tomato crops. To demonstrate the potential for on-site field applications, a rapid single-tube RPA/SERS assay was further developed and successfully performed for a specific target outside of a laboratory setting.

Development of a Sensitive Luciferase-Based Sandwich ELISA System for the Detection of Human Extracellular Matrix 1 Protein.

PubMed

Li, Ya; Li, Yanqing; Zhao, Junli; Zheng, Xiaojing; Mao, Qinwen; Xia, Haibin

2016-12-01

Enzyme-linked immunosorbent assay (ELISA) has been one of the main methods for detecting an antigen in an aqueous sample for more than four decades. Nowadays, one of the biggest concerns for ELISA is still how to improve the sensitivity of the assay, and the luciferase-luciferin reaction system has been noticed as a new detection method with high sensitivity. In this study, a luciferin-luciferase reaction system was used as the detection method for a sandwich ELISA system. It was shown that this new system led to an increase in the detection sensitivity of at least two times when compared with the traditional horseradish peroxidase (HRP) detection method. Lastly, the serum levels of the human extracellular matrix 1 protein of breast cancer patients were determined by the new system, which were overall similar to the HRP chemiluminescent system. Furthermore, this new luciferase reporter can be implemented into other ELISA systems for the purpose of increasing the assay sensitivity.

A Highly Sensitive Method for Quantitative Determination of Abscisic Acid 1

PubMed Central

Michler, Charles H.; Lineberger, R. Daniel; Chism, Grady W.

1986-01-01

An abscisic acid derivative was formed by reaction with pentafluorobenzyl bromide which allowed highly sensitive detection by gas-liquid chromatography with electron capture detection. In comparison to the methyl ester derivative, the pentafluorobenzyl derivative of abscisic acid was four times more sensitive to electron capture detection and was stable at room temperature in the presence of ultraviolet light. Derivatization was rapid and the molecular weight of the new compound was confirmed by gas-liquid chromatography-mass spectrometry. PMID:16665076

Method Of Signal Amplification In Multi-Chromophore Luminescence Sensors

DOEpatents

Levitsky, Igor A.; Krivoshlykov, Sergei G.

2004-02-03

A fluorescence-based method for highly sensitive and selective detection of analyte molecules is proposed. The method employs the energy transfer between two or more fluorescent chromophores in a carefully selected polymer matrix. In one preferred embodiment, signal amplification has been achieved in the fluorescent sensing of dimethyl methylphosphonate (DMMP) using two dyes, 3-aminofluoranthene (AM) and Nile Red (NR), in a hydrogen bond acidic polymer matrix. The selected polymer matrix quenches the fluorescence of both dyes and shifts dye emission and absorption spectra relative to more inert matrices. Upon DMMP sorption, the AM fluorescence shifts to the red at the same time the NR absorption shifts to the blue, resulting in better band overlap and increased energy transfer between chromophores. In another preferred embodiment, the sensitive material is incorporated into an optical fiber system enabling efficient excitation of the dye and collecting the fluorescent signal form the sensitive material on the remote end of the system. The proposed method can be applied to multichromophore luminescence sensor systems incorporating N-chromophores leading to N-fold signal amplification and improved selectivity. The method can be used in all applications where highly sensitive detection of basic gases, such as dimethyl methylphosphonate (DMMP), Sarin, Soman and other chemical warfare agents having basic properties, is required, including environmental monitoring, chemical industry and medicine.

A cable-driven parallel manipulator with force sensing capabilities for high-accuracy tissue endomicroscopy.

PubMed

Miyashita, Kiyoteru; Oude Vrielink, Timo; Mylonas, George

2018-05-01

Endomicroscopy (EM) provides high resolution, non-invasive histological tissue information and can be used for scanning of large areas of tissue to assess cancerous and pre-cancerous lesions and their margins. However, current robotic solutions do not provide the accuracy and force sensitivity required to perform safe and accurate tissue scanning. A new surgical instrument has been developed that uses a cable-driven parallel mechanism (CPDM) to manipulate an EM probe. End-effector forces are determined by measuring the tensions in each cable. As a result, the instrument allows to accurately apply a contact force on a tissue, while at the same time offering high resolution and highly repeatable probe movement. 0.2 and 0.6 N force sensitivities were found for 1 and 2 DoF image acquisition methods, respectively. A back-stepping technique can be used when a higher force sensitivity is required for the acquisition of high quality tissue images. This method was successful in acquiring images on ex vivo liver tissue. The proposed approach offers high force sensitivity and precise control, which is essential for robotic EM. The technical benefits of the current system can also be used for other surgical robotic applications, including safe autonomous control, haptic feedback and palpation.

Ag Nanoparticles-enhanced Fluorescence of Terbium-Deferasirox Complexes for the Highly Sensitive Determination of Deferasirox.

PubMed

Abolhasani, Jafar; Naderali, Roza; Hassanzadeh, Javad

2016-01-01

We describe the effect of different sized gold and silver nanoparticles on the terbium sensitized fluorescence of deferasirox. It is indicated that silver nanostructures, especially 18 nm Ag nanoparticles (AgNPs), have a remarkable amplifying effect compared to Au nanoparticles. Based on this observation, a highly sensitive and selective method was developed for the determination of deferasirox. Effects of various parameters like AgNPs and Tb(3+) concentration and pH of media were investigated. Under the optimal conditions, a calibration curve was plotted as the fluorescence intensities versus the concentration of deferasirox in the range of 0.1 to 200 nmol L(-1), and detection limit of 0.03 nmol L(-1) was obtained. The method has good linearity, recovery, reproducibility and sensitivity, and was satisfactorily applied for the determination of deferasirox in urine and pharmaceutical samples.

Case-Deletion Diagnostics for Maximum Likelihood Multipoint Quantitative Trait Locus Linkage Analysis

PubMed Central

Mendoza, Maria C.B.; Burns, Trudy L.; Jones, Michael P.

2009-01-01

Objectives Case-deletion diagnostic methods are tools that allow identification of influential observations that may affect parameter estimates and model fitting conclusions. The goal of this paper was to develop two case-deletion diagnostics, the exact case deletion (ECD) and the empirical influence function (EIF), for detecting outliers that can affect results of sib-pair maximum likelihood quantitative trait locus (QTL) linkage analysis. Methods Subroutines to compute the ECD and EIF were incorporated into the maximum likelihood QTL variance estimation components of the linkage analysis program MAPMAKER/SIBS. Performance of the diagnostics was compared in simulation studies that evaluated the proportion of outliers correctly identified (sensitivity), and the proportion of non-outliers correctly identified (specificity). Results Simulations involving nuclear family data sets with one outlier showed EIF sensitivities approximated ECD sensitivities well for outlier-affected parameters. Sensitivities were high, indicating the outlier was identified a high proportion of the time. Simulations also showed the enormous computational time advantage of the EIF. Diagnostics applied to body mass index in nuclear families detected observations influential on the lod score and model parameter estimates. Conclusions The EIF is a practical diagnostic tool that has the advantages of high sensitivity and quick computation. PMID:19172086

GaAs-based resonant tunneling diode (RTD) epitaxy on Si for highly sensitive strain gauge applications.

PubMed

Li, Jie; Guo, Hao; Liu, Jun; Tang, Jun; Ni, Haiqiao; Shi, Yunbo; Xue, Chenyang; Niu, Zhichuan; Zhang, Wendong; Li, Mifeng; Yu, Ying

2013-05-08

As a highly sensitive strain gauge element, GaAs-based resonant tunneling diode (RTD) has already been applied in microelectromechanical system (MEMS) sensors. Due to poor mechanical properties and high cost, GaAs-based material has been limited in applications as the substrate for MEMS. In this work, we present a method to fabricate the GaAs-based RTD on Si substrate. From the experimental results, it can be concluded that the piezoresistive coefficient achieved with this method reached 3.42 × 10-9 m2/N, which is about an order of magnitude higher than the Si-based semiconductor piezoresistors.

Improving the sensitivity and accuracy of gamma activation analysis for the rapid determination of gold in mineral ores.

PubMed

Tickner, James; Ganly, Brianna; Lovric, Bojan; O'Dwyer, Joel

2017-04-01

Mining companies rely on chemical analysis methods to determine concentrations of gold in mineral ore samples. As gold is often mined commercially at concentrations around 1 part-per-million, it is necessary for any analysis method to provide good sensitivity as well as high absolute accuracy. We describe work to improve both the sensitivity and accuracy of the gamma activation analysis (GAA) method for gold. We present analysis results for several suites of ore samples and discuss the design of a GAA facility designed to replace conventional chemical assay in industrial applications. Copyright © 2017. Published by Elsevier Ltd.

Development of a generalized perturbation theory method for sensitivity analysis using continuous-energy Monte Carlo methods

DOE PAGES

Perfetti, Christopher M.; Rearden, Bradley T.

2016-03-01

The sensitivity and uncertainty analysis tools of the ORNL SCALE nuclear modeling and simulation code system that have been developed over the last decade have proven indispensable for numerous application and design studies for nuclear criticality safety and reactor physics. SCALE contains tools for analyzing the uncertainty in the eigenvalue of critical systems, but cannot quantify uncertainty in important neutronic parameters such as multigroup cross sections, fuel fission rates, activation rates, and neutron fluence rates with realistic three-dimensional Monte Carlo simulations. A more complete understanding of the sources of uncertainty in these design-limiting parameters could lead to improvements in processmore » optimization, reactor safety, and help inform regulators when setting operational safety margins. A novel approach for calculating eigenvalue sensitivity coefficients, known as the CLUTCH method, was recently explored as academic research and has been found to accurately and rapidly calculate sensitivity coefficients in criticality safety applications. The work presented here describes a new method, known as the GEAR-MC method, which extends the CLUTCH theory for calculating eigenvalue sensitivity coefficients to enable sensitivity coefficient calculations and uncertainty analysis for a generalized set of neutronic responses using high-fidelity continuous-energy Monte Carlo calculations. Here, several criticality safety systems were examined to demonstrate proof of principle for the GEAR-MC method, and GEAR-MC was seen to produce response sensitivity coefficients that agreed well with reference direct perturbation sensitivity coefficients.« less

Comparison of two preparatory techniques for urine cytology.

PubMed Central

Dhundee, J; Rigby, H S

1990-01-01

Two methods of preparation of urine for cytology were compared retrospectively. In method 1 cells in the urine were fixed after the preparation of the smear; in method 2 the cells were fixed before smear preparation. Urine cytology reports were correlated with subsequent histological analysis. The specificities of urine cytology using both methods were high (99%). The sensitivity using method 1 was 87%; using method 2 it was 65%. This difference was significant. The cell preparation technique therefore significantly changes the sensitivity of urine cytology. Cellular fixation after smear preparation is preferable to smear preparation after fixation. PMID:2266176

Fluorescent microplate assay method for high-throughput detection of lipase transesterification activity.

PubMed

Zheng, Jianyong; Wei, Wei; Lan, Xing; Zhang, Yinjun; Wang, Zhao

2018-05-15

This study describes a sensitive and fluorescent microplate assay method to detect lipase transesterification activity. Lipase-catalyzed transesterification between butyryl 4-methyl umbelliferone (Bu-4-Mu) and methanol in tert-butanol was selected as the model reaction. The release of 4-methylumbelliferone (4-Mu) in the reaction was determined by detecting the fluorescence intensity at λ ex 330 nm and λ em 390 nm. Several lipases were used to investigate the accuracy and efficiency of the proposed method. Apparent Michaelis constant (Km) was calculated for transesterification between Bu-4-Mu and methanol by the lipases. The main advantages of the assay method include high sensitivity, inexpensive reagents, and simple detection process. Copyright © 2018 Elsevier Inc. All rights reserved.

Simultaneous multi-headed imager geometry calibration method

DOEpatents

Tran, Vi-Hoa [Newport News, VA; Meikle, Steven Richard [Penshurst, AU; Smith, Mark Frederick [Yorktown, VA

2008-02-19

A method for calibrating multi-headed high sensitivity and high spatial resolution dynamic imaging systems, especially those useful in the acquisition of tomographic images of small animals. The method of the present invention comprises: simultaneously calibrating two or more detectors to the same coordinate system; and functionally correcting for unwanted detector movement due to gantry flexing.

Fluorescent Nanomaterials for the Development of Latent Fingerprints in Forensic Sciences

PubMed Central

Li, Ming; Yu, Aoyang; Zhu, Ye

2018-01-01

This review presents an overview on the application of latent fingerprint development techniques in forensic sciences. At present, traditional developing methods such as powder dusting, cyanoacrylate fuming, chemical method, and small particle reagent method, have all been gradually compromised given their emerging drawbacks such as low contrast, sensitivity, and selectivity, as well as high toxicity. Recently, much attention has been paid to the use of fluorescent nanomaterials including quantum dots (QDs) and rare earth upconversion fluorescent nanomaterials (UCNMs) due to their unique optical and chemical properties. Thus, this review lays emphasis on latent fingerprint development based on QDs and UCNMs. Compared to latent fingerprint development by traditional methods, the new methods using fluorescent nanomaterials can achieve high contrast, sensitivity, and selectivity while showing reduced toxicity. Overall, this review provides a systematic overview on such methods. PMID:29657570

Ultra-sensitive, stable isotope assisted quantification of multiple urinary mycotoxin exposure biomarkers.

PubMed

Šarkanj, Bojan; Ezekiel, Chibundu N; Turner, Paul C; Abia, Wilfred A; Rychlik, Michael; Krska, Rudolf; Sulyok, Michael; Warth, Benedikt

2018-08-17

There is a critical need to better understand the patterns, levels and combinatory effects of exposures we are facing through our diet and environment. Mycotoxin mixtures are of particular concern due to chronic low dose exposures caused by naturally contaminated food. To facilitate new insights into their role in chronic disease, mycotoxins and their metabolites are quantified in bio-fluids as biomarkers of exposure. Here, we describe a highly sensitive urinary assay based on ultra-high performance liquid chromatography - tandem mass spectrometer (UHPLC-MS/MS) and 13 C-labelled or deuterated internal standards covering the most relevant regulated and emerging mycotoxins. Utilizing enzymatic pre-treatment, solid phase extraction and UHPLC separation, the sensitivity of the method was significantly higher (10-160x lower LODs) than in a previously described method used for comparison purpose, and stable isotopes provided compensation for challenging matrix effects. This method was in-house validated and applied to re-assess mycotoxin exposure in urine samples obtained from Nigerian children, adolescent and adults, naturally exposed through their regular diet. Owing to the methods high sensitivity, biomarkers were detected in all samples. The mycoestrogen zearalenone was the most frequently detected contaminant (82%) but also ochratoxin A (76%), aflatoxin M 1 (73%) and fumonisin B 1 (71%) were quantified in a large share of urines. Overall, 57% of 120 urines were contaminated with both, aflatoxin M 1 and fumonisin B 1 , and other co-exposures were frequent. These results clearly demonstrate the advanced performance of the method to assess lowest background exposures (pg mL -1 range) using a single, highly robust assay that will allow for the systematic investigation of low dose effects on human health. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

A New Pulse Pileup Rejection Method Based on Position Shift Identification

NASA Astrophysics Data System (ADS)

Gu, Z.; Prout, D. L.; Taschereau, R.; Bai, B.; Chatziioannou, A. F.

2016-02-01

Pulse pileup events degrade the signal-to-noise ratio (SNR) of nuclear medicine data. When such events occur in multiplexed detectors, they cause spatial misposition, energy spectrum distortion and degraded timing resolution, which leads to image artifacts. Pulse pileup is pronounced in PETbox4, a bench top PET scanner dedicated to high sensitivity and high resolution imaging of mice. In that system, the combination of high absolute sensitivity, long scintillator decay time (BGO) and highly multiplexed electronics lead to a significant fraction of pulse pileup, reached at lower total activity than for comparable instruments. In this manuscript, a new pulse pileup rejection method named position shift rejection (PSR) is introduced. The performance of PSR is compared with a conventional leading edge rejection (LER) method and with no pileup rejection implemented (NoPR). A comprehensive digital pulse library was developed for objective evaluation and optimization of the PSR and LER, in which pulse waveforms were directly recorded from real measurements exactly representing the signals to be processed. Physical measurements including singles event acquisition, peak system sensitivity and NEMA NU-4 image quality phantom were also performed in the PETbox4 system to validate and compare the different pulse pile-up rejection methods. The evaluation of both physical measurements and model pulse trains demonstrated that the new PSR performs more accurate pileup event identification and avoids erroneous rejection of valid events. For the PETbox4 system, this improvement leads to a significant recovery of sensitivity at low count rates, amounting to about 1/4th of the expected true coincidence events, compared to the LER method. Furthermore, with the implementation of PSR, optimal image quality can be achieved near the peak noise equivalent count rate (NECR).

A sensitive and specific LC-MS/MS method for rapid diagnosis of Niemann-Pick C1 disease from human plasma[S

PubMed Central

Jiang, Xuntian; Sidhu, Rohini; Porter, Forbes D.; Yanjanin, Nicole M.; Speak, Anneliese O.; te Vruchte, Danielle Taylor; Platt, Frances M.; Fujiwara, Hideji; Scherrer, David E.; Zhang, Jessie; Dietzen, Dennis J.; Schaffer, Jean E.; Ory, Daniel S.

2011-01-01

Niemann-Pick type C1 (NPC1) disease is a rare, progressively fatal neurodegenerative disease for which there are no FDA-approved therapies. A major barrier to developing new therapies for this disorder has been the lack of a sensitive and noninvasive diagnostic test. Recently, we demonstrated that two cholesterol oxidation products, specifically cholestane-3β,5α,6β-triol (3β,5α,6β-triol) and 7-ketocholesterol (7-KC), were markedly increased in the plasma of human NPC1 subjects, suggesting a role for these oxysterols in diagnosis of NPC1 disease and evaluation of therapeutics in clinical trials. In the present study, we describe the development of a sensitive and specific LC-MS/MS method for quantifying 3β,5α,6β-triol and 7-KC human plasma after derivatization with N,N-dimethylglycine. We show that dimethylglycine derivatization successfully enhanced the ionization and fragmentation of 3β,5α,6β-triol and 7-KC for mass spectrometric detection of the oxysterol species in human plasma. The oxysterol dimethylglycinates were resolved with high sensitivity and selectivity, and enabled accurate quantification of 3β,5α,6β-triol and 7-KC concentrations in human plasma. The LC-MS/MS assay was able to discriminate with high sensitivity and specificity between control and NPC1 subjects, and offers for the first time a noninvasive, rapid, and highly sensitive method for diagnosis of NPC1 disease. PMID:21518695

An investigation of a PRESAGE® in-vivo dosimeter for brachytherapy

PubMed Central

Vidovic, A K; Juang, T; Meltsner, S; Adamovics, J; Chino, J; Steffey, B; Craciunescu, O; Oldham, M

2014-01-01

Determining accurate in-vivo dosimetry in brachytherapy treatment with high dose gradients is challenging. Here we introduce, investigate, and characterize a novel in-vivo dosimeter and readout technique with the potential to address this problem. A cylindrical (4 mm x 20 mm) tissue equivalent radiochromic dosimeter PRESAGE® In-Vivo (PRESAGE®-IV) is investigated. Two readout methods of the radiation induced change in optical density (OD) were investigated: (i) volume-averaged readout by spectrophotometer, and (ii) a line profile readout by 2D projection imaging utilizing a high-resolution (50 micron) telecentric optical system. Method (i) is considered the gold standard when applied to PRESAGE® in optical cuvettes. The feasibility of both methods was evaluated by comparison to standard measurements on PRESAGE® in optical cuvettes via spectrophotometer. An end-to-end feasibility study was performed by a side-by-side comparison with TLDs in an 192Ir HDR delivery. 7 and 8 Gy was delivered to PRESAGE®-IV and TLDs attached to the surface of a vaginal cylinder. Known geometry enabled direct comparison of measured dose with commissioned treatment planning system. A high-resolution readout study under a steep dose gradient region showed 98.9% (5%/1 mm) agreement between PRESAGE®-IV and Gafchromic® EBT2 Film. Spectrometer measurements exhibited a linear dose response between 0–15 Gy with sensitivity of 0.0133 ± 0.0007 ΔOD/(Gy·cm) at the 95% confidence interval. Method (ii) yielded a linear response with sensitivity of 0.0132 ± 0.0006 (ΔOD/Gy), within 2% of method (i). Method (i) has poor spatial resolution due to volume averaging. Method (ii) has higher resolution (~1mm) without loss of sensitivity or increased noise. Both readout methods are shown to be feasible. The end-to-end comparison revealed a 2.5% agreement between PRESAGE®-IV and treatment plan in regions of uniform high dose. PRESAGE®-IV shows promise for in-vivo dose verification, although improved sensitivity would be desirable. Advantages include high-resolution, convenience and fast, low-cost readout. PMID:24957850

An investigation of a PRESAGE® in vivo dosimeter for brachytherapy

NASA Astrophysics Data System (ADS)

Vidovic, A. K.; Juang, T.; Meltsner, S.; Adamovics, J.; Chino, J.; Steffey, B.; Craciunescu, O.; Oldham, M.

2014-07-01

Determining accurate in vivo dosimetry in brachytherapy treatment with high dose gradients is challenging. Here we introduce, investigate, and characterize a novel in vivo dosimeter and readout technique with the potential to address this problem. A cylindrical (4 mm × 20 mm) tissue equivalent radiochromic dosimeter PRESAGE® in vivo (PRESAGE®-IV) is investigated. Two readout methods of the radiation induced change in optical density (OD) were investigated: (i) volume-averaged readout by spectrophotometer, and (ii) a line profile readout by 2D projection imaging utilizing a high-resolution (50 micron) telecentric optical system. Method (i) is considered the gold standard when applied to PRESAGE® in optical cuvettes. The feasibility of both methods was evaluated by comparison to standard measurements on PRESAGE® in optical cuvettes via spectrophotometer. An end-to-end feasibility study was performed by a side-by-side comparison with TLDs in an 192Ir HDR delivery. 7 and 8 Gy was delivered to PRESAGE®-IV and TLDs attached to the surface of a vaginal cylinder. Known geometry enabled direct comparison of measured dose with a commissioned treatment planning system. A high-resolution readout study under a steep dose gradient region showed 98.9% (5%/1 mm) agreement between PRESAGE®-IV and Gafchromic® EBT2 Film. Spectrometer measurements exhibited a linear dose response between 0-15 Gy with sensitivity of 0.0133 ± 0.0007 ΔOD/(Gy ṡ cm) at the 95% confidence interval. Method (ii) yielded a linear response with sensitivity of 0.0132 ± 0.0006 (ΔOD/Gy), within 2% of method (i). Method (i) has poor spatial resolution due to volume averaging. Method (ii) has higher resolution (˜1 mm) without loss of sensitivity or increased noise. Both readout methods are shown to be feasible. The end-to-end comparison revealed a 2.5% agreement between PRESAGE®-IV and treatment plan in regions of uniform high dose. PRESAGE®-IV shows promise for in vivo dose verification, although improved sensitivity would be desirable. Advantages include high-resolution, convenience and fast, low-cost readout.

Sagnac interferometry with coherent vortex superposition states in exciton-polariton condensates

NASA Astrophysics Data System (ADS)

Moxley, Frederick Ira; Dowling, Jonathan P.; Dai, Weizhong; Byrnes, Tim

2016-05-01

We investigate prospects of using counter-rotating vortex superposition states in nonequilibrium exciton-polariton Bose-Einstein condensates for the purposes of Sagnac interferometry. We first investigate the stability of vortex-antivortex superposition states, and show that they survive at steady state in a variety of configurations. Counter-rotating vortex superpositions are of potential interest to gyroscope and seismometer applications for detecting rotations. Methods of improving the sensitivity are investigated by targeting high momentum states via metastable condensation, and the application of periodic lattices. The sensitivity of the polariton gyroscope is compared to its optical and atomic counterparts. Due to the large interferometer areas in optical systems and small de Broglie wavelengths for atomic BECs, the sensitivity per detected photon is found to be considerably less for the polariton gyroscope than with competing methods. However, polariton gyroscopes have an advantage over atomic BECs in a high signal-to-noise ratio, and have other practical advantages such as room-temperature operation, area independence, and robust design. We estimate that the final sensitivities including signal-to-noise aspects are competitive with existing methods.

Graphene oxide-coated stir bar sorptive extraction of trace aflatoxins from soy milk followed by high performance liquid chromatography-laser-induced fluorescence detection.

PubMed

Ma, Haiyan; Ran, Congcong; Li, Mengjiao; Gao, Jinglin; Wang, Xinyu; Zhang, Lina; Bian, Jing; Li, Junmei; Jiang, Ye

2018-04-01

Mycotoxins are potential food pollutants produced by fungi. Among them, aflatoxins (AFs) are the most toxic. Therefore, AFs were selected as models, and a sensitive, simple and green graphene oxide (GO)-based stir bar sorptive extraction (SBSE) method was developed for extraction and determination of AFs with high performance liquid chromatography-laser-induced fluorescence detector (HPLC-LIF). This method improved the sensitivity of AFs detection and solved the deposition difficulty of the direct use of GO as adsorbent. Several parameters including a spiked amount of NaCl, stirring rate, extraction time and desorption time were investigated. Under optimal conditions, the quantitative method had low limits of detection of 2.4-8.0 pg/mL, which were better than some reported AFs analytical methods. The developed method has been applied to soy milk samples with good recoveries ranging from 80.5 to 102.3%. The prepared GO-based SBSE can be used as a sensitive screening technique for detecting AFs in soy milk.

A branch-migration based fluorescent probe for straightforward, sensitive and specific discrimination of DNA mutations

PubMed Central

Xiao, Xianjin; Wu, Tongbo; Xu, Lei; Chen, Wei

2017-01-01

Abstract Genetic mutations are important biomarkers for cancer diagnostics and surveillance. Preferably, the methods for mutation detection should be straightforward, highly specific and sensitive to low-level mutations within various sequence contexts, fast and applicable at room-temperature. Though some of the currently available methods have shown very encouraging results, their discrimination efficiency is still very low. Herein, we demonstrate a branch-migration based fluorescent probe (BM probe) which is able to identify the presence of known or unknown single-base variations at abundances down to 0.3%-1% within 5 min, even in highly GC-rich sequence regions. The discrimination factors between the perfect-match target and single-base mismatched target are determined to be 89–311 by measurement of their respective branch-migration products via polymerase elongation reactions. The BM probe not only enabled sensitive detection of two types of EGFR-associated point mutations located in GC-rich regions, but also successfully identified the BRAF V600E mutation in the serum from a thyroid cancer patient which could not be detected by the conventional sequencing method. The new method would be an ideal choice for high-throughput in vitro diagnostics and precise clinical treatment. PMID:28201758

Determination of aristolochic acids by high-performance liquid chromatography with fluorescence detection.

PubMed

Wang, Yinan; Chan, Wan

2014-06-25

Nephrotoxic and carcinogenic aristolochic acids (AAs) are naturally occurring nitrophenanthrene carboxylic acids in the herbal genus Aristolochia. The misuse of AA-containing herbs in preparing slimming drugs has caused hundred of cases of kidney disease in Belgium women in a slimming regime in the early 1990s. Accumulating evidence also suggested that prolong dietary intake of AA-contaminated food is one of the major causes to the Balkan endemic nephropathy that was first observed in the late 1950s. Therefore, analytical methods of high sensitivity are extremely important for safeguarding human exposure to AA-containing herbal medicines, herbal remedies, and food composites. In this paper, we describe the development of a new high-performance liquid chromatography coupled fluorescence detector (HPLC-FLD) method for the sensitive determination of AAs. The method makes use of a novel cysteine-induced denitration reaction that "turns on" the fluorescence of AAs for fluorometric detections. Our results showed that the combination of cysteine-induced denitration and HPLC-FLD analysis allows for sensitive quantification of AA-I and AA-II at detection limits of 27.1 and 25.4 ng/g, respectively. The method was validated and has been successfully applied in quantifying AAs in Chinese herbal medicines.

Multi-Component Profiling of Trace Volatiles in Blood by Gas Chromatography/Mass Spectrometry with Dynamic Headspace Extraction

PubMed Central

Kakuta, Shoji; Yamashita, Toshiyuki; Nishiumi, Shin; Yoshida, Masaru; Fukusaki, Eiichiro; Bamba, Takeshi

2015-01-01

A dynamic headspace extraction method (DHS) with high-pressure injection is described. This dynamic extraction method has superior sensitivity to solid phase micro extraction, SPME and is capable of extracting the entire gas phase by purging the headspace of a vial. Optimization of the DHS parameters resulted in a highly sensitive volatile profiling system with the ability to detect various volatile components including alcohols at nanogram levels. The average LOD for a standard volatile mixture was 0.50 ng mL−1, and the average LOD for alcohols was 0.66 ng mL−1. This method was used for the analysis of volatile components from biological samples and compared with acute and chronic inflammation models. The method permitted the identification of volatiles with the same profile pattern as in vitro oxidized lipid-derived volatiles. In addition, the concentration of alcohols and aldehydes from the acute inflammation model samples were significantly higher than that for the chronic inflammation model samples. The different profiles between these samples could also be identified by this method. Finally, it was possible to analyze alcohols and low-molecular-weight volatiles that are difficult to analyze by SPME in high sensitivity and to show volatile profiling based on multi-volatile simultaneous analysis. PMID:26819905

Multi-Component Profiling of Trace Volatiles in Blood by Gas Chromatography/Mass Spectrometry with Dynamic Headspace Extraction.

PubMed

Kakuta, Shoji; Yamashita, Toshiyuki; Nishiumi, Shin; Yoshida, Masaru; Fukusaki, Eiichiro; Bamba, Takeshi

2015-01-01

A dynamic headspace extraction method (DHS) with high-pressure injection is described. This dynamic extraction method has superior sensitivity to solid phase micro extraction, SPME and is capable of extracting the entire gas phase by purging the headspace of a vial. Optimization of the DHS parameters resulted in a highly sensitive volatile profiling system with the ability to detect various volatile components including alcohols at nanogram levels. The average LOD for a standard volatile mixture was 0.50 ng mL(-1), and the average LOD for alcohols was 0.66 ng mL(-1). This method was used for the analysis of volatile components from biological samples and compared with acute and chronic inflammation models. The method permitted the identification of volatiles with the same profile pattern as in vitro oxidized lipid-derived volatiles. In addition, the concentration of alcohols and aldehydes from the acute inflammation model samples were significantly higher than that for the chronic inflammation model samples. The different profiles between these samples could also be identified by this method. Finally, it was possible to analyze alcohols and low-molecular-weight volatiles that are difficult to analyze by SPME in high sensitivity and to show volatile profiling based on multi-volatile simultaneous analysis.

Highly sensitive detection of caspase-3 activities via a nonconjugated gold nanoparticle-quantum dot pair mediated by an inner-filter effect.

PubMed

Li, Jingwen; Li, Xinming; Shi, Xiujuan; He, Xuewen; Wei, Wei; Ma, Nan; Chen, Hong

2013-10-09

We describe here a simple fluorometric assay for the highly sensitive detection of caspase-3 activities on the basis of the inner-filter effect of gold nanoparticles (AuNPs) on CdTe quantum dots (QDs). The method takes advantage of the high molar absorptivity of the plasmon band of gold nanoparticles as well as the large absorption band shift from 520 to 680 nm upon nanoparticle aggregation. When labeled with a peptide possessing the caspase-3 cleavage sequence (DEVD), the monodispersed Au-Ps (peptide-modified AuNPs) exhibited a tendency to aggregate when exposed to caspase-3, which induced the absorption band transition from 520 to 680 nm and turned on the fluorescence of the CdTe QDs for caspase-3 sensing. Under optimum conditions, a high sensitivity towards caspase-3 was achieved with a detection limit as low as 18 pM, which was much lower than the corresponding assays based on absorbance or other approaches. Overall, we demonstrated a facile and sensitive approach for caspase-3 detection, and we expected that this method could be potentially generalized to design more fluorescent assays for sensing other bioactive entities.

A rapid, ratiometric, enzyme-free, and sensitive single-step miRNA detection using three-way junction based FRET probes

NASA Astrophysics Data System (ADS)

Luo, Qingying; Liu, Lin; Yang, Cai; Yuan, Jing; Feng, Hongtao; Chen, Yan; Zhao, Peng; Yu, Zhiqiang; Jin, Zongwen

2018-03-01

MicroRNAs (miRNAs) are single stranded endogenous molecules composed of only 18-24 nucleotides which are critical for gene expression regulating the translation of messenger RNAs. Conventional methods based on enzyme-assisted nucleic acid amplification techniques have many problems, such as easy contamination, high cost, susceptibility to false amplification, and tendency to have sequence mismatches. Here we report a rapid, ratiometric, enzyme-free, sensitive, and highly selective single-step miRNA detection using three-way junction assembled (or self-assembled) FRET probes. The developed strategy can be operated within the linear range from subnanomolar to hundred nanomolar concentrations of miRNAs. In comparison with the traditional approaches, our method showed high sensitivity for the miRNA detection and extreme selectivity for the efficient discrimination of single-base mismatches. The results reveal that the strategy paved a new avenue for the design of novel highly specific probes applicable in diagnostics and potentially in microscopic imaging of miRNAs in real biological environments.

Method-independent, Computationally Frugal Convergence Testing for Sensitivity Analysis Techniques

NASA Astrophysics Data System (ADS)

Mai, J.; Tolson, B.

2017-12-01

The increasing complexity and runtime of environmental models lead to the current situation that the calibration of all model parameters or the estimation of all of their uncertainty is often computationally infeasible. Hence, techniques to determine the sensitivity of model parameters are used to identify most important parameters. All subsequent model calibrations or uncertainty estimation procedures focus then only on these subsets of parameters and are hence less computational demanding. While the examination of the convergence of calibration and uncertainty methods is state-of-the-art, the convergence of the sensitivity methods is usually not checked. If any, bootstrapping of the sensitivity results is used to determine the reliability of the estimated indexes. Bootstrapping, however, might as well become computationally expensive in case of large model outputs and a high number of bootstraps. We, therefore, present a Model Variable Augmentation (MVA) approach to check the convergence of sensitivity indexes without performing any additional model run. This technique is method- and model-independent. It can be applied either during the sensitivity analysis (SA) or afterwards. The latter case enables the checking of already processed sensitivity indexes. To demonstrate the method's independency of the convergence testing method, we applied it to two widely used, global SA methods: the screening method known as Morris method or Elementary Effects (Morris 1991) and the variance-based Sobol' method (Solbol' 1993). The new convergence testing method is first scrutinized using 12 analytical benchmark functions (Cuntz & Mai et al. 2015) where the true indexes of aforementioned three methods are known. This proof of principle shows that the method reliably determines the uncertainty of the SA results when different budgets are used for the SA. The results show that the new frugal method is able to test the convergence and therefore the reliability of SA results in an efficient way. The appealing feature of this new technique is the necessity of no further model evaluation and therefore enables checking of already processed sensitivity results. This is one step towards reliable and transferable, published sensitivity results.

The predictive value of magnetic resonance imaging of retinoblastoma for the likelihood of high-risk pathologic features.

PubMed

Hiasat, Jamila G; Saleh, Alaa; Al-Hussaini, Maysa; Al Nawaiseh, Ibrahim; Mehyar, Mustafa; Qandeel, Monther; Mohammad, Mona; Deebajah, Rasha; Sultan, Iyad; Jaradat, Imad; Mansour, Asem; Yousef, Yacoub A

2018-06-01

To evaluate the predictive value of magnetic resonance imaging in retinoblastoma for the likelihood of high-risk pathologic features. A retrospective study of 64 eyes enucleated from 60 retinoblastoma patients. Contrast-enhanced magnetic resonance imaging was performed before enucleation. Main outcome measures included demographics, laterality, accuracy, sensitivity, and specificity of magnetic resonance imaging in detecting high-risk pathologic features. Optic nerve invasion and choroidal invasion were seen microscopically in 34 (53%) and 28 (44%) eyes, respectively, while they were detected in magnetic resonance imaging in 22 (34%) and 15 (23%) eyes, respectively. The accuracy of magnetic resonance imaging in detecting prelaminar invasion was 77% (sensitivity 89%, specificity 98%), 56% for laminar invasion (sensitivity 27%, specificity 94%), 84% for postlaminar invasion (sensitivity 42%, specificity 98%), and 100% for optic cut edge invasion (sensitivity100%, specificity 100%). The accuracy of magnetic resonance imaging in detecting focal choroidal invasion was 48% (sensitivity 33%, specificity 97%), and 84% for massive choroidal invasion (sensitivity 53%, specificity 98%), and the accuracy in detecting extrascleral extension was 96% (sensitivity 67%, specificity 98%). Magnetic resonance imaging should not be the only method to stratify patients at high risk from those who are not, eventhough it can predict with high accuracy extensive postlaminar optic nerve invasion, massive choroidal invasion, and extrascleral tumor extension.

Mass spectrometric-based stable isotopic 2-aminobenzoic acid glycan mapping for rapid glycan screening of biotherapeutics.

PubMed

Prien, Justin M; Prater, Bradley D; Qin, Qiang; Cockrill, Steven L

2010-02-15

Fast, sensitive, robust methods for "high-level" glycan screening are necessary during various stages of a biotherapeutic product's lifecycle, including clone selection, process changes, and quality control for lot release testing. Traditional glycan screening involves chromatographic or electrophoretic separation-based methods, and, although reproducible, these methods can be time-consuming. Even ultrahigh-performance chromatographic and microfluidic integrated LC/MS systems, which work on the tens of minute time scale, become lengthy when hundreds of samples are to be analyzed. Comparatively, a direct infusion mass spectrometry (MS)-based glycan screening method acquires data on a millisecond time scale, exhibits exquisite sensitivity and reproducibility, and is amenable to automated peak annotation. In addition, characterization of glycan species via sequential mass spectrometry can be performed simultaneously. Here, we demonstrate a quantitative high-throughput MS-based mapping approach using stable isotope 2-aminobenzoic acid (2-AA) for rapid "high-level" glycan screening.

A simple method to measure critical angles for high-sensitivity differential refractometry.

PubMed

Zilio, S C

2012-01-16

A total internal reflection-based differencial refractometer, capable of measuring the real and imaginary parts of the complex refractive index in real time, is presented. The device takes advantage of the phase difference acquired by s- and p-polarized light to generate an easily detectable minimum at the reflected profile. The method allows to sensitively measuring transparent and turbid liquid samples.

Comparison of lifetime-based methods for 2D phosphor thermometry in high-temperature environment

NASA Astrophysics Data System (ADS)

Peng, Di; Liu, Yingzheng; Zhao, Xiaofeng; Kim, Kyung Chun

2016-09-01

This paper discusses the currently available techniques for 2D phosphor thermometry, and compares the performance of two lifetime-based methods: high-speed imaging and the dual-gate. High-speed imaging resolves luminescent decay with a fast frame rate, and has become a popular method for phosphor thermometry in recent years. But it has disadvantages such as high equipment cost and long data processing time, and it would fail at sufficiently high temperature due to a low signal-to-noise ratio and short lifetime. The dual-gate method only requires two images on the decay curve and therefore greatly reduces cost in hardware and processing time. A dual-gate method for phosphor thermometry has been developed and compared with the high-speed imaging method through both calibration and a jet impingement experiment. Measurement uncertainty has been evaluated for a temperature range of 473-833 K. The effects of several key factors on uncertainty have been discussed, including the luminescent signal level, the decay lifetime and temperature sensitivity. The results show that both methods are valid for 2D temperature sensing within the given range. The high-speed imaging method shows less uncertainty at low temperatures where the signal level and the lifetime are both sufficient, but its performance is degraded at higher temperatures due to a rapidly reduced signal and lifetime. For T  >  750 K, the dual-gate method outperforms the high-speed imaging method thanks to its superiority in signal-to-noise ratio and temperature sensitivity. The dual-gate method has great potential for applications in high-temperature environments where the high-speed imaging method is not applicable.

Engineering 'cell robots' for parallel and highly sensitive screening of biomolecules under in vivo conditions.

PubMed

Song, Lifu; Zeng, An-Ping

2017-11-09

Cells are capable of rapid replication and performing tasks adaptively and ultra-sensitively and can be considered as cheap "biological-robots". Here we propose to engineer cells for screening biomolecules in parallel and with high sensitivity. Specifically, we place the biomolecule variants (library) on the bacterial phage M13. We then design cells to screen the library based on cell-phage interactions mediated by a specific intracellular signal change caused by the biomolecule of interest. For proof of concept, we used intracellular lysine concentration in E. coli as a signal to successfully screen variants of functional aspartate kinase III (AK-III) under in vivo conditions, a key enzyme in L-lysine biosynthesis which is strictly inhibited by L-lysine. Comparative studies with flow cytometry method failed to distinguish the wild-type from lysine resistance variants of AK-III, confirming a higher sensitivity of the method. It opens up a new and effective way of in vivo high-throughput screening for functional molecules and can be easily implemented at low costs.

Highly sensitive image-derived indices of water-stressed plants using hyperspectral imaging in SWIR and histogram analysis

PubMed Central

Kim, David M.; Zhang, Hairong; Zhou, Haiying; Du, Tommy; Wu, Qian; Mockler, Todd C.; Berezin, Mikhail Y.

2015-01-01

The optical signature of leaves is an important monitoring and predictive parameter for a variety of biotic and abiotic stresses, including drought. Such signatures derived from spectroscopic measurements provide vegetation indices – a quantitative method for assessing plant health. However, the commonly used metrics suffer from low sensitivity. Relatively small changes in water content in moderately stressed plants demand high-contrast imaging to distinguish affected plants. We present a new approach in deriving sensitive indices using hyperspectral imaging in a short-wave infrared range from 800 nm to 1600 nm. Our method, based on high spectral resolution (1.56 nm) instrumentation and image processing algorithms (quantitative histogram analysis), enables us to distinguish a moderate water stress equivalent of 20% relative water content (RWC). The identified image-derived indices 15XX nm/14XX nm (i.e. 1529 nm/1416 nm) were superior to common vegetation indices, such as WBI, MSI, and NDWI, with significantly better sensitivity, enabling early diagnostics of plant health. PMID:26531782

New Spectrofluorimetric Method with Enhanced Sensitivity for Determination of Paroxetine in Dosage Forms and Plasma

PubMed Central

Darwish, Ibrahim A.; Amer, Sawsan M.; Abdine, Heba H.; Al-Rayes, Lama I.

2008-01-01

New simple spectrofluorimetric method with enhanced sensitivity has been developed and validated for the determination of the antidepressant paroxetine (PXT) in its dosage forms and plasma. The method was based on nucleophilic substitution reaction of PXT with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in an alkaline medium (pH 8) to form a highly fluorescent derivative that was measured at 545 nm after excitation at 490 nm. The factors affecting the reaction was carefully studied and optimized. The kinetics of the reaction was investigated, and the reaction mechanism was presented. Under the optimized conditions, linear relationship with good correlation coefficient (0.9993) was found between the fluorescence intensity and PXT concentration in the range of 80–800 ng ml−1. The limits of detection and quantitation for the method were 25 and 77 ng ml−1, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 3%. The proposed method was successfully applied to the determination of PXT in its pharmaceutical tablets with good accuracy; the recovery values were 100.2 ± 1.61%. The results obtained by the proposed method were comparable with those obtained by the official method. The proposed method is superior to the previously reported spectrofluorimetric method for determination of PXT in terms of its higher sensitivity and wider linear range. The high sensitivity of the method allowed its successful application to the analysis of PXT in spiked human plasma. The proposed method is practical and valuable for its routine application in quality control and clinical laboratories for analysis of PXT. PMID:19609398

A fluorescent graphitic carbon nitride nanosheet biosensor for highly sensitive, label-free detection of alkaline phosphatase.

PubMed

Xiang, Mei-Hao; Liu, Jin-Wen; Li, Na; Tang, Hao; Yu, Ru-Qin; Jiang, Jian-Hui

2016-02-28

Graphitic C3N4 (g-C3N4) nanosheets provide an attractive option for bioprobes and bioimaging applications. Utilizing highly fluorescent and water-dispersible ultrathin g-C3N4 nanosheets, a highly sensitive, selective and label-free biosensor has been developed for ALP detection for the first time. The developed approach utilizes a natural substrate of ALP in biological systems and thus affords very high catalytic efficiency. This novel biosensor is demonstrated to enable quantitative analysis of ALP in a wide range from 0.1 to 1000 U L(-1) with a low detection limit of 0.08 U L(-1), which is among the most sensitive assays for ALP. It is expected that the developed method may provide a low-cost, convenient, rapid and highly sensitive platform for ALP-based clinical diagnostics and biomedical applications.

Headspace-SPME-GC/MS as a simple cleanup tool for sensitive 2,6-diisopropylphenol analysis from lipid emulsions and adaptable to other matrices.

PubMed

Pickl, Karin E; Adamek, Viktor; Gorges, Roland; Sinner, Frank M

2011-07-15

Due to increased regulatory requirements, the interaction of active pharmaceutical ingredients with various surfaces and solutions during production and storage is gaining interest in the pharmaceutical research field, in particular with respect to development of new formulations, new packaging material and the evaluation of cleaning processes. Experimental adsorption/absorption studies as well as the study of cleaning processes require sophisticated analytical methods with high sensitivity for the drug of interest. In the case of 2,6-diisopropylphenol - a small lipophilic drug which is typically formulated as lipid emulsion for intravenous injection - a highly sensitive method in the concentration range of μg/l suitable to be applied to a variety of different sample matrices including lipid emulsions is needed. We hereby present a headspace-solid phase microextraction (HS-SPME) approach as a simple cleanup procedure for sensitive 2,6-diisopropylphenol quantification from diverse matrices choosing a lipid emulsion as the most challenging matrix with regard to complexity. By combining the simple and straight forward HS-SPME sample pretreatment with an optimized GC-MS quantification method a robust and sensitive method for 2,6-diisopropylphenol was developed. This method shows excellent sensitivity in the low μg/l concentration range (5-200μg/l), good accuracy (94.8-98.8%) and precision (intraday-precision 0.1-9.2%, inter-day precision 2.0-7.7%). The method can be easily adapted to other, less complex, matrices such as water or swab extracts. Hence, the presented method holds the potential to serve as a single and simple analytical procedure for 2,6-diisopropylphenol analysis in various types of samples such as required in, e.g. adsorption/absorption studies which typically deal with a variety of different surfaces (steel, plastic, glass, etc.) and solutions/matrices including lipid emulsions. Copyright © 2011 Elsevier B.V. All rights reserved.

Adjoint Sensitivity Analysis for Scale-Resolving Turbulent Flow Solvers

NASA Astrophysics Data System (ADS)

Blonigan, Patrick; Garai, Anirban; Diosady, Laslo; Murman, Scott

2017-11-01

Adjoint-based sensitivity analysis methods are powerful design tools for engineers who use computational fluid dynamics. In recent years, these engineers have started to use scale-resolving simulations like large-eddy simulations (LES) and direct numerical simulations (DNS), which resolve more scales in complex flows with unsteady separation and jets than the widely-used Reynolds-averaged Navier-Stokes (RANS) methods. However, the conventional adjoint method computes large, unusable sensitivities for scale-resolving simulations, which unlike RANS simulations exhibit the chaotic dynamics inherent in turbulent flows. Sensitivity analysis based on least-squares shadowing (LSS) avoids the issues encountered by conventional adjoint methods, but has a high computational cost even for relatively small simulations. The following talk discusses a more computationally efficient formulation of LSS, ``non-intrusive'' LSS, and its application to turbulent flows simulated with a discontinuous-Galkerin spectral-element-method LES/DNS solver. Results are presented for the minimal flow unit, a turbulent channel flow with a limited streamwise and spanwise domain.

New parameters in adaptive testing of ferromagnetic materials utilizing magnetic Barkhausen noise

NASA Astrophysics Data System (ADS)

Pal'a, Jozef; Ušák, Elemír

2016-03-01

A new method of magnetic Barkhausen noise (MBN) measurement and optimization of the measured data processing with respect to non-destructive evaluation of ferromagnetic materials was tested. Using this method we tried to found, if it is possible to enhance sensitivity and stability of measurement results by replacing the traditional MBN parameter (root mean square) with some new parameter. In the tested method, a complex set of the MBN from minor hysteresis loops is measured. Afterward, the MBN data are collected into suitably designed matrices and optimal parameters of MBN with respect to maximum sensitivity to the evaluated variable are searched. The method was verified on plastically deformed steel samples. It was shown that the proposed measuring method and measured data processing bring an improvement of the sensitivity to the evaluated variable when comparing with measuring traditional MBN parameter. Moreover, we found a parameter of MBN, which is highly resistant to the changes of applied field amplitude and at the same time it is noticeably more sensitive to the evaluated variable.

Simple and sensitive method for quantification of fluorescent enzymatic mature and senescent crosslinks of collagen in bone hydrolysate using single-column high performance liquid chromatography.

PubMed

Viguet-Carrin, S; Gineyts, E; Bertholon, C; Delmas, P D

2009-01-01

A rapid high performance liquid chromatographic method was developed including an internal standard for the measurement of mature and senescent crosslinks concentration in non-demineralized bone hydrolysates. To avoid the demineralization which is a tedious step, we developed a method based on the use of a solid-phase extraction procedure to clean-up the samples. It resulted in sensitive and accurate measurements: the detection limits as low as 0.2 pmol for the pyridimium crosslinks and 0.02 pmol for the pentosidine. The inter- and intra-assay coefficients of variation were as low as 5% and 2%, respectively, for all crosslinks.

Loop-mediated isothermal amplification for detection of Staphylococcus aureus in dairy cow suffering from mastitis.

PubMed

Tie, Zhang; Chunguang, Wang; Xiaoyuan, Wei; Xinghua, Zhao; Xiuhui, Zhong

2012-01-01

To develop a rapid detection method of Staphylococcus aureus using loop-mediated isothermal amplification (LAMP), four specific primers were designed according to six distinct sequences of the nuc gene. In addition, the specificity and sensitivity of LAMP were verified and compared with those of PCR. Results showed that the LAMP reaction was completed within 45 min at 62.5°C, and ladder bands were appeared in LAMP products analyzed by gel electrophoresis. After adding 1x SYBR Green l, the positive reaction tube showed green color and the negative reaction tube remained orange, indicating that the LAMP has high specificity. The minimal detectable concentration of LAMP was 1 × 10² CFU/mL and that of PCR was 1 × 10⁴ CFU/mL, indicating that the LAMP was 100 times more sensitive than the PCR. The LAMP method for detection of Staphylococcus aureus has many advantages, such as simple operation, high sensitivity, high specificity, and rapid analysis. Therefore, this method is more suitable for the rapid on-site detection of Staphylococcus aureus.

Facile and scalable disposable sensor based on laser engraved graphene for electrochemical detection of glucose

PubMed Central

Tehrani, Farshad; Bavarian, Behzad

2016-01-01

A novel and highly sensitive disposable glucose sensor strip was developed using direct laser engraved graphene (DLEG) decorated with pulse deposited copper nanocubes (CuNCs). The high reproducibility (96.8%), stability (97.4%) and low cost demonstrated by this 3-step fabrication method indicates that it could be used for high volume manufacturing of disposable glucose strips. The fabrication method also allows for a high degree of flexibility, allowing for control of the electrode size, design, and functionalization method. Additionally, the excellent selectivity and sensitivity (4,532.2 μA/mM.cm2), low detection limit (250 nM), and suitable linear range of 25 μM–4 mM, suggests that these sensors may be a great potential platform for glucose detection within the physiological range for tear, saliva, and/or sweat. PMID:27306706

Facile and scalable disposable sensor based on laser engraved graphene for electrochemical detection of glucose

NASA Astrophysics Data System (ADS)

Tehrani, Farshad; Bavarian, Behzad

2016-06-01

A novel and highly sensitive disposable glucose sensor strip was developed using direct laser engraved graphene (DLEG) decorated with pulse deposited copper nanocubes (CuNCs). The high reproducibility (96.8%), stability (97.4%) and low cost demonstrated by this 3-step fabrication method indicates that it could be used for high volume manufacturing of disposable glucose strips. The fabrication method also allows for a high degree of flexibility, allowing for control of the electrode size, design, and functionalization method. Additionally, the excellent selectivity and sensitivity (4,532.2 μA/mM.cm2), low detection limit (250 nM), and suitable linear range of 25 μM-4 mM, suggests that these sensors may be a great potential platform for glucose detection within the physiological range for tear, saliva, and/or sweat.

A high-sensitivity ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry (UHPLC-HR-TOFMS) method for screening synthetic cannabinoids and other drugs of abuse in urine.

PubMed

Sundström, Mira; Pelander, Anna; Angerer, Verena; Hutter, Melanie; Kneisel, Stefan; Ojanperä, Ilkka

2013-10-01

The continuing emergence of designer drugs imposes high demands on the scope and sensitivity of toxicological drug screening procedures. An ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry (UHPLC-HR-TOFMS) method was developed for screening and simultaneous confirmation of both designer drugs and other drugs of abuse in urine samples in a single run. The method covered selected synthetic cannabinoids and cathinones, amphetamines, natural cannabinoids, opioids, cocaine and other important drugs of abuse, together with their main urinary metabolites. The database consisted of 277 compounds with molecular formula and exact monoisotopic mass; retention time was included for 192 compounds, and primary and secondary qualifier ion exact mass for 191 and 95 compounds, respectively. Following a solid-phase extraction, separation was performed by UHPLC and mass analysis by HR-TOFMS. MS, and broad-band collision-induced dissociation data were acquired at m/z range 50-700. Compound identification was based on a reverse database search with acceptance criteria for retention time, precursor ion mass accuracy, isotopic pattern and abundance of qualifier ions. Mass resolving power in spiked urine samples was on average FWHM 23,500 and mass accuracy 0.3 mDa. The mean and median cut-off concentrations determined for 75 compounds were 4.2 and 1 ng/mL, respectively. The range of cut-off concentrations for synthetic cannabinoids was 0.2-60 ng/mL and for cathinones 0.7-15 ng/mL. The method proved to combine high sensitivity and a wide scope in a manner not previously reported in drugs of abuse screening. The method's feasibility was demonstrated with 50 authentic urine samples.

High sensitivity leak detection method and apparatus

DOEpatents

Myneni, Ganapatic R.

1994-01-01

An improved leak detection method is provided that utilizes the cyclic adsorption and desorption of accumulated helium on a non-porous metallic surface. The method provides reliable leak detection at superfluid helium temperatures. The zero drift that is associated with residual gas analyzers in common leak detectors is virtually eliminated by utilizing a time integration technique. The sensitivity of the apparatus of this disclosure is capable of detecting leaks as small as 1.times.10.sup.-18 atm cc sec.sup.-1.

High sensitivity leak detection method and apparatus

DOEpatents

Myneni, G.R.

1994-09-06

An improved leak detection method is provided that utilizes the cyclic adsorption and desorption of accumulated helium on a non-porous metallic surface. The method provides reliable leak detection at superfluid helium temperatures. The zero drift that is associated with residual gas analyzers in common leak detectors is virtually eliminated by utilizing a time integration technique. The sensitivity of the apparatus of this disclosure is capable of detecting leaks as small as 1 [times] 10[sup [minus]18] atm cc sec[sup [minus]1]. 2 figs.

Probing the SEB Sensitive Depth of a Power MOSFET Using a Two-Photon Absorption Laser Method

NASA Technical Reports Server (NTRS)

Lauenstein, Jean-Marie; Liu, Sandra; Titus, Jeffrey L.; McMorrow, Dale; Casey, Megan C.; Buchner, Stephen P.; Warner, Jeffrey; Phan, Anthony M.; Topper, Alyson D.; Kim, Hak S.;

Performance of the high-sensitivity troponin assay in diagnosing acute myocardial infarction: systematic review and meta-analysis

PubMed Central

Al-Saleh, Ayman; Alazzoni, Ashraf; Al Shalash, Saleh; Ye, Chenglin; Mbuagbaw, Lawrence; Thabane, Lehana; Jolly, Sanjit S.

2014-01-01

Background High-sensitivity cardiac troponin assays have been adopted by many clinical centres worldwide; however, clinicians are uncertain how to interpret the results. We sought to assess the utility of these assays in diagnosing acute myocardial infarction (MI). Methods We carried out a systematic review and meta-analysis of studies comparing high-sensitivity with conventional assays of cardiac troponin levels among adults with suspected acute MI in the emergency department. We searched MEDLINE, EMBASE and Cochrane databases up to April 2013 and used bivariable random-effects modelling to obtain summary parameters for diagnostic accuracy. Results We identified 9 studies that assessed the use of high-sensitivity troponin T assays (n = 9186 patients). The summary sensitivity of these tests in diagnosing acute MI at presentation to the emergency department was estimated to be 0.94 (95% confidence interval [CI] 0.89–0.97); for conventional tests, it was 0.72 (95% CI 0.63–0.79). The summary specificity was 0.73 (95% CI 0.64–0.81) for the high-sensitivity assay compared with 0.95 (95% CI 0.93–0.97) for the conventional assay. The differences in estimates of the summary sensitivity and specificity between the high-sensitivity and conventional assays were statistically significant (p < 0.01). The area under the curve was similar for both tests carried out 3–6 hours after presentation. Three studies assessed the use of high-sensitivity troponin I assays and showed similar results. Interpretation Used at presentation to the emergency department, the high-sensitivity cardiac troponin assay has improved sensitivity, but reduced specificity, compared with the conventional troponin assay. With repeated measurements over 6 hours, the area under the curve is similar for both tests, indicating that the major advantage of the high-sensitivity test is early diagnosis. PMID:25295240

Quantum-dot-sensitized solar cells.

PubMed

Rühle, Sven; Shalom, Menny; Zaban, Arie

2010-08-02

Quantum-dot-sensitized solar cells (QDSCs) are a promising low-cost alternative to existing photovoltaic technologies such as crystalline silicon and thin inorganic films. The absorption spectrum of quantum dots (QDs) can be tailored by controlling their size, and QDs can be produced by low-cost methods. Nanostructures such as mesoporous films, nanorods, nanowires, nanotubes and nanosheets with high microscopic surface area, redox electrolytes and solid-state hole conductors are borrowed from standard dye-sensitized solar cells (DSCs) to fabricate electron conductor/QD monolayer/hole conductor junctions with high optical absorbance. Herein we focus on recent developments in the field of mono- and polydisperse QDSCs. Stability issues are adressed, coating methods are presented, performance is reviewed and special emphasis is given to the importance of energy-level alignment to increase the light to electric power conversion efficiency.

Connectome sensitivity or specificity: which is more important?

PubMed

Zalesky, Andrew; Fornito, Alex; Cocchi, Luca; Gollo, Leonardo L; van den Heuvel, Martijn P; Breakspear, Michael

2016-11-15

Connectomes with high sensitivity and high specificity are unattainable with current axonal fiber reconstruction methods, particularly at the macro-scale afforded by magnetic resonance imaging. Tensor-guided deterministic tractography yields sparse connectomes that are incomplete and contain false negatives (FNs), whereas probabilistic methods steered by crossing-fiber models yield dense connectomes, often with low specificity due to false positives (FPs). Densely reconstructed probabilistic connectomes are typically thresholded to improve specificity at the cost of a reduction in sensitivity. What is the optimal tradeoff between connectome sensitivity and specificity? We show empirically and theoretically that specificity is paramount. Our evaluations of the impact of FPs and FNs on empirical connectomes indicate that specificity is at least twice as important as sensitivity when estimating key properties of brain networks, including topological measures of network clustering, network efficiency and network modularity. Our asymptotic analysis of small-world networks with idealized modular structure reveals that as the number of nodes grows, specificity becomes exactly twice as important as sensitivity to the estimation of the clustering coefficient. For the estimation of network efficiency, the relative importance of specificity grows linearly with the number of nodes. The greater importance of specificity is due to FPs occurring more prevalently between network modules rather than within them. These spurious inter-modular connections have a dramatic impact on network topology. We argue that efforts to maximize the sensitivity of connectome reconstruction should be realigned with the need to map brain networks with high specificity. Copyright © 2016 Elsevier Inc. All rights reserved.

Chinese nurses' perceived barriers and facilitators of ethical sensitivity.

PubMed

Huang, Fei Fei; Yang, Qing; Zhang, Jie; Khoshnood, Kaveh; Zhang, Jing Ping

2016-08-01

An overview of ethical sensitivity among Chinese registered nurses is needed to develop and optimize the education programs and interventions to cultivate and improve ethical sensitivity. The study was conducted to explore the barriers to and facilitators of ethical sensitivity among Chinese registered nurses working in hospital settings. A convergent parallel mixed-methods research design was adopted. In the cross-sectional quantitative study, the Chinese Moral Sensitivity Questionnaire-revised version was used to assess the levels of ethical sensitivity among registered nurses, and the scores were correlated with key demographics, training experiences in ethics, and workplace cultural environments (n = 306). In the qualitative study, semi-structured interviews were used to elicit the nurses' perceptions of the barriers and facilitators in nurturing ethical sensitivity (n = 15). The data were collected from February to June 2014. This study was approved by the Institutional Review Boards of Yale University and Central South University. Despite moderately high overall Chinese Moral Sensitivity Questionnaire-revised version scores, the ethical sensitivity among Chinese nurses lags in practice. Barriers to ethical sensitivity include the lack of knowledge related to ethics, lack of working experience as a nurse, the hierarchical organizational climate, and the conformist working attitude. The positive workplace cultural environments and application of ethical knowledge in practice were considered potential facilitators of ethical sensitivity. The findings of this study were compared with studies from other countries to examine the barriers and facilitators of ethical sensitivity in Chinese nurses. This mixed-methods study showed that even though the Chinese nurses have moderately high sensitivity to the ethical issues encountered in hospitals, there is still room for improvement. The barriers to and facilitators of ethical sensitivity identified here offer new and important strategies to support and enhance the nurses' sensitivity to ethical issues. © The Author(s) 2015.

Improving multi-objective reservoir operation optimization with sensitivity-informed problem decomposition

NASA Astrophysics Data System (ADS)

Chu, J. G.; Zhang, C.; Fu, G. T.; Li, Y.; Zhou, H. C.

2015-04-01

This study investigates the effectiveness of a sensitivity-informed method for multi-objective operation of reservoir systems, which uses global sensitivity analysis as a screening tool to reduce the computational demands. Sobol's method is used to screen insensitive decision variables and guide the formulation of the optimization problems with a significantly reduced number of decision variables. This sensitivity-informed problem decomposition dramatically reduces the computational demands required for attaining high quality approximations of optimal tradeoff relationships between conflicting design objectives. The search results obtained from the reduced complexity multi-objective reservoir operation problems are then used to pre-condition the full search of the original optimization problem. In two case studies, the Dahuofang reservoir and the inter-basin multi-reservoir system in Liaoning province, China, sensitivity analysis results show that reservoir performance is strongly controlled by a small proportion of decision variables. Sensitivity-informed problem decomposition and pre-conditioning are evaluated in their ability to improve the efficiency and effectiveness of multi-objective evolutionary optimization. Overall, this study illustrates the efficiency and effectiveness of the sensitivity-informed method and the use of global sensitivity analysis to inform problem decomposition when solving the complex multi-objective reservoir operation problems.

An UPLC-ESI-MS/MS Assay Using 6-Aminoquinolyl-N-Hydroxysuccinimidyl Carbamate Derivatization for Targeted Amino Acid Analysis: Application to Screening of Arabidopsis thaliana Mutants.

PubMed

Salazar, Carolina; Armenta, Jenny M; Shulaev, Vladimir

2012-07-06

In spite of the large arsenal of methodologies developed for amino acid assessment in complex matrices, their implementation in metabolomics studies involving wide-ranging mutant screening is hampered by their lack of high-throughput, sensitivity, reproducibility, and/or wide dynamic range. In response to the challenge of developing amino acid analysis methods that satisfy the criteria required for metabolomic studies, improved reverse-phase high-performance liquid chromatography-mass spectrometry (RPHPLC-MS) methods have been recently reported for large-scale screening of metabolic phenotypes. However, these methods focus on the direct analysis of underivatized amino acids and, therefore, problems associated with insufficient retention and resolution are observed due to the hydrophilic nature of amino acids. It is well known that derivatization methods render amino acids more amenable for reverse phase chromatographic analysis by introducing highly-hydrophobic tags in their carboxylic acid or amino functional group. Therefore, an analytical platform that combines the 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) pre-column derivatization method with ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) is presented in this article. For numerous reasons typical amino acid derivatization methods would be inadequate for large scale metabolic projects. However, AQC derivatization is a simple, rapid and reproducible way of obtaining stable amino acid adducts amenable for UPLC-ESI-MS/MS and the applicability of the method for high-throughput metabolomic analysis in Arabidopsis thaliana is demonstrated in this study. Overall, the major advantages offered by this amino acid analysis method include high-throughput, enhanced sensitivity and selectivity; characteristics that showcase its utility for the rapid screening of the preselected plant metabolites without compromising the quality of the metabolic data. The presented method enabled thirty-eight metabolites (proteinogenic amino acids and related compounds) to be analyzed within 10 min with detection limits down to 1.02 × 10-11 M (i.e., atomole level on column), which represents an improved sensitivity of 1 to 5 orders of magnitude compared to existing methods. Our UPLC-ESI-MS/MS method is one of the seven analytical platforms used by the Arabidopsis Metabolomics Consortium. The amino acid dataset obtained by analysis of Arabidopsis T-DNA mutant stocks with our platform is captured and open to the public in the web portal PlantMetabolomics.org. The analytical platform herein described could find important applications in other studies where the rapid, high-throughput and sensitive assessment of low abundance amino acids in complex biosamples is necessary.

An UPLC-ESI-MS/MS Assay Using 6-Aminoquinolyl-N-Hydroxysuccinimidyl Carbamate Derivatization for Targeted Amino Acid Analysis: Application to Screening of Arabidopsis thaliana Mutants

PubMed Central

Salazar, Carolina; Armenta, Jenny M.; Shulaev, Vladimir

2012-01-01

In spite of the large arsenal of methodologies developed for amino acid assessment in complex matrices, their implementation in metabolomics studies involving wide-ranging mutant screening is hampered by their lack of high-throughput, sensitivity, reproducibility, and/or wide dynamic range. In response to the challenge of developing amino acid analysis methods that satisfy the criteria required for metabolomic studies, improved reverse-phase high-performance liquid chromatography-mass spectrometry (RPHPLC-MS) methods have been recently reported for large-scale screening of metabolic phenotypes. However, these methods focus on the direct analysis of underivatized amino acids and, therefore, problems associated with insufficient retention and resolution are observed due to the hydrophilic nature of amino acids. It is well known that derivatization methods render amino acids more amenable for reverse phase chromatographic analysis by introducing highly-hydrophobic tags in their carboxylic acid or amino functional group. Therefore, an analytical platform that combines the 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) pre-column derivatization method with ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) is presented in this article. For numerous reasons typical amino acid derivatization methods would be inadequate for large scale metabolic projects. However, AQC derivatization is a simple, rapid and reproducible way of obtaining stable amino acid adducts amenable for UPLC-ESI-MS/MS and the applicability of the method for high-throughput metabolomic analysis in Arabidopsis thaliana is demonstrated in this study. Overall, the major advantages offered by this amino acid analysis method include high-throughput, enhanced sensitivity and selectivity; characteristics that showcase its utility for the rapid screening of the preselected plant metabolites without compromising the quality of the metabolic data. The presented method enabled thirty-eight metabolites (proteinogenic amino acids and related compounds) to be analyzed within 10 min with detection limits down to 1.02 × 10−11 M (i.e., atomole level on column), which represents an improved sensitivity of 1 to 5 orders of magnitude compared to existing methods. Our UPLC-ESI-MS/MS method is one of the seven analytical platforms used by the Arabidopsis Metabolomics Consortium. The amino acid dataset obtained by analysis of Arabidopsis T-DNA mutant stocks with our platform is captured and open to the public in the web portal PlantMetabolomics.org. The analytical platform herein described could find important applications in other studies where the rapid, high-throughput and sensitive assessment of low abundance amino acids in complex biosamples is necessary. PMID:24957640

Functional design of electrolytic biosensor

NASA Astrophysics Data System (ADS)

Gamage Preethichandra, D. M.; Mala Ekanayake, E. M. I.; Onoda, M.

2017-11-01

A novel amperometric biosensbased on conjugated polypyrrole (PPy) deposited on a Pt modified ITO (indium tin oxide) conductive glass substrate and their performances are described. We have presented a method of developing a highly sensitive and low-cost nano-biosensor for blood glucose measurements. The fabrication method proposed decreases the cost of production significantly as the amount of noble metals used is minimized. A nano-corrugated PPy substrate was developed through pulsed electrochemical deposition. The sensitivity achieved was 325 mA/(Mcm2) and the linear range of the developed sensor was 50-60 mmol/l. Then the application of the electrophoresis helps the glucose oxidase (GOx) on the PPy substrate. The main reason behind this high enzyme loading is the high electric field applied across the sensor surface (working electrode) and the counter electrode where that pushes the nano-scale enzyme particles floating in the phosphate buffer solution towards the substrate. The novel technique used has provided an extremely high sensitivities and very high linear ranges for enzyme (GOx) and therefore can be concluded that this is a very good technique to load enzyme onto the conducting polymer substrates.

An Effective Electrical Resonance-Based Method to Detect Delamination in Thermal Barrier Coating

NASA Astrophysics Data System (ADS)

Kim, Jong Min; Park, Jae-Ha; Lee, Ho Girl; Kim, Hak-Joon; Song, Sung-Jin; Seok, Chang-Sung; Lee, Young-Ze

2017-12-01

This research proposes a simple yet highly sensitive method based on electrical resonance of an eddy-current probe to detect delamination of thermal barrier coating (TBC). This method can directly measure the mechanical characteristics of TBC compared to conventional ultrasonic testing and infrared thermography methods. The electrical resonance-based method can detect the delamination of TBC from the metallic bond coat by shifting the electrical impedance of eddy current testing (ECT) probe coupling with degraded TBC, and, due to this shift, the resonant frequencies near the peak impedance of ECT probe revealed high sensitivity to the delamination. In order to verify the performance of the proposed method, a simple experiment is performed with degraded TBC specimens by thermal cyclic exposure. Consequently, the delamination with growth of thermally grown oxide in a TBC system is experimentally identified. Additionally, the results are in good agreement with the results obtained from ultrasonic C-scanning.

An Effective Electrical Resonance-Based Method to Detect Delamination in Thermal Barrier Coating

NASA Astrophysics Data System (ADS)

Kim, Jong Min; Park, Jae-Ha; Lee, Ho Girl; Kim, Hak-Joon; Song, Sung-Jin; Seok, Chang-Sung; Lee, Young-Ze

2018-02-01

This research proposes a simple yet highly sensitive method based on electrical resonance of an eddy-current probe to detect delamination of thermal barrier coating (TBC). This method can directly measure the mechanical characteristics of TBC compared to conventional ultrasonic testing and infrared thermography methods. The electrical resonance-based method can detect the delamination of TBC from the metallic bond coat by shifting the electrical impedance of eddy current testing (ECT) probe coupling with degraded TBC, and, due to this shift, the resonant frequencies near the peak impedance of ECT probe revealed high sensitivity to the delamination. In order to verify the performance of the proposed method, a simple experiment is performed with degraded TBC specimens by thermal cyclic exposure. Consequently, the delamination with growth of thermally grown oxide in a TBC system is experimentally identified. Additionally, the results are in good agreement with the results obtained from ultrasonic C-scanning.

SU-E-T-315: The Change of Optically Stimulated Luminescent Dosimeters (OSLDs) Sensitivity by Accumulated Dose and High Dose

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

Han, S; Jung, H; Kim, M

2014-06-01

Purpose: The objective of this study is to evaluate radiation sensitivity of optical stimulated luminance dosimeters (OSLDs) by accumulated dose and high dose. Methods: This study was carried out in Co-60 unit (Theratron 780, AECL, and Canada) and used InLight MicroStar reader (Landauer, Inc., Glenwood, IL) for reading. We annealed for 30 min using optical annealing system which contained fluorescent lamps (Osram lumilux, 24 W, 280 ∼780 nm). To evaluate change of OSLDs sensitivity by repeated irradiation, the dosimeters were repeatedly irradiated with 1 Gy. And whenever a repeated irradiation, we evaluated OSLDs sensitivity. To evaluate OSLDs sensitivity after accumulatedmore » dose with 5 Gy, We irradiated dose accumulatively (from 1 Gy to 5 Gy) without annealing. And OSLDs was also irradiated with 15, 20, 30 Gy to certify change of OSLDs sensitivity after high dose irradiation. After annealing them, they were irradiated with 1Gy, repeatedly. Results: The OSLDs sensitivity increased up to 3% during irradiating seven times and decreased continuously above 8 times. That dropped by about 0.35 Gy per an irradiation. Finally, after 30 times irradiation, OSLDs sensitivity decreased by about 7%. For accumulated dose from 1 Gy to 5 Gy, OSLDs sensitivity about 1 Gy increased until 4.4% after second times accumulated dose compared with before that. OSLDs sensitivity about 1 Gy decreased by 1.6% in five times irradiation. When OSLDs were irradiated ten times with 1Gy after irradiating high dose (10, 15, 20 Gy), OSLDs sensitivity decreased until 6%, 9%, 12% compared with it before high dose irradiation, respectively. Conclusion: This study certified OSLDs sensitivity by accumulated dose and high dose. When irradiated with 1Gy, repeatedly, OSLDs sensitivity decreased linearly and the reduction rate of OSLDs sensitivity after high dose irradiation had dependence on irradiated dose.« less

GaAs-based resonant tunneling diode (RTD) epitaxy on Si for highly sensitive strain gauge applications

PubMed Central

2013-01-01

As a highly sensitive strain gauge element, GaAs-based resonant tunneling diode (RTD) has already been applied in microelectromechanical system (MEMS) sensors. Due to poor mechanical properties and high cost, GaAs-based material has been limited in applications as the substrate for MEMS. In this work, we present a method to fabricate the GaAs-based RTD on Si substrate. From the experimental results, it can be concluded that the piezoresistive coefficient achieved with this method reached 3.42 × 10−9 m2/N, which is about an order of magnitude higher than the Si-based semiconductor piezoresistors. PMID:23651496

A novel quantitative analysis method of three-dimensional fluorescence spectra for vegetable oils contents in edible blend oil

NASA Astrophysics Data System (ADS)

Xu, Jing; Wang, Yu-Tian; Liu, Xiao-Fei

2015-04-01

Edible blend oil is a mixture of vegetable oils. Eligible blend oil can meet the daily need of two essential fatty acids for human to achieve the balanced nutrition. Each vegetable oil has its different composition, so vegetable oils contents in edible blend oil determine nutritional components in blend oil. A high-precision quantitative analysis method to detect the vegetable oils contents in blend oil is necessary to ensure balanced nutrition for human being. Three-dimensional fluorescence technique is high selectivity, high sensitivity, and high-efficiency. Efficiency extraction and full use of information in tree-dimensional fluorescence spectra will improve the accuracy of the measurement. A novel quantitative analysis is proposed based on Quasi-Monte-Carlo integral to improve the measurement sensitivity and reduce the random error. Partial least squares method is used to solve nonlinear equations to avoid the effect of multicollinearity. The recovery rates of blend oil mixed by peanut oil, soybean oil and sunflower are calculated to verify the accuracy of the method, which are increased, compared the linear method used commonly for component concentration measurement.

Genetics and clinical response to warfarin and edoxaban in patients with venous thromboembolism

PubMed Central

Vandell, Alexander G; Walker, Joseph; Brown, Karen S; Zhang, George; Lin, Min; Grosso, Michael A; Mercuri, Michele F

2017-01-01

Objective The aim of this study was to investigate whether genetic variants can identify patients with venous thromboembolism (VTE) at an increased risk of bleeding with warfarin. Methods Hokusai-venous thromboembolism (Hokusai VTE), a randomised, multinational, double-blind, non-inferiority trial, evaluated the safety and efficacy of edoxaban versus warfarin in patients with VTE initially treated with heparin. In this subanalysis of Hokusai VTE, patients genotyped for variants in CYP2C9 and VKORC1 genes were divided into three warfarin sensitivity types (normal, sensitive and highly sensitive) based on their genotypes. An exploratory analysis was also conducted comparing normal responders to pooled sensitive responders (ie, sensitive and highly sensitive responders). Results The analysis included 47.7% (3956/8292) of the patients in Hokusai VTE. Among 1978 patients randomised to warfarin, 63.0% (1247) were normal responders, 34.1% (675) were sensitive responders and 2.8% (56) were highly sensitive responders. Compared with normal responders, sensitive and highly sensitive responders had heparin therapy discontinued earlier (p<0.001), had a decreased final weekly warfarin dose (p<0.001), spent more time overanticoagulated (p<0.001) and had an increased bleeding risk with warfarin (sensitive responders HR 1.38 [95% CI 1.11 to 1.71], p=0.0035; highly sensitive responders 1.79 [1.09 to 2.99]; p=0.0252). Conclusion In this study, CYP2C9 and VKORC1 genotypes identified patients with VTE at increased bleeding risk with warfarin. Trial registration number NCT00986154. PMID:28689179

[The history of hepatitis B virus-related determination tests and inspection and the measurements of problems in Japan].

PubMed

Shibata, Hiroshi

2013-09-01

Since Hepatitis B virus was detected as the cause of hepatitis, many high-sensitive measurement methods have been developed. In the development history, there are many problems in accuracy, sensitivity and health insurance regulations among different types of kits with different measurement principles. Advanced medical treatments cause problems of gene mutation or reactivation of HBV, leading to the necessity for high sensitive and sophisticated determination. The history of clinical analysis for the detection of HBV was reviewed from the viewpoint of our experiences.

Analytical Glycobiology at High Sensitivity: Current Approaches and Directions

PubMed Central

Novotny, Milos V.; Alley, William R.; Mann, Benjamin F.

2013-01-01

This review summarizes the analytical advances made during the last several years in the structural and quantitative determinations of glycoproteins in complex biological mixtures. The main analytical techniques used in the fields of glycomics and glycoproteomics involve different modes of mass spectrometry and their combinations with capillary separation methods such as microcolumn liquid chromatography and capillary electrophoresis. The needs for high-sensitivity measurements have been emphasized in the oligosaccharide profiling used in the field of biomarker discovery through MALDI mass spectrometry. High-sensitivity profiling of both glycans and glycopeptides from biological fluids and tissue extracts has been aided significantly through lectin preconcentration and the uses of affinity chromatography. PMID:22945852

Simultaneous ultramicroanalysis of both 17-keto-and 17beta-hydroxy androgens in biological fluids.

PubMed

Ganjam, V K

1976-11-01

Sensitive methods for quantifying androgens were lacking. Therefore, a relatively simple procedure for separating steroids was combined with highly specific assay methods so that eight androgens could be measured with high accuracy, precision and sensitivity. Semi-automated separations on Sephadex LH-20 columns used heptane:methylene chloride:ethanol:water (50:50:1:0.12) and a flow rate of 17.0 min/ml. The six peaks eluted contained androstenedine; androsterone, epiandrosterone and dihydrotestosterone; testosterone and dehydroepiandrosterone; 3alpha-androstanediol; 3beta-androstanediol; and androstenediol. Androstenedione, dehydroepiandrosterone and androstenediol were quantified using specific antisera (sensitivity less than or equal to 75 pg). Testosterone and dihydrotestosterone were measured by competitive protein-binding assays using rabbit TeBG (sensitivity less than or equal to 150 pg). 3alpha- and 3beta-androstanediol were similarly assayed using human TeBG (sensitivity approximately 150 pg). Androsterone was reduced with NaBH4 and the resulting 3alpha-androstanediol was assayed using human TeBG (sensitivity approximately 200 pg). Inter- and intra-assay variations were less than 10% for radioimmunoassays and less than 16% for competitive protein-binding assays over the entire dose response curve.

Development of a highly sensitive and specific ELISA method for the determination of l-corydalmine in SD rats with monoclonal antibody.

PubMed

Zhang, Hongwei; Gao, Lan; Shu, Menglin; Liu, Jihua; Yu, Boyang

2018-01-15

l-Corydalmine (l-CDL) is a potent analgesic constituent of the traditional Chinese medicine, Rhizoma Corydalis. However, the pharmacokinetic process and tissue distribution of l-CDL in vivo are still unknown. Therefore, it is necessary to establish a simple and sensitive method to detect l-CDL, which will be helpful to study its distribution and pharmacokinetic process. To determine this compound in biological samples, a monoclonal antibody (mAb) against l-CDL was produced and a fast and highly sensitive indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed in this study. The icELISA was applied to determine l-CDL in biological samples. The limit of detection (LOD) of the method was 0.015 ng/mL with a liner range of 1-1000 ng/mL (R 2  = 0.9912). The intra- and inter-day precision were below 15% and the recoveries were within 80-117%. Finally, the developed immunoassay was successfully applied to the analysis of the distribution of l-CDL in SD rats. In conclusion, the icELISA based on the anti-l-CDL mAb could be considered as a highly sensitive and rapid method for the determination of l-CDL in biological samples. The ELISA approach may provide a valuable tool for the analysis of small molecules in biological samples. Copyright © 2017. Published by Elsevier B.V.

Small-displacement sensing system based on multiple total internal reflections in heterodyne interferometry.

PubMed

Wang, Shinn-Fwu; Chiu, Ming-Hung; Chen, Wei-Wu; Kao, Fu-Hsi; Chang, Rong-Seng

2009-05-01

A small-displacement sensing system based on multiple total internal reflections in heterodyne interferometry is proposed. In this paper, a small displacement can be obtained only by measuring the variation in phase difference between s- and p-polarization states for the total internal reflection effect. In order to improve the sensitivity, we increase the number of total internal reflections by using a parallelogram prism. The theoretical resolution of the method is better than 0.417 nm. The method has some merits, e.g., high resolution, high sensitivity, and real-time measurement. Also, its feasibility is demonstrated.

Signal processing system for electrotherapy applications

NASA Astrophysics Data System (ADS)

Płaza, Mirosław; Szcześniak, Zbigniew

2017-08-01

The system of signal processing for electrotherapeutic applications is proposed in the paper. The system makes it possible to model the curve of threshold human sensitivity to current (Dalziel's curve) in full medium frequency range (1kHz-100kHz). The tests based on the proposed solution were conducted and their results were compared with those obtained according to the assumptions of High Tone Power Therapy method and referred to optimum values. Proposed system has high dynamics and precision of mapping the curve of threshold human sensitivity to current and can be used in all methods where threshold curves are modelled.

An efficient method of reducing glass dispersion tolerance sensitivity

NASA Astrophysics Data System (ADS)

Sparrold, Scott W.; Shepard, R. Hamilton

2014-12-01

Constraining the Seidel aberrations of optical surfaces is a common technique for relaxing tolerance sensitivities in the optimization process. We offer an observation that a lens's Abbe number tolerance is directly related to the magnitude by which its longitudinal and transverse color are permitted to vary in production. Based on this observation, we propose a computationally efficient and easy-to-use merit function constraint for relaxing dispersion tolerance sensitivity. Using the relationship between an element's chromatic aberration and dispersion sensitivity, we derive a fundamental limit for lens scale and power that is capable of achieving high production yield for a given performance specification, which provides insight on the point at which lens splitting or melt fitting becomes necessary. The theory is validated by comparing its predictions to a formal tolerance analysis of a Cooke Triplet, and then applied to the design of a 1.5x visible linescan lens to illustrate optimization for reduced dispersion sensitivity. A selection of lenses in high volume production is then used to corroborate the proposed method of dispersion tolerance allocation.

Simple, Sensitive and Accurate Multiplex Detection of Clinically Important Melanoma DNA Mutations in Circulating Tumour DNA with SERS Nanotags

PubMed Central

Wee, Eugene J.H.; Wang, Yuling; Tsao, Simon Chang-Hao; Trau, Matt

2016-01-01

Sensitive and accurate identification of specific DNA mutations can influence clinical decisions. However accurate diagnosis from limiting samples such as circulating tumour DNA (ctDNA) is challenging. Current approaches based on fluorescence such as quantitative PCR (qPCR) and more recently, droplet digital PCR (ddPCR) have limitations in multiplex detection, sensitivity and the need for expensive specialized equipment. Herein we describe an assay capitalizing on the multiplexing and sensitivity benefits of surface-enhanced Raman spectroscopy (SERS) with the simplicity of standard PCR to address the limitations of current approaches. This proof-of-concept method could reproducibly detect as few as 0.1% (10 copies, CV < 9%) of target sequences thus demonstrating the high sensitivity of the method. The method was then applied to specifically detect three important melanoma mutations in multiplex. Finally, the PCR/SERS assay was used to genotype cell lines and ctDNA from serum samples where results subsequently validated with ddPCR. With ddPCR-like sensitivity and accuracy yet at the convenience of standard PCR, we believe this multiplex PCR/SERS method could find wide applications in both diagnostics and research. PMID:27446486

Simple, Sensitive and Accurate Multiplex Detection of Clinically Important Melanoma DNA Mutations in Circulating Tumour DNA with SERS Nanotags.

PubMed

Wee, Eugene J H; Wang, Yuling; Tsao, Simon Chang-Hao; Trau, Matt

2016-01-01

Sensitive and accurate identification of specific DNA mutations can influence clinical decisions. However accurate diagnosis from limiting samples such as circulating tumour DNA (ctDNA) is challenging. Current approaches based on fluorescence such as quantitative PCR (qPCR) and more recently, droplet digital PCR (ddPCR) have limitations in multiplex detection, sensitivity and the need for expensive specialized equipment. Herein we describe an assay capitalizing on the multiplexing and sensitivity benefits of surface-enhanced Raman spectroscopy (SERS) with the simplicity of standard PCR to address the limitations of current approaches. This proof-of-concept method could reproducibly detect as few as 0.1% (10 copies, CV < 9%) of target sequences thus demonstrating the high sensitivity of the method. The method was then applied to specifically detect three important melanoma mutations in multiplex. Finally, the PCR/SERS assay was used to genotype cell lines and ctDNA from serum samples where results subsequently validated with ddPCR. With ddPCR-like sensitivity and accuracy yet at the convenience of standard PCR, we believe this multiplex PCR/SERS method could find wide applications in both diagnostics and research.

Obtaining changes in calibration-coil to seismometer output constants using sine waves

USGS Publications Warehouse

Ringler, Adam T.; Hutt, Charles R.; Gee, Lind S.; Sandoval, Leo D.; Wilson, David C.

2013-01-01

The midband sensitivity of a broadband seismometer is one of the most commonly used parameters from station metadata. Thus, it is critical for station operators to robustly estimate this quantity with a high degree of accuracy. We develop an in situ method for estimating changes in sensitivity using sine‐wave calibrations, assuming the calibration coil and its drive are stable over time and temperature. This approach has been used in the past for passive instruments (e.g., geophones) but has not been applied, to our knowledge, to derive sensitivities of modern force‐feedback broadband seismometers. We are able to detect changes in sensitivity to well within 1%, and our method is capable of detecting these sensitivity changes using any frequency of sine calibration within the passband of the instrument.

Highly sensitive troponin T for risk stratification of acutely destabilized heart failure.

PubMed

Pascual-Figal, Domingo A; Casas, Teresa; Ordonez-Llanos, Jordi; Manzano-Fernández, Sergio; Bonaque, Juan C; Boronat, Miguel; Muñoz-Esparza, Carmen; Valdés, Mariano; Januzzi, James L

2012-06-01

A highly sensitive assay for troponin T (hsTnT) has been recently developed, which allows for the detection of even minor myocardial necrosis with high precision. It remains unexplored whether hsTnT provides incremental prognostic accuracy beyond conventional (c)TnT in patients with acutely decompensated heart failure (ADHF). A total of 202 consecutive patients admitted with ADHF and without criteria for acute myocardial infarction were studied. Troponin T was measured using the highly sensitive assay and compared with the conventional method. Patients were clinically followed up at a median of 406 days, with a primary outcome measure of all-cause mortality. The high-sensitive assay detected measurable TnT in 98% of patients vs 56% for cTnT; 81% had an hsTnT above the 99th percentile for a healthy reference population, and it reclassified 60% of those with undetectable cTnT. Both TnT methods predicted the risk of death in adjusted multivariable Cox regression analyses, without a superiority of hsTnT over cTnT in the entire population (area under the curve 0.67 vs 0.71, P = .2). Among patients with a cTnT below 0.03 ng/mL (the lowest cut-point with <10% imprecision; n = 134), solely hsTnT improved the prediction of death over clinical risk factors (relative integrated discrimination improvement +36%, P = .01) and hsTnT above 20 pg/mL identified a significant higher risk of death (hazard ratio 4.7, 95% CI 1.6-13.8, P = .005). Among patients with ADHF, myocardial necrosis (as detected with the hsTnT assay) was nearly ubiquitous. The highly sensitive assay for TnT provides comparable prognostic information to cTnT overall, but among those in whom the cTnT method was less precise or frankly negative, the hsTnT assay provided prognostic information. Copyright © 2012 Mosby, Inc. All rights reserved.

Highly sensitive detection of dipicolinic acid with a water-dispersible terbium-metal organic framework.

PubMed

Bhardwaj, Neha; Bhardwaj, Sanjeev; Mehta, Jyotsana; Kim, Ki-Hyun; Deep, Akash

2016-12-15

The sensitive detection of dipicolinic acid (DPA) is strongly associated with the sensing of bacterial organisms in food and many types of environmental samples. To date, the demand for a sensitive detection method for bacterial toxicity has increased remarkably. Herein, we investigated the DPA detection potential of a water-dispersible terbium-metal organic framework (Tb-MOF) based on the fluorescence quenching mechanism. The Tb-MOF showed a highly sensitive ability to detect DPA at a limit of detection of 0.04nM (linear range of detection: 1nM to 5µM) and also offered enhanced selectivity from other commonly associated organic molecules. The present study provides a basis for the application of Tb-MOF for direct, convenient, highly sensitive, and specific detection of DPA in the actual samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Groundwater sensitivity mapping in Kentucky using GIS and digitally vectorized geologic quadrangles

NASA Astrophysics Data System (ADS)

Croskrey, Andrea; Groves, Chris

2008-05-01

Groundwater sensitivity (Ray and O’dell in Environ Geol 22:345 352, 1993a) refers to the inherent ease with which groundwater can be contaminated based on hydrogeologic characteristics. We have developed digital methods for identifying areas of varying groundwater sensitivity for a ten county area of south central Kentucky at a scale of 1:100,000. The study area includes extensive limestone karst sinkhole plains, with groundwater extremely sensitive to contamination. Digitally vectorized geologic quadrangles (DVGQs) were combined with elevation data to identify both hydrogeologic groundwater sensitivity regions and zones of “high risk runoff” where contaminants could be transported in runoff from less sensitive to higher sensitivity (particularly karst) areas. While future work will fine-tune these maps with additional layers of data (soils for example) as digital data have become available, using DVGQs allows a relatively rapid assessment of groundwater sensitivity for Kentucky at a more useful scale than previously available assessment methods, such as DRASTIC and DIVERSITY.

Meat authentication: a new HPLC-MS/MS based method for the fast and sensitive detection of horse and pork in highly processed food.

PubMed

von Bargen, Christoph; Brockmeyer, Jens; Humpf, Hans-Ulrich

2014-10-01

Fraudulent blending of food products with meat from undeclared species is a problem on a global scale, as exemplified by the European horse meat scandal in 2013. Routinely used methods such as ELISA and PCR can suffer from limited sensitivity or specificity when processed food samples are analyzed. In this study, we have developed an optimized method for the detection of horse and pork in different processed food matrices using MRM and MRM(3) detection of species-specific tryptic marker peptides. Identified marker peptides were sufficiently stable to resist thermal processing of different meat products and thus allow the sensitive and specific detection of pork or horse in processed food down to 0.24% in a beef matrix system. In addition, we were able to establish a rapid 2-min extraction protocol for the efficient protein extraction from processed food using high molar urea and thiourea buffers. Together, we present here the specific and sensitive detection of horse and pork meat in different processed food matrices using MRM-based detection of marker peptides. Notably, prefractionation of proteins using 2D-PAGE or off-gel fractionation is not necessary. The presented method is therefore easily applicable in analytical routine laboratories without dedicated proteomics background.

A sensitive and efficient method for determination of N-acetylhexosamines and N-acetylneuraminic acid in breast milk and milk-based products by high-performance liquid chromatography via UV detection and mass spectrometry identification.

PubMed

Chuanxiang, Wu; Lian, Xia; Lijie, Liu; Fengli, Qu; Zhiwei, Sun; Xianen, Zhao; Jinmao, You

2016-02-01

A sensitive and efficient method of high performance liquid chromatography using 1-(2-naphthyl)-3-methyl-5-pyrazolone (NMP) as pre-column derivatization reagent coupled with UV detection (HPLC-UV) and online mass spectrometry identification was established for determination of the most common N-Acetylhexosamines (N-acetyl-d-glucosamine (GlcNAc) and N-acetyl-d-galactosamine (GalNAc)) and N-acetylneuraminic acid (Neu5Ac). In order to obtain the highest liberation level of the three monosaccharides without destruction of Neu5Ac or conversion of GlcNAc/GalNAc to GlcN/GalN in the hydrolysis procedure, the pivotal parameters affecting the liberation of N-acetylhexosamines/Neu5Ac from sample were investigated with response surface methodology (RSM). Under the optimized condition, maximum yield was obtained. The effects of key parameters on derivatization, separation and detection were also investigated. At optimized conditions, three monosaccharides were labeled fast and entirely, and all derivatives exhibited a good baseline resolution and high detection sensitivity. The developed method was linear over the calibration range 0.25-12μM, with R(2)>0.9991. The detection limits of the method were between 0.48 and 2.01pmol. Intra- and inter-day precisions for the three monosaccharides (GlcNAc, GalNAc and Neu5Ac) were found to be in the range of 3.07-4.02% and 3.69-4.67%, respectively. Individual monosaccharide recovery from spiked milk was in the range of 81%-97%. The sensitivity of the method, the facility of the derivatization procedure and the reliability of the hydrolysis conditions suggest the proposed method has a high potential for utilization in routine trace N-acetylhexosamines and Neu5Ac analysis in biological samples. Copyright © 2015 Elsevier B.V. All rights reserved.

High-sensitivity pH sensor using separative extended-gate field-effect transistors with single-walled carbon-nanotube networks

NASA Astrophysics Data System (ADS)

Pyo, Ju-Young; Cho, Won-Ju

2018-04-01

We fabricate high-sensitivity pH sensors using single-walled carbon-nanotube (SWCNT) network thin-film transistors (TFTs). The sensing and transducer parts of the pH sensor are composed of separative extended-sensing gates (ESGs) with SnO2 ion-sensitive membranes and double-gate structure TFTs with thin SWCNT network channels of ∼1 nm and AlO x top-gate insulators formed by the solution-deposition method. To prevent thermal process-induced damages on the SWCNT channel layer due to the post-deposition annealing process and improve the electrical characteristics of the SWCNT-TFTs, microwave irradiation is applied at low temperatures. As a result, a pH sensitivity of 7.6 V/pH, far beyond the Nernst limit, is obtained owing to the capacitive coupling effect between the top- and bottom-gate insulators of the SWCNT-TFTs. Therefore, double-gate structure SWCNT-TFTs with separated ESGs are expected to be highly beneficial for high-sensitivity disposable biosensor applications.

Biomimetic self-templating optical structures fabricated by genetically engineered M13 bacteriophage.

PubMed

Kim, Won-Geun; Song, Hyerin; Kim, Chuntae; Moon, Jong-Sik; Kim, Kyujung; Lee, Seung-Wuk; Oh, Jin-Woo

2016-11-15

Here, we describe a highly sensitive and selective surface plasmon resonance sensor system by utilizing self-assembly of genetically engineered M13 bacteriophage. About 2700 copies of genetically expressed peptide copies give superior selectivity and sensitivity to M13 phage-based SPR sensor. Furthermore, the sensitivity of the M13 phage-based SPR sensor was enhanced due to the aligning of receptor matrix in specific direction. Incorporation of specific binding peptide (His Pro Gln: HPQ) gives M13 bacteriophage high selectivity for the streptavidin. Our M13 phage-based SPR sensor takes advantage of simplicity of self-assembly compared with relatively complex photolithography techniques or chemical conjugations. Additionally, designed structure which is composed of functionalized M13 bacteriophage can simultaneously improve the sensitivity and selectivity of SPR sensor evidently. By taking advantages of the genetic engineering and self-assembly, we propose the simple method for fabricating novel M13 phage-based SPR sensor system which has a high sensitivity and high selectivity. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of four 5-hydroxy polymethoxyflavones by reversed-phase high performance liquid chromatography with electrochemical detection.

PubMed

Dong, Ping; Qiu, Peiju; Zhu, Yi; Li, Shiming; Ho, Chi-Tang; McClements, David Julian; Xiao, Hang

2010-01-29

Accumulating evidence has suggested the potential health-promoting effects of 5-hydroxy polymethoxyflavones (5-OH-PMFs) naturally existing in citrus genus. However, research efforts are hampered by the lack of reliable and sensitive methods for their determination in plant materials and biological samples. Using reversed-phase high performance liquid chromatography (HPLC) equipped with electrochemical (EC) detection, we have developed a fast and highly sensitive method for quantification of four 5-OH-PMFs, namely 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone, 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone, 5-hydroxy-6,7,4'-trimethoxyflavone, and 5-hydroxy-6,7,8,4'-tetramethoxyflavone. The method was fully validated in terms of linearity, accuracy and precision. The limit of detection (LOD) was determined as being between 0.65 and 1.8ng/mL (ppb), demonstrating an over 160 times higher sensitivity in comparison with the previously reported method using UV detection. The recovery rate of the method was between 96.17% and 110.82%, and the precision for the retention times and peak areas was all below 13%. The method was successfully used to quantify 5-OH-PMFs with a wide range of abundance in the citrus products and preparations, such as orange juice, citrus peel, and dried tangerine peel. The quantification method for 5-OH-PMFs developed herein could be useful for the nutritional and pharmacological studies of these compounds in future. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Low angle light scattering analysis: a novel quantitative method for functional characterization of human and murine platelet receptors.

PubMed

Mindukshev, Igor; Gambaryan, Stepan; Kehrer, Linda; Schuetz, Claudia; Kobsar, Anna; Rukoyatkina, Natalia; Nikolaev, Viacheslav O; Krivchenko, Alexander; Watson, Steve P; Walter, Ulrich; Geiger, Joerg

2012-07-01

Determinations of platelet receptor functions are indispensable diagnostic indicators of cardiovascular and hemostatic diseases including hereditary and acquired receptor defects and receptor responses to drugs. However, presently available techniques for assessing platelet function have some disadvantages, such as low sensitivity and the requirement of large sample sizes and unphysiologically high agonist concentrations. Our goal was to develop and initially characterize a new technique designed to quantitatively analyze platelet receptor activation and platelet function on the basis of measuring changes in low angle light scattering. We developed a novel technique based on low angle light scattering registering changes in light scattering at a range of different angles in platelet suspensions during activation. The method proved to be highly sensitive for simultaneous real time detection of changes in size and shape of platelets during activation. Unlike commonly-used methods, the light scattering method could detect platelet shape change and aggregation in response to nanomolar concentrations of extracellular nucleotides. Furthermore, our results demonstrate that the advantages of the light scattering method make it a choice method for platelet receptor monitoring and for investigation of both murine and human platelets in disease models. Our data demonstrate the suitability and superiority of this new low angle light scattering method for comprehensive analyses of platelet receptors and functions. This highly sensitive, quantitative, and online detection of essential physiological, pathophysiological and pharmacological-response properties of human and mouse platelets is a significant improvement over conventional techniques.

Immunohistochemistry and Polymerase Chain Reaction for Detection Human Papilloma Virus in Warts: A Comparative Study

PubMed Central

Lee, Hong Sun; Lee, Ji Hyun; Choo, Ji Yoon; Byun, Hee Jin; Jun, Jin Hyun

2016-01-01

Background Immunohistochemistry and polymerase chain reaction (PCR) are the most widely used methods for the detection of viruses. PCR is known to be a more sensitive and specific method than the immunohistochemical method at this time, but PCR has the disadvantages of high cost and skilled work to use widely. With the progress of technology, the immunohistochemical methods used in these days has come to be highly sensitive and actively used in the diagnostic fields. Objective To evaluate and compare the usefulness of immunohistochemistry and PCR for detection human papilloma virus (HPV) in wart lesions. Methods Nine biopsy samples of verruca vulgaris and 10 of condyloma accuminatum were examined. Immunohistochemical staining using monoclonal antibody to HPV L1 capsid protein and PCR were done for the samples. DNA sequencing of the PCR products and HPV genotyping were also done. Results HPV detection rate was 78.9% (88.9% in verruca vulgaris, 70.0% in condyloma accuminatum) on immunohistochemistry and 100.0% for PCR. HPV-6 genotype showed a lower positivity rate on immunohistochemistry (50.0%) as compared to that of the other HPV genotypes. Conclusion Immunohistochemistry for HPV L1 capsid protein showed comparable sensitivity for detection HPV. Considering the high cost and great effort needed for the PCR methods, we can use immunohistochemistry for HPV L1 capsid protein with the advantage of lower cost and simple methods for HPV detection. PMID:27489431

Development of a highly specific enzyme immunoassay for oxytocin and its use in plasma samples.

PubMed

Haraya, Shiomi; Karasawa, Koji; Sano, Yoshihiro; Ozawa, Kimiko; Kato, Nobumasa; Arakawa, Hidetoshi

2017-01-01

Background The peptide hormone oxytocin acts in the central nervous system and plays an important role in various complex social behaviours. We report the production of a high affinity and specificity antibody for oxytocin and its use in a highly sensitive enzyme immunoassay. Biotin that was chemically bound to oxytocin derivative containing zero to six lysines as bridge was the labelled antigen. Seven labelled antigens were used to develop a highly sensitive enzyme immunoassay. Methods Antioxytocin antiserum was obtained by immunization of oxytocin-bovine thyrogloblin conjugate to rabbit. Oxytocin sample was added to the second antibody-coated microtitre plate and allowed to react overnight at 4℃, then biotinylated oxytocin was added 1 h at 4℃, and horseradish peroxidase-labelled avidin was added and incubated for 1 h at room temperature. The plate was then washed. Horseradish peroxidase activity was measured by a colorimetric method using o-phenylenediamine (490 nm). Results The sensitivity of the enzyme immunoassay improved as the number of lysine residues increased; consequently, biotinylated oxytocin bridged with five lysines was used. A standard curve for oxytocin ranged from 1.0 to 1000 pg/assay. The detection limit of the assay was 2.36 pg, and the reproducibility was 3.6% as CV% ( n = 6). Cross-reactivity with vasopressin and vasotocin was less than 0.01%. Conclusion The sensitivity of the enzyme immunoassay could be improved by increasing the number of lysine residues on the biotin-labelled antigen. The proposed method is sensitive and more specific than conventional immunoassays for oxytocin and can be used to determine plasma oxytocin concentrations.

Measurement of Plasma Nitrite by Chemiluminescence without Interference of S-, N-nitroso and Nitrated Species

PubMed Central

Nagababu, Enika; Rifkind, Joseph M.

2009-01-01

Recent studies have demonstrated that plasma nitrite (NO2-) reflects endothelial nitric oxide synthase activity and it has been proposed as a prognostic marker for cardiovascular disease. In addition, NO2- itself has been shown to have biological activities thought to be triggered by reduction back to NO in blood and tissues. The development of sensitive and reproducible methods for the quantitative determination of plasma NO2- is, therefore, of great importance. Ozone-based chemiluminescence assays have been shown to be highly sensitive for the determination of nanomolar quantities of NO and NO related species in biological fluids. We report here an improved direct chemiluminescence method for the determination of plasma NO2- without interference of other nitric oxide related species such as nitrate, S-nitrosothiols, N-nitrosamines, nitrated proteins and nitrated lipids. The method involves a reaction system consisting of glacial acetic acid and ascorbic acid in the purge vessel of the NO analyzer. Under these acidic conditions NO2- is stoichiometrically reduced to NO by ascorbic acid. Fasting human plasma NO2- values were found in the range of 56-210 nM (mean =110 ± 36 nM). This method has high sensitivity with an accuracy of 97% and high precision (C.V <10%) for determination of plasma nitrite. The present method is simple and highly specific for plasma NO2-. It is particularly suited to evaluate vasculature endothelial NO production that predicts the risks for cardiovascular disease. PMID:17382196

Self-Assembled ZnO Nanosheet-Based Spherical Structure as Photoanode in Dye-Sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Ameri, Mohsen; Raoufi, Meysam; Zamani-Meymian, M.-R.; Samavat, Feridoun; Fathollahi, M.-R.; Mohajerani, Ezeddin

2018-03-01

High surface area and enhanced light scattering of ZnO nanosheet aggregates have made them a promising active layer candidate material for fabrication of nanostructure dye-sensitized solar cells. Here, we propose a facile preparation method of such ZnO nanosheet structures, and in order to verify their applicability as photoanode material for dye-sensitized solar cells, we employ morphological, optical, structural and electrical measurements. The results reveal the high surface area available for dye molecules for enhancing adsorption, high light scattering and competitive power conversion efficiencies compared to the works in literature. Finally, the device is optimized with respect to the photoanode thickness. The favorable features shown here can extend the application of the structure to other types of sensitization-based perovskite and quantum dot solar cells.

Highly sensitive simultaneous quantification of estrogenic tamoxifen metabolites and steroid hormones by LC-MS/MS.

PubMed

Johänning, Janina; Heinkele, Georg; Precht, Jana C; Brauch, Hiltrud; Eichelbaum, Michel; Schwab, Matthias; Schroth, Werner; Mürdter, Thomas E

2015-09-01

Tamoxifen is a mainstay in the treatment of estrogen receptor-positive breast cancer and is metabolized to more than 30 different compounds. Little is known about in vivo concentrations of estrogenic metabolites E-metabolite E, Z-metabolite E, and bisphenol and their relevance for tamoxifen efficacy. Therefore, we developed a highly sensitive HPLC-ESI-MS/MS quantification method for tamoxifen metabolites bisphenol, E-metabolite E, and Z-metabolite E as well as for the sex steroid hormones estradiol, estrone, testosterone, androstenedione, and progesterone. Plasma samples were subjected to protein precipitation followed by solid phase extraction. Upon derivatization with 3-[(N-succinimide-1-yl)oxycarbonyl]-1-methylpyridinium iodide, all analytes were separated on a sub-2-μm column with a gradient of acetonitrile in water with 0.1 % of formic acid. Analytes were detected on a triple-quadrupole mass spectrometer with positive electrospray ionization in the multiple reaction monitoring mode. Our method demonstrated high sensitivity, accuracy, and precision. The lower limits of quantification were 12, 8, and 25 pM for bisphenol, E-metabolite E, and Z-metabolite E, respectively, and 4 pM for estradiol and estrogen, 50 pM for testosterone and androstenedione, and 25 pM for progesterone. The method was applied to plasma samples of postmenopausal patients taken at baseline and under tamoxifen therapy. Graphical Abstract Sample preparation and derivatization for highly sensitive quantification of estrogenic tamoxifen metabolites and steroid hormones by HPLC-MS/MS.

Data mining methods in the prediction of Dementia: A real-data comparison of the accuracy, sensitivity and specificity of linear discriminant analysis, logistic regression, neural networks, support vector machines, classification trees and random forests

PubMed Central

2011-01-01

Background Dementia and cognitive impairment associated with aging are a major medical and social concern. Neuropsychological testing is a key element in the diagnostic procedures of Mild Cognitive Impairment (MCI), but has presently a limited value in the prediction of progression to dementia. We advance the hypothesis that newer statistical classification methods derived from data mining and machine learning methods like Neural Networks, Support Vector Machines and Random Forests can improve accuracy, sensitivity and specificity of predictions obtained from neuropsychological testing. Seven non parametric classifiers derived from data mining methods (Multilayer Perceptrons Neural Networks, Radial Basis Function Neural Networks, Support Vector Machines, CART, CHAID and QUEST Classification Trees and Random Forests) were compared to three traditional classifiers (Linear Discriminant Analysis, Quadratic Discriminant Analysis and Logistic Regression) in terms of overall classification accuracy, specificity, sensitivity, Area under the ROC curve and Press'Q. Model predictors were 10 neuropsychological tests currently used in the diagnosis of dementia. Statistical distributions of classification parameters obtained from a 5-fold cross-validation were compared using the Friedman's nonparametric test. Results Press' Q test showed that all classifiers performed better than chance alone (p < 0.05). Support Vector Machines showed the larger overall classification accuracy (Median (Me) = 0.76) an area under the ROC (Me = 0.90). However this method showed high specificity (Me = 1.0) but low sensitivity (Me = 0.3). Random Forest ranked second in overall accuracy (Me = 0.73) with high area under the ROC (Me = 0.73) specificity (Me = 0.73) and sensitivity (Me = 0.64). Linear Discriminant Analysis also showed acceptable overall accuracy (Me = 0.66), with acceptable area under the ROC (Me = 0.72) specificity (Me = 0.66) and sensitivity (Me = 0.64). The remaining classifiers showed overall classification accuracy above a median value of 0.63, but for most sensitivity was around or even lower than a median value of 0.5. Conclusions When taking into account sensitivity, specificity and overall classification accuracy Random Forests and Linear Discriminant analysis rank first among all the classifiers tested in prediction of dementia using several neuropsychological tests. These methods may be used to improve accuracy, sensitivity and specificity of Dementia predictions from neuropsychological testing. PMID:21849043

Method-independent, Computationally Frugal Convergence Testing for Sensitivity Analysis Techniques

NASA Astrophysics Data System (ADS)

Mai, Juliane; Tolson, Bryan

2017-04-01

The increasing complexity and runtime of environmental models lead to the current situation that the calibration of all model parameters or the estimation of all of their uncertainty is often computationally infeasible. Hence, techniques to determine the sensitivity of model parameters are used to identify most important parameters or model processes. All subsequent model calibrations or uncertainty estimation procedures focus then only on these subsets of parameters and are hence less computational demanding. While the examination of the convergence of calibration and uncertainty methods is state-of-the-art, the convergence of the sensitivity methods is usually not checked. If any, bootstrapping of the sensitivity results is used to determine the reliability of the estimated indexes. Bootstrapping, however, might as well become computationally expensive in case of large model outputs and a high number of bootstraps. We, therefore, present a Model Variable Augmentation (MVA) approach to check the convergence of sensitivity indexes without performing any additional model run. This technique is method- and model-independent. It can be applied either during the sensitivity analysis (SA) or afterwards. The latter case enables the checking of already processed sensitivity indexes. To demonstrate the method independency of the convergence testing method, we applied it to three widely used, global SA methods: the screening method known as Morris method or Elementary Effects (Morris 1991, Campolongo et al., 2000), the variance-based Sobol' method (Solbol' 1993, Saltelli et al. 2010) and a derivative-based method known as Parameter Importance index (Goehler et al. 2013). The new convergence testing method is first scrutinized using 12 analytical benchmark functions (Cuntz & Mai et al. 2015) where the true indexes of aforementioned three methods are known. This proof of principle shows that the method reliably determines the uncertainty of the SA results when different budgets are used for the SA. Subsequently, we focus on the model-independency by testing the frugal method using the hydrologic model mHM (www.ufz.de/mhm) with about 50 model parameters. The results show that the new frugal method is able to test the convergence and therefore the reliability of SA results in an efficient way. The appealing feature of this new technique is the necessity of no further model evaluation and therefore enables checking of already processed (and published) sensitivity results. This is one step towards reliable and transferable, published sensitivity results.

Intelligent Condition Diagnosis Method Based on Adaptive Statistic Test Filter and Diagnostic Bayesian Network

PubMed Central

Li, Ke; Zhang, Qiuju; Wang, Kun; Chen, Peng; Wang, Huaqing

2016-01-01

A new fault diagnosis method for rotating machinery based on adaptive statistic test filter (ASTF) and Diagnostic Bayesian Network (DBN) is presented in this paper. ASTF is proposed to obtain weak fault features under background noise, ASTF is based on statistic hypothesis testing in the frequency domain to evaluate similarity between reference signal (noise signal) and original signal, and remove the component of high similarity. The optimal level of significance α is obtained using particle swarm optimization (PSO). To evaluate the performance of the ASTF, evaluation factor Ipq is also defined. In addition, a simulation experiment is designed to verify the effectiveness and robustness of ASTF. A sensitive evaluation method using principal component analysis (PCA) is proposed to evaluate the sensitiveness of symptom parameters (SPs) for condition diagnosis. By this way, the good SPs that have high sensitiveness for condition diagnosis can be selected. A three-layer DBN is developed to identify condition of rotation machinery based on the Bayesian Belief Network (BBN) theory. Condition diagnosis experiment for rolling element bearings demonstrates the effectiveness of the proposed method. PMID:26761006

Intelligent Condition Diagnosis Method Based on Adaptive Statistic Test Filter and Diagnostic Bayesian Network.

PubMed

Li, Ke; Zhang, Qiuju; Wang, Kun; Chen, Peng; Wang, Huaqing

2016-01-08

A new fault diagnosis method for rotating machinery based on adaptive statistic test filter (ASTF) and Diagnostic Bayesian Network (DBN) is presented in this paper. ASTF is proposed to obtain weak fault features under background noise, ASTF is based on statistic hypothesis testing in the frequency domain to evaluate similarity between reference signal (noise signal) and original signal, and remove the component of high similarity. The optimal level of significance α is obtained using particle swarm optimization (PSO). To evaluate the performance of the ASTF, evaluation factor Ipq is also defined. In addition, a simulation experiment is designed to verify the effectiveness and robustness of ASTF. A sensitive evaluation method using principal component analysis (PCA) is proposed to evaluate the sensitiveness of symptom parameters (SPs) for condition diagnosis. By this way, the good SPs that have high sensitiveness for condition diagnosis can be selected. A three-layer DBN is developed to identify condition of rotation machinery based on the Bayesian Belief Network (BBN) theory. Condition diagnosis experiment for rolling element bearings demonstrates the effectiveness of the proposed method.

Detection of lead(II) ions with a DNAzyme and isothermal strand displacement signal amplification.

PubMed

Li, Wenying; Yang, Yue; Chen, Jian; Zhang, Qingfeng; Wang, Yan; Wang, Fangyuan; Yu, Cong

2014-03-15

A DNAzyme based method for the sensitive and selective quantification of lead(II) ions has been developed. A DNAzyme that requires Pb(2+) for activation was selected. An RNA containing DNA substrate was cleaved by the DNAzyme in the presence of Pb(2+). The 2',3'-cyclic phosphate of the cleaved 5'-part of the substrate was efficiently removed by Exonuclease III. The remaining part of the single stranded DNA (9 or 13 base long) was subsequently used as the primer for the strand displacement amplification reaction (SDAR). The method is highly sensitive, 200 pM lead(II) could be easily detected. A number of interference ions were tested, and the sensor showed good selectivity. Underground water samples were also tested, which demonstrated the feasibility of the current approach for real sample applications. It is feasible that our method could be used for DNAzyme or aptazyme based new sensing method developments for the quantification of other target analytes with high sensitivity and selectivity. © 2013 Elsevier B.V. All rights reserved.

Analysis of glycosaminoglycan-derived disaccharides by capillary electrophoresis using laser-induced fluorescence detection

PubMed Central

Chang, Yuqing; Yang, Bo; Zhao, Xue; Linhardt, Robert J.

2012-01-01

A quantitative and highly sensitive method for the analysis of glycosaminoglycan (GAG)-derived disaccharides is presented that relies on capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection. This method enables complete separation of seventeen GAG-derived disaccharides in a single run. Unsaturated disaccharides were derivatized with 2-aminoacridone (AMAC) to improve sensitivity. The limit of detection was at the attomole level and about 100-fold more sensitive than traditional CE-ultraviolet detection. A CE separation timetable was developed to achieve complete resolution and shorten analysis time. The RSD of migration time and peak areas at both low and high concentrations of unsaturated disaccharides are all less than 2.7% and 3.2%, respectively, demonstrating that this is a reproducible method. This analysis was successfully applied to cultured Chinese hamster ovary cell samples for determination of GAG disaccharides. The current method simplifies GAG extraction steps, and reduces inaccuracy in calculating ratios of heparin/heparan sulfate to chondroitin sulfate/dermatan sulfate, resulting from the separate analyses of a single sample. PMID:22609076

Separation and quantification of monothiols and phytochelatins from a wide variety of cell cultures and tissues of trees and other plants using high performance liquid chromatography

Treesearch

Rakesh Minocha; P. Thangavel; Om Parkash Dhankher; Stephanie Long

2008-01-01

The HPLC method presented here for the quantification of metal-binding thiols is considerably shorter than most previously published methods. It is a sensitive and highly reproducible method that separates monobromobimane tagged monothiols (cysteine, glutathione, γ-glutamylcysteine) along with polythiols (PC2, PC3...

Portable evanescent wave fiber biosensor for highly sensitive detection of Shigella

NASA Astrophysics Data System (ADS)

Xiao, Rui; Rong, Zhen; Long, Feng; Liu, Qiqi

2014-11-01

A portable evanescent wave fiber biosensor was developed to achieve the rapid and highly sensitive detection of Shigella. In this study, a DNA probe was covalently immobilized onto fiber-optic biosensors that can hybridize with a fluorescently labeled complementary DNA. The sensitivity of detection for synthesized oligonucleotides can reach 10-10 M. The surface of the sensor can be regenerated with 0.5% sodium dodecyl sulfate solution (pH 1.9) for over 30 times without significant deterioration of performance. The total analysis time for a single sample, including the time for measurement and surface regeneration, was less than 6 min. We employed real-time polymerase chain reaction (PCR) and compared the results of both methods to investigate the actual Shigella DNA detection capability of the fiber-optic biosensor. The fiber-optic biosensor could detect as low as 102 colony-forming unit/mL Shigella. This finding was comparable with that by real-time PCR, which suggests that this method is a potential alternative to existing detection methods.

Sonicated Diagnostic Immunoblot for Bartonellosis

PubMed Central

Mallqui, Vania; Speelmon, Emily C.; Verástegui, Manuela; Maguiña-Vargas, Ciro; Pinell-Salles, Paula; Lavarello, Rosa; Delgado, Jose; Kosek, Margaret; Romero, Sofia; Arana, Yanina; Gilman, Robert H.

2000-01-01

Two simple Bartonella bacilliformis immunoblot preparation methods were developed. Antigen was prepared by two different methods: sonication of whole organisms or glycine extraction. Both methods were then tested for sensitivity and specificity. Well-defined control sera were utilized in the development of these diagnostic immunoblots, and possible cross-reactions were thoroughly examined. Sera investigated for cross-reaction with these diagnostic antigens were drawn from patients with brucellosis, chlamydiosis, Q fever, and cat scratch disease, all of whom were from regions where bartonellosis is not endemic. While both immunoblots yielded reasonable sensitivity and high specificity, we recommend the use of the sonicated immunoblot, which has a higher sensitivity when used to detect acute disease and produces fewer cross-reactions. The sonicated immunoblot reported here is 94% sensitive to chronic bartonellosis and 70% sensitive to acute bartonellosis. In a healthy group, it is 100% specific. This immunoblot preparation requires a simple sonication protocol for the harvesting of B. bacilliformis antigens and is well suited for use in regions of endemicity. PMID:10618267

Systematic review: Comparison of Xpert MTB/RIF, LAMP and SAT methods for the diagnosis of pulmonary tuberculosis.

PubMed

Yan, Liping; Xiao, Heping; Zhang, Qing

2016-01-01

Technological advances in nucleic acid amplification have led to breakthroughs in the early detection of PTB compared to traditional sputum smear tests. The sensitivity and specificity of loop-mediated isothermal amplification (LAMP), simultaneous amplification testing (SAT), and Xpert MTB/RIF for the diagnosis of pulmonary tuberculosis were evaluated. A critical review of previous studies of LAMP, SAT, and Xpert MTB/RIF for the diagnosis of pulmonary tuberculosis that used laboratory culturing as the reference method was carried out together with a meta-analysis. In 25 previous studies, the pooled sensitivity and specificity of the diagnosis of tuberculosis were 93% and 94% for LAMP, 96% and 88% for SAT, and 89% and 98% for Xpert MTB/RIF. The I(2) values for the pooled data were >80%, indicating significant heterogeneity. In the smear-positive subgroup analysis of LAMP, the sensitivity increased from 93% to 98% (I(2) = 2.6%), and specificity was 68% (I(2) = 38.4%). In the HIV-infected subgroup analysis of Xpert MTB/RIF, the pooled sensitivity and specificity were 79% (I(2) = 72.9%) and 99% (I(2) = 64.4%). In the HIV-negative subgroup analysis for Xpert MTB/RIF, the pooled sensitivity and specificity were 72% (I(2) = 49.6%) and 99% (I(2) = 64.5%). LAMP, SAT and Xpert MTB/RIF had comparably high levels of sensitivity and specificity for the diagnosis of tuberculosis. The diagnostic sensitivity and specificity of three methods were similar, with LAMP being highly sensitive for the diagnosis of smear-positive PTB. The cost effectiveness of LAMP and SAT make them particularly suitable tests for diagnosing PTB in developing countries. Copyright © 2015 Elsevier Ltd. All rights reserved.

An Efficient Variable Screening Method for Effective Surrogate Models for Reliability-Based Design Optimization

DTIC Science & Technology

2014-04-01

surrogate model generation is difficult for high -dimensional problems, due to the curse of dimensionality. Variable screening methods have been...a variable screening model was developed for the quasi-molecular treatment of ion-atom collision [16]. In engineering, a confidence interval of...for high -level radioactive waste [18]. Moreover, the design sensitivity method can be extended to the variable screening method because vital

An efficient spectrofluorimetric method adopts doxazosin, terazosin and alfuzosin coupling with orthophthalaldehyde: Application in human plasma

NASA Astrophysics Data System (ADS)

Omar, Mahmoud A.; Mohamed, Abdel-Maaboud I.; Derayea, Sayed M.; Hammad, Mohamed A.; Mohamed, Abobakr A.

2018-04-01

A new, selective and sensitive spectrofluorimetric method was designed for the quantitation of doxazosin (DOX), terazosin (TER) and alfuzosin (ALF) in their dosage forms and human plasma. The method adopts efficient derivatization of the studied drugs with ortho-phthalaldehyde (OPA), in the presence of 2-mercaptoethanol in borate buffer (pH 9.7) to generate a highly fluorescent isoindole derivatives, which can strongly enhance the fluorescence intensities of the studied drugs, allowing their sensitive determination at 430 nm after excitation at 337 nm. The fluorescence-concentration plots were rectilinear over the ranges (10.0-400.0) ng/mL. Detection and quantification limits were found to be (0.52-3.88) and (1.59-11.76) ng/mL, respectively. The proposed method was validated according to ICH guidelines, and successfully applied for the determination of pharmaceutical preparations of the studied drugs. Moreover, the high sensitivity of the proposed method permits its successful application to the analysis of the studied drugs in spiked human plasma with % recovery (96.12 ± 1.34-100.66 ± 0.57, n = 3). A proposal for the reaction mechanism was presented.

Highly sensitive and quantitative detection of rare pathogens through agarose droplet microfluidic emulsion PCR at the single-cell level.

PubMed

Zhu, Zhi; Zhang, Wenhua; Leng, Xuefei; Zhang, Mingxia; Guan, Zhichao; Lu, Jiangquan; Yang, Chaoyong James

2012-10-21

Genetic alternations can serve as highly specific biomarkers to distinguish fatal bacteria or cancer cells from their normal counterparts. However, these mutations normally exist in very rare amount in the presence of a large excess of non-mutated analogs. Taking the notorious pathogen E. coli O157:H7 as the target analyte, we have developed an agarose droplet-based microfluidic ePCR method for highly sensitive, specific and quantitative detection of rare pathogens in the high background of normal bacteria. Massively parallel singleplex and multiplex PCR at the single-cell level in agarose droplets have been successfully established. Moreover, we challenged the system with rare pathogen detection and realized the sensitive and quantitative analysis of a single E. coli O157:H7 cell in the high background of 100,000 excess normal K12 cells. For the first time, we demonstrated rare pathogen detection through agarose droplet microfluidic ePCR. Such a multiplex single-cell agarose droplet amplification method enables ultra-high throughput and multi-parameter genetic analysis of large population of cells at the single-cell level to uncover the stochastic variations in biological systems.

A method for measuring coherent elastic neutrino-nucleus scattering at a far off-axis high-energy neutrino beam target

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

Brice, S. J.; Cooper, R. L.; DeJongh, F.

2014-04-03

We present an experimental method for measuring the process of coherent elastic neutrino-nucleus scattering (CENNS). This method uses a detector situated transverse to a high-energy neutrino beam production target. This detector would be sensitive to the low-energy neutrinos arising from decay-at-rest pions in the target. We discuss the physics motivation for making this measurement and outline the predicted backgrounds and sensitivities using this approach. We report a measurement of neutron backgrounds as found in an off-axis surface location of the Fermilab Booster Neutrino Beam (BNB) target. The results indicate that the Fermilab BNB target is a favorable location for amore » CENNS experiment.« less

Development and validation of a high-performance liquid chromatography method for the quantification of talazoparib in rat plasma: Application to plasma protein binding studies.

PubMed

Hidau, Mahendra Kumar; Kolluru, Srikanth; Palakurthi, Srinath

2018-02-01

A sensitive and selective RP-HPLC method has been developed and validated for the quantification of a highly potent poly ADP ribose polymerase inhibitor talazoparib (TZP) in rat plasma. Chromatographic separation was performed with isocratic elution method. Absorbance for TZP was measured with a UV detector (SPD-20A UV-vis) at a λ max of 227 nm. Protein precipitation was used to extract the drug from plasma samples using methanol-acetonitrile (65:35) as the precipitating solvent. The method proved to be sensitive and reproducible over a 100-2000 ng/mL linearity range with a lower limit of quantification (LLQC) of 100 ng/mL. TZP recovery was found to be >85%. Following analytical method development and validation, it was successfully employed to determine the plasma protein binding of TZP. TZP has a high level of protein binding in rat plasma (95.76 ± 0.38%) as determined by dialysis method. Copyright © 2017 John Wiley & Sons, Ltd.

Quantitative real-time in vivo detection of magnetic nanoparticles by their nonlinear magnetization

NASA Astrophysics Data System (ADS)

Nikitin, M. P.; Torno, M.; Chen, H.; Rosengart, A.; Nikitin, P. I.

2008-04-01

A novel method of highly sensitive quantitative detection of magnetic nanoparticles (MP) in biological tissues and blood system has been realized and tested in real time in vivo experiments. The detection method is based on nonlinear magnetic properties of MP and the related device can record a very small relative variation of nonlinear magnetic susceptibility up to 10-8 at room temperature, providing sensitivity of several nanograms of MP in 0.1ml volume. Real-time quantitative in vivo measurements of dynamics of MP concentration in blood flow have been performed. A catheter that carried the blood flow of a rat passed through the measuring device. After an MP injection, the quantity of MP in the circulating blood was continuously recorded. The method has also been used to evaluate the MP distribution between rat's organs. Its sensitivity was compared with detection of the radioactive MP based on isotope of Fe59. The comparison of magnetic and radioactive signals in the rat's blood and organ samples demonstrated similar sensitivity for both methods. However, the proposed magnetic method is much more convenient as it is safe, less expensive, and provides real-time measurements in vivo. Moreover, the sensitivity of the method can be further improved by optimization of the device geometry.

Multiplexed transcriptome analysis to detect ALK, ROS1 and RET rearrangements in lung cancer

PubMed Central

Rogers, Toni-Maree; Arnau, Gisela Mir; Ryland, Georgina L.; Huang, Stephen; Lira, Maruja E.; Emmanuel, Yvette; Perez, Omar D.; Irwin, Darryl; Fellowes, Andrew P.; Wong, Stephen Q.; Fox, Stephen B.

2017-01-01

ALK, ROS1 and RET gene fusions are important predictive biomarkers for tyrosine kinase inhibitors in lung cancer. Currently, the gold standard method for gene fusion detection is Fluorescence In Situ Hybridization (FISH) and while highly sensitive and specific, it is also labour intensive, subjective in analysis, and unable to screen a large numbers of gene fusions. Recent developments in high-throughput transcriptome-based methods may provide a suitable alternative to FISH as they are compatible with multiplexing and diagnostic workflows. However, the concordance between these different methods compared with FISH has not been evaluated. In this study we compared the results from three transcriptome-based platforms (Nanostring Elements, Agena LungFusion panel and ThermoFisher NGS fusion panel) to those obtained from ALK, ROS1 and RET FISH on 51 clinical specimens. Overall agreement of results ranged from 86–96% depending on the platform used. While all platforms were highly sensitive, both the Agena panel and Thermo Fisher NGS fusion panel reported minor fusions that were not detectable by FISH. Our proof–of–principle study illustrates that transcriptome-based analyses are sensitive and robust methods for detecting actionable gene fusions in lung cancer and could provide a robust alternative to FISH testing in the diagnostic setting. PMID:28181564

Development of a simple and sensitive liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS) method for the determination of cannabidiol (CBD), Δ9-tetrahydrocannabinol (THC) and its metabolites in rat whole blood after oral administration of a single high dose of CBD.

PubMed

Palazzoli, Federica; Citti, Cinzia; Licata, Manuela; Vilella, Antonietta; Manca, Letizia; Zoli, Michele; Vandelli, Maria Angela; Forni, Flavio; Cannazza, Giuseppe

2018-02-20

The investigation of the possible conversion of cannabidiol (CBD) into Δ 9 -tetrahydrocannabinol (THC) in vivo after oral administration of CBD is reported herein since recent publications suggested a rapid conversion in simulated gastric fluid. To this end, single high dose of CBD (50mg/kg) was administered orally to rats and their blood was collected after 3 and 6h. A highly sensitive and selective LC-MS/MS method was developed and fully validated in compliance with the Scientific Working Group of Forensic Toxicology (SWGTOX) standard practices for method validation in forensic toxicology. This method also involved the optimization of cannabinoids and their metabolites extraction in order to remove co-eluting phospholipids and increase the sensitivity of the MS detection. Neither THC nor its metabolites were detected in rat whole blood after 3 or 6h from CBD administration. After oral administration, the amount of CBD dissolved in olive oil was higher than that absorbed from an ethanolic solution. This could be explained by the protection of lipid excipients towards CBD from acidic gastric juice. Copyright © 2017 Elsevier B.V. All rights reserved.

A new real-time method for investigation of affinity properties and binding kinetics of magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Orlov, Alexey V.; Nikitin, Maxim P.; Bragina, Vera A.; Znoyko, Sergey L.; Zaikina, Marina N.; Ksenevich, Tatiana I.; Gorshkov, Boris G.; Nikitin, Petr I.

2015-04-01

A method for quantitative investigation of affinity constants of receptors immobilized on magnetic nanoparticles (MP) is developed based on spectral correlation interferometry (SCI). The SCI records with a picometer resolution the thickness changes of a layer of molecules or nanoparticles due to a biochemical reaction on a cover slip, averaged over the sensing area. The method is compatible with other types of sensing surfaces employed in biosensing. The measured values of kinetic association constants of magnetic nanoparticles are 4 orders of magnitude higher than those of molecular antibody association with antigen. The developed method also suggests highly sensitive detection of antigens in a wide dynamic range. The limit of detection of 92 pg/ml has been demonstrated for prostate-specific antigen (PSA) with 50-nm MP employed as labels, which produce 3-order amplification of the SCI signals. The calibration curve features high sensitivity (slope) of 3-fold signal raise per 10-fold increase of PSA concentration within 4-order dynamic range, which is an attractive compromise for precise quantitative and highly sensitive immunoassay. The proposed biosensing technique offers inexpensive disposable sensor chips of cover slips and represents an economically sound alternative to traditional immunoassays for disease diagnostics, detection of pathogens in food and environmental monitoring.

Chromatographic-ICPMS methods for trace element and isotope analysis of water and biogenic calcite

NASA Astrophysics Data System (ADS)

Klinkhammer, G. P.; Haley, B. A.; McManus, J.; Palmer, M. R.

2003-04-01

ICP-MS is a powerful technique because of its sensitivity and speed of analysis. This is especially true for refractory elements that are notoriously difficult using TIMS and less energetic techniques. However, as ICP-MS instruments become more sensitive to elements of interest they also become more sensitive to interference. This becomes a pressing issue when analyzing samples with high total dissolved solids. This paper describes two trace element methods that overcome these problems by using chromatographic techniques to precondition samples prior to analysis by ICP-MS: separation of rare earth elements (REEs) from seawater using HPLC-ICPMS, and flow-through dissolution of foraminiferal calcite. Using HPLC in combination with ICP-MS it is possible to isolate the REEs from matrix, other transition elements, and each other. This method has been developed for small volume samples (5ml) making it possible to analyze sediment pore waters. As another example, subjecting foram shells to flow-through reagent addition followed by time-resolved analysis in the ICP-MS allows for systematic cleaning and dissolution of foram shells. This method provides information about the relationship between dissolution tendency and elemental composition. Flow-through is also amenable to automation thus yielding the high sample throughput required for paleoceanography, and produces a highly resolved elemental matrix that can be statistically analyzed.

Simultaneous determination of triamcinolone hexacetonide and triamcinolone acetonide in rabbit plasma using a highly sensitive and selective UPLC-MS/MS method.

PubMed

Sun, Wei; Ho, Stacy; Fang, Xiaojun Rick; O'Shea, Thomas; Liu, Hanlan

2018-05-10

An ultra-high pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was successfully developed and qualified for the simultaneous determination of triamcinolone hexacetonide (TAH) and triamcinolone acetonide (TAA, the active metabolite of TAH) in rabbit plasma. To prevent the hydrolysis of TAH to TAA ex vivo during sample collection and processing, we evaluated the effectiveness of several esterase inhibitors to stabilize TAH in plasma. Phenylmethanesulfonyl fluoride (PMSF) at 2.0 mM was chosen to stabilize TAH in rabbit plasma. The developed method is highly sensitive with a lower limit of quantitation of 10.0 pg/mL for both TAA and TAH using a 300 μL plasma aliquot. The method demonstrated good linearity, accuracy, precision, sensitivity, selectivity, recovery, matrix effects, dilution integrity, carryover, and stability. Linearity was obtained over the range of 10-2500 pg/mL. Both intra- and inter-run coefficients of variation were less than 9.1% and accuracies across the assay range were all within 100 ± 8.4%. The run time is under 5 minutes. The method was successfully implemented to support a rabbit pharmacokinetic study of TAH and TAA following a single intra-articular administration of TAH (Aristospan ® ). Copyright © 2018 Elsevier B.V. All rights reserved.

Establishment and Application of a Loop-Mediated Isothermal Amplification Method for Simple, Specific, Sensitive and Rapid Detection of Toxoplasma gondii

PubMed Central

CAO, Lili; CHENG, Ronghua; YAO, Lin; YUAN, Shuxian; YAO, Xinhua

2013-01-01

ABSTRACT The Loop-mediated isothermal amplification (LAMP) method amplifies DNA with high simply, specificity, sensitivity and rapidity. In this study, A LAMP assay with 6 primers targeting a highly conserved region of the GRA1 gene was developed to diagnose Toxoplasma gondii. The reaction time of the LAMP assay was shortened to 30 min after optimizing the reaction system. The LAMP assay was found to be highly specific and stable. The detection limit of the LAMP assay was 10 copies, the same as that of the conventional PCR. We used the LAMP assay to develop a real-time fluorogenic protocol to quantitate T. gondii DNA and generated a log-linear regression plot by plotting the time-to-threshold values against genomic equivalent copies. Furthermore, the LAMP assay was applied to detect T. gondii DNA in 423 blood samples and 380 lymph node samples from 10 pig farms, and positive results were obtained for 7.8% and 8.2% of samples, respectively. The results showed that the LAMP method is slightly more sensitive than conventional PCR (6.1% and 7.6%). Positive samples obtained from 6 pig farms. The LAMP assay established in this study resulted in simple, specific, sensitive and rapid detection of T. gondii DNA and is expected to play an important role in clinical detection of T. gondii. PMID:23965849

High-throughput determination of vancomycin in human plasma by a cost-effective system of two-dimensional liquid chromatography.

PubMed

Sheng, Yanghao; Zhou, Boting

2017-05-26

Therapeutic drug monitoring (TDM) is one of the most important services of clinical laboratories. Two main techniques are commonly used: the immunoassay and chromatography method. We have developed a cost-effective system of two-dimensional liquid chromatography with ultraviolet detection (2D-LC-UV) for high-throughput determination of vancomycin in human plasma that combines the automation and low start-up costs of the immunoassay with the high selectivity and sensitivity of the liquid chromatography coupled with mass spectrometric detection without incurring their disadvantages, achieving high cost-effectiveness. This 2D-LC system offers a large volume injection to provide sufficient sensitivity and uses simulated gradient peak compression technology to control peak broadening and to improve peak shape. A middle column was added to reduce the analysis cycle time and make it suitable for high-throughput routine clinical assays. The analysis cycle time was 4min and the peak width was 0.8min. Compared with other chromatographic methods that have been developed, the analysis cycle time and peak width for vancomycin was reduced significantly. The lower limit of quantification was 0.20μg/mL for vancomycin, which is the same as certain LC-MS/MS methods that have been recently developed and validated. The method is rapid, automated, and low-cost and has high selectivity and sensitivity for the quantification of vancomycin in human plasma, thus making it well-suited for use in hospital clinical laboratories. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct Printing of Stretchable Elastomers for Highly Sensitive Capillary Pressure Sensors.

PubMed

Liu, Wenguang; Yan, Chaoyi

2018-03-28

We demonstrate the successful fabrication of highly sensitive capillary pressure sensors using an innovative 3D printing method. Unlike conventional capacitive pressure sensors where the capacitance changes were due to the pressure-induced interspace variations between the parallel plate electrodes, in our capillary sensors the capacitance was determined by the extrusion and extraction of liquid medium and consequent changes of dielectric constants. Significant pressure sensitivity advances up to 547.9 KPa -1 were achieved. Moreover, we suggest that our innovative capillary pressure sensors can adopt a wide range of liquid mediums, such as ethanol, deionized water, and their mixtures. The devices also showed stable performances upon repeated pressing cycles. The direct and versatile printing method combined with the significant performance advances are expected to find important applications in future stretchable and wearable electronics.

Ab initio structure determination of nanocrystals of organic pharmaceutical compounds by electron diffraction at room temperature using a Timepix quantum area direct electron detector.

PubMed

van Genderen, E; Clabbers, M T B; Das, P P; Stewart, A; Nederlof, I; Barentsen, K C; Portillo, Q; Pannu, N S; Nicolopoulos, S; Gruene, T; Abrahams, J P

2016-03-01

Until recently, structure determination by transmission electron microscopy of beam-sensitive three-dimensional nanocrystals required electron diffraction tomography data collection at liquid-nitrogen temperature, in order to reduce radiation damage. Here it is shown that the novel Timepix detector combines a high dynamic range with a very high signal-to-noise ratio and single-electron sensitivity, enabling ab initio phasing of beam-sensitive organic compounds. Low-dose electron diffraction data (∼ 0.013 e(-) Å(-2) s(-1)) were collected at room temperature with the rotation method. It was ascertained that the data were of sufficient quality for structure solution using direct methods using software developed for X-ray crystallography (XDS, SHELX) and for electron crystallography (ADT3D/PETS, SIR2014).

Improving the performance of a pyramid wavefront sensor with modal sensitivity compensation.

PubMed

Korkiakoski, Visa; Vérinaud, Christophe; Le Louarn, Miska

2008-01-01

We describe a solution to increase the performance of a pyramid wavefront sensor (P-WFS) under bad seeing conditions. We show that most of the issues involve a reduced sensitivity that depends on the magnitude of the high frequency atmospheric distortions. We demonstrate in end-to-end closed loop adaptive optics simulations that with a modal sensitivity compensation method a high-order system with a nonmodulated P-WFS is robust in conditions with the Fried parameter r 0 at 0.5 microm in the range of 0.05-0.10 m. We also show that the method makes it possible to use a modal predictive control system to reach a total performance improvement of 0.06-0.45 in Strehl ratio at 1.6 microm. Especially at r 0=0.05 m the gain is dramatic.

Evaluating the High Risk Groups for Suicide: A Comparison of Logistic Regression, Support Vector Machine, Decision Tree and Artificial Neural Network

PubMed Central

AMINI, Payam; AHMADINIA, Hasan; POOROLAJAL, Jalal; MOQADDASI AMIRI, Mohammad

2016-01-01

Background: We aimed to assess the high-risk group for suicide using different classification methods includinglogistic regression (LR), decision tree (DT), artificial neural network (ANN), and support vector machine (SVM). Methods: We used the dataset of a study conducted to predict risk factors of completed suicide in Hamadan Province, the west of Iran, in 2010. To evaluate the high-risk groups for suicide, LR, SVM, DT and ANN were performed. The applied methods were compared using sensitivity, specificity, positive predicted value, negative predicted value, accuracy and the area under curve. Cochran-Q test was implied to check differences in proportion among methods. To assess the association between the observed and predicted values, Ø coefficient, contingency coefficient, and Kendall tau-b were calculated. Results: Gender, age, and job were the most important risk factors for fatal suicide attempts in common for four methods. SVM method showed the highest accuracy 0.68 and 0.67 for training and testing sample, respectively. However, this method resulted in the highest specificity (0.67 for training and 0.68 for testing sample) and the highest sensitivity for training sample (0.85), but the lowest sensitivity for the testing sample (0.53). Cochran-Q test resulted in differences between proportions in different methods (P<0.001). The association of SVM predictions and observed values, Ø coefficient, contingency coefficient, and Kendall tau-b were 0.239, 0.232 and 0.239, respectively. Conclusion: SVM had the best performance to classify fatal suicide attempts comparing to DT, LR and ANN. PMID:27957463

Aptamer-mediated colorimetric method for rapid and sensitive detection of chloramphenicol in food.

PubMed

Yan, Chao; Zhang, Jing; Yao, Li; Xue, Feng; Lu, Jianfeng; Li, Baoguang; Chen, Wei

2018-09-15

We report an aptamer-mediated colorimetric method for sensitive detection of chloramphenicol (CAP). The aptamer of CAP is immobilized by the hybridization with pre-immobilized capture probe in the microtiter plate. The horseradish peroxidase (HRP) is covalently attached to the aptamer by the biotin-streptavidin system for signal production. CAP will preferably bind with aptamer due to the high binding affinity, which attributes to the release of aptamer and HRP and thus, affects the optical signal intensity. Quantitative determination of CAP is successfully achieved in the wide range from 0.001 to 1000 ng/mL with detection limit of 0.0031 ng/mL, which is more sensitive than traditional immunoassays. This method is further validated by measuring the recovery of CAP spiked in two different food matrices (honey and fish). The aptamer-mediated colorimetric method can be a useful protocol for rapid and sensitive screening of CAP, and may be used as an alternative means for traditional immunoassays. Copyright © 2018 Elsevier Ltd. All rights reserved.

Manufacturing error sensitivity analysis and optimal design method of cable-network antenna structures

NASA Astrophysics Data System (ADS)

Zong, Yali; Hu, Naigang; Duan, Baoyan; Yang, Guigeng; Cao, Hongjun; Xu, Wanye

2016-03-01

Inevitable manufacturing errors and inconsistency between assumed and actual boundary conditions can affect the shape precision and cable tensions of a cable-network antenna, and even result in failure of the structure in service. In this paper, an analytical sensitivity analysis method of the shape precision and cable tensions with respect to the parameters carrying uncertainty was studied. Based on the sensitivity analysis, an optimal design procedure was proposed to alleviate the effects of the parameters that carry uncertainty. The validity of the calculated sensitivities is examined by those computed by a finite difference method. Comparison with a traditional design method shows that the presented design procedure can remarkably reduce the influence of the uncertainties on the antenna performance. Moreover, the results suggest that especially slender front net cables, thick tension ties, relatively slender boundary cables and high tension level can improve the ability of cable-network antenna structures to resist the effects of the uncertainties on the antenna performance.

Rapid and sensitive detection of human astrovirus in water samples by loop-mediated isothermal amplification with hydroxynaphthol blue dye.

PubMed

Yang, Bo-Yun; Liu, Xiao-Lu; Wei, Yu-Mei; Wang, Jing-Qi; He, Xiao-Qing; Jin, Yi; Wang, Zi-Jian

2014-02-14

The aim of this paper was to develop a reverse transcription loop-mediated isothermal amplification (RT-LAMP) method for rapid, sensitive and inexpensive detection of astrovirus. The detection limit of LAMP using in vitro RNA transcripts was 3.6 × 10 copies·μL⁻¹, which is as sensitive as the presently used PCR assays. However, the LAMP products could be identified as different colors with the naked eye following staining with hydroxynaphthol blue dye (HNB). No cross-reactivity with other gastroenteric viruses (rotavirus and norovirus) was observed, indicating the relatively high specificity of LAMP. The RT-LAMP method with HNB was used to effectively detect astrovirus in reclaimed water samples. The LAMP technique described in this study is a cheap, sensitive, specific and rapid method for the detection of astrovirus. The RT-LAMP method can be simply applied for the specific detection of astrovirus and has the potential to be utilized in the field as a screening test.

Highly sensitive determination of iron (III) ion based on phenanthroline probe: Surface-enhanced Raman spectroscopy methods

NASA Astrophysics Data System (ADS)

Chen, Lei; Ma, Ning; Park, Yeonju; Jin, Sila; Hwang, Hoon; Jiang, Dayu; Jung, Young Mee

2018-05-01

In this paper, we introduced Raman spectroscopy techniques that were based on the traditional Fe3 + determination method with phenanthroline as a probe. Interestingly, surface-enhanced Raman spectroscopy (SERS)-based approach exhibited excellent sensitivities to phenanthroline. Different detection mechanisms were observed for the RR and SERS techniques, in which the RR intensity increased with increasing Fe3 + concentration due to the observation of the RR effect of the phenanthroline-Fe2 + complex, whereas the SERS intensity increased with decreasing Fe3 + concentration due to the observation of the SERS effect of the uncomplexed phenanthroline. More importantly, the determination sensitivity was substantially improved in the presence of a SERS-active substrate, giving a detection limit as low as 0.001 μg/mL, which is 20 times lower than the limit of the UV-vis and RR methods. Furthermore, the proposed SERS method was free from other ions interference and can be used quality and sensitivity for the determination of the city tap water.

A novel, colorimetric method for biogenic amine detection based on arylalkylamine N-acetyltransferase.

PubMed

Leng, Pei-Qiang; Zhao, Feng-Lan; Yin, Bin-Cheng; Ye, Bang-Ce

2015-05-21

We developed a novel colorimetric method for rapid detection of biogenic amines based on arylalkylamine N-acetyltransferase (aaNAT). The proposed method offers distinct advantages including simple handling, high speed, low cost, good sensitivity and selectivity.

Highly sensitive surface-scanning detector for the direct bacterial detection using magnetoelastic (ME) biosensors

NASA Astrophysics Data System (ADS)

Liu, Yuzhe; Horikawa, Shin; Chen, I.-Hsuan; Du, Songtao; Wikle, Howard C.; Suh, Sang-Jin; Chin, Bryan A.

2017-05-01

This paper demonstrates a highly sensitive surface-scanning detector used for magnetoelastic (ME) biosensors for the detection of Salmonella on the surface of a polyethylene (PE) food preparation surface. The design and fabrication methods of the new planar spiral coil are introduced. Different concentrations of Salmonella were measured on the surface of a PE board. The efficacy of Salmonella capture and detection is discussed.

A novel photonic crystal fiber Mach-Zehnder interferometer for enhancing refractive index measurement sensitivity

NASA Astrophysics Data System (ADS)

Zhao, Yong; Xia, Feng; Hu, Hai-feng; Chen, Mao-qing

2017-11-01

A novel refractive index (RI) sensor based on photonic crystal fiber Mach-Zehnder interferometer (PCF-MZI) was proposed. It was realized by cascading a section of PCF with half-taper collapse regions (HTCRs) between two single mode fibers (SMFs). The relationship between RI sensitivity and interference length of the PCF-MZI was firstly investigated. Both simulation and experimental results showed that RI sensitivity increased with the increase of interference length. Afterwards, influence of HTCR parameters on RI sensitivity was experimentally investigated to further improve the sensitivity. With intensification of arc discharge intensity in HTCR fabrication process, HTCR with larger maximum taper diameter and longer collapsed region length was obtained, which enhanced evanescent field of the PCF-MZI and then generated higher RI sensitivity. Consequently, a high RI sensitivity of 181.96 nm/refractive index unit (RIU) was achieved in the RI range of 1.3333-1.3574. Increasing arc discharge intensity in HTCR fabrication process has the capacity to improve RI sensitivity of PCF-MZI and meanwhile provides higher mechanical strength and longer sensor life compared to the traditional method of tapering the fiber, which improves the RI sensitivity at the cost of reducing mechanical strength of the sensor. This PCF-MZI was characterized by high RI sensitivity, ease of fabrication, high mechanical strength, and robustness.

Comparison of Non-Culture-Based Methods for Detection of Systemic Fungal Infections, with an Emphasis on Invasive Candida Infections

PubMed Central

White, P. Lewis; Archer, Alice E.; Barnes, Rosemary A.

2005-01-01

The accepted limitations associated with classic culture techniques for the diagnosis of invasive fungal infections have lead to the emergence of many non-culture-based methods. With superior sensitivities and quicker turnaround times, non-culture-based methods may aid the diagnosis of invasive fungal infections. In this review of the diagnostic service, we assessed the performances of two antigen detection techniques (enzyme-linked immunosorbent assay [ELISA] and latex agglutination) with a molecular method for the detection of invasive Candida infection and invasive aspergillosis. The specificities for all three assays were high (≥97%), although the Candida PCR method had enhanced sensitivity over both ELISA and latex agglutination with values of 95%, 75%, and 25%, respectively. However, calculating significant sensitivity values for the Aspergillus detection methods was not feasible due to a low number of proven/probable cases. Despite enhanced sensitivity, the PCR method failed to detect nucleic acid in a probable case of invasive Candida infection that was detected by ELISA. In conclusion, both PCR and ELISA techniques should be used in unison to aid the detection of invasive fungal infections. PMID:15872239

A Novel Real-Time PCR Assay of microRNAs Using S-Poly(T), a Specific Oligo(dT) Reverse Transcription Primer with Excellent Sensitivity and Specificity

PubMed Central

Kang, Kang; Zhang, Xiaoying; Liu, Hongtao; Wang, Zhiwei; Zhong, Jiasheng; Huang, Zhenting; Peng, Xiao; Zeng, Yan; Wang, Yuna; Yang, Yi; Luo, Jun; Gou, Deming

2012-01-01

Background MicroRNAs (miRNAs) are small, non-coding RNAs capable of postranscriptionally regulating gene expression. Accurate expression profiling is crucial for understanding the biological roles of miRNAs, and exploring them as biomarkers of diseases. Methodology/Principal Findings A novel, highly sensitive, and reliable miRNA quantification approach,termed S-Poly(T) miRNA assay, is designed. In this assay, miRNAs are subjected to polyadenylation and reverse transcription with a S-Poly(T) primer that contains a universal reverse primer, a universal Taqman probe, an oligo(dT)11 sequence and six miRNA-specific bases. Individual miRNAs are then amplified by a specific forward primer and a universal reverse primer, and the PCR products are detected by a universal Taqman probe. The S-Poly(T) assay showed a minimum of 4-fold increase in sensitivity as compared with the stem-loop or poly(A)-based methods. A remarkable specificity in discriminating among miRNAs with high sequence similarity was also obtained with this approach. Using this method, we profiled miRNAs in human pulmonary arterial smooth muscle cells (HPASMC) and identified 9 differentially expressed miRNAs associated with hypoxia treatment. Due to its outstanding sensitivity, the number of circulating miRNAs from normal human serum was significantly expanded from 368 to 518. Conclusions/Significance With excellent sensitivity, specificity, and high-throughput, the S-Poly(T) method provides a powerful tool for miRNAs quantification and identification of tissue- or disease-specific miRNA biomarkers. PMID:23152780

SERS strategy based on the modified Au nanoparticles for highly sensitive detection of bisphenol A residues in milk.

PubMed

Yang, Libin; Chen, Yongliang; Shen, Yu; Yang, Ming; Li, Xiuling; Han, Xiaoxia; Jiang, Xin; Zhao, Bing

2018-03-01

Bisphenol A (BPA) is a highly toxic chemical, and its residue in milk product is threatening people's health due to its possible leaching from the packagings and cans with BPA coating. In this work, halides modified Au nanoparticles (NPs) as the modification substrates were first designed for rapid and sensitive determination of BPA residue in real milk by SERS method with the assistance of aggregation agents (Zn 2+ ). It can be concluded that Au NPs modification substrate with assistance of the aggregation agent can remarkably improve the detection sensitivity of BPA residue, which can significantly enhance the SERS signal of BPA and achieve the trace-level detection of BPA residue. Under the optimal conditions, the limit of detection of BPA residue can be as low as to 4.3 × 10 -9 mol/L (equal to 0.98 × 10 -3 mg/kg), which is much less than the standard of European Union (0.6mg/kg). And, there is a good linear relationship (R 2 = 0.990) between the intensity of SERS signal and the logarithm of BPA concentration in the range of 1.0 × 10 -8 -1.0 × 10 -3 mol/L. By this method, the recovery of BPA residue ranges from 89.5% to 100.2% with relative standard deviation between 4.6% and 2.7%. The proposed SERS method proves to be reliable, highly sensitive and possesses good reproducibility, which is very promising for sensitive detection of bisphenols residue in foodstuff. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultra-sensitive high performance liquid chromatography-laser-induced fluorescence based proteomics for clinical applications.

PubMed

Patil, Ajeetkumar; Bhat, Sujatha; Pai, Keerthilatha M; Rai, Lavanya; Kartha, V B; Chidangil, Santhosh

2015-09-08

An ultra-sensitive high performance liquid chromatography-laser induced fluorescence (HPLC-LIF) based technique has been developed by our group at Manipal, for screening, early detection, and staging for various cancers, using protein profiling of clinical samples like, body fluids, cellular specimens, and biopsy-tissue. More than 300 protein profiles of different clinical samples (serum, saliva, cellular samples and tissue homogenates) from volunteers (normal, and different pre-malignant/malignant conditions) were recorded using this set-up. The protein profiles were analyzed using principal component analysis (PCA) to achieve objective detection and classification of malignant, premalignant and healthy conditions with high sensitivity and specificity. The HPLC-LIF protein profiling combined with PCA, as a routine method for screening, diagnosis, and staging of cervical cancer and oral cancer, is discussed in this paper. In recent years, proteomics techniques have advanced tremendously in life sciences and medical sciences for the detection and identification of proteins in body fluids, tissue homogenates and cellular samples to understand biochemical mechanisms leading to different diseases. Some of the methods include techniques like high performance liquid chromatography, 2D-gel electrophoresis, MALDI-TOF-MS, SELDI-TOF-MS, CE-MS and LC-MS techniques. We have developed an ultra-sensitive high performance liquid chromatography-laser induced fluorescence (HPLC-LIF) based technique, for screening, early detection, and staging for various cancers, using protein profiling of clinical samples like, body fluids, cellular specimens, and biopsy-tissue. More than 300 protein profiles of different clinical samples (serum, saliva, cellular samples and tissue homogenates) from healthy and volunteers with different malignant conditions were recorded by using this set-up. The protein profile data were analyzed using principal component analysis (PCA) for objective classification and detection of malignant, premalignant and healthy conditions. The method is extremely sensitive to detect proteins with limit of detection of the order of femto-moles. The HPLC-LIF combined with PCA as a potential proteomic method for the diagnosis of oral cancer and cervical cancer has been discussed in this paper. This article is part of a Special Issue entitled: Proteomics in India. Copyright © 2015 Elsevier B.V. All rights reserved.

Methods to Increase the Sensitivity of High Resolution Melting Single Nucleotide Polymorphism Genotyping in Malaria.

PubMed

Daniels, Rachel; Hamilton, Elizabeth J; Durfee, Katelyn; Ndiaye, Daouda; Wirth, Dyann F; Hartl, Daniel L; Volkman, Sarah K

2015-11-10

Despite decades of eradication efforts, malaria remains a global burden. Recent renewed interest in regional elimination and global eradication has been accompanied by increased genomic information about Plasmodium parasite species responsible for malaria, including characteristics of geographical populations as well as variations associated with reduced susceptibility to anti-malarial drugs. One common genetic variation, single-nucleotide polymorphisms (SNPs), offers attractive targets for parasite genotyping. These markers are useful not only for tracking drug resistance markers but also for tracking parasite populations using markers not under drug or other selective pressures. SNP genotyping methods offer the ability to track drug resistance as well as to fingerprint individual parasites for population surveillance, particularly in response to malaria control efforts in regions nearing elimination status. While informative SNPs have been identified that are agnostic to specific genotyping technologies, high-resolution melting (HRM) analysis is particularly suited to field-based studies. Compared to standard fluorescent-probe based methods that require individual SNPs in a single labeled probe and offer at best 10% sensitivity to detect SNPs in samples that contain multiple genomes (polygenomic), HRM offers 2-5% sensitivity. Modifications to HRM, such as blocked probes and asymmetric primer concentrations as well as optimization of amplification annealing temperatures to bias PCR towards amplification of the minor allele, further increase the sensitivity of HRM. While the sensitivity improvement depends on the specific assay, we have increased detection sensitivities to less than 1% of the minor allele. In regions approaching malaria eradication, early detection of emerging or imported drug resistance is essential for prompt response. Similarly, the ability to detect polygenomic infections and differentiate imported parasite types from cryptic local reservoirs can inform control programs. This manuscript describes modifications to high resolution melting technology that further increase its sensitivity to identify polygenomic infections in patient samples.

Highly Sensitive Determination of 2,4,6-Trinitrotoluene and Related Byproducts Using a Diol Functionalized Column for High Performance Liquid Chromatography

PubMed Central

Gumuscu, Burcu; Erdogan, Zeynep; Guler, Mustafa O.; Tekinay, Turgay

2014-01-01

In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95–98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation. PMID:24905826

Highly sensitive determination of 2,4,6-trinitrotoluene and related byproducts using a diol functionalized column for high performance liquid chromatography.

PubMed

Gumuscu, Burcu; Erdogan, Zeynep; Guler, Mustafa O; Tekinay, Turgay

2014-01-01

In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95-98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation.

Automated High-Speed Video Detection of Small-Scale Explosives Testing

NASA Astrophysics Data System (ADS)

Ford, Robert; Guymon, Clint

2013-06-01

Small-scale explosives sensitivity test data is used to evaluate hazards of processing, handling, transportation, and storage of energetic materials. Accurate test data is critical to implementation of engineering and administrative controls for personnel safety and asset protection. Operator mischaracterization of reactions during testing contributes to either excessive or inadequate safety protocols. Use of equipment and associated algorithms to aid the operator in reaction determination can significantly reduce operator error. Safety Management Services, Inc. has developed an algorithm to evaluate high-speed video images of sparks from an ESD (Electrostatic Discharge) machine to automatically determine whether or not a reaction has taken place. The algorithm with the high-speed camera is termed GoDetect (patent pending). An operator assisted version for friction and impact testing has also been developed where software is used to quickly process and store video of sensitivity testing. We have used this method for sensitivity testing with multiple pieces of equipment. We present the fundamentals of GoDetect and compare it to other methods used for reaction detection.

Gold nanoparticle labeling with tyramide signal amplification for highly sensitive detection of alpha fetoprotein in human serum by ICP-MS.

PubMed

Li, Xiaoting; Chen, Beibei; He, Man; Xiao, Guangyang; Hu, Bin

2018-01-01

In this work, we developed an immunoassay based on tyramide signal amplification (TSA) and gold nanoparticles (Au NPs) labeling for highly sensitive detection of alpha fetoprotein (AFP) by inductively coupled plasma mass spectrometry (ICP-MS). AFP was captured by anti-AFP1 coating on the 96-well plate and labeled by anti-AFP2-horseradish peroxidase (HRP), in which the HRP can catalyze the deposition of biotinylated tyramine on the nearby protein. Then the streptavidin (SA)-Au NPs was labeled on the deposited biotinylated tyramine as the intensive signal probe for ICP-MS measurement. Under the optimal experimental conditions, the limit of detection of the developed method for AFP was 1.85pg/mL and the linear range was 0.005-2ng/mL. The relative standard deviation for seven replicate detections of 0.01ng/mL AFP was 5.2%. The proposed method was successfully applied to the detection of AFP in human serum with good recoveries. This strategy is highly sensitive and easy to operate, and can be extended to the sensitive detection of other biomolecules in human serum. Copyright © 2017 Elsevier B.V. All rights reserved.

A highly sensitive monoclonal antibody based biosensor for quantifying 3-5 ring polycyclic aromatic hydrocarbons (PAHs) in aqueous environmental samples.

PubMed

Li, Xin; Kaattari, Stephen L; Vogelbein, Mary A; Vadas, George G; Unger, Michael A

2016-03-01

Immunoassays based on monoclonal antibodies (mAbs) are highly sensitive for the detection of polycyclic aromatic hydrocarbons (PAHs) and can be employed to determine concentrations in near real-time. A sensitive generic mAb against PAHs, named as 2G8, was developed by a three-step screening procedure. It exhibited nearly uniformly high sensitivity against 3-ring to 5-ring unsubstituted PAHs and their common environmental methylated PAHs, with IC 50 values between 1.68-31 μg/L (ppb). 2G8 has been successfully applied on the KinExA Inline Biosensor system for quantifying 3-5 ring PAHs in aqueous environmental samples. PAHs were detected at a concentration as low as 0.2 μg/L. Furthermore, the analyses only required 10 min for each sample. To evaluate the accuracy of the 2G8-based biosensor, the total PAH concentrations in a series of environmental samples analyzed by biosensor and GC-MS were compared. In most cases, the results yielded a good correlation between methods. This indicates that generic antibody 2G8 based biosensor possesses significant promise for a low cost, rapid method for PAH determination in aqueous samples.

Mechanical modulation method for ultrasensitive phase measurements in photonics biosensing.

PubMed

Patskovsky, S; Maisonneuve, M; Meunier, M; Kabashin, A V

2008-12-22

A novel polarimetry methodology for phase-sensitive measurements in single reflection geometry is proposed for applications in optical transduction-based biological sensing. The methodology uses altering step-like chopper-based mechanical phase modulation for orthogonal s- and p- polarizations of light reflected from the sensing interface and the extraction of phase information at different harmonics of the modulation. We show that even under a relatively simple experimental arrangement, the methodology provides the resolution of phase measurements as low as 0.007 deg. We also examine the proposed approach using Total Internal Reflection (TIR) and Surface Plasmon Resonance (SPR) geometries. For TIR geometry, the response appears to be strongly dependent on the prism material with the best values for high refractive index Si. The detection limit for Si-based TIR is estimated as 10(-5) in terms Refractive Index Units (RIU) change. SPR geometry offers much stronger phase response due to a much sharper phase characteristics. With the detection limit of 3.2*10(-7) RIU, the proposed methodology provides one of best sensitivities for phase-sensitive SPR devices. Advantages of the proposed method include high sensitivity, simplicity of experimental setup and noise immunity as a result of a high stability modulation.

Mechanical System Reliability and Cost Integration Using a Sequential Linear Approximation Method

NASA Technical Reports Server (NTRS)

Kowal, Michael T.

1997-01-01

The development of new products is dependent on product designs that incorporate high levels of reliability along with a design that meets predetermined levels of system cost. Additional constraints on the product include explicit and implicit performance requirements. Existing reliability and cost prediction methods result in no direct linkage between variables affecting these two dominant product attributes. A methodology to integrate reliability and cost estimates using a sequential linear approximation method is proposed. The sequential linear approximation method utilizes probability of failure sensitivities determined from probabilistic reliability methods as well a manufacturing cost sensitivities. The application of the sequential linear approximation method to a mechanical system is demonstrated.

Application of flowerlike MgO for highly sensitive determination of lead via matrix-assisted laser desorption/ionization mass spectrometry.

PubMed

Hou, Jian; Chen, Suming; Cao, Changyan; Liu, Huihui; Xiong, Caiqiao; Zhang, Ning; He, Qing; Song, Weiguo; Nie, Zongxiu

2016-08-01

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) is a high-throughput method to achieve fast and accurate identification of lead (Pb) exposure, but is seldom used because of low ionization efficiency and insufficient sensitivity. Nanomaterials applied in MS are a promising technique to overcome the obstacles of MALDI. Flowerlike MgO nanostructures are applied for highly sensitive lead profiling in real samples. They can be used in two ways: (a) MgO is mixed with N-naphthylethylenediamine dihydrochloride (NEDC) as a novel matrix MgO/NEDC; (b) MgO is applied as an absorbent to enrich Pb ions in very dilute solution. The signal intensities of lead by MgO/NEDC were ten times higher than the NEDC matrix. It also shows superior anti-interference ability when analyzing 10 μmol/L Pb ions in the presence of organic substances or interfering metal ions. By applying MgO as adsorbent, the LOD of lead before enrichment is 1 nmol/L. Blood lead test can be achieved using this enrichment process. Besides, MgO can play the role of internal standard to achieve quantitative analysis. Flowerlike MgO nanostructures were applied for highly sensitive lead profiling in real samples. The method is helpful to prevent Pb contamination in a wide range. Further, the combination of MgO with MALDI MS could inspire more nanomaterials being applied in highly sensitive profiling of pollutants. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Variation in sensitivity, absorption and density of the central rod distribution with eccentricity.

PubMed

Tornow, R P; Stilling, R

1998-01-01

To assess the human rod photopigment distribution and sensitivity with high spatial resolution within the central +/-15 degrees and to compare the results of pigment absorption, sensitivity and rod density distribution (number of rods per square degree). Rod photopigment density distribution was measured with imaging densitometry using a modified Rodenstock scanning laser ophthalmoscope. Dark-adapted sensitivity profiles were measured with green stimuli (17' arc diameter, 1 degrees spacing) using a T ubingen manual perimeter. Sensitivity profiles were plotted on a linear scale and rod photopigment optical density distribution profiles were converted to absorption profiles of the rod photopigment layer. Both the absorption profile of the rod photopigment and the linear sensitivity profile for green stimuli show a minimum at the foveal center and increase steeply with eccentricity. The variation with eccentricity corresponds to the rod density distribution. Rod photopigment absorption profiles, retinal sensitivity profiles, and the rod density distribution are linearly related within the central +/-15 degrees. This is in agreement with theoretical considerations. Both methods, imaging retinal densitometry using a scanning laser ophthalmoscope and dark-adapted perimetry with small green stimuli, are useful for assessing the central rod distribution and sensitivity. However, at present, both methods have limitations. Suggestions for improving the reliability of both methods are given.

Analysis of four toxic metals in a single rice seed by matrix solid phase dispersion -inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

He, Xiufen; Chen, Lixia; Chen, Xin; Yu, Huamei; Peng, Lixu; Han, Bingjun

2016-12-01

Toxic metals in rice pose great risks to human health. Metal bioaccumulation in rice grains is a criterion of breeding. Rice breeding requires a sensitive method to determine metal content in single rice grains to assist the variety selection. In the present study, four toxic metals of arsenic (As), cadmium (Cd), chromium (Cr) and lead (Pb) in a single rice grain were determined by a simple and rapid method. The developed method is based on matrix solid phase dispersion using multi-wall carbon nanotubes (MWCNTs) as dispersing agent and analyzed by inductively coupled plasma mass spectrometry. The experimental parameters were systematically investigated. The limits of detection (LOD) were 5.0, 0.6, 10 and 2.1 ng g-1 for As, Cd, Cr, and Pb, respectively, with relative standard deviations (n = 6) of <7.7%, demonstrating the good sensitivity and precision of the method. The results of 30 real world rice samples analyzed by this method agreed well with those obtained by the standard microwave digestion. The amount of sample required was reduced approximately 100 fold in comparison with the microwave digestion. The method has a high application potential for other sample matrices and elements with high sensitivity and sample throughput.

Analysis of four toxic metals in a single rice seed by matrix solid phase dispersion -inductively coupled plasma mass spectrometry.

PubMed

He, Xiufen; Chen, Lixia; Chen, Xin; Yu, Huamei; Peng, Lixu; Han, Bingjun

2016-12-06

Toxic metals in rice pose great risks to human health. Metal bioaccumulation in rice grains is a criterion of breeding. Rice breeding requires a sensitive method to determine metal content in single rice grains to assist the variety selection. In the present study, four toxic metals of arsenic (As), cadmium (Cd), chromium (Cr) and lead (Pb) in a single rice grain were determined by a simple and rapid method. The developed method is based on matrix solid phase dispersion using multi-wall carbon nanotubes (MWCNTs) as dispersing agent and analyzed by inductively coupled plasma mass spectrometry. The experimental parameters were systematically investigated. The limits of detection (LOD) were 5.0, 0.6, 10 and 2.1 ng g -1 for As, Cd, Cr, and Pb, respectively, with relative standard deviations (n = 6) of <7.7%, demonstrating the good sensitivity and precision of the method. The results of 30 real world rice samples analyzed by this method agreed well with those obtained by the standard microwave digestion. The amount of sample required was reduced approximately 100 fold in comparison with the microwave digestion. The method has a high application potential for other sample matrices and elements with high sensitivity and sample throughput.

Technical advances in flow cytometry-based diagnosis and monitoring of paroxysmal nocturnal hemoglobinuria

PubMed Central

Correia, Rodolfo Patussi; Bento, Laiz Cameirão; Bortolucci, Ana Carolina Apelle; Alexandre, Anderson Marega; Vaz, Andressa da Costa; Schimidell, Daniela; Pedro, Eduardo de Carvalho; Perin, Fabricio Simões; Nozawa, Sonia Tsukasa; Mendes, Cláudio Ernesto Albers; Barroso, Rodrigo de Souza; Bacal, Nydia Strachman

2016-01-01

ABSTRACT Objective: To discuss the implementation of technical advances in laboratory diagnosis and monitoring of paroxysmal nocturnal hemoglobinuria for validation of high-sensitivity flow cytometry protocols. Methods: A retrospective study based on analysis of laboratory data from 745 patient samples submitted to flow cytometry for diagnosis and/or monitoring of paroxysmal nocturnal hemoglobinuria. Results: Implementation of technical advances reduced test costs and improved flow cytometry resolution for paroxysmal nocturnal hemoglobinuria clone detection. Conclusion: High-sensitivity flow cytometry allowed more sensitive determination of paroxysmal nocturnal hemoglobinuria clone type and size, particularly in samples with small clones. PMID:27759825

Flexible hemispheric microarrays of highly pressure-sensitive sensors based on breath figure method.

PubMed

Wang, Zhihui; Zhang, Ling; Liu, Jin; Jiang, Hao; Li, Chunzhong

2018-05-30

Recently, flexible pressure sensors featuring high sensitivity, broad sensing range and real-time detection have aroused great attention owing to their crucial role in the development of artificial intelligent devices and healthcare systems. Herein, highly sensitive pressure sensors based on hemisphere-microarray flexible substrates are fabricated via inversely templating honeycomb structures deriving from a facile and static breath figure process. The interlocked and subtle microstructures greatly improve the sensing characteristics and compressibility of the as-prepared pressure sensor, endowing it a sensitivity as high as 196 kPa-1 and a wide pressure sensing range (0-100 kPa), as well as other superior performance, including a lower detection limit of 0.5 Pa, fast response time (<26 ms) and high reversibility (>10 000 cycles). Based on the outstanding sensing performance, the potential capability of our pressure sensor in capturing physiological information and recognizing speech signals has been demonstrated, indicating promising application in wearable and intelligent electronics.

Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa

PubMed Central

Liu, Xiaofei; Ying, Guangyao; Sun, Chaonan; Yang, Meihua; Zhang, Lei; Zhang, Shanshan; Xing, Xiaoyan; Li, Qian; Kong, Weijun

2018-01-01

The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B1, B2, G1, G2 were extracted from samples by using methanol/water (70:30, v/v) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity (R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15–0.65 and 0.53–2.18 μg/kg, respectively), precision (RSD <11%), stability (RSD of 0.2–3.6%), and accuracy (recovery rates of 86.0–102.3%), which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B1 (AFB1) at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc. PMID:29681848

Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa.

PubMed

Liu, Xiaofei; Ying, Guangyao; Sun, Chaonan; Yang, Meihua; Zhang, Lei; Zhang, Shanshan; Xing, Xiaoyan; Li, Qian; Kong, Weijun

2018-01-01

The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B 1 , B 2 , G 1 , G 2 were extracted from samples by using methanol/water (70:30, v/v ) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity ( R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15-0.65 and 0.53-2.18 μg/kg, respectively), precision (RSD <11%), stability (RSD of 0.2-3.6%), and accuracy (recovery rates of 86.0-102.3%), which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B 1 (AFB 1 ) at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc.

Triplex DNA formation-mediated strand displacement reaction for highly sensitive fluorescent detection of melamine.

PubMed

Liu, Xiaojuan; Xu, Ningning; Gai, Panpan; Li, Feng

2018-08-01

Since melamine is a strong hazard to human health, the development of new methods for highly sensitive detection of melamine is highly desirable. Herein, a novel fluorescent biosensing strategy was designed for sensitive and selective melamine assay based on the recognition ability of abasic (AP) site in triplex towards melamine and signal amplification by Mg 2+ -dependent DNAzyme. In this strategy, the melamine-induced formation of triplex DNA was employed to trigger the strand displacement reaction (SDR). The SDR process converted the specific target recognition into the release and activation of Mg 2+ -dependent DNAzyme, which could catalyze the cleavage of fluorophore/quencher labeled DNA substrate (FQ), resulting in a significantly increased fluorescent signal. Under the optimal conditions, the fluorescent signal has a linear relationship with the logarithm of the melamine concentration in a wide range of 0.005-50 μM. The detection limit was estimated to be 0.9 nM (0.1ppb), which is sufficiently sensitive for practical application. Furthermore, this strategy exhibits high selectivity against other potential interfering substances, and the practical application of this strategy for milk samples reveals that the proposed strategy works well for melamine assay in real samples. Therefore, this strategy presents a new method for the sensitive melamine assay and holds great promise for sensing applications in the environment and the food safety field. Copyright © 2018 Elsevier B.V. All rights reserved.

High-performance liquid chromatographic determination of the beta2-selective adrenergic agonist fenoterol in human plasma after fluorescence derivatization.

PubMed

Kramer, S; Blaschke, G

2001-02-10

A sensitive high-performance liquid chromatographic method has been developed for the determination of the beta2-selective adrenergic agonist fenoterol in human plasma. To improve the sensitivity of the method, fenoterol was derivatized with N-(chloroformyl)-carbazole prior to HPLC analysis yielding highly fluorescent derivatives. The assay involves protein precipitation with acetonitrile, liquid-liquid-extraction of fenoterol from plasma with isobutanol under alkaline conditions followed by derivatization with N-(chloroformyl)-carbazole. Reversed-phase liquid chromatographic determination of the fenoterol derivative was performed using a column-switching system consisting of a LiChrospher 100 RP 18 and a LiChrospher RP-Select B column with acetonitrile, methanol and water as mobile phase. The limit of quantitation in human plasma was 376 pg fenoterol/ml. The method was successfully applied for the assay of fenoterol in patient plasma.

High Sensitivity Analysis of Nanoliter Volumes of Volatile and Nonvolatile Compounds using Matrix Assisted Ionization (MAI) Mass Spectrometry

NASA Astrophysics Data System (ADS)

Hoang, Khoa; Pophristic, Milan; Horan, Andrew J.; Johnston, Murray V.; McEwen, Charles N.

2016-10-01

First results are reported using a simple, fast, and reproducible matrix-assisted ionization (MAI) sample introduction method that provides substantial improvements relative to previously published MAI methods. The sensitivity of the new MAI methods, which requires no laser, high voltage, or nebulizing gas, is comparable to those reported for MALDI-TOF and n-ESI. High resolution full acquisition mass spectra having low chemical background are acquired from low nanoliters of solution using only a few femtomoles of analyte. The limit-of-detection for angiotensin II is less than 50 amol on an Orbitrap Exactive mass spectrometer. Analysis of peptides, including a bovine serum albumin digest, and drugs, including drugs in urine without a purification step, are reported using a 1 μL zero dead volume syringe in which only the analyte solution wetting the walls of the syringe needle is used in the analysis.

Consumption of a diet low in advanced glycation end products for 4 weeks improves insulin sensitivity in overweight women.

PubMed

Mark, Alicja Budek; Poulsen, Malene Wibe; Andersen, Stine; Andersen, Jeanette Marker; Bak, Monika Judyta; Ritz, Christian; Holst, Jens Juul; Nielsen, John; de Courten, Barbora; Dragsted, Lars Ove; Bügel, Susanne Gjedsted

2014-01-01

OBJECTIVE High-heat cooking of food induces the formation of advanced glycation end products (AGEs), which are thought to impair glucose metabolism in type 2 diabetic patients. High intake of fructose might additionally affect endogenous formation of AGEs. This parallel intervention study investigated whether the addition of fructose or cooking methods influencing the AGE content of food affect insulin sensitivity in overweight individuals. RESEARCH DESIGN AND METHODS Seventy-four overweight women were randomized to follow either a high- or low-AGE diet for 4 weeks, together with consumption of either fructose or glucose drinks. Glucose and insulin concentrations-after fasting and 2 h after an oral glucose tolerance test-were measured before and after the intervention. Homeostasis model assessment of insulin resistance (HOMA-IR) and insulin sensitivity index were calculated. Dietary and urinary AGE concentrations were measured (liquid chromatography tandem mass spectrometry) to estimate AGE intake and excretion. RESULTS When adjusted for changes in anthropometric measures during the intervention, the low-AGE diet decreased urinary AGEs, fasting insulin concentrations, and HOMA-IR, compared with the high-AGE diet. Addition of fructose did not affect any outcomes. CONCLUSIONS Diets with high AGE content may increase the development of insulin resistance. AGEs can be reduced by modulation of cooking methods but is unaffected by moderate fructose intake.

Investigation of low-loss spectra and near-edge fine structure of polymers by PEELS

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

Heckmann, W.

Transmission electron microscopy has changed from a purely imaging method to an analytical method. This has been facilitated particularly by equipping electron microscopes with energy filters and with parallel electron energy loss spectrometers (PEELS). Because of their relatively high energy resolution (1 to 2 eV) they provide information not only on the elements present but also on the type of bonds between the molecular groups. Polymers are radiation sensitive and the molecular bonds change as the spectrum is being recorded. This can be observed with PEEL spectrometers that are able to record spectra with high sensitivity and in rapid succession.

Colorimetric and fluorescent detection of hydrazine with high sensitivity and excellent selectivity

NASA Astrophysics Data System (ADS)

Shi, Bingjie; Qi, Sujie; Yu, Mingming; Liu, Chunxia; Li, Zhanxian; Wei, Liuhe; Ni, Zhonghai

2018-01-01

It is critical to develop probes for rapid, selective, and sensitive detection of the highly toxic hydrazine in both environmental and biological science. In this work, under mild condition, a novel colorimetric and off-on fluorescent probe was synthesized for rapid recognition of hydrazine with excellent selectivity over other various species including some biological species, metal ions and anions. The limit of quantification (LOQ) value was 1.5 × 10- 4 M-3.2 × 10- 3 M (colorimetric method) and 1.5 × 10- 4 M - 3.2 × 10- 3 M (fluorescent method) with as low as detection limit of 46.2 μM.

Highly sensitive and selective liquid crystal optical sensor for detection of ammonia.

PubMed

Niu, Xiaofang; Zhong, Yuanbo; Chen, Rui; Wang, Fei; Luo, Dan

2017-06-12

Ammonia detection technologies are very important in environment monitoring. However, most existing technologies are complex and expensive, which limit the useful range of real-time application. Here, we propose a highly sensitive and selective optical sensor for detection of ammonia (NH 3 ) based on liquid crystals (LCs). This optical sensor is realized through the competitive binding between ammonia and liquid crystals on chitosan-Cu 2+ that decorated on glass substrate. We achieve a broad detection range of ammonia from 50 ppm to 1250 ppm, with a low detection limit of 16.6 ppm. This sensor is low-cost, simple, fast, and highly sensitive and selective for detection of ammonia. The proposal LC sensing method can be a sensitive detection platform for other molecule monitors such as proteins, DNAs and other heavy metal ions by modifying sensing molecules.

High-sensitivity stress sensor based on Bragg grating in BDK-doped photosensitive polymer optical fiber

NASA Astrophysics Data System (ADS)

Wang, Tongxin; Luo, Yanhua; Peng, Gang-Ding; Zhang, Qijin

2012-02-01

Bragg grating in a single-mode photosensitive polymer optical fiber (POF) with benzil dimethyl ketal (BDK)-doped in core has been inscribed through the Sagnac ring interference method. The Bragg wavelength of grating is about 1570nm. The stress and strain response of fiber Bragg grating (FBG) has been studied respectively. By fitting the experimental result, the strain sensitivity of FBG in POF has been found to be almost same to that of conventional silica fiber Bragg gratings. However, the stress sensitivity of FBG in POF is measured to be 421pm/MPa, which is 28 times higher than FBG in silica fiber. And such high stress sensitivity makes Bragg grating in a single-mode BDK-doped POF appear to be very attractive for constructing stress sensor with high resolution.

Quantum dots as optical labels for ultrasensitive detection of polyphenols.

PubMed

Akshath, Uchangi Satyaprasad; Shubha, Likitha R; Bhatt, Praveena; Thakur, Munna Singh

2014-07-15

Considering the fact that polyphenols have versatile activity in-vivo, its detection and quantification is very much important for a healthy diet. Laccase enzyme can convert polyphenols to yield mono/polyquinones which can quench Quantum dots fluorescence. This phenomenon of charge transfer from quinones to QDs was exploited as optical labels to detect polyphenols. CdTe QD may undergo dipolar interaction with quinones as a result of broad spectral absorption due to multiple excitonic states resulting from quantum confinement effects. Thus, "turn-off" fluorescence method was applied for ultrasensitive detection of polyphenols by using laccase. We observed proportionate quenching of QDs fluorescence with respect to polyphenol concentration in the range of 100 µg to 1 ng/mL. Also, quenching of the photoluminescence was highly efficient and stable and could detect individual and total polyphenols with high sensitivity (LOD-1 ng/mL). Moreover, proposed method was highly efficient than any other reported methods in terms of sensitivity, specificity and selectivity. Therefore, a novel optical sensor was developed for the detection of polyphenols at a sensitive level based on the charge transfer mechanism. Copyright © 2014 Elsevier B.V. All rights reserved.

COMPARISON OF IN VIVO AND IN VITRO CHEMICAL SCREENING ASSAYS FOR ESTROGEN-RESPONSIVE PROTEIN BIOMARKER EXPRESSION IN THE SHEEPSHEAD MINNOW (CYPRINODON VARIEGATUS)

EPA Science Inventory

Animal welfare concerns and the high cost associated with in vivo chemical screening methods have prompted efforts to develop highly specific and sensitive in vitro techniques to evaluate chemicals for endocrine activity. Diagnostic biomarkers developed using in vitro methods sho...

Highly sensitive screening method for nitroaromatic, nitramine and nitrate ester explosives by high performance liquid chromatography-atmospheric pressure ionization-mass spectrometry (HPLC-API-MS) in forensic applications.

PubMed

Xu, Xiaoma; van de Craats, Anick M; de Bruyn, Peter C A M

2004-11-01

A highly sensitive screening method based on high performance liquid chromatography atmospheric pressure ionization mass spectrometry (HPLC-API-MS) has been developed for the analysis of 21 nitroaromatic, nitramine and nitrate ester explosives, which include the explosives most commonly encountered in forensic science. Two atmospheric pressure ionization (API) methods, atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI), and various experimental conditions have been applied to allow for the detection of all 21 explosive compounds. The limit of detection (LOD) in the full-scan mode has been found to be 0.012-1.2 ng on column for the screening of most explosives investigated. For nitrobenzene, an LOD of 10 ng was found with the APCI method in the negative mode. Although the detection of nitrobenzene, 2-, 3-, and 4-nitrotoluene is hindered by the difficult ionization of these compounds, we have found that by forming an adduct with glycine, LOD values in the range of 3-16 ng on column can be achieved. Compared with previous screening methods with thermospray ionization, the API method has distinct advantages, including simplicity and stability of the method applied, an extended screening range and a low detection limit for the explosives studied.

Pain Sensitivity Subgroups in Individuals With Spine Pain: Potential Relevance to Short-Term Clinical Outcome

PubMed Central

Bialosky, Joel E.; Robinson, Michael E.

2014-01-01

Background Cluster analysis can be used to identify individuals similar in profile based on response to multiple pain sensitivity measures. There are limited investigations into how empirically derived pain sensitivity subgroups influence clinical outcomes for individuals with spine pain. Objective The purposes of this study were: (1) to investigate empirically derived subgroups based on pressure and thermal pain sensitivity in individuals with spine pain and (2) to examine subgroup influence on 2-week clinical pain intensity and disability outcomes. Design A secondary analysis of data from 2 randomized trials was conducted. Methods Baseline and 2-week outcome data from 157 participants with low back pain (n=110) and neck pain (n=47) were examined. Participants completed demographic, psychological, and clinical information and were assessed using pain sensitivity protocols, including pressure (suprathreshold pressure pain) and thermal pain sensitivity (thermal heat threshold and tolerance, suprathreshold heat pain, temporal summation). A hierarchical agglomerative cluster analysis was used to create subgroups based on pain sensitivity responses. Differences in data for baseline variables, clinical pain intensity, and disability were examined. Results Three pain sensitivity cluster groups were derived: low pain sensitivity, high thermal static sensitivity, and high pressure and thermal dynamic sensitivity. There were differences in the proportion of individuals meeting a 30% change in pain intensity, where fewer individuals within the high pressure and thermal dynamic sensitivity group (adjusted odds ratio=0.3; 95% confidence interval=0.1, 0.8) achieved successful outcomes. Limitations Only 2-week outcomes are reported. Conclusions Distinct pain sensitivity cluster groups for individuals with spine pain were identified, with the high pressure and thermal dynamic sensitivity group showing worse clinical outcome for pain intensity. Future studies should aim to confirm these findings. PMID:24764070

Determining water sensitive card spread factors for real world tank mixes

USDA-ARS?s Scientific Manuscript database

The use of water sensitive cards provides a quick and easy method to sample the coverage and deposition from spray applications. Typically, this measure is limited to percent coverage as measures of droplet size, and thus deposition rate, are highly influenced by the stain diameter resulting from t...

Ferritin-Triggered Redox Cycling for Highly Sensitive Electrochemical Immunosensing of Protein.

PubMed

Akanda, Md Rajibul; Ju, Huangxian

2018-06-04

Electrochemical immunoassay amplified with redox cycling has become a challenging topic in highly sensitive analysis of biomarkers. Here a ferritin-triggered redox cycling is reported by using a highly outersphere reaction-philic (OSR-philic) redox mediator ruthenium hexamine (Ru(NH3)63+) to perform the OSR-philic/innersphere reaction-philic (ISR-philic) controlled signal amplification. The screened mediator can meet the needs of lower E0 than ferritin, low reactivity with ISR-philic species, and quick electron exchange with ferritin redox couple. The ferritin-labeled antibody is firstly bounded to immunosensor surface by recognizing the target antigen capured by the immobilized primary antibody. The ferritin then mediates OSR-philic/ISR-philic transfer from Ru(NH3)63+/2+/immunosensor to ferritin-H2O2 redox system. The fast mediation and excellent resistant of highly OSR-philic Ru(NH3)63+ against radical oxygen species lead to highly sensitive electrochemical readout and high signal-to-background ratio. The proposed redox cycling greatly enhances the readout signal and the sensitivity of traditional ferritin-labelled sandwich immunoassay. Using Enteropathogenic Coli (E. Coli) antigen as a model analyte, the developed method shows excellent linearity over the concentration range from 10.0 pg/mL to 0.1 µg/mL and a detection limit of 10.0 fg/mL. The acceptable accuracy, good reproducibility and selectivity of the proposed immunoassay method in real samples indicate the superior practicability of the ferritin-triggered redox cycling.

High-resolution melting analysis for bird sexing: a successful approach to molecular sex identification using different biological samples.

PubMed

Morinha, Francisco; Travassos, Paulo; Seixas, Fernanda; Santos, Nuno; Sargo, Roberto; Sousa, Luís; Magalhães, Paula; Cabral, João A; Bastos, Estela

2013-05-01

High-resolution melting (HRM) analysis is a very attractive and flexible advanced post-PCR method with high sensitivity/specificity for simple, fast and cost-effective genotyping based on the detection of specific melting profiles of PCR products. Next generation real-time PCR systems, along with improved saturating DNA-binding dyes, enable the direct acquisition of HRM data after quantitative PCR. Melting behaviour is particularly influenced by the length, nucleotide sequence and GC content of the amplicons. This method is expanding rapidly in several research areas such as human genetics, reproductive biology, microbiology and ecology/conservation of wild populations. Here we have developed a successful HRM protocol for avian sex identification based on the amplification of sex-specific CHD1 fragments. The melting curve patterns allowed efficient sexual differentiation of 111 samples analysed (plucked feathers, muscle tissues, blood and oral cavity epithelial cells) of 14 bird species. In addition, we sequenced the amplified regions of the CHD1 gene and demonstrated the usefulness of this strategy for the genotype discrimination of various amplicons (CHD1Z and CHD1W), which have small size differences, ranging from 2 bp to 44 bp. The established methodology clearly revealed the advantages (e.g. closed-tube system, high sensitivity and rapidity) of a simple HRM assay for accurate sex differentiation of the species under study. The requirements, strengths and limitations of the method are addressed to provide a simple guide for its application in the field of molecular sexing of birds. The high sensitivity and resolution relative to previous real-time PCR methods makes HRM analysis an excellent approach for improving advanced molecular methods for bird sexing. © 2013 Blackwell Publishing Ltd.

Advanced Mass Spectrometric Methods for the Rapid and Quantitative Characterization of Proteomes

DOE PAGES

Smith, Richard D.

2002-01-01

Progress is reviewedmore » towards the development of a global strategy that aims to extend the sensitivity, dynamic range, comprehensiveness and throughput of proteomic measurements based upon the use of high performance separations and mass spectrometry. The approach uses high accuracy mass measurements from Fourier transform ion cyclotron resonance mass spectrometry (FTICR) to validate peptide ‘accurate mass tags’ (AMTs) produced by global protein enzymatic digestions for a specific organism, tissue or cell type from ‘potential mass tags’ tentatively identified using conventional tandem mass spectrometry (MS/MS). This provides the basis for subsequent measurements without the need for MS/ MS. High resolution capillary liquid chromatography separations combined with high sensitivity, and high resolution accurate FTICR measurements are shown to be capable of characterizing peptide mixtures of more than 10 5 components. The strategy has been initially demonstrated using the microorganisms Saccharomyces cerevisiae and Deinococcus radiodurans. Advantages of the approach include the high confidence of protein identification, its broad proteome coverage, high sensitivity, and the capability for stableisotope labeling methods for precise relative protein abundance measurements. Abbreviations : LC, liquid chromatography; FTICR, Fourier transform ion cyclotron resonance; AMT, accurate mass tag; PMT, potential mass tag; MMA, mass measurement accuracy; MS, mass spectrometry; MS/MS, tandem mass spectrometry; ppm, parts per million.« less

Measurement of dispersion of nanoparticles in a dense suspension by high-sensitivity low-coherence dynamic light scattering

NASA Astrophysics Data System (ADS)

Ishii, Katsuhiro; Nakamura, Sohichiro; Sato, Yuki

2014-08-01

High-sensitivity low-coherence DLS apply to measurement of particle size distribution of pigments suspended in a ink. This method can be apply to extremely dense and turbid media without dilution. We show the temporal variation of particle size distribution of thixotropy and sedimentary pigments due to aggregation, agglomerate, and sedimentation. Moreover, we demonstrate the influence of dilution of ink to particle size distribution.

Evaluation of microarray data normalization procedures using spike-in experiments

PubMed Central

Rydén, Patrik; Andersson, Henrik; Landfors, Mattias; Näslund, Linda; Hartmanová, Blanka; Noppa, Laila; Sjöstedt, Anders

2006-01-01

Background Recently, a large number of methods for the analysis of microarray data have been proposed but there are few comparisons of their relative performances. By using so-called spike-in experiments, it is possible to characterize the analyzed data and thereby enable comparisons of different analysis methods. Results A spike-in experiment using eight in-house produced arrays was used to evaluate established and novel methods for filtration, background adjustment, scanning, channel adjustment, and censoring. The S-plus package EDMA, a stand-alone tool providing characterization of analyzed cDNA-microarray data obtained from spike-in experiments, was developed and used to evaluate 252 normalization methods. For all analyses, the sensitivities at low false positive rates were observed together with estimates of the overall bias and the standard deviation. In general, there was a trade-off between the ability of the analyses to identify differentially expressed genes (i.e. the analyses' sensitivities) and their ability to provide unbiased estimators of the desired ratios. Virtually all analysis underestimated the magnitude of the regulations; often less than 50% of the true regulations were observed. Moreover, the bias depended on the underlying mRNA-concentration; low concentration resulted in high bias. Many of the analyses had relatively low sensitivities, but analyses that used either the constrained model (i.e. a procedure that combines data from several scans) or partial filtration (a novel method for treating data from so-called not-found spots) had with few exceptions high sensitivities. These methods gave considerable higher sensitivities than some commonly used analysis methods. Conclusion The use of spike-in experiments is a powerful approach for evaluating microarray preprocessing procedures. Analyzed data are characterized by properties of the observed log-ratios and the analysis' ability to detect differentially expressed genes. If bias is not a major problem; we recommend the use of either the CM-procedure or partial filtration. PMID:16774679

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

Liu, Ying

My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were ablemore » to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic resolution, high column stability, and high sensitivity. In addition, this method showed potential usefulness for the sensitive and quick analysis of hydrolysis products of polysaccharides, and for trace level analysis of individual oligosaccharides or oligosaccharide isomers from biological systems.« less

A novel approach to mask defect inspection

NASA Astrophysics Data System (ADS)

Sagiv, Amir; Shirman, Yuri; Mangan, Shmoolik

2008-10-01

Memory chips, now constituting a major part of semiconductor market, posit a special challenge for inspection, as they are generally produced with the smallest half-pitch available with today's technology. This is true, in particular, to photomasks of advanced memory devices, which are at the forefront of the "low-k1" regime. In this paper we present a novel photomask inspection approach, that is particularly suitable for low-k1 layers of advanced memory chips, owing to their typical dense and periodic structure. The method we present can produce a very strong signal for small mask defects, by suppression of the modulation of the pattern's image. Unlike dark-field detection, however, here a single diffraction order associated with the pattern generates a constant "gray" background image, that is used for signal enhancement. We define the theoretical basis for the new detection technique, and show, both analytically and numerically, that it can easily achieve a detection line past the printability spec, and that in cases it is at least as sensitive as high-resolution based detection. We also demonstrate this claim experimentally on a customer mask, using the platform of Applied Material's newly released Aera2TM mask inspection tool. The high sensitivity demonstrates the important and often overlooked concept that resolution is not synonymous with sensitivity. The novel detection method is advantageous in several other aspects, such as the very simple implementation, the high throughput, and the relatively simple pre- and post-processing algorithms required for signal extraction. These features, and in particular the very high sensitivity, make this novel detection method an attractive inspection option for advanced memory devices.

Sensitive and selective determination of methylenedioxylated amphetamines by high-performance liquid chromatography with fluorimetric detection.

PubMed

Sadeghipour, F; Veuthey, J L

1997-11-07

A rapid, sensitive and selective liquid chromatographic method with fluorimetric detection was developed for the separation and quantification of four methylenedioxylated amphetamines without interference of other drugs of abuse and common substances found in illicit tablets. The method was validated by examining linearity, precision and accuracy as well as detection and quantification limits. Methylenedioxylated amphetamines were quantified in eight tablets from illicit drug seizures and results were quantitatively compared to HPLC-UV analyses. To demonstrate the better sensitivity of the fluorimetric detection, methylenedioxylated amphetamines were analyzed in serum after a liquid-liquid extraction procedure and results were also compared to HPLC-UV analyses.

A simple and highly sensitive colorimetric detection method for gaseous formaldehyde.

PubMed

Feng, Liang; Musto, Christopher J; Suslick, Kenneth S

2010-03-31

A colorimetric detection method using amine-functionalized polymer films doped with a pH indicator has been developed for the rapid, sensitive, and quantitative detection of gaseous formaldehyde at concentrations well below the immediately dangerous to life or health (IDLH) limit. In 1 min, visible color changes are easily observed, even down to the permissible exposure limit (PEL) at 750 ppb. The limit of detection is below 50 ppb (7% of the PEL) after 10 min of exposure. This sensor is essentially unaffected by changes in humidity or temperature (4 to 50 degrees C) and is not sensitive to common interferents.

Enzyme immunoassays for IgG and IgM antibodies to Toxoplasma gondii based on enhanced chemiluminescence.

PubMed Central

Crouch, C F

1995-01-01

AIMS--To evaluate the clinical performance of enzyme immunoassays for IgG and IgM antibodies to Toxoplasma gondii based on enhanced chemiluminescence. METHODS--Classification of routine clinical samples from the originating laboratories was compared with that obtained using the chemiluminescence based assays. Resolution of discordant results was achieved by testing in alternative enzyme immunoassays (IgM) or by an independent laboratory using the dye test (IgG). RESULTS--Compared with resolved data, the IgM assay was found to be highly specific (100%) with a cut off selected to give optimal performance with respect to both the early detection of specific IgM and the detection of persistent levels of specific IgM (sensitivity 98%). Compared with resolved data, the IgG assay was shown to have a sensitivity and a specificity of 99.4%. CONCLUSIONS--The Amerlite Toxo IgM assay possesses high levels of sensitivity and specificity. Assay interference due to rheumatoid factor like substances is not a problem. The Amerlite Toxo IgG assay possesses good sensitivity and specificity, but is less sensitive for the detection of seroconversion than methods detecting both IgG and IgM. PMID:7560174

Pi-pi* orbital transitions and photo-degeneracy of C.acuminata sensitized solar cells

NASA Astrophysics Data System (ADS)

Abodunrin, T.; Boyo, A.; Usikalu, M.; Obafemi, L.; Oladapo, O.; Kotsedi, L.; Yenus, Z.; Maaza, M.

2017-04-01

Dye-sensitized solar cells (DSSCs) have acquired great prominence as favourable low-cost photovoltaics due to their ease of fabrication, all- year -availability, ease of obtaining raw materials and adjustable optical properties like transparency and colour. These advantages coupled with the ability to work under poor lighting makes them a suitable candidate for next generation of research. In this research, C.acuminata-sensitized photo anodes play an important role for achieving high performance since the porous metal oxide films provide a large specific surface area for dye loading and the possibility to extend the absorption threshold of past studies of sensitizers. The doctor blade method and high-temperature sintering were some of the methods used in the fabrication of the photo anode. A study of the performance of the C.acuminata-DSSCs with four different electrolyte sensitizers based on iodide redox mediator is determined. The result is DSSCs that exhibit a maximum power output of 39.37 W, fill factor of 0.7 and a power conversion efficiency of 0.6% under unfavourable sunlight intensity conditions and photo-degradation of about 37.5 % in absorbance after 425 suns.

Highly transparent carbon counter electrode prepared via an in situ carbonization method for bifacial dye-sensitized solar cells.

PubMed

Bu, Chenghao; Liu, Yumin; Yu, Zhenhua; You, Sujian; Huang, Niu; Liang, Liangliang; Zhao, Xing-Zhong

2013-08-14

A facile in situ carbonization method was demonstrated to prepare the highly transparent carbon counter electrode (CE) with good mechanical stability for bifacial dye-sensitized solar cells (DSCs). The optical and electrochemical properties of carbon CEs were dramatically affected by the composition and concentration of the precursor. The well-optimized carbon CE exhibited high transparency and sufficient catalytic activity for I3(-) reduction. The bifacial DSC with obtained carbon CE achieved a high power conversion efficiency (PCE) of 5.04% under rear-side illumination, which approaches 85% that of front-side illumination (6.07%). Moreover, the device shows excellent stability as confirmed by the aging test. These promising results reveal the enormous potential of this transparent carbon CE in scaling up and commercialization of low cost and effective bifacial DSCs.

California sea lion (Zalophus californianus) aerial hearing sensitivity measured using auditory steady-state response and psychophysical methods.

PubMed

Mulsow, Jason; Finneran, James J; Houser, Dorian S

2011-04-01

Although electrophysiological methods of measuring the hearing sensitivity of pinnipeds are not yet as refined as those for dolphins and porpoises, they appear to be a promising supplement to traditional psychophysical procedures. In order to further standardize electrophysiological methods with pinnipeds, a within-subject comparison of psychophysical and auditory steady-state response (ASSR) measures of aerial hearing sensitivity was conducted with a 1.5-yr-old California sea lion. The psychophysical audiogram was similar to those previously reported for otariids, with a U-shape, and thresholds near 10 dB re 20 μPa at 8 and 16 kHz. ASSR thresholds measured using both single and multiple simultaneous amplitude-modulated tones closely reproduced the psychophysical audiogram, although the mean ASSR thresholds were elevated relative to psychophysical thresholds. Differences between psychophysical and ASSR thresholds were greatest at the low- and high-frequency ends of the audiogram. Thresholds measured using the multiple ASSR method were not different from those measured using the single ASSR method. The multiple ASSR method was more rapid than the single ASSR method, and allowed for threshold measurements at seven frequencies in less than 20 min. The multiple ASSR method may be especially advantageous for hearing sensitivity measurements with otariid subjects that are untrained for psychophysical procedures.

Self-estimation or phototest measurement of skin UV sensitivity and its association with people's attitudes towards sun exposure.

PubMed

Falk, Magnus

2014-02-01

Fitzpatrick's classification is the most common way of assessing skin UV sensitivity. The study aim was to investigate how self-estimated and actual UV sensitivity, as measured by phototest, are associated with attitudes towards sunbathing and the propensity to increase sun protection, as well as the correlation between self-estimated and actual UV sensitivity. A total of 166 primary healthcare patients filled-out a questionnaire investigating attitudes towards sunbathing and the propensity to increase sun protection. They reported their skin type according to Fitzpatrick, and a UV sensitivity phototest was performed. Self-rated low UV sensitivity (skin type III-VI) was associated with a more positive attitude towards sunbathing and a lower propensity to increase sun protection, compared to high UV sensitivity. The correlation between the two methods was weak. The findings might indicate that individuals with a perceived low but in reality high UV sensitivity do not seek adequate sun protection with regard to skin cancer risk. Furthermore, the poor correlation between self-reported and actual UV sensitivity, measured by phototest, makes the clinical use of Fitzpatrick's classification questionable.

The Design and Optimization of a Highly Sensitive and Overload-Resistant Piezoresistive Pressure Sensor

PubMed Central

Meng, Xiawei; Zhao, Yulong

2016-01-01

A piezoresistive pressure sensor with a beam-membrane-dual-island structure is developed for micro-pressure monitoring in the field of aviation, which requires great sensitivity and overload resistance capacity. The design, fabrication, and test of the sensor are presented in this paper. By analyzing the stress distribution of sensitive elements using the finite element method, a novel structure incorporating sensitive beams with a traditional bossed diaphragm is built up. The proposed structure proved to be advantageous in terms of high sensitivity and high overload resistance compared with the conventional bossed diaphragm and flat diaphragm structures. Curve fittings of surface stress and deflection based on ANSYS simulation results are performed to establish the sensor equations. Fabricated on an n-type single crystal silicon wafer, the sensor chips are wire-bonded to a printed circuit board (PCB) and packaged for experiments. The static and dynamic characteristics are tested and discussed. Experimental results show that the sensor has a sensitivity as high as 17.339 μV/V/Pa in the range of 500 Pa at room temperature, and a high overload resistance of 200 times overpressure. Due to the excellent performance, the sensor can be applied in measuring micro-pressure lower than 500 Pa. PMID:27005627

Solvothermal Synthesis of Hierarchical TiO2 Microstructures with High Crystallinity and Superior Light Scattering for High-Performance Dye-Sensitized Solar Cells.

PubMed

Li, Zhao-Qian; Mo, Li-E; Chen, Wang-Chao; Shi, Xiao-Qiang; Wang, Ning; Hu, Lin-Hua; Hayat, Tasawar; Alsaedi, Ahmed; Dai, Song-Yuan

2017-09-20

In this article, hierarchical TiO 2 microstructures (HM-TiO 2 ) were synthesized by a simple solvothermal method adopting tetra-n-butyl titanate as the titanium source in a mixed solvent composed of N,N-dimethylformamide and acetic acid. Due to the high crystallinity and superior light-scattering ability, the resultant HM-TiO 2 are advantageous as photoanodes for dye-sensitized solar cells. When assembled to the entire photovoltaic device with C101 dye as a sensitizer, the pure HM-TiO 2 -based solar cells showed an ultrahigh photovoltage up to 0.853 V. Finally, by employing the as-obtained HM-TiO 2 as the scattering layer and optimizing the architecture of dye-sensitized solar cells, both higher photovoltage and incident photon-to-electron conversion efficiency value were harvested with respect to TiO 2 nanoparticles-based dye-sensitized solar cells, resulting in a high power conversion efficiency of 9.79%. This work provides a promising strategy to develop photoanode materials with outstanding photoelectric conversion performance.

Radial magnetic resonance imaging (MRI) using a rotating radiofrequency (RF) coil at 9.4 T.

PubMed

Li, Mingyan; Weber, Ewald; Jin, Jin; Hugger, Thimo; Tesiram, Yasvir; Ullmann, Peter; Stark, Simon; Fuentes, Miguel; Junge, Sven; Liu, Feng; Crozier, Stuart

2018-02-01

The rotating radiofrequency coil (RRFC) has been developed recently as an alternative approach to multi-channel phased-array coils. The single-element RRFC avoids inter-channel coupling and allows a larger coil element with better B 1 field penetration when compared with an array counterpart. However, dedicated image reconstruction algorithms require accurate estimation of temporally varying coil sensitivities to remove artefacts caused by coil rotation. Various methods have been developed to estimate unknown sensitivity profiles from a few experimentally measured sensitivity maps, but these methods become problematic when the RRFC is used as a transceiver coil. In this work, a novel and practical radial encoding method is introduced for the RRFC to facilitate image reconstruction without the measurement or estimation of rotation-dependent sensitivity profiles. Theoretical analyses suggest that the rotation-dependent sensitivities of the RRFC can be used to create a uniform profile with careful choice of sampling positions and imaging parameters. To test this new imaging method, dedicated electronics were designed and built to control the RRFC speed and hence positions in synchrony with imaging parameters. High-quality phantom and animal images acquired on a 9.4 T pre-clinical scanner demonstrate the feasibility and potential of this new RRFC method. Copyright © 2017 John Wiley & Sons, Ltd.

Imaging alpha particle detector

DOEpatents

Anderson, David F.

1985-01-01

A method and apparatus for detecting and imaging alpha particles sources is described. A conducting coated high voltage electrode (1) and a tungsten wire grid (2) constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source (3) to be quantitatively or qualitatively analyzed. A thin polyester film window (4) allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

Imaging alpha particle detector

DOEpatents

Anderson, D.F.

1980-10-29

A method and apparatus for detecting and imaging alpha particles sources is described. A dielectric coated high voltage electrode and a tungsten wire grid constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source to be quantitatively or qualitatively analyzed. A thin polyester film window allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

Ab initio structure determination of nanocrystals of organic pharmaceutical compounds by electron diffraction at room temperature using a Timepix quantum area direct electron detector

PubMed Central

van Genderen, E.; Clabbers, M. T. B.; Das, P. P.; Stewart, A.; Nederlof, I.; Barentsen, K. C.; Portillo, Q.; Pannu, N. S.; Nicolopoulos, S.; Gruene, T.; Abrahams, J. P.

2016-01-01

Until recently, structure determination by transmission electron microscopy of beam-sensitive three-dimensional nanocrystals required electron diffraction tomography data collection at liquid-nitrogen temperature, in order to reduce radiation damage. Here it is shown that the novel Timepix detector combines a high dynamic range with a very high signal-to-noise ratio and single-electron sensitivity, enabling ab initio phasing of beam-sensitive organic compounds. Low-dose electron diffraction data (∼0.013 e− Å−2 s−1) were collected at room temperature with the rotation method. It was ascertained that the data were of sufficient quality for structure solution using direct methods using software developed for X-ray crystallography (XDS, SHELX) and for electron crystallography (ADT3D/PETS, SIR2014). PMID:26919375

Measurements of carbon-14 with cavity ring-down spectroscopy

DOE PAGES

McCartt, A. D.; Ognibene, T.; Bench, G.; ...

2015-06-13

Accelerator Mass Spectrometry (AMS) is the most sensitive method for quantitation of 14C in biological samples. This technology has been used in a variety of low dose, human health related studies over the last 20 years when very high sensitivity was needed. AMS helped pioneer these scientific methods, but its expensive facilities and requirements for highly trained technical staff have limited their proliferation. Quantification of 14C by cavity ring-down spectroscopy (CRDS) offers an approach that eliminates many of the shortcomings of an accelerator-based system and would supplement the use of AMS in biomedical research. Our initial prototype, using a non-idealmore » wavelength laser and under suboptimal experimental conditions, has a 3.5-modern, 1-σ precision for detection of milligram-sized, carbon-14-elevated samples. Furthermore, these results demonstrate proof of principle and provided a starting point for the development of a spectrometer capable of biologically relevant sensitivities.« less

Electrochemical Glucose Biosensor of Platinum Nanospheres Connected by Carbon Nanotubes

PubMed Central

Claussen, Jonathan C.; Kim, Sungwon S.; Haque, Aeraj ul; Artiles, Mayra S.; Porterfield, D. Marshall; Fisher, Timothy S.

2010-01-01

Background Glucose biosensors comprised of nanomaterials such as carbon nanotubes (CNTs) and metallic nanoparticles offer enhanced electrochemical performance that produces highly sensitive glucose sensing. This article presents a facile biosensor fabrication and biofunctionalization procedure that utilizes CNTs electrochemically decorated with platinum (Pt) nanospheres to sense glucose amperometrically with high sensitivity. Method Carbon nanotubes are grown in situ by microwave plasma chemical vapor deposition (MPCVD) and electro-chemically decorated with Pt nanospheres to form a CNT/Pt nanosphere composite biosensor. Carbon nanotube electrodes are immobilized with fluorescently labeled bovine serum albumin (BSA) and analyzed with fluorescence microscopy to demonstrate their biocompatibility. The enzyme glucose oxidase (GOX) is immobilized onto the CNT/Pt nanosphere biosensor by a simple drop-coat method for amperometric glucose sensing. Results Fluorescence microscopy demonstrates the biofunctionalization capability of the sensor by portraying adsorption of fluorescently labeled BSA unto MPCVD-grown CNT electrodes. The subsequent GOX–CNT/Pt nanosphere biosensor demonstrates a high sensitivity toward H2O2 (7.4 μA/mM/cm2) and glucose (70 μA/mM/cm2), with a glucose detection limit and response time of 380 nM (signal-to-noise ratio = 3) and 8 s (t90%), respectively. The apparent Michaelis–Menten constant (0.64 mM) of the biosensor also reflects the improved sensitivity of the immobilized GOX/nanomaterial complexes. Conclusions The GOX–CNT/Pt nanosphere biosensor outperforms similar CNT, metallic nanoparticle, and more conventional carbon-based biosensors in terms of glucose sensitivity and detection limit. The biosensor fabrication and biofunctionalization scheme can easily be scaled and adapted for microsensors for physiological research applications that require highly sensitive glucose sensing. PMID:20307391

Highly Sensitive Droplet Digital PCR Method for Detection of EGFR-Activating Mutations in Plasma Cell-Free DNA from Patients with Advanced Non-Small Cell Lung Cancer.

PubMed

Zhu, Guanshan; Ye, Xin; Dong, Zhengwei; Lu, Ya Chao; Sun, Yun; Liu, Yi; McCormack, Rose; Gu, Yi; Liu, Xiaoqing

2015-05-01

Epidermal growth factor receptor (EGFR) mutation testing in plasma cell-free DNA from lung cancer patients is an emerging clinical tool. However, compared with tissue testing, the sensitivity of plasma testing is not yet satisfactory because of the highly fragmented nature of plasma cell-free DNA, low fraction of tumor DNA, and limitations of available detection technologies. We therefore developed a highly sensitive and specific droplet digital PCR method for plasma EGFR mutation (exon19 deletions and L858R) testing. Plasma from 86 EGFR-tyrosine kinase inhibitor-naive lung cancer patients was tested and compared with EGFR mutation status of matched tumor tissues tested by amplification refractory mutation system. By using EGFR mutation-positive cell DNA, we optimized the droplet digital PCR assays to reach 0.04% sensitivity. The plasma testing sensitivity and specificity, compared with the matched tumor tissues tested by amplification refractory mutation system, were 81.82% (95% CI, 59.72%-94.81%) and 98.44% (95% CI, 91.60%-99.96%), respectively, for exon19 deletions, with 94.19% concordance rate (κ = 0.840; 95% CI, 0.704-0.976; P < 0.0001), whereas they were 80.00% (95% CI, 51.91%-95.67%) and 95.77% (95% CI, 88.14%-99.12%), respectively, for L858R, with 93.02% concordance rate (κ = 0.758; 95% CI, 0.571-0.945; P < 0.0001). The reported highly sensitive and specific droplet digital PCR assays for EGFR mutation detection have potential in clinical blood testing. Copyright © 2015 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.

Photonic crystal fiber temperature sensor with high sensitivity based on surface plasmon resonance

NASA Astrophysics Data System (ADS)

Wu, Junjun; Li, Shuguang; shi, Min; Feng, Xinxing

2018-07-01

A high sensitivity photonic crystal fiber (PCF) temperature sensor based on surface plasmon resonance is proposed and evaluated using the finite element method. Besides, the coupling phenomenon is studied. The gold layer deposited on the polishing surface of D-shape PCF is used as the metal to stimulate surface plasma, which can improves the sensitivity. Through exquisite design, the birefringence of the fiber is improved, which makes the loss of y-polarization far greater than the loss of x-polarization. The D-shape fiber avoids filling metal and liquid into the air-holes, which can contact with fluid directly to feel temperature. When the phase matching condition is satisfied, the core mode will couple with the surface plasma mode. The resonance position of y-polarization is very sensitive to the temperature change. The simulation shows that the PCF has high sensitivity of 36.86 nm/°C in y-polarization and wide detection that from 10 °C to 85 °C.

Designing novel nano-immunoassays: antibody orientation versus sensitivity

NASA Astrophysics Data System (ADS)

Puertas, S.; Moros, M.; Fernández-Pacheco, R.; Ibarra, M. R.; Grazú, V.; de la Fuente, J. M.

2010-12-01

There is a growing interest in the use of magnetic nanoparticles (MNPs) for their application in quantitative and highly sensitive biosensors. Their use as labels of biological recognition events and their detection by means of some magnetic method constitute a very promising strategy for quantitative high-sensitive lateral-flow assays. In this paper, we report the importance of nanoparticle functionalization for the improvement of sensitivity for a lateral-flow immunoassay. More precisely, we have found that immobilization of IgG anti-hCG through its polysaccharide moieties on MNPs allows more successful recognition of the hCG hormone. Although we have used the detection of hCG as a model in this work, the strategy of binding antibodies to MNPs through its sugar chains reported here is applicable to other antibodies. It has huge potential as it will be very useful for the development of quantitative and high-sensitive lateral-flow assays for its use on human and veterinary, medicine, food and beverage manufacturing, pharmaceutical, medical biologics and personal care product production, environmental remediation, etc.

Highly sensitive Europium doped SrSO4 OSL nanophosphor for radiation dosimetry applications

NASA Astrophysics Data System (ADS)

Patle, Anita; Patil, R. R.; Kulkarni, M. S.; Bhatt, B. C.; Moharil, S. V.

2015-10-01

Highly sensitive Europium doped SrSO4 optically stimulated luminescent (OSL) phosphor was developed by synthesizing a nano phosphor which is treated at 1000 °C. Excellent OSL properties are observed in the developed phosphor and the sensitivity is found to be 1.26 times to that of the commercial Al2O3:C (Landauer Inc.) phosphor based on area integration method. The sample showed a single TL glow peak around 230 °C which is found to reduce by 47% after the OSL readout. Sublinear dose response with the saturation around 100 mGy is observed in this sample which suggests that it is extremely sensitive and hence will be suitable in detecting very low dose levels. Minimum measurable dose on the used set up is estimated to be 1.42 μGy. Practically no fading is observed for first ten days and the phosphor has excellent reusability. High sensitivity, low fading, excellent reusability will make this phosphor suitable for radiation dosimetry applications using OSL.

Eating High Fat Chow Decreases Dopamine Clearance in Adolescent and Adult Male Rats but Selectively Enhances the Locomotor Stimulating Effects of Cocaine in Adolescents

PubMed Central

Baladi, Michelle G.; Horton, Rebecca E.; Owens, William A.; Daws, Lynette C.

2015-01-01

Background: Feeding conditions can influence dopamine neurotransmission and impact behavioral and neurochemical effects of drugs acting on dopamine systems. This study examined whether eating high fat chow alters the locomotor effects of cocaine and dopamine transporter activity in adolescent (postnatal day 25) and adult (postnatal day 75) male Sprague-Dawley rats. Methods: Dose-response curves for cocaine-induced locomotor activity were generated in rats with free access to either standard or high fat chow or restricted access to high fat chow (body weight matched to rats eating standard chow). Results: Compared with eating standard chow, eating high fat chow increased the sensitivity of adolescent, but not adult, rats to the acute effects of cocaine. When tested once per week, sensitization to the locomotor effects of cocaine was enhanced in adolescent rats eating high fat chow compared with adolescent rats eating standard chow. Sensitization to cocaine was not different among feeding conditions in adults. When adolescent rats that previously ate high fat chow ate standard chow, sensitivity to cocaine returned to normal. As measured by chronoamperometry, dopamine clearance rate in striatum was decreased in both adolescent and adult rats eating high fat chow compared with age-matched rats eating standard chow. Conclusions: These results suggest that high fat diet-induced reductions in dopamine clearance rate do not always correspond to increased sensitivity to the locomotor effects of cocaine, suggesting that mechanisms other than dopamine transporter might play a role. Moreover, in adolescent but not adult rats, eating high fat chow increases sensitivity to cocaine and enhances the sensitization that develops to cocaine. PMID:25805560

A semi-automated magnetic capture probe based DNA extraction and real-time PCR method applied in the Swedish surveillance of Echinococcus multilocularis in red fox (Vulpes vulpes) faecal samples.

PubMed

Isaksson, Mats; Hagström, Åsa; Armua-Fernandez, Maria Teresa; Wahlström, Helene; Ågren, Erik Olof; Miller, Andrea; Holmberg, Anders; Lukacs, Morten; Casulli, Adriano; Deplazes, Peter; Juremalm, Mikael

2014-12-19

Following the first finding of Echinococcus multilocularis in Sweden in 2011, 2985 red foxes (Vulpes vulpes) were analysed by the segmental sedimentation and counting technique. This is a labour intensive method and requires handling of the whole carcass of the fox, resulting in a costly analysis. In an effort to reduce the cost of labour and sample handling, an alternative method has been developed. The method is sensitive and partially automated for detection of E. multilocularis in faecal samples. The method has been used in the Swedish E. multilocularis monitoring program for 2012-2013 on more than 2000 faecal samples. We describe a new semi-automated magnetic capture probe DNA extraction method and real time hydrolysis probe polymerase chain reaction assay (MC-PCR) for the detection of E. multilocularis DNA in faecal samples from red fox. The diagnostic sensitivity was determined by validating the new method against the sedimentation and counting technique in fox samples collected in Switzerland where E. multilocularis is highly endemic. Of 177 foxes analysed by the sedimentation and counting technique, E. multilocularis was detected in 93 animals. Eighty-two (88%, 95% C.I 79.8-93.9) of these were positive in the MC-PCR. In foxes with more than 100 worms, the MC-PCR was positive in 44 out of 46 (95.7%) cases. The two MC-PCR negative samples originated from foxes with only immature E. multilocularis worms. In foxes with 100 worms or less, (n = 47), 38 (80.9%) were positive in the MC-PCR. The diagnostic specificity of the MC-PCR was evaluated using fox scats collected within the Swedish screening. Of 2158 samples analysed, two were positive. This implies that the specificity is at least 99.9% (C.I. = 99.7-100). The MC-PCR proved to have a high sensitivity and a very high specificity. The test is partially automated but also possible to perform manually if desired. The test is well suited for nationwide E. multilocularis surveillance programs where sampling of fox scats is done to reduce the costs for sampling and where a test with a high sensitivity and a very high specificity is needed.

Enhanced H2 sensitivity at room temperature of ZnO nanowires functionalized by Pd nanoparticles

NASA Astrophysics Data System (ADS)

Ren, Shoutian; Fan, Guanghua; Qu, Shiliang; Wang, Qiang

2011-10-01

For sensitive detection of H2, ZnO nanowires networks decorated with photo-decomposed Pd nanoparticles were fabricated between femtosecond laser-writing interdigitated electrodes by chemical vapor deposition method. When H2 concentration is increased from 20 to 4000 ppm at room temperature, sensitivity of the sample is increased from 3.7% to 1017.9%. The high sensitivity can be explained by considering the reaction between the adsorbed O2- and the disassociated H atoms facilitated by Pd nanoparticles. This mechanism is further supported by the H2 response results under UV light illumination, which can reduce the amount of O2- on the ZnO surface, leading to depressed sensitivity. The sensor also shows high selectivity, long-term stability, and ultra-low power consumption of nanowatt level, due to the novel fabrication process.

Least Squares Shadowing Sensitivity Analysis of Chaotic Flow Around a Two-Dimensional Airfoil

NASA Technical Reports Server (NTRS)

Blonigan, Patrick J.; Wang, Qiqi; Nielsen, Eric J.; Diskin, Boris

2016-01-01

Gradient-based sensitivity analysis has proven to be an enabling technology for many applications, including design of aerospace vehicles. However, conventional sensitivity analysis methods break down when applied to long-time averages of chaotic systems. This breakdown is a serious limitation because many aerospace applications involve physical phenomena that exhibit chaotic dynamics, most notably high-resolution large-eddy and direct numerical simulations of turbulent aerodynamic flows. A recently proposed methodology, Least Squares Shadowing (LSS), avoids this breakdown and advances the state of the art in sensitivity analysis for chaotic flows. The first application of LSS to a chaotic flow simulated with a large-scale computational fluid dynamics solver is presented. The LSS sensitivity computed for this chaotic flow is verified and shown to be accurate, but the computational cost of the current LSS implementation is high.

Sterilization of endoscopic instruments.

PubMed

Sabnis, Ravindra B; Bhattu, Amit; Vijaykumar, Mohankumar

2014-03-01

Sterilization of endoscopic instruments is an important but often ignored topic. The purpose of this article is to review the current literature on the sterilization of endoscopic instruments and elaborate on the appropriate sterilization practices. Autoclaving is an economic and excellent method of sterilizing the instruments that are not heat sensitive. Heat sensitive instruments may get damaged with hot sterilization methods. Several new endoscopic instruments such as flexible ureteroscopes, chip on tip endoscopes, are added in urologists armamentarium. Many of these instruments are heat sensitive and hence alternative efficacious methods of sterilization are necessary. Although ethylene oxide and hydrogen peroxide are excellent methods of sterilization, they have some drawbacks. Gamma irradiation is mainly for disposable items. Various chemical agents are widely used even though they achieve high-level disinfection rather than sterilization. This article reviews various methods of endoscopic instrument sterilization with their advantages and drawbacks. If appropriate sterilization methods are adopted, then it not only will protect patients from procedure-related infections but prevent hypersensitive allergic reactions. It will also protect instruments from damage and increase its longevity.

Consumers' sensitivity to androstenone and the evaluation of different cooking methods to mask boar taint.

PubMed

Borrisser-Pairó, F; Panella-Riera, N; Gil, M; Kallas, Z; Linares, M B; Egea, M; Garrido, M D; Oliver, M A

2017-01-01

Boar taint is an unpleasant odour and flavour present in some entire male pigs that is due to the presence of androstenone and skatole. The aim of the study was to assess the sensitivity of 150 consumers to androstenone and to compare the acceptability and liking of meat from castrated and entire pigs, cooked with different cooking methods. Meat samples consisted of loins from castrated (CM) and entire male pigs (EM) with high levels of androstenone cooked by two cooking methods: sous-vide and fried/breaded with garlic and parsley. Consumers evaluated smell and flavour acceptability, and overall liking of CM and EM for each cooking method. The results of the study showed that dislike of androstenone odour increased significantly with sensitivity. The results of acceptability and overall liking were similar in CM and EM for both cooking methods. Therefore, the two cooking methods used in the study may be useful to mask boar taint. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modified GMDH-NN algorithm and its application for global sensitivity analysis

NASA Astrophysics Data System (ADS)

Song, Shufang; Wang, Lu

2017-11-01

Global sensitivity analysis (GSA) is a very useful tool to evaluate the influence of input variables in the whole distribution range. Sobol' method is the most commonly used among variance-based methods, which are efficient and popular GSA techniques. High dimensional model representation (HDMR) is a popular way to compute Sobol' indices, however, its drawbacks cannot be ignored. We show that modified GMDH-NN algorithm can calculate coefficients of metamodel efficiently, so this paper aims at combining it with HDMR and proposes GMDH-HDMR method. The new method shows higher precision and faster convergent rate. Several numerical and engineering examples are used to confirm its advantages.

The Efficacy of Vigorous-Intensity Exercise as an Aid to Smoking Cessation in Adults with High Anxiety Sensitivity: A Randomized Controlled Trial

PubMed Central

Smits, Jasper A. J.; Zvolensky, Michael J.; Davis, Michelle L.; Rosenfield, David; Marcus, Bess H.; Church, Timothy S.; Powers, Mark B.; Frierson, Georita M.; Otto, Michael W.; Hopkins, Lindsey B.; Brown, Richard A.; Baird, Scarlett O.

2015-01-01

Objective High anxiety sensitivity predicts poor smoking cessation outcomes. Aerobic exercise reduces anxiety sensitivity and aspects of the risk conferred by anxiety sensitivity. In the current study, we examined whether exercise can aid smoking cessation in adults with high anxiety sensitivity. Method Participants were sedentary and low activity adult daily smokers (N = 136) with elevated prescreen anxiety sensitivity. Participants received 15 weeks of standard smoking cessation treatment (ST: cognitive behavioral therapy plus nicotine replacement therapy). Additionally, participants were simultaneously randomized to 15 weeks of either an exercise intervention (ST+EX; n = 72) or a wellness education control condition (ST+CTRL; n = 64). Self-reported smoking abstinence was assessed weekly during the intervention, at the end of treatment (10 weeks following the target quit date), and at 4 and 6 months following the target quit date. Abstinence was verified by expired carbon monoxide readings and saliva cotinine. Results Results indicated that point prevalence abstinence (PPA) and prolonged abstinence (PA) rates were significantly higher for ST+EX than for ST+CTRL at each of the major end points among persons with high anxiety sensitivity (PPA: b=−.91, SE=.393, t(1171)=−2.33, p=.020; PA: b=−.98, SE=.346, t(132)=−2.84, p=.005), but not among those with low anxiety sensitivity (PPA: b=−.23, SE=.218, t(1171)=−1.06, p=..29; PA: b=−.31, SE=.306, t(132)=−1.01, p=.32) Conclusions The present results suggest that exercise faciliates the odds of quit success for smokers with high levels of anxiety sensitivity, and therefore, may be a useful therapeutic tactic for this high-risk segment of the smoking population. PMID:26513517

High Sensitivity Combined with Extended Structural Coverage of Labile Compounds via Nanoelectrospray Ionization at Subambient Pressures

DOE PAGES

Cox, Jonathan T.; Kronewitter, Scott R.; Shukla, Anil K.; ...

2014-09-15

Subambient pressure ionization with nanoelectrospray (SPIN) has proven to be effective in producing ions with high efficiency and transmitting them to low pressures for high sensitivity mass spectrometry (MS) analysis. Here we present evidence that not only does the SPIN source improve MS sensitivity but also allows for gentler ionization conditions. The gentleness of a conventional heated capillary electrospray ionization (ESI) source and the SPIN source was compared by the liquid chromatography mass spectrometry (LC-MS) analysis of colominic acid. Colominic acid is a mixture of sialic acid polymers of different lengths containing labile glycosidic linkages between monomer units necessitating amore » gentle ion source. By coupling the SPIN source with high resolution mass spectrometry and using advanced data processing tools, we demonstrate much extended coverage of sialic acid polymer chains as compared to using the conventional ESI source. Additionally we show that SPIN-LC-MS is effective in elucidating polymer features with high efficiency and high sensitivity previously unattainable by the conventional ESI-LC-MS methods.« less

Analysis of the causes of discrepancies in troponin I concentrations as measured by ARCHITECT High-Sensitive Troponin I ST and STACIA CLEIA cTnI.

PubMed

Kondo, Takashi; Kobayashi, Daisuke; Mochizuki, Maki; Asanuma, Kouichi; Takahashi, Satoshi

2017-01-01

Background Recently developed reagents for the highly sensitive measurement of cardiac troponin I are useful for early diagnosis of acute coronary syndrome. However, differences in measured values between these new reagents and previously used reagents have not been well studied. In this study, we aimed to compare the values between ARCHITECT High-Sensitive Troponin I ST (newly developed reagents), ARCHITECT Troponin I ST and STACIA CLEIA cardiac troponin I (two previously developed reagent kits). Methods Gel filtration high-performance liquid chromatography was used to analyse the causes of differences in measured values. Results The measured values differed between ARCHITECT High-Sensitive Troponin I ST and STACIA CLEIA cardiac troponin I reagents (r = 0.82). Cross-reactivity tests using plasma with added skeletal-muscle troponin I resulted in higher reactivity (2.17-3.03%) for the STACIA CLEIA cardiac troponin I reagents compared with that for the ARCHITECT High-Sensitive Troponin I ST reagents (less than 0.014%). In addition, analysis of three representative samples using gel filtration high-performance liquid chromatography revealed reagent-specific differences in the reactivity against each cardiac troponin I complex; this could explain the differences in values observed for some of the samples. Conclusion The newly developed ARCHITECT High-Sensitive Troponin I ST reagents were not affected by the presence of skeletal-muscle troponin I in the blood and may be useful for routine examinations.

Integrated Droplet-Based Microextraction with ESI-MS for Removal of Matrix Interference in Single-Cell Analysis.

PubMed

Zhang, Xiao-Chao; Wei, Zhen-Wei; Gong, Xiao-Yun; Si, Xing-Yu; Zhao, Yao-Yao; Yang, Cheng-Dui; Zhang, Si-Chun; Zhang, Xin-Rong

2016-04-29

Integrating droplet-based microfluidics with mass spectrometry is essential to high-throughput and multiple analysis of single cells. Nevertheless, matrix effects such as the interference of culture medium and intracellular components influence the sensitivity and the accuracy of results in single-cell analysis. To resolve this problem, we developed a method that integrated droplet-based microextraction with single-cell mass spectrometry. Specific extraction solvent was used to selectively obtain intracellular components of interest and remove interference of other components. Using this method, UDP-Glc-NAc, GSH, GSSG, AMP, ADP and ATP were successfully detected in single MCF-7 cells. We also applied the method to study the change of unicellular metabolites in the biological process of dysfunctional oxidative phosphorylation. The method could not only realize matrix-free, selective and sensitive detection of metabolites in single cells, but also have the capability for reliable and high-throughput single-cell analysis.

Adaptive interference cancel filter for evoked potential using high-order cumulants.

PubMed

Lin, Bor-Shyh; Lin, Bor-Shing; Chong, Fok-Ching; Lai, Feipei

2004-01-01

This paper is to present evoked potential (EP) processing using adaptive interference cancel (AIC) filter with second and high order cumulants. In conventional ensemble averaging method, people have to conduct repetitively experiments to record the required data. Recently, the use of AIC structure with second statistics in processing EP has proved more efficiency than traditional averaging method, but it is sensitive to both of the reference signal statistics and the choice of step size. Thus, we proposed higher order statistics-based AIC method to improve these disadvantages. This study was experimented in somatosensory EP corrupted with EEG. Gradient type algorithm is used in AIC method. Comparisons with AIC filter on second, third, fourth order statistics are also presented in this paper. We observed that AIC filter with third order statistics has better convergent performance for EP processing and is not sensitive to the selection of step size and reference input.

A kinetic method for the determination of thiourea by its catalytic effect in micellar media

NASA Astrophysics Data System (ADS)

Abbasi, Shahryar; Khani, Hossein; Gholivand, Mohammad Bagher; Naghipour, Ali; Farmany, Abbas; Abbasi, Freshteh

2009-03-01

A highly sensitive, selective and simple kinetic method was developed for the determination of trace levels of thiourea based on its catalytic effect on the oxidation of janus green in phosphoric acid media and presence of Triton X-100 surfactant without any separation and pre-concentration steps. The reaction was monitored spectrophotometrically by tracing the formation of the green-colored oxidized product of janus green at 617 nm within 15 min of mixing the reagents. The effect of some factors on the reaction speed was investigated. Following the recommended procedure, thiourea could be determined with linear calibration graph in 0.03-10.00 μg/ml range. The detection limit of the proposed method is 0.02 μg/ml. Most of foreign species do not interfere with the determination. The high sensitivity and selectivity of the proposed method allowed its successful application to fruit juice and industrial waste water.

Impact of normalization methods on high-throughput screening data with high hit rates and drug testing with dose-response data.

PubMed

Mpindi, John-Patrick; Swapnil, Potdar; Dmitrii, Bychkov; Jani, Saarela; Saeed, Khalid; Wennerberg, Krister; Aittokallio, Tero; Östling, Päivi; Kallioniemi, Olli

2015-12-01

Most data analysis tools for high-throughput screening (HTS) seek to uncover interesting hits for further analysis. They typically assume a low hit rate per plate. Hit rates can be dramatically higher in secondary screening, RNAi screening and in drug sensitivity testing using biologically active drugs. In particular, drug sensitivity testing on primary cells is often based on dose-response experiments, which pose a more stringent requirement for data quality and for intra- and inter-plate variation. Here, we compared common plate normalization and noise-reduction methods, including the B-score and the Loess a local polynomial fit method under high hit-rate scenarios of drug sensitivity testing. We generated simulated 384-well plate HTS datasets, each with 71 plates having a range of 20 (5%) to 160 (42%) hits per plate, with controls placed either at the edge of the plates or in a scattered configuration. We identified 20% (77/384) as the critical hit-rate after which the normalizations started to perform poorly. Results from real drug testing experiments supported this estimation. In particular, the B-score resulted in incorrect normalization of high hit-rate plates, leading to poor data quality, which could be attributed to its dependency on the median polish algorithm. We conclude that a combination of a scattered layout of controls per plate and normalization using a polynomial least squares fit method, such as Loess helps to reduce column, row and edge effects in HTS experiments with high hit-rates and is optimal for generating accurate dose-response curves. john.mpindi@helsinki.fi. Supplementary information: R code and Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press.

Adaptation of a visualized loop-mediated isothermal amplification technique for field detection of Plasmodium vivax infection.

PubMed

Tao, Zhi-Yong; Zhou, Hua-Yun; Xia, Hui; Xu, Sui; Zhu, Han-Wu; Culleton, Richard L; Han, Eun-Taek; Lu, Feng; Fang, Qiang; Gu, Ya-Ping; Liu, Yao-Bao; Zhu, Guo-Ding; Wang, Wei-Ming; Li, Ju-Lin; Cao, Jun; Gao, Qi

2011-06-21

Loop-mediated isothermal amplification (LAMP) is a high performance method for detecting DNA and holds promise for use in the molecular detection of infectious pathogens, including Plasmodium spp. However, in most malaria-endemic areas, which are often resource-limited, current LAMP methods are not feasible for diagnosis due to difficulties in accurately interpreting results with problems of sensitive visualization of amplified products, and the risk of contamination resulting from the high quantity of amplified DNA produced. In this study, we establish a novel visualized LAMP method in a closed-tube system, and validate it for the diagnosis of malaria under simulated field conditions. A visualized LAMP method was established by the addition of a microcrystalline wax-dye capsule containing the highly sensitive DNA fluorescence dye SYBR Green I to a normal LAMP reaction prior to the initiation of the reaction. A total of 89 blood samples were collected on filter paper and processed using a simple boiling method for DNA extraction, and then tested by the visualized LAMP method for Plasmodium vivax infection. The wax capsule remained intact during isothermal amplification, and released the DNA dye to the reaction mixture only when the temperature was raised to the melting point following amplification. Soon after cooling down, the solidified wax sealed the reaction mix at the bottom of the tube, thus minimizing the risk of aerosol contamination. Compared to microscopy, the sensitivity and specificity of LAMP were 98.3% (95% confidence interval (CI): 91.1-99.7%) and 100% (95% CI: 88.3-100%), and were in close agreement with a nested polymerase chain reaction method. This novel, cheap and quick visualized LAMP method is feasible for malaria diagnosis in resource-limited field settings.

Multiple shooting shadowing for sensitivity analysis of chaotic dynamical systems

NASA Astrophysics Data System (ADS)

Blonigan, Patrick J.; Wang, Qiqi

2018-02-01

Sensitivity analysis methods are important tools for research and design with simulations. Many important simulations exhibit chaotic dynamics, including scale-resolving turbulent fluid flow simulations. Unfortunately, conventional sensitivity analysis methods are unable to compute useful gradient information for long-time-averaged quantities in chaotic dynamical systems. Sensitivity analysis with least squares shadowing (LSS) can compute useful gradient information for a number of chaotic systems, including simulations of chaotic vortex shedding and homogeneous isotropic turbulence. However, this gradient information comes at a very high computational cost. This paper presents multiple shooting shadowing (MSS), a more computationally efficient shadowing approach than the original LSS approach. Through an analysis of the convergence rate of MSS, it is shown that MSS can have lower memory usage and run time than LSS.

Color sensitive silicon photomultiplers with micro-cell level encoding for DOI PET detectors

NASA Astrophysics Data System (ADS)

Shimazoe, Kenji; Koyama, Akihiro; Takahashi, Hiroyuki; Ganka, Thomas; Iskra, Peter; Marquez Seco, Alicia; Schneider, Florian; Wiest, Florian

2017-11-01

There have been many studies on Depth Of Interaction (DOI) identification for high resolution Positron Emission Tomography (PET) systems, including those on phoswich detectors, double-sided readout, light sharing methods, and wavelength discrimination. The wavelength discrimination method utilizes the difference in wavelength of stacked scintillators and requires a color sensitive photodetector. Here, a new silicon photomultiplier (SiPM) coupled to a color filter (colorSiPM) was designed and fabricated for DOI detection. The fabricated colorSiPM has two anode readouts that are sensitive to blue and green color. The colorSiPM's response and DOI identification capability for stacked GAGG and LYSO crystals are characterized. The fabricated colorSiPM is sensitive enough to detect a peak of 662 keV from a 137 Cs source.

Phase-Sensitive Surface Plasmon Resonance Sensors: Recent Progress and Future Prospects

PubMed Central

Deng, Shijie; Wang, Peng; Yu, Xinglong

2017-01-01

Surface plasmon resonance (SPR) is an optical sensing technique that is capable of performing real-time, label-free and high-sensitivity monitoring of molecular interactions. SPR biosensors can be divided according to their operating principles into angle-, wavelength-, intensity- and phase-interrogated devices. With their complex optical configurations, phase-interrogated SPR sensors generally provide higher sensitivity and throughput, and have thus recently emerged as prominent biosensing devices. To date, several methods have been developed for SPR phase interrogation, including heterodyne detection, polarimetry, shear interferometry, spatial phase modulation interferometry and temporal phase modulation interferometry. This paper summarizes the fundamentals of phase-sensitive SPR sensing, reviews the available methods for phase interrogation of these sensors, and discusses the future prospects for and trends in the development of this technology. PMID:29206182

A high-throughput liquid bead array-based screening technology for Bt presence in GMO manipulation.

PubMed

Fu, Wei; Wang, Huiyu; Wang, Chenguang; Mei, Lin; Lin, Xiangmei; Han, Xueqing; Zhu, Shuifang

2016-03-15

The number of species and planting areas of genetically modified organisms (GMOs) has been rapidly developed during the past ten years. For the purpose of GMO inspection, quarantine and manipulation, we have now devised a high-throughput Bt-based GMOs screening method based on the liquid bead array. This novel method is based on the direct competitive recognition between biotinylated antibodies and beads-coupled antigens, searching for Bt presence in samples if it contains Bt Cry1 Aa, Bt Cry1 Ab, Bt Cry1 Ac, Bt Cry1 Ah, Bt Cry1 B, Bt Cry1 C, Bt Cry1 F, Bt Cry2 A, Bt Cry3 or Bt Cry9 C. Our method has a wide GMO species coverage so that more than 90% of the whole commercialized GMO species can be identified throughout the world. Under our optimization, specificity, sensitivity, repeatability and availability validation, the method shows a high specificity and 10-50 ng/mL sensitivity of quantification. We then assessed more than 1800 samples in the field and food market to prove capacity of our method in performing a high throughput screening work for GMO manipulation. Our method offers an applicant platform for further inspection and research on GMO plants. Copyright © 2015 Elsevier B.V. All rights reserved.

Sensitivity and Specificity of Cardiac Tissue Discrimination Using Fiber-Optics Confocal Microscopy.

PubMed

Huang, Chao; Sachse, Frank B; Hitchcock, Robert W; Kaza, Aditya K

2016-01-01

Disturbances of the cardiac conduction system constitute a major risk after surgical repair of complex cases of congenital heart disease. Intraoperative identification of the conduction system may reduce the incidence of these disturbances. We previously developed an approach to identify cardiac tissue types using fiber-optics confocal microscopy and extracellular fluorophores. Here, we applied this approach to investigate sensitivity and specificity of human and automated classification in discriminating images of atrial working myocardium and specialized tissue of the conduction system. Two-dimensional image sequences from atrial working myocardium and nodal tissue of isolated perfused rodent hearts were acquired using a fiber-optics confocal microscope (Leica FCM1000). We compared two methods for local application of extracellular fluorophores: topical via pipette and with a dye carrier. Eight blinded examiners evaluated 162 randomly selected images of atrial working myocardium (n = 81) and nodal tissue (n = 81). In addition, we evaluated the images using automated classification. Blinded examiners achieved a sensitivity and specificity of 99.2 ± 0.3% and 98.0 ± 0.7%, respectively, with the dye carrier method of dye application. Sensitivity and specificity was similar for dye application via a pipette (99.2 ± 0.3% and 94.0 ± 2.4%, respectively). Sensitivity and specificity for automated methods of tissue discrimination were similarly high. Human and automated classification achieved high sensitivity and specificity in discriminating atrial working myocardium and nodal tissue. We suggest that our findings facilitate clinical translation of fiber-optics confocal microscopy as an intraoperative imaging modality to reduce the incidence of conduction disturbances during surgical correction of congenital heart disease.

Comparison of the diagnostic accuracy, sensitivity and specificity of four odontological methods for age evaluation in Italian children at the age threshold of 14 years using ROC curves.

PubMed

Pinchi, Vilma; Pradella, Francesco; Vitale, Giulia; Rugo, Dario; Nieri, Michele; Norelli, Gian-Aristide

2016-01-01

The age threshold of 14 years is relevant in Italy as the minimum age for criminal responsibility. It is of utmost importance to evaluate the diagnostic accuracy of every odontological method for age evaluation considering the sensitivity, or the ability to estimate the true positive cases, and the specificity, or the ability to estimate the true negative cases. The research aims to compare the specificity and sensitivity of four commonly adopted methods of dental age estimation - Demirjian, Haavikko, Willems and Cameriere - in a sample of Italian children aged between 11 and 16 years, with an age threshold of 14 years, using receiver operating characteristic curves and the area under the curve (AUC). In addition, new decision criteria are developed to increase the accuracy of the methods. Among the four odontological methods for age estimation adopted in the research, the Cameriere method showed the highest AUC in both female and male cohorts. The Cameriere method shows a high degree of accuracy at the age threshold of 14 years. To adopt the Cameriere method to estimate the 14-year age threshold more accurately, however, it is suggested - according to the Youden index - that the decision criterion be set at the lower value of 12.928 for females and 13.258 years for males, obtaining a sensitivity of 85% and specificity of 88% in females, and a sensitivity of 77% and specificity of 92% in males. If a specificity level >90% is needed, the cut-off point should be set at 12.959 years (82% sensitivity) for females. © The Author(s) 2015.

Unlocking Sensitivity for Visibility-based Estimators of the 21 cm Reionization Power Spectrum

NASA Astrophysics Data System (ADS)

Zhang, Yunfan Gerry; Liu, Adrian; Parsons, Aaron R.

2018-01-01

Radio interferometers designed to measure the cosmological 21 cm power spectrum require high sensitivity. Several modern low-frequency interferometers feature drift-scan antennas placed on a regular grid to maximize the number of instantaneously coherent (redundant) measurements. However, even for such maximum-redundancy arrays, significant sensitivity comes through partial coherence between baselines. Current visibility-based power-spectrum pipelines, though shown to ease control of systematics, lack the ability to make use of this partial redundancy. We introduce a method to leverage partial redundancy in such power-spectrum pipelines for drift-scan arrays. Our method cross-multiplies baseline pairs at a time lag and quantifies the sensitivity contributions of each pair of baselines. Using the configurations and beams of the 128-element Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER-128) and staged deployments of the Hydrogen Epoch of Reionization Array, we illustrate how our method applies to different arrays and predict the sensitivity improvements associated with pairing partially coherent baselines. As the number of antennas increases, we find partial redundancy to be of increasing importance in unlocking the full sensitivity of upcoming arrays.

Controlled assembly of organic whispering-gallery-mode microlasers as highly sensitive chemical vapor sensors.

PubMed

Gao, Miaomiao; Wei, Cong; Lin, Xianqing; Liu, Yuan; Hu, Fengqin; Zhao, Yong Sheng

2017-03-09

We demonstrate the fabrication of organic high Q active whispering-gallery-mode (WGM) resonators from π-conjugated polymer by a controlled emulsion-solvent-evaporation method, which can simultaneously provide optical gain and act as an effective resonant cavity. By measuring the shift of their lasing modes on exposure to organic vapor, we successfully monitored the slight concentration variation in the chemical gas. These microlaser sensors demonstrated high detection sensitivity and good signal repeatability under continuous chemical gas treatments. The results offer an effective strategy to design miniaturized optical sensors.

Simple Method for Assaying Colistin Methanesulfonate in Plasma and Urine Using High-Performance Liquid Chromatography

PubMed Central

Li, Jian; Milne, Robert W.; Nation, Roger L.; Turnidge, John D.; Coulthard, Kingsley; Valentine, Jason

2002-01-01

A simple and sensitive high-performance liquid chromatographic method is described for the determination of colistimethate sodium in plasma and urine. The accuracy and reproducibility was within 10.1 and 11.2% with rat plasma and urine, respectively. Several commonly coadministered antibacterial agents do not interfere with the assay. PMID:12234867

Sensitivity of BRCA1/2 testing in high-risk breast/ovarian/male breast cancer families: little contribution of comprehensive RNA/NGS panel testing.

PubMed

Byers, Helen; Wallis, Yvonne; van Veen, Elke M; Lalloo, Fiona; Reay, Kim; Smith, Philip; Wallace, Andrew J; Bowers, Naomi; Newman, William G; Evans, D Gareth

2016-11-01

The sensitivity of testing BRCA1 and BRCA2 remains unresolved as the frequency of deep intronic splicing variants has not been defined in high-risk familial breast/ovarian cancer families. This variant category is reported at significant frequency in other tumour predisposition genes, including NF1 and MSH2. We carried out comprehensive whole gene RNA analysis on 45 high-risk breast/ovary and male breast cancer families with no identified pathogenic variant on exonic sequencing and copy number analysis of BRCA1/2. In addition, we undertook variant screening of a 10-gene high/moderate risk breast/ovarian cancer panel by next-generation sequencing. DNA testing identified the causative variant in 50/56 (89%) breast/ovarian/male breast cancer families with Manchester scores of ≥50 with two variants being confirmed to affect splicing on RNA analysis. RNA sequencing of BRCA1/BRCA2 on 45 individuals from high-risk families identified no deep intronic variants and did not suggest loss of RNA expression as a cause of lost sensitivity. Panel testing in 42 samples identified a known RAD51D variant, a high-risk ATM variant in another breast ovary family and a truncating CHEK2 mutation. Current exonic sequencing and copy number analysis variant detection methods of BRCA1/2 have high sensitivity in high-risk breast/ovarian cancer families. Sequence analysis of RNA does not identify any variants undetected by current analysis of BRCA1/2. However, RNA analysis clarified the pathogenicity of variants of unknown significance detected by current methods. The low diagnostic uplift achieved through sequence analysis of the other known breast/ovarian cancer susceptibility genes indicates that further high-risk genes remain to be identified.

Aptamer binding to celiac disease-triggering hydrophobic proteins: a sensitive gluten detection approach.

PubMed

Amaya-González, Sonia; de-Los-Santos-Álvarez, Noemí; Miranda-Ordieres, Arturo J; Lobo-Castañón, M Jesús

2014-03-04

Celiac disease represents a significant public health problem in large parts of the world. A major hurdle in the effective management of the disease by celiac sufferers is the sensitivity of the current available methods for assessing gluten contents in food. In response, we report a highly sensitive approach for gluten analysis using aptamers as specific receptors. Gliadins, a fraction of gluten proteins, are the main constituent responsible for triggering the disease. However, they are highly hydrophobic and large molecules, regarded as difficult targets for in vitro evolution of aptamers without nucleobase modification. We describe the successful selection of aptamers for these water insoluble prolamins that was achieved choosing the immunodominant apolar peptide from α2-gliadin as a target for selection. All aptamers evolved are able to bind the target in its native environment within the natural protein. The best nonprotein receptor is the basis for an electrochemical competitive enzyme-linked assay on magnetic particles, which allows the measurement of as low as 0.5 ppb of gliadin standard (0.5 ppm of gluten). Reference immunoassay for detecting the same target has a limit of detection of 3 ppm, 6 times less sensitive than this method. Importantly, it also displays high specificity, detecting the other three prolamins toxic for celiac patients and not showing cross-reactivity to nontoxic proteins such as maize, soya, and rice. These features make the proposed method a valuable tool for gluten detection in foods.

A sensitive LC-MS/MS method for simultaneous determination of amygdalin and paeoniflorin in human plasma and its application.

PubMed

Li, Xiaobing; Shi, Fuguo; Gu, Pan; Liu, Lingye; He, Hua; Ding, Li

2014-04-01

A simple and sensitive HPLC-MS/MS method was developed and fully validated for the simultaneous determination of amygdalin (AD) and paeoniflorin (PF) in human plasma. For both analytes, the method exhibited high sensitivity (LLOQs of 0.6ng/mL) by selecting the ammonium adduct ions ([M+NH4](+)) as the precursor ions and good linearity over the concentration range of 0.6-2000ng/mL with the correlation coefficients>0.9972. The intra- and inter-day precision was lower than 10% in relation to relative standard deviation, while accuracy was within ±2.3% in terms of relative error for both analytes. The developed method was successfully applied to a pilot pharmacokinetic study of AD and PF in healthy volunteers after intravenous infusion administration of Huoxue-Tongluo lyophilized powder for injection. Copyright © 2014 Elsevier B.V. All rights reserved.

Sensitivity analysis and nonlinearity assessment of steam cracking furnace process

NASA Astrophysics Data System (ADS)

Rosli, M. N.; Sudibyo, Aziz, N.

2017-11-01

In this paper, sensitivity analysis and nonlinearity assessment of cracking furnace process are presented. For the sensitivity analysis, the fractional factorial design method is employed as a method to analyze the effect of input parameters, which consist of four manipulated variables and two disturbance variables, to the output variables and to identify the interaction between each parameter. The result of the factorial design method is used as a screening method to reduce the number of parameters, and subsequently, reducing the complexity of the model. It shows that out of six input parameters, four parameters are significant. After the screening is completed, step test is performed on the significant input parameters to assess the degree of nonlinearity of the system. The result shows that the system is highly nonlinear with respect to changes in an air-to-fuel ratio (AFR) and feed composition.

Combining Monte Carlo methods with coherent wave optics for the simulation of phase-sensitive X-ray imaging

PubMed Central

Peter, Silvia; Modregger, Peter; Fix, Michael K.; Volken, Werner; Frei, Daniel; Manser, Peter; Stampanoni, Marco

2014-01-01

Phase-sensitive X-ray imaging shows a high sensitivity towards electron density variations, making it well suited for imaging of soft tissue matter. However, there are still open questions about the details of the image formation process. Here, a framework for numerical simulations of phase-sensitive X-ray imaging is presented, which takes both particle- and wave-like properties of X-rays into consideration. A split approach is presented where we combine a Monte Carlo method (MC) based sample part with a wave optics simulation based propagation part, leading to a framework that takes both particle- and wave-like properties into account. The framework can be adapted to different phase-sensitive imaging methods and has been validated through comparisons with experiments for grating interferometry and propagation-based imaging. The validation of the framework shows that the combination of wave optics and MC has been successfully implemented and yields good agreement between measurements and simulations. This demonstrates that the physical processes relevant for developing a deeper understanding of scattering in the context of phase-sensitive imaging are modelled in a sufficiently accurate manner. The framework can be used for the simulation of phase-sensitive X-ray imaging, for instance for the simulation of grating interferometry or propagation-based imaging. PMID:24763652

Molecular beacon-based real-time PCR method for detection of porcine DNA in gelatin and gelatin capsules.

PubMed

Mohamad, Nurhidayatul Asma; Mustafa, Shuhaimi; Khairil Mokhtar, Nur Fadhilah; El Sheikha, Aly Farag

2018-03-05

The pharmaceutical industry has boosted gelatin consumption worldwide. This is supported by the availability of cost-effective gelatin production from porcine by-products. However, cross-contamination of gelatin materials, where porcine gelatin was unintentionally included in the other animal sources of gelatin, has caused significant concerns about halal authenticity. The real-time polymerase chain reaction (PCR) has enabled a highly specific and sensitive animal species detection method in various food products. Hence, such a technique was employed in the present study to detect and quantify porcine DNA in gelatin using a molecular beacon probe, with differences in performance between mitochondrial (cytochrome b gene) and chromosomal DNA-(MPRE42 repetitive element) based porcine-specific PCR assays being compared. A higher sensitivity was observed in chromosomal DNA (MPRE-PCR assay), where this assay allows the detection of gelatin DNA at amounts as as low as 1 pg, whereas mitochondrial DNA (CBH-PCR assay) can only detect at levels down to 10 pg of gelatin DNA. When an analysis with commercial gelatin and gelatin capsule samples was conducted, the same result was observed, with a significantly more sensitive detection being provided by the repetitive element of chromosomal DNA. The present study has established highly sensitive DNA-based porcine detection systems derived from chromosomal DNA that are feasible for highly processed products such as gelatin and gelatin capsules containing a minute amount of DNA. This sensitive detection method can also be implemented to assist the halal authentication process of various food products available on the market. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Fluorescence ELISA based on glucose oxidase-mediated fluorescence quenching of quantum dots for highly sensitive detection of Hepatitis B.

PubMed

Wu, Yunqing; Zeng, Lifeng; Xiong, Ying; Leng, Yuankui; Wang, Hui; Xiong, Yonghua

2018-05-01

Herein, we present a novel sandwich fluorescence enzyme linked immunosorbent assay (ELISA) for highly sensitive detection of Hepatitis B virus surface antigen (HBsAg) based on glucose oxidase (GOx)-induced fluorescence quenching of mercaptopropionic acid-modified CdTe quantum dots (MPA-QDs). In this system, hydrogen peroxide (H 2 O 2 ) sensitive MPA-QDs was used as a signal output, and glucose oxidase (GOx) was used as label which can generate H 2 O 2 via catalytic oxidation of glucose. The proposed method showed dynamic linear detection of HBsAg both in the range of 47pgmL -1 ~ 380pgmL -1 and 0.75ngmL -1 ~ 12.12ngmL -1 . The detection limit of the proposed fluorescence ELISA was 1.16pgmL -1 , which was approximately 430-fold lower than that of horseradish peroxidase (HRP)-based conventional ELISA. The average recoveries for HBsAg-spiked serum samples ranged from 98.0% to 126.8% with the relative standard derivation below 10%, thus indicating acceptable precision and high reproducibility of the proposed fluorescence ELISA for HBsAg detection. Additionally, the developed method showed no false positive results analyzing 35 real HBsAg-negative serum samples, and exhibited excellent agreement (R 2 =0.9907) with a commercial time-resolved fluorescence immunoassay (TRFIA) kit for detecting 31 HBsAg-positive serum samples. In summary, the proposed method based on fluorescence quenching of H 2 O 2 sensitive QDs is considerably to be an excellent biodetection platform with ultrahigh sensitivity, good accuracy and excellent reliability. Copyright © 2018 Elsevier B.V. All rights reserved.

Sensitive determination of D-lactic acid and L-lactic acid in urine by high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Henry, H; Marmy Conus, N; Steenhout, P; Béguin, A; Boulat, O

2012-04-01

D-lactic acid in urine originates mainly from bacterial production in the intestinal tract. Increased D-lactate excretion as observed in patients affected by short bowel syndrome or necrotizing enterocolitis reflects D-lactic overproduction. Therefore, there is a need for a reliable and sensitive method able to detect D-lactic acid even at subclinical elevation levels. A new and highly sensitive method for the simultaneous determination of L- and D-lactic acid by a two-step procedure has been developed. This method is based on the concentration of lactic acid enantiomers from urine by supported liquid extraction followed by high-performance liquid chromatography-tandem mass spectrometry. The separation was achieved by the use of an Astec Chirobiotic™ R chiral column under isocratic conditions. The calibration curves were linear over the ranges of 2-400 and 0.5-100 µmol/L respectively for L- and D-lactic acid. The limit of detection of D-lactic acid was 0.125 µmol/L and its limit of quantification was 0.5 µmol/L. The overall accuracy and precision were well within 10% of the nominal values. The developed method is suitable for production of reference values in children and could be applied for accurate routine analysis. Copyright © 2011 John Wiley & Sons, Ltd.

Comparison of the sensitivity of mass spectrometry atmospheric pressure ionization techniques in the analysis of porphyrinoids.

PubMed

Swider, Paweł; Lewtak, Jan P; Gryko, Daniel T; Danikiewicz, Witold

2013-10-01

The porphyrinoids chemistry is greatly dependent on the data obtained in mass spectrometry. For this reason, it is essential to determine the range of applicability of mass spectrometry ionization methods. In this study, the sensitivity of three different atmospheric pressure ionization techniques, electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization, was tested for several porphyrinods and their metallocomplexes. Electrospray ionization method was shown to be the best ionization technique because of its high sensitivity for derivatives of cyanocobalamin, free-base corroles and porphyrins. In the case of metallocorroles and metalloporphyrins, atmospheric pressure photoionization with dopant proved to be the most sensitive ionization method. It was also shown that for relatively acidic compounds, particularly for corroles, the negative ion mode provides better sensitivity than the positive ion mode. The results supply a lot of relevant information on the methodology of porphyrinoids analysis carried out by mass spectrometry. The information can be useful in designing future MS or liquid chromatography-MS experiments. Copyright © 2013 John Wiley & Sons, Ltd.

Nanophotonics of biomaterials and inorganic nanostructures

NASA Astrophysics Data System (ADS)

Petrik, P.; Agocs, E.; Kalas, B.; Fodor, B.; Lohner, T.; Nador, J.; Saftics, A.; Kurunczi, S.; Novotny, T.; Perez-Feró, E.; Nagy, R.; Hamori, A.; Horvath, R.; Hózer, Z.; Fried, M.

2017-01-01

Optical methods have been used for the sensitive characterization of surfaces and thin films for more than a century. The first ellipsometric measurement was conducted on metal surfaces by Paul Drude in 1889. The word ‘ellipsometer’ was first used by Rothen in a study of antigen-antibody interactions on polished metal surfaces in 1945. The ‘bible’ of ellipsometry has been published in the second half of the ‘70s. The publications in the topic of ellipsometry started to increase rapidly by the end of the ‘80s, together with concepts like surface plasmon resonance, later new topics like photonic crystals emerged. These techniques find applications in many fields, including sensorics or photovoltaics. In optical sensorics, the highest sensitivities were achieved by waveguide interferometry and plasmon resonance configurations. The instrumentation of ellipsometry is also being developed intensively towards higher sensitivity and performance by combinations with plasmonics, scatterometry, imaging or waveguide methods, utilizing the high sensitivity, high speed, non-destructive nature and mapping capabilities. Not only the instrumentation but also the methods of evaluation show a significant development, which leads to the characterization of structures with increasing complexity, including photonic, porous or metal surfaces. This article discusses a selection of interesting applications of photonics in the Centre for Energy Research of the Hungarian Academy of Sciences.

Global sensitivity analysis for urban water quality modelling: Terminology, convergence and comparison of different methods

NASA Astrophysics Data System (ADS)

Vanrolleghem, Peter A.; Mannina, Giorgio; Cosenza, Alida; Neumann, Marc B.

2015-03-01

Sensitivity analysis represents an important step in improving the understanding and use of environmental models. Indeed, by means of global sensitivity analysis (GSA), modellers may identify both important (factor prioritisation) and non-influential (factor fixing) model factors. No general rule has yet been defined for verifying the convergence of the GSA methods. In order to fill this gap this paper presents a convergence analysis of three widely used GSA methods (SRC, Extended FAST and Morris screening) for an urban drainage stormwater quality-quantity model. After the convergence was achieved the results of each method were compared. In particular, a discussion on peculiarities, applicability, and reliability of the three methods is presented. Moreover, a graphical Venn diagram based classification scheme and a precise terminology for better identifying important, interacting and non-influential factors for each method is proposed. In terms of convergence, it was shown that sensitivity indices related to factors of the quantity model achieve convergence faster. Results for the Morris screening method deviated considerably from the other methods. Factors related to the quality model require a much higher number of simulations than the number suggested in literature for achieving convergence with this method. In fact, the results have shown that the term "screening" is improperly used as the method may exclude important factors from further analysis. Moreover, for the presented application the convergence analysis shows more stable sensitivity coefficients for the Extended-FAST method compared to SRC and Morris screening. Substantial agreement in terms of factor fixing was found between the Morris screening and Extended FAST methods. In general, the water quality related factors exhibited more important interactions than factors related to water quantity. Furthermore, in contrast to water quantity model outputs, water quality model outputs were found to be characterised by high non-linearity.

MPAI (mass probes aided ionization) method for total analysis of biomolecules by mass spectrometry.

PubMed

Honda, Aki; Hayashi, Shinichiro; Hifumi, Hiroki; Honma, Yuya; Tanji, Noriyuki; Iwasawa, Naoko; Suzuki, Yoshio; Suzuki, Koji

2007-01-01

We have designed and synthesized various mass probes, which enable us to effectively ionize various molecules to be detected with mass spectrometry. We call the ionization method using mass probes the "MPAI (mass probes aided ionization)" method. We aim at the sensitive detection of various biological molecules, and also the detection of bio-molecules by a single mass spectrometry serially without changing the mechanical settings. Here, we review mass probes for small molecules with various functional groups and mass probes for proteins. Further, we introduce newly developed mass probes for proteins for highly sensitive detection.

Dual channel sensitive detection of hsa-miR-21 based on rolling circle amplification and quantum dots tagging.

PubMed

Wangt, Dan-Chen; Hu, Li-Hui; Zhou, Yu-Hui; Huang, Yu-Ting; Li, Xinhua; Zhu, Jun-Jie

2014-04-01

An isothermal, highly sensitive and specific assay for the detection of hsa-miR-21 with the integration of QDs tagging and rolling circle amplification was offered. In addition, a dual channel strategy for miRNA detection was proposed: anodic stripping voltammetry (ASV) and fluorescent method were both performed for the final Cd2+ signal readout. The designed strategy exhibited good specificity to hsa-miR-21 and presented comparable detection results by detection methods.

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1971-01-01

The development of methods of measurement for semiconductor materials, process control, and devices is discussed. The following subjects are also presented: (1) demonstration of the high sensitivity of the infrared response technique by the identification of gold in a germanium diode, (2) verification that transient thermal response is significantly more sensitive to the presence of voids in die attachment than steady-state thermal resistance, and (3) development of equipment for determining susceptibility of transistors to hot spot formation by the current-gain technique.

The wavefield of acoustic logging in a cased hole with a single casing—Part II: a dipole tool

NASA Astrophysics Data System (ADS)

Wang, Hua; Fehler, Michael

2018-02-01

The acoustic method, being the most effective method for cement bond evaluation, has been used by industry for more than a half century. However, the methods currently used are almost always focused on the first arrival (especially for sonic logging), which has limitations. We use a 3-D finite-difference method to numerically simulate the wavefields from a dipole source in a single-cased hole with different cement conditions. By using wavefield snapshots and dispersion curves, we interpret the characteristics of the modes in the models. We investigate the effect of source frequency, the thickness and location of fluid columns on different modes. The dipole wavefield in a single-cased hole consists of a leaky P (for frequency >10 kHz) from formation, formation flexural, and also some casing modes. Depending on the mode, their behaviour is sometimes sensitive to the existence of fluid between the cement and formation and sometimes sensitive to the existence of fluid between the casing and cement. The formation S velocity can be obtained from the formation flexural mode at low frequency. However, interference from high-order casing modes makes the leaky P invisible and P velocity determination difficult when the casing is not well cemented. The dispersion curve of the formation flexural mode is sensitive to the fluid thickness when fluid exists only at the interface between casing and cement. The fundamental casing dipole mode is only sensitive to the total fluid thickness in the annulus between casing and formation. Either the arrival time or amplitude of the high-order casing dipole mode is sensitive to the fluid column when the fluid column is next to the casing. We provide a table that summarizes the ability of different modes to detect fluid columns between various layers of casing, cement and formation. Based on the results, we suggest a data processing flow for field application, which will highly improve cement evaluation.

Precisely Controlled Ultrathin Conjugated Polymer Films for Large Area Transparent Transistors and Highly Sensitive Chemical Sensors.

PubMed

Khim, Dongyoon; Ryu, Gi-Seong; Park, Won-Tae; Kim, Hyunchul; Lee, Myungwon; Noh, Yong-Young

2016-04-13

A uniform ultrathin polymer film is deposited over a large area with molecularlevel precision by the simple wire-wound bar-coating method. The bar-coated ultrathin films not only exhibit high transparency of up to 90% in the visible wavelength range but also high charge carrier mobility with a high degree of percolation through the uniformly covered polymer nanofibrils. They are capable of realizing highly sensitive multigas sensors and represent the first successful report of ethylene detection using a sensor based on organic field-effect transistors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

LASER BIOLOGY AND MEDICINE: Application of tunable diode lasers for a highly sensitive analysis of gaseous biomarkers in exhaled air

NASA Astrophysics Data System (ADS)

Stepanov, E. V.; Milyaev, Varerii A.

2002-11-01

The application of tunable diode lasers for a highly sensitive analysis of gaseous biomarkers in exhaled air in biomedical diagnostics is discussed. The principle of operation and the design of a laser analyser for studying the composition of exhaled air are described. The results of detection of gaseous biomarkers in exhaled air, including clinical studies, which demonstrate the diagnostic possibilities of the method, are presented.

Method and apparatus for detection of charge on ions and particles

DOEpatents

Fuerstenau, Stephen Douglas; Soli, George Arthur

2002-01-01

The present invention provides a tessellated array detector with charge collecting plate (or cup) electrode pixels and amplifying circuitry integrated into each pixel making it sensitive to external electrostatic charge; a micro collector/amplifier pixel design possessing a small capacitance to ensure a high charge to voltage signal conversion for low noise/high sensitivity operation; a micro-fabricated array of such pixels to create a useful macroscopic target area for ion and charged particle collection.

Conductive fiber-based ultrasensitive textile pressure sensor for wearable electronics.

PubMed

Lee, Jaehong; Kwon, Hyukho; Seo, Jungmok; Shin, Sera; Koo, Ja Hoon; Pang, Changhyun; Son, Seungbae; Kim, Jae Hyung; Jang, Yong Hoon; Kim, Dae Eun; Lee, Taeyoon

2015-04-17

A flexible and sensitive textile-based pressure sensor is developed using highly conductive fibers coated with dielectric rubber materials. The pressure sensor exhibits superior sensitivity, very fast response time, and high stability, compared with previous textile-based pressure sensors. By using a weaving method, the pressure sensor can be applied to make smart gloves and clothes that can control machines wirelessly as human-machine interfaces. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of method using phase-sensitive motion estimator with speckle tracking method and application to measurement of arterial wall motion

NASA Astrophysics Data System (ADS)

Miyajo, Akira; Hasegawa, Hideyuki

2018-07-01

At present, the speckle tracking method is widely used as a two- or three-dimensional (2D or 3D) motion estimator for the measurement of cardiovascular dynamics. However, this method requires high-level interpolation of a function, which evaluates the similarity between ultrasonic echo signals in two frames, to estimate a subsample small displacement in high-frame-rate ultrasound, which results in a high computational cost. To overcome this problem, a 2D motion estimator using the 2D Fourier transform, which does not require any interpolation process, was proposed by our group. In this study, we compared the accuracies of the speckle tracking method and our method using a 2D motion estimator, and applied the proposed method to the measurement of motion of a human carotid arterial wall. The bias error and standard deviation in the lateral velocity estimates obtained by the proposed method were 0.048 and 0.282 mm/s, respectively, which were significantly better than those (‑0.366 and 1.169 mm/s) obtained by the speckle tracking method. The calculation time of the proposed phase-sensitive method was 97% shorter than the speckle tracking method. Furthermore, the in vivo experimental results showed that a characteristic change in velocity around the carotid bifurcation could be detected by the proposed method.

Sensitivity analysis and approximation methods for general eigenvalue problems

NASA Technical Reports Server (NTRS)

Murthy, D. V.; Haftka, R. T.

1986-01-01

Optimization of dynamic systems involving complex non-hermitian matrices is often computationally expensive. Major contributors to the computational expense are the sensitivity analysis and reanalysis of a modified design. The present work seeks to alleviate this computational burden by identifying efficient sensitivity analysis and approximate reanalysis methods. For the algebraic eigenvalue problem involving non-hermitian matrices, algorithms for sensitivity analysis and approximate reanalysis are classified, compared and evaluated for efficiency and accuracy. Proper eigenvector normalization is discussed. An improved method for calculating derivatives of eigenvectors is proposed based on a more rational normalization condition and taking advantage of matrix sparsity. Important numerical aspects of this method are also discussed. To alleviate the problem of reanalysis, various approximation methods for eigenvalues are proposed and evaluated. Linear and quadratic approximations are based directly on the Taylor series. Several approximation methods are developed based on the generalized Rayleigh quotient for the eigenvalue problem. Approximation methods based on trace theorem give high accuracy without needing any derivatives. Operation counts for the computation of the approximations are given. General recommendations are made for the selection of appropriate approximation technique as a function of the matrix size, number of design variables, number of eigenvalues of interest and the number of design points at which approximation is sought.

Quantum Dot-Fullerene Based Molecular Beacon Nanosensors for Rapid, Highly Sensitive Nucleic Acid Detection.

PubMed

Liu, Ye; Kannegulla, Akash; Wu, Bo; Cheng, Li-Jing

2018-05-15

Spherical fullerene (C 60 ) can quench the fluorescence of a quantum dot (QD) through energy transfer and charge transfer processes, with the quenching efficiency regulated by the number of proximate C 60 on each QD. With the quenching property and its small size compared with other nanoparticle-based quenchers, it is advantageous to group a QD reporter and multiple C 60 -labeled oligonucleotide probes to construct a molecular beacon (MB) probe for sensitive, robust nucleic acid detection. We demonstrated a rapid, high-sensitivity DNA detection method using the nanosensors composed of QD-C 60 based MBs carried by magnetic nanoparticles (MNPs). The assay was accelerated by first dispersing the nanosensors in analytes for highly efficient DNA capture resulting from short-distance 3-dimensional diffusion of targets to the sensor surface and then concentrating the nanosensors to a substrate by magnetic force to amplify the fluorescence signal for target quantification. The enhanced mass transport enabled a rapid detection (< 10 min) with a small sample volume (1-10 µl). The high signal-to-noise ratio produced by the QD-C 60 pairs and magnetic concentration yielded a detection limit of 100 fM (~106 target DNA copies for a 10 µl analyte). The rapid, sensitive, label-free detection method will benefit the applications in point-of-care molecular diagnostic technologies.

Characterization of an intraluminal differential frequency-domain photoacoustics system

NASA Astrophysics Data System (ADS)

Lashkari, Bahman; Son, Jungik; Liang, Simon; Castelino, Robin; Foster, F. Stuart; Courtney, Brian; Mandelis, Andreas

2016-03-01

Cardiovascular related diseases are ranked as the second highest cause of death in Canada. Among the most important cardiovascular diseases is atherosclerosis. Current methods of diagnosis of atherosclerosis consist of angiography, intravascular ultrasound (IVUS) and optical coherence tomography (OCT). None of these methods possesses adequate sensitivity, as the ideal technique should be capable of both depth profiling, as well as functional imaging. An alternative technique is photoacoustics (PA) which can perform deep imaging and spectroscopy. The presented study explores the application of wavelength-modulated differential photoacoustic radar (WM-DPAR) for characterizing arterial vessels. The wavelength-modulated differential photoacoustic technique was shown to be able to substantially increase the dynamic range and sensitivity of hemoglobin oxygenation level detection. In this work the differential PA technique was used with a very high frequency modulation range. To perform spectroscopic PA imaging, at least two wavelengths are required. The selected wavelengths for this work are 1210 nm and 980 nm. 1210 nm corresponds to the maximum optical absorption coefficient of cholesterol and cholesteryl esters which are the main constituents of plaques. Since water, elastin and collagen also have high absorption coefficients at 1210 nm, this wavelength alone cannot provide very high sensitivity and specificity. The additional wavelength, 980 nm corresponds to high absorption coefficient of those constituents of healthy artery tissue. The simultaneous application of the abovementioned wavelengths can provide higher sensitivity and improved specificity in detecting lipids in the arterial vessels.

Directional Sensitivity in Light-Mass Dark Matter Searches with Single-Electron-Resolution Ionization Detectors

NASA Astrophysics Data System (ADS)

Kadribasic, Fedja; Mirabolfathi, Nader; Nordlund, Kai; Sand, Andrea E.; Holmström, Eero; Djurabekova, Flyura

2018-03-01

We propose a method using solid state detectors with directional sensitivity to dark matter interactions to detect low-mass weakly interacting massive particles (WIMPs) originating from galactic sources. In spite of a large body of literature for high-mass WIMP detectors with directional sensitivity, no available technique exists to cover WIMPs in the mass range <1 GeV /c2 . We argue that single-electron-resolution semiconductor detectors allow for directional sensitivity once properly calibrated. We examine the commonly used semiconductor material response to these low-mass WIMP interactions.

An optimized rapid bisulfite conversion method with high recovery of cell-free DNA.

PubMed

Yi, Shaohua; Long, Fei; Cheng, Juanbo; Huang, Daixin

2017-12-19

Methylation analysis of cell-free DNA is a encouraging tool for tumor diagnosis, monitoring and prognosis. Sensitivity of methylation analysis is a very important matter due to the tiny amounts of cell-free DNA available in plasma. Most current methods of DNA methylation analysis are based on the difference of bisulfite-mediated deamination of cytosine between cytosine and 5-methylcytosine. However, the recovery of bisulfite-converted DNA based on current methods is very poor for the methylation analysis of cell-free DNA. We optimized a rapid method for the crucial steps of bisulfite conversion with high recovery of cell-free DNA. A rapid deamination step and alkaline desulfonation was combined with the purification of DNA on a silica column. The conversion efficiency and recovery of bisulfite-treated DNA was investigated by the droplet digital PCR. The optimization of the reaction results in complete cytosine conversion in 30 min at 70 °C and about 65% of recovery of bisulfite-treated cell-free DNA, which is higher than current methods. The method allows high recovery from low levels of bisulfite-treated cell-free DNA, enhancing the analysis sensitivity of methylation detection from cell-free DNA.

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.

Integrated digital error suppression for improved detection of circulating tumor DNA

PubMed Central

Kurtz, David M.; Chabon, Jacob J.; Scherer, Florian; Stehr, Henning; Liu, Chih Long; Bratman, Scott V.; Say, Carmen; Zhou, Li; Carter, Justin N.; West, Robert B.; Sledge, George W.; Shrager, Joseph B.; Loo, Billy W.; Neal, Joel W.; Wakelee, Heather A.; Diehn, Maximilian; Alizadeh, Ash A.

2016-01-01

High-throughput sequencing of circulating tumor DNA (ctDNA) promises to facilitate personalized cancer therapy. However, low quantities of cell-free DNA (cfDNA) in the blood and sequencing artifacts currently limit analytical sensitivity. To overcome these limitations, we introduce an approach for integrated digital error suppression (iDES). Our method combines in silico elimination of highly stereotypical background artifacts with a molecular barcoding strategy for the efficient recovery of cfDNA molecules. Individually, these two methods each improve the sensitivity of cancer personalized profiling by deep sequencing (CAPP-Seq) by ~3 fold, and synergize when combined to yield ~15-fold improvements. As a result, iDES-enhanced CAPP-Seq facilitates noninvasive variant detection across hundreds of kilobases. Applied to clinical non-small cell lung cancer (NSCLC) samples, our method enabled biopsy-free profiling of EGFR kinase domain mutations with 92% sensitivity and 96% specificity and detection of ctDNA down to 4 in 105 cfDNA molecules. We anticipate that iDES will aid the noninvasive genotyping and detection of ctDNA in research and clinical settings. PMID:27018799

Ab initio structure determination of nanocrystals of organic pharmaceutical compounds by electron diffraction at room temperature using a Timepix quantum area direct electron detector

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

Genderen, E. van; Clabbers, M. T. B.; Center for Cellular Imaging and NanoAnalytics

A specialized quantum area detector for electron diffraction studies makes it possible to solve the structure of small organic compound nanocrystals in non-cryo conditions by direct methods. Until recently, structure determination by transmission electron microscopy of beam-sensitive three-dimensional nanocrystals required electron diffraction tomography data collection at liquid-nitrogen temperature, in order to reduce radiation damage. Here it is shown that the novel Timepix detector combines a high dynamic range with a very high signal-to-noise ratio and single-electron sensitivity, enabling ab initio phasing of beam-sensitive organic compounds. Low-dose electron diffraction data (∼0.013 e{sup −} Å{sup −2} s{sup −1}) were collected at roommore » temperature with the rotation method. It was ascertained that the data were of sufficient quality for structure solution using direct methods using software developed for X-ray crystallography (XDS, SHELX) and for electron crystallography (ADT3D/PETS, SIR2014)« less

The parallel reaction monitoring method contributes to a highly sensitive polyubiquitin chain quantification

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

Tsuchiya, Hikaru; Tanaka, Keiji, E-mail: tanaka-kj@igakuken.or.jp; Saeki, Yasushi, E-mail: saeki-ys@igakuken.or.jp

2013-06-28

Highlights: •The parallel reaction monitoring method was applied to ubiquitin quantification. •The ubiquitin PRM method is highly sensitive even in biological samples. •Using the method, we revealed that Ufd4 assembles the K29-linked ubiquitin chain. -- Abstract: Ubiquitylation is an essential posttranslational protein modification that is implicated in a diverse array of cellular functions. Although cells contain eight structurally distinct types of polyubiquitin chains, detailed function of several chain types including K29-linked chains has remained largely unclear. Current mass spectrometry (MS)-based quantification methods are highly inefficient for low abundant atypical chains, such as K29- and M1-linked chains, in complex mixtures thatmore » typically contain highly abundant proteins. In this study, we applied parallel reaction monitoring (PRM), a quantitative, high-resolution MS method, to quantify ubiquitin chains. The ubiquitin PRM method allows us to quantify 100 attomole amounts of all possible ubiquitin chains in cell extracts. Furthermore, we quantified ubiquitylation levels of ubiquitin-proline-β-galactosidase (Ub-P-βgal), a historically known model substrate of the ubiquitin fusion degradation (UFD) pathway. In wild-type cells, Ub-P-βgal is modified with ubiquitin chains consisting of 21% K29- and 78% K48-linked chains. In contrast, K29-linked chains are not detected in UFD4 knockout cells, suggesting that Ufd4 assembles the K29-linked ubiquitin chain(s) on Ub-P-βgal in vivo. Thus, the ubiquitin PRM is a novel, useful, quantitative method for analyzing the highly complicated ubiquitin system.« less

Development of Fluorescent Polymerization-based Signal Amplification for Sensitive and Non-enzymatic Biodetection in Antibody Microarrays

PubMed Central

Avens, Heather J.; Bowman, Christopher N.

2009-01-01

Antibody microarrays are a critical tool for proteomics, requiring broad, highly sensitive detection of numerous low abundance biomarkers. Fluorescent polymerization-based amplification (FPBA) is presented as a novel, non-enzymatic signal amplification method that takes advantage of the chain-reaction nature of radical polymerization to achieve a highly amplified fluorescent response. A streptavidin-eosin conjugate localizes eosin photoinitiators for polymerization on the chip where biotinylated target protein is bound. The chip is contacted with acrylamide as a monomer, N-methyldiethanolamine as a coinitiator and yellow/green fluorescent nanoparticles (NPs) which, upon initiation, combine to form a macroscopically visible and highly fluorescent film. The rapid polymerization kinetics and the presence of cross-linker favor entrapment of the fluorescent NPs in the polymer, enabling highly sensitive fluorescent biodetection. This method is demonstrated as being appropriate for antibody microarrays and is compared to detection approaches which utilize streptavidin-FITC (SA-FITC) and streptavidin-labeled yellow/green NPs (SA-NPs). It is found that FPBA is able to detect 0.16 (+/− 0.01) biotin-antibody/µm2 (or 40 zeptomole surface-bound target molecules), while SA-FITC has a limit of detection of 31 (+/− 1) biotin-antibody/µm2 and SA-NPs fail to achieve any significant signal under the conditions evaluated here. Further, FPBA in conjunction with fluorescent stereomicroscopy yields equal or better sensitivity compared to fluorescent detection of SA-eosin using a much more costly microarray scanner. By facilitating highly sensitive detection, FPBA is expected to enable detection of low abundance antigens and also make possible a transition towards less expensive fluorescence detection instrumentation. PMID:19508906

High PRF ultrafast sliding compound doppler imaging: fully qualitative and quantitative analysis of blood flow

NASA Astrophysics Data System (ADS)

Kang, Jinbum; Jang, Won Seuk; Yoo, Yangmo

2018-02-01

Ultrafast compound Doppler imaging based on plane-wave excitation (UCDI) can be used to evaluate cardiovascular diseases using high frame rates. In particular, it provides a fully quantifiable flow analysis over a large region of interest with high spatio-temporal resolution. However, the pulse-repetition frequency (PRF) in the UCDI method is limited for high-velocity flow imaging since it has a tradeoff between the number of plane-wave angles (N) and acquisition time. In this paper, we present high PRF ultrafast sliding compound Doppler imaging method (HUSDI) to improve quantitative flow analysis. With the HUSDI method, full scanline images (i.e. each tilted plane wave data) in a Doppler frame buffer are consecutively summed using a sliding window to create high-quality ensemble data so that there is no reduction in frame rate and flow sensitivity. In addition, by updating a new compounding set with a certain time difference (i.e. sliding window step size or L), the HUSDI method allows various Doppler PRFs with the same acquisition data to enable a fully qualitative, retrospective flow assessment. To evaluate the performance of the proposed HUSDI method, simulation, in vitro and in vivo studies were conducted under diverse flow circumstances. In the simulation and in vitro studies, the HUSDI method showed improved hemodynamic representations without reducing either temporal resolution or sensitivity compared to the UCDI method. For the quantitative analysis, the root mean squared velocity error (RMSVE) was measured using 9 angles (-12° to 12°) with L of 1-9, and the results were found to be comparable to those of the UCDI method (L  =  N  =  9), i.e.  ⩽0.24 cm s-1, for all L values. For the in vivo study, the flow data acquired from a full cardiac cycle of the femoral vessels of a healthy volunteer were analyzed using a PW spectrogram, and arterial and venous flows were successfully assessed with high Doppler PRF (e.g. 5 kHz at L  =  4). These results indicate that the proposed HUSDI method can improve flow visualization and quantification with a higher frame rate, PRF and flow sensitivity in cardiovascular imaging.

High PRF ultrafast sliding compound doppler imaging: fully qualitative and quantitative analysis of blood flow.

PubMed

Kang, Jinbum; Jang, Won Seuk; Yoo, Yangmo

2018-02-09

Ultrafast compound Doppler imaging based on plane-wave excitation (UCDI) can be used to evaluate cardiovascular diseases using high frame rates. In particular, it provides a fully quantifiable flow analysis over a large region of interest with high spatio-temporal resolution. However, the pulse-repetition frequency (PRF) in the UCDI method is limited for high-velocity flow imaging since it has a tradeoff between the number of plane-wave angles (N) and acquisition time. In this paper, we present high PRF ultrafast sliding compound Doppler imaging method (HUSDI) to improve quantitative flow analysis. With the HUSDI method, full scanline images (i.e. each tilted plane wave data) in a Doppler frame buffer are consecutively summed using a sliding window to create high-quality ensemble data so that there is no reduction in frame rate and flow sensitivity. In addition, by updating a new compounding set with a certain time difference (i.e. sliding window step size or L), the HUSDI method allows various Doppler PRFs with the same acquisition data to enable a fully qualitative, retrospective flow assessment. To evaluate the performance of the proposed HUSDI method, simulation, in vitro and in vivo studies were conducted under diverse flow circumstances. In the simulation and in vitro studies, the HUSDI method showed improved hemodynamic representations without reducing either temporal resolution or sensitivity compared to the UCDI method. For the quantitative analysis, the root mean squared velocity error (RMSVE) was measured using 9 angles (-12° to 12°) with L of 1-9, and the results were found to be comparable to those of the UCDI method (L  =  N  =  9), i.e.  ⩽0.24 cm s -1 , for all L values. For the in vivo study, the flow data acquired from a full cardiac cycle of the femoral vessels of a healthy volunteer were analyzed using a PW spectrogram, and arterial and venous flows were successfully assessed with high Doppler PRF (e.g. 5 kHz at L  =  4). These results indicate that the proposed HUSDI method can improve flow visualization and quantification with a higher frame rate, PRF and flow sensitivity in cardiovascular imaging.

Ultra high vacuum pumping system and high sensitivity helium leak detector

DOEpatents

Myneni, Ganapati Rao

1997-01-01

An improved helium leak detection method and apparatus are disclosed which increase the leak detection sensitivity to 10.sup.-13 atm cc s.sup.-1. The leak detection sensitivity is improved over conventional leak detectors by completely eliminating the use of o-rings, equipping the system with oil-free pumping systems, and by introducing measured flows of nitrogen at the entrances of both the turbo pump and backing pump to keep the system free of helium background. The addition of dry nitrogen flows to the system reduces backstreaming of atmospheric helium through the pumping system as a result of the limited compression ratios of the pumps for helium.

Protein detection system

DOEpatents

Fruetel, Julie A [Livermore, CA; Fiechtner, Gregory J [Bethesda, MD; Kliner, Dahv A. V. [San Ramon, CA; McIlroy, Andrew [Livermore, CA

2009-05-05

The present embodiment describes a miniature, microfluidic, absorption-based sensor to detect proteins at sensitivities comparable to LIF but without the need for tagging. This instrument utilizes fiber-based evanescent-field cavity-ringdown spectroscopy, in combination with faceted prism microchannels. The combination of these techniques will increase the effective absorption path length by a factor of 10.sup.3 to 10.sup.4 (to .about.1-m), thereby providing unprecedented sensitivity using direct absorption. The coupling of high-sensitivity absorption with high-performance microfluidic separation will enable real-time sensing of biological agents in aqueous samples (including aerosol collector fluids) and will provide a general method with spectral fingerprint capability for detecting specific bio-agents.

Aptamer-based microspheres for highly sensitive protein detection using fluorescently-labeled DNA nanostructures.

PubMed

Han, Daehoon; Hong, Jinkee; Kim, Hyun Cheol; Sung, Jong Hwan; Lee, Jong Bum

2013-11-01

Many highly sensitive protein detection techniques have been developed and have played an important role in the analysis of proteins. Herein, we report a novel technique that can detect proteins sensitively and effectively using aptamer-based DNA nanostructures. Thrombin was used as a target protein and aptamer was used to capture fluorescent dye-labeled DNA nanobarcodes or thrombin on a microsphere. The captured DNA nanobarcodes were replaced by a thrombin and aptamer interaction. The detection ability of this approach was confirmed by flow cytometry with different concentrations of thrombin. Our detection method has great potential for rapid and simple protein detection with a variety of aptamers.

Biomagnetic separation of Salmonella Typhimurium with high affine and specific ligand peptides isolated by phage display technique

NASA Astrophysics Data System (ADS)

Steingroewer, Juliane; Bley, Thomas; Bergemann, Christian; Boschke, Elke

2007-04-01

Analyses of food-borne pathogens are of great importance in order to minimize the health risk for customers. Thus, very sensitive and rapid detection methods are required. Current conventional culture techniques are very time consuming. Modern immunoassays and biochemical analysis also require pre-enrichment steps resulting in a turnaround time of at least 24 h. Biomagnetic separation (BMS) is a promising more rapid method. In this study we describe the isolation of high affine and specific peptides from a phage-peptide library, which combined with BMS allows the detection of Salmonella spp. with a similar sensitivity as that of immunomagnetic separation using antibodies.

[Comparative research into sensitivity and specificity of immune-enzyme analysis with chemiluminescence and colorimetric detection for detecting antigens and antibodies to avian influenza viruses and newcastle disease].

PubMed

Vitkova, O N; Kapustina, T P; Mikhailova, V V; Safonov, G A; Vlasova, N N; Belousova, R V

2015-01-01

The goal of this work was to demonstrate the results of the development of the enzyme-linked immunosorbent tests with chemiluminescence detection and colorimetric detection of specific viral antigens and antibodies for identifying the avian influenza and the Newcastle disease viruses: high sensitivity and specificity of the immuno- chemiluminescence assay, which are 10-50 times higher than those of the ELISA colorimetric method. The high effectiveness of the results and the automation of the process of laboratory testing (using a luminometer) allow these methods to be recommended for including in primary screening tests for these infectious diseases.

Novel approach based on one-tube nested PCR and a lateral flow strip for highly sensitive diagnosis of tuberculous meningitis.

PubMed

Sun, Yajuan; Chen, Jiajun; Li, Jia; Xu, Yawei; Jin, Hui; Xu, Na; Yin, Rui; Hu, Guohua

2017-01-01

Rapid and sensitive detection of Mycobacterium tuberculosis (M. Tb) in cerebrospinal fluid is crucial in the diagnosis of tuberculous meningitis (TBM), but conventional diagnostic technologies have limited sensitivity and specificity or are time-consuming. In this work, a novel, highly sensitive molecular diagnostic method, one-tube nested PCR-lateral flow strip test (OTNPCR-LFST), was developed for detecting M. tuberculosis. This one-tube nested PCR maintains the sensitivity of conventional two-step nested PCR and reduces both the chance of cross-contamination and the time required for analysis. The PCR product was detected by a lateral flow strip assay, which provided a basis for migration of the test to a point-of-care (POC) microfluidic format. The developed assay had an improved sensitivity compared with traditional PCR, and the limit of detection was up to 1 fg DNA isolated from M. tuberculosis. The assay was also specific for M. tuberculosis, and no cross-reactions were found in other non-target bacteria. The application of this technique to clinical samples was successfully evaluated, and OTNPCR-LFST showed 89% overall sensitivity and 100% specificity for TBM patients. This one-tube nested PCR-lateral flow strip assay is useful for detecting M. tuberculosis in TBM due to its rapidity, high sensitivity and simple manipulation.

Analysis and amelioration about the cross-sensitivity of a high resolution MOEMS accelerometer based on diffraction grating

NASA Astrophysics Data System (ADS)

Lu, Qianbo; Bai, Jian; Wang, Kaiwei; Lou, Shuqi; Jiao, Xufen; Han, Dandan

2016-10-01

Cross-sensitivity is a crucial parameter since it detrimentally affect the performance of an accelerometer, especially for a high resolution accelerometer. In this paper, a suite of analytical and finite-elements-method (FEM) models for characterizing the mechanism and features of the cross-sensitivity of a single-axis MOEMS accelerometer composed of a diffraction grating and a micromachined mechanical sensing chip are presented, which have not been systematically investigated yet. The mechanism and phenomena of the cross-sensitivity of this type MOEMS accelerometer based on diffraction grating differ quite a lot from the traditional ones owing to the identical sensing principle. By analyzing the models, some ameliorations and the modified design are put forward to suppress the cross-sensitivity. The modified design, achieved by double sides etching on a specific double-substrate-layer silicon-on-insulator (SOI) wafer, is validated to have a far smaller cross-sensitivity compared with the design previously reported in the literature. Moreover, this design can suppress the cross-sensitivity dramatically without compromising the acceleration sensitivity and resolution.

Effect of parameters in moving average method for event detection enhancement using phase sensitive OTDR

NASA Astrophysics Data System (ADS)

Kwon, Yong-Seok; Naeem, Khurram; Jeon, Min Yong; Kwon, Il-bum

2017-04-01

We analyze the relations of parameters in moving average method to enhance the event detectability of phase sensitive optical time domain reflectometer (OTDR). If the external events have unique frequency of vibration, then the control parameters of moving average method should be optimized in order to detect these events efficiently. A phase sensitive OTDR was implemented by a pulsed light source, which is composed of a laser diode, a semiconductor optical amplifier, an erbium-doped fiber amplifier, a fiber Bragg grating filter, and a light receiving part, which has a photo-detector and high speed data acquisition system. The moving average method is operated with the control parameters: total number of raw traces, M, number of averaged traces, N, and step size of moving, n. The raw traces are obtained by the phase sensitive OTDR with sound signals generated by a speaker. Using these trace data, the relation of the control parameters is analyzed. In the result, if the event signal has one frequency, then the optimal values of N, n are existed to detect the event efficiently.

Rapid and sensitive detection of human astrovirus in water samples by loop-mediated isothermal amplification with hydroxynaphthol blue dye

PubMed Central

2014-01-01

Background The aim of this paper was to develop a reverse transcription loop-mediated isothermal amplification (RT-LAMP) method for rapid, sensitive and inexpensive detection of astrovirus. Results The detection limit of LAMP using in vitro RNA transcripts was 3.6×10 copies·μL-1, which is as sensitive as the presently used PCR assays. However, the LAMP products could be identified as different colors with the naked eye following staining with hydroxynaphthol blue dye (HNB). No cross-reactivity with other gastroenteric viruses (rotavirus and norovirus) was observed, indicating the relatively high specificity of LAMP. The RT-LAMP method with HNB was used to effectively detect astrovirus in reclaimed water samples. Conclusions The LAMP technique described in this study is a cheap, sensitive, specific and rapid method for the detection of astrovirus. The RT-LAMP method can be simply applied for the specific detection of astrovirus and has the potential to be utilized in the field as a screening test. PMID:24524254

Multi-test cervical cancer diagnosis with missing data estimation

NASA Astrophysics Data System (ADS)

Xu, Tao; Huang, Xiaolei; Kim, Edward; Long, L. Rodney; Antani, Sameer

2015-03-01

Cervical cancer is a leading most common type of cancer for women worldwide. Existing screening programs for cervical cancer suffer from low sensitivity. Using images of the cervix (cervigrams) as an aid in detecting pre-cancerous changes to the cervix has good potential to improve sensitivity and help reduce the number of cervical cancer cases. In this paper, we present a method that utilizes multi-modality information extracted from multiple tests of a patient's visit to classify the patient visit to be either low-risk or high-risk. Our algorithm integrates image features and text features to make a diagnosis. We also present two strategies to estimate the missing values in text features: Image Classifier Supervised Mean Imputation (ICSMI) and Image Classifier Supervised Linear Interpolation (ICSLI). We evaluate our method on a large medical dataset and compare it with several alternative approaches. The results show that the proposed method with ICSLI strategy achieves the best result of 83.03% specificity and 76.36% sensitivity. When higher specificity is desired, our method can achieve 90% specificity with 62.12% sensitivity.

Three-dimensional Fréchet sensitivity kernels for electromagnetic wave propagation

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

Strickland, C. E.; Johnson, T. C.; Odom, R. I.

2015-08-28

Electromagnetic imaging methods are useful tools for monitoring subsurface changes in pore-fluid content and the associated changes in electrical permittivity and conductivity. The most common method for georadar tomography uses a high frequency ray-theoretic approximation that is valid when material variations are sufficiently small relative to the wavelength of the propagating wave. Georadar methods, however, often utilize electromagnetic waves that propagate within heterogeneous media at frequencies where ray theory may not be applicable. In this paper we describe the 3-D Fréchet sensitivity kernels for EM wave propagation. Various data functional types are formulated that consider all three components of themore » electric wavefield and incorporate near-, intermediate-, and far-field contributions. We show that EM waves exhibit substantial variations for different relative source-receiver component orientations. The 3-D sensitivities also illustrate out-of-plane effects that are not captured in 2-D sensitivity kernels and can influence results obtained using 2-D inversion methods to image structures that are in reality 3-D.« less

Highly sensitive analysis of polycyclic aromatic hydrocarbons in environmental water with porous cellulose/zeolitic imidazolate framework-8 composite microspheres as a novel adsorbent coupled with high-performance liquid chromatography.

PubMed

Liang, Xiaotong; Liu, Shengquan; Zhu, Rong; Xiao, Lixia; Yao, Shouzhuo

2016-07-01

In this work, novel cellulose/zeolitic imidazolate frameworks-8 composite microspheres have been successfully fabricated and utilized as sorbent for environmental polycyclic aromatic hydrocarbons efficient extraction and sensitive analysis. The composite microspheres were synthesized through the in situ hydrothermal growth of zeolitic imidazolate frameworks-8 on cellulose matrix, and exhibited favorable hierarchical structure with chemical composition as assumed through scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction patterns, and Brunauer-Emmett-Teller surface areas characterization. A robust and highly efficient method was then successfully developed with as-prepared composite microspheres as novel solid-phase extraction sorbent with optimum extraction conditions, such as sorbent amount, sample volume, extraction time, desorption conditions, volume of organic modifier, and ionic strength. The method exhibited high sensitivity with low limit of detection down to 0.1-1.0 ng/L and satisfactory linearity with correlation coefficients ranging from 0.9988 to 0.9999, as well as good recoveries of 66.7-121.2% with relative standard deviations less than 10% for environmental polycyclic aromatic hydrocarbons analysis. Thus, our method was convenient and efficient for polycyclic aromatic hydrocarbons extraction and detection, potential for future environmental water samples analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Effect of inoculum size on sensitivity and specificity of the double-disk synergy test for the detection of wide-spectrum beta-lactamases].

PubMed

Bedenić, B; Boras, A

2001-01-01

The plasmid-mediated extended-spectrum beta-lactamases (ESBL) confer resistance to oxymino-cephalosporins, such as cefotaxime, ceftazidime, and ceftriaxone and to monobactams such as aztreonam. It is well known fact that ESBL producing bacteria exhibit a pronounced inoculum effect against broad spectrum cephalosporins like ceftazidime, cefotaxime, ceftriaxone and cefoperazone. The aim of this investigation was to determine the effect of inoculum size on the sensitivity and specificity of double-disk synergy test (DDST) which is the test most frequently used for detection of ESBLs, in comparison with other two methods (determination of ceftazidime MIC with and without clavulanate and inhibitor potentiated disk-diffusion test) which are seldom used in clinical laboratories. The experiments were performed on a set of K. pneumoniae strains with previously characterized beta-lactamases which comprise: 10 SHV-5 beta-lactamase producing K. pneumoniae, 20 SHV-2 + 1 SHV 2a beta-lactamase producing K. pneumoniae, 7 SHV-12 beta-lactamase producing K. pneumoniae, 39 putative SHV ESBL producing K. pneumoniae and 26 K. pneumoniae isolates highly susceptible to ceftazidime according to Kirby-Bauer disk-diffusion method and thus considered to be ESBL negative. According to the results of this investigation, increase in inoculum size affected more significantly the sensitivity of DDST than of other two methods. The sensitivity of the DDST was lower when a higher inoculum size of 10(8) CFU/ml was applied, in distinction from other two methods (MIC determination and inhibitor potentiated disk-diffusion test) which retained high sensitivity regardless of the density of bacterial suspension. On the other hand, DDST displayed higher specificity compared to other two methods regardless of the inoculum size. This investigation found that DDST is a reliable method but it is important to standardize the inoculum size.

Sensitivity of high-frequency Rayleigh-wave data revisited

USGS Publications Warehouse

Xia, J.; Miller, R.D.; Ivanov, J.

2007-01-01

Rayleigh-wave phase velocity of a layered earth model is a function of frequency and four groups of earth properties: P-wave velocity, S-wave velocity (Vs), density, and thickness of layers. Analysis of the Jacobian matrix (or the difference method) provides a measure of dispersion curve sensitivity to earth properties. Vs is the dominant influence for the fundamental mode (Xia et al., 1999) and higher modes (Xia et al., 2003) of dispersion curves in a high frequency range (>2 Hz) followed by layer thickness. These characteristics are the foundation of determining S-wave velocities by inversion of Rayleigh-wave data. More applications of surface-wave techniques show an anomalous velocity layer such as a high-velocity layer (HVL) or a low-velocity layer (LVL) commonly exists in near-surface materials. Spatial location (depth) of an anomalous layer is usually the most important information that surface-wave techniques are asked to provide. Understanding and correctly defining the sensitivity of high-frequency Rayleigh-wave data due to depth of an anomalous velocity layer are crucial in applying surface-wave techniques to obtain a Vs profile and/or determine the depth of an anomalous layer. Because depth is not a direct earth property of a layered model, changes in depth will result in changes in other properties. Modeling results show that sensitivity at a given depth calculated by the difference method is dependent on the Vs difference (contrast) between an anomalous layer and surrounding layers. The larger the contrast is, the higher the sensitivity due to depth of the layer. Therefore, the Vs contrast is a dominant contributor to sensitivity of Rayleigh-wave data due to depth of an anomalous layer. Modeling results also suggest that the most sensitive depth for an HVL is at about the middle of the depth to the half-space, but for an LVL it is near the ground surface. ?? 2007 Society of Exploration Geophysicists.

High sensitivity liquid phase measurements using broadband cavity enhanced absorption spectroscopy (BBCEAS) featuring a low cost webcam based prism spectrometer.

PubMed

Qu, Zhechao; Engstrom, Julia; Wong, Donald; Islam, Meez; Kaminski, Clemens F

2013-11-07

Cavity enhanced techniques enable high sensitivity absorption measurements in the liquid phase but are typically more complex, and much more expensive, to perform than conventional absorption methods. The latter attributes have so far prevented a wide spread use of these methods in the analytical sciences. In this study we demonstrate a novel BBCEAS instrument that is sensitive, yet simple and economical to set up and operate. We use a prism spectrometer with a low cost webcam as the detector in conjunction with an optical cavity consisting of two R = 0.99 dielectric mirrors and a white light LED source for illumination. High sensitivity liquid phase measurements were made on samples contained in 1 cm quartz cuvettes placed at normal incidence to the light beam in the optical cavity. The cavity enhancement factor (CEF) with water as the solvent was determined directly by phase shift cavity ring down spectroscopy (PS-CRDS) and also by calibration with Rhodamine 6G solutions. Both methods yielded closely matching CEF values of ~60. The minimum detectable change in absorption (αmin) was determined to be 6.5 × 10(-5) cm(-1) at 527 nm and was limited only by the 8 bit resolution of the particular webcam detector used, thus offering scope for further improvement. The instrument was used to make representative measurements on dye solutions and in the determination of nitrite concentrations in a variation of the widely used Griess Assay. Limits of detection (LOD) were ~850 pM for Rhodamine 6G and 3.7 nM for nitrite, respectively. The sensitivity of the instrument compares favourably with previous cavity based liquid phase studies whilst being achieved at a small fraction of the cost hitherto reported, thus opening the door to widespread use in the community. Further means of improving sensitivity are discussed in the paper.

Evaluation of a High-Throughput Peptide Reactivity Format Assay for Assessment of the Skin Sensitization Potential of Chemicals

PubMed Central

Wong, Chin Lin; Lam, Ai-Leen; Smith, Maree T.; Ghassabian, Sussan

2016-01-01

The direct peptide reactivity assay (DPRA) is a validated method for in vitro assessment of the skin sensitization potential of chemicals. In the present work, we describe a peptide reactivity assay using 96-well plate format and systematically identified the optimal assay conditions for accurate and reproducible classification of chemicals with known sensitizing capacity. The aim of the research is to ensure that the analytical component of the peptide reactivity assay is robust, accurate, and reproducible in accordance with criteria that are used for the validation of bioanalytical methods. Analytical performance was evaluated using quality control samples (QCs; heptapeptides at low, medium, and high concentrations) and incubation of control chemicals (chemicals with known sensitization capacity, weak, moderate, strong, extreme, and non-sensitizers) with each of three synthetic heptapeptides, viz Cor1-C420 (Ac-NKKCDLF), cysteine- (Ac-RFAACAA), and lysine- (Ac-RFAAKAA) containing heptapeptides. The optimal incubation temperature for all three heptapeptides was 25°C. Apparent heptapeptide depletion was affected by vial material composition. Incubation of test chemicals with Cor1-C420, showed that peptide depletion was unchanged in polypropylene vials over 3-days storage in an autosampler but this was not the case for borosilicate glass vials. For cysteine-containing heptapeptide, the concentration was not stable by day 3 post-incubation in borosilicate glass vials. Although the lysine-containing heptapeptide concentration was unchanged in both polypropylene and borosilicate glass vials, the apparent extent of lysine-containing heptapeptide depletion by ethyl acrylate, differed between polypropylene (24.7%) and glass (47.3%) vials. Additionally, the peptide-chemical complexes for Cor1-C420-cinnamaldehyde and cysteine-containing heptapeptide-2, 4-dinitrochlorobenzene were partially reversible during 3-days of autosampler storage. These observations further highlight the difficulty in adapting in vitro methods to high-throughput format for screening the skin sensitization potential of large numbers of chemicals whilst ensuring that the data produced are both accurate and reproducible. PMID:27014067

Rapid and sensitive detection of Yersinia pestis using amplification of plague diagnostic bacteriophages monitored by real-time PCR.

PubMed

Sergueev, Kirill V; He, Yunxiu; Borschel, Richard H; Nikolich, Mikeljon P; Filippov, Andrey A

2010-06-28

Yersinia pestis, the agent of plague, has caused many millions of human deaths and still poses a serious threat to global public health. Timely and reliable detection of such a dangerous pathogen is of critical importance. Lysis by specific bacteriophages remains an essential method of Y. pestis detection and plague diagnostics. The objective of this work was to develop an alternative to conventional phage lysis tests--a rapid and highly sensitive method of indirect detection of live Y. pestis cells based on quantitative real-time PCR (qPCR) monitoring of amplification of reporter Y. pestis-specific bacteriophages. Plague diagnostic phages phiA1122 and L-413C were shown to be highly effective diagnostic tools for the detection and identification of Y. pestis by using qPCR with primers specific for phage DNA. The template DNA extraction step that usually precedes qPCR was omitted. phiA1122-specific qPCR enabled the detection of an initial bacterial concentration of 10(3) CFU/ml (equivalent to as few as one Y. pestis cell per 1-microl sample) in four hours. L-413C-mediated detection of Y. pestis was less sensitive (up to 100 bacteria per sample) but more specific, and thus we propose parallel qPCR for the two phages as a rapid and reliable method of Y. pestis identification. Importantly, phiA1122 propagated in simulated clinical blood specimens containing EDTA and its titer rise was detected by both a standard plating test and qPCR. Thus, we developed a novel assay for detection and identification of Y. pestis using amplification of specific phages monitored by qPCR. The method is simple, rapid, highly sensitive, and specific and allows the detection of only live bacteria.

Highly sensitive detection of the PIK3CA (H1047R) mutation in colorectal cancer using a novel PCR-RFLP method.

PubMed

Li, Wan-Ming; Hu, Ting-Ting; Zhou, Lin-Lin; Feng, Yi-Ming; Wang, Yun-Yi; Fang, Jin

2016-07-12

The PIK3CA (H1047R) mutation is considered to be a potential predictive biomarker for EGFR-targeted therapies. In this study, we developed a novel PCR-PFLP approach to detect the PIK3CA (H1047R) mutation in high effectiveness. A 126-bp fragment of PIK3CA exon-20 was amplified by PCR, digested with FspI restriction endonuclease and separated by 3 % agarose gel electrophoresis for the PCR-RFLP analysis. The mutant sequence of the PIK3CA (H1047R) was spiked into the corresponding wild-type sequence in decreasing ratios for sensitivity analysis. Eight-six cases of formalin-fixed paraffin-embedded colorectal cancer (CRC) specimens were subjected to PCR-RFLP to evaluate the applicability of the method. The PCR-RFLP method had a capability to detect as litter as 0.4 % of mutation, and revealed 16.3 % of the PIK3CA (H1047R) mutation in 86 CRC tissues, which was significantly higher than that discovered by DNA sequencing (9.3 %). A positive association between the PIK3CA (H1047R) mutation and the patients' age was first found, except for the negative relationship with the degree of tumor differentiation. In addition, the highly sensitive detection of a combinatorial mutation of PIK3CA, KRAS and BRAF was achieved using individual PCR-RFLP methods. We developed a sensitive, simple and rapid approach to detect the low-abundance PIK3CA (H1047R) mutation in real CRC specimens, providing an effective tool for guiding cancer targeted therapy.

Genetics-based methods for detection of Salmonella spp. in foods.

PubMed

Mozola, Mark A

2006-01-01

Genetic methods are now at the forefront of foodborne pathogen testing. The sensitivity, specificity, and inclusivity advantages offered by deoxyribonucleic acid (DNA) probe technology have driven an intense effort in methods development over the past 20 years. DNA probe-based methods for Salmonella spp. and other pathogens have progressed from time-consuming procedures involving the use of radioisotopes to simple, high throughput, automated assays. The analytical sensitivity of nucleic acid amplification technology has facilitated a reduction in analysis time by allowing enriched samples to be tested for previously undetectable quantities of analyte. This article will trace the evolution of the development of genetic methods for detection of Salmonella in foods, review the basic assay formats and their advantages and limitations, and discuss method performance characteristics and considerations for selection of methods.

Ultra-high sensitivity radiation detection apparatus and method

DOEpatents

Gross, Kenneth C.; Valentine, John D.; Markum, Francis; Zawadzki, Mary; Dickerman, Charles

1999-01-01

A method and apparatus are provided to concentrate and detect very low levels of radioactive noble gases from the atmosphere. More specifically the invention provides a method and apparatus to concentrate xenon, krypton and radon in an organic fluid and to detect these gases by the radioactive emissions.

Development of LC/MS/MS Methods for Implementation in US EPA’s Drinking Water Unregulated Contaminant Monitoring Regulations

EPA Science Inventory

Well-characterized and standardized methods are the foundation upon which monitoring of regulated and unregulated contaminants in drinking water are based. To obtain reliable, high quality data for trace analysis of contaminants, these methods must be rugged, selective and sensit...

Early diagnosis of blast fungus, Magnaporthe oryzae, in rice plant by using an ultra-sensitive electrically magnetic-controllable electrochemical biosensor.

PubMed

Yang, Weijuan; Zhang, Hongyan; Li, Mengxue; Wang, Zonghua; Zhou, Jie; Wang, Shihua; Lu, Guodong; Fu, FengFu

2014-11-19

As one of the most destructive and widespread disease of rice, Magnaporthe oryzae (also called Magnaporthe grisea) has a significant negative impact on rice production. Therefore, it is still in high demand to develop extremely sensitive and accurate methods for the early diagnosis of Magnaporthe oryzae (M. oryzae). In this study, we developed a novel magnetic-controllable electrochemical biosensor for the ultra sensitive and specific detection of M. oryzae in rice plant by using M. oryzae's chitinases (Mgchi) as biochemical marker and a rice (Oryza sativa) cDNA encoding mannose-binding jacalin-related lectin (Osmbl) as recognition probe. The proposed biosensor combined with the merits of chronoamperometry, electrically magnetic-controllable gold electrode and magnetic beads (MBs)-based palladium nano-particles (PdNPs) catalysis amplification, has an ultra-high sensitivity and specificity for the detection of trace M. oryzae in rice plant. It could be used to detect M. oryzae in rice plant in the initial infection stage (before any symptomatic lesions were observed) to help farmers timely manage the disease. In comparison with previous methods, the proposed method has notable advantages such as higher sensitivity, excellent specificity, short analysis time, robust resistibility to complex matrix and low cost etc. The success in this study provides a reliable approach for the early diagnosis and fast screening of M. oryzae in rice plant. Copyright © 2014 Elsevier B.V. All rights reserved.

Construction of optical glucose nanobiosensor with high sensitivity and selectivity at physiological pH on the basis of organic-inorganic hybrid microgels.

PubMed

Wu, Weitai; Zhou, Ting; Aiello, Michael; Zhou, Shuiqin

2010-08-15

A new class of optical glucose nanobiosensors with high sensitivity and selectivity at physiological pH is described. To construct these glucose nanobiosensors, the fluorescent CdS quantum dots (QDs), serving as the optical code, were incorporated into the glucose-sensitive poly(N-isopropylacrylamide-acrylamide-2-acrylamidomethyl-5-fluorophenylboronic acid) copolymer microgels, via both in situ growth method and "breathing in" method, respectively. The polymeric gel can adapt to surrounding glucose concentrations, and regulate the fluorescence of the embedded QDs, converting biochemical signals into optical signals. The gradual swelling of the gel would lead to the quenching of the fluorescence at the elevated glucose concentrations. The hybrid microgels displayed high selectivity to glucose over the potential primary interferents of lactate and human serum albumin in the physiologically important glucose concentration range. The stability, reversibility, and sensitivity of the organic-inorganic hybrid microgel-based biosensors were also systematically studied. These general properties of our nanobiosensors are well tunable under appropriate tailor on the hybrid microgels, in particular, simply through the change in the crosslinking degree of the microgels. The optical glucose nanobiosensors based on the organic-inorganic hybrid microgels have shown the potential for a third generation fluorescent biosensor. Copyright 2010 Elsevier B.V. All rights reserved.

Recombinase Polymerase Amplification Compared to Real-Time Polymerase Chain Reaction Test for the Detection of Fasciola hepatica in Human Stool

PubMed Central

Cabada, Miguel M.; Malaga, Jose L.; Castellanos-Gonzalez, Alejandro; Bagwell, Kelli A.; Naeger, Patrick A.; Rogers, Hayley K.; Maharsi, Safa; Mbaka, Maryann; White, A. Clinton

2017-01-01

Fasciola hepatica is the most widely distributed trematode infection in the world. Control efforts may be hindered by the lack of diagnostic capacity especially in remote endemic areas. Polymerase chain reaction (PCR)–based methods offer high sensitivity and specificity but require expensive technology. However, the recombinase polymerase amplification (RPA) is an efficient isothermal method that eliminates the need for a thermal cycler and has a high deployment potential to resource-limited settings. We report on the characterization of RPA and PCR tests to detect Fasciola infection in clinical stool samples with low egg burdens. The sensitivity of the RPA and PCR were 87% and 66%, respectively. Both tests were 100% specific showing no cross-reactivity with trematode, cestode, or nematode parasites. In addition, RPA and PCR were able to detect 47% and 26% of infections not detected by microscopy, respectively. The RPA adapted to a lateral flow platform was more sensitive than gel-based detection of the reaction products. In conclusion, the Fasciola RPA is a highly sensitive and specific test to diagnose chronic infection using stool samples. The Fasciola RPA lateral flow has the potential for deployment to endemic areas after further characterization. PMID:27821691

A highly sensitive monoclonal antibody based biosensor for quantifying 3-5 ring polycyclic aromatic hydrocarbons (PAHs) in aqueous environmental samples

PubMed Central

Li, Xin; Kaattari, Stephen L.; Vogelbein, Mary A.; Vadas, George G.; Unger, Michael A.

2016-01-01

Immunoassays based on monoclonal antibodies (mAbs) are highly sensitive for the detection of polycyclic aromatic hydrocarbons (PAHs) and can be employed to determine concentrations in near real-time. A sensitive generic mAb against PAHs, named as 2G8, was developed by a three-step screening procedure. It exhibited nearly uniformly high sensitivity against 3-ring to 5-ring unsubstituted PAHs and their common environmental methylated PAHs, with IC50 values between 1.68–31 μg/L (ppb). 2G8 has been successfully applied on the KinExA Inline Biosensor system for quantifying 3-5 ring PAHs in aqueous environmental samples. PAHs were detected at a concentration as low as 0.2 μg/L. Furthermore, the analyses only required 10 min for each sample. To evaluate the accuracy of the 2G8-based biosensor, the total PAH concentrations in a series of environmental samples analyzed by biosensor and GC-MS were compared. In most cases, the results yielded a good correlation between methods. This indicates that generic antibody 2G8 based biosensor possesses significant promise for a low cost, rapid method for PAH determination in aqueous samples. PMID:26925369

HCPCF-based in-line fiber Fabry-Perot refractometer and high sensitivity signal processing method

NASA Astrophysics Data System (ADS)

Liu, Xiaohui; Jiang, Mingshun; Sui, Qingmei; Geng, Xiangyi; Song, Furong

2017-12-01

An in-line fiber Fabry-Perot interferometer (FPI) based on the hollow-core photonic crystal fiber (HCPCF) for refractive index (RI) measurement is proposed in this paper. The FPI is formed by splicing both ends of a short section of the HCPCF to single mode fibers (SMFs) and cleaving the SMF pigtail to a proper length. The RI response of the sensor is analyzed theoretically and demonstrated experimentally. The results show that the FPI sensor has linear response to external RI and good repeatability. The sensitivity calculated from the maximum fringe contrast is -136 dB/RIU. A new spectrum differential integration (SDI) method for signal processing is also presented in this study. In this method, the RI is obtained from the integrated intensity of the absolute difference between the interference spectrum and its smoothed spectrum. The results show that the sensitivity obtained from the integrated intensity is about -1.34×105 dB/RIU. Compared with the maximum fringe contrast method, the new SDI method can provide the higher sensitivity, better linearity, improved reliability, and accuracy, and it's also convenient for automatic and fast signal processing in real-time monitoring of RI.

A simple and sensitive enzymatic method for cholesterol quantification in macrophages and foam cells

PubMed Central

Robinet, Peggy; Wang, Zeneng; Hazen, Stanley L.; Smith, Jonathan D.

2010-01-01

A precise and sensitive method for measuring cellular free and esterified cholesterol is required in order to perform studies of macrophage cholesterol loading, metabolism, storage, and efflux. Until now, the use of an enzymatic cholesterol assay, commonly used for aqueous phase plasma cholesterol assays, has not been optimized for use with solid phase samples such as cells, due to inefficient solubilization of total cholesterol in enzyme compatible solvents. We present an efficient solubilization protocol compatible with an enzymatic cholesterol assay that does not require chemical saponification or chromatographic separation. Another issue with enzyme compatible solvents is the presence of endogenous peroxides that interfere with the enzymatic cholesterol assay. We overcame this obstacle by pretreatment of the reaction solution with the enzyme catalase, which consumed endogenous peroxides resulting in reduced background and increased sensitivity in our method. Finally, we demonstrated that this method for cholesterol quantification in macrophages yields results that are comparable to those measured by stable isotope dilution gas chromatography with mass spectrometry detection. In conclusion, we describe a sensitive, simple, and high-throughput enzymatic method to quantify cholesterol in complex matrices such as cells. PMID:20688754

Sensitive analytical method for simultaneous analysis of some vasoconstrictors with highly overlapped analytical signals

NASA Astrophysics Data System (ADS)

Nikolić, G. S.; Žerajić, S.; Cakić, M.

2011-10-01

Multivariate calibration method is a powerful mathematical tool that can be applied in analytical chemistry when the analytical signals are highly overlapped. The method with regression by partial least squares is proposed for the simultaneous spectrophotometric determination of adrenergic vasoconstrictors in decongestive solution containing two active components: phenyleprine hydrochloride and trimazoline hydrochloride. These sympathomimetic agents are that frequently associated in pharmaceutical formulations against the common cold. The proposed method, which is, simple and rapid, offers the advantages of sensitivity and wide range of determinations without the need for extraction of the vasoconstrictors. In order to minimize the optimal factors necessary to obtain the calibration matrix by multivariate calibration, different parameters were evaluated. The adequate selection of the spectral regions proved to be important on the number of factors. In order to simultaneously quantify both hydrochlorides among excipients, the spectral region between 250 and 290 nm was selected. A recovery for the vasoconstrictor was 98-101%. The developed method was applied to assay of two decongestive pharmaceutical preparations.

Analysis of imazaquin in soybeans by solid-phase extraction and high-performance liquid chromatography.

PubMed

Guo, C; Hu, J-Y; Chen, X-Y; Li, J-Z

2008-02-01

An analytical method for the determination imazaquin residues in soybeans was developed. The developed liquid/liquid partition and strong anion exchange solid-phase extraction procedures provide the effective cleanup, removing the greatest number of sample matrix interferences. By optimizing mobile-phase pH water/acetonitrile conditions with phosphoric acid, using a C-18 reverse-phase chromatographic column and employing ultraviolet detection, excellent peak resolution was achieved. The combined cleanup and chromatographic method steps reported herein were sensitive and reliable for determining the imazaquin residues in soybean samples. This method is characterized by recovery >88.4%, precision <6.7% CV, and sensitivity of 0.005 ppm, in agreement with directives for method validation in residue analysis. Imazaquin residues in soybeans were further confirmed by high performance liquid chromatography-mass spectrometry (LC-MS). The proposed method was successfully applied to the analysis of imazaquin residues in soybean samples grown in an experimental field after treatments of imazaquin formulation.

Systematic Development and Validation of a Thin-Layer Densitometric Bioanalytical Method for Estimation of Mangiferin Employing Analytical Quality by Design (AQbD) Approach

PubMed Central

Khurana, Rajneet Kaur; Rao, Satish; Beg, Sarwar; Katare, O.P.; Singh, Bhupinder

2016-01-01

The present work aims at the systematic development of a simple, rapid and highly sensitive densitometry-based thin-layer chromatographic method for the quantification of mangiferin in bioanalytical samples. Initially, the quality target method profile was defined and critical analytical attributes (CAAs) earmarked, namely, retardation factor (Rf), peak height, capacity factor, theoretical plates and separation number. Face-centered cubic design was selected for optimization of volume loaded and plate dimensions as the critical method parameters selected from screening studies employing D-optimal and Plackett–Burman design studies, followed by evaluating their effect on the CAAs. The mobile phase containing a mixture of ethyl acetate : acetic acid : formic acid : water in a 7 : 1 : 1 : 1 (v/v/v/v) ratio was finally selected as the optimized solvent for apt chromatographic separation of mangiferin at 262 nm with Rf 0.68 ± 0.02 and all other parameters within the acceptance limits. Method validation studies revealed high linearity in the concentration range of 50–800 ng/band for mangiferin. The developed method showed high accuracy, precision, ruggedness, robustness, specificity, sensitivity, selectivity and recovery. In a nutshell, the bioanalytical method for analysis of mangiferin in plasma revealed the presence of well-resolved peaks and high recovery of mangiferin. PMID:26912808

Methods for elimination of dampness in Building walls

NASA Astrophysics Data System (ADS)

Campian, Cristina; Pop, Maria

2016-06-01

Dampness elimination in building walls is a very sensitive problem, with high costs. Many methods are used, as: chemical method, electro osmotic method or physical method. The RECON method is a representative and a sustainable method in Romania. Italy has the most radical method from all methods. The technology consists in cutting the brick walls, insertion of a special plastic sheeting and injection of a pre-mixed anti-shrinking mortar.

Quantitative mass spectrometry methods for pharmaceutical analysis

PubMed Central

Loos, Glenn; Van Schepdael, Ann

2016-01-01

Quantitative pharmaceutical analysis is nowadays frequently executed using mass spectrometry. Electrospray ionization coupled to a (hybrid) triple quadrupole mass spectrometer is generally used in combination with solid-phase extraction and liquid chromatography. Furthermore, isotopically labelled standards are often used to correct for ion suppression. The challenges in producing sensitive but reliable quantitative data depend on the instrumentation, sample preparation and hyphenated techniques. In this contribution, different approaches to enhance the ionization efficiencies using modified source geometries and improved ion guidance are provided. Furthermore, possibilities to minimize, assess and correct for matrix interferences caused by co-eluting substances are described. With the focus on pharmaceuticals in the environment and bioanalysis, different separation techniques, trends in liquid chromatography and sample preparation methods to minimize matrix effects and increase sensitivity are discussed. Although highly sensitive methods are generally aimed for to provide automated multi-residue analysis, (less sensitive) miniaturized set-ups have a great potential due to their ability for in-field usage. This article is part of the themed issue ‘Quantitative mass spectrometry’. PMID:27644982

Rare Earth Fluorescent Nanomaterials for Enhanced Development of Latent Fingerprints.

PubMed

Wang, Meng; Li, Ming; Yu, Aoyang; Wu, Jian; Mao, Chuanbin

2015-12-30

The most commonly found fingerprints at crime scenes are latent and, thus, an efficient method for detecting latent fingerprints is very important. However, traditional developing techniques have drawbacks such as low developing sensitivity, high background interference, complicated operation, and high toxicity. To tackle this challenge, we have synthesized two kinds of rare earth fluorescent nanomaterials, including the fluoresce red-emitting YVO4:Eu nanocrystals and green-emitting LaPO4:Ce,Tb nanobelts, and then used them as fluorescent labels for the development of latent fingerprints with high sensitivity, high contrast, high selectivity, high efficiency, and low background interference, on various substrates including noninfiltrating materials, semi-infiltrating materials, and infiltrating materials.

Rapid diagnosis of sensitivity to ultraviolet light in fibroblasts from dermatologic disorders, with particular reference to xeroderma pigmentosum

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

Cleaver, J.E.; Thomas, G.H.

1988-04-01

A rapid and simple method for determining the sensitivity of human fibroblasts to ultraviolet light is described. As an alternative to the colony formation assay, this method can be used for the rapid diagnosis of ultraviolet light sensitivity in fibroblasts from photosensitive disorders. The method is based on growth of small numbers of cells in 1-cm wells of culture trays for 4 or more days after irradiation and determination of cell survival by the incorporation of (/sup 3/H)hypoxanthine. D37 values (the dose at which 37% of the control level of incorporation remains) obtained from this procedure showed the same relativemore » sensitivity of normal and xeroderma pigmentosum fibroblasts as was obtained by colony formation. Untransformed and SV40-transformed fibroblasts, which have different growth rates and different responses to high cell densities, gave different D37 values by this assay in culture trays as compared with colony formation. Comparison of relative sensitivities to irradiation should therefore be made only between cell types with similar growth characteristics. The similar sensitivity of normal and xeroderma pigmentosum cells to mitomycin C was also determined by this culture tray method. By increasing cell density at the beginning of the experiments, a greater capacity of group C compared with group D fibroblasts for recovery from potentially lethal damage was also detected.« less

Sensitivity-Enhanced Wearable Active Voiceprint Sensor Based on Cellular Polypropylene Piezoelectret.

PubMed

Li, Wenbo; Zhao, Sheng; Wu, Nan; Zhong, Junwen; Wang, Bo; Lin, Shizhe; Chen, Shuwen; Yuan, Fang; Jiang, Hulin; Xiao, Yongjun; Hu, Bin; Zhou, Jun

2017-07-19

Wearable active sensors have extensive applications in mobile biosensing and human-machine interaction but require good flexibility, high sensitivity, excellent stability, and self-powered feature. In this work, cellular polypropylene (PP) piezoelectret was chosen as the core material of a sensitivity-enhanced wearable active voiceprint sensor (SWAVS) to realize voiceprint recognition. By virtue of the dipole orientation control method, the air layers in the piezoelectret were efficiently utilized, and the current sensitivity was enhanced (from 1.98 pA/Hz to 5.81 pA/Hz at 115 dB). The SWAVS exhibited the superiorities of high sensitivity, accurate frequency response, and excellent stability. The voiceprint recognition system could make correct reactions to human voices by judging both the password and speaker. This study presented a voiceprint sensor with potential applications in noncontact biometric recognition and safety guarantee systems, promoting the progress of wearable sensor networks.

A novel fluorescent aptasensor for the highly sensitive and selective detection of cardiac troponin I based on a graphene oxide platform.

PubMed

Liu, Dongkui; Lu, Xing; Yang, Yiwen; Zhai, Yunyun; Zhang, Jian; Li, Lei

2018-05-04

Acute myocardial infarction (AMI) is one of the leading risks to global health. Thus, the rapid, accurate early diagnosis of AMI is highly critical. Human cardiac troponin I (cTnI) has been regarded as a golden biomarker for AMI due to its excellent selectivity. In this work, a novel fluorescent aptasensor based on a graphene oxide (GO) platform was developed for the highly sensitive and selective detection of cTnI. GO binds to the fluorescent anti-cTnI aptamer and quenches its fluorescence. In the presence of cTnI, the fluorescent anti-cTnI aptamer leaves the surface of GO, combines with cTnI because of the powerful affinity of the fluorescent anti-cTnI aptamer and cTnI, and then restores the fluorescence of the fluorescent anti-cTnI aptamer. Fluorescence-enhanced detection is highly sensitive and selective to cTnI. The method exhibited good analytical performance with a reasonable dynamic linearity at the concentration range of 0.10-6.0 ng/mL and a low detection limit of 0.07 ng/mL (S/N = 3). The fluorescent aptasensor also exhibited high selectivity toward cTnI compared with other interference proteins. The proposed method may be a potentially useful tool for cTnI determination in human serum. Graphical abstract A novel fluorescent aptasensor for the highly sensitive and selective detection of cardiac troponin I based on a graphene oxide platform.

Determination of albumin in bronchoalveolar lavage fluid by flow-injection fluorometry using chromazurol S.

PubMed

Sato, Takaji; Saito, Yoshihiro; Chikuma, Masahiko; Saito, Yutaka; Nagai, Sonoko

2008-03-01

A highly sensitive flow injection fluorometry for the determination of albumin was developed and applied to the determination of albumin in human bronchoalveolar lavage fluids (BALF). This method is based on binding of chromazurol S (CAS) to albumin. The calibration curve was linear in the range of 5-200 microg/ml of albumin. A highly linear correlation (r=0.986) was observed between the albumin level in BALF samples (n=25) determined by the proposed method and by a conventional fluorometric method using CAS (CAS manual method). The IgG interference was lower in the CAS flow injection method than in the CAS manual method. The albumin level in BALF collected from healthy volunteers (n=10) was 58.5+/-13.1 microg/ml. The albumin levels in BALF samples obtained from patients with sarcoidosis and idiopathic pulmonary fibrosis were increased. This finding shows that the determination of albumin levels in BALF samples is useful for investigating lung diseases and that CAS flow injection method is promising in the determination of trace albumin in BALF samples, because it is sensitive and precise.

Non-animal methods to predict skin sensitization (I): the Cosmetics Europe database.

PubMed

Hoffmann, Sebastian; Kleinstreuer, Nicole; Alépée, Nathalie; Allen, David; Api, Anne Marie; Ashikaga, Takao; Clouet, Elodie; Cluzel, Magalie; Desprez, Bertrand; Gellatly, Nichola; Goebel, Carsten; Kern, Petra S; Klaric, Martina; Kühnl, Jochen; Lalko, Jon F; Martinozzi-Teissier, Silvia; Mewes, Karsten; Miyazawa, Masaaki; Parakhia, Rahul; van Vliet, Erwin; Zang, Qingda; Petersohn, Dirk

2018-05-01

Cosmetics Europe, the European Trade Association for the cosmetics and personal care industry, is conducting a multi-phase program to develop regulatory accepted, animal-free testing strategies enabling the cosmetics industry to conduct safety assessments. Based on a systematic evaluation of test methods for skin sensitization, five non-animal test methods (DPRA (Direct Peptide Reactivity Assay), KeratinoSens TM , h-CLAT (human cell line activation test), U-SENS TM , SENS-IS) were selected for inclusion in a comprehensive database of 128 substances. Existing data were compiled and completed with newly generated data, the latter amounting to one-third of all data. The database was complemented with human and local lymph node assay (LLNA) reference data, physicochemical properties and use categories, and thoroughly curated. Focused on the availability of human data, the substance selection resulted nevertheless resulted in a high diversity of chemistries in terms of physico-chemical property ranges and use categories. Predictivities of skin sensitization potential and potency, where applicable, were calculated for the LLNA as compared to human data and for the individual test methods compared to both human and LLNA reference data. In addition, various aspects of applicability of the test methods were analyzed. Due to its high level of curation, comprehensiveness, and completeness, we propose our database as a point of reference for the evaluation and development of testing strategies, as done for example in the associated work of Kleinstreuer et al. We encourage the community to use it to meet the challenge of conducting skin sensitization safety assessment without generating new animal data.

Fluorescence-based assay as a new screening tool for toxic chemicals

PubMed Central

Moczko, Ewa; Mirkes, Evgeny M.; Cáceres, César; Gorban, Alexander N.; Piletsky, Sergey

2016-01-01

Our study involves development of fluorescent cell-based diagnostic assay as a new approach in high-throughput screening method. This highly sensitive optical assay operates similarly to e-noses and e-tongues which combine semi-specific sensors and multivariate data analysis for monitoring biochemical processes. The optical assay consists of a mixture of environmental-sensitive fluorescent dyes and human skin cells that generate fluorescence spectra patterns distinctive for particular physico-chemical and physiological conditions. Using chemometric techniques the optical signal is processed providing qualitative information about analytical characteristics of the samples. This integrated approach has been successfully applied (with sensitivity of 93% and specificity of 97%) in assessing whether particular chemical agents are irritating or not for human skin. It has several advantages compared with traditional biochemical or biological assays and can impact the new way of high-throughput screening and understanding cell activity. It also can provide reliable and reproducible method for assessing a risk of exposing people to different harmful substances, identification active compounds in toxicity screening and safety assessment of drugs, cosmetic or their specific ingredients. PMID:27653274

Fluorescence-based assay as a new screening tool for toxic chemicals.

PubMed

Moczko, Ewa; Mirkes, Evgeny M; Cáceres, César; Gorban, Alexander N; Piletsky, Sergey

2016-09-22

Our study involves development of fluorescent cell-based diagnostic assay as a new approach in high-throughput screening method. This highly sensitive optical assay operates similarly to e-noses and e-tongues which combine semi-specific sensors and multivariate data analysis for monitoring biochemical processes. The optical assay consists of a mixture of environmental-sensitive fluorescent dyes and human skin cells that generate fluorescence spectra patterns distinctive for particular physico-chemical and physiological conditions. Using chemometric techniques the optical signal is processed providing qualitative information about analytical characteristics of the samples. This integrated approach has been successfully applied (with sensitivity of 93% and specificity of 97%) in assessing whether particular chemical agents are irritating or not for human skin. It has several advantages compared with traditional biochemical or biological assays and can impact the new way of high-throughput screening and understanding cell activity. It also can provide reliable and reproducible method for assessing a risk of exposing people to different harmful substances, identification active compounds in toxicity screening and safety assessment of drugs, cosmetic or their specific ingredients.

Fluorescence-based assay as a new screening tool for toxic chemicals

NASA Astrophysics Data System (ADS)

Moczko, Ewa; Mirkes, Evgeny M.; Cáceres, César; Gorban, Alexander N.; Piletsky, Sergey

2016-09-01

Our study involves development of fluorescent cell-based diagnostic assay as a new approach in high-throughput screening method. This highly sensitive optical assay operates similarly to e-noses and e-tongues which combine semi-specific sensors and multivariate data analysis for monitoring biochemical processes. The optical assay consists of a mixture of environmental-sensitive fluorescent dyes and human skin cells that generate fluorescence spectra patterns distinctive for particular physico-chemical and physiological conditions. Using chemometric techniques the optical signal is processed providing qualitative information about analytical characteristics of the samples. This integrated approach has been successfully applied (with sensitivity of 93% and specificity of 97%) in assessing whether particular chemical agents are irritating or not for human skin. It has several advantages compared with traditional biochemical or biological assays and can impact the new way of high-throughput screening and understanding cell activity. It also can provide reliable and reproducible method for assessing a risk of exposing people to different harmful substances, identification active compounds in toxicity screening and safety assessment of drugs, cosmetic or their specific ingredients.

An investigation of new toxicity test method performance in validation studies: 1. Toxicity test methods that have predictive capacity no greater than chance.

PubMed

Bruner, L H; Carr, G J; Harbell, J W; Curren, R D

2002-06-01

An approach commonly used to measure new toxicity test method (NTM) performance in validation studies is to divide toxicity results into positive and negative classifications, and the identify true positive (TP), true negative (TN), false positive (FP) and false negative (FN) results. After this step is completed, the contingent probability statistics (CPS), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) are calculated. Although these statistics are widely used and often the only statistics used to assess the performance of toxicity test methods, there is little specific guidance in the validation literature on what values for these statistics indicate adequate performance. The purpose of this study was to begin developing data-based answers to this question by characterizing the CPS obtained from an NTM whose data have a completely random association with a reference test method (RTM). Determining the CPS of this worst-case scenario is useful because it provides a lower baseline from which the performance of an NTM can be judged in future validation studies. It also provides an indication of relationships in the CPS that help identify random or near-random relationships in the data. The results from this study of randomly associated tests show that the values obtained for the statistics vary significantly depending on the cut-offs chosen, that high values can be obtained for individual statistics, and that the different measures cannot be considered independently when evaluating the performance of an NTM. When the association between results of an NTM and RTM is random the sum of the complementary pairs of statistics (sensitivity + specificity, NPV + PPV) is approximately 1, and the prevalence (i.e., the proportion of toxic chemicals in the population of chemicals) and PPV are equal. Given that combinations of high sensitivity-low specificity or low specificity-high sensitivity (i.e., the sum of the sensitivity and specificity equal to approximately 1) indicate lack of predictive capacity, an NTM having these performance characteristics should be considered no better for predicting toxicity than by chance alone.

A quartz-based micro catalytic methane sensor by high resolution screen printing

NASA Astrophysics Data System (ADS)

Lu, Wenshuai; Jing, Gaoshan; Bian, Xiaomeng; Yu, Hongyan; Cui, Tianhong

2016-02-01

A micro catalytic methane sensor was proposed and fabricated on a bulk fused quartz substrate using a high resolution screen printing technique for the first time, with reduced power consumption and optimized sensitivity. The sensor was designed by the finite element method and quartz was chosen as the substrate material and alumina support with optimized dimensions. Fabrication of the sensor consisted of two MEMS processes, lift-off and high resolution screen printing, with the advantages of high yield and uniformity. When the sensor’s regional working temperature changes from 250 °C to 470 °C, its sensitivity increases, as well as the power consumption. The highest sensitivity can reach 1.52 mV/% CH4. A temperature of 300 °C was chosen as the optimized working temperature, and the sensor’s sensitivity, power consumption, nonlinearity and response time are 0.77 mV/% CH4, 415 mW, 2.6%, and 35 s, respectively. This simple, but highly uniform fabrication process and the reliable performance of this sensor may lead to wide applications for methane detection.

High-sensitivity assay for monitoring ESR1 mutations in circulating cell-free DNA of breast cancer patients receiving endocrine therapy.

PubMed

Lupini, Laura; Moretti, Anna; Bassi, Cristian; Schirone, Alessio; Pedriali, Massimo; Querzoli, Patrizia; Roncarati, Roberta; Frassoldati, Antonio; Negrini, Massimo

2018-03-12

Approximately 70% of breast cancers (BCs) express estrogen receptor alpha (ERα) and are treated with endocrine therapy. However, the effectiveness of this therapy is limited by innate or acquired resistance in approximately one-third of patients. Activating mutations in the ESR1 gene that encodes ERα promote critical resistance mechanisms. Here, we developed a high sensitivity approach based on enhanced-ice-COLD-PCR for detecting ESR1 mutations. The method produced an enrichment up to 100-fold and allowed the unambiguous detection of ESR1 mutations even when they consisted of only 0.01% of the total ESR1 allelic fraction. After COLD-PCR enrichment, methods based on next-generation sequencing or droplet-digital PCR were employed to detect and quantify ESR1 mutations. We applied the method to detect ESR1 mutations in circulating free DNA from the plasma of 56 patients with metastatic ER-positive BC. Fifteen of these patients were found to have ESR1 mutations at codons 536-538. This study demonstrates the utility of the enhanced-ice-COLD-PCR approach for simplifying and improving the detection of ESR1 tumor mutations in liquid biopsies. Because of its high sensitivity, the approach may potentially be applicable to patients with non-metastatic disease.

Highly Sensitive Naked-Eye Assay for Enterovirus 71 Detection Based on Catalytic Nanoparticle Aggregation and Immunomagnetic Amplification.

PubMed

Xiong, Ling-Hong; He, Xuewen; Xia, Junjie; Ma, Hanwu; Yang, Fan; Zhang, Qian; Huang, Dana; Chen, Long; Wu, Chunli; Zhang, Xiaomin; Zhao, Zheng; Wan, Chengsong; Zhang, Renli; Cheng, Jinquan

2017-05-03

Development of sensitive, convenient, and cost-effective virus detection product is of great significance to meet the growing demand of clinical diagnosis at the early stage of virus infection. Herein, a naked-eye readout of immunoassay by means of virion bridged catalase-mediated in situ reduction of gold ions and growth of nanoparticles, has been successfully proposed for rapid visual detection of Enterovirus 71 (EV71). Through tailoring the morphologies of the produced gold nanoparticles (GNPs) varying between dispersion and aggregation, a distinguishing color changing was ready for observation. This colorimetric detection assay, by further orchestrating the efficient magnetic enrichment and the high catalytic activity of enzyme, is managed to realize highly sensitive detection of EV71 virions with the limit of detection (LOD) down to 0.65 ng/mL. Our proposed method showed a much lower LOD value than the commercial ELISA for EV71 virion detection. Comparing to the current clinical gold standard polymerase chain reaction (PCR) method, our strategy provided the same diagnostic outcomes after testing real clinical samples. Besides, this strategy has no need of complicated sample pretreatment or expensive instruments. Our presented naked-eye immunoassay method holds a promising prospect for the early detection of virus-infectious disease especially in resource-constrained settings.

Validation of a high-throughput real-time polymerase chain reaction assay for the detection of capripoxviral DNA.

PubMed

Stubbs, Samuel; Oura, Chris A L; Henstock, Mark; Bowden, Timothy R; King, Donald P; Tuppurainen, Eeva S M

2012-02-01

Capripoxviruses, which are endemic in much of Africa and Asia, are the aetiological agents of economically devastating poxviral diseases in cattle, sheep and goats. The aim of this study was to validate a high-throughput real-time PCR assay for routine diagnostic use in a capripoxvirus reference laboratory. The performance of two previously published real-time PCR methods were compared using commercially available reagents including the amplification kits recommended in the original publication. Furthermore, both manual and robotic extraction methods used to prepare template nucleic acid were evaluated using samples collected from experimentally infected animals. The optimised assay had an analytical sensitivity of at least 63 target DNA copies per reaction, displayed a greater diagnostic sensitivity compared to conventional gel-based PCR, detected capripoxviruses isolated from outbreaks around the world and did not amplify DNA from related viruses in the genera Orthopoxvirus or Parapoxvirus. The high-throughput robotic DNA extraction procedure did not adversely affect the sensitivity of the assay compared to manual preparation of PCR templates. This laboratory-based assay provides a rapid and robust method to detect capripoxviruses following suspicion of disease in endemic or disease-free countries. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

Highly sensitive electrochemical detection of human telomerase activity based on bio-barcode method.

PubMed

Li, Ying; Liu, Bangwei; Li, Xia; Wei, Qingli

2010-07-15

In the present study, an electrochemical method for highly sensitive detection of human telomerase activity was developed based on bio-barcode amplification assay. Telomerase was extracted from HeLa cells, then the extract was mixed with telomerase substrate (TS) primer to perform extension reaction. The extension product was hybridized with the capture DNA immobilized on the Au electrode and then reacted with the signal DNA on Au nanoparticles to form a sandwich hybridization mode. Electrochemical signals were generated by chronocoulometric interrogation of [Ru(NH(3))(6)](3+) that quantitatively binds to the DNA on Au nanoparticles via electrostatic interaction. This method can detect the telomerase activity from as little as 10 cultured cancer cells without the polymerase chain reaction (PCR) amplification of telomerase extension product. Copyright (c) 2010 Elsevier B.V. All rights reserved.

High sensitivity rotation sensing based on tunable asymmetrical double-ring structure

NASA Astrophysics Data System (ADS)

Gu, Hong; Liu, Xiaoqing

2017-05-01

A very high sensitivity rotation sensor comprising a tunable asymmetrical double-ring structure (TADRS) coupled by a 3 × 3 coupler is presented. The phase difference caused by the TADRS between the counter-propagating waves is derived and discussed. At the resonant frequency, the phase shift difference has the maximum value when the light power in one cavity is amplified about 1.85 times while attenuated 79% in another. The maximum sensitivity of the TADRS sensor is two times larger than that of a single-ring structure. An experimental system is designed to verify the theoretical results and introduce the method of demodulation. The rotation sensor based on TADRS can enhance the sensitivity of the detection of the angular velocity by more than three orders of magnitude.

Manufacturing Methods and Technology Program Accomplishments

DTIC Science & Technology

1980-10-01

573,74,77.78,4139 AppI of Radar to Ballistic ACC Test of Amo (ARBAT) 43 574 4162 Automated Line for Melt-Pour Process of High Explosives 44 571,72 4171 Investigation...Sensitivity Criteria 49 576 4288 Explosive Safe Separation and Sensitivity Criteria 50 577 4288 Explosive Safe Separation and Sensitivity Sriteria 51...1 ANICIPATE. BEN(EPITS ACTUAL BENE’ITS PRO3ECT NUMBER $ SAVINGS OTHER SAVINGS OTHER REMARKS 5 73 1139 REDUCED EXPLOSIVE HAZARD TWO MACHINES WERE

Prediction of High Incidence of Dengue in the Philippines

PubMed Central

Buczak, Anna L.; Baugher, Benjamin; Babin, Steven M.; Ramac-Thomas, Liane C.; Guven, Erhan; Elbert, Yevgeniy; Koshute, Phillip T.; Velasco, John Mark S.; Roque, Vito G.; Tayag, Enrique A.; Yoon, In-Kyu; Lewis, Sheri H.

2014-01-01

Background Accurate prediction of dengue incidence levels weeks in advance of an outbreak may reduce the morbidity and mortality associated with this neglected disease. Therefore, models were developed to predict high and low dengue incidence in order to provide timely forewarnings in the Philippines. Methods Model inputs were chosen based on studies indicating variables that may impact dengue incidence. The method first uses Fuzzy Association Rule Mining techniques to extract association rules from these historical epidemiological, environmental, and socio-economic data, as well as climate data indicating future weather patterns. Selection criteria were used to choose a subset of these rules for a classifier, thereby generating a Prediction Model. The models predicted high or low incidence of dengue in a Philippines province four weeks in advance. The threshold between high and low was determined relative to historical incidence data. Principal Findings Model accuracy is described by Positive Predictive Value (PPV), Negative Predictive Value (NPV), Sensitivity, and Specificity computed on test data not previously used to develop the model. Selecting a model using the F0.5 measure, which gives PPV more importance than Sensitivity, gave these results: PPV = 0.780, NPV = 0.938, Sensitivity = 0.547, Specificity = 0.978. Using the F3 measure, which gives Sensitivity more importance than PPV, the selected model had PPV = 0.778, NPV = 0.948, Sensitivity = 0.627, Specificity = 0.974. The decision as to which model has greater utility depends on how the predictions will be used in a particular situation. Conclusions This method builds prediction models for future dengue incidence in the Philippines and is capable of being modified for use in different situations; for diseases other than dengue; and for regions beyond the Philippines. The Philippines dengue prediction models predicted high or low incidence of dengue four weeks in advance of an outbreak with high accuracy, as measured by PPV, NPV, Sensitivity, and Specificity. PMID:24722434

Structure-matched Phthalocyanine Ion Pair as a Red-emitting Fluorescent Optical Probe for the Analysis of Sodium Dodecylbenzenesulfonate with High Specificity and Sensitivity.

PubMed

Yu, Fei; Guo, Menglin; Deng, Yabin; Lu, Yin; Chen, Lin; Huang, Ping; Li, Donghui

2016-01-01

We have found that a positively charged cationic copper phthalocyanine, Alcian blue (Alcian blue 8GX), can efficiently quench the fluorescence of an oppositely charged red fluorescent phthalocyanine compound with a matched molecular structure, tetrasulfonated aluminum phthalocyanine (AlS4Pc), because of the formation of an ion pair complex (AlS4Pc-Alcian blue 8GX) that exhibits almost no fluorescence. An investigation was carried out on the fluorescence recovery of AlS4Pc-Alcian blue 8GX caused by a series of anionic surfactants containing a sulfonic group (sodium dodecylbenzenesulfonate (SDBS), sodium lauryl sulfate (SLS), and sodium dodecyl sulfate (SDS)). The results showed that SDBS exhibited a significant response, and the highest sensitivity among the surfactants. Due to its high efficiency of fluorescence quenching and the high level of fluorescence recovery, direct observes can even be performed by the naked eye. The results revealed that the Alcian blue 8GX-AlS4Pc ion-pair complex fluorescent probe only responded to SDBS in the low-concentration range. Based on the new founding, this study proposed a novel principle and method of fluorescence enhancement to specifically measure the concentration of SDBS, thereby achieving a highly sensitive and highly specific determination of SDBS. Under the optimal conditions, the fluorescence intensity (I(f)) of the system and the concentration of SDBS in the range of 1 × 10(-7) - 1 × 10(-5) mol/dm(3) exhibited a good linear relationship. This method is highly sensitive, and the operation is simple and rapid. It had been applied for the quantitative analysis of SDBS in environmental water, while achieving satisfactory results compared with those of the standard method. This study developed a new application of the fluorescent phthalocyanine compounds used as molecular probes in analytical sciences.

CON4EI: Short Time Exposure (STE) test method for hazard identification and labelling of eye irritating chemicals.

PubMed

Adriaens, E; Willoughby, J A; Meyer, B R; Blakeman, L C; Alépée, N; Fochtman, P; Guest, R; Kandarova, H; Verstraelen, S; Van Rompay, A R

2018-06-01

Assessment of ocular irritancy is an international regulatory requirement in the safety evaluation of industrial and consumer products. Although many in vitro ocular irritation assays exist, alone they are incapable of fully categorizing chemicals. Therefore, the CEFIC-LRI-AIMT6-VITO CON4EI consortium was developed to assess the reliability of eight in vitro test methods and establish an optimal tiered-testing strategy. One assay selected was the Short Time Exposure (STE) assay. This assay measures the viability of SIRC rabbit corneal cells after 5min exposure to 5% and 0.05% solutions of test material, and is capable of categorizing of Category 1 and No Category chemicals. The accuracy of the STE test method to identify Cat 1 chemicals was 61.3% with 23.7% sensitivity and 95.2% specificity. If non-soluble chemicals and unqualified results were excluded, the performance to identify Cat 1 chemicals remained similar (accuracy 62.2% with 22.7% sensitivity and 100% specificity). The accuracy of the STE test method to identify No Cat chemicals was 72.5% with 66.2% sensitivity and 100% specificity. Excluding highly volatile chemicals, non-surfactant solids and non-qualified results resulted in an important improvement of the performance of the STE test method (accuracy 96.2% with 81.8% sensitivity and 100% specificity). Furthermore, it seems that solids are more difficult to test in the STE, 71.4% of the solids resulted in unqualified results (solubility issues and/or high variation between independent runs) whereas for liquids 13.2% of the results were not qualified, supporting the restriction of the test method regarding the testing of solids. Copyright © 2017. Published by Elsevier Ltd.

Diagnostic algorithm for detection of targetable driver mutations in lung adenocarcinomas: Comprehensive analyses of 205 cases with immunohistochemistry, real-time PCR and fluorescence in situ hybridization methods.

PubMed

Kao, Hua-Lin; Yeh, Yi-Chen; Lin, Chin-Hsuan; Hsu, Wei-Fang; Hsieh, Wen-Yu; Ho, Hsiang-Ling; Chou, Teh-Ying

2016-11-01

Analysis of the targetable driver mutations is now recommended in all patients with advanced lung adenocarcinoma. Molecular-based methods are usually adopted, however, along with the implementation of highly sensitive and/or mutation-specific antibodies, immunohistochemistry (IHC) has been considered an alternative method for identifying driver mutations in lung adenocarcinomas. A total of 205 lung adenocarcinomas were examined for EGFR mutations and ALK and ROS1 rearrangements using real-time PCR, fluorescence in situ hybridization (FISH) and IHC in parallel. The performance of different commercially available IHC antibody clones toward targetable driver mutations was evaluated. The association between these driver mutations and clinicopathological characteristics was also analyzed. In 205 cases we studied, 58.5% were found to harbor EGFR mutations, 6.3% ALK rearrangements and 1.0% ROS1 rearrangements. Compared to molecular-based methods, IHC of EGFR mutations showed an excellent specificity but the sensitivity is suboptimal, while IHC of ALK and ROS1 rearrangements demonstrated high sensitivity and specificity. No significant difference regarding the performance of different antibody clones toward these driver mutations was observed, except that clone SP125 showed a higher sensitivity than 43B2 in the detection of p.L858R of EGFR. In circumstances such as poor quality of nucleic acids or low content of tumor cells, IHC of EGFR mutation-specific antibodies could be used as an alternative method. Patients negative for EGFR mutations are subjected to further analysis on ALK and ROS1 rearrangements using IHC methods. Herein, we proposed a lung adenocarcinoma testing algorithm for the application of IHC in therapeutic diagnosis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Ultra-sensitive magnetic microscopy with an optically pumped magnetometer

DOE PAGES

Kim, Young Jin; Savukov, Igor Mykhaylovich

2016-04-22

Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized devicemore » can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). Additionally, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.« less

Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer

NASA Astrophysics Data System (ADS)

Kim, Young Jin; Savukov, Igor

2016-04-01

Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

Ultra-sensitive magnetic microscopy with an optically pumped magnetometer

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

Kim, Young Jin; Savukov, Igor Mykhaylovich

Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized devicemore » can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). Additionally, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.« less

High-performance liquid chromatography with fluorescence detection for the rapid analysis of pheophytins and pyropheophytins in virgin olive oil.

PubMed

Li, Xueqi; Woodman, Michael; Wang, Selina C

2015-08-01

Pheophytins and pyropheophytin are degradation products of chlorophyll pigments, and their ratios can be used as a sensitive indicator of stress during the manufacturing and storage of olive oil. They increase over time depending on the storage condition and if the oil is exposed to heat treatments during the refining process. The traditional analysis method includes solvent- and time-consuming steps of solid-phase extraction followed by analysis by high-performance liquid chromatography with ultraviolet detection. We developed an improved dilute/fluorescence method where multi-step sample preparation was replaced by a simple isopropanol dilution before the high-performance liquid chromatography injection. A quaternary solvent gradient method was used to include a fourth strong solvent wash on a quaternary gradient pump, which avoided the need to premix any solvents and greatly reduced the oil residues on the column from previous analysis. This new method not only reduces analysis cost and time but shows reliability, repeatability, and improved sensitivity, especially important for low-level samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Utility of Hantzsch reaction for development of highly sensitive spectrofluorimetric method for determination of alfuzosin and terazosin in bulk, dosage forms and human plasma.

PubMed

Hammad, Mohamed A; Omar, Mahmoud A; Salman, Baher I

2017-09-01

A highly sensitive, cheap, simple and accurate spectrofluorimetric method has been developed and validated for the determination of alfuzosin hydrochloride and terazosin hydrochloride in their pharmaceutical dosage forms and in human plasma. The developed method is based on the reaction of the primary amine moiety in the studied drugs with acetylacetone and formaldehyde according to the Hantzsch reaction, producing yellow fluorescent products that can be measured spectrofluorimetrically at 480 nm after excitation at 415 nm. Different experimental parameters affecting the development and stability of the reaction products were carefully studied and optimized. The fluorescence-concentration plots of alfuzosin and terazosin were rectilinear over a concentration range of 70-900 ng ml -1 , with quantitation limits 27.1 and 32.2 ng ml -1 for alfuzosin and terazosin, respectively. The proposed method was validated according to ICH guidelines and successfully applied to the analysis of the investigated drugs in dosage forms, content uniformity test and spiked human plasma with high accuracy. Copyright © 2017 John Wiley & Sons, Ltd.

A comparison of sorptive extraction techniques coupled to a new quantitative, sensitive, high throughput GC-MS/MS method for methoxypyrazine analysis in wine.

PubMed

Hjelmeland, Anna K; Wylie, Philip L; Ebeler, Susan E

2016-02-01

Methoxypyrazines are volatile compounds found in plants, microbes, and insects that have potent vegetal and earthy aromas. With sensory detection thresholds in the low ng L(-1) range, modest concentrations of these compounds can profoundly impact the aroma quality of foods and beverages, and high levels can lead to consumer rejection. The wine industry routinely analyzes the most prevalent methoxypyrazine, 2-isobutyl-3-methoxypyrazine (IBMP), to aid in harvest decisions, since concentrations decrease during berry ripening. In addition to IBMP, three other methoxypyrazines IPMP (2-isopropyl-3-methoxypyrazine), SBMP (2-sec-butyl-3-methoxypyrazine), and EMP (2-ethyl-3-methoxypyrazine) have been identified in grapes and/or wine and can impact aroma quality. Despite their routine analysis in the wine industry (mostly IBMP), accurate methoxypyrazine quantitation is hindered by two major challenges: sensitivity and resolution. With extremely low sensory detection thresholds (~8-15 ng L(-1) in wine for IBMP), highly sensitive analytical methods to quantify methoxypyrazines at trace levels are necessary. Here we were able to achieve resolution of IBMP as well as IPMP, EMP, and SBMP from co-eluting compounds using one-dimensional chromatography coupled to positive chemical ionization tandem mass spectrometry. Three extraction techniques HS-SPME (headspace-solid phase microextraction), SBSE (stirbar sorptive extraction), and HSSE (headspace sorptive extraction) were validated and compared. A 30 min extraction time was used for HS-SPME and SBSE extraction techniques, while 120 min was necessary to achieve sufficient sensitivity for HSSE extractions. All extraction methods have limits of quantitation (LOQ) at or below 1 ng L(-1) for all four methoxypyrazines analyzed, i.e., LOQ's at or below reported sensory detection limits in wine. The method is high throughput, with resolution of all compounds possible with a relatively rapid 27 min GC oven program. Copyright © 2015 Elsevier B.V. All rights reserved.

A biomolecular detection method based on charge pumping in a nanogap embedded field-effect-transistor biosensor

NASA Astrophysics Data System (ADS)

Kim, Sungho; Ahn, Jae-Hyuk; Park, Tae Jung; Lee, Sang Yup; Choi, Yang-Kyu

2009-06-01

A unique direct electrical detection method of biomolecules, charge pumping, was demonstrated using a nanogap embedded field-effect-transistor (FET). With aid of a charge pumping method, sensitivity can fall below the 1 ng/ml concentration regime in antigen-antibody binding of an avian influenza case. Biomolecules immobilized in the nanogap are mainly responsible for the acute changes of the interface trap density due to modulation of the energy level of the trap. This finding is supported by a numerical simulation. The proposed detection method for biomolecules using a nanogap embedded FET represents a foundation for a chip-based biosensor capable of high sensitivity.

Compliance and stress sensitivity of spur gear teeth

NASA Technical Reports Server (NTRS)

Cornell, R. W.

1983-01-01

The magnitude and variation of tooth pair compliance with load position affects the dynamics and loading significantly, and the tooth root stressing per load varies significantly with load position. Therefore, the recently developed time history, interactive, closed form solution for the dynamic tooth loads for both low and high contact ratio spur gears was expanded to include improved and simplified methods for calculating the compliance and stress sensitivity for three involute tooth forms as a function of load position. The compliance analysis has an improved fillet/foundation. The stress sensitivity analysis is a modified version of the Heywood method but with an improvement in the magnitude and location of the peak stress in the fillet. These improved compliance and stress sensitivity analyses are presented along with their evaluation using test, finite element, and analytic transformation results, which showed good agreement.

Rapid Magnetic Nanobiosensor for the detection of Serratia marcescen

NASA Astrophysics Data System (ADS)

Aljabali, Alaa A. A.; Hussein, Emad; Aljumaili, Omar; Zoubi, Mazhar Al; Altrad, Bahaa; Albatayneh, Khaled; Al-razaq, Mutaz A. Abd

2018-02-01

The development of rapid, sensitive, accurate and reliable bacterial detection methods are of keen interest to ensure food safety and hospital security. Therefore, the development of a fast, specific, low-cost and trusted methods is in high demand. Magnetic nanoparticles with their unique material properties have been utilized as a tool for pathogen detection. Here, we present a novel iron oxide nanoparticles labeled with specific targeting antibodies to improve specificity and extend the use of nanoparticles as nanosensors. The results indicated that antibody labeled iron oxide platform that binds specifically to Serriata marcescenst in a straightforward method is very specific and sensitive. The system is capable of rapid and specific detection of various clinically relevant bacterial species, with sensitivity down to single bacteria. The generic platform could be used to identify pathogens for a variety of applications rapidly.

Development of a sensitive method for the determination of acrylamide in coffee using high-performance liquid chromatography coupled to a hybrid quadrupole Orbitrap mass spectrometer.

PubMed

Pugajeva, Iveta; Jaunbergs, Janis; Bartkevics, Vadims

2015-01-01

The emerging trend towards high-resolution mass spectrometry (MS) alternatives was evaluated by the application of Orbitrap MS for the determination of acrylamide in coffee samples. The high resolving power of the Orbitrap MS provided the high selectivity and sensitivity that enabled quantitative analysis of acrylamide in complex matrices, such as coffee. Several sample preparation methods and scanning modes of the MS (full MS, t-SIM, t-MS2) were assessed in order to optimise parameters of the analytical method. The final procedure involved the extraction of acrylamide with acetonitrile, solid-phase extraction with dispersive primary secondary amine (PSA) and amino columns, and the detection by ultra-performance liquid chromatography coupled to a hybrid quadrupole-Orbitrap MS (HPLC-Q-Orbitrap) operated in targeted MS2 scanning mode. The repeatability of the method at the lowest calibration level (10 μg kg(-1)), expressed as relative standard deviation, was 7.8% and the average recovery of acrylamide was 111%. The proposed method was applied to the determination of acrylamide in 22 samples of roasted coffee obtained from the Latvian retail market. Acrylamide concentration in coffee samples was in the range of 166-503 μg kg(-1).

Highly sensitive quantification for human plasma-targeted metabolomics using an amine derivatization reagent.

PubMed

Arashida, Naoko; Nishimoto, Rumi; Harada, Masashi; Shimbo, Kazutaka; Yamada, Naoyuki

2017-02-15

Amino acids and their related metabolites play important roles in various physiological processes and have consequently become biomarkers for diseases. However, accurate quantification methods have only been established for major compounds, such as amino acids and a limited number of target metabolites. We previously reported a highly sensitive high-throughput method for the simultaneous quantification of amines using 3-aminopyridyl-N-succinimidyl carbamate as a derivatization reagent combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Herein, we report the successful development of a practical and accurate LC-MS/MS method to analyze low concentrations of 40 physiological amines in 19 min. Thirty-five of these amines showed good linearity, limits of quantification, accuracy, precision, and recovery characteristics in plasma, with scheduled selected reaction monitoring acquisitions. Plasma samples from 10 healthy volunteers were evaluated using our newly developed method. The results revealed that 27 amines were detected in one of the samples, and that 24 of these compounds could be quantified. Notably, this new method successfully quantified metabolites with high accuracy across three orders of magnitude, with lowest and highest averaged concentrations of 31.7 nM (for spermine) and 18.3 μM (for α-aminobutyric acid), respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

[High-sensitive detection of multiple allergenic proteins in infant food with high-resolution mass spectrometry].

PubMed

Wu, Ci; Chen, Xi; Liu, Jianhui; Zhang, Xiaolin; Xue, Weifeng; Liang, Zhen; Liu, Mengyao; Cui, Yan; Huang, Daliang; Zhang, Lihua

2017-10-08

A novel method of the simultaneous detection of multiple kinds of allergenic proteins in infant food with parallel reaction monitoring (PRM) mode using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established. In this method, unique peptides with good stability and high sensibility were used to quantify the corresponding allergenic proteins. Furthermore, multiple kinds of allergenic proteins are inspected simultaneously with high sensitivity. In addition, such method was successfully used for the detection of multiple allergenic proteins in infant food. As for the sample preparation for infant food, compared with the traditional acetone precipitation strategy, the protein extraction efficiency and capacity of resisting disturbance are both higher with in-situ filter-aided sample pretreatment (i-FASP) method. All allergenic proteins gave a good linear response with the correlation coefficients ( R 2 ) ≥ 0.99, and the largest concentration range of the allergenic proteins could be four orders of magnitude, and the lowest detection limit was 0.028 mg/L, which was better than that reported in references. Finally, the method was conveniently used to detect the allergens from four imported infant food real samples. All the results demonstrate that this novel strategy is of great significance for providing a rapid and reliable analytical technique for allergen proteomics.

Assisted inhibition effect of acetylcholinesterase with n-octylphosphonic acid and application in high sensitive detection of organophosphorous pesticides by matrix-assisted laser desorption/ionization Fourier transform mass spectrometry.

PubMed

Cai, Tingting; Zhang, Li; Wang, Haoyang; Zhang, Jing; Guo, Yinlong

2011-11-14

A simple and practical approach to improve the sensitivity of acetylcholinesterase (AChE)-inhibited method has been developed for monitoring organophosphorous (OP) pesticide residues. In this work, matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) was used to detect AChE activity. Due to its good salt-tolerance and low sample consumption, MALDI-FTMS facilitates rapid and high-throughput screening of OP pesticides. Here we describe a new method to obtain low detection limits via employing external reagents. Among candidate compounds, n-octylphosphonic acid (n-Octyl-PA) displays assistant effect to enhance AChE inhibition by OP pesticides. In presence of n-Octyl-PA, the percentages of AChE inhibition still kept correlation with OP pesticide concentrations. The detection limits were improved significantly even by 10(2)-10(3) folds in comparison with conventional enzyme-inhibited methods. Different detection limits of OP pesticides with different toxicities were as low as 0.005 μg L(-1) for high toxic pesticides and 0.05 μg L(-1) for low toxic pesticides. Besides, the reliability of results from this method to analyze cowpea samples had been demonstrated by liquid-chromatography tandem mass spectrometry (LC-MS/MS). The application of this commercial available assistant agent shows great promise to detect OP compounds in complicated biological matrix and broadens the mind for high sensitivity detection of OP pesticide residues in agricultural products. Copyright © 2011 Elsevier B.V. All rights reserved.

Sensitivities to Early Exchange in Synchronous Computer-Supported Collaborative Learning (CSCL) Groups

ERIC Educational Resources Information Center

Kapur, Manu; Voiklis, John; Kinzer, Charles K.

2008-01-01

This study reports the impact of high sensitivity to early exchange in 11th-grade, CSCL triads solving well- and ill-structured problems in Newtonian Kinematics. A mixed-method analysis of the evolution of participation inequity (PI) in group discussions suggested that participation levels tended to get locked-in relatively early on in the…

Study on thin wideband applicator for detecting blood characteristics in human body

NASA Astrophysics Data System (ADS)

Bamba, Kazuki; Kuki, Takao; Nikawa, Yoshio

2016-11-01

Preventive care as well as early detection method and monitoring technique for diseases are highly attracted attention to increase quality of life. Noninvasive measurement method for blood characteristics in body is expected by patients with kidney dysfunction. Complex permittivity of blood is changed a few present at 6GHz. This change is caused by the change of water and albumin contents in blood. In this study, to detect blood characteristics in human body, experiments with phantom model has been performed using thin wideband applicator for examining microwave transmission up to 6GHz. The thin wideband applicator has advantages for detecting living body information in detail. The thin wideband applicator is designed based on Antipodal Vivaldi Antenna and is not required any balun and is very easy handling. Using developed Antipodal Vivaldi Antenna, transmission coefficient can be obtained as a function of thickness of phantom model with high sensitivity. Using this method, highly sensitive sensor for obtaining characteristics of blood in body can be developed.

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

Gilbert, Andrew J.; Miller, Brian W.; Robinson, Sean M.

Imaging technology is generally considered too invasive for arms control inspections due to the concern that it cannot properly secure sensitive features of the inspected item. However, this same sensitive information, which could include direct information on the form and function of the items under inspection, could be used for robust arms control inspections. The single-pixel X-ray imager (SPXI) is introduced as a method to make such inspections, capturing the salient spatial information of an object in a secure manner while never forming an actual image. The method is built on the theory of compressive sensing and the single pixelmore » optical camera. The performance of the system is quantified here using simulated inspections of simple objects. Measures of the robustness and security of the method are introduced and used to determine how such an inspection would be made which can maintain high robustness and security. In particular, it is found that an inspection with low noise (<1%) and high undersampling (>256×) exhibits high robustness and security.« less

Synthesis of ZnO nanopencils using wet chemical method and its investigation as LPG sensor

NASA Astrophysics Data System (ADS)

Shimpi, Navinchandra G.; Jain, Shilpa; Karmakar, Narayan; Shah, Akshara; Kothari, D. C.; Mishra, Satyendra

2016-12-01

ZnO nanopencils (NPCs) were prepared by a novel wet chemical process, using triethanolamine (TEA) as a mild base, which is relatively simple and cost effective method as compared to hydrothermal method. ZnO NPCs were characterized using powder X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy in mid-IR and far-IR regions, X-ray Photoelectron Spectroscopy (XPS), UV-vis (UV-vis) absorption spectroscopy, room temperature Photoluminescence (PL) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). ZnO NPCs obtained, were highly pure, uniform and monodispersed.XRD pattern indicated hexagonal unit cell structure with preferred orientation along the c-axis. Sensing behaviour of ZnO NPCs was studied towards Liquefied Petroleum Gas (LPG) at different operating temperatures. The study shows that ZnO NPCs were most sensitive and promising candidate for detection of LPG at 250 °C with gas sensitivity > 60%. The high response towards LPG is due to high surface area of ZnO NPCs and their parallel alignment.

Improving LC-MS sensitivity through increases in chromatographic performance: comparisons of UPLC-ES/MS/MS to HPLC-ES/MS/MS.

PubMed

Churchwell, Mona I; Twaddle, Nathan C; Meeker, Larry R; Doerge, Daniel R

2005-10-25

Recent technological advances have made available reverse phase chromatographic media with a 1.7 microm particle size along with a liquid handling system that can operate such columns at much higher pressures. This technology, termed ultra performance liquid chromatography (UPLC), offers significant theoretical advantages in resolution, speed, and sensitivity for analytical determinations, particularly when coupled with mass spectrometers capable of high-speed acquisitions. This paper explores the differences in LC-MS performance by conducting a side-by-side comparison of UPLC for several methods previously optimized for HPLC-based separation and quantification of multiple analytes with maximum throughput. In general, UPLC produced significant improvements in method sensitivity, speed, and resolution. Sensitivity increases with UPLC, which were found to be analyte-dependent, were as large as 10-fold and improvements in method speed were as large as 5-fold under conditions of comparable peak separations. Improvements in chromatographic resolution with UPLC were apparent from generally narrower peak widths and from a separation of diastereomers not possible using HPLC. Overall, the improvements in LC-MS method sensitivity, speed, and resolution provided by UPLC show that further advances can be made in analytical methodology to add significant value to hypothesis-driven research.

Detectors for the gamma-ray resonant absorption (GRA) method of explosives detection in cargo: a comparative study

NASA Astrophysics Data System (ADS)

Vartsky, David; Goldberg, Mark B.; Engler, Gideon; Shor, Asher; Goldschmidt, Aharon; Feldman, Gennady; Bar, Doron; Orion, Itzhak; Wielopolski, Lucian

2004-01-01

Gamma-Ray Resonant Absorption (GRA) is an automatic-decision radiographic screening technique that combines high radiation penetration with very good sensitivity and specificity to nitrogenous explosives. The method is particularly well-suited to inspection of large, massive objects (since the resonant γ-ray probe is at 9.17 MeV) such as aviation and marine containers, heavy vehicles and railroad cars. Two kinds of γ-ray detectors have been employed to date in GRA systems: 1) Resonant-response nitrogen-rich liquid scintillators and 2) BGO detectors. This paper analyses and compares the response of these detector-types to the resonant radiation, in terms of single-pixel figures of merit. The latter are sensitive not only to detector response, but also to accelerator-beam quality, via the properties of the nuclear reaction that produces the resonant-γ-rays. Generally, resonant detectors give rise to much higher nitrogen-contrast sensitivity in the radiographic image than their non-resonant detector counterparts and furthermore, do not require proton beams of high energy-resolution. By comparison, the non-resonant detectors have higher γ-detection efficiency, but their contrast sensitivity is very sensitive to the quality of the accelerator beam. Implications of these detector/accelerator characteristics for eventual GRA field systems are discussed.

A simple, sensitive and rapid isocratic reversed-phase high-performance liquid chromatography method for determination and stability study of curcumin in pharmaceutical samples

PubMed Central

Amanolahi, Farjad; Mohammadi, Ali; Kazemi Oskuee, Reza; Nassirli, Hooriyeh; Malaekeh-Nikouei, Bizhan

2017-01-01

Objective: This study was designed to develop and validate a new reversed-phase high-performance liquid chromatography (RP-HPLC) method based on Q2 (R1) International Conference on Harmonization (ICH) guideline for determination of curcumin in pharmaceutical samples. Materials and Methods: The HPLC instrument method was optimized with isocratic elution with acetonitrile: ammonium acetate (45:55, v/v, pH 3.5), C18 column (150 mm×4.6 mm×5 µm particle size) and a flow rate of 1 ml/min in ambient condition and total retention time of 17 min. The volume of injection was set at 20 µl and detection was recorded at 425 nm. The robustness of the method was examined by changing the mobile phase composition, mobile phase pH, and flow rate. Results: The method was validated with respect to precision, accuracy and linearity in a concentration range of 2-100 µg/ml. The limit of detection (LOD) and limit of quantification (LOQ) were 0.25 and 0.5 µg/ml, respectively. The percentage of recovery was 98.9 to 100.5 with relative standard deviation (RSD) < 0.638%. Conclusion: The method was found to be simple, sensitive and rapid for determination of curcumin in pharmaceutical samples and had enough sensitivity to detect degradation product of curcumin produced under photolysis and hydrolysis stress condition. PMID:29062806

A dual-wavelength overlapping resonance Rayleigh scattering method for the determination of chondroitin sulfate with nile blue sulfate

NASA Astrophysics Data System (ADS)

Cui, Zhiping; Hu, Xiaoli; Liu, Shaopu; Liu, Zhongfang

2011-12-01

A dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) method was developed to detect chondroitin sulfate (CS) with nile blue sulfate (NBS). At pH 3.0-4.0 Britton-Robinson (BR) buffer medium, CS interacted with NBS to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering (RRS), second order scattering (SOS) and frequence doubling scattering (FDS) appeared and their intensities were enhanced greatly. Their maximum wavelengths were located at 303 nm (RRS), 362 nm (RRS), 588 nm (SOS) and 350 nm (FDS), respectively. The scattering intensities of the three methods were proportional to the concentration of CS in certain ranges. The methods had high sensitivity and the detection limits were between 1.5 and 7.1 ng mL -1. The DWO-RRS method had the highest sensitivity with the detection limit being 1.5 ng mL -1. The characteristics of the spectra and optimal reaction conditions of RRS method were investigated. The effects of coexistent substances on the determination of CS were evaluated. Owing to the high sensitivity, RRS method had been applied to the determination of CS in eye drops with satisfactory results. The recovery range was between 99.4% and 104.6% and the relative standard deviation (RSD) was between 0.4% and 0.8%. In addition, the reasons for RRS enhancement were discussed and the shape of ion-association complex was characterized by atomic force microscopy (AFM).

Gold nanoparticle-sensitized quartz crystal microbalance sensor for rapid and highly selective determination of Cu(II) ions.

PubMed

Jin, Yulong; Huang, Yanyan; Liu, Guoquan; Zhao, Rui

2013-09-21

A novel quartz crystal microbalance (QCM) sensor for rapid, highly selective and sensitive detection of copper ions was developed. As a signal amplifier, gold nanoparticles (Au NPs) were self-assembled onto the surface of the sensor. A simple dip-and-dry method enabled the whole detection procedure to be accomplished within 20 min. High selectivity of the sensor towards copper ions is demonstrated by both individual and coexisting assays with interference ions. This gold nanoparticle mediated amplification allowed a detection limit down to 3.1 μM. Together with good repeatability and regeneration, the QCM sensor was also applied to the analysis of copper contamination in drinking water. This work provides a flexible method for fabricating QCM sensors for the analysis of important small molecules in environmental and biological samples.

Stimulated Raman scattering (SRS) spectroscopic OCT (Conference Presentation)

NASA Astrophysics Data System (ADS)

Robles, Francisco E.; Zhou, Kevin C.; Fischer, Martin C.; Warren, Warren S.

2017-02-01

Optical coherence tomography (OCT) enables non-invasive, high-resolution, tomographic imaging of biological tissues by leveraging principles of low coherence interferometry; however, OCT lacks molecular specificity. Spectroscopic OCT (SOCT) overcomes this limitation by providing depth-resolved spectroscopic signatures of chromophores, but SOCT has been limited to a couple of endogenous molecules, namely hemoglobin and melanin. Stimulated Raman scattering, on the other hand, can provide highly specific molecular information of many endogenous species, but lacks the spatial and spectral multiplexing capabilities of SOCT. In this work we integrate the two methods, SRS and SOCT, to enable simultaneously multiplexed spatial and spectral imaging with sensitivity to many endogenous biochemical species that play an important role in biology and medicine. The method, termed SRS-SOCT, has the potential to achieve fast, volumetric, and highly sensitive label-free molecular imaging, which would be valuable for many applications. We demonstrate the approach by imaging excised human adipose tissue and detecting the lipids' Raman signatures in the high-wavenumber region. Details of this method along with validations and results will be presented.

Statistical method evaluation for differentially methylated CpGs in base resolution next-generation DNA sequencing data.

PubMed

Zhang, Yun; Baheti, Saurabh; Sun, Zhifu

2018-05-01

High-throughput bisulfite methylation sequencing such as reduced representation bisulfite sequencing (RRBS), Agilent SureSelect Human Methyl-Seq (Methyl-seq) or whole-genome bisulfite sequencing is commonly used for base resolution methylome research. These data are represented either by the ratio of methylated cytosine versus total coverage at a CpG site or numbers of methylated and unmethylated cytosines. Multiple statistical methods can be used to detect differentially methylated CpGs (DMCs) between conditions, and these methods are often the base for the next step of differentially methylated region identification. The ratio data have a flexibility of fitting to many linear models, but the raw count data take consideration of coverage information. There is an array of options in each datatype for DMC detection; however, it is not clear which is an optimal statistical method. In this study, we systematically evaluated four statistic methods on methylation ratio data and four methods on count-based data and compared their performances with regard to type I error control, sensitivity and specificity of DMC detection and computational resource demands using real RRBS data along with simulation. Our results show that the ratio-based tests are generally more conservative (less sensitive) than the count-based tests. However, some count-based methods have high false-positive rates and should be avoided. The beta-binomial model gives a good balance between sensitivity and specificity and is preferred method. Selection of methods in different settings, signal versus noise and sample size estimation are also discussed.

Technical Note: Synchrotron-based high-energy x-ray phase sensitive microtomography for biomedical research

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

Liu, Huiqiang; Wu, Xizeng, E-mail: xwu@uabmc.edu, E-mail: tqxiao@sinap.ac.cn; Xiao, Tiqiao, E-mail: xwu@uabmc.edu, E-mail: tqxiao@sinap.ac.cn

Purpose: Propagation-based phase-contrast CT (PPCT) utilizes highly sensitive phase-contrast technology applied to x-ray microtomography. Performing phase retrieval on the acquired angular projections can enhance image contrast and enable quantitative imaging. In this work, the authors demonstrate the validity and advantages of a novel technique for high-resolution PPCT by using the generalized phase-attenuation duality (PAD) method of phase retrieval. Methods: A high-resolution angular projection data set of a fish head specimen was acquired with a monochromatic 60-keV x-ray beam. In one approach, the projection data were directly used for tomographic reconstruction. In two other approaches, the projection data were preprocessed bymore » phase retrieval based on either the linearized PAD method or the generalized PAD method. The reconstructed images from all three approaches were then compared in terms of tissue contrast-to-noise ratio and spatial resolution. Results: The authors’ experimental results demonstrated the validity of the PPCT technique based on the generalized PAD-based method. In addition, the results show that the authors’ technique is superior to the direct PPCT technique as well as the linearized PAD-based PPCT technique in terms of their relative capabilities for tissue discrimination and characterization. Conclusions: This novel PPCT technique demonstrates great potential for biomedical imaging, especially for applications that require high spatial resolution and limited radiation exposure.« less

Sensitive Quantification of Cannabinoids in Milk by Alkaline Saponification-Solid Phase Extraction Combined with Isotope Dilution UPLC-MS/MS.

PubMed

Wei, Binnian; McGuffey, James E; Blount, Benjamin C; Wang, Lanqing

2016-01-01

Maternal exposure to marijuana during the lactation period-either active or passive-has prompted concerns about transmission of cannabinoids to breastfed infants and possible subsequent adverse health consequences. Assessing these health risks requires a sensitive analytical approach that is able to quantitatively measure trace-level cannabinoids in breast milk. Here, we describe a saponification-solid phase extraction approach combined with ultra-high-pressure liquid chromatography-tandem mass spectrometry for simultaneously quantifying Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) in breast milk. We demonstrate for the first time that constraints on sensitivity can be overcome by utilizing alkaline saponification of the milk samples. After extensively optimizing the saponification procedure, the validated method exhibited limits of detections of 13, 4, and 66 pg/mL for THC, CBN, and CBD, respectively. Notably, the sensitivity achieved was significantly improved, for instance, the limits of detection for THC is at least 100-fold more sensitive compared to that previously reported in the literature. This is essential for monitoring cannabinoids in breast milk resulting from passive or nonrecent active maternal exposure. Furthermore, we simultaneously acquired multiple reaction monitoring transitions for 12 C- and 13 C-analyte isotopes. This combined analysis largely facilitated data acquisition by reducing the repetitive analysis rate for samples exceeding the linear limits of 12 C-analytes. In addition to high sensitivity and broad quantitation range, this method delivers excellent accuracy (relative error within ±10%), precision (relative standard deviation <10%), and efficient analysis. In future studies, we expect this method to play a critical role in assessing infant exposure to cannabinoids through breastfeeding.

Highly sensitive detection using microring resonator and nanopores

NASA Astrophysics Data System (ADS)

Bougot-Robin, K.; Hoste, J. W.; Le Thomas, N.; Bienstman, P.; Edel, J. B.

2016-04-01

One of the most significant challenges facing physical and biological scientists is the accurate detection and identification of single molecules in free-solution environments. The ability to perform such sensitive and selective measurements opens new avenues for a large number of applications in biological, medical and chemical analysis, where small sample volumes and low analyte concentrations are the norm. Access to information at the single or few molecules scale is rendered possible by a fine combination of recent advances in technologies. We propose a novel detection method that combines highly sensitive label-free resonant sensing obtained with high-Q microcavities and position control in nanoscale pores (nanopores). In addition to be label-free and highly sensitive, our technique is immobilization free and does not rely on surface biochemistry to bind probes on a chip. This is a significant advantage, both in term of biology uncertainties and fewer biological preparation steps. Through combination of high-Q photonic structures with translocation through nanopore at the end of a pipette, or through a solid-state membrane, we believe significant advances can be achieved in the field of biosensing. Silicon microrings are highly advantageous in term of sensitivity, multiplexing, and microfabrication and are chosen for this study. In term of nanopores, we both consider nanopore at the end of a nanopipette, with the pore being approach from the pipette with nanoprecise mechanical control. Alternatively, solid state nanopores can be fabricated through a membrane, supporting the ring. Both configuration are discussed in this paper, in term of implementation and sensitivity.

Dietary supplementation with fish oil prevents high fat diet-induced enhancement of sensitivity to the locomotor stimulating effects of cocaine in adolescent female rats

PubMed Central

Serafine, Katherine M.; Labay, Caitlin; France, Charles P.

2016-01-01

BACKGROUND Eating a diet high in fat can lead to obesity, chronic metabolic disease, and increased inflammation in both the central and peripheral nervous systems. Dietary supplements that are high in omega-3 polyunsaturated fatty acids can reduce or prevent these negative health consequences in rats. Eating high fat chow also increases the sensitivity of rats to behavioral effects of drugs acting on dopamine systems (e.g., cocaine), and this effect is greatest in adolescent females. METHODS The present experiment tested the hypothesis that dietary supplementation with fish oil prevents high fat chow induced increases in sensitivity to cocaine in adolescent female rats. Female Sprague-Dawley rats (post-natal day 25–27) ate standard laboratory chow (5.7% fat), high fat chow (34.4% fat), or high fat chow supplemented with fish oil (20% w/w). Cocaine dose dependently (1–17.8 mg/kg) increased locomotion and induced sensitization across 6 weeks of once-weekly testing in all rats; however, these effects were greatest in rats eating high fat chow. RESULTS Dietary supplementation with fish oil prevented enhanced locomotion and sensitization in rats eating high fat chow. There were no differences in inflammatory markers in plasma or the hypothalamus among dietary conditions. CONCLUSIONS These results demonstrate that dietary supplementation with fish oil can prevent high fat diet-induced sensitization to cocaine, but they fail to support the view that these effects are due to changes in proinflammatory cytokines. These data add to a growing literature on the relationship between diet and drug abuse and extend the potential health benefits of fish oil to stimulant drug abuse prevention. PMID:27242289

Identification and quantification of cardiac glycosides in blood and urine samples by HPLC/MS/MS.

PubMed

Guan, F; Ishii, A; Seno, H; Watanabe-Suzuki, K; Kumazawa, T; Suzuki, O

1999-09-15

Cardiac glycosides (CG) are of forensic importance because of their toxicity and the fact that very limited methods are available for identification of CG in biological samples. In this study, we have developed an identification and quantification method for digoxin, digitoxin, deslanoside, digoxigenin, and digitoxigenin by high-performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS). CG formed abundant [M + NH4]+ ions and much less abundant [M + H]+ ions as observed with electrospray ionization (ESI) source and ammonium formate buffer. Under mild conditions for collision-induced dissociation (CID), each [M + NH4]+ ion fragmented to produce a dominant daughter ion, which was essential to the sensitive method of selected reaction monitoring (SRM) quantification of CG achieved in this study. SRM was compared with selected ion monitoring (SIM) regarding the effects of sample matrixes on the methodology. SRM produced lower detection limits with biological samples than SIM, while both methods produced equal detection limits with CG standards. On the basis of the HPLC/MS/MS results for CG, we have proposed some generalized points for conducting sensitive SRM measurements, in view of the property of analytes as well as instrumental conditions such as the type of HPLC/MS interface and CID parameters. Analytes of which the molecular ion can produce one abundant daughter ion with high yield under CID conditions may be sensitively measured by SRM. ESI is the most soft ionization source developed so far and can afford formation of the fragile molecular ions that are necessary for sensitive SRM detection. Mild CID conditions such as low collision energy and low pressure of collision gas favor production of an abundant daughter ion that is essential to sensitive SRM detection. This knowledge may provide some guidelines for conducting sensitive SRM measurements of very low concentrations of drugs or toxicants in biological samples.

Optoelectronic method for detection of cervical intraepithelial neoplasia and cervical cancer

NASA Astrophysics Data System (ADS)

Pruski, D.; Przybylski, M.; Kędzia, W.; Kędzia, H.; Jagielska-Pruska, J.; Spaczyński, M.

2011-12-01

The optoelectronic method is one of the most promising concepts of biophysical program of the diagnostics of CIN and cervical cancer. Objectives of the work are evaluation of sensitivity and specificity of the optoelectronic method in the detection of CIN and cervical cancer. The paper shows correlation between the pNOR number and sensitivity/specificity of the optoelectronic method. The study included 293 patients with abnormal cervical cytology result and the following examinations: examination with the use of the optoelectronic method — Truscreen, colposcopic examination, and histopathologic biopsy. Specificity of the optoelectronic method for LGSIL was estimated at 65.70%, for HGSIL and squamous cell carcinoma of cervix amounted to 90.38%. Specificity of the optoelectronic method used to confirm lack of cervical pathology was estimated at 78.89%. The field under the ROC curve for the optoelectronic method was estimated at 0.88 (95% CI, 0.84-0.92) which shows high diagnostic value of the test in the detection of HGSIL and squamous cell carcinoma. The optoelectronic method is characterised by high usefulness in the detection of CIN, present in the squamous epithelium and squamous cell carcinoma of cervix.

Performance Sensitivity Studies on the PIAA Implementation of the High-Contrast Imaging Testbed

NASA Technical Reports Server (NTRS)

Sidick, Erkin; Lou, John; Shaklan, Stuart; Levine, Marie

2010-01-01

This slide presentation reviews the sensitivity studies on the Phase-Induced Amplitude Apodization (PIAA), or pupil mapping using the High-Contrast Imaging Testbed (HCIT). PIAA is a promising technique in high-dynamic range stellar coronagraph. This presentation reports on the investigation of the effects of the phase and rigid-body errors of various optics on the narrowband contrast performance of the PIAA/HCIT hybrid system. The results have shown that the 2-step wavefront control method utilizing 2-DMs is quite effective in compensating the effects of realistic phase and rigid-body errors of various optics

Highly sensitive detection of DNA methylation levels by using a quantum dot-based FRET method

NASA Astrophysics Data System (ADS)

Ma, Yunfei; Zhang, Honglian; Liu, Fangming; Wu, Zhenhua; Lu, Shaohua; Jin, Qinghui; Zhao, Jianlong; Zhong, Xinhua; Mao, Hongju

2015-10-01

DNA methylation is the most frequently studied epigenetic modification that is strongly involved in genomic stability and cellular plasticity. Aberrant changes in DNA methylation status are ubiquitous in human cancer and the detection of these changes can be informative for cancer diagnosis. Herein, we reported a facile quantum dot-based (QD-based) fluorescence resonance energy transfer (FRET) technique for the detection of DNA methylation. The method relies on methylation-sensitive restriction enzymes for the differential digestion of genomic DNA based on its methylation status. Digested DNA is then subjected to PCR amplification for the incorporation of Alexa Fluor-647 (A647) fluorophores. DNA methylation levels can be detected qualitatively through gel analysis and quantitatively by the signal amplification from QDs to A647 during FRET. Furthermore, the methylation levels of three tumor suppressor genes, PCDHGB6, HOXA9 and RASSF1A, in 20 lung adenocarcinoma and 20 corresponding adjacent nontumorous tissue (NT) samples were measured to verify the feasibility of the QD-based FRET method and a high sensitivity for cancer detection (up to 90%) was achieved. Our QD-based FRET method is a convenient, continuous and high-throughput method, and is expected to be an alternative for detecting DNA methylation as a biomarker for certain human cancers.DNA methylation is the most frequently studied epigenetic modification that is strongly involved in genomic stability and cellular plasticity. Aberrant changes in DNA methylation status are ubiquitous in human cancer and the detection of these changes can be informative for cancer diagnosis. Herein, we reported a facile quantum dot-based (QD-based) fluorescence resonance energy transfer (FRET) technique for the detection of DNA methylation. The method relies on methylation-sensitive restriction enzymes for the differential digestion of genomic DNA based on its methylation status. Digested DNA is then subjected to PCR amplification for the incorporation of Alexa Fluor-647 (A647) fluorophores. DNA methylation levels can be detected qualitatively through gel analysis and quantitatively by the signal amplification from QDs to A647 during FRET. Furthermore, the methylation levels of three tumor suppressor genes, PCDHGB6, HOXA9 and RASSF1A, in 20 lung adenocarcinoma and 20 corresponding adjacent nontumorous tissue (NT) samples were measured to verify the feasibility of the QD-based FRET method and a high sensitivity for cancer detection (up to 90%) was achieved. Our QD-based FRET method is a convenient, continuous and high-throughput method, and is expected to be an alternative for detecting DNA methylation as a biomarker for certain human cancers. Electronic supplementary information (ESI) available: Synthesis of CdSe/CdS/ZnS core/shell/shell QDs. Sequences of primers used for amplifying the promoter regions in bisulfate-modified DNA. Comparison of detected methylation levels in different gene promoters using the QD-based FRET method versus bisulfite pyrosequencing. Methylation levels of the RASSF1A gene in one pair of NT and cancer samples as indicated by pyrosequencing. Theoretical calculation of the Förster distance R0. See DOI: 10.1039/c5nr04956c

Nucleic Acid-Based Approaches for Detection of Viral Hepatitis

PubMed Central

Behzadi, Payam; Ranjbar, Reza; Alavian, Seyed Moayed

2014-01-01

Context: To determining suitable nucleic acid diagnostics for individual viral hepatitis agent, an extensive search using related keywords was done in major medical library and data were collected, categorized, and summarized in different sections. Results: Various types of molecular biology tools can be used to detect and quantify viral genomic elements and analyze the sequences. These molecular assays are proper technologies for rapidly detecting viral agents with high accuracy, high sensitivity, and high specificity. Nonetheless, the application of each diagnostic method is completely dependent on viral agent. Conclusions: Despite rapidity, automation, accuracy, cost-effectiveness, high sensitivity, and high specificity of molecular techniques, each type of molecular technology has its own advantages and disadvantages. PMID:25789132

Integrated multi-ISE arrays with improved sensitivity, accuracy and precision

NASA Astrophysics Data System (ADS)

Wang, Chunling; Yuan, Hongyan; Duan, Zhijuan; Xiao, Dan

2017-03-01

Increasing use of ion-selective electrodes (ISEs) in the biological and environmental fields has generated demand for high-sensitivity ISEs. However, improving the sensitivities of ISEs remains a challenge because of the limit of the Nernstian slope (59.2/n mV). Here, we present a universal ion detection method using an electronic integrated multi-electrode system (EIMES) that bypasses the Nernstian slope limit of 59.2/n mV, thereby enabling substantial enhancement of the sensitivity of ISEs. The results reveal that the response slope is greatly increased from 57.2 to 1711.3 mV, 57.3 to 564.7 mV and 57.7 to 576.2 mV by electronic integrated 30 Cl- electrodes, 10 F- electrodes and 10 glass pH electrodes, respectively. Thus, a tiny change in the ion concentration can be monitored, and correspondingly, the accuracy and precision are substantially improved. The EIMES is suited for all types of potentiometric sensors and may pave the way for monitoring of various ions with high accuracy and precision because of its high sensitivity.

Incorporation of beams into bossed diaphragm for a high sensitivity and overload micro pressure sensor

NASA Astrophysics Data System (ADS)

Yu, Zhongliang; Zhao, Yulong; Sun, Lu; Tian, Bian; Jiang, Zhuangde

2013-01-01

The paper presents a piezoresistive absolute micro pressure sensor, which is of great benefits for altitude location. In this investigation, the design, fabrication, and test of the sensor are involved. By analyzing the stress distribution of sensitive elements using finite element method, a novel structure through the introduction of sensitive beams into traditional bossed diaphragm is built up. The proposed configuration presents its advantages in terms of high sensitivity and high overload resistance compared with the conventional bossed diaphragm and flat diaphragm structures. Curve fittings of surface stress and deflection based on ANSYS simulation results are performed to establish the equations about the sensor. Nonlinear optimization by MATLAB is carried out to determine the structure dimensions. The output signals in both static and dynamic environments are evaluated. Silicon bulk micromachining technology is utilized to fabricate the sensor prototype, and the fabrication process is discussed. Experimental results demonstrate the sensor features a high sensitivity of 11.098 μV/V/Pa in the operating range of 500 Pa at room temperature, and a high overload resistance of 200 times overpressure to promise its survival under atmosphere. Due to the excellent performance above, the sensor can be applied in measuring the absolute micro pressure lower than 500 Pa.

A review of promising new immunoassay technology for monitoring forest herbicides

Treesearch

Charles K. McMahon

1993-01-01

Rising costs of classical instrumental methods of chemical analysis coupled with an increasing need for environmental monitoring has lead to the development of highly sensitive, low-cost immunochemical methods of analysis for the detection of environmental contaminants. These methods known simply as immunoassays are chemical assays which use antibodies as reagents. A...

Simultaneous determination of cadmium, lead and mercury ions at trace level by magnetic solid phase extraction with Fe@Ag@Dimercaptobenzene coupled to high performance liquid chromatography.

PubMed

Zhou, Qingxiang; Lei, Man; Liu, Yongli; Wu, Yalin; Yuan, Yongyong

2017-12-01

Pollution resulted from heavy metal ions have absorbed much attention, and it is of great importance to develop sensitive and simultaneous determination method for them with common technologies without highly sensitive instruments. We prepared a new and functional core-shell magnetic nano-material, Fe@Ag@dimercaptobenzene (Fe@Ag@DMB), by a one-step method with sodium borohydride as the reducing agent and transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS) were used for characterisation. The mercapto functional groups on the newly synthesised magnetic nanoparticles could interact with Cd 2+ , Pb 2+ , and Hg 2+ ions in water samples and then efficient extraction for Cd 2+ , Pb 2+ , and Hg 2+ ions was achieved. DDTC-Na solution was a good elutent for elution of these ions from Fe@Ag@DMB nanoparticles. Based on these, a sensitive method was developed for simultaneous preconcentration and determination of the aforementioned ions using magnetic Fe@Ag@DMB nanoparticles as the magnetic solid phase extraction adsorbent prior to high performance liquid chromatography coupled with variable wavelength detection. Under the optimal conditions, the detection limits of the three metal ions were in the range of 0.011-0.031μgL -1 , and precisions were below 2.37% (n=6). The proposed method was evaluated with real water samples, and excellent spiked recoveries achieved indicated that the developed method would be a promising tool for monitoring these heavy metal ions in water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Reverse phase high performance liquid chromatographic method development based on ultravioletvisible detector for the analysis of 1-hydroxypyrene (PAH biomarker) in human urine.

PubMed

Kamal, Atif; Gulfraz, Mohammad; Anwar, Mohammad Asad; Malik, Riffat Naseem

2015-01-01

1-hydroxypyrene is an important biomarker of exposure to polycyclic aromatic hydrocarbons (PAHs), which appears in the urine of exposed human subjects. In developing countries, where advanced instruments are not available, the importance of this biomarker demands convenient and sensitive methods for determination purposes. This study aimed at developing a methodology to quantify 1-hydroxypyrene (a biomarker of PAHs exposure) based on the UV-visible detector in the reverse phase high pressure liquid chromatography (HPLC). A 20 μl injection of sample was used for manual injection into the HPLC Shimadzu, equipped with the SPD-20 A UV-visible detector, the LC-20AT pump and the DGU-20A5 degasser. The C-18 column was used for the purpose of the analysis. The method showed a good linearity (the range: R² = 0.979-0.989), and high detectability up to the nmol level. The average retention was 6.37, with the accuracy of 2%, and the percentage of recovery remained 108%. The overall performance of this method was comparable (in terms of detection sensitivity) and relatively better than previously reported studies using the HPLC system equipped with the UV-detector. This method is suitable and reliable for the detection/quantification of the 1-OHP in human urine samples, using the UV-detector, however, it is less sensitive as compared to the results of a florescence detector. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Region of interest methylation analysis: a comparison of MSP with MS-HRM and direct BSP.

PubMed

Akika, Reem; Awada, Zainab; Mogharbil, Nahed; Zgheib, Nathalie K

2017-07-01

The aim of this study was to compare and contrast three DNA methylation methods of a specific region of interest (ROI): methylation-specific PCR (MSP), methylation-sensitive high resolution melting (MS-HRM) and direct bisulfite sequencing (BSP). The methylation of a CpG area in the promoter region of Estrogen receptor alpha (ESR1) was evaluated by these three methods with samples and standards of different methylation percentages. MSP data were neither reproducible nor sensitive, and the assay was not specific due to non-specific binding of primers. MS-HRM was highly reproducible and a step forward into categorizing the methylation status of the samples as percent ranges. Direct BSP was the most informative method regarding methylation percentage of each CpG site. Though not perfect, it was reproducible and sensitive. We recommend the use of either method depending on the research question and target amplicon, and provided that the designed primers and expected amplicons are within recommendations. If the research question targets a limited number of CpG sites and simple yes/no results are enough, MSP may be attempted. For short amplicons that are crowded with CpG sites and of single melting domain, MS-HRM may be the method of choice though it only indicates the overall methylation percentage of the entire amplicon. Although the assay is highly reproducible, being semi-quantitative makes it of lesser interest to study ROI methylation of samples with little methylation differences. Direct BSP is a step forward as it gives information about the methylation percentage at each CpG site.

Investigating the spring bloom initiation and net community production in the Subantarctic Southern Ocean using high-resolution in situ glider data

NASA Astrophysics Data System (ADS)

thomalla, sandy; Racault, Marie-Fanny; Swart, Sebastiaan; Monteiro, Pedro

2014-05-01

Phytoplankton bloom phenology has important consequences for marine ecosystems, fisheries and carbon export to the ocean interior. As such, it is important to examine the drivers of phytoplankton bloom initiation and their sensitivity to inter-annual climate variability and change. In this study we use ~6 months of in-situ high-resolution glider data to investigate the spring bloom initiation in the subantarctic zone (SAZ) of the Southern Ocean by implementing three different methods; a rate of change method, a threshold method and a cumulative sum method. The bloom initiation dates are critically compared to one another and the drivers of discrepancies assessed to inform on the sensitivities of different methods to processes driving the seasonal evolution of phytoplankton biomass in the subantarctic. The bloom initiation dates combined with in situ glider data of chlorophyll, light, and mixed layer depth allow us to resolve both Sverdrup's Critical Depth and Behrenfeld's Disturbance Recovery models through the water column and thus determine the seasonal evolution of net community production and respiration rates and the potential for carbon export. The outputs of the two different models are compared to one another in the context of their sensitivities to water column processes thereby refining their ability to address specific system scale questions. The novelty of this study is that gliders provide an unprecedented dataset to assess the seasonal cycle of phytoplankton biomass throughout the water column at high resolution, thus enhancing our understanding of net community production and export processes at submeso-space and sub-seasonal time scales.

Design of highly sensitive multichannel bimetallic photonic crystal fiber biosensor

NASA Astrophysics Data System (ADS)

Hameed, Mohamed Farhat O.; Alrayk, Yassmin K. A.; Shaalan, Abdelhamid A.; El Deeb, Walid S.; Obayya, Salah S. A.

2016-10-01

A design of a highly sensitive multichannel biosensor based on photonic crystal fiber is proposed and analyzed. The suggested design has a silver layer as a plasmonic material coated by a gold layer to protect silver oxidation. The reported sensor is based on detection using the quasi transverse electric (TE) and quasi transverse magnetic (TM) modes, which offers the possibility of multichannel/multianalyte sensing. The numerical results are obtained using a finite element method with perfect matched layer boundary conditions. The sensor geometrical parameters are optimized to achieve high sensitivity for the two polarized modes. High-refractive index sensitivity of about 4750 nm/RIU (refractive index unit) and 4300 nm/RIU with corresponding resolutions of 2.1×10-5 RIU, and 2.33×10-5 RIU can be obtained according to the quasi TM and quasi TE modes of the proposed sensor, respectively. Further, the reported design can be used as a self-calibration biosensor within an unknown analyte refractive index ranging from 1.33 to 1.35 with high linearity and high accuracy. Moreover, the suggested biosensor has advantages in terms of compactness and better integration of microfluidics setup, waveguide, and metallic layers into a single structure.

The advance of non-invasive detection methods in osteoarthritis

NASA Astrophysics Data System (ADS)

Dai, Jiao; Chen, Yanping

2011-06-01

Osteoarthritis (OA) is one of the most prevalent chronic diseases which badly affected the patients' living quality and economy. Detection and evaluation technology can provide basic information for early treatment. A variety of imaging methods in OA were reviewed, such as conventional X-ray, computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI) and near-infrared spectroscopy (NIRS). Among the existing imaging modalities, the spatial resolution of X-ray is extremely high; CT is a three-dimensional method, which has high density resolution; US as an evaluation method of knee OA discriminates lesions sensitively between normal cartilage and degenerative one; as a sensitive and nonionizing method, MRI is suitable for the detection of early OA, but the cost is too expensive for routine use; NIRS is a safe, low cost modality, and is also good at detecting early stage OA. In a word, each method has its own advantages, but NIRS is provided with broader application prospect, and it is likely to be used in clinical daily routine and become the golden standard for diagnostic detection.

All-fiber magnetic field sensor based on tapered thin-core fiber and magnetic fluid.

PubMed

Zhang, Junying; Qiao, Xueguang; Yang, Hangzhou; Wang, Ruohui; Rong, Qiangzhou; Lim, Kok-Sing; Ahmad, Harith

2017-01-10

A method for the measurement of a magnetic field by combining a tapered thin-core fiber (TTCF) and magnetic fluid is proposed and experimentally demonstrated. The modal interference effect is caused by the core mode and excited eigenmodes in the TTCF cladding. The transmission spectra of the proposed sensor are measured and theoretically analyzed at different magnetic field strengths. The results field show that the magnetic sensitivity reaches up to -0.1039  dB/Oe in the range of 40-1600 e. The proposed method possesses high sensitivity and low cost compared with other expensive methods.

Citation searches are more sensitive than keyword searches to identify studies using specific measurement instruments.

PubMed

Linder, Suzanne K; Kamath, Geetanjali R; Pratt, Gregory F; Saraykar, Smita S; Volk, Robert J

2015-04-01

To compare the effectiveness of two search methods in identifying studies that used the Control Preferences Scale (CPS), a health care decision-making instrument commonly used in clinical settings. We searched the literature using two methods: (1) keyword searching using variations of "Control Preferences Scale" and (2) cited reference searching using two seminal CPS publications. We searched three bibliographic databases [PubMed, Scopus, and Web of Science (WOS)] and one full-text database (Google Scholar). We report precision and sensitivity as measures of effectiveness. Keyword searches in bibliographic databases yielded high average precision (90%) but low average sensitivity (16%). PubMed was the most precise, followed closely by Scopus and WOS. The Google Scholar keyword search had low precision (54%) but provided the highest sensitivity (70%). Cited reference searches in all databases yielded moderate sensitivity (45-54%), but precision ranged from 35% to 75% with Scopus being the most precise. Cited reference searches were more sensitive than keyword searches, making it a more comprehensive strategy to identify all studies that use a particular instrument. Keyword searches provide a quick way of finding some but not all relevant articles. Goals, time, and resources should dictate the combination of which methods and databases are used. Copyright © 2015 Elsevier Inc. All rights reserved.

Citation searches are more sensitive than keyword searches to identify studies using specific measurement instruments

PubMed Central

Linder, Suzanne K.; Kamath, Geetanjali R.; Pratt, Gregory F.; Saraykar, Smita S.; Volk, Robert J.

2015-01-01

Objective To compare the effectiveness of two search methods in identifying studies that used the Control Preferences Scale (CPS), a healthcare decision-making instrument commonly used in clinical settings. Study Design & Setting We searched the literature using two methods: 1) keyword searching using variations of “control preferences scale” and 2) cited reference searching using two seminal CPS publications. We searched three bibliographic databases [PubMed, Scopus, Web of Science (WOS)] and one full-text database (Google Scholar). We report precision and sensitivity as measures of effectiveness. Results Keyword searches in bibliographic databases yielded high average precision (90%), but low average sensitivity (16%). PubMed was the most precise, followed closely by Scopus and WOS. The Google Scholar keyword search had low precision (54%) but provided the highest sensitivity (70%). Cited reference searches in all databases yielded moderate sensitivity (45–54%), but precision ranged from 35–75% with Scopus being the most precise. Conclusion Cited reference searches were more sensitive than keyword searches, making it a more comprehensive strategy to identify all studies that use a particular instrument. Keyword searches provide a quick way of finding some but not all relevant articles. Goals, time and resources should dictate the combination of which methods and databases are used. PMID:25554521

Rapid and sensitive detection of mink circovirus by recombinase polymerase amplification.

PubMed

Ge, Junwei; Shi, Yunjia; Cui, Xingyang; Gu, Shanshan; Zhao, Lili; Chen, Hongyan

2018-06-01

To date, the pathogenic role of mink circovirus (MiCV) remains unclear, and its prevalence and economic importance are unknown. Therefore, a rapid and sensitive molecular diagnosis is necessary for disease management and epidemiological surveillance. However, only PCR methods can identify MiCV infection at present. In this study, we developed a nested PCR and established a novel recombinase polymerase amplification (RPA) assay for MiCV detection. Sensitivity analysis showed that the detection limit of nested PCR and RPA assay was 10 1 copies/reaction, and these methods were more sensitive than conventional PCR, which has a detection limit of 10 5 copies/reaction. The RPA assay had no cross-reactivity with other related viral pathogens, and amplification was completed in less than 20 min with a simple device. Further assessment of clinical samples showed that the two assays were accurate in identifying positive and negative conventional PCR samples. The detection rate of MiCV by the RPA assay in clinical samples was 38.09%, which was 97% consistent with that by the nested PCR. The developed nested PCR is a highly sensitive tool for practical use, and the RPA assay is a simple, sensitive, and potential alternative method for rapid and accurate MiCV diagnosis. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhancement of NH3 gas sensitivity at room temperature by carbon nanotube-based sensor coated with Co nanoparticles.

PubMed

Nguyen, Lich Quang; Phan, Pho Quoc; Duong, Huyen Ngoc; Nguyen, Chien Duc; Nguyen, Lam Huu

2013-01-30

Multi-walled carbon nanotube (MWCNT) film has been fabricated onto Pt-patterned alumina substrates using the chemical vapor deposition method for NH(3) gas sensing applications. The MWCNT-based sensor is sensitive to NH(3) gas at room temperature. Nanoclusters of Co catalysts have been sputtered on the surface of the MWCNT film to enhance gas sensitivity with respect to unfunctionalized CNT films. The gas sensitivity of Co-functionalized MWCNT-based gas sensors is thus significantly improved. The sensor exhibits good repeatability and high selectivity towards NH(3), compared with alcohol and LPG.

Ultrafast Fabrication of Flexible Dye-Sensitized Solar Cells by Ultrasonic Spray-Coating Technology

PubMed Central

Han, Hyun-Gyu; Weerasinghe, Hashitha C.; Min Kim, Kwang; Soo Kim, Jeong; Cheng, Yi-Bing; Jones, David J.; Holmes, Andrew B.; Kwon, Tae-Hyuk

2015-01-01

This study investigates novel deposition techniques for the preparation of TiO2 electrodes for use in flexible dye-sensitized solar cells. These proposed new methods, namely pre-dye-coating and codeposition ultrasonic spraying, eliminate the conventional need for time-consuming processes such as dye soaking and high-temperature sintering. Power conversion efficiencies of over 4.0% were achieved with electrodes prepared on flexible polymer substrates using this new deposition technology and N719 dye as a sensitizer. PMID:26420466

Chemically Amplified Bilevel Resist Based on Condensation of Siloxanes

NASA Astrophysics Data System (ADS)

Sakata, Miwa; Ito, Toshio; Yamashita, Yoshio

1991-11-01

This paper deals with a negative bilevel resist which is based on the acid-catalyzed condensation reaction of poly(siloxane)s. The resist systems consist of photoacid generators and poly(siloxane). Ph3S+OTf- reveals an efficient activity for silanol condensation and the system has a high sensitivity of 0.31 mJ/cm2. Tetrafunctional silane plays the role of crosslinker in this system. Sensitivity improvement of low-sensitivity systems such as benzoin p-toluenesulfonate/poly(siloxane) can be achieved by this method.

Ultra high vacuum pumping system and high sensitivity helium leak detector

DOEpatents

Myneni, G.R.

1997-12-30

An improved helium leak detection method and apparatus are disclosed which increase the leak detection sensitivity to 10{sup {minus}13} atm cc/s. The leak detection sensitivity is improved over conventional leak detectors by completely eliminating the use of o-rings, equipping the system with oil-free pumping systems, and by introducing measured flows of nitrogen at the entrances of both the turbo pump and backing pump to keep the system free of helium background. The addition of dry nitrogen flows to the system reduces back streaming of atmospheric helium through the pumping system as a result of the limited compression ratios of the pumps for helium. 2 figs.

Wide-Field Imaging of Single-Nanoparticle Extinction with Sub-nm2 Sensitivity

NASA Astrophysics Data System (ADS)

Payne, Lukas M.; Langbein, Wolfgang; Borri, Paola

2018-03-01

We report on a highly sensitive wide-field imaging technique for quantitative measurement of the optical extinction cross section σext of single nanoparticles. The technique is simple and high speed, and it enables the simultaneous acquisition of hundreds of nanoparticles for statistical analysis. Using rapid referencing, fast acquisition, and a deconvolution analysis, a shot-noise-limited sensitivity down to 0.4 nm2 is achieved. Measurements on a set of individual gold nanoparticles of 5 nm diameter using this method yield σext=(10.0 ±3.1 ) nm2, which is consistent with theoretical expectations and well above the background fluctuations of 0.9 nm2 .

Direct determination of trace phthalate esters in alcoholic spirits by spray-inlet microwave plasma torch ionization tandem mass spectrometry.

PubMed

Miao, Meng; Zhao, Gaosheng; Xu, Li; Dong, Junguo; Cheng, Ping

2018-03-01

A direct analytical method based on spray-inlet microwave plasma torch tandem mass spectrometry was applied to simultaneously determine 4 phthalate esters (PAEs), namely, benzyl butyl phthalate, diethyl phthalate, dipentyl phthalate, and dodecyl phthalate with extremely high sensitivity in spirits without sample treatment. Among the 4 brands of spirit products, 3 kinds of PAE compounds were directly determined at very low concentrations from 1.30 to 114 ng·g -1 . Compared with other online and off-line methods, the spray-inlet microwave plasma torch tandem mass spectrometry technique is extremely simple, rapid, sensitive, and high efficient, providing an ideal screening tool for PAEs in spirits. Copyright © 2017 John Wiley & Sons, Ltd.

Predicting metabolic syndrome using decision tree and support vector machine methods.

PubMed

Karimi-Alavijeh, Farzaneh; Jalili, Saeed; Sadeghi, Masoumeh

2016-05-01

Metabolic syndrome which underlies the increased prevalence of cardiovascular disease and Type 2 diabetes is considered as a group of metabolic abnormalities including central obesity, hypertriglyceridemia, glucose intolerance, hypertension, and dyslipidemia. Recently, artificial intelligence based health-care systems are highly regarded because of its success in diagnosis, prediction, and choice of treatment. This study employs machine learning technics for predict the metabolic syndrome. This study aims to employ decision tree and support vector machine (SVM) to predict the 7-year incidence of metabolic syndrome. This research is a practical one in which data from 2107 participants of Isfahan Cohort Study has been utilized. The subjects without metabolic syndrome according to the ATPIII criteria were selected. The features that have been used in this data set include: gender, age, weight, body mass index, waist circumference, waist-to-hip ratio, hip circumference, physical activity, smoking, hypertension, antihypertensive medication use, systolic blood pressure (BP), diastolic BP, fasting blood sugar, 2-hour blood glucose, triglycerides (TGs), total cholesterol, low-density lipoprotein, high density lipoprotein-cholesterol, mean corpuscular volume, and mean corpuscular hemoglobin. Metabolic syndrome was diagnosed based on ATPIII criteria and two methods of decision tree and SVM were selected to predict the metabolic syndrome. The criteria of sensitivity, specificity and accuracy were used for validation. SVM and decision tree methods were examined according to the criteria of sensitivity, specificity and accuracy. Sensitivity, specificity and accuracy were 0.774 (0.758), 0.74 (0.72) and 0.757 (0.739) in SVM (decision tree) method. The results show that SVM method sensitivity, specificity and accuracy is more efficient than decision tree. The results of decision tree method show that the TG is the most important feature in predicting metabolic syndrome. According to this study, in cases where only the final result of the decision is regarded significant, SVM method can be used with acceptable accuracy in decision making medical issues. This method has not been implemented in the previous research.

Operational Implementation of LED Fluorescence Microscopy in Screening Tuberculosis Suspects in an Urban HIV Clinic in Uganda

PubMed Central

Albert, Heidi; Nakiyingi, Lydia; Sempa, Joseph; Mbabazi, Olive; Mukkada, Sheena; Nyesiga, Barnabas; Perkins, Mark D.; Manabe, Yukari C.

2013-01-01

Background Light emitting diode (LED) fluorescence microscopy (FM) is an affordable, technology targeted for use in resource-limited settings and recommended for widespread roll-out by the World Health Organization (WHO). We sought to compare the operational performance of three LED FM methods compared to light microscopy in a cohort of HIV-positive tuberculosis (TB) suspects at an urban clinic in a high TB burden country. Methods Two spot specimens collected from TB suspects were included in the study. Smears were stained using auramine O method and read after blinding by three LED-based FM methods by trained laboratory technicians in the Infectious Diseases Institutelaboratory. Leftover portions of the refrigerated sputum specimens were transported to the FIND Tuberculosis Research Laboratory for Ziehl Neelsen (ZN) smear preparation and reading by experienced technologist as well as liquid and solid culture. Results 174 of 627 (27.8%) specimens collected yielded one or more positive mycobacterial cultures. 94.3% (164/174) were M. tuberculosis complex. LED FM was between 7.3–11.0% more sensitive compared to ZN microscopy. Of the 592 specimens examined by all microscopy methods, there was no significant difference in sensitivity between the three LED FM methods. The specificity of the LED FM methods was between 6.1% and 7.7% lower than ZN microscopy (P<0.001), although exclusion of the single poor reader resulted in over 98% specificity for all FM methods. Conclusions Laboratory technicians in routine settings can be trained to use FM which is more sensitive than ZN microscopy. Despite rigorous proficiency testing, there were operator-dependent accuracy issues which highlight the critical need for intensive quality assurance procedures during LED FM implementation. The low sensitivity of FM for HIV-positive individuals particularly those with low CD4 T cell counts, will limit the number of additional patients found by LED FM in countries with high rates of HIV co-infection. PMID:24039780

Sensitivity of ab Initio vs Empirical Methods in Computing Structural Effects on NMR Chemical Shifts for the Example of Peptides.

PubMed

Sumowski, Chris Vanessa; Hanni, Matti; Schweizer, Sabine; Ochsenfeld, Christian

2014-01-14

The structural sensitivity of NMR chemical shifts as computed by quantum chemical methods is compared to a variety of empirical approaches for the example of a prototypical peptide, the 38-residue kaliotoxin KTX comprising 573 atoms. Despite the simplicity of empirical chemical shift prediction programs, the agreement with experimental results is rather good, underlining their usefulness. However, we show in our present work that they are highly insensitive to structural changes, which renders their use for validating predicted structures questionable. In contrast, quantum chemical methods show the expected high sensitivity to structural and electronic changes. This appears to be independent of the quantum chemical approach or the inclusion of solvent effects. For the latter, explicit solvent simulations with increasing number of snapshots were performed for two conformers of an eight amino acid sequence. In conclusion, the empirical approaches neither provide the expected magnitude nor the patterns of NMR chemical shifts determined by the clearly more costly ab initio methods upon structural changes. This restricts the use of empirical prediction programs in studies where peptide and protein structures are utilized for the NMR chemical shift evaluation such as in NMR refinement processes, structural model verifications, or calculations of NMR nuclear spin relaxation rates.

Study on room temperature gas-sensing performance of CuO film-decorated ordered porous ZnO composite by In2O3 sensitization

NASA Astrophysics Data System (ADS)

Li, Tian-tian; Bao, Na; Geng, Ai-fang; Yu, Hui; Yang, Ying; Dong, Xiang-ting

2018-02-01

For the first time, ordered mesoporous ZnO nanoparticles have been synthesized by a template method. The electroplating after chemical plating method was creatively used to form copper film on the surface of the prepared ZnO, and then a CuO film-decorated ordered porous ZnO composite (CuO/ZnO) was obtained by a high-temperature oxidation method. In2O3 was loaded into the prepared CuO film-ZnO by an ultrasonic-assisted method to sensitize the room temperature gas-sensing performance of the prepared CuO/ZnO materials. The doped In2O3 could effectively improve the gas-sensing properties of the prepared materials to nitrogen oxides (NOx) at room temperature. The 1% In2O3 doped CuO/ZnO sample (1 wt% In2O3-CuO/ZnO) showed the best gas-sensing properties whose response to 100 ppm NOx reached 82%, and the detectable minimum concentration reached 1 ppm at room temperature. The prepared materials had a good selectivity, better response, very low detection limit, and high sensitivity to NOx gas at room temperature, which would have a great development space in the gas sensor field and a great research value.

Highly sensitive surface enhanced Raman scattering substrates based on Ag decorated Si nanocone arrays and their application in trace dimethyl phthalate detection

NASA Astrophysics Data System (ADS)

Zuo, Zewen; Zhu, Kai; Ning, Lixin; Cui, Guanglei; Qu, Jun; Cheng, Ying; Wang, Junzhuan; Shi, Yi; Xu, Dongsheng; Xin, Yu

2015-01-01

Wafer-scale three-dimensional (3D) surface enhancement Raman scattering (SERS) substrates were prepared using the plasma etching and ion sputtering methods that are completely compatible with well-established silicon device technologies. The substrates are highly sensitive with excellent uniformity and reproducibility, exhibiting an enhancement factor up to 1012 with a very low relative standard deviation (RSD) around 5%. These are attributed mainly to the uniform-distributed, multiple-type high-density hot spots originating from the structural characteristics of Ag nanoparticles (NPs) decorated Si nanocone (NC) arrays. We demonstrate that the trace dimethyl phthalate (DMP) at a concentration of 10-7 M can be well detected using this SERS substrate, showing that the AgNPs-decorated SiNC arrays can serve as efficient SERS substrates for phthalate acid esters (PAEs) detection with high sensitivity.

Three-dimensional conformal graphene microstructure for flexible and highly sensitive electronic skin

NASA Astrophysics Data System (ADS)

Yang, Jun; Ran, Qincui; Wei, Dapeng; Sun, Tai; Yu, Leyong; Song, Xuefen; Pu, Lichun; Shi, Haofei; Du, Chunlei

2017-03-01

We demonstrate a highly stretchable electronic skin (E-skin) based on the facile combination of microstructured graphene nanowalls (GNWs) and a polydimethylsiloxane (PDMS) substrate. The microstructure of the GNWs was endowed by conformally growing them on the unpolished silicon wafer without the aid of nanofabrication technology. Then a stamping transfer method was used to replicate the micropattern of the unpolished silicon wafer. Due to the large contact interface between the 3D graphene network and the PDMS, this type of E-skin worked under a stretching ratio of nearly 100%, and showed excellent mechanical strength and high sensitivity, with a change in relative resistance of up to 6500% and a gauge factor of 65.9 at 99.64% strain. Furthermore, the E-skin exhibited an obvious highly sensitive response to joint movement, eye movement and sound vibration, demonstrating broad potential applications in healthcare, body monitoring and wearable devices.

Detecting atrial fibrillation by deep convolutional neural networks.

PubMed

Xia, Yong; Wulan, Naren; Wang, Kuanquan; Zhang, Henggui

2018-02-01

Atrial fibrillation (AF) is the most common cardiac arrhythmia. The incidence of AF increases with age, causing high risks of stroke and increased morbidity and mortality. Efficient and accurate diagnosis of AF based on the ECG is valuable in clinical settings and remains challenging. In this paper, we proposed a novel method with high reliability and accuracy for AF detection via deep learning. The short-term Fourier transform (STFT) and stationary wavelet transform (SWT) were used to analyze ECG segments to obtain two-dimensional (2-D) matrix input suitable for deep convolutional neural networks. Then, two different deep convolutional neural network models corresponding to STFT output and SWT output were developed. Our new method did not require detection of P or R peaks, nor feature designs for classification, in contrast to existing algorithms. Finally, the performances of the two models were evaluated and compared with those of existing algorithms. Our proposed method demonstrated favorable performances on ECG segments as short as 5 s. The deep convolutional neural network using input generated by STFT, presented a sensitivity of 98.34%, specificity of 98.24% and accuracy of 98.29%. For the deep convolutional neural network using input generated by SWT, a sensitivity of 98.79%, specificity of 97.87% and accuracy of 98.63% was achieved. The proposed method using deep convolutional neural networks shows high sensitivity, specificity and accuracy, and, therefore, is a valuable tool for AF detection. Copyright © 2017 Elsevier Ltd. All rights reserved.

MMASS: an optimized array-based method for assessing CpG island methylation.

PubMed

Ibrahim, Ashraf E K; Thorne, Natalie P; Baird, Katie; Barbosa-Morais, Nuno L; Tavaré, Simon; Collins, V Peter; Wyllie, Andrew H; Arends, Mark J; Brenton, James D

2006-01-01

We describe an optimized microarray method for identifying genome-wide CpG island methylation called microarray-based methylation assessment of single samples (MMASS) which directly compares methylated to unmethylated sequences within a single sample. To improve previous methods we used bioinformatic analysis to predict an optimized combination of methylation-sensitive enzymes that had the highest utility for CpG-island probes and different methods to produce unmethylated representations of test DNA for more sensitive detection of differential methylation by hybridization. Subtraction or methylation-dependent digestion with McrBC was used with optimized (MMASS-v2) or previously described (MMASS-v1, MMASS-sub) methylation-sensitive enzyme combinations and compared with a published McrBC method. Comparison was performed using DNA from the cell line HCT116. We show that the distribution of methylation microarray data is inherently skewed and requires exogenous spiked controls for normalization and that analysis of digestion of methylated and unmethylated control sequences together with linear fit models of replicate data showed superior statistical power for the MMASS-v2 method. Comparison with previous methylation data for HCT116 and validation of CpG islands from PXMP4, SFRP2, DCC, RARB and TSEN2 confirmed the accuracy of MMASS-v2 results. The MMASS-v2 method offers improved sensitivity and statistical power for high-throughput microarray identification of differential methylation.

Materials, methods and devices to detect and quantify water vapor concentrations in an atmosphere

DOEpatents

Allendorf, Mark D; Robinson, Alex L

2014-12-09

We have demonstrated that a surface acoustic wave (SAW) sensor coated with a nanoporous framework material (NFM) film can perform ultrasensitive water vapor detection at concentrations in air from 0.05 to 12,000 ppmv at 1 atmosphere pressure. The method is extendable to other MEMS-based sensors, such as microcantilevers, or to quartz crystal microbalance sensors. We identify a specific NFM that provides high sensitivity and selectivity to water vapor. However, our approach is generalizable to detection of other species using NFM to provide sensitivity and selectivity.

Phase-sensitive atomic dynamics in quantum light

NASA Astrophysics Data System (ADS)

Balybin, S. N.; Zakharov, R. V.; Tikhonova, O. V.

2018-05-01

Interaction between a quantum electromagnetic field and a model Ry atom with possible transitions to the continuum and to the low-lying resonant state is investigated. Strong sensitivity of atomic dynamics to the phase of applied coherent and squeezed vacuum light is found. Methods to extract the quantum field phase performing the measurements on the atomic system are proposed. In the case of the few-photon coherent state high accuracy of the phase determination is demonstrated, which appears to be much higher in comparison to the usually used quantum-optical methods such as homodyne detection.

Deep Whole-Genome Sequencing to Detect Mixed Infection of Mycobacterium tuberculosis

PubMed Central

Gan, Mingyu; Liu, Qingyun; Yang, Chongguang; Gao, Qian; Luo, Tao

2016-01-01

Mixed infection by multiple Mycobacterium tuberculosis (MTB) strains is associated with poor treatment outcome of tuberculosis (TB). Traditional genotyping methods have been used to detect mixed infections of MTB, however, their sensitivity and resolution are limited. Deep whole-genome sequencing (WGS) has been proved highly sensitive and discriminative for studying population heterogeneity of MTB. Here, we developed a phylogenetic-based method to detect MTB mixed infections using WGS data. We collected published WGS data of 782 global MTB strains from public database. We called homogeneous and heterogeneous single nucleotide variations (SNVs) of individual strains by mapping short reads to the ancestral MTB reference genome. We constructed a phylogenomic database based on 68,639 homogeneous SNVs of 652 MTB strains. Mixed infections were determined if multiple evolutionary paths were identified by mapping the SNVs of individual samples to the phylogenomic database. By simulation, our method could specifically detect mixed infections when the sequencing depth of minor strains was as low as 1× coverage, and when the genomic distance of two mixed strains was as small as 16 SNVs. By applying our methods to all 782 samples, we detected 47 mixed infections and 45 of them were caused by locally endemic strains. The results indicate that our method is highly sensitive and discriminative for identifying mixed infections from deep WGS data of MTB isolates. PMID:27391214