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Sample records for highly sensitive determination

  1. Highly sensitive catalytic spectrophotometric determination of ruthenium

    Science.gov (United States)

    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.

  2. Highly sensitive flow-injection chemiluminescence determination of pyrogallol compounds

    Science.gov (United States)

    Kanwal, Shamsa; Fu, Xiaohong; Su, Xingguang

    2009-12-01

    A highly sensitive flow-injection chemiluminescent method for the direct determination of pyrogallol compounds has been developed. Proposed method is based on the enhanced effect of pyrogallol compounds on the chemiluminescence signals of KMnO 4-H 2O 2 system in slightly alkaline medium. Three important pyrogallol compounds, pyrogallic acid, gallic acid and tannic acid, have been detected by this method, and the possible mechanism of the CL reaction is also discussed. The proposed method is simple, convenient, rapid (60 samples h -1), and sensitive, has a linear range of 8 × 10 -10 mol L -1 to 1 × 10 -5 mol L -1, for pyrogallic acid, with a detection limit of 6 × 10 -11 mol L -1, 4 × 10 -8 mol L -1 to 5 × 10 -3 mol L -1 for gallic acid with a detection limit of 9 × 10 -10 mol L -1, and 8 × 10 -8 mol L -1 to 5 × 10 -2 mol L -1 for tannic acid, with a detection limit of 2 × 10 -9 mol L -1, respectively. The relative standard deviation (RSD, n = 15) was 0.8, 1.1 and 1.3% for 5 × 10 -6 mol L -1 pyrogallic acid, gallic acid and tannic acid, respectively. The proposed method was successfully applied to the determination of pyrogallol compounds in tea and coffee samples.

  3. Portable High Sensitivity and High Resolution Sensor to Determine Oxygen Purity Levels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this Phase I STTR project is to develop a highly sensitive oxygen (O2) sensor, with high accuracy and precision, to determine purity levels of high...

  4. Highly sensitive spectrofluorimetric method for determination of certain aminoglycosides in pharmaceutical formulations and human plasma.

    Science.gov (United States)

    Omar, Mahmoud A; Nagy, Dalia M; Hammad, Mohamed A; Aly, Alshymaa A

    2013-06-01

    A simple, reliable, highly sensitive and selective spectrofluorimetric method has been developed for determination of certain aminoglycosides namely amikacin sulfate, tobramycin, neomycin sulfate, gentamicin sulfate, kanamycin sulfate and streptomycin sulfate. The method is based on the formation of a charge transfer complexes between these drugs and safranin in buffer solution of pH 8. The formed complexes were quantitatively extracted with chloroform under the optimized experimental conditions. These complexes showed an excitation maxima at 519-524 nm and emission maxima at 545-570 nm. The calibration plots were constructed over the range of 4-60 pg mL(-1) for amikacin, 4-50 pg mL(-1) for gentamicin, neomycin and kanamycin, 4-40 pg mL(-1) for streptomycin and 5-50 pg mL(-1) for tobramycin. The proposed method was successfully applied to the analysis of the cited drugs in dosage forms. The proposed method was validated according to ICH and USP guidelines with respect to specificity, linearity, accuracy, precision and robustness. The high sensitivity of the proposed method allowed determination of amikacin and gentamicin in spiked and real human plasma.

  5. Highly Sensitive Colorimetric Assay for Determining Fe3+ Based on Gold Nanoparticles Conjugated with Glycol Chitosan

    Directory of Open Access Journals (Sweden)

    Kyungmin Kim

    2017-01-01

    Full Text Available A highly sensitive and simple colorimetric assay for the detection of Fe3+ ions was developed using gold nanoparticles (AuNPs conjugated with glycol chitosan (GC. The Fe3+ ion coordinates with the oxygen atoms of GC in a hexadentate manner (O-Fe3+-O, decreasing the interparticle distance and inducing aggregation. Time-of-flight secondary ion mass spectrometry showed that the bound Fe3+ was coordinated to the oxygen atoms of the ethylene glycol in GC, which resulted in a significant color change from light red to dark midnight blue due to aggregation. Using this GC-AuNP probe, the quantitative determination of Fe3+ in biological, environmental, and pharmaceutical samples could be achieved by the naked eye and spectrophotometric methods. Sensitive response and pronounced color change of the GC-AuNPs in the presence of Fe3+ were optimized at pH 6, 70°C, and 300 mM NaCl concentration. The absorption intensity ratio (A700/A510 linearly correlated to the Fe3+ concentration in the linear range of 0–180 μM. The limits of detection were 11.3, 29.2, and 46.0 nM for tap water, pond water, and iron supplement tablets, respectively. Owing to its facile and sensitive nature, this assay method for Fe3+ ions can be applied to the analysis of drinking water and pharmaceutical samples.

  6. Magnetoresistive polyaniline-silicon carbide metacomposites: plasma frequency determination and high magnetic field sensitivity.

    Science.gov (United States)

    Gu, Hongbo; Guo, Jiang; Khan, Mojammel Alam; Young, David P; Shen, T D; Wei, Suying; Guo, Zhanhu

    2016-07-20

    The Drude model modified by Debye relaxation time was introduced to determine the plasma frequency (ωp) in the surface initiated polymerization (SIP) synthesized β-silicon carbide (β-SiC)/polyaniline (PANI) metacomposites. The calculated plasma frequency for these metacomposites with different loadings of β-SiC nanoparticles was ranging from 6.11 × 10(4) to 1.53 × 10(5) rad s(-1). The relationship between the negative permittivity and plasma frequency indicates the existence of switching frequency, at which the permittivity was changed from negative to positive. More interestingly, the synthesized non-magnetic metacomposites, observed to follow the 3-dimensional (3-D) Mott variable range hopping (VRH) electrical conduction mechanism, demonstrated high positive magnetoresistance (MR) values of up to 57.48% and high MR sensitivity at low magnetic field regimes.

  7. Spectrophotometric and high performance liquid chromatographic methods for sensitive determination of bisphenol A.

    Science.gov (United States)

    Zhuang, Yafeng; Zhou, Meng; Gu, Jia; Li, Xiangmei

    2014-03-25

    A new spectrophotometric method for the determination of trace amounts of bisphenol A based on a diazotization-coupling reaction was developed. In acidic solution, clenbuterol was first diazotized with sodium nitrite, then coupled with bisphenol A to from an azo-compound [I] in NH3-NH4Cl buffer, which shows a maximum absorption at 410 nm. The effects of the amount of sodium nitrite, diazo reaction time, the amount of clenbuterol, coupling reaction time and coupling reaction temperature have been examined. Under the optional conditions, the determination of the linear range of bisphenol A is 0.24-8.4 μg/mL, correlation coefficient is 0.9905 and detection limit of this method is 0.15 μg/mL. The spectrophotometric method is simple, rapid, high sensitivity with better accuracy. High performance liquid chromatography (HPLC) technique combined with this new spectrophotometric method has been also developed for the measurement of bisphenol A. The analysis was achieved on a C18 column using water and methanol as a mobile phase and the detection was done spectrophotometrically at 410 nm. These reported methods were applied to the determination of bisphenol A in hot water in contact with commercially available table-water bottle samples.

  8. High-performance liquid chromatographic determination of vertilmicin in rat plasma using sensitive fluorometric derivatization.

    Science.gov (United States)

    Liu, Zhen; Sha, Yunfei; Huang, Taomin; Yang, Bei; Duan, Geng-Li

    2005-12-15

    A sensitive and reliable high-performance liquid chromatographic method was developed for the determination of vertilmicin in rat plasma. Derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by C(18) reversed-phase chromatography allowed the fluorimetric detection of vertilmicin. Optimal conditions for the derivatization of vertilmicin are described. The limit of quantification was 0.02 mg/L. The pharmacokinetics of vertilmicin was studied in 24 rats following intramuscular injection (i.m.) of different doses (4, 8, 16, 32 mg/kg of body weight). The pharmacokinetic parameter values were estimated by use of 3P97 program. In this study, we assessed the dose proportionality of vertilmicin after single intramuscular injection doses and obtained new information on the pharmacokinetics of the compound.

  9. Highly sensitive ion pair liquid chromatographic determination of albendazole marker residue in animal tissues.

    Science.gov (United States)

    Fletouris, Dimitrios J; Papapanagiotou, Elias P; Nakos, Dimitrios S; Psomas, Ioannis E

    2005-02-23

    A simple, rapid, and highly sensitive ion pair liquid chromatographic method for the determination of albendazole sulfoxide, albendazole 2-aminosulfone, and albendazole sulfone, which constitute the marker residue of albendazole in animal tissues (muscle, fat, liver, and kidney), is described. Tissue samples were extracted with acetonitrile, and the extracts were partitioned, as ion pairs, into dichloromethane. The organic layer was evaporated to dryness, and the residue was reconstituted in phosphate buffer and extracted with ethyl acetate. Separation was carried out isocratically with a mobile phase containing both positively and negatively charged pairing ions. Detection was performed fluorometrically, with excitation and emission wavelengths set at 290 and 320 nm, respectively. Overall recoveries were better than 76%, and the overall relative standard deviation was better than 7.3% in all tissues examined. The limits of quantification were 20, 1, and 0.5 ng/g for sulfoxide, 2-aminosulfone, and sulfone metabolites, respectively. The method was successfully applied to determine residues in tissues of two sheep orally administered an albendazole formulation.

  10. Fabrication of highly sensitive gold nanourchins based electrochemical sensor for nanomolar determination of primaquine.

    Science.gov (United States)

    Thapliyal, Neeta Bachheti; Chiwunze, Tirivashe Elton; Karpoormath, Rajshekhar; Cherukupalli, Srinivasulu

    2017-05-01

    A gold nanourchins modified glassy carbon electrode (AuNu/GCE) was developed for the determination of antimalarial drug, primaquine (PQ). The surface of AuNu/GCE was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV). EIS results indicated that the electron transfer process at AuNu/GCE was faster as compared to the bare electrode. The SEM and TEM image confirmed the presence and uniform dispersion of gold nanourchins on the GCE surface. Upon investigating the electrochemical behavior of PQ at AuNu/GCE, the developed sensor was found to exhibit high electrocatalytic activity towards the oxidation of PQ. Under optimal experimental conditions, the sensor showed fast and sensitive current response to PQ over a linear concentration range of 0.01-1μM and 0.001-1μM with a detection limit of 3.5nM and 0.9nM using differential pulse voltammetry (DPV) and square wave voltammetry (SWV), respectively. The AuNu/GCE showed good selectivity, reproducibility and stability. Further, the developed sensor was successfully applied to determine the drug in human urine samples and pharmaceutical formulations demonstrating its analytical applicability in clinical analysis as well as quality control. The proposed method thus provides a promising alternative in routine sensing of PQ as well as promotes the application of gold nanourchins in electrochemical sensors. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. A Highly Sensitive Resonance Rayleigh Scattering Method for the Determination of Penicillin Antibiotics with Potassium Ferricyanide

    Institute of Scientific and Technical Information of China (English)

    DUAN Hui; LIU Zhong-Fang; LIU Shao-Pu; KONG Ling

    2008-01-01

    Heated in a boiling water bath, penicillin antibiotics such as amoxicillin, ampicillin, sodium cloxacillin, sodium carbenicillin and sodium benzylpenicillin could react with K3[Fe(CN)6] to form combined products in a dilute HCl medium.As a result, resonance Rayleigh scattering (RRS) intensity was enhanced greatly and new RRS spectra appeared.The maximum scattering wavelengths of the five combined products are all located at 330 nm.The scattered intensity increments (△I) of the combined products are directly proportional to the concentrations of the antibiotics in a certain range.The methods exhibit high sensitivity, and the detection limits for the five penicillin antibiotics are between 4.61 and 5.62 ng·mL-1.The spectral characteristics of RRS and the optimum reaction conditions were investigated.The mechanism of reaction and the reasons for the enhancement of resonance light scattering were discussed.The effects of coexisting substances have been examined, and the results indicated that the method had a good selectivity.It can be applied to the determination of penicillin antibiotics in capsule, tablet, human serum and urine samples.

  12. Highly sensitive electromembrane extraction for the determination of volatile organic compound metabolites in dried urine spot.

    Science.gov (United States)

    Suh, Joon Hyuk; Eom, Han Young; Kim, Unyong; Kim, Junghyun; Cho, Hyun-Deok; Kang, Wonjae; Kim, Da Som; Han, Sang Beom

    2015-10-16

    Electromembrane extraction coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for determination of ten volatile organic compound metabolites in dried urine spot samples. The dried urine spot approach is a convenient and economical sampling method, wherein urine is spotted onto a filter paper and dried. This method requires only a small amount of sample, but the analysis sometimes suffers from low sensitivity, which can lead to analytical problems in the detection of minor components in samples. The newly developed dried urine spot analysis using electromembrane extraction exhibited improved sensitivity and extraction, and enrichment of the sample was rapidly achieved in one step by applying an electric field. Aliquots of urine were spotted onto Bond Elut DMS cards and dried at room temperature. After drying, the punched out dried urine spot was eluted with water. Volatile organic compound metabolites were extracted from the sample through a supported liquid membrane into an alkaline acceptor solution inside the lumen of a hollow fiber with the help of an electric potential. The optimum extraction conditions were determined by using design of experiments (fractional factorial design and response surface methodology). Satisfactory sensitivity was achieved and the limits of quantification (LOQ) obtained were lower than the regulatory threshold limits. The method was validated by assessing the linearity, precision, accuracy, recovery, reproducibility, stability, and matrix effects. The results were acceptable, and the developed method was successfully applied to biological exposure monitoring of volatile organic compound metabolites in fifty human urine samples.

  13. Highly sensitive and selective spectrophotometric and spectrofluorimetric methods for the determination of ropinirole hydrochloride in tablets

    Science.gov (United States)

    Aydoğmuş, Zeynep

    2008-06-01

    Three sensitive, selective, accurate spectrophotometric and spectrofluorimetric methods have been developed for the determination of ropinirole hydrochloride in tablets. The first method was based on measuring the absorbance of drug solution in methanol at 250 nm. The Beer's law was obeyed in the concentration range 2.5-24 μg ml -1. The second method was based on the charge transfer reaction of drug, as n-electron donor with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as π-acceptor in acetonitrile to give radical anions that are measured at 842 nm. The Beer's law was obeyed in the concentration range 0.6-8 μg ml -1. The third method was based on derivatization reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 8.5 followed by measuring the fluorescence intensity at 525 nm with excitation at 464 nm in chloroform. Beer's law was obeyed in the concentration range 0.01-1.3 μg ml -1. The derivatization reaction product of drug with NBD-Cl was characterized by IR, 1H NMR and mass spectroscopy. The developed methods were validated. The following analytical parameters were investigated: the molar absorptivity ( ɛ), limit of detection (LOD, μg ml -1) and limit of quantitation (LOQ, μg ml -1), precision, accuracy, recovery, and Sandell's sensitivity. Selectivity was validated by subjecting stock solution of ropinirole to acidic, basic, oxidative, and thermal degradation. No interference was observed from common excipients present in formulations. The proposed methods were successfully applied for determination of drug in tablets. The results of these proposed methods were compared with each other statistically.

  14. Development of two highly sensitive forensic sex determination assays based on human DYZ1 and Alu repetitive DNA elements.

    Science.gov (United States)

    Fazi, Amanda; Gobeski, Brianne; Foran, David

    2014-11-01

    Sex determination is a critical component of forensic identification, the standard genetic method for which is detection of the single copy amelogenin gene that has differing homologues on the X and Y chromosomes. However, this assay may not be sensitive enough when DNA samples are minute or highly compromised, thus other strategies for sex determination are needed. In the current research, two ultrasensitive sexing assays, based on real-time PCR and pyrosequencing, were developed targeting the highly repetitive elements DYZ1 on the Y chromosome and Alu on the autosomes. The DYZ1/Alu strategy was compared to amelogenin for overall sensitivity based on high molecular weight and degraded DNA, followed by assaying the sex of 34 touch DNA samples and DNA from 30 hair shafts. The real-time DYZ1/Alu assay proved to be approximately 1500 times more sensitive than its amelogenin counterpart based on high molecular weight DNA, and even more sensitive when sexing degraded DNA. The pyrosequencing DYZ1/Alu assay correctly sexed 26 of the touch DNAs, compared to six using amelogenin. Hair shaft DNAs showed equally improved sexing results using the DYZ1/Alu assays. Overall, both DYZ1/Alu assays were far more sensitive and accurate than was the amelogenin assay, and thus show great utility for sexing poor quality and low quantity DNA evidence.

  15. Fabrication of CuO nanoplatelets for highly sensitive enzyme-free determination of glucose

    Energy Technology Data Exchange (ETDEWEB)

    Wang Juan [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China); Zhang Weide, E-mail: zhangwd@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China)

    2011-09-01

    Highlights: > Adhered growth of CuO nanoplatelets on Cu foils. > Enzyme-free glucose sensor with very high sensitivity. > Excellent stability and good anti-interference ability. - Abstract: CuO nanoplatelets were grown on Cu foils by a one step, template free process. The structure and morphology of the CuO nanoplatelets were characterized by X-ray diffraction, scanning and transmission electron microscopy. The CuO nanoplatelets grown on Cu foil were integrated to be an electrode for glucose sensing. The electrocatalytic activity of the CuO nanoplatelets electrode for glucose in alkaline media was investigated by cyclic voltammetry and chronoamperometry. The electrode exhibits a sensitivity of 3490.7 {mu}A mM{sup -1} cm{sup -2} to glucose which is much higher than that of most reported enzyme-free glucose sensors and the linear range was obtained over a concentration up to 0.80 mM with a detection limit of 0.50 {mu}M (signal/noise = 3). Exhilaratingly, the electrode based on the CuO nanoplatelets is resistant against poisoning by chloride ion, and the interference from the oxidation of common interfering species, such as uric acid, ascorbic acid, dopamine and carbonhydrate compounds, can also be effectively avoided. Finally, the electrode was applied to analyze glucose concentration in human serum samples.

  16. A Highly Sensitive Multicommuted Flow Analysis Procedure for Photometric Determination of Molybdenum in Plant Materials without a Solvent Extraction Step

    OpenAIRE

    Felisberto G. Santos; Boaventura F. Reis

    2017-01-01

    A highly sensitive analytical procedure for photometric determination of molybdenum in plant materials was developed and validated. This procedure is based on the reaction of Mo(V) with thiocyanate ions (SCN−) in acidic medium to form a compound that can be monitored at 474 nm and was implemented employing a multicommuted flow analysis setup. Photometric detection was performed using an LED-based photometer coupled to a flow cell with a long optical path length (200 mm) to achieve high sensit...

  17. High-performance liquid chromatographic determination of memantine hydrochloride in rat plasma using sensitive fluorometric derivatization.

    Science.gov (United States)

    Xie, Mei-Fen; Zhou, Wei; Tong, Xin-Yi; Chen, Yi-Le; Cai, Yi; Li, Yan; Duan, Geng-Li

    2011-02-01

    In this study, we investigated a simple, sensitive and reliable liquid chromatography-fluorescence detection method for the determination of memantine hydrochloride in rat plasma which was based on derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). For the first time, FMOC-Cl was introduced into derivatization of memantine hydrochloride in rat plasma. The amino groups of memantine hydrochloride and amantadine hydrochloride (internal standard) were trapped with FMOC-Cl to form memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions, which can be very compatible for LC-FLD. Precipitation of plasma proteins by acetonitrile was followed by vortex mixing and centrifugation. Chromatographic separation was performed on a C(18) column (DIAMONSIL 150 × 4.6 mm, id 5 μm) with a mobile phase consisting of acetonitrile and water at a flow rate of 1.0 mL/min. The retention times of memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions were 23.69 and 40.27 min, respectively. Optimal conditions for the derivatization of memantine hydrochloride were also described. The limit of quantification (LOQ) was 25 ng/mL for memantine hydrochloride in plasma, the linear range was 0.025-5.0 μg/mL in plasma with a correlation coefficient (r) of 0.9999. The relative standard deviations (RSDs) of intra-day and inter-day assays were 4.46-12.19 and 5.23-11.50%, respectively. The validated method was successfully applied to the determination of memantine hydrochloride in rat plasma samples.

  18. Based on magnetic graphene oxide highly sensitive and selective imprinted sensor for determination of sunset yellow.

    Science.gov (United States)

    Li, Jianbo; Wang, Xiaojiao; Duan, Huimin; Wang, Yanhui; Bu, Yanan; Luo, Chuannan

    2016-01-15

    A new imprinted material based on β-cyclodextrin/ionic liquid/gold nanoparticles functionalized magnetic graphene oxide has been successfully synthesized and modified to the glassy carbon electrode surface to constructed imprinted electrochemical sensor to detect sunset yellow. The sensitivity and electrochemical response of the electrode can be improved by nanomaterials. The surface morphology and crystal structure of the hybrid nanomaterial has been characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy. The electrochemical behaviors of the hybrid nanomaterials based sensor were evaluated through cyclic voltammetry and electrochemical impedance spectroscopy. Under the optimized conditions, the proposed electrochemical sensor showed a fast rebinding dynamics, which was successfully applied to sunset yellow detection with a wide linear range from 5.0×10(-9) to 2.0×10(-6)mol L(-1) and a detection limit of 2.0×10(-9)mol L(-1). The electrochemical sensor has been successfully applied in the determination of SY in spiked water samples, mirinda drink and minute maid, and the recoveries for the standards added are 97-105%.

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

    Science.gov (United States)

    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.

  20. Sensitive determination of specific radioactivity of positron emission tomography radiopharmaceuticals by radio high-performance liquid chromatography with fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Ryuji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)], E-mail: nakaor@nirs.go.jp; Furutsuka, Kenji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Sumitomo Accelerator Service, Tokyo 141-8686 (Japan); Yamaguchi, Masatoshi [Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka 814-0180 (Japan); Suzuki, Kazutoshi [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)

    2008-10-15

    A sensitive quality control method is often required in positron emission tomography (PET) radiopharmaceutical analysis due to the high specific radioactivity of synthetic products. The applicability of a radio high-performance liquid chromatography (HPLC) method with fluorescence detection was evaluated for a wide variety of PET radiopharmaceuticals. In 29 different radiopharmaceuticals studied, 20 compounds exhibited native fluorescence. These properties enabled sensitive determination of their chemical masses by direct fluorimetric detection after separation by HPLC. For some substances, detection limits were below nanograms per milliliter level, at least 40 times better than current UV absorbance detection. Sufficient reproducibility and linearity were obtained for the analysis of pharmaceutical fluid. Post-column fluorimetric derivatization was also established for the quantitative determination of FDG and ClDG in [{sup 18}F]FDG samples. These methods could be applied successfully to the analysis of PET radiopharmaceuticals with ultra-high specific radioactivity.

  1. Determining contrast sensitivity functions for monochromatic light emitted by high-brightness LEDs

    Science.gov (United States)

    Ramamurthy, Vasudha; Narendran, Nadarajah; Freyssinier, Jean Paul; Raghavan, Ramesh; Boyce, Peter

    2004-01-01

    Light-emitting diode (LED) technology is becoming the choice for many lighting applications that require monochromatic light. However, one potential problem with LED-based lighting systems is uneven luminance patterns. Having a uniform luminance distribution is more important in some applications. One example where LEDs are becoming a viable alternative and luminance uniformity is an important criterion is backlighted monochromatic signage. The question is how much uniformity is required for these applications. Presently, there is no accepted metric that quantifies luminance uniformity. A recent publication proposed a method based on digital image analysis to quantify beam quality of reflectorized halogen lamps. To be able to employ such a technique to analyze colored beams generated by LED systems, it is necessary to have contrast sensitivity functions (CSFs) for monochromatic light produced by LEDs. Several factors including the luminance, visual field size, and spectral power distribution of the light affect the CSFs. Although CSFs exist for a variety of light sources at visual fields ranging from 2 degrees to 20 degrees, CSFs do not exist for red, green, and blue light produced by high-brightness LEDs at 2-degree and 10-degree visual fields and at luminances typical for backlighted signage. Therefore, the goal of the study was to develop a family of CSFs for 2-degree and 10-degree visual fields illuminated by narrow-band LEDs at typical luminances seen in backlighted signs. The details of the experiment and the results are presented in this manuscript.

  2. Highly sensitive electrochemical determination of Sunset Yellow based on gold nanoparticles/graphene electrode

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jin; Yang, Beibei; Wang, Huiwen; Yang, Ping; Du, Yukou, E-mail: duyk@suda.edu.cn

    2015-09-17

    An electrochemical sensor was prepared using Au nanoparticles and reduced graphene successfully decorated on the glassy carbon electrode (Au/RGO/GCE) through an electrochemical method which was applied to detect Sunset Yellow (SY). The as-prepared electrode was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemical measurements. The results of cyclic voltammetry (CV) proved that Au/RGO/GCE had the highest catalytic activity for the oxidation of SY as compared with GCE, Au/GCE, and RGO/GCE. Differential pulse voltammetry (DPV) showed that the linear calibration curves for SY on Au/RGO/GCE in the range of 0.002 μM–109.14 μM, and the detection limit was estimated to be 2 nM (S/N = 3). These results suggested that the obtained Au/RGO/GCE was applied to detect SY with high sensitivity, low detection limit and good stability, which provided a promising future for the development of portable sensor in food additives. - Highlights: • An Au/RGO composite was fabricated by electrochemical deposition method. • The oxidation current of SY on the composition is up to 10 μA. • The detection range of SY is 0.002–109.14 μM with a detection limit of 2 nM.

  3. Zwitterionic Surfactant Modified Acetylene Black Paste Electrode for Highly Facile and Sensitive Determination of Tetrabromobisphenol A

    Directory of Open Access Journals (Sweden)

    Xiaoyun Wei

    2016-09-01

    Full Text Available A electrochemical sensor for the highly sensitive detection of tetrabromobisphenol A (TBBPA was fabricated based on acetylene black paste electrode (ABPE modified with 3-(N,N-Dimethylpalmitylammonio propanesulfonate (SB3-16 in this study. The peak current of TBBPA was significantly enhanced at SB3-16/ABPE compared with unmodified electrodes. To further improve the electrochemical performance of the modified electrode, corresponding experimental parameters such as the length of hydrophobic chains of zwitterionic surfactant, the concentration of SB3-16, pH value, and accumulation time were examined. The peak currents of TBBPA were found to be linearly correlated with its concentrations in the range of 1 nM to 1 µM, with a detection limit of 0.4 nM. Besides, a possible mechanism was also discussed, and the hydrophobic interaction between TBBPA and the surfactants was suggested to take a leading role in enhancing the responses. Finally, this sensor was successfully employed to detect TBBPA in water samples.

  4. Zwitterionic Surfactant Modified Acetylene Black Paste Electrode for Highly Facile and Sensitive Determination of Tetrabromobisphenol A

    Science.gov (United States)

    Wei, Xiaoyun; Zhao, Qiang; Wu, Weixiang; Zhou, Tong; Jiang, Shunli; Tong, Yeqing; Lu, Qing

    2016-01-01

    A electrochemical sensor for the highly sensitive detection of tetrabromobisphenol A (TBBPA) was fabricated based on acetylene black paste electrode (ABPE) modified with 3-(N,N-Dimethylpalmitylammonio) propanesulfonate (SB3-16) in this study. The peak current of TBBPA was significantly enhanced at SB3-16/ABPE compared with unmodified electrodes. To further improve the electrochemical performance of the modified electrode, corresponding experimental parameters such as the length of hydrophobic chains of zwitterionic surfactant, the concentration of SB3-16, pH value, and accumulation time were examined. The peak currents of TBBPA were found to be linearly correlated with its concentrations in the range of 1 nM to 1 µM, with a detection limit of 0.4 nM. Besides, a possible mechanism was also discussed, and the hydrophobic interaction between TBBPA and the surfactants was suggested to take a leading role in enhancing the responses. Finally, this sensor was successfully employed to detect TBBPA in water samples. PMID:27657078

  5. A highly sensitive quantitative real-time pcr assay for determination of mutant jak2 exon 12 allele burden

    DEFF Research Database (Denmark)

    Kjær, L.; Riley, C.H.; Westman, M.

    2012-01-01

    present a highly sensitive real-time quantitative PCR assay for determination of the mutant allele burden of JAK2 exon 12 mutations. In combination with high resolution melting analysis and sequencing the assay identified six patients carrying previously described JAK2 exon 12 mutations and one novel...... mutation. Two patients were homozygous with a high mutant allele burden, whereas one of the heterozygous patients had a very low mutant allele burden. The allele burden in the peripheral blood resembled that of the bone marrow, except for the patient with low allele burden. Myeloid and lymphoid cell...... populations were isolated by cell sorting and quantitative PCR revealed similar mutant allele burdens in CD16+ granulocytes and peripheral blood. The mutations were also detected in B-lymphocytes in half of the patients at a low allele burden. In conclusion, our highly sensitive assay provides an important...

  6. Highly selective and sensitive determination of copper ion by two novel optical sensors

    Directory of Open Access Journals (Sweden)

    Mehrorang Ghaedi

    2017-05-01

    Full Text Available New optical sensors for the determination of copper ion by incorporation of 1,1′-(4-nitro-1,2-phenylenebis(azan-1-yl-1-ylidenebis(methan-1-yl-1-lidenedinaphthalen-2-ol(L1, 1,1′-2,2′-(1,2-phenylenebis(ethene-2,1-diyldinaphthalen-2-ol 1(L2, dibutylphthalate (DBP and sodium tetraphenylborate (Na-TPB to the plasticized polyvinyl chloride matrices were prepared. The tendency of both ionophores (L2 and L1 as chromoionophore was significantly enhanced by the addition of DBP to the membrane. The proposed sensors benefit from advantages such as high stability, reproducibility and relatively long lifetime, good selectivity for Cu2+ ion determination over a large number of alkali, alkaline earth, transition and heavy metal ions. At optimum values of membrane compositions and experimental conditions, both sensors’ response was linear over a concentration range of 7.98 × 10−6 to 1.31 × 10−4mol L−1 and 1.99 × 10−6 to 5.12 × 10−5 mol L−1 for L2 and L1, respectively. Sensor detection limit based on the definition that the concentration of the sample leads to a signal equal to the blank signal plus three times of its standard deviation was found to be 3.99 × 10−7 and 5.88 × 10−7 mol L−1 for L2 and L1, respectively. The response time of the optodes (defined as the time required reaching the 90% of the peak signal was found to be 5–8 min for L2 and 20–25 min for L1 based sensor. The proposed optical sensors were applied successfully for the determination of Cu2+ ion content in water samples.

  7. A Highly Sensitive Multicommuted Flow Analysis Procedure for Photometric Determination of Molybdenum in Plant Materials without a Solvent Extraction Step.

    Science.gov (United States)

    Santos, Felisberto G; Reis, Boaventura F

    2017-01-01

    A highly sensitive analytical procedure for photometric determination of molybdenum in plant materials was developed and validated. This procedure is based on the reaction of Mo(V) with thiocyanate ions (SCN(-)) in acidic medium to form a compound that can be monitored at 474 nm and was implemented employing a multicommuted flow analysis setup. Photometric detection was performed using an LED-based photometer coupled to a flow cell with a long optical path length (200 mm) to achieve high sensitivity, allowing Mo(V) determination at a level of μg L(-1) without the use of an organic solvent extraction step. After optimization of operational conditions, samples of digested plant materials were analyzed employing the proposed procedure. The accuracy was assessed by comparing the obtained results with those of a reference method, with an agreement observed at 95% confidence level. In addition, a detection limit of 9.1 μg L(-1), a linear response (r = 0.9969) over the concentration range of 50-500 μg L(-1), generation of only 3.75 mL of waste per determination, and a sampling rate of 51 determinations per hour were achieved.

  8. A Highly Sensitive Multicommuted Flow Analysis Procedure for Photometric Determination of Molybdenum in Plant Materials without a Solvent Extraction Step

    Directory of Open Access Journals (Sweden)

    Felisberto G. Santos

    2017-01-01

    Full Text Available A highly sensitive analytical procedure for photometric determination of molybdenum in plant materials was developed and validated. This procedure is based on the reaction of Mo(V with thiocyanate ions (SCN− in acidic medium to form a compound that can be monitored at 474 nm and was implemented employing a multicommuted flow analysis setup. Photometric detection was performed using an LED-based photometer coupled to a flow cell with a long optical path length (200 mm to achieve high sensitivity, allowing Mo(V determination at a level of μg L−1 without the use of an organic solvent extraction step. After optimization of operational conditions, samples of digested plant materials were analyzed employing the proposed procedure. The accuracy was assessed by comparing the obtained results with those of a reference method, with an agreement observed at 95% confidence level. In addition, a detection limit of 9.1 μg L−1, a linear response (r=0.9969 over the concentration range of 50–500 μg L−1, generation of only 3.75 mL of waste per determination, and a sampling rate of 51 determinations per hour were achieved.

  9. A highly sensitive quantitative real-time PCR assay for determination of mutant JAK2 exon 12 allele burden.

    Directory of Open Access Journals (Sweden)

    Lasse Kjær

    Full Text Available Mutations in the Janus kinase 2 (JAK2 gene have become an important identifier for the Philadelphia-chromosome negative chronic myeloproliferative neoplasms. In contrast to the JAK2V617F mutation, the large number of JAK2 exon 12 mutations has challenged the development of quantitative assays. We present a highly sensitive real-time quantitative PCR assay for determination of the mutant allele burden of JAK2 exon 12 mutations. In combination with high resolution melting analysis and sequencing the assay identified six patients carrying previously described JAK2 exon 12 mutations and one novel mutation. Two patients were homozygous with a high mutant allele burden, whereas one of the heterozygous patients had a very low mutant allele burden. The allele burden in the peripheral blood resembled that of the bone marrow, except for the patient with low allele burden. Myeloid and lymphoid cell populations were isolated by cell sorting and quantitative PCR revealed similar mutant allele burdens in CD16+ granulocytes and peripheral blood. The mutations were also detected in B-lymphocytes in half of the patients at a low allele burden. In conclusion, our highly sensitive assay provides an important tool for quantitative monitoring of the mutant allele burden and accordingly also for determining the impact of treatment with interferon-α-2, shown to induce molecular remission in JAK2V617F-positive patients, which may be a future treatment option for JAK2 exon 12-positive patients as well.

  10. Highly sensitive determination of copper in HeLa cell using capillary electrophoresis combined with a simple cell extraction treatment.

    Science.gov (United States)

    Meng, Lingchen; Fang, Ziyuan; Lin, Jian; Li, Meixian; Zhu, Zhiwei

    2014-04-01

    A new separation system of capillary electrophoresis (CE1) for the highly sensitive determination of copper was established by using ethylenediaminetetraacetic acid (EDTA) as a complexing agent and employing cetyltrimethylammonium chloride (CTAC) as a capillary inner wall modifier. Benefitted from the combination of field-enhanced sample injection (FESI) method, a limit of detection (LOD) of 2.7 nM was obtained, which was much lower than that of the conventional methods. This made it possible to determine trace copper in HeLa cell only by a simple cell extraction (CE2) treatment. Two copper-extraction methods-acid-hydrolysis and freeze-thaw-were compared. Limited by the requirement of low ion strength in FESI, only the extract using freeze-thaw could be successfully applied in the determination. The effectiveness assessment of this CE(2)-FESI method was adopted by inductively coupled plasma-atomic emission spectrometry (ICP-AES) as a gold standard.

  11. Highly sensitive fluorescence optode based on polymer inclusion membranes for determination of Al(III) ions.

    Science.gov (United States)

    Suah, F B M; Ahmad, M; Heng, L Y

    2014-07-01

    This paper reports the use of a polymer inclusion membranes (PIMs) for direct determination of Al(III) ions in natural water by using a fluorescence based optode. The best composition of the PIMs consisted of 60 wt.% (m/m) poly (vinyl chloride) (PVC) as the base polymer, 20 wt.% (m/m) triton X-100 as an extractant, 20 wt.% (m/m) dioctyl phthalate (DOP) as plasticizer and morin as the reagent, was used in this study. The inclusion of triton X-100 was used for enhancing the sorption of Al(III) ions from liquid phase into the membrane phase, thus increasing the optode fluorescence intensity. The optimized optode was characterized by a linear calibration curve in the range from 7.41 × 10(-7) to 1.00 × 10(-4) molL(-1) of Al(III), with a detection limit of 5.19 × 10(-7) molL(-1). The response of the optode was 4 min and reproducible results were obtained for eight different membranes demonstrated good membrane stability. The optode was applied to the determination of Al(III) in natural water samples. The result obtained is comparable to atomic absorption spectrometry method.

  12. Highly sensitive covalently functionalized light-addressable potentiometric sensor for determination of biomarker.

    Science.gov (United States)

    Liang, Jintao; Guan, Mingyuan; Huang, Guoyin; Qiu, Hengming; Chen, Zhengcheng; Li, Guiyin; Huang, Yong

    2016-06-01

    A biomarker is related to the biological status of a living organism and shows great promise for the early prediction of a related disease. Herein we presented a novel structured light-addressable potentiometric sensor (LAPS) for the determination of a model biomarker, human immunoglobulin G (hIgG). In this system, the goat anti-human immunoglobulin G antibody was used as recognition element and covalently immobilized on the surface of light-addressable potentiometric sensor chip to capture human immunoglobulin G. Due to the light addressable capability of light-addressable potentiometric sensor, human immunoglobulin G dissolved in the supporting electrolyte solution can be detected by monitoring the potential shifts of the sensor. In order to produce a stable photocurrent, the laser diode controlled by field-programmable gate array was used as the light emitter to drive the light-addressable potentiometric sensor. A linear correlation between the potential shift response and the concentration of human immunoglobulin G was achieved and the corresponding regression equation was ΔV (V)=0.00714ChIgG (μg/mL)-0.0147 with a correlation coefficient of 0.9968 over a range 0-150 μg/mL. Moreover, the light-addressable potentiometric sensor system also showed acceptable stability and reproducibility. All the results demonstrated that the system was more applicable to detection of disease biomarkers with simple operation, multiple-sample format and might hold great promise in various environmental, food, and clinical applications.

  13. A Validated High-Throughput Fluorometric Method for Determination of Omeprazole in Quality Control Laboratory via Charge Transfer Sensitized Fluorescence.

    Science.gov (United States)

    Mahmoud, Ashraf M; Ahmed, Sameh A

    2016-03-01

    A high-throughput 96-microwell plate fluorometric method was developed and validated to determine omeprazole (OMZ) in its dosage forms. The method was based on the charge-transfer (CT) sensitized fluorescence reaction of OMZ with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ). This fluorescence reaction provided a new approach for simple, sensitive and selective determinations of OMZ in pharmaceutical preparations. In the present method, the fluorescence reaction was carried out in 96-microwell plates as reaction vessels in order to increase the automation of the methodology and the efficiency of its use in quality control laboratories. All factors affecting the fluorescence reaction were carefully studied and the conditions were optimized. The stoichiometry of the fluorescence reaction between OMZ and DDQ was determined and the reaction mechanism was suggested. Under the optimum conditions, the linear range was 100-6000 ng/ml with the lowest LOD of 33 ng/ml. Analytical performance of the proposed assay, in terms of accuracy and precision, was statistically validated and the results were satisfactory; RSD was <2.6 % and the accuracy was 98.6-101.6 %. The method was successfully applied to the analysis of OMZ in its dosage forms; the recovery values were 98.26-99.60 ± 0.95-2.22 %. The developed methodology may provide a safer, automated and economic tool for the analysis of OMZ in quality control laboratories.

  14. Highly sensitive determination of mercury using copper enhancer by diamond electrode coupled with sequential injection–anodic stripping voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Chaiyo, Sudkate [Department of Chemistry, Faculty of Science, Srinakharinwirot University (Thailand); Chailapakul, Orawon [Department of Chemistry, Faculty of Science, Chulalongkorn University (Thailand); Center for Petroleum, Petrochemicals, and Advanced Materials, Chulalongkorn University (Thailand); Siangproh, Weena, E-mail: weena@swu.ac.th [Department of Chemistry, Faculty of Science, Srinakharinwirot University (Thailand)

    2014-12-10

    Highlights: • Highly sensitive determination of Hg(II) using SI–ASV-BDD was achieved. • Electrochemical detection of Hg(II) using Cu(II) enhancer was accomplished. • LOD and LOQ were found to be very low at 40.0 ppt and 135.0 ppt. • This method was successfully applied for determination of Hg(II) in real samples. - Abstract: A highly sensitive determination of mercury in the presence of Cu(II) using a boron-doped diamond (BDD) thin film electrode coupled with sequential injection–anodic stripping voltammetry (SI–ASV) was proposed. The Cu(II) was simultaneously deposited with Hg(II) in a 0.5 M HCl supporting electrolyte by electrodeposition. In presence of an excess of Cu(II), the sensitivity for the determination of Hg(II) was remarkably enhanced. Cu(II) and Hg(II) were on-line deposited onto the BDD electrode surface at −1.0 V (vs. Ag/AgCl, 3 M KCl) for 150 s with a flow rate of 14 μL s{sup −1}. An anodic stripping voltammogram was recorded from −0.4 V to 0.25 V using a frequency of 60 Hz, an amplitude of 50 mV, and a step potential of 10 mV at a stopped flow. Under the optimal conditions, well-defined peaks of Cu(II) and Hg(II) were found at −0.25 V and +0.05 V (vs. Ag/AgCl, 3 M KCl), respectively. The detection of Hg(II) showed two linear dynamic ranges (0.1–30.0 ng mL{sup −1} and 5.0–60.0 ng mL{sup −1}). The limit of detection (S/N = 3) obtained from the experiment was found to be 0.04 ng mL{sup −1}. The precision values for 10 replicate determinations were 1.1, 2.1 and 2.9% RSD for 0.5, 10 and 20 ng mL{sup −1}, respectively. The proposed method has been successfully applied for the determination of Hg(II) in seawater, salmon, squid, cockle and seaweed samples. A comparison between the proposed method and an inductively coupled plasma optical emission spectrometry (ICP-OES) standard method was performed on the samples, and the concentrations obtained via both methods were in agreement with the certified values of Hg

  15. Highly sensitive and selective electrochemical determination of dopamine and ascorbic acid at Ag/Ag{sub 2}S modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chen-Yan [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Cai, Ying-Jie [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Yang, Chien-Hsin [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan (China); Wu, Chen-Hao [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Wei, Yen [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Department of Chemistry, Drexel University, Philadelphia, PA 19104 (United States); Wen, Ten-Chin, E-mail: tcwen@mail.ncku.edu.t [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Wang, Tzong-Liu; Shieh, Yeong-Tarng [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan (China); Lin, Wen-Churng [Department of Environmental Engineering, Kun Shan University, Tainan 71016, Taiwan (China); Chen, Wen-Janq [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan (China)

    2011-02-01

    A biosensor electrode possessing highly sensitive and selective determination of dopamine (DA) is fabricated. This electrode, a silver (Ag) thin film on indium-tin-oxide glass, is treated with a silver sulfide (Ag{sub 2}S) film using electrochemical deposition. Active Ag ion is easier to form on Ag{sub 2}S than on pristine Ag, which prefers to attract ascorbic acid (AA). The Ag{sub 2}S layer reduces the oxidation potential of AA due to the electrostatic interaction, which results in well-separation of mixed oxidation responses to both of DA and AA. Besides, the Ag{sub 2}S-modified electrode exhibits dramatic electrocatalytic effect on the oxidation of DA in the presence of AA. In 0.1 M phosphate buffer solution at pH {approx} 7.0, the differential pulse voltammetric peak intensity linearly correlates with DA concentration in two regions, viz. 1.0-10, and 10-100 {mu}M, with correlation coefficient of 0.998 and 0.995, respectively. The lowest concentration limit of 1.0 {mu}M DA can be detected. The interference of AA effectively diminishes in the mixed solution. These features make the Ag{sub 2}S significant for selective and sensitive measurement of DA in the presence of excess AA.

  16. A highly sensitive fluorimetric method for determination of lenalidomide in its bulk form and capsules via derivatization with fluorescamine

    Directory of Open Access Journals (Sweden)

    Darwish Ibrahim A

    2012-10-01

    Full Text Available Abstract Background Lenalidomide (LND is a potent novel thalidomide analog which demonstrated remarkable clinical activity in treatment of multiple myeloma disease via a multiple-pathways mechanism. The strong evidences-based clinical success of LND in patients has led to its recent approval by US-FDA under the trade name of Revlimid® capsules by Celgene Corporation. Fluorimetry is a convenient technique for pharmaceutical quality control, however there was a fluorimetric method for determination of LND in its bulk and capsules. Results A novel highly sensitive and simple fluorimetric method has been developed and validated for the determination of lenalidmide (LND in its bulk and dosage forms (capsules. The method was based on nucleophilic substitution reaction of LND with fluorescamine (FLC in aqueous medium to form a highly fluorescent derivative that was measured at 494 nm after excitation at 381 nm. The factors affecting the reaction were carefully studied and optimized. The kinetics of the reaction was investigated, and the reaction mechanism was postulated. Under the optimized conditions, linear relationship with good correlation coefficient (0.9999 was found between the fluorescence intensity and LND concentration in the range of 25–300 ng/mL. The limits of detection and quantitation for the method were 2.9 and 8.7 ng/mL, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 1.4%. The proposed method was successfully applied to the determination of LND in its bulk form and pharmaceutical capsules with good accuracy; the recovery values were 97.8–101.4 ± 1.08–2.75%. Conclusions The proposed method is selective and involved simple procedures. In conclusion, the method is practical and valuable for routine application in quality control laboratories for determination of LND.

  17. Highly sensitive determination of fatty acid esters of hydroxyl fatty acids by liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Zhu, Quan-Fei; Yan, Jing-Wen; Gao, Yang; Zhang, Jing-Wei; Yuan, Bi-Feng; Feng, Yu-Qi

    2017-09-01

    Recently, a new class of endogenous lipids, branched fatty acid esters of hydroxy fatty acids (FAHFAs), was discovered with anti-diabetic and anti-inflammatory effects in mammals. FAHFAs attracted increasing attention because of their critical physiological function. However, accurate quantitation of FAHFAs is still a challenge due to their high structure similarity and low abundance in biological samples. Herein, we developed a highly sensitive method for the determination of 16 FAHFAs (PAHSAs, OAHSAs, SAHSAs and POHSAs) in biological samples by coupling strong anion exchange solid phase extraction (SAX-SPE) with chemical labeling assisted ultra-high performance liquid chromatography/mass spectrometry (SAX-SPE-CL-UHPLC/MS). In the developed method, SAX-SPE was employed to selectively enrich and purify FAHFAs from biological samples. And then a pair of isotope labeling reagents, 2-dimethylaminoethylamine (DMED) and d4-DMED were used to label the purified samples and standard FAHFAs, respectively. The labeled samples were mixed and further subjected to UHPLC/MS analysis. Our results demonstrated that the detection sensitivities of FAHFAs increased by 7-72 folds upon DMED labeling and the limits of detections (LODs) of labeled FAHFAs ranged from 0.01 to 0.14pg. Moreover, a good separation of FAHFAs isomers was achieved on C18 column in a UHPLC system and all FAHFAs could be analyzed in 20min with sharp peak shape. The established method provided substantial sensitivity, high specificity, and broad linear dynamic range (3 orders of magnitude). Using this method, we successfully measured the contents and distribution of FAHFAs in rat white adipose, lung, kidney, thymus, liver and heart tissues. The results showed that 7 FAHFAs (13-, 12-, 9-, 5-PAHSA, 13-, 12- and 9-SAHSA) were observed in different tissues of rat. In addition, we successfully detected the above 7 FAHFAs in human serum samples; and among the 7 FAHFAs, 13-, 9-PAHSA, 13- and 12-SAHSA were found remarkably

  18. Assessing manganese nanostructures based carbon nanotubes composite for the highly sensitive determination of vitamin C in pharmaceutical formulation.

    Science.gov (United States)

    Hameed, Sadaf; Munawar, Anam; Khan, Waheed S; Mujahid, Adnan; Ihsan, Ayesha; Rehman, Asma; Ahmed, Ishaq; Bajwa, Sadia Z

    2017-03-15

    This work is the first report describing the development of a novel three dimensional manganese nanostructures based carbon nanotubes (CNTs-Mn NPs) composite, for the determination of ascorbic acid (vitamin C) in pharmaceutical formulation. Carbon nanotubes (CNTs) were used as a conductive skeleton to anchor highly electrolytic manganese nanoparticles (Mn NPs), which were prepared by a hydrothermal method. Scanning electron microscopy and atomic force microscopy revealed the presence of Mn Nps of 20-25nm, anchored along the whole length of CNTs, in the form of patches having a diameter of 50-500nm. Fourier transform infrared spectroscopy confirmed the surface modification of CNTs by amine groups, whereas dynamic light scattering established the presence of positive charge on the prepared nanocomposite. The binding events were studied by monitoring cyclic voltammetry signals and the developed nanosensor exhibited highly sensitive response, demonstrating improved electrochemical activity towards ascorbic acid. Linear dependence of the peak current on the square root of scan rates (R(2)=0.9785), demonstrated that the oxidation of ascorbic acid by the designed nanostructures is a diffusion control mechanism. Furthermore, linear range was found to be 0.06-4.0×10(-3)M, and nanosensor displayed an excellent detection limit of 0.1µM (S/N=3). This developed nanosensor was successfully applied for the determination of vitamin C in pharmaceutical formulation. Besides, the results of the present study indicate that such a sensing platform may offer a different pathway to utilize manganese nanoparticles based CNTs composite for the determination of other bio-molecules as well.

  19. High sensitive and selective HPTLC method assisted by digital image processing for simultaneous determination of catecholamines and related drugs.

    Science.gov (United States)

    Sima Tuhuţiu, Ioana Anamaria; Casoni, Dorina; Sârbu, Costel

    2013-09-30

    A highly sensitive and selective thin layer chromatographic (TLC) method was developed for simultaneous determination of catecholamines and their related drugs using a new detection method and digital image processing of chromatographic plates. For the quantitative evaluation of the investigated compounds, the chromatographic separation was followed by spraying the plate with 0.02% solution of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) in ethanol. The BioDit Thin Layer Chromatography (TLC) Scanner device and advanced specific software (ImageDecipher-TLC, Sorbfil TLC Videodensitometer and JustTLC) were used for the detection and quantification of chromatographic spots. For an accurate determination, the RGB colored images of the bright-white spots detected against a purple background were inverted and processed after their conversion into green scale. The results showed a strongly linear correlation between area (R(2)>0.99) and volume (R(2)>0.99) of spots and concentration of investigated compounds in all cases. The limit of detection (LOD) and the limit of quantification (LOQ) were below 49.3 ng/spot and 69.6 ng/spot respectively in all cases. The evaluation of the method was performed using different pharmaceutical samples spiked with the investigated amines and validated with respect to accuracy and precision.

  20. High-Sensitivity Spectrophotometry.

    Science.gov (United States)

    Harris, T. D.

    1982-01-01

    Selected high-sensitivity spectrophotometric methods are examined, and comparisons are made of their relative strengths and weaknesses and the circumstances for which each can best be applied. Methods include long path cells, noise reduction, laser intracavity absorption, thermocouple calorimetry, photoacoustic methods, and thermo-optical methods.…

  1. Highly Sensitive Optical Receivers

    CERN Document Server

    Schneider, Kerstin

    2006-01-01

    Highly Sensitive Optical Receivers primarily treats the circuit design of optical receivers with external photodiodes. Continuous-mode and burst-mode receivers are compared. The monograph first summarizes the basics of III/V photodetectors, transistor and noise models, bit-error rate, sensitivity and analog circuit design, thus enabling readers to understand the circuits described in the main part of the book. In order to cover the topic comprehensively, detailed descriptions of receivers for optical data communication in general and, in particular, optical burst-mode receivers in deep-sub-µm CMOS are presented. Numerous detailed and elaborate illustrations facilitate better understanding.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Lintong; Cheng, Qin [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, Danchao; Ma, Ming [Ningbo Entry-exit Inspection and Quarantine Bureau of China, Ningbo 315012 (China); Wu, Kangbing, E-mail: kbwu@hust.edu.cn [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-02-11

    Graphical abstract: - Highlights: • A novel electrochemical sensor was developed for diethylstilbestrol and estradiol. • Graphene prepared by solvent exfoliation greatly enhances the detection sensitivity. • The newly-developed method has promising application and the accuracy is good. - Abstract: 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 0.28 V and 0.49 V 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.

  3. Sensitive determination of 4-O-methylhonokiol in rabbit plasma by high performance liquid chromatography and application

    Institute of Scientific and Technical Information of China (English)

    Ming-Yue Li; Yu-Hai Tang; Xia Liu; Hai-Yan Lu; Xi-Yan Shi

    2011-01-01

    A novel high performance liquid chromatographic method was developed for the determination of 4-O- methylhonokiol in rabbit plasma and was applied to its pharmacokinetic investigation. Plasma samples were treated by one-fold volume of methanol and acetoni

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

    Science.gov (United States)

    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.

  5. High-sensitivity microchip electrophoresis determination of inorganic anions and oxalate in atmospheric aerosols with adjustable selectivity and conductivity detection.

    Science.gov (United States)

    Noblitt, Scott D; Schwandner, Florian M; Hering, Susanne V; Collett, Jeffrey L; Henry, Charles S

    2009-02-27

    A sensitive and selective separation of common anionic constituents of atmospheric aerosols, sulfate, nitrate, chloride, and oxalate, is presented using microchip electrophoresis. The optimized separation is achieved in under 1 min and at low background electrolyte ionic strength (2.9 mM) by combining a metal-binding electrolyte anion (17 mM picolinic acid), a sulfate-binding electrolyte cation (19 mM HEPBS), a zwitterionic surfactant with affinity towards weakly solvated anions (19 mM N-tetradecyl,N,N-dimethyl-3-ammonio-1-propansulfonate), and operation in counter-electroosmotic flow (EOF) mode. The separation is performed at pH 4.7, permitting pH manipulation of oxalate's mobility. The majority of low-concentration organic acids are not observed at these conditions, allowing for rapid subsequent injections without the presence of interfering peaks. Because the mobilities of sulfate, nitrate, and oxalate are independently controlled, other minor constituents of aerosols can be analyzed, including nitrite, fluoride, and formate if desired using similar separation conditions. Contact conductivity detection is utilized, and the limit of detection for oxalate (S/N=3) is 180 nM without stacking. Sensitivity can be increased with field-amplified sample stacking by injecting from dilute electrolyte with a detection limit of 19 nM achieved. The high-sensitivity, counter-EOF operation, and short analysis time make this separation well-suited to continuous online monitoring of aerosol composition.

  6. Rapid and sensitive high performance liquid chromatographic determination of zonisamide in human serum application to a pharmacokinetic study

    Directory of Open Access Journals (Sweden)

    M B Majnooni

    2012-01-01

    Full Text Available An accurate and very rapid method for determination of zonisamide an antiepileptic drug, in human serum is described. The analytical procedure involves liquid-liquid extraction of the analyte and an internal standard (vanillin from human serum by ethyl acetate as extracting solvent. Chromatographic separation was achieved using a monolithic C18 analytical column and a mixture of 0.05 M phosphate buffer containing triethylamine (1 ml/l; pH 2.7 and methanol (83:17 v/v was used as the mobile phase. The detection wavelength was set at 240 nm. The calibration curve was linear over a concentration range of 0.015-6.4 μg/ml of zonisamide in human serum. The total run time of analysis was 3.5 min and the lower limits of detection and quantification were 0.005 and 0.015 μg/ml, respectively. The method validation was carried out in terms of specificity, sensitivity, linearity, precision, accuracy and stability. The validated method was applied in a randomised crossover bioequivalence study of two different zonisamide preparations in 24 healthy volunteers, and the assay was sensitive enough to measure drug levels up to 8 days following a single dose administration of zonisamide.

  7. Electropolymerized poly(Toluidine Blue)-modified carbon felt for highly sensitive amperometric determination of NADH in flow injection analysis

    Institute of Scientific and Technical Information of China (English)

    Yasushi Hasebe; Yue Wang; Kazuya Fukuoka

    2011-01-01

    Poly(pheniothiazine) films were prepared on a porous carbon felt (CF) electrode surface by an electrooxidative polymerization of three phenothiazine derivatives (i.e.,Tthionine (TN), Toluidine Blue (TB) and Methylene Blue (MB)) from 0.1 mol/L phosphate buffer solution (pH 7.0).Among the three phenothiazies, the poly(TB) film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form (NADH) at +0.2 V vs.Ag/AgCl.The poly(TB) film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH.The peak currents (peak heights) were almost unchanged, irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min, resulting in the measurement of NADH (ca.30 samples/hr) at 4.1 mL/min.The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 μmol/L (sensitivity: 0.318 μA/(μmol/L); correlation coefficient: 0.997).The lower detection limit was found to be 0.3 μmol/L (S/N = 3).

  8. Generation of polyclonal antibody with high avidity to rosuvastatin and its use in development of highly sensitive ELISA for determination of rosuvastatin in plasma

    Directory of Open Access Journals (Sweden)

    Al-Malaq Hamoud A

    2011-07-01

    Full Text Available Abstract In this study, a polyclonal antibody with high avidity and specificity to the potent hypocholesterolaemic agent rosuvastatin (ROS has been prepared and used in the development of highly sensitive enzyme-linked immunosorbent assay (ELISA for determination of ROS in plasma. ROS was coupled to keyhole limpt hemocyanin (KLH and bovine serum albumin (BSA using carbodiimide reagent. ROS-KLH conjugate was used for immunization of female 8-weeks old New Zealand white rabbits. The immune response of the rabbits was monitored by direct ELISA using ROS-BSA immobilized onto microwell plates as a solid phase. The rabbit that showed the highest antibody titer and avidity to ROS was scarified and its sera were collected. The IgG fraction was isolated and purified by avidity chromatography on protein A column. The purified antibody showed high avidity to ROS; IC50 = 0.4 ng/ml. The specificity of the antibody for ROS was evaluated by indirect ELISA using various competitors from the ROS-structural analogues and the therapeutic agents used with ROS in a combination therapy. The proposed ELISA involved a competitive binding reaction between ROS, in plasma sample, and the immobilized ROS-BSA for the binding sites on a limited amount of the anti-ROS antibody. The bound anti-ROS antibody was quantified with horseradish peroxidase-labeled second anti-rabbit IgG antibody (HRP-IgG and 3,3',5,5'-tetramethylbenzidine (TMB as a substrate for the peroxidase enzyme. The concentration of ROS in the sample was quantified by its ability to inhibit the binding of the anti-ROS antibody to the immobilized ROS-BSA and subsequently the color intensity in the assay wells. The assay enabled the determination of ROS in plasma at concentrations as low as 40 pg/ml.

  9. Full evaporation headspace gas chromatography for sensitive determination of high boiling point volatile organic compounds in low boiling matrices.

    Science.gov (United States)

    Mana Kialengila, Didi; Wolfs, Kris; Bugalama, John; Van Schepdael, Ann; Adams, Erwin

    2013-11-08

    Determination of volatile organic components (VOC's) is often done by static headspace gas chromatography as this technique is very robust and combines easy sample preparation with good selectivity and low detection limits. This technique is used nowadays in different applications which have in common that they have a dirty matrix which would be problematic in direct injection approaches. Headspace by nature favors the most volatile compounds, avoiding the less volatile to reach the injector and column. As a consequence, determination of a high boiling solvent in a lower boiling matrix becomes challenging. Determination of VOCs like: xylenes, cumene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI), benzyl alcohol (BA) and anisole in water or water soluble products are an interesting example of the arising problems. In this work, a headspace variant called full evaporation technique is worked out and validated for the mentioned solvents. Detection limits below 0.1 μg/vial are reached with RSD values below 10%. Mean recovery values ranged from 92.5 to 110%. The optimized method was applied to determine residual DMSO in a water based cell culture and DMSO and DMA in tetracycline hydrochloride (a water soluble sample). Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Sensitive determination of Amaranth in drinks by highly dispersed CNT in graphene oxide "water" with the aid of small amounts of ionic liquid.

    Science.gov (United States)

    Wang, Meiling; Sun, Yinlu; Yang, Xiongbo; Zhao, Jianwei

    2015-07-15

    Graphene oxide (GO) is a pH-dependent amphiphile. In this paper, it was found that carbon nanotubes (CNTs) can be highly dispersed in graphene oxide "water" with the aid of prototype ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). The introduction of [BMIM][PF6] not only can minimize the defects of poor electrical conductivity of GO, but also can improve the dispersibility of CNT in water. Hence, a new composite of CNT/GO-[BMIM][PF6] with high dispersibility and strong conductivity was presented for the first time and employed in the sensitive determination of Amaranth in soft drinks. The detection limit achieved (0.1 nM) is much lower than the guideline values in soft drinks. The ease of preparation, low background current, high sensitivity and stability can create novel avenues and applications for fabricating robust sensors for determination of other azo dyes in foods.

  11. Rapid and sensitive determination of carbohydrates in foods using high temperature liquid chromatography with evaporative light scattering detection.

    Science.gov (United States)

    Terol, Amanda; Paredes, Eduardo; Maestre, Salvador E; Prats, Soledad; Todolí, José L

    2012-04-01

    In the present work, an evaporative light scattering detector was used as a high-temperature liquid chromatography detector for the determination of carbohydrates. The compounds studied were glucose, fructose, galactose, sucrose, maltose, and lactose. The effect of column temperature on the retention times and detectability of these compounds was investigated. Column heating temperatures ranged from 25 to 175°C. The optimum temperature in terms of peak resolution and detectability with pure water as mobile phase and a liquid flow rate of 1 mL/min was 150°C as it allowed the separation of glucose and the three disaccharides here considered in less than 3 min. These conditions were employed for lactose determination in milk samples. Limits of quantification were between 2 and 4.7 mg/L. On the other hand, a temperature gradient was developed for the simultaneous determination of glucose, fructose, and sucrose in orange juices, due to coelution of monosaccharides at temperatures higher than 70°C, being limits of quantifications between 8.5 and 12 mg/L. The proposed hyphenation was successfully applied to different types of milk and different varieties of oranges and mandarins. Recoveries for spiked samples were close to 100% for all the studied analytes.

  12. A simple, sensitive determination of ganciclovir in infant plasma by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Yoshida, Terumitsu; Takahashi, Ryohei; Imai, Koichi; Uchida, Hiroshi; Arai, Yasutoshi; Oh-ishi, Tsutomu

    2010-03-01

    This study developed a simple and sensitive method using reversed-phase high-performance liquid chromatography (HPLC) for ganciclovir (GCV) plasma concentrations in cytomegalovirus infectious infants with hearing loss. The method involves a simple protein precipitation procedure that uses no solid-phase or liquid-liquid extraction. The HPLC separation was carried out on a Cadenza CD-C(18) column (3 microm, 4.6 mm x 150 mm) with phosphate buffer (pH 2.5, 25 mM) containing 1% methanol-acetonitrile mixture (4:3, v/v) as a mobile phase at a 0.7 mL/min flow rate. GCV was detected using a fluorescence detection (lambdaex/em: 265/380 nm). The quantification limit was 0.025 microg/mL for 100 microL of plasma sample at which good intra- and inter-assay coefficient of variation values (< 4.96%) and recoveries (94.9-96.5%) were established.

  13. Ultra-High Sensitivity Techniques for the Determination of 3 He /4 He Abundances in Helium by Accelerator Mass Spectrometry

    Science.gov (United States)

    Mumm, H. P.; Huber, M.; Bauder, W.; Abrams, N.; Deibel, C.; Huffer, C.; Huffman, P.; Schelhammer, K.; Janssens, R.; Jiang, C.; Scott, R.; Pardo, R.; Rehm, K.; Vondrasek, R.; Swank, C.; O'Shaughnessy, C.; Paul, M.; Yang, L.

    2017-01-01

    We report the development of an Accelerator Mass Spectrometry technique to measure the 3He/4He isotopic ratio using a radio frequency (RF) discharge source and the ATLAS facility at Argonne National Laboratory. Control over 3He/4He ratio in helium several orders of magnitude lower than natural abundance is critical for neutron lifetime and source experiments using liquid helium. Due to low ultimate beam currents, the ATLAS accelerator and beam line were tuned using a succession of species of the same M/q. A unique RF source was developed for the experiment due to large natural 3He backgrounds. Analog H_3 + and DH + molecular ions are eliminated by dissociation via a gold stripper foil near the detector. The stripped ions were dispersed in a magnetic spectrograph and 3He2 + ions counted in the focal plane detector. This technique is sensitive to 3 He /4 He ratios in the regime of 10-12 with backgrounds that appear to be below 10-14. The techniques used to reduce the backgrounds and remaining outstanding problems will be presented along with results from measurements on high purity 4He samples.

  14. Highly sensitive amperometric biosensor based on electrochemically-reduced graphene oxide-chitosan/hemoglobin nanocomposite for nitromethane determination.

    Science.gov (United States)

    Wen, Yunping; Wen, Wei; Zhang, Xiuhua; Wang, Shengfu

    2016-05-15

    Nitromethane (CH3NO2) is an important organic chemical raw material with a wide variety of applications as well as one of the most common pollutants. Therefore it is pretty important to establish a simple and sensitive detection method for CH3NO2. In our study, a novel amperometric biosensor for nitromethane (CH3NO2) based on immobilization of electrochemically-reduced graphene oxide (rGO), chitosan (CS) and hemoglobin (Hb) on a glassy carbon electrode (GCE) was constructed. Scanning electron microscopy, infrared spectroscopy and electrochemical methods were used to characterize the Hb-CS/rGO-CS composite film. The effects of scan rate and pH of phosphate buffer on the biosensor have been studied in detail and optimized. Due to the graphene and chitosan nanocomposite, the developed biosensor demonstrating direct electrochemistry with faster electron-transfer rate (6.48s(-1)) and excellent catalytic activity towards CH3NO2. Under optimal conditions, the proposed biosensor exhibited fast amperometric response (biosensor had high selectivity, reproducibility and stability, providing the possibility for monitoring CH3NO2 in complex real samples.

  15. High sensitive C-reactive protein-Effective tool in determining postoperative recovery in lumbar disc disease

    Directory of Open Access Journals (Sweden)

    Tushar Narayan Rathod

    2014-01-01

    Full Text Available Background: It is common in medical practice to see patients having persistent pain and radiculopathy even after undergoing discectomy surgery. Inflammatory cytokines, such as interleukins are produced at the site of disc herniation and are now considered responsible for the pain perceived by the patient. This study has used high sensitive C-reactive protein (HSCRP assay for predicting inflammation around the nerve roots on very same principle, which has used HSCRP for predicting coronary artery diseases in current clinical practice. Thus, purpose of this study is to test whether HSCRP can stand as an objective tool to predict postoperative recovery in patients undergoing lumbar discectomy. That is, to study association between preoperative HSCRP blood level and postoperative recovery with the help of modified Oswestry Back Disability Score. Materials and Methods: A study group consisting of 50 cases of established lumbar disc disease and control group of 50 normal subjects, matched with the study group. Both the study and control groups were subjected to detailed evaluation with the help of modified Oswestry Low Back Pain Scale both pre and postoperatively at 3 months, 6 months and 1-year. The preoperative blood samples were analyzed to assess the HSCRP concentration. All the cases underwent surgery over a period of 1-year by the same surgeon. Results: The level of HSCRP in the study group was between 0.050- and 0.710 mg/dL and in the control group, 0.005-0.020 mg/dL. There was highly significant positive correlation between preoperative HSCRP level and postoperative score at P 10 points, while those with HSCRP level in the range of 0.470 ± 0.163 mg/dL, showed poor recovery (score improved < 10 points. Conclusion: HSCRP will serve as a good supplementary prognostic marker for operative decision making in borderline and troublesome cases of lumbar disc disease.

  16. A Highly Sensitive Electrochemical DNA Biosensor from Acrylic-Gold Nano-composite for the Determination of Arowana Fish Gender

    Science.gov (United States)

    Rahman, Mahbubur; Heng, Lee Yook; Futra, Dedi; Chiang, Chew Poh; Rashid, Zulkafli A.; Ling, Tan Ling

    2017-08-01

    The present research describes a simple method for the identification of the gender of arowana fish ( Scleropages formosus). The DNA biosensor was able to detect specific DNA sequence at extremely low level down to atto M regimes. An electrochemical DNA biosensor based on acrylic microsphere-gold nanoparticle (AcMP-AuNP) hybrid composite was fabricated. Hydrophobic poly(n-butylacrylate-N-acryloxysuccinimide) microspheres were synthesised with a facile and well-established one-step photopolymerization procedure and physically adsorbed on the AuNPs at the surface of a carbon screen printed electrode (SPE). The DNA biosensor was constructed simply by grafting an aminated DNA probe on the succinimide functionalised AcMPs via a strong covalent attachment. DNA hybridisation response was determined by differential pulse voltammetry (DPV) technique using anthraquinone monosulphonic acid redox probe as an electroactive oligonucleotide label (Table 1). A low detection limit at 1.0 × 10-18 M with a wide linear calibration range of 1.0 × 10-18 to 1.0 × 10-8 M ( R 2 = 0.99) can be achieved by the proposed DNA biosensor under optimal conditions. Electrochemical detection of arowana DNA can be completed within 1 hour. Due to its small size and light weight, the developed DNA biosensor holds high promise for the development of functional kit for fish culture usage.

  17. Highly Sensitive Spectrofluorimetric Determination of Riboflavin Based on the Generation of Active Oxygen Coupled with Enzymatic Reaction

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A spectrofluorimetric method for the determining riboflavin (VB2) based on its enhancement on the fluorescence of hemoglobin-catalyzed enzymatic reaction was proposed. The proposed method consisted of two reactions. One was the photochemical reaction of VB2, the other was a hemoglobin-catalyzed enzymatic reaction. The optimal experimental conditions for the determinations were established. The linear range of the method was 5.0×10-9-1.0×10-7mol/L of VB2. The detection limit was calculated to be 3.65×10-9 mol/L. The relative standard deviation of this method was 2.3 % at 7.0×10-8 mol/L for 11 determinations.

  18. High-Sensitivity Magnetization Measurements

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The three most common instruments for high-sensitivity magnetization measurements (the vibrating-sample magnetometer, the alternating gradient magnetometer, and the SQUID magne tometer) are described and their limiting sensitivities are discussed. The advantages and disad vantages of each are described. Magnetometers using micro-machined force detectors are briefly mentioned.

  19. Characteristics of DNA-binding proteins determine the biological sensitivity to high-linear energy transfer radiation

    NARCIS (Netherlands)

    H. Wang (Hong); X. Zhang (Xiangming); P. Wang (Ping); X. Yu (Xiaoyan); J. Essers (Jeroen); D.J. Chen (David); R. Kanaar (Roland); S. Takeda (Shiunichi); Y. Wang (Ya)

    2010-01-01

    textabstractNon-homologous end-joining (NHEJ) and homologous recombination repair (HRR), contribute to repair ionizing radiation (IR)-induced DNA double-strand breaks (DSBs). Mre11 binding to DNA is the first step for activating HRR and Ku binding to DNA is the first step for initiating NHEJ. High-l

  20. Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Berton, Paula [Analytical Chemistry Research and Development Group (QUIANID), (LISAMEN - CCT - CONICET - Mendoza), Av. Ruiz Leal S/N Parque General San Martin, M 5502 IRA Mendoza (Argentina); Wuilloud, Rodolfo G., E-mail: rwuilloud@mendoza-conicet.gov.ar [Analytical Chemistry Research and Development Group (QUIANID), (LISAMEN - CCT - CONICET - Mendoza), Av. Ruiz Leal S/N Parque General San Martin, M 5502 IRA Mendoza (Argentina); Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza (Argentina)

    2010-03-10

    A simple and rapid dispersive liquid-liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C{sub 6}mim][PF{sub 6}] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co-1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng L{sup -1}, while the relative standard deviation (RSD) was 3.4% (at 1 {mu}g L{sup -1} Co level and n = 10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples.

  1. Highly Sensitive Fluorescence Methods for the Determination of Alfuzosin, Doxazosin, Terazosin and Prazosin in Pharmaceutical Formulations, Plasma and Urine.

    Science.gov (United States)

    Guo, Xiaozhen; Wu, Hao; Guo, Shiwen; Shi, Yating; DU, Juanli; Zhu, Panpan; DU, Liming

    2016-01-01

    Polymeric ionic liquid-coated magnetic nanoparticles have been successfully prepared as adsorbents for the magnetic solid-phase extraction of four drugs, namely alfuzosin, doxazosin, terazosin and prazosin, from pharmaceutical preparations, urine samples and plasma samples. The four drugs were detected by fluorescence spectrophotometer. Several extraction parameters, including the pH of the solution; the type, ratio and volume of the desorbing reagent; the amount of adsorbent; the time of the extraction and desorption processes; and the addition of NaCl, were investigated and optimized. Linear responses were determined for the four drugs in the concentration range of 0.5 - 45 ng mL(-1). The limit of detection values for alfuzosin, doxazosin, terazosin and prazosin, which were defined as three times the standard deviation of a blank sample, were determined to be 0.035, 0.034, 0.027 and 0.028 ng mL(-1) (n = 11), respectively. Furthermore, this new method gave preconcentration factors of 114.5, 111.3, 111.1 and 108.5 for these four drugs.

  2. Highly sensitive derivatization reagents possessing positively charged structures for the determination of oligosaccharides in glycoproteins by high-performance liquid chromatography electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Min, Jun Zhe; Nagai, Keisuke; Shi, Qing; Zhou, Wenjun; Todoroki, Kenichiro; Inoue, Koichi; Lee, Yong-Ill; Toyo'oka, Toshimasa

    2016-09-23

    We have developed three kinds of novel derivatization reagents (4-CEBTPP, 4-CBBTPP, 5-COTPP) with triphenylphosphine (TPP) as a basic structure carrying a permanent positive charge for resolution of the oligosaccharides in glycoprotein using high-performance liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The synthesized reagents reacted with the sialylglycosylamine of the sialylglycopeptide after treatment by PNGase F. The final derivatives were analyzed by ESI-MS and sensitively detected in the selected reaction monitoring (SRM) mode. Furthermore, the limits of detection (S/N=3) on the SRM chromatograms were at the fmol level (30fmol). Therefore, we used the limit of detection of the reagent products detected by the SRM and evaluated the utility of each reagent. Among the reagents, the positively charged 4-CEBTPP derivative's peak area was the highest; 4-CEBTPP with a positively charged structure showed about a 20 times greater sensitivity for the glycosylamine of the SGP product compared to the conventional fluorescence reagent, Fmoc-Cl. In addition, various fragment ions based on the carbohydrate units also appeared in the MS/MS spectra. Among the fragment ions, m/z 627.37 (CE=40eV) corresponding to 4-CEBTPP-GlcNAc and m/z 120.09 (CE=100eV) corresponding to 4-CEBTPP are the most important ones for identifying the oligosaccharide. 4-CEBTPP-SGA was easily identified by the selected-ion chromatogram in the product ion scan (m/z 120.09) and in the precursor ion scan (m/z 627.37) by MS/MS detection. The derivatized analytes have a high ionization efficiency and they are detected with a high sensitivity in the electrospray ionization. The novel derivatization reagent with a multi-function provided a higher sensitivity for the oligosaccharide analysis, as well as a better specificity and feasibility. Furthermore, several oligosaccharides in fetuin and ribonuclease B were successfully identified by the proposed procedure.

  3. Highly selective and sensitive determination of several antioxidants in human breast milk using high-performance liquid chromatography based on Ag(III) complex chemiluminescence detection.

    Science.gov (United States)

    Ma, Li; Shi, Hongmei; Lian, Kaoqi; Diao, Yingfei; Chen, Yang; Ma, Chunling; Kang, Weijun

    2017-03-01

    Ascorbic acid (AA), uric acid (UA) and glutathione (GSH) are the most important water-soluble antioxidants. The concentrations of GSH and glutathione disulfide (GSSG) and their molar ratio are the indicators of oxidative stress. Little is known about the contents of UA, GSH and GSSG in human milk; a reliable and sensitive method to monitor the concentrations of the four compounds simultaneously in human milk is of critical importance. A new method for separation and quantification of these water-soluble antioxidants by HPLC coupled with Ag(III) chemiluminescence detector has been developed in this work with better recoveries. The antioxidants contents were determined in different times of lactation utilizing this method. The results show that the levels of AA, UA, GSH and GSH/GSSG of human colostrum are significantly higher than those of mature milk (Pantioxidants than mature milk. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. A purified MAA-based ELISA is a useful tool for determining anti-MAA antibody titer with high sensitivity

    Science.gov (United States)

    Shimomoto, Takasumi; Collins, Leonard B.; Yi, Xianwen; Holley, Darcy W.; Zhang, Zhenfa; Tian, Xu; Uchida, Koji; Wang, Chunguang; Hörkkö, Sohvi; Willis, Monte S.; Gold, Avram; Bultman, Scott J.; Nakamura, Jun

    2017-01-01

    Atherosclerosis is widely accepted to be a chronic inflammatory disease, and the immunological response to the accumulation of LDL is believed to play a critical role in the development of this disease. 1,4-Dihydropyridine-type MAA-adducted LDL has been implicated in atherosclerosis. Here, we have demonstrated that pure MAA-modified residues can be chemically conjugated to large proteins without by-product contamination. Using this pure antigen, we established a purified MAA-ELISA, with which a marked increase in anti-MAA antibody titer was determined at a very early stage of atherosclerosis in 3-month ApoE-/- mice fed with a normal diet. Our methods of Nε-MAA-L-lysine purification and purified antigen-based ELISA will be easily applicable for biomarker-based detection of early stage atherosclerosis in patients, as well as for the development of an adduct-specific Liquid Chromatography/Mass Spectrometry-based quantification of physiological and pathological levels of MAA. PMID:28222187

  5. Glassy carbon electrodes modified with a film of nanodiamond-graphite/chitosan: Application to the highly sensitive electrochemical determination of Azathioprine

    Energy Technology Data Exchange (ETDEWEB)

    Shahrokhian, Saeed, E-mail: shahrokhian@sharif.ed [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of); Institute for Nanoscience and Technology, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Ghalkhani, Masoumeh [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of)

    2010-04-15

    A novel modified glassy carbon electrode with a film of nanodiamond-graphite/chitosan is constructed and used for the sensitive voltammetric determination of azathioprine (Aza). The surface morphology and thickness of the film modifier are characterized using atomic force microscopy. The electrochemical response characteristics of the electrode toward Aza are investigated by means of cyclic voltammetry. The modified electrode showed an efficient catalytic role for the electrochemical reduction of Aza, leading to a remarkable decrease in reduction overpotential and enhancement of the kinetics of the electrode reaction with a significant increase of peak current. The effects of experimental variables, such as the deposited amount of modifier suspension, the pH of the supporting electrolyte, the accumulation potential and time were investigated. Under optimal conditions, the modified electrode showed a wide linear response to the concentration of Aza in the range of 0.2-100 muM with a detection limit of 65 nM. The prepared modified electrode showed several advantages: simple preparation method, high stability and uniformity in the composite film, high sensitivity, excellent catalytic activity in physiological conditions and good reproducibility. The modified electrode can be successfully applied to the accurate determination of trace amounts of Aza in pharmaceutical and clinical preparations.

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

    Directory of Open Access Journals (Sweden)

    Burcu Gumuscu

    Full Text Available 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.

  7. High-performance liquid chromatographic method for sensitive determination of the alkylating agent CB1954 in human plasma.

    Science.gov (United States)

    Anderson, D; Ferry, D R; Knox, R J; Andrews, S J; Downes, A J; Kerr, D J; Seymour, L W

    1999-08-20

    A high-performance liquid chromatography (HPLC) method is described for the measurement of the weak alkylating agent CB1954 in human plasma. CB1954 can be used as an innocuous prodrug designed for activation by bacterial nitroreductases in strategies of gene-directed enzyme-prodrug therapy, and becomes activated to a potent bifunctional alkylating agent. The HPLC method involves precipitation and solvent extraction and uses Mitomycin C (MMC) as an internal standard, with a retention time for MMC of 5.85 +/- 0.015 min, and for CB1954 of 10.72 +/- 0.063 min. The limit of detection for CB1954 is 2.9 ng/ml, and this compares favourably with systems involving direct analysis of plasma (limit of detection 600 ng/ml, approximately). The method is now being used for pharmacokinetic measurements in plasma samples from cancer patients entering phase I clinical trials of CB1954. Results using serial plasma samples from one patient are presented. The patient was treated intravenously with CB1954 (6 mg/m2), and plasma clearance of the drug showed biphasic kinetics with alpha half-life 14.6 min, and beta half-life 170.5 min.

  8. Sensitive determination of melamine in milk and powdered infant formula samples by high-performance liquid chromatography using dabsyl chloride derivatization followed by dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Faraji, M; Adeli, M

    2017-04-15

    A new and sensitive pre-column derivatization with dabsyl chloride followed by dispersive liquid-liquid microextraction was developed for the analysis of melamine (MEL) in raw milk and powdered infant formula samples by high performance liquid chromatography (HPLC) with visible detection. Derivatization with dabsyl chloride leads to improving sensitivity and hydrophobicity of MEL. Under optimum conditions of derivatization and microextraction steps, the method yielded a linear calibration curve ranging from 1.0 to 500μgL(-1) with a determination coefficient (R(2)) of 0.9995. Limit of detection and limit of quantification were 0.1 and 0.3μgL(-1), respectively. The relative standard deviation (RSD%) for intra-day (repeatability) and inter-day (reproducibility) at 25 and 100μgL(-1) levels of MEL was less than 7.0% (n=6). Finally, the proposed method was successfully applied for the preconcentration and determination of MEL in different raw milk and powdered infant formula, and satisfactory results were obtained (relative recovery ⩾94%).

  9. High Sensitivity deflection detection of nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Sanii, Babak; Ashby, Paul

    2009-10-28

    A critical limitation of nanoelectromechanical systems (NEMS) is the lack of a high-sensitivity position detection mechanism. We introduce a noninterferometric optical approach to determine the position of nanowires with a high sensitivity and bandwidth. Its physical origins and limitations are determined by Mie scattering analysis. This enables a dramatic miniaturization of detectable cantilevers, with attendant reductions to the fundamental minimum force noise in highly damping environments. We measure the force noise of an 81{+-}9??nm radius Ag{sub 2}Ga nanowire cantilever in water at 6{+-}3??fN/{radical}Hz.

  10. 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.

    Science.gov (United States)

    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).

  11. Highly sensitive and specific determination of mercury(II) ion in water, food and cosmetic samples with an ELISA based on a novel monoclonal antibody

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuzhen; Li, Yuan [Sichuan University, College of Chemistry, Chengdu (China); Yang, Hong [Soochow University, College of Pharmacy, Suzhou (China); Pschenitza, Michael; Niessner, Reinhard; Knopp, Dietmar [Technical University Munich, Chair for Analytical Chemistry, Institute of Hydrochemistry and Chemical Balneology, Munich (Germany); Deng, Anping [Sichuan University, College of Chemistry, Chengdu (China); Soochow University, College of Chemistry, Chemical Engineering and Materials Science, Suzhou (China)

    2012-07-15

    Mercury is one of the most toxic heavy metals present in the environment. In this study, a highly sensitive and specific monoclonal antibody (mAb)-based indirect competitive enzyme-linked immunosorbent assay (ELISA) for the determination of Hg{sup 2+} was developed. A new bifunctional ligand, 6-mercaptonicotinic acid (MNA), which contains a pyridine ring bearing a carboxylic group and a mercapto group, was selected for the preparation of immunogen. After immunization of mice and performing the hybridoma technique, the obtained mAb was characterized for its binding affinity and selectivity for Hg{sup 2+}. Based on this novel mAb, an ELISA was established. At optimal experimental conditions, the standard curve of the ELISA for Hg{sup 2+} was constructed in concentration range of 0.1-100 ng mL{sup -1}. The values of IC{sub 50} and LOD of the assay were found to be 1.12 and 0.08 ng mL{sup -1}. The cross-reactivity was lower than 2 % with MNA, CH{sub 3}Hg, and CH{sub 3}Hg-MNA and was 11.5 % and 4.4 % for Hg{sup +} and Au{sup 3+}, respectively. No cross-reactivity was found with other metal ions such as Cu{sup 2+}, Sn{sup 2+}, Ni{sup 2+}, Mn{sup 2+}, Pb{sup 2+}, Zn{sup 2+}, Cd{sup 2+}, Fe{sup 2+}, Co{sup 2+}, Mg{sup 2+}, Ca{sup 2+}, and anions such as Cl{sup -}, NO{sub 3} {sup -}, NO{sub 2} {sup -}, HCO{sub 3} {sup -}, F{sup -}, and SO{sub 4} {sup 2-}, indicating that the assay displays not only high sensitivity but also high selectivity. Different kinds of samples including water, milk, green vegetable, kelp, facial cleanser, and night cream were spiked with Hg{sup 2+} and the extracts were analyzed by ELISA. Acceptable recovery rates of 80.0-113.0 % and coefficients of variation of 1.9-18.6 % were obtained. A linear relationship between ELISA and cold-vapor atomic fluorescence spectroscopy (CV-AFS) as indicated by a correlation coefficient of 0.97 for liquid samples (water samples) and 0.98 for other samples was obtained. The proposed mAb-based ELISA provides a

  12. High sensitivity RNA pseudoknot prediction.

    Science.gov (United States)

    Huang, Xiaolu; Ali, Hesham

    2007-01-01

    Most ab initio pseudoknot predicting methods provide very few folding scenarios for a given RNA sequence and have low sensitivities. RNA researchers, in many cases, would rather sacrifice the specificity for a much higher sensitivity for pseudoknot detection. In this study, we introduce the Pseudoknot Local Motif Model and Dynamic Partner Sequence Stacking (PLMM_DPSS) algorithm which predicts all PLM model pseudoknots within an RNA sequence in a neighboring-region-interference-free fashion. The PLM model is derived from the existing Pseudobase entries. The innovative DPSS approach calculates the optimally lowest stacking energy between two partner sequences. Combined with the Mfold, PLMM_DPSS can also be used in predicting complicated pseudoknots. The test results of PLMM_DPSS, PKNOTS, iterated loop matching, pknotsRG and HotKnots with Pseudobase sequences have shown that PLMM_DPSS is the most sensitive among the five methods. PLMM_DPSS also provides manageable pseudoknot folding scenarios for further structure determination.

  13. Ultrasound-assisted dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-fluorescence detection for sensitive determination of biogenic amines in rice wine samples.

    Science.gov (United States)

    Huang, Ke-Jing; Wei, Cai-Yun; Liu, Wei-Li; Xie, Wan-Zhen; Zhang, Jun-Feng; Wang, Wei

    2009-09-18

    Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography-fluorescence detection was used for the extraction and determination of three biogenic amines including octopamine, tyramine and phenethylamine in rice wine samples. Fluorescence probe 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester was applied for derivatization of biogenic amines. Acetonitrile and 1-octanol were used as disperser solvent and extraction solvent, respectively. Extraction conditions including the type of extraction solvent, the volume of extraction solvent, ultrasonication time and centrifuging time were optimized. After extraction and centrifuging, analyte was injected rapidly into high-performance liquid chromatography and then detected with fluorescence. The calibration graph of the proposed method was linear in the range of 5-500 microg mL(-1) (octopamine and tyramine) and 0.025-2.5 microg mL(-1) (phenethylamine). The relative standard deviations were 2.4-3.2% (n=6) and the limits of detection were in the range of 0.02-5 ng mL(-1). The method was applied to analyze the rice wine samples and spiked recoveries in the range of 95.42-104.56% were obtained. The results showed that ultrasound-assisted dispersive liquid-liquid microextraction was a very simple, rapid, sensitive and efficient analytical method for the determination of trace amount of biogenic amines.

  14. Highly selective and sensitive optical sensor for determination of Pb2+and Hg2+ ions based on the covalent immobilization of dithizone on agarose membrane

    Science.gov (United States)

    Zargoosh, Kiomars; Babadi, Fatemeh Farhadian

    2015-02-01

    A highly sensitive and selective optical membrane for determination of Hg2+ and Pb2+ was prepared by covalent immobilization of dithizone on agarose membrane. In addition to its high stability, reproducibility and relatively long lifetime, the proposed optical sensor revealed good selectivity for target ions over a large number of alkali, alkaline earth, transition, and heavy metal ions. The proposed optical membrane displays linear responses from 1.1 × 10-8 to 2.0 × 10-6 mol L-1 and 1.2 × 10-8 to 2.4 × 10-6 mol L-1 for Hg2+ and Pb2+, respectively. The limits of detection (LOD) were 2.0 × 10-9 mol L-1 and 4.0 × 10-9 mol L-1 for Hg2+ and Pb2, respectively. The prepared optical membrane was successfully applied to the determination of Hg2+ and Pb2+ in industrial wastes, spiked tap water and natural waters without any preconcentration step.

  15. High performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry for sensitive determination of bioactive amines in donkey milk.

    Science.gov (United States)

    La Torre, Giovanna Loredana; Saitta, Marcello; Giorgia Potortì, Angela; Di Bella, Giuseppa; Dugo, Giacomo

    2010-08-06

    In the present study we report on the optimization and validation of a sensitive high performance liquid chromatography atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS) method for the determination of 8 bioactive amines (histamine, tyramine, tryptamine, 2-phenylethylamine, cadaverine, putrescine, spermidine and spermine) in donkey milk samples. The method involves donkey milk pre-treatment to remove proteins and pre-column dansylation of the amines. HPLC in reversed phase mode has been used for bioactive amines separation and the operating condition of the APCI-MS system proved to be powerful and very efficient for peak assignment. The separation was accomplished in a short time with an excellent resolution for all the amine peaks. Quantification was carried out by monitoring the characteristic [M+H](+) ion of each amine derivative. The method sensitivity, linearity and repeatability were assayed with satisfactory results. The detection limits of the analysed amines ranged from 0.5 microg L(-1) to 15 microg L(-1); the highest LOD was for spermine. Also remarkably good recovery values were obtained; at the lowest spiking level (1 microg L(-1)) the percent mean recoveries ranged from 77.7 to 109.7. Furthermore, as the investigations relate to a complex matrix as donkey milk, suitable studies on matrix effect were performed. Finally, the developed and validated method was applied to analyse 13 donkey milk samples. Among the identified bioactive amines, putrescine, spermine and spermidine proved to be the main amines in donkey milk. Their concentration levels in the present study were lower than the values determined in mature human, cow and sow milk.

  16. A sensitive fluorescence reagent for the determination of aldehydes from alcoholic beverage using high-performance liquid chromatography with fluorescence detection and mass spectrometric identification

    Energy Technology Data Exchange (ETDEWEB)

    You Jinmao [Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xining 810001 (China)], E-mail: Jmyou6304@163.com; Yan Tao; Zhao Huaixin [Key Laboratory of Life-Organic Analysis, College of Chemistry Science, Qufu Normal University, Qufu Shandong 273165 (China); Sun Zhiwei; Xia Lian; Suo Yourui; Li Yulin [Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xining 810001 (China)

    2009-03-16

    A pre-column derivatization method for the sensitive determination of aldehydes using the tagging reagent 2-[2-(7H-dibenzo[a,g] carbazol-7-yl)-ethoxy] ethyl carbonylhydrazine (DBCEEC) followed by high-performance liquid chromatography with fluorescence detection and APCI-MS identification has been developed. The chromophore of fluoren-9-methoxy-carbonylhydrazine (Fmoc-hydrazine) reagent was replaced by 2-[2-(7H-dibenzo[a,g] carbazol-7-yl)-ethoxy] ethyl functional group, which resulted in a sensitive fluorescence tagging reagent DBCEEC. DBCEEC could easily and quickly labeled aldehydes. The maximum excitation (300 nm) and emission (400 nm) wavelengths did not essentially change for all the aldehyde derivatives. Derivatives were sufficiently stable to be efficiently analyzed by high-performance liquid chromatography. The derivatives showed an intense protonated molecular ion corresponding m/z [M + (CH{sub 2}){sub n}]{sup +} in positive-ion mode (M: molecular weight of DBCEEC, n: corresponding aldehyde carbon atom numbers). The collision-induced dissociation of protonated molecular ion formed fragment ions at m/z 294.6, m/z 338.6 and m/z 356.5. Studies on derivatization demonstrated excellent derivative yields in the presence of trichloroacetic acid (TCA) catalyst. Maximal yields close to 100% were observed with a 10 to 15-fold molar reagent excess. Separation of the derivatized aldehydes had been optimized on ZORBAX Eclipse XDB-C{sub 8} column with aqueous acetonitrile as mobile phase in conjunction with a binary gradient elution. Excellent linear responses were observed at the concentration range of 0.01-10 nmol mL{sup -1} with coefficients of >0.9991. Detection limits obtained by the analysis of a derivatized standard containing 0.01 nmol mL{sup -1} of each aldehyde, were from 0.2 to 1.78 nmol L{sup -1} (at a signal-to-noise ratio of 3)

  17. A sensitive fluorescence reagent for the determination of aldehydes from alcoholic beverage using high-performance liquid chromatography with fluorescence detection and mass spectrometric identification.

    Science.gov (United States)

    You, Jinmao; Yan, Tao; Zhao, Huaixin; Sun, Zhiwei; Xia, Lian; Suo, Yourui; Li, Yulin

    2009-03-16

    A pre-column derivatization method for the sensitive determination of aldehydes using the tagging reagent 2-[2-(7H-dibenzo[a,g] carbazol-7-yl)-ethoxy] ethyl carbonylhydrazine (DBCEEC) followed by high-performance liquid chromatography with fluorescence detection and APCI-MS identification has been developed. The chromophore of fluoren-9-methoxy-carbonylhydrazine (Fmoc-hydrazine) reagent was replaced by 2-[2-(7H-dibenzo[a,g] carbazol-7-yl)-ethoxy] ethyl functional group, which resulted in a sensitive fluorescence tagging reagent DBCEEC. DBCEEC could easily and quickly labeled aldehydes. The maximum excitation (300nm) and emission (400nm) wavelengths did not essentially change for all the aldehyde derivatives. Derivatives were sufficiently stable to be efficiently analyzed by high-performance liquid chromatography. The derivatives showed an intense protonated molecular ion corresponding m/z [M+(CH(2))(n)](+) in positive-ion mode (M: molecular weight of DBCEEC, n: corresponding aldehyde carbon atom numbers). The collision-induced dissociation of protonated molecular ion formed fragment ions at m/z 294.6, m/z 338.6 and m/z 356.5. Studies on derivatization demonstrated excellent derivative yields in the presence of trichloroacetic acid (TCA) catalyst. Maximal yields close to 100% were observed with a 10 to 15-fold molar reagent excess. Separation of the derivatized aldehydes had been optimized on ZORBAX Eclipse XDB-C(8) column with aqueous acetonitrile as mobile phase in conjunction with a binary gradient elution. Excellent linear responses were observed at the concentration range of 0.01-10nmolmL(-1) with coefficients of >0.9991. Detection limits obtained by the analysis of a derivatized standard containing 0.01nmolmL(-1) of each aldehyde, were from 0.2 to 1.78nmolL(-1) (at a signal-to-noise ratio of 3).

  18. Highly sensitive LC-MS/MS methods for the determination of seven human CYP450 activities using small oral doses of probe-drugs in human.

    Science.gov (United States)

    Grangeon, Alexia; Gravel, Sophie; Gaudette, Fleur; Turgeon, Jacques; Michaud, Veronique

    2017-01-01

    Cocktails composed of several Cytochrome P450 (CYP450)-selective probe drugs have been shown of value to characterize in vivo drug-metabolism activities. Our objective was to develop and validate highly sensitive and selective LC-MS/MS assays allowing the determination of seven major human CYP450 isoenzyme activities following administration of low oral doses of a modified CYP450 probe-drug cocktail in patients. The seven-drug cocktail was composed of caffeine, bupropion, tolbutamide, omeprazole, dextromethorphan, midazolam (all administered concomitantly) and chlorzoxazone (administered separately) to phenotype for CYP1A2, 2B6, 2C9, 2C19, 2D6, 3A4/5 and 2E1, respectively. Serial plasma and urine samples were collected over an 8h period. The probe-drugs and their respective metabolites were measured in both human plasma and urine, except for omeprazole (plasma only) and chlorzoxazone (urine only). Samples were analyzed by high performance liquid chromatography with heated electrospray ionization tandem mass spectrometry (HPLC-HESI-MS/MS) using a Phenomenex Luna PFP (2) analytical column (3μm PFP(2) 150×3mm) for chromatographic separation. Optimal detection was achieved based on 3 different analytical methods; (1) isocratic elution with a mobile phase consisting of acetonitrile and water both fortified with 0.01% formic acid for the analysis of bupropion, tolbutamide, chlorzoxazone and their respective metabolites; (2) isocratic elution with a mobile phase composed of acetonitrile and ammonium formate (pH 3; 10mM) for omeprazole, dextromethorphan, midazolam and their metabolites; (3) for caffeine and paraxanthine, gradient elution using acetonitrile and 0.01% formic acid in water was used. All calibration functions were linear for all probe drugs and metabolites in both matrices over wide analytical ranges. The main advantages of our methods are the use of specific probe drugs available in most countries, the administration of small doses of probe drugs, small

  19. Development of a Novel, Sensitive, Selective, and Fast Methodology to Determine Malondialdehyde in Leaves of Melon Plants by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Melisa E. Yonny

    2017-01-01

    Full Text Available Early production of melon plant (Cucumis melo is carried out using tunnels structures, where extreme temperatures lead to high reactive oxygen species production and, hence, oxidative stress. Malondialdehyde (MDA is a recognized biomarker of the advanced oxidative status in a biological system. Thus a reliable, sensitive, simple, selective, and rapid separative strategy based on ultra-high-performance liquid chromatography coupled to positive electrospray-tandem mass spectrometry (UPLC-(+ESI-MS/MS was developed for the first time to measure MDA, without derivatization, in leaves of melon plants exposed to stress conditions. The detection and quantitation limits were 0.02 μg·L−1 and 0.08 μg·L−1, respectively, which was demonstrated to be better than the methodologies currently reported in the literature. The accuracy values were between 96% and 104%. The precision intraday and interday values were 2.7% and 3.8%, respectively. The optimized methodology was applied to monitoring of changes in MDA levels between control and exposed to thermal stress conditions melon leaves samples. Important preliminary conclusions were obtained. Besides, a comparison between MDA levels in melon leaves quantified by the proposed method and the traditional thiobarbituric acid reactive species (TBARS approach was undertaken. The MDA determination by TBARS could lead to unrealistic conclusions regarding the oxidative stress status in plants.

  20. Development of a Novel, Sensitive, Selective, and Fast Methodology to Determine Malondialdehyde in Leaves of Melon Plants by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

    Science.gov (United States)

    Yonny, Melisa E.; Rodríguez Torressi, Ariel

    2017-01-01

    Early production of melon plant (Cucumis melo) is carried out using tunnels structures, where extreme temperatures lead to high reactive oxygen species production and, hence, oxidative stress. Malondialdehyde (MDA) is a recognized biomarker of the advanced oxidative status in a biological system. Thus a reliable, sensitive, simple, selective, and rapid separative strategy based on ultra-high-performance liquid chromatography coupled to positive electrospray-tandem mass spectrometry (UPLC-(+)ESI-MS/MS) was developed for the first time to measure MDA, without derivatization, in leaves of melon plants exposed to stress conditions. The detection and quantitation limits were 0.02 μg·L−1 and 0.08 μg·L−1, respectively, which was demonstrated to be better than the methodologies currently reported in the literature. The accuracy values were between 96% and 104%. The precision intraday and interday values were 2.7% and 3.8%, respectively. The optimized methodology was applied to monitoring of changes in MDA levels between control and exposed to thermal stress conditions melon leaves samples. Important preliminary conclusions were obtained. Besides, a comparison between MDA levels in melon leaves quantified by the proposed method and the traditional thiobarbituric acid reactive species (TBARS) approach was undertaken. The MDA determination by TBARS could lead to unrealistic conclusions regarding the oxidative stress status in plants. PMID:28203476

  1. Utility of Hantzsch reaction for development of highly sensitive spectrofluorimetric method for determination of alfuzosin and terazosin in bulk, dosage forms and human plasma.

    Science.gov (United States)

    Hammad, Mohamed A; Omar, Mahmoud A; Salman, Baher I

    2017-03-17

    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.

  2. Biosensor based on a silicon nanowire field-effect transistor functionalized by gold nanoparticles for the highly sensitive determination of prostate specific antigen.

    Science.gov (United States)

    Presnova, Galina; Presnov, Denis; Krupenin, Vladimir; Grigorenko, Vitaly; Trifonov, Artem; Andreeva, Irina; Ignatenko, Olga; Egorov, Alexey; Rubtsova, Maya

    2017-02-15

    We have demonstrated label-free and real-time detection of prostate specific antigen (PSA) in human serum using silicon nanowire field effect transistors (NW FETs) with Schottky contacts (Si-Ti). The NW FETs were fabricated from SOI material using high-resolution e-beam lithography, thin film vacuum deposition and reactive-ion etching processes eliminating complicated processes of doping and thermal annealing. This allowed substantial simplifying the transistors manufacturing. A new method for covalent immobilization of half-fragments of antibodies on silicon modified by 3-glycidopropyltrimethoxysilane with thiol groups and 5nm gold nanoparticles (GNPs) was established. NW FETs functionalized by GNPs revealed extremely high pH sensitivity of 70mV/pH and enhanced electrical performance in the detection of antigen due to enhanced surface/volume ratio, favorable orientation of antibody active sites and approaching the source of the electric field close to the transistor surface. Si NWFETs were applied for quantitative detection of PSA in a buffer and human serum diluted 1/100. Response time was about 5-10s, and analysis time per sample was 1min. The limit of PSA detection was of 23fg/mL, concentration range of 23fg/mL-500ng/mL (7 orders of magnitude). The PSA concentrations determined by the NW FETs in serum were compared with well-established ELISA method. The results matched well with the correlation coefficient of 0.97.

  3. Sensitive determination of glucose in Dulbecco's modified Eagle medium by high-performance liquid chromatography with 1-phenyl-3-methyl-5-pyrazolone derivatization: application to gluconeogenesis studies.

    Science.gov (United States)

    Ling, Zhaoli; Xu, Ping; Zhong, Zeyu; Wang, Fan; Shu, Nan; Zhang, Ji; Tang, Xiange; Liu, Li; Liu, Xiaodong

    2016-04-01

    A new pre-column derivative high-performance liquid chromatography (HPLC) method for determination of d-glucose with 3-O-methyl-d-glucose (3-OMG) as the internal standard was developed and validated in order to study the gluconeogenesis in HepG2 cells. Samples were derivatized with 1-phenyl-3-methy-5-pyrazolone at 70°C for 50 min. Glucose and 3-OMG were extracted by liquid-liquid extraction and separated on a YMC-Triart C18 column, with a gradient mobile phase composed of acetonitrile and 20 mm ammonium acetate solution containing 0.09% tri-ethylamine at a flow rate of 1.0 mL/min. The eluate were detected using a UV detector at 250 nm. The assay was linear over the range 0.39-25 μm (R(2) = 0.9997, n = 5) and the lower limit of quantitation was 0.39 μm (0.070 mg/mL). Intra- and inter-day precision and accuracy were <15% and within ±3%, respectively. After validation, the HPLC method was applied to investigate the gluconeogenesis in Dulbecco's modified Eagle medium (DMEM) cultured HepG2 cells. Glucose concentration was determined to be about 1-2.5 μm in this gluconeogenesis assay. In conclusion, this method has been shown to determine small amounts of glucose in DMEM successfully, with lower limit of quantitation and better sensitivity when compared with common commercial glucose assay kits.

  4. Development of a High-Sensitivity Lab-On-Chip Sensor for In Situ Determinations of Phosphate in Coastal and Open-Ocean Environments

    Science.gov (United States)

    Grand, M. M.; Turner, G. S. C.; Mowlem, M. C.; Achterberg, E. P.; Beaton, A.; Owsianka, D. R.; Slavik, G. J.; Nightingale, A.; Connelly, D.

    2016-02-01

    The development of field-deployable nutrient sensors with a dynamic quantification range suitable for high-frequency sampling in estuaries, coastal waters and oligotrophic seas is essential to improve our understanding of the fluxes and biogeochemical implications of nutrient distributions in the marine environment. By virtue of their compactness, low reagent (power (1.5 W) consumption, microfluidic wet-chemical analysers based on Lab-On-Chip technology provide an attractive means to address this challenge while opening the possibility of in situ monitoring onboard autonomous seagoing platforms such as oceanic gliders. Here we report the development and complete characterization of a stand-alone, microfluidic Lab-On-Chip sensor for phosphate determinations using the classic Molybdenum Blue (MB) method. The sensor is the second iteration of a Lab-On-Chip sensor designed at the National Oceanographic Centre, which was successfully deployed in shallow water environments and gliders for nitrate determinations. The phosphate chemical assay consists of merging streams of an acidic molybdate solution, sample and reducing agent into a 41 mm absorption cell fitted with a LED and photodiode for absorbance quantification. The assay is performed in stopped flow mode, which allows monitoring the kinetics of the reaction as well as altering the dynamic quantification range by varying the length of the stopped flow period. A complete optimization of the assay parameters of the MB method to achieve optimal performance on a microfluidic chip will be described along with results of a deployment in a temperature controlled chamber to address the effect of ambient temperature on the sensitivity of the assay. Data with regards to the long-term stability of the reagents will be presented along with a trial deployment in a shallow water environment. The use of long-path absorbance cells for nanomolar phosphate determinations will also be discussed.

  5. SYBR Green real-time PCR-RFLP assay targeting the plasmodium cytochrome B gene--a highly sensitive molecular tool for malaria parasite detection and species determination.

    Science.gov (United States)

    Xu, Weiping; Morris, Ulrika; Aydin-Schmidt, Berit; Msellem, Mwinyi I; Shakely, Delér; Petzold, Max; Björkman, Anders; Mårtensson, Andreas

    2015-01-01

    A prerequisite for reliable detection of low-density Plasmodium infections in malaria pre-elimination settings is the availability of ultra-sensitive and high-throughput molecular tools. We developed a SYBR Green real-time PCR restriction fragment length polymorphism assay (cytb-qPCR) targeting the cytochrome b gene of the four major human Plasmodium species (P. falciparum, P. vivax, P. malariae, and P. ovale) for parasite detection and species determination with DNA extracted from dried blood spots collected on filter paper. The performance of cytb-qPCR was first compared against four reference PCR methods using serially diluted Plasmodium samples. The detection limit of the cytb-qPCR was 1 parasite/μl (p/μl) for P. falciparum and P. ovale, and 2 p/μl for P. vivax and P. malariae, while the reference PCRs had detection limits of 0.5-10 p/μl. The ability of the PCR methods to detect low-density Plasmodium infections was then assessed using 2977 filter paper samples collected during a cross-sectional survey in Zanzibar, a malaria pre-elimination setting in sub-Saharan Africa. Field samples were defined as 'final positive' if positive in at least two of the five PCR methods. Cytb-qPCR preformed equal to or better than the reference PCRs with a sensitivity of 100% (65/65; 95%CI 94.5-100%) and a specificity of 99.9% (2910/2912; 95%CI 99.7-100%) when compared against 'final positive' samples. The results indicate that the cytb-qPCR may represent an opportunity for improved molecular surveillance of low-density Plasmodium infections in malaria pre-elimination settings.

  6. SYBR Green Real-Time PCR-RFLP Assay Targeting the Plasmodium Cytochrome B Gene – A Highly Sensitive Molecular Tool for Malaria Parasite Detection and Species Determination

    Science.gov (United States)

    Xu, Weiping; Morris, Ulrika; Aydin-Schmidt, Berit; Msellem, Mwinyi I.; Shakely, Delér; Petzold, Max; Björkman, Anders; Mårtensson, Andreas

    2015-01-01

    A prerequisite for reliable detection of low-density Plasmodium infections in malaria pre-elimination settings is the availability of ultra-sensitive and high-throughput molecular tools. We developed a SYBR Green real-time PCR restriction fragment length polymorphism assay (cytb-qPCR) targeting the cytochrome b gene of the four major human Plasmodium species (P. falciparum, P. vivax, P. malariae, and P. ovale) for parasite detection and species determination with DNA extracted from dried blood spots collected on filter paper. The performance of cytb-qPCR was first compared against four reference PCR methods using serially diluted Plasmodium samples. The detection limit of the cytb-qPCR was 1 parasite/μl (p/μl) for P. falciparum and P. ovale, and 2 p/μl for P. vivax and P. malariae, while the reference PCRs had detection limits of 0.5–10 p/μl. The ability of the PCR methods to detect low-density Plasmodium infections was then assessed using 2977 filter paper samples collected during a cross-sectional survey in Zanzibar, a malaria pre-elimination setting in sub-Saharan Africa. Field samples were defined as ‘final positive’ if positive in at least two of the five PCR methods. Cytb-qPCR preformed equal to or better than the reference PCRs with a sensitivity of 100% (65/65; 95%CI 94.5–100%) and a specificity of 99.9% (2910/2912; 95%CI 99.7–100%) when compared against ‘final positive’ samples. The results indicate that the cytb-qPCR may represent an opportunity for improved molecular surveillance of low-density Plasmodium infections in malaria pre-elimination settings. PMID:25774805

  7. A novel dual-function molecularly imprinted polymer on CdTe/ZnS quantum dots for highly selective and sensitive determination of ractopamine

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huilin; Liu, Dongrui; Fang, Guozhen; Liu, Fangfang; Liu, Cuicui; Yang, Yukun [Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457 (China); Wang, Shuo, E-mail: s.wang@tust.edu.cn [Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457 (China)

    2013-01-31

    Highlights: ► We have developed a novel dual-function MIP-coated QDs material. ► The MIP-coated QDs combine the advantage of molecular imprinting and QDs. ► We used MIP-coated QDs as fluorescence sensing material for recognize RAC. ► We used QDs@MIP as sorbent to combine SPE with HPLC for the determination. -- Abstract: A novel dual-function material was synthesized by anchoring a molecularly imprinted polymer (MIP) layer on CdTe/ZnS quantum dots (QDs) using a sol–gel with surface imprinting. The material exhibited highly selective and sensitive determination of ractopamine (RAC) through spectrofluorometry and solid-phase extraction (SPE) coupled with high performance liquid chromatography (HPLC). A series of adsorption experiments revealed that the material showed high selectivity, good adsorption capacity and a fast mass transfer rate. Fluorescence from the MIP-coated QDs was more strongly quenched by RAC than that of the non-imprinted polymer, which indicated that the MIP-coated QDs acted as a fluorescence sensing material could recognize RAC. In addition, the MIP-coated QDs as a sorbent was also shown to be promising for SPE coupled with HPLC for the determination of trace RAC in feeding stuffs and pork samples. Under optimal conditions, the spectrofluorometry and SPE-HPLC methods using the MIP-coated QDs had linear ranges of 5.00 × 10{sup −10}–3.55 × 10{sup −7} and 1.50 × 10{sup −10}–8.90 × 10{sup −8} mol L{sup −1}, respectively, with limits of detection of 1.47 × 10{sup −10} and 8.30 × 10{sup −11} mol L{sup −1}, the relative standard deviations for six repeat experiments of RAC (2.90 × 10{sup −9} mol L{sup −1}) were below 2.83% and 7.11%.

  8. A highly selective and sensitive fluorescence assay for determination of copper(II) and cobalt(II) ions in environmental water and toner samples.

    Science.gov (United States)

    Tsai, Chia-Yi; Lin, Yang-Wei

    2013-02-21

    In this study, a highly selective and sensitive fluorescence assay has been proposed for the determination of copper(II) and cobalt(II) ions in environmental water and toner samples. In the presence of hydrogen peroxide, copper(II) reacted with a new fluorescence reagent Amplex® UltraRed (AUR), forming a fluorescence product only at pH 7.0, while the fluorescence product of cobalt(II) with AUR formed only at pH 9.0. The fluorescence signal obtained was linear with respect to the copper(II) concentration over the range of 1.6-12.0 μM (R(2) = 0.988) and was linear with respect to the cobalt(II) concentration over the range of 45.0 nM to 1.0 μM (R(2) = 0.992). The limits of detection (at a signal-to-noise ratio of 3) for copper(II) and cobalt(II) were 0.17 μM and 14.0 nM, respectively. Our present approach is simpler, faster, and more cost-effective than other techniques for the detection of copper(II) and cobalt(II) ions in environmental water samples and that of copper(II) ions in toner samples.

  9. Direct and sensitive determination of glyphosate and aminomethylphosphonic acid in environmental water samples by high performance liquid chromatography coupled to electrospray tandem mass spectrometry.

    Science.gov (United States)

    Guo, Hongyue; Riter, Leah S; Wujcik, Chad E; Armstrong, Daniel W

    2016-04-22

    A novel method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was developed for the sensitive determination of glyphosate and its major degradation product, AMPA in environmental water samples. The method involves the use of MS compatible mobile phases (0.1% formic acid in water and acetonitrile) for HPLC and direct analysis of water samples without sample derivatization. The method has been validated in different types of water matrices (drinking, surface and groundwater) by accuracy and precision studies with samples spiked at 0.1, 7.5 and 90 ppb. All mean accuracy values ranged from 85% to 112% for glyphosate and AMPA using both primary and secondary quantitative ion transitions (RSD ≤ 10%). Moreover, both primary and secondary ion transitions for glyphosate and AMPA can achieve the quantitation limits at 0.1 ppb. The linear dynamic range of the calibration curves were from 0.1 to 100 ppb for each analyte at each ion transitions with correlation coefficient higher than 0.997.

  10. Simultaneous determination of soy isoflavone glycosides, daidzin and genistin by monoclonal antibody-based highly sensitive indirect competitive enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Sakamoto, Seiichi; Yusakul, Gorawit; Pongkitwitoon, Benyakan; Paudel, Madan Kumar; Tanaka, Hiroyuki; Morimoto, Satoshi

    2015-02-15

    Soy isoflavones are known as major bioactive compounds in soybean (Glycine max), which is an indispensable food. Despite their utility, the consumption of isoflavones has recently been limited because they exhibit oestrogenic and topoisomerase II inhibitory effects. To assess their intake limitation, accurate, sensitive, and effective quantitative analyses are necessary. In this study, we produced the monoclonal antibody (MAb) against daidzin (DZ) and applied it to an indirect competitive enzyme-linked immunosorbent assay (icELISA) for the simultaneous determination of DZ and genistin (GEN), which are known as two major soy isoflavone glycosides in soy products. Using the DZ-MAb, we developed a sensitive icELISA method, where the limit of detection for DZ and GEN was 1.95ng/ml. Several validation analyses revealed that the icELISA is sufficiently accurate and sensitive to be used to assess the overconsumption of soy isoflavones, which would lead to the safe dietary intake of soy products.

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

    NARCIS (Netherlands)

    Gümüscü, B.; Erdogan, Zeynep; Guler, Mustafa O.; Tekinay, Turgay

    2016-01-01

    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 bee

  12. Determining the sensitivity of the high mountain region in Northern Romania to climate and land use changes through multi-proxy analysis

    Science.gov (United States)

    Feurdean, Angelica; Geanta, Anca; Tantau, Ioan; Auer, Andreea; Hutchinson, Simon

    2013-04-01

    Climate and land use changes can have a great impact on high altitude environments due to their species' narrow tolerance capabilities, habitat fragmentation and habitat restriction. Since trees at the timberline and the treeline ecotone grow at their temperature and soil tolerance limit, even small alterations in these parameters can result in marked changes in the position of the treeline ecotone, diversity, and species composition. Current and future climate warming is anticipated to shift the tree and timberlines upwards, whereas land use changes can drive this movement in the opposite direction. Therefore the long-term responses of vegetation to past climate variations and land use changes are of particular relevance for the prediction of future vegetation change in high mountain areas. Here, we use a multi-proxy analysis (pollen, spores, micro and macrocharcoal, mineral magnetic properties and AMS 14C dating) of a 1m lacustrine sequence covering the last 5000 years located in the subalpine zone (1910 m a.s.l.) in the Rodna Mountains (Northern Romanian Carpathians) to determine the sensitivity of high mountain habitats (i.e., movements of the timberline and treeline ecotones, and changes in vegetation composition diversity) in response to climate, fires and land use. The pollen and stomata records reveal regional forests dominated by Pinus sylvestris between ca. 5000 and 4250 cal yrs BP, which were replaced by Picea abies, Abies alba and Fagus sylvatica from about 4200 cal yrs BP onwards. The proximity of the lake was treeless, dominated by sub-alpine shrubs (Alnus viridis), alpine herbaceous communities (Poaceae, Cyperaceae, Apiaceae, Asteraceae Tubuliflorae, A. Liguliflorae, Thalictrum) and ruderal species (Artemisia, Rumex, Chenopodiaceae) through almost the whole record. However, Pinus stomata found between 5000 and 4000 cal yr BP probably indicate a higher position of the treeline and the local occurrence of Pinus before 4000 cal yr BP. Our results show

  13. Development and validation of a simple and sensitive high performance liquid chromatographic method for the simultaneous determination of anastrozole, bicalutamide, tamoxifen, and their synthetic impurities.

    Science.gov (United States)

    Gomes, Fabio Pereira; Garcia, Pedro Lopez

    2012-11-15

    A simple and sensitive analytical method for simultaneous determination of anastrozole, bicalutamide, and tamoxifen as well as their synthetic impurities, anastrozole pentamethyl, bicalutamide 3-fluoro-isomer, and tamoxifen e-isomer, was developed and validated by using high performance liquid chromatography (HPLC). The separation was achieved on a Symmetry(®) C-8 column (100×4.6 mm i.d., 3.5 μm) at room temperature (±24 °C), with a mobile phase consisting of acetonitrile/water containing 0.18% N,N dimethyloctylamine and pH adjusted to 3.0 with orthophosphoric acid (46.5/53.5, v/v) at a flow rate of 1.0 mL min(-1) within 20 min. The detection was made at a wavelength of 270 nm by using ultraviolet (UV) detector. No interference peaks from excipients and relative retention time indicated the specificity of the method. The calibration curve showed correlation coefficients (r) >0.99 calculated by linear regression and analysis of variance (ANOVA). The limit of detection (LOD) and limit of quantitation (LOQ), respectively, were 2.2 and 6.7 μg mL(-1) for anastrozole, 2.61 and 8.72 μg mL(-1) for bicalutamide, 2.0 and 6.7 μg mL(-1) for tamoxifen, 0.06 and 0.22 μg mL(-1) for anastrozole pentamethyl, 0.02 and 0.07 μg mL(-1) for bicalutamide 3-fluoro-isomer, and 0.002 and 0.007 μg mL(-1) for tamoxifen e-isomer. Intraday and interday relative standard deviations (RSDs) were <2.0% (drugs) and <10% (degradation products) as well as the comparison between two different analysts, which were calculated by f test.

  14. Preconcentration sensitive determination of pyrethroid insecticides in environmental water samples with solid phase extraction with SiO2 microspheres cartridge prior to high performance liquid chromatography.

    Science.gov (United States)

    Zhou, Qingxiang; Gao, Yuanyuan; Bai, Huahua; Xie, Guohong

    2010-07-30

    Present study developed a new method for the sensitive determination of pyrethroid insecticides with solid phase extraction in combination with high performance liquid chromatography and UV detector. SiO(2) microspheres, a new SiO(2) based material, was investigated for the enrichment ability and applicability as the solid phase extraction sorbent. Four pyrethroid pesticides such as fenpropathrin, cyhalothrin, fenvalevate and biphenthrin were used as the target analytes. Parameters that maybe influence the extraction efficiency such as the eluent type and its volume, sample flow rate, sample pH, and the sample volume were optimized in detail, and the optimal conditions were as followed: sample volume, 100mL; concentration of methanol, 30%; acetone volume, 5mL; sample flow rate, 4.2mLmin(-1); sample pH, 7. The experimental results indicated that there was good linearity in the concentration range of 0.1-50microgL(-1) except biphenthrin in the range of 0.05-25microgL(-1). The detection limits for fenpropathrin, cyhalothrin, fenvalevate and biphenthrin were in the range of 0.02-0.08microgL(-1). The intra-day and day to day precisions (RSDs, n=6) were in the ranges of 2.6-4.4% and 5.3-7.2%, respectively. The method was validated with five real environmental water samples, and all these results proved that proposed method could be used as a good alternative for the routine analysis for such pollutants in environmental samples.

  15. Sensitive determination method for mercury ion, methyl-, ethyl-, and phenyl-mercury in water and biological samples using high-performance liquid chromatography with chemiluminescence detection.

    Science.gov (United States)

    Kodamatani, Hitoshi; Matsuyama, Akito; Saito, Keiitsu; Kono, Yuriko; Kanzaki, Ryo; Tomiyasu, Takashi

    2012-01-01

    A sensitive determination method for mercury speciation analysis was developed. Four mercury species, mercury ion, methylmercury, ethylmercury, and phenylmercury, were complexed with emetine-dithiocarbamate (emetine-CS(2)), and then injected onto a HPLC instrument coupled with a tris(2,2'-bipyridine)ruthenium(III) chemiluminescence detection system. The emetine-CS(2) complexing agent was effectively used to measure the concentration in addition to serving as a separation and detection reagent. The calibration curves for these mercury complexes were linear in the range of 0.050 - 10 μg L(-1) (as Hg). The limit of detection for (emetine-CS(2))(2)Hg, emetine-CS(2)-methylmercury, emetine-CS(2)-ethylmercury, and emetine-CS(2)-phenylmercury were 30, 17, 21, and 22 ng L(-1), respectively. The sensitivity of this method enables the determination of mercury species in water samples at sub-ppb levels. Furthermore, the method was applied to biological samples in combination with acid leaching and liquid-liquid extraction using emetine-CS(2) as an extraction reagent. The determination results were in good agreement with the values of the certified reference materials.

  16. Development of highly sensitive extractive spectrophotometric determination of nickel(II) in medicinal leaves, soil, industrial effluents and standard alloy samples using pyridoxal-4-phenyl-3-thiosemicarbazone.

    Science.gov (United States)

    Sarma, Loka Subramanyam; Kumar, Jyothi Rajesh; Reddy, Koduru Janardhan; Thriveni, Thenepalli; Reddy, Ammireddy Varada

    2008-01-01

    Pyridoxal-4-phenyl-3-thiosemicarbazone (PPT) is proposed as a new sensitive reagent for the extractive spectrophotometric determination of nickel(II). PPT reacts with nickel(II) in the pH range 4.0-6.0 to form a reddish brown colored complex, which was well-extracted into n-butanol. The absorbance value of the Ni(II)-PPT complex was measured at different time intervals at 430nm, to ascertain the stability of the complex. The system obeyed Beer's law up to 0.5-5.0microgmL(-1) of nickel(II), with an excellent linearity in terms of the correlation coefficient value of 0.99. The molar absorptivity and Sandell's sensitivity of the extracted species are 1.92 x 10(4)Lmol(-1)cm(-1) and 0.003057microgcm(-2) respectively at 430nm. The detection limit of the method is 0.069microgmL(-1). To assess precision and accuracy of the developed method, determinations were carried out at different concentrations. The relative standard deviation of all measurements does not exceed 2.62%. The developed method has been satisfactorily applied for the determination of nickel(II), when present alone or in the presence of diverse ions, which are usually associated with nickel(II) in medicinal leaves, soil and industrial effluent samples. Various standard and certified reference materials (CM 247 LC, IN 718, BCS 233, 266, 253 and 251) have also been tested for the determination of nickel for the purpose of validation of the present method. The results of the proposed method are compared with those obtained from an atomic absorption spectrometer (AAS).

  17. High sensitivity RNA pseudoknot prediction

    OpenAIRE

    Huang, Xiaolu; Ali, Hesham

    2006-01-01

    Most ab initio pseudoknot predicting methods provide very few folding scenarios for a given RNA sequence and have low sensitivities. RNA researchers, in many cases, would rather sacrifice the specificity for a much higher sensitivity for pseudoknot detection. In this study, we introduce the Pseudoknot Local Motif Model and Dynamic Partner Sequence Stacking (PLMM_DPSS) algorithm which predicts all PLM model pseudoknots within an RNA sequence in a neighboring-region-interference-free fashion. T...

  18. High blood pressure and visual sensitivity

    Science.gov (United States)

    Eisner, Alvin; Samples, John R.

    2003-09-01

    The study had two main purposes: (1) to determine whether the foveal visual sensitivities of people treated for high blood pressure (vascular hypertension) differ from the sensitivities of people who have not been diagnosed with high blood pressure and (2) to understand how visual adaptation is related to standard measures of systemic cardiovascular function. Two groups of middle-aged subjects-hypertensive and normotensive-were examined with a series of test/background stimulus combinations. All subjects met rigorous inclusion criteria for excellent ocular health. Although the visual sensitivities of the two subject groups overlapped extensively, the age-related rate of sensitivity loss was, for some measures, greater for the hypertensive subjects, possibly because of adaptation differences between the two groups. Overall, the degree of steady-state sensitivity loss resulting from an increase of background illuminance (for 580-nm backgrounds) was slightly less for the hypertensive subjects. Among normotensive subjects, the ability of a bright (3.8-log-td), long-wavelength (640-nm) adapting background to selectively suppress the flicker response of long-wavelength-sensitive (LWS) cones was related inversely to the ratio of mean arterial blood pressure to heart rate. The degree of selective suppression was also related to heart rate alone, and there was evidence that short-term changes of cardiovascular response were important. The results suggest that (1) vascular hypertension, or possibly its treatment, subtly affects visual function even in the absence of eye disease and (2) changes in blood flow affect retinal light-adaptation processes involved in the selective suppression of the flicker response from LWS cones caused by bright, long-wavelength backgrounds.

  19. Development of a highly sensitive extractive spectrophotometric method for the determination of nickel(II) from environmental matrices using N-ethyl-3-carbazolecarboxaldehyde-3-thiosemicarbazone.

    Science.gov (United States)

    Ramachandraiah, C; Rajesh Kumar, J; Janardhan Reddy, K; Lakshmi Narayana, S; Varada Reddy, A

    2008-09-01

    Nickel(II) reacts with N-ethyl-3-carbazolecarboxaldehyde-3-thiosemicarbazone (ECCT) and forms a yellow colored complex, which was extracted into n-butanol from sodium acetate and acetic acid buffer at pH 6.0. The absorbance value of the Ni(II)-ECCT complex was measured at different intervals of time at 400 nm, to ascertain the time stability of the complex. The extraction of the complex into the solvent was instantaneous and stable for more than 72 h. The system obeyed Beer's law in the concentration range of 1.2-5.6 microg ml(-1) of nickel(II), with an excellent linearity and a correlation coefficient of 0.999. The molar absorptivity and Sandell's sensitivity of the extracted species were found to be 1.114 x 10(4)L mol(-1)cm(-1) and 5.29 x 10(-3)microg cm(-2) at 400 nm, respectively. Hence, a detailed study of the extraction of nickel(II) with ECCT has been undertaken with a view to developing a rapid and sensitive extractive spectrophotometric method for the determination of nickel(II) when present alone or in the presence of diverse ions which are usually associated with nickel(II) in environmental matrices like soil and industrial effluents. Various standard alloy samples (CM 247 LC, IN 718, BCS 233, 266, 253 and 251) have been tested for the determination of nickel for the purpose of validation of the present method. The results of the proposed method are comparable with those from atomic absorption spectrometry and were found to be in good agreement.

  20. Microwave assisted saponification (MAS) followed by on-line liquid chromatography (LC)-gas chromatography (GC) for high-throughput and high-sensitivity determination of mineral oil in different cereal-based foodstuffs.

    Science.gov (United States)

    Moret, Sabrina; Scolaro, Marianna; Barp, Laura; Purcaro, Giorgia; Conte, Lanfranco S

    2016-04-01

    A high throughput, high-sensitivity procedure, involving simultaneous microwave-assisted extraction (MAS) and unsaponifiable extraction, followed by on-line liquid chromatography (LC)-gas chromatography (GC), has been optimised for rapid and efficient extraction and analytical determination of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in cereal-based products of different composition. MAS has the advantage of eliminating fat before LC-GC analysis, allowing an increase in the amount of sample extract injected, and hence in sensitivity. The proposed method gave practically quantitative recoveries and good repeatability. Among the different cereal-based products analysed (dry semolina and egg pasta, bread, biscuits, and cakes), egg pasta packed in direct contact with recycled paperboard had on average the highest total MOSH level (15.9 mg kg(-1)), followed by cakes (10.4 mg kg(-1)) and bread (7.5 mg kg(-1)). About 50% of the pasta and bread samples and 20% of the biscuits and cake samples had detectable MOAH amounts. The highest concentrations were found in an egg pasta in direct contact with recycled paperboard (3.6 mg kg(-1)) and in a milk bread (3.6 mg kg(-1)).

  1. 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.

    Science.gov (United States)

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

    2017-08-26

    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.

  2. Synthesis of palladium nanoparticles on organically modified silica: application to design of a solid-state electrochemiluminescence sensor for highly sensitive determination of imipramine.

    Science.gov (United States)

    Safavi, Afsaneh; Banazadeh, Alireza; Sedaghati, Fatemeh

    2013-09-24

    Organically modified silica substrate containing amine and vinyl functional groups were used for reduction and stabilization of palladium nanoparticles. Uniform spherical nanoparticles of palladium with average diameter of 10 nm were formed on silica substrate by direct contact of the substrate with an aqueous solution of palladium precursor, without the addition of any chemical reducer. Moreover, a sensitive and selective solid state electrochemiluminescence sensor was fabricated for the determination of imipramine, based on Ru(bpy)3(2+)-palladium nanoparticles doped carbon ionic liquid electrode. In this process, imipramine acts as a co-reactant for Ru(bpy)3(2+). It is believed that the enhancement of the electrochemiluminescence signal in the presence of palladium nanoparticles in the composite is due to palladium catalytic effect on electrochemical and also chemical process involved in formation of Ru(byp)3(2+)*. In addition, the results confirmed that, the rigid composite electrode shows the characteristic of microelectrode arrays. The proposed method was applied to the determination of imipramine in tablets and urine samples. The electrochemiluminescence intensity showed good linearity with the imipramine concentration from 1-100 pM, with a detection limit of 0.1 pM.

  3. Highly sensitive method for simultaneous determination of nine alkaloids of Shuanghua Baihe tablets in human plasma by LC-MS/MS and its application.

    Science.gov (United States)

    Wu, Yao; Liu, Ruijuan; Gu, Pan; Cheng, Minlu; Zheng, Lu; Liu, Yujie; Ma, Pengcheng; Ding, Li

    2015-12-15

    Shuanghua Baihe tablets (SBT) is a traditional Chinese medicinal formula which has been used to treat recurrent aphthous stomatitis for many years. To study the pharmacokinetic profiles of berberine, epiberberine, coptisine, palmatine, jatrorrhizine, magnoflorine, berberrubine, corynoline and acetylcorynoline in human after administration of SBT, a sensitive liquid chromatography-tandem mass spectrometry method was developed and fully validated for the simultaneous quantification of these nine alkaloids in human plasma. After protein precipitation, the nine alkaloids in human plasma sample was separated on a Hanbon C18 (150mm×2.1mm, 5μm) column with gradient elution using methanol and 0.5% formic acid water solution, and detected by a triple quadrupole mass spectrometer with an electrospray ionization source. It is a challenge to design different calibration ranges for different analytes in a bioanalytical method for simultaneous determination of multi-analytes in bio-samples. To ensure that each alkaloid in the plasma was determined accurately by the simultaneous quantitation method, the upper limits of quantification for the nine alkaloids were designed at 100, 300, 800, 1800 and 5000pg/mL, respectively, according to the maximum plasma concentration value of each alkaloid obtained from the pilot pharmacokinetic study. The lower limit of quantification was 15pg/mL for berberine, epiberberine, coptisine, magnoflorine, berberrubine, corynoline and acetylcorynoline, while for palmatine and jatrorrhizine it was 1.5pg/mL. This method was successfully applied to investigate the pharmacokinetic profiles of the nine alkaloids in healthy Chinese volunteers after a single oral administration of SBT.

  4. Rapid and sensitive determination of benzo[a]pyrene in black ginseng using fluorescence detector and high performance liquid chromatography-tandem mass spectrometry

    Science.gov (United States)

    Cho, Hyun-jeong; Kim, Hye-jin; Son, Byeong-cheol; Jo, Dong-keun; Cho, Byung-lim

    2013-05-01

    Black ginseng is produced by steaming a ginseng root followed by drying repeatedly 9 times during the process and it is changed to be black color, so it is known that a black ginseng has more contents of saponins than red ginseng. However a fake black ginseng which is produced to be black color at high temperature in a short period of time generate carcinogenic benzo[a]pyrene(BaP) through the process. In this year, maximum residue level(MRL) for BaP was established to 2 ug/kg in black ginseng and more sensitive method was developed to quantitatively analyze the BaP by high performance liquid chromatography (HPLC) coupling with florescence detector and tandem mass spectrometry (atmospheric pressure chemical ionization-MS/MS). Chromatographic separation was performed on a Supelcosil™ LC-PAH column (3 μm, 3 mm x 50 mm). Mobile phase A was water and mobile phase B was acetonitrile. BaP was exactly separated from other 15 polycyclic aromatic hydrocarbons (PAHs) which have been selected as priority pollutants by the US Environmental Protection Agency (EPA). Linearity of detection was in the range of 0.2~20 μg/kg and limit of detection (LOD) for BaP was lower than 0.1 μg/kg, limit of quantification (LOQ) was 0.2 μg/kg. The recovery of Bap was 92.54%+/-6.3% in black ginseng.

  5. Using a new high resolution regional model for malaria that accounts for population density and surface hydrology to determine sensitivity of malaria risk to climate drivers

    Science.gov (United States)

    Tompkins, Adrian; Ermert, Volker; Di Giuseppe, Francesca

    2013-04-01

    In order to better address the role of population dynamics and surface hydrology in the assessment of malaria risk, a new dynamical disease model been developed at ICTP, known as VECTRI: VECtor borne disease community model of ICTP, TRIeste (VECTRI). The model accounts for the temperature impact on the larvae, parasite and adult vector populations. Local host population density affects the transmission intensity, and the model thus reproduces the differences between peri-urban and rural transmission noted in Africa. A new simple pond model framework represents surface hydrology. The model can be used on with spatial resolutions finer than 10km to resolve individual health districts and thus can be used as a planning tool. Results of the models representation of interannual variability and longer term projections of malaria transmission will be shown for Africa. These will show that the model represents the seasonality and spatial variations of malaria transmission well matching a wide range of survey data of parasite rate and entomological inoculation rate (EIR) from across West and East Africa taken in the period prior to large-scale interventions. The model is used to determine the sensitivity of malaria risk to climate variations, both in rainfall and temperature, and then its use in a prototype forecasting system coupled with ECMWF forecasts will be demonstrated.

  6. Highly sensitive determination of Schisandrin and Schisandrin B in plasma of rats after administration of Wurenchun (Fructus Schisandrae Chinensis Extracts) preparations by LC-ESI-MS/MS.

    Science.gov (United States)

    Tang, Jingling; Shao, Bing; Liu, Yan; Liu, Hongmei; Ji, Hongyu; Zhu, Daling; Wu, Linhua

    2010-06-01

    A sensitive and specific method based on liquid chromatography-tandem mass spectrometry using electrospray ionization (LC-ESI-MS/MS) has been developed for the determination of Schisandrin and Schisandrin B in rat plasma. A 100 microL plasma sample was extracted by methyl tert-butyl ether after spiking the samples with nimodipine (internal standard) and performed on an XTerra(R)MS-C(18) column (150 mm x 2.1 mm, 3.5 mum) with the mobile phase of acetonitrile-water-formic acid (80:20:0.2, v/v) at a flow rate of 0.2 mL/min in a run time of 8.5 min. The lower limit of quantification of the method was 40 ng/mL for Schisandrin and 20 ng/mL for Schisandrin B. The method showed reproducibility with intra-day and inter-day precision of less than 13.8% RSD, as well as accuracy, with inter- and intra-assay accuracies between 93.5 and 107.2%. Finally, the LC-ESI-MS/MS method was successfully applied to study the pharmacokinetics of Schisandrin and Schisandrin B in rats after administration of Wurenchun commercial formulations to rats.

  7. High sensitivity radon emanation measurements.

    Science.gov (United States)

    Zuzel, G; Simgen, H

    2009-05-01

    The presented radon detection technique employs miniaturized ultra-low background proportional counters. (222)Rn samples are purified, mixed with a counting gas and filled into a counter using a special glass vacuum line. The absolute sensitivity of the system is estimated to be 40 microBq (20 (222)Rn atoms). For emanation investigations two metal sealed stainless steel vessels and several glass vials are available. Taking into account their blank contributions, measurements at a minimum detectable activity of about 100 microBq can be performed.

  8. Determination of soil organic phosphorus exchange sensitivity

    Science.gov (United States)

    Shand, Charles; Wendler, Renate; Lumsdon, David; Cooper, Pat; George, Timothy; Brown, Lawrie; Giles, Courtney; Stutter, Marc; Menezes-Blackburn, Daniel; Zhang, Hao; Wearing, Catherine; Haygarth, Philip; Blackwell, Martin; Darch, Tegan

    2015-04-01

    Soils contain both organic and inorganic phosphorus (P) species in varying proportions. Studies have shown that many soils contain substantial amounts of inositol hexaphosphate (IHP) and there is much interest worldwide in developing strategies to make some use of this recalcitrant resource for plant growth to reduce P fertilizer inputs. Little is known about the preference of ion exchange processes in the solubilisation of organic vs inorganic P forms in soils, an important first step in making P forms bioavailable. Although they do not possess biotic functions, resins provides a simple means to deplete P forms in soil allowing investigation of exchange selectivity between inorganic and organic P forms. The aim of our work was to determine new understanding of exchange selectivity in soils and provide insight into potential depletion and plant uptake of soil phosphorus, with emphasis on organic forms such as IHP. For our study we used a Cambisol sampled from an agricultural area (Tayport) near Dundee in Scotland. The soil had a high Olsen (0.5 M sodium bicarbonate at pH 8.5) extractable P status (84 mg P/kg) and P-31 nuclear magnetic resonance analysis of its NaOH/EDTA extract showed it contained a substantial proportion of IHP (21 % of total extractable P). For resin extraction we used anion exchange resin sheets (4.17 cm each side) in bicarbonate form to minimise pH related solubilisation effects. We used 3.5 g of soil in 75 ml of water and added 1, 2 or 3 resin squares. After equilibration the resin squares were removed and replaced with fresh resin squares a further 3 times. Phosphorus was recovered from the resin sheets by elution with 0.25 M sulphuric acid and analysed by inductively coupled plasma spectroscopy to determine total P, and colorimetrically with malachite green to determine inorganic P with the remainder assigned to organic P. The data showed that the resin preferentially removed inorganic P and even after four sequential extractions little or

  9. Cryogenic High-Sensitivity Magnetometer

    Science.gov (United States)

    Day, Peter; Chui, Talso; Goodstein, David

    2005-01-01

    A proposed magnetometer for use in a cryogenic environment would be sensitive enough to measure a magnetic-flux density as small as a picogauss (10(exp -16) Tesla). In contrast, a typical conventional flux-gate magnetometer cannot measure a magnetic-flux density smaller that about 1 microgauss (10(exp -10) Tesla). One version of this device, for operation near the low end of the cryogenic temperature range, would include a piece of a paramagnetic material on a platform, the temperature of which would be controlled with a periodic variation. The variation in temperature would be measured by use of a conventional germanium resistance thermometer. A superconducting coil would be wound around the paramagnetic material and coupled to a superconducting quantum interference device (SQUID) magnetometer.

  10. A novel platform for high sensitivity determination of PbP2a based on gold nanoparticles composited graphitized mesoporous carbon and doxorubicin loaded hollow gold nanospheres.

    Science.gov (United States)

    Yang, Juan; Shen, Huawei; Zhang, Xing; Tao, Yiyi; Xiang, Hua; Xie, Guoming

    2016-03-15

    Gold nanoparticles composite graphitized mesoporous carbon nanoparticles (GMCs@AuNPs) biocomposite with the signal amplification capability was successfully synthesized for use in an immunoassay for penicillin binding protein 2 a (PbP2a). The polyamidoamine (PAMAM) dendrimers were first electrodeposited onto the Au electrode can greatly increase the amount of the captured antibodies. Protein A was used to properly orientate immobilized antibody against PbP2a, which strongly improved specificity of the antigen-antibody binding. Hollow gold nanospheres (HGNPs) as effective nanocarriers have been synthesized by sacrificial galvanic replacement of cobalt nanoparticles capable of encapsulating doxorubicin (Dox). The obtained HGNPs@Dox bionanocomposite was used for further loading of detection antibody (Ab2) to form the HGNPs@Dox@Ab2 bioconjugate. Then, the differential pulse voltammetric signals related to the concentration of PbP2a for Dox could be detected, and the immunosensor exhibited a detection limit as low as 0.65 pg mL(-1) (at an S/N ratio of 3). The proposed method with an excellent differentiation ability showed high sensitivity and specificity. The morphologies and electrochemistry properties of the composites were investigated by scanning electron microscopy, electrochemical characterization, UV-visible absorption spectroscopy, fluorescence spectrophotometer and Malvern laser particle size analyzer, respectively. In addition, the basic approach described here would be applicable towards developing biodetection assays against other important targets. Moreover, the bioconjugate of HGNPs@Dox is also a promising pattern to delivery Dox in vivo for anticancer therapy.

  11. Dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-diode array detection as an efficient and sensitive technique for determination of antioxidants.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Bahram, Morteza; Jönsson, Jan Ake

    2007-05-15

    Dispersive liquid-liquid microextraction (DLLME) and high performance liquid chromatography-diode array detection (HPLC-DAD) was presented for extraction and determination of Irganox 1010, Irganox 1076 and Irgafos 168 (antioxidants) in aqueous samples. Carbon tetrachloride at microliter volume level and acetonitrile were used as extraction and dispersive solvents, respectively. The main advantages of method are high speed, high enrichment factor, high recovery, good repeatability and extraction solvent volume at microL level. Limit of detection for analytes is between 3 and 7 ng mL(-1). One variable at a time optimization and response surface modeling were used to obtain optimum conditions for microextraction procedure and nearly same experimental conditions were obtained using both optimization methods. Recoveries in the ranges 78-86% and 84-110% were obtained by one variable at a time and response surface modeling, respectively. Using tap water and packed water as matrices do not show any detrimental effect on the extraction recoveries and enrichment factors of analytes.

  12. A novel pre-column fluorescent derivatization method for the sensitive determination of aristolochic acids in medicinal herbs by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Guo, Lin; Yue, Hao; Cai, Zongwei

    2010-09-21

    Aristolochic acids (AAs) are a family of structurally related nitrophenanthrene carboxylic acids existing in Aristolochia, Bragantia, and Asarum species. AAs have been proven to have nephrotoxic and carcinogenic toxicity. In this study, a novel pre-column fluorescence derivatization procedure followed by high-performance liquid chromatography-fluorescence detection (HPLC-FLD) is developed for the analysis of AAs in medicinal herbs. The nitro group in the phenanthrene ring of AAs was removed by NaBH(4) in water-THF (2:1, v/v), resulting in the corresponding aristolic acids. The analysis of AAs in medicinal herbs was based of the sensitive fluorescence detection of aristolic acids after the chemical derivatization. Because the produced aristolic acids are highly fluorescent the limit of detection (LOD) of AAI and AAII were lowered to 0.06 and 0.04 ng/mL, respectively, which is at least an order of magnitude lower than those in the reported HPLC and LC-MS methods. Good linearity with correlation coefficients higher than 0.997 were obtained for AAI and AII in the calibration ranges of 0.2-800 ng/mL. The derivatization conditions such as reaction temperature, time and the amount of NaBH(4) were optimized. The developed method provided satisfactory intra-day and inter-day precisions with RSDs less than 1.4% and 3.8%, respectively. The relative analytical error was less than 7% for the analysis of AAI and AAII in spiked matrix samples.

  13. Nano-textured high sensitivity ion sensitive field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Hajmirzaheydarali, M.; Sadeghipari, M.; Akbari, M.; Shahsafi, A.; Mohajerzadeh, S., E-mail: mohajer@ut.ac.ir [Thin Film and Nanoelectronics Lab, Nanoelectronics Center of Excellence, School of Electrical and Computer Engineering, University of Tehran, Tehran 143957131 (Iran, Islamic Republic of)

    2016-02-07

    Nano-textured gate engineered ion sensitive field effect transistors (ISFETs), suitable for high sensitivity pH sensors, have been realized. Utilizing a mask-less deep reactive ion etching results in ultra-fine poly-Si features on the gate of ISFET devices where spacing of the order of 10 nm and less is achieved. Incorporation of these nano-sized features on the gate is responsible for high sensitivities up to 400 mV/pH in contrast to conventional planar structures. The fabrication process for this transistor is inexpensive, and it is fully compatible with standard complementary metal oxide semiconductor fabrication procedure. A theoretical modeling has also been presented to predict the extension of the diffuse layer into the electrolyte solution for highly featured structures and to correlate this extension with the high sensitivity of the device. The observed ultra-fine features by means of scanning electron microscopy and transmission electron microscopy tools corroborate the theoretical prediction.

  14. Highly sensitive determination of sunset yellow FCF (E110) in food products based on Chitosan/Nanoparticles/MWCNTs with modified gold electrode

    Science.gov (United States)

    Rovina, K.; Siddiquee, S.; Shaarani, S. M.

    2016-06-01

    Sunset Yellow belongs to the family of azo dyes, commonly used in food industry. High consumption of Sunset Yellow can cause health problem to human. Due to arising of the health issues, there are several analytical methods available for determination of Sunset Yellow. However, these methods are required skilled manpower, complicated procedures, time consuming and high cost. Herein, an electrochemical sensor was developed based on the combination of chitosan (CHIT), calcium oxide nanoparticles (CaONPs) and multiwall carbon nanotubes (MWCNTs) sensing film for detection of Sunset Yellow in food products. Electrochemical behavior of the modified gold electrode in the presence of Sunset Yellow was studied by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The morphological characteristics of CHIT/CaONPs/MWCNTs were observed under scanning electron microscope and transmission electron microscope. Under optimal conditions, the DPV was detected with different concentrations of Sunset Yellow in the range of 0.9 to 10 ppm, with detection limit of 0.8 ppm. The developed method has successfully applied for monitoring the presence of Sunset Yellow with different food products including candy, royal jelly, ice cream and soft drink with satisfactory results.

  15. Fe(III)-based metal-organic framework-derived core-shell nanostructure: Sensitive electrochemical platform for high trace determination of heavy metal ions.

    Science.gov (United States)

    Zhang, Zhihong; Ji, Hongfei; Song, Yingpan; Zhang, Shuai; Wang, Minghua; Jia, Changchang; Tian, Jia-Yue; He, Linghao; Zhang, Xiaojing; Liu, Chun-Sen

    2017-03-07

    A new core-shell nanostructured composite composed of Fe(III)-based metal-organic framework (Fe-MOF) and mesoporous Fe3O4@C nanocapsules (denoted as Fe-MOF@mFe3O4@mC) was synthesized and developed as a platform for determining trace heavy metal ions in aqueous solution. Herein, the mFe3O4@mC nanocapsules were prepared by calcining the hollow Fe3O4@C that was obtained using the SiO2 nanoparticles as the template, followed by composing the Fe-MOF. The Fe-MOF@mFe3O4@mC nanocomposite demonstrated excellent electrochemical activity, water stability and high specific surface area, consequently resulting in the strong biobinding with heavy-metal-ion-targeted aptamer strands. Furthermore, by combining the conformational transition interaction, which is caused by the formation of the G-quadruplex between a single-stranded aptamer and high adsorbed amounts of heavy metal ions, the developed aptasensor exhibited a good linear relationship with the logarithm of heavy metal ion (Pb(2+) and As(3+)) concentration over the broad range from 0.01 to 10.0nM. The detection limits were estimated to be 2.27 and 6.73 pM toward detecting Pb(2+) and As(3+), respectively. The proposed aptasensor showed good regenerability, excellent selectivity, and acceptable reproducibility, suggesting promising applications in environment monitoring and biomedical fields.

  16. Rapid and sensitive method for the determination of acetaldehyde in fuel ethanol by high-performance liquid chromatography with UV-Vis detection

    Energy Technology Data Exchange (ETDEWEB)

    Saczk, Adelir Aparecida; Okumura, Leonardo Luiz; Firmino de Oliveira, Marcelo; Boldrin Zanoni, Maria Valnice; Ramos Stradiotto, Nelson [Instituto de Quimica, UNESP, Quitandinha, Araraquara, SP (Brazil)

    2005-04-01

    A high-performance liquid chromatography (HPLC) method for the determination of acetaldehyde in fuel ethanol was developed. Acetaldehyde was derivatized with 0.900 mL 2,4-dinitrophenylhydrazine (DNPHi) reagent and 50 {mu}L phosphoric acid 1 mol L{sup -1} at a controlled room temperature of 15 C for 20 min. The separation of acetaldehyde-DNPH (ADNPH) was carried out on a Shimadzu Shim-pack C{sub 18} column, using methanol/LiCl{sub (aq)} 1.0 mM (80/20, v/v) as a mobile phase under isocratic elution and UV-Vis detection at 365 nm. The standard curve of ADNPH was linear in the range 3-300 mg L{sup -1} per injection (20 {mu}L) and the limit of detection (LOD) for acetaldehyde was 2.03 {mu}g L{sup -1}, with a correlation coefficient greater than 0.999 and a precision (relative standard deviation, RSD) of 5.6% (n=5). Recovery studies were performed by fortifying fuel samples with acetaldehyde at various concentrations and the results were in the range 98.7-102%, with a coefficient of variation (CV) from 0.2% to 7.2%. Several fuel samples collected from various gas stations were analyzed and the method was successfully applied to the analysis of acetaldehyde in fuel ethanol samples. (orig.)

  17. Characterization of a titanium(IV)-porphyrin complex as a highly sensitive and selective reagent for the determination of hydrogen peroxide: a computational chemistry approach and a critical review.

    Science.gov (United States)

    Takamura, Kiyoko; Matsumoto, Takatoshi

    2008-06-01

    The Ti-TPyP reagent, i.e. an acidic aqueous solution of the oxo[5,10,15,20-tetra(4-pyridyl)porphyrinato] titanium(IV) complex, TiO(tpyp), was developed as a highly sensitive and selective spectrophotometric reagent for determination of traces of hydrogen peroxide. Using this reagent, determination of hydrogen peroxide was performed by flow-injection analysis with a detection limit of 0.5 pmol per test. The method was actually applied to determination of several constituents of foods, human blood, and urine mediated by appropriate oxidase enzymes. The reaction specificity of the TiO(tpyp) complex for hydrogen peroxide was clarified from the viewpoint of the reaction mechanisms and molecular orbitals based on ab initio calculations. The results provided a well-grounded argument for determination of hydrogen peroxide using the Ti-TPyP reagent experimentally. This review deals with characterization of the high sensitivity and reaction specificity of the Ti-TPyP reagent for determination of hydrogen peroxide, to prove its reliability in analytical applications.

  18. Physical determinants of radiation sensitivity in bacterial spores

    Energy Technology Data Exchange (ETDEWEB)

    Powers, E.L.

    1982-01-01

    Several factors modifying radiation sensitivity in dry bacterial spores are described and discussed. Vacuum inducing the loss of critical structural water, very low dose rates of radiation from which the cell may recover, radiations of high linear energy transfer, and the action of temperature over long periods of time on previously irradiated cells are recognized from extensive laboratory work as important in determining survival of spores exposed to low radiation doses at low temperatures for long periods of time. Some extensions of laboratory work are proposed.

  19. Use of a modified, high-sensitivity, anodic stripping voltammetry method for determination of zinc speciation in the North Atlantic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Jakuba, Rachel Wisniewski [Massachusetts Institute of Technology, Woods Hole Oceanographic Institution Joint Program in Chemical Oceanography, 266 Woods Hole Road, Woods Hole, MA 02543 (United States)], E-mail: jakuba.rachel@epa.gov; Moffett, James W. [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, MA 02543 (United States)], E-mail: jmoffett@usc.edu; Saito, Mak A. [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, MA 02543 (United States)

    2008-05-05

    Zinc speciation is considered to be an important determinant of the biological availability of zinc. Yet in oceanic surface waters, characterization of zinc speciation is difficult due to the low concentrations of this essential micronutrient. In this study, an anodic stripping voltammetry method previously developed for the total determination of cadmium and lead was successfully adapted to the measurement of zinc speciation. The method differs from previous zinc speciation anodic stripping voltammetry methods in that a fresh mercury film is plated with each sample aliquot. The fresh film anodic stripping voltammetry method was compared to competitive ligand exchange cathodic stripping voltammetry in a profile from the North Atlantic Ocean. Results using the fresh film anodic stripping voltammetry method were similar to those determined using the cathodic stripping voltammetry method, though ligand concentrations determined by fresh film anodic stripping voltammetry were generally slightly higher than those determined by cathodic stripping voltammetry. There did not seem to be a systematic difference between methods for the estimates of conditional stability constants. The ligand concentration in the North Atlantic profile ranged from 0.9 to 1.5 nmol L{sup -1} as determined by fresh film anodic stripping voltammetry and 0.6 to 1.3 nmol L{sup -1} as determined by cathodic stripping voltammetry. The conditional stability constants determined by fresh film anodic stripping voltammetry were 10{sup 9.8}-10{sup 10.5} and by cathodic stripping voltammetry were 10{sup 9.8}-10{sup 11.3}.

  20. Use of a modified, high-sensitivity, anodic stripping voltammetry method for determination of zinc speciation in the North Atlantic Ocean.

    Science.gov (United States)

    Jakuba, Rachel Wisniewski; Moffett, James W; Saito, Mak A

    2008-05-05

    Zinc speciation is considered to be an important determinant of the biological availability of zinc. Yet in oceanic surface waters, characterization of zinc speciation is difficult due to the low concentrations of this essential micronutrient. In this study, an anodic stripping voltammetry method previously developed for the total determination of cadmium and lead was successfully adapted to the measurement of zinc speciation. The method differs from previous zinc speciation anodic stripping voltammetry methods in that a fresh mercury film is plated with each sample aliquot. The fresh film anodic stripping voltammetry method was compared to competitive ligand exchange cathodic stripping voltammetry in a profile from the North Atlantic Ocean. Results using the fresh film anodic stripping voltammetry method were similar to those determined using the cathodic stripping voltammetry method, though ligand concentrations determined by fresh film anodic stripping voltammetry were generally slightly higher than those determined by cathodic stripping voltammetry. There did not seem to be a systematic difference between methods for the estimates of conditional stability constants. The ligand concentration in the North Atlantic profile ranged from 0.9 to 1.5 nmol L(-1) as determined by fresh film anodic stripping voltammetry and 0.6 to 1.3 nmol L(-1) as determined by cathodic stripping voltammetry. The conditional stability constants determined by fresh film anodic stripping voltammetry were 10(9.8)-10(10.5) and by cathodic stripping voltammetry were 10(9.8)-10(11.3).

  1. Highly sensitive and selective determination of pyrazinamide at poly-L-methionine/reduced graphene oxide modified electrode by differential pulse voltammetry in human blood plasma and urine samples.

    Science.gov (United States)

    Cheemalapati, Srikanth; Devadas, Balamurugan; Chen, Shen-Ming

    2014-03-15

    In this current study we used electrochemically active film which contains poly-L-methionine (PMET) and electrochemically reduced graphene oxide (ERGO) on glassy carbon electrode (GCE) for pyrazinamide (PZM) detection. The electrocatalytic response of analyte at PMET/ERGO/GCE film was measured using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In addition, electrochemical impedance studies revealed that the smaller R(ct) value observed at PMET/ERGO film modified GCE which authenticates its good conductivity and faster electron transfer rate. The prepared PMET/ERGO/GCE film exhibits excellent DPV response towards PZM and the reduction peak current increased linearly with respect to PZM concentration in the linear range between 0.4 μM to 1129 μM with a sensitivity of 0.266 μA μM(-1) cm(-2). Real sample studies were carried out in human blood plasma and urine samples, which offered good recovery and revealed the promising practicality of the sensor for PZM detection. The proposed sensor displayed a good selectivity, repeatability, sensitivity with appreciable consistency and good reproducibility. In addition, the proposed electrochemical sensor showed good results towards the commercial pharmaceutical PZM samples.

  2. A simple and sensitive high-performance liquid chromatography method for determination of ciprofloxacin in bioavailability studies of conventional and gastroretentive prolonged-release formulations

    Directory of Open Access Journals (Sweden)

    Jaber Emami

    2016-01-01

    Conclusion: This validated HPLC method was successfully used for the determination of ciprofloxacin in human plasma following oral administration of controlled release formulation, conventional immediate-release tablets and when administered concomitantly with divalent and trivalent cations such as aluminum-, magnesium-, or calcium-containing products under which the bioavailability of ciprofloxacin is significantly reduced.

  3. Headspace solvent microextraction as a simple and highly sensitive sample pretreatment technique for ultra trace determination of geosmin in aquatic media.

    Science.gov (United States)

    Bagheri, Habib; Salemi, Amir

    2006-01-01

    A headspace solvent microextraction method was developed for the trace determination of geosmin, an odorant compound, in water samples. After performing the extraction by a microdrop of an organic solvent, the microdrop was introduced directly into a GC-MS injection port. One-at-the-time optimization strategy was applied to investigate and optimize some important extraction parameters such as type of solvent, drop volume, temperature, stirring rate, ionic strength, sample volume, and extraction time. The analytical data exhibited an RSD of less than 5% (n = 5), a linear calibration range of 5-900 ng/L (r2 > 0.998), and a detection limit of 0.8 and 3.3 ng/L using two different sets of selected ions. The proposed method was successfully applied to the extraction and determination of geosmin in the spiked real water sample and reasonable recovery was achieved.

  4. A highly sensitive and selective bulk optode based on benzimidazol derivative as an ionophore and ETH5294 for the determination of ultra trace amount of silver ions.

    Science.gov (United States)

    Firooz, Ali R; Ensafi, Ali A; Kazemifard, Nafiseh; Sharghi, Hashem

    2012-11-15

    A novel optical chemical sensor (optode) was fabricated for the determination of silver ions. The optical sensor was prepared by incorporating recently synthesized ionophore, 7-(1H-benzimidazol-1-ylmethyl)-5,6,7,8,9,10-hexahydro-2H-1,13,4,7,10-benzodioxatriaza cyclopentadecine-3,11(4H,12H)-dione, sodium tetraphenyl borate (NaTPB) as an anionic additive, 3-octadecanoylimino-7-(diethylamino)-1,2-benzophenoxazine (ETH5294) as a chromoionophore, and dioctyl phthalate (DOP) as a plasticizer in a poly(vinyl chloride) membrane. The effect of several parameters in determining Ag(+) was studied and optimized. The spectrophotometric method (λ(max) of 660 nm) was used for the determination of Ag(+). Under the optimum conditions, the optical sensor has a wide dynamic range of 1.02×10(-11) to 8.94×10(-5) mol L(-1) Ag(+) with the detection limit as low as 2.8×10(-12) mol L(-1). The response time of the sensor was ~150 s, with a RSD% of 0.4% (for 1.0×10(-6) mol L(-1), n=7). The optode could be regenerated by 0.2 mol L(-1) HCl solution. The interferences of potential interfering ions were studied. It was shown that the new optode was very selective to silver ions and had no significant response to common ions such as Mn(2+), Cd(2+), Ni(2+), Hg(2+), and Co(2+). It can be claimed that the sensor can specifically detect silver ions. The sensor was successfully applied for the determination of silver ions in different real samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Highly sensitive trivalent copper chelate–luminol chemiluminescence system for capillary electrophoresis chiral separation and determination of ofloxacin enantiomers in urine samples

    Directory of Open Access Journals (Sweden)

    Hao-Yue Xie

    2014-12-01

    Full Text Available A simple, fast and sensitive capillary electrophoresis (CE strategy combined with chemiluminescence (CL detection for analysis of ofloxacin (OF enantiomers was established in the present work. Sulfonated β-cyclodextrin (β-CD was used as the chiral additive being added into the running buffer of luminol–diperiodatocuprate (III (K5[Cu(HIO62], DPC chemiluminescence system. Under the optimum conditions, the proposed method was successfully applied to separation and analysis of OF enantiomers with the detection limits (S/N=3 of 8.0 nM and 7.0 nM for levofloxacin and dextrofloxacin, respectively. The linear ranges were both 0.010–100 μM. The method was utilized for analyzing OF in urine; the results obtained were satisfactory and recoveries were 89.5–110.8%, which demonstrated the reliability of this method. This approach can also be further extended to analyze different commercial OF medicines.

  6. Application of ionic liquid-based dispersive liquid phase microextraction for highly sensitive simultaneous determination of three endocrine disrupting compounds in food packaging.

    Science.gov (United States)

    Wang, Lingling; Zhang, Danfeng; Xu, Xu; Zhang, Lei

    2016-04-15

    Ionic liquid (IL) dispersive liquid-liquid microextraction (DLLME) method was successfully developed for extracting three endocrine disrupting compounds (EDCs) (bisphenol A, bisphenol AF and bisphenol AP) from the food packaging. 1-Octyl-3-methylimidazoliumhexafluorophosphate ([C8MIM][PF6]) was selected as extraction solution. The extraction procedure did not require a dispersive solvent. Three EDCs extraction kinetics were found to be very fast and the equilibrium was attained within 3.0 min following the pseudo-first-order model. The H-bonding and hydrophobic interactions play an important role in the partitioning of EDCs into IL from aqueous solution. The recovered IL could be reused for three runs without significant loss of extraction efficiencies. The spiked recoveries of three targets in food packaging were in the range of 97.8-103.1%. The limits of detection ranged from 0.50 to 1.50 ng mL(-1) (S/N=3). As a result, this method has been successfully applied for the sensitive detection of three EDCs in real samples.

  7. High sensitivity knitted fabric strain sensors

    Science.gov (United States)

    Xie, Juan; Long, Hairu; Miao, Menghe

    2016-10-01

    Wearable sensors are increasingly used in smart garments for detecting and transferring vital signals and body posture, movement and respiration. Existing fabric strain sensors made from metallized yarns have low sensitivity, poor comfort and low durability to washing. Here we report a knitted fabric strain sensor made from a cotton/stainless steel (SS) fibre blended yarn which shows much higher sensitivity than sensors knitted from metallized yarns. The fabric feels softer than pure cotton textiles owing to the ultrafine stainless steel fibres and does not lose its electrical property after washing. The reason for the high sensitivity of the cotton/SS knitted fabric sensor was explored by comparing its sensing mechanism with the knitted fabric sensor made from metallized yarns. The results show that the cotton/SS yarn-to-yarn contact resistance is highly sensitive to strain applied to hooked yarn loops.

  8. Salt sensitivity in chickpea is determined by sodium toxicity.

    Science.gov (United States)

    Khan, Hammad A; Siddique, Kadambot H M; Colmer, Timothy D

    2016-09-01

    Salt sensitivity in chickpea is determined by Na(+) toxicity, whereas relatively high leaf tissue concentrations of Cl(-) were tolerated, and the osmotic component of 60-mM NaCl was not detrimental. Chickpea (Cicer arietinum L.) is sensitive to salinity. This study dissected the responses of chickpea to osmotic and ionic components (Na(+) and/or Cl(-)) of salt stress. Two genotypes with contrasting salt tolerances were exposed to osmotic treatments (-0.16 and -0.29 MPa), Na(+)-salts, Cl(-)-salts, or NaCl at 0, 30, or 60 mM for 42 days and growth, tissue ion concentrations and leaf gas-exchange were assessed. The osmotic treatments and Cl(-)-salts did not affect growth, whereas Na(+)-salts and NaCl treatments equally impaired growth in either genotype. Shoot Na(+) and Cl(-) concentrations had markedly increased, whereas shoot K(+) had declined in the NaCl treatments, but both genotypes had similar shoot concentrations of each of these individual ions after 14 and 28 days of treatments. Genesis836 achieved higher net photosynthetic rate (64-84 % of control) compared with Rupali (35-56 % of control) at equivalent leaf Na(+) concentrations. We conclude that (1) salt sensitivity in chickpea is determined by Na(+) toxicity, and (2) the two contrasting genotypes appear to differ in 'tissue tolerance' of high Na(+). This study provides a basis for focus on Na(+) tolerance traits for future varietal improvement programs for salinity tolerance in chickpea.

  9. Development of a specific and highly sensitive optical chemical sensor for determination of Hg(II) based on a new synthesized ionophore.

    Science.gov (United States)

    Firooz, Ali R; Ensafi, Ali A; Karimi, K; Sharghi, H

    2013-10-01

    A novel optode for determination of Hg(II) ions is developed based on immobilization of a recently synthesized ionophore, 7-(1H-imidazol-1-ylmethyl)-5,6,7,8,9,10-hexahydro-2H-1,13,4,7,10 benzodioxatriaza cyclopentadecine-3,11(4H,12H)-dione, in a PVC membrane. Dioctyl sebacate was used as a plasticizer, sodium tetraphenylborate as an anionic additive and ETH5294 as a chromoionophore. The response of the optode was based on the complexation of Hg(II) with the ionophore in the membrane phase, resulting an ion exchange process between Hg(II) in the sample solution and H(+) in the membrane. The effects of pH and amounts of the ionophore, chromoionophore, ionic additive and type of plasticizer on the optode response were investigated. The selectivity of the optode was studied in the present of several cations. The optode has a linear response to Hg(II) in the range of 7.2×10(-13)-4.7×10(-4) mol L(-1) with detection limit of 0.18 pmol L(-1). The optode was successfully applied to the determination of Hg(II) in real samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. A novel 2-(2-Formyl-4-methyl-phenoxy)-N-phenyl-acetamide-based fluorescence turn-on chemosensor for selenium determination with high selectivity and sensitivity

    Science.gov (United States)

    Song, Cairui; Fei, Qiang; Shan, Hongyan; Feng, Guodong; Cui, Minghui; Liu, Yameng; Huan, Yanfu

    2013-12-01

    A novel turn-on fluorescent chemosensor, 2-(2-Formyl-4-methyl-phenoxy)-N-phenyl-acetamide (FMPPA) was designed and synthesized, and its photophysical properties were characterized. Upon coordination with Se (IV), the chemosensor showed incredible fluorescence enhancement (turn-on), other alkali, alkaline earth, transitional metal ions, and common anions including Li+, Na+, K+, Rb+, Cs+, Be2+, Mg2+, Ca2+, Sr2+, Ba2+, Ni2+, Cu2+, Cd2+, Zn2+, Mn2+, As3+, Pt4+, V5+, Fe3+, Mo6+, Al3+, CO32-, Cl-, SCN-, AC-, NO3-, F-, SO42- had no significant interference on Se (IV) determination. The chemosensor exhibits a dynamic response range for Se (IV) from 3.32 × 10-7 to 2.63 × 10-6 M, with a detection limit of 9.38 × 10-9 M (3σ).

  11. Highly sensitive determination of polycyclic aromatic hydrocarbons in ambient air dust by gas chromatography-mass spectrometry after molecularly imprinted polymer extraction.

    Science.gov (United States)

    Krupadam, Reddithota J; Bhagat, Bhagyashree; Khan, Muntazir S

    2010-08-01

    A method based on solid--phase extraction with a molecularly imprinted polymer (MIP) has been developed to determine five probable human carcinogenic polycyclic aromatic hydrocarbons (PAHs) in ambient air dust by gas chromatography-mass spectrometry (GC-MS). Molecularly imprinted poly(vinylpyridine-co-ethylene glycol dimethacrylate) was chosen as solid-phase extraction (SPE) material for PAHs. The conditions affecting extraction efficiency, for example surface properties, concentration of PAHs, and equilibration times were evaluated and optimized. Under optimum conditions, pre-concentration factors for MIP-SPE ranged between 80 and 93 for 10 mL ambient air dust leachate. PAHs recoveries from MIP-SPE after extraction from air dust were between 85% and 97% and calibration graphs of the PAHs showed a good linearity between 10 and 1000 ng L(-1) (r = 0.99). The extraction efficiency of MIP for PAHs was compared with that of commercially available SPE materials--powdered activated carbon (PAC) and polystyrene-divinylbenzene resin (XAD)--and it was shown that the extraction capacity of the MIP was better than that of the other two SPE materials. Organic matter in air dust had no effect on MIP extraction, which produced a clean extract for GC-MS analysis. The detection limit of the method proposed in this article is 0.15 ng L(-1) for benzo[a]pyrene, which is a marker molecule of air pollution. The method has been applied to the determination of probable carcinogenic PAHs in air dust of industrial zones and satisfactory results were obtained.

  12. Highly sensitive determination of polycyclic aromatic hydrocarbons in ambient air dust by gas chromatography-mass spectrometry after molecularly imprinted polymer extraction

    Energy Technology Data Exchange (ETDEWEB)

    Krupadam, Reddithota J.; Bhagat, Bhagyashree; Khan, Muntazir S. [National Environmental Engineering Research Institute, Nagpur (India)

    2010-08-15

    A method based on solid-phase extraction with a molecularly imprinted polymer (MIP) has been developed to determine five probable human carcinogenic polycyclic aromatic hydrocarbons (PAHs) in ambient air dust by gas chromatography-mass spectrometry (GC-MS). Molecularly imprinted poly(vinylpyridine-co-ethylene glycol dimethacrylate) was chosen as solid-phase extraction (SPE) material for PAHs. The conditions affecting extraction efficiency, for example surface properties, concentration of PAHs, and equilibration times were evaluated and optimized. Under optimum conditions, pre-concentration factors for MIP-SPE ranged between 80 and 93 for 10 mL ambient air dust leachate. PAHs recoveries from MIP-SPE after extraction from air dust were between 85% and 97% and calibration graphs of the PAHs showed a good linearity between 10 and 1000 ng L{sup -1} (r=0.99). The extraction efficiency of MIP for PAHs was compared with that of commercially available SPE materials - powdered activated carbon (PAC) and polystyrene-divinylbenzene resin (XAD) - and it was shown that the extraction capacity of the MIP was better than that of the other two SPE materials. Organic matter in air dust had no effect on MIP extraction, which produced a clean extract for GC-MS analysis. The detection limit of the method proposed in this article is 0.15 ng L{sup -1} for benzo[a]pyrene, which is a marker molecule of air pollution. The method has been applied to the determination of probable carcinogenic PAHs in air dust of industrial zones and satisfactory results were obtained. (orig.)

  13. High sensitivity optically pumped quantum magnetometer.

    Science.gov (United States)

    Tiporlini, Valentina; Alameh, Kamal

    2013-01-01

    Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz(½) over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz(½) in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz.

  14. APOBEC3F determinants of HIV-1 Vif sensitivity.

    Science.gov (United States)

    Land, Allison M; Shaban, Nadine M; Evans, Leah; Hultquist, Judd F; Albin, John S; Harris, Reuben S

    2014-11-01

    HIV-1 Vif counteracts restrictive APOBEC3 proteins by targeting them for proteasomal degradation. To determine the regions mediating sensitivity to Vif, we compared human APOBEC3F, which is HIV-1 Vif sensitive, with rhesus APOBEC3F, which is HIV-1 Vif resistant. Rhesus-human APOBEC3F chimeras and amino acid substitution mutants were tested for sensitivity to HIV-1 Vif. This approach identified the α3 and α4 helices of human APOBEC3F as important determinants of the interaction with HIV-1 Vif.

  15. Aluminum nanocantilevers for high sensitivity mass sensors

    DEFF Research Database (Denmark)

    Davis, Zachary James; Boisen, Anja

    2005-01-01

    We have fabricated Al nanocantilevers using a simple, one mask contact UV lithography technique with lateral and vertical dimensions under 500 and 100 nm, respectively. These devices are demonstrated as highly sensitive mass sensors by measuring their dynamic properties. Furthermore, it is shown ...

  16. Nonclassical characteristic functions for highly sensitive measurements

    CERN Document Server

    Richter, T; Richter, Th.

    2007-01-01

    Characteristic functions are shown to be useful for highly sensitive measurements. Redistributions of motional Fock states of a trapped atom can be directly monitored via the most fragile nonclassical part of the characteristic function. The method can also be used for decoherence measurements in optical quantum-information systems.

  17. Sensitive fluorimetric determination of gentamicin sulfate in biological matrices using solid-phase extraction, pre-column derivatization with 9-fluorenylmethyl chloroformate and reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Stead, D A; Richards, R M

    1996-01-26

    A high-performance liquid chromatographic method is described for the determination of gentamicin in bacterial culture medium or plasma with increased sensitivity and improved separation of the C1 component. Gentamicin was extracted from the biological matrix with high efficiency using carboxypropyl (CBA)-bonded silica. Derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by C18 reversed-phase chromatography allowed the fluorimetric detection of gentamicins C1, C1a and C2. A fourth component, considered to be gentamicin C2a, was partially resolved from the C2 peak. Optimal conditions for the extraction and derivatization of gentamicin are described. The detection limit was below 50 micrograms/l, the assay was linear to 5 mg/l and showed good reproducibility. It is concluded that pre-column derivatization with FMOC-Cl substantially improves the analysis of gentamicin compared with present methods based on reaction with o-phthaldialdehyde.

  18. 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.

    Science.gov (United States)

    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.

  19. Sensitive and background-free determination of thiols from wastewater samples by MOF-5 extraction coupled with high-performance liquid chromatography with fluorescence detection using a novel fluorescence probe of carbazole-9-ethyl-2-maleimide.

    Science.gov (United States)

    Lv, Zhengxian; Sun, Zhiwei; Song, Cuihua; Lu, Shuaimin; Chen, Guang; You, Jinmao

    2016-12-01

    A sensitive and background-free pre-column derivatization method for the determination of thiol compounds using metal-organic framework material (MOF-5) as dispersive solid-phase extraction (DSPE) adsorbent followed by high-performance liquid chromatography fluorescence detection (HPLC-FLD) has been developed. In this paper, a novel labeling reagent, carbazole-9-ethyl-2-maleimide(CAEM), was synthesized and reacted with thiols at 40°C for 10min in the presence of PBS buffer (0.02mol/L, pH 7.5). Interestingly, CAEM itself had no fluorescence, while its derivatives exhibited intense fluorescence with an excitation maximum at λex 274nm and an emission maximum at λem 363nm, which greatly reduced the background interference and improved the sensitivity of the method. Furthermore, the MOF-5 was prepared and used as DSPE adsorbent for the selective adsorption of thiols from wastewater sample. Under the optimized experimental conditions, an excellent linearity for all analytes over their concentration ranges of 0.01-1.0μmol/L (R(2)>0.9986)were obtained with the limit of detection (LOD) ranging from 8 to 17.1pmol/L for nine tested thiols. The feasibility of this method for the determination of thiols in wastewater samples had been evaluated and satisfactory average recoveries (n=3) were achieved with the range of 86.6-98.5%.

  20. Highly sensitive voltammetric sensor based on immobilization of bisphosphoramidate-derivative and quantum dots onto multi-walled carbon nanotubes modified gold electrode for the electrocatalytic determination of olanzapine

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi-Behzad, Leila [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Gholivand, Mohammad Bagher, E-mail: mbgholivand@yahoo.com [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Shamsipur, Mojtaba [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Gholivand, Khodayar [Department of Chemistry, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Barati, Ali [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Gholami, Akram [Department of Chemistry, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2016-03-01

    In the present paper, a new bisphosphoramidate derivative compound, 1, 4-bis(N-methyl)-benzene-bis(N-phenyl, N-benzoylphosphoramidate) (BMBPBP), was synthesized and used as a mediator for the electrocatalytic oxidation of olanzapine. The electro-oxidation of olanzapine at the surface of the BMBPBP/CdS-quantum dots/multi-walled carbon nanotubes (BMBPBP/CdS-QDs/MWCNTs) modified gold electrode was studied using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. This sensor showed an excellent electrocatalytic oxidation activity toward olanzapine at less positive potential, pronounced current response, and good sensitivity. The diffusion coefficient and kinetic parameters (such as electron transfer coefficient and the heterogeneous rate constant) were determined for olanzapine oxidation, using the electrochemical approaches. Surface morphology and electrochemical properties of the prepared modified electrode were investigated by scanning electron microscopy (SEM), cyclic voltammetry and electrochemical impedance spectroscopy techniques. The hydrodynamic amperometry at rotating modified electrode at constant potential versus reference electrode was used for detection of olanzapine. Under optimized conditions, the calibration plot was linear in the concentration range of 20 nM to 100 μM and detection limit was found to be 6 nM. The proposed method was successfully applied to the determination of olanzapine in pharmaceuticals and human serum samples. - Highlights: • A highly sensitive sensor for OLZ determination was developed. • The sensor constructed based on immobilization of BMBPBP on CdS-QDs/MWCNTs Au electrode • The morphology of the modified electrode was examined by SEM. • The prepared sensor shows stable electrochemical behavior at a wide pH range. • The proposed sensor is used for trace determination of OLZ in real samples.

  1. Sensitive determination of trace urinary 3-hydroxybenzo[a]pyrene using ionic liquids-based dispersive liquid-liquid microextraction followed by chemical derivatization and high performance liquid chromatography-high resolution tandem mass spectrometry.

    Science.gov (United States)

    Hu, Huan; Liu, Baizhan; Yang, Jun; Lin, Zuomin; Gan, Wuer

    2016-08-01

    3-Hydroxybenzo[a]pyrene (3-OHBaP) is widely used as a biomarker for assessing carcinogenic benzo[a]pyrene exposure risks. However, monitoring urinary 3-OHBaP suffers from an insufficient sensitivity due to the pg/mL level in urine excretion. In this study, a sensitive method for determination trace urinary 3-OHBaP was developed, involving enzymatic hydrolysis of the glucuronide and sulfate conjugates, ionic liquids dispersive liquid-liquid microextraction (IL-DLLME) enrichment, derivatization with dansyl chloride and HPLC-HRMS/MS analysis in the positive ion mode. Using IL-DLLME makes the enrichment of trace 3-OHBaP very simple, time-saving, efficiency and environmentally-friendly. To enhanced HPLC-HRMS/MS response, an MS-friendly dansyl group was introduced to increase the ionization and fragmentation efficiency. The optimal IL-DLLME extraction parameters and derivatization reaction conditions were investigated. Good linearity was obtained over a concentration range of 0.6-50.0pg/mL with correlation coefficients (r(2)) of 0.9918. The limit of detection (LOD) and limit of quantification (LOQ) values were 0.2pg/mL and 0.58pg/mL, respectively. The recoveries were 92.0±4.2% with the intra-day and inter-day RSD values ranged from 2.2% to 3.8% and from 3.3% to 6.8%, respectively. The proposed IL-DLLME-Dansylation-HPLC-HRMS/MS method was successfully applied to determine urinary 3-OHBaP of non-occupational exposed smokers and nonsmokers.

  2. Highly Energetic, Low Sensitivity Aromatic Peroxy Acids.

    Science.gov (United States)

    Gamage, Nipuni-Dhanesha H; Stiasny, Benedikt; Stierstorfer, Jörg; Martin, Philip D; Klapötke, Thomas M; Winter, Charles H

    2016-02-18

    The synthesis, structure, and energetic materials properties of a series of aromatic peroxy acid compounds are described. Benzene-1,3,5-tris(carboperoxoic) acid is a highly sensitive primary energetic material, with impact and friction sensitivities similar to those of triacetone triperoxide. By contrast, benzene-1,4-bis(carboperoxoic) acid, 4-nitrobenzoperoxoic acid, and 3,5-dinitrobenzoperoxoic acid are much less sensitive, with impact and friction sensitivities close to those of the secondary energetic material 2,4,6-trinitrotoluene. Additionally, the calculated detonation velocities of 3,5-dinitrobenzoperoxoic acid and 2,4,6-trinitrobenzoperoxoic acid exceed that of 2,4,6-trinitrotoluene. The solid-state structure of 3,5-dinitrobenzoperoxoic acid contains intermolecular O-H⋅⋅⋅O hydrogen bonds and numerous N⋅⋅⋅O, C⋅⋅⋅O, and O⋅⋅⋅O close contacts. These attractive lattice interactions may account for the less sensitive nature of 3,5-dinitrobenzoperoxoic acid.

  3. Data Acquisition Protocol for Determining Embedded Sensitivity Functions.

    Science.gov (United States)

    Meyer, Janette J; Adams, Douglas E; Silvers, Janene

    2016-04-20

    The effectiveness of many structural health monitoring techniques depends on the placement of sensors and the location of input forces. Algorithms for determining optimal sensor and forcing locations typically require data, either simulated or measured, from the damaged structure. Embedded sensitivity functions provide an approach for determining the best available sensor location to detect damage with only data from the healthy structure. In this video and manuscript, the data acquisition procedure and best practices for determining the embedded sensitivity functions of a structure is presented. The frequency response functions used in the calculation of the embedded sensitivity functions are acquired using modal impact testing. Data is acquired and representative results are shown for a residential scale wind turbine blade. Strategies for evaluating the quality of the data being acquired are provided during the demonstration of the data acquisition process.

  4. Sensitive determination of thiols in wine samples by a stable isotope-coded derivatization reagent d0/d4-acridone-10-ethyl-N-maleimide coupled with high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry analysis.

    Science.gov (United States)

    Lv, Zhengxian; You, Jinmao; Lu, Shuaimin; Sun, Weidi; Ji, Zhongyin; Sun, Zhiwei; Song, Cuihua; Chen, Guang; Li, Guoliang; Hu, Na; Zhou, Wu; Suo, Yourui

    2017-03-31

    As the key aroma compounds, varietal thiols are the crucial odorants responsible for the flavor of wines. Quantitative analysis of thiols can provide crucial information for the aroma profiles of different wine styles. In this study, a rapid and sensitive method for the simultaneous determination of six thiols in wine using d0/d4-acridone-10-ethyl-N-maleimide (d0/d4-AENM) as stable isotope-coded derivatization reagent (SICD) by high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) has been developed. Quantification of thiols was performed by using d4-AENM labeled thiols as the internal standards (IS), followed by stable isotope dilution HPLC-ESI-MS/MS analysis. The AENM derivatization combined with multiple reactions monitoring (MRM) not only allowed trace analysis of thiols due to the extremely high sensitivity, but also efficiently corrected the matrix effects during HPLC-MS/MS and the fluctuation in MS/MS signal intensity due to instrument. The obtained internal standard calibration curves for six thiols were linear over the range of 25-10,000pmol/L (R(2)≥0.9961). Detection limits (LODs) for most of analytes were below 6.3pmol/L. The proposed method was successfully applied for the simultaneous determination of six kinds of thiols in wine samples with precisions ≤3.5% and recoveries ≥78.1%. In conclusion, the developed method is expected to be a promising tool for detection of trace thiols in wine and also in other complex matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Quantitative determination of fucoidan using polyion-sensitive membrane electrodes.

    Science.gov (United States)

    Kim, Ji Min; Nguyen, Loc; Barr, Mary Frances; Morabito, Michael; Stringer, Damien; Fitton, J Helen; Mowery, Kelly A

    2015-06-02

    The use of polyanion and polycation-sensitive membrane electrodes to detect five different preparations of fucoidan is described. Unlike linear polyanionic molecules previously measured with polymer membrane-based electrochemical sensors, fucoidans from marine brown algae are all highly branched, sulfated polysaccharides with varying charge densities and structures, depending on the species of seaweed, method of extraction used and extent of purification. When tridodecylmethylammonium (TDMA) was used as the ion-exchanger, a large, non-equilibrium EMF response was observed over a concentration range of 0.5-50 μg mL(-1) fucoidan. Fucoidan was also measured by titration with polycationic protamine, using a dinonylnaphthalene sulfonate (DNNS)-doped membrane electrode as the potentiometric endpoint detector. Potentiometric titration was used to determine the binding ratio between protamine and fucoidan at the neutralization endpoint for each fucoidan preparation. This binding ratio was then used to successfully determine the fucoidan content of commercially available nutritional supplements. Fucoidan was also measured in undiluted blood serum, demonstrating that this method may be applicable for measuring fucoidan for clinical applications.

  6. Determination of amantadine and rimantadine using a sensitive fluorescent probe

    Science.gov (United States)

    Wang, Guang-Quan; Qin, Yan-Fang; Du, Li-Ming; Li, Jun-Fei; Jing, Xu; Chang, Yin-Xia; Wu, Hao

    2012-12-01

    Amantadine hydrochloride (AMA) and rimantadine hydrochloride (RIM) are non-fluorescent in aqueous solutions. This property makes their determination through direct fluorescent method difficult. The competing reactions and the supramolecular interaction mechanisms between the two drugs and coptisine (COP) as they fight for occupancy of the cucurbit[7]uril (CB[7]) cavity, were studied using spectrofluorimetry, 1H NMR, and molecular modeling calculations. Based on the significant quenching of the supramolecular complex fluorescence intensity, a fluorescent probe method of high sensitivity and selectivity was developed to determine AMA or RIM in their pharmaceutical dosage forms and in urine samples with good precision and accuracy. The linear range of the method was from 0.0040 to 1.0 μg mL-1 with a detection limit ranging from 0.0012 to 0.0013 μg mL-1. This shows that the proposed method has promising potential for therapeutic monitoring and pharmacokinetics and for clinical application.

  7. Graphene/polydopamine-modified polytetrafluoroethylene microtube for the sensitive determination of three active components in Fructus Psoraleae by online solid-phase microextraction with high-performance liquid chromatography.

    Science.gov (United States)

    Zhang, Wenpeng; Zhou, Wei; Chen, Zilin

    2014-11-01

    Determination of bioactive compounds in traditional Chinese medicines and biological samples is usually interfered with by coexisting components in matrices. In this work, we prepared novel multilayer functional graphene/polydopamine-modified polytetrafluoroethylene microtube for selective solid-phase microextraction of three bioactive compounds in Fructus Psoraleae. Functional graphene/polydopamine-modified polytetrafluoroethylene microtube showed good extraction efficiency toward bavachin, isobavachalcone, and bavachinin; enrichment from 357- to 737-fold was obtained for these compounds. For qualitative analysis, an online solid-phase microextraction with high-performance liquid chromatography method was developed, which showed low limits of detection of 0.02 ng/mL by using UV detection, which is significantly more sensitive than previously reported methods. The proposed method has been used to determine bavachin, isobavachalcone, and bavachinin in Fructus Psoraleae, the contents of three compounds were quantified to be 64.0, 324.0, and 384.5 μg/g; recoveries were 93.4-101.1%. The proposed method has also been applied to determine bavachin, isobavachalcone, and bavachinin in rat plasma samples after oral administration of Fructus Psoraleae. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. High-sensitive cardiac troponin T

    Institute of Scientific and Technical Information of China (English)

    Ru-Yi Xu; Xiao-Fa Zhu; Ye Yang; Ping Ye

    2013-01-01

    Cardiac troponin is the preferred biomarker for the diagnosis of acute myocardial infarction (AMI). The recent development of a high-sensitive cardiac troponin T (hs-cTnT) assay permits detection of very low levels of cTnT. Using the hs-cTnT assay improves the overall diagnostic accuracy in patients with suspected AMI, while a negative result also has a high negative predictive value. The gain in sensitivity may be particularly important in patients with a short duration from symptom onset to admission. Measurement of cardiac troponin T with the hs-cTnT assay may provide strong prognostic information in patients with acute coronary syndromes, stable coronary artery disease, heart failure and even in the general population; however, increased sensitivity comes at a cost of decreased specificity. Serial testing, as well as clinical context and co-existing diseases, are likely to become increasingly important for the interpretation of hs-cTnT assay results.

  9. Determination of temperature of moving surface by sensitivity analysis

    CERN Document Server

    Farhanieh, B

    2002-01-01

    In this paper sensitivity analysis in inverse problem solutions is employed to estimate the temperature of a moving surface. Moving finite element method is used for spatial discretization. Time derivatives are approximated using Crank-Nicklson method. The accuracy of the solution is assessed by simulation method. The convergence domain is investigated for the determination of the temperature of a solid fuel.

  10. Application and optimization of microwave-assisted extraction and dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for sensitive determination of polyamines in turkey breast meat samples.

    Science.gov (United States)

    Bashiry, Moein; Mohammadi, Abdorreza; Hosseini, Hedayat; Kamankesh, Marzieh; Aeenehvand, Saeed; Mohammadi, Zaniar

    2016-01-01

    A novel method based on microwave-assisted extraction and dispersive liquid-liquid microextraction (MAE-DLLME) followed by high-performance liquid chromatography (HPLC) was developed for the determination of three polyamines from turkey breast meat samples. Response surface methodology (RSM) based on central composite design (CCD) was used to optimize the effective factors in DLLME process. The optimum microextraction efficiency was obtained under optimized conditions. The calibration graphs of the proposed method were linear in the range of 20-200 ng g(-1), with the coefficient determination (R(2)) higher than 0.9914. The relative standard deviations were 6.72-7.30% (n = 7). The limits of detection were in the range of 0.8-1.4 ng g(-1). The recoveries of these compounds in spiked turkey breast meat samples were from 95% to 105%. The increased sensitivity in using the MAE-DLLME-HPLC-UV has been demonstrated. Compared with previous methods, the proposed method is an accurate, rapid and reliable sample-pretreatment method.

  11. Simultaneous determination of l-tetrahydropalmatine and its active metabolites in rat plasma by a sensitive ultra-high-performance liquid chromatography with tandem mass spectrometry method and its application in a pharmacokinetic study.

    Science.gov (United States)

    Wang, Weihui; Liu, Jing; Zhao, Xiaoning; Peng, Yan; Wang, Nannan; Lee, David Y W; Dai, Ronghua

    2017-06-01

    A sensitive and reliable ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for simultaneous determination of l-tetrahydropalmatine (l-THP) and its active metabolites l-isocorypalmine (l-ICP) and L-corydalmine (l-CD) in rat plasma. The analytes were extracted by liquid-liquid extraction and separated on a Bonshell ASB C18 column (2.1 × 100 mm; 2.7 μm; Agela) using acetonitrile-formic acid aqueous as mobile phase at a flow rate of 0.2 mL/min in gradient mode. The method was validated over the concentration range of 4.00-2500 ng/mL for l-THP, 0.400-250 ng/mL for l-ICP and 1.00-625 ng/mL for l-CD. Intra- and inter-day accuracy and precision were within the acceptable limits of 0.99 for all analytes. The quantitative method was successfully applied for simultaneous determination of l-THP and its active metabolites in a pharmacokinetic study after oral administration with l-THP at a dose of 15 mg/kg to rats. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Photodetector having high speed and sensitivity

    Science.gov (United States)

    Morse, Jeffrey D.; Mariella, Jr., Raymond P.

    1991-01-01

    The present invention provides a photodetector having an advantageous combination of sensitivity and speed; it has a high sensitivity while retaining high speed. In a preferred embodiment, visible light is detected, but in some embodiments, x-rays can be detected, and in other embodiments infrared can be detected. The present invention comprises a photodetector having an active layer, and a recombination layer. The active layer has a surface exposed to light to be detected, and comprises a semiconductor, having a bandgap graded so that carriers formed due to interaction of the active layer with the incident radiation tend to be swept away from the exposed surface. The graded semiconductor material in the active layer preferably comprises Al.sub.1-x Ga.sub.x As. An additional sub-layer of graded In.sub.1-y Ga.sub.y As may be included between the Al.sub.1-x Ga.sub.x As layer and the recombination layer. The recombination layer comprises a semiconductor material having a short recombination time such as a defective GaAs layer grown in a low temperature process. The recombination layer is positioned adjacent to the active layer so that carriers from the active layer tend to be swept into the recombination layer. In an embodiment, the photodetector may comprise one or more additional layers stacked below the active and recombination layers. These additional layers may include another active layer and another recombination layer to absorb radiation not absorbed while passing through the first layers. A photodetector having a stacked configuration may have enhanced sensitivity and responsiveness at selected wavelengths such as infrared.

  13. High sensitivity troponin and valvular heart disease.

    Science.gov (United States)

    McCarthy, Cian P; Donnellan, Eoin; Phelan, Dermot; Griffin, Brian P; Sarano, Maurice Enriquez-; McEvoy, John W

    2017-01-16

    Blood-based biomarkers have been extensively studied in a range of cardiovascular diseases and have established utility in routine clinical care, most notably in the diagnosis of acute coronary syndrome (e.g., troponin) and the management of heart failure (e.g., brain-natriuretic peptide). The role of biomarkers is less well established in the management of valvular heart disease (VHD), in which the optimal timing of surgical intervention is often challenging. One promising biomarker that has been the subject of a number of recent VHD research studies is high sensitivity troponin (hs-cTn). Novel high-sensitivity assays can detect subclinical myocardial damage in asymptomatic individuals. Thus, hs-cTn may have utility in the assessment of asymptomatic patients with severe VHD who do not have a clear traditional indication for surgical intervention. In this state-of-the-art review, we examine the current evidence for hs-cTn as a potential biomarker in the most commonly encountered VHD conditions, aortic stenosis and mitral regurgitation. This review provides a synopsis of early evidence indicating that hs-cTn has promise as a biomarker in VHD. However, the impact of its measurement on clinical practice and VHD outcomes needs to be further assessed in prospective studies before routine clinical use becomes a reality.

  14. Automated online optical biosensing system for continuous real-time determination of microcystin-LR with high sensitivity and specificity: early warning for cyanotoxin risk in drinking water sources.

    Science.gov (United States)

    Shi, Han-Chang; Song, Bao-Dong; Long, Feng; Zhou, Xiao-Hong; He, Miao; Lv, Qing; Yang, Hai-Yang

    2013-05-07

    The accelerated eutrophication of surface water sources and climate change have led to an annual occurrence of cyanobacterial blooms in many drinking water resources. To minimize the health risks to the public, cyanotoxin detection methods that are rapid, sensitive, real time, and high frequency must be established. In this study, an innovative automated online optical biosensing system (AOBS) was developed for the rapid detection and early warning of microcystin-LR (MC-LR), one of the most toxic cyanotoxins and most frequently detected in environmental water. In this system, the capturing molecular MC-LR-ovalbumin (MC-LR-OVA) was covalently immobilized onto a biochip surface. By an indirect competitive detection mode, samples containing different concentrations of MC-LR were premixed with a certain concentration of fluorescence-labeled anti-MC-LR-mAb, which binds to MC-LR with high specificity. Then, the sample mixture was pumped onto the biochip surface, and a higher concentration of MC-LR led to less fluorescence-labeled antibody bound onto the biochip surface and thus to lower fluorescence signal. The quantification of MC-LR ranges from 0.2 to 4 μg/L, with a detection limit determined as 0.09 μg/L. The high specificity and selectivity of the sensor were evaluated in terms of its response to a number of potentially interfering cyanotoxins. Potential interference of the environmental sample matrix was assessed by spiked samples, and the recovery of MC-LR ranged from 90 to 120% with relative standard deviation values online analysis that satisfies the high demand for ensuring the safety of drinking water sources. The AOBS can also serve as early warning system for accidental or intentional water pollution.

  15. Development and validation of a rapid and high-sensitivity liquid chromatography-tandem mass spectrometry assay for the determination of neostigmine in small-volume beagle dog plasma and its application to a pharmacokinetic study.

    Science.gov (United States)

    Cao, Di; Li, Wenxue; Zhao, Xin; Ye, Xiaolan; Sun, Fanlu; Li, Jinying; Song, Fenyun; Fan, Guorong

    2014-03-01

    A simple, rapid and high sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of neostigmine in small-volume beagle dog plasma was developed to assess the plasma pharmacokinetics of neostigmine. After protein precipitation in a Sirocco 96-well filtration plate, the filtrate was directly injected into the LC-MS/MS system. The analytes were separated on a Hanbon Hedera CN column (100 × 4.6 mm, 5 µm) with a mobile phase composed of methanol-water (60:40, v/v) and the water containing 0.01% formic acid at a flow rate of 0.6mL/min, with a split ratio of 1:1 flowing 300 μL into the mass spectrometer. The run time was 3 min. Detection was accomplished by electrospray ionization source in multiple reactions monitoring mode with the precursor-to-product ion transitions m/z 223.0 → 72.0 and 306.0 → 140.0 for neostigmine and anisodamine (internal standard), respectively. The method was sensitive with a lower limit of quantitation of 0.1 ng/mL, and good linearity in the range 0.1-100ng/mL for neostigmine (r ≥ 0.998). All the validation data, such as accuracy, intra-run and inter-run precision, were within the required limits. The method was successfully applied to pharmacokinetic study of neostigmine methylsulfate injection in beagle dogs.

  16. [Procedure for determination of individual sensitivity to antitumor drugs].

    Science.gov (United States)

    Abduvaliev, A A; Gil'dieva, M S; Tatarskiĭ, V P

    2006-05-01

    The present paper proposes to employ the cultured tumor cells of the breast and chick fibroblasts after long-term cultivation (for above 24 days) to determine their individual drug sensitivity and, as a criterion of cell damage, to use the percent of destruction of the cell layer formed in the wells 24 hours after drug insertion. It also presents the comparative results of tests of 2 cellular models that have been used to determine the in vitro sensitivity of the cells of breast cancer and chick fibroblasts to melfalan and its complex compound with copper acetylacetonate - MOK*M. At the same time, the cytotoxic activity of MOK*M and melfalan against tumor cells has been not shown to differ greatly (16.02+/-1.85 and 15.71+/-0.65% cell layer destruction, respectively), but the same activity of MOK*M against the model of intact cells (chick fibroblasts) was much less (15.23+/-1.97%) than that of melfalan (95.39+/-1.11%). The test system proposed by the authors is of certain informative value and it may be used for the determination of the individual sensitivity of tumor cells to antitumor drugs.

  17. Highly Sensitive Electro-Optic Modulators

    Energy Technology Data Exchange (ETDEWEB)

    DeVore, Peter S [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    There are very important diagnostic and communication applications that receive faint electrical signals to be transmitted over long distances for capture. Optical links reduce bandwidth and distance restrictions of metal transmission lines; however, such signals are only weakly imprinted onto the optical carrier, resulting in low fidelity transmission. Increasing signal fidelity often necessitates insertion of radio-frequency (RF) amplifiers before the electro-optic modulator, but (especially at high frequencies) RF amplification results in large irreversible distortions. We have investigated the feasibility of a Sensitive and Linear Modulation by Optical Nonlinearity (SALMON) modulator to supersede RF-amplified modulators. SALMON uses cross-phase modulation, a manifestation of the Kerr effect, to enhance the modulation depth of an RF-modulated optical wave. This ultrafast process has the potential to result in less irreversible distortions as compared to a RF-amplified modulator due to the broadband nature of the Kerr effect. Here, we prove that a SALMON modulator is a feasible alternative to an RFamplified modulator, by demonstrating a sensitivity enhancement factor greater than 20 and significantly reduced distortion.

  18. A sensitive and accurate method for the determination of perfluoroalkyl and polyfluoroalkyl substances in human serum using a high performance liquid chromatography-online solid phase extraction-tandem mass spectrometry.

    Science.gov (United States)

    Yu, Chang Ho; Patel, Bhupendra; Palencia, Marilou; Fan, Zhihua Tina

    2017-01-13

    A selective, sensitive, and accurate analytical method for the measurement of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in human serum, utilizing LC-MS/MS (liquid chromatography-tandem mass spectrometry), was developed and validated according to the Centers for Disease Control and Prevention (CDC) guidelines for biological sample analysis. Tests were conducted to determine the optimal analytical column, mobile phase composition and pH, gradient program, and cleaning procedure. The final analytical column selected for analysis was an extra densely bonded silica-packed reverse-phase column (Agilent XDB-C8, 3.0×100mm, 3.5μm). Mobile phase A was an aqueous buffer solution containing 10mM ammonium acetate (pH=4.3). Mobile phase B was a mixture of methanol and acetonitrile (1:1, v/v). The gradient program was programmed by initiating a fast elution (%B, from 40 to 65%) between 1.0 and 1.5min, followed by a slow elution (%B: 65-80%) in the period of 1.5-7.5min. The cleanup procedures were augmented by cleaning with (1) various solvents (isopropyl alcohol, methanol, acetonitrile, and reverse osmosis-purified water); (2) extensive washing steps for the autosampler and solid phase extraction (SPE) cartridge; and (3) a post-analysis cleaning step for the whole system. Under the above conditions, the resolution and sensitivity were significantly improved. Twelve target PFASs were baseline-separated (2.5-7.0min) within a 10-min of acquisition time. The limits of detection (LODs) were 0.01ng/mL or lower for all of the target compounds, making this method 5 times more sensitive than previously published methods. The newly developed method was validated in the linear range of 0.01-50ng/mL, and the accuracy (recovery between 80 and 120%) and precision (RSD<20%) were acceptable at three spiked levels (0.25, 2.5, and 25ng/mL). The method development and validation results demonstrated that this method was precise, accurate, and robust, with high-throughput (∼10min per

  19. Heterogeneous catalysis in highly sensitive microreactors

    DEFF Research Database (Denmark)

    Olsen, Jakob Lind

    This thesis present a highly sensitive silicon microreactor and examples of its use in studying catalysis. The experimental setup built for gas handling and temperature control for the microreactor is described. The implementation of LabVIEW interfacing for all the experimental parts makes...... automated experiments and data collection possible. An argon ush at the O-rings (used to interface the silicon microreactor with the gas system), which was developed, is presented. It enables experiments with temperatures up to 400., and up to 500. for short periods of time. The CO oxidation reaction...... of adsorbates readily converted to methanol as the source of the transient increase in methanol production, is eliminated. A study of mass selected ruthenium nanoparticles from a magnetron-sputter gas-aggregation source, deposited in microreactors, is presented. It is, shown that CO methanation can be measured...

  20. High-sensitivity fiber optic acoustic sensors

    Science.gov (United States)

    Lu, Ping; Liu, Deming; Liao, Hao

    2016-11-01

    Due to the overwhelming advantages compared with traditional electronicsensors, fiber-optic acoustic sensors have arisen enormous interest in multiple disciplines. In this paper we present the recent research achievements of our group on fiber-optic acoustic sensors. The main point of our research is high sensitivity interferometric acoustic sensors, including Michelson, Sagnac, and Fabry-Pérot interferometers. In addition, some advanced technologies have been proposed for acoustic or acoustic pressure sensing such as single-mode/multimode fiber coupler, dual FBGs and multi-longitudinal mode fiber laser based acoustic sensors. Moreover, our attention we have also been paid on signal demodulation schemes. The intensity-based quadrature point (Q-point) demodulation, two-wavelength quadrature demodulation and symmetric 3×3 coupler methodare discussed and compared in this paper.

  1. High sensitive radiation detector for radiology dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Valente, M.; Malano, F. [Instituto de Fisica Enrique Gaviola, Oficina 102 FaMAF - UNC, Av. Luis Medina Allende, Ciudad Universitaria, 5000 Cordoba (Argentina); Molina, W.; Vedelago, J., E-mail: valente@famac.unc.edu.ar [Laboratorio de Investigaciones e Instrumentacion en Fisica Aplicada a la Medicina e Imagenes por Rayos X, Laboratorio 448 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina)

    2014-08-15

    Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, dose rate recorded and incident direction independence as well as linear dose response. This work presents the development and characterization of a novel Fricke gel system, based on modified chemical compositions making possible its application in clinical radiology. Properties of standard Fricke gel dosimeter for high dose levels are used as starting point and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose dependency, actually showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain a good enough dosimeter response for low dose levels. A suitable composition among those studied is selected as a good candidate for low dose level radiation dosimetry consisting on a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, xylenol orange and ultra-pure reactive grade water. Dosimeter samples are prepared in standard vials for its in phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated by typical kV X-ray tubes and calibrated Farmer type ionization chamber is used as reference to measure dose rates inside phantoms in at vials locations. Once sensitive material composition is already optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels. According to

  2. Comparison of Lipoprotein-Associated Phospholipase A2 and High Sensitive C-Reactive Protein as Determinants of Metabolic Syndrome in Subjects without Coronary Heart Disease: In Search of the Best Predictor

    Directory of Open Access Journals (Sweden)

    Mónica Acevedo

    2015-01-01

    Full Text Available High sensitivity C-reactive protein (hsCRP is a marker of metabolic syndrome (MS and cardiovascular (CV disease. Lipoprotein-associated phospholipase A2 (Lp-PLA2 also predicts CV disease. There are no reports comparing these markers as predictors of MS. Methods. Cross-sectional study comparing Lp-PLA2 and hsCRP as predictors of MS in asymptomatic subjects was carried out; 152 subjects without known atherosclerosis participated. Data were collected on demographics, cardiovascular risk factors, anthropometric and biochemical measurements, and hsCRP and Lp-PLA2 activity levels. A logistic regression analysis was performed with each biomarker and receiver operating characteristic (ROC curves were constructed for MS. Results. Mean age was 46 ± 11 years, and 38% of the subjects had MS. Mean Lp-PLA2 activity was 185 ± 48 nmol/mL/min, and mean hsCRP was 2.1 ± 2.2 mg/L. Subjects with MS had significantly higher levels of Lp-PLA2 (P=0.03 and hsCRP (P<0.0001 than those without MS. ROC curves showed that both markers predicted MS. Conclusion. Lp-PLA2 and hsCRP are elevated in subjects with MS. Both biomarkers were independent and significant predictors for MS, emphasizing the role of inflammation in MS. Further research is necessary to determine if inflammation predicts a higher risk for CV events in MS subjects.

  3. Comparison of Lipoprotein-Associated Phospholipase A2 and High Sensitive C-Reactive Protein as Determinants of Metabolic Syndrome in Subjects without Coronary Heart Disease: In Search of the Best Predictor

    Science.gov (United States)

    Acevedo, Mónica; Kramer, Verónica; Adasme, Marcela; Briones, Luisa

    2015-01-01

    High sensitivity C-reactive protein (hsCRP) is a marker of metabolic syndrome (MS) and cardiovascular (CV) disease. Lipoprotein-associated phospholipase A2 (Lp-PLA2) also predicts CV disease. There are no reports comparing these markers as predictors of MS. Methods. Cross-sectional study comparing Lp-PLA2 and hsCRP as predictors of MS in asymptomatic subjects was carried out; 152 subjects without known atherosclerosis participated. Data were collected on demographics, cardiovascular risk factors, anthropometric and biochemical measurements, and hsCRP and Lp-PLA2 activity levels. A logistic regression analysis was performed with each biomarker and receiver operating characteristic (ROC) curves were constructed for MS. Results. Mean age was 46 ± 11 years, and 38% of the subjects had MS. Mean Lp-PLA2 activity was 185 ± 48 nmol/mL/min, and mean hsCRP was 2.1 ± 2.2 mg/L. Subjects with MS had significantly higher levels of Lp-PLA2 (P = 0.03) and hsCRP (P < 0.0001) than those without MS. ROC curves showed that both markers predicted MS. Conclusion. Lp-PLA2 and hsCRP are elevated in subjects with MS. Both biomarkers were independent and significant predictors for MS, emphasizing the role of inflammation in MS. Further research is necessary to determine if inflammation predicts a higher risk for CV events in MS subjects. PMID:26089902

  4. High sensitivity field asymmetric ion mobility spectrometer

    Science.gov (United States)

    Chavarria, Mario A.; Matheoud, Alessandro V.; Marmillod, Philippe; Liu, Youjiang; Kong, Deyi; Brugger, Jürgen; Boero, Giovanni

    2017-03-01

    A high sensitivity field asymmetric ion mobility spectrometer (FAIMS) was designed, fabricated, and tested. The main components of the system are a 10.6 eV UV photoionization source, an ion filter driven by a high voltage/high frequency n-MOS inverter circuit, and a low noise ion detector. The ion filter electronics are capable to generate square waveforms with peak-to-peak voltages up to 1000 V at frequencies up to 1 MHz with adjustable duty cycles. The ion detector current amplifier has a gain up to 1012 V/A with an effective equivalent input noise level down to about 1 fA/Hz1/2 during operation with the ion filter at the maximum voltage and frequency. The FAIMS system was characterized by detecting different standard chemical compounds. Additionally, we investigated the use of a synchronous modulation/demodulation technique to improve the signal-to-noise ratio in FAIMS measurements. In particular, we implemented the modulation of the compensation voltage with the synchronous demodulation of the ion current. The analysis of the measurements at low concentration levels led to an extrapolated limit of detection for acetone of 10 ppt with an averaging time of 1 s.

  5. Determining Confounding Sensitivities In Eddy Current Thin Film Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gros, Ethan; Udpa, Lalita; Smith, James A.; Wachs, Katelyn

    2016-07-01

    Determining Confounding Sensitivities In Eddy Current Thin Film Measurements Ethan Gros, Lalita Udpa, Electrical Engineering, Michigan State University, East Lansing MI 48824 James A. Smith, Experiment Analysis, Idaho National Laboratory, Idaho Falls ID 83415 Eddy current (EC) techniques are widely used in industry to measure the thickness of non-conductive films on a metal substrate. This is done using a system whereby a coil carrying a high-frequency alternating current is used to create an alternating magnetic field at the surface of the instrument's probe. When the probe is brought near a conductive surface, the alternating magnetic field will induce ECs in the conductor. The substrate characteristics and the distance of the probe from the substrate (the coating thickness) affect the magnitude of the ECs. The induced currents load the probe coil affecting the terminal impedance of the coil. The measured probe impedance is related to the lift off between coil and conductor as well as conductivity of the test sample. For a known conductivity sample, the probe impedance can be converted into an equivalent film thickness value. The EC measurement can be confounded by a number of measurement parameters. It is the goal of this research to determine which physical properties of the measurement set-up and sample can adversely affect the thickness measurement. The eddy current testing is performed using a commercially available, hand held eddy current probe (ETA3.3H spring loaded eddy probe running at 8 MHz) that comes with a stand to hold the probe. The stand holds the probe and adjusts the probe on the z-axis to help position the probe in the correct area as well as make precise measurements. The signal from the probe is sent to a hand held readout, where the results are recorded directly in terms of liftoff or film thickness. Understanding the effect of certain factors on the measurements of film thickness, will help to evaluate how accurate the ETA3.3H spring

  6. Sensitive Determination of Epinephrine Using Kinetic Spectrophotometric Method

    Directory of Open Access Journals (Sweden)

    Atefah Ekhtesasi

    2016-03-01

    Full Text Available In this study, thionine – bromate as a sensitive reaction system using kinetic spectrophotometric method for the determination of epinephrine is proposed. The method is based on the catalytic effect of epinephrine on the selected reaction system. The change in absorbance was followed spectrophotometrically as a criterion of the oxidation reaction progress. The effective reaction variables were optimized. Under optimized experimental conditions, calibration curve was linear over the range 0.4 – 12.8 mg/l and the detection limit was 0.13 mg/l for five replicate determinations of blank signal. The interfering effect of various species was also investigated. The developed procedure was successfully applied for the determination of diclofenac in pharmaceutical and biological samples satisfactorily.

  7. Highly sensitive direct conversion ultrasound interferometer

    Science.gov (United States)

    Svitelskiy, Oleksiy; Grossmann, John; Suslov, Alexey

    2015-03-01

    Being invented more than fifty years ago, the ultrasonic pulse-echo technique has proven itself as a valuable and indispensable non-destructive tool to explore elastic properties of materials in engineering and scientific tasks. We propose a new design for the instrument based on mass-produced integral microchips. In our design the radiofrequency echo-pulse signal is processed by AD8302 RF gain and phase detector (www.analog.com).Its phase output is linearly proportional to the phase difference between the exciting and response signals. The gain output is proportional to the log of the ratio of amplitudes of the received to the exciting signals. To exclude the non-linear fragments and to enable exploring large phase changes, we employ parallel connection of two detectors, fed by in-phase and quadrature signals respectively. The instrument allowed us exploring phase transitions with precision of ΔV / V ~10-7 (V is the ultrasound speed). The high sensitivity of the logarithmic amplifiers embedded into AD8302 requires good grounding and screening of the receiving circuitry.

  8. High Sensitivity, High Frequency and High Time Resolution Decimetric Spectroscope

    Science.gov (United States)

    Sawant, H. S.; Rosa, R. R.

    1990-11-01

    RESUMEN. Se ha desarrollado el primer espectroscopio decimetrico latino americano operando en una banda de 100 MHz con alta resoluci6n de fre- cuencia (100 KHz) y tiempo (10 ms), alrededor de cualquier centro de frecuencia en el intervalo de 2000-200 MHz. El prop6sito de esta nota es describir investigaciones solares y no solares que se planean, progra ma de investigaci6n y la situaci6n actual de desarrollo de este espectroscopio. ABSTRACT. First Latin American Decimetric Spectroscope operating over a band of 100 MHz with high resolution in frequency (100 KHz) and time (10 ms), around any center frequency in the range of 2000-200 MHz is being developed. The purpose of this note is to describe planned solar, and non-solar, research programmes and present status of development of this spectroscope. Keq wo : INSTRUMENTS - SPECTROSCOPY

  9. Development of a highly sensitive galvanic cell oxygen sensor.

    Science.gov (United States)

    Ogino, H; Asakura, K

    1995-02-01

    A highly sensitive galvanic cell oxygen sensor was successfully developed for determining parts per billion of oxygen in high purity gases such as nitrogen, argon, etc. The response of this improved sensor was proportional in the range of oxygen concentrations from 10.0 ppm to the detection limit. The response speed in this study was improved to within 90 sec for a 90% response. The detection limit was tentatively found to be less than 0.4 ppb corresponding to S N = 2 .

  10. Determination of Vagal Baroreflex sensitivity in Normal Subjects

    Science.gov (United States)

    Wada, Naoki; Singer, Wolfgang; Gehrking, Tonette L.; Sletten, David M.; Schmelzer, James D.; Kihara, Mikihiro; Low, Phillip A.

    2014-01-01

    Introduction The Valsalva maneuver (VM) is used widely to quantify the sensitivity of the vagal baroreflex loop (vagal baroreflex sensitivity, BRS_v), but most studies have focused on the heart rate (HR) response to blood pressure (BP) decrement (BRS_v↓), even though the subsequent response to an increment in BP following the VM (BRS_v↑) is important and different. Methods We evaluated recordings of HR and BP in 187 normal subjects during the VM and determined both BRS_v↑ determined by relating HR to the BP increase following phase III and BRS_v↓. Results BRS_v↑ was related inversely to age. In addition, BRS_v↓, age, and magnitude of phase IV were independent predictors of BRS_v↑ in a multivariate model, accounting for 47% of the variance of BRS_v↑. Discussion The results indicate that both BRS_v↑ and BRS_v↓ become blunted with increasing age and that these indices relate to each other. PMID:24477673

  11. Financial Literacy of Youth. A Sensitivity Analysis of the Determinants

    Directory of Open Access Journals (Sweden)

    Nagar A. Κ.

    2008-04-01

    Full Text Available This paper reports on the potential use of Neural Network as a sensitivity modeling tool for the determinants of financial literacy. The financial literacy modeling in this research has been attempted to measure the literacy of youth in the Australian society with respect to their financial knowledge of Credit Cards, Loans and Superannuation (Pensions scheme in Australia that allows for choice of funds and investment decisions by the member. Based on the financial literacy related parameters, Neural Networks results showed good promise and capability for efficient financial literacy determinants, and represent a potentially robust and fault tolerant approach. The findings indicate that the determinants of credit card are significantly dependent on a student’s year of study, credit card status and daily routine, which has a strong relevance to respondents’ knowledge of credit cards. (n=1070; 9.0070 and 10.5898 respectively. This study did not have the intention to explore the skills of youth in order to measure the level of financial literacy but the objective was to test the basic financial knowledge of key products that is common to youth in Australian society. In so doing, the researchers were keen to identify the determinants of financial knowledge.

  12. MICROORGANISMS ANTIBIOTIC SENSITIVITY DETERMINATION IN URINARY TRACT INFECTIONS

    Directory of Open Access Journals (Sweden)

    Shapovalova O.V.

    2016-06-01

    Full Text Available Introduction. Nowadays Urinary tract infections (UTI are considered to be the most common bacterial infections. Escherichia coli is the most frequently uropathogen. Other microorganisms of the genera Enterococcus, Klebsiella, Enterobacter, Proteus, Morganella, Citrobacter, Serratia, Pseudomonas, Streptococcus, Staphylococcus, Candida are also isolated with variable frequency. In recent years there has been a decreasing tendency of the causative agents of UTI sensitivity to various antibiotics, which causes growth of an inefficiency treatment risk. In connection with the above the investigations were carried out with the purpose to identify the actual causative agents of bacteriuria and their sensitivity to antibiotics and antifungal drugs. Materials and methods. Bacteriological examination of urine was performed at 42 patients of SI "Sytenko Institute of Spine and Joint Pathology, AMS of Ukraine" clinic. The bacteriological method for determining the number of bacteria in the test material, cultural and bacterioscopic methods for identifying microorganisms and disk-diffusion method for sensitivity of microorganisms to antibiotics determining were used. The clinical material for the study was an average portion of the morning urine or urine collected by catheter. The biological material collection and bacteriological examination was carried by quantitative method, the isolated microorganisms identification and their sensitivity to antibiotics determining was performed by standard methods in accordance with current guidelines. We used the following antibiotics group to determine the microorganisms sensitivity: penicillin, cephalosporin, karbapenems, tetracyclines, aminoglycoside, fluoroquinolones, oxazolidinones, macrolides, lincosamides, glycopeptides, antifungal antibiotics. Results and discussion. During the biological material study 55 isolates of bacterial and fungal pathogens were obtained. The microorganisms’ concentration in urine was in

  13. Analysis of Cyberbullying Sensitivity Levels of High School Students and Their Perceived Social Support Levels

    Science.gov (United States)

    Akturk, Ahmet Oguz

    2015-01-01

    Purpose: The purpose of this paper is to determine the cyberbullying sensitivity levels of high school students and their perceived social supports levels, and analyze the variables that predict cyberbullying sensitivity. In addition, whether cyberbullying sensitivity levels and social support levels differed according to gender was also…

  14. Analysis of Cyberbullying Sensitivity Levels of High School Students and Their Perceived Social Support Levels

    Science.gov (United States)

    Akturk, Ahmet Oguz

    2015-01-01

    Purpose: The purpose of this paper is to determine the cyberbullying sensitivity levels of high school students and their perceived social supports levels, and analyze the variables that predict cyberbullying sensitivity. In addition, whether cyberbullying sensitivity levels and social support levels differed according to gender was also…

  15. Carbon dots based fluorescent sensor for sensitive determination of hydroquinone.

    Science.gov (United States)

    Ni, Pengjuan; Dai, Haichao; Li, Zhen; Sun, Yujing; Hu, Jingting; Jiang, Shu; Wang, Yilin; Li, Zhuang

    2015-11-01

    In this paper, a novel biosensor based on Carbon dots (C-dots) for sensitive detection of hydroquinone (H2Q) is reported. It is interesting to find that the fluorescence of the C-dots could be quenched by H2Q directly. The possible quenching mechanism is proposed, which shows that the quenching effect may be caused by the electron transfer from C-dots to oxidized H2Q-quinone. Based on the above principle, a novel C-dots based fluorescent probe has been successfully applied to detect H2Q. Under the optimal condition, detection limit down to 0.1 μM is obtained, which is far below U.S. Environmental Protection Agency estimated wastewater discharge limit of 0.5 mg/L. Moreover, the proposed method shows high selectivity for H2Q over a number of potential interfering species. Finally, several water samples spiked with H2Q are analyzed utilizing the sensing method with satisfactory recovery. The proposed method is simple with high sensitivity and excellent selectivity, which provides a new approach for the detection of various analytes that can be transformed into quinone.

  16. Genetic determinants of sensitivity to beryllium in mice.

    Science.gov (United States)

    Tarantino-Hutchison, Lauren M; Sorrentino, Claudio; Nadas, Arthur; Zhu, Yiwen; Rubin, Edward M; Tinkle, Sally S; Weston, Ainsley; Gordon, Terry

    2009-06-01

    Chronic beryllium disease (CBD), an irreversible, debilitating granulomatous lung disease is caused by exposure to beryllium. This occupational hazard occurs in primary production and machining of Be-metal, BeO, beryllium - containing alloys, and other beryllium products. CBD begins as an MHC Class II-restricted, T(H)1 hypersensitivity, and the Human Leukocyte Antigen, HLA-DPB1E(69), is associated with risk of developing CBD. Because inbred strains of mice have not provided good models of CBD to date, three strains of HLA-DPB1 transgenic mice in an FVB/N background were developed; each contains a single allele of HLA-DPB1 that confers a different magnitude of risk for chronic beryllium disease: HLA-DPB1*0401 (OR approximately 0.2), HLA-DPB1*0201 (OR approximately 3), and HLA-DPB1*1701 (OR approximately 46). The mouse ear swelling test (MEST) was employed to determine if these different alleles would support a hypersensitivity response to beryllium. Mice were first sensitized on the back and subsequently challenged on the ear. In separate experiments, mice were placed into one of three groups (sensitization/challenge): C/C, C/Be, and Be/Be. In the HLA-DPB1*1701 mice, the strain with the highest risk transgene, the Be/Be group was the only group that displayed significant maximum increased ear thickness of 19.6% +/- 3.0% over the baseline measurement (p beryllium in seven inbred strains were investigated through use of the MEST, these included: FVB/N, AKR, Balb/c, C3H/HeJ, C57/BL6, DBA/2, and SJL/J. The FVB/N strain was least responsive, while the SJL/J and C57/BL6 strains were the highest responders. Our results suggest that the HLA-DPB1*1701 transgene product is an important risk factor for induction of the beryllium-sensitive phenotype. This model should be a useful tool for investigating beryllium sensitization.

  17. Sensitive determination of the Young's modulus of thin films by polymeric microcantilevers

    DEFF Research Database (Denmark)

    Colombi, Paolo; Bergese, Paolo; Bontempi, Elza;

    2013-01-01

    A method for the highly sensitive determination of the Young's modulus of TiO2 thin films exploiting the resonant frequency shift of a SU-8 polymer microcantilever (MC) is presented. Amorphous TiO2 films with different thickness ranging from 10 to 125 nm were grown at low temperature (90 °C) with...

  18. A highly sensitive method for quantification of iohexol

    DEFF Research Database (Denmark)

    Schulz, A.; Boeringer, F.; Swifka, J.

    2014-01-01

    lohexol (1-N,3-N-bis(2,3-dihydroxypropyl)-5-IN-(2,3-dihydroxypropyl) acetamide-2,4,6-triiodobenzene1,3-dicarboxamide) is used for accurate determination of the glomerular filtration rate (GFR) in chronic kidney disease (CKD) patients. However, high iohexol amounts might lead to adverse effects in...... in organisms. In order to minimize the iohexol dosage required for the GFR determination in humans, the development of a sensitive quantification method is essential. Therefore, the objective of our preclinical study was to establish and validate a simple and robust liquid...... with a cut-off of 3 kDa. The chromatographic separation was achieved on an analytical Zorbax SB C18 column. The detection and quantification were performed on a high capacity trap mass spectrometer using positive ion ESI in the multiple reaction monitoring (MRM) mode. Furthermore, using real-time polymerase...

  19. Influence of Smoking on Ultra-High-Frequency Auditory Sensitivity.

    Science.gov (United States)

    Prabhu, Prashanth; Varma, Gowtham; Dutta, Kristi Kaveri; Kumar, Prajwal; Goyal, Swati

    2017-04-01

    In this study, an attempt was made to determine the effect of smoking on ultra-high-frequency auditory sensitivity. The study also attempted to determine the relationship between the nature of smoking and ultra-high-frequency otoacoustic emissions (OAEs) and thresholds. The study sample included 25 smokers and 25 non-smokers. A detailed history regarding their smoking habits was collected. High-frequency audiometric thresholds and amplitudes of high-frequency distortion-product OAEs were analyzed for both ears from all participants. The results showed that the ultra-high-frequency thresholds were elevated and that there was reduction in the amplitudes of ultra-high-frequency OAEs in smokers. There was an increased risk of auditory damage with chronic smoking. The study results highlight the application of ultra-high-frequency OAEs and ultra-high-frequency audiometry for the early detection of auditory impairment. However, similar studies should be conducted on a larger population for better generalization of the results.

  20. [A simple highly sensitive recording microspectrophotometer].

    Science.gov (United States)

    Govardovskiĭ, V I; Zueva, L V

    1988-04-01

    A design of the recording microspectrophotometer is described. The instrument possesses an absolutely flat base line and quantum-noise limited detection threshold. Two principal elements of the design are the "jumping" stage, and the logarithmic amplifier with the phase-sensitive detector which converts the photomultiplier output into the optical density signal. The performance of the instrument is illustrated by the recordings of visual pigment spectra in single photoreceptors.

  1. A simplified screening procedure for determination of total N-NO groups (TNG) and nitrite (NO2-) in commercial low-molecular-weight heparins (LMWH) by selective chemical denitrosation followed by high-sensitivity chemiluminescence detection (NO-analyzer, NOA).

    Science.gov (United States)

    Beretta, Giangiacomo; Gelmini, Fabrizio; Merlino, Mario; Furlanetto, Sandra; Facino, Roberto Maffei

    2009-07-12

    Aim of this work was to set up a method for the sensitive and selective determination of nitrite (NO(2)(-)) and total N-nitroso groups (TNG) in dalteparin and nadroparin, commercial low- molecular-weight heparins (LMWH), prepared by deaminative depolymerization of heparin with nitrous acid. The European Pharmacopoeia VI ed. indicates respectively 5 ppm as the maximum content for contaminant NO(2)(-) in the former and 0.25 ppm for TNG in the latter and no clear indication is given for N-NO groups in dalteparin, i.e. TNG must be absent because of the specific manufacturing process. The proposed technique is based on the development of a pre-analytical device, coupled to a chemiluminometer, constituted by three sequentially connected and commercially available purge vessels, where selective reagents are employed for the conversion of NO(2)(-) and N-NO to nitric oxide (NO). In detail, NO(2)(-) was determined in the first chamber and non-volatile and volatile TNG in the second and third. This method was validated for selectivity, sensitivity, linearity, accuracy and precision. The method was shown to be selective, with a quantitative linear range of 1-1000 ppb). The bias, intra- and inter-day percent relative error was lower than 1%. The contamination of NO(2)(-) and TNG in nadreparin was below the limits; for dalteparin NO(2)(-) fell within the limit, but there was a huge amount of TNG (15.80+/-0.05 ppm-6.69+/-0.02 ppm). Preliminary investigation on the solvent-extractable material from dalteparin showed the majority of chemiluminescence retained in the aqueous residue to indicate that this N-NO groups may belong to solvent unextractable material or be tightly bound to the dalteparin backbone.

  2. Neighborhood properties are important determinants of temperature sensitive mutations.

    Directory of Open Access Journals (Sweden)

    Svetlana Lockwood

    Full Text Available Temperature-sensitive (TS mutants are powerful tools to study gene function in vivo. These mutants exhibit wild-type activity at permissive temperatures and reduced activity at restrictive temperatures. Although random mutagenesis can be used to generate TS mutants, the procedure is laborious and unfeasible in multicellular organisms. Further, the underlying molecular mechanisms of the TS phenotype are poorly understood. To elucidate TS mechanisms, we used a machine learning method-logistic regression-to investigate a large number of sequence and structure features. We developed and tested 133 features, describing properties of either the mutation site or the mutation site neighborhood. We defined three types of neighborhood using sequence distance, Euclidean distance, and topological distance. We discovered that neighborhood features outperformed mutation site features in predicting TS mutations. The most predictive features suggest that TS mutations tend to occur at buried and rigid residues, and are located at conserved protein domains. The environment of a buried residue often determines the overall structural stability of a protein, thus may lead to reversible activity change upon temperature switch. We developed TS prediction models based on logistic regression and the Lasso regularized procedure. Through a ten-fold cross-validation, we obtained the area under the curve of 0.91 for the model using both sequence and structure features. Testing on independent datasets suggested that the model predicted TS mutations with a 50% precision. In summary, our study elucidated the molecular basis of TS mutants and suggested the importance of neighborhood properties in determining TS mutations. We further developed models to predict TS mutations derived from single amino acid substitutions. In this way, TS mutants can be efficiently obtained through experimentally introducing the predicted mutations.

  3. Sensitivity study of reliable, high-throughput resolution metricsfor photoresists

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Christopher N.; Naulleau, Patrick P.

    2007-07-30

    The resolution of chemically amplified resists is becoming an increasing concern, especially for lithography in the extreme ultraviolet (EUV) regime. Large-scale screening and performance-based down-selection is currently underway to identify resist platforms that can support shrinking feature sizes. Resist screening efforts, however, are hampered by the absence of reliable resolution metrics that can objectively quantify resist resolution in a high-throughput fashion. Here we examine two high-throughput metrics for resist resolution determination. After summarizing their details and justifying their utility, we characterize the sensitivity of both metrics to two of the main experimental uncertainties associated with lithographic exposure tools, namely: limited focus control and limited knowledge of optical aberrations. For an implementation at EUV wavelengths, we report aberration and focus limited error bars in extracted resolution of {approx} 1.25 nm RMS for both metrics making them attractive candidates for future screening and down-selection efforts.

  4. High-Sensitivity GaN Microchemical Sensors

    Science.gov (United States)

    Son, Kyung-ah; Yang, Baohua; Liao, Anna; Moon, Jeongsun; Prokopuk, Nicholas

    2009-01-01

    Systematic studies have been performed on the sensitivity of GaN HEMT (high electron mobility transistor) sensors using various gate electrode designs and operational parameters. The results here show that a higher sensitivity can be achieved with a larger W/L ratio (W = gate width, L = gate length) at a given D (D = source-drain distance), and multi-finger gate electrodes offer a higher sensitivity than a one-finger gate electrode. In terms of operating conditions, sensor sensitivity is strongly dependent on transconductance of the sensor. The highest sensitivity can be achieved at the gate voltage where the slope of the transconductance curve is the largest. This work provides critical information about how the gate electrode of a GaN HEMT, which has been identified as the most sensitive among GaN microsensors, needs to be designed, and what operation parameters should be used for high sensitivity detection.

  5. Use of radiation sources with mercury isotopes for real-time highly sensitive and selective benzene determination in air and natural gas by differential absorption spectrometry with the direct Zeeman effect

    Energy Technology Data Exchange (ETDEWEB)

    Revalde, Gita, E-mail: gitar@latnet.lv [Institute of Technical Physics, Riga Technical University, P.Valdena 3, Riga LV 1050 (Latvia); Sholupov, Sergey; Ganeev, Alexander; Pogarev, Sergey; Ryzhov, Vladimir [St. Petersburg State University, Universitetskaya nab., 7/9, St. Petersburg 199034 (Russian Federation); Skudra, Atis [Institute of Atomic Physics and Spectroscopy, University of Latvia, Skunu 4, Riga (Latvia)

    2015-08-05

    A new analytical portable system is proposed for the direct determination of benzene vapor in the ambient air and natural gas, using differential absorption spectrometry with the direct Zeeman effect and innovative radiation sources: capillary mercury lamps with different isotopic compositions ({sup 196}Hg, {sup 198}Hg, {sup 202}Hg, {sup 204}Hg, and natural isotopic mixture). Resonance emission of mercury at a wavelength of 254 nm is used as probing radiation. The differential cross section of benzene absorption in dependence on wavelength is determined by scanning of magnetic field. It is found that the sensitivity of benzene detection is enhanced three times using lamp with the mercury isotope {sup 204}Hg in comparison with lamp, filled with the natural isotopic mixture. It is experimentally demonstrated that, when benzene content is measured at the Occupational Exposure Limit (3.2 mg/m{sup 3} for benzene) level, the interference from SO{sub 2}, NO{sub 2}, O{sub 3}, H{sub 2}S and toluene can be neglected if concentration of these gases does not exceed corresponding Occupational Exposure Limits. To exclude the mercury effect, filters that absorb mercury and let benzene pass in the gas duct are proposed. Basing on the results of our study, a portable spectrometer is designed with a multipath cell of 960 cm total path length and detection limit 0.5 mg/m{sup 3} at 1 s averaging and 0.1 mg/m{sup 3} at 30 s averaging. The applications of the designed spectrometer to measuring the benzene concentration in the atmospheric air from a moving vehicle and in natural gas are exemplified. - Highlights: • Portable benzene analyser is designed for direct benzene detection in air and gas. • Zeeman effect absorption spectrometry ensures very low benzene detection limits. • The Hg 2537 nm emission line from capillary mercury lamp is used for absorption. • The best sensitivity and selectivity is found using Hg 204 isotope light source. • Mercury influence is

  6. Triggers for a high sensitivity charm experiment

    Energy Technology Data Exchange (ETDEWEB)

    Christian, D.C.

    1994-07-01

    Any future charm experiment clearly should implement an E{sub T} trigger and a {mu} trigger. In order to reach the 10{sup 8} reconstructed charm level for hadronic final states, a high quality vertex trigger will almost certainly also be necessary. The best hope for the development of an offline quality vertex trigger lies in further development of the ideas of data-driven processing pioneered by the Nevis/U. Mass. group.

  7. A simple and sensitive method for determination of Norfloxacin in pharmaceutical preparations

    Directory of Open Access Journals (Sweden)

    Zhuo Ye

    2015-06-01

    Full Text Available In this approach, a new voltammetric method for determination of norfloxacin was proposed with high sensitivity and wider detection linear range. The used voltammetric sensor was fabricated simply by coating a layer of graphene oxide (GO and Nafion composited film on glassy carbon electrode. The advantage of proposed method was sensitive electrochemical response for norfloxacin, which was attributed to the excellent electrical conductivity of GO and the accumulating function of Nafion under optimum experimental conditions, the present method revealed a good linear response for determination of norfloxacin in the range of 1×10-8mol/L-7×10-6 mol/L with a detection limit of 5×10-9 mol/L. The proposed method was successfully applied in the determination of norfloxacin in capsules with satisfactory results.

  8. Scalloped electrodes for highly sensitive electrical measurements

    DEFF Research Database (Denmark)

    Vazquez Rodriguez, Patricia; Dimaki, Maria; Svendsen, Winnie Edith

    2011-01-01

    In this work we introduce a novel out-of-plane electrode with pronounced scalloped surface and high aspect ratio for electrical recordings of brain tissue in vitro, with the aim to reduce significantly the impedance of the measuring system. The profile and height of the structures is tailored...... by means of silicon fabrication techniques that sharpen them progressively and in a controlled manner. We will show that the use of the scalloped area achieves a great decrease in impedance, which is very significant for a reduction of noise in electrical measurements. The measured impedance reflects...

  9. Determination of a lower bound on Earth's climate sensitivity

    Directory of Open Access Journals (Sweden)

    STEPHEN E. Schwartz

    2013-09-01

    Full Text Available Transient and equilibrium sensitivity of Earth's climate has been calculated using global temperature, forcing and heating rate data for the period 1970–2010. We have assumed increased long-wave radiative forcing in the period due to the increase of the long-lived greenhouse gases. By assuming the change in aerosol forcing in the period to be zero, we calculate what we consider to be lower bounds to these sensitivities, as the magnitude of the negative aerosol forcing is unlikely to have diminished in this period. The radiation imbalance necessary to calculate equilibrium sensitivity is estimated from the rate of ocean heat accumulation as 0.37±0.03 W m−2 (all uncertainty estimates are 1−σ. With these data, we obtain best estimates for transient climate sensitivity 0.39±0.07 K (W m−2−1 and equilibrium climate sensitivity 0.54±0.14 K (W m−2−1, equivalent to 1.5±0.3 and 2.0±0.5 K (3.7 W m−2−1, respectively. The latter quantity is equal to the lower bound of the ‘likely’ range for this quantity given by the 2007 IPCC Assessment Report. The uncertainty attached to the lower-bound equilibrium sensitivity permits us to state, within the assumptions of this analysis, that the equilibrium sensitivity is greater than 0.31 K (W m−2−1, equivalent to 1.16 K (3.7 W m−2−1, at the 95% confidence level.

  10. Sensitive chiral high-performance liquid chromatographic determination of anthelmintic flubendazole and its phase I metabolites in blood plasma using UV photodiode-array and fluorescence detection Application to pharmacokinetic studies in sheep.

    Science.gov (United States)

    Nobilis, Milan; Vybíralová, Zuzana; Krízová, Veronika; Kubícek, Vladimír; Soukupová, Marie; Lamka, Jirí; Szotáková, Barbora; Skálová, Lenka

    2008-12-01

    Although benzimidazole anthelmintic flubendazole, methyl ester of [5-(4-fluorobenzoyl)-1H-benzimidazol-2-yl]carbamic acid, is extensively used in veterinary and human medicine for the treatment of gastrointestinal parasitic helminth infections, reliable data about its pharmacokinetics in various species have not been reported. Our previous work [M. Nobilis, Th. Jira, M. Lísa, M. Holcapek, B. Szotáková, J. Lamka, L.Skálová, J. Chromatogr. A 1149 (2007) 112-120] had described the stereospecificity of carbonyl reduction during phase I metabolic experiments in vitro. For in vivo pharmacokinetic studies, further improvement and optimization of bioanalytical HPLC method in terms of sensitivity and selectivity was necessary. Hence, a modified chiral bioanalytical HPLC method involving both UV photodiode-array and fluorescence detection for the determination of flubendazole, both enantiomers of reduced flubendazole and hydrolyzed flubendazole in the extracts from plasma samples was tested and validated. Albendazole was used as an internal standard. Sample preparation process involved a pH-dependent extraction of the analytes from the blood plasma into tert-butylmethyl ether. Chromatographic separations were performed on a Chiralcel OD-R 250 mm x 4.6mm column with mobile phase methanol-1M NaClO(4) (75:25, v/v) at the flow rate 0.5 ml min(-1). In quantitation, selective UV absorption maxima of 290 nm (for reduced flubendazole), 295 nm (for albendazole), 310 nm (for flubendazole) and 330 nm (for hydrolyzed flubendazole) were used in the UV photodiode-array detection, and lambda(exc.)/lambda(emis.)=228 nm/310 nm (for reduced flubendazole) and lambda(exc.)/lambda(emis.)=236 nm/346 nm (for albendazole) were set on the fluorescence detector. The fluorescence detection was approximately 10-times more sensitive than the UV detection. Each HPLC run lasted 27 min. The validated chiral HPLC-PDA-FL method was employed in the pharmacokinetic studies of flubendazole in sheep. The

  11. Multipurpose High Sensitivity Radiation Detector: Terradex

    Energy Technology Data Exchange (ETDEWEB)

    Alpat, Behcet [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy)]. E-mail: behcet.alpat@pg.infn.it; Aisa, Damiano [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Bizzarri, Marco [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Blasko, Sandor [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Esposito, Gennaro [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Farnesini, Lucio [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Fiori, Emmanuel [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Papi, Andrea [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Postolache, Vasile [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Renzi, Francesca [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Ionica, Romeo [Politecnica University of Bucarest, Splaiul Indipendentei, Bucharest (Romania); Manolescu, Florentina [Space Science Institute of Bucharest, Maugurele, Bucharest (Romania); Ozkorucuklu, Suat [Suleyman Demirel Universitesi, Isparta (Turkey); Denizli, Haluk [Abant Izzet Baysal Universitesi, Bolu (Turkey); Tapan, Ilhan [Uludag Universitesi, Bursa (Turkey); Ercan Pilicer [Uludag Universitesi, Bursa (Turkey); Egidi, Felice [SITE Technology, Carsoli (Italy); Moretti, Cesare [SITE Technology, Carsoli(AQ) (Italy); Dicola, Luca [SITE Technology, Carsoli(AQ) (Italy)

    2007-05-11

    Terradex project aims to realise an accurate and programmable multiparametric tool which will measure relevant physical quantities such as observation time, energy and type of all decay products of three naturally occurring decay chains of uranium and thorium series present in nature as well as the decay products of man-made radioactivity. The measurements described in this work are based on the performance tests of the first version of an instrument that is designed to provide high counting accuracy, by introducing self-triggering, delayed time-coincidence technique, of products of a given decay chain. In order to qualify the technique and to calibrate the Terradex, a {sup 222}Rn source is used. The continuous and accurate monitoring of radon concentration in air is realised by observing the alpha and beta particles produced by the decay of {sup 222}Rn and its daughters and tag each of them with a precise occurrence time. The validity of delayed coincident technique by using the state of the art electronics with application of novel data sampling and analysis methods are discussed. The flexibility of sampling protocols and the advantages of online calibration capability to achieve the highest level of precision in natural and man-made radiation measurements are also described.

  12. Tunable diameter electrostatically formed nanowire for high sensitivity gas sensing

    Institute of Scientific and Technical Information of China (English)

    Alex Henning; Nandhini Swaminathan; Andrey Godkin; Gil Shalev; Iddo Amit; Yossi Rosenwaks

    2015-01-01

    We report on an electrostatically formed nanowire (EFN)-based sensor with tunable diameters in the range of 16 nm to 46 nm and demonstrate an EFN- based field-effect transistor as a highly sensitive and robust room temperature gas sensor. The device was carefully designed and fabricated using standard integrated processing to achieve the 16 nm EFN that can be used for sensing without any need for surface modification. The effective diameter for the EFN was determined using Kelvin probe force microscopy accompanied by three- dimensional electrostatic simulations. We show that the EFN transistor is capable of detecting 100 parts per million of ethanol gas with bare SiO2.

  13. Some problems connected with boron determination by atomic absorption spectroscopy and the sensitivity improvement

    Directory of Open Access Journals (Sweden)

    JELENA J. SAVOVIC

    2001-08-01

    Full Text Available Two atomizers were compared: an N2O–C2H2 flame and a stabilized U-shaped DC arc with aerosol supply. Both the high plasma temperature and the reducing atmosphere obtained by acetylene addition to the argon stream substantially increase the sensitivity of boron determination by atomic absorption spectroscopy (AAS when the arc atomizer is used. The results were compared with those for silicon as a control element. The experimental characteristic concentrations for both elements were compared with the computed values. The experimentally obtained characteristic concentration for boron when using the arc atomizer was in better agreement with the calculated value. It was estimated that the influence of stable monoxide formation on the sensitivity for both elements was about the same, but reduction of analyte and formation of non-volatile carbide particles was more important for boron, which is the main reason for the low sensitivity of boron determination using a flame atomizer. The use of an arc atomizer suppresses this interference and significantly improves the sensitivity of the determination.

  14. SENSE shimming (SSH): A fast approach for determining B(0) field inhomogeneities using sensitivity coding.

    Science.gov (United States)

    Splitthoff, D N; Zaitsev, M

    2009-11-01

    The pursuit of ever higher field strengths and faster data acquisitions has led to the construction of coil arrays with high numbers of elements. With the sensitivity encoding (SENSE) technique, it has been shown that the sensitivity of those elements can be used for spatial image encoding. Here, a proof-of-principle is presented of a method that can be considered an extreme case of the SENSE approach, completely abstaining from using encoding gradients. The resulting sensitivity encoded free-induction decay (FID) data are then not used for imaging, but for determining B(0) field inhomogeneity distribution. The method has therefore been termed "SENSE shimming" (SSH). In phantom experiments the method's ability to detect inhomogeneities of up to the second order is demonstrated.

  15. How to Determine the Increasing Returns Sensitivity of Your Industry?

    NARCIS (Netherlands)

    M.H. Klein (Martin); E. den Hartigh; H.R. Commandeur (Harry); F. Langerak (Fred)

    2004-01-01

    textabstractIncreasing returns means that self-reinforcing mechanisms are at work within firms and markets. These mechanisms come in four forms: scale effects, learning effects, network effects and social interaction effects. Some industries are more sensitive to increasing returns than others. It i

  16. A highly sensitive fiber Bragg grating diaphragm pressure transducer

    Science.gov (United States)

    Allwood, Gary; Wild, Graham; Lubansky, Alex; Hinckley, Steven

    2015-10-01

    In this work, a novel diaphragm based pressure transducer with high sensitivity is described, including the physical design structure, in-depth analysis of optical response to changes in pressure, and a discussion of practical implementation and limitations. A flat circular rubber membrane bonded to a cylinder forms the body of the transducer. A fiber Bragg grating bonded to the center of the diaphragm structure enables the fractional change in pressure to be determined by analyzing the change in Bragg wavelength of the reflected spectra. Extensive evaluation of the physical properties and optical characteristics of the transducer has been performed through experimentation, and modeling using small deformation theory. The results show the transducer has a sensitivity of 0.116 nm/kPa, across a range of 15 kPa. Ultra-low cost interrogation of the optical signal was achieved through the use of an optically mismatched Bragg grating acting as an edge filter to convert the spectral change into an intensity change. A numerical model of the intensity based interrogation was implemented in order to validate the experimental results. Utilizing this interrogation technique and housing both the sensing and reference Bragg gratings within the main body of the transducer means it is effectively temperature insensitive and easily connected to electronic systems.

  17. Sensitivity of once-shocked, weathered high explosives

    Energy Technology Data Exchange (ETDEWEB)

    Williams, K.L.; Harris, B.W.

    1998-07-01

    Effects caused by stimulating once-shocked, weathered high explosives (OSW-HE) are investigated. The sensitivity of OSW-HE to mechanical stimuli was determined using standard industry tests. Some initial results are given. Pieces of OSW-HE were collected from active and inactive firing sites and from an area surrounding a drop tower at Los Alamos where skid and spigot tests were done. Samples evaluated were cast explosives or plastic bonded explosive (PBX) formulations containing cyclotrimethylenetrinitramine (RDX), cyclotetramethylene tetranitramine (HMX), 2,4,6-trinitrotoluene (TNT), mock or inert HE [tris(beta-chloroethyl)phosphate (CEF)], barium nitrate, cyanuric acid, talc, and Kel-F. Once-shocked, weathered LX-10 Livermore explosive [HMX/Viton A, (95/5 wt %)], PBX 9011 [HMX/Estane, (90/10 wt %)], PBX 9404 [HMX/nitrocellulose, tris(beta-chloroethyl) phosphate, (94/3/3 wt %)], Composition B or cyclotol (TNT/RDX explosives), and PBX 9007 (90% RDX, 9.1% styrene, 0.5% dioctyl phthalate, and 0.45 resin) were subjected to the hammer test, the drop-weight impact sensitivity test, differential thermal analysis (DTA), the spark test, the Henkin`s critical temperature test, and the flame test. Samples were subjected to remote, wet cutting and drilling; remote, liquid-nitrogen-cooled grinding and crushing; and scanning electron microscope (SEM) surface analyses for morphological changes.

  18. Sensitized effect of β-cyclodextrin on the fluorescence in the determination of carbaryl

    Institute of Scientific and Technical Information of China (English)

    LIU Wen-li; TANG Bo

    2004-01-01

    Based on the significant enhancement of fluorescence intensity of carbaryl in inclusion complex, a spetrofluorimetric method with high sensitivity was developed for the determination of carbaryl in aqueous solution. Under the optimum conditions, the complex had excitation and emission maxima at 278 nm and 332 nm, respectively. The linear range of the method was 7.0 ng/ml-1500 ng/ml with a detection limit of 1.2 ng/ml. The proposed method was successfully used to determine quantitatively of carbaryl in cottonseeds.

  19. Design optimization of high pressure and high temperature piezoresistive pressure sensor for high sensitivity

    Science.gov (United States)

    Niu, Zhe; Zhao, Yulong; Tian, Bian

    2014-01-01

    This paper describes a design method for optimizing sensitivity of piezoresistive pressure sensor in high-pressure and high-temperature environment. In order to prove the method, a piezoresistive pressure sensor (HPTSS) is designed. With the purpose of increasing sensitivity and to improve the measurement range, the piezoresistive sensor adopts rectangular membrane and thick film structure. The configuration of piezoresistors is arranged according to the characteristic of the rectangular membrane. The structure and configuration of the sensor chip are analyzed theoretically and simulated by the finite element method. This design enables the sensor chip to operate in high pressure condition (such as 150 MPa) with a high sensitivity and accuracy. The silicon on insulator wafer is selected to guarantee the thermo stability of the sensor chip. In order to optimize the fabrication and improve the yield of production, an electric conduction step is devised. Series of experiments demonstrates a favorable linearity of 0.13% and a high accuracy of 0.48%. And the sensitivity of HTPSS is about six times as high as a conventional square-membrane sensor chip in the experiment. Compared with the square-membrane pressure sensor and current production, the strength of HPTTS lies in sensitivity and measurement. The performance of the HPTSS indicates that it could be an ideal candidate for high-pressure and high-temperature sensing in real application.

  20. Design optimization of high pressure and high temperature piezoresistive pressure sensor for high sensitivity.

    Science.gov (United States)

    Niu, Zhe; Zhao, Yulong; Tian, Bian

    2014-01-01

    This paper describes a design method for optimizing sensitivity of piezoresistive pressure sensor in high-pressure and high-temperature environment. In order to prove the method, a piezoresistive pressure sensor (HPTSS) is designed. With the purpose of increasing sensitivity and to improve the measurement range, the piezoresistive sensor adopts rectangular membrane and thick film structure. The configuration of piezoresistors is arranged according to the characteristic of the rectangular membrane. The structure and configuration of the sensor chip are analyzed theoretically and simulated by the finite element method. This design enables the sensor chip to operate in high pressure condition (such as 150 MPa) with a high sensitivity and accuracy. The silicon on insulator wafer is selected to guarantee the thermo stability of the sensor chip. In order to optimize the fabrication and improve the yield of production, an electric conduction step is devised. Series of experiments demonstrates a favorable linearity of 0.13% and a high accuracy of 0.48%. And the sensitivity of HTPSS is about six times as high as a conventional square-membrane sensor chip in the experiment. Compared with the square-membrane pressure sensor and current production, the strength of HPTTS lies in sensitivity and measurement. The performance of the HPTSS indicates that it could be an ideal candidate for high-pressure and high-temperature sensing in real application.

  1. A highly sensitive colorimetric and ratiometric sensor for fluoride ion

    Institute of Scientific and Technical Information of China (English)

    Zhao Wu Xu; Jin Tang; He Tian

    2008-01-01

    A new benzoimidazole-naphthalimide derivative 4 was synthesized and its photophysical properties were studied.This compound showed highly selectively and sensitive colorimetric and ratiometric sensing ability for fluoride anion.

  2. Highly sensitive determination of doxycycline hydrochloride by molecularly imprinted sensor based on gate-controlled effect%应用门效应-分子印迹传感器测定盐酸强力霉素

    Institute of Scientific and Technical Information of China (English)

    魏小平; 吴芳; 李建平

    2013-01-01

    利用邻苯二胺作为功能单体,盐酸强力霉素为模板分子,用电聚合的方法在金电极表面制备出对盐酸强力霉素可进行特异识别的分子印迹膜,利用门控制原理对盐酸强力霉素进行测定.表征了分子印迹膜的性能、印迹效应;试验了测定条件;该传感器对盐酸强力霉素的检测具有良好的选择性.盐酸强力霉素的浓度在2.0×10-9~1.0 × 10-7mol/L范围内与响应电流呈线性关系,检出限达8.7×10-10 mol/L,低于现有分析方法.该传感器可用于鱼肉样品中盐酸强力霉素的检测,回收率在96.6% ~ 103.1%.%A sensitive molecularly imprinted electrochemical sensor of doxycycline hydrochloride based on gatecontrolled effect was prepared on the surface of gold electrode by electro polymerization with o-phenylenediamine as a functional monomers and doxycycline hydrochloride as a template molecule.The performance of molecular imprinted membrane and the imprinted effects were investigated,and the detection conditions were tested.The sensor exhibited good selectivity to doxycycline hydrochloride.A linear relationship between the current and the doxycycline hydrochloride concentration was found in the range of 2.0 × 10-9 ~ 1.0 × 10-7 mol/L,and the determination limit was 8.7 × 10-10 mol/L which is lower than that of most present methods.It has been applied to assay of real fish samples,and the recoveries of doxycycline hydrochloride from the samples ranged from 96.6% to 103.1%.

  3. Determining confounding sensitivities in eddy current thin film measurements

    Science.gov (United States)

    Gros, Ethan; Udpa, Lalita; Smith, James A.; Wachs, Katelyn

    2017-02-01

    Eddy current (EC) techniques are widely used in industry to measure the thickness of non-conductive films on a metal substrate. This is done by using a system whereby a coil carrying a high-frequency alternating current is used to create an alternating magnetic field at the surface of the instrument's probe. When the probe is brought near a conductive surface, the alternating magnetic field will induce ECs in the conductor. The substrate characteristics and the distance of the probe from the substrate (the coating thickness) affect the magnitude of the ECs. The induced currents load the probe coil affecting the terminal impedance of the coil. The measured probe impedance is related to the lift off between coil and conductor as well as conductivity of the test sample. For a known conductivity sample, the probe impedance can be converted into an equivalent film thickness value. The EC measurement can be confounded by a number of measurement parameters. It was the goal of this research to determine which physical properties of the measurement set-up and sample can adversely affect the thickness measurement. The eddy-current testing was performed using a commercially available, hand-held eddy-current probe (ETA3.3H spring-loaded eddy probe running at 8 MHz) that comes with a stand to hold the probe. The stand holds the probe and adjusts the probe on the z-axis to help position the probe in the correct area as well as make precise measurements. The signal from the probe was sent to a hand-held readout, where the results are recorded directly in terms of liftoff or film thickness. Understanding the effect of certain factors on the measurements of film thickness, will help to evaluate how accurate the ETA3.3H spring-loaded eddy probe was at measuring film thickness under varying experimental conditions. This research studied the effects of a number of factors such as i) conductivity, ii) edge effect, iii) surface finish of base material and iv) cable condition.

  4. A Sensitive Derivatization Method for the Determination of the Sugar Composition after Pre-column Reductive Amination with 3-Amino-9-ethylcarbazole (AEC) by High-Performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    ZHANG, Ying; HUANG, Lin-Juan; WANG, Zhong-Fu

    2007-01-01

    3-Amino-9-ethylcarbazole (AEC) was employed for monosaccharide derivatization. The derivatives can be analyzed by high-performance liquid chromatography (HPLC) with an ultraviolet detection (wavelength: 254 nm).Monosaccharides were quantitatively derivatized with 3-amino-9-ethylcarbazole (AEC) at 70 ℃ for 60 min. The method was linear for all samples over the concentration range tested (r>0.999), the precision was found to be satisfactory (R.S.D.<3%), and the recovery ratios were >98.62%. The stability analysis showed R.S.D. Was between 1.81%-3.16%. Detection limits for the samples (D-glucose, L-xylose, D-mannose, L-arabinose, and L-rhamnose)ranged from 0.06 to 1.97 ng/mL (S/N=3). Under the optimized derivatization and HPLC conditions, five monosaccharides were well separated using a narrow bore C18 column (250 mm× 4.6 mm) with 0.1 mol/L ammonium acetate containing 25% acetonitrile at a flow rate of 0.5 mL/min. As an application, the method has been successfully applied to the determination of monosaccharide compositions of three polysaccharides SPPA-1, SPPB-1 and SPPC- 1 of Spirulina platensis. This method also has potential application to oligosaccharide or glycan analyses.

  5. Transplantation in highly HLA-sensitized patients: challenges and solutions

    Directory of Open Access Journals (Sweden)

    Kim IK

    2014-09-01

    Full Text Available Irene K Kim, Ashley Vo, Stanley C Jordan Transplant Immunotherapy Program, Comprehensive Transplant Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA Abstract: Despite better understanding of the impact of development of the human leukocyte antigen (HLA antibody and numerous advancements in immunosuppressive therapy, the ability to successfully transplant highly sensitized patients remains a significant challenge. As the percentage of the waiting list becomes increasingly populated with highly sensitized patients, there is a growing demand for effective strategies to manage these patients. Over the past 20 years, desensitization therapies have been modified and developed, and are mainly utilized at transplant centers that have developed expertise. In addition, recognition that the highly sensitized patient population is disadvantaged on the transplant waiting list has led to recent changes in national kidney allocation policy. Furthermore, creative strategies, such as enrollment of sensitized patients into paired kidney exchange programs, have been developed to find compatible matches for these patients. The goal of this article is to address some of the specific challenges related to transplanting the highly sensitized patient at a high-volume transplant center with experience in desensitization and to review established and emerging solutions to help this patient population. Keywords: human leukocyte antigen, antibodies, desensitization, high-dose intravenous immunoglobulin, rituximab

  6. Mutagen sensitivity has high heritability: evidence from a twin study.

    Science.gov (United States)

    Wu, Xifeng; Spitz, Margaret R; Amos, Christopher I; Lin, Jie; Shao, Lina; Gu, Jian; de Andrade, Mariza; Benowitz, Neal L; Shields, Peter G; Swan, Gary E

    2006-06-15

    Despite numerous studies showing that mutagen sensitivity is a cancer predisposition factor, the heritability of mutagen sensitivity has not been clearly established. In this report, we used a classic twin study design to examine the role of genetic and environmental factors on the mutagen sensitivity phenotype. Mutagen sensitivity was measured in peripheral blood lymphocytes from 460 individuals [148 pairs of monozygotic (MZ) twins, 57 pairs of dizygotic (DZ) twins, and 50 siblings]. The intraclass correlation coefficients were all significantly higher in MZ twins than in dizygotes (DZ pairs and MZ-sibling pairs combined) for sensitivity to four different mutagen challenges. Applying biometric genetic modeling, we calculated a genetic heritability of 40.7%, 48.0%, 62.5%, and 58.8% for bleomycin, benzo[a]pyrene diol epoxide, gamma-radiation, and 4-nitroquinoline-1-oxide sensitivity, respectively. This study provides the strongest and most direct evidence that mutagen sensitivity is highly heritable, thereby validating the use of mutagen sensitivity as a cancer susceptibility factor.

  7. Determining neutrino absorption spectra at Ultra-High Energies

    CERN Document Server

    Scholten, Olaf

    2008-01-01

    The Low-Frequency Array (LOFAR), which will be available in the near future, will have an un-precedented sensitivity to measure the flux of Ultra-high energy (UHE) neutrinos. As such it promises to be ultimately suited for determining absorption lines in the neutrino spectrum as predicted by the absorption on the low-energy relic anti-neutrino background through the Z-boson resonance. The position of this absorption peak is sensitive to the neutrino mass and the redshift of the source. The most sensitive way to measure UHE neutrinos is via emitted radio waves when they impact on the moon. In this work we investigate the sensitivity of this detection method to the predicted absorption structures in the neutrino spectrum. A new generation of low-frequency digital radio telescopes will provide excellent detection capabilities for measuring these radio pulses, thus making our consideration here very timely.

  8. Achieving sensitive, high-resolution laser spectroscopy at CRIS

    Energy Technology Data Exchange (ETDEWEB)

    Groote, R. P. de [Instituut voor Kern- en Stralingsfysica, KU Leuven (Belgium); Lynch, K. M., E-mail: kara.marie.lynch@cern.ch [EP Department, CERN, ISOLDE (Switzerland); Wilkins, S. G. [The University of Manchester, School of Physics and Astronomy (United Kingdom); Collaboration: the CRIS collaboration

    2017-11-15

    The Collinear Resonance Ionization Spectroscopy (CRIS) experiment, located at the ISOLDE facility, has recently performed high-resolution laser spectroscopy, with linewidths down to 20 MHz. In this article, we present the modifications to the beam line and the newly-installed laser systems that have made sensitive, high-resolution measurements possible. Highlights of recent experimental campaigns are presented.

  9. A highly sensitive optical detector for use in deep underwater.

    Science.gov (United States)

    Hanada, H.; Hayashino, T.; Ito, M.; Iwasaki, A.; Kawamorita, K.; Kawamoto, H.; Matsumoto, T.; Narita, S.; Takayama, T.; Tanaka, S.; Yamaguchi, A.; Aoki, T.; Mitsui, K.; Ohashi, Y.; Okada, A.; Fukawa, M.; Uehara, S.; Bolesta, J. W.; Gorham, P. W.; Kondo, S.; Learned, J. G.; Matsuno, S.; Mignard, M.; Mitiguy, R.; O'Connor, D. J.; Peterson, V. Z.; Roberts, A.; Rosen, M.; Stenger, V. J.; Takemori, D.; Wilkins, G.; Grieder, P. K. F.; Minkowski, P.; Kitamura, T.; Camerini, U.; Grogan, W.; Jaworski, M.; March, R.; Narita, T.; Nicklaus, D.

    1998-05-01

    The authors have developed an optical detector module for use in deep underwater experiments that will search for high-energy neutrinos from cosmic rays and astronomical sources. This module is sensitive to single photons, is operable under high pressure, functions automatically and is remotely controlled.

  10. Sensitive Determination of DNA by RLS Enhancement of Metal Ions

    Institute of Scientific and Technical Information of China (English)

    Huang Jian-ping; Chen Fang; Ai Xin-ping; He Zhi-ke

    2004-01-01

    The interactions between metal ions and DNA have been studied by the resonance light scattering (RLS) spectra. In the acidic condition, the RLS signals of metal ions, especially the transition metal ions in group ⅠB and ⅡB, were increased by DNA. And it is found that the enhancement of RLS signals is linear to the concentration of DNA, so the RLS method for DNA determination was proposed in the presence of Cu2+. On the optimum conditions, the linear range and the detect limit of ctDNA is 4×10-8-4×10-6 g·5mL-1 and 1.13×10-8 g·5mL-1, respectively. The proposed method is successfully applied to determine the extracted plasmid DNA of Bacillus subtilis DB104.

  11. Is skin penetration a determining factor in skin sensitization ...

    Science.gov (United States)

    Summary:Background. It is widely accepted that substances that cannot penetrate through the skin will not be sensitisers. Thresholds based on relevant physicochemical parameters such as a LogKow > 1 and a MW 1 is a true requirement for sensitisation.Methods. A large dataset of substances that had been evaluated for their skin sensitisation potential, together with measured LogKow values was compiled from the REACH database. The incidence of skin sensitisers relative to non-skin sensitisers below and above the LogKow = 1 threshold was evaluated. Results. 1482 substances with associated skin sensitisation outcomes and measured LogKow values were identified. 305 substances had a measured LogKow skin sensitisation above and below the LogKow = 1 threshold. Reaction chemistry considerations could explain the skin sensitisation observed for the 38 sensitisers with a LogKow skin sensitisation potential and potency. Using the REACH data extracted to test out the validity of common assumptions in the skin sensitization AOP. Builds on trying to develop a proof of concept IATA

  12. Highly Accurate Sensor for High-Purity Oxygen Determination Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this STTR effort, Los Gatos Research (LGR) and the University of Wisconsin (UW) propose to develop a highly-accurate sensor for high-purity oxygen determination....

  13. Sensitive spectrophotometric determination of aluminium using thermal lens spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, R.D.; Snook, R.D. (Manchester Univ. (United Kingdom). Inst. of Science and Technology)

    1991-10-01

    The determination of Al{sup 3=} in solution using a continuous-wave mode mismatched thermal lens spectrometer is reported and two spectro-photometric procedures are compared. The reagent systems investigated were bromopyrogallol red-tetradecyltrimethylammonium bromide (BPR-TDTA) and chrome azurol S-cetylpyridinium chloride (CAS-CPC). The CAS-CPC system gave a superior detection limit (0.17 {mu}g l{sup -1}) to the BPR-TDTA system (1.15 mg l{sup -1}) owing to the higher reagent blanks and concomitant laser noise in the latter system. (author). 24 refs.; 6 figs.; 2 tabs.

  14. Research of High Sensitivity Uncooled Infrared Detector Array

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Pingchuan [Huazhong University of Science and Technology, Wuhan 430074 (China); Zhang, Bo, E-mail: redmoon123456@126.com, E-mail: lhzyzb@126.com [Luohe Vocational Technology College, Luohe 462002 (China)

    2011-02-01

    The infrared thermal imaging technology has been widely used in military and civilian fields and the field of the infrared detection and infrared thermal imaging technology has been of concern for a long time. On infrared thermal imaging, its core components for the infrared focal plane arrays, how to develop a high sensitivity of the multi-focal plane infrared detector is a key issue. Although the Common focal plane array of quantum has high sensitivity, but it requires low temperature cooling work environment and led to complexity and high cost, difficult to compact. Conventional uncooled infrared focal plane array is contrast to the quantum focal plane arrays. Therefore, this article preceded by the uncooled infrared detector array to improve the wide temperature sensitivity in examining the feasibility PMN composite film, materials composition, structure design and preparation process technology.

  15. Electro chemical Aptasensor Based on Prussian Blue-Chitosan-Glutaraldehyde for the Sensitive Determination of Tetracycline

    Institute of Scientific and Technical Information of China (English)

    Guanghui Shen; Yemin Guo; Xia Sun∗; Xiangyou Wang

    2014-01-01

    In this paper, a novel and sensitive electrochemical aptasensor for detecting tetracycline (TET) with prussian blue (PB) as the label-free signal was fabricated. A PB-chitosan-glutaraldehyde (PB-CS-GA) system acting as the signal indicator was developed to improve the sensitivity of the electrochemical aptasensor. Firstly, the PB-CS-GA was fixed onto the glass carbon electrode surface. Then, colloidal gold nanoparticles (AuNPs) were droped onto the electrode to immobilize the anti-TET aptamer for preparation of the aptasensor. The stepwise assembly process of the aptasensor was characterized by cyclic voltammetry (C-V) and scanning electron microscope (SEM). The target TET captured onto the electrode induced the current response of the electrode due to the non-conducting biomoleculars. Under the optimum operating conditions, the response of differential pulse voltammetry (DPV) was used for detecting the concentration of TET. The proposed aptasensor showed a high sensitivity and a wide linear range of 10−9 ∼ 10−5 M and 10−5 ∼ 10−2 M with the correlation coefficients of 0.994 and 0.992, respectively. The detection limit was 3.2×10−10 M (RSD 4.12%). Due to its rapidity, sensitivity and low cost, the proposed aptasensor could be used as a pre-scanning method in TET determination for the analysis of livestock products.

  16. Determining Regional Sensitivity to Energy-Related Water Withdrawals in Minnesota

    Science.gov (United States)

    McCulloch, A.; Brauman, K. A.

    2015-12-01

    Minnesota has abundant freshwater resources, yet concerns about water-impacts of energy and mining development are increasing. Statewide, total annual water withdrawals have increased, and, in some watersheds, withdrawals make up a large fraction of available water. The energy and mining sectors play a critical role in determining water availability, as water is used to irrigate biofuel feedstock crops, cool thermoelectric plants, and process and transport fuels and iron ore. We evaluated the Minnesota Department of Natural Resources (DNR) Water and Reporting System (MPARS) dataset (1988-2014) to identify regions where energy and mining-related water withdrawals are high or where they are increasing. The energy and mining sectors account for over 65 percent of total water extractions in Minnesota, but this percentage is greater in some regions. In certain southern and northeastern Minnesota watersheds, these extractions account for 90 percent of total water demand. Sensitivity to these demands is not dependent on total water demand alone, and is also not uniform among watersheds. We identified and evaluated factors influencing sensitivity, including population, extraction type (surface water or groundwater), percentage of increased demand, and whether withdrawals are consumptive or not. We determined that southern Minnesota is particularly sensitive to increased water demands, because of growing biofuel and sand extraction industries (the products of which are used in hydraulic fracturing). In the last ten years, ethanol production in Minnesota has increased by 440 percent, and over fifteen refineries (each with a capacity over 1.1 billion gallons), have been built. These users primarily extract from surface water bodies within a few watersheds, compromising local supplies. As these energy-related industries continue to grow, so will the demand for freshwater resources. Determining regional sensitivity to increased demands will allow policy-makers to manage the

  17. A sensitive fluorescence quenching method for determination of bismuth with tiron

    Energy Technology Data Exchange (ETDEWEB)

    Taher, Mohammad Ali; Rahimi, Mina [Department of Chemistry, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Fazelirad, Hamid, E-mail: hamidfazelirad@gmail.com [Department of Chemistry, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Department of Chemistry, Science and Research Branch, Islamic Azad University, Yazd (Iran, Islamic Republic of); Young Researchers Society, Shahid Bahonar University of Kerman, P.O. Box 76175-133, Kerman (Iran, Islamic Republic of)

    2014-01-15

    We describe a fluorescence quenching method for determination of bismuth with tiron. The method is based on the reaction of tiron by bismuth(III) in acidic media. The influence of variables such as the pH, type of buffer, tiron concentration, reaction time and temperature were investigated. Under optimized conditions, the fluorescence quenching extent is proportional to the concentration of bismuth for Bi–tiron system at the range 0.13–2.09 μg mL{sup −1} and the detection limit is 0.05 μg mL{sup −1}. The proposed sensor presented good repeatability, evaluated in terms of relative standard deviation (R.S.D.=±0.498%) for 11 replicates. This sensitive, rapid and accurate method has been successfully applied to the determination of trace bismuth(III) in water and hair samples and certified reference materials. -- Highlights: • No previous paper report on use of fluorescence quenching for determination of Bi. • Fluorescence quenching of trion is a sensitive method for determination of Bi(III). • Under the optimum conditions the detection limit is very low (0.05 μg mL{sup −1}). • The procedure is simple and safe and has high tolerance limit to interferences.

  18. Highly sensitive optical sensor system for blood leakage detection

    Science.gov (United States)

    Ueda, Masahiro; Ishikawa, Kazuhiko; Jie, Chen; Sanae, Mizuno; Touma, Yasunori

    A highly sensitive method for the detection of blood leakage has been developed, and a practical sensor system for blood concentration measurement has been constructed. The present method is based on the attenuation of laser light by blood cells. The effects of the fluctuations of the incident laser light power are eliminated by normalizing the attenuated light intensity by the incident light intensity. A part of the incident laser light is reflected by a beam splitter mounted at the entrance of the test cell, of which the power is measured to provide base data for normalization. The optical path is extended to enhance sensitivity by using a pair of side mirrors. This multi-reflection method is very effective to increase sensitivity; the maximum sensitivity obtained for blood concentration is about 4 X 10 -6 by volume, which is significantly higher than that of the conventional sensors.

  19. Scalable photonic crystal chips for high sensitivity protein detection.

    Science.gov (United States)

    Liang, Feng; Clarke, Nigel; Patel, Parth; Loncar, Marko; Quan, Qimin

    2013-12-30

    Scalable microfabrication technology has enabled semiconductor and microelectronics industries, among other fields. Meanwhile, rapid and sensitive bio-molecule detection is increasingly important for drug discovery and biomedical diagnostics. In this work, we designed and demonstrated that photonic crystal sensor chips have high sensitivity for protein detection and can be mass-produced with scalable deep-UV lithography. We demonstrated label-free detection of carcinoembryonic antigen from pg/mL to μg/mL, with high quality factor photonic crystal nanobeam cavities.

  20. Experimental Investigation on a Highly Sensitive Atomic Magnetometer

    Institute of Scientific and Technical Information of China (English)

    LI Shu-Guang; XU Yun-Fei; WANG Zhao-Ying; LIU Yun-Xian; LIN Qiang

    2009-01-01

    A highly sensitive all-optical atomic magnetometer based on the magnetooptical effect which uses the advanced technique of single laser beam detection is reported and demonstrated experimentally.A sensitivityof 0.5 pT/Hz1/2 is obtained by analyzing the magnetic noise spectrum,which exceeds that of most traditional magnetometers.This kind of atomic magnetometer is very compact,has a low power consumption,and has a high theoretical sensitivity limit,which make it suitable for many applications.

  1. High-sensitivity, high-speed continuous imaging system

    Science.gov (United States)

    Watson, Scott A; Bender, III, Howard A

    2014-11-18

    A continuous imaging system for recording low levels of light typically extending over small distances with high-frame rates and with a large number of frames is described. Photodiode pixels disposed in an array having a chosen geometry, each pixel having a dedicated amplifier, analog-to-digital convertor, and memory, provide parallel operation of the system. When combined with a plurality of scintillators responsive to a selected source of radiation, in a scintillator array, the light from each scintillator being directed to a single corresponding photodiode in close proximity or lens-coupled thereto, embodiments of the present imaging system may provide images of x-ray, gamma ray, proton, and neutron sources with high efficiency.

  2. High throughput modular chambers for rapid evaluation of anesthetic sensitivity

    Directory of Open Access Journals (Sweden)

    Eckmann David M

    2006-11-01

    Full Text Available Abstract Background Anesthetic sensitivity is determined by the interaction of multiple genes. Hence, a dissection of genetic contributors would be aided by precise and high throughput behavioral screens. Traditionally, anesthetic phenotyping has addressed only induction of anesthesia, evaluated with dose-response curves, while ignoring potentially important data on emergence from anesthesia. Methods We designed and built a controlled environment apparatus to permit rapid phenotyping of twenty-four mice simultaneously. We used the loss of righting reflex to indicate anesthetic-induced unconsciousness. After fitting the data to a sigmoidal dose-response curve with variable slope, we calculated the MACLORR (EC50, the Hill coefficient, and the 95% confidence intervals bracketing these values. Upon termination of the anesthetic, Emergence timeRR was determined and expressed as the mean ± standard error for each inhaled anesthetic. Results In agreement with several previously published reports we find that the MACLORR of halothane, isoflurane, and sevoflurane in 8–12 week old C57BL/6J mice is 0.79% (95% confidence interval = 0.78 – 0.79%, 0.91% (95% confidence interval = 0.90 – 0.93%, and 1.96% (95% confidence interval = 1.94 – 1.97%, respectively. Hill coefficients for halothane, isoflurane, and sevoflurane are 24.7 (95% confidence interval = 19.8 – 29.7%, 19.2 (95% confidence interval = 14.0 – 24.3%, and 33.1 (95% confidence interval = 27.3 – 38.8%, respectively. After roughly 2.5 MACLORR • hr exposures, mice take 16.00 ± 1.07, 6.19 ± 0.32, and 2.15 ± 0.12 minutes to emerge from halothane, isoflurane, and sevoflurane, respectively. Conclusion This system enabled assessment of inhaled anesthetic responsiveness with a higher precision than that previously reported. It is broadly adaptable for delivering an inhaled therapeutic (or toxin to a population while monitoring its vital signs, motor reflexes, and providing precise control

  3. Determinants of High Schools' Advanced Course Offerings

    Science.gov (United States)

    Iatarola, Patrice; Conger, Dylan; Long, Mark C.

    2011-01-01

    This article examines the factors that determine a high school's probability of offering Advanced Placement (AP) and International Baccalaureate (IB) courses. The likelihood that a school offers advanced courses, and the number of sections that it offers, is largely driven by having a critical mass of students who enter high school with…

  4. New approaches to donor crossmatching and successful transplantation of highly sensitized patients.

    Science.gov (United States)

    Delmonico, F L; Fuller, A; Cosimi, A B; Tolkoff-Rubin, N; Russell, P S; Rodey, G E; Fuller, T C

    1983-12-01

    A class I HLA molecule may bear not only a private or unique determinant, but a shared, yet discrete, public epitope. These public determinants occur with a much higher frequency in the random donor population than the associated private determinants--and thus, are encountered more often in random donor blood transfusions and in renal transplantation. Sera from highly sensitized dialysis patients have been reported to contain a restricted number of antibodies to public determinants rather than a diverse array of antibodies directed against the private HLA-AB epitopes. As detailed in this report, comprehensive serum analysis of the public antibodies in highly sensitized transplant candidates has optimized identification of potential crossmatch-compatible donors and has avoided needless crossmatches. During the past two years, the incidence of renal transplantation from cadaveric donors to highly sensitized recipients has doubled at this institution. At 10-25 months following transplantation, 70% of these allografts are functioning. Private HLA class I antigen incompatibility was not a barometer for exclusion in the final donor crossmatch of these highly sensitized recipients. Furthermore, positive donor T cell crossmatches with sera obtained more than six months prior to transplantation may not represent an impediment to successful transplantation. We conclude that the approach of detailed antibody analysis can result in an improved outlook for successful transplantation of more dialysis patients who are highly sensitized to the class I HLA alloantigens.

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

    Directory of Open Access Journals (Sweden)

    Ibrahim A. Darwish

    2008-01-01

    Full Text Available 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.

  6. Large pi-aromatic molecules as potential sensitizers for highly efficient dye-sensitized solar cells.

    Science.gov (United States)

    Imahori, Hiroshi; Umeyama, Tomokazu; Ito, Seigo

    2009-11-17

    Recently, dye-sensitized solar cells have attracted much attention relevant to global environmental issues. Thus far, ruthenium(II) bipyridyl complexes have proven to be the most efficient TiO(2) sensitizers in dye-sensitized solar cells. However, a gradual increment in the highest power conversion efficiency has been recognized in the past decade. More importantly, considering that ruthenium is a rare metal, novel dyes without metal or using inexpensive metal are desirable for highly efficient dye-sensitized solar cells. Large pi-aromatic molecules, such as porphyrins, phthalocyanines, and perylenes, are important classes of potential sensitizers for highly efficient dye-sensitized solar cells, owing to their photostability and high light-harvesting capabilities that can allow applications in thinner, low-cost dye-sensitized solar cells. Porphyrins possess an intense Soret band at 400 nm and moderate Q bands at 600 nm. Nevertheless, the poor light-harvesting properties relative to the ruthenium complexes have limited the cell performance of porphyrin-sensitized TiO(2) cells. Elongation of the pi conjugation and loss of symmetry in porphyrins cause broadening and a red shift of the absorption bands together with an increasing intensity of the Q bands relative to that of the Soret band. On the basis of the strategy, the cell performance of porphyrin-sensitized solar cells has been improved intensively by the enhanced light absorption. Actually, some push-pull-type porphyrins have disclosed a remarkably high power conversion efficiency (6-7%) that was close to that of the ruthenium complexes. Phthalocyanines exhibit strong absorption around 300 and 700 nm and redox features that are similar to porphyrins. Moreover, phthalocyanines are transparent over a large region of the visible spectrum, thereby enabling the possibility of using them as "photovoltaic windows". However, the cell performance was poor, owing to strong aggregation and lack of directionality in the

  7. Aluminum nano-cantilevers for high sensitivity mass sensors

    DEFF Research Database (Denmark)

    Davis, Zachary James; Boisen, Anja

    2005-01-01

    We have fabricated Al nano-cantilevers using a very simple one mask contact UV lithography technique with lateral dimensions under 500 nm and vertical dimensions of approximately 100 nm. These devices are demonstrated as highly sensitive mass sensors by measuring their dynamic properties. Further...

  8. Highly Sensitive AMS Measurement of 53Mn at CIAE

    Institute of Scientific and Technical Information of China (English)

    DONG; Ke-jun; HU; Hao; LIU; Guang-shan; HE; Ming; LI; Zhen-yu; DOU; Liang; XIE; Lin-bo; LIU; Jian-cheng; WANG; Xiang-gao; SHEN; Hong-tao; LIN; De-yu; ZHENG; Guo-wen; WANG; Xiao-bo; LI; Heng; LI; Chao-li; WU; Shao-yong; YOU; Qu-bo; JIN; Chun-sheng; CHEN; Zhi-gang; YUAN; Jian; JIANG; Shan

    2013-01-01

    Methods for highly sensitive AMS measurement of 53Mn were explored by extracting different Mn-containing molecular ions in ion source and using different chemical forms of sample materials.Preliminary results indicate that a method for AMS measurement of 53Mn has been established and a-155355

  9. Sensitivity Study of Strapdown Inertial Sensors in High Performance Applications

    Science.gov (United States)

    1980-12-01

    system error varied with a change in heading 7K. ( xii 1 SENSITIVITY STUDY OF STRAPDOWN INERTIAL SENSORS IN HIGH PERFORMANCE APPLICATIONS I. Introduction...given in Tabla 10. 23 State Meaning o Basic Altitude Damped INS x(1) Error in East Longitude 5.7735 x 1O Ŗ arc min x(2) Error in North Latitude

  10. [Burner head with high sensitivity in atomic absorption spectroscopy].

    Science.gov (United States)

    Feng, X; Yang, Y

    1998-12-01

    This paper presents a burner head with gas-sample separate entrance and double access, which is used for atomic absorption spectroscopy. According to comparison and detection, the device can improve sensitivity by a factor of 1 to 5. In the meantime it has properties of high stability and resistance to interference.

  11. Microelectromechanical Resonant Accelerometer Designed with a High Sensitivity

    Science.gov (United States)

    Zhang, Jing; Su, Yan; Shi, Qin; Qiu, An-Ping

    2015-01-01

    This paper describes the design and experimental evaluation of a silicon micro-machined resonant accelerometer (SMRA). This type of accelerometer works on the principle that a proof mass under acceleration applies force to two double-ended tuning fork (DETF) resonators, and the frequency output of two DETFs exhibits a differential shift. The dies of an SMRA are fabricated using silicon-on-insulator (SOI) processing and wafer-level vacuum packaging. This research aims to design a high-sensitivity SMRA because a high sensitivity allows for the acceleration signal to be easily demodulated by frequency counting techniques and decreases the noise level. This study applies the energy-consumed concept and the Nelder-Mead algorithm in the SMRA to address the design issues and further increase its sensitivity. Using this novel method, the sensitivity of the SMRA has been increased by 66.1%, which attributes to both the re-designed DETF and the reduced energy loss on the micro-lever. The results of both the closed-form and finite-element analyses are described and are in agreement with one another. A resonant frequency of approximately 22 kHz, a frequency sensitivity of over 250 Hz per g, a one-hour bias stability of 55 μg, a bias repeatability (1σ) of 48 μg and the bias-instability of 4.8 μg have been achieved. PMID:26633425

  12. Microelectromechanical Resonant Accelerometer Designed with a High Sensitivity

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    2015-12-01

    Full Text Available This paper describes the design and experimental evaluation of a silicon micro-machined resonant accelerometer (SMRA. This type of accelerometer works on the principle that a proof mass under acceleration applies force to two double-ended tuning fork (DETF resonators, and the frequency output of two DETFs exhibits a differential shift. The dies of an SMRA are fabricated using silicon-on-insulator (SOI processing and wafer-level vacuum packaging. This research aims to design a high-sensitivity SMRA because a high sensitivity allows for the acceleration signal to be easily demodulated by frequency counting techniques and decreases the noise level. This study applies the energy-consumed concept and the Nelder-Mead algorithm in the SMRA to address the design issues and further increase its sensitivity. Using this novel method, the sensitivity of the SMRA has been increased by 66.1%, which attributes to both the re-designed DETF and the reduced energy loss on the micro-lever. The results of both the closed-form and finite-element analyses are described and are in agreement with one another. A resonant frequency of approximately 22 kHz, a frequency sensitivity of over 250 Hz per g, a one-hour bias stability of 55 μg, a bias repeatability (1σ of 48 μg and the bias-instability of 4.8 μg have been achieved.

  13. Determinants for patient satisfaction regarding aesthetic outcome and skin sensitivity after breast-conserving surgery.

    Science.gov (United States)

    Dahlbäck, Cecilia; Manjer, Jonas; Rehn, Martin; Ringberg, Anita

    2016-12-07

    With the development of new surgical techniques in breast cancer, such as oncoplastic breast surgery, increased knowledge of risk factors for poor satisfaction with conventional breast-conserving surgery (BCS) is needed in order to determine which patients to offer these techniques to. The aim of this study was to investigate patient satisfaction regarding aesthetic result and skin sensitivity in relation to patient, tumour, and treatment factors, in a consecutive sample of patients undergoing conventional BCS. Women eligible for BCS were recruited between February 1, 2008 and January 31, 2012 in a prospective setup. In all, 297 women completed a study-specific questionnaire 1 year after conventional BCS and radiotherapy. Potential risk factors for poor satisfaction were investigated using logistic regression analysis. The great majority of the women, 84%, were satisfied or very satisfied with the overall aesthetic result. The rate of satisfaction regarding symmetry between the breasts was 68% and for skin sensitivity in the operated breast it was 67%. Excision of more than 20% of the preoperative breast volume was associated with poor satisfaction regarding overall aesthetic outcome, as was axillary clearance. A high BMI (≥30 kg/m(2)) seemed to affect satisfaction with symmetry negatively. Factors associated with less satisfied patients regarding skin sensitivity in the operated breast were an excision of ≥20% of preoperative breast volume, a BMI of 25-30 kg/m(2), axillary clearance, and radiotherapy. Re-excision and postoperative infection were associated with lower rates of satisfaction regarding both overall aesthetic outcome and symmetry, as well as with skin sensitivity. Several factors affect patient satisfaction after BCS. A major determinant of poor satisfaction in this study was a large excision of breast volume. If the percentage of breast volume excised is estimated to exceed 20%, other techniques, such as oncoplastic breast surgery, with or

  14. A high sensitive biosensor based on FePt/CNTs nanocomposite/N-(4-hydroxyphenyl)-3,5-dinitrobenzamide modified carbon paste electrode for simultaneous determination of glutathione and piroxicam.

    Science.gov (United States)

    Karimi-Maleh, Hassan; Tahernejad-Javazmi, Fahimeh; Ensafi, Ali A; Moradi, Reza; Mallakpour, Shadpour; Beitollahi, Hadi

    2014-10-15

    This study describes the development, electrochemical characterization and utilization of novel modified N-(4-hydroxyphenyl)-3,5-dinitrobenzamide-FePt/CNTs carbon paste electrode for the electrocatalytic determination of glutathione (GSH) in the presence of piroxicam (PXM) for the first time. The synthesized nanocomposite was characterized with different methods such as TEM and XRD. The modified electrode exhibited a potent and persistent electron mediating behavior followed by well-separated oxidation peaks of GSH and PXM. The peak currents were linearly dependent on GSH and PXM concentrations in the range of 0.004-340 and 0.5-550 µmol L(-1), with detection limits of 1.0 nmol L(-1) and 0.1 µmolL(-1), respectively. The modified electrode was successfully used for the determination of the analytes in real samples with satisfactory results.

  15. Highly sensitive detection using microring resonator and nanopores

    Science.gov (United States)

    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.

  16. Quantum dots (QDs) based fluorescence probe for the sensitive determination of kaempferol

    Science.gov (United States)

    Tan, Xuanping; Liu, Shaopu; Shen, Yizhong; He, Youqiu; Yang, Jidong

    2014-12-01

    In this work, using the quenching of fluorescence of thioglycollic acid (TGA)-capped CdTe quantum dots (QDs), a novel method for the determination of kaempferol (KAE) has been developed. Under optimum conditions, a linear calibration plot of the quenched fluorescence intensity at 552 nm against the concentration of KAE was observed in the range of 4-44 μg mL-1 with a detection limit (3σ/K) of 0.79 μg mL-1. In addition, the detailed reaction mechanism has also been proposed on the basis of electron transfer supported by ultraviolet-visible (UV-vis) absorption and fluorescence (FL) spectroscopy. The method has been applied for the determination of KAE in pharmaceutical preparations with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.

  17. Highly Mass-Sensitive Thin Film Plate Acoustic Resonators (FPAR)

    Science.gov (United States)

    Arapan, Lilia; Alexieva, Gergana; Avramov, Ivan D.; Radeva, Ekaterina; Strashilov, Vesseline; Katardjiev, Ilia; Yantchev, Ventsislav

    2011-01-01

    The mass sensitivity of thin aluminum nitride (AlN) film S0 Lamb wave resonators is theoretically and experimentally studied. Theoretical predictions based on modal and finite elements method analysis are experimentally verified. Here, two-port 888 MHz synchronous FPARs are micromachined and subsequently coated with hexamethyl-disiloxane(HMDSO)-plasma-polymerized thin films of various thicknesses. Systematic data on frequency shift and insertion loss versus film thickness are presented. FPARs demonstrate high mass-loading sensitivity as well as good tolerance towards the HMDSO viscous losses. Initial measurements in gas phase environment are further presented. PMID:22163994

  18. Highly mass-sensitive thin film plate acoustic resonators (FPAR).

    Science.gov (United States)

    Arapan, Lilia; Alexieva, Gergana; Avramov, Ivan D; Radeva, Ekaterina; Strashilov, Vesseline; Katardjiev, Ilia; Yantchev, Ventsislav

    2011-01-01

    The mass sensitivity of thin aluminum nitride (AlN) film S0 Lamb wave resonators is theoretically and experimentally studied. Theoretical predictions based on modal and finite elements method analysis are experimentally verified. Here, two-port 888 MHz synchronous FPARs are micromachined and subsequently coated with hexamethyl-disiloxane(HMDSO)-plasma-polymerized thin films of various thicknesses. Systematic data on frequency shift and insertion loss versus film thickness are presented. FPARs demonstrate high mass-loading sensitivity as well as good tolerance towards the HMDSO viscous losses. Initial measurements in gas phase environment are further presented.

  19. Design and Fabrication of High Sensitive Piezoresistive MEMS Accelerometer

    Directory of Open Access Journals (Sweden)

    JOSHI A.B

    2008-04-01

    Full Text Available This paper addresses the design and fabrication of high sensitive single axis piezoresistive micro-accelerometer for 50 g application. MEMS based accelerometer structure comprise of flexure fixed at one end and having attached proof mass at other end. This structure is designed and simulated using Coventorware. The simulation results show the sensitivity of 4mV/g. The structure is fabricated in N type silicon (100 substrate using Silicon bulk micromachining. This paper also discuses the use of PECVD Si3N4 layer as a masking material for silicon micromachining and process flow for accelerometer.

  20. Cardiac troponins and high-sensitivity cardiac troponin assays.

    Science.gov (United States)

    Conrad, Michael J; Jarolim, Petr

    2014-03-01

    Measurement of circulating cardiac troponins I and T has become integral to the diagnosis of myocardial infarction. This article discusses the structure and function of the troponin complex and the release of cardiac troponin molecules from the injured cardiomyocyte into the circulation. An overview of current cardiac troponin assays and their classification according to sensitivity is presented. The diagnostic criteria, role, and usefulness of cardiac troponin for myocardial infarction are discussed. In addition, several examples are given of the usefulness of high-sensitivity cardiac troponin assays for short-term and long-term prediction of adverse events.

  1. Highly Mass-Sensitive Thin Film Plate Acoustic Resonators (FPAR

    Directory of Open Access Journals (Sweden)

    Ventsislav Yantchev

    2011-07-01

    Full Text Available The mass sensitivity of thin aluminum nitride (AlN film S0 Lamb wave resonators is theoretically and experimentally studied. Theoretical predictions based on modal and finite elements method analysis are experimentally verified. Here, two-port 888 MHz synchronous FPARs are micromachined and subsequently coated with hexamethyl-disiloxane(HMDSO-plasma-polymerized thin films of various thicknesses. Systematic data on frequency shift and insertion loss versus film thickness are presented. FPARs demonstrate high mass-loading sensitivity as well as good tolerance towards the HMDSO viscous losses. Initial measurements in gas phase environment are further presented.

  2. Coupling of Molecular Imprinted Polymer Nanoparticles by High Performance Liquid Chromatography as an Efficient Technique for Sensitive and Selective Trace Determination of 4-Chloro-2-Methylphenoxy Acetic Acid in Complex Matrices.

    Directory of Open Access Journals (Sweden)

    Fariborz Omidi

    2014-05-01

    Full Text Available 4-chloro-2-methylphenoxy acetic acid (MCPA is one of the most important pesticides which is extensively used to control weeds in arable farmland. Exposure to this compound occurs in general population and persons who occupationally handle it. The aim of this present work was the preparation of MCPA imprinting polymer and its application as a selective sample preparation technique for trace determination of MCPA in biological and environmental samples.In this study, MCPA imprinting polymer was obtained by precipitation polymerization using methacrylic acid (the functional monomer, ethylene glycol dimethacrylate (the cross-linker, 2, 2'-azobisisobutyronitrile (the initiator and MCPA (the template molecule in acetonitrile solution. The MIP-NPs were characterized by thermogravimetric analysis and scanning electron microscopy. The optimization process was carried out applying batch method. After optimization of the parameters, affecting the adsorption and desorption of analyte, urine and different water samples were used to determine MCPA.Imprinted MCPA molecules were removed from the polymeric structure using acetic acid in methanol (20:80 v/v % as the eluting solvent. Both sorption and desorption process occur within 10 min. The maximum sorbent capacity of the molecular imprinted polymer is 87.4 mg g-1. The relative standard deviation and limit of detection for water samples by introduced selective solid phase extraction were 4.8% and 0.9 μg L-1, and these data for urine samples were 4.5% and 1.60 μg L-1, respectively.The developed method was successfully applied to determine MCPA in urine and different water samples.

  3. High Sensitivity Very Low Frequency Receiver for Earthquake Data Acquisition.

    Science.gov (United States)

    Munir, A.; Najmurrokhman, A.

    2017-03-01

    high sensitivity very low frequency (VLF) receiver is developed based on AD744 monolithic operational amplifier (Op-Amp) for earthquake data acquisition. In research related natural phenomena such as atmospheric noise, lightning and earthquake, a VLF receiver particularly with high sensitivity is utterly required due to the low power of VLF wave signals received by the antenna. The developed receiver is intended to have high sensitivity reception for the signals in frequency range of 10-30kHz allocated for earthquake observation. The VLF receiver which is portably designed is also equipped with an output port connectable to the soundcard of personal computer for further data acquisition. After obtaining the optimum design, the hardware realization is implemented on a printed circuit board (PCB) for experimental characterization. It shows that the sensitivity of realized VLF receiver is almost linear in the predefined frequency range for the input signals lower than -12dBm and to be quadratic for the higher level input signals.

  4. High Sensitivity Polymer Optical Fiber-Bragg-Grating-Based Accelerometer

    DEFF Research Database (Denmark)

    Stefani, Alessio; Andresen, Søren; Yuan, Wu

    2012-01-01

    We report on the fabrication and characterization of the first accelerometer based on a polymer optical fiber Bragg grating (FBG) for operation at both 850 and 1550 nm. The devices have a flat frequency response over a 1-kHz bandwidth and a resonance frequency of about 3 kHz. The response is linear...... up to at least 15 g and sensitivities as high as 19 pm/g (shift in resonance wavelength per unit acceleration) have been demonstrated. Given that 15 g corresponds to a strain of less than 0.02% and that polymer fibers have an elastic limit of more than 1%, the polymer FBG accelerometer can measure...... very strong accelerations. We compare with corresponding silica FBG accelerometers and demonstrate that using polymer FBGs improves the sensitivity by more than a factor of four and increases the figure of merit, defined as the sensitivity times the resonance frequency squared....

  5. Sensitive and selective magnetoimmunosensing platform for determination of the food allergen Ara h 1

    Energy Technology Data Exchange (ETDEWEB)

    Montiel, V. Ruiz-Valdepeñas, E-mail: victor_lega90@hotmail.com [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Campuzano, S., E-mail: susanacr@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Pellicanò, A., E-mail: alessandro.pellicano@unimi.it [Department of Food, Environmental and Nutritional Sciences (DEFENS), University of Milan, Via Celoria 2, 20133 Milan (Italy); Torrente-Rodríguez, R.M., E-mail: rebeca.magnolia@gmail.com [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Reviejo, A.J., E-mail: reviejo@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Cosio, M.S., E-mail: stella.cosio@unimi.it [Department of Food, Environmental and Nutritional Sciences (DEFENS), University of Milan, Via Celoria 2, 20133 Milan (Italy); Pingarrón, J.M., E-mail: pingarro@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2015-06-23

    Highlights: • First amperometric magnetoimmunosensor for Ara h 1 determination. • Sensitive and selective detection of Ara h 1 in 2 h. • LOD of 6.3 ng mL{sup −1}. • Determinations in food extracts and saliva. • Potential applicability in food safety and consumer protection. - Abstract: A highly sensitive disposable amperometric immunosensor based on the use of magnetic beads (MBs) is described for determination of Ara h 1, the major peanut allergen, in only 2 h. The approach uses a sandwich configuration involving selective capture and biotinylated detector antibodies and carboxylic acid-modified MBs (HOOC-MBs). The MBs bearing the immunoconjugates are captured by a magnet placed under the surface of a disposable screen-printed carbon electrode (SPCE) and the affinity reactions are monitored amperometrically at −0.20 V (vs a Ag pseudo-reference electrode) in the presence of hydroquinone (HQ) as electron transfer mediator and upon addition of H{sub 2}O{sub 2} as the enzyme substrate. The developed immunosensor exhibits a wide range of linearity between 20.8 and 1000.0 ng mL{sup −1} Ara h 1, a detection limit of 6.3 ng mL{sup −1}, a great selectivity, a good reproducibility with a RSD of 6.3% for six different immunosensors and a useful lifetime of 25 days. The usefulness of the immunosensor was demonstrated by determining Ara h 1 in different matrices (food extracts and saliva). The results correlated properly with those provided by a commercial ELISA method offering a reliable and promising analytical screening tool in the development of user-friendly devices for on-site determination of Ara h 1.

  6. Are Inflationary Predictions Sensitive to Very High Energy Physics?

    CERN Document Server

    Burgess, C P; Lemieux, F; Holman, R

    2003-01-01

    It has been proposed that the successful inflationary description of density perturbations on cosmological scales is sensitive to the details of physics at extremely high (trans-Planckian) energies. We test this proposal by examining how inflationary predictions depend on higher-energy scales within a simple model where the higher-energy physics is well understood. We find the best of all possible worlds: inflationary predictions are robust against the vast majority of high-energy effects, but can be sensitive to some effects in certain circumstances, in a way which does not violate ordinary notions of decoupling. This implies both that the comparison of inflationary predictions with CMB data is meaningful, and that it is also worth searching for small deviations from the standard results in the hopes of learning about very high energies.

  7. Design of highly sensitive multichannel bimetallic photonic crystal fiber biosensor

    Science.gov (United States)

    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.

  8. Sensitivity of HAWC to high-mass dark matter annihilations

    Science.gov (United States)

    Abeysekara, A. U.; Alfaro, R.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Ayala Solares, H. A.; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Becerra Gonzalez, J.; Belmont, E.; BenZvi, S. Y.; Berley, D.; Bonilla Rosales, M.; Braun, J.; Caballero-Lopez, R. A.; Caballero-Mora, K. S.; Carramiñana, A.; Castillo, M.; Cotti, U.; Cotzomi, J.; de la Fuente, E.; De León, C.; DeYoung, T.; Diaz Hernandez, R.; Diaz-Cruz, L.; Díaz-Vélez, J. C.; Dingus, B. L.; DuVernois, M. A.; Ellsworth, R. W.; Fiorino, D. W.; Fraija, N.; Galindo, A.; Garfias, F.; González, M. M.; Goodman, J. A.; Grabski, V.; Gussert, M.; Hampel-Arias, Z.; Harding, J. P.; Hui, C. M.; Hüntemeyer, P.; Imran, A.; Iriarte, A.; Karn, P.; Kieda, D.; Kunde, G. J.; Lara, A.; Lauer, R. J.; Lee, W. H.; Lennarz, D.; León Vargas, H.; Linares, E. C.; Linnemann, J. T.; Longo, M.; Luna-Garcia, R.; Marinelli, A.; Martinez, H.; Martinez, O.; Martínez-Castro, J.; Matthews, J. A. J.; McEnery, J.; Mendoza Torres, E.; Miranda-Romagnoli, P.; Moreno, E.; Mostafá, M.; Nellen, L.; Newbold, M.; Noriega-Papaqui, R.; Oceguera-Becerra, T.; Patricelli, B.; Pelayo, R.; Pérez-Pérez, E. G.; Pretz, J.; Rivière, C.; Rosa-González, D.; Ryan, J.; Salazar, H.; Salesa, F.; Sanchez, F. E.; Sandoval, A.; Schneider, M.; Silich, S.; Sinnis, G.; Smith, A. J.; Sparks Woodle, K.; Springer, R. W.; Taboada, I.; Toale, P. A.; Tollefson, K.; Torres, I.; Ukwatta, T. N.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Wisher, I. G.; Wood, J.; Yodh, G. B.; Younk, P. W.; Zaborov, D.; Zepeda, A.; Zhou, H.; Abazajian, K. N.; Milagro Collaboration

    2014-12-01

    The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19° North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi-TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from nonluminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross sections below thermal. HAWC should also be sensitive to nonthermal cross sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained.

  9. Simple and sensitive high-performance liquid chromatographic method for the determination of 1,5-benzodiazepine clobazam and its active metabolite N-desmethylclobazam in human serum and urine with application to 1,4-benzodiazepines analysis.

    Science.gov (United States)

    Kunicki, P K

    2001-01-05

    A HPLC-UV determination of clobazam and N-desmethylclobazam in human serum and urine is presented. After simple liquid-liquid extraction with dichloromethane the compounds and an internal standard diazepam were separated on a Supelcosil LC-8-DB column at ambient temperature under isocratic conditions using the mobile phase: CH3CN-water-0.5 M KH2PO4-H3PO4 (440:540:20:0.4, v/v and 360:580:60:0.4, v/v for serum and urine, respectively). The detection was performed at 228 nm with limits of quantification of 2 ng/ml for serum and 1 ng/ml for urine. Relative standard deviations for intra- and inter-assay precision were found below 8% for both compounds for all the tested concentrations. The described procedure may be easily adapted for several 1,4-benzodiazepines.

  10. Selective and sensitive determination of dopamine by composites of polypyrrole and graphene modified electrodes.

    Science.gov (United States)

    Si, Peng; Chen, Hailan; Kannan, Palanisamy; Kim, Dong-Hwan

    2011-12-21

    A novel method is developed to fabricate the polypyrrole (PPy) and graphene thin films on electrodes by electrochemical polymerization of pyrrole with graphene oxide (GO) as a dopant, followed by electrochemical reduction of GO in the composite film. The composite of PPy and electrochemically reduced graphene oxide (eRGO)-modified electrode is highly sensitive and selective toward the detection of dopamine (DA) in the presence of high concentrations of ascorbic acid (AA) and uric acid (UA). The sensing performance of the PPy/eRGO-modified electrode is investigated by differential pulse voltammetry (DPV), revealing a linear range of 0.1-150 μM with a detection limit of 23 nM (S/N = 3). The practical application of the PPy/eRGO-modified electrode is successfully demonstrated for DA determination in human blood serum.

  11. A novel highly sensitive and selective optical sensor based on a symmetric tetradentate Schiff-base embedded in PVC polymeric film for determination of Zn{sup 2+} ion in real samples

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Aziz, Ayman A., E-mail: aymanaziz31@gmail.com [Chemistry Department, Faculty of Science, Ain Shams University, 11566 Cairo (Egypt); Chemistry Department, Faculty of Science, University of Tabuk, 71421, Tabuk (Saudi Arabia)

    2013-11-15

    A novel prepared Zn{sup 2+} ion PVC membrane sensor based on a novel Schiff base; N,N′bis(salicylaldehyde)2,3-diaminonaphthalene (SDN) for the determination of Zn{sup 2+} ion was described. The chemosensor was synthesized under microwave irradiation via condensation of 2,3-diaminonaphthalene and salicylaldehyde. Photoluminescence characteristics of the novel Schiff base ligand were investigated in different solvents including dicholoromethane (DCM), tetrahydrofuran (THF) and ethanol (EtOH). SDN was found to have higher emission intensity and Stoke’s shift value (Δλ{sub ST}) in EtOH solution. The sensor exhibited a specific fluorescent on response to Zn{sup 2+}. The response of the sensor is based on the fluorescence enhancement of SDN (LH{sub 2}) by Zn{sup 2+} ion as a result of formation the rigid structure L-Zn complex. The experiment results also show that the response behavior of SDN to Zn{sup 2+} is pH independent in the range of pH 6.0–8.0. At pH 7.0, the proposed sensor displays a calibration response for Zn{sup 2+} over a wide concentration range of 1.0×10{sup −9}–2.0×10{sup −3} mol L{sup −1} with a limit of detection (LOD) 8.1×10{sup −10} mol L{sup −1} (0.0529659 μg L{sup −1}). The sensor shows excellent selectivity toward Zn{sup 2+} with respect to common coexisting cations. The proposed fluorescence optode was successfully applied to detect Zn{sup 2+} in human hair samples, different brands of powdered milk and some pharmaceuticals. -- Highlights: • A novel Zn(II) chemosensor has been developed. • Wide linear concentration range of 1.0×10{sup −9}–2.0×10{sup −3} mol L{sup −1}. • Application for determination of Zn(II) in real samples.

  12. Highly sensitive and rapid ultra-performance liquid chromatography-tandem mass spectrometry method for the determination of nifedipine in human plasma and its application to a bioequivalence study.

    Science.gov (United States)

    Patel, Daxesh P; Sharma, Primal; Sanyal, Mallika; Singhal, Puran; Shrivastav, Pranav S

    2012-12-01

    An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed for the determination of nifedipine in human plasma using nifedipine-d6 as the internal standard (IS). The plasma samples were prepared by solid-phase extraction on Phenomenex Strata-X cartridges employing 200 μL human plasma. Chromatography was carried out on Waters Acquity UPLC BEH C₁₈ (50 × 2.1 mm, 1.7 µm particle size) analytical column under isocratic conditions using a mobile phase consisting of 4.0 mm ammonium acetate-acetonitrile (15:85, v/v). The precursor → product ion transitions for nifedipine (m/z 347.2 → 315.2) and IS (m/z 353.1 → 318.1) were monitored on a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring and positive-ion mode. The method was validated over a wide dynamic concentration range of 0.050-150 ng/mL. Matrix effect was assessed by post-column analyte infusion and the mean extraction recovery was 95.6% across four quality control levels. The method is rugged and rapid with a total run time of 1.2 min and was applied to a bioequivalence study of 20 mg nifedipine tablet formulation in 30 healthy Indian subjects under fasting condition. Assay reproducibility was confirmed by reanalysis of 116 incurred samples.

  13. Eu(III)-Sensitized Luminescence Probe for Determination of Tolnaftate in Pharmaceuticals and Biological Fluids.

    Science.gov (United States)

    Alarfaj, Nawal A; El-Tohamy, Maha F

    2016-01-01

    A highly selective, sensitive, accurate, and reproducible luminescence procedure for determination of antifungal drug tolnaftate was developed. The introduced method was based on the formation of Europa Universalis III (Eu(III))-tolnaftate complex using sodium sulfite as a deoxygenated agent in the presence of acetate buffer (pH = 6) and micellar solution of anionic surfactant sodium dodecyl sulfate. The optimum conditions (effect of pH, buffer, surfactant, Eu(III), and sodium sulfite concentrations) for the luminescence signal were investigated and optimized. The luminescence signals were recorded at λex = 270 nm and λem = 460 nm. The method has a good linear response (0.2-130 μg/mL(-1)) between the luminescence intensity and the concentrations of the drug (r = 0.999), with a LOD 0.07 μg/mL(-1) and LOQ 0.2 μg/mL(-1). The luminescence signals of Eu (III)-tolnaftate-sodium dodecyl sulfate were found to be 200-fold more sensitive without the presence of micelle solution. The interferences of some additives, metals, amino acids, sugars, and other related pharmacological action drugs were examined and no interference was recorded. The proposed method was used for quick and simple determination of tolnaftate in its pharmaceuticals and biological fluids.

  14. Sensitive determination of carbendazim in orange juice by electrode modified with hybrid material.

    Science.gov (United States)

    Razzino, Claudia A; Sgobbi, Lívia F; Canevari, Thiago C; Cancino, Juliana; Machado, Sergio A S

    2015-03-01

    This paper describes the application of a glassy carbon electrode modified with a thin film of mesoporous silica/multiwalled carbon nanotubes for voltammetric determination of the fungicide carbendazim (CBZ). The hybrid material, (SiO2/MWCNT), was obtained by a sol-gel process using HF as the catalyst. The amperometric response to CBZ was measured at +0.73 V vs. Ag/AgCl by square wave voltammetry at pH 8.0. SiO2/MWCNT/GCE responded to CBZ in the linear range from 0.2 to 4.0 μmol L(-1). The calculated detection limit was 0.056 μmol L(-1), obtained using statistical methods. The SiO2/MWCNT/GCE sensor presented as the main characteristics high sensitivity, low detection limit and robustness, allowing CBZ determination in untreated real samples. In addition, this strategy afforded remarkable selectivity for CBZ against ascorbic and citric acid which are the main compounds of the orange juice. The excellent sensitivity and selectivity yielded feasible application for CBZ detection in orange juice sample.

  15. [Enzyme biosensors for penicillin determination based on conductometric planar electrodes and pH-sensitive field effect transistor].

    Science.gov (United States)

    Arkhipova, V N; Dziadevich, S V; Soldatkin, A P; El'skaia, A V

    1996-01-01

    The enzyme biosensors for penicillin determination based on conductometric planar electrodes and pH-sensitive field effect transistors have been described and their working parameters have been compared. The influence of pH, buffer capacity and ionic strength of the samples on the biosensors response has been studied. Short response time and high operational stability are characteristics of the developed biosensors.

  16. Development of High Sensitivity Nuclear Emulsion and Fine Grained Emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Kawahara, H.; Asada, T. [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Naka, T. [Institute of Advanced Research, Nagoya University (Japan); Naganawa, N.; Kuwabara, K.; Nakamura, M. [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

    2014-08-15

    Nuclear emulsion is a particle detector having high spacial resolution and angular resolution. It became useful for large statistics experiment thanks to the development of automatic scanning system. In 2010, a facility for emulsion production was introduced and R and D of nuclear emulsion began at Nagoya university. In this paper, we present results of development of the high sensitivity emulsion and fine grained emulsion for dark matter search experiment. Improvement of sensitivity is achieved by raising density of silver halide crystals and doping well-adjusted amount of chemicals. Production of fine grained emulsion was difficult because of unexpected crystal condensation. By mixing polyvinyl alcohol (PVA) to gelatin as a binder, we succeeded in making a stable fine grained emulsion.

  17. Highly sensitive troponin T in patients with acute ischemic stroke

    DEFF Research Database (Denmark)

    Jensen, J K; Ueland, T; Aukrust, P;

    2012-01-01

    in decedents than in survivors. After adjustment for stroke severity, C-reactive protein, age, NT-proBNP and prior heart and/or renal failure, hsTnT levels were not a significant predictor of long-term all-cause or cardiovascular mortality. Conclusion: Elevated levels of hsTnT are frequently present......Background: Newly developed troponin assays have superior diagnostic and prognostic performance in acute coronary syndrome (ACS), when compared to conventional troponin assays; however, highly sensitive troponin has not been evaluated in patients with acute ischemic stroke. Methods: Highly...... sensitive troponin T (hsTnT) was measured daily during the first 4 days in 193 consecutive patients with acute ischemic stroke without overt ACS or atrial fibrillation. The patients were previously tested normal with a fourth-generation TnT assay. The patients were followed for 47 months, with all...

  18. Structural Glycomic Analyses at High Sensitivity: A Decade of Progress

    Science.gov (United States)

    Alley, William R.; Novotny, Milos V.

    2013-06-01

    The field of glycomics has recently advanced in response to the urgent need for structural characterization and quantification of complex carbohydrates in biologically and medically important applications. The recent success of analytical glycobiology at high sensitivity reflects numerous advances in biomolecular mass spectrometry and its instrumentation, capillary and microchip separation techniques, and microchemical manipulations of carbohydrate reactivity. The multimethodological approach appears to be necessary to gain an in-depth understanding of very complex glycomes in different biological systems.

  19. Highly Sensitive Flexible Magnetic Sensor Based on Anisotropic Magnetoresistance Effect.

    Science.gov (United States)

    Wang, Zhiguang; Wang, Xinjun; Li, Menghui; Gao, Yuan; Hu, Zhongqiang; Nan, Tianxiang; Liang, Xianfeng; Chen, Huaihao; Yang, Jia; Cash, Syd; Sun, Nian-Xiang

    2016-11-01

    A highly sensitive flexible magnetic sensor based on the anisotropic magnetoresistance effect is fabricated. A limit of detection of 150 nT is observed and excellent deformation stability is achieved after wrapping of the flexible sensor, with bending radii down to 5 mm. The flexible AMR sensor is used to read a magnetic pattern with a thickness of 10 μm that is formed by ferrite magnetic inks.

  20. High-sensitivity Cardiac Troponin Elevation after Electroconvulsive Therapy: A Prospective, Observational Cohort Study.

    Science.gov (United States)

    Duma, Andreas; Pal, Swatilika; Johnston, Joshua; Helwani, Mohammad A; Bhat, Adithya; Gill, Bali; Rosenkvist, Jessica; Cartmill, Christopher; Brown, Frank; Miller, J Philip; Scott, Mitchell G; Sanchez-Conde, Francisco; Jarvis, Michael; Farber, Nuri B; Zorumski, Charles F; Conway, Charles; Nagele, Peter

    2017-04-01

    While electroconvulsive therapy is widely regarded as a lifesaving and safe procedure, evidence regarding its effects on myocardial cell injury is sparse. The objective of this investigation was to determine the incidence and magnitude of new cardiac troponin elevation after electroconvulsive therapy using a novel high-sensitivity cardiac troponin I assay. This was a prospective cohort study in adult patients undergoing electroconvulsive therapy in a single academic center (up to three electroconvulsive therapy treatments per patient). The primary outcome was new high-sensitivity cardiac troponin I elevation after electroconvulsive therapy, defined as an increase of high-sensitivity cardiac troponin I greater than 100% after electroconvulsive therapy compared to baseline with at least one value above the limit of quantification (10 ng/l). Twelve-lead electrocardiogram and high-sensitivity cardiac troponin I values were obtained before and 15 to 30 min after electroconvulsive therapy; in a subset of patients, an additional 2-h high-sensitivity cardiac troponin I value was obtained. The final study population was 100 patients and a total of 245 electroconvulsive therapy treatment sessions. Eight patients (8 of 100; 8%) experienced new high-sensitivity cardiac troponin I elevation after electroconvulsive therapy with a cumulative incidence of 3.7% (9 of 245 treatments; one patient had two high-sensitivity cardiac troponin I elevations), two of whom had a non-ST-elevation myocardial infarction (incidence 2 of 245; 0.8%). Median high-sensitivity cardiac troponin I concentrations did not increase significantly after electroconvulsive therapy. Tachycardia and/or elevated systolic blood pressure developed after approximately two thirds of electroconvulsive therapy treatments. Electroconvulsive therapy appears safe from a cardiac standpoint in a large majority of patients. A small subset of patients with preexisting cardiovascular risk factors, however, may develop new

  1. High sensitivity of quick view capsule endoscopy for detection of small bowel Crohn's disease

    DEFF Research Database (Denmark)

    Halling, Morten Lee; Nathan, Torben; Kjeldsen, Jens

    2014-01-01

    Capsule endoscopy (CE) has a high sensitivity for diagnosing small bowel Crohn's disease, but video analysis is time consuming. The quick view (qv) function is an effective tool to reduce time consumption. The aim of this study was to determine the rate of missed small bowel ulcerations with qv...

  2. Recent trends in high spin sensitivity magnetic resonance

    Science.gov (United States)

    Blank, Aharon; Twig, Ygal; Ishay, Yakir

    2017-07-01

    new ideas, show how these limiting factors can be mitigated to significantly improve the sensitivity of induction detection. Finally, we outline some directions for the possible applications of high-sensitivity induction detection in the field of electron spin resonance.

  3. Pulsed Discharge Helium Ionization Detector for Highly Sensitive Aquametry.

    Science.gov (United States)

    Mowry, Curtis D; Pimentel, Adam S; Sparks, Elizabeth S; Moorman, Matthew W; Achyuthan, Komandoor E; Manginell, Ronald P

    2016-01-01

    Trace moisture quantitation is crucial in medical, civilian and military applications. Current aquametry technologies are limited by the sample volume, reactivity, or interferences, and/or instrument size, weight, power, cost, and complexity. We report for the first time on the use of a pulsed discharge helium ionization detector (PDHID-D2) (∼196 cm(3)) for the sensitive (limit of detection, 0.047 ng; 26 ppm), linear (r(2) >0.99), and rapid (volume of liquid or gas. The relative humidity sensitivity was 0.22% (61.4 ppmv) with a limit of detection of less than 1 ng moisture with gaseous samples. The sensitivity was 10 to 100 to fold superior to competing technologies without the disadvantages inherent to these technologies. The PDHID-D2, due to its small footprint and low power requirement, has good size, weight, and power-portability (SWAPP) factors. The relatively low cost (∼$5000) and commercial availability of the PDHID-D2 makes our technique applicable to highly sensitive aquametry.

  4. Thyroid hormone determines the start of the sensitive period of imprinting and primes later learning.

    Science.gov (United States)

    Yamaguchi, Shinji; Aoki, Naoya; Kitajima, Takaaki; Iikubo, Eiji; Katagiri, Sachiko; Matsushima, Toshiya; Homma, Koichi J

    2012-01-01

    Filial imprinting in precocial birds is the process of forming a social attachment during a sensitive or critical period, restricted to the first few days after hatching. Imprinting is considered to be part of early learning to aid the survival of juveniles by securing maternal care. Here we show that the thyroid hormone 3,5,3'-triiodothyronine (T(3)) determines the start of the sensitive period. Imprinting training in chicks causes rapid inflow of T(3), converted from circulating plasma thyroxine by Dio2, type 2 iodothyronine deiodinase, in brain vascular endothelial cells. The T(3) thus initiates and extends the sensitive period to last more than 1 week via non-genomic mechanisms and primes subsequent learning. Even in non-imprinted chicks whose sensitive period has ended, exogenous T(3) enables imprinting. Our findings indicate that T(3) determines the start of the sensitive period for imprinting and has a critical role in later learning.

  5. Determination of Crosslinking in High Tg Polymers

    Science.gov (United States)

    1980-07-01

    microgels . The authors claim this type of reaction to be more typical of crosslinking chain polymerizations where, at higher contents of crosslinking...that the decisive factor determining the morphology of cured epoxy resins is given by the number of microgel particles formed during the very early...stages of the curing process. According to these authors the onset of crosslinking occurs localized with the formation of microgel particles of high

  6. Performance of terahertz metamaterials as high-sensitivity sensor

    Science.gov (United States)

    He, Yanan; Zhang, Bo; Shen, Jingling

    2017-09-01

    A high-sensitivity sensor based on the resonant transmission characteristics of terahertz (THz) metamaterials was investigated, with the proposal and fabrication of rectangular bar arrays of THz metamaterials exhibiting a period of 180 μm on a 25 μm thick flexible polyimide. Varying the size of the metamaterial structure revealed that the length of the rectangular unit modulated the resonant frequency, which was verified by both experiment and simulation. The sensing characteristics upon varying the surrounding media in the sample were tested by simulation and experiment. Changing the surrounding medium from that of air to that of alcohol or oil produced resonant frequency redshifts of 80 GHz or 150 GHz, respectively, which indicates that the sensor possessed a high sensitivity of 667 GHz per unit of refractive index. Finally, the influence of the sample substrate thickness on the sensor sensitivity was investigated by simulation. It may be a reference for future sensor design.

  7. High-sensitivity strain visualization using electroluminescence technologies

    Science.gov (United States)

    Xu, Jian; Jo, Hongki

    2016-04-01

    Visualizing mechanical strain/stress changes is an emerging area in structural health monitoring. Several ways are available for strain change visualization through the color/brightness change of the materials subjected to the mechanical stresses, for example, using mechanoluminescence (ML) materials and mechanoresponsive polymers (MRP). However, these approaches were not effectively applicable for civil engineering system yet, due to insufficient sensitivity to low-level strain of typical civil structures and limitation in measuring both static and dynamic strain. In this study, design and validation for high-sensitivity strain visualization using electroluminescence technologies are presented. A high-sensitivity Wheatstone bridge, of which bridge balance is precisely controllable circuits, is used with a gain-adjustable amplifier. The monochrome electroluminescence (EL) technology is employed to convert both static and dynamic strain change into brightness/color change of the EL materials, through either brightness change mode (BCM) or color alternation mode (CAM). A prototype has been made and calibrated in lab, the linearity between strain and brightness change has been investigated.

  8. High-sensitive scanning laser magneto-optical imaging system.

    Science.gov (United States)

    Murakami, Hironaru; Tonouchi, Masayoshi

    2010-01-01

    A high-sensitive scanning laser magneto-optical (MO) imaging system has been developed. The system is mainly composed of a laser source, galvano meters, and a high-sensitive differential optical-detector. Preliminary evaluation of system performance by using a Faraday indicator with a Faraday rotation coefficient of 3.47 x 10(-5) rad/microm Oe shows a magnetic sensitivity of about 5 microT, without any need for accumulation or averaging processing. Using the developed MO system we have succeeded in the fast and quantitative imaging of a rotationally symmetric magnetic field distribution around an YBa(2)Cu(3)O(7-delta) (YBCO) strip line applied with dc-biased current, and also succeeded in the detection of quantized fine signals corresponding to magnetic flux quantum generation in a superconducting loop of an YBCO Josephson vortex flow transistor. Thus, the developed system enables us not only to do fast imaging and local signal detection but also to directly evaluate both the strength and direction of a magnetic signal.

  9. HIGHLY SENSITIVE CATALASE ELECTRODE BASED ON POLYPYRROLE FILMS WITH MICROCONTAINERS

    Institute of Scientific and Technical Information of China (English)

    Yu-ying Gao; Gao-quan Shi

    2006-01-01

    Highly sensitive catalase electrodes for sensing hydrogen peroxide have been fabricated based on polypyrrole films with microcontainers. The microcontainers have a cup-like morphology and are arranged in a density of 4000 units cm-2.Catalase was immobilized into the polypyrrole films with microcontainers (Ppy-mc), which were coated on a Pt substrate electrode. The catalase/Ppy-mc/Pt electrode showed linear response to hydrogen peroxide in the range of 0-18 mmol/L at a potential of -0.3 V (versus SCE). Its sensitivity was measured to be approximately 3.64 μA (mmol/L)-1 cm-2, which is about two times that of the electrode fabricated from a flat Ppy film (catalase/Ppy-flat/Pt electrode). The electrode is highly selective for hydrogen peroxide and its sensitivity is interfered by potential interferents such as ascorbic acid, urea and fructose. Furthermore, such catalase electrodes showed long-term storage stability of 15 days under dry conditions at 4℃.

  10. Antibody desensitization therapy in highly sensitized lung transplant candidates.

    Science.gov (United States)

    Snyder, L D; Gray, A L; Reynolds, J M; Arepally, G M; Bedoya, A; Hartwig, M G; Davis, R D; Lopes, K E; Wegner, W E; Chen, D F; Palmer, S M

    2014-04-01

    As HLAs antibody detection technology has evolved, there is now detailed HLA antibody information available on prospective transplant recipients. Determining single antigen antibody specificity allows for a calculated panel reactive antibodies (cPRA) value, providing an estimate of the effective donor pool. For broadly sensitized lung transplant candidates (cPRA ≥ 80%), our center adopted a pretransplant multi-modal desensitization protocol in an effort to decrease the cPRA and expand the donor pool. This desensitization protocol included plasmapheresis, solumedrol, bortezomib and rituximab given in combination over 19 days followed by intravenous immunoglobulin. Eight of 18 candidates completed therapy with the primary reasons for early discontinuation being transplant (by avoiding unacceptable antigens) or thrombocytopenia. In a mixed-model analysis, there were no significant changes in PRA or cPRA changes over time with the protocol. A sub-analysis of the median fluorescence intensity (MFI) change indicated a small decline that was significant in antibodies with MFI 5000-10,000. Nine of 18 candidates subsequently had a transplant. Posttransplant survival in these nine recipients was comparable to other pretransplant-sensitized recipients who did not receive therapy. In summary, an aggressive multi-modal desensitization protocol does not significantly reduce pretransplant HLA antibodies in a broadly sensitized lung transplant candidate cohort. © Copyright 2014 The American Society of Transplantation and the American Society of Transplant Surgeons.

  11. A sensitive post-column photochemical derivatization/fluorimetric detection system for HPLC determination of bisphosphonates.

    Science.gov (United States)

    Pérez-Ruiz, Tomás; Martínez-Lozano, Carmen; García-Martínez, María Dolores

    2009-02-27

    A new reversed-phase ion-pair high-performance liquid chromatographic (HPLC) method has been developed for the determination of the following bisphosphonic acids: alendronic acid (ALEN), etidronic acid (ETID), ibandronic acid (IBAN) and risedronic acid (RISE). Separation was achieved on a C(18) column using a mixture of 50 mmol L(-1) borate buffer pH 9.0 containing 0.25 mmol L(-1) tetrabutylammonium chloride and 0.5 mmol L(-1) EDTA and acetonitrile (97:3) as the mobile phase. The sensitive detection of the above bisphosphonic acids was based on their oxidation to orthophosphate by the on-line peroxydisulfate-assisted photolysis followed by post-column reaction with molybdate to yield phosphomolybdate. This subsequently reacted with thiamine to generate thiochrome and, finally, the fluorescence of thiochrome was measured at 440 nm with excitation at 375 nm. The developed method is precise with a mean relative standard deviation of 1.3%, sensitive (with a detection limit at the nmol L(-1) level), accurate, specific, rapid (analysis time approximately 13 min) and inexpensive because to the low cost of the reagents. The assay was applied to the analysis of the four bisphosphonic acids in commercial dosage formulations, in which the excipients did not interfere with the determination. The method was also applied to the determination of etidronate, risedronate and ibandronate in human urine. Sample preparation involves precipitation of the analytes from urine along with endogenous phosphates such as calcium salts by addition of calcium chloride at alkaline pH and dissolution of the precipitate in 0.05 mol L(-1) ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid.

  12. Determination of flavonoids in pharmaceutical preparations using Terbium sensitized fluorescence method

    Directory of Open Access Journals (Sweden)

    M Shaghaghi

    2009-12-01

    Full Text Available "nBackground and the Purpose of the Study: The aim of this study was development and validation of a simple, rapid and sensitive spectrofluorimetric method for determination of total flavonoids in two topical formulations of Calendula officinalis, Ziziphus Spina-christi and an oral drop of Hypiran perforatum L. The proposed method is based on the formation of terbium (Tb3+ "n-flavonoids (quercetin as a reference standard complex at pH 7.0, which has fluorescence intensely with maximum emission at 545 nm when excited at 310 nm. "nMethod "n: For ointments masses of topical formulations were weighed and added to ethanol-aqueous buffer (pH 10.0 and the resulting mixtures were shaken and then two phases were separated by centrifugation. Aqueous phases were filtered and then diluted with water. For Hypiran drops an appropriate portion was diluted with ethanol and then aliquots of sample or standard solutions were determined according to the experimental procedure. "nResults "n: Under the optimum conditions, total concentrations of flavonoids (as quercetin equivalent in three tested formulations were found to be 0.204 mg/g (for Dermatin cream, 0.476 mg/g (for Calendula ointment and 13.50 μg/ml (for Hypiran drops. Analytical recoveries from samples spiked with different amounts of quercetin were 96.1-104.0 % with RSD % of less than 3.5. Conclusion : The proposed method which requires a simple dissolution step without any matrix interferences provided high sensitivity and selectivity and was easily applied to determine total flavonoids in real samples of three investigated formulations with excellent reproducibility.

  13. Development of highly sensitive monolithic interferometer for infrared planet search

    Directory of Open Access Journals (Sweden)

    Jiang P.

    2011-07-01

    Full Text Available We present the design, fabrication and testing of a highly sensitive monolithic interferometer for InfraRed Exoplanet Tracker (IR-ET. This interferometer is field-compensated, thermal-stable for working in the wavelength range between 0.8 and 1.35 μm. Two arms of the interferometer creates a fixed delay of 18.0 mm, which is optimized to have the best sensitivity for radial velocity measurements of slow-rotating M dwarfs for planet detection. IR-ET is aiming to reach 3–20 m/s Doppler precision for J<10 M dwarfs in less than 15 min exposures. We plan to conduct a planet survey around hundreds of nearby M dwarfs through collaborations with Astrophysical Research Consortium scientists in 2011–2014.

  14. Polymer-Particle Pressure-Sensitive Paint with High Photostability

    Directory of Open Access Journals (Sweden)

    Yu Matsuda

    2016-04-01

    Full Text Available We propose a novel fast-responding and paintable pressure-sensitive paint (PSP based on polymer particles, i.e. polymer-particle (pp-PSP. As a fast-responding PSP, polymer-ceramic (PC-PSP is widely studied. Since PC-PSP generally consists of titanium (IV oxide (TiO2 particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of TiO2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP.

  15. New application of superconductors: high sensitivity cryogenic light detectors

    CERN Document Server

    Cardani, L; Casali, N; Casellano, M G; Colantoni, I; Coppolecchia, A; Cosmelli, C; Cruciani, A; D'Addabbo, A; Di Domizio, S; Martinez, M; Tomei, C; Vignati, M

    2016-01-01

    In this paper we describe the current status of the CALDER project, which is developing ultra-sensitive light detectors based on superconductors for cryogenic applications. When we apply an AC current to a superconductor, the Cooper pairs oscillate and acquire kinetic inductance, that can be measured by inserting the superconductor in a LC circuit with high merit factor. Interactions in the superconductor can break the Cooper pairs, causing sizable variations in the kinetic inductance and, thus, in the response of the LC circuit. The continuous monitoring of the amplitude and frequency modulation allows to reconstruct the incident energy with excellent sensitivity. This concept is at the basis of Kinetic Inductance Detectors (KIDs), that are characterized by natural aptitude to multiplexed read-out (several sensors can be tuned to different resonant frequencies and coupled to the same line), resolution of few eV, stable behavior over a wide temperature range, and ease in fabrication. We present the results ob...

  16. Significance of application of high-sensitive HBsAg ELISA kits in qualified blood donors determined by routine screening tests%超敏HBsAg ELISA检测试剂在常规检测合格的献血者中应用的意义

    Institute of Scientific and Technical Information of China (English)

    桑列勇; 傅立强; 庄培芬; 方放

    2011-01-01

    Objective;To assess the significance of the application of high - sensitive HBsAag ELISA kits in qualified blood donors determined by routine screening tests. Methods: HBsAg was determined in 8692 blood donors by one imported high - sensitive ELISA kit and two domestical produced ELISA kits, respectively. The results were further confirmed by three nested - PCRs specific for different regions in HBV - DNA and other serologic markers of HBV. Results; 48 out of 8692 blood donors were HBsAg positive. Among them, 32 were detected by Hepanostika? HBsAg ELBA kit, 22 by InTec PRODUCTS kit and 14 by Kehua Bio - engineering kit. The "a" epitope was detected in 40 out of 8692 samples by HBV - DNA analysis. Among those, 13 were determined as HBsAg positive and 8 negative by all three ELISA kits. In another 8 samples, HBsAg could be detected only by high - sensitive Hepanostika? HBsAg ELISA kit. Conclusion: Although the application of high - sensitive HBsAg ELISA kit can significantly decrease the risk of HBV infection in blood transfusion, the possibility of missing detection still remains. Therefore, the current strategy should focus on increasing the sensitivity of ELISA kit and promoting the use of DNA analysis technology. The combination of ELISA determination and DNA analysis can profoundly ensure the safety of blood transfusion.%目的:探讨在无偿献血HBsAg筛查中使用超敏HBsAg ELISA的意义.方法:使用一种进口超敏HBsAg试剂和两种国产HBsAg试剂对8692例无偿献血标本进行平行检测,并使用不同区域的三套巢式PCR和检测乙肝三系其他指标对HBsAg结果进行验证.结果:8692例标本中共检测出HBsAg阳性48例,其中Hepanostika HBsAg ELISA试剂32例,英科新创HBsAg ELISA试剂22例,科华HBsAg ELISA试剂14例,对8692例标本进行HBV-DNA测定,有40例获得a表位基因,其中13例为三种HBsAg ELISA试剂检测均阳性,8例为三种HBsAg ELISA试剂检测均阴性,8例为Hepanostika.HBsAg ELISA试剂检测

  17. Highly sensitive detection of urinary cadmium to assess personal exposure

    Energy Technology Data Exchange (ETDEWEB)

    Argun, Avni A.; Banks, Ashley M.; Merlen, Gwendolynne; Tempelman, Linda A. [Giner, Inc., 89 Rumford Ave., Newton 02466, MA United States (United States); Becker, Michael F.; Schuelke, Thomas [Fraunhofer USA – CCL, 1449 Engineering Research Ct., East Lansing 48824, MI (United States); Dweik, Badawi M., E-mail: bdweik@ginerinc.com [Giner, Inc., 89 Rumford Ave., Newton 02466, MA United States (United States)

    2013-04-22

    Highlights: ► An electrochemical sensor capable of detecting cadmium at parts-per-billion levels in urine. ► A novel fabrication method for Boron-Doped Diamond (BDD) ultramicroelectrode (UME) arrays. ► Unique combination of BDD UME arrays and a differential pulse voltammetry algorithm. ► High sensitivity, high reproducibility, and very low noise levels. ► Opportunity for portable operation to assess on-site personal exposure. -- Abstract: A series of Boron-Doped Diamond (BDD) ultramicroelectrode arrays were fabricated and investigated for their performance as electrochemical sensors to detect trace level metals such as cadmium. The steady-state diffusion behavior of these sensors was validated using cyclic voltammetry followed by electrochemical detection of cadmium in water and in human urine to demonstrate high sensitivity (>200 μA ppb{sup −1} cm{sup −2}) and low background current (<4 nA). When an array of ultramicroelectrodes was positioned with optimal spacing, these BDD sensors showed a sigmoidal diffusion behavior. They also demonstrated high accuracy with linear dose dependence for quantification of cadmium in a certified reference river water sample from the U.S. National Institute of Standards and Technology (NIST) as well as in a human urine sample spiked with 0.25–1 ppb cadmium.

  18. [Highly sensitive detection technology for biological toxins applying sugar epitopes].

    Science.gov (United States)

    Uzawa, Hirotaka

    2009-01-01

    The Shiga toxin is a highly poisonous protein produced by enterohemorrhagic Escherichia coli O157. This bacterial toxin causes the hemolytic uremic syndrome. Another plant toxin from castor beans, ricin, is also highly toxic. The toxin was used for assassination in London. Recently, there were several cases of postal matter containing ricin. Both toxins are categorized as biological warfare agents by the Centers of Disease Control and Prevention. Conventional detection methods based on the antigen-antibody reaction, PCR and other cell-free assays have been proposed. However, those approaches have drawbacks in terms of sensitivity, analytical time, or stability of the detection reagents. Therefore, development of a facile and sensitive detection method is essential. Here we describe new detection methods applying carbohydrate epitopes as the toxin ligands, which is based on the fact that the toxins bind cell-surface oligosaccharides. Namely, the Shiga toxin has an affinity for globobiosyl (Gb(2)) disaccharide, and ricin binds the beta-D-galactose residue. For Shiga toxin detection, surface plasmon resonance (SPR) was applied. A polyanionic Gb(2)-glycopolymer was designed for this purpose, and it was used for the assembly of Gb(2)-chips using alternating layer-by-layer technology. The method allowed us to detect the toxin at a low concentration of LD(50). A synthetic carbohydrate ligand for ricin was designed and immobilized on the chips. SPR analysis with the chips allows us to detect ricin in a highly sensitive and facile manner (10 pg/ml, 5 min). Our present approaches provide a highly effective way to counter bioterrorism.

  19. Baroreflex sensitivity as a determinant of responses to hydralazine in dogs.

    Science.gov (United States)

    Vidrio, H

    1983-01-01

    In order to evaluate the relation between hypotension induced by hydralazine and the resultant reflex tachycardia, as well as the role of baroreflex sensitivity in determining the magnitude of these responses, the drug was administered orally at a dose of 1 mg/kg to a group of trained conscious normotensive and renal hypertensive dogs. Responses were assessed by measuring blood pressure and heart rate for 8 hr after dosing and integrating the changes observed over time in order to obtain a mean value. Baroreflex gain was calculated as the ratio of heart rate to blood pressure responses. Hypotension was greater in hypertensives, whereas tachycardia was not different between groups. Gain was therefore smaller in hypertensives, but not uniformly so, a portion of these animals having values within the normotensive range. This high gain group responded with less hypotension and more tachycardia than did the low gain group. Differences in pressure and rate responses to repeated administration of hydralazine between the two groups were minimal. It is suggested that baroreflex gain, an innate individual characteristic, is an important determinant of acute pressure responses to hydralazine in dogs, hypertensive animals having less gain than normotensives and showing increased hypotensive responses. Gain appears not to be as important in determining the chronic effects of the drug.

  20. Detecting determinism with improved sensitivity in time series: Rank-based nonlinear predictability score

    Science.gov (United States)

    Naro, Daniel; Rummel, Christian; Schindler, Kaspar; Andrzejak, Ralph G.

    2014-09-01

    The rank-based nonlinear predictability score was recently introduced as a test for determinism in point processes. We here adapt this measure to time series sampled from time-continuous flows. We use noisy Lorenz signals to compare this approach against a classical amplitude-based nonlinear prediction error. Both measures show an almost identical robustness against Gaussian white noise. In contrast, when the amplitude distribution of the noise has a narrower central peak and heavier tails than the normal distribution, the rank-based nonlinear predictability score outperforms the amplitude-based nonlinear prediction error. For this type of noise, the nonlinear predictability score has a higher sensitivity for deterministic structure in noisy signals. It also yields a higher statistical power in a surrogate test of the null hypothesis of linear stochastic correlated signals. We show the high relevance of this improved performance in an application to electroencephalographic (EEG) recordings from epilepsy patients. Here the nonlinear predictability score again appears of higher sensitivity to nonrandomness. Importantly, it yields an improved contrast between signals recorded from brain areas where the first ictal EEG signal changes were detected (focal EEG signals) versus signals recorded from brain areas that were not involved at seizure onset (nonfocal EEG signals).

  1. Ultrathin plasmonic nanogratings for rapid and highly-sensitive detection

    CERN Document Server

    Zeng, Beibei; Bartoli, Filbert J

    2014-01-01

    We developed a nanoplasmonic sensor platform employing the extraordinary optical properties of one-dimensional nanogratings patterned on 30nm-thick ultrathin Ag films. Excitation of Fano resonances in the ultrathin Ag nanogratings results in transmission spectra with high amplitude, large contrast, and narrow bandwidth, making them well-suited for rapid and highly-sensitive sensing applications. The ultrathin nanoplasmonic sensor chip was integrated with a polydimethylsiloxane (PDMS) microfluidic channel, and the measured refractive index resolution was found to be 1.46x10-6 refractive index units (RIU) with a high temporal resolution of 1 sec. This compares favorably with commercial prism-based surface plasmon resonance sensors, but is achieved using a more convenient collinear transmission geometry and a significantly smaller sensor footprint of 50x50um2. In addition, an order-of-magnitude improvement in the temporal and spatial resolutions was achieved relative to state-of-the-art nanoplasmonic sensors, fo...

  2. A kinetic clutch governs religation by type IB topoisomerases and determines camptothecin sensitivity.

    Science.gov (United States)

    Seol, Yeonee; Zhang, Hongliang; Pommier, Yves; Neuman, Keir C

    2012-10-02

    Type IB topoisomerases (Top1Bs) relax excessive DNA supercoiling associated with replication and transcription by catalyzing a transient nick in one strand to permit controlled rotation of the DNA about the intact strand. The natural compound camptothecin (CPT) and the cancer chemotherapeutics derived from it, irinotecan and topotecan, are highly specific inhibitors of human nuclear Top1B (nTop1). Previous work on vaccinia Top1B led to an elegant model that describes a straightforward dependence of rotation and religation on the torque caused by supercoiling. Here, we used a single-molecule DNA supercoil relaxation assay to measure the torque dependence of nTop1 and its inhibition by CPT. For comparison, we also examined mitochondrial Top1B and an N-terminal deletion mutant of nTop1. Despite substantial sequence homology in their core domains, nTop1 and mitochondrial Top1B exhibit dramatic differences in sensitivity to torque and CPT, with the N-terminal deletion mutant of nTop1 showing intermediate characteristics. In particular, nTop1 displays nearly torque-independent religation probability, distinguishing it from other Top1B enzymes studied to date. Kinetic modeling reveals a hitherto unobserved torque-independent transition linking the DNA rotation and religation phases of the enzymatic cycle. The parameters of this transition determine the torque sensitivity of religation and the efficiency of CPT binding. This "kinetic clutch" mechanism explains the molecular basis of CPT sensitivity and more generally provides a framework with which to interpret Top1B activity and inhibition.

  3. Progression of glomerular filtration rate reduction determined in conscious Dahl salt-sensitive hypertensive rats.

    Science.gov (United States)

    Cowley, Allen W; Ryan, Robert P; Kurth, Terry; Skelton, Meredith M; Schock-Kusch, Daniel; Gretz, Norbert

    2013-07-01

    Sequential changes in glomerular filtration rate during development of hypertension in the conscious Dahl salt-sensitive rats were determined using a new method for measurement. Using a miniaturized device, disappearance curves of fluorescein isothiocyanate-sinistrin were measured by transcutaneous excitation and real-time detection of the emitted light through the skin. Rats with implanted femoral venous catheters (dye injection and sampling) and carotid catheters (mean arterial pressure by telemetry) were studied, while maintained on a 0.4% NaCl diet and on days 2, 5, 7, 14, and 21 after switching to 4.0% (high-salt [HS]) diet. A separate group of rats were maintained on 0.4% for 21 days as a time control. Mean arterial pressure rose progressively from the last day of 0.4% (130±2 mm Hg) reaching significance by day 5 of HS and averaged 162±7 mm Hg by day 21. Urine albumin excretion was significantly elevated (×3) by day 7 of HS in Dahl salt-sensitive rats. Glomerular filtration rate reduced on day 14 of HS falling from 1.53±0.06 mL/min per 100 g body weight to 1.27±0.04. By day 21, glomerular filtration rate had fallen 28% to 1.1±0.04 mL/min per 100 g (t(1/2) 28.4±1.1 minute.) No significant reductions of creatinine clearance were observed throughout the study in response to HS demonstrating the insensitivity of creatinine clearance measurements even with creatinine measured using mass spectrometry. We conclude that the observed reduction of glomerular filtration rate was a consequence and not a cause of the hypertension and that this noninvasive approach could be used in these conscious Dahl salt-sensitive rats for a longitudinal assessment of renal function.

  4. Potential programs for high sensitivity FIR spectroscopy with SPICA

    CERN Document Server

    Spinoglio, L; Saraceno, P; Spinoglio, Luigi; Giorgio, Anna Maria Di; Saraceno, Paolo

    2006-01-01

    We discuss the potential of high sensitivity mid-IR and far-IR spectroscopy to proof the physical properties of active nuclei and starburst regions of local and distant galaxies. For local galaxies, it will be possible to map the discs and ISM through the low ionization ionic lines and a variety of molecular tracers, such as OH, H2O and high-J CO. At increasing distance, most of the ionic nebular lines (typical of stars and AGNs) are shifted into the FIR, making possible to compare the observed spectra with those predicted by different evolutionary scenarios. At the very high redshift of 10-15, sensitive mid-to-far-IR spectrometers, such as those planned to be at the focal plane of the future SPICA mision, could be adequate to detect the H recombination lines excited in the HII regions around population III stars, if these stars happened to reside in large clusters of more than 10^5 members.

  5. High-sensitivity piezoelectric perovskites for magnetoelectric composites

    Science.gov (United States)

    Amorín, Harvey; Algueró, Miguel; Campo, Rubén Del; Vila, Eladio; Ramos, Pablo; Dollé, Mickael; Romaguera-Barcelay, Yonny; Cruz, Javier Pérez De La; Castro, Alicia

    2015-01-01

    A highly topical set of perovskite oxides are high-sensitivity piezoelectric ones, among which Pb(Zr,Ti)O3 at the morphotropic phase boundary (MPB) between ferroelectric rhombohedral and tetragonal polymorphic phases is reckoned a case study. Piezoelectric ceramics are used in a wide range of mature, electromechanical transduction technologies like piezoelectric sensors, actuators and ultrasound generation, to name only a few examples, and more recently for demonstrating novel applications like magnetoelectric composites. In this case, piezoelectric perovskites are combined with magnetostrictive materials to provide magnetoelectricity as a product property of the piezoelectricity and piezomagnetism of the component phases. Interfaces play a key issue, for they control the mechanical coupling between the piezoresponsive phases. We present here main results of our investigation on the suitability of the high sensitivity MPB piezoelectric perovskite BiScO3–PbTiO3 in combination with ferrimagnetic spinel oxides for magnetoelectric composites. Emphasis has been put on the processing at low temperature to control reactions and interdiffusion between the two oxides. The role of the grain size effects is extensively addressed. PMID:27877758

  6. Immunoglobulin E sensitization to cross-reactive carbohydrate determinants: epidemiological study of clinical relevance and role of alcohol consumption

    DEFF Research Database (Denmark)

    Linneberg, Allan; Fenger, Runa Vavia; Husemoen, Lise-Lotte;

    2010-01-01

    The determinants and biologic significance of IgE-mediated sensitization to cross-reactive carbohydrate determinants (CCDs) are not entirely known. An association between alcohol consumption and CCD sensitization has been reported in studies from Spain and Portugal....

  7. High-Sensitivity Measurement of Density by Magnetic Levitation.

    Science.gov (United States)

    Nemiroski, Alex; Kumar, A A; Soh, Siowling; Harburg, Daniel V; Yu, Hai-Dong; Whitesides, George M

    2016-03-01

    This paper presents methods that use Magnetic Levitation (MagLev) to measure very small differences in density of solid diamagnetic objects suspended in a paramagnetic medium. Previous work in this field has shown that, while it is a convenient method, standard MagLev (i.e., where the direction of magnetization and gravitational force are parallel) cannot resolve differences in density mm) because (i) objects close in density prevent each other from reaching an equilibrium height due to hard contact and excluded volume, and (ii) using weaker magnets or reducing the magnetic susceptibility of the medium destabilizes the magnetic trap. The present work investigates the use of weak magnetic gradients parallel to the faces of the magnets as a means of increasing the sensitivity of MagLev without destabilization. Configuring the MagLev device in a rotated state (i.e., where the direction of magnetization and gravitational force are perpendicular) relative to the standard configuration enables simple measurements along the axes with the highest sensitivity to changes in density. Manipulating the distance of separation between the magnets or the lengths of the magnets (along the axis of measurement) enables the sensitivity to be tuned. These modifications enable an improvement in the resolution up to 100-fold over the standard configuration, and measurements with resolution down to 10(-6) g/cm(3). Three examples of characterizing the small differences in density among samples of materials having ostensibly indistinguishable densities-Nylon spheres, PMMA spheres, and drug spheres-demonstrate the applicability of rotated Maglev to measuring the density of small (0.1-1 mm) objects with high sensitivity. This capability will be useful in materials science, separations, and quality control of manufactured objects.

  8. High pressure-sensitive gene expression in Lactobacillus sanfranciscensis

    Directory of Open Access Journals (Sweden)

    R.F. Vogel

    2005-08-01

    Full Text Available Lactobacillus sanfranciscensis is a Gram-positive lactic acid bacterium used in food biotechnology. It is necessary to investigate many aspects of a model organism to elucidate mechanisms of stress response, to facilitate preparation, application and performance in food fermentation, to understand mechanisms of inactivation, and to identify novel tools for high pressure biotechnology. To investigate the mechanisms of the complex bacterial response to high pressure we have analyzed changes in the proteome and transcriptome by 2-D electrophoresis, and by microarrays and real time PCR, respectively. More than 16 proteins were found to be differentially expressed upon high pressure stress and were compared to those sensitive to other stresses. Except for one apparently high pressure-specific stress protein, no pressure-specific stress proteins were found, and the proteome response to pressure was found to differ from that induced by other stresses. Selected pressure-sensitive proteins were partially sequenced and their genes were identified by reverse genetics. In a transcriptome analysis of a redundancy cleared shot gun library, about 7% of the genes investigated were found to be affected. Most of them appeared to be up-regulated 2- to 4-fold and these results were confirmed by real time PCR. Gene induction was shown for some genes up-regulated at the proteome level (clpL/groEL/rbsK, while the response of others to high hydrostatic pressure at the transcriptome level seemed to differ from that observed at the proteome level. The up-regulation of selected genes supports the view that the cell tries to compensate for pressure-induced impairment of translation and membrane transport.

  9. High Sensitivity Optomechanical Reference Accelerometer over 10 kHz

    Science.gov (United States)

    2014-06-05

    characterizing fast mechanical dynamics and piezo -electric devices, but typically not both. Yet extremely high resolution maintained over large...applying a ringdown technique in vacuum. To this end, we used a piezo -shaker to excite the oscillator at its resonance frequency and measured the...exponential decay response. The resonance peak was determined by spectral analysis and then honed in by a high resolution function generator driving the piezo

  10. Determining importance weighting functions for Contributon theory eigenvalue sensitivity coefficient methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Perfetti, C.; Martin, W. [Univ. of Michigan, Dept. of Nuclear Engineering and Radiological Sciences, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109-2104 (United States); Rearden, B.; Williams, M. [Oak Ridge National Laboratory, Reactor and Nuclear Systems Div., Bldg. 5700, P.O. Box 2008, Oak Ridge, TN 37831-6170 (United States)

    2012-07-01

    This study introduced two new approaches for calculating the F*(r) importance weighting function for Contributon and CLUTCH eigenvalue sensitivity coefficient calculations, and compared them in terms of accuracy and applicability. The necessary levels of F*(r) mesh refinement and mesh convergence for obtaining accurate eigenvalue sensitivity coefficients were determined for two preliminary problems through two parametric studies, and the results of these studies suggest that a sufficiently accurate F*(r) mesh for calculating eigenvalue sensitivity coefficients can be obtained for these problems with only a small increase in problem runtime. (authors)

  11. Determining Importance Weighting Functions for Contributon Theory Eigenvalue Sensitivity Coefficient Methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Perfetti, Christopher M [ORNL; Martin, William R [University of Michigan; Rearden, Bradley T [ORNL; Williams, Mark L [ORNL

    2012-01-01

    This study introduced three approaches for calculating the importance weighting function for Contributon and CLUTCH eigenvalue sensitivity coefficient calculations, and compared them in terms of accuracy and applicability. The necessary levels of mesh refinement and mesh convergence for obtaining accurate eigenvalue sensitivity coefficients were determined through two parametric studies, and the results of these studies suggest that a sufficiently-accurate mesh for calculating eigenvalue sensitivity coefficients can be obtained for the Contributon and CLUTCH methods with only a small increase in problem runtime.

  12. Rituximab induction therapy in highly sensitized kidney transplant recipients

    Institute of Scientific and Technical Information of China (English)

    YIN Hang; WAN Hao; HU Xiao-peng; LI Xiao-bei; WANG Wei; LIU Hang; REN Liang; ZHANG Xiao-dong

    2011-01-01

    Background The number of highly sensitized patients is rising, and sensitization can lead to renal transplant failure.The present study aimed to investigate the safety and efficacy of renal transplantation following induction therapy with rituximab in highly sensitized kidney transplant recipients.Methods Seven highly sensitized kidney transplant recipients who underwent rituximab therapy from December 2008 to December 2009 were retrospectively analyzed. There were 3 men and 4 women, with a mean age of 38.5 years (range, 21-47 years). The duration of hemodialysis was 3-12 months, with a mean duration of 11 months. For 4 patients,this was the second transplant; the previous graft survival time was 2-11 years, with a mean survival time of 5.8 years. All the female recipients had history of multiple pregnancies, and all patients had previously received blood transfusions. All donors were men, with a mean age of 32.5 years (range, 25-37 years). In 2 of the 7 patients, both class I and class II of panel reactive antibody were high; the remaining 5 patients showed either high in class I or in class II of panel reactive antibody. The mean panel reactive antibody value was 31% for class I and 51% for class II respectively. The donors and the recipients had the same blood type, with low lymphocyte cytotoxicity ranging from 2% to 5%. The human leukocyte antigen (HLA) mismatch numbers were from 2 to 4. All patients received tacrolimus (0.1 mg·kg-1·d-1) and mycophenolate mofetil (750 mg twice per day) orally 3 days prior to surgery. All patients received a single dose of 600 mg rituximab (375 mg/m2) infusion on the day before surgery and polyclonal antibody (antithymocyte globulin) on the day of surgery.Postoperative creatinine, creatinine clearance rate, and occurrence of rejection by pathological biopsy confirmation were monitored.Results No patient had delayed graft function after surgery. Two patients had acute rejection, one on day 7 and the other on day 13 post

  13. Highly sensitive detection of Staphylococcus aureus directly from patient blood.

    Directory of Open Access Journals (Sweden)

    Padmapriya P Banada

    Full Text Available BACKGROUND: Rapid detection of bloodstream infections (BSIs can be lifesaving. We investigated the sample processing and assay parameters necessary for highly-sensitive detection of bloodstream bacteria, using Staphylococcus aureus as a model pathogen and an automated fluidic sample processing-polymerase chain reaction (PCR platform as a model diagnostic system. METHODOLOGY/PRINCIPAL FINDINGS: We compared a short 128 bp amplicon hemi-nested PCR and a relatively shorter 79 bp amplicon nested PCR targeting the S. aureus nuc and sodA genes, respectively. The sodA nested assay showed an enhanced limit of detection (LOD of 5 genomic copies per reaction or 10 colony forming units (CFU per ml blood over 50 copies per reaction or 50 CFU/ml for the nuc assay. To establish optimal extraction protocols, we investigated the relative abundance of the bacteria in different components of the blood (white blood cells (WBCs, plasma or whole blood, using the above assays. The blood samples were obtained from the patients who were culture positive for S. aureus. Whole blood resulted in maximum PCR positives with sodA assay (90% positive as opposed to cell-associated bacteria (in WBCs (71% samples positive or free bacterial DNA in plasma (62.5% samples positive. Both the assays were further tested for direct detection of S. aureus in patient whole blood samples that were contemporaneous culture positive. S. aureus was detected in 40/45 of culture-positive patients (sensitivity 89%, 95% CI 0.75-0.96 and 0/59 negative controls with the sodA assay (specificity 100%, 95% CI 0.92-1. CONCLUSIONS: We have demonstrated a highly sensitive two-hour assay for detection of sepsis causing bacteria like S. aureus directly in 1 ml of whole blood, without the need for blood culture.

  14. A novel high resolution, high sensitivity SPECT detector for molecular imaging of cardiovascular diseases

    Science.gov (United States)

    Cusanno, F.; Argentieri, A.; Baiocchi, M.; Colilli, S.; Cisbani, E.; De Vincentis, G.; Fratoni, R.; Garibaldi, F.; Giuliani, F.; Gricia, M.; Lucentini, M.; Magliozzi, M. L.; Majewski, S.; Marano, G.; Musico, P.; Musumeci, M.; Santavenere, F.; Torrioli, S.; Tsui, B. M. W.; Vitelli, L.; Wang, Y.

    2010-05-01

    Cardiovascular diseases are the most common cause of death in western countries. Understanding the rupture of vulnerable atherosclerotic plaques and monitoring the effect of innovative therapies of heart failure is of fundamental importance. A flexible, high resolution, high sensitivity detector system for molecular imaging with radionuclides on small animal models has been designed for this aim. A prototype has been built using tungsten pinhole and LaBr3(Ce) scintillator coupled to Hamamatsu Flat Panel PMTs. Compact individual-channel readout has been designed, built and tested. Measurements with phantoms as well as pilot studies on mice have been performed, the results show that the myocardial perfusion in mice can be determined with sufficient precision. The detector will be improved replacing the Hamamatsu Flat Panel with Silicon Photomultipliers (SiPMs) to allow integration of the system with MRI scanners. Application of LaBr3(Ce) scintillator coupled to photosensor with high photon detection efficiency and excellent energy resolution will allow dual-label imaging to monitor simultaneously the cardiac perfusion and the molecular targets under investigation during the heart therapy.

  15. Coumarin-bearing triarylamine sensitizers with high molar extinction coefficient for dye-sensitized solar cells

    Science.gov (United States)

    Zhong, Changjian; Gao, Jianrong; Cui, Yanhong; Li, Ting; Han, Liang

    2015-01-01

    Coumarin unit is introduced into triarylamine and three organic sensitizers are designed and synthesized with triarylamine bearing coumarin moiety as the electron donor, conjugated system containing thiophene unit as the π-bridge, and cyanoacetic acid moiety as the electron acceptor. The light-harvesting capabilities and photovoltaic performance of these dyes are investigated systematically with the comparison of different π-bridges. High molar extinction coefficients are observed in these triarylamine dyes and the photocurrent and photovoltage are increased with the introduction of another thiophene or benzene. Optimal photovoltaic performance (η = 6.24%, Voc = 690 mV, Jsc = 14.33 mA cm-2, and ff = 0.63) is observed in the DSSC based on dye with thiophene-phenyl unit as the π-conjugated bridge under 100 mW cm-2 simulated AM 1.5 G solar irradiation.

  16. Highly Sensitive Assay for Measurement of Arenavirus-cell Attachment.

    Science.gov (United States)

    Klaus, Joseph P; Botten, Jason

    2016-03-02

    Arenaviruses are a family of enveloped RNA viruses that cause severe human disease. The first step in the arenavirus life cycle is attachment of viral particles to host cells. While virus-cell attachment can be measured through the use of virions labeled with biotin, radioactive isotopes, or fluorescent dyes, these approaches typically require high multiplicities of infection (MOI) to enable detection of bound virus. We describe a quantitative (q)RT-PCR-based assay that measures Junin virus strain Candid 1 attachment via quantitation of virion-packaged viral genomic RNA. This assay has several advantages including its extreme sensitivity and ability to measure attachment over a large dynamic range of MOIs without the need to purify or label input virus. Importantly, this approach can be easily tailored for use with other viruses through the use of virus-specific qRT-PCR reagents. Further, this assay can be modified to permit measurement of particle endocytosis and genome uncoating. In conclusion, we describe a simple, yet robust assay for highly sensitive measurement of arenavirus-cell attachment.

  17. Sensitivity analysis for high accuracy proximity effect correction

    Science.gov (United States)

    Thrun, Xaver; Browning, Clyde; Choi, Kang-Hoon; Figueiro, Thiago; Hohle, Christoph; Saib, Mohamed; Schiavone, Patrick; Bartha, Johann W.

    2015-10-01

    A sensitivity analysis (SA) algorithm was developed and tested to comprehend the influences of different test pattern sets on the calibration of a point spread function (PSF) model with complementary approaches. Variance-based SA is the method of choice. It allows attributing the variance of the output of a model to the sum of variance of each input of the model and their correlated factors.1 The objective of this development is increasing the accuracy of the resolved PSF model in the complementary technique through the optimization of test pattern sets. Inscale® from Aselta Nanographics is used to prepare the various pattern sets and to check the consequences of development. Fraunhofer IPMS-CNT exposed the prepared data and observed those to visualize the link of sensitivities between the PSF parameters and the test pattern. First, the SA can assess the influence of test pattern sets for the determination of PSF parameters, such as which PSF parameter is affected on the employments of certain pattern. Secondly, throughout the evaluation, the SA enhances the precision of PSF through the optimization of test patterns. Finally, the developed algorithm is able to appraise what ranges of proximity effect correction is crucial on which portion of a real application pattern in the electron beam exposure.

  18. Correcting systematic errors in high-sensitivity deuteron polarization measurements

    Energy Technology Data Exchange (ETDEWEB)

    Brantjes, N.P.M. [Kernfysisch Versneller Instituut, University of Groningen, NL-9747AA Groningen (Netherlands); Dzordzhadze, V. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Gebel, R. [Institut fuer Kernphysik, Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Gonnella, F. [Physica Department of ' Tor Vergata' University, Rome (Italy); INFN-Sez. ' Roma tor Vergata,' Rome (Italy); Gray, F.E. [Regis University, Denver, CO 80221 (United States); Hoek, D.J. van der [Kernfysisch Versneller Instituut, University of Groningen, NL-9747AA Groningen (Netherlands); Imig, A. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Kruithof, W.L. [Kernfysisch Versneller Instituut, University of Groningen, NL-9747AA Groningen (Netherlands); Lazarus, D.M. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Lehrach, A.; Lorentz, B. [Institut fuer Kernphysik, Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Messi, R. [Physica Department of ' Tor Vergata' University, Rome (Italy); INFN-Sez. ' Roma tor Vergata,' Rome (Italy); Moricciani, D. [INFN-Sez. ' Roma tor Vergata,' Rome (Italy); Morse, W.M. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Noid, G.A. [Indiana University Cyclotron Facility, Bloomington, IN 47408 (United States); and others

    2012-02-01

    This paper reports deuteron vector and tensor beam polarization measurements taken to investigate the systematic variations due to geometric beam misalignments and high data rates. The experiments used the In-Beam Polarimeter at the KVI-Groningen and the EDDA detector at the Cooler Synchrotron COSY at Juelich. By measuring with very high statistical precision, the contributions that are second-order in the systematic errors become apparent. By calibrating the sensitivity of the polarimeter to such errors, it becomes possible to obtain information from the raw count rate values on the size of the errors and to use this information to correct the polarization measurements. During the experiment, it was possible to demonstrate that corrections were satisfactory at the level of 10{sup -5} for deliberately large errors. This may facilitate the real time observation of vector polarization changes smaller than 10{sup -6} in a search for an electric dipole moment using a storage ring.

  19. Mass Spectrometry-based Assay for High Throughput and High Sensitivity Biomarker Verification

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xuejiang; Tang, Keqi

    2017-06-14

    Searching for disease specific biomarkers has become a major undertaking in the biomedical research field as the effective diagnosis, prognosis and treatment of many complex human diseases are largely determined by the availability and the quality of the biomarkers. A successful biomarker as an indicator to a specific biological or pathological process is usually selected from a large group of candidates by a strict verification and validation process. To be clinically useful, the validated biomarkers must be detectable and quantifiable by the selected testing techniques in their related tissues or body fluids. Due to its easy accessibility, protein biomarkers would ideally be identified in blood plasma or serum. However, most disease related protein biomarkers in blood exist at very low concentrations (<1ng/mL) and are “masked” by many none significant species at orders of magnitude higher concentrations. The extreme requirements of measurement sensitivity, dynamic range and specificity make the method development extremely challenging. The current clinical protein biomarker measurement primarily relies on antibody based immunoassays, such as ELISA. Although the technique is sensitive and highly specific, the development of high quality protein antibody is both expensive and time consuming. The limited capability of assay multiplexing also makes the measurement an extremely low throughput one rendering it impractical when hundreds to thousands potential biomarkers need to be quantitatively measured across multiple samples. Mass spectrometry (MS)-based assays have recently shown to be a viable alternative for high throughput and quantitative candidate protein biomarker verification. Among them, the triple quadrupole MS based assay is the most promising one. When it is coupled with liquid chromatography (LC) separation and electrospray ionization (ESI) source, a triple quadrupole mass spectrometer operating in a special selected reaction monitoring (SRM) mode

  20. High Sensitivity MEMS Strain Sensor: Design and Simulation

    Directory of Open Access Journals (Sweden)

    Edmond Lou

    2008-04-01

    Full Text Available In this article, we report on the new design of a miniaturized strain microsensor. The proposed sensor utilizes the piezoresistive properties of doped single crystal silicon. Employing the Micro Electro Mechanical Systems (MEMS technology, high sensor sensitivities and resolutions have been achieved. The current sensor design employs different levels of signal amplifications. These amplifications include geometric, material and electronic levels. The sensor and the electronic circuits can be integrated on a single chip, and packaged as a small functional unit. The sensor converts input strain to resistance change, which can be transformed to bridge imbalance voltage. An analog output that demonstrates high sensitivity (0.03mV/me, high absolute resolution (1μe and low power consumption (100μA with a maximum range of ±4000μe has been reported. These performance characteristics have been achieved with high signal stability over a wide temperature range (±50oC, which introduces the proposed MEMS strain sensor as a strong candidate for wireless strain sensing applications under harsh environmental conditions. Moreover, this sensor has been designed, verified and can be easily modified to measure other values such as force, torque…etc. In this work, the sensor design is achieved using Finite Element Method (FEM with the application of the piezoresistivity theory. This design process and the microfabrication process flow to prototype the design have been presented.

  1. Compton imaging with a highly-segmented, position-sensitive HPGe detector

    Science.gov (United States)

    Steinbach, T.; Hirsch, R.; Reiter, P.; Birkenbach, B.; Bruyneel, B.; Eberth, J.; Gernhäuser, R.; Hess, H.; Lewandowski, L.; Maier, L.; Schlarb, M.; Weiler, B.; Winkel, M.

    2017-02-01

    A Compton camera based on a highly-segmented high-purity germanium (HPGe) detector and a double-sided silicon-strip detector (DSSD) was developed, tested, and put into operation; the origin of γ radiation was determined successfully. The Compton camera is operated in two different modes. Coincidences from Compton-scattered γ-ray events between DSSD and HPGe detector allow for best angular resolution; while the high-efficiency mode takes advantage of the position sensitivity of the highly-segmented HPGe detector. In this mode the setup is sensitive to the whole 4π solid angle. The interaction-point positions in the 36-fold segmented large-volume HPGe detector are determined by pulse-shape analysis (PSA) of all HPGe detector signals. Imaging algorithms were developed for each mode and successfully implemented. The angular resolution sensitively depends on parameters such as geometry, selected multiplicity and interaction-point distances. Best results were obtained taking into account the crosstalk properties, the time alignment of the signals and the distance metric for the PSA for both operation modes. An angular resolution between 13.8° and 19.1°, depending on the minimal interaction-point distance for the high-efficiency mode at an energy of 1275 keV, was achieved. In the coincidence mode, an increased angular resolution of 4.6° was determined for the same γ-ray energy.

  2. Selective and Sensitive Chemiluminescence Determination of MCPB: Flow Injection and Liquid Chromatography.

    Science.gov (United States)

    Meseguer-Lloret, Susana; Torres-Cartas, Sagrario; Catalá-Icardo, Mónica; Gómez-Benito, Carmen

    2016-02-01

    Two new chemiluminescence (CL) methods are described for the determination of the herbicide 4-(4-chloro-o-tolyloxy) butyric acid (MCPB). First, a flow injection chemiluminescence (FI-CL) method is proposed. In this method, MCPB is photodegraded with an ultraviolet (UV) lamp and the photoproducts formed provide a great CL signal when they react with ferricyanide in basic medium. Second, a high-performance liquid chromatography chemiluminescence (HPLC-CL) method is proposed. In this method, before the photodegradation and CL reaction, the MCPB and other phenoxyacid herbicides are separated in a C18 column. The experimental conditions for the FI-CL and HPLC-CL methods are optimized. Both methods present good sensitivity, the detection limits being 0.12 µg L(-1) and 0.1 µg L(-1) (for FI-CL and HPLC-CL, respectively) when solid phase extraction (SPE) is applied. Intra- and interday relative standard deviations are below 9.9%. The methods have been satisfactorily applied to the analysis of natural water samples. FI-CL method can be employed for the determination of MCPB in simple water samples and for the screening of complex water samples in a fast, economic, and simple way. The HPLC-CL method is more selective, and allows samples that have not been resolved with the FI-CL method to be solved.

  3. In vivo emergence of HIV-1 highly sensitive to neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    Marlén M I Aasa-Chapman

    Full Text Available BACKGROUND: The rapid and continual viral escape from neutralizing antibodies is well documented in HIV-1 infection. Here we report in vivo emergence of viruses with heightened sensitivity to neutralizing antibodies, sometimes paralleling the development of neutralization escape. METHODOLOGY/PRINCIPAL FINDINGS: Sequential viral envs were amplified from seven HIV-1 infected men monitored from seroconversion up to 5 years after infection. Env-recombinant infectious molecular clones were generated and tested for coreceptor use, macrophage tropism and neutralization sensitivity to homologous and heterologous serum, soluble CD4 and monoclonal antibodies IgG1b12, 2G12 and 17b. We found that HIV-1 evolves sensitivity to contemporaneous neutralizing antibodies during infection. Neutralization sensitive viruses grow out even when potent autologous neutralizing antibodies are present in patient serum. Increased sensitivity to neutralization was associated with susceptibility of the CD4 binding site or epitopes induced after CD4 binding, and mediated by complex envelope determinants including V3 and V4 residues. The development of neutralization sensitive viruses occurred without clinical progression, coreceptor switch or change in tropism for primary macrophages. CONCLUSIONS: We propose that an interplay of selective forces for greater virus replication efficiency without the need to resist neutralizing antibodies in a compartment protected from immune surveillance may explain the temporal course described here for the in vivo emergence of HIV-1 isolates with high sensitivity to neutralizing antibodies.

  4. High-throughput, Highly Sensitive Analyses of Bacterial Morphogenesis Using Ultra Performance Liquid Chromatography.

    Science.gov (United States)

    Desmarais, Samantha M; Tropini, Carolina; Miguel, Amanda; Cava, Felipe; Monds, Russell D; de Pedro, Miguel A; Huang, Kerwyn Casey

    2015-12-25

    The bacterial cell wall is a network of glycan strands cross-linked by short peptides (peptidoglycan); it is responsible for the mechanical integrity of the cell and shape determination. Liquid chromatography can be used to measure the abundance of the muropeptide subunits composing the cell wall. Characteristics such as the degree of cross-linking and average glycan strand length are known to vary across species. However, a systematic comparison among strains of a given species has yet to be undertaken, making it difficult to assess the origins of variability in peptidoglycan composition. We present a protocol for muropeptide analysis using ultra performance liquid chromatography (UPLC) and demonstrate that UPLC achieves resolution comparable with that of HPLC while requiring orders of magnitude less injection volume and a fraction of the elution time. We also developed a software platform to automate the identification and quantification of chromatographic peaks, which we demonstrate has improved accuracy relative to other software. This combined experimental and computational methodology revealed that peptidoglycan composition was approximately maintained across strains from three Gram-negative species despite taxonomical and morphological differences. Peptidoglycan composition and density were maintained after we systematically altered cell size in Escherichia coli using the antibiotic A22, indicating that cell shape is largely decoupled from the biochemistry of peptidoglycan synthesis. High-throughput, sensitive UPLC combined with our automated software for chromatographic analysis will accelerate the discovery of peptidoglycan composition and the molecular mechanisms of cell wall structure determination.

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

    Science.gov (United States)

    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.

  6. Effect of high gamma-doses in the sensitization of natural quartz for thermoluminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Khoury, H.J.; Guzzo, P.L.; Brito, S.B. [Universidade Federal de Pernambuco, 50740-540 Recife PE (Brazil)

    2006-07-01

    Sensitization is an important effect in radiation dosimetry using thermoluminescent (TL materials where the enhancement of sensitivity is a desirable feature. Until known, the investigation of sensitization in quartz has been restricted to its first glow peak appearing around 110 C. In addition, the sensitization process has been essentially produced by heat-treatments in powdered quartz. The aim of this study is to investigate the sensitization process in the second glow peak of crystalline quartz using high doses of gamma irradiation. For this, five lots of samples were prepared from quartz single crystals issued from different geologies in Brazil. Chips of 5 x 5 x 1 mm{sup 3} (60 mg) were cut and lapped parallel to the (0001) plane. The specimens were initially irradiated with doses of gamma radiation of {sup 137} Cs in the range of 10 mGy to 10 Gy in order to determine its TL response curve. After that, the specimens were submitted to successive high doses of gamma-irradiation with {sup 60} Co from 25 kGy to 350 kGy. After each irradiation, the TL response curves to gamma radiation of {sup 137} Cs were determined for each quartz lot irradiated in the range of 2 to 20 mGy. The TL measurements were carried out with a 2800M Victoreen reader using the step mode. The step parameters were set in 10 s from 30 to 160 C (first region) and in 20 s from 160 to 320 C (second region). The absolute TL signal used to obtain the calibration curves represented the sum of electric charges under the glow peak appearing in the second region. The results showed that the TL response of the quartz studied increased with the dose sensitization, so that the TL response for 10mGy of {sup 137} Cs radiation varied from 0.05 nC/mg for the quartz without sensitization to 10 nC/mg after a sensitization with 50 kGy of gamma radiation of {sup 60} Co. The effect of sensitization with high doses of gamma irradiation was clearly observed for three quartz lots and it was observed that the high

  7. PlanetPol: A Very High Sensitivity Polarimeter

    Science.gov (United States)

    Hough, J. H.; Lucas, P. W.; Bailey, J. A.; Tamura, M.; Hirst, E.; Harrison, D.; Bartholomew-Biggs, M.

    2006-09-01

    We have built and used on several occasions an optical broadband stellar polarimeter, PlanetPol, which employs photoelastic modulators and avalanche photodiodes and achieves a photon-noise-limited sensitivity of at least 1 in 106 in fractional polarization. Observations of a number of polarized standards taken from the literature show that the accuracy of polarization measurements is ~1%. We have developed a method for accurately measuring the polarization of altitude-azimuth mounted telescopes by observing bright nearby stars at different parallactic angles, and we find that the on-axis polarization of the William Herschel Telescope is typically ~15 × 10-6, measured with an accuracy of a few parts in 107. The nearby stars (distance less than 32 pc) are found to have very low polarizations, typically a few ×10-6, indicating that very little interstellar polarization is produced close to the Sun and that their intrinsic polarization is also low. Although the polarimeter can be used for a wide range of astronomy, the very high sensitivity was set by the goal of detecting the polarization signature of unresolved extrasolar planets.

  8. Kinetics of Highly Sensitive Troponin T after Cardiac Surgery

    Directory of Open Access Journals (Sweden)

    Amr S. Omar

    2015-01-01

    Full Text Available Perioperative myocardial infarction (PMI confers a considerable risk in cardiac surgery settings; finding the ideal biomarker seems to be an ideal goal. Our aim was to assess the diagnostic accuracy of highly sensitive troponin T (hsTnT in cardiac surgery settings and to define a diagnostic level for PMI diagnosis. This was a single-center prospective observational study analyzing data from all patients who underwent cardiac surgeries. The primary outcome was the diagnosis of PMI through a specific level. The secondary outcome measures were the lengths of mechanical ventilation (LOV, stay in the intensive care unit (LOSICU, and hospitalization. Based on the third universal definition of PMI, patients were divided into two groups: no PMI (Group I and PMI (Group II. Data from 413 patients were analyzed. Nine patients fulfilled the diagnostic criteria of PMI, while 41 patients were identified with a 5-fold increase in their CK-MB (≥120 U/L. Using ROC analysis, a hsTnT level of 3,466 ng/L or above showed 90% sensitivity and 90% specificity for the diagnosis of PMI. Secondary outcome measures in patients with PMI were significantly prolonged. In conclusion, the hsTnT levels detected here paralleled those of CK-MB and a cut-off level of 3466 ng/L could be diagnostic of PMI.

  9. Development of a New, High Sensitivity 2000 kg Mechanical Balance.

    Science.gov (United States)

    Wang, Jian

    2017-04-13

    Mass measurement of more than 500 kg on an electronic mass comparator has no better repeatability and linearity of measurement for meeting the calibration requirement of over class F1 weights from pharmacy and power generation plants. For this purpose, a new 2000 kg mechanical balance was developed by the National Institute of Metrology (NIM). The advantages of measurement of more than 500 kg on a new 2000 kg mechanical balance are introduced in the paper. In order to obtain high measurement uncertainty, four vertical forces of two sides of beam are measured and used as reference for adjustment of the beam position. Laser displacement sensors in the indication system are more effective for decreasing reading errors caused by human vision. To improve the repeatability and sensitivity of the equipment, a synchronous lifting control is designed for synchronously lifting the beam ends along the vertical direction. A counterweight selection system is developed to get any combination of weights in a limited space. The sensitivity of the new mechanical balance for 2000 kg is more than 1.7 parts in 10(-4) rad/g. The extended uncertainties for the mechanical balance of 500 kg, 1000 kg and 2000 kg are 0.47 g, 1.8 g and 3.5 g respectively.

  10. New application of superconductors: High sensitivity cryogenic light detectors

    Science.gov (United States)

    Cardani, L.; Bellini, F.; Casali, N.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2017-02-01

    In this paper we describe the current status of the CALDER project, which is developing ultra-sensitive light detectors based on superconductors for cryogenic applications. When we apply an AC current to a superconductor, the Cooper pairs oscillate and acquire kinetic inductance, that can be measured by inserting the superconductor in a LC circuit with high merit factor. Interactions in the superconductor can break the Cooper pairs, causing sizable variations in the kinetic inductance and, thus, in the response of the LC circuit. The continuous monitoring of the amplitude and frequency modulation allows to reconstruct the incident energy with excellent sensitivity. This concept is at the basis of Kinetic Inductance Detectors (KIDs) that are characterized by natural aptitude to multiplexed read-out (several sensors can be tuned to different resonant frequencies and coupled to the same line), resolution of few eV, stable behavior over a wide temperature range, and ease in fabrication. We present the results obtained by the CALDER collaboration with 2×2 cm2 substrates sampled by 1 or 4 Aluminum KIDs. We show that the performances of the first prototypes are already competitive with those of other commonly used light detectors, and we discuss the strategies for a further improvement.

  11. Luminescent Lanthanide Reporters for High-Sensitivity Novel Bioassays.

    Energy Technology Data Exchange (ETDEWEB)

    Anstey, Mitchell R.; Fruetel, Julia A.; Foster, Michael E.; Hayden, Carl C.; Buckley, Heather L.; Arnold, John

    2013-09-01

    Biological imaging and assay technologies rely on fluorescent organic dyes as reporters for a number of interesting targets and processes. However, limitations of organic dyes such as small Stokes shifts, spectral overlap of emission signals with native biological fluorescence background, and photobleaching have all inhibited the development of highly sensitive assays. To overcome the limitations of organic dyes for bioassays, we propose to develop lanthanide-based luminescent dyes and demonstrate them for molecular reporting applications. This relatively new family of dyes was selected for their attractive spectral and chemical properties. Luminescence is imparted by the lanthanide atom and allows for relatively simple chemical structures that can be tailored to the application. The photophysical properties offer unique features such as narrow and non-overlapping emission bands, long luminescent lifetimes, and long wavelength emission, which enable significant sensitivity improvements over organic dyes through spectral and temporal gating of the luminescent signal.Growth in this field has been hindered due to the necessary advanced synthetic chemistry techniques and access to experts in biological assay development. Our strategy for the development of a new lanthanide-based fluorescent reporter system is based on chelation of the lanthanide metal center using absorbing chromophores. Our first strategy involves "Click" chemistry to develop 3-fold symmetric chelators and the other involves use of a new class of tetrapyrrole ligands called corroles. This two-pronged approach is geared towards the optimization of chromophores to enhance light output.

  12. Quantum dots and p-phenylenediamine based method for the sensitive determination of glucose.

    Science.gov (United States)

    Lv, Xiaoxiao; Wang, Xiaoyu; Huang, Dawei; Niu, Chenggang; Zeng, Guangming; Niu, Qiuya

    2014-11-01

    By introducing p-phenylenediamine (PPD) to the hybrid system of Mn-doped CdS/ZnS quantum dots (QDs) and glucose oxidase (GOD), a sensitive label-free method was proposed for direct detection of glucose. With glucose and PPD as substrates, 2,5-diamino-N,N'-di-(4-aminophenyl)-2,5-cyclohexadiene-1,4-diimine (DDACD) that intensively quenches the fluorescence of QDs can be produced by the catalysis of GOD. A detection limit as low as 3.2 μM was obtained with the high-efficient fluorescence quencher. Two linear ranges, from 5.0 μM to 1000 μM and from 1.0 mM to 10.0 mM, were identified between time-gated fluorescence intensity and the concentration of glucose. It is shown that the newly proposed methods have high selectivity for glucose over other saccharides and coexisting biological species in serum. The method can be used directly to determine glucose in normal adult human serum without any complicated sample pretreatments. The recovery rate and repeatability of the method were also shown to be satisfactory.

  13. Bioluminometric assay of ATP in mouse brain: Determinant factors for enhanced test sensitivity

    Indian Academy of Sciences (India)

    Haseeb Ahmad Khan

    2003-06-01

    Firefly luciferase bioluminescence (FLB) is a highly sensitive and specific method for the analysis of adenosine-5-triphosphate (ATP) in biological samples. Earlier attempts to modify the FLB test for enhanced sensitivity have been typically based on in vitro cell systems. This study reports an optimized FLB procedure for the analysis of ATP in small tissue samples. The results showed that the sensitivity of the FLB test can be enhanced several fold by using ultraturax homogenizer, perchloric acid extraction, neutralization of acid extract and its optimal dilution, before performing the assay reaction.

  14. Magnetic probe array with high sensitivity for fluctuating field.

    Science.gov (United States)

    Kanamaru, Yuki; Gota, Hiroshi; Fujimoto, Kayoko; Ikeyama, Taeko; Asai, Tomohiko; Takahashi, Tsutomu; Nogi, Yasuyuki

    2007-03-01

    A magnetic probe array is constructed to measure precisely the spatial structure of a small fluctuating field included in a strong confinement field that varies with time. To exclude the effect of the confinement field, the magnetic probes consisting of figure-eight-wound coils are prepared. The spatial structure of the fluctuating field is obtained from a Fourier analysis of the probe signal. It is found that the probe array is more sensitive to the fluctuating field with a high mode number than that with a low mode number. An experimental demonstration of the present method is attempted using a field-reversed configuration plasma, where the fluctuating field with 0.1% of the confinement field is successfully detected.

  15. High Efficiency of Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    Liyuan Han

    2005-01-01

    @@ 1Introduction Much attention has been paid to the development of dye-sensitized solar cells (DSCs) during the past decade. In general, a DSC comprises a nanocrystalline titanium dioxide (TiO2) electrode modified with a dye fabricated on a transparent conducting oxide (TCO), a platinum (Pt) counter electrode, and an electrolyte solution with a dissolved iodide ion/tri-iodide ion redox couple between the electrodes. Although a DSC using black dye with high efficiency of 10.4%, which was measured by NREL(U. S. A. ), was reported by Graetzel et al. [1], the efficiency of DSCs should be further improved for practical use in comparison with silicon solar cells.

  16. High efficiency solid-state sensitized heterojunction photovoltaic device

    KAUST Repository

    Wang, Mingkui

    2010-06-01

    The high molar extinction coefficient heteroleptic ruthenium dye, NaRu(4,4′-bis(5-(hexylthio)thiophen-2-yl)-2,2′-bipyridine) (4-carboxylic acid-4′-carboxylate-2,2′-bipyridine) (NCS) 2, exhibits certified 5% electric power conversion efficiency at AM 1.5 solar irradiation (100 mW cm-2) in a solid-state dye-sensitized solar cell using 2,2′,7,7′-tetrakis-(N,N-di-pmethoxyphenylamine)-9, 9′-spirobifluorene (spiro-MeOTAD) as the organic hole-transporting material. This demonstration elucidates a class of photovoltaic devices with potential for low-cost power generation. © 2010 Elsevier Ltd. All rights reserved.

  17. A Highly Sensitive Refractometric Sensor Based on Cascaded SiN Microring Resonators

    Directory of Open Access Journals (Sweden)

    Daniel Pergande

    2013-10-01

    Full Text Available We investigate a highly sensitive optical sensor based on two cascaded microring resonators exploiting the Vernier effect. The architecture consists of two microrings with a slight difference in their free spectral ranges. This allows the generation of the Vernier effect for achieving ultra-high sensitivities. The sensor chip was fabricated using a silicon nitride platform and characterized with isopropanol/ethanol mixtures. A sensitivity of 0.95 nm/% was found for isopropanol concentrations in ethanol ranging from 0% to 10%. Furthermore, a collection of measurements was carried out using aqueous sodium chloride (NaCl in solutions of different concentrations, confirming a high sensitivity of 10.3 nm/% and a bulk refractive index sensitivity of 6,317 nm/RIU. A limit of detection of 3.16 ´ 10−6 RIU was determined. These preliminary results show the potential features of cascaded silicon nitride microring resonators for real-time and free-label monitoring of biomolecules for a broad range of applications.

  18. A highly sensitive refractometric sensor based on cascaded SiN microring resonators.

    Science.gov (United States)

    Zamora, Vanessa; Lützow, Peter; Weiland, Martin; Pergande, Daniel

    2013-10-28

    We investigate a highly sensitive optical sensor based on two cascaded microring resonators exploiting the Vernier effect. The architecture consists of two microrings with a slight difference in their free spectral ranges. This allows the generation of the Vernier effect for achieving ultra-high sensitivities. The sensor chip was fabricated using a silicon nitride platform and characterized with isopropanol/ethanol mixtures. A sensitivity of 0.95 nm/% was found for isopropanol concentrations in ethanol ranging from 0% to 10%. Furthermore, a collection of measurements was carried out using aqueous sodium chloride (NaCl) in solutions of different concentrations, confirming a high sensitivity of 10.3 nm/% and a bulk refractive index sensitivity of 6,317 nm/RIU. A limit of detection of 3.16 × 10(-6) RIU was determined. These preliminary results show the potential features of cascaded silicon nitride microring resonators for real-time and free-label monitoring of biomolecules for a broad range of applications.

  19. An UPLC-MS/MS method for highly sensitive high-throughput analysis of phytohormones in plant tissues

    Directory of Open Access Journals (Sweden)

    Balcke Gerd Ulrich

    2012-11-01

    Full Text Available Abstract Background Phytohormones are the key metabolites participating in the regulation of multiple functions of plant organism. Among them, jasmonates, as well as abscisic and salicylic acids are responsible for triggering and modulating plant reactions targeted against pathogens and herbivores, as well as resistance to abiotic stress (drought, UV-irradiation and mechanical wounding. These factors induce dramatic changes in phytohormone biosynthesis and transport leading to rapid local and systemic stress responses. Understanding of underlying mechanisms is of principle interest for scientists working in various areas of plant biology. However, highly sensitive, precise and high-throughput methods for quantification of these phytohormones in small samples of plant tissues are still missing. Results Here we present an LC-MS/MS method for fast and highly sensitive determination of jasmonates, abscisic and salicylic acids. A single-step sample preparation procedure based on mixed-mode solid phase extraction was efficiently combined with essential improvements in mobile phase composition yielding higher efficiency of chromatographic separation and MS-sensitivity. This strategy resulted in dramatic increase in overall sensitivity, allowing successful determination of phytohormones in small (less than 50 mg of fresh weight tissue samples. The method was completely validated in terms of analyte recovery, sensitivity, linearity and precision. Additionally, it was cross-validated with a well-established GC-MS-based procedure and its applicability to a variety of plant species and organs was verified. Conclusion The method can be applied for the analyses of target phytohormones in small tissue samples obtained from any plant species and/or plant part relying on any commercially available (even less sensitive tandem mass spectrometry instrumentation.

  20. Association between high-sensitive troponin I and coronary artery calcification in a Danish general population

    DEFF Research Database (Denmark)

    Olson, Fredrik; Engborg, Jonathan; Grønhøj, Mette H.;

    2016-01-01

    BACKGROUND: High-sensitive troponin I (hs-TnI) is an individual predictor of future cardiovascular disease (CVD). However, the relationship between hs-TnI and coronary artery calcification (CAC) as determined by computed tomography (CT) has not previously been investigated in a general population....... METHODS: 1173 randomized, middle-aged subjects without known CVD underwent a non-contrast cardiac-CT scan for CAC determination. Hs-TnI was detected using ARCHITECT STAT High Sensitive Troponin-I immunoassay. Total 10-year cardiovascular mortality risk was estimated using HeartScore. The relationship...... between hs-TnI and CAC was assessed using logistic regression analyses and receiver operating characteristic curves (ROC). RESULTS: Concentrations of hs-TnI above the limit of detection were measured in 89.3% of all subjects. Presence of CAC (Agatston score >0) was detected in 29% in the lowest hs...

  1. High sensitivity moiré interferometry with compact achromatic interferometry

    Science.gov (United States)

    Czarnek, Robert

    Experimental observations and measurements are the sources of information essential for correct development of mathematical models of real structural materials. Moiré interferometry offers high sensitivity in full-field measurements of in-plane displacements on the surface of a specimen. Although it is a powerful method in experimental stress analysis, it has some shortcomings. One is that existing systems require highly coherent light. The only sufficient source of light for this application is a long cavity laser, which is relatively expensive and at best cumbersome. Another shortcoming is that measurements must be performed in a vibration-free environment, such as that found on a holographic table. These requirements limit the use of existing moiré interferometers to a holographic laboratory. In this paper a modified concept of compensation is presented, which permits the use of a chromatic source of light in a compact moiré system. The compensator provides order in the angles of incident light for each separate wavelength, so that the virtual reference grating created by each wavelength in a continuous spectrum is identical in frequency and spatial position. The result is a virtual reference grating that behaves exactly like that created in coherent light. With this development the use of a laser diode, which is a non-coherent light source of tiny dimensions, becomes practical. The special configuration of the optics that create the virtual grating allows its synchronization with the specimen grating and leads to an interferometer design that is relatively insensitive to the vibrations found in a mechanical testing laboratory. Sensitivity to relative motion is analyzed theoretically. This development provides the oppurtunity to apply moiré interferometry to solid mechanics problems that cannot be studied in an optics laboratory. Experimental verification of the optical concepts is provided. A compact moiré interferometer based on the presented idea was

  2. Determination of Water Sensitivity Index in EstakoWest and Esan Central, Nigeria

    Directory of Open Access Journals (Sweden)

    Philipa O. Idogho

    2014-07-01

    Full Text Available As world population and industrial-agricultural outputs have increased, the use of water has accelerated. This development leads to extreme difficulty to provide sufficient safe drinking water in Etasko-West and Esan Central. Water sensitivity was measured in six major towns in Etasko-West and Esan Central. Water Measuring Indicators such as Water Poverty Index-Real Time (WPIr, Water Factor Value (WFV and Access-Demand Factor (γ were applied to generate water sensitivity iterations. The outputs of these iterations show that Irrua has the fairest water supply and distribution with WPIr, WFA and γ index value of 0.22; 0.77 and 0.76, while Auchi and Ewu experience acute water shortage with the following index values: WPIr-0.43, 0.39; WFV-0.06, 0.16; and γ-0.64, 0.6 respectively. Results of One-Sample Test and Paired Sample Statistics show that the proportion of monthly income spent on portable water is significant at 0.95 confidence interval in all towns, except Auchi. Comparative analysis indicates strong relationship (R 2=0.667 between the resources spent in procuring clean water and accessibility-demand ratio in the region. Private sector participation recorded highest investment value of 62% on water sector; government and corporate organization recorded 23% and 15% respectively. Since private sector determines the progresses of water sector, this accounts for the exorbitant tariff of 1, 500 N per m 3 in this region. It is deduced that the most significant problems faced with water accessibility-affordability are transportation, finance and power supply with computed constraint index value of 47%, 40% and 13% respectively. Finally, Etasko-West and Esan Central are highly waterstressed. Government, corporate organization and private investors need to establish technically-based measures to ensure perfect accessibility and affordability of this scarce utility.

  3. Simple Sensitive Spectrophotometric Determination of Vanadium in Biological and Environmental Samples

    Directory of Open Access Journals (Sweden)

    B. Krishna Priya

    2006-01-01

    Full Text Available Novel, rapid, highly sensitive and selective spectrophotometric method for the determination of traces of vanadium (V in environmental and biological samples, pharmaceutical and steel samples was studied. The method is based on oxidation of 2,4- dinitro phenyl hydrazine(2,4-DNPH by vanadium (V followed by coupling reaction with N-(1-naphthalene-1-ylethane-1,2-diamine-dihydrochloride (NEDA in acidic medium to give red colored derivative or on oxidation of 4-Amino Pyridine by vanadium (V followed by coupling reaction with NEDA in basic medium to give pink colored derivative. The red colored derivative having an λmax 495 nm which is stable for 8 days and the pink colored derivative with 525 nm is stable for more than 7 days at 350C. Beer's law is obeyed for vanadium (V in the concentration range of 0.02 - 3.5 μg mL–1 (red derivative and 0.03 – 4.5 μg mL–1 (pink derivative at the wave length of maximum absorption. The optimum reaction conditions and other analytical parameters were investigated to enhance the sensitivity of the present method. The detailed study of various interferences made the method more selective. The proposed method was successfully applied to the analysis of vanadium in natural water samples, plant material, soil samples, synthetic mixtures, pharmaceutical samples and biological samples. The results obtained were agreed with the reported methods at the 95 % confidence level. The performance of proposed method was evaluated in terms of Student's t-test and Variance ratio f-test which indicates the significance of proposed method over reported method.

  4. Sensitivity and specificity of serology in determining recent acute Campylobacter infection.

    Science.gov (United States)

    Taylor, B V; Williamson, J; Luck, J; Coleman, D; Jones, D; McGregor, A

    2004-05-01

    The measurement of serum antibodies to Campylobacter spp. has been used to investigate links between prior Campylobacter infections and the development of Guillain-Barre syndrome and its variants. Little is known of the serum antibody response to acute infections in the short- or long-term. The aims of the present study were to investigate the normal serum response to an acute Campylobacter infection and the sensitivity and specificity of anti-Campylobacter antibodies in determining recent Campylobacter infection. An enzyme-linked immunosorbent assay (ELISA) method was used to measure serum anti-Campylobacter immunoglobulin G (IgG), IgA and IgM antibodies. Controls consisted of 420 blood donors without recent gastroenteritis, 25 patients with other gastrointestinal infections, 24 patients with neurological conditions not affecting the peripheral nerves and 19 patients with autoimmune disorders. Three patient groups were assessed: 99 patients with acute Campylobacter infections, all of whom were tested 3 weeks post-infection; 69 of these patients tested 3-6 months later; and 74 additional patients tested >20 months post-infection. Western blot analysis was performed on controls and patients with high titre anti-Campylobacter antibodies to assess for cross-reactivity and specificity. Following acute infections, all antibody classes rose in the majority of but not in all patients, followed by decreasing titres that did not return to baseline levels. Sixteen per cent of enteritis cases did not demonstrate a rise in titres and 9% of cases had significant levels of antibodies >20 months post-infection. The ELISA used was shown to be highly specific for the detection of Campylobacter antibodies. The use of Campylobacter-specific antibody levels as the sole marker of prior infection is an unreliable method of determining the association between Campylobacter infection and neurological disease.

  5. Determination of Mass Sensitivity of Crystal Quartz Resonators at Students' Laboratory

    Science.gov (United States)

    Greczylo, Tomasz; Mazur, Piotr; Debowska, Ewa; Wieczorek, Piotr

    2010-01-01

    This paper presents an experiment in which students determine the mass sensitivity of three crystal quartz resonators, designed to be carried out in "Physics Laboratory II" at the Institute of Experimental Physics, University of Wroclaw. The authors discuss the process of setting up the experiment and the results of the measurements. They clearly…

  6. Determination of Mass Sensitivity of Crystal Quartz Resonators at Students' Laboratory

    Science.gov (United States)

    Greczylo, Tomasz; Mazur, Piotr; Debowska, Ewa; Wieczorek, Piotr

    2010-01-01

    This paper presents an experiment in which students determine the mass sensitivity of three crystal quartz resonators, designed to be carried out in "Physics Laboratory II" at the Institute of Experimental Physics, University of Wroclaw. The authors discuss the process of setting up the experiment and the results of the measurements.…

  7. A rapid method for determining salinomycin and monensin sensitivity in Eimeria tenella

    Science.gov (United States)

    Standard methods of determining the ionophore sensitivity of Eimeria rely on infecting chickens with an isolate or a mixture of Eimeria spp. oocysts in the presence of different anti-coccidial drugs. The purpose of this study was to develop a rapid in vitro method for assessing salinomycin and mone...

  8. Determining pancreatic β-cell compensation for changing insulin sensitivity using an oral glucose tolerance test

    DEFF Research Database (Denmark)

    Solomon, Thomas; Malin, Steven K; Karstoft, Kristian

    2014-01-01

    Plasma glucose, insulin, and C-peptide responses during an OGTT are informative for both research and clinical practice in type 2 diabetes. The aim of this study was to use such information to determine insulin sensitivity and insulin secretion so as to calculate an oral glucose disposition index...

  9. Scanning Auger microscopy for high lateral and depth elemental sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, E., E-mail: eugenie.martinez@cea.fr [CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Yadav, P. [CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Bouttemy, M. [Institut Lavoisier de Versailles, 45 av. des Etats-Unis, 78035 Versailles Cedex (France); Renault, O.; Borowik, Ł.; Bertin, F. [CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Etcheberry, A. [Institut Lavoisier de Versailles, 45 av. des Etats-Unis, 78035 Versailles Cedex (France); Chabli, A. [CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2013-12-15

    Highlights: •SAM performances and limitations are illustrated on real practical cases such as the analysis of nanowires and nanodots. •High spatial elemental resolution is shown with the analysis of reference semiconducting Al{sub 0.7}Ga{sub 0.3}As/GaAs multilayers. •High in-depth elemental resolution is also illustrated. Auger depth profiling with low energy ion beams allows revealing ultra-thin layers (∼1 nm). •Analysis of cross-sectional samples is another effective approach to obtain in-depth elemental information. -- Abstract: Scanning Auger microscopy is currently gaining interest for investigating nanostructures or thin multilayers stacks developed for nanotechnologies. New generation Auger nanoprobes combine high lateral (∼10 nm), energy (0.1%) and depth (∼2 nm) resolutions thus offering the possibility to analyze the elemental composition as well as the chemical state, at the nanometre scale. We report here on the performances and limitations on practical examples from nanotechnology research. The spatial elemental sensitivity is illustrated with the analysis of Al{sub 0.7}Ga{sub 0.3}As/GaAs heterostructures, Si nanowires and SiC nanodots. Regarding the elemental in-depth composition, two effective approaches are presented: low energy depth profiling to reveal ultra-thin layers (∼1 nm) and analysis of cross-sectional samples.

  10. Laser-engraved carbon nanotube paper for instilling high sensitivity, high stretchability, and high linearity in strain sensors

    KAUST Repository

    Xin, Yangyang

    2017-06-29

    There is an increasing demand for strain sensors with high sensitivity and high stretchability for new applications such as robotics or wearable electronics. However, for the available technologies, the sensitivity of the sensors varies widely. These sensors are also highly nonlinear, making reliable measurement challenging. Here we introduce a new family of sensors composed of a laser-engraved carbon nanotube paper embedded in an elastomer. A roll-to-roll pressing of these sensors activates a pre-defined fragmentation process, which results in a well-controlled, fragmented microstructure. Such sensors are reproducible and durable and can attain ultrahigh sensitivity and high stretchability (with a gauge factor of over 4.2 × 10(4) at 150% strain). Moreover, they can attain high linearity from 0% to 15% and from 22% to 150% strain. They are good candidates for stretchable electronic applications that require high sensitivity and linearity at large strains.

  11. Alemtuzumab induction therapy in highly sensitized kidney transplant recipients

    Institute of Scientific and Technical Information of China (English)

    L(U) Tie-ming; YANG Shun-liang; WU Wei-zhen; TAN Jian-ming

    2011-01-01

    Background Immunosuppression for immunologically high-risk kidney transplant patients usually involves antithymocyte globulin induction with triple drug maintenance therapy. Alemtuzumab, a humanized anti-CD52 antibody,was expected to be a promising induction therapy agent for kidney transplantation. However, currently no consensus is available about its efficacy and safety. This study aimed to evaluate the efficacy and safety of alemtuzumab as immune induction therapy in highly sensitized kidney transplant recipients.Methods In this prospective, open-label, randomized, controlled trial, we enrolled 23 highly immunological risk patients (panel reactive antibody >20%). They were divided into two groups: alemtuzumab group (trial group) and anti-thymocyte globulin (ATG) group (control group). Patients in the alemtuzumab group received intravenous alemtuzumab (15 mg) as a single dose before reperfusion. At the 24th hour post-operation, another dosage of alemtuzumab (15 mg) was given.The control group received a bolus of rabbit ATG (9 mg/kg), which was given 2 hours before kidney transplantation and lasted until the removal of vascular clamps when the anastomoses were completed. Maintenance immunosuppression in both groups comprised standard triple therapy consisting of tacrolimus, prednisone, and mycophenolate mofetil (MMF).Acute rejection (AR) and infection episodes were recorded, and kidney function was monitored during a 2-year follow-up.χ2 test, t test and Kaplan-Meier analysis were performed with SPSS17.0 software.Results Median follow-up was 338 days. In both the alemtuzumab group and ATG group, creatinine and blood urea nitrogen values in surviving recipients were similar (P >0.05). White blood cell counts were significantly reduced in the alemtuzumab group for the most time points up to 6 months (P <0.05). One patient receiving alemtuzumab died for acute myocardial infarction at the 65th day post-operation. Two ATG patients died for severe pulmonary

  12. Detection and Analysis of High Temperature Sensitivity of TGMS Lines in Rice Using AMMI Model

    Institute of Scientific and Technical Information of China (English)

    FU Li-zhong; XUE Qing-zhong

    2004-01-01

    With the AMMI(additive main effects and multiplicative interaction)analysis model,the determination of the sensitivity to temperature among different TGMS(thermo-sensitive genic male sterile)lines was performed. To assess the genetic differences due to high temperature stress at. the fertility-sensitive stage(10- 20 d before heading),seven genotypes(six TGMS lines and the control Pei-Ai64S)were grown from May 4 at seven different stages with 10d intervals. The temperatures at. the fertility-sensitive stages involved twelve levels from < 20 to >30℃ under the regime natural conditions in Hangzhou,China. There was considerable variation in pollen fertility among genotypes in response to high temperature. Five genotypes identified as TGMS lines as their percentages of fertile pollens were lower than or close to that. of the. control except for the unstable line RTS19(V6). When the temperatures at. the fertility-sensitive stage were at Ⅰ -Ⅳ,Ⅴ-Ⅵ and Ⅶ-Ⅻ,the percentages of fertile pollens varied in the ranges of 46.46- 48.49%,19.62-22.79% and 3.49- 5.87%,respectively. The critical temperatures of sterility and fertility in the five TGMS lines were 25.1 and 23.0℃,respectively. Considering the amounts and directions of main effect and their IPCA(interaction principal components analysis),we can classify the lines and temperature levels into different groups,and describe the characteristics of genotyPe x temperature interaction,offering the information and tools for the development and utility of thermo-sensitive male sterile lines.Several TGMS rice lines with their reproductive sensitivity to high temperature that can be screened using the AMMI model may add valuable germplasm to the breeding program of hybrid rice.

  13. Sensitive Adsorptive Voltammetric Method for Determination of Bisphenol A by Gold Nanoparticle/Polyvinylpyrrolidone-Modified Pencil Graphite Electrode.

    Science.gov (United States)

    Yaman, Yesim Tugce; Abaci, Serdar

    2016-05-25

    A novel electrochemical sensor gold nanoparticle (AuNP)/polyvinylpyrrolidone (PVP) modified pencil graphite electrode (PGE) was developed for the ultrasensitive determination of Bisphenol A (BPA). The gold nanoparticles were electrodeposited by constant potential electrolysis and PVP was attached by passive adsorption onto the electrode surface. The electrode surfaces were characterized by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The parameters that affected the experimental conditions were researched and optimized. The AuNP/PVP/PGE sensor provided high sensitivity and selectivity for BPA recognition by using square wave adsorptive stripping voltammetry (SWAdSV). Under optimized conditions, the detection limit was found to be 1.0 nM. This new sensor system offered the advantages of simple fabrication which aided the expeditious replication, low cost, fast response, high sensitivity and low background current for BPA. This new sensor system was successfully tested for the detection of the amount of BPA in bottled drinking water with high reliability.

  14. Innovative nanostructures for highly sensitive vibrational biosensing (Conference Presentation)

    Science.gov (United States)

    Popp, Juergen; Mayerhöfer, Thomas; Cialla-May, Dana; Weber, Karina; Huebner, Uwe

    2016-03-01

    Employing vibrational spectroscopy (IR-absorption and Raman spectroscopy) allows for the labelfree detection of molecular specific fingerprints of inorganic, organic and biological substances. The sensitivity of vibrational spectroscopy can be improved by several orders of magnitude via the application of plasmonic active surfaces. Within this contribution we will discuss two such approaches, namely surface enhanced Raman spectroscopy (SERS) as well as surface enhanced IR absorption (SEIRA). It will be shown that SERS using metal colloids as SERS active substrate in combination with a microfluidic lab-on-a-chip (LOC) device enables high throughput and reproducible measurements with highest sensitivity and specificity. The application of such a LOC-SERS approach for therapeutic drug monitoring (e.g. quantitative detection of antibiotics in a urine matrix) will be presented. Furthermore, we will introduce innovative bottom-up strategies to prepare SERS-active nanostructures coated with a lipophilic sensor layer as one-time use SERS substrates for specific food analysis (e.g. quantitative detection of toxic food colorants). The second part of this contribution presents a slit array metamaterial perfect absorber for IR sensing applications consisting of a dielectric layer sandwiched between two metallic layers of which the upper layer is perforated with a periodic array of slits. Light-matter interaction is greatly amplified in the slits, where also the analyte is concentrated, as the surface of the substrate is covered by a thin silica layer. Thus, already small concentrations of analytes down to a monolayer can be detected by refractive index sensing and identified by their spectral fingerprints with a standard mid-infrared lab spectrometer.

  15. Conducting polymer nanofibers for high sensitivity detection of chemical analytes.

    Science.gov (United States)

    Kumar, Abhishek; Leshchiner, Ignaty; Nagarajan, Subhalakshmi; Nagarajan, Ramaswamy; Kumar, Jayant

    2008-03-01

    Possessing large surface area materials is vital for high sensitivity detection of analyte. We report a novel, inexpensive and simple technique to make high surface area sensing interfaces using electrospinning. Conducting polymers (CP) nanotubes were made by electrospinning a solution of a catalyst (ferric tosylate) along with poly (lactic acid), which is an environment friendly biodegradable polymer. Further vapor deposition polymerization of the monomer ethylenedioxy thiophene (EDOT) on the nanofiber surface yielded poly (EDOT) covered fibers. X-ray photo electron spectroscopy (XPS) study reveals the presence of PEDOT predominantly on the surface of nanofibers. Conducting nanotubes had been received by dissolving the polymer in the fiber core. By a similar technique we had covalently incorporated fluorescent dyes on the nanofiber surface. The materials obtained show promise as efficient sensing elements. UV-Vis characterization confirms the formation of PEDOT nanotubes and incorporation of chromophores on the fiber surface. The morphological characterization was carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  16. Accelerated Sensitivity Analysis in High-Dimensional Stochastic Reaction Networks.

    Science.gov (United States)

    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

  17. Incorporation of beams into bossed diaphragm for a high sensitivity and overload micro pressure sensor

    Science.gov (United States)

    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.

  18. A more sensitive radioimmunoassay for neuron-specific enolase suitable for cerebrospinal fluid determinations.

    Science.gov (United States)

    Parma, A M; Marangos, P J; Goodwin, F K

    1981-03-01

    Neuron-specific enolase (NSE) and non-neuronal enolase (NNE) have been shown to be highly specific neuronal and glial products respectively and are therefore useful as biochemical markers of the two major cell types in the vertebrate central nervous system. An iodinated radioimmunoassay (RIA) procedure for human NSE (NSE-H) with approximately 50-fold greater sensitivity than the previously available tritiated assay is described. This assay is capable of detecting 100 pg of NSE-H per assay. NSE levels in human cerebrospinal fluid (CSF) which were previously undetectable with the tritiated RIA are now easily measured and have been shown to be approximately 2 ng/ml of CSF. Furthermore, results obtained with the newly described assay procedure on more concentrated brain tissue extracts are comparable to the tritiated RIA. The iodinated NSE RIA is also shown to be capable of accurately detecting added amounts of NSE in human CSF, indicating the potential clinical usefulness of this assay in determining elevated levels of NSE in CSF.

  19. Sensitive determination of ranitidine in rabbit plasma by HPLC with fluorescence detection.

    Science.gov (United States)

    Khedr, Alaa

    2008-02-01

    A sensitive high-performance liquid chromatographic method for determination of ranitidine (RAN) in rabbit plasma is described. The method is based on liquid-liquid extraction, labeling with dansyl chloride and monitoring with fluorescence detector at 338nm (ex)/523nm (em). Plasma samples were extracted with diethyl ether alkalinized with 1M sodium hydroxide. Ephedrine HCl (EPH-HCl) was used as internal standard. Both, RAN and EPH were completely derivatized after heating at 60 degrees C for 10min in sodium bicarbonate solution (pH 9.5). The derivatized samples were analyzed by HPLC using Agilent Zorbax Extended C18 column (150mmx4.6mm i.d.) and mobile phase consists of 48% acetonitrile and 52% sodium acetate solution (0.02M, pH 4.6). The linearity of the method was in the range of 0.025-10microg/ml. The limits of detection (LOD) and quantification (LOQ) were 7.5+/-0.18 and 22.5+/-0.12ng/ml, respectively. Ranitidine recovery was 97.5+/-1.1% (n=6; R.S.D.=1.8%). The method was applied on plasma collected from rabbits at different time intervals after oral administration of 5mg/kg ranitidine HCl.

  20. Determining the sensitivity of Data Envelopment Analysis method used in airport benchmarking

    Directory of Open Access Journals (Sweden)

    Mircea BOSCOIANU

    2013-03-01

    Full Text Available In the last decade there were some important changes in the airport industry, caused by the liberalization of the air transportation market. Until recently airports were considered infrastructure elements, and they were evaluated only by traffic values or their maximum capacity. Gradual orientation towards commercial led to the need of finding another ways of evaluation, more efficiency oriented. The existing methods for assessing efficiency used for other production units were not suitable to be used in case of airports due to specific features and high complexity of airport operations. In the last years there were some papers that proposed the Data Envelopment Analysis as a method for assessing the operational efficiency in order to conduct the benchmarking. This method offers the possibility of dealing with a large number of variables of different types, which represents the main advantage of this method and also recommends it as a good benchmarking tool for the airports management. This paper goal is to determine the sensitivity of this method in relation with its inputs and outputs. A Data Envelopment Analysis is conducted for 128 airports worldwide, in both input- and output-oriented measures, and the results are analysed against some inputs and outputs variations. Possible weaknesses of using DEA for assessing airports performance are revealed and analysed against this method advantages.

  1. Position-Sensitive Detector with Depth-of-Interaction Determination for Small Animal PET

    CERN Document Server

    Fedorov, A; Kholmetsky, A L; Korzhik, M V; Lecoq, P; Lobko, A S; Missevitch, O V; Tkatchev, A

    2002-01-01

    Crystal arrays made of LSO and LuAP crystals 2x2x10 mm pixels were manufactured for evaluation of detector with depth-of-interaction (DOI) determination capability intended for small animal positron emission tomograph. Position-sensitive LSO/LuAP phoswich DOI detector based on crystal 8x8 arrays and HAMAMATSU R5900-00-M64 position-sensitive multi-anode photomultiplier tube was developed and evaluated. Time resolution was found to be not worse than 1.0 ns FWHM for both layers, and spatial resolution mean value was 1.5 mm FWHM for the center of field-of-view.

  2. Sensitive immunochemical approaches for quantitative (FPIA) and qualitative (lateral flow tests) determination of gentamicin in milk.

    Science.gov (United States)

    Beloglazova, N V; Shmelin, P S; Eremin, S A

    2016-01-01

    Three kinds of immunoassays for the determination of gentamicin in milk samples were developed and validated. First, a fast and easily-performed fluorescence polarization immunoassay was used for characterization of the employed polyclonal antibody. The calculated Kaff were (1.9±0.4)×10(9)М(-1) and (6.0±0.2)×10(6)М(-1) for the high- and low-affinity fractions respectively. The assay was characterized with a good sensitivity, the limit of detection being 5μgkg(-1). Two different kinds of detection labels, i.e. colloidal gold (CG) and quantum dots (QDs), were evaluated for use in lateral-flow format with respect to rapid visual on-site testing. The cut-off levels for both qualitative formats were selected based on the maximum level for gentamicin in milk established by the European Commission, 100μgkg(-1), resulting in a 10μgkg(-1) cut-off considering sample dilution. The intra-laboratory validation was performed with sterilized milk samples artificially spiked with gentamicin at concentrations less than, equal to, and greater than the cut-off level. It was shown that milk products could be analyzed without any sample preparation, except for dilution with the buffer solution. The rates of false-positive and false-negative results were below 5% for both labels. The different developed immunoassays were tested towards gentamicin determination in artificially-spiked and naturally contaminated milk samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Highly sensitive and multiplexed platforms for allergy diagnostics

    Science.gov (United States)

    Monroe, Margo R.

    Allergy is a disorder of the immune system caused by an immune response to otherwise harmless environmental allergens. Currently 20% of the US population is allergic and 90% of pediatric patients and 60% of adult patients with asthma have allergies. These percentages have increased by 18.5% in the past decade, with predicted similar trends for the future. Here we design sensitive, multiplexed platforms to detect allergen-specific IgE using the Interferometric Reflectance Imaging Sensor (IRIS) for various clinical settings. A microarray platform for allergy diagnosis allows for testing of specific IgE sensitivity to a multitude of allergens, while requiring only small volumes of patient blood sample. However, conventional fluorescent microarray technology is limited by i) the variation of probe immobilization, which hinders the ability to make quantitative, assertive, and statistically relevant conclusions necessary in immunodiagnostics and ii) the use of fluorophore labels, which is not suitable for some clinical applications due to the tendency of fluorophores to stick to blood particulates and require daily calibration methods. This calibrated fluorescence enhancement (CaFE) method integrates the low magnification modality of IRIS with enhanced fluorescence sensing in order to directly correlate immobilized probe (major allergens) density to allergen-specific IgE in patient serum. However, this platform only operates in processed serum samples, which is not ideal for point of care testing. Thus, a high magnification modality of IRIS was adapted as an alternative allergy diagnostic platform to automatically discriminate and size single nanoparticles bound to specific IgE in unprocessed, characterized human blood and serum samples. These features make IRIS an ideal candidate for clinical and diagnostic applications, such a POC testing. The high magnification (nanoparticle counting) modality in conjunction with low magnification of IRIS in a combined instrument

  4. Fluorescence derivatization of clarithromycin for high performance liquid chromatographic determination with fluorescence detection

    OpenAIRE

    Boonleang, J.

    2007-01-01

    Clarithromycin (CAM) is a semisynthetic macrolide antibiotic whose chemical structure has no suitable chromophore for highly sensitive and accurate direct determination. The aim of this study was toderivatize CAM with fluorescence-labeling compounds capable of enhancing the sensitivity of CAM determination. Two fluorescence-labeling compounds were used in this study, 9-fluorenylmethyloxycarbonylchloride (FMOC-Cl) and 1-naphthylisocyanate (NIC), both of which gave the fluorescent derivatives o...

  5. Simultaneous determination of 4-nitroanisole, 4-nitrophenol, and 4-nitrocatechol by phase-sensitive ac polarography.

    Science.gov (United States)

    Burgschat, H; Netter, K J

    1977-01-01

    Phase-sensitive ac polarography was applied to the simultaneous quantitative determination of 4-nitroanisole, 4-nitrophenol, and 4-nitrocatechol in alkaline solutions. Certain experimental precautions are necessary to determine each compound in the presence of the other two. Thus, 4-nitrocatechol is determined indirectly by forming a yellow ratio chelate with cupric ions, wheras 4-nitroansole is determined directly by the reduction waves of the nitro group. For the determination of 4-nitrophenol, the interferency by the simultaneously present 4-nitrocatechol must be eliminated by masking it by the addition of magnesium ions. The method described permits a qualitative and quantitative analysis of all three compounds in one solution since linear calibration curves are obtained.

  6. Determination of saffron quality by high-performance liquid chromatography.

    Science.gov (United States)

    Valle García-Rodríguez, M; Serrano-Díaz, Jéssica; Tarantilis, Petros A; López-Córcoles, Horacio; Carmona, Manuel; Alonso, Gonzalo L

    2014-08-13

    The aim of this work was to propose a high-performance liquid chromatography with diode array detection (HPLC-DAD) method for determining the three main compounds responsible for determining the quality of saffron (crocetin esters, picrocrocin, and safranal) by preparing an aqueous extract according to the ISO 3632 standard to solve the difficulty that this standard has for aroma and taste determination by ultraviolet-visible spectroscopy. Toward this aim, laboratory-isolated picrocrocin, a safranal standard with a purity of ≥ 88%, trans-crocetin di(β-D-gentiobiosyl) ester (trans-4-GG) and trans-crocetin (β-D-glucosyl)-(β-D-gentiobiosyl) ester (trans-3-Gg) standards, both with a purity of ≥ 99%, and 50 different saffron spice samples from Italy, Iran, Greece, and Spain were used in the intralaboratory validation of the HPLC method. The analytical method proposed was adequate in terms of linearity, selectivity, sensitivity, and accuracy for determining the three foremost parameters that define the quality of saffron using only a saffron solution prepared according to the ISO 3632 standard.

  7. Characterization of Three High Efficiency and Blue Sensitive Silicon Photomultipliers

    CERN Document Server

    Otte, Adam Nepomuk; Nguyen, Thanh; Purushotham, Dhruv

    2016-01-01

    We report about the optical and electrical characterization of three high efficiency and blue sensitive Silicon photomultipliers from FBK, Hamamatsu, and SensL. Key features of the tested devices when operated at 90% breakdown probability are peak photon detection efficiencies between 40% and 55%, temperature dependencies of gain and PDE that are less than 1%/$^{\\circ}$C, dark rates of $\\sim$50\\,kHz/mm$^{2}$ at room temperature, afterpulsing of about 2%, and direct optical crosstalk between 6% and 20%. The characteristics of all three devices impressively demonstrate how the Silicon-photomultiplier technology has improved over the past ten years. It is further demonstrated how the voltage and temperature characteristics of a number of quantities can be parameterized on the basis of physical models. The models provide a deeper understanding of the device characteristics over a wide bias and temperature range. They also serve as examples how producers could provide the characteristics of their SiPMs to users. A...

  8. Characterization of three high efficiency and blue sensitive silicon photomultipliers

    Science.gov (United States)

    Otte, Adam Nepomuk; Garcia, Distefano; Nguyen, Thanh; Purushotham, Dhruv

    2017-02-01

    We report about the optical and electrical characterization of three high efficiency and blue sensitive Silicon photomultipliers from FBK, Hamamatsu, and SensL. Key features of the tested devices when operated at 90% breakdown probability are peak photon detection efficiencies between 40% and 55%, temperature dependencies of gain and PDE that are less than 1%/°C, dark rates of ∼50 kHz/mm2 at room temperature, afterpulsing of about 2%, and direct optical crosstalk between 6% and 20%. The characteristics of all three devices impressively demonstrate how the Silicon-photomultiplier technology has improved over the past ten years. It is further demonstrated how the voltage and temperature characteristics of a number of quantities can be parameterized on the basis of physical models. The models provide a deeper understanding of the device characteristics over a wide bias and temperature range. They also serve as examples how producers could provide the characteristics of their SiPMs to users. A standardized parameterization of SiPMs would enable users to find the optimal SiPM for their application and the operating point of SiPMs without having to perform measurements thus significantly reducing design and development cycles.

  9. High Speed Pressure Sensitive Paint for Dynamic Testing

    Science.gov (United States)

    Pena, Carolina; Chism, Kyle; Hubner, Paul

    2016-11-01

    Pressure sensitive paint (PSP) allows engineers to obtain accurate, high-spatial-resolution measurements of pressure fields over a structure. The pressure is directly related to the luminescence emitted by the paint due to oxygen quenching. Fast PSP has a higher surface area due to its porosity compared to conventional PSP, which enables faster diffusion and measurements to be acquired three orders of magnitude faster than with conventional PSP. A fast time response is needed when testing vibrating structures due to fluid-structure interaction. The goal of this summer project was to set-up, test and analyze the pressure field of an impinging air jet on a vibrating cantilever beam using Fast PSP. Software routines were developed for the processing of the emission images, videos of a static beam coated with Fast PSP were acquired with the air jet on and off, and the intensities of these two cases were ratioed and calibrated to pressure. Going forward, unsteady pressures on a vibrating beam will be measured and presented. Eventually, the long-term goal is to integrate luminescent pressure and strain measurement techniques, simultaneously using Fast PSP and a luminescent photoelastic coating on vibrating structures. Funding from NSF REU site Grant EEC 1358991 is greatly appreciated.

  10. Ultra-high sensitivity imaging of cancer using SERRS nanoparticles

    Science.gov (United States)

    Kircher, Moritz F.

    2016-05-01

    "Surface-enhanced Raman spectroscopy" (SERS) nanoparticles have gained much attention in recent years for in silico, in vitro and in vivo sensing applications. Our group has developed novel generations of biocompatible "surfaceenhanced resonance Raman spectroscopy" (SERRS) nanoparticles as novel molecular imaging agents. Via rigorous optimization of the different variables contributing to the Raman enhancement, we were able to design SERRS nanoparticles with so far unprecedented sensitivity of detection under in vivo imaging conditions (femto-attomolar range). This has resulted in our ability to visualize, with a single nanoparticle, many different cancer types (after intravenous injection) in mouse models. The cancer types we have tested so far include brain, breast, esophagus, stomach, pancreas, colon, sarcoma, and prostate cancer. All mouse models used are state-of-the-art and closely mimic the tumor biology in their human counterparts. In these animals, we were able to visualize not only the bulk tumors, but importantly also microscopic extensions and locoregional satellite metastases, thus delineating for the first time the true extent of tumor spread. Moreover, the particles enable the detection of premalignant lesions. Given their inert composition they are expected to have a high chance for clinical translation, where we envision them to have an impact in various scenarios ranging from early detection, image-guidance in open or minimally invasive surgical procedures, to noninvasive imaging in conjunction with spatially offset (SESORS) Raman detection devices.

  11. Fabrication of highly efficient flexible dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Chang, H., E-mail: f10381@ntut.edu.t [Department of Mechanical Engineering, National Taipei University of Technology, No.1 Sec.3, Chung Hsiao E. Rd., Taipei 10608, Taiwan (China); Chen, T.L. [Department of Industrial Design, National Taipei University of Technology, No.1 Sec.3, Chung Hsiao E. Rd., Taipei 10608, Taiwan (China); Huang, K.D. [Department of Vehicle Engineering, National Taipei University of Technology, No.1 Sec.3, Chung Hsiao E. Rd., Taipei 10608, Taiwan (China); Chien, S.H. [Institute of Chemistry, Academia Sinica, No. 128 Sec.2, Academia Rd., Nankang, Taipei 11529, Taiwan (China); Hung, K.C. [Department of Mechanical Engineering, National Taipei University of Technology, No.1 Sec.3, Chung Hsiao E. Rd., Taipei 10608, Taiwan (China)

    2010-08-15

    The paper studies the fabrication of a flexible dye-sensitized solar cell (DSSC). The photoelectrode substrates are flexible stainless steel sheet with thickness 0.07 mm and titanium (Ti) sheet with thickness 0.25 mm. For the photoelectrode fabrication process, eletrophoresis deposition (EPD) was employed for its merits of low-cost and fast fabrication. With an electric field of 40 V/cm, after undergoing EPD process twice, the TiO{sub 2} nanofilm thickness could be controlled to around 13 {mu}m thick. In addition, to achieve counter electrode, sputtering method was applied to deposit Pt on ITO-PET, resulting in thin films with four different thicknesses of 5, 8, 11 and 14 nm. The experimental results showed that the best colloid solution used in EPD process was a mixture of 100 ml isopropyl alcohol (IPA) and 0.4 g commercial TiO{sub 2} nanoparticles, Degussa P25. The best flatness for a 13 {mu}m thick film could be acquired under an electric field of 40 V/cm. Comparing the photoelectric conversion efficiency values of DSSC assembled by counter electrodes with different Pt thicknesses, the experimental results showed that the best Pt thickness was 11 nm, and the conversion efficiency could reach as high as 2.91%.

  12. ASIC for High Rate 3D Position Sensitive Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, E.; De Geronimo, G.; Ackley, K.; Fried, J.; He, Z.; Herman, C.; Zhang, F.

    2010-06-16

    We report on the development of an application specific integrated circuit (ASIC) for 3D position sensitive detectors (3D PSD). The ASIC is designed to operate with pixelated wide bandgap sensors like Cadmium-Zinc-Telluride (CZT), Mercuric Iodide (Hgl2) and Thallium Bromide (TIBr). It measures the amplitudes and timings associated with an ionizing event on 128 anodes, the anode grid, and the cathode. Each channel provides low-noise charge amplification, high-order shaping with peaking time adjustable from 250 ns to 12 {micro}s, gain adjustable to 20 mV/fC or 120 mV/fC (for a dynamic range of 3.2 MeV and 530 keV in CZT), amplitude discrimination with 5-bit trimming, and positive and negative peak and timing detections. The readout can be full or sparse, based on a flag and single- or multi-cycle token passing. All channels, triggered channels only, or triggered with neighbors can be read out thus increasing the rate capability of the system to more than 10 kcps. The ASIC dissipates 330 mW which corresponds to about 2.5 mW per channel.

  13. Adjoint sensitivity analysis of high frequency structures with Matlab

    CERN Document Server

    Bakr, Mohamed; Demir, Veysel

    2017-01-01

    This book covers the theory of adjoint sensitivity analysis and uses the popular FDTD (finite-difference time-domain) method to show how wideband sensitivities can be efficiently estimated for different types of materials and structures. It includes a variety of MATLAB® examples to help readers absorb the content more easily.

  14. Highly sensitive NIR PtSi/Si-nanostructure detectors

    Science.gov (United States)

    Li, Hua-gao; Guo, Pei; Yuan, An-bo; Long, Fei; Li, Rui-zhi; Li, Ping; Li, Yi

    2016-10-01

    We report a high external quantum efficiency (EQE) photodiode detector with PtSi/Si-nanostructures. Black silicon nanostructures were fabricated by metal-assist chemical etching (MCE), a 2 nm Pt layer was subsequently deposited on black silicon surface by DC magnetron sputtering system, and PtSi/Si-nanostructures were formed in vacuum annealing at 450 oC for 5 min. As the PtSi/Si-nanostructures presented a spiky shape, the absorption of incident light was remarkably enhanced for the repeat reflection and absorption. The breakdown voltage, dark current, threshold voltage and responsivity of the device were investigated to evaluate the performance of the PtSi/Si-nanostructures detector. The threshold voltage and dark currents of the PtSi/Si-nanostructure photodiode tends to be slightly higher than those of the standard diodes. The breakdown voltage remarkably was reduced because of existing avalanche breakdown in PtSi/Si-nanostructures. However, the photodiodes had high response at room temperature in near infrared region. At -5 V reverse bias voltage, the responsivity was 0.72 A/W in 1064 nm wavelength, and the EQE was 83.9%. By increasing the reverse bias voltage, the responsivity increased. At -60 V reverse bias voltage, the responsivity was 3.5 A/W, and the EQE was 407.5%, which means the quantum efficiency of PtSi/Si-nanostructure photodiodes was about 10 times higher than that of a standard diode. Future research includes how to apply this technology to enhance the NIR sensitivity of image sensors, such as Charge Coupled Devices (CCD).

  15. An assay to determine the sensitive window of embryos to chemical exposure using Xenopus tropicalis.

    Science.gov (United States)

    Hu, Lingling; Wu, Lijiao; Xue, Yingang; Zhu, Jingmin; Shi, Huahong

    2016-05-01

    The frog embryo teratogenesis assay-Xenopus (FETAX) is an established method to evaluate the developmental toxicity of chemicals. In FETAX, a 48 h continuous exposure is usually conducted when the X. tropicalis embryo is used as the test model. In the present study, we exposed X. tropicalis embryos to nine known teratogens for four separate 12-h periods. The embryos showed great variations in response to nine tested compounds during different exposure periods. Based on the value of the score of malformations, the most sensitive 12 h exposure periods of embryos were significantly distinguished for all the compounds with the exception of NiCl2 . The embryos were the most sensitive to retinols (e.g. all-trans-retinoic acid and 9-cis-retinoic acid) during 0-12 h and to metal compounds (e.g. triphenlytin and CdCl2) during a 24 to 36 h exposure period. In the further 3 h exposure experiment, the most sensitive period could only be determined for one of three tested compounds. Based on the present results, we proposed an assay to determine a 12 h sensitive window of embryos to chemical exposure using Xenopus tropicalis.

  16. High sensitivity of Giardia duodenalis to tetrahydrolipstatin (orlistat in vitro.

    Directory of Open Access Journals (Sweden)

    Juliane Hahn

    Full Text Available Giardiasis, a gastrointestinal disease caused by Giardia duodenalis, is currently treated mainly with nitroimidazoles, primarily metronidazole (MTZ. Treatment failure rates of up to 20 percent reflect the compelling need for alternative treatment options. Here, we investigated whether orlistat, a drug approved to treat obesity, represents a potential therapeutic agent against giardiasis. We compared the growth inhibitory effects of orlistat and MTZ on a long-term in vitro culture adapted G. duodenalis strain, WB-C6, and on a new isolate, 14-03/F7, from a patient refractory to MTZ treatment using a resazurin assay. The giardiacidal concentration of the drugs and their combined in vitro efficacy was determined by median-effect analysis. Morphological changes after treatment were analysed by light and electron microscopy. Orlistat inhibited the in vitro growth of G. duodenalis at low micromolar concentrations, with isolate 14-03/F7 (IC50(24h = 2.8 µM being more sensitive than WB-C6 (IC50(24h = 6.2 µM. The effect was significantly more potent compared to MTZ (IC50(24h = 4.3 µM and 11.0 µM, respectively and led to specific undulated morphological alterations on the parasite surface. The giardiacidal concentration of orlistat was >14 µM for 14-03/F7 and >43 µM for WB-C6, respectively. Importantly, the combination of both drugs revealed no interaction on their inhibitory effects. We demonstrate that orlistat is a potent inhibitor of G. duodenalis growth in vitro and kills parasites at concentrations achievable in the gut by approved treatment regimens for obesity. We therefore propose to investigate orlistat in controlled clinical studies as a new drug in giardiasis.

  17. High sensitivity of Giardia duodenalis to tetrahydrolipstatin (orlistat) in vitro.

    Science.gov (United States)

    Hahn, Juliane; Seeber, Frank; Kolodziej, Herbert; Ignatius, Ralf; Laue, Michael; Aebischer, Toni; Klotz, Christian

    2013-01-01

    Giardiasis, a gastrointestinal disease caused by Giardia duodenalis, is currently treated mainly with nitroimidazoles, primarily metronidazole (MTZ). Treatment failure rates of up to 20 percent reflect the compelling need for alternative treatment options. Here, we investigated whether orlistat, a drug approved to treat obesity, represents a potential therapeutic agent against giardiasis. We compared the growth inhibitory effects of orlistat and MTZ on a long-term in vitro culture adapted G. duodenalis strain, WB-C6, and on a new isolate, 14-03/F7, from a patient refractory to MTZ treatment using a resazurin assay. The giardiacidal concentration of the drugs and their combined in vitro efficacy was determined by median-effect analysis. Morphological changes after treatment were analysed by light and electron microscopy. Orlistat inhibited the in vitro growth of G. duodenalis at low micromolar concentrations, with isolate 14-03/F7 (IC50(24h) = 2.8 µM) being more sensitive than WB-C6 (IC50(24h) = 6.2 µM). The effect was significantly more potent compared to MTZ (IC50(24h) = 4.3 µM and 11.0 µM, respectively) and led to specific undulated morphological alterations on the parasite surface. The giardiacidal concentration of orlistat was >14 µM for 14-03/F7 and >43 µM for WB-C6, respectively. Importantly, the combination of both drugs revealed no interaction on their inhibitory effects. We demonstrate that orlistat is a potent inhibitor of G. duodenalis growth in vitro and kills parasites at concentrations achievable in the gut by approved treatment regimens for obesity. We therefore propose to investigate orlistat in controlled clinical studies as a new drug in giardiasis.

  18. Determination of Mass Spectrometric Sensitivity of Different Metalloporphyrin Esters Relative to Porphyrin Ester

    DEFF Research Database (Denmark)

    Larsen, Elfinn; Egsgaard, Helge; Møller, J.

    1977-01-01

    Quantitative determination of metalloporphyrin contamination in preparations of biologically important porphyrins was achieved mass spectrometrically by application of the integrated ion current technique. For this purpose, the relative molecular ion sensitivities of the contaminating metal compl...... complexes were determined from the ratios of the integrated molecular ion currents of a series of calibration samples containing a porphyrin ester and one of its metal complexes in known molar ratio. Complexes formed with divalent ions of Cu, Zn, Fe, Co and Ni of copro- as well as uro......-prophyrin permethylester were all found to have the same molecular ion sensitivities as their metal-free porphyrin ester. The relative metalloporphyrin ester content in a sample of porphyrin ester was thus obtained directly as the integrated ion current ratios of the normalized molecular ions. The preparation...

  19. The Significance of Ultrasound in Determining Whether SHPT Patients Are Sensitive to Calcitriol Treatment.

    Science.gov (United States)

    Liang, Xing-xin; Li, Fan; Gao, Feng; Li, Chun-xiao; Qiao, Xiao-hui; Zhang, Jia-jie; Du, Lian-fang

    2016-01-01

    This study was to explore the significance of ultrasound in determining whether the patients with secondary hyperparathyroidism (SHPT) are sensitive to calcitriol treatment. According to the decrease value of parathyroid hormone (PTH), 42 SHPT patients were divided into two groups: drug susceptible group and drug insusceptible group. These 42 SHPT patients' ultrasound images were retrospectively analyzed. The morphology, size, number, blood flow, elastic modulus, and perfusion of the parathyroid glands were correlated with drug therapeutic outcome (oral calcitriol). Most SHPT patients with drug susceptible showed volume elastic modulus elastic modulus ≥18.8 kPa. Therefore, ultrasonography in SHPT allows an accurate definition of the morphology, size, number, blood flow, elastic modulus, and perfusion of the parathyroid glands and is useful in determining whether SHPT patients are sensitive to calcitriol treatment.

  20. A nanosilver-based spectrophotometry method for sensitive determination of tartrazine in food samples.

    Science.gov (United States)

    Sahraei, R; Farmany, A; Mortazavi, S S

    2013-06-01

    A new method is reported for sensitive determination of tartrazine in the food samples. The method is based on the catalytic effect of silver nanoparticle (AgNPs) on the oxidation reaction of tartrazine by potassium iodate in the acetate buffer medium. The reaction is followed spectrophotometrically by measuring the change in absorbance (ΔA) at 420 nm using a fixed time method (70 s). The reaction variables were optimised in order to achieve the highest sensitivity. The thirty six criterion detection limit was 0.3 ng/mL, and the relative standard deviation for ten replicate measurements of 30 ng/mL of tartrazine was 0.98% (n=10). The method was successfully applied to the determination of tartrazine in lemon, and papaya-flavoured gelatin, candy, and in fruit syrup.

  1. Methyl-β-Cyclodextrin /Cetyltrimethyl Ammonium Bromide Synergistic Sensitized Fluorescence Method for the Determination of Levofloxacin.

    Science.gov (United States)

    Ren, Qiuyi; Zhu, Xiashi

    2016-03-01

    A novel method of methyl-β-cyclodextrin (methyl-β-CD) and cetyltrimethyl ammonium bromide (CTAB) synergistic sensitized fluorescence analysis to determine levofloxacin (LVFX) was developed. The results were shown that the fluorescence intensity of LVFX was increased a lot in the system of methyl-β-cyclodextrin-CTAB medium. Under the conditions of λ(ex/em )= 330/507 nm and pH 4.5, the linear range and the detection limit for LVFX were found to be 0.040 ~ 4.0 μg/mL and 0.3 ng/mL, respectively. The mechanism of sensitized fluorescence method was discussed by the solubilization capacity and the microenvironment of medium. The proposed method has been applied for the determination of LVFX in eye drops real samples and human serum with satisfactory recovery.

  2. Single-acquisition method for simultaneous determination of extrinsic gamma-camera sensitivity and spatial resolution

    Energy Technology Data Exchange (ETDEWEB)

    Santos, J.A.M. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)], E-mail: a.miranda@portugalmail.pt; Sarmento, S. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Alves, P.; Torres, M.C. [Departamento de Fisica da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Bastos, A.L. [Servico de Medicina Nuclear, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Ponte, F. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)

    2008-01-15

    A new method for measuring simultaneously both the extrinsic sensitivity and spatial resolution of a gamma-camera in a single planar acquisition was implemented. A dual-purpose phantom (SR phantom; sensitivity/resolution) was developed, tested and the results compared with other conventional methods used for separate determination of these two important image quality parameters. The SR phantom yielded reproducible and accurate results, allowing an immediate visual inspection of the spatial resolution as well as the quantitative determination of the contrast for six different spatial frequencies. It also proved to be useful in the estimation of the modulation transfer function (MTF) of the image formation collimator/detector system at six different frequencies and can be used to estimate the spatial resolution as function of the direction relative to the digital matrix of the detector.

  3. The Significance of Ultrasound in Determining Whether SHPT Patients Are Sensitive to Calcitriol Treatment

    OpenAIRE

    Xing-xin Liang; Fan Li; Feng Gao; Chun-xiao Li; Xiao-hui Qiao; Jia-jie Zhang; Lian-fang Du

    2016-01-01

    This study was to explore the significance of ultrasound in determining whether the patients with secondary hyperparathyroidism (SHPT) are sensitive to calcitriol treatment. According to the decrease value of parathyroid hormone (PTH), 42 SHPT patients were divided into two groups: drug susceptible group and drug insusceptible group. These 42 SHPT patients' ultrasound images were retrospectively analyzed. The morphology, size, number, blood flow, elastic modulus, and perfusion of the parathyr...

  4. High-sensitivity high-throughput chip based biosensor array for multiplexed detection of heavy metals

    Science.gov (United States)

    Yan, Hai; Tang, Naimei; Jairo, Grace A.; Chakravarty, Swapnajit; Blake, Diane A.; Chen, Ray T.

    2016-03-01

    Heavy metal ions released into the environment from industrial processes lead to various health hazards. We propose an on-chip label-free detection approach that allows high-sensitivity and high-throughput detection of heavy metals. The sensing device consists of 2-dimensional photonic crystal microcavities that are combined by multimode interferometer to form a sensor array. We experimentally demonstrate the detection of cadmium-chelate conjugate with concentration as low as 5 parts-per-billion (ppb).

  5. High levels of dietary stearate promote adiposity and deteriorate hepatic insulin sensitivity

    Directory of Open Access Journals (Sweden)

    Havekes Louis M

    2010-03-01

    resistance. These results indicate that dietary fatty acid composition per sé rather than dietary fat content determines insulin sensitivity in liver of high fat fed C57Bl/6 mice.

  6. Determination of pyrazinamide in human by high performance liquid chromatography.

    Directory of Open Access Journals (Sweden)

    Revankar S

    1994-01-01

    Full Text Available A facile and sensitive high performance liquid chromatographic (HPLC technique has been developed for the determination pyrazinamide (PZA in human plasma. Nicotinamide(NIA is used as internal standard(IS. Plasma is deproteinized with 0.7 M perchloric acid; clear supernatant is neutralized with 1M NaOH and injected onto HPLC. The separation of pyrazinamide and the internal standard is carried out on a Supelco LC-18 (DB column with a basic mobile phase. Pyrazinoic acid, the major metabolite, other anti-tuberculous drugs and endogenous components do not interfere with measurement of pyrazinamide. The limit of detection of pyrazinamide with this method is 0.2 mg/0.2 ml plasma (CV 8.2%.

  7. Highly Sensitive Marker Panel for Guidance in Lung Cancer Rapid Diagnostic Units

    Science.gov (United States)

    Blanco-Prieto, Sonia; De Chiara, Loretta; Rodríguez-Girondo, Mar; Vázquez-Iglesias, Lorena; Rodríguez-Berrocal, Francisco Javier; Fernández-Villar, Alberto; Botana-Rial, María Isabel; de la Cadena, María Páez

    2017-01-01

    While evidence for lung cancer screening implementation in Europe is awaited, Rapid Diagnostic Units have been established in many hospitals to accelerate the early diagnosis of lung cancer. We seek to develop an algorithm to detect lung cancer in a symptomatic population attending such unit, based on a sensitive serum marker panel. Serum concentrations of Epidermal Growth Factor, sCD26, Calprotectin, Matrix Metalloproteinases −1, −7, −9, CEA and CYFRA 21.1 were determined in 140 patients with respiratory symptoms (lung cancer and controls with/without benign pathology). Logistic Lasso regression was performed to derive a lung cancer prediction model, and the resulting algorithm was tested in a validation set. A classification rule based on EGF, sCD26, Calprotectin and CEA was established, able to reasonably discriminate lung cancer with 97% sensitivity and 43% specificity in the training set, and 91.7% sensitivity and 45.4% specificity in the validation set. Overall, the panel identified with high sensitivity stage I non-small cell lung cancer (94.7%) and 100% small-cell lung cancers. Our study provides a sensitive 4-marker classification algorithm for lung cancer detection to aid in the management of suspicious lung cancer patients in the context of Rapid Diagnostic Units. PMID:28117344

  8. The optimal condition of performing MTT assay for the determination of radiation sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Semie; Kim, Il Han [College of Medicine, Seoul National Univ., Seoul (Korea, Republic of)

    2001-06-01

    The measurement of radiation survival using a clonogenic assay, the established standard, can be difficult and time consuming. In this study, We have used the MTT assay, based on the reduction of a tetrazolium salt to a purple formazan precipitate by living cells, as a substitution for clonogenic assay and have examined the optimal condition for performing this assay in determination of radiation sensitivity. Four human cancer cell lines - PCI-1, SNU-1066, NCI-H63O and RKO cells have been used. For each cell line, a clonogenic assay and a MTT assay using Premix WST-1 solution, which is one of the tetrazolium salts and does not require washing or solubilization of the precipitate were carried out after irradiation of 0, 2, 4, 6, 8, 10 Gy, For clonogenic assay, cells in 25 cm{sup 2} flasks were irradiated after overnight incubation and the resultant colonies containing more than 50 cells were scored after culturing the cells for 10-14 days, For MTT assay, the relationship between absorbance and cell number, optimal seeding cell number, and optimal timing of assay was determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth or when the non-irradiated cells had undergone four or more doubling times. There was minimal variation in the values gained from these two methods with the standard deviation generally less than 5%, and there were no statistically significant differences between two methods according to t-test in low radiation dose (below 6 Gy). The regression analyses showed high linear correlation with the R{sup 2} value of 0.975-0.992 between data from the two different methods. The optimal cell numbers for MTT assay were found to be dependent on plating efficiency of used cell line. Less than 300 cells/well were appropriate for cells with high plating efficiency (more than 30%). For cells with low plating efficiency (less than 30%), 500 cells/well or more were appropriate for assay. The optimal time for MTT assay was

  9. High sensitivity fiber Bragg grating pressure difference sensor

    Institute of Scientific and Technical Information of China (English)

    Haiwei Fu(傅海威); Junmei Fu(傅君眉); Xueguang Qiao(乔学光)

    2004-01-01

    Based on the effect of fiber Bragg grating (FBG) pressure difference sensitivity enhancement by encapsulating the FBG with uniform strength beam and metal bellows, a FBG pressure difference sensor is proposed, and its mechanism is also discussed. The relationship between Bragg wavelength and the pressure difference is derived, and the expression of the pressure difference sensitivity coefficient is also given. It is indicated that there is good linear relation between the Bragg wavelength shift and the pressure difference of the sensor. The theoretical and experimental pressure difference sensitivity coefficients are 38.67 and 37.6 nm/MPa, which are 12890 and 12533 times of that of the bare FBG, respectively. The pressure difference sensitivity and dynamic range can be easily changed by changing the size, Young's modulus, and Poisson's ratio of the beam and the bellows.

  10. Design of a High Sensitivity GNSS receiver for Lunar missions

    Science.gov (United States)

    Musumeci, Luciano; Dovis, Fabio; Silva, João S.; da Silva, Pedro F.; Lopes, Hugo D.

    2016-06-01

    This paper presents the design of a satellite navigation receiver architecture tailored for future Lunar exploration missions, demonstrating the feasibility of using Global Navigation Satellite Systems signals integrated with an orbital filter to achieve such a scope. It analyzes the performance of a navigation solution based on pseudorange and pseudorange rate measurements, generated through the processing of very weak signals of the Global Positioning System (GPS) L1/L5 and Galileo E1/E5 frequency bands. In critical scenarios (e.g. during manoeuvres) acceleration and attitude measurements from additional sensors complementing the GNSS measurements are integrated with the GNSS measurement to match the positioning requirement. A review of environment characteristics (dynamics, geometry and signal power) for the different phases of a reference Lunar mission is provided, focusing on the stringent requirements of the Descent, Approach and Hazard Detection and Avoidance phase. The design of High Sensitivity acquisition and tracking schemes is supported by an extensive simulation test campaign using a software receiver implementation and navigation results are validated by means of an end-to-end software simulator. Acquisition and tracking of GPS and Galileo signals of the L1/E1 and L5/E5a bands was successfully demonstrated for Carrier-to-Noise density ratios as low as 5-8 dB-Hz. The proposed navigation architecture provides acceptable performances during the considered critical phases, granting position and velocity errors below 61.4 m and 3.2 m/s, respectively, for the 99.7% of the mission time.

  11. Characterization of a high resolution and high sensitivity pre-clinical PET scanner with 3D event reconstruction

    CERN Document Server

    Rissi, M; Bolle, E; Dorholt, O; Hines, K E; Rohne, O; Skretting, A; Stapnes, S; Volgyes, D

    2012-01-01

    COMPET is a preclinical PET scanner aiming towards a high sensitivity, a high resolution and MRI compatibility by implementing a novel detector geometry. In this approach, long scintillating LYSO crystals are used to absorb the gamma-rays. To determine the point of interaction (P01) between gamma-ray and crystal, the light exiting the crystals on one of the long sides is collected with wavelength shifters (WLS) perpendicularly arranged to the crystals. This concept has two main advantages: (1) The parallax error is reduced to a minimum and is equal for the whole field of view (FOV). (2) The P01 and its energy deposit is known in all three dimension with a high resolution, allowing for the reconstruction of Compton scattered gamma-rays. Point (1) leads to a uniform point source resolution (PSR) distribution over the whole FOV, and also allows to place the detector close to the object being imaged. Both points (1) and (2) lead to an increased sensitivity and allow for both high resolution and sensitivity at the...

  12. A high sensitive fiber-optic strain sensor with tunable temperature sensitivity for temperature-compensation measurement

    Science.gov (United States)

    Hu, Jie; Huang, Hui; Bai, Min; Zhan, Tingting; Yang, Zhibo; Yu, Yan; Qu, Bo

    2017-02-01

    A high sensitive fiber-optic strain sensor, which consists of a cantilever, a tandem rod and a fiber collimator, was proposed. The tandem rod, which transfer the applied strain to the cantilever, was used for tuning the temperature sensitivity from ‑0.15 to 0.19 dB/°C via changing the length ratio of the rods. Moreover, due to the small beam divergence of the collimator, high strain sensitivity can be realized via incident-angle sensitive detection-mechanism. A strain detection-range of 1.1 × 103 με (with a sensing length of 21.5 mm), a detection limit of 5.7 × 10‑3 με, and a maximum operating frequency of 1.18 KHz were demonstrated. This sensor is promising for compensating the thermal-expansion of various target objects.

  13. Metabolic determinants of cancer cell sensitivity to glucose limitation and biguanides

    Science.gov (United States)

    Birsoy, Kıvanç; Possemato, Richard; Lorbeer, Franziska K.; Bayraktar, Erol C.; Thiru, Prathapan; Yucel, Burcu; Wang, Tim; Chen, Walter W.; Clish, Clary B.; Sabatini, David M.

    2014-04-01

    As the concentrations of highly consumed nutrients, particularly glucose, are generally lower in tumours than in normal tissues, cancer cells must adapt their metabolism to the tumour microenvironment. A better understanding of these adaptations might reveal cancer cell liabilities that can be exploited for therapeutic benefit. Here we developed a continuous-flow culture apparatus (Nutrostat) for maintaining proliferating cells in low-nutrient media for long periods of time, and used it to undertake competitive proliferation assays on a pooled collection of barcoded cancer cell lines cultured in low-glucose conditions. Sensitivity to low glucose varies amongst cell lines, and an RNA interference (RNAi) screen pinpointed mitochondrial oxidative phosphorylation (OXPHOS) as the major pathway required for optimal proliferation in low glucose. We found that cell lines most sensitive to low glucose are defective in the OXPHOS upregulation that is normally caused by glucose limitation as a result of either mitochondrial DNA (mtDNA) mutations in complex I genes or impaired glucose utilization. These defects predict sensitivity to biguanides, antidiabetic drugs that inhibit OXPHOS, when cancer cells are grown in low glucose or as tumour xenografts. Notably, the biguanide sensitivity of cancer cells with mtDNA mutations was reversed by ectopic expression of yeast NDI1, a ubiquinone oxidoreductase that allows bypass of complex I function. Thus, we conclude that mtDNA mutations and impaired glucose utilization are potential biomarkers for identifying tumours with increased sensitivity to OXPHOS inhibitors.

  14. Corrosion Behavior of the Stressed Sensitized Austenitic Stainless Steels of High Nitrogen Content in Seawater

    Directory of Open Access Journals (Sweden)

    A. Almubarak

    2013-01-01

    Full Text Available The purpose of this paper is to study the effect of high nitrogen content on corrosion behavior of austenitic stainless steels in seawater under severe conditions such as tensile stresses and existence of sensitization in the structure. A constant tensile stress has been applied to sensitized specimens types 304, 316L, 304LN, 304NH, and 316NH stainless steels. Microstructure investigation revealed various degrees of stress corrosion cracking. SCC was severe in type 304, moderate in types 316L and 304LN, and very slight in types 304NH and 316NH. The electrochemical polarization curves showed an obvious second current peak for the sensitized alloys which indicated the existence of second phase in the structure and the presence of intergranular stress corrosion cracking. EPR test provided a rapid and efficient nondestructive testing method for showing passivity, degree of sensitization and determining IGSCC for stainless steels in seawater. A significant conclusion was obtained that austenitic stainless steels of high nitrogen content corrode at a much slower rate increase pitting resistance and offer an excellent resistance to stress corrosion cracking in seawater.

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

    Science.gov (United States)

    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.

  16. Transfer of a two-tiered keratinocyte assay: IL-18 production by NCTC2544 to determine the skin sensitizing capacity and epidermal equivalent assay to determine sensitizer potency

    DEFF Research Database (Denmark)

    Teunis, Marc; Corsini, Emanuela; Smits, Mieke

    2013-01-01

    . The two tiered approach may offer an unique opportunity to provide an alternative method to the Local Lymph Node Assay (LLNA). These assays are both based on the use of human keratinocytes, which have been shown over the last two decades, to play a key role in all phases of skin sensitization.......At present, the identification of potentially sensitizing chemicals is carried out using animal models. However, it is very important from ethical, safety and economic point of view to have biological markers to discriminate allergy and irritation events, and to be able to classify sensitizers...... sensitizers from non-sensitizers. This study describes two of these assays, which when used in a tiered strategy, may be able to identify contact sensitizers and also to quantify sensitizer potency. Tier 1 is the human keratinocyte NCTC2544 IL-18 assay and tier 2 is the Epidermal Equivalent potency assay...

  17. Sensitive Method for Enantioseparation of Rivastigmine with Highly Sulfated Cyclodextrin as Chiral Selector by Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    WANG Zhao-Yan; XU Xing-Xiang; HU Zhi-De; KANG Jing-Wu

    2006-01-01

    A sensitive method for enantioseparation of a basic drug rivastigmine and determination of its optical impurity by capillary electrophoresis with highly sulfatedβ-cyclodextrin (HS-β-CD) as the chiral selector is described. In general, enantioseparation of basic chiral compounds is carried out in acidic condition (pH 2.5) to prevent analytes from adsorption on the capillary wall. However, in the case of rivastigmine, the detection sensitivity was too limited to determine the optical impurity of S-rivastigmine lower than 1% when buffer pH was 2.5. It was found that the detection sensitivity was improved 1.6 times just by raising the buffer pH value from 2.5 to 5.8. The poor column efficiency due to the adsorption of the analytes on the capillary wall was resolved by using dynamical coating of the capillary wall with the linear polyacrylamide solution. The experimental parameters such as the concentration of HS-β-CD, buffer pH and buffer ionic strength were optimized, respectively. The method was validated in terms of repeatability, linearity, limit of detection (LOD) and limit of quantitation (LOQ). Using the present method, the optical purity of nonracemic rivastigmine with the enantiomeric excess (ee) value of 99.14% was determined.

  18. A sensitive diffusion sampler for the determination of volatile organic compounds in ambient air

    Science.gov (United States)

    Uchiyama, Shigehisa; Asai, Masae; Hasegawa, Shuji

    We developed a diffusive sampling device (DSD-voc) for volatile organic compounds (VOCs) which is suitable for collection of low level VOCs and analysis with thermal desorption. This sampling device is composed of two parts, an exposure part made of a porous polytetrafluoroethylene (PTFE) filter, and an analysis part made of stainless-steel tubing. The DSD-voc collects VOCs through the mechanism of molecular diffusion. Collection is controlled by moving the adsorbent from the exposure part to the analysis part by changing the posture of the DSD-voc. Adsorbates in the DSD-voc were analyzed by GC/MS with a thermal desorption cold trap injector (TCT). The TCT has the advantage of being able to accept the entire quantity of VOCs. We connected a condenser between the DSD-voc and the trap tube to prevent moisture from freezing in the trap tube when the sampler was packed with strong adsorbent. We also examined the desorption efficiency for VOCs from several types of adsorbents (Carboxen TM 1000, Carbosieve TM G, Carbosieve S III, Carbotrap TM B, and activated carbon) over a wide range of temperatures. Carboxen 1000 was suitable for the determination of VOCs with a low boiling point range, from CFC12 to hexane, while Carbotrap B was suitable for VOCs from hexane to 1,4-dichlorobenzene. The limits of detection with Carboxen 1000 and Carbotrap B were 0.036-0.046 and 0.0035-0.014 ppb, respectively, for a sampling duration of 24 h. Coefficients of variation for concentrations of major VOCs ranged from 3.8 to 14%. It is possible to estimate atmospheric VOCs at sub-parts per billion (sub-ppb), with high sensitivity, by using both adsorbents in combination.

  19. Determination of Finasteride in Tablets by High Performance Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    K. Basavaiah

    2007-01-01

    Full Text Available A rapid, highly sensitive high performance liquid chromatographic method has been developed for the determination of finasteride(FNS in bulk drug and in tablets. FNS was eluted from a ODS C18 reversed phase column at laboratory temperature (30 ± 2°C with a mobile phase consisting of methanol and water (80+20 at a flow rate of 1 mL min-1 with UV detection at 225 nm. The retention time was ∼ 6.1 min and each analysis took not more than 10 min. Quantitation was achieved by measurement of peak area without using any internal standard. Calibration graph was linear from 2.0 to 30 μg mL-1 with limits of detection (LOD and quantification (LOQ being 0.2 and 0.6 μg mL-1, respectively. The method was validated according to the current ICH guidelines. Within-day co efficients of variation (CV ranged from 0.31 to 0.69% and between-day CV were in the range 1.2-3.2%. Recovery of FNS from the pharmaceutical dosage forms ranged from 97.89 – 102.9 with CV of 1.41-4.13%. The developed method was compared with the official method for FNS determination in its tablet forms.

  20. Sensitive spectrophotometric methods for determination of some organophosphorus pesticides in vegetable samples

    Directory of Open Access Journals (Sweden)

    MAGDA A. AKL

    2010-03-01

    Full Text Available Three rapid, simple, reproducible and sensitive spectrophotometric methods (A, B and C are described for the determination of two organophosphorus pesticides, (malathion and dimethoate in formulations and vegetable samples. The methods A and B involve the addition of an excess of Ce4+ into sulphuric acid medium and the determination of the unreacted oxidant by decreasing the red color of chromotrope 2R (C2R at a suitable lmax = 528 nm for method A, or a decrease in the orange pink color of rhodamine 6G (Rh6G at a suitable lmax = = 525 nm. The method C is based on the oxidation of malathion or dimethoate with the slight excess of N-bromosuccinimide (NBS and the determination of unreacted oxidant by reacting it with amaranth dye (AM in hydrochloric acid medium at a suitable lmax = 520 nm. A regression analysis of Beer-Lambert plots showed a good correlation in the concentration range of 0.1-4.2 μg mL−1. The apparent molar absorptivity, Sandell sensitivity, the detection and quantification limits were calculated. For more accurate analysis, Ringbom optimum concentration ranges are 0.25-4.0 μg mL−1. The developed methods were successfully applied to the determination of malathion, and dimethoate in their formulations and environmental vegetable samples.

  1. High Precision Orbit Determination of CHAMP Satellite

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qile; LIU Jingnan; GE Maorong

    2006-01-01

    The precision orbit determination of challenging minisatellite payload(CHAMP) satellite was done based on position and navigation data analyst(PANDA) software which is developed in Wuhan University, using the onboard GPS data of year 2002 from day 126 to 131. The orbit accuracy was assessed by analyzing the difference from GFZ post-processed science orbits (PSO), the GPS carrier and pseudo-range data residuals and the satellite laser ranging (SLR) residuals.

  2. High spectral response heteroleptic ruthenium (II) complexes as sensitizers for dye sensitized solar cells

    Indian Academy of Sciences (India)

    M Chandrasekharam; Ch Srinivasarao; T Suresh; M Anil Reddy; M Raghavender; G Rajkumar; M Srinivasu; P Yella Reddy

    2011-01-01

    Heteroleptic ruthenium(II) bipyridyl complex, cis-Ru(II)(4,4'-bis(4-tert-butylstyryl)-2,2'-bipyridyl) (4,4'-dicarboxy-2,2'-bipyridyl) (NCS2) (H112) was synthesized and characterized by 1H-NMR, MASS, Spectrofluorometer and UV-Vis spectroscopes. The photo-voltaic performance of the sensitizer was evaluated in Dye Sensitized Solar Cell (DSSC) under irradiation of AM 1.5 G solar light and the photovoltaic characteristics were compared with those of reference cells of HRS1 and N719 fabricated under comparable conditions. Compared to N719, H112 sensitizer showed enhanced molar extinction coefficient and relatively better monochromatic incident photon-to-current conversion efficiency (IPCE) across the spectral range of 400 to 800 nm with solar energy-to-electrical conversion efficiency () of 2.43% [open circuit photovoltage (VOC) = 0.631V, short-circuit photocurrent density (JSC) = 8.96 mA/cm2, fill factor (ff) = 0.430], while values of 2.51% (VOC = 0.651V, JSC = 9.41 mA/cm2, ff = 0.410) and 2.74% (VOC = 0.705 V, JSC = 8.62 mA/cm2, ff = 0.455) were obtained for HRS1 and N719 sensitized solar cells respectively. The introduction of 4,4'-bis(4-tert-butylstyryl) moieties on one of the bipyridine moieties of N719 complex shows higher light absorption abilities, IPCE and JSC.

  3. Determination of flumioxazin residue in food samples through a sensitive fluorescent sensor based on click chemistry.

    Science.gov (United States)

    Lu, Lijun; Yang, Linlin; Cai, Huijian; Zhang, Lan; Lin, Zhenyu; Guo, Longhua; Qiu, Bin; Chen, Guonan

    2014-11-01

    A sensitive and selective fluorescent sensor for flumioxazin was designed based on the formation of strong fluorescence compound (1,2,3-triazole compounds) via the reaction of the alkynyl group in flumioxazin with 3-azido-7-hydroxycoumarin, a weak-fluorescent compound, through the Cu(+)-catalysed azide-alkyne cycloaddition (CuAAC) reaction. The fluorescence increase factor (represented by F/F0) of the system exhibited a good linear relationship with the concentrations of flumioxazin in the range of 0.25-6.0 μg/L with a detection limit of 0.18 μg/L (S/N=3). Also, the proposed fluorescent sensor demonstrated good selectivity for flumioxazin assay even in the presence of high concentration of other pesticides. Based on such high sensitivity and selectivity, the proposed fluorescent sensor has been applied to test the flumioxazin residue in some vegetable and water samples with satisfied results.

  4. Development of High Temperature/High Sensitivity Novel Chemical Resistive Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chonglin; Nash, Patrick; Ma, Chunrui; Enriquez, Erik; Wang, Haibing; Xu, Xing; Bao, Shangyong; Collins, Gregory

    2013-08-13

    The research has been focused to design, fabricate, and develop high temperature/high sensitivity novel multifunctional chemical sensors for the selective detection of fossil energy gases used in power and fuel systems. By systematically studying the physical properties of the LnBaCo{sub 2}O{sub 5+d} (LBCO) [Ln=Pr or La] thin-films, a new concept chemical sensor based high temperature chemical resistant change has been developed for the application for the next generation highly efficient and near zero emission power generation technologies. We also discovered that the superfast chemical dynamic behavior and an ultrafast surface exchange kinetics in the highly epitaxial LBCO thin films. Furthermore, our research indicates that hydrogen can superfast diffuse in the ordered oxygen vacancy structures in the highly epitaxial LBCO thin films, which suggest that the LBCO thin film not only can be an excellent candidate for the fabrication of high temperature ultra sensitive chemical sensors and control systems for power and fuel monitoring systems, but also can be an excellent candidate for the low temperature solid oxide fuel cell anode and cathode materials.

  5. Using satellites to investigate the sensitivity of longwave downward radiation to water vapor at high elevations

    Science.gov (United States)

    Naud, Catherine M.; Miller, James R.; Landry, Chris

    2012-03-01

    Many studies suggest that high-elevation regions may be among the most sensitive to future climate change. However, in situ observations in these often remote locations are too sparse to determine the feedbacks responsible for enhanced warming rates. One of these feedbacks is associated with the sensitivity of longwave downward radiation (LDR) to changes in water vapor, with the sensitivity being particularly large in many high-elevation regions where the average water vapor is often low. We show that satellite retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) can be used to expand the current ground-based observational database and that the monthly averaged clear-sky satellite estimates of humidity and LDR are in good agreement with the well-instrumented Center for Snow and Avalanche Studies ground-based site in the southwestern Colorado Rocky Mountains. The relationship between MODIS-retrieved precipitable water vapor and surface specific humidity across the contiguous United States was found to be similar to that previously found for the Alps. More important, we show that satellites capture the nonlinear relationship between LDR and water vapor and confirm that LDR is especially sensitive to changes in water vapor at high elevations in several midlatitude mountain ranges. Because the global population depends on adequate fresh water, much of which has its source in high mountains, it is critically important to understand how climate will change there. We demonstrate that satellites can be used to investigate these feedbacks in high-elevation regions where the coverage of surface-based observations is insufficient to do so.

  6. Dynamics and sensitivity analysis of high-frequency conduction block

    Science.gov (United States)

    Ackermann, D. Michael; Bhadra, Niloy; Gerges, Meana; Thomas, Peter J.

    2011-10-01

    The local delivery of extracellular high-frequency stimulation (HFS) has been shown to be a fast acting and quickly reversible method of blocking neural conduction and is currently being pursued for several clinical indications. However, the mechanism for this type of nerve block remains unclear. In this study, we investigate two hypotheses: (1) depolarizing currents promote conduction block via inactivation of sodium channels and (2) the gating dynamics of the fast sodium channel are the primary determinate of minimal blocking frequency. Hypothesis 1 was investigated using a combined modeling and experimental study to investigate the effect of depolarizing and hyperpolarizing currents on high-frequency block. The results of the modeling study show that both depolarizing and hyperpolarizing currents play an important role in conduction block and that the conductance to each of three ionic currents increases relative to resting values during HFS. However, depolarizing currents were found to promote the blocking effect, and hyperpolarizing currents were found to diminish the blocking effect. Inward sodium currents were larger than the sum of the outward currents, resulting in a net depolarization of the nodal membrane. Our experimental results support these findings and closely match results from the equivalent modeling scenario: intra-peritoneal administration of the persistent sodium channel blocker ranolazine resulted in an increase in the amplitude of HFS required to produce conduction block in rats, confirming that depolarizing currents promote the conduction block phenomenon. Hypothesis 2 was investigated using a spectral analysis of the channel gating variables in a single-fiber axon model. The results of this study suggested a relationship between the dynamical properties of specific ion channel gating elements and the contributions of corresponding conductances to block onset. Specifically, we show that the dynamics of the fast sodium inactivation gate are

  7. A high-sensitivity push-pull magnetometer

    Science.gov (United States)

    Breschi, E.; Grujić, Z. D.; Knowles, P.; Weis, A.

    2014-01-01

    We describe our approach to atomic magnetometry based on the push-pull optical pumping technique. Cesium vapor is pumped and probed by a resonant laser beam whose circular polarization is modulated synchronously with the spin evolution dynamics induced by a static magnetic field. The magnetometer is operated in a phase-locked loop, and it has an intrinsic sensitivity below 20fT/√Hz , using a room temperature paraffin-coated cell. We use the magnetometer to monitor magnetic field fluctuations with a sensitivity of 300fT/√Hz .

  8. A high-sensitivity push-pull magnetometer

    CERN Document Server

    Breschi, E; Knowles, P; Weis, A

    2013-01-01

    We describe our approach to atomic magnetometry based on the push-pull optical pumping technique. Cesium vapor is pumped and probed by a resonant laser beam whose circular polarization is modulated synchronously with the spin evolution dynamics induced by a static magnetic field. The magnetometer is operated in a phase-locked loop, and it has an intrinsic sensitivity below 20fT/\\sqrt(Hz) using a room temperature paraffin-coated cell. We use the magnetometer to monitor magnetic field fluctuations with a sensitivity of 300fT/\\sqrt(Hz).

  9. High Sensitivity SPECT for Small Animals and Plants

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Gregory S. [UC Davis

    2015-02-28

    Imaging systems using single gamma-ray emitting radioisotopes typically implement collimators in order to form the images. However, a tradeoff in sensitivity is inherent in the use of collimators, and modern preclinical single-photon emission computed tomography (SPECT) systems detect a very small fraction of emitted gamma-rays (<0.3%). We have built a collimator-less system, which can reach sensitivity of 40% for 99mTc imaging, while still producing images of sufficient spatial resolution for certain applications in thin objects such as mice, small plants, and well plates used for in vitro experiments.

  10. Test of the notch technique for determining the radial sensitivity of the optical model potential

    CERN Document Server

    Yang, Lei; Jia, Hui-ming; Xu, Xin-Xing; Ma, Nan-Ru; Sun, Li-Jie; Yang, Feng; Zhang, Huan-Qiao; Li, Zu-Hua; Wang, Dong-Xi

    2015-01-01

    Detailed investigations on the notch technique are performed on the ideal data generated by the optical model potential parameters extracted from the 16O+208Pb system at the laboratory energy of 129.5 MeV, to study the sensitivities of this technique on the model parameters as well as the experimental data. It is found that, for the perturbation parameters, a sufficient large reduced fraction and an appropriate small perturbation width are necessary to determine the accurate radial sensitivity; while for the potential parameters, almost no dependence was observed. For the experimental measurements, the number of data points has little influence for the heavy target system, and the relative inner information of the nuclear potential can be derived when the measurement extended to a lower cross section.

  11. Boronic acid functionalized N-doped carbon quantum dots as fluorescent probe for selective and sensitive glucose determination

    Science.gov (United States)

    Jiang, Guohua; Jiang, Tengteng; Li, Xia; Wei, Zheng; Du, Xiangxiang; Wang, Xiaohong

    2014-04-01

    Nitrogen doped carbon quantum dots (NCQDs) of about 10 nm in diameter have been obtained by hydrothermal reaction from collagen. Because of the superiority of water dispersion, low toxicity and ease of functionlization, the NCQDs were designed as a glucose sensor after covalent grafting by 3-aminophenylboronic (APBA) (APBA-NCQDs). The as-prepared APBA-NCQDs were imparted with glucose sensitivity and selectivity from other saccharides via fluorescence (FL) quenching effect at physiological pH and at room temperature, which show high sensitivity and specificity for glucose determination with a wide range from 1 mM to 14 mM. FL quenching mechanism of APBA-NCQDs was also investigated by adding an external quencher. The APBA-NCQDs-based platform is an environmentally friendly way to substitute inorganic quantum dots containing heavy metals which offer a facile and low cost detection method.

  12. A sensitive LC-MS/MS method for simultaneous determination of amygdalin and paeoniflorin in human plasma and its application.

    Science.gov (United States)

    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.

  13. Giardia lamblia allergenic extract as diagnosis procedures for determining sensitization to this protozoa.

    Science.gov (United States)

    Crespo Guerrero, V; Alfonso Fernández, L A; Gómez Echevarría, A H

    1991-12-01

    We studied 200 patients assisting at the Allergy Department and the Gastroenterology Department in "Hermanos Ameijeiras" Clinical-Surgical Hospital. They were clinically and immunologically tested for giardiasis through duodenal fortis or gall bladder drainage and total IgE serum levels. All patients underwent intradermal and skin prick tests with Giardine allergenic extract. These skin tests showed high sensitivity and increased specificity. Thus, our procedure in diagnosis is accurate, accessible and economical.

  14. High-speed high-sensitivity infrared spectroscopy using mid-infrared swept lasers (Conference Presentation)

    Science.gov (United States)

    Childs, David T. D.; Groom, Kristian M.; Hogg, Richard A.; Revin, Dmitry G.; Cockburn, John W.; Rehman, Ihtesham U.; Matcher, Stephen J.

    2016-03-01

    Infrared spectroscopy is a highly attractive read-out technology for compositional analysis of biomedical specimens because of its unique combination of high molecular sensitivity without the need for exogenous labels. Traditional techniques such as FTIR and Raman have suffered from comparatively low speed and sensitivity however recent innovations are challenging this situation. Direct mid-IR spectroscopy is being speeded up by innovations such as MEMS-based FTIR instruments with very high mirror speeds and supercontinuum sources producing very high sample irradiation levels. Here we explore another possible method - external cavity quantum cascade lasers (EC-QCL's) with high cavity tuning speeds (mid-IR swept lasers). Swept lasers have been heavily developed in the near-infrared where they are used for non-destructive low-coherence imaging (OCT). We adapt these concepts in two ways. Firstly by combining mid-IR quantum cascade gain chips with external cavity designs adapted from OCT we achieve spectral acquisition rates approaching 1 kHz and demonstrate potential to reach 100 kHz. Secondly we show that mid-IR swept lasers share a fundamental sensitivity advantage with near-IR OCT swept lasers. This makes them potentially able to achieve the same spectral SNR as an FTIR instrument in a time x N shorter (N being the number of spectral points) under otherwise matched conditions. This effect is demonstrated using measurements of a PDMS sample. The combination of potentially very high spectral acquisition rates, fundamental SNR advantage and the use of low-cost detector systems could make mid-IR swept lasers a powerful technology for high-throughput biomedical spectroscopy.

  15. Cavity Enhanced Optical Vernier Spectroscopy, Broad Band, High Resolution, High Sensitivity

    CERN Document Server

    Gohle, Christoph; Schliesser, Albert; Udem, Thomas; Hänsch, Theodor W

    2007-01-01

    A femtosecond frequency comb provides a vast number of equidistantly spaced narrow band laser modes that can be simultaneously tuned and frequency calibrated with 15 digits accuracy. Our Vernier spectrometer utilizes all of theses modes in a massively parallel manner to rapidly record both absorption and dispersion spectra with a sensitivity that is provided by a high finesse broad band optical resonator and a resolution that is only limited by the frequency comb line width while keeping the required setup simple.

  16. Pajarito Monitor: a high-sensitivity monitoring system for highly enriched uranium

    Energy Technology Data Exchange (ETDEWEB)

    Fehlau, P.E.; Coop, K.; Garcia, C. Jr.; Martinez, J.

    1984-01-01

    The Pajarito Monitor for Special Nuclear Material is a high-sensitivity gamma-ray monitoring system for detecting small quantities of highly enriched uranium transported by pedestrians or motor vehicles. The monitor consists of two components: a walk-through personnel monitor and a vehicle monitor. The personnel monitor has a plastic-scintillator detector portal, a microwave occupancy monitor, and a microprocessor control unit that measures the radiation intensity during background and monitoring periods to detect transient diversion signals. The vehicle monitor examines stationary motor vehicles while the vehicle's occupants pass through the personnel portal to exchange their badges. The vehicle monitor has four groups of large plastic scintillators that scan the vehicle from above and below. Its microprocessor control unit measures separate radiation intensities in each detector group. Vehicle occupancy is sensed by a highway traffic detection system. Each monitor's controller is responsible for detecting diversion as well as serving as a calibration and trouble-shooting aid. Diversion signals are detected by a sequential probability ratio hypothesis test that minimizes the monitoring time in the vehicle monitor and adapts itself well to variations in individual passage speed in the personnel monitor. Designed to be highly sensitive to diverted enriched uranium, the monitoring system also exhibits exceptional sensitivity for plutonium. 6 references, 9 figures, 2 tables.

  17. A sensitive fluorimetric method for determination of trace amounts of nitrite based on luminescence energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lun, E-mail: wanglun@mail.ahnu.edu.c [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Chen Jingguo; Chen Hongqi; Zhou Cailing; Ling Bo; Fu Jie [Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China)

    2011-01-15

    An efficient luminescence energy transfer (LET) system based on terbium(III)-sodium hexametaphosphate (Tb/SHMP) chelates as donor and 4-((4-(2-aminoethylamino)naphthalen-1-yl)diazenyl)benzenesulfonic acid dihydrochloride (ANDBS) as acceptor was developed for sensitive determination of trace nitrite. Stable and strong fluorescence Tb/SHMP chelates were prepared in aqueous solution. Based on Griess Reaction, ANDBS was generated by the quantitative reaction of nitrite, sulfanilamide and N-(1-naphtyl)-ethylenediamine dihydrochloride (N1NED). The degree of the overlap was effective for LET between the emission spectrum of Tb/SHMP chelates and the absorption spectrum of ANDBS. Based on the luminescence intensity quenching of Tb/SHMP chelates in proportion to the trace amounts of nitrite, a new assay for the selective and sensitive determination of nitrite was developed. Under the optimum conditions, the linear calibration graph was obtained with a linear range of 0.00040-0.20 {mu}g mL{sup -1} (R=0.99657). The detection limit of NO{sub 2}{sup -} was 0.00010 {mu}g mL{sup -1} (R=0.99657). The method was applied successfully to the determination of nitrite for synthetic samples.

  18. The Sensitivity and Specificity of High Sensitive CRP, D-Dimer and IL-6 in Acute Coronary Syndrome

    Directory of Open Access Journals (Sweden)

    Özlem Yiğit

    2011-11-01

    Full Text Available Objective: ACS is the life threatening causes of chest pain. The aim of this study is to detect the sensitivity and specificity of CRP, IL-6 and D-dimer and identify their role in predicting adverse cardiac events. Material and Methods: All patients describing typical chest pain were enrolled in the study. Demographic features and final diagnosis were written and serum specimens were collected. All patients were telephoned after one month to determine if there were any adverse cardiac events. Results: There were 132 patients, (94 male, 38 female. The mean age was 60.92±10.78. 55 patients were diagnosed as AMI (37 STEMI and 18 NSTEMI 60 patients as unstable angina pectoris, 15 patients as stable angina pectoris and 2 patients as non cardiac chest pain. 6 patients died in the hospital. 15 patients had adverse cardiac events (12 recurrent AMI, 2 sudden cardiac death, 1 stroke. The levels of D-dimer, CRP and IL-6 at the presentation were not predictive for adverse events. Conclusion: D-dimer, CRP and IL-6 levels were high both in ACS and stable angina. Detecting the predictive value for adverse cardiac events requires larger patient numbers and longer follow up times.

  19. Transfer of a two-tiered keratinocyte assay: IL-18 production by NCTC2544 to determine the skin sensitizing capacity and epidermal equivalent assay to determine sensitizer potency

    NARCIS (Netherlands)

    Teunis, M.; Corsini, E.; Smits, M.; Madsen, C.B.; Eltze, T.; Ezendam, J.; Galbiati, V.; Gremmer, E.; Krul, C.A.M.; Landin, A.; Landsiedel, R.; Pieters, R.; Rasmussen, T.F.; Reinders, J.; Roggen, E.; Spiekstra, S.; Gibbs, S.

    2013-01-01

    At present, the identification of potentially sensitizing chemicals is carried out using animal models. However, it is very important from ethical, safety and economic point of view to have biological markers to discriminate allergy and irritation events, and to be able to classify sensitizers accor

  20. Transfer of a two-tiered keratinocyte assay: IL-18 production by NCTC2544 to determine the skin sensitizing capacity and epidermal equivalent assay to determine sensitizer potency

    NARCIS (Netherlands)

    Teunis, M.; Corsini, E.; Smits, M.; Madsen, C.B.; Eltze, T.; Ezendam, J.; Galbiati, V.; Gremmer, E.; Krul, C.A.M.; Landin, A.; Landsiedel, R.; Pieters, R.; Rasmussen, T.F.; Reinders, J.; Roggen, E.; Spiekstra, S.; Gibbs, S.

    2013-01-01

    At present, the identification of potentially sensitizing chemicals is carried out using animal models. However, it is very important from ethical, safety and economic point of view to have biological markers to discriminate allergy and irritation events, and to be able to classify sensitizers

  1. Desensitization protocol in highly HLA-sensitized and ABO-incompatible high titer kidney transplantation.

    Science.gov (United States)

    Uchida, J; Machida, Y; Iwai, T; Naganuma, T; Kitamoto, K; Iguchi, T; Maeda, S; Kamada, Y; Kuwabara, N; Kim, T; Nakatani, T

    2010-12-01

    A positive crossmatch indicates the presence of donor-specific alloantibodies and is associated with a graft loss rate of >80%; anti-ABO blood group antibodies develop in response to exposure to foreign blood groups, resulting in immediate graft loss. However, a desensitization protocol for highly HLA-sensitized and ABO-incompatible high-titer kidney transplantation has not yet been established. We treated 6 patients with high (≥1:512) anti-A/B antibody titers and 2 highly HLA-sensitized patients. Our immunosuppression protocol was initiated 1 month before surgery and included mycophenolate mofetil (1 g/d) and/or low-dose steroid (methylprednisolone 8 mg/d). Two doses of the anti-CD20 antibody rituximab (150 mg/m(2)) were administered 2 weeks before and on the day of transplantation. We performed antibody removal with 6-12 sessions of plasmapheresis (plasma exchange or double-filtration plasmapheresis) before transplantation. Splenectomy was also performed on the day of transplantation. Postoperative immunosuppression followed the same regimen as ABO-compatible cases, in which calcineurin inhibitors were initiated 3 days before transplantation, combined with 2 doses of basiliximab. Of the 8 patients, 7 subsequently underwent successful living-donor kidney transplantation. Follow-up of our recipients showed that the patient and graft survival rates were 100%. Acute cellular rejection and antibody-mediated rejection episodes occurred in 1 of the 7 recipients. These findings suggest that our immunosuppression regimen consisting of rituximab infusions, splenectomy, plasmapheresis, and pharmacologic immunosuppression may prove to be effective as a desensitization protocol for highly HLA-sensitized and ABO-incompatible high-titer kidney transplantation. Copyright © 2010 Elsevier Inc. All rights reserved.

  2. High Steroid Sensitivity among Children with Nephrotic Syndrome in Southwestern Nigeria

    Directory of Open Access Journals (Sweden)

    Taiwo Augustina Ladapo

    2014-01-01

    Full Text Available Recent reports from both Caucasian and black populations suggest changes in steroid responsiveness of childhood nephrotic syndrome. This study was therefore undertaken to determine the features and steroid sensitivity pattern of a cohort of black children with nephrotic syndrome. Records of children managed for nephrotic syndrome from January 2008 to April 2013 were reviewed. Details including age, response to treatment, and renal histology were analysed. There were 108 children (median age: 5.9 years, peak: 1-2 years, 90.2% of whom had idiopathic nephrotic syndrome. Steroid sensitivity was 82.8% among children with idiopathic nephrotic syndrome but 75.9% overall. Median time to remission was 7 days. Median age was significantly lower in steroid sensitive compared with resistant patients. The predominant histologic finding in resistant cases was focal segmental glomerulosclerosis (53.3%. No cases of quartan malaria nephropathy or hepatitis B virus nephropathy were diagnosed. Overall mortality was 6.5%. In conclusion, unusually high steroid sensitivity is reported among a cohort of black children. This is likely attributable to the lower age structure of our cohort as well as possible changing epidemiology of some other childhood diseases. Surveillance of the epidemiology of childhood nephrotic syndrome and corresponding modifications in practice are therefore recommended.

  3. High-pressure studies on the calcium-ion-sensitive fluorophore Fluo-4

    Science.gov (United States)

    Frey, Eric W.; Urayama, Paul

    2007-10-01

    Fluorescence-based methods for intracellular calcium ion sensing are well established at ambient pressure. Because calcium ions play a ubiquitous role in cellular signaling, extending techniques of intracellular calcium-sensing to high pressures would play an important role in understanding the large variety of piezophysiologic effects. Here, we characterize the intracellular calcium-ion-sensitive fluorophore Fluo-4 under hydrostatic pressures up to 500 atm (50 MPa). Using an EGTA/MOPS solution as a calcium-buffer reference, we investigate the pressure dependence of the reaction pK and determine the thermodynamic volume change associated with the Fluo-4 calcium-binding reaction.

  4. Temperature insensitive hysteresis free highly sensitive polymer optical fiber Bragg grating humidity sensor

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Nielsen, Kristian; Stefani, Alessio

    2016-01-01

    sensitivity and a high hysteresis in the humidity response, in particular when operated at high temperature. PMMA mPOFBGs annealed at high humidity show higher and more linear humidity sensitivity with negligible hysteresis. We also report how annealing at high humidity can blue-shift the FBG wavelength more...

  5. Highly sensitive BTX detection using surface functionalized QCM sensor

    Energy Technology Data Exchange (ETDEWEB)

    Bozkurt, Asuman Aşıkoğlu; Özdemir, Okan; Altındal, Ahmet, E-mail: altindal@yildiz.edu.tr [Department of Physics, Yildiz Technical University, Davutpasa, 34210 Istanbul (Turkey)

    2016-03-25

    A novel organic compound was designed and successfully synthesized for the fabrication of QCM based sensors to detect the low concentrations of BTX gases in indoor air. The effect of the long-range electron orbital delocalization on the BTX vapour sensing properties of azo-bridged Pcs based chemiresistor-type sensors have also been investigated in this work. The sensing behaviour of the film for the online detection of volatile organic solvent vapors was investigated by utilizing an AT-cut quartz crystal resonator. It was observed that the adsorption of the target molecules on the coating surface cause a reversible negative frequency shift of the resonator. Thus, a variety of solvent vapors can be detected by using the phthalocyanine film as sensitive coating, with sensitivity in the ppm range and response times in the order of several seconds depending on the molecular structure of the organic solvent.

  6. Highly Sensitive Cadmium Concentration Sensor Using Long Period Grating

    Directory of Open Access Journals (Sweden)

    A. S. Lalasangi

    2011-08-01

    Full Text Available In this paper we have proposed a simple and effective Long Period Grating chemical sensor for detecting the traces of Cadmium (Cd++ in drinking water at ppm level. Long Period gratings (LPG were fabricated by point-by-point technique with CO2 laser. We have characterized the LPG concentration sensor sensitivity for different solutions of Cd concentrations varying from 0.01 ppm to 0.04 ppm by injecting white Light source and observed transmitted spectra using Optical Spectrum Analyzer (OSA. Proper reagents have been used in the solutions for detection of the Cd species. The overall shift in wavelength is 10 nm when surrounding medium gradually changed from water to 0.04 ppm of cadmium concentrations. A comparative study has been done using sophisticated spectroscopic atomic absorption spectrometer (AAS and Inductively Coupled Plasma (ICP instruments. The spectral sensitivity enhancement was done by modifying grating surface with gold nanoparticles.

  7. Determination of new electroweak parameters at the ILC. Sensitivity to new physics

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, M.; Schmidt, E.; Schroeder, H. [Rostock Univ. (Germany). Inst. fuer Physik; Kilian, W. [Siegen Univ. (Gesamthochschule) (Germany). Fach Physik]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Krstonosic, P.; Reuter, J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Moenig, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2006-04-15

    We present a study of the sensitivity of an International Linear Collider (ILC) to electroweak parameters in the absence of a light Higgs boson. In particular, we consider those parameters that have been inaccessible at previous colliders, quartic gauge couplings. Within a generic effective-field theory context we analyze all processes that contain quasi-elastic weak-boson scattering, using complete six-fermion matrix elements in unweighted event samples, fast simulation of the ILC detector, and a multidimensional parameter fit of the set of anomalous couplings. The analysis does not rely on simplifying assumptions such as custodial symmetry or approximations such as the equivalence theorem. We supplement this by a similar new study of triple weak-boson production, which is sensitive to the same set of anomalous couplings. Including the known results on triple gauge couplings and oblique corrections, we thus quantitatively determine the indirect sensitivity of the ILC to new physics in the electroweak symmetry-breaking sector, conveniently parameterized by real or fictitious resonances in each accessible spin/isospin channel. (Orig.)

  8. Environmental context determines community sensitivity of freshwater zooplankton to a pesticide

    Energy Technology Data Exchange (ETDEWEB)

    Stampfli, Nathalie C., E-mail: nathalie.stampfli@ufz.de [Department of System Ecotoxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany); Quantitative Landscape Ecology, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau (Germany); Knillmann, Saskia; Liess, Matthias; Beketov, Mikhail A. [Department of System Ecotoxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig (Germany)

    2011-07-15

    The environment is currently changing worldwide, and ecosystems are being exposed to multiple anthropogenic pressures. Understanding and consideration of such environmental conditions is required in ecological risk assessment of toxicants, but it remains basically limited. In the present study, we aimed to determine how and to what extent alterations in the abiotic and biotic environmental conditions can alter the sensitivity of a community to an insecticide, as well as its recovery after contamination. We conducted an outdoor microcosm experiment in which zooplankton communities were exposed to the insecticide esfenvalerate (0.03, 0.3, and 3 {mu}g/L) under different regimes of solar radiation and community density, which represented different levels of food availability and competition. We focused on the sensitivity of the entire community and analysed it using multivariate statistical methods, such as principal response curves and redundancy analysis. The results showed that community sensitivity varied markedly between the treatments. In the experimental series with the lowest availability of food and strongest competition significant effects of the insecticide were found at the concentration of 0.03 {mu}g/L. In contrast, in the series with relatively higher food availability and weak competition such effects were detected at 3 {mu}g/L only. However, we did not find significant differences in the community recovery rates between the experimental treatments. These findings indicate that environmental context is more important for ecotoxicological evaluation than assumed previously.

  9. Highly sensitive detection using Herriott cell for laser absorption spectroscopy

    Science.gov (United States)

    Zhao, Chongyi; Song, Guangming; Du, Yang; Zhao, Xiaojun; Wang, Wenju; Zhong, Liujun; Hu, Mai

    2016-11-01

    The tunable diode laser absorption spectroscopy combined with the long absorption path technique is a significant method to detect harmful gas. The long optical path could come true by Herriott cell reducing the size of the spectrometers. A 15 cm long Herriott cell with 28.8 m optical absorption path after 96 times reflection was designed that enhanced detection sensitivity of absorption spectroscopy. According to the theory data of calculation, Herriott cell is analyzed and simulated by softwares Matlab and Lighttools.

  10. HIGH SENSITIVE C-REACTIVE PROTEIN IN CEREBROVASCULAR ISCHEMIA

    OpenAIRE

    Padmalatha; Neeraja

    2016-01-01

    BACKGROUND Cerebrovascular ischemia is recognized as a major health problem, which causes significant morbidity and mortality. The main pathophysiology of ischemic stroke is atherosclerosis of cerebral vessels. Hs-CRP is a sensitive marker of inflammation tissue injury in the arterial wall, which contributes to atherosclerosis. In this study, we aim to investigate the association of hs-CRP in patients with ischemic stroke and to correlate hs-CRP levels with possible risk facto...

  11. The strain-rate sensitivity of high-strength high-toughness steels.

    Energy Technology Data Exchange (ETDEWEB)

    Dilmore, M.F. (AFRL/MNMW, Eglin AFB, FL); Crenshaw, Thomas B.; Boyce, Brad Lee

    2006-01-01

    The present study examines the strain-rate sensitivity of four high strength, high-toughness alloys at strain rates ranging from 0.0002 s-1 to 200 s-1: Aermet 100, a modified 4340, modified HP9-4-20, and a recently developed Eglin AFB steel alloy, ES-1c. A refined dynamic servohydraulic method was used to perform tensile tests over this entire range. Each of these alloys exhibit only modest strain-rate sensitivity. Specifically, the strain-rate sensitivity exponent m, is found to be in the range of 0.004-0.007 depending on the alloy. This corresponds to a {approx}10% increase in the yield strength over the 7-orders of magnitude change in strain-rate. Interestingly, while three of the alloys showed a concominant {approx}3-10% drop in their ductility with increasing strain-rate, the ES1-c alloy actually exhibited a 25% increase in ductility with increasing strain-rate. Fractography suggests the possibility that at higher strain-rates ES-1c evolves towards a more ductile dimple fracture mode associated with microvoid coalescence.

  12. Sensitive voltammetric determination of vanillin with an AuPd nanoparticles-graphene composite modified electrode.

    Science.gov (United States)

    Shang, Lei; Zhao, Faqiong; Zeng, Baizhao

    2014-05-15

    In this work, graphene oxide was reduced to graphene with an endogenous reducing agent from dimethylformamide, and then AuPd alloy nanoparticles were electrodeposited on the graphene film. The obtained AuPd-graphene hybrid film was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and voltammetry. The electrochemical behavior of vanillin was studied using the AuPd-graphene hybrid based electrode. It presented high electrocatalytic activity and vanillin could produce a sensitive oxidation peak at it. Under the optimal conditions, the peak current was linear to the concentration of vanillin in the ranges of 0.1-7 and 10-40 μM. The sensitivities were 1.60 and 0.170 mA mM(-1) cm(-2), respectively; the detection limit was 20 nM. The electrode was successfully applied to the detection of vanillin in vanilla bean, vanilla tea and biscuit samples.

  13. Sensitive and direct determination of lithium by mixed-mode chromatography and charged aerosol detection.

    Science.gov (United States)

    Dai, Lulu; Wigman, Larry; Zhang, Kelly

    2015-08-21

    A sensitive analytical method using mixed mode HPLC separation coupled with charged aerosol detection (CAD) was developed for quantitative analysis of lithium. The method is capable of separating lithium ion from different drug matrices and other ions in a single run thus eliminating the organic matrix and ionic analyte interferences without extensive sample preparation such as derivatization and extraction. The separation space and chromatographic conditions are defined by systematic studies of the retention behaviors of lithium and potential interfering ions and different type of pharmaceutical APIs (active pharmaceutical ingredients) under reversed-phase, HILIC and cation/anion exchange mechanisms. Compared to other current analytical techniques for lithium analysis, the presented method provides a new approach and demonstrates high sensitivity (0.02ng for LOD and 0.08ng for LOQ in both standard and sample solution). The method has been validated for pharmaceutical samples and can be potentially applied to biological, food and environmental samples.

  14. A sensitive spectrofluorimetric method for the determination of ranitidine hydrochloride in pharmaceutical preparation

    Science.gov (United States)

    Ulu, Sevgi Tatar; Çakar, Mahmut Bülent

    2012-08-01

    A simple, precise and sensitive spectrofluorimetric method was developed and validated for the determination of ranitidine in pharmaceutical preparations. The method is based on derivatization of ranitidine with 4-fluoro-7-nitrobenzofurazan (NBD-F). The method was successfully validated in accordance to ICH guidelines. The validation characteristics included linearity, limit of detection, limit of quantification, accuracy, precision, specificity and robustness. The method is linear over the range of 40-1200 ng/mL. The recoveries were ranged from 98.97 to 99.43%. The proposed method was applied for the determination of ranitidine in commercially available tablets. The results were compared with those obtained by reference method using t and F-tests.

  15. Cadmium telluride quantum dots as pH-sensitive probes for tiopronin determination

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yunqing; Ye Chao; Zhu Zhenghui [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China); Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Hu Yuzhu [Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009 (China) and Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009 (China)], E-mail: njhuyuzu@126.com

    2008-03-03

    The pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) were used as proton probes for tiopronin determination. Based on the fluorescence quenching of CdTe QDs caused by tiopronin, a simple, rapid and specific quantitative method was proposed. Under the optimal conditions, the calibration plot of ln(F{sub 0}/F) with concentration of tiopronin was linear in the range of 0.15-20 {mu}g mL{sup -1}(0.92-122.5 {mu}mol L{sup -1}) with correlation coefficient of 0.998. The limit of detection (LOD) (3{sigma}/k) was 0.15 {mu}g mL{sup -1}(0.92 {mu}mol mL{sup -1}). The content of tiopronin in pharmaceutical tablet was determined by the proposed method and the result agreed with that obtained from the oxidation-reduction titration method and the claimed value.

  16. Terbium-sensitized luminescence optosensor for the determination of norfloxacin in biological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, E.J. Llorent [Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaen, Paraje Las Lagunillas, E-23071 Jaen (Spain); Reyes, J.F. Garcia [Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaen, Paraje Las Lagunillas, E-23071 Jaen (Spain); Barrales, P. Ortega [Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaen, Paraje Las Lagunillas, E-23071 Jaen (Spain); Diaz, A. Molina [Department of Physical and Analytical Chemistry, Faculty of Experimental Sciences, University of Jaen, Paraje Las Lagunillas, E-23071 Jaen (Spain)]. E-mail: amolina@ujaen.es

    2005-03-14

    The use of a flow through solid phase terbium-sensitized luminescence system is described for the determination of the widely used fluoroquinolone norfloxacin. A chelate between the terbium ion and the analyte is formed online previously to the sample injection into the carrier stream. Then the chelate is transported towards the flow-through cell, where it is retained on a cationic Sephadex resin packed in the cell, developing the corresponding luminescence signal. Afterwards, an ethylenediaminetetraacetic acid solution was used as eluting agent, in order to regenerate the sensing zone. The system has been satisfactorily applied to the determination of norfloxacin in human urine and serum, without the need of a pre-treatment. The response was linear in the range 10-150 ng ml{sup -1}. The detection and quantification limits were 1.5 and 5 ng ml{sup -1}, respectively and the R.S.D. 1.82%.

  17. Sensitive determination of bromazepam in human tissues using capillary gas chromatography-mass spectrometry.

    Science.gov (United States)

    Zhang, X X; Kudo, K; Imamura, T; Jitsufuchi, N; Nagata, T

    1996-02-23

    A reliable and sensitive gas chromatographic-mass spectrometric method was devised to determine the levels of bromazepam in human tissues. Bromazepam was extracted from body tissues using a three-step solvent extraction procedure. N-Desmethyldiazepam served as the internal standard. Selected ion monitoring with m/z 317 for bromazepam and m/z 270 for internal standard was used for quantitation. Calibration curves in all body tissues were linear over the concentration range from 50-500 ng/g. The lower detection limit in body tissues was 2-5 ng/g and the absolute recovery in body tissues was 27.8-68.0%. This method was used to determine the levels of bromazepam in tissues of an autopsied individual who had been prescribed psychotropic drugs and who was found dead in a car.

  18. Sensitive method of determination of gold (III using diacetyl monoxime isonicotinoyl hydrazone (DMIH

    Directory of Open Access Journals (Sweden)

    Gadikota Chandrasekhar Reddy

    2011-12-01

    Full Text Available Gold (III forms a yellow coloured water soluble complex with diacetyl monoxime isonicotinoyl hydrazone (DMIH reagent in acidic buffer pH 4.5 with ?max at 361 nm. The molar absorptivity and Sandell’s sensitivity are 1.50X10 4 L .mol -1.cm-1 and 0.00333 µg/cm2, respectively .The Beer’s law validity range is 0.985–11.82 µg/mL. The optimum concentration range is 1.97-9.85 µg/mL. Gold (III forms (M:L 1:1 complex with DMIH and stability constant of the complex is 3.263X106. The derivative spectrophotometric determination of Au (III was carried out by measuring peak height method. The developed derivative spectrophotometric method was employed for the determination of gold (III in synthetic alloy samples. The effect of various diverse ions was also studied.

  19. Determination of atropine using Mn-doped ZnS quantum dots as novel luminescent sensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Azizi, Seyed Naser [Analytical Division, Faculty of Chemistry, University of Mazandaran, Babolsar 4741695447 (Iran, Islamic Republic of); Chaichi, Mohammad Javad, E-mail: jchaichi@yahoo.com [Analytical Division, Faculty of Chemistry, University of Mazandaran, Babolsar 4741695447 (Iran, Islamic Republic of); Shakeri, Parmis [Analytical Division, Faculty of Chemistry, University of Mazandaran, Babolsar 4741695447 (Iran, Islamic Republic of); Bekhradnia, Ahmadreza [Pharmaceutical Sciences Research Center, Department of Medicinal Chemistry, Mazandaran University of Medical Sciences, Sari (Iran, Islamic Republic of)

    2013-12-15

    A novel chemiluminescence (CL) method using water-soluble Mn-doped ZnS quantum dots (QDs) as sensitizers is proposed for the chemiluminometric determination of atropine in pharmaceutical formulation. Water-soluble Mn-doped ZnS QDs were synthesized by using L-cysteine as stabilizer in aqueous solutions. The nanoparticles were structurally and optically characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV–vis absorption spectroscopy and photoluminescence (PL) emission spectroscopy. It was found that ZnS quantum dots acted as enhancers of the weak CL emission produced upon oxidation of sulfite by Ce(IV) in acidic medium. Trace amounts of atropine improved the sensitize effect of ZnS quantum dots yielding a significant chemiluminescence enhancement of the Ce(IV)–SO{sub 3}{sup 2−}–ZnS QD system. Therefore, a new CL analysis system was developed for the determination of atropine. Under the optimum conditions, there is a good linear relationship between the relative chemiluminescence intensity and the concentration of atropine in the range of 1×10{sup −9}–1×10{sup −6} M of atropine with a correlation coefficient (R{sup 2}) of 0.9992. The limit of detection of this system was found to be 2.54×10{sup −10} M. This method is not only simple, sensitive and low cost, but also reliable for practical applications. -- Highlights: • Mn-doped ZnS quantum dots could enhance the chemiluminescence (CL) of cerium(IV)–sodium sulfite system. • ZnS quantum dots were used as the nanocatalyst. • Trace amounts of atropine improved the sensitize effect of ZnS quantum dots. • This work is introduced as a new method for the determination of atropine commercial drugs. • Detection limit of atropine was obtained 2.54×10{sup −10} mol L{sup −1}.

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

    Science.gov (United States)

    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.

  1. A high sensitivity field effect transistor biosensor for methylene blue detection utilize graphene oxide nanoribbon.

    Science.gov (United States)

    Lin, Ting-Chun; Li, Yan-Sheng; Chiang, Wei-Hung; Pei, Zingway

    2017-03-15

    In this work, we developed a field effect transistor (FET) biosensor utilizing solution-processed graphene oxide nanoribbon (GONR) for methylene blue (MB) sensing. MB is a unique material; one of its crucial applications is as a marker in the detection of biomaterials. Therefore, a highly sensitive biosensor with a low detection limit that can be fabricated simply in a noncomplex detection scheme is desirable. GONR is made by unzipping multiwall carbon nanotubes, which can be mass-produced at low temperature. The GONR-FET biosensor demonstrated a sensitivity of 12.5μA/mM (determined according to the drain current difference caused by the MB concentration change). The Raman spectra indicate that the materials quality of the GONR and the domain size for the C=C sp(2) bonding were both improved after MB detection. X-ray photoelectron spectroscopy revealed that the hydroxyl groups on the GONR were removed by the reductive MB. According to XPS and Raman, the positive charge is proposed to transfer from MB to GONR during sensing. This transfer causes charge in-neutrality in the GONR which is compensated by releasing •OH functional groups. With high sensitivity, a low detection limit, and a simple device structure, the GONR-FET sensor is suitable for sensing biomaterials.

  2. [High-sensitivity troponin in patients with stable coronary artery disease].

    Science.gov (United States)

    van 't Hof, Arnoud W J

    2015-01-01

    With the introduction of more sensitive markers of myocardial necrosis, it was shown that the diagnosis of (acute) myocardial infarction could be improved. However, many patients without myocardial infarction have elevated troponin levels (low sensitivity), resulting in additional diagnostic testing and longer admission times to find the cause of the troponin rise. Elevated troponin levels in these patients were found to have limited diagnostic but strong prognostic value. This led to studies assessing the value of high-sensitivity troponin in patients with stable disease, e.g. coronary artery disease, or even in patients without apparent (clinical) disease. These studies consistently showed a strong association with long-term (cardiac) mortality. What is the value for the general physician in daily practice? Although troponin levels may help in finding (healthy?) patients at higher risk, it remains unclear whether interventions (medication, lifestyle) are more (cost-)effective in this high-risk subgroup. The role of troponin levels as a prognostic marker in stable patients therefore remains to be determined.

  3. Determination of CO₂ sensitivity of micro-organisms in shaken bioreactors. II. Novel online monitoring method.

    Science.gov (United States)

    Amoabediny, Ghassem; Abbas, Mahdi Pesaran Haji; Büchs, Jochen

    2010-12-01

    In the present study, a new online monitoring method for the determination of the CO₂ sensitivity of micro-organisms, based on the values of the respiration factors [OTR (oxygen transfer rate) and CTR (carbon dioxide transfer rate)], obtained by using the RAMOS (respiratory activity monitoring system) device considering a variety of aeration rates in the measuring flask, is investigated. Based on the data of the OTR, obtained by RAMOS under a variety of specific aeration rates, the proposed new method was developed as an online monitoring method for CO₂ sensitivity of micro-organisms in shaken bioreactors. A maximum accumulated CO₂ concentration of 12% was derived in applied methods, provided that the cultivation system is carried out under optimal conditions. Additionally, to predict these conditions, an unsteady-state gas transfer model in shaken bioreactors would be very advantageous. The data of OTR obtained using the RAMOS device were analysed and recalculated by a programme considering the calibration factor (Cf). The major advantage of the new method is the possibility to determine the metabolic activity, regardless of manual sampling.

  4. The Significance of Ultrasound in Determining Whether SHPT Patients Are Sensitive to Calcitriol Treatment

    Directory of Open Access Journals (Sweden)

    Xing-xin Liang

    2016-01-01

    Full Text Available This study was to explore the significance of ultrasound in determining whether the patients with secondary hyperparathyroidism (SHPT are sensitive to calcitriol treatment. According to the decrease value of parathyroid hormone (PTH, 42 SHPT patients were divided into two groups: drug susceptible group and drug insusceptible group. These 42 SHPT patients’ ultrasound images were retrospectively analyzed. The morphology, size, number, blood flow, elastic modulus, and perfusion of the parathyroid glands were correlated with drug therapeutic outcome (oral calcitriol. Most SHPT patients with drug susceptible showed volume <438.50 mm3 and number ≤2, with 0-1 structural and vascular patterns, associated with Relative Maximum Intensity (RIMAX <1.59 and elastic modulus <18.8 kPa, whereas most SHPT patients with drug insusceptible showed volume ≥438.50 mm3 and number ≥3, with 2-3 structural and vascular patterns, associated with Relative Maximum Intensity (RIMAX ≥1.59 and elastic modulus ≥18.8 kPa. Therefore, ultrasonography in SHPT allows an accurate definition of the morphology, size, number, blood flow, elastic modulus, and perfusion of the parathyroid glands and is useful in determining whether SHPT patients are sensitive to calcitriol treatment.

  5. Sensitive Determination of Sertraline in Commercial Drugs and Its Stability Check in Simulated Gastric Juice.

    Science.gov (United States)

    Koçoğlu, Elif Seda; Bakırdere, Sezgin; Keyf, Seyfullah

    2016-11-01

    A sensitive analytical method was developed for the determination of sertraline in commercial drug samples by using GC-MS. The selected-ion monitoring mode was used at the most sensitive m/z 274 to obtain a lower detection limit. LOD/LOQ values were obtained as 1.6/5.4 ng/mL for sertraline under the optimum conditions. The calibration plot was linear between 5.0 and 2000 ng/mL with the correlation coefficient of 0.9999. The validated method was successfully applied to three different brands of drug samples for both qualitative and quantitative measurement of sertraline. In this experiment, four replicate extractions were performed for each brand, and the results were compared to the values written on the labels of the drug brands. Spiking experiments were also performed to check the effect of the matrixes on the determination, and it was observed that there was no shift in the retention time of the analyte. In addition, simulated gastric juice experiments were performed to check the stability of sertraline in the stomach for 240 min, and it was observed that there was no change in the structure of the analyte.

  6. Two-tiered keratinocyte assay: IL-18 production by NCTC2544 cells to determine the skin sensitizing capacity and an epidermal equivalent assay to determine sensitizer potency

    DEFF Research Database (Denmark)

    Teunis, Marc; Corsini, Emanuela; Smits, Mieke

    2012-01-01

    method to the LLNA. Both assays are based on the use of human keratinocytes, which have been shown, over the last two decades, to play a key role in all phases of skin sensitization. First, 4 known chemicals were tested during a transferability study in which 6 laboratories participated. Three......At present, the identification of potentially sensitizing chemicals is carried out using animal models. However, it should be very important, both from ethical and economic point of view, to discriminate allergy and irritation events, and to classify sensitizers according to their potency, without...... the use of animals. The aim of the EU FP6 Integrated Project Sens-it-iv was to develop and optimize an integrated testing strategy consisting of in vitro, human cell based assays which will closely mimic sensitization mechanisms in vivo. These assays should be an alternative approach to the LLNA. The NCTC...

  7. Ex vivo stimulation of whole blood as a means to determine glucocorticoid sensitivity

    Directory of Open Access Journals (Sweden)

    Burnsides C

    2012-08-01

    Full Text Available Christopher Burnsides,1,* Jacqueline Corry,1,* Jacob Alexander,1 Catherine Balint,1 David Cosmar,1 Gary Phillips,2 Jeanette I Webster Marketon1,31Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Internal Medicine, 2Center for Biostatistics, 3Institute for Behavioral Medicine Research, Wexner Medical Center at The Ohio State University, Columbus, OH, USA*JC and CB have equally contributed to this workPurpose: Glucocorticoids are commonly prescribed to treat a number of diseases including the majority of inflammatory diseases. Despite considerable interpersonal variability in response to glucocorticoids, an insensitivity rate of about 30%, and the risk of adverse side effects of glucocorticoid therapy, currently no assay is performed to determine sensitivity.Patients and methods: Here we propose a whole blood ex vivo stimulation assay to interrogate known glucocorticoid receptor (GR up- and downregulated genes to indicate glucocorticoid sensitivity. We have chosen to employ real-time PCR in order to provide a relatively fast and inexpensive assay.Results: We show that the GR-regulated genes, GILZ and FKBP51, are upregulated in whole blood by treatment with dexamethasone and that LPS-induction of cytokines (IL-6 and TNFα are repressed by dexamethasone in a dose responsive manner. There is considerable interpersonal variability in the maximum induction of these genes but little variation in the EC50 and IC50 concentrations. The regulation of the GR-induced genes differs throughout the day whereas the suppression of LPS-induced cytokines is not as sensitive to time of day.Conclusion: In all, this assay would provide a method to determine glucocorticoid receptor responsiveness in whole blood.Keywords: glucocorticoid responsiveness, gene regulation, nuclear receptor, GILZ, FKBP51, cytokines

  8. High-performance and high-sensitivity applications of graphene transistors with self-assembled monolayers.

    Science.gov (United States)

    Yeh, Chao-Hui; Kumar, Vinod; Moyano, David Ricardo; Wen, Shao-Hsuan; Parashar, Vyom; Hsiao, She-Hsin; Srivastava, Anchal; Saxena, Preeti S; Huang, Kun-Ping; Chang, Chien-Chung; Chiu, Po-Wen

    2016-03-15

    Charge impurities and polar molecules on the surface of dielectric substrates has long been a critical obstacle to using graphene for its niche applications that involve graphene's high mobility and high sensitivity nature. Self-assembled monolayers (SAMs) have been found to effectively reduce the impact of long-range scatterings induced by the external charges. Yet, demonstrations of scalable device applications using the SAMs technique remains missing due to the difficulties in the device fabrication arising from the strong surface tension of the modified dielectric environment. Here, we use patterned SAM arrays to build graphene electronic devices with transport channels confined on the modified areas. For high-mobility applications, both rigid and flexible radio-frequency graphene field-effect transistors (G-FETs) were demonstrated, with extrinsic cutoff frequency and maximum oscillation frequency enhanced by a factor of ~2 on SiO2/Si substrates. For high sensitivity applications, G-FETs were functionalized by monoclonal antibodies specific to cancer biomarker chondroitin sulfate proteoglycan 4, enabling its detection at a concentration of 0.01 fM, five orders of magnitude lower than that detectable by a conventional colorimetric assay. These devices can be very useful in the early diagnosis and monitoring of a malignant disease.

  9. A rapid electrochemical monitoring platform for sensitive determination of thiamethoxam based on β-cyclodextrin-graphene composite.

    Science.gov (United States)

    Zhai, XingChen; Zhang, Hua; Zhang, Min; Yang, Xin; Gu, Cheng; Zhou, GuoPeng; Zhao, HaiTian; Wang, ZhenYu; Dong, AiJun; Wang, Jing

    2017-01-20

    A rapid monitoring platform for sensitive voltammetric detection of thiamethoxam residues is reported in the present study. A β-cyclodextrin-reduced graphene oxide composite was used as a reinforcing material in electrochemical determination of thiamethoxam. Compared with bare glassy carbon electrodes, the reduction peak currents of thiamethoxam at reduced graphene oxide/glassy carbon electrode and β-cyclodextrin-reduced graphene oxide/glassy carbon electrode were increased by 70- and 124-fold, respectively. The experimental conditions influencing voltammetric determination of thiamethoxam, such as the amount of β-cyclodextrin-reduced graphene oxide, solution pH, temperature, and accumulation time, were optimized. The reduction mechanism and binding affinity of this material is also discussed. Under optimal conditions, the reduction peak currents increased linearly between 0.5 µM and 16 µM concentration of thiamethoxam. The limit of detection was 0.27 µM on the basis of a signal-to-noise ratio of 3. When the proposed method was applied to brown rice in a recovery test, the recoveries were between 92.20% and 113.75%. The results were in good concordance with the high-performance liquid chromatography method. The proposed method therefore provides a promising and effective platform for sensitive and rapid determination of thiamethoxam. Environ Toxicol Chem 2017;9999:1-7. © 2017 SETAC.

  10. Design and calibration of a high-sensitivity and high-accuracy polarimeter based on liquid crystal variable retarders

    Science.gov (United States)

    Guo, Jing; Ren, De-Qing; Liu, Cheng-Chao; Zhu, Yong-Tian; Dou, Jiang-Pei; Zhang, Xi; Beck, Christian

    2017-01-01

    Polarimetry plays an important role in the measurement of solar magnetic fields. We developed a high-sensitivity and high-accuracy polarimeter (HHP) based on nematic liquid crystal variable retarders (LCVRs), which has a compact setup and no mechanical moving parts. The system design and calibration methods are discussed in detail. The azimuth error of the transmission axis of the polarizer as well as the fast axes of the two LCVRs and the quarter-wave plate were determined using dedicated procedures. Linearly and circularly polarized light were employed to evaluate the performance of the HHP. The experimental results indicate that a polarimetric sensitivity of better than \\[5.7 × {10 - 3}\\] can be achieved by using a single short-exposure image, while an accuracy on the order of 10‑5 can be reached by using a large number of short-exposure images. This makes the HHP a high-performance system that can be used with a ground-based solar telescope for high-precision solar magnetic field investigations.

  11. Highly sensitive method for diagnosis of subclinical B. ovis infection.

    Science.gov (United States)

    Horta, Sara; Barreto, Maria C; Pepe, Ana; Campos, Joana; Oliva, Abel

    2014-10-01

    Babesia ovis is a tick-transmitted protozoa parasite that infects small ruminants causing fever, anaemia, hemoglobinuria, anorexia and, in acute cases, death. Common in tropical and sub-tropical areas, the presence of this parasite in sheep herds has an economic impact on industry and therefore sensitive methods for the diagnosis and disease eradication are required. To achieve this goal, a semi-nested PCR for B. ovis specific identification was developed and consequent reaction conditions and enzymes were optimized and tested with field samples. 300 blood samples from small ruminants and 39 ticks from Rhipicephalus genus were collected from different regions of Portugal. Afterwards, DNA extraction was performed and conventional and semi-nested PCR were accomplished for all samples. The results obtained from both methodologies were compared and the sensitivity was evaluated. Employing the semi-nested PCR it was possible to identify a higher number of positive cases among the evaluated samples than using the conventional PCR, namely 38/300 blood samples and 7/39 ticks. However, fragment amplification was only observed in 5 out of 300 blood samples and in none of the 39 ticks when a conventional PCR was employed. The validation of the results was achieved by sequencing the DNA fragments corresponding to the hypervariable v4 region of the 18S ribosomal RNA gene and performing an alignment with sequences already published on GenBank(®). The ticks collected in this study belong to the Rhipicephalus genus, although other species could be involved as a vector in the Babesia spread. The diagnostic assay here described is presently the most effective and sensitive method for detection of B. ovis in field blood samples and ticks, enabling the detection up to 1 parasite into 10(9) erythrocytes. Copyright © 2014 Elsevier GmbH. All rights reserved.

  12. HIGHLY SENSITIVE TIMER-BASED RESISTANCE DEVIATION TO TIME CONVERTER

    Directory of Open Access Journals (Sweden)

    Sheroz Khan

    2012-02-01

    Full Text Available Based on an inexpensive popular precision timing chip 555 timer, a resistance to time converter is proposed in this paper which is indeed capable of converting resistive and capacitive changes into pulse widths of proportional durations. This converter exhibits a compatibility of wider conversion range with a reasonable level of sensitivity required for industrial applications. The circuit is expected to have utility in oil and water supply schemes. Simulated results are shown to be compared with mathematical derivations, both reporting a good level of resemblance and similarities.

  13. High order sensitivity analysis of complex, coupled systems

    Science.gov (United States)

    Sobieszczanski-Sobieski, Jaroslaw

    1990-01-01

    The Sobieszczanski-Sobieski (1988) algorithm is extended to include second- and higher-order derivatives while retaining the obviation of finite-differencing of the system analysis. This is accomplished by means of a recursive application of the same implicit function theorem as in the original algorithm. In optimization, the computational cost of the higher-order derivatives is relative to the aggregate cost of analysis together with a repetition of the first-order sensitivity analysis as often as is required to produce the equivalent information by successive linearizations within move limits.

  14. High Sensitivity TSS Prediction: Estimates of Locations Where TSS Cannot Occur

    KAUST Repository

    Schaefer, Ulf

    2013-10-10

    Background Although transcription in mammalian genomes can initiate from various genomic positions (e.g., 3′UTR, coding exons, etc.), most locations on genomes are not prone to transcription initiation. It is of practical and theoretical interest to be able to estimate such collections of non-TSS locations (NTLs). The identification of large portions of NTLs can contribute to better focusing the search for TSS locations and thus contribute to promoter and gene finding. It can help in the assessment of 5′ completeness of expressed sequences, contribute to more successful experimental designs, as well as more accurate gene annotation. Methodology Using comprehensive collections of Cap Analysis of Gene Expression (CAGE) and other transcript data from mouse and human genomes, we developed a methodology that allows us, by performing computational TSS prediction with very high sensitivity, to annotate, with a high accuracy in a strand specific manner, locations of mammalian genomes that are highly unlikely to harbor transcription start sites (TSSs). The properties of the immediate genomic neighborhood of 98,682 accurately determined mouse and 113,814 human TSSs are used to determine features that distinguish genomic transcription initiation locations from those that are not likely to initiate transcription. In our algorithm we utilize various constraining properties of features identified in the upstream and downstream regions around TSSs, as well as statistical analyses of these surrounding regions. Conclusions Our analysis of human chromosomes 4, 21 and 22 estimates ~46%, ~41% and ~27% of these chromosomes, respectively, as being NTLs. This suggests that on average more than 40% of the human genome can be expected to be highly unlikely to initiate transcription. Our method represents the first one that utilizes high-sensitivity TSS prediction to identify, with high accuracy, large portions of mammalian genomes as NTLs. The server with our algorithm implemented is

  15. Micelle enhanced and native spectrofluorimetric methods for determination of sertindole using sodium dodecyl sulfate as sensitizing agent.

    Science.gov (United States)

    El-Kosasy, Amira M; Hussein, Lobna A; Sedki, Nehal G; Salama, Nahla N

    2016-01-15

    Two stability indicating spectrofluorimetric methods were developed and validated for the determination of sertindole (SER) in the presence of its acid and oxidative degradates at λ(ex) 257 nm and λ(em) 335 nm. Method A was based on measuring the native fluorescence of SER using isopropanol as solvent. Method B was based on the enhancement of native fluorescence of SER quenched in aqueous media by using micellar microenvironment created by sodium dodecyl sulfate (SDS) anionic micelles using Britton Robinson Buffer (BRB) pH3.29 as solvent. Different factors affecting fluorescence intensity; both native and enhanced, were carefully studied to reach the optimum conditions of measurements. The proposed spectrofluorimetric methods were validated in accordance with ICH guidelines and were successfully applied for the determination of SER in bulk powder and pharmaceutical preparation with high sensitivity and stability indicating power. They were also statistically compared to the manufacturer methods with no significant difference in performance.

  16. Development of a high sensitive MEMS hydrophone using PVDF

    Science.gov (United States)

    Varadan, Vijay K.; Zhu, Bei; K. A, Jose

    2002-05-01

    The design and experimental evaluation of a PVDF-based MEMS hydrophone is presented in this paper. The basic structure of the hydrophone was fabricated on a silicon wafer using standard NMOS process technology. A MOSFET with extended gate electrode was designed as the interface circuit to the sensing material, which is a piezoelectric polymer, polyvinylidene difluoride (PVDF). Acoustic impedance possessed by this piezoelectric material provides a reasonable match to water, which makes it very attractive for underwater applications. The electrical signal generated by the PVDF film was directly coupled to the gate of the MOSFET. To minimize the parasitic capacitance underneath the PVDF film and hence improve the device sensitivity, a thick photoresist was first employed as the dielectric layer under the extended gate electrode. For underwater operation, a waterproof Rho-C rubber encapsulated the hydrophone. A silicon nitride layer passivated the active device, which is a good barrier material to most mobile ions and solvents. The device after passivation also shows a lower noise level. The theoretical model developed to predict the sensitivity of the hydrophone shows a reasonable agreement between the theory and the experiment.

  17. Photothermal Microscopy for High Sensitivity and High Resolution Absorption Contrast Imaging of Biological Tissues

    Directory of Open Access Journals (Sweden)

    Jun Miyazaki

    2017-04-01

    Full Text Available Photothermal microscopy is useful to visualize the distribution of non-fluorescence chromoproteins in biological specimens. Here, we developed a high sensitivity and high resolution photothermal microscopy with low-cost and compact laser diodes as light sources. A new detection scheme for improving signal to noise ratio more than 4-fold is presented. It is demonstrated that spatial resolution in photothermal microscopy is up to nearly twice as high as that in the conventional widefield microscopy. Furthermore, we demonstrated the ability for distinguishing or identifying biological molecules with simultaneous muti-wavelength imaging. Simultaneous photothermal and fluorescence imaging of mouse brain tissue was conducted to visualize both neurons expressing yellow fluorescent protein and endogenous non-fluorescent chromophores.

  18. Characterization of a new highly sensitive immunometric assay for thyroglobulin with reduced interference from autoantibodies.

    Science.gov (United States)

    Broughton, Marianne Nordlund; Nome, Ragnhild; Sandven, Ingvill; Paus, Elisabeth; Bjøro, Trine

    2016-06-01

    Measurements of serum thyroglobulin (Tg) with sensitive immunoassays are of great importance for the management of patients with differentiated thyroid carcinomas. However, interference of circulating autoantibodies to Tg (hTgAb) hampers the usefulness of most assays. We have produced a panel of monoclonal antibodies (mAbs) selected to bind Tg in the presence of Tg autoantibodies and developed a sensitive immunoassay for Tg with minor interference by hTgAbs. The antibodies were characterized by cross-inhibition and immunoassay combination studies, as well as affinity estimation. The within-run and total imprecision of the assay were determined with 2664 samples in 60 separate runs. The most sensitive assay combination with superior protection against autoantibodies consisted of two solid phase mAbs and two tracer mAbs with distinct binding sites. The assay was linear and displayed a wide dynamic range up to 1342 μg/l with a functional sensitivity of 0.1 μg/l and a total imprecision of less than 10 %. There was good agreement between the new high sensitive immunofluorometric assay (IFMA) and two well-established Tg assays from Brahms Kryptor and Roche Diagnostics. Mean difference between the new IFMA and the Kryptor assay was 0.059 μg/l with a 95 % confidence interval of -0.032 to 0.151 μg/l, whereas the mean difference between the new IFMA and the Roche assay was -0.80 μg/l with a 95 % confidence interval of -1.24 to -0.35 μg/l.

  19. Edge sensitivity of “edgeless” silicon pad detectors measured in a high-energy beam

    Science.gov (United States)

    Perea Solano, B.; Abreu, M. C.; Avati, V.; Boccali, T.; Boccone, V.; Bozzo, M.; Capra, R.; Casagrande, L.; Chen, W.; Eggert, K.; Heijne, E.; Klauke, S.; Li, Z.; Mäki, T.; Mirabito, L.; Morelli, A.; Niinikoski, T. O.; Oljemark, F.; Palmieri, V. G.; Rato Mendes, P.; Rodrigues, S.; Siegrist, P.; Silvestris, L.; Sousa, P.; Tapprogge, S.; Trocmé, B.

    2005-09-01

    We report measurements in a high-energy beam of the sensitivity of the edge region in “edgeless” planar silicon pad diode detectors. The edgeless side of these rectangular diodes is formed by a cut and break through the contact implants. A large surface current on such an edge prevents the normal reverse biasing of this device above the full depletion voltage, but we have shown that the current can be sufficiently reduced by the use of a suitable cutting method, followed by edge treatment, and by operating the detector at a low temperature. A pair of these edgeless silicon diode pad sensors was exposed to the X5 high-energy pion beam at CERN, to determine the edge sensitivity. The signal of the detector pair triggered a reference telescope made of silicon microstrip detector modules. The gap width between the edgeless sensors, determined using the tracks measured by the reference telescope, was then compared with the results of precision metrology. It was concluded that the depth of the dead layer at the diced edge is compatible with zero within the statistical precision of ±8 μm and systematic error of ±6 μm.

  20. High temperature probe sensor with high sensitivity based on Michelson interferometer

    Science.gov (United States)

    Zhao, Na; Fu, Haiwei; Shao, Min; Yan, Xu; Li, Huidong; Liu, Qinpeng; Gao, Hong; Liu, Yinggang; Qiao, Xueguang

    2015-05-01

    A novel Michelson interferometer based on a bi-taper is achieved. Such a device is fabricated by splicing a section of thin core fiber (TCF) at one end of single-mode fiber (SMF). Due to the fiber bi-taper at the splicing point of SMF and TCF, the light is coupled into the fiber core and cladding from lead in fiber core. The light will be reflected at the end of the fiber and then will be recoupled back into the lead out fiber core by the fiber bi-taper. While the light returns back to the lead out fiber, the intermodal interference will occur for the optical path difference between core mode and cladding mode. A high temperature sensitivity of 0.140 nm/°C is achieved from 30 to 800 °C, and the linearity is 99.9%. The configuration features the advantages of easy fabrication, a compact size, high sensitivity, wide sensing range and high mechanical strength, making it a good candidate for distant temperature sensing and oil prospecting.

  1. Highly sensitive methods for electroanalytical chemistry based on nanotubule membranes.

    Science.gov (United States)

    Kobayashi, Y; Martin, C R

    1999-09-01

    Two new methods of electroanalysis are described. These methods are based on membranes containing monodisperse Au nanotubules with inside diameters approaching molecular dimensions. In one method, the analyte species is detected by measuring the change in trans-membrane current when the analyte is added to the nanotubule-based cell. The second method entails the use of a concentration cell based on the nanotubule membrane. In this case, the change in membrane potential is used to detect the analyte. Detection limits as low as 10(-11) M have been achieved. Hence, these methods compete with even the most sensitive of modern analytical methodologies. In addition, excellent molecular-sized-based selectivity is observed.

  2. A new compact, high sensitivity neutron imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Caillaud, T.; Landoas, O.; Briat, M.; Rosse, B.; Thfoin, I.; Philippe, F.; Casner, A.; Bourgade, J. L.; Disdier, L. [CEA, DAM, DIF,F-91297 Arpajon (France); Glebov, V. Yu.; Marshall, F. J.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Park, H. S.; Robey, H. F.; Amendt, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2012-10-15

    We have developed a new small neutron imaging system (SNIS) diagnostic for the OMEGA laser facility. The SNIS uses a penumbral coded aperture and has been designed to record images from low yield (10{sup 9}-10{sup 10} neutrons) implosions such as those using deuterium as the fuel. This camera was tested at OMEGA in 2009 on a rugby hohlraum energetics experiment where it recorded an image at a yield of 1.4 Multiplication-Sign 10{sup 10}. The resolution of this image was 54 {mu}m and the camera was located only 4 meters from target chamber centre. We recently improved the instrument by adding a cooled CCD camera. The sensitivity of the new camera has been fully characterized using a linear accelerator and a {sup 60}Co {gamma}-ray source. The calibration showed that the signal-to-noise ratio could be improved by using raw binning detection.

  3. Carbon nanotube quantum dots as highly sensitive THz spectrometers

    Science.gov (United States)

    Rinzan, Mohamed; Jenkins, Greg; Drew, Dennis; Shafranjuk, Serhii; Barbara, Paola

    2012-02-01

    We show that carbon nanotube quantum dots (CNT-Dots) coupled to antennas are extremely sensitive, broad-band, terahertz quantum detectors. Their response is due to photon-assisted single-electron tunneling (PASET)[1], but cannot be fully understood with orthodox PASET models[2]. We consider intra-dot excitations and non-equilibrium cooling to explain the anomalous response. REFERENCES: [1] Y. Kawano, S. Toyokawa, T. Uchida and K. Ishibashi, THz photon assisted tunneling in carbon-nanotube quantum dots, Journal of Applied Physics 103, 034307 (2008). [2] P. K. Tien and J. P. Gordon, Multiphoton Process Observed in the Interaction of Microwave Fields with the Tunneling between Superconductor Films, Phys. Rev. 129, 647 (1963).

  4. High-sensitivity observations of solar flare decimeter radiation

    CERN Document Server

    Benz, Arnold O; Monstein, C; Benz, Arnold O.; Messmer, Peter; Monstein, Christian

    2000-01-01

    A new acousto-optic radio spectrometer has observed the 1 - 2 GHz radio emission of solar flares with unprecedented sensitivity. The number of detected decimeter type III bursts is greatly enhanced compared to observations by conventional spectrometers observing only one frequency at the time. The observations indicate a large number of electron beams propagating in dense plasmas. For the first time, we report weak, reversed drifting type III bursts at frequencies above simultaneous narrowband decimeter spikes. The type III bursts are reliable signatures of electron beams propagating downward in the corona, apparently away from the source of the spikes. The observations contradict the most popular spike model that places the spike sources at the footpoints of loops. Conspicuous also was an apparent bidirectional type U burst forming a fish-like pattern. It occurs simultaneously with an intense U-burst at 600-370 MHz observed in Tremsdorf. We suggest that it intermodulated with strong terrestrial interference ...

  5. Highly sensitive biosensors based on water-soluble conjugated polymers

    Institute of Scientific and Technical Information of China (English)

    XU Hui; WU Haiping; FAN Chunhai; LI Wenxin; ZHANG Zhizhou; HE Lin

    2004-01-01

    Conjugated, conductive polymers are a kind of important organic macromolecules, which has found applications in a variety of areas. The application of conjugated polymers in developing fluorescent biosensors represents the merge of polymer sciences and biological sciences. Conjugated polymers are very good light harvesters as well as fluorescent polymers, and they are also "molecular wires". Through elaborate designs, these important features, i.e. efficient light harvesting and electron/energy transfer, can be used as signal amplification in fluorescent biosensors. This might significantly improve the sensitivity of conjugated polymer-based biosensors. In this article, we reviewed the application of conjugated polymers, via either electron transfer or energy transfer, to detections of gene targets, antibodies or enzymes. We also reviewed recent efforts in conjugated polymer-based solid-state sensor designs as well as chip-based multiple target detection. Possible directions in this conjugated polymer-based biosensor area are also discussed.

  6. Highly sensitive urea sensing with ion-irradiated polymer foils

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Dietmar, E-mail: fink@daad-alumni.de [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 250 68 Rez (Czech Republic); Munoz Hernandez, Gerardo [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Division de Ciencias Naturales e Ingenieria, Universidad Autonoma Metropolitana-Cuajimalpa, Pedro Antonio de los Santos 84, Col. Sn. Miguel Chapultepec, C.P. 11850, Mexico, D.F. (Mexico); Alfonta, Lital, E-mail: alfontal@bgu.ac.il [Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel)

    2012-02-15

    Recently we prepared urea-sensors by attaching urease to the inner walls of etched ion tracks within thin polymer foil. Here, alternative track-based sensor configurations are examined where the enzyme remained in solution. The conductivities of systems consisting of two parallel irradiated polymer foils and confining different urea/urease mixtures in between were examined. The correlations between conductivity and urea concentration differed strongly for foils with unetched and etched tracks, which points at different sensing mechanisms - tentatively attributed to the adsorption of enzymatic reaction products on the latent track entrances and to the enhanced conductivity of reaction product-filled etched tracks, respectively. All examined systems enable in principle, urea sensing. They point at the possibility of sensor cascade construction for more sensitive or selective sensor systems.

  7. A rapid and sensitive method for the determination of hypusine in proteins and its distribution and developmental changes.

    Science.gov (United States)

    Sano, A; Miyake, M; Kakimoto, Y

    1984-07-30

    A simple and sensitive method for determining hypusine in proteins was developed. A greater part of amino acids in the acid hydrolysate of proteins was separated from hypusine by treatment with an ion-exchange resin. The sample containing partially purified hypusine was then analyzed by high-performance liquid chromatography using the post-column derivatization method with o-phthalaldehyde. The recovery rate of hypusine through the overall procedure was more than 95%. Using this method, the distribution and developmental changes of hypusine in proteins were determined. The amino acid was found in proteins of all examined organs of rat. Its concentration was 5-40 nmol/g protein. The subcellular distribution in rat liver was also determined. About 60% of total amount of hypusine was present in the proteins of cytoplasmic and microsomal fractions and its relative concentration was high in the proteins of microsome and lysosome and low in mitochondria. In developing rat, the concentration of hypusine in the brain proteins was relatively high during the first 2 or 3 weeks of postnatal life and then decreased until adulthood. Its concentration in the liver proteins was highest at birth and then decreased continuously to the adult level.

  8. [Sensitive determination of Bi3+ by spectrofluorimetry based on graphene oxide-methylene blue system].

    Science.gov (United States)

    Zhai, Qiu-ge; Guo, Peng; Zhou, Lin; Liu, Yan-ming

    2014-08-01

    Graphene oxide was prepared by the modified Hummers method and characterized by field emission scanning electron microscopy. The interaction of graphene with methylene blue was studied by UV absorption, the intensity of two main absorption peaks of methylene blue decreased significantly after the fluorescence was quenched, and the energy transfer didn't occur because the overlap of the absorption spectrum of GO and the emission spectrum of MB is too small. Therefore, the fluorescence quenching of MB and GO was static. When adding a certain amount of Bi3+ in the graphene-methylene blue system, Bi3+ replaces the methylene blue from the graphene-methylene blue complexes because Bi3+ has the smaller volume and is more positively charged. The methylene blue therefore dissociates from the GO-MB complexes, resulting in the recovery of fluorescence of the system. Furthermore, the fluorescence of the system increases with the increase in the amount of Bi3+ due to the enhanced amount of MB in the system. A novel spectrofluorimetric method was therefore developed for the sensitive determination of Bi3+. Some parameters including the concentration of methylene blue, the amount of graphene oxide, the amount of nitric acid and the sequence of reagent adding were optimized to obtain higher sensitivity. The fluorescence of the system was detected at an emission wavelength of 667 nm with excitation at 690 nm. Under the optimized conditions, the concentration of Bi3+ showed good linear relationships with the fluorescence intensity in the range of 0.5-100 micromol x L(-1), with correlation coefficients of r = 0.9955. The limits of detection for Bi3+ was 1.0 x 10(-8) mol x L(-1) (S/N=3). The selectivity of the proposed method was evaluated and the results showed that 1000-fold K+, Ca+, Na+, Mg2+, Cu2+; 100-fold Fe3+, Be2+, SiO2- Al3+, Ni2+, Sb3+, NO3-, Cl-, F-, and 20-fold Pb2+, Hg2+, Cd2+ had negligible interference with the determination of Bi3+. The method has advantages of

  9. Sensitive Adsorptive Voltammetric Method for Determination of Bisphenol A by Gold Nanoparticle/Polyvinylpyrrolidone-Modified Pencil Graphite Electrode

    Directory of Open Access Journals (Sweden)

    Yesim Tugce Yaman

    2016-05-01

    Full Text Available A novel electrochemical sensor gold nanoparticle (AuNP/polyvinylpyrrolidone (PVP modified pencil graphite electrode (PGE was developed for the ultrasensitive determination of Bisphenol A (BPA. The gold nanoparticles were electrodeposited by constant potential electrolysis and PVP was attached by passive adsorption onto the electrode surface. The electrode surfaces were characterized by electrochemical impedance spectroscopy (EIS and scanning electron microscopy (SEM. The parameters that affected the experimental conditions were researched and optimized. The AuNP/PVP/PGE sensor provided high sensitivity and selectivity for BPA recognition by using square wave adsorptive stripping voltammetry (SWAdSV. Under optimized conditions, the detection limit was found to be 1.0 nM. This new sensor system offered the advantages of simple fabrication which aided the expeditious replication, low cost, fast response, high sensitivity and low background current for BPA. This new sensor system was successfully tested for the detection of the amount of BPA in bottled drinking water with high reliability.

  10. A Sensitive Competitive ELISA for Determination of Biotin in Transformed Yeast Culture Media

    Institute of Scientific and Technical Information of China (English)

    YANGHong

    2003-01-01

    Aim To develop a sensitive competitive ELISA for the determination of biotin in transformed yeast culture media.Methods The ELISA plate was firstly coated with Mycoplasma hyopneumoniae, and then successively incubated with rabbit ami-Mycoplasma hyopneumoniae serum and goat anti-rabbit IgG-biotin to form the solid biotin, which competed with the biotin in the solution (standard or sample) for the limited streptavidin-horse radish peroxidase conjugate. The standard calibration curve for biotin analysis was constructed in the range of 50-2000ng·L-1. Results The detection limit for biotin was found to be 83 ng·L-1 , which waa about 1000 times lower than the lowest determination concenlration in the reported ELISA for biotin analysis. The relative standard deviations for the spiked samples at biotin concerarations of 200 ng·L-1, 500 ng·L-1 , and 1000 ng·L-1 were 24.87%, 6.15%, and 7.86%, respectively, with the average recovery of 101.13%. The wild yeast and its sixty-three transformed yeast culture media were applied to the developed ELISA for the determination of biotin. It was found that the biotin concentrations in more than 85 % of the tested samples were enhanced with different increase factors after transformation. Conclusion Utilization of Mycoplasma hyopnetunoniae as the coating protein improves the precision and accmacy oftbe ELISA assay, which might be used for the biotin assay in other media.

  11. Determination of ranitidine, nizatidine, and cimetidine by a sensitive fluorescent probe.

    Science.gov (United States)

    Chang, Yin-Xia; Qiu, Yue-Qin; Du, Li-Ming; Li, Chang-Feng; Guo, Min

    2011-10-21

    A validated, simple, and sensitive fluorescence quenching method for the determination of ranitidine, nizatidine, and cimetidine in tablets and biological fluids is presented. This is the first single fluorescence method reported for the analysis of all three H(2) antagonists. The competitive reaction between the investigated drug and the palmatine probe for the occupancy of the cucurbit[7]uril (CB[7]) cavity was studied using spectrofluorometry. CB[7] was found to react with the probe to form a stable complex. The fluorescence intensity of the complex was also enhanced greatly. However, the addition of the drug dramatically quenched the fluorescence intensity of the complex. Accordingly, a new fluorescence quenching method for the determination of the studied drugs was established. The different experimental parameters affecting the fluorescence quenching intensity were studied carefully. At optimum reaction conditions, the rectilinear calibration graphs between the fluorescence quenching values (ΔF) and the medicament concentration were obtained in the concentration range of 0.04-1.9 μg mL(-1) for the investigated drugs. The limits of detection ranged from 0.013 to 0.030 μg mL(-1) at 495 nm using an excitation wavelength of 343 nm. The proposed method can be used for the determination of the three H(2) antagonists in raw materials, dosage forms and biological fluids.

  12. Determination of the biotin content of select foods using accurate and sensitive HPLC/avidin binding.

    Science.gov (United States)

    Staggs, C G; Sealey, W M; McCabe, B J; Teague, A M; Mock, D M

    2004-12-01

    Assessing dietary biotin content, biotin bioavailability, and resulting biotin status are crucial in determining whether biotin deficiency is teratogenic in humans. Accuracy in estimating dietary biotin is limited both by data gaps in food composition tables and by inaccuracies in published data. The present study applied sensitive and specific analytical techniques to determine values for biotin content in a select group of foods. Total biotin content of 87 foods was determined using acid hydrolysis and the HPLC/avidin-binding assay. These values are consistent with published values in that meat, fish, poultry, egg, dairy, and some vegetables are relatively rich sources of biotin. However, these biotin values disagreed substantially with published values for many foods. Assay values varied between 247 times greater than published values for a given food to as much as 36% less than the published biotin value. Among 51 foods assayed for which published values were available, only seven agreed within analytical variability (720%). We conclude that published values for biotin content of foods are likely to be inaccurate.

  13. A novel polymer inclusion membranes based optode for sensitive determination of Al3+ ions

    Science.gov (United States)

    Suah, Faiz Bukhari Mohd; Ahmad, Musa; Heng, Lee Yook

    2015-06-01

    A novel approach for the determination of Al3+ from aqueous samples was developed using an optode membrane produced by physical inclusion of Al3+ selective reagent, which is morin into a plasticized poly(vinyl chloride). The inclusion of Triton X-100 was found to be valuable and useful for enhancing the sorption of Al3+ ions from liquid phase into the membrane phase, thus increasing the intensity of optode's absorption. The optode showed a linear increase in the absorbance at λmax = 425 nm over the concentration range of 1.85 × 10-6-1.1 × 10-4 mol L-1 (0.05-3 μg mL-1) of Al3+ ions in aqueous solution after 5 min. The limit of detection was determined to be 1.04 × 10-6 mol L-1 (0.028 μg mL-1). The optode developed in the present work was easily prepared and found to be stable, has good mechanical strength, sensitive and reusable. In addition, the optode was tested for Al3+ determination in lake water, river water and pharmaceutical samples, which the result was satisfactory.

  14. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lu Zenghai; Kasaragod, Deepa K; Matcher, Stephen J, E-mail: z.lu@sheffield.ac.uk, E-mail: s.j.matcher@sheffield.ac.uk [Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield, North Campus, Broad Lane, Sheffield, S3 7HQ (United Kingdom)

    2011-02-21

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincare sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP.

  15. Diagnostic sensitivity of ultrasound, radiography and computed tomography for gender determination in four species of lizards.

    Science.gov (United States)

    Di Ianni, Francesco; Volta, Antonella; Pelizzone, Igor; Manfredi, Sabrina; Gnudi, Giacomo; Parmigiani, Enrico

    2015-01-01

    Gender determination is frequently requested by reptile breeders, especially for species with poor or absent sexual dimorphism. The aims of the current study were to describe techniques and diagnostic sensitivities of ultrasound, radiography, and computed tomography for gender determination (identification of hemipenes) in four species of lizards. Nineteen lizards of known sex, belonging to four different species (Pogona vitticeps, Uromastyx aegyptia, Tiliqua scincoides, Gerrhosaurus major) were prospectively enrolled. With informed owner consent, ultrasound, noncontrast CT, contrast radiography, and contrast CT (with contrast medium administered into the cloaca) were performed in conscious animals. Imaging studies were reviewed by three different operators, each unaware of the gender of the animals and of the results of the other techniques. The lizard was classified as a male when hemipenes were identified. Nineteen lizards were included in the study, 10 females and nine males. The hemipenes were seen on ultrasound in only two male lizards, and appeared as oval hypoechoic structures. Radiographically, hemipenes filled with contrast medium appeared as spindle-shaped opacities. Noncontrast CT identified hemipenes in only two lizards, and these appeared as spindle-shaped kinked structures with hyperattenuating content consistent with smegma. Hemipenes were correctly identified in all nine males using contrast CT (accuracy of 100%). Accuracy of contrast radiography was excellent (94.7%). Accuracy of ultrasound and of noncontrast CT was poor (64.3% and 63.1%, respectively). Findings from the current study supported the use of contrast CT or contrast radiography for gender determination in lizards.

  16. The glucocorticoid receptor 1A3 promoter correlates with high sensitivity to glucocorticoid-induced apoptosis in human lymphocytes.

    Science.gov (United States)

    Liddicoat, Douglas R; Kyparissoudis, Konstantinos; Berzins, Stuart P; Cole, Timothy J; Godfrey, Dale I

    2014-11-01

    Glucocorticoids (GCs) are powerful inhibitors of inflammation and immunity. Although glucocorticoid-induced cell death (GICD) is an important part of GCs actions, the cell types and molecular mechanisms involved are not well understood. Untranslated exon 1A3 of the human glucocorticoid receptor (GR) gene is a major determinant of GICD in GICD-sensitive human cancer cell lines, operating to dynamically upregulate GR levels in response to GCs. We measured the GICD sensitivity of freshly isolated peripheral blood mononuclear cells and thymocytes to dexamethasone in vitro, relating this to GR exon 1A3 expression. A clear GICD sensitivity hierarchy was detected: B cells>thymocytes/natural killer (NK) cells>peripheral T cells. Within thymocyte populations, GICD sensitivity decreased with maturation. Interestingly, NK cell subsets were differentially sensitive to GICD, with CD16(+)CD56(int) (cytotoxic) NK cells being highly resistant to GICD, whereas CD16(-)CD56(hi) (cytokine producing) NK cells were highly sensitive (similar to B cells). B-cell GICD was rescued by co-culture with interleukin-4. Strikingly, although no significant increases in GR protein were observed during 48 h of culture of GICD-sensitive and -resistant cells alike, GR 1A3 expression was increased over pre-culture levels in a manner directly proportional to the GICD sensitivity of each cell type. Accordingly, this is the first evidence that the GR exon 1A3 promoter is differentially regulated during thymic development and maturation of human T cells. Furthermore, human peripheral blood B cells are exquisitely GICD-sensitive in vitro, giving new insight into how GCs may downregulate immunity. Collectively, these data show that GR 1A3 expression is tied with GICD sensitivity in human lymphocytes, underscoring the potential for GR 1A3 expression to be used as a biomarker for sensitivity to GICD.

  17. 脂联素和Hs-CRP在突发性耳聋中的临床意义%Determination of serum adiponectin and high-sensitivity C-reative protein in patients with idiopathic sudden sensorineural hearing loss and its clinical significance

    Institute of Scientific and Technical Information of China (English)

    王霞; 牛善利; 马惠平; 张冬梅; 张敏

    2009-01-01

    Objective To study the role and clinical significance of serum adiponectin and high-sensitivity C-reative protein(Hs-CRP)in idiopathic sudden sensorineural hearing loss by measuring the change of their levels in the patients with idiopathic sudden sensorineural hearing loss.Methods Adiponectin Was determined by ELISA method,Hs-CBP was determined by rate nephelometry immunoassuy.The levels adiponectin and Hs-CRP were determined in the 102 idiopathic sudden sensorineural hearing loss patients who were observed at two different time points:before and after treatment,and thirty-five patients with other neurologic diseases(20with sciatica,16withtrigeminal neuralgia)and thirty healthy people were used as control.Results The levels of Hs-CRP in serum of patients with idiopathic sudden sensorineural hearing loss were markedly higher than those in the two control groups(P<0.01);the levels of Hs-CRP in the idiopathic sudden sensorineural hearing loss group after treatment were significantly less than that before treatment(P<0.01).The levels adiponectin in serum of pailents with idiopathic sudden sensorineural hearing loss were markedly lower than those in the two control groups(P<0.01);the levels of adiponectin in the idiopathic sudden sensorineural hearing loss group after treatment were significantly higher than that before treatment(P<0.01).There was negatively correlation between adiponectin and Hs-CRP in patients with idiopathic sudden sensorineural hearing loss(r=-0.63,P<0.01).Conclusion The levels of serum adiponectin and Hs-CRP have instructive significance in idiopathic sudden sensorineural hearing loss treating and prognosis estimating.%目的 探讨突发性耳聋患者血清脂联素和血清高敏C-反应蛋白(Hs-CRP)的含量变化,及其在突发性耳聋发生过程中的作用和意义.方法 采用酶联免疫(ELISA)法检测血清脂联素含量,采用免疫比浊法对血清Hs-CRP进行测定;检测102例突发性耳聋患者、35

  18. Determination of piroxicam in pharmaceutical formulations and urine samples using europium-sensitized luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Al-Kindy, Salma M.Z. [Department of Chemistry, College of Science, P.O. Box 36, Al-Khod 123, Sultan Qaboos University (Oman)], E-mail: alkindy@squ.edu.om; Suliman, Fakhr Eldin O.; Al-Wishahi, Aisha A.; Al-Lawati, Haidar A.J.; Aoudia, Muhammed [Department of Chemistry, College of Science, P.O. Box 36, Al-Khod 123, Sultan Qaboos University (Oman)

    2007-12-15

    A simple, selective and sensitive luminescence method for the assay of piroxicam (PX) in aqueous solution is developed. The method is based on the luminescence sensitization of europium (Eu{sup 3+}) by formation of ternary complex with PX in the presence of TOPO and Tween-80 as surfactant. The signal for Eu-PX-TOPO is monitored at {lambda}{sub ex}=359 nm and {lambda}{sub em}=615 nm. Optimum conditions for the formation of the complex in sequential injection analysis (SIA) were 0.01 M Tris buffer, pH 7.5, TOPO 5.0x10{sup -5} M, Tween-80 0.15% and 1.5 mM of Eu{sup 3+}, which allows the determination of 100-1000 ppb of PX with limit of detection (LOD) of 29 ppb. The relative standard deviations of the method range between 0.5% and 3.9% indicating excellent reproducibility of the method. The proposed method was successfully applied for the assay of PX in pharmaceutical formulations and in urine samples. Average recoveries of 100.8{+-}1.7% was obtained in tablet, whereas a recovery of 97.5{+-}2.0% was obtained for the total PX (PX+hydoxy-PX) in urine sample.

  19. Registered report: androgen receptor splice variants determine taxane sensitivity in prostate cancer

    Directory of Open Access Journals (Sweden)

    Xiaochuan Shan

    2015-09-01

    Full Text Available The Prostate Cancer Foundation-Movember Foundation Reproducibility Initiative seeks to address growing concerns about reproducibility in scientific research by conducting replications of recent papers in the field of prostate cancer. This Registered Report describes the proposed replication plan of key experiments from “Androgen Receptor Splice Variants Determine Taxane Sensitivity in Prostate Cancer” by Thadani-Mulero and colleagues (2014 published in Cancer Research in 2014. The experiment that will be replicated is reported in Fig. 6A. Thadani-Mulero and colleagues generated xenografts from two prostate cancer cell lines; LuCaP 86.2, which expresses predominantly the ARv567 splice variant of the androgen receptor (AR, and LuCaP 23.1, which expresses the full length AR as well as the ARv7 variant. Treatment of the tumors with the taxane docetaxel showed that the drug inhibited tumor growth of the LuCaP 86.2 cells but not of the LuCaP 23.1 cells, indicating that expression of splice variants of the AR can affect sensitivity to docetaxel. The Prostate Cancer Foundation-Movember Foundation Reproducibility Initiative is a collaboration between the Prostate Cancer Foundation, the Movember Foundation and Science Exchange, and the results of the replications will be published by PeerJ.

  20. High-Precision Direct Mass Determination of Unstable Isotopes

    CERN Multimedia

    2002-01-01

    The extension of systematic high-precision measurements of the nuclear mass to nuclei far from the valley of $\\beta$ stability is of great interest in nuclear physics and astrophysics. The mass, or binding energy, is a fundamental gross property and a key input parameter for nuclear matter calculations. It is also a sensitive probe for collective and single-particle effects in nuclear structure. \\\\ \\\\ For such purposes, nuclear masses need to be known to an accuracy of about 10$^{-7}$ (i.e. $\\Delta$M~$\\leq$~10~keV for A~=~100). To resolve a particular mass from its nuclear isomers and isobars, resolving power of 10$^6$ are often required. To achieve this, the ions delivered by the on-line mass separator ISOLDE are confined in a Penning quadrupole trap. This trap is placed in the very homogeneous and stable magnetic field of a superconducting magnet. Here, the cyclotron frequency and hence the mass are determined. \\\\ \\\\ The first measurements using this new technique have been completed for a long chain of Cs ...

  1. High-sensitivity in situ QCLAS-based ammonia concentration sensor for high-temperature applications

    Science.gov (United States)

    Peng, W. Y.; Sur, R.; Strand, C. L.; Spearrin, R. M.; Jeffries, J. B.; Hanson, R. K.

    2016-07-01

    A novel quantum cascade laser (QCL) absorption sensor is presented for high-sensitivity in situ measurements of ammonia (hbox {NH}_3) in high-temperature environments, using scanned wavelength modulation spectroscopy (WMS) with first-harmonic-normalized second-harmonic detection (scanned WMS-2 f/1 f) to neutralize the effect of non-absorption losses in the harsh environment. The sensor utilized the sQ(9,9) transition of the fundamental symmetric stretch band of hbox {NH}_3 at 10.39 {\\upmu }hbox {m} and was sinusoidally modulated at 10 kHz and scanned across the peak of the absorption feature at 50 Hz, leading to a detection bandwidth of 100 Hz. A novel technique was used to select an optimal WMS modulation depth parameter that reduced the sensor's sensitivity to spectral interference from hbox {H}_2hbox {O} and hbox {CO}_2 without significantly sacrificing signal-to-noise ratio. The sensor performance was validated by measuring known concentrations of hbox {NH}_3 in a flowing gas cell. The sensor was then demonstrated in a laboratory-scale methane-air burner seeded with hbox {NH}_3, achieving a demonstrated detection limit of 2.8 ± 0.26 ppm hbox {NH}_3 by mole at a path length of 179 cm, equivalence ratio of 0.6, pressure of 1 atm, and temperatures of up to 600 K.

  2. Highly sensitive glucose biosensor based on Au-Ni coaxial nanorod array having high aspect ratio.

    Science.gov (United States)

    Hsu, Che-Wei; Wang, Gou-Jen

    2014-06-15

    An effective glucose biosensor requires a sufficient amount of GOx immobilizing on the electrode surface. An electrode of a 3D nanorod array, having a larger surface-to-volume ratio than a 2D nanostructure, can accommodate more GOx molecules to immobilize onto the surface of the nanorods. In this study, a highly sensitive Au-Ni coaxial nanorod array electrode fabricated through the integration of nano electroforming and immersion gold (IG) method for glucose detection was developed. The average diameter of the as-synthesized Ni nanorods and that of the Au-Ni nanorods were estimated to be 150 and 250 nm, respectively; both had a height of 30 μm. The aspect ratio was 120. Compared to that of a flat Au electrode, the effective sensing area was enhanced by 79.8 folds. Actual glucose detections demonstrated that the proposed Au-Ni coaxial nanorod array electrode could operate in a linear range of 27.5 μM-27.5mM with a detection limit of 5.5μM and a very high sensitivity of 769.6 μA mM(-1)cm(-2). Good selectivity of the proposed sensing device was verified by sequential injections of uric acid (UA) and ascorbic acid (AA). Long-term stability was examined through successive detections over a period of 30 days.

  3. Highly Sensitive and Selective Amperometric Sensor for Iodate Based on 9,10-Phenanthrenequinone Derived Graphene

    Institute of Scientific and Technical Information of China (English)

    WANG Hong-juan; CHENG Na-na; YANG Xiao-yang; LI Xiao-meng; ZHU Lian-de

    2013-01-01

    We reported on a new amperometric sensor for the sensitive and selective determination of iodate in table salt.The iodate sensor was constructed by the integration of a novel nanocomposite which was made from 9,10-phenanthrenequinone(PQ) and graphene(GP) with a glassy carbon electrode(GCE).The synthesized graphene and the nanocomposite were well characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),Fourier transform infrared(FTIR) spectroscopy and Raman spectroscopy.We fully studied the electrochemical behavior and kinetic characteristics of the PQ/GP nanocomposite at GCE.The PQ/GP electrode shows a good electrochemical catalytic activity towards the reduction of iodate,which makes itself a sensitive and selective electrochemical sensor for iodate.The iodate sensor displays a high sensitivity(1.04 μA·μmol.L-1),a low detection limit(1.0× 10-8mol/L),a rapid response(less than 2 s),and a broad linear range(from 5.0× 10-8 mol/L to 6.0× 10-3 mol/L).In addition,the sensor is interference free.The practical application of the proposed sensor was tested by the detection of iodate in table salt.

  4. Nitrogen detected TROSY at high field yields high resolution and sensitivity for protein NMR

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, Koh [National Institute for Advanced Industrial Science and Technology, Molecular Profiling Research Center for Drug Discovery (Japan); Arthanari, Haribabu [Harvard Medical School, Department of Biochemistry and Molecular Pharmacology (United States); Shimada, Ichio, E-mail: shimada@iw-nmr.f.u-tokyo.ac.jp [National Institute for Advanced Industrial Science and Technology, Molecular Profiling Research Center for Drug Discovery (Japan); Wagner, Gerhard, E-mail: gerhard-wagner@hms.harvard.edu [Harvard Medical School, Department of Biochemistry and Molecular Pharmacology (United States)

    2015-12-15

    Detection of {sup 15}N in multidimensional NMR experiments of proteins has sparsely been utilized because of the low gyromagnetic ratio (γ) of nitrogen and the presumed low sensitivity of such experiments. Here we show that selecting the TROSY components of proton-attached {sup 15}N nuclei (TROSY {sup 15}N{sub H}) yields high quality spectra in high field magnets (>600 MHz) by taking advantage of the slow {sup 15}N transverse relaxation and compensating for the inherently low {sup 15}N sensitivity. The {sup 15}N TROSY transverse relaxation rates increase modestly with molecular weight but the TROSY gain in peak heights depends strongly on the magnetic field strength. Theoretical simulations predict that the narrowest line width for the TROSY {sup 15}N{sub H} component can be obtained at 900 MHz, but sensitivity reaches its maximum around 1.2 GHz. Based on these considerations, a {sup 15}N-detected 2D {sup 1}H–{sup 15}N TROSY-HSQC ({sup 15}N-detected TROSY-HSQC) experiment was developed and high-quality 2D spectra were recorded at 800 MHz in 2 h for 1 mM maltose-binding protein at 278 K (τ{sub c} ∼ 40 ns). Unlike for {sup 1}H detected TROSY, deuteration is not mandatory to benefit {sup 15}N detected TROSY due to reduced dipolar broadening, which facilitates studies of proteins that cannot be deuterated, especially in cases where production requires eukaryotic expression systems. The option of recording {sup 15}N TROSY of proteins expressed in H{sub 2}O media also alleviates the problem of incomplete amide proton back exchange, which often hampers the detection of amide groups in the core of large molecular weight proteins that are expressed in D{sub 2}O culture media and cannot be refolded for amide back exchange. These results illustrate the potential of {sup 15}N{sub H}-detected TROSY experiments as a means to exploit the high resolution offered by high field magnets near and above 1 GHz.

  5. Determination of the actuator sensitivity of electromechanical polypropylene films by atomic force microscopy

    Science.gov (United States)

    Peltonen, Jouko; Paajanen, Mika; Lekkala, Jukka

    2000-10-01

    The actuator functionality of electromechanical polypropylene films was studied using atomic force microscopy. The film carries a permanent electric charge and includes microbubbles as a result of two-dimensional stretching of the film. The thickness change of various film structures covered with electrodes was measured as a function of external voltage. The dependence was found to be nonlinear, the thickness change in the range 0.001%-0.1% of the total film thickness and affected by the internal charge density of the film. Applying a capacitor model including an air gap within the polymer layer enabled the determination of the Young's modulus, the interfacial charge density and the actuator sensitivity of the studied structures.

  6. Determination and sensitivity analysis of the seismic velocity of a shallow layer from refraction traveltimes measures

    Directory of Open Access Journals (Sweden)

    S Zein

    2016-03-01

    Full Text Available In this paper, we are interested in determining the seismic velocity of ashallow under-ground layer from refraction traveltimes measures. Wepresent a study case taken from an experimental seismic survey. The studycase is a wide-angle seismic inversion using experimental traveltimesmeasures and based on ray tracing technique and genetic algorithms. Thehypothesis on the velocity distribution, coming from the seismicexperiment, makes the computation of some seismic rays expensive intime. We propose to reduce the computations time by introducing aformulation of the inverse problem that avoids such costly rays, hence theinversion becomes feasible.Also we present a sensitivity analysis based on a singular valuedecomposition of the jacobian of the traveltimes with respect to velocity.We give the relationship between the traveltimes measure errors and thevelocity estimation error. We discuss the advantages of this method overthe classical one based on the resolution matrix.

  7. Fast and Sensitive Method for Determination of Domoic Acid in Mussel Tissue

    Directory of Open Access Journals (Sweden)

    Elena Barbaro

    2016-01-01

    Full Text Available Domoic acid (DA, a neurotoxic amino acid produced by diatoms, is the main cause of amnesic shellfish poisoning (ASP. In this work, we propose a very simple and fast analytical method to determine DA in mussel tissue. The method consists of two consecutive extractions and requires no purification steps, due to a reduction of the extraction of the interfering species and the application of very sensitive and selective HILIC-MS/MS method. The procedural method was validated through the estimation of trueness, extract yield, precision, detection, and quantification limits of analytical method. The sample preparation was also evaluated through qualitative and quantitative evaluations of the matrix effect. These evaluations were conducted both on the DA-free matrix spiked with known DA concentration and on the reference certified material (RCM. We developed a very selective LC-MS/MS method with a very low value of method detection limit (9 ng g−1 without cleanup steps.

  8. Determination of serum resistin and high-sensitivity C-reactive protein in patients with idiopathic sudden sensorineural hearing loss and their clinical significance%抵抗素和高敏C-反应蛋白在突发性耳聋中的临床意义

    Institute of Scientific and Technical Information of China (English)

    牛善利; 马惠平; 张冬梅; 黄友敏

    2008-01-01

    目的 探讨突发性耳聋患者血清抵抗素和高敏C-反应蛋白(hs-CRP)的含量变化,及其在突发性耳聋发生过程中的作用和意义.方法 检测102例突发性耳聋组、35例其他疾病对照组和30例健康对照组的血清抵抗素和hs-CRP含量,并比较治疗前后血清抵抗素和hs-CRP含量的变化.结果 突发性耳聋组患者治疗前血清抵抗素和hs-CRP含量较其他疾病对照组和健康对照组显著升高(P<0.01);治疗后突发性耳聋组患者抵抗素和hs-CRP含量明显降低.突发性耳聋患者血清抵抗素和hs-CRP含量呈正相关(r=0.65,P<0.01).结论 血清抵抗素和hs-CRP含量的变化与突发性耳聋病情严重程度密切相关.%Objective To study the role of serum resistin and high-sensitivity C-reactive protein (hs-CRP) in idiopathic sudden sensorineural hearing loss. Methods The levels resistin and hs-CRP were determined in the 102 idiopathic sudden sensorineural hearing loss patients who were observed at two differ-ent time points: before and after treatment, and 35 patients with other neurologic diseases and 30 healthy people were used as control. Results The levels resistin and hs-CRP in serum of patients with idiopathic sudden sensorineural hearing loss were markedly higher than those in the controls (P< 0.01). The levels of resistin and ha-CRP in the patients with idiopathic sudden sensorineural hearing loss after treatment were significantly less than those before treatment. There was a correlation between serum resistin and hs-CRP in patients with idiopathic sudden senserineural hearing loss (r=0.65, P<0.01). Conclusion The levels of serum resistin and hs-CRP have instructive significance in idiopathic sudden sensorineural hearing loss treating and prognosis estimating.

  9. Sub-picometer multi-wavelength detector based on highly sensitive nanomechanical resonator

    Science.gov (United States)

    Maeda, Etsuo; Kometani, Reo

    2017-07-01

    The wavelength division multiplexing (WDM) method for near infrared (NIR) optical fiber (1530-1565 nm) is the system that is wildly used for intercontinental communication. WDM achieves high-speed and large-capacity communication, but costs a lot because the high-resolution (˜10 pm) wavelength locker for wavelength stabilization only corresponds to a single wavelength. In this report, we propose a highly sensitive sub-picometer multi-wavelength detector that substitutes a typical single-wavelength detector for WDM. Our wavelength detector consists of a narrow band (FWHM 20 000) nanomechanical resonator. The photonic absorber confines and transforms the illuminated NIR light wave into thermal stress, and then, the thermal stress in the nanomechanical resonator will appear as the eigenfrequency shift of the nanomechanical resonator. Through experimental works with an NIR laser and optical Doppler vibration meter, the sensitivity of our wavelength detector was determined to be 0.196 pm in the 10-nm-range of the NIR region. Our sub-picometer multi-wavelength detector will achieve a fast, wide-band, and cost-effective optical communication system.

  10. Highly sensitive index of sympathetic activity based on time-frequency spectral analysis of electrodermal activity.

    Science.gov (United States)

    Posada-Quintero, Hugo F; Florian, John P; Orjuela-Cañón, Álvaro D; Chon, Ki H

    2016-09-01

    Time-domain indices of electrodermal activity (EDA) have been used as a marker of sympathetic tone. However, they often show high variation between subjects and low consistency, which has precluded their general use as a marker of sympathetic tone. To examine whether power spectral density analysis of EDA can provide more consistent results, we recently performed a variety of sympathetic tone-evoking experiments (43). We found significant increase in the spectral power in the frequency range of 0.045 to 0.25 Hz when sympathetic tone-evoking stimuli were induced. The sympathetic tone assessed by the power spectral density of EDA was found to have lower variation and more sensitivity for certain, but not all, stimuli compared with the time-domain analysis of EDA. We surmise that this lack of sensitivity in certain sympathetic tone-inducing conditions with time-invariant spectral analysis of EDA may lie in its inability to characterize time-varying dynamics of the sympathetic tone. To overcome the disadvantages of time-domain and time-invariant power spectral indices of EDA, we developed a highly sensitive index of sympathetic tone, based on time-frequency analysis of EDA signals. Its efficacy was tested using experiments designed to elicit sympathetic dynamics. Twelve subjects underwent four tests known to elicit sympathetic tone arousal: cold pressor, tilt table, stand test, and the Stroop task. We hypothesize that a more sensitive measure of sympathetic control can be developed using time-varying spectral analysis. Variable frequency complex demodulation, a recently developed technique for time-frequency analysis, was used to obtain spectral amplitudes associated with EDA. We found that the time-varying spectral frequency band 0.08-0.24 Hz was most responsive to stimulation. Spectral power for frequencies higher than 0.24 Hz were determined to be not related to the sympathetic dynamics because they comprised less than 5% of the total power. The mean value of time

  11. A highly sensitive underwater video system for use in turbid aquaculture ponds

    Science.gov (United States)

    Hung, Chin-Chang; Tsao, Shih-Chieh; Huang, Kuo-Hao; Jang, Jia-Pu; Chang, Hsu-Kuang; Dobbs, Fred C.

    2016-01-01

    The turbid, low-light waters characteristic of aquaculture ponds have made it difficult or impossible for previous video cameras to provide clear imagery of the ponds’ benthic habitat. We developed a highly sensitive, underwater video system (UVS) for this particular application and tested it in shrimp ponds having turbidities typical of those in southern Taiwan. The system’s high-quality video stream and images, together with its camera capacity (up to nine cameras), permit in situ observations of shrimp feeding behavior, shrimp size and internal anatomy, and organic matter residues on pond sediments. The UVS can operate continuously and be focused remotely, a convenience to shrimp farmers. The observations possible with the UVS provide aquaculturists with information critical to provision of feed with minimal waste; determining whether the accumulation of organic-matter residues dictates exchange of pond water; and management decisions concerning shrimp health. PMID:27554201

  12. A highly sensitive underwater video system for use in turbid aquaculture ponds

    Science.gov (United States)

    Hung, Chin-Chang; Tsao, Shih-Chieh; Huang, Kuo-Hao; Jang, Jia-Pu; Chang, Hsu-Kuang; Dobbs, Fred C.

    2016-08-01

    The turbid, low-light waters characteristic of aquaculture ponds have made it difficult or impossible for previous video cameras to provide clear imagery of the ponds’ benthic habitat. We developed a highly sensitive, underwater video system (UVS) for this particular application and tested it in shrimp ponds having turbidities typical of those in southern Taiwan. The system’s high-quality video stream and images, together with its camera capacity (up to nine cameras), permit in situ observations of shrimp feeding behavior, shrimp size and internal anatomy, and organic matter residues on pond sediments. The UVS can operate continuously and be focused remotely, a convenience to shrimp farmers. The observations possible with the UVS provide aquaculturists with information critical to provision of feed with minimal waste; determining whether the accumulation of organic-matter residues dictates exchange of pond water; and management decisions concerning shrimp health.

  13. Properties of recombinant human N1-acetylpolyamine oxidase (hPAO): potential role in determining drug sensitivity.

    Science.gov (United States)

    Wang, Yanlin; Hacker, Amy; Murray-Stewart, Tracy; Frydman, Benjamin; Valasinas, Aldonia; Fraser, Alison V; Woster, Patrick M; Casero, Robert A

    2005-07-01

    The recent cloning of the mammalian gene coding for N(1)-acetylpolyamine oxidase (PAO) provides the opportunity to directly examine the role of human PAO (hPAO) in polyamine homeostasis as well as its potential role in determining cellular response to antitumor polyamine analogues. To facilitate the study of this enzyme, the production, purification, and characterization of the recombinant hPAO is reported. hPAO oxidizes N(1)-acetylspermidine (K(m)=2.1 microM, K(cat)=15.0 s(-1)) and has very high affinity for N(1)-acetylspermine (K(m)=0.85 microM, K(cat)=31.7 s(-1)). The recombinant hPAO does not efficiently oxidize spermine, thereby demonstrating a significant difference in substrate specificity from the previously described human spermine oxidase PAOh1/SMO. Importantly, hPAO demonstrates the ability to oxidize a subset of antitumor polyamine analogues, suggesting that this oxidase activity could have a significant effect on determining tumor sensitivity to these or similar agents. Transfection of A549 human lung cancer cells with an hPAO-expressing plasmid leads to a profound decrease in sensitivity to those analogues which act as substrates, confirming its potential to alter drug response. One similarity that hPAO shares with human PAOh1/SMO, is that certain oligoamine analogues are potent inhibitors of its oxidase activity. The results of these studies demonstrate how changes in polyamine catabolism may affect drug response.

  14. Molecularly imprinted solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of safranine T in wolfberry.

    Science.gov (United States)

    Su, Zihao; Zhai, Haiyun; Chen, Zuanguang; Zhou, Qing; Li, Jiangmei; Liu, Zhenping

    2014-02-01

    A method was developed to sensitively determine safranine T in wolfberry by molecularly imprinted solid-phase extraction (MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC-LIF). The MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using safranine T, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions and the morphologies of inner polymers were characterized by scanning electron microscopy (SEM). The mean recoveries of safranine T in wolfberry ranged from 91.2 % to 92.9 % and the intraday and interday relative standard deviation (RSD) values all ranged from 3.4 % to 4.2 %. Good linearity was obtained over 0.001-1.0 μg mL(-1) (r = 0.9999) with a detection limit (S/N = 3) of 0.4 ng g(-1). Under the selected conditions, enrichment factors of over 90-fold were obtained and the extraction on the monolithic column effectively cleaned up the wolfberry matrix. The results demonstrated that the proposed MISPE-HPLC-LIF method could be applied to sensitively determine safranine T in wolfberry.

  15. A rapid method for determining salinomycin and monensin sensitivity in Eimeria tenella.

    Science.gov (United States)

    Jenkins, M C; O'Brien, C N; Fuller, L; Mathis, G F; Fetterer, R

    2014-12-15

    Standard methods of determining the ionophore sensitivity of Eimeria rely on infecting chickens with an isolate or a mixture of Eimeria spp. oocysts in the presence of different anti-coccidial drugs. The purpose of this study was to develop a rapid in vitro method for assessing salinomycin and monensin sensitivity in Eimeria tenella. Cultures of MDBK cells were grown to 85% confluency, and then inoculated with excysted E. tenella laboratory strain (APU-1) sporozoites in the presence of different concentrations of salinomycin or monensin. At various timepoints, the monolayers were fixed for counting intraceullar sporozoites, or were subjected to DNA extraction, followed by molecular analysis using quantitative (qPCR) or semi-quantitative PCR (sqPCR). Preliminary experiments showed that 24h was the optimum time for harvesting the E. tenella-infected cell cultures. The average number of E. tenella sporozoites relative to untreated controls displayed a linear decrease between 0.3 and 33.0 μg/ml salinomycin and between 0.3 and 3.3 μg/ml monensin. A similar pattern was observed in the relative amount of E. tenella DNA as measured by sqPCR. A linear decrease in the relative amount of E. tenella DNA was observed over the entire range of salinomycin and monensin concentrations as measured by qPCR possibly reflecting the greater sensitivity of this assay. Comparison of sporozoite counting, sqPCR, and qPCR signals using a criterion of 50% inhibition in sporozoite numbers or level of PCR amplification product showed good agreement between the three assays. E. tenella field isolates (FS-1 and FS-2) displaying resistance to salinomycin and monensin were evaluated in the in vitro assay using qPCR and sqPCR. Compared to E. tenella APU-1, the E. tenella FS-1 and FS-2 isolates showed higher levels of E. tenella DNA at 24h by both qPCR and sqPCR. This in vitro assay represents a significant advance in developing rapid, cost-effective methods for assessing ionophore sensitivity in E

  16. Achieving tunable sensitivity in composite high-energy density materials

    Science.gov (United States)

    Kuklja, Maija M.; Tsyshevsky, Roman V.; Rashkeev, Sergey

    2017-01-01

    Laser irradiation provides a unique opportunity for selective, predictive, and controlled initiation of energetic materials. We propose a consistent micro-scale mechanism of photoexcitation at the interface, formed by a molecular energetic material and a metal oxide. A specific PETN-MgO model composite is used to illustrate and explain seemingly puzzling experiments on selective laser initiation of energetic materials, which reported that the presence of metal oxide additives triggered the photoinitiation by an unusually low energy. We suggest that PETN photodecomposition is catalyzed by oxygen vacancies (F0 centers) at the MgO surface. The proposed model suggests ways to tune sensitivity of energetic molecular materials to photoinitiation. Our quantum-chemical calculations suggest that the structural point defects (e.g., oxygen vacancies) strongly interact with the molecular material (e.g., adsorbed energetic molecules) by inducing a charge transfer at the interface and hence play an imperative role in governing both energy absorption and energy release in the system. Our approach and conclusions provide a solid basis for novel design of energetic interfaces with desired properties and offers a new perspective in the field of explosive materials and devices.

  17. High-sensitivity observations of solar flare decimeter radiation

    Science.gov (United States)

    Benz, A. O.; Messmer, P.; Monstein, C.

    2001-01-01

    A new acousto-optic radio spectrometer has observed the 1-2 GHz radio emission of solar flares with unprecedented sensitivity. The number of detected decimeter type III bursts is greatly enhanced compared to observations by conventional spectrometers observing only one frequency at the time. The observations indicate a large number of electron beams propagating in dense plasmas. For the first time, we report weak, reversed drifting type III bursts at frequencies above simultaneous narrowband decimeter spikes. The type III bursts are reliable signatures of electron beams propagating downward in the corona, apparently away from the source of the spikes. The observations contradict the most popular spike model that places the spike sources at the footpoints of loops. Conspicuous also was an apparent bidirectional type U burst forming a fish-like pattern. It occurs simultaneously with an intense U-burst at 600-370 MHz observed in Tremsdorf. We suggest that it intermodulated with strong terrestrial interference(cellular phones) causing a spurious symmetric pattern in the spectrogram at 1.4 GHz. Symmetric features in the 1-2 GHz range, some already reported in the literature, therefore must be considered with utmost caution.

  18. Furazans with Azo Linkages: Stable CHNO Energetic Materials with High Densities, Highly Energetic Performance, and Low Impact and Friction Sensitivities.

    Science.gov (United States)

    Qu, Yanyang; Zeng, Qun; Wang, Jun; Ma, Qing; Li, Hongzhen; Li, Haibo; Yang, Guangcheng

    2016-08-22

    Various highly energetic azofurazan derivatives were synthesized by simple and efficient chemical routes. These nitrogen-rich materials were fully characterized by FTIR spectroscopy, elemental analysis, multinuclear NMR spectroscopy, and high-resolution mass spectrometry. Four of them were further confirmed structurally by single-crystal X-ray diffraction. These compounds exhibit high densities, ranging from 1.62 g cm(-3) up to a remarkably high 2.12 g cm(-3) for nitramine-substituted azofurazan DDAzF (2), which is the highest yet reported for an azofurazan-based CHNO energetic compound and is a consequence of the formation of strong intermolecular hydrogen-bonding networks. From the heats of formation, calculated with Gaussian 09, and the experimentally determined densities, the energetic performances (detonation pressure and velocities) of the materials were ascertained with EXPLO5 v6.02. The results suggest that azofurazan derivatives exhibit excellent detonation properties (detonation pressures of 21.8-46.1 GPa and detonation velocities of 6602-10 114 m s(-1) ) and relatively low impact and friction sensitivities (6.0-80 J and 80-360 N, respectively). In particular, they have low electrostatic spark sensitivities (0.13-1.05 J). These properties, together with their high nitrogen contents, make them potential candidates as mechanically insensitive energetic materials with high-explosive performance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. HIGH SENSITIVE C-REACTIVE PROTEIN IN CEREBROVASCULAR ISCHEMIA

    Directory of Open Access Journals (Sweden)

    Padmalatha

    2016-02-01

    Full Text Available BACKGROUND Cerebrovascular ischemia is recognized as a major health problem, which causes significant morbidity and mortality. The main pathophysiology of ischemic stroke is atherosclerosis of cerebral vessels. Hs-CRP is a sensitive marker of inflammation tissue injury in the arterial wall, which contributes to atherosclerosis. In this study, we aim to investigate the association of hs-CRP in patients with ischemic stroke and to correlate hs-CRP levels with possible risk factors of ischemic stroke and to assess the prognostic value of hs-CRP in ischemic stroke. METHODS In the present case control study after meeting inclusion and exclusion criteria, 50 patients with acute ischemic stroke admitted in the medical ward, King George Hospital, during the period between April 2014 and October 2014 and 40 asymptomatic age and sex matched control subjects were included. RESULTS The mean hs-CRP value in cases is 3.78+5.28mg/dl and in controls is 0.425+0.305mg/dl. Mean hs-CRP value is higher (3.78mg/dl in cases when compared to controls (0.425mg/dl, which is statistically significant. P admitted with severe degree of weakness (0-1/5 power with mean hs-CRP value of 4.28+4.07 without significant improvement in the power at the time of discharge; 8(16%> with mean hs-CRP value of 10.43+7.74 were expired. CONCLUSION Acute ischemic patients had higher mean hs-CRP values when compared to healthy asymptomatic control subjects P0.05. Higher mean hs-CRP values were associated with poor outcome after acute ischemic stroke. P<0.001.

  20. Molecular structure and thermodynamic predictions to create highly sensitive microRNA biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Larkey, Nicholas E.; Brucks, Corinne N.; Lansing, Shan S.; Le, Sophia D.; Smith, Natasha M.; Tran, Victoria; Zhang, Lulu; Burrows, Sean M., E-mail: sean.burrows@oregonstate.edu

    2016-02-25

    Many studies have established microRNAs (miRNAs) as post-transcriptional regulators in a variety of intracellular molecular processes. Abnormal changes in miRNA have been associated with several diseases. However, these changes are sometimes subtle and occur at nanomolar levels or lower. Several biosensing hurdles for in situ cellular/tissue analysis of miRNA limit detection of small amounts of miRNA. Of these limitations the most challenging are selectivity and sensor degradation creating high background signals and false signals. Recently we developed a reporter+probe biosensor for let-7a that showed potential to mitigate false signal from sensor degradation. Here we designed reporter+probe biosensors for miR-26a-2-3p and miR-27a-5p to better understand the effect of thermodynamics and molecular structures of the biosensor constituents on the analytical performance. Signal changes from interactions between Cy3 and Cy5 on the reporters were used to understand structural aspects of the reporter designs. Theoretical thermodynamic values, single stranded conformations, hetero- and homodimerization structures, and equilibrium concentrations of the reporters and probes were used to interpret the experimental observations. Studies of the sensitivity and selectivity revealed 5–9 nM detection limits in the presence and absence of interfering off-analyte miRNAs. These studies will aid in determining how to rationally design reporter+probe biosensors to overcome hurdles associated with highly sensitive miRNA biosensing. - Highlights: • Challenges facing highly sensitive miRNA biosensor designs are addressed. • Thermodynamic and molecular structure design metrics for reporter+probe biosensors are proposed. • The influence of ideal and non-ideal reporter hairpin structures on reporter+probe formation and signal change are discussed. • 5–9 nM limits of detection were observed with no interference from off-analytes.

  1. High Sensitivity Indium Phosphide Based Avalanche Photodiode Focal Plane Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — nLight has demonstrated highly-uniform APD arrays based on the highly sensitive InGaAs/InP material system. These results provide great promise for achieving the...

  2. Polycarbonates: a long-term highly sensitive radon monitor

    CERN Document Server

    Pressyanov, D; Poffijn, A; Meesen, G; Deynse, A V

    2000-01-01

    An approach for long-term (either retrospective or prospective) sup 2 sup 2 sup 2 Rn measurements is proposed that is based on the combination of the high radon absorption ability of some polycarbonates with their alpha track-etch properties. The detection limit is projected to be <10 Bq m sup - sup 3 for an exposure time of 20 yr.

  3. 7 CFR 12.22 - Highly erodible field determination criteria.

    Science.gov (United States)

    2010-01-01

    ... Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria. (a... included in an approved conservation plan for the entire highly erodible field....

  4. A rapid and sensitive alcohol oxidase/catalase conductometric biosensor for alcohol determination.

    Science.gov (United States)

    Hnaien, M; Lagarde, F; Jaffrezic-Renault, N

    2010-04-15

    A new conductometric biosensor has been developed for the determination of short chain primary aliphatic alcohols. The biosensor assembly was prepared through immobilization of alcohol oxidase from Hansenula sp. and bovine liver catalase in a photoreticulated poly(vinyl alcohol) membrane at the surface of interdigitated microelectrodes. The local conductivity increased rapidly after alcohol addition, reaching steady-state within 10 min. The sensitivity was maximal for methanol (0.394+/-0.004 microS microM(-1), n=5) and decreased by increasing the alcohol chain length. The response was linear up to 75 microM for methanol, 70 microM for ethanol and 65 microM for 1-propanol and limits of detection were 0.5 microM, 1 microM and 3 microM, respectively (S/N=3). No significant loss of the enzyme activities was observed after 3 months of storage at 4 degrees C in a 20mM phosphate buffer solution pH 7.2 (two or three measurements per week). After 4 months, 95% of the initial signal still remained. The biosensor response to ethanol was not significantly affected by acetic, lactic, ascorbic, malic, oxalic, citric, tartaric acids or glucose. The bi-enzymatic sensor was successfully applied to the determination of ethanol in different alcoholic beverages.

  5. Ultra-sensitive Flow Injection Analysis (FIA) determination of calcium in ice cores at ppt level.

    Science.gov (United States)

    Traversi, R; Becagli, S; Castellano, E; Maggi, V; Morganti, A; Severi, M; Udisti, R

    2007-07-02

    A Flow Injection Analysis (FIA) spectrofluorimetric method for calcium determination in ice cores was optimised in order to achieve better analytical performances which would make it suitable for reliable calcium measurements at ppt level. The method here optimised is based on the formation of a fluorescent compound between Ca and Quin-2 in buffered environment. A careful evaluation of operative parameters (reagent concentration, buffer composition and concentration, pH), influence of interfering species possibly present in real samples and potential favourable effect of surfactant addition was carried out. The obtained detection limit is around 15 ppt, which is one order of magnitude lower than the most sensitive Flow Analysis method for Ca determination currently available in literature and reproducibility is better than 4% for Ca concentrations of 0.2 ppb. The method was validated through measurements performed in parallel with Ion Chromatography on 200 samples from an alpine ice core (Lys Glacier) revealing an excellent fit between the two chemical series. Calcium stratigraphy in Lys ice core was discussed in terms of seasonal pattern and occurrence of Saharan dust events.

  6. Sensitive Bromatometric Methods for the Determination of Sumatriptan Succinate in Pharmaceutical Formulations

    Directory of Open Access Journals (Sweden)

    K. V. V. Satyanarayana

    2011-01-01

    Full Text Available Two simple and sensitive spectrophotometric methods are described for the determination of sumatriptan succinate (STS in pure and tablets using bromate-bromide as the bromination reagent in acid medium and two dyes as subsidiary reagents. The two methods are based on the bromination of STS by a known excess of in situ generated bromine followed by determination of unreacted bromine by reacting with a fixed amount of methyl orange (Method A or indigo carmine (Method B and measuring the absorbance at 508 or 610 nm. In both methods, the amount of bromine reacted corresponds to the amount of STS. The experimental conditions for the assay have been optimized. In two methods, the absorbance was found to increase linearly with the concentration of STS at the respective wavelengths. Beer’s law was obeyed over the ranges 0.2-1.6 and 2.0-12.0 μg mL-1 for method A and method B respectively and the respective molar absorptivity values were 1.898×105 and 2.71×104 L mol-1 cm-1. The statistical analysis of the methods was validated according to the present ICH guidelines. The proposed methods were applied to the analysis of tablet form of STS and the results tallied well with the label claim.

  7. A new sensitive flow-injection chemiluminescence method for the determination of H(2)-receptor antagonists.

    Science.gov (United States)

    Tang, Yu-Hai; Wang, Nan-Nan; Xiong, Xun-Yu; Xiong, Feng-Mei; Sun, Si-Juan

    2007-01-01

    Based on the chemiluminescence (CL) intensity generated from the potassium ferricyanide [K(3)Fe(CN)(6)]-rhodamine 6G system in sodium hydroxide (NaOH) medium, a new sensitive flow-injection chemiluminescence (FI-CL) method has been developed, validated and applied for the determination of three kinds of H(2)-receptor antagonists: cimetidine (CIMT), ranitidine (RANT) hydrochloride and famotidine (FAMT). Under the optimum conditions, the linear range for the determination was 1.0 x 10(-9)-7.0 x 10(-5) g/ml for CIMT, 1.0 x 10(-9)-5.0 x 10(-5) g/mL for RANT hydrochloride and 5.0 x 10(-9)-7.0 x 10(-5) g/mL for FAMT. During 11 repeated measurements of 1.0 x 10(-6) g/mL sample solutions, the relative standard deviations (RSDs) were all <5%. The detection limit was 8.56 x 10(-10) g/mL for CIMT, 8.69 x 10(-10) g/mL for RANT hydrochloride and 2.35 x 10(-9) g/mL for FAMT (S:N = 3). This method has been successfully implemented for the analysis of H(2)-receptor antagonists in pharmaceuticals.

  8. A rapid and sensitive spectrophotometric method for the determination of benzoyl peroxide in wheat flour samples

    Directory of Open Access Journals (Sweden)

    Kraingkrai Ponhong

    2015-12-01

    Full Text Available A simple, rapid, and sensitive spectrophotometric method for the determination of benzoyl peroxide (BPO in wheat flour samples was developed. The detection principle is based on BPO reacted with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS to obtain a blue-green colored product that was detected at 415 nm by spectrophotometry. The effect of factors influencing the color reaction was investigated. Under the selected conditions, the linear range for quantification of BPO was observed between 0.2–1.0 mg L−1 with r2 = 0.998. The limit of detection (LOD was 0.025 mg L−1. The developed method obtained superior precision (relative standard deviation < 2% using 11 repeatability at 0.2 mg L−1, 0.6 mg L−1, and 0.8 mg L−1. The proposed methodology was successfully applied to determine BPO in wheat flour samples.

  9. A pricing strategy to promote sales of lower fat foods in high school cafeterias: acceptability and sensitivity analysis.

    Science.gov (United States)

    Hannan, Peter; French, Simone A; Story, Mary; Fulkerson, Jayne A

    2002-01-01

    Prices of four low fat foods were reduced about 25% and prices of three high fat foods were increased about 10% to determine the impact on food purchases in a Midwestern suburban high school cafeteria to explore the impact of price on purchases. Low fat foods averaged about 13% of total sales. Sensitivity analysis was used to estimate that low fat foods would probably have averaged about 9% of total sales without the reduced price.

  10. Microstructure-Sensitive Modeling of High Cycle Fatigue (Preprint)

    Science.gov (United States)

    2009-03-01

    history ( carburization and shot peening) and resulting residual stresses are considered in the case of subsurface crack formation at primary inclusions...experimental responses for known mi