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1

A rapid and highly sensitive UPLC-MS/MS method using pre-column derivatization with 2-picolylamine for intravenous and percutaneous pharmacokinetics of valproic acid in rats.  

PubMed

A rapid, highly sensitive and specific ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) for the detection of valproic acid (VPA) in rat plasma following the topical application was developed and validated. This method was carried out with pre-column derivatization using 2-picolylamine (PA) which reacts with the carboxylic acid group of VPA. The derivatization was completed in 10min and the resulting PA-VPA derivative enabled the sensitive detection of VPA in selected reaction monitoring (SRM) mode. Sample preparation was done with simple liquid-liquid extraction and chromatographic separation was achieved within 5min on a C18 column using a gradient elution with the mobile phase of 2mM ammonium formate containing 0.1% formic acid and methanol. The standard curves were linear over the concentration range of 0.07-200?g/mL with a correlation coefficient higher than 0.99. The limit of detection (LOD) and the lower limit of quantification (LLOQ) was 0.03 and 0.07?g/mL, respectively with 100?L of plasma sample. The intra- and inter-day precisions were measured to be below 10.7% and accuracies were within the range of 94.1-115.9%. The validated method was successfully applied to the pharmacokinetics of VPA in the rat following topical and intravenous applications. PMID:24041657

Joo, Kyung-Mi; Choi, Dalwoong; Park, Yang-Hui; Yi, Chang-Geun; Jeong, Hye-Jin; Cho, Jun-Cheol; Lim, Kyung-Min

2013-11-01

2

Rapid and sensitive UPLC-MS-MS determination of tacrolimus in Wistar rats and human blood.  

PubMed

A simple, sensitive and high throughput ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS-MS) method was developed for the determination of tacrolimus in the whole blood of Wistar rats and humans. Sample preparation involved protein precipitation of the analyte, using sirolimus as the internal standard with ZnSO4 from 50 µL of rat blood/human blood, followed by solid-phase extraction. Chromatographic analysis was conducted on a Waters Acquity UPLC BEH C18 column (50 × 2.1 mm, 1.7 µm) using 10 mM ammonium acetate (pH 6.0) and methanol (5:95, v/v) under isocratic conditions and detection by MS-MS. Quantitation of the analytes was achieved by multiple reaction monitoring under positive ionization mode. The method was validated over a dynamic concentration range of 0.200-200 ng/mL and had a chromatographic run time of 1.2 min. The extraction recovery for tacrolimus was >96% across three quality control levels. Matrix effect was assessed by the precision (coefficient of variation) values for the calculated slopes of calibration curves from six lots of blood. The method was applied to a pre-clinical study in 25 rats and to a bioequivalence study in 20 healthy Indian subjects. The reproducibility of the assay was successfully demonstrated by the reanalysis of 80 subject samples. PMID:23264321

Upadhyay, Vivek; Trivedi, Vikas; Shah, Gaurang; Yadav, Manish; Shrivastav, Pranav S

2014-01-01

3

High-throughput quantitation of amino acids in rat and mouse biological matrices using stable isotope labeling and UPLC-MS/MS analysis.  

PubMed

Quantifying amino acids in biological matrices is typically performed using liquid chromatography (LC) coupled with fluorescent detection (FLD), requiring both derivatization and complete baseline separation of all amino acids. Due to its high specificity and sensitivity, the use of UPLC-MS/MS eliminates the derivatization step and allows for overlapping amino acid retention times thereby shortening the analysis time. Furthermore, combining UPLC-MS/MS with stable isotope labeling (e.g., isobaric tag for relative and absolute quantitation, i.e., iTRAQ) of amino acids enables quantitation while maintaining sensitivity, selectivity and speed of analysis. In this study, we report combining UPLC-MS/MS analysis with iTRAQ labeling of amino acids resulting in the elution and quantitation of 44 amino acids within 5min demonstrating the speed and convenience of this assay over established approaches. This chromatographic analysis time represented a 5-fold improvement over the conventional HPLC-MS/MS method developed in our laboratory. In addition, the UPLC-MS/MS method demonstrated improvements in both specificity and sensitivity without loss of precision. In comparing UPLC-MS/MS and HPLC-MS/MS results of 32 detected amino acids, only 2 amino acids exhibited imprecision (RSD) >15% using UPLC-MS/MS, while 9 amino acids exhibited RSD >15% using HPLC-MS/MS. Evaluating intra- and inter-assay precision over 3 days, the quantitation range for 32 detected amino acids in rat plasma was 0.90-497?M, with overall mean intra-day precision of less than 15% and mean inter-day precision of 12%. This UPLC-MS/MS assay was successfully implemented for the quantitative analysis of amino acids in rat and mouse plasma, along with mouse urine and tissue samples, resulting in the following concentration ranges: 0.98-431?M in mouse plasma for 32 detected amino acids; 0.62-443?M in rat plasma for 32 detected amino acids; 0.44-8590?M in mouse liver for 33 detected amino acids; 0.61-1241?M in mouse kidney for 37 detected amino acids; and 1.39-1681?M in rat urine for 34 detected amino acids. The utility of the assay was further demonstrated by measuring and comparing plasma amino acid levels between pre-diabetic Zucker diabetic fatty rats (ZDF/Gmi fa/fa) and their lean littermates (ZDF/Gmi fa/?). Significant differences (P<0.001) in 9 amino acid concentrations were observed, with the majority ranging from a 2- to 5-fold increase in pre-diabetic ZDF rats on comparison with ZDF lean rats, consistent with previous literature reports. PMID:24842860

Takach, Edward; O'Shea, Thomas; Liu, Hanlan

2014-08-01

4

Rapid and Sensitive UPLC-MS/MS Method for the Determination of Domperidone in Human Plasma and its Application to Pharmacokinetic Study.  

PubMed

In this study, a simple, rapid and sensitive ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method is described for determination of domperidone in human plasma samples using oxcarbazepine as the internal standard (IS). Sample preparation was accomplished through protein precipitation with methanol, and chromatographic separation was performed on an Acquity BEH C18 column (2.1?mm×50?mm, 1.7??m) with gradient profile at a flow of 0.45?mL/min. Mass spectrometric analysis was performed using a QTrap5500 mass spectrometer coupled with an electro-spray ionization (ESI) source in the positive ion mode. The MRM transition of m/z 426.3?175.2 was used to quantify for domperidone. The linearity of this method was found to be within the concentration range of 0.25-100.0?ng/mL for domperidone in human plasma. Only 1.5?min was needed for an analytical run. The method herein described was superior to previous methods and was successfully applied to the pharmacokinetic study of domperidone in healthy Chinese volunteers after oral administration. PMID:24549964

Qiu, X-J; Zheng, S-L; Wang, Y-F; Wang, R; Ye, L

2014-06-01

5

SPE-UPLC-MS/MS method for sensitive and rapid determination of aripiprazole in human plasma to support a bioequivalence study.  

PubMed

An improved and rugged UPLC-MS/MS method has been developed and validated for sensitive and rapid determination of aripiprazole in human plasma using aripiprazole-d8 as the internal standard (IS). The analyte and IS were extracted from 100 ?L of human plasma by solid-phase extraction using Phenomenex Strata-X (30 mg, 1 cc) cartridges. Chromatography was achieved on an Acquity UPLC BEH C18 (50 mm × 2.1 mm, 1.7 ?m) analytical column using methanol: 10mM ammonium formate (85:15, v/v) as the mobile phase with isocratic elution. Quantitation was done using multiple reaction monitoring in the positive ionization mode. The linearity of the method was established in the concentration range 0.05-80 ng/mL. The mean extraction recovery was greater than 96% across QC levels, while intra- and inter batch accuracy and precision (% CV) values ranged from 97.4 to 101.9% and from 1.20 to 3.72% respectively. The relative matrix effect in eight different lots of plasma samples, expressed as % CV for the calculated slopes of calibration curves was 1.08%. The stability of aripiprazole was studied under different storage conditions. The validated method was used to support a bioequivalence study of 10mg aripiprazole formulation in 36 healthy Indian subjects. PMID:23510852

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

2013-04-15

6

A sensitive UPLC-MS/MS method for simultaneous determination of eleven bioactive components of Tong-Xie-Yao-Fang decoction in rat biological matrices.  

PubMed

There is a growing concern for the sensitive quantification of multiple components using advanced data acquisition method in herbal medicines (HMs). An improved and rugged UPLC-MS/MS method has been developed and validated for sensitive and rapid determination of multiply analytes from Tong-Xie-Yao-Fang (TXYF) decoction in three biological matrices (plasma/brain tissue/urine) using geniposide and formononetin as internal standards. After solid-phase extraction, chromatographic separation was performed on a C18 column using gradient elution. Quantifier and qualifier transitions were monitored using novel Triggered Dynamic multiple reaction monitoring (TdMRM) in the positive ionization mode. A significant peak symmetry and sensitivity improvement in the TdMRM mode was achieved as compared to conventional MRM. The reproducibility (RSD%) was ?7.9% by applying TdMRM transition while the values were 6.8-20.6% for MRM. Excellent linear calibration curves were obtained under TdMRM transitions over the tested concentration ranges. Intra- and inter-day precisions (RSD%) were ?14.2% and accuracies (RE%) ranged from -9.6% to 10.6%. The validation data of specificity, carryover, recovery, matrix effect and stability were within the required limits. The method was effectively applied to simultaneously detect and quantify 1 lactone, 2 monoterpene glucosides, 1 alkaloid, 5 flavonoids and 2 chromones in plasma, brain tissue and urine after oral administration of TXYF decoction. In conclusion, this new and reliable method is beneficial for quantification and confirmation assays of multiply components in complex biological samples. PMID:24295908

Li, Tian-xue; Hu, Lang; Zhang, Meng-meng; Sun, Jian; Qiu, Yue; Rui, Jun-qian; Yang, Xing-hao

2014-01-01

7

Use of a sensitive and robust UPLC-MS/MS method to determine the gender-dependent pharmacokinetics in rats of emodin and its glucuronide  

PubMed Central

The purpose of this research was to set up a sensitive and consistent UPLC-UV and UPLCMS/MS method to analyze emodin and its glucuronidated metabolite, and to determine how gender differences affect its pharmacokinetic behaviors. In addition, a breast cancer resistance protein inhibitor dipyridamole was used to test how significant the absolute oral biovailabilty of emodin or its glucuronide is increased. A sensitive and fast UPLC-MS/MS method was successfully applied to determine emodin and its metabolite in male and female SD rat plasma. The absolute oral bioavailability of emodin was extremely low whether in male rats (7.5%) and female rats (5%). Following a single intravenous injection of 4 mg/kg emodin, the emodin plasma concentration-time data fit for a good two-compartment model either in male or female SD rats. The t1/2? were 13.26±6.28min (male rats) and 13.52±7.28min (female rats). The t1/2? were 187.38±0.16min (male rats) and 118.50±83.09min (female rats). Emodin showed significant gender differences in i.v. PK profiles with higher AUC values in male (422.71 ± 163.40 mg*?g/ml) than female (282.52 ± 98.42 mg*?g/ml) SD rats (n=6). Emodin glucuronide was suggested a good fit for single compartmental model for the plasma emodin metabolite concentrations. The t1/2Ke were 167.40±50.91min(male rats) and 251.31±114.20min (female rats), the area under the curve (AUC0-?, i.v.) were 2210.02 ± 950.09 mg*?g/ml and 1054.42 ± 290.31 mg*?g/ml (female rats)(n=6). There was no good fit for any PK compartmental model for the plasma concentration-time data for single dose oral administration of emodin (8mg/kg) and its metabolite. Analyzing the oral PK data using non-compartmental model, Cmax, Tmax and AUC0-?, p.o. of emodin in male rats were: 0.31±0.094 were ?g/ml, 18.00±6.71min and 65.76±34.77 mg*?g/ml respectively; whereas Cmax, Tmax and AUC0-?, p.o. of emodin in female rats were: 0.039±0.011 ?g/ml, 18.75±7.51min and 33.82±4.09 mg*?g/ml respectively. The parameters of emodin glucuronide were significant different with emodin, the Cmax, Tmax and AUC0-?, p.o of emodin glucuronide in male rats were 6.69±1.06 ?g/ml, 240min and 2261.89±655.87 mg*?g/ml respectively, in female rats, the Cmax, Tmax and AUC0-?, p.o. were 1.81±0.58 ?g/ml, 60min and 458.50±373.29 mg*?g/ml respectively. The absolute bioavailability of emodin glucuronide was 60% (male rats) and 15% (female rats). The absolute bioavailability of emodin was no significant changed (7.3%) in male rats by using dipyridamole, the bioavailability of metabolite of emodin was significant declined to 14.6%.

Liu, Wei; Gao, Song; Zheng, Zhijie; Liu, Xi; Ye, Ling; Yang, Zhen; Hu, Ming; Liu, Zhongqiu

2014-01-01

8

Simultaneous determination of genistein and its four phase II metabolites in blood by a sensitive and robust UPLC-MS/MS method: application to an oral bioavailability study of genistein in mice  

PubMed Central

The purpose of this research was to develop a sensitive and reproducible UPLC-MS/MS method to simultaneously quantify genistein, genistein-7-O-glucuronide (G-7-G), genistein-4’-O-glucuronide (G-4’-G), genistein-4’-O-sulfate (G-4’-S) and genistein-7-Osulfate (G-7-S) in mouse blood samples. After the method was fully validated over a wide linear range, it was applied to quantify the levels of genistein and its metabolites in a mouse bioavailability study. The linear response range were 19.5–10,000 nM for genistein, 12.5–3,200 nM for G-7-G, 20–1280 nM for G-4’-G, 1.95–2,000 nM for G-4’-S, and 1.56–3,200 nM for G-7-S, respectively. The lower limit of quantification (LLOQ) was 4.88, 6.25, 5, 0.98 and 0.78 nM for genistein, G-7-G, G-4’-G, G-4’-S and G-7-S, respectively. Only 20 µl mouse blood sample from i.v. and p.o. administration were needed for analysis because of the high sensitivity of the method. The intra- and inter-day variance is less than 15% and accuracy is within 85–115%. The analysis was finished within 4.5 min. The applicability of this assay was demonstrated and successfully applied for bioavailability study in FVB mouse after i.v. and p.o. administration of 20 mg/kg of genistein, and its oral bioavailability was ~24%.

Yang, Zhen; Zhu, Wei; Gao, Song; Xu, Haiyan; Wu, Baojian; Kulkarni, Kaustubh; Singh, Rashim; Tang, Lan; Hu, Ming

2012-01-01

9

Simultaneous determination of antidementia drugs in human plasma: procedure transfer from HPLC-MS to UPLC-MS/MS.  

PubMed

A previously developed high performance liquid chromatography mass spectrometry (HPLC-MS) procedure for the simultaneous determination of antidementia drugs, including donepezil, galantamine, memantine, rivastigmine and its metabolite NAP 226-90, was transferred to an ultra performance liquid chromatography system coupled to a tandem mass spectrometer (UPLC-MS/MS). The drugs and their internal standards ([(2)H(7)]-donepezil, [(13)C,(2)H(3)]-galantamine, [(13)C(2),(2)H(6)]-memantine, [(2)H(6)]-rivastigmine) were extracted from 250 ?L human plasma by protein precipitation with acetonitrile. Chromatographic separation was achieved on a reverse phase column (BEH C18 2.1 mm × 50 mm; 1.7 ?m) with a gradient elution of an ammonium acetate buffer at pH 9.3 and acetonitrile at a flow rate of 0.4 mL/min and an overall run time of 4.5 min. The analytes were detected on a tandem quadrupole mass spectrometer operated in positive electrospray ionization mode, and quantification was performed using multiple reaction monitoring. The method was validated according to the recommendations of international guidelines over a calibration range of 1-300 ng/mL for donepezil, galantamine and memantine, and 0.2-50 ng/mL for rivastimgine and NAP 226-90. The trueness (86-108%), repeatability (0.8-8.3%), intermediate precision (2.3-10.9%) and selectivity of the method were found to be satisfactory. Matrix effects variability was inferior to 15% for the analytes and inferior to 5% after correction by internal standards. A method comparison was performed with patients' samples showing similar results between the HPLC-MS and UPLC-MS/MS procedures. Thus, this validated UPLC-MS/MS method allows to reduce the required amount of plasma, to use a simplified sample preparation, and to obtain a higher sensitivity and specificity with a much shortened run-time. PMID:22410501

Noetzli, Muriel; Ansermot, Nicolas; Dobrinas, Maria; Eap, Chin B

2012-05-01

10

Depletion of urinary zilpaterol residues in horses as measured by ELISA and UPLC-MS/MS.  

PubMed

Three horses were dosed with dietary zilpaterol and the urine concentrations measured from withdrawal day 0 to withdrawal day 21. The analyses were carried out using both enzyme-linked immunosorbent assay (ELISA) and an ultraperformance liquid chromatography with triple-quadrupole-tandem mass spectrometric detection (UPLC-MS/MS). The UPLC-MS/MS method was developed to provide rapid analysis with positive analyte identification by following three product ions and computing the two independent ion ratios. When urinary zilpaterol concentrations were between 0.2 and 2 ng/mL, the ELISA had interday recoveries of 114-120% with coefficients of variation (CV) of <22%; intraday recoveries were 79-111% with CVs of <13%. For urinary zilpaterol concentrations of 0.4-40 ng/mL the UPLC-MS/MS method had interday recoveries of 94-104% with CVs of <8%; intraday recoveries were 97-102% with CVs of < or = 7.5%. Correlation analysis demonstrated that the ELISA and UPLC-MS/MS methods returned essentially the same results, especially at urinary zilpaterol concentrations below 2000 ng/mL. Urinary excretion peaked rapidly after dosing between 5300 and 10800 ng/mL (UPLC-MS/MS) or between 5900 and 17900 ng/mL (ELISA) for the different horses, much higher than observed in other species. Urinary zilpaterol concentrations declined rapidly to below 3000 ng/mL within 24 h of study day 1. After about 5 days, zilpaterol elimination slowed markedly, taking nearly 10 days for an order of magnitude decrease. The analytical methods were able to detect zilpaterol in the urine even at withdrawal day 21, demonstrating the sensitivity of each analytical method and the slow rate of zilpaterol depuration from horses. PMID:20218607

Shelver, Weilin L; Thorson, Jennifer F; Hammer, Carolyn J; Smith, David J

2010-04-14

11

Simple and rapid quantitation of 21 bile acids in rat serum and liver by UPLC-MS-MS: effect of high fat diet on glycine conjugates of rat bile acids.  

PubMed

In this report, we present a simple and rapid method for analysis of 21 kinds of bile acids and the conjugates in rat serum and liver samples by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) in the negative ionization mode, using cholic-2, 2, 4, 4-d4 acid as internal standard. After liquid-liguid extraction from serum and liver samples, specimens were analyzed by UPLC equipped with an Acquity TQD tandem quadrupole mass spectrometer. All of the 21 bile acids were sufficiently separated within 5 min. For most bile acids, calibration curves showed good linearities in the range of 0.25 to 5000 ng/mL for serum samples, 2.5 ng/g to 50 microg/g for liver samples. The limits of detection (LOD) were estimated to be less than 0.25 to 7.5 ng/mL in serum, less than 2.5 to 10 ng/g in liver samples. The present method was validated with respect to repeatability; the coefficient of variation (CV) values were less than 26.7% in the serum and 25.9% in the liver. In the animal study, we compared 21 bile acids in the serum and liver samples of the stroke-prone spontaneously hypertensive (SHRSP) rats fed with control (SP) diet or high-fat and high-cholesterol-containing (HFC) diet. By feeding with HFC diet, the glycine conjugates of some bile acids significantly increased and the taurine conjugate of ulsodeoxicolate (TUDC) decreased in serum and liver samples. Our results suggest that the change of bile acid profiles could be applied for the diagnosis of non-alcoholic fatty liver disease (NAFLD). PMID:23544269

Suzuki, Yudai; Kaneko, Rina; Nomura, Mina; Naito, Hisao; Kitamori, Kazuya; Nakajima, Tamie; Ogawa, Tadashi; Hattori, Hideki; Seno, Hiroshi; Ishii, Akira

2013-02-01

12

New perspectives in bio-analytical techniques for preclinical characterization of a drug candidate: UPLC-MS/MS in in vitro metabolism and pharmacokinetic studies.  

PubMed

Lead optimization requires rapid bio-analytical turnover for the generation of early absorption, distribution, metabolism, excretion (ADME) and pharmacokinetics (PK) data maintaining a high quality level. Therefore, one of the major challenges in the bio-analytical field is to achieve faster and more sensitive quantification protocols. In the present communication, a comparison between HPLC and ultra performance liquid chromatography (UPLC) performances in terms of sensitivity and resolution is shown using a pharmakokinetic study and a metabolism study as models. The studies highlight the features of the new technology and the resulting impact in the PK throughput and in the characterization of isomeric metabolites using UPLC/MS/MS technique. PMID:17236736

Pedraglio, Samuele; Rozio, Marco Giulio; Misiano, Paola; Reali, Veronica; Dondio, Giulio; Bigogno, Chiara

2007-07-27

13

Profiling counterfeit Cialis, Viagra and analogs by UPLC-MS.  

PubMed

In this work, the chemical profile of 43 commercial samples of tablets for male erectile dysfunction (Viagra, Cialis, Lazar, Libiden, Maxfil, Plenovit, Potent 75, Rigix, Vimax, Pramil 75 and Pramil) and 65 counterfeit samples (Viagra and Cialis) were obtained from UPLC-MS data. Methanol extracts of crushed tablets were investigated by ultra performance liquid chromatography (UPLC) with diode array detection (DAD) coupled with eletrospray ionization in the positive ion mode (ESI(+)) quadrupole time-of-flight (Q-Tof) mass spectrometry (MS). A validated method was employed for the simultaneous determination of sildenafil citrate (SLD) and tadalafil (TAD). The ultra-chromatograms obtained with method provide high resolution of MS, and are a quick (less to 1.5 min) and reliable tool in the distinction between authentic and counterfeit tablets. It was observed in most cases the presence of other active pharmaceutical ingredients (APIs) than specified on the package (TAD and SLD). Additionally, high concentrations of TAD and SLD were detected in counterfeit samples when compare with observed values for a typical commercial product. Chemometric methods were employed and the samples were grouped in five groups as function of API content. PMID:23683904

Ortiz, Rafael S; Mariotti, Kristiane de Cássia; Holzschuh, Maribete H; Romão, Wanderson; Limberger, Renata P; Mayorga, Paulo

2013-06-10

14

Simultaneous determination of plasma epinephrine and norepinephrine using an integrated strategy of a fully automated protein precipitation technique, reductive ethylation labeling and UPLC-MS/MS.  

PubMed

A novel, automated, simple, sensitive, specific, accurate, precise and high-throughput liquid chromatography tandem mass spectrometry (LC-MS/MS)-based method has been developed for simultaneous determination of epinephrine (E) and norepinephrine (NE) in plasma by using the combination of a fully automated protein precipitation technique for plasma sample preparation, reductive ethylation labeling with UPLC-MS/MS. A simple protein precipitation procedure was used to clean up 50 microL calibration samples prepared in stripped human plasma and 50 microL quality control plasma samples containing 25 microL plasma and 25 microL stabilizing additives. The supernatants were subsequently dried down and then reconstituted with commercially available and cost-effective reductive ethylation labeling reagents, followed by UPLC-MS/MS analysis. All liquid handling during sample preparation was automated using a Hamilton MicroLab Star Robotic workstation, which included the preparation of standards and quality control samples, shaking of 96-well plates, adding and transferring liquids. Processing time, which included the preparation of standards and quality control samples, protein precipitation and reductive ethylation labeling, is less than 2 h per 96-well plate. The chromatographic run time is 3.5 min per sample. The limits of detection of UPLC-MS/MS-based methods for E and NE, with/without reductive ethylation labeling, are 0.025/0.40 and 0.025/2.00 ng mL(-1), respectively. Reductive ethylation labeling of amino groups of E and NE affords 16 and 80 times increased detection sensitivity of corresponding native counterparts during the UPLC-MS/MS analysis. The linearity of this method was established from 0.05 to 25 ng mL(-1) for E and NE with accuracy and precision within 15% at all concentrations. The intra-run and inter-run assay accuracy (%RE) and coefficient of variations (CV%) are all within 15% for all QC samples prepared in commercially purchased plasma samples. PMID:20685421

Ji, Chengjie; Walton, Justin; Su, Yi; Tella, Max

2010-06-18

15

Assessment of oxidative damage to proteins and DNA in urine of newborn infants by a validated UPLC-MS/MS approach.  

PubMed

The assessment of oxidative stress is highly relevant in clinical Perinatology as it is associated to adverse outcomes in newborn infants. This study summarizes results from the validation of an Ultra Performance Liquid Chromatography-tandem Mass Spectrometry (UPLC-MS/MS) method for the simultaneous quantification of the urinary concentrations of a set of endogenous biomarkers, capable to provide a valid snapshot of the oxidative stress status applicable in human clinical trials, especially in the field of Perinatology. The set of analytes included are phenylalanine (Phe), para-tyrosine (p-Tyr), ortho-tyrosine (o-Tyr), meta-tyrosine (m-Tyr), 3-NO2-tyrosine (3NO2-Tyr), 3-Cl-tyrosine (3Cl-Tyr), 2'-deoxyguanosine (2dG) and 8-hydroxy-2'-deoxyguanosine (8OHdG). Following the FDA-based guidelines, appropriate levels of accuracy and precision, as well as adequate levels of sensitivity with limits of detection (LODs) in the low nanomolar (nmol/L) range were confirmed after method validation. The validity of the proposed UPLC-MS/MS method was assessed by analysing urine samples from a clinical trial in extremely low birth weight (ELBW) infants randomized to be resuscitated with two different initial inspiratory fractions of oxygen. PMID:24695409

Kuligowski, Julia; Torres-Cuevas, Isabel; Quintás, Guillermo; Rook, Denise; van Goudoever, Johannes B; Cubells, Elena; Asensi, Miguel; Lliso, Isabel; Nuñez, Antonio; Vento, Máximo; Escobar, Javier

2014-01-01

16

Assessment of Oxidative Damage to Proteins and DNA in Urine of Newborn Infants by a Validated UPLC-MS/MS Approach  

PubMed Central

The assessment of oxidative stress is highly relevant in clinical Perinatology as it is associated to adverse outcomes in newborn infants. This study summarizes results from the validation of an Ultra Performance Liquid Chromatography–tandem Mass Spectrometry (UPLC-MS/MS) method for the simultaneous quantification of the urinary concentrations of a set of endogenous biomarkers, capable to provide a valid snapshot of the oxidative stress status applicable in human clinical trials, especially in the field of Perinatology. The set of analytes included are phenylalanine (Phe), para-tyrosine (p-Tyr), ortho-tyrosine (o-Tyr), meta-tyrosine (m-Tyr), 3-NO2-tyrosine (3NO2-Tyr), 3-Cl-tyrosine (3Cl-Tyr), 2?-deoxyguanosine (2dG) and 8-hydroxy-2?-deoxyguanosine (8OHdG). Following the FDA-based guidelines, appropriate levels of accuracy and precision, as well as adequate levels of sensitivity with limits of detection (LODs) in the low nanomolar (nmol/L) range were confirmed after method validation. The validity of the proposed UPLC-MS/MS method was assessed by analysing urine samples from a clinical trial in extremely low birth weight (ELBW) infants randomized to be resuscitated with two different initial inspiratory fractions of oxygen.

Kuligowski, Julia; Torres-Cuevas, Isabel; Quintas, Guillermo; Rook, Denise; van Goudoever, Johannes B.; Cubells, Elena; Asensi, Miguel; Lliso, Isabel; Nunez, Antonio; Vento, Maximo; Escobar, Javier

2014-01-01

17

Determination of pergolide in horse plasma by UPLC-MS/MS for pharmacokinetic applications.  

PubMed

Pergolide, an ergot-derived dopamine D2 receptor agonist, is used extensively as an orally administered treatment for pituitary pars intermedia dysfunction (PPID) in horses. One of the barriers associated with pergolide determinations in plasma for pharmacokinetic applications has been the technically demanding requirement for sensitivity. The objective of our work was to develop a simple assay for the determination of pergolide in plasma and demonstrate its potential application in the study of pergolide pharmacokinetics (PK) in horses. A UPLC-MS/MS assay was developed with a simple sample preparation involving methanol protein precipitation and injection of supernatant. The assay was applied to samples from a horse dosed with 10mg pergolide (as the mesylate salt) by nasogastric intubation. Plasma samples were collected over a 48h period. The assay demonstrated performance sufficient to enable application to low level PK studies. Within-batch precision and accuracy were within acceptance criteria; precision was less than 10% RSD (n=5) and accuracy was -7.3% at 0.014ng/mL, the lower limit of quantification was 0.006ng/mL and the method detection limit was 0.002ng/mL. In the treated horse, Cmax was 0.40ng/mL and the assay easily allowed determination of plasma levels in the elimination phase to 48h. In conclusion, this assay using UPLC-MS/MS and methanol protein precipitation easily meets the challenging demands of pergolide analyses in plasma. PMID:24549007

Jacobson, Glenn A; Pirie, Adam; Edwards, Scott; Hughes, Kristopher J; Rendle, David I; Davies, Noel W

2014-06-01

18

A Fast One Step Extraction and UPLC-MS/MS Analysis for E2/D2 Series Prostaglandins and Isoprostanes  

PubMed Central

Prostaglandins (PG) and isoprostanes (iso-PG) may be derived through cyclooxygenase or free radical pathways and are important signaling molecules that are also robust biomarkers of oxidative stress. Their quantification is important for understanding many biological processes where PG, iso-PG, or oxidative stress are involved. One of the common methods for PG and iso-PG quantifications is LC-MS/MS that allows a highly selective, sensitive, simultaneous analysis for prostanoids without derivatization. However, the currently used LC-MS/MS methods require a multi-step extraction and a long (within an hour) LC separation to achieve simultaneous separation and analysis of the major iso-PG. The developed and validated for brain tissue analysis one-step extraction protocol and UPLC-MS/MS method significantly increases the recovery of the PG extraction up to 95%, and allows for a much faster (within 4 min) major iso-PGE2 and -PGD2 separation with 5 times narrower chromatographic peaks as compared to previously used methods. In addition, it decreases the time and cost of analysis due to one-step extraction approach performed in disposable centrifuge tubes. All together, this significantly increases the sensitivity, and the time and cost efficiency of the PG and iso-PG analysis.

Brose, Stephen A.; Baker, Andrew G.; Golovko, Mikhail Y.

2013-01-01

19

Application of label-free shotgun nUPLC-MS(E) and 2-DE approaches in the study of Botrytis cinerea mycelium.  

PubMed

The phytopathogenic fungus Botrytis cinerea infects more than different 200 plant species and causes substantial losses in numerous crops. The B05.10 and T4 wild-type strain genomes have been recently sequenced, becoming a model system for necrotrophic pathogens, as well as opening up new alternatives in functional genomics, such as proteomics. We analyzed B. cinerea mycelium from these two wild-type strains, introducing label-free shotgun nUPLC-MS(E) methodology to complement the 2-DE-MS-based approach. We assessed the label-free nUPLC-MS(E) methodology for protein identification and quantification using five mycelium protein dilutions. A total of 225 and 170 protein species were identified by nUPLC-MS(E) in the B05.10 and T4 strains, respectively. Moreover, 129 protein species were quantified in both strains. Significant differences in protein abundance were found in 15 more abundant and 16 less abundant protein species in the B05.10 strain compared to the T4 strain. Twenty-nine qualitative and 15 significant quantitative differences were found using 2-DE. The label-free nUPLC-MS(E) was a reliable, reproducible and sensitive method for protein identification and quantification to study the B. cinerea mycelial proteome. Results obtained by gel-based and gel-free complementary approaches allow a deeper characterization of this fungus, as well as the identification of potential virulence factors. PMID:23627497

Gonzalez-Fernandez, Raquel; Aloria, Kerman; Arizmendi, Jesus M; Jorrin-Novo, Jesus V

2013-06-01

20

Determination of cannabinoids in whole blood by UPLC-MS-MS.  

PubMed

An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method was developed and validated for the simultaneous determination of Delta(9)-tetrahydrocannabinol (THC), 11-hydroxy-Delta(9)-tetrahydrocannabinol (11-OH-THC), and 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in whole blood. Samples were prepared by protein precipitation followed by solid-phase extraction. Data were acquired using positive electrospray ionization and multiple reaction monitoring. Two transitions were selected for THC (m/z 315.0 > 193.0 and m/z 315.0 > 122.7) and THC-COOH (m/z 345.0 > 299.0 and m/z 345.0 > 327.0), and one transition was chosen for 11-OH-THC (m/z 331.0 > 313.0). Deuterated analogues of each analyte were used as internal standards for quantification. Run time was 10 min. Limits of quantification (LOQ) were 0.05 ng/mL for THC, 0.1 ng/mL for 11-OH-THC, and 0.2 ng/mL for THC-COOH. Linearity was established from LOQ to 50 ng/mL for each substance (r(2) always > 0.999). Accuracy ranged from 96 to 106%, and imprecision was less than 10% for all analytes. The UPLC-MS-MS method was found to be sensitive, specific, and rapid because it requires no derivatization step. It can be an alternative to gas chromatography-mass spectrometry for the determination of cannabinoids in whole blood. PMID:18544220

Jamey, Carole; Szwarc, Esther; Tracqui, Antoine; Ludes, Bertrand

2008-06-01

21

A rapid and sensitive UPLC-MS/MS method for quantification of two caffeoylquinic acids and four main active components in rat plasma after an intravenous administration of Qingkailing injection and its application to a pharmacokinetic study.  

PubMed

Qingkailing (QKL) injection, a modified modern Chinese medicine preparation, is widely used in the clinic for its significant antipyretic and anti-inflammatory effects, but its serious adverse drug reactions have attracted more and more attention. Series of caffeoylquinic acids in QKL are widely suspected to be the allergens responsible for these adverse drug reactions. Therefore, pharmacokinetic studies of the caffeoylquinic acids are needed. In this paper, a simple, rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of chlorogenic acid, neochlorogenic acid, baicalin, geniposide, cholic acid and hyodeoxycholic acid in rat plasma. Chromatographic separation was achieved on a BEH C18 column by a gradient elution at a flow rate of 0.40?mL/min in only 6.0?min. All analytes were monitored by multiple reaction monitoring mode with negative electrospray ionization. The calibration curves of these analytes were all linear (r?>?0.9978) over wide concentration ranges. The intra- and inter- day precisions (relative standard deviations) were within 14.3% and accuracy (relative error) ranged from -6.8 to 4.8%. The mean recoveries ranged from 74.5 to 105.6%. This validated method was successfully applied to the pharmacokinetic study of the six analytes in rats following an intravenous administration of QKL injection. Copyright © 2013 John Wiley & Sons, Ltd. PMID:24185835

Peng, Long; Gao, Xiaoyan; Song, Yuelin; Zhao, Longshan; Guo, Mingxing; Su, Jiankun; Zhang, Li; Liu, Haiyu

2014-05-01

22

[Metabolites and metabolic pathways of mesaconitine in rat liver microsomal investigated by using UPLC-MS/MS method in vitro].  

PubMed

Mesaconitine was incubated with rat liver microsomes in vitro. The metabolites of mesaconitine in rat liver microsomes were identified by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method with high resolution power. A typical reaction mixture of 100 mol L-1 Tris-HCI buffer (pH 7.4) containing 0.5 gL-1 microsomal protein and 50 micro molL-1 mesaconitine was prepared. The above reaction mixture was divided into six groups, and the volume of each group was 200 micro L. The incubation mixture was pre-incubated at 37 degrees C for 2 min and the reactions were initiated by adding NADPH generating system. After 90 min incubation at 37 degrees C, 200 micro L of acetonitrile was added to each group to stop the reaction. The metabolites of mesaconitine were investigated by UPLC-MS/MS method. Mesaconitine and 6 metabolites M1-M6 were found in the incubation system. The structures were characterized according to the data from MS/MS spectra and literatures. The metabolic reactions of mesaconitine in rat liver microsomes included the demethylation, deacetylation, dehydrogenation and hydroxylation. The major metabolic pathways of mesaconitine in rat liver microsomes were determined by UPLC-MS/MS on multiple reaction monitoring (MRM) mode combined with specific inhibitors of cytochrome P450 (CYP) isoforms, including alpha-naphthoflavone (CYP1A2), quinine (CYP2D), diethyldithiocarbamate (CYP2E1), ketoconazole (CYP3A) and sulfaphenazole (CYP2C), separately. Mesaconitine was mainly metabolized by CYP3A. CYP2C and CYP2D were also more important CYP isoforms for the metabolism reactions of mesaconitine, but CYP1A2 and CYP2E1 haven't any contribution to MA metabolism in rat liver microsomes. PMID:24689241

Bi, Yun-Feng; Liu, Shu; Zhang, Rui-Xing; Song, Feng-Rui; Liu, Zhi-Qiang

2013-12-01

23

Determination of Cefaclor by UPLC-MS-MS for a Chinese Pharmacokinetic Study.  

PubMed

A novel method has been developed for the determination of cefaclor in human plasma by ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-MS-MS). The plasma was treated by a single step of protein precipitation with acetonitrile. The chromatographic separation was performed on a Waters Acquity UPLC BEH C18 (2.1 × 100 mm, 1.7 µm) with a gradient mobile phase consisting of 0.1% formic acid and acetonitrile at a flow rate of 0.4 mL/min. The analyses were conducted by multiple reaction monitoring using the precursor-to-product combinations of m/z 367.5 ? 173.8 (cefaclor) and m/z 454.1 ? 160.3 (internal standard). Validation results indicated that the lower limit of quantification was 2 ng/mL and the assay exhibited a linear range of 2-10,000 ng/mL. Quality control samples (5, 200 and 5,000 ng/mL) in five replicates from three different runs of analysis demonstrated an intra-assay precision (relative standard deviation) of 3.7-10.7%, an inter-assay precision of 5.8-8.9%, and an overall accuracy of < 15%. A sensitive and specific method for quantifying cefaclor in human plasma has been devised and successfully applied to a pharmacokinetic study. PMID:23839802

Huang, Chenrong; Wang, Wei; Miao, Liyan

2014-08-01

24

Detection of ?-methylphenethylamine, a novel doping substance, by means of UPLC/MS/MS.  

PubMed

Novel substances of expected doping activity are constantly introduced to the market. ?-Methylphenethylamine (BMPEA) is classified as a doping agent by the World Anti-Doping Agency as it is a positional isomer of amphetamine. In this work, the development and application of a simple and rapid analytical procedure that enables discrimination between both isomers is described. The analytes of interest were extracted from urine by a two-step liquid-liquid extraction and then analyzed by UPLC/MS/MS under isocratic conditions. The entire analytical procedure was validated by evaluating its selectivity, discrimination capabilities, carry-over, sensitivity, and influence of matrix effects on its performance. Application of the method resulted in detection of BMPEA in eight anti-doping samples, including the first report of adverse analytical finding regarding its use. Further analysis showed that BMPEA may be eliminated unchanged along with its phase II conjugates, the hydrolysis of which may considerably improve detection capabilities of the method. Omission of the hydrolysis step may therefore, produce false-negative results. Testing laboratories should also carefully examine their LC/MS/MS-based amphetamine and BMPEA findings as both isomers fragment yielding comparable collision-induced dissociation spectra and their insufficient chromatographic separation may result in misidentification. This is of great importance in case of forensic analyses as BMPEA is not controlled by the public law, and its manufacturing, distribution, and use are legal. PMID:24633566

Cho?bi?ski, Piotr; Wicka, Mariola; Kowalczyk, Katarzyna; Jarek, Anna; Kaliszewski, Pawe?; Pokrywka, Andrzej; Bulska, Ewa; Kwiatkowska, Dorota

2014-06-01

25

Photocatalytic degradation of hexazinone and its determination in water via UPLC-MS/MS.  

PubMed

Degradation of hexazinone has been investigated by means of photocatalysis of mixed-phase crystal nano-TiO(2). Influences of adsorption, amount of nano-TiO(2), pH and irradiation time on the photocatalytic process are studied. Results show that hexazinone is totally degraded within 40min of irradiation under pH neutral conditions. This compares favorably with Degussa P25 TiO(2) when conducted under the same experimental conditions. Preliminary photocatalytic kinetic information for hexazinone degradation is proposed. First order kinetics is obtained for the adsorption and photocatalytic degradation reactions, which fit the Langmuir-Hinshelwood model. A rapid, sensitive and accurate UPLC-MS/MS technique is developed and utilized to determine the level of hexazinone in water in support of the degradation kinetics study. The results indicate a limit of detection (LOD) at 0.05?g/l and the recoveries between 90.2 and 98.5% with relative standard deviations (RSD) lower than 12%. A LC-MS/MS technique is used to trace the degradation process. Complete degradation is achieved into final products including nontoxic water, carbon dioxide and urea. A probable pathway for the total photocatalytic degradation of hexazinone is proposed. PMID:22551636

Mei, Mei; Du, Zhenxia; Xu, Ruifen; Chen, Yun; Zhang, Haojie; Qu, Shuping

2012-06-30

26

Determination of cephalomannine in rat plasma by gradient elution UPLC-MS/MS method.  

PubMed

A rapid, sensitive and selective ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of cephalomannine in rat plasma. Sample preparation was accomplished through a simple one-step deproteinization procedure with 0.2mL of perchloric acid-methanol (1:9, v/v) to a 0.1mL plasma sample. Plasma samples were separated by UPLC on an Acquity UPLC BEH C18 column using a mobile phase consisting of acetonitrile-0.1% formic acid in water with gradient elution. The total run time was 2.0min and the elution of cephalomannine was at 1.60min. The detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction-monitoring (MRM) mode using the respective transitions m/z 832.8?264.1 for cephalomannine and m/z 812.6?286.0 for 10-DAT (internal standard), respectively. The calibration curve was linear over the range of 10-2000ng/mL with a lower limit of quantitation (LLOQ) of 10ng/mL. Mean recovery of cephalomannine in plasma was in the range of 80.9-85.3%. Intra-day and inter-day precision were both <11.2%. This method was successfully applied in pharmacokinetic study after intravenous administration of 5.0mg/kg cephalomannine in rats. PMID:24929960

Wang, Xin-Shuai; Sun, Jia-Chun; Yang, Rui-Na; Ren, Jing; Liang, Shuo; Sun, Ming; Wang, Ying-Fei; Gao, She-Gan

2014-07-15

27

EtG/EtS in Urine from sexual assault victims determined by UPLC-MS-MS.  

PubMed

In cases of sexual assault, victims often present too late for the detection of ethanol in biological samples. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method was developed and validated for the determination of ethyl glucuronide (EtG) and ethyl sulfate (EtS) in urine. Sample preparation prior to UPLC-MS-MS analysis was a simple sample dilution. The calibration ranges were 0.2-20 mg/L, and between-assay relative standard deviations were in the range of 0.7-7.0% at concentrations of 0.3, 3.0 and 7.0 mg/L. Urine samples were analyzed from 59 female patients presenting to the Sexual Assault Centre at St. Olav University Hospital in Trondheim, Norway between November 2010 and October 2011. EtG and EtS results were fully concordant, and positive in 45 of the 48 cases with self-reported alcohol intake. In contrast, ethanol was detectable in only 20 of these cases, corresponding to sensitivities of 94 and 42%, respectively. Of the patients reporting no alcohol intake, none had positive EtG/EtS findings. These data show that analysis of EtG and EtS greatly increases the detection window of alcohol ingestion in cases of sexual assault, and may shed additional light on the involvement of ethanol in such cases. The victims' self-reported intake of alcohol seems to be reliable in this study, according to the EtG/EtS findings. PMID:23467259

Hegstad, Solfrid; Helland, Arne; Hagemann, Cecilie; Michelsen, Lisbeth; Spigset, Olav

2013-05-01

28

Reliable quantification of bisphenol A and its chlorinated derivatives in human urine using UPLC-MS/MS method.  

PubMed

Bisphenol A (BPA), a widespread man-made chemical classified as an endocrine disruptor, is increasingly considered as a major cause of concern for human health. Chlorine present in drinking water may react with BPA to form chlorinated derivatives (ClxBPA), which have demonstrated a heightened level of estrogenic activity. If many epidemiological studies report that more than 90% of people have detectable BPA levels in their urine, then no such study has been undertaken regarding ClxBPA. The purpose of this work is to propose a highly sensitive and accurate analytical method adapted to large-scale biomonitoring studies aimed at assessing exposure to BPA and ClxBPA through the use of human urine. To achieve this, we have comprehensively validated a method using salting-out assisted liquid/liquid extraction (SALLE) coupled to UPLC-MS/MS and isotope dilution quantification, to measure unconjugated BPA and ClxBPA in human urine according to the accepted guidelines. Deutered BPA as well as deutered 2,2'-DCBPA was used as internal standards. The matrix calibration curve ranged from 0.05 to 1.60ngmL(-1) and from 0.5 to 16.0ngmL(-1) for ClxBPA and BPA respectively, and provided good linearity (r²>0.99). This method was precise (the intra- and inter-day coefficients of variation were <20% at three different concentrations: 0.05ngmL(-1), 0.2ngmL(-1), 0.8ngmL(-1) and 0.5ngmL(-1), 2ngmL(-1), 8ngmL(-1) for ClxBPA and BPA, respectively) and accurate (bias ranged from -13% to +12%). The limit of quantification, validated at 0.05ngmL(-1) and 0.5ngmL(-1) for ClxBPA and BPA respectively when using 300µL of urine, was found to be suitable for the concentration existing in real samples. The matrix effect and the BPA cross-contamination were also investigated in this study. The analytical method developed in this study is in accordance with the requirements applicable to biomonitoring of BPA and ClxBPA in human urine. PMID:24840445

Venisse, N; Grignon, C; Brunet, B; Thévenot, S; Bacle, A; Migeot, V; Dupuis, A

2014-07-01

29

Diethylation labeling combined with UPLC/MS/MS for simultaneous determination of a panel of monoamine neurotransmitters in rat prefrontal cortex microdialysates.  

PubMed

The primary challenge associated with the development of an LC/MS/MS-based assay for simultaneous determination of biogenic monoamine neurotransmitters such as norepinephrine (NE), dopamine (DA), serotonin (5-HT), and normetanephrine (NM) in rat brain microdialysates is to improve detection sensitivity. In this work, a UPLC/ MS/MS-based method combined with a diethyl labeling technique was developed for simultaneous determination of a panel of monoamines in rat prefrontal cortex microdialysates. The chromatographic run time is 3.5 min/ sample. The limits of detection of the UPLC/MS/MS-based method for NE, DA, 5-HT/ and NM, with/without diethyl labeling of monoamines, are 0.005/0.4 (30/2367 pM), 0.005/0.1 (33/653 pM), 0.005/0.2 (28/1136 pM), and 0.002/0.2 ng/mL (11/1092 pM), respectively. Diethyl labeling of amino groups of monoamines affords 20-100 times increased detection sensitivity of corresponding native monoamines during the UPLC/MS/MS analysis. This could result from the following: (1) improved fragmentation patterns; (2) increased hydrophobicity and concomitantly increased ionization efficiency in ESI MS and MS/MS analysis; (3) reduced matrix interference. This labeling reaction employs a commercially available reagent, acetaldehyde-d4, to label the amine groups on the monoamines via reductive amination. It is also simple, fast (approximately 25-min reaction time), specific, and quantitative under mild reaction conditions. Data are also presented from the application of this assay to monitor the drug-induced changes of monoamine concentrations in rat prefrontal cortex microdialysate samples followed by administration of SKF 81297, a selective D1 dopamine receptor agonist known to elevate the extracellular level of the neurotransmitters DA and NE in the central nervous system. PMID:19551941

Ji, Chengjie; Li, Wenlin; Ren, Xiao-Dan; El-Kattan, Ayman F; Kozak, Rouba; Fountain, Scott; Lepsy, Christopher

2008-12-01

30

Validated UPLC-MS/MS assay for the determination of synthetic phosphodiesterase type-5 inhibitors in postmortem blood samples.  

PubMed

The use of synthetic phosphodiesterase type 5 (PDE-5) inhibitors for the treatment of erectile dysfunction: sildenafil citrate (Viagra(®)), tadalafil (Cialis(®)) and vardenafil hydrochloride (Levitra(®)) has increased dramatically over the past 2 years. These substances are prescription drugs and must be used under medical supervision. However, they can easily be obtained over the internet from illegal sites, being a potential for a threat to public health. The development of an electrospray ionisation (ESI) ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) procedure for the simultaneous identification and quantification of three PDE5 inhibitors in blood samples was desired. Samples were prepared using Oasis(®) HLB solid-phase cartridges (3 cc, 60 mg) and chromatographic separation was achieved on an Acquity UPLC(®) HSS T3 (100 × 2.1 mm i.d., 1.8 ?m particles) column with a gradient mobile phase of 0.1% formic acid and acetonitrile at a 0.5 mL/min flow rate. Quantification was achieved by multiple reaction monitoring (MRM) of two transitions per compound: m/z 475.1 > 58 e m/z 475.1 > 311.1 for sildenafil; m/z 389.9 > 267.9 e m/z 389.9 > 134.8 for tadalafil and m/z 489 > 71.9 e m/z 489 > 150.9 for vardenafil. Zolpidem-d6 (m/z 314.5 > 235.3) was used as the internal standard. Calibration curves were linear over the concentration range of 5-1000 ng/mL, with a coefficient of determination better than 0.997. The lower limits of detection and quantification for these substances were ? 3 ng/mL and ? 8 ng/mL, respectively. The method showed a satisfactory sensitivity, precision, accuracy, recovery and selectivity. A rapid, selective and sensitive UPLC-MS/MS method using solid-phase extraction was developed for the simultaneous determination and quantification of sildenafil, vardenafil and tadalafil in blood samples. PMID:23910856

Proença, Paula; Mustra, Carla; Marcos, Mariana; Franco, João Miguel; Corte-Real, Francisco; Vieira, Duarte Nuno

2013-08-01

31

Analysis of Para Red and Sudan Dyes in Egg Yolk by UPLC–MS–MS  

Microsoft Academic Search

Matrix solid-phase dispersion (MSPD) with alumina N as adsorbent has been used for extraction of para red, Sudan 1, Sudan\\u000a 2, Sudan 3, and Sudan 4 dyes from egg yolk. The extracts were analyzed by ultra-performance liquid chromatography–tandem mass\\u000a spectrometry (UPLC–MS–MS). Mean recovery for the five dyes ranged from 63.2 to 98.6%, with CV 0.55–10.00%. One sample was\\u000a confirmed to

Xiaolin Hou; Yonggang Li; Shoujun Cao; Zhongwen Zhang; Yongnin Wu

2010-01-01

32

UPLC-MS/MS method for determination of avicularin in rat plasma and its application to a pharmacokinetic study.  

PubMed

A rapid, sensitive and selective ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of avicularin in rat plasma. Sample preparation was accomplished through a simple one-step deproteinization procedure with 0.2mL of acetonitrile-methanol (9:1, v/v) to a 0.1mL plasma sample. Plasma samples were separated by UPLC on an Acquity UPLC BEH C18 column using a mobile phase consisting of acetonitrile-0.1% formic acid in water with gradient elution. The total run time was 1.60min and the elution of avicularin was at 1.20min. The detection was performed on a triple quadrupole tandem mass spectrometer in the multiple reaction-monitoring (MRM) mode using the respective transitions m/z 434.1?301.3 for avicularin and m/z 237.2?194.3 for carbamazepine (IS), respectively. The calibration curve was linear over the range of 10-3000ng/mL with a lower limit of quantitation (LLOQ) of 10ng/mL. Mean recovery of avicularin in plasma was in the range of 84.2-89.5%. Intra-day and inter-day precision were both <12%. This method was successfully applied in pharmacokinetic study after intravenous administration of 5.0mg/kg avicularin in rats. PMID:25010713

Zhang, Wei-Min; Li, Rui-Fang; Sun, Ming; Hu, Da-Ming; Qiu, Jian-Fei; Yan, Yun-Hao

2014-08-15

33

Monitoring sea lamprey pheromones and their degradation using rapid stream-side extraction coupled with UPLC-MS/MS  

USGS Publications Warehouse

Pheromones guide adult sea lamprey (Petromyzon marinus) to suitable spawning streams and mates, and therefore, when quantified, can be used to assess population size and guide management. Here, we present an efficient sample preparation method where 100 mL of river water was spiked with deuterated pheromone as an internal standard and underwent rapid field-based SPE and elution in the field. The combination of field extraction with laboratory UPLC-MS/MS reduced the sample consumption from 1 to 0.1 L, decreased the sample process time from more than 1 h to 10 min, and increased the precision and accuracy. The sensitivity was improved more than one order of magnitude compared with the previous method. The influences of experimental conditions were assessed to optimize the separation and peak shapes. The analytical method has been validated by studies of stability, selectivity, precision, and linearity and by the determination of the limits of detection and quantification. The method was used to quantify pheromone concentration from five streams tributary to Lake Ontario and to estimate that the environmental half-life of 3kPZS is about 26 h.

Wang, Huiyong Wang; Johnson, Nicholas; Bernardy, Jeffrey; Hubert, Terry; Li, Weiming

2013-01-01

34

Simultaneous extraction and screening of diuretics, beta-blockers, selected stimulants and steroids in human urine by HPLC-MS/MS and UPLC-MS/MS.  

PubMed

Described herein are two general screening procedures for the simultaneous determination of 49 exogenous compounds (21 diuretics, 19 beta-blockers, eight stimulants and two steroidal drugs) in human urine by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Urine samples were extracted using a simple and robust solid phase extraction (SPE) method. Samples were injected onto reversed phase HPLC and UPLC columns connected to tandem mass spectrometers capable of scan-to-scan polarity switching. The methods were validated according to the ISO 17025 international standard for the validation of a qualitative method. Sixty urine samples submitted for routine analysis were tested using both methods, the results of which correlated with results obtained from previously validated procedures. Both methods proved to be useful for routine urine analysis; most notably, the use of UPLC-MS/MS demonstrated that samples can be reliably screened with significantly reduced analysis times. PMID:19837636

Murray, Gordon J; Danaceau, Jonathan P

2009-11-15

35

Metabolomic Analysis of Diet-Induced Type 2 Diabetes Using UPLC/MS Integrated with Pattern Recognition Approach  

PubMed Central

Metabolomics represents an emerging discipline concerned with comprehensive assessment of small molecule endogenous metabolites in biological systems and provides a powerful approach insight into the mechanisms of diseases. Type 2 diabetes (T2D), called the burden of the 21st century, is growing with an epidemic rate. However, its precise molecular mechanism has not been comprehensively explored. In this study, we applied urinary metabolomics based on the UPLC/MS integrated with pattern recognition approaches to discover differentiating metabolites, to characterize and explore metabolic pathway disruption in an experimental model for high-fat-diet induced T2D. Six differentiating urinary metabolites were found in the negative mode, and two (2-(4-hydroxy-3-methoxy-phenyl) acetaldehyde sulfate, 2-phenylethanol glucuronide) of which were identified involving the key metabolic pathways linked to pentose and glucuronate interconversions, starch, sucrose metabolism and tyrosine metabolism. Our study provides new insight into pathophysiologic mechanisms and may enhance the understanding of T2D pathogenesis.

Sun, Hui; Zhang, Shuxiang; Zhang, Aihua; Yan, Guangli; Wu, Xiuhong; Han, Ying; Wang, Xijun

2014-01-01

36

Free amino acid profiling in the giant puffball mushroom (Calvatia gigantea) using UPLC-MS/MS.  

PubMed

Wild edible and medicinal mushroom, Calvatia gigantea, was quantitatively analyzed for the determination of its free amino acids using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The concentrations of total free amino acids, essential and non-essential amino acids were 199.65mg/100g, 113.69mg/100g, and 85.96mg/100g in C. gigantea, respectively. This study showed that C. gigantea, so called a giant puffball mushroom, has free amino acids content. The essential amino acids: tryptophan, isoleucine, valine, phenylalanine, leucine, threonine, lysine, histidine, methionine, and the non-essential amino acids: tyrosine, 4-hyrdroxy proline, arginine, proline, glycine, serine, alanine, glutamine, glutamic acid, aspargine, aspartic acid were detected. PMID:24731318

K?vrak, Ibrahim; K?vrak, Seyda; Harmandar, Mansur

2014-09-01

37

UPLC-MS/MS method for bioequivalence study of oral drugs of meldonium.  

PubMed

A rapid and simple method based on ultra-performance liquid chromatography on a hydrophilic interaction chromatography column with tandem mass-selective detection (UPLC-MS/MS) to determine meldonium in human plasma was developed. The calibration curve acquired in the range of 10-6000 ng/mL had quadratic form. Method validation proved the conformity of its properties (selectivity, matrix effect, lower limit of quantification, accuracy, precision and recovery) with the established requirements. The stability tests necessary for bioanalytical studies were performed. For the first time, the method was successfully applied to the bioequivalence studies of generic and brand name oral drugs of meldonium in capsules. Based on data from 24 volunteers, it was determined that the mean pharmacokinetic curves of the drugs are characterized by a double peak profile. PMID:21915891

Pidpruzhnykov, Yuriy V; Sabko, Valerii E; Iurchenko, Volodymyr V; Zupanets, Igor A

2012-05-01

38

Simultaneous determination of bioactive components of Radix Angelicae Sinensis-Radix Paeoniae Alba herb couple in rat plasma and tissues by UPLC-MS/MS and its application to pharmacokinetics and tissue distribution.  

PubMed

A highly sensitive and rapid ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been developed and validated for simultaneous quantification of seven components in rat plasma and five components in rat tissues after oral administration of the extracts of different combination Radix Angelicae Sinensis-Radix Paeoniae Alba herb couple and has been applied to compare the different pharmacokinetics and tissue distribution properties of these bioactive components. The extracts of Radix Angelicae Sinensis (RAS), Radix Paeoniae Alba (RPA) and Radix Angelicae Sinensis-Radix Paeoniae Alba herb couple (RRHC) were orally administrated to rats, respectively. The concentrations of ferulic acid, caffeic acid, vanillic acid, ligustilide, paeoniflorin, albiflorin and oxypaeoniflorin in rat plasma and the concentrations of ferulic acid, vanillic acid, paeoniflorin, albiflorin and oxypaeoniflorin in tissues were determined by UPLC-MS/MS. The plasma samples were pretreated by protein precipitation with methanol and the tissue samples were homogenated with water and pretreated by protein precipitation with methanol. Chromatographic separation was performed on a C18 column using 0.1% formic acid-acetonitrile as mobile phase for gradient elution. A triple quadrupole (TQ) tandem mass spectrometry equipped with an electrospray ionization source was used as detector operating both in positive and negative ionization mode and operated by multiple-reaction monitoring (MRM) scanning. Noncompartmental pharmacokinetic parameters were calculated by DAS 2.0 program. The differences between each group were compared by SPSS 16.0 with Independent-Samples T-test. The pharmacokinetic parameters (such as Cmax, Tmax, T1/2, AUC0-T, MRT0-T, Vz/F or CLz/F) of all the detected components between the single herb (RAS or RPA) and herb pair (RRHP) showed significant differences (P<0.05). It indicated that the compatibility of RAS and RPA could alter the pharmacokinetics features of each component. Tissue distribution results showed that ferulic acid, vanillic acid, paeoniflorin, albiflorin and oxypaeoniflorin mostly distributed in liver and kidney both in herb couple and single herb distributed most in liver and kidney. Compared with single herb, RRHC could increase or decrease the concentrations of five components at different time points compared with the sing herb. The results indicated the method was successfully applied to the comparative study on pharmacokinetics and tissue distribution of different combination of RRHC in rats. The compatibility of two Chinese herbs could alter the pharmacokinetics and tissue distribution properties of major bio-active components in the single herb. The results might be helpful for further investigation of compatibility mechanism of RRHC. PMID:24927419

Luo, Niancui; Li, Zhenhao; Qian, Dawei; Qian, Yefei; Guo, Jianming; Duan, Jin-Ao; Zhu, Min

2014-07-15

39

Photodegradation assessment of ciprofloxacin, moxifloxacin, norfloxacin and ofloxacin in the presence of excipients from tablets by UPLC-MS/MS and DSC  

PubMed Central

Background Ciprofloxacin (CIP), moxifloxacin (MOX), norfloxacin (NOR) and ofloxacin (OFL), are the antibacterial synthetic drugs, belonging to the fluoroquinolones group. Fluoroquinolones are compounds susceptible to photodegradation process, which may lead to reduction of their antibacterial activity and to induce phototoxicity as a side effect. This paper describes a simple, sensitive UPLC-MS/MS method for the determination of CIP, MOX, NOR and OFL in the presence of photodegradation products. Results Chromatographic separations were carried out using the Acquity UPLC BEH C18 column; (2.1?×?100 mm, 1.7 ?m particle size). The column was maintained at 40°C, and the following gradient was used: 0 min, 95% of eluent A and 5% of eluent B; 10 min, 0% of eluent A and 100% of eluent B, at a flow rate of 0.3 mL min-1. Eluent A: 0.1% (v/v) formic acid in water; eluent B: 0.1% (v/v) formic acid in acetonitrile. The method was validated and all the validation parameters were in the ranges acceptable by the guidelines for analytical method validation. The photodegradation of examined fluoroquinolones in solid phase in the presence of excipients followed kinetic of the first order reaction and depended upon the type of analyzed drugs and coexisting substances. Photodegradation process of analyzed drugs was confirmed by differential scanning calorimetry. In addition, the identification of degradation products was carried out by mass spectrometry. Conclusion The developed UPLC-MS/MS method enables the determination of CIP, MOX, NOR and OFL in the presence of photodegradation products and identification of photodegradation products.

2013-01-01

40

Simultaneous determination of mequindox, quinocetone, and their major metabolites in chicken and pork by UPLC-MS/MS.  

PubMed

This report presents a UPLC-MS/MS method for determination of mequindox (MEQ), quinocetone (QCT) and their 11 metabolites in chicken and pork samples. Following extraction process with acetonitrile-ethyl acetate, acidulation, and re-extraction with ethyl acetate in turn, target analytes were further purified using C18 solid phase extraction (SPE) cartridges for UPLC-MS/MS analysis. Validation was processed with mean recoveries from 69.1% to 113.3% with intra-day relative standard deviation (RSD) <14.7%, inter-day RSD <19.2%, and limit of detection between 0.05 and 1.0 ?g/kg for each analytes. The verified method was successfully applied to the quantitative determination of commercial samples. This developed procedure will help to control food animal products with MEQ and QCT residues, and facilitate further pharmacokinetic and residue studies of similar quinoxaline-1,4-dioxide veterinary drugs. PMID:24799224

Li, Yanshen; Liu, Kaili; Beier, Ross C; Cao, Xingyuan; Shen, Jianzhong; Zhang, Suxia

2014-10-01

41

Identification and quantitation of new glutamic acid derivatives in soy sauce by UPLC/MS/MS.  

PubMed

Glutamic acid is an abundant amino acid that lends a characteristic umami taste to foods. In fermented foods, glutamic acid can be found as a free amino acid formed by proteolysis or as a non-proteolytic derivative formed by microorganisms. The aim of the present study was to identify different structures of glutamic acid derivatives in a typical fermented protein-based food product, soy sauce. An acidic fraction was prepared with anion-exchange solid-phase extraction (SPE) and analyzed by UPLC/MS/MS and UPLC/TOF-MS. ?-Glutamyl, ?-glutamyl, and pyroglutamyl dipeptides, as well as lactoyl amino acids, were identified in the acidic fraction of soy sauce. They were chemically synthesized for confirmation of their occurrence and quantified in the selected reaction monitoring (SRM) mode. Pyroglutamyl dipeptides accounted for 770?mg/kg of soy sauce, followed by lactoyl amino acids (135?mg/kg) and ?-glutamyl dipeptides (70?mg/kg). In addition, N-succinoylglutamic acid was identified for the first time in food as a minor compound in soy sauce (5?mg/kg). PMID:24130027

Frerot, Eric; Chen, Ting

2013-10-01

42

UPLC-MS/MS determination in blood of a mixed-drug fatal intoxication: a case report.  

PubMed

Trends in forensic toxicology show the introduction of rapid analytical methods for the simultaneous quantitative analysis of drugs. The authors present a fatal case involving a 32-year-old male, found dead in bed by his mother, with several blue, white and orange pills next to the body. Empty tablets were found in the trash bin and a suicide note was on the desk. He was diagnosed with bipolar disorder and had been under psychiatric treatment, having repeatedly demonstrated intent to commit suicide. A rapid method was developed to determine 55 different medicines and 32 benzodiazepines in blood by ultra-performance liquid chromatography (UPLC) coupled with tandem mass spectrometry (MS/MS) with electrospray ionization source in positive and negative ion mode. Chromatographic analysis was preceded by an optimized solid-phase extraction procedure using Oasis(®) HLB (3 cc, 60 mg) extraction columns. The extracted analytes were separated by UPLC (Waters) with a reversed-phase Acquity UPLC(®) HSS T3 (2.1×100 mm id, 1.8 ?m) column with acetonitrile and 0.1% formic acid in water as mobile phase, at 0.5 mL/min flow rate and a chromatographic run-time of 8 min. Analytes detection was achieved with a triple-quadrupole mass spectrometer in positive and negative electrospray ionization mode with multiple reaction monitoring (MRM). Two MRM transitions were monitored for each target-compound and one for each deuterated internal standards. Toxicological results showed high blood concentrations of antipsychotics (haloperidol, olanzapine and quetiapine), antidepressants (fluoxetine and paroxetine) and anxiolytics (bromazepam and lorazepam). Risperidone and other benzodiazepines were also present in therapeutic concentrations. Neither alcohol nor illicit drugs were present in the analyzed samples. The UPLC-MS-MS method showed to be appropriate for screening, identification and quantitation of antipsychotics, antidepressants, anxiolytics and antiepileptic drugs in blood after intake of therapeutic as well as toxic doses. The autopsy and toxicological results led the pathologist to rule that death was due to a mixed-drug intoxication. The manner of death was determined to be suicide. PMID:23159339

Proença, Paula; Franco, João Miguel; Mustra, Carla; Monteiro, Carla; Costa, Joana; Corte-Real, Francisco; Vieira, Duarte Nuno

2013-04-10

43

Drug screening in medical examiner casework by high-resolution mass spectrometry (UPLC-MSE-TOF).  

PubMed

Postmortem drug findings yield important analytical evidence in medical examiner casework, and chromatography coupled with nominal mass spectrometry (MS) serves as the predominant general unknown screening approach. We report screening by ultra performance liquid chromatography (UPLC) coupled with hybrid quadrupole time-of-flight mass spectrometer (MS(E)-TOF), with comparison to previously validated nominal mass UPLC-MS and UPLC-MS-MS methods. UPLC-MS(E)-TOF screening for over 950 toxicologically relevant drugs and metabolites was performed in a full-spectrum (m/z 50-1,000) mode using an MS(E) acquisition of both molecular and fragment ion data at low (6 eV) and ramped (10-40 eV) collision energies. Mass error averaged 1.27 ppm for a large panel of reference drugs and metabolites. The limit of detection by UPLC-MS(E)-TOF ranges from 0.5 to 100 ng/mL and compares closely with UPLC-MS-MS. The influence of column recovery and matrix effect on the limit of detection was demonstrated with ion suppression by matrix components correlating closely with early and late eluting reference analytes. Drug and metabolite findings by UPLC-MS(E)-TOF were compared with UPLC-MS and UPLC-MS-MS analyses of postmortem blood in 300 medical examiner cases. Positive findings by all methods totaled 1,528, with a detection rate of 57% by UPLC-MS, 72% by UPLC-MS-MS and 80% by combined UPLC-MS and UPLC-MS-MS screening. Compared with nominal mass screening methods, UPLC-MS(E)-TOF screening resulted in a 99% detection rate and, in addition, offered the potential for the detection of nontargeted analytes via high-resolution acquisition of molecular and fragment ion data. PMID:23999055

Rosano, Thomas G; Wood, Michelle; Ihenetu, Kenneth; Swift, Thomas A

2013-10-01

44

Identification of metabolites in human hepatic bile using 800 MHz 1H NMR spectroscopy, HPLC-NMR/MS and UPLC-MS.  

PubMed

The first application of high field NMR spectroscopy (800 MHz for (1)H observation) to human hepatic bile (as opposed to gall bladder bile) is reported. The bile sample used for detailed investigation was from a donor liver with mild fat infiltration, collected during organ retrieval prior to transplantation. In addition, to focus on the detection of bile acids in particular, a bile extract was analysed by 800 MHz (1)H NMR spectroscopy, HPLC-NMR/MS and UPLC-MS. In the whole bile sample, 40 compounds have been assigned with the aid of two-dimensional (1)H-(1)H TOCSY and (1)H-(13)C HSQC spectra. These include phosphatidylcholine, 14 amino acids, 10 organic acids, 4 carbohydrates and polyols (glucose, glucuronate, glycerol and myo-inositol), choline, phosphocholine, betaine, trimethylamine-N-oxide and other small molecules. An initial NMR-based assessment of the concentration range of some key metabolites has been made. Some observed chemical shifts differ from expected database values, probably due to a difference in bulk diamagnetic susceptibility. The NMR spectra of the whole extract gave identification of the major bile acids (cholic, deoxycholic and chenodeoxycholic), but the glycine and taurine conjugates of a given bile acid could not be distinguished. However, this was achieved by HPLC-NMR/MS, which enabled the separation and identification of ten conjugated bile acids with relative abundances varying from approximately 0.1% (taurolithocholic acid) to 34.0% (glycocholic acid), of which, only the five most abundant acids could be detected by NMR, including the isomers glycodeoxycholic acid and glycochenodeoxycholic acid, which are difficult to distinguish by conventional LC-MS analysis. In a separate experiment, the use of UPLC-MS allowed the detection and identification of 13 bile acids. This work has shown the complementary potential of NMR spectroscopy, MS and hyphenated NMR/MS for elucidating the complex metabolic profile of human hepatic bile. This will be useful baseline information in ongoing studies of liver excretory function and organ transplantation. PMID:19156264

Duarte, Iola F; Legido-Quigley, Cristina; Parker, David A; Swann, Jonathan R; Spraul, Manfred; Braumann, Ulrich; Gil, Ana M; Holmes, Elaine; Nicholson, Jeremy K; Murphy, Gerard M; Vilca-Melendez, Hector; Heaton, Nigel; Lindon, John C

2009-02-01

45

[Metabonomic study on protective effect of ethanol extracts of drynariae rhizoma on osteoporosis in rats urine by using UPLC-MS/MS].  

PubMed

This paper was designed to study metabonomic characters of the osteoporosis induced by high dose of hydrocortisone and the protective effects of Drynariae Rhizoma, which can replenish the kidney and strengthen the bones. A urinary metabonomics method based on ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS/MS) was developed. Clear separation of healthy control group, model group and treatment group was achieved by using the principal components analysis (PCA) and 9 significantly changed metabolites were identified as potential biomarkers of osteoporosis. Compared with the health control group, the model group rats showed lower levels of creatinine, citric acid, azelaic acid, hippurate, tryptophan and indoxyl sulfate together with higher levels of phenylalanine, cresol sulfate and phenaceturic acid. These changes in urinary metabolites suggest that the disorders of amino acid metabolism, energy metabolism, gut microflora and anti-oxidative damage are related to osteoporosis induced by high dose of hydrocortisone and the potential effect of Drynariae Rhizoma on all the four metabolic pathways. PMID:22693913

Zhang, Shangshang; Liu, Xinyu; Zheng, Shuning; Jiang, Minyan; Xin, Changying; Lu, Xiumei; Li, Famei; Xiong, Zhili

2012-03-01

46

Quantitative Determination of Levonorgestrel in Fish Plasma using UPLC-MS/MS  

EPA Science Inventory

In this study, a sensitive high-performance liquid chromatography electrospray tandem mass spectrometric method was developed for the determination of levonorgestrel in fish plasma using levonorgestrel-d6 as an internal standard (IS). In the laboratory, the fish cunner, (Tautogol...

47

A novel UPLC/MS/MS method for rapid determination of metapristone in rat plasma, a new cancer metastasis chemopreventive agent derived from mifepristone (RU486).  

PubMed

Mifepristone (RU486) is a chemical abortifacient used by hundreds of millions of women world-wide. It has recently been used in clinical trials for psychotic depression and cancer chemotherapy. Metapristone is the most predominant biological active metabolite of mifepristone, and being developed as a novel cancer metastasis chemopreventive agent based on its unique pharmacological properties. In this study, a novel rapid and sensitive method using UPLC/MS/MS was developed and validated for quantitative analysis of metapristone in plasma, which used less plasma volume and was demonstrated to be more simple and low-cost than the published methods. Metapristone in plasma was recovered by liquid-liquid extraction using 1 mL of ethyl acetate and chromatographic separation was carried on a C?? column at 35 °C, with a gradient mobile phase consisting of methanol and water containing 0.1% (v/v) formic acid at a flow rate of 0.3 mL/min. The mass spectrometric detection was carried out using a triple-quadrupole system via positive electrospray ionization. Multiple reaction monitoring was used for quantitation of m/z transitions from 416.3 to 119.9 for metapristone and from 313.1 to 109 for levonorgestrel (internal standard). Good linearity (r²> 0.9926) was achieved over a concentration range from 7.1 to 2840 ng/mL with a lower limit of quantification of 7.1 ng/mL for metapristone. The intra- and inter-day variations of the assay were 2.4-10.0% relative standard deviation with an accuracy of -5.6 to 8.6% relative error. This newly developed method was successfully applied to a pharmacokinetic study that revealed, for the first time, that there was a significant difference in pharmacokinetic profile between genders. PMID:24682015

Chen, Jian-Zhong; Wang, Ji-Chuang; Gao, Yu; Zeng, Rong-Jie; Jiang, Zhou; Zhu, Ye-Wei; Shao, Jing-Wei; Jia, Lee

2014-07-01

48

Evaluation of the migration of 15 photo-initiators from cardboard packaging into Tenax(®) using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).  

PubMed

Photo-initiators are widely used to cure ink on packaging materials used in food applications such as plastic films or cartonboards. In migration studies, food simulants are very often used to simulate food, like Tenax(®), which is the simulant for dry foodstuffs. In this paper a fast and reliable confirmation method for the determination of the following photo-initiators in Tenax(®) is described: benzophenone (BP), 4,4'-bis(diethylamino)benzophenone (DEAB), 2-chloro-9H-thioxanthen-9-one (CTX), 1-chloro-4-propoxy-9H-thioxanthen-9-one (CPTX), 2,4-diethyl-9H-thioxanthen-9-one (DETX), 2,2-dimethoxy-2-phenyl acetophenone (DMPA), 4-(dimethylamino)benzophenone (DMBP), 2-ethylanthraquinone (EA), ethyl-4-dimethylaminobenzoate (EDMAB), 1-hydroxylcyclohexyl phenyl ketone (HCPK), 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (HMMP), 2-isopropyl-9H-thioxanthen-9-one (ITX), 4-methylbenzophenone (MBP), Michler's ketone (MK), and 4-phenylbenzophenone (PBZ). After the migration study was completed, the simulant Tenax(®) was extracted using acetonitrile, followed by analysis on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Quantification was carried out using benzophenone-d10 (BP-d10) as internal standard. The presented method is validated in terms of matrix effect, specificity, linearity, recovery, precision and sensitivity, showing the method can detect all photo-initiators at very low concentrations (LOD < 0.125 µg g(-1) for all substances). Finally, the procedure was applied to real samples, proving the capabilities of the presented method. PMID:24447245

Van Den Houwe, K; van de Velde, S; Evrard, C; Van Hoeck, E; Van Loco, J; Bolle, F

2014-04-01

49

Simultaneous determination of phenolic acids by UPLC-MS/MS in rat plasma and its application in pharmacokinetic study after oral administration of Flos Lonicerae preparations.  

PubMed

The current study aims to investigate the pharmacokinetic study of five phenolic acids (neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, 3,5-dicaffeoylquinic acid and 3,4-dicaffeoylquinic acid) following oral administration of Flos Lonicerae preparations in rats. A rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to simultaneously determine the five phenolic acids in rat plasma. After mixing with the internal standard (IS) tinidazole, plasma samples were pretreated by liquid-liquid extraction with ethyl acetate/n-hexane (9:1, v/v). The separation was performed on an Acquity UPLC BEH C18 column (100mm×2.1mm, 1.7?m) at a flow rate of 0.4mlmin(-1), and acetonitrile/methanol (4:1, v/v)-0.4% formic acid was used as mobile phase. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) via electrospray ionization (ESI) source with positive ionization mode. All calibration curves had good linearity (r>0.991) over the concentration ranges of 0.74-378ngml(-1) for neochlorogenic acid, 0.50-1030ngml(-1) for chlorogenic acid, 1.9-250ngml(-1) for cryptochlorogenic acid, 0.74-380ngml(-1) for 3,5-dicaffeoylquinic acid, and 5.1-328ngml(-1) for 3,4-dicaffeoylquinic acid. The intra-and inter-day precision were within 15% and the accuracy ranged from 86.2% to 114.1%. PMID:24004636

Zhou, Wei; Liu, Shijia; Ju, Wenzheng; Shan, Jinjun; Meng, Minxin; Cai, Baochang; Di, Liuqing

2013-12-01

50

Rapid quantification of 14 saponins of Maesa lanceolata by UPLC-MS/MS.  

PubMed

Saponins are high molecular weight glycosides which are known for their broad range of biological activities. In case of Maesa lanceolata, a tree growing in African countries, the maesasaponins showed virucidal, haemolytic, molluscicidal and anti-angiogenic activity. Since the different activities are dependent on the structure of the saponins, a method was developed and validated for the analysis of the individual saponins in this plant. Since the saponins were only present in small amounts, it was necessary to develop a very sensitive analytical method. For the fast and sensitive analysis of the extracted and purified plant samples ultra-performance liquid chromatography was coupled to a triple quadrupole mass spectrometer for MS/MS detection. A method in positive ESI mode, using sodium acetate in the mobile phase, was developed. The sodium adduct ion was selected as the precursor ion since it provided better sensitivity and a better, more stable fragmentation compared to the deprotonated and protonated ions. The intensity of the signal obtained by fragmentation of the sodium adducts of the saponins, was optimized by the addition of different concentrations of sodium acetate to the mobile phase. Reference standards were not available for all 14 saponins. Therefore, a relative MS/UV response was calculated allowing the estimation of the saponins in real samples. alpha-Hederin was used as external standard. The method was linear over the investigated concentration range with a good correlation coefficient (>0.99). The intra- and inter-day precisions were below 15% for most maesasaponins with the exception of maesasaponin II, which showed a precision within 20%. The recoveries of the spiked pure compounds maesasaponin IV.1 and VII.1 were 96.6% and 85.5%, respectively. The validated method can be applied in the investigation of the content of 14 saponins in transgenic and non-transgenic plant material of M. lanceolata. PMID:20441893

Foubert, K; Cuyckens, F; Vleeschouwer, K; Theunis, M; Vlietinck, A; Pieters, L; Apers, S

2010-06-15

51

Comparison of sample preparation methods, validation of an UPLC-MS/MS procedure for the quantification of tetrodotoxin present in marine gastropods and analysis of pufferfish.  

PubMed

Tetrodotoxin (TTX) is one of the most potent marine neurotoxins reported. The global distribution of this toxin is spreading with the European Atlantic coastline now being affected. Climate change and increasing pollution have been suggested as underlying causes for this. In the present study, two different sample preparation techniques were used to extract TTX from Trumpet shells and pufferfish samples. Both extraction procedures (accelerated solvent extraction (ASE) and a simple solvent extraction) were shown to provide good recoveries (80-92%). A UPLC-MS/MS method was developed for the analysis of TTX and validated following the guidelines contained in the Commission Decision 2002/657/EC for chemical contaminant analysis. The performance of this procedure was demonstrated to be fit for purpose. This study is the first report on the use of ASE as a mean for TTX extraction, the use of UPLC-MS/MS for TTX analysis, and the validation of this method for TTX in gastropods. PMID:23194566

Nzoughet, Judith Kouassi; Campbell, Katrina; Barnes, Paul; Cooper, Kevin M; Chevallier, Olivier P; Elliott, Christopher T

2013-02-15

52

Analysis of lipid peroxidation biomarkers in extremely low gestational age neonate urines by UPLC-MS/MS.  

PubMed

Extremely low gestational age neonates (ELGAN) frequently require the use of oxygen supply in the delivery room leading to systemic inflammation and oxidative stress that are responsible for increased morbidity and mortality. The objective of this study was to establish reference ranges of a set of representative isoprostanes and prostaglandins, which are stable biomarkers of lipid peroxidation often correlated with oxidative stress-related disorders. First, a quantitative ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated. The proposed analytical method was tailored for its application in the field of neonatology, enabling multi-analyte detection in non-invasive, small-volume urine samples. Then, the lipid peroxidation product concentrations in a total of 536 urine samples collected within the framework of two clinical trials including extremely low gestational age neonates (ELGAN) were analyzed. The access to a substantially large number of samples from this very vulnerable population provided the chance to establish reference ranges of the studied biomarkers. Up to the present, and for this population, this is the biggest reference data set reported in literature. Results obtained should assist researchers and pediatricians in interpreting test results in future studies involving isoprostanes and prostaglandins, and could help assessing morbidities and evaluate effectiveness of treatment strategies (e.g., different resuscitation conditions) in the neonatal field. PMID:24817352

Kuligowski, Julia; Escobar, Javier; Quintás, Guillermo; Lliso, Isabel; Torres-Cuevas, Isabel; Nuñez, Antonio; Cubells, Elena; Rook, Denise; van Goudoever, Johannes B; Vento, Máximo

2014-07-01

53

Determination of rhynchophylline and hirsutine in rat plasma by UPLC-MS/MS after oral administration of Uncaria rhynchophylla extract.  

PubMed

An ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to concurrently determine rhynchophylline and hirsutine in rat plasma. The sample preparation of rat plasma was achieved by alkalization and liquid-liquid extraction. The mass transition of precursor ion???product ion pairs were monitored at m/z 385.2???160.0 for rhynchophylline, m/z 369.3???144.0 for hirsutine and m/z 414.0???220.0 for noscapine (internal standard). This method revealed linear relationships from 2.5 to 50?ng/mL (r(2) ?>?0.997) for rhynchophylline and from 2.5 to 50?ng/mL (r(2) ?>?0.998) for hirsutine. The limit of quantification values for rhynchophylline and hirsutine in rat plasma were both 2.5?ng/mL. Intra-day and inter-day precisions were within 10.6% and 12.5%, respectively, for rhynchophylline and hirsutine, and the accuracy (bias) was <10%. Liquid-liquid extraction of rat plasma samples resulted in insignificant matrix effect, and the extraction recoveries were >83.6% for rhynchophylline, 73.4% for hirsutine and 90.7% for the internal standard. This method was applied successfully to a pharmacokinetic study of rhynchophylline and hirsutine in rats after oral administration. PMID:24122787

Wu, Yu-Tse; Lin, Lie-Chwen; Tsai, Tung-Hu

2014-03-01

54

Determination of Pseudoginsengenin DQ in rat plasma by UPLC-MS/MS and application of the method in a pharmacokinetic study.  

PubMed

Pseudoginsengenin DQ (pseudoginsengenin of diol derivatives quest, PDQ), the product of the oxidative cyclization of protopanaxadiol, exhibits a significant pharmacological effect as an antiarrhythmic agent. A sensitive and rapid analytical method based on ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) was initially developed for the detection of PDQ in rat plasma. Pre-treatment of the sample obtained from the plasma involved a single protein precipitation step, using methanol. PDQ and an internal standard (IS), physcion, were separated on a Waters ACQUITY UPLC BEH C18 analytical column (50mm×2.1mm, 1.7?m) using acetonitrile-0.1% formic acid in water (70:30, v/v) as the mobile phase, at a flow rate of 0.3mL/min. Chromatography of the PDQ and IS was performed within 3min. Detection was performed through positive ion electrospray ionization (ESI(+)) in multiple reaction-monitoring (MRM) mode. The assay was linear over the concentration range of 5-1000ng/mL (r>0.9980). The limit of detection (LOD) and the lower limit of quantification (LLOQ) were 0.5ng/mL and 5.0ng/mL, respectively. The intra- and inter-day deviations (expressed as relative standard deviation, RSD) were ?9.5% and ?1.7%, respectively, and the accuracy (expressed as relative error, RE) was in the range of -1.1 to 2.7%. The recoveries of PDQ and IS were 95.2% and 100.7%, respectively, and the matrix effects were satisfactory in all of the biological matrices examined. This fully validated method was successfully applied to the pharmacokinetic study of rats after a single initial intragastric administration of 15mg/kg PDQ. The main pharmacokinetic parameters: Tmax (the time to peak), Cmax (the concentration to peak), and t1/2 (the biological half time) were 4.0±0.0h, 3265.12±700.26ng/mL, 5.97±0.43h, respectively. PMID:23845389

Gao, Hongmei; Li, Zhuo; Li, Pingya; Lin, Meiyu; Han, Liu; Wang, Fang; Liu, Jinping

2013-08-15

55

Two rapid ultra performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) methods with common sample pretreatment for therapeutic drug monitoring of immunosuppressants compared to immunoassay.  

PubMed

Therapeutic drug monitoring of immunosuppressive agents is a critical and essential part of patient therapy after organ transplantation. We have developed high-throughput, robust, and rapid liquid chromatography-tandem mass spectrometry (UPLC/MS/MS) methods with common pretreatment procedures for simultaneous quantification of four immunosuppressive agents (everolimus, sirolimus, tacrolimus, and cyclosporin A) in whole blood and one immunosuppressant (mycophenolic acid) in plasma. The new approach used in this work is based on improved sample preparation procedures allowing the analysis of five immunosuppressive drugs. Whole blood was prepared by transferring 100?L of blood into a 1.5-mL silanized conical test tube. Zinc sulfate solution (150?L), containing deuterated internal standards, was added to perform hemolysis. The samples were vortexing for 10s, followed by the addition of 250?L acetonitrile, containing internal standard for cyclosporin A, to precipitate proteins. The mixture was vortexed for 1min and centrifuged for 2min at 14,000rpm. The whole supernatant was transferred to a vial. To prepare blood plasma, the hemolysis step involving the addition of zinc sulfate was omitted and, instead of acetonitrile, methanol was used as the solvent for the internal standard (mycophenolic acid-d3). The volumes of chemicals used in this procedure were the same as those used in the procedure for immunosuppressants in whole blood. The basic validation parameters for the analytical methods were limits of detection (0.5ng/mL for everolimus, sirolimus and tacrolimus, 25ng/mL for cyclosporin A and 100ng/mL for mycophenolic acid), precision (<15%), recovery (>84%), repeatability and reproducibility. Possible mutual ion suppression was eliminated in the presence of internal standards. The method developed for the quantitation of immunosuppressants in whole blood was used to analyze 276 patient samples containing tacrolimus and 55 samples containing cyclosporin A. The results from LC/MS/MS were compared to those obtained from immunoassays of the same samples. Immunoassays significantly overestimated the concentrations of immunosuppressants. PMID:23584041

Tszyrsznic, Wlodzimierz; Borowiec, Agnieszka; Pawlowska, Emilia; Jazwiec, Radoslaw; Zochowska, Dorota; Bartlomiejczyk, Irena; Zegarska, Jolanta; Paczek, Leszek; Dadlez, Michal

2013-06-01

56

Pharmacokinetic properties of isorhamnetin, kaempferol and quercetin after oral gavage of total flavones of Hippophae rhamnoides L. in rats using a UPLC-MS method.  

PubMed

An ultra performance liquid chromatography-mass spectrometric (UPLC-MS) method was developed to investigate the pharmacokinetic properties of isorhamnetin, kaempferol and quercetin from a total flavone extract of Hippophae rhamnoides L. (TFH) after single dose oral administration. Rat plasma samples were pretreated using liquid-liquid extraction, and chromatographic separation was performed on a C(18) column using a linear gradient of methanol and formic acid (0.1%). The pharmacokinetic parameters of isorhamnetin, kaempferol and quercetin from TFH in rats were quantitatively determined by UPLC with photodiode array detection (PDA). The qualitative detection of the three flavones was accomplished by selected ion monitoring in negative ion mode ESI-MS. Results of the pharmacokinetic study indicate that the three flavones in TFH were absorbed by passive diffusion in rats, and no "double-peak" phenomenon was observed in C-t curves of the three flavones from TFH except for quercetin. Results of this study indicate that the pharmacokinetic behaviors of isorhamnetin, kaempferol and quercetin when administered together in a complex herbal extract might be different than the individual behaviors of the same compounds administered in their pure forms. Results of this study also demonstrate that UPLC-MS is a rapid and practical method to determine the pharmacokinetic parameters of flavones present in an herbal extract. PMID:22056665

Li, Guowen; Zeng, Xiaoli; Xie, Yan; Cai, Zhenzhen; Moore, Jeffrey C; Yuan, Xiurong; Cheng, Zhihong; Ji, Guang

2012-01-01

57

Effects of borneol on the pharmacokinetics of geniposide in cortex, hippocampus, hypothalamus and striatum of conscious rat by simultaneous brain microdialysis coupled with UPLC-MS.  

PubMed

It has been verified that borneol could promote the accumulation of other drugs in the whole brain. In this study, a microdialysis sampling system coupled with UPLC-MS was developed to evaluate the delivery of geniposide to four brain regions (cortex, hippocampus, hypothalamus and striatum) of conscious rats in the absence/presence of borneol: rats were administrated with geniposide alone (300mg/kg, iv) or administrated with both geniposide and borneol (0.2g/kg, ig). The dialysate collected from specific brain area was analyzed by a UPLC-MS system: separated on a BEH C18 column (50mm×2.1mm id, 1.7?m) within 1.5min, and detected in positive ion electrospray mode. The calibration curve was in good linearity over the concentration range of 0.009-90?g/mL. The inter- and intra-day accuracies were within ±10%, and the precisions were within 9.13%. The established method was applied to study the brain pharmacokinetics of geniposide and the results demonstrated that borneol markedly facilitated the delivery of geniposide to hippocampus and hypothalamus, but slightly hampered its delivery in cortex. PMID:23417086

Yu, Bin; Ruan, Ming; Cui, Xiao-bing; Guo, Jian-Ming; Xu, Li; Dong, Xiao-Ping

2013-04-15

58

Simultaneous determination of paeoniflorin, albiflorin, ferulic acid, tetrahydropalmatine, protopine, typhaneoside, senkyunolide I in Beagle dogs plasma by UPLC-MS/MS and its application to a pharmacokinetic study after Oral Administration of Shaofu Zhuyu Decoction.  

PubMed

In this present study, a sensitive and rapid UPLC-MS/MS method was developed for simultaneous quantification of paeoniflorin, albiflorin, ferulic acid, tetrahydropalmatine, protopine, typhaneoside and senkyunolide I in Beagle dog plasma after oral administration of the Shao-Fu-Zhu-Yu Decoction. Chloramphenicol and clarithromycin were used as internal standards. Plasma samples were processed by protein precipitation with methanol. The separation was performed on an Acquity BEH C18 column (100mm×2.1mm, 1.7?m) at a flow-rate of 0.4mL/min, using 0.1% formic acid-acetonitrile as mobile phase. Method validation was performed as per Food and Drug Administration guidelines and the results met the acceptance criteria. After validation, this method was successfully applied to a pharmacokinetic study. The results showed that the apparent plasma clearance of paeoniflorin, albiflorin, typhaneoside and senkyunolide I were significantly higher than others. Double peak was observed in plasma concentration curves of tetrahydropalmatine, the ferulic acid had a good absorption in Beagle dog plasma, and senkyunolide I was detected in plasma from the first blood sampling time (15min) and rapidly reached Tmax. The compound of typhaneoside has a low bioavailability according to the results. PMID:24907546

Huang, Xiaochen; Su, Shulan; Cui, Wenxia; Liu, Pei; Duan, Jin-Ao; Guo, Jianming; Li, Zhenhao; Shang, Erxin; Qian, Dawei; Huang, Zhijun

2014-07-01

59

[ureido-(15)N]Citrulline UPLC-MS/MS nitric oxide synthase (NOS) activity assay: Development, validation, and applications to assess NOS uncoupling and human platelets NOS activity.  

PubMed

In healthy human subjects, less than 0.2% of l-arginine is converted to l-citrulline and nitric oxide (NO) by NO synthases (NOS), a metabolic pathway present in all cell types. Assessment of NOS activity in vitro and in vivo by measuring l-citrulline or NO is difficult. l-citrulline is formed from l-arginine to a much higher extent by other pathways including the urea cycle. Furthermore, NO is a very short-lived gaseous molecule and is oxidized to nitrite and nitrate which are ubiquitous. In fact, nitrite and nitrate are also derived from food and air and are major laboratory contaminants. Further, NOS (in the uncoupled state) are also able to produce superoxide in addition and/or instead of l-citrulline and NO. The difficulties of NOS assays based on l-citrulline and NO measurement can only in part be overcome by sophisticated techniques including use of radio-labeled ((3)H or (14)C) and stable-isotope labeled ((15)N2 at the guanidine group) l-arginine analogs as substrates for NOS and measurement of radio-labeled l-citrulline and (15)N-labeled nitrite and nitrate, respectively. In the present work, we report on the development, validation and application of an UPLC-MS/MS method for the assessment of the activity of recombinant NOS enzymes by using [guanidino-(15)N2]-l-arginine (20?M for recombinant NOS, 5mM in cell systems) as the substrate and by measuring [ureido-(15)N]-l-citrulline as the reaction product (usually formed at concentrations below 1?M) using (2)H7-l-citrulline as the internal standard. The lower limit of detection of the method is about 80fmol (2)H7-l-citrulline. In cell systems, exceeding [guanidino-(15)N2]-l-arginine is removed by strong cation exchanger solid-phase extraction. The method was cross-validated by a GC-MS assay that measures simultaneously (15)N-nitrite and (15)N-nitrate as pentafluorobenzyl derivatives, with unlabeled nitrite and nitrate serving as the internal standards. By means of this UPLC-MS/MS (15)N-citrulline assay, N(G)-nitro-arginine (100?M) was found to inhibit recombinant inducible NOS (iNOS) activity (by 38%), whereas nitrite and GSSG (each at 500?M) did not affect iNOS activity at all. Nitrite and GSSG at pathophysiological concentrations are unlikely to uncouple NOS. NOS activity was not detectable in platelets of healthy humans by the UPLC-MS/MS and GC-MS assays. PMID:25033468

Böhmer, Anke; Gambaryan, Stepan; Flentje, Markus; Jordan, Jens; Tsikas, Dimitrios

2014-08-15

60

Rapid and high-throughput determination of endogenous cytokinins in Oryza sativa by bare Fe3O4 nanoparticles-based magnetic solid-phase extraction.  

PubMed

A rapid method was developed for determination of endogenous cytokinins (CKs) based on magnetic solid-phase extraction (MSPE) followed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). We illustrated the hydrophilic character of bare Fe3O4 nanoparticles that were directly used as a MSPE sorbent for rapid enrichment of endogenous CKs from complex plant extract. To the best of our knowledge, this is the first report of bare Fe3O4 directly used as efficient extraction sorbent to enrich target CKs based on hydrophilic interaction. Under the optimized conditions, a rapid, sensitive and high-throughput method for the determination of 16 CKs was established by combination of MSPE with UPLC-MS/MS. Good linearity was obtained with correlation coefficients (r) from 0.9902 to 0.9998. The limits of detection (LODs) and quantification (LOQs) ranged from 1.2pgmL(-1) to 391.3pgmL(-1) and 4.1pgmL(-1) to 1304.3pgmL(-1), respectively. 16 CKs could be successfully determined in spiked sample with 80.6-117.3% recoveries and the relative standard deviations (RSDs) were less than 16.6%. Finally, 10 endogenous CKs were successfully quantified in 50mg Oryza sativa sample using the developed MSPE-UPLC-MS/MS method. PMID:24685168

Cai, Bao-Dong; Zhu, Jiu-Xia; Gao, Qiang; Luo, Dan; Yuan, Bi-Feng; Feng, Yu-Qi

2014-05-01

61

Ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS) for the rapid, simultaneous analysis of thiamin, riboflavin, flavin adenine dinucleotide, nicotinamide and pyridoxal in human milk.  

PubMed

A novel, rapid and sensitive ultra-performance liquid-chromatography tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous determination of several B-vitamins in human milk was developed. Resolution by retention time or multiple reaction monitoring (MRM) for thiamin, riboflavin, flavin adenine dinucleotide (FAD), nicotinamide and pyridoxal (PL) has been optimized within 2 min using a gradient of 10 mM ammonium formate (aq) and acetonitrile. Thiamin-(4-methyl-¹³C-thiazol-5-yl-¹³C?) hydrochloride, riboflavin-dioxo-pyrimidine-¹³C?,¹?N?, and pyridoxal-methyl-d? hydrochloride were used as internal standards. A sample-like matrix was found to be mandatory for the external standard curve preparation. ¹³C?-caffeine was added for direct assessment of analyte recovery. Intra- and inter-assay variability for all analytes ranged from 0.4 to 7.9% and from 2.2 to 5.2%, respectively. Samples were subjected to protein precipitation and removal of non-polar constituents by diethyl ether prior to analysis. Quantification was done by ratio response to the stable isotope labeled internal standards. The standard addition method determined recovery rates for each vitamin (73.0-100.2%). The limit of quantitation for all vitamins was between 0.05 and 5 ppb depending on the vitamin. Alternative approaches for sample preparation such as protein removal by centrifugal filter units, acetonitrile or trichloroacetic acid revealed low recovery and a greater coefficient of variation. Matrix effect studies indicated a significant influence by matrix constituents, showing the importance of stable isotope labeled internal standards for analyte quantitation in complex matrices. PMID:22819611

Hampel, Daniela; York, Emily R; Allen, Lindsay H

2012-08-15

62

Development and full validation of an UPLC-MS/MS method for the determination of an anti-allergic indolinone derivative in rat plasma, and application to a preliminary pharmacokinetic study.  

PubMed

The natural product (E,Z)-3-(4-hydroxy-3,5-dimethoxybenzylidene)indolin-2-one (indolinone) was identified some years ago as a nanomolar inhibitor of Fc?RI-receptor dependent mast cell degranulation. To further explore the potential of the compound, we established an UPLC-MS/MS assay for dosage in rat plasma. The method was fully validated according to FDA Guidance for industry. Results of this validation and long term stability study demonstrate that the method in lithium heparinized rat plasma is specific, accurate, precise and capable of producing reliable results according to recommendations of international guidelines. The method was validated with a LLOQ of 30.0 ng/mL and an ULOQ of 3000 ng/mL. The response versus concentration data were fitted with a first order polynomial with 1/X(2) weighting. No matrix effect was observed when using three independent sources of rat plasma. The average extraction recovery was consistent over the investigated range. This validation in rat plasma demonstrated that indolinone was stable for 190 days when stored below -65 °C; for 4 days at 10 °C in the autosampler; for 4h at RT, and during three successive freeze/thaw cycles at -65 °C. Preliminary pharmacokinetic data were obtained in male Sprague-Dawley rats (2 mg/kg BW i.v.). Blood samples taken from 0 to 12 h after injection were collected, and data analyzed with WinNonlin. A short half-life (4.30±0.14 min) and a relatively high clearance (3.83±1.46 L/h/kg) were found. PMID:22770782

Oufir, Mouhssin; Sampath, Chethan; Butterweck, Veronika; Hamburger, Matthias

2012-08-01

63

Determination of Serotonin and Dopamine Metabolites in Human Brain Microdialysis and Cerebrospinal Fluid Samples by UPLC-MS/MS: Discovery of Intact Glucuronide and Sulfate Conjugates  

PubMed Central

An UPLC-MS/MS method was developed for the determination of serotonin (5-HT), dopamine (DA), their phase I metabolites 5-HIAA, DOPAC and HVA, and their sulfate and glucuronide conjugates in human brain microdialysis samples obtained from two patients with acute brain injuries, ventricular cerebrospinal fluid (CSF) samples obtained from four patients with obstructive hydrocephalus, and a lumbar CSF sample pooled mainly from patients undergoing spinal anesthesia in preparation for orthopedic surgery. The method was validated by determining the limits of detection and quantification, linearity, repeatability and specificity. The direct method enabled the analysis of the intact phase II metabolites of 5-HT and DA, without hydrolysis of the conjugates. The method also enabled the analysis of the regioisomers of the conjugates, and several intact glucuronide and sulfate conjugates were identified and quantified for the first time in the human brain microdialysis and CSF samples. We were able to show the presence of 5-HIAA sulfate, and that dopamine-3-O-sulfate predominates over dopamine-4-O-sulfate in the human brain. The quantitative results suggest that sulfonation is a more important phase II metabolism pathway than glucuronidation in the human brain.

Suominen, Tina; Uutela, Paivi; Ketola, Raimo A.; Bergquist, Jonas; Hillered, Lars; Finel, Moshe; Zhang, Hongbo; Laakso, Aki; Kostiainen, Risto

2013-01-01

64

A rapid miniaturized residue analytical method for the determination of zoxamide and its two acid metabolites in ginseng roots using UPLC-MS/MS.  

PubMed

A miniaturized residue method was developed for the analysis of the fungicide zoxamide and its metabolites in dried ginseng root. The zoxamide metabolites, 3,5-dichloro-1,4-benzenedicarboxylic acid (DCBC) and 3,5-dichloro-4-hydroxymethylbenzoic acid (DCHB), are small acid molecules that have not been previously extracted from the ginseng matrix with common multiresidue methods. The presented extraction method effectively and rapidly recovers both the zoxamide parent compound and its acid metabolites from fortified ginseng root. The metabolites are extracted with an alkaline glycine buffer and the aqueous ginseng mixture is partitioned with ethyl acetate. In addition, this method avoids the use of derivatization of the small acid molecules by using UPLC-MS/MS instrumental analysis. In a quantitative validation of the analytical method at three levels for zoxamide (0.007 (LOD), 0.02 (LOQ), and 0.2 mg/kg) and four levels (0.07 (LOD), 0.2 (LOQ), and 0.6 and 6 mg/kg) for both metabolites, acceptable method performances were achieved with recoveries ranging from 86 to 107% (at levels of LOQ and 3×, 10×, and 30× the LOQ) with <20% RSD for the three analytes in accordance with international guidelines.1. PMID:24552297

Podhorniak, Lynda V

2014-04-30

65

[Metabonomic study on the anti-liver injury effect of Si-Ni-San on rats by using UPLC-MS/MS].  

PubMed

A UPLC-MS/MS method based on metabonomic skills was developed to study the serum metabolic changes of rats after acute liver injury induced by CCl4 and to evaluate the action mechanism of Si-Ni-San. The integrated data were exported for principal components analysis (PCA) by using SIMCA-P software, in order to find the potential biomarkers. It showed that clear separation of healthy control group, model group, silymarin group, Si-Ni-San group was achieved by using the PCA method. Nine significantly changed metabolites were identified as potential biomarkers of acute liver injury. Compared with the health control group, the model group rats showed higher levels of phenylalanine, tryptophan and GCDCA together with lower levels of LPC 16 : 0, LPC 18 : 0, LPC 18 : 1, LPC 16 : 1, LPC 20 : 4 and LPC 22 : 6. These changes of serum metabolites suggested that the disorders of amino acid metabolism, lipid metabolism, bile acid biosynthesis and anti-oxidative damage were related to acute liver injury induced by CCl4. Si-Ni-San might have the anti-liver injury effect on all these four metabolic pathways. PMID:24961109

Yang, Li-Na; Wen, Jing; Sun, Yi; Liang, Jia-Jia; Zheng, Wei-Hua; Zhang, Li-Li; Zhou, Yu-Jie; Xiong, Zhi-Li

2014-03-01

66

Development of a rapid UPLC-MS/MS method for quantification of saxagliptin in rat plasma and application to pharmacokinetic study.  

PubMed

A novel, simple and rapid ultraperformance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) assay was established for quantification of saxagliptin in rat plasma. Plasma samples were processed by liquid-liquid extraction with ethyl acetate and chromatographed on a C?? column (2.1?×?50?mm i.d., 1.7?µm). The mobile phase consisted of methanol and 0.1% formic acid (40:60, v/v). Multiple reaction monitoring transitions were performed for detection in positive-ion mode with an electrospray ionization source. The calibration curve was linear over the concentration range of 0.5-100?ng/mL (R² ?>?0.99). All accuracy values were between 90.62 and 105.60% relative error and the intra- and inter-day precisions were less than 9.66% relative standard deviation. Extraction recovery was more than 81.01% and the matrix effect ranged from 90.27 to 109.15%. After validation, the method was applied to a pharmacokinetic study where healthy rats were orally given 0.5?mg/kg saxagliptin. PMID:22334441

Gao, Jing-wen; Yuan, Yue-mei; Lu, Ya-song; Yao, Mei-cun

2012-12-01

67

An UPLC-MS/MS method for the determination of valproic acid in blood of a fatal intoxication case.  

PubMed

Valproic acid (VPA) has been used as an anticonvulsant for the treatment of epilepsy. The authors present a fatal case involving a 45-year-old female, found dead lying in bed with empty tablets of Diplexil(®) next to her. She was a chronic alcoholic and epileptic who had been under psychiatric treatment, having repeatedly demonstrated intent to commit suicide. A rapid method was developed and validated to determine VPA in blood by ultra-performance liquid chromatography (UPLC) coupled with tandem mass spectrometry (MS/MS) with electrospray ionization source in negative ion mode. The method involved sample treatment with phosphoric acid followed by solid-phase extraction. Chromatographic separation was achieved using an Acquity UPLC(®) BEH (2.1 × 50 mm id, 1.7 ?m) column and a mobile phase containing ammonium acetate and acetonitrile, at a 0.5 mL/min flow rate. Detection and quantification of VPA was achieved using multiple reaction monitoring (MRM). The MS/MS transitions used for monitoring were m/z 143.1-143.1 for valproic acid and m/z 296.1-205.0 for hydrochlorothiazide used as an internal standard (IS). The limit of quantification (LOQ) was 0.5 ?g/mL and the method was linear in the concentration range of 0.5-100 ?g/mL. The coefficients of variation obtained for accuracy and precision were less than 10% and the mean recovery was 95% for the three concentrations levels studied (5 ?g/mL, 10 ?g/mL and 50 ?g/mL). Toxicological results showed high concentration of VPA (556 ?g/mL) and therapeutic concentrations of tiapride, mirtazapine, oxazepam and nordiazepam. Blood sample analysis also revealed the presence of ethanol at a concentration of 1.34 g/L. A specific, selective and sensitive method for the determination of VPA in blood was developed and can be used in routine forensic investigation. Toxicological results led the pathologist to rule that death was due to an intoxication caused by the simultaneous ingestion of high VPA concentrations and alcohol, with a suicidal legal-medical etiology. PMID:21907937

Proença, Paula; Franco, João Miguel; Mustra, Carla; Marcos, Mariana; Pereira, Ana Rita; Corte-Real, Francisco; Vieira, Duarte Nuno

2011-10-01

68

UPLC–MS–MS Analysis of Baicalin in the Cerebrospinal Fluid of Rabbits: Application to a Pharmacokinetic Study  

Microsoft Academic Search

A sensitive and selective ultra-performance liquid chromatographic–tandem mass spectrometric method has been developed for\\u000a analysis of baicalin in the cerebrospinal fluid of rabbits. Samples were separated on a C18 column with a gradient prepared from acetonitrile and 0.3% aqueous formic acid solution as mobile phase. The target compounds\\u000a were quantified by multiple reaction monitoring (MRM) using electrospray ionization (ESI). Intra-and

Shao Liu; Xin-Zhong Li; Li-Min Xu; Peng Lei; Yi-Zeng Liang

2008-01-01

69

Antioxidant properties and quantitative UPLC-MS analysis of phenolic compounds from extracts of fenugreek (Trigonella foenum-graecum) seeds and bitter melon (Momordica charantia) fruit.  

PubMed

Freeze-dried fenugreek (Trigonella foenum-graecum) seeds and bitter melon (Momordica charantia) fruit were extracted sequentially using non-polar to polar solvents, with further separation carried out on polar extracts by molecular weight cut off dialysis. The fenugreek ethyl acetate crude extract (FGE3) demonstrated the highest antioxidant activity, in terms of Trolox Equivalents (TE), for both the DPPH (35.338±0.908 mg TE/g) and FRAP (77.352±0.627 mg TE/g) assays. This extract also contained the highest phenolic content, in terms of Gallic Acid Equivalents (GAE) (106.316±0.377 mg GAE/g). Despite having considerably lower antioxidant activity than fenugreek, the highest antioxidant activities for bitter fruit were observed in the hexane (BME1) and methanol hydrophilic<3.5 kDa dialysed (BME4<3.5 kDa) extracts, while the highest phenolic content was found in the methanol hydrophilic>3.5 kDa (BME4>3.5 kDa) dialysed extract. UPLC-MS was used to quantify 18 phenolic compounds from fenugreek and 13 from bitter melon in active crude extracts. The flavonoids apigenin-7-O-glycoside (1955.55 ng/mg) and luteolin-7-O-glycoside (725.50 ng/mg) were the most abundant compounds in FGE3, while bitter melon extracts contained only small amounts of mainly phenolic acids. A further 5 fenugreek and 1 bitter melon compounds were identified in trace amounts from the same extracts, respectively. PMID:23993618

Kenny, O; Smyth, T J; Hewage, C M; Brunton, N P

2013-12-15

70

Urinary Metabolic Biomarker and Pathway Study of Hepatitis B Virus Infected Patients Based on UPLC-MS System  

PubMed Central

Hepatitis B virus (HBV) is the fatal consequence of chronic hepatitis, and lack of biomarkers has been a long standing bottleneck in the clinical diagnosis. Metabolomics concerns with comprehensive analysis of small molecules and provides a powerful approach to discover biomarkers in biological systems. Here, we present metabolomics analysis applying ultra-performance liquid chromatography/electrospray ionization quadruple time-of-flight mass spectrometry. (UPLC-Q-TOF-HDMS) to determine metabolite alterations in HBV patients. Most important permutations are elaborated using multivariate statistical analysis and network analysis that was used to select the metabolites for the noninvasive diagnosis of HBV. In this study, the total 11 urinary differential metabolites were identified and contributed to HBV progress involving several key metabolic pathways by using pathway analysis with MetPA, which are promising biomarker candidates for diagnostic research. More importantly, of 11 altered metabolites, 4 metabolite markers were effective for the diagnosis of human HBV, achieved a satisfactory accuracy, sensitivity and specificity, respectively. It demonstrates that metabolomics has the potential as a non-invasive tool to evaluate the potential of these metabolites in the early diagnosis of HBV patients. These findings may be promising to yield a valuable insight into the pathophysiology of HBV and to advance the approaches of diagnosis, treatment, and prevention.

Zhang, Aihua; Sun, Hui; Han, Ying; Yan, Guangli; Wang, Xijun

2013-01-01

71

Development and validation of UPLC-MS/MS method for simultaneous determination of gestodene and ethinyl estradiol in rat plasma.  

PubMed

A selective and sensitive ultra-performance liquid chromatography method with tandem mass spectrometric detection for simultaneous determination of gestodene (GES) and ethinyl estradiol (EE) in rat plasma was developed and validated. GES, EE and the internal standard, norgestrel, were extracted with ethyl acetate, derivatized (EE only) with dansyl chloride and then back-extracted into diethyl ether-hexane (2:1, v/v). The separation was performed on an ACQUITY UPLC BEH C(18) column with gradient elution using mobile phase consisting of acetonitrile and water (both containing 0.1% formic acid). The detection was carried out by means of electrospray ionization (ESI) mass spectrometry in positive ion mode with multiple-reaction monitoring. Calibration curves of GES and EE were linear (r(2) >or= 0.99) over the concentration ranges 1.59-159 and 0.196-78.4 ng/mL, respectively. The intra- and inter-day precisions were not more than 6.9 and 12.9% for GES and 10.6 and 9.0% for EE, and the accuracies were -2.5-8.0% for GES, and -7.2-0.19% for EE, respectively. The method herein described was superior to previous methods and was applicable to the pharmacokinetic study of GES and EE in rats. PMID:19591119

Xiong, Zhili; Sun, Xiaohong; Huo, Taoguang; Li, Ning; Zheng, Yan; Sun, Yi

2010-02-01

72

Advantages of online SPE coupled with UPLC/MS/MS for determining the fate of pesticides and pharmaceutical compounds.  

PubMed

Laboratory experimentation is essential for our understanding of the fate and behaviour of pollutants. Many analytical techniques exist, but they all have disadvantages either in terms of sensitivity or of selectivity. The number of samples that can be analysed, the low volume of samples available during the experiment and the need to identify different degradates are all obstacles that new techniques are able to overcome. The work presented here summarizes progress in the field of metrology as concerns online solid phase extraction technology coupled with liquid chromatography followed by tandem mass spectrometry detection. Recently developed analytical techniques were validated for both 18 pesticides and their degradates and 17 pharmaceuticals and their degradates. Limits of quantification from 20 to 70 ng L(-1) for pharmaceuticals and from 15 to 25 ng L(-1) for pesticides and metabolites have been obtained, with linearity range up to 1 ?g L(-1). The limits of quantification of a few nanograms per litre, the possibility of working on less than 1 mL of sample and the simultaneous quantification of the target products and their transformation products are all advantages that are demonstrated by two environmental applications. The first application concerns the evaluation of ecotoxicological effects of pesticides on aquatic organisms exposed in mesocosms. The second application aims to determine the adsorption constants of pharmaceutical molecules on soils and river sediments. For both applications, the robustness, range of linearity and limit of quantification of the developed analytical methods satisfy the requirements for laboratory experiments conducted under controlled conditions. Specific constraints generated by this type of experiment (adding CaCl2 for the adsorption study and filtration of the water coming from the mesocosms) were not found to limit the use of online SPE. These two preliminary studies show that new experimental fields are possible thanks to online solid phase extraction coupled with liquid chromatography. PMID:23907687

Togola, Anne; Baran, Nicole; Coureau, Charlotte

2014-02-01

73

Assessment of nicotine for second hand smoke exposure in some public places in Romania by UPLC-MS  

PubMed Central

Background Air nicotine monitoring is a well-known procedure for estimation of exposure to second hand smoke. Few research studies were realized in Romania to evaluate environmental tobacco smoke (ETS) exposure of humans in different public places. The levels of airborne nicotine from environmental tobacco smoke and urinary cotinine and nicotine levels of some subjects were analyzed. In order to better implement/enforce the European legislation regarding the interdiction of smoking in the public places the national authorities need a rapid and reliable analytical method to quickly asses the state of the pollution with cigarette smoke of these populated areas. Results The nicotine concentration in the air from different types of public buildings was determined. The median concentration of nicotine in the air from 32 pubs where the smoking was allowed was 590 ng?·?L-1, comparing with the pubs where the smoking was not permitted (22 locations) where the median concentration of nicotine was only 32 ng?·?L-1. Similarly, the median concentration of nicotine in restaurants where the smoking was allowed (23 locations) was 510 ng?·?L-1, in comparison with the restaurants where the smoking was prohibited (11 places) where the median value was 19 ng?·?L-1. The lowest concentrations of nicotine were found in high schools (8 locations, median concentration 7.4 ng?·?L-1), universities (5 locations, 23 ng?·?L-1) and hospitals (6 locations, 16 ng?·?L-1). Conclusions The method was validated and gave good linearity, precision, accuracy and limit of detection. The buildings included hospitals, high schools, universities, pubs and restaurants. The presence of air nicotine was recorded in all buildings studied. The highest median levels of air nicotine were found in pubs and restaurants. The presence of air nicotine in indoor public buildings indicates weak implementation of the smoke free law in Romania.

2014-01-01

74

Development and validation of an UPLC-MS/MS method for the determination of ionophoric and synthetic coccidiostats in vegetables.  

PubMed

In poultry farming, anticoccidial drugs are widely used as feed additives for the prevention and treatment of coccidiosis. Because coccidiostats and veterinary medicines, in general, are often poorly absorbed, manure from treated animals may contain high concentrations of these compounds. Experimental studies have shown that the uptake of veterinary medicines by plants from soil containing contaminated manure may occur. This leads to several questions regarding the impact on the environment, resistance problems, and public health and allergy issues. This work describes the development of a quantification method for coccidiostats in vegetables. Vegetables were spiked at 100 ?g kg(-1) (dry weight) with coccidiostats (monensin, narasin, lasalocid A, salinomycin, diclazuril, and nicarbazin) in order to optimize the extraction and clean-up. Possible critical factors (e.g., extraction solvent) were statistically examined by linear regression with the use of Plackett-Burman and full factorial designs. Final extracts were analyzed with ultra-performance liquid chromatography tandem mass spectrometry operating in multiple-reaction monitoring mode. Both the synthetic and ionophoric coccidiostats could be determined in a single run with an analysis time of 5 min. The developed method was validated taking into account the requirements of the Commission Decision 2002/657/EC as a guideline. The method is regarded as applicable for its intended purposes with quantification limits between 0.30 and 2.98 ?g kg(-1). This method could be used to establish possible maximum residue limits for coccidiostats in vegetables, as already exist for eggs, meat, and milk. PMID:21984012

Broekaert, N; Van Peteghem, C; Daeseleire, E; Sticker, D; Van Poucke, C

2011-12-01

75

Simultaneous determination of caffeic acid derivatives by UPLC-MS/MS in rat plasma and its application in pharmacokinetic study after oral administration of Flos Lonicerae-Fructus Forsythiae herb combination.  

PubMed

The current study aims to investigate the pharmacokinetic study of eight caffeic acid derivatives (forsythoside A, isoforsythoside, forsythoside B, neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, 3,5-dicaffeoylquinic acid and 3,4-dicaffeoylquinic acid) following oral administration of Flos Lonicerae-Fructus Forsythiae herb combination in rats. A rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to determine the eight caffeic acid derivatives simultaneously in rat plasma. After mixing with the internal standard (IS) tinidazole, plasma samples were pretreated by liquid-liquid extraction with n-butyl alcohol/ethyl acetate (7:3, v/v). The separation was performed on an Acquity UPLC HSS T3 C18 column (100mm×2.1mm, 1.8?m) at a flow rate of 0.4mLmin(-1), and acetonitrile/methanol (4:1, v/v)-0.4% formic acid was used as mobile phase. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) via electrospray ionization (ESI) source with positive and negative ionization modes. All calibration curves had good linearity (r>0.991) over the concentration ranges of 1.097-2246ngmL(-1) for neochlorogenic acid, 6.535-6692ngmL(-1) for chlorogenic acid, 2.103-2153ngmL(-1) for cryptochlorogenic acid, 0.5058-129.5ngmL(-1) for 3,5-dicaffeoylquinic acid, 0.3205-82.05ngmL(-1) for 3,4-dicaffeoylquinic acid, 1.002-512.8ngmL(-1) for isoforsythoside, 0.4795-982.1ngmL(-1) for forsythoside A and 0.7587-776.9ngmL(-1) for forsythoside B, respectively. The intra- and inter-batch precisions were all within 15% and the accuracy (relative error, RE%) all ranged from 85.68% to 114.7%. It was shown from pharmacokinetic parameters that the rank order of AUC0-t, Cmax and T1/2k for phenolic acids was chlorogenic acid>neochlorogenic acid?cryptochlorogenic acid>3,4-dicaffeoylquinic acid?3,5-dicaffeoylquinic acid (most of them had significant differences), which corresponded to their administration dosages to rats, but that of MRT0-t and T1/2z were opposite. Besides, the AUC0-t, Cmax, MRT and T1/2z except T1/2k of isoforsythoside and forsythoside B had no significant difference, compared to that of forsythoside A though their administration dosages were significantly lower than that of forsythoside A. All results showed that the method was applied to the pharmacokinetic study of the eight caffeic acid derivatives in rat plasma successfully after oral administration of Flos Lonicerae-Fructus Forsythiae herb combination, and there were significant differences of caffeic acid derivatives even isomers in the pharmacokinetic parameters. PMID:24441018

Zhou, Wei; Shan, Jinjun; Wang, Shouquan; Ju, Wenzheng; Meng, Minxin; Cai, Baochang; Di, Liuqing

2014-02-15

76

[Rapid simultaneous screening and detection of ten anticoagulant rodenticides in foods by ultra-high performance liquid chromatography-tandem mass spectrometry].  

PubMed

A rapid method for the simultaneous screening and detection of ten anticoagulant rodenticides in foods was developed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After the extraction by acetonitrile and clean-up by QuEChERS, the extract was separated on a Poroshell 120 EC-C18 column (100 mm x 2.1 mm, 2.7 microm) with the gradient elution of 5 mmol/L ammonium acetate and acetonitrile. The detection was carried out by UPLC-MS/MS using a negative electrospray ionization interface in multiple reaction monitoring (MRM) mode. The ten anticoagulant rodenticides showed a good linear relationship (r > 0.99) in the range of 5 - 500 microg/L. In the four samples of chili sauce, flour, vinegar and soy sauce, the spiked recoveries were in the range of 72.6% - 112%, and the relative standard deviations (RSD) were all not more than 11.2%. The limits of detection (LOD) were all in the range of 0.5 - 4.5 microg/kg. This method is rapid, simple, sensitive, accurate and of good specificity for the satisfactory rapid screening and detection of the ten anticoagulant rodenticides in the sudden public health security events. PMID:24010349

Zhu, Feng; Liu, Hualiang; Chen, Bei; Rong, Weiguang; Ma, Yongjian

2013-05-01

77

Validation of a novel in vitro assay using ultra performance liquid chromatography-mass spectrometry (UPLC/MS) to detect and quantify hydroxylated metabolites of BDE-99 in rat liver microsomes.  

PubMed

The purpose of this study was to develop and validate an ultra performance liquid chromatography-mass spectrometry (UPLC/MS) method to investigate the hepatic oxidative metabolism of 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), a widely used flame retardant and ubiquitous environmental contaminant. Hydroxylated metabolites were extracted using liquid-to-liquid extraction, resolved on a C18 column with gradient elution and detected by mass spectrometry in single ion recording mode using electrospray negative ionization. The assay was validated for linearity, accuracy, precision, limit of quantification, range and recovery. Calibration curves were linear (R2 > or = 0.98) over a concentration range of 0.010-1.0 microM for 4-OH-2,2',3,4',5-pentabromodiphenyl ether (4-OH-BDE-90), 5'-OH-2,2',4,4',5-pentabromodiphenyl ether (5'-OH-BDE-99) and 6'-OH-2,2',4,4',5-pentabromodiphenyl ether (6'-OH-BDE-99), and a concentration range of 0.0625-12.5 microM for 2,4,5-tribromophenol (2,4,5-TBP). Inter- and intra-day accuracy values ranged from -2.0% to 6.0% and from -7.7% to 7.3%, respectively, and inter- and intra-day precision values ranged from 2.0% to 8.5% and from 2.2% to 8.6% (n=6), respectively. The limits of quantification were 0.010 microM for 4-OH-BDE-90, 5'-OH-BDE-99 and 6'-OH-BDE-99, and 0.0625 microM for 2,4,5-TBP. Recovery values ranged between 85 and 100% for the four analytes. The validated analytical method was applied to identify and quantify hydroxy BDE-99 metabolites formed in vitro. Incubation of BDE-99 with rat liver microsomes yielded 4-OH-BDE-90 and 6'-OH-BDE-99 as major metabolites and 5'-OH-BDE-99 and 2,4,5-TBP as minor metabolites. To our knowledge, this is the first validated UPLC/MS method to quantify hydroxylated metabolites of PBDEs without the need of derivatization. PMID:20451473

Erratico, Claudio A; Szeitz, András; Bandiera, Stelvio M

2010-06-01

78

Radix Paeoniae Rubra and Radix Paeoniae Alba Attenuate CCl4-Induced Acute Liver Injury: An Ultra-Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS) Based Metabolomic Approach for the Pharmacodynamic Study of Traditional Chinese Medicines (TCMs)  

PubMed Central

Metabolomics has been frequently used in pharmacodynamic studies, especially those on traditional Chinese medicine (TCM). Radix Paeoniae Alba and Radix Paeoniae Rubra are popularly used in TCM, and both have hepatoprotective effects. In this study, a CCl4-induced acute liver injury rat model was established and confirmed by the observed serum aminotransferase activities. The metabolomics approach was applied to study the influence of Radix Paeoniae Alba and Radix Paeoniae Rubra on the metabolic changes in rats with acute liver injury. The partial least-squares-discriminant analysis (PLS-DA) of rat serum and their ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) fingerprints allowed discrimination of controlled, acute liver injury-model rats after administration of the two types of TCMs. The time-dependent PLS-DA plots showed that the changes in the metabolic patterns of the rats, which were administered with the TCMs, had stabilized within 2 h after they received the intraperitoneal CCl4 injection. The results indicated the protective effect of TCMs against liver injury. Several potential biomarkers were detected and identified, which included creatine, deoxycholic acid, choline, 5-methylenetetrahydrofolate, folic acid, and glycocholic acid. The physiological significance of these metabolic changes was discussed.

Wang, Rui; Xiong, Ai-Zhen; Teng, Zhong-Qiu; Yang, Qi-Wei; Shi, Yan-Hong; Yang, Li

2012-01-01

79

Radix Paeoniae Rubra and Radix Paeoniae Alba Attenuate CCl4-Induced Acute Liver Injury: An Ultra-Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS) Based Metabolomic Approach for the Pharmacodynamic Study of Traditional Chinese Medicines (TCMs).  

PubMed

Metabolomics has been frequently used in pharmacodynamic studies, especially those on traditional Chinese medicine (TCM). Radix Paeoniae Alba and Radix Paeoniae Rubra are popularly used in TCM, and both have hepatoprotective effects. In this study, a CCl(4)-induced acute liver injury rat model was established and confirmed by the observed serum aminotransferase activities. The metabolomics approach was applied to study the influence of Radix Paeoniae Alba and Radix Paeoniae Rubra on the metabolic changes in rats with acute liver injury. The partial least-squares-discriminant analysis (PLS-DA) of rat serum and their ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) fingerprints allowed discrimination of controlled, acute liver injury-model rats after administration of the two types of TCMs. The time-dependent PLS-DA plots showed that the changes in the metabolic patterns of the rats, which were administered with the TCMs, had stabilized within 2 h after they received the intraperitoneal CCl(4) injection. The results indicated the protective effect of TCMs against liver injury. Several potential biomarkers were detected and identified, which included creatine, deoxycholic acid, choline, 5-methylenetetrahydrofolate, folic acid, and glycocholic acid. The physiological significance of these metabolic changes was discussed. PMID:23203085

Wang, Rui; Xiong, Ai-Zhen; Teng, Zhong-Qiu; Yang, Qi-Wei; Shi, Yan-Hong; Yang, Li

2012-01-01

80

UPLC-MS/MS assay for the simultaneous quantification of carvedilol and its active metabolite 4'-hydroxyphenyl carvedilol in human plasma to support a bioequivalence study in healthy volunteers.  

PubMed

An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed for the simultaneous determination of carvedilol and its pharmacologically active metabolite 4'-hydroxyphenyl carvedilol in human plasma using their deuterated internal standards (IS). Samples were prepared by solid-phase extraction using 100 ?L human plasma. Chromatographic separation of analytes was achieved on UPLC C18 (50 × 2.1 mm, 1.7 µm) column using acetonitrile-4.0 mM ammonium formate, pH 3.0 adjusted with 0.1% formic acid (78:22, v/v) as the mobile phase. The multiple reaction monitoring transitions for both the analytes and IS were monitored in the positive electrospray ionization mode. The method was validated over a concentration range of 0.05-50 ng/mL for carvedilol and 0.01-10 ng/mL for 4'-hydroxyphenyl carvedilol. Intra- and inter-batch precision (% CV) and accuracy for the analytes varied from 0.74 to 3.88 and 96.4 to 103.3% respectively. Matrix effect was assessed by post-column analyte infusion and by calculation of precision values (coefficient of variation) in the measurement of the slope of calibration curves from eight plasma batches. The assay recovery was within 94-99% for both the analytes and IS. The method was successfully applied to support a bioequivalence study of 12.5 mg carvedilol tablets in 34 healthy subjects. PMID:23483571

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

2013-08-01

81

Simultaneous determination of pyrimethanil, cyprodinil, mepanipyrim and its metabolite in fresh and home-processed fruit and vegetables by a QuEChERS method coupled with UPLC-MS/MS.  

PubMed

A QuEChERS procedure for the simultaneous determination of pyrimethanil, cyprodinil, mepanipyrim and its metabolite (M31) in fresh and processed fruit and vegetables was developed using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). The determination of the four target compounds was achieved in less than 6.0 min using an electrospray ionisation source in positive mode. The limits of detection (LODs) were below 0.4 ?g?kg?¹, while the limits of quantification (LOQs) did not exceed 1.5 ?g?kg?¹ for all studied matrices. Good linearity of the calibration curves was obtained over the range from 0.002 to 2 mg?kg?¹, with correlation coefficients higher than 0.999. The average recoveries of this method in apple, peach, cabbage and tomato at the five spiked levels (0.002, 0.01, 0.05, 0.20 and 2.0 mg?kg?¹) ranged from 81.5% to 107.3% with relative standard deviations (RSDs) in the range of 1.5-13.9% (n = 5) for all analytes. Residue levels of anilinopyrimidine fungicides in fresh and home-processed apple, peach, cabbage and tomato were also studied. The results indicate that residue levels are significantly reduced following washing, peeling and boiling, and there is no toxic metabolite of mepanipyrim (M31) which is detected during boiling. This study provides a theoretical basis for China to draw up maximum residue limits (MRLs) and protect consumers from the negative health effects of pesticide residues detected in fruit and vegetables. PMID:23410121

Liang, Xuyang; Liu, Xingang; Dong, Fengshou; Xu, Jun; Qin, Dongmei; Li, Yuanbo; Tian, Yingying; Zhang, Ying; Han, Yongtao; Zheng, Yongquan

2013-01-01

82

Direct quantitative analysis of a 20 kDa PEGylated human calcitonin gene peptide antagonist in cynomolgus monkey serum using in-source CID and UPLC-MS/MS.  

PubMed

PEGylation is a successful strategy to improve the pharmacokinetic and pharmaceutical properties of therapeutic peptides. However, quantitative analysis of PEGylated peptides in biomatrix by LC-MS/MS poses significant analytical challenge due to the polydispersity of the polyethylene glycol (PEG), and the multiple charge states observed for both the peptide and PEG moieties. In this report, a novel LC-MS/MS method for direct quantitative analysis of 20 kDa PEGylated CGRP[Cit, Cit] in cynomolgus monkey serum is presented. CGRP[Cit, Cit] is an investigational human calcitonin gene peptide receptor antagonist with amino acid sequence Ac -WVTH[Cit]LAGLLS[Cit]SGGVVRKNFVPT DVGPFAF-NH(2). In-source collision-induced dissociation (in-source CID) of 20 kDa PEGylated peptide was used to generate CGRP[Cit, Cit] fragment ions, among which the most abundant b(8)(+) ion was selected and measured as a surrogate for the 20 kDa PEGylated peptide. A solid phase extraction (SPE) method was used to extract the PEGylated peptides from the biomatrix prior to the UPLC-MS/MS analysis. This method achieved a lower limit of quantitation (LLOQ) of 5.00 ng/mL with a serum sample volume of 100 ?L, and was linear over the calibration range of 5.00 to 500 ng/mL in cynomolgus monkey serum. Intraday and interday accuracy and precision from QC samples were within ±15%. This method was successfully applied to a pharmacokinetic study of the 20 kDa PEGylated CGRP[Cit, Cit] in cynomolgus monkeys. PMID:21953269

Li, Hongyan; Rose, Mark J; Holder, Jerry Ryan; Wright, Marie; Miranda, Les P; James, Christopher A

2011-09-01

83

Metabonomic analysis of urine from rats after low-dose exposure to 3-chloro-1,2-propanediol using UPLC-MS.  

PubMed

To study the toxic effect of chronic exposure to 3-chloro-1,2-propanediol (3-MCPD) at low doses, a metabonomics approach based on ultrahigh-performance liquid chromatography and quadruple time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was performed. Two different doses of 3-MCPD (1.1 and 5.5mg/kg bw/d) were administered to Wistar rats for 120 days (1.1mg/kg bw/d: lowest observed adverse effect level [LOAEL]). The metabolite profiles and biochemical parameters were obtained at five time points after treatment. For the 3-MCPD-treated groups, a significant change in urinary N-acetyl-?-d-glucosaminidase and ?-d-galactosidase was detected on day 90, while some biomarkers based on the metabonomics, such as N-acetylneuraminic acid, N-acetyl-l-tyrosine, and gulonic acid, were detected on day 30. These results suggest that these biomarkers changed more sensitively and earlier than conventional biochemical parameters and were thus considered early and sensitive biomarkers of exposure to 3-MCPD; these biomarkers provide more information on toxicity than conventional biochemical parameters. These results might be helpful to investigate the toxic mechanisms of 3-MCPD and provide a scientific basis for assessing the effect of chronic exposure to low-dose 3-MCPD on human health. PMID:23522902

Liu, Liyan; He, Yujie; Lu, Huimin; Wang, Maoqing; Sun, Changhao; Na, Lixin; Li, Ying

2013-05-15

84

High-Sensitivity Spectrophotometry.  

ERIC Educational Resources Information Center

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.…

Harris, T. D.

1982-01-01

85

High specific monoclonal antibody production and development of an ELISA method for monitoring T-2 toxin in rice.  

PubMed

This research produced a highly-specific and sensitive anti-T-2 toxin monoclonal antibody (mAb), and developed a rapid and sensitive competitive indirect enzyme-linked immunosorbent assay (ELISA) method for monitoring T-2 toxin in rice. The mAb showed a negligible cross-reactivity value (CR) to most of the mycotoxins, and it could specifically bind to T-2 toxin without other mycotoxins, including HT-2 toxin (CR value at 3.08%), which exhibited a similar structure to T-2 toxin. The limit of detection (LOD) value, measured by IC10, was 5.80 ?g/kg. In spiked samples, mean recoveries ranged from 72.0% to 108.5% with intraday and interday variation less than 16.8 and 13.7%. This proposed protocol was significantly confirmed by a reliable ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method and significant correlation was obtained. PMID:24450660

Li, Yanshen; Luo, Xiangshu; Yang, Shupeng; Cao, Xingyuan; Wang, Zhanhui; Shi, Weimin; Zhang, Suxia

2014-02-19

86

Natural occurrence of fumonisins and ochratoxin A in some herbs and spices commercialized in Poland analyzed by UPLC-MS/MS method.  

PubMed

Unsanitary conditions during harvesting, drying, packing and storage stages in production and processing of spices and herbs could introduce mycotoxin contamination. The occurrence of ochratoxin A and fumonisins in popular spices and herbs was studied, using liquid chromatography-electrospray-mass spectrometry. Apart from mycotoxins, ergosterol as a factor indicating fungal development was also analysed. A total of 79 different samples commercialized in Poland were randomly purchased from popular markets were tested for mycotoxins. The frequency of samples with fumonisins was lower (31%) than ochratoxin A (49%). Free from mycotoxins were samples of bay leaf and white mustard. ERG content - in spice samples with high concentration level of mycotoxins - was also significantly higher than in samples with little to no mycotoxins. PMID:24010625

Wa?kiewicz, Agnieszka; Beszterda, Monika; Bocianowski, Jan; Goli?ski, Piotr

2013-12-01

87

Objective set of criteria for optimization of sample preparation procedures for ultra-high throughput untargeted blood plasma lipid profiling by ultra performance liquid chromatography-mass spectrometry.  

PubMed

Exploratory or untargeted ultra performance liquid chromatography-mass spectrometry (UPLC-MS) profiling offers an overview of the complex lipid species diversity present in blood plasma. Here, we evaluate and compare eight sample preparation protocols for optimized blood plasma lipid extraction and measurement by UPLC-MS lipid profiling, including four protein precipitation methods (i.e., methanol, acetonitrile, isopropanol, and isopropanol-acetonitrile) and four liquid-liquid extractions (i.e., methanol combined with chloroform, dichloromethane, and methyl-tert butyl ether and isopropanol with hexane). The eight methods were then benchmarked using a set of qualitative and quantitative criteria selected to warrant compliance with high-throughput analytical workflows: protein removal efficiency, selectivity, repeatability, and recovery efficiency of the sample preparation. We found that protein removal was more efficient by precipitation (99%) than extraction (95%). Additionally, isopropanol appeared to be the most straightforward and robust solvent (61.1% of features with coefficient of variation (CV) < 20%) while enabling a broad coverage and recovery of plasma lipid species. These results demonstrate that isopropanol precipitation is an excellent sample preparation procedure for high-throughput untargeted lipid profiling using UPLC-MS. Isopropanol precipitation is not limited to untargeted profiling and could also be of interest for targeted UPLC-MS/MS lipid analysis. Collectively, these data show that lipid profiling greatly benefits from an isopropanol precipitation in terms of simplicity, protein removal efficiency, repeatability, lipid recovery, and coverage. PMID:24820162

Sarafian, Magali H; Gaudin, Mathieu; Lewis, Matthew R; Martin, Francois-Pierre; Holmes, Elaine; Nicholson, Jeremy K; Dumas, Marc-Emmanuel

2014-06-17

88

Wipe selection for the analysis of surface materials containing chemical warfare agent nitrogen mustard degradation products by ultra-high pressure liquid chromatography-tandem mass spectrometry.  

PubMed

Degradation products arising from nitrogen mustard chemical warfare agent were deposited on common urban surfaces and determined via surface wiping, wipe extraction, and liquid chromatography–tandem mass spectrometry detection. Wipes investigated included cotton gauze, glass fiber filter, non-woven polyester fiber and filter paper, and surfaces included several porous (vinyl tile, painted drywall, wood) and mostly non-porous (laminate, galvanized steel, glass) surfaces. Wipe extracts were analyzed by ultra-high pressure liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) and compared with high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) results. An evaluation of both techniques suggests UPLC–MS/MS provides a quick and sensitive analysis of targeted degradation products in addition to being nearly four times faster than a single HPLC run, allowing for greater throughput during a wide-spread release concerning large-scale contamination and subsequent remediation events. Based on the overall performance of all tested wipes, filter paper wipes were selected over other wipes because they did not contain interferences or native species (TEA and DEA) associated with the target analytes, resulting in high percent recoveries and low background levels during sample analysis. Other wipes, including cotton gauze, would require a pre-cleaning step due to the presence of large quantities of native species or interferences of the targeted analytes. Percent recoveries obtained from a laminate surface were 47–99% for all nitrogen mustard degradation products. The resulting detection limits achieved from wipes were 0.2 ng/cm(2) for triethanolamine (TEA), 0.03 ng/cm(2) for N-ethyldiethanolamine (EDEA), 0.1 ng/cm(2) for N-methyldiethanolamine (MDEA), and 0.1 ng/cm(2) for diethanolamine (DEA). PMID:23218189

Willison, Stuart A

2012-12-28

89

High-Sensitivity Microwave Optics.  

ERIC Educational Resources Information Center

Describes a 3.33-cm wavelength (9 GHz) microwave system that achieves a high overall signal sensitivity and a well-collimated beam with moderate-size equipment. The system has been used to develop microwave versions of the Michelson interferometer, Bragg reflector, Brewster's law and total internal reflection, and Young's interference experiment.…

Nunn, W. M., Jr.

1981-01-01

90

High-speed solubility screening assay using ultra-performance liquid chromatography\\/mass spectrometry in drug discovery  

Microsoft Academic Search

Ultra-performance liquid chromatography (UPLC) was investigated as an alternative to high-performance liquid chromatography (HPLC) for analyzing pharmaceutical drug candidates. We previously developed a 96-well-based high-speed solubility assay system (HSSOL) using HPLC\\/UV and a LogD assay system (HSLogD) using HPLC\\/MS [Y. Dohta, T. Yamashita, S. Horiike, T. Nakamura, T. Fukami, Anal. Chem. 79 (2007) 8312]. We have introduced the UPLC\\/MS system

Taro Yamashita; Yukifumi Dohta; Tatsuji Nakamura; Takehiro Fukami

2008-01-01

91

Absolute quantification of UGT1A1 in various tissues and cell lines using isotope label-free UPLC-MS/MS method determines its turnover number and correlates with its glucuronidation activities.  

PubMed

Uridine 5'-diphosphate-glucuronosyltransferase (UGT)1A1 is a major phase II metabolism enzyme responsible for glucuronidation of drugs and endogenous compounds. The purpose of this study was to determine the expression level of UGT1A1 in human liver microsomes and human cell lines by using an isotope label-free LC-MS/MS method. A Waters Ultra performance liquid chromatography (UPLC) system coupled with an API 5500Qtrap mass spectrometer was used for the analysis. Two signature peptides (Pep-1, and Pep-2) were employed to quantify UGT1A1 by multiple reaction monitoring (MRM) approach. Standard addition method was used to validate the assay to account for the matrix effect. 17?-Estradiol was used as the marker substrate to determine UGT1A1 activities. The validated method has a linear range of 200-0.0195nM for both signature peptides. The precision, accuracy, and matrix effect were in acceptable ranges. UGT1A1 expression levels were then determined using 8 individual human liver microsomes, a pooled human liver microsomes, three UGT1A1 genotyped human liver microsomes, and four cell lines (Caco-2, MCF-7, Hela, and HepG2). The correlations study showed that the UGT1A1 protein levels were strongly correlated with its glucuronidation activities in human liver microsomes (R(2)=0.85) and in microsomes prepared from cell lines (R(2)=0.95). Isotope-labeled peptides were not necessary for LC-MS/MS quantitation of proteins. The isotope label-free absolute quantification method used here had good accuracy, sensitivity, linear range, and reproducibility, and were used successfully for the accurate determination of UGT1A1 from tissues and cell lines. PMID:24055854

Xu, Beibei; Gao, Song; Wu, Baojian; Yin, Taijun; Hu, Ming

2014-01-01

92

High sensitivity RNA pseudoknot prediction  

PubMed Central

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.

Huang, Xiaolu; Ali, Hesham

2007-01-01

93

UPLC-MS-based Urine Metabolomics Reveals Indole-3-lactic acid and Phenyllactic acid as Conserved Biomarkers for Alcohol-induced Liver Disease in the Ppara-null Mouse Model  

PubMed Central

Since the development and prognosis of alcohol-induced liver disease (ALD) vary significantly with genetic background, identification of a genetic background-independent noninvasive ALD biomarker would significantly improve screening and diagnosis. This study explored the effect of genetic background on the ALD-associated urinary metabolome using the Ppara-null mouse model on two different backgrounds, C57BL/6 (B6) and 129/SvJ (129S), along with their wild-type counterparts. Reversed-phase gradient UPLC-ESI-QTOF-MS analysis revealed that urinary excretion of a number of metabolites, such as, ethylsulfate, 4-hydroxyphenylacetic acid, 4-hydroxyphenylacetic acid sulfate, adipic acid, pimelic acid, xanthurenic acid, and taurine were background-dependent. Elevation of ethyl-?-D-glucuronide and N-acetylglycine was found to be common signature of the metabolomic response to alcohol exposure in wild-type as well as in Ppara-null mice of both strains. However, increased excretion of indole-3-lactic acid and phenyllactic acid was found to be a conserved feature exclusively associated with the alcohol-treated Ppara-null mouse on both backgrounds that develop liver pathologies similar to the early stages of human ALD. These markers reflected the biochemical events associated with early stages of ALD pathogenesis. The results suggest that indole-3-lactic acid and phenyllactic acid are potential candidates for conserved and pathology-specific high-throughput noninvasive biomarkers for early stages of ALD.

Manna, Soumen K.; Patterson, Andrew D.; Yang, Qian; Krausz, Kristopher W.; Idle, Jeffrey R.; Fornace, Albert J.; Gonzalez, Frank J.

2011-01-01

94

High-sensitivity nanosensors for biomarker detection†  

PubMed Central

High sensitivity nanosensors utilize optical, mechanical, electrical, and magnetic relaxation properties to push detection limits of biomarkers below previously possible concentrations. The unique properties of nanomaterials and nanotechnology are exploited to design biomarker diagnostics. High-sensitivity recognition is achieved by signal and target amplification along with thorough pre-processing of samples. In this tutorial review, we introduce the type of detection signals read by nanosensors to detect extremely small concentrations of biomarkers and provide distinctive examples of high-sensitivity sensors. The use of such high-sensitivity nanosensors can offer earlier detection of disease than currently available to patients and create significant improvements in clinical outcomes.

Swierczewska, Magdalena; Liu, Gang

2013-01-01

95

[Related substances in orlistat detected with UPLC-MS/MS].  

PubMed

The study aims to identify related substances in orlistat pharmaceutical substance from different production technologies. Advanced technologies including UPLC-QTOF-MS and UPLC-QTrap-MS were used and the structures or molecules of 10 kinds of related substances in orlistat were identified. The experimental data were valuable to the quality control and development of orlistat. PMID:24961111

Zhang, Ting-Ting; Ma, Chen

2014-03-01

96

Cryogenic High-Sensitivity Magnetometer  

NASA Technical Reports Server (NTRS)

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.

Day, Peter; Chui, Talso; Goodstein, David

2005-01-01

97

Nanopatterning and High Sensitivity Biodetection  

NASA Astrophysics Data System (ADS)

The Nanoscale Science and Engineering Center (NSEC) for Integrated Nanopatterning and Detection Technologies was established in September 2001 by NSF Award Number EEC-0118025. A cross-disciplinary effort, the NSEC brings together scientists, engineers, and educators from Northwestern University, University of Illinois at Urbana-Champaign, University of Chicago, Argonne National Laboratory, the Chicago Museum of Science and Industry, Harold Washington College, and twenty-four companies and business groups. The NSEC is working at the nanoscale to develop chemical and biological sensors that will be far more sensitive, selective, and cost-effective than conventional systems. These goals are pursued by an integrated team of three synergistic research groups: nanopatterning, integrated electronic chip, and optical nanoarray sensors. This talk will provide an overview and highlight recent developments in NSEC-supported research.

Hersam, Mark

2003-03-01

98

Electrostatic Sensitivity of Secondary High Explosives.  

National Technical Information Service (NTIS)

An Electrostatic Sensitivity Test System designed at Pantex was used to evaluate the secondary high explosives PETN, HMX, RDX, HNS I, HNS II and TATB. The purpose of this study was to establish test conditions for a standard electrostatic sensitivity test...

C. A. Campos

1980-01-01

99

Highly Sensitive Magnetic Flux Superconducting Detector.  

National Technical Information Service (NTIS)

The preliminary results on creation of a highly sensitive superconducting detector of magnetic flux with a toroidal sensor are presented in the paper. The real sensitivity of the detector is about 4x10 exp -11 gxcm exp 2 / sqrt Hz. The peculiarities of ba...

E. N. Ardashev G. I. Selivanov A. G. Kholodenko

1975-01-01

100

High-sensitivity microwave optics  

NASA Astrophysics Data System (ADS)

Microwave optics experiments operating at a 3.33-cm wavelength (9 GHz) are described that have an overall signal gain of 58 dB, which is achieved by using a 1000-Hz square-wave modulated reflex klystron and a high-gain, narrowband amplifier following a point-contact detector. A metal-plate electromagnetic lens is employed that has a gain of 22.5 dB relative to an isotropic radiator, produces a beam collimated to within 12 deg between half-power points, and has a 3.7% bandwidth around a center frequency of 9 GHz. This basic system was used to developed microwave versions of the Michelson interferometer, Bragg reflection, Brewter's law and total internal reflection, and Young's interference experiment. Measured radiation intensities for four signal sources are shown to lie well within Federal performance regulations established in 1971.

Nunn, W. M.

1981-12-01

101

High-throughput LC-MS/MS based simultaneous determination of polyamines including N-acetylated forms in human saliva and the diagnostic approach to breast cancer patients.  

PubMed

The determination of polyamines and their N-acetylated forms was performed by ultraperformance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The polyamines efficiently reacted with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) in 0.1 M borax (pH 9.3) at 60 °C for 30 min. The resulting derivatives were analyzed by electrospray ionization (ESI)-MS and sensitively detected by selected reaction monitoring (SRM). Furthermore, a rapid separation of the polyamine derivatives within 10 min was performed by UPLC using an antipressurized column packed with 1.7-?m octadecylsilyl (ODS) silica gel. The limits of detection (S/N = 3) on the SRM chromatograms were at the attomole level (9-43 amol). This procedure was used to successfully determine 11 polyamines, including their N-acetylated forms, in the saliva of patients with primary and relapsed breast cancer and healthy volunteers. The level of several polyamines (Ac-PUT, Ac-SPD, Ac-SPM, DAc-SPD, and DAc-SPM) increases in breast cancer patients. Furthermore, the levels of three polyamines (Ac-SPM, DAc-SPD, and DAc-SPM) were significantly higher only in the relapsed patients. The present method proved highly sensitive and is characterized by specificity and feasibility for sample analysis. Consequently, the proposed method is useful for the noninvasive salivary diagnosis of cancer patients and could be applied to determine polyamines in several specimens of biological nature. PMID:24274257

Tsutsui, Haruhito; Mochizuki, Toshiki; Inoue, Koichi; Toyama, Tatsuya; Yoshimoto, Nobuyasu; Endo, Yumi; Todoroki, Kenichiro; Min, Jun Zhe; Toyo'oka, Toshimasa

2013-12-17

102

High sensitivity radiation detector for capillary electrophoresis  

SciTech Connect

Capillary electrophoresis is an important new instrumental technique capable of high resolution separation and analysis of small quantities of nucleotides, amino acids, peptides, and proteins with very high efficiency and throughput. The unprecedented sensitivity of this technique will be useful for such new applications as in vivo labeling and identification of trace substances and single cell work. The principle limitation of this technique for radiolabeled molecules has been identified as the sensitivity of the detector, primarily due to the small sample volume (< 1 nl) and the short residence time of the sample in the detector (< 3 sec). The authors have developed a novel high-sensitivity CdTe solid-state detector used for detection of [sup 32]P-labeled biomolecules with unprecedented sensitivity. This detector can be easily retrofitted into existing CE apparatus.

Gordon, J.S.; Vasile, S.; Hazlett, T.; Squillante, M. (Radiation Monitoring Devices, Inc., Watertown, MA (United States))

1993-08-01

103

High sensitivity cymbal-based accelerometer  

SciTech Connect

A high sensitivity piezoelectric accelerometer has been developed by replacing the conventional piezoelectric rings with a cymbal transducer. The sensitivity of the cymbal-based accelerometers containing cymbal transducers with different endcap thicknesses and different seismic masses has been measured as a function of driving frequency. Due to the high d{sub 33}{sup '} coefficient of the cymbal transducers, the cymbal-based accelerometers have a high sensitivity of {approx}97 pC/ms{sup -2} with the amplitude rise of 2.85% (<1 dB) at one-third of the mounted resonance frequency (3.38 kHz). The effect of the seismic mass, the resonance frequency, and d{sub 33}{sup '} coefficient of the cymbal transducers on the sensitivity and the frequency range of the cymbal-based accelerometers are reported.

Sun Chengliang; Lam, K.H.; Choy, S.H.; Chan, H.L. W.; Zhao, X.-Z.; Choy, C.L. [Department of Applied Physics, Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong (China); Materials Research Center, Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong (China); Department of Physics, Wuhan University, Wuhan 430072 (China); and Center of Nanoscience and Nanotechnology, Wuhan University, Wuhan 430072 (China); Department of Applied Physics, Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong (China) and Materials Research Center, Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong (China); Department of Physics, Wuhan University, Wuhan 430072 (China) and Center of Nanoscience and Nanotechnology, Wuhan University, Wuhan 430072 (China); Department of Applied Physics, Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong (China) and Materials Research Center, Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong (China)

2006-03-15

104

High sensitivity optically pumped quantum magnetometer.  

PubMed

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 ?W 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. PMID:23766716

Tiporlini, Valentina; Alameh, Kamal

2013-01-01

105

High Sensitivity Optically Pumped Quantum Magnetometer  

PubMed Central

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??W 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/Hz1/2 over a bandwidth of 26?Hz and that this sensitivity drops to 130?pT/Hz1/2 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.

Tiporlini, Valentina; Alameh, Kamal

2013-01-01

106

Micromachined solenoids for highly sensitive magnetic sensors  

Microsoft Academic Search

Micromachined solenoids on silicon wafer for highly sensitive vector magnetic field sensors have been proposed. The feature of the solenoids is that the magnetic field is parallel to the wafer surface. In order to realize interconnections on three-dimensional structure, direct electron beam lithography was utilized. The formation of Mo interconnections was achieved on the surface of deep U-shaped grooves. Applications

S. Kawahito; Y. Sasaki; M. Ashiki; T. Nakamura

1991-01-01

107

Highly sensitive submillimeter InSb photodetectors  

SciTech Connect

Submillimeter photoconductivity of the electron gas in bulk InSb has been studied. A new design of the InSb photodetector in the form of planar coils with a length-to-width ratio of two orders of magnitude is suggested. This design enables fabrication of highly sensitive photodetectors with the responsivity peak tunable by magnetic field.

Vasilyev, Yu. B., E-mail: yu.vasilyev@mail.ioffe.ru; Usikova, A. A.; Il'inskaya, N. D.; Petrov, P. V.; Ivanov, Yu. L. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2008-10-15

108

Demonstration of High Sensitivity Laser Ranging System.  

National Technical Information Service (NTIS)

We report on a high sensitivity semiconductor laser ranging system developed for the Gravity and Magnetic Earth Surveyor (GAMES) for measuring variations in the planet's gravity field. The GAMES laser ranging instrument (LRI) consists of a pair of co-orbi...

1994-01-01

109

High blood pressure and visual sensitivity  

NASA Astrophysics Data System (ADS)

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.

Eisner, Alvin; Samples, John R.

2003-09-01

110

[Simultaneous determination of 20 illegally added anti-diabetic chemical components in hypoglycemic and weight-reducing health foods by ultra-high performance liquid chromatography-tandem mass spectrometry].  

PubMed

A rapid method for the simultaneous screening and detection of 20 illegally added anti-diabetic chemical components in hypoglycemic and weight-reducing health foods was developed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After extracted by methanol, the sample was separated on a Poroshell 120 EC C18 column (100 mm x 2.1 mm, 2.7 microm) with the gradient elution of 5 mmol/L ammonium acetate and acetonitrile as mobile phases. The electrospray ionization (ESI) source in positive or negative ion mode was used for multiple reaction monitoring (MRM) mode. The 20 illegally added chemical components showed good linear relationships with the correlation coefficients more than 0.99. The recoveries were in the range of 75.9% - 114.0%, and the relative standard deviations (RSDs) were all not more than 11.3%. The limits of detection (LODs) were all in the range of 0.3 - 1.5 microg/L. This method is rapid, simple, sensitive, accurate and of good specificity for cracking down illegally added anti-diabetic chemical components. PMID:24783863

Zhu, Feng; Ruan, Liping; Ma, Yongjian; Ji, Wenliang; Liu, Hualiang

2014-01-01

111

High sensitivity gas leak detection system  

Microsoft Academic Search

A new gas-leak-detection system owes its high sensitivity to a unique configuration of low-volume sample collectors. A corollary benefit of the arrangement is its portability: the entire unit can be easily hand-carried and rapidly attached to a rented car, for example, for use in distant or remote locations. The system incorporates numerous small-diameter flexible tubes aligned and directed toward the

Burkhart

1979-01-01

112

Demonstration of high sensitivity laser ranging system  

Microsoft Academic Search

We report on a high sensitivity semiconductor laser ranging system developed for the Gravity and Magnetic Earth Surveyor (GAMES) for measuring variations in the planet's gravity field. The GAMES laser ranging instrument (LRI) consists of a pair of co-orbiting satellites, one which contains the laser transmitter and receiver and one with a passive retro-reflector mounted in an drag-stabilized housing. The

Pamela S. Millar; Kent D. Christian; Christopher T. Field

1994-01-01

113

High sensitivity intravascular photoacoustic imaging of macrophages  

NASA Astrophysics Data System (ADS)

In atherosclerosis, tracking and locating the activity of macrophages that are highly involved in plaque development will help to identify the pathology of the disease. Intravascular photoacoustic (IVPA) imaging has shown potential to detect atherosclerosis and to determine plaque composition. Furthermore, using optical absorbers as contrast agents, IVPA can also be used for molecular imaging. In this paper, we study the feasibility of using gold nanoparticles as contrast agent for high sensitivity IVPA imaging of macrophages. The artery was modeled using a cylindrical tube made out of polyvinyl alcohol. Within the vessel wall, several compartments were made to mimic plaques. After incubating murine macrophages with 50 nm spherical gold nanoparticles overnight, macrophages loaded with particles were filled into the compartments of the arterial phantoms. Because of the plasmon resonance coupling of aggregated nanoparticles inside the macrophages, these macrophages can be detected by IVPA imaging using 680 nm wavelength. The sensitivity of the molecular IVPA imaging was tested using phantoms with different concentrations of nanoparticles and macrophages. Finally, to address the feasibility of in-vivo IVPA imaging with gold nanoparticles, the viability of the macrophages loaded with nanoparticles exposed to laser irradiation was studied. The results show that IVPA imaging can safely image macrophages loaded with gold nanoparticles with relatively high sensitivity.

Wang, Bo; Yantsen, Evgeniya; Sokolov, Konstantin; Emelianov, Stanislav

2009-02-01

114

Highly sensitive catalytic spectrophotometric determination of ruthenium  

NASA Astrophysics Data System (ADS)

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 (? 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.

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

2008-01-01

115

A high sensitivity small animal SPECT system  

PubMed Central

Medical imaging using single gamma ray emitting radionuclides typically makes use of parallel hole collimators or pinholes in order to achieve good spatial resolution. However, a tradeoff in sensitivity is inherent in the use of a collimator, and modern preclinical SPECT (single photon emission computed tomography) systems detect a very small fraction of emitted gamma rays, often less than 0.1%. A system for small animal SPECT imaging which uses no collimators could potentially achieve very high sensitivity—several tens of percent—with reasonably sized detectors. This would allow two significant improvements in preclinical studies: images could be obtained more rapidly, allowing higher throughput for screening applications, or for dynamic processes to be observed with very good time resolution; and images could be obtained with less radioactive tracer, making possible the in vivo imaging of low-capacity receptor systems, aiding research into new tracer compounds, and reducing the cost and easing the regulatory burden of an experiment. Of course, a system with no collimator will not be able to approach the sub-millimeter spatial resolutions produced by the most advanced pinhole and collimated systems, but a high sensitivity system with resolution of order one centimeter could nonetheless find significant and new use in the many molecular imaging applications which do not require good spatial resolution—for example, screening applications for drug development or new imaging agents. Rather than as an alternative to high resolution SPECT systems, the high sensitivity system is proposed as a radiotracer alternative to optical imaging for small animals. We have developed a prototype system for mouse imaging applications. The scanner consists of two large, thin, closely spaced scintillation detectors. Simulation studies indicate that a FWHM spatial resolution of 7 mm is possible. In an in vivo mouse imaging study using the 99mTc labeled tracer MAG-3, the sensitivity of the system is measured to be 40%. Simple projection images created by analytically combining the two detectors' data show sufficient resolution to observe the dynamic distribution of the radiotracer in the mouse.

Mitchell, Gregory S; Cherry, Simon R

2009-01-01

116

High sensitivity nanoparticle detection using optical microcavities  

PubMed Central

We demonstrate a highly sensitive nanoparticle and virus detection method by using a thermal-stabilized reference interferometer in conjunction with an ultrahigh-Q microcavity. Sensitivity is sufficient to resolve shifts caused by binding of individual nanobeads in solution down to a record radius of 12.5 nm, a size approaching that of single protein molecules. A histogram of wavelength shift versus nanoparticle radius shows that particle size can be inferred from shift maxima. Additionally, the signal-to-noise ratio for detection of Influenza A virus is enhanced to 38?1 from the previously reported 3?1. The method does not use feedback stabilization of the probe laser. It is also observed that the conjunction of particle-induced backscatter and optical-path-induced shifts can be used to enhance detection signal-to-noise.

Lu, Tao; Lee, Hansuek; Chen, Tong; Herchak, Steven; Kim, Ji-Hun; Fraser, Scott E.; Flagan, Richard C.; Vahala, Kerry

2011-01-01

117

Highly sensitive nanoscale spin-torque diode.  

PubMed

Highly sensitive microwave devices that are operational at room temperature are important for high-speed multiplex telecommunications. Quantum devices such as superconducting bolometers possess high performance but work only at low temperature. On the other hand, semiconductor devices, although enabling high-speed operation at room temperature, have poor signal-to-noise ratios. In this regard, the demonstration of a diode based on spin-torque-induced ferromagnetic resonance between nanomagnets represented a promising development, even though the rectification output was too small for applications (1.4?mV?mW(-1)). Here we show that by applying d.c. bias currents to nanomagnets while precisely controlling their magnetization-potential profiles, a much greater radiofrequency detection sensitivity of 12,000?mV?mW(-1) is achievable at room temperature, exceeding that of semiconductor diode detectors (3,800?mV?mW(-1)). Theoretical analysis reveals essential roles for nonlinear ferromagnetic resonance, which enhances the signal-to-noise ratio even at room temperature as the size of the magnets decreases. PMID:24141450

Miwa, S; Ishibashi, S; Tomita, H; Nozaki, T; Tamura, E; Ando, K; Mizuochi, N; Saruya, T; Kubota, H; Yakushiji, K; Taniguchi, T; Imamura, H; Fukushima, A; Yuasa, S; Suzuki, Y

2014-01-01

118

Highly sensitive nanoscale spin-torque diode  

NASA Astrophysics Data System (ADS)

Highly sensitive microwave devices that are operational at room temperature are important for high-speed multiplex telecommunications. Quantum devices such as superconducting bolometers possess high performance but work only at low temperature. On the other hand, semiconductor devices, although enabling high-speed operation at room temperature, have poor signal-to-noise ratios. In this regard, the demonstration of a diode based on spin-torque-induced ferromagnetic resonance between nanomagnets represented a promising development, even though the rectification output was too small for applications (1.4?mV?mW-1). Here we show that by applying d.c. bias currents to nanomagnets while precisely controlling their magnetization-potential profiles, a much greater radiofrequency detection sensitivity of 12,000?mV?mW-1 is achievable at room temperature, exceeding that of semiconductor diode detectors (3,800?mV?mW-1). Theoretical analysis reveals essential roles for nonlinear ferromagnetic resonance, which enhances the signal-to-noise ratio even at room temperature as the size of the magnets decreases.

Miwa, S.; Ishibashi, S.; Tomita, H.; Nozaki, T.; Tamura, E.; Ando, K.; Mizuochi, N.; Saruya, T.; Kubota, H.; Yakushiji, K.; Taniguchi, T.; Imamura, H.; Fukushima, A.; Yuasa, S.; Suzuki, Y.

2014-01-01

119

Cooled membrane for high sensitivity gas sampling.  

PubMed

A novel sample preparation method that combines the advantages of high surface area geometry and cold surface effect was proposed to achieve high sensitivity gas sampling. To accomplish this goal, a device that enables the membrane to be cooled down was developed for sampling, and a gas chromatograph-mass spectrometer was used for separation and quantification analysis. Method development included investigation of the effect of membrane temperature, membrane size, gas flow rate and humidity. Results showed that high sensitivity for equilibrium sampling, such as limonene sampling in the current study could be achieved by either cooling down the membrane and/or using a large volume extraction phase. On the other hand, for pre-equilibrium extraction, in which the extracted amount was mainly determined by membrane surface area and diffusion coefficient, high sensitivity could be obtained by using thinner membranes with a larger surface and/or a higher sampling flow rate. In addition, humidity showed no significant influence on extraction efficiency, due to the absorption property of the liquid extraction phase. Next, the limit of detection (LOD) was found, and the reproducibility of the developed cooled membrane gas sampling method was evaluated. Results showed that LODs with a membrane diameter of 19mm at room temperature sampling were 9.2ng/L, 0.12ng/L, 0.10ng/L for limonene, cinnamaldehyde and 2-pentadecanone, respectively. Intra- and inter-membrane sampling reproducibility revealed RSD% lower than 8% and 13%, respectively. Results uniformly demonstrated that the proposed cooled membrane device could serve as an alternative powerful tool for future gas sampling. PMID:24647099

Jiang, Ruifen; Pawliszyn, Janusz

2014-04-18

120

Photodetector having high speed and sensitivity  

SciTech Connect

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.

Morse, Jeffrey D. (Martinez, CA); Mariella, Jr., Raymond P. (Danville, CA)

1991-01-01

121

Photodetector having high speed and sensitivity  

SciTech Connect

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. 10 figs.

Morse, J.D.; Mariella, R.P. Jr.

1989-12-01

122

High Sensitivity Imprint Measurements on Nike Laser  

NASA Astrophysics Data System (ADS)

Hydrodynamic instability seeded by laser non-uniformity (laser imprint) is an important factor in performance of direct-drive ICF targets. Most of the imprint occurs during the initial low-intensity (``foot'') part of the pulse, necessary to compress the target to achieve high gain. Experiments are carried out on Nike KrF laser with induced spatial incoherence (ISI) smoothing. The amount of imprint is varied by changing the uniformity the foot of the pulse. The resulting Raleigh-Taylor (RT) amplified areal mass non-uniformity is measured by face-on x-ray radiography using Bragg reflection from a curved crystal coupled to an x-ray streak camera. The streak camera was recently retrofitted with a new high sensitivity CCD camera. The sensitivity of the CCD has enabled it to be fiberoptically coupled directly to the streak camera output, without an image intensifier and lens coupling. This gave an increased overall spatial resolution as well as lower noise. Because of the strong short wavelength component of RT amplified imprint, the increased resolution and lower noise resulted in much lower noise floor in the measurement. Experimental results are compared with 2D simulations using FAST hydrocode for a range of foot uniformities and intensities. Work supported by the U. S. DOE/NNSA.

Karasik, Max

2005-10-01

123

Photodetector having high speed and sensitivity  

SciTech Connect

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{minus}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{minus}x}Ga{sub x}As layer and the recombination layer. 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.

Morse, J.D.; Mariella, R.P. Jr.

1991-09-24

124

High-sensitivity detection of TNT  

PubMed Central

We report high-sensitivity detection of 2,4,6-trinitrotoluene (TNT) by using laser photoacoustic spectroscopy where the laser radiation is obtained from a continuous-wave room temperature high-power quantum cascade laser in an external grating cavity geometry. The external grating cavity quantum cascade laser is continuously tunable over ?400 nm around 7.3 ?m and produces a maximum continuous-wave power of ?200 mW. The IR spectroscopic signature of TNT is sufficiently different from that of nitroglycerine so that unambiguous detection of TNT without false positives from traces of nitroglycerine is possible. We also report the results of spectroscopy of acetylene in the 7.3-?m region to demonstrate continuous tunability of the IR source.

Pushkarsky, Michael B.; Dunayevskiy, Ilya G.; Prasanna, Manu; Tsekoun, Alexei G.; Go, Rowel; Patel, C. Kumar N.

2006-01-01

125

High speed curved position sensitive detector  

DOEpatents

A high speed curved position sensitive porportional counter detector for use in x-ray diffraction, the detection of 5-20 keV photons and the like. The detector employs a planar anode assembly of a plurality of parallel metallic wires. This anode assembly is supported between two cathode planes, with at least one of these cathode planes having a serpentine resistive path in the form of a meander having legs generally perpendicular to the anode wires. This meander is produced by special microelectronic fabrication techniques whereby the meander "wire" fans outwardly at the cathode ends to produce the curved aspect of the detector, and the legs of the meander are small in cross-section and very closely spaced whereby a spatial resolution of about 50 .mu.m can be achieved. All of the other performance characteristics are about as good or better than conventional position sensitive proportional counter type detectors. Count rates of up to 40,000 counts per second with 0.5 .mu.s shaping time constants are achieved.

Hendricks, Robert W. (Montgomery County, VA); Wilson, Jack W. (Knox County, TN)

1989-01-01

126

A high sensitive roll angle interferometer  

NASA Astrophysics Data System (ADS)

A roll angle interferometer with high sensitivity is designed in this paper. Two sets of centrosymmetric beams are used to travel through the measurement and reference arms of the roll angle interferometer which contains two specific optical devices: wedge prism assembly and wedge mirror assembly. The optical path change in both arms caused by roll is converted into phase shift which can be measured by interferometer. Because of the adoption of the centrosymmetric measurement structure, the straightness errors, yaw error and pitch error can be avoided and the dead path is minimized, so that the stability and the accuracy of the measurement can be greatly enhanced. The resolution for the roll measurement is about 0.006? with the measurement range of ±1°.

Le, Yanfen; Hou, Wenmei; Hu, Kai; Ju, Aisong

2013-01-01

127

High-sensitivity roll-angle interferometer.  

PubMed

A roll-angle interferometer with high sensitivity is presented in this Letter. Two sets of centrosymmetric beams are used to travel through the measurement and reference arms of the roll-angle interferometer, which contains two specific optical devices: wedge prism assembly and wedge mirror assembly. Changes of the optical path in the interferometric arms caused by roll are differential and converted into phase shift through a particular interferometer system. The interferometric beams are a completely common path for the adoption of the centrosymmetric measurement structure, and the cross talk of the straightness, yaw, and pitch errors is avoided. The dead path is minimized, so the stability and the accuracy of the measurement can be greatly enhanced. The experimental results fit well with the theoretical analysis, and a measurement resolution of sub-microradian is achieved experimentally. PMID:24104824

Le, Yanfen; Hou, Wenmei; Hu, Kai; Shi, Kai

2013-09-15

128

Demonstration of high sensitivity laser ranging system  

NASA Technical Reports Server (NTRS)

We report on a high sensitivity semiconductor laser ranging system developed for the Gravity and Magnetic Earth Surveyor (GAMES) for measuring variations in the planet's gravity field. The GAMES laser ranging instrument (LRI) consists of a pair of co-orbiting satellites, one which contains the laser transmitter and receiver and one with a passive retro-reflector mounted in an drag-stabilized housing. The LRI will range up to 200 km in space to the retro-reflector satellite. As the spacecraft pair pass over the spatial variations in the gravity field, they experience along-track accelerations which change their relative velocity. These time displaced velocity changes are sensed by the LRI with a resolution of 20-50 microns/sec. In addition, the pair may at any given time be drifting together or apart at a rate of up to 1 m/sec, introducing a Doppler shift into the ranging signals. An AlGaAs laser transmitter intensity modulated at 2 GHz and 10 MHz is used as fine and medium ranging channels. Range is measured by comparing phase difference between the transmit and received signals at each frequency. A separate laser modulated with a digital code, not reported in this paper, will be used for coarse ranging to unambiguously determine the distance up to 200 km.

Millar, Pamela S.; Christian, Kent D.; Field, Christopher T.

1994-01-01

129

A case of high noise sensitivity  

NASA Astrophysics Data System (ADS)

A case of noise sensitivity with a five-year follow-up period is reported. The patient was a 34-year-old single man who was diagnosed as having psychosomatic disorder triggered by two stressful life events in rapid succession with secondary hypersensitivity to noise. Hypersensitivity to light and cold also developed later in the clinical course. The auditory threshold was within the normal range. The discomfort threshold as a measure of the noise sensitivity secondary to mental illness was measured repeatedly using test tone of audiometry. The discomfort threshold varied depending upon his mental status, ranging from 40-50 dB in the comparatively poorer mental state to 70-95 dB in the relatively good mental state. The features of noise sensitivity, including that secondary to mental illness, are discussed.

Murata, M.; Sakamoto, H.

1995-10-01

130

A High Sensitivity MEMS Pressure Sensor  

Microsoft Academic Search

The piezoresistive effect in a van der Pauw (VDP) stress sensor subjected to biaxial stress was considered. The VDP resistance equations were combined with the silicon piezoresistivity equations to yield relations for the change in resistance of a VDP sensor in terms of the applied state of stress. Then the sensitivity of the VDP sensor to biaxial stress was determined

Jesse Law; Ahsan Mian

2007-01-01

131

High sensitivity optical fiber temperature sensor based on the temperature cross-sensitivity feature of RI-sensitive device  

NASA Astrophysics Data System (ADS)

Considerable part of optical fiber refractive index (RI) sensors suffer from the drawback of cross-sensitivity to temperature because of the thermo-optic effect of materials. In this paper, we propose a straightforward method to utilize the temperature cross-sensitivity feature of an optical fiber RI-sensitive device and thus got a high sensitivity temperature sensor. The sensor consists of a single mode fiber-multimode fiber core(MMFC)-single mode fiber structural refractometer encapsulated into a deionized water-filled cylindrical aluminum alloy shell. Benefiting from the larger thermo-optic coefficient difference between water and MMFC compared with the general cladding and core, the wavelength of transmitted spectrum presents enhanced shift when the ambient temperature change and thus get a higher temperature sensitivity. Experimental results show that the enhanced temperature sensitivity is about 358 pm/°C, which is almost 30 times that of the inherent temperature sensitivity.

Sun, Hao; Hu, Manli; Rong, Qiangzhou; Du, Yanying; Yang, Hangzhou; Qiao, Xueguang

2014-07-01

132

PASSIVE TERAHERTZ MICROSCOPY WITH A HIGHLY SENSITIVE DETECTOR  

Microsoft Academic Search

A passive terahertz (THz) microscope has been developed for sensitive imaging of spontaneous THz radiation. The THz microscope consisted mainly of a Ge objective lens, a confocal pinhole, Ge relay lenses, and a highly sensitive THz detector (Charge-Sensitive Infrared Phototransistor, CSIP). Then experimental examinations of the developed microscope were performed. First, THz signals, which were related to the spontaneous thermal

Yusuke Kajihara; Takeji Ueda; Patrick Nickels; Susumu Komiyama

2009-01-01

133

Effect of Pantex MAA Soil on High Explosive Sensitivity.  

National Technical Information Service (NTIS)

Grit is known to affect the impact and friction sensitivity of High Explosives (HE). This increase in sensitivity occurs due to localized hot spots which occur within the HE as a result of high-speed shear flow and resulting interactions between high melt...

D. N. Preston E. L. Roemer P. D. Peterson T. R. McClary

2011-01-01

134

Transplantation in the highly sensitized pediatric patient.  

PubMed

Sensitization against HLA antigens is a growing problem in the field of pediatric cardiac transplantation. Although surgical outcomes for congenital heart disease have improved over the decades, these successes have added to the growing list of sensitized patients who eventually may require transplantation.Cardiac transplantation survival has improved, but morbidity and mortality secondary to HLA antibodies hinder outcome. Aside from acute hemodynamic compromise, there is compelling evidence linking sensitization and AMR with the development of CAV, a major limiting factor affecting long-term graft survival. Clinical advances have improved our understanding of the roles of antibody type, CFAs and non-CFAs, and DSAs and non-DSAs. Therapeutic strategies target both the T- and B-cell lines. Combinations that include plasmapheresis, IVIG, cyclophosphamide, and rituximab have been used in clinical studies with variable success.Two newer agents show promise, targeting both ends of the antibody-mediated spectrum: Bortezomib depletes plasma cell populations, and eculizumab blocks the terminal effects of antibody action, thus preventing myocardial cell dysfunction and death. Despite numerous diagnostic and therapeutic advances, many questions remain about the best approaches.The role of HLA antibodies remains the central target of investigation. PMID:24891624

Castleberry, Chesney; Ryan, Thomas D; Chin, Clifford

2014-06-01

135

High sensitivity leak detection method and apparatus  

DOEpatents

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

Myneni, Ganapatic R. (Grafton, VA)

1994-01-01

136

High sensitivity leak detection method and apparatus  

DOEpatents

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

Myneni, G.R.

1994-09-06

137

Highly sensitive magnetite nano clusters for MR cell imaging  

PubMed Central

High sensitivity and suitable sizes are essential for magnetic iron oxide contrast agents for cell imaging. In this study, we have fabricated highly MR sensitive magnetite nanoclusters (MNCs) with tunable sizes. These clusters demonstrate high MR sensitivity. Especially, water suspensions of the MNCs with average size of 63 nm have transverse relaxivity as high as 630 s-1mM-1, which is among the most sensitive iron oxide contrast agents ever reported. Importantly, such MNCs have no adverse effects on cells (RAW 264.7). When used for cell imaging, they demonstrate much higher efficiency and sensitivity than those of SHU555A (Resovist), a commercially available contrast agent, both in vitro and in vivo, with detection limits of 3,000 and 10,000 labeled cells, respectively. The studied MNCs are sensitive for cell imaging and promising for MR cell tracking in clinics.

2012-01-01

138

Highly sensitive magnetite nano clusters for MR cell imaging  

NASA Astrophysics Data System (ADS)

High sensitivity and suitable sizes are essential for magnetic iron oxide contrast agents for cell imaging. In this study, we have fabricated highly MR sensitive magnetite nanoclusters (MNCs) with tunable sizes. These clusters demonstrate high MR sensitivity. Especially, water suspensions of the MNCs with average size of 63 nm have transverse relaxivity as high as 630 s-1mM-1, which is among the most sensitive iron oxide contrast agents ever reported. Importantly, such MNCs have no adverse effects on cells (RAW 264.7). When used for cell imaging, they demonstrate much higher efficiency and sensitivity than those of SHU555A (Resovist), a commercially available contrast agent, both in vitro and in vivo, with detection limits of 3,000 and 10,000 labeled cells, respectively. The studied MNCs are sensitive for cell imaging and promising for MR cell tracking in clinics.

Li, Mingli; Gu, Hongchen; Zhang, Chunfu

2012-03-01

139

High Sensitivity Organic Monolayers for Photonic Switching  

NASA Astrophysics Data System (ADS)

Chemisorbed monolayers containing chromophores have been used in the past for non-contact switching of liquid crystal devices. However, most of these systems have required large optical doses to develop the necessary anisotropic molecular orientation distribution. We used an aminoazobenzene (aAzb) material that is derived from methyl red to make self-assembled monolayers that become anisotropic under very small illumination levels of polarized blue light. A nematic liquid crystal (5CB) cell, with this monolayer on one window, requires only 5.5 mJ/cm2, or 1.8 absorbed photons per molecule, to reach 90 20-micron thickness of the device. This unprecedented sensitivity is due to rapid relaxation of the aAzb photoisomerization (enabling an effective Brownian ratchet process), a favorable in-plane orientation and non-aggregated nature of the aAzb groups, and an optimal surface density with uniform coverage of the monolayer.

Yi, Y. W.; Furtak, T. E.; Farrow, M. J.; Walba, D. M.; Fang, G.; Maclennan, J. E.; Clark, N. A.

2004-03-01

140

Fabrication of Sensitive High Tc Bolometers.  

National Technical Information Service (NTIS)

The rapid change of resistance with temperature of high quality films of high T sub c superconductors can be used to make resistance thermometers with very low temperature noise. Measurements on c-axis yttrium barium copper oxide (YBCO) films have given a...

M. Nahum S. Verghese Q. Hu P. L. Richards K. Char

1990-01-01

141

Highly sensitive chemical detection in the field  

SciTech Connect

Optical sensing methods, in particular infrared absorption spectroscopy combined with quantum cascade lasers (QCLs), are highly suited for the detection of chemicals since they enable rapid detection and are amenable for autonomous operation in a compact and rugged package.

Myers, Tanya L.; Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.

2010-11-10

142

A sensitive high resolution neutron imaging detector  

NASA Astrophysics Data System (ADS)

We present a two-step method for a high-resolution neutron area detector in which a metal foil with a high absorption cross section acts as a neutron to charged particle converter. After the foil is activated, the neutron field information is transferred from the converter foil to an imaging device by autoradiography. This two-step process using a storage photostimulable phosphor avoids interferences from non-neutron radiation found in the radiation field.

Cheng, Y. T.; Mildner, D. F. R.

2000-11-01

143

High sensitivity of SPR with microplasmonic structures  

NASA Astrophysics Data System (ADS)

The plasmonic nature of discontinuous thin films with micro-patterned structures such as triangles and hole arrays present distinct optical properties with a Kretschmann surface plasmon resonance (SPR) instrument. Au microstructures were prepared with a modified nanospheres lithography (NSL) method using 3.2 ?m spheres which gives 1.8 ?m triangles and hole arrays with hole diameter ranging from 2.5 to 0.5 ?m. The sensitivity to refractive index in thin film is increased by up to 45% with using microhole arrays instead of continuous film. A transition in the microstructure aspect from triangles to hole arrays with large hole diameter affects the spectral aspect of the SPR active band. Triangles present a characteristic broad transmission maximum band while in hole arrays, a broad and weak absorption band first appears for large holes, which sharpens and increases in intensity as the hole diameter decreases. Moreover, the SPR penetration depth is tuned between 230 and 30 nm as the microstructure aspect shifts from continuous film, to small hole arrays and to isolated triangles. Thus, these new plasmonic properties were observed in microhole arrays excited in Kretschmann SPR configuration, which are spectrally similar to continuous film. These can significantly improve the existing SPR sensing methods.

Live, Ludovic S.; Masson, Jean-Francois

2010-02-01

144

Validation of an ultra-high performance liquid chromatography tandem mass spectrometric method for quantifying uracil and 5,6-dihydrouracil in human plasma.  

PubMed

A simple, rapid, sensitive and specific ultra-high-performance liquid chromatography-tandem mass spectrometry method (Waters UPLC-MS-MS) is developed and validated for the quantification of uracil (U) and 5,6-dihydrouracil (UH2) levels in human plasma. Analytes are extracted using ethyl acetate and isopropanol after deproteination, and separated by high-performance liquid chromatography (HPLC) (Acquity UPLC BEH C18 column) in a binary mobile phase system under gradient elution conditions at a flow rate of 0.4 mL/min. 5-Bromo-uracil (UBr) is used as the internal standard. The detection is performed on a triple-quadrupole mass spectrometer via electrospray positive ionization. Multiple reaction monitoring mode using the transitions m/z 112.82 ? 70.05, m/z 114.88 ? 55.04 and m/z 190.83 ? 117.86 is used to quantify U, UH2 and UBr, respectively. The method is linear in the concentration range of 0.625-160.0 ng/mL. The total run time is 4.5 min per injection. Nine-point calibration curve and four-points quality controls are used. Excellent linearity and precision are observed with correlation coefficient (r(2)) > 0.9999. The intra-batch and inter-batch precisions are ? 7.3% and ? 8.6%, and accuracy is ? 17%. The developed method is shown to be suitable for routine quantitative determination of U, UH2 and 5,6-dihydrouracil-to-uracil ratio in clinical practice. PMID:22689904

Coudoré, François; Roche, Denis; Lefeuvre, Sandrine; Faussot, Delphine; Billaud, Eliane M; Loriot, Marie-Anne; Beaune, Philippe

2012-01-01

145

Environmental dosimetry using high-sensitivity TL detectors  

NASA Astrophysics Data System (ADS)

Two highly sensitive thermoluminescent (TL) materials (Al 2O 3:C and CaSO 4:Tm) were investigated for environmental monitoring. We compared their response to low and to high linear energy transfer (LET) radiations in order to develop a two-element TL system. The relative TL efficiency for ?-particle irradiation as compared to ?-exposure was about 0.04 and 0.5 for Al 2O 3:C and CaSO 4:Tm, respectively. Measurements of external environmental radiation doses in an international balloon experiment were performed with our highly-sensitive TL system having various sensitivities to low and to high LET radiations.

Katona, T.; Osvay, M.; Deme, S.; Kovács, A.

2007-08-01

146

Rate Sensitivity of High Strength Syntactic Foam.  

National Technical Information Service (NTIS)

A series of dynamic experiments was performed on high crush strength syntactic foam to characterize how rate affects the compressive and tensile properties of the material. The Investigation was carried out as part of a larger effort to develop a rate sen...

R. Doleski S. Plunkett W. Tucker

2003-01-01

147

Novel high-sensitivity fluorescence polarization reader  

NASA Astrophysics Data System (ADS)

We have developed a new fluorescence polarization (FP) reader suitable for high-throughput screening (HST) and ultra-HTS whose assay-performance and sample-throughput are both considerably improved over present state-of-the-art instrumentation. The SymmetryTM reader possesses a number of features that differ from conventional HTS FP readers. These include: laser-based excitation, liquid crystal polarization optics that rapidly and accurately measure polarization states; and CCD detectors to capture emission from multiple wells. We show that the performance in assays relevant to the drug discovery process, such as G- protein coupled receptor-based assays, is significantly enhanced due to a dramatic improvement in precision. Furthermore, the CCD-detection system used can substantially improve sample throughput compared to sequential readers while maintaining high performance.

Hoyt, Clifford C.; Levenson, Richard M.; Banks, Peter

2001-05-01

148

Triggers for a high sensitivity charm experiment  

SciTech Connect

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.

Christian, D.C.

1994-07-01

149

A high sensitivity z-axis torsional silicon accelerometer  

Microsoft Academic Search

This paper presents a high sensitivity silicon micromachined capacitive accelerometer fabricated using a three mask, dissolved wafer process. High electrical sensitivity is obtained by using high aspect-ratio comb fingers with narrow air gaps of 2 ?m and large overlap area of 12 ?m×300 ?m. Torsional suspension beams 150 ?m long with a cross-sectional area of 12 ?m×3 ?m are used

Arjun Selvakumar; Farrokh Ayazi; Khalil Najafi

1996-01-01

150

Chemoreceptor sensitivity and maladaptation to high altitude in man  

Microsoft Academic Search

Summary  Studies were carried out to find out the role of chemoreceptor sensitivity in the causation of maladaptation syndromes on acute exposure to altitude. The experiments were done in two phases. In phase I, the responses in chemoreceptor sensitivity were studied in altitude acclimatized subjects and compared with those who suffered from either High Altitude Pulmonary Oedema (HAPO) or Acute Mountain

L. Mathew; P. M. Gopinathan; S. S. Purkayastha; J. Sen Gupta; H. S. Nayar

1983-01-01

151

Miniaturized superconducting quantum interference magnetometers for high sensitivity applications  

Microsoft Academic Search

A miniaturized niobium based dc superconducting quantum interference device (SQUID) magnetometer for high magnetic field sensitivity applications has been developed. The sensing coil consists of an integrated square superconducting coil with a length of 3 mm, involving a device area much smaller with respect to the standard SQUID magnetometers with a comparable magnetic field sensitivity; so it allows increasing the

C. Granata; A. Vettoliere; M. Russo

2007-01-01

152

High sensitive tellurium based NO 2 gas sensor  

Microsoft Academic Search

For the first time it is shown, that tellurium based thin films exhibit high sensitivity to nitrogen dioxide at room temperature. The resistance of the tellurium films decreases reversibly in the presence of NO2. The sensitivity of this device depends on the gas concentration and it increases to lower concentrations less than 3ppm. The response time is considerably short and

D. Tsiulyanu; S. Marian; V. Miron; H.-D. Liess

2001-01-01

153

Fabrication of sensitive high Tc bolometers  

NASA Technical Reports Server (NTRS)

The rapid change of resistance with temperature of high quality films of high T sub c superconductors can be used to make resistance thermometers with very low temperature noise. Measurements on c-axis yttrium barium copper oxide (YBCO) films have given a spectral intensity of temperature noise less than 4 times 10(exp -8) K/Hz(exp 1/2) at 10 Hz. Consequently, the opportunity exists to make useful bolometric infrared detectors that operate near 90 K which can be cooled with liquid nitrogen. The fabrication and measurement of two bolometer architectures are discussed. The first is a conventional bolometer which consists of a 3000 A thick YBCO film deposited in situ by laser ablation on top of a 500 A thick SrTiO3 thickness and diced into 1x1 mm(exp 2) bolometer chips. Gold black smoke was used as the radiation absorber. The voltage noise was less than the amplifier noise when the film was current biased. Optical measurements gave an NEP of 5 times 10(exp -11) W/Hz(exp 1/2) at 10 Hz. The second architecture is that of an antenna-coupled microbolometer which consists of a small (5x10 cubic microns) YBCO film deposited directly on a bulk substrate with a low thermal conductance (YSZ) and an impedance matched planar lithographed spiral or log-periodic antenna. This structure is produced by standard photolithographic techniques. Measurements gave an electrical NEP of 4.7 times 10(exp -12) W/Hz(exp 1/2) at 10 kHz. Measurements of the optical efficiency are in progress. The measured performance of both bolometers will be compared to other detectors operating at or above liquid nitrogen temperatures so as to identify potential applications.

Nahum, Michael; Verghese, S.; Hu, Qing; Richards, Paul L.; Char, K.; Newman, N.; Sachtjen, Scott A.

1990-01-01

154

Stability of the proteasome inhibitor bortezomib in cell based assays determined by ultra-high performance liquid chromatography coupled to tandem mass spectrometry.  

PubMed

Bortezomib represents the first clinically approved proteasome inhibitor for multiple myeloma. Research conducted on its intracellular kinetics in target cells and on possibly related mechanisms of resistance is sparse so far. We therefore developed and validated a highly sensitive ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC/MS/MS) method for bortezomib quantification within cultured myeloma cells and media. Fast gradient UPLC based on a BEH C18 column (1.7?m particle size) with aqueous formic acid and acetonitrile as mobile phase. Selective extraction procedures using protein precipitation extraction (PPE) and liquid-liquid extraction (LLE) were established and compared. Extracted bortezomib was quantified by positive electrospray tandem mass spectrometry using deuterated D8-bortezomib as internal standard. The calibrated ranges were 0.5-2500pg per sample. For LLE, overall accuracies varied between 99.2% and 112% (medium) and 89.9% and 111% (cells), while overall precision ranged from 1.13% to 13.0% (medium) and 2.80% to 12.7% (cells), respectively. Recovery rates (cells/medium) were >77%/>65% for LLE and >89%/63% for PPE. Matrix effects were generally lower for LLE compared to PPE. Regardless of the extraction method, retrievable amounts of bortezomib were considerably reduced after 24h of incubation (0.2, 1, 5, and 25nM). Revealing greater dependence on the extent of acidification, retrieval of bortezomib can be increased distinctly in acidified solution or acidified culture medium. Thus, particular attention needs to be paid to the occurring bortezomib degradation in neutral culture medium since correct quantification of intracellular bortezomib can only be achieved in relation to the corresponding extracellular concentration. PMID:24780258

Clemens, Jannick; Longo, Magdalena; Seckinger, Anja; Hose, Dirk; Haefeli, Walter Emil; Weiss, Johanna; Burhenne, Jürgen

2014-06-01

155

Multipurpose High Sensitivity Radiation Detector: Terradex  

NASA Astrophysics Data System (ADS)

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 222Rn 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 222Rn 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.

Alpat, Behcet; Aisa, Damiano; Bizzarri, Marco; Blasko, Sandor; Esposito, Gennaro; Farnesini, Lucio; Fiori, Emmanuel; Papi, Andrea; Postolache, Vasile; Renzi, Francesca; Ionica, Romeo; Manolescu, Florentina; Ozkorucuklu, Suat; Denizli, Haluk; Tapan, Ilhan; Pilicer, Ercan; Egidi, Felice; Moretti, Cesare; Dicola, Luca

2007-05-01

156

Frequency Selective Surfaces for High-Sensitivity Terahertz Sensors  

Microsoft Academic Search

We present a frequency selective surface (FSS) of asymmetric split-ring resonators for terahertz (THz) sensor applications. Multiple resonances of the rings combine to sharp edges in the FSS's frequency response to achieve high sensitivity.

Christian Debus; Peter Haring Bolivar

2007-01-01

157

Polymer microfiber rings for high-sensitivity optical humidity sensing.  

PubMed

We demonstrate microrings assembled with polyacrylamide (PAM) microfibers for high-sensitivity relative humidity (RH) sensing. When exposed to moisture, the PAM microfiber absorbs water molecules and inflates monotonically with the increasing humidity, resulting in evident spectral shifts of the resonance peaks of the microring. By measuring the spectral shifts, the microring shows sensitivity as high as 490 pm/%RH and a response time of about 120 ms, within a dynamic range from 5% to 71% RH. PMID:22086051

Wang, Pan; Gu, Fuxing; Zhang, Lei; Tong, Limin

2011-11-01

158

Stacked piezoelectret microphones of simple design and high sensitivity  

Microsoft Academic Search

Pressure-chamber and free-field measurements of high sensitivity piezoelectret microphones of two different designs are reported. High sensitivity is achieved by (1) an increase of the piezoelectric d33 -coefficient of the cellular polypropylene films by a pressure expansion procedure and (2) stacking of the films. The pressure expansion results in large d33-coefficients of up to 600 pC\\/N in the audio frequency

J. Hillenbrand; G. M. Sessler

2006-01-01

159

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

NASA Astrophysics Data System (ADS)

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.

Niu, Zhe; Zhao, Yulong; Tian, Bian

2014-01-01

160

Highly efficient light-harvesting ruthenium sensitizer for thin-film dye-sensitized solar cells.  

PubMed

A high molar extinction coefficient heteroleptic ruthenium complex, incorporating an electron-rich hexylthio-terminal chain, has been synthesized and demonstrated as an efficient sensitizer for dye-sensitized solar cells. With this new sensitizer excellent power conversion efficiency is 11.5% and 4.7% obtained under an irradiation of full sunlight (air mass 1.5 global) in combination with a volatility electrolyte and solid state hole transporting material, respectively. The devices with low volatility electrolyte showed good stability under visible-light soaking at 60 degrees C during 1000 h of accelerated tests. PMID:19746929

Chen, Chia-Yuan; Wang, Mingkui; Li, Jheng-Ying; Pootrakulchote, Nuttapol; Alibabaei, Leila; Ngoc-le, Cevey-Ha; Decoppet, Jean-David; Tsai, Jia-Hung; Grätzel, Carole; Wu, Chun-Guey; Zakeeruddin, Shaik M; Grätzel, Michael

2009-10-27

161

Infrared spectroscopic imaging with high spatial resolution and high sensitivity  

Microsoft Academic Search

Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) is a very sensitive imaging technique for the characterization of molecular films. In order to achieve a spatial resolution close to the diffraction limit a very small pinhole which acts as a point-source has to be used. However, such a small pinhole, the typical diameter would be app. 100 mum, may reduces dramatically

Valdas Sablinskas; Gerald Steiner; Justinas Ceponkus; Reiner Salzer

2008-01-01

162

Sensitivity of FMCW 95GHz cloud radar for high clouds  

Microsoft Academic Search

Studying the vertical structure of cloud is essential to make better atmospheric modellings for simulations of the global warming. Cloud observation requires very high sensitivity for radar. Although pulse radar is the mainstream of MMCR (millimeter wave cloud radar), FMCW radar has some advantages. FMCW signal has high spatial and time resolution, and enables high durability and cost-performance because all

J. Yamaguchi; T. Takano; T. Nakajima; T. Takamura; H. K. Y. Ohno; Y. Nakanishi; K. Akita; Y. Kawamura; H. A. Futaba; S. Yokote

2006-01-01

163

A high-sensitivity, position-sensitive fission chamber for subcriticality measurements of spent fuel  

NASA Astrophysics Data System (ADS)

A high-sensitivity fission counter has been developed for subcriticality measurements by the 252Cf-source-driven neutron noise analysis method which requires two neutron counter channels. Performance specifications were provided by ORNL for spent light water reactor (LWR) fuel configurations where multiplication factors ( k-values) could be as low as 0.85. A 3 × 3 array of 2 in. diameter, 8 ft long counters, fits into storage rack positions occupied by LWR fuel elements. Each counter consists of eight sensitive sections that contain a total of ˜18 g of 235U. Transmission-line technology is used to minimize capacitances and thus provides broad bandwidths. Each event in the fission counter produces two current pulses propagating in opposite directions on the transmission line. The differences in arrival times of the pulses at the ends of a counter determine the positions of the fission events. Tests on two fission counters show that each counter has a sensitivity of 12.5 cps/nv th and a position sensitivity with 1 ft resolution. Detection efficiency estimates for spent LWR fuel configurations indicate that, using two fission counters, subcriticality measurements can be made down to a k-value of 0.80: for two 3 × 3 counter arrays, to a k-value of 0.65. The 3 × 3 counter array or a single counter can be used in applications other than subcriticality measurements where position sensitivity, high sensitivity, and operability in high gamma fields are performance requirements.

Williams, J. A.; Mihalczo, J. T.; Ricker, C. W.; Glesius, F. L.; Kniss, T. A.

1990-12-01

164

Fabrication of High Sensitivity Carbon Microcoil Pressure Sensors  

PubMed Central

This work demonstrates a highly sensitive pressure sensor that was fabricated using carbon microcoils (CMCs) and polydimethylsiloxane (PDMS). CMCs were grown by chemical vapor deposition using various ratios of Fe-Sn catalytic solution. The pressure sensor has a sandwiched structure, in which the as-grown CMCs were inserted between two PDMS layers. The pressure sensor exhibits piezo-resistivity changes in response to mechanical loading using a load cell system. The yields of the growth of CMCs at a catalyst proportion of Fe:Sn = 95:5 reach 95%. Experimental results show that the sensor achieves a high sensitivity of 0.93%/kPa from the CMC yield of 95%. The sensitivity of the pressure sensor increases with increasing yield of CMCs. The demonstrated pressure sensor shows the advantage of high sensitivity and is suitable for mass production.

Su, Chih-Chung; Li, Chen-Hung; Chang, Neng-Kai; Gao, Feng; Chang, Shuo-Hung

2012-01-01

165

High sensitivity optomechanical reference accelerometer over 10 kHz  

NASA Astrophysics Data System (ADS)

We present an optically detected mechanical accelerometer that achieves a sensitivity of 100 ngn/?Hz over a bandwidth of 10 kHz and is traceable. We have incorporated a Fabry-Pérot fiber-optic micro-cavity that is currently capable of measuring the test-mass displacement with sensitivities of 200 am/?Hz , and whose length determination enables traceability to the International System of Units. The compact size and high mQ-product achieved combined with the high sensitivity and simplicity of the implemented optical detection scheme highlight our device and this category of accelerometers, outlining a path for high sensitivity reference acceleration measurements and observations in seismology and gravimetry.

Guzmán Cervantes, Felipe; Kumanchik, Lee; Pratt, Jon; Taylor, Jacob M.

2014-06-01

166

Highly sensitive wide bandwidth photodetectors using chemical vapor deposited graphene  

NASA Astrophysics Data System (ADS)

A photodetector generating a nearly constant photocurrent in a very wide spectral range from ultraviolet (UV) to infrared has been demonstrated using chemical vapor deposited (CVD) graphene. Instability due to a photochemical reaction in the UV region has been minimized using an Al2O3 passivation layer, and a responsivity comparable to that of Highly Ordered Pyrolytic Graphite graphene photodetectors of ˜8 mA/W has been achieved at a 0.1 V bias, despite high defect density in the CVD graphene. A highly sensitive multi-band photodetector using graphene has many potential applications including optical interconnects, multi-band imaging sensors, highly sensitive motion detectors, etc.

Goo Kang, Chang; Kyung Lee, Sang; Jin Yoo, Tae; Park, Woojin; Jung, Ukjin; Ahn, Jinho; Hun Lee, Byoung

2014-04-01

167

High-sensitivity three-mode optomechanical transducer  

NASA Astrophysics Data System (ADS)

Three-mode optomechanical interactions have been predicted to allow the creation of very high sensitivity transducers in which very strong optical self-cooling and strong optomechanical quantum entanglement are predicted. Strong coupling is achieved by engineering a transducer in which both the pump laser and a single signal sideband frequency are resonantly enhanced. Here we demonstrate that very high sensitivity can be achieved in a very simple system consisting of a Fabry-Perot cavity with CO2 laser thermal tuning. We demonstrate a displacement sensitivity of ˜1×10-17m/Hz, which is sufficient to observe a thermally excited acoustic mode in a 5.6 kg sapphire mirror with a signal-to-noise ratio of more than 20 dB. It is shown that a measurement sensitivity of ˜2×10-20m/Hz limited by the quantum shot noise is achievable with optimization of the cavity parameters.

Zhao, C.; Fang, Q.; Susmithan, S.; Miao, H.; Ju, L.; Fan, Y.; Blair, D.; Hosken, D. J.; Munch, J.; Veitch, P. J.; Slagmolen, B. J. J.

2011-12-01

168

Design of a charge sensitive preamplifier on high resistivity silicon  

Microsoft Academic Search

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the

V. Radeka; P. Rehak; S. Rescia; E. Gatti; A. Longoni; M. Sampietro; P. Holl; L. Struder; J. Kemmer

1988-01-01

169

Design of a charge sensitive preamplifier on high resistivity silicon  

Microsoft Academic Search

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the

V. Radeka; P. Rehak; S. Rescia; E. Gatti; A. Longoni; M. Sampietro; P. Holl; L. Strueder; J. Kemmer

1987-01-01

170

Highly sensitive suspended-gate ion sensitive transistor for the detection of pH  

NASA Astrophysics Data System (ADS)

This paper presents a new device for the pH detection. It is based on a suspended polysilicon gate field effect transistor (SGFET). The sensitive layer is made of silicon nitride as for ISFET technology. The suspended bridge, used as gate electrode, is formed with doped polysilicon covered with silicon nitride layers for electrical insulation. The layers are deposited by Low Pressure Chemical Vapor Deposition (LPCVD). Surface micro-technology allows to obtain a small height (0.5?m) suspended-bridge. In this case, the solution penetrates under the gate. The high field effect in the gap between the gate and the channel is enough to change the charges distribution. Very high pH sensitivity, greater than 200 mV/pH, is found with this new structure and it is much higher than the usual Nernstian sensitivity of ISFETs. The device concept, electrical characteristics, and the effect of the thickness of the gap between the bridge and the sensitive layer on the pH sensitivity are discussed in this study.

Bendriaa, F.; Le Bihan, F.; Salaun, A. C.; Mohammed-Brahim, T.; Bonnaud, O.

2005-07-01

171

Highly sensitive optical microresonator sensors for photoacoustic imaging  

NASA Astrophysics Data System (ADS)

We present novel concave Fabry Perot (FP) sensor arrays for photoacoustic imaging which were fabricated using a high-precision inkjet printing approach to produce the cavity and employed physical vapor deposition to form the dielectric mirrors. Our concave FP cavity design provides excellent beam confinement within the cavity enabling high finesse and thus high sensitivity to be achieved. Two such concave sensors are evaluated in terms of their sensitivity and acoustic bandwidth. A 66 ?m thick concave sensor is shown to provide a noise equivalent pressure (NEP) of 85 Pa and an acoustic bandwidth of 16 MHz, and can potentially be used as a sensitive broadband sensor for superficial imaging. A 250 ?m thick sensor with an NEP of 12 Pa and acoustic bandwidth of 4 MHz was also developed for deep tissue imaging applications.

Li, Jing; Taylor, Alaric; Papakonstantinou, Ioannis; Zhang, Edward; Beard, Paul

2014-03-01

172

High-resist sensitization by pattern and flood combination lithography  

NASA Astrophysics Data System (ADS)

In EUV lithography (EUVL), the most critical issue has been low intensity of the EUV light source. Light-source intensity and resist sensitivity have a complementary relationship. Therefore, the sensitization of EUV resist is very important to compensate the low intensity of the EUV light source. However, dramatically improving the resist sensitivity of chemically amplified resist (CAR) is very difficult because of the resolution/line-width roughness/sensitivity (RLS) trade-off. Therefore, we propose a very new process: high resist sensitization by the combination lithography of EUV or EB pattern exposure with UV flood exposure (PF combination lithography) of photosensitized chemically amplified resist (PS-CAR). The combination lithography of EB pattern exposure with UV flood exposure achieved a sensitivity enhancement of more than a factor of 10 with respect to conventional EB single-exposure lithography, without loss in space resolution of line/space of 75 nm1. The breakthrough of RLS trade-off by PF combination lithography of PS-CAR is explained based on RLS trade-off simulation method2 and acid generation mechanism of PF combination lithography of PS-CAR. One of the problems of the PF combination lithography of PS-CAR is postexposure delay (PED) effects suffered from airborne contamination. The present paper describes forming of 75 nm contact hole and PED effects in the PF combination lithography of PS-CAR. The sensitization of EUV resists by new method accelerates EUVL implementation.

Tagawa, Seiichi; Oshima, Akihiro; Enomoto, Satoshi; Dinh, C. Q.

2014-04-01

173

Infrared frequency combs and supercontinua for multiplex high sensitivity spectroscopy  

PubMed Central

An infrared high-brightness light source based on supercontinuum generation through a SF6 photonic crystal fiber seeded by a Cr4+:YAG femtosecond oscillator is developed for high resolution multiplex spectroscopy in the 1.5 ?m region. Moreover, a multiplex high resolution approach based on a Cr4+:YAG frequency comb enables to probe large spectral domains, with simultaneous sensitive measurement of the absorption and the dispersion associated with all individual spectral features.

Mandon, J.; Sorokin, E.; Sorokina, I.T; Guelachvili, G.; Picque, N.

2010-01-01

174

Analytical Glycobiology at High Sensitivity: Current Approaches and Directions  

PubMed Central

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

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

2013-01-01

175

Low frequency/high sensitivity horizontal monolithic sensor  

NASA Astrophysics Data System (ADS)

This paper describes a new mechanical implementation of a folded pendulum based inertial sensor, configurable as seismometer and as accelerometer.1 The sensor is compact, light, scalable, tunable (< 100mHz), with large band (10-6 Hz÷10Hz), high quality factor (Q < 1500 in air) instrument and good immunity to environmental noises, guaranteed by an integrated laser optical readout. The measured sensitivity curve is in very good agreement with the theoretical one (10-12 m/ ? Hz in the band (0.1 ÷ 10Hz). Typical applications are in the field of earthquake engineering, geophysics, and in all applications requiring large band-low frequency performances coupled with high sensitivities.

Acernese, F.; Canonico, R.; De Rosa, R.; Giordano, G.; Romano, R.; Barone, F.

2012-10-01

176

High-sensitivity cardiac troponins in everyday clinical practice  

PubMed Central

High-sensitivity cardiac troponin (hs-cTn) assays are increasingly being used in many countries worldwide, however, a generally accepted definition of high-sensitivity is still pending. These assays enable cTn measurement with a high degree of analytical sensitivity with a low analytical imprecision at the low measuring range of cTn assays (coefficient of variation of < 10% at the 99th percentile upper reference limit). One of the most important advantages of these new assays is that they allow novel, more rapid approaches to rule in or rule out acute coronary syndromes (ACSs) than with previous cTn assay generations which are still more commonly used in practice worldwide. hs-cTn is also more sensitive for the detection of myocardial damage unrelated to acute myocardial ischemia. Therefore, the increase in early diagnostic sensitivity of hs-cTn assays for ACS comes at the cost of a reduced ACS specificity, because more patients with other causes of acute or chronic myocardial injury without overt myocardial ischemia are detected than with previous cTn assays. As hs-cTn assays are increasingly being adopted in clinical practice and more hs-cTn assays are being developed, this review attempts to synthesize the available clinical data to make recommendations for their everyday clinical routine use.

Mair, Johannes

2014-01-01

177

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

PubMed

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 excited state. Novel unsymmetrical zinc phthalocyanine sensitizers with "push" and "pull" groups have made it possible to reduce the aggregation on a TiO(2) surface, tune the level of the excited state, and strengthen the electronic coupling between the phthalocyanine core and the TiO(2) surface. As a result, the power conversion efficiency of up to 3.5% has been achieved. Perylenes are well-known as chemically, thermally, and photophysically stable dyes and have been used in various optical devices and applications. Nevertheless, the power conversion efficiency remained low compared to other organic dyes. The origin of such limited cell performance is the poor electron-donating abilities of the perylenes, which makes it difficult to inject electrons from the excited singlet state of the perylenes to the conduction band of the TiO(2) electrode efficiently. Strongly electron-donating perylene carboxylic acid derivatives with amine substituents at their perylene core have allowed us to increase the power conversion efficiency of up to approximately 7% in perylene-sensitized solar cells. The efficiency of large pi-aromatic molecule-sensitized solar cells could be improved significantly if the dyes with larger red and near-infrared absorption could be developed. PMID:19408942

Imahori, Hiroshi; Umeyama, Tomokazu; Ito, Seigo

2009-11-17

178

A high sensitivity nanomaterial based SAW humidity sensor  

NASA Astrophysics Data System (ADS)

In this paper, a highly sensitive humidity sensor is reported. The humidity sensor is configured by a 128°YX-LiNbO3 based surface acoustic wave (SAW) resonator whose operating frequency is at 145 MHz. A dual delay line configuration is realized to eliminate external temperature fluctuations. Moreover, for nanostructured materials possessing high surface-to-volume ratio, large penetration depth and fast charge diffusion rate, camphor sulfonic acid doped polyaniline (PANI) nanofibres are synthesized by the interfacial polymerization method and further deposited on the SAW resonator as selective coating to enhance sensitivity. The humidity sensor is used to measure various relative humidities in the range 5-90% at room temperature. Results show that the PANI nanofibre based SAW humidity sensor exhibits excellent sensitivity and short-term repeatability.

Wu, Tsung-Tsong; Chen, Yung-Yu; Chou, Tai-Hsu

2008-04-01

179

High-grade breast cancers include both highly sensitive and highly resistant subsets to cytotoxic chemotherapy  

Microsoft Academic Search

Purpose  We reported that breast cancers achieving pathological complete response (pCR) or progressive disease (PD) to neoadjuvant\\u000a chemotherapy (NAC), which are considered exact opposites on the chemosensitivity spectrum, have certain clinicopathological\\u000a features in common. To determine the highly sensitive and highly resistant subsets to cytotoxic chemotherapy, we evaluated\\u000a predictive factors for pCR and PD to NAC, and assessed the similarities in

Tomo Osako; Rie Horii; Masaaki Matsuura; Kaoru Domoto; Yoshimi Ide; Yumi Miyagi; Shunji Takahashi; Yoshinori Ito; Takuji Iwase; Futoshi Akiyama

2010-01-01

180

HIGHLY SENSITIVE BIOASSAYS FOR EVALUATING AIRBORNE MUTAGENS INDOORS  

EPA Science Inventory

The standard mutagenicity bioassays that are readily applied to the valuation of outdoor air samples collected by high volume samplers are not efficiently sensitive to measure the mutagenicity of low volume air samples collected indoors. wo microsuspension mutation assays using v...

181

A Low Noise High Gain Bandwidth Charge Sensitive Preamplifier  

Microsoft Academic Search

The concept of the charge sensitive amplifier is discussed and a novel method for obtaining a high gain amplifier stage through the use of a positive current feedback dynamic plate load is described. It is shown that under certain conditions this type of feedback can provide increased bandwidth as well as increased low frequency gain. The schematic of a preamplifier

Jack Hahn; Ralph Mayer

1962-01-01

182

High Sensitivity MEMS Strain Sensor: Design and Simulation  

Microsoft Academic Search

In this article, we report on the new design of a m iniaturized strain microsensor. The proposed sensor utilizes the piezoresistive pro perties of doped single crystal silicon. Employing the Micro Electro Mechanical Systems (MEMS) technology, high sensor sensitivities and resolutions have been achieved. T he current sensor design employs different levels of signal amplifications. These am plifications include geometric,

Ahmed A. S. Mohammed; Walied A. Moussa; Edmond Lou

2008-01-01

183

Towards low-cost, high-sensitivity, integrated biosensors  

Microsoft Academic Search

The early detection of pathogens in a solution sample using a biosensor and associated electronics manufactured in a mainstream semiconductor process is currently attracting much research and development interests around the globe. This is primarily because such a system will be low-cost, easily manufactured, and can offer very high sensitivities, thus potentially stopping the rapid spread of diseases due to

M. J. Deen; M. W. Shinwari; P. R. Selvaganapathy

2008-01-01

184

High throughput modular chambers for rapid evaluation of anesthetic sensitivity  

Microsoft Academic Search

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

Yi Sun; Jingqiu Chen; Gregory Pruckmayr; James E Baumgardner; David M Eckmann; Roderic G Eckenhoff; Max B Kelz

2006-01-01

185

A high sensitivity inductive sensor for blade tip clearance measurement  

NASA Astrophysics Data System (ADS)

A multiplexed inductive sensor consisting of multiple mini-sized planar spiral coils for detecting multiple tip clearances of rotor blades is presented. The sensor measures the tip clearances by monitoring the inductance changes of planar spiral coils caused by the passage of the rotor blades. A resonance frequency division multiplexing technique and parallel LC resonance measurement were applied to the multiple sensor coils, making it feasible to measure multiple tip clearances using only one set of measurement electronics with high sensitivity and resolution. The results from tests conducted on a bench-top test rig have demonstrated that the sensor is capable of simultaneously measuring multiple tip clearances from 0 to 5 mm with a 10 ?m resolution at a high rotary speed up to 80?000 RPM. With its high resolution, high sensitivity and capability of monitoring a large number of tip clearances simultaneously, this sensor can potentially be used for advanced active tip clearance control in turbine machinery.

Du, Li; Zhu, Xiaoliang; Zhe, Jiang

2014-06-01

186

High Sensitivity Mass Spectrometer for Noble Gas Analysis  

Microsoft Academic Search

A high-sensitivity mass spectrometer for noble gas analysis is described in detail. Ultra-high vacuum techniques have been used throughout so that small rare gas samples can be closed off within the spectrometer envelope and analyzed statically. This procedure is of considerable advantage in analyzing argon and lighter rare gases. The background spectrum when the spectrometer pressure is 5×1010 mm Hg

John H. Reynolds

1956-01-01

187

High-sensitivity linear piezoresistive transduction for nanomechanical beam resonators.  

PubMed

Highly sensitive conversion of motion into readable electrical signals is a crucial and challenging issue for nanomechanical resonators. Efficient transduction is particularly difficult to realize in devices of low dimensionality, such as beam resonators based on carbon nanotubes or silicon nanowires, where mechanical vibrations combine very high frequencies with miniscule amplitudes. Here we describe an enhanced piezoresistive transduction mechanism based on the asymmetry of the beam shape at rest. We show that this mechanism enables highly sensitive linear detection of the vibration of low-resistivity silicon beams without the need of exceptionally large piezoresistive coefficients. The general application of this effect is demonstrated by detecting multiple-order modes of silicon nanowire resonators made by either top-down or bottom-up fabrication methods. These results reveal a promising approach for practical applications of the simplest mechanical resonators, facilitating its manufacturability by very large-scale integration technologies. PMID:25000256

Sansa, Marc; Fernández-Regúlez, Marta; Llobet, Jordi; San Paulo, Alvaro; Pérez-Murano, Francesc

2014-01-01

188

High-sensitivity EUV resists based on fluorinated polymers  

NASA Astrophysics Data System (ADS)

There is a growing interest in the fluorinization of resist materials in improving pattern formation efficiency for extreme ultraviolet (EUV) lithography. The increased polymer absorption coefficient obtained through this resist platform is expected to enhance acid production and in effect improve pattern formation efficiency. Our work over the past several years has shown that the main-chain fluorinated base resins realized by the co-polymerization of tetrafluoroethylene (TFE) and norbornene derivatives offer high dissolution rates. Based on this, a EUV resist which was prepared using the by the fluorinated polymers was investigated. Imaging evaluations, using the small field exposure tool (SFET by Canon / EUVA) with annular (?outer 0.7 / ?inner 0.3) illumination conditions were performed. Relatively high sensitivity of 6.3mJ•cm-2 for half-pitch (hp) 45nm and satisfactory resolution limit of hp 40nm was achieved. At present, line width roughness (LWR) was measured at comparatively large values of more than 8.4nm at hp 45nm. This shows that further material and process optimizations may be necessary to improve its present lithographic capability. However, these initial results have shown the potential of fluorinated-polymer based platform as a possible solution for high sensitivity, high resolution and low LWR EUV resists. In this paper, we report recent results of high sensitivity of 5.1mJ•cm-2 for half-pitch (hp) 40nm, optimization of protecting groups and photo acid generators

Yamashita, Tsuneo; Morita, Masamichi; Tanaka, Yoshito; Santillan, Julius Joseph; Itani, Toshiro

2011-03-01

189

Highly efficient photocathodes for dye-sensitized tandem solar cells.  

PubMed

Thin-film dye-sensitized solar cells (DSCs) based on mesoporous semiconductor electrodes are low-cost alternatives to conventional silicon devices. High-efficiency DSCs typically operate as photoanodes (n-DSCs), where photocurrents result from dye-sensitized electron injection into n-type semiconductors. Dye-sensitized photocathodes (p-DSCs) operate in an inverse mode, where dye-excitation is followed by rapid electron transfer from a p-type semiconductor to the dye (dye-sensitized hole injection). Such p-DSCs and n-DSCs can be combined to construct tandem solar cells (pn-DSCs) with a theoretical efficiency limitation well beyond that of single-junction DSCs (ref. 4). Nevertheless, the efficiencies of such tandem pn-DSCs have so far been hampered by the poor performance of the available p-DSCs (refs 3, 5-15). Here we show for the first time that p-DSCs can convert absorbed photons to electrons with yields of up to 96%, resulting in a sevenfold increase in energy conversion efficiency compared with previously reported photocathodes. The donor-acceptor dyes, studied as photocathodic sensitizers, comprise a variable-length oligothiophene bridge, which provides control over the spatial separation of the photogenerated charge carriers. As a result, charge recombination is decelerated by several orders of magnitude and tandem pn-DSCs can be constructed that exceed the efficiency of their individual components. PMID:19946281

Nattestad, A; Mozer, A J; Fischer, M K R; Cheng, Y-B; Mishra, A; Bäuerle, P; Bach, U

2010-01-01

190

High-sensitivity three-mode optomechanical transducer  

SciTech Connect

Three-mode optomechanical interactions have been predicted to allow the creation of very high sensitivity transducers in which very strong optical self-cooling and strong optomechanical quantum entanglement are predicted. Strong coupling is achieved by engineering a transducer in which both the pump laser and a single signal sideband frequency are resonantly enhanced. Here we demonstrate that very high sensitivity can be achieved in a very simple system consisting of a Fabry-Perot cavity with CO{sub 2} laser thermal tuning. We demonstrate a displacement sensitivity of {approx}1x10{sup -17} m/{radical}(Hz), which is sufficient to observe a thermally excited acoustic mode in a 5.6 kg sapphire mirror with a signal-to-noise ratio of more than 20 dB. It is shown that a measurement sensitivity of {approx}2x10{sup -20} m/{radical}(Hz) limited by the quantum shot noise is achievable with optimization of the cavity parameters.

Zhao, C.; Fang, Q.; Susmithan, S.; Miao, H.; Ju, L.; Fan, Y.; Blair, D.; Hosken, D. J.; Munch, J.; Veitch, P. J.; Slagmolen, B. J. J. [School of Physics, University of Western Australia, 35 Stirling Highway, Nedlands, Western Australia, 6009 (Australia); Department of Physics, University of Adelaide, Adelaide, South Australia, 5005 (Australia); Centre for Gravitational Physics, Australian National University, Canberra, 0200 (Australia)

2011-12-15

191

Quantum dots as FRET acceptors for highly sensitive multiplexing immunoassays  

NASA Astrophysics Data System (ADS)

Homogeneous immunoassays have the benefit that they do not require any time-consuming separation steps. FRET is one of the most sensitive homogeneous methods used for immunoassays. Due to their extremely strong absorption over a broad wavelength range the use of quantum dots as FRET acceptors allows for large Foerster radii, an important advantage for assays in the 5 to 10 nm distance range. Moreover, because of their size-tunable emission, quantum dots of different sizes can be used with a single donor for the detection of different analytes (multiplexing). As the use of organic dyes with short fluorescence decay times as donors is known to be inefficient with quantum dot acceptors, lanthanide complexes with long luminescence decays are very efficient alternatives. In this contribution we present the application of commercially available biocompatible CdSe/ZnS core/shell quantum dots as multiplexing FRET acceptors together with a single terbium complex as donor in a homogeneous immunoassay system. Foerster radii of 10 nm and FRET efficiencies of 75 % are demonstrated. The high sensitivity of the terbium-toquantum dot FRET assay is shown by sub-100-femtomolar detection limits for two different quantum dots (emitting at 605 and 655 nm) within the same biotin-streptavidin assay. Direct comparison to the FRET immunoassay "gold standard" (FRET from Eu-TBP to APC) yields a three orders of magnitude sensitivity improvement, demonstrating the big advantages of quantum dots not only for multiplexing but also for highly sensitive nanoscale analysis.

Geissler, Daniel; Hildebrandt, Niko; Charbonnière, Loïc J.; Ziessel, Raymond F.; Löhmannsröben, Hans-Gerd

2009-02-01

192

Highly Sensitive Porous Silicon Membrane Waveguide Sensor Using UltraHigh Order Mode  

Microsoft Academic Search

This work proposes a label-free porous silicon membrane waveguide biosensor with very high sensitivity due to the utilization of an ultra-high order mode for sensing. Its sensitivity toward refractive index perturbation is simulated and shown to be superior to that of a porous silicon membrane waveguide utilizing a low order mode. The proposed sensor structure is especially suitable for biosensing

Guoguang Rong

2009-01-01

193

High molar extinction coefficient organic sensitizers for efficient dye-sensitized solar cells.  

PubMed

We have designed and synthesized highly efficient organic sensitizers with a planar thienothiophene-vinylene-thienothiophene linker. Under standard global AM 1.5 solar conditions, the JK-113-sensitized cell gave a short circuit photocurrent density (J(sc)) of 17.61 mA cm(-2), an open-circuit voltage (V(oc)) of 0.71 V, and a fill factor (FF) of 72%, corresponding to an overall conversion efficiency (eta) of 9.1%. The incident monochromatic photo-to-current conversion efficiency (IPCE) of JK-113 exceeds 80% over the spectral region from 400 to 640 nm, reaching its maximum of 93% at 475 nm. The band tails off toward 770 nm, contributing to the broad spectral light harvesting. Solar-cell devices based on the sensitizer JK-113 in conjunction with a volatile electrolyte and a solvent-free ionic liquid electrolyte gave high conversion efficiencies of 9.1% and 7.9%, respectively. The JK-113-based solar cell fabricated using a solvent-free ionic liquid electrolyte showed excellent stability under light soaking at 60 degrees C for 1000 h. PMID:19998435

Choi, Hyunbong; Raabe, Ines; Kim, Duckhyun; Teocoli, Francesca; Kim, Chulwoo; Song, Kihyung; Yum, Jun-Ho; Ko, Jaejung; Nazeeruddin, Md K; Grätzel, Michael

2010-01-25

194

A UPLC-MS Method for the Determination of Ofloxacin Concentrations in Aqueous Humor  

PubMed Central

A rapid, simple, and specific method based on ultra performance liquid chromatography (UPLC) with mass spectrometry detection has been developed for quantitative analysis of ofloxacin in human aqueous humor using tobramycin as internal standard (IS). Chromatographic separation was achieved on a Waters Acquity UPLC BEH C18 Shield column (150 × 2.1 mm, 1.7 ?m) eluted with 95:5 water: acetonitrile (v/v) containing 0.1% formic acid and a flow rate of 0.3 mL/minute. The total analysis time was three minutes with ofloxacin eluting at 1.67 ± 0.03 minutes. The linearity of the method ranged from 0.1 to 8 ?g/mL with r2 = 0.998. The method was validated according to FDA guidelines with respect to linearity, accuracy, precision, specificity, and stability. The limits of detection and quantification were 0.03 and 0.10 ?g/mL, respectively. The developed method was successfully applied to the analysis of samples that have been obtained from patients.

Plotas, Panagiotis; Anastasopoulos, Charalampos; Makri, Olga E; Leotsinidis, Michalis; Georgakopoulos, Constantine D

2014-01-01

195

Sensitive and high sensitivity next generation cardiac troponin assays: more than just a name.  

PubMed

In the 20 years that cardiac troponin testing has been available in clinical laboratories, the biomarker has revolutionised testing of patients with acute coronary syndromes. Cardiac troponin I and T testing has become the cornerstone for diagnosis of myocardial infarction and is useful for risk assessment and management of suspected acute coronary syndrome patients. As evidence and knowledge have evolved, it has become clear that even small troponin elevations are associated with adverse health outcomes. As a result there have been several generations of troponin assays, all toward tests that reliably detect lower concentrations of this critical analyte. Guidance for cardiac troponin interpretation has been in the form of myocardial infarction redefinition and evidence-based clinical and analytical guidelines. Although terminology naming generations for cardiac troponin assays has been inconsistent, state-of-the-art cardiac troponin assays are generally referred to as 'sensitive' assays and are in general compliance with analytical guidelines. Evidence shows that use of a sensitive troponin assay can result in diagnosis of myocardial infarction earlier. Next generation cardiac troponin I and T assays will likely be termed 'high sensitivity'; these assays should have the ability to measure troponin with a CV of total error of <10% at concentrations significantly lower than the 99 percentile of the normal reference population. As such, these assays should reliably measure troponin in most normal individuals and detect troponin changes (delta values) below the 99 percentile. This property may result in earlier ACS diagnosis and better management. Utilisation of high sensitivity troponin measurements may be useful for applications other than acute coronary syndromes including risk stratifying patients with renal insufficiency, heart failure, cardiac amyloid and screening elderly patients. PMID:21436630

Christenson, Robert H; Phillips, Daniel

2011-04-01

196

Quantum-Dot-Sensitized Solar Cell with Unprecedentedly High Photocurrent  

PubMed Central

The reported photocurrent density (JSC) of PbS quantum dot (QD)-sensitized solar cell was less than 19 mA/cm2 despite the capability to generate 38?mA/cm2, which results from inefficient electron injection and fast charge recombination. Here, we report on a PbS:Hg QD-sensitized solar cell with an unprecedentedly high JSC of 30?mA/cm2. By Hg2+ doping into PbS, JSC is almost doubled with improved stability. Femtosecond transient study confirms that the improved JSC is due to enhanced electron injection and suppressed charge recombination. EXAFS reveals that Pb-S bond is reinforced and structural disorder is reduced by interstitially incorporated Hg2+, which is responsible for the enhanced electron injection, suppressed recombination and stability. Thanks to the extremely high JSC, power conversion efficiency of 5.6% is demonstrated at one sun illumination.

Lee, Jin-Wook; Son, Dae-Yong; Ahn, Tae Kyu; Shin, Hee-Won; Kim, In Young; Hwang, Seong-Ju; Ko, Min Jae; Sul, Soohwan; Han, Hyouksoo; Park, Nam-Gyu

2013-01-01

197

Low frequency/high sensitivity horizontal monolithic sensor  

NASA Astrophysics Data System (ADS)

This paper describes a new mechanical implementation of a folded pendulum based inertial sensor, configurable as seismometer and as accelerometer.1 The sensor is compact, light, scalable, tunable (< 100mHz), with large band (10-6 Hz÷10Hz), high quality factor (Q > 1500 in air) instrument and good immunity to environmental noises, guaranteed by an integrated laser optical readout. The measured sensitivity curve is in very good agreement with the theoretical one (10-12 m/?Hz in the band (0.1 ÷ 10Hz). Typical applications are in the field of earthquake engineering, geophysics, and in all applications requiring large band-low frequency performances coupled with high sensitivities.

Acernese, F.; De Rosa, R.; Giordano, G.; Romano, R.; Barone, F.

2012-03-01

198

Quantum-Dot-Sensitized Solar Cell with Unprecedentedly High Photocurrent  

NASA Astrophysics Data System (ADS)

The reported photocurrent density (JSC) of PbS quantum dot (QD)-sensitized solar cell was less than 19 mA/cm2 despite the capability to generate 38 mA/cm2, which results from inefficient electron injection and fast charge recombination. Here, we report on a PbS:Hg QD-sensitized solar cell with an unprecedentedly high JSC of 30 mA/cm2. By Hg2+ doping into PbS, JSC is almost doubled with improved stability. Femtosecond transient study confirms that the improved JSC is due to enhanced electron injection and suppressed charge recombination. EXAFS reveals that Pb-S bond is reinforced and structural disorder is reduced by interstitially incorporated Hg2+, which is responsible for the enhanced electron injection, suppressed recombination and stability. Thanks to the extremely high JSC, power conversion efficiency of 5.6% is demonstrated at one sun illumination.

Lee, Jin-Wook; Son, Dae-Yong; Ahn, Tae Kyu; Shin, Hee-Won; Kim, In Young; Hwang, Seong-Ju; Ko, Min Jae; Sul, Soohwan; Han, Hyouksoo; Park, Nam-Gyu

2013-01-01

199

Very low frequency/high sensitivity triaxial monolithic inertial sensor  

NASA Astrophysics Data System (ADS)

This paper describes a new mechanical implementation of a triaxial sensor, configurable as seismometer and/or as accelerometer, consisting of three one-dimensional monolithic FP sensors, suitably geometrically positioned. The triaxial sensor is, therefore, compact, light, scalable, tunable instrument (frequency < 100mHz), with large band (10-7 Hz - 10Hz), high quality factor (Q > 2500 in air) with good immunity to environmental noises, guaranteed by an integrated laser optical readout. The measured sensitivity curve is in very good agreement with the theoretical ones (10-12m/?Hz) in the band (0.1 ÷ 10Hz). Typical applications are in the field of earthquake engineering, geophysics, civil engineering and in all applications requiring large band-low frequency performances coupled with high sensitivities.

Acernese, F.; De Rosa, R.; Giordano, G.; Romano, R.; Barone, F.

2014-03-01

200

Highly sensitive strain sensors based on magnetic tunneling junctions  

Microsoft Academic Search

Micrometer-sized highly sensitive strain sensors are presented. The sensors are based on magnetic tunneling junctions (MTJs) incorporating magnetostrictive free layers. The influence of mechanical strain upon the free layer is explained by a model taking into account the total free energy of the sensing layer. Those MTJ devices prepared in situ with magnetostrictive Fe50Co50 layers exhibit a tunneling magnetoresistance (TMR)

M. Lohndorf; T. Duenas; M. Tewes; E. Quandt; M. Ruhrig; J. Wecker

2002-01-01

201

Low Temperature High Sensitivity Temperature Compensated Heat Flux Sensor  

Microsoft Academic Search

Miniature (0.74×0.71×0.14 cm thick) heat flux transducers were designed and constructed to measure heat transfer by conduction, convection, radiation, or almost any combination of these from 75 to 300 K. A high sensitivity, approximately constant at 250 mV?(W?cm2), was obtained by utilizing the semiconductor silver-antimony-telluride. Temperature compensation was achieved by matching the changing properties of the insulating material to the

E. H. Schulte; R. F. Kohl

1969-01-01

202

High sensitivity fringe projection micro-shape measurement system  

Microsoft Academic Search

The high sensitivity fringe projection automated system for shape measurement of the object with P-V ranging from 10 - 2000 micrometers is presented. The system uses the carrier-frequency phase-shifting fringe pattern analysis method which enables the proper shape determination on the basis of a single image. The system may be applied for the object with max. dimension up to 20

Maria Pirga; Malgorzata Kujawinska

1994-01-01

203

Hi-net: High sensitivity seismograph network, Japan  

Microsoft Academic Search

The high sensitivity seismograph network in Japan (Hi-net), composed of around 600 seismic stations, is a part of the project\\u000a made by ‘The Headquarter for Earthquake Research Promotion’ after 1995 Hyogoken-nanbu Earthquake and has been constructed\\u000a and operated by National Research Institute for Earth Science and Disaster Prevention (NIED). Seismic stations are distributed\\u000a homogeneously covering whole Japan Islands with an

Kazushige Obara

2003-01-01

204

Structural Glycomic Analyses at High Sensitivity: A Decade of Progress  

NASA Astrophysics Data System (ADS)

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.

Alley, William R.; Novotny, Milos V.

2013-06-01

205

Allergen microarrays on high-sensitivity silicon slides  

Microsoft Academic Search

We have recently introduced a silicon substrate for high-sensitivity microarrays, coated with a functional polymer named copoly(DMA-NAS-MAPS).\\u000a The silicon dioxide thickness has been optimized to produce a fluorescence intensification due to the optical constructive\\u000a interference between the incident and reflected lights of the fluorescent radiation. The polymeric coating efficiently suppresses\\u000a aspecific interaction, making the low background a distinctive feature of

Marina Cretich; Daniela Breda; Francesco Damin; Marta Borghi; Laura Sola; Selim M. Unlu; Samuele E. Burastero; Marcella Chiari

2010-01-01

206

Horizontal film balance having wide range and high sensitivity  

DOEpatents

A thin-film, horizontal balance instrument is provided for measuring surface tension (surface energy) of thin films suspended on a liquid substrate. The balance includes a support bearing and an optical feedback arrangement for wide-range, high sensitivity measurements. The force on the instrument is balanced by an electromagnet, the current through the magnet providing a measure of the force applied to the instrument. A novel float construction is also disclosed. 5 figs.

Abraham, B.M.; Miyano, K.; Ketterson, J.B.

1983-11-08

207

Horizontal film balance having wide range and high sensitivity  

DOEpatents

A thin-film, horizontal balance instrument is provided for measuring surface tension (surface energy) of thin films suspended on a liquid substrate. The balance includes a support bearing and an optical feedback arrangement for wide-range, high sensitivity measurements. The force on the instrument is balanced by an electromagnet, the current through the magnet providing a measure of the force applied to the instrument. A novel float construction is also disclosed.

Abraham, B.M.; Miyano, K.; Ketterson, J.B.

1981-03-05

208

Structural Glycomic Analyses at High Sensitivity: A Decade of Progress  

PubMed Central

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.

Alley, William R.; Novotny, Milos V.

2014-01-01

209

High efficiency neutron sensitive amorphous silicon pixel detectors  

SciTech Connect

A multi-layer a-Si:H based thermal neutron detector was designed, fabricated and simulated by Monte Carlo method. The detector consists of two PECVD deposited a-Si:H pin detectors interfaced with coated layers of Gd, as a thermal neutron converter. Simulation results indicate that a detector consisting of 2 Gd films with thicknesses of 2 and 4 {mu}m, sandwiched properly with two layers of sufficiently thick ({approximately}30{mu}m) amorphous silicon diodes, has the optimum parameters. The detectors have an intrinsic efficiency of about 42% at a threshold setting of 7000 electrons, with an expected average signal size of {approximately}12000 electrons which is well above the noise. This efficiency will be further increased to nearly 63%, if we use Gd with 50% enrichment in {sup 157}Gd. We can fabricate position sensitive detectors with spatial resolution of 300 {mu}m with gamma sensitivity of {approximately}1 {times} 10{sup {minus}5}. These detectors are highly radiation resistant and are good candidates for use in various application, where high efficiency, high resolution, gamma insensitive position sensitive neutron detectors are needed.

Mireshghi, A.; Cho, G.; Drewery, J.S.; Hong, W.S.; Jing, T.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V.

1993-11-01

210

High sensitive FBG pressure sensor using metal bellows  

NASA Astrophysics Data System (ADS)

A fiber-optic sensor scheme, capable of the simultaneous measurement of pressure and temperature using two in-line Fiber Bragg Gratings (FBGs) is reported. Sensor head is configured by embedding the two FBGs with metal bellows, such that FBG1 is sensitive to both pressure and temperature, whereas FBG2 is only sensitive to temperature. High pressure sensitivity is achieved because of the lower spring rate in longitudinal direction to that of the large elastic modulus in transverse direction of the metal bellows. Pressure and temperature measurement is made by monitoring the shift of Bragg wavelengths of the FBGs corresponds to variation in pressure and temperature. From the test results, the obtained pressure and temperature sensitivities are 86 pm/psi and 9.17 pm/°C, over a dynamic range of 0-40 psi pressure, and 25-110°C temperature measurements respectively. The experimental results well agreed with the theoretical results and show good linearity. This simple design, economical and all fiber optic sensors can be used for liquid and gas pressure measurements, and under-water applications.

Vengal Rao, P.; Srimannarayana, K.; Sai Shankar, M.; Kishore, P.

2013-09-01

211

High sensitive volumetric imaging of renal microcirculation in vivo using ultrahigh sensitive optical microangiography  

NASA Astrophysics Data System (ADS)

We present a non-invasive, label-free imaging technique called Ultrahigh Sensitive Optical Microangiography (UHSOMAG) for high sensitive volumetric imaging of renal microcirculation. The UHS-OMAG imaging system is based on spectral domain optical coherence tomography (SD-OCT), which uses a 47000 A-line scan rate CCD camera to perform an imaging speed of 150 frames per second that takes only ~7 seconds to acquire a 3D image. The technique, capable of measuring slow blood flow down to 4 um/s, is sensitive enough to image capillary networks, such as peritubular capillaries and glomerulus within renal cortex. We show superior performance of UHS-OMAG in providing depthresolved volumetric images of rich renal microcirculation. We monitored the dynamics of renal microvasculature during renal ischemia and reperfusion. Obvious reduction of renal microvascular density due to renal ischemia was visualized and quantitatively analyzed. This technique can be helpful for the assessment of chronic kidney disease (CKD) which relates to abnormal microvasculature.

Zhi, Zhongwei; Jung, Yeongri; Jia, Yali; An, Lin; Wang, Ruikang K.

2011-02-01

212

Highly sensitive imaging of renal microcirculation in vivo using ultrahigh sensitive optical microangiography.  

PubMed

Studying renal microcirculation and its dynamics is of great importance for understanding the renal function and further aiding the diagnosis, prevention and treatment of renal pathologies. In this paper, we present a potentially useful method to provide high-sensitive volumetric imaging of renal microcirculations using ultrahigh-sensitive optical microangiography (UHS-OMAG). The UHS-OMAG image system used here is based on spectral domain optical coherence tomography, which uses a broadband light source centered at 1300 nm with an imaging speed of 150 frames per second that requires ~6.7 sec to complete one 3D scan of ~2.5 × 2.5 mm(2) area. The technique is sensitive enough to image capillary networks, such as peritubular capillaries within renal cortex. We show the ability of UHS-OMAG to provide depth-resolved volumetric images of capillary level renal microcirculation. We also show that UHS-OMAG is capable of monitoring the changes of renal microcirculation in response to renal ischemia and reperfusion. Finally, we attempt to show the capability of OMAG to provide quantitative analysis about velocity changes in a single capillary vessel (down to tens of microns per second) in response to the ischemic event. PMID:21559119

Zhi, Zhongwei; Jung, Yeongri; Jia, Yali; An, Lin; Wang, Ruikang K

2011-01-01

213

High-sensitive scanning laser magneto-optical imaging system  

SciTech Connect

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 3.47x10{sup -5} rad/{mu}m Oe shows a magnetic sensitivity of about 5 {mu}T, 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{sub 2}Cu{sub 3}O{sub 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.

Murakami, Hironaru; Tonouchi, Masayoshi [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2010-01-15

214

High-sensitive scanning laser magneto-optical imaging system.  

PubMed

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. PMID:20113101

Murakami, Hironaru; Tonouchi, Masayoshi

2010-01-01

215

A high-sensitivity small animal SPECT system  

NASA Astrophysics Data System (ADS)

Medical imaging using single gamma-ray-emitting radionuclides typically makes use of parallel hole collimators or pinholes in order to achieve good spatial resolution. However, a tradeoff in sensitivity is inherent in the use of a collimator, and modern preclinical single photon emission computed tomography (SPECT) systems detect a very small fraction of emitted gamma rays, often less than 0.1%. A system for small animal SPECT imaging which uses no collimators could potentially achieve very high sensitivity—several tens of percent—with reasonably sized detectors. This would allow two significant improvements in preclinical studies: images could be obtained more rapidly, allowing higher throughput for screening applications, or for dynamic processes to be observed with very good time resolution; and images could be obtained with less radioactive tracer, making possible the in vivo imaging of low-capacity receptor systems, aiding research into new tracer compounds, and reducing the cost and easing the regulatory burden of an experiment. Of course, a system with no collimator will not be able to approach the submillimeter spatial resolutions produced by the most advanced pinhole and collimated systems, but a high-sensitivity system with resolution of order 1 cm could nonetheless find significant and new use in the many molecular imaging applications which do not require good spatial resolution—for example, screening applications for drug development or new imaging agents. Rather than as an alternative to high-resolution SPECT systems, the high-sensitivity system is proposed as a radiotracer alternative to optical imaging for small animals. We have developed a prototype system for mouse imaging applications. The scanner consists of two large, thin, closely spaced scintillation detectors. Simulation studies indicate that a FWHM spatial resolution of 7 mm is possible. In an in vivo mouse imaging study using the 99mTc labeled tracer MAG-3, the sensitivity of the system is measured to be 40%. Simple projection images created by analytically combining the two detectors' data show sufficient resolution to observe the dynamic distribution of the radiotracer in the mouse.

Mitchell, Gregory S.; Cherry, Simon R.

2009-03-01

216

High derivatives for fast sensitivity analysis in linear magnetodynamics  

SciTech Connect

In this article, the authors present a method of sensitivity analysis using high derivatives and Taylor development. The principle is to find a polynomial approximation of the finite elements solution towards the sensitivity parameters. While presenting the method, they explain why this method is applicable with special parameters only. They applied it on a magnetodynamic problem, simple enough to be able to find the analytical solution with a formal calculus tool. They then present the implementation and the good results obtained with the polynomial, first by comparing the derivatives themselves, then by comparing the approximate solution with the theoretical one. After this validation, the authors present results on a real 2D application and they underline the possibilities of reuse in other fields of physics.

Petin, P. [ENSIEG, Saint Martin d`Heres (France). Lab. d`Electrotechnique de Grenoble] [ENSIEG, Saint Martin d`Heres (France). Lab. d`Electrotechnique de Grenoble; [FRMASOFT+CSI, Lyon (France); Coulomb, J.L. [ENSIEG, Saint Martin d`Heres (France). Lab. d`Electrotechnique de Grenoble] [ENSIEG, Saint Martin d`Heres (France). Lab. d`Electrotechnique de Grenoble; Conraux, P. [FRAMASOFT+CSI, Lyon (France)] [FRAMASOFT+CSI, Lyon (France)

1997-03-01

217

Highly Sensitive Measurements of 222Rn Diffusion and Emanation  

NASA Astrophysics Data System (ADS)

Highly sensitive techniques for determination of the 222Rn emanation from solids and diffusion through different membranes are presented. 222Rn and its daughters are measured via the alpha decays in special proportional counters at the absolute sensitivity of ~30 ?Bq. Radon diffusion can be measured at the level of ~10-13 cm2/s. Several samples were examined, e.g. stainless steel, teflon, various gaskets (emanation and diffusion measurements) and tanks. A combination of measurements of the 222Rn diffusion and emanation of thin nylon foils (used in the Borexino experiment) allowed the determination of 226Ra in the materials of interest at the level of ~10-12 g/g 238U-equivalent.

Zuzel, Grzegorz

2005-09-01

218

Sensitivity to Error Fields in NSTX High Beta Plasmas  

SciTech Connect

It was found that error field threshold decreases for high ? in NSTX, although the density correlation in conventional threshold scaling implies the threshold would increase since higher ? plasmas in our study have higher plasma density. This greater sensitivity to error field in higher ? plasmas is due to error field amplification by plasmas. When the effect of amplification is included with ideal plasma response calculations, the conventional density correlation can be restored and threshold scaling becomes more consistent with low ? plasmas. However, it was also found that the threshold can be significantly changed depending on plasma rotation. When plasma rotation was reduced by non-resonant magnetic braking, the further increase of sensitivity to error field was observed.

Jong-Kyu Park, Jonathan E. Menard, Stefan P. Gerhardt, Richard J. Buttery, Steve A. Sabbagh, Ronald E. Bell and Benoit P. LeBlanc

2011-11-07

219

FRET-Enabled Optical modulation for High Sensitivity Fluorescence Imaging  

PubMed Central

Fluorescence resonance energy transfer is utilized to engineer donor photophysics for facile signal amplification and selective fluorescence recovery from high background. This is generalized such that many different fluorophores can be used in optical modulation schemes to drastically improve fluorescence imaging sensitivity. Dynamic, simultaneous, direct excitation of the acceptor brightens and optically modulates higher energy donor emission. The externally-imposed modulation waveform enables selective donor fluorescence extraction through demodulation. By incorporating an acceptor with significant, spectrally-shifted, dark state population, necessary excitation intensities are quite low and agree well with simulated enhancements. Enhancement vs. modulation frequency directly yields dark state lifetimes in a simple ensemble measurement. Using the long-lived Cy5 dark state in conjunction with Cy3 donors, we demonstrate image extraction from a large background to yield ?10-fold sensitivity improvements through Synchronously Amplified Fluorescence Image Recovery (SAFIRe).

Richards, Chris I.; Hsiang, Jung-Cheng; Khalil, Andrew M.; Hull, Nathan P.; Dickson, Robert M.

2010-01-01

220

High sensitivity tests of the standard model for electroweak interactions  

SciTech Connect

The work done on this project was focussed mainly on LAMPF experiment E969 known as the MEGA experiment, a high sensitivity search for the lepton family number violating decay {mu} {yields} e{gamma} to a sensitivity which, measured in terms of the branching ratio, BR = ({mu}{yields}e{gamma})/({mu}{yields}e {nu}{sub {mu}} {nu}{sub e}) {approx}10{sup {minus}13} is over two orders of magnitude better than previously reported values. The work done on MEGA during this period was divided between that done at Valparaiso University and that done at LAMPF. In addition, some contributions were made to a proposal to the LAMPF PAC to perform a precision measurement of the Michel {rho} parameter, described below.

Koetke, D.D.

1992-01-01

221

Highly Sensitive Measurements of 222Rn Diffusion and Emanation  

SciTech Connect

Highly sensitive techniques for determination of the 222Rn emanation from solids and diffusion through different membranes are presented. 222Rn and its daughters are measured via the alpha decays in special proportional counters at the absolute sensitivity of {approx}30 {mu}Bq. Radon diffusion can be measured at the level of {approx}10-13 cm2/s. Several samples were examined, e.g. stainless steel, teflon, various gaskets (emanation and diffusion measurements) and tanks. A combination of measurements of the 222Rn diffusion and emanation of thin nylon foils (used in the Borexino experiment) allowed the determination of 226Ra in the materials of interest at the level of {approx}10-12 g/g 238U-equivalent.

Zuzel, Grzegorz [Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg (Germany)

2005-09-08

222

Development of highly sensitive monolithic interferometer for infrared planet search  

NASA Astrophysics Data System (ADS)

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 ?m. 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.

Wang, J.; Ge, J.; Wan, X.; Jiang, P.; Lee, B.

2011-07-01

223

Ultra wideband, high sensitivity magneto-optic field sensor  

NASA Astrophysics Data System (ADS)

Using the bismuth rare-earth iron garnet thick films we have demonstrated a magneto-optic (MO) field sensor. The sensor made of all dielectric materials is nearly noninvasive, and is operated at room temperature. The sensor's sensitivity is scalable; the same sensor design can be used for a low-field sensor to measure fields below nano-Tesla or for a high-field sensor to measure several hundred Tesla. The highest sensitivity that we have achieved with the sensor is about 30 pico-Tesla/(Hz)^1/2. Presently its frequency range is limited from DC to 2 GHz. We have carried out several different experiments with this sensor to explore a few interesting applications, such as electromagnetic signal interception tests over a very broad frequency range. In this presentation we will report our experimental results obtained from this MO field sensor.

Wu, Dong Ho; Garzarella, Anthony; Fratello, Vince

2012-02-01

224

High Sensitivity MEMS Strain Sensor: Design and Simulation  

PubMed Central

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/??), high absolute resolution (1??) and low power consumption (100?A) with a maximum range of ±4000?? has been reported. These performance characteristics have been achieved with high signal stability over a wide temperature range (±50°C), 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.

Mohammed, Ahmed A. S.; Moussa, Walied A.; Lou, Edmond

2008-01-01

225

High-sensitivity converters of a TV type  

NASA Astrophysics Data System (ADS)

Three principles of building high sensitive (low-level) converters of a TV-type are well known. They are based on the following: (1) usage of electron-optical image converters (IC) as input image amplifiers and its converting into a TV signal by commercial TV cameras (Fig. 1a); (2) location in a single vacuum volume of a receiving input part of IC with a diode silicon substrate -- a storage target -- in which a photoelectric image is being amplified (amplification factor is 100 . . . 300) and then is read out by an electron beam with the energy corresponding with the condition (sigma) less than 1 ((sigma) -- secondary electron emission coefficient). The converter developed on the base of this principal has got the name of superkremnikon (a super silicon-imaging device) (Fig. 1b); (3) location in a single vacuum volume of a receiving part of IC, amplification microchannel plate (MCP) with amplification factor 100 . . . 1000 and a CCD with amplification equal to 100 (Fig. 1c). One should take into account the following disadvantages of the above-mentioned devices of a TV-type: (1) not high linear resolution of an input image, caused by multiple conversion of an input image - - (2.2 . . . 3.5)(DOT)102 lines in the middle of a target; (2) inadequately high sensitivity, defined basically by optical losses. Limiting sensitivity within the visible range has been realized at superkremnikon (10-7 lx) coupled with an input IC through fiber-optical communication; (4) high cost of the converters, which is limiting their wide practical application for the purposes of medical diagnostics and non- destructive control. The alternative principle of building the high sensitive converters of a TV-type, based on a new method of energy radiation image conversion within a wide spectral range into an electrical (including TV) signal is proposed. In the frames of the new method the MCP is operating at the same time as a receiver, an amplifier and a two-sided storage target on reading out. A conventional image of the converter is given.

Venediktov, M. D.; Krutyakov, Yu. A.; Plotnikov, M. I.

1999-06-01

226

Position sensitive detection of neutrons in high radiation background field.  

PubMed

We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high ? and e(-) radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 ?m(2)) spectroscopic Timepix detector adapted for neutron detection utilizing very thin (10)B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10(-4). PMID:24517756

Vavrik, D; Jakubek, J; Pospisil, S; Vacik, J

2014-01-01

227

Piezoelectric rubber films for highly sensitive impact measurement  

NASA Astrophysics Data System (ADS)

We have successfully demonstrated the microfabrication of piezoelectric rubber films and their application in impact measurement. To realize the desired piezoelectricity and stretchability, cellular polydimethylsiloxane (PDMS) structures with micrometer-sized voids are internally implanted with bipolar charges, which function as dipoles and respond promptly to electromechanical stimuli. In the prototype demonstration, 300 µm thick cellular PDMS films are fabricated and internally coated with a thin polytetrafluoroethylene (PTFE) layer to secure the implanted charges. Meanwhile, the top and bottom surfaces of the cellular PDMS films are deposited with stretchable gold electrodes. An electric field up to 35 MV m-1 is applied across the gold electrodes to ionize the air in the voids and to implant charges on the inner surfaces. The resulting composite structures behave like rubber (with an elastic modulus of about 300 kPa) and show strong piezoelectricity (with a piezoelectric coefficient d33 higher than 1000 pC N-1). While integrated with a wide bandwidth and large dynamic-range charge amplifier, highly sensitive impact measurement (with a stress sensitivity of about 10 mV Pa-1) is demonstrated. As such, the demonstrated piezoelectric rubber films could potentially serve as a sensitive electromechanical material for low-frequency stimuli, and fulfill the needs of a variety of physiological monitoring and wearable electronics applications.

Wang, Jhih-Jhe; Tsai, Jui-Wei; Su, Yu-Chuan

2013-07-01

228

Development of high sensitivity pressure sensor using reduced clad FBG  

NASA Astrophysics Data System (ADS)

This study focused on the development of high sensitivity pressure sensor based on reduced clad FBG encapsulated in a stainless steel cylinder, partially filled with silicon rubber. The sensor works by means of transferring radial or lateral pressure into an axially stretched- strain along the length of the FBG. The experiment is carried out using two different FBG's have core/clad diameters of 9/125?m (FBG1) and 4/80?m (FBG2). FBG2 is chemically etched to reduce the cladding diameter which significantly enhances the pressure sensitivity. The shift of the Bragg wavelength in response to applied pressure is monitored with an optical spectrum analyser (OSA). The measured pressure sensitivity of FBG2 and FBG1 are found to be 5.85 x 10-2 MPa-1 and 2.07 x 10-2 MPa-1, which are approximately 18870 and 6677 times respectively higher than that can be sensed with a bare FBG. A very good linearity is observed between Bragg wavelength shift and pressure. This compact, low cost and robust design of the sensor can find applications in the areas of low and medium pressure measurement.

Vengal Rao, P.; Srimannarayana, K.; Kishore, P.; Sai Shankar, M.; Sengupta, D.; Saidi Reddy, P.

2012-05-01

229

Ultra-high sensitivity moment magnetometry of geological samples  

NASA Astrophysics Data System (ADS)

Scanning SQUID microscopy offers a unique combination of high spatial resolution and magnetic field sensitivity that allows for the detection of magnetic moments as weak as 10^-16 Am2. This opens the possibility of extending paleomagnetic analyses to samples that have not been accessible to standard moment magnetometry, for which the detection limit is 10^-12 Am2. Of particular interest are individual terrestrial and extraterrestrial particles of small size (< 500 ?m) that may preserve records of planetary dynamos and early nebular magnetic fields. Example targets include impact melt spherules, zircon and other silicate crystals, micrometeorites, cosmic dust, chondrules and refractory inclusions. These grains may be adequately modeled as small uniformly magnetized volumes, such that retrieving their magnetic moments from measured magnetic field maps does not require solving non-unique inverse problems. As a consequence, SQUID microscopes can be utilized as ultra-high sensitivity moment magnetometers. We show alternating field and thermal demagnetization data for several grains that demonstrate the performance of this technique. In addition, we compare scanning SQUID microscopy data with net moment measurements of the same samples performed by a commercial superconducting rock magnetometer. The results agree for stronger moments, as expected, but rapidly diverge as net moments fall below the lower 10^-10 Am2 range. These studies underscore the inability of conventional instruments not only to detect very weak moments but also to isolate contamination originating from background sources such as sample holders and mounts. We expect ultra-high sensitivity moment magnetometry using scanning SQUID microscopy will be a powerful tool in helping elucidate the formation of the solar system and planetary history.

Andrade Lima, E.; Weiss, B. P.

2012-12-01

230

A novel approach to high-sensitivity grating interferometry  

NASA Astrophysics Data System (ADS)

The authors propose a new approach for obtaining information about in-plane and out-of-plane displacements of an object tested using high-sensitivity grating interferometry. The interferences of each of the specimen grating diffraction orders with a reference beam are recorded separately. Computer addition and subtraction of the phase functions calculated from the interferograms give the in-plane and out-of-plane displacement values, respectively. The authors present their experimental work, and then compare their results with those obtained using a conventional grating interferometry approach.

Schmit, Joanna; Patorski, Krzysztof

1997-04-01

231

The Georgia Tech High Sensitivity Microwave Measurement System  

NASA Technical Reports Server (NTRS)

As observations and models of the planets become increasingly more accurate and sophisticated, the need for highly accurate laboratory measurements of the microwave properties of the component gases present in their atmospheres become ever more critical. This paper describes the system that has been developed at Georgia Tech to make these measurements at wavelengths ranging from 13.3 cm to 1.38 cm with a sensitivity of 0.05 dB/km at the longest wavelength and 0.6 db/km at the shortest wavelength.

Deboer, David R.; Steffes, Paul G.

1996-01-01

232

High sensitivity charge amplifier for ion beam uniformity monitor  

DOEpatents

An ion beam uniformity monitor for very low beam currents using a high-sensitivity charge amplifier with bias compensation. The ion beam monitor is used to assess the uniformity of a raster-scanned ion beam, such as used in an ion implanter, and utilizes four Faraday cups placed in the geometric corners of the target area. Current from each cup is integrated with respect to time, thus measuring accumulated dose, or charge, in Coulombs. By comparing the dose at each corner, a qualitative assessment of ion beam uniformity is made possible. With knowledge of the relative area of the Faraday cups, the ion flux and areal dose can also be obtained.

Johnson, Gary W. (Livermore, CA)

2001-01-01

233

High sensitive vectorial ?-probe for low frequency plasma waves  

NASA Astrophysics Data System (ADS)

A miniaturized multidimensional magnetic probe is developed for application in a low-temperature plasma environment. A very high sensitivity for low-frequency magnetic field fluctuations with constant phase run, a very good signal-to-noise ratio combined with an efficient electrostatic pickup rejection, renders the probe superior compared with any commercial solution. A two-step calibration allows for absolute measurement of amplitude and direction of magnetic field fluctuations. The excellent probe performance is demonstrated by measurements of the parallel current pattern of coherent electrostatic drift wave modes in the VINETA (versatile instrument for studies on nonlinearity, electromagnetism, turbulence, and applications) experiment.

Ullrich, Stefan; Grulke, Olaf; Klinger, Thomas; Rahbarnia, Kian

2013-11-01

234

High refractive index and temperature sensitivity LPGs for high temperature operation  

NASA Astrophysics Data System (ADS)

A fiber optic sensor for high sensitivity refractive index and temperature measurement able to withstand temperature up to 450 °C is reported. Two identical LPG gratings were fabricated, whereas one was coated with a high refractive index (~1.78) sol-gel thin film in order to increase its sensitivity to the external refractive index. The two sensors were characterized and compared in refractive index and temperature. Sensitivities of 1063 nm/RIU (1.338 - 1.348) and 260 pm/°C were achieved for refractive index and temperature, respectively.

Nascimento, I. M.; Gouveia, C.; Jana, Surnimal; Bera, Susanta; Baptista, J. M.; Moreira, Paulo; Biwas, Palas; Bandyopadhyay, Somnath; Jorge, Pedro A. S.

2013-11-01

235

Sturdy positioning with high sensitivity GPS sensors under adverse conditions.  

PubMed

High sensitivity GPS receivers have extended the use of GNSS navigation to environments which were previously deemed unsuitable for satellite signal reception. Under adverse conditions the signals become attenuated and reflected. High sensitivity receivers achieve signal reception by using a large number of correlators and an extended integration time. Processing the observation data in dynamic and rapidly changing conditions requires a careful and consistent treatment. Code-based autonomous solutions can cause major errors in the estimated position, due primarily to multipath effects. A custom procedure of autonomous GPS positioning has been developed, boosting the positioning performance through appropriate processing of code and Doppler observations. Besides the common positioning procedures, robust estimation methods have been used to minimise the effects of gross observation errors. In normal conditions, differential GNSS yields good results, however, under adverse conditions, it fails to improve significantly the receiver's position. Therefore, a so-called conditional DGPS has been developed which determines the position differentially by using data from the strong signals only. These custom-developed procedures have been tested in different conditions in static and kinematic cases and the results have been compared to those processed by the receiver. PMID:22163657

Trajkovski, Klemen Kozmus; Sterle, Oskar; Stopar, Bojan

2010-01-01

236

Flat Panel Detectors for High Sensitivity X-ray Imaging  

NASA Astrophysics Data System (ADS)

Flat panel, amorphous silicon transistor arrays are changing the technology for medical x-ray imaging. New materials, devices and structures can increase the performance of these radiation image sensors, extending the range of applications. We show that higher sensitivity is achieved with polycrystalline x-ray photoconductors based on the high atomic number materials, HgI2 and PbI_2. These detectors can operate near the theoretical sensitivity, and achieve single photon detection, although with low energy resolution. Including an amplifier in each pixel improves the signal-to-noise, and is accomplished using the higher device performance of laser recrystallized polysilicon. A pixel-level source follower amplifier is shown to add enough gain to overcome other noise sources. Another recent development is the use of a flat panel transistor array as the collection electrode for a gas electron multiplier (GEM) detector. The high gain of a GEM allows detection of the ionization track of a single x-ray photon, and forms the basis for x-ray polarization detection.

Street, Robert

2004-03-01

237

Sturdy Positioning with High Sensitivity GPS Sensors Under Adverse Conditions  

PubMed Central

High sensitivity GPS receivers have extended the use of GNSS navigation to environments which were previously deemed unsuitable for satellite signal reception. Under adverse conditions the signals become attenuated and reflected. High sensitivity receivers achieve signal reception by using a large number of correlators and an extended integration time. Processing the observation data in dynamic and rapidly changing conditions requires a careful and consistent treatment. Code-based autonomous solutions can cause major errors in the estimated position, due primarily to multipath effects. A custom procedure of autonomous GPS positioning has been developed, boosting the positioning performance through appropriate processing of code and Doppler observations. Besides the common positioning procedures, robust estimation methods have been used to minimise the effects of gross observation errors. In normal conditions, differential GNSS yields good results, however, under adverse conditions, it fails to improve significantly the receiver’s position. Therefore, a so-called conditional DGPS has been developed which determines the position differentially by using data from the strong signals only. These custom-developed procedures have been tested in different conditions in static and kinematic cases and the results have been compared to those processed by the receiver.

Trajkovski, Klemen Kozmus; Sterle, Oskar; Stopar, Bojan

2010-01-01

238

Design of a charge sensitive preamplifier on high resistivity silicon  

SciTech Connect

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the feedback loop. The output stage of the preamplifier can drive a load up to 20pF. The power dissipation of the preamplifier is 13mW. The amplifying elements are ''Single Sided Gate JFETs'' developed especially for this application. Preamplifiers connected to a low capacitance anode of a drift type detector should achieve a rise time of 20ns and have an equivalent noise charge (ENC), after a suitable shaping, of less than 50 electrons. This performance translates to a position resolution better than 3..mu..m for silicon drift detectors. 6 refs., 9 figs.

Radeka, V.; Rehak, P.; Rescia, S.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Strueder, L.; Kemmer, J.

1987-01-01

239

Design of a charge sensitive preamplifier on high resistivity silicon  

SciTech Connect

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the feedback loop. The output stage of the preamplifier can drive a load up to 20rhoF. The power dissipation of the preamplifier is 13mW. The amplifying elements are ''Single Sided Gate JFETs'' developed especially for this application. Preamplifiers connected to a low capacitance anode of a drift type detector should achieve a rise time of 20ns and have an equivalent noise charge (ENC), after a suitable shaping, of less than 50 electrons. This performance translates to a position resolution better than 3..mu..m for silicon drift detectors.

Radeka, V.; Rehak, P.; Rescia, S.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Struder, L.; Kemmer, J.

1988-02-01

240

Highly Sensitive Detection of Urinary Cadmium to Assess Personal Exposure  

PubMed Central

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 ?A/ppb/cm2) 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 National Institute of Standards and Technology (NIST) as well as in a human urine sample spiked with 0.25–1 ppb cadmium.

Argun, Avni A.; Banks, Ashley; Merlen, Gwendolynne; Tempelman, Linda A.; Becker, Michael F.; Schuelke, Thomas; Dweik, Badawi

2013-01-01

241

The Nikon C1si combines high spectral resolution, high sensitivity, and high acquisition speed.  

PubMed

Spectral imaging is a natural extension of the capabilities of confocal microscopes. The first confocal spectral imaging (CSI) instruments were able to acquire spectral data that allowed the emissions of overlapping fluorescent probes to be assigned to data channels representing a spectrum rather than a range of emission wavelengths. This marked a significant improvement over what could be done by channel series with standard confocal microscopes. However the performance of these earlier designs can fall short in one or more of the following areas; sensitivity, spectral resolution and reproducibility, acquisition speed, and unmixing accuracy. Nikon has recently introduced a new CSI instrument, C1si, that overcomes some of the more serious performance deficiencies of earlier designs through unique optical, electronic, and data handling advances. C1si uses a multianode photomultiplier tube (PMT) as the detector and typically acquires spectral data in a single scan. Sensitivity is enhanced over designs diffracting randomly polarized fluorescence by rotating the polarization of all emission photons to the S-plane, the plane for which the diffraction grating is most efficient. Three diffraction gratings are provided supporting wavelength sampling increments of 2.5, 5, and 10 nm. Improvements have been made in the digitization process to increase detection efficiency as well. C1si is calibrated to a high enough standard that it is possible to share and reproduce data between instruments. The algorithm implemented in the EZ-C1 software is able to accurately and repeatedly unmix fluorescent probes with emission peaks separated by as little as 5 nm. It is possible to unmix probes with emission peaks separated by 20 nm with a 10-1 brightness difference. Three probes can be unmixed with emission peaks contained within a 20 nm range. Acquisition is fast enough and the sensitivity is sufficient for C1si to acquire more than 100 frames of spectral time series data without serious photobleaching. PMID:16969806

Larson, Jeffrey M

2006-08-01

242

Multisite Comparison of High-Sensitivity Multiplex Cytokine Assays?†  

PubMed Central

The concentrations of cytokines in human serum and plasma can provide valuable information about in vivo immune status, but low concentrations often require high-sensitivity assays to permit detection. The recent development of multiplex assays, which can measure multiple cytokines in one small sample, holds great promise, especially for studies in which limited volumes of stored serum or plasma are available. Four high-sensitivity cytokine multiplex assays on a Luminex (Bio-Rad, BioSource, Linco) or electrochemiluminescence (Meso Scale Discovery) platform were evaluated for their ability to detect circulating concentrations of 13 cytokines, as well as for laboratory and lot variability. Assays were performed in six different laboratories utilizing archived serum from HIV-uninfected and -infected subjects from the Multicenter AIDS Cohort Study (MACS) and the Women's Interagency HIV Study (WIHS) and commercial plasma samples spanning initial HIV viremia. In a majority of serum samples, interleukin-6 (IL-6), IL-8, IL-10, and tumor necrosis factor alpha were detectable with at least three kits, while IL-1? was clearly detected with only one kit. No single multiplex panel detected all cytokines, and there were highly significant differences (P < 0.001) between laboratories and/or lots with all kits. Nevertheless, the kits generally detected similar patterns of cytokine perturbation during primary HIV viremia. This multisite comparison suggests that current multiplex assays vary in their ability to measure serum and/or plasma concentrations of cytokines and may not be sufficiently reproducible for repeated determinations over a long-term study or in multiple laboratories but may be useful for longitudinal studies in which relative, rather than absolute, changes in cytokines are important.

Breen, Elizabeth Crabb; Reynolds, Sandra M.; Cox, Christopher; Jacobson, Lisa P.; Magpantay, Larry; Mulder, Candice B.; Dibben, Oliver; Margolick, Joseph B.; Bream, Jay H.; Sambrano, Elise; Martinez-Maza, Otoniel; Sinclair, Elizabeth; Borrow, Persephone; Landay, Alan L.; Rinaldo, Charles R.; Norris, Philip J.

2011-01-01

243

Sensitivity of once-shocked, weathered high explosives  

SciTech Connect

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.

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

1998-07-01

244

High sensitivity, low profile neutron detector for safeguards measurements  

SciTech Connect

A neutron detector has been constructed and tested at Pacific Northwest Laboratory (PNL) for the purpose of making fast, high sensitivity measurements of neutron emitters in portal applications. The system is based upon glass fiber optic scintillators loaded with lithium-6 and operated to detect thermal neutrons. Due to their compact size. physical flexibility, freedom from microphonic pickup, and complete lack of environmental and safety concerns, these fibers are very suitable for some applications. The electronics needed for these fibers is somewhat more complex than for helium-3 proportional counters, but the entire electronics package (including the controlling computer) has been shrunk into a space of 20 {times} 25 {times} 2 cm. The prototype sensor is about 180 {times} 60 {times} 7 cm, but a final design now under construction measures 200 {times} 28 {times} 2.54 cm. The new, smaller detectors will be capable of ganging to achieve any needed sensitivity and will each weigh about 16 kg. The principles of operation of the fiber will be discussed as will the operational mode of the detector.

Miley, H.S.; Abraham, J.R.; Thompson, R.C.; Sunberg, D.S.

1993-12-01

245

Highly sensitive flow-injection chemiluminescence determination of pyrogallol compounds  

NASA Astrophysics Data System (ADS)

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.

Kanwal, Shamsa; Fu, Xiaohong; Su, Xingguang

2009-12-01

246

A wide bandwidth, high linearity hybrid charge-sensitive preamplifier for high-capacitance silicon detectors  

Microsoft Academic Search

A new hybrid charge-sensitive preamplifier with a sensitivity of 5 mV\\/MeV has been specifically designed to operate in conjunction with high-capacitance silicon detectors. The shape of the leading edge of its impulse response keeps fast (20 ns) and unchanged over the full output voltage swing (7 V), as is required in nuclear-physics experiments in which Pulse-Shape Analysis is used for

Roberto Bassini; Ciro Boiano; Angelo Pagano; Alberto Pullia

2003-01-01

247

Versatile, high-sensitivity faraday cup array for ion implanters  

DOEpatents

An improved Faraday cup array for determining the dose of ions delivered to a substrate during ion implantation and for monitoring the uniformity of the dose delivered to the substrate. The improved Faraday cup array incorporates a variable size ion beam aperture by changing only an insertable plate that defines the aperture without changing the position of the Faraday cups which are positioned for the operation of the largest ion beam aperture. The design enables the dose sensitivity range, typically 10.sup.11 -10.sup.18 ions/cm.sup.2 to be extended to below 10.sup.6 ions/cm.sup.2. The insertable plate/aperture arrangement is structurally simple and enables scaling to aperture areas between <1 cm.sup.2 and >750 cm.sup.2, and enables ultra-high vacuum (UHV) applications by incorporation of UHV-compatible materials.

Musket, Ronald G. (Danville, CA); Patterson, Robert G. (Dublin, CA)

2003-01-01

248

A wavelength modulation system for highly sensitive absorption spectroscopy  

NASA Astrophysics Data System (ADS)

We developed a newly designed wavelength modulation (WM) system for highly sensitive absorption spectroscopy. In our system, the WM is realized by yawing an output mirror in a monochromator. In order to control an amplitude ?? of the WM in a wide range, we employed a forced vibration of a permanent magnet driven by a magnetic field of a solenoid. Our system has an advantage of that the WM amplitude ?? can be adjusted in extensively wide range from 0.08 nm to 11 nm only by tuning a driving frequency of the applying current to the solenoid, because we utilize a resonance phenomenon of the forced vibration for adjustment of the WM amplitude. By using our system, we measured WM absorption spectra of a Cu2O thin film and found clearly spectral structures for weak 2-4P excitonic resonances in the WM absorption spectra.

Iwamitsu, K.; Aihara, S.; Shimamoto, T.; Fujii, A.; Akai, I.

2012-07-01

249

Highly sensitive hot electron bolometer based on disordered graphene  

PubMed Central

A bolometer is a device that makes an electrical resistive response to the electromagnetic radiation resulted from a raise of temperature due to heating. The combination of the extremely weak electron-phonon interactions along with its small electron heat capacity makes graphene an ideal material for applications in ultra-fast and sensitive hot electron bolometer. However, a major issue is that the resistance of pristine graphene weakly depends on the electronic temperature. We propose using disordered graphene to obtain a strongly temperature dependent resistance. The measured electrical responsivity of the disordered graphene bolometer reaches 6 × 106?V/W at 1.5?K, corresponding to an optical responsivity of 1.6 × 105?V/W. The deduced electrical noise equivalent power is 1.2 , corresponding to the optical noise equivalent power of 44?. The minimal device structure and no requirement for high mobility graphene make a step forward towards the applications of graphene hot electron bolometers.

Han, Qi; Gao, Teng; Zhang, Rui; Chen, Yi; Chen, Jianhui; Liu, Gerui; Zhang, Yanfeng; Liu, Zhongfan; Wu, Xiaosong; Yu, Dapeng

2013-01-01

250

Highly sensitive hot electron bolometer based on disordered graphene  

NASA Astrophysics Data System (ADS)

A bolometer is a device that makes an electrical resistive response to the electromagnetic radiation resulted from a raise of temperature due to heating. The combination of the extremely weak electron-phonon interactions along with its small electron heat capacity makes graphene an ideal material for applications in ultra-fast and sensitive hot electron bolometer. However, a major issue is that the resistance of pristine graphene weakly depends on the electronic temperature. We propose using disordered graphene to obtain a strongly temperature dependent resistance. The measured electrical responsivity of the disordered graphene bolometer reaches 6 × 106 V/W at 1.5 K, corresponding to an optical responsivity of 1.6 × 105 V/W. The deduced electrical noise equivalent power is 1.2 , corresponding to the optical noise equivalent power of 44 . The minimal device structure and no requirement for high mobility graphene make a step forward towards the applications of graphene hot electron bolometers.

Han, Qi; Gao, Teng; Zhang, Rui; Chen, Yi; Chen, Jianhui; Liu, Gerui; Zhang, Yanfeng; Liu, Zhongfan; Wu, Xiaosong; Yu, Dapeng

2013-12-01

251

Pajarito Monitor: A High-Sensitivity Monitoring System for Highly Enriched Uranium.  

National Technical Information Service (NTIS)

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-thro...

P. E. Fehlau K. Coop C. Garcia J. Martinez

1984-01-01

252

Instruments for highly sensitive investigations of volatiles and planetary solids  

NASA Astrophysics Data System (ADS)

Two miniature time-of-flight mass spectrometers, laser ablation/ionisation mass analyser (LMS) and a neutral gas mass spectrometer (NGMS), which were designed for chemical analysis of planetary solids and gaseous samples, respectively, will be introduced. LMS can perform full elemental and isotopic analysis of planetary materials (ablation mode) and can be used for detection of molecular compounds (desorption mode), which can be deposited on surfaces of planetary rocks. Current performance evaluations shows a high mass resolution m/?m~500 and the effective dynamic range of higher than 8 decades. The limits of the detection for both, metallic and nonmetallic (e.g., B, C, S, P, Si) elements are at some tens of ppb. The LMS instrument can also perform analysis of isotopic abundances at least at per mill 1. Introduction accuracy and precision. The second instrument, NGMS, is designed for the investigation of planetary gas samples (volatiles, atmospheric gases, composition of exosphere) and allows for measurements with a mass resolution m/?m ~ 1100 at an extended mass range, which is limited only by the available data acquisition memory. The repetition range of 10 kHz allows for highly sensitive studies with a high effective dynamic range of at least 7 decades.

Tulej, M.; Riedo, A.; Meyer, S.; Neuland, M.; Iakovleva, M.; Abplanalp, D.; Wurz, P.

2012-09-01

253

Sensitivity analysis for high quantiles of ochratoxin A exposure distribution.  

PubMed

Using available data from a consumption survey and contamination data on ochratoxin A (OA) in food, a sensitivity analysis (SA) for high quantiles (95th and 99th quantiles) of OA exposure distribution was carried out, obtained by a Monte Carlo simulation in French children. Exposure assessment for food contaminants is important to control the risk of foodborne diseases. Risk assessors are interested in high quantiles of contaminant exposure distributions. As these exposure distributions are generally very asymmetrical, it is difficult to obtain relevant and stable high quantiles in such a context. Determining OA exposure distribution is complex because it is based on the sum of elementary exposure distributions (eight foodstuffs are analysed here), and each one of these is the product of a consumption distribution and a contamination distribution. The SA enables us to quantify the influences of the parameter variability of the consumption and contamination probability density functions (pdf) which have been fitted to the data, our simulation model inputs, on the 95th and 99th quantiles of the output exposure distribution. After some preliminary trials, we have postulated a quadratic polynomial regression model for the quantiles of OA exposure distribution in view of undertaking this SA. This regression model comprises 32 main factors, their 496 two-factor interactions and their 32 quadratic terms. The 32 factors are the parameters of the fitted pdf: 16 parameters of Gamma distributions relative to the eight consumed foods and 16 parameters of Gamma distributions relative to the eight food OA contaminations. For an optimal parameter estimation of such a large model, we used an experimental design approach depending on a resolution-V fractional factorial design of 6561 experiments. The factor ranges are established by a preliminary study of bootstrap sampling. From the bootstrap samples, the factor ranges are obtained taking into account the correlation between the two parameters of the fitted Gamma pdf. A full exposure distribution is simulated for each of the 6561 experiments. The consumption dependencies are taken into account by the Iman and Conover method. On the basis of this analysis, validated and useful models for each desired quantile are obtained showing a major influence of the parameters of "Cereals" (consumption and contamination) and slightly less so for parameter of "Pork" consumption in the sensitivity of the quantiles. PMID:11999111

Albert, I; Gauchi, J P

2002-05-01

254

High-Speed Position-Sensitive Devices: Theory and Experiments  

NASA Astrophysics Data System (ADS)

Desirability for measurement of the correct high speed illuminated position becomes increasingly important in many applications. Using conventional position-sensitive devices (CPSDs), the illuminated-position can not be measured accurately. In search for measuring the fast illuminated -position, we are led to perform the study from two directions: (i) development of the new generalized model for one-dimensional (1-D) and two-dimensional (2-D) CPSDs to predict the performance characteristics in high-speed illuminated position measurement and (ii) proposing novel structures for the high-speed position-sensitive devices (HPSDs). The generalized models for 1-D and 2-D CPSD are derived based on the well known RC-transmission line approximation. The novelty of these generalized models lie in obtaining direct results for any kind of excitations, illuminated on CPSD. These model equations are used in analysis and prediction of dynamic performance of the very short-pulse (impulse-like) excitation of 0.2T_{rm c} for 1-D and 0.1T_{rm c} for 2-D CPSD, where T_{ rm c} represents the time-constant of PSD. Results show that 2-D CPSD is faster than 1-D CPSD having the same area, and for impulse-like excitation measurement using 2-D CPSD, the position resolution is more degraded in the near-electrode region than that of in the central region. The predicted results from models are consistent with the experimental results, performed using a-Si based CPSD. After this essential work on CPSD, study on HPSD is carried out proposing two novel structures. In the first, CPSD response-speed is improved using a mesh type resistive layer, a new structure for HPSD reducing junction capacitance. This concept making HPSD is verified, and compared with CPSD, fabricated using the same IC technology. Again, a theoretical based design strategy is proposed for investigating effects of the principle design parameters on device performances and to select the optimum design parameters for mesh-type PSD (MEPSD). Results indicate that MEPSD can be designed to operate one- to two-orders in magnitude faster than CPSD. In the second on study of HPSD, a novel structure consisting of matrix-structured photodetectors is proposed. This HPSD can detect illuminated position binarily. In the binary PSD (BPSD), each element is individually excited with illumination, and response-speed is dependent on speed of each element. For laboratory demonstration, an 8 x 8 matrix is chosen for the BPSD, fabricated using an a -Si technology and was verified the operation of newly proposed BPSD.

Dutta, Achyut Kumar

255

Graphene nanomesh as highly sensitive chemiresistor gas sensor.  

PubMed

Graphene is a one atom thick carbon allotrope with all surface atoms that has attracted significant attention as a promising material as the conduction channel of a field-effect transistor and chemical field-effect transistor sensors. However, the zero bandgap of semimetal graphene still limits its application for these devices. In this work, ethanol-chemical vapor deposition (CVD) of a grown p-type semiconducting large-area monolayer graphene film was patterned into a nanomesh by the combination of nanosphere lithography and reactive ion etching and evaluated as a field-effect transistor and chemiresistor gas sensors. The resulting neck-width of the synthesized nanomesh was about ?20 nm and was comprised of the gap between polystyrene (PS) spheres that was formed during the reactive ion etching (RIE) process. The neck-width and the periodicities of the graphene nanomesh (GNM) could be easily controlled depending on the duration/power of the RIE and the size of the PS nanospheres. The fabricated GNM transistor device exhibited promising electronic properties featuring a high drive current and an I(ON)/I(OFF) ratio of about 6, significantly higher than its film counterpart. Similarly, when applied as a chemiresistor gas sensor at room temperature, the graphene nanomesh sensor showed excellent sensitivity toward NO(2) and NH(3), significantly higher than their film counterparts. The ethanol-based graphene nanomesh sensors exhibited sensitivities of about 4.32%/ppm in NO(2) and 0.71%/ppm in NH(3) with limits of detection of 15 and 160 ppb, respectively. Our demonstrated studies on controlling the neck width of the nanomesh would lead to further improvement of graphene-based transistors and sensors. PMID:22931286

Paul, Rajat Kanti; Badhulika, Sushmee; Saucedo, Nuvia M; Mulchandani, Ashok

2012-10-01

256

Highly sensitive plasma absorption probe for measuring low-density high-pressure plasmas  

NASA Astrophysics Data System (ADS)

This article reports a new type of sensitive plasma absorption probe (PAP), which is characterized with a thin wire antenna directly exposed to plasma. In the sensitive PAP, the power reflection coefficient resonantly decreases at a certain frequency due to absorption of a surface wave, which is excited along a sheath formed around the antenna. The electron density is derived from the measured absorption frequency in comparison to a wave dispersion relation: the dispersion is calculated under assumptions that the sheath width is twice the Debye length and that wavelength is twice the antenna length. This sensitive PAP also enables measurements of very low electron densities (~108 cm-3) and very high pressures (~10 Torr), in comparison to a conventional standard PAP. In addition, both electron temperature and electron density can be measured using a pair of sensitive PAPs of different antenna radii.

Nakamura, K.; Ohata, M.; Sugai, H.

2003-01-01

257

Background-free Piezoresponse Force Microscopy with high sensitivity  

NASA Astrophysics Data System (ADS)

Piezoresponse Force Microscopy (PFM) detects small mechanical deformation of a specimen by applying an AC voltage between a conductive AFM tip (as a top electrode) and the bottom electrode. It is widely used for visualizing ferroelectric domain patterns with high lateral resolution. In nominal or commercial setups, the PFM signal is contaminated by the so-called ``system-inherent background'' with a complex frequency spectrum which consists of many cross-talk resonances with peak amplitude over 10 pm/V [1]. The presence of the system-inherent background will severely distort the PFM contrast (especially the phase signal) and the domain pattern in PFM images of ferroelectrics with weak piezoelectric response (<1 pm/V). Although the system-inherent background can be subtracted out by proper calibration using a non-piezoelectric material (e.g. glass slides), it is highly desirable to eliminate it directly from PFM setup for background-free measurements. Here we demonstrate that the system-inherent background can be eliminated using carefully designed electric wiring of PFM setup. Results of background-free PFM detection with excellent sensitivity(<=0.1 pm/V) will be presented. [4pt] [1] Jungk et al, Appl. Phys. Lett. 89 163507 (2006).

Wang, Wenbo; Geng, Yanan; Wu, Weida

2013-03-01

258

High sensitivity technetium analysis using negative thermal ionization mass spectrometry  

SciTech Connect

Determination of the reaction products of solar neutrinos with /sup 98/Mo and /sup 97/Mo to produce /approximately/10/sup 8/ atoms of /sup 98/Tc and /sup 97/Tc in 10/sup 4/ tons of ore for the last several million years have prompted the development of highly sensitive isotopic analytical technique for technetium. Secular equilibrium /sup 99/Tc, present in the ore at 10/sup 8/ to 10/sup 9/ atom levels will be used for an internal tracer to fix absolute atom amounts. Previous work has suggested that negative thermal ionization can produce high ionization efficiency for certain selected elements, including technetium. Negative thermal ionization has several advantages over the positive ion approach. Technetium forms the pertechnetate ion while the most common and abundant isobaric impurity, molybdenum, forms MoO/sub 3//sup /minus//. In addition, technetium forms negative ions very efficiently; efficiencies of >2% have been measured. Positive ion techniques are much less efficient. Organic impurities also are much less troublesome in the negative ionization mode. 6 refs.

Rokop, D.J.; Schroeder, N.C.; Wolfsberg, K.

1988-01-01

259

High-sensitivity thermoluminescence applied to environmental monitoring  

NASA Astrophysics Data System (ADS)

We describe the development of a new environmental TLD Dosemeter Badge and dose computation algorithm based on the new LiF:Mg,Cu,P material. LiF:Mg,Cu,P, with its high sensitivity, tissue equivalence, energy independence, and low fading characteristics, is a natural choice for environmental dosimetry. The badge consists of a card and a plastic holder. The card contains four LiF:Mg,Cu,P elements, each 3.2 mm square and 0.4 mm thick, encapsulated in TeflonR. The badge is symmetrical and uses four filters to discriminate low and high energy photons and to determine Directional Dose Equivalent, H'(0.07,(alpha) ), and Ambient Dose Equivalent, H*(10). Extensive data was taken based on irradiations of 920 dosemeters to both single and mixed fields of photons and betas. In addition, angular incidence data of various fields was taken. The approach to the algorithm is empirical and is based on this data. While most algorithms are based solely on perpendicular incidence exposure, this algorithm is being developed to account for the angular response of the dosemeter. This paper will present the algorithm for perpendicular irradiation; the angular response portion is in development. The dosemeter is designed to meet the criteria of the new draft standard ANSI N13.29, 'Environmental Dosimetry Performance -- Criteria for Testing.'

Velbeck, K. J.; Zhang, L.; Rotunda, Joe E.; Moscovitch, Marko

1999-02-01

260

Highly sensitive and multiplexed platforms for allergy diagnostics  

NASA Astrophysics Data System (ADS)

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 offers four significant advantages compared to existing sensing technologies: IRIS i) corrects for any variation in probe immobilization, ii) detects proteins from attomolar to nanomolar concentrations in unprocessed biological samples, iii) unambiguously discriminates nanoparticles tags on a robust and physically large sensor area, iv) detects protein targets with conjugated nanoparticle tags (~40nm diameter), which minimally affect assay kinetics compared to conventional microparticle tagging methods, and v) utilizes components that make the instrument inexpensive, robust, and portable. This platform was successfully validated on patient serum and whole blood samples with documented allergy profiles (ImmunoCAPRTM, ThermoFisher Scientific).

Monroe, Margo R.

261

High-expression ?(1) adrenergic receptor/cell membrane chromatography method based on a target receptor to screen active ingredients from traditional Chinese medicines.  

PubMed

?-Adrenergic receptors are important targets for drug discovery. We have developed a new ?1 -adrenergic receptor cell membrane chromatography (?1 AR-CMC) with offline ultra-performance LC (UPLC) and MS method for screening active ingredients from traditional Chinese medicines. In this study, Chinese hamster ovary-S cells with high ?1 AR expression levels were established and used to prepare a cell membrane stationary phase in a ?1 AR-CMC model. The retention fractions were separated and identified by the UPLC-MS system. The screening results found that isoimperatorin from Rhizoma et Radix Notopterygii was the targeted component that could act on ?1 AR in similar manner of metoprolol as a control drug. In addition, the biological effects of active component were also investigated in order to search for a new type of ?1 AR antagonist. It will be a useful method for drug discovery as a leading compound resource. PMID:24272943

Yue, Yuan; Xue, Hui; Wang, Xin; Yang, Qian; Song, Yanhong; Li, Xiaoni

2014-02-01

262

Multi-residue and multi-class determination of antibiotics in gilthead sea bream (Sparus aurata) by ultra high-performance liquid chromatography-tandem mass spectrometry.  

PubMed

This paper describes a method for the determination of 41 antibiotics from seven different classes in gilthead sea bream (Sparus aurata) by ultra-high-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS). Sulfonamides, trimethoprim, tetracyclines, macrolides, quinolones, penicillins and chloramphenicol were simultaneously determined. Fourteen procedures for sample treatment were tested and an extraction with acetonitrile and ethylenediaminetetra acetic acid was found to be the best option. The methodology was validated in accordance with Decision 2002/657/EC. Precision in terms of relative standard deviation (RSD) was under 17% for all compounds, and the recoveries ranged from 92% to 111%. CC? and CC? were determined according to the maximum residue limit or the minimum required performance limit, when necessary. The validation provided evidence that the method was suitable for application in routine analysis for the detection and confirmation of antibiotics in muscle of gilthead sea bream, an important and intensively produced fish in aquaculture. PMID:24512256

Freitas, Andreia; Leston, Sara; Rosa, João; Castilho, Maria da Conceição; Barbosa, Jorge; Rema, Paulo; Pardal, Miguel Ângelo; Ramos, Fernando

2014-05-01

263

Highly birefringent microstructured fibers with enhanced sensitivity to hydrostatic pressure.  

PubMed

We designed, manufactured and characterized two birefringent microstructured fibers that feature a 5-fold increase in polarimetric sensitivity to hydrostatic pressure compared to the earlier reported values for microstructured fibers. We demonstrate a good agreement between the finite element simulations and the experimental values for the polarimetric sensitivity to pressure and to temperature. The sensitivity to hydrostatic pressure has a negative sign and exceeds -43 rad/MPa x m at 1.55 microm for both fibers. In combination with the very low sensitivity to temperature, this makes our fibers the candidates of choice for the development of microstructured fiber based hydrostatic pressure measurement systems. PMID:20639996

Martynkien, Tadeusz; Statkiewicz-Barabach, Gabriela; Olszewski, Jacek; Wojcik, Jan; Mergo, Pawe?; Geernaert, Thomas; Sonnenfeld, Camille; Anuszkiewicz, Alicja; Szczurowski, Marcin K; Tarnowski, Karol; Makara, Mariusz; Skorupski, Krzysztof; Klimek, Jacek; Poturaj, Krzysztof; Urbanczyk, Waclaw; Nasilowski, Tomasz; Berghmans, Francis; Thienpont, Hugo

2010-07-01

264

Comparisons of high, medium, and low feedback sensitivity for the control of heart-rate acceleration  

Microsoft Academic Search

Thirty-four student volunteers were randomly assigned to one of three feedback sensitivity conditions: high sensitivity, medium sensitivity, or low sensitivity. Each subject received four sessions of biofeedback training with instructions to accelerate heart rate. In each condition, analogue feedback was provided during heart-rate acceleration trials. In addition to heart rate, frontal EMG and digital skin temperature were also recorded. Results

Donald A. Williamson; Mark P. Jarrell; John E. Monguillot; Peter Hutchinson

1983-01-01

265

Sensitivity Analysis of Cell Neutronic Parameters in High-Conversion Light-Water Reactors  

Microsoft Academic Search

The sensitivity coefficients of neutronic performance parameters in high-conversion LWR cells have been calculated by means of the SAINT code. In order to show the specific features of the sensitivity coefficients in the HCLWR cells, the differences between sensitivities were investigated for cells with different moderator to fuel volume ratios and different Pu enrichments. The burnup dependence of the sensitivities

Makoto NAKANO; Toshikazu TAKEDA; Hideki TAKANO

1987-01-01

266

Highly sensitive hot electron bolometer based on disordered graphene.  

PubMed

A bolometer is a device that makes an electrical resistive response to the electromagnetic radiation resulted from a raise of temperature due to heating. The combination of the extremely weak electron-phonon interactions along with its small electron heat capacity makes graphene an ideal material for applications in ultra-fast and sensitive hot electron bolometer. However, a major issue is that the resistance of pristine graphene weakly depends on the electronic temperature. We propose using disordered graphene to obtain a strongly temperature dependent resistance. The measured electrical responsivity of the disordered graphene bolometer reaches 6 × 10(6) V/W at 1.5 K, corresponding to an optical responsivity of 1.6 × 10(5) V/W. The deduced electrical noise equivalent power is 1.2 fW/?Hz, corresponding to the optical noise equivalent power of 44 fW/?Hz. The minimal device structure and no requirement for high mobility graphene make a step forward towards the applications of graphene hot electron bolometers. PMID:24346418

Han, Qi; Gao, Teng; Zhang, Rui; Chen, Yi; Chen, Jianhui; Liu, Gerui; Zhang, Yanfeng; Liu, Zhongfan; Wu, Xiaosong; Yu, Dapeng

2013-01-01

267

ASIC for High Rate 3D Position Sensitive Detectors  

SciTech Connect

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.

Vernon, E.; De Geronimo, G.; Ackley, K.; Fried, J.; He, Z.; Herman, C.; Zhang, F.

2010-06-16

268

Highly sensitive tube-topology magnetoelectric magnetic sensors  

NASA Astrophysics Data System (ADS)

Magnetoelectric (ME) composites have drawn increasing interest in recent years due to advancements in the technology resulting in enhanced ME coupling coefficients, stable room-temperature operation, sub-nanoTesla noise floor, low- and zero-biased operation, and fabrication of compact, miniaturized devices. Now, more than ever, practical use of ME devices in commercial magnetometry applications is feasible, while continued development of numerous other applications, such as voltage-tunable magnetic field generators, voltage-tunable inductors, and magnetically-tunable capacitors, bolster the overall usefulness of ME composites as a valuable technology. This dissertation focuses on development and characterization of tube-topology ME composites as magnetic field sensors. The novel topology is most notable for demonstrating high zero-external-bias sensitivity, low noise floor, low-frequency bandwidth, and self-powered, stable room temperature operation. Numerous characterization studies are included in this work where several devices are analyzed as a function of test-field, DC-bias field, geometry, material choice, and more. The overall conclusions drawn upon these results indicate strongly that the tube-topology ME magnetic field sensor holds promise to compete with existing hall-effect and flux-gate magnetometers. ME composites are at the tipping point of commercialization for use in magnetometry applications and are emerging as a valuable technology for use in numerous creative ways.

Gillette, Scott Matthew

269

High sensitivity DNA detection using gold nanoparticle functionalised polyaniline nanofibres.  

PubMed

Polyaniline (PANI) nanofibres (PANI-NF) have been modified with chemically grown gold nanoparticles to give a nanocomposite material (PANI-NF-AuNP) and deposited on gold electrodes. Single stranded capture DNA was then bound to the gold nanoparticles and the underlying gold electrode and allowed to hybridise with a complementary target strand that is uniquely associated with the pathogen, Staphylococcus aureus (S. aureus), that causes mastitis. Significantly, cyclic voltammetry demonstrates that deposition of the gold nanoparticles increases the area available for DNA immobilisation by a factor of approximately 4. EPR reveals that the addition of the Au nanoparticles efficiently decreases the interactions between adjacent PANI chains and/or motional broadening. Finally, a second horseradish peroxidase (HRP) labelled DNA strand hybridises with the target allowing the concentration of the target DNA to be detected by monitoring the reduction of a hydroquinone mediator in solution. The sensors have a wide dynamic range, excellent ability to discriminate DNA mismatches and a high sensitivity. Semi-log plots of the pathogen DNA concentration vs. faradaic current were linear from 150×10(-12) to 1×10(-6) mol L(-1) and pM concentrations could be detected without the need for molecular, e.g., PCR or NASBA, amplification. PMID:21159503

Spain, Elaine; Kojima, Robert; Kaner, Richard B; Wallace, Gordan G; O'Grady, Justin; Lacey, Katrina; Barry, Thomas; Keyes, Tia E; Forster, Robert J

2011-01-15

270

Highly sensitive strain detection in silicon by reflectance anisotropy spectroscopy  

NASA Astrophysics Data System (ADS)

Reflectance anisotropy spectroscopy (RAS) measurements were performed on strained silicon (Si) stripes cut from crystalline silicon wafers. Strains were externally applied using a device developed especially for the study of layers and layered structures. The dependence of the RAS signal intensity on strain was measured for (100), (110), and (111) silicon wafers strained along [001] and [011]. In these configurations, the RAS spectra show a derivativelike structure at 3.4 eV, which increases in amplitude linearly with strain. While RAS line shapes depend on the orientation of the Si wafer and the crystallographic directions along which strains are applied, RAS intensities depend on strain magnitude. Strains as low as 10-5 can be measured, which is two orders of magnitude smaller than those detected with standard techniques such as Raman, piezoelectroreflectance spectroscopy (PERS), or x-ray diffraction (XRD). The experimental RAS spectra are found to be in good agreement with spectra calculated on the basis of the spectral response of the published piezo-optical tensor components. It is concluded that RAS provides a highly sensitive tool for the detection of strain induced bulk anisotropies. Strain calibrated RAS spectra can be used for strain-stress characterization of semiconductor layers and microstructures with a higher efficiency than that achieved by Raman, PERS, and XRD. Combined with growth techniques, RAS spectroscopy can be also used for in situ control of strain during semiconductor growth.

Papadimitriou, D.; Richter, W.

2005-08-01

271

Highly sensitive nanomechanical immunosensor using half antibody fragments.  

PubMed

The improvement of sensitivity is of great significance to the application of biochemical sensor. In this study, we propose a micocantilever-based immunosensor in surface stress mode using half antibody fragments as receptor molecules. The thiol-containing half antibody fragment was obtained with a low loss of antibody biological activity and then was covalently and orientedly immobilized on the gold surface of microcantilevers via two native thiol groups. Such a one-step reaction and immobilization of receptor molecule simplify the preparation process of micocantilever immunosensor. Using shortened and highly oriented half antibody fragments as receptor molecules, the generation of surface stress and the transmission of stress from the interaction region of molecules to the surface of the microcantilever have been elevated significantly. The limit of detection (LOD) of the presented sensor has been significantly lowered to 1 pg/mL, or 1.1 pM in equivalence, which is a 500-fold improvement when compared with intact full antibody coated conventional micocantilever sensors. The results indicate that the half antibody fragment is well suited for the functionalization of the microcantilever surface and is generally applicable to all microcantilever immunosensor development, and this principle will help to design a functional film of devices with significantly lower LOD. PMID:24707987

Wu, Shangquan; Liu, Hong; Liang, Xin M; Wu, Xiaoping; Wang, Baomin; Zhang, Qingchuan

2014-05-01

272

Design of high sensitivity detector for underwater communication system  

NASA Astrophysics Data System (ADS)

Al0.52In0.48P is the largest bandgap material in III-V non-nitride semiconductors that is lattice matched to a readily available substrate (GaAs). Having a bandgap narrower than that of GaN enables it to detect wavelengths around 480 nm. Such wavelengths have the best transmittance underwater and may be used as a carrier in underwater communication systems. We present an Al0.52In0.48P homo-junction Separate-Absorption-Multiplication-Avalanche-Photodiode (SAMAPD) as a high sensitivity detector for such an application. By increasing the neutral and space-charge region thicknesses, the peak response wavelength can be tuned to longer wavelengths with a narrower full-width-half-maximum (FWHM). The quantum efficiency of the detector reduces with FWHM and this is compensated by having an avalanche gain. At room temperature, the SAM-APD has a dark current of <20 pA for a 210 ?m radius device up to 99.9% of breakdown voltage. The structure gives a narrow spectral FWHM of 22 nm with centre wavelength of 482 nm. An external quantum efficiency of 33% and 6410% at 482 nm is obtained at bias voltage of -19 V and -92.6 V respectively.

Cheong, J. S.; Ong, J. S. L.; Ng, J. S.; Krysa, A. B.; Bastiman, F.; David, J. P. R.

2013-11-01

273

High sensitivity imaging Thomson scattering for low temperature plasma.  

PubMed

A highly sensitive imaging Thomson scattering system was developed for low temperature (0.1-10 eV) plasma applications at the Pilot-PSI linear plasma generator. The essential parts of the diagnostic are a neodymium doped yttrium aluminum garnet laser operating at the second harmonic (532 nm), a laser beam line with a unique stray light suppression system and a detection branch consisting of a Littrow spectrometer equipped with an efficient detector based on a "Generation III" image intensifier combined with an intensified charged coupled device camera. The system is capable of measuring electron density and temperature profiles of a plasma column of 30 mm in diameter with a spatial resolution of 0.6 mm and an observational error of 3% in the electron density (n(e)) and 6% in the electron temperature (T(e)) at n(e) = 4 x 10(19) m(-3). This is achievable at an accumulated laser input energy of 11 J (from 30 laser pulses at 10 Hz repetition frequency). The stray light contribution is below 9 x 10(17) m(-3) in electron density equivalents by the application of a unique stray light suppression system. The amount of laser energy that is required for a n(e) and T(e) measurement is 7 x 10(20)n(e) J, which means that single shot measurements are possible for n(e)>2 x 10(21) m(-3). PMID:18248032

van der Meiden, H J; Al, R S; Barth, C J; Donné, A J H; Engeln, R; Goedheer, W J; de Groot, B; Kleyn, A W; Koppers, W R; Lopes Cardozo, N J; van de Pol, M J; Prins, P R; Schram, D C; Shumack, A E; Smeets, P H M; Vijvers, W A J; Westerhout, J; Wright, G M; van Rooij, G J

2008-01-01

274

High-sensitivity photoacoustic detection of chemical warfare agents  

Microsoft Academic Search

We report sensitive and selective detection of Diisopropyl methylphosphonate (DIMP) - a decomposition product of Sarin and a common surrogate for the nerve gases - in presence of several gases expected to be interferences in an urban setting. By employing photoacosutic spectroscopy with broadly tunable CO2 laser as a radiation source we demonstrate detection sensitivity for DIMP in the presence

Michael B. Pushkarsky; Michael E. Webber; Tyson MacDonald; C. Kumar N. Patel

2004-01-01

275

High sensitivity metamaterial based bi-material terahertz sensor  

NASA Astrophysics Data System (ADS)

We report on the fabrication of a microelectromechanical systems (MEMS) based bi-material terahertz (THz) detector integrated with a metamaterial structure to provide high absorption at 3.8 THz. The absorbing element of the sensor was designed with a resonant frequency that matches the quantum cascade laser illumination source, while simultaneously providing structural support, desired thermomechanical properties and optical read-out access. It consists of a periodic array of aluminum squares separated from a homogeneous aluminum (Al) ground plane by a silicon-rich silicon oxide (SiOx) layer. The absorbing element is connected to two Al/SiOx microcantilevers (legs), anchored to a silicon substrate, which acts as a heat sink, allowing the sensor to return to its unperturbed position when excitation is terminated. The metamaterial structure absorbs the incident THz radiation and transfers the heat to the legs where the significant difference between thermal expansion coefficients of Al and SiOx causes the structure to deform proportionally to the absorbed power. The amount of deformation is probed optically by measuring the displacement of a laser beam reflected on the Al ground plane of the metamaterial absorber. Measurement showed that the fabricated absorber has nearly 95% absorption at 3.8 THz. The responsivity and time constant were found to be 1.2 deg/?W and 0.65 s, respectively. The minimum detectable incident power including the readout noise is around 9 nW. The obtained high sensitivity and design flexibility indicate that sensor can be further tuned to achieve the required parameters for real time THz imaging applications.

Alves, Fabio; Grbovic, Dragoslav; Kearney, Brian; Karunasiri, Gamani

2013-03-01

276

Introducing wet aerosols into the static high sensitivity ICP (SHIP).  

PubMed

A demountable design of the static high sensitivity ICP (SHIP) for optical emission spectrometry is presented, and its use as an excitation source with the introduction of wet aerosols was investigated. Aerosols were produced by standard pneumatic sample introduction systems, namely a cross flow nebulizer, Meinhard nebulizer and PFA low flow nebulizer, which have been applied in conjunction with a double pass and a cyclonic spray chamber. The analytical capabilities of these sample introduction systems in combination with the SHIP system were evaluated with respect to the achieved sensitivity. It was found that a nebulizer tailored for low argon flow rates (0.3-0.5 L min(-1)) is best suited for the low flow plasma (SHIP). An optimization of all gas flow rates of the SHIP system with the PFA low flow nebulizer was carried out in a two-dimensional way with the signal to background ratio (SBR) and the robustness as optimization target parameters. Optimum conditions for a torch model with 1-mm injector tube were 0.25 and 0.36 L min(-1) for the plasma gas and the nebulizer gas, respectively. A torch model with a 2-mm injector tube was optimized to 0.4 L min(-1) for the plasma gas and 0.44 L min(-1) for the nebulizer gas. In both cases the SHIP system saves approximately 95% of the argon consumed by conventional inductively coupled plasma systems. The limits of detection were found to be in the low microgram per litre range and below for many elements, which was quite comparable to those of the conventional setup. Furthermore, the short-term stability and the wash out behaviour of the SHIP were investigated. Direct comparison with the conventional setup indicated that no remarkable memory effects were caused by the closed design of the torch. The analysis of a NIST SRM 1643e (Trace Elements in Water) with the SHIP yielded recoveries of 97-103% for 13 elements, measured simultaneously. PMID:17593358

Scheffer, Andy; Engelhard, Carsten; Sperling, Michael; Buscher, Wolfgang

2007-08-01

277

Pajarito Monitor: a high-sensitivity monitoring system for highly enriched uranium  

Microsoft Academic Search

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

P. E. Fehlau; K. Coop; C. Jr. Garcia; J. Martinez

1984-01-01

278

Dye sensitization in a highly sensitive photopolymerizable system for real-time holography  

NASA Astrophysics Data System (ADS)

The spectral sensitivity and the enhancement of the energetic sensitivity are important points to the optimization of photopolymerizable materials. We have studied a polymeric system based on polyvinylalcohol as binder, monomers as acrylamide and dihydroxyethylenbisacrylamide and a photoinitiator system composed by triethanolamine and methylene blue. This system was irradiated with an Ar+ laser tuned at 514 nm, where this material do not absorb. Obtaining diffraction efficiencies of 55% with an energetic expositions of 500 mJcm-2. A possible mechanism of initiation of the photopolymerization process has been proposed by the presence of semireduced methylene blue that has an absorption band at 520 nm.

Blaya-Escarre, Salvador; Carretero-Lopez, Luis; Madrigal, Roque F.; Mallavia, Ricardo M.; Fimia, Antonio

1999-03-01

279

Ultra-High Sensitive Magnetoelectric Nanocomposite Current Sensors.  

National Technical Information Service (NTIS)

Sintered magnetoelectric composites generally exhibit reduced sensitivity due to: 1) breakage and aggregation of ferrite coating during compaction forming path of reduced resistivity, 2) coarsening of piezoelectric particle leading to interfacial porosity...

C. Kim J. P. Liu S. Priya

2009-01-01

280

High-intensity xenon plasma discharge lamp for bulk-sensitive high-resolution photoemission spectroscopy  

SciTech Connect

We have developed a highly brilliant xenon (Xe) discharge lamp operated by microwave-induced electron cyclotron resonance (ECR) for ultrahigh-resolution bulk-sensitive photoemission spectroscopy (PES). We observed at least eight strong radiation lines from neutral or singly ionized Xe atoms in the energy region of 8.4-10.7 eV. The photon flux of the strongest Xe I resonance line at 8.437 eV is comparable to that of the He I{alpha} line (21.218 eV) from the He-ECR discharge lamp. Stable operation for more than 300 h is achieved by efficient air-cooling of a ceramic tube in the resonance cavity. The high bulk sensitivity and high-energy resolution of PES using the Xe lines are demonstrated for some typical materials.

Souma, S.; Sato, T.; Takahashi, T.; Baltzer, P. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); MB Scientific AB, Seminariegatan 29B, Uppsala 752 28 (Sweden)

2007-12-15

281

Highly sensitive and selective colorimetric sensing of antibiotics in milk.  

PubMed

Antibiotics residues in foods are very harmful to human beings. Determination of antibiotics residues relies largely on the availability of adequate analytical techniques. Currently, there is an urgent need for on site and real time detection of antibiotics in food. In this work, a novel one step synthesis of gold nanoparticles (AuNPs) was proposed using pyrocatechol violet (PCV) as a reducer agent. Highly sensitive and selective colorimetric detection of four antibiotics kanamycin mono sulfate (KA), neomycin sulfate (NE), streptomycin sulfate (ST) and bleomycin sulfate (BL) was realized during the formation of AuNPs. PCV has -OH groups and these antibiotics have -OH, -NH2, -NH- groups, so there may be some special hydrogen-bonding interactions between PCV and these antibiotics. Therefore, the presence of KA, NE, ST and BL would influence the synthesis of AuNPs, then the color and state of AuNPs would change, which could be observed with the naked eye or a UV-vis spectrophotometer. Results showed that A670 was linear with the logarithm of KA concentration in the range from 1.0×10(-8) to 5.0×10(-7)M and 5.0×10(-7) to 5.5×10(-5)M. The detection limit of KA was 1.0×10(-9)M (S/N=3). The coexisting substances including 1.0×10(-5)M phenylalanine, alanine, glycerol, glucose, Mg(2+), Ca(2+), Na(+), K(+), CO3(2-), SO4(2-), NO3(-), Cl(-) and Br(-) did not affect the determination of 1.0×10(-7)M antibiotics. In particular, the proposed method could be applied successfully to the detection of antibiotics in the pretreated liquid milk products. PMID:23639400

Zhang, Xiaofang; Zhang, Yang; Zhao, Hong; He, Yujian; Li, Xiangjun; Yuan, Zhuobin

2013-05-17

282

High sensitivity evanescent field fiber Bragg grating sensor  

Microsoft Academic Search

Increased sensitivity to change in surrounding index is shown by etching the core of a fiber Bragg grating. A maximum sensitivity of 1394 nm\\/riu is achieved as the surrounding index approaches the core index. Assuming a detectable spectral resolution of 0.01 nm realized in the experiment, the sensor achieves a minimum detectable index resolution of 7.2×10-6 when the index of

Athanasios N. Chryssis; Sang M. Lee; Sang B. Lee; Simarjeet S. Saini; Mario Dagenais

2005-01-01

283

Sensitivity study on high pressurizer pressure trip margin of UCN 3 and 4.  

National Technical Information Service (NTIS)

Sensitivity studies for variables which affect high pressurizer pressure trip margin are performed using LTCUCN computer code which is performance analysis code of UCN 3 and 4. As the results of sensitivity study, initial pressurizer pressure, SBCS quick ...

S. H. Sohn W. S. Jeong H. T. Seo J. T. Seo

1996-01-01

284

Development of a high-speed and a high-sensitive laser scanning magneto-optical imaging system  

Microsoft Academic Search

A high-speed and a high-sensitive laser scanning magneto-optical (MO) imaging system have been developed. In the high-speed imaging mode, we have succeeded in almost the real time observation of MO images with the sensitivity better than 100 muT. On the other hand, in the high-sensitive mode using an acoustic-optic modulator and a RF lock-in amplifier, it was found that the

H. Murakami; R. Kitamura; I. Kawayama; M. Tonouchi

2009-01-01

285

Model dependence of isospin sensitive observables at high densities  

NASA Astrophysics Data System (ADS)

Within two different frameworks of isospin-dependent transport model, i.e., Boltzmann-Uehling-Uhlenbeck (IBUU04) and Ultrarelativistic Quantum Molecular Dynamics (UrQMD) transport models, sensitive probes of nuclear symmetry energy are simulated and compared. It is shown that neutron to proton ratio of free nucleons, ?-/?+ ratio as well as isospin-sensitive transverse and elliptic flows given by the two transport models with their “best settings”, all have obvious differences. Discrepancy of numerical value of isospin-sensitive n/p ratio of free nucleon from the two models mainly originates from different symmetry potentials used and discrepancies of numerical value of charged ?-/?+ ratio and isospin-sensitive flows mainly originate from different isospin-dependent nucleon-nucleon cross sections. These demonstrations call for more detailed studies on the model inputs (i.e., the density- and momentum-dependent symmetry potential and the isospin-dependent nucleon-nucleon cross section in medium) of isospin-dependent transport model used. The studies of model dependence of isospin sensitive observables can help nuclear physicists to pin down the density dependence of nuclear symmetry energy through comparison between experiments and theoretical simulations scientifically.

Guo, Wen-Mei; Yong, Gao-Chan; Wang, Yongjia; Li, Qingfeng; Zhang, Hongfei; Zuo, Wei

2013-10-01

286

Development of High Temperature/High Sensitivity Novel Chemical Resistive Sensor  

SciTech Connect

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 LnBaCo2O5+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.

Chen, Chonglin; Nash, Patrick; Ma, Chunrui; Enriquez, Erik; Wang, Haibing; Xu, Xing; Bao, Shangyong; Collins, Gregory

2013-08-13

287

Design and performance of a high-sensitivity high-resolution thermal video system  

NASA Astrophysics Data System (ADS)

A high sensitivity thermal video system has been jointly developed by Cincinnati Electronics Corporation and Nippon Avionics Company, Ltd. (Avio) of Japan, the TVS-8000. The system utilizes an Indium Antimonide staring focal plane array sensor, cooled by a Stirling cryocooler. The sensor/cooler assembly is connected to a separate video processor, display, and electronics assembly. The TVS-8000 product series offers the performance advantages of combining a high sensitivity focal plane array sensor with all of the advanced features and quality of an Avio Thermal Video System (TVS) processor. This unique system offers the user a wide variety of options for real time display, analysis, and recording of thermal scenes. The design, performance, and special features of the TVS-8000 Thermal Video System will be discussed.

Forsthoefel, John J.; Toft, John B.; Furuichi, Hisaaki; Komatsubara, Shigeyuki; Sema, Akira

1994-07-01

288

High-sensitivity temperature sensor based on highly-birefringent microfiber  

NASA Astrophysics Data System (ADS)

We demonstrate an ultrasensitive temperature sensor by sealing a highly-birefringent microfiber into an alcoholinfiltrated copper capillary. With a Sagnac loop configuration, the interferometric spectrum is strongly dependent on the external refractive index (RI) with sensitivity of 36800nm/RIU around RI=1.356. As mainly derived from the ultrahigh RI sensitivity, the temperature response can reach as high as -14.72 nm/°C in the range of 30.9-36.9 °C. The measured response time is ~8s, as determined by the heat-conducting characteristic of the device and the diameter of the copper capillary. Our sensor is featured with low cost, easy fabrication and robustness.

Sun, Li-Peng; Li, Jie; Jin, Long; Gao, Shuai; Tian, Zhuang; Ran, Yang; Guan, Bai-Ou

2013-09-01

289

SML resist processing for high-aspect-ratio and high-sensitivity electron beam lithography  

NASA Astrophysics Data System (ADS)

A detailed process characterization of SML electron beam resist for high-aspect-ratio nanopatterning at high sensitivity is presented. SML contrast curves were generated for methyl isobutyl ketone (MIBK), MIBK/isopropyl alcohol (IPA) (1:3), IPA/water (7:3), n-amyl acetate, xylene, and xylene/methanol (3:1) developers. Using IPA/water developer, the sensitivity of SML was improved considerably and found to be comparable to benchmark polymethylmethacrylate (PMMA) resist without affecting the aspect ratio performance. Employing 30-keV exposures and ultrasonic IPA/water development, an aspect ratio of 9:1 in 50-nm half-pitch dense grating patterns was achieved representing a greater than two times improvement over PMMA. Through demonstration of 25-nm lift-off features, the pattern transfer performance of SML is also addressed.

Mohammad, Mohammad Ali; Dew, Steven K.; Stepanova, Maria

2013-03-01

290

SML resist processing for high-aspect-ratio and high-sensitivity electron beam lithography.  

PubMed

A detailed process characterization of SML electron beam resist for high-aspect-ratio nanopatterning at high sensitivity is presented. SML contrast curves were generated for methyl isobutyl ketone (MIBK), MIBK/isopropyl alcohol (IPA) (1:3), IPA/water (7:3), n-amyl acetate, xylene, and xylene/methanol (3:1) developers. Using IPA/water developer, the sensitivity of SML was improved considerably and found to be comparable to benchmark polymethylmethacrylate (PMMA) resist without affecting the aspect ratio performance. Employing 30-keV exposures and ultrasonic IPA/water development, an aspect ratio of 9:1 in 50-nm half-pitch dense grating patterns was achieved representing a greater than two times improvement over PMMA. Through demonstration of 25-nm lift-off features, the pattern transfer performance of SML is also addressed. PMID:23531370

Mohammad, Mohammad Ali; Dew, Steven K; Stepanova, Maria

2013-01-01

291

Single Cell Proteomics with Ultra-High Sensitivity Mass Spectrometry  

SciTech Connect

This project was a joint LDRD project between PAT, CMS and NAI with the objective to develop an instrument that analyzes the biochemical composition of single cells in real-time using bioaerosol mass spectrometry (BAMS) combined with advanced laser desorption and ionization techniques. Applications include both biological defense, fundamental cell biology and biomedical research. BAMS analyzes the biochemical composition of single, micrometer-sized particles (such as bacterial cells or spores) that can be directly sampled from air or a suspension. BAMS is based on an earlier development of aerosol time of flight mass spectrometry (ATOFMS) by members of our collaboration [1,2]. Briefly, in ATOFMS and BAMS aerosol particles are sucked directly from the atmosphere into vacuum through a series of small orifices. As the particles approach the ion source region of the mass spectrometer, they cross and scatter light from two CW laser beams separated by a known distance. The timing of the two bursts of scattered light created by each ''tracked'' particle reveals the speed, location and size of the particle. This information then enables the firing of a high-intensity laser such that the resulting laser pulse desorbs and ionizes molecules from the tracked particle just as it reaches the center of the ion source region. The full spectrum of ions is then measured using a time-of-flight mass spectrometer. The ability to rapidly analyze individual particles is clearly applicable to the rapid detection of aerosolized biological warfare agents so long as agent particles can be made to produce mass spectra that are distinct from the spectra of harmless background particles. The pattern of ions formed is determined by the properties of the laser pulse, the particle, and, in aerosol matrix-assisted laser desorption/ionization (MALDI), also the MALDI matrix used. As a result, it is critical that the properties of the laser pulses used for desorption and ionization be carefully chosen. The work on this LDRD project was centered on demonstrating the usefulness of mass signatures obtained by BAMS for identification of biological agents and discrimination from background. To accomplish this goal this work also included a thorough study of the origins of the observed mass signatures (i.e. peak identification and dependence on bacterial growth conditions) and their dependence on laser parameters. Such a fundamental understanding of the mass signatures and their dependence on laser parameters is required for optimizing the desorption/ionization process and the bioaerosol mass spectrometer in order to increase the sensitivity and specificity of this method for practical CBNP applications.

Frank, M

2005-02-16

292

A high-sensitivity push-pull magnetometer  

NASA Astrophysics Data System (ADS)

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 .

Breschi, E.; Gruji?, Z. D.; Knowles, P.; Weis, A.

2014-01-01

293

A High-Sensitivity Current Sensor Utilizing CrNi Wire and Microfiber Coils  

PubMed Central

We obtain an extremely high current sensitivity by wrapping a section of microfiber on a thin-diameter chromium-nickel wire. Our detected current sensitivity is as high as 220.65 nm/A2 for a structure length of only 35 ?m. Such sensitivity is two orders of magnitude higher than the counterparts reported in the literature. Analysis shows that a higher resistivity or/and a thinner diameter of the metal wire may produce higher sensitivity. The effects of varying the structure parameters on sensitivity are discussed. The presented structure has potential for low-current sensing or highly electrically-tunable filtering applications.

Xie, Xiaodong; Li, Jie; Sun, Li-Peng; Shen, Xiang; Jin, Long; Guan, Bai-ou

2014-01-01

294

Pajarito Monitor: a high-sensitivity monitoring system for highly enriched uranium  

SciTech Connect

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.

Fehlau, P.E.; Coop, K.; Garcia, C. Jr.; Martinez, J.

1984-01-01

295

Improvement in the light sensitivity of the ultrahigh-speed high-sensitivity CCD with a microlens array  

NASA Astrophysics Data System (ADS)

We are advancing the development of ultrahigh-speed, high-sensitivity CCDs for broadcast use that are capable of capturing smooth slow-motion videos in vivid colors even where lighting is limited, such as at professional baseball games played at night. We have already developed a 300,000 pixel, ultrahigh-speed CCD, and a single CCD color camera that has been used for sports broadcasts and science programs using this CCD. However, there are cases where even higher sensitivity is required, such as when using a telephoto lens during a baseball broadcast or a high-magnification microscope during science programs. This paper provides a summary of our experimental development aimed at further increasing the sensitivity of CCDs using the light-collecting effects of a microlens array.

Hayashida, T.,; Yonai, J.; Kitamura, K.; Arai, T.; Kurita, T.; Tanioka, K.; Maruyama, H.; Etoh, T. Goji; Kitagawa, S.; Hatade, K.; Yamaguchi, T.; Takeuchi, H.; Iida, K.

2008-02-01

296

DNA Biosensor with High Sensitivity Amplified by Gold Nanoparticles  

Microsoft Academic Search

A biosensor based on quartz crystal microbalance (QCM) using 50 nm gold nanoparticles as the amplification probe for DNA detection was reported in this paper. It had been found that a DNA detection sensitivity of 10-14 M could be obtained, which was higher than what has been ever reported using the same method. In the curve of weight increase (?m)

H. Q. Zhao; L. Lin; J. R. Li; J. A. Tang; M. X. Duan; L. Jiang

2001-01-01

297

High Temperature Induced Antibiotic Sensitivity in Pseudomonas aeruginosa.  

National Technical Information Service (NTIS)

Pseudomonas aeruginosa, which is resistant to a wide variety of antibiotics, becomes sensitive to several of these antibiotics when grown and tested at 46 deg C. Cell wall antibiotics such as pencillin-G and ampicillin are only effective when added to cel...

A. R. Bhatti K. Kumar C. Stobo J. M. Ingram

1984-01-01

298

High-Sensitivity Pressure Gauge Coupling Two Spoon Gauges  

Microsoft Academic Search

A somewhat different arrangement of spoon or sickle gages is discussed ; which is more easily constructed. The sensitivity of the modified arrangement is ; about 3 whereas for the unmodified arrangement it is about 0.01 to 0.1 (defined ; as mm deflection per mm of Hg pressure differential). (B.O.G.);

R. R. Monchamp; E. Bannister; F. A. Cotton

1959-01-01

299

High-sensitivity and wide-directivity ultrasound detection using high Q polymer microring resonators  

PubMed Central

Small size ultrahigh Q polymer microrings working at near visible wavelength have been experimentally demonstrated as ultralow noise ultrasound detectors with wide directivity at high frequencies (>20 MHz). By combining a resist reflow and a low bias continuous etching and passivation process in mold fabrication, imprinted polymer microrings with drastically improved sidewall smoothness were obtained. An ultralow noise-equivalent pressure of 21.4 Pa over 1–75 MHz range has been achieved using a fabricated detector of 60 ?m diameter. The device’s wide acceptance angle with high sensitivity considerably benefits ultrasound-related imaging.

Ling, Tao; Chen, Sung-Liang; Guo, L. Jay

2011-01-01

300

Miniature highly-birefringent microfiber loop with extremely-high refractive index sensitivity.  

PubMed

A miniature polarimetric interferometer with the twist of a highly-birefringent microfiber is demonstrated. Good transmission spectral characteristics, which are co-governed by the birefringence and the twist degree of the microfiber, are investigated. The structure exhibits extremely-high sensitivity of around 24,373 nm per refractive-index unit and excellent temperature stability of better than 0.005 nm/°C. Featured with compactness, reconfigurability, stability, robustness, and compatibility with other fiberized components, our device has potential in tunable filtering, sensing, multi-wavelength lasing, and etc. PMID:22535109

Sun, Lipeng; Li, Jie; Tan, Yanzhen; Shen, Xiang; Xie, Xiaodong; Gao, Shuai; Guan, Bai-Ou

2012-04-23

301

Theoretical analysis of highly sensitive prism based surface plasmon resonance sensor with indium tin oxide  

NASA Astrophysics Data System (ADS)

An extremely sensitive silica glass prism based SPR sensor with indium tin oxide (ITO) layer is presented and theoretically analyzed. The sensitivity of the sensor enhances with the increase in the thickness of ITO layer. With optimized values of thickness of ITO layer and incident wavelength to be 50 nm and 1600 nm, respectively, the proposed sensor offers high sensitivity of 164°/RIU.

Sharma, Navneet K.; Yadav, Swati; Sajal, Vivek

2014-05-01

302

The strain-rate sensitivity of high-strength high-toughness steels.  

SciTech Connect

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.

Dilmore, M.F. (AFRL/MNMW, Eglin AFB, FL); Crenshaw, Thomas B.; Boyce, Brad Lee

2006-01-01

303

Development of a rapid screening method to determine primary aromatic amines in kitchen utensils using direct analysis in real time mass spectrometry (DART-MS).  

PubMed

Primary aromatic amines (PAAs) are a group of substances with undesirable health effects, that are used in a variety of commercial products. Several recent studies, using a number of screening and confirmatory methods, have reported the migration of PAAs from some kitchen utensils into acetic acid 3% (w/v). Many of these methods require significant sample preparation, therefore the aim of this work was to determine if direct analysis in real time mass spectrometry (DART-MS) could be utilised as a rapid screening tool for the determination of PAAs in kitchen utensils. DART-MS results from direct analysis of the utensil have been compared with results of PAA migration by ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method. The UPLC-MS/MS method had excellent linearity, appropriate sensitivity (LOD ? 1.5 µg L(-1); LOQ ? 4.5 µg L(-1)), repeatability from 2.4 to 13.2% and acceptable recoveries. DART-MS results were in good agreement with UPLC-MS/MS data, with 100% of non-compliant (PAA positive) samples successfully identified by DART-MS. PMID:24256323

Paseiro-Cerrato, R; Noonan, G O; Begley, T H

2014-01-01

304

Extremely high frequency sensitivity in a 'simple' ear.  

PubMed

An evolutionary war is being played out between the bat, which uses ultrasonic calls to locate insect prey, and the moth, which uses microscale ears to listen for the approaching bat. While the highest known frequency of bat echolocation calls is 212 kHz, the upper limit of moth hearing is considered much lower. Here, we show that the greater wax moth, Galleria mellonella, is capable of hearing ultrasonic frequencies approaching 300 kHz; the highest frequency sensitivity of any animal. With auditory frequency sensitivity that is unprecedented in the animal kingdom, the greater wax moth is ready and armed for any echolocation call adaptations made by the bat in the on-going bat-moth evolutionary war. PMID:23658005

Moir, Hannah M; Jackson, Joseph C; Windmill, James F C

2013-08-23

305

High-resolution, high-sensitivity NMR of nanolitre anisotropic samples by coil spinning.  

PubMed

Nuclear magnetic resonance (NMR) can probe the local structure and dynamic properties of liquids and solids, making it one of the most powerful and versatile analytical methods available today. However, its intrinsically low sensitivity precludes NMR analysis of very small samples-as frequently used when studying isotopically labelled biological molecules or advanced materials, or as preferred when conducting high-throughput screening of biological samples or 'lab-on-a-chip' studies. The sensitivity of NMR has been improved by using static micro-coils, alternative detection schemes and pre-polarization approaches. But these strategies cannot be easily used in NMR experiments involving the fast sample spinning essential for obtaining well-resolved spectra from non-liquid samples. Here we demonstrate that inductive coupling allows wireless transmission of radio-frequency pulses and the reception of NMR signals under fast spinning of both detector coil and sample. This enables NMR measurements characterized by an optimal filling factor, very high radio-frequency field amplitudes and enhanced sensitivity that increases with decreasing sample volume. Signals obtained for nanolitre-sized samples of organic powders and biological tissue increase by almost one order of magnitude (or, equivalently, are acquired two orders of magnitude faster), compared to standard NMR measurements. Our approach also offers optimal sensitivity when studying samples that need to be confined inside multiple safety barriers, such as radioactive materials. In principle, the co-rotation of a micrometre-sized detector coil with the sample and the use of inductive coupling (techniques that are at the heart of our method) should enable highly sensitive NMR measurements on any mass-limited sample that requires fast mechanical rotation to obtain well-resolved spectra. The method is easy to implement on a commercial NMR set-up and exhibits improved performance with miniaturization, and we accordingly expect that it will facilitate the development of novel solid-state NMR methodologies and find wide use in high-throughput chemical and biomedical analysis. PMID:17554303

Sakellariou, D; Le Goff, G; Jacquinot, J-F

2007-06-01

306

High-sensitivity observations of HD 44179 - The Red Rectangle  

Microsoft Academic Search

The Red Rectangle (= HD 44179) was observed with the VLA at 1.465 and 4.885 GHz in search of nonthermal radio emission similar to that of SS433. To very sensitive limits, there is no radio emission from the Red Rectangle at these frequencies. If it were an SS433-like object, then its radio-emission intensity is less than 10 to the 6.5

B. J. Geldzahler; N. L. Cohen

1983-01-01

307

Design of High Sensitivity SOI Piezoresistive MEMS Pressure Sensor  

Microsoft Academic Search

\\u000a In this paper, the effect of the size of the piezoresistors that forms the Wheatstone bridge on sensitivity has been studied\\u000a and reported. There are four resistors implanted on the diaphragm in such a way that two of them sense the tensile stress\\u000a (Group I) and the other two senses the compressive stresses (Group II). The structure of this MEMS

T. Pravin Raj; S. B. Burje; R. Joseph Daniel

308

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

Microsoft Academic Search

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

Alessio Stefani; Søren Andresen; Wu Yuan; Nicolai Herholdt-Rasmussen; Ole Bang

2012-01-01

309

High-sensitivity fiber optic planar ultrasonic microphone  

NASA Astrophysics Data System (ADS)

We describe the design and performance of a novel planar ultrasonic fiber sensor for detection of air acoustic signals. The sensor is formed from a potted single layer of spirally wound optical fiber, and configured such that the static backing pressure can be varied. Experimentally we demonstrate normalized sensitivities ((Delta) (phi) /(phi) (Delta) P) of -295 to -265 dB re. 1 (mu) Pa-1.

Knudsen, Sverre; Yurek, A. M.; Tveten, Alan B.; Dandridge, Anthony D.

1994-09-01

310

Highly refractive index sensitive femtosecond laser inscribed long period gratings  

NASA Astrophysics Data System (ADS)

The distinct behaviour of femtosecond laser inscribed long period gratings, with a non-uniform index perturbation within the optical fibre core, has been studied experimentally. The non-uniform laser-induced perturbation results in light coupling from the core mode to a greater number of cladding modes than is the case with their UV laser inscribed counterparts, and this is made evident from the surrounding refractive index (SRI) grating response. Femtosecond inscribed long period gratings are shown to simultaneously couple to multiple sets of cladding modes. A 400?m LPG is shown to result in attenuation peaks that have both blue and red wavelength shifts over a 1250nm to 1700nm wavelength range. This gives rise to SRI sensitivities far greater than anything achievable by monitoring a single attenuation peak. The maximum sensitivity produced by monitoring a single attenuation peak was 1106nm/RIU, whereas monitoring opposing wavelength shifts resulted in a significantly improved sensitivity of 1680nm/RIU.

Davies, Edward; Kalli, Kyriacos; Koutsides, Charalambos; Zhang, Lin

2011-05-01

311

Antibody desensitization therapy in highly sensitized lung transplant candidates.  

PubMed

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. PMID:24666831

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

312

High sensitivity gas sensor based on high-Q suspended polymer photonic crystal nanocavity  

NASA Astrophysics Data System (ADS)

We present high-sensitivity, multi-use optical gas sensors based on a one-dimensional photonic crystal cavity. These devices are implemented in versatile, flexible polymer materials which swell when in contact with a target gas, causing a measurable cavity length change. This change causes a shift in the cavity resonance, allowing precision measurements of gas concentration. We demonstrate suspended polymer nanocavity sensors and the recovery of sensors after the removal of stimulant gas from the system. With a measured quality factor exceeding 104, we show measurements of gas concentration as low as 600 parts per million (ppm) and an experimental sensitivity of 10 ppm; furthermore, we predict detection levels in the parts-per-billion range for a variety of gases.

Clevenson, Hannah; Desjardins, Pierre; Gan, Xuetao; Englund, Dirk

2014-06-01

313

A high molar extinction coefficient charge transfer sensitizer and its application in dye-sensitized solar cell  

Microsoft Academic Search

A high molar extinction coefficient charge transfer sensitizer tetrabutylammonium [Ru(4,-carboxylic acid-4?-carboxylate-2,2?-bipyridine)(4,4?-di-(2-(3,6-dimethoxyphenyl)ethenyl)-2,2?-bipyridine)(NCS)2], is developed which upon anchoring onto nanocrystalline TiO2 films exhibit superior power conversion efficiency compared to the standard sensitizer bistetrabutylammonium cis-dithiocyanatobis(4,4?-dicarboxylic acid-2,2?-bipyridine)ruthenium(II) (N719). The new sensitizer anchored TiO2 films harvest visible light very efficiently over a large spectral range and produce a short-circuit photocurrent density of 18.84mA\\/cm2, open-circuit voltage

T. Bessho; Le Cevey; S. Ito; C. Klein; F. De Angelis; S. Fantacci; P. Comte; P. Liska; H. Imai; M. Graetzel

2007-01-01

314

Highly sensitive ultrafast pulse characterization using hydrogenated amorphous silicon waveguides.  

PubMed

We experimentally demonstrate frequency resolved optical gating (FROG) via four-wave mixing (FWM) in ultrahigh nonlinearity hydrogenated amorphous silicon waveguides. We demonstrate FROG characterization using a FWM architecture that mimics second harmonic generation (SHG) FROG for pulsewidths as low as 360 fs. Additionally, we demonstrate for the first time a FWM architecture analogous to third harmonic generation (THG) FROG and validate its ability to overcome the direction of time ambiguity of the SHG-like architecture. Both architectures allow for sensitivities suitable for future telecommunications signals. PMID:24514697

Petrillo, Keith G; Wang, Ke-Yao; Foster, Amy C; Foster, Mark A

2013-12-16

315

A low-power, high-sensitivity micromachined optical magnetometer  

NASA Astrophysics Data System (ADS)

We demonstrate an optical magnetometer based on a microfabricated 87Rb vapor cell in a micromachined silicon sensor head. The alkali atom density in the vapor cell is increased by heating the cell with light brought to the sensor through an optical fiber, and absorbed by colored filters attached to the cell windows. A second fiber-optically coupled beam optically pumps and interrogates the atoms. The magnetometer operates on 140 mW of heating power and achieves a sensitivity below 20 fT/?Hz throughout most of the frequency band from 15 Hz to 100 Hz. Such a sensor can measure magnetic fields from the human heart and brain.

Mhaskar, R.; Knappe, S.; Kitching, J.

2012-12-01

316

High sensitivity 810 GHz SIS receivers at AST/RO  

NASA Astrophysics Data System (ADS)

In November 2003 the heterodyne receivers WANDA (polarization diplexed 492/810 GHz) and PoleSTAR (2x2 810 GHz array) of AST/RO (Antarctic Submillimeter Telescope and Remote Observatory, located at the South Pole) were upgraded with new 810 GHz SIS (Superconductor-Insulator-Superconductor) waveguide mixers from KOSMA. Profiting from device development for the HIFI (Heterodyne Instrument for the Far-Infrared) Band 2 SIS mixers of the Herschel Space Observatory, a factor of approx. 2 improvement in receiver noise temperature (from 1100 K to 550 K DSB) was achieved with WANDA. The SIS mixer devices employ low-loss NbTiN-Al tuning circuits and are fabricated using electron beam lithographic junction area definition and CMP (Chemical Mechanical Polishing) of the tuning circuit dielectric. With the South Pole being one of the best possible sites for ground-based submillimeter astronomy, the 1.7 m telescope currently makes AST/RO well suited for sensitive, large scale spectral line mapping at 810 GHz. Low atmospheric opacity (tau < 1) and, consequently, very low system noise temperatures (< 3000 K) are regularly achieved at 810 GHz, making AST/RO an extremely sensitive observatory at these frequencies. "First light" astronomical measurements made with the upgraded 810 GHz channel of WANDA towards the galactic HII region NGC 3576 in CO J=7-6 (806.65 GHz) and the neutral carbon [CI] 3P2-3P1 (809.3 GHz) lines are presented.

Pütz, Patrick; Glenz, Stefan; Teipen, Rafael; Tils, Thomas; Honingh, Netty; Jacobs, Karl; Hedden, Abigail; Kulesa, Craig; Groppi, Christopher E.; Walker, Christopher K.

2004-10-01

317

Ammonium dithionate- a new material for highly sensitive EPR dosimetry.  

PubMed

Polycrystalline ammonium dithionate has been examined for its radiation response in the low dose range (<5Gy) using EPR technique. The SO(3)(-) radical ion was detected as a single EPR line with a peak-to-peak derivative width of ca. 0.44mT in irradiated samples and its intensity was found to vary linearly with dose. At equal and moderate settings of microwave power and modulation amplitude ammonium dithionate was at least seven times more sensitive than l-alanine which is the most common EPR dosimeter standard. Pulse experiments were performed on the powder samples to obtain the longitudinal relaxation time. These and microwave saturation experiments served to indicate the optimal microwave power to be applied during measurements as an EPR dosimeter for best sensitivity of this material. It is thus claimed that ammonium dithionate has excellent potential to become an EPR dosimeter with a low limit of the measurable dose for cases where tissue equivalence is not required or can be corrected for. PMID:17433765

Danilczuk, M; Gustafsson, H; Sastry, M D; Lund, E; Lund, A

2008-01-01

318

Novel high sensitivity thermal managed eclipse Z-scan technique  

NASA Astrophysics Data System (ADS)

The field of Nonlinear Optics has provided many techniques to characterize photonic materials. The Z-scan method is a well estabileshed technique that exploits front wave distortions of the light beam to determine the nonlinear properties of optical materials. Several variations of the methods have been developed, as the eclipse Z-scan that can provide up to two orders of magnitude higher sensitivity than the original Z-scan set-up. We report a new variation of the Z-scan method to characterize the third-order optical nonlinearity of photonic materials. By exploiting the combination of the eclipse Z-scan with thermal nonlinearity management, we demonstrate an improvement in sensitivity and flexibility of the method to simultaneously characterize the thermal and nonthermal nonlinearity of optical materials. The method is demonstrated by measuring the nonlinear refractive index in CS2, SiO2 and H2O as standard materials, and also of a biomaterial, the amino acid Tryptophan in water solution, using the same experimental set up based on a femtosecond Ti-saphire laser operating at 76MHz repetition rate.

Gomes, Anderson S. L.; Falcão Filho, Edilson L.; de Araújo, Cid B.; Rativa, Diego; de Araujo, Renato E.

2007-03-01

319

High sensitivity magnetic head for a shaft torque sensor  

NASA Astrophysics Data System (ADS)

The structure of a magnetic head used for torque sensing is investigated to seek higher sensitivity with low power consumption. The magnetic head investigated consists of two figure-eight coils embedded in a ferrite core. Torque applied to a magnetostrictive steel shaft makes the magnetic coupling between two coils in the head change positively or negatively depending on the sign and the strength of torque. Two structures, the square shape and the diagonal shape, are analyzed in terms of sensitivity and compared to our previous structure, the circle shape, which is an intermediate of the two in shape. It was found that the diagonal structure is the best choice. With this structure using a 14.6 mm square ferrite core, the applied torque is stably detected with 0.1 W power consumption (excitation condition: 60 kHz, 0.1 A) from a case-hardened steel shaft with an air gap 0.5 mm between head and shaft.

Sasada, I.; Akinaga, M.

2002-05-01

320

Ultra-high sensitive and high resolution optical coherence tomography using a laser induced electromagnetic dipole  

NASA Astrophysics Data System (ADS)

Utilizing an optical coherence tomography measurement, we have developed a technique that actively uses a dielectric response due to an induced dipole moment caused by a mode-locked pulsed laser light source. Irradiated laser light in the material induces a photo-induced electric dipole resulting in a refractive index change for its strong electric field. Using this technique, we obtained a highly sensitive fundus retina tomogram of a human eye in vivo with a resolution of 1.3 ?m by single scanning for 20 ms using 8 fs mode-locked pulse laser light with a 350 nm spread spectrum.

Kuroda, Hiroto; Baba, Motoyoshi; Suzuki, Masayuki; Yoneya, Shin

2013-09-01

321

High-precision high-sensitivity clock recovery circuit for a mobile payment application  

NASA Astrophysics Data System (ADS)

This paper presents a fully integrated carrier clock recovery circuit for a mobile payment application. The architecture is based on a sampling-detection module and a charge pump phase locked loop. Compared with clock recovery in conventional 13.56 MHz transponders, this circuit can recover a high-precision consecutive carrier clock from the on/off keying (OOK) signal sent by interrogators. Fabricated by a SMIC 0.18-?m EEPROM CMOS process, this chip works from a single power supply as low as 1.5 V Measurement results show that this circuit provides 0.34% frequency deviation and 8 mV sensitivity.

Lichong, Sun; Wenliang, Ren; Na, Yan; Hao, Min

2011-05-01

322

High-sensitivity observations of HD 44179 - The Red Rectangle  

NASA Astrophysics Data System (ADS)

The Red Rectangle (= HD 44179) was observed with the VLA at 1.465 and 4.885 GHz in search of nonthermal radio emission similar to that of SS433. To very sensitive limits, there is no radio emission from the Red Rectangle at these frequencies. If it were an SS433-like object, then its radio-emission intensity is less than 10 to the 6.5 power that of SS433, which contradicts the similarity in energetics seen in the 'Doppler' broadened optical line profile of the Red Rectangle. However, the lack of radio emission is consistent with the presence of a bipolar nebula, which would have a 'pressure' broadened profile.

Geldzahler, B. J.; Cohen, N. L.

1983-08-01

323

Highly sensitive humidity sensing properties of carbon quantum dots films  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? A humidity sensing device was fabricated based on carbon quantum dots (CQDs) films. ? The conductivity of the CQDs films shows a linear and rapid response to atmosphere humidity. ? The humidity sensing property was due to the hydrogen bonds between the functional groups on CQDs. -- Abstract: We reported the fabrication of a humidity sensing device based on carbon quantum dots (CQDs) film. The conductivity of the CQDs film has a linear and rapid response to relative humidity, providing the opportunity for the fabrication of humidity sensing devices. The mechanism of our humidity sensor was proposed to be the formation of hydrogen bonds between carbon quantum dots and water molecules in the humidity environment, which significantly promote the electrons migration. In a control experiment, this hypothesis was confirmed by comparing the humidity sensitivity of candle soot (i.e. carbon nanoparticles) with and without oxygen containing groups on the surfaces.

Zhang, Xing; Ming, Hai; Liu, Ruihua; Han, Xiao [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China)] [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China)] [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China)] [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou (China); Zhang, Yonglai, E-mail: yonglaizhang@jlu.edu.cn [Center of Super-Diamond and Advanced Films (COSDAF), Department of Physics and Materials Science, City University of Hong Kong, Hong Kong (China) [Center of Super-Diamond and Advanced Films (COSDAF), Department of Physics and Materials Science, City University of Hong Kong, Hong Kong (China); State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)

2013-02-15

324

Type 2 ryanodine receptors are highly sensitive to alcohol.  

PubMed

Exposure to ethanol levels reached in circulation during alcohol intoxication (>10mM) constricts cerebral arteries in rats and humans. Remarkably, targets and mechanisms underlying this action remain largely unidentified. Artery diameter is regulated by myocyte Ca(2+) sparks, a vasodilatory signal contributed to by type 2 ryanodine receptors (RyR2). Using laser confocal microscopy in rat cerebral arteries and bilayer electrophysiology we unveil that ethanol inhibits both Ca(2+) spark and RyR2 activity with IC50<20mM, placing RyR2 among the ion channels that are most sensitive to ethanol. Alcohol directly targets RyR2 and its lipid microenvironment, leading to stabilization of RyR2 closed states. PMID:24631538

Ye, Yanping; Jian, Kuihuan; Jaggar, Jonathan H; Bukiya, Anna N; Dopico, Alex M

2014-05-01

325

A new compact, high sensitivity neutron imaging system.  

PubMed

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(9)-10(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 × 10(10). The resolution of this image was 54 ?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 (60)Co ?-ray source. The calibration showed that the signal-to-noise ratio could be improved by using raw binning detection. PMID:23126952

Caillaud, T; Landoas, O; Briat, M; Rossé, B; Thfoin, I; Philippe, F; Casner, A; Bourgade, J L; Disdier, L; Glebov, V Yu; Marshall, F J; Sangster, T C; Park, H S; Robey, H F; Amendt, P

2012-10-01

326

A new compact, high sensitivity neutron imaging system  

NASA Astrophysics Data System (ADS)

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 (109-1010 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 × 1010. The resolution of this image was 54 ?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 60Co ?-ray source. The calibration showed that the signal-to-noise ratio could be improved by using raw binning detection.

Caillaud, T.; Landoas, O.; Briat, M.; Rossé, B.; Thfoin, I.; Philippe, F.; Casner, A.; Bourgade, J. L.; Disdier, L.; Glebov, V. Yu.; Marshall, F. J.; Sangster, T. C.; Park, H. S.; Robey, H. F.; Amendt, P.

2012-10-01

327

Carbon nanotube quantum dots as highly sensitive THz spectrometers  

NASA Astrophysics Data System (ADS)

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).

Rinzan, Mohamed; Jenkins, Greg; Drew, Dennis; Shafranjuk, Serhii; Barbara, Paola

2012-02-01

328

DEVELOPMENT AND CHARACTERIZATION OF HIGH-SENSITIVITY BIOINSPIRED ARTIFICIAL HAIRCELL SENSOR  

Microsoft Academic Search

We report the development of a high sensitivity artificial haircell (AHC) sensor that employs high aspect-ratio cilium (up to 700?m tall) made of SU-8 epoxy and silicon piezoresistive strain sensors. In this work, we demonstrate the application of the artificial haircell for underwater flow sensing. For device characterization, we have performed deflection testing, resonant frequency testing, sensitivity threshold testing and

Nannan Chen; Jack Chen; Jonathan Engel; Saunvit Pandya; Craig Tucker; Chang Liu

329

High sensitive surface micromachined out of plane tunneling accelerometers with low-g resolution  

Microsoft Academic Search

The paper presents design, fabrication and performance analysis of out-of-plane tunneling accelerometers of different configurations. The tunneling structures have been realized by standard surface micromachined process. This work also records the relative performance of the devices to achieve high sensitivity, high dynamic range and low cross axis sensitivity for sub dasiagpsila measurement at relatively low actuation voltage.

Srijita Patra; Tarun K Bhattacharyya

2009-01-01

330

Highly sensitive tunneling accelerometer for low actuation voltage operation  

Microsoft Academic Search

In this work an attempt has been made to develop an accelerometer based on the principle of electron tunneling. Since the tunneling current is exponentially related to the displacement of the tunneling tip attached with beam, this accelerometer consummates high resolution and especially high dynamic range. Apart from increasing the dynamic range, the actuation voltage is reduced by optimizing the

Srijita Patra; Tarun K Bhattacharyya

2010-01-01

331

High counting rate, two-dimensional position sensitive timing RPC  

NASA Astrophysics Data System (ADS)

Motivated by the requirements of the next generation experiments in terms of very good time and position resolution in high counting rate and multiplicity environment, a new architecture of differential, strip structure, symmetric, multi gap timing RPC was developed. The results on efficiency, time resolution, position resolution and performance in high counting rate environment using low resistivity glass electrodes are reported.

Petrovici, M.; Petri?, M.; Simion, V.; Barto?, D.; Caragheorgheopol, G.; Constantin, F.; R?dulescu, L.; Adamczewski-Musch, J.; Deppner, I.; Doroud, K.; Herrmann, N.; Linev, S.; Loizeau, P.; Williams, M. C. S.

2012-11-01

332

Highly Sensitive Three Dimensional Measurement Using Ultrashort Pulse Fiber Laser and Fiber Interferometer  

Microsoft Academic Search

Three dimensional measurement system with high sensitivity of 99 dB and high longitudinal resolution of 10 ?m is demonstrated using ultrashort pulse fiber laser and fiber interferometer. Precise image is obtained from 1.5 m distance.

N. Nishizawa; T. Ohta; T. Goto

2005-01-01

333

Highly sensitive glucose biosensor based on Au-Ni coaxial nanorod array having high aspect ratio.  

PubMed

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 ?m. 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 ?M-27.5mM with a detection limit of 5.5?M and a very high sensitivity of 769.6 ?A 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. PMID:24495482

Hsu, Che-Wei; Wang, Gou-Jen

2014-06-15

334

High Order Effects in Cross Section Sensitivity Analysis.  

National Technical Information Service (NTIS)

Two types of high order effects associated with perturbations in the flux shape are considered: Spectral Fine Structure Effects (SFSE) and non-linearity between changes in performance parameters and data uncertainties. SFSE are investigated in Part I usin...

E. Greenspan Y. Karni D. Gilai

1978-01-01

335

Highly sensitive homogenous chemiluminescence immunoassay using gold nanoparticles as label.  

PubMed

Homogeneous immunoassay is becoming more and more attractive for modern medical diagnosis because it is superior to heterogeneous immunoassay in sample and reagent consumption, analysis time, portability and disposability. Herein, a universal platform for homogeneous immunoassay, using human immunoglobulin G (IgG) as a model analyte, has been developed. This assay relies upon the catalytic activity of gold nanoparticles (AuNPs) on luminol-AgNO3 chemiluminescence (CL) reaction. The immunoreaction of antigen and antibody can induce the aggregation of antibody-functionalized AuNPs, and after aggregation the catalytic activity of AuNPs on luminol-AgNO3 CL reaction is greatly enhanced. Without any separation steps, a CL signal is generated upon addition of a trigger solution, and the CL intensity is directly correlated to the quantity of IgG. The detection limit of IgG was estimated to be as low as 3pg/mL, and the sensitivity was better than that of the reported AuNPs-based CL immunoassay for IgG. PMID:24835732

Luo, Jing; Cui, Xiang; Liu, Wei; Li, Baoxin

2014-10-15

336

Highly sensitive vacuum ion pump current measurement system  

DOEpatents

A vacuum system comprising: 1) an ion pump; 2) power supply; 3) a high voltage DC--DC converter drawing power from the power supply and powering the vacuum pump; 4) a feedback network comprising an ammeter circuit including an operational amplifier and a series of relay controlled scaling resistors of different resistance for detecting circuit feedback; 5) an optional power block section intermediate the power supply and the high voltage DC--DC converter; and 6) a microprocessor receiving feedback information from the feedback network, controlling which of the scaling resistors should be in the circuit and manipulating data from the feedback network to provide accurate vacuum measurement to an operator.

Hansknecht, John Christopher (Williamsburg, VA) [Williamsburg, VA

2006-02-21

337

High Sensitivity of Giardia duodenalis to Tetrahydrolipstatin (Orlistat) In Vitro  

PubMed Central

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 (IC5024h?=?2.8 µM) being more sensitive than WB-C6 (IC5024h?=?6.2 µM). The effect was significantly more potent compared to MTZ (IC5024h?=?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.

Hahn, Juliane; Seeber, Frank; Kolodziej, Herbert; Ignatius, Ralf; Laue, Michael; Aebischer, Toni; Klotz, Christian

2013-01-01

338

Silicon nanowire structures as high-sensitive pH-sensors  

NASA Astrophysics Data System (ADS)

Sensitive elements for pH-sensors created on silicon nanostructures were researched. Silicon nanostructures have been used as ion-sensitive field effect transistor (ISFET) for the measurement of solution pH. Silicon nanostructures have been fabricated by "top-down" approach and have been studied as pH sensitive elements. Nanowires have the higher sensitivity. It was shown, that sensitive element, which is made of "one-dimensional" silicon nanostructure have bigger pH-sensitivity as compared with "two-dimensional" structure. Integrated element formed from two p- and n-type nanowire ISFET ("inverter") can be used as high sensitivity sensor for local relative change [H+] concentration in very small volume.

Belostotskaya, S. O.; Chuyko, O. V.; Kuznetsov, A. E.; Kuznetsov, E. V.; Rybachek, E. N.

2012-02-01

339

High Explosive Deonation Threshold Sensitivity Due to Multiple Fragment Impacts  

Microsoft Academic Search

Fragments, bullets or projectiles can initiate a detonation in a high explosive (HE). For this to happen certain critical conditions need to be exceeded. For a given explosive, these critical conditions are the projectile velocity, the projectile size and shape, and the projectile material properties. A lot of work has been done in the area of metal shaped charge jets

V Georgevich; P Pincosy; J Chase

2004-01-01

340

Improvement of sensitivity in high-resolution ERDA  

Microsoft Academic Search

Recently, we have developed a new detector system for a magnetic spectrometer to reduce the background noise in high-resolution Rutherford backscattering spectroscopy. The detector system consists of a MCP detector for ion detection, which has a thin Mylar foil in front of the detector, and an electron detector to detect secondary electrons emitted by the ions upon impact on the

H. Hashimoto; S. Fujita; K. Nakajima; M. Suzuki; K. Sasakawa; K. Kimura

341

Differential Sensitivity Theory applied to the MESA code for high pressure interactions  

SciTech Connect

A technique called Differential Sensitivity Theory (DST) is applied to the system of equations solved by the MESA hydrocode. DST uses adjoint techniques to determine exact sensitivity derivatives, i.e., if R is a calculational result of interest (response R) and {alpha}{sub i} is a calculational input (parameter {alpha}{sub i}), then {partial_derivative}R/{partial_derivative}{alpha}{sub i} is defined as the sensitivity. The advantage of using DST is that for an n-parameter problem all n sensitivities can be obtained by integrating the solutions from only two calculations, a MESA calculation and its corresponding adjoint calculation using an Adjoint Continuum Mechanics code (ACM). This work describes the derivation and solution of the appropriate set of adjoint and sensitivity equations for the purpose of computing sensitivities for high-rate two-dimensional, multi-component, high deformation problems. As an example, results are presented for a flyer plate problem.

Maudlin, P.J.; Henninger, R.J.; Harstad, E.N.

1993-07-01

342

Effects of intrinsic magnetostriction on tube-topology magnetoelectric sensors with high magnetic field sensitivity  

NASA Astrophysics Data System (ADS)

Three quasi-one-dimensional magnetoelectric (ME) magnetic field sensors, each with a different magnetostrictive wire material, were investigated in terms of sensitivity and noise floor. Magnetostrictive Galfenol, iron-cobalt-vanadium, and iron-nickel wires were examined. Sensitivity profiles, hysteresis effects, and noise floor measurements for both optimally biased and zero-biased conditions are presented. The FeNi wire (FN) exhibits high sensitivity (5.36 mV/Oe) at bias fields below 22 Oe and an optimal bias of 10 Oe, whereas FeGa wire (FG) exhibits higher sensitivity (6.89 mW/Oe) at bias fields >22 Oe. The sensor of FeCoV wire (FC) presents relatively low sensitivity (2.12 mV/Oe), due to low magnetostrictive coefficient. Each ME tube-topology sensor demonstrates relatively high sensitivity at zero bias field, which results from a magnetic shape anisotropy and internal strain of the thin magnetostrictive wire.

Gillette, Scott M.; Fitchorov, Trifon; Obi, Ogheneyunume; Jiang, Liping; Hao, Hongbo; Wu, Shuangxia; Chen, Yajie; Harris, Vincent G.

2014-05-01

343

Use of solid-state laser with minimum amplitude noise for high-sensitivity measurements  

Microsoft Academic Search

The possibilities of an intracavity polarization-measurement method that employs the dynamic characteristics of a solid-state laser to achieve high sensitivity are considered. The theoretical sensitivity of the method is estimated to be of the order of 10 to the -11th rad for measurements of rotation of the plane of polarization. A CW Nd:YAG laser developed to achieve the theoretical sensitivity

N. M. Galaktionova; V. V. Gershun; A. A. Kalmychek; A. A. Mak; O. A. Orlov; V. I. Ustiugov

1978-01-01

344

High-sensitivity pressure sensor using a shielded polymer-coated fiber Bragg grating  

Microsoft Academic Search

We demonstrate a novel high-sensitivity pressure sensor, which is based on the use of a fiber Bragg grating (FBG) embedded in a polymer-filled metal cylinder with an opening on one side to enhance the pressure sensitivity. The measured pressure sensitivity of the fractional change in the Bragg wavelength of our experimental sensor is -3.41×10-3 MPa-1 which is approximately 1720 times

Ying Zhang; Dejun Feng; Zhiguo Liu; Zhuanyun Guo; Xiaoyi Dong; K. S. Chiang; Beatrice C. B. Chu

2001-01-01

345

Temperature-hydrostatic pressure cross-sensitivity effect in elliptical-core, highly birefringent fibers.  

PubMed

We determine the cross-sensitivity coefficient that represents the interaction between temperature and hydrostatic pressure in Corning elliptical-core, highly birefringent (HB) fiber. The measurement method we propose is especially useful to determine the cross-sensitivity effects in weakly sensitive HB fibers. The method involves registration of the residual temperature drift of thermally compensated polarimetric sensors at specially chosen values of pressure applied to the sensing fibers. PMID:21127652

Bock, W J; Urba?czyk, W

1996-11-01

346

A highly sensitive immunoassay using antibody-conjugated spherical mesoporous silica with immobilized enzymes.  

PubMed

A highly sensitive immunoassay was developed by using antibody-conjugated spherical mesoporous silica with immobilized enzymes. The higher ratio of enzyme/antibody than conventional ELISA improved both the sensitivity and dynamic range. Especially, the use of spherical mesoporous silica could achieve a limit of detection (LOD) with a sensitivity that is 20 times more than that of ELISA using amorphous silica. PMID:24402353

Eum, Ji Young; Hwang, Sang Youn; Ju, Youngjun; Shim, Jong Min; Piao, Yunxian; Lee, Jinwoo; Kim, Hak-Sung; Kim, Jungbae

2014-04-01

347

Highly Sensitive and Easy-to-Use SQUID Sensors  

Microsoft Academic Search

We have developed a novel family of low-noise superconducting quantum interference devices (SQUIDs) to cover a wide range of applications. These sensors are robust and easy to use without compromising noise performance. They are optimized for operation with our high-speed direct-coupled flux-locked loop (FLL) electronics XXF-1. For the readout of cryogenic detectors, series arrays of 16 SQUIDs with 3 nH

D.. Drung; C.. Assmann; J.. Beyer; A.. Kirste; M.. Peters; F.. Ruede; T.. Schurig

2007-01-01

348

High-Sensitivity Ionization Trace-Species Detector  

NASA Technical Reports Server (NTRS)

Features include high ion-extraction efficiency, compactness, and light weight. Improved version of previous ionization detector features in-line geometry that enables extraction of almost every ion from region of formation. Focusing electrodes arranged and shaped into compact system of space-charge-limited reversal electron optics and ion-extraction optics. Provides controllability of ionizing electron energies, greater efficiency of ionization, and nearly 100 percent ion-collection efficiency.

Bernius, Mark T.; Chutjian, Ara

1990-01-01

349

A High-Sensitivity Small-Animal PET Scanner: Development and Initial Performance Measurements  

Microsoft Academic Search

An important challenge in positron emission tomography (PET) is the development of dedicated small-animal PET (muPET) systems having high sensitivity. In this paper, we investigate the use of an opposing pair of large-area detectors having high detection efficiency and moderate depth-of-interaction resolution in a compact scanner geometry for achieving a high system sensitivity. Substantial resolution degradations created by this hardware

Chien-Min Kao; Qingguo Xie; Yun Dong; Lu Wan; Chin-Tu Chen

2009-01-01

350

Punch through float-zone silicon phototransistors with high linearity and sensitivity  

Microsoft Academic Search

In this paper, we propose, analyze and demonstrate a high-purity float-zone (FZ) silicon phototransistor operating at the punch through state with high linearity and sensitivity. Those phototransistors were fabricated on high-purity FZ silicon substrates; the dependence of the sensitivity on incident optical power and bias voltages has been investigated to light with a wavelength of 0.83 mum from a laser

C. M. Sun; D. J. Han; L. Y. Sheng; X. R. Zhang; H. J. Zhang; R. Yang; L. Zhang; B. J. Ning

2005-01-01

351

Punch through float-zone silicon phototransistors with high linearity and sensitivity  

Microsoft Academic Search

In this paper, we propose, analyze and demonstrate a high-purity float-zone (FZ) silicon phototransistor operating at the punch through state with high linearity and sensitivity. Those phototransistors were fabricated on high-purity FZ silicon substrates; the dependence of the sensitivity on incident optical power and bias voltages has been investigated to light with a wavelength of 0.83?m from a laser diode.

C. M. Sun; D. J. Han; L. Y. Sheng; X. R. Zhang; H. J. Zhang; R. Yang; L. Zhang; B. J. Ning

2005-01-01

352

Dynamics and sensitivity analysis of high-frequency conduction block  

NASA Astrophysics Data System (ADS)

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 too slow to track the high-frequency changes in membrane potential during HFS, and that the behavior of the fast sodium current was dominated by the low-frequency depolarization of the membrane. As a result, in the blocked state, only 5.4% of nodal sodium channels were found to be in the activatable state in the node closest to the blocking electrode, resulting in conduction block. Moreover, we find that the corner frequency for the persistent sodium channel activation gate corresponds to the frequency below which high-frequency stimuli of arbitrary amplitude are incapable of inducing conduction block.

Ackermann, D. Michael; Bhadra, Niloy; Gerges, Meana; Thomas, Peter J.

2011-10-01

353

Porous tungsten oxide nanoflakes for highly alcohol sensitive performance  

NASA Astrophysics Data System (ADS)

Porous tungsten oxide (WO3) nanoflakes have been synthesized by a simple and green approach in an ambient environment. As a precursor solution a polycrystalline hydrated tungstite (H2WO4.H2O) nanoparticles colloid was first prepared by pulsed-laser ablation of a tungsten target in water. The H2WO4.H2O nanoflakes were produced by 72 h aging treatment at room temperature. Finally, porous WO3 nanoflakes were synthesized by annealing at 800 °C for 4 h. Considering the large surface-to-volume ratio of porous nanoflakes, a porous WO3 nanoflake gas sensor was fabricated, which exhibits an excellent sensor response performance to alcohol concentrations in the range of 20 to 600 ppm under low working temperature. This high response was attributed to the highly crystalline and porous flake-like morphology, which leads to effective adsorption and desorption, and provides more active sites for the gas molecules' reaction. These findings showed that the porous tungsten oxide nanoflake has great potential in gas-sensing performance.

Xiao, J.; Liu, P.; Liang, Y.; Li, H. B.; Yang, G. W.

2012-10-01

354

Enhanced laboratory sensitivity to variation of the fine-structure constant using highly charged ions.  

PubMed

We study atomic systems that are in the frequency range of optical atomic clocks and have enhanced sensitivity to potential time variation of the fine-structure constant ?. The high sensitivity is due to coherent contributions from three factors: high nuclear charge Z, high ionization degree, and significant differences in the configuration composition of the states involved. Configuration crossing keeps the frequencies in the optical range despite the large ionization energies. We discuss a few promising examples that have the largest ? sensitivities seen in atomic systems. PMID:20867622

Berengut, J C; Dzuba, V A; Flambaum, V V

2010-09-17

355

Phase sensitive amplification in a highly nonlinear lead-silicate fiber.  

PubMed

We experimentally demonstrate phase-sensitive amplification in a highly nonlinear and low-dispersion lead-silicate W-type fiber. A phase-sensitive gain variation of 6 dB was observed in a 1.56-m sample of the fiber for a total input pump power of 27.7 dBm. PMID:22274505

Ettabib, Mohamed A; Jones, Liam; Kakande, Joseph; Slavík, Radan; Parmigiani, Francesca; Feng, Xian; Poletti, Francesco; Ponzo, Giorgio M; Shi, Jindan; Petrovich, Marco N; Loh, Wei H; Petropoulos, Periklis; Richardson, David J

2012-01-16

356

Design and simulation of high sensitive capacitive pressure sensor with slotted diaphragm  

Microsoft Academic Search

This paper presents a high sensitive MEMS capacitive pressure sensor for biomedical applications. Two sensor designs incorporating clamped and slotted diaphragm are implemented and compared to realize the pressure-sensitive components. The pressure sensor has been designed to measure pressures in the range of 0 to 60 mmhg that is in the range of intraocular pressure sensors. Intraocular pressure sensors are

M. Shahiri-Tabarestani; B. A. Ganji; R. Sabbaghi-Nadooshan

2012-01-01

357

Detecting hybridization of DNA by highly sensitive evanescent field etched core fiber Bragg grating sensors  

Microsoft Academic Search

Highly sensitive fiber Bragg grating sensors were developed by etching away the cladding and part of the core of the fiber and detecting the change of Bragg wavelength due to the change of index of the surrounding medium. A sensitivity of 1394 nm\\/riu was achieved when the diameter of the grating core was 3.4 ?m and the index of the

Athanasios N. Chryssis; Simarjeet S. Saini; Sang M. Lee; Hyunmin Yi; William E. Bentley; Mario Dagenais

2005-01-01

358

"Ultra-high resolution optical trap with single fluorophore sensitivity"  

PubMed Central

We present a single-molecule instrument that combines a timeshared ultra-high resolution dual optical trap interlaced with a confocal fluorescence microscope. In a demonstration experiment, individual single-fluorophore labeled DNA oligonucleotides were observed to bind and unbind to complementary DNA suspended between two trapped beads. Simultaneous with the single-fluorophore detection, coincident angstrom-scale changes in tether extension could be clearly observed. Fluorescence readout allowed us to determine the duplex melting rate as a function of force. The new instrument will enable the simultaneous measurement of angstrom-scale mechanical motion of individual DNA-binding proteins (e.g., single base pair stepping of DNA translocases) along with the detection of fluorescently labeled protein properties (e.g., internal configuration).

Comstock, Matthew J; Ha, Taekjip; Chemla, Yann R

2013-01-01

359

Method for rapid, high sensitivity tritiated water extraction  

SciTech Connect

We have developed a thermal vacuum desorption process to rapidly extract water from environmental samples for tritium analysis. Thermal vacuum desorption allows for extraction of the moisture from the sample within a few hours in a form and quantity suitable for liquid scintillation counting and allows detection of tritium at the levels of <2 Bq/L of milk, <0.5 Bq/gm of vegetation, and < 0.5 Bq/gin of soil. We developed a prototype unit that can process batches of twenty or more samples within 24 hours. Early data shows that a high percentage of water is extracted reproducibly without enrichment or depletion of the tritium content. The quench coefficient of the extracted water is low allowing for accurate, direct liquid scintillation counting. Excellent comparison has been observed with results using freeze-dry lypholization as the water extraction method.

Failor, R.; Belovodsky, L.; Gaevoy, V.; Golubev, A.

1997-04-20

360

Stretchable and highly sensitive graphene-on-polymer strain sensors  

PubMed Central

The use of nanomaterials for strain sensors has attracted attention due to their unique electromechanical properties. However, nanomaterials have yet to overcome many technological obstacles and thus are not yet the preferred material for strain sensors. In this work, we investigated graphene woven fabrics (GWFs) for strain sensing. Different than graphene films, GWFs undergo significant changes in their polycrystalline structures along with high-density crack formation and propagation mechanically deformed. The electrical resistance of GWFs increases exponentially with tensile strain with gauge factors of ~103 under 2~6% strains and ~106 under higher strains that are the highest thus far reported, due to its woven mesh configuration and fracture behavior, making it an ideal structure for sensing tensile deformation by changes in strain. The main mechanism is investigated, resulting in a theoretical model that predicts very well the observed behavior.

Li, Xiao; Zhang, Rujing; Yu, Wenjian; Wang, Kunlin; Wei, Jinquan; Wu, Dehai; Cao, Anyuan; Li, Zhihong; Cheng, Yao; Zheng, Quanshui; Ruoff, Rodney S.; Zhu, Hongwei

2012-01-01

361

Cross-sensitivity effect in temperature-compensated sensors based on highly birefringent fibers.  

PubMed

We analyzed the influence of the measurand-temperature cross-sensitivity effect on temperature stability in fiber-optic cross-spliced sensors that employ highly birefringent fibers. We show that the ratio of the measurand-temperature cross-sensitivity coefficient to the measurand first-order sensitivity determines the physical limit for temperature stability in cross-spliced sensors. Employing polarimetric as well as white-light interferometric methods, we experimentally determine a hydrostatic pressure-temperature cross-sensitivity coefficient in York bow-tie 800 fiber. From this we estimate the achievable limit for temperature stability of cross-spliced pressure sensors under environmental temperature changes. PMID:20936024

Bock, W J; Urbanczyk, W; Buczynski, R; Domanski, A W

1994-09-01

362

High-sensitivity strain sensor based on in-fiber improved Fabry-Perot interferometer.  

PubMed

We demonstrated a high-sensitivity strain sensor based on an in-fiber Fabry-Perot interferometer (FPI) with an air cavity, which was created by splicing together two sections of standard single-mode fibers. The sensitivity of this strain sensor was enhanced to 6.0??pm/?? by improving the cavity length of the FPI by means of repeating arc discharges for reshaping the air cavity. Moreover, such a strain sensor has a very low temperature sensitivity of 1.1??pm/°C, which reduces the cross sensitivity between tensile strain and temperature. PMID:24686690

Liu, Shen; Wang, Yiping; Liao, Changrui; Wang, Guanjun; Li, Zhengyong; Wang, Qiao; Zhou, Jiangtao; Yang, Kaiming; Zhong, Xiaoyong; Zhao, Jing; Tang, Jian

2014-04-01

363

Highly Sensitive Nanoparticle-based Multifunctional Biosensor for Antigen Detection  

NASA Astrophysics Data System (ADS)

Precise and selective positioning of nanoparticles gives rise to many applications where assembly of nano building blocks with different biological or chemical functionalization is necessary. One remarkable application is the simultaneous early detection of multiple biomarkers in the field of miniaturized multiplex biosensors. To enable multiplex detection of antigens, nanoparticles with various antibody coatings can be selectively assembled in trenches on different regions on a biochip so that they bind selectively to the specific antigen of interest. The presented work utilizes electric field assisted assembly techniques to assemble nanoparticles with various surface functionalization and coatings. Nanoparticles are assembled into pre-fabricated via and trench patterns generated on a PMMA coated gold surface, using electron-beam lithography. Two techniques have been developed for selective assembly of nanoparticles: sequential size-selective directed assembly and sequential site-selective assembly. Both selective assembly techniques provide fast and reproducible assembly over large areas while achieving high yield. The sequential size-selective assembly is a template-assisted technique where the selectivity is achieved by controlling the size of the nanopatterns and the size of the nanoparticles. The possibility of particle detachment and the factors affecting the sorting efficiency for this technique is studied. We show that a complete sorting can be achieved when the size of the vias is close to the diameter of the nanoparticles and the size distribution of the chosen nanoparticles do not overlap. In the site-selective assembly, the selectivity is achieved by having electrically isolated sites (regions) on the same chip. Electrophoresis is performed for each region in a step by step process. Selective assembly results, for up to four nanoparticles with various coating/functionalization are presented using the site-selective assembly technique. We use the electrophoresis technique to assemble the cancer specific anti-PSA, mAb-2C5 and CEA coated nanoparticles to show that the nanoparticle-based biochip can successfully measure low concentrations of various antigen. The principle of operation of these biosensors is the fluorescence based ELISA. Testing results of the nanoparticle-based biochips indicate very high specificity and the detection limit 200 times smaller than the commercially available devices for antigen detection, laying the foundation for early detection of various diseases. The optimized assembly of antibody coated particles and selective assembly techniques introduced in this work provide the necessary tools for fabricating a miniaturized nanoparticle-based in-vivo multiplex biosensor. The antigen detection results show the great potential for early detection of various diseases using the fabricated in-vivo device.

Siavoshi, Salome

364

(abstract) A Miniature, High-Sensitivity, Electron-Tunneling Accelerometer  

NASA Technical Reports Server (NTRS)

A prototype low-noise accelerometer has been fabricated with an electron-tunneling transducer. By measuring the tunneling current between an electrode on the proof mass and a feedback-controlled monitor electrode, very small accelerations can be detected with high responsivity. This particular prototype (10x10x1.5 mm) was designed for underwater acoustic measurement from a few hertz to 1 kHz. The measured responsivity below the fundamental device resonance at 100 Hz is roughly 1500 volts per m/s(sup 2) with a measured noise spectral density of 10(sup -6) m/s(sup 2) per root hertz or less between 30 and 300 Hz. The noise floor is controlled primarily by 1/f noise in the tunneling current although the noise floor reaches the theoretical molecular-agitation limit at 100 hertz. The responsivity and directivity of the device were measured in a standard gradient-hydrophone calibrator; the noise floor was determined in a vacuum-ionization chamber assembled from commercial off-the-shelf components; and the detailed dynamics of the proof-mass motion were examined using a heterodyne laser interferometer that was scanned across the surface and synchronously detected with respect to the excitation.

Gabrielson, Thomas B.; Rockstad, Howard K.; Tang, Tony K.

1994-01-01

365

High sensitivity optical microscope for single molecule spectroscopy studies  

NASA Astrophysics Data System (ADS)

We describe the setup and apply two algorithms for fast imaging in a sample raster scanning two photon microscope. Imaging can be performed at a rate of 1-100 lines per second with a closed loop piezo actuator, and the detection is performed via avalanche photodiodes. This allows to investigate single molecule emission with 50 ms time resolution. In a slow scanning algorithm we have implemented fluorescence fluctuation analysis by computing the photon counting histogram (PCH) on each pixel of the image. In a fast-scan acquistion method the image acquistion rate is 5 lines per second on a large field of view and high resolution(50 nm scanning step, 100×100 ?m2 field of view) and ?100 lines per second on smaller field of views with optically limited resolution (200 nm scanning step, 20×20 ?m2 field of view). This figure, which is lower than the typical value for normal confocal scanning imaging (?500 lines per second), allows nevertheless to perform imaging studies of extended samples in reasonable times for intracellular kinetics and interactions. With this setup and by means of the PCH analysis we are able to discriminate between local concentration and molecular brightness on extended samples also at the level of the single molecule.

Malengo, Gabriele; Milani, Roberto; Cannone, Fabio; Krol, Silke; Diaspro, Alberto; Chirico, Giuseppe

2004-08-01

366

HIGH SENSITIVITY FOURIER TRANSFORM NMR. INTERMOLECULAR INTERACTIONS BETWEEN ENVIRONMENTAL TOXIC SUBSTANCES AND BIOLOGICAL MACROMOLECULES  

EPA Science Inventory

This project explored the feasibility of developing new techniques for evaluation of the effects of environmental toxic materials on complex biopolymer systems using high sensitivity Fourier transform nuclear magnetic resonance (nmr) spectroscopy. Commercial instrumentation avail...

367

A highly sensitive and genetically encoded fluorescent reporter for ratiometric monitoring of quinones in living cells.  

PubMed

The transcriptional regulator QsrR is converted into a genetically encoded fluorescent probe capable of ratiometric monitoring of quinones in living cells with high sensitivity and selectivity. PMID:23903292

Ji, Quanjiang; Zhao, Boxuan Simen; He, Chuan

2013-09-21

368

Validation of a method for the targeted analysis of 96 drugs in hair by UPLC-MS/MS.  

PubMed

The method presented in this study allows the screening and quantification of 96 drugs, from different groups: opiates, amphetamines, hallucinogens, benzodiazepines, antihistamines, antidepressants, antipsychotics, barbiturates and other sedatives, muscle relaxants, etc. in hair. Drugs are extracted from 10mg of washed hair in 18h by a mixture of methanol:acetonitrile:ammonium formate (pH 5.3). Absolute recovery ranged from 70% to 106% for 75% of the analytes. The limits of detection in the low pg/mg range, may allow the detection of single dose drug exposure, with possible application in drug facilitated assaults (DFA); however, chronic use (compliance) can also be examined. The method has been fully validated for the drugs included in the study. The accuracy of the method was demonstrated by the analysis of certified authentic hair samples containing common drugs of abuse. The hair-method has broad potential as the measuring range is wide for the target analytes and new drugs can easily be added to the method due to the versatility of the extraction procedure and chromatographic system. PMID:24095804

Montesano, Camilla; Johansen, Sys Stybe; Nielsen, Marie Katrine Klose

2014-01-01

369

A new readout circuit for an ultra high sensitivity CMOS image sensor  

Microsoft Academic Search

We have developed a new readout circuit for highly sensitive CMOS image sensors. The circuit makes it possible to obtain high signal-to-noise ratio (S\\/N) by effectively transferring signal charges accumulated in the photo-diode (PD) to a smaller capacitance. We fabricated and tested a CMOS image sensor with the readout circuit, and confirmed that it has higher sensitivity than conventional passive-type

T. Watabe; M. Goto; H. Ohtake; H. Maruyama; K. Tanioka

2002-01-01

370

Unique TiO 2 paste for high efficiency dye-sensitized solar cells  

Microsoft Academic Search

A novel titanium oxide paste based on Pechini sol–gel method and nanocrystalline titanium oxide powder have been successfully developed. Titanium oxide layers possess high inner surface area assuring high dye loading and well-connected nanocrystalline grains assuring good electron transport within the layer. The dye-sensitized layers have been used to assemble dye-sensitized solar cells with acetonitrile- and ionic liquid-based electrolyte. Overall

U. Opara Krašovec; M. Berginc; M. Ho?evar; M. Topi?

2009-01-01

371

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

372

Highly sensitive potentiometric strip test for detecting high charge density impurities in heparin.  

PubMed

Contamination of heparin with oversulfated chondroitin sulfate (OSCS) became a matter of grave concern in the medical field after many fatal responses to OSCS tainted heparin products occurred during the 2007-2008 period. Even though standard lab-based analytical techniques such as nuclear magnetic resonance (NMR) and strong anion-exchange high performance liquid chromatography (SAX-HPLC) have proven useful for monitoring the OSCS content in heparin products, an easy-to-use, quick, portable, and cost-efficient method is still needed for on-site monitoring during and after the heparin production. In this report, a disposable strip-type electrochemical polyion sensor is described for detection of low levels of OSCS contamination in heparin. A magnetic actuator is incorporated into this simple electrode-based microfluidic device in order to create the mixing effect necessary to achieve equilibrium potential changes of the sensor within a microfluidic channel. The planar membrane electrode detector within the sample channel is prepared with a tridodecylmethylammonium chloride (TDMAC)-doped poly(vinyl chloride) (PVC) membrane essentially equivalent to previously reported polyanion-sensitive electrodes. When the concentration of heparin applied to the single-use strip device is 57 mg/mL (in only 20 ?L of sample), the same concentration recommended in the NMR analysis protocol for detecting OSCS in heparin, the detection limit is 0.005 wt % of OSCS, which is ca. 20 times lower than the reported detection limit of the NMR method. PMID:21500820

Kang, Youngjea; Gwon, Kihak; Shin, Jae Ho; Nam, Hakhyun; Meyerhoff, Mark E; Cha, Geun Sig

2011-05-15

373

Efficient and stable solid-state dye-sensitized solar cells based on a high-molar-extinction-coefficient sensitizer.  

PubMed

The high-molar-extinction-coefficient heteroleptic ruthenium dye, cis-Ru (4,4'-bis(5-octylthieno[3,2-b] thiophen-2-yl)-2,2'-bipyridine) (4,4'-dicarboxyl-2,2'-bipyridine) (NCS)(2), exhibits an AM 1.5 solar (100 mW cm(-2))-to-electric power-conversion efficiency of 4.6% in a solid-state dye-sensitized solar cell (SSDSC) with 2,2', 7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)9,9'-spirobifluorene (spiro-MeOTAD) as the organic hole-transporting material. These SSDSC devices exhibit good durability during accelerated tests under visible-light soaking for 1000 h at 60 degrees C. This demonstration elucidates a class of photovoltaic devices with potential for stable and low-cost power generation. The electron recombination dynamics and charge collection that take place at the dye-sensitized heterojunction are studied by means of impedance and transient photovoltage decay techniques. PMID:19902434

Wang, Mingkui; Moon, Soo-Jin; Xu, Mingfei; Chittibabu, Kethineni; Wang, Peng; Cevey-Ha, Ngoc-Le; Humphry-Baker, Robin; Zakeeruddin, Shaik M; Grätzel, Michael

2010-01-01

374

Is sensitivity to reward associated with the malleability of implicit inclinations toward high-fat food?  

PubMed

Two experiments examined the effect of positive and negative priming on implicit approach and avoidance inclinations toward high-fat food stimuli in participants high or low in reward sensitivity, using personalized unipolar variants of the Implicit Association Test (IAT; A. G. Greenwald, D. E. McGhee, & J. L. K. Schwartz, 1998, "Measuring individual differences in implicit cognition: The Implicit Association Test," Journal of Personality and Social Psychology, Vol. 74, pp. 1464-1480). Participants high in reward sensitivity showed an automatic processing bias that is characterized by a dual vulnerability of being particularly susceptible to priming of the rewarding aspects of high-fat foods, while being unaffected by priming of the negative aspects of those foods. In contrast, participants low in reward sensitivity generally showed no facilitation of implicit-approach inclinations following positive priming, but consistently showed facilitation of implicit-avoidance inclinations following negative priming. These results are consistent with the revised reinforcement sensitivity theory ( J. A. Gray & N. McNaughton, 2000, The neuropsychology of anxiety: An enquiry into the functions of the septo-hippocampal system, 2nd ed., New York, NY, Oxford University Press.) and suggest that the systems mediating reward sensitivity and punishment sensitivity are not orthogonal, as predicted by the separable subsystems hypothesis, but can be interdependent, as predicted by the joint subsystems hypothesis. PMID:23527505

Ashby, Casey R; Stritzke, Werner G K

2013-08-01

375

Fully printed, highly sensitive multifunctional artificial electronic whisker arrays integrated with strain and temperature sensors.  

PubMed

Mammalian-mimicking functional electrical devices have tremendous potential in robotics, wearable and health monitoring systems, and human interfaces. The keys to achieve these devices are (1) highly sensitive sensors, (2) economically fabricated macroscale devices on flexible substrates, and (3) multifunctions beyond mammalian functions. Although highly sensitive artificial electronic devices have been reported, none have been fabricated using cost-effective macroscale printing methods and demonstrate multifunctionalities of artificial electronics. Herein we report fully printed high-sensitivity multifunctional artificial electronic whiskers (e-whisker) integrated with strain and temperature sensors using printable nanocomposite inks. Importantly, changing the composition ratio tunes the sensitivity of strain. Additionally, the printed temperature sensor array can be incorporated with the strain sensor array beyond mammalian whisker functionalities. The sensitivity for the strain sensor is impressively high (?59%/Pa), which is the best sensitivity reported to date (>7× improvement). As the proof-of-concept for a truly printable multifunctional artificial e-whisker array, two- and three-dimensional space and temperature distribution mapping are demonstrated. This fully printable flexible sensor array should be applicable to a wide range of low-cost macroscale electrical applications. PMID:24580035

Harada, Shingo; Honda, Wataru; Arie, Takayuki; Akita, Seiji; Takei, Kuniharu

2014-04-22

376

Longevity Tests of High-Sensitivity BD-PND Bubble Dosimeters  

SciTech Connect

Medium- and very-high-sensitivity neutron bubble dosimeters (BD-PNDs) made by Bubble Technology Industries (BTI) were used to study the life span of such dosimeters in a standard setup with a {sup 252}Cf source. Although data on the longevity of bubble dosimeters with low and medium sensitivity exist, such data for dosimeters with high and very high sensitivity are not readily available. The manufacturer guarantees optimum dosimeter performance for 3 months after receipt. However, it is important to know the change in the dosimeters' characteristics with time, especially after the first 3 months. The long-term performance of four sets of very high sensitivity and one set of medium-sensitivity bubble dosimeters was examined for periods of up to 13 months. During that time, the detectors were exposed and reset more than 20 times. Although departures from initial detection sensitivity were observed in several cases, the detectors indicated a significantly longer life span than stated in the manufacturer's warranty. In addition, the change in the number of bubbles and in evaluated neutron dose as a function of the time from the end of exposure until the dosimeters were read was investigated.

Radev, R; Carlberg, E

2002-07-09

377

Temperature-insensitive miniaturized fiber inline Fabry-Perot interferometer for highly sensitive refractive index measurement.  

PubMed

We report a miniaturized fiber inline Fabry-Perot interferometer (FPI), with an open micro-notch cavity fabricated by one-step fs laser micromachining, for highly sensitive refractive index measurement. The device was tested for measurement of the refractive indices of various liquids including isopropanol, acetone and methanol at room temperature, as well as the temperature-dependent refractive index of deionized water from 3 to 90 degrees C. The sensitivity for measurement of refractive index change of water was 1163 nm/RIU at the wavelength of 1550 nm. The temperature cross-sensitivity of the device was about 1.1x10(-6) RIU/degrees C. The small size, all-fiber structure, small temperature dependence, linear response and high sensitivity, make the device attractive for chemical and biological sensing. PMID:18542685

Wei, Tao; Han, Yukun; Li, Yanjun; Tsai, Hai-Lung; Xiao, Hai

2008-04-14

378

A highly sensitive humidity sensor based on a nanofibrous membrane coated quartz crystal microbalance  

NASA Astrophysics Data System (ADS)

A novel humidity sensor was fabricated by electrospinning deposition of nanofibrous polyelectrolyte membranes as sensitive coatings on a quartz crystal microbalance (QCM). The results of sensing experiments indicated that the response of the sensors increased by more than two orders of magnitude with increasing relative humidity (RH) from 6 to 95% at room temperature, exhibiting high sensitivity, and that, in the range of 20-95% RH, the Log(?f) showed good linearity. The sensitivity of fibrous composite polyacrylic acid (PAA)/poly(vinyl alcohol) (PVA) membranes was two times higher than that of the corresponding flat films at 95% RH. Compared with fibrous PAA/PVA membranes, the nanofibrous PAA membranes exhibited remarkably enhanced humidity sensitivity due to their high PAA content and large specific surface area caused by the formation of ultrathin nanowebs among electrospun fibers. Additionally, the resultant sensors exhibited a good reversible behavior and good long term stability.

Wang, Xianfeng; Ding, Bin; Yu, Jianyong; Wang, Moran; Pan, Fukui

2010-02-01

379

Design of a highly sensitive surface plasmon resonance sensor using aluminum-based diffraction grating  

NASA Astrophysics Data System (ADS)

A highly-sensitive grating-based surface plasmon resonance (SPR) sensor is proposed. The angular interrogation method has been used to study the performance of the sensor, and high sensitivity is obtained if the -1st diffraction order is used to excite surface plasmon (SP). The sensitivity as well as the width of the SPR curves and reflective amplitude is considered for designing the sensor. Compared with the conventional gold (Au)-based or silver (Ag)-based SPR sensor, it is found that the aluminum (Al)-based sensor has the best performance. The oxidation problem of an Al-based SPR sensor has been addressed by coating it with an ultrathin gold film on the surface. Numerical simulations based on rigorous coupled wave analysis (RCWA) show that the sensitivity of the optimized sensor is 245°/RIU (degree per refractive index unit).

Su, Wei; Zheng, Gaige; Li, Xiangyin

2012-10-01

380

Green laser excited surface plasmon resonance biosensor utilizing highly sensitive phase interrogation detection  

NASA Astrophysics Data System (ADS)

Surface plasmon resonance (SPR) biosensors have been widely used for dynamical analysis of molecular affinity, bacterium screening, and drug discovery due to its advantages of label-free detection, dynamic interaction analysis, small sample volume, and ultra sensitivity (feasibility of single molecular detection). Recently, SPR biosensing for cell imaging known as SPR microscopy (SPRM) has attracted great attention due to the characteristics of SPR biosensors. However, it is well known that the trends of sensitivity and spatial resolution are opposite to each other: Surface plasmon waves (SPWs) with shorter wavelength which provides higher spatial resolution has less sensitivity. It is known that the spatial resolution of SPRM is limited by the propagation length of surface plasmon wave (SPW) along the metaldielectric interface. SPW excited by 632.8 nm light has the propagation length of 3 um. This length becomes longer when a longer wavelength is selected. While most of SPR biosensors are built with 632.8 nm or longer wavelength for high sensitivity, using 532nm light to excite SPWs is desired for submicron resolution since the propagation length is around 150 nm. Different from current phase interrogation methods, the proposed phase interrogation method is highly sensitive and suitable for CCD imaging. Although it is generally believed that SPWs with wavelength 532nm has poor sensitivity, the experimental result showed that the setup can reach the sensitivity lower than 2×10-6 RIU when sucrose is used as the test sample.

Chen, How-Foo; Hsu, Wei-Chen; Wang, Ya-Jung; Yen, Ta-Jen

2010-04-01

381

High sensitivity molecular detection with enzyme-linked immuno-sorbent assay (ELISA)-type immunosensing  

NASA Astrophysics Data System (ADS)

Here we describe an immunosensing method, which is designed for high sensitivity sensing of various substances utilizing specificity of antigen-antibody (ELISA-type) interaction. The building up of the nanostructured sensing interface and the immunointeraction at the surface were characterized by atomic force microscopy. The proposed design makes potentially feasible attaining ultimate single-molecule sensitivity upon optimization of the system. The first non-optimized prototype described here has already demonstrated sensitivity to the presence of dinitrophenyl (DNP) in concentrations as low as 10 pM, which is 100 times better than reported limits of detection of DNP with a traditional enzyme-linked immuno-sorbent assay setup.

Pita, Marcos; Cui, Lili; Gaikwad, Ravi M.; Katz, Evgeny; Sokolov, Igor

2008-09-01

382

Highly Sensitive Infrared Detector Fabricated with Thin Film of High Tc Y-Ba-Cu-O Superconductor. Phase 1.  

National Technical Information Service (NTIS)

In the phase I study of the project entitled 'Highly Sensitive Infrared Detector Fabricated with Thin Film of High Tc Y-Ba-Cu-O Superconductor using Pulsed Laser', we have successfully deposited thin films of Y-Ba-Cu-O on MgO/TcO2 substrate by plasma assi...

R. Rao

1989-01-01

383

High Sensitive Formaldehyde Gas Sensor Prepared by R.F. Induction Plasma Deposition Method  

NASA Astrophysics Data System (ADS)

The present work is concerned on developing high sensitive and high performance SnO2-based gas sensors for detecting indoor air pollutant formaldehyde gas. The film was deposited on an alumina substrate using R.F. Induction Plasma Deposition technique. Physical properties of sensing films were examined by SEM, XRD method. The sensors showed high sensitivity to typical HCHO gas at an extremely low gas concentration of 20 parts-per-billion (ppb) with quick response and recovery time at several minutes. The effect of the doping of various metallic additives on the gas-sensing properties and operating temperature dependency were also investigated in the work.

Shi, Liqin; Gao, Wei; Hasegawa, Yuki; Katsube, Teruaki; Nakano, Mamoru; Nakamura, Kiyozumi

384

Influence of dispersion on sensitivity of highly birefringent fibers to temperature and hydrostatic pressure.  

PubMed

The influence of dispersion on the sensitivity of highly birefringent fibers to temperature and hydrostatic pressure was experimentally investigated. In fibers with geometric birefringence that shows high dispersion, great differences were observed between group and phase sensitivities to temperature and hydrostatic pressure. This difference may reach 400% in the case of temperature response. In contrast, in weakly dispersive fibers with stress-induced birefringence these differences were of the order of 8% and 14%, respectively, for temperature and pressure. The influence of the dispersion effect on the temperature compensation of white-light interferometric sensors based on highly birefringent fibers was also discussed. PMID:18273266

Urbanczyk, W; Bock, W J

1998-05-20

385

High-sensitivity Fabry-Perot interferometric pressure sensor based on a nanothick silver diaphragm.  

PubMed

We present a fiber-optic extrinsic Fabry-Perot interferometer pressure sensor based on a nanothick silver diaphragm. The sensing diaphragm, with a thickness measured in a few hundreds of nanometers, is fabricated by the electroless plating method, which provides a simple fabrication process involving a high-quality diaphragm at a low cost. The sensor exhibits a relatively linear response within the pressure variation range of 0-50 kPa, with a high pressure sensitivity of 70.5 nm/kPa. This sensor is expected to have potential applications in the field of highly sensitive pressure sensors. PMID:22854444

Xu, Feng; Ren, Dongxu; Shi, Xiaolong; Li, Can; Lu, Weiwei; Lu, Lu; Lu, Liang; Yu, Benli

2012-01-15

386

A highly sensitive, integrable, multimode, interferometric, evanescent-wave chem\\/bio sensor  

Microsoft Academic Search

A fully integrated optical chem\\/bio sensor complete with integrated source, chemically sensitive waveguide, detector arrays, and associated signal processing electronics on a Si-CMOS chip is a challenging, but highly desirable goal. An evanescent-wave multimode interferometric sensing element is a sensitive method for sensing, which is easily integrated on Si-CMOS. This work is concerned with the design, analysis, and demonstration of

Jeffrey J. Lillie

2005-01-01

387

Fabrication of a Highly Sensitive Chemical Sensor Based on ZnO Nanorod Arrays  

PubMed Central

We report a novel method for fabricating a highly sensitive chemical sensor based on a ZnO nanorod array that is epitaxially grown on a Pt-coated Si substrate, with a top–top electrode configuration. To practically test the device, its O2 and NO2 sensing properties were investigated. The gas sensing properties of this type of device suggest that the approach is promising for the fabrication of sensitive and reliable nanorod chemical sensors.

2010-01-01

388

A preliminary application of highly sensitive nitrate ISFETs to acid-rain monitoring  

Microsoft Academic Search

Highly sensitive nitrate ion-sensitive field-effect transistors (nitrate ISFETs) have been investigated for acid-rain monitoring by using specially designed hydrophobic nitrate-sensing materials. Using this nitrate-sensing membrane, we have prepared a prototype nitrate checker composed of a nitrate ISFET and a silver\\/silver chloride reference electrode and have demonstrated its preliminary application to real samples of rain water. The correlation coefficient between the

S. Wakida; T. Oizaki; M. Yamane; K. Higashi

1995-01-01

389

Measurements of thermophysical properties of nickel with a new highly sensitive pyrometer  

Microsoft Academic Search

A new, sensitive, and fast (response time, 100 ns) pyrometer used for the measurement of temperature in pulse heating experiments is described. The monochromatic instrument may use two detectors, namely, a Si diode and an InGaAs diode. Since monochromatic pyrometers usually are “self-calibrated” with the plateau of the melting transition of the investigated metal, a high sensitivity is desirable. The

W. Obendrauf; E. Kaschnitz; G. Pottlacher; H. Jäger

1993-01-01

390

A high sensitivity temperature sensor realized with cascaded long period fiber grating-based Sagnac loop  

NASA Astrophysics Data System (ADS)

A novel cascaded structure which comprises long period fiber gratings inscribed in a single mode fiber and a Panda polarization maintaining fiber is proposed. A high sensitivity temperature sensor is obtained when the novel cascaded structure is inserted into Sagnac loop. Its response to temperature and polarization is investigated. The temperature sensitivity reaches up to -1.26 nm/ °C. Furthermore, the experimental results show that notch 1 is almost immune to the state of polarization.

Ruan, Juan; Qin, Zi Xiong; Zeng, Qin Ke

2014-05-01

391

Novel polyaniline\\/PVDF\\/BaTiO 3 hybrid composites with high piezo-sensitivity  

Microsoft Academic Search

Polyvinylidene fluoride (PVDF)–barium titanate (BaTiO3)–polyaniline (PANI) hybrid composites were prepared by conventional powder processing technique which exhibited remarkably high piezo-sensitivity. The effect of poling of these semi-insulating composites on their piezo-response was quite dramatic. Sensitivity factors of 3000 could be achieved for even small poling voltages as low as 180V\\/mm. The synergistic effect was obtained only when all three components,

R. Patil; A. Ashwin; S. Radhakrishnan

2007-01-01

392

Fabrication of a Highly Sensitive Chemical Sensor Based on ZnO Nanorod Arrays  

NASA Astrophysics Data System (ADS)

We report a novel method for fabricating a highly sensitive chemical sensor based on a ZnO nanorod array that is epitaxially grown on a Pt-coated Si substrate, with a top-top electrode configuration. To practically test the device, its O2 and NO2 sensing properties were investigated. The gas sensing properties of this type of device suggest that the approach is promising for the fabrication of sensitive and reliable nanorod chemical sensors.

Park, Jae Young; Choi, Sun-Woo; Kim, Sang Sub

2010-02-01

393

High-sensitivity temperature-independent differential pressure sensor using fiber Bragg gratings.  

PubMed

By means of novel packaged-structure design, a temperature independent differential pressure sensor based on fiber Bragg gratings with high sensitivity is experimentally demonstrated. The differential pressure sensitivity of the sensor can reach to 821.87nm/MPa. This device can also be used for simultaneous measurement of temperature and differential pressure, which is suitable for applications involving measurement of liquid level, liquid density or specific gravity detection. PMID:18825240

Sheng, Hao-Jan; Liu, Wen-Fung; Lin, Kuei-Ru; Bor, Sheau-Shong; Fu, Ming-Yue

2008-09-29

394

PVDF film micro fabrication for the robotics skin sensor having flexibility and high sensitivity  

Microsoft Academic Search

This paper provide a novel and potential method to realize a flexible and high sensitive, high resolution skin sensor useful for the application of robotic skin. MEMS technology was applied and by etching process 140?300\\/40- µm of micro structures were realized easily directly on the elongated and polarized polyvinylidene fluoride (? - PVDF) film that will be used as the

Hiro Han; Yuusaku Nakagawa; Yasuyuki Takai; Kunitomo Kikuchi; Shigeki Tsuchitani

2011-01-01

395

The contribution of the sensitive high-resolution ion microprobe (SHRIMP) to lunar geochronology  

Microsoft Academic Search

The sensitive high-resolution ion microprobe (SHRIMP) developed at the Australian National University (ANU) was the first of the high-resolution ion microprobes. The impact of this instrument on geochronological research over the last twenty years has been immense. This is particularly so for lunar geochronology where it has opened up avenues of research that were not possible using conventional TIMS techniques.

R. T. Pidgeon; A. A. Nemchin; C. Meyer

2010-01-01

396

A four-pixel matched collimator for high-sensitivity SPECT imaging  

NASA Astrophysics Data System (ADS)

We propose a wide aperture parallel-hole collimator that we call a 4-pixel matched collimator (4-PMC) for high-sensitivity SPECT imaging. The hole size of the 4-PMC is matched to four detector pixels; that is, there are four (2 × 2) pixels per collimator hole. By contrast, a 1-pixel matched collimator (1-PMC) is defined as a collimator whose hole size is matched to one detector pixel. We evaluated four types of collimator (high-resolution collimator versions and high-sensitivity collimator versions of both 4-PMC and 1-PMC) by simulation. SPECT images of a cylindrical phantom with cold spots in the noise-free condition demonstrated that the 4-PMC provided a higher-contrast image than the 1-PMC for the same collimator version. In addition, SPECT images at the noise level corresponding to a human cerebral blood flow study suggested that the high-sensitivity version of the 4-PMC provided the highest contrast image among the four collimator types. In conclusion, the high-sensitivity SPECT system using the 4-PMC can improve the trade-off between spatial resolution and sensitivity and will consequently provide improved image contrast for clinical studies of the human brain compared with the SPECT system using the 1-PMC.

Suzuki, Atsuro; Takeuchi, Wataru; Ishitsu, Takafumi; Tsuchiya, Katsutoshi; Ueno, Yuichiro; Kobashi, Keiji

2013-04-01

397

Image quality and dose efficiency of high energy phase sensitive x-ray imaging: Phantom studies  

PubMed Central

The goal of this preliminary study was to perform an image quality comparison of high energy phase sensitive imaging with low energy conventional imaging at similar radiation doses. The comparison was performed with the following phantoms: American College of Radiology (ACR), contrast-detail (CD), acrylic edge and tissue-equivalent. Visual comparison of the phantom images indicated comparable or improved image quality for all phantoms. Quantitative comparisons were performed through ACR and CD observer studies, both of which indicated higher image quality in the high energy phase sensitive images. The results of this study demonstrate the ability of high energy phase sensitive imaging to overcome existing challenges with the clinical implementation of phase contrast imaging and improve the image quality for a similar radiation dose as compared to conventional imaging near typical mammography energies. In addition, the results illustrate the capability of phase sensitive imaging to sustain the image quality improvement at high x-ray energies and for – breast – simulating phantoms, both of which indicate the potential to benefit fields such as mammography. Future studies will continue to investigate the potential for dose reduction and image quality improvement provided by high energy phase sensitive contrast imaging.

Wong, Molly Donovan; Wu, Xizeng; Liu, Hong

2014-01-01

398

High degree gravitational sensitivity from Mars orbiters for the GMM-1 gravity model  

NASA Technical Reports Server (NTRS)

Orbital sensitivity of the gravity field for high degree terms (greater than 30) is analyzed on satellites employed in a Goddard Mars Model GMM-1, complete in spherical harmonics through degree and order 50. The model is obtained from S-band Doppler data on Mariner 9 (M9), Viking Orbiter 1 (VO1), and Viking Orbiter 2 (VO2) spacecraft, which were tracked by the NASA Deep Space Network on seven different highly eccentric orbits. The main sensitivity of the high degree terms is obtained from the VO1 and VO2 low orbits (300 km periapsis altitude), where significant spectral sensitivity is seen for all degrees out through degree 50. The velocity perturbations show a dominant effect at periapsis and significant effects out beyond the semi-latus rectum covering over 180 degrees of the orbital groundtrack for the low altitude orbits. Because of the wideband of periapsis motion covering nearly 180 degrees in w and +39 degrees in latitude coverage, the VO1 300 km periapsis altitude orbit with inclination of 39 degrees gave the dominant sensitivity in the GMM-1 solution for the high degree terms. Although the VO2 low periapsis orbit has a smaller band of periapsis mapping coverage, it strongly complements the VO1 orbit sensitivity for the GMM-1 solution with Doppler tracking coverage over a different inclination of 80 degrees.

Lerch, F. J.; Smith, D. E.; Chan, J. C.; Patel, G. B.; Chinn, D. S.

1994-01-01

399

Periodically porous top electrodes on vertical nanowire arrays for highly sensitive gas detection.  

PubMed

Nanowires of various materials and configurations have been shown to be highly effective in the detection of chemical and biological species. In this paper, we report a novel, nanosphere-enabled approach to fabricating highly sensitive gas sensors based on ordered arrays of vertically aligned silicon nanowires topped with a periodically porous top electrode. The vertical array configuration helps to greatly increase the sensitivity of the sensor while the pores in the top electrode layer significantly improve sensing response times by allowing analyte gases to pass through freely. Herein, we show highly sensitive detection to both nitrogen dioxide (NO(2)) and ammonia (NH(3)) in humidified air. NO(2) detection down to 10 parts per billion (ppb) is demonstrated and an order-of-magnitude improvement in sensor response time is shown in the detection of NH(3). PMID:21817785

In, Hyun Jin; Field, Christopher R; Pehrsson, Pehr E

2011-09-01

400

Periodically porous top electrodes on vertical nanowire arrays for highly sensitive gas detection  

NASA Astrophysics Data System (ADS)

Nanowires of various materials and configurations have been shown to be highly effective in the detection of chemical and biological species. In this paper, we report a novel, nanosphere-enabled approach to fabricating highly sensitive gas sensors based on ordered arrays of vertically aligned silicon nanowires topped with a periodically porous top electrode. The vertical array configuration helps to greatly increase the sensitivity of the sensor while the pores in the top electrode layer significantly improve sensing response times by allowing analyte gases to pass through freely. Herein, we show highly sensitive detection to both nitrogen dioxide (NO2) and ammonia (NH3) in humidified air. NO2 detection down to 10 parts per billion (ppb) is demonstrated and an order-of-magnitude improvement in sensor response time is shown in the detection of NH3.

In, Hyun Jin; Field, Christopher R.; Pehrsson, Pehr E.

2011-09-01

401

RAD51C-deficient cancer cells are highly sensitive to the PARP inhibitor olaparib.  

PubMed

A PARP inhibitor is a rationally designed targeted therapy for cancers with impaired DNA repair abilities. RAD51C is a paralog of RAD51 that has an important role in the DNA damage response. We found that cell lines sensitive to a novel oral PARP inhibitor, olaparib, had low levels of RAD51C expression using microarray analysis, and we therefore hypothesized that low expression of RAD51C may hamper the DNA repair process, resulting in increased sensitivity to olaparib. Compared with the cells with normal RAD51C expression levels, RAD51C-deficient cancer cells were more sensitive to olaparib, and a higher proportion underwent cell death by inducing G2-M cell-cycle arrest and apoptosis. The restoration of RAD51C in a sensitive cell line caused attenuation of olaparib sensitivity. In contrast, silencing of RAD51C in a resistant cell line enhanced the sensitivity to olaparib, and the number of RAD51 foci decreased with ablated RAD51C expression. We also found the expression of RAD51C was downregulated in cancer cells due to epigenetic changes and RAD51C expression was low in some gastric cancer tissues. Furthermore, olaparib significantly suppressed RAD51C-deficient tumor growth in a xenograft model. In summary, RAD51C-deficient cancer cells are highly sensitive to olaparib and offer preclinical proof-of-principle that RAD51C deficiency may be considered a biomarker for predicting the antitumor effects of olaparib. PMID:23512992

Min, Ahrum; Im, Seock-Ah; Yoon, Young-Kwang; Song, Sang-Hyun; Nam, Hyun-Jin; Hur, Hyung-Seok; Kim, Hwang-Phill; Lee, Kyung-Hun; Han, Sae-Won; Oh, Do-Youn; Kim, Tae-You; O'Connor, Mark J; Kim, Woo-Ho; Bang, Yung-Jue

2013-06-01

402

High Temperature and High Sensitive NOx Gas Sensor with HeteroJunction Structure using Laser Ablation Method  

Microsoft Academic Search

In order to develop a high temperature (200°C˜400°C) and high sensitive NOx gas sensor, we developed a new structure of SiC-based hetero-junction device Pt\\/SnO2\\/SiC\\/Ni, Pt\\/In2O3\\/SiC\\/Ni and Pt\\/WO3\\/SiC\\/Ni using a laser ablation method for the preparation of both metal (Pt) electrode and metal-oxide film. It was found that Pt\\/In2O3\\/SiC\\/Ni sensor shows higher sensitivity to NO2 gas compared with the Pt\\/SnO2\\/SiC\\/Ni and

Wei Gao; Liqin Shi; Yuki Hasegawa; Teruaki Katsube

2006-01-01

403

High temperature and high sensitive NOx gas sensor with hetero-junction structure using laser ablation method  

Microsoft Academic Search

In order to develop a high temperature (200°C ? 400°C) and high sensitive NOx gas sensor, we developed a new structure of SiC-based hetero-junction device Pt\\/SnO2\\/SiC\\/Ni and Pt\\/WO3\\/SiC\\/Ni using a laser ablation method for the preparation of both metal (Pt) electrode and metal-oxide film. It was found that Pt\\/SnO2\\/SiC\\/Ni sensor show higher sensitivity to NO2 gas compared with the Pt\\/WO3\\/SiC\\/Ni

Wei Gaol; Liqin Shi; S. A. Khan; Y. Hasegawa; T. Katsube

2005-01-01

404

Ultra high vacuum pumping system and high sensitivity helium leak detector  

DOEpatents

An improved helium leak detection method and apparatus are disclosed which increase the leak detection sensitivity to 10{sup {minus}13} atm cc/s. The leak detection sensitivity is improved over conventional leak detectors by completely eliminating the use of o-rings, equipping the system with oil-free pumping systems, and by introducing measured flows of nitrogen at the entrances of both the turbo pump and backing pump to keep the system free of helium background. The addition of dry nitrogen flows to the system reduces back streaming of atmospheric helium through the pumping system as a result of the limited compression ratios of the pumps for helium. 2 figs.

Myneni, G.R.

1997-12-30

405

Alkanethiol-functionalized terahertz metamaterial as label-free, highly-sensitive and specific biosensor.  

PubMed

Specific biorecognition is essential for many biological processes, for which highly sensitive and label-free biosensors are strongly demanded. The recently developed metamaterials are a potential choice for biosensing due to their exotic properties. In the current work, a label-free and specific sensor for streptavidin-agarose (SA) was fabricated based on terahertz metamaterial functionlized by octadecanthiols and biotins. Both low and high frequency resonant modes from the metamaterials are found applicable for the detection of SA, and a redshift up to 6.76 GHz for the high frequency mode was measured in the undiluted commercial solution. The low frequency mode is attributed to inductor-capacitor (LC) oscillation, while the high frequency mode originates from the plasmonic dipole oscillator, both of which are highly sensitive to the micro-environment change. Adsorption of SA of different concentrations causes different redshifts, and the replacement of high refractive-index substrate with low refractive-index substrate can efficiently promote the sensitivity, well agreeing with the numerical simulation. Moreover, for a particular biomolecule, the sensitivity can be further improved by optimizing the metamaterial design. This method might be very helpful for desirable biorecognition in biology, medicine, and drug industry. PMID:23261700

Wu, Xiaojun; Quan, Baogang; Pan, Xuecong; Xu, Xinlong; Lu, Xinchao; Gu, Changzhi; Wang, Li

2013-04-15

406

Polarimetric and intermodal interference sensitivity to hydrostatic pressure, temperature, and strain of highly birefringent optical fibers.  

PubMed

The sensitivity to hydrostatic pressure, temperature, and strain of elliptical-core, D-shaped, bow-tie highly birefringent fibers is experimentally investigated. Both polarimetric and polarization sensitive LP(01)-LP(11) intermodal interferometric responses are studied. The sensitivities are expressed in terms of the experimental parameters T(x,j) describing a 2pi phase shift in the cosine response. It is found that bow-tie fibers exhibit a linear response to all the studied external perturbations except for the polarimetric response of the fundamental mode to temperature, while elliptical-core and D-shaped fibers are characterized by a nonlinear sensitivity to both temperature and hydrostatic pressure. The application to fiber-optic sensors of each type of fiber is discussed. PMID:19829467

Bock, W J; Eftimov, T A

1993-11-15

407

High-Sensitivity X-ray Polarimetry with Amorphous Silicon Active-Matrix Pixel Proportional Counters  

NASA Technical Reports Server (NTRS)

Photoelectric X-ray polarimeters based on pixel micropattern gas detectors (MPGDs) offer order-of-magnitude improvement in sensitivity over more traditional techniques based on X-ray scattering. This new technique places some of the most interesting astronomical observations within reach of even a small, dedicated mission. The most sensitive instrument would be a photoelectric polarimeter at the focus of 2 a very large mirror, such as the planned XEUS. Our efforts are focused on a smaller pathfinder mission, which would achieve its greatest sensitivity with large-area, low-background, collimated polarimeters. We have recently demonstrated a MPGD polarimeter using amorphous silicon thin-film transistor (TFT) readout suitable for the focal plane of an X-ray telescope. All the technologies used in the demonstration polarimeter are scalable to the areas required for a high-sensitivity collimated polarimeter. Leywords: X-ray polarimetry, particle tracking, proportional counter, GEM, pixel readout

Black, J. K.; Deines-Jones, P.; Jahoda, K.; Ready, S. E.; Street, R. A.

2003-01-01

408

High open circuit voltages of solar cells based on quantum dot and dye hybrid-sensitization  

NASA Astrophysics Data System (ADS)

A type of solar cell based on quantum dot (QD) and dye hybrid-sensitized mesoporous TiO2 film electrode was designed and reported. The electrode was consisted of a TiO2 nanoparticle (NP) thin film layer sensitized with CdS quantum dot (QD) and an amorphous TiO2 coated TiO2 NP thin film layer that sensitized with C106 dye. The amorphous TiO2 layer was obtained by TiCl4 post-treatment to improve the properties of solar cells. Research showed that the solar cells fabricated with as-prepared hybrid-sensitized electrode exhibited excellent photovoltaic performances and a fairly high open circuit voltage of 796 mV was achieved.

Zhao, Yujie; Bala, Hari; Zhao, Wanyu; Chen, Jingkuo; Li, Huayang; Fu, Wuyou; Sun, Guang; Cao, Jianliang; Zhang, Zhanying

2014-01-01

409

A versatile high-speed bipolar charge-sensitive preamplifier for calorimeter applications  

Microsoft Academic Search

A high-speed charge-sensitive preamplifier (CSP) to be used in silicon calorimeters has been realized. The main features of this circuit are: high slew rate (larger than 500 V\\/?s), low noise, large output swing (5 V), high dynamic range (of the order of 90 dB), and 50-? output drive capability. In addition, the CSP is designed to allow adaptation of its

A. Baschirotto; R. Castello; G. Pessina; P. G. Rancoita; A. Seidman

1998-01-01

410

Realization of a versatile high-speed bipolar charge sensitive preamplifier for calorimeter applications  

Microsoft Academic Search

A versatile high-speed Charge Sensitive Preamplifier (CSP) to be used in silicon calorimeters is presented. The main features of this circuit are low noise, high slew-rate (larger than 500V\\/¿s), high dynamic range (of the order of 90dB), and 100¿ output drive capability. The bias current of the CSP can be adjusted, in order to optimise the trade-off between power and

A. Baschirotto; R. Castello; A. Gola; G. Pessina; P. G. Rancoita; M. Redaelli; A. Seidman; M. Volpi

1995-01-01

411

High-performance dye-sensitized solar cell with a multiple dye system  

NASA Astrophysics Data System (ADS)

A dye-sensitized solar cell (DSC) using two dyes achieved high external quantum efficiency as sensitizers. We confirmed that terpyridine complex (black dye, Solaronix) and an indoline dye (D131, Mitsubishi Paper Mill) were adsorbed by the TiO2 electrode without either dye interfering with the electron transfer of the other dye to the electrode. The high performance of the new arrangement is made possible by the dissociation function of these two particular dyes. The multiple dye system achieved a power conversion efficiency of 11.0%. Moreover, the fabrication of the multiple dye system only mixed the two reagents in one pot.

Ogura, Reiko Yoneya; Nakane, Shigeru; Morooka, Masahiro; Orihashi, Masaki; Suzuki, Yusuke; Noda, Kazuhiro

2009-02-01

412

High sensitivity pressure sensor based on a birefringent microfiber loop mirror  

NASA Astrophysics Data System (ADS)

Highly birefringent (Hi-Bi) microfiber-based fiber loop mirrors (FLMs) are studied for gas pressure measurement. A elliptical microfiber is made by tapering a femtosecond laser-processed single mode fiber and demonstrated a very high birefringence of up to 10-2 . The microfiber is housed within a pressure tube with which gas pressure measurement is carried out. The robust microfiber sensor demonstrates a pressure sensitivity of 6 pm/kPa with a temperature cross-sensitivity of less than 0.01 nm/K.

Jin, Wa; Xuan, Hai-Feng; Wang, Chao; Jin, Wei

2013-09-01

413

A hybrid LPG/CFBG for highly sensitive refractive index measurements.  

PubMed

A simple and high sensitive method employing a hybrid long period grating (LPG)/chirped fiber Bragg grating (CFBG) for refractive index (RI) measurements is proposed and investigated experimentally. The wide wavelength range of backward cladding modes are excited through the coupling and recoupling between LPG and CFBG. Experimental results indicate that the recoupled cladding modes between LPG and CFBG and core mode are modulated by the surrounding RI and highly sensitive RI measurements can be achieved by simply measuring the reflected intensity changes of the recoupled cladding modes and core mode. PMID:22969347

Sun, An; Wu, Zhishen

2012-01-01

414

A Hybrid LPG/CFBG for Highly Sensitive Refractive Index Measurements  

PubMed Central

A simple and high sensitive method employing a hybrid long period grating (LPG)/chirped fiber Bragg grating (CFBG) for refractive index (RI) measurements is proposed and investigated experimentally. The wide wavelength range of backward cladding modes are excited through the coupling and recoupling between LPG and CFBG. Experimental results indicate that the recoupled cladding modes between LPG and CFBG and core mode are modulated by the surrounding RI and highly sensitive RI measurements can be achieved by simply measuring the reflected intensity changes of the recoupled cladding modes and core mode.

Sun, An; Wu, Zhishen

2012-01-01

415

High potential sensitivity in heterodyne amplitude-modulation Kelvin probe force microscopy  

NASA Astrophysics Data System (ADS)

A surface potential measurement method using amplitude-modulation and heterodyne techniques is proposed. The effect of the stray capacitance between a cantilever and a sample in Kelvin probe force microscopy and the electrostatic force spectroscopy measurements are almost completely removed, because the distance (z) dependence of the modulated electrostatic force increases from 1/z to1/z2. This method improves the sensitivity of short range forces and reduces the surface potential measurement crosstalk that is induced by topographic feedback. This method has the advantage of high potential sensitivity due to the high cantilever Q value under vacuum. Quantitative surface potential measurements are demonstrated.

Sugawara, Yasuhiro; Kou, Lili; Ma, Zongmin; Kamijo, Takeshi; Naitoh, Yoshitaka; Jun Li, Yan

2012-05-01

416

Combined taper-and-cylinder optical fiber probes for highly sensitive surface-enhanced Raman scattering  

NASA Astrophysics Data System (ADS)

A combined taper-and-cylinder optical fiber fabricated by simple tube-etching and modified with silver nanoparticles is developed for surface-enhanced Raman scattering (SERS) sensing. It has the advantages of high light transmission efficiency and large interaction areas for light and silver nanoparticles. The detection of rhodamine 6G in remote mode indicates that the sensitivity could realize 10-13 M. The fiber SERS probe with high flexibility and sensitivity shows great potential for molecule detection in various sensing applications.

Liu, Ting; Zhou, Lei; Zhang, Zhonghuan; Xiao, Xiaosheng; Zhou, Minjuan; Yang, Changxi

2014-02-01

417

High-resolution, high sensitivity detectors for molecular imaging with radionuclides: The coded aperture option  

NASA Astrophysics Data System (ADS)

Molecular imaging with radionuclides is a very sensitive technique because it allows to obtain images with nanomolar or picomolar concentrations. This has generated a rapid growth of interest in radionuclide imaging of small animals. Indeed radiolabeling of small molecules, antibodies, peptides and probes for gene expression enables molecular imaging in vivo, but only if a suitable imaging system is used. Detecting small tumors in humans is another important application of such techniques. In single gamma imaging, there is always a well known tradeoff between spatial resolution and sensitivity due to unavoidable collimation requirements. Limitation of the sensitivity due to collimation is well known and affects the performance of imaging systems, especially if only radiopharmaceuticals with limited uptake are available. In many cases coded aperture collimation can provide a solution, if the near field artifact effect can be eliminated or limited. At least this is the case for "small volumes" imaging, involving small animals. In this paper 3D-laminography simulations and preliminary measurements with coded aperture collimation are presented. Different masks have been designed for different applications showing the advantages of the technique in terms of sensitivity and spatial resolution. The limitations of the technique are also discussed.

Cusanno, F.; Cisbani, E.; Colilli, S.; Fratoni, R.; Garibaldi, F.; Giuliani, F.; Gricia, M.; Lo Meo, S.; Lucentini, M.; Magliozzi, M. L.; Santavenere, F.; Lanza, R. C.; Majewski, S.; Cinti, M. N.; Pani, R.; Pellegrini, R.; Orsini Cancelli, V.; De Notaristefani, F.; Bollini, D.; Navarria, F.; Moschini, G.

2006-12-01

418