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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

2013-08-26

2

Development of a highly sensitive and selective UPLC/MS/MS method for the simultaneous determination of testosterone and 5alpha-dihydrotestosterone in human serum to support testosterone replacement therapy for hypogonadism.  

PubMed

A highly sensitive and selective quantitative method to accurately determine testosterone (Te) and 5alpha-dihydrotestosterone (DHT) in human serum is crucial to the success of Te replacement therapy for hypogonadism. To this end we have developed and validated a semi-automated and relatively high-throughput method in a 96-well plate format using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC/MS/MS) for the simultaneous determination of Te and DHT in human serum. Te and DHT along with the internal standards [(2)H(3)]-Te and [(2)H(3)]-DHT were extracted from 300 microL of human serum by liquid-liquid extraction using methyl tertiary-butyl ether (MTBE), followed by derivatization with 2,3-pyridinedicarboxylic anhydride and solid-phase extraction for sample clean up. A novel chemical derivatization approach using 2,3-pyridinedicarboxylic anhydride was employed to achieve the MS sensitivity and selectivity required for DHT. Baseline separation of Te and DHT derivatives from endogenous steroid derivatives was achieved using UPLC technology on a C18 stationary-phase column with 1.7 microm particle size. The validity of using double charcoal-stripped female human serum as surrogate matrix for preparation of calibration standards was demonstrated through standard addition experiments. The method was validated over the concentration ranges of 0.2-40 ng/mL for Te and 0.01-2 ng/mL for DHT. The validation and study sample analysis results show that the method is rugged, precise, accurate, and well suited to support pharmacokinetic studies where approximately 300 samples can be extracted and analyzed in 1 day. PMID:18329061

Licea-Perez, Hermes; Wang, Sherry; Szapacs, Matthew E; Yang, Eric

2008-02-02

3

A fast, sensitive, and high throughput method for the determination of cefuroxime lysine in dog plasma by UPLC-MS/MS.  

PubMed

In order to investigate the preclinical pharmacokinetics of cefuroxime lysine, a fast, sensitive and high throughput UPLC-ESI-MS/MS method has been developed and validated for the quantitative determination of cefuroxime in dog plasma. Cefuroxime and IS phenacetin were extracted from plasma samples by PPT or LLE procedure, and then separated on an ACQUITY UPLC™ BEH C(18) column with an isocratic elution of acetonitrile-0.1% formic acid in 10mM ammonium acetate (40:60, v/v). MRM using the fragmentation transitions of m/z 442 ? 364 and 180 ? 110 in positive ESI mode was performed to quantify cefuroxime and IS, respectively. The calibration curves were linear over the concentration range of 2-400 ?g/ml for PPT and 0.01-5 ?g/ml for LLE. The LLOQ was 0.01 ?g/ml. The intra- and inter-day precisions in all samples were no more than 8.1%, while the accuracy was within ± 6.2% of nominal values. The method was successfully applied to the evaluation of pharmacokinetic parameters of cefuroxime lysine in beagle dogs. PMID:22284463

Zhao, Longshan; Zhao, Yunli; Li, Qing; Chen, Xiaohui; Xiao, Feng; He, Bosai; Wang, Jie; Bi, Kaishun

2011-11-26

4

Biopharmaceutical and pharmacokinetic characterization of matrine as determined by a sensitive and robust UPLC-MS/MS method  

PubMed Central

The purpose of this research was to develop a sensitive and reproducible UPLC–MS/MS method to analyze matrine, an anticancer compound, and to use it to investigate its biopharmaceutical and pharmacokinetic behaviors in rats. A sensitive and fast UPLC–MS/MS method was successfully applied to determine matrine in rat plasma, intestinal perfusate, bile, microsomes, and cell incubation media. The absolute oral bioavailability of matrine is 17.1 ± 5.4% at a dose of 2 mg/kg matrine. Matrine at 10 ?M was shown to have good permeability (42.5 × 10?6 cm/s) across the Caco-2 cell monolayer, and the ratio of PA–B to PB–A was approximately equal to 1 at two different concentrations (1 and 10 ?M). Perfusion study showed that matrine displayed significant differences (P < 0.05) in permeability at different intestinal regions. The rank order of permeability was ileum (highest, Pw = 6.18), followed by colon (Pw = 2.07), duodenum (Pw = 0.61) and jejunum (Pw = 0.52). Rat liver microsome studies showed that CYP and UGTs were not involved in matrine metabolism. In conclusion, a sensitive and reliable method capable of measuring matrine in a variety of matrixes was developed and successfully used to determine absolute oral bioavailability of matrine in rats, transport across Caco-2 cell monolayers, absorption in rat intestine, and metabolism in rat liver microsomes.

Yang, Zhen; Gao, Song; Yin, Taijun; Kulkarni, Kaustubh H.; Teng, Yang; You, Ming; Hu, Ming

2010-01-01

5

A Highly Sensitive Ultra Performance Liquid Chromatography-Tandem Mass Spectrometric (UPLC-MS/MS) Technique for Quantitation of Protein Free and Bound Efavirenz (EFV) in Human Seminal and Blood Plasma  

PubMed Central

A combined UPLC-tandem mass spectrometric (UPLC-MS/MS) technique has been validated for quantitation of protein free efavirenz (EFV) as well as total concentrations of EFV in human blood and seminal plasma. The analytical method possesses capabilities for concentration measurements of EFV ranging from 0.5 ng/ml to 10,000 ng/ml with an accuracy (%dev) of ?5.2% to 8.0% and precision (%CV) of <8%. Standard curves were linear with coefficients of variation (r2) > 0.98. The method employs a racemic fluorinated analog of EFV (F-EFV) as the internal standard. EFV and F-EFV were eluted from a reverse-phase UPLC column via gradient elution with detection via negative ion multiple reaction monitoring (MRM). EFV and F-EFV, respectively, were detected via the following MRM transitions: m/z 314.0 > 244.1 and m/z 298.0 > 227.9. The time required for the analysis of each sample was 8.0 minutes. The analytical technique is capable of a reliable detection limit of ~15–20 femtomoles of EFV injected on column.

Avery, Lindsay B.; Parsons, Teresa L.; Meyers, David J.; Hubbard, Walter C.

2010-01-01

6

High-throughput analysis of standardized pharmacokinetic studies in the rat using sample pooling and UPLC-MS/MS.  

PubMed

As a consequence of a continuous demand for increased throughput of pharmacokinetic (PK) studies, industries have introduced strategies to reduce the number of samples such as cassette analysis (pooling of samples after the in-life phase). Here, we have investigated whether relevant PK parameters change as a consequence of cassette analysis, and whether there are circumstances that disqualify this technique from being used. 22 compounds were intravenously and orally administered to parallel groups of 3 rats. Each compound was administered discretely. Equal volumes of three plasma samples corresponding to each time point of three discretely dosed rats with different compounds were pooled (cassette analysis). Samples were prepared by protein precipitation followed by UPLC-MS/MS analysis using pos/neg switching when required. With cassette analysis, 4 compounds, morphine, phenytoin, rofecoxib and diclofenac, showed high limit of quantification (LOQ) values after pooling, which led to less reliable PK analyses. Of all samples with contents above LOQ, about 5% could not be detected in pool samples compared to single samples. However, an excellent correlation was seen for all PK parameters when comparing the parameters obtained from discrete analysis versus those obtained from cassette analysis, although half life showed somewhat more scatter than the others. When PK parameters were grouped as low-medium-high, clearance, volume of distribution, half life and bioavailability were similar between discrete and cassette analysis for 90%, 86%, 95% and 90% of the total number of compounds tested, respectively. Some additional improvement was achieved if compounds with a low MS response were excluded. In summary, cassette analysis is an effective strategy to reduce samples without affecting the estimated PK parameters that are important for decision-making. PMID:21530131

Bueters, Tjerk; Dahlström, Jessie; Kvalvågnaes, Kristine; Betnér, Ingvar; Briem, Sveinn

2011-04-06

7

Determination of opiates and cocaine in urine by high pH mobile phase reversed phase UPLC–MS\\/MS  

Microsoft Academic Search

A fast and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC–MS\\/MS) method for the determination of opiates (morphine, codeine, 6-monoacetylmorphine (6-MAM), pholcodine, oxycodone, ethylmorphine), cocaine and benzoylecgonine in urine has been developed and validated. Sample preparation was performed by solid phase extraction (SPE) on a mixed mode cation exchange (MCX) cartridge. For optimized chromatographic performance with repeatable retention times, narrow

Thomas Berg; Elsa Lundanes; Asbjørg S. Christophersen; Dag Helge Strand

2009-01-01

8

Highly efficient sample preparation and quantification of constituents from traditional Chinese herbal medicines using matrix solid-phase dispersion extraction and UPLC-MS/MS.  

PubMed

In this work, a rapid and simple method based on matrix solid-phase dispersion (MSPD) and ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. Guge Fengtong preparation (GGFT), a traditional Chinese herbal medicine, was investigated for validation, and eight major constituents were determined including four saponins (protodioscin, protogracillin, pseudoprotodioscin and dioscin) and four gingerols (6-gingerol, 8-gingerol, 10-gingerol and 6-shogaol). Response surface methodology and desirability function were employed to optimize the extraction conditions, such as dispersant, dispersant/sample ratio, solvent concentration, and elution volume, of MSPD. Results showed that MSPD using C18 (1.75 g) as the dispersant material and methanol (89%, v/v) as the eluting solvent (12.00 mL) resulted in a high extraction efficiency. MSPD extraction had the advantages of combining extraction and clean-up in a single step, was less time consuming and required lower solvent volumes compared with conventional methods. Quantification of chemical compounds from GGFT preparations were performed using UPLC-MS/MS in multiple-reaction monitoring mode. The proposed method afforded a low limit of detection ranging from 0.02 to 0.40 ng for saponins and gingerols. For all the analytes, recoveries ranged from 80.9% to 103% and repeatabilities were acceptable with relative standard deviations of less than 6.81%. The proposed MSPD-UPLC-MS/MS method was successfully utilized to analyze five batches of GGFTs, and the results demonstrated that this method is simple, efficient and has potential to be applied for the quality control of herbal preparations. PMID:23443607

Cheng, Xiao-Lan; Qi, Lian-Wen; Wang, Qi; Liu, Xin-Guang; Boubertakh, Besma; Wan, Jin-Yi; Liu, E-Hu; Li, Ping

2013-04-21

9

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

2013-02-27

10

Development and validation of a fast and sensitive UPLC-MS/MS method for the quantification of six probe metabolites for the in vitro determination of cytochrome P450 activity.  

PubMed

A fast and sensitive UPLC-MS/MS method was developed and validated for the simultaneous quantification of six probe metabolites for the in vitro cytochrome P450 activity determination in hepatic microsomes from patients with hepatic impairment. The metabolites acetaminophen (CYP1A2), 4'-hydroxy-mephenytoin (CYP2C19), 4-hydroxy-tolbutamide (CYP2C9), dextrorphan (CYP2D6), 6-hydroxy-chlorzoxazone (CYP2E1) and 1-hydroxy-midazolam (CYP3A4), together with the internal standard chlorpropamide, were separated on a Waters Acquity UPLC BEH C18 column (50 mm × 2.1mm, 1.7 ?m particle size) with VanGuard pre-column (5 mm × 2.1mm, 1.7 ?m particle size). A short gradient elution (total run time of 5.25 min), using water with 0.1% formic acid (eluent A) and acetonitrile with 0.1% formic acid (eluent B) at a flow rate of 400 ?l/min, was used. The metabolites were detected with a triple quadrupole mass spectrometer in the multiple reaction monitoring mode. Two runs, one in the positive ionization mode and one in the negative mode, were necessary for the detection of all metabolites. The method was selective and showed good accuracy (84.59-109.83%) and between-day (RSD%<5.13%) and within-day (RSD%<9.60%) precision. The LOQ was in full accordance with the intended application, and no relative matrix effects were observed. Also, the sample incubation extracts were stable after three freeze-thaw cycles. The usability of the method was demonstrated by the incubation of pediatric microsomes with subsequent quantification of the formed metabolites and CYP activity calculation. PMID:22284482

De Bock, Lies; Boussery, Koen; Colin, Pieter; De Smet, Julie; T'jollyn, Huybrecht; Van Bocxlaer, Jan

2011-12-09

11

Folate analysis in foods by UPLC-MS/MS: development and validation of a novel, high throughput quantitative assay; folate levels determined in Australian fortified breads.  

PubMed

An ultra-performance liquid chromatography-tandem mass spectrometry method was developed, optimised and validated for the quantification of synthetic folic acid (FA), also called pteroyl-L: -glutamic acid or vitamin B9 and naturally occurring 5-methyltetrahydrofolate (5-MTHF) found in folate-fortified breads. Optimised sample preparation prior to analysis involved addition of (13)C(5) labelled internal standards, treatments with ?-amylase and rat serum, solid-phase extraction using aromatic-selective cartridges and ultra-filtration. Analytes were separated on a Waters ACQUITY HSS T3 column during a 6-min run and analysed by positive ion electrospray selected reaction monitoring MS/MS. Standard calibration curves for the two analytes were linear over the range of 0.018-14 ?g FA/g of fresh bread (r(2) = 0.997) and 9.3-900 ng 5-MTHF/g of fresh bread (r(2) = 0.999). The absolute recoveries were 90% and 76% for FA and 5-MTHF, respectively. Intra-day coefficients of variation were 3% for FA and 18% for 5-MTHF. The limit of detection was 9.0 ng/g for FA and 4.3 ng/g for 5-MTHF, determined using pre-extracted tapioca starch as the blank matrix. The assay is rugged, fast, accurate and sensitive, applicable to a variety of food matrices and is capable of the detection and quantification of the naturally occurring low levels of 5-MTHF in wheat breads. The findings of this study revealed that the FA range in Australian fortified breads was 79-110 ?g/100 g of fresh bread and suggest that the flour may not have the mandated FA fortification level (200-300 ?g/100 g of flour), though this cannot be determined conclusively from experimental bread data alone, as variable baking losses have been documented by other authors. PMID:21667347

Chandra-Hioe, Maria V; Bucknall, Martin P; Arcot, Jayashree

2011-06-13

12

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

2013-04-11

13

Global metabolic profiling procedures for urine using UPLC–MS  

Microsoft Academic Search

The production of 'global' metabolite profiles involves measuring low molecular-weight metabolites (<1 kDa) in complex biofluids\\/tissues to study perturbations in response to physiological challenges, toxic insults or disease processes. Information-rich analytical platforms, such as mass spectrometry (MS), are needed. Here we describe the application of ultra-performance liquid chromatography–MS (UPLC–MS) to urinary metabolite profiling, including sample preparation, stability\\/storage and the selection

Ian D Wilson; Helen Gika; Georgios Theodoridis; Robert S Plumb; John Shockcor; Elaine Holmes; Jeremy K Nicholson; Elizabeth J Want

2010-01-01

14

HILIC-UPLC-MS for exploratory urinary metabolic profiling in toxicological studies.  

PubMed

Hydrophilic interaction ultra performance liquid chromatography (HILIC-UPLC) permits the analysis of highly polar metabolites, providing complementary information to reversed-phase (RP) chromatography. HILIC-UPLC-TOF-MS was investigated for the global metabolic profiling of rat urine samples generated in an experimental hepatotoxicity study of galactosamine (galN) and the concomitant investigation of the protective effect of glycine. Within-run repeatability and stability over a large sample batch (>200 samples, 60 h run-time) was assessed through the repeat analysis of a quality control sample. Following system equilibration, excellent repeatability was observed in terms of retention time (CV < 1.7%), signal intensity (CV < 14%), and mass variability (<0.005 amu), providing a good measure of reproducibility. Classification of urinary metabolic profiles according to treatment was observed, with significant changes in specific metabolites after galN exposure, including increased urocanic acid, N-acetylglucosamine, and decreased 2-oxoglutarate. A novel finding from this HILIC-UPLC-MS approach was elevated urinary tyramine in galN-treated rats, reflecting disturbed amino acid metabolism. These results show HILIC-UPLC-MS to be a promising method for global metabolic profiling, demonstrating high within-run repeatability, even over an extended run time. Retention of polar endogenous analytes and xenobiotic metabolites was improved compared with RP studies, including galN, N-acetylglucosamine, oxoglutarate, and urocanic acid, enhancing metabolome coverage and potentially improving biomarker discovery. PMID:21142126

Spagou, Konstantina; Wilson, Ian D; Masson, Perrine; Theodoridis, Georgios; Raikos, Nikolaos; Coen, Muireann; Holmes, Elaine; Lindon, John C; Plumb, Robert S; Nicholson, Jeremy K; Want, Elizabeth J

2010-12-13

15

UPLC-MS/MS measurement of S-nitrosoglutathione (GSNO) in human plasma solves the S-nitrosothiol concentration enigma.  

PubMed

We developed and validated a fast UPLC-MS/MS method with positive electrospray ionization (ESI+) for the quantitative determination of S-nitrosoglutathione (GSNO) in human plasma. We used a published protocol for the inactivation of plasma ?-glutamyltransferase (?GT) activity by using the ?GT transition inhibitor serine/borate and the chelator EDTA for the stabilization of GSNO, and N-ethylmaleimide (NEM) to block SH groups and to avoid S-transnitrosylation reactions which may diminish GSNO concentration. S-[(15)N]Nitrosoglutathione (GS(15)NO) served as internal standard. Fresh blood was treated with NEM/serine/borate/EDTA, plasma spiked with GS(15)NO (50nM) was ultrafiltered (cut-off 10kDa) and 10?L aliquots of the ultrafiltrate were analyzed by UPLC-MS/MS. Five HILIC columns and an Acquity UPLC BH amide column were tested. The mobile phase was acetonitrile-water (70:30, v/v), contained 20mM ammonium formate, had a pH value of 7, and was pumped isocratically (0.5mL/min). The Nucleoshell column allowed better LC performance and higher MS sensitivity. The retention time of GSNO was about 1.1min. Quantification was performed by selected-reaction monitoring the mass transition m/z 337 ([M+H](+))?m/z 307 ([M+H(14)NO](+)) for GSNO (i.e., GS(14)NO) and m/z 338 ([M+H](+))?m/z 307 ([M+H(15)NO](+)) for GS(15)NO. NEM/serine/borate/EDTA was found to stabilize GSNO in human plasma. The method was validated in human plasma (range, 0-300nM) using 50nM GS(15)NO. Accuracy and precision were in generally acceptable ranges. A considerable matrix effect was observed, which was however outweighed by the internal standard GS(15)NO. In freshly prepared plasma from heparinized blood donated by 10 healthy subjects, no endogenous GSNO was determined above 2.8nM, the limit of quantitation (LOQ) of the method. This study challenges previously reported GSNO plasma concentrations being far above the present method LOQ value and predicts that the concentration of low-molecular-mass and high-molecular-mass S-nitrosothiols are in the upper pM- and lower nM-range, respectively. PMID:23453822

Tsikas, Dimitrios; Schmidt, Mario; Böhmer, Anke; Zoerner, Alexander A; Gutzki, Frank-Mathias; Jordan, Jens

2013-02-04

16

Rapid quantitative analysis of clarithromycin in rat plasma by UPLC-MS/MS after intravenous injection of the clarithromycin-loaded ultrafine PLGA nanoparticles.  

PubMed

Nanoparticles were designed to encapsulate drugs to alter their pharmacological behaviors, therefore, it is very essential to monitor the pharmacokinetic profile of drug encapsulated in nanoparticles in order to clarify and predict their efficacy and side effects. In this paper, we reported a simple, rapid ?-elution 96-well solid phase extraction (?SPE) method combining with ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for determination of nanoformulated drug in rat plasma. This method presented satisfactory results in terms of sensitivity, precision, accuracy, and recovery, for the first time, of quantitatively analyzing clarithromycin (CLA) in rat plasma after intravenous administration CLA-loaded ultrafine PLGA nanoparticles for pharmacokinetic study. This method has been proved to be fast, reliable and reproducible to accurately analyze drug encapsulated in polymeric nanoparticles sample for a pharmacokinetic study. PMID:22483396

Wang, Yu-Jing; Wu, Yi-Ting; Lin, Jia-Yi; Chu, Chih-Hung; Huang, Hsin-Ying; Wang, Yu-Chao; Chen, Jen-Kun; Yang, Chung-Shi

2012-03-22

17

Comparative analysis of quinolizidine alkaloids from different parts of Sophora alopecuroides seeds by UPLC-MS/MS.  

PubMed

The seeds of Sophora alopecuroides L. have been utilized as a crude drug in China for thousands of years. Quinolizidine alkaloids are the main bioactive components of this plant. To determine the distribution and content of quinolizidine alkaloids in different seed organs (seed coat and cotyledon), a reliable method has been established using ultra-high-performance liquid chromatography coupled with a triple quadrupole electrospray tandem mass spectrometry (UPLC-MS/MS). Seven constituents, namely cytisine, oxymatrine, oxysophocarpine, sophoridine, sophoramine, matrine, and sophocarpine, were simultaneously determined in 10 min. The proposed method was fully validated in terms of linearity, sensitivity, precision, repeatability as well as recovery. The analysis results showed there were remarkable differences in the distribution and contents of the chemical markers between seed coat and cotyledon. The established approach could be helpful for the quality control of S. alopecuroides seeds, and also for the determination of this type class of alkaloids in other medicinal herbs. The present study can provide necessary information for the rational utilization of S. alopecuroides resources. PMID:22613581

Wang, Hanqing; Guo, Sheng; Qian, Dawei; Qian, Yefei; Duan, Jin-ao

2012-04-25

18

Graphene based pipette tip solid phase extraction of marine toxins in shellfish muscle followed by UPLC-MS/MS analysis.  

PubMed

Graphene is a novel carbonic material with great potentials for the use as sorbent due to its ultrahigh surface area. Herein, we report the use of graphene as sorbent in solid-phase extraction (SPE) using pipette tip as cartridge namely GPT-SPE, together with ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), for the analysis of lipophilic marine toxins (LMTs), including yessotoxins (YTX), okadaic acid (OA), dinophysistoxin-1 (DTX1), gymnodimine (GYM), spirolides-1 (SPX1), pectenotoxin-2 (PTX2) and azaspiracid-1 (AZA1) in shellfish. The GPT-SPE procedure was optimized and the performance of graphene was fully validated. Results with high-sensitivity and good reproducibility was obtained and compared with that of other sorbents like C18 silica, multi-walled carbon nanotubes (MWCNTs), commercial Oasis HLB, and Strata-X for the extraction of LMTs, which showed superiority and advantages of graphene, such as good recoveries, stability and compatibility with various solvents. In order to exhibit the potentials of graphene as an excellent sorbent material, 67 mussel samples from six coastal cities of China were analyzed. OA was found to be the dominant contaminant, while YTX was also detected with low level. PMID:24148472

Shen, Qing; Gong, Like; Baibado, Joewel T; Dong, Wei; Wang, Yixuan; Dai, Zhiyuan; Cheung, Hon-Yeung

2013-07-26

19

Detection and quantification of cocaine and benzoylecgonine in meconium using solid phase extraction and UPLC/MS/MS.  

PubMed

The simultaneous determination and quantification of cocaine and its major metabolite, benzoylecgonine, in meconium using UPLC-MS/MS is described. Ultra-performance liquid chromatography (UPLC) is an emerging analytical technique which draws upon the principles of chromatography to run separations at higher flow rates for increased speed, while simultaneously achieving superior resolution and sensitivity. Extraction of cocaine and benzoylecgonine from the homogenized meconium matrix was achieved with a preliminary protein precipitation or protein 'crash' employing cold acetonitrile, followed by a mixed mode solid phase extraction (SPE). Following elution from the SPE cartridge, eluents were dried down under nitrogen, reconstituted in 200 microL of DI water:acetonitrile (ACN) (75:25), and injected onto the UPLC/MS/MS for analysis. The increased speed and separation efficiency afforded by UPLC, allowed for the separation and subsequent quantification of both analytes in less than 2 min. Analytes were quantified using multiple reaction monitoring (MRM) and six-point calibration curves constructed in negative blood. Limits of detection for both analytes were 3 ng/g and the lower limit of quantitation (LLOQ) was 30 ng/g. PMID:20077069

Gunn, Josh; Kriger, Scott; Terrell, Andrea R

2010-01-01

20

Bioactivity fingerprint analysis of cyclooxygenase-2 ligands from radix Aconiti by ultrafiltration-UPLC-MS(n.).  

PubMed

A novel fingerprinting method, bioactivity fingerprint analysis, based on an ultrafiltration-ultraperformance liquid chromatography-multistage tandem mass spectrometry (UPLC-MS (n) ) method is proposed for the quality control of herbal medicines from the bioactivity viewpoint concerning the efficacy of herbal medicines. The bioactivity fingerprints reflecting the anti-inflammatory activities of radix Aconiti and radix Aconiti preparata were established. With use of ultrafiltration UPLC-MS (n) , 11 cyclooxygenase-2 ligands from radix Aconiti preparata and 14 cyclooxygenase-2 ligands from radix Aconiti were found after incubation with cyclooxygenase-2. Twelve of the cyclooxygenase-2 ligands were identified by the ultraperformance UPLC-MS (n) method. The enrichment factor of each peak in the bioactivity fingerprint was calculated and was demonstrated to be characteristic, which makes bioactivity fingerprint analysis for the quality control of herbal medicines possible from the viewpoint of their bioactivities. PMID:23831827

Zhu, Hongbin; Liu, Shu; Li, Xue; Song, Fengrui; Liu, Zhiqiang; Liu, Shuying

2013-07-07

21

UPLC-MS/MS quantification of nanoformulated ritonavir, indinavir, atazanavir, and efavirenz in mouse serum and tissues  

PubMed Central

Animal pharmacokinetic and tissue distribution assays of antiretroviral therapeutic drugs require accurate drug quantification in biological fluids and tissues. Here we report a simple, rapid, and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantification of commonly used antiretroviral drugs ritonavir (RTV), indinavir (IDV), atazanavir (ATV), and efavirenz (EFV) in mouse serum and tissues (liver, kidney, lung, and spleen). These antiretroviral drugs are currently the cornerstones of common therapeutic regimens for human immunodeficiency virus (HIV) infection. Chromatographic separation was achieved using a gradient mobile phase (5% acetonitrile in methanol and 7.5 mM ammonium acetate (pH 4.0)) on an ACQUITY UPLC® BEH Shield RP 18 column. All compounds eluted within a seven min run time. Lopinavir was used as an internal standard. Detection was achieved by dual positive and negative ionization modes on a quadrupole linear ion trap hybrid mass spectrometer with an electrospray ionization (ESI) source. The dynamic range was 0.2–1000 ng/mL for RTV, IDV, and ATV, and 0.5–1000 for EFV. The method was validated and showed high and consistent intra-day and inter-day accuracy and precision for all analytes. This method is used to support the preclinical development studies of targeted- and sustained-release combination ART (nanoART). The current data demonstrate a 1.5–4 fold increase in serum and tissue AUC of nanoformulated ATV, RTV, and EFV administered to mice when compared to native drug. In addition, the tested formulation enhanced exposure of the same anti-HIV drugs in mouse tissues.

Huang, Jiangeng; Gautam, Nagsen; Bathena, Sai Praneeth R; Roy, Upal; McMillan, JoEllyn; Gendelman, Howard E.; Alnouti, Yazen

2011-01-01

22

A fast one-step extraction and UPLC-MS/MS analysis for E2/D 2 series prostaglandins and isoprostanes.  

PubMed

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 the 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. PMID:23400687

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

2013-02-12

23

Inhibition of the isoprenoid biosynthesis pathway; detection of intermediates by UPLC-MS/MS.  

PubMed

The isoprenoid biosynthesis pathway provides the cell with a variety of compounds which are involved in multiple cellular processes. Inhibition of this pathway with statins and bisphosphonates is widely applied in the treatment of hypercholesterolemia and metabolic bone disease, respectively. In addition, since isoprenylation of proteins is an important therapeutic target in cancer research there is interest in interfering with isoprenoid biosynthesis, for which new inhibitors to block farnesylation and geranylgeranylation of small GTPases are being developed. We recently developed a sensitive method using UPLC-MS/MS that allows the direct detection and quantification of all intermediates of the mevalonate pathway from MVA to GGPP which can be used to verify the specificity of inhibitors of the isoprenoid biosynthesis pathway. We here investigated the specificity of several inhibitors of the isoprenoid biosynthesis pathway in HepG2 cells, fibroblasts and lymphoblasts. The nitrogen-containing bisphosphonates pamidronate and zoledronate specifically inhibit farnesyl pyrophosphate synthase indicated by the accumulation of IPP/DMAPP. However, zaragozic acid A, a squalene synthase inhibitor, causes an increase of MVA in addition to the expected increase of FPP. Analysis of isoprenoid intermediate profiles after incubation with 6-fluoromevalonate showed a very nonspecific result with an increase in MVA, MVAP, MVAPP and IPP/DMAPP. These results show that inhibitors of a particular enzyme of the isoprenoid biosynthesis pathway can have additional effects on other enzymes of the pathway either direct or indirect through accumulation of isoprenoid intermediates. Our method can be used to test new inhibitors and their effect on overall isoprenoid biosynthesis. PMID:21237288

Henneman, Linda; van Cruchten, Arno G; Kulik, Willem; Waterham, Hans R

2011-01-13

24

Allantoin in Human Urine Quantified by UPLC-MS/MS  

PubMed Central

Uric acid is a potent antioxidant and scavenger of singlet oxygen and other radicals in humans. Allantoin, the predominant product of free radical-induced oxidation of uric acid is efficiently excreted in the urine and has potential as a biomarker of oxidative stress. We developed a rapid and specific assay for urinary allantoin using ultra performance liquid chromatography-tandem mass spectrometry suitable for high-throughput clinical studies. The method required minimal sample preparation, was accurate (mean error 6%), precise (intra- and inter-day imprecision: <8%) and sensitive (limit of detection: 0.06 pmol). Allantoin levels measured in control samples were comparable to literature values.

Tolun, Adviye A.; Zhang, Haoyue; Ii'yasova, Dora; Sztaray, Judit; Young, Sarah P.; Millington, David S.

2010-01-01

25

Removal of malathion from aqueous solution using De-Acidite FF-IP resin and determination by UPLC-MS/MS: Equilibrium, kinetics and thermodynamics studies.  

PubMed

In the present study, De-Acidite FF-IP resin was used to remove a highly toxic and persistent organophosphorus pesticide (malathion) from the aqueous solution. Batch experiments were performed as a function of various experimental parameters such as effect of pH (2-10), contact time (10-120min), resin dose (0.05-0.5g), initial malathion concentration (0.5-2.5µgmL(-1)) and temperature (25-65°C). The concentration of malathion was determined using a sensitive, selective and rapid ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. The uptake rate of malathion on De-Acidite FF-IP resin was rapid and equilibrium established within 40min. Kinetics studies showed better applicability for pseudo-second-order model. The equilibrium data was fitted to Langmuir and Freundlich isotherm models and the isotherm constants were calculated for malathion. The values of thermodynamic parameters (?G(0), ?H(0) and ?S(0)) were computed from the Van't Hoff plot of lnKC vs. 1/T which showed that the adsorption of malathion was feasible, endothermic and spontaneous. The regeneration studies were carried out which demonstrated a decrease in the recovery of malathion from 95% to 68% after five consecutive cycles. Breakthrough and exhaustive capacities of malathion were found to be 1.25mgg(-1) and 3.5mgg(-1), respectively. PMID:24054556

Naushad, Mu; Alothman, Z A; Khan, M R

2013-04-16

26

Pharmacokinetics of Dibutyl Phthalate (DBP) in the Rat Determined by UPLC-MS/MS.  

PubMed

Dibutyl phthalate (DBP) is commonly used to increase the ?exibility of plastics in industrial products. However, several plasticizers have been illegally used as clouding agents to increase dispersion of aqueous matrix in beverages. This study thus develops a rapid and validated analytical method by ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) for the evaluation of pharmacokinetics of DBP in free moving rats. The UPLC-MS/MS system equipped with positive electrospray ionization (ESI) source in multiple reaction monitoring (MRM) mode was used to monitor m/z 279.25?148.93 transitions for DBP. The limit of quanti?cation for DBP in rat plasma and feces was 0.05 µg/mL and 0.125 µg/g, respectively. The pharmacokinetic results demonstrate that DBP appeared to have a two-compartment model in the rats; the area under concentration versus time (AUC) was 57.8 ± 5.93 min ?g/mL and the distribution and elimination half-life (t(1/2,?) and t(1/2,?)) were 5.77 ± 1.14 and 217 ± 131 min, respectively, after DBP administration (30 mg/kg, i.v.). About 0.18% of the administered dose was recovered from the feces within 48 h. The pharmacokinetic behavior demonstrated that DBP was quickly degraded within 2 h, suggesting a rapid metabolism low fecal cumulative excretion in the rat. PMID:23344044

Chang, Li-Wen; Hou, Mei-Ling; Tsai, Tung-Hu

2013-01-04

27

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

PubMed

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. PMID:23529861

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

2013-04-24

28

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

29

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

30

Separation and detection of smokeless powder additives by ultra performance liquid chromatography with tandem mass spectrometry (UPLC/MS/MS).  

PubMed

A reversed phase gradient ultra performance liquid chromatography tandem mass spectrometry (UPLC/MS/MS) method has been developed for the analysis of smokeless powders. A total of 20 different components were separated by UPLC and detected by MS/MS in multiple reaction monitoring (MRM) mode. These compounds included diphenylamines, centralites, nitrotoluenes, nitroglycerin, and various phthalates. Simultaneous positive and negative electrospray ionization (ESI) was used along with negative atmospheric pressure chemical ionization (APCI) to detect all compounds in a single analysis. Analysis times were under 8 min with a gradient of 10-73% organic at a flow rate of 0.500 mL/min. With this method, ultraviolet and MRM limits of detection ranging from 0.08 to 2.6 ng and 0.4-64 ng injected were achieved. Commercially available smokeless powders were also extracted with methylene chloride and characterized using the developed UPLC/MS/MS method. The procedure permits the determination of compositional differences between different brands as well as lot-to-lot variations. PMID:23550595

Thomas, Jennifer L; Lincoln, Danielle; McCord, Bruce R

2013-04-01

31

Simultaneous determination of bioactive components in essential oil of Xiang-Fu-Si-Wu Formula in Beagle dog plasma by UPLC-MS/MS and its application to pharmacokinetics.  

PubMed

A highly sensitive and rapid ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been developed and validated for simultaneous quantification of the three main bioactive compounds, i.e., ligustilide, dehydrocostuslactone and ?-cyperone in dog plasma after oral administration of the essential oil of Xiang-Fu-Si-Wu Formula (XEO). Clarithromycin was used as an internal standard (IS). 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 0.4mLmin(-1), using 0.1% formic acid-acetonitrile as mobile phase. The MS/MS ion transit ions monitored were 190.5?90.9 for ligustilide, 231.1?185.1 for dehydrocostuslactone, 219.2?123.0 for ?-cyperone and 748.5?158.1 for IS. Method validation was performed as per Food and Drug Administration guidelines and the results met the acceptance criteria. The lower limit of quantification (LLOQ) achieved was 5.12ng/mL for ligustilide, 1.06ng/mL for dehydrocostuslactone and 1.89ng/mL for ?-cyperone, respectively, and the calibration curves obtained were linear (r>0.99) over the concentration range approximately 1-1000ng/mL. The intra- and inter-day precision was less than 15% and the accuracy was within ±9.2%. After validation, this method was successfully applied to a pharmacokinetic study where dogs were orally given 0.3g/kg XEO, equivalent to 183.6mg/kg of ligustilide, 5.0mg/kg of dehydrocostuslactone and 26.2mg/kg of ?-cyperone, respectively. PMID:23665892

Liu, Pei; Li, Zhenhao; Qian, Dawei; Li, Wei; Shang, Er-Xin; Duan, Jin-Ao

2013-04-20

32

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

2013-08-17

33

A validated, rapid UPLC-MS/MS method for simultaneous ivabradine, reboxetine, and metoprolol analysis in human plasma and its application to clinical trial samples.  

PubMed

A recent clinical trial assessing human autonomic cardiovascular regulation applied pacemaker channel inhibition with ivabradine, norepinephrine transporter blockade with reboxetine, and beta-adrenoreceptor blockade with metoprolol. To verify patient adherence, we developed and validated a fast UPLC-MS/MS assay measuring all three compounds simultaneously. Deuterium-labeled drugs, d3-ivabradine, d5-reboxetine and d7-metoprolol, served as internal standards. Sample preparation of 200?L human plasma consisted of a single liquid-liquid extraction step by means of ethyl acetate. Chromatographic separation was performed on a 50-mm long BEH C18 column with gradient elution using a mixture of water and methanol each containing 2mM ammonium acetate over 4.5min. The mass spectrometer was operated in the positive electrospray ionization (ESI+) mode. Characteristic product ions resulting from collision-induced dissociation of unlabeled and deuterium-labeled drugs with argon were used for quantification in the selected-reaction monitoring mode. We validated the method according to the European Medicines Agency (EMA) guideline on bioanalytical method validation over the range from 1ng/mL to 500ng/mL for all three analytes. Linear responses with correlation coefficients>0.99 over that range were acquired. The LOQ value was 1ng/mL for each drug. Regulatory criteria for accuracy (80-120%) and precision (RSD<15%) were met for all drugs. The internal standard-normalized matrix factor was close to 1 for low and high analyte concentrations. We successfully measured ivabradine, reboxetine, and metoprolol concentrations in 107 human plasma samples from a clinical trial. Quality control samples processed in parallel confirmed the method's reliability in a clinical setting. PMID:23434314

Zoerner, Alexander A; Schroeder, Christoph; Kayacelebi, Arslan Arinc; Suchy, Maria T; Gutzki, Frank-Mathias; Stichtenoth, Dirk O; Tank, Jens; Jordan, Jens; Tsikas, Dimitrios

2013-01-29

34

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

2012-02-08

35

Fast simultaneous determination of multiple water-soluble vitamins and vitamin-like compounds in infant formula by UPLC-MS\\/MS  

Microsoft Academic Search

Fortification of infant formula provides the sole source of nutrition for bottle-fed baby; therefore, particular attention should be paid to ensure an adequate and balanced intake of vitamins, which cannot be synthesized by the body, but essential for the normal growth and functioning of human body. An Ultra Performance LC-Tandem Mass Spectrometry (UPLC-MS\\/MS) method was developed for fast simultaneous determination

Hong Zhang; Si Chen; Wenjuan Liao; Yiping Ren

36

A UPLC-MS/MS method for the simultaneous plasma quantification of all isomeric forms of the new anti-HCV protease inhibitors boceprevir and telaprevir.  

PubMed

HCV infection affects over 170 milions people in the world. Up to now standard-of-care therapy consisted in ribavirin plus interferon-? 2a or 2b. Recently, two new Direct Acting Antivirals (DAA), inhibitors of NS3 HCV protease, have been developed and approved for the routine use on HCV genotype 1 infected patients: boceprevir and telaprevir. Protease inhibitors show complex pharmacokinetics (strong metabolism of both drugs by CYP3A and drug interactions), they require a TID dosage and, furthermore, they are present in plasma patients in two different isomeric forms. In this work, we developed and validated an UPLC-tandem mass spectrometry assay method capable of monitoring the telaprevir and boceprevir concentrations in plasma, discriminating each isomer of both drugs. Blank plasma used for Standards and QCs preparation, was obtained from blood of healthy donors. The calibration curves for each isomer of telaprevir and boceprevir were linear in a range from 46.87 ng/mL to 6000 ng/mL and from 23.43 to 3000 ng/mL, respectively (mean r(2)>0.998 for all analytes). QCs at three different concentration were prepared: High, Medium and Low. Each Standard, QC and patient sample was treated with a protein precipitation protocol with a solution containing acidified acetonitrile and Internal Standard (6,7-Dimethyl-2,3-di(2-pyridyl)quinoxaline). An aliquot of supernatant was diluted and then directly analyzed by reverse-phase UPLC-MS/MS. Accuracy (mean 98.47%), intra-day (mean <5.21%) and inter-day (mean <7.57%) precision for telaprevir and boceprevir quality controls fitted all FDA guidelines. All compounds resulted stable in our method conditions and the extraction procedure showed a recovery near to 100%. Finally, we tested this method by monitoring plasma concentrations in 9 HCV+ patients, for each triple combined therapy, with good results. The observed median ratio between S and R isomers for boceprevir and telaprevir were 1.22 (IQR 1.10-1.33) and 1.52 (IQR 1.21-1.67), respectively. The use of this simple assay method could be an important tool for management of HCV-1 DAAs treated patients. PMID:23501442

D'Avolio, Antonio; De Nicolò, Amedeo; Agnesod, Danilo; Simiele, Marco; Mohamed Abdi, Adnan; Dilly Penchala, Sujan; Boglione, Lucio; Cariti, Giuseppe; Di Perri, Giovanni

2013-02-27

37

Determination of six Alternaria toxins with UPLC-MS\\/MS and their occurrence in tomatoes and tomato products from the Swiss market  

Microsoft Academic Search

An ultra performance liquid chromatography (UPLC)-tandem mass spectrometry (MS\\/MS) method was developed for the determination\\u000a of the Alternaria toxins tenuazonic acid, alternariol, alternariol monomethyl ether, altenuene, altertoxin I and tentoxin. Owing to its instability,\\u000a altenusin could not be determined. The sample preparation includes an acidic acetonitrile\\/water\\/methanol extraction, followed\\u000a by SPE clean-up step, before injection into the UPLC-MS\\/MS system. The separation

Jürg Noser; Patrick Schneider; Martin Rother; Hansruedi Schmutz

38

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

2013-01-29

39

Validation of a fast method for quantitative analysis of elvitegravir, raltegravir, maraviroc, etravirine, tenofovir, boceprevir and 10 other antiretroviral agents in human plasma samples with a new UPLC-MS/MS technology.  

PubMed

Therapeutic drug monitoring (TDM) of antiretrovirals requires accurate and precise analysis of plasma drug concentrations. This work describes a simple, fast and sensitive UPLC-MS/MS method for determination of the commonly used protease inhibitors such as amprenavir, atazanavir, darunavir, indinavir, lopinavir, ritonavir, saquinavir and tipranavir, tenofovir a nucleoside reverse transcriptase inhibitor (NRTI), the non-NRTI such as efavirenz, nevirapine, etravirine, the CCR5 antagonist maraviroc as well as the more recent antiretrovirals, the integrase inhibitors such as raltegravir, elvitegravir and the new direct acting anti-HCV boceprevir. Adapted deuterated internal standard was added to plasma aliquots (100?l) prior to protein precipitation with methanol and acetonitrile. This method employed ultra-performance liquid chromatography coupled to tandem mass spectrometry with electrospray ionization mode. All compounds eluted within 4.2-min run time. Calibration curves were validated, with correlation coefficients (r(2)) higher than 0.997, for analysis of therapeutic concentrations reported in the literature. Inter- and intra-assay variations were <15%. Evaluation of accuracy shows a deviation <15% from target concentration at each quality control level. No significant matrix effect was observed for any of the antiretroviral studied. This new validated method fulfills all criteria for TDM of 15 antiretrovirals and boceprevir drugs and was successfully applied in routine TDM of antiretrovirals. PMID:23995753

Djerada, Zoubir; Feliu, Catherine; Tournois, Claire; Vautier, Damien; Binet, Laurent; Robinet, Arnaud; Marty, Hélène; Gozalo, Claire; Lamiable, Denis; Millart, Hervé

2013-08-12

40

Simultaneous determination of pimpinellin, isopimpinellin and phellopterin in rat plasma by a validated UPLC-MS/MS and its application to a pharmacokinetic study after administration of Toddalia asiatica extract.  

PubMed

A rapid and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for simultaneous determination of three bioactive coumarins of Toddalia asiatica extract including pimpinellin, isopimpinellin and phellopterin in rat plasma for the first time. Phenacetin was used as the internal standard (IS). Plasma samples were extracted by liquid-liquid extraction with methyl tert-butyl ether. The chromatographic separation was carried out on an ACQUITY UPLC™ BEH C?? column with an isocratic mobile phase consisting of methanol-5 mmol/L ammonium acetate (65:35, v/v). 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. The method was linear for all analytes over investigated range with all correlation coefficients greater than 0.9942. The lower limits of quantification (LLOQ) were 25.0 ng/mL for pimpinellin, 10.0 ng/mL for isopimpinellin and 5.00 ng/mL for phellopterin. The intra- and inter-day precision (RSD%) was within 12% and the accuracy (RE%) ranged from -2.3% to 5.5%. The rapid and sensitive method was fully validated and successfully applied to the pharmacokinetic study of pimpinellin, isopimpinellin and phellopterin in rats following oral administration of Toddalia asiatica extract. PMID:22418072

Liu, Zhigang; Jiang, Minyan; Lu, Xiumei; Qin, Feng; Song, Yang; Wen, Jing; Li, Famei

2012-02-22

41

A UPLC-MS/MS method for qualification of quercetin-3-O-?-D-glucopyranoside-(4?1)-?-L-rhamnoside in rat plasma and application to pharmacokinetic studies.  

PubMed

A sensitive and accurate ultra-performance liquid chromatography coupled with triple quadrupole mass (UPLC-MS/MS) method was developed for the determination of quercetin-3-O-?-D-glucopyranoside-(4?1)-?-L-rhamnoside (QGR) in rat plasma using rutin as internal standard. Chromatographic separation was achieved on a Acquity BEH C18 column (100 mm × 2.1 mm, 1.7 ?m) with a gradient elution of acetonitrile and 0.10% formic acid (v/v) at a flow rate of 0.4 mL/min. QGR and rutin were detected using electrospray negative ionization mass spectrometry in the multiple reaction monitoring (MRM) mode. The method demonstrated good linearity and did not show any endogenous interference with the QGR and rutin peaks. This method was successfully applied to a pharmacokinetic study of QGR in rats after intravenous (20 mg/kg) and oral (40 mg/kg) administration, and the results showed that the compound was poorly absorbed, with an absolute bioavailability of approximately 3.41%. PMID:23470334

Yao, Xin; Zhou, Guisheng; Tang, Yuping; Li, Zhenhao; Su, Shulan; Qian, Dawei; Duan, Jin-Ao

2013-03-07

42

Identification and quantitation of cocaine, benzoylecgonine, and cocaethylene in blood, serum, and plasma using ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS).  

PubMed

Cocaine is a widely abused stimulant. Numerous methods exist for the identification of the drug, or more commonly, one of its metabolites in urine. Urine testing is useful for most cases, but it is necessary to use other matrices in forensic situations and when subjects are anuric. We describe a novel method for the analysis of cocaine, benzoylecgonine, and cocaethylene in blood, serum, and plasma utilizing ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). Sample preparation has been minimized to a simple deproteinization step in which each specimen is mixed with an acetonitrile-internal standard mixture. The method has excellent precision across the linear range of 25-2,000 ng/mL for each analyte. With a run-time of 4 min, this method provides a significant improvement over traditional GC/MS methods. PMID:20077068

Kriger, Scott; Gunn, Josh; Terrell, Andrea R

2010-01-01

43

Determination of six Alternaria toxins with UPLC-MS/MS and their occurrence in tomatoes and tomato products from the Swiss market.  

PubMed

An ultra performance liquid chromatography (UPLC)-tandem mass spectrometry (MS/MS) method was developed for the determination of the Alternaria toxins tenuazonic acid, alternariol, alternariol monomethyl ether, altenuene, altertoxin I and tentoxin. Owing to its instability, altenusin could not be determined. The sample preparation includes an acidic acetonitrile/water/methanol extraction, followed by SPE clean-up step, before injection into the UPLC-MS/MS system. The separation was made on an Acquity UPLC column using a water/acetonitrile gradient with ammonium hydrogen carbonate as a modifier. Matrix compounds of real samples led to enhancement as well as suppression of the target compounds, depending on analyte and matrix. The recoveries were between 58 and 109% at a level of 10 ?g/kg. Eighty-five tomato products, consisting of peeled and minced tomatoes, soup and sauces, tomato purées and concentrates, ketchup as well as dried and fresh tomatoes, were taken from the Swiss market in 2010. Tenuazonic acid was found most frequently (81 out of 85 samples) and in the highest levels of up to 790 ?g/kg. Alternariol and alternariol monomethyl ether were found in lower concentrations, ranging from <1 to 33 ?g/kg for alternariol and <5 to 9 ?g/kg for alternariol monomethyl ether. Only a few samples were positive for altenuene and tentoxin. Altertoxin I was never detected. PMID:23605928

Noser, Jürg; Schneider, Patrick; Rother, Martin; Schmutz, Hansruedi

2011-06-22

44

Development and validation of a sample stabilization strategy and a UPLC–MS\\/MS method for the simultaneous quantitation of acetylcholine (ACh), histamine (HA), and its metabolites in rat cerebrospinal fluid (CSF)  

Microsoft Academic Search

A UPLC–MS\\/MS assay was developed and validated for simultaneous quantification of acetylcholine (ACh), histamine (HA), tele-methylhistamine (t-mHA), and tele-methylimidazolacetic acid (t-MIAA) in rat cerebrospinal fluid (CSF). The biological stability of ACh in rat CSF was investigated. Following fit-for-purpose validation, the method was applied to monitor the drug-induced changes in ACh, HA, t-mHA, and t-MIAA in rat CSF following administration of

Yanhua Zhang; F. David Tingley; Elaine Tseng; Max Tella; Xin Yang; Elizabeth Groeber; Jianhua Liu; Wenlin Li; Christopher J. Schmidt; Rick Steenwyk

2011-01-01

45

A rapid and accurate UPLC/MS/MS method for the simultaneous determination of zolpidem and its main metabolites in biological fluids and its application in a forensic context.  

PubMed

Zolpidem (ZPD) is an imidazopyridine derivative used as a new type of hypnotic and is commonly used in drug-facilitated crimes. A rapid, sensitive, and specific ultra-performance liquid chromatography-tandem mass spectrometry (UPLC/MS/MS) assay method for the simultaneous determination of zolpidem and its main metabolites zolpidem 6-carboxylic acid (ZCA) and zolpidem phenyl-4-carboxylic acid (ZPCA) in biological fluids was developed and validated. Aliquots of 0.1mL blood or urine specimens were used for the analysis, and zolpidem and its metabolites were extracted in a single step using acetonitrile (containing 0.1% formic acid) precipitation. The supernatant was then dried, and 100?L methanol was added. The separation was performed on an Acquity™ UPLC HSS T3 (100mm×2.1mm, 1.8?m) analytical column by API 4000Q ultra-performance liquid chromatography-tandem mass spectrometry. Positive ionisation tandem MS detection in the multiple reaction monitoring (MRM) mode was used. The mobile phases consisted of either acetonitrile or water containing 20mmol/L ammonium acetate and 0.1% formic acid, and the flow rate was 0.5mL/min. The chromatographic separation time was 4min, and calibration curves for human blood were generated over the range of 0.1-300ng/mL for ZPD, 0.1-500ng/mL for ZPCA and 0.1-200ng/mL for ZCA. For urine, the linear range was 0.1-600ng/mL for ZPD and ZPCA, and 0.1-300ng/mL for ZCA. The limit of detection was 0.05ng/mL and the limit of quantitation was 0.1ng/mL for ZPD, ZCA and ZPCA. The linear correlation coefficients were greater than 0.9995. Both the inter-day and intra-day precisions were less than 15%, the recoveries were in the range of 70.0-98.3%, the matrix effects were approximately 79.5-99.0%, and the process efficiency was between 60.7% and 94.4%. This method allowed for the determination of zolpidem and its metabolites in human blood and urine and may be applied to forensic toxicological analyses. PMID:23217317

Shi, Yan; Xiang, Ping; Shen, Baohua; Shen, Min

2012-10-31

46

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

47

Simultaneous measurement of endogenous cortisol, cortisone, dehydroepiandrosterone, and dehydroepiandrosterone sulfate in nails by use of UPLC–MS–MS  

Microsoft Academic Search

Steroid hormone concentrations are mostly determined by using different body fluids as matrices and applying immunoassay techniques.\\u000a However, usability of these approaches may be restricted for several reasons, including ethical barriers to invasive sampling.\\u000a Therefore, we developed an ultra-performance LC–MS–MS method for high-throughput determination of concentrations of cortisol,\\u000a cortisone, dehydroepiandrosterone (DHEA), and DHEA sulfate (DHEAS) in small quantities of human

Mehdi Ben Khelil; Marion Tegethoff; Gunther Meinlschmidt; Carole Jamey; Bertrand Ludes; Jean-Sébastien Raul

48

Simultaneous determination of xylazine, free morphine, codeine, 6-acetylmorphine, cocaine and benzoylecgonine in postmortem blood by UPLC-MS-MS.  

PubMed

Xylazine, a veterinary sedative, has been found as an adulterant of heroin in street drugs in Puerto Rico. It was found in combination with free morphine and 6-acetylmorphine, codeine, cocaine and benzoylecgonine in postmortem cases at the Puerto Rico Institute of Forensic Sciences (PRIFS). Xylazine is not approved for human use because it has been proven harmful. Currently, three separate analyses are required to determine all the aforementioned drugs at the PRIFS's toxicology laboratory. To reduce analysis time consumption, sample volume, run time, sample preparation and cost, a high-throughput ultra-high-pressure liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous quantification of xylazine, free morphine, 6-acetylmorphine, codeine, cocaine and benzoylecgonine in 0.25 mL postmortem blood by protein precipitation, fulfilling confirmation criteria with three transitions for each compound with acceptable relative ion intensities. Linearity was established between 10-1,000 ng/mL. Total run time was 2.5 min. Limit of detection was 1 ng/mL for cocaine and xylazine, 2 ng/mL for 6-acetylmorphine and 10 ng/mL for free morphine, codeine and benzoylecgonine. The intra-day and inter-day precision and accuracy was less than 15.6%. Process efficiencies ranged from 35.9 to 123.4% and recoveries from 59.9 to 110.1%. The developed method was successfully applied to casework. PMID:22582266

Ruiz-Colón, Kazandra; Martínez, María A; Silva-Torres, Luz A; Chavez-Arias, Carlos; Meléndez-Negrón, Margarita; Conte-Miller, María S; Bloom-Oquendo, Joseph

2012-06-01

49

Determination of benzodiazepines in ante-mortem and post-mortem whole blood by solid-supported liquid-liquid extraction and UPLC-MS/MS.  

PubMed

A solid-supported liquid-liquid extraction ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination of benzodiazepines commonly found in Norway, for use in cases with suspected driving impairment and autopsy cases by analysis of human whole blood samples. The following compounds were included: alprazolam, bromazepam, clonazepam, diazepam, flunitrazepam, lorazepam, midazolam, nitrazepam, nordiazepam (metabolite of diazepam), oxazepam and phenazepam. Aliquots of 500 ?L whole blood were added 500 ?L of borate buffer pH 11 and extracted by solid-supported liquid-liquid extraction on ChemElut(®) columns using three times 2.5 mL of methyl tert-butyl ether. Deuterated analogues were used as internal standards (IS) for all analytes, except for midazolam, phenazepam and bromazepam which had no commercially available deuterated analogues at the time the method was developed, and therefore used diazepam-d(5), flunitrazepam-d(7) and nitrazepam-d(5), respectively. The analytes were separated using UPLC with a 2.1×100 mm BEH C(18)-column, 1.7 ?m particle size, and quantified by MS/MS using multiple reaction monitoring (MRM) in positive mode. Two transitions were used for the analytes and one transition for the IS. The run time of the method was 8 min including equilibration time. The concentrations of the benzodiazepines in the method span a broad range varying from the lowest concentration of 0.005 ?M for flunitrazepam to the highest of 20 ?M for oxazepam. The calibration curves of extracted whole blood standards were fitted by second-order calibration curves weighted 1/x, with R(2) values ranging from 0.9981 to 0.9998. The intermediate precision had a CV (%) ranging between 2 and 19%. Recoveries of the analytes were from 71 to 96%. The LLOQs for the analytes varied from 0.0006 to 0.075 ?M and the LODs from 0.005 to 3.0 nM. Matrix effects were studied by post extraction addition and found to be between 95 and 104% when calculated against an internal standard. A comparison with two other LC-MS methods was performed during method validation. Good correlation was seen for all analytes. The method has been running on a routine basis for several years, and has proven to be very robust and reliable with good results for external quality samples. The method also meets the requirements of the legislative limits for driving under the influence of non-alcohol drugs to be introduced in the Norwegian legislative system from 2012. PMID:22119506

Sauve, E N; Langødegård, M; Ekeberg, D; Øiestad, A M L

2011-11-03

50

Development and validation of a sample stabilization strategy and a UPLC-MS/MS method for the simultaneous quantitation of acetylcholine (ACh), histamine (HA), and its metabolites in rat cerebrospinal fluid (CSF).  

PubMed

A UPLC-MS/MS assay was developed and validated for simultaneous quantification of acetylcholine (ACh), histamine (HA), tele-methylhistamine (t-mHA), and tele-methylimidazolacetic acid (t-MIAA) in rat cerebrospinal fluid (CSF). The biological stability of ACh in rat CSF was investigated. Following fit-for-purpose validation, the method was applied to monitor the drug-induced changes in ACh, HA, t-mHA, and t-MIAA in rat CSF following administration of donepezil or prucalopride. The quantitative method utilizes hydrophilic interaction chromatography (HILIC) Core-Shell HPLC column technology and a UPLC system to achieve separation with detection by positive ESI LC-MS/MS. This UPLC-MS/MS method does not require extraction or derivatization, utilizes a stable isotopically labeled internal standard (IS) for each analyte, and allows for rapid throughput with a 4 min run time. Without an acetylcholinesterase (AChE) inhibitor present, ACh was found to have 1.9±0.4 min in vitro half life in rat CSF. Stability studies and processing modification, including the use of AChE inhibitor eserine, extended this half life to more than 60 min. The UPLC-MS/MS method, including stabilization procedure, was validated over a linear concentration range of 0.025-5 ng/mL for ACh and 0.05-10 ng/mL for HA, t-mHA, and t-MIAA. The intra-run precision and accuracy for all analytes were 1.9-12.3% CV and -10.2 to 9.4% RE, respectively, while inter-run precision and accuracy were 4.0-16.0% CV and -5.3 to 13.4% RE, respectively. By using this developed and validated method, donepezil caused increases in ACh levels at 0.5, 1, 2, and 4h post dose as compared to the corresponding vehicle group, while prucalopride produced approximately 1.6- and 3.1-fold increases in the concentrations of ACh and t-mHA at 1h post dose, respectively, compared to the vehicle control. Overall, this methodology enables investigations into the use of CSF ACh and HA as biomarkers in the study of these neurotransmitter systems and related drug discovery efforts. PMID:21684223

Zhang, Yanhua; Tingley, F David; Tseng, Elaine; Tella, Max; Yang, Xin; Groeber, Elizabeth; Liu, Jianhua; Li, Wenlin; Schmidt, Christopher J; Steenwyk, Rick

2011-05-27

51

[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

52

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

2012-11-09

53

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…

Harris, T. D.

1982-01-01

54

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

55

A rapid UPLC-MS/MS method for simultaneous determination of flunitrazepam, 7-aminoflunitrazepam, methadone and EDDP in human, rat and rabbit plasma.  

PubMed

A simple, high-throughput, sensitive LC-ESI-MS/MS method is presented for the simultaneous determination of methadone (MET), flunitrazepam (FNZ) and their major metabolites, EDDP (2-ethilidene-1,5-dimethyl-3,3-diphenylpyrrolidone) and 7-aminoflunitrazepam (7-AFNZ), respectively, in human, rat and rabbit plasma. The isolation of the selected compounds involved a liquid-liquid extraction with ethyl acetate at a basic pH. Good chromatographic separation was achieved on a HSS T3 column (1.8 ?m particle size), with a 3 min gradient elution using a mixture of acetonitrile with 0.1% formic acid (solvent A) and 5mM ammonium acetate (solvent B) as the mobile phase. The tandem mass spectrometric detection was performed in multiple reaction monitoring (MRM) mode with ionization of the analytes in positive mode. The assay was fully validated according to current acceptance criteria for bioanalytical methods validation. It was proved to be linear in the range of 0.5-250 ng/mL, with adequate accuracy and precision over this range. Based on accuracy and CV% values the LOQ and ULOQ values were set at 0.509 ng/mL and 2036 ng/mL for MET, 0.520 ng/mL and 2080 ng/mL for EDDP, 0.524 ng/mL and 2096 ng/mL for FNZ and 0.528 ng/mL and 2114 ng/mL for 7-AFNZ, respectively. The method was tested for potential matrix effects, without observing significant ion suppression. The investigated compounds stability was examined in plasma at room temperature and after three freeze-thaw cycles and in the final extract when maintained at 4 °C in the autosampler. Potential stability issues were observed only for FNZ at room temperature. The method was successfully applied to quantify the selected compounds in human, rat and rabbit plasma samples, after exposure to FNZ or simultaneous exposure to FNZ and MET. PMID:22967607

Kiss, Béla; Bogdan, Catalina; Pop, Anca; Loghin, Felicia

2012-06-29

56

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

2013-03-11

57

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

2013-03-04

58

A new UPLC-MS/MS method for the determination of irinotecan and 7-ethyl-10-hydroxycamptothecin (SN-38) in mice: application to plasma and brain pharmacokinetics.  

PubMed

A sensitive and accurate liquid chromatography method with mass spectrometry detection using MRM in positive ion mode was developed and validated for the simultaneous quantification of irinotecan (CPT-11) and 7-ethyl-10-hydroxycamptothecin (SN-38) in mouse plasma and brain. Camptothecin (CPT) was used as internal standard. A single step protein precipitation was used for plasma sample preparation, and a liquid-liquid extraction was needed for brain sample preparation. The method was validated with respect to selectivity, extraction recovery, linearity, intra- and inter-day precision and accuracy, limit of quantification and stability. Limits of quantification were 5 ng/mL for CPT-11 and SN-38 in plasma samples and 1.25 ng/g in brain. Linear calibration curves were obtained over concentration ranges of 5-5000 ng/mL in plasma and 1.25-1250 ng/g in brain for CPT-11 and SN-38. The intra-day and inter-day variation (relative standard deviation, R.S.D.) found to be less than 15% for both substances in both media. Stability studies showed that plasma carboxylesterase had to be inactivated in order to prevent in vitro conversion of CPT-11 into SN-38. Zinc sulfate (1 M) was used to inactivate the enzyme before sample storage. Brain samples did not require enzyme inactivation. This method was successfully applied to perform brain and plasma pharmacokinetic studies of CPT-11 and SN-38 in mice after intraperitoneal administration. PMID:22551773

Goldwirt, Lauriane; Lemaitre, Florian; Zahr, Noel; Farinotti, Robert; Fernandez, Christine

2012-04-11

59

Determination of free and total warfarin concentrations in plasma using UPLC MS/MS and its application to a patient samples.  

PubMed

Warfarin is routinely monitored by assessing its pharmacologic effects on the international normalized ratio. However, having a patient with INR not responding to increasing warfarin dose mandates a direct measurement of warfarin concentrations (total and free) for better patient clinical management of warfarin therapy. Therefore, a new fully validated specific, precise and accurate ultra-performance liquid chromatography tandem mass spectrometry was developed for the determination of free and total warfarin in human plasma. Free warfarin was measured in plasma filtrate, prepared by ultrafiltration, and sample pretreatment involved protein precipitation with acetonitrile. Linear response (r(2) ?0.99) was observed over the studied range of free and total warfarin, with the lower limit of detection of 0.25 ng/mL. The intra- and inter-day precision (relative standard deviation) values were <10% and the accuracy (relative error) was ?6.6 for free and total warfarin. There was no significant difference (p>0.05) between inter- and intra-day studies for the free and total warfarin, which confirmed the reproducibility of the assay method. The mean extraction efficiency was 88.6-107.2% of free and total warfarin. The assay was sensitive to follow warfarin pharmacokinetics (free and total) in a patient with resistance to warfarin up to 24 h after a daily dose of warfarin. PMID:21374651

Radwan, Mahasen A; Bawazeer, Ghada A; Aloudah, Nouf M; AlQuadeib, Bushra T; Aboul-Enein, Hassan Y

2011-03-04

60

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

2013-07-31

61

Three Highly Sensitive \\  

Microsoft Academic Search

Reliable and fast detection of human choriogonadotropin (hCG) at low concentrations in urine or serum is important in diagnosing early pregnancy, ectopic pregnancy, and missed abortion. In recent years new sensitive \\

Hans H. Thyssen; Ove Schebye

1990-01-01

62

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

63

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

64

High sensitivity SQUID susceptibility measurements  

NASA Astrophysics Data System (ADS)

Scanning superconducting quantum interference device (SQUID) sensors have high sensitivity to magnetic flux ( 10-6?0/?Hz ) and magnetic moment (˜ 100 electron spins) under reasonable scanning conditions. In addition, a single turn field coil co-centered with the SQUID sensing loop provides excitation for simultaneous measurement of low field susceptibility, with sensitivity of ?˜10-6 at a spatial resolution of a few microns. I will present our recent measurements on several systems which exhibit weak susceptometry signals: thin film paramagnetic LaNiO3 that are (hopefully) the precursors to engineered superconducting films; individual magnetotactic bacteria, which are used as MRI contrast agents; and twinned high critical temperature cuprate and pnictide superconducting samples that may experience variations in the superfluid density at the twin boundary.

Kalisky, B.; Kirtley, J. R.; Qian, L. C.; Dwyer, B. L.; Moler, K. A.; Ngai, J.; Segal, Y.; Reiner, J.; Walker, F.; Ahn, C.; Hamilton, A. M.; Rutt, B.; Matin, A. C.; Auslaender, O. M.; Bonn, D. A.; Liang, R.; Hardy, W. N.; Analytis, J. G.; Chu, J.-H.; Fisher, I. R.

2011-03-01

65

High-sensitivity magnetic profiling  

SciTech Connect

A high sensitivity rubidium 87 magnetometer, designed and built by the author, is used at sea to make magnetic profiles over subsurface structures of interest. The Texas AandM University Research Vessel GYRE was used to launch, tow and recover a nonmagnetic fiberglass skiff that carried the magnetometer. To avoid magnetic field disturbances of the GYRE, the skiff with the magnetometer was towed 600 ft behind the ship. Loran C, and sometimes SATNAV, position data were used to determine the ship location. Two recording depth finders using 3.5 kHz and 12 kHz respectively were used to profile the bottom. Time marks were plotted on the magnetic and sonar data in accordance with WWV time signals received on 10 MHz. (15 MHz and 5 MHz were also available if there happened to be poor radio transmission at 10 MHz). Magnetic data were recorded in digital form on a strip chart recorder, using the last two digits of the six digit resonance frequency of the Rb 87 atoms.

Unterberger, R.R.

1983-05-01

66

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

67

High sensitivity radon emanation measurements.  

PubMed

The presented radon detection technique employs miniaturized ultra-low background proportional counters. (222)Rn samples are purified, mixed with a counting gas and filled into a counter using a special glass vacuum line. The absolute sensitivity of the system is estimated to be 40 microBq (20 (222)Rn atoms). For emanation investigations two metal sealed stainless steel vessels and several glass vials are available. Taking into account their blank contributions, measurements at a minimum detectable activity of about 100 microBq can be performed. PMID:19249216

Zuzel, G; Simgen, H

2009-01-25

68

Simultaneous determination of triterpenoid saponins in dog plasma by a validated UPLC-MS/MS and its application to a pharmacokinetic study after administration of total saponin of licorice.  

PubMed

A rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry method was developed for simultaneous determination of eight constituents, uralsaponin C, uralsaponin F, 22?-acetoxyl-glycyrrhizin, 24-hydroxy-licorice-saponin E2, licorice-saponin G2, licorice-saponin E2, glycyrrhizin, and licorice-saponin J2, from total saponin of licorice (TSL) in dog plasma. Ardisiacrispin A was used as the internal standard (IS). The separation was performed on Thermo Syncronic C?? column (100 mm × 2.1 mm, 1.7 ?m) at a flow rate of 0.4 mL min?¹, and acetonitrile/methanol (3:1, v/v)-0.1% 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 negative ionization mode. All calibration curves had good linearity (r>0.991) over the concentration range from 2.03-405 ng mL?¹ to 2.63-2625 ng mL?¹ for all components. The intra- and inter-day precision was within 15% and the accuracy ranged from -14.08% to 13.8%. The method was successfully applied to pharmacokinetic study of eight triterpenoid saponins in dog plasma after oral administration of TSL. PMID:23280090

Tao, Weiwei; Duan, Jinao; Guo, Jianming; Li, Jianping; Tang, Yuping; Liu, Pei; Yang, Nianyun

2012-12-01

69

Development of Highly Sensitive Portable Hydrocarbon Sensors.  

National Technical Information Service (NTIS)

A detailed investigation was performed on developing highly sensitive and portable hydrocarbon sensors using tailored quantum dot materials. These studies focused on using an Ocean Optics fiber optics based spectrometer for monitoring quantum dot arrays t...

M. Carpenter

2009-01-01

70

High Power, High Sensitivity Microwave Calorimeter.  

National Technical Information Service (NTIS)

A microwave calorimeter is disclosed for substantially measuring the total microwave energy in an applied microwave pulse. The microwave calorimeter includes: a housing having a highly reflective interior surface, a microwave device disposed in the housin...

F. M. Mako J. A. Pasour

1989-01-01

71

Highly sensitive detector for submillimeter wavelength range  

NASA Astrophysics Data System (ADS)

A highly sensitive detector of submillimeter wavelength radiation is reported. The detector consists of a semiconductor quantum dot (QD) and a metallic single-electron transistor (SET). The SET detects change in the potential distribution induced by photon absorption within the QD. We have fabricated and studied this detector at wavelengths longer than 200 ?m. High sensitivity, ~10-20 W/Hz in terms of noise equivalent power, is found. Further optimization of the detector design is suggested.

Hashiba, H.; Antonov, V.; Kulik, L.; Komiyama, S.; Stanley, C.

2004-12-01

72

[Determination of sitagliptin phosphate in rat plasma by ultra high performance liquid chromatography-tandem mass spectrometry].  

PubMed

An ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of sitagliptin phosphate in rat plasma was established. The blank rat plasma sample added with sitagliptin phosphate and the internal standard (fluoxetine) standard solution were prepared. Methanol was added in the sample for the deproteinization. Then the sample was vortex-mixed and centrifuged. The clear supernatant was used for the analysis of UPLC-MS/MS. A Thermo Hypersil Gold C18 column (50 mm x 2.1 mm, 1.9 microm) was employed with a guard column of Phenomenex Security Guard C18 column (4 mm x 3.0 mm), and the column temperature was set at 35 degrees C. The gradient elution of acetonitrile and water (containing 0.05% (v/v) formic acid) as mobile phases was performed at a flow rate of 200 microL/min, and a rapid separation was completed in 5 min. The electrospray was operated in the positive ionization mode and the sitagliptin phosphate and fluoxetine were identified by selected reaction monitoring (SRM) mode, and the monitoring ions of them were m/z 408.0 --> 235.0 and m/z 310.0 --> 148.0, respectively, which were used to qualify and quantity the targets by the method of matrix-matched standard solution. The calibration curve showed good linearity within the concentrations of 1 to 1 000 microg/L (r = 0.999 1); the limit of detection was 0.2 microg/L. The mean recoveries were from 85% to 115% at the spiked levels of 5, 50 and 500 microg/L; the relative standard deviations (RSDs) of intra- and inter-day of variation were both less than 15%, which can meet the determination requirements of biological samples. Then the method was initially used for the determination of sitagliptin phosphate in SD rat plasma after the administration of a single intravenous injection dose of sitagliptin phosphate. The method is rapid, sensitive, convenient and reproducible in the determination of sitagliptin phosphate, and can be used for the pharmacokinetics research of sitagliptin phosphate in plasma. PMID:22032156

Tang, Yao; Li, Xiang; Wen, Nie; Sun, Xu; Zhu, Ling; Yu, Min; Li, Zuogang; Li, Bo

2011-06-01

73

High Sensory-Processing Sensitivity at Work  

Microsoft Academic Search

In this study, the construct validity of an instrument for the measurement of sensory-processing sensitivity (SPS), the Highly Sensitive Person Scale (HSPS), was examined. Among the outcomes, first, the results confirm an earlier conclusion of researchers that the HSPS does not measure a one-dimensional construct. Most hypotheses concerning relationships with the personality variables sense of coherence, alienation, self-efficacy, and negative

Arne Evers; Jochem Rasche; Marc J. Schabracq

2008-01-01

74

High-Sensitivity Diode Laser Absorption Spectroscopy  

NASA Astrophysics Data System (ADS)

Recent advances in the vapor phase materials processing have lead to more stringent requirements for diagnostics tools. A new diagnostic tool aimed at meeting some of the new requirements is developed by utilizing high sensitivity diode laser absorption spectroscopy. By suppressing sensitivity limiting etalon fringes while preserving the true absorption signal, the fundamental while noise limited sensitivity of laser absorption spectroscopy is restored. The enhancement of absorption signal to background fringe ratio is obtained by proper control of the operational parameters of a dual modulation scheme dubbed Combined Wavelength and Frequency Modulation Spectroscopy (CWFMS). This dual modulation scheme combines the spectral selectivity of wavelength modulation spectroscopy and the high sensitivity of frequency modulation spectroscopy into one. In addition to the high sensitivity obtained, the scheme provides multiple orders of signals. Any two of those consecutive orders can form a pair of signals for measuring the absorbance and locking the laser frequency simultaneously. One of these two orders has an absolute maximum at the absorption peak while the other is zero crossing and antisymmetric about the absorption peak. The sensitivity of CWFMS has been measured by using several lead-salt diode lasers and an AlGaAs diode laser and white noise limited detection was achieved. CWFMS was applied to two different processing environments namely plasma processing and metalorganic chemical vapor deposition. For plasma processing, characteristics of SF_6 and rm C_2F_6 plasmas were studied. The detection of plasma etching end-point was demonstrated. For metalorganic chemical vapor deposition. The high resolution spectra of methylsilazane during pyrolysis were obtained and analysed to identify a vibrational excited state and methane as a by-product.

Sun, Hoi Cheong (Steve).

75

A high sensitivity, electronically collimated gamma camera  

Microsoft Academic Search

A high sensitivity electronically collimated gamma camera is under development at NOVA. The proposed detector has electronic collimation and will measure the direction of the incident ?-ray directly, hence eliminating the need for a physical collimator. This is accomplished by using the Compton double scatter technique. A feasibility study was successfully completed and prototype fabrication started. The new detector is

T. O. Tumer; Shi Yin; S. Kravis

1996-01-01

76

[Determination of virginiamycin M1, in feeds by ultra high performance liquid chromatography-tandem mass spectrometry].  

PubMed

A comprehensive analytical method based on ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been developed for the determination of virginiamycin M1 in feeds. The sample was extracted twice by ultrasonic extraction with ace-tonitrile-0.2% (v/v) formic acid (8:2, v/v). The chromatographic separation was achieved with a BEH C18 column and acetonitrile-0. 3% (v/v) formic acid (35: 65, v/v) as the mobile phase. The identification and quantification of the analyte were carried out on electrospray ionization MS/MS in a multiple reaction monitoring (MRM) mode. The correlation coefficient (r) of virginiamycin M1 was 0. 999 5 in the linear range of 0. 3 -226. 6 microg/L. The detection limit (S/ N = 3) and quantification limit (S/N = 10) of virginiamycin M1 were 2 microg/kg and 7 microg/kg, respectively. The average spiked recoveries were in the range of 82. 6% to 102. 7% with the relative standard deviations (RSDs) of 0.9% - 10.5%. The results demonstrate that the proposed method is simple, sensitive, repeatable and suitable for the testing of virginiamycin M, in feeds. PMID:22268351

Huang, Yonghui

2011-10-01

77

Electrostatic sensitivity of secondary high explosives  

SciTech Connect

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 and measure baseline data of a few secondary explosives. Although secondary explosives are often considered quite insensitive to an electrostatic discharge, PETN, HMX, and RDX were initiated. Several external elements to the high explosive were found to have an influence on sensitivity. Initiation appeared to be dependent on the nature of the discharge current curve. Those elements recognized as having a significant effect on the results were held constant in this study. These included: distance between discharge plates; sample moisture content; material density; and system resistance, capacitance and inductance. However, no attempt was made in this study to determine the extent to which the high explosive response to electrostatic discharge is affected by these factors since such correlation is not necessary to determine relative sensitivities.

Campos, C.A.

1980-06-01

78

High sensitivity neutron detector for Z  

NASA Astrophysics Data System (ADS)

We have developed, calibrated, and tested a high sensitivity neutron detector that can be operated in the harsh x-ray bremsstrahlung environment that exists in experiments conducted on the 20 MA Z z-pinch facility located at Sandia National Laboratories in Albuquerque, New Mexico. The detector uses a scintillator coupled to a microchannel-plate photomultiplier tube detector and extensive x-ray shielding.

Ruggles, L. E.; Porter, J. L.; Simpson, W. W.; Vargas, M. F.; Zagar, D. M.; Hartke, R.; Buersgens, F.; Symes, D. R.; Ditmire, T.

2004-10-01

79

Rapid and sensitive hormonal profiling of complex plant samples by liquid chromatography coupled to electrospray ionization tandem mass spectrometry  

PubMed Central

Background Plant hormones play a pivotal role in several physiological processes during a plant's life cycle, from germination to senescence, and the determination of endogenous concentrations of hormones is essential to elucidate the role of a particular hormone in any physiological process. Availability of a sensitive and rapid method to quantify multiple classes of hormones simultaneously will greatly facilitate the investigation of signaling networks in controlling specific developmental pathways and physiological responses. Due to the presence of hormones at very low concentrations in plant tissues (10-9 M to 10-6 M) and their different chemistries, the development of a high-throughput and comprehensive method for the determination of hormones is challenging. Results The present work reports a rapid, specific and sensitive method using ultrahigh-performance liquid chromatography coupled to electrospray ionization tandem spectrometry (UPLC/ESI-MS/MS) to analyze quantitatively the major hormones found in plant tissues within six minutes, including auxins, cytokinins, gibberellins, abscisic acid, 1-amino-cyclopropane-1-carboxyic acid (the ethylene precursor), jasmonic acid and salicylic acid. Sample preparation, extraction procedures and UPLC-MS/MS conditions were optimized for the determination of all plant hormones and are summarized in a schematic extraction diagram for the analysis of small amounts of plant material without time-consuming additional steps such as purification, sample drying or re-suspension. Conclusions This new method is applicable to the analysis of dynamic changes in endogenous concentrations of hormones to study plant developmental processes or plant responses to biotic and abiotic stresses in complex tissues. An example is shown in which a hormone profiling is obtained from leaves of plants exposed to salt stress in the aromatic plant, Rosmarinus officinalis.

2011-01-01

80

High-sensitive cardiac troponin T  

PubMed Central

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

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

2013-01-01

81

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

82

High sensitivity nanoparticle detection using optical microcavities.  

PubMed

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 381 from the previously reported 31. 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. PMID:21444782

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

2011-03-28

83

Highly sensitive AMS measurements of 53Mn  

NASA Astrophysics Data System (ADS)

Our AMS system, with the gas-filled detector system GAMS, has been optimized for measurements with 53Mn. A high sensitivity has been achieved. A newly installed cesium sputter ion source yields an improved emittance, and thus a higher mass resolution. By the extraction of the manganese molecule MnF- instead of MnO- we can suppress the isobaric chromium background in the ion source by more than a factor of three. The GAMS system achieves an isobaric suppression factor of about 3 × 108. Measurements on blank samples yielded upper limits for the 53Mn/55Mn ratios of 7 × 10-15.

Poutivtsev, M.; Dillmann, I.; Faestermann, T.; Knie, K.; Korschinek, G.; Lachner, J.; Meier, A.; Rugel, G.; Wallner, A.

2010-04-01

84

The high sensitivity double beta spectrometer TGV  

NASA Astrophysics Data System (ADS)

A high sensitivity double beta spectrometer TGV (Telescope Germanium Vertical) has been developed. It is based on 16 HPGe detectors of volume 1200 × 6 mm3 each in the same cryostat. The TGV spectrometer was proposed for the study of ultrarare nuclear processes (e.g. 2???, 0???, 2?EC/EC). Details of the TGV spectrometer construction are described, the principles of background suppression, the results of Monte Carlo simulations and the results of test background measurements (in Dubna and Modane underground laboratory) are provided.

Briancon, Ch.; Brudanin, V. B.; Egorov, V. G.; Janout, Z.; Koní?ek, J.; Kovalík, A.; Kovalenko, V. E.; Kubašta, J.; Pospíšil, S.; Revenko, A. V.; Rukhadze, N. I.; Salamatin, A. V.; Sandukovsky, V. G.; Štekl, I.; Timkin, V. V.; Tsupko-Sitnikov, V. V.; Vorobel, V.; Vylov, Ts.

1996-02-01

85

High Sensitivity VLBI Science with Arecibo  

NASA Astrophysics Data System (ADS)

Modern VLBI instrumentation bears little resemblence to the systems that were in use just 5 years ago. By making use of industry driven trends, VLBI has moved from recording on magnetic tape to hard disk drive systems, and has replaced analog filterbanks with digital signal processing on FPGAs. The results are significantly increased recording bandwidths at a small fraction of the cost of previous VLBI systems. When this instrumentation is deployed on the largest radio telescopes, thermal noise levels down to 1 micro Jy/beam can be achieved. The collecting area of Arecibo, in particular, lowers detection thresholds to the point where a range of high sensitivity science projects can be addressed. Among these are studies of Ultra Luminous Infrared Galaxies (ULIGs), central images of Gravitational Lens systems, late time imaging of GRB afterglow structure, and pulsar astrometry and proper motion studies. This talk will briefly touch on enabling technologies and then focus on the ongoing and potential research enabled with Arecibo-anchored VLBI arrays. The Ultra High Sensitivity VLBI program at MIT Haystack Observatory is funded through a grant from the NSF AST division.

Doeleman, Sheperd

2007-12-01

86

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

87

Highly sensitive microwave temperature-jump apparatus.  

PubMed

A temperature-jump apparatus with repetitive microwave heating and spectrophotometric detection is described. Temperature jumps of 1.5 degrees C are achieved in a flow microcell within 1.5 mus (two shorter heating times of 0.5 and 0.25 mus are also available) at a repetition rate up to 50 Hz. On-line accumulation of the relaxation signals is performed with a PDP 11 processor, leading to very short recording times (more than 1000 signals accumulated in less than 50 s) and to a sensitivity better than 10(-4) optical density (OD) units. Nonlinear identification treatment permits processing the summed signal even when it is strongly blurred by noise. To demonstrate the capabilities of our apparatus, highly shifted fast prototropic equilibria in aqueous solutions of pyrimidine base have been studied. PMID:18699338

Aubard, J; Nozeran, J M; Levoir, P; Meyer, J J; Dubois, J E

1979-01-01

88

High sensitivity amplifier/discriminator for PWC's  

SciTech Connect

The facility support group at Fermilab is designing and building a general purpose beam chamber for use in several locations at the laboratory. This pwc has 128 wires per plane spaced 1 mm apart. An initial production of 25 signal planes is anticipated. In proportional chambers, the size of the signal depends exponentially on the charge stored per unit of length along the anode wire. As the wire spacing decreases, the capacitance per unit length decreases, thereby requiring increased applied voltage to restore the necessary charge per unit length. In practical terms, this phenomenon is responsible for difficulties in constructing chambers with less than 2 mm wire spacing. 1 mm chambers, therefore, are frequently operated very near to their breakdown point and/or a high gain gas containing organic compounds such as magic gas is used. This argon/iso-butane mixture has three drawbacks: it is explosive when exposed to the air, it leaves a residue on the wires after extended use and is costly. An amplifier with higher sensitivity would reduce the problems associated with operating chambers with small wire spacings and allow them to be run a safe margin below their breakdown voltage even with an inorganic gas mixture such as argon/CO2, this eliminating the need to use magic gas. Described here is a low cost amplifier with a usable threshold of less than 0.5 ..mu..A. Data on the performance of this amplifier/discriminator in operation on a prototype beam chamber are given. This data shows the advantages of the high sensitivity of this design.

Hansen, S.

1983-01-01

89

Highly sensitive silicon microreactor for catalyst testing  

SciTech Connect

A novel microfabricated chemical reactor for highly sensitive measurements of catalytic activity and surface kinetics is presented. The reactor is fabricated in a silicon chip and is intended for gas-phase reactions at pressures ranging from 0.1 to 5.0 bar. A high sensitivity is obtained by directing the entire gas flow through the catalyst bed to a mass spectrometer, thus ensuring that nearly all reaction products are present in the analyzed gas flow. Although the device can be employed for testing a wide range of catalysts, the primary aim of the design is to allow characterization of model catalysts which can only be obtained in small quantities. Such measurements are of significant fundamental interest but are challenging because of the low surface areas involved. The relationship between the reaction zone gas flow and the pressure in the reaction zone is investigated experimentally. A corresponding theoretical model is presented, and the gas flow through an on-chip flow-limiting capillary is predicted to be in the intermediate regime. The experimental data for the gas flow are found to be in good agreement with the theoretical model. At typical experimental conditions, the total gas flow through the reaction zone is around 3x10{sup 14} molecules s{sup -1}, corresponding to a gas residence time in the reaction zone of about 11 s. To demonstrate the operation of the microreactor, CO oxidation on low-area platinum thin film circles is employed as a test reaction. Using temperature ramping, it is found that platinum catalysts with areas as small as 15 {mu}m{sup 2} are conveniently characterized with the device.

Henriksen, Toke R.; Hansen, Ole [Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech Building 345 East, DK-2800 Kgs. Lyngby (Denmark); Department of Physics, Danish National Research Foundation's Center for Individual Nanoparticle Functionality (CINF), Technical University of Denmark, Building 312, DK-2800 Kgs. Lyngby (Denmark); Olsen, Jakob L.; Vesborg, Peter; Chorkendorff, Ib [Department of Physics, Danish National Research Foundation's Center for Individual Nanoparticle Functionality (CINF), Technical University of Denmark, Building 312, DK-2800 Kgs. Lyngby (Denmark)

2009-12-15

90

Highly sensitive silicon microreactor for catalyst testing  

NASA Astrophysics Data System (ADS)

A novel microfabricated chemical reactor for highly sensitive measurements of catalytic activity and surface kinetics is presented. The reactor is fabricated in a silicon chip and is intended for gas-phase reactions at pressures ranging from 0.1 to 5.0 bar. A high sensitivity is obtained by directing the entire gas flow through the catalyst bed to a mass spectrometer, thus ensuring that nearly all reaction products are present in the analyzed gas flow. Although the device can be employed for testing a wide range of catalysts, the primary aim of the design is to allow characterization of model catalysts which can only be obtained in small quantities. Such measurements are of significant fundamental interest but are challenging because of the low surface areas involved. The relationship between the reaction zone gas flow and the pressure in the reaction zone is investigated experimentally. A corresponding theoretical model is presented, and the gas flow through an on-chip flow-limiting capillary is predicted to be in the intermediate regime. The experimental data for the gas flow are found to be in good agreement with the theoretical model. At typical experimental conditions, the total gas flow through the reaction zone is around 3×1014 molecules s-1, corresponding to a gas residence time in the reaction zone of about 11 s. To demonstrate the operation of the microreactor, CO oxidation on low-area platinum thin film circles is employed as a test reaction. Using temperature ramping, it is found that platinum catalysts with areas as small as 15 ?m2 are conveniently characterized with the device.

Henriksen, Toke R.; Olsen, Jakob L.; Vesborg, Peter; Chorkendorff, Ib; Hansen, Ole

2009-12-01

91

Transportable high sensitivity small sample radiometric calorimeter  

SciTech Connect

A new small-sample, high-sensitivity transportable radiometric calorimeter, which can be operated in different modes, contains an electrical calibration method, and can be used to develop secondary standards, will be described in this presentation. The data taken from preliminary tests will be presented to indicate the precision and accuracy of the instrument. The calorimeter and temperature-controlled bath, at present, require only a 30-in. by 20-in. tabletop area. The calorimeter is operated from a laptop computer system using unique measurement module capable of monitoring all necessary calorimeter signals. The calorimeter can be operated in the normal calorimeter equilibration mode, as a comparison instrument, using twin chambers and an external electrical calibration method. The sample chamber is 0.75 in (1.9 cm) in diameter by 2.5 in. (6.35 cm) long. This size will accommodate most {sup 238}Pu heat standards manufactured in the past. The power range runs from 0.001 W to <20 W. The high end is only limited by sample size.

Wetzel, J.R.; Biddle, R.S.; Cordova, B.S.; Sampson, T.E.; Dye, H.R.; McDow, J.G.

1998-12-31

92

Demonstration of high sensitivity laser ranging system  

NASA Astrophysics Data System (ADS)

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

93

A high sensitivity electromagnetic field sensor using resonance  

Microsoft Academic Search

High sensitivity electromagnetic field distribution mapping is useful for analyzing intra-system EMC issues. We have developed a high sensitivity electromagnetic sensor for this mapping. The sensor uses the resonance of an inductive loop and a chip capacitor. The sensitivity of a system using this sensor is improved by about 20 dB compared to a conventional one. This paper studies the

Hiroshi Tsutagaya; Satoshi Kazama

2008-01-01

94

High displacement sensitivity in asymmetric plasmonic nanostructures.  

PubMed

The strong couplings between two asymmetric plasmonic nanostructures can lead to ultra-sensitive optical responses when their separation changes. We employ electromagnetic numerical simulations to study the displacement sensitivity of two kinds of plasmonic systems: (1) a split-ring resonator and a metal rod; (2) two metal rods of asymmetric lengths. Structural asymmetry makes antiparallel current interactions possible and greatly enhances the sensitivity to 5%/nm for normalized frequency changes and 29%/nm for normalized transmittance changes. These are the highest displacement sensitivity among all physical systems investigated so far. In addition, we also find that these systems display a universal scaling curve independent of their shapes or dimensions. These asymmetric plasmonic nanostructures will open widespread applications from strain mapping, surface wave or heat wave imaging, optomechanical sensing, to environmental detections. PMID:20721229

Tseng, Hsuan-Chi; Chang, Chih-Wei

2010-08-16

95

A highly chilling-sensitive angiosperm  

Microsoft Academic Search

Young expanding leaves of Episcia were irreversibly injured after as little as 15 seconds of chilling at 0°C. Chilling damage\\u000a to the leaves was measured by the decrease of induced chlorophyll fluorescence in vivo. Chilling tolerance increased with\\u000a leaf age, but even the oldest non-senescing leaves were considerably more sensitive than leaves of chilling intolerant plants\\u000a such as bean, cucumber

Robert M. Smillie

1984-01-01

96

Highly sensitive thermal actuators for temperature sensing  

NASA Astrophysics Data System (ADS)

A thermal actuator based on two symmetrical V-shaped beam stacks (also called chevron-type) is presented. Each beam stack consists of 6 beams in parallel. The stacks are coupled facing each other and are slightly shifted along the mirror axis. Both stacks are connected to a lever beam. Due to the thermal expansion of the material, the tip of the lever moves up and downwards perpendicular to the mirror axis. The device is built up of galvanic deposited nickel. Finite element simulations were carried out for design considerations prior to the manufacturing of the device. The simulations were used to optimize the design regarding to the sensitivity and the maximum mechanical stress to be expected. The stress level needs to be lower than the yield strength of the material, to prevent plastic deformation and, therefore, irreversible tip defections. This also limits the overall sensitivity of the design. First results of the device with 400 µm long bent beams show a linear behavior and a sensitivity of 0.5 ?m/K and expectable forces of 66 ?N/K in a temperature range of -30°C up to +40°C.

Steiner, H.; Hortschitz, W.; Stifter, M.; Keplinger, F.; Sauter, T.

2013-05-01

97

High detection efficiency neutron sensitive microchannel plate  

NASA Astrophysics Data System (ADS)

Direct addition of neutron-absorbing atoms into MCP glass, such as 10B and 155,157Gd, without changing the remainder of MCP fabrication process, can make MCP sensitive to neutrons. Since the much larger cross section of 157Gd, the MCP doped with natGd2O3 is more efficient than one doped with enriched 10B2O3, theoretical indicates that the detection efficiency of a MCP doped with 3 mole% of natGd2O3 is equivalent even superior to a MCP doped with 20 mole% of 10B2O3. In this paper a 50 mm diameter rimless format 10 ?m pore diameter MCP doped with 3 mole% natGd2O3 was fabricated, but the MCP glass doped with 20 mol% of natB2O3 failed to pass through the corrosive chemical processing necessary in MCPs manufacture. A primary experimental tests proved the MCP doped with 3 mole% natGd2O3 is capable of imaging thermal neutrons with 35% detection efficiency. A potential of enhancement on detection efficiency should be achieved for a optimized geometry MCP with an appropriate selection between bias angle, open area ratio and length to diameter ratio.

Pan, J.; Yang, Y.; Tian, Y.; Zeng, M.; Deng, T.; Xu, W.; Han, X.; Sun, S.; Lv, J.

2013-01-01

98

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

99

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

100

High Sensitivity Millimeter and Infrared Radiometric Receiver.  

National Technical Information Service (NTIS)

An MMIC (millimeter-microwave-integrated-circuit) mixer has been developed for use at Ka-band. This mixer incorporates high quality beam leaded GaAs Schottky diodes, bonded to a thin low-dielectric constant substrate, which contains the mixer hybrid and a...

A. J. Kelly H. C. Okean F. R. Arams

1974-01-01

101

Novel CCD structures of high sensitivity  

NASA Astrophysics Data System (ADS)

A new class of charge-coupled devices called junction virtual phase (JVP) CCD's is described. JVP CCDs have very high photosensitivity because their pixels are designed without any metal or polysilicon gates. A new principle of buried channel modulation through a narrow depleted layer is used. This principle is realized in a few JVP structures. Two dimensional simulation of these structures are presented.

Kostukov, Evgeni V.; Pugachev, Andre A.; Shilin, Victor A.; Veto, Alexander V.

1996-04-01

102

Insufficient forcing uncertainty underestimates the risk of high climate sensitivity  

NASA Astrophysics Data System (ADS)

Uncertainty in climate sensitivity is a fundamental problem for projections of the future climate. Equilibrium climate sensitivity is defined as the asymptotic response of global-mean surface air temperature to a doubling of the atmospheric CO2 concentration from the preindustrial level (?280 ppm). In spite of various efforts to estimate its value, climate sensitivity is still not well constrained. Here we show that the probability of high climate sensitivity is higher than previously thought because uncertainty in historical radiative forcing has not been sufficiently considered. The greater the uncertainty that is considered for radiative forcing, the more difficult it is to rule out high climate sensitivity, although low climate sensitivity (<2°C) remains unlikely. We call for further research on how best to represent forcing uncertainty.

Tanaka, Katsumasa; Raddatz, Thomas; O'Neill, Brian C.; Reick, Christian H.

2009-08-01

103

A design of highly sensitive GMI sensor  

Microsoft Academic Search

Employing amplitude-modulation technique, we have optimized the giant magnetoimpedance (GMI) sensor. Our approach was to optimize the sensor structure so as to obtain a high signal-to-noise ratio by using finite element analysis. The optimum size of sensor strip is as follows: a thickness of 4.3?m, a strip width of 20–30?m, a length of several mm. The meander sensor element [CoNbZr

S. Yabukami; H. Mawatari; N. Horikoshi; Y. Murayama; T. Ozawa; K. Ishiyama; K. I. Arai

2005-01-01

104

Triggers for a high sensitivity charm experiment  

NASA Astrophysics Data System (ADS)

Any future charm experiment clearly should implement an E(sub T) trigger and a (mu) trigger. In order to reach the 10(exp 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, David C.

1994-07-01

105

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

106

Highly sensitive taste sensor with a new differential LAPS method  

Microsoft Academic Search

A new differential measurement method for a LAPS (light-addressable potentiometric sensor) has been developed and applied to fabricate an integrated taste sensor with artificial lipid membranes as the ion-sensitive material. The differential measurement procedure is based on a time-sharing technique, which makes it possible to achieve a very sensitive and highly stabilized response due to the noise-compensation effect. Sensitivity enhancement

Y. Sasaki; Y. Kanai; H. Uchida; T. Katsube

1995-01-01

107

calibration Improves Methylation sensitive High resolution Melting Analysis  

Microsoft Academic Search

Methylation-sensitive (MS) Hi-Res Melting is a sensitive detection method that requires no post-PCR sample manipulation. Analysis is fast and simple and achieved by comparing melting temperature (Tm) and melting curve shape. Multiple CpGs can be simultaneously analyzed. This technique is sensitive enough to show a single methylation event within a group of multiple CpGs. High discrimination is possible because of

C. N. Gundry; M. Wall; J. T. McKinney; C. Hough; L. Cutler; J. D. Phillips; M. K. Yu

2008-01-01

108

Highly Sensitive VGA FEA-HARP Image Sensor  

Microsoft Academic Search

A 640×480 pixel image sensor consisting of 20×20-µm pixels, which consisted of an integrated field emitter array equipped with an active drive circuit and a highly sensitive avalanche-mode photoconductive target was fabricated and tested to investigate the feasibility of a high-resolution sensor with a large number of smaller pixels. Our experimental results revealed that the prototype obtained both high sensitivity

N. Egami; M. Nanba; Y. Honda; Y. Hirano; K. Miyakawa; Y. Ookawa; T. Watabe; S. Okazaki; K. Miya; K. Nakamura; T. Niiyama; M. Taniguchi; S. Itoh; A. Kobayashi

109

Notch sensitivity of high strenght steels  

Microsoft Academic Search

A steel with 0.64-0.66~ 0.78-0.85 Mn, 0.24-0.28 Si and 0.22-0.23 Mo, as well as other high-strength steels were tested. The test results on Soviet steels displayed in Fig. 3 agree with the data in [1,2]. The fatigue limit was determined on rotating 7.5 mm dia specimens with a 0.75 mm notch radius. Fig. 4 shows that the fatigue limit of

M. P. Markovets

1960-01-01

110

Development of a high sensitivity DFB fibre laser hydrophone  

Microsoft Academic Search

Over the last three decades, extensive research has been carried out towards the development of fibre optic hydrophones. The initial designs focused on strain sensitivity enhancements through coatings and coiling long fibres on compliant mandrels. With the advent of fibre Bragg gratings and fibre lasers with ultra high sensitivity to strain, the interest has shifted towards employing these technologies in

Unnikrishnan Kuttan Chandrika; Venugopalan Pallayil; Chen Zhihao; Ng Jun Hong

2011-01-01

111

High Sensitivity Pressure Sensors Utilizing Advanced Polymer Coatings.  

National Technical Information Service (NTIS)

We report a high sensitivity pressure sensor utilizing optical fibers coated with novel polymers. Pressure sensitivity of 5 pico-m/psi for the fiber Bragg grating based and 155 dB radian/micro-Pa for interferometric sensor is reported.

A. Dandridge A. B. Tveten C. C. Chang G. A. Johnson S. T. Vohra

1999-01-01

112

High Sensitivity Detection of Bacterial Endospores via TB Photoluminescence Enhancement.  

National Technical Information Service (NTIS)

Detecting bacterial endospores is a critical challenge to bioanalytical chemistry, since a number of serious diseases and health problems are caused by members of the sporeforming genera Bacillus and Clostridium. We have developed a highly sensitive metho...

N. F. Fell P. M. Pellegrino J. B. Gillespie

2002-01-01

113

Highly sensitive gas sensor based on integrated titania nanosponge arrays  

NASA Astrophysics Data System (ADS)

Highly sensitive gas sensors were fabricated using nanostructured titania pad arrays. Nanostructured titania (NST) formed is sponge-like consisting of interconnected nanoscale wires and walls, which are made up of anatase nanocrystals. Electrical characterization indicates that contacts were ohmic and NST was highly sensitive to O2. Variations of hundreds of oxygen molecules over a 20 ?m NST square pad sensing element were detected at 250 °C. The NST-based sensor operates at lower temperatures, has fast response time, and superior sensitivity relative to oxygen sensors based on porous undoped titania reported in the literature.

Zuruzi, A. S.; Kolmakov, A.; MacDonald, N. C.; Moskovits, M.

2006-03-01

114

Simultaneous determination of DL-lactic acid and DL-3-hydroxybutyric acid enantiomers in saliva of diabetes mellitus patients by high-throughput LC-ESI-MS/MS.  

PubMed

A simultaneous determination method for the enantiomers of chiral carboxylic acids by the combination of ultraperformance liquid chromatography and mass spectrometry (UPLC-MS/MS) has been developed. (S)(+)-1-(2-Pyrrolidinylmethyl)-pyrrolidine (S-PMP) was used as the derivatization reagent for the high-throughput determination of biological chiral carboxylic acids, i.e., lactic acid (LA) and 3-hydroxybutyric acid (HA). The S-PMP efficiently reacted with the carboxylic acids under mild conditions at room temperature in the presence of 2,2'-dipyridyl disulfide and triphenylphosphine. The resulting S-PMP derivatives were highly responsive in the electrospray ionization (ESI)-MS operating in the positive-ion mode and gave characteristic product ions during the MS/MS, which enabled the sensitive detection using selected reaction monitoring. The derivatization was effective for the enantiomeric separation of the chiral carboxylic acids, and the resolution values of DL-LA and DL-HA were 4.91 and 9.37, respectively. Furthermore, a rapid separation of the derivatives of DL-LA and DL-HA within 7 min was performed using the UPLC system. The limits of detection on the column were in the low femtogram range (5-12 fg). The proposed procedure was successfully applied for the determination of the D- and L-isomers of LA and HA in the saliva of diabetes mellitus (DM) patients and healthy volunteers. The D-LA in DM patients was clearly higher than that in normal subjects. The derivatization followed by UPLC-ESI-MS/MS enabled the enantiomeric separation and detection of trace amounts of LA and HA in human saliva with a simple pretreatment and small sample volume. PMID:22895741

Tsutsui, Haruhito; Mochizuki, Toshiki; Maeda, Toshio; Noge, Ichiro; Kitagawa, Yutaka; Min, Jun Zhe; Todoroki, Kenichiro; Inoue, Koichi; Toyo'oka, Toshimasa

2012-08-16

115

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

Microsoft Academic Search

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

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

2011-01-01

116

Applications of high resolution high sensitivity observations of the CMB  

NASA Astrophysics Data System (ADS)

With WMAP putting the phenomenological standard model of cosmology on a strong footing, one can look forward to mining the cosmic microwave background (CMB) for fundamental physics with higher sensitivity and on smaller scales. Future CMB observations have the potential to measure absolute neutrino masses, test for cosmic acceleration independent of supernova Ia observations, probe for the presence of dark energy at z?2, illuminate the end of the dark ages, measure the scale-dependence of the primordial power spectrum and detect gravitational waves generated by inflation.

Kaplinghat, Manoj

2003-12-01

117

Sensitive High Frequency AC Susceptometry in Magnetic Nanoparticle Applications  

Microsoft Academic Search

We report on the development of a sensitive high frequency susceptometer capable of measuring in the frequency range from 25 kHz up to 10 MHz with a volume susceptibility sensitivity of 3.5×l0-5 at 100 kHz corresponding to about 0.3% of the measured AC susceptibility. In combination with the previous reported DynoMag system capable of measuring dynamic magnetic properties in the

Fredrik Ahrentorp; Andrea P. Astalan; Christian Jonasson; Jakob Blomgren; Bin Qi; Olin Thompson Mefford; Minhao Yan; Je´re´mie Courtois; Jean-François Berret; Olivier Sandre; Silvio Dutz; Robert Müller; Christer Johansson

2010-01-01

118

High-Sensitivity Accelerometer Using Multilayer Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

A high sensitivity accelerometer using multilayer piezoelectric ceramics including internal electrodes has been developed. The sensitivity of this accelerometer is about 900 pC/G at the frequency range from 0.01 to 10 Hz. Because the circuit was structed to cancel pyroelectric voltages, the output voltage changes of this accelerometer were decreased to 1/10 compared with the case of a noncanceling circuit.

Ohtsuki, Yasunori; Fuda, Yoshiaki; Yoshida, Tetsuo

1993-09-01

119

Passive imaging with a highly-sensitive infrared phototransistor  

Microsoft Academic Search

A scanning confocal long-wavelength infrared (LWIR) microscope has been developed by using a highly-sensitive, novel LWIR detector (charge-sensitive infrared phototransistor) for wavelengths -14.7 mum. Samples and Ge objective lens are placed at room temperature, while other optics including a confocal pinhole, Ge relay lenses, and the detector are cooled down to 4.2 K. Passive LWIR imaging has been achieved with

Y. Kajihara; S. Komiyama; P. Nickels; T. Ueda

2009-01-01

120

[Determination of caftaric acid, p-coutaric acid and fertaric acid in grape juice, peel and seeds by ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry].  

PubMed

An ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry (UPLC-MS/MS) method was developed for the determination of hydroxycinnamoyltartaric esters, such as caftaric acid, p-coutaric acid and fertaric acid in grape juice, peel and seed. The target analytes were separated on a Waters UPLC HSS T3 column (150 mm x 2.1 mm, 1.7 microm) at 35 degrees C with gradient elution at a flow rate of 0.3 mL/min. The grape juice was freeze-centrifuged, the supernatant was diluted with 20% methanol. The grape peel and grape seed samples were extracted with 80% ethanol. The extract was cleaned-up on-line with the analytical column by valve switching technology. The mobile phases were water-acetonitrile (both containing 0.1% formic acid). The identification and quantification were achieved by MS/MS in multiple reaction monitoring (MRM) mode via negative electrospray ionization. As lack of commercial standards, p-coutaric acid and fertaric acid were quantified by caftaric acid equivalent. The developed method showed a good linearity over the range of 25-2 000 microg/L with good correlation coefficient (r2 = 0.998 9). The limit of detection was 0.25 microg/L, and the limit of quantification was 25 microg/L. The average recoveries of caftaric acid were between 97.7%-99.5% and the precisions were within 2.5% at the spiked levels of 250, 750 and 1 200 microg/L. The working solutions were stable for 74 h at room temperature. The results showed that there are significant differences of hydroxycinnamoyltartaric esters distribution in grape juice, peel and seeds. Therefore, this method, owing to its simplicity, rapidity, good recovery, high sensitivity and accuracy, can be used for the analysis of caftaric acid, p-coutaric acid and fertaric acid in grape juice, peel and seeds. PMID:23697175

Zhang, Lingyi; Wang, Zhicong; Zhang, Weibing

2013-02-01

121

Taste reactivity in high-alcohol-sensitive and low-alcohol-sensitive rats  

Microsoft Academic Search

High, low, and control alcohol-sensitive (HAS, LAS, CAS, respectively) rats were tested for their perception of the taste of alcohol using the taste reactivity test. Reactivity tests with a single concentration of sucrose and quinine were also done. After initial taste reactivity, all rats were tested for alcohol consumption in a standard two-bottle test (water in the second bottle). Postconsumption

Stephen W. Kiefer; Nancy E. Badia-Elder

1997-01-01

122

Instrumentation for high-efficiency, high-sensitivity actinide analysis  

SciTech Connect

This is the final report of a 3-year project. We have developed a high-efficiency thermal ionization source that provides one to two orders of magnitude improvement in sample utilization efficiency in comparison with the traditional filament-type ion source currently used in thermal ionization mass spectrometry. This improved sample utilization efficiency results in a proportional increase in sample throughput and proportional decrease in analysis time. Coupling this source with a quadrupole mass spectrometer results in an instrument system for high-efficiency actinide analysis and other applications. In addition to its high efficiency, the sample used in this source can be much smaller than that in previous tube-type sources. The compact structure of the cavity makes it more applicable to any type of mass spectrometer and the whole instrument is small and transportable.

Olivares, J.; Chamberlin, E.; Murrell, M.; Kahr, M.; Duan, Y.

1996-04-01

123

Sensitive High Frequency AC Susceptometry in Magnetic Nanoparticle Applications  

NASA Astrophysics Data System (ADS)

We report on the development of a sensitive high frequency susceptometer capable of measuring in the frequency range from 25 kHz up to 10 MHz with a volume susceptibility sensitivity of 3.5×l0-5 at 100 kHz corresponding to about 0.3% of the measured AC susceptibility. In combination with the previous reported DynoMag system capable of measuring dynamic magnetic properties in the range from 1 Hz to 200 kHz we are thus able to measure dynamic magnetic properties between 1 Hz to 10 MHz with high magnetic sensitivity. We will show AC susceptometry applications and results within the fields of magnetic hyperthermia and dynamic magnetic characterization of magnetic nanoparticle system with different particle sizes and magnetic properties.

Ahrentorp, Fredrik; Astalan, Andrea P.; Jonasson, Christian; Blomgren, Jakob; Qi, Bin; Mefford, Olin Thompson; Yan, Minhao; Courtois, Jérémie; Berret, Jean-François; Fresnais, Jérôme; Sandre, Olivier; Dutz, Silvio; Müller, Robert; Johansson, Christer

2010-12-01

124

Microstructure-sensitive modeling of high cycle fatigue  

Microsoft Academic Search

Strategies are described for microstructure-sensitive computational methods for estimating variability of high cycle fatigue (HCF) crack formation and early growth in metallic polycrystals to support design of fatigue resistant alloys. We outline a philosophy of employing computational simulation to establish relations between remote loading conditions and microstructure-scale slip behavior in terms of Fatigue Indicator Parameters (FIPs) as a function of

Craig Przybyla; Rajesh Prasannavenkatesan; Nima Salajegheh; David L. McDowell

2010-01-01

125

The comprehensive midtrimester test: High-sensitivity down syndrome test  

Microsoft Academic Search

Objective: The purpose of this study was to develop a highly sensitive algorithm for midtrimester Down syndrome detection. Study design: Urine (hyperglycosylated human chorionic gonadotropin, ?-core fragment of human chorionic gonadotropin), serum (?-fetoprotein, human chorionic gonadotropin and unconjugated estriol [uE3]), and ultrasound biometry (nuchal thickness, humerus length, the presence of gross ultrasonographic anomalies), and maternal age were measured at genetic

Ray Bahado-Singh; Shohreh Shahabi; Mehmet Karaca; Maurice J. Mahoney; Laurence Cole; Utku A. Oz

2002-01-01

126

Invention of highly sensitive HARP camera tube and its application  

Microsoft Academic Search

In 1985, I found that when an amorphous selenium (a-Se) photoconductive target for camera tubes is operated in a strong electric field of about 108 V\\/m, continuous and stable avalanche multiplication takes place, allowing high sensitivity to be obtained with little picture degradation. Based on this discovery, we went on to develop a new kind of camera tube called HARP

K. Tanioka

2003-01-01

127

Transimpedance Amplifier for High Sensitivity Current Measurements on Nanodevices  

Microsoft Academic Search

The paper presents a very high sensitivity transimpedance amplifier in standard CMOS 0.35 mum technology suited for sensing current signals from molecular and nanodevices systems. The circuit, based on an integrator followed by a differentiator configuration, features i) a low-noise time-continuous feedback loop to cope with possible standing currents from the device under test as high as few tens of

Giorgio Ferrari; Fabio Gozzini; Alessandro Molari; Marco Sampietro

2009-01-01

128

New Experimental High Sensitivity Magnetic Observatory Installation In Mexico  

NASA Astrophysics Data System (ADS)

Newly installed magnetic observatory consists of Potassium dIdD and Potassium Supergradiometer. It is a byproduct of experiments in Earthquake studies that have started in 2005 after installation of Potassium Supergradiometer in Oaxaca Province of Mexico. Supergrad's sensitivity of about 50fT (0.05pT) is sufficient for a short base gradiometric studies of Earthquakes. One of the obstacles of this installation is a minute difference in magnetic field direction at the three Supergrad sensors. This difference is causing invasion of diurnal changes of magnetic field into gradients between the sensors of the order of 10-30pT. High sensitivity Potassium dIdD is needed to correct for this phenomenon. The dIdD was installed May 2008 and the first results are expected shortly thereafter. Potassium dIdD will measure components of magnetic field with pT sensitivity.

Lopez Garibay, F.; Hrvoic, I.; Wilson, M.; Cabral, E.; Cifuentes, G.; Hernandez, E.

2008-12-01

129

High-sensitivity microfluidic calorimeters for biological and chemical applications  

PubMed Central

High-sensitivity microfluidic calorimeters raise the prospect of achieving high-throughput biochemical measurements with minimal sample consumption. However, it has been challenging to realize microchip-based calorimeters possessing both high sensitivity and precise sample-manipulation capabilities. Here, we report chip-based microfluidic calorimeters capable of characterizing the heat of reaction of 3.5-nL samples with 4.2-nW resolution. Our approach, based on a combination of hard- and soft-polymer microfluidics, provides both exceptional thermal response and the physical strength necessary to construct high-sensitivity calorimeters that can be scaled to automated, highly multiplexed array architectures. Polydimethylsiloxane microfluidic valves and pumps are interfaced to parylene channels and reaction chambers to automate the injection of analyte at 1 nL and below. We attained excellent thermal resolution via on-chip vacuum encapsulation, which provides unprecedented thermal isolation of the minute microfluidic reaction chambers. We demonstrate performance of these calorimeters by resolving measurements of the heat of reaction of urea hydrolysis and the enthalpy of mixing of water with methanol. The device structure can be adapted easily to enable a wide variety of other standard calorimeter operations; one example, a flow calorimeter, is described.

Lee, Wonhee; Fon, Warren; Axelrod, Blake W.; Roukes, Michael L.

2009-01-01

130

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

131

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

132

High-sensitivity diamond magnetometer with nanoscale resolution  

NASA Astrophysics Data System (ADS)

We will discuss our recent work on using isolated electronic spins in the solid-state as sensitive magnetic sensors [1,2]. This novel approach to magnetometry is enabled by the good coherence properties of electronic qubits, such as the spins associated with Nitrogen-Vacancy (NV) centers in diamond, as well as by advanced techniques for their coherent control. The key feature of this solid-state magnetometer is the possibility to confine the sensing spins into a crystal of nanometer size that can be brought extremely close to the magnetic field source, thus achieving high spatial resolution. Our first experiments demonstrate that the resulting magnetic sensor provides an unprecedented combination of ultra-high sensitivity and spatial resolution. The ultimate sensitivity limit is set by the interaction of the spin sensor with its environment and in particular the nuclear and electronic spin bath. As an outlook, we will discuss how engineering, controlling or harnessing the environment can lead to better sensitivity, even beyond the standard quantum limit. Finally, we will outline several exciting applications of the novel magnetic sensors in areas ranging from bio- and materials science to fundamental physics and single electronic and nuclear spin detection. [4pt] [1] J. M. Taylor, et al. Nature Phys. 4, 810-816 (2008). [0pt] [2] J. R. Maze, et al. Nature 455, 644 - 647 (2008)

Cappellaro, Paola

2009-03-01

133

Highly sensitive molecular detection with swift heavy ions  

NASA Astrophysics Data System (ADS)

Various imaging techniques using microbeam have been applied in biology. Secondary ion mass spectrometry (SIMS) is one of the prominent tools for biological imaging; SIMS can provide data on molecular distribution in biological samples smaller than 1 ?m. However, conventional SIMS has only low sensitivity for molecular ions; therefore there is a need for beams of more sensitive primary ions. Plasma desorption mass spectrometry (PDMS) is a method using high energy fission fragments from excitation of a 252Cf source, and it allows ionization of large molecules (typically up to 20 kDa) due to the dense electronic excitation. Although PDMS is not in use today because of the development of soft ionization methods, ionization induced by high energy ion collision still remains the only method which combines high spatial resolution and sensitive detection of large molecules. In this work, the secondary ion yield of amino acid and phospholipid was measured for 6 MeV Cu4+. The yields were compared to bismuth cluster ions, which achieve relatively high yield. It was confirmed that the swift heavy ion has a couple of hundred times higher yield for large molecules than bismuth cluster ions.

Wakamatsu, Yoshinobu; Yamada, Hideaki; Ninomiya, Satoshi; Jones, Brian N.; Seki, Toshio; Aoki, Takaaki; Webb, Roger; Matsuo, Jiro

2011-10-01

134

Development of high-sensitivity SWIR APD receivers  

NASA Astrophysics Data System (ADS)

Emerging short wavelength infrared (SWIR) LIght Detection And Ranging (LIDAR) and long range laser rangefinder systems, require large optical aperture avalanche photodiodes (APDs) receivers with high sensitivity and high bandwidth. A large optical aperture is critical to increase the optical coupling efficiency and extend the LIDAR sensing range of the above systems. Both APD excess noise and transimpedance amplifier (TIA) noise need to be reduced in order to achieve high receiver sensitivity. The dark current and capacitance of large area APDs increase with APD aperture and thus limit the sensitivity and bandwidth of receivers. Spectrolab has been developing low excess noise InAlAs/InGaAs APDs with impact ionization engineering (I2E) designs for many years and has demonstrated APDs with optical gain over 100 utilizing multiple period I2E structures in the APD multiplier. These high gain I2E APDs have an excess noise factor less than 0.15. With an optical aperture of 200 ?m, low excess noise multiple periods I2E APDs have capacitances about 1.7 pF. In addition, optical gains of InAlAs based APDs show very little temperature dependence and will enable APD photoreceivers without thermal electric cooling.

Bai, Xiaogang; Yuan, Ping; Chang, James; Sudharsanan, Rengarajan; Krainak, Michael; Yang, Guangning; Sun, Xiaoli; Lu, Wei

2013-06-01

135

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

136

New hyphenated methodologies in high-sensitivity glycoprotein analysis  

PubMed Central

High-sensitivity glycoprotein analyses are of particular interest in modern biomedical and clinical research, as well as in the development of recombinant protein products. The evolution of new hyphenated methodologies in high-sensitivity glycoprotein analysis is highlighted in this thematic review. These methodologies include, in particular, capillary LC/MALDI/TOF/TOF MS in conjunction with online permethylation platform, and silica-based lectin microcolumns interfaced to MS. The potential of these methodologies in glycomic and glycoproteomic analysis is demonstrated for model glycoproteins as well as total glycomes and glycoproteomes derived from biological samples. Additionally, the applications of CE-MS, CEC, and nanoLC with graphitized carbon in the areas of glycomics and glycoproteomics are described.

Novotny, Milos V.; Mechref, Yehia

2006-01-01

137

A High Sensitivity Bio Photosensor for Detecting a Luciferase Bioluminescence  

NASA Astrophysics Data System (ADS)

A high sensitivity CMOS bio photosensor applicable to a bioluminescent assay was developed with a 0.18µm CMOS image sensor (CIS) process. The bio photosensor consisting of a photosensor and a PWM 20bit A/D converter achieved high sensitivity for detecting a extremely low bioluminescence due to a large photodiode area, a long exposure time and the other noise reduction techniques. The bio photosensor chip has a 2×4 sensor array on a 2.45×2.45mm2 die. Experimental results with the bioluminescence showed the chip can detect below 10-5lux luminescence at room temperature and the power consumption is 32µW.

Kameda, Seiji; Moriyama, Yusuke; Noda, Kenichi; Iwata, Atsushi

138

Are inflationary predictions sensitive to very high energy physics?  

Microsoft Academic Search

It has been proposed that the successful inflationary description of density perturbations on cosmological scales is sensitive to the details of physics at extremely high (trans-Planckian) energies. We test this proposal by examining how inflationary predictions depend on higher-energy scales within a simple model where the higher-energy physics is well understood. We find the best of all possible worlds: inflationary

Clifford P. Burgess; James M. Cline; Richard Holman

2003-01-01

139

A highly sensitive thermistor bolometer for a clinical tympanic thermometer  

Microsoft Academic Search

A newly designed infrared radiation sensor for a clinical tympanic thermometer has been developed. A very small packaging size (2.2 mm × 2.3 mm × 0.8 mm) is achieved so that the sensor can be used in the human auricle. To realize high sensitivity, infrared sensing regions in the shape of a pair of micro-air-bridges are encapsulated in a vacuum

Takeshi Kudoh; Shin-ichiro Ikebe; Hiroaki Satow; Kiyoshi Komatsu; Mitsuteru Kimura

1996-01-01

140

A combination of sensitizers with high LET radiations.  

PubMed Central

Preliminary measurements of OER for pion beams in combination with a concentration of Misonidazole (0.4 mM) that is realistic in radiotherapeutic application are reported. These results indicate that 0.4 mM of misonidazole is as effective in reducing OER for negative pions as for X-rays. The application of high LET radiations in combination with hypoxic cell sensitizers is discussed.

Raju, M. R.; Amols, H. I.; Carpenter, S. G.

1978-01-01

141

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

142

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

143

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

144

A simple, tunable, and highly sensitive radio-frequency sensor  

NASA Astrophysics Data System (ADS)

We report a radio frequency (RF) sensor that exploits tunable attenuators and phase shifters to achieve high-sensitivity and broad band frequency tunability. Three frequency bands are combined to enable sensor operations from ~20 MHz to ~38 GHz. The effective quality factor (Qeff) of the sensor is as high as ~3.8 × 106 with 200 ?l of water samples. We also demonstrate the measurement of 2-proponal-water-solution permittivity at 0.01 mole concentration level from ~1 GHz to ~10 GHz. Methanol-water solution and de-ionized water are used to calibrate the RF sensor for the quantitative measurements.

Cui, Yan; Sun, Jiwei; He, Yuxi; Wang, Zheng; Wang, Pingshan

2013-08-01

145

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

PubMed Central

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 mm2 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.

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

2011-01-01

146

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

2011-04-01

147

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

148

High-sensitivity photoacoustic absorption spectroscopy of nonlinear optical materials  

NASA Astrophysics Data System (ADS)

Nonlinear optical materials are important to extend the spectral coverage of existing lasers, mainly via frequency doubling and with optical parametric oscillators. The quality of the materials and components, e.g. in terms of residual absorption, is pivotal for the performance of the devices. The paper presents high-sensitivity absorption measurements of nonlinear optical materials. They were performed using a photoacoustic spectrometer which combines high sensitivity with broad spectral coverage. This allows one not only to quantify the level of residual absorption but also to assist in the characterization of the materials in terms of optically relevant impurities and imperfections. The spectrometer covers the wavelength range between 407 and 2600 nm using a pulsed optical parametric oscillator as excitation source. Pulse energies up to 100 mJ allow one to record absorption spectra with a sensitivity down to 10 ppm/cm. The paper presents spectra of lithium niobate and lithium triborate crystals which are important for highpower nonlinear optical applications. The results are discussed with respect to material impurities and the suitability of individual samples for frequency conversion.

Waasem, Niklas; Buse, Karsten; Kühnemann, Frank

2013-03-01

149

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

150

Compact low-power high-sensitivity angle sensor  

NASA Astrophysics Data System (ADS)

We present the design of a compact battery-powered optical angle sensor, together with the first results obtained using the prototype measuring system. The output of the sensor is proportional to cos 2? over a full 360°, where ? is the (possibly static) angle of rotation from a designated zero orientation. Over the more limited range of approximately +/-20° the measured angular sensitivity is in excess of 70 mV/°, corresponding to an angular resolution of +/-0.01°. Although the cos 2? dependency was created in order to meet the requirements of a dynamical quadrupole measuring instrument, this sensor could be useful in applications which require a highly sensitive, yet compact, contactless, measurement of rotation, over (say) +/-20°.

Lockerbie, N. A.; McDonald, N. J.; Weston, R. G.

2004-04-01

151

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

152

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

153

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

154

A CMOS In-Pixel CTIA High Sensitivity Fluorescence Imager.  

PubMed

Traditionally, charge coupled device (CCD) based image sensors have held sway over the field of biomedical imaging. Complementary metal oxide semiconductor (CMOS) based imagers so far lack sensitivity leading to poor low-light imaging. Certain applications including our work on animal-mountable systems for imaging in awake and unrestrained rodents require the high sensitivity and image quality of CCDs and the low power consumption, flexibility and compactness of CMOS imagers. We present a 132×124 high sensitivity imager array with a 20.1 ?m pixel pitch fabricated in a standard 0.5 ? CMOS process. The chip incorporates n-well/p-sub photodiodes, capacitive transimpedance amplifier (CTIA) based in-pixel amplification, pixel scanners and delta differencing circuits. The 5-transistor all-nMOS pixel interfaces with peripheral pMOS transistors for column-parallel CTIA. At 70 fps, the array has a minimum detectable signal of 4 nW/cm(2) at a wavelength of 450 nm while consuming 718 ?A from a 3.3 V supply. Peak signal to noise ratio (SNR) was 44 dB at an incident intensity of 1 ?W/cm(2). Implementing 4×4 binning allowed the frame rate to be increased to 675 fps. Alternately, sensitivity could be increased to detect about 0.8 nW/cm(2) while maintaining 70 fps. The chip was used to image single cell fluorescence at 28 fps with an average SNR of 32 dB. For comparison, a cooled CCD camera imaged the same cell at 20 fps with an average SNR of 33.2 dB under the same illumination while consuming over a watt. PMID:23136624

Murari, Kartikeya; Etienne-Cummings, Ralph; Thakor, Nitish; Cauwenberghs, Gert

2011-03-24

155

A CMOS In-Pixel CTIA High Sensitivity Fluorescence Imager  

PubMed Central

Traditionally, charge coupled device (CCD) based image sensors have held sway over the field of biomedical imaging. Complementary metal oxide semiconductor (CMOS) based imagers so far lack sensitivity leading to poor low-light imaging. Certain applications including our work on animal-mountable systems for imaging in awake and unrestrained rodents require the high sensitivity and image quality of CCDs and the low power consumption, flexibility and compactness of CMOS imagers. We present a 132×124 high sensitivity imager array with a 20.1 ?m pixel pitch fabricated in a standard 0.5 ? CMOS process. The chip incorporates n-well/p-sub photodiodes, capacitive transimpedance amplifier (CTIA) based in-pixel amplification, pixel scanners and delta differencing circuits. The 5-transistor all-nMOS pixel interfaces with peripheral pMOS transistors for column-parallel CTIA. At 70 fps, the array has a minimum detectable signal of 4 nW/cm2 at a wavelength of 450 nm while consuming 718 ?A from a 3.3 V supply. Peak signal to noise ratio (SNR) was 44 dB at an incident intensity of 1 ?W/cm2. Implementing 4×4 binning allowed the frame rate to be increased to 675 fps. Alternately, sensitivity could be increased to detect about 0.8 nW/cm2 while maintaining 70 fps. The chip was used to image single cell fluorescence at 28 fps with an average SNR of 32 dB. For comparison, a cooled CCD camera imaged the same cell at 20 fps with an average SNR of 33.2 dB under the same illumination while consuming over a watt.

Murari, Kartikeya; Etienne-Cummings, Ralph; Thakor, Nitish; Cauwenberghs, Gert

2012-01-01

156

High-sensitivity uncooled microcantilever infrared imaging arrays  

NASA Astrophysics Data System (ADS)

The design and operation of an advanced bimorph microcantilever based infrared imaging detector are presented. This technology has the potential to achieve very high sensitivities due to its inherent high responsivity and low noise sensor and detection electronics. The sensor array is composed of bimaterial, thermally sensitive microcantilever structures that are the moving elements of variable plate capacitors. The heat sensing microcantilever structures are integrated with CMOS control and amplification electronics to produce a low cost imager that is compatible with standard silicon IC foundry processing and materials. The bimorph sensor structure is fabricated using low thermal expansion, high thermal isolation silicon oxide and oxynitride materials, and a high thermal expansion aluminum alloy bimetal. The microcantilever paddle is designed to move away from the substrate at elevated imaging temperatures, leading to large modeled sensor dynamic ranges (~16 bits). A temperature coefficient of capacitance, ?C/C, (equivalent to TCR for microbolometers) above 30% has been modeled and measured for these structures, leading to modeled NEDT < 20 mK and thermal time constants in the 5-10 msec range giving a figure-of-merit [1] NEDT.Tau = 100-200 mK.msec. The development efforts to date have focused on the fabrication of 160x120 pixel arrays with 50 micron pitch pixels. Results from detailed thermo-electro-opto-mechanical modeling of the operation of these sensors are compared with experimental measurements from various test and integrated sensor structures and arrays.

Hunter, Scott R.; Maurer, Gregory; Jiang, Lijun; Simelgor, Gregory

2006-06-01

157

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

158

High sensitivity of tidewater outlet glacier dynamics to shape  

NASA Astrophysics Data System (ADS)

Variability in tidewater outlet glacier behavior under similar external forcing has been attributed to differences in outlet shape (i.e., bed elevation and width), but this dependence has not been investigated in detail. Here we use a numerical ice flow model to show that the dynamics of tidewater outlet glaciers under external forcing are highly sensitive to width and bed topography. Our sensitivity tests indicate that for glaciers with similar discharge, the trunks of wider glaciers and those grounded over deeper basal depressions tend to be closer to flotation, so that less dynamically induced thinning results in rapid, unstable retreat following a perturbation. The lag time between the onset of the perturbation and unstable retreat varies with outlet shape, which may help explain intra-regional variability in tidewater outlet glacier behavior. Further, because the perturbation response is dependent on the thickness relative to flotation, varying the bed topography within the range of observational uncertainty can result in either stable or unstable retreat due to the same perturbation. Thus, extreme care must be taken when interpreting the future behavior of actual glacier systems using numerical ice flow models that are not accompanied by comprehensive sensitivity analyses.

Enderlin, E. M.; Howat, I. M.; Vieli, A.

2013-06-01

159

High sensitivity of tidewater outlet glacier dynamics to shape  

NASA Astrophysics Data System (ADS)

Variability in tidewater outlet glacier behavior under similar external forcing has been attributed to differences in outlet shape (i.e. bed elevation and width), but this dependence has not been investigated in detail. Here we use a numerical ice flow model to show that the dynamics of tidewater outlet glaciers under external forcing are highly sensitive to width and bed topography. Our sensitivity tests indicate that for glaciers with similar discharge, the trunks of wider glaciers and those grounded over deeper basal depressions tend to be closer to flotation, so that less dynamically induced thinning results in rapid, unstable retreat following a perturbation. The lag time between the onset of the perturbation and unstable retreat varies with outlet shape, which may help explain intra-regional variability in tidewater outlet glacier behavior. Further, because the perturbation response is dependent on the thickness relative to flotation, varying the bed topography within the range of observational uncertainty can result in either stable or unstable retreat due to the same perturbation. Thus, extreme care must be taken when interpreting the future behavior of actual glacier systems using numerical ice flow models that are not accompanied by comprehensive sensitivity analyses.

Enderlin, E. M.; Howat, I. M.; Vieli, A.

2013-02-01

160

Mechanoreceptors in calanoid copepods: designed for high sensitivity.  

PubMed

The mechanoreceptors of the first antennae of Pleuromamma xiphias, a mesopelagic calanoid copepod, are critical for the detection of potential threats. These receptors exceed the physiological performance of other crustacean mechanoreceptors in sensitivity to water velocities as well as in frequency response. A study of these receptors was initiated to elucidate structure-function relationships. Morphologically, the receptors resemble the arthropod scolopidial organs by the presence of a scolopale tube. However, the rigidity of the copepod receptors greatly exceeds those described for crustaceans and other arthropods. The scolopale tube completely encloses the distal dendrites and it is firmly anchored to the cuticle. Microtubules are organized in register and arise from microtubule subfibers associated with crescent-shaped rods which extend from the basal body region to the setal socket. The distal dendrites are filled with a large number of cross-linked microtubules. Termination of the distal dendrites inside the lumen of the setae is gradual with a firm anchoring to the cuticle. A likely mechanism for mechanotransduction would involve a linkage between individual microtubules and mechano-gated channels in the dendritic membrane. The rigidity probably contributes to the high frequency sensitivity, and termination of the dendrite inside the seta increases the overall sensitivity of these receptors. PMID:18088933

Weatherby, T M; Lenz, P H

2000-01-01

161

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

162

Selectively coated photonic crystal fiber for highly sensitive fluorescence detection  

NASA Astrophysics Data System (ADS)

The authors investigate the potential of hollow core photonic crystal fibers (HCPCFs) for highly sensitive fluorescence detection by selectively coating the central hole of a HCPCF with fluorophores. After studying the influence of reabsorption and intermolecular effects on the emission, they show that dye concentrations down to 10-9M can be detected using only nanoliter sample volumes. The results indicate that HCPCF are well suited for sensing applications involving internal emission or scattering processes, such as fluorescence based gas sensing or surface-enhanced Raman scattering, and may be integrated into compact optical devices.

Smolka, Stephan; Barth, Michael; Benson, Oliver

2007-03-01

163

A new correlation method for high sensitivity current noise measurements.  

PubMed

The properties of a differential transconductance amplifier coupled with a four channel measurement system are exploited in order to reach a very high sensitivity in current noise measurements. In particular, it is demonstrated that, in proper conditions, the noise contributions coming from the active and passive devices that make up the transresistance amplifier can be virtually eliminated. Moreover, the proposed measurement method allows the evaluation of the impedance of the device under test from noise measurement data. Actual measurement results are also reported that demonstrate the effectiveness of the proposed approach. PMID:18052495

Ciofi, Carmine; Scandurra, Graziella; Merlino, Rosario; Cannatà, Gianluca; Giusi, Gino

2007-11-01

164

Identification and Quantification of Several Mammalian Steroid Hormones in Plants by UPLC-MS\\/MS  

Microsoft Academic Search

We have developed an effective method for the isolation, identification, and quantification of several mammalian steroid hormones\\u000a and their metabolites in different plant tissues. The purification protocol was based on solid-phase extraction (SPE) combined\\u000a with immunoaffinity chromatography (IAC) using immobilized generic polyclonal anti-?4-3-keto-steroid antibodies covalently bound to Affi-Gel 10 sorbent. The antibodies were characterized by means of enzyme-linked\\u000a immunosorbent assay

Radim Simerský; Ond?ej Novák; David A. Morris; Vladimír Pouzar; Miroslav Strnad

2009-01-01

165

Ultra high resolution ultra high sensitive optical micro-angiography based on super continuum light source  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate for the first time utilizing a super continuum light source to achieve ultra high sensitive Optical Micro-Angiography (UHS-OMAG) system. The broad band light with central wavelength around 800nm, emitted from the super continuum light source, could provide a ~2?m coherence gate for the system. Based on a fast CMOS camera, we could successfully develop a high speed (~70 kHz line rate) Fourier Domain Optical coherence tomography system. Applying the ultra high sensitive OMAG algorithm onto the system, we could visualize blood vessel networks buried within the tissue bed in a high resolution and high sensitivity mode. The modality is performed on imaging the human finger nail fold and the mouse pinna to obtain both high resolution structure image and detailed blood perfusion map. The excellent performance shows a great potential of our system in future biological imaging application.

An, Lin; Qin, Jia; Zhi, Zhongwei; Wang, Ruikang

2011-02-01

166

Quantum-dot-sensitized solar cell with unprecedentedly high photocurrent.  

PubMed

The reported photocurrent density (J(SC)) of PbS quantum dot (QD)-sensitized solar cell was less than 19 mA/cm(2) despite the capability to generate 38 mA/cm(2), 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 J(SC) of 30 mA/cm(2). By Hg(2+) doping into PbS, J(SC) is almost doubled with improved stability. Femtosecond transient study confirms that the improved J(SC) 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 Hg(2+), which is responsible for the enhanced electron injection, suppressed recombination and stability. Thanks to the extremely high J(SC), power conversion efficiency of 5.6% is demonstrated at one sun illumination. PMID:23308343

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

2013-01-10

167

Highly sensitive and specific bioassay for measuring bioactive TGF-?  

PubMed Central

Background Transforming Growth Factor-? (TGF-?) regulates key biological processes during development and in adult tissues and has been implicated in many diseases. To study the biological functions of TGF-?, sensitive, specific, and convenient bioassays are necessary. Here we describe a new cell-based bioassay that fulfills these requirements. Results Embryonic fibroblasts from Tgfb1-/- mice were stably transfected with a reporter plasmid consisting of TGF-? responsive Smad-binding elements coupled to a secreted alkaline phosphatase reporter gene (SBE-SEAP). Clone MFB-F11 showed more than 1000-fold induction after stimulation with 1 ng/ml TGF-?1, and detected as little as 1 pg/ml TGF-?1. MFB-F11 cells were highly induced by TGF-?1, TGF-?2 and TGF-?3, but did not show induction with related family members activin, nodal, BMP-2 and BMP-6 or with trophic factors bFGF and BDNF. MFB-F11 cells can detect and quantify TGF-? in biological samples without prior enrichment of TGF-?s, and can detect biologically activated TGF-? in a cell co-culture system. Conclusion MFB-F11 cells can be used to rapidly and specifically measure TGF-? with high sensitivity.

Tesseur, Ina; Zou, Kun; Berber, Elisabeth; Zhang, Hui; Wyss-Coray, Tony

2006-01-01

168

A combined cavity for high sensitivity THz signal detection  

NASA Astrophysics Data System (ADS)

Detection of signals in the THz frequency region is important for applications of THz waves in many areas, such as in medical imaging, forbidden-combined sensing, weapon monitoring, and wireless communications. Cooling system operating under very low temperature, for eliminating the unwanted background THz radiation that exists everywhere in room temperature, sets an obstacle for applications of conventional THz signal detecting systems. We present a combined cavity that can pick out the useful signal in high sensitivity, while the influence of the background THz radiation can be neglected in the detection. The combined cavity consists of a point-defect photonic-crystal resonator and a photonic-crystal WGR. The two resonators are coupled together through optical tunneling to form the combined cavity. Under proper operating parameters, the two resonators are in simultaneous resonance, and the field intensity in the point-defect resonator can be thousands of times of that of an incoming THz signal for a given frequency, so that the sensitivity of detection can be very high. Since the background THz radiation is not in resonance with the cavity, the influence of it to the detection of THz signals wanted can be neglected, and thus cooling systems can be omitted. Plane wave expansion method is used to determine the resonance wavelengths and mode patterns of the cavity. Finite-difference- time-domain method is used to find the quality factors and to simulate the resonance process. Parameter optimization and the conditions for simultaneous resonance of the two cavities are studied.

Ouyang, Zhengbiao; Luo, Xianda; Wang, Jong C.; Liu, Chung Ping; Wu, Chih Jung

2008-03-01

169

Highly efficient monolithic dye-sensitized solar cells.  

PubMed

Monolithic dye-sensitized solar cells (M-DSSCs) provide an effective way to reduce the fabrication cost of general DSSCs since they do not require transparent conducting oxide substrates for the counter electrode. However, conventional monolithic devices have low efficiency because of the impediments resulting from counter electrode materials and spacer layers. Here, we demonstrate highly efficient M-DSSCs featuring a highly conductive polymer combined with macroporous polymer spacer layers. With M-DSSCs based on a PEDOT/polymer spacer layer, a power conversion efficiency of 7.73% was achieved, which is, to the best of our knowledge, the highest efficiency for M-DSSCs to date. Further, PEDOT/polymer spacer layers were applied to flexible DSSCs and their cell performance was investigated. PMID:23432389

Kwon, Jeong; Park, Nam-Gyu; Lee, Jun Young; Ko, Min Jae; Park, Jong Hyeok

2013-03-13

170

Ultra-Sensitive, High Throughput and Quantitative Proteomics Measurements  

SciTech Connect

We describe the broad basis and application of an approach for very high throughput, ultra-sensitive, and quantitative proteomic measurements based upon the use of ultra-high performance separations and mass spectrometry. An overview of the accurate mass and time (AMT) tag approach and a description of the incorporated data analysis pipeline necessary for efficient proteomic studies are presented. Adjunct technologies, including stable-isotope labeling methodologies and improvements in the utilization of LC-MS peak intensity information for quantitative purposes are discussed. Related areas include the use of automated sample handling for improving analysis reproducibility, methods for using information from the separation for more confident peptide peak identification, and the utilization of smaller diameter capillary columns having lower volumetric flow rates to increase electrospray ionization efficiency and allow for more predictable and quantitative results. The developments are illustrated in the context of studies of complex biological systems.

Jacobs, Jon M.; Monroe, Matthew E.; Qian, Weijun; Shen, Yufeng; Anderson, Gordon A.; Smith, Richard D.

2005-02-01

171

Highly sensitive detection of urinary cadmium to assess personal exposure.  

PubMed

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(-1) cm(-2)) and low background current (<4 nA). When an array of ultramicroelectrodes was positioned with optimal spacing, these BDD sensors showed a sigmoidal diffusion behavior. They also demonstrated high accuracy with linear dose dependence for quantification of cadmium in a certified reference river water sample from the U.S. National Institute of Standards and Technology (NIST) as well as in a human urine sample spiked with 0.25-1 ppb cadmium. PMID:23561905

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

2013-03-01

172

Correcting systematic errors in high-sensitivity deuteron polarization measurements  

NASA Astrophysics Data System (ADS)

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

Brantjes, N. P. M.; Dzordzhadze, V.; Gebel, R.; Gonnella, F.; Gray, F. E.; van der Hoek, D. J.; Imig, A.; Kruithof, W. L.; Lazarus, D. M.; Lehrach, A.; Lorentz, B.; Messi, R.; Moricciani, D.; Morse, W. M.; Noid, G. A.; Onderwater, C. J. G.; Özben, C. S.; Prasuhn, D.; Levi Sandri, P.; Semertzidis, Y. K.; da Silva E Silva, M.; Stephenson, E. J.; Stockhorst, H.; Venanzoni, G.; Versolato, O. O.

2012-02-01

173

Improvement of sensitivity in high-resolution ERDA  

NASA Astrophysics Data System (ADS)

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 Mylar foil. By measuring the ion signal in coincidence with the electron signal, the dark noise of the ion detector can be efficiently rejected. This new detector system is used to improve the sensitivity of high-resolution elastic recoil detection. The detection limit of 0.08 at.% is achieved for the boron depth profiling in Si.

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

2012-02-01

174

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

175

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

176

Sensitivity study of reliable, high-throughput resolution metricsfor photoresists  

SciTech Connect

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

Anderson, Christopher N.; Naulleau, Patrick P.

2007-07-30

177

Design of a high sensitivity FET integrated MEMS microphone  

Microsoft Academic Search

FET based MEMS microphones comprise of a flexible diaphragm that works as the moving gate of the transistor. The integrated electromechanical transducer can be made more sensitive to external sound pressure either by increasing the mechanical or the electrical sensitivities. We propose a method of increasing the overall sensitivity of the microphone by increasing its electrical sensitivity. The proposed microphone

Malhi Charanjeet kaur; Rudra Pratap; Navakanta Bhat

2009-01-01

178

High-Sensitivity Temperature-Independent Silicon Photonic Microfluidic Biosensors  

NASA Astrophysics Data System (ADS)

Optical biosensors that can precisely quantify the presence of specific molecular species in real time without the need for labeling have seen increased use in the drug discovery industry and molecular biology in general. Of the many possible optical biosensors, the TM mode Si biosensor is shown to be very attractive in the sensing application because of large field amplitude on the surface and cost effective CMOS VLSI fabrication. Noise is the most fundamental factor that limits the performance of sensors in development of high-sensitivity biosensors, and noise reduction techniques require precise studies and analysis. One such example stems from thermal fluctuations. Generally SOI biosensors are vulnerable to ambient temperature fluctuations because of large thermo-optic coefficient of silicon (˜2x10 -4 RIU/K), typically requiring another reference ring and readout sequence to compensate temperature induced noise. To address this problem, we designed sensors with a novel TM-mode shallow-ridge waveguide that provides both large surface amplitude for bulk and surface sensing. With proper design, this also provides large optical confinement in the aqueous cladding that renders the device athermal using the negative thermo-optic coefficient of water (~ --1x10-4RIU/K), demonstrating cancellation of thermo-optic effects for aqueous solution operation near 300K. Additional limitations resulting from mechanical actuator fluctuations, stability of tunable lasers, and large 1/f noise of lasers and sensor electronics can limit biosensor performance. Here we also present a simple harmonic feedback readout technique that obviates the need for spectrometers and tunable lasers. This feedback technique reduces the impact of 1/f noise to enable high-sensitivity, and a DSP lock-in with 256 kHz sampling rate can provide down to micros time scale monitoring for fast transitions in biomolecular concentration with potential for small volume and low cost. In this dissertation, a novel high-sensitivity, athermal biosensor on a TM-mode SOI resonator was designed, fabricated, and evaluated. High-performance biosensing for bulk and surface detection limits of 1x10-7 RIU and 24 fg/mm2 was demonstrated.

Kim, Kangbaek

179

Multisite comparison of high-sensitivity multiplex cytokine assays.  

PubMed

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. PMID:21697338

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; Martínez-Maza, Otoniel; Sinclair, Elizabeth; Borrow, Persephone; Landay, Alan L; Rinaldo, Charles R; Norris, Philip J

2011-06-22

180

Modeling high-efficiency quantum dot sensitized solar cells.  

PubMed

With energy conversion efficiencies in continuous growth, quantum dot sensitized solar cells (QDSCs) are currently under an increasing interest, but there is an absence of a complete model for these devices. Here, we compile the latest developments in this kind of cells in order to attain high efficiency QDSCs, modeling the performance. CdSe QDs have been grown directly on a TiO(2) surface by successive ionic layer adsorption and reaction to ensure high QD loading. ZnS coating and previous growth of CdS were analyzed. Polysulfide electrolyte and Cu(2)S counterelectrodes were used to provide higher photocurrents and fill factors, FF. Incident photon-to-current efficiency peaks as high as 82%, under full 1 sun illumination, were obtained, which practically overcomes the photocurrent limitation commonly observed in QDSCs. High power conversion efficiency of up to 3.84% under full 1 sun illumination (V(oc) = 0.538 V, j(sc) = 13.9 mA/cm(2), FF = 0.51) and the characterization and modeling carried out indicate that recombination has to be overcome for further improvement of QDSC. PMID:20843071

González-Pedro, Victoria; Xu, Xueqing; Mora-Seró, Iván; Bisquert, Juan

2010-10-26

181

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

182

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

183

High-Sensitivity and High-Resolution Contact Hole Patterning by Enhanced-Wettability Developer  

Microsoft Academic Search

We have determined that high-sensitivity and high-resolution contact hole photoresist patterning can be achieved using an optimized combination of developer, added surfactant and ammonium chloride salt. The addition of surfactant improves the wettability of the developer to promote resist dissolution. The presence of ammonium chloride salt protects the sidewall of the contact hole resist pattern to achieve good pattern profile.

Hisayuki Shimada; Shigeki Shimomura; Kouichi Hirose; Tadahiro Ohmi

1993-01-01

184

Modifying interpretations among individuals high in anxiety sensitivity  

PubMed Central

To examine the causal relationship between cognitive biases and anxiety, a bias modification paradigm was used to reduce negative interpretation biases in participants with high anxiety sensitivity (AS). Participants (N=75) were assigned to a Positive training condition or to one of two Control conditions (Neutral or No training). During training, participants imagined themselves in ambiguous scenarios related to AS. Positive training required participants to resolve the scenarios’ ambiguity positively and was hypothesized to result in more positive and less negative subsequent interpretations related to AS, fewer self-reported AS symptoms, and less emotional vulnerability on AS stressors (compared to the Control conditions). As expected, Positive training shifted interpretations of novel scenarios and self-reported AS symptoms in the anticipated direction. Evidence was mixed for the effect of Positive training on emotional vulnerability (small effect for less fear, but not for avoidance). Findings support the causal premise underlying cognitive models of anxiety.

Steinman, Shari A.; Teachman, Bethany A.

2010-01-01

185

A novel, highly sensitive method for assessing gap junctional coupling.  

PubMed

To assess gap junctional intercellular communication we have developed a tracer-based methodology which is both highly sensitive and potentially adaptable for in vivo measurements. We found that injection of serotonin revealed significantly more intercellular communication than that injection of the most permeant synthetic tracer currently in use, neurobiotin. Furthermore, mechanical tracer loading steps can be replaced by transfection with human serotonin transporter and the inclusion of serotonin in the medium. Tracer and transporter are detected using immunocytochemical techniques and the presence of cells that are tracer-positive but transporter-negative indicates junctional communication. Tracer loading in vivo using transgenesis, electroporation or viral transduction to direct expression of transporter should be more easily accomplished than with mechanical loading methods. PMID:23958747

Hou, Mingli; Li, Yaqiao; Paul, David L

2013-08-16

186

Wide Band Power Rectenna with High Sensitivity Detection  

NASA Astrophysics Data System (ADS)

In this study we have developed a new rectenna configuration for wide band of power with high detection sensitivity. This system is based on the use of two Schottky diodes, an HSM2820 for large signal applications and an HSMS2850 for small signal applications. To be able to integrate the both diodes in the same rectenna system this demands the achievement of a RF limiter which will protect the RF- DC converter based on the use of the HSMS2850. Then the goal of this research is to design a microwave wide band limiter monolithic with a cut off frequency of 20GHz. The process used to develop this limiter is the ED02AH derived from OMMIC. The monolithic circuit achieved has miniatured dimensions with a quasi ideal limiting characteristic.

Zbitou, J.; Latrach, M.; Toutain, S.

2004-12-01

187

Measuring ambient ozone with high sensitivity and bandwidth  

NASA Astrophysics Data System (ADS)

An ozone (O3) analyzer for use in eddy-correlation measurements is described which has an unfiltered bandwidth of at least 20 Hz and sensitivity of at least 0.1 ppbv at 12-Hz bandwidth. Based on chemiluminescence with nitric oxide, it is designed primarily for use on meteorological aircraft, but it also works well for tower measurements. It is significant that the detecting mechanism responds linearly to time-dependent inputs, which is a definite advantage for applications involving measurements of eddy fluxes and spectra O3. The unit is highly specific, the only known interference being a slight quenching of the chemiluminescence by water vapor. The unit does not respond to cloud liquid water or to precipitation, and excellent performance has been obtained in the presence of these two conditions. The entire package weighs 110 kg and requires 360 W at 110 V ac (60 or 400 Hz), and 1200 W at 28 V dc.

Pearson, Richard, Jr.

1990-02-01

188

A 1-D model for highly sensitive tubular reactors  

SciTech Connect

We consider the steady state operation of wall-cooled, fixed-bed tubular reactors. In these reactors the temperature rise ..delta..T must normally be limited to small fractions of the adiabatic temperature rise ..delta..T/sub ad/, both to avoid runaway and maintain product selectivity. Yet ..delta..T/..delta..T/sub ad/ << 1 can only occur if eta = t/sub dif//t/sub reac/ << 1, where t/sub dif/ is the timescale on which heat escapes the reactor by ''diffusing'' to the cooled walls, and t/sub reac/ is the timescale over which the reaction occurs. So here we use asymptotic methods based on eta << 1 to analyze the 2-d reactor equations, and find the radial concentration and temperature profiles to leading order in eta. We then obtain a 1-d model of the reactor by substituting these asymptotically correct profiles into the reactor equations and averaging over r. This model, the ..cap alpha..-model, is identical to the standard (Beek and Singer) 1-d model, except that the reactor's overall heat transfer coefficient U is a decreasing function of the temperature rise ..delta..T. This occurs because as ..delta..T increases, the reaction becomes increasingly concentrated near r = 0, causing a decreased heat transfer efficiency through the reactor's walls. By comparing it with numerical solutions of the original 2-d reactor equations, we find that the ..cap alpha..-model simulates the 2-d equations very accurately, even for highly sensitive reactors operated near runaway. We also find that a runaway criterion derived from the ..cap alpha..-model predicts the runaway transition of the original 2-d equations accurately, especially for highly sensitive reactors. 19 refs.

Hagan, P.S.; Herskowitz, M.; Pirkle, J.C.

1987-01-01

189

A 1-D model for highly sensitive tubular reactors  

SciTech Connect

The authors consider the steady state operation of wall-cooled, fixed-bed tubular reactors. In these reactors the temperature rise ..delta..T must normally be limited to small fractions of the adiabatic temperature rise ..delta..T/sub ad/, both to avoid runaway and maintain product selectivity. Yet ..delta..T/..delta..T/sub ad/<< 1 can only occur if eta = t/sub dif//t/sub reac/ << 1, where t/sub dif/ is the timescale on which heat escapes the reactor by ''diffusing'' to the cooled walls, and t/sub reac/ is the timescale over which the reaction occurs. So here the authors use asymptotic methods based on eta << 1 to analyze the 2-d reactor equations, and find the radial concentration and temperature profiles to leading order in eta. The authors then obtain a 1-d model of the reactor by substituting these asymptotically correct profiles into the reactor equations and averaging over r. This model, the ..cap alpha..-model, is identical to the standard (Beek and Singer) 1-d model, except that the reactor's overall heat transfer coefficient U is a decreasing function at the temperature rise ..delta..T. This occurs because as ..delta..T increases, the reaction becomes increasingly concentrated near r=O, causing a decreased heat transfer efficiency through the reactor's wall. By comparing it with numerical solutions of the original 2-d reactor equations, the authors find that the ..cap alpha..-model simulates the 2-d equations very accurately, even for highly sensitive reactors operated near runaway. They also find that a runaway criterion derived from the ..cap alpha..-model predicts the runaway transition of the original 2-d equations accurately, especially for highly sensitive reactors.

Hagan, P.S.; Herskowitz, M.; Pirkle, J.C.

1987-01-01

190

Dewar-cooler-integrated high sensitivity MWIR wave front sensor  

NASA Astrophysics Data System (ADS)

Recent developments in the Mid Wave InfraRed (MWIR) optical domain were made on materials, optical design and manufacturing. They answer increasing demands for more compact, less temperature dependent optical systems with increased optical performances and complexity (multi- or hyper- spectral imagery). At the same time, the characterization of these components has become strategic and requires solutions with higher performance. The optical quality of such devices is measured by wave front sensing techniques. PHASICS previously developed wave front sensors based on Quadri-Wave Lateral Shearing Interferometry (QWLSI) using broadband microbolometers cameras for infrared measurements. However they suffer from reduced light sensitivity in the MWIR domain, which limits their use with broadband sources such as black bodies. To meet metrology demands, we developed an innovative wave front sensor. This instrument combines the metrological qualities of QWLSI with the radiometric performances of a last generation detection block (Infrared Detector Dewar Cooler Assembly, IDDCA) with a quantum infrared focal plane array (IRFPA) of HgCdTe technology. The key component of QWLSI is a specific diffractive grating placed a few millimeters from the focal plane array. This requirement implies that this optics should be integrated inside the IDDCA. To achieve this, we take advantage of the experience acquired from recent developments with optics integrated in IDDCA. Thanks to this approach, we developed a high spatial resolution MWIR wave front sensor (160x128 points) with a high sensitivity for accurate measurements under low-flux conditions. This paper will present the instrument technological solutions, the development key steps and experimental results on various metrology applications.

Velghe, Sabrina; Magli, Serge; Aubry, Gilles; Guérineau, Nicolas; Rommeluère, Sylvain; Jaeck, Julien; Wattellier, Benoit

2013-06-01

191

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

192

High sensitivity protein assays on microarray silicon slides.  

PubMed

In this work, we report on the improvement of microarray sensitivity provided by a crystalline silicon substrate coated with thermal silicon oxide functionalized by a polymeric coating. The improvement is intended for experimental procedures and instrumentations typically involved in microarray technology, such as fluorescence labeling and a confocal laser scanning apparatus. The optimized layer of thermally grown silicon oxide (SiO(2)) of a highly reproducible thickness, low roughness, and fluorescence background provides fluorescence intensification due to the constructive interference between the incident and reflected waves of the fluorescence radiation. The oxide surface is coated by a copolymer of N,N-dimethylacrylamide, N-acryloyloxysuccinimide, and 3-(trimethoxysilyl)propyl methacrylate, copoly(DMA-NAS-MAPS), which forms, by a simple and robust procedure, a functional nanometric film. The polymeric coating with a thickness that does not appreciably alter the optical properties of the silicon oxide confers to the slides optimal binding specificity leading to a high signal-to-noise ratio. The present work aims to demonstrate the great potential that exists by combining an optimized reflective substrate with a high performance surface chemistry. Moreover, the techniques chosen for both the substrate and surface chemistry are simple, inexpensive, and amenable to mass production. The present application highlights their potential use for diagnostic applications of real clinical relevance. The coated silicon slides, tested in protein and peptide microarrays for detection of specific antibodies, lead to a 5-10-fold enhancement of the fluorescence signals in comparison to glass slides. PMID:19485342

Cretich, Marina; di Carlo, Gabriele; Longhi, Renato; Gotti, Cecilia; Spinella, Natalia; Coffa, Salvatore; Galati, Clelia; Renna, Lucio; Chiari, Marcella

2009-07-01

193

High-sensitivity and high-dry-etching durability positive-type electron-beam resist  

NASA Astrophysics Data System (ADS)

As feature sizes of semiconductors grow smaller, a resist having dry etching durability and high sensitivity is required for electron beam lithography. However, the positive type electron beam resist having both high sensitivity and high dry etching durability, which suits for practical use, has not been developed yet. In order to solve this problem, a homologous series of poly(alkyl 2-cyanoacrylate) has been investigated. As a result, the new positive type electron beam resist having high sensitivity, high dry etching durability, and high thermal resistance has been developed. This new type of resist consists of poly(cyclohexyl 2- cyanoacrylate), and these features of this resist are due to the cyano and the cyclohexyl groups. The dry etching durability of this resist is 2.19 times as high as that of poly(mthyl methacrylate) (PMMA). The sensitivity is 1.7 (mu) C/cm2 at accelerating voltage of 20 kV, which is about the same as that of poly(butene-1-sulfone) (PBS). Moreover, poly(cyclohexyl 2-cyanoacrylate) has the glass transition of 152 degree(s)C, and then it is thermally stable. Using this resist in photomask fabrication by dry etching, the chrome linewidth uniformity of 0.034 micrometers 3 (sigma) can be obtained.

Tamura, Akira; Yonezawa, Masaji; Sato, Mitsuyoshi; Fujimoto, Yoshiaki

1991-08-01

194

Highly-sensitive and high-resolution all-fiber three-dimensional measurement system  

NASA Astrophysics Data System (ADS)

A practical all-fiber three-dimensional measurement system is demonstrated with an incoherent interferometer at the eye-safe wavelength of 1.55 ?m. The sensitivity and axial resolution are as high as 102 dB and 1.4 ?m from a few meters' distance, respectively. A rotating scanner is developed for axial scanning, and a wide longitudinal scanning range of 54 mm is demonstrated. The high resolution images of a few samples are clearly obtained at the speed of 52 points/s. Moreover, the resolution, sensitivity, speed, and angle dependence are discussed for measurement of a 100 yen Japanese coin.

Ohta, Takefumi; Nishizawa, Norihiko; Ozawa, Tetsuya; Itoh, Kazuyoshi

2008-05-01

195

Wide bandwidth transimpedance amplifier for extremely high sensitivity continuous measurements.  

PubMed

This article presents a wide bandwidth transimpedance amplifier based on the series of an integrator and a differentiator stage, having an additional feedback loop to discharge the standing current from the device under test (DUT) to ensure an unlimited measuring time opportunity when compared to switched discharge configurations while maintaining a large signal amplification over the full bandwidth. The amplifier shows a flat response from 0.6 Hz to 1.4 MHz, the capability to operate with leakage currents from the DUT as high as tens of nanoamperes, and rail-to-rail dynamic range for sinusoidal current signals independent of the DUT leakage current. Also available is a monitor output of the stationary current to track experimental slow drifts. The circuit is ideal for noise spectral and impedance measurements of nanodevices and biomolecules when in the presence of a physiological medium and in all cases where high sensitivity current measurements are requested such as in scanning probe microscopy systems. PMID:17902966

Ferrari, Giorgio; Sampietro, Marco

2007-09-01

196

High-sensitivity CCD-based x-ray detector.  

SciTech Connect

The detector is designed for imaging measurements requiring relatively high sensitivity and high spatial resolution. The detector can discriminate single X-ray photons, yet has the wide dynamic range ({approx}10000:1) associated with integrating detectors. A GdO{sub 2}S{sub 2} phosphor screen converts the incoming X-ray image into an optical image. The optical image is coupled (without demagnification) to the CCD image sensor using a fiber optic faceplate. The CCD (Philips Semiconductors) has an area of 4.9 x 8.6 cm with 4000 x 7000 12 {mu}m pixels. A single 12 keV X-ray photon produces a signal of 100 e-. With 2 x 2 pixel binning, the total noise per 24 {mu}m pixel in a 100 s image is {approx}30 e-, the detective quantum efficiency is >0.6 at 1 X-ray photon per pixel, and the full image can be read out in <4 s. The spatial resolution is 50 {mu}m. The CCD readout system is fully computer-controlled, allowing flexible operation in time-resolved experiments. The detector has been characterized using visible-light images, X-ray images and time-resolved muscle diffraction measurements.

Phillips, W. C.; Stewart, A.; Stanton, M.; Naday, I.; Ingersoll, C.; Electronics and Computing Technologies Division; Brandeis Univ.

2002-01-01

197

A Systems Biology Strategy Reveals Biological Pathways and Plasma Biomarker Candidates for Potentially Toxic Statin-Induced Changes in Muscle  

Microsoft Academic Search

BackgroundAggressive lipid lowering with high doses of statins increases the risk of statin-induced myopathy. However, the cellular mechanisms leading to muscle damage are not known and sensitive biomarkers are needed to identify patients at risk of developing statin-induced serious side effects.MethodologyWe performed bioinformatics analysis of whole genome expression profiling of muscle specimens and UPLC\\/MS based lipidomics analyses of plasma samples

Reijo Laaksonen; Mikko Katajamaa; Hannu Päivä; Marko Sysi-Aho; Lilli Saarinen; Päivi Junni; Dieter Lütjohann; Joél Smet; Rudy van Coster; Tuulikki Seppänen-Laakso; Terho Lehtimäki; Juhani Soini; Matej Oresic; Andrea Califano

2006-01-01

198

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

199

Improvement of sensitivity in high-resolution Rutherford backscattering spectroscopy  

SciTech Connect

The sensitivity (limit of detection) of high-resolution Rutherford backscattering spectroscopy (HRBS) is mainly determined by the background noise of the spectrometer. There are two major origins of the background noise in HRBS, one is the stray ions scattered from the inner wall of the vacuum chamber of the spectrometer and the other is the dark noise of the microchannel plate (MCP) detector which is commonly used as a focal plane detector of the spectrometer in HRBS. In order to reject the stray ions, several barriers are installed inside the spectrometer and a thin Mylar foil is mounted in front of the detector. The dark noise of the MCP detector is rejected by the coincidence measurement with the secondary electrons emitted from the Mylar foil upon the ion passage. After these improvements, the background noise is reduced by a factor of 200 at a maximum. The detection limit can be improved down to 10 ppm for As in Si at a measurement time of 1 h under ideal conditions.

Hashimoto, H.; Nakajima, K.; Suzuki, M.; Kimura, K. [Department of Micro Engineering, Kyoto University, Kyoto 606-8501 (Japan); Sasakawa, K. [Department of Micro Engineering, Kyoto University, Kyoto 606-8501 (Japan); Kobelco Research Institute, Inc., Takatsukadai 1-5-5, Nishi-ku, Kobe 651-2271 (Japan)

2011-06-15

200

A Highly Sensitive Genetic Protocol to Detect NF1 Mutations  

PubMed Central

Neurofibromatosis type 1 (NF1) is a hereditary disorder caused by mutations in the NF1 gene. Detecting mutation in NF1 is hindered by the gene's large size, the lack of mutation hotspots, the presence of pseudogenes, and the wide variety of possible lesions. We developed a method for detecting germline mutations by combining an original RNA-based cDNA-PCR mutation detection method and denaturing high-performance liquid chromatography (DHPLC) with multiplex ligation-dependent probe amplification (MLPA). The protocol was validated in a cohort of 56 blood samples from NF1 patients who fulfilled NIH diagnostic criteria, identifying the germline mutation in 53 cases (95% sensitivity). The efficiency and reliability of this approach facilitated detection of different types of mutations, including single-base substitutions, deletions or insertions of one to several nucleotides, microdeletions, and changes in intragenic copy number. Because mutational screening for minor lesions was performed using cDNA and the characterization of mutated alleles was performed at both the RNA and genomic DNA level, the analysis provided insight into the nature of the different mutations and their effect on NF1 mRNA splicing. After validation, we implemented the protocol as a routine test. Here we present the overall unbiased spectrum of NF1 mutations identified in 93 patients in a cohort of 105. The results indicate that this protocol is a powerful new tool for the molecular diagnosis of NF1.

Carmen Valero, Maria; Martin, Yolanda; Hernandez-Imaz, Elisabete; Marina Hernandez, Alba; Melean, German; Maria Valero, Ana; Javier Rodriguez-Alvarez, Francisco; Telleria, Dolores; Hernandez-Chico, Concepcion

2011-01-01

201

Capillary photoionization: a high sensitivity ionization method for mass spectrometry.  

PubMed

We present a capillary photoionization (CPI) method for mass spectrometric (MS) analysis of liquid and gaseous samples. CPI utilizes a heated transfer capillary with a vacuum ultraviolet transparent MgF2 window, through which vacuum UV light (10 eV) from an external source enters the capillary. The liquid or gaseous sample, together with dopant, is introduced directly into the heated transfer capillary between the atmosphere and the vacuum of the MS. Since the sample is vaporized and photoionized inside the capillary, ion transmission is maximized, resulting in good overall sensitivity for nonpolar and polar compounds. As in atmospheric pressure photoionization, ionization in CPI occurs either by proton transfer or by charge exchange reactions. The feasibility of CPI was demonstrated with selected nonpolar and polar compounds. A particular advantage of CPI is that it enables the analysis of nonvolatile and nonpolar compounds in liquid samples with high ionization efficiency. This is not possible with existing capillary ionization methods. The performance of CPI as an interface between GC and MS and its applicability for the analysis of steroids in biological samples are also demonstrated. The GC-CPI-MS method shows good chromatographic resolution, linearity (R(2) > 0.993), limits of detection (LOD) in the range of 2-6 pg/mL and repeatability of injection with relative standard deviations of 4-15%. PMID:23713722

Haapala, Markus; Suominen, Tina; Kostiainen, Risto

2013-05-28

202

Physical activity and high-sensitivity C-reactive protein.  

PubMed

Cardiovascular disease (CVD) remains one of the leading causes of death and disability in developed countries around the world despite the documented success of lifestyle and pharmacological interventions. This illustrates the multifactorial nature of atherosclerosis and the use of novel inflammatory markers as an adjunct to risk factor reduction strategies. As evidence continues to accumulate that inflammation is involved in all stages of the development and progression of atherosclerosis, markers of inflammation such as high-sensitivity C-reactive protein (CRP) may provide additional information regarding the biological status of the atherosclerotic lesion. Recent investigations suggest that physical activity reduces CRP levels. Higher levels of physical activity and cardiorespiratory fitness are consistently associated with 6-35% lower CRP levels. Longitudinal training studies that have demonstrated reductions in CRP concentrations range from 16% to 41%, an effect that may be independent of baseline levels of CRP, body composition or weight loss. The average change in CRP associated with physical activity appears to be at least as good, if not better, than currently prescribed pharmacological interventions in similar populations. The primary purpose of this review will be to present evidence from both cross-sectional and longitudinal investigations that physical activity lowers CRP levels in a dose-response manner. Finally, this review will examine factors such as body composition, sex, blood sample timing, diet and smoking, which may influence the CRP response to physical activity. PMID:16646631

Plaisance, Eric P; Grandjean, Peter W

2006-01-01

203

High-sensitivity detection of negative ions in the stratosphere  

NASA Astrophysics Data System (ADS)

High-sensitivity, in situ measurements of the negative ion composition of the stratosphere are presented which have led to the detection of previously unobserved ion species. The balloon-borne measurements were made by an instrument consisting of a cryogenically pumped quadrupole mass filter with single ion detection by a channel electron multiplier operating in a pulse-saturated ion counting mode, with an ion detection limit of about 1 ion/cu cm. Mass spectra taken during a daytime flight over southwestern France at a float altitude of 34 km reveal the presence of ions in the families NO3(-)(HNO3)(a) and HSO4(-)(H2SO4)(b)(HNO3)(c) at fractional ion count rates between 0.9 and 6.5%. Minor ions detected at count rates between 0.05 and 0.4% include those containing NO3(-) and HSO4(-) cores, as well as CN(-) and CO3 and CO3(-).H2O. Ligands identified for these molecules include HNO3 and H2SO4 and, tentatively, H2O, HCl, HNO2 and HOCl. An atmospheric nitric acid concentration of 7 x 10 to the 7th/cu cm is estimated on the basis of the NO3(-) and HNO3 species data.

McCrumb, J. L.; Arnold, F.

1981-11-01

204

Horizontal Hall effect sensor with high maximum absolute sensitivity  

Microsoft Academic Search

Sensitivity of conventional Hall sensors is strongly limited by the well known short-circuit effect. Many researches were devoted to reduce offset and noise but few works were carried out to improve sensitivity. Here, a new shape of integrated horizontal Hall device is presented. This particular shape has been developed to minimize the short-circuit effect of the sensor, allowing one to

J.-B. Kammerer; L. Hebrard; V. Frick; P. Poure; F. Braun

2002-01-01

205

Highly stable and sensitive glucose biosensor based on covalently assembled high density Au nanostructures  

Microsoft Academic Search

We describe the development of a highly stable and sensitive glucose biosensor based on the nanohybrid materials derived from gold nanoparticles (AuNPs) and multi-walled carbon nanotubes (MWCNT). The biosensing platform was developed by using layer-by-layer (LBL) self-assembly of the nanohybrid materials and the enzyme glucose oxidase (GOx). A high density of AuNPs and MWCNT nanocomposite materials were constructed by alternate

Peng Si; Palanisamy Kannan; Longhua Guo; Hungsun Son; Dong-Hwan Kim

2011-01-01

206

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

207

A simple approach to highly sensitive tubular reactors  

SciTech Connect

The steady state operation of a long tubular fixed-bed reactor in which a single highly exothermic reaction is occurring is analyzed. To avoid temperature runaways, such reactors must be operated so that their temperature rises /Delta/T are small fractions of the adiabatic temperature rise /Delta/T/sub ad/. So here asymptotic methods based on /Delta/T//Delta/T/sub ad/L <1 are used to determine the radial temperature and concentration profiles. A simple one-dimensional (z only) reactor model is then derived by substituting these asymptotically correct radial profiles into the full two-dimensional reactor equations and then averaging in r. By comparing with numerical solutions of the two-dimensional reactor equations, it is found that the one-dimensional model accurately simulates the two-dimensional equations, even in the highly sensitive runaway region. It is also shown that a runaway criterion derived from the model accurately predicts the runaway transition of the original two-dimensional reactor equations. Finally, multiple reactions are briefly considered, and it is found that the one-dimensional model does quite well, despite being derived only for the case of a single reaction. One difference to be noted between this one-dimensional model and previous ones is that the overall heat transfer coefficient U is not constant, but is a decreasing function of the temperature rise /Delta/T. This decrease occurs because the heat generation is increasingly concentrated near r = 0 as the reactor approaches runaway, and explains the disagreement between other one-dimensional models and the two-dimensional reactor equations near runaway.

Hagan, P.S.; Herskowitz, M.; Pirkles, C.

1988-10-01

208

High sensitivity 640 x 512 (20?m pitch) microbolometer FPAs  

NASA Astrophysics Data System (ADS)

RVS has made a significant breakthrough in the development of a 640 × 512 array with a unit cell size of 20?m × 20 ?m and performance equivalent to that of the 25?m arrays. The successful development of this array is the first step in achieving mega-pixel formats. This FPA is designed to ultimately achieve performance near the temperature fluctuation limited NETD (<20mK, f/1, 30 Hz). The SB-300 is a highly productized readout and is designed to achieve very good sensitivity (low NETD and low spatial noise) and good dynamic range. The improved performance is through bolometer structure improvements and an innovative ROIC design. It also has a simple and flexible electrical interface which allows external electronics to be small, light, low-cost, and low-power. Almost all adjustments can be made through the serial interface; hence there is no need for external adjustable (DAC) circuitry. The improved power supply rejection helps maintain highly stable detector and strip resistor bias voltages which helps reduce spatial noise and image artifacts. We will show updated performance and imagery on these arrays, which is currently being measured at <30mK, f/1,555 30 Hz. Pixel operability is greater than 99.5% on most FPAs, where the uncorrected responsivity nonuniformity is less than 4% (sigma/mean), and time constant for these arrays was measured at <8msec. We will report detailed FPA performance results including responsivity, noise, uniformity and pixel operability. We also plan to present video imagery from the most recent FPAs. The reduction in pixel size offers several potential benefits for IR systems. For a given system resolution (IFOV) requirement, the 20 ?m pixel will allow an optical volume that is 50 % the size of a 25 ?m based system! We will also provide an update on the enhanced performance and yield producibility of our NVESD ManTech 640 × 480 25 ?m arrays, and also show data on 25 ?m arrays that have been designed for faster time constants (5 ms), while maintaining high performance. We will also show the improvement in our uncooled 320 × 240 and 640 × 480 sensor electronics in terms of reduced power and size for helmet and rifle mounted sensors.

Murphy, D. F.; Ray, M.; Kennedy, A.; Wyles, J.; Hewitt, C.; Wyles, R.; Gordon, E.; Sessler, T.; Baur, S.; Van Lue, D.; Anderson, S.; Chin, R.; Gonzalez, H.; Le Pere, C.; Ton, S.

2006-06-01

209

Strain Rate Sensitivity Estimation from High Velocity Impact Data.  

National Technical Information Service (NTIS)

This experimental study was designed to expand on the work accomplished by Sundararajan and Shewmon in estimating the strain rate sensitivity factors for various materials through the use of simple ballistic impact experiments. The study was divided into ...

M. H. Bednarek

1985-01-01

210

Highly Sensitive and Selective Surface-Enhanced Nanobiosensor.  

National Technical Information Service (NTIS)

Nanosphere lithography (NSL) derived triangular Ag nanoparticles were used to create an extremely sensitive and specific optical biological and chemical nanosensor. Using simple UV-vis spectroscopy, biotinylated surface- confined Ag nanoparticles were use...

A. J. Haes R. P. Van Duyne

2002-01-01

211

High sensitivity imaging Thomson scattering for low temperature plasma  

SciTech Connect

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{sub e}) and 6% in the electron temperature (T{sub e}) at n{sub e}=4x10{sup 19} m{sup -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 9x10{sup 17} m{sup -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{sub e} and T{sub e} measurement is 7x10{sup 20}/n{sub e} J, which means that single shot measurements are possible for n{sub e}>2x10{sup 21} m{sup -3}.

Meiden, H. J. van der; Al, R. S.; Barth, C. J.; Donne, A. J. H.; Goedheer, W. J.; Groot, B. de; Koppers, W. R.; Pol, M. J. van de; Prins, P. R.; Shumack, A. E.; Smeets, P. H. M.; Vijvers, W. A. J.; Westerhout, J.; Wright, G. M.; Rooij, G. J. van [FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Engeln, R. [Eindhoven University of Technology, 5612AZ Eindhoven (Netherlands); Kleyn, A. W. [FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Leiden Institute of Chemistry, Leiden University, Leiden (Netherlands); Lopes Cardozo, N. J.; Schram, D. C. [FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Eindhoven University of Technology, 5612AZ Eindhoven (Netherlands)

2008-01-15

212

Horizontal Hall effect sensor with high maximum absolute sensitivity  

Microsoft Academic Search

The sensitivity of conventional Hall effect sensors is strongly limited by the well-known short-circuit effects. Many researches were devoted to reduce offset and noise, but few works were carried out to improve the sensitivity. Here, a new shape of integrated horizontal Hall effect device is presented. This particular shape has been developed in order to minimize the short-circuit effects in

Jean-Baptiste Kammerer; Luc Hébrard; Vincent Frick; Philippe Poure; Francis Braun

2003-01-01

213

High sensitivity vertical Hall sensor integrated with SOI CMOS  

Microsoft Academic Search

We present the design and performance of the gated vertical Hall sensor integrated with silicon on insulator (SOI) complementary metal oxide semiconductor (CMOS) integrated circuits. We demonstrated almost a factor of ten improvement in sensitivity over the comparable vertical Hall sensor integrated on bulk CMOS i.e. constant voltage and constant current sensitivity of 1200 V\\/V*T versus 130 V\\/V*T and 200mV\\/A*T

A. Peczalski; D. Berndt; D. Sandquist

2003-01-01

214

A terahertz plastic wire based evanescent field sensor for high sensitivity liquid detection  

Microsoft Academic Search

A highly sensitive detection method based on the evanescent wave of a terahertz subwavelength plastic wire was demonstrated for liquid sensing. A 20ppm melamine alcohol solution is successfully identified with refractive-index sensitivity of 0.01.

Borwen You; Ja-Yu Lu; Ci-Ling Pan; Tze-An Liu; Jin-Long Peng

2010-01-01

215

Importance of antitumor immunity for complete cure of highly drug-sensitive leukemia in mice  

Microsoft Academic Search

Seven transplantable leukemia lines were established from spontaneous leukemias and screened for 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-1-(chloroethyl)-1-nitrosourea hydrochloride (ACNU) sensitivity in DDD mice. Three of them were classified as highly sensitive, two as sensitive and two as resistant to ACNU. A highly sensitive line, DL812, was extensively characterized from a therapeutic point of view. DL812 cells were so invasive as to produced enlargement of

Y. Takeda; M. Sekiguchi; A. Matsuzawa

1989-01-01

216

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

217

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

PubMed Central

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.

2013-01-01

218

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

219

Ultra high resolution ultra high sensitive optical micro-angiography based on super continuum light source  

Microsoft Academic Search

In this paper, we demonstrate for the first time utilizing a super continuum light source to achieve ultra high sensitive Optical Micro-Angiography (UHS-OMAG) system. The broad band light with central wavelength around 800nm, emitted from the super continuum light source, could provide a ~2mum coherence gate for the system. Based on a fast CMOS camera, we could successfully develop a

Lin An; Jia Qin; Zhongwei Zhi; Ruikang Wang

2011-01-01

220

High-sensitivity, high-selectivity detection of chemical warfare agents  

Microsoft Academic Search

We report high-sensitivity detection of chemical warfare agents (nerve gases) with very low probability of false positives (PFP). We demonstrate a detection threshold of 1.2 ppb (7.7 mug\\/m3 equivalent of Sarin) with a PFP of <1:106 in the presence of many interfering gases present in an urban environment through the detection of diisopropyl methylphosphonate, an accepted relatively harmless surrogate for

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

2006-01-01

221

Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers  

NASA Astrophysics Data System (ADS)

The development of an electronic skin is critical to the realization of artificial intelligence that comes into direct contact with humans, and to biomedical applications such as prosthetic skin. To mimic the tactile sensing properties of natural skin, large arrays of pixel pressure sensors on a flexible and stretchable substrate are required. We demonstrate flexible, capacitive pressure sensors with unprecedented sensitivity and very short response times that can be inexpensively fabricated over large areas by microstructuring of thin films of the biocompatible elastomer polydimethylsiloxane. The pressure sensitivity of the microstructured films far surpassed that exhibited by unstructured elastomeric films of similar thickness, and is tunable by using different microstructures. The microstructured films were integrated into organic field-effect transistors as the dielectric layer, forming a new type of active sensor device with similarly excellent sensitivity and response times.

Mannsfeld, Stefan C. B.; Tee, Benjamin C.-K.; Stoltenberg, Randall M.; Chen, Christopher V. H.-H.; Barman, Soumendra; Muir, Beinn V. O.; Sokolov, Anatoliy N.; Reese, Colin; Bao, Zhenan

2010-10-01

222

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

223

High-sensitivity photoacoustic detection of chemical warfare agents  

NASA Astrophysics Data System (ADS)

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 of these interferences of better than 0.5 ppb in 60 second long measurement time, which satisfies most current homeland and military security requirements and validates the photoacoustic spectroscopy as a powerful technology for nerve gas sensing instrumentation.

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

2004-12-01

224

High sucrose concentration protects E. coli against high pressure inactivation but not against high pressure sensitization to the lactoperoxidase system  

Microsoft Academic Search

The inactivation of Escherichia coli by high hydrostatic pressure treatment at up to 550 MPa and 20 °C was studied in potassium phosphate buffer containing high concentrations of sucrose. E. coli strain MG1655 was pressure-sensitive in the absence of sucrose, but became highly pressure resistant in the presence of 10% to 50% (w\\/v) sucrose. The pressure resistance of E. coli

Isabelle Van Opstal; Suzy C. M. Vanmuysen; Chris W. Michiels

2003-01-01

225

A micro channel integrated gas flow sensor for high sensitivity  

Microsoft Academic Search

In order to enhance measurement accuracy, a gas mass flow sensor integrated with micro channels is proposed in this paper. The uniqueness of this flow sensor is that there is thermal convection effect on two sides of diaphragm, which results in a more sensitive temperature distribution. The temperature characteristics of the novel flow sensor are simulated at different flow rates,

Bolin Yu; Zhiyin Gan; Shu Cao; Jingping Xu; Sheng Liu

2008-01-01

226

New high sensitivity silicon photodetectors for medical imaging applications  

Microsoft Academic Search

We have developed a new silicon photodiode design that reduces the dark current and can improve the sensitivity of low noise silicon photodetector arrays for medical imaging applications. The reduction in dark current eliminates the need for cooling, which facilitates the mechanical design and allows for the optimum performance of the scintillators that are coupled to the photodiodes. The photodetectors

C. R. Tull; J. S. Iwanczyk; B. E. Patt; G. Vilkelis; V. Eremin; E. Verbitskaya; N. Strokan; I. Il'Yashenko; A. Ivanov; A. Sidorov; N. Egorov; S. Golubkov; K. Kon'kov

2003-01-01

227

Uncertainty and sensitivity analysis in high speed device modeling  

Microsoft Academic Search

The simulated annealing (SA) algorithm is extended to extract uncertainty and sensitivity information from the equivalent circuit modeling process. This information is obtained from the probabilistic space exploration process applied in SA. The results obtained from modeling a novel collector-up heterojunction bipolar transistor (HBT) are presented

M.-K. Vai; Ying Chen; Sheila Prasad; Bahman Meskoob; Ceyhun Bulutay

1991-01-01

228

Coomassie blue staining for high sensitivity gel-based proteomics.  

PubMed

Gel electrophoresis, particularly one- (1DE) and two-dimensional electrophoresis (2DE), remain among the most widely used top-down methods for resolving and analysing proteomes. Detection of the resulting protein maps relies on staining (i.e. colloidal coomassie blue (CCB) or SYPRO Ruby (SR), in addition to many others). Fluorescent in-gel protein stains are generally preferred for higher sensitivity, reduced background, and wider dynamic range. Although traditionally used for densitometry, CBB has fluorescent properties. Indeed, infrared detection of CCB stained protein was comparable to SR, with BioSafe (Bio-Rad) and the Neuhoff formulation (NCCB) identified as potentially superior to SR; a minor sensitivity issue encountered in gel-resolved proteomes; might have been due to the unified staining protocol used. Here the staining protocol for both CCB formulations was optimised, yielding improved selectivity without affecting sensitivity; the resulting linear dynamic range was similar for BioSafe and NCCB and somewhat better than SR. 2D gel-based analyses of mouse brain and Arabidopsis thaliana (leaf) proteomes indicated markedly superior spot detection using the NCCB formulation. Thus more sensitive, quantitative in-gel protein analyses can be achieved using NCCB, at a fraction of the cost. This article is part of a Special Issue entitled: From Genome to Proteome: Open Innovations. PMID:23428344

Gauci, Victoria J; Padula, Matthew P; Coorssen, Jens R

2013-02-08

229

Development of a high sensitivity anhydride hexafluorhydric acid sensor  

Microsoft Academic Search

This paper presents theoretical and experimental developments for the implementation of SAW sensors able to detect small concentration of anhydride HF acid in air. Solutions based on the used of surface transverse waves (STW) on quartz (YXlt)\\/36°\\/90° have been analysed to evaluate their potential sensitivity to HF. Devices have been first tested in a BHF solution to identify the kinetics

S. Ballandras; M. H. Nadal; W. Daniau; V. Blondeau-Patissier; G. Martin; G. Lengaigne; V. Eyraud; D. Hauden; B. Guichardaz; L. Hairault; B. Lebret; P. Blind

2003-01-01

230

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

231

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

232

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

233

Highly sensitive differential phase-sensitive surface plasmon resonance biosensor based on the Mach-Zehnder configuration  

Microsoft Academic Search

A high-sensitivity surface plasmon resonance (SPR) biosensor based on the Mach-Zehnder interferometer design is presented. The novel feature of the new design is the use of a Wollaston prism through which the phase quantities of the p and s polarizations are interrogated simultaneously. Since SPR affects only the p polarization, the signal due to the s polarization can be used

S. Y. Wu; H. P. Ho; W. C. Law; Chinlon Lin; S. K. Kong

2004-01-01

234

Comparison of high-frequency quartz crystal microbalances' (QCMs') mass sensitivities to theory  

Microsoft Academic Search

There is a current need for a sensor which can measure minute outgassing or erosion over very long time spans in the space environment. One way of addressing this need is a QCM with very stable output and high mass sensitivity. In order to increase the mass sensitivity. In order to increase the mass sensitivity of the QCM, the crystal

Donald A. Wallace; Scott A. Wallace; Bob E. Wood

1998-01-01

235

Genetic influence on brain catecholamines: high brain norepinephrine in salt-sensitive rats  

SciTech Connect

Rats genetically sensitive to salt-induced hypertension evinced higher levels of plasma norepinephrine and epinephrine than rats genetically resistant to hypertension. The hypertension-sensitive rats showed higher hypothalamic norepinephrine and lower epinephrine than resistant rats. In response to a high salt diet, brain stem norepinephrine increased in sensitive rats while resistant rats exhibited a decrease on the same diet.

Iwai, J; Friedman, R; Tassinari, L

1980-01-01

236

High Sensitive Precise 3D Accelerometer for Solar System Exploration with Unmanned Spacecrafts  

Microsoft Academic Search

Solutions of several space and geophysical tasks require creating high sensitive precise accelerometers with sensitivity in order of 10 -13 g. These several tasks are following: inertial navigation of the Earth and Space; gravimetry nearby the Earth and into Space; geology; geophysics; seismology etc. Accelerometers (gravimeters and gradientmeters) with required sensitivity are not available now. The best accelerometers in the

Y. V. Savenko; P. O. Demyanenko; Y. F. Zinkovskiy

2004-01-01

237

Enhanced Laboratory Sensitivity to Variation of the Fine-Structure Constant using Highly Charged Ions  

Microsoft Academic Search

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

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

2010-01-01

238

Enhanced Laboratory Sensitivity to Variation of the Fine-Structure Constant using Highly Charged Ions  

Microsoft Academic Search

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 alpha. 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

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

2010-01-01

239

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

2013-05-08

240

High-sensitivity silicon photonic biosensors based on cascaded resonators  

NASA Astrophysics Data System (ADS)

Silicon photonic biosensors based on cascaded resonators employing the Vernier effect are shown to be capable of greatly increasing the sensitivity. Two implementation schemes are presented, one using two cascaded ring resonators with a broadband light source, and the other by cascading a Fabry-Perot laser with a silicon ring resonator. Simple intensity interrogation schemes are developed to advance the planar waveguide sensor technology towards low-cost practical applications.

Jiang, Xianxin; Song, Jinyan; Jin, Lei; He, Jian-Jun

2012-11-01

241

Low frequency, high sensitive tunable mechanical monolithic horizontal sensors  

NASA Astrophysics Data System (ADS)

This paper describes an optimized version of the mechanical version of the monolithic tunable folded pendulum, developed at the University of Salerno, configurable both as seismometer and, in a force-feedback configuration, as accelerometer. Typical application of the sensors are in the field of geophysics, including the study of seismic and newtonian noise for characterization of suitable sites for underground interferometer for gravitational waves detection. The sensor, shaped with precision machining and electric-discharge-machining, like the previous version, is a very compact instrument, very sensitive in the low-frequency seismic noise band, with a very good immunity to environmental noises. Important characteristics are the tunability of the resonance frequency and the integrated laser optical readout, consisting of an optical lever and an interferometer. The theoretical sensitivity curves, largely improved due to a new design of the pendulum arms and of the electronics, are in a very good agreement with the measurements. The very large measurement band (10-6 +/- 10Hz) is couple to a very good sensitivity (10-12 m/?Hz in the band 0.1 +/- 10Hz), as seismometer. Prototypes of monolithic seismometers are already operational in selected sites around the world both to acquire seismic data for scientific analysis of seismic noise and to collect all the useful information to understand their performances in the very low frequency band (f < 1mHz). The results of the monolithic sensor as accelerometer (force feed-back configuration) are also presented and discussed. Particular relevance has their sensitivity that is better than 10-11 m/s2/?Hz in the band 0.1 +/- 10Hz. Finally, hypotheses are made on further developments and improvements of monolithic sensors.

Acernese, Fausto; de Rosa, Rosario; Giordano, Gerardo; Romano, Rocco; Vilasi, Silvia; Barone, Fabrizio

2011-03-01

242

ASIC for High Rate 3D Position Sensitive Detectors  

Microsoft Academic Search

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.

Emerson Vernon; Kim Ackley; Gianluigi De Geronimo; Jack Fried; Zhong He; Cedric Herman; Feng Zhang

2010-01-01

243

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

244

Highly sensitive alkane odour sensors based on functionalised gold nanoparticles  

Microsoft Academic Search

We deposit dense, ordered, thin films of Au–dodecanethiol core\\/shell nanoparticles by the Langmuir–Schäfer (LS) printing method, and find that their resistance at ambient temperature responds selectively and sensitively to alkane odours. Response is a rapid resistance increase due to swelling, and is strongest for alkane odours where the alkane chain is similar in length to the dodecane shell. For decane

Hadi AlQahtani; Mark Sugden; Delia Puzzovio; Lee Hague; Nic Mullin; Tim Richardson; Martin Grell

245

High-sensitivity diamond magnetometer with nanoscale resolution  

Microsoft Academic Search

We will discuss our recent work on using isolated electronic spins in the solid-state as sensitive magnetic sensors [1,2]. This novel approach to magnetometry is enabled by the good coherence properties of electronic qubits, such as the spins associated with Nitrogen-Vacancy (NV) centers in diamond, as well as by advanced techniques for their coherent control. The key feature of this

Paola Cappellaro

2009-01-01

246

High-sensitivity damage detection based on enhanced nonlinear dynamics  

NASA Astrophysics Data System (ADS)

One of the most important aspects of detecting damage in the framework of structural health monitoring is increasing the sensitivity of the monitored feature to the presence, location, and extent of damage. Distinct from previous techniques of obtaining information about the monitored structure—such as measuring frequency response functions—the approach proposed herein is based on an active interrogation of the system. This interrogation approach allows for the embedding of the monitored system within a larger system by means of a nonlinear feedback excitation. The dynamics of the larger system is then analyzed in state space, and the shape of the attractor of its dynamics is used as a complex geometric feature which is very sensitive to damage. The proposed approach is implemented for monitoring the structural integrity of a panel forced by transverse loads and undergoing limit cycle oscillations and chaos. The nonlinear von Karman plate theory is used to obtain a model for the panel combined with a nonlinear feedback excitation. The presence of damage is modeled as loss of stiffness of various levels in a portion of the plate at various locations. The sensitivity of the proposed approach to parametric changes is shown to be an effective tool in detecting damages. An earlier version was presented at the SPIE 11th International Symposium on Smart Structures and Materials.

Epureanu, Bogdan I.; Yin, Shih-Hsun; Derriso, Mark M.

2005-04-01

247

High-sensitivity damage detection based on enhanced nonlinear dynamics  

NASA Astrophysics Data System (ADS)

One of the most important aspects of detecting damage in the work-frame of structural health monitoring is increasing the sensitivity of the monitored feature to the presence, location, and extent of damage. Distinct from previous techniques of obtaining information about the monitored structure - such as measuring frequency response functions - the approach proposed herein is based on an active interrogation of the system. This interrogation approach allows for the embedding of the monitored system within a larger system by means of a nonlinear feedback excitation. The dynamics of the larger system is then analyzed in state space, and the shape of the attractor of its dynamics is used as a complex geometric feature which is very sensitive to damage. The proposed approach is implemented for monitoring the structural integrity of a panel forced by transverse loads and undergoing limit cycle oscillations and chaos. The nonlinear von Karman plate theory is used to obtain a model for the panel combined with a nonlinear feedback excitation. The presence of damage is modeled as a loss of stiffness in a portion of the plate. The sensitivity of the proposed approach to parametric changes is shown to be an effective tool in detecting damages.

Epureanu, Bogdan I.; Yin, Shih-Hsun; Derriso, Mark M.

2004-07-01

248

High Resolution, High Sensitivity Detectors for Molecular Imaging of Small Animals and Tumor Detection  

NASA Astrophysics Data System (ADS)

Imaging techniques with radionuclides provide very sensitive measures of a wide range of specific processes underying disease in the body. Detection of very small tumors with high specificity is therefore possible but the tecnique requires both high spatial resolution and high sensitivity. We present the first simulations, performed by means of GEANT4 code, of breast tumors, imaged by different configurations of a compact discrete gamma camera, in order to optimize the performances of dedicated detectors for these tasks. Simulated planar images from 6 to 10 mm diameter tumors, placed at 5 mm from the collimator, were generated for NaI scintillator pixel sizes of 1.0×1.0 and 1.2×1.2 mm2, hexagonal hole Pb collimators with hole size of 1.5 and 1.9 mm. The generated photons have been sampled by two modelled Hamamatsu H8500 and H9500 PMT. Tumor to background uptake ratio from 1:6 to 1:12 has been considered. The preliminary results in terms of spatial resolution and SNR show a slightly better performance of the high efficiency collimator, larger crystal size and H9500 combination.

Magliozzi, M. L.; Cisbani, E.; Colilli, S.; Cusanno, F.; Fratoni, R.; Garibaldi, F.; Giuliani, F.; Gricia, M.; Lo Meo, S.; Lucentini, M.; Santavenere, F.; Veneroni, P.; Schillaci, O.; Simonetti, G.; Majewsky, S.; Cinti, M. N.; de Vincentis, G.; Pani, R.; Pellegrini, R.; Scopinaro, F.

2006-04-01

249

ANNINE-6plus, a voltage-sensitive dye with good solubility, strong membrane binding and high sensitivity  

Microsoft Academic Search

We present a novel voltage-sensitive hemicyanine dye ANNINE-6plus and describe its synthesis, its properties and its voltage-sensitivity\\u000a in neurons. The dye ANNINE-6plus is a salt with a double positively charged chromophore and two bromide counterions. It is\\u000a derived from the zwitterionic dye ANNINE-6. While ANNINE-6 is insoluble in water, ANNINE-6plus exhibits a high solubility\\u000a of around 1 mM. Nonetheless, it displays

Peter Fromherz; Gerd Hübener; Bernd Kuhn; Marlon J. Hinner

2008-01-01

250

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

251

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

252

High-sensitivity, high-selectivity detection of chemical warfare agents  

NASA Astrophysics Data System (ADS)

We report high-sensitivity detection of chemical warfare agents (nerve gases) with very low probability of false positives (PFP). We demonstrate a detection threshold of 1.2 ppb (7.7 ?g/m3 equivalent of Sarin) with a PFP of <1:106 in the presence of many interfering gases present in an urban environment through the detection of diisopropyl methylphosphonate, an accepted relatively harmless surrogate for the nerve agents. For the current measurement time of ~60 s, a PFP of 1:106 corresponds to one false alarm approximately every 23 months. The demonstrated performance satisfies most current homeland and military security requirements.

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

2006-01-01

253

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

254

A protein multiplex microarray substrate with high sensitivity and specificity  

PubMed Central

The problems that have been associated with protein multiplex microarray immunoassay substrates and existing technology platforms include: binding, sensitivity, a low signal to noise ratio, target immobilization and the optimal simultaneous detection of diverse protein targets. Current commercial substrates for planar multiplex microarrays rely on protein attachment chemistries that range from covalent attachment to affinity ligand capture, to simple adsorption. In this pilot study, experimental performance parameters for direct monoclonal mouse IgG detection were compared for available two and three dimensional slide surface coatings with a new colloidal nitrocellulose substrate. New technology multiplex microarrays were also developed and evaluated for the detection of pathogen specific antibodies in human serum and the direct detection of enteric viral antigens. Data supports the nitrocellulose colloid as an effective reagent with the capacity to immobilize sufficient diverse protein target quantities for increased specificory signal without compromising authentic protein structure. The nitrocellulose colloid reagent is compatible with the array spotters and scanners routinely used for microarray preparation and processing. More importantly, as an alternate to fluorescence, colorimetric chemistries may be used for specific and sensitive protein target detection. The advantages of the nitrocellulose colloid platform indicate that this technology may be a valuable tool for the further development and expansion of multiplex microarray immunoassays in both the clinical and research laborat environment.

Fici, Dolores A.; McCormick, William; Brown, David W.; Herrmann, John E.; Kumar, Vikram; Awdeh, Zuheir L.

2010-01-01

255

A protein multiplex microarray substrate with high sensitivity and specificity.  

PubMed

The problems that have been associated with protein multiplex microarray immunoassay substrates and existing technology platforms include: binding, sensitivity, a low signal to noise ratio, target immobilization and the optimal simultaneous detection of diverse protein targets. Current commercial substrates for planar multiplex microarrays rely on protein attachment chemistries that range from covalent attachment to affinity ligand capture, to simple adsorption. In this pilot study, experimental performance parameters for direct monoclonal mouse IgG detection were compared for available two and three-dimensional slide surface coatings with a new colloidal nitrocellulose substrate. New technology multiplex microarrays were also developed and evaluated for the detection of pathogen-specific antibodies in human serum and the direct detection of enteric viral antigens. Data supports the nitrocellulose colloid as an effective reagent with the capacity to immobilize sufficient diverse protein target quantities for increased specific signal without compromising authentic protein structure. The nitrocellulose colloid reagent is compatible with the array spotters and scanners routinely used for microarray preparation and processing. More importantly, as an alternate to fluorescence, colorimetric chemistries may be used for specific and sensitive protein target detection. The advantages of the nitrocellulose colloid platform indicate that this technology may be a valuable tool for the further development and expansion of multiplex microarray immunoassays in both the clinical and research laboratory environment. PMID:20974147

Fici, Dolores A; McCormick, William; Brown, David W; Herrmann, John E; Kumar, Vikram; Awdeh, Zuheir L

2010-10-23

256

High color-vision sensitivity in macaque and humans.  

PubMed

Psychophysical (behavioral) detection thresholds and color-discrimination thresholds were determined in a macaque using a two-alternative forced-choice procedure. On a white background, detection thresholds were determined for a white increment and three spectral increments: 618, 516, and 456 nm. Intermixed with detection threshold determinations, color-discrimination thresholds were determined by presenting the white increment, and one of the spectral increments, at 1.0 log units above their respective detection thresholds and dimming both until discrimination performance fell to threshold. The monkey could discriminate the color of the increments at detection threshold because the average color-discrimination threshold was 0.98+/-0.14 log attenuation. Because the monkey was much more sensitive to the spectral increments than the white increment, we performed an unconventional experiment. We determined the monkey's detection threshold for the white increment alone, and with broadband color filters in the white light path without adjusting the light's intensity. Insertion of several color filters in the light path lowered detection thresholds of both the macaque and six human trichromats. We believe that this improvement in detection thresholds produced by simply inserting color filters in a white light path is a threshold manifestation of the Helmholtz-Kohlrausch effect and suggests that one of color vision's important evolutionary advantages may be improved detection sensitivity. PMID:10750833

Loop, M S; Crossman, D K

257

Highly sensitive urea sensing with ion-irradiated polymer foils  

NASA Astrophysics Data System (ADS)

Recently we prepared urea-sensors by attaching urease to the inner walls of etched ion tracks within thin polymer foil. Here, alternative track-based sensor configurations are examined where the enzyme remained in solution. The conductivities of systems consisting of two parallel irradiated polymer foils and confining different urea/urease mixtures in between were examined. The correlations between conductivity and urea concentration differed strongly for foils with unetched and etched tracks, which points at different sensing mechanisms - tentatively attributed to the adsorption of enzymatic reaction products on the latent track entrances and to the enhanced conductivity of reaction product-filled etched tracks, respectively. All examined systems enable in principle, urea sensing. They point at the possibility of sensor cascade construction for more sensitive or selective sensor systems.

Fink, Dietmar; Muñoz Hernandez, Gerardo; Alfonta, Lital

2012-02-01

258

High Sensitivity PEA System with Dual Polarity Pulse Generator  

NASA Astrophysics Data System (ADS)

The pulsed electroacoustic (PEA) method has been widely used to observe space charge distributions in various solid dielectric materials. The sensitivity of the conventional PEA system is around 1 C/m3. When the charge density is less than 1 C/m3, however, it is difficult to obtain an accurate result because the signal due to the Maxwell stress becomes comparable with the signal to be measured. The Maxwell stress is generated by applying the pulsed electric field to the dielectrics, and independent from the existence of either induced charges by dc bias voltage or internal charges. In order to eliminate the influence of the Maxwell stress, we have developed a new PEA system with a dual polarity pulse generator. The system achieved to measure space charge density around 0.03 C/m3.

Matsui, Kohei; Tanaka, Yasuhiro; Takada, Tatsuo; Fukao, Tadashi; Maeno, Takashi

259

The Efficacy of Habituation in Decreasing Subjective Distress Among High Anxiety-Sensitive College Students  

Microsoft Academic Search

While there is mounting evidence that the concept of anxiety sensitivity (AS) is linked to the expression of anxiety (specifically, panic), there has been little research comparing the efficacy of interoceptive exposure alone with interoceptive exposure coupled with cognitive restructuring among high AS participants. The present investigation addressed this issue in a sample of high anxiety-sensitive college students (scores above

Michele M Carter; Nancy Watt Marin; Karen L Murrell

1999-01-01

260

A highly sensitive and specific system for large-scale gene expression profiling  

Microsoft Academic Search

BACKGROUND: Rapid progress in the field of gene expression-based molecular network integration has generated strong demand on enhancing the sensitivity and data accuracy of experimental systems. To meet the need, a high-throughput gene profiling system of high specificity and sensitivity has been developed. RESULTS: By using specially designed primers, the new system amplifies sequences in neighboring exons separated by big

Guohong Hu; Qifeng Yang; Xiangfeng Cui; Gang Yue; Marco A Azaro; Hui-Yun Wang; Honghua Li

2008-01-01

261

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

262

A high-sensitivity drinkometer circuit with 60Hz filtering  

Microsoft Academic Search

This article describes a drinkometer circuit designed to (1) detect licks even if the resistance of the skin on the animal’s\\u000a feet becomes quite high due to low humidity, (2) automatically adjust its triggering threshold and increase its gain so that\\u000a it will continue to detect licks when the water delivery spout is partially shorted to ground by high ambient

Roger L. Overton; Donald A. Overton

2007-01-01

263

Outcomes of cardiac transplantation in highly sensitized pediatric patients.  

PubMed

Despite aggressive immunosuppressive therapy, pediatric orthotopic heart transplant (OHT) candidates with elevated pre-transplant panel reactive antibody (PRA) carry an increased risk of rejection and early graft failure following transplantation. This study has aimed to more specifically evaluate the outcomes of transplant candidates stratified by PRA values. Records of pediatric patients listed for OHT between April 2004 and July 2008 were reviewed (n = 101). Survival analysis was performed comparing patients with PRA < 25 to those with PRA > 25, as well as patients with PRA < 80 and PRA > 80. Patients with PRA > 25 had decreased survival compared with those with PRA < 25 after listing (P = 0.004). There was an even greater difference in survival between patients with PRA > 80 and those with PRA < 80 (P = 0.002). Similar analyses for the patients who underwent successful transplantation showed no significant difference in post-transplant survival between patients with a pre-transplant PRA > 25 and those with PRA < 25 (P = 0.23). A difference approaching significance was noted for patients with PRA > 80 compared with PRA < 80 (P = 0.066). Patients with significantly elevated pre-transplant PRAs at the time of listing have a significantly worse outcome compared to those with moderately increased PRA values or non-sensitized patients. Further study is necessary to guide physician and family treatment decisions at the time of listing. PMID:21380717

Scott, Victoria; Williams, Ryan J; Levi, Daniel S

2011-03-06

264

High sensitivity capacitive MEMS microphone with spring supported diaphragm  

NASA Astrophysics Data System (ADS)

Capacitive microphones (condenser microphones) work on a principle of variable capacitance and voltage by the movement of its electrically charged diaphragm and back plate in response to sound pressure. There has been considerable research carried out to increase the sensing performance of microphones while reducing their size to cater for various modern applications such as mobile communication and hearing aid devices. This paper reviews the development and current performance of several condenser MEMS microphone designs, and introduces a microphone with spring supported diaphragm to further improve condenser microphone performance. The numerical analysis using Coventor FEM software shows that this new microphone design has a higher mechanical sensitivity compared to the existing edge clamped flat diaphragm condenser MEMS microphone. The spring supported diaphragm is shown to have a flat frequency response up to 7 kHz and more stable under the variations of the diaphragm residual stress. The microphone is designed to be easily fabricated using the existing silicon fabrication technology and the stability against the residual stress increases its reproducibility.

Mohamad, Norizan; Iovenitti, Pio; Vinay, Thurai

2007-12-01

265

High-sensitivity pyroelectric linear arrays and their applications  

NASA Astrophysics Data System (ADS)

Pyroelectric infrared detectors have among other things the known advantages of being able to be used at room temperature and of being provided with a sufficient signal- to-noise ratio for a number of applications, a spectral responsivity of a relative homogeneity within the infrared range, and properties of a very long-term stability. For extending their range of application both extensive and intensive efforts were made, during the last few years, to considerably improve responsivity, noise equivalent power (NEP) and modulation transfer function of linear arrays. The paper describes the structure and the main properties of newly developed line sensors based on lithium tantalate and containing 128 sensitive elements (size of element: 90 X 100 micrometers (superscript 2), pitch 100 micrometers ). It is shown that the thickness of the responsive elements has a strong influence on responsivity. Special techniques for structuring the pyroelectric chip and using a low-noise CMOS read-out circuit made it possible to achieve NEP values below 0.5 nW at a chopper frequency of 40 Hz. Illustrated by the examples of a line scanner and a 2D camera, the paper proves that noise equivalent temperature difference values around 0.1 K are possible.

Norkus, Volkmar; Budzier, Helmut; Sokoll, Torsten; Hofmann, Guenter; Hoffmann, Uwe; Hess, Norbert

1996-06-01

266

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

PubMed

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. PMID:23977083

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

2013-08-19

267

Provably Correct High-level Timing Analysis Without Path Sensitization  

Microsoft Academic Search

This paper addresses the problem of true delay estimation during high level design. The existing delay estimation techniques ei- ther estimate the topological delay of the circuit which may be pes- simistic, or use gate-level timing analysis for calculating the true de- lay, which may be prohibitively expensive. We show that the paths in the implementation of a behavioral spec-

Subhrajit Bhattacharya; Sujit Dey; Franc Brglez

1994-01-01

268

Polycarbonates: a long-term highly sensitive radon monitor  

Microsoft Academic Search

An approach for long-term (either retrospective or prospective) 222Rn measurements is proposed that is based on the combination of the high radon absorption ability of some polycarbonates with their alpha track-etch properties. The detection limit is projected to be <10Bqm?3 for an exposure time of 20yr.

D. Pressyanov; J. Buysse; A. Poffijn; G. Meesen; A Van Deynse

2000-01-01

269

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

270

A high sensitivity long period grating Mach-Zehnder refractometer  

Microsoft Academic Search

A refractive index sensing system has been demonstrated, which is based upon an in-line fibre long period grating Mach-Zehnder interferometer with a heterodyne interrogation technique. This sensing system has comparable accuracy to laboratory-based techniques used in industry such as high performance liquid chromatography and UV spectroscopy. The advantage of this system is that measurements can be made in-situ for applications

T. Allsop; D. J. Webb; I. Bennion

2002-01-01

271

High sensitive and high resolution investigations of the Jovian S-burst emission modulation features  

NASA Astrophysics Data System (ADS)

In spite of the long history of studying, the Jovian S-burst radiation still represents an event which needs to be investigated in detail. Many questions concerning this complex phenomenon are opened. One of the interesting problems is the different modulation features appearing on the dynamic spectra in dependence on the time resolution achieved in the experiment and also on the visualization time scale. It seems that in every concrete case the physical mechanism of the modulation is different. In connection to this the following statistical sets need to be fully collected and analyzed for each modulation effects: 1) observed conditions: dependence or independence on Jupiter - Io - observer position, season time, day-night time, the Solar activity; 2) observed parameters: sign and value of the frequency drift, lane's curvature, modulation depth, distances between the nearest lanes and their variety, scale of the modulation; 3) polarization properties. During the last years the new high sensitive recording facilities, such as the digital spectro-polarimiter (DSP) and waveform receiver (WFR) were created and installed into the largest decameter band antenna array UTR-2 (Kharkov, Ukraine). It can be noted that in the present time this combination (antenna + equipments) gives the best sensitiveness, band of analysis, dynamic range, time and frequency resolutions. The using of mentioned above technique allowed detecting new time-frequency features of the Jovian S-bursts. Several bright new results concerning the modulations were obtained. With the creation of new giant low frequency antenna array (LOFAR) and low wavelength array (LWA) the new possibilities of high level study of the Jovian DAM emission will appear. For instance, the combination of LOFAR and already existing instruments (max base in order of 2000 km) will permit to determine the spatial parameters and localization of an emission source. Future results may prove useful for the general understanding of the still unclear origin of the sporadic Jovian decametre emission.

Litvinenko, G. V.; Konovalenko, A. A.; Rucker, H. O.; Lecacheux, A.; Vinogradov, V. V.

2007-08-01

272

A Highly Sensitive, High-Throughput Assay for the Detection of Turner Syndrome  

PubMed Central

Objective: Turner syndrome (TS) occurs when an X-chromosome is completely or partially deleted or when X-chromosomal mosaicism is present. Girls with TS benefit from early diagnosis and treatment with GH; however, many girls with TS are not detected until after 10 yr of age, resulting in delayed evaluation and treatment. Methods: We developed a high-throughput test for TS, based on a quantitative method of genotyping to detect X-chromosome abnormalities. This test uses pyrosequencing to quantitate relative allele strength (RAS) from single-nucleotide polymorphisms using 18 informative single-nucleotide polymorphisms markers that span the X-chromosome and one marker for the detection of Y-chromosome material. Results: Cutoff ranges for heterozygous, homozygous, or out-of-range RAS values were established from a cohort of 496 males and females. Positive TS scoring criteria were defined as the presence of homozygosity for all 18 markers or the presence of at least one out-of-range RAS value. To determine the validity of this rapid test for TS detection, we undertook a large-scale study using DNA from 132 females without TS and 74 females with TS for whom karyotypes were available. TS was identified with 96.0% sensitivity and 97.0% specificity in this cohort. We also tested buccal swab DNA from a group of 19 females without TS and 69 females with TS. In this group, TS was identified with 97.1% sensitivity and 84.2% specificity. Conclusions: These results demonstrate the validity of a high-throughput, pyrosequencing based test for the accurate detection of TS, providing a potential alternative to karyotype testing.

Hager, Karl; Hosono, Seiyu; Wise, Anastasia; Li, Peining; Rinder, Henry M.; Gruen, Jeffrey R.

2011-01-01

273

First experiences with a high sensitive videocamera with internal multiframe exposure time  

NASA Astrophysics Data System (ADS)

This is a short report about the use of the high sensitive black-white video camera MTV-12V1-EX that allows to increase the sensitivity about 2 magnitudes in normal video mode and about 4 magnitudes by using the internal selectable multiframe exposure time with 0.3 sec time resolution (compared with sensitivity of simple black-white video cameras). A video record demonstrates some occultation events and starfields.

Rothe, Wolfgang

2002-07-01

274

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

Microsoft Academic Search

We study atomic systems that are in the frequency range of optical atomic\\u000aclocks and have enhanced sensitivity to potential time-variation of the fine\\u000astructure constant, alpha. The high sensitivity is due to coherent\\u000acontributions from three factors: high nuclear charge Z, high ionization\\u000adegree, and significant differences in the configuration composition of the\\u000astates involved. Configuration crossing keeps the

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

2010-01-01

275

Fabrication of high sensitivity ZnO thin film ultrasonic devices by electrochemical etch techniques  

Microsoft Academic Search

In this experiment, high quality thin film acoustic devices were constructed utilizing zinc oxide (ZnO) thin film deposition, integrated circuit (IC), and electrochemical etch techniques. The bridge type ZnO thin film ultrasonic devices produced showed acute high frequency response sensitivity, with the high frequency response at 600 KHz attaining -124 dBV ?Bar. The highest response was near 8 MHz. Sensitivity

Chung C. Chang; Young E. Chen

1997-01-01

276

Single-photon camera for high-sensitivity high-speed applications  

NASA Astrophysics Data System (ADS)

We present a high-speed Single-Photon Camera for demanding applications in biology, astrophysics, telecommunications, 3D imaging and security surveillance. The camera is based on a 32-by-32 array of "smart pixels" processed in a standard high-voltage technology. Every pixel is a completely independent photon-counting channel. Sensitivity is at the single-photon level and no readout noises affect the measure. The camera has high Photon-Detection Efficiency (PDE) in the blu/green visible spectrum (45% at 450 nm) and low Dark-Counting Rate (DCR) even at room temperature (usually lower than 2 kcps). The use of microlenses makes it possible to further increase the effective pixel fill-factor. The camera can be configured by means of a cross-platform user-friendly software that communicates with the camera through a fast USB link. The integration time window may range from few tens of nanoseconds to milliseconds. The maximum frame rate for the whole 1,024 pixels is about 100 kframe/s, while the minimum 20 ns dead-time between frames boosts the sensor dynamic range. The camera is equipped with a standard C-Mount connector. A gating input pin can be used to quickly gate on/off the integration. The camera works in One-Shot mode for the maximum acquisition speed, Real-Time mode for very long measurements and Live mode for setups alignment purposes.

Guerrieri, Fabrizio; Tisa, Simone; Tosi, Alberto; Zappa, Franco

2010-02-01

277

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

278

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

279

Porous tungsten oxide nanoflakes for highly alcohol sensitive performance.  

PubMed

Porous tungsten oxide (WO(3)) nanoflakes have been synthesized by a simple and green approach in an ambient environment. As a precursor solution a polycrystalline hydrated tungstite (H(2)WO(4)·H(2)O) nanoparticles colloid was first prepared by pulsed-laser ablation of a tungsten target in water. The H(2)WO(4)·H(2)O nanoflakes were produced by 72 h aging treatment at room temperature. Finally, porous WO(3) nanoflakes were synthesized by annealing at 800 °C for 4 h. Considering the large surface-to-volume ratio of porous nanoflakes, a porous WO(3) 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. PMID:23069859

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

2012-11-21

280

Enhanced Laboratory Sensitivity to Variation of the Fine-Structure Constant using Highly Charged Ions  

NASA Astrophysics Data System (ADS)

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.

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

2010-09-01

281

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

282

Ultra-high resolution optical trap with single fluorophore sensitivity  

NASA Astrophysics Data System (ADS)

We present a new single-molecule instrument that combines ultra- high resolution optical tweezers with single-fluorophore fluorescence microscopy. 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). The optical tweezers portion of the instrument is based on a timeshared dual optical trap design and is interlaced with a confocal fluorescence microscope. In a demonstration experiment, individual single-fluorophore labeled DNA oligonucleotides can be 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 can be clearly observed.

Chemla, Yann

2011-03-01

283

High sensitivity alpha-particle and electron spectroscopy  

NASA Astrophysics Data System (ADS)

Thin massless sources of 238Pu and 249Cf, prepared in an electromagnetic isotope separator, have been used to determine the characteristics of newly developed passivated ion implanted silicon detectors. These detectors are found to be superior to the usual Au-Si surface barrier detectors, both in resolution and peak tailing. For 238Pu ?-groups we have measured a resolution (fwhm) of (9.2 +/- 0.2) keV and find the tail to be 1.0 × 10-5 of the peak height. This tailing is more than an order of magnitude better than that obtained with the best surface barrier detectors. Relative intensities of 249Cf ?-groups have also been measured with high precision.

Ahmad, Irshad

1986-01-01

284

A highly sensitive and selective fluorescent chemosensor for Pb2+ ions in an aqueous solution.  

PubMed

A new fluorescent sensor based on the BODIPY fluorophore and the polyamide receptor for Pb(2+) was designed and synthesized. The sensor is highly selective for Pb(2+) over relevant competing metal ions, and sensitive to ppb levels of Pb(2+). It features the most sensitive probe to date for Pb(2+) ions in water. PMID:23319008

Liu, Jing; Wu, Kai; Li, Sha; Song, Tao; Han, Yifeng; Li, Xin

2013-01-14

285

A high- trans fatty acid diet and insulin sensitivity in young healthy women  

Microsoft Academic Search

Epidemiological and experimental studies suggest that a diet rich in saturated fat affects insulin sensitivity. Monoenes and dienes that have an usaturated bond with the trans configuration (trans fatty acids) resemble saturated fatty acids with respect to structure, but no published data are available on the effect of trans fatty acids on insulin sensitivity. Therefore, the effects of diets high

Anne M. Louheranta; Anu K. Turpeinen; Helvi M. Vidgren; Ursula S. Schwab; Matti I. J. Uusitupa

1999-01-01

286

MEMS approach for making a low cost, high sensitivity magnetic sensor  

Microsoft Academic Search

An approach based on electromechanical systems (MEMS) technology will be presented that essentially eliminates the problem of 1\\/f noise in small magnetic sensors. The sensor based on this approach, the MEMS flux concentrator sensor, should outperform all other high sensitivity vector magnetometers in terms of cost, power consumption, and sensitivity. The method for achieving this improvement is to employ flux

A. S. Edelstein; G. A. Fischer; W. Egelhoff; J. E. Burnette

2010-01-01

287

Differential sensitivity of long-sleep and short-sleep mice to high doses of cocaine.  

PubMed

The cocaine sensitivity of male and female long-sleep (LS) and short-sleep (SS) mice, which have been selectively bred for differential ethanol-induced "sleep-time," was examined in a battery of behavioral and physiological tests. Differences between these two mouse lines were subtle and were seen primarily at high doses. At high doses, SS mice were more sensitive than LS mice, particularly to cocaine-induced hypothermia; however, significant hypothermia was not seen except at doses which were very near to the seizure threshold. During a 60-min test of locomotor activity, LS mice showed greater stimulation of Y-maze activity by 20 mg/kg cocaine than SS mice. Consistent with the finding of subtle differences in sensitivity to low doses of cocaine. LS and SS mice did not differ in sensitivity to cocaine inhibition of synaptosomal uptake of [3H]-dopamine, [3H]-norepinephrine or [3H]-5-hydroxytryptamine. However, consistent with the finding of differential sensitivity to high doses of cocaine, SS mice were more sensitive to the seizure-producing effects of the cocaine and lidocaine, a local anesthetic. It is hypothesized that the differential sensitivity of these mouse lines to high doses of cocaine is due to differential sensitivity to cocaine's actions on systems that regulate local anesthetic effects. Selective breeding for differential duration of alcohol-induced "sleep-time" may have resulted in differential ion channel structure or function in these mice. PMID:2623042

de Fiebre, C M; Ruth, J A; Collins, A C

1989-12-01

288

Resolution in quartz crystal oscillator circuits for high sensitivity microbalance sensors in damping media  

Microsoft Academic Search

The use of quartz crystal oscillators as high sensitivity microbalance sensors is limited by the frequency noise present in the circuit. To characterise the behaviour of the sensors, it is not enough to determine their experimental sensitivity, but rather it is essential to study the frequency fluctuations in order to establish the sensor resolution. This is fundamental in the case

L. Rodriguez-Pardo; J. Fariña; C. Gabrielli; H. Perrot; R. Brendel

2004-01-01

289

Equilibrium temperature profiles in highly sensitive tubular reactors  

SciTech Connect

The authors consider a highly exothermic reaction being carried out in a long tubular fixed-bed reactor, whose walls are maintained at a fixed temperature T/sub c/ by external cooling. To maintain control of these reactions and avoid reactor runaways, such reactors must be designed so that their temperature rises ..delta..T are small fractions of the adiabatic temperature rise ..delta..T/sub ad/, the rise which would occur if the reactor was insulated. However, ..delta..T/..delta..T/sub ad/<< 1 can only occur if eta identical to t/sub dif//t/sub reac/ << 1, where t/sub dif/ is the timescale on which heat escapes the reactor by diffusing radially to the cool reactor walls and t/sub reac/ is the reaction timescale. Here they exploit eta << 1 to reduce the reactor equations to T/sub s/ = delta/sup 2/T + QR(X, T), 0high temperatures. Finally, the domain-of-attraction results enable us to conclude that the reactor will operate stably according to the bottom branch of solutions if T/sub c/ < T/sub c//sup cr/, and that reactor runaway occurs if T/sub c/ > T/sub c//sup cr/ where T/sub c//sup cr/ is the turning point of the bottom solution branch.

Hagan, P.S.; Herskowitz, M.; Pirkle, C.

1987-12-01

290

Phenomenally high molar extinction coefficient sensitizer with "donor-acceptor" ligands for dye-sensitized solar cell applications.  

PubMed

A phenomenally high molar extinction coefficient heteroleptic ruthenium(II) complex [Ru(4,4'-carboxylic acid-2,2'-bipyridine)(4,4'-(4-{4-methyl-2,5-bis[3-methylbutoxy]styryl}-2,5-bis[3-methylbutoxy]-2,2'-bipyridine)(NCS) 2] ( DCSC13) was synthesized by incorporating donor-acceptor ligands. The absorption spectrum of the DCSC13 sensitizer is dominated by metal-to-ligand charge-transfer transitions (MLCT) in the visible region, with absorption maxima appearing at 442 and 554 nm. The lowest MLCT absorption bands are red-shifted, and the molar extinction coefficients of these bands are significantly higher at 72,100 and 30,600 M(-1) cm(-1), respectively, when compared to those of the analogous [Ru(4,4'-carboxylic acid-2,2'-bipyridine)(4,4'-dimethyl-2,2'-bipyridine)(NCS)2] (N820) sensitizer. The DCSC13 complex, when anchored on nanocrystalline TiO 2 films, exhibited increased short-circuit photocurrent and consequent power-conversion efficiency when compared with the N820 sensitizer. PMID:17824603

Lee, Chongchan; Yum, Jun-Ho; Choi, Hyunbong; Ook Kang, Sang; Ko, Jaejung; Humphry-Baker, Robin; Grätzel, Michael; Nazeeruddin, Md K

2007-09-07

291

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

292

Confidence Level and Sensitivity Limits in High Contrast Imaging  

SciTech Connect

In long adaptive optics corrected exposures, exoplanet detections are currently limited by speckle noise originating from the telescope and instrument optics, and it is expected that such noise will also limit future high-contrast imaging instruments for both ground and space-based telescopes. Previous theoretical analysis have shown that the time intensity variations of a single speckle follows a modified Rician. It is first demonstrated here that for a circular pupil this temporal intensity distribution also represents the speckle spatial intensity distribution at a fix separation from the point spread function center; this fact is demonstrated using numerical simulations for coronagraphic and non-coronagraphic data. The real statistical distribution of the noise needs to be taken into account explicitly when selecting a detection threshold appropriate for some desired confidence level. In this paper, a technique is described to obtain the pixel intensity distribution of an image and its corresponding confidence level as a function of the detection threshold. Using numerical simulations, it is shown that in the presence of speckles noise, a detection threshold up to three times higher is required to obtain a confidence level equivalent to that at 5{sigma} for Gaussian noise. The technique is then tested using TRIDENT CFHT and angular differential imaging NIRI Gemini adaptive optics data. It is found that the angular differential imaging technique produces quasi-Gaussian residuals, a remarkable result compared to classical adaptive optic imaging. A power-law is finally derived to predict the 1-3 x 10{sup -7} confidence level detection threshold when averaging a partially correlated non-Gaussian noise.

Marois, C

2007-11-07

293

Confidence Level and Sensitivity Limits in High Contrast Imaging  

SciTech Connect

In long adaptive optics corrected exposures, exoplanet detections are currently limited by speckle noise originating from the telescope and instrument optics, and it is expected that such noise will also limit future high-contrast imaging instruments for both ground and space-based telescopes. Previous theoretical analysis have shown that the time intensity variations of a single speckle follows a modified Rician. It is first demonstrated here that for a circular pupil this temporal intensity distribution also represents the speckle spatial intensity distribution at a fix separation from the point spread function center; this fact is demonstrated using numerical simulations for coronagraphic and non-coronagraphic data. The real statistical distribution of the noise needs to be taken into account explicitly when selecting a detection threshold appropriate for some desired confidence level. In this paper, a technique is described to obtain the pixel intensity distribution of an image and its corresponding confidence level as a function of the detection threshold. Using numerical simulations, it is shown that in the presence of speckles noise, a detection threshold up to three times higher is required to obtain a confidence level equivalent to that at 5{sigma} for Gaussian noise. The technique is then tested using TRIDENT CFHT and angular differential imaging NIRI Gemini adaptive optics data. It is found that the angular differential imaging technique produces quasi-Gaussian residuals, a remarkable result compared to classical adaptive optic imaging. A power-law is finally derived to predict the 1-3 x 10{sup -7} confidence level detection threshold when averaging a partially correlated non-Gaussian noise.

Marois, C; LaFreniere, D; Macintosh, B; Doyon, R

2008-06-02

294

Confidence Level and Sensitivity Limits in High-Contrast Imaging  

NASA Astrophysics Data System (ADS)

In long adaptive optics corrected exposures, exoplanet detections are currently limited by speckle noise originating from the telescope and instrument optics, and it is expected that such noise will also limit future high-contrast imaging instruments for both ground- and space-based telescopes. Previous theoretical analyses have shown that the time intensity variations of a single speckle follow a modified Rician. It is first demonstrated here that for a circular pupil, this temporal intensity distribution also represents the speckle spatial intensity distribution at a fixed separation from the point-spread function center; this fact is demonstrated using numerical simulations for coronagraphic and noncoronagraphic data. The real statistical distribution of the noise needs to be taken into account explicitly when selecting a detection threshold appropriate for some desired confidence level (CL). In this paper, a technique is described to obtain the pixel intensity distribution of an image and its corresponding CL as a function of the detection threshold. Using numerical simulations, it is shown that in the presence of speckle noise, a detection threshold up to 3 times higher is required to obtain a CL equivalent to that at 5 ? for Gaussian noise. The technique is then tested on data acquired by simultaneous spectral differential imaging with TRIDENT and by angular differential imaging with NIRI. It is found that the angular differential imaging technique produces quasi-Gaussian residuals, a remarkable result compared to classical adaptive optic imaging. Finally, a power law is derived to predict the 1-3×10-7 CL detection threshold when averaging a partially correlated non-Gaussian noise. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. Also based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina).

Marois, Christian; Lafrenière, David; Macintosh, Bruce; Doyon, René

2008-01-01

295

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...

296

Quartz Crystal Microbalance Based System for High-Sensitivity Differential Sputter Yield Measurements (Preprint).  

National Technical Information Service (NTIS)

We present a quartz crystal microbalance (QCM) based system for high sensitivity differential sputter yield measurements of different target materials due to ion bombardment. The differential sputter yields can be integrated to find total yields. Possible...

A. P. Yalin B. Rubin C. C. Farnell J. L. Topper

2009-01-01

297

Development of a 300,000-pixel ultrahigh-speed high-sensitivity CCD  

NASA Astrophysics Data System (ADS)

We are developing an ultrahigh-speed, high-sensitivity broadcast camera that is capable of capturing clear, smooth slow-motion videos even where lighting is limited, such as at professional baseball games played at night. In earlier work, we developed an ultrahigh-speed broadcast color camera1) using three 80,000-pixel ultrahigh-speed, highsensitivity CCDs2). This camera had about ten times the sensitivity of standard high-speed cameras, and enabled an entirely new style of presentation for sports broadcasts and science programs. Most notably, increasing the pixel count is crucially important for applying ultrahigh-speed, high-sensitivity CCDs to HDTV broadcasting. This paper provides a summary of our experimental development aimed at improving the resolution of CCD even further: a new ultrahigh-speed high-sensitivity CCD that increases the pixel count four-fold to 300,000 pixels.

Ohtake, H.; Hayashida, T.; Kitamura, K.; Arai, T.; Yonai, J.; Tanioka, K.; Maruyama, H.; Etoh, T. Goji; Poggemann, D.; Ruckelshausen, A.; van Kuijk, H.; Bosiers, Jan T.

2006-03-01

298

Sensitization of high-nitrogen austenitic stainless steels by dichromium nitride precipitation  

SciTech Connect

High-nitrogen (N) stainless steels (SS) are receiving increased attention because of their strength advantages over carbon (C)-alloyed materials, but they have been found susceptible to dichromium nitride (Cr[sub 2]N) precipitation during thermal exposure between [approximately]600 C and 1,050 C. Sensitization susceptibility of a high-N, low-C austenitic SS by Cr[sub 2]N precipitation at 700 C and 900 C was determined using the single-loop electrochemical potentiokinetic reactivation (EPR) test. High-N SS was found susceptible to sensitization caused by grain boundary (GB) precipitation of Cr[sub 2]N, with the degree of sensitization increasing systematically with aging time at 700 C. Sensitization of high-N materials did not require the concomitant precipitation of chromium (Cr)-rich metal carbide (M[sub 23]C[sub 6]). Materials aged at 900 C were not sensitized, although the rate of precipitation was greater than at 700 C. This indicated the minimum Cr level in the Cr-depleted zone of the matrix associated with nitride precipitation at 900 C was higher than required to produce attack in the EPR test. Prior deformation accelerated Cr[sub 2]N precipitation and sensitization kinetics at 700 C, in accordance with previous research on C-based alloys. Sensitization development and deformation effects in high-N austenitic SS as a result of Cr-rich Cr[sub 2]N precipitation were qualitatively analogous to sensitization phenomena ascribed to Cr-rich M[sub 23]C[sub 6] precipitation in C-based alloys. Results indicated high-N, low-C SS was susceptible to intergranular corrosion (IGC) and/or intergranular stress corrosion cracking (IGSCC) as a result of sensitization after thermal exposure to a temperature regime at which Cr[sub 2]N precipitation occurs.

Simmons, J.W.; Atteridge, D.G. (Oregon Graduate Inst. of Science and Technology, Beaverton, OR (United States)); Rawers, J.C. (Bureau of Mines, Albany, OR (United States). Albany Research Center)

1994-07-01

299

High-Sensitive Troponin Measurement in Emergency Department Patients Presenting with Syncope: A Retrospective Analysis  

PubMed Central

Objective To study the relevance of high-sensitive troponin measurements in the acute workup in patients admitted to the emergency department of a large university hospital due to syncope. Methods In this retrospective study all patients admitted to the emergency department because of syncope of the Inselspital, University Hospital Bern between 01 August 2010 and 31 October 2012, with serial determination of high-sensitive troponin (baseline and three hours control) were included. Of all identified patients we obtained data on demographics, laboratory data, ECG as well as on outcome. A change in high-sensitive troponin in the three hours control of +/?30% compared to baseline was considered significant. Results A total of 121 patients with a mean age of 67 years (SD 16) were included in the study. 79 patients (65%) were male and 42 (35%) were female. There was no significant difference in the median high sensitive-troponin level at baseline and in the three hours control (0.01 mcg/L [0.003 to 0.022] versus 0.011 mcg/L [0.003 to 0.022], p?=?0.47). Median percent change in high-sensitive troponin level between baseline and control was 0% (?9.1 to 5). 51 patients (42%) had elevated high-sensitive troponin levels at baseline with 7 patients (6%) showing a dynamic of +/?30% change from the baseline measurement in the 3 hours control. 3 of these patients received coronary angiography due to the dynamic in high-sensitive troponin, none of whom needed intervention for coronary revascularization. Conclusions On basis of the current study, where no single patient took benefit from determination of high-sensitive troponin, measurement of cardiac troponins should be reserved for patients with syncope presenting with symptoms suggestive for the presence of an acute cardiac syndrome.

Funk, Georg-Christian; Leichtle, Alexander B.; Fiedler, Georg Martin; Exadaktylos, Aristomenis K.

2013-01-01

300

Intensity-independent high polarization- or wavelength-sensitive opto-electronic switches  

NASA Astrophysics Data System (ADS)

We present a concept for a highly integrated opto-electronic switch that is sensitive to the wavelength or linear polarization, respectively, of the incident light but operates independent of the optical input power. First demonstration devices show interesting features like high sensitivity, steep switching flanks, a switching contrast of up to 60dB and a photoconductive gain of up to 50dB. Furthermore, the devices can be used for both threshold and bistable switching.

Spieler, J.; Müller, M.; Kippenberg, T.; Kiesel, P.; Krieger, T.; Malzer, S.; Döhler, G. H.

2002-03-01

301

Intensity-independent high polarization- or wavelength-sensitive opto-electronic switches  

Microsoft Academic Search

We present a concept for a highly integrated opto-electronic switch that is sensitive to the wavelength or linear polarization, respectively, of the incident light but operates independent of the optical input power. First demonstration devices show interesting features like high sensitivity, steep switching flanks, a switching contrast of up to 60dB and a photoconductive gain of up to 50dB. Furthermore,

J. Spieler; M. Müller; T. Kippenberg; P. Kiesel; T. Krieger; S. Malzer; G. H Döhler

2002-01-01

302

High-Sensitivity Optical Monitoring of a Micromechanical Resonator with a Quantum-Limited Optomechanical Sensor  

Microsoft Academic Search

We experimentally demonstrate the high-sensitivity optical monitoring of a micromechanical resonator and its cooling by active control. Coating a low-loss mirror upon the resonator, we have built an optomechanical sensor based on a very high-finesse cavity (30 000). We have measured the thermal noise of the resonator with a quantum-limited sensitivity at the 10-19m\\/Hz level, and cooled the resonator down

O. Arcizet; P.-F. Cohadon; T. Briant; M. Pinard; A. Heidmann; J.-M. Mackowski; C. Michel; L. Pinard; O. Français; L. Rousseau

2006-01-01

303

A 10 Gb\\/s high sensitivity, monolithically integrated p-i-n-HEMT optical receiver  

Microsoft Academic Search

A high-sensitivity, monolithically integrated optical receiver, composed of a p-i-n-PD and high electron mobility transistors (p-i-n-HEMTs) is described. The receiver sensitivity is -17.3 dBm at a bit error rate of 1×10-9 for a 10-Gb\\/s non-return-to-zero (NRZ) lightwave signal. This value is the best result yet reported for 10-Gb\\/s monolithically integrated receivers. The sensitivity is -30.6 dBm if an erbium-doped fiber

Y. Akatsu; Y. Miyagawa; Y. Miyamoto; Y. Kobayashi; Y. Akahori

1993-01-01

304

New Generation of High Sensitivity Airborne Potassium Magnetometers for Mineral Exploration Applications  

NASA Astrophysics Data System (ADS)

In the 90's, GEM developed a Potassium magnetometer system that met many of the requirements for "high detail mapping", including high sensitivity, absolute accuracy and minimal orientation errors. Now, this work has been extended with the development of a new Potassium magnetometer / gradiometer for very high sensitivity operation. This paper consists of a short review of two key types of quantum magnetometers (Overhauser and Optically Pumped) - focusing on the development and field testing of a new Potassium system. The new technology provides several advantages over standard optically pumped systems, including high sensitivity, gradient tolerance and bandwidth; "clean" geophysical signal: high speed of operation, high absolute accuracy; ability to combine magnetometer and EM system. Case history data are also provided. Processing methods include corrections, filtering, and gridding. Final conclusions relate these results to the targets shown in original site design records.

Hrvoic, I.

2007-12-01

305

High-resolution and high-intensity neutron diffractometer with linear position-sensitive detector  

NASA Astrophysics Data System (ADS)

The characteristics of a neutron diffractometer using a 3He one-dimensional position-sensitive detector (PSD) with delay line readout, a 200 (length) /× 100 (height) mm2 active window and 2.5mm spatial resolution have been studied and compared with those of the High-Resolution Powder Diffractometer (HRPD) of KAERI with 32 3He conventional tube (?50mm) detectors and Soller collimators /(10') before detectors. For the sample to PSD distance R=1200mm, the PSD subtends /8° angle of /2? and provides the resolution and the peak-to-background ratio close to that for HRPD. Time for scanning (with the same statistics) of a 0-/160° interval is about 1.6 times longer and the multi-PSD system providing efficiency about 10 times higher than HRPD is proposed. Because of the small angle subtended by the PSD, the parasitic peaks from the sample environment are eliminated and operation without an oscillating radial collimator is possible. Additionally, the proposed diffractometer has an advantage for small samples.

Lee, Chang-Hee; Moon, Myung-Kook; Em, V. T.; Choi, Young-Nam; Oh, Hwa-Suk; Nam, Uk-Won

2003-08-01

306

Sensitivity of the High Altitude Water Cherenkov Experiment to observe Gamma-Ray Bursts  

NASA Astrophysics Data System (ADS)

Ground based telescopes have marginally observed very high energy emission (>100GeV) from gamma-ray bursts(GRB). For instance, Milagrito observed GRB970417a with a significance of 3.7 sigmas over the background. Milagro have not yet observed TeV emission from a GRB with its triggered and untriggered searches or GeV emission with a triggered search using its scalers. These results suggest the need of new observatories with higher sensitivity to transient sources. The HAWC (High Altitute Water Cherenkov) observatory is proposed as a combination of the Milagro tecnology with a very high altitude (>4000m over see level) site. The expected HAWC sensitivity for GRBs is at least >10 times the Milagro sensitivity. In this work HAWC sensitivity for GRBs is discussed for different detector configurations such as altitude, distance between PMTs, depth under water of PMTs, number of PMTs required for a trigger, etc.

González, M. M.

307

Ultra-high sensitivity of super carbon-nanotube-based mass and strain sensors  

NASA Astrophysics Data System (ADS)

Based on the molecular structure mechanics method, the dynamic properties of super carbon nanotubes (STs), together with ST-based mass and strain sensors, are investigated. The following results are obtained: (a) the fundamental frequency of the STs is found to be lower than that of the single-wall carbon nanotube (SWCNT); (b) the STs may be a potential ultra-high sensitivity mass sensor with a sensitivity about 10-24 g, which is much higher than that of SWCNT-based mass sensors (10-21 g) (c) the ST-based strain sensor has a sensitivity as high as 887 Hz/nanostrain, which is also higher than that of SWCNT-based strain sensors. The obtained results suggest that the STs could be used to design the new generation of sensors due to its high sensitivity and ultra-low density.

Li, Ying; Qiu, Xin Ming; Yang, Fan; Wang, Xi-Shu; Yin, Yajun

2008-04-01

308

Ultra-high sensitivity of super carbon-nanotube-based mass and strain sensors.  

PubMed

Based on the molecular structure mechanics method, the dynamic properties of super carbon nanotubes (STs), together with ST-based mass and strain sensors, are investigated. The following results are obtained: (a) the fundamental frequency of the STs is found to be lower than that of the single-wall carbon nanotube (SWCNT); (b) the STs may be a potential ultra-high sensitivity mass sensor with a sensitivity about 10(-24) g, which is much higher than that of SWCNT-based mass sensors (10(-21) g); (c) the ST-based strain sensor has a sensitivity as high as 887 Hz/nanostrain, which is also higher than that of SWCNT-based strain sensors. The obtained results suggest that the STs could be used to design the new generation of sensors due to its high sensitivity and ultra-low density. PMID:21825644

Li, Ying; Qiu, Xinming; Yang, Fan; Wang, Xi-Shu; Yin, Yajun

2008-03-18

309

Slow light engineering for high Q high sensitivity photonic crystal microcavity biosensors in silicon  

PubMed Central

Current trends in photonic crystal microcavity biosensors in silicon-on-insulator (SOI), that focus on small and smaller sensors have faced a bottleneck trying to balance two contradictory requirements of resonance quality factor and sensitivity. By simultaneous control of the radiation loss and optical mode volumes, we show that both requirements can be satisfied simultaneously. Microcavity sensors are designed in which resonances show highest Q ~9,300 in the bio-ambient phosphate buffered saline (PBS) as well as highest sensitivity among photonic crystal biosensors. We experimentally demonstrated mass sensitivity 8.8 atto-grams with sensitivity per unit area of 0.8 picograms/mm2 Highest sensitivity, irrespective of the dissociation constant Kd, is demonstrated among all existing label-free optical biosensors in silicon at the concentration of 0.1?g/ml.

Chakravarty, Swapnajit; Zou, Yi; Lai, Wei-Cheng; Chen, Ray T.

2012-01-01

310

Slow light engineering for high Q high sensitivity photonic crystal microcavity biosensors in silicon.  

PubMed

Current trends in photonic crystal microcavity biosensors in silicon-on-insulator (SOI), that focus on small and smaller sensors have faced a bottleneck trying to balance two contradictory requirements of resonance quality factor and sensitivity. By simultaneous control of the radiation loss and optical mode volumes, we show that both requirements can be satisfied simultaneously. Microcavity sensors are designed in which resonances show highest Q ? 9300 in the bio-ambient phosphate buffered saline (PBS) as well as highest sensitivity among photonic crystal biosensors. We experimentally demonstrated mass sensitivity 8.8 atto-grams with sensitivity per unit area of 0.8 pg/mm(2). Highest sensitivity, irrespective of the dissociation constant K(d), is demonstrated among all existing label-free optical biosensors in silicon at the concentration of 0.1 ?g/ml. PMID:22748964

Chakravarty, Swapnajit; Zou, Yi; Lai, Wei-Cheng; Chen, Ray T

2012-06-07

311

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

312

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

2013-03-25

313

Towards high-sensitivity and high-resolution submillimeter-wave video imaging  

NASA Astrophysics Data System (ADS)

Against a background of newly emerged security threats the well-established idea of utilizing submillimeter-wave radiation for personal security screening applications has recently evolved into a promising technology. Possible application scenarios demand sensitive, fast, flexible and high-quality imaging techniques. At present, best results are obtained by passive imaging using cryogenic microbolometers as radiation detectors. Building upon the concept of a passive submillimeter-wave stand-off video camera introduced previously, we present the evolution of this concept in a practical application-ready imaging device. This has been achieved using a variety of measures such as optimizing the detector parameters, improving the scanning mechanism, increasing the sampling speed, and enhancing the camera software. The image generation algorithm has been improved and an automatic sensor calibration technique has been implemented taking advantage of redundancy in the sensor data. The concept is based on a Cassegrain-type mirror optics, an opto-mechanical scanner providing spiraliform scanning traces, and an array of 20 superconducting transition-edge sensors (TES) operated at a temperature of 450-650 mK. The TES are cooled by a closed-cycle cooling system and read out by superconducting quantum interference devices (SQUIDs). The frequency band of operation centers around 350 GHz. The camera can operate at an object distance of 7-10 m. At 9m distance it covers a field of view of 110 cm diameter, achieves a spatial resolution of 2 cm and a pixel NETD (noise equivalent temperature difference) of 0.1-0.4 K. The maximum frame rate is 10 frames per second.

Heinz, Erik; May, Torsten; Born, Detlef; Zieger, Gabriel; Anders, Solveig; Zakosarenko, Viatcheslav; Schubert, Marco; Krause, Torsten; Krüger, André; Schulz, Marco; Meyer, Hans-Georg

2011-05-01

314

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

315

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

316

Design of High Sensitivity, High Resolution Compact Single Photon Imaging Devices for Small Animal and Dedicated Breast Imaging  

SciTech Connect

Imaging the biodistribution of single photon emitting radiotracers in small animals and in the breast with high resolution and high sensitivity is an important challenge. Recent work has shown that single photon emission computed tomography (SPECT) imaging of small objects with coded aperture collimators and iterative image reconstruction may provide an order of magnitude increase in sensitivity yet maintain high spatial resolution. We propose a new system design with compact detectors for single photon small animal and breast imaging. Key features are (1) multipinhole masks for improved sensitivity, (2) pixellated NaI(Tl) scintillator arrays with small crystals for high resolution and (3) flat panel or flangeless compact position sensitive photomultiplier tubes. Analyses for a small animal device with four 10 cm x 20 cm detectors and 1.5 mm detector resolution show that 0.9-1.3 mm resolution in image space could be achieved with high sensitivity for pinholes with 0.5-0.8 mm effective diameters. A design for a breast imager incorporates larger multipinhole masks, 20 cm x 20 cm pixellated detectors and lower magnification. Predicted image resolution in the center of the field of view is 1.9 mm for 0.8 mm pinholes. Additional modeling, iterative image reconstruction tests and device component tests are desirable to optimize device specifications prior to detector construction.

Mark F. Smith; Stan Majewski; Steven R. Meikle; Andrew G. Weisenberger; Vladimir Popov; Randolph F. Wojcik

2001-11-01

317

Design of high sensitive surface plasmon resonance sensor with metallic nano-structure  

NASA Astrophysics Data System (ADS)

In this paper, we have designed and optimized the metallic nano-structures on a conventional surface plasmon resonance (SPR) sensor which induce the localized surface plasmon resonance for an improved sensitivity. Designed SPR sensor was simulated with 3D Finite-difference time-domain method. The sensitivity is maximized to 130.9 degree/RIU when the thickness of film layer TF is 30 nm while that of a conventional SPR sensor is less than 99.6 degree/RIU, and the reflectivity is minimized when TF is 25 nm. The most appropriated diameter of particles is about 35 nm for high sensitivity.

Lee, Byeong-Hyeon; Oh, Geum-Yoon; Kim, Hong-Seung; Lee, Tae-Kyeong; Kim, Doo-Gun; Choi, Young-Wan

2013-03-01

318

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

319

MOSFET sensitivity dependence on integrated dose from high-energy photon beams  

Microsoft Academic Search

The ability of a commercially available dual bias, dual MOSFET dosimetry system to measure therapeutic doses reproducibly throughout its vendor-defined dose-based lifetime has been evaluated by characterizing its sensitivity variation to integrated\\/cumulative doses from high-energy (6 and 15 MV) photon radiotherapy beams. The variation of sensitivity as a function of total integrated dose was studied for three different dose-per-fraction levels;

Bill J. Salter; Martin Fuss; Tomoe Hagio; Shane P. Krafft; James A. Tanyi

2008-01-01

320

Anomalous Strain Rate Sensitivity of Twinning in a Magnesium Alloy at High Temperature  

NASA Astrophysics Data System (ADS)

Anomalous strain rate sensitivity of twinning was observed in a Mg-Al-Mn magnesium alloy during extrusion around 723 K (450 °C). The density of twins decreases as the ram speed increases. At 10 mm min-1, relatively high density twins are activated, but much fewer twins were observed at 30 mm min-1; at 50 mm min-1, twins were hardly seen. The negative strain rate sensitivity was ascribed to the interaction of twinning with defects.

Ma, Quancang; Li, Bin; Mcclelland, Zackery; Horstemeyer, Stephen J.

2013-10-01

321

Optical tweezers position measurement - comparing position sensitive detectors and high-speed cameras  

NASA Astrophysics Data System (ADS)

The design and construction of a low-cost optical trapping system is described. Trapping is performed on 1 micron diameter silica beads using 785 nm light from a diode laser. The particle position is measured using visible 633 nm light imaged onto a position sensitive lateral effect photodiode. We simultaneously acquire images of the trapped particle with a high-speed CCD camera and compare the accuracy of the camera to that obtained with the position sensitive detector. )

Sparks, Laura; Sharpe, John

2010-02-01

322

A high-sensitivity polyimide humidity sensor for monitoring hermetic micropackages  

Microsoft Academic Search

This paper presents the fabrication and characterization of a high-sensitivity polyimide-based humidity sensor for monitoring internal humidity level in anodically-bonded hermetic micropackages. This capacitive sensor is 1 mm on a side, and utilizes CU1512 polyimide film with a thickness in the range of 300-1200 Å sandwiched between 2 metal electrodes to sense moisture. The measured sensitivity for a sensor with

Mehmet Dokmeci; Khalil Najafi

1999-01-01

323

Characteristics of a New High-Sensitivity X-Ray Imaging Tube for Video Topography  

Microsoft Academic Search

A new type of high-sensitivity X-ray imaging tube having an amorphous selenium photoconductive layer with a thickness of 8 mum has been fabricated. Signal charges induced by X-ray photons can be avalanche-multiplied in the photoconductive layer under a large electric field. The sensitivity of the tube reaches the level of individual X-ray photon detection. For the detection of such a

Fumio Sato; Hirotaka Maruyama; Katsuyuki Goto; Isao Fujimoto; Keiichi Shidara; Tatsurou Kawamura; Tadaaki Hirai; Hideyuki Sakai; Jun-ichi Chikawa

1993-01-01

324

Highly efficient photon-to-electron conversion with mercurochrome-sensitized nanoporous oxide semiconductor solar cells  

Microsoft Academic Search

Dye-sensitized solar cells based on nanoporous oxide semiconductor thin films such as TiO2, Nb2O5, ZnO, SnO2, and In2O3 with mercurochrome as the sensitizer were investigated. Photovoltaic performance of the solar cell depended remarkably on the semiconductor materials. Mercurochrome can convert visible light in the range of 400–600nm to electrons. A high incident photon-to-current efficiency (IPCE), 69%, was obtained at 510nm

Kohjiro Hara; Takaro Horiguchi; Tohru Kinoshita; Kazuhiro Sayama; Hideki Sugihara; Hironori Arakawa

2000-01-01

325

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

326

High Sensitivity and Resolution Decimetric Spectroscope: Preliminary Analysis of Solar Bursts.  

National Technical Information Service (NTIS)

High sensitivity radio spectroscope in conjunction with a 9 meter diameter polar mounted antenna has been put into regular operation since December 1990. Spectroscope operates over band of 1600 +/- 100 MHz with high time (20-100 ms) and frequency (0.3-3 M...

F. C. R. Fernandes

1992-01-01

327

BIRD640: SCD's high sensitivity VGA VOx mu-bolometer detector  

Microsoft Academic Search

In this paper we report preliminary data of BIRD640, which is a high-sensitivity (50 mK @ F\\/1, 60Hz) VGA format detector with 25 mum pitch. This high performance is achieved by utilizing an improved pixel design. The product is architecturally compatible to BIRD384 and contains SCD's proprietary unique features (e.g. \\

A. Fraenkel; U. Mizrahi; L. Bikov; A. Giladi; A. Adin; N. Shiloah; E. Malkinson; T. Czyzewski; A. Amsterdam; Y. Sinai

2007-01-01

328

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

329

A highly sensitive microsystem based on nanomechanical biosensors for genomics applications  

Microsoft Academic Search

Microcantilever-based biosensors are a promising tool to detect biomolecular interactions in a direct way with high accuracy. We show the development of a portable biosensor microsystem able to detect nucleic acid hybridization with high sensitivity. The microsystem comprises an array of 20 micromechanical cantilevers produced in silicon technology, a polymer microfluidic system for delivery of the samples, an array of

L. M. Lechuga; J. Tamayo; M. Álvarez; L. G. Carrascosa; A. Yufera; R. Doldán; E. Peralías; A. Rueda; J. A. Plaza; K. Zinoviev; C Domínguez; A. Zaballos; M. Moreno; C. Martínez-A; D. Wenn; N. Harris; C. Bringer; V. Bardinal; T. Camps; C. Vergnenègre; C. Fontaine; V. Díaz; A. Bernad

2006-01-01

330

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

331

Determination of Zilpaterol in Horse Urine from Withdrawal Day 0 to Day 21 by UPLC-MS/MS and ELISA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Zilpaterol is a beta-adrenergic agonist that is approved in the United States, Mexico and South Africa as a feed additive to increase weight gain and improve feed efficiency of cattle. Beta-adrenergic agonists have a long history of illicit and off-label use in livestock, competitive sport animals,...

332

High-resolution versus high-sensitivity SPECT imaging with geometric blurring compensation for various parallel-hole collimation geometries  

Microsoft Academic Search

Recent studies have shown that trading efficiency for improved resolution may be a good choice for small lesion detection, but utilizing collimator with high efficiency may be more favorable for cardiac single photon emission computed tomography (SPECT). This paper investigates the tradeoffs of geometric-blurring compensation for high-resolution (HR) and high-sensitivity (HS) SPECT imaging with various parallel-hole collimators in terms of

Bin Zhang; Gengsheng L. Zeng

2010-01-01

333

High degree gravitational sensitivity from Mars orbiters for the GMM-1 gravity model  

NASA Astrophysics Data System (ADS)

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.

1994-05-01

334

Ultra-high sensitivity photodetector arrays with integrated amplification and passivation nano-layers  

NASA Astrophysics Data System (ADS)

Miniaturized field-deployable spectrometers used for the rapid analysis of chemical and biological substances require high-sensitivity photo detectors. For example, in a Raman spectroscopy system, the receiver must be capable of high-gain, low-noise detection performance due to the intrinsically weak signals produced by the Raman effects of most substances. We are developing a novel, high-gain hetero-junction phototransistor (HPT) detector which employs two nano-structures simultaneously to achieve 100 times higher sensitivity than InGaAs avalanche photodiodes, the most sensitive commercially available photo-detector in the near infrared (NIR) wavelength range, under their normal operation conditions. Integrated into a detector array, this technology has application for Laser-Induced Breakdown Spectroscopy (LIBS), pollution monitoring, pharmaceutical manufacturing by reaction monitoring, chemical & biological transportation safety, and bio-chemical analysis in planetary exploration.

Yao, Jie; Mokina, Irina A.; Liu, Feng; Wang, Sean; Zhou, Jack; Lange, Michael; Yang, Weiguo; Gardner, Patrick; Peltz, Leora; Frampton, Robert; Hunt, Jeffrey H.

2010-02-01

335

A highly sensitive mean-reverting process in finance and the Euler-Maruyama approximations  

NASA Astrophysics Data System (ADS)

Empirical studies show that the most successful continuous-time models of the short-term rate in capturing the dynamics are those that allow the volatility of interest changes to be highly sensitive to the level of the rate. However, from the mathematics, the high sensitivity to the level implies that the coefficients do not satisfy the linear growth condition, so we can not examine its properties by traditional techniques. This paper overcomes the mathematical difficulties due to the nonlinear growth and examines its analytical properties and the convergence of numerical solutions in probability. The convergence result can be used to justify the method within Monte Carlo simulations that compute the expected payoff of financial productsE For illustration, we apply our results compute the value of a bond with interest rate given by the highly sensitive mean-reverting process as well as the value of a single barrier call option with the asset price governed by this process.

Wu, Fuke; Mao, Xuerong; Chen, Kan

2008-12-01

336

A Highly Sensitive CMOS Digital Hall Sensor for Low Magnetic Field Applications  

PubMed Central

Integrated CMOS Hall sensors have been widely used to measure magnetic fields. However, they are difficult to work with in a low magnetic field environment due to their low sensitivity and large offset. This paper describes a highly sensitive digital Hall sensor fabricated in 0.18 ?m high voltage CMOS technology for low field applications. The sensor consists of a switched cross-shaped Hall plate and a novel signal conditioner. It effectively eliminates offset and low frequency 1/f noise by applying a dynamic quadrature offset cancellation technique. The measured results show the optimal Hall plate achieves a high current related sensitivity of about 310 V/AT. The whole sensor has a remarkable ability to measure a minimum ±2 mT magnetic field and output a digital Hall signal in a wide temperature range from ?40 °C to 120 °C.

Xu, Yue; Pan, Hong-Bin; He, Shu-Zhuan; Li, Li

2012-01-01

337

Optical Transitions in Highly Charged Californium Ions with High Sensitivity to Variation of the Fine-Structure Constant  

NASA Astrophysics Data System (ADS)

We study electronic transitions in highly charged Cf ions that are within the frequency range of optical lasers and have very high sensitivity to potential variations in the fine-structure constant, ?. The transitions are in the optical range despite the large ionization energies because they lie on the level crossing of the 5f and 6p valence orbitals in the thallium isoelectronic sequence. Cf16+ is a particularly rich ion, having several narrow lines with properties that minimize certain systematic effects. Cf16+ has very large nuclear charge and large ionization energy, resulting in the largest ? sensitivity seen in atomic systems. The lines include positive and negative shifters.

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

2012-08-01

338

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

2013-03-19

339

Characteristics of a Highly Sensitive Magnetic Sensor Fabricated from Bulk Superconducting BPSCCO  

NASA Astrophysics Data System (ADS)

The proposed application of magnetic sensors can be divided into those related to the direct measurement of very weak magnetic field, e.g., the biomagnetic field such as that of a magnetocardiogram (MCG), and those related to the measurement of other quantities by means of variations in the magnetic field, e.g., the force sensor used in automobiles and industrial robots. With this in mind, it is necessary to develop a highly sensitive magnetic sensor. In constructing such a highly sensitive magnetic sensor, the present authors have been studying the fabrication of bulk Bi-Pb-Sr-Ca-Cu-O (BPSCCO) as the magnetic sensor. This process makes use of the shock compaction method as a new fabrication technology of the bulk high-critical temperature superconductor (HTS). In the present paper, the criterion for fabricating a highly sensitive magnetic sensor is discussed when systematically changing the sensor thickness between 0.1 and 1.1 mm for sensors fabricated under a shock compaction pressure of 1 GPa. The magnetic sensitivity is found to be related to the value of thickness, and reached an approximate sensitivity value sensitivity of 400 %/(10-4 T) for the sensor with the thickness of 0.1 mm, being about 400 times that of a giant magnetoresitance (GMR) sensor. Experimental results revealed the dependencies of the sensitivity on sensor thickness, shock compaction pressure, and different BPSCCO particle size distributions. In addition, the present authors examined the voltage noise power (VNP) spectrum in order to clarify the voltage fluctuations of the magnetic sensors.

Fujita, Hiroyuki; Miwa, Takahiro; Itoh, Mineo; Kezuka, Hiroshi; Matsumoto, Hitoshi; Kishimura, Hiroaki

340

Effect of particle size in the TL response of natural quartz sensitized with high gamma dose  

NASA Astrophysics Data System (ADS)

The aim of this study is to investigate the effect of particle size in the thermoluminescence (TL) response of natural quartz sensitized with high gamma dose. For this, fragments of a single crystal taken from the Solonópole district (Brazil) were crushed and classified into ten size fractions ranging from 38 ?m to 5 mm. Aliquots of each size fraction were sensitized with 25 kGy of gamma dose of 60Co and heat-treated in a muffle furnace at 400oC. The non-sensitized samples were exposed to test doses between 50 Gy and 5 kGy and the sensitized samples were exposed to a unique test dose equal to 50 mGy. For non-sensitized samples, the TL peak near 325 °C increases with the particle size decreasing. However, in the case of sensitized samples, the TL output near 280 °C increases with the increasing of particle size up to mean grain size equal to 308 ?m. Above 308 ?m, an abrupt reduction in the TL intensity was noticed. These effects are discussed in relation to the specific surface area and the different interaction of high gamma doses with fine and coarse particles of quartz.

Carvalho, A. B., Jr.; Guzzo, P. L.; Sullasi, H. L.; Khoury, H. J.

2010-11-01

341

Nanoporous waveguide sensor with optimized nanoarchitectures for highly sensitive label-free biosensing.  

PubMed

Label-free optical biosensors have attracted much attention, and nanoporous metal-oxide membranes with uniform pore structure and diameter are promising candidates for platforms of label-free optical biosensors. However, development of such sensors with high sensitivity still remains challenging. In this paper, we report on the remarkably enhanced sensitivity of a label-free nanoporous optical waveguide (NPWG) sensor composed of a porous anodic alumina (PAA) waveguiding film and an aluminum cladding film. The enhanced sensitivity was achieved by engineering nanostructures and tuning optical properties of the PAA film. Careful tuning of the porosity, pore density, thickness, and refractive index of the PAA film could significantly improve the sensitivity of the NPWG sensor toward adsorption of bovine serum albumin (BSA) onto the PAA surface, and the optimized sensor responded to the adsorption of BSA with an extraordinarily large red shift (>300 nm) of a waveguide mode due to the large adsorption capacity of the PAA film and the inherently high sensitivity of the waveguide mode. The Fresnel calculations suggested that the potential sensitivity of the NPWG sensor was much higher than that of the conventional surface plasmon resonance (SPR) sensors. PMID:22233297

Hotta, Kazuhiro; Yamaguchi, Akira; Teramae, Norio

2012-01-18

342

Highly sensitive assay for phenylethanolamine N-methyltransferase in human brain  

SciTech Connect

A rapid, highly sensitive assay for phenylethanolamine N-methyltransferase in brain using the natural substrate, norepinephrine, is described. The method is based on the selective adsorption and elution of the reaction product, epinephrine, from alumina. A small but important further lowering of blanks and increase in sensitivity is attained by removal of the radiolabeled substrate, (methyl-/sup 3/H)-S-adenosylmethionine by precipitation as the reineckate prior to adsorption of norepinephrine to alumina. The assay has a sensitivity of 30 fmole and the PNMT activity could be measured in as little as 1 mg (wet wt) of human locus coeruleus tissue. The sensitivity is enhanced by homogenizing tissue in small volumes and removing potential inhibitors by dialysis. We report for the first time PNMT activity in specific regions of the human cerebral and cerebellar cortex.

Burke, W.J.; Hanson, D.M.; Chung, H.D.

1986-01-01

343

Environmental toxicology: population modeling of cod larvae shows high sensitivity to loss of zooplankton prey.  

PubMed

Two factors determine whether pollution is likely to affect a population indirectly through loss of prey: firstly, the sensitivity of the prey to the pollutants, and secondly, the sensitivity of the predator population to loss of prey at the given life stage. We here apply a statistical recruitment model for Northeast Arctic cod to evaluate the sensitivity of cod cohorts to loss of zooplankton prey, for example following an oil spill. The calculations show that cod cohorts are highly sensitive to possible zooplankton biomass reductions in the distribution area of the cod larvae, and point to a need for more knowledge about oil-effects on zooplankton. Our study illustrates how knowledge about population dynamics may guide which indirect effects to consider in environmental impact studies. PMID:21194716

Stige, Leif Christian; Ottersen, Geir; Hjermann, Dag Ø; Dalpadado, Padmini; Jensen, Louise K; Stenseth, Nils Chr

2010-12-30

344

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

345

The nature and nurture of high IQ: an extended sensitive period for intellectual development.  

PubMed

IQ predicts many measures of life success, as well as trajectories of brain development. Prolonged cortical thickening observed in individuals with high IQ might reflect an extended period of synaptogenesis and high environmental sensitivity or plasticity. We tested this hypothesis by examining the timing of changes in the magnitude of genetic and environmental influences on IQ as a function of IQ score. We found that individuals with high IQ show high environmental influence on IQ into adolescence (resembling younger children), whereas individuals with low IQ show high heritability of IQ in adolescence (resembling adults), a pattern consistent with an extended sensitive period for intellectual development in more-intelligent individuals. The pattern held across a cross-sectional sample of almost 11,000 twin pairs and a longitudinal sample of twins, biological siblings, and adoptive siblings. PMID:23818653

Brant, Angela M; Munakata, Yuko; Boomsma, Dorret I; Defries, John C; Haworth, Claire M A; Keller, Matthew C; Martin, Nicholas G; McGue, Matthew; Petrill, Stephen A; Plomin, Robert; Wadsworth, Sally J; Wright, Margaret J; Hewitt, John K

2013-07-01

346

Design of High Sensitivity, High Resolution Compact Single Photon Imaging Devices for Small Animal and Dedicated Breast Imaging  

SciTech Connect

Imaging the biodistribution of single photon emitting radiotracers in small animals and in the breast with high resolution and high sensitivity is an important challenge. Recent work has shown that single photon emission computed tomography (SPECT) imaging of small objects with coded aperture collimators and iterative image reconstruction may provide an order of magnitude increase in sensitivity yet maintain high spatial resolution. We propose a new system design with compact detectors for single photon small animal and breast imaging. Key features are (1) mulitpinhole masks for improved sensitivity, (2) pixellated NaI(Tl) scintillator arrays with small crystals for high resolution and (3) flat panel or flangeless compact position sensitive photomultiplier tubes. Analyses for a multipinhole small animal device with four 10 cm x 20 cm detectors and 1.5 mm detector resolution indicate that 0.9-1.3 mm resolution in image space could be achieved for 0.5-0.8 mm diameter pinholes with geometric sensitivity of 0.2-0.6%, where a point in the brain is imaged through 20 pinholes/mask. A design for a multipinhole breast imager incorporates 20 cm x 20 cm pixellated detectors and lower magnification. Predicted image resolution in the center of the field of view is 1.9 mm for 0.8 mm pinholes, with sensitivity of about 0.045% in the center of the field of view for breast tissue imaged through 20 pinholes/mask. Additional modeling, iterative image reconstruction, device component and phantom tests are desirable to optimize device specifications.

Mark F. Smith; Stan Majewski; Steven R. Meikle; Andrew G. Weisenberger; Vladmimir Popov; Randolph F. Wojcik

2001-12-01

347

Polymer Microring Resonators for High-Sensitivity and Wideband Photoacoustic Imaging  

PubMed Central

Polymer microring resonators have been exploited for high-sensitivity and wideband photoacoustic imaging. To demonstrate high-sensitivity ultrasound detection, high-frequency photoacoustic imaging of a 49-?m-diameter black bead at an imaging depth of 5 mm was imaged photoacoustically using a synthetic 2-D array with 249 elements and a low laser fluence of 0.35 mJ/cm2. A bandpass filter with a center frequency of 28 MHz and a bandwidth of 16 MHz was applied to all element data but without signal averaging, and a signal-to-noise ratio of 16.4 dB was obtained. A wideband detector response is essential for imaging reconstruction of multiscale objects, e.g., various sizes of tissues, by using a range of characteristic acoustic wavelengths. A simulation of photoacoustic tomography of beads shows that objects with their boundaries characteristic of high spatial frequencies and the inner structure primarily of low spatial frequency components can be faithfully reconstructed using such a detector. Photoacoustic tomography experiments of 49- and 301-?m-diameter beads were presented. A high resolution of 12.5 ?m was obtained. The boundary of a 301-?m bead was imaged clearly. The results demonstrated that the high sensitivity and broadband response of polymer microring resonators have potential for high resolution and high-fidelity photoacoustic imaging.

Chen, Sung-Liang; Huang, Sheng-Wen; Ling, Tao; Ashkenazi, Shai; Guo, L. Jay

2010-01-01

348

High excitation transfer efficiency from energy relay dyes in dye-sensitized solar cells.  

PubMed

The energy relay dye, 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), was used with a near-infrared sensitizing dye, TT1, to increase the overall power conversion efficiency of a dye-sensitized solar cell (DSC) from 3.5% to 4.5%. The unattached DCM dyes exhibit an average excitation transfer efficiency (ETE) of 96% inside TT1-covered, mesostructured TiO(2) films. Further performance increases were limited by the solubility of DCM in an acetonitrile based electrolyte. This demonstration shows that energy relay dyes can be efficiently implemented in optimized dye-sensitized solar cells, but also highlights the need to design highly soluble energy relay dyes with high molar extinction coefficients. PMID:20617816

Hardin, Brian E; Yum, Jun-Ho; Hoke, Eric T; Jun, Young Chul; Péchy, Peter; Torres, Tomás; Brongersma, Mark L; Nazeeruddin, Md Khaja; Grätzel, Michael; McGehee, Michael D

2010-08-11

349

A highly sensitive fiber optic sensor based on two-core fiber for refractive index measurement.  

PubMed

A simple and compact fiber optic sensor based on a two-core fiber is demonstrated for high-performance measurements of refractive indices (RI) of liquids. In order to demonstrate the suitability of the proposed sensor to perform high-sensitivity sensing in a variety of applications, the sensor has been used to measure the RI of binary liquid mixtures. Such measurements can accurately determine the salinity of salt water solutions, and detect the water content of adulterated alcoholic beverages. The largest sensitivity of the RI sensor that has been experimentally demonstrated is 3,119 nm per Refractive Index Units (RIU) for the RI range from 1.3160 to 1.3943. On the other hand, our results suggest that the sensitivity can be enhanced up to 3485.67 nm/RIU approximately for the same RI range. PMID:24152878

Guzmán-Sepúlveda, José Rafael; Guzmán-Cabrera, Rafael; Torres-Cisneros, Miguel; Sánchez-Mondragón, José Javier; May-Arrioja, Daniel Alberto

2013-10-22

350

Gold nanoparticle enlargement coupled with fluorescence quenching for highly sensitive detection of analytes.  

PubMed

We report a versatile and facile route for highly sensitive detection of analytes through coupling the enlargement of gold nanoparticles with fluorescence quenching. The fluorescence intensity of dye molecules (e.g., fluorescein or rhodamine B) significantly decreased with the increasing concentration of reducing agents, such as hydrogen peroxide and hydroquinone. The sensitivity for the detection of reducing agents was much higher than that of other methods based on the absorbance measurement of enlarged gold nanoparticles or quantum-dot-enzyme hybridization. We could successfully detect acetylthiocholine with the detection limit of several nanomolar concentration using an enzymatic reaction by acetylcholine esterase, a key route for the detection of toxic organophosphate compounds. The fluorescence quenching approach described in this report requires only a simple addition of fluorescence dye to the reaction solution without any chemical modification. The strategy of fluorescence quenching coupled with nanoparticle growth would provide a new horizon for the development of highly sensitive optical biosensors. PMID:19874013

Lim, Seong Yoon; Kim, Jae Hong; Lee, Joon Seok; Park, Chan Beum

2009-12-01

351

Dynamic and clustering model of bacterial chemotaxis receptors: Structural basis for signaling and high sensitivity  

PubMed Central

Bacterial chemotaxis receptors can detect a small concentration gradient of attractants and repellents in the environment over a wide range of background concentration. The clustering of these receptors to form patches observed in vivo and in vitro has been suspected as a reason for the high sensitivity, and such wide dynamic range is thought to be due to the resetting of the receptor sensitivity threshold by methylation/demethylation of the receptors. However, the mechanisms by which such high sensitivity is achieved and how the methylation/demethylation resets the sensitivity are not well understood. A molecular modeling of an intact bacterial chemotaxis receptor based on the crystal structures of a cytoplasmic domain and a periplasmic domain suggests an interesting clustering of three dimeric receptors and a two-dimensional, close-packed lattice formation of the clusters, where each receptor dimer contacts two other receptor dimers at the cytoplasmic domain and two yet different receptor dimers at the periplasmic domain. This interconnection of the receptors to form a patch of receptor clusters suggests a structural basis for the high sensitivity of the bacterial chemotaxis receptors. Furthermore, we present crystallographic data suggesting that, in contrast to most molecular signaling by conformational changes and/or oligomerization of the signaling molecules, the changes in dynamic property of the receptors on ligand binding or methylation may be the language of the signaling by the chemotaxis receptors. Taken together, the changes of the dynamic property of one receptor propagating mechanically to many others in the receptor patch provides a plausible, simple mechanism for the high sensitivity and the dynamic range of the receptors.

Kim, Sung-Hou; Wang, Weiru; Kim, Kyeong Kyu

2002-01-01

352

Tumor necrosis factor-induced release of endogenous fatty acids analyzed by a highly sensitive high =performance liquid chromatography method  

Microsoft Academic Search

A highly sensitive method to determine agonist-in- duced release of endogenous fatty acids from cells in culture was developed using high-performance liquid chromatogra- phy and fluorescence detection. Fatty acids were selectively derivatized with I-pyrenyldiazomethane and separated on a LC,, reversed phase column using an acetonitrile-water gra- dient. The detection limit was approx. 20 fmol and the recov- ery of the

Ole-Lars Brekke; Erling Sagen; Kristian S. Bjerve

353

A highly sensitive biological detection substrate based on TiO2 nanowires supporting gold nanoparticles  

Microsoft Academic Search

Surface enhanced Raman scattering (SERS) has attracted widespread concern in the field of bioassay because it can enhance normally weak Raman signal by several orders of magnitude and facilitate the highly sensitive detection of molecules. Conventional SERS substrates are prepared by placing metal nanoparticles on a planar surface. Here we show a unique SERS substrate stacked by disordered TiO2 nanowires

Yuan Zenga; Hai-jun Tana; Xiu-Lan Chenga; Rui Chenb; Ying Wangb

2011-01-01

354

Longevity Tests of High-Sensitivity BD-PND Bubble Dosimeters  

National Technical Information Service (NTIS)

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 d...

R. Radev E. Carlberg

2002-01-01

355

The AntiMatter Spectrometer for high sensitivity searches of anti-nuclei in space  

Microsoft Academic Search

The apparent absence of antimatter (anti-helium, anti-carbon, etc.) in the universe is a major puzzle of particle physics. The Anti-Matter Spectrometer is a high resolution tracking detector under construction, that will improve the sensitivity for antimatter searches by a factor of more than 104, while orbiting around the Earth on the space station ISSA for >3 years.

W. Wallraff

1996-01-01

356

A highly sensitive mixed lanthanide metal-organic framework self-calibrated luminescent thermometer.  

PubMed

A new mixed lanthanide metal-organic framework thermometer Tb0.9Eu0.1PIA with the significantly high sensitivity of 3.53% per K has been realized by making use of an organic ligand, 5-(pyridin-4-yl)isophthalate, with higher triplet state energy. PMID:24063306

Rao, Xingtang; Song, Tao; Gao, Junkuo; Cui, Yuanjing; Yang, Yu; Wu, Chuande; Chen, Banglin; Qian, Guodong

2013-10-08

357

Constructing a High-Sensitivity, Computer-Interfaced, Differential Thermal Analysis Device for Teaching and Research  

ERIC Educational Resources Information Center

|The construction of a new highly-sensitive, computer-interfaced, differential thermal analysis (DTA) device, used for gathering different information about the chemical reactions, is described. The instrument provides a better understanding about the phase transitions, phase diagrams and many more concepts to the students.|

Martinez, L. M.; Videa, M.; Mederos, F.; Mesquita, J.

2007-01-01

358

A highly sensitive fluorogenic chemodosimeter for rapid visual detection of phosgene.  

PubMed

A highly sensitive chemodosimeter was identified from a panel of rhodamine derivatives for rapid and visual detection of phosgene with a detection limit of 50 nM triphosgene. Visual detection of gaseous phosgene with chemodosimeter absorbed paper strips was demonstrated. PMID:22227622

Wu, Xuanjun; Wu, Zhisheng; Yang, Yuhui; Han, Shoufa

2012-01-06

359

Lifetime Based Temperature and Velocity Measurement using High-Speed Camera and Temperature Sensitive Particles  

Microsoft Academic Search

A simultaneous measurement technique of velocity and temperature distribution in a fluid flow was developed. Particle image velocimetry (PIV) was combined with a lifetime based scalar measurement technique. A measurement method based on the luminescent lifetime is appropriate for detecting the transient temperature field. Developed method needs a high speed camera, a laser (one excitation wave length) and temperature sensitive

Satoshi Someya; Mitsunori Uchida; Kaoru Tominaga; Keiko Ishii; Yanrong Li; Koji Okamoto

2009-01-01

360

Miller oscillators for high sensitivity quartz crystal microbalance sensors in damping media  

Microsoft Academic Search

The paper presents a new contribution to the design of quartz crystal oscillators for high sensitivity microbalance sensors used in liquid media. The oscillation condition for the Miller configuration was studied in order to optimize the values of the components to obtain oscillators for use in extreme conditions of damping. The equations relating the value of the active and passive

L. Rodriguez-Pardo; J. Farina; C. Gabrielli; H. Perrot; R. Brendel

2004-01-01

361

Highly sensitive and frequency-tunable THz detector using carbon nanotube quantum dots  

Microsoft Academic Search

We have developed a new type of THz detector using carbon nanotube quantum dots. We found that THz illumination generates new-side currents, whose peak position linearly depends on the THz-photon energy. This observation leads to highly sensitive and frequency-tunable detection of THz photons.

Yukio Kawano; Tomoko Fuse; Seiko Toyokawa; Takeo Uchida; Koji Ishibashi

2008-01-01

362

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

Microsoft Academic Search

Single nucleotide polymorphism (SNP) genotyping is attracting extensive attentions owing to its direct connections with human diseases including cancers. Here, we have developed a highly sensitive chemiluminescence biosensor based on circular strand-displacement amplification and the separation by magnetic beads reducing the background signal for point mutation detection at room temperature. This method took advantage of both the T4 DNA ligase

Chao Shi; Yujie Ge; Hongxi Gu; Cuiping Ma

2011-01-01

363

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

NASA Astrophysics Data System (ADS)

The paper presents a piezoresistive absolute micro pressure sensor, which is of great benefits for altitude location. In this investigation, the design, fabrication, and test of the sensor are involved. By analyzing the stress distribution of sensitive elements using finite element method, a novel structure through the introduction of sensitive beams into traditional bossed diaphragm is built up. The proposed configuration presents its advantages in terms of high sensitivity and high overload resistance compared with the conventional bossed diaphragm and flat diaphragm structures. Curve fittings of surface stress and deflection based on ANSYS simulation results are performed to establish the equations about the sensor. Nonlinear optimization by MATLAB is carried out to determine the structure dimensions. The output signals in both static and dynamic environments are evaluated. Silicon bulk micromachining technology is utilized to fabricate the sensor prototype, and the fabrication process is discussed. Experimental results demonstrate the sensor features a high sensitivity of 11.098 ?V/V/Pa in the operating range of 500 Pa at room temperature, and a high overload resistance of 200 times overpressure to promise its survival under atmosphere. Due to the excellent performance above, the sensor can be applied in measuring the absolute micro pressure lower than 500 Pa.

Yu, Zhongliang; Zhao, Yulong; Sun, Lu; Tian, Bian; Jiang, Zhuangde

2013-01-01

364

Particular application of a highly sensitive optical projection system in physical experiments  

NASA Astrophysics Data System (ADS)

The possible use of a highly sensitive laser projection system for the amplification and phase conjugation of low-intensity optical radiation has been investigated experimentally. It was shown that the spatial structure of radiation spontaneously scattered in various media can be recorded, and that the interference of low-intensity light beams with a complex transverse structure can be investigated using this approach.

Kulagin, O. V.; Pasmanik, G. A.; Potlov, P. B.; Shilov, A. A.

1991-09-01

365

Multisubstrate-compatible ELISA procedures for rapid and high-sensitivity immunoassays  

Microsoft Academic Search

This protocol describes an improved and optimized approach to develop rapid and high-sensitivity ELISAs by covalently immobilizing antibody on chemically modified polymeric surfaces. The method involves initial surface activation with KOH and an O2 plasma, and then amine functionalization with 3-aminopropyltriethoxysilane. The second step requires covalent antibody immobilization on the aminated surface, followed by ELISA. The ELISA procedure developed is

Chandra Kumar Dixit; Sandeep Kumar Vashist; Brian D MacCraith; Richard O'Kennedy

2011-01-01

366

Development of a Highly Sensitive Optically Pumped Atomic Magnetometer for Biomagnetic Field Measurements: A Phantom Study  

Microsoft Academic Search

We developed a highly sensitive optically pumped atomic magnetometer for measuring biomagnetic fields from the human body noninvasively. The sensor head was a cubic Pyrex glass cell containing potassium metal and buffer gases. A pump laser beam for spin-polarizing potassium atoms and a probe laser beam for detecting magneto-optical rotation crossed at right angles in the cell, which was heated

Shuji Taue; Yasuyuki Sugihara; Tetsuo Kobayashi; Sunao Ichihara; Kiyoshi Ishikawa; Natsuhiko Mizutani

2010-01-01

367

Human MCG measurements with a high-sensitivity potassium atomic magnetometer  

Microsoft Academic Search

Measuring biomagnetic fields, such as magnetocardiograms (MCGs), is important for investigating biological functions. To address to this need, we developed an optically pumped atomic magnetometer. In this study, human MCGs were acquired using a potassium atomic magnetometer without any modulating systems. The sensitivity of the magnetometer is comparable to that of high-Tc superconducting quantum interference devices (SQUIDs) and is sufficient

K Kamada; Y Ito; T Kobayashi

2012-01-01

368

A novel high-throughput on-wafer electromechanical sensitivity characterization system for piezoresistive cantilevers  

Microsoft Academic Search

In this work we present the development of a new set-up that allows on-wafer sensitivity characterization of piezoresistive cantilevers. In this way we reduce considerably the testing time compared to the techniques available up to date but at the same time we maintain a high measurement precision. Moreover it can be easily used for characterization of broad types of batch

G. Tosolini; L. G. Villanueva; F. Perez-Murano; J. Bausells

2012-01-01

369

High sensitive rapid visual detection of sulfadimethoxine by label-free aptasensor.  

PubMed

Quickly and sensitively detection of antibiotic residues in animal products often requires time-consuming techniques and expensive instrumentation. To address these limitations, a high sensitive aptasensor for sulfadimethoxine (SDM) using unmodified gold nanoparticles (AuNPs) was developed in the present study. The assay sensitivity was improved by optimizing several key parameters such as the amount of aptamer adsorbed to AuNPs, the concentration of salt and the AuNPs pH value. To our knowledge, this is the first time to investigate the effect of AuNPs pH value on the sensitivity of aptamer-AuNPs based label-free assay. The best procedure for SDM analysis in our system was: the pH value at 8.0, and the concentration of aptamer at 2 ?M, and the concentration of salt at 2 M. The linear range for the current analytical system was from 50 ng/mL to 1 ?g/mL, and the detection limit was 50 ng/mL, which is lower than the Maximum Residue Limit (MRL) (100 ng/mL) in edible animal tissues regulated by China and European commission. Our study provides a simple, fast, and easy to read method for SDM analysis with high sensitivity, which can be applied in future on-site detection in animal products. PMID:23228493

Chen, Ailiang; Jiang, Xiaoling; Zhang, Weiwei; Chen, Gang; Zhao, Yan; Tunio, Tarique Muhammad; Liu, Jinchuan; Lv, Zhenzhen; Li, Cheng; Yang, Shuming

2012-10-30

370

A high sensitivity satellite-borne television camera for the detection of auroras.  

PubMed

A high sensitivity satellite-borne television camera has been developed to measure such faint light sources as auroras. A secondary electron conduction (SEC) television camera tube is used as the image sensor. In the present application for the Rice/NASA satellites code-named Owls, the tube is exposed by the application of a high voltage pulse of 0.1 sec or 0.2 sec duration. The picture is scanned for about 19 sec, and the video is digitized in synchronism with the satellite PCM system. The television data are then telemetered to the ground either real time or stored in one of the tape recorders. The optical system super-imposes star images on the picture for azimuthal aspect reference. The sensitivity of the slow scan camera was measured; it agrees with the sensitivity of a camera scanning at normal scan rate. Comparison was made of the relative sensitivity of the camera at the wavelength of the three most important auroral components. The camera has sensitivity comparable with the dark-adapted human eye. The weight of the system is 3.9 kg, and the power dissipation is 3.9 W. PMID:20068849

Mende, S B; O'Brien, B J

1968-08-01

371

A High-Resolution Accelerometer With Electrostatic Damping and Improved Supply Sensitivity  

Microsoft Academic Search

In this paper, a charge-balancing accelerometer is presented. A hybrid interface topology is utilised to achieve high resolution, high linearity and low power supply sensitivity. The accelerometer consists of a micromechanical sensor element, a self-balancing bridge (SBB) open-loop readout, AC force feedback and $\\\\Delta \\\\Sigma$ ADC. The SBB converts acceleration to ratiometric voltage. The ratiometric output of the SBB is

Mikail Yucetas; Mika Pulkkinen; Antti Kalanti; Jarno Salomaa; Lasse Aaltonen; Kari Halonen

2012-01-01

372

Sensitivity of high-resolution tropical cyclone intensity forecasts to surface flux parameterization  

Microsoft Academic Search

Surface flux parameterization schemes used in current dynamic models are primarily based upon measurements at low and moderate\\u000a wind speeds. Recent studies show that these parameterization schemes may be incorrect at high wind speeds (e.g., tropical\\u000a cyclone forecasts). Five high-resolution numerical model experiments are designed to assess the sensitivity of tropical cyclone\\u000a intensity forecasts to changes in the surface flux

Chi-Sann Liou

2007-01-01

373

High sensitivity photonic crystal biosensor incorporating nanorod structures for enhanced surface area  

Microsoft Academic Search

The surface area of a photonic crystal biosensor is greatly enhanced through the incorporation of a porous TiO2 film possessing the structure of nanorods into the device. The film is deposited by the glancing angle deposition technique in an e-beam evaporation system. The sensitivity of high surface area sensors is compared with sensors without the high surface area coating. Results

Wei Zhang; Nikhil Ganesh; Ian D. Block; Brian T. Cunningham

2008-01-01

374

Depth of interaction resolution measurements for a high resolution PET detector using position sensitive avalanche photodiodes  

Microsoft Academic Search

We explore dual-ended read out of LSO arrays with two position sensitive avalanche photodiodes (PSAPDs) as a high resolution, high efficiency depth-encoding detector for PET applications. Flood histograms, energy resolution and depth of interaction (DOI) resolution were measured for unpolished LSO arrays with individual crystal sizes of 1.0, 1.3 and 1.5 mm, and for a polished LSO array with 1.3

Yongfeng Yang; Purushottam A. Dokhale; Robert W. Silverman; Kanai S. Shah; Mickel A. McClish; Richard Farrell; Gerald Entine; Simon R. Cherry

2006-01-01

375

Scintillation and detection characteristics of high-sensitivity CeBr3 gamma-ray spectrometers  

NASA Astrophysics Data System (ADS)

Crystal growth and detector fabrication technologies have reached such a state of maturity that high-quality large-volume CeBr3 scintillators can now be produced with dimensions of 2?×2? and well above. We present a study of CeBr3 samples of various dimensions and show that they have a number of advantages over equivalently sized LaBr3:5%Ce for gamma-ray spectroscopy applications requiring high detection sensitivity.

Quarati, F. G. A.; Dorenbos, P.; van der Biezen, J.; Owens, Alan; Selle, M.; Parthier, L.; Schotanus, P.

2013-11-01

376

Sensitive and high-fidelity electrochemical immunoassay using carbon nanotubes coated with enzymes and magnetic nanoparticles  

Microsoft Academic Search

We demonstrate a highly sensitive electrochemical immunosensor based on the combined use of substrate recycling and carbon nanotubes (CNTs) coated with tyrosinase (TYR) and magnetic nanoparticles (MNP). Both TYR and MNP were immobilized on the surface of CNTs by covalent attachment, followed by additional cross-linking via glutaraldehyde treatment to construct multi-layered cross-linked TYR-MNP aggregates (M-EC-CNT). Magnetically capturable, highly active and

Yunxian Piao; Zongwen Jin; Dohoon Lee; Hye-Jin Lee; Hyon-Bin Na; Taeghwan Hyeon; Min-Kyu Oh; Jungbae Kim; Hak-Sung Kim

2011-01-01

377

Sensitization of High-Nitrogen Austenitic Stainless Steels by Dichromium Nitride Precipitation  

Microsoft Academic Search

High-nitrogen (N) stainless steels (SS) are receiving increased attention because of their strength advantages over carbon (C)-alloyed materials, but they have been found susceptible to dichromium nitride (Cr[sub 2]N) precipitation during thermal exposure between [approximately]600 C and 1,050 C. Sensitization susceptibility of a high-N, low-C austenitic SS by Cr[sub 2]N precipitation at 700 C and 900 C was determined using

J. W. Simmons; J. C. Rawers; D. G. Atteridge

1994-01-01

378

DeepSAGE--digital transcriptomics with high sensitivity, simple experimental protocol and multiplexing of samples  

Microsoft Academic Search

Digital transcriptomics with pyrophosphatase based ultra-high throughput DNA sequencing of di-tags provides high sensitivity and cost-effective gene expression profiling. Sample preparation and handling are greatly simplified compared to Serial Analysis of Gene Expression (SAGE). We compare DeepSAGE and LongSAGE data and demonstrate greater power of detection and multiplexing of samples derived from potato. The transcript anal- ysis revealed a great

K. L. Nielsen; A. L. Hogh; Jeppe Emmersen

2006-01-01

379

A fast position sensitive microstrip-gas-chamber detector at high count rate operation  

NASA Astrophysics Data System (ADS)

Testing of a newly developed position sensitive high count rate microstrip gas chamber (MSGC) detector at high count rate operation has been carried out at the Dutch-Belgian x-ray scattering beamline at the European Synchrotron Radiation Facility (Grenoble, France) with a high intensity x-ray beam. The measurements show local count rate capabilities up to approx4.5 x105 counts/s/channel. Experimental data taken with this detector are also shown. These tests show that both time resolution down to 1.5 ms/frame and a reliable operation at high counting rates can be achieved.

Dolbnya, I. P.; Alberda, H.; Hartjes, F. G.; Udo, F.; Bakker, R. E.; Konijnenburg, M.; Homan, E.; Cerjak, I.; Goedtkindt, P.; Bras, W.

2002-11-01

380

High-resolution and high-sensitivity SPECT imaging of breast phantoms  

SciTech Connect

A small field of view gamma camera based on a Position Sensitive Photomultiplier Tube has been used for tomoscintigraphic imaging of breast phantoms. The breast phantoms consist of small hot quantities of 99mTc placed in a plastic pot filled with a lower concentration 99mTc solution. The volume of the hot quantities varied from 0.5 to 0.25 ml and the target to background activity ratio varied from 3:1 to 5:1. The impact of the acquisition time per projection and the number of projections on image quality has been investigated.

George Loudos; N.D. Giokaris; K. Mainta; N. Sakelios; E. Stiliaris; A. Karabarbounis; Costas Papanicolas; V. Spanoudaki; K.S. Nikita; N.K. Uzunoglu; S.C. Archimandritis; A.D. Varvarigou; K.N. Stefanis; Stanislaw Majewski; Andrew Weisenberger; Roberto Pani; D. Maintas

2004-07-01

381

A small mission featuring an imaging x-ray polarimeter with high sensitivity  

NASA Astrophysics Data System (ADS)

We show that meaningful, highly sensitive x-ray polarimetry with imaging capability is possible with a small mission tailored to the NASA Explorer program. Such a mission—derived from the Imaging X-ray Polarimetry Explorer (IXPE) proposed to a previous NASA call—takes advantage of progress in light-weight x-ray optics and in gas pixel detectors to achieve sensitive time-resolved, spectrometric, imaging polarimetry. We outline the main characteristics and requirements of this mission and provide a realistic assessment of its scientific utility for modeling point-like and extended x-ray sources and for studying physical processes (including questions of fundamental physics).

Weisskopf, Martin C.; Baldini, Luca; Bellazini, Ronaldo; Brez, Alessandro; Costa, Enrico; Dissly, Richard; Elsner, Ronald F.; Fabiani, Sergio; Matt, Giorgio; Minuti, Massimo; Muleri, Fabio; O'Dell, Steve; Pinchera, Michele; Ramsey, Brian; Rubini, Alda; Sgro', Carmelo; Soffitta, Paolo; Spandre, Gloria

2013-09-01

382

A terahertz plastic wire based evanescent field sensor for high sensitivity liquid detection.  

PubMed

A highly sensitive detection method based on the evanescent wave of a terahertz subwavelength plastic wire was demonstrated for liquid sensing. Terahertz power spreading outside the wire core makes the waveguide dispersion sensitive to the cladding index variation, resulting in a considerable deviation of waveguide dispersion. Two liquids with transparent appearances, water and alcohol, are easily distinguished based on the waveguide dispersion, which is consistent with theoretical predictions. A melamine alcohol solution with various concentrations is identified successfully, and the detection limit is up to 20ppm, i.e. equivalent to the index variation on the order of 0.01. PMID:19997297

You, Borwen; Liu, Tze-An; Peng, Jin-Long; Pan, Ci-Ling; Lu, Ja-Yu

2009-11-01

383

High-sensitivity visible-blind UV detectors made with organic semiconductors  

NASA Astrophysics Data System (ADS)

High sensitivity visible-blind UV detectors were fabricated with organic semiconductors. The photo-sensitivity at 350 nm reaches 75 mA/Watt, corresponding to quantum efficiency of approximately 27% el/ph. The visible/UV suppression ratio is more than 10(superscript 4) without optical filters. These UV detectors are of linear intensity dependence with fast response time. The simple fabrication process allows these UV detectors to be made in large size, in flexible forms or onto non-planar substrates with low cost. The fabrication process also allows these UV detectors to be integrated with electronic devices or optical devices.

Yu, Gang; Cao, Yong; Srdanov, Gordana

1999-04-01

384

A High-Sensitivity Quadrant Detector for Image-Stabilization Applications  

NASA Astrophysics Data System (ADS)

A description is given of the design and performance of a quadrant detector offering improvements in sensitivity and ease of construction over earlier devices. The optics are compact, and low-noise high-sensitivity operation is achieved with the use of avalanche photodiode detectors. The device is installed on the SIS spectrograph on the CFH 3.6-m telescope and allows image stabilization to be achieved by a tip-tilt mirror system using guide stars as faint as magnitude 18.5.

Stilburn, J.; Fletcher, M.; Leckie, B.; Barrick, G.; Monnet, G.

1997-10-01

385

High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors  

NASA Astrophysics Data System (ADS)

We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m/?m > 2500. The system design is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0-5000 amu in the current configuration). As a demonstration of the system performance we present data from ammonia oxidation on a Pt thin film showing resolved spectra of OH and NH3.

Andersen, T.; Jensen, R.; Christensen, M. K.; Pedersen, T.; Hansen, O.; Chorkendorff, I.

2012-07-01

386

Highly sensitive capacitive immunosensor based on porous silicon-polyaniline structure: Bias dependence on specificity.  

PubMed

Porous silicon/polyaniline (PS/PANI) heterostructure has been prepared electrochemically which provides label free, real-time electrical detection with high sensitivity for the specific model biomolecules (mouse IgG/goat antimouse IgG). The sensor structures based on PS/PANI were prepared easily by directly immobilizing the biomolecule through gluteraldehyde coupler. These structures were used to detect specific biomolecule down to at least a picomolar concentration range and were found to be reusable. High sensitivity and easy processability of PS/PANI structures could be understood by the change in surface charge of the silicon channels in the PS structure that occurs by PANI deposition whilst providing covalent binding with biomolecules with its naturally occurring NH groups. The space charge layer in the PS/PANI channels get further modified by the surface charge change created by the specific analyte-antibody binding giving rise to high sensitivity. It was found that a substrate bias in the accumulation region of porous silicon gives the optimum sensitivity and specificity. PMID:19674886

Betty, C A

2009-07-18

387

A novel high-sensitive miniaturized optical system for fluorescence detection  

NASA Astrophysics Data System (ADS)

This paper presents a novel, high sensitive and miniaturized fluorescence detection system which integrated a LED light source, all necessary optical components and a photodiode with preamplifier into one package about 2 cm x 2 cm x 2 cm especially for the applications of lab-on-a-chip, portable bio-detection system and point-of-care diagnostic system. The prototype has been tested using the fluorescence dye 5-Carboxyfluorescein (5-FAM) dissolved into solvent DMSO (Dimethyl Sulfoxide) and diluted with DI water as the testing solution samples. Resolution approximation method is accepted to evaluate the sensitivity. The testing results prove a remarkable sensitivity at pico-scale molar, around 1.08 pM/L, which should meet the most of bio-detection requirements. This cost-effective detection system can be widely integrated to the portable device and system for fluorescent detection in biological, chemical, medical, point-of-care applications.

Yao, Mingjin; Fang, Ji

2011-02-01

388

High sensitivity photoconductivity based measurement setup for the determination of effective recombination lifetime in silicon wafers  

NASA Astrophysics Data System (ADS)

We describe a high sensitivity measurement setup for the determination of recombination parameters in semiconductors at low levels of carrier injection. The setup is based on a lock-in amplifier and on a commercially available contactless conductivity detector. The information on recombination is extracted through the analysis, assuming quasi-steady-state conditions, of the low frequency, sinusoidally modulated photoconductivity signal induced by the illumination of a 950 nm light emitting diode array. Experimental results show a substantial increase in sensitivity with respect to traditional transient or quasi-steady-state techniques based on the same detection principle. The sensitivity bonus can be exploited for the extension of the carrier injection range for which effective recombination lifetime is measurable, both in the case of p-type and n-type wafers.

Cornagliotti, E.; Kang, X.; Beaucarne, G.; John, J.; Poortmans, J.; Mertens, R.

2009-05-01

389

High-sensitivity atomic magnetometer unaffected by spin-exchange relaxation.  

PubMed

Alkali-metal magnetometers compete with SQUID detectors as the most sensitive magnetic field sensors. Their sensitivity is limited by relaxation due to spin-exchange collisions. We demonstrate a K magnetometer in which spin-exchange relaxation is completely eliminated by operating at high K density and low magnetic field. Direct measurements of the signal-to-noise ratio give a magnetometer sensitivity of 10 fT Hz(-1/2), limited by magnetic noise produced by Johnson currents in the magnetic shields. We extend a previous theoretical analysis of spin exchange in low magnetic fields to arbitrary spin polarizations and estimate the shot-noise limit of the magnetometer to be 2x10(-18) T Hz(-1/2). PMID:12225013

Allred, J C; Lyman, R N; Kornack, T W; Romalis, M V

2002-09-09

390

Highly sensitive and selective gas sensor using hydrophilic and hydrophobic graphenes.  

PubMed

New hydrophilic 2D graphene oxide (GO) nanosheets with various oxygen functional groups were employed to maintain high sensitivity in highly unfavorable environments (extremely high humidity, strong acidic or basic). Novel one-headed polymer optical fiber sensor arrays using hydrophilic GO and hydrophobic reduced graphene oxide (rGO) were carefully designed, leading to the selective sensing of volatile organic gases for the first time. The two physically different surfaces of GO and rGO could provide the sensing ability to distinguish between tetrahydrofuran (THF) and dichloromethane (MC), respectively, which is the most challenging issue in the area of gas sensors. The eco-friendly physical properties of GO allowed for faster sensing and higher sensitivity when compared to previous results for rGO even under extreme environments of over 90% humidity, making it the best choice for an environmentally friendly gas sensor. PMID:23736838

Some, Surajit; Xu, Yang; Kim, Youngmin; Yoon, Yeoheung; Qin, Hongyi; Kulkarni, Atul; Kim, Taesung; Lee, Hyoyoung

2013-01-01

391

High-sensitivity dynamical profilometry with a fiber-based composite interferometer.  

PubMed

We proposed and demonstrated a fiber-based composite interferometer, which can perform surface profile measurements with sensitivity at the nanometer scale. With the proposed phase-compensation mechanism, the phase deviation due to the instability of the optical delay component and environmental perturbations can be simultaneously compensated. The measurement sensitivity and imaging speed can be significantly improved such that the system can be used as a high-speed, high-resolution, and wide-field dynamical imaging system. The axial precision of the system was examined to be 0.82 nm. High-resolution time-lapsed dynamical imaging of onion cells during dehydration processes were performed with this system with one frame captured in 75 s. PMID:23939072

Chang, Chun-Wei; Hou, Max T; Hsu, I-Jen

2013-07-15

392

Mu2e: A High-Sensitivity Charged Lepton Flavor-Violating Search at Fermilab  

NASA Astrophysics Data System (ADS)

The Mu2e Experiment at Fermilab will search for coherent, neutrino-less conversion of a muon into an electron in the field of a nucleus, -circ;+A->A+e^-, with a sensitivity improvement of a factor of 10,000 over existing limits. Such a charged lepton flavor-violating reaction probes new physics complementary to the LHC and can reach a scale unavailable by direct searches at either present or planned high energy colliders. The physics motivation for Mu2e will be presented, as well as the design of the muon beamline and spectrometer. The beamline employs a new design consisting of superconducting solenoids that will produce muons at high efficiency. A scheme by which the experiment can be mounted in the present Fermilab accelerator complex will be described. Prospects for increased sensitivity at future very high intensity sources, such as the Project X linac that is being proposed by Fermilab, will be discussed.

Miller, James

2012-03-01

393

A sensitive, high resolution magic angle turning experiment for measuring chemical shift tensor principal values  

NASA Astrophysics Data System (ADS)

A sensitive, high-resolution 'FIREMAT' two-dimensional (2D) magic-angle-turning experiment is described that measures chemical shift tensor principal values in powdered solids. The spectra display spinning-sideband patterns separated by their isotropic shifts. The new method's sensitivity and high resolution in the isotropic-shift dimension result from combining the 5pi magic-angle-turning pulse sequence, an extension of the pseudo-2D sideband-suppression data rearrangement, and the TIGER protocol for processing 2D data. TPPM decoupling is used to enhance resolution. The method requires precise synchronization of the pulses and sampling to the rotor position. It is shown that the technique obtains 35 natural-abundance 13C tensors from erythromycin in 19 hours, and high quality naturalabundance 15N tensors from eight sites in potassium penicillin V in three days on a 400MHz spectrometer.

Alderman, D. W.

1998-12-01

394

Highly Sensitive and Selective Gas Sensor Using Hydrophilic and Hydrophobic Graphenes  

NASA Astrophysics Data System (ADS)

New hydrophilic 2D graphene oxide (GO) nanosheets with various oxygen functional groups were employed to maintain high sensitivity in highly unfavorable environments (extremely high humidity, strong acidic or basic). Novel one-headed polymer optical fiber sensor arrays using hydrophilic GO and hydrophobic reduced graphene oxide (rGO) were carefully designed, leading to the selective sensing of volatile organic gases for the first time. The two physically different surfaces of GO and rGO could provide the sensing ability to distinguish between tetrahydrofuran (THF) and dichloromethane (MC), respectively, which is the most challenging issue in the area of gas sensors. The eco-friendly physical properties of GO allowed for faster sensing and higher sensitivity when compared to previous results for rGO even under extreme environments of over 90% humidity, making it the best choice for an environmentally friendly gas sensor.

Some, Surajit; Xu, Yang; Kim, Youngmin; Yoon, Yeoheung; Qin, Hongyi; Kulkarni, Atul; Kim, Taesung; Lee, Hyoyoung

2013-06-01

395

Gold nanoparticle thin films fabricated by electrophoretic deposition method for highly sensitive SERS application  

PubMed Central

We report an electrophoretic deposition method for the fabrication of gold nanoparticle (GNP) thin films as sensitive surface-enhanced Raman scattering (SERS) substrates. In this method, GNP sol, synthesized by a seed-mediated growth approach, and indium tin oxide (ITO) glass substrates were utilized as an electrophoretic solution and electrodes, respectively. From the scanning electron microscopy analysis, we found that the density of GNPs deposited on ITO glass substrates increases with prolonged electrophoresis time. The films possess high mechanical adhesion strength and exhibit strong localized surface plasmon resonance (LSPR) effect by showing high SERS sensitivity to detect 1?×?10?7 M rhodamine 6 G in methanol solution. Finally, the relationship between Raman signal amplification capability and GNP deposition density has been further investigated. The results of our experiment indicate that the high-density GNP film shows relatively higher signal amplification capability due to the strong LSPR effect in narrow gap regions between the neighboring particles on the film.

2012-01-01

396

Advanced nanoscale separations and mass spectrometry for sensitive high-throughput proteomics  

SciTech Connect

We review recent development in separations and mass spectrometric instrumentation for sensitive and high-throughput proteomic analyses. These efforts have been primarily focused on the development of high-efficiency (separation peak capacity of ~103) nanoscale liquid chromatography (nanoLC; e.g., flow rates extending down to ~20 nL/min at optimal separation linear velocities through narrow packed capillaries) in combination with advanced mass spectrometry (MS), including high sensitivity and high resolution Fourier transform ion cyclotron resonance (FTICR) MS. This technology enables MS analysis of low nanogram-level proteomic samples (i.e., nanoscale proteomics) with individual protein identification sensitivity at the low zeptomole-level. The resultant protein measurement dynamic range can reach 106 for nanogram-sized proteomic samples, while more abundant proteins can be detected from complex sub-picogram size proteome samples. The average proteome identification throughput using MS/MS is >200 proteins/h for a ~3 h analysis. These qualities provide the foundation for proteomics studies of single or small populations of cells. The instrumental robustness required for automation and providing high quality routine performance nanoscale proteomic analyses is also discussed.

Shen, Yufeng; Smith, Richard D.

2005-06-01

397

Advanced nanoscale separations and mass spectrometry for sensitive high-throughput proteomics.  

PubMed

Recent developments in combined separations with mass spectrometry for sensitive and high-throughput proteomic analyses are reviewed herein. These developments primarily involve high-efficiency (separation peak capacities of approximately 10(3)) nanoscale liquid chromatography (flow rates extending down to approximately 20 nl/min at optimal liquid mobile-phase separation linear velocities through narrow packed capillaries) in combination with advanced mass spectrometry and in particular, high-sensitivity and high-resolution Fourier transform ion cyclotron resonance mass spectrometry. Such approaches enable analysis of low nanogram level proteomic samples (i.e., nanoscale proteomics) with individual protein identification sensitivity at the low zeptomole level. The resultant protein measurement dynamic range can approach 10(6) for nanogram-sized proteomic samples, while more abundant proteins can be detected from subpicogram-sized (total) proteome samples. These qualities provide the foundation for proteomics studies of single or small populations of cells. The instrumental robustness required for automation and providing high-quality routine performance nanoscale proteomic analyses is also discussed. PMID:16000088

Shen, Yufeng; Smith, Richard D

2005-06-01

398

A new highly sensitive broadband ferromagnetic resonance measurement system with lock-in detection  

NASA Astrophysics Data System (ADS)

RF/microwave magnetic measurement systems can be categorized into broadband or narrowband systems. Narrowband systems utilize high Q cavities for magnetic material characterizations such as electron paramagnetic resonance or electron spin resonance. Example broadband characterization systems are permeameters or pulsed inductive magnetometers. Narrowband measurement systems have high sensitivity but limited bandwidth whereas broadband systems suffer from lower sensitivity. In particular, it has been challenging to precisely measure weak magnetization, high anisotropy and high ferromagnetic resonance linewidth across a broad bandwidth. In this work, we report a new highly sensitive broadband resonance measurement system with lock-in detection utilizing a broadband transmission line. The frequency of the RF source is swept while the magnetic field is fixed. The resulting curve of dP/dH versus f is similar to the dP/dH versus H curve from conventional narrowband magnetic measurement system. The imaginary component of magnetic susceptibility ?" is calculated by the equation of ?"(f)=C?(dP/dH*dH/df)df, in which C is a constant and dH/df is determined from the Kittel equation for magnetic films. Broadband measurements of sputtered low-moment lossy NiCr (4?Ms=1100 G) as well as NiFe (4?Ms=11000 G) were taken and compared with conventional broadband measurement using a network analyzer.

Beguhn, S.; Zhou, Ziyao; Rand, S.; Yang, X.; Lou, J.; Sun, N. X.

2012-04-01

399

Design issues in SOI-based high-sensitivity piezoresistive cantilever devices  

NASA Astrophysics Data System (ADS)

In this work, the mechanical design and optimization of high-sensitivity piezoresistive cantilevers used for detecting changes in surface stresses due to binding and hybridization of biomolecules on the surface of the cantilever is investigated. The silicon-based cantilevers are typically of a micron order thickness doped with boron to introduce piezoresistivity. Microcantilever beams can be built as micro-mechanical arrays which could provide a basis for developing devices capable of performing multi-plexed, low-cost genomic and proteomic analyses. This paper provides several design solutions in optimizing the cantilever mechanical design to address the sensitivity required when approaching recognition of single base pairing of DNA molecules. The sensitivity of such piezoresistive cantilevers to the chemo-mechanical stress induced currents depends not only on the cantilever geometric properties, such as depth and width but also on the depth of the piezo layer (dopant) and its doping characteristics. It is often an expensive exercise to determine the optimum design parameters for increased sensitivity, particularly the dopant characteristics for such MEMS devices. A managed solution or parametric solution algorithm based on a finite element simulation is used to help determine optimum location and depth of this piezoresistive layer in the cantilever that maximizes the piezoresistor signals. Further, novel approaches for increasing the sensitivity of piezoresistive cantilevers through selected structural discontinuities are discussed.

Kassegne, Samuel; Madou, Marc J.; Whitten, Ralph; Zoval, Jim V.; Mather, Elizabeth; Sarkar, Kamal; Hodko, Dalibor; Maity, Sandipan

2002-07-01

400

Plasma 24,25-dihydroxyvitamin D concentration of Dahl salt-sensitive rats decreases during high salt intake  

Microsoft Academic Search

Dahl salt-sensitive rats, but not salt-resistant rats, develop hypertension in response to high salt intake. We have previously shown an inverse relationship between plasma 25-hydroxyvitamin D (25-OHD) concentration and blood pressure of Dahl salt-sensitive rats during high salt intake. In this study, we report on the relationship between high salt intake and plasma 24,25-dihydroxyvitamin D (24,25-(OH)2D) concentration of Dahl salt-sensitive

Myrtle Thierry-Palmer; Teclemicael K. Tewolde; Camille Forté; Min Wang; Mohamed A. Bayorh; Nerimiah L. Emmett; Jolanda White; Keri Griffin

2002-01-01

401

High-efficiency dye-sensitized solar cell with three-dimensional photoanode.  

PubMed

Herein, we present a straightforward bottom-up synthesis of a high electron mobility and highly light scattering macroporous photoanode for dye-sensitized solar cells. The dense three-dimensional Al/ZnO, SnO(2), or TiO(2) host integrates a conformal passivation thin film to reduce recombination and a large surface-area mesoporous anatase guest for high dye loading. This novel photoanode is designed to improve the charge extraction resulting in higher fill factor and photovoltage for DSCs. An increase in photovoltage of up to 110 mV over state-of-the-art DSC is demonstrated. PMID:21961905

Tétreault, Nicolas; Arsenault, Eric; Heiniger, Leo-Philipp; Soheilnia, Navid; Brillet, Jérémie; Moehl, Thomas; Zakeeruddin, Shaik; Ozin, Geoffrey A; Grätzel, Michael

2011-10-11

402

A highly sensitive pressure sensor using a Au-patterned polydimethylsiloxane membrane for biosensing applications  

NASA Astrophysics Data System (ADS)

We report on the fabrication and characterization of a highly sensitive pressure sensor using a Au film patterned on a polydimethylsiloxane (PDMS) membrane. The strain-induced change in the film resistance was utilized to perform the quantitative measurement of absolute pressure. The highest sensitivity obtained for a 200 µm thick PDMS film sensor was 0.23/KPa with a range of 50 mm Hg, which is the best result reported so far, over that range, for any pressure sensor on a flexible membrane. The noise-limited pressure resolution was found to be 0.9 Pa (0.007 mm Hg), and a response time of ˜200 ms, are the best reported results for these sensors. The ultrahigh sensitivity is attributed to the strain-induced formation of microcracks, the effect of which on the resistance change was found to be highly reversible within a certain pressure range. A physical model correlating the sensitivity with the sensor parameters and crack geometry has been proposed.

Liu, Xinchuan; Zhu, Yihao; Nomani, Md W.; Wen, Xuejun; Hsia, Tain-Yen; Koley, Goutam

2013-02-01

403

High-affinity potassium transport in barley roots. Ammonium-sensitive and -insensitive pathways.  

PubMed

In an attempt to understand the process mediating K(+) transport into roots, we examined the contribution of the NH(4)(+)-sensitive and NH(4)(+)-insensitive components of Rb(+) transport to the uptake of Rb(+) in barley (Hordeum vulgare L.) plants grown in different ionic environments. We found that at low external Rb(+) concentrations, an NH(4)(+)-sensitive component dominates Rb(+) uptake in plants grown in the absence of NH(4)(+), while Rb(+) uptake preferentially occurs through an NH(4)(+)-insensitive pathway in plants grown at high external NH(4)(+) concentrations. A comparison of the Rb(+)-uptake properties observed in roots with those found in heterologous studies with yeast cells indicated that the recently cloned HvHAK1 K(+) transporter may provide a major route for the NH(4)(+)-sensitive component. HvHAK1 failed to complement the growth of a yeast strain defective in NH(4)(+) transport, suggesting that it could not act as an NH(4)(+) transporter. Heterologous studies also showed that the HKT1 K(+)/Na(+)-cotransporter may act as a pathway for high-affinity Rb(+) transport sensitive to NH(4)(+). However, we found no evidence of an enhancement of Rb(+) uptake into roots due to Na(+) addition. The possible identity of the systems contributing to the NH(4)(+)-insensitive component in barley plants is discussed. PMID:10806246

Santa-María, G E; Danna, C H; Czibener, C

2000-05-01

404

High Sensitivity Gas Detection Using a Macroscopic Three-Dimensional Graphene Foam Network  

PubMed Central

Nanostructures are known to be exquisitely sensitive to the chemical environment and offer ultra-high sensitivity for gas-sensing. However, the fabrication and operation of devices that use individual nanostructures for sensing is complex, expensive and suffers from poor reliability due to contamination and large variability from sample-to-sample. By contrast, conventional solid-state and conducting-polymer sensors offer excellent reliability but suffer from reduced sensitivity at room-temperature. Here we report a macro graphene foam-like three-dimensional network which combines the best of both worlds. The walls of the foam are comprised of few-layer graphene sheets resulting in high sensitivity; we demonstrate parts-per-million level detection of NH3 and NO2 in air at room-temperature. Further, the foam is a mechanically robust and flexible macro-scale network that is easy to contact (without Lithography) and can rival the durability and affordability of traditional sensors. Moreover, Joule-heating expels chemisorbed molecules from the foam's surface leading to fully-reversible and low-power operation.

Yavari, Fazel; Chen, Zongping; Thomas, Abhay V.; Ren, Wencai; Cheng, Hui-Ming; Koratkar, Nikhil

2011-01-01

405

High sensitivity gas detection using a macroscopic three-dimensional graphene foam network.  

PubMed

Nanostructures are known to be exquisitely sensitive to the chemical environment and offer ultra-high sensitivity for gas-sensing. However, the fabrication and operation of devices that use individual nanostructures for sensing is complex, expensive and suffers from poor reliability due to contamination and large variability from sample-to-sample. By contrast, conventional solid-state and conducting-polymer sensors offer excellent reliability but suffer from reduced sensitivity at room-temperature. Here we report a macro graphene foam-like three-dimensional network which combines the best of both worlds. The walls of the foam are comprised of few-layer graphene sheets resulting in high sensitivity; we demonstrate parts-per-million level detection of NH(3) and NO(2) in air at room-temperature. Further, the foam is a mechanically robust and flexible macro-scale network that is easy to contact (without Lithography) and can rival the durability and affordability of traditional sensors. Moreover, Joule-heating expels chemisorbed molecules from the foam's surface leading to fully-reversible and low-power operation. PMID:22355681

Yavari, Fazel; Chen, Zongping; Thomas, Abhay V; Ren, Wencai; Cheng, Hui-Ming; Koratkar, Nikhil

2011-11-23

406

High Sensitivity Gas Detection Using a Macroscopic Three-Dimensional Graphene Foam Network  

NASA Astrophysics Data System (ADS)

Nanostructures are known to be exquisitely sensitive to the chemical environment and offer ultra-high sensitivity for gas-sensing. However, the fabrication and operation of devices that use individual nanostructures for sensing is complex, expensive and suffers from poor reliability due to contamination and large variability from sample-to-sample. By contrast, conventional solid-state and conducting-polymer sensors offer excellent reliability but suffer from reduced sensitivity at room-temperature. Here we report a macro graphene foam-like three-dimensional network which combines the best of both worlds. The walls of the foam are comprised of few-layer graphene sheets resulting in high sensitivity; we demonstrate parts-per-million level detection of NH3 and NO2 in air at room-temperature. Further, the foam is a mechanically robust and flexible macro-scale network that is easy to contact (without Lithography) and can rival the durability and affordability of traditional sensors. Moreover, Joule-heating expels chemisorbed molecules from the foam's surface leading to fully-reversible and low-power operation.

Yavari, Fazel; Chen, Zongping; Thomas, Abhay V.; Ren, Wencai; Cheng, Hui-Ming; Koratkar, Nikhil

2011-11-01

407

Development of a high sensitivity, nested Q-PCR assay for mouse and human aromatase  

PubMed Central

Measurement of breast tissue estradiol levels could provide a powerful method to predict the risk of developing breast cancer but obtaining sufficient amounts of tissue from women is difficult from a practical standpoint. Assessment of aromatase in ductal lavage fluid or fine needle aspirates from breast might provide a surrogate marker for tissue estrogen levels but highly sensitive methods would be required. These considerations prompted us to develop an ultra-sensitive, “nested” PCR assay for aromatase which is up to one million fold more sensitive than standard PCR methods. We initially validated this assay using multiple tissues from the aromatase transgenic mouse and found that coefficients of variation for measurement of replicate samples averaged less than 5%. We demonstrated a 60-fold enhancement in aromatase message in the transgenic versus the wild type mouse breast but surprisingly, levels in the transgenic animals were highly variable, ranging from 0.4 to 27 relative units. The variability of aromatase expression in the transgenic breast did not correlate with the degree of breast development and did not appear to relate to hormonal manipulation of the MMTV promoter but probably related to lack of exhaustive inbreeding and mixed zygocity of transgenic animals. Extensive validation in mouse tissues provided confidence regarding the assay in human tissues, since nearly identical methods were used. The human assay was sufficiently sensitive to detect aromatase in a single human JAR (choriocarcinoma) cell, in all breast biopsies measured, and in 7/23 ductal lavage fluids.

Liu, Giujian; Wu, Yu-sheen; Brenin, David; Yue, Wei; Aiyar, Sarah; Gompel, Anne; Wang, Ji-Ping; Tekmal, Rajeshwar Rao; Santen, Richard J.

2008-01-01

408

Highly sensitive measurements of PNA-DNA hybridization using oxide-etched silicon nanowire biosensors.  

PubMed

The highly sensitive and sequence-specific detection of single-stranded oligonucleotides using nonoxidized silicon nanowires (SiNWs) is demonstrated. To maximize device sensitivity, the surface of the SiNWs was functionalized with a densely packed organic monolayer via hydrosilylation, subsequently immobilized with peptide nucleic acid (PNA) capable of recognizing the label-free complementary target DNA. Because of the selective functionalization of the SiNWs, binding competition between the nanowire and the underlying oxide is avoided. Transmission electron microscopy was conducted to clearly differentiate the SiNW surface before and after removal of SiO(2). Fluorescence microscopy was used to further realize the selectivity of the oxide-etched chemistry on the SiNWs and sequence specificity of PNA-DNA hybridization. The concentration-dependent resistance change measurements upon hybridization of PNA-DNA show that detection limit down to 10fM can be obtained. The SiNW devices also reveal the capability of an obvious discrimination against mismatched sequences. Among several efforts being made to improve detection sensitivity, this work addresses one significant issue regarding surface functionalization which enables highly sensitive biomolecular sensing with SiNWs. PMID:18356037

Zhang, Guo-Jun; Chua, Jay Huiyi; Chee, Ru-Ern; Agarwal, Ajay; Wong, She Mein; Buddharaju, Kavitha D; Balasubramanian, N

2008-02-13

409

Highly-sensitive and label-free indium phosphide biosensor for early phytopathogen diagnosis.  

PubMed

The development of highly-sensitive and label-free operating semiconductor-based, biomaterial detecting sensors has important applications in areas such as environmental science, biomedical research and medical diagnostics. In the present study, we developed an Indium Phosphide (InP) semiconductor-based resistive biosensor using the change of its electronic properties upon biomaterial adsorption as sensing element. To detect biomaterial at low concentrations, the procedure of functionalization and covalent biomolecule immobilization was also optimized to guarantee high molecule density and high reproducibility which are prerequisite for reliable results. The characterization, such as biomolecular conjugation efficiency, detection concentration limits, receptor:ligand specificity and concentration detection range was analyzed by using three different biological systems: i) synthetic dsDNA and two phytopathogenic diseases, ii) the severe CB-form of Citrus Tristeza Virus (CTV) and iii) Xylella fastidiosa, both causing great economic loss worldwide. The experimental results show a sensitivity of 1 pM for specific ssDNA detection and about 2 nM for the specific detection of surface proteins of CTV and X. fastidiosa phytopathogens. A brief comparison with other semiconductor based biosensors and other methodological approaches is discussed and confirms the high sensitivity and reproducibility of our InP based biosensor which could be suitable for reliable early infection diagnosis in environmental and life sciences. PMID:22538056

Moreau, Alberto L D; Janissen, Richard; Santos, Clelton A; Peroni, Luis A; Stach-Machado, Dagmar R; de Souza, Alessandra A; de Souza, Anete P; Cotta, Mônica A

2012-04-06

410

Microstructural effects on ignition sensitivity in Ni/Al systems subjected to high strain rate impacts  

NASA Astrophysics Data System (ADS)

The effect of microstructural refinement on the sensitivity of the Ni/Al (1:1 mol%) system to ignition via high strain rate impacts is investigated. The tested microstructures include compacts of irregularly convoluted lamellar structures with nanometric features created through high-energy ball milling (HEBM) of micron size Ni/Al powders and compacts of nanometric Ni and Al powders. The test materials were subjected to high strain rate impacts through Asay shear experiments powered by a light gas gun. Muzzle velocities up to 1.1 km/s were used. It was found that the nanometric powder exhibited a greater sensitivity to ignition via impact than the HEBM material, despite greater thermal sensitivity of the HEBM. A previously unseen fast reaction mode where the reaction front traveled at the speed of the input stress wave was also observed in the nanometric mixtures at high muzzle energies. This fast mode is considered to be a mechanically induced thermal explosion mode dependent on the magnitude of the traveling stress wave, rather than a self-propagating detonation, since its propagation rate decreases rapidly across the sample. A similar mode is not exhibited by HEBM samples, although local, nonpropagating reaction zones shear bands formed during the impact event are observed.

Reeves, Robert V.; Mukasyan, Alexander S.; Son, Steven

2012-03-01

411

Microstructural effects on ignition sensitivity in Ni/Al systems subjected to high strain rate impacts  

NASA Astrophysics Data System (ADS)

The effect of microstructural refinement on the sensitivity of the Ni/Al (1:1 at%) system to ignition via high strain rate impacts is investigated. The tested microstructures include compacts of irregularly convoluted lamellar structures with nanometric features created through high-energy ball milling (HEBM) of micron size Ni/Al powders and compacts of nanometric Ni and Al powders. The test materials were subjected to high strain rate impacts through Asay shear experiments powered by a light gas gun. Muzzle velocities up to 1.1 km/s were used. It was found that the nanometric powder exhibited a greater sensitivity to ignition via impact than the HEBM material, despite greater thermal sensitivity of the HEBM. A previously unseen fast reaction mode where the reaction front traveled at the speed of the input stress wave was also observed in the nanometric mixtures at high muzzle energies. This fast mode is considered to be a mechanically induced thermal explosion mode dependent on the magnitude of the traveling stress wave, rather than a self-propagating detonation, since its propagation rate decreases rapidly across the sample. A similar mode is not exhibited by HEBM samples, although local, nonpropagating reaction zones occur in shear bands formed during the impact event.

Reeves, Robert; Mukasyan, Alexander; Son, Steven

2011-06-01

412

Highly sensitive, patternable organic films at the nanoscale made by bottom-up assembly.  

PubMed

Nanoscale patterning of organic thin films is of great interest for next-generation technologies. To keep pace with the demands of state-of-the-art lithography, both the sensitivity and resolution of the patternable thin films need to be improved. Here we report a highly sensitive polyurea film grown by bottom-up assembly via the molecular layer deposition (MLD) technique, which allows for high-resolution patterning at the nanoscale. The MLD process used in this work provides an exceptionally high degree of control over the film thickness and composition and also offers high coating conformality. The polyurea film was formed by urea coupling reactions between 1,4-diisocyanatobutane and 2,2'-(propane-2,2-diyldioxy)diethanamine precursors and deposited in a layer-by-layer fashion. Acid-labile ketal groups were incorporated into the backbone of the polymer chains to ensure chemically amplified cleaving reactions when combined with photoacid, which was generated by electron-beam activation of triphenylsulfonium triflate soaked into the polyurea film. With electron-beam lithography, sub-100 ?C/cm(2) sensitivity and sub-100 nm resolution were demonstrated using this new bottom-up assembly approach to resist fabrication. PMID:23594160

Zhou, Han; Blackwell, James M; Lee, Han-Bo-Ram; Bent, Stacey F

2013-04-17

413

Ethanol Sensitivity in High Drinking in the Dark Selectively Bred Mice  

PubMed Central

Background Mouse lines are being selectively bred in replicate for high blood ethanol concentrations (BECs) achieved after a short period of ethanol drinking early in the circadian dark phase. High Drinking in the Dark -1 (HDID-1) mice were in selected generation S18, and the replicate HDID-2 line in generation S11. Methods To determine other traits genetically correlated with high DID, we compared naive animals from both lines with the unselected, segregating progenitor stock, HS/Npt. Differences between HDID-1 and HS would imply commonality of genetic influences on DID and these traits. Results HDID-1 showed less basal activity, greater ethanol stimulated activity and greater sensitivity to ethanol-induced foot slips than HS. They showed lesser sensitivity to acute ethanol hypothermia and longer duration loss of righting reflex (LORR) than HS. HDID-1 and control HS lines did not differ in sensitivity on two measures of intoxication, the balance beam and the accelerating rotarod. None of the acute response results could be explained by differences in ethanol metabolism. HDID-2 mice differed from HS on some, but not all of the above responses. Conclusions These results show that some ethanol responses share common genetic control with reaching high BECs after DID, a finding consistent with other data regarding genetic contributions to ethanol responses.

Crabbe, John C.; Kruse, Lauren C.; Colville, Alexandre M.; Cameron, Andy J.; Spence, Stephanie E.; Schlumbohm, Jason P.; Huang, Lawrence C.; Metten, Pamela

2012-01-01

414

PARP inhibition sensitizes childhood high grade glioma, medulloblastoma and ependymoma to radiation.  

PubMed

Poly ADP-ribose polymerase (PARP) is a protein involved in single strand break repair. Recently, PARP inhibitors have shown considerable promise in the treatment of several cancers, both in monotherapy and in combination with cytotoxic agents. Synthetic lethal action of PARP inhibitors has been observed in tumors with mutations in double strand break repair pathways. In addition, PARP inhibition potentially enhances sensitivity of tumor cells to DNA damaging agents, including radiotherapy. Aim of this study is to determine the radiosensitizing properties of the PARP inhibitor Olaparib in childhood medulloblastoma, ependymoma and high grade glioma (HGG). Increased PARP1 expression was observed in medulloblastoma, ependymoma and HGG, as compared to non-neoplastic brain tissue. Pediatric high grade glioma, medulloblastoma and ependymoma gene expression profiling revealed that high PARP1 expression is associated with poor prognosis. Cell growth inhibition assays with Olaparib resulted in differential sensitivity, with IC50 values ranging from 1.4 to 8.4 µM, irrespective of tumor type and PARP1 protein expression. Sensitization to radiation was observed in medulloblastoma, ependymoma and HGG cell lines with subcytotoxic concentrations of Olaparib, which coincided with persistence of double strand breaks. Combining PARP inhibitors with radiotherapy in clinical studies in childhood high grade brain tumors may improve therapeutic outcome. PMID:22184287

van Vuurden, Dannis G; Hulleman, Esther; Meijer, Olga L M; Wedekind, Laurine E; Kool, Marcel; Witt, Hendrik; Vandertop, Peter W; Würdinger, Thomas; Noske, David P; Kaspers, Gertjan J L; Cloos, Jacqueline

2011-12-01

415

PARP inhibition sensitizes childhood high grade glioma, medulloblastoma and ependymoma to radiation  

PubMed Central

Poly ADP-ribose polymerase (PARP) is a protein involved in single strand break repair. Recently, PARP inhibitors have shown considerable promise in the treatment of several cancers, both in monotherapy and in combination with cytotoxic agents. Synthetic lethal action of PARP inhibitors has been observed in tumors with mutations in double strand break repair pathways. In addition, PARP inhibition potentially enhances sensitivity of tumor cells to DNA damaging agents, including radiotherapy. Aim of this study is to determine the radiosensitizing properties of the PARP inhibitor Olaparib in childhood medulloblastoma, ependymoma and high grade glioma (HGG). Increased PARP1 expression was observed in medulloblastoma, ependymoma and HGG, as compared to non-neoplastic brain tissue. Pediatric high grade glioma, medulloblastoma and ependymoma gene expression profiling revealed that high PARP1 expression is associated with poor prognosis. Cell growth inhibition assays with Olaparib resulted in differential sensitivity, with IC50 values ranging from 1.4 to 8.4 ?M, irrespective of tumor type and PARP1 protein expression. Sensitization to radiation was observed in medulloblastoma, ependymoma and HGG cell lines with subcytotoxic concentrations of Olaparib, which coincided with persistence of double strand breaks. Combining PARP inhibitors with radiotherapy in clinical studies in childhood high grade brain tumors may improve therapeutic outcome.

van Vuurden, Dannis G.; Hulleman, Esther; Meijer, Olga L.M.; Wedekind, Laurine E.; Kool, Marcel; Witt, Hendrik; Vandertop, Peter W. Peter; Wurdinger, Thomas; Noske, David P.; Kaspers, Gertjan J.L.; Cloos, Jacqueline

2011-01-01

416

Sensitive and selective tumor imaging with novel and highly activatable fluorescence strategies  

NASA Astrophysics Data System (ADS)

Nowadays, several tumor imaging modalities such as MRI, PET and fluorescence imaging techniques have been extensively investigated. One of the central problems associated with these conventional tumor-targeted imaging methods, however, is the fact that the signal contrast between tumor and surrounding tissues relies on the efficient targeting to the tumor and the rapid sequestration or excretion of unbound agent. Among these modalities, only fluorescence imaging technique has a significant feature, in that great signal activation could be achieved which potentially leads to the selective imaging of cancer with higher tumor-to-background ratio. In this symposium, I will present some examples of fluorescence cancer imaging based on highly activatable strategies with using precisely designed novel fluorescence probes. Recently, we developed highly sensitive fluorescence probes for ?-galactosidase which is applicable for living cell system. By utilizing these probes, we could establish a novel and highly activatable strategy for sensitive and selective optical imaging of imbedded tumor in the peritoneum. We took a two step procedure in that a lectin is used to localize ?-galactosidase to cancer cells as an activating enzyme, and subsequent administration of a highly-sensitive fluorescence probe for the enzyme have afforded remarkable fluorescence activation selectively in tumor mass. Since the tumor-targeted enzyme can catalyze numerous substrate turnovers, a great number of fluorescent molecules could be produced and hence the rapid and sensitive detection of tumor in vivo with high tumor-to-background ratio could be achieved. Moreover, the consequent close-up investigation using fluorescence microscopy revealed that cancer microfoci as small as 200 ?m could be successfully visualized.

Urano, Yasuteru

2008-03-01

417

Using satellites to investigate the sensitivity of longwave downward radiation to water vapor at high elevations  

NASA Astrophysics Data System (ADS)

Many studies suggest that high-elevation regions may be among the most sensitive to future climate change. However, in situ observations in these often remote locations are too sparse to determine the feedbacks responsible for enhanced warming rates. One of these feedbacks is associated with the sensitivity of longwave downward radiation (LDR) to changes in water vapor, with the sensitivity being particularly large in many high-elevation regions where the average water vapor is often low. We show that satellite retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Clouds and the Earth's Radiant Energy System (CERES) can be used to expand the current ground-based observational database and that the monthly averaged clear-sky satellite estimates of humidity and LDR are in good agreement with the well-instrumented Center for Snow and Avalanche Studies ground-based site in the southwestern Colorado Rocky Mountains. The relationship between MODIS-retrieved precipitable water vapor and surface specific humidity across the contiguous United States was found to be similar to that previously found for the Alps. More important, we show that satellites capture the nonlinear relationship between LDR and water vapor and confirm that LDR is especially sensitive to changes in water vapor at high elevations in several midlatitude mountain ranges. Because the global population depends on adequate fresh water, much of which has its source in high mountains, it is critically important to understand how climate will change there. We demonstrate that satellites can be used to investigate these feedbacks in high-elevation regions where the coverage of surface-based observations is insufficient to do so.

Naud, Catherine M.; Miller, James R.; Landry, Chris

2012-03-01

418

Robust emergent climate phenomena associated with the high-sensitivity tail.  

SciTech Connect

Because the potential effects of climate change are more severe than had previously been thought, increasing focus on uncertainty quantification is required for risk assessment needed by policy makers. Current scientific efforts focus almost exclusively on establishing best estimates of future climate change. However, the greatest consequences occur in the extreme tail of the probability density functions for climate sensitivity (the 'high-sensitivity tail'). To this end, we are exploring the impacts of newly postulated, highly uncertain, but high-consequence physical mechanisms to better establish the climate change risk. We define consequence in terms of dramatic change in physical conditions and in the resulting socioeconomic impact (hence, risk) on populations. Although we are developing generally applicable risk assessment methods, we have focused our initial efforts on uncertainty and risk analyses for the Arctic region. Instead of focusing on best estimates, requiring many years of model parameterization development and evaluation, we are focusing on robust emergent phenomena (those that are not necessarily intuitive and are insensitive to assumptions, subgrid-parameterizations, and tunings). For many physical systems, under-resolved models fail to generate such phenomena, which only develop when model resolution is sufficiently high. Our ultimate goal is to discover the patterns of emergent climate precursors (those that cannot be predicted with lower-resolution models) that can be used as a 'sensitivity fingerprint' and make recommendations for a climate early warning system that would use satellites and sensor arrays to look for the various predicted high-sensitivity signatures. Our initial simulations are focused on the Arctic region, where underpredicted phenomena such as rapid loss of sea ice are already emerging, and because of major geopolitical implications associated with increasing Arctic accessibility to natural resources, shipping routes, and strategic locations. We anticipate that regional climate will be strongly influenced by feedbacks associated with a seasonally ice-free Arctic, but with unknown emergent phenomena.

Backus, George A.; Levy, Michael Nathan; Boslough, Mark Bruce Elrick

2010-12-01

419

ZnO-nanowires modified polypyrrole films as highly selective and sensitive chlorine sensors  

NASA Astrophysics Data System (ADS)

Room temperature sensing characteristics of the polypyrrole (PPy) films modified with different weight percentages of ZnO nanowires (ZnO-NWs) have been studied for various oxidizing (NO2 and Cl2) as well as reducing (H2S, NH3, CH4, and CO) gases. We demonstrate that ZnO-NW (50 wt %):PPy composite films are highly selective to Cl2 along with high-sensitivity (40 at 10 ppm), fast-response (55 s), and highly reproducible response curves. It has been shown that negatively charged O2- surfaces of ZnO-NW transfer electrons to PPy, making it in a highly reduced form. A strong localization of charge carriers in the reduced PPy makes composite film highly resistive (>1010 ? cm) as well insensitive to interaction with most of the gases except Cl2. Cl2 being highly oxidizing gas interacts with composite films and causes a sharp reduction in its resistivity.

Joshi, Aditee; Aswal, D. K.; Gupta, S. K.; Yakhmi, J. V.; Gangal, S. A.

2009-03-01

420

A high resolution and high sensitivity proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS)  

Microsoft Academic Search

Proton-transfer-reaction mass spectrometry (PTR-MS) developed about 10 years ago is used today in a wide range of scientific and technical fields allowing real-time on-line measurements of volatile organic compounds in air with a high sensitivity and a fast response time. Most instruments employed so far use quadrupole filters to analyze product ions generated in the reaction drift tube. Due to

A. Jordan; S. Haidacher; G. Hanel; E. Hartungen; L. Märk; H. Seehauser; R. Schottkowsky; P. Sulzer; T. D. Märk

2009-01-01

421

High levels of high sensitivity C-reactive protein predict the progression of chronic rheumatic mitral stenosis  

Microsoft Academic Search

Background High sensitive C-Reactive Protein (hs-CRP) predicts morbidity and mortality in various clinical conditions. The effect of\\u000a hsCRP on progression of chronic rheumatic mitral stenosis (CRMS) has not been demonstrated. Methods and results A total of 132 patients with CRMS (95 female, 37 male) and 145 control (100 female, 45 male) were included in the study.\\u000a Baseline clinical, echocardiographic, hematologic

Omer Alyan; Fatma Metin; Fehmi Kacmaz; Ozcan Ozdemir; Orhan Maden; Serkan Topaloglu; Ahmet Duran Demir; Zulkuf Karahan; Aziz Karadede; Erdogan Ilkay

2009-01-01

422

Development of a high-count-rate neutron detector with position sensitivity and high efficiency  

SciTech Connect

While the neutron scattering community is bombarded with hints of new technologies that may deliver detectors with high-count-rate capability, high efficiency, gamma-ray insensitivity, and high resolution across large areas, only the time-tested, gas-filled {sup 3}He and scintillation detectors are in widespread use. Future spallation sources with higher fluxes simply must exploit some of the advanced detector schemes that are as yet unproved as production systems. Technologies indicating promise as neutron detectors include pixel arrays of amorphous silicon, silicon microstrips, microstrips with gas, and new scintillation materials. This project sought to study the competing neutron detector technologies and determine which or what combination will lead to a production detector system well suited for use at a high-intensity neutron scattering source.

Nelson, R.; Sandoval, J.

1996-10-01

423

Single-photon camera for high-sensitivity high-speed applications  

Microsoft Academic Search

We present a high-speed Single-Photon Camera for demanding applications in biology, astrophysics, telecommunications, 3D imaging and security surveillance. The camera is based on a 32-by-32 array of \\

Fabrizio Guerrieri; Simone Tisa; Alberto Tosi; Franco Zappa

2010-01-01

424

High-sensitivity monitoring of micromechanical vibration using optical whispering gallery mode resonators  

NASA Astrophysics Data System (ADS)

The inherent coupling of optical and mechanical modes in high finesse optical microresonators provides a natural, highly sensitive transduction mechanism for micromechanical vibration. Using homodyne and polarization spectroscopy techniques, we achieve shot-noise limited displacement sensitivities of 10^{-19}\\,m\\,Hz^{-1/2} . In an unprecedented manner, this enables the detection and study of a variety of mechanical modes, which are identified as radial breathing, flexural and torsional modes using three-dimensional finite element modeling. Furthermore, a broadband equivalent displacement noise is measured and found to agree well with models for thermorefractive noise in silica dielectric cavities. Implications for ground-state cooling, displacement sensing and Kerr squeezing are discussed.

Schliesser, A.; Anetsberger, G.; Rivière, R.; Arcizet, O.; Kippenberg, T. J.

2008-09-01

425

Quartz crystal microbalance-based system for high-sensitivity differential sputter yield measurements  

NASA Astrophysics Data System (ADS)

We present a quartz crystal microbalance-based system for high sensitivity differential sputter yield measurements of different target materials due to ion bombardment. The differential sputter yields can be integrated to find total yields. Possible ion beam conditions include ion energies in the range of 30-350 eV and incidence angles of 0°-70° from normal. A four-grid ion optics system is used to achieve a collimated ion beam at low energy (<100 eV) and a two-grid ion optics is used for higher energies (up to 750 eV). A complementary weight loss approach is also used to measure total sputter yields. Validation experiments are presented that confirm high sensitivity and accuracy of sputter yield measurements.

Rubin, B.; Topper, J. L.; Farnell, C. C.; Yalin, A. P.

2009-10-01

426

High Sensitivity Detection of ATP Using Bioluminescence at An Optical Fiber End  

NASA Astrophysics Data System (ADS)

We investigated the sensitivity of ATP detection based on bioluminescence at an optical fiber end where luciferase molecules were immobilized via silica-binding protein molecules. Luminescence was detected by an avalanche photo diode (APD), with coupling optics to make full use of the merit of compactness, high quantum efficiency and low noise of the APD. The core diameter and the numerical aperture of the optical fiber, as well as the design of the coupling optics, were optimized so as to realize high photon-collection efficiency. A detection limit of about 10-10 M was obtained, which corresponds to 10-15 mol of ATP. A rough estimation shows that the photon count rate is still two orders of magnitude lower than that limited by diffusion or reaction processes, implying a possibility of further improvement of the sensitivity.

Iinuma, Masataka; Ushio, Yasuaki; Kuroda, Akio; Kadoya, Yutaka

427

High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry  

SciTech Connect

We describe a setup for the resonance frequency measurement of individual microcantilevers. The setup displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The high sensitivity to specimen vibrations is achieved by the combination of optical Fabry-Perot interferometry and narrow band RF detection. Wave fronts reflected on the specimen and on the fiber tip end face interfere, thus no reference plane on the specimen is needed, as demonstrated with the example of freestanding silicon nitride micro-cantilevers. The resulting system is integrated in a DB-235 dual beam FIB system, thereby allowing the measurement of micro-cantilever responses during observation in SEM mode. The FIB was used to modify the optical fiber tip. At this point of our RF system development, the microcantilevers used to characterize the detector were not modified in situ.

Duden, Thomas; Radmilovic, Velimir

2009-03-04

428

Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties  

DOEpatents

An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

Pipino, Andrew Charles Rule (Gaithersburg, MD)

1999-11-16