Synthesis of 4,19-disubstituted derivatives of DOC. Radioreceptor assay of some corticosteroid derivatives in human mononuclear leukocytes.

PubMed

Harnik, M; Kashman, Y; Cojocaru, M; Bauer, H; Laux, M; Lewicka, S; Vecsei, P

1990-10-01

Several new 4,19-substituted steroids and previously synthesized corticosteroids were assayed for affinity to type 1 receptors in human mononuclear leukocytes. 11 beta,19-epoxy-4,21-dihydroxypregn-4-ene-3,20-dione (2) was hydrogenated with Pd-C to yield a mixture of all four dihydro derivatives 5, accompanied by 4,21-diacetoxy-11 beta,19-epoxy-3-hydroxypregnan-20-one (6) and 21-acetoxy-11 beta,19-epoxy-4-hydroxypregnane-3,20-dione (7). With hot acetic + p-toluenesulfonic acid 5 underwent rearrangement to 21-acetoxy-11 beta,19-epoxypregn-5-ene-4,20-dione (8) Pd-C hydrogenation of 3,21-diacetoxy-5 beta,19-cyclopregna-2,9(11)-diene-4,20-dione (10) gave 3,21-diacetoxy-5 beta,19-cyclopregn-5-ene-4,20-dione (11) and the 9,11-dihydro derivative of the latter. Treatment of 10 with warm HCl furnished 19-chloro-4,21-dihydroxypregna-4,9(11)-diene-3,20-dione (13). Pd-C hydrogenation of its diacetate 14 afforded the 4,5-dihydro derivative 18, 19-chloro-21-acetoxypregn-9(11)-en-20-one (15), its 4-acetoxy derivative 16 and the 3,4-diacetoxy derivative 17. When tested in a radioreceptor assay in human mononuclear leukocytes the synthesized compounds showed only low relative binding affinities (RBA) to type 1 receptor, the highest being 0.72% for 13 (aldosterone = 100%). For comparison, other RBA in this system were: 19-noraldosterone, 20%; 18-deoxyaldosterone, 5.8%; 18-deoxy-19-noraldosterone, 4.7%; 18,21-anhydroaldosterone, 0.37%; 17-isoaldosterone, 7.6% and apoaldosterone, 4.3%

Concomitant alteration in number and affinity of P2X and muscarinic receptors are associated with bladder dysfunction in early stage of diabetic rats.

PubMed

Yoshizawa, Tsuyoshi; Hayashi, Yukio; Yoshida, Akira; Yoshida, Shohei; Ito, Yoshihiko; Yamaguchi, Kenya; Yamada, Shizuo; Takahashi, Satoru

2018-03-01

To investigate time course of bladder dysfunction and concurrent changes in number and affinity of the muscarinic and P 2 X receptor in the early stage of streptozotocin (STZ)-induced diabetic rats. Diabetic rats were prepared by the intraperitoneal injection of 50 mg/kg of STZ to 7-week-old female Wistar rats. We performed recording of 24-h voiding behavior and cystometry at 1, 4, 8, and 12 weeks after the induction of diabetes. A muscle strip experiments with electrical field stimulation (EFS), carbachol, and α,β-methylene adenosine 5'-triphosphate (α,β-MeATP) were also performed at the same time-points. Additionally, concurrent changes in number and affinity of bladder muscarinic and P 2 X receptor were measured by a radioreceptor assay using [N-methyl- 3 H] scopolamine methyl chloride ([ 3 H]NMS) and α,β-methylene-ATP (2,8- 3 H) tetrasodium salt ([ 3 H]α,β-MeATP). In STZ-induced diabetic rats, polydipsic polyuric pollakiuria were noted on recording of 24-h voiding behavior from early stage. Also, the residual urine volume markedly increased in diabetic rats on cystometry. In the muscle strip experiment, the detrusor contractions induced by EFS, carbachol, and α,β-MeATP were enhanced in STZ-induced diabetic rats. Based on the radioreceptor assay, the maximum number of sites (Bmax) for the specific binding of [ 3 H]NMS and [ 3 H]α,β-MeATP was concurrently increased in the bladder from diabetic rats. Increased bladder contractility is found in early stage of diabetic rats. Then, bladder dysfunction is associated with increased number of muscarinic and P 2 X receptors in STZ-induced diabetic rats.

beta-endorphin: synthesis of analogs with extension at the carboxyl terminus with high radioreceptor binding activity.

PubMed

Yamashiro, D; Ferrara, P; Li, C H

1980-07-01

Four analogs of human beta-endorphin (beta h-EP) have been synthesized: [Gly31]-Beta h-EP-Gly-NH2, [CH3(CH2)4NH231]-beta h-EP, [Gly31]-beta h-EP-Gly-Gly-NH2, and [Gln8, Gly31]-betah-EP-Gly-Gly-NH2. All are more active than beta h-EP in an opiate receptor binding assay. Stepwise extension at the COOH-terminus shows a progressive increase in binding activity. The last analog, which combines extension at the COOH-terminus with elimination of the remaining anionic charge in beta h-EP, is nine times more active than the parent molecule.

Synthesis of tritium labelled endomorphin II and its stability in the radioreceptor assay

NASA Astrophysics Data System (ADS)

Tömböly, Cs.; Spetea, M.; Borsodi, A.; Tóth, G.

1999-01-01

Endomorphine I (Tyr-Pro-Trp-Phe-NH2) and endomorphin II (Tyr-Pro-Phe-Phe-NH2) are recently isolated neuropeptides. They have the highest specificity and affinity for the μ-opiate receptor among all the endogenous substances so far described, and they may be natural ligands for this receptor [1]. We prepared the [3H] endomorphin II with high specific radioactivity (53.4 Ci/mmol) by catalytic dehalotritiation. The precursor [(3,5-I2)Tyr1]-endomorphin II was synthesized by solid phase peptide synthesis using Boc chemistry. Labelled endomorphin II was used to investigate its binding properties in rat brain membrane. The stability of [3H]endomorphin II toward enzymatic degradation in membrane preparation was examined by RP-HPLC and by using a radioactivity detector.

Characterization of digitalis-like factors in human plasma. Interactions with NaK-ATPase and cross-reactivity with cardiac glycoside-specific antibodies.

PubMed

Kelly, R A; O'Hara, D S; Canessa, M L; Mitch, W E; Smith, T W

1985-09-25

Much of the evidence for a physiologically important endogenous inhibitor of the sodium pump has been either contradictory or indirect. We have identified three discrete fractions in desalted deproteinized plasma from normal humans that resemble the digitalis glycosides in that they: are of low molecular weight; are resistant to acid and enzymatic proteolysis; inhibit NaK-ATPase activity; inhibit Na+ pump activity in human erythrocytes; displace [3H]ouabain bound to the enzyme; and cross-react with high-affinity polyclonal and monoclonal digoxin-specific antibodies but not with anti-ouabain or anti-digitoxin antibodies. An additional fraction cross-reacted with digoxin-specific antibodies but had no detectable activity against NaK-ATPase. The three inhibitory fractions differed from cardiac glycosides in that their concentration-effect curves in a NaK-ATPase inhibition and [3H]ouabain radioreceptor assays were steeper than unlabeled ouabain. This suggests that these inhibitors are not simple competitive ligands for binding to NaK-ATPase. In the presence of sodium, no fraction required ATP for binding to NaK-ATPase, and in the presence of potassium, only one fraction had the reduced affinity for the enzyme that is characteristic of cardiac glycosides. Unlike digitalis, all three NaK-ATPase inhibitory fractions stimulated the activity of skeletal muscle sarcoplasmic reticulum Ca-ATPase. The presence of at least three fractions in human plasma that inhibit NaK-ATPase and cross-react to a variable degree with different digoxin-specific antibody populations could explain much of the conflicting evidence for the existence of endogenous digitalis-like compounds in plasma.

Specific binding, internalization, and degradation of human neutrophil activating factor by human polymorphonuclear leukocytes

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

Besemer, J.; Hujber, A.; Kuhn, B.

1989-10-15

The interaction of {sup 125}I-labeled recombinant human neutrophil activating factor (NAF) with polymorphonuclear leukocytes (PMN) was studied by means of a radioreceptor assay. The binding was characterized by a rapid transition (t1/2 less than or equal to 1 min) from a pH 3-sensitive state at 4{degree}C to pH 3 resistance at 37{degree}C. This was not caused by internalization of NAF since pH 3-resistant bound iodinated NAF could still be exchanged by an excess of nonlabeled NAF, i.e. was dissociable. Internalized iodinated NAF was processed into trichloroacetic acid-soluble forms. Scatchard transformation of binding isotherms at 4 and 37{degree}C led to nonlinearmore » curves, a finding which is consistent with the expression of two receptor populations, one with high (KD = 11-35 pM) and the other with lower affinity (KD = 640-830 pM) at 4 degrees C. Numbers of the low affinity binding sites were approximately 34,000, and those with high affinity were 5,200/PMN when estimated at 4 degrees C. Binding of iodinated NAF to PMN was specific since it could be competed by an excess of nonlabeled NAF but not by two other activators of PMN function, formylmethionyl-leucyl-phenylalanine or human recombinant granulocyte-macrophage colony-stimulating factor. In addition to human PMN, NAF also bound specifically to two human monocytic cell lines; however, only the low affinity binding site could be detected on these cells.« less

Conformationally restricted cyclic analogues of substance P: insight into the receptor binding process.

PubMed

Darman, P S; Landis, G C; Smits, J R; Hirning, L D; Gulya, K; Yamamura, H I; Burks, T F; Hruby, V J

1985-03-15

Three new cyclic substance P analogues were prepared to examine the possible role of a pseudocyclic turn structure for receptor recognition. In the guinea pig isolated ileum [Cys5, Cys11]-SP5-11-NH2 and [Cys6, Cys11]-SP5-11-NH2 were inactive at concentrations up to 100 microM, while [Cys5, Cys6, Nle11]-SP was a weak agonist. The order of relative affinities on the rat brain radioreceptor assay was as follows: [Cys5, Cys6, Nle11]-SP greater than [Cys5, Cys11]-SP5-11-NH2 greater than [Cys6, Cys11]-SP5-11-NH2. We interpret these results to indicate that a pseudocyclic structure of the 5-11 sequence may not be an important factor involved in the receptor recognition of substance P.

[Comparison of simple pooling and bivariate model used in meta-analyses of diagnostic test accuracy published in Chinese journals].

PubMed

Huang, Yuan-sheng; Yang, Zhi-rong; Zhan, Si-yan

2015-06-18

To investigate the use of simple pooling and bivariate model in meta-analyses of diagnostic test accuracy (DTA) published in Chinese journals (January to November, 2014), compare the differences of results from these two models, and explore the impact of between-study variability of sensitivity and specificity on the differences. DTA meta-analyses were searched through Chinese Biomedical Literature Database (January to November, 2014). Details in models and data for fourfold table were extracted. Descriptive analysis was conducted to investigate the prevalence of the use of simple pooling method and bivariate model in the included literature. Data were re-analyzed with the two models respectively. Differences in the results were examined by Wilcoxon signed rank test. How the results differences were affected by between-study variability of sensitivity and specificity, expressed by I2, was explored. The 55 systematic reviews, containing 58 DTA meta-analyses, were included and 25 DTA meta-analyses were eligible for re-analysis. Simple pooling was used in 50 (90.9%) systematic reviews and bivariate model in 1 (1.8%). The remaining 4 (7.3%) articles used other models pooling sensitivity and specificity or pooled neither of them. Of the reviews simply pooling sensitivity and specificity, 41(82.0%) were at the risk of wrongly using Meta-disc software. The differences in medians of sensitivity and specificity between two models were both 0.011 (P<0.001, P=0.031 respectively). Greater differences could be found as I2 of sensitivity or specificity became larger, especially when I2>75%. Most DTA meta-analyses published in Chinese journals(January to November, 2014) combine the sensitivity and specificity by simple pooling. Meta-disc software can pool the sensitivity and specificity only through fixed-effect model, but a high proportion of authors think it can implement random-effect model. Simple pooling tends to underestimate the results compared with bivariate model. The greater the between-study variance is, the more likely the simple pooling has larger deviation. It is necessary to increase the knowledge level of statistical methods and software for meta-analyses of DTA data.

[Effect of new peptide bioregulators livagen and epitalon on enkephalin-degrading enzymes in human serum].

PubMed

Kost, N V; Sokolov, O Iu; Gabaeva, M V; Zolotarev, Iu A; Malinin, V V; Khavinson, V Kh

2003-01-01

The effect of new peptide bioregulators--Livagen (Lys-Glu-Asp-Ala) and Epitalon (Ala-Glu-Asp-Gly)--on endogenous opioid system was studied, particularly, their ability to change the activity of enkephalin-degrading enzymes from serum and interact with opioid receptors of the brain membrane fraction. Enkephalinase activity was assayed in vitro by the rate of 3H-Leu-enkephalin hydrolysis in the presence of the tested peptides. Livagen and Epitalon inhibited enkephalin-degrading enzymes from human serum. Livagen proved to be more efficient also as compared to well-known peptidase inhibitors such as puromycin, leupeptin, and D-PAM. The dose-inhibitory effect curves for Livagen and Epitalon were plotted; their IC50 equaled 20 and 500 microM, respectively. The interaction between the peptides and opioid receptors was estimated using a radioreceptor method with [3H][D-Ala2, D-Leu5]-enkephalin. No interaction was observed between the tested peptides and mu- or delta-opioid receptors of the membrane fraction from the rat brain.

Naloxone-blocked depriming effect of anxiolytic selank on apomorphine-induced behavioral manifestations of hyperfunction of dopamine system.

PubMed

Meshavkin, V K; Kost, N V; Sokolov, O Yu; Zolotarev, Yu A; Myasoedov, N F; Zozulya, A A

2006-11-01

Peptide anxiolytic selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) applied intraperitoneally in doses of 0.01, 0.1, 1.0, and 10.0 mg/kg to mice reduces behavioral manifestations of dopaminergic system induced by apomorphine in the verticalization test. This effect was comparable to that of atypical antipsychotic olanzapine in near-therapeutic doses (0.1 and 1.0 mg/kg, intraperitoneally) and was blocked with nonselective opioid receptor antagonist naloxone (10 mg/kg, intraperitoneally). Radioreceptor assay showed that selank did not displace nonselective D2-dopamine receptor antagonist (3)H-spiperone (EC50>100 microM) and delta- and micro-opioid receptor ligand 3H-DADLE (EC50>40 microM) from specific binding sites on rat brain membranes. It is hypothesized that the revealed behavioral effect of selank is mediated by its modulating effect on the endogenous opioid system and specifically, by its effect on activity of enkephalin-degrading enzymes.

Breakdown of Spatial Parallel Coding in Children's Drawing

ERIC Educational Resources Information Center

De Bruyn, Bart; Davis, Alyson

2005-01-01

When drawing real scenes or copying simple geometric figures young children are highly sensitive to parallel cues and use them effectively. However, this sensitivity can break down in surprisingly simple tasks such as copying a single line where robust directional errors occur despite the presence of parallel cues. Before we can conclude that this…

 The product of triglycerides and glucose as biomarker for screening simple steatosis and NASH in asymptomatic women.

PubMed

Simental-Mendía, Luis E; Simental-Mendía, Esteban; Rodríguez-Hernández, Heriberto; Rodríguez-Morán, Martha; Guerrero-Romero, Fernando

2016-01-01

 Introduction and aim. Given that early identification of non-alcoholic fatty liver disease (NAFLD) is an important issue for primary prevention of hepatic disease, the objectives of this study were to evaluate the efficacy of the product of triglyceride and glucose levels (TyG) for screening simple steatosis and non-alcoholic steatohepatitis (NASH) in asymptomatic women, and to compare its efficacy vs. other biomarkers for recognizing NAFLD. Asymptomatic women aged 20 to 65 years were enrolled into a cross-sectional study. The optimal values of TyG, for screening simple steatosis and NASH were established on a Receiver Operating Characteristic scatter plot; the sensitivity, specificity, and likelihood ratios of TyG index were estimated versus liver biopsy. According sensitivity and specificity, the efficacy of TyG was compared versus the well-known clinical biomarkers for recognizing NAFLD. A total of 50 asymptomatic women were enrolled. The best cutoff point of TyG for screening simple steatosis was 4.58 (sensitivity 0.94, specificity 0.69); in addition, the best cutoff point of TyG index for screening NASH was 4.59 (sensitivity 0.87, specificity 0.69). The positive and negative likelihood ratios were 3.03 and 0.08 for simple steatosis, and 2.80 and 0.18 for NASH. As compared versus SteatoTest, NashTest, Fatty liver index, and Algorithm, the TyG showed to be the best test for screening. TyG has high sensitivity and low negative likelihood ratio; as compared with other clinical biomarkers, the TyG showed to be the best test for screening simple steatosis and NASH.

A simple but highly efficient multi-formyl phenol-amine system for fluorescence detection of peroxide explosive vapour.

PubMed

Xu, Wei; Fu, Yanyan; Gao, Yixun; Yao, Junjun; Fan, Tianchi; Zhu, Defeng; He, Qingguo; Cao, Huimin; Cheng, Jiangong

2015-07-11

A simple, highly stable, sensitive and selective fluorescent system for peroxide explosives was developed via an aromatic aldehyde oxidation reaction. The high efficiency arises from its higher HOMO level and multiple H-bonding. The sensitivity is obtained to be 0.1 ppt for H2O2 and 0.2 ppb for TATP.

A Simple Experiment for Visualizing Diffusion

ERIC Educational Resources Information Center

Helseth, L. E.

2011-01-01

We propose a simple and fascinating experiment for studying diffusion in gels using a pH-sensitive dye. By doping agar with methyl red, we obtain a gel which rapidly reacts to changes in pH by changing its absorption spectrum. The pH gradients can be followed using a digital camera, and we demonstrate here that the pH-sensitive colour changes can…

The application of sensitivity analysis to models of large scale physiological systems

NASA Technical Reports Server (NTRS)

Leonard, J. I.

1974-01-01

A survey of the literature of sensitivity analysis as it applies to biological systems is reported as well as a brief development of sensitivity theory. A simple population model and a more complex thermoregulatory model illustrate the investigatory techniques and interpretation of parameter sensitivity analysis. The role of sensitivity analysis in validating and verifying models, and in identifying relative parameter influence in estimating errors in model behavior due to uncertainty in input data is presented. This analysis is valuable to the simulationist and the experimentalist in allocating resources for data collection. A method for reducing highly complex, nonlinear models to simple linear algebraic models that could be useful for making rapid, first order calculations of system behavior is presented.

Sensitive sub-Doppler nonlinear spectroscopy for hyperfine-structure analysis using simple atomizers

NASA Astrophysics Data System (ADS)

Mickadeit, Fritz K.; Kemp, Helen; Schafer, Julia; Tong, William M.

1998-05-01

Laser wave-mixing spectroscopy is presented as a sub-Doppler method that offers not only high spectral resolution, but also excellent detection sensitivity. It offers spectral resolution suitable for hyperfine structure analysis and isotope ratio measurements. In a non-planar backward- scattering four-wave mixing optical configuration, two of the three input beams counter propagate and the Doppler broadening is minimized, and hence, spectral resolution is enhanced. Since the signal is a coherent beam, optical collection is efficient and signal detection is convenient. This simple multi-photon nonlinear laser method offers un usually sensitive detection limits that are suitable for trace-concentration isotope analysis using a few different types of simple analytical atomizers. Reliable measurement of hyperfine structures allows effective determination of isotope ratios for chemical analysis.

Platelet-derived growth factor (PDGF) in neoplastic and non-neoplastic cystic lesions of the central nervous system and in the cerebrospinal fluid.

PubMed Central

Nistér, M.; Enblad, P.; Bäckström, G.; Söderman, T.; Persson, L.; Heldin, C. H.; Westermark, B.

1994-01-01

The aim of this study was to determine the concentration of PDGF in vivo in neoplastic and non-neoplastic brain lesions. Fluid from cystic lesions and cerebrospinal fluid was tested in a radioreceptor assay that detects all described PDGF isoforms. High concentration of PDGF were found in cyst fluids from several astrocytomas, one metastatic melanoma, one metastatic lung adenocarcinoma and one intracerebral abscess. The PDGF concentrations were several times higher than the levels known to be required for maximal PDGF effects on cells in vitro. PDGF could also be detected in some non-neoplastic lesions, especially one intracerebral abscess. The finding of high amounts of PDGF in neoplastic lesions strongly supports the possibility that PDGF can be a mediator of tumour and stromal cell growth and motility in vivo. Comparison of PDGF and beta-thromboglobulin concentrations in the same fluids strongly indicates that the PDGF protein is locally produced rather than a result of platelet activation and derangement of the blood-brain barrier. PMID:8180030

Simple ultrasound rules to distinguish between benign and malignant adnexal masses before surgery: prospective validation by IOTA group

PubMed Central

Ameye, Lieveke; Fischerova, Daniela; Epstein, Elisabeth; Melis, Gian Benedetto; Guerriero, Stefano; Van Holsbeke, Caroline; Savelli, Luca; Fruscio, Robert; Lissoni, Andrea Alberto; Testa, Antonia Carla; Veldman, Joan; Vergote, Ignace; Van Huffel, Sabine; Bourne, Tom; Valentin, Lil

2010-01-01

Objectives To prospectively assess the diagnostic performance of simple ultrasound rules to predict benignity/malignancy in an adnexal mass and to test the performance of the risk of malignancy index, two logistic regression models, and subjective assessment of ultrasonic findings by an experienced ultrasound examiner in adnexal masses for which the simple rules yield an inconclusive result. Design Prospective temporal and external validation of simple ultrasound rules to distinguish benign from malignant adnexal masses. The rules comprised five ultrasonic features (including shape, size, solidity, and results of colour Doppler examination) to predict a malignant tumour (M features) and five to predict a benign tumour (B features). If one or more M features were present in the absence of a B feature, the mass was classified as malignant. If one or more B features were present in the absence of an M feature, it was classified as benign. If both M features and B features were present, or if none of the features was present, the simple rules were inconclusive. Setting 19 ultrasound centres in eight countries. Participants 1938 women with an adnexal mass examined with ultrasound by the principal investigator at each centre with a standardised research protocol. Reference standard Histological classification of the excised adnexal mass as benign or malignant. Main outcome measures Diagnostic sensitivity and specificity. Results Of the 1938 patients with an adnexal mass, 1396 (72%) had benign tumours, 373 (19.2%) had primary invasive tumours, 111 (5.7%) had borderline malignant tumours, and 58 (3%) had metastatic tumours in the ovary. The simple rules yielded a conclusive result in 1501 (77%) masses, for which they resulted in a sensitivity of 92% (95% confidence interval 89% to 94%) and a specificity of 96% (94% to 97%). The corresponding sensitivity and specificity of subjective assessment were 91% (88% to 94%) and 96% (94% to 97%). In the 357 masses for which the simple rules yielded an inconclusive result and with available results of CA-125 measurements, the sensitivities were 89% (83% to 93%) for subjective assessment, 50% (42% to 58%) for the risk of malignancy index, 89% (83% to 93%) for logistic regression model 1, and 82% (75% to 87%) for logistic regression model 2; the corresponding specificities were 78% (72% to 83%), 84% (78% to 88%), 44% (38% to 51%), and 48% (42% to 55%). Use of the simple rules as a triage test and subjective assessment for those masses for which the simple rules yielded an inconclusive result gave a sensitivity of 91% (88% to 93%) and a specificity of 93% (91% to 94%), compared with a sensitivity of 90% (88% to 93%) and a specificity of 93% (91% to 94%) when subjective assessment was used in all masses. Conclusions The use of the simple rules has the potential to improve the management of women with adnexal masses. In adnexal masses for which the rules yielded an inconclusive result, subjective assessment of ultrasonic findings by an experienced ultrasound examiner was the most accurate diagnostic test; the risk of malignancy index and the two regression models were not useful. PMID:21156740

Use of Cdse/ZnS quantum dots for sensitive detection and quantification of paraquat in water samples.

PubMed

Durán, Gema M; Contento, Ana M; Ríos, Ángel

2013-11-01

Based on the highly sensitive fluorescence change of water-soluble CdSe/ZnS core-shell quantum dots (QD) by paraquat herbicide, a simple, rapid and reproducible methodology was developed to selectively determine paraquat (PQ) in water samples. The methodology enabled the use of simple pretreatment procedure based on the simple water solubilization of CdSe/ZnS QDs with hydrophilic heterobifunctional thiol ligands, such as 3-mercaptopropionic acid (3-MPA), using microwave irradiation. The resulting water-soluble QDs exhibit a strong fluorescence emission at 596 nm with a high and reproducible photostability. The proposed analytical method thus satisfies the need for a simple, sensible and rapid methodology to determine residues of paraquat in water samples, as required by the increasingly strict regulations for health protection introduced in recent years. The sensitivity of the method, expressed as detection limits, was as low as 3.0 ng L(-1). The lineal range was between 10-5×10(3) ng L(-1). RSD values in the range of 71-102% were obtained. The analytical applicability of proposed method was demonstrated by analyzing water samples from different procedence. Copyright © 2013 Elsevier B.V. All rights reserved.

Compact sensitive instrument for direct ultrasonic visualization of defects.

PubMed

Bar-Cohen, Y; Ben-Joseph, B; Harnik, E

1978-12-01

A simple ultrasonic imaging cell based on the confocal combination of a plano-concave lens and a concave spherical mirror is described. When used in conjunction with a stroboscopic schlieren visualization system, it has the main attributes of a practical nondestructive testing instrument: it is compact, relatively inexpensive, and simple to operate; its sensitivity is fair, resolution and fidelity are good; it has a fairly large field of view and a test piece can be readily scanned. The scope of its applicability is described and discussed.

Investigating the Group-Level Impact of Advanced Dual-Echo fMRI Combinations

PubMed Central

Kettinger, Ádám; Hill, Christopher; Vidnyánszky, Zoltán; Windischberger, Christian; Nagy, Zoltán

2016-01-01

Multi-echo fMRI data acquisition has been widely investigated and suggested to optimize sensitivity for detecting the BOLD signal. Several methods have also been proposed for the combination of data with different echo times. The aim of the present study was to investigate whether these advanced echo combination methods provide advantages over the simple averaging of echoes when state-of-the-art group-level random-effect analyses are performed. Both resting-state and task-based dual-echo fMRI data were collected from 27 healthy adult individuals (14 male, mean age = 25.75 years) using standard echo-planar acquisition methods at 3T. Both resting-state and task-based data were subjected to a standard image pre-processing pipeline. Subsequently the two echoes were combined as a weighted average, using four different strategies for calculating the weights: (1) simple arithmetic averaging, (2) BOLD sensitivity weighting, (3) temporal-signal-to-noise ratio weighting and (4) temporal BOLD sensitivity weighting. Our results clearly show that the simple averaging of data with the different echoes is sufficient. Advanced echo combination methods may provide advantages on a single-subject level but when considering random-effects group level statistics they provide no benefit regarding sensitivity (i.e., group-level t-values) compared to the simple echo-averaging approach. One possible reason for the lack of clear advantages may be that apart from increasing the average BOLD sensitivity at the single-subject level, the advanced weighted averaging methods also inflate the inter-subject variance. As the echo combination methods provide very similar results, the recommendation is to choose between them depending on the availability of time for collecting additional resting-state data or whether subject-level or group-level analyses are planned. PMID:28018165

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

PubMed

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

2011-07-15

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

Sonicated Diagnostic Immunoblot for Bartonellosis

PubMed Central

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

2000-01-01

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

A simple Bird Sensitivity to Oil Index as a management tool in coastal and marine areas subject to oil spills when few biological information is available.

PubMed

Romero, A F; Oliveira, M; Abessa, D M S

2018-03-01

This study sought to develop a simple index for ranking birds' environmental sensitivity to oil in which birds are used as biological indicators. The study area consisted of both the Santos Estuarine System (SES), and the Laje de Santos Marine State Park (LSMSP), located in Southeastern Brazil. Information on the bird species and their feeding and nesting behaviors were obtained from the literature and were the basis of the sensitivity index created. The SES had a higher number of species, but only about 30% were found to be highly sensitive. The LSMSP presented a much lower number of species, but all of them were considered to be highly sensitive to oil. Due to its simplicity, this index can be employed worldwide as a decision-making tool that may be integrated into other management tools, particularly when robust information on the biology of birds is lacking. Copyright © 2017 Elsevier Ltd. All rights reserved.

Highly sensitive and simple SERS substrate based on photochemically generated carbon nanotubes-gold nanorods hybrids.

PubMed

Caires, A J; Vaz, R P; Fantini, C; Ladeira, L O

2015-10-01

We report a simple and easy formation of hybrids between multi-wall carbon nanotubes and gold nanorods by one-pot in situ photochemical synthesis. Measurements of surface-enhanced Raman scattering (SERS) through the effect "coffee ring" in visible and near infrared (NIR) show high sensitivity with detection of nanomolar concentrations of aromatic dyes. The formation of nanocomposites between carbon nanotubes and gold nanorods without chemical binders simplifies the preparation. Photochemical synthesis is an advance over the techniques previously published. Copyright © 2015 Elsevier Inc. All rights reserved.

Precise Temperature Measurement for Increasing the Survival of Newborn Babies in Incubator Environments

PubMed Central

Frischer, Robert; Penhaker, Marek; Krejcar, Ondrej; Kacerovsky, Marian; Selamat, Ali

2014-01-01

Precise temperature measurement is essential in a wide range of applications in the medical environment, however the regarding the problem of temperature measurement inside a simple incubator, neither a simple nor a low cost solution have been proposed yet. Given that standard temperature sensors don't satisfy the necessary expectations, the problem is not measuring temperature, but rather achieving the desired sensitivity. In response, this paper introduces a novel hardware design as well as the implementation that increases measurement sensitivity in defined temperature intervals at low cost. PMID:25494352

Evaluation of IOTA Simple Ultrasound Rules to Distinguish Benign and Malignant Ovarian Tumours.

PubMed

Garg, Sugandha; Kaur, Amarjit; Mohi, Jaswinder Kaur; Sibia, Preet Kanwal; Kaur, Navkiran

2017-08-01

IOTA stands for International Ovarian Tumour Analysis group. Ovarian cancer is one of the common cancers in women and is diagnosed at later stage in majority. The limiting factor for early diagnosis is lack of standardized terms and procedures in gynaecological sonography. Introduction of IOTA rules has provided some consistency in defining morphological features of ovarian masses through a standardized examination technique. To evaluate the efficacy of IOTA simple ultrasound rules in distinguishing benign and malignant ovarian tumours and establishing their use as a tool in early diagnosis of ovarian malignancy. A hospital based case control prospective study was conducted. Patients with suspected ovarian pathology were evaluated using IOTA ultrasound rules and designated as benign or malignant. Findings were correlated with histopathological findings. Collected data was statistically analysed using chi-square test and kappa statistical method. Out of initial 55 patients, 50 patients were included in the final analysis who underwent surgery. IOTA simple rules were applicable in 45 out of these 50 patients (90%). The sensitivity for the detection of malignancy in cases where IOTA simple rules were applicable was 91.66% and the specificity was 84.84%. Accuracy was 86.66%. Classifying inconclusive cases as malignant, the sensitivity and specificity was 93% and 80% respectively. High level of agreement was found between USG and histopathological diagnosis with Kappa value as 0.323. IOTA simple ultrasound rules were highly sensitive and specific in predicting ovarian malignancy preoperatively yet being reproducible, easy to train and use.

Simple and sensitive analysis of blonanserin and blonanserin C in human plasma by liquid chromatography tandem mass spectrometry and its application.

PubMed

Zheng, Yunliang; Hu, Xingjiang; Liu, Jian; Wu, Guolan; Zhou, Huili; Zhu, Meixiang; Zhai, You; Wu, Lihua; Shentu, Jianzhong

2014-01-01

A highly sensitive, simple, and rapid liquid chromatography tandem mass spectrometry method to simultaneously determine blonanserin and blonanserin C in human plasma with AD-5332 as internal standard (IS) was established. A simple direct protein precipitation method was used for the sample pretreatment, and chromatographic separation was performed on a Waters XBridge C8 (4.6 × 150 mm, 3.5  μ m) column. The mobile phase consists of a mixture of 10 mM ammonium formate and 0.1% formic acid in water (A) and 0.1% formic acid in methanol (B). To quantify blonanserin, blonanserin C, and IS, multiple reaction monitoring (MRM) was performed in positive ESI mode. The calibration curve was linear in the concentration range of 0.012-5.78 ng·mL(-1) for blonanserin and 0.023-11.57 ng·mL(-1) for blonanserin C (r (2) > 0.9990). The intra- and interday precision of three quality control (QC) levels in plasma were less than 7.5%. Finally, the current simple, sensitive, and accurate LC-MS/MS method was successfully applied to investigate the pharmacokinetics of blonanserin and blonanserin C in healthy Chinese volunteers.

Simple and Sensitive Analysis of Blonanserin and Blonanserin C in Human Plasma by Liquid Chromatography Tandem Mass Spectrometry and Its Application

PubMed Central

Zheng, Yunliang; Hu, Xingjiang; Liu, Jian; Wu, Guolan; Zhou, Huili; Zhu, Meixiang; Zhai, You; Wu, Lihua; ShenTu, Jianzhong

2014-01-01

A highly sensitive, simple, and rapid liquid chromatography tandem mass spectrometry method to simultaneously determine blonanserin and blonanserin C in human plasma with AD-5332 as internal standard (IS) was established. A simple direct protein precipitation method was used for the sample pretreatment, and chromatographic separation was performed on a Waters XBridge C8 (4.6 × 150 mm, 3.5 μm) column. The mobile phase consists of a mixture of 10 mM ammonium formate and 0.1% formic acid in water (A) and 0.1% formic acid in methanol (B). To quantify blonanserin, blonanserin C, and IS, multiple reaction monitoring (MRM) was performed in positive ESI mode. The calibration curve was linear in the concentration range of 0.012–5.78 ng·mL−1 for blonanserin and 0.023–11.57 ng·mL−1 for blonanserin C (r 2 > 0.9990). The intra- and interday precision of three quality control (QC) levels in plasma were less than 7.5%. Finally, the current simple, sensitive, and accurate LC-MS/MS method was successfully applied to investigate the pharmacokinetics of blonanserin and blonanserin C in healthy Chinese volunteers. PMID:24678425

Muscarinic Receptor Binding in Rat Bladder Urothelium and Detrusor Muscle by Intravesical Solifenacin.

PubMed

Ito, Yoshihiko; Kashiwabara, Michishi; Yoshida, Akira; Hikiyama, Eriko; Onoue, Satomi; Yamada, Shizuo

2016-01-01

Solifenacin is an antimuscarinic agent used to treat symptoms of overactive bladder. Pharmacologically significant amounts of solifenacin were excreted in the urine of humans taking a clinical dose of this drug. The aim of this study is to measure muscarinic receptor binding in the bladder urothelium and detrusor muscles of rats following the intravesical instillation of solifenacin. Muscarinic receptors were measured by radioreceptor assay using [N-methyl-(3)H]scopolamine methyl chloride ([(3)H]NMS), a selective radioligand of muscarinic receptors. Solifenacin showed concentration-dependent inhibition of specific [(3)H]NMS binding in the bladder urothelium and detrusor muscle of rats, with no significant difference in Ki values or Hill coefficients between these tissues. Following the intravesical instillation of solifenacin, there was significant muscarinic receptor binding (increase in Kd for specific [(3)H]NMS binding) in the bladder urothelium and detrusor muscle of rats. Similar bladder muscarinic receptor binding was observed by the intravesical instillation of oxybutynin, but not with trospium. In conclusion, the present study has demonstrated that solifenacin binds muscarinic receptors not only in the detrusor muscle but also in the bladder urothelium with high affinity. These bladder muscarinic receptors may be significantly affected by solifenacin excreted in the urine.

Acquired neonatal thyroid disease due to TSH receptor antibodies in breast milk.

PubMed

Törnhage, C J; Grankvist, K

2006-06-01

We investigated whether thyroid receptor antibodies (TRAb) could result in transient neonatal thyroid disease by transfer through milk from mothers treated for thyrotoxicosis. To analyse whether breast milk content of TRAb in euthyroid mothers with treated thyrotoxicosis resulted in neonatal thyroid disease and whether extended breastfeeding prolonged the neonatal disease. We tested three TRAb-positive mothers and the course, treatment and outcome for their offspring with neonatal thyrotoxicosis, and six healthy and two TRAb-negative euthyroid mothers with treated thyrotoxicosis during breastfeeding. TRAb was analysed in serum and breast milk by a radioreceptor assay. TRAb in serum was detectable in all treated mothers, in one mother during her four pregnancies, resulting in all neonates requiring treatment for thyrotoxicosis. Serum TRAb concentration in neonates decreased continuously with time after birth. Breast milk TRAb was detectable in all cases but not in the controls or in TRAb-negative mothers treated for thyrotoxicosis. The calculated half-life for offspring serum and breast milk TRAb was calculated as approx. 3 weeks and 2 months, respectively. Euthyroid TRAb-positive mothers may cause transient neonatal thyroid disease which seems to be worse and more prolonged during breastfeeding as a consequence of TRAb in breast milk.

Stability of a pH-sensitive polymer matrix

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

Northrup, M.A.; Langry, K.; Angel, S.M.

1990-03-01

A ratiometric pH-sensitive fluorescent dye (hydroxypyrenetrisulfonic acid) was covalently attached to an acrylamide polymer. These pH-sensitive copolymers were either covalently bonded to the end of an optical fiber or polymerized into separate gels. Long-term, accelerated aging studies were performed on the fibers and gels in 43{degree}C distilled H{sub 2}O. The fiber-immobilized optrodes gave good pH responses for up to 2 months. The pH-sensitive gels were physically attached to optical fibers and gave very good pH responses for over one year. These physically immobilized, one-year-old, pH-sensitive copolymers provided optrodes with linear pH responses between pH 6 and 8 and resolution greatermore » than 0.25 pH unit. A simple photostability experiment on these optrodes showed that they were very photostable. The results of this study indicate that pH-sensitive copolymers in a simple optrode design can be employed as pH sensors with useful lifetimes exceeding one year. 11 refs., 6 figs.« less

Use of simple models to determine wake vortex categories for new aircraft.

DOT National Transportation Integrated Search

2015-06-22

The paper describes how to use simple models and, if needed, sensitivity analyses to determine the wake vortex categories for new aircraft. The methodology provides a tool for the regulators to assess the relative risk of introducing new aircraft int...

Analysis of Publically Available Skin Sensitization Data from REACH Registrations 2008–2014

PubMed Central

Luechtefeld, Thomas; Maertens, Alexandra; Russo, Daniel P.; Rovida, Costanza; Zhu, Hao; Hartung, Thomas

2017-01-01

Summary The public data on skin sensitization from REACH registrations already included 19,111 studies on skin sensitization in December 2014, making it the largest repository of such data so far (1,470 substances with mouse LLNA, 2,787 with GPMT, 762 with both in vivo and in vitro and 139 with only in vitro data). 21% were classified as sensitizers. The extracted skin sensitization data was analyzed to identify relationships in skin sensitization guidelines, visualize structural relationships of sensitizers, and build models to predict sensitization. A chemical with molecular weight > 500 Da is generally considered non-sensitizing owing to low bioavailability, but 49 sensitizing chemicals with a molecular weight > 500 Da were found. A chemical similarity map was produced using PubChem’s 2D Tanimoto similarity metric and Gephi force layout visualization. Nine clusters of chemicals were identified by Blondel’s module recognition algorithm revealing wide module-dependent variation. Approximately 31% of mapped chemicals are Michael’s acceptors but alone this does not imply skin sensitization. A simple sensitization model using molecular weight and five ToxTree structural alerts showed a balanced accuracy of 65.8% (specificity 80.4%, sensitivity 51.4%), demonstrating that structural alerts have information value. A simple variant of k-nearest neighbors outperformed the ToxTree approach even at 75% similarity threshold (82% balanced accuracy at 0.95 threshold). At higher thresholds, the balanced accuracy increased. Lower similarity thresholds decrease sensitivity faster than specificity. This analysis scopes the landscape of chemical skin sensitization, demonstrating the value of large public datasets for health hazard prediction. PMID:26863411

A Versatile PDMS/Paper Hybrid Microfluidic Platform for Sensitive Infectious Disease Diagnosis

PubMed Central

2015-01-01

Bacterial meningitis is a serious health concern worldwide. Given that meningitis can be fatal and many meningitis cases occurred in high-poverty areas, a simple, low-cost, highly sensitive method is in great need for immediate and early diagnosis of meningitis. Herein, we report a versatile and cost-effective polydimethylsiloxane (PDMS)/paper hybrid microfluidic device integrated with loop-mediated isothermal amplification (LAMP) for the rapid, sensitive, and instrument-free detection of the main meningitis-causing bacteria, Neisseria meningitidis (N. meningitidis). The introduction of paper into the microfluidic device for LAMP reactions enables stable test results over a much longer period of time than a paper-free microfluidic system. This hybrid system also offers versatile functions, by providing not only on-site qualitative diagnostic analysis (i.e., a yes or no answer), but also confirmatory testing and quantitative analysis in laboratory settings. The limit of detection of N. meningitidis is about 3 copies per LAMP zone within 45 min, close to single-bacterium detection sensitivity. In addition, we have achieved simple pathogenic microorganism detection without a laborious sample preparation process and without the use of centrifuges. This low-cost hybrid microfluidic system provides a simple and highly sensitive approach for fast instrument-free diagnosis of N. meningitidis in resource-limited settings. This versatile PDMS/paper microfluidic platform has great potential for the point of care (POC) diagnosis of a wide range of infectious diseases, especially for developing nations. PMID:25019330

Rules of Thumb for Depth of Investigation, Pseudo-Position and Resolution of the Electrical Resistivity Method from Analysis of the Moments of the Sensitivity Function for a Homogeneous Half-Space

NASA Astrophysics Data System (ADS)

Butler, S. L.

2017-12-01

The electrical resistivity method is now highly developed with 2D and even 3D surveys routinely performed and with available fast inversion software. However, rules of thumb, based on simple mathematical formulas, for important quantities like depth of investigation, horizontal position and resolution have not previously been available and would be useful for survey planning, preliminary interpretation and general education about the method. In this contribution, I will show that the sensitivity function for the resistivity method for a homogeneous half-space can be analyzed in terms of its first and second moments which yield simple mathematical formulas. The first moment gives the sensitivity-weighted center of an apparent resistivity measurement with the vertical center being an estimate of the depth of investigation. I will show that this depth of investigation estimate works at least as well as previous estimates based on the peak and median of the depth sensitivity function which must be calculated numerically for a general four electrode array. The vertical and horizontal first moments can also be used as pseudopositions when plotting 1, 2 and 3D pseudosections. The appropriate horizontal plotting point for a pseudosection was not previously obvious for nonsymmetric arrays. The second moments of the sensitivity function give estimates of the spatial extent of the region contributing to an apparent resistivity measurement and hence are measures of the resolution. These also have simple mathematical formulas.

Sensitivity of the ocean overturning circulation to wind and mixing: theoretical scalings and global ocean models

NASA Astrophysics Data System (ADS)

Nikurashin, Maxim; Gunn, Andrew

2017-04-01

The meridional overturning circulation (MOC) is a planetary-scale oceanic flow which is of direct importance to the climate system: it transports heat meridionally and regulates the exchange of CO2 with the atmosphere. The MOC is forced by wind and heat and freshwater fluxes at the surface and turbulent mixing in the ocean interior. A number of conceptual theories for the sensitivity of the MOC to changes in forcing have recently been developed and tested with idealized numerical models. However, the skill of the simple conceptual theories to describe the MOC simulated with higher complexity global models remains largely unknown. In this study, we present a systematic comparison of theoretical and modelled sensitivity of the MOC and associated deep ocean stratification to vertical mixing and southern hemisphere westerlies. The results show that theories that simplify the ocean into a single-basin, zonally-symmetric box are generally in a good agreement with a realistic, global ocean circulation model. Some disagreement occurs in the abyssal ocean, where complex bottom topography is not taken into account by simple theories. Distinct regimes, where the MOC has a different sensitivity to wind or mixing, as predicted by simple theories, are also clearly shown by the global ocean model. The sensitivity of the Indo-Pacific, Atlantic, and global basins is analysed separately to validate the conceptual understanding of the upper and lower overturning cells in the theory.

Effectiveness of simple control measures on methicillin-resistant Staphylococcus aureus infection status and characteristics with susceptibility patterns in a teaching hospital in Peshawar.

PubMed

Rafiq, Muhammad Salman; Rafiq, Muhammad Imran; Khan, Taimur; Rafiq, Maria; Khan, Mah Muneer

2015-09-01

To determine the effectiveness of simple control measures on the infection status and characteristics of methicillin-resistant Staphylococcus aureus including susceptibility patterns among health professionals and patients in a teaching hospital. The cross-sectional study was conducted from September 2013 to January 2014, and comprised samples collected from healthcare personnel and patients in the various units of Khyber Teaching Hospital, Peshawar. The specimens were collected before and one month after the implementation of simple control measures for outbreak prevention of methicillin-resistant Staphylococcus aureus. These were tested for culture and antimicrobial susceptibility. Data about methicillin-sensitive and methicillin-resistant Staphylococcus aureus infection, wound characteristics and susceptibility patterns was collected and effectiveness of simple control measures was determined. SPSS 20 was used for statistical analysis. Of the total 390 isolates, 180(46.2%) were Staphylococcus aureus; 77(19.7%) from healthcare personnel and 103(26.4%) from patients. Of these, 164(42.1%) were methicillin-sensitive and 16(4.1%) were methicillin-resistant. Among the patients, 38(15.1%) methicillin-sensitive and 8(3.2%) methicillin-resistant isolates were recovered from wounds or skin and soft tissues. Pus with 33(13.1%) and 4(1.6%) cases respectively was the second most common source. Among methicillin-resistant isolates, resistance to Linezolid was 0%, all were resistant to Oxacillin, Cefoxitin, Amoxicillin, Cefotaxime and Cephradine, and resistance to both Co-Amoxiclav and Ciprofloxacin was 87.5%. After one month of implementation of simple control measures, the number of methicillin-resistant cases among healthcare professionals and patients dropped from 4(2.9%) and 7(10.8%) to 1(0.7%) and 5(2.7%), respectively. Methicillin-resistant and methicillin-sensitive Staphylococcus aureus differed in their anti-microbial susceptibility profiles. Selection of antibiotics based on susceptibility and culture is needed for prevention of resistance and effective treatment. A decrease was observed in methicillin-resistant cases with implementation of control measures.

Assessment of simple colorimetric procedures to determine smoking status of diabetic subjects.

PubMed

Smith, R F; Mather, H M; Ellard, G A

1998-02-01

The performance of a simple colorimetric assay for urinary nicotine metabolites to assess smoking status in diabetic subjects (n = 251) was investigated. Several variations of the colorimetric assay and a qualitative extraction procedure were evaluated in comparison with a cotinine immunoassay as the "gold standard." Among these, the best overall performance was achieved with the qualitative test (sensitivity 95%; specificity 100%). The quantitative measurement of total nicotine metabolites performed less well (sensitivity 92%; specificity 97%) but could be improved by incorporating a blank extraction (sensitivity 98%; specificity 98%). Allowance for diuresis appeared to offer no advantage over the other methods. These results support previous findings regarding the use of these colorimetric procedures in nondiabetic subjects and, contrary to other recent observations, their performance was not impaired in diabetic patients.

Evaluation of IOTA Simple Ultrasound Rules to Distinguish Benign and Malignant Ovarian Tumours

PubMed Central

Kaur, Amarjit; Mohi, Jaswinder Kaur; Sibia, Preet Kanwal; Kaur, Navkiran

2017-01-01

Introduction IOTA stands for International Ovarian Tumour Analysis group. Ovarian cancer is one of the common cancers in women and is diagnosed at later stage in majority. The limiting factor for early diagnosis is lack of standardized terms and procedures in gynaecological sonography. Introduction of IOTA rules has provided some consistency in defining morphological features of ovarian masses through a standardized examination technique. Aim To evaluate the efficacy of IOTA simple ultrasound rules in distinguishing benign and malignant ovarian tumours and establishing their use as a tool in early diagnosis of ovarian malignancy. Materials and Methods A hospital based case control prospective study was conducted. Patients with suspected ovarian pathology were evaluated using IOTA ultrasound rules and designated as benign or malignant. Findings were correlated with histopathological findings. Collected data was statistically analysed using chi-square test and kappa statistical method. Results Out of initial 55 patients, 50 patients were included in the final analysis who underwent surgery. IOTA simple rules were applicable in 45 out of these 50 patients (90%). The sensitivity for the detection of malignancy in cases where IOTA simple rules were applicable was 91.66% and the specificity was 84.84%. Accuracy was 86.66%. Classifying inconclusive cases as malignant, the sensitivity and specificity was 93% and 80% respectively. High level of agreement was found between USG and histopathological diagnosis with Kappa value as 0.323. Conclusion IOTA simple ultrasound rules were highly sensitive and specific in predicting ovarian malignancy preoperatively yet being reproducible, easy to train and use. PMID:28969237

Low cost charged-coupled device (CCD) based detectors for Shiga toxins activity analysis

USDA-ARS?s Scientific Manuscript database

To improve food safety there is a need to develop simple, low-cost sensitive devices for detection of foodborne pathogens and their toxins. We describe a simple and relatively low-cost webcam-based detector which can be used for various optical detection modalities, including fluorescence, chemilumi...

Sensitive SERS detection of lead ions via DNAzyme based quadratic signal amplification.

PubMed

Tian, Aihua; Liu, Yu; Gao, Jian

2017-08-15

Highly sensitive detection of Pb 2+ is very necessary for water quality control, clinical toxicology, and industrial monitoring. In this work, a simple and novel DNAzyme-based SERS quadratic amplification method is developed for the detection of Pb 2+ . This strategy possesses some remarkable features compared to the conventional DNAzyme-based SERS methods, which are as follows: (i) Coupled DNAzyme-activated hybridization chain reaction (HCR) with bio barcodes; a quadratic amplification method is designed using the unique catalytic selectivity of DNAzyme. The SERS signal is significantly amplified. This method is rapid with a detection time of 2h. (ii) The problem of high background induced by excess bio barcodes is circumvented by using magnetic beads (MBs) as the carrier of signal-output products, and this sensing system is simple in design and can easily be carried out by simple mixing and incubation. Given the unique and attractive characteristics, a simple and universal strategy is designed to accomplish sensitive detection of Pb 2+ . The detection limit of Pb 2+ via SERS detection is 70 fM, with the linear range from 1.0×10 -13 M to 1.0×10 -7 M. The method can be further extended to the quantitative detection of a variety of targets by replacing the lead-responsive DNAzyme with other functional DNA. Copyright © 2017 Elsevier B.V. All rights reserved.

PC-BASED SUPERCOMPUTING FOR UNCERTAINTY AND SENSITIVITY ANALYSIS OF MODELS

EPA Science Inventory

Evaluating uncertainty and sensitivity of multimedia environmental models that integrate assessments of air, soil, sediments, groundwater, and surface water is a difficult task. It can be an enormous undertaking even for simple, single-medium models (i.e. groundwater only) descr...

Design sensitivity analysis of nonlinear structural response

NASA Technical Reports Server (NTRS)

Cardoso, J. B.; Arora, J. S.

1987-01-01

A unified theory is described of design sensitivity analysis of linear and nonlinear structures for shape, nonshape and material selection problems. The concepts of reference volume and adjoint structure are used to develop the unified viewpoint. A general formula for design sensitivity analysis is derived. Simple analytical linear and nonlinear examples are used to interpret various terms of the formula and demonstrate its use.

A simple and sensitive method for the determination of fibric acids in the liver by liquid chromatography.

PubMed

Karahashi, Minako; Fukuhara, Hiroto; Hoshina, Miki; Sakamoto, Takeshi; Yamazaki, Tohru; Mitsumoto, Atsushi; Kawashima, Yoichi; Kudo, Naomi

2014-01-01

Fibrates are used in biochemical and pharmacological studies as bioactive tools. Nevertheless, most studies have lacked information concerning the concentrations of fibric acids working inside tissues because a simple and sensitive method is not available for their quantitation. This study aimed to develop a simple and sensitive bioanalytical method for the quantitation of clofibric, bezafibric and fenofibric acids in samples of very small portions of tissues. Fibric acids were extracted into n-hexane-ethyl acetate from tissue homogenates (10 mg of liver, kidney or muscle) or serum (100 µL) and were derivatized with 4-bromomethyl-6,7-dimethoxycoumarin, followed by HPLC with fluorescence detection. These compounds were separated isocratically on a reversed phase with acetonitrile-water. Standard analytical curves were linear over the concentration range of 0.2-20 nmol/10 mg of liver. Precision and accuracy were within acceptable limits. Recovery from liver homogenates ranged from 93.03 to 112.29%. This method enabled the quantitation of fibric acids in 10 mg of liver from rats treated with clofibric acid, bezafibric acid or fenofibrate. From these analytical data, it became clear that there was no large difference in ratio of acyl-CoA oxidase 1 (Acox1) mRNA level to fibric acid content in the liver among the three fibric acids, suggesting that these three fibric acids have similar potency to increase expression of the Acox1 gene, which is a target of peroxisome proliferator-activated receptor α. Thus, the proposed method is a simple, sensitive and reliable tool for the quantitation of fibric acids working in vivo inside livers.

AN APPROACH FOR SCREENING CHOLINESTERASE INHIBITORS IN DRINKING WATER USING AN IMMOBILIZED ENZYME ASSAY

EPA Science Inventory

A simple, inexpensive and sensitive method for detecting organophosphate and carbamate insecticides is reported. Acetylcholinesterase was immobilized to PorexR Lateral-FloTM membrane material and remained active for several months at room temperature. The assay was sensitive ...

75 FR 29763 - Government-Owned Inventions; Availability for Licensing

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-27

... commercialization of results of federally-funded research and development. Foreign patent applications are filed on... patent applications. Simple, Quantitative and Highly Specific Antibody Detection of Lyme Disease... markedly out-performed the C6 ELISA test (currently the most sensitive test available, with 76% sensitivity...

The development of simple and sensitive small-molecule fluorescent probes for the detection of serum proteins after native polyacrylamide gel electrophoresis.

PubMed

Wang, Fangfang; Huang, Lingyun; Na, Na; He, Dacheng; Sun, Dezhi; Ouyang, Jin

2012-05-21

In this paper, a simple and sensitive small-molecule fluorescent probe, 2,5-dihydroxy-4'-dimethylaminochalcone (DHDMAC), was designed and synthesized for the detection of human serum proteins via hydrophobic interactions after polyacrylamide gel electrophoresis (PAGE). This probe produced lower fluorescence emission in the absence of proteins, and the emission intensity was significantly increased after the interaction with serum proteins. To demonstrate the imaging performance of this probe as a fluorescent dye, a series of experiments was conducted that included sensitivity comparison and 2D-PAGE. The results indicated that the sensitivity of DHDMAC staining is comparable to that of the most widely used fluorescent dye, SYPRO Ruby, and more protein spots (including thyroxine-binding globulin, angiotensinogen, afamin, zinc-α-2-glycoprotein and α-1-antichymotrypsin) were detected after 2D-PAGE. Therefore, DHDMAC is a good protein reporter due to its fast staining procedure, low detection limits and high resolution.

A new simple screening method for the detection of paralytic shellfish poisoning toxins

NASA Astrophysics Data System (ADS)

Cheng, Jinping; Pi, Shuaishuai; Ye, Shufeng; Gao, Haomin; Yao, Lei; Jiang, Zhenyi; Song, Yuling; Xi, Lei

2012-09-01

The current testing for paralytic shellfish poisoning (PSP) in shellfish is based on the mouse bioassay (MBA). To alleviate animal welfare concerns, we evaluated the utility of using sublethal indicators of toxicity as an alternative to measuring time to death. Live mice were injected with a PSP congener and the changes in neurotransmitter levels were measured 60, 90, and 120 min after injection. Acetylcholine (ACh) was the most sensitive marker for PSP toxicity. The changes in neurotransmitter levels were most pronounced in the blood. Thus, measurement of Ach levels in the blood may serve as a sensitive predictor for PSP that would not require sacrifice of the mice. This method was relatively simple, sensitive (less than 1 μg/kg weight, equivalent to 20 ng/mL), low maintenance, and rapid (less than 60 min).

Simple, Inexpensive, and Rapid Way to Produce Bacillus subtilis Spores for the Guthrie Bioassay

PubMed Central

Franklin, Martha L.; Clark, William A.

1981-01-01

Esculin agar has been found to be a simple, inexpensive, rapid, and reliable means to promote production of spores of inhibitor-sensitive clones of Bacillus subtilis strains ATCC 6051 and 6633 for use in the Guthrie bioassay screening tests for genetic metabolic disorders. Images PMID:6790564

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

PubMed

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

2010-03-01

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

SERS-based pesticide detection by using nanofinger sensors

NASA Astrophysics Data System (ADS)

Kim, Ansoon; Barcelo, Steven J.; Li, Zhiyong

2015-01-01

Simple, sensitive, and rapid detection of trace levels of extensively used and highly toxic pesticides are in urgent demand for public health. Surface-enhanced Raman scattering (SERS)-based sensor was designed to achieve ultrasensitive and simple pesticide sensing. We developed a portable sensor system composed of high performance and reliable gold nanofinger sensor strips and a custom-built portable Raman spectrometer. Compared to the general procedure and previously reported studies that are limited to laboratory settings, our analytical method is simple, sensitive, rapid, and cost-effective. Based on the SERS results, the chemical interaction of two pesticides, chlorpyrifos (CPF) and thiabendazole (TBZ), with gold nanofingers was studied to determine a fingerprint for each pesticide. The portable SERS-sensor system was successfully demonstrated to detect CPF and TBZ pesticides within 15 min with a detection limit of 35 ppt in drinking water and 7 ppb on apple skin, respectively.

A study on the sensitivity of self-powered neutron detectors (SPNDs)

NASA Astrophysics Data System (ADS)

Lee, Wanno; Cho, Gyuseong; Kim, Kwanghyun; Kim, Hee Joon; choi, Yuseon; Park, Moon Chu; Kim, Soongpyung

2001-08-01

Self-powered neutron detectors (SPNDs) are widely used in reactors to monitor neutron flux, while they have several advantages such as small size, and relatively simple electronics required in conjunction with those usages, they have some intrinsic problems of the low level of output current-a slow response time and the rapid change of sensitivity-that make it difficult to use for a long term. Monte Carlo simulation was used to calculate the escape probability as a function of the birth position of emitted beta particle for geometry of rhodium-based SPNDs. A simple numerical method calculated the initial generation rate of beta particles and the change of generation rate due to rhodium burnup. Using results of the simulation and the simple numerical method, the burnup profile of rhodium number density and the neutron sensitivity were calculated as a function of burnup time in reactors. This method was verified by the comparison of this and other papers, and data of YGN3.4 (Young Gwang Nuclear plant 3, 4) about the initial sensitivity. In addition, for improvement of some properties of rhodium-based SPNDs, which are currently used, a modified geometry is proposed. The proposed geometry, which is tube-type, is able to increase the initial sensitivity due to increase of the escape probability. The escape probability was calculated by changing the thickness of the insulator and compared solid-type with tube-type about each insulator thickness. The method used here can be applied to the analysis and design of other types of SPNDs.

Sensitivity enhancement of traveling wave MRI using free local resonators: an experimental demonstration.

PubMed

Zhang, Xiaoliang

2017-04-01

Traveling wave MR uses the far fields in signal excitation and reception, therefore its acquisition efficiency is low in contrast to the conventional near field magnetic resonance (MR). Here we show a simple and efficient method based on the local resonator to improving sensitivity of traveling wave MR technique. The proposed method utilizes a standalone or free local resonator to amplify the radio frequency magnetic fields in the interested target. The resonators have no wire connections to the MR system and thus can be conveniently placed to any place around imaging simples. A rectangular loop L/C resonator to be used as the free local resonator was tuned to the proton Larmor frequency at 7T. Traveling wave MR experiments with and without the wireless free local resonator were performed on a living rat using a 7T whole body MR scanner. The signal-to-noise ratio (SNR) or sensitivity of the images acquired was compared and evaluated. In vivo 7T imaging results show that traveling wave MR with a wireless free local resonator placed near the head of a living rat achieves at least 10-fold SNR gain over the images acquired on the same rat using conventional traveling wave MR method, i.e. imaging with no free local resonators. The proposed free local resonator technique is able to enhance the MR sensitivity and acquisition efficiency of traveling wave MR at ultrahigh fields in vivo . This method can be a simple solution to alleviating low sensitivity problem of traveling wave MRI.

A simple and sensitive quantitation of N,N-dimethyltryptamine by gas chromatography with surface ionization detection.

PubMed

Ishii, A; Seno, H; Suzuki, O; Hattori, H; Kumazawa, T

1997-01-01

A simple and sensitive method for determination of N,N-dimethyltryptamine (DMT) by gas chromatography (GC) with surface ionization detection (SID) is presented. Whole blood or urine, containing DMT and gramine (internal standard), was subjected to solid-phase extraction with a Sep-Pak C18 cartridge before analysis by GC-SID. The calibration curve was linear in the DMT range of 1.25-20 ng/mL blood or urine. The detection limit of DMT was about 0.5 ng/mL (10 pg on-column). The recovery of both DMT and gramine spiked in biological fluids was above 86%.

A robust color signal processing with wide dynamic range WRGB CMOS image sensor

NASA Astrophysics Data System (ADS)

Kawada, Shun; Kuroda, Rihito; Sugawa, Shigetoshi

2011-01-01

We have developed a robust color reproduction methodology by a simple calculation with a new color matrix using the formerly developed wide dynamic range WRGB lateral overflow integration capacitor (LOFIC) CMOS image sensor. The image sensor was fabricated through a 0.18 μm CMOS technology and has a 45 degrees oblique pixel array, the 4.2 μm effective pixel pitch and the W pixels. A W pixel was formed by replacing one of the two G pixels in the Bayer RGB color filter. The W pixel has a high sensitivity through the visible light waveband. An emerald green and yellow (EGY) signal is generated from the difference between the W signal and the sum of RGB signals. This EGY signal mainly includes emerald green and yellow lights. These colors are difficult to be reproduced accurately by the conventional simple linear matrix because their wave lengths are in the valleys of the spectral sensitivity characteristics of the RGB pixels. A new linear matrix based on the EGY-RGB signal was developed. Using this simple matrix, a highly accurate color processing with a large margin to the sensitivity fluctuation and noise has been achieved.

On simple aerodynamic sensitivity derivatives for use in interdisciplinary optimization

NASA Technical Reports Server (NTRS)

Doggett, Robert V., Jr.

1991-01-01

Low-aspect-ratio and piston aerodynamic theories are reviewed as to their use in developing aerodynamic sensitivity derivatives for use in multidisciplinary optimization applications. The basic equations relating surface pressure (or lift and moment) to normal wash are given and discussed briefly for each theory. The general means for determining selected sensitivity derivatives are pointed out. In addition, some suggestions in very general terms are included as to sample problems for use in studying the process of using aerodynamic sensitivity derivatives in optimization studies.

Active rc filter permits easy trade-off of amplifier gain and sensitivity to gain

NASA Technical Reports Server (NTRS)

Kerwin, W. J.; Shaffer, C. V.

1968-01-01

Passive RC network was designed with zeros of transmission in the right half of the complex frequency plane in the feedback loop of a simple negative-gain amplifier. The proper positioning provides any desired trade-off between amplifier gain and sensitivity to amplifier gain.

Simplified methods of evaluating colonies for levels of Varroa Sensitive Hygiene (VSH)

USDA-ARS?s Scientific Manuscript database

Varroa sensitive hygiene (VSH) is a trait of honey bees, Apis mellifera, that supports resistance to varroa mites, Varroa destructor. Components of VSH were evaluated to identify simple methods for selection of the trait. Varroa mite population growth was measured in colonies with variable levels of...

Simple Method for Assaying Colistin Methanesulfonate in Plasma and Urine Using High-Performance Liquid Chromatography

PubMed Central

Li, Jian; Milne, Robert W.; Nation, Roger L.; Turnidge, John D.; Coulthard, Kingsley; Valentine, Jason

2002-01-01

A simple and sensitive high-performance liquid chromatographic method is described for the determination of colistimethate sodium in plasma and urine. The accuracy and reproducibility was within 10.1 and 11.2% with rat plasma and urine, respectively. Several commonly coadministered antibacterial agents do not interfere with the assay. PMID:12234867

Linear regression metamodeling as a tool to summarize and present simulation model results.

PubMed

Jalal, Hawre; Dowd, Bryan; Sainfort, François; Kuntz, Karen M

2013-10-01

Modelers lack a tool to systematically and clearly present complex model results, including those from sensitivity analyses. The objective was to propose linear regression metamodeling as a tool to increase transparency of decision analytic models and better communicate their results. We used a simplified cancer cure model to demonstrate our approach. The model computed the lifetime cost and benefit of 3 treatment options for cancer patients. We simulated 10,000 cohorts in a probabilistic sensitivity analysis (PSA) and regressed the model outcomes on the standardized input parameter values in a set of regression analyses. We used the regression coefficients to describe measures of sensitivity analyses, including threshold and parameter sensitivity analyses. We also compared the results of the PSA to deterministic full-factorial and one-factor-at-a-time designs. The regression intercept represented the estimated base-case outcome, and the other coefficients described the relative parameter uncertainty in the model. We defined simple relationships that compute the average and incremental net benefit of each intervention. Metamodeling produced outputs similar to traditional deterministic 1-way or 2-way sensitivity analyses but was more reliable since it used all parameter values. Linear regression metamodeling is a simple, yet powerful, tool that can assist modelers in communicating model characteristics and sensitivity analyses.

Rapid and sensitive detection of mink circovirus by recombinase polymerase amplification.

PubMed

Ge, Junwei; Shi, Yunjia; Cui, Xingyang; Gu, Shanshan; Zhao, Lili; Chen, Hongyan

2018-06-01

To date, the pathogenic role of mink circovirus (MiCV) remains unclear, and its prevalence and economic importance are unknown. Therefore, a rapid and sensitive molecular diagnosis is necessary for disease management and epidemiological surveillance. However, only PCR methods can identify MiCV infection at present. In this study, we developed a nested PCR and established a novel recombinase polymerase amplification (RPA) assay for MiCV detection. Sensitivity analysis showed that the detection limit of nested PCR and RPA assay was 10 1 copies/reaction, and these methods were more sensitive than conventional PCR, which has a detection limit of 10 5 copies/reaction. The RPA assay had no cross-reactivity with other related viral pathogens, and amplification was completed in less than 20 min with a simple device. Further assessment of clinical samples showed that the two assays were accurate in identifying positive and negative conventional PCR samples. The detection rate of MiCV by the RPA assay in clinical samples was 38.09%, which was 97% consistent with that by the nested PCR. The developed nested PCR is a highly sensitive tool for practical use, and the RPA assay is a simple, sensitive, and potential alternative method for rapid and accurate MiCV diagnosis. Copyright © 2018 Elsevier B.V. All rights reserved.

Curcumin restores diabetes induced neurochemical changes in the brain stem of Wistar rats.

PubMed

Kumar, Peeyush T; George, Naijil; Antony, Sherin; Paulose, Cheramadathikudiyil Skaria

2013-02-28

Diabetes mellitus, when poorly controlled, leads to debilitating central nervous system (CNS) complications including cognitive deficits, somatosensory and motor dysfunction. The present study investigated curcumin's potential in modulating diabetes induced neurochemical changes in brainstem. Expression analysis of cholinergic, insulin receptor and GLUT-3 in the brainstem of streptozotocin (STZ) induced diabetic rats were studied. Radioreceptor binding assays, gene expression studies and immunohistochemical analysis were done in the brainstem of male Wistar rats. Our result showed that Bmax of total muscarinic and muscarinic M3 receptors were increased and muscarinic M1 receptor was decreased in diabetic rats compared to control. mRNA level of muscarinic M3, α7-nicotinic acetylcholine, insulin receptors, acetylcholine esterase, choline acetyltransferase and GLUT-3 significantly increased and M1 receptor decreased in the brainstem of diabetic rats. Curcumin and insulin treatment restored the alterations and maintained all parameters to near control. The results show that diabetes is associated with significant reduction in brainstem function coupled with altered cholinergic, insulin receptor and GLUT-3 gene expression. The present study indicates beneficial effect of curcumin in diabetic rats by regulating the cholinergic, insulin receptor and GLUT-3 in the brainstem similar to the responses obtained with insulin therapy. Copyright © 2013 Elsevier B.V. All rights reserved.

Regulation of 5alpha-reductase isoforms by oxytocin in the rat ventral prostate.

PubMed

Assinder, S J; Johnson, C; King, K; Nicholson, H D

2004-12-01

Oxytocin (OT) is present in the male reproductive tract, where it is known to modulate contractility, cell growth, and steroidogenesis. Little is known about how OT regulates these processes. This study describes the localization of OT receptor in the rat ventral prostate and investigates if OT regulates gene expression and/or activity of 5alpha-reductase isoforms I and II. The ventral prostates of adult male Wistar rats were collected following daily sc administration of saline (control), OT, a specific OT antagonist or both OT plus antagonist for 3 d. Expression of the OT receptor was identified in the ventral prostate by RT-PCR and Western blot, and confirmed to be a single active binding site by radioreceptor assay. Immunohistochemistry localized the receptor to the epithelium of prostatic acini and to the stromal tissue. Real-time RT-PCR determined that OT treatment significantly reduced expression of 5alpha-reductase I but significantly increased 5alpha-reductase II expression in the ventral prostate. Activity of both isoforms of 5alpha-reductase was significantly increased by OT, resulting in increased concentration of prostatic dihydrotestosterone. In conclusion, OT is involved in regulating conversion of testosterone to the biologically active dihydrotestosterone in the rat ventral prostate. It does so by differential regulation of 5alpha-reductase isoforms I and II.

Restrictive vs. non-restrictive composition: a magnetoencephalography study

PubMed Central

Leffel, Timothy; Lauter, Miriam; Westerlund, Masha; Pylkkänen, Liina

2014-01-01

Recent research on the brain mechanisms underlying language processing has implicated the left anterior temporal lobe (LATL) as a central region for the composition of simple phrases. Because these studies typically present their critical stimuli without contextual information, the sensitivity of LATL responses to contextual factors is unknown. In this magnetoencephalography (MEG) study, we employed a simple question-answer paradigm to manipulate whether a prenominal adjective or determiner is interpreted restrictively, i.e., as limiting the set of entities under discussion. Our results show that the LATL is sensitive to restriction, with restrictive composition eliciting higher responses than non-restrictive composition. However, this effect was only observed when the restricting element was a determiner, adjectival stimuli showing the opposite pattern, which we hypothesise to be driven by the special pragmatic properties of non-restrictive adjectives. Overall, our results demonstrate a robust sensitivity of the LATL to high level contextual and potentially also pragmatic factors. PMID:25379512

Flexible, highly sensitive pressure sensor with a wide range based on graphene-silk network structure

NASA Astrophysics Data System (ADS)

Liu, Ying; Tao, Lu-Qi; Wang, Dan-Yang; Zhang, Tian-Yu; Yang, Yi; Ren, Tian-Ling

2017-03-01

In this paper, a flexible, simple-preparation, and low-cost graphene-silk pressure sensor based on soft silk substrate through thermal reduction was demonstrated. Taking silk as the support body, the device had formed a three-dimensional structure with ordered multi-layer structure. Through a simple and low-cost process technology, graphene-silk pressure sensor can achieve the sensitivity value of 0.4 kPa - 1 , and the measurement range can be as high as 140 kPa. Besides, pressure sensor can have a good combination with knitted clothing and textile product. The signal had good reproducibility in response to different pressures. Furthermore, graphene-silk pressure sensor can not only detect pressure higher than 100 kPa, but also can measure weak body signals. The characteristics of high-sensitivity, good repeatability, flexibility, and comfort for skin provide the high possibility to fit on various wearable electronics.

Enhanced sensitivity for optical loss measurement in planar thin-films (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yuan, Hua-Kang

2016-09-01

An organic-inorganic hybrid material benefits from processing advantages of organics and high refractive indices of inorganics. We focus on a titanium oxide hydrate system combined with common bulk polymers. In particular, we target thin-film structures of a few microns in thickness. Traditional Beer-Lambert approaches for measuring optical losses can only provide an upper limit estimate. This sensitivity is highly limited when considering the low-losses required for mid-range optical applications, on the order of 0.1 cm-1. For intensity based measurements, improving the sensitivity requires an increase in the optical path length. Instead, a new sensitive technique suitable for simple planar thin films is required. A number of systems were modelled to measure optical losses in films of 1 micron thick. The presented techniques utilise evanescent waves and total internal reflection to increase optical path length through the material. It was found that a new way of using prism coupling provides the greatest improvement in sensitivity. In keeping the requirements on the material simple, this method for measuring loss is well suited to any future developments of new materials in thin-film structures.

Analysis of the moments of the sensitivity function for resistivity over a homogeneous half-space: Rules of thumb for pseudoposition, offline sensitivity and resolution

NASA Astrophysics Data System (ADS)

Butler, S. L.

2017-08-01

It is instructive to consider the sensitivity function for a homogeneous half space for resistivity since it has a simple mathematical formula and it does not require a priori knowledge of the resistivity of the ground. Past analyses of this function have allowed visualization of the regions that contribute most to apparent resistivity measurements with given array configurations. The horizontally integrated form of this equation gives the sensitivity function for an infinitesimally thick horizontal slab with a small resistivity contrast and analysis of this function has admitted estimates of the depth of investigation for a given electrode array. Recently, it has been shown that the average of the vertical coordinate over this function yields a simple formula that can be used to estimate the depth of investigation. The sensitivity function for a vertical inline slab has also been previously calculated. In this contribution, I show that the sensitivity function for a homogeneous half-space can also be integrated so as to give sensitivity functions to semi-infinite vertical slabs that are perpendicular to the array axis. These horizontal sensitivity functions can, in turn, be integrated over the spatial coordinates to give the mean horizontal positions of the sensitivity functions. The mean horizontal positions give estimates for the centres of the regions that affect apparent resistivity measurements for arbitrary array configuration and can be used as horizontal positions when plotting pseudosections even for non-collinear arrays. The mean of the horizontal coordinate that is perpendicular to a collinear array also gives a simple formula for estimating the distance over which offline resistivity anomalies will have a significant effect. The root mean square (rms) widths of the sensitivity functions are also calculated in each of the coordinate directions as an estimate of the inverse of the resolution of a given array. For depth and in the direction perpendicular to the array, the rms thickness is shown to be very similar to the mean distance. For the direction parallel to the array, the rms thickness is shown to be proportional to the array length and similar to the array length divided by 2 for many arrays. I expect that these formulas will provide useful rules of thumb for estimating the centres and extents of regions influencing apparent resistivity measurements for survey planning and for education.

Limited predictive ability of surrogate indices of insulin sensitivity/resistance in Asian-Indian men.

PubMed

Muniyappa, Ranganath; Irving, Brian A; Unni, Uma S; Briggs, William M; Nair, K Sreekumaran; Quon, Michael J; Kurpad, Anura V

2010-12-01

Insulin resistance is highly prevalent in Asian Indians and contributes to worldwide public health problems, including diabetes and related disorders. Surrogate measurements of insulin sensitivity/resistance are used frequently to study Asian Indians, but these are not formally validated in this population. In this study, we compared the ability of simple surrogate indices to accurately predict insulin sensitivity as determined by the reference glucose clamp method. In this cross-sectional study of Asian-Indian men (n = 70), we used a calibration model to assess the ability of simple surrogate indices for insulin sensitivity [quantitative insulin sensitivity check index (QUICKI), homeostasis model assessment (HOMA2-IR), fasting insulin-to-glucose ratio (FIGR), and fasting insulin (FI)] to predict an insulin sensitivity index derived from the reference glucose clamp method (SI(Clamp)). Predictive accuracy was assessed by both root mean squared error (RMSE) of prediction as well as leave-one-out cross-validation-type RMSE of prediction (CVPE). QUICKI, FIGR, and FI, but not HOMA2-IR, had modest linear correlations with SI(Clamp) (QUICKI: r = 0.36; FIGR: r = -0.36; FI: r = -0.27; P < 0.05). No significant differences were noted among CVPE or RMSE from any of the surrogate indices when compared with QUICKI. Surrogate measurements of insulin sensitivity/resistance such as QUICKI, FIGR, and FI are easily obtainable in large clinical studies, but these may only be useful as secondary outcome measurements in assessing insulin sensitivity/resistance in clinical studies of Asian Indians.

Evidence supporting oral sensitivity to complex carbohydrates independent of sweet taste sensitivity in humans.

PubMed

Low, Julia Y Q; Lacy, Kathleen E; McBride, Robert L; Keast, Russell S J

2017-01-01

Compared to simple sugars, complex carbohydrates have been assumed invisible to taste. However, two recent studies proposed that there may be a perceivable taste quality elicited by complex carbohydrates independent of sweet taste. There is precedent with behavioural studies demonstrating that rats are very attracted to complex carbohydrates, and that complex carbohydrates are preferred to simple sugars at low concentrations. This suggests that rats may have independent taste sensors for simple sugars and complex carbohydrates. The aim of this paper is to investigate oral sensitivities of two different classes of complex carbohydrates (a soluble digestible and a soluble non-digestible complex carbohydrate), and to compare these to other caloric and non-nutritive sweeteners in addition to the prototypical tastes using two commonly used psychophysical measures. There were strong correlations between the detection thresholds and mean intensity ratings for complex carbohydrates (maltodextrin, oligofructose) (r = 0.94, P < 0.001). There were no significant correlations between the detection thresholds of the complex carbohydrates (maltodextrin, oligofructose) and the sweeteners (glucose, fructose, sucralose, Rebaudioside A, erythritol) (all P > 0.05). However, moderate correlations were observed between perceived intensities of complex carbohydrates and sweeteners (r = 0.48-0.61, P < 0.05). These data provide evidence that complex carbohydrates can be sensed in the oral cavity over a range of concentrations independent of sweet taste sensitivity at low concentrations, but with partial overlap with sweet taste intensity at higher concentrations.

Evidence supporting oral sensitivity to complex carbohydrates independent of sweet taste sensitivity in humans

PubMed Central

Lacy, Kathleen E.; Keast, Russell S. J.

2017-01-01

Compared to simple sugars, complex carbohydrates have been assumed invisible to taste. However, two recent studies proposed that there may be a perceivable taste quality elicited by complex carbohydrates independent of sweet taste. There is precedent with behavioural studies demonstrating that rats are very attracted to complex carbohydrates, and that complex carbohydrates are preferred to simple sugars at low concentrations. This suggests that rats may have independent taste sensors for simple sugars and complex carbohydrates. The aim of this paper is to investigate oral sensitivities of two different classes of complex carbohydrates (a soluble digestible and a soluble non-digestible complex carbohydrate), and to compare these to other caloric and non-nutritive sweeteners in addition to the prototypical tastes using two commonly used psychophysical measures. There were strong correlations between the detection thresholds and mean intensity ratings for complex carbohydrates (maltodextrin, oligofructose) (r = 0.94, P < 0.001). There were no significant correlations between the detection thresholds of the complex carbohydrates (maltodextrin, oligofructose) and the sweeteners (glucose, fructose, sucralose, Rebaudioside A, erythritol) (all P > 0.05). However, moderate correlations were observed between perceived intensities of complex carbohydrates and sweeteners (r = 0.48–0.61, P < 0.05). These data provide evidence that complex carbohydrates can be sensed in the oral cavity over a range of concentrations independent of sweet taste sensitivity at low concentrations, but with partial overlap with sweet taste intensity at higher concentrations. PMID:29281655

Validation of simple indexes to assess insulin sensitivity during pregnancy in Wistar and Sprague-Dawley rats.

PubMed

Cacho, J; Sevillano, J; de Castro, J; Herrera, E; Ramos, M P

2008-11-01

Insulin resistance plays a role in the pathogenesis of diabetes, including gestational diabetes. The glucose clamp is considered the gold standard for determining in vivo insulin sensitivity, both in human and in animal models. However, the clamp is laborious, time consuming and, in animals, requires anesthesia and collection of multiple blood samples. In human studies, a number of simple indexes, derived from fasting glucose and insulin levels, have been obtained and validated against the glucose clamp. However, these indexes have not been validated in rats and their accuracy in predicting altered insulin sensitivity remains to be established. In the present study, we have evaluated whether indirect estimates based on fasting glucose and insulin levels are valid predictors of insulin sensitivity in nonpregnant and 20-day-pregnant Wistar and Sprague-Dawley rats. We have analyzed the homeostasis model assessment of insulin resistance (HOMA-IR), the quantitative insulin sensitivity check index (QUICKI), and the fasting glucose-to-insulin ratio (FGIR) by comparing them with the insulin sensitivity (SI(Clamp)) values obtained during the hyperinsulinemic-isoglycemic clamp. We have performed a calibration analysis to evaluate the ability of these indexes to accurately predict insulin sensitivity as determined by the reference glucose clamp. Finally, to assess the reliability of these indexes for the identification of animals with impaired insulin sensitivity, performance of the indexes was analyzed by receiver operating characteristic (ROC) curves in Wistar and Sprague-Dawley rats. We found that HOMA-IR, QUICKI, and FGIR correlated significantly with SI(Clamp), exhibited good sensitivity and specificity, accurately predicted SI(Clamp), and yielded lower insulin sensitivity in pregnant than in nonpregnant rats. Together, our data demonstrate that these indexes provide an easy and accurate measure of insulin sensitivity during pregnancy in the rat.

STUDIES ON THE SENSITIZATION OF ANIMALS WITH SIMPLE CHEMICAL COMPOUNDS

PubMed Central

Landsteiner, K.; Di Somma, A. A.

1940-01-01

Sensitization of guinea pigs to picric acid was obtained by application of oil solutions to the skin, preferably on inflamed sites or by treatment with a compound of picric acid with n-butyl-p-aminobenzoate. The lesions obtained in sensitive animals on superficial administration bore resemblance to human eczema. It seems probable that picric acid sensitization is an instance where a substance does not sensitize directly but after conversion into a more reactive compound, a principle which should be of wider application to instances where the original substance does not readily form conjugates. PMID:19871030

Sensitivity of Lumped Constraints Using the Adjoint Method

NASA Technical Reports Server (NTRS)

Akgun, Mehmet A.; Haftka, Raphael T.; Wu, K. Chauncey; Walsh, Joanne L.

1999-01-01

Adjoint sensitivity calculation of stress, buckling and displacement constraints may be much less expensive than direct sensitivity calculation when the number of load cases is large. Adjoint stress and displacement sensitivities are available in the literature. Expressions for local buckling sensitivity of isotropic plate elements are derived in this study. Computational efficiency of the adjoint method is sensitive to the number of constraints and, therefore, the method benefits from constraint lumping. A continuum version of the Kreisselmeier-Steinhauser (KS) function is chosen to lump constraints. The adjoint and direct methods are compared for three examples: a truss structure, a simple HSCT wing model, and a large HSCT model. These sensitivity derivatives are then used in optimization.

Survey Definitions of Gout for Epidemiologic Studies: Comparison With Crystal Identification as the Gold Standard.

PubMed

Dalbeth, Nicola; Schumacher, H Ralph; Fransen, Jaap; Neogi, Tuhina; Jansen, Tim L; Brown, Melanie; Louthrenoo, Worawit; Vazquez-Mellado, Janitzia; Eliseev, Maxim; McCarthy, Geraldine; Stamp, Lisa K; Perez-Ruiz, Fernando; Sivera, Francisca; Ea, Hang-Korng; Gerritsen, Martijn; Scire, Carlo A; Cavagna, Lorenzo; Lin, Chingtsai; Chou, Yin-Yi; Tausche, Anne-Kathrin; da Rocha Castelar-Pinheiro, Geraldo; Janssen, Matthijs; Chen, Jiunn-Horng; Cimmino, Marco A; Uhlig, Till; Taylor, William J

2016-12-01

To identify the best-performing survey definition of gout from items commonly available in epidemiologic studies. Survey definitions of gout were identified from 34 epidemiologic studies contributing to the Global Urate Genetics Consortium (GUGC) genome-wide association study. Data from the Study for Updated Gout Classification Criteria (SUGAR) were randomly divided into development and test data sets. A data-driven case definition was formed using logistic regression in the development data set. This definition, along with definitions used in GUGC studies and the 2015 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) gout classification criteria were applied to the test data set, using monosodium urate crystal identification as the gold standard. For all tested GUGC definitions, the simple definition of "self-report of gout or urate-lowering therapy use" had the best test performance characteristics (sensitivity 82%, specificity 72%). The simple definition had similar performance to a SUGAR data-driven case definition with 5 weighted items: self-report, self-report of doctor diagnosis, colchicine use, urate-lowering therapy use, and hyperuricemia (sensitivity 87%, specificity 70%). Both of these definitions performed better than the 1977 American Rheumatism Association survey criteria (sensitivity 82%, specificity 67%). Of all tested definitions, the 2015 ACR/EULAR criteria had the best performance (sensitivity 92%, specificity 89%). A simple definition of "self-report of gout or urate-lowering therapy use" has the best test performance characteristics of existing definitions that use routinely available data. A more complex combination of features is more sensitive, but still lacks good specificity. If a more accurate case definition is required for a particular study, the 2015 ACR/EULAR gout classification criteria should be considered. © 2016, American College of Rheumatology.

Simple Nutrition Screening Tool for Pediatric Inpatients.

PubMed

White, Melinda; Lawson, Karen; Ramsey, Rebecca; Dennis, Nicole; Hutchinson, Zoe; Soh, Xin Ying; Matsuyama, Misa; Doolan, Annabel; Todd, Alwyn; Elliott, Aoife; Bell, Kristie; Littlewood, Robyn

2016-03-01

Pediatric nutrition risk screening tools are not routinely implemented throughout many hospitals, despite prevalence studies demonstrating malnutrition is common in hospitalized children. Existing tools lack the simplicity of those used to assess nutrition risk in the adult population. This study reports the accuracy of a new, quick, and simple pediatric nutrition screening tool (PNST) designed to be used for pediatric inpatients. The pediatric Subjective Global Nutrition Assessment (SGNA) and anthropometric measures were used to develop and assess the validity of 4 simple nutrition screening questions comprising the PNST. Participants were pediatric inpatients in 2 tertiary pediatric hospitals and 1 regional hospital. Two affirmative answers to the PNST questions were found to maximize the specificity and sensitivity to the pediatric SGNA and body mass index (BMI) z scores for malnutrition in 295 patients. The PNST identified 37.6% of patients as being at nutrition risk, whereas the pediatric SGNA identified 34.2%. The sensitivity and specificity of the PNST compared with the pediatric SGNA were 77.8% and 82.1%, respectively. The sensitivity of the PNST at detecting patients with a BMI z score of less than -2 was 89.3%, and the specificity was 66.2%. Both the PNST and pediatric SGNA were relatively poor at detecting patients who were stunted or overweight, with the sensitivity and specificity being less than 69%. The PNST provides a sensitive, valid, and simpler alternative to existing pediatric nutrition screening tools such as Screening Tool for the Assessment of Malnutrition in Pediatrics (STAMP), Screening Tool Risk on Nutritional status and Growth (STRONGkids), and Paediatric Yorkhill Malnutrition Score (PYMS) to ensure the early detection of hospitalized children at nutrition risk. © 2014 American Society for Parenteral and Enteral Nutrition.

Sensitivity and Specificity of an Operon Immunochromatographic Test in Serum and Whole-Blood Samples for the Diagnosis of Trypanosoma cruzi Infection in Spain, an Area of Nonendemicity

PubMed Central

Flores-Chavez, María; Cruz, Israel; Nieto, Javier; Gárate, Teresa; Navarro, Miriam; Pérez-Ayala, Ana; López-Vélez, Rogelio

2012-01-01

Trypanosoma cruzi infection is an imported parasitic disease in Spain, and the majority of infected individuals are in the chronic phase of the disease. This study evaluated the sensitivity and specificity of the Operon immunochromatographic test (ICT-Operon; Simple Stick Chagas and Simple Chagas WB [whole blood]; Operon S.A., Spain) for different biological samples. Well-characterized serum samples were obtained from chagasic patients (n = 63), nonchagasic individuals (n = 95), visceral leishmaniasis patients (n = 38), and malaria patients (n = 55). Noncharacterized specimens were obtained from Latin American immigrants and individuals at risk with a clinical and/or epidemiological background: these specimens were recovered serum or plasma samples (n = 450), whole peripheral blood (n = 94), and capillary blood (n = 282). The concordance of the results by enzyme-linked immunosorbent assay and indirect immunofluorescence test was considered to be the “gold standard” for diagnosis. Serum and plasma samples were analyzed by Stick Chagas, and whole blood was analyzed by Simple Chagas WB. The sensitivity and specificity of the ICT-Operon in well-characterized samples were 100% and 97.9%, respectively. No cross-reactivity was found with samples obtained from visceral leishmaniasis patients. In contrast, a false-positive result was obtained in 27.3% of samples from malaria patients. The sensitivities of the rapid test in noncharacterized serum or plasma, peripheral blood, and capillary blood samples were 100%, 92.1%, and 86.4%, respectively, while the specificities were 91.6%, 93.6%, and 95% in each case. ICT-Operon showed variable sensitivity, depending on the kind of sample, performing better when serum or plasma samples were used. It could therefore be used for serological screening combined with any other conventional test. PMID:22761296

Simple and rapid method for the detection of Filobasidiella neoformans in a probiotic dairy product by using loop-mediated isothermal amplification.

PubMed

Ishikawa, Hiroshi; Kasahara, Kohei; Sato, Sumie; Shimakawa, Yasuhisa; Watanabe, Koichi

2014-05-16

Yeast contamination is a serious problem in the food industry and a major cause of food spoilage. Several yeasts, such as Filobasidiella neoformans, which cause cryptococcosis in humans, are also opportunistic pathogens, so a simple and rapid method for monitoring yeast contamination in food is essential. Here, we developed a simple and rapid method that utilizes loop-mediated isothermal amplification (LAMP) for the detection of F. neoformans. A set of five specific LAMP primers was designed that targeted the 5.8S-26S rDNA internal transcribed spacer 2 region of F. neoformans, and the primer set's specificity was confirmed. In a pure culture of F. neoformans, the LAMP assay had a lower sensitivity threshold of 10(2)cells/mL at a runtime of 60min. In a probiotic dairy product artificially contaminated with F. neoformans, the LAMP assay also had a lower sensitivity threshold of 10(2)cells/mL, which was comparable to the sensitivity of a quantitative PCR (qPCR) assay. We also developed a simple two-step method for the extraction of DNA from a probiotic dairy product that can be performed within 15min. This method involves initial protease treatment of the test sample at 45°C for 3min followed by boiling at 100°C for 5min under alkaline conditions. In a probiotic dairy product artificially contaminated with F. neoformans, analysis by means of our novel DNA extraction method followed by LAMP with our specific primer set had a lower sensitivity threshold of 10(3)cells/mL at a runtime of 60min. In contrast, use of our novel method of DNA extraction followed by qPCR assay had a lower sensitivity threshold of only 10(5)cells/mL at a runtime of 3 to 4h. Therefore, unlike the PCR assay, our LAMP assay can be used to quickly evaluate yeast contamination and is sensitive even for crude samples containing bacteria or background impurities. Our study provides a powerful tool for the primary screening of large numbers of food samples for yeast contamination. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessing Instructional Sensitivity Using the Pre-Post Difference Index: A Nontechnical Tool for Extension Educators

ERIC Educational Resources Information Center

Adedokun, Omolola A.

2018-01-01

This article provides an illustrative description of the pre-post difference index (PPDI), a simple, nontechnical yet robust tool for examining the instructional sensitivity of assessment items. Extension educators often design pretest-posttest instruments to assess the impact of their curricula on participants' knowledge and understanding of the…

A Role for Chunk Formation in Statistical Learning of Second Language Syntax

ERIC Educational Resources Information Center

Hamrick, Phillip

2014-01-01

Humans are remarkably sensitive to the statistical structure of language. However, different mechanisms have been proposed to account for such statistical sensitivities. The present study compared adult learning of syntax and the ability of two models of statistical learning to simulate human performance: Simple Recurrent Networks, which learn by…

Sensitivity calculations for iteratively solved problems

NASA Technical Reports Server (NTRS)

Haftka, R. T.

1985-01-01

The calculation of sensitivity derivatives of solutions of iteratively solved systems of algebraic equations is investigated. A modified finite difference procedure is presented which improves the accuracy of the calculated derivatives. The procedure is demonstrated for a simple algebraic example as well as an element-by-element preconditioned conjugate gradient iterative solution technique applied to truss examples.

Aptamer-aided target capturing with biocatalytic metal deposition: an electrochemical platform for sensitive detection of cancer cells.

PubMed

Yi, Zi; Li, Xiao-Yan; Gao, Qing; Tang, Li-Juan; Chu, Xia

2013-04-07

A novel aptamer biosensor for cancer cell assay has been reported on the basis of ultrasensitive electrochemical detection. Cancer cell capturing is first accomplished via aptamer-aided recognition, and the cell-aptamer binding events then mediate an alkaline phosphatase-catalyzed silver deposition reaction which can be probed by electrochemical detection. Following biocatalytic silver deposition, an efficient amplification approach for sensitive electrochemical measurements is demonstrated, for cell detection with high sensitivity. Ramos cell are used as a model case, a typical biomarker of the acute blood cell cancer, Burkitt's lymphoma. The results reveal that the developed technique displays desirable selectivity in Ramos cell discrimination, and linear response range from 10 to 10(6) cells with a detection limit as low as 10 cells. Due to the simple procedures, label-free and electrochemistry based detection format, this technique is simple and cost-effective, and exhibits excellent compatibility with miniaturization technologies. The electrochemical cell detection strategy may create an intrinsically specific and sensitive platform for cancer cell assay and associated studies.

The Sensitivity of Coded Mask Telescopes

NASA Technical Reports Server (NTRS)

Skinner, Gerald K.

2008-01-01

Simple formulae are often used to estimate the sensitivity of coded mask X-ray or gamma-ray telescopes, but t,hese are strictly only applicable if a number of basic assumptions are met. Complications arise, for example, if a grid structure is used to support the mask elements, if the detector spatial resolution is not good enough to completely resolve all the detail in the shadow of the mask or if any of a number of other simplifying conditions are not fulfilled. We derive more general expressions for the Poisson-noise-limited sensitivity of astronomical telescopes using the coded mask technique, noting explicitly in what circumstances they are applicable. The emphasis is on using nomenclature and techniques that result in simple and revealing results. Where no convenient expression is available a procedure is given which allows the calculation of the sensitivity. We consider certain aspects of the optimisation of the design of a coded mask telescope and show that when the detector spatial resolution and the mask to detector separation are fixed, the best source location accuracy is obtained when the mask elements are equal in size to the detector pixels.

Co-evolution of cooperation and cognition: the impact of imperfect deliberation and context-sensitive intuition

PubMed Central

Kagan, Ari; Rand, David G.

2017-01-01

How does cognitive sophistication impact cooperation? We explore this question using a model of the co-evolution of cooperation and cognition. In our model, agents confront social dilemmas and coordination games, and make decisions using intuition or deliberation. Intuition is automatic and effortless, but relatively (although not necessarily completely) insensitive to context. Deliberation, conversely, is costly but relatively (although not necessarily perfectly) sensitive to context. We find that regardless of the sensitivity of intuition and imperfection of deliberation, deliberating undermines cooperation in social dilemmas, whereas deliberating can increase cooperation in coordination games if intuition is sufficiently sensitive. Furthermore, when coordination games are sufficiently likely, selection favours a strategy whose intuitive response ignores the contextual cues available and cooperates across contexts. Thus, we see how simple cognition can arise from active selection for simplicity, rather than just be forced to be simple due to cognitive constraints. Finally, we find that when deliberation is imperfect, the favoured strategy increases cooperation in social dilemmas (as a result of reducing deliberation) as the benefit of cooperation to the recipient increases. PMID:28330915

Sampling and position effects in the Electronically Steered Thinned Array Radiometer (ESTAR)

NASA Technical Reports Server (NTRS)

Katzberg, Stephen J.

1993-01-01

A simple engineering level model of the Electronically Steered Thinned Array Radiometer (ESTAR) is developed that allows an identification of the major effects of the sampling process involved with this technique. It is shown that the ESTAR approach is sensitive to aliasing and has a highly non-uniform sensitivity profile. It is further shown that the ESTAR approach is strongly sensitive to position displacements of the low-density sampling antenna elements.

Evaluation of a simple phenotypic method for the detection of carbapenemase-producing Enterobacteriaceae.

PubMed

Saito, Ryoichi; Koyano, Saho; Dorin, Misato; Higurashi, Yoshimi; Misawa, Yoshiki; Nagano, Noriyuki; Kaneko, Takamasa; Moriya, Kyoji

2015-01-01

We investigated the performance of a phenotypic test, the Carbapenemase Detection Set (MAST-CDS), for the identification of carbapenemase-producing Enterobacteriaceae. Our results indicated that MAST-CDS is rapid, easily performed, simple to interpret, and highly sensitive for the identification of carbapenemase producers, particularly imipenemase producers. Copyright © 2014 Elsevier B.V. All rights reserved.

Simple immunoglobulin G sensor based on thin core single-mode fiber

NASA Astrophysics Data System (ADS)

Zheng, Yingfang; Lang, Tingting; Shen, Tingting; Shen, Changyu

2018-03-01

In this paper, a simple fiber biosensor (FOB) for immunoglobulin G (IgG) detection is designed and experimentally verified. The FOB is constructed by a 20 mm long thin core single-mode fiber (TCSMF) sandwiched between two single-mode optical fibers (SMFs). First, the refractive index (RI) sensitivity of the fiber structures is calculated by the beam propagation method. The refractive index sensing experiment is performed using different concentrations of glycerol solutions, and the experimental results are mostly consistent with the simulation predictions. The experimental RI sensitivity increases with the surrounding RI and reaches 82.7 nm/RIU. Then the surface of the FOB is functionalized by APTES for covalent bonding. The human IgG and goat anti-human IgG are chosen as a bioconjugated pair to examine the bio-sensing effectiveness of this FOB. The sensitivity of IgG detection is determined to be 10.4 nm/(mg/ml). And the serum IgG concentration in normal adults lies within the range of 6-16 mg/ml (Worsfold et al., 1985), so the sensor is applicable to human IgG monitoring. The specificity of the FOB is also verified by a contrast experiment conducted using rabbit immunoglobulin G. The proposed FOB is simple, low loss, cost-effective, and can be used for various biological and chemical applications.

Development and Application of a Sensitive, Second Antibody Format Enzymeimmunoassay (EIA) for Estimation of Plasma FSH in Mithun (Bos frontalis).

PubMed

Mondal, Mohan; Baruah, Kishore Kumar; Prakash, B S

2016-01-01

Mithun (Bos frontalis) is a semi-wild rare ruminant species. A simple sensitive enzymeimmunoassay suitable for assaying FSH in the blood plasma of mithun is not available which thereby limits our ability to understand this species reproductive processes. Therefore, the aim of this article was to develop a simple and sensitive enzymeimmunoassay (EIA) for estimation of FSH in mithun plasma and apply the assay to understand the estrous cycle and superovulatory process in this species. To accomplish this goal, biotinylated FSH was bridged between streptavidin-peroxidase and immobilized antiserum in a competitive assay. Forty microlitre mithun plasma was used directly in the EIA. The FSH standards were prepared in hormone free plasma and ranged from 5-1280 pg/well/40 μL. The sensitivity of EIA was 5 pg/well FSH, which corresponds to 0.125 ng/mL plasma and the 50% relative binding sensitivity was 90 pg/well/40 μL. Although the shape of the standard curve was not influenced by different plasma volumes viz. 40 and 80 μL, a slight drop in the OD450 was observed with the increasing volume of plasma. Parallelism tests conducted between the endogenous mithun FSH and bovine FSH standards showed good homology between them. Plasma FSH estimated using the developed EIA and commercially available FSH EIA kit in the same samples were correlated (r = 0.98) and showed linearity. Both the Intra- and inter-assay CV were below 6%. Recovery of known concentrations of added FSH showed linearity (r = 0.99). The developed EIA was further validated biologically by estimating FSH in cyclic cows for the entire estrous cycle, in mithun heifers administered with GnRH analogues and in mithun cows during superovulatory treatment with FSH. In conclusion, the EIA developed for FSH determination in mithun blood plasma is simple and highly sensitive for estimation of mithun FSH in all physiological conditions.

Rapid, Fully Automated Digital Immunoassay for p24 Protein with the Sensitivity of Nucleic Acid Amplification for Detecting Acute HIV Infection.

PubMed

Cabrera, Carlos; Chang, Lei; Stone, Mars; Busch, Michael; Wilson, David H

2015-11-01

Nucleic acid testing (NAT) has become the standard for high sensitivity in detecting low levels of virus. However, adoption of NAT can be cost prohibitive in low-resource settings where access to extreme sensitivity could be clinically advantageous for early detection of infection. We report development and preliminary validation of a simple, low-cost, fully automated digital p24 antigen immunoassay with the sensitivity of quantitative NAT viral load (NAT-VL) methods for detection of acute HIV infection. We developed an investigational 69-min immunoassay for p24 capsid protein for use on a novel digital analyzer on the basis of single-molecule-array technology. We evaluated the assay for sensitivity by dilution of standardized preparations of p24, cultured HIV, and preseroconversion samples. We characterized analytical performance and concordance with 2 NAT-VL methods and 2 contemporary p24 Ag/Ab combination immunoassays with dilutions of viral isolates and samples from the earliest stages of HIV infection. Analytical sensitivity was 0.0025 ng/L p24, equivalent to 60 HIV RNA copies/mL. The limit of quantification was 0.0076 ng/L, and imprecision across 10 runs was <10% for samples as low as 0.09 ng/L. Clinical specificity was 95.1%. Sensitivity concordance vs NAT-VL on dilutions of preseroconversion samples and Group M viral isolates was 100%. The digital immunoassay exhibited >4000-fold greater sensitivity than contemporary immunoassays for p24 and sensitivity equivalent to that of NAT methods for early detection of HIV. The data indicate that NAT-level sensitivity for acute HIV infection is possible with a simple, low-cost digital immunoassay. © 2015 American Association for Clinical Chemistry.

A rapid and ultrasensitive SERRS assay for histidine and tyrosine based on azo coupling.

PubMed

Sui, Huimin; Wang, Yue; Yu, Zhi; Cong, Qian; Han, Xiao Xia; Zhao, Bing

2016-10-01

A simple and highly sensitive surface-enhanced resonance Raman scattering (SERRS)-based approach coupled with azo coupling reaction has been put forward for quantitative analysis of histidine and tyrosine. The SERRS-based assay is simple and rapid by mixing the azo reaction products with silver nanoparticles (AgNPs) for measurements within 2min. The limits of detection (LODs) of the method are as low as 4.33×10(-11) and 8.80×10(-11)M for histidine and tyrosine, respectively. Moreover, the SERRS fingerprint information specific to corresponding amino acids guarantees the selective detection for the target histidine and tyrosine. The results from serum indicated the potential application of the proposed approach into biological samples. Compared with the methods ever reported, the main advantages of this methodology are simpleness, rapidity without time-consuming separation or pretreatment steps, high sensitivity, selectivity and the potential for determination of other molecules containing imidazole or phenol groups. Copyright © 2016 Elsevier B.V. All rights reserved.

On the possibility (or lack thereof) of agreement between experiment and computation of flows over wings at moderate Reynolds number.

PubMed

Tank, J; Smith, L; Spedding, G R

2017-02-06

The flight of many birds and bats, and their robotic counterparts, occurs over a range of chord-based Reynolds numbers from 1 × 10 4 to 1.5 × 10 5 . It is precisely over this range where the aerodynamics of simple, rigid, fixed wings becomes extraordinarily sensitive to small changes in geometry and the environment, with two sets of consequences. The first is that practical lifting devices at this scale will likely not be simple, rigid, fixed wings. The second is that it becomes non-trivial to make baseline comparisons for experiment and computation, when either one can be wrong. Here we examine one ostensibly simple case of the NACA 0012 aerofoil and make careful comparison between the technical literature, and new experiments and computations. The agreement (or lack thereof) will establish one or more baseline results and some sensitivities around them. The idea is that the diagnostic procedures will help to guide comparisons and predictions in subsequent more complex cases.

On the possibility (or lack thereof) of agreement between experiment and computation of flows over wings at moderate Reynolds number

PubMed Central

Tank, J.; Smith, L.

2017-01-01

The flight of many birds and bats, and their robotic counterparts, occurs over a range of chord-based Reynolds numbers from 1 × 104 to 1.5 × 105. It is precisely over this range where the aerodynamics of simple, rigid, fixed wings becomes extraordinarily sensitive to small changes in geometry and the environment, with two sets of consequences. The first is that practical lifting devices at this scale will likely not be simple, rigid, fixed wings. The second is that it becomes non-trivial to make baseline comparisons for experiment and computation, when either one can be wrong. Here we examine one ostensibly simple case of the NACA 0012 aerofoil and make careful comparison between the technical literature, and new experiments and computations. The agreement (or lack thereof) will establish one or more baseline results and some sensitivities around them. The idea is that the diagnostic procedures will help to guide comparisons and predictions in subsequent more complex cases. PMID:28163869

A simple reduction-sensitive micelles co-delivery of paclitaxel and dasatinib to overcome tumor multidrug resistance

PubMed Central

Lu, Xiao; He, Jing; Jin, Shidai

2017-01-01

Multidrug resistance (MDR) is one of the major obstacles in successful chemotherapy. The combination of chemotherapy drugs and multidrug-resistant reversing agents for treating MDR tumor is a good strategy to overcome MDR. In this work, we prepared the simple redox-responsive micelles based on mPEG-SS-C18 as a co-delivery system to load the paclitaxel (PTX) and dasatinib (DAS) for treatment of MCF-7/ADR cells. The co-loaded micelles had a good dispersity and a spherical shape with a uniform size distribution, and they could quickly disassemble and rapidly release drugs under the reduction environment. Compared with MCF-7 cells, the DAS and PTX co-loaded redox-sensitive micelle (SS-PDNPs) showed stronger cytotoxicity and a more improving intracellular drug concentration than other drug formulations in MCF-7/ADR cells. In summary, the results suggested that the simple co-delivery micelles of PTX and DAS possessed significant potential to overcome drug resistance in cancer therapy. PMID:29138561

Real versus Artificial Variation in the Thermal Sensitivity of Biological Traits.

PubMed

Pawar, Samraat; Dell, Anthony I; Savage, Van M; Knies, Jennifer L

2016-02-01

Whether the thermal sensitivity of an organism's traits follows the simple Boltzmann-Arrhenius model remains a contentious issue that centers around consideration of its operational temperature range and whether the sensitivity corresponds to one or a few underlying rate-limiting enzymes. Resolving this issue is crucial, because mechanistic models for temperature dependence of traits are required to predict the biological effects of climate change. Here, by combining theory with data on 1,085 thermal responses from a wide range of traits and organisms, we show that substantial variation in thermal sensitivity (activation energy) estimates can arise simply because of variation in the range of measured temperatures. Furthermore, when thermal responses deviate systematically from the Boltzmann-Arrhenius model, variation in measured temperature ranges across studies can bias estimated activation energy distributions toward higher mean, median, variance, and skewness. Remarkably, this bias alone can yield activation energies that encompass the range expected from biochemical reactions (from ~0.2 to 1.2 eV), making it difficult to establish whether a single activation energy appropriately captures thermal sensitivity. We provide guidelines and a simple equation for partially correcting for such artifacts. Our results have important implications for understanding the mechanistic basis of thermal responses of biological traits and for accurately modeling effects of variation in thermal sensitivity on responses of individuals, populations, and ecological communities to changing climatic temperatures.

Enhanced Sensitivity to Detection Nanomolar Level of Cu2 + Compared to Spectrophotometry Method by Functionalized Gold Nanoparticles: Design of Sensor Assisted by Exploiting First-order Data with Chemometrics

NASA Astrophysics Data System (ADS)

Rasouli, Zolaikha; Ghavami, Raouf

2018-02-01

A simple, sensitive and efficient colorimetric assay platform for the determination of Cu2 + was proposed with the aim of developing sensitive detection based on the aggregation of AuNPs in presence of a histamine H2-receptor antagonist (famotidine, FAM) as recognition site. This study is the first to demonstrate that the molar extinction coefficients of the complexes formed by FAM and Cu2 + are very low (by analyzing the chemometrics methods on the first order data arising from different metal to ligand ratio method), leading to the undesirable sensitivity of FAM-based assays. To resolve the problem of low sensitivity, the colorimetry method based on the Cu2 +-induced aggregation of AuNPs functionalized with FAM was introduced. This procedure is accompanied by a color change from bright red to blue which can be observed with the naked eyes. Detection sensitivity obtained by the developed method increased about 100 fold compared with the spectrophotometry method. This sensor exhibited a good linear relation between the absorbance ratios at 670 to 520 nm (A670/520) and the concentration in the range 2-110 nM with LOD = 0.76 nM. The satisfactory analytical performance of the proposed sensor facilitates the development of simple and affordable UV-Vis chemosensors for environmental applications.

Simple, Fast, and Sensitive Method for Quantification of Tellurite in Culture Media▿

PubMed Central

Molina, Roberto C.; Burra, Radhika; Pérez-Donoso, José M.; Elías, Alex O.; Muñoz, Claudia; Montes, Rebecca A.; Chasteen, Thomas G.; Vásquez, Claudio C.

2010-01-01

A fast, simple, and reliable chemical method for tellurite quantification is described. The procedure is based on the NaBH4-mediated reduction of TeO32− followed by the spectrophotometric determination of elemental tellurium in solution. The method is highly reproducible, is stable at different pH values, and exhibits linearity over a broad range of tellurite concentrations. PMID:20525868

Comparison between Surrogate Indexes of Insulin Sensitivity/Resistance and Hyperinsulinemic Euglycemic Glucose Clamps in Rhesus Monkeys

PubMed Central

Lee, Ho-Won; Muniyappa, Ranganath; Yan, Xu; Yue, Lilly Q.; Linden, Ellen H.; Chen, Hui; Hansen, Barbara C.

2011-01-01

The euglycemic glucose clamp is the reference method for assessing insulin sensitivity in humans and animals. However, clamps are ill-suited for large studies because of extensive requirements for cost, time, labor, and technical expertise. Simple surrogate indexes of insulin sensitivity/resistance including quantitative insulin-sensitivity check index (QUICKI) and homeostasis model assessment (HOMA) have been developed and validated in humans. However, validation studies of QUICKI and HOMA in both rats and mice suggest that differences in metabolic physiology between rodents and humans limit their value in rodents. Rhesus monkeys are a species more similar to humans than rodents. Therefore, in the present study, we evaluated data from 199 glucose clamp studies obtained from a large cohort of 86 monkeys with a broad range of insulin sensitivity. Data were used to evaluate simple surrogate indexes of insulin sensitivity/resistance (QUICKI, HOMA, Log HOMA, 1/HOMA, and 1/Fasting insulin) with respect to linear regression, predictive accuracy using a calibration model, and diagnostic performance using receiver operating characteristic. Most surrogates had modest linear correlations with SIClamp (r ≈ 0.4–0.64) with comparable correlation coefficients. Predictive accuracy determined by calibration model analysis demonstrated better predictive accuracy of QUICKI than HOMA and Log HOMA. Receiver operating characteristic analysis showed equivalent sensitivity and specificity of most surrogate indexes to detect insulin resistance. Thus, unlike in rodents but similar to humans, surrogate indexes of insulin sensitivity/resistance including QUICKI and log HOMA may be reasonable to use in large studies of rhesus monkeys where it may be impractical to conduct glucose clamp studies. PMID:21209021

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

NASA Astrophysics Data System (ADS)

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

2016-06-01

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

A sensitivity analysis method for the body segment inertial parameters based on ground reaction and joint moment regressor matrices.

PubMed

Futamure, Sumire; Bonnet, Vincent; Dumas, Raphael; Venture, Gentiane

2017-11-07

This paper presents a method allowing a simple and efficient sensitivity analysis of dynamics parameters of complex whole-body human model. The proposed method is based on the ground reaction and joint moment regressor matrices, developed initially in robotics system identification theory, and involved in the equations of motion of the human body. The regressor matrices are linear relatively to the segment inertial parameters allowing us to use simple sensitivity analysis methods. The sensitivity analysis method was applied over gait dynamics and kinematics data of nine subjects and with a 15 segments 3D model of the locomotor apparatus. According to the proposed sensitivity indices, 76 segments inertial parameters out the 150 of the mechanical model were considered as not influent for gait. The main findings were that the segment masses were influent and that, at the exception of the trunk, moment of inertia were not influent for the computation of the ground reaction forces and moments and the joint moments. The same method also shows numerically that at least 90% of the lower-limb joint moments during the stance phase can be estimated only from a force-plate and kinematics data without knowing any of the segment inertial parameters. Copyright © 2017 Elsevier Ltd. All rights reserved.

An improved method for detecting circulating microRNAs with S-Poly(T) Plus real-time PCR

PubMed Central

Niu, Yanqin; Zhang, Limin; Qiu, Huiling; Wu, Yike; Wang, Zhiwei; Zai, Yujia; Liu, Lin; Qu, Junle; Kang, Kang; Gou, Deming

2015-01-01

We herein describe a simple, sensitive and specific method for analysis of circulating microRNAs (miRNA), termed S-Poly(T) Plus real-time PCR assay. This new method is based on our previously developed S-Poly(T) method, in which a unique S-Poly(T) primer is used during reverse-transcription to increase sensitivity and specificity. Further increased sensitivity and simplicity of S-Poly(T) Plus, in comparison with the S-Poly(T) method, were achieved by a single-step, multiple-stage reaction, where RNAs were polyadenylated and reverse-transcribed at the same time. The sensitivity of circulating miRNA detection was further improved by a modified method of total RNA isolation from serum/plasma, S/P miRsol, in which glycogen was used to increase the RNA yield. We validated our methods by quantifying miRNA expression profiles in the sera of the patients with pulmonary arterial hypertension associated with congenital heart disease. In conclusion, we developed a simple, sensitive, and specific method for detecting circulating miRNAs that allows the measurement of 266 miRNAs from 100 μl of serum or plasma. This method presents a promising tool for basic miRNA research and clinical diagnosis of human diseases based on miRNA biomarkers. PMID:26459910

Highly sensitive and specific colorimetric detection of cancer cells via dual-aptamer target binding strategy.

PubMed

Wang, Kun; Fan, Daoqing; Liu, Yaqing; Wang, Erkang

2015-11-15

Simple, rapid, sensitive and specific detection of cancer cells is of great importance for early and accurate cancer diagnostics and therapy. By coupling nanotechnology and dual-aptamer target binding strategies, we developed a colorimetric assay for visually detecting cancer cells with high sensitivity and specificity. The nanotechnology including high catalytic activity of PtAuNP and magnetic separation & concentration plays a vital role on the signal amplification and improvement of detection sensitivity. The color change caused by small amount of target cancer cells (10 cells/mL) can be clearly distinguished by naked eyes. The dual-aptamer target binding strategy guarantees the detection specificity that large amount of non-cancer cells and different cancer cells (10(4) cells/mL) cannot cause obvious color change. A detection limit as low as 10 cells/mL with detection linear range from 10 to 10(5) cells/mL was reached according to the experimental detections in phosphate buffer solution as well as serum sample. The developed enzyme-free and cost effective colorimetric assay is simple and no need of instrument while still provides excellent sensitivity, specificity and repeatability, having potential application on point-of-care cancer diagnosis. Copyright © 2015 Elsevier B.V. All rights reserved.

Impact of the time scale of model sensitivity response on coupled model parameter estimation

NASA Astrophysics Data System (ADS)

Liu, Chang; Zhang, Shaoqing; Li, Shan; Liu, Zhengyu

2017-11-01

That a model has sensitivity responses to parameter uncertainties is a key concept in implementing model parameter estimation using filtering theory and methodology. Depending on the nature of associated physics and characteristic variability of the fluid in a coupled system, the response time scales of a model to parameters can be different, from hourly to decadal. Unlike state estimation, where the update frequency is usually linked with observational frequency, the update frequency for parameter estimation must be associated with the time scale of the model sensitivity response to the parameter being estimated. Here, with a simple coupled model, the impact of model sensitivity response time scales on coupled model parameter estimation is studied. The model includes characteristic synoptic to decadal scales by coupling a long-term varying deep ocean with a slow-varying upper ocean forced by a chaotic atmosphere. Results show that, using the update frequency determined by the model sensitivity response time scale, both the reliability and quality of parameter estimation can be improved significantly, and thus the estimated parameters make the model more consistent with the observation. These simple model results provide a guideline for when real observations are used to optimize the parameters in a coupled general circulation model for improving climate analysis and prediction initialization.

A simple way to synthesize large-scale Cu2O/Ag nanoflowers for ultrasensitive surface-enhanced Raman scattering detection

NASA Astrophysics Data System (ADS)

Zou, Junyan; Song, Weijia; Xie, Weiguang; Huang, Bo; Yang, Huidong; Luo, Zhi

2018-03-01

Here, we report a simple strategy to prepare highly sensitive surface-enhanced Raman spectroscopy (SERS) substrates based on Ag decorated Cu2O nanoparticles by combining two common techniques, viz, thermal oxidation growth of Cu2O nanoparticles and magnetron sputtering fabrication of a Ag nanoparticle film. Methylene blue is used as the Raman analyte for the SERS study, and the substrates fabricated under optimized conditions have very good sensitivity (analytical enhancement factor ˜108), stability, and reproducibility. A linear dependence of the SERS intensities with the concentration was obtained with an R 2 value >0.9. These excellent properties indicate that the substrate has great potential in the detection of biological and chemical substances.

Sensitive detection of hydroxylamine at a simple baicalin carbon nanotubes modified electrode.

PubMed

Zhang, Hongfang; Zheng, Jianbin

2012-05-15

A baicalin multi-wall carbon nanotubes (BaMWCNT) modified glassy carbon electrode (GCE) for the sensitive determination of hydroxylamine was described. The BaMWCNT/GCE with dramatic stability was firstly fabricated with a simple adsorption method. And it showed excellent catalytic activity toward the electrooxidation of hydroxylamine. The amperometric response at the BaMWCNT/GCE modified electrode increased linearly to hydroxylamine concentrations in the range of 0.5 μM to 0.4mM with a detection limit of 0.1 μM. The modified electrode was applied to detection hydroxylamine in the tap water, and the average recovery for the standards added was 96.0%. Copyright © 2012 Elsevier B.V. All rights reserved.

Direct two-photon excitation of Sm3+, Eu3+, Tb3+, Tb.DOTA-, and Tb.propargylDO3A in solution

NASA Astrophysics Data System (ADS)

Sørensen, Thomas Just; Blackburn, Octavia A.; Tropiano, Manuel; Faulkner, Stephen

2012-07-01

We have observed direct two-photon excitation of samarium, europium and terbium ions in solution upon near IR excitation using a tuneable pulsed light source, and have also studied two-photon processes in a pair of related terbium complexes, namely [Tb.DOTA]- and Tb.propargylDO3A. Direct two-photon excitation of lanthanides is observed in simple systems in the absence of sensitizing chromophores. Where even simple chromophores such as a triple bond are present in the complex, then single and two-photon excitation of chromophore excited states competes with direct two-photon excitation of the ions and is the dominant pathway for sensitizing formation of the lanthanide excited state.

Clock Drawing Test and the diagnosis of amnestic mild cognitive impairment: can more detailed scoring systems do the work?

PubMed

Rubínová, Eva; Nikolai, Tomáš; Marková, Hana; Siffelová, Kamila; Laczó, Jan; Hort, Jakub; Vyhnálek, Martin

2014-01-01

The Clock Drawing Test is a frequently used cognitive screening test with several scoring systems in elderly populations. We compare simple and complex scoring systems and evaluate the usefulness of the combination of the Clock Drawing Test with the Mini-Mental State Examination to detect patients with mild cognitive impairment. Patients with amnestic mild cognitive impairment (n = 48) and age- and education-matched controls (n = 48) underwent neuropsychological examinations, including the Clock Drawing Test and the Mini-Mental State Examination. Clock drawings were scored by three blinded raters using one simple (6-point scale) and two complex (17- and 18-point scales) systems. The sensitivity and specificity of these scoring systems used alone and in combination with the Mini-Mental State Examination were determined. Complex scoring systems, but not the simple scoring system, were significant predictors of the amnestic mild cognitive impairment diagnosis in logistic regression analysis. At equal levels of sensitivity (87.5%), the Mini-Mental State Examination showed higher specificity (31.3%, compared with 12.5% for the 17-point Clock Drawing Test scoring scale). The combination of Clock Drawing Test and Mini-Mental State Examination scores increased the area under the curve (0.72; p < .001) and increased specificity (43.8%), but did not increase sensitivity, which remained high (85.4%). A simple 6-point scoring system for the Clock Drawing Test did not differentiate between healthy elderly and patients with amnestic mild cognitive impairment in our sample. Complex scoring systems were slightly more efficient, yet still were characterized by high rates of false-positive results. We found psychometric improvement using combined scores from the Mini-Mental State Examination and the Clock Drawing Test when complex scoring systems were used. The results of this study support the benefit of using combined scores from simple methods.

Psychophysical and perceptual performance in a simulated-scotoma model of human eye injury

NASA Astrophysics Data System (ADS)

Brandeis, R.; Egoz, I.; Peri, D.; Sapiens, N.; Turetz, J.

2008-02-01

Macular scotomas, affecting visual functioning, characterize many eye and neurological diseases like AMD, diabetes mellitus, multiple sclerosis, and macular hole. In this work, foveal visual field defects were modeled, and their effects were evaluated on spatial contrast sensitivity and a task of stimulus detection and aiming. The modeled occluding scotomas, of different size, were superimposed on the stimuli presented on the computer display, and were stabilized on the retina using a mono Purkinje Eye-Tracker. Spatial contrast sensitivity was evaluated using square-wave grating stimuli, whose contrast thresholds were measured using the method of constant stimuli with "catch trials". The detection task consisted of a triple conjunctive visual search display of: size (in visual angle), contrast and background (simple, low-level features vs. complex, high-level features). Search/aiming accuracy as well as R.T. measures used for performance evaluation. Artificially generated scotomas suppressed spatial contrast sensitivity in a size dependent manner, similar to previous studies. Deprivation effect was dependent on spatial frequency, consistent with retinal inhomogeneity models. Stimulus detection time was slowed in complex background search situation more than in simple background. Detection speed was dependent on scotoma size and size of stimulus. In contrast, visually guided aiming was more sensitive to scotoma effect in simple background search situation than in complex background. Both stimulus aiming R.T. and accuracy (precision targeting) were impaired, as a function of scotoma size and size of stimulus. The data can be explained by models distinguishing between saliency-based, parallel and serial search processes, guiding visual attention, which are supported by underlying retinal as well as neural mechanisms.

Understanding and comparisons of different sampling approaches for the Fourier Amplitudes Sensitivity Test (FAST)

PubMed Central

Xu, Chonggang; Gertner, George

2013-01-01

Fourier Amplitude Sensitivity Test (FAST) is one of the most popular uncertainty and sensitivity analysis techniques. It uses a periodic sampling approach and a Fourier transformation to decompose the variance of a model output into partial variances contributed by different model parameters. Until now, the FAST analysis is mainly confined to the estimation of partial variances contributed by the main effects of model parameters, but does not allow for those contributed by specific interactions among parameters. In this paper, we theoretically show that FAST analysis can be used to estimate partial variances contributed by both main effects and interaction effects of model parameters using different sampling approaches (i.e., traditional search-curve based sampling, simple random sampling and random balance design sampling). We also analytically calculate the potential errors and biases in the estimation of partial variances. Hypothesis tests are constructed to reduce the effect of sampling errors on the estimation of partial variances. Our results show that compared to simple random sampling and random balance design sampling, sensitivity indices (ratios of partial variances to variance of a specific model output) estimated by search-curve based sampling generally have higher precision but larger underestimations. Compared to simple random sampling, random balance design sampling generally provides higher estimation precision for partial variances contributed by the main effects of parameters. The theoretical derivation of partial variances contributed by higher-order interactions and the calculation of their corresponding estimation errors in different sampling schemes can help us better understand the FAST method and provide a fundamental basis for FAST applications and further improvements. PMID:24143037

Understanding and comparisons of different sampling approaches for the Fourier Amplitudes Sensitivity Test (FAST).

PubMed

Xu, Chonggang; Gertner, George

2011-01-01

Fourier Amplitude Sensitivity Test (FAST) is one of the most popular uncertainty and sensitivity analysis techniques. It uses a periodic sampling approach and a Fourier transformation to decompose the variance of a model output into partial variances contributed by different model parameters. Until now, the FAST analysis is mainly confined to the estimation of partial variances contributed by the main effects of model parameters, but does not allow for those contributed by specific interactions among parameters. In this paper, we theoretically show that FAST analysis can be used to estimate partial variances contributed by both main effects and interaction effects of model parameters using different sampling approaches (i.e., traditional search-curve based sampling, simple random sampling and random balance design sampling). We also analytically calculate the potential errors and biases in the estimation of partial variances. Hypothesis tests are constructed to reduce the effect of sampling errors on the estimation of partial variances. Our results show that compared to simple random sampling and random balance design sampling, sensitivity indices (ratios of partial variances to variance of a specific model output) estimated by search-curve based sampling generally have higher precision but larger underestimations. Compared to simple random sampling, random balance design sampling generally provides higher estimation precision for partial variances contributed by the main effects of parameters. The theoretical derivation of partial variances contributed by higher-order interactions and the calculation of their corresponding estimation errors in different sampling schemes can help us better understand the FAST method and provide a fundamental basis for FAST applications and further improvements.

The art of spacecraft design: A multidisciplinary challenge

NASA Technical Reports Server (NTRS)

Abdi, F.; Ide, H.; Levine, M.; Austel, L.

1989-01-01

Actual design turn-around time has become shorter due to the use of optimization techniques which have been introduced into the design process. It seems that what, how and when to use these optimization techniques may be the key factor for future aircraft engineering operations. Another important aspect of this technique is that complex physical phenomena can be modeled by a simple mathematical equation. The new powerful multilevel methodology reduces time-consuming analysis significantly while maintaining the coupling effects. This simultaneous analysis method stems from the implicit function theorem and system sensitivity derivatives of input variables. Use of the Taylor's series expansion and finite differencing technique for sensitivity derivatives in each discipline makes this approach unique for screening dominant variables from nondominant variables. In this study, the current Computational Fluid Dynamics (CFD) aerodynamic and sensitivity derivative/optimization techniques are applied for a simple cone-type forebody of a high-speed vehicle configuration to understand basic aerodynamic/structure interaction in a hypersonic flight condition.

Photonic crystal fiber-based plasmonic biosensor with external sensing approach

NASA Astrophysics Data System (ADS)

Rifat, Ahmmed A.; Hasan, Md. Rabiul; Ahmed, Rajib; Butt, Haider

2018-01-01

We propose a simple photonic crystal fiber (PCF) biosensor based on the surface plasmon resonance effect. The sensing properties are characterized using the finite element method. Chemically stable gold material is deposited on the outer surface of the PCF to realize the practical sensing approach. The performance of the modeled biosensor is investigated in terms of wavelength sensitivity, amplitude sensitivity, sensor resolution, and linearity of the resonant wavelength with the variation of structural parameters. In the sensing range of 1.33 to 1.37, maximum sensitivities of 4000 nm/RIU and 478 are achieved with the high sensor resolutions of 2.5×10-5 and 2.1×10-5 RIU using wavelength and amplitude interrogation methods, respectively. The designed biosensor will reduce fabrication complexity due to its simple and realistic hexagonal lattice structure. It is anticipated that the proposed biosensor may find possible applications for unknown biological and biochemical analyte detections with a high degree of accuracy.

Development of a rapid, simple and sensitive HPLC-FLD method for determination of rhodamine B in chili-containing products.

PubMed

Qi, Ping; Lin, Zhihao; Li, Jiaxu; Wang, ChengLong; Meng, WeiWei; Hong, Hong; Zhang, Xuewu

2014-12-01

In this work, a simple, rapid and sensitive analytical method for the determination of rhodamine B in chili-containing foodstuffs is described. The dye is extracted from samples with methanol and analysed without further cleanup procedure by high-performance liquid chromatography (HPLC) coupled to fluorescence detection (FLD). The influence of matrix fluorescent compounds (capsaicin and dihydrocapsaicin) on the analysis was overcome by the optimisation of mobile-phase composition. The limit of determination (LOD) and limit of quantification (LOQ) were 3.7 and 10 μg/kg, respectively. Validation data show a good repeatability and within-lab reproducibility with relative standard deviations <10%. The overall recoveries are in the range of 98-103% in chili powder and in the range of 87-100% in chili oil depending on the concentration of rhodamine B in foodstuffs. This method is suitable for the routine analysis of rhodamine B due to its sensitivity, simplicity, reasonable time and cost. Copyright © 2014 Elsevier Ltd. All rights reserved.

Quantitative determination of some pharmaceutical piperazine derivatives through complexation with iron(III) chloride.

PubMed

Abou-Attia, F M; Issa, Y M; Abdel-Gawad, F M; Abdel-Hamid, S M

2003-08-01

A simple, accurate and sensitive spectrophotometric method has been developed for the determination of three pharmaceutical piperazine derivatives, namely ketoconazole (KC), trimetazidine hydrochloride (TMH) and piribedil (PD). This method is based on the formation of yellow orange complexes between iron(III) chloride and the investigated drugs. The optimum reaction conditions, spectral characteristics, conditional stability constants and composition of the water soluble complexes have been established. The method permits the determination of KC, TMH and PD over a concentration range 1-15, 1-12 and 1-12 microg ml(-1), respectively. Sandell sensitivity is found to be 0.016, 0.013 and 0.013 microg cm(-2) for KC, TMH and PD, respectively. The method was sensitive, simple, reproducible and accurate within +/-1.5%. The method is applicable to the assay of the three drugs under investigation in different dosage forms and the results are in good agreement with those obtained by the official methods (USP and JP).

The impact of secondary-task type on the sensitivity of reaction-time based measurement of cognitive load for novices learning surgical skills using simulation.

PubMed

Rojas, David; Haji, Faizal; Shewaga, Rob; Kapralos, Bill; Dubrowski, Adam

2014-01-01

Interest in the measurement of cognitive load (CL) in simulation-based education has grown in recent years. In this paper we present two pilot experiments comparing the sensitivity of two reaction time based secondary task measures of CL. The results suggest that simple reaction time measures are sensitive enough to detect changes in CL experienced by novice learners in the initial stages of simulation-based surgical skills training.

On the Exploitation of Sensitivity Derivatives for Improving Sampling Methods

NASA Technical Reports Server (NTRS)

Cao, Yanzhao; Hussaini, M. Yousuff; Zang, Thomas A.

2003-01-01

Many application codes, such as finite-element structural analyses and computational fluid dynamics codes, are capable of producing many sensitivity derivatives at a small fraction of the cost of the underlying analysis. This paper describes a simple variance reduction method that exploits such inexpensive sensitivity derivatives to increase the accuracy of sampling methods. Three examples, including a finite-element structural analysis of an aircraft wing, are provided that illustrate an order of magnitude improvement in accuracy for both Monte Carlo and stratified sampling schemes.

STARLSE -- Starlink Extensions to the VAX Language Sensitive Editor

NASA Astrophysics Data System (ADS)

Warren-Smith, R. F.

STARLSE is a ``Starlink Sensitive'' editor based on the VAX Language Sensitive Editor (LSE). It exploits the extensibility of LSE to provide additional features which assist in the writing of portable Fortran 77 software with a standard Starlink style. STARLSE is intended mainly for use by those writing ADAM applications and subroutine libraries for distribution as part of the Starlink Software Collection, although it may also be suitable for other software projects. It is designed to integrate with the SST (Simple Software Tools) package.

Chromosomal Aberrations in DNA Repair Defective Cell Lines: Comparisons of Dose Rate and Radiation Quality

NASA Technical Reports Server (NTRS)

George, K. A.; Hada, M.; Patel, Z.; Huff, J.; Pluth, J. M.; Cucinotta, F. A.

2009-01-01

Chromosome aberration yields were assessed in DNA double-strand break repair (DSB) deficient cells after acute doses of gamma-rays or high-LET iron nuclei, or low dose-rate (0.018 Gy/hr) gamma-rays. We studied several cell lines including fibroblasts deficient in ATM (product of the gene that is mutated in ataxia telangiectasia patients) or NBS (product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase, DNA-PK activity. Chromosomes were analyzed using the fluorescence in-situ hybridization (FISH) chromosome painting method in cells at the first division post-irradiation and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma radiation induced higher yields of both simple and complex exchanges in the DSB repair defective cells than in the normal cells. The quadratic dose-response terms for both chromosome exchange types were significantly higher for the ATM and NBS defective lines than for normal fibroblasts. However, the linear dose-response term was significantly higher only for simple exchanges in the NBS cells. Large increases in the quadratic dose response terms indicate the important roles of ATM and NBS in chromatin modifications that facilitate correct DSB repair and minimize aberration formation. Differences in the response of AT and NBS deficient cells at lower doses suggests important questions about the applicability of observations of radiation sensitivity at high dose to low dose exposures. For all iron nuclei irradiated cells, regression models preferred purely linear and quadratic dose responses for simple and complex exchanges, respectively. All the DNA repair defective cell lines had lower Relative biological effectiveness (RBE) values than normal cells, the lowest being for the DNA-PK-deficient cells, which was near unity. To further investigate the sensitivity differences for low and low high doses, we performed chronic low dose-rate irradiation, and have begun studies with ATM and Nibrin inhibitors and siRNA knockout of these proteins. Results support the conclusion that for the endpoint of simple chromosomal aberrations (translocation or dicentrics), the increased radiation sensitivity of AT cells found at high doses (>1 Gy) does not carry over to low doses or doserates, while NBS cells show increased sensitivity for both high and low dose exposures.

Noninvasive Tests Do Not Accurately Differentiate Nonalcoholic Steatohepatitis From Simple Steatosis: A Systematic Review and Meta-analysis.

PubMed

Verhaegh, Pauline; Bavalia, Roisin; Winkens, Bjorn; Masclee, Ad; Jonkers, Daisy; Koek, Ger

2018-06-01

Nonalcoholic fatty liver disease is a rapidly increasing health problem. Liver biopsy analysis is the most sensitive test to differentiate between nonalcoholic steatohepatitis (NASH) and simple steatosis (SS), but noninvasive methods are needed. We performed a systematic review and meta-analysis of noninvasive tests for differentiating NASH from SS, focusing on blood markers. We performed a systematic search of the PubMed, Medline and Embase (1990-2016) databases using defined keywords, limited to full-text papers in English and human adults, and identified 2608 articles. Two independent reviewers screened the articles and identified 122 eligible articles that used liver biopsy as reference standard. If at least 2 studies were available, pooled sensitivity (sens p ) and specificity (spec p ) values were determined using the Meta-Analysis Package for R (metafor). In the 122 studies analyzed, 219 different blood markers (107 single markers and 112 scoring systems) were identified to differentiate NASH from simple steatosis, and 22 other diagnostic tests were studied. Markers identified related to several pathophysiological mechanisms. The markers analyzed in the largest proportions of studies were alanine aminotransferase (sens p , 63.5% and spec p , 74.4%) within routine biochemical tests, adiponectin (sensp, 72.0% and spec p , 75.7%) within inflammatory markers, CK18-M30 (sens p , 68.4% and spec p , 74.2%) within markers of cell death or proliferation and homeostatic model assessment of insulin resistance (sens p , 69.0% and spec p , 72.7%) within the metabolic markers. Two scoring systems could also be pooled: the NASH test (differentiated NASH from borderline NASH plus simple steatosis with 22.9% sens p and 95.3% spec p ) and the GlycoNASH test (67.1% sens p and 63.8% spec p ). In the meta-analysis, we found no test to differentiate NASH from SS with a high level of pooled sensitivity and specificity (≥80%). However, some blood markers, when included in scoring systems in single studies, identified patients with NASH with ≥80% sensitivity and specificity. Replication studies and more standardized study designs are urgently needed. At present, no marker or scoring system can be recommended for use in clinical practice to differentiate NASH from simple steatosis. Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.

A simple sensing mechanism for wireless, passive pressure sensors.

PubMed

Drazan, John F; Wassick, Michael T; Dahle, Reena; Beardslee, Luke A; Cady, Nathaniel C; Ledet, Eric H

2016-08-01

We have developed a simple wireless pressure sensor that consists of only three electrically isolated components. Two conductive spirals are separated by a closed cell foam that deforms when exposed to changing pressures. This deformation changes the capacitance and thus the resonant frequency of the sensors. Prototype sensors were submerged and wirelessly interrogated while being exposed to physiologically relevant pressures from 10 to 130 mmHg. Sensors consistently exhibited a sensitivity of 4.35 kHz/mmHg which is sufficient for resolving physiologically relevant pressure changes in vivo. These simple sensors have the potential for in vivo pressure sensing.

IOTA simple rules in differentiating between benign and malignant ovarian tumors.

PubMed

Tantipalakorn, Charuwan; Wanapirak, Chanane; Khunamornpong, Surapan; Sukpan, Kornkanok; Tongsong, Theera

2014-01-01

To evaluate the diagnostic performance of IOTA simple rules in differentiating between benign and malignant ovarian tumors. A study of diagnostic performance was conducted on women scheduled for elective surgery due to ovarian masses between March 2007 and March 2012. All patients underwent ultrasound examination for IOTA simple rules within 24 hours of surgery. All examinations were performed by the authors, who had no any clinical information of the patients, to differentiate between benign and malignant adnexal masses using IOTA simple rules. Gold standard diagnosis was based on pathological or operative findings. A total of 398 adnexal masses, in 376 women, were available for analysis. Of them, the IOTA simple rules could be applied in 319 (80.1%) including 212 (66.5%) benign tumors and 107 (33.6%) malignant tumors. The simple rules yielded inconclusive results in 79 (19.9%) masses. In the 319 masses for which the IOTA simple rules could be applied, sensitivity was 82.9% and specificity 95.3%. The IOTA simple rules have high diagnostic performance in differentiating between benign and malignant adnexal masses. Nevertheless, inconclusive results are relatively common.

A Simple and Reliable Method for Hybridization of Homothallic Wine Strains of Saccharomyces cerevisiae

PubMed Central

Ramírez, Manuel; Peréz, Francisco; Regodón, José A.

1998-01-01

A procedure was developed for the hybridization and improvement of homothallic industrial wine yeasts. Killer cycloheximide-sensitive strains were crossed with killer-sensitive cycloheximide-resistant strains to get killer cycloheximide-resistant hybrids, thereby enabling hybrid selection and identification. This procedure also allows backcrossing of spore colonies from the hybrids with parental strains. PMID:9835605

A simple and rapid DNA extraction method for Chlamydia trachomatis detection from urogenital swabs.

PubMed

Butzler, Matthew A; Reed, Jennifer L; McFall, Sally M

2017-11-01

A highly sensitive and specific Chlamydia trachomatis (CT) diagnostic test was developed by combining filtration isolation of nucleic acid (FINA) extraction with quantitative polymerase chain reaction including an internal control to identify test inhibition. A pilot study of 40 clinical specimens yielded 100% sensitivity and specificity. Copyright © 2017 Elsevier Inc. All rights reserved.

The Game of Life Rules on Penrose Tilings: Still Life and Oscillators

NASA Astrophysics Data System (ADS)

Owens, Nick; Stepney, Susan

John Horton Conway's Game of Life is a simple two-dimensional, two state cellular automaton (CA), remarkable for its complex behaviour. That behaviour is known to be very sensitive to a change in the CA rules. Here we continue our investigations into its sensitivity to changes in the lattice, by the use of an aperiodic Penrose tiling lattice.

pyZELDA: Python code for Zernike wavefront sensors

NASA Astrophysics Data System (ADS)

Vigan, A.; N'Diaye, M.

2018-06-01

pyZELDA analyzes data from Zernike wavefront sensors dedicated to high-contrast imaging applications. This modular software was originally designed to analyze data from the ZELDA wavefront sensor prototype installed in VLT/SPHERE; simple configuration files allow it to be extended to support several other instruments and testbeds. pyZELDA also includes simple simulation tools to measure the theoretical sensitivity of a sensor and to compare it to other sensors.

A simple and sensitive enzymatic method for cholesterol quantification in macrophages and foam cells

PubMed Central

Robinet, Peggy; Wang, Zeneng; Hazen, Stanley L.; Smith, Jonathan D.

2010-01-01

A precise and sensitive method for measuring cellular free and esterified cholesterol is required in order to perform studies of macrophage cholesterol loading, metabolism, storage, and efflux. Until now, the use of an enzymatic cholesterol assay, commonly used for aqueous phase plasma cholesterol assays, has not been optimized for use with solid phase samples such as cells, due to inefficient solubilization of total cholesterol in enzyme compatible solvents. We present an efficient solubilization protocol compatible with an enzymatic cholesterol assay that does not require chemical saponification or chromatographic separation. Another issue with enzyme compatible solvents is the presence of endogenous peroxides that interfere with the enzymatic cholesterol assay. We overcame this obstacle by pretreatment of the reaction solution with the enzyme catalase, which consumed endogenous peroxides resulting in reduced background and increased sensitivity in our method. Finally, we demonstrated that this method for cholesterol quantification in macrophages yields results that are comparable to those measured by stable isotope dilution gas chromatography with mass spectrometry detection. In conclusion, we describe a sensitive, simple, and high-throughput enzymatic method to quantify cholesterol in complex matrices such as cells. PMID:20688754

A visual assay and spectrophotometric determination of LLM-105 explosive using detection of gold nanoparticle aggregation at two pH values.

PubMed

He, Yi; Cheng, Yang

2016-08-01

We report a simple, rapid, and sensitive assay for visual and spectrophotometric detection of the 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) explosive. The assay is based on different interactions between LLM-105 and gold nanoparticle (AuNP) dispersions at two pH values, leading to the formation of dispersed or aggregated AuNPs. Two AuNP dispersions at two pH values were applied to recognize and detect LLM-105 instead of traditional AuNP dispersion under an aptotic pH to improve the anti-interference ability. The developed assay showed excellent sensitivity with a detection limit of 3 ng/mL, and the presence of as low as 0.2 μg/mL LLM-105 can be directly detected with the bare eye. This sensitivity is about six orders of magnitude higher than that of the reported traditional assays. Additionally, the assay exhibited good selectivity toward LLM-105 over other explosives, sulfur-containing compounds, and amines. Graphical abstract A simple, sensitive, and selective assay for LLM-105 was developed based on the pH-dependent interaction between the LLM-105 explosive and gold nanoparticle dispersion.

A simple and rapid DNA extraction method from whole blood for highly sensitive detection and quantitation of HIV-1 proviral DNA by real-time PCR.

PubMed

McFall, Sally M; Wagner, Robin L; Jangam, Sujit R; Yamada, Douglas H; Hardie, Diana; Kelso, David M

2015-03-01

Early diagnosis and access to treatment for infants with human immunodeficiency virus-1 (HIV-1) is critical to reduce infant mortality. The lack of simple point-of-care tests impedes the timely initiation of antiretroviral therapy. The development of FINA, filtration isolation of nucleic acids, a novel DNA extraction method that can be performed by clinic personnel in less than 2 min has been reported previously. In this report, significant improvements in the DNA extraction and amplification methods are detailed that allow sensitive quantitation of as little as 10 copies of HIV-1 proviral DNA and detection of 3 copies extracted from 100 μl of whole blood. An internal control to detect PCR inhibition was also incorporated. In a preliminary field evaluation of 61 South African infants, the FINA test demonstrated 100% sensitivity and specificity. The proviral copy number of the infant specimens was quantified, and it was established that 100 microliters of whole blood is required for sensitive diagnosis of infants. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

A Simple Model of Global Aerosol Indirect Effects

NASA Technical Reports Server (NTRS)

Ghan, Steven J.; Smith, Steven J.; Wang, Minghuai; Zhang, Kai; Pringle, Kirsty; Carslaw, Kenneth; Pierce, Jeffrey; Bauer, Susanne; Adams, Peter

2013-01-01

Most estimates of the global mean indirect effect of anthropogenic aerosol on the Earth's energy balance are from simulations by global models of the aerosol lifecycle coupled with global models of clouds and the hydrologic cycle. Extremely simple models have been developed for integrated assessment models, but lack the flexibility to distinguish between primary and secondary sources of aerosol. Here a simple but more physically based model expresses the aerosol indirect effect (AIE) using analytic representations of cloud and aerosol distributions and processes. Although the simple model is able to produce estimates of AIEs that are comparable to those from some global aerosol models using the same global mean aerosol properties, the estimates by the simple model are sensitive to preindustrial cloud condensation nuclei concentration, preindustrial accumulation mode radius, width of the accumulation mode, size of primary particles, cloud thickness, primary and secondary anthropogenic emissions, the fraction of the secondary anthropogenic emissions that accumulates on the coarse mode, the fraction of the secondary mass that forms new particles, and the sensitivity of liquid water path to droplet number concentration. Estimates of present-day AIEs as low as 5 W/sq m and as high as 0.3 W/sq m are obtained for plausible sets of parameter values. Estimates are surprisingly linear in emissions. The estimates depend on parameter values in ways that are consistent with results from detailed global aerosol-climate simulation models, which adds to understanding of the dependence on AIE uncertainty on uncertainty in parameter values.

Analysis of bacterial migration. 2: Studies with multiple attractant gradients

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

Strauss, I.; Frymier, P.D.; Hahn, C.M.

1995-02-01

Many motile bacteria exhibit chemotaxis, the ability to bias their random motion toward or away from increasing concentrations of chemical substances which benefit or inhibit their survival, respectively. Since bacteria encounter numerous chemical concentration gradients simultaneously in natural surroundings, it is necessary to know quantitatively how a bacterial population responds in the presence of more than one chemical stimulus to develop predictive mathematical models describing bacterial migration in natural systems. This work evaluates three hypothetical models describing the integration of chemical signals from multiple stimuli: high sensitivity, maximum signal, and simple additivity. An expression for the tumbling probability for individualmore » stimuli is modified according to the proposed models and incorporated into the cell balance equation for a 1-D attractant gradient. Random motility and chemotactic sensitivity coefficients, required input parameters for the model, are measured for single stimulus responses. Theoretical predictions with the three signal integration models are compared to the net chemotactic response of Escherichia coli to co- and antidirectional gradients of D-fucose and [alpha]-methylaspartate in the stopped-flow diffusion chamber assay. Results eliminate the high-sensitivity model and favor the simple additivity over the maximum signal. None of the simple models, however, accurately predict the observed behavior, suggesting a more complex model with more steps in the signal processing mechanism is required to predict responses to multiple stimuli.« less

Atmospheric correction of ocean color sensors: analysis of the effects of residual instrument polarization sensitivity.

PubMed

Gordon, H R; Du, T; Zhang, T

1997-09-20

We provide an analysis of the influence of instrument polarization sensitivity on the radiance measured by spaceborne ocean color sensors. Simulated examples demonstrate the influence of polarization sensitivity on the retrieval of the water-leaving reflectance rho(w). A simple method for partially correcting for polarization sensitivity--replacing the linear polarization properties of the top-of-atmosphere reflectance with those from a Rayleigh-scattering atmosphere--is provided and its efficacy is evaluated. It is shown that this scheme improves rho(w) retrievals as long as the polarization sensitivity of the instrument does not vary strongly from band to band. Of course, a complete polarization-sensitivity characterization of the ocean color sensor is required to implement the correction.

Sparteine monooxygenase in brain and liver: Identified by the dopamine uptake blocker ( sup 3 H)GBR-12935

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

Kalow, W.; Tyndale, R.F.; Niznik, H.B.

1990-02-26

P450IID6 (human sparteine monooxygenase) metabolizes many drugs including neuroleptics, antidepressants, and beta-blockers. The P450IID6 exists in human, bovine, rat and canine brains, but in very low quantities causing methodological difficulties in its assessment. Work with ({sup 3}H)GBR-12935; 1-(2-(diphenylmethoxy) ethyl)-4-(3-phenyl propyl) piperazine has shown that it binds a neuronal/hepatic protein with high affinity ({approximately}7nM) and a rank order of inhibitory potency suggesting that the binding protein is cytochrome P450IID6. The binding was used to predict that d-amphetamine and methamphetamine would interact with P450IID6. Inhibition studies indicated that these compounds were competitive inhibitors of P450IID6. Haloperidol (HAL) and it's metabolite hydroxy-haloperidol (RHAL)more » are both competitive inhibitors of P450IID6 activity and were found to inhibit ({sup 3}H)GBR-12935 binding. K{sub i} values of twelve compounds (known to interact with the DA transporter or P450IID6) for ({sup 3}H)GRB-12935 binding and P450IID6 activity. The techniques are now available for measurements of cytochrome P450IID6 in healthy and diseased brain/liver tissue using radio-receptor binding assay techniques with ({sup 3}H)GBR-12935.« less

Focal adhesion kinase dependent activation of the PI3 kinase pathway by the functional soluble form of neurotensin receptor-3 in HT29 cells.

PubMed

Massa, Fabienne; Devader, Christelle; Béraud-Dufour, Sophie; Brau, Frédéric; Coppola, Thierry; Mazella, Jean

2013-05-01

The neurotensin (NT) receptor-3 (NTSR3), also called sortilin, is thought to display several functions including a role as a receptor or a co-receptor, in the sorting to plasma membrane and to lysosomes, and in the regulated secretion. The aim of this study was to investigate the function of the soluble form of NTSR3 (sNTSR3) released from several cell lines including colonic cancer cells. The human adenocarcinoma epithelial cell line HT29 has been used to monitor the release, the binding and internalization of sNTSR3 by radioreceptor assays and confocal microscopy. The modulation of the intracellular signaling pathways by the protein has been investigated by using Fura-2 fluorescence calcium imaging microscopy and Western blots analysis. We demonstrated that sNTSR3 specifically binds and internalizes into HT29 cells. This binding, independent from the transactivation of the epidermal growth factor receptor, leads to the increase of intracellular calcium concentration and to the activation of a FAK/Src-dependent activation of the PI3 kinase pathway. In conclusion, sNTSR3 released from the membrane bound NTSR3 is a functional protein able to activate intracellular pathways involved in cell survival but probably not in cell growth. Copyright © 2013 Elsevier Ltd. All rights reserved.

Anxiety-like behavior in transgenic mice with brain expression of neuropeptide Y.

PubMed

Inui, A; Okita, M; Nakajima, M; Momose, K; Ueno, N; Teranishi, A; Miura, M; Hirosue, Y; Sano, K; Sato, M; Watanabe, M; Sakai, T; Watanabe, T; Ishida, K; Silver, J; Baba, S; Kasuga, M

1998-01-01

Neuropeptide Y (NPY), one of the most abundant peptide transmitters in the mammalian brain, is assumed to play an important role in behavior and its disorders. To understand the long-term modulation of neuronal functions by NPY, we raised transgenic mice created with a novel central nervous system (CNS) neuron-specific expression vector of human Thy- gene fragment linked to mouse NPY cDNA. In situ hybridization analysis demonstrated transgene-derived NPY expression in neurons (e.g., in the hippocampus, cerebral cortex, and the arcuate nucleus of the hypothalamus) in the transgenic mice. The modest increase of NPY protein in the brain was demonstrated by semiquantitative immunohistochemical analysis and by radioreceptor assay (115% in transgenic mice compared to control littermates). Double-staining experiments indicated colocalization of the transgene-derived NPY message and NPY protein in the same neurons, such as in the arcuate nucleus. The transgenic mice displayed behavioral signs of anxiety and hypertrophy of adrenal zona fasciculata cells, but no change in food intake was observed. The anxiety-like behavior of transgenic mice was reversed, at least in part, by administration of corticotropin-releasing factor (CRF) antagonists, alpha-helical CRF9-41, into the third cerebral ventricle. These results suggest that NPY has a role in anxiety and behavioral responses to stress partly via the CRF neuronal system. This genetic model may provide a unique opportunity to study human anxiety and emotional disorders.

Expression of cholinergic, insulin, vitamin D receptors and GLUT 3 in the brainstem of streptozotocin induced diabetic rats: effect of treatment with vitamin D₃.

PubMed

Peeyush Kumar, T; Paul, Jes; Antony, Sherin; Paulose, C S

2011-11-01

Complications arising from diabetes mellitus include cognitive deficits, neurophysiological and structural changes in the brain. The current study investigated the expression of cholinergic, insulin, Vitamin D receptor and GLUT 3 in the brainstem of streptozotocin-induced diabetic rats. Radioreceptor binding assays and gene expression were done in the brainstem of male Wistar rats. Our results showed that B(max) of total muscarinic, muscarinic M3 receptors was increased and muscarinic M1 receptor was decreased in diabetic rats compared to control. A significant increase in gene expression of muscarinic M3, α7 nicotinic acetylcholine, insulin, Vitamin D₃ receptors, acetylcholine esterase, choline acetyl transferase and GLUT 3 were observed in the brainstem of diabetic rats. Immunohistochemistry studies of muscarinic M1, M3 and α7 nicotinic acetylcholine receptors confirmed the gene expression at protein level. Vitamin D₃ and insulin treatment reversed diabetes-induced alterations to near control. This study provides an evidence that diabetes can alter the expression of cholinergic, insulin, Vitamin D receptors and GLUT 3 in brainstem. We found that Vitamin D₃ treatment could modulate the Vitamin D receptors and plays a pivotal role in maintaining the glucose transport and expressional level of cholinergic receptors in the brainstem of diabetic rats. Thus, our results suggest a therapeutic role of Vitamin D₃ in managing neurological disorders associated with diabetes.

A dual amplification strategy for DNA detection combining bio-barcode assay and metal-enhanced fluorescence modality.

PubMed

Zhou, Zhenpeng; Li, Tian; Huang, Hongduan; Chen, Yang; Liu, Feng; Huang, Chengzhi; Li, Na

2014-11-11

Silver-enhanced fluorescence was coupled with a bio-barcode assay to facilitate a dual amplification assay to demonstrate a non-enzymatic approach for simple and sensitive detection of DNA. In the assay design, magnetic nanoparticles seeded with silver nanoparticles were modified with the capture DNA, and silver nanoparticles were modified with the binding of ssDNA and the fluorescently labeled barcode dsDNA. Upon introduction of the target DNA, a sandwich structure was formed because of the hybridization reaction. By simple magnetic separation, silver-enhanced fluorescence of barcode DNAs could be readily measured without the need of a further step to liberate barcode DNAs from silver nanoparticles, endowing the method with simplicity and high sensitivity with a detection limit of 1 pM.

A rapid and simple method of detection of Blepharisma japonicum using PCR and immobilisation on FTA paper

PubMed Central

Hide, Geoff; Hughes, Jacqueline M; McNuff, Robert

2003-01-01

Background The rapid expansion in the availability of genome and DNA sequence information has opened up new possibilities for the development of methods for detecting free-living protozoa in environmental samples. The protozoan Blepharisma japonicum was used to investigate a rapid and simple detection system based on polymerase chain reaction amplification (PCR) from organisms immobilised on FTA paper. Results Using primers designed from the α-tubulin genes of Blepharisma, specific and sensitive detection to the equivalent of a single Blepharisma cell could be achieved. Similar detection levels were found using water samples, containing Blepharisma, which were dried onto Whatman FTA paper. Conclusion This system has potential as a sensitive convenient detection system for Blepharisma and could be applied to other protozoan organisms. PMID:14516472

ZnO Hierarchical Nanostructure Photoanode in a CdS Quantum Dot-Sensitized Solar Cell

PubMed Central

Liu, Huan; Zhang, Gengmin; Sun, Wentao; Shen, Ziyong; Shi, Mingji

2015-01-01

A hierarchical array of ZnO nanocones covered with ZnO nanospikes was hydrothermally fabricated and employed as the photoanode in a CdS quantum dot-sensitized solar cell (QDSSC). This QDSSC outperformed the QDSSC based on a simple ZnO nanocone photoanode in all the four principal photovoltaic parameters. Using the hierarchical photoanode dramatically increased the short circuit current density and also slightly raised the open circuit voltage and the fill factor. As a result, the conversion efficiency of the QDSSC based on the hierarchical photoanode was more than twice that of the QDSSC based on the simple ZnO nanocone photoanode. This improvement is attributable to both the enlarged specific area of the photoanode and the reduction in the recombination of the photoexcited electrons. PMID:26379268

Novel fabrication of flexible graphene-based chemical sensors with heaters using soft lithographic patterning method.

PubMed

Jung, Min Wook; Myung, Sung; Song, Wooseok; Kang, Min-A; Kim, Sung Ho; Yang, Cheol-Soo; Lee, Sun Sook; Lim, Jongsun; Park, Chong-Yun; Lee, Jeong-O; An, Ki-Seok

2014-08-27

We have fabricated graphene-based chemical sensors with flexible heaters for the highly sensitive detection of specific gases. We believe that increasing the temperature of the graphene surface significantly enhanced the electrical signal change of the graphene-based channel, and reduced the recovery time needed to obtain a normal state of equilibrium. In addition, a simple and efficient soft lithographic patterning process was developed via surface energy modification for advanced, graphene-based flexible devices, such as gas sensors. As a proof of concept, we demonstrated the high sensitivity of NO2 gas sensors based on graphene nanosheets. These devices were fabricated using a simple soft-lithographic patterning method, where flexible graphene heaters adjacent to the channel of sensing graphene were utilized to control graphene temperature.

Simple detection of residual enrofloxacin in meat products using microparticles and biochips.

PubMed

Ha, Mi-Sun; Chung, Myung-Sub; Bae, Dong-Ho

2016-05-01

A simple and sensitive method for detecting enrofloxacin, a major veterinary fluoroquinolone, was developed. Monoclonal antibody specific for enrofloxacin was immobilised on a chip and fluorescent dye-labelled microparticles were covalently bound to the enrofloxacin molecules. Enrofloxacin in solution competes with the microparticle-immobilised enrofloxacin (enroMPs) to bind to the antibody on the chip. The presence of enrofloxacin was verified by detecting the fluorescence of enrofloxacin-bound microparticles. Under optimum conditions, a high dynamic range was achieved at enrofloxacin concentrations ranging from 1 to 1000 μg kg(-1). The limits of detection and quantification for standard solutions were 5 and 20 μg kg(-1) respectively, which are markedly lower than the maximum residue limit. Using simple extraction methods, recoveries from fortified beef, pork and chicken samples were 43.4-62.3%. This novel method also enabled approximate quantification of enrofloxacin concentration: the enroMP signal intensity decreased with increasing enrofloxacin concentration. Because of its sensitivity, specificity, simplicity and rapidity, the method described herein will facilitate the detection and approximate quantification of enrofloxacin residues in foods in a high-throughput manner.

Standardizing a simpler, more sensitive and accurate tail bleeding assay in mice

PubMed Central

Liu, Yang; Jennings, Nicole L; Dart, Anthony M; Du, Xiao-Jun

2012-01-01

AIM: To optimize the experimental protocols for a simple, sensitive and accurate bleeding assay. METHODS: Bleeding assay was performed in mice by tail tip amputation, immersing the tail in saline at 37 °C, continuously monitoring bleeding patterns and measuring bleeding volume from changes in the body weight. Sensitivity and extent of variation of bleeding time and bleeding volume were compared in mice treated with the P2Y receptor inhibitor prasugrel at various doses or in mice deficient of FcRγ, a signaling protein of the glycoprotein VI receptor. RESULTS: We described details of the bleeding assay with the aim of standardizing this commonly used assay. The bleeding assay detailed here was simple to operate and permitted continuous monitoring of bleeding pattern and detection of re-bleeding. We also reported a simple and accurate way of quantifying bleeding volume from changes in the body weight, which correlated well with chemical assay of hemoglobin levels (r2 = 0.990, P < 0.0001). We determined by tail bleeding assay the dose-effect relation of the anti-platelet drug prasugrel from 0.015 to 5 mg/kg. Our results showed that the correlation of bleeding time and volume was unsatisfactory and that compared with the bleeding time, bleeding volume was more sensitive in detecting a partial inhibition of platelet’s haemostatic activity (P < 0.01). Similarly, in mice with genetic disruption of FcRγ as a signaling molecule of P-selectin glycoprotein ligand-1 leading to platelet dysfunction, both increased bleeding volume and repeated bleeding pattern defined the phenotype of the knockout mice better than that of a prolonged bleeding time. CONCLUSION: Determination of bleeding pattern and bleeding volume, in addition to bleeding time, improved the sensitivity and accuracy of this assay, particularly when platelet function is partially inhibited. PMID:24520531

Antibody conjugated glycine doped polyaniline nanofilms as efficient biosensor for atrazine

NASA Astrophysics Data System (ADS)

Bhardwaj, Sanjeev K.; Sharma, Amit L.; Kim, Ki-Hyun; Deep, Akash

2017-12-01

Atrazine is an important member of triazine family of pesticides. The development of its detection methods gained great attention due to the potential health risks associated with its contamination in various media including water, soil, and food. The contamination of atrazine in drinking water beyond the legal permissible limit of EPA (e.g. 3 ng ml-1) may cause various damages to living organisms (e.g. heart, urinary, and limb defects). In this research, we discuss the potential significance of a highly sensitive conductometric immunosensor for sensing the atrazine pesticide. To this end, electrochemical assembly of glycine doped polyaniline (PAni) nanofilms on silicon (Si) substrate was built and modified further with anti-atrazine antibodies. The herein developed immunosensor offered highly sensitive detection of atrazine with a low detection limit of 0.07 ng ml-1. The proposed biosensor was simple in design with excellent performance in terms of its sensitivity, stability and specificity. Highlights •Glycine doped PAni nanofilms have been electropolymerized on Silicon substrates. •Functionality of the above thin films provides opportunity to develop an immunosensing platform. •Highly sensitive and specific detection of atrazine has been realized over a wide concentration range with a LOD of 0.07 ng ml-1. Novelty statement Atrazine is a widely used pesticide in the agriculture sector. It is highly recommended to develop simple biosensing systems for enabling the prospect of routine monitoring. The present research for the first time proposes the design of a glycine doped PAni based simple and highly effective biosensor for the atrazine pesticide. The doping of glycine has easily generated functional groups on the nano-PAni material for further convenient immobilization of anti-atrazine antibodies. The proposed sensor can be highlighted with advantages like ease of fabrication, use of environment friendly functionalization agent, specificity, wide linearity, and good sensitivity with enhanced viability.

Based on time and spatial-resolved SERS mapping strategies for detection of pesticides.

PubMed

Ma, Bingbing; Li, Pan; Yang, Liangbao; Liu, Jinhuai

2015-08-15

For the sensitive and convenient detection of pesticides, several sensing methods and materials have been widely explored. However, it is still a challenge to obtain sensitive, simple detection techniques for pesticides. Here, the simple and sensitive Time-resolved SERS mapping (T-SERS) and Spatial-resolved SERS mapping (S-SERS) are presented for detection of pesticides by using Au@Ag NPs as SERS substrate. The Time-resolved SERS mapping (T-SERS) is based on state translation nanoparticles from the wet state to the dry state to realize SERS measurements. During the SERS measurement, adhesive force drives the particles closer together and then average interparticle gap becomes smaller. Following, air then begins to intersperse into the liquid network and the particles are held together by adhesive forces at the solid-liquid-air interface. In the late stage of water evaporation, all particles are uniformly distributed. Thus, so called hotspots matrix that can hold hotspots between every two adjacent particles in efficient space with minimal polydispersity of particle size are achieved, accompanying the red-shift of surface plasmon peak and appearance of an optimal SPR resonated sharply with excitation wavelength. Here, we found that the T-SERS method exhibits the detection limits of 1-2 orders of magnitude higher than that of S-SERS. On the other hand, the T-SERS is very simple method with high detection sensitivity, better reproducibility (RSD=10.8%) and is beneficial to construction of a calibration curve in comparison with that of Spatial-resolved SERS mapping (S-SERS). Most importantly, as a result of its remarkable sensitivity, T-SERS mapping strategies have been applied to detection of several pesticides and the detect limit can down to 1nM for paraoxon, 0.5nM for sumithion. In short, T-SERS mapping measurement promises to open a market for SERS practical detection with prominent advantages. Copyright © 2015. Published by Elsevier B.V.

Simplification and its consequences in biological modelling: conclusions from a study of calcium oscillations in hepatocytes.

PubMed

Hetherington, James P J; Warner, Anne; Seymour, Robert M

2006-04-22

Systems Biology requires that biological modelling is scaled up from small components to system level. This can produce exceedingly complex models, which obscure understanding rather than facilitate it. The successful use of highly simplified models would resolve many of the current problems faced in Systems Biology. This paper questions whether the conclusions of simple mathematical models of biological systems are trustworthy. The simplification of a specific model of calcium oscillations in hepatocytes is examined in detail, and the conclusions drawn from this scrutiny generalized. We formalize our choice of simplification approach through the use of functional 'building blocks'. A collection of models is constructed, each a progressively more simplified version of a well-understood model. The limiting model is a piecewise linear model that can be solved analytically. We find that, as expected, in many cases the simpler models produce incorrect results. However, when we make a sensitivity analysis, examining which aspects of the behaviour of the system are controlled by which parameters, the conclusions of the simple model often agree with those of the richer model. The hypothesis that the simplified model retains no information about the real sensitivities of the unsimplified model can be very strongly ruled out by treating the simplification process as a pseudo-random perturbation on the true sensitivity data. We conclude that sensitivity analysis is, therefore, of great importance to the analysis of simple mathematical models in biology. Our comparisons reveal which results of the sensitivity analysis regarding calcium oscillations in hepatocytes are robust to the simplifications necessarily involved in mathematical modelling. For example, we find that if a treatment is observed to strongly decrease the period of the oscillations while increasing the proportion of the cycle during which cellular calcium concentrations are rising, without affecting the inter-spike or maximum calcium concentrations, then it is likely that the treatment is acting on the plasma membrane calcium pump.

Some new speculative ideas about the “behavioral homeostasis theory” as to how the simple learned behaviors of habituation and sensitization improve organism survival throughout phylogeny

PubMed Central

Eisenstein, Edward M.; Eisenstein, Doris L.; Sarma, Jonnalagedda Sarma M.; Knapp, Herschel; Smith, James C.

2012-01-01

This paper explores further the “behavioral homeostasis theory” (BHT) regarding the evolutionary significance for organism survival of the two simple non-associative rapidly learned behaviors of habituation and sensitization. The BHT postulates that the evolutionary function of habituation and sensitization throughout phylogeny is to rapidly maximize an organism’s overall readiness to cope with new stimuli and to minimize unnecessary energy expenditure. These behaviors have survived with remarkable similarity throughout phylogeny from aneural protozoa to humans. The concept of “behavioral homeostasis” emphasizes that the homeostatic process is more than just maintaining internal equilibrium in the face of changing internal and external conditions. It emphasizes the rapid internal and external effector system changes that occur to optimize organism readiness to cope with any new external stimulus situation. Truly life-threatening stimuli elicit instinctive behavior such as fight, flee, or hide. If the stimulus is not life-threatening, the organism rapidly learns to adjust to an appropriate level of overall responsiveness over stimulus repetitions. The rapid asymptotic level approached by those who decrease their overall responsiveness to the second stimulus (habituaters) and those who increase their overall responsiveness to an identical second stimulus (sensitizers) not only optimizes readiness to cope with any new stimulus situation but also reduces unnecessary energy expenditure. This paper is based on a retrospective analysis of data from 4 effector system responses to eight repetitive tone stimuli in adult human males. The effector systems include the galvanic skin response, finger pulse volume, muscle frontalis and heart rate. The new information provides the basis for further exploration of the BHT including new predictions and proposed relatively simple experiments to test them. PMID:22896782

A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy

PubMed Central

Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

2016-01-01

Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion. PMID:27025266

Detection of adenosine triphosphate through polymerization-induced aggregation of actin-conjugated gold/silver nanorods.

PubMed

Liao, Yu-Ju; Shiang, Yen-Chun; Chen, Li-Yi; Hsu, Chia-Lun; Huang, Chih-Ching; Chang, Huan-Tsung

2013-11-08

We have developed a simple and selective nanosensor for the optical detection of adenosine triphosphate (ATP) using globular actin-conjugated gold/silver nanorods (G-actin-Au/Ag NRs). By simply mixing G-actin and Au/Ag NRs (length ~56 nm and diameter ~12 nm), G-actin-Au/Ag NRs were prepared which were stable in physiological solutions (25 mM Tris-HCl, 150 mM NaCl, 5.0 mM KCl, 3.0 mM MgCl2 and 1.0 mM CaCl2; pH 7.4). Introduction of ATP into the G-actin-Au/Ag NR solutions in the presence of excess G-actin induced the formation of filamentous actin-conjugated Au/Ag NR aggregates through ATP-induced polymerization of G-actin. When compared to G-actin-modified spherical Au nanoparticles having a size of 13 nm or 56 nm, G-actin-Au/Ag NRs provided better sensitivity for ATP, mainly because the longitudinal surface plasmon absorbance of the Au/Ag NR has a more sensitive response to aggregation. This G-actin-Au/Ag NR probe provided high sensitivity (limit of detection 25 nM) for ATP with remarkable selectivity (>10-fold) over other adenine nucleotides (adenosine, adenosine monophosphate and adenosine diphosphate) and nucleoside triphosphates (guanosine triphosphate, cytidine triphosphate and uridine triphosphate). It also allowed the determination of ATP concentrations in plasma samples without conducting tedious sample pretreatments; the only necessary step was simple dilution. Our experimental results are in good agreement with those obtained from a commercial luciferin-luciferase bioluminescence assay. Our simple, sensitive and selective approach appears to have a practical potential for the clinical diagnosis of diseases (e.g. cystic fibrosis) associated with changes in ATP concentrations.

A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy.

PubMed

Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

2016-03-30

Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion.

Detection of adenosine triphosphate through polymerization-induced aggregation of actin-conjugated gold/silver nanorods

NASA Astrophysics Data System (ADS)

Liao, Yu-Ju; Shiang, Yen-Chun; Chen, Li-Yi; Hsu, Chia-Lun; Huang, Chih-Ching; Chang, Huan-Tsung

2013-11-01

We have developed a simple and selective nanosensor for the optical detection of adenosine triphosphate (ATP) using globular actin-conjugated gold/silver nanorods (G-actin-Au/Ag NRs). By simply mixing G-actin and Au/Ag NRs (length ˜56 nm and diameter ˜12 nm), G-actin-Au/Ag NRs were prepared which were stable in physiological solutions (25 mM Tris-HCl, 150 mM NaCl, 5.0 mM KCl, 3.0 mM MgCl2 and 1.0 mM CaCl2; pH 7.4). Introduction of ATP into the G-actin-Au/Ag NR solutions in the presence of excess G-actin induced the formation of filamentous actin-conjugated Au/Ag NR aggregates through ATP-induced polymerization of G-actin. When compared to G-actin-modified spherical Au nanoparticles having a size of 13 nm or 56 nm, G-actin-Au/Ag NRs provided better sensitivity for ATP, mainly because the longitudinal surface plasmon absorbance of the Au/Ag NR has a more sensitive response to aggregation. This G-actin-Au/Ag NR probe provided high sensitivity (limit of detection 25 nM) for ATP with remarkable selectivity (>10-fold) over other adenine nucleotides (adenosine, adenosine monophosphate and adenosine diphosphate) and nucleoside triphosphates (guanosine triphosphate, cytidine triphosphate and uridine triphosphate). It also allowed the determination of ATP concentrations in plasma samples without conducting tedious sample pretreatments; the only necessary step was simple dilution. Our experimental results are in good agreement with those obtained from a commercial luciferin-luciferase bioluminescence assay. Our simple, sensitive and selective approach appears to have a practical potential for the clinical diagnosis of diseases (e.g. cystic fibrosis) associated with changes in ATP concentrations.

New agents with antimycobacterial activity.

PubMed

Marco-Contelles, José; Gómez-Sánchez, Elena

2005-11-01

In this paper, we report that a series of structurally simple a-halogenoacetamides show potent and excellent antimycobacterial activities against drug-sensitive Mycobacterium tuberculosis H(37)Rv and drug-resistant M. avium.

A simple and sensitive determination of histamine and N tau-methylhistamine in biological fluids by high-performance liquid chromatography with electrochemical detection.

PubMed

Houdi, A A; Crooks, P A; Van Loon, G R; Schubert, C A

1987-05-01

The determination of picomolar levels of histamine and its major metabolite, N tau-methylhistamine, in biological fluids was achieved using reversed-phase liquid chromatography coupled with electrochemical detection. A simple sample purification procedure for blood and urine samples was carried out prior to analysis using an Amberlite CG-50 cation-exchange resin, which afforded an excellent recovery of both compounds.

Biochemical analysis of force-sensitive responses using a large-scale cell stretch device.

PubMed

Renner, Derrick J; Ewald, Makena L; Kim, Timothy; Yamada, Soichiro

2017-09-03

Physical force has emerged as a key regulator of tissue homeostasis, and plays an important role in embryogenesis, tissue regeneration, and disease progression. Currently, the details of protein interactions under elevated physical stress are largely missing, therefore, preventing the fundamental, molecular understanding of mechano-transduction. This is in part due to the difficulty isolating large quantities of cell lysates exposed to force-bearing conditions for biochemical analysis. We designed a simple, easy-to-fabricate, large-scale cell stretch device for the analysis of force-sensitive cell responses. Using proximal biotinylation (BioID) analysis or phospho-specific antibodies, we detected force-sensitive biochemical changes in cells exposed to prolonged cyclic substrate stretch. For example, using promiscuous biotin ligase BirA* tagged α-catenin, the biotinylation of myosin IIA increased with stretch, suggesting the close proximity of myosin IIA to α-catenin under a force bearing condition. Furthermore, using phospho-specific antibodies, Akt phosphorylation was reduced upon stretch while Src phosphorylation was unchanged. Interestingly, phosphorylation of GSK3β, a downstream effector of Akt pathway, was also reduced with stretch, while the phosphorylation of other Akt effectors was unchanged. These data suggest that the Akt-GSK3β pathway is force-sensitive. This simple cell stretch device enables biochemical analysis of force-sensitive responses and has potential to uncover molecules underlying mechano-transduction.

Triglyceride glucose index as a surrogate measure of insulin sensitivity in obese adolescents with normoglycemia, prediabetes, and type 2 diabetes mellitus: Comparison with the hyperinsulinemic–euglycemic clamp

USDA-ARS?s Scientific Manuscript database

There is a need for simple surrogate estimates of insulin sensitivity in epidemiological studies of obese youth because the hyperinsulinemic-euglycemic clamp is not feasible on a large scale. Objectives: (i) To examine the triglyceride glucose (TyG) index (Ln[fasting triglycerides (mg/dL)'×'fasting ...

Quantum locking of mirrors in interferometers.

PubMed

Courty, Jean-Michel; Heidmann, Antoine; Pinard, Michel

2003-02-28

We show that quantum noise in very sensitive interferometric measurements such as gravitational-wave detectors can be drastically modified by quantum feedback. We present a new scheme based on active control to lock the motion of a mirror to a reference mirror at the quantum level. This simple technique allows one to reduce quantum effects of radiation pressure and to greatly enhance the sensitivity of the detection.

CB-EMIS CELL PHONE CLIENT

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

Lurie, Gordon

2007-01-02

The cell phone software allows any Java enabled cell phone to view sensor and meteorological data via an internet connection using a secure connection to the CB-EMIS Web Service. Users with appropriate privileges can monitor the state of the sensors and perform simple maintenance tasks remotely. All sensitive data is downloaded from the web service, thus protecting sensitive data in the event a cell phone is lost.

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

PubMed

Zilio, S C

2012-01-16

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

Cross-cultural differences in meter perception.

PubMed

Kalender, Beste; Trehub, Sandra E; Schellenberg, E Glenn

2013-03-01

We examined the influence of incidental exposure to varied metrical patterns from different musical cultures on the perception of complex metrical structures from an unfamiliar musical culture. Adults who were familiar with Western music only (i.e., simple meters) and those who also had limited familiarity with non-Western music were tested on their perception of metrical organization in unfamiliar (Turkish) music with simple and complex meters. Adults who were familiar with Western music detected meter-violating changes in Turkish music with simple meter but not in Turkish music with complex meter. Adults with some exposure to non-Western music that was unmetered or metrically complex detected meter-violating changes in Turkish music with both simple and complex meters, but they performed better on patterns with a simple meter. The implication is that familiarity with varied metrical structures, including those with a non-isochronous tactus, enhances sensitivity to the metrical organization of unfamiliar music.

To probe the equivalence and opulence of nanocrystal and nanotube based dye-sensitized solar cells

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

Jyoti, Divya, E-mail: divyabathla17@gmail.com; Mohan, Devendra

2016-05-06

Dye-Sensitized solar cells based on TiO{sub 2} nanocrystal and TiO{sub 2} nanotubes have been fabricated by a simple sol-gel hydrothermal process and their performances have been compared. Current density and voltage (JV) characteristics and incident photon to current conversion efficiency (IPCE) plots have been set as criterion to check which one is better as a photoanode candidate in dye-sensitized solar cell. It has been observed that although open circuit voltage values for both type of cells do not differ much still, nanotube based dye-sensitized solar cells are more successful having an efficiency value of 7.28%.

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

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

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

1986-03-01

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

New investigations of technical rhodium and iridium catalysts in homogeneous phase employing para-hydrogen induced polarization.

PubMed

Gutmann, Torsten; Ratajczyk, Tomasz; Dillenberger, Sonja; Xu, Yeping; Grünberg, Anna; Breitzke, Hergen; Bommerich, Ute; Trantzschel, Thomas; Bernarding, Johannes; Buntkowsky, Gerd

2011-09-01

It is shown that the para-hydrogen induced polarization (PHIP) phenomenon in homogenous solution containing the substrate styrene is also observable employing simple inorganic systems of the form MCl(3)·xH(2)O (M=Rh, Ir) as catalyst. Such observation confirms that already very simple metal complexes enable the creation of PHIP signal enhancement in solution. This opens up new pathways to increase the sensitivity of NMR and MRT by PHIP enhancement using cost-effective catalysts and will be essential for further mechanistic studies of simple transition metal systems. Copyright © 2011 Elsevier Inc. All rights reserved.

When alcohol is the answer: trapping, identifying and quantifying simple alkylating species in aqueous environments

PubMed Central

Penketh, P. G.; Shyam, K.; Baumann, R. P; Zhu, Rui; Ishiguro, K.; Sartorelli, A. C.; Ratner, E. S.

2016-01-01

Alkylating agents are a significant class of environmental carcinogens as well as commonly used anticancer therapeutics. Traditional alkylating activity assays have utilized the colorimetric reagent 4-(4-nitrobenzyl)pyridine (4NBP). However, 4NBP based assays have a relatively low sensitivity towards harder, more oxophilic alkylating species and are not well suited for the identification of the trapped alkyl moiety due to adduct instability. Herein we describe a method using water as the trapping agent which permits the trapping of simple alkylating electrophiles with a comparatively wide range of softness/hardness and permits the identification of donated simple alkyl moieties. PMID:27188264

High-accuracy self-mixing interferometer based on multiple reflections using a simple external reflecting mirror

NASA Astrophysics Data System (ADS)

Wang, Xiu-lin; Wei, Zheng; Wang, Rui; Huang, Wen-cai

2018-05-01

A self-mixing interferometer (SMI) with resolution twenty times higher than that of a conventional interferometer is developed by multiple reflections. Only by employing a simple external reflecting mirror, the multiple-pass optical configuration can be constructed. The advantage of the configuration is simple and easy to make the light re-injected back into the laser cavity. Theoretical analysis shows that the resolution of measurement is scalable by adjusting the number of reflections. The experiment shows that the proposed method has the optical resolution of approximate λ/40. The influence of displacement sensitivity gain ( G) is further analyzed and discussed in practical experiments.

Thermal and chemical treatment of polymer optical fiber Bragg grating sensors for enhanced mechanical sensitivity

NASA Astrophysics Data System (ADS)

Pospori, A.; Marques, C. A. F.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.

2017-07-01

An investigation of the thermal annealing effects on the strain, stress, and force sensitivities of polymer optical fiber Bragg grating sensors is performed. We demonstrate for the first time that the fiber annealing can enhance both stress and force sensitivities of Bragg grating sensors, with the possible cause being the molecular relaxation of the polymer when fiber is raised above the β -transition temperature. A simple, cost-effective, but well controlled method for fiber annealing is also presented in this work. In addition, the effects of chemical etching on the strain, stress, and force sensitivities have been investigated. Results show that fiber etching too can increase the force sensitivity, and it can also affect the strain and stress sensitivities of the Bragg grating sensors.

Angle-resolved diffraction grating biosensor based on porous silicon

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

Lv, Changwu; Li, Peng; Jia, Zhenhong, E-mail: jzhh@xju.edu.cn

2016-03-07

In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensormore » was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.« less

Effective moisture penetration depth model for residential buildings: Sensitivity analysis and guidance on model inputs

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

Woods, Jason; Winkler, Jon

Moisture buffering of building materials has a significant impact on the building's indoor humidity, and building energy simulations need to model this buffering to accurately predict the humidity. Researchers requiring a simple moisture-buffering approach typically rely on the effective-capacitance model, which has been shown to be a poor predictor of actual indoor humidity. This paper describes an alternative two-layer effective moisture penetration depth (EMPD) model and its inputs. While this model has been used previously, there is a need to understand the sensitivity of this model to uncertain inputs. In this paper, we use the moisture-adsorbent materials exposed to themore » interior air: drywall, wood, and carpet. We use a global sensitivity analysis to determine which inputs are most influential and how the model's prediction capability degrades due to uncertainty in these inputs. We then compare the model's humidity prediction with measured data from five houses, which shows that this model, and a set of simple inputs, can give reasonable prediction of the indoor humidity.« less

Effective moisture penetration depth model for residential buildings: Sensitivity analysis and guidance on model inputs

DOE PAGES

Woods, Jason; Winkler, Jon

2018-01-31

Moisture buffering of building materials has a significant impact on the building's indoor humidity, and building energy simulations need to model this buffering to accurately predict the humidity. Researchers requiring a simple moisture-buffering approach typically rely on the effective-capacitance model, which has been shown to be a poor predictor of actual indoor humidity. This paper describes an alternative two-layer effective moisture penetration depth (EMPD) model and its inputs. While this model has been used previously, there is a need to understand the sensitivity of this model to uncertain inputs. In this paper, we use the moisture-adsorbent materials exposed to themore » interior air: drywall, wood, and carpet. We use a global sensitivity analysis to determine which inputs are most influential and how the model's prediction capability degrades due to uncertainty in these inputs. We then compare the model's humidity prediction with measured data from five houses, which shows that this model, and a set of simple inputs, can give reasonable prediction of the indoor humidity.« less

Improving the performance of extreme learning machine for hyperspectral image classification

NASA Astrophysics Data System (ADS)

Li, Jiaojiao; Du, Qian; Li, Wei; Li, Yunsong

2015-05-01

Extreme learning machine (ELM) and kernel ELM (KELM) can offer comparable performance as the standard powerful classifier―support vector machine (SVM), but with much lower computational cost due to extremely simple training step. However, their performance may be sensitive to several parameters, such as the number of hidden neurons. An empirical linear relationship between the number of training samples and the number of hidden neurons is proposed. Such a relationship can be easily estimated with two small training sets and extended to large training sets so as to greatly reduce computational cost. Other parameters, such as the steepness parameter in the sigmodal activation function and regularization parameter in the KELM, are also investigated. The experimental results show that classification performance is sensitive to these parameters; fortunately, simple selections will result in suboptimal performance.

Highly selective and sensitive determination of Cu2+ in drink and water samples based on a 1,8-diaminonaphthalene derived fluorescent sensor

NASA Astrophysics Data System (ADS)

Sun, Tao; Li, Yang; Niu, Qingfen; Li, Tianduo; Liu, Yan

2018-04-01

A new simple and efficient fluorescent sensor L based on 1,8-diaminonaphthalene Schiff-base for highly sensitive and selective determination of Cu2+ in drink and water has been developed. This Cu2+-selective detection over other tested metal ions displayed an obvious color change from blue to colorless easily detected by naked eye. The detection limit is determined to be as low as 13.2 nM and the response time is very fast within 30 s. The 1:1 binding mechanism was well confirmed by fluorescence measurements, IR analysis and DFT calculations. Importantly, this sensor L was employed for quick detection of Cu2+ in drink and environmental water samples with satisfactory results, providing a simple, rapid, reliable and feasible Cu2+-sensing method.

A SENSITIVE METHOD FOR THE DETERMINATION OF CARBOXYHAEMOGLOBIN IN A FINGER PRICK SAMPLE OF BLOOD

PubMed Central

Commins, B. T.; Lawther, P. J.

1965-01-01

About 0·01 ml. of blood taken from a finger prick is dissolved in 10 ml. of 0·04% ammonia solution. The solution is divided into two halves, and oxygen is bubbled through one half to convert any carboxyhaemoglobin into oxyhaemoglobin. The spectra of the two halves are then compared in a spectrophotometer, and the difference between them is used to estimate the carboxyhaemoglobin content of the blood either graphically or by calculation from a simple formula. Calibration is simple and need only be done once. A sample of blood can be analysed in about 20 minutes, which includes the time to collect the sample. The method is sensitive enough to be used for the analysis of solutions of blood containing less than 1% carboxyhaemoglobin. PMID:14278801

The Inversion Effect for Chinese Characters is Modulated by Radical Organization.

PubMed

Luo, Canhuang; Chen, Wei; Zhang, Ye

2017-06-01

In studies of visual object recognition, strong inversion effects accompany the acquisition of expertise and imply the involvement of configural processing. Chinese literacy results in sensitivity to the orthography of Chinese characters. While there is some evidence that this orthographic sensitivity results in an inversion effect, and thus involves configural processing, that processing might depend on exact orthographic properties. Chinese character recognition is believed to involve a hierarchical process, involving at least two lower levels of representation: strokes and radicals. Radicals are grouped into characters according to certain types of structure, i.e. left-right structure, top-bottom structure, or simple characters with only one radical by itself. These types of radical structures vary in both familiarity, and in hierarchical level (compound versus simple characters). In this study, we investigate whether the hierarchical-level or familiarity of radical-structure has an impact on the magnitude of the inversion effect. Participants were asked to do a matching task on pairs of either upright or inverted characters with all the types of structure. Inversion effects were measured based on both reaction time and response sensitivity. While an inversion effect was observed in all 3 conditions, the magnitude of the inversion effect varied with radical structure, being significantly larger for the most familiar type of structure: characters consisting of 2 radicals organized from left to right. These findings indicate that character recognition involves extraction of configural structure as well as radical processing which play different roles in the processing of compound characters and simple characters.

Induced sensitivity of Bacillus subtilis colony morphology to mechanical media compression

PubMed Central

Polka, Jessica K.

2014-01-01

Bacteria from several taxa, including Kurthia zopfii, Myxococcus xanthus, and Bacillus mycoides, have been reported to align growth of their colonies to small features on the surface of solid media, including anisotropies created by compression. While the function of this phenomenon is unclear, it may help organisms navigate on solid phases, such as soil. The origin of this behavior is also unknown: it may be biological (that is, dependent on components that sense the environment and regulate growth accordingly) or merely physical. Here we show that B. subtilis, an organism that typically does not respond to media compression, can be induced to do so with two simple and synergistic perturbations: a mutation that maintains cells in the swarming (chained) state, and the addition of EDTA to the growth media, which further increases chain length. EDTA apparently increases chain length by inducing defects in cell separation, as the treatment has only marginal effects on the length of individual cells. These results lead us to three conclusions. First, the wealth of genetic tools available to B. subtilis will provide a new, tractable chassis for engineering compression sensitive organisms. Second, the sensitivity of colony morphology to media compression in Bacillus can be modulated by altering a simple physical property of rod-shaped cells. And third, colony morphology under compression holds promise as a rapid, simple, and low-cost way to screen for changes in the length of rod-shaped cells or chains thereof. PMID:25289183

ELISA-LOC: lab-on-a-chip for enzyme-linked immunodetection.

PubMed

Sun, Steven; Yang, Minghui; Kostov, Yordan; Rasooly, Avraham

2010-08-21

A miniature 96 sample ELISA-lab-on-a-chip (ELISA-LOC) was designed, fabricated, and tested for immunological detection of Staphylococcal Enterotoxin B (SEB). The chip integrates a simple microfluidics system into a miniature ninety-six sample plate, allowing the user to carry out an immunological assay without a laboratory. Assay reagents are delivered into the assay plate without the need for separate devices commonly used in immunoassays. The ELISA-LOC was constructed using Laminated Object Manufacturing (LOM) technology to assemble six layers with an acrylic (poly(methyl methacrylate) (PMMA)) core and five polycarbonate layers micromachined by a CO(2) laser. The ELISA-LOC has three main functional elements: reagent loading fluidics, assay and detection wells, and reagent removal fluidics, a simple "surface tension" valve used to control the flow. To enhance assay sensitivity and to perform the assay without a lab, ELISA-LOC detection combines several biosensing elements: (1) carbon nanotube (CNT) technology to enhance primary antibody immobilization, (2) sensitive ECL (electrochemiluminescence) detection, and (3) a charge-coupled device (CCD) detector for measuring the light signal generated by ECL. Using a sandwich ELISA assay, the system detected SEB at concentrations as low as 0.1 ng ml(-1), which is similar to the reported sensitivity of conventional ELISA. The fluidics system can be operated by a syringe and does not require power for operation. This simple point-of-care (POC) system is useful for carrying out various immunological assays and other complex medical assays without a laboratory.

The Physiology, Biochemistry and Genetics of Survival of Bacteria Subjected to Environmental Stress

DTIC Science & Technology

1981-11-01

sodium lauryl sulfate , but not to sodtimnl chloride or streptomycin alone. This sensitivity was again transient and capable of... sodium lauryl sulfate but not to sodium chloride or streptomycin alone. This sensitivity was again transient and capable of repair in the name simple...polymyxin B, bacitracin, and sodium lauryl . - 19 sutfate during growth, to ethylenediaminetetraacetic acid and sodium lauryl AUTHOR: 20 sulfate in

Flexible Dye-Sensitized Solar Cell Based on Vertical ZnO Nanowire Arrays

PubMed Central

2011-01-01

Flexible dye-sensitized solar cells are fabricated using vertically aligned ZnO nanowire arrays that are transferred onto ITO-coated poly(ethylene terephthalate) substrates using a simple peel-off process. The solar cells demonstrate an energy conversion efficiency of 0.44% with good bending tolerance. This technique paves a new route for building large-scale cost-effective flexible photovoltaic and optoelectronic devices. PMID:27502660

Sensitivity analysis of bi-layered ceramic dental restorations.

PubMed

Zhang, Zhongpu; Zhou, Shiwei; Li, Qing; Li, Wei; Swain, Michael V

2012-02-01

The reliability and longevity of ceramic prostheses have become a major concern. The existing studies have focused on some critical issues from clinical perspectives, but more researches are needed to address fundamental sciences and fabrication issues to ensure the longevity and durability of ceramic prostheses. The aim of this paper was to explore how "sensitive" the thermal and mechanical responses, in terms of changes in temperature and thermal residual stress of the bi-layered ceramic systems and crown models will be with respect to the perturbation of the design variables chosen (e.g. layer thickness and heat transfer coefficient) in a quantitative way. In this study, three bi-layered ceramic models with different geometries are considered: (i) a simple bi-layered plate, (ii) a simple bi-layer triangle, and (iii) an axisymmetric bi-layered crown. The layer thickness and convective heat transfer coefficient (or cooling rate) seem to be more sensitive for the porcelain fused on zirconia substrate models. The resultant sensitivities indicate a critical importance of the heat transfer coefficient and thickness ratio of core to veneer on the temperature distributions and residual stresses in each model. The findings provide a quantitative basis for assessing the effects of fabrication uncertainties and optimizing the design of ceramic prostheses. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Humidity-Responsive Gold Aerogel for Real-Time Monitoring of Human Breath.

PubMed

Ali, Israt; Chen, Liming; Huang, Youju; Song, Liping; Lu, Xuefei; Liu, Baoqing; Zhang, Lei; Zhang, Jiawei; Hou, Linxi; Chen, Tao

2018-04-24

Humidity sensors have received considerable attention in recent years because of their significance and wide applications in agriculture, industries, goods stores, and medical fields. However, the conventional humidity sensors usually possessed a complex sensing mechanism and low sensitivity and required a time-consuming, labor-intensive process. The exploration for an ideal sensing material to amplify the sensitivity of humidity sensors is still a big challenge. Herein, we developed a simple, low-cost, and scalable fabrication strategy to construct a highly sensitive humidity sensor based on polymer/gold nanoparticle (AuNP) hybrid materials. The hybrid polymer/AuNP aerogel was prepared by a simple freeze-drying method. By taking advantage of the conductivity of AuNPs and high surface area of the highly porous structure, the hybrid poly- N-isopropylacrylamide (PNIPAm)/AuNP aerogel showed high sensitivity to water molecules. Interestingly, the hybrid PNIPAm/AuNP aerogel-based humidity sensor can be used to detect human breath in different states, such as normal breath, fast breath, and deep breath, or in different individuals such as persons with illness, persons who are smoking, and persons who are normal, which is promising in practical flexible wearable devices for human health monitoring. In addition, the humidity sensor can be used in whistle tune recognition.

Beauty and the beholder: the role of visual sensitivity in visual preference

PubMed Central

Spehar, Branka; Wong, Solomon; van de Klundert, Sarah; Lui, Jessie; Clifford, Colin W. G.; Taylor, Richard P.

2015-01-01

For centuries, the essence of aesthetic experience has remained one of the most intriguing mysteries for philosophers, artists, art historians and scientists alike. Recently, views emphasizing the link between aesthetics, perception and brain function have become increasingly prevalent (Ramachandran and Hirstein, 1999; Zeki, 1999; Livingstone, 2002; Ishizu and Zeki, 2013). The link between art and the fractal-like structure of natural images has also been highlighted (Spehar et al., 2003; Graham and Field, 2007; Graham and Redies, 2010). Motivated by these claims and our previous findings that humans display a consistent preference across various images with fractal-like statistics, here we explore the possibility that observers’ preference for visual patterns might be related to their sensitivity for such patterns. We measure sensitivity to simple visual patterns (sine-wave gratings varying in spatial frequency and random textures with varying scaling exponent) and find that they are highly correlated with visual preferences exhibited by the same observers. Although we do not attempt to offer a comprehensive neural model of aesthetic experience, we demonstrate a strong relationship between visual sensitivity and preference for simple visual patterns. Broadly speaking, our results support assertions that there is a close relationship between aesthetic experience and the sensory coding of natural stimuli. PMID:26441611

A novel immunochromatographic electrochemical biosensor for highly sensitive and selective detection of trichloropyridinol, a biomarker of exposure to chlorpyrifos.

PubMed

Wang, Limin; Lu, Donglai; Wang, Jun; Du, Dan; Zou, Zhexiang; Wang, Hua; Smith, Jordan N; Timchalk, Charles; Liu, Fengquan; Lin, Yuehe

2011-02-15

We present a novel portable immunochromatographic electrochemical biosensor (IEB) for simple, rapid, and sensitive biomonitoring of trichloropyridinol (TCP), a metabolite biomarker of exposure to organophosphorus insecticides. Our new approach takes the advantage of immunochromatographic test strip for a rapid competitive immunoreaction and a disposable screen-printed carbon electrode for a rapid and sensitive electrochemical analysis of captured HRP labeling. Several key experimental parameters (e.g. immunoreaction time, the amount of HRP labeled TCP, concentration of the substrate for electrochemical measurements, and the blocking agents for the nitrocellulose membrane) were optimized to achieve a high sensitivity, selectivity and stability. Under optimal conditions, the IEB has demonstrated a wide linear range (0.1-100 ng/ml) with a detection limit as low as 0.1 ng/ml TCP. Furthermore, the IEB has been successfully applied for biomonitoring of TCP in the rat plasma samples with in vivo exposure to organophosphorus insecticides like Chlorpyrifos-oxon (CPF-oxon). The IEB thus opens up new pathways for designing a simple, rapid, clinically accurate, and quantitative tool for TCP detection, as well as holds a great promise for in-field screening of metabolite biomarkers, e.g., TCP, for humans exposed to organophosphorus insecticides. Copyright © 2010 Elsevier B.V. All rights reserved.

Multiplex detection of microRNAs by combining molecular beacon probes with T7 exonuclease-assisted cyclic amplification reaction.

PubMed

Liu, Yacui; Zhang, Jiangyan; Tian, Jingxiao; Fan, Xiaofei; Geng, Hao; Cheng, Yongqiang

2017-01-01

A simple, highly sensitive, and specific assay was developed for the homogeneous and multiplex detection of microRNAs (miRNAs) by combining molecular beacon (MB) probes and T7 exonuclease-assisted cyclic amplification. An MB probe with five base pairs in the stem region without special modification can effectively prevent the digestion by T7 exonuclease. Only in the presence of target miRNA is the MB probe hybridized with the target miRNA, and then digested by T7 exonuclease in the 5' to 3' direction. At the same time, the target miRNA is released and subsequently initiates the nuclease-assisted cyclic digestion process, generating enhanced fluorescence signal significantly. The results show that the combination of T7 exonuclease-assisted cyclic amplification reaction and MB probe possesses higher sensitivity for miRNA detection. Moreover, multiplex detection of miRNAs was successfully achieved by designing two MB probes labeled with FAM and Cy3, respectively. As a result, the method opens a new pathway for the sensitive and multiplex detection of miRNAs as well as clinical diagnosis. Graphical Abstract A simple, highly sensitive, and specific assay was developed for the detection of microRNAs by combining molecular beacon probes with T7 exonuclease-assisted cyclic amplification reaction.

Searching for light dark matter with the SLAC millicharge experiment.

PubMed

Diamond, M; Schuster, P

2013-11-27

New sub-GeV gauge forces ("dark photons") that kinetically mix with the photon provide a promising scenario for MeV-GeV dark matter and are the subject of a program of searches at fixed-target and collider facilities around the world. In such models, dark photons produced in collisions may decay invisibly into dark-matter states, thereby evading current searches. We reexamine results of the SLAC mQ electron beam dump experiment designed to search for millicharged particles and find that it was strongly sensitive to any secondary beam of dark matter produced by electron-nucleus collisions in the target. The constraints are competitive for dark photon masses in the ~1-30 MeV range, covering part of the parameter space that can reconcile the apparent (g-2)(μ) anomaly. Simple adjustments to the original SLAC search for millicharges may extend sensitivity to cover a sizable portion of the remaining (g-2)(μ) anomaly-motivated region. The mQ sensitivity is therefore complementary to ongoing searches for visible decays of dark photons. Compared to existing direct-detection searches, mQ sensitivity to electron-dark-matter scattering cross sections is more than an order of magnitude better for a significant range of masses and couplings in simple models.

Relapses vs. reactions in multibacillary leprosy: proposal of new relapse criteria.

PubMed

Linder, Katharina; Zia, Mutaher; Kern, Winfried V; Pfau, Ruth K M; Wagner, Dirk

2008-03-01

To compare a new scoring system for multibacillary (MB) leprosy relapses, which combines time factor, risk factors and clinical presentation at relapse, to WHO criteria. Data were collected on all relapses diagnosed between 1998 and 2004 at the Marie-Adelaide-Centre in Karachi, Pakistan, including case histories, clinical manifestations, follow-up, bacterial indices, treatment and contacts. For the diagnosis of MB relapses a simple scoring system was developed and validated on a data-set of mouse foot pads (MFP)-confirmed relapses (Leprosy Reviews, 76, 2005, 241). Its sensitivity was further evaluated in the Karachi relapse cohort. The P-value was calculated with McNemar's test with continuity correction. The new scoring system that combines time factor, risk factors and clinical presentation at relapse had a higher sensitivity in MFP-confirmed relapses than the WHO-criteria (95%vs. 65%, P < 0.01). The sensitivity of the scoring system was also significantly higher than the WHO criteria in the 57 cases of MB-relapses diagnosed in Karachi (72%vs. 54%, P < 0.05). This new simple scoring system for diagnosing MB-relapses in leprosy should be further validated in a prospective study to confirm its superior sensitivity and to evaluate the specificity of these criteria by using MFP-confirmation for patients presenting with signs of activity after treatment.

An advanced dual labeled gold nanoparticles probe to detect Cryptosporidium parvum using rapid immuno-dot blot assay.

PubMed

Thiruppathiraja, Chinnasamy; Kamatchiammal, Senthilkumar; Adaikkappan, Periyakaruppan; Alagar, Muthukaruppan

2011-07-15

The zoonotic protozoan parasite Cryptosporidium parvum poses a significant risk to public health. Due to the low infectious dose of C. parvum, remarkably sensitive detection methods are required for water and food industries analysis. However PCR affirmed sensing method of the causative nucleic acid has numerous advantages, still criterion demands for simple techniques and expertise understanding to extinguish its routine use. In contrast, protein based immuno detecting techniques are simpler to perform by a commoner, but lack of sensitivity due to inadequate signal amplification. In this paper, we focused on the development of a mere sensitive immuno detection method by coupling anti-cyst antibody and alkaline phosphatase on gold nanoparticle for C. parvum is described. Outcome of the sensitivity in an immuno-dot blot assay detection is enhanced by 500 fold (using conventional method) and visually be able to detect up to 10 oocysts/mL with minimal processing period. Techniques reported in this paper substantiate the convenience of immuno-dot blot assay for the routine screening of C. parvum in water/environmental examines and most importantly, demonstrates the potential of a prototype development of simple and inexpensive diagnostic technique. Copyright © 2011 Elsevier B.V. All rights reserved.

Electrolyte-free Amperometric Immunosensor using a Dendritic Nanotip†

PubMed Central

Kim, Jong-Hoon; Hiraiwa, Morgan; Lee, Hyun-Boo; Lee, Kyong-Hoon; Cangelosi, Gerard A.; Chung, Jae-Hyun

2013-01-01

Electric detection using a nanocomponent may lead to platforms for rapid and simple biosensing. Sensors composed of nanotips or nanodots have been described for highly sensitive amperometry enabled by confined geometry. However, both fabrication and use of nanostructured sensors remain challenging. This paper describes a dendritic nanotip used as an amperometric biosensor for highly sensitive detection of target bacteria. A dendritic nanotip is structured by Si nanowires coated with single-walled carbon nanotubes (SWCNTs) for generation of a high electric field. For reliable measurement using the dendritic structure, Si nanowires were uniformly fabricated by ultraviolet (UV) lithography and etching. The dendritic structure effectively increased the electric current density near the terminal end of the nanotip according to numerical computation. The electrical characteristics of a dendritic nanotip with additional protein layers was studied by cyclic voltammetry and I–V measurement in deionized (DI) water. When the target bacteria dielectrophoretically captured onto a nanotip were bound with fluorescence antibodies, the electric current through DI water decreased. Measurement results were consistent with fluorescence- and electron microscopy. The sensitivity of the amperometry was 10 cfu/sample volume (103 cfu/mL), which was equivalent to the more laborious fluorescence measurement method. The simple configuration of a dendritic nanotip can potentially offer an electrolyte-free detection platform for sensitive and rapid biosensors. PMID:23585927

Electrolyte-free Amperometric Immunosensor using a Dendritic Nanotip.

PubMed

Kim, Jong-Hoon; Hiraiwa, Morgan; Lee, Hyun-Boo; Lee, Kyong-Hoon; Cangelosi, Gerard A; Chung, Jae-Hyun

2013-01-01

Electric detection using a nanocomponent may lead to platforms for rapid and simple biosensing. Sensors composed of nanotips or nanodots have been described for highly sensitive amperometry enabled by confined geometry. However, both fabrication and use of nanostructured sensors remain challenging. This paper describes a dendritic nanotip used as an amperometric biosensor for highly sensitive detection of target bacteria. A dendritic nanotip is structured by Si nanowires coated with single-walled carbon nanotubes (SWCNTs) for generation of a high electric field. For reliable measurement using the dendritic structure, Si nanowires were uniformly fabricated by ultraviolet (UV) lithography and etching. The dendritic structure effectively increased the electric current density near the terminal end of the nanotip according to numerical computation. The electrical characteristics of a dendritic nanotip with additional protein layers was studied by cyclic voltammetry and I-V measurement in deionized (DI) water. When the target bacteria dielectrophoretically captured onto a nanotip were bound with fluorescence antibodies, the electric current through DI water decreased. Measurement results were consistent with fluorescence- and electron microscopy. The sensitivity of the amperometry was 10 cfu/sample volume (10 3 cfu/mL), which was equivalent to the more laborious fluorescence measurement method. The simple configuration of a dendritic nanotip can potentially offer an electrolyte-free detection platform for sensitive and rapid biosensors.

Modified graphene oxide sensors for ultra-sensitive detection of nitrate ions in water.

PubMed

Ren, Wen; Mura, Stefania; Irudayaraj, Joseph M K

2015-10-01

Nitrate ions is a very common contaminant in drinking water and has a significant impact on the environment, necessitating routine monitoring. Due to its chemical and physical properties, it is hard to directly detect nitrate ions with high sensitivity in a simple and inexpensive manner. Herein with amino group modified graphene oxide (GO) as a sensing element, we show a direct and ultra-sensitive method to detect nitrate ions, at a lowest detected concentration of 5 nM in river water samples, much lower than the reported methods based on absorption spectroscopy. Furthermore, unlike the reported strategies based on absorption spectroscopy wherein the nitrate concentration is determined by monitoring an increase in aggregation of gold nanoparticles (GNPs), our method evaluates the concentration of nitrate ions based on reduction in aggregation of GNPs for monitoring in real samples. To improve sensitivity, several optimizations were performed, including the assessment of the amount of modified GO required, concentration of GNPs and incubation time. The detection methodology was characterized by zeta potential, TEM and SEM. Our results indicate that an enrichment of modified GO with nitrate ions contributed to excellent sensitivity and the entire detection procedure could be completed within 75 min with only 20 μl of sample. This simple and rapid methodology was applied to monitor nitrate ions in real samples with excellent sensitivity and minimum pretreatment. The proposed approach paves the way for a novel means to detect anions in real samples and highlights the potential of GO based detection strategy for water quality monitoring. Copyright © 2015 Elsevier B.V. All rights reserved.

Recognition unit-free and self-cleaning photoelectrochemical sensing platform on TiO2 nanotube photonic crystals for sensitive and selective detection of dopamine release from mouse brain.

PubMed

Xin, Yanmei; Li, Zhenzhen; Wu, Wenlong; Fu, Baihe; Wu, Hongjun; Zhang, Zhonghai

2017-01-15

For implementing sensitive and selective detection of biological molecules, the biosensors are been designed more and more complicated. The exploration of detection platform in a simple way without loss their sensitivity and selectivity is always a big challenge. Herein, a prototype of recognition biomolecule unit-free photoelectrochemical (PEC) sensing platform with self-cleaning activity is proposed with TiO 2 nanotube photonic crystal (TiO 2 NTPCs) materials as photoelectrode, and dopamine (DA) molecule as both sensitizer and target analyte. The unique adsorption between DA and TiO 2 NTPCs induces the formation of charge transfer complex, which not only expends the optical absorption of TiO 2 into visible light region, thus significantly boosts the PEC performance under illumination of visible light, but also implements the selective detection of DA on TiO 2 photoelectrode. This simple but efficient PEC analysis platform presents a low detection limit of 0.15nm for detection of DA, which allows to realize the sensitive and selective determination of DA release from the mouse brain for its practical application after coupled with a microdialysis probe. The DA functionalized TiO 2 NTPCs PEC sensing platform opens up a new PEC detection model, without using extra-biomolecule auxiliary, just with target molecule naturally adsorbed on the electrode for sensitive and selective detection, and paves a new avenue for biosensors design with minimalism idea. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of Sport Related Concussion on Clinically Measured Simple Reaction Time

PubMed Central

Eckner, James T.; Kutcher, Jeffrey S.; Broglio, Steven P.; Richardson, James K.

2013-01-01

Background Reaction time (RT) is a valuable component of the sport concussion assessment battery. RT is typically measured using computers running specialized software, which limits its applicability in some athletic settings and populations. To address this, we developed a simple clinical test of RT (RTclin) that involves grasping a falling measuring stick. Purpose To determine the effect of concussion on RTclin and its sensitivity and specificity for concussion. Materials and methods Concussed athletes (n=28) and non-concussed control teammates (n=28) completed RTclin assessments at baseline and within 48 hours of injury. Repeated measures ANOVA compared mean baseline and follow-up RTclin values between groups. Sensitivity and specificity were calculated over a range of reliable change confidence levels. Results RTclin differed significantly between groups (p < .001): there was significant prolongation from baseline to post-injury in the concussed group (p= .003), with a trend toward improvement in the control group (p = .058). Sensitivity and specificity were maximized when a critical change value of 0 ms was applied (i.e., any increase in RTclin from baseline was interpreted as abnormal), which corresponded to a sensitivity of 75%, specificity of 68%, and a 65% reliable change confidence level. Conclusions RTclin appears sensitive to the effects of concussion and distinguished concussed and non-concussed athletes with similar sensitivity and specificity to other commonly used concussion assessment tools. Given its simplicity, low cost, and minimal time requirement, RTclin should be considered a viable component of the sports medicine provider’s multifaceted concussion assessment battery. PMID:23314889

Spatial segregation of adaptation and predictive sensitization in retinal ganglion cells

PubMed Central

Kastner, David B.; Baccus, Stephen A.

2014-01-01

Sensory systems change their sensitivity based upon recent stimuli to adjust their response range to the range of inputs, and to predict future sensory input. Here we report the presence of retinal ganglion cells that have antagonistic plasticity, showing central adaptation and peripheral sensitization. Ganglion cell responses were captured by a spatiotemporal model with independently adapting excitatory and inhibitory subunits, and sensitization requires GABAergic inhibition. Using a simple theory of signal detection we show that the sensitizing surround conforms to an optimal inference model that continually updates the prior signal probability. This indicates that small receptive field regions have dual functionality—to adapt to the local range of signals, but sensitize based upon the probability of the presence of that signal. Within this framework, we show that sensitization predicts the location of a nearby object, revealing prediction as a new functional role for adapting inhibition in the nervous system. PMID:23932000

Adjoint-Based Sensitivity and Uncertainty Analysis for Density and Composition: A User’s Guide

DOE PAGES

Favorite, Jeffrey A.; Perko, Zoltan; Kiedrowski, Brian C.; ...

2017-03-01

The ability to perform sensitivity analyses using adjoint-based first-order sensitivity theory has existed for decades. This paper provides guidance on how adjoint sensitivity methods can be used to predict the effect of material density and composition uncertainties in critical experiments, including when these uncertain parameters are correlated or constrained. Two widely used Monte Carlo codes, MCNP6 (Ref. 2) and SCALE 6.2 (Ref. 3), are both capable of computing isotopic density sensitivities in continuous energy and angle. Additionally, Perkó et al. have shown how individual isotope density sensitivities, easily computed using adjoint methods, can be combined to compute constrained first-order sensitivitiesmore » that may be used in the uncertainty analysis. This paper provides details on how the codes are used to compute first-order sensitivities and how the sensitivities are used in an uncertainty analysis. Constrained first-order sensitivities are computed in a simple example problem.« less

On the origin of enhanced sensitivity in nanoscale FET-based biosensors

PubMed Central

Shoorideh, Kaveh; Chui, Chi On

2014-01-01

Electrostatic counter ion screening is a phenomenon that is detrimental to the sensitivity of charge detection in electrolytic environments, such as in field-effect transistor-based biosensors. Using simple analytical arguments, we show that electrostatic screening is weaker in the vicinity of concave curved surfaces, and stronger in the vicinity of convex surfaces. We use this insight to show, using numerical simulations, that the enhanced sensitivity observed in nanoscale biosensors is due to binding of biomolecules in concave corners where screening is reduced. We show that the traditional argument, that increased surface area-to-volume ratio for nanoscale sensors is responsible for their increased sensitivity, is incorrect. PMID:24706861

Objective test for food sensitivity in asthmatic children: increased bronchial reactivity after cola drinks.

PubMed Central

Wilson, N; Vickers, H; Taylor, G; silverman, M

1982-01-01

Ten asthmatic children with a history of cough and wheeze after drinking a cola drink performed histamine inhalation tests before and 30 minutes after a drink of Pepsi-Cola, soda water, and water on three separate study days. There was no significant change in baseline peak expiratory flow after any of the three drinks. Sensitivity to histamine was increased after the cola drink (p less than 0.005) but was not significantly different after soda water or water. The detection of change in sensitivity to histamine appears to be a simple and effective method of testing for food sensitivity in asthma. Images p1228-a PMID:6803911

Synthesis and characterization of Allium cepa L. as photosensitizer of dye-sensitized solar cell

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

Sutikno, E-mail: smadnasri@yahoo.com; Afrian, Noverdi; Supriadi,

The synthesis and characterization of Allium cepa L. used as natural pigment for natural dye sensitizer of solar cell has successfully done and anthocyanin is extracted. Anthocynin is color pigment of plant which has characteristic absorption spectrum of photon and excites electrons up to pigment molecules. As the anthocyanin absorbed light increases the excited electrons increase as well. The generated current also increases and it leads to the efficiency increase. The energy conversion efficiency of the cells sensitized with dye of Allium cepa L. was 3,045 x 10{sup −4}%. A simple technique was taken to fabricate dye sensitizer solar cellmore » is spincoating.« less

Single strand DNA functionalized single wall carbon nanotubes as sensitive electrochemical labels for arsenite detection.

PubMed

Wang, Yonghong; Wang, Ping; Wang, Yiqiang; He, Xiaoxiao; Wang, Kemin

2015-08-15

In this work, a simple and sensitive electrochemical strategy for arsenite detection based on the ability of arsenite bound to single-strand DNA (ssDNA) and the signal transduction of single wall carbon nanotubes (SWCNTs) is developed. To realize this purpose, the ssDNA/SWCNTs complexes were formed at first by making ssDNA wrapped around SWCNTs via π-stacking. In the presence of arsenite, the arsenite could strongly bind with the G/T bases of ssDNA and decrease the π-π interaction between ssDNA and SWCNTs, resulting in a certain amount of ssDNA dissociating from the complexes. The separated SWCNTs were selectively assembled on the self-assembled monolayer (SAM) modified Au electrode. Then the SWCNTs onto the SAM-modified Au electrode substantially restored heterogeneous electron transfer that was almost totally blocked by the SAM. The assembled SWCNTs could generate a considerably sensitive and specific tactic for signal transduction, which was related to the concentration of the arsenite. Through detecting the currents mediated by SWCNTs, a linear response to concentration of arsenite ranging from 0.5 to 10ppb and a detection limit of 0.5ppb was readily achieved with desirable specificity and sensitivity. Such a SWCNTs-based biosensor creates a simple, sensitive, nonradioactive route for detection of arsenite. In addition, this demonstration provides a new approach to fabrication of stable biosensors with favorable electrochemical properties believed to be appealing to electroanalytical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

A simple highly sensitive and selective aptamer-based colorimetric sensor for environmental toxins microcystin-LR in water samples.

PubMed

Li, Xiuyan; Cheng, Ruojie; Shi, Huijie; Tang, Bo; Xiao, Hanshuang; Zhao, Guohua

2016-03-05

A simple and highly sensitive aptamer-based colorimetric sensor was developed for selective detection of Microcystin-LR (MC-LR). The aptamer (ABA) was employed as recognition element which could bind MC-LR with high-affinity, while gold nanoparticles (AuNPs) worked as sensing materials whose plasma resonance absorption peaks red shifted upon binding of the targets at a high concentration of sodium chloride. With the addition of MC-LR, the random coil aptamer adsorbed on Au NPs altered into regulated structure to form MC-LR-aptamer complexes and broke away from the surface of Au NPs, leading to the aggregation of AuNPs, and the color converted from red to blue due to the interparticle plasmon coupling. Results showed that our aptamer-based colorimetric sensor exhibited rapid and sensitive detection performance for MC-LR with linear range from 0.5 nM to 7.5 μM and the detection limit reached 0.37 nM. Meanwhile, the pollutants usually coexisting with MC-LR in pollutant water samples had not demonstrated disturbance for detecting of MC-LR. The mechanism was also proposed suggesting that high affinity interaction between aptamer and MC-LR significantly enhanced the sensitivity and selectivity for MC-LR detection. Besides, the established method was utilized in analyzing real water samples and splendid sensitivity and selectivity were obtained as well. Copyright © 2015 Elsevier B.V. All rights reserved.

Developing Bayesian adaptive methods for estimating sensitivity thresholds (d′) in Yes-No and forced-choice tasks

PubMed Central

Lesmes, Luis A.; Lu, Zhong-Lin; Baek, Jongsoo; Tran, Nina; Dosher, Barbara A.; Albright, Thomas D.

2015-01-01

Motivated by Signal Detection Theory (SDT), we developed a family of novel adaptive methods that estimate the sensitivity threshold—the signal intensity corresponding to a pre-defined sensitivity level (d′ = 1)—in Yes-No (YN) and Forced-Choice (FC) detection tasks. Rather than focus stimulus sampling to estimate a single level of %Yes or %Correct, the current methods sample psychometric functions more broadly, to concurrently estimate sensitivity and decision factors, and thereby estimate thresholds that are independent of decision confounds. Developed for four tasks—(1) simple YN detection, (2) cued YN detection, which cues the observer's response state before each trial, (3) rated YN detection, which incorporates a Not Sure response, and (4) FC detection—the qYN and qFC methods yield sensitivity thresholds that are independent of the task's decision structure (YN or FC) and/or the observer's subjective response state. Results from simulation and psychophysics suggest that 25 trials (and sometimes less) are sufficient to estimate YN thresholds with reasonable precision (s.d. = 0.10–0.15 decimal log units), but more trials are needed for FC thresholds. When the same subjects were tested across tasks of simple, cued, rated, and FC detection, adaptive threshold estimates exhibited excellent agreement with the method of constant stimuli (MCS), and with each other. These YN adaptive methods deliver criterion-free thresholds that have previously been exclusive to FC methods. PMID:26300798

Phase sensitive diffraction sensor for high sensitivity refractive index measurement

NASA Astrophysics Data System (ADS)

Kumawat, Nityanand; Varma, Manoj; Kumar, Sunil

2018-02-01

In this study a diffraction based sensor has been developed for bio molecular sensing applications and performing assays in real time. A diffraction grating fabricated on a glass substrate produced diffraction patterns both in transmission and reflection when illuminated by a laser diode. We used zeroth order I(0,0) as reference and first order I(0,1) as signal channel and conducted ratiometric measurements that reduced noise by more than 50 times. The ratiometric approach resulted in a very simple instrumentation with very high sensitivity. In the past, we have shown refractive index measurements both for bulk and surface adsorption using the diffractive self-referencing approach. In the current work we extend the same concept to higher diffraction orders. We have considered order I(0,1) and I(1,1) and performed ratiometric measurements I(0,1)/I(1,1) to eliminate the common mode fluctuations. Since orders I(0,1) and I(1,1) behaved opposite to each other, the resulting ratio signal amplitude increased more than twice compared to our previous results. As a proof of concept we used different salt concentrations in DI water. Increased signal amplitude and improved fluid injection system resulted in more than 4 times improvement in detection limit, giving limit of detection 1.3×10-7 refractive index unit (RIU) compared to our previous results. The improved refractive index sensitivity will help significantly for high sensitivity label free bio sensing application in a very cost-effective and simple experimental set-up.

A simple and rapid latex fixation test for measuring immunoglobulins produced in cell cultures.

PubMed

Kasahara, T; Harada, H; Enomoto, H; Itoh, Y; Kawai, T; Shioiri-Nakano, K

1981-01-01

A rapid and simple latex fixation test (LFT), which quantifies immunoglobulin (Ig) released into culture supernatants is described. Latex particles are coated with rabbit anti-human IgG, IgA or IgM antibodies. With this LFT technique the concentration of Ig is determined within a few minutes. The LFT is as sensitive and quantitative as double-antibody radioimmunoassay and is capable of detecting 35, 68 and 225 ng/ml of IgG, IgA and IgM, respectively.

A Simple Method for High Throughput Chemical Screening in Caenorhabditis Elegans

PubMed Central

Lucanic, Mark; Garrett, Theo; Gill, Matthew S.; Lithgow, Gordon J.

2018-01-01

Caenorhabditis elegans is a useful organism for testing chemical effects on physiology. Whole organism small molecule screens offer significant advantages for identifying biologically active chemical structures that can modify complex phenotypes such as lifespan. Described here is a simple protocol for producing hundreds of 96-well culture plates with fairly consistent numbers of C. elegans in each well. Next, we specified how to use these cultures to screen thousands of chemicals for effects on the lifespan of the nematode C. elegans. This protocol makes use of temperature sensitive sterile strains, agar plate conditions, and simple animal handling to facilitate the rapid and high throughput production of synchronized animal cultures for screening. PMID:29630057

When alcohol is the answer: Trapping, identifying and quantifying simple alkylating species in aqueous environments.

PubMed

Penketh, Philip G; Shyam, Krishnamurthy; Baumann, Raymond P; Zhu, Rui; Ishiguro, Kimiko; Sartorelli, Alan C; Ratner, Elena S

2016-09-01

Alkylating agents are a significant class of environmental carcinogens as well as commonly used anticancer therapeutics. Traditional alkylating activity assays have utilized the colorimetric reagent 4-(4-nitrobenzyl)pyridine (4NBP). However, 4NBP based assays have a relatively low sensitivity towards harder, more oxophilic alkylating species and are not well suited for the identification of the trapped alkyl moiety due to adduct instability. Herein we describe a method using water as the trapping agent which permits the trapping of simple alkylating electrophiles with a comparatively wide range of softness/hardness and permits the identification of donated simple alkyl moieties. Copyright © 2016 Elsevier Inc. All rights reserved.

Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures

PubMed Central

Bogart, Justin A.; Cole, Bren E.; Boreen, Michael A.; Lippincott, Connor A.; Manor, Brian C.; Carroll, Patrick J.; Schelter, Eric J.

2016-01-01

Rare earth (RE) metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare REs. To incentivize recycling, there is a clear need for the development of simple methods for targeted separations of mixtures of RE metal salts. Metal complexes of a tripodal hydroxylaminato ligand, TriNOx3–, featured a size-sensitive aperture formed of its three η2-(N,O) ligand arms. Exposure of cations in the aperture induced a self-associative equilibrium comprising RE(TriNOx)THF and [RE(TriNOx)]2 species. Differences in the equilibrium constants Kdimer for early and late metals enabled simple separations through leaching. Separations were performed on RE1/RE2 mixtures, where RE1 = La–Sm and RE2 = Gd–Lu, with emphasis on Eu/Y separations for potential applications in the recycling of phosphor waste from compact fluorescent light bulbs. Using the leaching method, separations factors approaching 2,000 were obtained for early–late RE combinations. Following solvent optimization, >95% pure samples of Eu were obtained with a 67% recovery for the technologically relevant Eu/Y separation. PMID:27956636

A simple and rapid creatinine sensing via DLS selectivity, using calix[4]arene thiol functionalized gold nanoparticles.

PubMed

Sutariya, Pinkesh G; Pandya, Alok; Lodha, Anand; Menon, Shobhana K

2016-01-15

A new, simple, ultra-sensitive and selective approach has been reported for the "on spot" colorimetric detection of creatinine based on calix[4]arene functionalized gold nanoparticles (AuNPs) with excellent discrimination in the presence of other biomolecules. The lower detection limit of the method is 2.16nM. The gold nanoparticles and p-tert-butylcalix[4]arene were synthesized by microwave assisted method. Specifically, in our study, we used dynamic light scattering (DLS) which is a powerful method for the determination of small changes in particle size, improved selectivity and sensitivity of the creatinine detection system over colorimetric method. The nanoassembly is characterized by Transmission electron microscopy (TEM), DLS, UV-vis and ESI-MS spectroscopy, which demonstrates the binding affinity due its ability of hydrogen bonding and electrostatic interaction between -NH group of creatinine and pSDSC4. It exhibits fast response time (<60s) to creatinine and has long shelf-life (>5 weeks). The developed pSDSC4-AuNPs based creatinine biosensor will be established as simple, reliable and accurate tool for the determination of creatinine in human urine samples. Copyright © 2015 Elsevier B.V. All rights reserved.

In the Field Feasibility of a Simple Method to Check for Radioactivity in Commodities and in the Environment

PubMed Central

Alessandri, Stefano

2017-01-01

Introduction: Some release of radionuclides into the environment can be expected from the growing number of nuclear plants, either in or out of service. The citizen and the big organization could be both interested in simple and innovative methods for checking the radiological safety of their environment and of commodities, starting from foods. Methods: In this work three methods to detect radioactivity are briefly compared  focusing on the most recent, which converts a smartphone into a radiation counter. Results: The results of a simple sensitivity test are presented showing the measure of the activity of reference sources put at different distances from each sensor. Discussion: The three methods are discussed in terms of availability, technology, sensitivity, resolution and usefulness. The reported results can be usefully transferred into a radiological emergency scenario and they also offer some interesting implication for our current everyday life, but show that the hardware of the tested smart-phone can detect only high levels of radioactivity. However the technology could be interesting to build a working detection and measurement chain which could start from a diffused and networked first screening before the final high resolution analysis. PMID:28744409

Accomplishing simple, solubility-based separations of rare earth elements with complexes bearing size-sensitive molecular apertures.

PubMed

Bogart, Justin A; Cole, Bren E; Boreen, Michael A; Lippincott, Connor A; Manor, Brian C; Carroll, Patrick J; Schelter, Eric J

2016-12-27

Rare earth (RE) metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare REs. To incentivize recycling, there is a clear need for the development of simple methods for targeted separations of mixtures of RE metal salts. Metal complexes of a tripodal hydroxylaminato ligand, TriNOx 3- , featured a size-sensitive aperture formed of its three η 2 -(N,O) ligand arms. Exposure of cations in the aperture induced a self-associative equilibrium comprising RE(TriNOx)THF and [RE(TriNOx)] 2 species. Differences in the equilibrium constants K dimer for early and late metals enabled simple separations through leaching. Separations were performed on RE1/RE2 mixtures, where RE1 = La-Sm and RE2 = Gd-Lu, with emphasis on Eu/Y separations for potential applications in the recycling of phosphor waste from compact fluorescent light bulbs. Using the leaching method, separations factors approaching 2,000 were obtained for early-late RE combinations. Following solvent optimization, >95% pure samples of Eu were obtained with a 67% recovery for the technologically relevant Eu/Y separation.

Re-scan confocal microscopy: scanning twice for better resolution.

PubMed

De Luca, Giulia M R; Breedijk, Ronald M P; Brandt, Rick A J; Zeelenberg, Christiaan H C; de Jong, Babette E; Timmermans, Wendy; Azar, Leila Nahidi; Hoebe, Ron A; Stallinga, Sjoerd; Manders, Erik M M

2013-01-01

We present a new super-resolution technique, Re-scan Confocal Microscopy (RCM), based on standard confocal microscopy extended with an optical (re-scanning) unit that projects the image directly on a CCD-camera. This new microscope has improved lateral resolution and strongly improved sensitivity while maintaining the sectioning capability of a standard confocal microscope. This simple technology is typically useful for biological applications where the combination high-resolution and high-sensitivity is required.

Facile fabrication of networked patterns and their superior application to realize the virus immobilized networked pattern circuit.

PubMed

Choi, Kyung Min; Lee, Seok Jae; Choi, Jung Hoon; Park, Tae Jung; Park, Jong Wan; Shin, Weon Ho; Kang, Jeung Ku

2010-12-07

A facile route to fabricate a protein-immobilized network pattern circuit for rapid and highly sensitive diagnosis was developed via the evaporation directed impromptu patterning method and selective avian influenza virus (AIV) immobilization. The response to the 10 fg mL(-1) anti-AI antibody demonstrates that this easy and simple circuit has about 1000 times higher sensitivity compared to those of conventional approaches.

Simple Fabrication of a Highly Sensitive and Fast Glucose Biosensor using Enzyme Immobilized in Mesocellular Carbon Foam

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

Lee, Dohoon; Lee, Jinwoo; Kim, Jungbae

2005-12-05

We fabricated a highly sensitive and fast glucose biosensor by simply immobilizing glucose oxidase in mesocellular carbon foam. Due to its unique structure, the MSU-F-C enabled high enzyme loading without serious mass transfer limitation, resulting in high catalytic efficiency. As a result, the glucose biosensor fabricated with MSU-F-C/GOx showed a high sensitivity and fast response. Given these results and the inherent electrical conductivity, we anticipate that MSU-F-C will make a useful matrix for enzyme immobilization in various biocatalytic and electrobiocatalytic applications.

Refractive index sensor based on plastic optical fiber with tapered structure.

PubMed

De-Jun, Feng; Guan-Xiu, Liu; Xi-Lu, Liu; Ming-Shun, Jiang; Qing-Mei, Sui

2014-04-01

This work reports a refractive index sensor made of plastic optical fiber (POF) with tapered structure. Transmission loss is measured when the external environment's refractive index changes from 1.33 to 1.41. Three wavelengths (532, 633, and 780 nm) are used to evaluate the sensitivity of the sensor, and results indicate that 633 nm is the best sensing wavelength due to the increased levels of sensitivity achieved at this wavelength. A biconical sensing structure is designed to enhance the sensitivity of the sensor. A sensitivity of 950 μW/RIU at 633 nm is obtained for a biconical sensing structure when launched power is 1 mW. Due to its sensitivity to the refractive index and simple construction, POF with tapered structure has potential applications in the biosensing field.

Development and validation of a simple questionnaire for the identification of hereditary breast cancer in primary care

PubMed Central

2009-01-01

Background Breast cancer is a significant public health problem worldwide and the development of tools to identify individuals at-risk for hereditary breast cancer syndromes, where specific interventions can be proposed to reduce risk, has become increasingly relevant. A previous study in Southern Brazil has shown that a family history suggestive of these syndromes may be prevalent at the primary care level. Development of a simple and sensitive instrument, easily applicable in primary care units, would be particularly helpful in underserved communities in which identification and referral of high-risk individuals is difficult. Methods A simple 7-question instrument about family history of breast, ovarian and colorectal cancer, FHS-7, was developed to screen for individuals with an increased risk for hereditary breast cancer syndromes. FHS-7 was applied to 9218 women during routine visits to primary care units in Southern Brazil. Two consecutive samples of 885 women and 910 women who answered positively to at least one question and negatively to all questions were included, respectively. The sensitivity, specificity and positive and negative predictive values were determined. Results Of the 885 women reporting a positive family history, 211 (23.8%; CI95%: 21.5–26.2) had a pedigree suggestive of a hereditary breast and/or breast and colorectal cancer syndrome. Using as cut point one positive answer, the sensitivity and specificity of the instrument were 87.6% and 56.4%, respectively. Concordance between answers in two different applications was given by a intra-class correlation (ICC) of 0.84 for at least one positive answer. Temporal stability of the instrument was adequate (ICC = 0.65). Conclusion A simple instrument for the identification of the most common hereditary breast cancer syndrome phenotypes, showing good specificity and temporal stability was developed and could be used as a screening tool in primary care to refer at-risk individuals for genetic evaluations. PMID:19682358

Accuracy of simple urine tests for diagnosis of urinary tract infections in low-risk pregnant women.

PubMed

Feitosa, Danielle Cristina Alves; da Silva, Márcia Guimarães; de Lima Parada, Cristina Maria Garcia

2009-01-01

Anatomic and physiological alterations during pregnancy predispose pregnant women to urinary tract infections (UTI). This study aimed to identify the accuracy of the simple urine test for UTI diagnosis in low-risk pregnant women. Diagnostic test performance was conducted in Botucatu, SP, involving 230 pregnant women, between 2006 and 2008. Results showed 10% UTI prevalence. Sensitivity, specificity and accuracy of the simple urine test were 95.6%, 63.3% and 66.5%, respectively, in relation to UTI diagnoses. The analysis of positive (PPV) and negative (NPV) predictive values showed that, when a regular simple urine test was performed, the chance of UTI occurrence was small (NPV 99.2%). In view of an altered result for such a test, the possibility of UTI existence was small (PPV 22.4%). It was concluded that the accuracy of the simple urine test as a diagnostic means for UTI was low, and that performing a urine culture is essential for appropriate diagnosis.

Mini-Column Ion-Exchange Separation and Atomic Absorption Quantitation of Nickel, Cobalt, and Iron: An Undergraduate Quantitative Analysis Experiment.

ERIC Educational Resources Information Center

Anderson, James L.; And Others

1980-01-01

Presents an undergraduate quantitative analysis experiment, describing an atomic absorption quantitation scheme that is fast, sensitive and comparatively simple relative to other titration experiments. (CS)

Hydrogen-Detection Apparatus

NASA Technical Reports Server (NTRS)

Ross, H. Richard; Bourgeois, Chris M.

1995-01-01

Apparatus continuously monitors concentration of hydrogen, at level ranging from few parts per million to several percent, in mixture of gases. Simple and fast, providing high sensitivity and linear response. Used to alert technicians to potentially explosive concentrations of residual hydrogen.

Hearing light

NASA Astrophysics Data System (ADS)

Euler, Manfred; Niemann, Kurt; Müller, Andreas

2000-09-01

The sensitivity of the human ear is brought to a close by an amazingly simple experiment. The design of a photoacoustic converter with kitchen equipment, which helps to gain qualitative insights on ear performance as well as on photoacoustic detection methods, is described.

Spectrophotometric total reducing sugars assay based on cupric reduction.

PubMed

Başkan, Kevser Sözgen; Tütem, Esma; Akyüz, Esin; Özen, Seda; Apak, Reşat

2016-01-15

As the concentration of reducing sugars (RS) is controlled by European legislation for certain specific food and beverages, a simple and sensitive spectrophotometric method for the determination of RS in various food products is proposed. The method is based on the reduction of Cu(II) to Cu(I) with reducing sugars in alkaline medium in the presence of 2,9-dimethyl-1,10-phenanthroline (neocuproine: Nc), followed by the formation of a colored Cu(I)-Nc charge-transfer complex. All simple sugars tested had the linear regression equations with almost equal slope values. The proposed method was successfully applied to fresh apple juice, commercial fruit juices, milk, honey and onion juice. Interference effect of phenolic compounds in plant samples was eliminated by a solid phase extraction (SPE) clean-up process. The method was proven to have higher sensitivity and precision than the widely used dinitrosalicylic acid (DNS) colorimetric method. Copyright © 2015 Elsevier B.V. All rights reserved.

Linearization of the bradford protein assay.

PubMed

Ernst, Orna; Zor, Tsaffrir

2010-04-12

Determination of microgram quantities of protein in the Bradford Coomassie brilliant blue assay is accomplished by measurement of absorbance at 590 nm. This most common assay enables rapid and simple protein quantification in cell lysates, cellular fractions, or recombinant protein samples, for the purpose of normalization of biochemical measurements. However, an intrinsic nonlinearity compromises the sensitivity and accuracy of this method. It is shown that under standard assay conditions, the ratio of the absorbance measurements at 590 nm and 450 nm is strictly linear with protein concentration. This simple procedure increases the accuracy and improves the sensitivity of the assay about 10-fold, permitting quantification down to 50 ng of bovine serum albumin. Furthermore, the interference commonly introduced by detergents that are used to create the cell lysates is greatly reduced by the new protocol. A linear equation developed on the basis of mass action and Beer's law perfectly fits the experimental data.

Mobile phone-based syndromic surveillance system, Papua New Guinea.

PubMed

Rosewell, Alexander; Ropa, Berry; Randall, Heather; Dagina, Rosheila; Hurim, Samuel; Bieb, Sibauk; Datta, Siddhartha; Ramamurthy, Sundar; Mola, Glen; Zwi, Anthony B; Ray, Pradeep; MacIntyre, C Raina

2013-11-01

The health care system in Papua New Guinea is fragile, and surveillance systems infrequently meet international standards. To strengthen outbreak identification, health authorities piloted a mobile phone-based syndromic surveillance system and used established frameworks to evaluate whether the system was meeting objectives. Stakeholder experience was investigated by using standardized questionnaires and focus groups. Nine sites reported data that included 7 outbreaks and 92 cases of acute watery diarrhea. The new system was more timely (2.4 vs. 84 days), complete (70% vs. 40%), and sensitive (95% vs. 26%) than existing systems. The system was simple, stable, useful, and acceptable; however, feedback and subnational involvement were weak. A simple syndromic surveillance system implemented in a fragile state enabled more timely, complete, and sensitive data reporting for disease risk assessment. Feedback and provincial involvement require improvement. Use of mobile phone technology might improve the timeliness and efficiency of public health surveillance.

Mobile Phone–based Syndromic Surveillance System, Papua New Guinea

PubMed Central

Ropa, Berry; Randall, Heather; Dagina, Rosheila; Hurim, Samuel; Bieb, Sibauk; Datta, Siddhartha; Ramamurthy, Sundar; Mola, Glen; Zwi, Anthony B.; Ray, Pradeep; MacIntyre, C. Raina

2013-01-01

The health care system in Papua New Guinea is fragile, and surveillance systems infrequently meet international standards. To strengthen outbreak identification, health authorities piloted a mobile phone–based syndromic surveillance system and used established frameworks to evaluate whether the system was meeting objectives. Stakeholder experience was investigated by using standardized questionnaires and focus groups. Nine sites reported data that included 7 outbreaks and 92 cases of acute watery diarrhea. The new system was more timely (2.4 vs. 84 days), complete (70% vs. 40%), and sensitive (95% vs. 26%) than existing systems. The system was simple, stable, useful, and acceptable; however, feedback and subnational involvement were weak. A simple syndromic surveillance system implemented in a fragile state enabled more timely, complete, and sensitive data reporting for disease risk assessment. Feedback and provincial involvement require improvement. Use of mobile phone technology might improve the timeliness and efficiency of public health surveillance. PMID:24188144

Magnetic field sensor based on the magnetic-fluid-clad combined with singlemode-multimode-singlemode fiber and large core-offset splicing structure

NASA Astrophysics Data System (ADS)

Lv, Ri-qing; Qian, Jun-kai; Zhao, Yong

2018-03-01

A simple, compact optical fiber magnetic field sensor is proposed and experimentally demonstrated in this paper. It is based on the magnetic-fluid-clad combined with singlemode-multimode-singlemode fiber structure and large core-offset splicing structure. It was protected by a section of capillary tube and was sealed by UV glue. A sensing property study of the combined optical fiber structure and the proposed sensor were carried out. The experimental results show that the sensitivity of the refractive index of the optical fiber sensing structure is up to 156.63 nm/RIU and the magnetic field sensitivity of the proposed sensor is up to -97.24 pm/Oe in the range from 72.4 Oe to 297.8 Oe. The proposed sensor has several other advantages, such as simple structure, small size, easy fabrication and low cost.

A high-throughput colorimetric assay for glucose detection based on glucose oxidase-catalyzed enlargement of gold nanoparticles

NASA Astrophysics Data System (ADS)

Xiong, Yanmei; Zhang, Yuyan; Rong, Pengfei; Yang, Jie; Wang, Wei; Liu, Dingbin

2015-09-01

We developed a simple high-throughput colorimetric assay to detect glucose based on the glucose oxidase (GOx)-catalysed enlargement of gold nanoparticles (AuNPs). Compared with the currently available glucose kit method, the AuNP-based assay provides higher clinical sensitivity at lower cost, indicating its great potential to be a powerful tool for clinical screening of glucose.We developed a simple high-throughput colorimetric assay to detect glucose based on the glucose oxidase (GOx)-catalysed enlargement of gold nanoparticles (AuNPs). Compared with the currently available glucose kit method, the AuNP-based assay provides higher clinical sensitivity at lower cost, indicating its great potential to be a powerful tool for clinical screening of glucose. Electronic supplementary information (ESI) available: Experimental section and additional figures. See DOI: 10.1039/c5nr03758a

Simple and Sensitive Colorimetric Assay for Pb2+ Based on Glutathione Protected Ag Nanoparticles by Salt Amplification.

PubMed

Chen, Zhang; Li, Huidong; Chu, Lin; Liu, Chenbin; Luo, Shenglian

2015-02-01

A simple and sensitive colorimetric assay for Pb2+ detection has been reported using glutathione protected silver nanoparticles (AgNPs) by salt amplification. The naked AgNPs aggregate under the influence of salt. Glutathione (GSH) can bind to AgNPs via Ag-S bond, helping AgNPs to against salt-induced aggregation. However, GSH binding to AgNPs can be compromised by the interaction between Pb2+ and GSH. As a result, Pb2+-mediated aggregation of AgNPs under the influence of salt is reflected by the UV-Visible spectrum, and the qualitative and quantitative detection for Pb2+ is accomplished, with the detection range 0.5-4 µM and a detection limit of 0.5 µM. At the same time, Pb2+ in real water sample is detected. Furthermore, the high selectivity and low cost of the assay means it is promising for enviromental applications.

The Hydrological Sensitivity to Global Warming and Solar Geoengineering Derived from Thermodynamic Constraints

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

Kleidon, Alex; Kravitz, Benjamin S.; Renner, Maik

2015-01-16

We derive analytic expressions of the transient response of the hydrological cycle to surface warming from an extremely simple energy balance model in which turbulent heat fluxes are constrained by the thermodynamic limit of maximum power. For a given magnitude of steady-state temperature change, this approach predicts the transient response as well as the steady-state change in surface energy partitioning and the hydrologic cycle. We show that the transient behavior of the simple model as well as the steady state hydrological sensitivities to greenhouse warming and solar geoengineering are comparable to results from simulations using highly complex models. Many ofmore » the global-scale hydrological cycle changes can be understood from a surface energy balance perspective, and our thermodynamically-constrained approach provides a physically robust way of estimating global hydrological changes in response to altered radiative forcing.« less

Fabrication and performance of pressure-sensing device consisting of electret film and organic semiconductor

NASA Astrophysics Data System (ADS)

Kodzasa, Takehito; Nobeshima, Daiki; Kuribara, Kazunori; Uemura, Sei; Yoshida, Manabu

2017-04-01

We propose a new concept of a pressure-sensitive device that consists of an organic electret film and an organic semiconductor. This device exhibits high sensitivity and selectivity against various types of pressure. The sensing mechanism of this device originates from a modulation of the electric conductivity of the organic semiconductor film induced by the interaction between the semiconductor film and the charged electret film placed face to face. It is expected that a complicated sensor array will be fabricated by using a roll-to-roll manufacturing system, because this device can be prepared by an all-printing and simple lamination process without high-level positional adjustment for printing processes. This also shows that this device with a simple structure is suitable for application to a highly flexible device array sheet for an Internet of Things (IoT) or wearable sensing system.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

A simple model of space radiation damage in GaAs solar cells

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Stith, J. J.; Stock, L. V.

1983-01-01

A simple model is derived for the radiation damage of shallow junction gallium arsenide (GaAs) solar cells. Reasonable agreement is found between the model and specific experimental studies of radiation effects with electron and proton beams. In particular, the extreme sensitivity of the cell to protons stopping near the cell junction is predicted by the model. The equivalent fluence concept is of questionable validity for monoenergetic proton beams. Angular factors are quite important in establishing the cell sensitivity to incident particle types and energies. A fluence of isotropic incidence 1 MeV electrons (assuming infinite backing) is equivalent to four times the fluence of normal incidence 1 MeV electrons. Spectral factors common to the space radiations are considered, and cover glass thickness required to minimize the initial damage for a typical cell configuration is calculated. Rough equivalence between the geosynchronous environment and an equivalent 1 MeV electron fluence (normal incidence) is established.

CdTe quantum dot as a fluorescence probe for vitamin B12 in dosage form

NASA Astrophysics Data System (ADS)

Vaishnavi, E.; Renganathan, R.

2013-11-01

We here report the CdTe quantum dot (CdTe QDs)-based sensor for probing vitamin B12 derivatives in aqueous solution. In this paper, simple and sensitive fluorescence quenching measurements has been employed. The Stern-Volmer constant (KSV), quenching rate constant (kq) and binding constant (K) were rationalized from fluorescence quenching measurement. Furthermore, the fluorescence resonance energy transfer (FRET) mechanism was discussed. This method was applicable over the concentration ranging from 1 to 14 μg/mL (VB12) with correlation coefficient of 0.993. The limit of detection (LOD) of VB12 was found to be 0.15 μg/mL. Moreover, the present approach opens a simple pathway for developing cost-effective, sensitive and selective QD-based fluorescence sensors/probes for biologically significant VB12 in pharmaceutical sample with mean recoveries in the range of 100-102.1%.

Green light may improve diagnostic accuracy of nailfold capillaroscopy with a simple digital videomicroscope.

PubMed

Weekenstroo, Harm H A; Cornelissen, Bart M W; Bernelot Moens, Hein J

2015-06-01

Nailfold capillaroscopy is a non-invasive and safe technique for the analysis of microangiopathologies. Imaging quality of widely used simple videomicroscopes is poor. The use of green illumination instead of the commonly used white light may improve contrast. The aim of the study was to compare the effect of green illumination with white illumination, regarding capillary density, the number of microangiopathologies, and sensitivity and specificity for systemic sclerosis. Five rheumatologists have evaluated 80 images; 40 images acquired with green light, and 40 images acquired with white light. A larger number of microangiopathologies were found in images acquired with green light than in images acquired with white light. This results in slightly higher sensitivity with green light in comparison with white light, without reducing the specificity. These findings suggest that green instead of white illumination may facilitate evaluation of capillaroscopic images obtained with a low-cost digital videomicroscope.

Development of a loop-mediated isothermal amplification (LAMP) assay for rapid and specific detection of common genetically modified organisms (GMOs).

PubMed

Feng, Jiawang; Tang, Shiming; Liu, Lideng; Kuang, Xiaoshan; Wang, Xiaoyu; Hu, Songnan; You, Shuzhu

2015-03-01

Here, we developed a loop-mediated isothermal amplification (LAMP) assay for 11 common transgenic target DNA in GMOs. Six sets of LAMP primer candidates for each target were designed and their specificity, sensitivity, and reproductivity were evaluated. With the optimized LAMP primers, this LAMP assay was simply run within 45-60 min to detect all these targets in GMOs tested. The sensitivity, specificity, and reproductivity of the LAMP assay were further analyzed in comparison with those of Real-Time PCR. In consistent with real-time PCR, detection of 0.5% GMOs in equivalent background DNA was possible using this LAMP assay for all targets. In comparison with real-time PCR, the LAMP assay showed the same results with simple instruments. Hence, the LAMP assay developed can provide a rapid and simple approach for routine screening as well as specific events detection of many GMOs.

An Oxidase-Based Electrochemical Fluidic Sensor with High-Sensitivity and Low-Interference by On-Chip Oxygen Manipulation

PubMed Central

Radhakrishnan, Nitin; Park, Jongwon; Kim, Chang-Soo

2012-01-01

Utilizing a simple fluidic structure, we demonstrate the improved performance of oxidase-based enzymatic biosensors. Electrolysis of water is utilized to generate bubbles to manipulate the oxygen microenvironment close to the biosensor in a fluidic channel. For the proper enzyme reactions to occur, a simple mechanical procedure of manipulating bubbles was developed to maximize the oxygen level while minimizing the pH change after electrolysis. The sensors show improved sensitivities based on the oxygen dependency of enzyme reaction. In addition, this oxygen-rich operation minimizes the ratio of electrochemical interference signal by ascorbic acid during sensor operation (i.e., amperometric detection of hydrogen peroxide). Although creatinine sensors have been used as the model system in this study, this method is applicable to many other biosensors that can use oxidase enzymes (e.g., glucose, alcohol, phenol, etc.) to implement a viable component for in-line fluidic sensor systems. PMID:23012527

Highly stable aluminum-based metal-organic frameworks as biosensing platforms for assessment of food safety.

PubMed

Liu, Chun-Sen; Sun, Chun-Xiao; Tian, Jia-Yue; Wang, Zhuo-Wei; Ji, Hong-Fei; Song, Ying-Pan; Zhang, Shuai; Zhang, Zhi-Hong; He, Ling-Hao; Du, Miao

2017-05-15

Two unique immunosensors made of aluminum-based metal-organic frameworks (MOFs), namely, 515- and 516-MOFs, with 4,4',4''-nitrilotribenzoic acid (H 3 NTB) were successfully obtained to efficiently assess food safety. The as-prepared 515- and 516-MOFs exhibited superior thermal and physicochemical stability, high electrochemical activity, and good biocompatibility. Among these immunosensors, 516-MOF showed a preferable biosensing ability toward analytes determined by electrochemical techniques. The developed 516-MOF-based electrochemical biosensor not only demonstrated high sensitivity with low detection limits of 0.70 and 0.40pgmL -1 toward vomitoxin and salbutamol, respectively, but also showed good selectivity in the presence of other interferences. Therefore, with the advantages of high sensitivity, good selectivity, and simple operation, this new strategy is believed to exhibit great potential for simple and convenient detection of poisonous and harmful residues in food. Copyright © 2017 Elsevier B.V. All rights reserved.

CdTe quantum dot as a fluorescence probe for vitamin B(12) in dosage form.

PubMed

Vaishnavi, E; Renganathan, R

2013-11-01

We here report the CdTe quantum dot (CdTe QDs)-based sensor for probing vitamin B12 derivatives in aqueous solution. In this paper, simple and sensitive fluorescence quenching measurements has been employed. The Stern-Volmer constant (KSV), quenching rate constant (kq) and binding constant (K) were rationalized from fluorescence quenching measurement. Furthermore, the fluorescence resonance energy transfer (FRET) mechanism was discussed. This method was applicable over the concentration ranging from 1 to 14μg/mL (VB12) with correlation coefficient of 0.993. The limit of detection (LOD) of VB12 was found to be 0.15μg/mL. Moreover, the present approach opens a simple pathway for developing cost-effective, sensitive and selective QD-based fluorescence sensors/probes for biologically significant VB12 in pharmaceutical sample with mean recoveries in the range of 100-102.1%. Copyright © 2013 Elsevier B.V. All rights reserved.

A Simple Secure Hash Function Scheme Using Multiple Chaotic Maps

NASA Astrophysics Data System (ADS)

Ahmad, Musheer; Khurana, Shruti; Singh, Sushmita; AlSharari, Hamed D.

2017-06-01

The chaotic maps posses high parameter sensitivity, random-like behavior and one-way computations, which favor the construction of cryptographic hash functions. In this paper, we propose to present a novel hash function scheme which uses multiple chaotic maps to generate efficient variable-sized hash functions. The message is divided into four parts, each part is processed by a different 1D chaotic map unit yielding intermediate hash code. The four codes are concatenated to two blocks, then each block is processed through 2D chaotic map unit separately. The final hash value is generated by combining the two partial hash codes. The simulation analyses such as distribution of hashes, statistical properties of confusion and diffusion, message and key sensitivity, collision resistance and flexibility are performed. The results reveal that the proposed anticipated hash scheme is simple, efficient and holds comparable capabilities when compared with some recent chaos-based hash algorithms.

Comparing convective heat fluxes derived from thermodynamics to a radiative-convective model and GCMs

NASA Astrophysics Data System (ADS)

Dhara, Chirag; Renner, Maik; Kleidon, Axel

2015-04-01

The convective transport of heat and moisture plays a key role in the climate system, but the transport is typically parameterized in models. Here, we aim at the simplest possible physical representation and treat convective heat fluxes as the result of a heat engine. We combine the well-known Carnot limit of this heat engine with the energy balances of the surface-atmosphere system that describe how the temperature difference is affected by convective heat transport, yielding a maximum power limit of convection. This results in a simple analytic expression for convective strength that depends primarily on surface solar absorption. We compare this expression with an idealized grey atmosphere radiative-convective (RC) model as well as Global Circulation Model (GCM) simulations at the grid scale. We find that our simple expression as well as the RC model can explain much of the geographic variation of the GCM output, resulting in strong linear correlations among the three approaches. The RC model, however, shows a lower bias than our simple expression. We identify the use of the prescribed convective adjustment in RC-like models as the reason for the lower bias. The strength of our model lies in its ability to capture the geographic variation of convective strength with a parameter-free expression. On the other hand, the comparison with the RC model indicates a method for improving the formulation of radiative transfer in our simple approach. We also find that the latent heat fluxes compare very well among the approaches, as well as their sensitivity to surface warming. What our comparison suggests is that the strength of convection and their sensitivity in the climatic mean can be estimated relatively robustly by rather simple approaches.

The Optimal Cut-Off Value of Neutrophil-to-Lymphocyte Ratio for Predicting Prognosis in Adult Patients with Henoch–Schönlein Purpura

PubMed Central

Park, Chan Hyuk; Han, Dong Soo; Jeong, Jae Yoon; Eun, Chang Soo; Yoo, Kyo-Sang; Jeon, Yong Cheol; Sohn, Joo Hyun

2016-01-01

Background The development of gastrointestinal (GI) bleeding and end-stage renal disease (ESRD) can be a concern in the management of Henoch–Schönlein purpura (HSP). We aimed to evaluate whether the neutrophil-to-lymphocyte ratio (NLR) is associated with the prognosis of adult patients with HSP. Methods Clinical data including the NLR of adult patients with HSP were retrospectively analyzed. Patients were classified into three groups as follows: (a) simple recovery, (b) wax & wane without GI bleeding, and (c) development of GI bleeding. The optimal cut-off value was determined using a receiver operating characteristics curve and the Youden index. Results A total of 66 adult patients were enrolled. The NLR was higher in the GI bleeding group than in the simple recovery or wax & wane group (simple recovery vs. wax & wane vs. GI bleeding; median [IQR], 2.32 [1.61–3.11] vs. 3.18 [2.16–3.71] vs. 7.52 [4.91–10.23], P<0.001). For the purpose of predicting simple recovery, the optimal cut-off value of NLR was 3.18, and the sensitivity and specificity were 74.1% and 75.0%, respectively. For predicting development of GI bleeding, the optimal cut-off value was 3.90 and the sensitivity and specificity were 87.5% and 88.6%, respectively. Conclusions The NLR is useful for predicting development of GI bleeding as well as simple recovery without symptom relapse. Two different cut-off values of NLR, 3.18 for predicting an easy recovery without symptom relapse and 3.90 for predicting GI bleeding can be used in adult patients with HSP. PMID:27073884

Comparative analysis of multiple-casualty incident triage algorithms.

PubMed

Garner, A; Lee, A; Harrison, K; Schultz, C H

2001-11-01

We sought to retrospectively measure the accuracy of multiple-casualty incident (MCI) triage algorithms and their component physiologic variables in predicting adult patients with critical injury. We performed a retrospective review of 1,144 consecutive adult patients transported by ambulance and admitted to 2 trauma centers. Association between first-recorded out-of-hospital physiologic variables and a resource-based definition of severe injury appropriate to the MCI context was determined. The association between severe injury and Triage Sieve, Simple Triage and Rapid Treatment, modified Simple Triage and Rapid Treatment, and CareFlight Triage was determined in the patient population. Of the physiologic variables, the Motor Component of the Glasgow Coma Scale had the strongest association with severe injury, followed by systolic blood pressure. The differences between CareFlight Triage, Simple Triage and Rapid Treatment, and modified Simple Triage and Rapid Treatment were not dramatic, with sensitivities of 82% (95% confidence interval [CI] 75% to 88%), 85% (95% CI 78% to 90%), and 84% (95% CI 76% to 89%), respectively, and specificities of 96% (95% CI 94% to 97%), 86% (95% CI 84% to 88%), and 91% (95% CI 89% to 93%), respectively. Both forms of Triage Sieve were significantly poorer predictors of severe injury. Of the physiologic variables used in the triage algorithms, the Motor Component of the Glasgow Coma Scale and systolic blood pressure had the strongest association with severe injury. CareFlight Triage, Simple Triage and Rapid Treatment, and modified Simple Triage and Rapid Treatment had similar sensitivities in predicting critical injury in designated trauma patients, but CareFlight Triage had better specificity. Because patients in a true mass casualty situation may not be completely comparable with designated trauma patients transported to emergency departments in routine circumstances, the best triage instrument in this study may not be the best in an actual MCI. These findings must be validated prospectively before their accuracy can be confirmed.

Sensory Gain Outperforms Efficient Readout Mechanisms in Predicting Attention-Related Improvements in Behavior

PubMed Central

Ester, Edward F.; Deering, Sean

2014-01-01

Spatial attention has been postulated to facilitate perceptual processing via several different mechanisms. For instance, attention can amplify neural responses in sensory areas (sensory gain), mediate neural variability (noise modulation), or alter the manner in which sensory signals are selectively read out by postsensory decision mechanisms (efficient readout). Even in the context of simple behavioral tasks, it is unclear how well each of these mechanisms can account for the relationship between attention-modulated changes in behavior and neural activity because few studies have systematically mapped changes between stimulus intensity, attentional focus, neural activity, and behavioral performance. Here, we used a combination of psychophysics, event-related potentials (ERPs), and quantitative modeling to explicitly link attention-related changes in perceptual sensitivity with changes in the ERP amplitudes recorded from human observers. Spatial attention led to a multiplicative increase in the amplitude of an early sensory ERP component (the P1, peaking ∼80–130 ms poststimulus) and in the amplitude of the late positive deflection component (peaking ∼230–330 ms poststimulus). A simple model based on signal detection theory demonstrates that these multiplicative gain changes were sufficient to account for attention-related improvements in perceptual sensitivity, without a need to invoke noise modulation. Moreover, combining the observed multiplicative gain with a postsensory readout mechanism resulted in a significantly poorer description of the observed behavioral data. We conclude that, at least in the context of relatively simple visual discrimination tasks, spatial attention modulates perceptual sensitivity primarily by modulating the gain of neural responses during early sensory processing PMID:25274817

A simple and sensitive flow injection method based on the catalytic activity of CdS quantum dots in an acidic permanganate chemiluminescence system for determination of formaldehyde in water and wastewater.

PubMed

Khataee, Alireza; Lotfi, Roya; Hasanzadeh, Aliyeh; Iranifam, Mortaza

2016-04-01

A simple and sensitive flow injection chemiluminescence (CL) method in which CdS quantum dots (QDs) enhanced the CL intensity of a KMnO4-formaldehyde (HCHO) reaction was offered for the determination of HCHO. This CL system was based on the catalytic activity of CdS QDs and their participation in the CL resonance energy transfer (CRET) phenomenon. A possible mechanism for the supplied CL system was proposed using the kinetic curves of the CL systems and the spectra of CL, photoluminescence (PL) and ultraviolet-visible (UV-Vis). The emanated CL intensity of the KMnO4-CdS QDs system was amplified in the presence of a trace level of HCHO. Based on this enhancement effect, a simple and sensitive flow injection CL method was suggested for the determination of HCHO concentration in environmental water and wastewater samples. Under selected optimized experimental conditions, the increased CL intensity was proportional to the HCHO concentration in the range of 0.03-4.5 μg L(-1) and 4.5-10.0 μg L(-1). The detection limits (3σ) were 0.0003 μg L(-1) and 1.2 μg L(-1). The relative standard deviations (RSD%) for eleven replicate determinations of 4.0 μg L(-1) HCHO were 2.2%. Furthermore, the feasibility of the developed method was investigated via the determination of HCHO concentration in environmental water and wastewater samples.

Simple, sensitive, selective and validated spectrophotometric methods for the estimation of a biomarker trigonelline from polyherbal gels

NASA Astrophysics Data System (ADS)

Chopra, Shruti; Motwani, Sanjay K.; Ahmad, Farhan J.; Khar, Roop K.

2007-11-01

Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric methods were developed and validated for the estimation of trigonelline in bulk and pharmaceutical formulations. Trigonelline was estimated at 265 nm in deionised water and at 264 nm in phosphate buffer (pH 4.5). Beer's law was obeyed in the concentration ranges of 1-20 μg mL -1 ( r2 = 0.9999) in deionised water and 1-24 μg mL -1 ( r2 = 0.9999) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.04 × 10 3 L mol -1 cm -1 and 0.0422 μg cm -2/0.001A in deionised water; and 3.05 × 10 3 L mol -1 cm -1 and 0.0567 μg cm -2/0.001A in phosphate buffer media, respectively. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.12 and 0.37 μg mL -1 in deionised water and 0.13 and 0.40 μg mL -1 in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of trigonelline in pharmaceutical formulations (vaginal tablets and bioadhesive vaginal gels). The results demonstrated that the procedure is accurate, precise, specific and reproducible (percent relative standard deviation <2%), while being simple and less time consuming and hence can be suitably applied for the estimation of trigonelline in different dosage forms and dissolution studies.

The product of triglycerides and glucose, a simple measure of insulin sensitivity. Comparison with the euglycemic-hyperinsulinemic clamp.

PubMed

Guerrero-Romero, Fernando; Simental-Mendía, Luis E; González-Ortiz, Manuel; Martínez-Abundis, Esperanza; Ramos-Zavala, María G; Hernández-González, Sandra O; Jacques-Camarena, Omar; Rodríguez-Morán, Martha

2010-07-01

To meet the worldwide challenge of emerging diabetes, accessible and inexpensive tests to identify insulin resistance are needed. To evaluate the sensitivity and specificity of the product of fasting, we compared the triglycerides and glucose (TyG) index, a simple measure of insulin resistance, with the euglycemic-hyperinsulinemic clamp test. We conducted a cross-sectional study of the general population and outpatients of the Internal Medicine Department at the Medical Unit of High Specialty of the Specialty Hospital at the West National Medical Center in Guadalajara, Mexico. Eleven nonobese healthy subjects, 34 obese normal glucose tolerance individuals, 22 subjects with prediabetes, and 32 diabetic patients participated in the study. We performed a euglycemic-hyperinsulinemic clamp test. Sensitivity and specificity of the TyG index [Ln(fasting triglycerides) (mg/dl) x fasting glucose (mg/dl)/2] were measured, as well as the area under the curve of the receiver operating characteristic scatter plot and the correlation between the TyG index and the total glucose metabolism (M) rates. Pearson's correlation coefficient between the TyG index and M rates was -0.681 (P < 0.005). Correlation between the TyG index and M rates was similar between men (-0.740) and women (-0.730), nonobese (-0.705) and obese (-0.710), and nondiabetic (-0.670) and diabetic (-0.690) individuals. The best value of the TyG index for diagnosis of insulin resistance was 4.68, which showed the highest sensitivity (96.5%) and specificity (85.0%; area under the curve + 0.858). The TyG index has high sensitivity and specificity, suggesting that it could be useful for identification of subjects with decreased insulin sensitivity.

Modelling the dependence of contrast sensitivity on grating area and spatial frequency.

PubMed

Rovamo, J; Luntinen, O; Näsänen, R

1993-12-01

We modelled the human foveal visual system in a detection task as a simple image processor comprising (i) low-pass filtering due to the optical transfer function of the eye, (ii) high-pass filtering of neural origin, (iii) addition of internal neural noise, and (iv) detection by a local matched filter. Its detection efficiency for gratings was constant up to a critical area but then decreased with increasing area. To test the model we measured Michelson contrast sensitivity as a function of grating area at spatial frequencies of 0.125-32 c/deg for simple vertical and circular cosine gratings. In circular gratings luminance was sinusoidally modulated as a function of the radius of the grating field. In agreement with the model, contrast sensitivity at all spatial frequencies increased in proportion to the square-root of grating area at small areas. When grating area exceeded critical area, the increase saturated and contrast sensitivity became independent of area at large grating areas. Spatial integration thus obeyed Piper's law at small grating areas. The critical area of spatial integration, marking the cessation of Piper's law, was constant in solid degrees at low spatial frequencies but inversely proportional to spatial frequency squared at medium and high spatial frequencies. At low spatial frequencies the maximum contrast sensitivity obtainable by spatial integration increased in proportion to spatial frequency but at high spatial frequencies it decreased in proportion to the cube of the increasing spatial frequency. The increase was due to high-pass filtering of neural origin (lateral inhibition) and the decrease was mainly due to the optical transfer function of the eye. Our model explained 95% of the total variance of the contrast sensitivity data.

Single prolonged stress effects on sensitization to cocaine and cocaine self-administration in rats

PubMed Central

Eagle, Andrew L.; Singh, Robby; Kohler, Robert J.; Friedman, Amy L.; Liebowitz, Chelsea P.; Galloway, Matthew P.; Enman, Nicole M.; Jutkiewicz, Emily M.; Perrine, Shane A.

2017-01-01

Posttraumatic stress disorder (PTSD) is often comorbid with substance use disorders (SUD). Single prolonged stress (SPS) is a well-validated rat model of PTSD that provides a framework to investigate drug-induced behaviors as a preclinical model of the comorbidity. We hypothesized that cocaine sensitization and self-administration would be increased following exposure to SPS. Male Sprague–Dawley rats were exposed to SPS or control treatment. After SPS, cocaine (0,10 or 20mg/kg, i.p.) was administered for 5 consecutive days and locomotor activity was measured. Another cohort was assessed for cocaine self-administration (0.1 or 0.32 mg/kg/i.v.) after SPS. Rats were tested for acquisition, extinction and cue-induced reinstatement behaviors. Control animals showed a dose-dependent increase in cocaine-induced locomotor activity after acute cocaine whereas SPS rats did not. Using a sub-threshold sensitization paradigm, control rats did not exhibit enhanced locomotor activity at Day 5 and therefore did not develop behavioral sensitization, asexpected. However, compared to control ratson Day 5 the locomotor response to 20mg/kg repeated cocaine was greatly enhanced in SPS-treated rats, which exhibited enhanced cocaine locomotor sensitization. The effect of SPS on locomotor activity was unique in that SPS did not modify cocaine self-administration behaviors under a simple schedule of reinforcement. These data show that SPS differentially affects cocaine-mediated behaviors causing no effect to cocaine self-administration, under a simple schedule of reinforcement, but significantly augmenting cocaine locomotor sensitization. These results suggest that SPS shares common neurocircuitry with stimulant-induced plasticity, but dissociable from that underlying psychostimulant-induced reinforcement. PMID:25712697

Single prolonged stress effects on sensitization to cocaine and cocaine self-administration in rats.

PubMed

Eagle, Andrew L; Singh, Robby; Kohler, Robert J; Friedman, Amy L; Liebowitz, Chelsea P; Galloway, Matthew P; Enman, Nicole M; Jutkiewicz, Emily M; Perrine, Shane A

2015-05-01

Posttraumatic stress disorder (PTSD) is often comorbid with substance use disorders (SUD). Single prolonged stress (SPS) is a well-validated rat model of PTSD that provides a framework to investigate drug-induced behaviors as a preclinical model of the comorbidity. We hypothesized that cocaine sensitization and self-administration would be increased following exposure to SPS. Male Sprague-Dawley rats were exposed to SPS or control treatment. After SPS, cocaine (0, 10 or 20 mg/kg, i.p.) was administered for 5 consecutive days and locomotor activity was measured. Another cohort was assessed for cocaine self-administration (0.1 or 0.32 mg/kg/i.v.) after SPS. Rats were tested for acquisition, extinction and cue-induced reinstatement behaviors. Control animals showed a dose-dependent increase in cocaine-induced locomotor activity after acute cocaine whereas SPS rats did not. Using a sub-threshold sensitization paradigm, control rats did not exhibit enhanced locomotor activity at Day 5 and therefore did not develop behavioral sensitization, as expected. However, compared to control rats on Day 5 the locomotor response to 20mg/kg repeated cocaine was greatly enhanced in SPS-treated rats, which exhibited enhanced cocaine locomotor sensitization. The effect of SPS on locomotor activity was unique in that SPS did not modify cocaine self-administration behaviors under a simple schedule of reinforcement. These data show that SPS differentially affects cocaine-mediated behaviors causing no effect to cocaine self-administration, under a simple schedule of reinforcement, but significantly augmenting cocaine locomotor sensitization. These results suggest that SPS shares common neurocircuitry with stimulant-induced plasticity, but dissociable from that underlying psychostimulant-induced reinforcement. Copyright © 2015. Published by Elsevier B.V.

Protocol for the use of light upon extension real-time PCR for the determination of viral load in HBV infection.

PubMed

Li, Guimin; Li, Wangfeng; Liu, Lixia

2012-01-01

Real-time PCR has engendered wide acceptance for quantitation of hepatitis B virus (HBV) DNA in the blood due to its improved rapidity, sensitivity, reproducibility, and reduced contamination. Here we describe a cost-effective and highly sensitive HBV real-time quantitative assay based on the light upon extension real-time PCR platform and a simple and reliable HBV DNA preparation method using silica-coated magnetic beads.

Sensitivity of measurement-based purification processes to inner interactions

NASA Astrophysics Data System (ADS)

Militello, Benedetto; Napoli, Anna

2018-02-01

The sensitivity of a repeated measurement-based purification scheme to additional undesired couplings is analyzed, focusing on the very simple and archetypical system consisting of two two-level systems interacting with a repeatedly measured one. Several regimes are considered and in the strong coupling limit (i.e., when the coupling constant of the undesired interaction is very large) the occurrence of a quantum Zeno effect is proven to dramatically jeopardize the efficiency of the purification process.

Re-scan confocal microscopy: scanning twice for better resolution

PubMed Central

De Luca, Giulia M.R.; Breedijk, Ronald M.P.; Brandt, Rick A.J.; Zeelenberg, Christiaan H.C.; de Jong, Babette E.; Timmermans, Wendy; Azar, Leila Nahidi; Hoebe, Ron A.; Stallinga, Sjoerd; Manders, Erik M.M.

2013-01-01

We present a new super-resolution technique, Re-scan Confocal Microscopy (RCM), based on standard confocal microscopy extended with an optical (re-scanning) unit that projects the image directly on a CCD-camera. This new microscope has improved lateral resolution and strongly improved sensitivity while maintaining the sectioning capability of a standard confocal microscope. This simple technology is typically useful for biological applications where the combination high-resolution and high-sensitivity is required. PMID:24298422

Separation of gonadotropic fractions with different species specificities from tuna pituitaries

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

Ando, H.; Ishii, S.

1988-05-01

Eight different gonadotropic glycoprotein fractions were separated from the acetone-dried powder of yellow fin tuna pituitary glands by successive chromatographies on Superose 12 for gel filtration and Mono Q for anion exchange using the Pharmacia fast protein liquid chromatography system. This was preceded by preliminary separations using an ammonium sulfate precipitation method and affinity chromatography on concanavalin A-Sepharose. For biological characterization, we employed two radioreceptor assay systems, one using goby testis plasma membranes and silver carp GTH as the receptor and radioligand, respectively, and the other using testis plasma membranes of the yellow fin tuna and gonadotropin of the samemore » species, respectively. We also employed two testicular cyclic AMP accumulation bioassay methods in vitro, one with the goby testis and the other with the mackerel testis. The least acidic fraction after Mono Q was further separated into four subfractions by rechromatography with Mono Q. They were strongly active in the tuna and mackerel assays but almost inactive in the goby assays. They were referred to as tuna-type tuna gonadotropin. In contrast, the most acidic fraction obtained after the first Mono Q was active in the goby assays but almost inactive in the tuna and mackerel assays. It was referred to as goby-type tuna gonadotropin. The intermediate fractions were active on both assays and are considered to be mixtures of tuna-type and goby-type gonadotropins. The reason for the presence of gonadotropin inactive to homologous species is discussed from the evolutionary viewpoint.« less

Clinical Significance of Thyrotrophin Binding Inhibitor Immunoglobulins in Patients with Graves’ Disease and Various Types of Thyroiditis

PubMed Central

Lee, Chong Suk; Kim, Doo Man; Kim, Chong Soon; Yoo, Hyung Joon

1987-01-01

It is well known that thyrotrophin receptor antibodies are present in the sera of patients with autoimmune thyroid disease. There is now compelling evidence that the hyperthyroidism of Graves’ disease is due to antibodies to the thyrotrophin (TSH) receptor. The measurement of these antibodies is valuable in the diagnosis and monitoring of Graves’ disease and in predicting the outcome of treatment. In the present study, thyrotrophin binding inhibitor immunoglobulin (TBII) activites were measured by radioreceptor assay, according to the method of Shewring and Smith1), in 30 patients with Graves’ disease, 13 patients with Hashimoto’s thyroiditis, 20 patients with lymphocytic thyroiditis with spontaneously resolving hyperthyroidism (LT-SRH), 5 patients with postpartum thyroiditis, and 7 patients with subacute thyroiditis. The TBII activity results a mean of 3.0±3.0% in normal controls, 44.8±8.7% in Graves’ disease, 8.69±8.06% in Hashimoto’s thyroiditis, 7.63±2.32% in LT-SRH, 3.33±1.16% in postpartum thyroiditis, and 2.67±2.33% in subacute thyroiditis respectively. These clinical and laboratory findings show that TBII also plays a role in the pathogenesis of Graves’ disease. The levels of the TBII activties in Hashimoto’s thyroiditis and LT-SRH, suggest a pathognomic role similar to that of Graves’ disease in above mentioned two disease, but that TBII activity is not significant in postpartum or subacute thyroiditis. PMID:2908728

Leukemia inhibitory factor protects against experimental lethal Escherichia coli septic shock in mice.

PubMed Central

Waring, P M; Waring, L J; Billington, T; Metcalf, D

1995-01-01

Leukemia inhibitory factor (LIF) has recently been associated with septic shock in humans. In this study we sought to determine, in mice, the role of LIF in septic shock. During sublethal endotoxemia, serum LIF levels, as determined by radio-receptor competition assay, peaked at 2 h and were low (3 ng/ml), whereas in lethal Escherichia coli septic shock serum LIF levels rose progressively (> 30 ng/ml) in the premorbid phase coincident with the development of tissue injury. Single i.v. injections of high doses (up to 50 micrograms per mouse) of recombinant murine LIF had no obvious acute detrimental effects, whereas continued i.p. administration (30 micrograms per mouse per day) for 3-4 days induced a fatal catabolic state without evidence of preceding hemodynamic collapse or shock. Simultaneous or subsequent administration of high doses of LIF had no effect on mortality from sublethal and lethal E. coli septic shock, whereas prior administration conferred significant protection against lethality (P << 0.001 by log-rank test), an effect that was dose and interval dependent. This protective effect resembled endotoxin tolerance and was characterized by suppression of E. coli-induced serum tumor necrosis factor concentration (P < 0.05), reduction in the number of viable bacteria (P < 0.05), and prevention of sepsis-induced tissue injury. These observations suggest that systemic LIF production is part of the host response to both endotoxin and sepsis-induced tissue injury. Images Fig. 2 Fig. 5 PMID:7877978

Multiscale Hierarchical Design of a Flexible Piezoresistive Pressure Sensor with High Sensitivity and Wide Linearity Range.

PubMed

Shi, Jidong; Wang, Liu; Dai, Zhaohe; Zhao, Lingyu; Du, Mingde; Li, Hongbian; Fang, Ying

2018-05-30

Flexible piezoresistive pressure sensors have been attracting wide attention for applications in health monitoring and human-machine interfaces because of their simple device structure and easy-readout signals. For practical applications, flexible pressure sensors with both high sensitivity and wide linearity range are highly desirable. Herein, a simple and low-cost method for the fabrication of a flexible piezoresistive pressure sensor with a hierarchical structure over large areas is presented. The piezoresistive pressure sensor consists of arrays of microscale papillae with nanoscale roughness produced by replicating the lotus leaf's surface and spray-coating of graphene ink. Finite element analysis (FEA) shows that the hierarchical structure governs the deformation behavior and pressure distribution at the contact interface, leading to a quick and steady increase in contact area with loads. As a result, the piezoresistive pressure sensor demonstrates a high sensitivity of 1.2 kPa -1 and a wide linearity range from 0 to 25 kPa. The flexible pressure sensor is applied for sensitive monitoring of small vibrations, including wrist pulse and acoustic waves. Moreover, a piezoresistive pressure sensor array is fabricated for mapping the spatial distribution of pressure. These results highlight the potential applications of the flexible piezoresistive pressure sensor for health monitoring and electronic skin. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultra-sensitive speciation analysis of mercury by CE-ICP-MS together with field-amplified sample stacking injection and dispersive solid-phase extraction.

PubMed

Chen, YiQuan; Cheng, Xian; Mo, Fan; Huang, LiMei; Wu, Zujian; Wu, Yongning; Xu, LiangJun; Fu, FengFu

2016-04-01

A simple dispersive solid-phase extraction (DSPE) used to extract and preconcentrate ultra-trace MeHg, EtHg and Hg(2+) from water sample, and a sensitive method for the simultaneous analysis of MeHg, EtHg and Hg(2+) by using capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) with field-amplified sample stacking injection (FASI) were first reported in this study. The DSPE used thiol cotton particles as adsorbent, and is simple and effective. It can be used to extract and preconcentrate ultra-trace mercury compounds in water samples within 30 min with a satisfied recovery and no mercury species alteration during the process. The FASI enhanced the sensitivity of CE-ICP-MS with 25-fold, 29-fold and 27-fold for MeHg, EtHg and Hg(2+) , respectively. Using FASI-CE-ICP-MS together with DSPE, we have successfully determined ultra-trace MeHg, EtHg and Hg(2+) in tap water with a limits of quantification (LOQs) of 0.26-0.45 pg/mL, an RSD (n = 3) < 6% and a recovery of 92-108%. Ultra-high sensitivity, as well as much less sample and reagent consumption and low operating cost, make our method a valuable technique to the speciation analysis of ultra-trace mercury. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed Central

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

2013-01-01

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

Ratiometric near infrared luminescent thermometer based on lanthanide metal-organic frameworks

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

Yue, Dan; Zhang, Jun; Zhao, Dian

2016-09-15

A near infrared luminescent MOFs thermometer (Nd{sub 0.676}Yb{sub 0.324}BTC) was prepared via a simple solvothermal method using Ln{sup 3+} (Ln=Nd, Yb) ions and 1, 3, 5-benznenetricarboxylic acid (H{sub 3}BTC), and characterized by PXRD, TGA, ICP, and photoluminescence (PL) spectrum. These results indicate that the Nd{sub 0.676}Yb{sub 0.324}BTC displays high relative sensitivity and excellent repeatability in the physiological temperature range (288–323 K), and the maximum relative sensitivity is determined to be 1.187% K{sup −1} at 323 K. These NIR luminescent MOFs may have potential applications in physiological temperature sensing. - Graphical abstract: A near infrared luminescent MOFs thermometer (Nd{sub 0.054}Yb{sub 0.946}BTCmore » ) displays high relative sensitivity and excellent repeatability in the physiological temperature range (288–323 K). Display Omitted - Highlights: • A ratiometric near infrared luminescent MOFs thermometer (Nd{sub 0.676}Yb{sub 0.324}BTC) was prepared via a simple solvothermal method. • The maximum relative sensitivity of Nd{sub 0.676}Yb{sub 0.324}BTC is determined to be 1.187% K{sup −1} at 323 K. • Nd{sub 0.676}Yb{sub 0.324}BTC showed excellent repeatability in the physiological temperature range (288–323 K).« less

Chloroplast avoidance movement as a sensitive indicator of relative water content during leaf desiccation in the dark.

PubMed

Nauš, Jan; Šmecko, Slavomír; Špundová, Martina

2016-08-01

In the context of global climate change, drought is one of the major stress factors with negative effect on photosynthesis and plant productivity. Currently, chlorophyll fluorescence parameters are widely used as indicators of plant stress, mainly owing to the rapid, non-destructive and simple measurements this technique allows. However, these parameters have been shown to have limited sensitivity for the monitoring of water deficit as leaf desiccation has relatively small effect on photosystem II photochemistry. In this study, we found that blue light-induced increase in leaf transmittance reflecting chloroplast avoidance movement was much more sensitive to a decrease in relative water content (RWC) than chlorophyll fluorescence parameters in dark-desiccating leaves of tobacco (Nicotiana tabacum L.) and barley (Hordeum vulgare L.). Whereas the inhibition of chloroplast avoidance movement was detectable in leaves even with a small RWC decrease, the chlorophyll fluorescence parameters (F V/F M, V J, Ф PSII, NPQ) changed markedly only when RWC dropped below 70 %. For this reason, we propose light-induced chloroplast avoidance movement as a sensitive indicator of the decrease in leaf RWC. As our measurement of chloroplast movement using collimated transmittance is simple and non-destructive, it may be more suitable in some cases for the detection of plant stresses including water deficit than the conventionally used chlorophyll fluorescence methods.

Simple, multiplexed, PCR-based barcoding of DNA enables sensitive mutation detection in liquid biopsies using sequencing.

PubMed

Ståhlberg, Anders; Krzyzanowski, Paul M; Jackson, Jennifer B; Egyud, Matthew; Stein, Lincoln; Godfrey, Tony E

2016-06-20

Detection of cell-free DNA in liquid biopsies offers great potential for use in non-invasive prenatal testing and as a cancer biomarker. Fetal and tumor DNA fractions however can be extremely low in these samples and ultra-sensitive methods are required for their detection. Here, we report an extremely simple and fast method for introduction of barcodes into DNA libraries made from 5 ng of DNA. Barcoded adapter primers are designed with an oligonucleotide hairpin structure to protect the molecular barcodes during the first rounds of polymerase chain reaction (PCR) and prevent them from participating in mis-priming events. Our approach enables high-level multiplexing and next-generation sequencing library construction with flexible library content. We show that uniform libraries of 1-, 5-, 13- and 31-plex can be generated. Utilizing the barcodes to generate consensus reads for each original DNA molecule reduces background sequencing noise and allows detection of variant alleles below 0.1% frequency in clonal cell line DNA and in cell-free plasma DNA. Thus, our approach bridges the gap between the highly sensitive but specific capabilities of digital PCR, which only allows a limited number of variants to be analyzed, with the broad target capability of next-generation sequencing which traditionally lacks the sensitivity to detect rare variants. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Development and validation of a simple and sensitive method for quantification of levodopa and carbidopa in rat and monkey plasma using derivatization and UPLC-MS/MS.

PubMed

Junnotula, Venkatraman; Licea-Perez, Hermes

2013-05-01

A simple, selective, and sensitive quantitative method has been developed for the simultaneous determination of levodopa and carbidopa in rat and monkey plasma by protein precipitation using acetonitrile containing the derivatizing reagent, flourescamine. Derivatized products of levodopa and carbidopa were separated on a BEH C18 column (2.1 mm × 50 mm; 1.7 μm particle size) using ultra high performance liquid chromatography (UHPLC) without any further purification. Tandem mass spectrometry (MS/MS) was used for detection. The method was validated over the concentration range of 5-5000 ng/mL and 3-3000 ng/mL for levodopa and carbidopa, respectively in rat and monkey plasma. Due to the poor stability of the investigated analytes in biological matrices, a mixture of sodium metabisulfite and hydrazine dihydrochloride was used as a stabilizer. This method was successfully utilized to support pharmacokinetic studies in both species. The results from assay validations and incurred samples re-analysis show that the method is selective, sensitive and robust. To our knowledge, this is the first UHPLC-MS/MS based method that utilizes derivatization with fluorescamine and provides adequate sensitivity for both levodopa and carbidopa with 50 μL of sample and a run time of 3.5 min. Copyright © 2013 Elsevier B.V. All rights reserved.

Insulin sensitivity indices: a proposal of cut-off points for simple identification of insulin-resistant subjects.

PubMed

Radikova, Z; Koska, J; Huckova, M; Ksinantova, L; Imrich, R; Vigas, M; Trnovec, T; Langer, P; Sebokova, E; Klimes, I

2006-05-01

Demanding measurement of insulin sensitivity using clamp methods does not simplify the identification of insulin resistant subjects in the general population. Other approaches such as fasting- or oral glucose tolerance test-derived insulin sensitivity indices were proposed and validated with the euglycemic clamp. Nevertheless, a lack of reference values for these indices prevents their wider use in epidemiological studies and clinical practice. The aim of our study was therefore to define the cut-off points of insulin resistance indices as well as the ranges of the most frequently obtained values for selected indices. A standard 75 g oral glucose tolerance test was carried out in 1156 subjects from a Caucasian rural population with no previous evidence of diabetes or other dysglycemias. Insulin resistance/sensitivity indices (HOMA-IR, HOMA-IR2, ISI Cederholm, and ISI Matsuda) were calculated. The 75th percentile value as the cut-off point to define IR corresponded with a HOMA-IR of 2.29, a HOMA-IR2 of 1.21, a 25th percentile for ISI Cederholm, and ISI Matsuda of 57 and 5.0, respectively. For the first time, the cut-off points for selected indices and their most frequently obtained values were established for groups of subjects as defined by glucose homeostasis and BMI. Thus, insulin-resistant subjects can be identified using this simple approach.

SiMa Cells for a Serotype Specific and Sensitive Cell-Based Neutralization Test for Botulinum Toxin A and E.

PubMed

Bak, Nicola; Rajagopal, Shalini; Stickings, Paul; Sesardic, Dorothea

2017-07-20

Botulinum toxins (BoNTs), of which there are seven serotypes, are among the most potent neurotoxins, with serotypes A, B and E causing human botulism. Antitoxins form the first line of treatment for botulism, and functional, highly sensitive in vitro methods for toxin neutralization are needed to replace the current in vivo methods used for determination of antitoxin potency. In this preliminary proof of concept study, we report the development of a neutralization test using the neuroblastoma SiMa cell line. The assay is serotype specific for either BoNT/A or BoNT/E, which both cleave unique sequences on SNAP-25 within SiMa cells. The end point is simple immunodetection of cleaved SNAP-25 from cell lysates with antibodies detecting only the newly exposed sequence on SNAP-25. Neutralizing antibodies prevent the toxin-induced cleavage of SNAP-25. The toxin neutralization assay, with an EC50 of ~2 mIU/mL determined with a standardized reference antiserum, is more sensitive than the mouse bioassays. Relevance was demonstrated with commercial and experimental antitoxins targeting different functional domains, and of known in vivo neutralizing activities. This is the first report describing a simple, specific, in vitro cell-based assay for the detection of neutralizing antibodies against BoNT/A and BoNT/E with a sensitivity exceeding that of the mouse bioassay.

SiMa Cells for a Serotype Specific and Sensitive Cell-Based Neutralization Test for Botulinum Toxin A and E

PubMed Central

Bak, Nicola; Rajagopal, Shalini; Stickings, Paul; Sesardic, Dorothea

2017-01-01

Botulinum toxins (BoNTs), of which there are seven serotypes, are among the most potent neurotoxins, with serotypes A, B and E causing human botulism. Antitoxins form the first line of treatment for botulism, and functional, highly sensitive in vitro methods for toxin neutralization are needed to replace the current in vivo methods used for determination of antitoxin potency. In this preliminary proof of concept study, we report the development of a neutralization test using the neuroblastoma SiMa cell line. The assay is serotype specific for either BoNT/A or BoNT/E, which both cleave unique sequences on SNAP-25 within SiMa cells. The end point is simple immunodetection of cleaved SNAP-25 from cell lysates with antibodies detecting only the newly exposed sequence on SNAP-25. Neutralizing antibodies prevent the toxin-induced cleavage of SNAP-25. The toxin neutralization assay, with an EC50 of ~2 mIU/mL determined with a standardized reference antiserum, is more sensitive than the mouse bioassays. Relevance was demonstrated with commercial and experimental antitoxins targeting different functional domains, and of known in vivo neutralizing activities. This is the first report describing a simple, specific, in vitro cell-based assay for the detection of neutralizing antibodies against BoNT/A and BoNT/E with a sensitivity exceeding that of the mouse bioassay. PMID:28726719

Rapid detection of bacteria in foods and biological fluids

NASA Technical Reports Server (NTRS)

Fealey, R. D.; Renner, W.

1973-01-01

Simple and inexpensive apparatus, called "redox monitoring cell," rapidly detects presence of bacteria. Bacteria is detected by measuring drop in oxygen content in test solution. Apparatus consists of vial with two specially designed electrodes connected to sensitive voltmeter.

Therapeutic Drug Monitoring of Phenytoin by Simple, Rapid, Accurate, Highly Sensitive and Novel Method and Its Clinical Applications.

PubMed

Shaikh, Abdul S; Guo, Ruichen

2017-01-01

Phenytoin has very challenging pharmacokinetic properties. To prevent its toxicity and ensure efficacy, continuous therapeutic monitoring is required. It is hard to get a simple, accurate, rapid, easily available, economical and highly sensitive assay in one method for therapeutic monitoring of phenytoin. The present study is directed towards establishing and validating a simpler, rapid, an accurate, highly sensitive, novel and environment friendly liquid chromatography/mass spectrometry (LC/MS) method for offering rapid and reliable TDM results of phenytoin in epileptic patients to physicians and clinicians for making immediate and rational decision. 27 epileptics patients with uncontrolled seizures or suspected of non-compliance or toxicity of phenytoin were selected and advised for TDM of phenytoin by neurologists of Qilu Hospital Jinan, China. The LC/MS assay was used for performing of therapeutic monitoring of phenytoin. The Agilent 1100 LC/MS system was used for TDM. The mixture of Ammonium acetate 5mM: Methanol at (35: 65 v/v) was used for the composition of mobile phase. The Diamonsil C18 (150mm×4.6mm, 5μm) column was used for the extraction of analytes in plasma. The samples were prepared with one step simple protein precipitation method. The technique was validated with the guidelines of International Conference on Harmonisation (ICH). The calibration curve demonstrated decent linearity within (0.2-20 µg/mL) concentration range with linearity equation, y= 0.0667855 x +0.00241785 and correlation coefficient (R2) of 0.99928. The specificity, recovery, linearity, accuracy, precision and stability results were within the accepted limits. The concentration of 0.2 µg/mL was observed as lower limit of quantitation (LLOQ), which is 12.5 times lower than the currently available enzyme-multiplied immunoassay technique (EMIT) for measurement of phenytoin in epilepsy patients. A rapid, simple, economical, precise, highly sensitive and novel LC/MS assay has been established, validated and applied successfully in TDM of 27 epileptics patients. It was alarmingly found that TDM results of all these patients were out of safe range except two patients. However, it needs further evaluation. Besides TDM, the stated method can also be applied in bioequivalence, pharmacokinetics, toxicokinetics and pharmacovigilance studies. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

On determining important aspects of mathematical models: Application to problems in physics and chemistry

NASA Technical Reports Server (NTRS)

Rabitz, Herschel

1987-01-01

The use of parametric and functional gradient sensitivity analysis techniques is considered for models described by partial differential equations. By interchanging appropriate dependent and independent variables, questions of inverse sensitivity may be addressed to gain insight into the inversion of observational data for parameter and function identification in mathematical models. It may be argued that the presence of a subset of dominantly strong coupled dependent variables will result in the overall system sensitivity behavior collapsing into a simple set of scaling and self similarity relations amongst elements of the entire matrix of sensitivity coefficients. These general tools are generic in nature, but herein their application to problems arising in selected areas of physics and chemistry is presented.

Sensitive determination of carbohydrates by fluorimetric method with Ce(IV) and sodium triphosphate.

PubMed

Yang, Jinghe; Cao, Xihui; Sun, Changxia; Wu, Xia; Li, Lei

2004-05-01

A new simple and sensitive fluorimetric method for the determination of carbohydrates is described. The method is based on the reaction between carbohydrates and Ce(IV) in the presence of sulfuric acid. All the reductive carbohydrates can be detected indirectly by the fluorescence of Ce(III) produced. The addition of sodium triphate enhances the sensitivity of the method by more than 10-folds. Under optimum conditions, an excellent linear relationship was obtained between the fluorescence intensity and the concentration of carbohydrates. The limits of detection lie in the range of 9.3 x 10(-10) - 1.3 x 10(-9) mol/L. As compared to the normal fluorimetric method, the proposed method is faster and more sensitive.

An electrochemical acetylcholine sensor based on lichen-like nickel oxide nanostructure.

PubMed

Sattarahmady, N; Heli, H; Vais, R Dehdari

2013-10-15

Lichen-like nickel oxide nanostructure was synthesized by a simple method and characterized. The nanostructure was then applied to modify a carbon paste electrode and for the fabrication of a sensor, and the electrocatalytic oxidation of acetylcholine (ACh) on the modified electrode was investigated. The electrocatalytic efficiency of the nickel oxide nanostructure was compared with nickel micro- and nanoparticles, and the lichen-like nickel oxide nanostructure showed the highest efficiency. The mechanism and kinetics of the electrooxidation process were investigated by cyclic voltammetry, steady-state polarization curve and chronoamperometry. The catalytic rate constant and the charge transfer coefficient of ACh electrooxidation by the active nickel species, and the diffusion coefficient of ACh were reported. A sensitive and time-saving hydrodynamic amperometry method was developed for the determination of ACh. ACh was determined with a sensitivity of 392.4 mA M⁻¹ cm⁻² and a limit of detection of 26.7 μM. The sensor had the advantages of simple fabrication method without using any enzyme or reagent and immobilization step, high electrocatalytic activity, very high sensitivity, long-term stability, and antifouling surface property toward ACh and its oxidation product. Copyright © 2013 Elsevier B.V. All rights reserved.

Ultrasonic monitoring of droplets' evaporation: Application to human whole blood.

PubMed

Laux, D; Ferrandis, J Y; Brutin, D

2016-09-01

During a colloidal droplet evaporation, a sol-gel transition can be observed and is described by the desiccation time τD and the gelation time τG. These characteristic times, which can be linked to viscoelastic properties of the droplet and to its composition, are classically rated by analysis of mass droplet evolution during evaporation. Even if monitoring mass evolution versus time seems straightforward, this approach is very sensitive to environmental conditions (vibrations, air flow…) as mass has to be evaluated very accurately using ultra-sensitive weighing scales. In this study we investigated the potentialities of ultrasonic shear reflectometry to assess τD and τG in a simple and reliable manner. In order to validate this approach, our study has focused on blood droplets evaporation on which a great deal of work has recently been published. Desiccation and gelation times measured with shear ultrasonic reflectometry have been perfectly correlated to values obtained from mass versus time analysis. This ultrasonic method which is not very sensitive to environmental perturbations is therefore very interesting to monitor the drying of blood droplets in a simple manner and is more generally suitable for complex fluid droplets evaporation investigation. Copyright © 2016 Elsevier B.V. All rights reserved.

A simple, fast and sensitive screening LC-ESI-MS/MS method for antibiotics in fish.

PubMed

Guidi, Letícia Rocha; Santos, Flávio Alves; Ribeiro, Ana Cláudia S R; Fernandes, Christian; Silva, Luiza H M; Gloria, Maria Beatriz A

2017-01-15

The objective of this study was to develop and validate a fast, sensitive and simple liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method for the screening of six classes of antibiotics (aminoglycosides, beta-lactams, macrolides, quinolones, sulfonamides and tetracyclines) in fish. Samples were extracted with trichloroacetic acid. LC separation was achieved on a Zorbax Eclipse XDB C18 column and gradient elution using 0.1% heptafluorobutyric acid in water and acetonitrile as mobile phase. Analysis was carried out in multiple reaction monitoring mode via electrospray interface operated in the positive ionization mode, with sulfaphenazole as internal standard. The method was suitable for routine screening purposes of 40 antibiotics, according to EC Guidelines for the Validation of Screening Methods for Residues of Veterinary Medicines, taking into consideration threshold value, cut-off factor, detection capability, limit of detection, sensitivity and specificity. Real fish samples (n=193) from aquaculture were analyzed and 15% were positive for enrofloxacin (quinolone), one of them at a higher concentration than the level of interest (50µgkg -1 ), suggesting possible contamination or illegal use of that antibiotic. Copyright © 2016 Elsevier B.V. All rights reserved.

The Role of Nanoparticle Design in Determining Analytical Performance of Lateral Flow Immunoassays.

PubMed

Zhan, Li; Guo, Shuang-Zhuang; Song, Fayi; Gong, Yan; Xu, Feng; Boulware, David R; McAlpine, Michael C; Chan, Warren C W; Bischof, John C

2017-12-13

Rapid, simple, and cost-effective diagnostics are needed to improve healthcare at the point of care (POC). However, the most widely used POC diagnostic, the lateral flow immunoassay (LFA), is ∼1000-times less sensitive and has a smaller analytical range than laboratory tests, requiring a confirmatory test to establish truly negative results. Here, a rational and systematic strategy is used to design the LFA contrast label (i.e., gold nanoparticles) to improve the analytical sensitivity, analytical detection range, and antigen quantification of LFAs. Specifically, we discovered that the size (30, 60, or 100 nm) of the gold nanoparticles is a main contributor to the LFA analytical performance through both the degree of receptor interaction and the ultimate visual or thermal contrast signals. Using the optimal LFA design, we demonstrated the ability to improve the analytical sensitivity by 256-fold and expand the analytical detection range from 3 log 10 to 6 log 10 for diagnosing patients with inflammatory conditions by measuring C-reactive protein. This work demonstrates that, with appropriate design of the contrast label, a simple and commonly used diagnostic technology can compete with more expensive state-of-the-art laboratory tests.

A rapid molecular diagnosis of cutaneous leishmaniasis by colorimetric malachite green-loop-mediated isothermal amplification (LAMP) combined with an FTA card as a direct sampling tool.

PubMed

Nzelu, Chukwunonso O; Cáceres, Abraham G; Guerrero-Quincho, Silvia; Tineo-Villafuerte, Edwin; Rodriquez-Delfin, Luis; Mimori, Tatsuyuki; Uezato, Hiroshi; Katakura, Ken; Gomez, Eduardo A; Guevara, Angel G; Hashiguchi, Yoshihisa; Kato, Hirotomo

2016-01-01

Leishmaniasis remains one of the world's most neglected diseases, and early detection of the infectious agent, especially in developing countries, will require a simple and rapid test. In this study, we established a quick, one-step, single-tube, highly sensitive loop-mediated isothermal amplification (LAMP) assay for rapid detection of Leishmania DNA from tissue materials spotted on an FTA card. An FTA-LAMP with pre-added malachite green was performed at 64°C for 60min using a heating block and/or water bath and DNA amplification was detected immediately after incubation. The LAMP assay had high detection sensitivity down to a level of 0.01 parasites per μl. The field- and clinic-applicability of the colorimetric FTA-LAMP assay was demonstrated with 122 clinical samples collected from patients suspected of having cutaneous leishmaniasis in Peru, from which 71 positives were detected. The LAMP assay in combination with an FTA card described here is rapid and sensitive, as well as simple to perform, and has great potential usefulness for diagnosis and surveillance of leishmaniasis in endemic areas. Copyright © 2015 Elsevier B.V. All rights reserved.

Improving the Power Conversion Efficiency of Carbon Quantum Dot-Sensitized Solar Cells by Growing the Dots on a TiO₂ Photoanode In Situ.

PubMed

Zhang, Quanxin; Zhang, Geping; Sun, Xiaofeng; Yin, Keyang; Li, Hongguang

2017-05-31

Dye-sensitized solar cells (DSSCs) are highly promising since they can potentially solve global energy issues. The development of new photosensitizers is the key to fully realizing perspectives proposed to DSSCs. Being cheap and nontoxic, carbon quantum dots (CQDs) have emerged as attractive candidates for this purpose. However, current methodologies to build up CQD-sensitized solar cells (CQDSCs) result in an imperfect apparatus with extremely low power conversion efficiencies (PCEs). Herein, we present a simple strategy of growing carbon quantum dots (CQDs) onto TiO₂ surfaces in situ. The CQDs/TiO₂ hybridized photoanode was then used to construct solar cell with an improved PCE of 0.87%, which is higher than all of the reported CQDSCs adopting the simple post-adsorption method. This result indicates that an in situ growing strategy has great advantages in terms of optimizing the performance of CQDSCs. In addition, we have also found that the mechanisms dominating the performance of CQDSCs are different from those behind the solar cells using inorganic semiconductor quantum dots (ISQDs) as the photosensitizers, which re-confirms the conclusion that the characteristics of CQDs differ from those of ISQDs.

Liquid density analysis of sucrose and alcoholic beverages using polyimide guided Love-mode acoustic wave sensors

NASA Astrophysics Data System (ADS)

Turton, Andrew; Bhattacharyya, Debabrata; Wood, David

2006-02-01

A liquid density sensor using Love-mode acoustic waves has been developed which is suitable for use in the food and drinks industries. The sensor has an open flat surface allowing immersion into a sample and simple cleaning. A polyimide waveguide layer allows cheap and simple fabrication combined with a robust chemically resistant surface. The low shear modulus of polyimide allows thin guiding layers giving a high sensitivity. A dual structure with a smooth reference device exhibiting viscous coupling with the wave, and a patterned sense area to trap the liquid causing mass loading, allows discrimination of the liquid density from the square root of the density-viscosity product (ρη)0.5. Frequency shift and insertion loss change were proportional to (ρη)0.5 with a non-linear response due to the non-Newtonian nature of viscous liquids at high frequencies. Measurements were made with sucrose solutions up to 50% and different alcoholic drinks. A maximum sensitivity of 0.13 µg cm-3 Hz-1 was achieved, with a linear frequency response to density. This is the highest liquid density sensitivity obtained for acoustic mode sensors to the best of our knowledge.

Determination of fluoxetine in pharmaceutical and biological samples based on the silver nanoparticle enhanced fluorescence of fluoxetine-terbium complex.

PubMed

Lotfi, Ali; Manzoori, Jamshid L

2016-11-01

In this study, a simple and sensitive spectrofluorimetric method is presented for the determination of fluoxetine based on the enhancing effect of silver nanoparticles (AgNPs) on the terbium-fluoxetine fluorescence emission. The AgNPs were prepared by a simple reduction method and characterized by UV-Vis spectroscopy and transmission electron microscopy. It was indicated that these AgNPs have a remarkable amplifying effect on the terbium-sensitized fluorescence of fluoxetine. The effects of various parameters such as AgNP and Tb 3+ concentration and the pH of the media were investigated. Under obtained optimal conditions, the fluorescence intensity of the terbium-fluoxetine-AgNP system was enhanced linearly by increasing the concentration of fluoxetine in the range of 0.008 to 19 mg/L. The limit of detection (b + 3s) was 8.3 × 10 -4 mg/L. The interference effects of common species found in real samples were also studied. The method had good linearity, recovery, reproducibility and sensitivity, and was satisfactorily applied for the determination of fluoxetine in tablet formulations, human urine and plasma samples. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

A simple ratiometric fluorescent sensor for fructose based on complexation of 10-hydroxybenzo[h]quinoline with boronic acid

NASA Astrophysics Data System (ADS)

Li, Huihui; Yang, Cailing; Zhu, Xinyue; Zhang, Haixia

2017-06-01

A simple ratiometric fluorescent sensor for fructose was presented. It consisted of 10-hydroxybenzo[h]quinoline (HBQ) which showed emission at 572 nm and 3-pyridylboronic acid (PDBA) whose complex with HBQ gave emission at 500 nm. The reaction of fructose with PDBA inhibited the complexation of HBQ with PDBA, resulting in the change of dual-emission intensity ratio. The sensor well quantified fructose in the range of 0.015-2.5 mM with detection limit of 0.005 mM. Besides, this sensor exhibited excellent selectivity and was successfully applied to fructose detection in food. This work provides a simple ratiometric sensing platform for sensitive and selective detection of fructose.

Sensitivity of influenza rapid diagnostic tests to H5N1 and 2009 pandemic H1N1 viruses.

PubMed

Sakai-Tagawa, Yuko; Ozawa, Makoto; Tamura, Daisuke; Le, Mai thi Quynh; Nidom, Chairul A; Sugaya, Norio; Kawaoka, Yoshihiro

2010-08-01

Simple and rapid diagnosis of influenza is useful for making treatment decisions in the clinical setting. Although many influenza rapid diagnostic tests (IRDTs) are available for the detection of seasonal influenza virus infections, their sensitivity for other viruses, such as H5N1 viruses and the recently emerged swine origin pandemic (H1N1) 2009 virus, remains largely unknown. Here, we examined the sensitivity of 20 IRDTs to various influenza virus strains, including H5N1 and 2009 pandemic H1N1 viruses. Our results indicate that the detection sensitivity to swine origin H1N1 viruses varies widely among IRDTs, with some tests lacking sufficient sensitivity to detect the early stages of infection when the virus load is low.

Cellular and Network Mechanisms Underlying Information Processing in a Simple Sensory System

NASA Technical Reports Server (NTRS)

Jacobs, Gwen; Henze, Chris; Biegel, Bryan (Technical Monitor)

2002-01-01

Realistic, biophysically-based compartmental models were constructed of several primary sensory interneurons in the cricket cercal sensory system. A dynamic atlas of the afferent input to these cells was used to set spatio-temporal parameters for the simulated stimulus-dependent synaptic inputs. We examined the roles of dendritic morphology, passive membrane properties, and active conductances on the frequency tuning of the neurons. The sensitivity of narrow-band low pass interneurons could be explained entirely by the electronic structure of the dendritic arbors and the dynamic sensitivity of the SIZ. The dynamic characteristics of interneurons with higher frequency sensitivity required models with voltage-dependent dendritic conductances.

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

PubMed

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

1975-11-01

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

Aptamer-based microspheres for highly sensitive protein detection using fluorescently-labeled DNA nanostructures.

PubMed

Han, Daehoon; Hong, Jinkee; Kim, Hyun Cheol; Sung, Jong Hwan; Lee, Jong Bum

2013-11-01

Many highly sensitive protein detection techniques have been developed and have played an important role in the analysis of proteins. Herein, we report a novel technique that can detect proteins sensitively and effectively using aptamer-based DNA nanostructures. Thrombin was used as a target protein and aptamer was used to capture fluorescent dye-labeled DNA nanobarcodes or thrombin on a microsphere. The captured DNA nanobarcodes were replaced by a thrombin and aptamer interaction. The detection ability of this approach was confirmed by flow cytometry with different concentrations of thrombin. Our detection method has great potential for rapid and simple protein detection with a variety of aptamers.

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

PubMed

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

2010-03-31

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

Effect of noisy stimulation on neurobiological sensitization systems and its role for normal and pathological physiology

NASA Astrophysics Data System (ADS)

Huber, Martin; Braun, Hans; Krieg, J.\\:Urgen-Christian

2004-03-01

Sensitization is discussed as an important phenomenon playing a role in normal physiology but also with respect to the initiation and progression of a variety of neuropsychiatric disorders such as epilepsia, substance-related disorders or recurrent affective disorders. The relevance to understand the dynamics of sensitization phenomena is emphasized by recent findings that even single stimulations can induce longlasting changes in biological systems. To address specific questions associated with the sensitization dynamics, we use a computational approach and develop simple but physiologically-plausible models. In the present study we examine the effect of noisy stimulation on sensitization development in the model. We consider sub- and suprathresold stimulations with varying noise intensities and determine as response measures the (i) absolute number of stimulus-induced sensitzations and (ii) the temporal relsation of stimulus-sensitization coupling. The findings indicate that stochastic effects including stochastic resonance might well contribute to the physiology of sensitization mechanisms under both nomal and pathological conditions.

Women's finger pressure sensitivity at rest and recalled body awareness during partnered sexual activity.

PubMed

Costa, R M; Pestana, José; Costa, David; Wittmann, Marc

2017-07-01

Greater vibrotactile sensitivity has been related to better erectile function in men, and vibrotactile and pressure tactile sensitivity have been related to better sexual function in women. Our previous study found that, for both sexes, greater recalled body awareness during last sexual relation correlated with greater recalled desire and arousal. Using the same sample of that study (68 women and 48 men, recruited in the Lisbon area, Portugal), we tested if greater recalled body awareness during last sexual relation correlates with tactile pressure sensitivity, as assessed by von Frey microfilaments. In simple and partial correlations controlling for social desirability and smoking before last sex, the hypothesis was confirmed for women, but not for men. Greater tactile sensitivity might enhance sexual arousal through greater awareness of the body during sex, and/or more frequent and pleasant body sensations during sex might lead to greater tactile sensitivity in nonsexual situations. Pressure sensitivity might be more closely linked to sexual arousal in women than in men.

Investigation, development and application of optimal output feedback theory. Vol. 4: Measures of eigenvalue/eigenvector sensitivity to system parameters and unmodeled dynamics

NASA Technical Reports Server (NTRS)

Halyo, Nesim

1987-01-01

Some measures of eigenvalue and eigenvector sensitivity applicable to both continuous and discrete linear systems are developed and investigated. An infinite series representation is developed for the eigenvalues and eigenvectors of a system. The coefficients of the series are coupled, but can be obtained recursively using a nonlinear coupled vector difference equation. A new sensitivity measure is developed by considering the effects of unmodeled dynamics. It is shown that the sensitivity is high when any unmodeled eigenvalue is near a modeled eigenvalue. Using a simple example where the sensor dynamics have been neglected, it is shown that high feedback gains produce high eigenvalue/eigenvector sensitivity. The smallest singular value of the return difference is shown not to reflect eigenvalue sensitivity since it increases with the feedback gains. Using an upper bound obtained from the infinite series, a procedure to evaluate whether the sensitivity to parameter variations is within given acceptable bounds is developed and demonstrated by an example.

Application of simple negative feedback model for avalanche photodetectors investigation

NASA Astrophysics Data System (ADS)

Kushpil, V. V.

2009-10-01

A simple negative feedback model based on Miller's formula is used to investigate the properties of Avalanche Photodetectors (APDs). The proposed method can be applied to study classical APD as well as new type of devices, which are operating in the Internal Negative Feedback (INF) regime. The method shows a good sensitivity to technological APD parameters making it possible to use it as a tool to analyse various APD parameters. It also allows better understanding of the APD operation conditions. The simulations and experimental data analysis for different types of APDs are presented.

Detection and recognition of simple spatial forms

NASA Technical Reports Server (NTRS)

Watson, A. B.

1983-01-01

A model of human visual sensitivity to spatial patterns is constructed. The model predicts the visibility and discriminability of arbitrary two-dimensional monochrome images. The image is analyzed by a large array of linear feature sensors, which differ in spatial frequency, phase, orientation, and position in the visual field. All sensors have one octave frequency bandwidths, and increase in size linearly with eccentricity. Sensor responses are processed by an ideal Bayesian classifier, subject to uncertainty. The performance of the model is compared to that of the human observer in detecting and discriminating some simple images.

Simple Electrolyzer Model Development for High-Temperature Electrolysis System Analysis Using Solid Oxide Electrolysis Cell

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

JaeHwa Koh; DuckJoo Yoon; Chang H. Oh

2010-07-01

An electrolyzer model for the analysis of a hydrogen-production system using a solid oxide electrolysis cell (SOEC) has been developed, and the effects for principal parameters have been estimated by sensitivity studies based on the developed model. The main parameters considered are current density, area specific resistance, temperature, pressure, and molar fraction and flow rates in the inlet and outlet. Finally, a simple model for a high-temperature hydrogen-production system using the solid oxide electrolysis cell integrated with very high temperature reactors is estimated.

Benzimidazole derivatives: selective fluorescent chemosensors for the picogram detection of picric acid.

PubMed

Xiong, Jin-Feng; Li, Jian-Xiao; Mo, Guang-Zhen; Huo, Jing-Pei; Liu, Jin-Yan; Chen, Xiao-Yun; Wang, Zhao-Yang

2014-12-05

1,3,5-Tri(1H-benzo[d]imidazol-2-yl)benzene derivatives, as a new kind of fluorescent chemosensor for the detection of nitroaromatic explosives, are designed and synthesized by simple N-hydrocarbylation. Among 16 obtained compounds, compound 4g has the best capability for detection of picric acid (PA), having good selectivity and high sensitivity. The detection of PA with 4g solution-coated paper strips at the picogram level is developed. A simple, portable, and low-cost method is provided for detecting PA in solution and contact mode.

Benchmarking gate-based quantum computers

NASA Astrophysics Data System (ADS)

Michielsen, Kristel; Nocon, Madita; Willsch, Dennis; Jin, Fengping; Lippert, Thomas; De Raedt, Hans

2017-11-01

With the advent of public access to small gate-based quantum processors, it becomes necessary to develop a benchmarking methodology such that independent researchers can validate the operation of these processors. We explore the usefulness of a number of simple quantum circuits as benchmarks for gate-based quantum computing devices and show that circuits performing identity operations are very simple, scalable and sensitive to gate errors and are therefore very well suited for this task. We illustrate the procedure by presenting benchmark results for the IBM Quantum Experience, a cloud-based platform for gate-based quantum computing.

Two smart spectrophotometric methods for the simultaneous estimation of Simvastatin and Ezetimibe in combined dosage form

NASA Astrophysics Data System (ADS)

Magdy, Nancy; Ayad, Miriam F.

2015-02-01

Two simple, accurate, precise, sensitive and economic spectrophotometric methods were developed for the simultaneous determination of Simvastatin and Ezetimibe in fixed dose combination products without prior separation. The first method depends on a new chemometrics-assisted ratio spectra derivative method using moving window polynomial least square fitting method (Savitzky-Golay filters). The second method is based on a simple modification for the ratio subtraction method. The suggested methods were validated according to USP guidelines and can be applied for routine quality control testing.

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

PubMed

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

2015-05-21

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

High-efficiency K-band tracking antenna feed

NASA Technical Reports Server (NTRS)

Beavin, R. L.; Simanyi, A. I.

1975-01-01

Antenna feed features high aperture efficiency of multimode near-field horn and develops tracking signals without conventional monopulse bridge. Feed assembly is relatively simple and very compact. However, feed is sensitive to cross-polarized energy which couples into orthogonal error channel.

Microphone Detects Boiler-Tube Leaks

NASA Technical Reports Server (NTRS)

Parthasarathy, S. P.

1985-01-01

Unit simple, sensitive, rugged, and reliable. Diaphragmless microphone detects leaks from small boiler tubes. Porous plug retains carbon granules in tube while allowing pressure changes to penetrate to granules. Has greater life expectancy than previous controllers and used in variety of hot corrosive atmospheres.

Are You Ready for Y2K?

ERIC Educational Resources Information Center

Day, C. William

1999-01-01

Examines the planning process to identify equipment or systems within an educational facility that could be Y2K sensitive. Discusses developing a contingency plan to prevent operational shutdown. Concluding comments describe a simple Y2K equipment-testing procedure. (GR)

Mimosa-inspired design of a flexible pressure sensor with touch sensitivity.

PubMed

Su, Bin; Gong, Shu; Ma, Zheng; Yap, Lim Wei; Cheng, Wenlong

2015-04-24

A bio-inspired flexible pressure sensor is generated with high sensitivity (50.17 kPa(-1)), quick responding time (<20 ms), and durable stability (negligible loading-unloading signal changes over 10 000 cycles). Notably, the key resource of surface microstructures upon sensor substrates results from the direct molding of natural mimosa leaves, presenting a simple, environment-friendly and easy scale-up fabrication process for these flexible pressure sensors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CdS/CdSe quantum dot shell decorated vertical ZnO nanowire arrays by spin-coating-based SILAR for photoelectrochemical cells and quantum-dot-sensitized solar cells.

PubMed

Zhang, Ran; Luo, Qiu-Ping; Chen, Hong-Yan; Yu, Xiao-Yun; Kuang, Dai-Bin; Su, Cheng-Yong

2012-04-23

A CdS/CdSe composite shell is assembled onto the surface of ZnO nanowire arrays with a simple spin-coating-based successive ionic layer adsorption and reaction method. The as-prepared photoelectrode exhibit a high photocurrent density in photoelectrochemical cells and also generates good power conversion efficiency in quantum-dot-sensitized solar cells. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Absolute and angular efficiencies of a microchannel-plate position-sensitive detector

NASA Technical Reports Server (NTRS)

Gao, R. S.; Gibner, P. S.; Newman, J. H.; Smith, K. A.; Stebbings, R. F.

1984-01-01

This paper presents a characterization of a commercially available position-sensitive detector of energetic ions and neutrals. The detector consists of two microchannel plates followed by a resistive position-encoding anode. The work includes measurement of absolute efficiencies of H(+), He(+), and O(+) ions in the energy range between 250 and 5000 eV, measurement of relative detection efficiencies as a function of particle impact angle, and a simple method for accurate measurement of the time at which a particle strikes the detector.

Potentials for Soil Enzyme as Indicators of Ecological Management

NASA Technical Reports Server (NTRS)

Senwo, Z. N.; Manu, A.; Coleman, T. L.

1997-01-01

Activity measurements of selected soil enzymes (cellulase, glucosidase, amidohydrolase, phosphatase, arylsulfatase) involved in carbon, nitrogen, phosphorus, and sulfur cycling in the biosphere, hold potential as early and sensitive indicators of soil ecological stress and restoration, These measurements are advantageous because the procedures are simple, rapid, and reproducible over time. Enzyme activities are sensitive to short-term changes in soil and kind-use management. Enzyme activities have also been observed to be closely related to soil organic matter proposed as an index of soil quality.

Wireless ultrasound-powered biotelemetry for implants.

PubMed

Towe, Bruce C; Larson, Patrick J; Gulick, Daniel W

2009-01-01

A miniature piezoelectric receiver coupled to a diode is evaluated as a simple device for wireless transmission of bioelectric events to the body surface. The device converts the energy of a surface-applied ultrasound beam to a high frequency carrier current in solution. Bioelectrical currents near the implant modulate the carrier amplitude, and this signal is remotely detected and demodulated to recover the biopotential waveform. This technique achieves millivolt sensitivity in saline tank tests, and further attention to system design is expected to improve sensitivity.

Selective advantage of resistant strains at trace levels of antibiotics: a simple and ultrasensitive color test for detection of antibiotics and genotoxic agents.

PubMed

Liu, Anne; Fong, Amie; Becket, Elinne; Yuan, Jessica; Tamae, Cindy; Medrano, Leah; Maiz, Maria; Wahba, Christine; Lee, Catherine; Lee, Kim; Tran, Katherine P; Yang, Hanjing; Hoffman, Robert M; Salih, Anya; Miller, Jeffrey H

2011-03-01

Many studies have examined the evolution of bacterial mutants that are resistant to specific antibiotics, and many of these focus on concentrations at and above the MIC. Here we ask for the minimum concentration at which existing resistant mutants can outgrow sensitive wild-type strains in competition experiments at antibiotic levels significantly below the MIC, and we define a minimum selective concentration (MSC) in Escherichia coli for two antibiotics, which is near 1/5 of the MIC for ciprofloxacin and 1/20 of the MIC for tetracycline. Because of the prevalence of resistant mutants already in the human microbiome, allowable levels of antibiotics to which we are exposed should be below the MSC. Since this concentration often corresponds to low or trace levels of antibiotics, it is helpful to have simple tests to detect such trace levels. We describe a simple ultrasensitive test for detecting the presence of antibiotics and genotoxic agents. The test is based on the use of chromogenic proteins as color markers and the use of single and multiple mutants of Escherichia coli that have greatly increased sensitivity to either a wide range of antibiotics or specific antibiotics, antibiotic families, and genotoxic agents. This test can detect ciprofloxacin at 1/75 of the MIC.

Rapid, simple and direct detection of Meloidogyne hapla from infected root galls using loop-mediated isothermal amplification combined with FTA technology

PubMed Central

Peng, Huan; Long, Haibo; Huang, Wenkun; Liu, Jing; Cui, Jiangkuan; Kong, Lingan; Hu, Xianqi; Gu, Jianfeng; Peng, Deliang

2017-01-01

The northern root-knot nematode (Meloidogyne hapla) is a damaging nematode that has caused serious economic losses worldwide. In the present study, a sensitive, simple and rapid method was developed for detection of M. hapla in infested plant roots by combining a Flinders Technology Associates (FTA) card with loop-mediated isothermal amplification (LAMP). The specific primers of LAMP were designed based on the distinction of internal transcribed spacer (ITS) sequences between M. hapla and other Meloidogyne spp. The LAMP assay can detect nematode genomic DNA at concentrations low to 1/200 000, which is 100 times more sensitive than conventional PCR. The LAMP was able to highly specifically distinguish M. hapla from other closely related nematode species. Furthermore, the advantages of the FTA-LAMP assay to detect M. hapla were demonstrated by assaying infected root galls that were artificially inoculated. In addition, M. hapla was successfully detected from six of forty-two field samples using FTA-LAMP technology. This study was the first to provide a simple diagnostic assay for M. hapla using the LAMP assay combined with FTA technology. In conclusion, the new FTA-LAMP assay has the potential for diagnosing infestation in the field and managing the pathogen M. hapla. PMID:28368036

Rapid, simple and direct detection of Meloidogyne hapla from infected root galls using loop-mediated isothermal amplification combined with FTA technology.

PubMed

Peng, Huan; Long, Haibo; Huang, Wenkun; Liu, Jing; Cui, Jiangkuan; Kong, Lingan; Hu, Xianqi; Gu, Jianfeng; Peng, Deliang

2017-04-03

The northern root-knot nematode (Meloidogyne hapla) is a damaging nematode that has caused serious economic losses worldwide. In the present study, a sensitive, simple and rapid method was developed for detection of M. hapla in infested plant roots by combining a Flinders Technology Associates (FTA) card with loop-mediated isothermal amplification (LAMP). The specific primers of LAMP were designed based on the distinction of internal transcribed spacer (ITS) sequences between M. hapla and other Meloidogyne spp. The LAMP assay can detect nematode genomic DNA at concentrations low to 1/200 000, which is 100 times more sensitive than conventional PCR. The LAMP was able to highly specifically distinguish M. hapla from other closely related nematode species. Furthermore, the advantages of the FTA-LAMP assay to detect M. hapla were demonstrated by assaying infected root galls that were artificially inoculated. In addition, M. hapla was successfully detected from six of forty-two field samples using FTA-LAMP technology. This study was the first to provide a simple diagnostic assay for M. hapla using the LAMP assay combined with FTA technology. In conclusion, the new FTA-LAMP assay has the potential for diagnosing infestation in the field and managing the pathogen M. hapla.

Selective detection of Co2+ by fluorescent nano probe: Diagnostic approach for analysis of environmental samples and biological activities

NASA Astrophysics Data System (ADS)

Mahajan, Prasad G.; Dige, Nilam C.; Desai, Netaji K.; Patil, Shivajirao R.; Kondalkar, Vijay V.; Hong, Seong-Karp; Lee, Ki Hwan

2018-06-01

Nowadays scientist over the world are engaging to put forth improved methods to detect metal ion in an aqueous medium based on fluorescence studies. A simple, selective and sensitive method was proposed for detection of Co2+ ion using fluorescent organic nanoparticles. We synthesized a fluorescent small molecule viz. 4,4‧-{benzene-1,4-diylbis-[(Z)methylylidenenitrilo]}dibenzoic acid (BMBA) to explore its suitability as sensor for Co2+ ion and biocompatibility in form of nanoparticles. Fluorescence nanoparticles (BMBANPs) prepared by simple reprecipitation method. Aggregation induced enhanced emission of BMBANPs exhibits the narrower particle size of 68 nm and sphere shape morphology. The selective fluorescence quenching was observed by addition of Co2+ and does not affected by presence of other coexisting ion solutions. The photo-physical properties, viz. UV-absorption, fluorescence emission, and lifetime measurements are in support of ligand-metal interaction followed by static fluorescence quenching phenomenon in emission of BMBANPs. Finally, we develop a simple analytical method for selective and sensitive determination of Co2+ ion in environmental samples. The cell culture E. coli, Bacillus sps., and M. tuberculosis H37RV strain in the vicinity of BMBANPs indicates virtuous anti-bacterial and anti-tuberculosis activity which is of additional novel application shown by prepared nanoparticles.

A novel photoelectrochemical biosensor for protein kinase activity assay based on phosphorylated graphite-like carbon nitride.

PubMed

Li, Xue; Zhou, Yunlei; Xu, Yan; Xu, Huijie; Wang, Minghui; Yin, Huanshun; Ai, Shiyun

2016-08-31

Protein kinases are general and significant regulators in the cell signaling pathway, and it is still greatly desired to achieve simple and quick kinase detection. Herein, we develop a simple and sensitive photoelectrochemical strategy for the detection of protein kinase activity based on the bond between phosphorylated peptide and phosphorylated graphite-like carbon nitride (P-g-C3N4) conjugates triggered by Zr(4+) ion coordination. Under optimal conditions, the increased photocurrent is proportional to the protein kinase A (PKA) concentration ranging from 0.05 to 50 U/mL with a detection limit of 0.077 U/mL. Moreover, this photoelectrochemical assay can be also applied to quantitative analysis of kinase inhibition. The results indicated that the IC50 value (inhibitor concentration producing 50% inhibitor) for ellagic acid was 9.1 μM. Moreover, the developed method is further applied to detect PKA activity in real samples, which contains serum from healthy person and gastric cancer patients and breast tissue from healthy person and breast cancer patients. Therefore, the established protocol provides a new and simple tool for assay of kinase activity and its inhibitors with low cost and high sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

IOTA Simple Rules in Differentiating between Benign and Malignant Adnexal Masses by Non-expert Examiners.

PubMed

Tinnangwattana, Dangcheewan; Vichak-Ururote, Linlada; Tontivuthikul, Paponrad; Charoenratana, Cholaros; Lerthiranwong, Thitikarn; Tongsong, Theera

2015-01-01

To evaluate the diagnostic performance of IOTA simple rules in predicting malignant adnexal tumors by non-expert examiners. Five obstetric/gynecologic residents, who had never performed gynecologic ultrasound examination by themselves before, were trained for IOTA simple rules by an experienced examiner. One trained resident performed ultrasound examinations including IOTA simple rules on 100 women, who were scheduled for surgery due to ovarian masses, within 24 hours of surgery. The gold standard diagnosis was based on pathological or operative findings. The five-trained residents performed IOTA simple rules on 30 patients for evaluation of inter-observer variability. A total of 100 patients underwent ultrasound examination for the IOTA simple rules. Of them, IOTA simple rules could be applied in 94 (94%) masses including 71 (71.0%) benign masses and 29 (29.0%) malignant masses. The diagnostic performance of IOTA simple rules showed sensitivity of 89.3% (95%CI, 77.8%; 100.7%), specificity 83.3% (95%CI, 74.3%; 92.3%). Inter-observer variability was analyzed using Cohen's kappa coefficient. Kappa indices of the four pairs of raters are 0.713-0.884 (0.722, 0.827, 0.713, and 0.884). IOTA simple rules have high diagnostic performance in discriminating adnexal masses even when are applied by non-expert sonographers, though a training course may be required. Nevertheless, they should be further tested by a greater number of general practitioners before widely use.

Liquid-fuel valve with precise throttling control

NASA Technical Reports Server (NTRS)

Mcdougal, A. R.; Porter, R. N.; Riebling, R. W.

1971-01-01

Prototype liquid-fuel valve performs on-off and throttling functions in vacuum without component cold-welding or excessive leakage. Valve design enables simple and rapid disassembly and parts replacement and operates with short working stroke, providing maximum throttling sensitivity commensurate with good control.

Sensitive Electroanalysis Using Solid Electrodes.

ERIC Educational Resources Information Center

Wang, Joseph

1982-01-01

A hydrodynamic modulation voltammetry (HMV) experiment involving use of simple hydrodynamic modulation procedures is described. Competing with time/equipment restrictions of most teaching laboratories (stopped-stirring and stopped-flow volumetry), students perform both batch and flow analyses and are introduced to analytical flow systems and the…

Informant-Ethnographers in the Study of Schools

ERIC Educational Resources Information Center

Feer, Michael

1975-01-01

In the context of an anthropology curriculum, public high school students performed as informant-ethnographers of their own social milieu. Using the film and fieldwork techniques, students demonstrated that with training and sensitivity such studies could be more than simple academic exercises. (AUTHOR/NQ)

Estimation of changes in insulation resistance with various design parameters of interdigitated wire loops.

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

Cordaro, Joseph Gabriel; Jones, Reese E.; Neel, Wiley Christopher

2015-09-01

In this report we explore the sensitivities of the insulation resistance between two loops of wire embedded in insulating materials with a simple, approximate model. We discuss limita- tions of the model and ideas for improvements.

Bioassaying for ozone with pollen systems

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

Feder, W.A.

Sensitivity to ozone of pollen germinating in vitro is closely correlated with ozone sensitivity of the pollen parent. Ozone-sensitive and tolerant pollen populations have been identified in tobacco, petunia, and tomato cultivars. The rate of tube elongation can be reversibly slowed or stopped by exposure to low concentrations of ozone. The performance of selected pollen populations can then be used to bioassay ozone in ambient air by introducing the air sample into a growth chamber where ozone-sensitive pollen in growing. Year-round pollen producion can be achieved in the greenhouse. Harvested pollen can be tested, packaged, and transported to user facilitiesmore » without loss of vigor. Pollen populations are inexpensive to produce, respond reliably, and are simple to use as a bioassay for air quality.« less

Photon Counting System for High-Sensitivity Detection of Bioluminescence at Optical Fiber End.

PubMed

Iinuma, Masataka; Kadoya, Yutaka; Kuroda, Akio

2016-01-01

The technique of photon counting is widely used for various fields and also applicable to a high-sensitivity detection of luminescence. Thanks to recent development of single photon detectors with avalanche photodiodes (APDs), the photon counting system with an optical fiber has become powerful for a detection of bioluminescence at an optical fiber end, because it allows us to fully use the merits of compactness, simple operation, highly quantum efficiency of the APD detectors. This optical fiber-based system also has a possibility of improving the sensitivity to a local detection of Adenosine triphosphate (ATP) by high-sensitivity detection of the bioluminescence. In this chapter, we are introducing a basic concept of the optical fiber-based system and explaining how to construct and use this system.

Record of hospitalizations for ambulatory care sensitive conditions: validation of the hospital information system.

PubMed

Rehem, Tania Cristina Morais Santa Barbara; de Oliveira, Maria Regina Fernandes; Ciosak, Suely Itsuko; Egry, Emiko Yoshikawa

2013-01-01

To estimate the sensitivity, specificity and positive and negative predictive values of the Unified Health System's Hospital Information System for the appropriate recording of hospitalizations for ambulatory care-sensitive conditions. The hospital information system records for conditions which are sensitive to ambulatory care, and for those which are not, were considered for analysis, taking the medical records as the gold standard. Through simple random sampling, a sample of 816 medical records was defined and selected by means of a list of random numbers using the Statistical Package for Social Sciences. The sensitivity was 81.89%, specificity was 95.19%, the positive predictive value was 77.61% and the negative predictive value was 96.27%. In the study setting, the Hospital Information System (SIH) was more specific than sensitive, with nearly 20% of care sensitive conditions not detected. There are no validation studies in Brazil of the Hospital Information System records for the hospitalizations which are sensitive to primary health care. These results are relevant when one considers that this system is one of the bases for assessment of the effectiveness of primary health care.

Modulation of the virus-receptor interaction by mutations in the V5 loop of feline immunodeficiency virus (FIV) following in vivo escape from neutralising antibody.

PubMed

Willett, Brian J; Kraase, Martin; Logan, Nicola; McMonagle, Elizabeth L; Samman, Ayman; Hosie, Margaret J

2010-04-26

In the acute phase of infection with feline immunodeficiency virus (FIV), the virus targets activated CD4+ T cells by utilising CD134 (OX40) as a primary attachment receptor and CXCR4 as a co-receptor. The nature of the virus-receptor interaction varies between isolates; strains such as GL8 and CPGammer recognise a "complex" determinant on CD134 formed by cysteine-rich domains (CRDs) 1 and 2 of the molecule while strains such as PPR and B2542 require a more "simple" determinant comprising CRD1 only for infection. These differences in receptor recognition manifest as variations in sensitivity to receptor antagonists. In this study, we ask whether the nature of the virus-receptor interaction evolves in vivo. Following infection with a homogeneous viral population derived from a pathogenic molecular clone, a quasispecies emerged comprising variants with distinct sensitivities to neutralising antibody and displaying evidence of conversion from a "complex" to a "simple" interaction with CD134. Escape from neutralising antibody was mediated primarily by length and sequence polymorphisms in the V5 region of Env, and these alterations in V5 modulated the virus-receptor interaction as indicated by altered sensitivities to antagonism by both anti-CD134 antibody and soluble CD134. The FIV-receptor interaction evolves under the selective pressure of the host humoral immune response, and the V5 loop contributes to the virus-receptor interaction. Our data are consistent with a model whereby viruses with distinct biological properties are present in early versus late infection and with a shift from a "complex" to a "simple" interaction with CD134 with time post-infection.

A fluorescent immunochromatographic strip test using a quantum dot-antibody probe for rapid and quantitative detection of 1-aminohydantoin in edible animal tissues.

PubMed

Le, Tao; Zhang, Zhihao; Wu, Juan; Shi, Haixing; Cao, Xudong

2018-01-01

A rapid, simple, and sensitive fluorescent immunochromatographic strip test (ICST) based on quantum dots (QDs) has been developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. To achieve this, QD-labeled antibody conjugates, which consist of CdSe/ZnS QDs and monoclonal antibodies, were prepared by an activated ester method. Under optimal conditions, with the nitrophenyl derivative of AHD as the target, the ICST had a linear range from 0.1 to 100 ng/mL, with a correlation coefficient of 0.9656 and a 50% inhibitory concentration of 4.51 ng/mL. The limit of detection was 0.14 ng/g, which was below the minimum required performance limit of 1 μg/kg for AHD established by the European Commission. The recoveries for AHD ranged from 81.5% to 108.2%, with coefficients of variation below 13%, based on intraday and interday analysis. Furthermore, for AHD in real samples, the ICST showed high reliability and high correlation with liquid chromatography-tandem mass spectrometry (correlation coefficient of 0.9916). To the best of our knowledge, this is the first report of a novel and sensitive method based on a fluorescent ICST to detect AHD below the minimum required performance limit. The ICST demonstrated high reliability, and could be ideally suited for rapid, simple, and on-site screening of AHD contamination in animal tissues. Graphical abstract A rapid, simple, and sensitive fluorescent immunochromatographic strip test that is based on quantum dots was developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. 2-NBA 2-nitrobenzaldehyde, NP nitrophenyl.

Use of Malachite Green-Loop Mediated Isothermal Amplification for Detection of Plasmodium spp. Parasites

PubMed Central

Lucchi, Naomi W.; Ljolje, Dragan; Silva-Flannery, Luciana; Udhayakumar, Venkatachalam

2016-01-01

Malaria elimination efforts are hampered by the lack of sensitive tools to detect infections with low-level parasitemia, usually below the threshold of standard diagnostic methods, microscopy and rapid diagnostic tests. Isothermal nucleic acid amplification assays such as the loop-mediated isothermal amplification (LAMP), are well suited for field use as they do not require thermal cyclers to run the test. However, the use of specialized equipment, as described by many groups, reduces the versatility of the LAMP technique as a simple tool for use in endemic countries. In this study, the use of the malachite green (MG) dye, as a visual endpoint readout, together with a simple mini heat block was evaluated for the detection of malaria parasites. The assay was performed for 1 hour at 63°C and the results scored by 3 independent human readers. The limit of detection of the assay was determined using well-quantified Plasmodium spp. infected reference samples and its utility in testing clinical samples was determined using 190 pre-treatment specimens submitted for reference diagnosis of imported malaria in the United States. Use of a simplified boil and spin methods of DNA extraction from whole blood and filter paper was also investigated. We demonstrate the accurate and sensitive detection of malaria parasites using this assay with a detection limit ranging between 1–8 parasites/μL, supporting its applicability for the detection of infections with low parasite burden. This assay is compatible with the use of a simple boil and spin sample preparation method from both whole blood and filter papers without a loss of sensitivity. The MG-LAMP assay described here has great potential to extend the reach of molecular tools to settings where they are needed. PMID:26967908

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

PubMed

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

2013-05-01

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

Stochastic sensitivity measure for mistuned high-performance turbines

NASA Technical Reports Server (NTRS)

Murthy, Durbha V.; Pierre, Christophe

1992-01-01

A stochastic measure of sensitivity is developed in order to predict the effects of small random blade mistuning on the dynamic aeroelastic response of turbomachinery blade assemblies. This sensitivity measure is based solely on the nominal system design (i.e., on tuned system information), which makes it extremely easy and inexpensive to calculate. The measure has the potential to become a valuable design tool that will enable designers to evaluate mistuning effects at a preliminary design stage and thus assess the need for a full mistuned rotor analysis. The predictive capability of the sensitivity measure is illustrated by examining the effects of mistuning on the aeroelastic modes of the first stage of the oxidizer turbopump in the Space Shuttle Main Engine. Results from a full analysis mistuned systems confirm that the simple stochastic sensitivity measure predicts consistently the drastic changes due to misturning and the localization of aeroelastic vibration to a few blades.

Approaches to Study Light Effects on Brassinosteroid Sensitivity.

PubMed

Paulišić, Sandi; Molina-Contreras, Maria José; Roig-Villanova, Irma; Martínez-García, Jaime F

2017-01-01

Light perception and hormone signaling in plants are likely connected at multiple points. Light conditions, perceived by photoreceptors, control plant responses by altering hormone concentration, tissue sensitivity, or a combination of both. Whereas it is relatively straightforward to assess the light effects on hormone levels, hormone sensitivity is subjected to interpretation. In Arabidopsis thaliana seedlings, hypocotyl length is strongly affected by light conditions. As hypocotyl elongation also depends on brassinosteroids (BRs), assaying this response provides a valuable and easy way to measure the responsiveness of seedlings to BRs and the impact of light. We describe a simple protocol to evaluate the responsiveness of hypocotyls to commercial BRs and/or BR inhibitors under a range of light conditions. These assays can be used to establish whether light affects BR sensitivity or whether BRs affect light sensitivity. Overall, our protocol can be easily applied for deetiolation (under polychromatic or monochromatic light) and simulated shade treatments combined with BR treatments.

Low-temperature sensitivity periodically tapered photonic crystal-fiber-based refractometer.

PubMed

Wang, Pengfei; Bo, Lin; Guan, Chunying; Semenova, Yuliya; Wu, Qiang; Brambilla, Gilberto; Farrell, Gerald

2013-10-01

In this Letter, an all-fiber refractometer with a simple configuration of periodical tapers on a photonic crystal fiber (PCF) is proposed and investigated experimentally. The proposed fiber refractive index (RI) sensor consists of a PCF sandwiched between two standard single-mode fibers, with tapers periodically fabricated along the PCF using a CO(2) laser beam focused by a ZnSe cylindrical lens. The proposed fiber sensor can be used for RI sensing by measuring the wavelength shift of the multimode interference dip over the transmission spectrum. An average sensitivity of 222 nm/RIU has been experimentally achieved over a RI range from 1.33 to 1.38. The proposed refractometer is also significantly less sensitive to temperature, and an experimental demonstration of this reduced sensitivity is presented. The proposed RI sensor benefits from simplicity and low-cost and achieves a competitive sensitivity compared with other existing fiber-optic sensors.

Near instrument-free, simple molecular device for rapid detection of herpes simplex viruses.

PubMed

Lemieux, Bertrand; Li, Ying; Kong, Huimin; Tang, Yi-Wei

2012-06-01

The first near instrument-free, inexpensive and simple molecular diagnostic device (IsoAmp HSV, BioHelix Corp., MA, USA) recently received US FDA clearance for use in the detection of herpes simplex viruses (HSV) in genital and oral lesion specimens. The IsoAmp HSV assay uses isothermal helicase-dependent amplification in combination with a disposable, hermetically-sealed, vertical-flow strip identification. The IsoAmp HSV assay has a total test-to-result time of less than 1.5 h by omitting the time-consuming nucleic acid extraction. The diagnostic sensitivity and specificity are comparable to PCR and are superior to culture-based methods. The near instrument-free, rapid and simple characteristics of the IsoAmp HSV assay make it potentially suitable for point-of-care testing.

Estimation of Somatomedin-C Levels in Normals and Patients with Pituitary Disease by Radioimmunoassay

PubMed Central

Furlanetto, Richard W.; Underwood, Louis E.; Van Wyk, Judson J.; D'Ercole, A. Joseph

1977-01-01

The development of a radioimmunoassay for somatomedin-C has for the first time made it possible to discriminate between serum concentrations of a single peptide or closely related group of peptides and the net somatomedin activity measured by less specific bioassay and radioreceptor techniques. Antibodies to human somatomedin-C were raised in rabbits using a somatomedin-C ovalbumin complex as the antigen. A variety of peptide hormones at concentrations up to 1 μM are not recognized by the antibody. Insulin at concentrations >0.1 μM cross reacts in a non-parallel fashion; purified somatomedin-A is only 3% as active as somatomedin-C; and radiolabeled cloned rat liver multiplication stimulating activity does not bind to the antibody. Immunoreactive somatomedin-C can also be quantitated in the sera of a variety of subhuman species. Unusual assay kinetics, which are manifest when reactants are incubated under classic “equilibrium” assay conditions, appear to result from the failure of 125I-somatomedin-C to readily equilibrate with the somatomedin-C serum binding protein complex. It is, therefore, necessary to use nonequilibrium assay conditions to quantitate somatomedin-C in serum. With this assay it is possible to detect somatomedin-C in normal subjects using as little as 0.25 μl of unextracted serum. Serum somatomedin-C concentrations in normal subjects were lowest in cord blood and rose rapidly during the first 4 yr of life to near adult levels. In 23 normal adult volunteers, the mean serum somatomedin-C concentration was 1.50±0.10 U/ml (SEM) when compared to a pooled adult serum standard. 19 children with hypopituitary dwarfism had concentrations below 0.20 U/ml. 17 of these were below 0.1 U/ml, the lower limit of sensitivity of the assay. The mean concentration in 14 adults with active acromegaly was 6.28±0.37 U/ml (SEM), five times greater than the normal volunteers. Significant increases in serum somatomedin-C concentrations were observed in 8 of 10 hypopituitary children within 72 h after the parenteral administration of human growth hormone. Three patients with Cushing's disease had elevated serum somatomedin-C concentrations (2.61±0.14 U/ml [SEM]). Three patients with hyperprolactinemia had normal concentrations (1.74±0.11 U/ml [SEM]). The important new discovery brought to light by quantitation of immunoassayable somatomedin in patient sera is that all previously used assays detect, in addition to somatomedin-C, serum substances that are not under as stringent growth hormone control. PMID:893668

Receptors for VIP and PACAP in guinea pig cerebral cortex: effects on cyclic AMP synthesis and characterization by 125I-VIP binding.

PubMed

Zawilska, Jolanta B; Dejda, Agnieszka; Niewiadomski, Pawel; Gozes, Illana; Nowak, Jerzy Z

2005-01-01

Receptors for vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) in guinea pig cerebral cortex were characterized by (1) radioreceptor binding of 125I-labeled VIP (human/rat/porcine), and (2) cyclic AMP (cAMP) formation. Saturation analysis of 125I-VIP binding to membranes of guinea pig cerebral cortex resulted in a linear Scatchard plot, suggesting the presence of a single class of high-affinity receptor-binding sites, with a Kd of 0.63 nM and a B(max) of 77 fmol/mg protein. Various peptides from the PACAP/VIP/secretin family displaced the specific binding of 125I-VIP to guinea pig cerebrum with the relative rank order of potency: chicken VIP (cVIP) > or = PACAP38 approximately PACAP27 approximately guinea pig VIP (gpVIP) > or = mammalian (human/rat/porcine) VIP (mVIP) > peptide histidine-methionine (PHM) > peptide histidine-isoleucine (PHI) > secretin. Analysis of the competition curves revealed displacement of 125I-VIP from high- and lower-affinity binding sites, with IC50 values in the picomolar and the nanomolar range, respectively. About 70% of the specific 125I-VIP-binding sites in guinea pig cerebral cortex were sensitive to Gpp(NH)p, a nonhydrolyzable analog of GTP. Pituitary adenylate cyclase-activating polypeptide 38 (PACAP38), PACAP27, cVIP, gpVIP, mVIP, PHM, and PHI stimulated cAMP production in [3H]adenine-prelabeled slices of guinea pig cerebral cortex in a concentration-dependent manner. Of the tested peptides, the most effective were PACAP38 and PACAP27, which at a 1 microM concentration produced a 17- to 19-fold rise in cAMP synthesis, increasing the nucleotide production to approx 11% conversion above the control value. The three forms of VIP (cVIP, mVIP, and gpVIP) at the highest concentration used, i.e., 3 microM, produced net increases in cAMP production in the range of 8-9% conversion, whereas 5 microM PHM and PHI, by, respectively, 6.7% and 4.9% conversion. It is concluded that cerebral cortex of guinea pig contains VPAC- type receptors positively linked to cAMP formation. In addition, the observed stronger action of PACAP (both PACAP38 and PACAP27), when compared to any form of VIP, on cAMP production in this tissue, suggests its interaction with both PAC1 and VPAC receptors.

Simultaneous determination of indoor ammonia pollution and its biological metabolite in the human body with a recyclable nanocrystalline lanthanide-functionalized MOF

NASA Astrophysics Data System (ADS)

Hao, Ji-Na; Yan, Bing

2016-01-01

A Eu3+ post-functionalized metal-organic framework of nanosized Ga(OH)bpydc(Eu3+@Ga(OH)bpydc, 1a) with intense luminescence is synthesized and characterized. Luminescence measurements reveal that 1a can detect ammonia gas selectively and sensitively among various indoor air pollutants. 1a can simultaneously determine a biological ammonia metabolite (urinary urea) in the human body, which is a rare example of a luminescent sensor that can monitor pollutants in the environment and also detect their biological markers. Furthermore, 1a exhibits appealing features including high selectivity and sensitivity, fast response, simple and quick regeneration, and excellent recyclability.A Eu3+ post-functionalized metal-organic framework of nanosized Ga(OH)bpydc(Eu3+@Ga(OH)bpydc, 1a) with intense luminescence is synthesized and characterized. Luminescence measurements reveal that 1a can detect ammonia gas selectively and sensitively among various indoor air pollutants. 1a can simultaneously determine a biological ammonia metabolite (urinary urea) in the human body, which is a rare example of a luminescent sensor that can monitor pollutants in the environment and also detect their biological markers. Furthermore, 1a exhibits appealing features including high selectivity and sensitivity, fast response, simple and quick regeneration, and excellent recyclability. Electronic supplementary information (ESI) available: Experimental section; XPS spectra; N2 adsorption-desorption isotherms; ICP data; SEM image; PXRD patterns and other luminescence data. See DOI: 10.1039/c5nr06066d

A flower-like nickel oxide nanostructure: synthesis and application for choline sensing.

PubMed

Sattarahmady, N; Heli, H; Dehdari Vais, R

2014-02-01

Flower-like nickel oxide nanostructure was synthesized by a simple desolvation method. The nanostructure was then employed as the modifier of a carbon paste electrode to fabricate a choline sensor. The mechanism and kinetics of the electrocatalytic oxidation of choline on the modified electrode surface were studied by cyclic voltammetry, steady-state polarization curve, and chronoamperometry. The catalytic rate constant and the charge transfer coefficient of the choline electrooxidation process by an active nickel species, and the diffusion coefficient of choline were reported. An amperometric method was developed for determination of choline with a sensitivity of 60.5 mA mol(-1)Lcm(-2) and a limit of detection of 25.4 μmol L(-1). The sensor had the advantages of high electrocatalytic activity and sensitivity, and long-term stability toward choline, with a simple fabrication method without complications of immobilization steps and using any enzyme or reagent. © 2013 Published by Elsevier B.V.

Indirect glyphosate detection based on ninhydrin reaction and surface-enhanced Raman scattering spectroscopy

NASA Astrophysics Data System (ADS)

Xu, Meng-Lei; Gao, Yu; Li, Yali; Li, Xueliang; Zhang, Huanjie; Han, Xiao Xia; Zhao, Bing; Su, Liang

2018-05-01

Glyphosate is one of the most commonly-used and non-selective herbicides in agriculture, which may directly pollute the environment and threaten human health. A simple and effective approach to assessment of its damage to the natural environment is thus quite necessary. However, traditional chromatography-based detection methods usually suffer from complex pretreatment procedures. Herein, we propose a simple and sensitive method for the determination of glyphosate by combining ninhydrin reaction and surface-enhanced Raman scattering (SERS) spectroscopy. The product (purple color dye, PD) of the ninhydrin reaction is found to SERS-active and directly correlate with the glyphosate concentration. The limit of detection of the proposed method for glyphosate is as low as 1.43 × 10- 8 mol·L- 1 with a relatively wider linear concentration range (1.0 × 10- 7-1.0 × 10- 4 mol·L- 1), which demonstrates its great potential in rapid, highly sensitive concentration determination of glyphosate in practical applications for safety assessment of food and environment.

Universal sensitivity of speckle intensity correlations to wavefront change in light diffusers

PubMed Central

Kim, KyungDuk; Yu, Hyeonseung; Lee, KyeoReh; Park, YongKeun

2017-01-01

Here, we present a concept based on the realization that a complex medium can be used as a simple interferometer. Changes in the wavefront of an incident coherent beam can be retrieved by analyzing changes in speckle patterns when the beam passes through a light diffuser. We demonstrate that the spatial intensity correlations of the speckle patterns are independent of the light diffusers, and are solely determined by the phase changes of an incident beam. With numerical simulations using the random matrix theory, and an experimental pressure-driven wavefront-deforming setup using a microfluidic channel, we theoretically and experimentally confirm the universal sensitivity of speckle intensity correlations, which is attributed to the conservation of optical field correlation despite multiple light scattering. This work demonstrates that a light diffuser works as a simple interferometer, and presents opportunities to retrieve phase information of optical fields with a compact scattering layer in various applications in metrology, analytical chemistry, and biomedicine. PMID:28322268

ZnO nanorod arrays and direct wire bonding on GaN surfaces for rapid fabrication of antireflective, high-temperature ultraviolet sensors

NASA Astrophysics Data System (ADS)

So, Hongyun; Senesky, Debbie G.

2016-11-01

Rapid, cost-effective, and simple fabrication/packaging of microscale gallium nitride (GaN) ultraviolet (UV) sensors are demonstrated using zinc oxide nanorod arrays (ZnO NRAs) as an antireflective layer and direct bonding of aluminum wires to the GaN surface. The presence of the ZnO NRAs on the GaN surface significantly reduced the reflectance to less than 1% in the UV and 4% in the visible light region. As a result, the devices fabricated with ZnO NRAs and mechanically stable aluminum bonding wires (pull strength of 3-5 gf) showed higher sensitivity (136.3% at room temperature and 148.2% increase at 250 °C) when compared with devices with bare (uncoated) GaN surfaces. In addition, the devices demonstrated reliable operation at high temperatures up to 300 °C, supporting the feasibility of simple and cost-effective UV sensors operating with higher sensitivity in high-temperature conditions, such as in combustion, downhole, and space exploration applications.

Silicon nanowires: where mechanics and optics meet at the nanoscale.

PubMed

Ramos, Daniel; Gil-Santos, Eduardo; Malvar, Oscar; Llorens, Jose M; Pini, Valerio; San Paulo, Alvaro; Calleja, Montserrat; Tamayo, Javier

2013-12-06

Mechanical transducers based on nanowires promise revolutionary advances in biological sensing and force microscopy/spectroscopy. A crucial step is the development of simple and non-invasive techniques able to detect displacements with subpicometer sensitivity per unit bandwidth. Here, we design suspended tapered silicon nanowires supporting a range of optical resonances that confine and efficiently scatter light in the visible range. Then, we develop an optical method for efficiently coupling the evanescent field to the regular interference pattern generated by an incoming laser beam and the reflected beam from the substrate underneath the nanowire. This optomechanical coupling is here applied to measure the displacement of 50 nm wide nanowires with sensitivity on the verge of 1 fm/Hz(1/2) at room temperature with a simple laser interferometry set-up. This method opens the door to the measurement of the Brownian motion of ultrashort nanowires for the detection of single biomolecular recognition events in liquids, and single molecule spectroscopy in vacuum.

Continuous liquid level detection based on two parallel plastic optical fibers in a helical structure

NASA Astrophysics Data System (ADS)

Zhang, Yingzi; Hou, Yulong; Zhang, Yanjun; Hu, Yanjun; Zhang, Liang; Gao, Xiaolong; Zhang, Huixin; Liu, Wenyi

2018-02-01

A simple and low-cost continuous liquid-level sensor based on two parallel plastic optical fibers (POFs) in a helical structure is presented. The change in the liquid level is determined by measuring the side-coupling power in the passive fiber. The side-coupling ratio is increased by just filling the gap between the two POFs with ultraviolet-curable optical cement, making the proposed sensor competitive. The experimental results show that the side-coupling power declines as the liquid level rises. The sensitivity and the measurement range are flexible and affected by the geometric parameters of the helical structure. A higher sensitivity of 0.0208 μW/mm is acquired for a smaller curvature radius of 5 mm, and the measurement range can be expanded to 120 mm by enlarging the screw pitch to 40 mm. In addition, the reversibility and temperature dependence are studied. The proposed sensor is a cost-effective solution offering the advantages of a simple fabrication process, good reversibility, and compensable temperature dependence.

Sol-gel spin coated well adhered MoO3 thin films as an alternative counter electrode for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Mutta, Geeta R.; Popuri, Srinivasa R.; Wilson, John I. B.; Bennett, Nick S.

2016-11-01

In this work, we aim to develop a viable, inexpensive and non-toxic material for counter electrodes in dye sensitized solar cells (DSSCs). We employed an ultra-simple synthesis process to deposit MoO3 thin films at low temperature by sol-gel spin coating technique. These MoO3 films showed good transparency. It is predicted that there will be 150 times reduction of precursors cost by realizing MoO3 thin films as a counter electrode in DSSCs compared to commercial Pt. We achieved a device efficiency of about 20 times higher than that of the previous reported values. In summary we develop a simple low cost preparation of MoO3 films with an easily scaled up process along with good device efficiency. This work encourages the development of novel and relatively new materials and paves the way for massive reduction of industrial costs which is a prime step for commercialization of DSSCs.

Living cell dry mass measurement using quantitative phase imaging with quadriwave lateral shearing interferometry: an accuracy and sensitivity discussion.

PubMed

Aknoun, Sherazade; Savatier, Julien; Bon, Pierre; Galland, Frédéric; Abdeladim, Lamiae; Wattellier, Benoit; Monneret, Serge

2015-01-01

Single-cell dry mass measurement is used in biology to follow cell cycle, to address effects of drugs, or to investigate cell metabolism. Quantitative phase imaging technique with quadriwave lateral shearing interferometry (QWLSI) allows measuring cell dry mass. The technique is very simple to set up, as it is integrated in a camera-like instrument. It simply plugs onto a standard microscope and uses a white light illumination source. Its working principle is first explained, from image acquisition to automated segmentation algorithm and dry mass quantification. Metrology of the whole process, including its sensitivity, repeatability, reliability, sources of error, over different kinds of samples and under different experimental conditions, is developed. We show that there is no influence of magnification or spatial light coherence on dry mass measurement; effect of defocus is more critical but can be calibrated. As a consequence, QWLSI is a well-suited technique for fast, simple, and reliable cell dry mass study, especially for live cells.

Label-free immunosensor based on gold nanoparticle silver enhancement.

PubMed

Yang, Minghui; Wang, Cunchang

2009-02-01

A label-free immunosensor for the sensitive detection of human immunoglobulin G (IgG) was prepared based on gold nanoparticle-silver enhancement detection with a simple charge-coupled device (CCD) detector. The gold nanoparticles, which were used as nuclei for the deposit of metallic silver and also for the adsorption of antibodies, were immobilized into wells of a 9-well chip. With the addition of silver enhancement buffer, metallic silver will deposit onto gold nanoparticles, causing darkness that can be optically measured by the CCD camera and quantified using ImageJ software. When antibody was immobilized onto the gold nanoparticles and antigen was captured, the formed immunocomplex resulted in a decrease of the darkness and the intensity of the darkness was in line with IgG concentrations from 0.05 to 10 ng/ml. The CCD detector is simple and portable, and the reported method has many desirable merits such as sensitivity and accuracy, making it a promising technique for protein detection.

Smart electronic yarns and wearable fabrics for human biomonitoring made by carbon nanotube coating with polyelectrolytes.

PubMed

Shim, Bong Sup; Chen, Wei; Doty, Chris; Xu, Chuanlai; Kotov, Nicholas A

2008-12-01

The idea of electronic yarns and textiles has appeared for quite some time, but their properties often do not meet practical expectations. In addition to chemicallmechanical durability and high electrical conductivity, important materials qualifications include weavablity, wearability, light weight, and "smart" functionalities. Here we demonstrate a simple process of transforming general commodity cotton threads into intelligent e-textiles using a polyelectrolyte-based coating with carbon nanotubes (CNTs). Efficient charge transport through the network of nanotubes (20 omega/cm) and the possibility to engineer tunneling junctions make them promising materials for many high-knowledge-content garments. Along with integrated humidity sensing, we demonstrate that CNT-cotton threads can be used to detect albumin, the key protein of blood, with high sensitivity and selectivity. Notwithstanding future challenges, these proof-of-concept demonstrations provide a direct pathway for the application of these materials as wearable biomonitoring and telemedicine sensors, which are simple, sensitive, selective, and versatile.

Simple and sensitive HPLC method with fluorescence detection for the measurement of ibuprofen in rat plasma: application to a long-lasting dosage form.

PubMed

Hassan, Ahmed Sheikh; Sapin, Anne; Ubrich, Nathalie; Maincent, Philippe; Bolzan, Claire; Leroy, Pierre

2008-10-01

A simple and sensitive high-performance liquid chromatography (HPLC) assay applied to the measurement of ibuprofen in rat plasma has been developed. Two parameters have been investigated to improve ibuprofen detectability using fluorescence detection: variation of mobile phase pH and the use of beta-cyclodextrin (beta-CD). Increasing the pH value from 2.5 to 6.5 and adding 5 mM beta-CD enhanced the fluorescence signal (lambda(exc) = 224 nm; lambda(em) = 290 nm) by 2.5 and 1.3-fold, respectively, when using standards. In the case of plasma samples, only pH variation significantly lowered detection and quantification limits, down to 10 and 35 ng/mL, respectively. Full selectivity was obtained with a single step for plasma treatment, that is, protein precipitation with acidified acetonitrile. The validated method was applied to a pharmacokinetic study of ibuprofen encapsulated in microspheres and subcutaneously administered to rats.

Utilizing a CdTe quantum dots-enzyme hybrid system for the determination of both phenolic compounds and hydrogen peroxide.

PubMed

Yuan, Jipei; Guo, Weiwei; Wang, Erkang

2008-02-15

In this paper, we attempt to construct a simple and sensitive detection method for both phenolic compounds and hydrogen peroxide, with the successful combination of the unique property of quantum dots and the specificity of enzymatic reactions. In the presence of H2O2 and horseradish peroxidase, phenolic compounds can quench quantum dots' photoluminescence efficiently, and the extent of quenching is severalfold to more than 100-fold increase. Quinone intermediates produced from the enzymatic catalyzed oxidation of phenolic compounds were believed to play the main role in the photoluminescence quenching. Using a quantum dots-enzyme system, the detection limits for phenolic compounds and hydrogen peroxide were detected to be approximately 10(-7) mol L(-1). The coupling of efficient quenching of quantum dot photoluminescence by quinone and the effective enzymatic reactions make this a simple and sensitive method for phenolic compound detection and great potential in the development of H2O2 biosensors for various analytes.

Application of sulphanilamides disazo dyes with Tropaeolin O for simple, rapid and sensitive spectrophotometric assay of medicines.

PubMed

Boiko, Maria; Vrublevska, Teodoziya; Korkuna, Olha; Teslyar, Grigory

2011-07-01

A rapid, simple and sensitive spectrophotometric method for the determination of some sulphanilamides is described. The method is based on the formation of blue coloured disazo dyes by the diazotization of sulphonamides viz. sulphanilamide (SA), sulphamerazine (SMR), sulphamethazine (SMZ), sulphadimethoxine (SDM), sulphamethoxazole (SMX), sulphadiazine (SDA), sulfathiazole (STZ), sulphaguanidine (SGN), sulphamonomethoxine (SMM), sulphamethoxypyridazine (SMP) in 0.5M hydrochloric acid media at ice bath followed by the azocoupling reaction with acid monoazo dye Tropaeolin O (TrO) at pH=10.5. Formed products are stable for 10h at room temperature. Effective molar absorptivities at absorbance maxima 595nm for disazo dyes were ∼10(4)M(-1)cm(-1). Stoichiometric ratios of the components of disazo dyes were determined by means of mole ratio and continuous variations methods. Linear ranges for sulphanilamides determination were 0.4-14.0μgml(-1). The methods were successfully approved at suphanilamides determination in model solutions and commercial pharmaceutical preparations. Copyright © 2011 Elsevier B.V. All rights reserved.

Sensitivity studies and a simple ozone perturbation experiment with a truncated two-dimensional model of the stratosphere

NASA Technical Reports Server (NTRS)

Stordal, Frode; Garcia, Rolando R.

1987-01-01

The 1-1/2-D model of Holton (1986), which is actually a highly truncated two-dimensional model, describes latitudinal variations of tracer mixing ratios in terms of their projections onto second-order Legendre polynomials. The present study extends the work of Holton by including tracers with photochemical production in the stratosphere (O3 and NOy). It also includes latitudinal variations in the photochemical sources and sinks, improving slightly the calculated global mean profiles for the long-lived tracers studied by Holton and improving substantially the latitudinal behavior of ozone. Sensitivity tests of the dynamical parameters in the model are performed, showing that the response of the model to changes in vertical residual meridional winds and horizontal diffusion coefficients is similar to that of a full two-dimensional model. A simple ozone perturbation experiment shows the model's ability to reproduce large-scale latitudinal variations in total ozone column depletions as well as ozone changes in the chemically controlled upper stratosphere.

Photonic crystal fiber long-period gratings for structural monitoring and chemical sensing

NASA Astrophysics Data System (ADS)

Tang, Jaw-Luen; Wang, Jian-Neng

2008-03-01

We present a simple, low-cost, temperature- and strain-insensitive long-period gratings (LPGs) written in photonic crystal fibers (PCFs) that can be used as sensitive chemical solution sensors or bend sensors for a variety of industrial applications, including civil engineering, aircraft, chemistry, food industry, and biosensing. Three different configurations of PCFs have been used for this study, including a polarization maintaining PCF, a large mode area PCF and an endlessly single mode PCF. These LPGs have been characterized for their sensitivity to temperature, strain, bending, and surrounding refractive index. Transmission spectra of the LPGs were found to exhibit negligible temperature and strain sensitivities, whereas possessing usable sensitivity to refractive index and bending. This type of PCF sensor could in principle be designed for optimum sensitivity to desired measurand(s), while minimizing or removing undesirable cross-sensitivities. The unique sensing features of PCFs are particularly suited for a wide variety of applications in smart structures, embedded materials, telecommunications and sensor systems.

Sensory Optimization by Stochastic Tuning

PubMed Central

Jurica, Peter; Gepshtein, Sergei; Tyukin, Ivan; van Leeuwen, Cees

2013-01-01

Individually, visual neurons are each selective for several aspects of stimulation, such as stimulus location, frequency content, and speed. Collectively, the neurons implement the visual system’s preferential sensitivity to some stimuli over others, manifested in behavioral sensitivity functions. We ask how the individual neurons are coordinated to optimize visual sensitivity. We model synaptic plasticity in a generic neural circuit, and find that stochastic changes in strengths of synaptic connections entail fluctuations in parameters of neural receptive fields. The fluctuations correlate with uncertainty of sensory measurement in individual neurons: the higher the uncertainty the larger the amplitude of fluctuation. We show that this simple relationship is sufficient for the stochastic fluctuations to steer sensitivities of neurons toward a characteristic distribution, from which follows a sensitivity function observed in human psychophysics, and which is predicted by a theory of optimal allocation of receptive fields. The optimal allocation arises in our simulations without supervision or feedback about system performance and independently of coupling between neurons, making the system highly adaptive and sensitive to prevailing stimulation. PMID:24219849

Demonstration of polarization-insensitive spatial light modulation using a single polarization-sensitive spatial light modulator.

PubMed

Liu, Jun; Wang, Jian

2015-07-06

We present a simple configuration incorporating a single polarization-sensitive phase-only liquid crystal spatial light modulator (LC-SLM) to facilitate polarization-insensitive spatial light modulation. The polarization-insensitive configuration is formed by a polarization beam splitter (PBS), a polarization-sensitive phase-only LC-SLM, a half-wave plate (HWP), and a mirror in a loop structure. We experimentally demonstrate polarization-insensitive spatial light modulations for incident linearly polarized beams with different polarization states and polarization-multiplexed beams. Polarization-insensitive spatial light modulations generating orbital angular momentum (OAM) beams are demonstrated in the experiment. The designed polarization-insensitive configuration may find promising applications in spatial light modulations accommodating diverse incident polarizations.

Extremely high frequency sensitivity in a 'simple' ear.

PubMed

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

2013-08-23

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.

Scaling in sensitivity analysis

USGS Publications Warehouse

Link, W.A.; Doherty, P.F.

2002-01-01

Population matrix models allow sets of demographic parameters to be summarized by a single value 8, the finite rate of population increase. The consequences of change in individual demographic parameters are naturally measured by the corresponding changes in 8; sensitivity analyses compare demographic parameters on the basis of these changes. These comparisons are complicated by issues of scale. Elasticity analysis attempts to deal with issues of scale by comparing the effects of proportional changes in demographic parameters, but leads to inconsistencies in evaluating demographic rates. We discuss this and other problems of scaling in sensitivity analysis, and suggest a simple criterion for choosing appropriate scales. We apply our suggestions to data for the killer whale, Orcinus orca.

Wide-Field Imaging of Single-Nanoparticle Extinction with Sub-nm2 Sensitivity

NASA Astrophysics Data System (ADS)

Payne, Lukas M.; Langbein, Wolfgang; Borri, Paola

2018-03-01

We report on a highly sensitive wide-field imaging technique for quantitative measurement of the optical extinction cross section σext of single nanoparticles. The technique is simple and high speed, and it enables the simultaneous acquisition of hundreds of nanoparticles for statistical analysis. Using rapid referencing, fast acquisition, and a deconvolution analysis, a shot-noise-limited sensitivity down to 0.4 nm2 is achieved. Measurements on a set of individual gold nanoparticles of 5 nm diameter using this method yield σext=(10.0 ±3.1 ) nm2, which is consistent with theoretical expectations and well above the background fluctuations of 0.9 nm2 .

A cockspur for the DSS cells: Erythrina crista-galli sensitizers

NASA Astrophysics Data System (ADS)

Enciso, Paula; Decoppet, Jean-David; Grätzel, Michael; Wörner, Michael; Cabrerizo, Franco M.; Cerdá, María Fernanda

2017-04-01

Dye sensitized solar cells were assembled employing a mixture of anthocyanins extracted from red ceibo's flowers. At the literature different extraction procedures are reported to extract anthocyanins from natural products and sensitize the cells. In order to compare them, different methods were followed to set the cells under the same conditions. Assembled cells showed very interesting conversion efficiency values, reaching a 0.73% value for extracts purified using C18 column, in open cells under illumination using a solar light simulator, 1 sun, 1.5 AM. Data reported herein prove that anthocyanins obtained from ceibo's flower, after simple further purification, might represent an excellent, cheap and clean alternative for the development of DSS cells.

Accurate antemortem diagnosis of equine protozoal myeloencephalitis (EPM) based on detecting intrathecal antibodies against Sarcocystis neurona using the SnSAG2 and SnSAG4/3 ELISAs.

PubMed

Reed, S M; Howe, D K; Morrow, J K; Graves, A; Yeargan, M R; Johnson, A L; MacKay, R J; Furr, M; Saville, W J A; Williams, N M

2013-01-01

Recent work demonstrated the value of antigen-specific antibody indices (AI and C-value) to detect intrathecal antibody production against Sarcocystis neurona for antemortem diagnosis of equine protozoal myeloencephalitis (EPM). The study was conducted to assess whether the antigen-specific antibody indices can be reduced to a simple serum : cerebrospinal fluid (CSF) titer ratio to achieve accurate EPM diagnosis. Paired serum and CSF samples from 128 horses diagnosed by postmortem examination. The sample set included 44 EPM cases, 35 cervical-vertebral malformation (CVM) cases, 39 neurologic cases other than EPM or CVM, and 10 non-neurologic cases. Antibodies against S. neurona were measured in serum and CSF pairs using the SnSAG2 and SnSAG4/3 (SnSAG2, 4/3) ELISAs, and the ratio of each respective serum titer to CSF titer was determined. Likelihood ratios and diagnostic sensitivity and specificity were calculated based on serum titers, CSF titers, and serum : CSF titer ratios. Excellent diagnostic sensitivity and specificity was obtained from the SnSAG2, 4/3 serum : CSF titer ratio. Sensitivity and specificity of 93.2 and 81.1%, respectively, were achieved using a ratio cutoff of ≤100, whereas sensitivity and specificity were 86.4 and 95.9%, respectively, if a more rigorous cutoff of ≤50 was used. Antibody titers in CSF also provided good diagnostic accuracy. Serum antibody titers alone yielded much lower sensitivity and specificity. The study confirms the value of detecting intrathecal antibody production for antemortem diagnosis of EPM, and they further show that the antigen-specific antibody indices can be reduced in practice to a simple serum : CSF titer ratio. Copyright © 2013 by the American College of Veterinary Internal Medicine.

A simple, rapid, cost-effective and sensitive method for detection of Salmonella in environmental and pecan samples.

PubMed

Dobhal, S; Zhang, G; Rohla, C; Smith, M W; Ma, L M

2014-10-01

PCR is widely used in the routine detection of foodborne human pathogens; however, challenges remain in overcoming PCR inhibitors present in some sample matrices. The objective of this study was to develop a simple, sensitive, cost-effective and rapid method for processing large numbers of environmental and pecan samples for Salmonella detection. This study was also aimed at validation of a new protocol for the detection of Salmonella from in-shell pecans. Different DNA template preparation methods, including direct boiling, prespin, multiple washing and commercial DNA extraction kits, were evaluated with pure cultures of Salmonella Typhimurium and with enriched soil, cattle feces and in-shell pecan each spiked individually with Salmonella Typhimurium. PCR detection of Salmonella was conducted using invA and 16S rRNA gene (internal amplification control) specific primers. The effect of amplification facilitators, including bovine serum albumin (BSA), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and gelatin on PCR sensitivity, was also evaluated. Conducting a prespin of sample matrices in combination with the addition of 0·4% (w/v) BSA and 1% (w/v) PVP in PCR mix was the simplest, most rapid, cost-effective and sensitive method for PCR detection of Salmonella, with up to 40 CFU Salmonella per reaction detectable in the presence of over 10(9 ) CFU ml(-1) of background micro-organisms from enriched feces soil or pecan samples. The developed method is rapid, cost-effective and sensitive for detection of Salmonella from different matrices. This study provides a method with broad applicability for PCR detection of Salmonella in complex sample matrices. This method has a potential for its application in different research arenas and diagnostic laboratories. © 2014 The Society for Applied Microbiology.

A composite CdS thin film/TiO2 nanotube structure by ultrafast successive electrochemical deposition toward photovoltaic application

NASA Astrophysics Data System (ADS)

Fu, Han; Liu, Hong; Shen, Wenzhong

2014-11-01

Fabricating functional compounds on substrates with complicated morphology has been an important topic in material science and technology, which remains a challenging issue to simultaneously achieve a high growth rate for a complex nanostructure with simple controlling factors. Here, we present a novel simple and successive method based on chemical reactions in an open reaction system manipulated by an electric field. A uniform CdS/TiO2 composite tubular structure has been fabricated in highly ordered TiO2 nanotube arrays in a very short time period (~90 s) under room temperature (RT). The content of CdS in the resultant and its crystalline structure was tuned by the form and magnitude of external voltage. The as-formed structure has shown a quite broad and bulk-like light absorption spectrum with the absorption of photon energy even below that of the bulk CdS. The as-fabricated-sensitized solar cell based on this composite structure has achieved an efficiency of 1.43% without any chemical doping or co-sensitizing, 210% higher than quantum dot-sensitized solar cell (QDSSC) under a similar condition. Hopefully, this method can also easily grow nanostructures based on a wide range of compound materials for energy science and electronic technologies, especially for fast-deploying devices.

Nanoplasmonic biochips for rapid label-free detection of imidacloprid pesticides with a smartphone.

PubMed

Lee, Kuang-Li; You, Meng-Lin; Tsai, Chia-Hsin; Lin, En-Hung; Hsieh, Shu-Yi; Ho, Ming-Hsun; Hsu, Ju-Chun; Wei, Pei-Kuen

2016-01-15

The widespread and intensive use of neonicotinoid insecticides induces negative cascading effects on ecosystems. It is desirable to develop a portable sensitive sensing platform for on-site screening of high-risk pesticides. We combined an indirect competitive immunoassay, highly sensitive surface plasmon resonance (SPR) biochip and a simple portable imaging setup for label-free detection of imidacloprid pesticides. The SPR biochip consists of several capped nanoslit arrays with different periods which form a spectral image on the chip. The qualitative and semiquantitative analyses of pesticides can be directly observed from the spot shift on the chip. The precise semiquantitative analyses can be further completed by using image processing in a smartphone. We demonstrate simultaneous detection of four different concentrations of imidacloprid pesticides. The visual detection limit is about 1ppb, which is well below the maximum residue concentration permitted by law (20ppb). Compared to the one-step strip assay, the proposed chip is capable of performing semiquantitative analyses and multiple detection. Compared to the enzyme-linked immunosorbent assay, our method is label-free and requires simple washing steps and short reaction time. In addition, the label-free chip has a comparable sensitivity but wider working range than those labeling techniques. Copyright © 2015 Elsevier B.V. All rights reserved.

Measurement of the line-of-sight velocity of high-altitude barium clouds A technique

NASA Technical Reports Server (NTRS)

Mende, S. B.; Harris, S. E.

1982-01-01

It is demonstrated that for maximizing the scientific output of future ionospheric and magnetospheric ion cloud release experiments a new type of instrument is required which will measure the line-of-sight velocity of the ion cloud by the Doppler technique. A simple instrument was constructed using a 5-cm diam solid Fabry-Perot etalon coupled to a low-light-level integrating TV camera. It was demonstrated that the system has both the sensitivity and spectral resolution for detection of ion clouds and measurement of their line-of-sight Doppler velocity. The tests consisted of (1) a field experiment using a rocket barium cloud release to check sensitivity, and (2) laboratory experiments to show the spectral resolving capabilities of the system. The instrument was found to be operational if the source was brighter than approximately 1 kR, and it had a wavelength resolution much better than 0.2 A, which corresponds to approximately 12 km/sec or in the case of barium ion an acceleration potential of 100 V. The instrument is rugged and, therefore, simple to use in field experiments or on flight instruments. The sensitivity limit of the instrument can be increased by increasing the size of the etalon.

Gelatin-modified gold nanoparticles for direct detection of urinary total gelatinase activity: Diagnostic value in bladder cancer.

PubMed

Nossier, Ahmed I; Mohammed, Ola S; Fakhr El-Deen, Rasha R; Zaghloul, Ashraf S; Eissa, Sanaa

2016-12-01

Matrix metalloproteinases (MMPs), in particularly gelatinases (MMP-2 and MMP-9) were reported as urinary markers of bladder cancer. In this work, we developed a simple colorimetric gold nanoparticle (AuNP) assay for rapid and sensitive detection of urinary total gelatinase activity based on the surface plasmon resonance (SPR) property of AuNPs. Gelatin-modified AuNPs were stably suspended in solution even upon addition of an aggregation inducer as 6-mercaptohexan-1-ol (6-MCH). Gelatinases digest gelatin capping. Subsequently, addition of 6-MCH leads to AuNPs aggregation with red to blue color shift. In a pilot study, results of the developed AuNP assay were consistent with zymography for qualitative detection of urinary total gelatinase activity. The sensitivity and specificity of both assays were 80% and 90.9% respectively. The absorption ratios, A 625 /A 530 of the reacted AuNP solutions were used to quantify the total gelatinase concentration. The best cut off value was 0.01895ng/μg protein, at which the sensitivity was 87.5% and the specificity was 86.4%. The developed AuNP assay is simple, low-cost and can aid non-invasive diagnosis of bladder cancer. Copyright © 2016 Elsevier B.V. All rights reserved.

The effect of nanoparticle enhanced sizing on the structural health monitoring sensitivity and mechanical properties of carbon fiber composites

NASA Astrophysics Data System (ADS)

Bowland, Christopher C.; Nguyen, Ngoc A.; Naskar, Amit K.

2018-03-01

With current carbon composites being introduced into new commercial market sectors, there is an opportunity to develop multifunctional composites, which are poised to be the next generation of composites that will see future commercial applications. This multifunctional attribute can be achieved via integrated nanomaterials, which are currently under-utilized in real-world applications despite significant research efforts focused on their synthesis. This research utilizes a simple, scalable approach to integrate various nanomaterials into carbon fiber composites by embedding the nanomaterials in the epoxy fiber sizing. Illustrated in this work is the effect of silicon carbide nanoparticle concentrations and dimensions on the structural health monitoring sensitivity of unidirectional carbon fiber composites. Additionally, the nanoparticles contribute to the overall damping property of the composites thus enabling tunable damping through simple variations in nanoparticle concentration and size. Not only does this nanoparticle sizing offer enhanced sensitivity and tunable damping, but it also maintains the mechanical integrity and performance of the composites, which demonstrates a truly multifunctional composite. Therefore, this research establishes an efficient route for combining nanomaterials research with real-world multifunctional composite applications using a technique that is easily scalable to the commercial level and is compatible with a wide range of fibers and nanomaterials.

Comparative ecology of H2 cycling in sedimentary and phototrophic ecosystems

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.; Albert, Daniel B.; Alperin, Marc J.; Bebout, Brad M.; Martens, Christopher S.; Des Marais, David J.

2002-01-01

The simple biochemistry of H2 is critical to a large number of microbial processes, affecting the interaction of organisms with each other and with the environment. The sensitivity of each of these processes to H2 can be described collectively, through the quantitative language of thermodynamics. A necessary prerequisite is to understand the factors that, in turn, control H2 partial pressures. These factors are assessed for two distinctly different ecosystems. In anoxic sediments from Cape Lookout Bight (North Carolina, USA), H2 partial pressures are strictly maintained at low, steady-state levels by H2-consuming organisms, in a fashion that can be quantitatively predicted by simple thermodynamic calculations. In phototrophic microbial mats from Baja California (Mexico), H2 partial pressures are controlled by the activity of light-sensitive H2-producing organisms, and consequently fluctuate over orders of magnitude on a daily basis. The differences in H2 cycling can subsequently impact any of the H2-sensitive microbial processes in these systems. In one example, methanogenesis in Cape Lookout Bight sediments is completely suppressed through the efficient consumption of H2 by sulfate-reducing bacteria; in contrast, elevated levels of H2 prevail in the producer-controlled phototrophic system, and methanogenesis occurs readily in the presence of 40 mM sulfate.

Ultra-sensitive detection of kanamycin for food safety using a reduced graphene oxide-based fluorescent aptasensor

NASA Astrophysics Data System (ADS)

Ha, Na-Reum; Jung, In-Pil; La, Im-Joung; Jung, Ho-Sup; Yoon, Moon-Young

2017-01-01

Overuse of antibiotics has caused serious problems, such as appearance of super bacteria, whose accumulation in the human body through the food chain is a concern. Kanamycin is a common antibiotic used to treat diverse infections; however, residual kanamycin can cause many side effects in humans. Thus, development of an ultra-sensitive, precise, and simple detection system for residual kanamycin in food products is urgently needed for food safety. In this study, we identified kanamycin-binding aptamers via a new screening method, and truncated variants were analyzed for optimization of the minimal sequence required for target binding. We found various aptamers with high binding affinity from 34.7 to 669 nanomolar Kdapp values with good specificity against kanamycin. Furthermore, we developed a reduced graphene oxide (RGO)-based fluorescent aptasensor for kanamycin detection. In this system, kanamycin was detected at a concentration as low as 1 pM (582.6 fg/mL). In addition, this method could detect kanamycin accurately in kanamycin-spiked blood serum and milk samples. Consequently, this simple, rapid, and sensitive kanamycin detection system with newly structural and functional analysis aptamer exhibits outstanding detection compared to previous methods and provides a new possibility for point of care testing and food safety.

Improved Analytical Sensitivity of Lateral Flow Assay using Sponge for HBV Nucleic Acid Detection.

PubMed

Tang, Ruihua; Yang, Hui; Gong, Yan; Liu, Zhi; Li, XiuJun; Wen, Ting; Qu, ZhiGuo; Zhang, Sufeng; Mei, Qibing; Xu, Feng

2017-05-02

Hepatitis B virus (HBV) infection is a serious public health problem, which can be transmitted through various routes (e.g., blood donation) and cause hepatitis, liver cirrhosis and liver cancer. Hence, it is necessary to do diagnostic screening for high-risk HBV patients in these transmission routes. Nowadays, protein-based technologies have been used for HBV testing, which however involve the issues of large sample volume, antibody instability and poor specificity. Nucleic acid hybridization-based lateral flow assay (LFA) holds great potential to address these limitations due to its low-cost, rapid, and simple features, but the poor analytical sensitivity of LFA restricts its application. In this study, we developed a low-cost, simple and easy-to-use method to improve analytical sensitivity by integrating sponge shunt into LFA to decrease the fluid flow rate. The thickness, length and hydrophobicity of the sponge shunt were sequentially optimized, and achieved 10-fold signal enhancement in nucleic acid testing of HBV as compared to the unmodified LFA. The enhancement was further confirmed by using HBV clinical samples, where we achieved the detection limit of 10 3 copies/ml as compared to 10 4 copies/ml in unmodified LFA. The improved LFA holds great potential for diseases diagnostics, food safety control and environment monitoring at point-of-care.

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

PubMed

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

2014-03-17

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

Tracking of Indels by DEcomposition is a Simple and Effective Method to Assess Efficiency of Guide RNAs in Zebrafish.

PubMed

Etard, Christelle; Joshi, Swarnima; Stegmaier, Johannes; Mikut, Ralf; Strähle, Uwe

2017-12-01

A bottleneck in CRISPR/Cas9 genome editing is variable efficiencies of in silico-designed gRNAs. We evaluated the sensitivity of the TIDE method (Tracking of Indels by DEcomposition) introduced by Brinkman et al. in 2014 for assessing the cutting efficiencies of gRNAs in zebrafish. We show that this simple method, which involves bulk polymerase chain reaction amplification and Sanger sequencing, is highly effective in tracking well-performing gRNAs in pools of genomic DNA derived from injected embryos. The method is equally effective for tracing INDELs in heterozygotes.

Simple morphological control over functional diversity of SERS materials

NASA Astrophysics Data System (ADS)

Semenova, A. A.; Goodilin, E. A.

2018-03-01

Nowadays, surface-enhanced Raman spectroscopy (SERS) becomes a promising universal low-cost and real-time tool in biomedical applications, medical screening or forensic analysis allowing for detection of different molecules below nanomolar concentrations. Silver nanoparticles and nanostructures have proven to be a common choice for SERS measurements due to a tunable plasmon resonance, high stability and facile fabrication methods. However, a proper design of silver-based nanomaterials for highly sensitive SERS applications still remains a challenge. In this work, effective and simple preparation methods of various silver nanostructures are proposed and systematically developed using aqueous diamminesilver (I) hydroxide as a precursor.

A simple synthesis of N-perfluoroacylated and N-acylated glycals of neuraminic acid with a cyclic aminic substituent at the 4α position as possible inhibitors of sialidases.

PubMed

Rota, Paola; Allevi, Pietro; Agnolin, Irene S; Mattina, Roberto; Papini, Nadia; Anastasia, Mario

2012-04-14

A simple protocol for the synthesis of N-perfluoroacylated and N-acylated glycals of neuraminic acid, with a secondary cyclic amine (morpholine or piperidine) at the 4α position, has been set-up, starting from peracetylated N-acetylneuraminic acid methyl ester that undergoes, sequentially to its direct N-transacylation followed by a C-4 amination, a β-elimination, and a selective hydrolysis of the ester functions, without affecting the sensitive perfluorinated amide. This journal is © The Royal Society of Chemistry 2012

Etched optical fiber vibration sensor to monitor health condition of beam like structures

NASA Astrophysics Data System (ADS)

Putha, Kishore; Dantala, Dinakar; Kamineni, Srimannarayana; Pachava, Vengal Rao

2013-06-01

Using a center etched single mode optical fiber, a simple vibration senor is designed to monitor the vibrations of a simply supported beam. The sensor has high linear response to the axial displacement of about 0.8 mm with a sensitivity of 32 mV/10 μm strain. The sensor is tested for periodic and suddenly released forces, and the results are found to coincide with the theoretical values. This simple design, small in size and low cost sensor may find applications in industry and civil engineering to monitor the vibrations of the beam structures and bridges.

Predicting the risk of malignancy in adnexal masses based on the Simple Rules from the International Ovarian Tumor Analysis group.

PubMed

Timmerman, Dirk; Van Calster, Ben; Testa, Antonia; Savelli, Luca; Fischerova, Daniela; Froyman, Wouter; Wynants, Laure; Van Holsbeke, Caroline; Epstein, Elisabeth; Franchi, Dorella; Kaijser, Jeroen; Czekierdowski, Artur; Guerriero, Stefano; Fruscio, Robert; Leone, Francesco P G; Rossi, Alberto; Landolfo, Chiara; Vergote, Ignace; Bourne, Tom; Valentin, Lil

2016-04-01

Accurate methods to preoperatively characterize adnexal tumors are pivotal for optimal patient management. A recent metaanalysis concluded that the International Ovarian Tumor Analysis algorithms such as the Simple Rules are the best approaches to preoperatively classify adnexal masses as benign or malignant. We sought to develop and validate a model to predict the risk of malignancy in adnexal masses using the ultrasound features in the Simple Rules. This was an international cross-sectional cohort study involving 22 oncology centers, referral centers for ultrasonography, and general hospitals. We included consecutive patients with an adnexal tumor who underwent a standardized transvaginal ultrasound examination and were selected for surgery. Data on 5020 patients were recorded in 3 phases from 2002 through 2012. The 5 Simple Rules features indicative of a benign tumor (B-features) and the 5 features indicative of malignancy (M-features) are based on the presence of ascites, tumor morphology, and degree of vascularity at ultrasonography. Gold standard was the histopathologic diagnosis of the adnexal mass (pathologist blinded to ultrasound findings). Logistic regression analysis was used to estimate the risk of malignancy based on the 10 ultrasound features and type of center. The diagnostic performance was evaluated by area under the receiver operating characteristic curve, sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), positive predictive value (PPV), negative predictive value (NPV), and calibration curves. Data on 4848 patients were analyzed. The malignancy rate was 43% (1402/3263) in oncology centers and 17% (263/1585) in other centers. The area under the receiver operating characteristic curve on validation data was very similar in oncology centers (0.917; 95% confidence interval, 0.901-0.931) and other centers (0.916; 95% confidence interval, 0.873-0.945). Risk estimates showed good calibration. In all, 23% of patients in the validation data set had a very low estimated risk (<1%) and 48% had a high estimated risk (≥30%). For the 1% risk cutoff, sensitivity was 99.7%, specificity 33.7%, LR+ 1.5, LR- 0.010, PPV 44.8%, and NPV 98.9%. For the 30% risk cutoff, sensitivity was 89.0%, specificity 84.7%, LR+ 5.8, LR- 0.13, PPV 75.4%, and NPV 93.9%. Quantification of the risk of malignancy based on the Simple Rules has good diagnostic performance both in oncology centers and other centers. A simple classification based on these risk estimates may form the basis of a clinical management system. Patients with a high risk may benefit from surgery by a gynecological oncologist, while patients with a lower risk may be managed locally. Copyright © 2016 Elsevier Inc. All rights reserved.

DETECTION OF LOW DOSE RADIATION-AND CHEMICALLY-INDUCED DNA DAMAGE USING TEMPERATURE DIFFERENTIAL FLUORESCENCE ASSAYS

EPA Science Inventory

Rapid, sensitive and simple assays for radiation- and chemically-induced DNA damage can be of significant benefit to a number of fields including radiation biology, clinical research, and environmental monitoring. Although temperature-induced DNA strand separation has been use...

SCIENTIFIC AND TECHNOLOGICAL SUPPORT ON IN VITRO ASSAYS FOR THE AGENCY'S ENDOCRINE DISRUPTOR SCREENING PROGRAM

EPA Science Inventory

In response to the 1996 legislative mandate for an endocrine screening and testing program, we are helping develop, standardize and validate relatively sensitive, robust and relatively simple methods for in vitro screening of chemicals that affect estrogen, and androgen function ...

Compact integrated dc SQUID gradiometer

NASA Astrophysics Data System (ADS)

de Waal, V. J.; Klapwijk, T. M.

1982-10-01

An all-niobium integrated system of first-order gradiometer and dc suprconducting quantum interference device (SQUID) has been developed. It is relatively simple to fabricate, has an overall size of 17×12 mm and a sensitivity of 3.5×10-12 T m-1 Hz-1/2.

Sensitive Small Area Photometer

ERIC Educational Resources Information Center

Levenson, M. D.

1970-01-01

Describes a simple photometer capable of measuring small light intensities over small areas. The inexpensive, easy-to- construct instrument is intended for use in a student laboratory to measure the light intensities in a diffraction experiment from single or multiple slits. Typical experimental results are presented along with the theoretical…

A Simple, Inexpensive Method for the Measurement of in vivo Intestinal Activity.

ERIC Educational Resources Information Center

Sallee, V. L.; Gaugl, J. F.

1980-01-01

Describes a system that monitors intestinal motility in vivo which is very sensitive, minimally injurious to the tissue, and inexpensive. Used are two balloons, one of which is inserted into the intestinal lumen and the other suspended from a force transducer. (CS)

The sensitivity of Galvanic Skin Response for assessing mental workload in Indonesia.

PubMed

Widyanti, Ari; Muslim, Khoirul; Sutalaksana, Iftikar Zahedi

2017-01-01

Objective measures have been shown to be equally sensitive in different cultures. However, these measures need special devices that are relatively expensive and need expertise to analyze the result. In Indonesia, there is a need for a sensitive and affordable mental workload measure. To evaluate the sensitivity of Galvanic Skin Response (GSR) in assessing mental workload in Indonesia. A total of 72 Indonesian students with normal visual capability. Participants were asked to work on visual memory search task with a secondary task of counting with three different levels of difficulty. GSR, Heart Rate Variability (HRV), and the NASA-TLX were administered prior to, during, and after the tasks. GSR measure was compared to NASA-TLX and HRV measures. Like the HRV, GSR showed to be sensitive in distinguishing rest and task condition significantly but not sensitive in distinguishing different levels of mental workload. In contrast, both the NASA-TLX and performance measure were sensitive in differentiating different levels of mental workload. GSR has potential as a simple, cost-effective tool for measuring mental workload in Indonesia.

Effect of dye extracting solvents and sensitization time on photovoltaic performance of natural dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Hossain, Md. Khalid; Pervez, M. Firoz; Mia, M. N. H.; Mortuza, A. A.; Rahaman, M. S.; Karim, M. R.; Islam, Jahid M. M.; Ahmed, Farid; Khan, Mubarak A.

In this study, natural dye sensitizer based solar cells were successfully fabricated and photovoltaic performance was measured. Sensitizer (turmeric) sources, dye extraction process, and photoanode sensitization time of the fabricated cells were analyzed and optimized. Dry turmeric, verdant turmeric, and powder turmeric were used as dye sources. Five distinct types of solvents were used for extraction of natural dye from turmeric. Dyes were characterized by UV-Vis spectrophotometric analysis. The extracted turmeric dye was used as a sensitizer in the dye sensitized solar cell's (DSSC) photoanode assembly. Nano-crystalline TiO2 was used as a film coating semiconductor material of the photoanode. TiO2 films on ITO glass substrate were prepared by simple doctor blade technique. The influence of the different parameters VOC, JSC, power density, FF, and η% on the photovoltaic characteristics of DSSCs was analyzed. The best energy conversion performance was obtained for 2 h adsorption time of dye on TiO2 nano-porous surface with ethanol extracted dye from dry turmeric.

Adjoint sensitivity analysis of a tumor growth model and its application to spatiotemporal radiotherapy optimization.

PubMed

Fujarewicz, Krzysztof; Lakomiec, Krzysztof

2016-12-01

We investigate a spatial model of growth of a tumor and its sensitivity to radiotherapy. It is assumed that the radiation dose may vary in time and space, like in intensity modulated radiotherapy (IMRT). The change of the final state of the tumor depends on local differences in the radiation dose and varies with the time and the place of these local changes. This leads to the concept of a tumor's spatiotemporal sensitivity to radiation, which is a function of time and space. We show how adjoint sensitivity analysis may be applied to calculate the spatiotemporal sensitivity of the finite difference scheme resulting from the partial differential equation describing the tumor growth. We demonstrate results of this approach to the tumor proliferation, invasion and response to radiotherapy (PIRT) model and we compare the accuracy and the computational effort of the method to the simple forward finite difference sensitivity analysis. Furthermore, we use the spatiotemporal sensitivity during the gradient-based optimization of the spatiotemporal radiation protocol and present results for different parameters of the model.

Changes in Purkinje cell simple spike encoding of reach kinematics during adaption to a mechanical perturbation.

PubMed

Hewitt, Angela L; Popa, Laurentiu S; Ebner, Timothy J

2015-01-21

The cerebellum is essential in motor learning. At the cellular level, changes occur in both the simple spike and complex spike firing of Purkinje cells. Because simple spike discharge reflects the main output of the cerebellar cortex, changes in simple spike firing likely reflect the contribution of the cerebellum to the adapted behavior. Therefore, we investigated in Rhesus monkeys how the representation of arm kinematics in Purkinje cell simple spike discharge changed during adaptation to mechanical perturbations of reach movements. Monkeys rapidly adapted to a novel assistive or resistive perturbation along the direction of the reach. Adaptation consisted of matching the amplitude and timing of the perturbation to minimize its effect on the reach. In a majority of Purkinje cells, simple spike firing recorded before and during adaptation demonstrated significant changes in position, velocity, and acceleration sensitivity. The timing of the simple spike representations change within individual cells, including shifts in predictive versus feedback signals. At the population level, feedback-based encoding of position increases early in learning and velocity decreases. Both timing changes reverse later in learning. The complex spike discharge was only weakly modulated by the perturbations, demonstrating that the changes in simple spike firing can be independent of climbing fiber input. In summary, we observed extensive alterations in individual Purkinje cell encoding of reach kinematics, although the movements were nearly identical in the baseline and adapted states. Therefore, adaption to mechanical perturbation of a reaching movement is accompanied by widespread modifications in the simple spike encoding. Copyright © 2015 the authors 0270-6474/15/351106-19$15.00/0.

Changes in Purkinje Cell Simple Spike Encoding of Reach Kinematics during Adaption to a Mechanical Perturbation

PubMed Central

Hewitt, Angela L.; Popa, Laurentiu S.

2015-01-01

The cerebellum is essential in motor learning. At the cellular level, changes occur in both the simple spike and complex spike firing of Purkinje cells. Because simple spike discharge reflects the main output of the cerebellar cortex, changes in simple spike firing likely reflect the contribution of the cerebellum to the adapted behavior. Therefore, we investigated in Rhesus monkeys how the representation of arm kinematics in Purkinje cell simple spike discharge changed during adaptation to mechanical perturbations of reach movements. Monkeys rapidly adapted to a novel assistive or resistive perturbation along the direction of the reach. Adaptation consisted of matching the amplitude and timing of the perturbation to minimize its effect on the reach. In a majority of Purkinje cells, simple spike firing recorded before and during adaptation demonstrated significant changes in position, velocity, and acceleration sensitivity. The timing of the simple spike representations change within individual cells, including shifts in predictive versus feedback signals. At the population level, feedback-based encoding of position increases early in learning and velocity decreases. Both timing changes reverse later in learning. The complex spike discharge was only weakly modulated by the perturbations, demonstrating that the changes in simple spike firing can be independent of climbing fiber input. In summary, we observed extensive alterations in individual Purkinje cell encoding of reach kinematics, although the movements were nearly identical in the baseline and adapted states. Therefore, adaption to mechanical perturbation of a reaching movement is accompanied by widespread modifications in the simple spike encoding. PMID:25609626

The fabrication of nitrogen detector porous silicon nanostructures

NASA Astrophysics Data System (ADS)

Husairi, F. S.; Othman, N.; Eswar, K. A.; Guliling, Muliyadi; Khusaimi, Z.; Rusop, M.; Abdullah, S.

2018-05-01

In this study the porous silicon nanostructure used as a the nitrogen detector was fabricated by using anodization method because of simple and easy to handle. This method using 20 mA/ cm2 of current density and the etching time is from 10 - 40 minutes. The properties of the porous silicon nanostructure analyzed using I-V testing (electrical properties) and photoluminescence spectroscopy. From the I-V testing, sample PsiE40 where the sensitivity is 25.4% is a sensitivity of PSiE40 at 10 seconds exposure time.

Flip-Flop Recovery System for sounding rocket payloads

NASA Technical Reports Server (NTRS)

Flores, A., Jr.

1986-01-01

The design, development, and testing of the Flip-Flop Recovery System, which protects sensitive forward-mounted instruments from ground impact during sounding rocket payload recovery operations, are discussed. The system was originally developed to reduce the impact damage to the expensive gold-plated forward-mounted spectrometers in two existing Taurus-Orion rocket payloads. The concept of the recovery system is simple: the payload is flipped over end-for-end at a predetermined time just after parachute deployment, thus minimizing the risk of damage to the sensitive forward portion of the payload from ground impact.

Flow-injection system for automated dissolution testing of isoniazid tablets with chemiluminescence detection.

PubMed

Li, B; Zhang, Z; Liu, W

2001-05-30

A simple and sensitive flow-injection chemiluminescence (CL) system for automated dissolution testing is described and evaluated for monitoring of dissolution profiles of isoniazid tablets. The undissolved suspended particles in the dissolved solution were eliminated via on-line filter. The novel CL system of KIO(4)-isoniazid was also investigated. The sampling frequency of the system was 120 h(-1). The dissolution profiles of isoniazid fast-release tablets from three sources were determined, which demonstrates the stability, great sensitivity, large dynamic measuring range and robustness of the system.

The chemiluminescent response of human monocytes to red cells sensitized with monoclonal anti-Rh(D) antibodies.

PubMed

Hadley, A G; Kumpel, B M; Merry, A H

1988-01-01

Luminol-enhanced chemiluminescence (CL) was used to assess the metabolic response of human monocytes to red cells sensitized with known amounts of anti-Rh(D). Monoclonal antibodies were used to facilitate a comparison between the functional activities of IgG1 and IgG3 subclasses. The detection of CL provided a simple, rapid and semi-quantitative means of measuring monocyte response to sensitized red cells (IgG-RBC). Monocyte response to IgG3-RBC was quantitatively greater, more rapid and less susceptible to inhibition by fluid phase IgG than monocyte response to IgG1-RBC. The minimum levels of sensitization required to elicit CL from monocytes were approximately 2500 IgG3 molecules per red cell, or approximately 5000 IgG1 molecules per cell.

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

NASA Astrophysics Data System (ADS)

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

2013-05-01

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

The application of sensitizers from red frangipani flowers and star gooseberry leaves in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Almaz Dhafina, Wan; Salleh, Hasiah; Zalani Daud, Muhamad; Ali, Nora’aini

2018-05-01

Nowadays natural based dyes for dye-sensitized solar cells (DSSCs) have been in research field attention due to its advantages over other type of dyes such as low-cost, low-toxicity, completely biodegradable and abundance of resources. Natural dyes can be produced via the simple extraction method of pigments from plant parts such as flower, fruits, leaves, tuber etc. In this feature article, the natural dyes which composed of anthocyanin pigment from red frangipani flowers and chlorophyll from star gooseberry leaves were applied in zinc oxide, (ZnO) based-DSSC. The ZnO photoanode of the DSSCs sample were sensitized in each dye with different duration. It was observed that DSSCs which has chlorophyll pigment as dye had better performance with power conversion efficiency (PCE) of 0.007%.

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

PubMed

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

2017-06-12

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

Comparative study of dot enzyme immunoassay (Typhidot-M) and Widal test in the diagnosis of typhoid fever.

PubMed

Narayanappa, D; Sripathi, Rachana; Jagdishkumar, K; Rajani, H S

2010-04-01

We compared the sensitivity and specificity of Typhidot-M and Widal test with blood culture (gold standard) for diagnosing typhoid fever in 105 children aged 1-15 years admitted with clinical suspicion of typhoid fever. Of the 105 cases, blood culture was positive for S.typhi in 41 (39%) children, Widal test was positive in 48 (45.7%) and Typhidot-M was positive in 78 (74.3%) cases. Sensitivity and specificity of Typhidot-M was 92.6% and 37.5% while sensitivity and specificity of Widal test was 34.1% and 42.8%, respectively. In children with fever of less than 7 days duration, Typhidot-M was positive in 97%, compared to 24.2% by Widal test. Typhidot-M is a simple and sensitive test for early diagnosis of typhoid fever in children.

Temperature sensor based on an isopropanol-sealed photonic crystal fiber in-line interferometer with enhanced refractive index sensitivity.

PubMed

Qiu, Sun-jie; Chen, Ye; Xu, Fei; Lu, Yan-qing

2012-03-01

We fabricate a simple, compact, and stable temperature sensor based on a liquid-sealed photonic crystal fiber (PCF) in-line nonpolarimetric modal interferometer. Different from other reported PCF devices, it does not need expensive polarimetric devices, and the liquid is sealed in one fiber. The device consists of a stub of isopropanol-filled PCF spliced between standard single-mode fibers. The temperature sensitivity (-166 pm/°C) increases over an order of magnitude compared with those of the previous sensors based on air-sealed PCF interferometers built via fusion splicing with the same mechanism. In addition, the refractive index sensitivity also increases. Higher temperature sensitivity can be realized by infiltrating some liquid having a higher thermo-optic coefficient into the microholes of the PCF. © 2012 Optical Society of America

A Highly Sensitive Fiber Optic Sensor Based on Two-Core Fiber for Refractive Index Measurement

PubMed Central

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

2013-01-01

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

A Portable Smart-Phone Readout Device for the Detection of Mercury Contamination Based on an Aptamer-Assay Nanosensor.

PubMed

Xiao, Wei; Xiao, Meng; Fu, Qiangqiang; Yu, Shiting; Shen, Haicong; Bian, Hongfen; Tang, Yong

2016-11-08

The detection of environmental mercury (Hg) contamination requires complex and expensive instruments and professional technicians. We present a simple, sensitive, and portable Hg 2+ detection system based on a smartphone and colorimetric aptamer nanosensor. A smartphone equipped with a light meter app was used to detect, record, and process signals from a smartphone-based microwell reader (MR S-phone), which is composed of a simple light source and a miniaturized assay platform. The colorimetric readout of the aptamer nanosensor is based on a specific interaction between the selected aptamer and Hg 2+ , which leads to a color change in the reaction solution due to an aggregation of gold nanoparticles (AuNPs). The MR S-phone-based AuNPs-aptamer colorimetric sensor system could reliably detect Hg 2+ in both tap water and Pearl River water samples and produced a linear colorimetric readout of Hg 2+ concentration in the range of 1 ng/mL-32 ng/mL with a correlation of 0.991, and a limit of detection (LOD) of 0.28 ng/mL for Hg 2+ . The detection could be quickly completed in only 20 min. Our novel mercury detection assay is simple, rapid, and sensitive, and it provides new strategies for the on-site detection of mercury contamination in any environment.

A Portable Smart-Phone Readout Device for the Detection of Mercury Contamination Based on an Aptamer-Assay Nanosensor

PubMed Central

Xiao, Wei; Xiao, Meng; Fu, Qiangqiang; Yu, Shiting; Shen, Haicong; Bian, Hongfen; Tang, Yong

2016-01-01

The detection of environmental mercury (Hg) contamination requires complex and expensive instruments and professional technicians. We present a simple, sensitive, and portable Hg2+ detection system based on a smartphone and colorimetric aptamer nanosensor. A smartphone equipped with a light meter app was used to detect, record, and process signals from a smartphone-based microwell reader (MR S-phone), which is composed of a simple light source and a miniaturized assay platform. The colorimetric readout of the aptamer nanosensor is based on a specific interaction between the selected aptamer and Hg2+, which leads to a color change in the reaction solution due to an aggregation of gold nanoparticles (AuNPs). The MR S-phone-based AuNPs-aptamer colorimetric sensor system could reliably detect Hg2+ in both tap water and Pearl River water samples and produced a linear colorimetric readout of Hg2+ concentration in the range of 1 ng/mL–32 ng/mL with a correlation of 0.991, and a limit of detection (LOD) of 0.28 ng/mL for Hg2+. The detection could be quickly completed in only 20 min. Our novel mercury detection assay is simple, rapid, and sensitive, and it provides new strategies for the on-site detection of mercury contamination in any environment. PMID:27834794

A Simple Method Based on the Application of a CCD Camera as a Sensor to Detect Low Concentrations of Barium Sulfate in Suspension

PubMed Central

de Sena, Rodrigo Caciano; Soares, Matheus; Pereira, Maria Luiza Oliveira; da Silva, Rogério Cruz Domingues; do Rosário, Francisca Ferreira; da Silva, Joao Francisco Cajaiba

2011-01-01

The development of a simple, rapid and low cost method based on video image analysis and aimed at the detection of low concentrations of precipitated barium sulfate is described. The proposed system is basically composed of a webcam with a CCD sensor and a conventional dichroic lamp. For this purpose, software for processing and analyzing the digital images based on the RGB (Red, Green and Blue) color system was developed. The proposed method had shown very good repeatability and linearity and also presented higher sensitivity than the standard turbidimetric method. The developed method is presented as a simple alternative for future applications in the study of precipitations of inorganic salts and also for detecting the crystallization of organic compounds. PMID:22346607

Simple model to estimate the contribution of atmospheric CO2 to the Earth's greenhouse effect

NASA Astrophysics Data System (ADS)

Wilson, Derrek J.; Gea-Banacloche, Julio

2012-04-01

We show how the CO2 contribution to the Earth's greenhouse effect can be estimated from relatively simple physical considerations and readily available spectroscopic data. In particular, we present a calculation of the "climate sensitivity" (that is, the increase in temperature caused by a doubling of the concentration of CO2) in the absence of feedbacks. Our treatment highlights the important role played by the frequency dependence of the CO2 absorption spectrum. For pedagogical purposes, we provide two simple models to visualize different ways in which the atmosphere might return infrared radiation back to the Earth. The more physically realistic model, based on the Schwarzschild radiative transfer equations, uses as input an approximate form of the atmosphere's temperature profile, and thus includes implicitly the effect of heat transfer mechanisms other than radiation.

A simple method to extract DNA from hair shafts using enzymatic laundry powder.

PubMed

Guan, Zheng; Zhou, Yu; Liu, Jinchuan; Jiang, Xiaoling; Li, Sicong; Yang, Shuming; Chen, Ailiang

2013-01-01

A simple method to extract DNA from hair shafts was developed by using enzymatic laundry powder at the first step of the process. The whole extraction can be finished in less than 2 hours. The simple extraction reagent proposed here contains only two cheap components: ordinary enzymatic laundry powder and PCR buffer. After extraction, an ultra sensitive fluorescent nucleic acid stain, PicoGreen, was used for quantifying trace amount of double-stranded DNA in the solution extracted. For further validation of DNA extraction, four primers were employed to amplify DNA microsatellite loci. Both fluorescence spectroscopy and PCR results suggested that this method can extract DNA from hair shafts with good efficiency and repeatability. The study will greatly facilitate the use of hair shafts in future for DNA analyses on genome-wide scale.

Simple graphene chemiresistors as pH sensors: fabrication and characterization

NASA Astrophysics Data System (ADS)

Lei, Nan; Li, Pengfei; Xue, Wei; Xu, Jie

2011-10-01

We report the fabrication and characterization of a simple gate-free graphene device as a pH sensor. The graphene sheets are made by mechanical exfoliation. Platinum contact electrodes are fabricated with a mask-free process using a focused ion beam and then expanded by silver paint. Annealing is used to improve the electrical contact. The experiment on the fabricated graphene device shows that the resistance of the device decreases linearly with increasing pH values (in the range of 4-10) in the surrounding liquid environment. The resolution achieved in our experiments is approximately 0.3 pH in alkali environment. The sensitivity of the device is calculated as approximately 2 kΩ pH-1. The simple configuration, miniaturized size and integration ability make graphene-based sensors promising candidates for future micro/nano applications.

Improved Analysis of Earth System Models and Observations using Simple Climate Models

NASA Astrophysics Data System (ADS)

Nadiga, B. T.; Urban, N. M.

2016-12-01

Earth system models (ESM) are the most comprehensive tools we have to study climate change and develop climate projections. However, the computational infrastructure required and the cost incurred in running such ESMs precludes direct use of such models in conjunction with a wide variety of tools that can further our understanding of climate. Here we are referring to tools that range from dynamical systems tools that give insight into underlying flow structure and topology to tools that come from various applied mathematical and statistical techniques and are central to quantifying stability, sensitivity, uncertainty and predictability to machine learning tools that are now being rapidly developed or improved. Our approach to facilitate the use of such models is to analyze output of ESM experiments (cf. CMIP) using a range of simpler models that consider integral balances of important quantities such as mass and/or energy in a Bayesian framework.We highlight the use of this approach in the context of the uptake of heat by the world oceans in the ongoing global warming. Indeed, since in excess of 90% of the anomalous radiative forcing due greenhouse gas emissions is sequestered in the world oceans, the nature of ocean heat uptake crucially determines the surface warming that is realized (cf. climate sensitivity). Nevertheless, ESMs themselves are never run long enough to directly assess climate sensitivity. So, we consider a range of models based on integral balances--balances that have to be realized in all first-principles based models of the climate system including the most detailed state-of-the art climate simulations. The models range from simple models of energy balance to those that consider dynamically important ocean processes such as the conveyor-belt circulation (Meridional Overturning Circulation, MOC), North Atlantic Deep Water (NADW) formation, Antarctic Circumpolar Current (ACC) and eddy mixing. Results from Bayesian analysis of such models using both ESM experiments and actual observations are presented. One such result points to the importance of direct sequestration of heat below 700 m, a process that is not allowed for in the simple models that have been traditionally used to deduce climate sensitivity.

Forms of immunoreactive beta-endorphin in the intermediate pituitary of the holostean fish, Amia calva.

PubMed

Dores, R M; Sei, C A; Morrissey, M A; Crim, J W; Kawauchi, H

1988-01-01

Acid extracts of the intermediate pituitary of the holostean fish, Amia calva, were fractionated by gel filtration chromatography and analyzed with radioimmunoassays specific for N-acetylated beta-endorphin and C-terminally amidated alpha-MSH. In these extracts beta-endorphin-related immunoreactive material and alpha-MSH-related immunoreactive material were present in roughly equimolar amounts. The immunoreactive beta-endorphin-sized material was tested for opiate receptor binding activity using a beta-endorphin radioreceptor assay. The results of these studies were negative. The immunoreactive beta-endorphin-sized material was further analyzed by cation exchange chromatography at pH 2.5. Two major and three minor peaks of immunoreactive material were isolated. Peak 5 exhibited a net charge of +7 at pH 2.5 and represented 53% of the total immunoreactivity recovered. Peak 2 with a net charge of +3 at this pH represented 38% of the total immunoreactivity recovered. The minor forms, Peaks 1, 3 and 4, exhibited net charges of +2, +4 and +6, respectively. The apparent molecular weights of Peaks 2 and 5 were determined on a Sephadex G-50 column. Peak 2 had an apparent molecular weight of 2.7 Kd and Peak 5 had an apparent molecular weight of 3.5 Kd. Reverse phase HPLC analysis of Peak 5 indicates that this form of Amia beta-endorphin had chromatographic properties similar to salmon beta-endorphin II. These results would suggest that N-terminal acetylation and C-terminal proteolytic cleavage are important post-translational modifications of the forms of Amia beta-endorphin.

Modulation of central glucocorticoid receptors in short- and long-term experimental hyperthyroidism.

PubMed

Nikolopoulou, Elena; Mytilinaios, Dimitrios; Calogero, Aldo E; Kamilaris, Themis C; Troupis, Theodore; Chrousos, George P; Johnson, Elizabeth O

2015-08-01

Hyperthyroidism is associated with a significant increase in circulating glucocorticoid levels and hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. The aim of this study was to examine whether the HPA axis hyperactivity observed in hyperthyroidism may be explained by a disturbed feedback inhibition of endogenous glucocorticoids through two specific intracellular receptors in the brain: the high affinity mineralocorticoid receptor (MR) and the lower affinity glucocorticoid receptor (GR). Cytosolic receptor binding and gene expression was assessed in rats with short (7 days) and long standing (60 days) eu- and hyperthyroidism. Glucocorticoid receptor number and binding affinity (Kd) in the hippocampus were measured using [(3)H2]-dexamethasone radioreceptor assay. In situ hybridization was employed to examine the effects of hyperthyroidism on the GR and MR mRNA levels in the hippocampus and the pituitary. Both short- and long-term hyperthyroid rats showed pronounced reduction in the concentration of cytosolic GR in the hippocampus, without changes in binding affinity or changes in GR expression. In contrast, GR mRNA in the pituitary increased after 7 days and decreased after 60 days of thyroxin treatment. MR mRNA was moderately affected. Hyperthyroidism is associated with significant decreases in hippocampal GR levels supporting the hypothesis that hyperactivity of the HPA axis observed in experimentally induced hyperthyroidism may be attributed, at least in part, to decreased negative feedback at the level of the hippocampus. These findings further support the notion that a central locus is principally responsible for the hyperactivity of the HPA axis observed in hyperthyroidism.

The cognitive cost of anticholinergic burden: decreased response to cognitive training in schizophrenia.

PubMed

Vinogradov, Sophia; Fisher, Melissa; Warm, Heather; Holland, Christine; Kirshner, Margaret A; Pollock, Bruce G

2009-09-01

Schizophrenia is treated with medications that raise serum anticholinergic activity and are known to adversely affect cognition. The authors examined the relationship between serum anticholinergic activity and baseline cognitive performance and response to computerized cognitive training in outpatients with schizophrenia. Fifty-five patients were randomly assigned to either computerized cognitive training or a computer games control condition. A neurocognitive battery based on the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative was performed at baseline and after the intervention. Serum anticholinergic activity, measured at study entry by radioreceptor assay, was available for 49 patients. Serum anticholinergic activity showed a significant negative correlation with baseline performance in verbal working memory and verbal learning and memory, accounting for 7% of the variance in these measures, independent of age, IQ, or symptom severity. Patients in the cognitive training condition (N=25) showed a significant gain in global cognition compared to those in the control condition, but this improvement was negatively correlated with anticholinergic burden. Serum anticholinergic activity uniquely accounted for 20% of the variance in global cognition change, independent of age, IQ, or symptom severity. Serum anticholinergic activity in schizophrenia patients shows a significant association with impaired performance in MATRICS-based measures of verbal working memory and verbal learning and memory and is significantly associated with a lowered response to an intensive course of computerized cognitive training. These findings underscore the cognitive cost of medications that carry a high anticholinergic burden. The findings also have implications for the design and evaluation of cognitive treatments for schizophrenia.

Simple method to detect triacylglycerol biosynthesis in a yeast-based recombinant system

USDA-ARS?s Scientific Manuscript database

Standard methods to quantify the activity of triacylglycerol (TAG) synthesizing enzymes DGAT and PDAT (TAG-SE) require a sensitive but rather arduous laboratory assay based on radio-labeled substrates. Here we describe two straightforward methods to detect TAG production in baker’s yeast Saccharomyc...

Fast and Frugal Framing Effects?

ERIC Educational Resources Information Center

Mccloy, Rachel; Beaman, C. Philip; Frosch, Caren A.; Goddard, Kate

2010-01-01

Using 3 experiments, we examine whether simple pairwise comparison judgments, involving the "recognition heuristic" (Goldstein & Gigerenzer, 2002), are sensitive to implicit cues to the nature of the comparison required. In Experiments 1 and 2, we show that participants frequently choose the recognized option of a pair if asked to make "larger"…

Children Use Vowels to Help Them Spell Consonants

ERIC Educational Resources Information Center

Hayes, Heather; Treiman, Rebecca; Kessler, Brett

2006-01-01

English spelling is highly inconsistent in terms of simple sound-to-spelling correspondences but is more consistent when context is taken into account. For example, the choice between "ch" and "tch" is determined by the preceding vowel ("coach," "roach" vs. "catch," "hatch"). We investigated children's sensitivity to vowel context when spelling…

Intellectual Performance as a Function of Repression and Menstrual Cycle.

ERIC Educational Resources Information Center

Englander-Golden, Paula; And Others

Performance on complex (Space Relations and Verbal Reasoning) and simple (Digit Symbol) tests was investigated as a function of Byrne's Repression-Sensitization (RS) dimension, phase of menstrual cycle and premenstrual-menstrual (PM) symptomatology in a group of females not taking oral contraceptives. Two control groups, consisting of males and…

Prenatal Choline Availability Alters the Context Sensitivity of Pavlovian Conditioning in Adult Rats

ERIC Educational Resources Information Center

Lamoureux, Jeffrey A.; Meck, Warren H.; Williams, Christina L.

2008-01-01

The effects of prenatal choline availability on Pavlovian conditioning were assessed in adult male rats (3-4 mo). Neither supplementation nor deprivation of prenatal choline affected the acquisition and extinction of simple Pavlovian conditioned excitation, or the acquisition and retardation of conditioned inhibition. However, prenatal choline…

Improving College Instruction: A Strategy for Assisting Professors.

ERIC Educational Resources Information Center

Brightwell, D. Shelby

This paper proposes a strategy for analyzing and improving a college professor's approach to teaching. The strategy uses volunteer observers and a simple checklist, the Teacher Observation Checklist, of positive teaching behaviors drawn from the literature. Since college professors' sensitivity to examination and evaluation is high, this strategy…

Measurement of gaseous PAHs with an innovative passive sampler in community exposure studies

EPA Science Inventory

A sensitive, simple, and cost-effective passive sampling methodology was developed to quantify gaseous polycyclic aromatic hydrocarbons (PAHs) in personal, indoor and outdoor air. A Fan-Lioy passive PAH sampler (FL-PPS) is constructed from four 80 sections of 1 cm long SPB-5 GC c...

Detection of Convexity and Concavity in Context

ERIC Educational Resources Information Center

Bertamini, Marco

2008-01-01

Sensitivity to shape changes was measured, in particular detection of convexity and concavity changes. The available data are contradictory. The author used a change detection task and simple polygons to systematically manipulate convexity/concavity. Performance was high for detecting a change of sign (a new concave vertex along a convex contour…

Pyridoxylamine reactivity kinetics as an amine based nucleophile for screening electrophilic dermal sensitizers

PubMed Central

Chipinda, Itai; Mbiya, Wilbes; Adigun, Risikat Ajibola; Morakinyo, Moshood K.; Law, Brandon F.; Simoyi, Reuben H.; Siegel, Paul D.

2015-01-01

Chemical allergens bind directly, or after metabolic or abiotic activation, to endogenous proteins to become allergenic. Assessment of this initial binding has been suggested as a target for development of assays to screen chemicals for their allergenic potential. Recently we reported a nitrobenzenethiol (NBT) based method for screening thiol reactive skin sensitizers, however, amine selective sensitizers are not detected by this assay. In the present study we describe an amine (pyridoxylamine (PDA)) based kinetic assay to complement the NBT assay for identification of amine-selective and non-selective skin sensitizers. UV-Vis spectrophotometry and fluorescence were used to measure PDA reactivity for 57 chemicals including anhydrides, aldehydes, and quinones where reaction rates ranged from 116 to 6.2 × 10−6 M−1 s−1 for extreme to weak sensitizers, respectively. No reactivity towards PDA was observed with the thiol-selective sensitizers, non-sensitizers and prohaptens. The PDA rate constants correlated significantly with their respective murine local lymph node assay (LLNA) threshold EC3 values (R2 = 0.76). The use of PDA serves as a simple, inexpensive amine based method that shows promise as a preliminary screening tool for electrophilic, amine-selective skin sensitizers. PMID:24333919

Synthesis and Characterization of a New Co-Crystal Explosive with High Energy and Good Sensitivity

NASA Astrophysics Data System (ADS)

Gao, Han; Jiang, Wei; Liu, Jie; Hao, Gazi; Xiao, Lei; Ke, Xiang; Chen, Teng

2017-10-01

A new energetic co-crystal consisting of one of the most powerful explosive molecules 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and the military explosive cyclotrimethylenetrinitramine (RDX) was prepared with a simple solvent evaporation method. Scanning electron microscopy (SEM) revealed the morphology of the bar-shaped product, which differed greatly from the morphology of the individual components. Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction spectrum (XRD), and differential scanning calorimetry (DSC) proved the formation of the co-crystal at the molecular level. The result of mechanical sensitivity test indicated the sensitivity was effectively reduced compared to raw CL-20. Finally, a possible crystallization mechanism was discussed.

Temperature insensitive bending sensor based on in-line Mach-Zehnder interferometer

NASA Astrophysics Data System (ADS)

Chen, Xue; Yu, Yongqin; Xu, Xiaomei; Huang, Quandong; Ou, Zhilong; Wang, Jishun; Yan, Peiguang; Du, Chenlin

2014-09-01

A simple and compact fiber bending sensor based on the Mach-Zehnder interferometer was proposed. A photonic crystal fiber (PCF) with a length of 10 mm was spliced by collapsing air holes with two conventional single mode fibers to consist of an all fiber bending sensor. The sensitivity of 0.53 nm/m-1 was obtained at 1586 nm for the curvature range from 0 to 8.514 m-1. The temperature sensitivity was very low. The measurement error due to the temperature effect was about 8.68×10-3 m-1/°c, and the temperature effect in the curvature measurement could be ignored. This device can avoid the cross sensitivity of the temperature in the curvature measurement.

Demonstration of polarization-insensitive spatial light modulation using a single polarization-sensitive spatial light modulator

PubMed Central

Liu, Jun; Wang, Jian

2015-01-01

We present a simple configuration incorporating a single polarization-sensitive phase-only liquid crystal spatial light modulator (LC-SLM) to facilitate polarization-insensitive spatial light modulation. The polarization-insensitive configuration is formed by a polarization beam splitter (PBS), a polarization-sensitive phase-only LC-SLM, a half-wave plate (HWP), and a mirror in a loop structure. We experimentally demonstrate polarization-insensitive spatial light modulations for incident linearly polarized beams with different polarization states and polarization-multiplexed beams. Polarization-insensitive spatial light modulations generating orbital angular momentum (OAM) beams are demonstrated in the experiment. The designed polarization-insensitive configuration may find promising applications in spatial light modulations accommodating diverse incident polarizations. PMID:26146032

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

PubMed

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

1994-11-04

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

Capillary moving-boundary isotachophoresis with electrospray ionization mass-spectrometric detection and hydrogen ion used as essential terminator: Methodology for sensitive analysis of hydroxyderivatives of s-triazine herbicides in waters.

PubMed

Malá, Zdena; Gebauer, Petr

2017-10-06

Capillary isotachophoresis (ITP) is an electrophoretic technique offering high sensitivity due to permanent stacking of the migrating analytes. Its combination with electrospray-ionization mass-spectrometric (ESI-MS) detection is limited by the narrow spectrum of ESI-compatible components but can be compensated by experienced system architecture. This work describes a methodology for sensitive analysis of hydroxyderivatives of s-triazine herbicides, based on implementation of the concepts of moving-boundary isotachophoresis and of H + as essential terminating component into cationic ITP with ESI-MS detection. Theoretical description of such kind of system is given and equations for zone-related boundary mobilities are derived, resulting in a much more general definition of the effective mobility of the terminating H + zone than used so far. Explicit equations allowing direct calculation for selected simple systems are derived. The presented theory allows prediction of stacking properties of particular systems and easy selection of suitable electrolyte setups. A simple ESI-compatible system composed of acetic acid and ammonium with H + and ammonium as a mixed terminator was selected for the analysis of 2-hydroxyatrazine and 2-hydroxyterbutylazine, degradation products of s-triazine herbicides. The proposed method was tested with direct injection without any sample pretreatment and provided excellent linearity and high sensitivity with limits of detection below 100ng/L (0.5nM). Example analyses of unspiked and spiked drinking and river water are shown. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantum-Dot-Based Electrochemical Immunoassay for High-Throughput Screening of the Prostate-Specific Antigen

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

Wang, Jun; Liu, Guodong; Wu, Hong

2008-01-01

In this paper, we demonstrate an electrochemical high-throughput sensing platform for simple, sensitive detection of PSA based on QD labels. This sensing platform uses a microplate for immunoreactions and disposable screen-printed electrodes (SPE) for electrochemical stripping analysis of metal ions released from QD labels. With the 96-well microplate, capturing antibodies are conveniently immobilized to the well surface, and the process of immunoreaction is easily controlled. The formed sandwich complexes on the well surface are also easily isolated from reaction solutions. In particular, a microplate-based electrochemical assay can make it feasible to conduct a parallel analysis of several samples or multiplemore » protein markers. This assay offers a number of advantages including (1) simplicity, cost-effectiveness, (2) high sensitivity, (3) capability to sense multiple samples or targets in parallel, and (4) a potentially portable device with an SPE array implanted in the microplate. This PSA assay is sensitive because it uses two amplification processes: (1) QDs as a label for enhancing electrical signal since secondary antibodies are linked to QDs that contain a large number of metal atoms and (2) there is inherent signal amplification for electrochemical stripping analysis—preconcentration of metal ion onto the electrode surface for amplifying electrical signals. Therefore, the high sensitivity of this method, stemming from dual signal amplification via QD labels and pre-concentration, allows low concentration levels to be detected while using small sample volumes. Thus, this QD-based electrochemical detection approach offers a simple, rapid, cost-effective, and high throughput assay of PSA.« less

Flow cytometric chemosensitivity assay using JC‑1, a sensor of mitochondrial transmembrane potential, in acute leukemia.

PubMed

Yokosuka, Tomoko; Goto, Hiroaki; Fujii, Hisaki; Naruto, Takuya; Takeuchi, Masanobu; Tanoshima, Reo; Kato, Hiromi; Yanagimachi, Masakatsu; Kajiwara, Ryosuke; Yokota, Shumpei

2013-12-01

The purpose of the study is to establish a simple and relatively inexpensive flow cytometric chemosensitivity assay (FCCA) for leukemia to distinguish leukemic blasts from normal leukocytes in clinical samples. We first examined whether the FCCA with the mitochondrial membrane depolarization sensor, 5, 50, 6, 60-tetrachloro-1, 10, 3, 30 tetraethyl benzimidazolo carbocyanine iodide (JC-1), could detect drug-induced apoptosis as the conventional FCCA by annexin V/7-AAD detection did and whether it was applicable in the clinical samples. Second, we compared the results of the FCCA for prednisolone (PSL) with clinical PSL response in 18 acute lymphoblastic leukemia (ALL) patients to evaluate the reliability of the JC-1 FCCA. Finally, we performed the JC-1 FCCA for bortezomib (Bor) in 25 ALL or 11 acute myeloid leukemia (AML) samples as the example of the clinical application of the FCCA. In ALL cells, the results of the JC-1 FCCA for nine anticancer drugs were well correlated with those of the conventional FCCA using anti-annexin V antibody (P < 0.001). In the clinical samples from 18 children with ALL, the results of the JC-1 FCCA for PSL were significantly correlated with the clinical PSL response (P = 0.005). In ALL samples, the sensitivity for Bor was found to be significantly correlated with the sensitivity for PSL (P = 0.005). In AML samples, the Bor sensitivity was strongly correlated with the cytarabine sensitivity (P = 0.0003). This study showed the reliability of a relatively simple and the FCCA using JC-1, and the possibility for the further clinical application.

A novel approach to mask defect inspection

NASA Astrophysics Data System (ADS)

Sagiv, Amir; Shirman, Yuri; Mangan, Shmoolik

2008-10-01

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

Comparative Ecology of H2 Cycling in Organotrophic and Phototrophic Ecosystems

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.; Alperin, Marc J.; Albert, Daniel B.; Bebout, Brad M.; Martens, Christopher S.; DesMarais, David J.; DeVincenzi, Don (Technical Monitor)

2001-01-01

The simple biochemistry of H2 is critical to a large number of microbial processes, affecting the interaction of organisms with each other and with the environment. The sensitivity of these many processes to H2 can be described quantitatively, at a basic thermodynamic level. This shared dependence on H2 may provide a means for interpreting the ecology and system-level biogeochemistry of widely variant microbial ecosystems on a common (and quantitative) level. Understanding the factors that control H2 itself is a critical prerequisite. Here, we examine two ecosystems that vary widely with respect to H2 cycling. In anoxic, 'organotrophic' sediments from Cape Lookout Bight (North Carolina, USA), H2 partial pressures are strictly maintained at low, steady-state levels by H2-consuming organisms, in a fashion that can be quantitatively predicted by simple thermodynamic calculations. In phototrophic microbial mats from Baja, Mexico, H2 partial pressures are instead controlled by the activity of light-sensitive H2-producing organisms. In consequence, H2 partial pressures within the system fluctuate by orders of magnitude on hour-long time scales. The differences in H2 cycling subsequently impact H2-sensitive microbial processes, such as methanogenesis. For example, the presence of sulfate in the organotrophic system always yielded low levels of H2 that were inhibitory to methanogenesis; however, the elevated levels of H2 in the phototrophic system favored methane production at significant levels, even in the presence of high sulfate concentrations. The myriad of other H2-sensitive microbial processes are expected to exhibit similar behavior.

The Vermicelli Handling Test: A Simple Quantitative Measure of Dexterous Forepaw Function in Rats

PubMed Central

Allred, Rachel P.; Adkins, DeAnna L.; Woodlee, Martin T.; Husbands, Lincoln C.; Maldonado, Mónica A.; Kane, Jacqueline R.; Schallert, Timothy; Jones, Theresa A.

2008-01-01

Loss of function in the hands occurs with many brain disorders, but there are few measures of skillful forepaw use in rats available to model these impairments that are both sensitive and simple to administer. Whishaw and Coles (1996) previously described the dexterous manner in which rats manipulate food items with their paws, including thin pieces of pasta. We set out to develop a measure of this food handling behavior that would be quantitative, easy to administer, sensitive to the effects of damage to sensory and motor systems of the CNS and useful for identifying the side of lateralized impairments. When rats handle 7 cm lengths of vermicelli, they manipulate the pasta by repeatedly adjusting the forepaw hold on the pasta piece. As operationally defined, these adjustments can be easily identified and counted by an experimenter without specialized equipment. After unilateral sensorimotor cortex (SMC) lesions, transient middle cerebral artery occlusion (MCAO) and striatal dopamine depleting (6-hydroxydopamine, 6-OHDA) lesions in adult rats, there were enduring reductions in adjustments made with the contralateral forepaw. Additional pasta handling characteristics distinguished between the lesion types. MCAO and 6-OHDA lesions increased the frequency of several identified atypical handling patterns. Severe dopamine depletion increased eating time and adjustments made with the ipsilateral forepaw. However, contralateral forepaw adjustment number most sensitively detected enduring impairments across lesion types. Because of its ease of administration and sensitivity to lateralized impairments in skilled forepaw use, this measure may be useful in rat models of upper extremity impairment. PMID:18325597

DNA-stabilized silver nanoclusters and carbon nanoparticles oxide: A sensitive platform for label-free fluorescence turn-on detection of HIV-DNA sequences.

PubMed

Ye, Yu-Dan; Xia, Li; Xu, Dang-Dang; Xing, Xiao-Jing; Pang, Dai-Wen; Tang, Hong-Wu

2016-11-15

Based on the remarkable difference between the interactions of carbon nanoparticles (CNPs) oxide with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), and the fact that fluorescence of DNA-stabilized silver nanoclusters (AgNCs) can be quenched by CNPs oxide, DNA-functionalized AgNCs were applied as label-free fluorescence probes and a novel fluorescence resonance energy transfer (FRET) sensor was successfully constructed for the detection of human immunodeficiency virus (HIV) DNA sequences. CNPs oxide were prepared with the oxidation of candle soot, hence it is simple, time-saving and low-cost. The strategy of dual AgNCs probes was applied to improve the detection sensitivity by using dual- probe capturing the same target DNA in a sandwich mode and as the fluorescence donor, and using CNPs oxide as the acceptor. In the presence of target DNA, a dsDNA hybrid forms, leading to the desorption of the ssDNA-AgNCs probes from CNPs oxide, and the recovering of fluorescence of the AgNCs in a HIV-DNA concentration-dependent manner. The results show that HIV-DNA can be detected in the range of 1-50nM with a detection limit of 0.40nM in aqueous buffer. The method is simple, rapid and sensitive with no need of labeled fluorescent probes, and moreover, the design of fluorescent dual-probe makes full use of the excellent fluorescence property of AgNCs and further improves the detection sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

A portable smart-phone device for rapid and sensitive detection of E. coli O157:H7 in Yoghurt and Egg.

PubMed

Zeinhom, Mohamed Maarouf Ali; Wang, Yijia; Song, Yang; Zhu, Mei-Jun; Lin, Yuehe; Du, Dan

2018-01-15

The detection of E. coli O157:H7 in foods has held the attention of many researchers because of the seriousness attributed to this pathogen. In this study, we present a simple, sensitive, rapid and portable smartphone based fluorescence device for E. coli O157:H7 detection. This field-portable fluorescent imager on the smartphone involves a compact laser-diode-based photosource, a long-pass (LP) thin-film interference filter and a high-quality insert lenses. The design of the device provided a low noise to background imaging system. Based on a sandwich ELISA and the specific recognition of antibody to E. coli O157:H7, the sensitive detection of E. coli O157:H7 were realized both in standard samples and real matrix in yoghurt and egg on our device. The detection limit are 1 CFU/mL and 10 CFU/mL correspondingly. Recovery percentages of spiked yogurt and egg samples with 10 3 , 10 4 and 10 5 CFU/mL E. coli O157:H7 were 106.98, 96.52 and 102.65 (in yogurt) and 107.37, 105.64 and 93.84 (in egg) samples using our device, respectively. Most importantly, the entire process could be quickly completed within two hours. This smartphone based device provides a simple, rapid, sensitive detection platform for fluorescent imaging which applied in pathogen detection for food safety monitoring. Copyright © 2017 Elsevier B.V. All rights reserved.

pH-Assisted control over the binding and relocation of an acridine guest between a macrocyclic nanocarrier and natural DNA.

PubMed

Sayed, Mhejabeen; Pal, Haridas

2015-04-14

The differential binding affinity of the hydroxypropyl-β-cyclodextrin (HPβCD) macrocycle, a drug delivery vehicle, towards the protonated and deprotonated forms of the well-known DNA binder and model anticancer drug acridine has been exploited as a strategy for dye-drug transportation and pH-responsive delivery to a natural DNA target. From pH-sensitive changes in the ground state absorption and steady-state fluorescence characteristics of the studied acridine dye-HPβCD-DNA ternary system and strongly supported by fluorescence lifetime, fluorescence anisotropy, Job's plots, (1)H NMR and circular dichroism results, it is revealed that in a moderately alkaline solution (pH ∼ 8.5), the dye can be predominantly bound to the HPβCD macrocycle and when the pH is lowered to a moderately acidic region (pH ∼ 4), the dye efficiently detaches from the HPβCD cavity and almost exclusively binds to DNA. In the present study we are thus able to construct a pH-sensitive supramolecular assembly where pH acts as a simple stimulus for controlled uptake and targeted release of the dye-drug. As pH is an essential and sensitive factor in various biological processes, a simple yet reliable pH-sensitive model such as is demonstrated here can have promising applications in the host-assisted delivery of prodrug to the target sites, such as cancer or tumour microenvironments, with an enhanced stability, bioavailability and activity, and also in the design of new fluorescent probes, sensors and smart materials for applications in nano-science.

Electrochemical sensor for glutathione detection based on mercury ion triggered hybridization chain reaction signal amplification.

PubMed

Wang, Yonghong; Jiang, Lun; Leng, Qinggang; Wu, Yaohui; He, Xiaoxiao; Wang, Kemin

2016-03-15

In this work, we design a new simple and highly sensitive strategy for electrochemical detection of glutathione (GSH) via mercury ion (Hg(2+)) triggered hybridization chain reaction (HCR) signal amplification. It is observed that in the absence of GSH, a specific thymine-Hg(2+)-thymine (T-Hg(2+)-T) coordination can fold into hairpin structures. While in the presence of GSH, it thus can be chelated with Hg(2+), resulting in Hg(2+) released from the T-Hg(2+)-T hairpin complex which then forms into ssDNA structure to further hybridize with the surface-immobilized capture DNA probe on the gold electrode with a sticky tail left. The presence of two hairpin helper probes through HCR leads to the formation of extended dsDNA superstructure on the electrode surface, which therefore causes the intercalation of numerous electroactive species ([Ru(NH3)6](3+)) into the dsDNA grooves, followed by a significantly amplified signal output whose intensity is related to the concentration of the GSH. Taking advantage of merits of enzyme-free amplification power of the HCR, the inherent high sensitivity of the electrochemical technique, and label-free detection which utilizes an electroactive species as a signaling molecule that binds to the anionic phosphate backbone of DNA strands via electrostatic force, not only does the proposed strategy enable sensitive detection of GSH, but show high selectivity against other amino acid, making our method a simple and sensitive addition to the amplified GSH detection. Copyright © 2015 Elsevier B.V. All rights reserved.

Determining the best treatment for simple bone cyst: a decision analysis.

PubMed

Lee, Seung Yeol; Chung, Chin Youb; Lee, Kyoung Min; Sung, Ki Hyuk; Won, Sung Hun; Choi, In Ho; Cho, Tae-Joon; Yoo, Won Joon; Yeo, Ji Hyun; Park, Moon Seok

2014-03-01

The treatment of simple bone cysts (SBC) in children varies significantly among physicians. This study examined which procedure is better for the treatment of SBC, using a decision analysis based on current published evidence. A decision tree focused on five treatment modalities of SBC (observation, steroid injection, autologous bone marrow injection, decompression, and curettage with bone graft) were created. Each treatment modality was further branched, according to the presence and severity of complications. The probabilities of all cases were obtained by literature review. A roll back tool was utilized to determine the most preferred treatment modality. One-way sensitivity analysis was performed to determine the threshold value of the treatment modalities. Two-way sensitivity analysis was utilized to examine the joint impact of changes in probabilities of two parameters. The decision model favored autologous bone marrow injection. The expected value of autologous bone marrow injection was 0.9445, while those of observation, steroid injection, decompression, and curettage and bone graft were 0.9318, 0.9400, 0.9395, and 0.9342, respectively. One-way sensitivity analysis showed that autologous bone marrow injection was better than that of decompression for the expected value when the rate of pathologic fracture, or positive symptoms of SBC after autologous bone marrow injection, was lower than 20.4%. In our study, autologous bone marrow injection was found to be the best choice of treatment of SBC. However, the results were sensitive to the rate of pathologic fracture after treatment of SBC. Physicians should consider the possibility of pathologic fracture when they determine a treatment method for SBC.

Routine OGTT: a robust model including incretin effect for precise identification of insulin sensitivity and secretion in a single individual.

PubMed

De Gaetano, Andrea; Panunzi, Simona; Matone, Alice; Samson, Adeline; Vrbikova, Jana; Bendlova, Bela; Pacini, Giovanni

2013-01-01

In order to provide a method for precise identification of insulin sensitivity from clinical Oral Glucose Tolerance Test (OGTT) observations, a relatively simple mathematical model (Simple Interdependent glucose/insulin MOdel SIMO) for the OGTT, which coherently incorporates commonly accepted physiological assumptions (incretin effect and saturating glucose-driven insulin secretion) has been developed. OGTT data from 78 patients in five different glucose tolerance groups were analyzed: normal glucose tolerance (NGT), impaired glucose tolerance (IGT), impaired fasting glucose (IFG), IFG+IGT, and Type 2 Diabetes Mellitus (T2DM). A comparison with the 2011 Salinari (COntinuos GI tract MOdel, COMO) and the 2002 Dalla Man (Dalla Man MOdel, DMMO) models was made with particular attention to insulin sensitivity indices ISCOMO, ISDMMO and kxgi (the insulin sensitivity index for SIMO). ANOVA on kxgi values across groups resulted significant overall (P<0.001), and post-hoc comparisons highlighted the presence of three different groups: NGT (8.62×10(-5)±9.36×10(-5) min(-1)pM(-1)), IFG (5.30×10(-5)±5.18×10(-5)) and combined IGT, IFG+IGT and T2DM (2.09×10(-5)±1.95×10(-5), 2.38×10(-5)±2.28×10(-5) and 2.38×10(-5)±2.09×10(-5) respectively). No significance was obtained when comparing ISCOMO or ISDMMO across groups. Moreover, kxgi presented the lowest sample average coefficient of variation over the five groups (25.43%), with average CVs for ISCOMO and ISDMMO of 70.32% and 57.75% respectively; kxgi also presented the strongest correlations with all considered empirical measures of insulin sensitivity. While COMO and DMMO appear over-parameterized for fitting single-subject clinical OGTT data, SIMO provides a robust, precise, physiologically plausible estimate of insulin sensitivity, with which habitual empirical insulin sensitivity indices correlate well. The kxgi index, reflecting insulin secretion dependency on glycemia, also significantly differentiates clinically diverse subject groups. The SIMO model may therefore be of value for the quantification of glucose homeostasis from clinical OGTT data.

Statistical sensitivity analysis of a simple nuclear waste repository model

NASA Astrophysics Data System (ADS)

Ronen, Y.; Lucius, J. L.; Blow, E. M.

1980-06-01

A preliminary step in a comprehensive sensitivity analysis of the modeling of a nuclear waste repository. The purpose of the complete analysis is to determine which modeling parameters and physical data are most important in determining key design performance criteria and then to obtain the uncertainty in the design for safety considerations. The theory for a statistical screening design methodology is developed for later use in the overall program. The theory was applied to the test case of determining the relative importance of the sensitivity of near field temperature distribution in a single level salt repository to modeling parameters. The exact values of the sensitivities to these physical and modeling parameters were then obtained using direct methods of recalculation. The sensitivity coefficients found to be important for the sample problem were thermal loading, distance between the spent fuel canisters and their radius. Other important parameters were those related to salt properties at a point of interest in the repository.

Aging in Sensory and Motor Neurons Results in Learning Failure in Aplysia californica.

PubMed

Kempsell, Andrew T; Fieber, Lynne A

2015-01-01

The physiological and molecular mechanisms of age-related memory loss are complicated by the complexity of vertebrate nervous systems. This study takes advantage of a simple neural model to investigate nervous system aging, focusing on changes in learning and memory in the form of behavioral sensitization in vivo and synaptic facilitation in vitro. The effect of aging on the tail withdrawal reflex (TWR) was studied in Aplysia californica at maturity and late in the annual lifecycle. We found that short-term sensitization in TWR was absent in aged Aplysia. This implied that the neuronal machinery governing nonassociative learning was compromised during aging. Synaptic plasticity in the form of short-term facilitation between tail sensory and motor neurons decreased during aging whether the sensitizing stimulus was tail shock or the heterosynaptic modulator serotonin (5-HT). Together, these results suggest that the cellular mechanisms governing behavioral sensitization are compromised during aging, thereby nearly eliminating sensitization in aged Aplysia.

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

PubMed

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

2016-11-15

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

Organic photochemical storage of solar energy. Progress report, July 1, 1977--Feburary 28, 1978

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

Jones, G. II

1978-03-01

The prospects for driving endoergic reactions of simple, relatively abundant organic chemicals by photochemical means have been examined. Strategies for utilization of light of varying wavelength involve sensitization mechanisms which depend on the redox properties of energy storing substrates and photosensitizers. Of principal interest is valence isomerization which can be induced by electron donor-acceptor interaction between substrate and sensitizer in an excited complex or exciplex. Photophysical studies show that potentially isomerizable substrates efficiently intercept redox photosensitizers. The quenching of emission of electron acceptor sensitizers by non conjugated hydrocarbon dienes is indeed a function of the reduction potential of the acceptorsmore » (a series of aromatics with varying absorption characteristics) and the oxidation potentials of the substrates. Electron deficient dienes have been shown alternatively to be efficient quenchers of excited donor sensitizers. That exciplexes are formed between isomerizable substrates and donor or acceptor sensitizers has been confirmed by emission spectroscopy. The rearrangement of hexamethyldewarbenzene, a model exciplex isomerization has been examined in some detail.« less

Research on dual-parameter optical fiber sensor based on few-mode fiber with two down-tapers

NASA Astrophysics Data System (ADS)

Wang, Xue; Tong, Zhengrong; Zhang, Weihua; Xue, Lifang

2017-10-01

A dual-parameter optical fiber sensor, which is fabricated by sandwiching a segment of few-mode fiber (FMF) with two down-tapers between two segments of standard single-mode fibers (SMFs), is investigated theoretically and experimentally. The two down-tapers on the FMF can enhance the evanescent field, making the sensor more sensitive to changes in the external environment. The refractive index (RI) and temperature are measured simultaneously using the different sensitivities of the two dips in this experimental interference spectrum. The measured temperature sensitivities are 0.097 and 0.114 nm/°C, and the RI sensitivities are -97.43 and -108.07 nm/RIU, respectively. Meanwhile, the simple SMF-FMF-SMF structure is also measured. By comparing the experimental results of the two structures, the sensitivities of the proposed structure based on the dual-taper FMF are significantly improved. In addition, the sensor is easy to fabricate and cost effective.

Brain imaging of pain sensitization in patients with knee osteoarthritis.

PubMed

Pujol, Jesus; Martínez-Vilavella, Gerard; Llorente-Onaindia, Jone; Harrison, Ben J; López-Solà, Marina; López-Ruiz, Marina; Blanco-Hinojo, Laura; Benito, Pere; Deus, Joan; Monfort, Jordi

2017-09-01

A relevant aspect in osteoarthritic pain is neural sensitization. This phenomenon involves augmented responsiveness to painful stimulation and may entail a clinically worse prognosis. We used functional magnetic resonance imaging (fMRI) to study pain sensitization in patients with knee osteoarthritis. Sixty patients were recruited and pain sensitization was clinically defined on the basis of regional spreading of pain (spreading sensitization) and increased pain response to repeated stimulation (temporal summation). Functional magnetic resonance imaging testing involved assessing brain responses to both pressure and heat stimulation. Thirty-three patients (55%) showed regional pain spreading (simple sensitization) and 19 patients (32%) showed both regional spreading and temporal summation. Sensitized patients were more commonly women. Direct painful pressure stimulation of the joint (articular interline) robustly activated all of the neural elements typically involved in pain perception, but did not differentiate sensitized and nonsensitized patients. Painful pressure stimulation on the anterior tibial surface (sensitized site) evoked greater activation in sensitized patients in regions typically involved in pain and also beyond these regions, extending to the auditory, visual, and ventral sensorimotor cortices. Painful heat stimulation of the volar forearm did not discriminate the sensitization phenomenon. Results confirm the high prevalence of pain sensitization secondary to knee osteoarthritis. Relevantly, the sensitization phenomenon was associated with neural changes extending beyond strict pain-processing regions with enhancement of activity in general sensory, nonnociceptive brain areas. This effect is in contrast to the changes previously identified in primary pain sensitization in fibromyalgia patients presenting with a weakening of the general sensory integration.

Blurring the Inputs: A Natural Language Approach to Sensitivity Analysis

NASA Technical Reports Server (NTRS)

Kleb, William L.; Thompson, Richard A.; Johnston, Christopher O.

2007-01-01

To document model parameter uncertainties and to automate sensitivity analyses for numerical simulation codes, a natural-language-based method to specify tolerances has been developed. With this new method, uncertainties are expressed in a natural manner, i.e., as one would on an engineering drawing, namely, 5.25 +/- 0.01. This approach is robust and readily adapted to various application domains because it does not rely on parsing the particular structure of input file formats. Instead, tolerances of a standard format are added to existing fields within an input file. As a demonstration of the power of this simple, natural language approach, a Monte Carlo sensitivity analysis is performed for three disparate simulation codes: fluid dynamics (LAURA), radiation (HARA), and ablation (FIAT). Effort required to harness each code for sensitivity analysis was recorded to demonstrate the generality and flexibility of this new approach.

The unicellular fungal tool RhoTox for risk assessments in groundwater systems.

PubMed

Lategan, Maria Josie; Klare, William; Kidd, Sarah; Hose, Grant C; Nevalainen, Helena

2016-10-01

The recent inclusion of yeasts in environmental monitoring recognizes their ecological significance and sensitivity to toxicants. Here we present a robust and simple two-step toxicity assay and demonstrate the sensitivity of an ubiquitous groundwater yeast, Rhodotorula minuta, to a range of metals and metalloids. The test species was sensitive to copper with a 24h EC50 of 35µg Cu/L, followed in order of decreasing sensitivity by zinc, chromium (VI) and arsenic (EC50 4.40mg As (III)/L). The strain demonstrated an unexpected tolerance to chromium (VI), having an EC50 value (3.45mg Cr (VI)/L) similar to that of arsenic. The inclusion of a unicellular, microbial test-species into the suite of existing multicellular test species for toxicity evaluation is a key step towards strengthening the assessment of risk for groundwater ecosystems. Copyright © 2016 Elsevier Inc. All rights reserved.

Real-Time and In-Flow Sensing Using a High Sensitivity Porous Silicon Microcavity-Based Sensor.

PubMed

Caroselli, Raffaele; Martín Sánchez, David; Ponce Alcántara, Salvador; Prats Quilez, Francisco; Torrijos Morán, Luis; García-Rupérez, Jaime

2017-12-05

Porous silicon seems to be an appropriate material platform for the development of high-sensitivity and low-cost optical sensors, as their porous nature increases the interaction with the target substances, and their fabrication process is very simple and inexpensive. In this paper, we present the experimental development of a porous silicon microcavity sensor and its use for real-time in-flow sensing application. A high-sensitivity configuration was designed and then fabricated, by electrochemically etching a silicon wafer. Refractive index sensing experiments were realized by flowing several dilutions with decreasing refractive indices, and measuring the spectral shift in real-time. The porous silicon microcavity sensor showed a very linear response over a wide refractive index range, with a sensitivity around 1000 nm/refractive index unit (RIU), which allowed us to directly detect refractive index variations in the 10 -7 RIU range.

NEUROPSYCHOLOGICAL REMEDIATION OF HYPERACTIVE CHILDREN

PubMed Central

Agarwal, Neena; Rao, Shobini L.

1997-01-01

Hyperkinesis is associated with deficits of attention (poor allocation of attention resources, susceptibility to interference and perseveration); vigilance and perceptual sensitivity. Three boys aged 7-8 years with simple hyperkinesis were given cognitive tasks to improve the above functions in daily one hour sessions for a month. The children improved significantly in the above functions and behaviour. Three other children aged 5-8 years with simple hyperkinesis who were on medication improved only slightly in their behaviour during this period. Behavioural intervention and parental counselling were additional inputs to the children in both groups. Neuropsychological remediation combined with parental counselling and behavioural intervention shows promise in treating hyperactive children. PMID:21584098

A simple microfluidic Coriolis effect flowmeter for operation at high pressure and high temperature.

PubMed

Harrison, Christopher; Jundt, Jacques

2016-08-01

We describe a microfluidic Coriolis effect flowmeter that is simple to assemble, operates at elevated temperature and pressure, and can be operated with a lock-in amplifier. The sensor has a flow rate sensitivity greater than 2° of phase shift per 1 g/min of mass flow and is benchmarked with flow rates ranging from 0.05 to 2.0 g/min. The internal volume is 15 μl and uses off-the-shelf optical components to measure the tube motion. We demonstrate that fluid density can be calculated from the frequency of the resonating element with proper calibration.

Noninvasive control of dental calculus removal: qualification of two fluorescence methods

NASA Astrophysics Data System (ADS)

Gonchukov, S.; Sukhinina, A.; Bakhmutov, D.; Biryukova, T.

2013-02-01

The main condition of periodontitis prevention is the full calculus removal from the teeth surface. This procedure should be fulfilled without harming adjacent unaffected tooth tissues. Nevertheless the problem of sensitive and precise estimating of tooth-calculus interface exists and potential risk of hard tissue damage remains. In this work it was shown that fluorescence diagnostics during calculus removal can be successfully used for precise noninvasive detection of calculus-tooth interface. In so doing the simple implementation of this method free from the necessity of spectrometer using can be employed. Such a simple implementation of calculus detection set-up can be aggregated with the devices of calculus removing.

Simple and portable low frequency lock-in amplifier designed for photoacoustic measurements and its application to thermal effusivity determination in liquids

NASA Astrophysics Data System (ADS)

Ortega-Robles, Emmanuel; Cruz-Orea, Alfredo; Elías-Viñas, David

2018-03-01

The lock-in amplifier is a very useful instrument for observing very small signals under adverse signal-to-noise conditions. In this work, we describe a simple and portable lock-in amplifier designed to be used in photoacoustic measurements. The device was used to measure the thermal effusivity of eight different liquid samples (distilled water, glycerol, acetone, ethanol, 2-propanol, chloroform, hexane, and methanol), as well as the effusivity of acetone in aqueous solution at distinct concentrations, giving good results. The instrument has a bandwidth of 10 Hz-10 kHz and a sensitivity of 1 μV.

Robustifying blind image deblurring methods by simple filters

NASA Astrophysics Data System (ADS)

Liu, Yan; Zeng, Xiangrong; Huangpeng, Qizi; Fan, Jun; Zhou, Jinglun; Feng, Jing

2016-07-01

The state-of-the-art blind image deblurring (BID) methods are sensitive to noise, and most of them can deal with only small levels of Gaussian noise. In this paper, we use simple filters to present a robust BID framework which is able to robustify exiting BID methods to high-level Gaussian noise or/and Non-Gaussian noise. Experiments on images in presence of Gaussian noise, impulse noise (salt-and-pepper noise and random-valued noise) and mixed Gaussian-impulse noise, and a real-world blurry and noisy image show that the proposed method can faster estimate sharper kernels and better images, than that obtained by other methods.

Thermoelectric effects in graphene at high bias current and under microwave irradiation.

PubMed

Skoblin, Grigory; Sun, Jie; Yurgens, August

2017-11-14

We use a split top gate to induce doping of opposite signs in different parts of a graphene field-effect transistor, thereby effectively forming a graphene thermocouple. The thermocouple is sensitive to the electronic temperature in graphene, which can be several hundred kelvin higher than the ambient one at sufficiently high bias current. Combined with the high thermoelectric power of graphene, this allows for i) simple measurements of the electronic temperature and ii) building thermoelectric radiation detectors. A simple prototype graphene thermoelectric detector shows a temperature-independent optical responsivity of around 400 V/W at 94 GHz at temperatures of 4-50 K.

Sensory optimization by stochastic tuning.

PubMed

Jurica, Peter; Gepshtein, Sergei; Tyukin, Ivan; van Leeuwen, Cees

2013-10-01

Individually, visual neurons are each selective for several aspects of stimulation, such as stimulus location, frequency content, and speed. Collectively, the neurons implement the visual system's preferential sensitivity to some stimuli over others, manifested in behavioral sensitivity functions. We ask how the individual neurons are coordinated to optimize visual sensitivity. We model synaptic plasticity in a generic neural circuit and find that stochastic changes in strengths of synaptic connections entail fluctuations in parameters of neural receptive fields. The fluctuations correlate with uncertainty of sensory measurement in individual neurons: The higher the uncertainty the larger the amplitude of fluctuation. We show that this simple relationship is sufficient for the stochastic fluctuations to steer sensitivities of neurons toward a characteristic distribution, from which follows a sensitivity function observed in human psychophysics and which is predicted by a theory of optimal allocation of receptive fields. The optimal allocation arises in our simulations without supervision or feedback about system performance and independently of coupling between neurons, making the system highly adaptive and sensitive to prevailing stimulation. PsycINFO Database Record (c) 2013 APA, all rights reserved.

A high-sensitivity temperature sensor based on Sagnac interferometer employing photonic crystal fiber fully filled with ethanol

NASA Astrophysics Data System (ADS)

Shi, Min; Li, Shuguang; Chen, Hailiang

2018-06-01

A high-sensitivity temperature sensor based on photonic crystal fiber Sagnac interferometer is proposed and studied. All holes of the PCF are filled with ethanol with capillarity. The cladding air holes are uniform arrangements. The two air holes around the core are removed to form new core modes with high birefringence. The sensitivities of the temperature can be up to -8.7657 and 16.8142 nm/°C when temperature rises from 45 to 75 °C and the fiber length is 5.05 cm. And when temperature rises from 10 to 45 °C, the sensitivity can reach -7.848 and 16.655 nm/°C with fiber length 2.11 cm. The performance of the selective-filled and the fully-filled PCF with temperature from 45 to 75 °C and fiber length 5.05 cm are analyzed and compared. The fully filling can better achieve PCF's sensing performance. The simple structure and high sensitivities make the temperature sensor easy to achieve. The temperature sensor with high sensitivities and good linearity has great application value for environmental temperature detecting.

Simulation-based sensitivity analysis for non-ignorably missing data.

PubMed

Yin, Peng; Shi, Jian Q

2017-01-01

Sensitivity analysis is popular in dealing with missing data problems particularly for non-ignorable missingness, where full-likelihood method cannot be adopted. It analyses how sensitively the conclusions (output) may depend on assumptions or parameters (input) about missing data, i.e. missing data mechanism. We call models with the problem of uncertainty sensitivity models. To make conventional sensitivity analysis more useful in practice we need to define some simple and interpretable statistical quantities to assess the sensitivity models and make evidence based analysis. We propose a novel approach in this paper on attempting to investigate the possibility of each missing data mechanism model assumption, by comparing the simulated datasets from various MNAR models with the observed data non-parametrically, using the K-nearest-neighbour distances. Some asymptotic theory has also been provided. A key step of this method is to plug in a plausibility evaluation system towards each sensitivity parameter, to select plausible values and reject unlikely values, instead of considering all proposed values of sensitivity parameters as in the conventional sensitivity analysis method. The method is generic and has been applied successfully to several specific models in this paper including meta-analysis model with publication bias, analysis of incomplete longitudinal data and mean estimation with non-ignorable missing data.

Sonographic Diagnosis of Tubal Cancer with IOTA Simple Rules Plus Pattern Recognition

PubMed Central

Tongsong, Theera; Wanapirak, Chanane; Tantipalakorn, Charuwan; Tinnangwattana, Dangcheewan

2017-01-01

Objective: To evaluate diagnostic performance of IOTA simple rules plus pattern recognition in predicting tubal cancer. Methods: Secondary analysis was performed on prospective database of our IOTA project. The patients recruited in the project were those who were scheduled for pelvic surgery due to adnexal masses. The patients underwent ultrasound examinations within 24 hours before surgery. On ultrasound examination, the masses were evaluated using the well-established IOTA simple rules plus pattern recognition (sausage-shaped appearance, incomplete septum, visible ipsilateral ovaries) to predict tubal cancer. The gold standard diagnosis was based on histological findings or operative findings. Results: A total of 482 patients, including 15 cases of tubal cancer, were evaluated by ultrasound preoperatively. The IOTA simple rules plus pattern recognition gave a sensitivity of 86.7% (13 in 15) and specificity of 97.4%. Sausage-shaped appearance was identified in nearly all cases (14 in 15). Incomplete septa and normal ovaries could be identified in 33.3% and 40%, respectively. Conclusion: IOTA simple rules plus pattern recognition is relatively effective in predicting tubal cancer. Thus, we propose the simple scheme in diagnosis of tubal cancer as follows. First of all, the adnexal masses are evaluated with IOTA simple rules. If the B-rules could be applied, tubal cancer is reliably excluded. If the M-rules could be applied or the result is inconclusive, careful delineation of the mass with pattern recognition should be performed. PMID:29172273

Sonographic Diagnosis of Tubal Cancer with IOTA Simple Rules Plus Pattern Recognition

PubMed

Tongsong, Theera; Wanapirak, Chanane; Tantipalakorn, Charuwan; Tinnangwattana, Dangcheewan

2017-11-26

Objective: To evaluate diagnostic performance of IOTA simple rules plus pattern recognition in predicting tubal cancer. Methods: Secondary analysis was performed on prospective database of our IOTA project. The patients recruited in the project were those who were scheduled for pelvic surgery due to adnexal masses. The patients underwent ultrasound examinations within 24 hours before surgery. On ultrasound examination, the masses were evaluated using the well-established IOTA simple rules plus pattern recognition (sausage-shaped appearance, incomplete septum, visible ipsilateral ovaries) to predict tubal cancer. The gold standard diagnosis was based on histological findings or operative findings. Results: A total of 482 patients, including 15 cases of tubal cancer, were evaluated by ultrasound preoperatively. The IOTA simple rules plus pattern recognition gave a sensitivity of 86.7% (13 in 15) and specificity of 97.4%. Sausage-shaped appearance was identified in nearly all cases (14 in 15). Incomplete septa and normal ovaries could be identified in 33.3% and 40%, respectively. Conclusion: IOTA simple rules plus pattern recognition is relatively effective in predicting tubal cancer. Thus, we propose the simple scheme in diagnosis of tubal cancer as follows. First of all, the adnexal masses are evaluated with IOTA simple rules. If the B-rules could be applied, tubal cancer is reliably excluded. If the M-rules could be applied or the result is inconclusive, careful delineation of the mass with pattern recognition should be performed. Creative Commons Attribution License

Novel experimental design for high pressure-high temperature electrical resistance measurements in a "Paris-Edinburgh" large volume press.

PubMed

Matityahu, Shlomi; Emuna, Moran; Yahel, Eyal; Makov, Guy; Greenberg, Yaron

2015-04-01

We present a novel experimental design for high sensitivity measurements of the electrical resistance of samples at high pressures (0-6 GPa) and high temperatures (300-1000 K) in a "Paris-Edinburgh" type large volume press. Uniquely, the electrical measurements are carried out directly on a small sample, thus greatly increasing the sensitivity of the measurement. The sensitivity to even minor changes in electrical resistance can be used to clearly identify phase transitions in material samples. Electrical resistance measurements are relatively simple and rapid to execute and the efficacy of the present experimental design is demonstrated by measuring the electrical resistance of Pb, Sn, and Bi across a wide domain of temperature-pressure phase space and employing it to identify the loci of phase transitions. Based on these results, the phase diagrams of these elements are reconstructed to high accuracy and found to be in excellent agreement with previous studies. In particular, by mapping the locations of several well-studied reference points in the phase diagram of Sn and Bi, it is demonstrated that a standard calibration exists for the temperature and pressure, thus eliminating the need for direct or indirect temperature and pressure measurements. The present technique will allow simple and accurate mapping of phase diagrams under extreme conditions and may be of particular importance in advancing studies of liquid state anomalies.

Sensitivity and Bias in Decision-Making under Risk: Evaluating the Perception of Reward, Its Probability and Value

PubMed Central

Sharp, Madeleine E.; Viswanathan, Jayalakshmi; Lanyon, Linda J.; Barton, Jason J. S.

2012-01-01

Background There are few clinical tools that assess decision-making under risk. Tests that characterize sensitivity and bias in decisions between prospects varying in magnitude and probability of gain may provide insights in conditions with anomalous reward-related behaviour. Objective We designed a simple test of how subjects integrate information about the magnitude and the probability of reward, which can determine discriminative thresholds and choice bias in decisions under risk. Design/Methods Twenty subjects were required to choose between two explicitly described prospects, one with higher probability but lower magnitude of reward than the other, with the difference in expected value between the two prospects varying from 3 to 23%. Results Subjects showed a mean threshold sensitivity of 43% difference in expected value. Regarding choice bias, there was a ‘risk premium’ of 38%, indicating a tendency to choose higher probability over higher reward. An analysis using prospect theory showed that this risk premium is the predicted outcome of hypothesized non-linearities in the subjective perception of reward value and probability. Conclusions This simple test provides a robust measure of discriminative value thresholds and biases in decisions under risk. Prospect theory can also make predictions about decisions when subjective perception of reward or probability is anomalous, as may occur in populations with dopaminergic or striatal dysfunction, such as Parkinson's disease and schizophrenia. PMID:22493669

A composite CdS thin film/TiO2 nanotube structure by ultrafast successive electrochemical deposition toward photovoltaic application

PubMed Central

2014-01-01

Fabricating functional compounds on substrates with complicated morphology has been an important topic in material science and technology, which remains a challenging issue to simultaneously achieve a high growth rate for a complex nanostructure with simple controlling factors. Here, we present a novel simple and successive method based on chemical reactions in an open reaction system manipulated by an electric field. A uniform CdS/TiO2 composite tubular structure has been fabricated in highly ordered TiO2 nanotube arrays in a very short time period (~90 s) under room temperature (RT). The content of CdS in the resultant and its crystalline structure was tuned by the form and magnitude of external voltage. The as-formed structure has shown a quite broad and bulk-like light absorption spectrum with the absorption of photon energy even below that of the bulk CdS. The as-fabricated-sensitized solar cell based on this composite structure has achieved an efficiency of 1.43% without any chemical doping or co-sensitizing, 210% higher than quantum dot-sensitized solar cell (QDSSC) under a similar condition. Hopefully, this method can also easily grow nanostructures based on a wide range of compound materials for energy science and electronic technologies, especially for fast-deploying devices. PMID:25520588

How to interpret methylation sensitive amplified polymorphism (MSAP) profiles?

PubMed

Fulneček, Jaroslav; Kovařík, Aleš

2014-01-06

DNA methylation plays a key role in development, contributes to genome stability, and may also respond to external factors supporting adaptation and evolution. To connect different types of stimuli with particular biological processes, identifying genome regions with altered 5-methylcytosine distribution at a genome-wide scale is important. Many researchers are using the simple, reliable, and relatively inexpensive Methylation Sensitive Amplified Polymorphism (MSAP) method that is particularly useful in studies of epigenetic variation. However, electrophoretic patterns produced by the method are rather difficult to interpret, particularly when MspI and HpaII isoschizomers are used because these enzymes are methylation-sensitive, and any C within the CCGG recognition motif can be methylated in plant DNA. Here, we evaluate MSAP patterns with respect to current knowledge of the enzyme activities and the level and distribution of 5-methylcytosine in plant and vertebrate genomes. We discuss potential caveats related to complex MSAP patterns and provide clues regarding how to interpret them. We further show that addition of combined HpaII + MspI digestion would assist in the interpretation of the most controversial MSAP pattern represented by the signal in the HpaII but not in the MspI profile. We recommend modification of the MSAP protocol that definitely discerns between putative hemimethylated mCCGG and internal CmCGG sites. We believe that our view and the simple improvement will assist in correct MSAP data interpretation.

Sensitivity and bias in decision-making under risk: evaluating the perception of reward, its probability and value.

PubMed

Sharp, Madeleine E; Viswanathan, Jayalakshmi; Lanyon, Linda J; Barton, Jason J S

2012-01-01

There are few clinical tools that assess decision-making under risk. Tests that characterize sensitivity and bias in decisions between prospects varying in magnitude and probability of gain may provide insights in conditions with anomalous reward-related behaviour. We designed a simple test of how subjects integrate information about the magnitude and the probability of reward, which can determine discriminative thresholds and choice bias in decisions under risk. Twenty subjects were required to choose between two explicitly described prospects, one with higher probability but lower magnitude of reward than the other, with the difference in expected value between the two prospects varying from 3 to 23%. Subjects showed a mean threshold sensitivity of 43% difference in expected value. Regarding choice bias, there was a 'risk premium' of 38%, indicating a tendency to choose higher probability over higher reward. An analysis using prospect theory showed that this risk premium is the predicted outcome of hypothesized non-linearities in the subjective perception of reward value and probability. This simple test provides a robust measure of discriminative value thresholds and biases in decisions under risk. Prospect theory can also make predictions about decisions when subjective perception of reward or probability is anomalous, as may occur in populations with dopaminergic or striatal dysfunction, such as Parkinson's disease and schizophrenia.

Quantitative detection of bovine and porcine gelatin difference using surface plasmon resonance based biosensor

NASA Astrophysics Data System (ADS)

Wardani, Devy P.; Arifin, Muhammad; Suharyadi, Edi; Abraha, Kamsul

2015-05-01

Gelatin is a biopolymer derived from collagen that is widely used in food and pharmaceutical products. Due to some religion restrictions and health issues regarding the gelatin consumption which is extracted from certain species, it is necessary to establish a robust, reliable, sensitive and simple quantitative method to detect gelatin from different parent collagen species. To the best of our knowledge, there has not been a gelatin differentiation method based on optical sensor that could detect gelatin from different species quantitatively. Surface plasmon resonance (SPR) based biosensor is known to be a sensitive, simple and label free optical method for detecting biomaterials that is able to do quantitative detection. Therefore, we have utilized SPR-based biosensor to detect the differentiation between bovine and porcine gelatin in various concentration, from 0% to 10% (w/w). Here, we report the ability of SPR-based biosensor to detect difference between both gelatins, its sensitivity toward the gelatin concentration change, its reliability and limit of detection (LOD) and limit of quantification (LOQ) of the sensor. The sensor's LOD and LOQ towards bovine gelatin concentration are 0.38% and 1.26% (w/w), while towards porcine gelatin concentration are 0.66% and 2.20% (w/w), respectively. The results show that SPR-based biosensor is a promising tool for detecting gelatin from different raw materials quantitatively.

Gold nanoparticles based colorimetric nanodiagnostics for cancer and infectious diseases

NASA Astrophysics Data System (ADS)

Valentini, Paola; Persano, Stefano; Cecere, Paola; Sabella, Stefania; Pompa, Pier Paolo

2014-03-01

Traditional in vitro diagnostics requires specialized laboratories and costly instrumentation, both for the amplification of nucleic acid targets (usually achieved by PCR) and for the assay readout, often based on fluorescence. We are developing hybrid nanomaterials-based sensors for the rapid and low-cost diagnosis of various disease biomarkers, for applications in portable platforms for diagnostics at the point-of-care. To this aim, we exploited the size and distancedependent optical properties of gold nanoparticles (AuNPs) to achieve colorimetric detection. Moreover, in order to avoid the complexity of thermal cycles associated to traditional PCR, the design of our systems includes signal amplification schemes, achieved by the use of enzymes (nucleases, helicase) or DNAzymes. Focused on instrument-free and sensitive detection, we carefully combined the intrinsic sensitivity by multivalency of functionalized AuNPs with isothermal and non-stringent enzyme-aided reaction conditions, controlled AuNPs aggregates, universal reporters and magnetic microparticles, the latter used both as a substrate and as a means for the colorimetric detection. We obtained simple and robust assays for the sensitive (pM range or better) naked-eye detection of cancer or infectious diseases (HPV, HCV) biomarkers, requiring no instrumentation except for a simple heating plate. Finally, we are also developing non-medical applications of these bio-nanosensors, such as in the development of on-field rapid tests for the detection of pollutants and other food and water contaminants.

Turbidimeter Design and Analysis: A Review on Optical Fiber Sensors for the Measurement of Water Turbidity

PubMed Central

Omar, Ahmad Fairuz Bin; MatJafri, Mohd Zubir Bin

2009-01-01

Turbidimeters operate based on the optical phenomena that occur when incident light through water body is scattered by the existence of foreign particles which are suspended within it. This review paper elaborates on the standards and factors that may influence the measurement of turbidity. The discussion also focuses on the optical fiber sensor technologies that have been applied within the lab and field environment and have been implemented in the measurement of water turbidity and concentration of particles. This paper also discusses and compares results from three different turbidimeter designs that use various optical components. Mohd Zubir and Bashah and Daraigan have introduced a design which has simple configurations. Omar and MatJafri, on the other hand, have established a new turbidimeter design that makes use of optical fiber cable as the light transferring medium. The application of fiber optic cable to the turbidimeter will present a flexible measurement technique, allowing measurements to be made online. Scattered light measurement through optical fiber cable requires a highly sensitive detector to interpret the scattered light signal. This has made the optical fiber system have higher sensitivity in measuring turbidity compared to the other two simple turbidimeters presented in this paper. Fiber optic sensors provide the potential for increased sensitivity over large concentration ranges. However, many challenges must be examined to develop sensors that can collect reliable turbidity measurements in situ. PMID:22408507

Direct detection of hyaluronidase in urine using cationic gold nanoparticles: a potential diagnostic test for bladder cancer.

PubMed

Nossier, Ahmed Ibrahim; Eissa, Sanaa; Ismail, Manal Fouad; Hamdy, Mohamed Ahmed; Azzazy, Hassan Mohamed El-Said

2014-04-15

Hyaluronidase (HAase) was reported as a urinary marker of bladder cancer. In this study, a simple colorimetric gold nanoparticle (AuNP) assay was developed for rapid and sensitive detection of urinary HAase activity. Charge interaction between polyanionic hyaluronic acid (HA) and cationic AuNPs stabilized with cetyl trimethyl ammonium bromide (CTAB) led to formation of gold aggregates and a red to blue color shift. HAase digests HA into small fragments preventing the aggregation of cationic AuNPs. The nonspecific aggregation of AuNPs in urine samples was overcome by pre-treatment of samples with the polycationic chitosan that was able to agglomerate all negatively charged interfering moieties before performing the assay. The developed AuNP assay was compared with zymography for qualitative detection of urinary HAase activity in 40 bladder carcinoma patients, 11 benign bladder lesions patients and 15 normal individuals, the assay sensitivity was 82.5% vs. 65% for zymography, while the specificity for both assays was 96.1%. The absorption ratio, A530/A620 of the reacted AuNP solution was used to quantify the HAase activity. The best cut off value was 93.5 μU/ng protein, at which the sensitivity was 90% and the specificity was 80.8%.The developed colorimetric AuNP HAase assay is simple, inexpensive, and can aid noninvasive diagnosis of bladder cancer. © 2013 Elsevier B.V. All rights reserved.

Dark plasmonic mode based perfect absorption and refractive index sensing.

PubMed

Yang, W H; Zhang, C; Sun, S; Jing, J; Song, Q; Xiao, S

2017-07-06

Dark plasmonic resonances in metallic nanostructures are essential for many potential applications such as refractive index sensing, single molecule detection, nanolasers etc. However, it is difficult to excite the dark modes in optical experiments and thus the practical applications are severely limited. Herein, we demonstrate a simple method to experimentally excite the quadrupolar and higher-order plasmonic modes with normal incident light. By directionally depositing silver films onto the sidewalls of metal-covered one-dimensional grating, we have experimentally observed a series of asymmetrical resonances at the plasmonic ranges of silver gratings. Interestingly, both of the reflection and transmission coefficients of high-order plasmonic modes are reduced to around zero, demonstrating the perfect absorption very well. The corresponding numerical simulations show that these resonances are the well-known dark modes. Different from the conventional dark modes in plasmonic dimers, here the dark modes are the electric oscillations (as standing waves) within the silver sidewalls that are excited by charge accumulation via the bright plasmonic resonance of the top silver strips. In addition to the simple realization of perfect absorption, the dark modes are found to be quite sensitive to the environmental changes. The experimentally measured reflective index sensitivity is around 458 nm per RIU (refractive index unit), which is much higher than the sensitivity of the metal-covered grating without silver sidewalls. This research shall pave new routes to practical applications of dark surface plasmons.

An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

PubMed

Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Schelter, Eric J

2015-07-06

Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three η(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-earth metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Simple Method to Measure Nematodes' Propulsive Thrust and the Nematode Ratchet.

NASA Astrophysics Data System (ADS)

Bau, Haim; Yuan, Jinzhou; Raizen, David

2015-11-01

Since the propulsive thrust of micro organisms provides a more sensitive indicator of the animal's health and response to drugs than motility, a simple, high throughput, direct measurement of the thrust is desired. Taking advantage of the nematode C. elegans being heavier than water, we devised a simple method to determine the propulsive thrust of the animals by monitoring their velocity when swimming along an inclined plane. We find that the swimming velocity is a linear function of the sin of the inclination angle. This method allows us to determine, among other things, the animas' propulsive thrust as a function of genotype, drugs, and age. Furthermore, taking advantage of the animals' inability to swim over a stiff incline, we constructed a sawteeth ratchet-like track that restricts the animals to swim in a predetermined direction. This research was supported, in part, by NIH NIA Grant 5R03AG042690-02.

Simple colorimetric detection of doxycycline and oxytetracycline using unmodified gold nanoparticles

NASA Astrophysics Data System (ADS)

Li, Jie; Fan, Shumin; Li, Zhigang; Xie, Yuanzhe; Wang, Rui; Ge, Baoyu; Wu, Jing; Wang, Ruiyong

2014-08-01

The interaction between tetracycline antibiotics and gold nanoparticles was studied. With citrate-coated gold nanoparticles as colorimetric probe, a simple and rapid detection method for doxycycline and oxytetracycline has been developed. This method relies on the distance-dependent optical properties of gold nanoparticles. In weakly acidic buffer medium, doxycycline and oxytetracycline could rapidly induce the aggregation of gold nanoparticles, resulting in red-to-blue (or purple) colour change. The experimental parameters were optimized with regard to pH, the concentration of the gold nanoparticles and the reaction time. Under optimal experimental conditions, the linear range of the colorimetric sensor for doxycycline/oxytetracycline was 0.06-0.66 and 0.59-8.85 μg mL-1, respectively. The corresponding limit of detection for doxycycline and oxytetracycline was 0.0086 and 0.0838 μg mL-1, respectively. This assay was sensitive, selective, simple and readily used to detect tetracycline antibiotics in food products.

Evidence integration in model-based tree search

PubMed Central

Solway, Alec; Botvinick, Matthew M.

2015-01-01

Research on the dynamics of reward-based, goal-directed decision making has largely focused on simple choice, where participants decide among a set of unitary, mutually exclusive options. Recent work suggests that the deliberation process underlying simple choice can be understood in terms of evidence integration: Noisy evidence in favor of each option accrues over time, until the evidence in favor of one option is significantly greater than the rest. However, real-life decisions often involve not one, but several steps of action, requiring a consideration of cumulative rewards and a sensitivity to recursive decision structure. We present results from two experiments that leveraged techniques previously applied to simple choice to shed light on the deliberation process underlying multistep choice. We interpret the results from these experiments in terms of a new computational model, which extends the evidence accumulation perspective to multiple steps of action. PMID:26324932

Piezoresistive Sensor with High Elasticity Based on 3D Hybrid Network of Sponge@CNTs@Ag NPs.

PubMed

Zhang, Hui; Liu, Nishuang; Shi, Yuling; Liu, Weijie; Yue, Yang; Wang, Siliang; Ma, Yanan; Wen, Li; Li, Luying; Long, Fei; Zou, Zhengguang; Gao, Yihua

2016-08-31

Pressure sensors with high elasticity are in great demand for the realization of intelligent sensing, but there is a need to develope a simple, inexpensive, and scalable method for the manufacture of the sensors. Here, we reported an efficient, simple, facile, and repeatable "dipping and coating" process to manufacture a piezoresistive sensor with high elasticity, based on homogeneous 3D hybrid network of carbon nanotubes@silver nanoparticles (CNTs@Ag NPs) anchored on a skeleton sponge. Highly elastic, sensitive, and wearable sensors are obtained using the porous structure of sponge and the synergy effect of CNTs/Ag NPs. Our sensor was also tested for over 2000 compression-release cycles, exhibiting excellent elasticity and cycling stability. Sensors with high performance and a simple fabrication process are promising devices for commercial production in various electronic devices, for example, sport performance monitoring and man-machine interfaces.

A simple heterogeneous one-step assay for screening estrogenic compounds.

PubMed

Huovinen, Tuomas; Rytkönen, Kalle; Lamminmäki, Urpo; Pellinen, Teijo

2013-01-01

Estrogen receptor (ER) modulators are a serious health issue but estrogenic compounds, especially antagonists of ER function, are widely screened for in search of novel therapeutics against hormonal diseases such as the breast cancer. Here we report a novel and a simple bioassay for estrogenic and anti-estrogenic compounds based on ligand-dependent recruitment of ER co-activator steroid receptor co-activator 1 (SRC-1) to purified Renilla luciferase-tagged ERα. In this assay, in vivo-biotinylated (E. coli) SRC-1, purified Renilla luciferase-ERα, and the analyte sample are mixed and incubated for 2 h in a streptavidin-coated microtiter wells, and after one washing step, luminescence is measured with a simple instrument. The assay does not require chemical labeling of the components and shows good sensitivity (25 pM E(2)) and wide dynamic range of more than four orders of magnitude.

Coloring in the Emotional Language of Place

ERIC Educational Resources Information Center

Haigh, Martin

2008-01-01

Making educational places more inviting to learners is a key aspect of Invitational Theory. This paper introduces a simple technique for sensitizing learners and instructors to how their environment affects their feelings and ability to learn. It describes a learning exercise that may be used to assess, evaluate and transform places, to promote…

SENSITIVITY OF NITROGEN CONCENTRATIONS IN ESTUARIES TO LOADING AND WATER RESIDENCE TIME: APPLICATION TO THE POTOMAC ESTUARY

EPA Science Inventory

We use a simple nitrogen budget model to analyze concentrations of total nitrogen (TN) in estuaries for which both nitrogen inputs and water residence time are correlated with freshwater inflow rates. While the nitrogen concentration of an estuary varies linearly with TN loading ...

UV Radiation Damage and Bacterial DNA Repair Systems

ERIC Educational Resources Information Center

Zion, Michal; Guy, Daniel; Yarom, Ruth; Slesak, Michaela

2006-01-01

This paper reports on a simple hands-on laboratory procedure for high school students in studying both radiation damage and DNA repair systems in bacteria. The sensitivity to ultra-violet (UV) radiation of both "Escherichia coli" and "Serratia marcescens" is tested by radiating them for varying time periods. Two growth temperatures are used in…

Reading Angles in Maps

ERIC Educational Resources Information Center

Izard, Véronique; O'Donnell, Evan; Spelke, Elizabeth S.

2014-01-01

Preschool children can navigate by simple geometric maps of the environment, but the nature of the geometric relations they use in map reading remains unclear. Here, children were tested specifically on their sensitivity to angle. Forty-eight children (age 47:15-53:30 months) were presented with fragments of geometric maps, in which angle sections…

Detection of Legume Protease Inhibitors by the Gel-X-ray Film Contact Print Technique

ERIC Educational Resources Information Center

Mulimani, Veerappa H.; Sudheendra, Kulkarni; Giri, Ashok P.

2002-01-01

Redgram (Cajanus cajan L.) extracts have been analyzed for the protease inhibitors using a new, sensitive, simple, and rapid method for detection of electrophoretically separated protease inhibitors. The detection involves equilibrating the gel successively in the protease assay buffer and protease solution, rinsing the gel in assay buffer, and…

Synthesis of an Epoxide Carbonylation Catalyst: Exploration of Contemporary Chemistry for Advanced Undergraduates

ERIC Educational Resources Information Center

Getzler, Yutan D. Y. L.; Schmidt, Joseph A. R.; Coates, Geoffrey W.

2005-01-01

A class of highly active, well-defined compounds for the catalytic carbonylation of epoxides and aziridines to beta-lactones and beta-lactams are introduced. The synthesis of one of the catalysts involves a simple imine condensation to form the ligand followed by air-sensitive metalation and salt metathesis steps.

SENSITIVITY ANALYSIS AND PRELIMINARY EVALUATION OF RELMAP (REGIONAL LAGRANGIAN MODEL OF AIR POLLUTION) INVOLVING FINE AND COURSE PARTICULATE MATTER

EPA Science Inventory

In response to the new, size-discriminate federal standards for Inhalable Particulate Matter, the Regional Lagrangian Model of Air Pollution (RELMAP) has been modified to include simple, linear parameterizations. As an initial step in the possible refinement, RELMAP has been subj...

Engineering Paper-Based Sensors for Zika Virus

DOE PAGES

Meagher, Robert J.; Negrete, Oscar A.; Van Rompay, Koen K.

2016-05-30

The emergence of Zika virus in Latin America has created an urgent need for new, simple yet sensitive diagnostic tests. We highlight recent work using paper-based sensors coupled with CRISPR/Cas9 to detect Zika RNA, as a new approach to rapid development and deployment of field-ready diagnostics for emerging infectious diseases.

Engineering Paper-Based Sensors for Zika Virus

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

Meagher, Robert J.; Negrete, Oscar A.; Van Rompay, Koen K.

The emergence of Zika virus in Latin America has created an urgent need for new, simple yet sensitive diagnostic tests. We highlight recent work using paper-based sensors coupled with CRISPR/Cas9 to detect Zika RNA, as a new approach to rapid development and deployment of field-ready diagnostics for emerging infectious diseases.

A System for Cooling inside a Glove Box

ERIC Educational Resources Information Center

Sanz, Martial

2010-01-01

An easy, efficient, reliable, and low-cost method of constructing a cooling system using a simple circulating pump is described. The system is employed in conjunction with an inert atmosphere glove box to achieve the synthesis of air- and moisture-sensitive compounds inside the glove box at controlled, low temperatures without contaminating the…

Blast-induced Mild Traumatic Brain Injury

DTIC Science & Technology

2010-01-01

concentration with agents such as psychostimulants, or improving compensatory strategies through cognitive- behavioral therapies. Pharmacological interventions...participate in educational activities and support groups. Some examples of general educational content include (1) compensatory strategies for impaired...or simple, ranging from electronic transmitters to trip wires, tilt switches, motion detectors, or thermal or pressure-sensitive switches. lEOs are

Development of one-step Loop-Mediated Isothermal Amplification (LAMP) for the detection of norovirus in oysters

USDA-ARS?s Scientific Manuscript database

The aim of this study was to develop a simple and rapid technique for detecting human norovirus (NoV). The loop-mediated isothermal amplification (LAMP) technique was evaluated and found to be sensitive, highly specific, and useful for routine oyster testing. Reverse transcription-LAMP (RT-LAMP) pri...

A simple, sensitive graphical method of treating thermogravimetric analysis data

Treesearch

Abraham Broido

1969-01-01

Thermogravimetric Analysis (TGA) is finding increasing utility in investigations of the pyrolysis and combustion behavior of materuals. Although a theoretical treatment of the TGA behavior of an idealized reaction is relatively straight-forward, major complications can be introduced when the reactions are complex, e.g., in the pyrolysis of cellulose, and when...

MODELING NON-PRECIPITATING CUMULUS CLOUDS AS FLOW-THROUGH-REACTOR TRANSFORMER AND VENTING TRANSPORTER OF MIXED LAYER POLLUTANTS

EPA Science Inventory

A simple diagnostic model of cumulus convective clouds is developed and used in a sensitivity study to examine the extent to which the rate of change of mixed and cloud layer pollutant concentration is influenced by vertical transport and chemical transformation processes occurri...

Development of a 3D origami multiplex electrochemical immunodevice using a nanoporous silver-paper electrode and metal ion functionalized nanoporous gold-chitosan.

PubMed

Li, Weiping; Li, Long; Li, Meng; Yu, Jinghua; Ge, Shenguang; Yan, Mei; Song, Xianrang

2013-10-25

A simple and sensitive 3D microfluidic origami multiplex electrochemical immunodevice was developed for the first time using a novel nanoporous silver modified paper working electrode as a sensor platform and different metal ion functionalized nanoporous gold-chitosan as a tracer.

A Device to Demonstrate the Principles of Photometry and Three Experiments for Its Use.

ERIC Educational Resources Information Center

Delumyea, R. Del

1987-01-01

Describes how to construct a simple photometer. Outlines experiments in which this device can be used to demonstrate basic electronic principles, the use of Beer's Law to determine the concentration of an analyte in solution, and the effect of molar absorptivity on the sensitivity of photometric procedures. (TW)

Context-Sensitive Rules and Word Naming in Italian Children

ERIC Educational Resources Information Center

Barca, Laura; Ellis, Andrew W.; Burani, Cristina

2007-01-01

The present study examines the role of orthographic complexity on Italian children's word reading. Two experiments are reported in which elementary school children (3rd and 5th graders) read aloud words containing simple or contextual letter-sound conversion rules. In Experiment 1, both groups of participants read words containing contextual rules…

Safety in the Chemical Laboratory

ERIC Educational Resources Information Center

Coffee, Robert D.

1972-01-01

The author discusses a system for establishing the relative potential of a chemical to release energy suddenly and to indicate release. This system is applicable to chemical storage and transportation. The system is based upon three simple tests requiring a minimum sample (1 go or 1 ml): (1) computation, (2) impact sensitivity, and (3) thermal…

Experiments with Charge Indicator Based on Bipolar Transistors

ERIC Educational Resources Information Center

Dvorak, Leos; Planinsic, Gorazd

2012-01-01

A simple charge indicator with bipolar transistors described recently enables us to perform a number of experiments suitable for high-school physics. Several such experiments are presented and discussed in this paper as well as some features of the indicator important for its use in schools, namely its sensitivity and robustness, i.e. the…

Peroral bioassay of nucleopolyhedrosis viruses in larvae of western spruce budworm.

Treesearch

Mauro E. Martignoni; Paul J. Iwai

1981-01-01

The relative virulence of entomopathogenic viruses and the potency of virus preparations for control of destructive insects can be estimated reliably only by means of biological assay in the target species. A simple, yet sensitive peroral bioassay procedure is described for preparations of nucleopolyhedrosis viruses pathogenic for the western spruce budworm, ...

Novel approach using DNA-RNA hybrids in RNA nanotechnology | Center for Cancer Research

Cancer.gov

Developing simple approaches to detect interactions, modifications, and cellular locations of macromolecules is essential for understanding biochemical processes. The use of protein fragment complementation assays, also called split-protein systems, is a highly sensitive approach for studying protein interactions in biological systems. In this approach, functional proteins are

Universal absolute quantification of biomolecules using element mass spectrometry and generic standards.

PubMed

Calderón-Celis, Francisco; Sanz-Medel, Alfredo; Encinar, Jorge Ruiz

2018-01-23

We present a novel and highly sensitive ICP-MS approach for absolute quantification of all important target biomolecule containing P, S, Se, As, Br, and/or I (e.g., proteins and phosphoproteins, metabolites, pesticides, drugs), under the same simple instrumental conditions and without requiring any specific and/or isotopically enriched standard.

USE OF A SIMPLE THERMALISED NEUTRON FIELD FOR QUALITY ACCEPTANCE OF WHOLE BODY TLDS.

PubMed

Gilvin, P J; Baker, S T; Eakins, J S; Tanner, R J

2016-09-01

The individual monitoring service of Public Health England (PHE) uses Harshaw™ whole-body and extremity thermoluminescent dosemeters (TLDs) with high-sensitivity lithium fluoride LiF:Mg,Cu,P, together with Harshaw 8800™ automated readers. The neutron-insensitive, (6)Li-depleted variety of TLD material is used by PHE because the service provides separate neutron and photon dosemeters. The neutron dosemeters are not sensitive to photons and vice versa Since insensitivity to neutrons is a supply requirement for TLDs, there is a need to test every new (annual) consignment for this. Because it is thermal neutrons that produce a response in (6)Li TLDs, a thermal field is needed. To this end, PHE has adopted the simple approach of sandwiching the TLDs between two ISO water-filled slab phantoms. In this arrangement, the fast neutrons from an Am-Be source are effectively thermalised. Details of the method are given, together with the results of supporting MCNP calculations and some typical results. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A simple pendulum borehole tiltmeter based on a triaxial optical-fibre displacement sensor

NASA Astrophysics Data System (ADS)

Chawah, P.; Chéry, J.; Boudin, F.; Cattoen, M.; Seat, H. C.; Plantier, G.; Lizion, F.; Sourice, A.; Bernard, P.; Brunet, C.; Boyer, D.; Gaffet, S.

2015-11-01

Sensitive instruments like strainmeters and tiltmeters are necessary for measuring slowly varying low amplitude Earth deformations. Nonetheless, laser and fibre interferometers are particularly suitable for interrogating such instruments due to their extreme precision and accuracy. In this paper, a practical design of a simple pendulum borehole tiltmeter based on laser fibre interferometric displacement sensors is presented. A prototype instrument has been constructed using welded borosilicate with a pendulum length of 0.85 m resulting in a main resonance frequency of 0.6 Hz. By implementing three coplanar extrinsic fibre Fabry-Perot interferometric probes and appropriate signal filtering, our instrument provides tilt measurements that are insensitive to parasitic deformations caused by temperature and pressure variations. This prototype has been installed in an underground facility (Rustrel, France) where results show accurate measurements of Earth strains derived from Earth and ocean tides, local hydrologic effects, as well as local and remote earthquakes. The large dynamic range and the high sensitivity of this tiltmeter render it an invaluable tool for numerous geophysical applications such as transient fault motion, volcanic strain and reservoir monitoring.

Fabrication of taste sensor for education

NASA Astrophysics Data System (ADS)

Wu, Xiao; Tahara, Yusuke; Toko, Kiyoshi; Kuriyaki, Hisao

2017-03-01

In order to solve the unconcern to usefulness of learning science among high school students in Japan, we developed a simple fabricated taste sensor with sensitivity and selectivity to each taste quality, which can be applied in science class. A commercialized Teflon membrane was used as the polymer membrane holding lipids. In addition, a non-adhesive method is considered to combine the membrane and the sensor electrode using a plastic cap which is easily accessible. The taste sensor for education fabricated in this way showed a good selectivity and sensitivity. By adjusting the composition of trioctylmethylammonium chloride (TOMA) and phosphoric acid di(2-ethylhexyl) ester (PAEE) included in lipid solution, we improved the selectivity of this simple taste sensor to saltiness and sourness. To verify this taste sensor as a useful science teaching material for science class, we applied this taste sensor into a science class for university students. By comparing the results between the sensory test and the sensor response, humans taste showed the same tendency just as the sensor response, which proved the sensor as a useful teaching material for science class.

Development of a sensitive high-performance liquid chromatographic method with simple extraction for simultaneous determination of huperzine A and huperzine B in the species containing lycopodium alkaloids.

PubMed

Zhang, Yanqing; Xie, Junbo; Chen, Wen-Qian; Zhou, Tian-Yan; Lu, Wei

2009-01-01

A sensitive HPLC method with simple extraction was developed for simultaneous determination of huperzine A (HupA) and huperzine B (HupB) in Huperzia serrata, H. crispata, H. miyoshiana, and Lycopodiastrum casuarinoides. In order to avoid conventional multiple-step and time-consuming sample preparation methods, direct reflux extraction with alkaline chloroform was adopted. The quantitative determination was conducted by reversed-phase HPLC with a photodiode array detector set at 308 nm. Separation was performed on a Luna C18 column (250 x 4.6 mm id, 5 microm) with methanol-0.2% aqueous acetic acid (18 + 82, v/v) mobile phase. The method was validated for accuracy, reproducibility, precision, and limits of detection and quantification. Quantification of the two active compounds in the samples was performed by this newly developed method, and the content of HupA and HupB varied substantially among four different species. The satisfactory results indicated that the developed method can readily be utilized for quality control of the species of Huperziaceae and Lycopodiaceae containing the two compounds.

Custom-Made Finger Guard to Prevent Wire-Stick Injury to the Operator's Finger while Performing Intermaxillary Fixation.

PubMed

Kumaresan, Ramesh; Ponnusami, Karthikeyan; Karthikeyan, Priyadarshini

2014-12-01

The treatment of maxillofacial fractures involves different methods from bandages and splinting to methods of open reduction and internal fixation and usually requires control of the dental occlusion with the help of intermaxillary fixation (IMF). Different wiring techniques have been used to aid in IMF including placement of custom-made arch bars, eyelet etc. However, these wiring techniques are with a constant danger of trauma to the surgeon's fingers by their sharp ends. Though there exist a variety of commercially available barrier products and customized techniques to prevent wire-stick injury, cost factor, touch sensitivity, and comfort aspect restrain their acquirement and exploit. This technical note describes the construction of a simple and economical finger guard made of soft thermoplastic material that provides an added protection to fingers from wire-stick type injuries, and its flexible nature permits a comfortable finger flexion movement and acceptable touch sensitivity. This is a simple, economical, reusable puncture, and cut-resistance figure guard by which we can avoid wire-stick type injury to the operator's fingers during wiring technique.

Swimming micro-robot powered by stimuli-sensitive gel

NASA Astrophysics Data System (ADS)

Masoud, Hassan; Alexeev, Alexander

2012-11-01

Using three-dimensional computer simulations, we design a simple maneuverable micro-swimmer that can self-propel and navigate in highly viscous (low Reynolds-number) environments. Our simple swimmer consists of a cubic gel body which periodically changes volume in response to external stimuli, two rigid rectangular flaps attached to the opposite sides of the gel body, and a flexible steering flap at the front end of the swimmer. The stimuli-sensitive body undergoes periodic expansions (swelling) and contractions (deswelling) leading to a time-irreversible beating motion of the propulsive flaps that propel the micro-swimmer. Thus, the responsive gel body acts as an ``engine'' actuating the motion of the swimmer. We examine how the swimming speed depends on the gel and flap properties. We also probe how the swimmer trajectory can be changed using a responsive steering flap whose curvature is controlled by an external stimulus. We show that the turning occurs due to steering flap bending and periodic beating. Furthermore, our simulations reveal that the turning direction can be regulated by changing the intensity of external stimulus.

Entanglement-Assisted Weak Value Amplification

NASA Astrophysics Data System (ADS)

Pang, Shengshi; Dressel, Justin; Brun, Todd A.

2014-07-01

Large weak values have been used to amplify the sensitivity of a linear response signal for detecting changes in a small parameter, which has also enabled a simple method for precise parameter estimation. However, producing a large weak value requires a low postselection probability for an ancilla degree of freedom, which limits the utility of the technique. We propose an improvement to this method that uses entanglement to increase the efficiency. We show that by entangling and postselecting n ancillas, the postselection probability can be increased by a factor of n while keeping the weak value fixed (compared to n uncorrelated attempts with one ancilla), which is the optimal scaling with n that is expected from quantum metrology. Furthermore, we show the surprising result that the quantum Fisher information about the detected parameter can be almost entirely preserved in the postselected state, which allows the sensitive estimation to approximately saturate the relevant quantum Cramér-Rao bound. To illustrate this protocol we provide simple quantum circuits that can be implemented using current experimental realizations of three entangled qubits.

A label-free colorimetric aptasensor for simple, sensitive and selective detection of Pt (II) based on platinum (II)-oligonucleotide coordination induced gold nanoparticles aggregation.

PubMed

Fan, Daoqing; Zhai, Qingfeng; Zhou, Weijun; Zhu, Xiaoqing; Wang, Erkang; Dong, Shaojun

2016-11-15

Herein, a gold nanoparticles (AuNPs) based label-free colorimetric aptasensor for simple, sensitive and selective detection of Pt (II) was constructed for the first time. Four bases (G-G mismatch) mismatched streptavidin aptamer (MSAA) was used to protect AuNPs from salt-induced aggregation and recognize Pt (II) specifically. Only in the presence of Pt (II), coordination occurs between G-G bases and Pt (II), leading to the activation of streptavidin aptamer. Streptavidin coated magnetic beads (MBs) were used as separation agent to separate Pt (II)-coordinated MSAA. The residual less amount of MSAA could not efficiently protect AuNPs anymore and aggregation of AuNPs will produce a colorimetric product. With the addition of Pt (II), a pale purple-to-blue color variation could be observed by the naked eye. A detection limit of 150nM and a linear range from 0.6μM to 12.5μM for Pt (II) could be achieved without any amplification. Copyright © 2016 Elsevier B.V. All rights reserved.

Simple and rapid silver nanoparticles based antioxidant capacity assays: Reactivity study for phenolic compounds.

PubMed

Della Pelle, Flavio; Scroccarello, Annalisa; Sergi, Manuel; Mascini, Marcello; Del Carlo, Michele; Compagnone, Dario

2018-08-01

A single-step, rapid (10 min), sensitive silver nanoparticles (AgNPs) based spectrophotometric method for antioxidant capacity (AOC) assay has been developed. The assay is based on the ability of natural polyphenols to reduce Ag(I) and stabilize the produced AgNPs(0) at room temperature. Localized surface plasmon resonance (LSPR) of AgNPs at ≈420 nm is then measured. Using different conditions of pH (8.4) and temperature (45 °C) a further assay based on the production of AgNPs with selectivity for flavonols was also developed. The reactivity of the two AgNPs based assays vs. 15 polyphenols belonging to different chemical classes and 9 different samples has been studied and compared with ABTS, Folin and AuNPs based methods for AOC. The proposed assays had good reproducibility (RSD ≤ 13) and are simple, sensitive and cost effective. Moreover, used in conjunction with the classical AOC assays, can improve the information on the polyphenolic pool of food samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

A simple and highly sensitive spectroscopic fluorescence-detection system for multi-channel plastic-microchip electrophoresis based on side-entry laser-beam zigzag irradiation.

PubMed

Anazawa, Takashi; Uchiho, Yuichi; Yokoi, Takahide; Chalkidis, George; Yamazaki, Motohiro

2017-06-27

A five-color fluorescence-detection system for eight-channel plastic-microchip electrophoresis was developed. In the eight channels (with effective electrophoretic lengths of 10 cm), single-stranded DNA fragments were separated (with single-base resolution up to 300 bases within 10 min), and seventeen-loci STR genotyping for forensic human identification was successfully demonstrated. In the system, a side-entry laser beam is passed through the eight channels (eight A channels), with alternately arrayed seven sacrificial channels (seven B channels), by a technique called "side-entry laser-beam zigzag irradiation." Laser-induced fluorescence from the eight A channels and Raman-scattered light from the seven B channels are then simultaneously, uniformly, and spectroscopically detected, in the direction perpendicular to the channel array plane, through a transmission grating and a CCD camera. The system is therefore simple and highly sensitive. Because the microchip is fabricated by plastic-injection molding, it is inexpensive and disposable and thus suitable for actual use in various fields.

Highly sensitive fluorescence and SERS detection of azide through a simple click reaction of 8-chloroquinoline and phenylacetylene.

PubMed

Zeng, Qing; Ye, Lingling; Ma, Lu; Yin, Wenqing; Li, Tingsheng; Liang, Aihui; Jiang, Zhiliang

2015-05-01

In 0.19 mol/L acetic acid (HAc), a click reaction of 8-chloroquinoline/azide/phenylacetylene take places in aqueous solution without Cu(I) as a catalyst. 8-Chloroquinoline (CQN) exhibited a strong fluorescence peak at 430 nm that was quenched linearly as the concentration of azide increased from 20 to 1000 ng/mL. This quenching was due to consumption of CQN in the click reaction and a decrease in the number of efficiently excited photons due to the presence of triazole-quinoline ramification molecules with strong hydrophobicity. Using blue nanosilver sol as the substrate, CQN absorbed onto the surface of nanosilver particles, showing a strong surface-enhanced Raman scattering (SERS) peak at 1585 cm(-1) that decreased linearly as the azide concentration increased from 8 to 500 ng/mL; the detection limit was 4 ng/mL. Thus, two new, simple and sensitive fluorescence and SERS methods have been developed for the determination of azide via the click reaction. Copyright © 2014 John Wiley & Sons, Ltd.

Quality assurance for high dose rate brachytherapy treatment planning optimization: using a simple optimization to verify a complex optimization

NASA Astrophysics Data System (ADS)

Deufel, Christopher L.; Furutani, Keith M.

2014-02-01

As dose optimization for high dose rate brachytherapy becomes more complex, it becomes increasingly important to have a means of verifying that optimization results are reasonable. A method is presented for using a simple optimization as quality assurance for the more complex optimization algorithms typically found in commercial brachytherapy treatment planning systems. Quality assurance tests may be performed during commissioning, at regular intervals, and/or on a patient specific basis. A simple optimization method is provided that optimizes conformal target coverage using an exact, variance-based, algebraic approach. Metrics such as dose volume histogram, conformality index, and total reference air kerma agree closely between simple and complex optimizations for breast, cervix, prostate, and planar applicators. The simple optimization is shown to be a sensitive measure for identifying failures in a commercial treatment planning system that are possibly due to operator error or weaknesses in planning system optimization algorithms. Results from the simple optimization are surprisingly similar to the results from a more complex, commercial optimization for several clinical applications. This suggests that there are only modest gains to be made from making brachytherapy optimization more complex. The improvements expected from sophisticated linear optimizations, such as PARETO methods, will largely be in making systems more user friendly and efficient, rather than in finding dramatically better source strength distributions.

A Label-Free Aptasensor for Ochratoxin a Detection Based on the Structure Switch of Aptamer.

PubMed

Liu, Feng; Ding, Ailing; Zheng, Jiushang; Chen, Jiucun; Wang, Bin

2018-06-01

A label-free sensing platform is developed based on switching the structure of aptamer for highly sensitive and selective fluorescence detection of ochratoxin A (OTA). OTA induces the structure of aptamer, transforms into G-quadruplex and produces strong fluorescence in the presence of zinc(II)-protoporphyrin IX probe due to the specific bind to G-quadruplex. The simple method exhibits high sensitivity towards OTA with a detection limit of 0.03 nM and excellent selectivity over other mycotoxins. In addition, the successful detection of OTA in real samples represents a promising application in food safety.

An Incidence Loss Model for Wave Rotors with Axially Aligned Passages

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.

1998-01-01

A simple mathematical model is described to account for the losses incurred when the flow in the duct (port) of a wave rotor is not aligned with the passages. The model, specifically for wave rotors with axially aligned passages, describes a loss mechanism which is sensitive to incident flow angle and Mach number. Implementation of the model in a one-dimensional CFD based wave rotor simulation is presented. Comparisons with limited experimental results are consistent with the model. Sensitivity studies are presented which highlight the significance of the incidence loss relative to other loss mechanisms in the wave rotor.