Poly(4-vinylphenylboronic acid) functionalized polypyrrole/graphene oxide nanosheets for simultaneous electrochemical determination of catechol and hydroquinone

NASA Astrophysics Data System (ADS)

Mao, Hui; Liu, Meihong; Cao, Zhenqian; Ji, Chunguang; Sun, Ying; Liu, Daliang; Wu, Shuyao; Zhang, Yu; Song, Xi-Ming

2017-10-01

Novel poly(4-vinylphenylboronic acid) (P4VPBA) functionalized polypyrrole/graphene oxide (PPy/GO) nanosheets, which combined the advantages of GO, PPy and PBA groups, were successfully prepared by a simple polymerization of 4-vinylphenylboronic acid (4VPBA) on the surface of pre-treated PPy/GO containing vinyl groups. Because of the synergistic effects of GO with excellent 2D structures and large surface area, PPy with good electronic conductivity and PBA with high recognition capability, P4VPBA/PPy/GO modified glassy carbon electrode presented excellent electrochemical sensing capabilities toward catechol (CC) and hydroquinone (HQ) with good stability, high sensitivity and selectivity, especially giving a large anodic peak potential difference between CC and HQ enough to well distinguish and simultaneously determine the two dihydroxybenzene isomers in their mixture. It is found that PBA groups on the surface of P4VPBA/PPy/GO nanosheets played an essential role for the discrimination and simultaneous electrochemical determination of CC and HQ, which may be due to the selective formation of stable cyclic esters by the covalent interaction between PBA groups and related molecules with a cis-diol in an alkaline aqueous solution. Therefore, P4VPBA/PPy/GO nanosheets can act as a good electrode material for building a steady electrochemical sensor for detecting the two dihydroxybenzene isomers with high sensitivity and selectivity.

Ni-Co bimetal nanowires filled multiwalled carbon nanotubes for the highly sensitive and selective non-enzymatic glucose sensor applications

PubMed Central

Ramachandran, K.; Raj kumar, T.; Babu, K. Justice; Gnana kumar, G.

2016-01-01

The facile, time and cost efficient and environmental benign approach has been developed for the preparation of Nickel (Ni)-Cobalt (Co) alloy nanowires filled multiwalled carbon nanotubes (MWCNTs) with the aid of mesoporous silica nanoparticles (MSN)/Ni-Co catalyst. The controlled incorporation of Ni-Co nanostructures in the three dimensional (3D) pore structures of MSN yielded the catalytically active system for the MWCNT growth. The inner surface of MWCNTs was quasi-continuously filled with face-centered cubic (fcc) structured Ni-Co nanowires. The as-prepared nanostructures were exploited as non-enzymatic electrochemical sensor probes for the reliable detection of glucose. The electrochemical measurements illustrated that the fabricated sensor exhibited an excellent electrochemical performance toward glucose oxidation with a high sensitivity of 0.695 mA mM−1 cm−2, low detection limit of 1.2 μM, a wide linear range from 5 μM–10 mM and good selectivity. The unprecedented electrochemical performances obtained for the prepared nanocomposite are purely attributed to the synergistic effects of Ni-Co nanowires and MWCNTs. The constructed facile, selective and sensitive glucose sensor has also endowed its reliability in analyzing the human serum samples, which wide opened the new findings for exploring the novel nanostructures based glucose sensor devices with affordable cost and good stability. PMID:27833123

Ni-Co bimetal nanowires filled multiwalled carbon nanotubes for the highly sensitive and selective non-enzymatic glucose sensor applications

NASA Astrophysics Data System (ADS)

Ramachandran, K.; Raj Kumar, T.; Babu, K. Justice; Gnana Kumar, G.

2016-11-01

The facile, time and cost efficient and environmental benign approach has been developed for the preparation of Nickel (Ni)-Cobalt (Co) alloy nanowires filled multiwalled carbon nanotubes (MWCNTs) with the aid of mesoporous silica nanoparticles (MSN)/Ni-Co catalyst. The controlled incorporation of Ni-Co nanostructures in the three dimensional (3D) pore structures of MSN yielded the catalytically active system for the MWCNT growth. The inner surface of MWCNTs was quasi-continuously filled with face-centered cubic (fcc) structured Ni-Co nanowires. The as-prepared nanostructures were exploited as non-enzymatic electrochemical sensor probes for the reliable detection of glucose. The electrochemical measurements illustrated that the fabricated sensor exhibited an excellent electrochemical performance toward glucose oxidation with a high sensitivity of 0.695 mA mM-1 cm-2, low detection limit of 1.2 μM, a wide linear range from 5 μM-10 mM and good selectivity. The unprecedented electrochemical performances obtained for the prepared nanocomposite are purely attributed to the synergistic effects of Ni-Co nanowires and MWCNTs. The constructed facile, selective and sensitive glucose sensor has also endowed its reliability in analyzing the human serum samples, which wide opened the new findings for exploring the novel nanostructures based glucose sensor devices with affordable cost and good stability.

Safer energetic materials by a nanotechnological approach

NASA Astrophysics Data System (ADS)

Siegert, Benny; Comet, Marc; Spitzer, Denis

2011-09-01

Energetic materials - explosives, thermites, populsive powders - are used in a variety of military and civilian applications. Their mechanical and electrostatic sensitivity is high in many cases, which can lead to accidents during handling and transport. These considerations limit the practical use of some energetic materials despite their good performance. For industrial applications, safety is one of the main criteria for selecting energetic materials. The sensitivity has been regarded as an intrinsic property of a substance for a long time. However, in recent years, several approaches to lower the sensitivity of a given substance, using nanotechnology and materials engineering, have been described. This feature article gives an overview over ways to prepare energetic (nano-)materials with a lower sensitivity.Energetic materials - explosives, thermites, populsive powders - are used in a variety of military and civilian applications. Their mechanical and electrostatic sensitivity is high in many cases, which can lead to accidents during handling and transport. These considerations limit the practical use of some energetic materials despite their good performance. For industrial applications, safety is one of the main criteria for selecting energetic materials. The sensitivity has been regarded as an intrinsic property of a substance for a long time. However, in recent years, several approaches to lower the sensitivity of a given substance, using nanotechnology and materials engineering, have been described. This feature article gives an overview over ways to prepare energetic (nano-)materials with a lower sensitivity. Electronic supplementary information (ESI) available: Experimental details for the preparation of the V2O5@CNF/Al nanothermite; X-ray diffractogram of the V2O5@CNF/Al combustion residue; installation instructions and source code for the nt-timeline program. See DOI: 10.1039/c1nr10292c

"Sign-on/off" sensing interface design and fabrication for propyl gallate recognition and sensitive detection.

PubMed

Dai, Yunlong; Li, Xueyan; Fan, Limei; Lu, Xiaojing; Kan, Xianwen

2016-12-15

A new strategy based on sign-on and sign-off was proposed for propyl gallate (PG) determination by an electrochemical sensor. The successively modified poly(thionine) (PTH) and molecular imprinted polymer (MIP) showed an obvious electrocatalysis and a good recognition toward PG, respectively. Furthermore, the rebound PG molecules in imprinted cavities not only were oxidized but also blocked the electron transmission channels for PTH redox. Thus, a sign-on from PG current and a sign-off from PTH current were combined as a dual-sign for PG detection. Meanwhile, the modified MIP endowed the sensor with recognition capacity. The electrochemical experimental results demonstrated that the prepared sensor possessed good selectivity and high sensitivity. A linear ranging from 5.0×10(-8) to 1.0×10(-4)mol/L for PG detection was obtained with a limit of detection of 2.4×10(-8)mol/L. And the sensor has been applied to analyze PG in real samples with satisfactory results. The simple, low cost, and effective strategy reported here can be further used to prepare electrochemical sensors for other compounds selective recognition and sensitive detection. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydrothermally grown α-MnO2 interlocked mesoporous micro-cubes of several nanocrystals as selective and sensitive nitrogen dioxide chemoresistive gas sensors

NASA Astrophysics Data System (ADS)

Shinde, Pritamkumar V.; Xia, Qi Xun; Ghule, Balaji G.; Shinde, Nanasaheb M.; Seonghee, Jeong; Kim, Kwang Ho; Mane, Rajaram S.

2018-06-01

The interesting and multifunctional properties of alpha-manganese dioxide (α-MnO2) are considered to be highly sensitive and selective to nitrogen dioxide (NO2) chemresistive gas sensors. The α-MnO2 mesoporous interlocked micro-cubes composed of several interconnected nanocrystals synthesized by a facile and low-cost hydrothermal method on soda-lime glass substrate are envisaged as selective and sensitive NO2 gas sensors. Phase-purity and surface area with pore-size distribution are initially screened. The three-dimensional α-MnO2 mesoporous-cube-based gas sensors tested for NO2 gas from room-temperature (27 °C) to 250 °C have demonstrated 33% response for 100 ppm NO2 levels at 150 °C. The response and recovery time values of the α-MnO2 sensor are found to be 26 s and recovery 91 s, respectively, with high selectivity, good sensitivity, and considerable chemical and environmental stabilities, confirming the gas sensor applications potentiality of α-MnO2 morphology which is a combination of interlocked mesoporous micro-cubes and well-connected nanocrystals.

Molecularly imprinted fluorescent hollow nanoparticles as sensors for rapid and efficient detection λ-cyhalothrin in environmental water.

PubMed

Wang, Jixiang; Qiu, Hao; Shen, Hongqiang; Pan, Jianming; Dai, Xiaohui; Yan, Yongsheng; Pan, Guoqing; Sellergren, Börje

2016-11-15

Molecularly imprinted fluorescent polymers have shown great promise in biological or chemical separations and detections, due to their high stability, selectivity and sensitivity. In this work, molecularly imprinted fluorescent hollow nanoparticles, which could rapidly and efficiently detect λ-cyhalothrin (a toxic insecticide) in water samples, was reported. The molecularly imprinted fluorescent sensor showed excellent sensitivity (the limit of detection low to 10.26nM), rapid detection rate (quantitative detection of λ-cyhalothrin within 8min), regeneration ability (maintaining good fluorescence properties after 8 cycling operation) and appreciable selectivity over several structural analogs. Moreover, the fluorescent sensor was further used to detect λ-cyhalothrin in real samples form the Beijing-Hangzhou Grand Canal Water. Despite the relatively complex components of the environmental water, the molecularly imprinted fluorescent hollow nanosensor still showed good recovery, clearly demonstrating the potential value of this smart sensor nanomaterial in environmental monitoring. Copyright © 2016 Elsevier B.V. All rights reserved.

Theoretical studies on effective metal-to-ligand charge transfer characteristics of novel ruthenium dyes for dye sensitized solar cells.

PubMed

Wang, Huei-Tang; Taufany, Fadlilatul; Nachimuthu, Santhanamoorthi; Jiang, Jyh-Chiang

2014-05-01

The development of ruthenium dye-sensitizers with highly effective metal-to-ligand charge transfer (MLCT) characteristics and narrowed transition energy gaps are essential for the new generation of dye-sensitized solar cells. Here, we designed a novel anchoring ligand by inserting the cyanovinyl-branches inside the anchoring ligands of selected highly efficient dye-sensitizers and studied their intrinsic optical properties using theoretical methods. Our calculated results show that the designed ruthenium dyes provide good performances as sensitizers compared to the selected efficient dyes, because of their red-shift in the UV-visible absorption spectra with an increase in the absorption intensity, smaller energy gaps and thereby enhancing MLCT transitions. We found that, the designed anchoring ligand acts as an efficient "electron-acceptor" which boosts electron-transfer from a -NCS ligand to this ligand via a Ru-bridge, thus providing a way to lower the transition energy gap and enhance the MLCT transitions.

Preparation of highly stable fullerene C60 decorated graphene oxide nanocomposite and its sensitive electrochemical detection of dopamine in rat brain and pharmaceutical samples.

PubMed

Thirumalraj, Balamurugan; Palanisamy, Selvakumar; Chen, Shen-Ming; Lou, Bih-Show

2016-01-15

The research community has continuously paid much attention on the preparation of hybrid of carbon nanomaterials owing to combine their unique properties. Herein, we report the preparation of highly stable fullerene C60 (C60) wrapped graphene oxide (GO) nanocomposite by using a simple sonication method. The fabricated GO-C60 nanocomposite modified glassy carbon electrode shows a good sensitivity and lower oxidation overpotential towards dopamine (DA) than that of pristine GO and C60. The fabricated sensor detects the DA in the linear response range of 0.02-73.5μM. The limit of detection is estimated to be 0.008μM based on 3σ with a sensitivity of 4.23μAμM(-1)cm(-2). The fabricated sensor also exhibits other features such as good selectivity, stability, reproducibility and repeatability. The proposed sensor exhibits good practicality towards the detection of DA in rat brain and commercial DA injection samples. Copyright © 2015 Elsevier Inc. All rights reserved.

[Surgical treatment of gynecomastia: an algorithm].

PubMed

Wolter, A; Scholz, T; Diedrichson, J; Liebau, J

2013-04-01

Gynecomastia is a persistent benign uni- or bilateral enlargement of the male breast ranging from small to excessive findings with marked skin redundancy. In this paper we introduce an algorithm to facilitate the selection of the appropriate surgical technique according to the presented morphological aspects. The records of 118 patients (217 breasts) with gynecomastia from 01/2009 to 08/2012 were retrospectively reviewed. The authors conducted three different surgical techniques depending on four severity grades. The outcome parameters complication rate, patient satisfaction with the aesthetic result, nipple sensitivity and the need to re-operate were observed and related to the employed technique. In 167 (77%) breasts with moderate breast enlargement without skin redundancy (Grade I-IIa by Simon's classification) a subcutaneous semicircular periareolar mastectomy was performed in combination with water-jet assisted liposuction. In 40 (18%) breasts with skin redundancy (Grade IIb) a circumferential mastopexy was performed additionally. An inferior pedicled mammaplasty was used in 10 (5%) severe cases (Grade III). Complication rate was 4.1%. Surgical corrections were necessary in 17 breasts (7.8%). The patient survey revealed a high satisfaction level: 88% of the patients rated the aesthetic results as "very good" or "good", nipple sensitivity was rated as "very good" or "good" by 83%. Surgical treatment of gynecomastia should ensure minimal scarring while respecting the aesthetic unit. The selection of the appropriate surgical method depends on the severity grade, the presence of skin redundancy and the volume of the male breast glandular tissue. The presented algorithm rarely leads to complications, is simple to perform and shows a high satisfaction rate and a preservation of the nipple sensitivity. © Georg Thieme Verlag KG Stuttgart · New York.

An electrochemical dopamine sensor based on the ZnO/CuO nanohybrid structures.

PubMed

Khun, K; Ibupoto, Z H; Liu, X; Mansor, N A; Turner, A P F; Beni, V; Willander, M

2014-09-01

The selective detection of dopamine (DA) is of great importance in the modern medicine because dopamine is one of the main regulators in human behaviour. In this study, ZnO/CuO nanohybrid structures, grown on the gold coated glass substrate, have been investigated as a novel electrode material for the electrochemical detection of dopamine. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were used for the material characterization and the obtained results are in good agreement. The selective determination of dopamine was demonstrated by cyclic voltammetry (CV) and amperometric experiments. The amperometric response was linear for dopamine concentrations between 1.0 x 10(-3) and 8.0 mM with a sensitivity of 90.9 μA mM(-1) cm(-2). The proposed dopamine biosensor is very stable, selective over common interferents as glucose, uric acid and ascorbic acid, and also good reproducibility was observed for seven electrodes. Moreover, the dopamine sensor exhibited a fast response time of less than 10 s. The wide range and acceptable sensitivity of the presented dopamine sensor provide the possible application in analysing the dopamine from the real samples.

Enhancement of NH3 Gas Sensitivity at Room Temperature by Carbon Nanotube-Based Sensor Coated with Co Nanoparticles

PubMed Central

Nguyen, Lich Quang; Phan, Pho Quoc; Duong, Huyen Ngoc; Nguyen, Chien Duc; Nguyen, Lam Huu

2013-01-01

Multi-walled carbon nanotube (MWCNT) film has been fabricated onto Pt-patterned alumina substrates using the chemical vapor deposition method for NH3 gas sensing applications. The MWCNT-based sensor is sensitive to NH3 gas at room temperature. Nanoclusters of Co catalysts have been sputtered on the surface of the MWCNT film to enhance gas sensitivity with respect to unfunctionalized CNT films. The gas sensitivity of Co-functionalized MWCNT-based gas sensors is thus significantly improved. The sensor exhibits good repeatability and high selectivity towards NH3, compared with alcohol and LPG. PMID:23364198

Humidity sensor based on intracavity sensing of fiber ring laser

NASA Astrophysics Data System (ADS)

Shi, Jia; Xu, Wei; Xu, Degang; Wang, Yuye; Zhang, Chao; Yan, Chao; Yan, Dexian; He, Yixin; Tang, Longhuang; Zhang, Weihong; Yao, Jianquan

2017-10-01

A humidity sensor based on the intracavity sensing of a fiber ring laser is proposed and experimentally demonstrated. In the fiber ring laser, a humidity-sensitive fiber-optic multimode interferometer (MMI), fabricated by the single-mode-no-core-single-mode (SNCS) fiber coated with Agarose, works as the wavelength-selective filter for intracavity wavelength-modulated humidity sensing. The experiment shows that the lasing wavelength of the fiber laser has a good linear response to ambient humidity from 35%RH to 95%RH. The humidity sensitivity of -68 pm/%RH is obtained with a narrow 3 dB bandwidth less than 0.09 nm and a high signal-to-noise ratio (SNR)  ˜60 dB. The time response of the sensor has been measured to be as fast as 93 ms. The proposed sensor possesses a good stability and low temperature cross-sensitivity.

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

PubMed

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

2014-03-15

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

Identification of precision treatment strategies for relapsed/refractory multiple myeloma by functional drug sensitivity testing.

PubMed

Majumder, Muntasir Mamun; Silvennoinen, Raija; Anttila, Pekka; Tamborero, David; Eldfors, Samuli; Yadav, Bhagwan; Karjalainen, Riikka; Kuusanmäki, Heikki; Lievonen, Juha; Parsons, Alun; Suvela, Minna; Jantunen, Esa; Porkka, Kimmo; Heckman, Caroline A

2017-08-22

Novel agents have increased survival of multiple myeloma (MM) patients, however high-risk and relapsed/refractory patients remain challenging to treat and their outcome is poor. To identify novel therapies and aid treatment selection for MM, we assessed the ex vivo sensitivity of 50 MM patient samples to 308 approved and investigational drugs. With the results we i) classified patients based on their ex vivo drug response profile; ii) identified and matched potential drug candidates to recurrent cytogenetic alterations; and iii) correlated ex vivo drug sensitivity to patient outcome. Based on their drug sensitivity profiles, MM patients were stratified into four distinct subgroups with varied survival outcomes. Patients with progressive disease and poor survival clustered in a drug response group exhibiting high sensitivity to signal transduction inhibitors. Del(17p) positive samples were resistant to most drugs tested with the exception of histone deacetylase and BCL2 inhibitors. Samples positive for t(4;14) were highly sensitive to immunomodulatory drugs, proteasome inhibitors and several targeted drugs. Three patients treated based on the ex vivo results showed good response to the selected treatments. Our results demonstrate that ex vivo drug testing may potentially be applied to optimize treatment selection and achieve therapeutic benefit for relapsed/refractory MM.

Synthesis of Novel CuO Nanosheets and Their Non-Enzymatic Glucose Sensing Applications

PubMed Central

Ibupoto, Zafar Hussain; Khun, Kimleang; Beni, Valerio; Liu, Xianjie; Willander, Magnus

2013-01-01

In this study, we have developed a sensitive and selective glucose sensor using novel CuO nanosheets which were grown on a gold coated glass substrate by a low temperature growth method. X-ray differaction (XRD) and scanning electron microscopy (SEM) techniques were used for the structural characterization of CuO nanostructures. CuO nanosheets are highly dense, uniform, and exhibited good crystalline array structure. X-ray photoelectron spectroscopy (XPS) technique was applied for the study of chemical composition of CuO nanosheets and the obtained information demonstrated pure phase CuO nanosheets. The novel CuO nanosheets were employed for the development of a sensitive and selective non-enzymatic glucose sensor. The measured sensitivity and a correlation coefficient are in order 5.20 × 102 μA/mMcm2 and 0.998, respectively. The proposed sensor is associated with several advantages such as low cost, simplicity, high stability, reproducibility and selectivity for the quick detection of glucose. PMID:23787727

Synthesis of novel CuO nanosheets and their non-enzymatic glucose sensing applications.

PubMed

Ibupoto, Zafar Hussain; Khun, Kimleang; Beni, Valerio; Liu, Xianjie; Willander, Magnus

2013-06-20

In this study, we have developed a sensitive and selective glucose sensor using novel CuO nanosheets which were grown on a gold coated glass substrate by a low temperature growth method. X-ray differaction (XRD) and scanning electron microscopy (SEM) techniques were used for the structural characterization of CuO nanostructures. CuO nanosheets are highly dense, uniform, and exhibited good crystalline array structure. X-ray photoelectron spectroscopy (XPS) technique was applied for the study of chemical composition of CuO nanosheets and the obtained information demonstrated pure phase CuO nanosheets. The novel CuO nanosheets were employed for the development of a sensitive and selective non-enzymatic glucose sensor. The measured sensitivity and a correlation coefficient are in order 5.20 × 10² µA/mMcm² and 0.998, respectively. The proposed sensor is associated with several advantages such as low cost, simplicity, high stability, reproducibility and selectivity for the quick detection of glucose.

Enhanced photoelectrochemical aptasensing platform based on exciton energy transfer between CdSeTe alloyed quantum dots and SiO2@Au nanocomposites.

PubMed

Fan, Gao-Chao; Zhu, Hua; Shen, Qingming; Han, Li; Zhao, Ming; Zhang, Jian-Rong; Zhu, Jun-Jie

2015-04-25

High-efficient exciton energy transfer between CdSeTe alloyed quantum dots and SiO2@Au nanocomposites was applied to develop an enhanced photoelectrochemical aptasensing platform with ultrahigh sensitivity, good selectivity, reproducibility and stability.

A fluorescent turn-on H2S-responsive probe: design, synthesis and application.

PubMed

Zhang, Yufeng; Chen, Haiyan; Chen, Dan; Wu, Di; Chen, Xiaoqiang; Liu, Sheng Hua; Yin, Jun

2015-10-14

Hydrogen sulfide (H2S) is considered as the third signaling molecule in vivo and it plays an important role in various physiological processes and pathological processes in vivo, such as vasodilation, apoptosis, neurotransmission, ischemia/reperfusion-induced injury, insulin secretion and inflammation. Developing a highly selective and sensitive method that can detect H2S in the biological system is very important. In this work, a colorimetric and "turn-on" fluorescent probe is developed. Furthermore, this probe displays a highly selective response to H2S in aqueous solution and possesses good capability for bioimaging H2S without interference in living cells. The results suggest that a H2S-selective probe has good water-solubility, biocompatibility and cell-penetrability and can serve as an efficient tool for probing H2S in the cell level.

A front end readout electronics ASIC chip for position sensitive solid state detectors

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

Kravis, S.D.; Tuemer, T.O.; Visser, G.J.

1998-12-31

A mixed signal Application Specific Integrated Circuit (ASIC) chip for front end readout electronics of position sensitive solid state detectors has been manufactured. It is called RENA (Readout Electronics for Nuclear Applications). This chip can be used for both medical and industrial imaging of X-rays and gamma rays. The RENA chip is a monolithic integrated circuit and has 32 channels with low noise high input impedance charge sensitive amplifiers. It works in pulse counting mode with good energy resolution. It also has a self triggering output which is essential for nuclear applications when the incident radiation arrives at random. Different,more » externally selectable, operational modes that includes a sparse readout mode is available to increase data throughput. It also has externally selectable shaping (peaking) times.« less

A framework for risk assessment and decision-making strategies in dangerous good transportation.

PubMed

Fabiano, B; Currò, F; Palazzi, E; Pastorino, R

2002-07-01

The risk from dangerous goods transport by road and strategies for selecting road load/routes are faced in this paper, by developing an original site-oriented framework of general applicability at local level. A realistic evaluation of the frequency must take into account on one side inherent factors (e.g. tunnels, rail bridges, bend radii, slope, characteristics of neighborhood, etc.) on the other side factors correlated to the traffic conditions (e.g. dangerous goods trucks, etc.). Field data were collected on the selected highway, by systematic investigation, providing input data for a database reporting tendencies and intrinsic parameter/site-oriented statistics. The developed technique was applied to a pilot area, considering both the individual risk and societal risk and making reference to flammable and explosive scenarios. In this way, a risk assessment, sensitive to route features and population exposed, is proposed, so that the overall uncertainties in risk analysis can be lowered.

Twenty natural organic pigments for application in dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Castillo, D.; Sánchez Juárez, A.; Espinosa Tapia, S.; Guaman, A.; Obregón Calderón, D.

2016-09-01

In this work we present the results of a study of twenty natural pigments obtained from plants and insects from southern Ecuador. Many of them will be considered as a potential natural sensitizer for the construction of DSSCs. The results indicate that these pigments have a good performance in the absorbance and wavelength spectra. Were selected four best pigments for the construction of DSSCs, Rumex tolimensis Wedd, Raphanus sativus, Hibiscus sabdariffa, and Prunus serótina, however the conversion efficiency is lower than 1%.

Gold nanoparticle-sensitized quartz crystal microbalance sensor for rapid and highly selective determination of Cu(II) ions.

PubMed

Jin, Yulong; Huang, Yanyan; Liu, Guoquan; Zhao, Rui

2013-09-21

A novel quartz crystal microbalance (QCM) sensor for rapid, highly selective and sensitive detection of copper ions was developed. As a signal amplifier, gold nanoparticles (Au NPs) were self-assembled onto the surface of the sensor. A simple dip-and-dry method enabled the whole detection procedure to be accomplished within 20 min. High selectivity of the sensor towards copper ions is demonstrated by both individual and coexisting assays with interference ions. This gold nanoparticle mediated amplification allowed a detection limit down to 3.1 μM. Together with good repeatability and regeneration, the QCM sensor was also applied to the analysis of copper contamination in drinking water. This work provides a flexible method for fabricating QCM sensors for the analysis of important small molecules in environmental and biological samples.

Enhanced and selective ammonia sensing of reduced graphene oxide based chemo resistive sensor at room temperature

NASA Astrophysics Data System (ADS)

Kumar, Ramesh; Kaur, Amarjeet

2016-05-01

The reduced graphene oxide thin films were fabricated by using the spin coating method. The reduced graphene oxide samples were characterised by Raman studies to obtain corresponding D and G bands at 1360 and 1590 cm-1 respectively. Fourier transform infra-red (FTIR) spectra consists of peak corresponds to sp2 hybridisation of carbon atoms at 1560 cm-1. The reduced graphene oxide based chemoresistive sensor exhibited a p-type semiconductor behaviour in ambient conditions and showed good sensitivity to different concentration of ammonia from 25 ppm to 500 ppm and excellent selectivity at room temperature. The sensor displays selectivity to several hazardous vapours such as methanol, ethanol, acetone and hydrazine hydrate. The sensor demonstrated a sensitivity of 9.8 at 25 ppm concentration of ammonia with response time of 163 seconds.

A 3D Chemically Modified Graphene Hydrogel for Fast, Highly Sensitive, and Selective Gas Sensor.

PubMed

Wu, Jin; Tao, Kai; Guo, Yuanyuan; Li, Zhong; Wang, Xiaotian; Luo, Zhongzhen; Feng, Shuanglong; Du, Chunlei; Chen, Di; Miao, Jianmin; Norford, Leslie K

2017-03-01

Reduced graphene oxide (RGO) has proved to be a promising candidate in high-performance gas sensing in ambient conditions. However, trace detection of different kinds of gases with simultaneously high sensitivity and selectivity is challenging. Here, a chemiresistor-type sensor based on 3D sulfonated RGO hydrogel (S-RGOH) is reported, which can detect a variety of important gases with high sensitivity, boosted selectivity, fast response, and good reversibility. The NaHSO 3 functionalized RGOH displays remarkable 118.6 and 58.9 times higher responses to NO 2 and NH 3 , respectively, compared with its unmodified RGOH counterpart. In addition, the S-RGOH sensor is highly responsive to volatile organic compounds. More importantly, the characteristic patterns on the linearly fitted response-temperature curves are employed to distinguish various gases for the first time. The temperature of the sensor is elevated rapidly by an imbedded microheater with little power consumption. The 3D S-RGOH is characterized and the sensing mechanisms are proposed. This work gains new insights into boosting the sensitivity of detecting various gases by combining chemical modification and 3D structural engineering of RGO, and improving the selectivity of gas sensing by employing temperature dependent response characteristics of RGO for different gases.

Direct Detection of Nucleic Acid with Minimizing Background and Improving Sensitivity Based on a Conformation-Discriminating Indicator.

PubMed

Zhu, Lixuan; Qing, Zhihe; Hou, Lina; Yang, Sheng; Zou, Zhen; Cao, Zhong; Yang, Ronghua

2017-08-25

As is well-known, the nucleic acid indicator-based strategy is one of the major approaches to monitor the nucleic acid hybridization-mediated recognition events in biochemical analysis, displaying obvious advantages including simplicity, low cost, convenience, and generality. However, conventional indicators either hold strong self-fluorescence or can be lighted by both ssDNA and dsDNA, lacking absolute selectivity for a certain conformation, always with high background interference and low sensitivity in sensing; and additional processing (e.g., nanomaterial-mediated background suppression, and enzyme-catalyzed signal amplification) is generally required to improve the detection performance. In this work, a carbazole derivative, EBCB, has been synthesized and screened as a dsDNA-specific fluorescent indicator. Compared with conventional indicators under the same conditions, EBCB displayed a much higher selective coefficient for dsDNA, with little self-fluorescence and negligible effect from ssDNA. Based on its superior capability in DNA conformation-discrimination, high sensitivity with minimizing background interference was demonstrated for direct detection of nucleic acid, and monitoring nucleic acid-based circuitry with good reversibity, resulting in low detection limit and high capability for discriminating base-mismatching. Thus, we expect that this highly specific DNA conformation-discriminating indicator will hold good potential for application in biochemical sensing and molecular logic switching.

Safer energetic materials by a nanotechnological approach.

PubMed

Siegert, Benny; Comet, Marc; Spitzer, Denis

2011-09-01

Energetic materials - explosives, thermites, populsive powders - are used in a variety of military and civilian applications. Their mechanical and electrostatic sensitivity is high in many cases, which can lead to accidents during handling and transport. These considerations limit the practical use of some energetic materials despite their good performance. For industrial applications, safety is one of the main criteria for selecting energetic materials. The sensitivity has been regarded as an intrinsic property of a substance for a long time. However, in recent years, several approaches to lower the sensitivity of a given substance, using nanotechnology and materials engineering, have been described. This feature article gives an overview over ways to prepare energetic (nano-)materials with a lower sensitivity.

A sandwich-type optical immunosensor based on the alkaline phosphatase enzyme for Salmonella thypimurium detection

NASA Astrophysics Data System (ADS)

Widyastuti, E.; Puspitasari Schonherr, M. F.; Masruroh, A.; Anggraeni, R. A.; Nisak, Y. K.; Mursidah, S.

2018-03-01

Salmonella is pathogenic bacteria that caused foodborne diseases which being called Salmonellosis. Prevalence of Salmonellosis that being caused by Salmonella thypimurium in Indonesia is quite high. However, detection of Salmonella bacteria in food still limited, complicated, and required a lot time. Sensitive optical assay for Salmonella thypimurium paper based detection has been developed by integrating sandwich assay between antibody-antigen complex and alkaline phosphatase enzyme that produce visible bluish-purple colour with presence of NBT-BCIP substrate. The results showed that Limit of Quantitation of detection is 105 CFU mL-1 with detection time 15 minutes. Linearity test between Colour intensity that produced from Salmonella concentration presence on samples showed that detection has good linearity. Selectivity test exhibited excellent sensitivity with good discrimination against Escherichia coli.

Sensitive fluorescence on-off probes for the fast detection of a chemical warfare agent mimic.

PubMed

Khan, Muhammad Shar Jhahan; Wang, Ya-Wen; Senge, Mathias O; Peng, Yu

2018-01-15

Two highly sensitive probes bearing a nucleophilic imine moiety have been utilized for the selective detection of chemical warfare agent (CWA) mimics. Diethyl chlorophosphate (DCP) was used as mimic CWAs. Both iminocoumarin-benzothiazole-based probes not only demonstrated a remarkable fluorescence ON-OFF response and good recognition, but also exhibited fast response times (10s) along with color changes upon addition of DCP. Limits of detection for the two sensors 1 and 2 were calculated as 0.065μM and 0.21μM, respectively, which are much lower than most other reported probes. These two probes not only show high sensitivity and selectivity in solution, but can also be applied for the recognition of DCP in the gas state, with significant color changes easily observed by the naked eye. Copyright © 2017 Elsevier B.V. All rights reserved.

Easy one pot synthesis of NiO/Nitrogen doped carbon spheres for highly sensitive enzyme free amperometric glucose sensors

NASA Astrophysics Data System (ADS)

Zhu, Jiajie; Yin, Haoyong; Gong, Jianying; Al-Furjan, M. S. H.; Nie, Qiulin

2018-06-01

The NiO/Nitrogen doped carbon sphere (NiO/NCS) composites were successfully achieved via an easy one pot synthetic method with urea acting as both nitrogen source and Ni precipitator. The electrocatalytic performances of the obtained NiO/NCS modified glass carbon electrodes showed superior activity for direct electrocatalytic oxidation of glucose than that of nitrogen free NiO/carbon sphere (NiO/CS), which might be due to the synergistic effect of the properties of NCS and NiO nanoparticles. The introduce of nitrogen can improve the conductivity of the NiO/NCS and accordingly accelerate the electron transport within the composites, which was very beneficial to improve the sensitivity to glucose detection for NiO/NCS modified electrodes. The NiO/NCS electrodes exhibited two corresponding linear regions of 1-800 μM and 4-9 mM with the sensitivity of 398.57 μA mM-1 cm-2 and 17.81 μA mM-1 cm-2, and the detection limit of 0.25 μM and 0.05 mM respectively. Moreover, the NiO/NCS composites have also exhibited good selectivity by adding certain amount of urea, NaCl, L-proline, L-valine, L-Leucine and ascorbic acid into the 0.1 M NaOH solution, respectively. The high sensitivity, wide glucose detection range and good selectivity of the electrodes may ensure its potential applications in the clinical diagnosis of diabetes.

Highly Sensitive and Selective Colorimetric and Off-On Fluorescent Reversible Chemosensors for Al3+ Based on the Rhodamine Fluorophore

PubMed Central

Mergu, Naveen; Singh, Ashok Kumar; Gupta, Vinod Kumar

2015-01-01

A series of rhodamine derivatives L1–L3 have been prepared and characterized by IR, 1H-NMR, 13C-NMR and ESI-MS. These compounds exhibited selective and sensitive “turn-on” fluorescent and colorimetric responses to Al3+ in methanol. Upon the addition of Al(III), the spiro ring was opened and a metal-probe complex was formed in a 1:1 stoichiometry, as was further confirmed by ESI-MS spectroscopy. The chemo-dosimeters L1–L3 exhibited good binding constants and low detection limits towards Al(III). We also successfully demonstrate the reversibility of the metal to ligand complexation (opened ring to spirolactam ring). PMID:25897498

Enhanced and selective ammonia sensing of reduced graphene oxide based chemo resistive sensor at room temperature

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

Kumar, Ramesh, E-mail: rameshphysicsdu@gmail.com; Kaur, Amarjeet, E-mail: amarkaur@physics.du.ac.in

The reduced graphene oxide thin films were fabricated by using the spin coating method. The reduced graphene oxide samples were characterised by Raman studies to obtain corresponding D and G bands at 1360 and 1590 cm{sup −1} respectively. Fourier transform infra-red (FTIR) spectra consists of peak corresponds to sp{sup 2} hybridisation of carbon atoms at 1560 cm{sup −1}. The reduced graphene oxide based chemoresistive sensor exhibited a p-type semiconductor behaviour in ambient conditions and showed good sensitivity to different concentration of ammonia from 25 ppm to 500 ppm and excellent selectivity at room temperature. The sensor displays selectivity to several hazardous vapours such asmore » methanol, ethanol, acetone and hydrazine hydrate. The sensor demonstrated a sensitivity of 9.8 at 25 ppm concentration of ammonia with response time of 163 seconds.« less

Aptamer Selection Express: A Novel Method for Rapid Single-Step Selection and Sensing of Aptamers

PubMed Central

Fan, Maomian; McBurnett, Shelly Roper; Andrews, Carrie J.; Allman, Amity M.; Bruno, John G.; Kiel, Johnathan L.

2008-01-01

Here we describe a new DNA capture element (DCE) sensing system, based on the quenching and dequenching of a double-stranded aptamer. This system shows very good sensitivity and thermal stability. While quenching, dequenching, and separating the DCE systems made from different aptamers (all selected by SELEX), an alternative method to rapidly select aptamers was developed—the Aptamer Selection Express (ASExp). This process has been used to select aptamers against different types of targets (Bacillus anthracis spores, Bacillus thuringiensis spores, MS-2 bacteriophage, ovalbumin, and botulinum neurotoxin). The DCE systems made from botulinum neurotoxin aptamers selected by ASExp have been investigated. The results of this investigation indicate that ASExp can be used to rapidly select aptamers for the DCE sensing system. PMID:19183794

Asymmetrical local adaptation of maize landraces along an altitudinal gradient.

PubMed

Mercer, Kristin; Martínez-Vásquez, Ángel; Perales, Hugo R

2008-08-01

Crop landraces are managed populations that evolve in response to gene flow and selection. Cross-pollination among fields, seed sharing by farmers, and selection by management and environmental conditions play roles in shaping crop characteristics. We used common gardens to explore the local adaptation of maize (Zea mays ssp. mays) landrace populations from Chiapas, Mexico to altitude. We sowed seeds of 21 populations from three altitudinal ranges in two common gardens and measured two characteristics that estimate fitness: likelihood of producing good quality seed and the total mass of good quality seed per plant. The probability of lowland plants producing good quality seed was invariably high regardless of garden, while highland landraces were especially sensitive to altitude. Their likelihood of producing good seed quadrupled in the highland site. The mass of good quality seed showed a different pattern, with lowland landraces producing 25% less seed mass than the other types at high elevations. Combining these two measures of fitness revealed that the highland landraces were clearly adapted to highland sites, while lowland and midland landraces appear more adapted to the midland site. We discuss this asymmetry in local adaptation in light of climate change and in situ conservation of crop genetic resources.

One-step Synthesis of Highly Luminescent Nitrogen-doped Carbon Dots for Selective and Sensitive Detection of Mercury(II) Ions and Cellular Imaging.

PubMed

Liu, Ying; Liao, Mei; He, Xueling; Liu, Xia; Kou, Xingming; Xiao, Dan

2015-01-01

In this paper, nitrogen-doped carbon dots (N-CDs) with high quantum yield (QY) of 40.5% were prepared through a facile and straightforward hydrothermal route. The as-prepared N-CDs exhibited excellent photoluminescence properties, good water-solublity and photostability, negligible cytotoxicity and favourable biocompatibility. Such N-CDs were found to serve as an effective fluorescent sensor for selective and sensitive detection of Hg(2+) in a wide linear response concentration range of 0 - 8 μM with a limit of detection (LOD) of 0.087 μM and could be applied to the determination of Hg(2+) in environmental water samples. The corresponding mechanisms were discussed in detail. Moreover, another attractive finding was that the N-CDs showed satisfactory performance in bioimaging before and after the addition of Hg(2+) in human lung cancer PC14 cells. With excellent sensitivity, selectivity and biocompatibility, such cheap carbonmaterials are potentially suitable for monitoring of Hg(2+) in environmental applications and promising for biological applications.

A highly sensitive and selective aptamer-based colorimetric sensor for the rapid detection of PCB 77.

PubMed

Cheng, Ruojie; Liu, Siyao; Shi, Huijie; Zhao, Guohua

2018-01-05

A highly sensitive, specific and simple colorimetric sensor based on aptamer was established for the detection of polychlorinated biphenyls (PCB 77). The use of unmodified gold nanoparticles as a colorimetric probe for aptamer sensors enabled the highly sensitive and selective detection of polychlorinated biphenyls (PCB 77). A linear range of 0.5nM to 900nM was obtained for the colorimetric assay with a minimum detection limit of 0.05nM. In addition, by the methods of circular dichroism, UV and naked eyes, we found that the 35 base fragments retained after cutting 5 bases from the 5 'end of aptamer plays the most significant role in the PCB 77 specific recognition process. We found a novel way to truncated nucleotides to optimize the detection of PCB 77, and the selected nucleotides also could achieve high affinity with PCB 77. At the same time, the efficient detection of the PCB 77 by our colorimetric sensor in the complex environmental water samples was realized, which shows a good application prospect. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbon nanotubes-based chemiresistive immunosensor for small molecules: detection of nitroaromatic explosives.

PubMed

Park, Miso; Cella, Lakshmi N; Chen, Wilfred; Myung, Nosang V; Mulchandani, Ashok

2010-12-15

In recent years, there has been a growing focus on use of one-dimensional (1-D) nanostructures, such as carbon nanotubes and nanowires, as transducer elements for label-free chemiresistive/field-effect transistor biosensors as they provide label-free and high sensitivity detection. While research to-date has elucidated the power of carbon nanotubes- and other 1-D nanostructure-based field effect transistors immunosensors for large charged macromolecules such as proteins and viruses, their application to small uncharged or charged molecules has not been demonstrated. In this paper we report a single-walled carbon nanotubes (SWNTs)-based chemiresistive immunosensor for label-free, rapid, sensitive and selective detection of 2,4,6-trinitrotoluene (TNT), a small molecule. The newly developed immunosensor employed a displacement mode/format in which SWNTs network forming conduction channel of the sensor was first modified with trinitrophenyl (TNP), an analog of TNT, and then ligated with the anti-TNP single chain antibody. Upon exposure to TNT or its derivatives the bound antibodies were displaced producing a large change, several folds higher than the noise, in the resistance/conductance of SWNTs giving excellent limit of detection, sensitivity and selectivity. The sensor detected between 0.5 ppb and 5000 ppb TNT with good selectivity to other nitroaromatic explosives and demonstrated good accuracy for monitoring TNT in untreated environmental water matrix. We believe this new displacement format can be easily generalized to other one-dimensional nanostructure-based chemiresistive immuno/affinity-sensors for detecting small and/or uncharged molecules of interest in environmental monitoring and health care. Copyright © 2010 Elsevier B.V. All rights reserved.

Self-templated fabrication of FeMnO3 nanoparticle-filled polypyrrole nanotubes for peroxidase mimicking with a synergistic effect and their sensitive colorimetric detection of glutathione.

PubMed

Chi, Maoqiang; Chen, Sihui; Zhong, Mengxiao; Wang, Ce; Lu, Xiaofeng

2018-06-05

A self-templated approach has been developed for the preparation of FeMnO3 nanoparticles filled in the hollow core of polypyrrole (PPy) nanotubes by an in situ polymerization process accompanied by the etching of FeMnO3 nanofibers. The prepared FeMnO3@PPy nanotubes exhibited a superior peroxidase-like activity. The catalytic reaction system has been used for the sensitive colorimetric detection of glutathione with a low detection limit and good selectivity.

Electrocatalytic oxidation of dopamine based on non-covalent functionalization of manganese tetraphenylporphyrin/reduced graphene oxide nanocomposite.

PubMed

Sakthinathan, Subramanian; Lee, Hsin Fang; Chen, Shen-Ming; Tamizhdurai, P

2016-04-15

In the present work, a reduced graphene oxide (RGO) supported manganese tetraphenylporphyrin (Mn-TPP) nanocomposite was electrochemically synthesized and used for the highly selective and sensitive detection of dopamine (DA). The nuclear magnetic resonance, scanning electron microscopy and elemental analysis were confirmed the successful formation of RGO/Mn-TPP nanocomposite. The prepared RGO/Mn-TPP nanocomposite modified electrode exhibited an enhanced electrochemical response to DA with less oxidation potential and enhanced response current. The electrochemical studies revealed that the oxidation of the DA at the composite electrode is a surface controlled process. The cyclic voltammetry, differential pulse voltammetry and amperometry methods were enable to detect DA. The working linear range of the electrode was observed from 0.3 to 188.8 μM, limit of detection was 8 nM and the sensitivity was 2.606 μA μM(-1) cm(-2). Here, the positively charged DA and negatively charged porphyrin modified RGO can accelerate the electrocatalysis of DA via electrostatic attraction, while the negatively charged ascorbic acid (AA) repulsed by the negatively charged electrode surface which supported for good selectivity. The good recovery results obtained for the determination of DA present in DA injection samples and human pathological sample further revealed the good practicality of RGO/Mn-TPP nanocomposite film modified electrode. Copyright © 2016 Elsevier Inc. All rights reserved.

Distributed photothermal spectroscopy in microstructured optical fibers: towards high-resolution mapping of gas presence over long distances.

PubMed

Garcia-Ruiz, Andres; Pastor-Graells, Juan; Martins, Hugo F; Tow, Kenny Hey; Thévenaz, Luc; Martin-Lopez, Sonia; Gonzalez-Herraez, Miguel

2017-02-06

Chemical sensing using optical fibers is often challenging, as it is generally difficult to achieve strong interaction between the guided light and the analyte at the wavelength of interest for performing the detection. Despite this difficulty, many schemes exist (and can be found in the literature) for point chemical fiber sensors. However, the challenge increases even further when it comes to performing fully distributed chemical sensing. In this case, the optical signal which interacts with the analyte is typically also the signal that has to travel to and from the interrogator: for a good sensitivity, the light should interact strongly with the analyte, leading inevitably to an increased loss and a reduced range. Few works in the literature actually provide demonstrations of truly distributed chemical sensing and, although there have been several attempts to realize these sensors (e.g. based on special fiber coatings), the vast majority of these attempts has failed to reach widespread use due to several reasons, among them: lack of sensitivity or selectivity, lack of range or resolution, cross sensitivity to temperature or strain, or need to work at specific wavelengths where fiber instrumentation becomes extremely expensive or unavailable. In this work we provide a preliminary demonstration of the possibility of achieving distributed detection of gas presence with spectroscopic selectivity, high spatial resolution, potential for long range measurements and feasibility of having most of the interrogator system working at conventional telecom wavelengths. For a full exploitation of this concept, new fibers (or more likely, fiber bundles) should be developed capable of guiding specific wavelengths in the IR (corresponding to gas absorption wavelengths) with good overlap with the analyte while also having a solid core with good transmission behavior at 1.55 μm, and good thermal coupling between the two guiding structures.

A novel fluorescent aptasensor for the highly sensitive and selective detection of cardiac troponin I based on a graphene oxide platform.

PubMed

Liu, Dongkui; Lu, Xing; Yang, Yiwen; Zhai, Yunyun; Zhang, Jian; Li, Lei

2018-05-04

Acute myocardial infarction (AMI) is one of the leading risks to global health. Thus, the rapid, accurate early diagnosis of AMI is highly critical. Human cardiac troponin I (cTnI) has been regarded as a golden biomarker for AMI due to its excellent selectivity. In this work, a novel fluorescent aptasensor based on a graphene oxide (GO) platform was developed for the highly sensitive and selective detection of cTnI. GO binds to the fluorescent anti-cTnI aptamer and quenches its fluorescence. In the presence of cTnI, the fluorescent anti-cTnI aptamer leaves the surface of GO, combines with cTnI because of the powerful affinity of the fluorescent anti-cTnI aptamer and cTnI, and then restores the fluorescence of the fluorescent anti-cTnI aptamer. Fluorescence-enhanced detection is highly sensitive and selective to cTnI. The method exhibited good analytical performance with a reasonable dynamic linearity at the concentration range of 0.10-6.0 ng/mL and a low detection limit of 0.07 ng/mL (S/N = 3). The fluorescent aptasensor also exhibited high selectivity toward cTnI compared with other interference proteins. The proposed method may be a potentially useful tool for cTnI determination in human serum. Graphical abstract A novel fluorescent aptasensor for the highly sensitive and selective detection of cardiac troponin I based on a graphene oxide platform.

Development of the "Highly Sensitive Dog" questionnaire to evaluate the personality dimension "Sensory Processing Sensitivity" in dogs.

PubMed

Braem, Maya; Asher, Lucy; Furrer, Sibylle; Lechner, Isabel; Würbel, Hanno; Melotti, Luca

2017-01-01

In humans, the personality dimension 'sensory processing sensitivity (SPS)', also referred to as "high sensitivity", involves deeper processing of sensory information, which can be associated with physiological and behavioral overarousal. However, it has not been studied up to now whether this dimension also exists in other species. SPS can influence how people perceive the environment and how this affects them, thus a similar dimension in animals would be highly relevant with respect to animal welfare. We therefore explored whether SPS translates to dogs, one of the primary model species in personality research. A 32-item questionnaire to assess the "highly sensitive dog score" (HSD-s) was developed based on the "highly sensitive person" (HSP) questionnaire. A large-scale, international online survey was conducted, including the HSD questionnaire, as well as questions on fearfulness, neuroticism, "demographic" (e.g. dog sex, age, weight; age at adoption, etc.) and "human" factors (e.g. owner age, sex, profession, communication style, etc.), and the HSP questionnaire. Data were analyzed using linear mixed effect models with forward stepwise selection to test prediction of HSD-s by the above-mentioned factors, with country of residence and dog breed treated as random effects. A total of 3647 questionnaires were fully completed. HSD-, fearfulness, neuroticism and HSP-scores showed good internal consistencies, and HSD-s only moderately correlated with fearfulness and neuroticism scores, paralleling previous findings in humans. Intra- (N = 447) and inter-rater (N = 120) reliabilities were good. Demographic and human factors, including HSP score, explained only a small amount of the variance of HSD-s. A PCA analysis identified three subtraits of SPS, comparable to human findings. Overall, the measured personality dimension in dogs showed good internal consistency, partial independence from fearfulness and neuroticism, and good intra- and inter-rater reliability, indicating good construct validity of the HSD questionnaire. Human and demographic factors only marginally affected the HSD-s suggesting that, as hypothesized for human SPS, a genetic basis may underlie this dimension within the dog species.

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

Liu, Hongying, E-mail: liuhongying@hdu.edu.cn; Gu, Chunchuan; Li, Dujuan

Graphical abstract: A non-enzymatic H{sub 2}O{sub 2} sensor with high selectivity and sensitivity based on rose-shaped FeMoO{sub 4} synthesized by the convenient microwave-assisted hydrothermal method, was fabricated. - Highlights: • Rose-shaped FeMoO{sub 4} is synthesized within 10 min via microwave-assisted hydrothermal approach. • Non-enzymatic hydrogen peroxide biosensor based on FeMoO{sub 4} nanomaterials is fabricated. • The biosensor exhibits good performance. - Abstract: In this work, we demonstrated a simple, rapid and reliable microwave-assisted hydrothermal approach to synthesize the uniform rose-shaped FeMoO{sub 4} within 10 min. The morphologies of the synthesized materials were characterized by X-ray powder diffraction and scanning electronmore » microscopy. Moreover, a non-enzymatic amperometric sensor for the detection of hydrogen peroxide (H{sub 2}O{sub 2}) was fabricated on the basis of the FeMoO{sub 4} as electrocatalysis. The resulting FeMoO{sub 4} exhibited high sensitivity and good stability for the detection of H{sub 2}O{sub 2}, which may be attributed to the rose-shaped structure of the material and the catalytic property of FeMoO{sub 4}. Amperometric response showed that the modified electrode had a good response for H{sub 2}O{sub 2} with a linear range from 1 μM to 1.6 mM, a detection limit of 0.5 μM (S/N = 3), high selectivity and short response time. Additionally, good recoveries of analytes in real milk samples confirm the reliability of the prepared sensor in practical applications.« less

Highly sensitive colorimetric and fluorescent sensor for cyanazine based on the inner filter effect of gold nanoparticles

NASA Astrophysics Data System (ADS)

Dong, Liang; Hou, Changjun; Yang, Mei; Fa, Huanbao; Wu, Huixiang; Shen, Caihong; Huo, Danqun

2016-06-01

Cyanazine residue poses a great threat to human health and its derivatives would remain in soils, natural waters, and other environmental domains for a long time. Herein, a simple, rapid, and ultra-sensitive analytical method for the determination of cyanazine (CZ) based on inner filter effect (IFE) of Au nanoparticles (AuNPs) on the fluorescence of CdTe quantum dots (QDs) is first described in this study. With the presence of citrate-stabilized AuNPs, the fluorescence of GSH-capped CdTe QDs was remarkably quenched by AuNPs via IFE. The fluorescence of the AuNP-CdTe QD system was recovered upon addition of CZ. CZ can adsorb on to the surface of AuNPs due to its cyano group that has good affinity with gold, which could induce the aggregation of AuNPs accompanying color change from red to blue. Thus, the IFE of AuNPs on CdTe QDs was weakened, and the fluorescence intensity of CdTe QDs was recovered accordingly. A good linear correlation for detection of CZ was exhibited from 0.05 to 9 μM, and the detection limit reached 0.1568 μM, which was much lower than the safety limit required by the USA, the UK, and China. In order to probe into the selectivity of AuNPs towards CZ over other pesticides, various frequently used pesticides were mixed with AuNPs. AuNP composite solution shows good selectivity towards CZ among other pesticides. This method was successfully carried out for the assessment of CZ in real samples with satisfactory results, which revealed many advantages such as high sensitivity, low cost, and non-time-consuming compared with traditional methods.

Ethanol chemiresistor with enhanced discriminative ability from acetone based on Sr-doped SnO2 nanofibers.

PubMed

Jiang, Ziqiao; Jiang, Tingting; Wang, Jinfeng; Wang, Zhaojie; Xu, Xiuru; Wang, Zongxin; Zhao, Rui; Li, Zhenyu; Wang, Ce

2015-01-01

We demonstrated a new metal oxides based chemiresistor (MOC), which exhibits fast response/recovery behavior, large sensitivity, and good selectivity to ethanol, enabled by Sr-doped SnO2 nanofibers via simple electrospinning and followed by calcination. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS) were carefully used to characterize their morphology, structure, and composition. The ethanol sensing performances based on Sr-doped SnO2 nanofibers were investigated. Comparing with the pristine SnO2 nanofibers, enhanced ethanol sensing performances (more rapid response/recovery behavior and larger response values) have been achieved owing to the basic SnO2 surface caused by Sr-doping, whereas the acetone sensing performances have been weakened. Thus, good discriminative ability to ethanol from acetone has been realized. Additionally, Sr-doped SnO2 nanofibers also exhibit good selectivity. Copyright © 2014 Elsevier Inc. All rights reserved.

ZnO Nanorods Based Enzymatic Biosensor for Selective Determination of Penicillin

PubMed Central

Ibupoto, Zafar Hussain; Ali, Syed Muhammad Usman; Khun, Kimleang; Chey, Chan Oeurn; Nur, Omer; Willander, Magnus

2011-01-01

In this study, we have successfully demonstrated the fabrication of a biosensor based on well aligned single-crystal zinc oxide (ZnO) nanorods which were grown on gold coated glass substrate using a low temperature aqueous chemical growth (ACG) method. The ZnO nanorods were immobilized with penicillinase enzyme using the physical adsorption approach in combination with N-5-azido-2-nitrobenzoyloxysuccinimide (ANB-NOS) as cross linking molecules. The potentiometric response of the sensor configuration revealed good linearity over a large logarithmic concentration range from 100 µM to 100 mM. During the investigations, the proposed sensor showed a good stability with high sensitivity of ~121 mV/decade for sensing of penicillin. A quick electrochemical response of less than 5 s with a good selectivity, repeatability, reproducibility and a negligible response to common interferents such as Na1+, K1+, d-glucose, l-glucose, ascorbic acid, uric acid, urea, sucrose, lactose, glycine, penicilloic acid and cephalosporins, was observed. PMID:25585565

ZnO Nanorods Based Enzymatic Biosensor for Selective Determination of Penicillin.

PubMed

Ibupoto, Zafar Hussain; Ali, Syed Muhammad Usman; Khun, Kimleang; Chey, Chan Oeurn; Nur, Omer; Willander, Magnus

2011-10-27

In this study, we have successfully demonstrated the fabrication of a biosensor based on well aligned single-crystal zinc oxide (ZnO) nanorods which were grown on gold coated glass substrate using a low temperature aqueous chemical growth (ACG) method. The ZnO nanorods were immobilized with penicillinase enzyme using the physical adsorption approach in combination with N-5-azido-2-nitrobenzoyloxysuccinimide (ANB-NOS) as cross linking molecules. The potentiometric response of the sensor configuration revealed good linearity over a large logarithmic concentration range from 100 µM to 100 mM. During the investigations, the proposed sensor showed a good stability with high sensitivity of ~121 mV/decade for sensing of penicillin. A quick electrochemical response of less than 5 s with a good selectivity, repeatability, reproducibility and a negligible response to common interferents such as Na1+, K1+, d-glucose, l-glucose, ascorbic acid, uric acid, urea, sucrose, lactose, glycine, penicilloic acid and cephalosporins, was observed.

Conducting Polymer-Based Nanohybrid Transducers: A Potential Route to High Sensitivity and Selectivity Sensors

PubMed Central

Park, Seon Joo; Kwon, Oh Seok; Lee, Ji Eun; Jang, Jyongsik; Yoon, Hyeonseok

2014-01-01

The development of novel sensing materials provides good opportunities to realize previously unachievable sensor performance. In this review, conducting polymer-based nanohybrids are highlighted as innovative transducers for high-performance chemical and biological sensing devices. Synthetic strategies of the nanohybrids are categorized into four groups: (1) impregnation, followed by reduction; (2) concurrent redox reactions; (3) electrochemical deposition; (4) seeding approach. Nanocale hybridization of conducting polymers with inorganic components can lead to improved sorption, catalytic reaction and/or transport behavior of the material systems. The nanohybrids have thus been used to detect nerve agents, toxic gases, volatile organic compounds, glucose, dopamine, and DNA. Given further advances in nanohybrids synthesis, it is expected that sensor technology will also evolve, especially in terms of sensitivity and selectivity. PMID:24561406

Construction of a carbon ionic liquid paste electrode based on multi-walled carbon nanotubes-synthesized Schiff base composite for trace electrochemical detection of cadmium.

PubMed

Afkhami, Abbas; Khoshsafar, Hosein; Bagheri, Hasan; Madrakian, Tayyebeh

2014-02-01

A simple, highly sensitive and selective carbon nanocomposite electrode has been developed for the electrochemical trace determination of cadmium. This sensor was designed by incorporation of multi-walled carbon nanotubes (MWCNTs) and a new synthesized Schiff base into the carbon paste ionic liquid electrode (CPE(IL)) which provides remarkably improved sensitivity and selectivity for the electrochemical stripping assay of Cd(II). The detection limit of the method was found to be 0.08 μg L(-1) (S/N=3) that is lower than the maximum contaminant level of Cd(II) allowed by the Environmental Protection Agency (EPA) in standard drinking waters. The proposed electrode exhibits good applicability for monitoring Cd(II) in various real samples. © 2013.

Sensitivity-Based Guided Model Calibration

NASA Astrophysics Data System (ADS)

Semnani, M.; Asadzadeh, M.

2017-12-01

A common practice in automatic calibration of hydrologic models is applying the sensitivity analysis prior to the global optimization to reduce the number of decision variables (DVs) by identifying the most sensitive ones. This two-stage process aims to improve the optimization efficiency. However, Parameter sensitivity information can be used to enhance the ability of the optimization algorithms to find good quality solutions in a fewer number of solution evaluations. This improvement can be achieved by increasing the focus of optimization on sampling from the most sensitive parameters in each iteration. In this study, the selection process of the dynamically dimensioned search (DDS) optimization algorithm is enhanced by utilizing a sensitivity analysis method to put more emphasis on the most sensitive decision variables for perturbation. The performance of DDS with the sensitivity information is compared to the original version of DDS for different mathematical test functions and a model calibration case study. Overall, the results show that DDS with sensitivity information finds nearly the same solutions as original DDS, however, in a significantly fewer number of solution evaluations.

High-sensitive transmission type of gas sensor based on guided-mode resonance in coupled gratings

NASA Astrophysics Data System (ADS)

Wang, La; Sang, Tian; Li, Junlang; Zhou, Jianyu; Wang, Benxin; Wang, Yueke

2018-07-01

A new type of high-sensitive transmission gas sensor based on the coupled gratings (CGs) and the corresponding Fabry-Pérot-like (FP-like) model for evaluating the resonance peaks are presented. The estimated locations of the FP-like resonance obtained by this theoretical model are well agreed with those of the exact results. It is shown that a narrow FP-like channel with high transmissivity occurs in the opaque background of the CGs, and its location is shifted linearly with the variation of the refractive index (RI) of the gaseous analyte. The transmission peak of the sideband can be selected as a reference, and it remains nearly fixed as the RI of the analyte is varied. Good sensing properties of the CGs sensor can be maintained, regardless of whether the two grating membranes are laterally aligned or not. The sensitivity of the CGs sensor is immune to the variation of the RI of the substrate. By selecting the higher order FP-like mode (m = 4), sensitivity as high as 748 nm/RIU with the figure of merit of 374 can be achieved.

Partially reduced graphene oxide based FRET on fiber optic interferometer for biochemical detection

NASA Astrophysics Data System (ADS)

Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Chen, Y. F.; Li, Y. R.

2017-04-01

An all-fiber graphene oxide (GO) based 'FRET on Fiber' concept is proposed and applied in biochemical detections. This method is of both good selectivity and high sensitivity, with detection limits of 1.2 nM, 1.3 μM and 1 pM, for metal ion, dopamine and single-stranded DNA (ssDNA), respectively.

Highly sensitive and selective detection of dopamine based on hollow gold nanoparticles-graphene nanocomposite modified electrode.

PubMed

Zhu, Wencai; Chen, Ting; Ma, Xuemei; Ma, Houyi; Chen, Shenhao

2013-11-01

Highly dispersed hollow gold-graphene (HAu-G) nanocomposites were synthesized by a two-step method. The immobilization of hollow gold nanoparticles (HAu NPs) onto the surface of graphene sheets was achieved by mixing an aqueous solution of HAu NPs with a poly(N-vinylpyrrolidone)-functionalized graphene dispersion at room temperature. A glassy carbon electrode (GCE) was modified with the nanocomposites, and the as-prepared modified electrode displayed high electrocatalytic activity and extraordinary electronic transport properties. Amperometric detection of dopamine (DA) performed with the HAu-G modified electrode exhibits a good linearity between 0.08 and 600 μM with a low detection limit of 0.05 μM (S/N=3) and also possesses good reproducibility and operational stability. The interference of ascorbic acid (AA) and uric acid (UA) can be excluded when using differential pulse voltammetric technique. In addition, this type of modified electrode can also be applied to the determination of DA content in dopamine hydrochloride injection. It is obvious that the HAu-G modified electrode provides a new way to detect dopamine sensitively and selectively. Copyright © 2013 Elsevier B.V. All rights reserved.

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.

Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) processing speed scores as measures of noncredible responding: The third generation of embedded performance validity indicators.

PubMed

Erdodi, Laszlo A; Abeare, Christopher A; Lichtenstein, Jonathan D; Tyson, Bradley T; Kucharski, Brittany; Zuccato, Brandon G; Roth, Robert M

2017-02-01

Research suggests that select processing speed measures can also serve as embedded validity indicators (EVIs). The present study examined the diagnostic utility of Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) subtests as EVIs in a mixed clinical sample of 205 patients medically referred for neuropsychological assessment (53.3% female, mean age = 45.1). Classification accuracy was calculated against 3 composite measures of performance validity as criterion variables. A PSI ≤79 produced a good combination of sensitivity (.23-.56) and specificity (.92-.98). A Coding scaled score ≤5 resulted in good specificity (.94-1.00), but low and variable sensitivity (.04-.28). A Symbol Search scaled score ≤6 achieved a good balance between sensitivity (.38-.64) and specificity (.88-.93). A Coding-Symbol Search scaled score difference ≥5 produced adequate specificity (.89-.91) but consistently low sensitivity (.08-.12). A 2-tailed cutoff on the Coding/Symbol Search raw score ratio (≤1.41 or ≥3.57) produced acceptable specificity (.87-.93), but low sensitivity (.15-.24). Failing ≥2 of these EVIs produced variable specificity (.81-.93) and sensitivity (.31-.59). Failing ≥3 of these EVIs stabilized specificity (.89-.94) at a small cost to sensitivity (.23-.53). Results suggest that processing speed based EVIs have the potential to provide a cost-effective and expedient method for evaluating the validity of cognitive data. Given their generally low and variable sensitivity, however, they should not be used in isolation to determine the credibility of a given response set. They also produced unacceptably high rates of false positive errors in patients with moderate-to-severe head injury. Combining evidence from multiple EVIs has the potential to improve overall classification accuracy. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

A rapid and selective fluorescent probe with a large Stokes shift for the detection of hydrogen sulfide.

PubMed

Chen, Song; Hou, Peng; Wang, Jing; Fu, Shuang; Liu, Lei

2018-05-28

We have successfully developed a new green-emitting H 2 S fluorescence probe employing a 2,4-dinitrophenyl ether moiety as the sensing group based on 3'-formyl-4'-hydroxybiphenyl-4-carbonitrile. This probe displayed a rapid (2 min), sensitive (the detection limit was 0.18 μM) and selective with a large Stokes shift (183 nm) in response to H 2 S, which was beneficial for fluorescence sensing and cell imaging studies. Moreover, this probe can qualitatively and quantitatively detect H 2 S with a good linearity (R 2  = 0.9991). Importantly, this probe had been used for the detection of H 2 S in living MDA-MB-231 cells with good performance. Copyright © 2018 Elsevier B.V. All rights reserved.

A novel electrochemical sensor based on zirconia/ordered macroporous polyaniline for ultrasensitive detection of pesticides.

PubMed

Wang, Yonglan; Jin, Jun; Yuan, Caixia; Zhang, Fan; Ma, Linlin; Qin, Dongdong; Shan, Duoliang; Lu, Xiaoquan

2015-01-21

A simple and mild strategy was proposed to develop a novel electrochemical sensor based on zirconia/ordered macroporous polyaniline (ZrO2/OMP) and further used for the detection of methyl parathion (MP), one of the organophosphate pesticides (OPPs). Due to the strong affinity of phosphate groups with ZrO2 and the advantages of OMP such as high catalytic activity and good conductivity, the developed sensor showed a limit of detection as low as 2.28 × 10(-10) mol L(-1) (S/N = 3) by square-wave voltammograms, and good selectivity, acceptable reproducibility and stability. Most importantly, this novel sensor was successfully applied to detect MP in real samples of apple and cabbage. It is expected that this method has potential applications in electrochemical sensing platforms with simple, sensitive, selective and fast analysis.

Highly selective dopamine electrochemical sensor based on electrochemically pretreated graphite and nafion composite modified screen printed carbon electrode.

PubMed

Ku, Shuhao; Palanisamy, Selvakumar; Chen, Shen-Ming

2013-12-01

Herein, we report a highly selective dopamine electrochemical sensor based on electrochemically pretreated graphite/nafion composite modified screen printed carbon (SPC) electrode. Electrochemically activated graphite/nafion composite was prepared by using a simple electrochemical method. Scanning electron microscope (SEM) used to characterize the surface morphology of the fabricated composite electrode. The SEM result clearly indicates that the graphitic basal planes were totally disturbed and leads to the formation of graphite nanosheets. The composite modified electrode showed an enhanced electrocatalytic activity toward the oxidation of DA when compared with either electrochemical pretreated graphite or nafion SPC electrodes. The fabricated composite electrode exhibits a good electrocatalytic oxidation toward DA in the linear response range from 0.5 to 70 μM with the detection limit of 0.023 μM. The proposed sensor also exhibits very good selectivity and stability, with the appreciable sensitivity. In addition, the proposed sensor showed satisfactory recovery results toward the commercial pharmaceutical DA samples. Copyright © 2013 Elsevier Inc. All rights reserved.

A molecularly imprinted dual-emission carbon dot-quantum dot mesoporous hybrid for ratiometric determination of anti-inflammatory drug celecoxib

NASA Astrophysics Data System (ADS)

Amjadi, Mohammad; Jalili, Roghayeh

2018-02-01

We report on a ratiometric fluorescent sensor based on dual-emission molecularly imprinted mesoporous silica embedded with carbon dots and CdTe quantum dots (mMIP@CDs/QDs) for celecoxib (CLX) as target molecule. The fluorescence of the embedded CDs is insensitive to the analyte while the green emissive QDs are selectively quenched by it. This effect is much stronger for the MIP than for the non-imprinted polymer, which indicates a good recognition ability of the mesoporous MIP. The hybrid sensor also exhibited good selectivity to CLX over other substances. The ratio of the intensity at two wavelengths (F550/F440) proportionally decreased with the increasing of CLX concentration in the range of 0.08-0.90 μM. A detection limit as low as 57 nM was achieved. Experimental results testified that this sensor was highly sensitive and selective for the detection of CLX in human serum samples.

Rapid Prototyping of a High Sensitivity Graphene Based Glucose Sensor Strip.

PubMed

Tehrani, Farshad; Reiner, Lisa; Bavarian, Behzad

2015-01-01

A rapid prototyping of an inexpensive, disposable graphene and copper nanocomposite sensor strip using polymeric flexible substrate for highly sensitive and selective nonenzymatic glucose detection has been developed and tested for direct oxidization of glucose. The CuNPs were electrochemically deposited on to the graphene sheets to improve electron transfer rates and to enhance electrocatalytic activity toward glucose. The graphene based electrode with CuNPs demonstrated a high degree of sensitivity (1101.3 ± 56 μA/mM.cm2), excellent selectivity (without an interference with Ascorbic Acid, Uric Acid, Dopamine, and Acetaminophen), good stability with a linear response to glucose ranging from 0.1 mM to 0.6 mM concentration, and detection limits of 0.025 mM to 0.9 mM. Characterization of the electrodes was performed by scanning electron microscopy (FESEM and SEM). The electrochemical properties of the modified graphene electrodes were inspected by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry.

Rapid Prototyping of a High Sensitivity Graphene Based Glucose Sensor Strip

PubMed Central

Tehrani, Farshad; Reiner, Lisa; Bavarian, Behzad

2015-01-01

A rapid prototyping of an inexpensive, disposable graphene and copper nanocomposite sensor strip using polymeric flexible substrate for highly sensitive and selective nonenzymatic glucose detection has been developed and tested for direct oxidization of glucose. The CuNPs were electrochemically deposited on to the graphene sheets to improve electron transfer rates and to enhance electrocatalytic activity toward glucose. The graphene based electrode with CuNPs demonstrated a high degree of sensitivity (1101.3±56 μA/mM.cm2), excellent selectivity (without an interference with Ascorbic Acid, Uric Acid, Dopamine, and Acetaminophen), good stability with a linear response to glucose ranging from 0.1 mM to 0.6 mM concentration, and detection limits of 0.025 mM to 0.9 mM. Characterization of the electrodes was performed by scanning electron microscopy (FESEM and SEM). The electrochemical properties of the modified graphene electrodes were inspected by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry. PMID:26678700

Total organic carbon analyzer

NASA Technical Reports Server (NTRS)

Godec, Richard G.; Kosenka, Paul P.; Smith, Brian D.; Hutte, Richard S.; Webb, Johanna V.; Sauer, Richard L.

1991-01-01

The development and testing of a breadboard version of a highly sensitive total-organic-carbon (TOC) analyzer are reported. Attention is given to the system components including the CO2 sensor, oxidation reactor, acidification module, and the sample-inlet system. Research is reported for an experimental reagentless oxidation reactor, and good results are reported for linearity, sensitivity, and selectivity in the CO2 sensor. The TOC analyzer is developed with gravity-independent components and is designed for minimal additions of chemical reagents. The reagentless oxidation reactor is based on electrolysis and UV photolysis and is shown to be potentially useful. The stability of the breadboard instrument is shown to be good on a day-to-day basis, and the analyzer is capable of 5 sample analyses per day for a period of about 80 days. The instrument can provide accurate TOC and TIC measurements over a concentration range of 20 ppb to 50 ppm C.

Aptamer-Based Biosensors for Antibiotic Detection: A Review.

PubMed

Mehlhorn, Asol; Rahimi, Parvaneh; Joseph, Yvonne

2018-06-11

Antibiotic resistance and, accordingly, their pollution because of uncontrolled usage has emerged as a serious problem in recent years. Hence, there is an increased demand to develop robust, easy, and sensitive methods for rapid evaluation of antibiotics and their residues. Among different analytical methods, the aptamer-based biosensors (aptasensors) have attracted considerable attention because of good selectivity, specificity, and sensitivity. This review gives an overview about recently-developed aptasensors for antibiotic detection. The use of various aptamer assays to determine different groups of antibiotics, like β-lactams, aminoglycosides, anthracyclines, chloramphenicol, (fluoro)quinolones, lincosamide, tetracyclines, and sulfonamides are presented in this paper.

Highly selective and sensitive nanoprobes for cyanide based on gold nanoclusters with red fluorescence emission

NASA Astrophysics Data System (ADS)

Zhang, Guomei; Qiao, Yunyun; Xu, Ting; Zhang, Caihong; Zhang, Yan; Shi, Lihong; Shuang, Shaomin; Dong, Chuan

2015-07-01

We report a novel and environmentally friendly fluorescent probe for detecting the cyanide ion (CN-) using l-amino acid oxidase (LAAOx)-protected Au nanoclusters (LAAOx@AuNCs) with red emission. The fluorescence-based sensing behaviour of LAAOx@AuNCs towards anions was investigated in buffered aqueous media. Among the anions studied, CN- was found to effectively quench the fluorescence emission of AuNCs based on CN- induced Au core decomposition. Excellent sensitivity and selectivity toward the detection of CN- in aqueous solution were observed. The CN- detection limit was determined to be approximately 180 nM, which is 15 times lower than the maximum level (2700 nM) of CN- in drinking water permitted by the World Health Organization (WHO). A linear relationship between the fluorescence intensity and CN- concentration was observed in two ranges of CN- concentration, including 3.2 × 10-6 to 3.4 × 10-5 mol L-1 and 3.81 × 10-5 to 1.04 × 10-4 mol L-1. The high sensitivity and selectivity to CN- among the 17 types of anions make the AuNCs good candidates for use in fluorescent nanoprobes of CN-.

Methylamine-Sensitive Amperometric Biosensor Based on (His)6-Tagged Hansenula polymorpha Methylamine Oxidase Immobilized on the Gold Nanoparticles

PubMed Central

Stasyuk, Nataliya Ye.; Smutok, Oleh V.; Zakalskiy, Andriy E.; Zakalska, Oksana M.; Gonchar, Mykhailo V.

2014-01-01

A novel methylamine-selective amperometric bienzyme biosensor based on recombinant primary amine oxidase isolated from the recombinant yeast strain Saccharomyces cerevisiae and commercial horseradish peroxidase is described. Two amine oxidase preparations were used: free enzyme (AMO) and covalently immobilized on the surface of gold nanoparticles (AMO-nAu). Some bioanalytical parameters (sensitivity, selectivity, and storage stability) of the developed biosensors were investigated. The sensitivity for both sensors is high: 1450 ± 113 and 700 ± 30 A−1 ·M−1 ·m−2 for AMO-nAu biosensor, respectively. The biosensors exhibit the linear range from 15 μM to 150 μM (AMO-nAu) and from 15 μM to 60 μM (AMO). The developed biosensor demonstrated a good selectivity toward methylamine (MA) (signal for dimethylamine and trimethylamine is less than 5% and for ethylamine 15% compared to MA output) and reveals a satisfactory storage stability. The constructed amperometric biosensor was used for MA assay in real samples of fish products in comparison with chemical method. The values obtained with both approaches different methods demonstrated a high correlation. PMID:25136590

Development of an enzyme free glucose sensor based on copper oxide-graphene composite by using green reducing agent ascorbic acid

NASA Astrophysics Data System (ADS)

Palve, Yogesh Pandit; Jha, Neetu

2018-05-01

In this research work we have developed high sensitive and selective glucose sensor based on copper oxide-graphene composite which is prepared by green synthesis method and used for nonenzymatic glucose sensor. In present paper we report that present method highly selective, simple, efficient, accurate, ecofriendly, less toxic. The prepared composite were characterized by material characterization like SEM, XRD and also by electrochemical characterization like CV, chronoamperometry represents that copper oxide-graphene shows excellent electrocatalytic activity towards glucose, exhibiting a good sensitivity of 103.84 µA mM-1 cm-2, a fast response time 2s, a low detection limit 0.00033µM and linear range from 10 µM-3000 µM. The present sensor can successfully apply for determination of glucose concentration in human blood sample.

[Sensitivity analysis of AnnAGNPS model's hydrology and water quality parameters based on the perturbation analysis method].

PubMed

Xi, Qing; Li, Zhao-Fu; Luo, Chuan

2014-05-01

Sensitivity analysis of hydrology and water quality parameters has a great significance for integrated model's construction and application. Based on AnnAGNPS model's mechanism, terrain, hydrology and meteorology, field management, soil and other four major categories of 31 parameters were selected for the sensitivity analysis in Zhongtian river watershed which is a typical small watershed of hilly region in the Taihu Lake, and then used the perturbation method to evaluate the sensitivity of the parameters to the model's simulation results. The results showed that: in the 11 terrain parameters, LS was sensitive to all the model results, RMN, RS and RVC were generally sensitive and less sensitive to the output of sediment but insensitive to the remaining results. For hydrometeorological parameters, CN was more sensitive to runoff and sediment and relatively sensitive for the rest results. In field management, fertilizer and vegetation parameters, CCC, CRM and RR were less sensitive to sediment and particulate pollutants, the six fertilizer parameters (FR, FD, FID, FOD, FIP, FOP) were particularly sensitive for nitrogen and phosphorus nutrients. For soil parameters, K is quite sensitive to all the results except the runoff, the four parameters of the soil's nitrogen and phosphorus ratio (SONR, SINR, SOPR, SIPR) were less sensitive to the corresponding results. The simulation and verification results of runoff in Zhongtian watershed show a good accuracy with the deviation less than 10% during 2005- 2010. Research results have a direct reference value on AnnAGNPS model's parameter selection and calibration adjustment. The runoff simulation results of the study area also proved that the sensitivity analysis was practicable to the parameter's adjustment and showed the adaptability to the hydrology simulation in the Taihu Lake basin's hilly region and provide reference for the model's promotion in China.

The binding of [3H]-propylbenzilylcholine mustard by longitudinal muscle strips from guinea-pig small intestine

PubMed Central

Burgen, A.S.V.; Hiley, C.R.; Young, J.M.

1974-01-01

1 The synthesis of tritium labelled propylbenzilylcholine mustard ([3H]-PrBCM; N-2′-chloroethyl-N-[2″, 3″-3H2] propyl-2-aminoethyl benzilate) is described. 2 The uptake by muscle strips was measured and shown to be considerably increased by previous immersion of the muscle in distilled water. 3 A considerable part of the uptake is inhibited selectively by atropine, but not by nicotinic antagonists. A number of muscarinic agonists also inhibit uptake and their apparent affinity constants have been determined. 4 The uptake by atropine-sensitive sites is temperature-insensitive, whereas the other sites are temperature-sensitive. Recovery is highly temperature-sensitive and there is good agreement between recovery of sensitivity to agonists and loss of radioactivity from the muscle. PMID:4150888

A highly sensitive and selective sensor based on a graphene-coated carbon paste electrode modified with a computationally designed boron-embedded duplex molecularly imprinted hybrid membrane for the sensing of lamotrigine.

PubMed

Wang, Hongjuan; Qian, Duo; Xiao, Xilin; Gao, Shuqin; Cheng, Jianlin; He, Bo; Liao, Lifu; Deng, Jian

2017-08-15

An innovative electrochemical sensor, based on a carbon paste electrode (CPE) modified with graphene (GR) and a boron-embedded duplex molecularly imprinted hybrid membrane (B-DMIHM), was fabricated for the highly sensitive and selective determination of lamotrigine (LMT). Density functional theory (DFT) was employed to study the interactions between the template and monomers to screen appropriate functional monomers for rational design of the B-DMIHM. The distinct synergic effect of GR and B-DMIHM was evidenced by the positive shift of the reduction peak potential of LMT at B-DMIHM/GR modified CPE (B-DMIHM/GR/CPE) by about 300mV, and the 13-fold amplification of the peak current, compared to a bare carbon paste electrode (CPE). The electrochemical reduction mechanism of lamotrigine was investigated by different voltammetric techniques. It was illustrated that square wave voltammetry (SWV) was more sensitive than different pulse voltammetry (DPV) for the quantitative analysis of LMT. Thereafter, a highly sensitive electroanalytical method for LMT was established by SWV at B-DMIHM/GR/CPE with a good linear relationship from 5.0×10 -8 to 5.0×10 -5 and 5.0×10 -5 to 3.0×10 -4 molL -1 with a lower detection limit (1.52×10 -9 molL -1 ) based on the lower linear range(S/N=3). The practical application of the sensor was demonstrated by determining the concentration of LMT in pharmaceutical and biological samples with good precision (RSD 1.04-4.41%) and acceptable recoveries (92.40-107.0%). Copyright © 2017 Elsevier B.V. All rights reserved.

Optical Properties of the DIRC Fused Silica Radiator

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

Convery, Mark R

2003-04-15

The DIRC detector is successfully operating as the hadronic particle identification system for the BaBar experiment at SLAC. The production of its Cherenkov radiator required much effort in practice, both in manufacture and conception, which in turn required a large number of R&D measurements. One of the major outcomes of this R&D work was an understanding of methods to select radiation hard and optically uniform fused silica material. Others included measurement of the wavelength dependency of the internal reflection coefficient, and its sensitivity to the surface pollution, selection of the radiator support, selection of good optical glue, etc. This notemore » summarizes the optical R&D test results.« less

Highly sensitive chemiluminescence immunoassay on chitosan membrane modified paper platform using TiO2 nanoparticles/multiwalled carbon nanotubes as label.

PubMed

Li, Weiping; Ge, Shenguang; Wang, Shoumei; Yan, Mei; Ge, Lei; Yu, Jinghua

2013-01-01

A highly sensitive chemiluminescence (CL) immunoassay was incorporated into a low-cost microfluidic paper-based analytical device (μ-PAD) to fabricate a facile paper-based CL immunodevice (denoted as μ-PCLI). This μ-PCLI was constructed by covalently immobilizing capture antibody on a chitosan membrane modified μ-PADs, which was developed by simple wax printing methodology. TiO2 nanoparticles coated multiwalled carbon nanotubes (TiO2/MWCNTs) were synthesized as an amplification catalyst tag to label signal antibody (Ab2). After sandwich-type immunoreactions, the TiO2/MWCNTs were captured on the surface of μ-PADs to catalyze the luminol-p-iodophenol-H2O2 CL system, which produced an enhanced CL emission. Using prostate-specific antigen as a model analyte, the approach provided a good linear response range from 0.001 to 20 ng/mL with a low detection limit of 0.8 pg/mL under optimal conditions. This μ-PCLI showed good reproducibility, selectivity and stability. The assay results of prostate-specific antigen in clinical serum samples were in good agreement with that obtained by commercially used electrochemiluminescence methods at the Cancer Research Center of Shandong Tumor Hospital (Jinan, Shandong Province, China). This μ-PCLI could be very useful to realize highly sensitive, qualitative point-of-care testing in developing or developed countries. Copyright © 2013 John Wiley & Sons, Ltd.

Environmentally friendly synthesis of CeO2 nanoparticles for the catalytic oxidation of benzyl alcohol to benzaldehyde and selective detection of nitrite

NASA Astrophysics Data System (ADS)

Tamizhdurai, P.; Sakthinathan, Subramanian; Chen, Shen-Ming; Shanthi, K.; Sivasanker, S.; Sangeetha, P.

2017-04-01

Cerium oxide nanoparticles (CeO2 NPs) are favorable in nanotechnology based on some remarkable properties. In this study, the crystalline CeO2 NPs are successfully prepared by an efficient microwave combustion (MCM) and conventional route sol-gel (CRSGM) methods. The structural morphology of the as-prepared CeO2 NPs was investigated by various spectroscopic and analytical techniques. Moreover, the XRD pattern confirmed the formation of CeO2 NPs as a face centered cubic structure. The magnetometer studies indicated the low saturation magnetization (23.96 emu/g) of CeO2 NPs for weak paramagnetic and high saturation magnetization (32.13 emu/g) of CeO2 NPs for super paramagnetic. After that, the oxidation effect of benzyl alcohol was investigated which reveals good conversion and selectivity. Besides, the CeO2 NPs modified glassy carbon electrode (GCE) used for the detection of nitrite with linear concentration range (0.02-1200 μM), low limit of detection (0.21 μM) and higher sensitivity (1.7238 μAμM-1 cm-2). However, the CeO2 NPs modified electrode has the fast response, high sensitivity and good selectivity. In addition, the fabricated electrode is applied for the determination of nitrite in various water samples. Eventually, the CeO2 NPs can be regarded as an effective way to enhance the catalytic activity towards the benzyl alcohol and nitrite.

Environmentally friendly synthesis of CeO2 nanoparticles for the catalytic oxidation of benzyl alcohol to benzaldehyde and selective detection of nitrite

PubMed Central

Tamizhdurai, P.; Sakthinathan, Subramanian; Chen, Shen-Ming; Shanthi, K.; Sivasanker, S.; Sangeetha, P.

2017-01-01

Cerium oxide nanoparticles (CeO2 NPs) are favorable in nanotechnology based on some remarkable properties. In this study, the crystalline CeO2 NPs are successfully prepared by an efficient microwave combustion (MCM) and conventional route sol-gel (CRSGM) methods. The structural morphology of the as-prepared CeO2 NPs was investigated by various spectroscopic and analytical techniques. Moreover, the XRD pattern confirmed the formation of CeO2 NPs as a face centered cubic structure. The magnetometer studies indicated the low saturation magnetization (23.96 emu/g) of CeO2 NPs for weak paramagnetic and high saturation magnetization (32.13 emu/g) of CeO2 NPs for super paramagnetic. After that, the oxidation effect of benzyl alcohol was investigated which reveals good conversion and selectivity. Besides, the CeO2 NPs modified glassy carbon electrode (GCE) used for the detection of nitrite with linear concentration range (0.02–1200 μM), low limit of detection (0.21 μM) and higher sensitivity (1.7238 μAμM−1 cm−2). However, the CeO2 NPs modified electrode has the fast response, high sensitivity and good selectivity. In addition, the fabricated electrode is applied for the determination of nitrite in various water samples. Eventually, the CeO2 NPs can be regarded as an effective way to enhance the catalytic activity towards the benzyl alcohol and nitrite. PMID:28406231

Choosing between atmospheric pressure chemical ionization and electrospray ionization interfaces for the HPLC/MS analysis of pesticides

USGS Publications Warehouse

Thurman, E.M.; Ferrer, I.; Barcelo, D.

2001-01-01

An evaluation of over 75 pesticides by high-performance liquid chromatography/mass spectrometry (HPLC/MS) clearly shows that different classes of pesticides are more sensitive using either atmospheric pressure chemical ionization (APCI) or electrospray ionization (ESI). For example, neutral and basic pesticides (phenylureas, triazines) are more sensitive using APCI (especially positive ion). While cationic and anionic herbicides (bipyridylium ions, sulfonic acids) are more sensitive using ESI (especially negative ion). These data are expressed graphically in a figure called an ionization-continuum diagram, which shows that protonation in the gas phase (proton affinity) and polarity in solution, expressed as proton addition or subtraction (pKa), is useful in selecting APCI or ESI. Furthermore, sodium adduct formation commonly occurs using positive ion ESI but not using positive ion APCI, which reflects the different mechanisms of ionization and strengthens the usefulness of the ionization-continuum diagram. The data also show that the concept of "wrong-way around" ESI (the sensitivity of acidic pesticides in an acidic mobile phase) is a useful modification of simple pKa theory for mobile-phase selection. Finally, this finding is used to enhance the chromatographic separation of oxanilic and sulfonic acid herbicides while maintaining good sensitivity in LC/MS using ESI negative.

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.

Uniform manganese hexacyanoferrate hydrate nanocubes featuring superior performance for low-cost supercapacitors and nonenzymatic electrochemical sensors

NASA Astrophysics Data System (ADS)

Pang, Huan; Zhang, Yizhou; Cheng, Tao; Lai, Wen-Yong; Huang, Wei

2015-09-01

Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity.Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04322k

Analysis and Implementation of Methodologies for the Monitoring of Changes in Eye Fundus Images

NASA Astrophysics Data System (ADS)

Gelroth, A.; Rodríguez, D.; Salvatelli, A.; Drozdowicz, B.; Bizai, G.

2011-12-01

We present a support system for changes detection in fundus images of the same patient taken at different time intervals. This process is useful for monitoring pathologies lasting for long periods of time, as are usually the ophthalmologic. We propose a flow of preprocessing, processing and postprocessing applied to a set of images selected from a public database, presenting pathological advances. A test interface was developed designed to select the images to be compared in order to apply the different methods developed and to display the results. We measure the system performance in terms of sensitivity, specificity and computation times. We have obtained good results, higher than 84% for the first two parameters and processing times lower than 3 seconds for 512x512 pixel images. For the specific case of detection of changes associated with bleeding, the system responds with sensitivity and specificity over 98%.

Effect of electrode gap on the sensing properties of multiwalled carbon nanotubes based gas sensor

NASA Astrophysics Data System (ADS)

Saheed, Mohamed Shuaib Mohamed; Mohamed, Norani Muti; Burhanudin, Zainal Arif

2016-11-01

Vertically aligned multiwalled carbon nanotubes (MWCNT) were grown on Si substrate coated with alumina and iron using chemical vapor deposition. Electrode gap of 10, 25 and 50 µm were adopted to determine the effect of varying gap spacing on the sensing properties such as voltage breakdown, sensitivity and selectivity for three gases namely argon, carbon dioxide and ammonia. Argon has the lowest voltage breakdown for every electrode gap. The fabricated MWCNT based gas sensor drastically reduced the voltage breakdown by 89.5% when the electrode spacing is reduced from 50 µm to 10 µm. The reduction is attributed to the high non-uniform electric field between the electrodes caused by the protrusion of nanotips. The sensor shows good sensitivity and selectivity with the ability to detect the gas in the mixture with air provided that the concentration is ≥ 20% where the voltage breakdown will be close to the pure gas.

Vanadium doped tin dioxide as a novel sulfur dioxide sensor.

PubMed

Das, S; Chakraborty, S; Parkash, O; Kumar, D; Bandyopadhyay, S; Samudrala, S K; Sen, A; Maiti, H S

2008-04-15

Considering the short-term exposure limit of SO2 to be 5 ppm, we first time report that semiconductor sensors based on vanadium doped SnO2 can be used for SO2 leak detection because of their good sensitivity towards SO2 at concentrations down to 5 ppm. Such sensors are quite selective in presence of other gases like carbon monoxide, methane and butane. The high sensitivity of vanadium doped tin dioxide towards SO2 may be understood by considering the oxidation of sulfur dioxide to sulfur trioxide on SnO2 surface through redox cycles of vanadium-sulfur-oxygen adsorbed species.

Competition and cooperation among different punishing strategies in the spatial public goods game

NASA Astrophysics Data System (ADS)

Chen, Xiaojie; Szolnoki, Attila; Perc, Matjaž

2015-07-01

Inspired by the fact that people have diverse propensities to punish wrongdoers, we study a spatial public goods game with defectors and different types of punishing cooperators. During the game, cooperators punish defectors with class-specific probabilities and subsequently share the associated costs of sanctioning. We show that in the presence of different punishing cooperators the highest level of public cooperation is always attainable through a selection mechanism. Interestingly, the selection does not necessarily favor the evolution of punishers who would be able to prevail on their own against the defectors, nor does it always hinder the evolution of punishers who would be unable to prevail on their own. Instead, the evolutionary success of punishing strategies depends sensitively on their invasion velocities, which in turn reveals fascinating examples of both competition and cooperation among them. Furthermore, we show that under favorable conditions, when punishment is not strictly necessary for the maintenance of public cooperation, the less aggressive, mild form of sanctioning is the sole victor of the selection process. Our work reveals that natural strategy selection cannot only promote, but sometimes also hinders competition among prosocial strategies.

A single-walled carbon nanotube thin film-based pH-sensing microfluidic chip.

PubMed

Li, Cheng Ai; Han, Kwi Nam; Pham, Xuan-Hung; Seong, Gi Hun

2014-04-21

A novel microfluidic pH-sensing chip was developed based on pH-sensitive single-walled carbon nanotubes (SWCNTs). In this study, the SWCNT thin film acted both as an electrode and a pH-sensitive membrane. The potentiometric pH response was observed by electronic structure changes in the semiconducting SWCNTs in response to the pH level. In a microfluidic chip consisting of a SWCNT pH-sensing working electrode and an Ag/AgCl reference electrode, the calibration plot exhibited promising pH-sensing performance with an ideal Nernstian response of 59.71 mV pH(-1) between pH 3 and 11 (standard deviation of the sensitivity is 1.5 mV pH(-1), R(2) = 0.985). Moreover, the SWCNT electrode in the microfluidic device showed no significant variation at any pH value in the range of the flow rate between 0.1 and 15 μl min(-1). The selectivity coefficients of the SWCNT electrode revealed good selectivity against common interfering ions.

The SPAI-18, a brief version of the social phobia and anxiety inventory: reliability and validity in clinically referred and non-referred samples.

PubMed

de Vente, Wieke; Majdandžić, Mirjana; Voncken, Marisol J; Beidel, Deborah C; Bögels, Susan M

2014-03-01

We developed a new version of the Social Phobia and Anxiety Inventory (SPAI) in order to have a brief instrument for measuring social anxiety and social anxiety disorder (SAD) with a strong conceptual foundation. In the construction phase, a set of items representing 5 core aspects of social anxiety was selected by a panel of social anxiety experts. The selected item pool was validated using factor analysis, reliability analysis, and diagnostic analysis in a sample of healthy participants (N = 188) and a sample of clinically referred participants diagnosed with SAD (N = 98). This procedure resulted in an abbreviated version of the Social Phobia Subscale of the SPAI consisting of 18 items (i.e. the SPAI-18), which correlated strongly with the Social Phobia Subscale of the original SPAI (both groups r = .98). Internal consistency and diagnostic characteristics using a clinical cut-off score > 48 were good to excellent (Cronbach's alpha healthy group = .93; patient group = .91; sensitivity: .94; specificity: .88). The SPAI-18 was further validated in a community sample of parents-to-be without SAD (N = 237) and with SAD (N = 65). Internal consistency was again excellent (both groups Cronbach's alpha = .93) and a screening cut-off of > 36 proved to result in good sensitivity and specificity. The SPAI-18 also correlated strongly with other social anxiety instruments, supporting convergent validity. In sum, the SPAI-18 is a psychometrically sound instrument with good screening capacity for social anxiety disorder in clinical as well as community samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

Wavenumber selection based analysis in Raman spectroscopy improves skin cancer diagnostic specificity at high sensitivity levels (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhao, Jianhua; Zeng, Haishan; Kalia, Sunil; Lui, Harvey

2017-02-01

Background: Raman spectroscopy is a non-invasive optical technique which can measure molecular vibrational modes within tissue. A large-scale clinical study (n = 518) has demonstrated that real-time Raman spectroscopy could distinguish malignant from benign skin lesions with good diagnostic accuracy; this was validated by a follow-up independent study (n = 127). Objective: Most of the previous diagnostic algorithms have typically been based on analyzing the full band of the Raman spectra, either in the fingerprint or high wavenumber regions. Our objective in this presentation is to explore wavenumber selection based analysis in Raman spectroscopy for skin cancer diagnosis. Methods: A wavenumber selection algorithm was implemented using variably-sized wavenumber windows, which were determined by the correlation coefficient between wavenumbers. Wavenumber windows were chosen based on accumulated frequency from leave-one-out cross-validated stepwise regression or least and shrinkage selection operator (LASSO). The diagnostic algorithms were then generated from the selected wavenumber windows using multivariate statistical analyses, including principal component and general discriminant analysis (PC-GDA) and partial least squares (PLS). A total cohort of 645 confirmed lesions from 573 patients encompassing skin cancers, precancers and benign skin lesions were included. Lesion measurements were divided into training cohort (n = 518) and testing cohort (n = 127) according to the measurement time. Result: The area under the receiver operating characteristic curve (ROC) improved from 0.861-0.891 to 0.891-0.911 and the diagnostic specificity for sensitivity levels of 0.99-0.90 increased respectively from 0.17-0.65 to 0.20-0.75 by selecting specific wavenumber windows for analysis. Conclusion: Wavenumber selection based analysis in Raman spectroscopy improves skin cancer diagnostic specificity at high sensitivity levels.

Surface plasmon resonance sensor for antibiotics detection based on photo-initiated polymerization molecularly imprinted array.

PubMed

Luo, Qiaohui; Yu, Neng; Shi, Chunfei; Wang, Xiaoping; Wu, Jianmin

2016-12-01

A surface plasmon resonance (SPR) sensor combined with nanoscale molecularly imprinted polymer (MIP) film as recognition element was developed for selective detection of the antibiotic ciprofloxacin (CIP). The MIP film on SPR sensor chip was prepared by in situ photo-initiated polymerization method which has the advantages of short polymerization time, controllable thickness and good uniformity. The surface wettability and thickness of MIP film on SPR sensor chip were characterized by static contact angle measurement and stylus profiler. The MIP-SPR sensor exhibited high selectivity, sensitivity and good stability for ciprofloxacin. The imprinting factors of the MIP-SPR sensor to ciprofloxacin and its structural analogue ofloxacin were 2.63 and 3.80, which is much higher than those to azithromycin, dopamine and penicillin. The SPR response had good linear relation with CIP concentration over the range 10 -11 -10 -7 molL -1 . The MIP-SPR sensor also showed good repeatability and stability during cyclic detections. On the basis of the photo-initiated polymerization method, a surface plasmon resonance imaging (SPRi) chip modified with three types of MIP sensing spots was fabricated. The MIPs-SPRi sensor shows different response patterns to ciprofloxacin and azithromycin, revealing the ability to recognize different antibiotic molecules. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

Abolhasani, Jafar; Naderali, Roza; Hassanzadeh, Javad

2016-01-01

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

Water-Soluble Nonconjugated Polymer Nanoparticles with Strong Fluorescence Emission for Selective and Sensitive Detection of Nitro-Explosive Picric Acid in Aqueous Medium.

PubMed

Liu, Shi Gang; Luo, Dan; Li, Na; Zhang, Wei; Lei, Jing Lei; Li, Nian Bing; Luo, Hong Qun

2016-08-24

Water-soluble nonconjugated polymer nanoparticles (PNPs) with strong fluorescence emission were prepared from hyperbranched poly(ethylenimine) (PEI) and d-glucose via Schiff base reaction and self-assembly in aqueous phase. Preparation of the PEI-d-glucose (PEI-G) PNPs was facile (one-pot reaction) and environmentally friendly under mild conditions. Also, PEI-G PNPs showed a high fluorescence quantum yield in aqueous solution, and the fluorescence properties (such as concentration- and solvent-dependent fluorescence) and origin of intrinsic fluorescence were investigated and discussed. PEI-G PNPs were then used to develop a fluorescent probe for fast, selective, and sensitive detection of nitro-explosive picric acid (PA) in aqueous medium, because the fluorescence can be easily quenched by PA whereas other nitro-explosives and structurally similar compounds only caused negligible quenching. A wide linear range (0.05-70 μM) and a low detection limit (26 nM) were obtained. The fluorescence quenching mechanism was carefully explored, and it was due to a combined effect of electron transfer, resonance energy transfer, and inner filter effect between PA and PEI-G PNPs, which resulted in good selectivity and sensitivity for PA. Finally, the developed sensor was successfully applied to detection of PA in environmental water samples.

Ultra-sensitive and selective Hg{sup 2+} detection based on fluorescent carbon dots

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

Liu, Ruihua; Li, Haitao; Kong, Weiqian

2013-07-15

Graphical abstract: Fluorescent carbon dots were efficiently synthesized by one-step sodium hydroxide-assisted reflux method from PEG and demonstrated to show high selectivity toward Hg2+ ions detection. - Highlights: • FCDs were synthesized by one-step sodium hydroxide-assisted reflux method from PEG. • The FCDs emit blue photoluminescence and have upconversion fluorescent property. • The FCDs show ultra-sensitive detective ability for Hg{sup 2+} ions. - Abstract: Fluorescent carbon dots (FCDs) were efficiently synthesized by one-step sodium hydroxide-assisted reflux method from poly(ethylene glycol) (PEG). The obtained FCDs exhibit excellent water-solubility and high stability. Under the UV irradiation, the FCDs could emit bright bluemore » photoluminescence, and also they were found to show excellent up-conversion fluorescence. It was further demonstrated that such FCDs can serve as effective fluorescent sensing platform for Hg{sup 2+} ions detection with ultra-sensitivity and selectivity. The sensing system achieved a limit of detection as low as 1 fM, which is much lower than all the previous reported sensing systems for Hg{sup 2+} ions detection. This FCDs sensing system has been successfully applied for the analysis of Hg{sup 2+} ions in water samples from river, lake, and tap water, showing good practical feasibility.« less

Self-locked aptamer probe mediated cascade amplification strategy for highly sensitive and selective detection of protein and small molecule.

PubMed

Li, Wei; Jiang, Wei; Wang, Lei

2016-10-12

In this work, a novel self-locked aptamer probe mediated cascade amplification strategy has been constructed for highly sensitive and specific detection of protein. First, the self-locked aptamer probe was designed with three functions: one was specific molecular recognition attributed to the aptamer sequence, the second was signal transduction owing to the transduction sequence, and the third was self-locking through the hybridization of the transduction sequence and part of the aptamer sequence. Then, the aptamer sequence specific recognized the target and folded into a three-way helix junction, leading to the release of the transduction sequence. Next, the 3'-end of this three-way junction acted as primer to trigger the strand displacement amplification (SDA), yielding a large amount of primers. Finally, the primers initiated the dual-exponential rolling circle amplification (DE-RCA) and generated numerous G-quadruples sequences. By inserting the fluorescent dye N-methyl mesoporphyrin IX (NMM), enhanced fluorescence signal was achieved. In this strategy, the self-locked aptamer probe was more stable to reduce the interference signals generated by the uncontrollable folding in unbounded state. Through the cascade amplification of SDA and DE-RCA, the sensitivity was further improved with a detection limit of 3.8 × 10(-16) mol/L for protein detection. Furthermore, by changing the aptamer sequence of the probe, sensitive and selective detection of adenosine has been also achieved, suggesting that the proposed strategy has good versatility and can be widely used in sensitive and selective detection of biomolecules. Copyright © 2016 Elsevier B.V. All rights reserved.

An improved biosensor for acetaldehyde determination using a bienzymatic strategy at poly(neutral red) modified carbon film electrodes.

PubMed

Ghica, Mariana Emilia; Pauliukaite, Rasa; Marchand, Nicolas; Devic, Eric; Brett, Christopher M A

2007-05-15

Improved biosensors for acetaldehyde determination have been developed using a bienzymatic strategy, based on a mediator-modified carbon film electrode and co-immobilisation of NADH oxidase and aldehyde dehydrogenase. Modification of the carbon film electrode with poly(neutral red) mediator resulted in a sensitive, low-cost and reliable NADH detector. Immobilisation of the enzymes was performed using encapsulation in a sol-gel matrix or cross-linking with glutaraldehyde. The bienzymatic biosensors were characterized by studying the influence of pH, applied potential and co-factors. The sol-gel and glutaraldehyde biosensors showed a linear response up to 60 microM and 100 microM, respectively, with detection limits of 2.6 microM and 3.3 microM and sensitivities were 1.7 microA mM(-1) and 5.6 microA mM(-1). The optimised biosensors showed good stability and good selectivity and have been tested for application for the determination of acetaldehyde in natural samples such as wine.

A highly sensitive hydrogen sensor with gas selectivity using a PMMA membrane-coated Pd nanoparticle/single-layer graphene hybrid.

PubMed

Hong, Juree; Lee, Sanggeun; Seo, Jungmok; Pyo, Soonjae; Kim, Jongbaeg; Lee, Taeyoon

2015-02-18

A polymer membrane-coated palladium (Pd) nanoparticle (NP)/single-layer graphene (SLG) hybrid sensor was fabricated for highly sensitive hydrogen gas (H2) sensing with gas selectivity. Pd NPs were deposited on SLG via the galvanic displacement reaction between graphene-buffered copper (Cu) and Pd ion. During the galvanic displacement reaction, graphene was used as a buffer layer, which transports electrons from Cu for Pd to nucleate on the SLG surface. The deposited Pd NPs on the SLG surface were well-distributed with high uniformity and low defects. The Pd NP/SLG hybrid was then coated with polymer membrane layer for the selective filtration of H2. Because of the selective H2 filtration effect of the polymer membrane layer, the sensor had no responses to methane, carbon monoxide, or nitrogen dioxide gas. On the contrary, the PMMA/Pd NP/SLG hybrid sensor exhibited a good response to exposure to 2% H2: on average, 66.37% response within 1.81 min and recovery within 5.52 min. In addition, reliable and repeatable sensing behaviors were obtained when the sensor was exposed to different H2 concentrations ranging from 0.025 to 2%.

Highly selective and sensitive trimethylamine gas sensor based on cobalt imidazolate framework material.

PubMed

Chen, Er-Xia; Fu, Hong-Ru; Lin, Rui; Tan, Yan-Xi; Zhang, Jian

2014-12-24

A cobalt imidazolate (im) framework material [Co(im)2]n was employed to use as a trimethylamine (TMA) gas sensor and the [Co(im)2]n sensor can be easily fabricated by using Ag-Pd interdigitated electrodes. Gas sensing measurement indicated that the [Co(im)2]n sensor shows excellent selectivity, high gas response and a low detection limit level of 2 ppm to TMA at 75 °C. The good selectivity and high response to TMA of the sensor based on [Co(im)2]n may be attributed to the weak interaction between the TMA molecules and the [Co(im)2]n framework. That may provide an ideal candidate for detecting freshness of fish and seafood.

Polydimethylsiloxane rod extraction, a novel technique for the determination of organic micropollutants in water samples by thermal desorption-capillary gas chromatography-mass spectrometry.

PubMed

Montero, L; Popp, P; Paschke, A; Pawliszyn, J

2004-01-30

A novel, simple and inexpensive approach to absorptive extraction of organic compounds from environmental samples is presented. It consists of a polydimethylsiloxane rod used as an extraction media, enriched with analytes during shaking, then thermally desorbed and analyzed by GC-MS. Its performance was illustrated and evaluated for the enrichment of sub- to ng/l of selected chlorinated compounds (chlorobenzenes and polychlorinated biphenyls) in water samples. The new approach was compared to the stir bar sorptive extraction performance. A natural ground water sample from Bitterfeld, Germany, was also extracted using both methods, showing good agreement. The proposed approach presented good linearity, high sensitivity, good blank levels and recoveries comparable to stir bars, together with advantages such as simplicity, lower cost and higher feasibility.

A rapid, sensitive and selective electrochemical biosensor with concanavalin A for the preemptive detection of norovirus.

PubMed

Hong, Sung A; Kwon, Joseph; Kim, Duwoon; Yang, Sung

2015-02-15

Norovirus (NoV) is a foodborne pathogen that can cause sporadic and epidemic gastrointestinal diseases. Rapid screening is crucial to promptly identify the presence of NoV and prevent food poisoning. Here, we present a sensitive, selective, and rapid electrochemical biosensor for the detection of NoV. The proposed electrochemical biosensor is composed of a nanostructured gold electrode conjugated with concanavalin A (ConA). ConA functions as a recognition element that selectively captures NoV. Cyclic voltammetry revealed a linear relationship (R(2) = 0.998) between the current and concentration of NoV (in the range of 10(2) and 10(6) copies/mL), with a relatively short assay time (1h) and a good detection limit (35 copies/mL). Additionally, the signals of Hepatitis A and E in the selectively test were found to be only 2.0% and 2.8% of the NoV signal at an identical concentration of 10(3) copies/mL, proving that the electrochemical biosensor has a selectively of approximately 98%. Moreover, the concentration of NoV was measured in a realistic environment, i.e., a sample solution extracted from lettuce, to demonstrate a potential application of the proposed biosensor (LoD = 60 copies/mL). Copyright © 2014 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Zargoosh, Kiomars; Babadi, Fatemeh Farhadian

2015-02-01

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

Electrochemical detection of dopamine using porphyrin-functionalized graphene.

PubMed

Wu, Li; Feng, Lingyan; Ren, Jinsong; Qu, Xiaogang

2012-04-15

A new type of porphyrin-functionalized graphene was synthesized and used for highly selective and sensitive detection of dopamine (DA). The aromatic π-π stacking and electrostatic attraction between positively-charged dopamine and negatively-charged porphyrin-modified graphene can accelerate the electron transfer whereas weakening ascorbic acid (AA) and uric acid (UA) oxidation on the porphyrin-functionalized graphene-modified electrode. Differential pulse voltammetry was used for electrochemical detection, the separation of the oxidation peak potentials for AA-DA, DA-UA and UA-AA is about 188 mV, 144 mV and 332 mV, which allows selectively determining DA. The detection limit of DA can be as low as 0.01 μM. More importantly, the sensor we presented can detect DA in the presence of large excess of ascorbic acid and uric acid. With good sensitivity and selectivity, the present method was applied to the determination of DA in real hydrochloride injection sample, human urine and serum samples, respectively, and the results was satisfactory. Copyright © 2012 Elsevier B.V. All rights reserved.

Fluorescence detection of trace PCB101 based on PITC immobilized on porous AAO membrane.

PubMed

Wang, Meiling; Meng, Guowen; Huang, Qing; Li, Mingtao; Li, Zhongbo; Tang, Chaolong

2011-01-21

A sensitive and selective fluorescent membrane for rapid detection of trace 2,2',4,5,5'-pentachlorinated biphenyl (PCB101) has been achieved by immobilizing the fluorophore phenyl isothiocyanate (PITC) onto porous anodic aluminium oxide (AAO) membrane (denoted as PITC@AAO). The fluorescence of the PITC@AAO membrane is obviously enhanced after titrating the analyte PCB101 into the membrane, being ascribed to the halogen-bonding interaction between the fluorophore PITC and the analyte PCB101. The fluorescence intensity increases with the PCB101 concentration in the low range below 1 ppm, and there exists an approximate linear relationship between the relative fluorescence intensity and the PCB101 concentration in the low range of 1-6 ppb. Moreover, the PITC@AAO membrane shows good selectivity; for example, it is insensitive to common structural analogs (polychlorinated aromatics). The mechanisms of the fluorescence enhancement and the better sensitivity and selectivity of the PITC@AAO membrane to PCB101 than that of PITC/n-hexane solution are also discussed. This work demonstrates that trace (in ppb range) PCBs can be detected by simple fluorescence measurement.

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.

Sensitive and selective determination of Cu2+ at D-penicillamine functionalized nano-cellulose modified pencil graphite electrode

NASA Astrophysics Data System (ADS)

Taheri, M.; Ahour, F.; Keshipour, S.

2018-06-01

A novel electrochemical sensor based on D-penicillamine anchored nano-cellulose (DPA-NC) modified pencil graphite electrode was fabricated and used for highly selective and sensitive determination of copper (II) ions in the picomolar concentration by square wave adsorptive stripping voltammetric (SWV) method. The modified electrode showed better and increased SWV response compared to the bare and NC modified electrodes which may be related to the porous structure of modifier along with formation of complex between Cu2+ ions and nitrogen or oxygen containing groups in DPA-NC. Optimization of various experimental parameters influence the performance of the sensor, were investigated. Under optimized condition, DPA-NC modified electrode was used for the analysis of Cu2+ in the concentration range from 0.2 to 50 pM, and a lower detection limit of 0.048 pM with good stability, repeatability, and selectivity. Finally, the practical applicability of DPA-NC-PGE was confirmed via measuring trace amount of Cu (II) in tap and river water samples.

Biogenic unmodified gold nanoparticles for selective and quantitative detection of cerium using UV-vis spectroscopy and photon correlation spectroscopy (DLS).

PubMed

Priyadarshini, E; Pradhan, N; Panda, P K; Mishra, B K

2015-06-15

The ability of self-functionalized biogenic GNPs towards highly selective colorimetric detection of rare earth element cerium is being reported for the first time. GNPs underwent rapid aggregation on addition of cerium indicated by red shift of SPR peak followed by complete precipitation. Hereby, this concept of co-ordination of cerium ions onto the GNP surface has been utilized for detection of cerium. The remarkable capacity of GNPs to sensitively detect Ce without proves beneficial compared to previous reports of colorimetric sensing. MDL was 15 and 35 ppm by DLS and UV-vis spectroscopy respectively, suggesting DLS to be highly sensitive and a practical alternative in ultrasensitive detection studies. The sensing system showed a good linear fit favouring feasible detection of cerium in range of 2-50 ppm. Similar studies further showed the superior selectivity of biogenic GNPs compared to chemically synthesized counterparts. The sensing system favours on-site analysis as it overcomes need of complex instrumentation, lengthy protocols and surface modification of GNP. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of the “Highly Sensitive Dog” questionnaire to evaluate the personality dimension “Sensory Processing Sensitivity” in dogs

PubMed Central

Asher, Lucy; Furrer, Sibylle; Lechner, Isabel; Würbel, Hanno; Melotti, Luca

2017-01-01

In humans, the personality dimension ‘sensory processing sensitivity (SPS)’, also referred to as “high sensitivity”, involves deeper processing of sensory information, which can be associated with physiological and behavioral overarousal. However, it has not been studied up to now whether this dimension also exists in other species. SPS can influence how people perceive the environment and how this affects them, thus a similar dimension in animals would be highly relevant with respect to animal welfare. We therefore explored whether SPS translates to dogs, one of the primary model species in personality research. A 32-item questionnaire to assess the “highly sensitive dog score” (HSD-s) was developed based on the “highly sensitive person” (HSP) questionnaire. A large-scale, international online survey was conducted, including the HSD questionnaire, as well as questions on fearfulness, neuroticism, “demographic” (e.g. dog sex, age, weight; age at adoption, etc.) and “human” factors (e.g. owner age, sex, profession, communication style, etc.), and the HSP questionnaire. Data were analyzed using linear mixed effect models with forward stepwise selection to test prediction of HSD-s by the above-mentioned factors, with country of residence and dog breed treated as random effects. A total of 3647 questionnaires were fully completed. HSD-, fearfulness, neuroticism and HSP-scores showed good internal consistencies, and HSD-s only moderately correlated with fearfulness and neuroticism scores, paralleling previous findings in humans. Intra- (N = 447) and inter-rater (N = 120) reliabilities were good. Demographic and human factors, including HSP score, explained only a small amount of the variance of HSD-s. A PCA analysis identified three subtraits of SPS, comparable to human findings. Overall, the measured personality dimension in dogs showed good internal consistency, partial independence from fearfulness and neuroticism, and good intra- and inter-rater reliability, indicating good construct validity of the HSD questionnaire. Human and demographic factors only marginally affected the HSD-s suggesting that, as hypothesized for human SPS, a genetic basis may underlie this dimension within the dog species. PMID:28520773

Polyaniline nanowires-gold nanoparticles hybrid network based chemiresistive hydrogen sulfide sensor

NASA Astrophysics Data System (ADS)

Shirsat, Mahendra D.; Bangar, Mangesh A.; Deshusses, Marc A.; Myung, Nosang V.; Mulchandani, Ashok

2009-02-01

We report a sensitive, selective, and fast responding room temperature chemiresistive sensor for hydrogen sulfide detection and quantification using polyaniline nanowires-gold nanoparticles hybrid network. The sensor was fabricated by facile electrochemical technique. Initially, polyaniline nanowires with a diameter of 250-320 nm bridging the gap between a pair of microfabricated gold electrodes were synthesized using templateless electrochemical polymerization using a two step galvanostatic technique. Polyaniline nanowires were then electrochemically functionalized with gold nanoparticles using cyclic voltammetry technique. These chemiresistive sensors show an excellent limit of detection (0.1 ppb), wide dynamic range (0.1-100 ppb), and very good selectivity and reproducibility.

Highly selective and sensitive simple sensor based on electrochemically treated nano polypyrrole-sodium dodecyl sulphate film for the detection of para-nitrophenol.

PubMed

Arulraj, Abraham Daniel; Vijayan, Muthunanthevar; Vasantha, Vairathevar Sivasamy

2015-10-29

An ultrasensitive and highly selective electrochemical sensor for the determination of p-nitrophenol (p-NP) was developed based on electrochemically treated nano polypyrrole/sodium dodecyl sulphate film (ENPPy/SDS film) modified glassy carbon electrode. The nano polypyrrole/sodium dodecyl sulphate film (NPPy/SDS film) was prepared and treated electrochemically in phosphate buffer solution. The surface morphology and elemental analysis of treated and untreated NPPy/SDS film were characterized by FESEM and EDX analysis, respectively. Wettability of polymer films were analysed by contact angle test. The hydrophilic nature of the polymer film decreased after electrochemical treatment. Effect of the pH of electrolyte and thickness of the ENPPy/SDS film on determination of p-NP was optimised by cyclic voltammetry. Under the optimised conditions, the p-NP was determined from the oxidation peak of p-hydroxyaminophenol which was formed from the reduction of p-NP in the reduction segment of cyclic voltammetry. A very good linear detection range (from 0.1 nM to 100 μM) and the best LOD (0.1 nM) were obtained for p-NP with very good selectivity. This detection limit is below to the allowed limit in drinking water, 0.43 μM, proposed by the U.S. Environmental Protection Agency (EPA) and earlier reports. Moreover, ENPPy/SDS film based sensor exhibits high sensitivity (4.4546 μA μM(-1)) to p-NP. Experimental results show that it is a fast and simple sensor for p-NP. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of five selective media for the detection of Pseudomonas aeruginosa using a strain panel from clinical, environmental and industrial sources.

PubMed

Weiser, Rebecca; Donoghue, Denise; Weightman, Andrew; Mahenthiralingam, Eshwar

2014-04-01

Isolation and correct identification of the opportunistic pathogen and industrial contaminant Pseudomonas aeruginosa are very important and numerous selective media are available for this purpose. A novel comparison of five selective media having positive (acetamide-based agars), negative (Pseudomonas CN selective agar [Oxoid Ltd.] and Pseudomonas Isolation agar [Sigma-Aldrich Company Ltd.]) and chromogenic (chromID® P. aeruginosa [bioMérieux]) selection strategies was performed using a systematically designed bacterial test panel (58 P. aeruginosa and 90 non-P. aeruginosa strains including those commonly misidentified as P. aeruginosa by culture-dependent techniques). Standardised inocula were added to the selective media and the results were recorded after 24 and 72h. After 72h of incubation at 37°C chromID® P. aeruginosa displayed the highest specificity (70%) and had good sensitivity (95%), although the sensitivity was negatively impacted by the large variation in colour of P. aeruginosa colonies, which hampered interpretation. Both media containing inhibitory selective agents performed very similarly, both having 100% sensitivity and a specificity of approximately 30%. Raising the incubation temperature to 42°C increased the specificity of Pseudomonas CN selective agar and Pseudomonas isolation agar (61% and 47% respectively after 72h), but increased the number of false positives encountered with the chromogenic medium, decreasing its specificity to 68% after 72h. Growth on the acetamide agars was weak for all strains and it was often difficult to determine whether true growth had occurred. This, compounded by the low specificity of the acetamide agars (<26%), suggested they were less suitable for application to clinical or industrial settings without further modification. Overall, the chromogenic agar was the most selective but further consideration is required to optimise interpretation of results. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessment of the nutritional status of Nigerian rural children and mothers' perceptions of quality of life.

PubMed

Ojofeitimi, E O

1984-01-01

One hundred and fourteen preschool school children and their 30 mothers from three selected villages in Ile-Ife, Nigeria were assessed for nutritional status using selected and sensitive anthropometric techniques. The mothers' dietary patterns, their perceptions as to components of a good quality of life, infants' immunization status and major cause of infant death were also examined. Approximately 56% of the children and 80% of the women were identified to be suffering from mild to moderate malnutrition. The major cause of infant death as reported by the mothers was high fever and convulsion. Practically all the children under 3 years had not received any form of immunization. Ability to have plenty of children, good health and money, were highly perceived as measures of essential components of quality of life by all the mothers, while 20% listed good feeding, housing, clothing, and only 7% listed potable water. The need for effective health services, regular home visits, supplementary feeding programmes for school children and an effective health education campaign on the importance of immunization and nutrition for rural people are discussed. The training of agricultural extension workers in the use of simple anthropometric techniques to identify covert malnutrition is also highlighted.

Dopamine fluorescent sensors based on polypyrrole/graphene quantum dots core/shell hybrids.

PubMed

Zhou, Xi; Ma, Peipei; Wang, Anqi; Yu, Chenfei; Qian, Tao; Wu, Shishan; Shen, Jian

2015-02-15

A facilely prepared fluorescent sensor was developed for dopamine (DA) detection with high sensitivity and selectivity based on polypyrrole/graphene quantum dots (PPy/GQDs) core/shell hybrids. The composites exhibit strong fluorescence emission, which is dramatically enhanced as high as three times than pristine GQDs. The prepared sensor allows a highly sensitive determination of DA by fluorescent intensity decreasing with the addition of DA and presents a good linearity in range of 5-8000 nM with the detection limit of 10 pM (S/N = 3). Furthermore, the application of the proposed approach have been demonstrated in real samples and showed promise in diagnostic purposes. Copyright © 2014 Elsevier B.V. All rights reserved.

Oxygen measurement by multimode diode lasers employing gas correlation spectroscopy.

PubMed

Lou, Xiutao; Somesfalean, Gabriel; Chen, Bin; Zhang, Zhiguo

2009-02-10

Multimode diode laser (MDL)-based correlation spectroscopy (COSPEC) was used to measure oxygen in ambient air, thereby employing a diode laser (DL) having an emission spectrum that overlaps the oxygen absorption lines of the A band. A sensitivity of 700 ppm m was achieved with good accuracy (2%) and linearity (R(2)=0.999). For comparison, measurements of ambient oxygen were also performed by tunable DL absorption spectroscopy (TDLAS) technique employing a vertical cavity surface emitting laser. We demonstrate that, despite slightly degraded sensitivity, the MDL-based COSPEC-based oxygen sensor has the advantages of high stability, low cost, ease-of-use, and relaxed requirements in component selection and instrument buildup compared with the TDLAS-based instrument.

A new nanobiosensor for glucose with high sensitivity and selectivity in serum based on fluorescence resonance Energy transfer (FRET) between CdTe quantum dots and Au nanoparticles.

PubMed

Tang, Bo; Cao, Lihua; Xu, Kehua; Zhuo, Linhai; Ge, Jiechao; Li, Qingling; Yu, Lijuan

2008-01-01

A novel assembled nanobiosensor QDs-ConA-beta-CDs-AuNPs was designed for the direct determination of glucose in serum with high sensitivity and selectivity. The sensing approach is based on fluorescence resonance energy transfer (FRET) between CdTe quantum dots (QDs) as an energy donor and gold nanoparticles (AuNPs) as an energy acceptor. The specific combination of concanavalin A (ConA)-conjugated QDs and thiolated beta-cyclodextrins (beta-SH-CDs)-modified AuNPs assembles a hyperefficient FRET nanobiosensor. In the presence of glucose, the AuNPs-beta-CDs segment of the nanobiosensor is displaced by glucose which competes with beta-CDs on the binding sites of ConA, resulting in the fluorescence recovery of the quenched QDs. Experimental results show that the increase in fluorescence intensity is proportional to the concentration of glucose within the range of 0.10-50 muM under the optimized experimental conditions. In addition, the nanobiosensor has high sensitivity with a detection limit as low as 50 nM, and has excellent selectivity for glucose over other sugars and most biological species present in serum. The nanobiosensor was applied directly to determine glucose in normal adult human serum, and the recovery and precision of the method were satisfactory. The unique combination of high sensitivity and good selectivity of this biosensor indicates its potential for the clinical determination of glucose directly and simply in serum, and provides the possibility to detect low levels of glucose in single cells or bacterial cultures. Moreover, the designed nanobiosensor achieves direct detection in biological samples, suggesting the use of nanobiotechnology-based assembled sensors for direct analytical applications in vivo or in vitro.

Grating test of contrast sensitivity in patients with Minamata disease.

PubMed Central

Mukuno, K; Ishikawa, S; Okamura, R

1981-01-01

Thirty cases of Minamata disease caused by methyl mercury poisoning with the lesion mainly at the occipital cortex were selected and their spatial contrast sensitivity of vision was examined by the Arden grating chart. At the same time their visual acuity, visual field, and visual evoked cortical potential (VECP) were also investigated. In all cases the results of the Arden test indicated abnormality. Poor results were obtained at higher frequencies of the gratings. VECP elicited by grating pattern reversal stimulus was undertaken in 12 cases out of the 30. The results revealed abnormality almost equal to that shown by the Arden test. Seven out of the 12 cases showed no VECP response. The other 5, giving a response, showed abnormality: when the size of the grating became smaller at higher frequencies, the VECP paused or was not recorded, whereas at low frequencies it was recorded. This finding was in good agreement or was not recorded, whereas at low frequencies it was recorded. This finding was in good agreement with the results of the Arden test. Visual acuity and visual field tests were less sensitive in detecting abnormality. The Arden chart is a sensitive clinical tool for patients with lesions at the cerebral cortex. Furthermore, the test can be used for screening patients who may have come in contrast with organic mercury. PMID:7236573

Interrater Reliability and Diagnostic Performance of Subjective Evaluation of Sublingual Microcirculation Images by Physicians and Nurses: A Multicenter Observational Study.

PubMed

Lima, Alexandre; López, Alejandra; van Genderen, Michel E; Hurtado, Francisco Javier; Angulo, Martin; Grignola, Juan C; Shono, Atsuko; van Bommel, Jasper

2015-09-01

This was a cross-sectional multicenter study to investigate the ability of physicians and nurses from three different countries to subjectively evaluate sublingual microcirculation images and thereby discriminate normal from abnormal sublingual microcirculation based on flow and density abnormalities. Forty-five physicians and 61 nurses (mean age, 36 ± 10 years; 44 males) from three different centers in The Netherlands (n = 61), Uruguay (n = 12), and Japan (n = 33) were asked to subjectively evaluate a sample of 15 microcirculation videos randomly selected from an experimental model of endotoxic shock in pigs. All videos were first analyzed offline using the A.V.A. software by an independent, experienced investigator and were categorized as good, bad, or very bad microcirculation based on the microvascular flow index, perfused capillary density, and proportion of perfused capillaries. Then, the videos were randomly assigned to the examiners, who were instructed to subjectively categorize each image as good, bad, or very bad. An interrater analysis was performed, and sensitivity and specificity tests were calculated to evaluate the proportion of A.V.A. score abnormalities that the examiners correctly identified. The κ statistics indicated moderate agreement in the evaluation of microcirculation abnormalities using three categories, i.e., good, bad, or very bad (κ = 0.48), and substantial agreement using two categories, i.e., normal (good) and abnormal (bad or very bad) (κ = 0.66). There was no significant difference between the κ three and κ two statistics. We found that the examiner's subjective evaluations had good diagnostic performance and were highly sensitive (84%; 95% confidence interval, 81%-86%) and specific (87%; 95% confidence interval, 84%-90%) for sublingual microcirculatory abnormalities as assessed using the A.V.A. software. The subjective evaluations of sublingual microcirculation by physicians and nurses agreed well with a conventional offline analysis and were highly sensitive and specific for sublingual microcirculatory abnormalities.

m-Cresol purple functionalized surface enhanced Raman scattering paper chips for highly sensitive detection of pH in the neutral pH range.

PubMed

Zou, Xinxin; Wang, Yunqing; Liu, Wanhui; Chen, Lingxin

2017-06-26

Herein, a pH sensitive paper SERS chip was prepared by selecting m-cresol purple, a molecule with halochromic properties in the neutral pH range as a Raman reporter. The adsorbed m-cresol purple underwent a reversible change in its electronic configuration from a non-resonant species to a resonant species, which resulted in a significant Raman signal intensity variation due to the transformation of the sensing mode from SERS to surface-enhanced resonance Raman scattering (SERRS). The chips have a sensitive pH range of 6.0 to 8.0 and exhibited good performance for the detection of natural water samples with detection precision of approximately 0.03 pH units, suggesting great potential for environmental pH monitoring applications.

SPR based hybrid electro-optic biosensor for β-lactam antibiotics determination in water

NASA Astrophysics Data System (ADS)

Galatus, Ramona; Feier, Bogdan; Cristea, Cecilia; Cennamo, Nunzio; Zeni, Luigi

2017-09-01

The present work aims to provide a hybrid platform capable of complementary and sensitive detection of β-lactam antibiotics, ampicillin in particular. The use of an aptamer specific to ampicillin assures good selectivity and sensitivity for the detection of ampicillin from different matrice. This new approach is dedicated for a portable, remote sensing platform based on low-cost, small size and low-power consumption solution. The simple experimental hybrid platform integrates the results from the D-shape surface plasmon resonance plastic optical fiber (SPR-POF) and from the electrochemical (bio)sensor, for the analysis of ampicillin, delivering sensitive and reliable results. The SPR-POF already used in many previous applications is embedded in a new experimental setup with fluorescent fibers emitters, for broadband wavelength analysis, low-power consumption and low-heating capabilities of the sensing platform.

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.

Review of the frequency stabilization of TEA CO2 laser oscillators

NASA Technical Reports Server (NTRS)

Willetts, David V.

1987-01-01

Most applications of TEA CO2 lasers in heterodyne radar systems require that the transmitter has a high degree of frequency stability. This ensures good Doppler resolution and maximizes receiver sensitivity. However, the environment within the device is far from benign with fast acoustic and electrical transients being present. Consequently the phenomena which govern the frequency stability of pulsed lasers are quite different from those operative in their CW counterparts. This review concentrates on the mechanisms of chirping within the output pulse; pulse to pulse frequency drift may be eliminated by frequency measurement and correction on successive pulses. It emerges that good stability hinges on correct cavity design. The energy-dependent laser-induced frequency sweep falls dramatically as mode diameter is increased. Thus, it is necessary to construct resonators with good selectivity for single mode operation while having a large spot size.

Mango core inner shell membrane template-directed synthesis of porous ZnO films and their application for enzymatic glucose biosensor

NASA Astrophysics Data System (ADS)

Zhou, Yu; Wang, Lei; Ye, Zhizhen; Zhao, Minggang; Cai, Hui; Huang, Jingyun

2013-11-01

Micro/nano-porous ZnO films were synthesized through a simple biotemplate-directed method using mango core inner shell membranes as templates. The achieved ZnO films with wrinkles on the surface are combined of large holes and small pores in the bulk. High specific surface area, numerous microspaces, and small channels for fluid circulation provided by this unique structure along with the good biocompatibility and electron communication features of ZnO material make the product an ideal platform for the immobilization of enzymes The fabricated glucose biosensor based on the porous ZnO films exhibits good selective detection ability of analyte with good stability, high sensitivity of 50.58 μA cm-2 mM-1 and a wide linear range of 0.2-5.6 mM along with a low detection limit of 10 μM.

A cascaded QSAR model for efficient prediction of overall power conversion efficiency of all-organic dye-sensitized solar cells.

PubMed

Li, Hongzhi; Zhong, Ziyan; Li, Lin; Gao, Rui; Cui, Jingxia; Gao, Ting; Hu, Li Hong; Lu, Yinghua; Su, Zhong-Min; Li, Hui

2015-05-30

A cascaded model is proposed to establish the quantitative structure-activity relationship (QSAR) between the overall power conversion efficiency (PCE) and quantum chemical molecular descriptors of all-organic dye sensitizers. The cascaded model is a two-level network in which the outputs of the first level (JSC, VOC, and FF) are the inputs of the second level, and the ultimate end-point is the overall PCE of dye-sensitized solar cells (DSSCs). The model combines quantum chemical methods and machine learning methods, further including quantum chemical calculations, data division, feature selection, regression, and validation steps. To improve the efficiency of the model and reduce the redundancy and noise of the molecular descriptors, six feature selection methods (multiple linear regression, genetic algorithms, mean impact value, forward selection, backward elimination, and +n-m algorithm) are used with the support vector machine. The best established cascaded model predicts the PCE values of DSSCs with a MAE of 0.57 (%), which is about 10% of the mean value PCE (5.62%). The validation parameters according to the OECD principles are R(2) (0.75), Q(2) (0.77), and Qcv2 (0.76), which demonstrate the great goodness-of-fit, predictivity, and robustness of the model. Additionally, the applicability domain of the cascaded QSAR model is defined for further application. This study demonstrates that the established cascaded model is able to effectively predict the PCE for organic dye sensitizers with very low cost and relatively high accuracy, providing a useful tool for the design of dye sensitizers with high PCE. © 2015 Wiley Periodicals, Inc.

Supramolecular recognition control of polyethylene glycol modified N-doped graphene quantum dots: tunable selectivity for alkali and alkaline-earth metal ions.

PubMed

Yang, Siwei; Sun, Jing; Zhu, Chong; He, Peng; Peng, Zheng; Ding, Guqiao

2016-02-07

The graphene quantum dot based fluorescent probe community needs unambiguous evidence about the control on the ion selectivity. In this paper, polyethylene glycol modified N-doped graphene quantum dots (PN-GQDs) were synthesized by alkylation reaction between graphene quantum dots and organic halides. We demonstrate the tunable selectivity and sensitivity by controlling the supramolecular recognition through the length and the end group size of the polyether chain on PN-GQDs. The relationship formulae between the selectivity/detection limit and polyether chains are experimentally deduced. The polyether chain length determines the interaction between the PN-GQDs and ions with different ratios of charge to radius, which in turn leads to a good selectivity control. Meanwhile the detection limit shows an exponential growth with the size of end groups of the polyether chain. The PN-GQDs can be used as ultrasensitive and selective fluorescent probes for Li(+), Na(+), K(+), Mg(2+), Ca(2+) and Sr(2+), respectively.

The mid-IR silicon photonics sensor platform (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kimerling, Lionel; Hu, Juejun; Agarwal, Anuradha M.

2017-02-01

Advances in integrated silicon photonics are enabling highly connected sensor networks that offer sensitivity, selectivity and pattern recognition. Cost, performance and the evolution path of the so-called `Internet of Things' will gate the proliferation of these networks. The wavelength spectral range of 3-8um, commonly known as the mid-IR, is critical to specificity for sensors that identify materials by detection of local vibrational modes, reflectivity and thermal emission. For ubiquitous sensing applications in this regime, the sensors must move from premium to commodity level manufacturing volumes and cost. Scaling performance/cost is critically dependent on establishing a minimum set of platform attributes for point, wearable, and physical sensing. Optical sensors are ideal for non-invasive applications. Optical sensor device physics involves evanescent or intra-cavity structures for applied to concentration, interrogation and photo-catalysis functions. The ultimate utility of a platform is dependent on sample delivery/presentation modalities; system reset, recalibration and maintenance capabilities; and sensitivity and selectivity performance. The attributes and performance of a unified Glass-on-Silicon platform has shown good prospects for heterogeneous integration on materials and devices using a low cost process flow. Integrated, single mode, silicon photonic platforms offer significant performance and cost advantages, but they require discovery and qualification of new materials and process integration schemes for the mid-IR. Waveguide integrated light sources based on rare earth dopants and Ge-pumped frequency combs have promise. Optical resonators and waveguide spirals can enhance sensitivity. PbTe materials are among the best choices for a standard, waveguide integrated photodetector. Chalcogenide glasses are capable of transmitting mid-IR signals with high transparency. Integrated sensor case studies of i) high sensitivity analyte detection in solution; ii) gas sensing in air and iii) on-chip spectrometry provide good insight into the tradeoffs being made en route to ubiquitous sensor deployment in an Internet of Things.

A Two-Domain Self-Report Measure of Periodontal Disease Has Good Accuracy for Periodontitis Screening in Dental School Outpatients.

PubMed

Chatzopoulos, Georgios S; Tsalikis, Lazaros; Konstantinidis, Antonios; Kotsakis, Georgios A

2016-10-01

The assessment of periodontitis and treatment needs is primarily based on clinical and radiographic examinations. Albeit effective in predicting treatment needs, these examinations are costly, time-consuming, and impractical for assessing population-level needs. The purpose of the present study is to evaluate a two-domain self-report questionnaire for rapid periodontitis screening. Six hundred white adult individuals, dentate or partially dentate and seeking dental therapy at a university clinic, underwent oral examination utilizing the full-mouth Community Periodontal Index of Treatment Needs (CPITN). To assess predictive value of self-reported periodontal measures (SRPMs) for periodontitis screening, four questions were formulated. Two questions aimed to assess "dentist-diagnosed periodontal disease" and two inquired about "self-assessed periodontitis." Multiple logistic regression models were used to construct receiver-operating characteristic curves, and predictor selection was performed via a forward stepwise selection process. Five hundred thirty-five volunteers with a mean age of 50.1 years elected to respond to SRPMs via telephone interview. After oral examination, 17.8% of participants were assessed as having CPITN = 4, representing compromised periodontal status. Sensitivity and specificity for correctly classifying compromised periodontal status ranged from 5.3% to 72.6%, and 87.8% to 99.5% for individual SRPMs. Sensitivity and specificity were increased when combining a measure of self-assessed periodontal disease and a measure of dentist-diagnosed disease as predictors. Addition of age and sex maximized sensitivity/specificity at 82.1%/82.2%. Diabetic status, smoking, and body mass index did not enhance the prediction. A two-domain self-report measure combining two self-report items with age and sex has good sensitivity and specificity for periodontitis screening in a white, university-based population. The proposed self-report measure can be valuable for periodontitis screening in resource-limited settings where gold standard clinical examination may not be pragmatic. Further validation studies are required to assess whether findings from this study are context-specific.

Highly sensitive oligothiophene-phenylamine-based dual-functional fluorescence "turn-on" sensor for rapid and simultaneous detection of Al3+ and Fe3+ in environment and food samples.

PubMed

Guo, Zongrang; Niu, Qingfen; Li, Tianduo

2018-07-05

Developing low-cost and efficient sensors for rapid, selective and sensitive detection of the transition metal ions in environmental and food science is very important. In this study, a novel dual-functional fluorescent "turn-on" sensor 3TP based on oligothiophene-phenylamine Schiff base has been synthesized for discrimination and simultaneous detection of both Al 3+ and Fe 3+ ions with high selectivity and anti-interference over other metal ions. Sensor 3TP displayed a very fast fluorescence-enhanced response towards Al 3+ and Fe 3+ ions with low detection limits (0.177μM for Al 3+ and 0.172μM for Fe 3+ ) and wide pH response range (4.0-12.0). The Al 3+ /Fe 3+ sensing mechanisms were investigated by fluorescence experiments, 1 H NMR titrations, FT-IR and ESI-MS spectra. Importantly, sensor 3TP was served as an efficient solid material for the highly sensitive and selective detection of Fe 3+ on TLC plates. Moreover, the sensor 3TP has been successfully used to detect trace Al 3+ and Fe 3+ in environment and food samples with satisfactory results and good recoveries, revealing a convenient, reliable and accurate method for Al 3+ and Fe 3+ analysis in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Label free selective detection of estriol using graphene oxide-based fluorescence sensor

NASA Astrophysics Data System (ADS)

Kushwaha, H. S.; Sao, Reshma; Vaish, Rahul

2014-07-01

Water-soluble and fluorescent Graphene oxide (GO) is biocompatible, easy, and economical to synthesize. Interestingly, GO is also capable of quenching fluorescence. On the basis of its fluorescence and quenching abilities, GO has been reported to serve as an energy acceptor in a fluorescence resonance energy transfer (FRET) sensor. GO-based FRET biosensors have been widely reported for sensing of proteins, nucleic acid, ATP (Adenosine triphosphate), etc. GO complexes with fluorescent dyes and enzymes have been used to sense metal ions. Graphene derivatives have been used for sensing endocrine-disrupting chemicals like bisphenols and chlorophenols with high sensitivity and good reproducibility. On this basis, a novel GO based fluorescent sensor has been successfully designed to detect estriol with remarkable selectivity and sensitivity. Estriol is one of the three estrogens in women and is considered to be medically important. Estriol content of maternal urine or plasma acts as an important screening marker for estimating foetal growth and development. In addition, estriol is also used as diagnostic marker for diseases like breast cancer, osteoporosis, neurodegenerative and cardiovascular diseases, insulin resistance, lupus erythematosus, endometriosis, etc. In this present study, we report for the first time a rapid, sensitive with detection limit of 1.3 nM, selective and highly biocompatible method for label free detection of estriol under physiological conditions using fluorescence assay.

Highly sensitive oligothiophene-phenylamine-based dual-functional fluorescence "turn-on" sensor for rapid and simultaneous detection of Al3+ and Fe3+ in environment and food samples

NASA Astrophysics Data System (ADS)

Guo, Zongrang; Niu, Qingfen; Li, Tianduo

2018-07-01

Developing low-cost and efficient sensors for rapid, selective and sensitive detection of the transition metal ions in environmental and food science is very important. In this study, a novel dual-functional fluorescent "turn-on" sensor 3TP based on oligothiophene-phenylamine Schiff base has been synthesized for discrimination and simultaneous detection of both Al3+ and Fe3+ ions with high selectivity and anti-interference over other metal ions. Sensor 3TP displayed a very fast fluorescence-enhanced response towards Al3+ and Fe3+ ions with low detection limits (0.177 μM for Al3+ and 0.172 μM for Fe3+) and wide pH response range (4.0-12.0). The Al3+/Fe3+ sensing mechanisms were investigated by fluorescence experiments, 1H NMR titrations, FT-IR and ESI-MS spectra. Importantly, sensor 3TP was served as an efficient solid material for the highly sensitive and selective detection of Fe3+ on TLC plates. Moreover, the sensor 3TP has been successfully used to detect trace Al3+ and Fe3+ in environment and food samples with satisfactory results and good recoveries, revealing a convenient, reliable and accurate method for Al3+ and Fe3+ analysis in real samples.

Recyclable colorimetric sensor of Cr3 + and Pb2 + ions simultaneously using a zwitterionic amino acid modified gold nanoparticles

NASA Astrophysics Data System (ADS)

Sang, Fuming; Li, Xin; Zhang, Zhizhou; Liu, Jia; Chen, Guofu

2018-03-01

In this work, a rapid, simple and sensitive colorimetric sensor for simultaneous (or respective) detection of Cr3 + and Pb2 + using tyrosine functionalized gold nanoparticles (AuNPsTyr) has been developed. Tyrosine, a natural and zwitterionic amino acid, could be as a reducing and capping agent to synthesise AuNPs and allow for the simultaneous and selective detection of Cr3 + and Pb2 +. Upon the addition of Cr3 + or Pb2 + (a combination of them), the color of AuNPsTyr solution changes from red to blue grey and the characteristic surface plasmon resonance (SPR) band is red-shifted to 580 nm due to the aggregation of AuNPs. Interestingly, the aggregated AuNPsTyr can be regnerated and recycled by removing Pb2 + and Cr3 +. Even after 3 rounds, AuNPsTyr show almost the same A580 nm / A520 nm value for the assays of Pb2 + and Cr3 +, indicating the good recyclability of the colorimetric sensor. The responding time (within 1 min) and sensitivity of the colorimetric sensor are largely improved after the addition of 0.1 M NaCl. Moreover, the AuNPsTyr aggregated by Cr3 + or Pb2 + (a combination of them) show excellent selectivity compared to other metal ions (Cr3 +, Pb2 +, Fe2 +,Cu2 +,Zn2 +,Cr6 +,Ni2 +,Co2 +,Hg2 +,Mn2 +,Mg2 +,Ca2 +,Cd2 +). More importantly, the developed sensor manifests good stability at room temperature for 3 months, which has been successfully used to determine Cr3 + and Pb2 + in the real water samples with a high sensitivity.

Detection of glycoprotein using fiber optic surface plasmon resonance sensors with boronic acid

NASA Astrophysics Data System (ADS)

Wang, Fang; Zhang, Yang; Liu, Zigeng; Qian, Siyu; Gu, Yiying; Jing, Zhenguo; Sun, Changsen; Peng, Wei

2017-04-01

In this paper, we present a tilted fiber Bragg gratings (TFBG) based surface Plasmon resonance (SPR) label-free sensors with boronic acid derivative (ABA-PBA) as receptor molecule to detect glycoprotein with high sensitivity and selectivity. Tilted fiber Bragg gratings (TFBG) as a near infrared wavelengths detecting element can be able to excite a number of cladding modes whose properties can be detected accurately by measuring the variation of transmitted spectra. A 10° TFBG coated by 50nm gold film was manufactured to stimulate surface plasmon resonance on the surface of the sensor. The sensor was loaded with boronic acid derivative as the recognition molecule which has been widely used in various areas for the recognition matrix of diol-containing biomolecules. The proposed TFBG-SPR sensors exhibit good selectivity and repeatability with the protein concentration sensitivity up to 2.867dB/ (mg/ml) and the limit of detection was 2*10-5g/ml.

Development of a novel pH sensor based upon Janus Green B immobilized on triacetyl cellulose membrane: Experimental design and optimization.

PubMed

Chamkouri, Narges; Niazi, Ali; Zare-Shahabadi, Vali

2016-03-05

A novel pH optical sensor was prepared by immobilizing an azo dye called Janus Green B on the triacetylcellulose membrane. Condition of the dye solution used in the immobilization step, including concentration of the dye, pH, and duration were considered and optimized using the Box-Behnken design. The proposed sensor showed good behavior and precision (RSD<5%) in the pH range of 2.0-10.0. Advantages of this optical sensor include on-line applicability, no leakage, long-term stability (more than 6 months), fast response time (less than 1 min), high selectivity and sensitivity as well as good reversibility and reproducibility. Copyright © 2015. Published by Elsevier B.V.

Development of highly sensitive and selective antibodies for the detection of the explosive pentaerythritol tetranitrate (PETN) by bioisosteric replacement.

PubMed

Hesse, Almut; Biyikal, Mustafa; Rurack, Knut; Weller, Michael G

2016-02-01

An improved antibody against the explosive pentaerythritol tetranitrate (PETN) was developed. The immunogen was designed by the concept of bioisosteric replacement, which led to an excellent polyclonal antibody with extreme selectivity and immunoassays of very good sensitivity. Compounds such as nitroglycerine, 2,4,6-trinitrotoluene, 1,3,5-trinitrobenzene, hexogen (RDX), 2,4,6-trinitroaniline, 1,3-dinitrobenzene, octogen (HMX), triacetone triperoxide, ammonium nitrate, 2,4,6-trinitrophenol and nitrobenzene were tested for potential cross-reactivity. The detection limit of a competitive enzyme-linked immunosorbent assay was determined to be around 0.5 µg/l. The dynamic range of the assay was found to be between 1 and 1000 µg/l, covering a concentration range of three decades. This work shows the successful application of the bioisosteric concept in immunochemistry by exchange of a nitroester to a carbonate diester. The antiserum might be used for the development of quick tests, biosensors, microtitration plate immunoassays, microarrays and other analytical methods for the highly sensitive detection of PETN, an explosive frequently used by terrorists, exploiting the extreme difficulty of its detection. Copyright © 2015 John Wiley & Sons, Ltd.

Construction of novel sensitive electrochemical sensor for electro-oxidation and determination of citalopram based on zinc oxide nanoparticles and multi-walled carbon nanotubes.

PubMed

Ghaedi, Hamed; Afkhami, Abbas; Madrakian, Tayyebeh; Soltani-Felehgari, Farzaneh

2016-02-01

A new chemically modified carbon paste electrode (CMCPE) was applied to the simple, rapid, highly selective and sensitive determination of citalopram in human serum and pharmaceutical preparations using adsorptive square wave voltammetry (ASWV). The ZnO nanoparticles and multi-walled carbon nanotubes modified CPE (ZnO-MWCNT/CPE) electrode was prepared by incorporation of the ZnO nanoparticles and multi-walled carbon nanotubes (MWCNT) in carbon paste electrode. The limit of detection and the linear range were found to be 0.005 and 0.012 to 1.54μmolL(-1) of citalopram, respectively. The effects of potentially interfering substances on the determination of this compound were investigated and found that the electrode is highly selective. The proposed CMCPE was used to the determination of citalopram in human serum, urine and pharmaceutical samples. This reveals that ZnO-MWCNT/CPE shows excellent analytical performance for the determination of citalopram in terms of very low detection limit, high sensitivity, very good repeatability and reproducibility over other methods reported in the literature. Copyright © 2015. Published by Elsevier B.V.

Sulfur and nitrogen binary doped carbon dots derived from ammonium thiocyanate for selective probing doxycycline in living cells and multicolor cell imaging.

PubMed

Xue, Mingyue; Zhang, Liangliang; Zhan, Zhihua; Zou, Mengbing; Huang, Yong; Zhao, Shulin

2016-04-01

A novel sulfur and nitrogen binary doped carbon dots (S,N-CDs) was synthesized by one-step manner through the hydrothermal treatment of citric acid (CA) and ammonium thiocyanate, and the procedures for biomedical applications, including probing doxycycline in living cells and multicolor cell imaging were developed. The obtained S,N-CDs are stable in aqueous solution, possess a very high quantum yield (QY, 74.15%) and good photostability. The fluorescence of S,N-CDs can be specifically quenched by doxycycline, providing a convenient turn-off assay of doxycycline. This assay shows a wide linear detection range from 0.08 to 60 μM with a low detection limit of 20 nM. The present method also displays a good selectivity. More importantly, the S,N-CDs have an excellent biocompatibility and low cytotoxicity, allowing the multicolor cell imaging and doxycycline detection in living cells. Consequently, the developed doxycycline methods is facile, low-cost, biocompatible, sensitive and selective, which may hold the potential applications in the fields of food safety and environmental monitoring, as well as cancer therapy and related mechanism research. Copyright © 2015 Elsevier B.V. All rights reserved.

Bi-enzyme L-arginine-selective amperometric biosensor based on ammonium-sensing polyaniline-modified electrode.

PubMed

Stasyuk, Nataliya; Smutok, Oleh; Gayda, Galina; Vus, Bohdan; Koval'chuk, Yevgen; Gonchar, Mykhailo

2012-01-01

A novel L-arginine-selective amperometric bi-enzyme biosensor based on recombinant human arginase I isolated from the gene-engineered strain of methylotrophic yeast Hansenula polymorpha and commercial urease is described. The biosensing layer was placed onto a polyaniline-Nafion composite platinum electrode and covered with a calcium alginate gel. The developed sensor revealed a good selectivity to L-arginine. The sensitivity of the biosensor was 110 ± 1.3 nA/(mM mm(2)) with the apparent Michaelis-Menten constant (K(M)(app)) derived from an L-arginine (L-Arg) calibration curve of 1.27 ± 0.29 mM. A linear concentration range was observed from 0.07 to 0.6mM, a limit of detection being 0.038 mM and a response time - 10s. The developed biosensor demonstrated good storage stability. A laboratory prototype of the proposed amperometric biosensor was applied to the samples of three commercial pharmaceuticals ("Tivortin", "Cytrarginine", "Aminoplazmal 10% E") for L-Arg testing. The obtained L-Arg-content values correlated well with those declared by producers. Copyright © 2012 Elsevier B.V. All rights reserved.

Photostable and Low-Toxic Yellow-Green Carbon Dots for Highly Selective Detection of Explosive 2,4,6-Trinitrophenol Based on the Dual Electron Transfer Mechanism.

PubMed

Ju, Bo; Wang, Yi; Zhang, Yu-Mo; Zhang, Ting; Liu, Zhihe; Li, Minjie; Xiao-An Zhang, Sean

2018-04-18

Advances in the development of fluorescent carbon dots (CDs) for detecting nitro-explosives have attracted great interest. However, developing long-wavelength luminescence CDs for highly selective determination of 2,4,6-trinitrophenol (TNP) and getting insight into the detection mechanism remain further to be investigated. Here, excitation-independent yellow-green emission CDs with good photostability and low biotoxicity were introduced for detecting TNP selectively. Then, two types of electron transfer (ET) processes including hydrogen-bond interaction-assisted ET and proton transfer-assisted ET are suggested to be responsible for their photophysical behavior. Finally, the visual detection of TNP has been successfully developed by a CD-based indicator paper. The facile, highly sensitive, and selective detection for TNP in both of a solution and a solid phase makes CDs potentially useful in environmental sensor applications.

Selective Determination of Trinitrotoluene Based on Energy Transfer between Carbon Dots and Gold Nanoparticles.

PubMed

Oskoei, Yones Mosaei; Fattahi, Hassan; Hassanzadeh, Javad; Azar, Ali Mousavi

2016-01-01

A fluorescence resonance energy transfer (FRET) system between carbon dots (C-dots) and amine-capped gold nanoparticles (AuNPs) was developed for the selective determination of 2,4,6-trinitrotoluene (TNT). C-dots have an intrinsic florescence emission depending on their exciting wavelength. In the presence of AuNPs, C-dots adsorb on the Au surfaces, and NPs treat as energy acceptor, which can receive light emitted by C-dots, leading to decrease the fluorescence intensity of C-dots. Furthermore, it is observed that nitroaromatic compounds, especially TNT, could restore this fluorescence due to selective interaction with AuNPs via amine groups, and so releasing the C-dots. Based on this effect, a sensitive and selective fluorescence turn-on probe was designed for the determination of TNT. Some important factors including AuNPs and C-dot concentrations and media pH, which would affect the efficiency of the probe, were optimized. Under the optimum experimental conditions, good linear relationships in the range of 7 - 250 nmol L(-1) TNT with the detection limit of 2.2 nmol L(-1) were obtained. The proposed method was satisfactorily applied to the determination of TNT in the environmental water samples. Compared with previous reports, the developed method has relatively high sensitivity, short analysis time, low cost and ease of operation.

Mesoporous carbon nitride based biosensor for highly sensitive and selective analysis of phenol and catechol in compost bioremediation.

PubMed

Zhou, Yaoyu; Tang, Lin; Zeng, Guangming; Chen, Jun; Cai, Ye; Zhang, Yi; Yang, Guide; Liu, Yuanyuan; Zhang, Chen; Tang, Wangwang

2014-11-15

Herein, we reported here a promising biosensor by taking advantage of the unique ordered mesoporous carbon nitride material (MCN) to convert the recognition information into a detectable signal with enzyme firstly, which could realize the sensitive, especially, selective detection of catechol and phenol in compost bioremediation samples. The mechanism including the MCN based on electrochemical, biosensor assembly, enzyme immobilization, and enzyme kinetics (elucidating the lower detection limit, different linear range and sensitivity) was discussed in detail. Under optimal conditions, GCE/MCN/Tyr biosensor was evaluated by chronoamperometry measurements and the reduction current of phenol and catechol was proportional to their concentration in the range of 5.00 × 10(-8)-9.50 × 10(-6)M and 5.00 × 10(-8)-1.25 × 10(-5)M with a correlation coefficient of 0.9991 and 0.9881, respectively. The detection limits of catechol and phenol were 10.24 nM and 15.00 nM (S/N=3), respectively. Besides, the data obtained from interference experiments indicated that the biosensor had good specificity. All the results showed that this material is suitable for load enzyme and applied to the biosensor due to the proposed biosensor exhibited improved analytical performances in terms of the detection limit and specificity, provided a powerful tool for rapid, sensitive, especially, selective monitoring of catechol and phenol simultaneously. Moreover, the obtained results may open the way to other MCN-enzyme applications in the environmental field. Copyright © 2014 Elsevier B.V. All rights reserved.

The Feasibility of Event Sequence Discrimination for the Improvement of Gamma-Ray Spectrometer Sensitivity

DTIC Science & Technology

1989-12-29

1.1.2. General Performance Criteria for Gamma Ray Spectrometers 4 1.1.3. Special Criteria for Space-Based Spectrometer Systems 7 1.1.4. Prior Approaches...calculations were performed for selected incident gamma ray energies and were used to generate tabular and graphical listings of gamma scattering results. The... generated . These output presentations were studied to identify behavior patterns of "good" and "bad" event sequences. For the specific gamma energy

Performance of the ASAS classification criteria for axial and peripheral spondyloarthritis: a systematic literature review and meta-analysis.

PubMed

Sepriano, Alexandre; Rubio, Roxana; Ramiro, Sofia; Landewé, Robert; van der Heijde, Désirée

2017-05-01

To summarise the evidence on the performance of the Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axial spondyloarthritis (axSpA) (also imaging and clinical arm separately), peripheral (p)SpA and the entire set, when tested against the rheumatologist's diagnosis ('reference standard'). A systematic literature review was performed to identify eligible studies. Raw data on SpA diagnosis and classification were extracted or, if necessary, obtained from the authors of the selected publications. A meta-analysis was performed to obtain pooled estimates for sensitivity, specificity, positive and negative likelihood ratios, by fitting random effects models. Nine papers fulfilled the inclusion criteria (N=5739 patients). The entire set of the ASAS SpA criteria yielded a high pooled sensitivity (73%) and specificity (88%). Similarly, good results were found for the axSpA criteria (sensitivity: 82%; specificity: 88%). Splitting the axSpA criteria in 'imaging arm only' and 'clinical arm only' resulted in much lower sensitivity (30% and 23% respectively), but very high specificity was retained (97% and 94% respectively). The pSpA criteria were less often tested than the axSpA criteria and showed a similarly high pooled specificity (87%) but lower sensitivity (63%). Accumulated evidence from studies with more than 5500 patients confirms the good performance of the various ASAS SpA criteria as tested against the rheumatologist's diagnosis. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

A surface enhanced Raman scattering quantitative analytical platform for detection of trace Cu coupled the catalytic reaction and gold nanoparticle aggregation with label-free Victoria blue B molecular probe.

PubMed

Li, Chongning; Ouyang, Huixiang; Tang, Xueping; Wen, Guiqing; Liang, Aihui; Jiang, Zhiliang

2017-01-15

With development of economy and society, there is an urgent need to develop convenient and sensitive methods for detection of Cu 2+ pollution in water. In this article, a simple and sensitive SERS sensor was proposed to quantitative analysis of trace Cu 2+ in water. The SERS sensor platform was prepared a common gold nanoparticle (AuNP)-SiO 2 sol substrate platform by adsorbing HSA, coupling with the catalytic reaction of Cu 2+ -ascorbic acid (H 2 A)-dissolved oxygen, and using label-free Victoria blue B (VBB) as SERS molecular probes. The SERS sensor platform response to the AuNP aggregations by hydroxyl radicals (•OH) oxidizing from the Cu 2+ catalytic reaction, which caused the SERS signal enhancement. Therefore, by monitoring the increase of SERS signal, Cu 2+ in water can be determined accurately. The results show that the SERS sensor platforms owns a linear response with a range from 0.025 to 25μmol/L Cu 2+ , and with a detection limit of 0.008μmol/L. In addition, the SERS method demonstrated good specificity for Cu 2+ , which can determined accurately trace Cu 2+ in water samples, and good recovery and accuracy are obtained for the water samples. With its high selectivity and good accuracy, the sensitive SERS quantitative analysis method is expected to be a promising candidate for determining copper ions in environmental monitoring and food safety. Copyright © 2016 Elsevier B.V. All rights reserved.

The Detection of Protein via ZnO Resonant Raman Scattering Signal

NASA Astrophysics Data System (ADS)

Shan, Guiye; Yang, Guoliang; Wang, Shuang; Liu, Yichun

2008-03-01

Detecting protein with high sensitivity and specificity is essential for disease diagnostics, drug screening and other application. Semiconductor nanoparticles show better properties than organic dye molecules when used as markers for optical measurements. We used ZnO nanoparticles as markers for detecting protein in resonant Raman scattering measurements. The highly sensitive detection of proteins was achieved by an antibody-based sandwich assay. A probe for the target protein was constructed by binding the ZnO/Au nanoparticles to a primary antibody by eletrostatic interaction between Au and the antibody. A secondary antibody, which could be specifically recognized by target protein, was attached to a solid surface. The ZnO/Au-antibody probe could specifically recognize and bind to the complex of the target protein and secondary antibody. Our measurements using the resonant Raman scattering signal of ZnO nanoparticles showed good selectivity and sensitivity for the target protein.

A sensitive LC-MS/MS method for simultaneous determination of amygdalin and paeoniflorin in human plasma and its application.

PubMed

Li, Xiaobing; Shi, Fuguo; Gu, Pan; Liu, Lingye; He, Hua; Ding, Li

2014-04-01

A simple and sensitive HPLC-MS/MS method was developed and fully validated for the simultaneous determination of amygdalin (AD) and paeoniflorin (PF) in human plasma. For both analytes, the method exhibited high sensitivity (LLOQs of 0.6ng/mL) by selecting the ammonium adduct ions ([M+NH4](+)) as the precursor ions and good linearity over the concentration range of 0.6-2000ng/mL with the correlation coefficients>0.9972. The intra- and inter-day precision was lower than 10% in relation to relative standard deviation, while accuracy was within ±2.3% in terms of relative error for both analytes. The developed method was successfully applied to a pilot pharmacokinetic study of AD and PF in healthy volunteers after intravenous infusion administration of Huoxue-Tongluo lyophilized powder for injection. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and Gas Sensing Properties of Single La-Doped SnO2 Nanobelts

PubMed Central

Wu, Yuemei; Zhang, Heng; Liu, Yingkai; Chen, Weiwu; Ma, Jiang; Li, Shuanghui; Qin, Zhaojun

2015-01-01

Single crystal SnO2 nanobelts (SnO2 NBs) and La-SnO2 nanobelts (La-SnO2 NBs) were synthesized by thermal evaporation. Both a single SnO2 NB sensor and a single La-SnO2 NB sensor were developed and their sensing properties were investigated. It is found that the single La-SnO2 NB sensor had a high sensitivity of 8.76 to ethanediol at a concentration of 100 ppm at 230 °C, which is the highest sensitivity of a single SnO2 NB to ethanediol among three kinds of volatile organic (VOC) liquids studied, including ethanediol, ethanol, and acetone. The La-SnO2 NBs sensor also exhibits a high sensitivity, good selectivity and long-term stability with prompt response time to ethanediol. The mechanism behind the enhanced sensing performance of La-doped SnO2 nanobelts is discussed. PMID:26087374

Construction of MoS2/Si nanowire array heterojunction for ultrahigh-sensitivity gas sensor

NASA Astrophysics Data System (ADS)

Wu, Di; Lou, Zhenhua; Wang, Yuange; Xu, Tingting; Shi, Zhifeng; Xu, Junmin; Tian, Yongtao; Li, Xinjian

2017-10-01

Few-layer MoS2 thin films were synthesized by a two-step thermal decomposition process. In addition, MoS2/Si nanowire array (SiNWA) heterojunctions exhibiting excellent gas sensing properties were constructed and investigated. Further analysis reveals that such MoS2/SiNWA heterojunction devices are highly sensitive to nitric oxide (NO) gas under reverse voltages at room temperature (RT). The gas sensor demonstrated a minimum detection limit of 10 ppb, which represents the lowest value obtained for MoS2-based sensors, as well as an ultrahigh response of 3518% (50 ppm NO, ˜50% RH), with good repeatability and selectivity of the MoS2/SiNWA heterojunction. The sensing mechanisms were also discussed. The performance of the MoS2/SiNWA heterojunction gas sensors is superior to previous results, revealing that they have great potential in applications relating to highly sensitive gas sensors.

Determination of complex formation constants by phase sensitive alternating current polarography: Cadmium-polymethacrylic acid and cadmium-polygalacturonic acid.

PubMed

Garrigosa, Anna Maria; Gusmão, Rui; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

2007-10-15

The use of phase sensitive alternating current polarography (ACP) for the evaluation of complex formation constants of systems where electrodic adsorption is present has been proposed. The applicability of the technique implies the previous selection of the phase angle where contribution of capacitive current is minimized. This is made using Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) in the analysis of ACP measurements at different phase angles. The method is checked by the study of the complexation of Cd by polymethacrylic (PMA) and polygalacturonic (PGA) acids, and the optimal phase angles have been ca. -10 degrees for Cd-PMA and ca. -15 degrees for Cd-PGA systems. The goodness of phase sensitive ACP has been demonstrated comparing the determined complex formation constants with those obtained by reverse pulse polarography, a technique that minimizes the electrode adsorption effects on the measured currents.

Construction of MoS2/Si nanowire array heterojunction for ultrahigh-sensitivity gas sensor.

PubMed

Wu, Di; Lou, Zhenhua; Wang, Yuange; Xu, Tingting; Shi, Zhifeng; Xu, Junmin; Tian, Yongtao; Li, Xinjian

2017-10-27

Few-layer MoS 2 thin films were synthesized by a two-step thermal decomposition process. In addition, MoS 2 /Si nanowire array (SiNWA) heterojunctions exhibiting excellent gas sensing properties were constructed and investigated. Further analysis reveals that such MoS 2 /SiNWA heterojunction devices are highly sensitive to nitric oxide (NO) gas under reverse voltages at room temperature (RT). The gas sensor demonstrated a minimum detection limit of 10 ppb, which represents the lowest value obtained for MoS 2 -based sensors, as well as an ultrahigh response of 3518% (50 ppm NO, ∼50% RH), with good repeatability and selectivity of the MoS 2 /SiNWA heterojunction. The sensing mechanisms were also discussed. The performance of the MoS 2 /SiNWA heterojunction gas sensors is superior to previous results, revealing that they have great potential in applications relating to highly sensitive gas sensors.

Chemical reactivation of resin-embedded pHuji adds red for simultaneous two-color imaging with EGFP

PubMed Central

Guo, Wenyan; Liu, Xiuli; Liu, Yurong; Gang, Yadong; He, Xiaobin; Jia, Yao; Yin, Fangfang; Li, Pei; Huang, Fei; Zhou, Hongfu; Wang, Xiaojun; Gong, Hui; Luo, Qingming; Xu, Fuqiang; Zeng, Shaoqun

2017-01-01

The pH-sensitive fluorescent proteins enabling chemical reactivation in resin are useful tools for fluorescence microimaging. EGFP or EYFP is good for such applications. For simultaneous two-color imaging, a suitable red fluorescent protein is an urgent need. Here a pH-sensitive red fluorescent protein, pHuji, is selected and verified to remain pH-sensitive in HM20 resin. We observe 183% fluorescence intensity of pHuji in resin-embeded mouse brain and 29.08-fold fluorescence intensity of reactivated pHuji compared to the quenched state. pHuji and EGFP can be quenched and chemically reactivated simultaneously in resin, thus enabling simultaneous two-color micro-optical sectioning tomography of resin-embedded mouse brain. This method may greatly facilitate the visualization of neuronal morphology and neural circuits to promote understanding of the structure and function of the brain. PMID:28717566

Chemical reactivation of resin-embedded pHuji adds red for simultaneous two-color imaging with EGFP.

PubMed

Guo, Wenyan; Liu, Xiuli; Liu, Yurong; Gang, Yadong; He, Xiaobin; Jia, Yao; Yin, Fangfang; Li, Pei; Huang, Fei; Zhou, Hongfu; Wang, Xiaojun; Gong, Hui; Luo, Qingming; Xu, Fuqiang; Zeng, Shaoqun

2017-07-01

The pH-sensitive fluorescent proteins enabling chemical reactivation in resin are useful tools for fluorescence microimaging. EGFP or EYFP is good for such applications. For simultaneous two-color imaging, a suitable red fluorescent protein is an urgent need. Here a pH-sensitive red fluorescent protein, pHuji, is selected and verified to remain pH-sensitive in HM20 resin. We observe 183% fluorescence intensity of pHuji in resin-embeded mouse brain and 29.08-fold fluorescence intensity of reactivated pHuji compared to the quenched state. pHuji and EGFP can be quenched and chemically reactivated simultaneously in resin, thus enabling simultaneous two-color micro-optical sectioning tomography of resin-embedded mouse brain. This method may greatly facilitate the visualization of neuronal morphology and neural circuits to promote understanding of the structure and function of the brain.

Polymer coated quartz crystal microbalance sensors for detection of volatile organic compounds in gas mixtures.

PubMed

Si, Pengchao; Mortensen, John; Komolov, Alexei; Denborg, Jens; Møller, Preben Juul

2007-08-06

By coating different conducting polymers of thiophene and its derivatives on quartz crystal microbalance (QCM) sensor surfaces, new novel QCM gas sensors have been produced in two simple ways, which could classify testing gas samples of volatile organic compounds (VOCs) gases. Principle components analysis (PCA) has been performed based on the QCM measurement results, which shows that our QCM sensors array has very good utilizing potential on sensing both polar and low-polar/nonpolar VOC gases. The sensitivity, selectivity, reproducibility and detection limit of QCM sensors have also been discussed. Quantitative variation of sensitivity response with the increasing concentration has been studied. (PLS) analysis and prediction of concentrations of single gas in mixtures have been carried out.

Rare Earth Doped High Temperature Ceramic Selective Emitters

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Pal, AnnaMarie; Patton, Martin O.; Jenkins, Phillip P.

1999-01-01

As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

Patient reported outcomes in head and neck cancer: selecting instruments for quality of life integration in clinical protocols.

PubMed

Silveira, Augusta P; Gonçalves, Joaquim; Sequeira, Teresa; Ribeiro, Cláudia; Lopes, Carlos; Monteiro, Eurico; Pimentel, Francisco L

2010-10-31

Health Related Quality of Life has been used in medical research for more than twenty years, being progressively accepted during the last decade as an important patient reported outcome. Considering the multidimensional approach involved in Health Related Quality of Life assessment, instrument applicability and cultural adaptation must be tested for each population. In order to select the most appropriate instrument for Head and Neck cancer patients, two major Health Related Quality of Life specific questionnaires for Head and Neck cancer patients were compared. Conceptual differences, psychometric characteristics, scores, reliability, construct validity and sensitivity to symptomatology, tumour location, tumour size were analyzed. 102 consecutive Head and Neck cancer patients completed two different Health Related Quality of Life questionnaires: EORTC QLQ-C30 and its specific head and neck module QLQ-H&N35 and the Functional Assessment of Cancer Therapy Scales (FACT-H&N). Patients completed the questionnaires, immediately before consultation as a part of the routine evaluation. A greater variability was always found in the EORTC QLC-C30 questionnaire's scores for all comparable domains. Both instruments revealed a good internal consistency and demonstrated to be good tools to distinguish symptomatic patients. The EORTC questionnaires still demonstrated sensitivity to distinguish T3 and T4 staging. Conceptual differences and the psychometric characteristics are discussed. Our results suggest that these two instruments assess different aspects of Health Related Quality of Life - the questionnaires should be used separately and chosen according to the study objectives and methodology. This study emphases the importance in selecting the appropriate tool as a critical success factor in implementing routine Health Related Quality of Life assessment in clinical practice. This decision assumes particularly importance when utilization of results in real time and integration into clinical protocols are considered.

Comparison of intra-aortic computed tomography angiography to conventional angiography in the presurgical visualization of the Adamkiewicz artery: first results in patients with thoracoabdominal aortic aneurysms.

PubMed

Clarençon, Frédéric; Di Maria, Federico; Cormier, Evelyne; Gaudric, Julien; Sourour, Nader; Gabrieli, Joseph; Iosif, Christina; Jenny, Catherine; Koskas, Fabien; Chiras, Jacques

2013-11-01

The aim of this study was to compare the sensitivity of intra-aortic computed tomography angiography (IA-CTA) to that of regular spinal digital subtraction angiography for the presurgical location of the Adamkiewicz artery (AKA). Thirty patients (21 males, 9 females; mean age 64 years) had an IA-CTA for the location of the AKA before surgery of aneurysm (n = 24) or dissection (n = 6) of the thoracoabdominal aorta. After femoral artery puncture, a pigtail catheter was positioned at the origin of the descending aorta. CT acquisition was performed with an intra-aortic iodinated contrast media injection (15 mL/s, 120 mL). The visualization of the AKA and the location of the feeder(s) to the AKA were independently evaluated by two observers. Interrater agreement was calculated using a kappa test. Spinal angiogram by selective catheterization was systematically performed to confirm the results of the IA-CTA. The AKA was visualized by the IA-CTA in 27/30 cases (90 %); in 26/31 (84 %) cases, the continuity with the aorta was satisfactorily seen. Interrater agreement was good for the visualization of the AKA and its feeder(s): 0.625 and 0.87, respectively. In 75 % of the cases for which the AKA was visualized, the selective catheterization confirmed the results of the IA-CTA. In the remaining 25 % of the cases, the selective catheterization could not be performed due to marked vessels' tortuosity or ostium stenosis. IA-CTA is a feasible technique in a daily practice that presents a good sensitivity for the location of the AKA.

Development of a Molecularly Imprinted Polymer-Based Sensor for the Electrochemical Determination of Triacetone Triperoxide (TATP)

PubMed Central

Mamo, Samuel Kassahun; Gonzalez-Rodriguez, Jose

2014-01-01

The explosive triacetone triperoxide (TATP), which can be prepared from commercially readily available reagents following an easy synthetic procedure, is one of the most common components of improvised explosive devices (IEDs). Molecularly-imprinted polymer (MIP) electrochemical sensors have proved useful for the determination of different compounds in different matrices with the required sensitivity and selectivity. In this work, a highly sensitive and selective molecularly imprinted polymer with electrochemical capabilities for the determination of TATP has been developed. The molecular imprinting has been performed via electropolymerisation onto a glassy carbon electrode surface by cyclic voltammetry from a solution of pyrrole functional monomer, TATP template and LiClO4. Differential Pulse Voltammetry of TATP, with LiClO4 as supporting electrolyte, was performed in a potential range of −2.0 V to +1.0 V (vs. Ag/AgCl). Three-factor two-level factorial design was used to optimise the monomer concentration at 0.1 mol·L−1, template concentration at 100 mmol·L−1 and the number of cyclic voltammetry scan cycles to 10. The molecularly imprinted polymer-modified glassy carbon electrode demonstrated good performance at low concentrations for a linear range of 82–44,300 μg·L−1 and a correlation coefficient of r2 = 0.996. The limits of detection (LoD) and quantification (LoQ) achieved were 26.9 μg·L−1 and 81.6 μg·L−1, respectively. The sensor demonstrated very good repeatability with precision values (n = 6, expressed as %RSD) of 1.098% and 0.55% for 1108 and 2216 μg·L−1, respectively. It also proved selective for TATP in the presence of other explosive substances such as PETN, RDX, HMX, and TNT. PMID:25490589

Differential retention of metabolic genes following whole-genome duplication.

PubMed

Gout, Jean-François; Duret, Laurent; Kahn, Daniel

2009-05-01

Classical studies in Metabolic Control Theory have shown that metabolic fluxes usually exhibit little sensitivity to changes in individual enzyme activity, yet remain sensitive to global changes of all enzymes in a pathway. Therefore, little selective pressure is expected on the dosage or expression of individual metabolic genes, yet entire pathways should still be constrained. However, a direct estimate of this selective pressure had not been evaluated. Whole-genome duplications (WGDs) offer a good opportunity to address this question by analyzing the fates of metabolic genes during the massive gene losses that follow. Here, we take advantage of the successive rounds of WGD that occurred in the Paramecium lineage. We show that metabolic genes exhibit different gene retention patterns than nonmetabolic genes. Contrary to what was expected for individual genes, metabolic genes appeared more retained than other genes after the recent WGD, which was best explained by selection for gene expression operating on entire pathways. Metabolic genes also tend to be less retained when present at high copy number before WGD, contrary to other genes that show a positive correlation between gene retention and preduplication copy number. This is rationalized on the basis of the classical concave relationship relating metabolic fluxes with enzyme expression.

Cell-mediated immunity in an ageing population.

PubMed Central

Girard, J P; Paychère, M; Cuevas, M; Fernandes, B

1977-01-01

Eight hundred and eighty patients hospitalized in a geriatric hospital were routinely tested with 2, 10, 30 and 100 i.u. tuberculin. Among these, fifty-four patients were selected on the basis of negative skin tests and absence of evident diseases interfering with the function of the immune apparatus. A battery of tests analysing cell-mediated immunity was applied to those fifty-four patients. It appears that elderly patients having a negative test to 100 i.u. tuberculin show very infrequent sensitization to three other thymus-dependent antigens. The capacity of this selected population to become sensitized to DNCB is poor (20%). Furthermore they exhibit a low per cent of peripheral blood T cells (36%) and a poor capacity to respond in vitro to mitogens such as PHA. Testing the in vitro response to a battery of antigens demonstrates a good correlation with the results of the skin tests. Finally the leucocytes of 25% of this selected population failed to produce LIF in vitro in the presence of PHA. These results suggest not only an absolute decrease in the population of circulating T lymphocytes in those elderly humans; but very likely, at least in some cases, a functional impairment of T cells. PMID:321161

A selectively rhodamine-based colorimetric probe for detecting copper(II) ion.

PubMed

Zhang, Jiangang; Zhang, Li; Wei, Yanli; Chao, Jianbing; Shuang, Shaomin; Cai, Zongwei; Dong, Chuan

2014-11-11

A novel rhodamine derivative 3-bromo-5-methylsalicylaldehyde rhodamine B hydrazone (BMSRH) has been synthesized by reacting rhodamine B hydrazide with 3-bromo-5-methylsalicylaldehyde and developed as a new colorimetric probe for the selective and sensitive detection of Cu2+. Addition of Cu2+ to the solution of BMSRH results in a rapid color change from colorless to red together with an obvious new band appeared at 552 nm in the UV-vis absorption spectra. This change is attributed to the spirocycle form of BMSRH opened via coordination with Cu2+ in a 1:1 stoichiometry and their association constant is determined as 3.2×10(4) L mol(-1). Experimental results indicate that the BMSRH can provide a rapid, selective and sensitive response to Cu2+ with a linear dynamic range 0.667-240 μmol/L. Common interferent ions do not show any interference on the Cu2+ determination. It is anticipated that BMSRH can be a good candidate probe and has potential application for Cu2+ determination. The proposed probe exhibits the following advantages: a quick, simple and facile synthesis. Copyright © 2014 Elsevier B.V. All rights reserved.

An off-on fluorescence probe targeting mitochondria based on oxidation-reduction response for tumor cell and tissue imaging

NASA Astrophysics Data System (ADS)

Yao, Hanchun; Cao, Li; Zhao, Weiwei; Zhang, Suge; Zeng, Man; Du, Bin

2017-10-01

In this study, a tumor-targeting poly( d, l-lactic-co-glycolic acid) (PLGA) loaded "off-on" fluorescent probe nanoparticle (PFN) delivery system was developed to evaluate the region of tumor by off-on fluorescence. The biodegradability of the nanosize PFN delivery system readily released the probe under tumor acidic conditions. The probe with good biocompatibility was used to monitor the intracellular glutathione (GSH) of cancer cells and selectively localize to mitochondria for tumor imaging. The incorporated tumor-targeting probe was based on the molecular photoinduced electron transfer (PET) mechanism preventing fluorescence ("off" state) and could be easily released under tumor acidic conditions. However, the released tumor-targeting fluorescence probe molecule was selective towards GSH with high selectivity and an ultra-sensitivity for the mitochondria of cancer cells and tissues significantly increasing the probe molecule fluorescence signal ("on" state). The tumor-targeting fluorescence probe showed sensitivity to GSH avoiding interference from cysteine and homocysteine. The PFNs could enable fluorescence-guided cancer imaging during cancer therapy. This work may expand the biological applications of PFNs as a diagnostic reagent, which will be beneficial for fundamental research in tumor imaging. [Figure not available: see fulltext.

Computational Analysis of Candidate Disease Genes and Variants for Salt-Sensitive Hypertension in Indigenous Southern Africans

PubMed Central

Tiffin, Nicki; Meintjes, Ayton; Ramesar, Rajkumar; Bajic, Vladimir B.; Rayner, Brian

2010-01-01

Multiple factors underlie susceptibility to essential hypertension, including a significant genetic and ethnic component, and environmental effects. Blood pressure response of hypertensive individuals to salt is heterogeneous, but salt sensitivity appears more prevalent in people of indigenous African origin. The underlying genetics of salt-sensitive hypertension, however, are poorly understood. In this study, computational methods including text- and data-mining have been used to select and prioritize candidate aetiological genes for salt-sensitive hypertension. Additionally, we have compared allele frequencies and copy number variation for single nucleotide polymorphisms in candidate genes between indigenous Southern African and Caucasian populations, with the aim of identifying candidate genes with significant variability between the population groups: identifying genetic variability between population groups can exploit ethnic differences in disease prevalence to aid with prioritisation of good candidate genes. Our top-ranking candidate genes include parathyroid hormone precursor (PTH) and type-1angiotensin II receptor (AGTR1). We propose that the candidate genes identified in this study warrant further investigation as potential aetiological genes for salt-sensitive hypertension. PMID:20886000

Arrhythmia Evaluation in Wearable ECG Devices

PubMed Central

Sadrawi, Muammar; Lin, Chien-Hung; Hsieh, Yita; Kuo, Chia-Chun; Chien, Jen Chien; Haraikawa, Koichi; Abbod, Maysam F.; Shieh, Jiann-Shing

2017-01-01

This study evaluates four databases from PhysioNet: The American Heart Association database (AHADB), Creighton University Ventricular Tachyarrhythmia database (CUDB), MIT-BIH Arrhythmia database (MITDB), and MIT-BIH Noise Stress Test database (NSTDB). The ANSI/AAMI EC57:2012 is used for the evaluation of the algorithms for the supraventricular ectopic beat (SVEB), ventricular ectopic beat (VEB), atrial fibrillation (AF), and ventricular fibrillation (VF) via the evaluation of the sensitivity, positive predictivity and false positive rate. Sample entropy, fast Fourier transform (FFT), and multilayer perceptron neural network with backpropagation training algorithm are selected for the integrated detection algorithms. For this study, the result for SVEB has some improvements compared to a previous study that also utilized ANSI/AAMI EC57. In further, VEB sensitivity and positive predictivity gross evaluations have greater than 80%, except for the positive predictivity of the NSTDB database. For AF gross evaluation of MITDB database, the results show very good classification, excluding the episode sensitivity. In advanced, for VF gross evaluation, the episode sensitivity and positive predictivity for the AHADB, MITDB, and CUDB, have greater than 80%, except for MITDB episode positive predictivity, which is 75%. The achieved results show that the proposed integrated SVEB, VEB, AF, and VF detection algorithm has an accurate classification according to ANSI/AAMI EC57:2012. In conclusion, the proposed integrated detection algorithm can achieve good accuracy in comparison with other previous studies. Furthermore, more advanced algorithms and hardware devices should be performed in future for arrhythmia detection and evaluation. PMID:29068369

Highly sensitive and selective determination of redox states of coenzymes Q9 and Q10 in mice tissues: Application of orbitrap mass spectrometry.

PubMed

Pandey, Renu; Riley, Christopher L; Mills, Edward M; Tiziani, Stefano

2018-06-29

Coenzyme Q (CoQ) is a redox active molecule that plays a fundamental role in mitochondrial energy generation and functions as a potent endogenous antioxidant. Redox ratio of CoQ has been suggested as a good marker of mitochondrial dysfunction and oxidative stress. Nevertheless, simultaneous measurement of redox states of CoQ is challenging owing to its hydrophobicity and instability of the reduced form. In order to improve the analytical methodology, paying special attention to this instability, we developed a highly sensitive and selective high-resolution/accurate-mass (HR/AM) UHPLC-MS/MS method for the rapid determination of redox states of CoQ 9 and CoQ 10 by ultra-performance liquid chromatography-hybrid quadrupole-Orbitrap mass spectrometry. CoQs were extracted using hexane with the addition of butylated hydroxytoluene to limit oxidation during sample preparation. Chromatographic separation of the analytes was achieved on a Kinetex C 18 column with the isocratic elution of 5 mM ammonium formate in 2-propanol/methanol (60:40) within 4 min. A full MS/all ion fragmentation (AIF) acquisition mode with mass accuracy < 5 ppm was used for detection and determination of redox states of CoQ 9 and CoQ 10 in healthy mice tissues using reduced and oxidized CoQ 4 as internal standards. The validated method showed good linearity (r 2  ≥ 0.9991), intraday, inter-day precision (CVs ≤ 11.9%) and accuracy (RE ≤±15.2%). In contrast to existing methods, the current method offers enhanced sensitivity (up to 52 fold) with LOD and LOQ ranged from 0.01 to 0.49 ng mL -1 and 0.04-1.48 ng mL -1 , respectively. Moreover, we evaluated various diluents to investigate bench top stability (at 4 °C) of targeted analytes in tissue samples during LC-MS assay up to 24 h. Ethanol was determined to be an optimum diluent without any significant oxidation of reduced CoQ up to 24 h. The developed method offers a rapid, highly sensitive and selective strategy for the measurement of redox states of CoQs in clinical studies. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of atropine sulfate using a novel sensitive DNA-biosensor based on its interaction on a modified pencil graphite electrode.

PubMed

Ensafi, Ali A; Nasr-Esfahani, Parisa; Heydari-Bafrooei, Esmaeil; Rezaei, B

2015-01-01

A novel, selective, rapid and simple electrochemical method is developed for the determination of atropine sulfate. UV-Vis and differential pulse voltammetry are used to study the interaction of atropine sulfate with salmon sperm ds-DNA on the surface of salmon sperm ds-DNA modified-pencil graphite electrode (PGE). For this purpose, a pencil graphite electrode (PGE) modified with multiwall carbon nanotubes (MWCNTs), titanium dioxide nanoparticles (TiO2NPs), and poly-dialyldimethylammonium chloride (PDDA) decorated with ds-DNA is tested for the determination of atropine sulfate. The electrochemical oxidation peak current of adenine and guanine bonded on the surface of ds-DNA/PDDA-TiO2NPs-MWCNTs/PGE is used to obtain the analytical signal. Decreases in the intensities of guanine and adenine oxidation signals after their interaction with atropine sulfate are used as indicator signals for the sensitive determination of atropine sulfate. Using ds-DNA/PDDA-TiO2NPs-MWCNTs/PGE and based on the guanine signal, linear calibration curves were obtained in the range of 0.6 to 30.0 μmol L(-1) and 30.0 to 600.0 μmol L(-1) atropine sulfate with low detection limits of 30.0 nmol L(-1). The biosensor shows a good selectivity for the determination of atropine sulfate. Finally, the applicability of the biosensor is evaluated by measuring atropine sulfate in real samples with good accuracy. Copyright © 2014 Elsevier B.V. All rights reserved.

Acetone leaf extracts of some South African trees with high activity against Escherichia coli also have good antimycobacterial activity and selectivity index.

PubMed

Elisha, Ishaku L; Botha, Francien S; Madikizela, Balungile; McGaw, Lyndy J; Eloff, Jacobus N

2017-06-19

Tuberculosis is a world-wide problem affecting humans and animals. There is increasing development of resistance of the pathogens to current antimycobacterial agents. Many authors have investigated activities of extracts and isolated compounds from plants. The traditional uses of plants have frequently been the criterion to select plants investigated. In this contribution, we investigate whether plant extracts with very good activity against Escherichia coli may also be active against mycobacteria. The antimycobacterial activity of eight South African tree leaf extracts with high activity against Escherichia coli were determined in vitro against Mycobacterium smegmatis, M. fortuitum and M. aurum, using a serial microdilution method. The cellular cytotoxicity was also determined by the MTT assay using Vero monkey kidney cells. The selectivity index was determined by dividing the cytotoxicity of extracts by MIC. The antimycobacterial activity of the extracts ranged from 0.02 to 2.5 mg/ml. Mycobacterium smegmatis was more sensitive to the extracts (Average MIC = 0.96 mg/ml) and Mycobacterium aurum was comparatively resistant (Average MIC = 2.04 mg/ml). The extracts of Cremaspora triflora had strong antimycobacterial activity with a MIC of 0.05 mg/ml that compared reasonably well with that of streptomycin (0.01 mg/ml) and rifampicin (0.03 mg/ml), p > 0.05. Cremaspora triflora had the best selectivity index of 2.87 against Mycobacterium fortuitum. The high activity of C. triflora extracts against the fast-growing mycobacteria and good cellular safety is promising. It may be interesting to investigate extracts against pathogenic M. tuberculosis, M. bovis and M. avium cultures and to isolate active antimycobacterial compounds.

DEEP U BAND AND R IMAGING OF GOODS-SOUTH: OBSERVATIONS, DATA REDUCTION AND FIRST RESULTS ,

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

Nonino, M.; Cristiani, S.; Vanzella, E.

2009-08-01

We present deep imaging in the U band covering an area of 630 arcmin{sup 2} centered on the southern field of the Great Observatories Origins Deep Survey (GOODS). The data were obtained with the VIMOS instrument at the European Southern Observatory (ESO) Very Large Telescope. The final images reach a magnitude limit U {sub lim} {approx} 29.8 (AB, 1{sigma}, in a 1'' radius aperture), and have good image quality, with full width at half-maximum {approx}0.''8. They are significantly deeper than previous U-band images available for the GOODS fields, and better match the sensitivity of other multiwavelength GOODS photometry. The deepermore » U-band data yield significantly improved photometric redshifts, especially in key redshift ranges such as 2 < z < 4, and deeper color-selected galaxy samples, e.g., Lyman break galaxies at z {approx} 3. We also present the co-addition of archival ESO VIMOS R-band data, with R {sub lim} {approx} 29 (AB, 1{sigma}, 1'' radius aperture), and image quality {approx}0.''75. We discuss the strategies for the observations and data reduction, and present the first results from the analysis of the co-added images.« less

Selective extraction based on poly(MAA-VB-EGMDA) monolith followed by HPLC for determination of hordenine in plasma and urine samples.

PubMed

Chen, Yonggang; Meng, Junhua; Zou, Jili; An, Jing

2015-06-01

Hordenine is an active compound found in several foods, herbs and beer. In this work, a novel sorbent was fabricated for selective solid-phase extraction (SPE) of hordenine in biological samples. The organic polymer sorbent was synthesized in one step in the plastic barrel of a syringe by a pre-polymerization solution consisting of methacrylic acid (MAA), 4-vinylphenylboronic acid (VB) and ethylene glycol dimethacrylate (EGDMA). The conditions for preparation were optimized to generate a poly(MAA-VB-EGMDA) monolith with good permeability. The monolith exhibited good enrichment efficiency towards hordenine. By using tyramine as the internal standard, a poly(MAA-VB-EGMDA)-based SPE-HPLC method was established for analysis of hordenine. Conditions for SPE, including volume of eluting solvent, pH of sample solution, sampling rate and sample volume, were optimized. The proposed SPE-HPLC method presented good linearity (R(2)  = 0.9992) within 10-2000 ng/mL and the detection limits was 3 ng/mL, which is significantly more sensitive than reported methods. The method was also applied in plasma and urine samples; good capability of removing matrices was observed, while hordenine in low content was well extracted and enriched. The recoveries were from 90.6 to 94.7% and from 89.3 to 91.5% for the spiked plasma and urine samples, respectively, with the relative standard deviations <4.7%. Copyright © 2014 John Wiley & Sons, Ltd.

Predictors of long-term renal outcome in lupus nephritis trials: lessons learned from the Euro-Lupus Nephritis cohort.

PubMed

Dall'Era, Maria; Cisternas, Miriam G; Smilek, Dawn E; Straub, Laura; Houssiau, Frédéric A; Cervera, Ricard; Rovin, Brad H; Mackay, Meggan

2015-05-01

There is a need to determine which response measures in lupus nephritis trials are most predictive of good long-term renal function. We used data from the Euro-Lupus Nephritis Trial to evaluate the performance of proteinuria, serum creatinine (Cr), and urinary red blood cells (RBCs) as predictors of good long-term renal outcome. Patients from the Euro-Lupus Nephritis Trial with proteinuria, serum Cr, and urinary RBC measurements at 3, 6, or 12 months and with a minimum of 7 years of followup were included (n = 76). We assessed the ability of these clinical biomarkers at 3, 6, and 12 months after randomization to predict good long-term renal outcome (defined as a serum Cr value ≤1.0 mg/dl) at 7 years. Receiver operating characteristic curves were generated to assess parameter performance at these time points and to select the best cutoff for individual parameters. Sensitivity and specificity were calculated for the parameters alone and in combination. A proteinuria value of <0.8 gm/day at 12 months after randomization was the single best predictor of good long-term renal function (sensitivity 81% and specificity 78%). The addition of serum Cr to proteinuria as a composite predictor did not improve the performance of the outcome measure; addition of urinary RBCs as a predictor significantly decreased the sensitivity to 47%. This study demonstrates that the level of proteinuria at 12 months is the individual best predictor of long-term renal outcome in patients with lupus nephritis. Inclusion of urinary RBCs as part of a composite outcome measure actually undermined the predictive value of the trial data. We therefore suggest that urinary RBCs should not be included as a component of clinical trial response criteria in lupus nephritis. © 2015, American College of Rheumatology.

Surface Plasmon Resonance Investigations of Bioselective Element Based on the Recombinant Protein A for Immunoglobulin Detection

NASA Astrophysics Data System (ADS)

Bakhmachuk, A.; Gorbatiuk, O.; Rachkov, A.; Dons'koi, B.; Khristosenko, R.; Ushenin, I.; Peshkova, V.; Soldatkin, A.

2017-02-01

The developed surface plasmon resonance (SPR) biosensor based on the recombinant Staphylococcal protein A with an additional cysteine residue (SPA-Cys) used as a biorecognition component showed a good selectivity and sensitivity for the immunoglobulin detection. The developed biosensor with SPA-Cys-based bioselective element can also be used as a first step of immunosensor creation. The successful immobilization of SPA-Cys on the nanolayer gold sensor surface of the SPR spectrometer was performed. The efficiency of blocking nonspecific sorption sites on the sensor surface with milk proteins, gelatin, BSA, and HSA was studied, and a rather high efficiency of using gelatin was confirmed. The SPR biosensor selectively interacted with IgG and did not interact with the control proteins. The linear dependence of the sensor response on the IgG concentration in the range from 2 to 10 μg/ml was shown. Using the calibration curve, the IgG concentration was measured in the model samples. The determined concentrations are in good agreement ( r 2 = 0.97) with the given concentration of IgG.

Resistance-associated point mutations in insecticide-insensitive acetylcholinesterase.

PubMed

Mutero, A; Pralavorio, M; Bride, J M; Fournier, D

1994-06-21

Extensive utilization of pesticides against insects provides us with a good model for studying the adaptation of a eukaryotic genome to a strong selective pressure. One mechanism of resistance is the alteration of acetylcholinesterase (EC 3.1.1.7), the molecular target for organophosphates and carbamates. Here, we report the sequence analysis of the Ace gene in several resistant field strains of Drosophila melanogaster. This analysis resulted in the identification of five point mutations associated with reduced sensitivities to insecticides. In some cases, several of these mutations were found to be combined in the same protein, leading to different resistance patterns. Our results suggest that recombination between resistant alleles preexisting in natural populations is a mechanism by which insects rapidly adapt to new selective pressures.

Determination of glyoxal and methylglyoxal in environmental and biological matrices by stir bar sorptive extraction with in-situ derivatization.

PubMed

Neng, N R; Cordeiro, C A A; Freire, A P; Nogueira, J M F

2007-10-26

Stir bar sorptive extraction with in-situ derivatization using 2,3-diaminonaphthalene (DAN) followed by liquid desorption and high performance liquid chromatography with diode array detection (SBSE(DAN)in-situ-LD-HPLC-DAD) was developed for the determination of glyoxal (Gly) and methylglyoxal (MGly) in environmental and biological matrices. DAN proved very good specificity as in-situ derivatising agent for Gly and MGly in aqueous media, allowing the formation of adducts with remarkable sensitivity, selectivity and the absence of photodegradation. Assays performed on spiked (1.0 microg L(-1)) water samples, under convenient experimental conditions, yielded recoveries of 96.2+/-7.9% for Gly and 96.1+/-6.4% for MGly. The analytical performance showed good accuracy, suitable precision (<12.0%), low detection limits (15 ng L(-1) for Gly and 25 ng L(-1) for MGly adducts) and excellent linear dynamic ranges (r2>0.99) from 0.1 to 120.0 microg L(-1). By using the standard addition method, the application of the present method to tap and swimming-pool water, beer, yeast cells suspension and urine samples allowed very good performance at the trace level. The proposed methodology proved to be a feasible alternative for routine quality control analysis, showing to be easy to implement, reliable, sensitive and with a low sample volume requirement to monitor Gly and MGly in environmental and biological matrices.

A facile photoelectrochemical sensor for high sensitive ROS and AA detection based on graphitic carbon nitride nanosheets.

PubMed

Motaghed Mazhabi, Robabeh; Ge, Liqin; Jiang, Hui; Wang, Xuemei

2018-06-01

Photoactive material is one of the main challenges for fabrication of sensitive and selective photoelectrochemical (PEC) sensor. Herein, a facile PEC sensor is constructed using graphitic carbon nitride nanosheets (g-C 3 N 4 NSs) coated on the surface of ITO electrode, where electron donor properties of potassium ferrocyanide and ascorbic acid is utilized for the tracing of hydrogen peroxide (H 2 O 2 ), hypochlorite (ClO - ), and ascorbic acid (AA). Our designed PEC sensor exhibits a good linear range to H 2 O 2 concentrations from 12.5 to 875 µM in pH = 7.4 and 2.5-400 µM in pH = 10, while that for AA is in the range from 0.25 to 100 µM in pH = 7.4, and with the same pH for ClO - concentrations in the range from 0.5 to 19 × 10 -3 % (V/V) in a bleach sample. Owing to the good responses towards the traces of H 2 O 2 , AA, and ClO - , our designed system may be used as H 2 O 2, ClO - , and AA sensor for outdoor applications with high specificity, long-time stability and good reproducibility. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

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.

A carbon dot-based "off-on" fluorescent probe for highly selective and sensitive detection of phytic acid.

PubMed

Gao, Zhao; Wang, Libing; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

2015-08-15

We herein report a facile, one-step pyrolysis synthesis of photoluminescent carbon dots (CDs) using citric acid as the carbon source and lysine as the surface passivation reagent. The as-prepared CDs show narrow size distribution, excellent blue fluorescence and good photo-stability and water dispersivity. The fluorescence of the CDs was found to be effectively quenched by ferric (Fe(III)) ions with high selectivity via a photo-induced electron transfer (PET) process. Upon addition of phytic acid (PA) to the CDs/Fe(III) complex dispersion, the fluorescence of the CDs was significantly recovered, arising from the release of Fe(III) ions from the CDs/Fe(III) complex because PA has a higher affinity for Fe(III) ions compared to CDs. Furthermore, we developed an "off-on" fluorescence assay method for the detection of phytic acid using CDs/Fe(III) as a fluorescent probe. This probe enables the selective detection of PA with a linear range of 0.68-18.69 μM and a limit of detection (signal-to-noise ratio is 3) of 0.36 μM. The assay method demonstrates high selectivity, repeatability, stability and recovery ratio in the detection of the standard and real PA samples. We believe that the facile operation, low-cost, high sensitivity and selectivity render this CD-based "off-on" fluorescent probe an ideal sensing platform for the detection of PA. Copyright © 2015 Elsevier B.V. All rights reserved.

Highly sensitive ;turn-on; fluorescent chemical sensor for trace analysis of Cr3 + using electro-synthesized poly(N-(9-fluorenylmethoxycarbonyl)-L-histidine)

NASA Astrophysics Data System (ADS)

Zhang, Hui; Zhang, Ge; Xu, Jingkun; Wen, Yangping; Ming, Shouli; Zhang, Jie; Ding, Wanchuan

2018-02-01

Trivalent chromium (Cr3 +) can cause severely environment pollution, declining quality of edible agro-products in plants and animals, and human diseases. Poly(N-(9-fluorenylmethoxycarbonyl)-L-histidine) (PFLH) synthesized by the direct electro-polymerization of its corresponding commercially available monomer in both boron trifluoride diethyl etherate and dichloromethane mixed system. The ;turn-on; type fluorescent sensor based on PFLH displayed high sensitivity and selectivity for Cr3 + detecting. The structure of PFLH was rationally proved by 1H NMR spectra, FT-IR spectra, quantum chemical calculations, and its optical properties were characterized. The electro-synthesized PFLH exhibited a ;turn-on; fluorescent response towards Cr3 +, which was employed as a sensing platform for the ;turn-on; fluorescent analysis of Cr3 + in a wide linear range from 5.1 nM to 25 μM with a low limit of detection as low as 1.7 nM. The possible mechanism of fluorescent ;turn-on; sensor based on PFLH for Cr3 + was proposed. The sensor displayed high sensitivity, good selectivity, satisfactory practicability, suggesting that PFLH has potential fluorescent application for ;turn-on; sensing Cr3 + in agricultural environments and edible agro-products of plants and animals.

Detecting Liquefied Petroleum Gas (LPG) at Room Temperature Using ZnSnO3/ZnO Nanowire Piezo-Nanogenerator as Self-Powered Gas Sensor.

PubMed

Fu, Yongming; Nie, Yuxin; Zhao, Yayu; Wang, Penglei; Xing, Lili; Zhang, Yan; Xue, Xinyu

2015-05-20

High sensitivity, selectivity, and reliability have been achieved from ZnSnO3/ZnO nanowire (NW) piezo-nanogenerator (NG) as self-powered gas sensor (SPGS) for detecting liquefied petroleum gas (LPG) at room temperature (RT). After being exposed to 8000 ppm LPG, the output piezo-voltage of ZnSnO3/ZnO NW SPGS under compressive deformation is 0.089 V, much smaller than that in air ambience (0.533 V). The sensitivity of the SPGS against 8000 ppm LPG is up to 83.23, and the low limit of detection is 600 ppm. The SPGS has lower sensitivity against H2S, H2, ethanol, methanol and saturated water vapor than LPG, indicating good selectivity for detecting LPG. After two months, the decline of the sensing performance is less than 6%. Such piezo-LPG sensing at RT can be ascribed to the new piezo-surface coupling effect of ZnSnO3/ZnO nanocomposites. The practical application of the device driven by human motion has also been simply demonstrated. This work provides a novel approach to fabricate RT-LPG sensors and promotes the development of self-powered sensing system.

Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles.

PubMed

Gholivand, Mohammad-Bagher; Jalalvand, Ali R; Goicoechea, Hector C

2014-07-01

For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1-30.0 μM and 30.0-330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. Copyright © 2014. Published by Elsevier B.V.

Selective sensing of submicromolar iron(III) with 3,3‧,5,5‧-tetramethylbenzidine as a chromogenic probe

NASA Astrophysics Data System (ADS)

Zhang, Lufeng; Du, Jianxiu

2016-04-01

The development of highly selective and sensitive method for iron(III) detection is of great importance both from human health as well as environmental point of view. We herein reported a simple, selective and sensitive colorimetric method for the detection of Fe(III) at submicromolar level with 3,3,‧5,5‧-tetramethylbenzidine (TMB) as a chromogenic probe. It was observed that Fe(III) could directly oxidize TMB to form a blue solution without adding any extra oxidants. The reaction has a stoichiometric ratio of 1:1 (Fe(III)/TMB) as determined by a molar ratio method. The resultant color change can be perceived by the naked eye or monitored the absorbance change at 652 nm. The method allowed the measurement of Fe(III) in the range 1.0 × 10- 7-1.5 × 10- 4 mol L- 1 with a detection limit of 5.5 × 10- 8 mol L- 1. The relative standard deviation was 0.9% for eleven replicate measurements of 2.5 × 10- 5 mol L- 1 Fe(III) solution. The chemistry showed high selectivity for Fe(III) in contrast to other common cation ions. The practically of the method was evaluated by the determination of Fe in milk samples; good consistency was obtained between the results of this method and atomic absorption spectrophotometry as indicated by statistical analysis.

Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

1999-01-01

As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

A Water-Soluble Fluorescent Probe for SO2 Derivatives in Aqueous Solution and Serum Based on Phenanthroimidazole Dye.

PubMed

Zhou, Yang; Wang, Ying; Xiao, Shuzhang; He, Xiafeng; Zhang, Nuonuo; Li, Dejiang; Zheng, Kaibo

2017-05-01

A water-soluble fluorescent SO 2 derivatives probe PI-SO 2 based on a phenanthroimidazole dye, and a sensitive SO 2 recognition site, aldehyde was constructed. The probe PI-SO 2 exhibits desirable properties such as high sensitivity, high selectivity and good water-solubility. Significantly, we have demonstrated that the probe PI-SO 2 is suitable for rapidly fluorescence detecting of SO 2 derivatives in aqueous solution and serum. The application of the novel probe PI-SO 2 proved that it was not only a useful tool for the detection of SO 2 derivatives in vitro, but also a potential assay for investigating the effects of SO 2 derivatives, and demonstrating its value in practical applicationin of complex biological samples.

Synthesis and evaluation of 7-substituted 4-aminoquinoline analogues for antimalarial activity.

PubMed

Hwang, Jong Yeon; Kawasuji, Takashi; Lowes, David J; Clark, Julie A; Connelly, Michele C; Zhu, Fangyi; Guiguemde, W Armand; Sigal, Martina S; Wilson, Emily B; Derisi, Joseph L; Guy, R Kiplin

2011-10-27

We previously reported that substituted 4-aminoquinolines with a phenyl ether substituent at the 7-position of the quinoline ring and the capability of intramolecular hydrogen bonding between the protonated amine on the side chain and a hydrogen bond acceptor on the amine's alkyl substituents exhibited potent antimalarial activity against the multidrug resistant strain P. falciparum W2. We employed a parallel synthetic method to generate diaryl ether, biaryl, and alkylaryl 4-aminoquinoline analogues in the background of a limited number of side chain variations that had previously afforded potent 4-aminoquinolines. All subsets were evaluated for their antimalarial activity against the chloroquine-sensitive strain 3D7 and the chloroquine-resistant K1 strain as well as for cytotoxicity against mammalian cell lines. While all three arrays showed good antimalarial activity, only the biaryl-containing subset showed consistently good potency against the drug-resistant K1 strain and good selectivity with regard to mammalian cytotoxicity. Overall, our data indicate that the biaryl-containing series contains promising candidates for further study.

Ability-performance relationships in education and employment settings: critical tests of the more-is-better and the good-enough hypotheses.

PubMed

Arneson, Justin J; Sackett, Paul R; Beatty, Adam S

2011-10-01

The nature of the relationship between ability and performance is of critical importance for admission decisions in the context of higher education and for personnel selection. Although previous research has supported the more-is-better hypothesis by documenting linearity of ability-performance relationships, such research has not been sensitive enough to detect deviations at the top ends of the score distributions. An alternative position receiving considerable attention is the good-enough hypothesis, which suggests that although higher levels of ability may result in better performance up to a threshold, above this threshold greater ability does not translate to better performance. In this study, the nature of the relationship between cognitive ability and performance was examined throughout the score range in four large-scale data sets. Monotonicity was maintained in all instances. Contrary to the good-enough hypothesis, the ability-performance relationship was commonly stronger at the top end of the score distribution than at the bottom end.

Label-Free Detection of Cardiac Troponin-I Using Carbon Nanofiber Based Nanoelectrode Arrays

NASA Technical Reports Server (NTRS)

Periyakaruppan, Adaikkappan; Koehne, Jessica Erin; Gandhiraman, Ram P.; Meyyappan, M.

2013-01-01

A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. A carbon nanofiber (CNF) multiplexed array has been fabricated with 9 sensing pads, each containing 40,000 carbon nanofibers as nanoelectrodes. Here, we report the use of vertically aligned CNF nanoelectrodes for the detection of cardiac Troponin-I for the early diagnosis of myocardial infarction. Antibody, antitroponin, probe immobilization and subsequent binding to human cardiac troponin-I were characterized using electrochemical impedance spectroscopy and cyclic voltammetry techniques. Each step of the modification process resulted in changes in electrical capacitance or resistance to charge transfer due to the changes at the electrode surface upon antibody immobilization and binding to the specific antigen. This sensor demonstrates high sensitivity, down to 0.2 ng/mL, and good selectivity making this platform a good candidate for early stage diagnosis of myocardial infarction.

Rationality alters the rank between peer punishment and social exclusion

NASA Astrophysics Data System (ADS)

Sui, Xiukai; Wu, Bin; Wang, Long

2018-02-01

Peer punishment and social exclusion are two ways to punish free-riders. Previous work usually focuses on how their presence, either peer punishment or social exclusion, shapes the evolution of cooperation. Little attention has been given to which of these two strategies is favored by natural selection when they are both present. Here we investigate how rationality alters the ranking of these two strategies. Under weak rationality, for compulsory public goods games, peer punishment has an evolutionary advantage over social exclusion if the efficiency of punishment or the cost of exclusion is high. Furthermore, this rank is preserved for voluntary public goods games where loners are involved. Under strong rationality, however, peer punishment cannot prevail over social exclusion for both compulsory and voluntary public goods games. This indicates that rationality greatly alters the rank between peer punishment and social exclusion. Moreover, we find that this ranking is sensitive to the rationality. Our work thus gives an insight into how different types of punishment evolve.

A sensitive, selective and rapid determination of lead(II) ions in real-life samples using an electrochemically reduced graphene oxide-graphite reinforced carbon electrode.

PubMed

Hamsawahini, Kunashegaran; Sathishkumar, Palanivel; Ahamad, Rahmalan; Yusoff, Abdull Rahim Mohd

2015-11-01

In this study, a sensitive and cost-effective electrochemically reduced graphene oxide (ErGO) on graphite reinforced carbon (GRC) was developed for the detection of lead (Pb(II)) ions present in the real-life samples. A film of graphene oxide (GO) was drop-casted on GRC and their electrochemical properties were investigated using cyclic voltammetry (CV), amperometry and square wave voltammetry (SWV). Factors influencing the detection of Pb(II) ions, such as grades of GRC, constant applied cathodic potential (CACP), concentration of hydrochloric acid and drop-casting drying time were optimised. GO is irreversibly reduced in the range of -0.7 V to -1.6 V vs Ag/AgCl (3 M) in acidic condition. The results showed that the reduction behaviour of GO contributed to the high sensitivity of Pb(II) ions detection even at nanomolar level. The ErGO-GRC showed the detection limit of 0.5 nM and linear range of 3-15 nM in HCl (1 M). The developed electrode has potential to be a good candidate for the determination of Pb(II) ions in different aqueous system. The proposed method gives a good recovery rate of Pb(II) ions in real-life water samples such as tap water and river water. Copyright © 2015 Elsevier B.V. All rights reserved.

[A ten-year clinical study of cracked teeth restored with glass ceramic crowns].

PubMed

Luo, X P; Yuan, Y; Shi, Y J; Qian, D D

2016-10-09

Objective: To evaluate the clinic performance of high strength glass ceramic crowns for the painful cracked teeth during a 10-year observation period. Methods: Forty-two posterior teeth from 36 patients were diagnosed as having a crack, biting painful and sensitivity to cold were selected in the Department of Prosthodontic, Institute and Hospital of Stomatology, Nanjing University Medical School. The lost-wax hot pressed glass ceramic crowns were bonded on the minimally invasive prepared teeth by modern adhesive technology. Patients were interviewed and went through clinic examination after one week, one month, and every six months. Results: The effectiveness of 42 glass ceramic crowns for cracked teeth was evaluated for a mean observation time over 10-year. At the first week, 29(81%) patients were free of pain, three still had sensitivity to cold and chewing pain, three still had sensitivity to cold, one had painful to cold and hot. After one month, two patients still had chewing pain, and one tooth needed endodontic treatment after six months. In 10 years, 2(5%) all ceramic crowns were broken, the other 40 restorations kept good clinical performances with a 10-year survival rate of 95%. Conclusions: The high strength glass ceramic crowns are very effective and successful in treating the cracked teeth and then keep the good mastication function and appearance.

An Enzyme-Induced Novel Biosensor for the Sensitive Electrochemical Determination of Isoniazid

PubMed Central

Chokkareddy, Rajasekhar; Bhajanthri, Natesh Kumar; Redhi, Gan G.

2017-01-01

In this present work, a glassy carbon electrode (GCE) was modified primarily with multiwalled carbon nanotubes (MWCNTs) and a composite of MWCNTs and titanium oxide nanoparticles (TiO2NPs). The enzyme horseradish peroxidase (HRP) was immobilized to enhance the sensing ability of GCE. The proposed biosensor was used for the sensitive determination of isoniazid (INZ) in various pharmaceutical samples. The electrochemical behaviour of the developed MWCNT-TiO2NPs-HRP-GCE biosensor was studied by using cyclic voltammetry (CV) and differential pulse voltammetric (DPV) techniques. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetry (TGA) and transmission electron microscopy (TEM) techniques were used to characterize the developed sensor. Phosphate buffer solution (PBS) with pH 7 was used as supporting electrolyte in the present investigation. The cyclic voltammetric results revealed that the increment of anodic peak currents for the enzyme-induced sensor was almost 8-fold greater than that of a bare GCE. The DPV technique exhibited good limit of detection and limit of quantification values, viz., 0.0335 μM and 0.1118 μM, respectively. Moreover, the developed sensor showed long-lasting stability and repeatability without any interferents. This strongly indicates that the fabricated sensor shows outstanding electrochemical performance towards INZ, with excellent selectivity and sensitivity. The developed sensor was successfully applied to pharmaceutical samples and gave good percentages of recoveries. PMID:28587260

A new fluorescent probe for colorimetric and ratiometric detection of sulfur dioxide derivatives in liver cancer cells

NASA Astrophysics Data System (ADS)

Li, Dong-Peng; Wang, Zhao-Yang; Cui, Jie; Wang, Xin; Miao, Jun-Ying; Zhao, Bao-Xiang

2017-03-01

A new ratiometric fluorescent probe was constructed with hemicyanine and 7-nitrobenzofurazan for detection of sulfur dioxide derivatives (HSO3-/SO32-). The ratiometric response mode could be attributed to the efficient FRET (Förster resonance energy transfer) platform. The probe exbihited some desirable properties including fast response (within 2 minutes), good selectivity and high sensitivity. Moreover, the probe could detect endogenous HSO3- in liver cancer cells rather than normal liver cells, implying the diagnosal potential of the probe.

Evaluating aquatic invertebrate vulnerability to insecticides based on intrinsic sensitivity, biological traits, and toxic mode of action.

PubMed

Rico, Andreu; Van den Brink, Paul J

2015-08-01

In the present study, the authors evaluated the vulnerability of aquatic invertebrates to insecticides based on their intrinsic sensitivity and their population-level recovery potential. The relative sensitivity of invertebrates to 5 different classes of insecticides was calculated at the genus, family, and order levels using the acute toxicity data available in the US Environmental Protection Agency ECOTOX database. Biological trait information was linked to the calculated relative sensitivity to evaluate correlations between traits and sensitivity and to calculate a vulnerability index, which combines intrinsic sensitivity and traits describing the recovery potential of populations partially exposed to insecticides (e.g., voltinism, flying strength, occurrence in drift). The analysis shows that the relative sensitivity of arthropods depends on the insecticide mode of action. Traits such as degree of sclerotization, size, and respiration type showed good correlation to sensitivity and can be used to make predictions for invertebrate taxa without a priori sensitivity knowledge. The vulnerability analysis revealed that some of the Ephemeroptera, Plecoptera, and Trichoptera taxa were vulnerable to all insecticide classes and indicated that particular gastropod and bivalve species were potentially vulnerable. Microcrustaceans (e.g., daphnids, copepods) showed low potential vulnerability, particularly in lentic ecosystems. The methods described in the present study can be used for the selection of focal species to be included as part of ecological scenarios and higher tier risk assessments. © 2015 SETAC.

Calibration test of the temperature and strain sensitivity coefficient in regional reference grating method

NASA Astrophysics Data System (ADS)

Wu, Jing; Huang, Junbing; Wu, Hanping; Gu, Hongcan; Tang, Bo

2014-12-01

In order to verify the validity of the regional reference grating method in solve the strain/temperature cross sensitive problem in the actual ship structural health monitoring system, and to meet the requirements of engineering, for the sensitivity coefficients of regional reference grating method, national standard measurement equipment is used to calibrate the temperature sensitivity coefficient of selected FBG temperature sensor and strain sensitivity coefficient of FBG strain sensor in this modal. And the thermal expansion sensitivity coefficient of the steel for ships is calibrated with water bath method. The calibration results show that the temperature sensitivity coefficient of FBG temperature sensor is 28.16pm/°C within -10~30°C, and its linearity is greater than 0.999, the strain sensitivity coefficient of FBG strain sensor is 1.32pm/μɛ within -2900~2900μɛ whose linearity is almost to 1, the thermal expansion sensitivity coefficient of the steel for ships is 23.438pm/°C within 30~90°C, and its linearity is greater than 0.998. Finally, the calibration parameters are used in the actual ship structure health monitoring system for temperature compensation. The results show that the effect of temperature compensation is good, and the calibration parameters meet the engineering requirements, which provide an important reference for fiber Bragg grating sensor is widely used in engineering.

Aflatoxin B1 Detection Using a Highly-Sensitive Molecularly-Imprinted Electrochemical Sensor Based on an Electropolymerized Metal Organic Framework

PubMed Central

Jiang, Mengjuan; Braiek, Mohamed; Florea, Anca; Chrouda, Amani; Farre, Carole; Bonhomme, Anne; Bessueille, Francois; Vocanson, Francis; Zhang, Aidong; Jaffrezic-Renault, Nicole

2015-01-01

A sensitive electrochemical molecularly-imprinted sensor was developed for the detection of aflatoxin B1 (AFB1), by electropolymerization of p-aminothiophenol-functionalized gold nanoparticles in the presence of AFB1 as a template molecule. The extraction of the template leads to the formation of cavities that are able to specifically recognize and bind AFB1 through π-π interactions between AFB1 molecules and aniline moities. The performance of the developed sensor for the detection of AFB1 was investigated by linear sweep voltammetry using a hexacyanoferrate/hexacyanoferrite solution as a redox probe, the electron transfer rate increasing when the concentration of AFB1 increases, due to a p-doping effect. The molecularly-imprinted sensor exhibits a broad linear range, between 3.2 fM and 3.2 µM, and a quantification limit of 3 fM. Compared to the non-imprinted sensor, the imprinting factor was found to be 10. Selectivity studies were also performed towards the binding of other aflatoxins and ochratoxin A, proving good selectivity. PMID:26371042

Grafting polyethylenimine with quinoline derivatives for targeted imaging of intracellular Zn(2+) and logic gate operations.

PubMed

Pan, Yi; Shi, Yupeng; Chen, Junying; Wong, Chap-Mo; Zhang, Heng; Li, Mei-Jin; Li, Cheuk-Wing; Yi, Changqing

2016-12-01

In this study, a highly sensitive and selective fluorescent Zn(2+) probe which exhibited excellent biocompatibility, water solubility, and cell-membrane permeability, was facilely synthesized in a single step by grafting polyethyleneimine (PEI) with quinoline derivatives. The primary amino groups in the branched PEI can increase water solubility and cell permeability of the probe PEIQ, while quinoline derivatives can specifically recognize Zn(2+) and reduce the potential cytotoxicity of PEI. Basing on fluorescence off-on mechanism, PEIQ demonstrated excellent sensing capability towards Zn(2+) in absolute aqueous solution, where a high sensitivity with a detection limit as low as 38.1nM, and a high selectivity over competing metal ions and potential interfering amino acids, were achieved. Inspired by these results, elementary logic operations (YES, NOT and INHIBIT) have been constructed by employing PEIQ as the gate while Zn(2+) and EDTA as chemical inputs. Together with the low cytotoxicity and good cell-permeability, the practical application of PEIQ in living cell imaging was satisfactorily demonstrated, emphasizing its wide application in fundamental biology research. Copyright © 2016. Published by Elsevier B.V.

Colorimetric determination of Al(III) based on the aggregation of gold nanoparticles functionalized with novel 4-benzoyl pyrazolone derivative

NASA Astrophysics Data System (ADS)

Abubaker, Mariam; Ngah, Che Wan Zanariah Che Wan; Ahmad, Musa; Kuswandi, Bambang

2018-06-01

A sensitive and selective colorimetric method has been developed for detection of Al3+ ion using 4-benzoyl pyrazolone-functionalized gold nanoparticles (BMPBP-AuNPs) as novel colorimetric probes. The BMPBP-AuNPs were characterized by UV-visible spectrometry and transmission electron microscopy (TEM). It was found that the addition of the Al3+ ions led to a rapid aggregation of the BMPBP-AuNPs, which changed the color of the mixture from red to blue. Furthermore, there was a shift in the characteristic surface plasmon resonance (SPR) peak from 524 to 650 nm of BMPBP-AuNPs, which confirmed that a good linear relation (R2 = 0.9935) was present between the absorption ratio of 524 and 650 nm. Also, the assay detected the Al3+ ion concentrations in the linear range 0-12 ppm with the detection limit is 0.05 ppm. Finally, the synthesized BMPBP-AuNPs were successfully used as a colorimetric sensor for the selective and sensitive detection of the Al3+ ions in water samples.

High selectivity of colorimetric detection of p-nitrophenol based on Ag nanoclusters

NASA Astrophysics Data System (ADS)

Qu, Fei; Chen, Ping; Zhu, Shuyun; You, Jinmao

2017-01-01

Ag nanoclusters (Ag NCs) templated by hyperbranched polyethyleneimine (PEI) with different terminal groups and molecular weights had been developed as a special optical sensor for detecting p-nitrophenol (p-NP). When adding p-NP into Ag NCs, an obvious color change from pale yellow to deep yellow could be observed by naked eyes, accompanying with an apparent red-shift of absorption peak, and the reason was attributed to the formation of oxygen anion of p-NP based on the transfer of H+ from p-NP to amine groups of PEI. The molecular weights of template would greatly affect the sensitivity of p-NP. Ag NCs capped by PEI terminated ethylenediamine (EDA) possessed better sensitivity than other Ag NCs, showing good linear range from 5 to 140 μM with the limit of detection as low as 1.28 μM. Most importantly, this present system displayed high selectivity toward p-NP even in the presence of other nitrophenols and nitrotoluenes. This reliable method had been successfully applied for the detection of p-NP in real water and soil samples.

Neural correlates of individual performance differences in resolving perceptual conflict.

PubMed

Labrenz, Franziska; Themann, Maria; Wascher, Edmund; Beste, Christian; Pfleiderer, Bettina

2012-01-01

Attentional mechanisms are a crucial prerequisite to organize behavior. Most situations may be characterized by a 'competition' between salient, but irrelevant stimuli and less salient, relevant stimuli. In such situations top-down and bottom-up mechanisms interact with each other. In the present fMRI study, we examined how interindividual differences in resolving situations of perceptual conflict are reflected in brain networks mediating attentional selection. Doing so, we employed a change detection task in which subjects had to detect luminance changes in the presence and absence of competing distractors. The results show that good performers presented increased activation in the orbitofrontal cortex (BA 11), anterior cingulate (BA 25), inferior parietal lobule (BA 40) and visual areas V2 and V3 but decreased activation in BA 39. This suggests that areas mediating top-down attentional control are stronger activated in this group. Increased activity in visual areas reflects distinct neuronal enhancement relating to selective attentional mechanisms in order to solve the perceptual conflict. Opposed to good performers, brain areas activated by poor performers comprised the left inferior parietal lobule (BA 39) and fronto-parietal and visual regions were continuously deactivated, suggesting that poor performers perceive stronger conflict than good performers. Moreover, the suppression of neural activation in visual areas might indicate a strategy of poor performers to inhibit the processing of the irrelevant non-target feature. These results indicate that high sensitivity in perceptual areas and increased attentional control led to less conflict in stimulus processing and consequently to higher performance in competitive attentional selection.

SVM-based automatic diagnosis method for keratoconus

NASA Astrophysics Data System (ADS)

Gao, Yuhong; Wu, Qiang; Li, Jing; Sun, Jiande; Wan, Wenbo

2017-06-01

Keratoconus is a progressive cornea disease that can lead to serious myopia and astigmatism, or even to corneal transplantation, if it becomes worse. The early detection of keratoconus is extremely important to know and control its condition. In this paper, we propose an automatic diagnosis algorithm for keratoconus to discriminate the normal eyes and keratoconus ones. We select the parameters obtained by Oculyzer as the feature of cornea, which characterize the cornea both directly and indirectly. In our experiment, 289 normal cases and 128 keratoconus cases are divided into training and test sets respectively. Far better than other kernels, the linear kernel of SVM has sensitivity of 94.94% and specificity of 97.87% with all the parameters training in the model. In single parameter experiment of linear kernel, elevation with 92.03% sensitivity and 98.61% specificity and thickness with 97.28% sensitivity and 97.82% specificity showed their good classification abilities. Combining elevation and thickness of the cornea, the proposed method can reach 97.43% sensitivity and 99.19% specificity. The experiments demonstrate that the proposed automatic diagnosis method is feasible and reliable.

Label-free electrochemical aptasensor constructed by layer-by-layer technology for sensitive and selective detection of cancer cells.

PubMed

Wang, Tianshu; Liu, Jiyang; Gu, Xiaoxiao; Li, Dan; Wang, Jin; Wang, Erkang

2015-07-02

Here, a cytosensor was constructed with ferrocene-appended poly(allylamine hydrochloride) (Fc-PAH) functionalized graphene (Fc-PAH-G), poly(sodium-p-styrenesulfonate) (PSS) and aptamer (AS1411) by layer-by-layer assembly technology. The hybrid nanocomposite Fc-PAH-G not only brings probes on the electrode and also promotes electron transfer between the probes and the substrate electrode. Meanwhile, LBL technology provides more effective probes to enhance amplified signal for improving the sensitivity of the detection. While AS1411 forming G-quardruplex structure and binding cancer cells, the current response of the sensing electrode decreased due to the insulating properties of cellular membrane. Differential pulse voltammetry (DPV) was performed to investigate the electrochemical detection of HeLa cells attributing to its sensitivity of the current signal change. The as-prepared aptasensor showed a high sensitivity and good stability, a widely detection range from 10 to 10(6) cells/mL with a detection limit as low as 10 cells/mL for the detection of cancer cells. Copyright © 2015. Published by Elsevier B.V.

A biolayer interferometry-based enzyme-linked aptamer sorbent assay for real-time and highly sensitive detection of PDGF-BB.

PubMed

Gao, Shunxiang; Zheng, Xin; Wu, Jihong

2018-04-15

Accurate, fast and sensitive detection of disease-specific protein biomarkers, especially in blood, urine, or other bodily fluids, is an important approach to achieve early disease diagnosis. Platelet-derived growth factor-BB (PDGF-BB), a widely used biomarker, is involved in a substantial number of serious diseases, such as hepatic fibrosis, atherosclerosis, age-related macular degeneration and diabetic eye disease and is often over-expressed in human malignant tumors. Therefore, the development of sensitive and specific detection methods for PDGF-BB is of great importance for the early diagnosis of disease and assessments of patient recovery. In the current study, a biolayer interferometry-based enzyme-linked aptamer sorbent assay (BLI-ELASA) was successfully established for rapid (20-25min), high-throughput (8 or 16 samples) and real-time monitoring of PDGF-BB in clinical samples. The method exhibited a broad detection range from 0.5 to 1000ng/mL of PDGF-BB (good linear range from 0.5 to 10ng/mL), with a low detection limit of 0.08ng/mL. Moreover, BLI-ELASA was applied to the detection of PDGF-BB in spiked serum and urine samples and showed a high degree of selectivity for PDGF-BB, good reproducibility, and stability. We believe that the methodology in this work can be easily adapted to detect other biomolecules in clinical samples, including viruses, pathogens and toxins, in a rapid, sensitive, high-throughput and real-time manner. Copyright © 2017 Elsevier B.V. All rights reserved.

Saturated fatty acid determination method using paired ion electrospray ionization mass spectrometry coupled with capillary electrophoresis.

PubMed

Lee, Ji-Hyun; Kim, Su-Jin; Lee, Sul; Rhee, Jin-Kyu; Lee, Soo Young; Na, Yun-Cheol

2017-09-01

A sensitive and selective capillary electrophoresis-mass spectrometry (CE-MS) method for determination of saturated fatty acids (FAs) was developed by using dicationic ion-pairing reagents forming singly charged complexes with anionic FAs. For negative ESI detection, 21 anionic FAs at pH 10 were separated using ammonium formate buffer containing 40% acetonitrile modifier in normal polarity mode in CE by optimizing various parameters. This method showed good separation efficiency, but the sensitivity of the method to short-chain fatty acids was quite low, causing acetic and propionic acids to be undetectable even at 100 mgL -1 in negative ESI-MS detection. Out of the four dicationic ion-pairing reagents tested, N,N'-dibutyl 1,1'-pentylenedipyrrolidium infused through a sheath-liquid ion source during CE separation was the best reagent regarding improved sensitivity and favorably complexed with anionic FAs for detection in positive ion ESI-MS. The monovalent complex showed improved ionization efficiency, providing the limits of detection (LODs) for 15 FAs ranging from 0.13 to 2.88 μg/mL and good linearity (R 2  > 0.99) up to 150 μg/mL. Compared to the negative detection results, the effect was remarkable for the detection of short- and medium-chain fatty acids. The optimized CE-paired ion electrospray (PIESI)-MS method was utilized for the determination of FAs in cheese and coffee with simple pretreatment. This method may be extended for sensitive analysis of unsaturated fatty acids. Copyright © 2017 Elsevier B.V. All rights reserved.

Sensitive Detection of Neonicotinoid Insecticides and Other Selected Pesticides in Pollen and Nectar Using Nanoflow Liquid Chromatography Orbitrap Tandem Mass Spectrometry.

PubMed

Moreno-González, David; Alcántara-Durán, Jaime; Gilbert-López, Bienvenida; Beneito-Cambra, Miriam; Cutillas, Víctor M; Rajski, Łukasz; Molina-Díaz, Antonio; García-Reyes, Juan F

2018-03-01

In this work, a new method based on nanoflow LC with high-resolution MS was developed for the determination of eight pesticides in pollen and nectar samples, including neonicotinoid insecticides and other selected pesticides commonly found in bees and beeswax. Detection was undertaken with a hybrid quadrupole-Orbitrap mass spectrometer (Q Exactive™) equipped with a commercial nanospray ion source. The extraction of pesticides from pollen samples was performed by a modified micro-QuEChERS method scaled down to Eppendorf tubes, whereas nectar samples were simply diluted with a water-methanol (95 + 5, v/v) solution. Good linearity (>0.999 in all cases) was obtained between 0.05 and 500 µg/kg and between 0.04 and 400 µg/kg for pollen and nectar, respectively. Recovery rates in pollen ranged from 85 to 97%, with RSDs <12%. Matrix effect was evaluated and showed negligible effects for all studied pesticides. The lowest concentration levels tested and validated were 0.5 and 0.4 µg/kg for pollen and nectar matrixes, respectively. In addition, selected incurred samples were studied, obtaining several positive findings in pollen and nectar samples, demonstrating the sensitivity and applicability of the proposed method.

A selective and sensitive optical sensor for dissolved ammonia detection via agglomeration of fluorescent Ag nanoclusters and temperature gradient headspace single drop microextraction.

PubMed

Dong, Jiang Xue; Gao, Zhong Feng; Zhang, Ying; Li, Bang Lin; Li, Nian Bing; Luo, Hong Qun

2017-05-15

In this paper, a simple sensor platform is presented for highly selective and sensitive detection of dissolved ammonia in aqueous solutions without pretreatment based on temperature gradient headspace single drop microextraction (HS-SDME) technique, and fluorescence and UV-vis spectrophotometry are utilized with the Ag nanoclusters (Ag NCs) functioned by citrate and glutathione as the probe. The sensing mechanism is based on the volatility of ammonia gas and the active response of Ag NCs to pH change caused by the introduction of ammonia. High pH can make the Ag NCs agglomerate and lead to the obvious decrease of fluorescence intensity and absorbance of Ag NCs solution. Moreover, the presented method exhibits a remarkably high selectivity toward dissolved ammonia over most of inorganic ions and amino acid, and shows a good linear range of 10-350μM (0.14-4.9mgNL -1 ) with a low detection limit of 336nM (4.70μgNL -1 ) at a signal-to-noise ratio of 3. In addition, the practical applications of the sensor have been successfully demonstrated by detecting dissolved ammonia in real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

One-step synthesis of fluorescent carbon dots for sensitive and selective detection of hyperin.

PubMed

Liu, Lizhen; Mi, Zhi; Hu, Qin; Li, Caiqing; Li, Xiaohua; Feng, Feng

2018-08-15

In this article, we presented a new rapid, sensitive and selective method for the determination of hyperin (Hyp) based on the fluorescence quenching of fluorescent carbon dots (CDs). The CDs were prepared by simply mixing an aqueous solution of citric acid with diphosphorus pentoxide. This one-step synthetic route is fast and simple with neither high temperature nor complicated synthesis steps is involved. When Hyp was added to CDs solution, the fluorescence intensity of the CDs significantly decreased. The CDs display high selectivity for Hyp over many potentially interfering substances. Under the optimized conditions, a good linear relationship between the fluorescence intensity ratio F o /F and the concentration of Hyp is obtained in a range of 0.22-55 µM with a detection limit (S/N = 3) of 78.3 nM. The method was successfully applied for the determination of Hyp in fufangmuji granules and human serum samples with recoveries in a range of 93.3-107.0%. This paper highlights the usefulness of CDs as an effective fluorescence probe for the Hyp detection due to its easy preparation, low-cost, excellent photostability, favorable biocompatibility and low cytotoxicity. Copyright © 2018 Elsevier B.V. All rights reserved.

A highly selective electrochemical sensor based on molecularly imprinted polypyrrole-modified gold electrode for the determination of glyphosate in cucumber and tap water.

PubMed

Zhang, Chao; She, Yongxin; Li, Tengfei; Zhao, Fengnian; Jin, Maojun; Guo, Yirong; Zheng, Lufei; Wang, Shanshan; Jin, Fen; Shao, Hua; Liu, Haijin; Wang, Jing

2017-12-01

An electrochemical sensor based on molecularly imprinted polypyrrole (MIPPy) was developed for selective and sensitive detection of the herbicide glyphosate (Gly) in cucumber and tap water samples. The sensor was prepared via synthesis of molecularly imprinted polymers on a gold electrode in the presence of Gly as the template molecule and pyrrole as the functional monomer by cyclic voltammetry (CV). The sensor preparation conditions including the ratio of template to functional monomers, number of CV cycles in the electropolymerization process, the method of template removal, incubation time, and pH were optimized. Under the optimal experimental conditions, the DPV peak currents of hexacyanoferrate/hexacyanoferrite changed linearly with Gly concentration in the range from 5 to 800 ng mL -1 , with a detection limit of 0.27 ng mL -1 (S/N = 3). The sensor was used to detect the concentration of Gly in cucumber and tap water samples, with recoveries ranging from 72.70 to 98.96%. The proposed sensor showed excellent selectivity, good stability and reversibility, and could detect the Gly in real samples rapidly and sensitively. Graphical abstract Schematic illustration of the experimental procedure to detect Gly using the MIPPy electrode.

Simultaneous determination of eight major steroids from Polyporus umbellatus by high-performance liquid chromatography coupled with mass spectrometry detections.

PubMed

Zhao, Ying-yong; Cheng, Xian-long; Zhang, Yongmin; Zhao, Ye; Lin, Rui-chao; Sun, Wen-ji

2010-02-01

Polyporus umbellatus is a widely used diuretic herbal medicine. In this study, a high-performance liquid chromatography coupled with atmospheric pressure chemical ionization-mass spectrometric detection (HPLC-APCI-MS) method was developed for qualitative and quantitative analysis of steroids, as well as for the quality control of Polyporus umbellatus. The selectivity, reproducibility and sensitivity were compared with HPLC with photodiode array detection and evaporative light scattering detection (ELSD). Selective ion monitoring in positive mode was used for qualitative and quantitative analysis of eight major components and beta-ecdysterone was used as the internal standard. Limits of detection and quantification fell in the ranges 7-21 and 18-63 ng/mL for the eight analytes with an injection of 10 microL samples, and all calibration curves showed good linear regression (r(2) > 0.9919) within the test range. The quantitative results demonstrated that samples from different localities showed different qualities. Advantages, in comparison with conventional HPLC-diode array detection and HPLC-ELSD, are that reliable identification of target compounds could be achieved by accurate mass measurements along with characteristic retention time, and the great enhancement in selectivity and sensitivity allows identification and quantification of low levels of constituents in complex Polyporus umbellatus matrixes. (c) 2009 John Wiley & Sons, Ltd.

Effects of the pyrethroid insecticide gamma-cyhalothrin on aquatic invertebrates in laboratory and outdoor microcosm tests.

PubMed

van Wijngaarden, René P A; Barber, Ian; Brock, Theo C M

2009-02-01

The sensitivity of a range of freshwater lentic invertebrates to gamma-cyhalothrin (GCH), a single enantiomer of the synthetic pyrethroid lambda-cyhalothrin, was assessed in single species laboratory tests and an outdoor multi-species ecosystem test. The most sensitive species in the laboratory single species tests with GCH was Chaoborus obscuripes (96 h EC(50): 3.8 ng/l). The species sensitivity distribution curve, based on the laboratory 96 h EC(50) acute toxicity data for eight species, gave a median HC(5) value for GCH of 2.12 ng/l. The NOEC(community) derived from the multi-species ecosystem test was 5 ng/l, and the insects Chaoborus sp. and Caenis sp. were identified as the most sensitive species. The results indicate that the median HC(5), based on eight species selected to include those known to be sensitive to pyrethroids, provided a good estimation of the NOEC(community) for GCH. Furthermore, the results for GCH indicated that the endpoints typically used in higher-tier risk assessments for pesticides in Europe (HC(5) and NOEC(community)) were consistent with expectations when compared to the equivalent endpoints for the racemate LCH.

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

PubMed Central

Crouch, C F

1995-01-01

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

Earthquake Damage Assessment over Port-au-Prince (Haiti) by Fusing Optical and SAR Data

NASA Astrophysics Data System (ADS)

Romaniello, V.; Piscini, A.; Bignami, C.; Anniballe, R.; Pierdicca, N.; Stramondo, S.

2016-08-01

This work proposes methodologies aiming at evaluating the sensitivity of optical and SAR change features obtained from satellite images with respect to the damage grade. The proposed methods are derived from the literature ([1], [2], [3], [4]) and the main novelty concerns the estimation of these change features at object scale.The test case is the Mw 7.0 earthquake that hit Haiti on January 12, 2010.The analysis of change detection indicators is based on ground truth information collected during a post- earthquake survey. We have generated the damage map of Port-au-Prince by considering a set of polygons extracted from the open source Open Street Map geo- database. The resulting damage map was calculated in terms of collapse ratio [5].We selected some features having a good sensitivity with damage at object scale [6]: the Normalised Difference Index, the Kullback-Libler Divergence, the Mutual Information and the Intensity Correlation Difference.The Naive Bayes and the Support Vector Machine classifiers were used to evaluate the goodness of these features. The classification results demonstrate that the simultaneous use of several change features from EO observations can improve the damage estimation at object scale.

A new analytical device incorporating a nitrogen doped lanthanum metal oxide with reduced graphene oxide sheets for paracetamol sensing.

PubMed

Ponnaiah, Sathish Kumar; Prakash, Periakaruppan; Vellaichamy, Balakumar

2018-06-01

The novel N-CeO 2 nanoparticles decorated on reduced graphene oxide (N-CeO 2 @rGO) composite has been synthesized by sonochemical method. The characterization of as prepared nanocomposite was intensely performed by UV-Vis, FT-IR, EDX, FE-SEM, HR-TEM, XRD, and TGA analysis. The synthesized nanomaterial was further investigated for its selective and sensitive sensing of paracetamol (PM) based on a N-CeO 2 @rGO modified glassy carbon electrode. A distinct and improved reversible redox peak of PM is obtained at N-CeO 2 @rGO nanocomposite compared to the electrodes modified with N-CeO 2 and rGO. It displays a very good performance with a wide linear range of 0.05-0.600 μM, a very low detection limit of 0.0098 μM (S/N = 3), a high sensitivity of 268 μA µM -1  cm -2 and short response time (<3 s). Also, the fabricated sensor shows a good sensibleness for the detection of PM in various tablet samples. Copyright © 2018 Elsevier B.V. All rights reserved.

A SERS biosensor with magnetic substrate CoFe2O4@Ag for sensitive detection of Hg2+

NASA Astrophysics Data System (ADS)

Yang, Xia; He, Yi; Wang, Xueling; Yuan, Ruo

2017-09-01

Mercuric ion (Hg2+) is one toxic metal ion existed in aquatic ecosystems which would seriously damage human central nervous system and other organs. So developing an approach to sensitively detect Hg2+ in our living environment is urgent and important. In this work, a novel surface enhancement Raman spectrum(SERS) sensor is fabricated for high selective and ultrasensitive detection of Hg2+ in aqueous solution, based on a stable thymine-Hg2+-thymine (T-Hg2+-T) structure and the π-π interaction between single-stranded DNA (ssDNA) and single walled carbon nanotubes (SWCNTs). Herein, SWCNTs act as Raman labels to produce characteristic Raman peaks which can be a beacon to quantitative detect Hg2+. In the presence of Hg2+, the ssDNA can capture Hg2+ forming T-Hg2+-T structure, which makes SWCNTs leave the hot spots of the SERS-based biosensor. With this design, the Raman intensity of SWCNTs decreased with the increasing concentration of Hg2+. At the same time, CoFe2O4@Ag as active SERS substrates can effectively enhance sensitivity and uniformity of the biosensor through aggregation by magnet. Under optimal conditions, this proposed biosensor can detect Hg2+ at a range from 1 pM to 100 nM with a detection limit of 0.84 pM. With the advantages of good sensitivity, selectivity, simplicity and rapidity, the biosensor is potentially suitable for monitoring of Hg2+ in environmental applications.

Beyond semantic accuracy: preschoolers evaluate a speaker's reasons.

PubMed

Koenig, Melissa A

2012-01-01

Children's sensitivity to the quality of epistemic reasons and their selective trust in the more reasonable of 2 informants was investigated in 2 experiments. Three-, 4-, and 5-year-old children (N = 90) were presented with speakers who stated different kinds of evidence for what they believed. Experiment 1 showed that children of all age groups appropriately judged looking, reliable testimony, and inference as better reasons for belief than pretense, guessing, and desiring. Experiment 2 showed that 3- and 4-year-old children preferred to seek and accept new information from a speaker who was previously judged to use the "best" way of thinking. The findings demonstrate that children distinguish certain good from bad reasons and prefer to learn from those who showcased good reasoning in the past. © 2012 The Author. Child Development © 2012 Society for Research in Child Development, Inc.

Crack Detection in Plates Using Coupled Rayleigh-Like Waves

NASA Astrophysics Data System (ADS)

Masserey, B.; Fromme, P.

2008-02-01

The use of coupled Rayleigh-like waves in aluminum plates with a view towards the non-destructive inspection of aircraft structures has been investigated experimentally and theoretically. Rayleigh-like waves transfer energy between both plate surfaces with a characteristic distance called the beatlength. A simple, analytical model and finite difference calculations are used to describe the reflection of Rayleigh-like waves at surface defects. Good agreement has been achieved with experimental results using either standard pulse-echo or laser interferometer measurements. The sensitivity for the detection and localization of small defects on both plate surfaces has been found to be very good. Selecting appropriate excitation frequency and position, a significant part of the energy of the Rayleigh-like wave can be transmitted past surface features, allowing the remote detection of defects in areas where access is restricted.

Effect of Encapsulation on Antimicrobial Activity of
Herbal Extracts with Lysozyme

PubMed Central

Matouskova, Petra; Bokrova, Jitka; Benesova, Pavla

2016-01-01

Summary Resistance of microorganisms to antibiotics has increased. The use of natural components with antimicrobial properties can be of great significance to reduce this problem. The presented work is focused on the study of the effect of encapsulation of selected plant and animal antimicrobial substances (herbs, spices, lysozyme and nisin) on their activity and stability. Antimicrobial components were packaged into liposomes and polysaccharide particles (alginate, chitosan and starch). Antimicrobial activity was tested against two Gram-positive (Bacillus subtilis and Micrococcus luteus) and two Gram-negative (Escherichia coli and Serratia marcescens) bacteria. Encapsulation was successful in all types of polysaccharide particles and liposomes. The prepared particles exhibited very good long-term stability, especially in aqueous conditions. Antimicrobial activity was retained in all types of particles. Liposomes with encapsulated herb and spice extracts exhibited very good inhibitory effect against all tested bacterial strains. Most of herbal extracts had very good antimicrobial effect against the tested Gram-negative bacterial strains, while Gram-positive bacteria were more sensitive to lysozyme particles. Thus, particles with co-encapsulated herbs and lysozyme are more active against different types of bacteria, and more stable and more effective during long-term storage. Particles with encapsulated mixture of selected plant extracts and lysozyme could be used as complex antimicrobial preparation with controlled release in the production of food and food supplements, pharmaceutical and cosmetic industries. PMID:27956862

Highly sensitive detection of quantal dopamine secretion from pheochromocytoma cells using neural microelectrode array electrodeposited with polypyrrole graphene.

PubMed

Wang, Li; Xu, Huiren; Song, Yilin; Luo, Jinping; Wei, Wenjing; Xu, Shengwei; Cai, Xinxia

2015-04-15

For the measurement of events of dopamine (DA) release as well as the coordinating neurotransmission in the nerve system, a neural microelectrode array (nMEA) electrodeposited directionally with polypyrrole graphene (PG) nanocomposites was fabricated. The deposited graphene significantly increased the surface area of working electrode, which led to the nMEA (with diameter of 20 μm) with excellent selectivity and sensitivity to DA. Furthermore, PG film modification exhibited low detection limit (4 nM, S/N = 3.21), high sensitivity, and good linearity in the presence of ascorbic acid (e.g., 13933.12 μA mM(-1) cm(-2) in the range of 0.8-10 μM). In particular, the nMEA combined with the patch-clamp system was used to detect quantized DA release from pheochromocytoma cells under 100 mM K(+) stimulation. The nMEA that integrates 60 microelectrodes is novel for detecting a large number of samples simultaneously, which has potential for neural communication research.

"Reactive" optical sensor for Hg2+ and its application in environmental aqueous media and biological systems.

PubMed

Chen, Zhi; Chen, Jiayun; Pan, Dong; Li, Hongwei; Yao, Yunhui; Lyu, Zu; Yang, Liting; Ma, Li-Jun

2017-03-01

A new rhodamine B-based "reactive" optical sensor (1) for Hg 2+ was synthesized. Sensor 1 shows a unique colorimetric and fluorescent "turn-on" selectivity to Hg 2+ over 14 other metal ions with a hypersensitivity (detection limits are 27.6 nM (5.5 ppb) and 6.9 nM (1.4 ppb), respectively) in neutral buffer solution. To test its applicability in the environment, sensor 1 was applied to quantify and visualize low levels of Hg 2+ in tap water and river water samples. The results indicate sensor 1 is a highly sensitive fluorescent sensor for Hg 2+ with a detection limit of 1.7 ppb in tap water and river water. Moreover, sensor 1 is a convenient visualizing sensor for low levels of Hg 2+ (0.1 ppm) in water environment (from colorless to light pink). In addition, sensor 1 shows good potential as a fluorescent visualizing sensor for Hg 2+ in fetal bovine serum and living 293T cells. The results indicate that sensor 1 shows good potential as a highly sensitive sensor for the detection of Hg 2+ in environmental and biological samples. Graphical Abstract A new rhodamine B-based "reactive" optical sensor (1) for Hg 2+ was synthesized. 1 shows a unique colorimetric and fluorescent "turn-on" selectivity to Hg 2+ over 14 other metal ions with a hypersensitivity in water environment. And it is a convenient visualizing probe for low levels of Hg 2+ in environment aqueous media, fetal bovine serum and living 293T cells.

Chasing passive galaxies in the early Universe: a critical analysis in CANDELS GOODS-South

NASA Astrophysics Data System (ADS)

Merlin, E.; Fontana, A.; Castellano, M.; Santini, P.; Torelli, M.; Boutsia, K.; Wang, T.; Grazian, A.; Pentericci, L.; Schreiber, C.; Ciesla, L.; McLure, R.; Derriere, S.; Dunlop, J. S.; Elbaz, D.

2018-01-01

We search for passive galaxies at z > 3 in the GOODS-South field, using different techniques based on photometric data, and paying attention to develop methods that are sensitive to objects that have become passive shortly before the epoch of observation. We use CANDELS HST catalogues, ultra-deep Ks data and new IRAC photometry, performing spectral energy distribution fitting using models with abruptly quenched star formation histories. We then single out galaxies which are best fitted by a passively evolving model, and having only low probability (<5 per cent) star-forming solutions. We verify the effects of including nebular lines emission, and we consider possible solutions at different redshifts. The number of selected sources dramatically depends on the models used in the spectral energy distribution (SED) fitting. Without including emission lines and with photometric redshifts fixed at the CANDELS estimate, we single out 30 candidates; the inclusion of nebular lines emission reduces the sample to 10 objects; allowing for solutions at different redshifts, only two galaxies survive as robust candidates. Most of the candidates are not far-infrared emitters, corroborating their association with passive galaxies. Our results translate into an upper limit in the number density of ∼0.173 arcmin2 above the detection limit. However, we conclude that the selection of passive galaxies at z > 3 is still subject to significant uncertainties, being sensitive to assumptions in the SED modelling adopted and to the relatively low S/N of the objects. By means of dedicated simulations, we show that JWST will greatly enhance the accuracy, allowing for a much more robust classification.

Ion-Pair Extractive Spectrophotometric Assay of Terbinafine Hydrochloride in Pharmaceuticals and Spiked Urine Using Bromocresol Purple

NASA Astrophysics Data System (ADS)

Salem Qarah, N. A.; Basavaiah, K.; Swamy, N.

2016-09-01

Two simple, rapid, selective, and sensitive methods were developed and validated for the determination of terbinafi ne hydrochloride (TBH) in pharmaceuticals and urine. The fi rst method (method A) is based on the formation of a yellow ion-pair complex of TBH and bromocresol purple (BCP), a sulfonephthalein dye, in Walpole buffer of pH 3.61, which was extracted into chloroform and investigated at 420 nm. For the second method (method B) the drug-dye ion-pair was broken in alkaline KOH medium, and the resulting free dye color was measured at 610 nm. All variables were studied to optimize the reaction conditions. The regression analysis of Beer's law plots showed good correlation in the concentration ranges of 1-10 and 0.1-2.0 μg/mL for method A and method B, respectively. Molar absorptivity values were 2.99 × 104, and 1.51×105 L/(mol × cm) for measurements by these methods. The methods were also validated for limits of detection (LOD) and quantifi cation (LOQ), intra-day and inter-day accuracy and precision, selectivity, robustness and ruggedness. The composition of the ion-pair (drug-dye) used in the method A was found to be 1:1 by both mole-ratio and Job's methods. The developed methods were applied to tablets, and the results were in good agreement with the label claim and those of the reference method. Because of its high sensitivity, method A was applied to spiked human urine with percent recoveries in the range 96.58-107.3 and a standard deviation <2%.

The G-BHQ synergistic effect: Improved double quenching molecular beacons based on guanine and Black Hole Quencher for sensitive simultaneous detection of two DNAs.

PubMed

Xiang, Dongshan; Li, Fengquan; Wu, Chenyi; Shi, Boan; Zhai, Kun

2017-11-01

We designed two double quenching molecular beacons (MBs) with simple structure based on guanine (G base) and Black Hole Quencher (BHQ), and developed a new analytical method for sensitive simultaneous detection of two DNAs by synchronous fluorescence analysis. In this analytical method, carboxyl fluorescein (FAM) and tetramethyl-6-carboxyrhodamine (TAMRA) were respectively selected as fluorophore of two MBs, Black Hole Quencher 1 (BHQ-1) and Black Hole Quencher 2 (BHQ-2) were respectively selected as organic quencher, and three continuous nucleotides with G base were connected to organic quencher (BHQ-1 and BHQ-2). In the presence of target DNAs, the two MBs hybridize with the corresponding target DNAs, the fluorophores are separated from organic quenchers and G bases, leading to recovery of fluorescence of FAM and TAMRA. Under a certain conditions, the fluorescence intensities of FAM and TAMRA all exhibited good linear dependence on their concentration of target DNAs (T1 and T2) in the range from 4 × 10 -10 to 4 × 10 -8 molL -1 (M). The detection limit (3σ, n = 13) of T1 was 3 × 10 -10 M and that of T2 was 2×10 -10 M, respectively. Compared with the existing analysis methods for multiplex DNA with MBs, this proposed method based on double quenching MBs is not only low fluorescence background, short analytical time and low detection cost, but also easy synthesis and good stability of MB probes. Copyright © 2017 Elsevier B.V. All rights reserved.

Epoxy matrix with triaromatic mesogenic unit in dielectric spectroscopy observation

NASA Astrophysics Data System (ADS)

Włodarska, Magdalena; Mossety-Leszczak, Beata; Bąk, Grzegorz W.; Kisiel, Maciej; Dłużniewski, Maciej; Okrasa, Lidia

2018-04-01

This paper describes the dielectric response of a selected liquid crystal epoxy monomer (plain and in curing systems) in a wide range of frequency and temperature. The dielectric spectroscopy, thanks to its sensitivity, is a very good tool for studying phase transitions, reaction progress, or material properties. This sensitivity is important in the case of liquid crystal epoxy resins, where properties of the final network depend on the choice of monomers, curing agents, curing conditions and post-curing treatment, or applying an external electric or magnetic field during the reaction. In most of the obtained cured products, the collected dielectric data show two relaxation processes. The α-process is related to a structural reorientation; it can usually be linked with the glass transition and the mechanical properties of the material. The β-process can be identified as a molecular motion process, probably associated with the carboxyl groups in the mesogen. A transient Maxwell-Wagner relaxation observed in one of the compositions after the initial curing is removed by post-curing treatment at elevated temperatures. Post-curing is therefore necessary for obtaining uniformly cured products in those cases. In the investigated systems, the choice of a curing agent can change the glass transition temperature by at least 70 °C. The obtained results are in a good agreement with an earlier study employing other techniques. Finally, we assess the influence of the direction of mesogen alignment on the dielectric properties of one selected system, where a global order was induced by applying an external magnetic field in the course of curing.

Rapid and selective extraction of multiple macrolide antibiotics in foodstuff samples based on magnetic molecularly imprinted polymers.

PubMed

Zhou, Yusun; Zhou, Tingting; Jin, Hua; Jing, Tao; Song, Bin; Zhou, Yikai; Mei, Surong; Lee, Yong-Ill

2015-05-01

Magnetic molecularly imprinted polymers (MMIPs) were prepared based on surface molecular imprinting using erythromycin (ERY) as template molecule and Fe3O4 nanoparticles as support substrate. The MMIPs possessed high adsorption capacity of 94.1 mg/g for ERY and the imprinting factor was 11.9 indicating good imprinted effect for ERY. Selective evaluation demonstrated favorable selectivity of MMIPs for multiple macrolide antibiotics (MACs). Using MMIPs as adsorptive material, a rapid and convenient magnetic solid-phase extraction (MSPE) procedure was established for simultaneous and selective separation of six MACs in pork, fish and shrimp samples, then the MACs was subjected to high-performance liquid chromatography-ultraviolet (HPLC-UV) analysis. At different fortified concentrations, the extraction recoveries could reach 89.1% and the relative standard deviations were lower than 12.4%. Chromatogram revealed the response signals of MACs in spiked samples were greatly enhanced and matrix interferences were effectively eliminated after treatment with MSPE. The proposed MSPE procedure coupled with HPLC-UV realized selective and sensitive determination of multiple MACs in foodstuff samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Highly sensitive glucose sensors based on enzyme-modified whole-graphene solution-gated transistors

NASA Astrophysics Data System (ADS)

Zhang, Meng; Liao, Caizhi; Mak, Chun Hin; You, Peng; Mak, Chee Leung; Yan, Feng

2015-02-01

Noninvasive glucose detections are convenient techniques for the diagnosis of diabetes mellitus, which require high performance glucose sensors. However, conventional electrochemical glucose sensors are not sensitive enough for these applications. Here, highly sensitive glucose sensors are successfully realized based on whole-graphene solution-gated transistors with the graphene gate electrodes modified with an enzyme glucose oxidase. The sensitivity of the devices is dramatically improved by co-modifying the graphene gates with Pt nanoparticles due to the enhanced electrocatalytic activity of the electrodes. The sensing mechanism is attributed to the reaction of H2O2 generated by the oxidation of glucose near the gate. The optimized glucose sensors show the detection limits down to 0.5 μM and good selectivity, which are sensitive enough for non-invasive glucose detections in body fluids. The devices show the transconductances two orders of magnitude higher than that of a conventional silicon field effect transistor, which is the main reason for their high sensitivity. Moreover, the devices can be conveniently fabricated with low cost. Therefore, the whole-graphene solution-gated transistors are a high-performance sensing platform for not only glucose detections but also many other types of biosensors that may find practical applications in the near future.

Highly sensitive glucose sensors based on enzyme-modified whole-graphene solution-gated transistors

PubMed Central

Zhang, Meng; Liao, Caizhi; Mak, Chun Hin; You, Peng; Mak, Chee Leung; Yan, Feng

2015-01-01

Noninvasive glucose detections are convenient techniques for the diagnosis of diabetes mellitus, which require high performance glucose sensors. However, conventional electrochemical glucose sensors are not sensitive enough for these applications. Here, highly sensitive glucose sensors are successfully realized based on whole-graphene solution-gated transistors with the graphene gate electrodes modified with an enzyme glucose oxidase. The sensitivity of the devices is dramatically improved by co-modifying the graphene gates with Pt nanoparticles due to the enhanced electrocatalytic activity of the electrodes. The sensing mechanism is attributed to the reaction of H2O2 generated by the oxidation of glucose near the gate. The optimized glucose sensors show the detection limits down to 0.5 μM and good selectivity, which are sensitive enough for non-invasive glucose detections in body fluids. The devices show the transconductances two orders of magnitude higher than that of a conventional silicon field effect transistor, which is the main reason for their high sensitivity. Moreover, the devices can be conveniently fabricated with low cost. Therefore, the whole-graphene solution-gated transistors are a high-performance sensing platform for not only glucose detections but also many other types of biosensors that may find practical applications in the near future. PMID:25655666

Resistance-associated point mutations in insecticide-insensitive acetylcholinesterase.

PubMed Central

Mutero, A; Pralavorio, M; Bride, J M; Fournier, D

1994-01-01

Extensive utilization of pesticides against insects provides us with a good model for studying the adaptation of a eukaryotic genome to a strong selective pressure. One mechanism of resistance is the alteration of acetylcholinesterase (EC 3.1.1.7), the molecular target for organophosphates and carbamates. Here, we report the sequence analysis of the Ace gene in several resistant field strains of Drosophila melanogaster. This analysis resulted in the identification of five point mutations associated with reduced sensitivities to insecticides. In some cases, several of these mutations were found to be combined in the same protein, leading to different resistance patterns. Our results suggest that recombination between resistant alleles preexisting in natural populations is a mechanism by which insects rapidly adapt to new selective pressures. Images PMID:8016090

A new fluorescent pH probe for imaging lysosomes in living cells.

PubMed

Lv, Hong-Shui; Huang, Shu-Ya; Xu, Yu; Dai, Xi; Miao, Jun-Ying; Zhao, Bao-Xiang

2014-01-15

A new rhodamine B-based pH fluorescent probe has been synthesized and characterized. The probe responds to acidic pH with short response time, high selectivity and sensitivity, and exhibits a more than 20-fold increase in fluorescence intensity within the pH range of 7.5-4.1 with the pKa value of 5.72, which is valuable to study acidic organelles in living cells. Also, it has been successfully applied to HeLa cells, for its low cytotoxicity, brilliant photostability, good membrane permeability and no 'alkalizing effect' on lysosomes. The results demonstrate that this probe is a lysosome-specific probe, which can selectively stain lysosomes and monitor lysosomal pH changes in living cells. Copyright © 2013 Elsevier Ltd. All rights reserved.

Simultaneous determination of three major lignans in rat plasma by LC-MS/MS and its application to a pharmacokinetic study after oral administration of Diphylleia sinensis extract.

PubMed

Zhao, Chengliang; Zhang, Nan; He, Weiyan; Li, Rui; Shi, Dan; Pang, Li; Dong, Ning; Xu, Hong; Ji, Honglei

2014-04-01

A sensitive and selective liquid chromatography tandem mass spectrometry was developed and validated for the simultaneous determination of three major lignans (podophyllotoxin, epipodophyllotoxin, and 4'-demethylpodophyllotoxin) in rat plasma using diphenhydramine as the internal standard. The analytes were detected using a triple quadrupole mass spectrometer that was equipped with an electrospray ionization source in the positive ion and selected reaction monitoring modes. The linearity of the calibration curve was good, with coefficients of determination (r(2) ) >0.9914 for all of the analytes. The developed method was successfully applied for the simultaneous determination of the three lignans in rat plasma following oral administration of Diphylleia sinensis extract to rats. Copyright © 2013 John Wiley & Sons, Ltd.

A rhodamine chromene-based turn-on fluorescence probe for selectively imaging Cu2+ in living cell

NASA Astrophysics Data System (ADS)

Liu, Wei-Yong; Li, Hai-Ying; Lv, Hong-Shui; Zhao, Bao-Xiang; Miao, Jun-Ying

We describe the development of a rhodamine chromene-based turn-on fluorescence probe to monitor the intracellular Cu2+ level in living cells. The new fluorescent probe with a chlorine group in chromene moiety exhibits good membrane-permeable property than previous reported because the predicted lipophilicity of present probe 4 is stronger than that of methoxyl substituted probe in our previous work (CLogP of 4: 8.313, CLogP of methoxyl substituted probe: 7.706), and a fluorescence response toward Cu2+ under physiological conditions with high sensitivity and selectivity, and facilitates naked-eye detection of Cu2+. The fluorescence intensity was remarkably increased upon the addition of Cu2+ within 1 or 2 min, while the other sixteen metal ions caused no significant effect.

Mixed C18 and C1 modification on an optical fiber for chromatographic sensing.

PubMed

Zhou, Leiji; Wang, Kemin; Zuo, Xinbing; Choi, Martin M F; Chen, Yunqing; Huang, Shasheng

2003-09-01

An optical fiber-chromatographic sensor, aiming at simultaneous and selective response to multiple components following a chromatographic separation, is described. We report an improved approach for immobilization of octadecyl (C(18)) and methyl (C(1)) moieties as stationary phase on an optical fiber suitable as a sensing phase for organic solutes. By this approach, the stability and lifetime of the sensing layer as well as the detectability and retention behavior of the chromatographic sensor could be improved. Infrared spectroscopy was employed to confirm the presence of C(18) and C(1) moieties on the modified surface of the optical fiber. The chromatographic sensor was applied, with good sensitivity and chemical selectivity, to the simultaneous separation and detection of bromobenzene and toluene, using water as the mobile phase.

Sequential selection of economic good and action in medial frontal cortex of macaques during value-based decisions

PubMed Central

Chen, Xiaomo; Stuphorn, Veit

2015-01-01

Value-based decisions could rely either on the selection of desired economic goods or on the selection of the actions that will obtain the goods. We investigated this question by recording from the supplementary eye field (SEF) of monkeys during a gambling task that allowed us to distinguish chosen good from chosen action signals. Analysis of the individual neuron activity, as well as of the population state-space dynamic, showed that SEF encodes first the chosen gamble option (the desired economic good) and only ~100 ms later the saccade that will obtain it (the chosen action). The action selection is likely driven by inhibitory interactions between different SEF neurons. Our results suggest that during value-based decisions, the selection of economic goods precedes and guides the selection of actions. The two selection steps serve different functions and can therefore not compensate for each other, even when information guiding both processes is given simultaneously. DOI: http://dx.doi.org/10.7554/eLife.09418.001 PMID:26613409

Streptavidin Modified ZnO Film Bulk Acoustic Resonator for Detection of Tumor Marker Mucin 1

NASA Astrophysics Data System (ADS)

Zheng, Dan; Guo, Peng; Xiong, Juan; Wang, Shengfu

2016-09-01

A ZnO-based film bulk acoustic resonator has been fabricated using a magnetron sputtering technology, which was employed as a biosensor for detection of mucin 1. The resonant frequency of the thin-film bulk acoustic resonator was located near at 1503.3 MHz. The average electromechanical coupling factor {K}_{eff}^2 and quality factor Q were 2.39 % and 224, respectively. Using the specific binding system of avidin-biotin, the streptavidin was self-assembled on the top gold electrode as the sensitive layer to indirectly test the MUC1 molecules. The resonant frequency of the biosensor decreases in response to the mass loading in range of 20-500 nM. The sensor modified with the streptavidin exhibits a high sensitivity of 4642.6 Hz/nM and a good selectivity.

Application of ionic liquid in liquid phase microextraction technology.

PubMed

Han, Dandan; Tang, Baokun; Lee, Yu Ri; Row, Kyung Ho

2012-11-01

Ionic liquids (ILs) are novel nonmolecular solvents. Their unique properties, such as high thermal stability, tunable viscosity, negligible vapor pressure, nonflammability, and good solubility for inorganic and organic compounds, make them excellent candidates as extraction media for a range of microextraction techniques. Many physical properties of ILs can be varied, and the structural design can be tuned to impart the desired functionality and enhance the analyte extraction selectivity, efficiency, and sensitivity. This paper provides an overview of the applications of ILs in liquid phase microextraction technology, such as single-drop microextraction, hollow fiber based liquid phase microextraction, and dispersive liquid-liquid microextraction. The sensitivity, linear calibration range, and detection limits for a range of target analytes in the methods were analyzed to determine the advantages of ILs in liquid phase microextraction. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zwitterionic peptide anchored to conducting polymer PEDOT for the development of antifouling and ultrasensitive electrochemical DNA sensor.

PubMed

Wang, Guixiang; Han, Rui; Su, Xiaoli; Li, Yinan; Xu, Guiyun; Luo, Xiliang

2017-06-15

Zwitterionic peptides were anchored to a conducting polymer of citrate doped poly(3,4-ethylenedioxythiophene) (PEDOT) via the nickel cation coordination, and the obtained peptide modified PEDOT, with excellent antifouling ability and good conductivity, was further used for the immobilization of a DNA probe to construct an electrochemical biosensor for the breast cancer marker BRCA1. The DNA biosensor was highly sensitive (with detection limit of 0.03fM) and selective, and it was able to detect BRCA1 in 5% (v/v) human plasma with satisfying accuracy and low fouling. The marriage of antifouling and biocompatible peptides with conducting polymers opened a new avenue to construct electrochemical biosensors capable of assaying targets in complex biological media with high sensitivity and without biofouling. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterizing a porous road pavement using surface impedance measurement: a guided numerical inversion procedure.

PubMed

Benoit, Gaëlle; Heinkélé, Christophe; Gourdon, Emmanuel

2013-12-01

This paper deals with a numerical procedure to identify the acoustical parameters of road pavement from surface impedance measurements. This procedure comprises three steps. First, a suitable equivalent fluid model for the acoustical properties porous media is chosen, the variation ranges for the model parameters are set, and a sensitivity analysis for this model is performed. Second, this model is used in the parameter inversion process, which is performed with simulated annealing in a selected frequency range. Third, the sensitivity analysis and inversion process are repeated to estimate each parameter in turn. This approach is tested on data obtained for porous bituminous concrete and using the Zwikker and Kosten equivalent fluid model. This work provides a good foundation for the development of non-destructive in situ methods for the acoustical characterization of road pavements.

Ultrasensitive Label-free Electrochemical Immunosensor based on Multifunctionalized Graphene Nanocomposites for the Detection of Alpha Fetoprotein

PubMed Central

Wang, Yaoguang; Zhang, Yong; Wu, Dan; Ma, Hongmin; Pang, Xuehui; Fan, Dawei; Wei, Qin; Du, Bin

2017-01-01

In this work, a novel label-free electrochemical immunosensor was developed for the quantitative detection of alpha fetoprotein (AFP). Multifunctionalized graphene nanocomposites (TB-Au-Fe3O4-rGO) were applied to modify the electrode to achieve the amplification of electrochemical signal. TB-Au-Fe3O4-rGO includes the advantages of graphene, ferroferric oxide nanoparticles (Fe3O4 NPs), gold nanoparticles (Au NPs) and toluidine blue (TB). As a kind of redox probe, TB can produce the electrochemical signal. Graphene owns large specific surface area, high electrical conductivity and good adsorption property to load a large number of TB. Fe3O4 NPs have good electrocatalytic performance towards the redox of TB. Au NPs have good biocompatibility to capture the antibodies. Due to the good electrochemical performance of TB-Au-Fe3O4-rGO, the effective and sensitive detection of AFP was achieved by the designed electrochemical immunosensor. Under optimal conditions, the designed immunosensor exhibited a wide linear range from 1.0 × 10−5 ng/mL to 10.0 ng/mL with a low detection limit of 2.7 fg/mL for AFP. It also displayed good electrochemical performance including good reproducibility, selectivity and stability, which would provide potential applications in the clinical diagnosis of other tumor markers. PMID:28186128

A Niche-Based Framework to Assess Current Monitoring of European Forest Birds and Guide Indicator Species' Selection

PubMed Central

Wade, Amy S. I.; Barov, Boris; Burfield, Ian J.; Gregory, Richard D.; Norris, Ken; Vorisek, Petr; Wu, Taoyang; Butler, Simon J.

2014-01-01

Concern that European forest biodiversity is depleted and declining has provoked widespread efforts to improve management practices. To gauge the success of these actions, appropriate monitoring of forest ecosystems is paramount. Multi-species indicators are frequently used to assess the state of biodiversity and its response to implemented management, but generally applicable and objective methodologies for species' selection are lacking. Here we use a niche-based approach, underpinned by coarse quantification of species' resource use, to objectively select species for inclusion in a pan-European forest bird indicator. We identify both the minimum number of species required to deliver full resource coverage and the most sensitive species' combination, and explore the trade-off between two key characteristics, sensitivity and redundancy, associated with indicators comprising different numbers of species. We compare our indicator to an existing forest bird indicator selected on the basis of expert opinion and show it is more representative of the wider community. We also present alternative indicators for regional and forest type specific monitoring and show that species' choice can have a significant impact on the indicator and consequent projections about the state of the biodiversity it represents. Furthermore, by comparing indicator sets drawn from currently monitored species and the full forest bird community, we identify gaps in the coverage of the current monitoring scheme. We believe that adopting this niche-based framework for species' selection supports the objective development of multi-species indicators and that it has good potential to be extended to a range of habitats and taxa. PMID:24819734

Determination of trace levels of benzophenone-type ultra-violet filters in real matrices by bar adsorptive micro-extraction using selective sorbent phases.

PubMed

Almeida, C; Stępkowska, A; Alegre, A; Nogueira, J M F

2013-10-11

Bar adsorptive micro-extraction (BAμE), using selective sorbent phases, followed by liquid desorption in combination with high performance liquid chromatography-diode array detection (BAμE-LD/HPLC-DAD), is proposed for the determination of trace levels of four benzophenone-type UV filters (benzophenone, 2-hydroxy-4-methoxy-benzophenone, 2,4-hydroxybenzophenone and 4-hydroxybenzophenone) in real matrices. By comparing three polymers (P1, P2 and P3) and five activated carbons (AC1, AC2, AC3, AC4 and AC5) phases, P2 (a modified pyrrolidone polymer) and AC4 coatings showed much higher selectivity and capacity through BAμE, where the former offers multiple mechanisms of interaction and faster equilibrium kinetics. Assays performed on 25mL of ultra-pure water samples spiked at the 8.0μg/L level, yielded recoveries ranging from 76.6±8.3% to 103.5±6.4% depending on the sorbent phase used (P2 or AC4), under optimized experimental conditions. The analytical performance showed convenient detection limits (0.3-0.5μg/L) and good linear dynamic ranges (1.0-24.0μg/L) with remarkable determination coefficients (r(2)>0.9969). Excellent repeatability was also achieved through intraday (RSD<13.0%) and interday (RSD<8.9%) experiments. By using the standard addition methodology, the application of the present analytical approach on sea water, wastewater, commercial cosmetic products and urine samples revealed good sensitivity, absence of matrix effects and the occurrence of levels of some benzophenones. The proposed methodology that uses nanostructured particles and operates under the floating sampling technology proved to be a sorption-based static micro-extraction alternative to monitor benzophenone-type UV filters in real matrices. Moreover, is easy to implement, reliable, sensitive, requiring low sample volume and the possibility to choose the most selective sorbent coating according to the target compounds involved. Copyright © 2013. Published by Elsevier B.V.

Evaluation of markers for CpG island methylator phenotype (CIMP) in colorectal cancer by a large population-based sample.

PubMed

Ogino, Shuji; Kawasaki, Takako; Kirkner, Gregory J; Kraft, Peter; Loda, Massimo; Fuchs, Charles S

2007-07-01

The CpG island methylator phenotype (CIMP or CIMP-high) with extensive promoter methylation is a distinct phenotype in colorectal cancer. However, a choice of markers for CIMP has been controversial. A recent extensive investigation has selected five methylation markers (CACNA1G, IGF2, NEUROG1, RUNX3, and SOCS1) as surrogate markers for epigenomic aberrations in tumor. The use of these markers as a CIMP-specific panel needs to be validated by an independent, large dataset. Using MethyLight assays on 920 colorectal cancers from two large prospective cohort studies, we quantified DNA methylation in eight CIMP-specific markers [the above five plus CDKN2A (p16), CRABP1, and MLH1]. A CIMP-high cutoff was set at > or = 6/8 or > or = 5/8 methylated promoters, based on tumor distribution and BRAF/KRAS mutation frequencies. All but two very specific markers [MLH1 (98% specific) and SOCS1 (93% specific)] demonstrated > or = 85% sensitivity and > or = 80% specificity, indicating overall good concordance in methylation patterns and good performance of these markers. Based on sensitivity, specificity, and false positives and negatives, the eight markers were ranked in order as: RUNX3, CACNA1G, IGF2, MLH1, NEUROG1, CRABP1, SOCS1, and CDKN2A. In conclusion, a panel of markers including at least RUNX3, CACNA1G, IGF2, and MLH1 can serve as a sensitive and specific marker panel for CIMP-high.

Spectroscopic quantification of 5-hydroxymethylcytosine in genomic DNA using boric acid-functionalized nano-microsphere fluorescent probes.

PubMed

Chen, Hua-Yan; Wei, Jing-Ru; Pan, Jiong-Xiu; Zhang, Wei; Dang, Fu-Quan; Zhang, Zhi-Qi; Zhang, Jing

2017-05-15

5-hydroxymethylcytosine (5hmC) is the sixth base of DNA. It is involved in active DNA demethylation and can be a marker of diseases such as cancer. In this study, we developed a simple and sensitive 2-(4-boronophenyl)quinoline-4-carboxylic acid modified poly (glycidyl methacrylate (PBAQA-PGMA) fluorescent probe to detect the 5hmC content of genomic DNA based on T4 β-glucosyltransferase-catalyzed glucosylation of 5hmC. The fluorescence-enhanced intensity recorded from the DNA sample was proportional to its 5-hydroxymethylcytosine content and could be quantified by fluorescence spectrophotometry. The developed probe showed good detection sensitivity and selectivity and a good linear relationship between the fluorescence intensity and the concentration of 5 hmC within a 0-100nM range. Compared with other fluorescence detection methods, this method not only could determine trace amounts of 5 hmC from genomic DNA but also could eliminate the interference of fluorescent dyes and the need for purification. It also could avoid multiple labeling. Because the PBAQA-PGMA probe could enrich the content of glycosyl-5-hydroxymethyl-2-deoxycytidine from a complex ground substance, it will broaden the linear detection range and improve sensitivity. The limit of detection was calculated to be 0.167nM after enrichment. Furthermore, the method was successfully used to detect 5-hydroxymethylcytosine from mouse tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

Uniform manganese hexacyanoferrate hydrate nanocubes featuring superior performance for low-cost supercapacitors and nonenzymatic electrochemical sensors.

PubMed

Pang, Huan; Zhang, Yizhou; Cheng, Tao; Lai, Wen-Yong; Huang, Wei

2015-10-14

Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity.

Synthesis and Antiproliferative Activity of 2,5-bis(3′-Indolyl)pyrroles, Analogues of the Marine Alkaloid Nortopsentin

PubMed Central

Carbone, Anna; Parrino, Barbara; Barraja, Paola; Spanò, Virginia; Cirrincione, Girolamo; Diana, Patrizia; Maier, Armin; Kelter, Gerhard; Fiebig, Heinz-Herbert

2013-01-01

2,5-bis(3′-Indolyl)pyrroles, analogues of the marine alkaloid nortopsentin, were conveniently prepared through a three step procedure in good overall yields. Derivatives 1a and 1b exhibited concentration-dependent antitumor activity towards a panel of 42 human tumor cell lines with mean IC50 values of 1.54 μM and 0.67 μM, respectively. Investigating human tumor xenografts in an ex-vivo clonogenic assay revealed selective antitumor activity, whereas sensitive tumor models were scattered among various tumor histotypes. PMID:23455514

[Design and optical principles of multifocal lenses].

PubMed

Auffarth, G U; Rabsilber, T M; Kohnen, T; Holzer, M P

2008-06-01

Multifocal intraocular lenses (MIOLs) of different designs have been used for more than 20 years in modern cataract surgery. The first IOLs were either refractive 2-3-zone designs or of diffractive concept. All MIOL types, regardless of manufacturer, show reduced contrast sensitivity and increased glare for years. Nevertheless, even first-generation MIOL patients had very good functional results when patient selection, IOL calculation, and surgical techniques were appropriate. Today's gold standard is foldable, aspherical diffractive, or refractive MIOLS. Advancements in technology allow the possibility that MIOLs will be used for aphakia correction as well as presbyopia correction.

Nitrosation of aryl and heteroaryltrifluoroborates with nitrosonium tetrafluoroborate.

PubMed

Molander, Gary A; Cavalcanti, Livia N

2012-05-04

Organotrifluoroborates have emerged as an alternative to toxic and air- and moisture-sensitive organometallic species for the synthesis of functionalized aryl and heteroaryl compounds. It has been shown that the trifluoroborate moiety can be easily converted into a variety of different substituents in a late synthetic stage. In this paper, we disclose a mild, selective, and convenient method for the ipso-nitrosation of organotrifluoroborates using nitrosonium tetrafluoroborate (NOBF(4)). Aryl- and heteroaryltrifluoroborates were converted into the corresponding nitroso products in good to excellent yields. This method proved to be tolerant of a broad range of functional groups.

NITROSATION OF ARYL AND HETEROARYLTRIFLUOROBORATES WITH NITROSONIUM TETRAFLUOROBORATE

PubMed Central

Cavalcanti, Livia N.

2012-01-01

Organotrifluoroborates have emerged as an alternative to toxic and air- and moisture sensitive organometallic species for the synthesis of functionalized aryl and heteroaryl compounds. It has been shown that the trifluoroborate moiety can be easily converted into a variety of different substituents in a late synthetic stage. In this paper we disclose a mild, selective, and convenient method for the ipso-nitrosation of organotrifluoroborates using nitrosonium tetrafluoroborate (NOBF4). Aryl- and heteroaryltrifluoroborates were converted into the corresponding nitroso products in good to excellent yields. This method proved to be tolerant of a broad range of functional groups. PMID:22524190

[Application of password manager software in health care].

PubMed

Ködmön, József

2016-12-01

When using multiple IT systems, handling of passwords in a secure manner means a potential source of problem. The most frequent issues are choosing the appropriate length and complexity, and then remembering the strong passwords. Password manager software provides a good solution for this problem, while greatly increasing the security of sensitive medical data. This article introduces a password manager software and provides basic information of the application. It also discusses how to select a really secure password manager software and suggests a practical application to efficient, safe and comfortable use for health care. Orv. Hetil., 2016, 157(52), 2066-2073.

[Genetic improvement of technological characteristics of starters for fermented milk products].

PubMed

Oganesian, G G; Barsegian, A A; Grigorian, N G; Toptsian, A V

2010-01-01

Possibility for improvement of technological characteristics of lactobacilli using mutations of resistance to rifampicin (rif(r)) and streptomycin (str(r)) was studied. Using starter model of Narine Lactobacillus acidophilus INMIA-9602 Armenian diet milk product, it was showed that a possibility for selecting strains with increased rate of milk fermentation and acid production is higher in Rif(r) and Str(r) mutants induced by nitrosoguanidine than in cultures sensitive to antibiotics. The milk products obtained using Rif(r) and Str(r) strains had high viscosity, improved texture, increased amount of alive cells and good organoleptic features.

Improvement of sensitive CuO NFs-ITO nonenzymatic glucose sensor based on in situ electrospun fiber.

PubMed

Liu, Guangyue; Zheng, Baozhan; Jiang, Yanshu; Cai, Yuqing; Du, Juan; Yuan, Hongyan; Xiao, Dan

2012-11-15

CuO nanofibers (NFs), prepared by electrospinning and calcination technologies, have been applied for the fabrication of glucose sensors with high sensitivity and selectivity. Cu(NO(3))(2) and polyvinylpyrrolidone (PVP) composite nanofibers were initially electrospun on the surface of indium tin oxide (ITO) glass, and then the CuO NFs-ITO electrode was formed simply by removing PVP through heat treatment. The structures and morphologies of CuO nanofibers were characterized by X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. The direct electrocatalytic oxidation of glucose in alkaline medium at CuO NFs-ITO electrode has also been investigated in detail with cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The effects of NaOH concentration, electrospinning time, Cu(NO(3))(2):PVP mass ratios and calcination temperature on the response to glucose were investigated. Under optimized experimental conditions, the CuO NFs-ITO electrode produced high and reproducible sensitivity to glucose of 873 μA mM(-1)cm(-2). Linear responses were obtained over a concentration range from 0.20 μM to 1.3mM with a detection limit of 40 nM (S/N=3). The CuO NFs-ITO electrode also has good selectivity, stability and fast amperometic sensing of glucose, thus it can be used for the future development of non-enzymatic glucose sensors. Copyright © 2012 Elsevier B.V. All rights reserved.

Room Temperature Sensing Achieved by GaAs Nanowires and oCVD Polymer Coating.

PubMed

Wang, Xiaoxue; Ermez, Sema; Goktas, Hilal; Gradečak, Silvija; Gleason, Karen

2017-06-01

Novel structures comprised of GaAs nanowire arrays conformally coated with conducting polymers (poly(3,4-ethylenedioxythiophene) (PEDOT) or poly(3,4-ethylenedioxythiophene-co-3-thiophene acetic acid) display both sensitivity and selectivity to a variety of volatile organic chemicals. A key feature is room temperature operation, so that neither a heater nor the power it would consume, is required. It is a distinct difference from traditional metal oxide sensors, which typically require elevated operational temperature. The GaAs nanowires are prepared directly via self-seeded metal-organic chemical deposition, and conducting polymers are deposited on GaAs nanowires using oxidative chemical vapor deposition (oCVD). The range of thickness for the oCVD layer is between 100 and 200 nm, which is controlled by changing the deposition time. X-ray diffraction analysis indicates an edge-on alignment of the crystalline structure of the PEDOT coating layer on GaAs nanowires. In addition, the positive correlation between the improvement of sensitivity and the increasing nanowire density is demonstrated. Furthermore, the effect of different oCVD coating materials is studied. The sensing mechanism is also discussed with studies considering both nanowire density and polymer types. Overall, the novel structure exhibits good sensitivity and selectivity in gas sensing, and provides a promising platform for future sensor design. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sensitive detection of alkaline phosphatase by switching on gold nanoclusters fluorescence quenched by pyridoxal phosphate.

PubMed

Halawa, Mohamed Ibrahim; Gao, Wenyue; Saqib, Muhammad; Kitte, Shimeles Addisu; Wu, Fengxia; Xu, Guobao

2017-09-15

In this work, we designed highly sensitive and selective luminescent detection method for alkaline phosphatase using bovine serum albumin functionalized gold nanoclusters (BSA-AuNCs) as the nanosensor probe and pyridoxal phosphate as the substrate of alkaline phosphatase. We found that pyridoxal phosphate can quench the fluorescence of BSA-AuNCs and pyridoxal has little effect on the fluorescence of BSA-AuNCs. The proposed mechanism of fluorescence quenching by PLP was explored on the basis of data obtained from high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), UV-vis spectrophotometry, fluorescence spectroscopy, fluorescence decay time measurements and circular dichroism (CD) spectroscopy. Alkaline phosphatase catalyzes the hydrolysis of pyridoxal phosphate to generate pyridoxal, restoring the fluorescence of BSA-AuNCs. Therefore, a recovery type approach has been developed for the sensitive detection of alkaline phosphatase in the range of 1.0-200.0U/L (R 2 =0.995) with a detection limit of 0.05U/L. The proposed sensor exhibit excellent selectivity among various enzymes, such as glucose oxidase, lysozyme, trypsin, papain, and pepsin. The present switch-on fluorescence sensing strategy for alkaline phosphatase was successfully applied in human serum plasma with good recoveries (100.60-104.46%), revealing that this nanosensor probe is a promising tool for ALP detection. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

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

2018-05-10

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

Polyhydroquinone-graphene composite as new redox species for sensitive electrochemical detection of cytokeratins antigen 21-1

NASA Astrophysics Data System (ADS)

Wang, Huiqiang; Rong, Qinfeng; Ma, Zhanfang

2016-07-01

Polyhydroquinone-graphene composite as a new redox species was synthesized simply by a microwave-assisted one-pot method through oxidative polymerization of hydroquinone by graphene oxide, which exhibited excellent electrochemical redox activity at 0.124 V and can remarkably promote electron transfer. The as-prepared composite was used as immunosensing substrate in a label-free electrochemical immunosensor for the detection of cytokeratins antigen 21-1, a kind of biomarker of lung cancer. The proposed immunosensor showed wide liner range from 10 pg mL-1 to 200 ng mL-1 with a detection limit 2.3 pg mL-1, and displayed a good stability and selectivity. In addition, this method has been used for the analysis of human serum sample, and the detection results showed good consistence with those of ELISA. The present substrate can be easily extended to other polymer-based nanocomposites.

[Fully implantable hearing systems].

PubMed

Maurer, J

2009-03-01

As yet comparatively little experience has been gained with fully implantable hearing systems, as the two systems available at present have only recently received CE permission for Europe and the FDA permissions are still pending in the USA. Additionally the technology is expensive and usually not covered by insurance companies. However, it could be shown that by careful patient selection and very careful surgical techniques, good results can be achieved with this highly sensitive technology, often with better patient satisfaction and hearing quality than with conventional hearing aids. To spread the technology further, the systems must also show reliable results on a broad application. Further surgery to change the batteries should not be necessary more frequently than with cardiac pacemakers. Not all technical problems are finally solved. However, it is to be foreseen that fully implantable hearing systems will be a good long-term alternative to conventional hearing aids for some patients.

Prediction of pelvic organ prolapse using an artificial neural network.

PubMed

Robinson, Christopher J; Swift, Steven; Johnson, Donna D; Almeida, Jonas S

2008-08-01

The objective of this investigation was to test the ability of a feedforward artificial neural network (ANN) to differentiate patients who have pelvic organ prolapse (POP) from those who retain good pelvic organ support. Following institutional review board approval, patients with POP (n = 87) and controls with good pelvic organ support (n = 368) were identified from the urogynecology research database. Historical and clinical information was extracted from the database. Data analysis included the training of a feedforward ANN, variable selection, and external validation of the model with an independent data set. Twenty variables were used. The median-performing ANN model used a median of 3 (quartile 1:3 to quartile 3:5) variables and achieved an area under the receiver operator curve of 0.90 (external, independent validation set). Ninety percent sensitivity and 83% specificity were obtained in the external validation by ANN classification. Feedforward ANN modeling is applicable to the identification and prediction of POP.

Design of Diaphragm and Coil for Stable Performance of an Eddy Current Type Pressure Sensor.

PubMed

Lee, Hyo Ryeol; Lee, Gil Seung; Kim, Hwa Young; Ahn, Jung Hwan

2016-07-01

The aim of this work was to develop an eddy current type pressure sensor and investigate its fundamental characteristics affected by the mechanical and electrical design parameters of sensor. The sensor has two key components, i.e., diaphragm and coil. On the condition that the outer diameter of sensor is 10 mm, two key parts should be designed so as to keep a good linearity and sensitivity. Experiments showed that aluminum is the best target material for eddy current detection. A round-grooved diaphragm is suggested in order to measure more precisely its deflection caused by applied pressures. The design parameters of a round-grooved diaphragm can be selected depending on the measuring requirements. A developed pressure sensor with diaphragm of t = 0.2 mm and w = 1.05 mm was verified to measure pressure up to 10 MPa with very good linearity and errors of less than 0.16%.

Fast response of carbon monoxide gas sensors using a highly porous network of ZnO nanoparticles decorated on 3D reduced graphene oxide

NASA Astrophysics Data System (ADS)

Ha, Nguyen Hai; Thinh, Dao Duc; Huong, Nguyen Thanh; Phuong, Nguyen Huy; Thach, Phan Duy; Hong, Hoang Si

2018-03-01

Zinc oxide (ZnO) nanoparticles loaded onto 3D reduced graphene oxide (3D-RGO) for carbon monoxide (CO) sensing were synthesized using hydrothermal method. The highly porous ZnO/3D-RGO configuration was stable without collapsing and was deposited on the micro-heater of the CO gas sensor. The resulting CO gas sensor displayed high sensitivity, fast response/recovery, and good linearity. The sensor achieved a response value of 85.2% for 1000 ppm CO at a working temperature of 200 °C. The response and recovery times of the sensor were 7 and 9 s for 1000 ppm CO at 200 °C. Similarly, the response value, response time, and recovery time of the sensor at room temperature were 27.5%, 14 s, and 15 s, respectively. The sensor demonstrated a distinct response to various CO concentrations in the range of 1-1000 ppm and good selectivity toward CO gas. In addition, the sensor exhibited good repeatability in multi-cycle and long-term stability.

Electro-focusing liquid extractive surface analysis (EF-LESA) coupled to mass spectrometry.

PubMed

Brenton, A Gareth; Godfrey, A Ruth

2014-04-01

Analysis of the chemical composition of surfaces by liquid sampling devices interfaced to mass spectrometry is attractive as the sample stream can be continuously monitored at good sensitivity and selectivity. A sampling probe has been constructed that takes discrete liquid samples (typically <100 nL) of a surface. It incorporates an electrostatic lens system, comprising three electrodes, to which static and pulsed voltages are applied to form a conical "liquid tip", employed to dissolve analytes at a surface. A prototype system demonstrates spatial resolution of 0.093 mm(2). Time of contact between the liquid tip and the surface is controlled to standardize extraction. Calibration graphs of different analyte concentrations on a stainless surface have been measured, together with the probe's reproducibility, carryover, and recovery. A leucine enkephalin-coated surface demonstrated good linearity (R(2) = 0.9936), with a recovery of 90% and a limit of detection of 38 fmol per single spot sampled. The probe is compact and can be fitted into automated sample analysis equipment having potential for rapid analysis of surfaces at a good spatial resolution.

Electro-Focusing Liquid Extractive Surface Analysis (EF-LESA) Coupled to Mass Spectrometry

PubMed Central

2014-01-01

Analysis of the chemical composition of surfaces by liquid sampling devices interfaced to mass spectrometry is attractive as the sample stream can be continuously monitored at good sensitivity and selectivity. A sampling probe has been constructed that takes discrete liquid samples (typically <100 nL) of a surface. It incorporates an electrostatic lens system, comprising three electrodes, to which static and pulsed voltages are applied to form a conical “liquid tip”, employed to dissolve analytes at a surface. A prototype system demonstrates spatial resolution of 0.093 mm2. Time of contact between the liquid tip and the surface is controlled to standardize extraction. Calibration graphs of different analyte concentrations on a stainless surface have been measured, together with the probe’s reproducibility, carryover, and recovery. A leucine enkephalin-coated surface demonstrated good linearity (R2 = 0.9936), with a recovery of 90% and a limit of detection of 38 fmol per single spot sampled. The probe is compact and can be fitted into automated sample analysis equipment having potential for rapid analysis of surfaces at a good spatial resolution. PMID:24597530

Supplemental Screening for Breast Cancer in Women with Dense Breasts: A Systematic Review for the U.S. Preventive Services Task Force

PubMed Central

Melnikow, Joy; Fenton, Joshua J.; Whitlock, Evelyn P.; Miglioretti, Diana L.; Weyrich, Meghan S.; Thompson, Jamie H.; Shah, Kunal

2016-01-01

Background Screening mammography has lower sensitivity and specificity in women with dense breasts, who experience higher breast cancer risk. Purpose Systematic review of: reproducibility of BI-RADS density categorization; test performance and clinical outcomes of supplemental screening with breast ultrasound, magnetic resonance imaging (MRI), and digital breast tomosynthesis (DBT) in women with dense breasts and negative mammography. Data Sources MEDLINE, PubMed, Embase, and Cochrane January 2000–July 2015. Study Selection Studies reporting BI-RADS density reproducibility or supplemental screening results for women with dense breasts. Data Extraction Quality assessment and abstraction of twenty-four studies from seven countries; six were good quality. Data Synthesis Three good-quality studies reported reproducibility of BI-RADS density; 13–19% of women were re-categorized between “dense” and “non-dense” at subsequent screening. Two good-quality studies reported ultrasound sensitivity for women with negative mammography ranging from 80–83%; specificity 86–94%; and positive predictive value (PPV) 3–8%. MRI sensitivity ranged from 75–100%, specificity 78–94%, and PPV 3–33% (3 studies). Ultrasound additional cancer detection rates were 4.4 per 1,000 exams (89–93% invasive); recall rates were 14%. MRI detected 3.5–28.6 additional cancers per 1,000 exams (34–86% invasive); recall rates were 12–24 %. DBT cancer detection rates increased by 1.4–2.5 per 1000 exams compared to mammography alone (3 studies). Recall rates ranged from 7–11%, compared to 7–17% with mammography alone. No studies examined breast cancer outcomes. Limitations Good quality evidence was sparse. Studies were small and confidence intervals were wide. Definitions of recall were absent or inconsistent. Conclusions Density ratings may be re-categorized on serial screening mammograms. Supplemental screening of women with dense breasts finds additional breast cancers, but increases false-positives. DBT may reduce recall rates. Supplemental screening impacts on breast cancer outcomes remain unclear. Primary Funding Source Agency for Healthcare Research and Quality PMID:26757021

The clinical features of squamous cell lung carcinoma with sensitive EGFR mutations.

PubMed

Taniguchi, Yuri; Matsumoto, Yoko; Furukawa, Ryutaro; Ohara, Sayaka; Usui, Kazuhiro

2018-06-01

The process of selecting patients on the basis of epidermal growth factor receptor (EGFR) mutations would likely result in a patient population with greater sensitivity to EGFR tyrosine kinase inhibitors (EGFR-TKIs). However, EGFR mutation status is not routinely examined in patients with squamous cell lung cancer (Sq) because of the low incidence of EGFR mutations and the poor clinical response to EGFR-TKIs. We retrospectively reviewed the clinical features of patients at our hospital with Sq who carried EGFR-TKI-sensitive EGFR mutations and assessed their responses to EGFR-TKIs. EGFR mutation status was tested in 23 of 441 patients with Sq (5.2%) admitted to our hospital during the study period. An EGFR mutation (exon 19 deletion 3, L858R 2) was identified in five of the 23 patients (21.7%), all of whom were female never-smokers. Of these five patients, four (4/9; 44.4%) were in the normal lung group, one (1/12; 8.3%) was in the emphysematous lung group, and none (0/2; 0%) in the fibrotic lung group. Two of these five patients with the EGFR mutation received gefitinib and two received afatinib. Although the two patients who were treated with gefitinib did not respond well to treatment (stable disease, 1 patient; progressive disease, 1 patient), the two patients who were treated with afatinib showed a good response (partial response, 2 patients). The administration of afatinib to Sq patients after selecting patients using the EGFR mutation test based on their underlying pulmonary disease and smoking status would likely result in a population with a greater sensitivity to afatinib.

Design and Investigation of Optical Properties of N-(Rhodamine-B)-Lactam-Ethylenediamine (RhB-EDA) Fluorescent Probe.

PubMed

Soršak, Eva; Volmajer Valh, Julija; Korent Urek, Špela; Lobnik, Aleksandra

2018-04-14

This study presents chemical modification of a Rhodamine B (RhB) sensor probe by ethylenediamine (EDA), and investigation of its spectral as well as sensor properties to the various metals. The synthesised N -(Rhodamine-B)-lactam-ethylenediamine (RhB-EDA) fluorescent probe shows interesting optical sensor properties, and high sensitivity and selectivity to Ag⁺ ions among all the tested metal ions (K⁺, Mg 2+ , Cu 2+ , Ni 2+ , Fe 2+ , Pb 2+ , Na⁺, Mn 2+ , Li⁺, Al 3+ , Co 2+ , Hg 2+ , Sr 2+ , Ca 2+ , Ag⁺, Cd 2+ and Zn 2+ ), while the well-known Rhodamine B (RhB) fluorescent probe shows much less sensitivity to Ag⁺ ions, but high sensitivity to Fe 2+ ions. The novel fluorescent sensor probe RhB-EDA has the capabilities to sense Ag⁺ ions up to µM ranges by using the fluorescence quenching approach. The probe displayed a dynamic response to Ag⁺ in the range of 0.43 × 10 -3 -10 -6 M with a detection limit of 0.1 μM. The sensing system of an RhB-EDA novel fluorescent probe was optimised according to the spectral properties, effect of pH and buffer, photostability, incubation time, sensitivity, and selectivity. Since all the spectral and sensing properties were tested in green aqueous media, although many other similar sensor systems rely on organic solvent solutions, the RhB-EDA sensing probe may be a good candidate for measuring Ag⁺ ions in real-life applications.

High-performance iron oxide nanoparticles for magnetic particle imaging - guided hyperthermia (hMPI)

NASA Astrophysics Data System (ADS)

Bauer, Lisa M.; Situ, Shu F.; Griswold, Mark A.; Samia, Anna Cristina S.

2016-06-01

Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI).Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI). Electronic supplementary information (ESI) available: Detailed IONP synthetic methods, description of magnetic particle relaxometer set-up, TEM of reference IONP (Senior Scientific PrecisionMRX™ 25 nm oleic acid-coated nanoparticles), concentration dependent PSF of all IONP samples, PSF and SAR of Zn-Sph and Zn-Cube mixture sample, upper right quadrant of field-dependent hysteresis curve labelled with static field strengths, and the magnetic hyperthermia temperature profiles with and without the presence of external magnetic fields. See DOI: 10.1039/c6nr01877g

Determination of trace levels of parabens in real matrices by bar adsorptive microextraction using selective sorbent phases.

PubMed

Almeida, C; Nogueira, J M F

2014-06-27

In the present work, the development of an analytical methodology which combines bar adsorptive microextraction with microliquid desorption followed by high performance liquid chromatography-diode array detection (BAμE-μLD/HPLC-DAD) is proposed for the determination of trace levels of four parabens (methyl, ethyl, propyl and buthyl paraben) in real matrices. By comparing six polymer (P1, P2, P3, P4, P5 and P6) and five activated carbon (AC1, AC2, AC3, AC4 and AC5) coatings through BAμE, AC2 exhibited much higher selectivity and efficiency from all the sorbent phases tested, even when compared with the commercial stir bar sorptive extraction with polydimethylsiloxane. Assays performed through BAμE(AC2, 1.7mg) on 25mL of ultrapure water samples spiked at the 8.0μg/L level, yielded recoveries ranging from 85.6±6.3% to 100.6±11.8%, under optimized experimental conditions. The analytical performance showed also convenient limits of detection (0.1μg/L) and quantification (0.3μg/L), as well as good linear dynamic ranges (0.5-28.0μg/L) with remarkable determination coefficients (r(2)>0.9982). Excellent repeatability was also achieved through intraday (RSD<10.2%) and interday (RSD<10.0%) assays. By downsizing the analytical device to half-length (BAμE(AC2, 0.9mg)), similar analytical data was also achieved for the four parabens, under optimized experimental conditions, showing that this analytical technology can be design to operate with lower volumes of sample and desorption solvent, thus increasing the sensitivity and effectiveness. The application of the proposed analytical approach using the standard addition methodology on tap, underground, estuarine, swimming pool and waste water samples, as well as on commercial cosmetic products and urine samples, revealed good sensitivity, absence of matrix effects and the occurrence of levels of some parabens. Moreover, the present methodology is easy to implement, reliable, sensitive, requiring low sample and minimized desorption solvent volume, having the possibility to tune the most selective sorbent coating, according to the target compounds involved. Copyright © 2014 Elsevier B.V. All rights reserved.

The impact of body condition after calving on metabolism and milk progesterone profiles in two breeds of dairy cows.

PubMed

O'Hara, Lisa A; Båge, Renée; Holtenius, Kjell

2016-10-20

Optimal body condition in early lactation is generally accepted as a prerequisite for good reproductive performance. Examination of milk progesterone profiles offers an objective method for characterization of postpartum ovarian activity in dairy cows. The present study investigated the relationship between body condition after calving, some metabolic parameters in blood plasma, and fertility, as reflected by milk progesterone profiles in the two dairy breeds Swedish Red (SR) and Swedish Holstein (SH). Multiparous dairy cows (n = 73) of SR and SH breeds were selected and divided into three groups based on their body condition score (BCS) after parturition. Selected plasma metabolites were determined, milk progesterone profiles were identified and body condition was scored. Over-conditioned cows and atypical progesterone profiles were more common among SR cows. Insulin sensitivity was lower and IGF 1 higher among SR cows. Insulin was positively related to body condition, but not related to breed. Atypical progesterone profiles were more common and insulin sensitivity lower in SR than in SH cows, but the SR breed had a higher proportion of over-conditioned SR cows. It is reasonable to assume that breed differences in body condition contributed to these results.

Application of graphene-ionic liquid-chitosan composite-modified carbon molecular wire electrode for the sensitive determination of adenosine-5'-monophosphate.

PubMed

Shi, Fan; Gong, Shixing; Xu, Li; Zhu, Huanhuan; Sun, Zhenfan; Sun, Wei

2013-12-01

In this paper, a graphene (GR) ionic liquid (IL) 1-octyl-3-methylimidazolium hexafluorophosphate and chitosan composite-modified carbon molecular wire electrode (CMWE) was fabricated by a drop-casting method and further applied to the sensitive electrochemical detection of adenosine-5'-monophosphate (AMP). CMWE was prepared with diphenylacetylene (DPA) as the modifier and the binder. The properties of modified electrode were examined by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical behaviors of AMP was carefully investigated with enhanced responses appeared, which was due to the presence of GR-IL composite on the electrode surface with excellent electrocatalytic ability. A well-defined oxidation peak of AMP appeared at 1.314 V and the electrochemical parameters were calculated by electrochemical methods. Under the selected conditions, the oxidation peak current of AMP was proportional to its concentration in the range from 0.01 μM to 80.0 μM with the detection limit as 3.42 nM (3σ) by differential pulse voltammetry. The proposed method exhibited good selectivity and was applied to the detection of vidarabine monophosphate injection samples with satisfactory results. © 2013.

A self-assembled fluorescent organic nanoprobe and its application for sulfite detection in food samples and living systems.

PubMed

Gao, Tang; Cao, Xiaozheng; Ge, Peng; Dong, Jie; Yang, Shuqi; Xu, Huan; Wu, Yong; Gao, Feng; Zeng, Wenbin

2017-05-23

Sulfur dioxide (SO 2 ) is a widely distributed air pollutant, and humans can easily be exposed to sulfite by inhaling SO 2 , thus inducing respiratory responses and diseases. Hence, to develop a rapid, sensitive and selective method for detection of sulfites is of great importance. Herein, we designed and synthesized a novel tetraphenyl imidazole compound TIBM with aggregation-induced emission enhancement (AIEE). TIBM can self-assemble into well-organized nanoparticles and is reported as an excellent probe for detection of sulfite with high selectivity and sensitivity. The nanoprobe performed very well for the detection of sulfite with an ultrafast detection time (15 s) and an ultralow detection limit (7.4 nM), which is superior to most of the reported probes. Moreover, the nanoprobe was successfully used to detect sulfite in food samples with a favorable accuracy. In addition, we developed paper-based devices for point-of-care detection of sulfite with naked eyes. Furthermore, due to its high water solubility, cell membrane permeability and good biocompatibility, the nanoproboe was further applied to detect sulfite in living systems. This study may offer some helpful insights for designing other AIE-based fluorescent nanosensors for various analytes.

An ultrasensitive and selective method for the determination of Ceftriaxone using cysteine capped cadmium sulfide fluorescence quenched quantum dots as fluorescence probes

NASA Astrophysics Data System (ADS)

Samadi, Naser; Narimani, Saeedeh

2016-06-01

In this paper, L-cysteine (Cys) coated CdS quantum dots (QDs) have been prepared, which have excellent water-solubility and are highly stable in aqueous solution. These QDs is proposed as sensitizers for the determination of Ceftriaxone. The quantum dot nanoparticles were structurally and optically characterized by Ultra Violet-Visible absorption Spectroscopy (UV-vis absorption spectroscopy), Fourier transform infrared spectroscopy (FT-IR spectra) and photoluminescence (PL) emission spectroscopy. High resolution transmission electron microscopy (HRTEM) confirms that the Cys-CdS QDs have a spherical structure with good crystallinity. Therefore, a new simple and selective PL analysis system was developed for the determination of Ceftriaxone (CFX). Under the optimum conditions, The response of L-Cys capped CdS QDs as the probe was linearly proportional to the concentration of Ceftriaxone ions in the range of 1.6 × 10- 9-1.1 × 10- 3 M with a correlation coefficient (R2) of 0.9902. The limit of detection of this system was found to be 1.3 nM. This method is simple, sensitive and low cost.

A highly selective colorimetric and ratiometric fluorescent probe for instantaneous sensing of Hg2+ in water, soil and seafood and its application on test strips.

PubMed

Lan, Linxin; Niu, Qingfen; Li, Tianduo

2018-09-06

A new simple and efficient oligothiophene-based colorimetric and ratiometric fluorescent probe has been developed for highly sensitive and fast detection of Hg 2+ in water, soil and seafood. The probe 5-(1,3-dithiolan-2-yl)-2,2':5',2″-terthiophene 3 TS can selectively detect Hg 2+ via the Hg 2+ -promoted deprotection reaction of thioacetals, which caused a remarkable color change from colorless to yellow and a strong fluorescence enhancement with emission color varying from blue to yellow, enabling naked-eye detection of Hg 2+ . The probe shows high sensitivity with the detection limit down to 1.03 × 10 -8  M. Visual color changes of 3 TS were observed on filter paper and TLC testing strips when they were impregnated on testing strips and immersed in Hg 2+ solution. Moreover, the probe 3 TS has been successfully used to rapidly detect trace amounts of hazardous Hg 2+ ions in tap, distilled, river and lake water, cropland soil, fish, shrimp and kelp samples with acceptable results and good recoveries. Copyright © 2018 Elsevier B.V. All rights reserved.

Automatic detection of obstructive sleep apnea using speech signals.

PubMed

Goldshtein, Evgenia; Tarasiuk, Ariel; Zigel, Yaniv

2011-05-01

Obstructive sleep apnea (OSA) is a common disorder associated with anatomical abnormalities of the upper airways that affects 5% of the population. Acoustic parameters may be influenced by the vocal tract structure and soft tissue properties. We hypothesize that speech signal properties of OSA patients will be different than those of control subjects not having OSA. Using speech signal processing techniques, we explored acoustic speech features of 93 subjects who were recorded using a text-dependent speech protocol and a digital audio recorder immediately prior to polysomnography study. Following analysis of the study, subjects were divided into OSA (n=67) and non-OSA (n=26) groups. A Gaussian mixture model-based system was developed to model and classify between the groups; discriminative features such as vocal tract length and linear prediction coefficients were selected using feature selection technique. Specificity and sensitivity of 83% and 79% were achieved for the male OSA and 86% and 84% for the female OSA patients, respectively. We conclude that acoustic features from speech signals during wakefulness can detect OSA patients with good specificity and sensitivity. Such a system can be used as a basis for future development of a tool for OSA screening. © 2011 IEEE

Highly sensitive and selective detection of Pb2+ using a turn-on fluorescent aptamer DNA silver nanoclusters sensor.

PubMed

Zhang, Baozhu; Wei, Chunying

2018-05-15

A novel turn-on fluorescent biosensor has been constructed using C-PS2.M-DNA-templated silver nanoclusters (Ag NCs) with an average diameter of about 1 nm. The proposed approach presents a low-toxic, simple, sensitive, and selective detection for Pb 2+ . The fluorescence intensity of C-PS2.M-DNA-Ag NCs enhances significantly in the presence of Pb 2+ , which is attributed to the special interaction between Pb 2+ and its aptamer DNA PS2.M. Pb 2+ induces the aptamer to form G-quadruplex and makes two darkish DNA/Ag NCs located at the 3' and 5' terminus close, resulting in the fluorescence light-up. Moreover, Pb 2+ can be detected as low as 3.0 nM within a good linear range from 5 to 50 nM (R = 0.9862). Furthermore, the application for detection of Pb 2+ in real water samples further demonstrates the reliability of the sensor. Thus, this sensor system shows a potential application for monitoring Pb 2+ in environmental samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Peroxyoxalate chemiluminescence detection for the highly sensitive determination of fluorescence-labeled chlorpheniramine with Suzuki coupling reaction.

PubMed

Adutwum, Lawrence Asamoah; Kishikawa, Naoya; Ohyama, Kaname; Harada, Shiro; Nakashima, Kenichiro; Kuroda, Naotaka

2010-09-01

A sensitive and selective high performance liquid chromatography-peroxyoxalate chemiluminescence (PO-CL) method has been developed for the simultaneous determination of chlorpheniramine (CPA) and monodesmethyl chlorpheniramine (MDCPA) in human serum. The method combines fluorescent labeling with 4-(4,5-diphenyl-1H-imidazole-2-yl)phenyl boronic acid using Suzuki coupling reaction with PO-CL detection. CPA and MDCPA were extracted from human serum by liquid-liquid extraction with n-hexane. Excess labeling reagent, which interfered with trace level determination of analytes, was removed by solid-phase extraction using a C18 cartridge. Separation of derivatives of both analytes was achieved isocratically on a silica column with a mixture of acetonitrile and 60 mM imidazole-HNO(3) buffer (pH 7.2; 85:15, v/v) containing 0.015% triethylamine. The proposed method exhibited a good linearity with a correlation coefficient of 0.999 for CPA and MDCPA within the concentration range of 0.5-100 ng/mL. The limits of detection (S/N = 3) were 0.14 and 0.16 ng/mL for CPA and MDCPA, respectively. Using the proposed method, CPA could be selectively determined in human serum after oral administration.

Colloidal GdVO4:Eu3+@SiO2 nanocrystals for highly selective and sensitive detection of Cu2+ ions

NASA Astrophysics Data System (ADS)

Liang, Yanjie; Noh, Hyeon Mi; Park, Sung Heum; Choi, Byung Chun; Jeong, Jung Hyun

2018-03-01

Nowadays, in view of health and safety demands, the controlled design of selective and sensitive sensors for Cu2+ detection is of considerable importance. Therefore, we construct herein core-shell colloidal GdVO4:Eu3+@SiO2 nanocrystals (NCs) as optical sensor for the detection of Cu2+, which were synthesized by a facile hydrothermal reaction and encapsulated with a uniform layer of ultrathin silica through a sol-gel strategy. The NCs present strong red emission due to energy transfer from VO43- groups to Eu3+ when exciting with ultraviolet (UV) light. This intense red emission from Eu3+ could be selectively quenched in the presence of Cu2+ in comparison to other metal ions and the limit of detection is as low as 80 nM in aqueous solution. It is revealed that the spectral overlap between the emission band of NCs and the absorption of Cu2+ accounts for this intriguing luminescence behavior. The detection ability is highly reversible by the addition of ethylenediaminetetraacetic acid (EDTA) with the recovery of almost 100% of the original luminescence. The luminescence quenching and recovery processes can be performed repeatedly with good sensing ability. These remarkable performances allow the colloidal GdVO4:Eu3+@SiO2 NCs a promising fluorescence chemosensor for detecting Cu2+ ions in aqueous solution.

Scattering Properties of Large Irregular Cosmic Dust Particles at Visible Wavelengths

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

Escobar-Cerezo, J.; Palmer, C.; Muñoz, O.

The effect of internal inhomogeneities and surface roughness on the scattering behavior of large cosmic dust particles is studied by comparing model simulations with laboratory measurements. The present work shows the results of an attempt to model a dust sample measured in the laboratory with simulations performed by a ray-optics model code. We consider this dust sample as a good analogue for interplanetary and interstellar dust as it shares its refractive index with known materials in these media. Several sensitivity tests have been performed for both structural cases (internal inclusions and surface roughness). Three different samples have been selected tomore » mimic inclusion/coating inhomogeneities: two measured scattering matrices of hematite and white clay, and a simulated matrix for water ice. These three matrices are selected to cover a wide range of imaginary refractive indices. The selection of these materials also seeks to study astrophysical environments of interest such as Mars, where hematite and clays have been detected, and comets. Based on the results of the sensitivity tests shown in this work, we perform calculations for a size distribution of a silicate-type host particle model with inclusions and surface roughness to reproduce the experimental measurements of a dust sample. The model fits the measurements quite well, proving that surface roughness and internal structure play a role in the scattering pattern of irregular cosmic dust particles.« less

A label-free photoelectrochemical aptasensor for bisphenol A based on surface plasmon resonance of gold nanoparticle-sensitized ZnO nanopencils.

PubMed

Qiao, Yunfei; Li, Jing; Li, Hongbo; Fang, Hailin; Fan, Dahe; Wang, Wei

2016-12-15

A simple and novel photoelectrochemical (PEC) aptasensor for selective detection of bisphenol A (BPA) was developed using surface plasmon resonance of Au nanoparticles activated ZnO nanopencils. With the irradiation of simulated light, the increased photocurrent of nano-Au/ZnO than that of pure ZnO nanopencil is induced by the hot electrons from excited Au nanoparticles. The perfect selectivity is attributed to the specific binding of BPA to its aptamer. With the addition of BPA, the conformation of aptamer changed to a G-quadruplex structure, which resulted in the blockages of photogenerated electron-transfer channels. Based on the above mechanisms and the optimized conditions, the assembled PEC aptasensor was linear with the concentration of BPA in the range of 1-1000nmolL(-1) with a detection limit of 0.5nmolL(-1). The presence of the same concentration and similar structure of other organics did not interfere in the detection of BPA and the recovery was between 96.2% and 108.4%. It has been successfully applied to the detection of BPA in drinking water and liquid milk samples. This PEC aptasensor has good performances in novelty, selectivity, sensitivity and low cost, and it provides an alternative approach to the detection of BPA. Copyright © 2016 Elsevier B.V. All rights reserved.

Near-IR Two-Photon Fluorescent Sensor for K(+) Imaging in Live Cells.

PubMed

Sui, Binglin; Yue, Xiling; Kim, Bosung; Belfield, Kevin D

2015-08-19

A new two-photon excited fluorescent K(+) sensor is reported. The sensor comprises three moieties, a highly selective K(+) chelator as the K(+) recognition unit, a boron-dipyrromethene (BODIPY) derivative modified with phenylethynyl groups as the fluorophore, and two polyethylene glycol chains to afford water solubility. The sensor displays very high selectivity (>52-fold) in detecting K(+) over other physiological metal cations. Upon binding K(+), the sensor switches from nonfluorescent to highly fluorescent, emitting red to near-IR (NIR) fluorescence. The sensor exhibited a good two-photon absorption cross section, 500 GM at 940 nm. Moreover, it is not sensitive to pH in the physiological pH range. Time-dependent cell imaging studies via both one- and two-photon fluorescence microscopy demonstrate that the sensor is suitable for dynamic K(+) sensing in living cells.

Optimization of single photon detection model based on GM-APD

NASA Astrophysics Data System (ADS)

Chen, Yu; Yang, Yi; Hao, Peiyu

2017-11-01

One hundred kilometers high precision laser ranging hopes the detector has very strong detection ability for very weak light. At present, Geiger-Mode of Avalanche Photodiode has more use. It has high sensitivity and high photoelectric conversion efficiency. Selecting and designing the detector parameters according to the system index is of great importance to the improvement of photon detection efficiency. Design optimization requires a good model. In this paper, we research the existing Poisson distribution model, and consider the important detector parameters of dark count rate, dead time, quantum efficiency and so on. We improve the optimization of detection model, select the appropriate parameters to achieve optimal photon detection efficiency. The simulation is carried out by using Matlab and compared with the actual test results. The rationality of the model is verified. It has certain reference value in engineering applications.

Design, fabrication and characterization of an a-Si:H-based UV detector for sunburn applications

NASA Astrophysics Data System (ADS)

Bayat, Khadijeh; Vygranenko, Yuriy; Sazonov, Andrei; Farrokh-Baroughi, Mahdi

2006-12-01

A thin-film a-Si:H pin detector was developed for selective detection of UVA (320-400 nm) radiation. In order for the fabrication technology to be transferable onto flexible substrates, all of the processing steps were conducted at temperatures less than 125 °C. The measured saturation current as low as 2 pA cm-2 and the ideality factor of 1.47 show that the pin diodes have a good quality i-layer as well as p-i and n-i interfaces. The film thicknesses were optimized to suppress the detector sensitivity in the visible spectral range, and the peak of spectral response was observed at 410 nm. The selectivity estimated from the ratio of the photocurrent generated by UVA absorption to the total photocurrent is 21%.

Estimating skin sensitization potency from a single dose LLNA.

PubMed

Roberts, David W

2015-04-01

Skin sensitization is an important aspect of safety assessment. The mouse local lymph node assay (LLNA) developed in the 1990 s is an in vivo test used for skin sensitization hazard identification and characterization. More recently a reduced version of the LLNA (rLLNA) has been developed as a means of identifying, but not quantifying, sensitization hazard. The work presented here is aimed at enabling rLLNA data to be used to give quantitative potency information that can be used, inter alia, in modeling and read-across approaches to non-animal based potency estimation. A probit function has been derived enabling estimation of EC3 from a single dose. This has led to development of a modified version of the rLLNA, whereby as a general principle the SI value at 10%, or at a lower concentration if 10% is not testable, is used to calculate the EC3. This version of the rLLNA has been evaluated against a selection of chemicals for which full LLNA data are available, and has been shown to give EC3 values in good agreement with those derived from the full LLNA. Copyright © 2015 Elsevier Inc. All rights reserved.

Engineering the bioelectrochemical interface using functional nanomaterials and microchip technique toward sensitive and portable electrochemical biosensors.

PubMed

Jia, Xiaofang; Dong, Shaojun; Wang, Erkang

2016-02-15

Electrochemical biosensors have played active roles at the forefront of bioanalysis because they have the potential to achieve sensitive, specific and low-cost detection of biomolecules and many others. Engineering the electrochemical sensing interface with functional nanomaterials leads to novel electrochemical biosensors with improved performances in terms of sensitivity, selectivity, stability and simplicity. Functional nanomaterials possess good conductivity, catalytic activity, biocompatibility and high surface area. Coupled with bio-recognition elements, these features can amplify signal transduction and biorecognition events, resulting in highly sensitive biosensing. Additionally, microfluidic electrochemical biosensors have attracted considerable attention on account of their miniature, portable and low-cost systems as well as high fabrication throughput and ease of scaleup. For example, electrochemical enzymetic biosensors and aptamer biosensors (aptasensors) based on the integrated microchip can be used for portable point-of-care diagnostics and environmental monitoring. This review is a summary of our recent progress in the field of electrochemical biosensors, including aptasensors, cytosensors, enzymatic biosensors and self-powered biosensors based on biofuel cells. We presented the advantages that functional nanomaterials and microfluidic chip technology bring to the electrochemical biosensors, together with future prospects and possible challenges. Copyright © 2015 Elsevier B.V. All rights reserved.

A light-up probe targeting for Bcl-2 2345 G-quadruplex DNA with carbazole TO

NASA Astrophysics Data System (ADS)

Gu, Yingchun; Lin, Dayong; Tang, Yalin; Fei, Xuening; Wang, Cuihong; Zhang, Baolian; Zhou, Jianguo

2018-02-01

As its significant role, the selective recognition of G-quadruplex with specific structures and functions is important in biological and medicinal chemistry. Carbazole derivatives have been reported as a kind of fluorescent probe with many excellent optical properties. In the present study, the fluorescence of the dye (carbazole TO) increased almost 70 fold in the presence of bcl-2 2345 G4 compared to that alone in aqueous buffer condition with almost no fluorescence and 10-30 fold than those in the presence of other DNAs. The binding study results by activity inhibition of G4/Hemin peroxidase experiment, NMR titration and molecular docking simulation showed the high affinity and selectivity to bcl-2 2345 G4 arises from its end-stacking interaction with G-quartet. It is said that a facile approach with excellent sensitive, good selectivity and quick response for bcl-2 2345 G-quadruplex was developed and may be used for antitumor recognition or antitumor agents.

Formation of N, S-codoped fluorescent carbon dots from biomass and their application for the selective detection of mercury and iron ion

NASA Astrophysics Data System (ADS)

Ye, Qianghua; Yan, Fanyong; Luo, Yunmei; Wang, Yinyin; Zhou, Xuguang; Chen, Li

2017-02-01

Biomass is regarded as an excellent candidate for the preparation of heteroatom-doped carbon nanomaterials. We have developed a simple and facile one-pot synthesis of nitrogen and sulfur codoped fluorescent carbon dots from pigeon feathers, egg and manure via the pyrolysis carbonization method. The as-prepared four PCDs have high fluorescence quantum yield about 24.87% (PCDs-f), 17.48% (PCDs-w), 16.34% (PCDs-y), 33.50% (PCDs-m), respectively, which is higher than the other carbon dots preparing from biomass. We found that the preparation of PCDs-m with pigeon manure has no favourable selectively with heavy metal ions. However, other PCDs exhibit highly sensitive and selective detection behavior of Hg2 +/Fe3 + ions with a low detection limit of 10.3 and 60.9 nM. They were applied to imaging of human umbilical vein endothelial cells, showing low cytotoxicity and good biocompatibility.

Study of zeolite influence on analytical characteristics of urea biosensor based on ion-selective field-effect transistors

PubMed Central

2014-01-01

A possibility of the creation of potentiometric biosensor by adsorption of enzyme urease on zeolite was investigated. Several variants of zeolites (nano beta, calcinated nano beta, silicalite, and nano L) were chosen for experiments. The surface of pH-sensitive field-effect transistors was modified with particles of zeolites, and then the enzyme was adsorbed. As a control, we used the method of enzyme immobilization in glutaraldehyde vapour (without zeolites). It was shown that all used zeolites can serve as adsorbents (with different effectiveness). The biosensors obtained by urease adsorption on zeolites were characterized by good analytical parameters (signal reproducibility, linear range, detection limit and the minimal drift factor of a baseline). In this work, it was shown that modification of the surface of pH-sensitive field-effect transistors with zeolites can improve some characteristics of biosensors. PMID:24636423

Modeling the energy balance in Marseille: Sensitivity to roughness length parameterizations and thermal admittance

NASA Astrophysics Data System (ADS)

Demuzere, M.; De Ridder, K.; van Lipzig, N. P. M.

2008-08-01

During the ESCOMPTE campaign (Experience sur Site pour COntraindre les Modeles de Pollution atmospherique et de Transport d'Emissions), a 4-day intensive observation period was selected to evaluate the Advanced Regional Prediction System (ARPS), a nonhydrostatic meteorological mesoscale model that was optimized with a parameterization for thermal roughness length to better represent urban surfaces. The evaluation shows that the ARPS model is able to correctly reproduce temperature, wind speed, and direction for one urban and two rural measurements stations. Furthermore, simulated heat fluxes show good agreement compared to the observations, although simulated sensible heat fluxes were initially too low for the urban stations. In order to improve the latter, different roughness length parameterization schemes were tested, combined with various thermal admittance values. This sensitivity study showed that the Zilitinkevich scheme combined with and intermediate value of thermal admittance performs best.

Discrimination of selected species of pathogenic bacteria using near-infrared Raman spectroscopy and principal components analysis

NASA Astrophysics Data System (ADS)

de Siqueira e Oliveira, Fernanda S.; Giana, Hector E.; Silveira, Landulfo, Jr.

2012-03-01

It has been proposed a method based on Raman spectroscopy for identification of different microorganisms involved in bacterial urinary tract infections. Spectra were collected from different bacterial colonies (Gram negative: E. coli, K. pneumoniae, P. mirabilis, P. aeruginosa, E. cloacae and Gram positive: S. aureus and Enterococcus sp.), grown in culture medium (Agar), using a Raman spectrometer with a fiber Raman probe (830 nm). Colonies were scraped from Agar surface placed in an aluminum foil for Raman measurements. After pre-processing, spectra were submitted to a Principal Component Analysis and Mahalanobis distance (PCA/MD) discrimination algorithm. It has been found that the mean Raman spectra of different bacterial species show similar bands, being the S. aureus well characterized by strong bands related to carotenoids. PCA/MD could discriminate Gram positive bacteria with sensitivity and specificity of 100% and Gram negative bacteria with good sensitivity and high specificity.

Teaching transcultural nursing through literature.

PubMed

Halloran, Laurel

2009-09-01

One of the biggest challenges in nursing education is to develop culturally sensitive graduates. Although theory and lecture are appropriate to introduce cultural issues, the application of those skills is limited by the kinds of clinical experiences and patient populations students may treat. Literary works are a rich source of information for nursing. This assignment was created to sensitize the students to the influence of cultural diversity. Students were assigned to read one novel from an approved list and answer the questions posed on the Cultural Discovery worksheet. The only direction that was given regarding novel selection was that the novel had to represent a culture other than the student's own. The focus was to expose students to a different culture. Classroom discussion, based on worksheet answers, followed. The assignment's good, bad, and ugly outcomes are discussed. Suggestions for adaptation of this assignment to an online format are also provided.

Dielectric properties characterization of saline solutions by near-field microwave microscopy

NASA Astrophysics Data System (ADS)

Gu, Sijia; Lin, Tianjun; Lasri, Tuami

2017-01-01

Saline solutions are of a great interest when characterizations of biological fluids are targeted. In this work a near-field microwave microscope is proposed for the characterization of liquids. An interferometric technique is suggested to enhance measurement sensitivity and accuracy. The validation of the setup and the measurement technique is conducted through the characterization of a large range of saline concentrations (0-160 mg ml-1). Based on the measured resonance frequency shift and quality factor, the complex permittivity is successfully extracted as exhibited by the good agreement found when comparing the results to data obtained from Cole-Cole model. We demonstrate that the near field microwave microscope (NFMM) brings a great advantage by offering the possibility to select a resonance frequency and a quality factor for a given concentration level. This method provides a very effective way to largely enhance the measurement sensitivity in high loss materials.

Determination of amantadine and rimantadine using a sensitive fluorescent probe

NASA Astrophysics Data System (ADS)

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

2012-12-01

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

Monitoring of chlorsulfuron in biological fluids and water samples by molecular fluorescence using rhodamine B as fluorophore.

PubMed

Alesso, Magdalena; Escudero, Luis A; Talio, María Carolina; Fernández, Liliana P

2016-11-01

A new simple methodology is proposed for chlorsufuron (CS) traces quantification based upon enhancement of rhodamine B (RhB) fluorescent signal. Experimental variables that influence fluorimetric sensitivity have been studied and optimized. The zeroth order regression calibration was linear from 0.866 to 35.800µgL(-1) CS, with a correlation coefficient of 0.99. At optimal experimental conditions, a limit of detection of 0.259µgL(-1) and a limit of quantification of 0.866µgL(-1) were obtained. The method showed good sensitivity and adequate selectivity and was applied to the determination of trace amounts of CS in plasma, serum and water samples with satisfactory results analyzed by ANOVA test. The proposed methodology represents an alternative to traditional chromatographic techniques for CS monitoring in complex samples, using an accessible instrument in control laboratories. Copyright © 2016 Elsevier B.V. All rights reserved.

MRI-guided targeting delivery of doxorubicin with reduction-responsive lipid-polymer hybrid nanoparticles.

PubMed

Wu, Bo; Lu, Shu-Ting; Deng, Kai; Yu, Hui; Cui, Can; Zhang, Yang; Wu, Ming; Zhuo, Ren-Xi; Xu, Hai-Bo; Huang, Shi-Wen

2017-01-01

In recent years, there has been increasing interest in developing a multifunctional nanoscale platform for cancer monitoring and chemotherapy. However, there is still a big challenge for current clinic contrast agents to improve their poor tumor selectivity and response. Herein, we report a new kind of Gd complex and folate-coated redox-sensitive lipid-polymer hybrid nanoparticle (Gd-FLPNP) for tumor-targeted magnetic resonance imaging and therapy. Gd-FLPNPs can simultaneously accomplish diagnostic imaging, and specific targeting and controlled release of doxorubicin (DOX). They exhibit good monodispersity, excellent size stability, and a well-defined core-shell structure. Paramagnetic nanoparticles based on gadolinium-diethylenetriaminepentaacetic acid-bis-cetylamine have paramagnetic properties with an approximately two-fold enhancement in the longitudinal relaxivity compared to clinical used Magnevist. For targeted and reduction-sensitive drug delivery, Gd-FLPNPs released DOX faster and enhanced cell uptake in vitro, and exhibited better antitumor effect both in vitro and in vivo.

A novel alcohol dehydrogenase biosensor based on solid-state electrogenerated chemiluminescence by assembling dehydrogenase to Ru(bpy)(3)2+-Au nanoparticles aggregates.

PubMed

Zhang, Lihua; Xu, Zhiai; Sun, Xuping; Dong, Shaojun

2007-01-15

Based on electrogenerated chemiluminescence (ECL), a novel method for fabrication of alcohol dehydrogenase (ADH) biosensor by self-assembling ADH to Ru(bpy)(3)(2+)-AuNPs aggregates (Ru-AuNPs) on indium tin oxide (ITO) electrode surface has been developed. Positively charged Ru(bpy)(3)(2+) could be immobilized stably on the electrode surface with negatively charged AuNPs in the form of aggregate via electrostatic interaction. On the other hand, AuNPs are favourable candidates for the immobilization of enzymes because amine groups and cysteine residues in the enzymes are known to bind strongly with AuNPs. Moreover, AuNPs can act as tiny conduction centers to facilitate the transfer of electrons. Such biosensor combined enzymatic selectivity with the sensitivity of ECL detection for quantification of enzyme substrate, and it displayed wide linear range, high sensitivity and good stability.

Development of a high-sensitivity plasticizer sensor based on a quartz crystal microbalance modified with a nanostructured nickel hydroxide film

NASA Astrophysics Data System (ADS)

Hu, Ruifen; Zhang, Kaihuan; Fan, Guokang; Luo, Zhiyuan; Li, Guang

2015-05-01

Nanostructured nickel hydroxide (nano-Ni(OH)2) was synthesized at a low temperature without annealing. Accordingly, a plasticizer sensor based on a quartz crystal microbalance (QCM) modified with the nano-Ni(OH)2 sensing film was fabricated to detect dibutyl phthalate (DBP) and its relative film thickness was optimized. The sensor worked at room temperature and exhibited a high sensitivity of 4.91 Hz ppb-1 to DBP in a low concentration range of 5-20 ppb, and an ultra-low detection limit of 5 ppb was achieved. In addition, the sensor maintained good repeatability as well as stability shown by the experimental data. The responses to five possible interferences and four other plasticizers were also measured, which indicated the excellent selectivity of the sensor and its potential use in monitoring plasticizers in a gaseous state.

Planning Experiments for a Microgravity Environment

NASA Technical Reports Server (NTRS)

Rogers, Melissa J. B.

1998-01-01

Prior to performing science experiments in a microgravity environment, scientists must understand and appreciate a variety of issues related to that environment. The microgravity conditions required for optimum performance of the experiment will help define an appropriate carrier, drop facility, sounding rocket, free-flyer, or manned orbiting spacecraft. Within a given carrier, such as the International Space Station, experiment sensitivity to vibrations and quasi-steady accelerations should also influence the location and orientation of the experiment apparatus; the flight attitude of the carrier (if selectable); and the scheduling of experiment operations in conjunction with other activities. If acceptable microgravity conditions are not expected from available carriers or experiment scheduling cannot avoid disruptive activities, then a vibration isolation system should be considered. In order to best interpret the experimental results, appropriate accelerometer data must be collected contemporaneously with the experimental data. All of this requires a good understanding of experiment sensitivity to the microgravity environment.

Stable genetic structure and connectivity in pollution-adapted and nearby pollution-sensitive populations of Fundulus heteroclitus

PubMed Central

Biancani, Leann M.; Flight, Patrick A.; Nacci, Diane E.; Rand, David M.; Crawford, Douglas L.; Oleksiak, Marjorie F.

2018-01-01

Populations of the non-migratory estuarine fish Fundulus heteroclitus inhabiting the heavily polluted New Bedford Harbour (NBH) estuary have shown inherited tolerance to local pollutants introduced to their habitats in the past 100 years. Here we examine two questions: (i) Is there pollution-driven selection on the mitochondrial genome across a fine geographical scale? and (ii) What is the pattern of migration among sites spanning a strong pollution gradient? Whole mitochondrial genomes were analysed for 133 F. heteroclitus from seven nearby collection sites: four sites along the NBH pollution cline (approx. 5 km distance), which had pollution-adapted fish, as well as one site adjacent to the pollution cline and two relatively unpolluted sites about 30 km away, which had pollution-sensitive fish. Additionally, we used microsatellite analyses to quantify genetic variation over three F. heteroclitus generations in both pollution-adapted and sensitive individuals collected from two sites at two different time points (1999/2000 and 2007/2008). Our results show no evidence for a selective sweep of mtDNA in the polluted sites. Moreover, mtDNA analyses revealed that both pollution-adapted and sensitive populations harbour similar levels of genetic diversity. We observed a high level of non-synonymous mutations in the most polluted site. This is probably associated with a reduction in Ne and concomitant weakening of purifying selection, a demographic expansion following a pollution-related bottleneck or increased mutation rates. Our demographic analyses suggest that isolation by distance influences the distribution of mtDNA genetic variation between the pollution cline and the clean populations at broad spatial scales. At finer scales, population structure is patchy, and neither spatial distance, pollution concentration or pollution tolerance is a good predictor of mtDNA variation. Lastly, microsatellite analyses revealed stable population structure over the last decade. PMID:29892357

Highly sensitive copper fiber-in-tube solid-phase microextraction for online selective analysis of polycyclic aromatic hydrocarbons coupled with high performance liquid chromatography.

PubMed

Sun, Min; Feng, Juanjuan; Bu, Yanan; Luo, Chuannan

2015-08-21

A fiber-in-tube solid-phase microextraction (SPME) device was developed with copper wire and copper tube, which was served as both the substrate and sorbent with high physical strength and good flexibility. Its morphology and surface properties were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. It was coupled with high performance liquid chromatography (HPLC) equipment by replacing the sample loop of six-port injection valve, building the online SPME-HPLC system conveniently. Using ten polycyclic aromatic hydrocarbons (PAHs) as model analytes, extraction conditions including sampling rate, extraction time, organic content and desorption time were investigated and optimized. The copper fiber-in-tube exhibits excellent extraction efficiency toward PAHs, with enrichment factors from 268 to 2497. The established online SPME-HPLC method provides good linearity (0.05-100μgL(-1)) and low detection limits (0.001-0.01μgL(-1)) for PAHs. It has been used to determine PAHs in water samples, with recoveries in the range of 86.2-115%. Repeatability on the same extraction tube is in the range of 0.6-3.6%, and repeatability among three tubes is in the range of 5.6-20.1%. Compared with phthalates, anilines and phenols, the copper fiber-in-tube possesses good extraction selectivity for PAHs. The extraction mechanism is probably related to hydrophobic interaction and π-electron-metal interaction. Copyright © 2015 Elsevier B.V. All rights reserved.

Decision analysis for a data collection system of patient-controlled analgesia with a multi-attribute utility model.

PubMed

Lee, I-Jung; Huang, Shih-Yu; Tsou, Mei-Yung; Chan, Kwok-Hon; Chang, Kuang-Yi

2010-10-01

Data collection systems are very important for the practice of patient-controlled analgesia (PCA). This study aimed to evaluate 3 PCA data collection systems and selected the most favorable system with the aid of multiattribute utility (MAU) theory. We developed a questionnaire with 10 items to evaluate the PCA data collection system and 1 item for overall satisfaction based on MAU theory. Three systems were compared in the questionnaire, including a paper record, optic card reader and personal digital assistant (PDA). A pilot study demonstrated a good internal and test-retest reliability of the questionnaire. A weighted utility score combining the relative importance of individual items assigned by each participant and their responses to each question was calculated for each system. Sensitivity analyses with distinct weighting protocols were conducted to evaluate the stability of the final results. Thirty potential users of a PCA data collection system were recruited in the study. The item "easy to use" had the highest median rank and received the heaviest mean weight among all items. MAU analysis showed that the PDA system had a higher utility score than that in the other 2 systems. Sensitivity analyses revealed that both inverse and reciprocal weighting processes favored the PDA system. High correlations between overall satisfaction and MAU scores from miscellaneous weighting protocols suggested a good predictive validity of our MAU-based questionnaire. The PDA system was selected as the most favorable PCA data collection system by the MAU analysis. The item "easy to use" was the most important attribute of the PCA data collection system. MAU theory can evaluate alternatives by taking into account individual preferences of stakeholders and aid in better decision-making. Copyright © 2010 Elsevier. Published by Elsevier B.V. All rights reserved.

Hotspots engineering by grafting Au@Ag core-shell nanoparticles on the Au film over slightly etched nanoparticles substrate for on-site paraquat sensing.

PubMed

Wang, Chaoguang; Wu, Xuezhong; Dong, Peitao; Chen, Jian; Xiao, Rui

2016-12-15

Paraquat (PQ) pollutions are ultra-toxic to human beings and hard to be decomposed in the environment, thus requiring an on-site detection strategy. Herein, we developed a robust and rapid PQ sensing strategy based on the surface-enhanced Raman scattering (SERS) technique. A hybrid SERS substrate was prepared by grafting the Au@Ag core-shell nanoparticles (NPs) on the Au film over slightly etched nanoparticles (Au FOSEN). Hotspots were engineered at the junctions as indicated by the finite difference time domain calculation. SERS performance of the hybrid substrate was explored using p-ATP as the Raman probe. The hybrid substrate gives higher enhancement factor comparing to either the Au FOSEN substrate or the Au@Ag core-shell NPs, and exhibits excellent reproducibility, homogeneity and stability. The proposed SERS substrates were prepared in batches for the practical PQ sensing. The total analysis time for a single sample, including the pre-treatment and measurement, was less than 5min with a PQ detection limit of 10nM. Peak intensities of the SERS signal were plotted as a function of the PQ concentrations to calibrate the sensitivity by fitting the Hill's equation. The plotted calibration curve showed a good log-log linearity with the coefficient of determination of 0.98. The selectivity of the sensing proposal was based on the "finger print" Raman spectra of the analyte. The proposed substrate exhibited good recovery when it applied to real water samples, including lab tap water, bottled water, and commercially obtained apple juice and grape juice. This SERS-based PQ detection method is simple, rapid, sensitive and selective, which shows great potential in pesticide residue and additives abuse monitoring. Copyright © 2016 Elsevier B.V. All rights reserved.

Detection of Organophosphorus Pesticides with Colorimetry and Computer Image Analysis.

PubMed

Li, Yanjie; Hou, Changjun; Lei, Jincan; Deng, Bo; Huang, Jing; Yang, Mei

2016-01-01

Organophosphorus pesticides (OPs) represent a very important class of pesticides that are widely used in agriculture because of their relatively high-performance and moderate environmental persistence, hence the sensitive and specific detection of OPs is highly significant. Based on the inhibitory effect of acetylcholinesterase (AChE) induced by inhibitors, including OPs and carbamates, a colorimetric analysis was used for detection of OPs with computer image analysis of color density in CMYK (cyan, magenta, yellow and black) color space and non-linear modeling. The results showed that there was a gradually weakened trend of yellow intensity with the increase of the concentration of dichlorvos. The quantitative analysis of dichlorvos was achieved by Artificial Neural Network (ANN) modeling, and the results showed that the established model had a good predictive ability between training sets and predictive sets. Real cabbage samples containing dichlorvos were detected by colorimetry and gas chromatography (GC), respectively. The results showed that there was no significant difference between colorimetry and GC (P > 0.05). The experiments of accuracy, precision and repeatability revealed good performance for detection of OPs. AChE can also be inhibited by carbamates, and therefore this method has potential applications in real samples for OPs and carbamates because of high selectivity and sensitivity.

The Development of Non-Enzymatic Glucose Biosensors Based on Electrochemically Prepared Polypyrrole-Chitosan-Titanium Dioxide Nanocomposite Films.

PubMed

Al-Mokaram, Ali M A Abdul Amir; Yahya, Rosiyah; Abdi, Mahnaz M; Mahmud, Habibun Nabi Muhammad Ekramul

2017-05-31

The performance of a modified electrode of nanocomposite films consisting of polypyrrole-chitosan-titanium dioxide (Ppy-CS-TiO₂) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO₂ nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO₂ NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO₂ in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1-14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO₂ nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell.

Reusable and Mediator-Free Cholesterol Biosensor Based on Cholesterol Oxidase Immobilized onto TGA-SAM Modified Smart Bio-Chips

PubMed Central

Rahman, Mohammed M.

2014-01-01

A reusable and mediator-free cholesterol biosensor based on cholesterol oxidase (ChOx) was fabricated based on self-assembled monolayer (SAM) of thioglycolic acid (TGA) (covalent enzyme immobilization by dropping method) using bio-chips. Cholesterol was detected with modified bio-chip (Gold/Thioglycolic-acid/Cholesterol-oxidase i.e., Au/TGA/ChOx) by reliable cyclic voltammetric (CV) technique at room conditions. The Au/TGA/ChOx modified bio-chip sensor demonstrates good linearity (1.0 nM to 1.0 mM; R = 0.9935), low-detection limit (∼0.42 nM, SNR∼3), and higher sensitivity (∼74.3 µAµM−1cm−2), lowest-small sample volume (50.0 μL), good stability, and reproducibility. To the best of our knowledge, this is the first statement with a very high sensitivity, low-detection limit, and low-sample volumes are required for cholesterol biosensor using Au/TGA/ChOx-chips assembly. The result of this facile approach was investigated for the biomedical applications for real samples at room conditions with significant assembly (Au/TGA/ChOx) towards the development of selected cholesterol biosensors, which can offer analytical access to a large group of enzymes for wide range of biomedical applications in health-care fields. PMID:24949733

Comparison of the Diagnostic Accuracy of Three Rapid Tests for the Serodiagnosis of Hepatic Cystic Echinococcosis in Humans

PubMed Central

Tamarozzi, Francesca; Covini, Ilaria; Mariconti, Mara; Narra, Roberta; Tinelli, Carmine; De Silvestri, Annalisa; Manzoni, Federica; Casulli, Adriano; Ito, Akira; Neumayr, Andreas; Brunetti, Enrico

2016-01-01

Background The diagnosis of cystic echinococcosis (CE) is based primarily on imaging, in particular with ultrasound for abdominal CE, complemented by serology when imaging results are unclear. In rural endemic areas, where expertise in ultrasound may be scant and conventional serology techniques are unavailable due to lack of laboratory equipment, Rapid Diagnostic Tests (RDTs) are appealing. Methodology/Principal Findings We evaluated the diagnostic accuracy of 3 commercial RDTs for the diagnosis of hepatic CE. Sera from 59 patients with single hepatic CE cysts in well-defined ultrasound stages (gold standard) and 25 patients with non-parasitic cysts were analyzed by RDTs VIRapid HYDATIDOSIS (Vircell, Spain), Echinococcus DIGFA (Unibiotest, China), ADAMU-CE (ICST, Japan), and by RIDASCREEN Echinococcus IgG ELISA (R-Biopharm, Germany). Sensitivity, specificity and ROC curves were compared with McNemar and t-test. For VIRapid and DIGFA, correlation between semiquantitative results and ELISA OD values were evaluated by Spearman’s coefficient. Reproducibility was assessed on 16 randomly selected sera with Cohen’s Kappa coefficient. Sensitivity and Specificity of VIRapid (74%, 96%) and ADAMU-CE (57%, 100%) did not differ from ELISA (69%, 96%) while DIGFA (72%, 72%) did (p = 0.045). ADAMU-CE was significantly less sensitive in the diagnosis of active cysts (p = 0.019) while DIGFA was significantly less specific (p = 0.014) compared to ELISA. All tests were poorly sensitive in diagnosing inactive cysts (33.3% ELISA and ADAMU-CE, 42.8% DIGFA, 47.6% VIRapid). The reproducibility of all RDTs was good-very good. Band intensity of VIRapid and DIGFA correlated with ELISA OD values (r = 0.76 and r = 0.79 respectively, p<0.001). Conclusions/Significance RDTs may be useful in resource-poor settings to complement ultrasound diagnosis of CE in uncertain cases. VIRapid test appears to perform best among the examined kits, but all tests are poorly sensitive in the presence of inactive cysts, which may pose problems with accurate diagnosis. PMID:26871432

The relationship between ischaemia-modified albumin and good coronary collateral circulation.

PubMed

Gök, Murat; Kundi, Harun; Kızıltunç, Emrullah; Topcuoglu, Canan; Ornek, Ender

2018-01-01

It is important to determine the grade of the coronary collateral circulation (CCC) in patients with stable coronary artery disease. In this study, we aimed to investigate the relationship between the ischaemia-modified albumin (IMA) level and good CCC. A total of 95 patients with coronary angiography and at least one epicardial coronary artery obstruction were included in the study. The Rentrop classification was used with CCC grading, where 0 and 1 were defined as poor collateral, and 2 and 3 were defined as good collateral. The IMA level of the patients was measured using an enzyme-linked immunosorbent assay (ELISA). The receiver-operating characteristic curve was used to show the sensitivity and specificity of IMA levels and the optimal cut-off value for predicting good CCC. The multiple logistic regression analysis revealed that the IMA level in the good CCC group was higher (p < 0.045). Conversely, the high-sensitivity C-reactive protein level was lower in the good CCC group (p < 0.023). We found an IMA cut-off value (4.7 ng/mL) that indicated good CCC level, and this shows good CCC with 70.2% sensitivity and 60.3% specificity. The IMA level could serve as a simple and useful predictor of well-developed CCC.

Evaluation of antitumor activity and cardiac toxicity of a bone-targeted ph-sensitive liposomal formulation in a bone metastasis tumor model in mice.

PubMed

Dos Santos Ferreira, Diego; Jesus de Oliveira Pinto, Bruno Luís; Kumar, Vidhya; Cardoso, Valbert Nascimento; Fernandes, Simone Odília; Souza, Cristina Maria; Cassali, Geovanni Dantas; Moore, Anna; Sosnovik, David E; Farrar, Christian T; Leite, Elaine Amaral; Alves, Ricardo José; de Oliveira, Mônica Cristina; Guimarães, Alexander Ramos; Caravan, Peter

2017-07-01

Chemotherapy for bone tumors is a major challenge because of the inability of therapeutics to penetrate dense bone mineral. We hypothesize that a nanostructured formulation with high affinity for bone could deliver drug to the tumor while minimizing off-target toxicity. Here, we evaluated the efficacy and toxicity of a novel bone-targeted, pH-sensitive liposomal formulation containing doxorubicin in an animal model of bone metastasis. Biodistribution studies with the liposome showed good uptake in tumor, but low accumulation of doxorubicin in the heart. Mice treated with the bone-targeted liposome formulation showed a 70% reduction in tumor volume, compared to 35% reduction for free doxorubicin at the same dose. Both cardiac toxicity and overall mortality were significantly lower for animals treated with the bone-targeted liposomes compared to free drug. Bone-targeted, pH-sensitive, doxorubicin containing liposomes represent a promising approach to selectively delivering doxorubicin to bone tumors while minimizing cardiac toxicity. Copyright © 2017 Elsevier Inc. All rights reserved.

Common SphinX and RHESSI observations of solar flares

NASA Astrophysics Data System (ADS)

Mrozek, T.; Gburek, S.; Siarkowski, M.; Sylwester, B.; Sylwester, J.; Gryciuk, M.

The Polish X-ray spectrofotometer SphinX has observed a great number of solar flares in the year 2009 - during the most quiet solar minimum almost over the last 100 years. Hundreds of flares have been recorded due to excellent sensitivity of SphinX's detectors. The Si-PIN diodes are about 100 times more sensitive to X-rays than GOES X-ray Monitors. SphinX detectors were absolutely calibrated on Earth with a use of the BESSY synchrotron. In space observations were made in the range 1.2-15~keV with 480~eV energy resolution. SphinX data overlap with the low-energy end of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) data. RHESSI detectors are quite old (7 years in 2009), but still sensitive enough to provide us with observations of extremely weak solar flares such as those which occurred in 2009. We have selected a group of flares simultaneously observed by RHESSI and SphinX and performed a spectroscopic analysis of the data. Moreover, we compared the physical parameters of these flares plasma. Preliminary results of the comparison show very good agreement between both instruments.

The detection of formaldehyde using microelectromechanical acoustic resonator with multiwalled carbon nanotubes-polyethyleneimine composite coating

NASA Astrophysics Data System (ADS)

Wang, Jingjing; Zhan, Da; Wang, Ke; Hang, Weiwei

2018-01-01

A micro-scale gas sensor based on mass-sensitive film bulk acoustic resonator is demonstrated for the detection of trace formaldehyde at room temperature. The composites mixed with multiwalled carbon nanotubes and polyethyleneimine (MWNTs-PEI) were coated on the resonator surface as the sensitive layer to specifically absorb formaldehyde molecules using a facile spray process. The influence of spraying processes on the formaldehyde sensing properties were investigated. Different response behaviors were determined by both the chemical absorption between formaldehyde molecules and the amine functional groups on PEI and the increase of absorption surface came from the nanostructure. The combination of high frequency of the film bulk acoustic resonator (~4.3 GHz) and the specific absorbability of MWNTs-PEI composites provided a high sensitivity in the detections of trace formaldehyde. The obtained ultra-low limit of detection was as low as 60 ppb with linear response, quick response/recovery time, good reproducibility and selectivity. The proposed sensor shows potential as a portable and convenient gas-sensing system for monitoring the low-level concentration of indoor air pollution.

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

PubMed Central

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

2016-01-01

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

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

PubMed

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

2016-01-08

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

Accuracy of routine magnetic resonance imaging in meniscal and ligamentous injuries of the knee: comparison with arthroscopy

PubMed Central

Behairy, Noha H.; Dorgham, Mohsen A.

2008-01-01

The aim of this study was to detect the accuracy of routine magnetic resonance imaging (MRI) done in different centres and its agreement with arthroscopy in meniscal and ligamentous injuries of the knee. We prospectively examined 70 patients ranging in age between 22 and 59 years. History taking, plain X-ray, clinical examination, routine MRI and arthroscopy were done for all patients. Sensitivity, specificity, accuracy, positive and negative predictive values, P value and kappa agreement measures were calculated. We found a sensitivity of 47 and 100%, specificity of 95 and 75% and accuracy of 73 and 78.5%, respectively, for the medial and lateral meniscus. A sensitivity of 77.8%, specificity of 100% and accuracy of 94% was noted for the anterior cruciate ligament (ACL). We found good kappa agreements (0.43 and 0.45) for both menisci and excellent agreement (0.84) for the ACL. MRI shows high accuracy and should be used as the primary diagnostic tool for selection of candidates for arthroscopy. Level of evidence: 4. PMID:18506445

Fluorescence Polarization Immunoassay Based on a New Monoclonal Antibody for the Detection of the Zearalenone Class of Mycotoxins in Maize.

PubMed

Zhang, Xiya; Eremin, Sergei A; Wen, Kai; Yu, Xuezhi; Li, Chenglong; Ke, Yuebin; Jiang, Haiyang; Shen, Jianzhong; Wang, Zhanhui

2017-03-15

To develop a sensitive fluorescence polarization immunoassay (FPIA) for screening the zearalenone class of mycotoxins in maize, two new monoclonal antibodies with uniform affinity to the zearalenone class and four fluorescein-labeled tracers were prepared. After careful selection of appropriate tracer-antibody pairs in terms of sensitivity and specificity, a FPIA that could simultaneously detect the zearalenone class with similar sensitivity was developed. Under optimum conditions, the half maximal inhibitory concentrations of the FPIA in buffer were 1.89, 1.97, 2.43, 1.99, 2.27, and 2.44 μg/L for zearalenone, α-zearalenol, β-zearalenol, α-zearalanol, β-zearalanol, and zearalanone, respectively. The limit of detection of FPIA for the zearalenone class was around 12 μg/kg in maize, and the recoveries ranged from 84.6 to 113.8%, with coefficients of variation below 15.3% in spiked samples. Finally, the FPIA was applied for screening naturally contaminated maize samples, and the results indicated a good correlation with that of high-performance liquid chromatography-tandem mass spectrometry.

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

PubMed

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

2018-04-01

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

Single-course specific immunotherapy with mixed pollen allergoids: results of a multi-centre study.

PubMed

Drachenberg, K J; Pröll, S; Urban, E; Woroniecki, S R

2003-01-01

A short-term immunotherapy vaccine for the treatment of pollen allergy has been developed utilising L-tyrosine adsorbed allergoids. The reduced number of injections could provide advantages over long-term therapy schedules. This would improve compliance and support application of specific immunotherapy (SIT) to a greater extent. We report a multicenter study to evaluate the efficacy and safety of this treatment in a clinical practice setting. Patients (n = 1808) with a diagnosis of sensitivities to various pollens and symptoms of allergic asthma and/or allergic rhinitis and/or allergic conjunctivitis were selected. The vaccine formulation was made up according to individual sensitivities and contained L-tyrosine adsorbed allergoids. The patients were treated with a 3-injection initial course followed by a 3-injection maintenance course. Efficacy was measured by consumption of symptomatic anti-allergic medication compared with that in the previous season and by physician assessment using a 5-point scale. All adverse events were recorded. Efficacy was demonstrated by a considerable decrease in regular and frequent use of medication compared with that in the previous season (p < 0.001). In addition, in 80 % of the patients, the physician's assessment was either "good" or "very good". These outcomes were unaffected by the closeness of the treatment course to the onset of the pollen season. Tolerability was good and most local and systemic reactions were mild. The treatment of pollen-allergic patients with a short-term SIT using a 6-injection pollen allergoid/L-tyrosine vaccine in a clinical practice setting provided a high level of efficacy with a low incidence of mainly mild adverse events.

Mendelian randomization with fine-mapped genetic data: Choosing from large numbers of correlated instrumental variables.

PubMed

Burgess, Stephen; Zuber, Verena; Valdes-Marquez, Elsa; Sun, Benjamin B; Hopewell, Jemma C

2017-12-01

Mendelian randomization uses genetic variants to make causal inferences about the effect of a risk factor on an outcome. With fine-mapped genetic data, there may be hundreds of genetic variants in a single gene region any of which could be used to assess this causal relationship. However, using too many genetic variants in the analysis can lead to spurious estimates and inflated Type 1 error rates. But if only a few genetic variants are used, then the majority of the data is ignored and estimates are highly sensitive to the particular choice of variants. We propose an approach based on summarized data only (genetic association and correlation estimates) that uses principal components analysis to form instruments. This approach has desirable theoretical properties: it takes the totality of data into account and does not suffer from numerical instabilities. It also has good properties in simulation studies: it is not particularly sensitive to varying the genetic variants included in the analysis or the genetic correlation matrix, and it does not have greatly inflated Type 1 error rates. Overall, the method gives estimates that are less precise than those from variable selection approaches (such as using a conditional analysis or pruning approach to select variants), but are more robust to seemingly arbitrary choices in the variable selection step. Methods are illustrated by an example using genetic associations with testosterone for 320 genetic variants to assess the effect of sex hormone related pathways on coronary artery disease risk, in which variable selection approaches give inconsistent inferences. © 2017 The Authors Genetic Epidemiology Published by Wiley Periodicals, Inc.

Gas chromatography and ultra high performance liquid chromatography tandem mass spectrometry methods for the determination of selected endocrine disrupting chemicals in human breast milk after stir-bar sorptive extraction.

PubMed

Rodríguez-Gómez, R; Zafra-Gómez, A; Camino-Sánchez, F J; Ballesteros, O; Navalón, A

2014-07-04

In the present work, two specific, accurate and sensitive methods for the determination of endocrine disrupting chemicals (EDCs) in human breast milk are developed and validated. Bisphenol A and its main chlorinated derivatives, five benzophenone-UV filters and four parabens were selected as target analytes. The method involves a stir-bar sorptive extraction (SBSE) procedure followed by a solvent desorption prior to GC-MS/MS or UHPLC-MS/MS analysis. A derivatization step is also necessary when GC analysis is performed. The GC column used was a capillary HP-5MS with a run time of 26min. For UHPLC analysis, the stationary phase was a non-polar Acquity UPLC(®) BEH C18 column and the run time was 10min. In both cases, the analytes were detected and quantified using a triple quadrupole mass spectrometer (QqQ). Quality parameters such as linearity, accuracy (trueness and precision), sensitivity and selectivity were examined and yielded good results. The limits of quantification (LOQs) ranged from 0.3 to 5.0ngmL(-1) for GC and from 0.2 to 1.0ngmL(-1) for LC. The relative standard deviation (RSD) was lower than 15% and the recoveries ranged from 92 to 114% in all cases, being slightly unfavorable the results obtained with LC. The methods were satisfactorily applied for the determination of target compounds in human milk samples from 10 randomly selected women. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis of functional carbon nanospheres by a composite-molten-salt method and amperometric sensing of hydrogen peroxide.

PubMed

Wang, Xue; Hu, Chenguo; Xiong, Yufeng; Zhang, Cuiling

2013-02-01

Functional carbon nanospheres have been synthesized from analytically pure glucose by a composite-molten-salt (CMS) method. Field emission scanning electron microscopy, transmission electron microscopy, Raman and Fourier transformation infra-red spectroscopy indicate the carbon nanospheres are solid, bond hybridisation (sp2/sp3) and with many functional groups on their surfaces. Amperometric sensor based on the synthesized carbon nanospheres have been fabricated without pretreatment or modification. The detection of hydrogen peroxide exhibits high sensitivity and good selectivity. The electrochemical measurement of these nanospheres demonstrates much superior performance to those of the carbon nanospheres synthesized by hydrothermal method.

Zinc sulfide quantum dots for photocatalytic and sensing applications

NASA Astrophysics Data System (ADS)

Sergeev, Alexander A.; Leonov, Andrei A.; Zhuikova, Elena I.; Postnova, Irina V.; Voznesenskiy, Sergey S.

2017-09-01

Herein, we report the photocatalytic and sensing applications of pure and Mn-doped ZnS quantum dots. The quantum dots were prepared by a chemical precipitation in an aqueous solution in the presence of glutathione as a stabilizing agent. The synthesized quantum dots were used as effective photocatalyst for the degradation of methylene blue dye. Interestingly, fully degradation of methylene blue dye was achieved in 5 min using pure ZnS quantum dots. Further, the synthesized quantum dots were used as efficient sensing element for methane fluorescent sensor. Interfering studies confirmed that the developed sensor possesses very good sensitivity and selectivity towards methane.

Continuous subcutaneous infusion in palliative care: a review of current practice.

PubMed

Thomas, Tabitha; Barclay, Stephen

2015-02-01

Syringe drivers are widely used in palliative care, and this article reviews the challenges and outstanding questions associated with their use. Misperceptions among the lay public and some health professionals can be addressed by sensitive communication with patients and families and clear thinking in clinical teams concerning the drugs and doses used, particularly in non-malignant disease. Good levels of knowledge concerning syringe driver use has been found among GPs and community nurses, although this is not the case in some nursing home teams. The advantages of newer devices, safety and efficacy of drug combinations, selection of diluent, and management of site reactions are discussed.

Expeditious microwave-assisted synthesis of 5-alkoxyoxazoles from α-triflyloxy esters and nitriles.

PubMed

Jouanno, Laurie-Anne; Sabot, Cyrille; Renard, Pierre-Yves

2012-10-05

A rapid and general access to diversely substituted 5-alkoxyoxazoles 2 (i.e., R(1), R(2) = alkyl, phenyl) from easily accessible α-triflyloxy/hydroxy esters 1 and nitriles with good yields (41-76%) is reported. The versatility of the cyclization is shown for a range of substrates with high selectivity toward triflates over mesylates and proved to be compatible with sensitive functional groups. As an illustration of this transformation, the first synthesis of the recently isolated hydroxypyridine methyl multijuguinate 4 was achieved in four steps through a hetero Diels-Alder reaction of the 5-alkoxyoxazole and acrylic acid, followed by a protodecarboxylation reaction.

Highly-sensitive microRNA detection based on bio-bar-code assay and catalytic hairpin assembly two-stage amplification.

PubMed

Tang, Songsong; Gu, Yuan; Lu, Huiting; Dong, Haifeng; Zhang, Kai; Dai, Wenhao; Meng, Xiangdan; Yang, Fan; Zhang, Xueji

2018-04-03

Herein, a highly-sensitive microRNA (miRNA) detection strategy was developed by combining bio-bar-code assay (BBA) with catalytic hairpin assembly (CHA). In the proposed system, two nanoprobes of magnetic nanoparticles functionalized with DNA probes (MNPs-DNA) and gold nanoparticles with numerous barcode DNA (AuNPs-DNA) were designed. In the presence of target miRNA, the MNP-DNA and AuNP-DNA hybridized with target miRNA to form a "sandwich" structure. After "sandwich" structures were separated from the solution by the magnetic field and dehybridized by high temperature, the barcode DNA sequences were released by dissolving AuNPs. The released barcode DNA sequences triggered the toehold strand displacement assembly of two hairpin probes, leading to recycle of barcode DNA sequences and producing numerous fluorescent CHA products for miRNA detection. Under the optimal experimental conditions, the proposed two-stage amplification system could sensitively detect target miRNA ranging from 10 pM to 10 aM with a limit of detection (LOD) down to 97.9 zM. It displayed good capability to discriminate single base and three bases mismatch due to the unique sandwich structure. Notably, it presented good feasibility for selective multiplexed detection of various combinations of synthetic miRNA sequences and miRNAs extracted from different cell lysates, which were in agreement with the traditional polymerase chain reaction analysis. The two-stage amplification strategy may be significant implication in the biological detection and clinical diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Towards field detection of polycyclic aromatic hydrocarbons (PAHs) in environment water using a self-assembled SERS sensor

NASA Astrophysics Data System (ADS)

Yan, Xia; Shi, Xiaofeng; Yang, Jie; Zhang, Xu; Jia, Wenjie; Ma, Jun

2017-10-01

A self-assembled surface enhanced Raman scattering (SERS) sensor is reported in this paper. To achieve high sensitivity, a high sensitive SERS substrate and a high efficient self-constructed light path were made. The SERS substrate was composed by gold nanoparticles (AuNPs, pH=13), glycidyl methacrylate-ethylene dimethacrylate (GMA-EDMA) porous material and syringe filter. The substrate had a good repeatability, and the relative standard deviation (RSD) of the same substrate was less than 5%. The efficiency of the self-constructed light path is about two times better than RPB Y type reflection fiber when the energy density was roughly equal on samples. The size of the SERS sensor is 350×300×180 mm and the weight is 15 kg. Its miniaturization and portable can comply with the requirements of field detection. Besides, it has good sensitivity, stability and selectivity. For lab experiments, strong enhancements of Raman scattering from organic pollutant polycyclic aromatic hydrocarbons (PAHs) molecules were exhibited. The dependences of SERS intensities on concentrations of PAHs were investigated, and the results indicated that they revealed a satisfactory linear relationship in low concentrations. The limits of detection (LODs) of PAHs phenanthrene and fluorene are 8.3×10-10 mol/L and 7.1×10-10 mol/L respectively [signal to noise ratio (S/N) =3]. Based on this SERS sensor, signals of benzo (a) pyrene and pyrene were found in environmental water and the sensor would be an ideal candidate for field detection of PAHs.

A nanocomposite optosensor containing carboxylic functionalized multiwall carbon nanotubes and quantum dots incorporated into a molecularly imprinted polymer for highly selective and sensitive detection of ciprofloxacin.

PubMed

Yuphintharakun, Naphat; Nurerk, Piyaluk; Chullasat, Kochaporn; Kanatharana, Proespichaya; Davis, Frank; Sooksawat, Dhassida; Bunkoed, Opas

2018-08-05

A nanocomposite optosensor consisting of carboxylic acid functionalized multiwall carbon nanotubes and CdTe quantum dots embedded inside a molecularly imprinted polymer (COOH@MWCNT-MIP-QDs) was developed for trace ciprofloxacin detection. The COOH@MWCNT-MIP-QDs were synthesized through a facile sol-gel process using ciprofloxacin as a template molecule, 3-aminopropylethoxysilane as a functional monomer and tetraethoxysilane as a cross-linker at a molar ratio of 1:8:20. The synthesized nanocomposite optosensor had high sensitivity, excellent specificity and high binding affinity to ciprofloxacin. Under optimal conditions, the fluorescence intensity of the optosensor decreased in a linear fashion with the concentration of ciprofloxacin and two linear dynamic ranges were obtained, 0.10-1.0 μg L -1 and 1.0-100.0 μg L -1 with a very low limit of detection of 0.066 μg L -1 . The imprinting factors of the two linear range were 17.67 and 4.28, respectively. The developed nanocomposite fluorescence probe was applied towards the determination of ciprofloxacin levels in chicken muscle and milk samples with satisfactory recoveries being obtained in the range of 82.6 to 98.4%. The results were also in good agreement with a HPLC method which indicates that the optosensor can be used as a sensitive, selective and rapid method to detect ciprofloxacin in chicken and milk samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Hydrochemical variations in selected geothermal groundwater and carbonated springs in Korea: a baseline study for early detection of CO2 leakage.

PubMed

Choi, Hanna; Piao, Jize; Woo, Nam C; Cho, Heuynam

2017-02-01

A baseline hydrochemistry of the above zone aquifer was examined for the potential of CO 2 early detection monitoring. Among the major ionic components and stable isotope ratios of oxygen, hydrogen, and carbon, components with a relative standard deviation (RSD) of <10 % for the seasonal variation were selected as relatively stable. These components were tested for sensitivity to the introduction of 0.1 mol/L CO 2 (g) using the PHREEQC simulation results. If the relatively stable components were sensitive to the introduction of CO 2 , then they could be used as indicators of CO 2 leakage into the above zone. As an analog to the zone above CO 2 storage formation, we sampled deep groundwater, including geothermal groundwater from well depths of 400-700 m below the ground surface (bgs) and carbonated springs with a high CO 2 content in Korea. Under the natural conditions of inland geothermal groundwater, pH, electrical conductivity (EC), bicarbonate (HCO 3 ), δ 18 O, δ 2 H, and δ 13 C were relatively stable as well as sensitive to the introduction of CO 2 (g), thus showing good potential as monitoring parameters for early detection of CO 2 leakage. In carbonated springs, the parameters identified were pH, δ 18 O, and δ 2 H. Baseline hydrochemistry monitoring could provide information on parameters useful for detecting anomalies caused by CO 2 leakage as measures for early warning.

Amplified QCM biosensor for type IV collagenase based on collagenase-cleavage of gold nanoparticles functionalized peptide.

PubMed

Dong, Zong-Mu; Jin, Xin; Zhao, Guang-Chao

2018-05-30

The present study develops a rapid, simple and efficient method for the determination of type IV collagenase by using a specific peptide-modified quartz crystal microbalance (QCM). A small peptide (P1), contains a specific sequence (Pro-Gly) and a terminal cysteine, was synthetized and immobilized to the surface of QCM electrode via the reaction between Au and thiol of the cysteine. The peptide bond between proline and glycine can be specific hydrolyzed cleavage by type IV collagenase, which enabled the modified electrode with a high selectivity toward type IV collagenase. The cleaving process caused a frequency change of QCM to give a signal related to the concentration of type IV collagenase. The morphologies of the modified electrodes were characterized by scanning electron microscope (SEM) and the specific hydrolyzed cleavage process was monitored by QCM. When P1 was modified with gold nanoparticles (P1-Au NPs), the signal could be amplified to further enhance the sensitivity of the designed sensor due to the high-mass of the modified Au NPs. Compared the direct unamplified assay, the values obtained for the limit of detection for type IV collagenase was 0.96 ng mL -1 , yielding about 6.5 times of magnitude improvement in sensitivity. This signal enhanced peptide based QCM biosensor for type IV collagenase also showed good selectivity and sensitivity in complex matrix. Copyright © 2018 Elsevier B.V. All rights reserved.

Relationships between structure, ionization profile and sensitivity of exogenous anabolic steroids under electrospray ionization and analysis in human urine using liquid chromatography-tandem mass spectrometry.

PubMed

Cha, Eunju; Kim, Sohee; Kim, Hee Won; Lee, Kang Mi; Kim, Ho Jun; Kwon, Oh-Seung; Lee, Jaeick

2016-04-01

The relationships between the ionization profile, sensitivity, and structures of 64 exogenous anabolic steroids (groups I-IV) was investigated under electrospray ionization (ESI) conditions. The target analytes were ionized as [M + H](+) or [M + H-nH2 O](+) in the positive mode, and these ions were used as precursor ions for selected reaction monitoring analysis. The collision energy and Q3 ions were optimized based on the sensitivity and selectivity. The limits of detection (LODs) were 0.05-20 ng/mL for the 64 steroids. The LODs for 38 compounds, 14 compounds and 12 compounds were in the range of 0.05-1, 2-5 and 10-20 ng/mL, respectively. Steroids including the conjugated keto-functional group at C3 showed good proton affinity and stability, and generated the [M + H](+) ion as the most abundant precursor ion. In addition, the LODs of steroids using the [M + H](+) ion as the precursor ion were mostly distributed at low concentrations. In contrast, steroids containing conjugated/unconjugated hydroxyl functional groups at C3 generated [M + H - H2 O](+) or [M + H - 2H2 O](+) ions, and these steroids showed relatively high LODs owing to poor stability and multiple ion formation. An LC-MS/MS method based on the present ionization profile was developed and validated for the determination of 78 steroids (groups I-V) in human urine. Copyright © 2015 John Wiley & Sons, Ltd.

Bioanalysis of sulprostone, a prostaglandin E2 analogue and selective EP3 agonist, in monkey plasma by liquid chromatography-tandem mass spectrometry.

PubMed

Shi, Yifan; Rankin, Matthew M; Norquay, Lisa D; Weng, Naidong; Patel, Shefali

2018-05-25

Sulprostone is a potent prostaglandin E 2 (PGE 2 ) analogue and one of the first identified selective G-protein-coupled receptor 3 (EP 3 ) agonists. It has been investigated as a potential antiulcer agent and frequently used in the research of EP 3 antagonist. To assist pharmacokinetic and pharmacodynamic studies, a rapid and sensitive LC-MS/MS method was developed and qualified for the quantitation of sulprostone in monkey plasma. Using electrospray ionization mass spectrometry, an ammonium adduct in positive mode was chosen for analysis which had seven times of the sensitivity of the depronated ion in negative mode. Latanoprost, a prostaglandin F 2α analogue, was used as the internal standard while good sensitivity and chromatography were obtained on a 2.6 μm core-shell column with pentafluorophenyl stationary phase. An assay dynamic range of 2 to 4000 ng/mL was achieved with a sample volume of 25 μL plasma on a Sciex API4000 instrument with simple protein precipitation. Several esterase inhibitors including sodium fluoride (NaF), phenylmethanesulfonyl fluoride (PMSF), diisopropylfluorophosphate (DFP), paraoxon and dichlorvos as well as wet ice conditions were explored for the stabilization of sulprostone in monkey plasma. The developed method was successfully applied for the evaluation of pharmacokinetics of sulprostone after intravenous administration of 0.5 mg/kg to cynomolgus monkey. Copyright © 2018 Elsevier B.V. All rights reserved.

Chemical vapor detection using a capacitive micromachined ultrasonic transducer.

PubMed

Lee, Hyunjoo J; Park, Kwan Kyu; Kupnik, Mario; Oralkan, O; Khuri-Yakub, Butrus T

2011-12-15

Distributed sensing of gas-phase chemicals using highly sensitive and inexpensive sensors is of great interest for many defense and consumer applications. In this paper we present ppb-level detection of dimethyl methylphosphonate (DMMP), a common simulant for sarin gas, with a ppt-level resolution using an improved capacitive micromachined ultrasonic transducer (CMUT) as a resonant chemical sensor. The improved CMUT operates at a higher resonant frequency of 47.7 MHz and offers an improved mass sensitivity of 48.8 zg/Hz/μm(2) by a factor of 2.7 compared to the previous CMUT sensors developed. A low-noise oscillator using the CMUT resonant sensor as the frequency-selective device was developed for real-time sensing, which exhibits an Allan deviation of 1.65 Hz (3σ) in the presence of a gas flow; this translates into a mass resolution of 80.5 zg/μm(2). The CMUT resonant sensor is functionalized with a 50-nm thick DKAP polymer developed at Sandia National Laboratory for dimethyl methylphosphonate (DMMP) detection. To demonstrate ppb-level detection of the improved chemical sensor system, the sensor performance was tested at a certified lab (MIT Lincoln Laboratory), which is equipped with an experimental chemical setup that reliably and accurately delivers a wide range of low concentrations down to 10 ppb. We report a high volume sensitivity of 34.5 ± 0.79 pptv/Hz to DMMP and a good selectivity of the polymer to DMMP with respect to dodecane and 1-octanol.

Molecularly imprinted coated graphene oxide solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of phloxine B in coffee bean.

PubMed

Zhai, Haiyun; Su, Zihao; Chen, Zuanguang; Liu, Zhenping; Yuan, Kaisong; Huang, Lu

2015-03-20

A method was developed to sensitively determine phloxine B in coffee bean by molecularly imprinted polymers (MIPs) coated graphene oxide (GO) solid-phase extraction (GO-MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC-LIF). The GO-MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using GO as supporting material, phloxine B, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade GO-MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions. The GO-MIPs were characterized by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR). The mean recoveries of phloxine B in coffee bean ranged from 89.5% to 91.4% and the intra-day and inter-day relative standard deviation (RSD) values all ranged from 3.6% to 4.7%. Good linearity was obtained over 0.001-2.0 μg mL(-1) (r=0.9995) with the detection limit (S/N=3) of 0.075 ng mL(-1). Under the selected conditions, enrichment factors of over 90-fold were obtained and extraction on the monolithic column effectively cleaned up the coffee bean matrix. The results demonstrated that the proposed GO-MISPE HPLC-LIF method can be applied to sensitively determine phloxine B in coffee bean. Copyright © 2015 Elsevier B.V. All rights reserved.

Poly(1-vinylimidazole) functionalized magnetic ion imprinted polymer for fast and selective extraction of trace gold in geological, environmental and biological samples followed by graphite furnace atomic absorption spectrometry detection

NASA Astrophysics Data System (ADS)

Zhao, Bingshan; He, Man; Chen, Beibei; Xu, Hongrun; Hu, Bin

2018-05-01

In this study, poly(1-vinylimidazole) functionalized gold ion imprinted polymer coated magnetic nanoparticles (MNPs@PVIM-Au-IIP) were prepared and characterized. The adsorption behaviors of the prepared MNPs@PVIM-Au-IIP toward gold ions (Au(III)) were studied, it was found that MNPs@PVIM-Au-IIP has good selectivity, high adsorption capacity (185.4 mg g-1) and fast adsorption kinetic for Au(III). Based on it, a new method of ion imprinted magnetic solid phase extraction (II-MSPE) coupled with graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the analysis of trace Au(III) in real samples with complicated matrix. Factors affecting MSPE including sample pH, desorption reagent, elution concentration and volume, elution time, sample volume and adsorption time were optimized. With high enrichment factor of 100-fold, the detection limit of the proposed method is 7.9 ng L-1 for Au(III) with the relative standard deviation of 7.4% (c = 50 ng L-1, n = 7). In order to validate the accuracy of the proposed method, the Certified Reference Material of GBW07293 geological sample (platinpalladium ore) was analyzed, and the determined value was in good agreement with the certified value. The proposed II-MSPE-GFAAS method is simple, fast, selective, sensitive and has been successfully applied in the determination of trace Au in ore, sediment, environmental water and human urine samples with satisfactory results.

New potentiometric transducer based on a Mn(II) [2-formylquinoline thiosemicarbazone] complex for static and hydrodynamic assessment of azides.

PubMed

Kamel, Ayman H

2015-11-01

A new potentiometric transducer for selective recognition of azide is characterized and developed. The PVC plasticized based sensor incorporates Mn(II) [2-formylquinoline thiosemicarbazone] complex in the presence of tri dodecyl methyl ammonium chloride (TDMAC) as a lipophilic cationic additive. The sensor displayed a near-Nernstian response for azide over 1.0×10(-2)-1.0×10(-5) mol L(-1), with an anionic slope of -55.8±0.6 mV decade(-1) and lower limit of detection 0.34 µg mL(-1). The sensor was pH independent in the range 5.5-9 and presented good selectivity features towards several inorganic anions, and it is easily used in a flow injection system and compared with a tubular detector. The intrinsic characteristics of the detector in a low dispersion manifold were determined and compared with data obtained under a hydrodynamic mode of operation. This simple and inexpensive automation, with a good potentiometric detector, enabled the analysis of ~33 samples h(-1) without requiring pre-treatment procedures. The proposed method is also applied to the analysis of trace levels of azide in primer mixtures. Significantly improved accuracy, precision, response time, stability and selectivity were offered by these simple and cost-effective potentiometric sensor compared with other standard techniques. The method has the requisite accuracy, sensitivity and precision to determine azide ions. Copyright © 2015 Elsevier B.V. All rights reserved.

Breath analysis using external cavity diode lasers: a review

NASA Astrophysics Data System (ADS)

Bayrakli, Ismail

2017-04-01

Most techniques that are used for diagnosis and therapy of diseases are invasive. Reliable noninvasive methods are always needed for the comfort of patients. Owing to its noninvasiveness, ease of use, and easy repeatability, exhaled breath analysis is a very good candidate for this purpose. Breath analysis can be performed using different techniques, such as gas chromatography mass spectrometry (MS), proton transfer reaction-MS, and selected ion flow tube-MS. However, these devices are bulky and require complicated procedures for sample collection and preconcentration. Therefore, these are not practical for routine applications in hospitals. Laser-based techniques with small size, robustness, low cost, low response time, accuracy, precision, high sensitivity, selectivity, low detection limit, real-time, and point-of-care detection have a great potential for routine use in hospitals. In this review paper, the recent advances in the fields of external cavity lasers and breath analysis for detection of diseases are presented.

Fast classification of hazelnut cultivars through portable infrared spectroscopy and chemometrics

NASA Astrophysics Data System (ADS)

Manfredi, Marcello; Robotti, Elisa; Quasso, Fabio; Mazzucco, Eleonora; Calabrese, Giorgio; Marengo, Emilio

2018-01-01

The authentication and traceability of hazelnuts is very important for both the consumer and the food industry, to safeguard the protected varieties and the food quality. This study investigates the use of a portable FTIR spectrometer coupled to multivariate statistical analysis for the classification of raw hazelnuts. The method discriminates hazelnuts from different origins/cultivars based on differences of the signal intensities of their IR spectra. The multivariate classification methods, namely principal component analysis (PCA) followed by linear discriminant analysis (LDA) and partial least square discriminant analysis (PLS-DA), with or without variable selection, allowed a very good discrimination among the groups, with PLS-DA coupled to variable selection providing the best results. Due to the fast analysis, high sensitivity, simplicity and no sample preparation, the proposed analytical methodology could be successfully used to verify the cultivar of hazelnuts, and the analysis can be performed quickly and directly on site.

Design of a Selective and Sensitive PVC-Membrane Potentiometric Sensor for Strontium Ion Based on 1,10-Diaza-5,6-benzo-4,7-dioxacyclohexadecane-2,9-dione as a Neutral Ionophore

PubMed Central

Shamsipur, Mojtaba; Kazemi, Sayed Yahya; Sharghi, Hashem

2007-01-01

A novel PVC membrane sensor for the Sr2+ ion based on 1,10-diaza-5,6-benzo-4,7-dioxacyclohexadecane-2,9-dione has been prepared. The sensor possesses a Nernstian slope of 30.0 ± 0.6 mV decade-1 over a wide linear concentration range of 1.6 × 10-6-3.0 ×10-3 M with a detection limit of 6.3 ×10-7 M. It has a fast response time of <15 s and can be used for at least two months without any considerable divergence in potential. The potentiometric response is independent of the pH of test solution in the pH range 4.3-9.4. The proposed electrode shows good selectivities over a variety of alkali, alkaline earth, and transition metal ions.

Synthesis of isocryptolepine analogues and their structure-activity relationship studies as antiplasmodial and antiproliferative agents.

PubMed

Aroonkit, Pasuk; Thongsornkleeb, Charnsak; Tummatorn, Jumreang; Krajangsri, Suppachai; Mungthin, Mathirut; Ruchirawat, Somsak

2015-04-13

Novel isocryptolepine analogues have been conveniently synthesized and evaluated for antimalarial and antiproliferative activities. We have found 3-fluoro-8-bromo-isocryptolepine (1n) to have the highest activities against chloroquine-resistant K1, chloroquine-sensitive 3D7, and chloroquine- and mefloquine-resistant SKF58 and SRIV35 strains. Several fluorine-substituted analogues (1b, 1n, and 1q) also showed excellent selectivities while maintaining good to excellent activities against all four Plasmodium falciparum strains. Additionally, antiproliferative properties of isocryptolepine derivatives against HepG2, HuCCA-1, MOLT-3 and A549 cancer cell lines are reported for the first time in this study. 2-Chloroisocryptolepine (1c) and benzo-fused-2-chloroisocryptolepine (1i) showed significant bioactivities whereas several novel fluorinated compounds and 2-chloro-8-bromoisocryptolepine (1f) displayed excellent selectivities. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Graphene-multiwall carbon nanotube-gold nanocluster composites modified electrode for the simultaneous determination of ascorbic acid, dopamine, and uric acid.

PubMed

Liu, Xiaofang; Wei, Shaping; Chen, Shihong; Yuan, Dehua; Zhang, Wen

2014-08-01

In this paper, graphene-multiwall carbon nanotube-gold nanocluster (GP-MWCNT-AuNC) composites were synthesized and used as modifier to fabricate a sensor for simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The electrochemical behavior of the sensor was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The combination of GP, MWCNTs, and AuNCs endowed the electrode with a large surface area, good catalytic activity, and high selectivity and sensitivity. The linear response range for simultaneous detection of AA, DA, and UA at the sensor were 120-1,701, 2-213, and 0.7-88.3 μM, correspondingly, and the detection limits were 40, 0.67, and 0.23 μM (S/N=3), respectively. The proposed method offers a promise for simple, rapid, selective, and cost-effective analysis of small biomolecules.

A thiourea derivative as potential ionophore for copper sensing

NASA Astrophysics Data System (ADS)

Ying, Kook Shih; Heng, Lee Yook; Hassan, Nurul Izzaty; Hasbullah, Siti Aishah

2018-04-01

A new thiourea derivative, N1,N3-bis[[3,5-bis(trifluoromethyl)phenyl]carbamothioyl]isophthalamide (TPC), as a potential copper ionophore was investigated. TPC was immobilized via drop casting method into poly(n-butyl acrylate) pBA membrane and the sensor was characterized by potentiometric method. The sensor fabricated based on TPC showed a Nernstian response towards copper ion with the slope of 27.07±2.84 mV/decade in the range of 1.0×10-6 - 1.0-10-4 M and limit of detection of 6.24 × 10-7 M. In addition, based on the separate solution method (SSM), the logarithm selectivity coefficients were less than -3.00 for monovalent, divalent and trivalent cations that are present in the environmental water samples such as K+, Ca2+, Mg2+ and Fe3+. This confirmed that the sensor fabricated with TPC exhibited good sensitivity and selectivity towards copper ion.

A Series of Fluorescent and Colorimetric Chemodosimeters for Selective Recognition of Cyanide Based on the FRET Mechanism.

PubMed

Hua, Ying-Xi; Shao, Yongliang; Wang, Ya-Wen; Peng, Yu

2017-06-16

A series of fluorescence "turn-on" probes (PY, AN, NA, B1, and B2) have been developed and successfully applied to detect cyanide anions based on the Michael addition reaction and FRET mechanism. These probes demonstrated good selectivity, high sensitivity, and very fast recognition for CN - . In particular, the fluorescence response of probe NA finished within 3 s. Low limits of detection (down to 63 nM) are also obtained in these probes with remarkable fluorescence enhancement factors. In addition, fluorescence colors of these probes turned to blue, yellow, or orange upon sensing CN - . In UV-vis mode, all of them showed ratiometric response for CN - . 1 H NMR titration experiments and TDDFT calculations were taken to verify the mechanism of the specific reaction and fluorescence properties of the corresponding compounds. Moreover, silica gel plates with these probes were also fabricated and utilized to detect cyanide.

Sensitivity assessment of freshwater macroinvertebrates to pesticides using biological traits.

PubMed

Ippolito, A; Todeschini, R; Vighi, M

2012-03-01

Assessing the sensitivity of different species to chemicals is one of the key points in predicting the effects of toxic compounds in the environment. Trait-based predicting methods have proved to be extremely efficient for assessing the sensitivity of macroinvertebrates toward compounds with non specific toxicity (narcotics). Nevertheless, predicting the sensitivity of organisms toward compounds with specific toxicity is much more complex, since it depends on the mode of action of the chemical. The aim of this work was to predict the sensitivity of several freshwater macroinvertebrates toward three classes of plant protection products: organophosphates, carbamates and pyrethroids. Two databases were built: one with sensitivity data (retrieved, evaluated and selected from the U.S. Environmental Protection Agency ECOTOX database) and the other with biological traits. Aside from the "traditional" traits usually considered in ecological analysis (i.e. body size, respiration technique, feeding habits, etc.), multivariate analysis was used to relate the sensitivity of organisms to some other characteristics which may be involved in the process of intoxication. Results confirmed that, besides traditional biological traits, related to uptake capability (e.g. body size and body shape) some traits more related to particular metabolic characteristics or patterns have a good predictive capacity on the sensitivity to these kinds of toxic substances. For example, behavioral complexity, assumed as an indicator of nervous system complexity, proved to be an important predictor of sensitivity towards these compounds. These results confirm the need for more complex traits to predict effects of highly specific substances. One key point for achieving a complete mechanistic understanding of the process is the choice of traits, whose role in the discrimination of sensitivity should be clearly interpretable, and not only statistically significant.

Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature.

PubMed

Villa, E; Aja, B; de la Fuente, L; Artal, E

2016-01-01

This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.

A label free aptasensor for Ochratoxin A detection in cocoa beans: An application to chocolate industries.

PubMed

Mishra, Rupesh K; Hayat, Akhtar; Catanante, Gaëlle; Ocaña, Cristina; Marty, Jean-Louis

2015-08-19

Contamination of food by mycotoxin occurs in minute/trace quantities. Nearly 92.5% of the cocoa samples present Ochratoxin A (OTA) levels at trace quantity. Hence, there is a necessity for a highly sensitive and selective device that can detect and quantify these organic toxins in various matrices such as cocoa beans. This work reports for the first time, a facile and label-free electrochemical impedimetric aptasensor for rapid detection and quantitation of OTA in cocoa beans. The developed aptasensor was constructed based on the diazonium-coupling reaction mechanism for the immobilization of anti-OTA-aptamer on screen printed carbon electrodes (SPCEs). The aptasensor exhibited a very good limit of detection (LOD) as low as 0.15 ng/mL, with added advantages of good selectivity and reproducibility. The increase in electron transfer resistance was linearly proportional to the OTA concentration in the range 0.15-2.5 ng/mL, with an acceptable recovery percentage (91-95%, RSD = 4.8%) obtained in cocoa samples. This work can facilitate a general model for the detection of OTA in cocoa beans based on the impedimetric aptasensor. The analysis can be performed onsite with pre-constructed and aptamer modified electrodes employing a portable EIS set up. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel EIS field effect structures coated with TESUD-PPy-PVC-dibromoaza[7]helicene matrix for potassium ions detection.

PubMed

Tounsi, Moncef; Ben Braiek, Mourad; Barhoumi, Houcine; Baraket, Abdoullatif; Lee, Michael; Zine, Nadia; Maaref, Abderrazak; Errachid, Abdelhamid

2016-04-01

In this work, we describe the development of new Aza[7]helicene-containing PVC-based membranes for the K(+) ions quantification. Here, silicon nitride-based structures (Si-p/SiO2/Si3N4) were developed and the surface was activated, functionalized with an aldehyde-silane (11-(Triethoxysilyl)undecanal (TESUD)), functionalized with polypyrrole (PPy), and coated with the polyvinylchloride (PVC)-membrane containing the Aza[7]helicene as ionophore. All stages of functionalization process have been thoroughly studied by contact angle measurements (CAMs) and atomic force microscopy (AFM). The developed ion-selective electrode (ISE) was then applied using electrochemical impedance spectroscopy (EIS) for the detection of potassium ions. A linear range was observed between 1.0 × 10(-8) M to 1.0 × 10(-3) M and a detection limit of 1.0 × 10(-8) M was observed. The EIS results have showed a good sensitivity to potassium ion using this novel technique. The target helicene exhibited good solubility and excellent thermal stability with a high decomposition temperature (Td > 300 °C) and it indicates that helicene may be a promising material as ionophore for ion-selective electrodes (ISEs) elaboration. Copyright © 2016 Elsevier B.V. All rights reserved.

Considerations in high resolution skeletal muscle DTI using single-shot EPI with stimulated echo preparation and SENSE

PubMed Central

Karampinos, Dimitrios C.; Banerjee, Suchandrima; King, Kevin F.; Link, Thomas M.; Majumdar, Sharmila

2011-01-01

Previous studies have shown that skeletal muscle diffusion tensor imaging (DTI) can non-invasively probe changes in the muscle fiber architecture and microstructure in diseased and damaged muscles. However, DTI fiber reconstruction in small muscles and in muscle regions close to aponeuroses and tendons remains challenging because of partial volume effects. Increasing the spatial resolution of skeletal muscle single-shot diffusion weighted (DW)-EPI can be hindered by the inherently low SNR of muscle DW-EPI due to the short muscle T2 and the high sensitivity of single-shot EPI to off-resonance effects and T2* blurring. In the present work, eddy-current compensated diffusion-weighted stimulated echo preparation is combined with sensitivity encoding (SENSE) to maintain good SNR properties and reduce the sensitivity to distortions and T2* blurring in high resolution skeletal muscle single-shot DW-EPI. An analytical framework is developed for optimizing the reduction factor and diffusion weighting time to achieve maximum SNR. Arguments for the selection of the experimental parameters are then presented considering the compromise between SNR, B0-induced distortions, T2* blurring effects and tissue incoherent motion effects. Based on the selected parameters in a high resolution skeletal muscle single-shot DW-EPI protocol, imaging protocols at lower acquisition matrix sizes are defined with matched bandwidth in the phase-encoding direction and SNR. In vivo results show that high resolution skeletal muscle DTI with minimized sensitivity to geometric distortions and T2* blurring is feasible using the proposed methodology. In particular, a significant benefit is demonstrated from reducing partial volume effects on resolving multi-pennate muscles and muscles with small cross sections in calf muscle DTI. PMID:22081519

Xanthine oxidase functionalized Ta2O5 nanostructures as a novel scaffold for highly sensitive SPR based fiber optic xanthine sensor.

PubMed

Kant, Ravi; Tabassum, Rana; Gupta, Banshi D

2018-01-15

Fabrication and characterization of a surface plasmon resonance based fiber optic xanthine sensor using entrapment of xanthine oxidase (XO) enzyme in several nanostructures of tantalum (v) oxide (Ta 2 O 5 ) have been reported. Chemical route was adopted for synthesizing Ta 2 O 5 nanoparticles, nanorods, nanotubes and nanowires while Ta 2 O 5 nanofibers were prepared by electrospinning technique. The synthesized Ta 2 O 5 nanostructures were characterized by photoluminescence, scanning electron microscopy, UV-Visible spectra and X-ray diffraction pattern. The probes were fabricated by coating an unclad core of the fiber with silver layer followed by the deposition of XO entrapped Ta 2 O 5 nanostructures. The crux of sensing mechanism relies on the modification of dielectric function of sensing layer upon exposure to xanthine solution of diverse concentrations, reflected in terms of shift in resonance wavelength. The sensing probe coated with XO entrapped Ta 2 O 5 nanofibers has been turned out to possess maximum sensitivity amongst the synthesized nanostructures. The probe was optimized in terms of pH of the sample and the concentration of XO entrapped in Ta 2 O 5 nanofibers. The optimized sensing probe possesses a remarkably good sensitivity of 26.2nm/µM in addition to linear range from 0 to 3µM with an invincible LOD value of 0.0127µM together with a response time of 1min. Furthermore, probe selectivity with real sample analysis ensure the usage of the sensor for practical scenario. The results reported open a novel perspective towards a sensitive, rapid, reliable and selective detection of xanthine. Copyright © 2017 Elsevier B.V. All rights reserved.

[Non-invasive fibrosis indexes in predicting acute liver function deterioration after transcatheter arterial chemoembolization].

PubMed

Song, Y P; Zhao, Q Y; Li, S; Wang, H; Wu, P H

2016-03-08

To investigate the ability of two non-invasive fibrosis indexes-APRI, i. e. aspartate transaminase (AST) to platelet (PLT) ratio index, and fibrosis index based on the 4 factors (FIB-4)score in predicting ALFD in patients with unresectable primary HCC and underwent TACE. Clinical data of those patients treated with TACE in Department of Interventional Radiology of the Center from Jan 2010 to Aug 2014 were investigated retrospectively. A total of 366 cases were enrolled after randomized selection, 62 (18.5%) of which developed ALFD after TACE. Child-Pugh score, APRI and FIB-4 score in every case were calculated, receiver operating characteristic (ROC) curve of each model were performed and the predictive abilities of them were assessed by area under the curve (AUC), positive predictive value (PPV), negative predictive value (NPV), sensitivity and specificity. The AUC of Child-Pugh score, APRI and FIB-4 score were 0.783, 0.752 and 0.758 respectively, while the difference had no significance in statistics, indicating that predictive accuracies of them were similar. APRI≤1.15 and FIB-4≤3.08 had better NPV (90.6% and 93.6%) and sensitivity (65.6% and 80.0%) than Child-Pugh score>6 (NPV=85.8%, sensitivity=27.4%), PPV and specificity of them are 35.7%, 32.9%, 89.5% and 73.7%, 64.2%, 99.3% respectively. Comparing to Child-Pugh score, APRI and FIB-4 score have similar accuracy but better NPV and sensitivity in predicting post-TACE ALFD. Thereafter they are good for selection of low-risk patients for TACE treatment. Candidates with an APRI≤1.15 or a FIB-4≤3.08 or in Child-Pugh a stage are unlikely to develop ALFD thus could receive TACE safely.

Rough sets and Laplacian score based cost-sensitive feature selection

PubMed Central

Yu, Shenglong

2018-01-01

Cost-sensitive feature selection learning is an important preprocessing step in machine learning and data mining. Recently, most existing cost-sensitive feature selection algorithms are heuristic algorithms, which evaluate the importance of each feature individually and select features one by one. Obviously, these algorithms do not consider the relationship among features. In this paper, we propose a new algorithm for minimal cost feature selection called the rough sets and Laplacian score based cost-sensitive feature selection. The importance of each feature is evaluated by both rough sets and Laplacian score. Compared with heuristic algorithms, the proposed algorithm takes into consideration the relationship among features with locality preservation of Laplacian score. We select a feature subset with maximal feature importance and minimal cost when cost is undertaken in parallel, where the cost is given by three different distributions to simulate different applications. Different from existing cost-sensitive feature selection algorithms, our algorithm simultaneously selects out a predetermined number of “good” features. Extensive experimental results show that the approach is efficient and able to effectively obtain the minimum cost subset. In addition, the results of our method are more promising than the results of other cost-sensitive feature selection algorithms. PMID:29912884

Culture, Personality, Health, and Family Dynamics: Cultural Competence in the Selection of Culturally Sensitive Treatments

ERIC Educational Resources Information Center

Sperry, Len

2010-01-01

Cultural sensitivity and cultural competence in the selection of culturally sensitive treatments is a requisite for effective counseling practice in working with diverse clients and their families, particularly when clients present with health issues or medical problems. Described here is a strategy for selecting culturally sensitive treatments…

Quality theory paper writing for medical examinations.

PubMed

Shukla, Samarth; Acharya, Sourya; Acharya, Neema; Shrivastava, Tripti; Kale, Anita

2014-04-01

Aim & Objectives: Developing a tactful paper writing skill, through delivery and depiction of the necessary expressions required for in standard or superior essay writing. Understanding relevance and tact of theoretical expression in exam paper writing Learning Indices of standard or quality theory/essay answer (SAQ/LAQ). Applying knowledge and skill gained through these theory writing exercises and assignments to achieve high or better scores in examinations. The study subjects were divided into two groups- Group A (17 students) and Group B students (10students). The students were selected from II M.B.B.S 4(th) term. Students of Group A were sensitized on how to write a theory paper and went through 4 phases namely pre-sensitization test, sensitization (imparting them with skills of good theory paper writing through home assignments and deliberations/ guidance), post-sensitization test and Evaluation. Students of Group A (17 students) undertook theory tests (twice, i.e. before and after sensitization) and Students of Group B (10 students) who were not sensitized and took the theory test with post sensitized Group A students (random 10 students). Both groups were given general pathology as the test syllabus, taught to both groups in didactic lectures during the last 6 months. The results of pre and Post-sensitization tests from both groups were analyzed. Intra group comparisons (pre sensitized Group A with Post sensitized Group A) and inter group comparisons (Non-sensitized group B with Sensitized Group A) were made. Significant results were found between results of pre and Post-sensitization tests in Group A (intra group analysis) and inter group (Group A and B) Post-sensitization tests, as there was remarkable improvement in student theory paper writing skills post sensitizing the students of Group A. Medical students should be mandatorily guided and exposed to the nuances and tact of writing the theory paper for their examinations, as it definitely gives them better understanding of presentations ultimately improving their score in the theory exams.

Minimal spanning tree algorithm for γ-ray source detection in sparse photon images: cluster parameters and selection strategies

DOE PAGES

Campana, R.; Bernieri, E.; Massaro, E.; ...

2013-05-22

We present that the minimal spanning tree (MST) algorithm is a graph-theoretical cluster-finding method. We previously applied it to γ-ray bidimensional images, showing that it is quite sensitive in finding faint sources. Possible sources are associated with the regions where the photon arrival directions clusterize. MST selects clusters starting from a particular “tree” connecting all the point of the image and performing a cut based on the angular distance between photons, with a number of events higher than a given threshold. In this paper, we show how a further filtering, based on some parameters linked to the cluster properties, canmore » be applied to reduce spurious detections. We find that the most efficient parameter for this secondary selection is the magnitudeM of a cluster, defined as the product of its number of events by its clustering degree. We test the sensitivity of the method by means of simulated and real Fermi-Large Area Telescope (LAT) fields. Our results show that √M is strongly correlated with other statistical significance parameters, derived from a wavelet based algorithm and maximum likelihood (ML) analysis, and that it can be used as a good estimator of statistical significance of MST detections. Finally, we apply the method to a 2-year LAT image at energies higher than 3 GeV, and we show the presence of new clusters, likely associated with BL Lac objects.« less

Poly(3,6-diamino-9-ethylcarbazole) based molecularly imprinted polymer sensor for ultra-sensitive and selective detection of 17-β-estradiol in biological fluids.

PubMed

Liu, Weilu; Li, Haifeng; Yu, Shangmin; Zhang, Jiaxing; Zheng, Weihua; Niu, Liting; Li, Gengen

2018-05-01

In this work, we reported the synthesis of 3, 6-diamino-9-ethylcarbazole and its application as a new monomer for preparation of molecularly imprinted polymer (MIP) electrochemical sensor. The as prepared MIP sensor exhibited ultrahigh sensitivity and selectivity for the detection of 17-β-estradiol in attomolar levels (1 × 10 -18 molL -1 ). The sensor works by detecting the change of the interfacial impedance that is derived from recognition of 17-β-estradiol on the MIP layer. The MIP sensor based on 3, 6-diamino-9-ethylcarbazole monomer revealed better performance than that of unmodified carbazole monomer. The monomer/template ratio, electropolymerization scanning cycles, and the incubation pH values were optimised in order to obtain the best detection efficiency. Under the optimised condition, the MIP sensor exhibits a wide linear range from 1aM to 10μM (1 × 10 -18 ̶ 1 × 10 -5 molL -1 ). A low detection limit of 0.36aM (3.6 × 10 -19 molL -1 ) and a good selectivity towards structurally similar compounds were obtained. The proposed MIP sensor also exhibits long-term stability and applicability in human serum samples. These advantages enabled this MIP sensor to be a promising alternative of electrochemical sensor and may be extended to detection of other endogenous compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

Anticancer drug sensitivity prediction in cell lines from baseline gene expression through recursive feature selection.

PubMed

Dong, Zuoli; Zhang, Naiqian; Li, Chun; Wang, Haiyun; Fang, Yun; Wang, Jun; Zheng, Xiaoqi

2015-06-30

An enduring challenge in personalized medicine is to select right drug for individual patients. Testing drugs on patients in large clinical trials is one way to assess their efficacy and toxicity, but it is impractical to test hundreds of drugs currently under development. Therefore the preclinical prediction model is highly expected as it enables prediction of drug response to hundreds of cell lines in parallel. Recently, two large-scale pharmacogenomic studies screened multiple anticancer drugs on over 1000 cell lines in an effort to elucidate the response mechanism of anticancer drugs. To this aim, we here used gene expression features and drug sensitivity data in Cancer Cell Line Encyclopedia (CCLE) to build a predictor based on Support Vector Machine (SVM) and a recursive feature selection tool. Robustness of our model was validated by cross-validation and an independent dataset, the Cancer Genome Project (CGP). Our model achieved good cross validation performance for most drugs in the Cancer Cell Line Encyclopedia (≥80% accuracy for 10 drugs, ≥75% accuracy for 19 drugs). Independent tests on eleven common drugs between CCLE and CGP achieved satisfactory performance for three of them, i.e., AZD6244, Erlotinib and PD-0325901, using expression levels of only twelve, six and seven genes, respectively. These results suggest that drug response could be effectively predicted from genomic features. Our model could be applied to predict drug response for some certain drugs and potentially play a complementary role in personalized medicine.

a Band Selection Method for High Precision Registration of Hyperspectral Image

NASA Astrophysics Data System (ADS)

Yang, H.; Li, X.

2018-04-01

During the registration of hyperspectral images and high spatial resolution images, too much bands in a hyperspectral image make it difficult to select bands with good registration performance. Terrible bands are possible to reduce matching speed and accuracy. To solve this problem, an algorithm based on Cram'er-Rao lower bound theory is proposed to select good matching bands in this paper. The algorithm applies the Cram'er-Rao lower bound theory to the study of registration accuracy, and selects good matching bands by CRLB parameters. Experiments show that the algorithm in this paper can choose good matching bands and provide better data for the registration of hyperspectral image and high spatial resolution image.

A high performance nonenzymatic electrochemical glucose sensor based on polyvinylpyrrolidone-graphene nanosheets-nickel nanoparticles-chitosan nanocomposite.

PubMed

Liu, Zhiguang; Guo, Yujing; Dong, Chuan

2015-05-01

In this report, a new nanocomposite was successfully synthesized by chemical deposition of nickel nanoparticles (NiNPs) on polyvinylpyrrolidone (PVP) stabilized graphene nanosheets (GNs) with chitosan (CS) as the protective coating. The as obtained nanocomposite (PVP-GNs-NiNPs-CS) was characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Benefiting from the synergistic effect of GNs (large surface area and high conductivity), NiNPs (high electrocatalytic activity towards the glucose oxidation) and CS (good film-forming and antifouling ability), a nonenzymatic electrochemical glucose sensor was established. The nanocomposite displays greatly enhanced electrocatalytic activity towards the glucose oxidation in NaOH solution. The PVP-GNs-NiNPs-CS based electrochemical glucose sensor demonstrates good sensitivity, wide linear range (0.1 μM-0.5 mM), outstanding detection limit (30 nM), attractive selectivity, good reproducibility, high stability as well as prominent feasibility for the real sample analysis. The proposed experiment might open up a new possibility for widespread use of non-enzymatic sensors for monitoring blood glucose owing to its advantages of low cost, simple preparation and excellent properties for glucose detection. Copyright © 2015 Elsevier B.V. All rights reserved.

Nanowire-Assembled Hierarchical ZnCo2O4 Microstructure Integrated with a Low-Power Microheater for Highly Sensitive Formaldehyde Detection.

PubMed

Long, Hu; Harley-Trochimczyk, Anna; Cheng, Siyi; Hu, Hao; Chi, Won Seok; Rao, Ameya; Carraro, Carlo; Shi, Tielin; Tang, Zirong; Maboudian, Roya

2016-11-23

Nanowire-assembled 3D hierarchical ZnCo 2 O 4 microstructure is synthesized by a facile hydrothermal route and a subsequent annealing process. In comparison to simple nanowires, the resulting dandelion-like structure yields more open spaces between nanowires, which allow for better gas diffusion and provide more active sites for gas adsorption while maintaining good electrical conductivity. The hierarchical ZnCo 2 O 4 microstructure is integrated on a low-power microheater platform without using binders or conductive additives. The hierarchical structure of the ZnCo 2 O 4 sensing material provides reliable electrical connection across the sensing electrodes. The resulting sensor exhibits an ultralow detection limit of 3 ppb toward formaldehyde with fast response and recovery as well as good selectivity to CO, H 2 , and hydrocarbons such as n-pentane, propane, and CH 4 . The sensor only consumes ∼5.7 mW for continuous operation at 300 °C with good long-term stability. The excellent sensing performance of this hierarchical structure based sensor suggests the advantages of combining such structures with microfabricated heaters for practical low-power sensing applications.

Monitoring the contents of six steroidal and phenolic endocrine disrupting chemicals in chicken, fish and aquaculture pond water samples using pre-column derivatization and dispersive liquid-liquid microextraction with the aid of experimental design methodology.

PubMed

Wu, Hongliang; Li, Guoliang; Liu, Shucheng; Hu, Na; Geng, Dandan; Chen, Guang; Sun, Zhiwei; Zhao, Xianen; Xia, Lian; You, Jinmao

2016-02-01

This research established a sensitive and efficient pre-column derivatization HPLC method based on dispersive liquid-liquid microextraction (DLLME) for the simultaneous determination of six steroidal and phenolic endocrine disrupting chemicals (EDCs). In this study, EDCs were firstly labeled by the derivatization reagent 2-(11H-benzo[a]carbazol-11-yl) ethyl carbonochloridate (BCEC-Cl) and then extracted by DLLME. The response surface methodology was employed to investigate the key parameters of pre-column derivatization and DLLME. Under the optimal conditions, a good linear relationship between the peak area and the concentration of analytes was observed with correlation coefficients of >0.9991. Limits of detection for all EDCs derivatives were achieved within the range of 0.02-0.07 μg L(-1). The proposed method has the advantages of simple operation, low consumption of organic solvent, saving time, low output limit and good selectivity. When applied to several food and water samples analysis, it demonstrated good applicability for the determination of EDCs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Molecularly imprinted polymer microspheres prepared by Pickering emulsion polymerization for selective solid-phase extraction of eight bisphenols from human urine samples.

PubMed

Yang, Jiajia; Li, Yun; Wang, Jincheng; Sun, Xiaoli; Cao, Rong; Sun, Hao; Huang, Chaonan; Chen, Jiping

2015-05-04

The bisphenol A (BPA) imprinted polymer microspheres were prepared by simple Pickering emulsion polymerization. Compared to traditional bulk polymerization, both high yields of polymer and good control of particle sizes were achieved. The characterization results of scanning electron microscopy and nitrogen adsorption-desorption measurements showed that the obtained molecularly imprinted polymer microsphere (MIPMS) particles possessed regular spherical shape, narrow diameter distribution (30-60 μm), a specific surface area (S(BET)) of 281.26 m(2) g(-1) and a total pore volume (V(t)) of 0.459 cm(3) g(-1). Good specific adsorption capacity for BPA was obtained in the sorption experiment and good class selectivity for BPA and its seven structural analogs (bisphenol F, bisphenol B, bisphenol E, bisphenol AF, bisphenol S, bisphenol AP and bisphenol Z) was demonstrated by the chromatographic evaluation experiment. The MIPMS as solid-phase extraction (SPE) packing material was then evaluated for extraction and clean-up of these bisphenols (BPs) from human urine samples. An accurate and sensitive analytical method based on the MIPMS-SPE coupled with HPLC-DAD has been successfully established for simultaneous determination of eight BPs from human urine samples with detection limits of 1.2-2.2 ng mL(-1). The recoveries of BPs for urine samples at two spiking levels (100 and 500 ng mL(-1) for each BP) were in the range of 81.3-106.7% with RSD values below 8.3%. Copyright © 2015 Elsevier B.V. All rights reserved.

A Meta-analysis for the Diagnostic Performance of Transient Elastography for Clinically Significant Portal Hypertension.

PubMed

You, Myung-Won; Kim, Kyung Won; Pyo, Junhee; Huh, Jimi; Kim, Hyoung Jung; Lee, So Jung; Park, Seong Ho

2017-01-01

We aimed to evaluate the correlation between liver stiffness measurement using transient elastography (TE-LSM) and hepatic venous pressure gradient and the diagnostic performance of TE-LSM in assessing clinically significant portal hypertension through meta-analysis. Eleven studies were included from thorough literature research and selection processes. The summary correlation coefficient was 0.783 (95% confidence interval [CI], 0.737-0.823). Summary sensitivity, specificity and area under the hierarchical summary receiver operating characteristic curve (AUC) were 87.5% (95% CI, 75.8-93.9%), 85.3 % (95% CI, 76.9-90.9%) and 0.9, respectively. The subgroup with low cut-off values of 13.6-18 kPa had better summary estimates (sensitivity 91.2%, specificity 81.3% and partial AUC 0.921) than the subgroup with high cut-off values of 21-25 kPa (sensitivity 71.2%, specificity 90.9% and partial AUC 0.769). In summary, TE-LSM correlated well with hepatic venous pressure gradient and represented good diagnostic performance in diagnosing clinically significant portal hypertension. For use as a sensitive screening tool, we propose using low cut-off values of 13.6-18 kPa in TE-LSM. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

A new electrochemical sensor for highly sensitive and selective detection of nitrite in food samples based on sonochemical synthesized Calcium Ferrite (CaFe2O4) clusters modified screen printed carbon electrode.

PubMed

Balasubramanian, Paramasivam; Settu, Ramki; Chen, Shen-Ming; Chen, Tse-Wei; Sharmila, Ganapathi

2018-08-15

Herein, we report a novel, disposable electrochemical sensor for the detection of nitrite ions in food samples based on the sonochemical synthesized orthorhombic CaFe 2 O 4 (CFO) clusters modified screen printed electrode. As synthesized CFO clusters were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and amperometry (i-t). Under optimal condition, the CFO modified electrode displayed a rapid current response to nitrite, a linear response range from 0.016 to 1921 µM associated with a low detection limit 6.6 nM. The suggested sensor also showed the excellent sensitivity of 3.712 μA μM -1  cm -2 . Furthermore, a good reproducibility, long-term stability and excellent selectivity were also attained on the proposed sensor. In addition, the practical applicability of the sensor was investigated via meat samples, tap water and drinking water, and showed desirable recovery rate, representing its possibilities for practical application. Copyright © 2018 Elsevier Inc. All rights reserved.

Polydopamine Nanotubes as an Effective Fluorescent Quencher for Highly Sensitive and Selective Detection of Biomolecules Assisted with Exonuclease III Amplification.

PubMed

Fan, Daoqing; Zhu, Xiaoqing; Zhai, Qingfeng; Wang, Erkang; Dong, Shaojun

2016-09-20

In this work, the effective fluorescence quenching ability of polydopamine nanotubes (PDANTs) toward various fluorescent dyes was studied and further applied to fluorescent biosensing for the first time. The PDANTs could quench the fluorophores with different emission frequencies, aminomethylcoumarin acetate (AMCA), 6-carboxyfluorescein (FAM), 6-carboxytetramethylrhodamine (TAMRA), and Cy5. All the quenching efficiencies reached to more than 97%. Taking advantage of PDANTs' different affinities toward ssDNA and dsDNA and utilizing the complex of FAM-labeled ssDNA and PDANTs as a sensing platform, we achieved highly sensitive and selective detection of human immunodeficiency virus (HIV) DNA and adenosine triphosphate (ATP) assisted with Exonuclease III amplification. The limits of detection (LODs) of HIV DNA and ATP reached to 3.5 pM and 150 nM, respectively, which were all lower than that of previous nanoquenchers with Exo III amplification, and the platform also presented good applicability in biological samples. Fluorescent sensing applications of this nanotube enlightened other targets detection based upon it and enriched the building blocks of fluorescent sensing platforms. This polydopamine nanotube also possesses excellent biocompatibility and biodegradability, which is suitable for future drug delivery, cell imaging, and other biological applications.

An excited-state intramolecular photon transfer fluorescence probe for localizable live cell imaging of cysteine

NASA Astrophysics Data System (ADS)

Liu, Wei; Chen, Wen; Liu, Si-Jia; Jiang, Jian-Hui

2017-03-01

Small molecule probes suitable for selective and specific fluorescence imaging of some important but low-concentration intracellular reactive sulfur species such as cysteine (Cys) pose a challenge in chemical biology. We present a readily available, fast-response fluorescence probe CHCQ-Ac, with 2-(5‧-chloro-2-hydroxyl-phenyl)-6-chloro-4(3 H)-quinazolinone (CHCQ) as the fluorophore and acrylate group as the functional moiety, that enables high-selectivity and high-sensitivity for detecting Cys in both solution and biological system. After specifically reacted with Cys, the probe undergoes a seven-membered intramolecular cyclization and released the fluorophore CHCQ with excited-state intramolecular photon transfer effect. A highly fluorescent, insoluble aggregate was then formed to facilitate high-sensitivity and high-resolution imaging. The results showed that probe CHCQ-Ac affords a remarkably large Stokes shift and can detect Cys under physiological pH condition with no interference from other analytes. Moreover, this probe was proved to have excellent chemical stability, low cytotoxicity and good cell permeability. Our design of this probe provides a novel potential tool to visualize and localize cysteine in bioimaging of live cells that would greatly help to explore various Cys-related physiological and pathological cellular processes in cell biology and diagnostics.

A sensitive electrochemical immunosensor based on poly(2-aminobenzylamine) film modified screen-printed carbon electrode for label-free detection of human immunoglobulin G.

PubMed

Putnin, Thitirat; Jumpathong, Watthanachai; Laocharoensuk, Rawiwan; Jakmunee, Jaroon; Ounnunkad, Kontad

2018-08-01

This work focuses on fabricating poly(2-aminobenzylamine)-modified screen-printed carbon electrode as an electrochemical immunosensor for the label-free detection of human immunoglobulin G. To selectively detect immunoglobulin G, the anti-immunoglobulin G antibody with high affinity to immunoglobulin G was covalently linked with the amine group of poly(2-aminobenzylamine) film-deposited screen-printed carbon electrode. The selectivity for immunoglobulin G was subsequently assured by being challenged with redox-active interferences and adventitious adsorption did not significantly interfere the analyte signal. To obviate the use of costly secondary antibody, the [Fe(CN) 6 ] 4-/3- redox probe was instead applied to measure the number of human immunoglobulin G through the immunocomplex formation that is quantitatively related to the level of the differential pulse voltammetric current. The resulting immunosensor exhibited good sensitivity with the detection limit of 0.15 ng mL -1 , limit of quantitation of 0.50 ng mL -1 and the linear range from 1.0 to 50 ng mL -1 . Given those striking analytical performances and the affordability arising from using cheap screen-printed carbon electrode with label-free detection, the immunosensor serves as a promising model for the next-step development of a diagnostic tool.

Simple and suitable immunosensor for β-lactam antibiotics analysis in real matrixes: milk, serum, urine.

PubMed

Merola, Giovanni; Martini, Elisabetta; Tomassetti, Mauro; Campanella, Luigi

2015-03-15

The anti-penicillin G was conjugated to avidin-peroxidase and biotin to obtain immunogen and competitor which were then used to develop a competitive immunosensor assay for the detection of penicillin G and other β-lactam antibiotics, with Kaff values of the order of 10(8) M(-1). The new immunosensor appears to afford a number of advantages in terms of sensitivity, possibility of "in situ" analysis, but especially of simplicity and lower costs, compared with other existing devices, or different chemical instrumental methods reported in the literature and used for the analysis of β-lactam compounds. Satisfactory results were found in the analysis of real matrixes and good recoveries were obtained by applying the standard addition method to spiked milk, urine, serum and drug samples. The new device uses an amperometric electrode for hydrogen peroxide as transducer, the BSA-penicillin G immobilized on polymeric membrane overlapping the amperometric transducer and the peroxidase enzyme as marker. It proved to be highly sensitive, inexpensive and easily reproducible; LOD was of the order of 10(-11)M. Lastly, the new immunosensor displayed low selectivity versus the entire class of β-lactam antibiotics and higher selectivity toward other classes of non-β-lactam antibiotics. Copyright © 2014 Elsevier B.V. All rights reserved.

A sensitive and selective immunoaffinity column clean up coupled to UPLC-MS/MS for determination of trace methyl-3-quinoxaline-2-carboxylic acid in animal tissues.

PubMed

Li, Peipei; Zhang, Xiaojun; Zhang, Juanmei; Yan, Zhongyong; Zhang, Shuai; Chen, Si; Fang, Yi

2018-02-01

This paper described a reliable and simple method for the selective determination of MQCA in animal tissues using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A highly targeted immunoaffinity column was used for sample purification after enzymatic hydrolysis. The purified extracts were analyzed by reversed-phase HPLC-MS/MS in positive ESI and multiple reaction monitoring mode. The calibration curves showed good linearity with correlation coefficient (r 2 ) larger than 0.995. The average recoveries at the spiked levels of 0.5, 2.0 and 20μgkg -1 were 90.2% to 103.5% with intra-day and inter-day relatives standard deviations (RSD, n=6) ranging from 1.8% to 6.7% and 3.5% to 7.6% respectively. The limit of quantification (LOQ) was 0.5μgkg -1 , which can fulfil the maximum residue level (MRL) of 4.0μgkg -1 stipulated by the Agricultural Minister of China and the requirement of the confirmatory criteria according to the European Commission Decision 2002/657/EC. The method is sensitive, accurate, convenient and rapid, and has been successfully applied in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Bacteriophage-fused peptides for serodiagnosis of human strongyloidiasis.

PubMed

Feliciano, Nágilla Daliane; Ribeiro, Vanessa da Silva; Santos, Fabiana de Almeida Araújo; Fujimura, Patricia Tiemi; Gonzaga, Henrique Tomaz; Goulart, Luiz Ricardo; Costa-Cruz, Julia Maria

2014-01-01

Strongyloidiasis, a human intestinal infection caused by the nematode Strongyloides stercoralis, is frequently underdiagnosed and although its high prevalence is still a neglected parasitic disease because conventional diagnostic tests based on parasitological examination (presence of Strongyloides larvae in stool) are not sufficiently sensitive due to the low parasitic load and to the irregular larval output. There is an urgent need to improve diagnostic assays, especially for immunocompromised patients with high parasitic load as consequence of self-infection cycle, which can disseminate throughout the body, resulting in a potentially fatal hyperinfection syndrome often accompanied by sepsis or meningitis. We have performed Phage Display technology to select peptides that mimic S. stercoralis antigens, capable of detecting a humoral response in patients with strongyloidiasis. The peptides reactivity was investigated by Phage-ELISA through different panels of serum samples. We have successfully selected five peptides with significant immunoreactivity to circulating IgG from patients' sera with strongyloidiasis. The phage displayed peptides C9 and C10 presented the highest diagnostic potential (AUC>0.87) with excellent sensitivity (>85%) and good specificity (>77.5%), suggesting that some S. stercoralis antigens trigger systemic immune response. These novel antigens are interesting serum biomarkers for routine strongyloidiasis screenings due to the easy production and simple assay using Phage-ELISA. Such markers may also present a promising application for therapeutic monitoring.

Metal-Free Cataluminescence Gas Sensor for Hydrogen Sulfide Based on Its Catalytic Oxidation on Silicon Carbide Nanocages.

PubMed

Wu, Liqian; Zhang, Lichun; Sun, Mingxia; Liu, Rui; Yu, Lingzhu; Lv, Yi

2017-12-19

Cataluminescence- (CTL-) based sensors are among the most attractive and effective tools for gas sensing, owing to their efficient selectivity, high sensitivity, and rapidity. As the sensing materials of CTL-based sensors, metal-based catalysts easily bring about high costs and environmental pollution of heavy metals. More importantly, the long-term stability of metal-based catalysts is usually rather poor. Metal-free catalysts have unique advantages such as environmental friendliness, low costs, and long-term stability, making them promising materials for CTL-based sensors. Herein, we report the fabrication of a CTL sensor based on a metal-free catalyst. F-doped cage-like SiC was synthesized by wet chemical etching. The as-prepared products showed a rapid, stable, highly selective, and sensitive cataluminescent response to H 2 S. The stability of the sensor was demonstrated to be fairly good for at least 15 days. After CTL tests, F-doped cage-like SiC retained its original morphology, structure, and chemical composition. In addition, to the best of our knowledge, this is the first report of a metal-free CTL sensor. Metal-free catalysts are environmentally friendly and low in cost and exhibit long-term stability, which could open a new avenue of CTL sensing.

Amorphous Ni(OH)2/CQDs microspheres for highly sensitive non-enzymatic glucose detection prepared via CQDs induced aggregation process

NASA Astrophysics Data System (ADS)

Zhu, Jiajie; Yin, Haoyong; Cui, Zhenzhen; Qin, Dongyu; Gong, Jianying; Nie, Qiulin

2017-10-01

Non-enzymatic electrochemical sensors for the detection of glucose were designed based on amorphous Ni(OH)2/CQDs microspheres. The amorphous Ni(OH)2/CQDs microspheres were prepared by a CQDs assistant crystallization inhibition process. The morphologies and composition of the microspheres were characterized by SEM, TEM, XRD, EDS, and TG/DSC. The results showed that the microspheres had uniform heterogeneous phases with amorphous Ni(OH)2 and CQDs. The sensor based on amorphous Ni(OH)2/CQDs microspheres showed remarkable electrocatalytic activity towards glucose oxidation comparing to the conventional crystalline Ni(OH)2, which included two linear range (20 μM-350 μM and 0.45mM-2.5 mM) with high selectivity of 2760.05 and 1853.64 μA mM-1cm-2. Moreover, the interference from the commonly interfering species such as urea, ascorbic acid, NaCl, L-proline and L-Valine, can be effectively avoided. The high sensitivity, wide glucose detection range and good selectivity of the electrode may be due to their synergistic effect of amorphous phase and CQDs incorporation. These findings may promote the application of amorphous Ni(OH)2 as advanced electrochemical glucose sensing materials.

Comparison of different screening methods for blood pressure disorders in children and adolescents.

PubMed

Mourato, Felipe Alves; Lima Filho, José Luiz; Mattos, Sandra da Silva

2015-01-01

To compare different methods of screening for blood pressure disorders in children and adolescents. A database with 17,083 medical records of patients from a pediatric cardiology clinic was used. After analyzing the inclusion and exclusion criteria, 5,650 were selected. These were divided into two age groups: between 5 and 13 years and between 13 and 18 years. The blood pressure measurement was classified as normal, pre-hypertensive, or hypertensive, consistent with recent guidelines and the selected screening methods. Sensitivity, specificity, and accuracy were then calculated according to gender and age range. The formulas proposed by Somu and Ardissino's table showed low sensitivity in identifying pre-hypertension in all age groups, whereas the table proposed by Kaelber showed the best results. The ratio between blood pressure and height showed low specificity in the younger age group, but showed good performance in adolescents. Screening tools used for the assessment of blood pressure disorders in children and adolescents may be useful to decrease the current rate of underdiagnosis of this condition. The table proposed by Kaelber showed the best results; however, the ratio between BP and height demonstrated specific advantages, as it does not require tables. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

Development of Ion Chemosensors Based on Porphyrin Analogues.

PubMed

Ding, Yubin; Zhu, Wei-Hong; Xie, Yongshu

2017-02-22

Sensing of metal ions and anions is of great importance because of their widespread distribution in environmental systems and biological processes. Colorimetric and fluorescent chemosensors based on organic molecular species have been demonstrated to be effective for the detection of various ions and possess the significant advantages of low cost, high sensitivity, and convenient implementation. Of the available classes of organic molecules, porphyrin analogues possess inherently many advantageous features, making them suitable for the design of ion chemosensors, with the targeted sensing behavior achieved and easily modulated based on their following characteristics: (1) NH moieties properly disposed for binding of anions through cooperative hydrogen-bonding interactions; (2) multiple pyrrolic N atoms or other heteroatoms for selectively chelating metal ions; (3) variability of macrocycle size and peripheral substitution for modulation of ion selectivity and sensitivity; and (4) tunable near-infrared emission and good biocompatibility. In this Review, design strategies, sensing mechanisms, and sensing performance of ion chemosensors based on porphyrin analogues are described by use of extensive examples. Ion chemosensors based on normal porphyrins and linear oligopyrroles are also briefly described. This Review provides valuable information for researchers of related areas and thus may inspire the development of more practical and effective approaches for designing high-performance ion chemosensors based on porphyrin analogues and other relevant compounds.

A NBD-based simple but effective fluorescent pH probe for imaging of lysosomes in living cells.

PubMed

Cao, Xiang-Jian; Chen, Li-Na; Zhang, Xuan; Liu, Jin-Ting; Chen, Ming-Yu; Wu, Qiu-Rong; Miao, Jun-Ying; Zhao, Bao-Xiang

2016-05-12

NBDlyso with lysosome-locating morpholine moiety has been developed as a high selective and sensitive fluorescent pH probe. This probe can respond to acidic pH (2.0-7.0) in a short time (less than 1 min) and not almost change after continuously illuminated for an extended period by ultraviolet light. The fluorescence intensity of NBDlyso enhanced 100-fold in acidic solution, with very good linear relationship (R(2) = 0.996). The pKa of probe NBDlyso is 4.10. Therefore, NBDlyso was used to detect lysosomal pH changes successfully. Besides, X-ray crystallography was used to verify the structure of NBDlyso, and the recognition mechanism involving photo-induced electron transfer was interpreted theoretically by means of DFT and TDDFT calculations skillfully when NBDlyso comes into play under the acidic condition. This probe showed good ability to sense pH change in living cell image. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative study of two negative CAR resists: EN-024M and NEB 31

NASA Astrophysics Data System (ADS)

Baik, Ki-Ho; Dean, Robert; Lem, Homer Y.; Osborne, Stephen P.; Mueller, Mark A.; Cole, Damon M.

2004-08-01

In this paper, two negative-tone chemically amplified resists (CAR) are evaluated. The methodology and results are compared and discussed. The resists include EN-024M from TOK, and NEB 31 from Sumitomo. Both resists show high contrast, good dry etch selectivity, and high environmental stability. EN-024M showed good coating uniformity while NEB31 showed a coating uniformity problem. This was a round "dimple" approximately one centimeter in diameter of different thickness and density at the center of the plate. We addressed the "dimple" coating problem as described in the paper. Optimum PAB and PEB temperatures and nominal to maximum doses for isolated features were determined by running a matrix of PAB and PEB temperatures along with a dose series. We evaluated the process and compared the lithographic performance in terms of dose sensitivity, dose and bake latitude, resolution, resist profile, OPC (Optical Proximity Correction) pattern fidelity, CD uniformity, environmental stability, Line Edge Roughness (LER) and etching bias and resistance.

Preparation and characterization of monoclonal antibody against digoxin.

PubMed

Kashanian, S; Rasaee, M J; Paknejad, M; Omidfar, K; Pour-Amir, M; Rajabi, Bazl M

2002-10-01

Mouse-mouse hybridoma cell lines producing stable, highly specific and with good affinity monoclonal antibody (MAb) against the cardiac glycoside digoxin were established. Balb/c mice were immunized via injection of digoxin-3'-bovine serum albumin (BSA). The spleens of which were fused with myeloma cells of SP2/0 origin. Three clones designated as BBA, MBE, and BMG producing good antibodies displayed different patterns of fine specificity for digoxin and low cross-reaction with several digoxin analogues as elucidated by inhibition enzyme-linked immunosorbant assay (ELISA). All three MAbs were of the same class and subclass (IgG(1)). Affinity purification was performed for the selected clone BBA displaying the highest affinity and nearly no cross-reactivity with any of the structurally related molecules. Ultrafiltered concentrated hybrid cell supernatant was also purified by polyethylene glycol (PEG) 6000 precipitation for large-scale preparation and coated onto the wells of microtiter plates. The standard curve was constructed with a sensitivity of 10 pg/well covering up to 10 ng/well.

A voltammetric determination of caffeic acid in red wines based on the nitrogen doped carbon modified glassy carbon electrode.

PubMed

Karikalan, Natarajan; Karthik, Raj; Chen, Shen-Ming; Chen, Hsi-An

2017-04-05

We reported an electrochemical determination of caffeic acid (CA) based on the nitrogen doped carbon (NDC). The described sensor material was prepared by the flame synthesis method, which gave an excellent platform for the synthesis of carbon nanomaterials with the hetero atom dopant. The synthesized material was confirmed by various physical characterizations and it was further characterized by different electrochemical experiments. The NDC modified glassy carbon electrode (NDC/GCE) shows the superior electrocatalytic performance towards the determination of CA with the wide linear concentration range from 0.01 to 350 μM. It achieves the lowest detection limit of 0.0024 μM and the limit of quantification of 0.004 μM. The NDC/GCE-CA sensor reveals the good selectivity, stability, sensitivity and reproducibility which endorsed that the NDC is promising electrode for the determination of CA. In addition, NDC modified electrode is applied to the determination of CA in red wines and acquired good results.

Electrochemistry of raloxifene on glassy carbon electrode and its determination in pharmaceutical formulations and human plasma.

PubMed

Bagheri, Akbar; Hosseini, Hadi

2012-12-01

The electrochemical behavior of raloxifene (RLX) on the surface of a glassy carbon electrode (GCE) has been studied by cyclic voltammetry (CV). The CV studies were performed in various supporting electrolytes, wide range of potential scan rates, and pHs. The results showed an adsorption-controlled and quasi-reversible process for the electrochemical reaction of RLX, and a probable redox mechanism was suggested. Under the optimum conditions, differential pulse voltammetry (DPV) was applied for quantitative determination of the RLX in pharmaceutical formulations. The DPV measurements showed that the anodic peak current of the RLX was linear to its concentration in the range of 0.2-50.0μM with a detection limit of 0.0750μM, relative standard deviation (RSD %) below 3.0%, and a good sensitivity. The proposed method was successfully applied for determination of the RLX in pharmaceutical and human plasma samples with a good selectivity and suitable recovery. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis and characterization of novel 2, 2'-bipyrimidine fluorescent derivative for protein binding

PubMed Central

2011-01-01

Background Fluorescent dyes with biocompatible functional group and good fluorescence behavior are used as biosensor for monitoring different biological processes as well as detection of protein assay. All reported fluorophore used as sensors are having high selectivity and sensitivity but till there is more demand to synthesized new fluorophore which have improved fluorescence properties and good biocompatibility. Results Novel 4, 4'-(1, 1'-(5-(2-methoxyphenoxy)-[2, 2'-bipyrimidine]-4, 6-diyl)bis(1H-pyrazol-3, 1-diyl)) dianiline fluorescent dye was synthesized by multistep synthesis from 2-phenylacetonitrile, 2-chloropyrimidine and 2-methoxyphenol. This dye has absorption at 379 nm with intense single emission at 497 nm having fairly good quantum yield (0.375) and Stokes shift. The intermediates and dye were characterized by FT-IR, 1H NMR, 13C NMR and Mass spectral analysis. The pyrazole bipyrimidine based fluorescent dye possessing two amino groups suitable for binding with protein is reported. Its utility as a biocompatible conjugate was explained by conjugation with bovine serum albumin. The method is based on direct fluorescence detection of fluorophore-labelled protein before and after conjugation. Purified fluorescent conjugate was subsequently analyzed by fluorimetry. The analysis showed that the tested conjugation reaction yielded fluorescent conjugates of the dye through carbodiimide chemistry. Conclusion In summery synthesized fluorophore pyrazole-bipyrimidine has very good interaction towards protein bovine serum albumin and it acts as good candidate for protein assay. PMID:22067202

Considerations in high-resolution skeletal muscle diffusion tensor imaging using single-shot echo planar imaging with stimulated-echo preparation and sensitivity encoding.

PubMed

Karampinos, Dimitrios C; Banerjee, Suchandrima; King, Kevin F; Link, Thomas M; Majumdar, Sharmila

2012-05-01

Previous studies have shown that skeletal muscle diffusion tensor imaging (DTI) can noninvasively probe changes in the muscle fiber architecture and microstructure in diseased and damaged muscles. However, DTI fiber reconstruction in small muscles and in muscle regions close to aponeuroses and tendons remains challenging because of partial volume effects. Increasing the spatial resolution of skeletal muscle single-shot diffusion-weighted echo planar imaging (DW-EPI) can be hindered by the inherently low signal-to-noise ratio (SNR) of muscle DW-EPI because of the short muscle T(2) and the high sensitivity of single-shot EPI to off-resonance effects and T(2)* blurring. In this article, eddy current-compensated diffusion-weighted stimulated-echo preparation is combined with sensitivity encoding (SENSE) to maintain good SNR properties and to reduce the sensitivity to distortions and T(2)* blurring in high-resolution skeletal muscle single-shot DW-EPI. An analytical framework is developed to optimize the reduction factor and diffusion weighting time to achieve maximum SNR. Arguments for the selection of the experimental parameters are then presented considering the compromise between SNR, B(0)-induced distortions, T(2)* blurring effects and tissue incoherent motion effects. On the basis of the selected parameters in a high-resolution skeletal muscle single-shot DW-EPI protocol, imaging protocols at lower acquisition matrix sizes are defined with matched bandwidth in the phase-encoding direction and SNR. In  vivo results show that high-resolution skeletal muscle DTI with minimized sensitivity to geometric distortions and T(2)* blurring is feasible using the proposed methodology. In particular, a significant benefit is demonstrated from a reduction in partial volume effects for resolving multi-pennate muscles and muscles with small cross-sections in calf muscle DTI. Copyright © 2011 John Wiley & Sons, Ltd.

Development and comparative investigation of Ag-sensitive layer based SAW and QCM sensors for mercury sensing applications.

PubMed

Kabir, K M Mohibul; Sabri, Ylias M; Kandjani, Ahmad Esmaielzadeh; Ippolito, Samuel J; Bhargava, Suresh K

2016-04-21

Piezoelectric acoustic wave devices integrated with noble metal surfaces provide exciting prospects for the direct measurement of toxic gas species such as mercury (Hg) in the atmosphere. Even though gold (Au) based acoustic wave sensors have been utilized extensively for detecting Hg, the potential of using other metal surfaces such as silver (Ag) is yet to be thoroughly studied. Here, we developed Ag sensitive layer-based surface acoustic wave (SAW) and quartz crystal microbalance (QCM) sensors and focused on their comparative analysis for Hg sensing applications with parameters such as the sensor sensitivity, selectivity, adsorption/desorption isotherm and Hg diffusion into the surface thoroughly studied. The SAW sensor was fabricated with nickel (Ni) interdigitated transducer (IDT) electrodes and a Ag thin film on the delay line of the device. In the case of the QCM sensor, the electrodes were constructed of Ag thin film and simultaneously employed as a sensitive layer. Mercury sensing experiments were conducted for a range of concentrations between 24-365 ppbv without/with the presence of some common industrial interfering gas species (i.e. ammonia, acetaldehyde, ethyl mercaptan, dimethyl disulphide, methyl ethyl ketone and humidity) at various operating temperatures in the range of 35-95 °C. The SAW sensor was found to possess up to 70 times higher response magnitudes than its QCM counterpart at 35 °C while up to 30 and 23 times higher response magnitudes were observed for the SAW sensor at elevated temperatures of 75 and 95 °C, respectively. Furthermore, the SAW sensor showed good selectivity (>89%) toward Hg(0) vapor in the presence of all the interferents tested at an operating temperature of 75 °C while the QCM sensor exhibited significant cross-sensitivity when ethyl mercaptan was introduced along with Hg(0) vapor. Overall, it is indicative that Ag-based acoustic wave sensors do have great potential for Hg sensing applications, given that right operating conditions are applied.

Vessel-wall imaging and quantification of flow-mediated dilation using water-selective 3D SSFP-echo.

PubMed

Langham, Michael C; Li, Cheng; Englund, Erin K; Chirico, Erica N; Mohler, Emile R; Floyd, Thomas F; Wehrli, Felix W

2013-10-30

To introduce a new, efficient method for vessel-wall imaging of carotid and peripheral arteries by means of a flow-sensitive 3D water-selective SSFP-echo pulse sequence. Periodic applications of RF pulses will generate two transverse steady states, immediately after and before an RF pulse; the latter being referred to as the SSFP-echo. The SSFP-echo signal for water protons in blood is spoiled as a result of moving spins losing phase coherence in the presence of a gradient pulse along the flow direction. Bloch equation simulations were performed over a wide range of velocities to evaluate the flow sensitivity of the SSFP-echo signal. Vessel walls of carotid and femoral and popliteal arteries were imaged at 3 T. In two patients with peripheral artery disease the femoral arteries were imaged bilaterally to demonstrate method's potential to visualize atherosclerotic plaques. The method was also evaluated as a means to measure femoral artery flow-mediated dilation (FMD) in response to cuff-induced ischemia in four subjects. The SSFP-echo pulse sequence, which does not have a dedicated blood signal suppression preparation, achieved low blood signal permitting discrimination of the carotid and peripheral arterial walls with in-plane spatial resolution ranging from 0.5 to 0.69 mm and slice thickness of 2 to 3 mm, i.e. comparable to conventional 2D vessel-wall imaging techniques. The results of the simulations were in good agreement with analytical solution and observations for both vascular territories examined. Scan time ranged from 2.5 to 5 s per slice yielding a contrast-to-noise ratio between the vessel wall and lumen from 3.5 to 17. Mean femoral FMD in the four subjects was 9%, in good qualitative agreement with literature values. Water-selective 3D SSFP-echo pulse sequence is a potential alternative to 2D vessel-wall imaging. The proposed method is fast, robust, applicable to a wide range of flow velocities, and straightforward to implement.

Development and validation of an ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method for the simultaneous determination of selected flavonoids in Ginkgo biloba.

PubMed

Pandey, Renu; Chandra, Preeti; Arya, Kamal Ram; Kumar, Brijesh

2014-12-01

A rapid and sensitive ultra high performance liquid chromatography electrospray ionization tandem mass spectrometry method was developed and validated for the simultaneous determination of 13 flavonoids in leaf, stem, and fruit extracts of male and female trees of Ginkgo biloba to investigate gender- and age-related variations of flavonoids content. Chromatographic separation was accomplished on an Acquity UPLC BEH C18 column (50 mm × 2.1 mm id, 1.7 μm) in 5 min. Quantitation was performed using negative electrospray ionization mass spectrometry in multiple reaction monitoring mode. The calibration curves of all analytes showed a good linear relationship (r(2) ≥ 0.9977) over the concentration range of 1-1000 ng/mL. The precision evaluated by an intra- and interday study showed RSD ≤ 1.98% and good accuracy with overall recovery in the range from 97.90 to 101.09% (RSD ≤ 1.67%) for all analytes. The method sensitivity expressed as the limit of quantitation was typically 0.25-3.57 ng/mL. The results showed that the total content of 13 flavonoids was higher in the leaf extract of an old male Ginkgo tree compared to young female Ginkgo trees. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modeling guided wave excitation in plates with surface mounted piezoelectric elements: coupled physics and normal mode expansion

NASA Astrophysics Data System (ADS)

Ren, Baiyang; Lissenden, Cliff J.

2018-04-01

Guided waves have been extensively studied and widely used for structural health monitoring because of their large volumetric coverage and good sensitivity to defects. Effectively and preferentially exciting a desired wave mode having good sensitivity to a certain defect is of great practical importance. Piezoelectric discs and plates are the most common types of surface-mounted transducers for guided wave excitation and reception. Their geometry strongly influences the proportioning between excited modes as well as the total power of the excited modes. It is highly desirable to predominantly excite the selected mode while the total transduction power is maximized. In this work, a fully coupled multi-physics finite element analysis, which incorporates the driving circuit, the piezoelectric element and the wave guide, is combined with the normal mode expansion method to study both the mode tuning and total wave power. The excitation of circular crested waves in an aluminum plate with circular piezoelectric discs is numerically studied for different disc and adhesive thicknesses. Additionally, the excitation of plane waves in an aluminum plate, using a stripe piezoelectric element is studied both numerically and experimentally. It is difficult to achieve predominant single mode excitation as well as maximum power transmission simultaneously, especially for higher order modes. However, guidelines for designing the geometry of piezoelectric elements for optimal mode excitation are recommended.

Theoretical Insight into the Influences of Molecular Ratios on Stabilities and Mechanical Properties, Solvent Effect of HMX/FOX-7 Cocrystal Explosive

NASA Astrophysics Data System (ADS)

Wei, Yan-Ju; Ren, Fu-De; Shi, Wen-Jing; Zhao, Qi

2016-10-01

A molecular dynamics method was employed to study the binding energies of the selected crystal planes of the 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane/1,1-diamino-2,2-dinitroethylene (HMX/FOX-7) cocrystal in different molecular molar ratios. Mechanical properties, densities, and detonation velocities of the cocrystals in different ratios were estimated. The intermolecular interactions and bond dissociation energies (BDEs) of the N-NO2 bond in the HMX:FOX-7 (1:1) complex were calculated using the B3LYP and MP2(full) methods at the 6-311++G (d,p) and 6-311++G(2df,2p) basis sets. Solvent effects on stability are discussed. The results indicate that HMX/FOX-7 cocrystals prefer cocrystalizing in a 1:1 molar ratio, which has good mechanical properties. The N-NO2 bond becomes strong upon the formation of a complex and the sensitivity of HMX might decrease in cocrystals. The sensitivity change of HMX/FOX-7 originates from not only the formation of intermolecular interaction but also the increment in the N-NO2 BDE. HMX/FOX-7 cocrystals exhibit good detonation performance and meet the requirements of high-density energetic materials. Solvents with low dielectric constants may be chosen to obtain stable HMX/FOX-7 cocrystals.

Sensitive determination of trace mercury by UV-visible diffuse reflectance spectroscopy after complexation and membrane filtration-enrichment.

PubMed

Yin, Changhai; Iqbal, Jibran; Hu, Huilian; Liu, Bingxiang; Zhang, Lei; Zhu, Bilin; Du, Yiping

2012-09-30

A simple, sensitive and selective solid phase reflectometry method is proposed for the determination of trace mercury in aqueous samples. The complexation reagent dithizone was firstly injected into the properly buffered solution with vigorous stirring, which started a simultaneous formation of nanoparticles suspension of dithizone and its complexation reaction with the mercury(II) ions to make Hg-dithizone nanoparticles. After a definite time, the mixture was filtered with membrane, and then quantified directly on the surface of the membrane by using integrating sphere accessory of the UV-visible spectrophotometer. The quantitative analysis was carried out at a wavelength of 485 nm since it yielded the largest difference in diffuse reflectance spectra before and after reaction with mercury(II).A good linear correlation in the range of 0.2-4.0 μg/L with a squared correlation coefficient (R(2)) of 0.9944 and a detection limit of 0.12 μg/L were obtained. The accuracy of the method was evaluated by the analysis of spiked mercury(II) concentrations determined using this method along with those determined by the atomic fluorescence mercury vapourmeter and the results obtained were in good agreement. The proposed method was applied to the determination of mercury in tap water and river water samples with the recovery in an acceptable range (95.7-105.3%). Copyright © 2012 Elsevier B.V. All rights reserved.

Amperometric immunosensor for α-fetoprotein antigen in human serum based on co-immobilizing dinuclear copper complex and gold nanoparticle doped chitosan film

NASA Astrophysics Data System (ADS)

Gan, Ning; Meng, Ling Hua; Wang, Feng

2009-09-01

A sensitive amperometric immunosensor for α-fetoprotein (AFP), a tumor marker for the diagnosis of hepatocellular carcinoma (HCC), was constructed, The immunosensor is prepared by co-immobilizing [Cu2(phen)2Cl2] (μ-Cl)2 (CuL), nano-Au/Chitosan(Chit) composite, horseradish peroxidase (HRP) and AFP antibody(anti-AFP) on a glassy carbon electrode (GCE). Firstly, CuL was irreversibly absorb on GCE electrode through π-π stacking interaction; then nano-Au/Chit composite was immobilized onto the electrode because of its excellent membrane-forming ability, finally HRP and anti-AFP was adsorbed onto the surface of the gold nanoparticles to construct GCE | CuL/nanoAu-chit/HRP/anti-AFP immunosensor. The preparation procedure of the electrode was characterized by electrochemical and spectroscopy method. The results showed that this immunosensor exhibited an excellent electrocatalytic response to the reduction of hydrogen peroxide (H2O2) without the aid of an electron mediator, offers a high-sensitivity (1710 nA · ng-1 · ml-1) for the detection of AFP and has good correlation for detection of AFP in the range of 0.2 to 120.0 ng/ml with a detection limit of 0.05 ng/ml. The biosensor showed high selectivity as well as good stability and reproductivity.

The Development of Non-Enzymatic Glucose Biosensors Based on Electrochemically Prepared Polypyrrole–Chitosan–Titanium Dioxide Nanocomposite Films

PubMed Central

AL-Mokaram, Ali M. A. Abdul Amir; Yahya, Rosiyah; Abdi, Mahnaz M.; Mahmud, Habibun Nabi Muhammad Ekramul

2017-01-01

The performance of a modified electrode of nanocomposite films consisting of polypyrrole–chitosan–titanium dioxide (Ppy-CS-TiO2) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO2 nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO2 NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO2 in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1–14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO2 nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell. PMID:28561760

Electrochemical immunosensor with nanocellulose-Au composite assisted multiple signal amplification for detection of avian leukosis virus subgroup J.

PubMed

Liu, Chao; Dong, Jing; Waterhouse, Geoffrey I N; Cheng, Ziqiang; Ai, Shiyun

2018-03-15

A sensitive sandwich-type electrochemical immunosensor was developed for the detection of avian leukosis virus subgroup J (ALV-J), which benefitted from multiple signal amplification involving graphene-perylene-3,4,9,10-tetracarboxylic acid nanocomposites (GR-PTCA), nanocellulose-Au NP composites (NC-Au) and the alkaline phosphatase (ALP) catalytic reaction. GR-PTCA nanocomposites on glassy carbon electrodes served as the immunosensor platform. Due to their excellent electrical conductivity and abundant polycarboxylic sites, the GR-PTCA nanocomposites allowed fast electron transfer and good immobilization of primary antibodies, thereby affording a strong immunosensor signal in the presence of ALV-J. The detected signal could be further amplified by the introduction of NC-Au composites as a carrier of secondary antibodies (Ab 2 ) and by harnessing the catalytic properties of Au and ALP. Under optimized testing conditions, the electrochemical immunosensor displayed excellent analytical performance for the detection of ALV-J, showing a linear current response from 10 2.08 to 10 4.0 TCID 50 /mL (TCID 50 : 50% tissue culture infective dose) with a low detection limit of 10 1.98 TCID 50 /mL (S/N = 3). In addition to high sensitivity, the immunosensor showed very good selectivity, reproducibility and operational stability, demonstrating potential application for the quantitative detection of ALV-J in clinical diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

[1]Benzothieno[3,2-b]benzothiophene-Based Organic Dyes for Dye-Sensitized Solar Cells.

PubMed

Capodilupo, Agostina L; Fabiano, Eduardo; De Marco, Luisa; Ciccarella, Giuseppe; Gigli, Giuseppe; Martinelli, Carmela; Cardone, Antonio

2016-04-15

Three new metal-free organic dyes with the [1]benzothieno[3,2-b]benzothiophene (BTBT) π-bridge, having the structure donor-π-acceptor (D-π-A) and labeled as 19, 20 and 21, have been designed and synthesized for application in dye-sensitized solar cells (DSSC). Once the design of the π-acceptor block was fixed, containing the BTBT as the π-bridge and the cyanoacrylic group as the electron acceptor and anchoring unit, we selected three donor units with different electron-donor capacity, in order to assemble new chromophores with high molar extinction coefficients (ε), whose absorption features well reflect the good performance of the final DSSC devices. Starting with the 19 dye, which shows a molar extinction coefficient ε of over 14,000 M(-1) cm(-1) and takes into account the absorption maximun at the longer wavelength, the substitution of the BFT donor unit with the BFA yields a great enhancement of absorptivity (molar extinction coefficient ε > 42,000 M(-1) cm(-1)), until reaching the higher value (ε > 69,000 M(-1) cm(-1)) with the BFPhz donor unit. The good general photovoltaic performances obtained with the three dyes highlight the suitable properties of electron-transport of the BTBT as the π-bridge in organic chromophore for DSSC, making this very cheap and easy to synthesize molecule particularly attractive for efficient and low-cost photovoltaic devices.

New solid surface fluorescence methodology for lead traces determination using rhodamine B as fluorophore and coacervation scheme: Application to lead quantification in e-cigarette refill liquids.

PubMed

Talio, María C; Zambrano, Karen; Kaplan, Marcos; Acosta, Mariano; Gil, Raúl A; Luconi, Marta O; Fernández, Liliana P

2015-10-01

A new environmental friendly methodology based on fluorescent signal enhancement of rhodamine B dye is proposed for Pb(II) traces quantification using a preconcentration step based on the coacervation phenomenon. A cationic surfactant (cetyltrimethylammonium bromide, CTAB) and potassium iodine were chosen for this aim. The coacervate phase was collected on a filter paper disk and the solid surface fluorescence signal was determined in a spectrofluorometer. Experimental variables that influence on preconcentration step and fluorimetric sensitivity have been optimized using uni-variation assays. The calibration graph using zero th order regression was linear from 7.4×10(-4) to 3.4 μg L(-1) with a correlation coefficient of 0.999. Under the optimal conditions, a limit of detection of 2.2×10(-4) μg L(-1) and a limit of quantification of 7.4×10(-4) μg L(-1) were obtained. The method showed good sensitivity, adequate selectivity with good tolerance to foreign ions, and was applied to the determination of trace amounts of Pb(II) in refill solutions for e-cigarettes with satisfactory results validated by ICP-MS. The proposed method represents an innovative application of coacervation processes and of paper filters to solid surface fluorescence methodology. Copyright © 2015 Elsevier B.V. All rights reserved.

Student perceptions of a good teacher: the gender perspective.

PubMed

Jules, V; Kutnick, P

1997-12-01

A large-scale survey of pupils' perceptions of a good teacher in the Caribbean republic of Trinidad and Tobago is reported. An essay-based, interpretative mode of research was used to elicit and identify constructs used by boys and girls. The study explores similarities and differences between boys and girls in their perceptions of a good teacher, in a society where girls achieve superior academic performance (than boys). A total of 1756 pupils and students aged between 8 and 16 provided the sample, which was proportional, stratified, clustered. Within these constraints classrooms were randomly selected to be representative of primary and secondary schools across the two islands. Altogether 1539 essays and 217 interviews were content analysed, coded for age development and compared between boys and girls. Content items identified by the pupils were logically grouped into: physical and personal characteristics of the teacher, quality of the relationship between the teacher and pupil, control of behaviour by the teacher, descriptions of the teaching process, and educational and other outcomes obtained by pupils due to teacher efforts. Female pupils identified more good teacher concepts at all age levels than males. There was some commonality between the sexes in concepts regarding interpersonal relationships and inclusiveness in the good teachers' teaching practices and boys showed significantly greater concerns regarding teacher control and use of punishment. Males as young as 8 years stated that good teachers should be sensitive to their needs. Only among the 16-year-old males were males noted as good teachers. Consideration is given to the roles of male and female teachers, how their classroom actions may set the basis for future success (or failure) of their pupils, and the needs of pupils with regard to teacher support within developing and developed countries.

Health care for immigrants in Europe: Is there still consensus among country experts about principles of good practice? A Delphi study

PubMed Central

2011-01-01

Background European Member States are facing a challenge to provide accessible and effective health care services for immigrants. It remains unclear how best to achieve this and what characterises good practice in increasingly multicultural societies across Europe. This study assessed the views and values of professionals working in different health care contexts and in different European countries as to what constitutes good practice in health care for immigrants. Methods A total of 134 experts in 16 EU Member States participated in a three-round Delphi process. The experts represented four different fields: academia, Non-Governmental Organisations, policy-making and health care practice. For each country, the process aimed to produce a national consensus list of the most important factors characterising good practice in health care for migrants. Results The scoring procedures resulted in 10 to 16 factors being identified as the most important for each participating country. All 186 factors were aggregated into 9 themes: (1) easy and equal access to health care, (2) empowerment of migrants, (3) culturally sensitive health care services, (4) quality of care, (5) patient/health care provider communication, (6) respect towards migrants, (7) networking in and outside health services, (8) targeted outreach activities, and (9) availability of data about specificities in migrant health care and prevention. Although local political debate, level of immigration and the nature of local health care systems influenced the selection and rating of factors within each country, there was a broad European consensus on most factors. Yet, discordance remained both within countries, e.g. on the need for prioritising cultural differences, and between countries, e.g. on the need for more consistent governance of health care services for immigrants. Conclusions Experts across Europe asserted the right to culturally sensitive health care for all immigrants. There is a broad consensus among experts about the major principles of good practice that need to be implemented across Europe. However, there also is some disagreement both within and between countries on specific issues that require further research and debate. PMID:21914194

Fluorescent trimethyl-substituted naphthyridine as a label-free signal reporter for one-step and highly sensitive fluorescent detection of DNA in serum samples.

PubMed

Wang, Jiamian; Wang, Xiuyun; Wu, Shuo; Che, Ruping; Luo, Pinchen; Meng, Changgong

2017-01-15

A facile label-free sensing method is developed for the one-step and highly sensitive fluorescent detection of DNA, which couples the specific C-C mismatch bonding and fluorescent quenching property of a trimethyl-substituted naphthyridine dye (ATMND) with the exonuclease III (Exo III) assisted cascade target recycling amplification strategy. In the absence of target DNA, the DNA hairpin probe with a C-C mismatch in the stem and more than 4 bases overhung at the 3' terminus could entrap and quench the fluorescence of ATMND and resist the digestion of Exo III, thus showing a low fluorescence background. In the presence of the target, however, the hybridization event between the two protruding segments and the target triggers the digestion reaction of Exo III, recycles the initial target, and simultaneously releases both the secondary target analogue and the ATMND caged in the stem. The released initial and secondary targets take part in another cycle of digestion, thus leading to the release of a huge amount of free ATMND for signal transducing. Based on the fluorescence recovery, the as-proposed label-free fluorescent sensing strategy shows very good analytical performances towards DNA detection, such as a wide linear range from 10pM to 1μM, a low limit of detection of 6pM, good selectivity, and a facile one-step operation at room temperature. Practical sample analysis in serum samples indicates the method has good precision and accuracy, which may thus have application potentials for point-of-care screening of DNA in complex clinical and environmental samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Climate risk index for Italy.

PubMed

Mysiak, Jaroslav; Torresan, Silvia; Bosello, Francesco; Mistry, Malcolm; Amadio, Mattia; Marzi, Sepehr; Furlan, Elisa; Sperotto, Anna

2018-06-13

We describe a climate risk index that has been developed to inform national climate adaptation planning in Italy and that is further elaborated in this paper. The index supports national authorities in designing adaptation policies and plans, guides the initial problem formulation phase, and identifies administrative areas with higher propensity to being adversely affected by climate change. The index combines (i) climate change-amplified hazards; (ii) high-resolution indicators of exposure of chosen economic, social, natural and built- or manufactured capital (MC) assets and (iii) vulnerability, which comprises both present sensitivity to climate-induced hazards and adaptive capacity. We use standardized anomalies of selected extreme climate indices derived from high-resolution regional climate model simulations of the EURO-CORDEX initiative as proxies of climate change-altered weather and climate-related hazards. The exposure and sensitivity assessment is based on indicators of manufactured, natural, social and economic capital assets exposed to and adversely affected by climate-related hazards. The MC refers to material goods or fixed assets which support the production process (e.g. industrial machines and buildings); Natural Capital comprises natural resources and processes (renewable and non-renewable) producing goods and services for well-being; Social Capital (SC) addressed factors at the individual (people's health, knowledge, skills) and collective (institutional) level (e.g. families, communities, organizations and schools); and Economic Capital (EC) includes owned and traded goods and services. The results of the climate risk analysis are used to rank the subnational administrative and statistical units according to the climate risk challenges, and possibly for financial resource allocation for climate adaptation.This article is part of the theme issue 'Advances in risk assessment for climate change adaptation policy'. © 2018 The Authors.

Climate risk index for Italy

NASA Astrophysics Data System (ADS)

Mysiak, Jaroslav; Torresan, Silvia; Bosello, Francesco; Mistry, Malcolm; Amadio, Mattia; Marzi, Sepehr; Furlan, Elisa; Sperotto, Anna

2018-06-01

We describe a climate risk index that has been developed to inform national climate adaptation planning in Italy and that is further elaborated in this paper. The index supports national authorities in designing adaptation policies and plans, guides the initial problem formulation phase, and identifies administrative areas with higher propensity to being adversely affected by climate change. The index combines (i) climate change-amplified hazards; (ii) high-resolution indicators of exposure of chosen economic, social, natural and built- or manufactured capital (MC) assets and (iii) vulnerability, which comprises both present sensitivity to climate-induced hazards and adaptive capacity. We use standardized anomalies of selected extreme climate indices derived from high-resolution regional climate model simulations of the EURO-CORDEX initiative as proxies of climate change-altered weather and climate-related hazards. The exposure and sensitivity assessment is based on indicators of manufactured, natural, social and economic capital assets exposed to and adversely affected by climate-related hazards. The MC refers to material goods or fixed assets which support the production process (e.g. industrial machines and buildings); Natural Capital comprises natural resources and processes (renewable and non-renewable) producing goods and services for well-being; Social Capital (SC) addressed factors at the individual (people's health, knowledge, skills) and collective (institutional) level (e.g. families, communities, organizations and schools); and Economic Capital (EC) includes owned and traded goods and services. The results of the climate risk analysis are used to rank the subnational administrative and statistical units according to the climate risk challenges, and possibly for financial resource allocation for climate adaptation. This article is part of the theme issue `Advances in risk assessment for climate change adaptation policy'.

Climate risk index for Italy

PubMed Central

Torresan, Silvia; Bosello, Francesco; Mistry, Malcolm; Amadio, Mattia; Marzi, Sepehr; Furlan, Elisa; Sperotto, Anna

2018-01-01

We describe a climate risk index that has been developed to inform national climate adaptation planning in Italy and that is further elaborated in this paper. The index supports national authorities in designing adaptation policies and plans, guides the initial problem formulation phase, and identifies administrative areas with higher propensity to being adversely affected by climate change. The index combines (i) climate change-amplified hazards; (ii) high-resolution indicators of exposure of chosen economic, social, natural and built- or manufactured capital (MC) assets and (iii) vulnerability, which comprises both present sensitivity to climate-induced hazards and adaptive capacity. We use standardized anomalies of selected extreme climate indices derived from high-resolution regional climate model simulations of the EURO-CORDEX initiative as proxies of climate change-altered weather and climate-related hazards. The exposure and sensitivity assessment is based on indicators of manufactured, natural, social and economic capital assets exposed to and adversely affected by climate-related hazards. The MC refers to material goods or fixed assets which support the production process (e.g. industrial machines and buildings); Natural Capital comprises natural resources and processes (renewable and non-renewable) producing goods and services for well-being; Social Capital (SC) addressed factors at the individual (people's health, knowledge, skills) and collective (institutional) level (e.g. families, communities, organizations and schools); and Economic Capital (EC) includes owned and traded goods and services. The results of the climate risk analysis are used to rank the subnational administrative and statistical units according to the climate risk challenges, and possibly for financial resource allocation for climate adaptation. This article is part of the theme issue ‘Advances in risk assessment for climate change adaptation policy’. PMID:29712797

Development of conductometric biosensor array for simultaneous determination of maltose, lactose, sucrose and glucose.

PubMed

Soldatkin, O O; Peshkova, V M; Saiapina, O Y; Kucherenko, I S; Dudchenko, O Y; Melnyk, V G; Vasylenko, O D; Semenycheva, L M; Soldatkin, A P; Dzyadevych, S V

2013-10-15

The aim of this work was to develop an array of biosensors for simultaneous determination of four carbohydrates in solution. Several enzyme systems selective to lactose, maltose, sucrose and glucose were immobilised on the surface of four conductometric transducers and served as bio-recognition elements of the biosensor array. Direct enzyme analysis carried out by the developed biosensors was highly sensitive to the corresponding substrates. The analysis lasted 2 min. The dynamic range of substrate determination extended from 0.001 mM to 1.0-3.0mM, and strongly depended on the enzyme system used. An effect of the solution pH, ionic strength and buffer capacity on the biosensors responses was investigated; the conditions of simultaneous operation of all biosensors were optimised. The data on cross-impact of the substrates of all biosensors were obtained; the biosensor selectivity towards possible interfering carbohydrates was tested. The developed biosensor array showed good signal reproducibility and storage stability. The biosensor array is suited for simultaneous, quick, simple, and selective determination of maltose, lactose, sucrose and glucose. © 2013 Elsevier B.V. All rights reserved.

Safinamide.

PubMed

Fariello, Ruggero G

2007-01-01

Safinamide (SAF) ((S)-(+)-2-(4-(3-fluorobenzyloxy) benzylamino)propanamide) was initially synthetized by Farmitalia Carlo Erba (Italy). Following initial anticonvulsant screening, safinamide was selected for its potency, broad spectrum of action, and good safety margin. Pharmacodynamic properties probably relevant to its antiepileptic activity are use- and frequency-dependent block of voltage sensitive Na+ channels, block of Ca++ channels, and glutamate release inhibition. Possibly contributing mechanism are also selective and reversible monoamide oxidase B inhibition and dopamine and noradrenaline uptake inhibition. The high selectivity for the sigma-1 receptor site does not entail psychotomimetic or behavioral changes. In several experimental in vitro and in vivo conditions, SAF exerts neurorescuing and neuroprotectant effects. Safinamide is water soluble and suitable for 1 times a day oral administration in humans. In a pilot phase II study in 38 refractory epilepsy patients affected by multiple types of seizures, 41% of subjects obtained > or =50% seizure reduction during a 12-week escalating dose up to 300 mg 1 times day compared with perspective baseline. Safinamide is being developed in phase III for treatment of Parkinson's disease, whereas the development in epilepsy relates to the industrial strategy of the company.

Quantitation of cocaine and cocaethylene in small volumes of rat whole blood using gas chromatography-mass spectrometry.

PubMed

Burdick, J D; Boni, R L; Fochtman, F W

1997-05-01

A simple solid phase extraction (SPE) technique combined with gas chromatography-mass spectrometry (GC/MS) operated in selected ion monitoring (SIM) mode is described for quantitation of cocaine and cocaethylene in small samples (250 microliters) of rat whole blood. Use of (N-[2H3C])-cocaine and (N-[2H3C])-cocaethylene internal standards resulted in high sensitivity and selectivity for this analytical method. Analysis was performed using a Hewlett-Packard 5890 GC equipped with a 7673A Automatic Liquid Sampler linked to a Hewlett-Packard 5972 Mass Selective Detector. Separation of analytes was accomplished on a cross-linked methyl silicone gum capillary column (Ultra 1: 12m x 0.2mm (i.d.) x 0.33 microns). Linearity was established over a wide range of concentrations (5.0-2000.0 ng ml-1) with good precision. Limits of detection (LOD) were 1.0 and 2.0 ng ml-1 for cocaine and cocaethylene, respectively. This analytical method was designed for use in pharmacokinetic experiments studying the formation of cocaethylene following ethanol pretreatment in rats administered cocaine.

The Ocean Colour Climate Change Initiative: I. A Methodology for Assessing Atmospheric Correction Processors Based on In-Situ Measurements

NASA Technical Reports Server (NTRS)

Muller, Dagmar; Krasemann, Hajo; Brewin, Robert J. W.; Deschamps, Pierre-Yves; Doerffer, Roland; Fomferra, Norman; Franz, Bryan A.; Grant, Mike G.; Groom, Steve B.; Melin, Frederic;

Quantitative determination of major active components in Ginkgo biloba dietary supplements by liquid chromatography/mass spectrometry.

PubMed

Ding, Shujing; Dudley, Ed; Plummer, Sue; Tang, Jiandong; Newton, Russell P; Brenton, A Gareth

2006-01-01

A reversed-phase high-performance liquid chromatography/electrospray ionisation mass spectrometry (RP-HPLC/ESI-MS) method was developed and validated for the simultaneous determination of ten major active components in Ginkgo biloba extract (bilobalide, ginkgolides A, B, C, quercetin, kaempferol, isorhamnetin, rutin hydrate, quercetin-3-beta-D-glucoside and quercitrin hydrate) which have not been previously reported to be quantified in a single analysis. The ten components exhibit baseline separation in 50 min by C18 chromatography using a water/1:1 (v/v) methanol/acetonitrile gradient. Quantitation was performed using negative ESI-MS in selected ion monitoring (SIM) mode. Good reproducibility and recovery were obtained by this method. The sensitivity of both UV and different mass spectrometry modes (full scan, selected ion monitoring (SIM), and selected reaction monitoring (SRM)) were compared and both quantitation with and without internal standard were evaluated. The analysis of Ginkgo biloba commercial products showed remarkable variations in the rutin and quercetin content as well as the terpene lactone contents although all the products satisfy the conventional quality control method. Copyright 2006 John Wiley & Sons, Ltd.

Selective determination of pyridine alkaloids in tobacco by PFTBA ions/analyte molecule reaction ionization ion trap mass spectrometry.

PubMed

Zhang, Jianxun; Ji, Houwei; Sun, Shihao; Mao, Duobin; Liu, Huwei; Guo, Yinlong

2007-10-01

The application of perfluorotributylamine (PFTBA) ions/analyte molecule reaction ionization for the selective determination of tobacco pyridine alkaloids by ion trap mass spectrometry (IT-MS) is reported. The main three PFTBA ions (CF(3)(+), C(3)F(5)(+), and C(5)F(10)N(+)) are generated in the external source and then introduced into ion trap for reaction with analytes. Because the existence of the tertiary nitrogen atom in the pyridine makes it possible for PFTBA ions to react smoothly with pyridine and forms adduct ions, pyridine alkaloids in tobacco were selectively ionized and formed quasi-molecular ion [M + H](+)and adduct ions, including [M + 69](+), [M + 131](+), and [M + 264](+), in IT-MS. These ions had distinct abundances and were regarded as the diagnostic ions of each tobacco pyridine alkaloid for quantitative analysis in selected-ion monitoring mode. Results show that the limit of detection is 0.2 microg/mL, and the relative standard deviations for the seven alkaloids are in the range of 0.71% to 6.8%, and good recovery of 95.6% and 97.2%. The proposed method provides substantially greater selectivity and sensitivity compared with the conventional approach and offers an alternative approach for analysis of tobacco alkaloids.

Sublethal Toxicity Endpoints of Heavy Metals to the Nematode Caenorhabditis elegans

PubMed Central

Wu, Yue; Wang, Qiang; Li, Huixin

2016-01-01

Caenorhabditis elegans, a free-living nematode, is commonly used as a model organism in ecotoxicological studies. The current literatures have provided useful insight into the relative sensitivity of several endpoints, but few direct comparisons of multiple endpoints under a common set of experimental conditions. The objective of this study was to determine appropriate sublethal endpoints to develop an ecotoxicity screening and monitoring system. C. elegans was applied to explore the sublethal toxicity of four heavy metals (copper, zinc, cadmium and chromium). Two physiological endpoints (growth and reproduction), three behavioral endpoints (head thrash frequency, body bend frequency and feeding) and two enzymatic endpoints (acetylcholine esterase [AChE] and superoxide dismutase [SOD]) were selected for the assessment of heavy metal toxicity. The squared correlation coefficients (R2) between the responses observed and fitted by Logit function were higher than 0.90 and the RMSE were lower than 0.10, indicating a good significance statistically. There was no significant difference among the half effect concentration (EC50) endpoints in physiological and behavioral effects of the four heavy metals, indicating similar sensitivity of physiological and behavioral effects. AChE enzyme was more sensitive to copper, zinc, and cadmium than to other physiological and behavioral effects, and SOD enzyme was most sensitive to chromium. The EC50 of copper, zinc, and cadmium, to the AChE enzyme in the nematodes were 0.68 mg/L, 2.76 mg/L, and 0.92 mg/L respectively and the EC50 of chromium to the SOD enzyme in the nematode was 1.58 mg/L. The results of this study showed that there was a good concentration-response relationship between all four heavy metals and the sublethal toxicity effects to C. elegans. Considering these sublethal endpoints in terms of simplicity, accuracy, repeatability and costs of the experiments, feeding is the relatively ideal sublethal toxicity endpoint of heavy metals to C. elegans. PMID:26824831

Monolithically integrated bacteriorhodopsin/semiconductor opto-electronic integrated circuit for a bio-photoreceiver.

PubMed

Xu, J; Bhattacharya, P; Váró, G

2004-03-15

The light-sensitive protein, bacteriorhodopsin (BR), is monolithically integrated with an InP-based amplifier circuit to realize a novel opto-electronic integrated circuit (OEIC) which performs as a high-speed photoreceiver. The circuit is realized by epitaxial growth of the field-effect transistors, currently used semiconductor device and circuit fabrication techniques, and selective area BR electro-deposition. The integrated photoreceiver has a responsivity of 175 V/W and linear photoresponse, with a dynamic range of 16 dB, with 594 nm photoexcitation. The dynamics of the photochemical cycle of BR has also been modeled and a proposed equivalent circuit simulates the measured BR photoresponse with good agreement.

Human evolutionary genomics: ethical and interpretive issues.

PubMed

Vitti, Joseph J; Cho, Mildred K; Tishkoff, Sarah A; Sabeti, Pardis C

2012-03-01

Genome-wide computational studies can now identify targets of natural selection. The unique information about humans these studies reveal, and the media attention they attract, indicate the need for caution and precision in communicating results. This need is exacerbated by ways in which evolutionary and genetic considerations have been misapplied to support discriminatory policies, by persistent misconceptions of these fields and by the social sensitivity surrounding discussions of racial ancestry. We discuss the foundations, accomplishments and future directions of human evolutionary genomics, attending to ways in which the interpretation of good science can go awry, and offer suggestions for researchers to prevent misapplication of their work. Copyright © 2011 Elsevier Ltd. All rights reserved.

Spectrofluorometric determination of DNA and RNA with berberine

NASA Astrophysics Data System (ADS)

Gong, Guo-Quan; Zong, Zhi-Xin; Song, Yu-Min

1999-08-01

On binding to nucleic acids, the dye berberine increases its fluorescence quantum efficiency by a factor of 25-30. Based on this, an easy, rapid and accurate method for the determination of nucleic acids was developed. Berberine is very like ethidium bromide (EB), but it is non-poisonous. Determination can be made at any pH between 4 and 10, where the native structure of DNA and RNA is not disrupted. The maximum emission is near 520 nm for excitation at 355 or 450 nm. This method has good sensitivity (0.01 μg ml -1 of ctDNA), high selectivity and a wide linear range (0.05-14.0 μg ml -1 of ctDNA).

Polyvinylpyrrolidone/reduced graphene oxide nanocomposites thin films coated on quartz crystal microbalance for NO2 detection at room temperature

NASA Astrophysics Data System (ADS)

Huang, Junlong; Xie, Guangzhong; Zhou, Yong; Xie, Tao; Tai, HuiLing; Yang, Guangjin

2014-08-01

Polyvinylpyrrolidone (PVP)/reduced graphene oxide (RGO) nanocomposites are sprayed on quartz crystal microbalance (QCM) for NO2 sensing. The thin films are characterized by Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-VIS). The experimental results reveal that PVP/RGO sensor exhibits higher sensitivity and shorter recovery time than those of PVP. Besides, the response to 20 ppm NO2 is higher than other gases such as CO, CO2 and NH3 even at 100ppm. When the PVP/RGO sensor is exposed to these gases, the good selectivity to NO2 makes the sensor ideal for NO2 detection.

Enhanced non-enzymatic glucose sensing based on copper nanoparticles decorated nitrogen-doped graphene.

PubMed

Jiang, Ding; Liu, Qian; Wang, Kun; Qian, Jing; Dong, Xiaoya; Yang, Zhenting; Du, Xiaojiao; Qiu, Baijing

2014-04-15

Copper nanoparticles (NPs) decorated nitrogen-doped graphene (Cu-N-G) was prepared by a facile thermal treatment, and further employed as a novel sensing material for fabricating the sensitive non-enzymatic glucose sensor. Compared with pure Cu NPs, the Cu-N-G showed enhanced electrocatalytic activity to glucose oxidation due to the integration of N-G, which exhibited the oxidation peak current of glucose ca. 23-fold higher than that of pure Cu NPs. The presented sensor showed excellent performances for glucose detection including wide linear range of 0.004-4.5 mM, low detection limit (1.3 μM, S/N=3), high sensitivity (48.13 μA mM(-1)), fast response time (<5 s), good selectivity to the general coexisted interferences, etc. Such properties would promote the potential application of the nitrogen-doped graphene as enhanced materials in fabricating sensors for chemical and biochemical analysis. © 2013 Published by Elsevier B.V.

Detection and quantification of microcystins (cyanobacterial hepatotoxins) with recombinant antibody fragments isolated from a naïve human phage display library.

PubMed

McElhiney, J; Lawton, L A; Porter, A J

2000-12-01

Single-chain antibody fragments against the cyanobacterial hepatotoxin microcystin-LR were isolated from a naive human phage display library and expressed in Escherichia coli. In competition enzyme-linked immunosorbent assay (ELISA), the most sensitive antibody clone selected from the library detected free microcystin-LR with an IC(50) value of 4 microM. It was found to cross react with three other microcystin variants - microcystin-RR, microcystin-LW and microcystin-LF - and detected microcystins in extracts of the cyanobacterium Microcystis aeruginosa, found to contain the toxins by high-performance liquid chromatography (HPLC). The quantification of microcystins in these extracts by ELISA and HPLC showed good correlation. Although the antibody isolated in this study was considerably less sensitive than the polyclonal and monoclonal antibodies already available for microcystin detection, phage display technology represents a cheaper, more rapid alternative for the production of anti-microcystin antibodies than the methods currently in use.

Morphological control of gold nanorods via thermally driven bi-surfactant growth and application for detection of heavy metal ions.

PubMed

Huang, Hao; Li, Huiyi; Wang, Huaiyu; Li, Jia; Li, Penghui; Chen, Qidan; Chen, Yue; Chu, Paul K; Li, Bo; Yu, Xuefeng

2018-05-22

We report a modified synthesis route of colloidal gold nanorods (AuNRs) by combining the thermal re-shaping treatment and bi-surfactant modification using hexadecyltrimethylammonium bromide (CTAB) and sodium oleate (NaOL). Aspect ratios down to 1.3 ± 0.1 can be achieved in addition to good monodispersity, uniformity, and chemical stability of the materials. Furthermore, without needing post-treatment, metal ions directly interact with the AuNRs efficiently, allowing rapid and sensitive colorimetric detection of heavy metal ions such as Pb²⁺ and Cu²⁺ with a low concentration down to 2.5 μM. The detection performance in terms of selectivity, sensitivity and stability is systematically evaluated. The AuNRs with tunable aspect ratios as well as chemical stability have potential in surface-plasmon-based applications such as biochemical sensing, biochemical imaging, medical diagnostics, and cancer therapy. © 2018 IOP Publishing Ltd.

Preparation of Graphene-Modified Acupuncture Needle and Its Application in Detecting Neurotransmitters

PubMed Central

Tang, Lina; Du, Danxin; Yang, Fan; Liang, Zhong; Ning, Yong; Wang, Hua; Zhang, Guo-Jun

2015-01-01

We report a unique nanosensing platform by combining modern nanotechnology with traditional acupuncture needle to prepare graphene-modified acupuncture needle (G-AN), and using it for sensitive detection of neurotransmitters via electrochemistry. An electrochemical deposition method was employed to deposit Au nanoparticles (AuNPs) on the tip surface of the traditional acupuncture needle, while the other part of the needle was coated with insulation paste. Subsequently, the G-AN was obtained by cyclic voltammetry reduction of a graphene oxide solution on the surface of the AuNPs. To investigate the sensing property of the G-AN, pH dependence was measured by recording the open circuit potential in the various pH buffer solutions ranging from 2.0 to 10.0. What’s more, the G-AN was further used for detection of dopamine (DA) with a limit of detection of 0.24 μM. This novel G-AN exhibited a good sensitivity and selectivity, and could realize direct detection of DA in human serum. PMID:26112773

Colorimetric and Fluorescent Bimodal Ratiometric Probes for pH Sensing of Living Cells.

PubMed

Liu, Yuan-Yuan; Wu, Ming; Zhu, Li-Na; Feng, Xi-Zeng; Kong, De-Ming

2015-06-01

pH measurement is widely used in many fields. Ratiometric pH sensing is an important way to improve the detection accuracy. Herein, five water-soluble cationic porphyrin derivatives were synthesized and their optical property changes with pH value were investigated. Their pH-dependent assembly/disassembly behaviors caused significant changes in both absorption and fluorescence spectra, thus making them promising bimodal ratiometric probes for both colorimetric and fluorescent pH sensing. Different substituent identity and position confer these probes with different sensitive pH-sensing ranges, and the substituent position gives a larger effect. By selecting different porphyrins, different signal intensity ratios and different fluorescence excitation wavelengths, sensitive pH sensing can be achieved in the range of 2.1-8.0. Having demonstrated the excellent reversibility, good accuracy and low cytotoxicity of the probes, they were successfully applied in pH sensing inside living cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A sensitive aptasensor for colorimetric detection of adenosine triphosphate based on the protective effect of ATP-aptamer complexes on unmodified gold nanoparticles.

PubMed

Huo, Yuan; Qi, Liang; Lv, Xiao-Jun; Lai, Ting; Zhang, Jing; Zhang, Zhi-Qi

2016-04-15

Adenosine triphosphate (ATP) is the most direct source of energy in organisms. This study is the first to demonstrate that ATP-aptamer complexes provide greater protection for unmodified gold nanoparticles (AuNPs) against salt-induced aggregation than either aptamer or ATP alone. This protective effect was confirmed using transmission electron microscopy, dynamic light scattering, Zeta potential measurement, and fluorescence polarization techniques. Utilizing controlled particle aggregation/dispersion as a gauge, a sensitive and selective aptasensor for colorimetric detection of ATP was developed using ATP-binding aptamers as the identification element and unmodified AuNPs as the probe. This aptasensor exhibited a good linear relationship between the absorbance and the logarithm concentration of ATP within a 50-1000 nM range. ATP analogs such as guanosine triphosphate, uridine triphosphate and cytidine triphosphate resulted in little or no interference in the determination of ATP. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation, characterization and pharmacokinetics of fluorescence labeled propylene glycol alginate sodium sulfate

NASA Astrophysics Data System (ADS)

Li, Pengli; Li, Chunxia; Xue, Yiting; Zhang, Yang; Liu, Hongbing; Zhao, Xia; Yu, Guangli; Guan, Huashi

2014-08-01

A rapid and sensitive fluorescence labeling method was developed and validated for the microanalysis of a sulfated polysaccharide drug,namely propylene glycol alginate sodium sulfate (PSS), in rat plasma. Fluorescein isothiocyanate (FITC) was selected to label PSS, and 1, 6-diaminohexane was used to link PSS and FITC in order to prepare FITC-labeled PSS (F-PSS) through a reductive amination reaction. F-PSS was identified by UV-Vis, FT-IR and 1H-NMR spectrum. The cell stability and cytotoxicity of F-PSS were tested in Madin-Darby canine kidney (MDCK) cells. The results indicated that the labeling efficiency of F-PSS was 0.522% ± 0.0248% and the absolute bioavailability was 8.39%. F-PSS was stable in MDCK cells without obvious cytotoxicity. The method was sensitive and reliable; it showed a good linearity, precision, recovery and stability. The FITC labeling method can be applied to investigating the absorption and metabolism of PSS and other polysaccharides in biological samples.

Preparation of Graphene-Modified Acupuncture Needle and Its Application in Detecting Neurotransmitters

NASA Astrophysics Data System (ADS)

Tang, Lina; Du, Danxin; Yang, Fan; Liang, Zhong; Ning, Yong; Wang, Hua; Zhang, Guo-Jun

2015-06-01

We report a unique nanosensing platform by combining modern nanotechnology with traditional acupuncture needle to prepare graphene-modified acupuncture needle (G-AN), and using it for sensitive detection of neurotransmitters via electrochemistry. An electrochemical deposition method was employed to deposit Au nanoparticles (AuNPs) on the tip surface of the traditional acupuncture needle, while the other part of the needle was coated with insulation paste. Subsequently, the G-AN was obtained by cyclic voltammetry reduction of a graphene oxide solution on the surface of the AuNPs. To investigate the sensing property of the G-AN, pH dependence was measured by recording the open circuit potential in the various pH buffer solutions ranging from 2.0 to 10.0. What’s more, the G-AN was further used for detection of dopamine (DA) with a limit of detection of 0.24 μM. This novel G-AN exhibited a good sensitivity and selectivity, and could realize direct detection of DA in human serum.

Quantum dots assisted laser desorption/ionization mass spectrometric detection of carbohydrates: qualitative and quantitative analysis.

PubMed

Bibi, Aisha; Ju, Huangxian

2016-04-01

A quantum dots (QDs) assisted laser desorption/ionization mass spectrometric (QDA-LDI-MS) strategy was proposed for qualitative and quantitative analysis of a series of carbohydrates. The adsorption of carbohydrates on the modified surface of different QDs as the matrices depended mainly on the formation of hydrogen bonding, which led to higher MS intensity than those with conventional organic matrix. The effects of QDs concentration and sample preparation method were explored for improving the selective ionization process and the detection sensitivity. The proposed approach offered a new dimension to the application of QDs as matrices for MALDI-MS research of carbohydrates. It could be used for quantitative measurement of glucose concentration in human serum with good performance. The QDs served as a matrix showed the advantages of low background, higher sensitivity, convenient sample preparation and excellent stability under vacuum. The QDs assisted LDI-MS approach has promising application to the analysis of carbohydrates in complex biological samples. Copyright © 2016 John Wiley & Sons, Ltd.

Label-free nanoplasmonic sensing of tumor-associate autoantibodies for early diagnosis of colorectal cancer.

PubMed

Soler, Maria; Estevez, M-Carmen; Villar-Vazquez, Roi; Casal, J Ignacio; Lechuga, Laura M

2016-08-03

Colorectal cancer is treatable and curable when detected at early stages. However there is a lack of less invasive and more specific screening and diagnosis methods which would facilitate its prompt identification. Blood circulating autoantibodies which are immediately produced by the immune system at tumor appearance have become valuable biomarkers for preclinical diagnosis of cancer. In this work, we present the rapid and label-free detection of colorectal cancer autoantibodies directly in blood serum or plasma using a recently developed nanoplasmonic biosensor. Our nanoplasmonic device offers sensitive and real-time quantification of autoantibodies with excellent selectivity and reproducibility, achieving limits of detection around 1 nM (150-160 ng mL(-1)). A preliminary evaluation of clinical samples of colorectal cancer patients has shown good correlation with ELISA. These results demonstrate the reliability of the nanobiosensor strategy and pave the way towards the achievement of a sensitive diagnostic tool for early detection of colorectal cancer. Copyright © 2016 Elsevier B.V. All rights reserved.

Improved Bi Film Wrapped Single Walled Carbon Nanotubes for Ultrasensitive Electrochemical Detection of Trace Cr(VI).

PubMed

Ouyang, Ruizhuo; Zhang, Wangyao; Zhou, Shilin; Xue, Zi-Ling; Xu, Lina; Gu, Yingying; Miao, Yuqing

2013-12-15

We report here the successful fabrication of an improved Bi film wrapped single walled carbon nanotubes modified glassy carbon electrode (Bi/SWNTs/GCE) as a highly sensitive platform for ultratrace Cr(VI) detection through catalytic adsorptive cathodic stripping voltammetry (AdCSV). The introduction of negatively charged SWNTs extraordinarily decreased the size of Bi particles to nanoscale due to electrostatic interaction which made Bi(III) cations easily attracted onto the surface of SWNTs in good order, leading to higher quality of Bi film deposition. The obtained Bi/SWNTs composite was well characterized with electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), the static water contact angle and the voltammetric measurements. The results demonstrates the improvements in the quality of Bi film deposited on the surface of SWNTs such as faster speed of electron transfer, more uniform and smoother morphology, better hydrophilicity and higher stripping signal. Using diethylene triaminepentaacetic acid (DTPA) as complexing ligand, the fabricated electrode displays a well-defined and highly sensitive peak for the reduction of Cr(III)-DTPA complex at -1.06 V ( vs . Ag/AgCl) with a linear concentration range of 0-25 nM and a fairly low detection limit of 0.036 nM. No interference was found in the presence of coexisting ions, and good recoveries were achieved for the analysis of a river sample. In comparison to previous approaches using Bi film modified GCE, the newly designed electrode exhibits better reproducibility and repeatability towards aqueous detection of trace Cr(VI) and appears to be very promising as the basis of a highly sensitive and selective voltammetric procedure for Cr(VI) detection at trace level in real samples.

The reliability and validity of video analysis for the assessment of the clinical signs of concussion in Australian football.

PubMed

Makdissi, Michael; Davis, Gavin

2016-10-01

The objective of this study was to determine the reliability and validity of identifying clinical signs of concussion using video analysis in Australian football. Prospective cohort study. All impacts and collisions potentially resulting in a concussion were identified during 2012 and 2013 Australian Football League seasons. Consensus definitions were developed for clinical signs associated with concussion. For intra- and inter-rater reliability analysis, two experienced clinicians independently assessed 102 randomly selected videos on two occasions. Sensitivity, specificity, positive and negative predictive values were calculated based on the diagnosis provided by team medical staff. 212 incidents resulting in possible concussion were identified in 414 Australian Football League games. The intra-rater reliability of the video-based identification of signs associated with concussion was good to excellent. Inter-rater reliability was good to excellent for impact seizure, slow to get up, motor incoordination, ragdoll appearance (2 of 4 analyses), clutching at head and facial injury. Inter-rater reliability for loss of responsiveness and blank and vacant look was only fair and did not reach statistical significance. The feature with the highest sensitivity was slow to get up (87%), but this sign had a low specificity (19%). Other video signs had a high specificity but low sensitivity. Blank and vacant look (100%) and motor incoordination (81%) had the highest positive predictive value. Video analysis may be a useful adjunct to the side-line assessment of a possible concussion. Video analysis however should not replace the need for a thorough multimodal clinical assessment. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Improved Bi Film Wrapped Single Walled Carbon Nanotubes for Ultrasensitive Electrochemical Detection of Trace Cr(VI)

PubMed Central

Zhou, Shilin; Xue, Zi-Ling; Xu, Lina; Gu, Yingying; Miao, Yuqing

2014-01-01

We report here the successful fabrication of an improved Bi film wrapped single walled carbon nanotubes modified glassy carbon electrode (Bi/SWNTs/GCE) as a highly sensitive platform for ultratrace Cr(VI) detection through catalytic adsorptive cathodic stripping voltammetry (AdCSV). The introduction of negatively charged SWNTs extraordinarily decreased the size of Bi particles to nanoscale due to electrostatic interaction which made Bi(III) cations easily attracted onto the surface of SWNTs in good order, leading to higher quality of Bi film deposition. The obtained Bi/SWNTs composite was well characterized with electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), the static water contact angle and the voltammetric measurements. The results demonstrates the improvements in the quality of Bi film deposited on the surface of SWNTs such as faster speed of electron transfer, more uniform and smoother morphology, better hydrophilicity and higher stripping signal. Using diethylene triaminepentaacetic acid (DTPA) as complexing ligand, the fabricated electrode displays a well-defined and highly sensitive peak for the reduction of Cr(III)-DTPA complex at −1.06 V (vs. Ag/AgCl) with a linear concentration range of 0–25 nM and a fairly low detection limit of 0.036 nM. No interference was found in the presence of coexisting ions, and good recoveries were achieved for the analysis of a river sample. In comparison to previous approaches using Bi film modified GCE, the newly designed electrode exhibits better reproducibility and repeatability towards aqueous detection of trace Cr(VI) and appears to be very promising as the basis of a highly sensitive and selective voltammetric procedure for Cr(VI) detection at trace level in real samples. PMID:24771881

2D zirconium-based metal-organic framework nanosheets for highly sensitive detection of mucin 1: consistency between electrochemical and surface plasmon resonance methods

NASA Astrophysics Data System (ADS)

He, Linghao; Duan, Fenghe; Song, Yingpan; Guo, Chuanpan; Zhao, Hui; Tian, Jia-Yue; Zhang, Zhihong; Liu, Chun-Sen; Zhang, Xiaojing; Wang, Peiyuan; Du, Miao; Fang, Shao-Ming

2017-06-01

Two-dimensional (2D) zirconium-based metal-organic framework (denoted as 521-MOF) nanosheets with the thickness of 6.0-7.5 nm were prepared with the aid of polyvinyl pyrrolidone (PVP) under the mild conditions and low temperature (50 °C). Since 521-MOF nanosheets displayed good electrochemical activity, high surface area, and strong affinity interaction between the MOF and the oligonucleotides sequences, they can impel the immobilization of large amounts of aptamer strands when applied as a platform of biosensor. As a result, the developed aptasensor exhibited sensitive bio-recognition for the cancer determination marker protein, mucin 1 (MUC1). The combination of electrochemical techniques and surface plasmon resonance spectroscopy (SPR) was performed to probe the kinetic processes of the aptamer immobilization and the MUC1 detection. The consistency between different determination approaches was observed, in which the developed aptasensor based on 521-MOF nanosheets exhibits pretty high sensitivity for detecting MUC1 with a low detect limit of 0.12 and 0.65 pg·ml-1 deduced from electrochemical impedance spectroscopy and SPR, respectively, within the broad concentration range of MUC1 from 0.001 to 0.5 ng·ml-1. Simultaneously, a comparable affinity constant, K a, was derived from EIS and SPR, which also demonstrates that this new biosensing strategy has high selectivity, stability, reproducibility, and good applicability for the MUC1 detection in the human serum. The present finding indicates that the synthesized 521-MOF nanosheets can be employed in the fields of the biosensing or biomedical diagnosis and explored for different kinds of biosensors.

Dual nanoenzyme modified microelectrode based on carbon fiber coated with AuPd alloy nanoparticles decorated graphene quantum dots assembly for electrochemical detection in clinic cancer samples.

PubMed

Xu, Qi; Yuan, Hao; Dong, Xulin; Zhang, Yan; Asif, Muhammad; Dong, Zehua; He, Wenshan; Ren, Jinghua; Sun, Yimin; Xiao, Fei

2018-06-01

The development of high-efficient technologies for cancer biomarkers detection has attracted tremendous research effort for its great clinic significance. In this work, we designed a new type of flexible and robust nanohybrid microelectrode by modifying carbon fiber with dual nanoenzyme, i.e., AuPd alloy nanoparticles (AuPd-ANPs) decorated graphene quantum dots (GQDs) assembly, and explored its practical application in electrochemical sensing system for sensitive detection of cancer biomarker hydrogen peroxide (H 2 O 2 ) in human breast cancer cells and tissue. For the preparation of dual nanoenzyme modified microelectrode, ionic liquid was used as the electrolyte for the effective electrodeposition of GQDs on carbon fiber substrate to form a close-packed assembly under a very negative potential, then the highly dense AuPd-ANPs were uniformly decorated on GQDs assembly by electrodeposition. In virtue of the structural merits and synergistic contribution of dual nanoenzyme in enhancing the electrocatalytic activity to H 2 O 2 , the resultant nanohybrid microelectrode exhibited good sensing performances for electrochemical detection of H 2 O 2 , including a high sensitivity of 371 μA cm -2 mM -1 , a wide linear range from 1.0 μM to 18.44 mM, a low detection limit of 500 nM (a signal-to-noise ratio of 3:1), as well as good selectivity and biocompatibility, which could be used for real-time tracking H 2 O 2 released from different types of human breast cells and in situ sensitive detection of H 2 O 2 in clinical breast cancer tissue. Copyright © 2018 Elsevier B.V. All rights reserved.

Short-Term Genetic Selection for Adolescent Locomotor Sensitivity to Delta9-Tetrahydrocannabinol (THC).

PubMed

Kasten, Chelsea R; Zhang, Yanping; Mackie, Ken; Boehm, Stephen L

2018-05-01

Cannabis use is linked to positive and negative outcomes. Identifying genetic targets of susceptibility to the negative effects of cannabinoid use is of growing importance. The current study sought to complete short-term selective breeding for adolescent sensitivity and resistance to the locomotor effects of a single 10 mg/kg THC dose in the open field. Selection for THC-locomotor sensitivity was moderately heritable, with the greatest estimates of heritability seen in females from the F2 to S3 generations. Selection for locomotor sensitivity also resulted in increased anxiety-like activity in the open field. These results are the first to indicate that adolescent THC-locomotor sensitivity can be influenced via selective breeding. Development of lines with a genetic predisposition for THC-sensitivity or resistance to locomotor effects allow for investigation of risk factors, differences in consequences of THC use, identification of correlated behavioral responses, and detection of genetic targets that may contribute to heightened cannabinoid sensitivity.

Sensitivity of Earth Wheat Markets to Space Weather: Comparative Analysis based on data from Medieval European Markets

NASA Astrophysics Data System (ADS)

Pustil'Nik, Lev

We consider a problem of the possible influence of unfavorable states of the space weather on agriculture markets through the chain of connections: "space weather"-"earth weather"- "agriculture crops"-"price reaction". We show that new manifestations of "space weather"- "earth weather" relations discovered in the recent time allow revising a wide range of the expected solar-terrestrial connections. In the previous works we proposed possible mechanisms of wheat market reaction on the specific unfavorable states of space weather in the form of price bursts and price asymmetry. We point out that implementation of considered "price reaction scenarios" is possible only for the case of simultaneous realization of several necessary conditions: high sensitivity of local earth weather in the selected region to space weather; the state of "high risk agriculture" in the selected agriculture zone; high sensitivity of agricultural market to a possible deficit of yield. Results of our previous works (I, II), including application of this approach to the Medieval England wheat market (1250-1700) and to the modern USA durum market (1910-1992), showed that connection between wheat price bursts and space weather state in these cases was absolutely real. The aim of the present work is to answer the question why wheat markets in one selected region may be sensitive to a space weather factor, while in other regions wheat markets demonstrate absolutely indifferent reaction on the space weather. For this aim, we consider dependence of sensitivity of wheat markets to space weather as a function of their location in different climatic zones of Europe. We analyze a database of 95 European wheat markets from 14 countries for the 600-year period (1260-1912). We show that the observed sensitivity of wheat markets to space weather effects is controlled, first of all, by a type of predominant climate in different zones of agricultural production. Wheat markets in the Northern and, partly, in Central Europe (England, Holland, Belgium) show high sensitivity to space weather in minimum states of solar activity, when excess of the high energy cosmic ray stimulate additional cloudiness and precipitation. In the same time, wheat markets in the Southern Europe (Spain, Italy) show high sensitivity to space weather state in the opposite (maximum) phase of solar activity when a deficit of cosmic ray entering into the earth atmosphere leads to decrease of cloudiness and to increase of probability of drought weather periods. We demonstrate that the large part of markets in the Central Europe zone show absence of any effects of sensitivity to space weather state and show that this North-South asymmetry is in good accordance with the suggested model of expected wheat market reaction. We discuss possible increasing of sensitivity of wheat markets to space weather effects under conditions of fast and drastic change of modern climate with a shift of numerous agriculture regions to the state of "high risk agriculture zone".

A wide range and highly sensitive optical fiber pH sensor using polyacrylamide hydrogel

NASA Astrophysics Data System (ADS)

Pathak, Akhilesh Kumar; Singh, Vinod Kumar

2017-12-01

In the present study we report the fabrication and characterization of no-core fiber sensor (NCFS) using smart hydrogel coating for pH measurement. The no-core fiber (NCF) is stubbed between two single-mode fibers with SMA connector before immobilizing of smart hydrogel. The wavelength interrogation technique is used to calculate the sensitivity of the proposed sensor. The result shows a high sensitivity of 1.94 nm/pH for a wide range of pH values varied from 3 to 10 with a good linear response. In addition to high sensitivity, the fabricated sensor provides a fast response time with a good stability, repeatability and reproducibility.

Access to Gender-Sensitive Higher Education in Eastern and Central Europe: Reflections on the CEPES Project "Good Practice in Promoting Gender Equality in Higher Education"

ERIC Educational Resources Information Center

Grunberg, Laura

2005-01-01

Summarizing the incomplete results of the United Nations Educational and Scientific Organization (UNESCO) program "Good Practice in Promoting Gender Equality in Higher Education," the author asks that any assessment of the progress made in the area of gender-sensitive education take regional specificities into account. The regional…

Development of an extended-range fiber optic pH sensor using evanescent wave absorption of sol-gel-entrapped pH indicators

NASA Astrophysics Data System (ADS)

Butler, Thomas M.; MacCraith, Brian D.; McDonagh, Colette M.

1995-09-01

The sol-gel process has been used to entrap pH indicators in porous glass coatings for sensor applications. This sensor is based on evanescent wave absorption using an unclad optical fiber dipcoated with the pH sensitive coating. The entrapped pH indicators show a broadening of the pH range with respect to the behavior in solution giving accurate measurement over three pH units when one indicator is used (bromophenol blue) and over six pH units (pH 3-9) when two indicators are used (bromophenol blue and bromocresol purple). The response of the pH sensor was monitored by measuring absorption at 590 nm referenced against a nonabsorbing region of the spectrum. This enabled the use of LED sources together with low cost photodiodes. The sensor displayed short response time and good repeatability. The thickness and stability of the pH sensitive coatings can be influenced by modifying the composition of the starting sol mixture. The evanescent absorption, and hence the sensitivity of the sensor, can be increased by selectively launching higher order modes in the fiber. These issues together with a full sensor characterization will be reported.

Detection of LipL32-specific IgM by ELISA in sera of patients with a clinical diagnosis of leptospirosis

PubMed Central

Vedhagiri, Kumaresan; Velineni, Sridhar; Timoney, John F; Shanmughapriya, Santhanam; Vijayachari, Paluru; Narayanan, Ramasamy; Natarajaseenivasan, Kalimuthusamy

2013-01-01

Successful treatment of leptospirosis is heavily dependent on early diagnosis and prompt initiation of antibiotic therapy. An ELISA test to detect specific IgM antibodies against LipL32 for early diagnosis of leptospirosis is described and evaluated here. One thousand one hundred and eighty sera from clinically suspected leptospirosis cases were enrolled together with 109 healthy volunteers selected from an endemic area between October 2007 and January 2010. Patients were categorized based on their clinical signs and symptoms. Sera were screened for leptospiral antibodies by the microscopic agglutination test (MAT) using a panel of locally circulating serovars followed by enzyme-linked immunosorbent assay (ELISA) based on recombinant LipL32 from Leptospira interrogans serovar Autumnalis strain N2. The sensitivity and specificity of the ELISA test were determined to establish its diagnostic efficiency. The cut-off value was determined to be 0.205. Overall sensitivity and specificity compared to the MAT were found to be 96.4 and 90.4%, respectively. The LipL32-specific IgM ELISA had good sensitivity and acceptable specificity and may be a candidate for the early serodiagnosis of human leptospirosis. PMID:23683367

The Use of Radiation Response (RR) in Selecting the Method of Treatment of Carcinoma Cervicis Uteri

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

Chesterman, John N.

1963-03-01

Attempts were made to determine the choice treatment of cervical squamous carcinoma (surgery, radiation, or surgery with radiation) in Stages I and II. A study of 50 patients showed good results from surgery in patients with poor radiation response (RR) and that the RR, estimated by a precise and uniform technique, will identify those patients who will not respond well to complete radiation therapy. Moreover, it will do this after a first radium application of moderate dosage, at a time when it is still possible to interrupt this therapy. A radiation dose of at least 1000 r at the cervixmore » will be followed by the maximum RR, in a good response, between the 8th and 14th (especially 10th to 12th) days. A poor RR will reach its maximum earlier than a good one, on about the 10th day after radium implantation. When deciding the definition of good RR, it was found that the radiation changes present in a count of 100 cells were seen in more than 70 cells. There is evidence that age, menopause, and hormonal status influence the radiation reaction. If poor RR is more frequently found with high estrogenic activity, young patients treated by radiation should be expected to have a worse survival rate than old. The survival rate is about 1/3) in the young patient as against 1/2 in the postmenopausal. A good sensitization response (SR) was, in most cases, followed by good RR after radiation. Of 39 patients with good SR, 34 had good RR after one application of radium. However, this correlation was absent when the SR was poor. Of 41 patients with poor SR, 18 remained poor after radiation and 23 developed good RR. Finally, this SR should not be taken alone as a guide to treatment, but all patients should be given the first radium application and the RR assessed.« less

Selective Detection of Neurotransmitters by Fluorescence and Chemiluminescence Imaging

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

Ziqiang Wang; Edward S. Yeung

In recent years, luminescence imaging has been widely employed in neurochemical analysis. It has a number of advantages for the study of neuronal and other biological cells: (1) a particular molecular species or cellular constituent can be selectively visualized in the presence of a large excess of other species in a heterogeneous environment; (2) low concentration detection limits can be achieved because of the inherent sensitivity associated with fluorescence and chemiluminescence; (3) low excitation intensities can be used so that long-term observation can be realized while the viability of the specimen is preserved; and (4) excellent spatial resolution can bemore » obtained with the light microscope so subcellular compartments can be identified. With good sensitivity, temporal and spatial resolution, the flux of ions and molecules and the distribution and dynamics of intracellular species can be measured in real time with specific luminescence probes, substrates, or with native fluorescence. A noninvasive detection scheme based on glutamate dehydrogenase (GDH) enzymatic assay combined with microscopy was developed to measure the glutamate release in cultured cells from the central nervous system (CNS). The enzyme reaction is very specific and sensitive. The detection limit with CCD imaging is down to {micro}M levels of glutamate with reasonable response time. They also found that chemiluminescence associated with the ATP-dependent reaction between luciferase and luciferin can be used to image ATP at levels down to 10 nM in the millisecond time scale. Similar imaging experiments should be feasible in a broad spectrum of biological systems.« less

Statistical method evaluation for differentially methylated CpGs in base resolution next-generation DNA sequencing data.

PubMed

Zhang, Yun; Baheti, Saurabh; Sun, Zhifu

2018-05-01

High-throughput bisulfite methylation sequencing such as reduced representation bisulfite sequencing (RRBS), Agilent SureSelect Human Methyl-Seq (Methyl-seq) or whole-genome bisulfite sequencing is commonly used for base resolution methylome research. These data are represented either by the ratio of methylated cytosine versus total coverage at a CpG site or numbers of methylated and unmethylated cytosines. Multiple statistical methods can be used to detect differentially methylated CpGs (DMCs) between conditions, and these methods are often the base for the next step of differentially methylated region identification. The ratio data have a flexibility of fitting to many linear models, but the raw count data take consideration of coverage information. There is an array of options in each datatype for DMC detection; however, it is not clear which is an optimal statistical method. In this study, we systematically evaluated four statistic methods on methylation ratio data and four methods on count-based data and compared their performances with regard to type I error control, sensitivity and specificity of DMC detection and computational resource demands using real RRBS data along with simulation. Our results show that the ratio-based tests are generally more conservative (less sensitive) than the count-based tests. However, some count-based methods have high false-positive rates and should be avoided. The beta-binomial model gives a good balance between sensitivity and specificity and is preferred method. Selection of methods in different settings, signal versus noise and sample size estimation are also discussed.

An enhanced cerium(IV)-rhodamine 6G chemiluminescence system using guest-host interactions in a lab-on-a-chip platform for estimating the total phenolic content in food samples.

PubMed

Al Haddabi, Buthaina; Al Lawati, Haider A J; Suliman, FakhrEldin O

2016-04-01

Two chemiluminescence-microfluidic (CL-MF) systems, e.g., Ce(IV)-rhodamine B (RB) and Ce(IV)-rhodamine 6G (R6G), for the determination of the total phenolic content in teas and some sweeteners were evaluated. The results indicated that the Ce(IV)-R6G system was more sensitive in comparison to the Ce(IV)-RB CL system. Therefore, a simple (CL-MF) method based on the CL of Ce(IV)-R6G was developed, and the sensitivity, selectivity and stability of this system were evaluated. Selected phenolic compounds (PCs), such as quercetin (QRC), catechin (CAT), rutin (RUT), gallic acid (GA), caffeic acid (CA) and syringic acid (SA), produced analytically useful chemiluminescence signals with low detection limits ranging from 0.35 nmol L(-1) for QRC to 11.31 nmol L(-1) for SA. The mixing sequence and the chip design were crucial, as the sensitivity and reproducibility could be substantially affected by these two factors. In addition, the anionic surfactant (i.e., sodium dodecyl sulfate (SDS)) can significantly enhance the CL signal intensity by as much as 300% for the QRC solution. Spectroscopic studies indicated that the enhancement was due to a strong guest-host interaction between the cationic R6G molecules and the anionic amphiphilic environment. Other parameters that could affect the CL intensities of the PCs were carefully optimized. Finally, the method was successfully applied to tea and sweetener samples. Six different tea samples exhibited total phenolic/antioxidant levels from 7.32 to 13.5 g per 100g of sample with respect to GA. Four different sweetener samples were also analyzed and exhibited total phenolic/antioxidant levels from 500.9 to 3422.9 mg kg(-1) with respect to GA. The method was selective, rapid and sensitive when used to estimate the total phenolic/antioxidant level, and the results were in good agreement with those reported for honey and tea samples. Copyright © 2015 Elsevier B.V. All rights reserved.

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

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

Guo, Xuejiang; Tang, Keqi

Searching for disease specific biomarkers has become a major undertaking in the biomedical research field as the effective diagnosis, prognosis and treatment of many complex human diseases are largely determined by the availability and the quality of the biomarkers. A successful biomarker as an indicator to a specific biological or pathological process is usually selected from a large group of candidates by a strict verification and validation process. To be clinically useful, the validated biomarkers must be detectable and quantifiable by the selected testing techniques in their related tissues or body fluids. Due to its easy accessibility, protein biomarkers wouldmore » ideally be identified in blood plasma or serum. However, most disease related protein biomarkers in blood exist at very low concentrations (<1ng/mL) and are “masked” by many none significant species at orders of magnitude higher concentrations. The extreme requirements of measurement sensitivity, dynamic range and specificity make the method development extremely challenging. The current clinical protein biomarker measurement primarily relies on antibody based immunoassays, such as ELISA. Although the technique is sensitive and highly specific, the development of high quality protein antibody is both expensive and time consuming. The limited capability of assay multiplexing also makes the measurement an extremely low throughput one rendering it impractical when hundreds to thousands potential biomarkers need to be quantitatively measured across multiple samples. Mass spectrometry (MS)-based assays have recently shown to be a viable alternative for high throughput and quantitative candidate protein biomarker verification. Among them, the triple quadrupole MS based assay is the most promising one. When it is coupled with liquid chromatography (LC) separation and electrospray ionization (ESI) source, a triple quadrupole mass spectrometer operating in a special selected reaction monitoring (SRM) mode, also known as multiple reaction monitoring (MRM), is capable of quantitatively measuring hundreds of candidate protein biomarkers from a relevant clinical sample in a single analysis. The specificity, reproducibility and sensitivity could be as good as ELISA. Furthermore, SRM MS can also quantify protein isoforms and post-translational modifications, for which traditional antibody-based immunoassays often don’t exist.« less

A novel pyrimidine derivative as a fluorescent chemosensor for highly selective detection of Aluminum (III) in aqueous media

NASA Astrophysics Data System (ADS)

Suryawanshi, Vishwas D.; Gore, Anil H.; Dongare, Pravin R.; Anbhule, Prashant V.; Patil, Shivajirao R.; Kolekar, Govind B.

2013-10-01

An efficient fluorescent chemosensor Al3+ receptor based on pyrimidine derivative,2-amino-6-hydroxy-4-(4-N,N-dimethylaminophenyl)-pyrimidine-5-carbonitrile (DMAB), has been synthesized by three-component condensation of aromatic aldehyde, ethyl cyanoacetate and guanidine hydrochloride in ethanol under alkaline medium. High selectivity and sensitivity of DMAB towards Aluminum ion (Al3+) in water: ethanol and acetate buffer at pH 4.0 makes it suitable to detect Al3+ with steady-state UV-vis and fluorescence spectroscopy. Method shows good selectivity towards Al3+ over other coexisting metal ions tested, viz. Fe2+, Ni2+, Cu2+, Co2+, Pb2+, Sb3+, Na+, Ca2+, Mg2+, Zn2+, Hg2+, Ba2+, Cd2+ and K+. A good linearity between the Stern-Volmer plots of F0/F versus concentration of Al3+ was observed over the range from 10 to 60 μg mL-1 with correlation coefficient of 0.991. The accuracy and reliability of the method were further confirmed by recovery studies via standard addition method with percent recoveries in the range of 101.03-103.44% and lowest detection limit (LOD = 7.35 μg mL-1) for Al3+ was established. This method may offer a new cost-effective, rapid, and simple key to the inspection of Al3+ ions in water samples in the presence of a complex matrix and can be capable of evaluating the exceeding standard of Al3+ in environmental water samples. The probable mechanism for fluorescence quenching was also discussed.

Sol-gel based optical sensor for determination of Fe (II): a novel probe for iron speciation.

PubMed

Samadi-Maybodi, Abdolraouf; Rezaei, Vida; Rastegarzadeh, Saadat

2015-02-05

A highly selective optical sensor for Fe (II) ions was developed based on entrapment of a sensitive reagent, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), in a silica sol-gel thin film coated on a glass substrate. The thin films fabricated based on tetraethoxysilane (TEOS) as precursor, sol-gel pH∼3, water:alkoxyde ratio of 4:1 and TPTZ concentration of 0.112 mol L(-1). The influence of sol-gel parameters on sensing behavior of the fabricated sensor was also investigated. The fabricated sensor can be used for determination of Fe (II) ion with an outstanding high selectivity over a dynamic range of 5-115 ng mL(-1) and a detection limit of 1.68 ng mL(-1). It also showed reproducible results with relative standard deviation of 3.5% and 1.27% for 10 and 90 ng mL(-1) of Fe (II), respectively, along with a fast response time of ∼120 s. Total iron also was determined after reduction of Fe (III) to Fe (II) using ascorbic acid as reducing agent. Then, the concentration of Fe (III) was calculated by subtracting the concentration of Fe (II) from the total iron concentration. Interference studies showed a good selectivity for Fe (II) with trapping TPTZ into sol-gel matrix and appropriately adjusting the structure of doped sol-gel. The sensor was compared with other sensors and was applied to determine iron in different water samples with good results. Copyright © 2014 Elsevier B.V. All rights reserved.

A novel "signal-on/off" sensing platform for selective detection of thrombin based on target-induced ratiometric electrochemical biosensing and bio-bar-coded nanoprobe amplification strategy.

PubMed

Wang, Lanlan; Ma, Rongna; Jiang, Liushan; Jia, Liping; Jia, Wenli; Wang, Huaisheng

2017-06-15

A novel dual-signal ratiometric electrochemical aptasensor for highly sensitive and selective detection of thrombin has been designed on the basis of signal-on and signal-off strategy. Ferrocene labeled hairpin probe (Fc-HP), thrombin aptamer and methyl blue labeled bio-bar-coded AuNPs (MB-P3-AuNPs) were rationally introduced for the construction of the assay platform, which combined the advantages of the recognition of aptamer, the amplification of bio-bar-coded nanoprobe, and the ratiometric signaling readout. In the presence of thrombin, the interaction between thrombin and the aptamer leads to the departure of MB-P3-AuNPs from the sensing interface, and the conformation of the single stranded Fc-HP to a hairpin structure to take the Fc confined near the electrode surface. Such conformational changes resulted in the oxidation current of Fc increased and that of MB decreased. Therefore, the recognition event of the target can be dual-signal ratiometric electrochemical readout in both the "signal-off" of MB and the "signal-on" of Fc. The proposed strategy showed a wide linear detection range from 0.003 to 30nM with a detection limit of 1.1 pM. Moreover, it exhibits good performance of excellent selectivity, good stability, and acceptable fabrication reproducibility. By changing the recognition probe, this protocol could be easily expanded into the detection of other targets, showing promising potential applications in disease diagnostics and bioanalysis. Copyright © 2016. Published by Elsevier B.V.

Miniaturized matrix solid-phase dispersion followed by liquid chromatography-tandem mass spectrometry for the quantification of synthetic dyes in cosmetics and foodstuffs used or consumed by children.

PubMed

Guerra, Eugenia; Llompart, Maria; Garcia-Jares, Carmen

2017-12-22

Miniaturized matrix solid-phase dispersion (MSPD) followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) has been proposed for the simultaneous analysis of different classes of synthetic dyes in confectionery and cosmetics intended for or mostly consumed by children. Selected compounds include most of the permitted dyes as food additives as well as some of the most frequently used to color cosmetic products in accordance with the respective European directives. MSPD procedure was optimized by means of experimental design, allowing an effective, rapid and simple extraction of dyes with low sample and reagents consumption (0.1g of sample and 2mL of elution solvent). LC-MS/MS was optimized for good resolution, selectivity and sensitivity using a low ionic strength mobile phase (3mM NH 4 Ac-methanol). Method performance was demonstrated in real samples showing good linearity (R≥0.9928) and intra- and inter-day precision (%RSD≤15%). Method LODs were ≤0.952μgg -1 and ≤0.476μgg -1 for confectionery and cosmetic samples, respectively. Recoveries of compounds from nine different matrices were quantitative. The validated method was successfully applied to 24 commercial samples (14 cosmetics and 10 foods) in which 9 of the selected dyes were found at concentrations up to 989μgg -1 , exceeding in some cases the regulated maximum permitted limits. A non-permitted dye, Acid Orange 7, was found in one candy. Copyright © 2017 Elsevier B.V. All rights reserved.

Planck, Herschel & Spitzer unveil overdense z>2 regions

NASA Astrophysics Data System (ADS)

Dole, Herve; Chary, Ranga-Ram; Chary, Ranga; Frye, Brenda; Martinache, Clement; Guery, David; Le Floc'h, Emeric; Altieri, Bruno; Flores-Cacho, Ines; Giard, Martin; Hurier, Guillaume; Lagache, Guilaine; Montier, Ludovic; Nesvadba, Nicole; Omont, Alain; Pointecouteau, Etienne; Pierini, Daniele; Puget, Jean-Loup; Scott, Douglas; Soucail, Genevieve

2014-12-01

At which cosmic epoch did massive galaxy clusters assemble their baryons? How does star formation occur in the most massive, most rapidly collapsing dark-matter-dense environments in the early Universe? To answer these questions, we take the completely novel approach to select the most extreme z>~2 star-forming overdensities seen over the entire sky. This selection nicely complements the other existing selections for high redshift clusters (i.e., by stellar mass, or by total mass like Sunyaev-Zeldovish (SZ) or X-ray selection). We make use of the Planck all-sky submillimetre survey to systematically identify the rarest, most luminous high-redshift sub-mm sources on the sky, either strongly gravitationally lensed galaxies, or the joint FIR/sub-mm emission from multiple intense starbursts. We observed 228 Planck sources with Herschel/SPIRE and discovered that most of them are overdensities of red galaxies with extremely high star formation rates (typically 7.e3 Msun/yr for a structure). Only Spitzer data can allow a better understanding of these promising Planck+Herschel selected sources, as is shown on a first set of IRAC data on 40 targets in GO9: (i) the good angular resolution and sensitivity of IRAC allows a proper determination of the clustered nature of each Herschel/SPIRE source; (ii) IRAC photometry (often associated with J, K) allows a good estimate of the colors and approximate photometric redshift. Note spectroscopic redshifts are available for two cluster candidates, at z=1.7 and z=2.3, confirming their high redshift nature. The successful GO9 observation of 40 fields showed that about half to be >7sigma overdensities of red IRAC sources. These observations were targeting the whole range of Herschel overdensities and significances. We need to go deeper into the Spitzer sample and acquire complete coverage of the most extreme Herschel overdensities (54 new fields). Such a unique sample has legacy value, and this is the last opportunity prior to JWST, WFIRST and Euclid.

Why do adults entitled to free or highly subsidized dental services select fully out-of-pocket-paid care?

PubMed

Bayat, Fariborz; Vehkalahti, Miira M; Murtomaa, Heikki; Tala, Heikki

2010-02-01

To investigate patients' reasons for selecting a dental clinic given their choice of free or highly-subsidized dental services. The study was based on cross-sectional data obtained through phone interviews with adults in Tehran, Iran. The present study included those entitled to free or highly-subsidized dental services (n = 726). The data covered the patients' awareness of subsidized dental services and type of dental clinic for their most recent visit and their reasons for selecting that clinic. Awareness of subsidized dental services was dichotomized as being either aware or unaware of such subsidy. The type of clinic was dichotomized as providing either free or highly-subsidized (FHS) or fully out-of-pocket paid (FOP) services. Free format answers about the subjects' reasons for selecting a particular clinic were later sub-grouped as: convenient access, good technical aspects, good interpersonal aspects, low or reasonable fees, recommendation by a friend, and no reason. Socio-demographic status was based on background. Data analysis included the chi-square test and logistic regression model. Of the subjects (n = 726), 60% were women and 58% were under 35 years of age. The subjects' mean age was 33.5 years with no difference by gender (P = 0.24) and the majority had public insurance (91%). Of all the subjects, 60% selected FOP. Good interpersonal aspects were the strongest reason for selecting FOP (OR = 4.6), follow by good technical aspects (OR = 2.3). Those subjects who were unaware of their benefit had 4.6 times the odds of selecting FOP. Despite the opportunity to use highly-subsidized dental services, good interpersonal and good technical aspects lead patients to select private dentists and to pay fully out of pocket.

Aerospace Non Chrome Corrosion Inhibiting Primer Systems

DTIC Science & Technology

2009-09-01

Meet all HSE specifications, TSCA, REACh, Akzo • Strippable • No weight increase over current system • Meet specification requirements for corrosion, not...Positive and negative controls • Primer only and topcoated samples Aerospace Coatings | Title 9 OEM CF Optimization/ Down Selects •Usual issues...found to be true • Good NSS ≠ Good filiform ≠ Good cure ≠ Good application properties • Down select process is to minimize ≠ and move to a balance of

Molecular switch-modulated fluorescent copper nanoclusters for selective and sensitive detection of histidine and cysteine.

PubMed

Gu, Zefeng; Cao, Zhijuan

2018-06-07

A novel assay for histidine and cysteine has been constructed based on modulation of fluorescent copper nanoclusters (CuNCs) by molecular switches. In our previous work, a dumbbell DNA template with a poly-T (thymine) loop has been developed as an excellent template for the formation of strongly fluorescent CuNCs. Herein, for the first time, we established this biosensor for sensing two amino acids by using dumbbell DNA-templated CuNCs as the single probe. Among 20 natural amino acids, only histidine and cysteine can selectively quench fluorescence emission of CuNCs, because of the specific interaction of these compounds with copper ions. Furthermore, by using nickel ions (Ni 2+ ) and N-ethylmaleimide as the masking agents for histidine and cysteine respectively, an integrated logic gate system was designed by coupling with the fluorescent CuNCs and demonstrated selective and sensitive detection of cysteine and histidine. Under optimal conditions, cysteine can be detected in the concentration ranges of 0.01-10.0 μM with the detection limit (DL) of as low as 98 pM, while histidine can be detected in the ranges of 0.05-40.0 μM with DL of 1.6 nM. In addition, histidine and cysteine can be observed with the naked eye under a hand-held UV lamp (DL, 50 nM), which can be easily adapted to automated high-throughput screening. Finally, the strategy has been successfully utilized for biological fluids. The proposed system can be conducted in homogeneous solution, eliminating the need for organic cosolvents, separation processes of nanomaterials, or any chemical modifications. Overall, the assay provides an alternative method for simultaneous detection of cysteine and histidine by taking the advantages of high speed, no label and enzyme requirement, and good sensitivity and specificity, and will satisfy the great demand for determination of amino acids in fields such as food processing, biochemistry, pharmaceuticals, and clinical analysis. Graphical abstract.

Robust artificial neural network for reliability and sensitivity analyses of complex non-linear systems.

PubMed

Oparaji, Uchenna; Sheu, Rong-Jiun; Bankhead, Mark; Austin, Jonathan; Patelli, Edoardo

2017-12-01

Artificial Neural Networks (ANNs) are commonly used in place of expensive models to reduce the computational burden required for uncertainty quantification, reliability and sensitivity analyses. ANN with selected architecture is trained with the back-propagation algorithm from few data representatives of the input/output relationship of the underlying model of interest. However, different performing ANNs might be obtained with the same training data as a result of the random initialization of the weight parameters in each of the network, leading to an uncertainty in selecting the best performing ANN. On the other hand, using cross-validation to select the best performing ANN based on the ANN with the highest R 2 value can lead to biassing in the prediction. This is as a result of the fact that the use of R 2 cannot determine if the prediction made by ANN is biased. Additionally, R 2 does not indicate if a model is adequate, as it is possible to have a low R 2 for a good model and a high R 2 for a bad model. Hence, in this paper, we propose an approach to improve the robustness of a prediction made by ANN. The approach is based on a systematic combination of identical trained ANNs, by coupling the Bayesian framework and model averaging. Additionally, the uncertainties of the robust prediction derived from the approach are quantified in terms of confidence intervals. To demonstrate the applicability of the proposed approach, two synthetic numerical examples are presented. Finally, the proposed approach is used to perform a reliability and sensitivity analyses on a process simulation model of a UK nuclear effluent treatment plant developed by National Nuclear Laboratory (NNL) and treated in this study as a black-box employing a set of training data as a test case. This model has been extensively validated against plant and experimental data and used to support the UK effluent discharge strategy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Potentiometric Zinc Ion Sensor Based on Honeycomb-Like NiO Nanostructures

PubMed Central

Abbasi, Mazhar Ali; Ibupoto, Zafar Hussain; Hussain, Mushtaque; Khan, Yaqoob; Khan, Azam; Nur, Omer; Willander, Magnus

2012-01-01

In this study honeycomb-like NiO nanostructures were grown on nickel foam by a simple hydrothermal growth method. The NiO nanostructures were characterized by field emission electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The characterized NiO nanostructures were uniform, dense and polycrystalline in the crystal phase. In addition to this, the NiO nanostructures were used in the development of a zinc ion sensor electrode by functionalization with the highly selective zinc ion ionophore 12-crown-4. The developed zinc ion sensor electrode has shown a good linear potentiometric response for a wide range of zinc ion concentrations, ranging from 0.001 mM to 100 mM, with sensitivity of 36 mV/decade. The detection limit of the present zinc ion sensor was found to be 0.0005 mM and it also displays a fast response time of less than 10 s. The proposed zinc ion sensor electrode has also shown good reproducibility, repeatability, storage stability and selectivity. The zinc ion sensor based on the functionalized NiO nanostructures was also used as indicator electrode in potentiometric titrations and it has demonstrated an acceptable stoichiometric relationship for the determination of zinc ion in unknown samples. The NiO nanostructures-based zinc ion sensor has potential for analysing zinc ion in various industrial, clinical and other real samples. PMID:23202217

Selective breeding for magnitude of methamphetamine-induced sensitization alters methamphetamine consumption

PubMed Central

Scibelli, Angela C.; McKinnon, Carrie S.; Reed, Cheryl; Burkhart-Kasch, Sue; Li, Na; Baba, Harue; Wheeler, Jeanna M.

2012-01-01

Rationale Genetically determined differences in susceptibility to drug-induced sensitization could be related to risk for drug consumption. Objectives Studies were performed to determine whether selective breeding could be used to create lines of mice with different magnitudes of locomotor sensitization to methamphetamine (MA). MA sensitization (MASENS) lines were also examined for genetically correlated responses to MA. Methods Beginning with the F2 cross of C57BL/6J and DBA/2J strains, mice were tested for locomotor sensitization to repeated injections of 1 mg/kg MA and bred based on magnitude of sensitization. Five selected offspring generations were tested. All generations were also tested for MA consumption, and some were tested for dose-dependent locomotor-stimulant responses to MA, consumption of saccharin, quinine, and potassium chloride as a measure of taste sensitivity, and MA clearance after acute and repeated MA. Results Selective breeding resulted in creation of two lines [MA high sensitization (MAHSENS) and MA low sensitization (MALSENS)] that differed in magnitude of MA-induced sensitization. Initially, greater MA consumption in MAHSENS mice reversed over the course of selection so that MALSENS mice consumed more MA. MAHSENS mice exhibited greater sensitivity to the acute stimulant effects of MA, but there were no significant differences between the lines in MA clearance from blood. Conclusions Genetic factors influence magnitude of MA-induced locomotor sensitization and some of the genes involved in magnitude of this response also influence MA sensitivity and consumption. Genetic factors leading to greater MA-induced sensitization may serve a protective role against high levels of MA consumption. PMID:21088960

Comparative study of ZnO nanorods and thin films for chemical and biosensing applications and the development of ZnO nanorods based potentiometric strontium ion sensor

NASA Astrophysics Data System (ADS)

Khun, K.; Ibupoto, Z. H.; Chey, C. O.; Lu, Jun.; Nur, O.; Willander, M.

2013-03-01

In this study, the comparative study of ZnO nanorods and ZnO thin films were performed regarding the chemical and biosensing properties and also ZnO nanorods based strontium ion sensor is proposed. ZnO nanorods were grown on gold coated glass substrates by the hydrothermal growth method and the ZnO thin films were deposited by electro deposition technique. ZnO nanorods and thin films were characterised by field emission electron microscopy [FESEM] and X-ray diffraction [XRD] techniques and this study has shown that the grown nanostructures are highly dense, uniform and exhibited good crystal quality. Moreover, transmission electron microscopy [TEM] was used to investigate the quality of ZnO thin film and we observed that ZnO thin film was comprised of nano clusters. ZnO nanorods and thin films were functionalised with selective strontium ionophore salicylaldehyde thiosemicarbazone [ST] membrane, galactose oxidase, and lactate oxidase for the detection of strontium ion, galactose and L-lactic acid, respectively. The electrochemical response of both ZnO nanorods and thin films sensor devices was measured by using the potentiometric method. The strontium ion sensor has exhibited good characteristics with a sensitivity of 28.65 ± 0.52 mV/decade, for a wide range of concentrations from 1.00 × 10-6 to 5.00 × 10-2 M, selectivity, reproducibility, stability and fast response time of 10.00 s. The proposed strontium ion sensor was used as indicator electrode in the potentiometric titration of strontium ion versus ethylenediamine tetra acetic acid [EDTA]. This comparative study has shown that ZnO nanorods possessed better performance with high sensitivity and low limit of detection due to high surface area to volume ratio as compared to the flat surface of ZnO thin films.

Enzyme-assisted cycling amplification and DNA-templated in-situ deposition of silver nanoparticles for the sensitive electrochemical detection of Hg(2.).

PubMed

Xie, Hua; Wang, Qin; Chai, Yaqin; Yuan, Yali; Yuan, Ruo

2016-12-15

In this work, a label-free electrochemical biosensor was developed for sensitive and selective detection of mercury (II) ions (Hg(2+)) based on in-situ deposition of silver nanoparticles (AgNPs) on terminal deoxynucleotidyl transferase (TdT) extended ssDNA for signal output and nicking endonuclease for cycling amplification. In the presence of target Hg(2+), the T-rich DNA (HP1) could partly fold into duplex-like structure (termed as output DNA) via T-Hg(2+)-T base pairs and thus exposed its sticky end. The sticky end of output DNA could then hybridize with 3'-PO4 terminated capture DNA (HP2) on electrode surface to form output DNA-HP2 hybridization complex with the sequence 5'-CCTCAGC-3'/3'-GGAGTCG-5' (the sequence could be recognized by nicking endonuclease Nt. BbvCI). With the introduction of Nt. BbvCI, output DNA existed in hybridization complex was released from electrode and participated in the next hybridization process, accompanying with the cleave of HP2 to expose substantial 3'-OH group, which could be extended into a long ssDNA nanotail with the aid of TdT and deoxyadenosine triphosphate (dATP). Since the long negatively charged ssDNA nanotail absorbed the positively charged silver ions on the DNA skeleton, the metallic silver could be in-situ deposited on electrode surface for electrochemical signal output upon addition of reduction regent sodium borohydride. Under optimal conditions, the developed electrochemical biosensor presented a good response to Hg(2+) with a detection limit of 3 pM (S/N=3). Furthermore, the biosensor exhibited good reproducibility and high selectivity towards other interfering ions. The proposed sensing system also showed a promising potential application in real sample analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Development and validation of a selective, sensitive and stability indicating UPLC-MS/MS method for rapid, simultaneous determination of six process related impurities in darunavir drug substance.

PubMed

A, Vijaya Bhaskar Reddy; Yusop, Zulkifli; Jaafar, Jafariah; Aris, Azmi B; Majid, Zaiton A; Umar, Khalid; Talib, Juhaizah

2016-09-05

In this study a sensitive and selective gradient reverse phase UPLC-MS/MS method was developed for the simultaneous determination of six process related impurities viz., Imp-I, Imp-II, Imp-III, Imp-IV, Imp-V and Imp-VI in darunavir. The chromatographic separation was performed on Acquity UPLC BEH C18 (50 mm×2.1mm, 1.7μm) column using gradient elution of acetonitrile-methanol (80:20, v/v) and 5.0mM ammonium acetate containing 0.01% formic acid at a flow rate of 0.4mL/min. Both negative and positive electrospray ionization (ESI) modes were operated simultaneously using multiple reaction monitoring (MRM) for the quantification of all six impurities in darunavir. The developed method was fully validated following ICH guidelines with respect to specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, robustness and sample solution stability. The method was able to quantitate Imp-I, Imp-IV, Imp-V at 0.3ppm and Imp-II, Imp-III, and Imp-VI at 0.2ppm with respect to 5.0mg/mL of darunavir. The calibration curves showed good linearity over the concentration range of LOQ to 250% for all six impurities. The correlation coefficient obtained was >0.9989 in all the cases. The accuracy of the method lies between 89.90% and 104.60% for all six impurities. Finally, the method has been successfully applied for three formulation batches of darunavir to determine the above mentioned impurities, however no impurity was found beyond the LOQ. This method is a good quality control tool for the trace level quantification of six process related impurities in darunavir during its synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

A urea biosensor based on pH-sensitive Sm2TiO5 electrolyte-insulator-semiconductor.

PubMed

Pan, Tung-Ming; Huang, Ming-De; Lin, Wan-Ying; Wu, Min-Hsien

2010-06-11

A urea biosensor based on pH-sensitive Sm(2)TiO(5) electrolyte-insulator-semiconductor (EIS) has been described. We used X-ray diffraction, Auger electron spectroscopy, and atomic force microscopy to investigate the structural and morphological features of high-k Sm(2)TiO(5) sensing membranes that had been subjected to annealing at different temperatures. The EIS device incorporating a high-k Sm(2)TiO(5) sensing film that had been annealed at 900 degrees C exhibited good sensing characteristics, including a high sensitivity of 60.5 mV/pH (in solutions from pH 2 to 12), a small hysteresis voltage of 2.72 mV (in the pH loop 7-->4-->7-->10-->7), and a low drift rate of 1.15 mV h(-1) (in the buffer solution at pH 7). The Sm(2)TiO(5) EIS device also showed a high selective response towards H(+). This improvement can be attributed to the small number of crystal defects and the large surface roughness. In addition, the urea biosensor based on pH-sensitive EIS incorporating a Sm(2)TiO(5) sensing membrane annealed at 900 degrees C allowed the potentiometric analysis of urea, at concentrations ranging from 0.1 to 32 mM, with a sensitivity of 72.85 mV/purea. Copyright 2010 Elsevier B.V. All rights reserved.

Estimation of sensitivity and specificity of brain magnetic resonance imaging and single photon emission computed tomography in the diagnosis of olfactory dysfunction after head traumas.

PubMed

Atighechi, Saeid; Zolfaghari, Aliasghar; Baradaranfar, Mohammadhossein; Dadgarnia, Mohammadhossein

2013-01-01

Olfactory dysfunction has an incidence of 5-10% after head injury. Several objective and subjective tests had been proposed. Recent studies showed that brain single photon emission computed tomography (SPECT) and brain magnetic resonance imaging (MRI) have good diagnostic value in this era in which the most common sites of involvement were olfactory bulb and olfactory nerve in MRI and frontal lobe in SPECT. This study aimed to estimate the sensitivity and specificity of brain MRI and brain SPECT in the diagnosis of traumatic hyposmia and anosmia. From February 2009 to March 2011, 63 patients with head injury and smell complaint were selected for this study. Using an identification test and a threshold smell test, 28 were anosmic and 27 had hyposmia and the remaining 8 were normosmic. All of them underwent brain MRI and SPECT. The sensitivity of SPECT was 81.5 and 85.7% in hyposmia and anosmia, respectively. Its specificity was 87.5% in anosmia and 87.7% in anosmia. MRI sensitivity was 66.7% in hyposmia but 82.1% in anosmia. Its specificity was 85.7% in anosmia and 87.7% in anosmia. If MRI and SPECT were considered together, the sensitivity was 92.3% in hyposmia and 92% in anosmia, but the specificity was 87% in both cases. According to our study, both brain MRI and SPECT have high sensitivity and specificity in the diagnosis of traumatic anosmia, although brain SPECT is slightly superior to MRI. If the two techniques are applied together, the accuracy will be increased.

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

PubMed

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

2016-12-01

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

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

PubMed

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

2018-04-17

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

A novel highly selective and sensitive detection of serotonin based on Ag/polypyrrole/Cu2O nanocomposite modified glassy carbon electrode.

PubMed

Selvarajan, S; Suganthi, A; Rajarajan, M

2018-06-01

A silver/polypyrrole/copper oxide (Ag/PPy/Cu 2 O) ternary nanocomposite was prepared by sonochemical and oxidative polymerization simple way, in which Cu 2 O was decorated with Ag nanoparticles, and covered by polyprrole (PPy) layer. The as prepared materials was characterized by UV-vis-spectroscopy (UV-vis), FT-IR, X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) with EDX, high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Sensing of serotonin (5HT) was evaluated electrocatalyst using polypyrrole/glassy carbon electrode (PPy/GCE), polypyrrole/copper oxide/glassy carbon electrode (PPy/Cu 2 O/GCE) and silver/polypyrrole/copper oxide/glassy carbon electrode (Ag/PPy/Cu 2 O/GCE). The Ag/PPy/Cu 2 O/GCE was electrochemically treated in 0.1MPBS solution through cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The peak current response increases linearly with 5-HT concentration from 0.01 to 250 µmol L -1 and the detection limit was found to be 0.0124 μmol L -1 . It exhibits high electrocatalytic activity, satisfactory repeatability, stability, fast response and good selectivity against potentially interfering species, which suggests its potential in the development of sensitive, selective, easy-operation and low-cost serotonin sensor for practical routine analyses. The proposed method is potential to expand the possible applied range of the nanocomposite material for detection of various concerned electro active substances. Copyright © 2018 Elsevier B.V. All rights reserved.

On the way to the creation of next generation photoactive materials.

PubMed

Emeline, A V; Kuznetsov, V N; Ryabchuk, V K; Serpone, N

2012-11-01

Transition from first- to second-generation photocatalysts has followed the notion that greater absorption of light in the visible region would yield greater spectral sensitivity and greater photoactivity. Though a promising strategy, in practice, it did not meet expectation because of various side issues, which in many cases has led to loss of photoactivity and chemical reactivity. This article examines some earlier notions that arose from applications of different metal oxides (e.g., TiO(2), ZnO, MgO among others) that made these oxides good photocatalysts in many processes. Phenomena that proved relevant in developing next generation photoactive materials are considered: the dependence of the activity of photocatalysts on the band gap energy, the spectral variations of the activity of photoactive materials, and the spectral variations of selectivity of photoactive materials. The tendency to decrease the energy of actinic photons through doping in forming second-generation photocatalysts is completely opposite the fundamental observation in first-generation photocatalysts whereby the activity increased with increasing band gap energy. Extension of spectral sensitivity of second-generation photoactive materials also caused a decrease of their photoactivity; hence, some notions are reconsidered to produce next(third) generation photoactive materials. The article proposes the following concepts to develop next generation photocatalysts: (1) multi(two)-photon excitation of photoactive materials with lower energy photons to achieve the same excited state as with higher energy photons, (2) utilization of heterojunctions to drive electronic processes in the desired direction, and (3) selective photoexcitation of localized electronic states to gain better selectivity.

Highly sensitive and selective microRNA detection based on DNA-bio-bar-code and enzyme-assisted strand cycle exponential signal amplification.

PubMed

Dong, Haifeng; Meng, Xiangdan; Dai, Wenhao; Cao, Yu; Lu, Huiting; Zhou, Shufeng; Zhang, Xueji

2015-04-21

Herein, a highly sensitive and selective microRNA (miRNA) detection strategy using DNA-bio-bar-code amplification (BCA) and Nb·BbvCI nicking enzyme-assisted strand cycle for exponential signal amplification was designed. The DNA-BCA system contains a locked nucleic acid (LNA) modified DNA probe for improving hybridization efficiency, while a signal reported molecular beacon (MB) with an endonuclease recognition site was designed for strand cycle amplification. In the presence of target miRNA, the oligonucleotides functionalized magnetic nanoprobe (MNP-DNA) and gold nanoprobe (AuNP-DNA) with numerous reported probes (RP) can hybridize with target miRNA, respectively, to form a sandwich structure. After sandwich structures were separated from the solution by the magnetic field, the RP were released under high temperature to recognize the MB and cleaved the hairpin DNA to induce the dissociation of RP. The dissociated RP then triggered the next strand cycle to produce exponential fluorescent signal amplification for miRNA detection. Under optimized conditions, the exponential signal amplification system shows a good linear range of 6 orders of magnitude (from 0.3 pM to 3 aM) with limit of detection (LOD) down to 52.5 zM, while the sandwich structure renders the system with high selectivity. Meanwhile, the feasibility of the proposed strategy for cell miRNA detection was confirmed by analyzing miRNA-21 in HeLa lysates. Given the high-performance for miRNA analysis, the strategy has a promising application in biological detection and in clinical diagnosis.

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

Rationally Designed Sensing Selectivity and Sensitivity of an Aerolysin Nanopore via Site-Directed Mutagenesis.

PubMed

Wang, Ya-Qian; Cao, Chan; Ying, Yi-Lun; Li, Shuang; Wang, Ming-Bo; Huang, Jin; Long, Yi-Tao

2018-04-27

Selectivity and sensitivity are two key parameters utilized to describe the performance of a sensor. In order to investigate selectivity and sensitivity of the aerolysin nanosensor, we manipulated its surface charge at different locations via single site-directed mutagenesis. To study the selectivity, we replaced the positively charged R220 at the entrance of the pore with negatively charged glutamic acid, resulting in barely no current blockages for sensing negatively charged oligonucleotides. For the sensitivity, we substituted the positively charged lumen-exposed amino acid K238 located at trans-ward third of the β-barrel stem with glutamic acid. This leads to a surprisingly longer duration time at +140 mV, which is about 20 times slower in translocation speed for Poly(dA) 4 compared to that of wild-type aerolysin, indicating the stronger pore-analyte interactions and enhanced sensitivity. Therefore, it is both feasible and understandable to rationally design confined biological nanosensors for single molecule detection with high selectivity and sensitivity.

Algorithm for identifying and separating beats from arterial pulse records

PubMed Central

Treo, Ernesto F; Herrera, Myriam C; Valentinuzzi, Max E

2005-01-01

Background This project was designed as an epidemiological aid-selecting tool for a small country health center with the general objective of screening out possible coronary patients. Peripheral artery function can be non-invasively evaluated by impedance plethysmography. Changes in these vessels appear as good predictors of future coronary behavior. Impedance plethysmography detects volume variations after simple occlusive maneuvers that may show indicative modifications in arterial/venous responses. Averaging of a series of pulses is needed and this, in turn, requires proper determination of the beginning and end of each beat. Thus, the objective here is to describe an algorithm to identify and separate out beats from a plethysmographic record. A secondary objective was to compare the output given by human operators against the algorithm. Methods The identification algorithm detected the beat's onset and end on the basis of the maximum rising phase, the choice of possible ventricular systolic starting points considering cardiac frequency, and the adjustment of some tolerance values to optimize the behavior. Out of 800 patients in the study, 40 occlusive records (supradiastolic- subsystolic) were randomly selected without any preliminary diagnosis. Radial impedance plethysmographic pulse and standard ECG were recorded digitizing and storing the data. Cardiac frequency was estimated with the Power Density Function and, thereafter, the signal was derived twice, followed by binarization of the first derivative and rectification of the second derivative. The product of the two latter results led to a weighing signal from which the cycles' onsets and ends were established. Weighed and frequency filters are needed along with the pre-establishment of their respective tolerances. Out of the 40 records, 30 seconds strands were randomly chosen to be analyzed by the algorithm and by two operators. Sensitivity and accuracy were calculated by means of the true/false and positive/negative criteria. Synchronization ability was measured through the coefficient of variation and the median value of correlation for each patient. These parameters were assessed by means of Friedman's ANOVA and Kendall Concordance test. Results Sensitivity was 97% and 91% for the two operators, respectively, while accuracy was cero for both of them. The synchronism variability analysis was significant (p < 0.01) for the two statistics, showing that the algorithm produced the best result. Conclusion The proposed algorithm showed good performance as expressed by its high sensitivity. The correlation analysis demonstrated that, from the synchronism point of view, the algorithm performed the best detection. Patients with marked arrhythmic processes are not good candidates for this kind of analysis. At most, they would be singled out by the algorithm and, thereafter, to be checked by an operator. PMID:16095532

Selecting a Good Conference Location Based on Participants' Interests

ERIC Educational Resources Information Center

Miah, Muhammed

2011-01-01

Selecting a good conference location within budget constraints to attract paper authors and participants is a very difficult job for the conference organizers. A conference location is also very important along with other issues such as ranking of the conference. Selecting a bad conference location may reduce the number of paper submissions and…

Impact of nitrogen doping of niobium superconducting cavities on the sensitivity of surface resistance to trapped magnetic flux

NASA Astrophysics Data System (ADS)

Gonnella, Dan; Kaufman, John; Liepe, Matthias

2016-02-01

Future particle accelerators such as the SLAC "Linac Coherent Light Source-II" (LCLS-II) and the proposed Cornell Energy Recovery Linac require hundreds of superconducting radio-frequency (SRF) niobium cavities operating in continuous wave mode. In order to achieve economic feasibility of projects such as these, the cavities must achieve a very high intrinsic quality factor (Q0) to keep cryogenic losses within feasible limits. To reach these high Q0's in the case of LCLS-II, nitrogen-doping of niobium cavities has been selected as the cavity preparation technique. When dealing with Q0's greater than 1 × 1010, the effects of ambient magnetic field on Q0 become significant. Here, we show that the sensitivity to RF losses from trapped magnetic field in a cavity's walls is strongly dependent on the cavity preparation. Specifically, standard electropolished and 120 °C baked cavities show a sensitivity of residual resistance from trapped magnetic flux of ˜0.6 and ˜0.8 nΩ/mG trapped, respectively, while nitrogen-doped cavities show a higher sensitivity of residual resistance from trapped magnetic flux of ˜1 to 5 nΩ/mG trapped. We show that this difference in sensitivities is directly related to the mean free path of the RF surface layer of the niobium: shorter mean free paths lead to less sensitivity of residual resistance to trapped magnetic flux in the dirty limit (ℓ ≪ ξ0), while longer mean free paths lead to lower sensitivity of residual resistance to trapped magnetic flux in the clean limit (ℓ ≫ ξ0). These experimental results are also shown to have good agreement with recent theoretical predictions for pinned vortex lines oscillating in RF fields.

Enhanced Sensitive Immunoassay: Noncompetitive Phage Anti-Immune Complex Assay for the Determination of Malachite Green and Leucomalachite Green

PubMed Central

2015-01-01

To develop a more sensitive immunoassay for malachite green (MG) and leucomalachite green (LMG), we identified the immunocomplex binding phage-borne peptides for use in the noncompetitive phage anti-immunocomplex assay (PHAIA). An anti-LMG monoclonal antibody (mAb) was used to select immunocomplex binding peptides from a circular random eight-amino-acid phage-displayed library. After three rounds of panning-elution, five peptides that bound the LMG–mAb immunocomplex were obtained. One of the phage-borne peptide clones that resulted in an assay with the highest sensitivity was chosen for further research. The concentration of LMG producing 50% of the saturated signal and the limit of detection of the assay were 7.02 and 0.55 ng/mL, respectively, with a linear range of 1.35 to 21.56 ng/mL. The PHAIA based on the same antibody was 16 times more sensitive compared to the competitive immunoassay. PHAIA was used to analyze LMG, MG, and two mixtures of spiked fish samples, with validation by high-performance liquid chromatography (HPLC) with fluorescence detector. Results showed a good correlation (R2LMG = 0.9841; R2MG = 0.993; R2Mixture = 0.9903) between the data of PHAIA and HPLC, thus the assay was an efficient method for monitoring food safety. PMID:25077381

A methodology to estimate uncertainty for emission projections through sensitivity analysis.

PubMed

Lumbreras, Julio; de Andrés, Juan Manuel; Pérez, Javier; Borge, Rafael; de la Paz, David; Rodríguez, María Encarnación

2015-04-01

Air pollution abatement policies must be based on quantitative information on current and future emissions of pollutants. As emission projections uncertainties are inevitable and traditional statistical treatments of uncertainty are highly time/resources consuming, a simplified methodology for nonstatistical uncertainty estimation based on sensitivity analysis is presented in this work. The methodology was applied to the "with measures" scenario for Spain, concretely over the 12 highest emitting sectors regarding greenhouse gas and air pollutants emissions. Examples of methodology application for two important sectors (power plants, and agriculture and livestock) are shown and explained in depth. Uncertainty bands were obtained up to 2020 by modifying the driving factors of the 12 selected sectors and the methodology was tested against a recomputed emission trend in a low economic-growth perspective and official figures for 2010, showing a very good performance. A solid understanding and quantification of uncertainties related to atmospheric emission inventories and projections provide useful information for policy negotiations. However, as many of those uncertainties are irreducible, there is an interest on how they could be managed in order to derive robust policy conclusions. Taking this into account, a method developed to use sensitivity analysis as a source of information to derive nonstatistical uncertainty bands for emission projections is presented and applied to Spain. This method simplifies uncertainty assessment and allows other countries to take advantage of their sensitivity analyses.

Highly sensitive catalytic spectrophotometric determination of ruthenium

NASA Astrophysics Data System (ADS)

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

2008-01-01

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

A gas chromatography-mass spectrometry assay to quantify camphor extracted from goat serum.

PubMed

Lee, Kyung-Min; Dai, Susie Y; Herrman, Timothy J; Musser, Jeffrey M B

2012-09-15

A sensitive gas chromatography-mass spectrometry (GC-MS) method was developed and validated for quantification and pharmacokinetics of camphor, a major monoterpene of juniper plant, in goat serum. Camphor and internal standard (terpinolene) eluates from solid phase extraction (SPE) with ethyl acetate yielded well resolved peaks and were clearly identified in total and selected ion chromatograms. The elution and injection volumes were optimized for improved detection and quantification of camphor based on peak shape, signal to noise ratio, recoveries, and repeatability. The matrix calibration curve with the good linearity (R(2)=0.998) and response in the range of 0.005-10.0 μg/mL was used to determine camphor concentration in goat serum. The GC-MS method offered sufficiently low limits of detection (1 ng/mL) and quantitation (3 ng/mL) for camphor concentration in goat serum for the pharmacokinetic study. The proposed method showed good intra- and inter-day variation with relative standard deviation (RSD) of 0.2-7.7% and produced good recovery (96.0-111.6%) and reproducibility (1.6-6.1%) at all spiked levels. Using this method on serum samples obtained from two goats orally dosed with camphor confirmed that the method is suitable for camphor studies in animals. Copyright © 2012 Elsevier B.V. All rights reserved.

Packed in-tube solid phase microextraction with graphene oxide supported on aminopropyl silica: Determination of target triazines in water samples.

PubMed

De Toffoli, Ana L; Fumes, Bruno H; Lanças, Fernando M

2018-02-22

On-line in-tube solid phase microextraction (in-tube SPME) coupled to high performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS) was successfully applied to the determination of selected triazines in water samples. The method based on the employment of a packed column containing graphene oxide (GO) supported on aminopropyl silica (Si) showed that the extraction phase has a high potential for triazines extraction aiming to its physical-chemical properties including ultrahigh specific surface area, good mechanical and thermal stability and high fracture strength. Injection volume and loading time were both investigated and optimized. The method validation using Si-GO to extract and concentrate the analytes showed satisfactory results, good sensitivity, good linearity (0.2-4.0 µg L -1 ) and low detection limits (1.1-2.9 ng L -1 ). The high extraction efficiency was determined with enrichment factors ranging from 1.2-2.9 for the lowest level, 1.3-4.9 intermediate level and 1.2-3.0 highest level (n = 3). Although the analytes were not detected in the real samples evaluated, the method has demonstrated to be efficient through its application in the analysis of spiked triazines in ground and mineral water samples.

Target immobilization as a strategy for NMR-based fragment screening: comparison of TINS, STD, and SPR for fragment hit identification.

PubMed

Kobayashi, Masakazu; Retra, Kim; Figaroa, Francis; Hollander, Johan G; Ab, Eiso; Heetebrij, Robert J; Irth, Hubertus; Siegal, Gregg

2010-09-01

Fragment-based drug discovery (FBDD) has become a widely accepted tool that is complementary to high-throughput screening (HTS) in developing small-molecule inhibitors of pharmaceutical targets. Because a fragment campaign can only be as successful as the hit matter found, it is critical that the first stage of the process be optimized. Here the authors compare the 3 most commonly used methods for hit discovery in FBDD: high concentration screening (HCS), solution ligand-observed nuclear magnetic resonance (NMR), and surface plasmon resonance (SPR). They selected the commonly used saturation transfer difference (STD) NMR spectroscopy and the proprietary target immobilized NMR screening (TINS) as representative of the array of possible NMR methods. Using a target typical of FBDD campaigns, the authors find that HCS and TINS are the most sensitive to weak interactions. They also find a good correlation between TINS and STD for tighter binding ligands, but the ability of STD to detect ligands with affinity weaker than 1 mM K(D) is limited. Similarly, they find that SPR detection is most suited to ligands that bind with K(D) better than 1 mM. However, the good correlation between SPR and potency in a bioassay makes this a good method for hit validation and characterization studies.

Development of a novel tridentate ligand for colorimetric detection of Mn2+ based on AgNPs.

PubMed

Wei, Jianyu; Chen, Jinfan; Yue, Guozong; Hu, Liangsheng; Zhao, Danqing; Zhu, Jing; Yang, Luming; Huang, Deshun; Zhao, Pengxiang

2018-05-09

A novel tridentate ligand nitrilotris(methylene)tris(1,2,3-triazole)triacetate (NTTTA) has been synthesized by click reaction and followed with ester hydrolysis reaction. The silver nanoparticles (AgNPs) were then modified and stabilized by this ligand, and subsequently been employed for the highly selective and sensitive colorimetric detection of Mn 2+ in aqueous solution. The presence of Mn 2+ can cause the aggregation of AgNPs, which leads to the color change of the dispersion from yellow to brown, as well as the decrease and red-shift of the surface plasmon resonance absorption. The detection limit of Mn 2+ was as approximately 0.5 μM by the naked eyes. UV-vis spectroscopy analysis showed a good linear relationship between the logarithm of the ratios (A 550 /A 395 ) and the concentration of Mn 2+ over the range of 0.05 μM-10 μM, and the LOD was calculated to be 12.6 nM (S/N = 3). The present assay showed good simplicity without the need of adjusting the pH value. The feasibility of this technique was evaluated for successful detection of Mn 2+ in tap water and lake water samples, with good recoveries. Copyright © 2018 Elsevier B.V. All rights reserved.

Plasticizer Effects in the PVC Membrane of the Dibasic Phosphate Selective Electrode

PubMed Central

Carey, Clifton

2016-01-01

The PVC membrane of an ion-selective electrode (ISE) sensitive to dibasic phosphate ions (HPO4-ISE) has not been optimized for maximum selectivity, sensitivity, and useable ISE lifetime and further work was necessary to improve its performance. Two areas of investigation are reported here: include the parameters for the lipophilicity of the plasticizer compound used and the amount of cyclic polyamine ionophore incorporated in the PVC membrane. Six candidate plasticizers with a range of lipophilicity were evaluated for their effect on the useable lifetime, sensitivity, and selectivity of the ISE against 13 different anions. Selectivity was determined by a modified fixed interferent method, sensitivity was determined without interferents, and the usable lifetime evaluated at the elapsed time where 50% of the HPO4-ISE failed (L50). The results show that choosing a plasticizer that has a lipophilicity similar to the ionophore's results in the best selectivity and sensitivity and the longest L50. PMID:27347487

Visual discrimination of dihydroxybenzene isomers based on a nitrogen-doped graphene quantum dot-silver nanoparticle hybrid

NASA Astrophysics Data System (ADS)

Shi, Bingfang; Su, Yubin; Zhao, Jingjin; Liu, Rongjun; Zhao, Yan; Zhao, Shulin

2015-10-01

A room temperature reducing agent-free strategy for the synthesis of a nitrogen-doped graphene quantum dot-silver nanoparticle (N-GQD/AgNP) hybrid was presented. In this strategy, N-GQDs were used as a reducing agent and stabilizer for the formation of the N-GQD/AgNP hybrid, and the formation of the N-GQD/AgNP hybrid may result from the extraordinary reduction properties of N-GQDs, which are attributed to the nature of the surface oxygen-containing functional groups. The N-GQD/AgNP hybrid exhibits good dispersity and outstanding catalytic ability toward the oxidation of catechol (CC) and hydroquinone (HQ) by Ag+. In the presence of the N-GQD/AgNP hybrid, the reduction of Ag+ by CC and HQ was improved. CC enhanced the absorbance of the N-GQD/AgNP-Ag+ system the most, and HQ followed, while resorcinol (RC) had only a little effect on the absorption intensity of the system. Thus, a sensitive and selective colorimetric sensing method based on the N-GQD/AgNP-Ag+ system was developed for the discrimination of CC, HQ and RC. A good linear relationship was obtained from 0.1 to 15.0 μM for CC and from 0.3 to 20.0 μM for HQ. The detection limits of CC and HQ were 0.03 and 0.1 μM, respectively. In addition, the proposed method also shows a high selectivity for the detection of CC and HQ, and appreciable changes in color of the N-GQD/AgNP-Ag+ system toward CC, RC and HQ were observed.A room temperature reducing agent-free strategy for the synthesis of a nitrogen-doped graphene quantum dot-silver nanoparticle (N-GQD/AgNP) hybrid was presented. In this strategy, N-GQDs were used as a reducing agent and stabilizer for the formation of the N-GQD/AgNP hybrid, and the formation of the N-GQD/AgNP hybrid may result from the extraordinary reduction properties of N-GQDs, which are attributed to the nature of the surface oxygen-containing functional groups. The N-GQD/AgNP hybrid exhibits good dispersity and outstanding catalytic ability toward the oxidation of catechol (CC) and hydroquinone (HQ) by Ag+. In the presence of the N-GQD/AgNP hybrid, the reduction of Ag+ by CC and HQ was improved. CC enhanced the absorbance of the N-GQD/AgNP-Ag+ system the most, and HQ followed, while resorcinol (RC) had only a little effect on the absorption intensity of the system. Thus, a sensitive and selective colorimetric sensing method based on the N-GQD/AgNP-Ag+ system was developed for the discrimination of CC, HQ and RC. A good linear relationship was obtained from 0.1 to 15.0 μM for CC and from 0.3 to 20.0 μM for HQ. The detection limits of CC and HQ were 0.03 and 0.1 μM, respectively. In addition, the proposed method also shows a high selectivity for the detection of CC and HQ, and appreciable changes in color of the N-GQD/AgNP-Ag+ system toward CC, RC and HQ were observed. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04659a

An active fluorescent probe based on aggregation-induced emission for intracellular bioimaging of Zn2+ and tracking of interactions with single-stranded DNA.

PubMed

Wen, Xiaoye; Wang, Qi; Fan, Zhefeng

2018-07-12

A novel dual-sensing fluorescence probe L was designed and synthesized for highly selective and sensitive detection of Zn 2+ and DNA. The probe L achieved a detection limit of 3.8 nM for Zn 2+ , which is lower than the acceptable level of Zn 2+ in living cells. The probe L displayed high selectivity toward Zn 2+ over other interference metal ions and amino acids. Moreover, the probe L displayed low cytotoxicity and good cell permeability, indicating its potential for detecting and bio-imaging of Zn 2+ . In addition, the probe L-Zn 2+ exhibited enhanced fluorescence signal for DNA detection through the metal-coordination interaction between Zn 2+ and DNA. The enhanced signal is higher than that of the classical ethidium bromide probe. The experiments in aqueous media verified the feasibility of applying probe L in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Design of a New Ultracompact Resonant Plasmonic Multi-Analyte Label-Free Biosensing Platform

PubMed Central

De Palo, Maripina; Ciminelli, Caterina

2017-01-01

In this paper, we report on the design of a bio-multisensing platform for the selective label-free detection of protein biomarkers, carried out through a 3D numerical algorithm. The platform includes a number of biosensors, each of them is based on a plasmonic nanocavity, consisting of a periodic metal structure to be deposited on a silicon oxide substrate. Light is strongly confined in a region with extremely small size (=1.57 μm2), to enhance the light-matter interaction. A surface sensitivity Ss = 1.8 nm/nm has been calculated together with a detection limit of 128 pg/mm2. Such performance, together with the extremely small footprint, allow the integration of several devices on a single chip to realize extremely compact lab-on-chip microsystems. In addition, each sensing element of the platform has a good chemical stability that is guaranteed by the selection of gold for its fabrication. PMID:28783075

Potassium permanganate-glutaraldehyde chemiluminescence system catalyzed by gold nanoprisms toward selective determination of fluoride.

PubMed

Abolhasani, Jafar; Hassanzadeh, Javad; Ghorbani-Kalhor, Ebrahim

2016-02-01

Gold and silver nanoparticles (NPs) are shown to exert a positive effect on the chemiluminescence (CL) reaction of permanganate aldehydes. Interestingly, between various shapes examined, Au nanoprisms have the highest beneficial effect. This effect is even more notable in the presence of sodium dodecyl sulfate (SDS) surfactant. UV-vis spectra and transmission electron microscopy were used to characterize the NP shapes and sizes. Furthermore, it was observed that iron(III) ions can slightly increase CL emission of this system. This intensification is very effective in the presence of fluoride ions (F(-)). These observations form the basis of the method for the high sensitive determination of F(-) in the 6-1200 nmol L(-1) concentration range, with a detection limit of 2.1 nmol L(-1). The proposed method has good precision and was satisfactorily used in the selective determination of low concentrations of fluoride ion in real samples. Copyright © 2015 John Wiley & Sons, Ltd.

Ultrasensitive Sample Quantitation via Selected Reaction Monitoring Using CITP/CZE-ESI-Triple Quadrupole MS

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

Wang, Chenchen; Lee, Cheng S.; Smith, Richard D.

2012-11-10

We demonstrate the direct coupling of transient capillary isotachophoresis/ capillary zone electrophoresis (CITP/CZE) with a high sensitivity triple quadrupole mass spectrometer operating in selected reaction monitoring (SRM) mode for sample quantitation. The capability of CITP/CZE for in situ sample enrichment and separation has been shown to significantly improve the analytical figures of merit. A linear dynamic range spanning more than 4 orders of magnitude was observed. An average signal-to-noise ratio (S/N) of 49.6 was observed for 50 attomoles of targeted peptide in the presence of a complex and much more abundant bovine serum albumin (BSA) digest products. A correlation ofmore » variation (CV) less than 10 % for peak area was measured from triplicate sample analyses at 50 pM peptide concentration, showing good reproducibility of this online CITP/CZE-SRM mass spectrometry (MS) platform, and with limit of quantitation (LOQ) demonstrated to be well below 50 pM.« less

A micrometer-sized europium(iii)-organic framework for selective sensing of the Cr2O72- anion and picric acid in water systems.

PubMed

He, Hongming; Chen, Si-Hang; Zhang, De-Yu; Hao, Rui; Zhang, Chao; Yang, En-Cui; Zhao, Xiao-Jun

2017-10-10

A micrometer-sized europium(iii)-organic framework with asymmetric binuclear metal subunits extended by 4,5-dichlorophthalaten (DCPA), [Eu 2 (H 2 O)(DCPA) 3 ] n , was easily obtained using a reverse microemulsion method. The framework exhibits good dispersibility, excellent thermal and environmental stability and easy regeneration ability. More importantly, the complex displays strong red emission and can selectively and sensitively detect both inorganic Cr 2 O 7 2- anions (K sv = 8.7 × 10 3 M -1 ) and organic picric acid contaminants (K sv = 1.07 × 10 4 M -1 ) in water systems through fluorescence quenching. A luminescent film of 1 was further prepared and successfully used to detect the Cr 2 O 7 2- anion in an aqueous system. These interesting results indicate that the well-dispersed europium(iii)-organic framework can serve as a promising dual-responsive luminescent sensor for environmental pollutant monitoring.

Silver nanoparticles-based colorimetric array for the detection of Thiophanate-methyl

NASA Astrophysics Data System (ADS)

Zheng, Mingda; Wang, Yingying; Wang, Chenge; Wei, Wei; Ma, Shuang; Sun, Xiaohan; He, Jiang

2018-06-01

A simple and selective colorimetric sensor based on citrate capped silver nanoparticles (Cit-AgNPs) is proposed for the detection of Thiophanate-methyl (TM) with high sensitivity and selectivity. The method based on the color change of Cit-AgNPs from yellow to cherry red with the addition of TM to Cit-AgNPs that caused a red-shift on the surface plasmon resonance (SPR) band from 394 nm to 525 nm due to the hydrogen-bonding and substitution. The density functional theory (DFT) method was also calculated the interactions between the TM and citrate ions. Under the optimized conditions, a linear relationship between the absorption ratio (A525nm/A394nm) and TM concentration was found in the range of 2-100 μM with correlation coefficient (R2) of 0.988. The detection limit of TM was 0.12 μM by UV-vis spectrometer. Moreover, the applicability of colorimetric sensor is successfully verified by the detection of TM in environmental samples with good recoveries.

Validation of different measures of insulin sensitivity of glucose metabolism in dairy cows using the hyperinsulinemic euglycemic clamp test as the gold standard.

PubMed

De Koster, J; Hostens, M; Hermans, K; Van den Broeck, W; Opsomer, G

2016-10-01

The aim of the present research was to compare different measures of insulin sensitivity in dairy cows at the end of the dry period. To do so, 10 clinically healthy dairy cows with a varying body condition score were selected. By performing hyperinsulinemic euglycemic clamp (HEC) tests, we previously demonstrated a negative association between the insulin sensitivity and insulin responsiveness of glucose metabolism and the body condition score of these animals. In the same animals, other measures of insulin sensitivity were determined and the correlation with the HEC test, which is considered as the gold standard, was calculated. Measures derived from the intravenous glucose tolerance test (IVGTT) are based on the disappearance of glucose after an intravenous glucose bolus. Glucose concentrations during the IVGTT were used to calculate the area under the curve of glucose and the clearance rate of glucose. In addition, glucose and insulin data from the IVGTT were fitted in the minimal model to derive the insulin sensitivity parameter, Si. Based on blood samples taken before the start of the IVGTT, basal concentrations of glucose, insulin, NEFA, and β-hydroxybutyrate were determined and used to calculate surrogate indices for insulin sensitivity, such as the homeostasis model of insulin resistance, the quantitative insulin sensitivity check index, the revised quantitative insulin sensitivity check index and the revised quantitative insulin sensitivity check index including β-hydroxybutyrate. Correlation analysis revealed no association between the results obtained by the HEC test and any of the surrogate indices for insulin sensitivity. For the measures derived from the IVGTT, the area under the curve for the first 60 min of the test and the Si derived from the minimal model demonstrated good correlation with the gold standard. Copyright © 2016 Elsevier Inc. All rights reserved.

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.

Selection on Inversion Breakpoints Favors Proximity to Pairing Sensitive Sites in Drosophila melanogaster

PubMed Central

Corbett-Detig, Russell B.

2016-01-01

Chromosomal inversions are widespread among taxa, and have been implicated in a number of biological processes including adaptation, sex chromosome evolution, and segregation distortion. Consistent with selection favoring linkage between loci, it is well established that length is a selected trait of inversions. However, the factors that affect the distribution of inversion breakpoints remain poorly understood. “Sensitive sites” have been mapped on all euchromatic chromosome arms in Drosophila melanogaster, and may be a source of natural selection on inversion breakpoint positions. Briefly, sensitive sites are genomic regions wherein proximal structural rearrangements result in large reductions in local recombination rates in heterozygotes. Here, I show that breakpoints of common inversions are significantly more likely to lie within a cytological band containing a sensitive site than are breakpoints of rare inversions. Furthermore, common inversions for which neither breakpoint intersects a sensitive site are significantly longer than rare inversions, but common inversions whose breakpoints intersect a sensitive site show no evidence for increased length. I interpret these results to mean that selection favors inversions whose breakpoints disrupt synteny near to sensitive sites, possibly because these inversions suppress recombination in large genomic regions. To my knowledge this is the first evidence consistent with positive selection acting on inversion breakpoint positions. PMID:27343234

Selection on Inversion Breakpoints Favors Proximity to Pairing Sensitive Sites in Drosophila melanogaster.

PubMed

Corbett-Detig, Russell B

2016-09-01

Chromosomal inversions are widespread among taxa, and have been implicated in a number of biological processes including adaptation, sex chromosome evolution, and segregation distortion. Consistent with selection favoring linkage between loci, it is well established that length is a selected trait of inversions. However, the factors that affect the distribution of inversion breakpoints remain poorly understood. "Sensitive sites" have been mapped on all euchromatic chromosome arms in Drosophila melanogaster, and may be a source of natural selection on inversion breakpoint positions. Briefly, sensitive sites are genomic regions wherein proximal structural rearrangements result in large reductions in local recombination rates in heterozygotes. Here, I show that breakpoints of common inversions are significantly more likely to lie within a cytological band containing a sensitive site than are breakpoints of rare inversions. Furthermore, common inversions for which neither breakpoint intersects a sensitive site are significantly longer than rare inversions, but common inversions whose breakpoints intersect a sensitive site show no evidence for increased length. I interpret these results to mean that selection favors inversions whose breakpoints disrupt synteny near to sensitive sites, possibly because these inversions suppress recombination in large genomic regions. To my knowledge this is the first evidence consistent with positive selection acting on inversion breakpoint positions. Copyright © 2016 by the Genetics Society of America.

Development of Neural Sensitivity to Face Identity Correlates with Perceptual Discriminability

PubMed Central

Barnett, Michael A.; Hartley, Jake; Gomez, Jesse; Stigliani, Anthony; Grill-Spector, Kalanit

2016-01-01

Face perception is subserved by a series of face-selective regions in the human ventral stream, which undergo prolonged development from childhood to adulthood. However, it is unknown how neural development of these regions relates to the development of face-perception abilities. Here, we used functional magnetic resonance imaging (fMRI) to measure brain responses of ventral occipitotemporal regions in children (ages, 5–12 years) and adults (ages, 19–34 years) when they viewed faces that parametrically varied in dissimilarity. Since similar faces generate lower responses than dissimilar faces due to fMRI adaptation, this design objectively evaluates neural sensitivity to face identity across development. Additionally, a subset of subjects participated in a behavioral experiment to assess perceptual discriminability of face identity. Our data reveal three main findings: (1) neural sensitivity to face identity increases with age in face-selective but not object-selective regions; (2) the amplitude of responses to faces increases with age in both face-selective and object-selective regions; and (3) perceptual discriminability of face identity is correlated with the neural sensitivity to face identity of face-selective regions. In contrast, perceptual discriminability is not correlated with the amplitude of response in face-selective regions or of responses of object-selective regions. These data suggest that developmental increases in neural sensitivity to face identity in face-selective regions improve perceptual discriminability of faces. Our findings significantly advance the understanding of the neural mechanisms of development of face perception and open new avenues for using fMRI adaptation to study the neural development of high-level visual and cognitive functions more broadly. SIGNIFICANCE STATEMENT Face perception, which is critical for daily social interactions, develops from childhood to adulthood. However, it is unknown what developmental changes in the brain lead to improved performance. Using fMRI in children and adults, we find that from childhood to adulthood, neural sensitivity to changes in face identity increases in face-selective regions. Critically, subjects' perceptual discriminability among faces is linked to neural sensitivity: participants with higher neural sensitivity in face-selective regions demonstrate higher perceptual discriminability. Thus, our results suggest that developmental increases in face-selective regions' sensitivity to face identity improve perceptual discrimination of faces. These findings significantly advance understanding of the neural mechanisms underlying the development of face perception and have important implications for assessing both typical and atypical development. PMID:27798143

Nanoparticle-Based Immunochromatographic Test Strip with Fluorescent Detector for Quantification of Phosphorylated Acetycholinesterase: An Exposure Biomarker of Organophosphorous Agents

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

Zhang, Weiying; Ge, Xiaoxiao; Tang, Yong

A nanoparticle-based fluorescence immunochromatographic test strip (FITS) coupled with a hand-held detector for highly selective and sensitive detection of phosphorylated acetylcholinesterase (AChE), an exposure biomarker of organophosphate (OP) pesticides and nerve agents, is reported. In this approach, OP-AChE adducts were selectively captured by quantum dot-tagged anti-AChE antibodies (Qdot-anti-AChE) and zirconia nanoparticles (ZrO2 NPs). The sandwich-like immunoreactions were performed among the Qdot-anti-AChE, OP-AChE and ZrO2 NPs to form Qdot-anti-AChE/OP-AChE/ZrO2 complex, which was detected by recording the fluorescence intensity of Qdot captured on the test line. Paraoxon was used as the model OP pesticides. Under optimal conditions, this portable FITS immunosensor demonstratesmore » a highly linear absorption response over the range of 0.01 nM to 10 nM OP-AChE, with a detection limit of 4 pM, coupled with a good reproducibility. Moreover, the FITS immunosensor has been validated with OP-AChE spiked human plasma samples. This is the first report on the development of ZrO2 NPs-based FITS for detection of OP-AChE adduct. The FITS immunosensor provides a sensitive and low-cost sensing platform for on-site screening/evaluating OP pesticides and nerve agents poisoning.« less

Bacteriophage-Fused Peptides for Serodiagnosis of Human Strongyloidiasis

PubMed Central

Feliciano, Nágilla Daliane; Ribeiro, Vanessa da Silva; Santos, Fabiana de Almeida Araújo; Fujimura, Patricia Tiemi; Gonzaga, Henrique Tomaz; Goulart, Luiz Ricardo; Costa-Cruz, Julia Maria

2014-01-01

Background Strongyloidiasis, a human intestinal infection caused by the nematode Strongyloides stercoralis, is frequently underdiagnosed and although its high prevalence is still a neglected parasitic disease because conventional diagnostic tests based on parasitological examination (presence of Strongyloides larvae in stool) are not sufficiently sensitive due to the low parasitic load and to the irregular larval output. There is an urgent need to improve diagnostic assays, especially for immunocompromised patients with high parasitic load as consequence of self-infection cycle, which can disseminate throughout the body, resulting in a potentially fatal hyperinfection syndrome often accompanied by sepsis or meningitis. Methods/Principal Findings We have performed Phage Display technology to select peptides that mimic S. stercoralis antigens, capable of detecting a humoral response in patients with strongyloidiasis. The peptides reactivity was investigated by Phage-ELISA through different panels of serum samples. We have successfully selected five peptides with significant immunoreactivity to circulating IgG from patients' sera with strongyloidiasis. The phage displayed peptides C9 and C10 presented the highest diagnostic potential (AUC>0.87) with excellent sensitivity (>85%) and good specificity (>77.5%), suggesting that some S. stercoralis antigens trigger systemic immune response. Conclusions/Significance These novel antigens are interesting serum biomarkers for routine strongyloidiasis screenings due to the easy production and simple assay using Phage-ELISA. Such markers may also present a promising application for therapeutic monitoring. PMID:24874206

Selective voltammetric determination of Cd(II) by using N,S-codoped porous carbon nanofibers.

PubMed

Gao, Sanshuang; Liu, Jing; Luo, Jun; Mamat, Xamxikamar; Sambasivam, Sangaraju; Li, Yongtao; Hu, Xun; Wågberg, Thomas; Hu, Guangzhi

2018-05-05

Porous carbon nanofibers codoped with nitrogen and sulfur (NFs) were prepared by pyrolysis of trithiocyanuric acid, silica nanospheres and polyacrylonitrile (PAN) followed by electrospinning. The NFs were used to modify a glassy carbon electrode (GCE) which then displayed highly sensitive response to traces of Cd(II). Compared to a bare GCE and a Nafion modified GCE, the GCE modified with codoped NFs shows improved sensitivity for Cd(II) in differential pulse anodic sweep voltammetry. The stripping peak current (typically measured at 0.81 V vs. Ag/AgCl) increases linearly in the 2.0-500 μg·L -1 Cd(II) concentration range. This is attributed to the large surface area (109 m 2 ·g -1 ), porous structure, and high fraction of heteroatoms (19 at.% of N and 0.75 at.% of S). The method was applied to the determination of Cd(II) in (spiked) tap water where it gave recoveries that ranged between 96% and 103%. Graphical abstract Schematic of a glassy carbon electrode (GCE) modified with N- and S-codoped porous carbon nanofibers (N,S-PCNFs). This GCE has good selectivity for cadmium ion (Cd 2+ ) which can be determined by differential pulse anodic sweeping voltammetry (DPASV) with a detection limit as low as 0.7 ng·mL -1 .

Optimization of a sensitive method for the determination of nitro musk fragrances in waters by solid-phase microextraction and gas chromatography with micro electron capture detection using factorial experimental design.

PubMed

Polo, Maria; Garcia-Jares, Carmen; Llompart, Maria; Cela, Rafael

2007-08-01

A solid-phase microextraction method (SPME) followed by gas chromatography with micro electron capture detection for determining trace levels of nitro musk fragrances in residual waters was optimized. Four nitro musks, musk xylene, musk moskene, musk tibetene and musk ketone, were selected for the optimization of the method. Factors affecting the extraction process were studied using a multivariate approach. Two extraction modes (direct SPME and headspace SPME) were tried at different extraction temperatures using two fiber coatings [Carboxen-polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane-divinylbenzene (PDMS/DVB)] selected among five commercial tested fibers. Sample agitation and the salting-out effect were also factors studied. The main effects and interactions between the factors were studied for all the target compounds. An extraction temperature of 100 degrees C and sampling the headspace over the sample, using either CAR/PDMS or PDMS/DVB as fiber coatings, were found to be the experimental conditions that led to a more effective extraction. High sensitivity, with detection limits in the low nanogram per liter range, and good linearity and repeatability were achieved for all nitro musks. Since the method proposed performed well for real samples, it was applied to different water samples, including wastewater and sewage, in which some of the target compounds (musk xylene and musk ketone) were detected and quantified.

Molecularly Imprinted Core-Shell CdSe@SiO2/CDs as a Ratiometric Fluorescent Probe for 4-Nitrophenol Sensing

NASA Astrophysics Data System (ADS)

Liu, Mingyue; Gao, Zhao; Yu, Yanjun; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

2018-01-01

4-Nitrophenol (4-NP) is a priority pollutant in water and is both carcinogenic and genotoxic to humans and wildlife even at very low concentrations. Thus, we herein fabricated a novel molecularly imprinted core-shell nanohybrid as a ratiometric fluorescent sensor for the highly sensitive and selective detection of 4-NP. This sensor was functioned by the transfer of fluorescence resonance energy between photoluminescent carbon dots (CDs) and 4-NP. This sensor was synthesized by linking organosilane-functionalized CDs to silica-coated CdSe quantum dots (CdSe@SiO2) via Si-O bonds. The nanohybrids were further modified by anchoring a molecularly imprinted polymer (MIP) layer on the ratiometric fluorescent sensor through a facile sol-gel polymerization method. The morphology, chemical structure, and optical properties of the resulting molecularly imprinted dual-emission fluorescent probe were characterized by transmission electron microscopy and spectroscopic analysis. The probe was then applied in the detection of 4-NP and exhibited good linearity between 0.051 and 13.7 μg/mL, in addition to a low detection limit of 0.026 μg/mL. Furthermore, the simplicity, reliability, high selectivity, and high sensitivity of the developed sensor demonstrate that the combination of MIPs and ratiometric fluorescence allows the preparation of excellent fluorescent sensors for the detection of trace or ultra-trace analytes.

Stacked color image sensor using wavelength-selective organic photoconductive films with zinc-oxide thin film transistors as a signal readout circuit

NASA Astrophysics Data System (ADS)

Seo, Hokuto; Aihara, Satoshi; Namba, Masakazu; Watabe, Toshihisa; Ohtake, Hiroshi; Kubota, Misao; Egami, Norifumi; Hiramatsu, Takahiro; Matsuda, Tokiyoshi; Furuta, Mamoru; Nitta, Hiroshi; Hirao, Takashi

2010-01-01

Our group has been developing a new type of image sensor overlaid with three organic photoconductive films, which are individually sensitive to only one of the primary color components (blue (B), green (G), or red (R) light), with the aim of developing a compact, high resolution color camera without any color separation optical systems. In this paper, we firstly revealed the unique characteristics of organic photoconductive films. Only choosing organic materials can tune the photoconductive properties of the film, especially excellent wavelength selectivities which are good enough to divide the incident light into three primary colors. Color separation with vertically stacked organic films was also shown. In addition, the high-resolution of organic photoconductive films sufficient for high-definition television (HDTV) was confirmed in a shooting experiment using a camera tube. Secondly, as a step toward our goal, we fabricated a stacked organic image sensor with G- and R-sensitive organic photoconductive films, each of which had a zinc oxide (ZnO) thin film transistor (TFT) readout circuit, and demonstrated image pickup at a TV frame rate. A color image with a resolution corresponding to the pixel number of the ZnO TFT readout circuit was obtained from the stacked image sensor. These results show the potential for the development of high-resolution prism-less color cameras with stacked organic photoconductive films.

Reversibly extracellular pH controlled cellular uptake and photothermal therapy by PEGylated mixed-charge gold nanostars.

PubMed

Wang, Shouju; Teng, Zhaogang; Huang, Peng; Liu, Dingbin; Liu, Ying; Tian, Ying; Sun, Jing; Li, Yanjun; Ju, Huangxian; Chen, Xiaoyuan; Lu, Guangming

2015-04-17

Shielding nanoparticles from nonspecific interactions with normal cells/tissues before they reach and after they leave tumors is crucial for the selective delivery of NPs into tumor cells. By utilizing the reversible protonation of weak electrolytic groups to pH changes, long-chain amine/carboxyl-terminated polyethylene glycol (PEG) decorated gold nanostars (GNSs) are designed, exhibiting reversible, significant, and sensitive response in cell affinity and therapeutic efficacy to the extracellular pH (pHe) gradient between normal tissues and tumors. This smart nanosystem shows good dispersity and unimpaired photothermal efficacy in complex bioenvironment at pH 6.4 and 7.4 even when their surface charge is neutral. One PEGylated mixed-charge GNSs with certain surface composition, GNS-N/C 4, exhibits high cell affinity and therapeutic efficacy at pH 6.4, and low affinity and almost "zero" damage to cells at pH 7.4. Remarkably, this significant and sensitive response in cell affinity and therapeutic efficacy is reversible as local pH alternated. In vivo, GNS-N/C 4 shows higher accumulation in tumors and improved photothermal therapeutic efficacy than pH-insensitive GNSs. This newly developed smart nanosystem, whose cell affinity reversibly transforms in response to pHe gradient with unimpaired biostability, provides a novel effective means of tumor-selective therapy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A linear method for the retrieval of sun-induced chlorophyll fluorescence from GOME-2 and SCIAMACHY data

NASA Astrophysics Data System (ADS)

Köhler, P.; Guanter, L.; Joiner, J.

2015-06-01

Global retrievals of near-infrared sun-induced chlorophyll fluorescence (SIF) have been achieved in the last few years by means of a number of space-borne atmospheric spectrometers. Here, we present a new retrieval method for medium spectral resolution instruments such as the Global Ozone Monitoring Experiment-2 (GOME-2) and the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY). Building upon the previous work by Guanter et al. (2013) and Joiner et al. (2013), our approach provides a solution for the selection of the number of free parameters. In particular, a backward elimination algorithm is applied to optimize the number of coefficients to fit, which reduces also the retrieval noise and selects the number of state vector elements automatically. A sensitivity analysis with simulated spectra has been utilized to evaluate the performance of our retrieval approach. The method has also been applied to estimate SIF at 740 nm from real spectra from GOME-2 and for the first time, from SCIAMACHY. We find a good correspondence of the absolute SIF values and the spatial patterns from the two sensors, which suggests the robustness of the proposed retrieval method. In addition, we compare our results to existing SIF data sets, examine uncertainties and use our GOME-2 retrievals to show empirically the relatively low sensitivity of the SIF retrieval to cloud contamination.

A linear method for the retrieval of sun-induced chlorophyll fluorescence from GOME-2 and SCIAMACHY data

NASA Astrophysics Data System (ADS)

Köhler, P.; Guanter, L.; Joiner, J.

2014-12-01

Global retrievals of near-infrared sun-induced chlorophyll fluorescence (SIF) have been achieved in the last years by means of a number of space-borne atmospheric spectrometers. Here, we present a new retrieval method for medium spectral resolution instruments such as the Global Ozone Monitoring Experiment (GOME-2) and the SCanning Imaging Absorption SpectroMeter for Atmospheric ChartographY (SCIAMACHY). Building upon the previous work by Joiner et al. (2013), our approach solves existing issues in the retrieval such as the non-linearity of the forward model and the arbitrary selection of the number of free parameters. In particular, we use a backward elimination algorithm to optimize the number of coefficients to fit, which reduces also the retrieval noise and selects the number of state vector elements automatically. A sensitivity analysis with simulated spectra has been utilized to evaluate the performance of our retrieval approach. The method has also been applied to estimate SIF from real spectra from GOME-2 and for the first time, from SCIAMACHY. We find a good correspondence of the absolute SIF values and the spatial patterns from the two sensors, which suggests the robustness of the proposed retrieval method. In addition, we examine uncertainties and use our GOME-2 retrievals to show empirically the low sensitivity of the SIF retrieval to cloud contamination.

A highly selective and sensitive nanosensor for the detection of glyphosate.

PubMed

Chang, Ya-Chu; Lin, Yu-Syuan; Xiao, Guan-Ting; Chiu, Tai-Chia; Hu, Cho-Chun

2016-12-01

A turn-off fluorescence sensor synthesized by combining copper (II) oxide and multiwall carbon nanotubes (MWCNTs) were used for measuring glyphosate based on the inhibiting the catalytic activity of the CuO/MWCNTs. This sensor was synthesized by precipitating copper ions onto the acidic MWCNTs under basic conditions; the resulting material was characterized by the transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to confirm its structure. The CuO/MWCNTs nanomaterial was found to exhibit high peroxidase-like catalytic activity toward the reduction of H 2 O 2 to H 2 O and the oxidation of Amplex Red to resorufin, with a corresponding color change from pink to red and the fluorescence enhancement. However, this activity was inhibited and the fluorescence diminished when glyphosate was added to the system. Using this strategy, we applied this sensor to detect glyphosate. The results indicated that this sensor is not only highly sensitive, with a detection limit of 0.67 ppb and a linear range from 0.002 to 0.01ppm, but also exhibits good selectivity for glyphosate. When this sensor was assessed for detecting glyphosate in real water samples, recoveries of 96-107% were attained. This proposed material and method are a promising approach for rapid screening of glyphosate. Copyright © 2016 Elsevier B.V. All rights reserved.

Luminol functionalized gold nanoparticles as colorimetric and chemiluminescent probes for visual, label free, highly sensitive and selective detection of minocycline

NASA Astrophysics Data System (ADS)

He, Yi; Peng, Rufang

2014-11-01

In this work, luminol functionalized gold nanoparticles (LuAuNPs) were used as colorimetric and chemiluminescent probes for visual, label free, sensitive and selective detection of minocycline (MC). The LuAuNPs were prepared by simple one-pot reduction of HAuCl4 with luminol, which exhibited a good chemiluminescence (CL) activity owing to the presence of luminol molecules on their surface and surface plasmon resonance absorption. In the absence of MC, the color of LuAuNPs was wine red and their size was relatively small (˜25 nm), which could react with silver nitrate, producing a strong CL emission. Upon the addition of MC at acidic buffer solutions, the electrostatic interaction between positively charged MC and negatively charged LuAuNPs caused the aggregation of LuAuNPs, generating a purple or blue color. Simultaneously, the aggregated LuAuNPs did not effectively react with silver nitrate, producing a weak CL emission. The signal change was linearly dependent on the logarithm of MC concentration in the range from 30 ng to 1.0 μg for colorimetric detection and from 10 ng to 1.0 μg for CL detection. With colorimetry, a detection limit of 22 ng was achieved, while the detection limit for CL detection modality was 9.7 ng.

Dynamic response of active twist rotor blades

NASA Astrophysics Data System (ADS)

Cesnik, Carlos E. S.; Shin, Sang Joon; Wilbur, Matthew L.

2001-02-01

Dynamic characteristics of active twist rotor (ATR) blades are investigated analytically and experimentally in this paper. The ATR system is intended for vibration and potentially for noise reductions in helicopters through individual blade control. An aeroelastic model is developed to identify frequency response characteristics of the ATR blade with integral, generally anisotropic, strain actuators embedded in its composite construction. An ATR prototype blade was designed and manufactured to experimentally study the vibration reduction capabilities of such systems. Several bench and hover tests were conducted and those results are presented and discussed here. Selected results on sensitivity of the ATR system to collective setting (i.e. blade loading), blade rpm (i.e. centrifugal force and blade station velocity), and media density (i.e. altitude) are presented. They indicated that the twist actuation authority of the ATR blade is independent of the collective setting up to approximately 10P, and dependent on rotational speed and altitude near the torsional resonance frequency due to its dependency on the aerodynamic damping. The proposed model captures very well the physics and sensitivities to selected test parameters of the ATR system. The numerical result of the blade torsional loads show an average error of 20% in magnitude and virtually no difference in phase for the blade frequency response. Overall, the active blade model is in very good agreement with the experiments and can be used to analyze and design future active helicopter blade systems.

Digital tomosynthesis in breast cancer: A systematic review.

PubMed

García-León, F J; Llanos-Méndez, A; Isabel-Gómez, R

2015-01-01

To estimate and compare the diagnostic validity of tomosynthesis and digital mammography for screening and diagnosing breast cancer. We systematically searched MedLine, EMBASE, and Web of Science for the terms breast cancer, screening, tomosynthesis, mammography, sensitivity, and specificity in publications in the period comprising June 2010 through February 2013. We included studies on diagnostic tests and systematic reviews. Two reviewers selected and evaluated the articles. We used QUADAS 2 to evaluate the risk of bias and the NICE criteria to determine the level of evidence. We compiled a narrative synthesis. Of the 151 original studies identified, we selected 11 that included a total of 2475 women. The overall quality was low, with a risk of bias and follow-up and limitations regarding the applicability of the results. The level of evidence was not greater than level II. The sensitivity of tomosynthesis ranged from 69% to 100% and the specificity ranged from 54% to 100%. The negative likelihood ratio was good, and this makes tomosynthesis useful as a test to confirm a diagnosis. One-view tomosynthesis was no better than two-view digital mammography, and the evidence for the superiority of two-view tomosynthesis was inconclusive. The results for the diagnostic validity of tomosynthesis in the diagnosis of breast cancer were inconclusive and there were no results for its use in screening. Copyright © 2014 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

THE INTRACELLULAR SITE OF SYNTHESIS OF MITOCHONDRIAL RIBOSOMAL PROTEINS IN NEUROSPORA CRASSA

PubMed Central

Lizardi, Paul M.; Luck, David J. L.

1972-01-01

The intracellular site of synthesis of mitochondrial ribosomal proteins (MRP) in Neurospora crassa has been investigated using three complementary approaches. (a) Mitochondrial protein synthesis in vitro: Tritium-labeled proteins made by isolated mitochondria were compared to 14C-labeled marker MRP by cofractionation in a two-step procedure involving isoelectric focusing and polyacrylamide gel electrophoresis. Examination of the electrophoretic profiles showed that essentially none of the peaks of in vitro product corresponded exactly to any of the MRP marker peaks. (b) Sensitivity of in vivo MRP synthesis to chloramphenicol: Cells were labeled with leucine-3H in the presence of chloramphenicol, mitochondrial ribosomal subunits were subsequently isolated, and their proteins fractionated by isoelectric focusing followed by gel electrophoresis. The labeling of every single MRP was found to be insensitive to chloramphenicol, a selective inhibitor of mitochondrial protein synthesis. (c) Sensitivity of in vivo MRP synthesis to anisomycin: We have found this antibiotic to be a good selective inhibitor of cytoplasmic protein synthesis in Neurospora. In the presence of anisomycin the labeling of virtually all MRP is inhibited to the same extent as the labeling of cytoplasmic ribosomal proteins. On the basis of these three types of studies we conclude that most if not all 53 structural proteins of mitochondrial ribosomal subunits in Neurospora are synthesized by cytoplasmic ribosomes. PMID:4261038

Fast PSP measurements of wall-pressure fluctuation in low-speed flows: improvements using proper orthogonal decomposition

NASA Astrophysics Data System (ADS)

Peng, Di; Wang, Shaofei; Liu, Yingzheng

2016-04-01

Fast pressure-sensitive paint (PSP) is very useful in flow diagnostics due to its fast response and high spatial resolution, but its applications in low-speed flows are usually challenging due to limitations of paint's pressure sensitivity and the capability of high-speed imagers. The poor signal-to-noise ratio in low-speed cases makes it very difficult to extract useful information from the PSP data. In this study, unsteady PSP measurements were made on a flat plate behind a cylinder in a low-speed wind tunnel (flow speed from 10 to 17 m/s). Pressure fluctuations (Δ P) on the plate caused by vortex-plate interaction were recorded continuously by fast PSP (using a high-speed camera) and a microphone array. Power spectrum of pressure fluctuations and phase-averaged Δ P obtained from PSP and microphone were compared, showing good agreement in general. Proper orthogonal decomposition (POD) was used to reduce noise in PSP data and extract the dominant pressure features. The PSP results reconstructed from selected POD modes were then compared to the pressure data obtained simultaneously with microphone sensors. Based on the comparison of both instantaneous Δ P and root-mean-square of Δ P, it was confirmed that POD analysis could effectively remove noise while preserving the instantaneous pressure information with good fidelity, especially for flows with strong periodicity. This technique extends the application range of fast PSP and can be a powerful tool for fundamental fluid mechanics research at low speed.

Enhancement for trace analysis of sulfonamide antibiotics in water matrices using bar adsorptive microextraction (BAμE).

PubMed

Ide, A H; Ahmad, S M; Neng, N R; Nogueira, J M F

2016-09-10

In this study, the enhancement for trace analysis of sulfonamide antibiotics (sulfathiazole, sulfamethoxazole and sulfadimethoxine) and trimethoprim in water matrices is proposed using bar adsorptive microextraction combined with micro-liquid desorption followed by high-performance liquid chromatography with diode array detection (BAμE-μLD/HPLC-DAD). By comparing different polymers and activated carbons as sorbent coatings for BAμE, the polystyrene-divinylbenzene polymer (PS-DVB) showed the best selectivity for the compounds under study. Assays performed through BAμE(PS-DVB)-μLD on 25mL of ultrapure water samples spiked at the 8.0μgL(-1) level showed recoveries ranging from 63.8±1.5% to 84.2±1.9%, under optimized experimental conditions. The validated method provided satisfactory limits of detection (0.08-0.16μgL(-1)) and good linear dynamic ranges (0.16-8.00μgL(-1)) with determination coefficients higher than 0.9958. The proposed analytical methodology was applied to real matrices, such as tap, estuarine and wastewater samples using the standard addition method. It showed to be easy to implement, with good reproducibility, sensitivity and requiring small amount of sample. Furthermore, negligible consumption of organic solvents was used in compliance with the green analytical chemistry principles. When compared to other well-established microextraction approaches, BAμE demonstrated better performance concerning recovery yields and sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

Highly Sensitive and Long Term Stable Electrochemical Microelectrodes for Implantable Glucose Monitoring Devices

NASA Astrophysics Data System (ADS)

Qiang, Liangliang

A miniature wireless implantable electrochemical glucose system for continuous glucose monitoring with good selectivity, sensitivity, linearity and long term stability was developed. First, highly sensitive, long-term stable and reusable planar H2O2 microelectrodes have been fabricated by microlithography. These electrodes composed of a 300 nm Pt black layer situated on a 5 um thick Au layer, provide effective protection to the underlying chromium adhesion layer. Using repeated cyclic voltammetric sweeps in flowing buffer solution, highly sensitive Pt black working electrodes were realized with five-decade linear dynamic range and low detection limit (10 nM) for H2O2 at low oxidation potentials. Second, a highly sensitive, low cost and flexible microwire biosensor was described using 25-mum thick gold wire as working electrode together with 125-mum thick Pt/Ir and Ag wires as counter and reference electrode, embedded within a PDMS-filled polyethylene tube. Surface area and activity of sensor was enhanced by converting gold electrode to nanoporous configuration followed by electrodeposition of platinum black. Glucose oxidase based biosensors by electrodeposition of poly(o-phenylenediamine) and glucose oxidase on the working electrode, displayed a higher glucose sensitivity (1.2 mA mM-1 cm-2) than highest literature reported. In addition it exhibits wide detection range (up to 20 mM) and selectivity (>95%). Third, novel miniaturized and flexible microelectrode arrays with 8 of 25 mum electrodes displayed the much needed 3D diffusion profiles similar to a single 25 mum microelectrode, but with one order increase in current levels. These microelectrode arrays displayed a H2O2 sensitivity of 13 mA mM-1 cm-2, a wide dynamic range of 100 nM to 10 mM, limit of detection of 10 nM. These microwire based edge plane microsensors incorporated flexibility, miniaturization and low operation potential are an promising approach for continuous in vivo metabolic monitoring. Fourth, homemade miniature wireless potentisotat was fabricated based on low power consumption integrated circuits and surface mount parts. The miniature wireless potentisotat with up to two week life-time for continuous glucose sensing has a size less than 9x22x10 mm and weight ˜3.4 grams. Primary in vivo experiment showed homemade system has the exactly same respond and trend as commercial glucose meter.

Selective enrichment and separation of phosphotyrosine peptides by thermosensitive molecularly imprinted polymers.

PubMed

Yang, Xiaoqing; Xia, Yan

2016-01-01

Novel thermosensitive molecularly imprinted polymers were successfully prepared using the epitope imprinting approach in the presence of the mimic template phenylphosphonic acid, the functional monomer vinylphosphonic acid-Ti(4+) , the temperature-sensitive monomer N-isopropylacrylamide and the crosslinker N,N'-methylenebisacrylamide. The ratio of the template/thermosensitive monomers/crosslinker was optimized, and when the ratio was 2:2:1, the prepared thermosensitive molecularly imprinted polymers had the highest imprinting factor. The synthetic thermosensitive molecularly imprinted polymers were characterized by Fourier transform infrared spectroscopy to reveal the combination and elution processes of the template. Then, the adsorption capacity and thermosensitivity was measured. When the temperature was 28°C, the imprinting factor was the highest. The selectivity and adsorption capacity of the thermosensitive molecularly imprinted polymers for phosphotyrosine peptides from a mixture of three tailor-made peptides were measured by high-performance liquid chromatography. The results showed that the thermosensitive molecularly imprinted polymers have good selectivity for phosphotyrosine peptides. Finally, the imprinted hydrogels were applied to specifically adsorb phosphotyrosine peptides from a sample mixture containing phosphotyrosine and a tryptic digest of β-casein, which demonstrated high selectivity. After four rebinding cycles, 78.9% adsorption efficiency was still retained. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Neutral ligand TIPA-based two 2D metal-organic frameworks: ultrahigh selectivity of C2H2/CH4 and efficient sensing and sorption of Cr(vi ).

PubMed

Fu, Hong-Ru; Zhao, Ying; Zhou, Zhan; Yang, Xiao-Gang; Ma, Lu-Fang

2018-03-12

One neutral tripodal semi-rigidity ligand tri(4-imidazolylphenyl)amine (TIPA) with excellent hole-transfer nature, was selected as a linker to construct MOFs. Two two-dimensional (2D) microporous metal-organic frameworks (MOFs) were synthesized solvothermally: [Ni(TIPA)(COO - ) 2 (H 2 O)]·2(DMF)2(H 2 O) (1) and [Cd(TIPA) 2 (ClO 4 - ) 2 ]·(DMF)3(H 2 O) (2). Compound 1 incorporated carboxylic groups into the channel and exhibited the high capacity of light hydrocarbons as well as the remarkable selectivity of C 2 H 2 /CH 4 . The value is in excess of 100 at room temperature, which is the highest value reported to date. Compound 2, as a cationic framework with high water stability, was not only applied as a sensor, displaying the ultrahigh sensitivity against Cr 2 O 7 2- with a detection limit as low as 8 ppb, but also possessed excellent Cr(vi) sorption with good repeatability in aqueous solution. This study provides an efficient strategy to design cationic MOFs for the selective separation of light hydrocarbons and the sensing and trapping of toxic chromate for the purification of water.

Determination of urinary levels of leukotriene B(4) using ad highly specific and sensitive methodology based on automatic MEPS combined with UHPLC-PDA analysis.

PubMed

Perestrelo, Rosa; Silva, Catarina L; Câmara, José S

2015-11-01

Leukotriene B4 (LTB4) is a potent mediator of inflammation and plays a key function in the pathophysiology of chronic asthma. Detectable urinary levels of LTB4, arises from the activation of leukotriene pathways. In this study an ultra-fast, selective and sensitive analytical method based on semi-automatic microextraction by packed sorbents (MEPS) technique, using a new digitally controlled syringe (eVol®) combined with ultra-high pressure liquid chromatography (UHPLC), is proposed for the measurement of urinary LTB4 (U-LTB4) levels in a group of asthmatic patients (APs) and healthy controls (CTRL). Important parameters affecting MEPS performance, namely sorbent type, number of extraction cycles (extract-discard) and elution volume, were evaluated. The optimal experimental conditions among those investigated for the quantification of U-LTB4 in urine samples were as follows: porous graphitic carbon sorbent (PGC), 10 extractions cycle (10×250 μL of sample) and LTB4 elution with 100 μL of acetonitrile. The UHPLC optimum conditions resulted in a mobile phase consisting of 95% (v/v) of acid aqueous solution (v/v), and acetonitrile 5% (v/v); flow rate of 500 µL/min, and a column temperature of 37±0.1 °C. Under optimized conditions the proposed method exhibit good selectivity and sensitivity LOD (0.37 ng/mL) and LOQ (1.22 ng/mL). The recovery ranging from 86.4 to 101.1% for LTB4, with relative standard deviations (% RSD) no larger than 5%. In addition, the method also afforded good results in terms of linearity (r(2)>0.995) within the established concentration range, with a residual deviation for each calibration point below 6%, and intra- and inter-day repeatability in urine samples with RSD values lower than 4 and 5%, respectively. The application of the method to urine samples revealed a tendency towards the increased urinary LTB4 levels in APs (5.42±0.17 ng/mL) when compared to those of CTRL group (from ND to 1.9 ng/mL). Urinary measurement of LTB4 may be an interesting and non-invasive option to assess control of asthma. Copyright © 2015 Elsevier B.V. All rights reserved.

An application of optical coherence tomography and a smart polymer gel to construct an enzyme-free sugar sensor

NASA Astrophysics Data System (ADS)

Ouiganon, Sirirat; Thammakhet, Chongdee; Thavarungkul, Panote; Kanatharana, Proespichaya; Buranachai, Chittanon

2016-06-01

This work reports a novel enzyme-free sugar sensor development based on optical coherence tomography (OCT) and a 3-acrylamidophenylboronic acid-acrylamide copolymer gel that swells when it binds sugar molecules. Utilizing OCT to measure the gel swelling in the presence of glucose and fructose, selected as model targets, the sensor provided a linear range of 2.5-20.0 mM for glucose and 0.01-0.20 mM for fructose detections with a good sensitivity for both sugars under optimal conditions. With some further improvements, the sensor could be used in harsh conditions that are not suitable for enzyme-based sugar sensors and for highly visible light-absorbing solutions.