The Simultaneous Electrochemical Detection of Catechol and Hydroquinone with [Cu(Sal-β-Ala)(3,5-DMPz)2]/SWCNTs/GCE

PubMed Central

Alshahrani, Lina Abdullah; Li, Xi; Luo, Hui; Yang, Linlin; Wang, Mengmeng; Yan, Songling; Liu, Peng; Yang, Yuqin; Li, Quanhua

2014-01-01

A glassy carbon electrode was modified with a copper(II) complex [Cu(Sal-β-Ala) (3,5-DMPz)2] (Sal = salicylaldehyde, β-Ala = β-alanine, 3,5-DMPz = 3,5-dimethylpyrazole) and single-walled carbon nanotubes (SWCNTs). The modified electrode was used to detect catechol (CT) and hydroquinone (HQ) and exhibited good electrocatalytic activities toward the oxidation of CT and HQ. The peak currents were linear with the CT and HQ concentrations over the range of 5–215 μmol·L−1 and 5–370 μmol·L−1 with corresponding detection limits of 3.5 μmol·L−1 and 1.46 μmol·L−1 (S/N = 3) respectively. Moreover, the modified electrode exhibited good sensitivity, stability and reproducibility for the determination of CT and HQ, indicating the promising applications of the modified electrode in real sample analysis. PMID:25429411

Electrochemical immunosensor with NiAl-layered double hydroxide/graphene nanocomposites and hollow gold nanospheres double-assisted signal amplification.

PubMed

Qiao, Lu; Guo, Yemin; Sun, Xia; Jiao, Yancui; Wang, Xiangyou

2015-08-01

A sensitive electrochemical immunosensor based on NiAl-layered double hydroxide/graphene nanocomposites (NiAl-LDH/G) and hollow gold nanospheres (HGNs) was proposed for chlorpyrifos detection. The NiAl-LDH/G was prepared using a conventional coprecipitation process and reduction of the supporting graphene oxide. Subsequently, the nanocomposites were dispersed with chitosan (CS). The NiAl-LDH/G possessed good electrochemical behavior and high binding affinity to the electrode. The high surface areas of HGNs and the vast aminos and hydroxyls of CS provided a platform for the covalently crosslinking of antibody. Under optimal conditions, the immunosensor exhibited a wide linear range from 5 to 150 μg/mL and from 150 to 2 μg/mL, with a detection limit of 0.052 ng/mL. The detection results showed good agreement with standard gas chromatography method. The constructed immunosensor exhibited good reproducibility, high specificity, acceptable stability and regeneration performance, which provided a new promising tool for chlorpyrifos detection in real samples.

One-pot synthesis of zeolitic imidazolate framework-8/poly (methyl methacrylate-ethyleneglycol dimethacrylate) monolith coating for stir bar sorptive extraction of phytohormones from fruit samples followed by high performance liquid chromatography-ultraviolet detection.

PubMed

You, Linna; He, Man; Chen, Beibei; Hu, Bin

2017-11-17

In this work, zeolitic imidazolate framework-8 (ZIF-8)/poly (methyl methacrylate-ethyleneglycol dimethacrylate) (MMA-EGDMA) composite monolith was in situ synthesized on stir bar by one-pot polymerization. Compared with the neat monolith, ZIF-8/poly(MMA-EGDMA) composite monolith has larger surface area and pore volume. It also exhibits higher extraction efficiency for target phytohormones than poly(MMA-EGDMA) monolith and commercial polyethylene glycol (PEG) coated stir bar. Based on it, a method of ZIF-8/poly(MMA-EGDMA) monolith coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detection (HPLC-UV) was established for the analysis of five phytohormones in apple and pear samples. The developed method exhibited low limits of detection (0.11-0.51μg/L), wide linear range (0.5-500μg/L) and good recoveries (82.7-111%), which demonstrated good application potential of the ZIF-8/monolith coated stir bar in trace analysis of organic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of Nb Doping Concentration on Bolometric Properties of RF Magnetron Sputtered Nb:TiO2- x Films

NASA Astrophysics Data System (ADS)

Reddy, Y. Ashok Kumar; Shin, Young Bong; Kang, In-Ku; Lee, Hee Chul

2018-03-01

The present study directly addresses the improved bolometric properties by means of different Nb doping concentrations into TiO2- x films. The x-ray diffraction patterns do not display any obvious diffraction peaks, suggesting that all the films deposited at room temperature had an amorphous structure. A small binding energy shift was observed in x-ray photo electron spectroscopy due to the change of chemical composition with Nb doping concentration. All the device samples exhibit linear I- V characteristics, which attests to the formation of good ohmic contact with low contact resistance between the Nb:TiO2- x (TNO) film and the electrode (Ti) material. The performance of the bolometric material can be evaluated through the temperature coefficient of resistance (TCR), and the absolute value of TCR was found to be increased from 2.54% to 2.78% with increasing the Nb doping concentration. The voltage spectral density of 1/ f noise was measured in the frequency range of 1-60 Hz and found to be decreased with increase of Nb doping concentration. As a result, for 1 at.% Nb-doped TNO sample exhibits improved bolometric properties towards the good infrared image sensor device.

Preparation of molecular imprinted microspheres based on inorganic-organic co-functional monomer for miniaturized solid-phase extraction of fluoroquinolones in milk.

PubMed

Wang, Hui; Wang, Ruiling; Han, Yehong

2014-02-15

An inorganic-organic co-functional monomer, methacrylic acid-vinyltriethoxysilan (MAA-VTES) was designed for the synthesis of molecularly imprinted microspheres (MIMs). By virtue of the aqueous suspension polymerization and dummy template (pazufloxacin), the obtained MAA-VTES based MIMs exhibited good recognition and selectivity to fluoroquinolones (FQs), and were successfully applied as selective sorbents of a miniaturized home-made solid phase extraction device for the determination of ofloxacin (OFL), lomefloxacin (LOM) and ciprofloxacin (CIP) in milk samples. Under the optimum conditions of the miniaturized molecularly imprinted solid phase extraction (mini-MISPE) coupled with liquid chromatography-ultraviolet detector (LC-UV), good linearities were obtained for three FQs in a range of 0.2-20.0μgmL(-1) and the average recoveries at three spiked levels were ranged from 87.2% to 106.1% with the relative standard deviation (RSD) less than 5.4%. The presented co-functional monomer based mini-MISPE-LC-UV protocol introduced the rigidity and flexibility of inorganic silicon materials, exhibited excellent extraction performance towards targets, and could be potentially applied to the determination of FQs in milk samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Magnetism of californium metal

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

Nave, S.E.; Moore, J.R.; Spaar, M.T.

1984-01-01

Magnetic susceptibility measurements have been made on samples of californium-249 metal having the dhcp crystal structure. At temperatures between 100K and 300K and at fields up to 50 kilogauss, the samples exhibit Curie-Weiss behavior with 3 samples giving a magnetic moment per atom of ..mu../sub eff/ = 10.6 +- 0.2 ..mu../sub B/ and paramagnetic Weiss temperatures, theta/sub p/, in the range of -2K to -41K. These values of ..mu../sub eff/ are in good agreement with the value expected (10.62..mu../sub B/) for a free-ion 5f/sup 9/ configuration based on an L-S coupling scheme and Hund's Rule. A fourth sample gives themore » values ..mu../sub eff/ = 9.7 +- 0.2..mu../sub B/ and theta/sub p/ = -41K. At low temperatures the samples exhibit an ordered magnetic transition to a state with a saturated moment of 6.1 ..mu../sub B//atom when extrapolated to infinitely-high field. The low temperature ordered phase exists at temperatures below T/sub c/ = 51 +- 2K as determined from constant magnetization plots. 2 references, 3 figures.« less

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

Chen, Zhe; Cao, Minhua, E-mail: caomh@bit.edu.cn; Key Laboratory of Cluster Science, Ministry of Education of China, Department of Chemistry, Beijing Institute of Technology, Beijing 100081

Research highlights: {yields} Novel Bi{sub 2}S{sub 3} hierarchical nanostructures self-assembled by nanorods are successfully synthesized in mild benzyl alcohol system under hydrothermal conditions. {yields} The hierarchical nanostructures exhibit a flower-like shape. {yields} PVP plays an important role for the formation of the hierarchical nanostructures. {yields} Bi{sub 2}S{sub 3} film prepared from the flower-like hierarchical nanostructures exhibits good hydrophobic properties. -- Abstract: Novel Bi{sub 2}S{sub 3} hierarchical nanostructures self-assembled by nanorods are successfully synthesized in mild benzyl alcohol system under hydrothermal conditions. The hierarchical nanostructures exhibit a flower-like shape. X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), transmissionmore » electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED) were used to characterize the as-synthesized samples. Meanwhile, the effect of various experimental parameters including the concentration of reagents and reaction time on final product has been investigated. In our experiment, PVP plays an important role for the formation of the hierarchical nanostructures and the possible mechanism was proposed. In addition, Bi{sub 2}S{sub 3} film prepared from the flower-like hierarchical nanostructures exhibits good hydrophobic properties, which may bring nontrivial functionalities and may have some promising applications in the future.« less

Co-immobilization of glucoamylase and glucose oxidase for electrochemical sequential enzyme electrode for starch biosensor and biofuel cell.

PubMed

Lang, Qiaolin; Yin, Long; Shi, Jianguo; Li, Liang; Xia, Lin; Liu, Aihua

2014-01-15

A novel electrochemical sequential biosensor was constructed by co-immobilizing glucoamylase (GA) and glucose oxidase (GOD) on the multi-walled carbon nanotubes (MWNTs)-modified glassy carbon electrode (GCE) by chemical crosslinking method, where glutaraldehyde and bovine serum albumin was used as crosslinking and blocking agent, respectively. The proposed biosensor (GA/GOD/MWNTs/GCE) is capable of determining starch without using extra sensors such as Clark-type oxygen sensor or H2O2 sensor. The current linearly decreased with the increasing concentration of starch ranging from 0.005% to 0.7% (w/w) with the limit of detection of 0.003% (w/w) starch. The as-fabricated sequential biosensor can be applicable to the detection of the content of starch in real samples, which are in good accordance with traditional Fehling's titration. Finally, a stable starch/O2 biofuel cell was assembled using the GA/GOD/MWNTs/GCE as bioanode and laccase/MWNTs/GCE as biocathode, which exhibited open circuit voltage of ca. 0.53 V and the maximum power density of 8.15 μW cm(-2) at 0.31 V, comparable with the other glucose/O2 based biofuel cells reported recently. Therefore, the proposed biosensor exhibited attractive features such as good stability in weak acidic buffer, good operational stability, wide linear range and capable of determination of starch in real samples as well as optimal bioanode for the biofuel cell. Copyright © 2013 Elsevier B.V. All rights reserved.

Hydraulic and acoustic properties of the active Alpine Fault, New Zealand: Laboratory measurements on DFDP-1 drill core

NASA Astrophysics Data System (ADS)

Carpenter, B. M.; Kitajima, H.; Sutherland, R.; Townend, J.; Toy, V. G.; Saffer, D. M.

2014-03-01

We report on laboratory measurements of permeability and elastic wavespeed for a suite of samples obtained by drilling across the active Alpine Fault on the South Island of New Zealand, as part of the first phase of the Deep Fault Drilling Project (DFDP-1). We find that clay-rich cataclasite and principal slip zone (PSZ) samples exhibit low permeabilities (⩽10-18 m), and that the permeability of hanging-wall cataclasites increases (from c. 10-18 m to 10-15 m) with distance from the fault. Additionally, the PSZ exhibits a markedly lower P-wave velocity and Young's modulus relative to the wall rocks. Our laboratory data are in good agreement with in situ wireline logging measurements and are consistent with the identification of an alteration zone surrounding the PSZ defined by observations of core samples. The properties of this zone and the low permeability of the PSZ likely govern transient hydrologic processes during earthquake slip, including thermal pressurization and dilatancy strengthening.

Comparative evaluation of the COBAS AmpliPrep/COBAS TaqMan HIV type 1 test (CAP/CTM) and VERSANT HIV type 1 RNA 3.0 assay (bDNA) for quantifying HIV type 1 viral loads in China.

PubMed

Xu, Sihong; Song, Aijing; Nie, Jianhui; Li, Xiuhua; Li, Jingyun; Bao, Zuoyi; Wang, Youchun

2008-11-01

In the present study, 277 clinical samples from untreated and treated HIV-1-infected patients with different clades were used to assess the agreement between the COBAS AmpliPrep/COBAS TaqMan HIV-1 test (CAP/CTM) and VERSANT HIV-1 RNA 3.0 Assay (bDNA). A qualitative comparison of the results of the two assays showed concordance for 255 positive and 15 negative samples (94.95%, kappa = 0.798). However, seven samples with viral loads close to the lower limit of detection for CAP/CTM were negative by bDNA. A significant correlation (r = 0.881, p < 0.001) was observed for 253 samples with viral loads within the dynamic ranges of the two assays, and Bland-Altman analysis showed good agreement (96.05%) between the two assays for these 253 samples [mean (+/-2 SD), 0.389(-0.385, 1.163)]. Furthermore, ART drugs had no impact on the performances of the two assays. For samples with different clades predominant in China, the fitted regression line differed significantly from the line of equality, although significant correlations (r = 0.850-0.891, p < 0.001) and good agreements (92.86-97.25%) were found for the two assays. The mean differences for clade B' and BC samples were significant (p < 0.01). Good precision for clade B' samples was achieved for the CAP/CTM (CV: 20.73%) and bDNA (CV: 12.19%) assays. Furthermore, for clades B', BC, and AE, both assays exhibited good linearities (r = 0.9773-0.9998). Thus, the CAP/CTM and bDNA assays could be useful for quantifying HIV-1 RNA in routine clinical samples and monitoring viral loads in treated and untreated HIV-infected patients in China.

Microstructures and Mechanical Properties of Commercially Pure Ti Processed by Rotationally Accelerated Shot Peening

PubMed Central

Huang, Zhaowen; Cao, Yang; Nie, Jinfeng; Zhou, Hao; Li, Yusheng

2018-01-01

Gradient structured materials possess good combinations of strength and ductility, rendering the materials attractive in industrial applications. In this research, a surface nanocrystallization (SNC) technique, rotationally accelerated shot peening (RASP), was employed to produce a gradient nanostructured pure Ti with a deformation layer that had a thickness of 2000 μm, which is thicker than those processed by conventional SNC techniques. It is possible to fabricate a gradient structured Ti workpiece without delamination. Moreover, based on the microstructural features, the microstructure of the processed sample can be classified into three regions, from the center to the surface of the RASP-processed sample: (1) a twinning-dominated core region; (2) a “twin intersection”-dominated twin transition region; and (3) the nanostructured region, featuring nanograins. A microhardness gradient was detected from the RASP-processed Ti. The surface hardness was more than twice that of the annealed Ti sample. The RASP-processed Ti sample exhibited a good combination of yield strength and uniform elongation, which may be attributed to the high density of deformation twins and a strong back stress effect. PMID:29498631

Rapid Determination of the Chemical Oxygen Demand of Water Using a Thermal Biosensor

PubMed Central

Yao, Na; Wang, Jinqi; Zhou, Yikai

2014-01-01

In this paper we describe a thermal biosensor with a flow injection analysis system for the determination of the chemical oxygen demand (COD) of water samples. Glucose solutions of different concentrations and actual water samples were tested, and their COD values were determined by measuring the heat generated when the samples passed through a column containing periodic acid. The biosensor exhibited a large linear range (5 to 3000 mg/L) and a low detection limit (1.84 mg/L). It could tolerate the presence of chloride ions in concentrations of 0.015 M without requiring a masking agent. The sensor was successfully used for detecting the COD values of actual samples. The COD values of water samples from various sources were correlated with those obtained by the standard dichromate method; the linear regression coefficient was found to be 0.996. The sensor is environmentally friendly, economical, and highly stable, and exhibits good reproducibility and accuracy. In addition, its response time is short, and there is no danger of hazardous emissions or external contamination. Finally, the samples to be tested do not have to be pretreated. These results suggest that the biosensor is suitable for the continuous monitoring of the COD values of actual wastewater samples. PMID:24915178

Preliminary validation of the Yale Food Addiction Scale.

PubMed

Gearhardt, Ashley N; Corbin, William R; Brownell, Kelly D

2009-04-01

Previous research has found similarities between addiction to psychoactive substances and excessive food consumption. Further exploration is needed to evaluate the concept of "food addiction," as there is currently a lack of psychometrically validated measurement tools in this area. The current study represents a preliminary exploration of the Yale Food Addiction Scale (YFAS), designed to identify those exhibiting signs of addiction towards certain types of foods (e.g., high fat and high sugar). Survey data were collected from 353 respondents from a stratified random sample of young adults. In addition to the YFAS, the survey assessed eating pathology, alcohol consumption and other health behaviors. The YFAS exhibited adequate internal reliability, and showed good convergent validity with measures of similar constructs and good discriminant validity relative to related but dissimilar constructs. Additionally, the YFAS predicted binge-eating behavior above and beyond existing measures of eating pathology, demonstrating incremental validity. The YFAS is a sound tool for identifying eating patterns that are similar to behaviors seen in classic areas of addiction. Further evaluation of the scale is needed, especially due to a low response rate of 24.5% and a non-clinical sample, but confirmation of the reliability and validity of the scale has the potential to facilitate empirical research on the concept of "food addiction".

Assembly and evaluation of a pyroelectric detector bonded to vertically aligned multiwalled carbon nanotubes over thin silicon.

PubMed

Theocharous, E; Theocharous, S P; Lehman, J H

2013-11-20

A novel pyroelectric detector consisting of a vertically aligned nanotube array on thin silicon (VANTA/Si) bonded to a 60 μm thick crystal of LiTaO₃ has been fabricated. The performance of the VANTA/Si-coated pyroelectric detector was evaluated using National Physical Laboratory's (NPL's) detector-characterization facilities. The relative spectral responsivity of the detector was found to be spectrally flat in the 0.8-24 μm wavelength range, in agreement with directional-hemispherical reflectance measurements of witness samples of the VANTA. The spatial uniformity of response of the test detector exhibited good uniformity, although the nonuniformity increased with increasing modulation frequency. The nonuniformity may be assigned either to the dimensions of the VANTA or the continuity of the bond between the VANTA/Si coating and the pyroelectric crystal substrate. The test detector exhibited a small superlinear response, which is similar to that of pyroelectric detectors coated with good quality gold-black coatings.

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.

Characterizations and Electrical Modelling of Sensory Samples Formed from Synthesized Vanadium (V) Oxide and Copper Oxide Graphene Quantum Tunneling Composites (GQTC) Applied in Electrotribology

PubMed Central

Habdank-Wojewódzki, Tadeusz; Habdank, Josef; Cwik, Przemyslaw; Zimowski, Slawomir

2016-01-01

CuO and V2O5 graphene quantum tunneling composites (GQTC) presented in this article were produced and their sensory properties were analyzed. The composites were synthesised using two stage high-power milling process, which resulted in materials that have good temeprature and pressure sensory properties. Described production process defines internal structure of materials such that when used as sensor in the desired range, it exhibits a strong percolation effect. The experiment, with controlled changing physical conditions during electrotribological measurement, enabled analyzing of the composites’ conductivity as a function of the sensory properties: applied temperature, pressure, tangential force and wear. The sensory characteristic was successfully modelled by invertible generalized equations, and used to create sensor capable of estimating temperature or pressure in the real time. The developed materials have the potential to be applied in the areas where miniaturization is essential, due to the materials exhibiting good sensory properties in mini and micro scale. PMID:26742044

Characterizations and Electrical Modelling of Sensory Samples Formed from Synthesized Vanadium (V) Oxide and Copper Oxide Graphene Quantum Tunneling Composites (GQTC) Applied in Electrotribology.

PubMed

Habdank-Wojewódzki, Tadeusz; Habdank, Josef; Cwik, Przemyslaw; Zimowski, Slawomir

2016-01-05

CuO and V₂O₅ graphene quantum tunneling composites (GQTC) presented in this article were produced and their sensory properties were analyzed. The composites were synthesised using two stage high-power milling process, which resulted in materials that have good temeprature and pressure sensory properties. Described production process defines internal structure of materials such that when used as sensor in the desired range, it exhibits a strong percolation effect. The experiment, with controlled changing physical conditions during electrotribological measurement, enabled analyzing of the composites' conductivity as a function of the sensory properties: applied temperature, pressure, tangential force and wear. The sensory characteristic was successfully modelled by invertible generalized equations, and used to create sensor capable of estimating temperature or pressure in the real time. The developed materials have the potential to be applied in the areas where miniaturization is essential, due to the materials exhibiting good sensory properties in mini and micro scale.

Characteristics and Corrosion Behavior of Pure Titanium Subjected to Surface Mechanical Attrition

NASA Astrophysics Data System (ADS)

Fu, Tianlin; Wang, Xiao; Liu, Jianxiong; Li, Li; Yu, Xiaohua; Zhan, Zhaolin

2017-10-01

A stable passive film exhibiting good corrosion resistance in a 3.5 wt.% NaCl solution was formed on the surface of pure titanium (Ti) subjected to a surface mechanical attrition treatment (SMAT). The corrosion potential (-0.21 V) of the film was significantly higher than that (-0.92 V) of the untreated sample. Moreover, the corrosion current density was an order of magnitude lower than that of the untreated sample. SMAT resulted in a decrease in the vacancy condensation in the TiO2 film, thereby inhibiting the invasion and diffusion of Cl- in the film.

Novel ion imprinted magnetic mesoporous silica for selective magnetic solid phase extraction of trace Cd followed by graphite furnace atomic absorption spectrometry detection

NASA Astrophysics Data System (ADS)

Zhao, Bingshan; He, Man; Chen, Beibei; Hu, Bin

2015-05-01

Determination of trace Cd in environmental, biological and food samples is of great significance to toxicological research and environmental pollution monitoring. While the direct determination of Cd in real-world samples is difficult due to its low concentration and the complex matrix. Herein, a novel Cd(II)-ion imprinted magnetic mesoporous silica (Cd(II)-II-MMS) was prepared and was employed as a selective magnetic solid-phase extraction (MSPE) material for extraction of trace Cd in real-world samples followed by graphite furnace atomic absorption spectrometry (GFAAS) detection. Under the optimized conditions, the detection limit of the proposed method was 6.1 ng L- 1 for Cd with the relative standard deviation (RSD) of 4.0% (c = 50 ng L- 1, n = 7), and the enrichment factor was 50-fold. To validate the proposed method, Certified Reference Materials of GSBZ 50009-88 environmental water, ZK018-1 lyophilized human urine and NIES10-b rice flour were analyzed and the determined values were in a good agreement with the certified values. The proposed method exhibited a robust anti-interference ability due to the good selectivity of Cd(II)-II-MMS toward Cd(II). It was successfully employed for the determination of trace Cd(II) in environmental water, human urine and rice samples with recoveries of 89.3-116%, demonstrating that the proposed method has good application potential in real world samples with complex matrix.

Synthesis of Reduced Graphene Oxide-Modified LiMn0.75Fe0.25PO4 Microspheres by Salt-Assisted Spray Drying for High-Performance Lithium-Ion Batteries

PubMed Central

Kim, Myeong-Seong; Kim, Hyun-Kyung; Lee, Suk-Woo; Kim, Dong-Hyun; Ruan, Dianbo; Chung, Kyung Yoon; Lee, Sang Hyun; Roh, Kwang Chul; Kim, Kwang-Bum

2016-01-01

Microsized, spherical, three-dimensional (3D) graphene-based composites as electrode materials exhibit improved tap density and electrochemical properties. In this study, we report 3D LiMn0.75Fe0.25PO4/reduced graphene oxide microspheres synthesized by one-step salt-assisted spray drying using a mixed solution containing a precursor salt and graphene oxide and a subsequent heat treatment. During this process, it was found that the type of metal salt used has significant effects on the morphology, phase purity, and electrochemical properties of the synthesized samples. Furthermore, the amount of the chelating agent used also affects the phase purity and electrochemical properties of the samples. The composite exhibited a high tap density (1.1 g cm−3) as well as a gravimetric capacity of 161 mA h g−1 and volumetric capacity of 281 mA h cm−3 at 0.05 C-rate. It also exhibited excellent rate capability, delivering a discharge capacity of 90 mA h g−1 at 60 C-rate. Furthermore, the microspheres exhibited high energy efficiency and good cyclability, showing a capacity retention rate of 93% after 1000 cycles at 10 C-rate. PMID:27220812

The performance of hematite nanostructures in different humidity levels

NASA Astrophysics Data System (ADS)

Ahmad, W. R. W.; Mamat, M. H.; Zoolfakar, A. S.; Khusaimi, Z.; Yusof, M. M.; Ismail, A. S.; Saidi, S. A.; Rusop, M.

2018-05-01

In this study, hematite (α-Fe2O3) nanostructure were prepared in Schott vials on fluorine-doped tin oxide (FTO) coated glass substrate using the sonicated immersion method in aqueous solution with ferric chloride FeCl3ṡ6H2O as a precursor and urea NH2-CONH2 as a stabilizer. The samples were characterized for different level of humidity conditions within range 40% to 90% RH. Based on the results obtained, the hematite nanostructure exhibited good optical properties and virtuous sensor response with high sensitivity. The fabricated hematite nanostructure has revealed a good potential for humidity sensor application based on the results obtained under different levels of humidity.

High-Temperature Thermoelectric Properties of Perovskite-Type Pr0.9Sr0.1Mn1- x Fe x O3 (0 ≤ x ≤ 1)

NASA Astrophysics Data System (ADS)

Nakatsugawa, H.; Saito, M.; Okamoto, Y.

2017-05-01

Polycrystalline samples of Pr0.9Sr0.1Mn1- x Fe x O3 (0 ≤ x ≤ 1) have been synthesized using a conventional solid-state reaction method, and the crystal structure studied at room temperature. The magnetic susceptibility was measured from 5 K to 350 K. The electrical resistivity, Seebeck coefficient, and thermal conductivity were investigated as functions of temperature below 850 K. For all samples, the perovskite structure at room temperature exhibited orthorhombic Pbnm phase. While the Pr0.9Sr0.1MnO3 ( x = 0) sample exhibited ferromagnetic-like ground state below T C = 145 K (Curie temperature), the ferromagnetic transition temperature T C decreased with increasing x. The Seebeck coefficient of the samples with 0 ≤ x ≤ 0.8 decreased with increasing temperature because of double-exchange interaction of Mn ions. In fact, the carrier type for x = 0 changed from hole-like to electron-like behavior above 800 K. On the other hand, the samples with x ≥ 0.9 showed large positive Seebeck coefficient over the entire temperature range, indicating that the low-spin state of Fe ions dominated the electronic structure for this x range. In particular, the sample with x = 1 exhibited p-type thermoelectric properties with relatively high Seebeck coefficient, moderate electrical resistivity, and low thermal conductivity. Thus, the sample with x = 1 showed power factor of 20 μW m-1 K-2 at 850 K leading to ZT of 0.024 at this temperature, indicating that hole-doped perovskite-type iron oxide is a good candidate high-temperature thermoelectric p-type oxide.

Polymer monolithic capillary microextraction on-line coupled with inductively coupled plasma-mass spectrometry for the determination of trace Au and Pd in biological samples

NASA Astrophysics Data System (ADS)

Liu, Xiaolan; He, Man; Chen, Beibei; Hu, Bin

2014-11-01

A novel method based on on-line polymer monolithic capillary microextraction (CME)-inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of trace Au and Pd in biological samples. For this purpose, poly(glycidyl methacrylate-ethylene dimethacrylate) monolith was prepared and functionalized with mercapto groups. The prepared monolith exhibited good selectivity to Au and Pd, and good resistance to strong acid with a long life span. Factors affecting the extraction efficiency of CME, such as sample acidity, sample flow rate, eluent conditions and coexisting ion interference were investigated in detail. Under the optimal conditions, the limits of detection (LODs, 3σ) were 5.9 ng L- 1 for Au and 8.3 ng L- 1 for Pd, and the relative standard deviations (RSDs, c = 50 ng L-1, n = 7) were 6.5% for Au and 1.1% for Pd, respectively. The developed method was successfully applied to the determination of Au and Pd in human urine and serum samples with the recovery in the range of 84-118% for spiked samples. The developed on-line polymer monolithic CME-ICP-MS method has the advantages of rapidity, simplicity, low sample/reagent consumption, high sensitivity and is suitable for the determination of trace Au and Pd in biological samples with limited amount available and complex matrix.

Study on photophysical and aggregation induced emission recognition of 1,8-naphthalimide probe for casein by spectroscopic method

NASA Astrophysics Data System (ADS)

Sun, Yang; Liu, Zhen; Liang, Xuhua; Fan, Jun; Han, Quan

2013-05-01

A novel water-soluble 1,8-naphthalimide derivative 1, bearing two acetic carboxylic groups, exhibited fluorescent turn-on recognition for casein based on the aggregation induced emission (AIE) character. The photophysical properties of 1 consisting of donor and acceptor units were investigated in different solutions. The fluorescence intensity decreased through taking advantage of twisted intramolecular charge transfer (TICT) and self-association emission with increasing solvent polarity. Moreover, the spectral red-shift and intensity quench in protic solvents were caused by the excited-state hydrogen bond strengthening effect. Density Functional Theory (DFT) calculations revealed that 1 exhibited a strong TICT character. The AIE mechanism of 1 with casein was due to 1 docked in the hydrophobic cavity between sub-micelles and bound with Tyr and Trp residues, resulting in the aggregation of 1 on the casein surface and emission enhancement. Based on this, a novel casein assay method was developed. The proposed exhibited a good linear range from 0.1 to 22 μg mL-1, with the detection limit of 2.8 ng mL-1. Satisfactory reproducibility, reversibility and a short response time were realized. This method was applied to the determination of casein in milk powder samples and the results were in good agreement with the result of Biuret method.

In vitro physicochemical, phytochemical and functional properties of fiber rich fractions derived from by-products of six fruits.

PubMed

Saikia, Sangeeta; Mahanta, Charu Lata

2016-03-01

A comparative study was done on the health promoting and functional properties of the fibers obtained as by-products from six fruits viz., pomace of carambola (Averrhoa carambola L.) and pineapple (Ananas comosus L. Merr), peels of watermelon (Citrullus lanatus), Burmese grape (Baccurea sapida Muell. Arg) and Khasi mandarin orange (Citrus reticulata Blanco), and blossom of seeded banana (Musa balbisiana, ABB). Highest yield of fiber was obtained from Burmese grape peel (BGPL, 79.94 ± 0.41 g/100 g) and seeded banana blossom (BB 77.18 ± 0.20 g/100 g). The total dietary fiber content (TDF) was highest in fiber fraction derived from pineapple pomace (PNPM, 79.76 ± 0.42 g/100 g) and BGPL (67.27 ± 0.39 g/100 g). All the samples contained insoluble dietary fiber as the major fiber fraction. The fiber samples showed good water holding, oil holding and swelling capacities. The fiber samples exhibited antioxidant activity. All the samples showed good results for glucose adsorption, amylase activity inhibition, glucose diffusion rate and glucose diffusion reduction rate index.

Mutagenicity of drinking water sampled from the Yangtze River and Hanshui River (Wuhan section) and correlations with water quality parameters.

PubMed

Lv, Xuemin; Lu, Yi; Yang, Xiaoming; Dong, Xiaorong; Ma, Kunpeng; Xiao, Sanhua; Wang, Yazhou; Tang, Fei

2015-03-31

A total of 54 water samples were collected during three different hydrologic periods (level period, wet period, and dry period) from Plant A and Plant B (a source for Yangtze River and Hanshui River water, respectively), and several water parameters, such as chemical oxygen demand (COD), turbidity, and total organic carbon (TOC), were simultaneously analyzed. The mutagenicity of the water samples was evaluated using the Ames test with Salmonella typhimurium strains TA98 and TA100. According to the results, the organic compounds in the water were largely frame-shift mutagens, as positive results were found for most of the tests using TA98. All of the finished water samples exhibited stronger mutagenicity than the relative raw and distribution water samples, with water samples collected from Plant B presenting stronger mutagenic strength than those from Plant A. The finished water samples from Plant A displayed a seasonal-dependent variation. Water parameters including COD (r = 0.599, P = 0.009), TOC (r = 0.681, P = 0.02), UV254 (r = 0.711, P = 0.001), and total nitrogen (r = 0.570, P = 0.014) exhibited good correlations with mutagenicity (TA98), at 2.0 L/plate, which bolsters the argument of the importance of using mutagenicity as a new parameter to assess the quality of drinking water.

Mutagenicity of drinking water sampled from the Yangtze River and Hanshui River (Wuhan section) and correlations with water quality parameters

PubMed Central

Lv, Xuemin; Lu, Yi; Yang, Xiaoming; Dong, Xiaorong; Ma, Kunpeng; Xiao, Sanhua; Wang, Yazhou; Tang, Fei

2015-01-01

A total of 54 water samples were collected during three different hydrologic periods (level period, wet period, and dry period) from Plant A and Plant B (a source for Yangtze River and Hanshui River water, respectively), and several water parameters, such as chemical oxygen demand (COD), turbidity, and total organic carbon (TOC), were simultaneously analyzed. The mutagenicity of the water samples was evaluated using the Ames test with Salmonella typhimurium strains TA98 and TA100. According to the results, the organic compounds in the water were largely frame-shift mutagens, as positive results were found for most of the tests using TA98. All of the finished water samples exhibited stronger mutagenicity than the relative raw and distribution water samples, with water samples collected from Plant B presenting stronger mutagenic strength than those from Plant A. The finished water samples from Plant A displayed a seasonal-dependent variation. Water parameters including COD (r = 0.599, P = 0.009), TOC (r = 0.681, P = 0.02), UV254 (r = 0.711, P = 0.001), and total nitrogen (r = 0.570, P = 0.014) exhibited good correlations with mutagenicity (TA98), at 2.0 L/plate, which bolsters the argument of the importance of using mutagenicity as a new parameter to assess the quality of drinking water. PMID:25825837

Psychometric evaluation of the Swedish version of Rosenberg's self-esteem scale.

PubMed

Eklund, Mona; Bäckström, Martin; Hansson, Lars

2018-04-01

The widely used Rosenberg's self-esteem scale (RSES) has not been evaluated for psychometric properties in Sweden. This study aimed at analyzing its factor structure, internal consistency, criterion, convergent and discriminant validity, sensitivity to change, and whether a four-graded Likert-type response scale increased its reliability and validity compared to a yes/no response scale. People with mental illness participating in intervention studies to (1) promote everyday life balance (N = 223) or (2) remedy self-stigma (N = 103) were included. Both samples completed the RSES and questionnaires addressing quality of life and sociodemographic data. Sample 1 also completed instruments chosen to assess convergent and discriminant validity: self-mastery (convergent validity), level of functioning and occupational engagement (discriminant validity). Confirmatory factor analysis (CFA), structural equation modeling, and conventional inferential statistics were used. Based on both samples, the Swedish RSES formed one factor and exhibited high internal consistency (>0.90). The two response scales were equivalent. Criterion validity in relation to quality of life was demonstrated. RSES could distinguish between women and men (women scoring lower) and between diagnostic groups (people with depression scoring lower). Correlations >0.5 with variables chosen to reflect convergent validity and around 0.2 with variables used to address discriminant validity further highlighted the construct validity of RSES. The instrument also showed sensitivity to change. The Swedish RSES exhibited a one-component factor structure and showed good psychometric properties in terms of good internal consistency, criterion, convergent and discriminant validity, and sensitivity to change. The yes/no and the four-graded Likert-type response scales worked equivalently.

Rheological and fracturing characteristics of a novel sulfonated hydroxypropyl guar gum.

PubMed

Qiu, Liewei; Shen, Yiding; Wang, Tao; Wang, Chen

2018-05-15

A series of sulfonated hydroxypropyl guar gum (SHG) samples with different degrees of substitution (DSs) were prepared, and the SHG solution and SHG fracturing fluid were prepared and analyzed. The SHG aqueous solutions with different DSs all exhibit shear thinning behavior, which is well correlated with the Ostwald-deWaele model. Owing to the electrostatic repulsion of SHG molecular chains, SHG solutions with a higher DS will exhibit weaker thixotropic performance and strong anti-salinity ability. In addition, the SHG fracturing fluids, which were formed by interactions between SHG and organic zirconium, exhibit good temperature- and shear-resistant properties, proppant suspension properties, and salt tolerance. Furthermore, SHG gel-breaking fluids show low interfacial and surface tensions, with low residue content and small core permeability damage. These results provide useful indicators for the applications of SHG in the oil field industry. Copyright © 2017. Published by Elsevier B.V.

Improved conductivity of carbon-nano-fiber (CNF)/polytetrafluoroethylene (PTFE) composite

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

Chandra, Sarita; Kalra, G. S.; Pushkar, Vinay K.

2016-05-23

A series of CNF/PTFE composite loaded with different weight % of CNFs as 0.01, 0.02, 0.03, 0.05, 1, 2, 3, 4, 5 into PTFE is fabricated. In this work, the 5wt% heat-treated CNFs were used as filler in PTFE. Current-voltage (I-V) study of the samples confirmed the samples as conducting composite. In scanning electron microscope (SEM) study, the conducting CNFs channels were observed from upper surface to inside throughout the polymer matrix. A sintered composite of 5 wt% loading of CNFs showed an improved conductivity and SEM image exhibited a good binding of CNFs into PTFE.

Thickness determination of biological samples with a zeta-calibrated scanning tunneling microscope.

PubMed Central

Wang, Z H; Hartmann, T; Baumeister, W; Guckenberger, R

1990-01-01

A single-tube scanning tunneling microscope has been zeta-calibrated by using atomic steps of crystalline gold and was used for measuring the thickness of two biological samples, metal-coated as well as uncoated. The hexagonal surface layer of the bacterium Deinococcus radiodurans with an open network-type structure shows thickness values that are strongly influenced by the substrate and the preparation method. In contrast, the thickness of the purple membrane of Halobacterium halobium with its densely packed less-corrugated structure exhibits very little variation in thickness in coated preparations and the values obtained are in good agreement with x-ray data. Images PMID:2251276

Ferrofluids based on Co-Fe-Si-B amorphous nanoparticles

NASA Astrophysics Data System (ADS)

Wang, Tianqi; Bian, Xiufang; Yang, Chuncheng; Zhao, Shuchun; Yu, Mengchun

2017-03-01

Magnetic Co-Fe-Si-B amorphous nanoparticles were successfully synthesized by chemical reduction method. ICP, XRD, DSC, and TEM were used to investigate the composition, structure and morphology of Co-Fe-Si-B samples. The results show that the Co-Fe-Si-B samples are amorphous, which consist of nearly spherical nanoparticles with an average particle size about 23 nm. VSM results manifest that the saturation magnetization (Ms) of Co-Fe-Si-B samples ranges from 46.37 to 62.89 emu/g. Two kinds of ferrofluids (FFs) were prepared by dispersing Co-Fe-Si-B amorphous nanoparticles and CoFe2O4 nanoparticles in kerosene and silicone oil, respectively. The magnetic properties, stability and viscosity of the FFs were investigated. The FFs with Co-Fe-Si-B samples have a higher Ms and lower coercivity (Hc) than FFs with CoFe2O4 sample. Under magnetic field, the silicone oil-based FFs exhibit high stability. The viscosity of FFs under different applied magnetic fields was measured by a rotational viscometer, indicating that FFs with Co-Fe-Si-B particles present relative strong response to an external magnetic field. The metal-boride amorphous alloy nanoparticles have potential applications in the preparation of magnetic fluids with good stability and good magnetoviscous properties.

Phytochemical and Biological Activities of Four Wild Medicinal Plants

PubMed Central

Ahmad, Shabir; AbdEl-Salam, Naser M.; Fouad, H.; Rehman, Najeeb Ur; Hussain, Hidayat; Saeed, Wajid

2014-01-01

The fruits of four wild plants, namely, Capparis decidua, Ficus carica, Syzygium cumini, and Ziziphus jujuba, are separately used as traditional dietary and remedial agents in remote areas of Khyber Pakhtunkhwa, Pakistan. The results of our study on these four plants revealed that the examined fruits were a valuable source of nutraceuticals and exhibited good level of antimicrobial activity. The fruits of these four investigated plants are promising source of polyphenols, flavonoids, alkaloids, terpenoids, and saponins. These four plants' fruits are good sources of iron, zinc, copper, manganese, selenium, and chromium. It was also observed that these fruits are potential source of antioxidant agent and the possible reason could be that these samples had good amount of phytochemicals. Hence, the proper propagation, conservation, and chemical investigation are recommended so that these fruits should be incorporated for the eradication of food and health related problems. PMID:25374941

Direct fabrication of 3D graphene on nanoporous anodic alumina by plasma-enhanced chemical vapor deposition

PubMed Central

Zhan, Hualin; Garrett, David J.; Apollo, Nicholas V.; Ganesan, Kumaravelu; Lau, Desmond; Prawer, Steven; Cervenka, Jiri

2016-01-01

High surface area electrode materials are of interest for a wide range of potential applications such as super-capacitors and electrochemical cells. This paper describes a fabrication method of three-dimensional (3D) graphene conformally coated on nanoporous insulating substrate with uniform nanopore size. 3D graphene films were formed by controlled graphitization of diamond-like amorphous carbon precursor films, deposited by plasma-enhanced chemical vapour deposition (PECVD). Plasma-assisted graphitization was found to produce better quality graphene than a simple thermal graphitization process. The resulting 3D graphene/amorphous carbon/alumina structure has a very high surface area, good electrical conductivity and exhibits excellent chemically stability, providing a good material platform for electrochemical applications. Consequently very large electrochemical capacitance values, as high as 2.1 mF for a sample of 10 mm3, were achieved. The electrochemical capacitance of the material exhibits a dependence on bias voltage, a phenomenon observed by other groups when studying graphene quantum capacitance. The plasma-assisted graphitization, which dominates the graphitization process, is analyzed and discussed in detail. PMID:26805546

Hybrid Mesoporous Silica-Based Drug Carrier Nanostructures with Improved Degradability by Hydroxyapatite.

PubMed

Hao, Xiaohong; Hu, Xixue; Zhang, Cuimiao; Chen, Shizhu; Li, Zhenhua; Yang, Xinjian; Liu, Huifang; Jia, Guang; Liu, Dandan; Ge, Kun; Liang, Xing-Jie; Zhang, Jinchao

2015-10-27

Potential bioaccumulation is one of the biggest limitations for silica nanodrug delivery systems in cancer therapy. In this study, a mesoporous silica nanoparticles/hydroxyapatite (MSNs/HAP) hybrid drug carrier, which enhanced the biodegradability of silica, was developed by a one-step method. The morphology and structure of the nanoparticles were characterized by TEM, DLS, FT-IR, XRD, N2 adsorption-desorption isotherms, and XPS, and the drug loading and release behaviors were tested. TEM and ICP-OES results indicate that the degradability of the nanoparticles has been significantly improved by Ca(2+) escape from the skeleton in an acid environment. The MSNs/HAP sample exhibits a higher drug loading content of about 5 times that of MSNs. The biological experiment results show that the MSNs/HAP not only exhibits good biocompatibility and antitumor effect but also greatly reduces the side effects of free DOX. The as-synthesized hybrid nanoparticles may act as a promising drug delivery system due to their good biocompatibility, high drug loading efficiency, pH sensitivity, and excellent biodegradability.

Fabrication of polysiloxane-modified polyurethane sponge as low-cost organics/water separation and selective absorption material.

PubMed

Cui, Zhengshan; He, Wanxia; Liu, Jun; Wei, Wei; Jiang, Liang; Huang, Jun; Lv, Xiaomeng

2016-10-01

Through sol-gel and dip-coating processes, commercial polyurethane sponge modified by polysiloxane was fabricated under low temperature (60 °C) and atmosphere. The contact angle of the obtained polysiloxane/polyurethane sponge is 145 ± 5°. Hence, the polysiloxane/polyurethane sponge could float on water and selectively absorb organics from the surface of the water, indicating simultaneous properties of hydrophobicity and oleophilicity. The absorbent maximum value is 50-150 times of its own weight. The polysiloxane/polyurethane sponge exhibited excellent recyclability, which could be reused by squeezing the sponge due to its high mechanical stability and flexibility. Thermogravimetry-differential thermal analysis test indicated that the polysiloxane/polyurethane sponge exhibited good thermal stability and the stable contact angle of samples tested under increasing temperature indicated its good weather resistance. Due to the commercial property of polyurethane sponge and easy-handling of polysiloxane, the polysiloxane/polyurethane sponge can be easily scaled up to recover a large-area oil spill in water and further work based on the designed equipment has been under consideration.

Fabrication of 3D honeycomb-like porous polyurethane-functionalized reduced graphene oxide for detection of dopamine.

PubMed

Vilian, A T Ezhil; An, Suyeong; Choe, Sang Rak; Kwak, Cheol Hwan; Huh, Yun Suk; Lee, Jonghwi; Han, Young-Kyu

2016-12-15

A three dimensional reduced graphene oxide/polyurethane (RGO-PU) porous material with connected pores was prepared by physical adsorption of RGO onto the surface of porous PU. The porous PU was prepared by directional melt crystallization of a solvent, which produced high pores with controlled orientation. The prepared RGO-PU was characterized by scanning electron microscopy, spectroscopy and electro-chemical methods. The RGO-PU porous material revealed better electrochemical performance, which might be attributed to the robust structure, superior conductivity, large surface area, and good flexibility. Differential pulse voltammetry (DPV) analysis of DA using the RGO-PU exhibited a linear response range over a wide DA concentration of 100-1150pM, with the detection limit of 1pM. This sensor exhibited outstanding anti-interference ability towards co-existing molecules with good stability, sensitivity, and reproducibility. Furthermore, the fabricated sensor was successfully applied for the quantitative analysis of DA in human serum and urine samples with acceptable recovery, which indicates its feasibility for practical application. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct fabrication of 3D graphene on nanoporous anodic alumina by plasma-enhanced chemical vapor deposition.

PubMed

Zhan, Hualin; Garrett, David J; Apollo, Nicholas V; Ganesan, Kumaravelu; Lau, Desmond; Prawer, Steven; Cervenka, Jiri

2016-01-25

High surface area electrode materials are of interest for a wide range of potential applications such as super-capacitors and electrochemical cells. This paper describes a fabrication method of three-dimensional (3D) graphene conformally coated on nanoporous insulating substrate with uniform nanopore size. 3D graphene films were formed by controlled graphitization of diamond-like amorphous carbon precursor films, deposited by plasma-enhanced chemical vapour deposition (PECVD). Plasma-assisted graphitization was found to produce better quality graphene than a simple thermal graphitization process. The resulting 3D graphene/amorphous carbon/alumina structure has a very high surface area, good electrical conductivity and exhibits excellent chemically stability, providing a good material platform for electrochemical applications. Consequently very large electrochemical capacitance values, as high as 2.1 mF for a sample of 10 mm(3), were achieved. The electrochemical capacitance of the material exhibits a dependence on bias voltage, a phenomenon observed by other groups when studying graphene quantum capacitance. The plasma-assisted graphitization, which dominates the graphitization process, is analyzed and discussed in detail.

TL and OSL characterization of Eu3+ doped Y2O3: Application in dosimetry

NASA Astrophysics Data System (ADS)

Shivaramu, N. J.; Coetsee, E.; Swart, H. C.

2018-05-01

Thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of beta irradiated Eu3+ doped Y2O3 nanophosphor have been investigated in this paper. The Eu3+ doped Y2O3 nanophosphor was synthesized by solution combustion technique and synthesized material was annealed at 900°C. The annealed materials were exposed to β-ray for various dose. TL glow with prominent peak at 403 K and weak glow peak at 660 K were observed in all irradiated samples. It is found that TL glow peaks intensity linearly increases with increase in β-dose from 8.125 - 40.625 Gy. The TL kinetic parameters were calculated using glow curve deconvoluted (GCD) and peak shape methods. The TL glows exhibits general order kinetics. Intense continuous wave optical stimulated luminescence (CW-OSL) was observed in the sample. These material exhibits linearity at low dose, good reproducibility and response of intense OSL and hence, these results suggests that this material may be suitable for dosimetry applications.

Biodegradability and swelling capacity of kaolin based chitosan-g-PHEMA nanocomposite hydrogel.

PubMed

Pradhan, Arun Kumar; Rana, Pradeep Kumar; Sahoo, Prafulla Kumar

2015-03-01

Chitosan, a natural biopolymer, obtained by alkaline deacetylation of chitin, exhibits excellent biological properties such as biodegradability, immunological and antibacterial activity. Recently, there has been a growing interest in the chemical modification of chitosan in order to widen its applications. The chemical modification of chitosan has been achieved via grafting of monomer, 2-hydroxyethyl methacrylate (HEMA) in the presence of the initiator, ammonium persulfate (APS) and kaolin was added to improve the mechanical strength of the newly developed nanocomposites hydrogel. The so prepared grafted nanocomposites hydrogel was characterized by FTIR, XRD, SEM, TEM and TGA. The equilibrium water content (EWC) of the samples were measured at different pH ranges 6.5-8.0 and found optimum at pH 7.5 for biomedical applications. Further, the biodegradability of the samples was studied at different time intervals from 15 days to 1 year but, the kaolin based nanohydrogels exhibited good biodegradability. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of the acute toxicities of physicochemical pretreatment and advanced oxidation processes applied to dairy effluents on activated sludge.

PubMed

Sivrioğlu, Özge; Yonar, Taner

2015-04-01

In this study, the acute toxicities of raw, physicochemical pre-treated, ozonated, and Fenton reagent applied samples of dairy wastewater toward activated sludge microorganisms, evaluated using the International Organization for Standardization's respiration inhibition test (ISO 8192), are presented. Five-day biological oxygen demand (BOD5) was measured to determine the biodegradability of physicochemical treatment, ozonation, Fenton oxidation or no treatment (raw samples) of dairy wastewater. Chemical pretreatment positively affected biodegradability, and the inhibition exhibited by activated sludge was removed to a considerable degree. Ozonation and the Fenton process exhibited good chemical oxygen demand removal (61%) and removal of toxins. Low sludge production was observed for the Fenton process applied to dairy effluents. We did not determine the inhibitory effect of the Fenton-process on the activated sludge mixture. The pollutant-removal efficiencies of the applied processes and their associated operating costs were determined. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Validation of a HPLC method for determination of hydroxymethylfurfural in crude palm oil.

PubMed

Ariffin, Abdul Azis; Ghazali, H M; Kavousi, Parviz

2014-07-01

For the first time 5-hydroxymethyl-2-furaldehyde (HMF) was separated from crude palm oil (CPO), and its authenticity was determined using an RP-HPLC method. Separation was accomplished with isocratic elution of a mobile phase comprising water and methanol (92:8 v/v) on a Purospher Star RP-18e column (250mm×4.6mm, 5.0μm). The flow rate was adjusted to 1ml/min and detection was performed at 284nm. The method was validated, and results obtained exhibit a good recovery (95.58% to 98.39%). Assessment of precision showed that the relative standard deviations (RSD%) of retention times and peak areas of spiked samples were less than 0.59% and 2.66%, respectively. Further, the limit of detection (LOD) and LOQ were 0.02, 0.05mg/kg, respectively, and the response was linear across the applied ranges. The crude palm oil samples analysed exhibited HMF content less than 2.27mg/kg. Copyright © 2014 Elsevier Ltd. All rights reserved.

Integrating diffusion maps with umbrella sampling: Application to alanine dipeptide

NASA Astrophysics Data System (ADS)

Ferguson, Andrew L.; Panagiotopoulos, Athanassios Z.; Debenedetti, Pablo G.; Kevrekidis, Ioannis G.

2011-04-01

Nonlinear dimensionality reduction techniques can be applied to molecular simulation trajectories to systematically extract a small number of variables with which to parametrize the important dynamical motions of the system. For molecular systems exhibiting free energy barriers exceeding a few kBT, inadequate sampling of the barrier regions between stable or metastable basins can lead to a poor global characterization of the free energy landscape. We present an adaptation of a nonlinear dimensionality reduction technique known as the diffusion map that extends its applicability to biased umbrella sampling simulation trajectories in which restraining potentials are employed to drive the system into high free energy regions and improve sampling of phase space. We then propose a bootstrapped approach to iteratively discover good low-dimensional parametrizations by interleaving successive rounds of umbrella sampling and diffusion mapping, and we illustrate the technique through a study of alanine dipeptide in explicit solvent.

Rapid and sensitive analysis of polychlorinated biphenyls and acrylamide in food samples using ionic liquid-based in situ dispersive liquid-liquid microextraction coupled to headspace gas chromatography.

PubMed

Zhang, Cheng; Cagliero, Cecilia; Pierson, Stephen A; Anderson, Jared L

2017-01-20

A simple and rapid ionic liquid (IL)-based in situ dispersive liquid-liquid microextraction (DLLME) method was developed and coupled to headspace gas chromatography (HS-GC) employing electron capture (ECD) and mass spectrometry (MS) detection for the analysis of polychlorinated biphenyls (PCBs) and acrylamide at trace levels from milk and coffee samples. The chemical structures of the halide-based ILs were tailored by introducing various functional groups to the cations to evaluate the effect of different structural features on the extraction efficiency of the target analytes. Extraction parameters including the molar ratio of IL to metathesis reagent and IL mass were optimized. The effects of HS oven temperature and the HS sample vial volume on the analyte response were also evaluated. The optimized in situ DLLME method exhibited good analytical precision, good linearity, and provided detection limits down to the low ppt level for PCBs and the low ppb level for acrylamide in aqueous samples. The matrix-compatibility of the developed method was also established by quantifying acrylamide in brewed coffee samples. This method is much simpler and faster compared to previously reported GC-MS methods using solid-phase microextraction (SPME) for the extraction/preconcentration of PCBs and acrylamide from complex food samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermoluminescence (TL) dosimeter of dysprosium doped strontium borate glass for different glass modifiers (Na, Li, Ca) subjected from 1 to 9 Gy doses

NASA Astrophysics Data System (ADS)

Hamzah, S. A.; Saeed, M. A.; Wagiran, H.; Hashim, I. H.

2017-10-01

This article reports TL response for different glass modifier and doping concentration. Alkali oxides (Na2O and Li2O) and alkali earth oxide (CaO) will be used as a glass modifier for strontium borate based glass. The samples were prepared by melt quenching technique. Dy2O3 concentrations ranging from 0.00 to 0.70 mol% and exposure doses of 1 to 9 Gy will be varied. All glass samples exhibit the prominent peak temperature positioned at 186 oC to 232 oC. From all the samples, one of the samples shows an excellent linearity dose response, higher TL and show good reproducibility after 5 cycles exposure which is sodium strontium borate doped with 0.1 mol% Dy2O3 (optimum concentration).

Overcoming Ehrlich-Schwöbel barrier in (1 1 1)A GaAs molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Ritzmann, Julian; Schott, Rüdiger; Gross, Katherine; Reuter, Dirk; Ludwig, Arne; Wieck, Andreas D.

2018-01-01

In this work, we first study the effect of different growth parameters on the molecular beam epitaxy (MBE) growth of GaAs layers on (1 1 1)A oriented substrates. After that we present a method for the MBE growth of atomically smooth layers by sequences of growth and annealing phases. The samples exhibit low surface roughness and good electrical properties shown by atomic force microscopy (AFM), scanning electron microscopy (SEM) and van-der-Pauw Hall measurements.

Residues and potential ecological risks of veterinary antibiotics in manures and composts associated with protected vegetable farming.

PubMed

Zhang, Haibo; Luo, Yongming; Wu, Longhua; Huang, Yujuan; Christie, Peter

2015-04-01

Veterinary antibiotics (VAs) are emerging contaminants and enter into soil principally by agricultural application of organic fertilizer. A total of 33 solid animal manures and 17 compost samples from protected vegetable farms in nine areas of China were analyzed for the antibiotic classes of tetracyclines, fluoroquinolones, sulfonamides, and macrolides (17 substances in total). Oxytetracycline was found as a dominant compound in the samples, and its highest concentration reached 416.8 mg kg(-1) in a chicken manure sample from Shouguang, Shandong Province. Among the samples, animal manures (especially pig manure) contained higher VA residues than composts. However, fluoroquinolones exhibited higher persistence in the compost samples than other antibiotic classes. This is particularly the case in the rice husk compost, which contained the highest level of ofloxacin and ciprofloxacin (1334.5 and 1717.4 μg kg(-1) on average, respectively). The veterinary antibiotic profile in the risk husk compost had a good relationship with that in the corresponding manures. The refined commercial compost had the lowest VA residues among the compost samples in general. This implied that composting process might be important to reduce the antibiotic residue. High residue of antibiotics in soil was assumed to be a hazard to ecosystem. This is especially noticeable under current application rates (150 t ha(-1) a(-1)) in protected vegetable farming because over half of the samples exhibited a risk quotient (RQ) >1 for one or more antibiotics.

Semiconducting compounds and devices incorporating same

DOEpatents

Marks, Tobin J; Facchetti, Antonio; Boudreault, Pierre-Luc; Miyauchi, Hiroyuki

2014-06-17

Disclosed are molecular and polymeric compounds having desirable properties as semiconducting materials. Such compounds can exhibit desirable electronic properties and possess processing advantages including solution-processability and/or good stability. Organic transistor and photovoltaic devices incorporating the present compounds as the active layer exhibit good device performance.

Semiconducting compounds and devices incorporating same

DOEpatents

Marks, Tobin J.; Facchetti, Antonio; Boudreault, Pierre-Luc; Miyauchi, Hiroyuki

2016-01-19

Disclosed are molecular and polymeric compounds having desirable properties as semiconducting materials. Such compounds can exhibit desirable electronic properties and possess processing advantages including solution-processability and/or good stability. Organic transistor and photovoltaic devices incorporating the present compounds as the active layer exhibit good device performance.

Screening and Characterization of Cold-Active β-Galactosidase Producing Psychrotrophic Enterobacter ludwigii from the Sediments of Arctic Fjord.

PubMed

Alikkunju, Aneesa P; Sainjan, Neethu; Silvester, Reshma; Joseph, Ajith; Rahiman, Mujeeb; Antony, Ally C; Kumaran, Radhakrishnan C; Hatha, Mohamed

2016-10-01

Low-temperature-tolerant microorganisms and their cold-active enzymes could be an innovative and invaluable tool in various industrial applications. In the present study, bacterial isolates from the sediment samples of Kongsfjord, Norwegian Arctic, were screened for β-galactosidase production. Among the isolates, KS25, KS85, KS60, and KS92 have shown good potential in β-galactosidase production at 20 °C. 16SrRNA gene sequence analysis revealed the relatedness of the isolates to Enterobacter ludwigii. The optimum growth temperature of the isolate was 25 °C. The isolate exhibited good growth and enzyme production at a temperature range of 15-35 °C, pH 5-10. The isolate preferred yeast extract and lactose for the maximum growth and enzyme production at conditions of pH 7.0, temperature of 25 °C, and agitation speed of 100 rpm. The growth and enzyme production was stimulated by Mn 2+ and Mg 2+ and strongly inhibited by Zn 2+ , Ni 2+ , and Cu + . β-Galactosidases with high specific activity at low temperatures are very beneficial in food industry to compensate the nutritional problem associated with lactose intolerance. The isolate exhibited a remarkable capability to utilize clarified whey, an industrial pollutant, for good biomass and enzyme yield and hence could be well employed in whey bioremediation.

Probiotic Properties of Lactobacillus plantarum RYPR1 from an Indigenous Fermented Beverage Raabadi

PubMed Central

Yadav, Ruby; Puniya, Anil K.; Shukla, Pratyoosh

2016-01-01

Present study documents the potential probiotic Lactobacillus isolated from indigenous fermented beverage Raabadi, consumed during summers in Haryana and Rajasthan regions of India. A total of five Raabadi samples were collected aseptically and 54 isolates were purified using MRS medium. All the isolates were assessed for tolerance to low pH and bile salts. It was observed that out of 54 only 24 isolates could survive the simulated gastric conditions. These isolates were further evaluated in vitro for cell surface hydrophobicity, cell surface hydrophobicity, hypocholesteramic activity, anti-oxidative potential, BSH activity, antagonistic activity, and antibiotic resistance profile. In addition, the confirmation of phenol resistance was also done. On the basis of results obtained, the survival rate of isolates was noted and six isolates were finally selected for further studies. Among them Lactobacillus plantarum RYPR1 and RYPC7 showed good survival at pH 2 which shows good acid tolerance. Moreover, L. plantarum RYPR1 showed the highest hydrophobicity (79.13%) and represented the deconjugation of bile salts, which help in their adhesion to epithelial cells and colonization. Furthermore, RYPR1 also exhibited highest cholesterol reduction (59%) and subsequent analysis of results revealed that the above mentioned isolates further exhibit a good hypocholesterolemic effect and could be possibly used to prevent hypercholesterolemia. The present study divulges that L. plantarum RYPR1 has an excellent probiotic potential. PMID:27818658

Rapid determination of caffeine in one drop of beverages and foods using drop-to-drop solvent microextraction with gas chromatography/mass spectrometry.

PubMed

Shrivas, Kamlesh; Wu, Hui-Fen

2007-11-02

A simple and rapid sample cleanup and preconcentration method for the quantitative determination of caffeine in one drop of beverages and foods by gas chromatography/mass spectrometry (GC/MS) has been proposed using drop-to-drop solvent microextraction (DDSME). The best optimum experimental conditions for DDSME were: chloroform as the extraction solvent, 5 min extraction time, 0.5 microL exposure volume of the extraction phase and no salt addition at room temperature. The optimized methodology exhibited good linearity between 0.05 and 5.0 microg/mL with correlation coefficient of 0.980. The relative standard deviation (RSD) and limits of detection (LOD) of the DDSME/GC/MS method were 4.4% and 4.0 ng/mL, respectively. Relative recovery of caffeine in beverages and foods were found to be 96.6-101%, which showing good reliability of this method. This DDSME excludes the major disadvantages of conventional method of caffeine extraction, like large amount of organic solvent and sample consumption and long sample pre-treatment process. So, this approach proves that the DDSME/GC/MS technique can be applied as a simple, fast and feasible diagnosis tool for environmental, food and biological application for extremely small amount of real sample analysis.

Preparation and evaluation of ageing effect of Cu-Al-Be-Mn shape memory alloys

NASA Astrophysics Data System (ADS)

Shivasiddaramaiah, A. G.; Mallik, U. S.; Mahato, Ranjit; Shashishekar, C.

2018-04-01

10-14 wt. % of aluminum, 0.3-0.6 wt. % of beryllium and 0.1-0.4 wt. % of manganese and remaining copper melted in the induction furnace through ingot metallurgy. The prepared SMAs are subjected to homogenization. It was observed that the samples exhibits β-phase at high temperature and shape memory effect after going through step quenching to a low temperature. Scanning Electron Microscope, DSC, bending test were performed on the samples to determine the microstructure, transformation temperatures and shape memory effect respectively. The alloy exhibit good shape memory effect, up to around 96% strain recovery by shape memory effect. The ageing is performed on the specimen prepared according to ASTM standard for testing micro-hardness and tensile test. Precipitation hardening method was employed to age the samples and they were aged at different temperature and at different times followed by quenching. Various forms of precipitates were formed. It was found that the formation rate and transformation temperature increased with ageing time, while the amount of precipitate had an inverse impact on strain recovery by shape memory effect. The result expected is to increase in mechanical properties of the material such as hardness.

Effects of 4 Probiotic Strains in Coculture with Traditional Starters on the Flavor Profile of Yogurt.

PubMed

Tian, Huaixiang; Shen, Yongbo; Yu, Haiyan; He, Yujie; Chen, Chen

2017-07-01

To study the influence of probiotics on the flavor profile of yogurt, 4 probiotics, including Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, and Lactobacillus casei, were cofermented with traditional starters. The changes of bacterial growth, acid contents and volatile compounds of yogurt were investigated during fermentation and refrigerated storage. The strains that exhibited a low growth rate in milk did not significantly affect the bacterial population dynamics, acidity, or organic acid content during fermentation and storage. However, high viability and enhancement of postacidification were clearly observed in the samples that contained strains with a high growth rate in milk, particularly L. casei. A total of 45 volatile compounds, detected in most samples, were identified by headspace solid-phase micro-extraction followed by gas chromatography-mass spectrometry. Among these compounds, ketones and aldehydes were the most abundant. The presence of either L. rhamnosus or L. plantarum did not significantly affect the major volatile compounds, while contributions of L. casei and L. acidophilus were found in the formation of minor volatile metabolites. Electronic nose measurements exhibited a good discrimination of samples that contained different probiotics during refrigerated storage. © 2017 Institute of Food Technologists®.

Characterisation of DLC films deposited using titanium isopropoxide (TIPOT) at different flow rates.

PubMed

Said, R; Ali, N; Ghumman, C A A; Teodoro, O M N D; Ahmed, W

2009-07-01

In recent years, there has been growing interest in the search for advanced biomaterials for biomedical applications, such as human implants and surgical cutting tools. It is known that both carbon and titanium exhibit good biocompatibility and have been used as implants in the human body. It is highly desirable to deposit biocompatible thin films onto a range of components in order to impart biocompatibility and to minimise wear in implants. Diamond like carbon (DLC) is a good candidate material for achieving biocompatibility and low wear rates. In this study, thin films of diamond-like-carbon DLC were deposited onto stainless steel (316) substrates using C2H2, argon and titanium isopropoxide (TIPOT) precursors. Argon was used to generate the plasma in the plasma enhanced vapour deposition (PECVD) system. A critical coating feature governing the performance of the component during service is film thickness. The as-grown films were in the thickness range 90-100 nm and were found to be dependent on TIPOT flow rate. Atomic force microscopy (AFM) was used to characterise the surface roughness of the samples. As the flow rate of TIPOT increased the average roughness was found to increase in conjunction with the film thickness. Raman spectroscopy was used to investigate the chemical structure of amorphous carbon matrix. Surface tension values were calculated using contact angle measurements. In general, the trend of the surface tension results exhibited an opposite trend to that of the contact angle. The elemental composition of the samples was characterised using a VG ToF SIMS (IX23LS) instrument and X-ray photoelectron spectroscopy (XPS). Surprisingly, SIMS and XPS results showed that the DLC samples did not show evidence of titanium since no peaks representing to titanium appeared on the SIMS/XPS spectra.

Leadership perceptions as a function of race-occupation fit: the case of Asian Americans.

PubMed

Sy, Thomas; Shore, Lynn M; Strauss, Judy; Shore, Ted H; Tram, Susanna; Whiteley, Paul; Ikeda-Muromachi, Kristine

2010-09-01

On the basis of the connectionist model of leadership, we examined perceptions of leadership as a function of the contextual factors of race (Asian American, Caucasian American) and occupation (engineering, sales) in 3 experiments (1 student sample and 2 industry samples). Race and occupation exhibited differential effects for within- and between-race comparisons. With regard to within-race comparisons, leadership perceptions of Asian Americans were higher when race-occupation was a good fit (engineer position) than when race-occupation was a poor fit (sales position) for the two industry samples. With regard to between-race comparisons, leadership perceptions of Asian Americans were low relative to those of Caucasian Americans. Additionally, when race-occupation was a good fit for Asian Americans, such individuals were evaluated higher on perceptions of technical competence than were Caucasian Americans, whereas they were evaluated lower when race-occupation was a poor fit. Furthermore, our results demonstrated that race affects leadership perceptions through the activation of prototypic leadership attributes (i.e., implicit leadership theories). Implications for the findings are discussed in terms of the connectionist model of leadership and leadership opportunities for Asian Americans. Copyright 2010 APA, all rights reserved

Trace analysis of endocrine disrupting compounds in environmental water samples by use of solid-phase extraction and gas chromatography with mass spectrometry detection.

PubMed

Azzouz, Abdelmonaim; Ballesteros, Evaristo

2014-09-19

A novel analytical method using a continuous solid-phase extraction system in combination with gas chromatography-mass spectrometry for the simultaneous separation and determination of endocrine disrupting compounds (EDCs) is reported. The method was applied to major EDCs of various types including parabens, alkylphenols, phenylphenols, bisphenol A and triclosan in water. Samples were preconcentrated by using an automatic solid-phase extraction module containing a sorbent column, and retained analytes eluted with acetonitrile for derivatization with a mixture of N,O-bis(trimethylsilyl)trifluoroacetamide and trimethylchlorosilane. A number of variables potentially influencing recovery of the target compounds such as the type of SPE sorbent (Silica gel, Florisil, RP-C18, Amberlite XAD-2 and XAD-4, Oasis HLB and LiChrolut EN), eluent and properties of the water including pH and ionic strength, were examined. LiChrolut EN was found to be the most efficient sorbent for retaining the analytes, with ∼100% efficiency. The ensuing method was validated with good analytical results including low limits of detection (0.01-0.08ng/L for 100mL of sample) and good linearity (r(2)>0.997) throughout the studied concentration ranges. The method exhibited good accuracy (recoveries of 90-101%) and precision (relative standard deviations less than 7%) in the determination of EDCs in drinking, river, pond, well, swimming pool and waste water. Waste water samples were found to contain the largest number and highest concentrations of analytes (3.2-390ng/L). Copyright © 2014 Elsevier B.V. All rights reserved.

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

Mo-doped V2O5 hierarchical nanorod/nanoparticle core/shell porous microspheres with improved performance for cathode of lithium-ion battery

NASA Astrophysics Data System (ADS)

Yu, Haolin; Zeng, Jianyun; Hao, Wen; Zhou, Peng; Wen, Xiaogang

2018-05-01

Mo-doped V2O5 hierarchical nanorod/nanoparticle core/shell porous microspheres (MVHPMs) were prepared via a simple hydrothermal approach using ammonium metavanadate and ammonium molybdate as precursors followed by a thermal annealing process. The samples were characterized by XRD, SEM, TEM, EDS, and XPS carefully; it confirmed that porous microspheres with uniform Mo doping in the V2O5 matrix were obtained, and it contains an inner core self-assembled with 1D nanorods and outer shell consisting of nanoparticles. A plausible growth mechanism of Mo-doped V2O5 (Mo-V2O5) porous microspheres is suggested. The unique microstructure made the Mo-V2O5 hierarchical microspheres a good cathode material for Li-ion battery. The results indicate the synthesized Mo-V2O5 hierarchical microspheres exhibit well-improved electrochemical performance compared to the undoped samples. It delivers a high initial reversible capacity of 282 mAh g-1 at 0.2 C, 208 mAh g-1 at 2 C, and 111 mAh g-1 at 10 C, and it also exhibits good cycling stabilities; a capacity of 144 mAh g-1 is obtained after 200 cycles at 6 C with a capacity retention of > 82%, which is much high than that of pure V2O5 (95 mAh g-1 with a capacity retention of 72%). [Figure not available: see fulltext.

Effect of Annealing Temperature on Structural, Optical, and Electrical Properties of Sol-Gel Spin-Coating-Derived Cu2ZnSnS4 Thin Films

NASA Astrophysics Data System (ADS)

Hosseinpour, Rabie; Izadifard, Morteza; Ghazi, Mohammad Ebrahim; Bahramian, Bahram

2018-02-01

The effect of annealing temperature on structural, optical, and electrical properties of Cu2ZnSnS4 (CZTS) thin films grown on a glass substrate by spin coating sol-gel technique has been studied. Structural study showed that all samples had kesterite crystalline structure. Scanning electron microscopy images showed that the crystalline quality of the samples was improved by heat treatment. Optical study showed that the energy gap values for the samples ranged from 1.55 eV to 1.78 eV. Moreover, good optical conductivity values (1012 S-1 to 1014 S-1) were obtained for the samples. Investigation of the electrical properties of the CZTS thin films showed that the carrier concentration increased significantly with the annealing temperature. The photoelectrical behavior of the samples revealed that the photocurrent under light illumination increased significantly. Overall, the results show that the CZTS thin films annealed at 500°C had better structural, optical, and electrical properties and that such CZTS thin films are desirable for use as absorber layers in solar cells. The photovoltaic properties of the CZTS layer annealed at 500°C were also investigated and the associated figure of merit calculated. The results showed that the fabricated ZnS-CZTS heterojunction exhibited good rectifying behavior but rather low fill factor.

Magnetic porous carbon derived from a metal-organic framework as a magnetic solid-phase extraction adsorbent for the extraction of sex hormones from water and human urine.

PubMed

Ma, Ruiyang; Hao, Lin; Wang, Junmin; Wang, Chun; Wu, Qiuhua; Wang, Zhi

2016-09-01

An iron-embedded porous carbon material (MIL-53-C) was fabricated by the direct carbonization of MIL-53. The MIL-53-C possesses a high surface area and good magnetic behavior. The structure, morphology, magnetic property, and porosity of the MIL-53-C were studied by scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, and N2 adsorption. With the use of MIL-53-C as the magnetic solid-phase extraction adsorbent, a simple and efficient method was developed for the magnetic solid-phase extraction of three hormones from water and human urine samples before high-performance liquid chromatography with UV detection. The developed method exhibits a good linear response in the range of 0.02-100 ng/mL for water and 0.5-100 ng/mL for human urine samples, respectively. The limit of detection (S/N = 3) for the analytes was 0.005-0.01 ng/mL for water sample and 0.1-0.3 ng/mL for human urine sample. The limit of quantification (S/N = 10) of the analytes were in the range of 0.015-0.030 and 0.3-0.9 ng/mL, respectively. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antibacterial abilities and biocompatibilities of Ti-Ag alloys with nanotubular coatings.

PubMed

Liu, Xingwang; Tian, Ang; You, Junhua; Zhang, Hangzhou; Wu, Lin; Bai, Xizhuang; Lei, Zeming; Shi, Xiaoguo; Xue, Xiangxin; Wang, Hanning

To endow implants with both short- and long-term antibacterial activities without impairing their biocompatibility, novel Ti-Ag alloy substrates with different proportions of Ag (1, 2, and 4 wt% Ag) were generated with nanotubular coverings (TiAg-NT). Unlike commercial pure Ti and titania nanotube, the TiAg-NT samples exhibited short-term antibacterial activity against Staphylococcus aureus ( S. aureus ), as confirmed by scanning electron microscopy and double staining with SYTO 9 and propidium iodide. A film applicator coating assay and a zone of inhibition assay were performed to investigate the long-term antibacterial activities of the samples. The cellular viability and cytotoxicity were evaluated through a Cell Counting Kit-8 assay. Annexin V-FITC/propidium iodide double staining was used to assess the level of MG63 cell apoptosis on each sample. All of the TiAg-NT samples, particularly the nanotube-coated Ti-Ag alloy with 2 wt% Ag (Ti2%Ag-NT), could effectively inhibit bacterial adhesion and kill the majority of adhered S. aureus on the first day of culture. Additionally, the excellent antibacterial abilities exhibited by the TiAg-NT samples were sustained for at least 30 days. Although Ti2%Ag-NT had less biocompatibility than titania nanotube, its performance was satisfactory, as demonstrated by the higher cellular viability and lower cell apoptosis rate obtained with it compared with those achieved with commercial pure Ti. The Ti1%Ag-NT and Ti4%Ag-NT samples did not yield good cell viability. This study indicates that the TiAg-NT samples can prevent biofilm formation and maintain their antibacterial ability for at least 1 month. Ti2%Ag-NT exhibited better antibacterial ability and biocompatibility than commercial pure Ti, which could be attributed to the synergistic effect of the presence of Ag (2 wt%) and the morphology of the nanotubes. Ti2%Ag-NT may offer a potential implant material that is capable of preventing implant-related infection.

Antibacterial abilities and biocompatibilities of Ti–Ag alloys with nanotubular coatings

PubMed Central

Liu, Xingwang; Tian, Ang; You, Junhua; Zhang, Hangzhou; Wu, Lin; Bai, Xizhuang; Lei, Zeming; Shi, Xiaoguo; Xue, Xiangxin; Wang, Hanning

2016-01-01

Purpose To endow implants with both short- and long-term antibacterial activities without impairing their biocompatibility, novel Ti–Ag alloy substrates with different proportions of Ag (1, 2, and 4 wt% Ag) were generated with nanotubular coverings (TiAg-NT). Methods Unlike commercial pure Ti and titania nanotube, the TiAg-NT samples exhibited short-term antibacterial activity against Staphylococcus aureus (S. aureus), as confirmed by scanning electron microscopy and double staining with SYTO 9 and propidium iodide. A film applicator coating assay and a zone of inhibition assay were performed to investigate the long-term antibacterial activities of the samples. The cellular viability and cytotoxicity were evaluated through a Cell Counting Kit-8 assay. Annexin V-FITC/propidium iodide double staining was used to assess the level of MG63 cell apoptosis on each sample. Results All of the TiAg-NT samples, particularly the nanotube-coated Ti–Ag alloy with 2 wt% Ag (Ti2%Ag-NT), could effectively inhibit bacterial adhesion and kill the majority of adhered S. aureus on the first day of culture. Additionally, the excellent antibacterial abilities exhibited by the TiAg-NT samples were sustained for at least 30 days. Although Ti2%Ag-NT had less biocompatibility than titania nanotube, its performance was satisfactory, as demonstrated by the higher cellular viability and lower cell apoptosis rate obtained with it compared with those achieved with commercial pure Ti. The Ti1%Ag-NT and Ti4%Ag-NT samples did not yield good cell viability. Conclusion This study indicates that the TiAg-NT samples can prevent biofilm formation and maintain their antibacterial ability for at least 1 month. Ti2%Ag-NT exhibited better antibacterial ability and biocompatibility than commercial pure Ti, which could be attributed to the synergistic effect of the presence of Ag (2 wt%) and the morphology of the nanotubes. Ti2%Ag-NT may offer a potential implant material that is capable of preventing implant-related infection. PMID:27843315

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.

Application of artificial neural networks to thermal detection of disbonds

NASA Technical Reports Server (NTRS)

Prabhu, D. R.; Howell, P. A.; Syed, H. I.; Winfree, W. P.

1992-01-01

A novel technique for processing thermal data is presented and applied to simulation as well as experimental data. Using a neural network of thermal data classification, good classification accuracies are obtained, and the resulting images exhibit very good contrast between bonded and disbonded locations. In order to minimize the preprocessing required before using the network of classification, the temperature values were directly employed to train a network using data from an on-site testing run of a commercial aircraft. Training was extremely fast, and the resulting classification also agreed reasonably well with an ultrasonic characterization of the panel. The results obtained using one sample show the partially disbonded vertical doubler. The vertical lines along the doubler correspond to the original extent of the doubler obtained using blueprints of the aircraft.

The preparation, cytocompatibility and antimicrobial property of micro/nano structural titanium loading alginate and antimicrobial peptide

NASA Astrophysics Data System (ADS)

Liu, Zhiyuan; Zhong, Mou; Sun, Yuhua; Chen, Junhong; Feng, Bo

2018-03-01

Titanium with hybrid microporous/nanotubes (TMNT) structure on its surface was fabricated by acid etching and subsequently anodization at different voltages. Bovine lactoferricin, a kind of antimicrobial peptide, and sodium alginate (NaAlg) were loaded onto titanium surface through layer by layer assembly. The drug release, cytocompatibility and antimicrobial property against S.aureus and E.coil were studied by release experiment, osteoblast and bacterial cultures. Results indicated that samples with nanotubes of bigger diameter carried more drugs and had better biocompatibility, and drug-loaded samples acquired better biocompatibility compared with drug-free samples. Furthermore, the drug-loaded samples exhibited good initial antimicrobial property, but weak long-term antimicrobial property. Therefore, drug-loaded titanium with micro/nano structure, especially, of big diameter nanotubes, could be a promise material for medical implants, such as internal/external fixation devices.

Color-tunable and white luminescence properties via energy transfer in single-phase KNaCa2(PO4)2:A (A = Ce3+, Eu2+, Tb3+, Mn2+, Sm3+) phosphors.

PubMed

Geng, Dongling; Shang, Mengmeng; Zhang, Yang; Lian, Hongzhou; Lin, Jun

2013-12-02

A series of single-phase phosphors based on KNaCa2(PO4)2 (KNCP):A (A = Ce(3+), Eu(2+), Tb(3+), Mn(2+), Sm(3+)) have been prepared via the Pechini-type sol-gel method. Photoluminescence (PL) and cathodoluminescence (CL) properties of Ce(3+)-, Eu(2+)-, Tb(3+)-, Mn(2+)-, and Sm(3+)-activated KNCP phosphors were investigated. For the A singly doped KNCP samples, they exhibit the characteristic emissions of the A activator. Na(+) ions exhibit the best charge compensation result among Li(+), Na(+), and K(+) ions for Ce(3+)-, Tb(3+)-, and Sm(3+)-doped KNCP samples. The energy transfers from Ce(3+) to Tb(3+) and Mn(2+) ions as well as Eu(2+) to Tb(3+) and Mn(2+) have been validated. The emission colors of KNCP:Ce(3+)/Eu(2+), Tb(3+)/Mn(2+), Na(+) samples can be adjusted by energy transfer process and changing the Tb(3+)/Mn(2+) concentration. More importantly, white light emission in KNCP:Eu(2+), Mn(2+) system has been obtained. The KNCP:Tb(3+), Na(+) sample shows tunable luminescence from blue to cyan and then to green with the change of Tb(3+) concentration due to the cross-relaxation from (5)D3 to (5)D4. A white emission can also be realized in the single-phase KNCP host by reasonably adjusting the doping concentrations of Tb(3+) and Sm(3+) (reddish-orange emission) under low-voltage electron beam excitation. Additionally, the temperature-dependent PL properties of as-prepared phosphors reveal that the KNCP host has good thermal stability. Therefore, the KNCP:A (A = Ce(3+), Eu(2+), Tb(3+), Mn(2+), Sm(3+)) phosphors could be regarded as good candidates for UV W-LEDs and FEDs.

Reconstructing The Star Formation Histories Of Galaxies Through Sed Fitting Using The Dense Basis Method

NASA Astrophysics Data System (ADS)

Iyer, Kartheik; Gawiser, Eric

2017-06-01

The Dense Basis SED fitting method reveals previously inaccessible information about the number and duration of star formation episodes and the timing of stellar mass assembly as well as uncertainties in these quantities, in addition to accurately recovering traditional SED parameters including M*, SFR and dust attenuation. This is done using basis Star Formation Histories (SFHs) chosen by comparing the goodness-of-fit of mock galaxy SEDs to the goodness-of-reconstruction of their SFHs, trained and validated using three independent datasets of mock galaxies at z=1 from SAMs, Hydrodynamic simulations and stochastic realizations. Of the six parametrizations of SFHs considered, we reject the traditional parametrizations of constant and exponential SFHs and suggest four novel improvements, quantifying the bias and scatter of each parametrization. We then apply the method to a sample of 1100 CANDELS GOODS-S galaxies at 110^9 M_sun, in contrast to current simulations. About 40% of the CANDEL galaxies have SFHs whose maximum occurs at or near the epoch of observation. These results are presented in Iyer and Gawiser (2017, ApJ 838 127), available at https://arxiv.org/abs/1702.04371

Magnetic sulfur-doped porous carbon for preconcentration of trace mercury in environmental water prior to ICP-MS detection.

PubMed

Peng, Chuyu; He, Man; Chen, Beibei; Huang, Lijin; Hu, Bin

2017-11-20

A novel magnetic sulfur-doped porous carbon (MSPC) was fabricated via a simple one-step carbonization of a mixture of sucrose, basic magnesium sulfate whiskers and Fe 3 O 4 @SiO 2 nanoparticles. Due to the high S content, the prepared MSPC possessed high adsorption capacity for Hg 2+ (343 mg g -1 ) with good selectivity. Based on this, a method coupling magnetic solid phase extraction (MSPE) with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of trace Hg 2+ in environmental water samples. Various parameters such as pH, desorption solvent and its concentration, desorption volume and time, sample volume, and adsorption time that affect the determination have been optimized. Under the optimal conditions, a high enrichment factor of 100-fold was obtained, the limit of detection (LOD) was found to be 0.52 pg mL -1 with a relative standard deviation (c = 10 pg mL -1 , n = 7) of 7.1%, and a good linearity was obtained within the concentration range of 2-5000 pg mL -1 for Hg 2+ . Besides, the proposed method has very fast adsorption/desorption kinetics, target Hg 2+ could be rapidly adsorbed on the prepared MSPC in 2 min and desorbed from the MSPC in 2 min with the assistance of a permanent magnet. Therefore, the proposed method of MSPE-ICP-MS exhibits good application potential in the determination of trace Hg 2+ in environmental water samples.

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.

Selectivity of hexaphenylbenzene-based hydrocarbon stationary phase with propeller-like conformation for aromatic and aliphatic isomers.

PubMed

Yang, Yinhui; Chang, Zhengfeng; Yang, Xiaohong; Qi, Meiling; Wang, Jinliang

2018-08-03

Herein we report a propeller-like hexaphenylbenzene-based hydrocarbon material (denoted as BT) as the stationary phase for capillary gas chromatography (GC). The statically-coated BT capillary column showed a high column efficiency of 4340 plates m -1 and weak polarity. Owing to its unique conformation, π-electron toroidal delocalization and intrinsic microporosity, the BT stationary phase exhibited interesting selectivity for aromatic compounds over alkanes. Compared with the graphene (G) column, the BT column showed much prolonged retention and high selectivity for aromatic isomers, especially methylnaphthalenes, dimethylnaphthalenes and phenanthrene/anthracene, mainly because of its propeller-like conformation with rich intercalation effects. Moreover, it exhibited good column repeatability (intra-day, inter-day) and reproducibility (between-column) with RSD values on the retention times less than 0.08% for intra-day, 0.32% for inter-day and 3.8% for between-column, respectively. Also, it showed good potential for determination of minor isomer impurities in real samples. To the best of our knowledge, this work presents the first example of employing an neat aromatic hydrocarbon material as the GC stationary phase with high selectivity for analytes of a wide ranging polarity. Copyright © 2018 Elsevier B.V. All rights reserved.

How Many U.S. High School Students Have a Foreign Language Reading "Disability"? Reading Without Meaning and the Simple View.

PubMed

Sparks, Richard L; Luebbers, Julie

Conventional wisdom suggests that students classified as learning disabled will exhibit difficulties with foreign language (FL) learning, but evidence has not supported a relationship between FL learning problems and learning disabilities. The simple view of reading model posits that reading comprehension is the product of word decoding and language comprehension and that there are good readers and 3 types of poor readers-dyslexic, hyperlexic, and garden variety-who exhibit different profiles of strengths and/or deficits in word decoding and language comprehension. In this study, a random sample of U.S. high school students completing first-, second-, and third-year Spanish courses were administered standardized measures of Spanish word decoding and reading comprehension, compared with monolingual Spanish readers from first to eleventh grades, and classified into reader types according to the simple view of reading. The majority of students fit the hyperlexic profile, and no participants fit the good reader profile until they were compared with first- and second-grade monolingual Spanish readers. Findings call into question the practice of diagnosing an FL "disability" before a student engages in FL study.

Development of electrochemical folic acid sensor based on hydroxyapatite nanoparticles

NASA Astrophysics Data System (ADS)

Kanchana, P.; Sekar, C.

2015-02-01

We report the synthesis of hydroxyapatite (HA) nanoparticles (NPs) by a simple microwave irradiation method and its application as sensing element for the precise determination of folic acid (FA) by electrochemical method. The structure and composition of the HA NPs characterized using XRD, FTIR, Raman and XPS. SEM and EDX studies confirmed the formation of elongated spherical shaped HA NPs with an average particle size of about 34 nm. The HA NPs thin film on glassy carbon electrode (GCE) were deposited by drop casting method. Electrocatalytic behavior of FA in the physiological pH 7.0 was investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry. The fabricated HA/GCE exhibited a linear calibration plot over a wide FA concentration ranging from 1.0 × 10-7 to 3.5 × 10-4 M with the detection limit of 75 nM. In addition, the HA NPs modified GCE showed good selectivity toward the determination of FA even in the presence of a 100-fold excess of ascorbic acid (AA) and 1000-fold excess of other common interferents. The fabricated biosensor exhibits good sensitivity and stability, and was successfully applied for the determination of FA in pharmaceutical samples.

Aggregation-induced emission of 1,8-naphthalimide-casein micelle: investigation by synchronous spectrographic method.

PubMed

Sun, Yang; Liang, Xuhua; Zhao, Yingyong; Fan, Jun

2013-09-01

A novel 1,8-naphthalimide probe 1, bearing two acetic-acid moieties was synthesized. The acetic-acid groups, docked into the sub-domains of casein micelle and bound with tryptophan residues, and the 1,8-naphthalimide chromophore adsorbed on the surface of casein micelle, forming a supermolecule, 1-casein micelle, which exhibited the aggregation-induced synchronous emission (AISE) characters. The effect of pH on the intensity of supermolecule was investigated, and the result indicated that the emission enhancement was mainly due to the 1,8-naphthalimide chromophore aggregated onto the casein micelle. Based on AISE, a novel casein quantification method was developed, which exhibited a good linear range of 0.05-10.0 μg ml(-1) and 0.07-9.5 μg ml(-1) with the detection limits of 2.8 and 3.0 ng ml(-1) . The effects of metal ions and pH on the system of 1-casein micelle were investigated. The proposed method was applied to determine casein in milk samples, and the results were in good agreement with the result of the Biuret method. Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.

A sensitive acetylcholinesterase biosensor based on gold nanorods modified electrode for detection of organophosphate pesticide.

PubMed

Lang, Qiaolin; Han, Lei; Hou, Chuantao; Wang, Fei; Liu, Aihua

2016-08-15

A sensitive amperometric acetylcholinesterase (AChE) biosensor, based on gold nanorods (AuNRs), was developed for the detection of organophosphate pesticide. Compared with Au@Ag heterogeneous NRs, AuNRs exhibited excellent electrocatalytic properties, which can electrocatalytically oxidize thiocholine, the hydrolysate of acetylthiocholine chloride (ATCl) by AChE at +0.55V (vs. SCE). The AChE/AuNRs/GCE biosensor was fabricated on basis of the inhibition of AChE activity by organophosphate pesticide. The biosensor could detect paraoxon in the linear range from 1nM to 5μM and dimethoate in the linear range from 5nM to 1μM, respectively. The detection limits of paraoxon and dimethoate were 0.7nM and 3.9nM, which were lower than the reported AChE biosensor. The proposed biosensor could restore to over 95% of its original current, which demonstrated the good reactivation. Moreover, the biosensor can be applicable to real water sample measurement. Thus, the biosensor exhibited low applied potential, high sensitivity and good stability, providing a promising tool for analysis of pesticides. Copyright © 2016 Elsevier B.V. All rights reserved.

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

He Liang; Xiu Faxian; Huang Guan

In this paper, we report the epitaxial growth of Bi{sub 2}Se{sub 3} thin films on Si (111) substrate, using molecular beam epitaxy (MBE). We show that the as-grown samples have good crystalline quality, and their surfaces exhibit terracelike quintuple layers. Angel-resolved photoemission experiments demonstrate single-Dirac-conelike surface states. These results combined with the temperature- and thickness-dependent magneto-transport measurements, suggest the presence of a shallow impurity band. Below a critical temperature of {approx}100K, the surface states of a 7 nm thick film contribute up to 50% of the total conduction.

Effect of whey protein isolate and β-cyclodextrin wall systems on stability of microencapsulated vanillin by spray-freeze drying method.

PubMed

Hundre, Swetank Y; Karthik, P; Anandharamakrishnan, C

2015-05-01

Vanillin flavour is highly volatile in nature and due to that application in food incorporation is limited; hence microencapsulation of vanillin is an ideal technique to increase its stability and functionality. In this study, vanillin was microencapsulated for the first time by non-thermal spray-freeze-drying (SFD) technique and its stability was compared with other conventional techniques such as spray drying (SD) and freeze-drying (FD). Different wall materials like β-cyclodextrin (β-cyd), whey protein isolate (WPI) and combinations of these wall materials (β-cyd + WPI) were used to encapsulate vanillin. SFD microencapsulated vanillin with WPI showed spherical shape with numerous fine pores on the surface, which in turn exhibited good rehydration ability. On the other hand, SD powder depicted spherical shape without pores and FD encapsulated powder yielded larger particle sizes with flaky structure. FTIR analysis confirmed that there was no interaction between vanillin and wall materials. Moreover, spray-freeze-dried vanillin + WPI sample exhibited better thermal stability than spray dried and freeze-dried microencapsulated samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Thermoplastic deformation of ferromagnetic CoFe-based bulk metallic glasses

NASA Astrophysics Data System (ADS)

Wu, Chenguang; Hu, Renchao; Man, Qikui; Chang, Chuntao; Wang, Xinmin

2017-12-01

The superplastic deformation behavior of the ferromagnetic Co31Fe31Nb8B30 bulk metallic glass (BMG) in the supercooled liquid region was investigated. At a given temperature, the BMG exhibits a Newtonian behavior at low strain rates but a non-Newtonian behavior at high strain rates. The high thermal stability of this glassy alloy system offers an enough processing window to thermoplastic forming (TPF), and the strong processing ability was examined by simple micro-replication experiments. It is demonstrated that the TPF formability on length scales ranging down to nanometers can be achieved in the selected experimental condition. Based on the analysis of deformation behavior, the nearly full density sample (i.e. nearly 100%), was produced from water-atomized glassy powders and consolidated by the hot-pressing technique. The sample exhibits good soft-magnetic and mechanical properties, i.e., low coercive force of 0.43 Oe, high initial permeability of 4100 and high Vickers hardness 1398. These results suggest that the hot-pressing process opens up possibilities for the commercial exploitation of BMGs in engineering applications.

Bioactive Glasses with Low Ca/P Ratio and Enhanced Bioactivity

PubMed Central

Araújo, Marco; Miola, Marta; Baldi, Giovanni; Perez, Javier; Verné, Enrica

2016-01-01

Three new silica-based glass formulations with low molar Ca/P ratio (2–3) have been synthesized. The thermal properties, the crystalline phases induced by thermal treatments and the sintering ability of each glass formulation have been investigated by simultaneous differential scanning calorimetry-thermogravimetric analysis (DSC-TG), X-ray diffraction (XRD) and hot stage microscopy (HSM). The glasses exhibited a good sintering behavior, with two samples achieving shrinkage of 85%–95% prior to crystallization. The bioactivity of the glasses in simulated body fluid (SBF) has been investigated by performing XRD and Fourier transform infrared spectroscopy (FTIR) on the samples prior and after immersion. The glasses with lower MgO contents were able to form a fully crystallized apatite layer after three days of immersion in simulated body fluid (SBF), while for the glass exhibiting a higher MgO content in its composition, the crystallization of the Ca–P layer was achieved after seven days. The conjugation of these properties opens new insights on the synthesis of highly bioactive and mechanically strong prosthetic materials. PMID:28773350

Zn-Ge-Sb glass composite mixed with Ba2+ ions: a high capacity anode material for Na-ion batteries

NASA Astrophysics Data System (ADS)

Ravuri, Balaji Rao; Gandi, Suman; Chinta, Srinivasa Rao

2018-06-01

(100-x)(0.7[0.625ZnO-0.375GeO2]-0.3Sb2O3)-xBaO (x = 0, 2, 4 and 6 mol%, labeled as ZGSB x ) glass anode samples are synthesized using a high-energy ball-milling method and employed as anode material for Na-ion batteries. The results on microstructures (XRD, SEM) and electrochemical properties (constant current charge/discharge tests, CV and EIS) indicated that the optimum concentration of Ba2+ ions in the Zn-Ge-Sb glass anode network exhibits the pillaring effect, which would lead to increased electrical conductivity, minimize the volume changes, cracks and voids to boost up electrochemical performance. The ZGSB4 glass anode sample exhibits good capacity retention even after 20 cycles with 95% coulombic efficiency, which is a significant trend for a successful anode network. Electrochemical performance is considerably enhanced by reducing the cut-off voltage from 2 to 1.25 V due to the disassembly of amorphous intermediate domains, optimum volume changes and increased electrical conductivity in this ZGSB x glass network.

Self-Healable and Reprocessable Polysulfide Sealants Prepared from Liquid Polysulfide Oligomer and Epoxy Resin.

PubMed

Gao, Wentong; Bie, Mengyao; Liu, Fu; Chang, Pengshan; Quan, Yiwu

2017-05-10

Polysulfide sealants have been commercially applied in many industrial fields. In this article, we study the self-healing property of the epoxy resin-cured polysulfide sealants for the first time. The obtained sealants showed a flexible range of ultimate elongation of 157-478% and a tensile strength of 1.02-0.75 MPa corresponding to different polysulfide oligomers. By taking advantage of the dynamic reversible exchange of disulfide bonds, polysulfide sealants exhibited good self-healing ability under a moderate thermal stimulus. A higher molecular weight and a lower degree of cross-linking of polysulfide oligomer were helpful in improving the ultimate elongation and healing efficiency of the polysulfide sealants. After subjecting to a temperature of 75 °C for 60 min, both the tensile strength and ultimate elongation of a fully cut sample, LP55-F, were restored to 91% of the original values, without affecting the sealing property. Furthermore, the sample exhibited excellent reshaping and reprocessing abilities. These outcomes offer a paradigm toward sustainable industrial applications of the polysulfide-based sealants.

Combination of QuEChERS and DLLME for GC-MS determination of pesticide residues in orange samples.

PubMed

Andraščíková, Mária; Hrouzková, Svetlana; Cunha, Sara C

2013-01-01

A new method combining QuEChERS (quick, easy, cheap, effective, rugged and safe) and DLLME (dispersive liquid-liquid microextraction) followed by gas chromatography-mass spectrometry with selected ion monitoring (SIM) was developed for the simultaneous determination of 19 pesticides from nine chemical groups exhibiting or suspected to exhibit endocrine-disrupting properties in orange samples. Acetonitrile extract obtained from QuEChERS extraction was used for DLLME as dispersive solvent and carbon tetrachloride as extractive solvent to increase the enrichment factor of the extraction procedure. The effect of several extraction parameters, such as volume extract achieved by the QuEChERS method and subsequently used for DLLME, selection of extractive solvent and its volume, was tested. Under optimum conditions, good linearity, satisfactory recoveries and repeatability were obtained. Limits of quantification (LOQs) achieved (ranging from 0.02 to 47 ng/g) were below the maximum residue limits established by the European Union. The proposed method was applied to the monitoring of pesticide residue levels in oranges commercialised in Portugal.

Polarization Stability of Amorphous Piezoelectric Polyimides

NASA Technical Reports Server (NTRS)

Park, C.; Ounaies, Z.; Su, J.; Smith, J. G., Jr.; Harrison, J. S.

2000-01-01

Amorphous polyimides containing polar functional groups have been synthesized and investigated for potential use as high temperature piezoelectric sensors. The thermal stability of the piezoelectric effect of one polyimide was evaluated as a function of various curing and poling conditions under dynamic and static thermal stimuli. First, the polymer samples were thermally cycled under strain by systematically increasing the maximum temperature from 50 C to 200 C while the piezoelectric strain coefficient was being measured. Second, the samples were isothermally aged at an elevated temperature in air, and the isothermal decay of the remanent polarization was measured at room temperature as a function of time. Both conventional and corona poling methods were evaluated. This material exhibited good thermal stability of the piezoelectric properties up to 100 C.

Computerized cognitive training in survivors of childhood cancer: a pilot study.

PubMed

Hardy, Kristina K; Willard, Victoria W; Bonner, Melanie J

2011-01-01

The objective of the current study was to pilot a computerized cognitive training program, Captain's Log, in a small sample of survivors of childhood cancer. A total of 9 survivors of acute lymphoblastic leukemia and brain tumors with attention and working memory deficits were enrolled in a home-based 12-week cognitive training program. Survivors returned for follow-up assessments postintervention and 3 months later. The intervention was associated with good feasibility and acceptability. Participants exhibited significant increases in working memory and decreases in parent-rated attention problems following the intervention. Findings indicate that home-based, computerized cognitive intervention is a promising intervention for survivors with cognitive late effects; however, further study is warranted with a larger sample.

Controllable synthesis of MnO2/polyaniline nanocomposite and its electrochemical capacitive property

PubMed Central

2013-01-01

Polyaniline (PANI) and MnO2/PANI composites are simply fabricated by one-step interfacial polymerization. The morphologies and components of MnO2/PANI composites are modulated by changing the pH of the solution. Formation procedure and capacitive property of the products are investigated by XRD, FTIR, TEM, and electrochemical techniques. We demonstrate that MnO2 as an intermedia material plays a key role in the formation of sample structures. The MnO2/PANI composites exhibit good cycling stability as well as a high capacitance close to 207 F g−1. Samples fabricated with the facile one-step method are also expected to be adopted in other field such as catalysis, lithium ion battery, and biosensor. PMID:23594724

Controllable synthesis of MnO2/polyaniline nanocomposite and its electrochemical capacitive property

NASA Astrophysics Data System (ADS)

Meng, Fanhui; Yan, Xiuling; Zhu, Ye; Si, Pengchao

2013-04-01

Polyaniline (PANI) and MnO2/PANI composites are simply fabricated by one-step interfacial polymerization. The morphologies and components of MnO2/PANI composites are modulated by changing the pH of the solution. Formation procedure and capacitive property of the products are investigated by XRD, FTIR, TEM, and electrochemical techniques. We demonstrate that MnO2 as an intermedia material plays a key role in the formation of sample structures. The MnO2/PANI composites exhibit good cycling stability as well as a high capacitance close to 207 F g-1. Samples fabricated with the facile one-step method are also expected to be adopted in other field such as catalysis, lithium ion battery, and biosensor.

Oral microbiota carriage in patients with multibracket appliance in relation to the quality of oral hygiene.

PubMed

Klaus, Katharina; Eichenauer, Johanna; Sprenger, Rhea; Ruf, Sabine

2016-10-28

The present study aimed to investigate the prevalence of oral microbiota (Candida species (spp.), Streptococcus mutans, and Lactobacilli) in patients with multibracket (MB) appliances in relation to the quality of oral hygiene. Saliva and plaque samples were collected from three groups of 25 patients each (good oral hygiene (GOH), poor oral hygiene (POH), and poor oral hygiene with white spot lesions (POH/WSL)). Counts of colony forming units (CFU) of the investigated oral microbiota were compared using Chi-square and Mann-Whitney U tests. Both saliva and plaque samples showed a high prevalence of Candida spp. in all patients (saliva: 73.4 %, plaque: 60.9 %). The main Candida species was C. albicans. The salivary CFU of Candida spp. in the GOH group was significantly lower than that in the POH group (p = 0.045) and POH/WSL group (p = 0.011). S. mutans was found in the saliva and plaque samples of all patients. Lactobacilli were found in the saliva samples of all patients and in 90.7 % of the plaque samples. In the saliva samples, the CFU of Lactobacilli were more numerous in the POH and POH/WSL groups than in the GOH group (p = 0.047). The investigated sample of patients showed a high carriage of oral Candida spp. Patients with WSL formation during MB appliance treatment exhibited higher counts of Candida and Lactobacilli compared with patients with good oral hygiene. Independent of oral hygiene quality, S. mutans was detected in all patients.

Piezoelectric Properties of LiSbO3-Modified (K0.48Na0.52)NbO3 Lead-Free Ceramics

NASA Astrophysics Data System (ADS)

Wu, Jiagang; Wang, Yuanyu; Xiao, Dingquan; Zhu, Jianguo; Yu, Ping; Wu, Lang; Wu, Wenjuan

2007-11-01

Lead-free piezoelectric (1-x)(K0.48Na0.52)NbO3-xLiSbO3 [(1-x)KNN-xLS] ceramics were prepared by conventional sintering. A morphotropic phase boundary (MPB) between the orthorhombic and tetragonal phases was identified in the composition range of 0.04

Preparation and application of in-fibre internal standardization solid-phase microextraction.

PubMed

Zhao, Wennan; Ouyang, Gangfeng; Pawliszyn, Janusz

2007-03-01

The in-fibre standardization method is a novel approach that has been developed for field sampling/sample preparation, in which an internal standard is pre-loaded onto a solid-phase microextraction (SPME) fibre for calibration of the extraction of target analytes in field samples. The same method can also be used for in-vial sample analysis. In this study, different techniques to load the standard to a non-porous SPME fibre were investigated. It was found that the appropriateness of the technique depends on the physical properties of the standards that are used for the analysis. Headspace extraction of the standard dissolved in pumping oil works well for volatile compounds. Conversely, headspace extraction of the pure standard is an effective approach for semi-volatile compounds. For compounds with low volatility, a syringe-fibre transfer method and direct extraction of the standard dissolved in a solvent exhibited a good reproducibility (<5% RSD). The main advantage of the approaches investigated in this study is that the standard generation vials can be reused for hundreds of analyses without exhibiting significant loss. Moreover, most of the standard loading processes studied can be performed automatically, which is efficient and precise. Finally, the standard loading technique and in-fibre standardization method were applied to a complex matrix (milk) and the results illustrated that the matrix effect can be effectively compensated for with this approach.

A comparative study of the physicochemical properties of a virgin coconut oil emulsion and commercial food supplement emulsions.

PubMed

Khor, Yih Phing; Koh, Soo Peng; Long, Kamariah; Long, Shariah; Ahmad, Sharifah Zarah Syed; Tan, Chin Ping

2014-07-01

Food manufacturers are interested in developing emulsion-based products into nutritional foods by using beneficial oils, such as fish oil and virgin coconut oil (VCO). In this study, the physicochemical properties of a VCO oil-in-water emulsion was investigated and compared to other commercial oil-in-water emulsion products (C1, C2, C3, and C4). C3 exhibited the smallest droplet size of 3.25 µm. The pH for the emulsion samples ranged from 2.52 to 4.38 and thus were categorised as acidic. In a texture analysis, C2 was described as the most firm, very adhesive and cohesive, as well as having high compressibility properties. From a rheological viewpoint, all the emulsion samples exhibited non-Newtonian behaviour, which manifested as a shear-thinning property. The G'G'' crossover illustrated by the VCO emulsion in the amplitude sweep graph but not the other commercial samples illustrated that the VCO emulsion had a better mouthfeel. In this context, the VCO emulsion yielded the highest zeta potential (64.86 mV), which was attributed to its strong repulsive forces, leading to a good dispersion system. C2 comprised the highest percentage of fat among all emulsion samples, followed by the VCO emulsion, with 18.44% and 6.59%, respectively.

Separation and screening of short-chain chlorinated paraffins in environmental samples using comprehensive two-dimensional gas chromatography with micro electron capture detection.

PubMed

Xia, Dan; Gao, Lirong; Zhu, Shuai; Zheng, Minghui

2014-11-01

Short-chain chlorinated paraffins (SCCPs) are highly complex technical mixtures with thousands of isomers and numerous homologs. They are classified as priority candidate persistent organic pollutants under the Stockholm Convention for their persistence, bioaccumulation, and toxicity. Analyzing SCCPs is challenging because of the complexity of the mixtures. Chromatograms of SCCPs acquired using one-dimensional (1D) gas chromatography (GC) contain a large characteristic "peak" with a broad and unresolved profile. Comprehensive two-dimensional GC (GC×GC) shows excellent potential for separating complex mixtures. In this study, GC×GC coupled with micro electron capture detection (μECD) was used to separate and screen SCCPs. The chromatographic parameters, including the GC column types, oven temperature program, and modulation period, were systematically optimized. The SCCP congeners were separated into groups using a DM-1 column connected to a BPX-50 column. The SCCP congeners in technical mixtures were separated according to the number of chlorine substituents for a given carbon chain length and according to the number of carbon atoms plus chlorine atoms for different carbon chain lengths. A fish tissue sample was analyzed to illustrate the feasibility of the GC×GC-μECD method in analyzing biological samples. Over 1,500 compounds were identified in the fish extract, significantly more than were identified using 1D GC. The detection limits for five selected SCCP congeners were between 1 and 5 pg/L using the GC×GC method, and these were significantly lower than those achieved using 1D GC. This method is a good choice for analysis of SCCPs in environmental samples, exhibiting good separation and good sensitivity.

The Effect of Nano Loading and Ultrasonic Compounding of EVA/LDPE/Nano-magnesium Hydroxide on Mechanical Properties and Distribution of Nano Particles

NASA Astrophysics Data System (ADS)

Azman, I. A.; Salleh, R. M.; Alauddin, S. M.; Shueb, M. I.

2018-05-01

Blends of Ethylene Vinyl Acetate (EVA) and Low-Density Polyethylene (LDPE) are promising composite which have good mechanical properties to environmental stress cracking. However, they lack fire resistant properties, which limits it usage in wire and cable industry. In order to improve flame retardancy ability, a range of nano-magnesium hydroxide (nano-MH) loading which is from 0 phr to maximum of 20 phr with ultrasonic extrusion 0-100 kHz frequencies have been introduced. Ultrasonic extrusion was used to improve the distribution of nano-MH. It was found that, 10 phr of nano loading with 100 kHz ultrasonic assisted has greater tensile strength compared to the nanocomposite without ultrasonication. Further increase of nano MH loading, will decrease the tensile properties. Better elongation at break was observed at10 phr nano-MH with the frequency of 50 kHz. The sample of 20 phr of nanoMH assisted with 50 kHz ultrasonic exhibits good flexural properties while 10 phr of nano-MH without the ultrasonic assisted demonstrates good in izod impact properties. From the evaluation of mechanical properties studied, it was found that 10 phr of nano-MH has shown the best performance among all the samples tested for EVA/LDPE/nano-MH composites. Transmission Electron Microscopy (TEM) has been conducted on 10 phr sample with different frequencies in order to observe the distribution of nano-MH particles. The sample with 100 kHz frequency shows more uniform dispersion of nano-MH in EVA/LDPE composites. This investigation indicates that the ultrasonic technology can enhance the mechanical properties studied as well as the dispersion of nano particles in the composite.

Free-standing anode of N-doped carbon nanofibers containing SnO{sub x} for high-performance lithium batteries

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

Zou, Mingzhong; Li, Jiaxin, E-mail: ljx3012982@yahoo.com; Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002

2014-12-15

Highlights: • Self-standing SnO{sub x} N-CNF electrodes were synthesized by electrospinning. • The SnO{sub x} N-CNFs anode exhibits high capacity, good cyclic stability, and excellent rate performance for lithium ion batteries. • The enhanced performance is ascribed to the synergetic effects between N-CNFs and SnO{sub x} nanoparticles. - Abstract: Free-standing paper of N-doped carbon nanofibers (NCNFs) containing SnO{sub x} was prepared by electrospinning. The structure and morphology of the sample were analyzed by XRD, XPS, SEM, and TEM. The results show that nitrogen atoms were successfully doped into CNFs. The SnO{sub x} were homogenously embedded in the N-doped CNFs viamore » annealing treatment. Subsequently, the SnO{sub x} NCNF paper was cut into disks and used as anodes for lithium ion batteries (LIBs). The anodes of SnO{sub x} NCNFs exhibit excellent cycling stability and show high capacity of 520 mA h g{sup −1} tested at a 200 mA g{sup −1} after 100 cycles. More importantly, at a high current density of 500 mA g{sup −1}, a large reversible capacity of 430 mA h g{sup −1} after 100 cycles can still be obtained. The good electrochemical performance should be attributed to the good electronic conductivity from the NCNFs and the synergistic effects from NCNFs and SnO{sub x} materials.« less

A microfluidic paper-based analytical device for the assay of albumin-corrected fructosamine values from whole blood samples.

PubMed

Boonyasit, Yuwadee; Laiwattanapaisal, Wanida

2015-01-01

A method for acquiring albumin-corrected fructosamine values from whole blood using a microfluidic paper-based analytical system that offers substantial improvement over previous methods is proposed. The time required to quantify both serum albumin and fructosamine is shortened to 10 min with detection limits of 0.50 g dl(-1) and 0.58 mM, respectively (S/N = 3). The proposed system also exhibited good within-run and run-to-run reproducibility. The results of the interference study revealed that the acceptable recoveries ranged from 95.1 to 106.2%. The system was compared with currently used large-scale methods (n = 15), and the results demonstrated good agreement among the techniques. The microfluidic paper-based system has the potential to continuously monitor glycemic levels in low resource settings.

Cross-sectional survey of Good Samaritan behaviour by physicians in North Carolina

PubMed Central

Garneau, William M; Harris, Dean M; Viera, Anthony J

2016-01-01

Objective To assess the responses of physicians to providing emergency medical assistance outside of routine clinical care. We assessed the percentage who reported previous Good Samaritan behaviour, their responses to hypothetical situations, their comfort providing specific interventions and the most likely reason they would not intervene. Setting Physicians residing in North Carolina. Participants Convenience sample of 1000 licensed physicians. Intervention Mailed survey. Design Cross-sectional study conducted May 2015 to September 2015. Main outcome and measures Willingness of physicians to act as Good Samaritans as determined by the last opportunity to intervene in an out-of-office emergency. Results The adjusted response rate was 26.1% (253/970 delivered). 4 out of 5 physicians reported previous opportunities to act as Good Samaritans. Approximately, 93% reported acting as a Good Samaritan during their last opportunity. There were no differences in this outcome between sexes, practice setting, specialty type or experience level. Doctors with greater perceived knowledge of Good Samaritan law were more likely to have intervened during a recent opportunity (p=0.02). The most commonly cited reason for potentially not intervening was that another health provider had taken charge. Conclusions We found the frequency of Good Samaritan behaviour among physicians to be much higher than reported in previous studies. Greater helping behaviour was exhibited by those who expressed more familiarity with Good Samaritan law. These findings suggest that physicians may respond to legal protections. PMID:26966061

Physiological indices of seawater readiness in postspawning steelhead kelts

USGS Publications Warehouse

Buelow, Jessica; Moffitt, Christine M.

2015-01-01

Management goals to improve the recovery of steelhead (Oncorhynchus mykiss) stocks at risk of extinction include increasing the proportion of postspawning fish that survive and spawn again. To be successful, postspawning steelhead (kelts) migrating downstream to the ocean must prepare physiologically and physically for a seawater transition. We sampled blood, gill filaments, and evaluated the external condition of migrating kelts from an ESA-listed population in the Snake/Columbia River system over two consecutive years to evaluate their physiological readiness for transition to seawater. We chose attributes often considered as measures of preparation for seawater in juveniles, including gill Na+,K+ ATPase activity, plasma electrolytes and hormones to consider factors related to external condition, size and sex. We found kelts in good external condition had plasma profiles similar to downstream-migrating smolts. In addition, we found more than 80% of kelts ranked in good external condition had smolt-like body silvering. We compared measures from migrating kelts with samples obtained from hatchery fish at the time of spawning to confirm that Na+, K+ ATPase activity in kelts was significantly elevated over spawning fish. We found significant differences in gill Na+, K+ ATPase activity in migrating kelts between the years of sampling, but little indication of influence of fish condition. We conclude that the postspawning steelhead sampled exhibited a suite of behaviours, condition and physiology characteristic of fish prepared for successful transition to a seawater environment.

Antioxidant and antimicrobial properties of polyphenolic fractions from selected Moroccan red wines.

PubMed

Tenore, Gian Carlo; Basile, Adriana; Novellino, Ettore

2011-01-01

The present study is the first effort to a comprehensive evaluation of the antioxidant and antimicrobial activities of fractionated red wines from Morocco. The results obtained revealed that the wine samples were characterized by a higher phytochemical concentration than the same variety of wines with a different geographical origin and other more consumed red wines, confirming what was reported in a previous authors' work. The most phenolic-rich fractions were the ones containing phenolic acids and quercetin glucoronides from Syrah and Merlot wine samples while Cabernet Sauvignon exhibited the highest monomeric anthocyanin content. The antioxidant activity of wine extracts was tested by ferric reducing antioxidant power and 1,1-diphenyl-2-picrilhydrazyl assays. Samples revealed a higher reducing capacity than radical scavenging property and a good correlation between antioxidant activity and polyphenolic content values. As regards the antimicrobial properties, each fraction exhibited activity against a broad spectrum of food-borne microorganisms, revealing not only a moderate to high natural preserving capacity, but also potentially beneficial influence on human health. In consideration of the scarcity of data regarding composition and biological properties of Moroccan red wines, the present study may represent a valuable reference for wine consumers and producers. © 2011 Institute of Food Technologists®

A Spectroscopic Survey of Redshift 1.4<~z<~3.0 Galaxies in the GOODS-North Field: Survey Description, Catalogs, and Properties

NASA Astrophysics Data System (ADS)

Reddy, Naveen A.; Steidel, Charles C.; Erb, Dawn K.; Shapley, Alice E.; Pettini, Max

2006-12-01

We present the results of a spectroscopic survey with LRIS-B on Keck of more than 280 star-forming galaxies and AGNs at redshifts 1.4<~z<~3.0 in the GOODS-N field. Candidates are selected by their UnGR colors using the ``BM/BX'' criteria to target redshift 1.4<~z<~2.5 galaxies and the LBG criteria to target redshift z~3 galaxies; combined these samples account for ~25%-30% of the R and Ks band counts to R=25.5 and Ks(AB)=24.4, respectively. The 212 BM/BX galaxies and 74 LBGs constitute the largest spectroscopic sample of galaxies at z>1.4 in GOODS-N. Extensive multiwavelength data allow us to investigate the stellar populations, stellar masses, bolometric luminosities (Lbol), and extinction of z~2 galaxies. Deep Chandra and Spitzer data indicate that the sample includes galaxies with a wide range in Lbol (~=1010 to >1012 Lsolar) and 4 orders of magnitude in dust obscuration (Lbol/LUV). The sample includes galaxies with a large dynamic range in evolutionary state, from very young galaxies (ages ~=50 Myr) with small stellar masses (M*~=109 Msolar) to evolved galaxies with stellar masses comparable to the most massive galaxies at these redshifts (M*>1011 Msolar). Spitzer data indicate that the optical sample includes some fraction of the obscured AGN population at high redshifts: at least 3 of 11 AGNs in the z>1.4 sample are undetected in the deep X-ray data but exhibit power-law SEDs longward of ~2 μm (rest frame) indicative of obscured AGNs. The results of our survey indicate that rest-frame UV selection and spectroscopy presently constitute the most timewise efficient method of culling large samples of high-redshift galaxies with a wide range in intrinsic properties, and the data presented here will add significantly to the multiwavelength legacy of GOODS. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA and was made possible by the generous financial support of the W. M. Keck Foundation.

Subcritical water extraction of alkaloids in Sophora flavescens Ait. and determination by capillary electrophoresis with field-amplified sample stacking.

PubMed

Wang, Haiyan; Lu, Yuchao; Chen, Jie; Li, Junchao; Liu, Shuhui

2012-01-25

The extraction and determination of cytisine, sophocarpine, matrine, sophoridine and oxymatrine in Sophora flavescens Ait. were performed using subcritical water extraction and capillary electrophoresis with field-amplified sample stacking. The effects of extraction temperature, pressure, time and cycle number on the extraction yields were investigated systematically for accelerated solvent extraction with ethanol (ASE) and accelerated solvent extraction with water (subcritical water extraction, SWE). The extraction yields obtained using SWE, ASE, water ultrasonic extraction and chloroform soaking extraction methods were compared. The electrophoresis separation buffer was monosodium phosphate (pH 3.0; 110 mM)-isopropanol (85:15, v/v). The effect of phosphoric acid added to the sample matrix on the reproducibility of the peak heights of the analytes was also examined. Cytisine, sophoridine and oxymatrine showed good linearity (R(2)>0.999) within 0.125-4.0 μg/mL, and sophocarpine and matrine exhibited good linearity (R(2)>0.998) within 0.0625-2.0 μg/mL, with the detection limits in the range of 0.004-0.0013 μg/mL. The five alkaloid contents in medicinal plants from different sources and Sophora instant granule were determined and compared. Copyright © 2011 Elsevier B.V. All rights reserved.

Structural parameterization and functional prediction of antigenic polypeptome sequences with biological activity through quantitative sequence-activity models (QSAM) by molecular electronegativity edge-distance vector (VMED).

PubMed

Li, ZhiLiang; Wu, ShiRong; Chen, ZeCong; Ye, Nancy; Yang, ShengXi; Liao, ChunYang; Zhang, MengJun; Yang, Li; Mei, Hu; Yang, Yan; Zhao, Na; Zhou, Yuan; Zhou, Ping; Xiong, Qing; Xu, Hong; Liu, ShuShen; Ling, ZiHua; Chen, Gang; Li, GenRong

2007-10-01

Only from the primary structures of peptides, a new set of descriptors called the molecular electronegativity edge-distance vector (VMED) was proposed and applied to describing and characterizing the molecular structures of oligopeptides and polypeptides, based on the electronegativity of each atom or electronic charge index (ECI) of atomic clusters and the bonding distance between atom-pairs. Here, the molecular structures of antigenic polypeptides were well expressed in order to propose the automated technique for the computerized identification of helper T lymphocyte (Th) epitopes. Furthermore, a modified MED vector was proposed from the primary structures of polypeptides, based on the ECI and the relative bonding distance of the fundamental skeleton groups. The side-chains of each amino acid were here treated as a pseudo-atom. The developed VMED was easy to calculate and able to work. Some quantitative model was established for 28 immunogenic or antigenic polypeptides (AGPP) with 14 (1-14) A(d) and 14 other restricted activities assigned as "1"(+) and "0"(-), respectively. The latter comprised 6 A(b)(15-20), 3 A(k)(21-23), 2 E(k)(24-26), 2 H-2(k)(27 and 28) restricted sequences. Good results were obtained with 90% correct classification (only 2 wrong ones for 20 training samples) and 100% correct prediction (none wrong for 8 testing samples); while contrastively 100% correct classification (none wrong for 20 training samples) and 88% correct classification (1 wrong for 8 testing samples). Both stochastic samplings and cross validations were performed to demonstrate good performance. The described method may also be suitable for estimation and prediction of classes I and II for major histocompatibility antigen (MHC) epitope of human. It will be useful in immune identification and recognition of proteins and genes and in the design and development of subunit vaccines. Several quantitative structure activity relationship (QSAR) models were developed for various oligopeptides and polypeptides including 58 dipeptides and 31 pentapeptides with angiotensin converting enzyme (ACE) inhibition by multiple linear regression (MLR) method. In order to explain the ability to characterize molecular structure of polypeptides, a molecular modeling investigation on QSAR was performed for functional prediction of polypeptide sequences with antigenic activity and heptapeptide sequences with tachykinin activity through quantitative sequence-activity models (QSAMs) by the molecular electronegativity edge-distance vector (VMED). The results showed that VMED exhibited both excellent structural selectivity and good activity prediction. Moreover, the results showed that VMED behaved quite well for both QSAR and QSAM of poly-and oligopeptides, which exhibited both good estimation ability and prediction power, equal to or better than those reported in the previous references. Finally, a preliminary conclusion was drawn: both classical and modified MED vectors were very useful structural descriptors. Some suggestions were proposed for further studies on QSAR/QSAM of proteins in various fields.

Influence of the pore fluid on the phase velocity in bovine trabecular bone In Vitro: Prediction of the biot model

NASA Astrophysics Data System (ADS)

Lee, Kang Il

2013-01-01

The present study aims to investigate the influence of the pore fluid on the phase velocity in bovine trabecular bone in vitro. The frequency-dependent phase velocity was measured in 20 marrow-filled and water-filled bovine femoral trabecular bone samples. The mean phase velocities at frequencies between 0.6 and 1.2 MHz exhibited significant negative dispersions for both the marrow-filled and the water-filled samples. The magnitudes of the dispersions showed no significant differences between the marrow-filled and the water-filled samples. In contrast, replacement of marrow by water led to a mean increase in the phase velocity of 27 m/s at frequencies from 0.6 to 1.2 MHz. The theoretical phase velocities of the fast wave predicted by using the Biot model for elastic wave propagation in fluid-saturated porous media showed good agreements with the measurements.

Oxidation behavior of a ferritic stainless steel Crofer22 APU with thermal cycling

NASA Astrophysics Data System (ADS)

Song, MyoungYoup; Duong, Anh T.; Mumm, Daniel R.

2013-01-01

Crofer22 APU specimens were prepared by grinding with grit 80 and 120 SiC grinding papers and were thermally cycled. The variation in oxidation behavior with thermal cycling was then investigated. Observation of microstructure, measurement of area specific resistance (ASR), analysis of the atomic percentages of the elements by EDX, and XRD analysis were performed. XRD patterns showed that the (Cr, Mn)3O4 spinel phase grew on the surface of the Crofer22 APU samples ground with grit 120. For the samples ground with grit 80, the ASR increased as the number of thermal cycles increased. Plots of ln (ASR/T) vs. 1/T for the samples ground with grit 80 after n = 4, 20 and 40 exhibited good linearity, and the apparent activation energies were between 63.7 kJ/mole and 76.3 kJ/mole.

Variation with thermal cycling in microstructure and area specific resistance of a ferritic stainless steel having rough surfaces

NASA Astrophysics Data System (ADS)

Song, Myoung Youp; Mumm, Daniel R.; Song, Jiunn

2013-03-01

Crofer22 APU specimens were prepared by grinding with grit 120 and 400 SiC grinding papers, and were then thermally cycled. The variation in oxidation behavior with thermal cycling was then investigated. Observation of microstructures, measurement of area-specific resistance (ASR), analysis of the atomic percentages of the elements by EDX, and XRD analysis were performed. XRD patterns showed that the (Cr, Mn)3O4 spinel phase grew on the surface of the Crofer22 APU samples ground using grit 120. For the samples ground with grit 400, ASR increased as the number of thermal cycles ( n) increased. Plots of ln (ASR/T) vs. 1/ T for the samples ground with grit 400 after n = 4, 20, and 40 exhibited good linearity, and the apparent activation energies were between 73.4 kJ/mole and 82.5 kJ/mole.

Diagnostic accuracy of language sample measures with Persian-speaking preschool children.

PubMed

Kazemi, Yalda; Klee, Thomas; Stringer, Helen

2015-04-01

This study examined the diagnostic accuracy of selected language sample measures (LSMs) with Persian-speaking children. A pre-accuracy study followed by phase I and II studies are reported. Twenty-four Persian-speaking children, aged 42 to 54 months, with primary language impairment (PLI) were compared to 27 age-matched children without PLI on a set of measures derived from play-based, conversational language samples. Results showed that correlations between age and LSMs were not statistically significant in either group of children. However, a majority of LSMs differentiated children with and without PLI at the group level (phase I), while three of the measures exhibited good diagnostic accuracy at the level of the individual (phase II). We conclude that general LSMs are promising for distinguishing between children with and without PLI. Persian-specific measures are mainly helpful in identifying children without language impairment while their ability to identify children with PLI is poor.

A CuNi/C Nanosheet Array Based on a Metal-Organic Framework Derivate as a Supersensitive Non-Enzymatic Glucose Sensor

NASA Astrophysics Data System (ADS)

Zhang, Li; Ye, Chen; Li, Xu; Ding, Yaru; Liang, Hongbo; Zhao, Guangyu; Wang, Yan

2018-06-01

Bimetal catalysts are good alternatives for non-enzymatic glucose sensors owing to their low cost, high activity, good conductivity, and ease of fabrication. In the present study, a self-supported CuNi/C electrode prepared by electrodepositing Cu nanoparticles on a Ni-based metal-organic framework (MOF) derivate was used as a non-enzymatic glucose sensor. The porous construction and carbon scaffold inherited from the Ni-MOF guarantee good kinetics of the electrode process in electrochemical glucose detection. Furthermore, Cu nanoparticles disturb the array structure of MOF derived films and evidently enhance their electrochemical performances in glucose detection. Electrochemical measurements indicate that the CuNi/C electrode possesses a high sensitivity of 17.12 mA mM-1 cm-2, a low detection limit of 66.67 nM, and a wider linearity range from 0.20 to 2.72 mM. Additionally, the electrode exhibits good reusability, reproducibility, and stability, thereby catering to the practical use of glucose sensors. Similar values of glucose concentrations in human blood serum samples are detected with our electrode and with the method involving glucose-6-phosphate dehydrogenase; the results further demonstrate the practical feasibility of our electrode.

Magnetic signature of overbank sediment in industry impacted floodplains identified by data mining methods

NASA Astrophysics Data System (ADS)

Chudaničová, Monika; Hutchinson, Simon M.

2016-11-01

Our study attempts to identify a characteristic magnetic signature of overbank sediments exhibiting anthropogenically induced magnetic enhancement and thereby to distinguish them from unenhanced sediments with weak magnetic background values, using a novel approach based on data mining methods, thus providing a mean of rapid pollution determination. Data were obtained from 539 bulk samples from vertical profiles through overbank sediment, collected on seven rivers in the eastern Czech Republic and three rivers in northwest England. k-Means clustering and hierarchical clustering methods, paired group (UPGMA) and Ward's method, were used to divide the samples to natural groups according to their attributes. Interparametric ratios: SIRM/χ; SIRM/ARM; and S-0.1T were chosen as attributes for analyses making the resultant model more widely applicable as magnetic concentration values can differ by two orders. Division into three clusters appeared to be optimal and corresponded to inherent clusters in the data scatter. Clustering managed to separate samples with relatively weak anthropogenically induced enhancement, relatively strong anthropogenically induced enhancement and samples lacking enhancement. To describe the clusters explicitly and thus obtain a discrete magnetic signature, classification rules (JRip method) and decision trees (J4.8 and Simple Cart methods) were used. Samples lacking anthropogenic enhancement typically exhibited an S-0.1T < c. 0.5, SIRM/ARM < c. 150 and SIRM/χ < c. 6000 A m-1. Samples with magnetic enhancement all exhibited an S-0.1T > 0.5. Samples with relatively stronger anthropogenic enhancement were unequivocally distinguished from the samples with weaker enhancement by an SIRM/ARM > c. 150. Samples with SIRM/ARM in a range c. 126-150 were classified as relatively strongly enhanced when their SIRM/χ > 18 000 A m-1 and relatively less enhanced when their SIRM/χ < 18 000 A m-1. An additional rule was arbitrary added to exclude samples with χfd% > 6 per cent from anthropogenically enhanced clusters as samples with natural magnetic enhancement. The characteristics of the clusters resulted mainly from the relationship between SIRM/ARM and the S-0.1T, and SIRM/χ and the S-0.1T. Both SIRM/ARM and SIRM/χ increase with increasing S-0.1T values reflecting a greater level of anthropogenic magnetic particles. Overall, data mining methods demonstrated good potential for utilization in environmental magnetism.

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.

Molecularly imprinted membrane extraction combined with high-performance liquid chromatography for selective analysis of cloxacillin from shrimp samples.

PubMed

Du, Wei; Sun, Min; Guo, Pengqi; Chang, Chun; Fu, Qiang

2018-09-01

Nowadays, the abuse of antibiotics in aquaculture has generated considerable problems for food safety. Therefore, it is imperative to develop a simple and selective method for monitoring illegal use of antibiotics in aquatic products. In this study, a method combined molecularly imprinted membranes (MIMs) extraction and liquid chromatography was developed for the selective analysis of cloxacillin from shrimp samples. The MIMs was synthesized by UV photopolymerization, and characterized by scanning electron microscope, Fourier transform infrared spectra, thermo-gravimetric analysis and swelling test. The results showed that the MIMs exhibited excellent permselectivity, high adsorption capacity and fast adsorption rate for cloxacillin. Finally, the method was utilized to determine cloxacillin from shrimp samples, with good accuracies and acceptable relative standard deviation values for precision. The proposed method was a promising alternative for selective analysis of cloxacillin in shrimp samples, due to the easy-operation and excellent selectivity. Copyright © 2018. Published by Elsevier Ltd.

Lactoferrin-Immobilized Surfaces onto Functionalized PLA Assisted by the Gamma-Rays and Nitrogen Plasma to Create Materials with Multifunctional Properties.

PubMed

Stoleru, Elena; Zaharescu, Traian; Hitruc, Elena Gabriela; Vesel, Alenka; Ioanid, Emil G; Coroaba, Adina; Safrany, Agnes; Pricope, Gina; Lungu, Maria; Schick, Christoph; Vasile, Cornelia

2016-11-23

Both cold nitrogen radiofrequency plasma and gamma irradiation have been applied to activate and functionalize the polylactic acid (PLA) surface and the subsequent lactoferrin immobilization. Modified films were comparatively characterized with respect to the procedure of activation and also with unmodified sample by water contact angle measurements, mass loss, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), and chemiluminescence measurements. All modified samples exhibit enhanced surface properties mainly those concerning biocompatibility, antimicrobial, and antioxidant properties, and furthermore, they are biodegradable and environmentally friendly. Lactoferrin deposited layer by covalent coupling using carbodiimide chemistry showed a good stability. It was found that the lactoferrin-modified PLA materials present significantly increased oxidative stability. Gamma-irradiated samples and lactoferrin-functionalized samples show higher antioxidant, antimicrobial, and cell proliferation activity than plasma-activated and lactoferrin-functionalized ones. The multifunctional materials thus obtained could find application as biomaterials or as bioactive packaging films.

Mood states modulate complexity in heartbeat dynamics: A multiscale entropy analysis

NASA Astrophysics Data System (ADS)

Valenza, G.; Nardelli, M.; Bertschy, G.; Lanata, A.; Scilingo, E. P.

2014-07-01

This paper demonstrates that heartbeat complex dynamics is modulated by different pathological mental states. Multiscale entropy analysis was performed on R-R interval series gathered from the electrocardiogram of eight bipolar patients who exhibited mood states among depression, hypomania, and euthymia, i.e., good affective balance. Three different methodologies for the choice of the sample entropy radius value were also compared. We show that the complexity level can be used as a marker of mental states being able to discriminate among the three pathological mood states, suggesting to use heartbeat complexity as a more objective clinical biomarker for mental disorders.

Conductance switching in Ag(2)S devices fabricated by in situ sulfurization.

PubMed

Morales-Masis, M; van der Molen, S J; Fu, W T; Hesselberth, M B; van Ruitenbeek, J M

2009-03-04

We report a simple and reproducible method to fabricate switchable Ag(2)S devices. The alpha-Ag(2)S thin films are produced by a sulfurization process after silver deposition on an Si substrate. Structure and composition of the Ag(2)S are characterized using XRD and RBS. Our samples show semiconductor behaviour at low bias voltages, whereas they exhibit reproducible bipolar resistance switching at higher bias voltages. The transition between both types of behaviour is observed by hysteresis in the I-V curves, indicating decomposition of the Ag(2)S, increasing the Ag(+) ion mobility. The as-fabricated Ag(2)S samples are a good candidate for future solid state memory devices, as they show reproducible memory resistive properties and they are fabricated by an accessible and reliable method.

Nonlinear optical measurements of conducting copolymers of aniline under CW laser excitation

NASA Astrophysics Data System (ADS)

Pramodini, S.; Poornesh, P.

2015-08-01

Synthesis and measurements of third-order optical nonlinearity and optical limiting of conducting copolymers of aniline are presented. Single beam z-scan technique was employed for the nonlinear optical studies. Continuous wave He-Ne laser operating at 633 nm was used as the source of excitation. Copolymer samples exhibited reverse saturable absorption (RSA) process. The nonlinear refraction studies depict that the copolymers exhibit self-defocusing property. The estimated values of βeff, n2 and χ(3) were found to be of the order of 10-2 cm/W, 10-5 esu and 10-7 esu respectively. Self-diffraction rings were observed due to refractive index change when exposed to the laser beam. A good optical limiting and clamping of power of ∼0.9 mW and ∼0.05 mW was observed. Therefore, copolymers of aniline emerge as a potential candidate for photonic device applications.

Hydrothermal synthesis of cobalt sulfide nanotubes: The size control and its application in supercapacitors

NASA Astrophysics Data System (ADS)

Wan, Houzhao; Ji, Xiao; Jiang, Jianjun; Yu, Jingwen; Miao, Ling; Zhang, Li; Bie, Shaowei; Chen, Haichao; Ruan, Yunjun

2013-12-01

Cobalt sulfide nanotubes are synthesized by hydrothermal method. The precursor is characterized by XRD, FTIR and SEM. We study the influence of temperature on the evolution of this special coarse shape nanostructure and analyze relationship between the sizes of cobalt sulfide nanotubes and the capacitive properties of active materials. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are used to study the effects of microstructure and morphology of the samples on their capacitance and conductivity. The specific capacitance of cobalt sulfide nanotubes (obtained in 80 °C) electrode exhibits a capacitance of 285 F g-1 at the current density of 0.5 A g-1 as well as rather good cycling stability. Moreover, during the cycling process, the coulombic efficiency remains 99%. The as-prepared cobalt sulfide nanotubes electrode exhibits excellent electrochemical performance as electrode materials for supercapacitors.

Synthesis, Luminescent Properties of aza-Boron-Diquinomethene Difluoride Complexes and Their Application for Fluorescent Security Inks.

PubMed

Gu, Long; Liu, Rui; Shi, Hong; Wang, Qiang; Song, Guangliang; Zhu, Xiaolin; Yuan, Shidong; Zhu, Hongjun

2016-03-01

Two aza-boron-diquinomethene (aza-BODIQU) complexes bearing phenyl and carbazyl substituents were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. Both complexes exhibit strong (1)π-π* transition absorptions (λ(abs) = 400-540 nm) and intense fluorescent emissions (λ(em) = 440-600 nm, Φ(PL) = 0.93 and 0.78) in CH2Cl2 solution and in solid state at room temperature. Compared to the complex with phenyl groups, the complex bearing carbazyl groups shows significant bathochromic shift in both absorption and emission. This could be attributed to the larger π-electron conjugation of the carbazole unit and intramolecular charge transfer feature from carbazole to aza-BODIQU component. In addition, the complexes exhibit intense photoluminescence and good stability on antacid, anti-alkali and stability in printing ink samples, which makes them potential dopants for the application of fluorescent security inks.

Antioxidant, antinociceptive, and anti-inflammatory effects of carotenoids extracted from dried pepper (Capsicum annuum L.).

PubMed

Hernández-Ortega, Marcela; Ortiz-Moreno, Alicia; Hernández-Navarro, María Dolores; Chamorro-Cevallos, Germán; Dorantes-Alvarez, Lidia; Necoechea-Mondragón, Hugo

2012-01-01

Carotenoids extracted from dried peppers were evaluated for their antioxidant, analgesic, and anti-inflammatory activities. Peppers had a substantial carotenoid content: guajillo 3406 ± 4 μg/g, pasilla 2933 ± 1 μg/g, and ancho 1437 ± 6 μg/g of sample in dry weight basis. A complex mixture of carotenoids was discovered in each pepper extract. The TLC analysis revealed the presence of chlorophylls in the pigment extract from pasilla and ancho peppers. Guajillo pepper carotenoid extracts exhibited good antioxidant activity and had the best scavenging capacity for the DPPH(+) cation (24.2%). They also exhibited significant peripheral analgesic activity at 5, 20, and 80 mg/kg and induced central analgesia at 80 mg/kg. The results suggest that the carotenoids in dried guajillo peppers have significant analgesic and anti-inflammatory benefits and could be useful for pain and inflammation relief.

Antioxidant, Antinociceptive, and Anti-Inflammatory Effects of Carotenoids Extracted from Dried Pepper (Capsicum annuum L.)

PubMed Central

Hernández-Ortega, Marcela; Ortiz-Moreno, Alicia; Hernández-Navarro, María Dolores; Chamorro-Cevallos, Germán; Dorantes-Alvarez, Lidia; Necoechea-Mondragón, Hugo

2012-01-01

Carotenoids extracted from dried peppers were evaluated for their antioxidant, analgesic, and anti-inflammatory activities. Peppers had a substantial carotenoid content: guajillo 3406 ± 4 μg/g, pasilla 2933 ± 1 μg/g, and ancho 1437 ± 6 μg/g of sample in dry weight basis. A complex mixture of carotenoids was discovered in each pepper extract. The TLC analysis revealed the presence of chlorophylls in the pigment extract from pasilla and ancho peppers. Guajillo pepper carotenoid extracts exhibited good antioxidant activity and had the best scavenging capacity for the DPPH+ cation (24.2%). They also exhibited significant peripheral analgesic activity at 5, 20, and 80 mg/kg and induced central analgesia at 80 mg/kg. The results suggest that the carotenoids in dried guajillo peppers have significant analgesic and anti-inflammatory benefits and could be useful for pain and inflammation relief. PMID:23091348

Nano-jewels in biology. Gold and platinum on diamond nanoparticles as antioxidant systems against cellular oxidative stress.

PubMed

Martín, Roberto; Menchón, Cristina; Apostolova, Nadezda; Victor, Victor M; Alvaro, Mercedes; Herance, José Raúl; García, Hermenegildo

2010-11-23

Diamond nanoparticles (DNPs) obtained by explosive detonation have become commercially available. These commercial DNPs can be treated under Fenton conditions (FeSO(4) and H(2)O(2) at acidic pH) to obtain purer DNP samples with a small average particle size (4 nm) and a large population of surface OH groups (HO-DNPs). These Fenton-treated HO-DNPs have been used as a support of gold and platinum nanoparticles (≤2 nm average size). The resulting materials (Au/HO-DNP and Pt/HO-DNP) exhibit a high antioxidant activity against reactive oxygen species induced in a hepatoma cell line. In addition to presenting good biocompatibility, Au/HO- and Pt/HO-DNP exhibit about a two-fold higher antioxidant activity than glutathione, one of the reference antioxidant systems. The most active material against cellular oxidative stress was Au/HO-DNP.

H3PO4 solution hydrothermal carbonization combined with KOH activation to prepare argy wormwood-based porous carbon for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Dai, Changchao; Wan, Jiafeng; Yang, Juan; Qu, Shanshan; Jin, Tieyu; Ma, Fangwei; Shao, Jinqiu

2018-06-01

In this work, argy wormwood-based porous carbon electrode materials for high-performance supercapacitors are prepared through H3PO4 solution hydrothermal carbonization and subsequent KOH activation. The obtained carbon has a specific surface area (SSA) of 927 m2 g-1, a total pore volume of 0.56 cm3 g-1, and a high oxygen (9.38%) content. In three-electrode system, it exhibits specific capacitance of 344 F g-1 at 1 A g-1. Moreover, the symmetric supercapacitor shows an excellent rate capability of 87% retention from 1 A g-1 to 10 A g-1, and a good cycling performance with 91.6% retention over 5000 cycles in 6 M KOH. Therefore, the sample activated by H3PO4 & KOH exhibits an excellent future in energy storage.

Electrochemical sensor for rutin detection based on Au nanoparticle-loaded helical carbon nanotubes

NASA Astrophysics Data System (ADS)

Yang, Haitang; Li, Bingyue; Cui, Rongjing; Xing, Ruimin; Liu, Shanhu

2017-10-01

The key step in the fabrication of highly active electrochemical sensors is seeking multifunctional nanocomposites as electrode modified materials. In this study, the gold nanoparticle-decorated helical carbon nanotube nanocomposites (AuNPs-HCNTs) were fabricated for rutin detection because of its superior sensitivity, the chemical stability of AuNPs, and the superior conductivity and unique 3D-helical structure of helical carbon nanotubes. Results showed the prepared nanocomposites exhibited superior electrocatalytic activity towards rutin due to the synergetic effects of AuNPs and HCNTs. Under the optimized conditions, the developed sensor exhibited a linear response range from 0.1 to 31 μmol/L for rutin with a low detectable limit of 81 nmol/L. The proposed method might offer a possibility for electrochemical analysis of rutin in Chinese medical analysis or serum monitoring owing to its low cost, simplicity, high sensitivity, good stability, and few interferences against common coexisting ions in real samples.

Carrier mediated hollow fiber liquid phase microextraction combined with HPLC-UV for preconcentration and determination of some tetracycline antibiotics.

PubMed

Shariati, Shahab; Yamini, Yadollah; Esrafili, Ali

2009-02-01

In the present study, a simple and efficient preconcentration method was developed using carrier mediated three phase liquid phase microextraction prior to HPLC-UV for simultaneous extraction and determination of trace amounts of highly hydrophilic tetracycline antibiotics including tetracycline (TCN), oxytetracycline (OTCN) and doxycycline (DCN) in bovine milk, human plasma and water samples. For extraction, 11.0 mL of the aqueous sample containing TCNs and 0.05 M Na(2)HPO(4) (9.10.995). Finally, applicability of the proposed method was successfully confirmed by extraction and determination of the drugs in water and plasma samples as well as in bovine milk samples with low and high fat contents. Comparing to the traditional methods, the proposed method exhibits high sensitivity and high preconcentration factors as well as good precision. The extraction setup is simple and due to active transport of analytes, high cleanup effect and good selectivity are obtained in extraction process.

Development of electrochemical folic acid sensor based on hydroxyapatite nanoparticles.

PubMed

Kanchana, P; Sekar, C

2015-02-25

We report the synthesis of hydroxyapatite (HA) nanoparticles (NPs) by a simple microwave irradiation method and its application as sensing element for the precise determination of folic acid (FA) by electrochemical method. The structure and composition of the HA NPs characterized using XRD, FTIR, Raman and XPS. SEM and EDX studies confirmed the formation of elongated spherical shaped HA NPs with an average particle size of about 34 nm. The HA NPs thin film on glassy carbon electrode (GCE) were deposited by drop casting method. Electrocatalytic behavior of FA in the physiological pH 7.0 was investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry. The fabricated HA/GCE exhibited a linear calibration plot over a wide FA concentration ranging from 1.0×10(-7) to 3.5×10(-4) M with the detection limit of 75 nM. In addition, the HA NPs modified GCE showed good selectivity toward the determination of FA even in the presence of a 100-fold excess of ascorbic acid (AA) and 1000-fold excess of other common interferents. The fabricated biosensor exhibits good sensitivity and stability, and was successfully applied for the determination of FA in pharmaceutical samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Thick Smear is a Good Substitute for the Thin Smear in Parasitological Confirmation of Canine Visceral Leishmaniasis.

PubMed

de Mello, Cintia Xavier; Figueiredo, Fabiano Borges; Mendes Júnior, Artur Augusto Velho; Miranda, Luciana de Freitas Campos; de Oliveira, Raquel de Vasconcellos Carvalhaes; Madeira, Maria de Fátima

2016-07-06

Although direct examination methods are important for diagnosing leishmaniasis, such methods are often neglected because of their low sensitivity relative to other techniques. Our study aimed to evaluate the performance of bone marrow (BM) thick smears and cytocentrifugation tests as alternatives to direct examination for diagnosing canine visceral leishmaniasis (CVL). Ninety-two dogs exhibiting leishmaniasis seroreactivity were evaluated. The animals were euthanized; and healthy skin, spleen, popliteal lymph node, and BM puncture samples were cultured. BM cultures were used as the reference standard. Of the 92 dogs studied, 85.9% exhibited positive cultures, and Leishmania infantum (synonym Leishmania chagasi) was confirmed in all positive culture cases. The sensitivity rates for cytocentrifugation as well as thin and thick smears were 47.1%, 52.8%, and 77%, respectively. However, no association between the dogs' clinical status and culture or direct examination results was found. To our knowledge, this was the first study to use thick smears and cytocentrifugation for diagnosing CVL. Our results indicate that BM thick smears have a good sensitivity and their use reduces the time required to read slides. Therefore, thick smears can provide a rapid and safe alternative to parasitological confirmation of seroreactive dogs. © The American Society of Tropical Medicine and Hygiene.

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.

A dual-responsive colorimetric and fluorescent chemosensor based on diketopyrrolopyrrole derivative for naked-eye detection of Fe3 + and its practical application

NASA Astrophysics Data System (ADS)

Zhang, Shanshan; Sun, Tao; Xiao, Dejun; Yuan, Fang; Li, Tianduo; Wang, Enhua; Liu, Haixia; Niu, Qingfen

2018-01-01

A novel dual-responsive colorimetric and fluorescent chemosensor L based on diketopyrrolopyrrole derivative for Fe3 + detection was designed and synthesized. In presence of Fe3 +, sensor L displayed strong colorimetric response as amaranth to rose pink and significant fluorescence enhancement and chromogenic change, which served as a naked-eye indicator by an obvious color change from purple to red. The binding constant for L-Fe3 + complex was found as 2.4 × 104 with the lower detection limit of 14.3 nM. The sensing mechanism was investigated in detail by fluorescence measurements, IR and 1H NMR spectra. Sensor L for Fe3 + detection also exhibited high anti-interference performance, good reversibility, wide pH response range and instantaneous response time. Furthermore, the sensor L has been used to quantify Fe3 + ions in practical water samples with good recovery.

A Flemion-based actuator with ionic liquid as solvent

NASA Astrophysics Data System (ADS)

Wang, Jin; Xu, Chunye; Taya, Minoru; Kuga, Yasuo

2007-04-01

A perfluorinated carboxylic acid membrane, i.e. Flemion, shows improved performance as actuator material compared with Nafion (perfluorinated sulfonic acid). Flemion has a higher ion exchange capacity and good mechanical strength. In particular, Flemion will deform with no back relaxation under applied electrical stimulus. However, with water as solvent, the operation of Flemion in air has serious problems, since water would evaporate quickly in air. Moreover, the electrochemical stability for use in water is around 1 V at room temperature. In previous work, investigations on Nafion with ionic liquid as solvents have been carried out by some researchers and good results have been obtained. In this work, we explore the use of highly stable ionic liquid instead of water as solvent in Flemion. Experimental results indicate that Flemion-based actuators with ionic liquid as solvent have improved stability as compared to the water samples. Although the forces exhibited by Flemion-based actuators with the use of ionic liquid decreased dramatically compared to water, these preliminary results suggest good potential for the use of Flemion with ionic liquid in future applications.

Flemion-based actuator with ionic liquid as solvent

NASA Astrophysics Data System (ADS)

Wang, Jin; Xu, Chunye; Taya, Minoru; Kuga, Yasuo

2006-03-01

A perfluorinated carboxylic acid membrane, i.e. Flemion, shows improved performance as actuator material compared with Nafion (perfluorinated sulfonic acide). Flemion has a higher ion exchange capacity and good mechanical strength. Especially, Flemion will deform with no back relaxation when applied electrical stimulus. However, with water as solvent, the operation of Flemion in air has serious problems. Since water would evaporate quickly in air. Moreover, the electrochemical stability for use in water is around 1V at room temperature. In previous work, investigations on Nafion with ionic liquid as solvents have been carried out and good results have been obtained. In this work, we explore the use of highly stable ionic liquid instead of water as solvent in Flemion. Experimental results indicate that Flemion based actuators with ionic liquid as solvent have improved stability as compared to the water samples. Although the forces exhibited by Flemion based actuators with the use of ionic liquid decreased dramatically as compared to water, these preliminary results suggest a good potential for use of Flemion with ionic liquid in some applications.

Cross-sectional survey of Good Samaritan behaviour by physicians in North Carolina.

PubMed

Garneau, William M; Harris, Dean M; Viera, Anthony J

2016-03-10

To assess the responses of physicians to providing emergency medical assistance outside of routine clinical care. We assessed the percentage who reported previous Good Samaritan behaviour, their responses to hypothetical situations, their comfort providing specific interventions and the most likely reason they would not intervene. Physicians residing in North Carolina. Convenience sample of 1000 licensed physicians. Mailed survey. Cross-sectional study conducted May 2015 to September 2015. Willingness of physicians to act as Good Samaritans as determined by the last opportunity to intervene in an out-of-office emergency. The adjusted response rate was 26.1% (253/970 delivered). 4 out of 5 physicians reported previous opportunities to act as Good Samaritans. Approximately, 93% reported acting as a Good Samaritan during their last opportunity. There were no differences in this outcome between sexes, practice setting, specialty type or experience level. Doctors with greater perceived knowledge of Good Samaritan law were more likely to have intervened during a recent opportunity (p=0.02). The most commonly cited reason for potentially not intervening was that another health provider had taken charge. We found the frequency of Good Samaritan behaviour among physicians to be much higher than reported in previous studies. Greater helping behaviour was exhibited by those who expressed more familiarity with Good Samaritan law. These findings suggest that physicians may respond to legal protections. 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/

76 FR 4929 - Agency Information Collection Activities: Entry of Articles for Exhibition.

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-27

... Activities: Entry of Articles for Exhibition. AGENCY: U.S. Customs and Border Protection (CBP), Department of... requirement concerning the Entry of Articles for Exhibition (19 CFR 147.11(c)). This request for comment is...: Title: Entry of Articles for Exhibition. OMB Number: 1651-0037. Form Number: None. Abstract: Goods...

Towards the determination of sulfonamides in meat samples: A magnetic and mesoporous metal-organic framework as an efficient sorbent for magnetic solid phase extraction combined with high-performance liquid chromatography.

PubMed

Xia, Lian; Liu, Lijie; Lv, Xiaoxia; Qu, Fei; Li, Guoliang; You, Jinmao

2017-06-02

A magnetic, mesoporous core/shell structured Fe 3 O 4 @JUC-48 nanocomposite was synthesized and employed as a magnetic solid phase extraction (MSPE) sorbent for the determination of trace sulfonamides (SAs) in meat samples. The synthesized nanocomposite was characterized by X-ray diffraction, Fourier transform infrared spectra, transmission electron microscopy, scanning electron microscopy, Brunner-Emmet-Teller, and vibrating sample magnetometry; the Fe 3 O 4 @JUC-48 nanocomposite exhibited a distinctive morphology, large surface area, high magnetism, open adsorption sites, and high chemical stability. By combining the optimized MSPE conditions with high performance liquid chromatography diode array detection, an accurate and sensitive method for the determination of 5 SAs, including sulfadiazine (SDZ), sulfathiazole (STZ), sulfamerazine (SMR), sulfamethazine (SMZ), and sulfamethoxypyridazine (SMP), was developed. The method exhibited good linearity in the range of 3.97-1000ng/g with R ranging from 0.9991 to 0.9994, high sensitivity with LODs ranging from 1.73 to 5.23ng/g, adequate recoveries between 76.1 and 102.6% with low relative standard deviations ranging from 2.1 to 6.4%, and high precision with RSD<4.5%. The Fe 3 O 4 @JUC-48 magnetic nanocomposite is a promising sorbent for the rapid and efficient extraction of SAs from complex biological samples such as chicken, pork, and shrimp. Copyright © 2017 Elsevier B.V. All rights reserved.

Highly selective and sensitive methanol gas sensor based on molecular imprinted silver-doped LaFeO3 core-shell and cage structures

NASA Astrophysics Data System (ADS)

Rong, Qian; Zhang, Yumin; Lv, Tianping; Shen, Kaiyuan; Zi, Baoye; Zhu, Zhongqi; Zhang, Jin; Liu, Qingju

2018-04-01

Silver-doped LaFeO3 molecularly imprinted polymers (SLMIPs) were synthesized by a sol-gel method combined with molecularly imprinted technology as precursors. The precursors were then used to prepare SLMIPs cage (SLM-cage) and SLMIPs core-shell (SLM-core-shell) structures by using a carbon sphere as the template and hydrothermal synthesis, respectively. The structures, morphologies, and surface areas of these materials were determined, as well as their gas-sensing properties and related mechanisms. The SLM-cage and SLM-core-shell samples exhibited good responses to methanol gas, with excellent selectivity. The response and optimum working temperature were 16.98 °C and 215 °C, 33.7 °C and 195 °C, respectively, with corresponding response and recovery times of 45 and 50 s (SLM-cage) and 42 and 57 s (SLM-core-shell) for 5 ppm methanol gas. Notably, the SLM-cage and SLM-core-shell samples exhibited lower responses (≤5 and ≤7, respectively) to other gases, including ethanol, ammonia, benzene, acetone, and toluene. Thus, these materials show potential as practical methanol detectors.

Up-Conversion Y2O3:Yb(3+),Er(3+) Hollow Spherical Drug Carrier with Improved Degradability for Cancer Treatment.

PubMed

Ge, Kun; Zhang, Cuimiao; Sun, Wentong; Liu, Huifang; Jin, Yi; Li, Zhenhua; Liang, Xing-Jie; Jia, Guang; Zhang, Jinchao

2016-09-28

The rare earth hollow spheres with up-conversion luminescence properties have shown potential applications in drug delivery and bioimaging fields. However, there have been few reports for the degradation properties of rare earth oxide drug carriers. Herein, uniform and well-dispersed Y2O3:Yb(3+),Er(3+) hollow spheres (YOHSs) have been fabricated by a general Pechini sol-gel process with melamine formaldehyde colloidal spheres as template. The novel YOHSs with up-conversion luminescence has good drug loading amount and drug-release efficiency; moreover, it exhibits pH-responsive release patterns. In particular, the YOHSs sample exhibits low cytotoxicity and excellent degradable properties in acid buffer. After the sample was loaded with anticancer drug doxorubicin (DOX), the antitumor result in vitro indicates that YOHS-DOX might be effective in cancer treatment. The animal imaging test also reveals that the YOHSs drug carrier can be used as an outstanding luminescent probe for bioimaging in vivo application prospects. The results suggest that the degradable drug carrier with up-conversion luminescence may enhance the delivery efficiency of drugs and improve the cancer therapy in clinical applications.

Effect of surface microstructure on electrochemical performance of garnet solid electrolytes.

PubMed

Cheng, Lei; Chen, Wei; Kunz, Martin; Persson, Kristin; Tamura, Nobumichi; Chen, Guoying; Doeff, Marca

2015-01-28

Cubic garnet phases based on Al-substituted Li7La3Zr2O12 (LLZO) have high ionic conductivities and exhibit good stability versus metallic lithium, making them of particular interest for use in next-generation rechargeable battery systems. However, high interfacial impedances have precluded their successful utilization in such devices until the present. Careful engineering of the surface microstructure, especially the grain boundaries, is critical to achieving low interfacial resistances and enabling long-term stable cycling with lithium metal. This study presents the fabrication of LLZO heterostructured solid electrolytes, which allowed direct correlation of surface microstructure with the electrochemical characteristics of the interface. Grain orientations and grain boundary distributions of samples with differing microstructures were mapped using high-resolution synchrotron polychromatic X-ray Laue microdiffraction. The electrochemical characteristics are strongly dependent upon surface microstructure, with small grained samples exhibiting much lower interfacial resistances and better cycling behavior than those with larger grain sizes. Low area specific resistances of 37 Ω cm(2) were achieved; low enough to ensure stable cycling with minimal polarization losses, thus removing a significant obstacle toward practical implementation of solid electrolytes in high energy density batteries.

A direct comparison between gas state and atomised liquid state precursor in the deposition of functional coatings by pin corona plasma

NASA Astrophysics Data System (ADS)

Herbert, P. A. F.; Jaroszyńska-Wolińska, J.

2011-07-01

An atmospheric pressure non-thermal equilibrium pin corona plasma jet was used to deposit polymeric coatings from monomer precursor in both vapour and liquid aerosol states to allow a direct comparison of the quality and performance of the as-deposited coatings, specifically with respect to the achievement of soft plasma polymerisation (SPP) where the coating exhibits minimal fragmentation or damage to the monomer molecule while, at the same time, being highly cross-linked. A long chain perfluorocarbon molecule was introduced into the helium plasma and coatings deposited at rates of up to 50 nm/min. XPS, FTIR, contact angle and ellipsometric measurements indicated that a controlled polymerisation reaction had taken place in the case of the vapour deposited samples through the vinyl group of the monomer, with only minor fragmentation of the functional perfluoro chain. Furthermore, a high level of cross-linking was achieved and the coatings were stable to a toluene wash. In contrast, while the liquid deposition samples showed good retention of monomer molecular structure, they exhibited negligible cross-linking and were readily removed by immersion in toluene rendering them functionally useless.

Highly selective and sensitive methanol gas sensor based on molecular imprinted silver-doped LaFeO3 core-shell and cage structures.

PubMed

Rong, Qian; Zhang, Yumin; Lv, Tianping; Shen, Kaiyuan; Zi, Baoye; Zhu, Zhongqi; Zhang, Jin; Liu, Qingju

2018-04-06

Silver-doped LaFeO 3 molecularly imprinted polymers (SLMIPs) were synthesized by a sol-gel method combined with molecularly imprinted technology as precursors. The precursors were then used to prepare SLMIPs cage (SLM-cage) and SLMIPs core-shell (SLM-core-shell) structures by using a carbon sphere as the template and hydrothermal synthesis, respectively. The structures, morphologies, and surface areas of these materials were determined, as well as their gas-sensing properties and related mechanisms. The SLM-cage and SLM-core-shell samples exhibited good responses to methanol gas, with excellent selectivity. The response and optimum working temperature were 16.98 °C and 215 °C, 33.7 °C and 195 °C, respectively, with corresponding response and recovery times of 45 and 50 s (SLM-cage) and 42 and 57 s (SLM-core-shell) for 5 ppm methanol gas. Notably, the SLM-cage and SLM-core-shell samples exhibited lower responses (≤5 and ≤7, respectively) to other gases, including ethanol, ammonia, benzene, acetone, and toluene. Thus, these materials show potential as practical methanol detectors.

Spitzer SAGE-Spec: Near infrared spectroscopy, dust shells, and cool envelopes in extreme Large Magellanic Cloud asymptotic giant branch stars

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

Blum, R. D.; Srinivasan, S.; Kemper, F.

2014-11-01

K-band spectra are presented for a sample of 39 Spitzer Infrared Spectrograph (IRS) SAGE-Spec sources in the Large Magellanic Cloud. The spectra exhibit characteristics in very good agreement with their positions in the near-infrared—Spitzer color-magnitude diagrams and their properties as deduced from the Spitzer IRS spectra. Specifically, the near-infrared spectra show strong atomic and molecular features representative of oxygen-rich and carbon-rich asymptotic giant branch stars, respectively. A small subset of stars was chosen from the luminous and red extreme ''tip'' of the color-magnitude diagram. These objects have properties consistent with dusty envelopes but also cool, carbon-rich ''stellar'' cores. Modest amountsmore » of dust mass loss combine with the stellar spectral energy distribution to make these objects appear extreme in their near-infrared and mid-infrared colors. One object in our sample, HV 915, a known post-asymptotic giant branch star of the RV Tau type, exhibits CO 2.3 μm band head emission consistent with previous work that demonstrates that the object has a circumstellar disk.« less

Is sperm freezability related to the post-thaw lipid peroxidation and the formation of reactive oxygen species in boars?

PubMed

Gómez-Fernández, J; Gómez-Izquierdo, E; Tomás, C; Mocé, E; de Mercado, E

2013-04-01

The aim of the present study was to determine whether the levels of reactive oxygen species (ROS) substances production and the levels of lipid peroxidation of the sperm membrane were related to the quality that the ejaculates exhibited after cryopreservation in boars. Ejaculates from 42 healthy boars were used in this study and they were cryopreserved with the lactose-egg yolk extender (LEY). Several sperm quality parameters were assessed by flow cytometry in samples incubated for 30 and 150 min at 37 °C after thawing: the percentage of sperm with intact plasma membrane (SIPM), intracellular reactive oxygen substances production through mean of DCF fluorescence intensity of total sperm (mean-DCF) and the percentage of viable and non-viable sperm containing oxidized BODIPY (VSOB and NVSOB). In addition, the percentages of total motile (TMS) and progressively motile sperm (PMS) were assessed at the same incubation times with a computer-assisted sperm analysis system. The classification of the ejaculates into good or bad freezers was performed through hierarchical cluster analysis from SIPM and TMS at 150 min post-thawing. The ejaculates of those males classified as good freezers exhibited higher (p < 0.05) SPIM, TMS and PMS than the bad freezers, although both groups presented similar (p > 0.05) VSOB, NVSOB and mean-DCF. Therefore, these results show that lipid peroxidation and the amount of reactive oxygen substances in the sperm after cryopreservation are similar between boars classified as good or bad freezers. © 2012 Blackwell Verlag GmbH.

Disposable MoS2-Arrayed MALDI MS Chip for High-Throughput and Rapid Quantification of Sulfonamides in Multiple Real Samples.

PubMed

Zhao, Yaju; Tang, Minmin; Liao, Qiaobo; Li, Zhoumin; Li, Hui; Xi, Kai; Tan, Li; Zhang, Mei; Xu, Danke; Chen, Hong-Yuan

2018-04-27

In this work, we demonstrate, for the first time, the development of a disposable MoS 2 -arrayed matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) chip combined with an immunoaffinity enrichment method for high-throughput, rapid, and simultaneous quantitation of multiple sulfonamides (SAs). The disposable MALDI MS chip was designed and fabricated by MoS 2 array formation on a commercial indium tin oxide (ITO) glass slide. A series of SAs were analyzed, and clear deprotonated signals were obtained in negative-ion mode. Compared with MoS 2 -arrayed commercial steel plate, the prepared MALDI MS chip exhibited comparable LDI efficiency, providing a good alternative and disposable substrate for MALDI MS analysis. Furthermore, internal standard (IS) was previously deposited onto the MoS 2 array to simplify the experimental process for MALDI MS quantitation. 96 sample spots could be analyzed within 10 min in one single chip to perform quantitative analysis, recovery studies, and real foodstuff detection. Upon targeted extraction and enrichment by antibody conjugated magnetic beads, five SAs were quantitatively determined by the IS-first method with the linear range of 0.5-10 ng/mL ( R 2 > 0.990). Good recoveries and repeatability were obtained for spiked pork, egg, and milk samples. SAs in several real foodstuffs were successfully identified and quantified. The developed method may provide a promising tool for the routine analysis of antibiotic residues in real samples.

Rapid determination of 54 pharmaceutical and personal care products in fish samples using microwave-assisted extraction-Hollow fiber-Liquid/solid phase microextraction.

PubMed

Zhang, Yi; Guo, Wen; Yue, Zhenfeng; Lin, Li; Zhao, Fengjuan; Chen, Peijin; Wu, Weidong; Zhu, Hong; Yang, Bo; Kuang, Yanyun; Wang, Jiong

2017-04-15

In this paper, a simple, rapid, solvent-less and environmental friendliness microextraction method, microwave-assisted extraction-hollow fiber-liquid/solid phase microextraction (MAE-HF-L/SME), was developed for simultaneous extraction and enrichment of 54 trace hydrophilic/lipophilic pharmaceutical and personal care products (PPCPs) from fish samples. A solid-phase extraction material, solid-phase microextraction (SPME) fiber, was synthesized. The SPME fiber had a homogeneous, loose structure and good mechanical properties, and they exhibited a good adsorption capacity for most PPCPs selected. The material formed the basis for the method of MAE-HF-L/SME. A method of liquid chromatography-high resolution mass spectroscopy (LC-HRMS) for analysis of 54 PPCPs. Under optimal synthesis and extraction conditions, the limits of detection (LODs, n=3) and the limits of quantitation (LOQs, n=10) for the 54 PPCPs were between 0.01-0.50μg·kg -1 and 0.052.00μg·kg -1 , respectively. Percent recoveries and the relative standard deviations (RSDs) in spiked fish samples (n=6) were between 56.3%-119.9% and 0.3%-17.1%, respectively. The microextraction process of 54 PPCPs in MAE-HF-L/SME took approximately 12min. The method has a low matrix interference and high enrichment factor and may be applicable for determination of 54 different PPCPs in fish samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of Coatings on the High-Cycle Fatigue Life of Threaded Steel Samples

NASA Astrophysics Data System (ADS)

Eder, M. A.; Haselbach, P. U.; Mishin, O. V.

2018-05-01

In this work, high-cycle fatigue is studied for threaded cylindrical high-strength steel samples coated using three different industrial processes: black oxidation, normal-temperature galvanization and high-temperature galvanization. The fatigue performance in air is compared with that of uncoated samples. Microstructural characterization revealed the abundant presence of small cracks in the zinc coating partially penetrating into the steel. This is consistent with the observation of multiple crack initiation sites along the thread in the galvanized samples, which led to crescent type fracture surfaces governed by circumferential growth. In contrast, the black oxidized and uncoated samples exhibited a semicircular segment type fracture surface governed by single-sided growth with a significantly longer fatigue life. Numerical fatigue life prediction based on an extended Paris-law formulation has been conducted on two different fracture cases: 2D axisymmetric multisided crack growth and 3D single-sided crack growth. The results of this upper-bound and lower-bound approach are in good agreement with experimental data and can potentially be used to predict the lifetime of bolted components.

Development of a novel method for amniotic fluid stem cell storage.

PubMed

Zavatti, Manuela; Beretti, Francesca; Casciaro, Francesca; Comitini, Giuseppina; Franchi, Fabrizia; Barbieri, Veronica; Bertoni, Laura; De Pol, Anto; La Sala, Giovanni B; Maraldi, Tullia

2017-08-01

Current procedures for collection of human amniotic fluid stem cells (hAFSCs) indicate that cells cultured in a flask for 2 weeks can then be used for research. However, hAFSCs can be retrieved directly from a small amount of amniotic fluid that can be obtained at the time of diagnostic amniocentesis. The aim of this study was to determine whether direct freezing of amniotic fluid cells is able to maintain or improve the potential of a sub-population of stem cells. We compared the potential of the hAFSCs regarding timing of freezing, cells obtained directly from amniotic fluid aspiration (D samples) and cells cultured in a flask before freezing (C samples). Colony-forming-unit ability, proliferation, morphology, stemness-related marker expression, senescence, apoptosis and differentiation potential of C and D samples were compared. hAFSCs isolated from D samples expressed mesenchymal stem cells markers until later passages, had a good proliferation rate and exhibited differentiation capacity similar to hAFSCs of C samples. Interestingly, direct freezing induced a higher concentration of cells positive for pluripotency stem cell markers, without teratoma formation in vivo. This study suggests that minimal processing may be adequate for the banking of amniotic fluid cells, avoiding in vitro passages before the storage and exposure to high oxygen concentration, which affect stem cell properties. This technique might be a cost-effective and reasonable approach to the process of Good Manufacturing Process accreditation for stem-cell banks. Copyright © 2017 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Multiple functional ionic liquids based dispersive liquid-liquid microextraction combined with high performance chromatography for the determination of phenolic compounds in water samples.

PubMed

Sun, Jian-Nan; Chen, Juan; Shi, Yan-Ping

2014-07-01

A new mode of ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME) is developed. In this work, [C6MIm][PF6] was chosen as the extraction solvent, and two kinds of hydrophilic ionic liquids, [EMIm][BF4] and [BSO3HMIm][OTf], functioned as the dispersive solvent. So in the whole extraction procedure, no organic solvent was used. With the aid of SO3H group, the acidic compound was extracted from the sample solution without pH adjustment. Two phenolic compounds, namely, 2-naphthol and 4-nitrophenol were chosen as the target analytes. Important parameters affecting the extraction efficiency, such as the type of hydrophilic ionic liquids, the volume ratio of [EMIm][BF4] to [BSO3HMIm][OTf], type and volume of extraction solvent, pH value of sample solution, sonication time, extraction time and centrifugation time were investigated and optimized. Under the optimized extraction conditions, the method exhibited good sensitivity with the limits of detection (LODs) at 5.5 μg L(-1)and 10.0 μg L(-1) for 4-nitrophenol and 2-naphthol, respectively. Good linearity over the concentration ranges of 24-384 μg L(-1) for 4-nitrophenol and 28-336 μg L(-1) for 2-naphthol was obtained with correlation coefficients of 0.9998 and 0.9961, respectively. The proposed method can directly extract acidic compound from environmental sample or even more complex sample matrix without any pH adjustment procedure. Copyright © 2014 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.

Preparation of amorphous solid dispersions by rotary evaporation and KinetiSol Dispersing: approaches to enhance solubility of a poorly water-soluble gum extract.

PubMed

Bennett, Ryan C; Brough, Chris; Miller, Dave A; O'Donnell, Kevin P; Keen, Justin M; Hughey, Justin R; Williams, Robert O; McGinity, James W

2015-03-01

Acetyl-11-keto-β-boswellic acid (AKBA), a gum resin extract, possesses poor water-solubility that limits bioavailability and a high melting point making it difficult to successfully process into solid dispersions by fusion methods. The purpose of this study was to investigate solvent and thermal processing techniques for the preparation of amorphous solid dispersions (ASDs) exhibiting enhanced solubility, dissolution rates and bioavailability. Solid dispersions were successfully produced by rotary evaporation (RE) and KinetiSol® Dispersing (KSD). Solid state and chemical characterization revealed that ASD with good potency and purity were produced by both RE and KSD. Results of the RE studies demonstrated that AQOAT®-LF, AQOAT®-MF, Eudragit® L100-55 and Soluplus with the incorporation of dioctyl sulfosuccinate sodium provided substantial solubility enhancement. Non-sink dissolution analysis showed enhanced dissolution properties for KSD-processed solid dispersions in comparison to RE-processed solid dispersions. Variances in release performance were identified when different particle size fractions of KSD samples were analyzed. Selected RE samples varying in particle surface morphologies were placed under storage and exhibited crystalline growth following solid-state stability analysis at 12 months in comparison to stored KSD samples confirming amorphous instability for RE products. In vivo analysis of KSD-processed solid dispersions revealed significantly enhanced AKBA absorption in comparison to the neat, active substance.

Sugaring marble in the Monumental Cemetery in Bologna (Italy): characterization of naturally and artificially weathered samples and first results of consolidation by hydroxyapatite

NASA Astrophysics Data System (ADS)

Sassoni, Enrico; Franzoni, Elisa

2014-12-01

The so-called sugaring of marble is a very common degradation phenomenon, affecting both historical monuments and modern buildings, which is originated by environmental temperature fluctuations. Thermal cycles are indeed responsible for micro-cracks formation at the boundaries between calcite grains, so that marble is subjected to granular disintegration and can be reduced to a sugar-like powder of isolated calcite grains by just the pressure of a finger. Since no effective, compatible and durable treatment for sugaring marble consolidation is currently available, in this paper a novel consolidating treatment recently proposed for limestone, based on the formation of hydroxyapatite inside the stone, was investigated for weathered marble. To test the new treatment on suitably decayed marble samples, some naturally sugaring marbles from the Monumental Cemetery in Bologna (Italy, nineteenth century) were firstly characterized by scanning electron microscope (SEM), mercury intrusion porosimetry (MIP) and ultrasonic pulse velocity (UPV) measurement. Then, artificially weathered samples were produced by heating fresh Carrara marble samples at 400 °C for 1 h. The effects of artificial weathering were characterized using the same techniques as above, and a very good agreement was found between microstructure and mechanical features of naturally and artificially weathered samples. Then, the hydroxyapatite-based treatment was tested on the so-obtained artificially weathered samples, and the treatment effects were characterized by UPV, MIP and SEM equipped with energy dispersive spectrometry and Fourier transform infrared spectroscopy. The hydroxyapatite-based treatment exhibited a remarkable ability of restoring marble cohesion and a good compatibility in terms of modifications in pore size distribution, which leads to regard this treatment as a very promising consolidant for weathered marble.

Validation of a Chinese version of the stress overload scale-short and its use as a screening tool for mental health status.

PubMed

Duan, Wenjie; Mu, Wenlong

2018-02-01

Although stress emerges when environmental demands exceed personal resources, existing measurement methods for stress focus only on one aspect. The newly-developed Short Stress Overload Scale (SOS-S) assesses the extent of stress by assessing both event load (i.e., environmental demands) and personal vulnerability (i.e., personal resources). The present study was designed to evaluate the psychometric properties of the Chinese version of Stress Overload Scale-Short (SOS-SC), and further examine its roles in screening mental health status. A total of 1364 participants were recruited from communities and colleges for scale validation. Reliabilities were good throughout the subsamples (ω > 0.80). Confirmatory factor analysis indicated the acceptable goodness-of-fit for the two-factor correlated model (Sample 1: 560 community residents). Multi-group confirmatory factor analysis confirmed measurement invariance across community residents (Sample 1) and college students (Sample 2 and Sample 3). Criterion validity and convergent validity were established (Sample 2: 554 college students). Latent moderated structural equations demonstrated that the relationship between SOS-SC and depression is moderated by social support (Sample 2), further validating the SOS-SC. In addition, the SOS-SC effectively screened individuals in a population at different levels of mental health status (i.e., "at risk" vs. "at low risk" for depression symptoms and/or wellbeing). The SOS-SC exhibits acceptable psychometric properties in the Chinese context. That said, the two aspects of stress can be differentiated by the Chinese context, therefore, the SOS-SC can be used to measure stress and screen mental health status among the Chinese population, and monitor and evaluate health-promoting interventions.

Reusable nanosilver-coated magnetic particles for ultrasensitive SERS-based detection of malachite green in water samples

NASA Astrophysics Data System (ADS)

Song, Dan; Yang, Rong; Wang, Chongwen; Xiao, Rui; Long, Feng

2016-03-01

A novel nanosilver-deposited silica-coated Fe3O4 magnetic particle (Fe3O4@SiO2@Ag) with uniform size, good SERS activity and magnetic responsiveness was synthesized using amination polymer. The Fe3O4@SiO2@Ag magnetic particles have been successfully applied for ultrasensitive SERS detection of malachite green (MG) in water samples. The mechanism is that MG can be adsorbed on the silver surface of nanosilver-coated magnetic particles via one nitrogen atom, and the Raman signal intensity of MG is significantly enhanced by the nanosilver layer formed on the magnetic particles. The developed sensing system exhibited a sensitive response to MG in the range of 10 fM to 100 μM with a low limit of detection (LOD) 2 fM under optimal conditions. The LOD was several orders of magnitude lower than those of other methods. This SERS-based sensor showed good reproducibility and stability for MG detection. The silver-coated magnetic particles could easily be regenerated as SERS substrates only using low pH solution for multiple sensing events. The recovery of MG added to several water samples at different concentrations ranged from 90% to 110%. The proposed method facilitates the ultrasensitive analysis of dyes to satisfy the high demand for ensuring the safety of water sources.

Application of sunflower stalk-carbon nitride nanosheets as a green sorbent in the solid-phase extraction of polycyclic aromatic hydrocarbons followed by high-performance liquid chromatography.

PubMed

Marzi Khosrowshahi, Elnaz; Razmi, Habib

2018-02-08

A green biocomposite of sunflower stalks and graphitic carbon nitride nanosheets has been applied as a solid-phase extraction adsorbent for sample preparation of five polycyclic aromatic hydrocarbons in different solutions using high-performance liquid chromatography with ultraviolet detection. Before the modification, sunflower stalks exhibited relatively low adsorption to the polycyclic aromatic hydrocarbons extraction. The modified sunflower stalks showed increased adsorption to the analytes extraction due to the increase in surface and existence of a π-π interaction between the analytes and graphitic carbon nitride nanosheets on the surface. Under the optimal conditions, the limits of detection and quantification for five polycyclic aromatic hydrocarbons compounds could reach 0.4-32 and 1.2-95 ng/L, respectively. The method accuracy was evaluated using recovery measurements in spiked real samples and good recoveries from 71 to 115% with relative standard deviations of <10% have been achieved. The developed method was successfully applied for polycyclic aromatic hydrocarbons determination in various samples-well water, tap water, soil, vegetable, and barbequed meat (kebab)-with analytes contents ranging from 0.065 to 13.3 μg/L. The prepared green composite as a new sorbent has some advantages including ease of preparation, low cost, and good reusability. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reusable nanosilver-coated magnetic particles for ultrasensitive SERS-based detection of malachite green in water samples

PubMed Central

Song, Dan; Yang, Rong; Wang, Chongwen; Xiao, Rui; Long, Feng

2016-01-01

A novel nanosilver-deposited silica-coated Fe3O4 magnetic particle (Fe3O4@SiO2@Ag) with uniform size, good SERS activity and magnetic responsiveness was synthesized using amination polymer. The Fe3O4@SiO2@Ag magnetic particles have been successfully applied for ultrasensitive SERS detection of malachite green (MG) in water samples. The mechanism is that MG can be adsorbed on the silver surface of nanosilver-coated magnetic particles via one nitrogen atom, and the Raman signal intensity of MG is significantly enhanced by the nanosilver layer formed on the magnetic particles. The developed sensing system exhibited a sensitive response to MG in the range of 10 fM to 100 μM with a low limit of detection (LOD) 2 fM under optimal conditions. The LOD was several orders of magnitude lower than those of other methods. This SERS-based sensor showed good reproducibility and stability for MG detection. The silver-coated magnetic particles could easily be regenerated as SERS substrates only using low pH solution for multiple sensing events. The recovery of MG added to several water samples at different concentrations ranged from 90% to 110%. The proposed method facilitates the ultrasensitive analysis of dyes to satisfy the high demand for ensuring the safety of water sources. PMID:26964502

Simultaneous determination of parabens, alkylphenols, phenylphenols, bisphenol A and triclosan in human urine, blood and breast milk by continuous solid-phase extraction and gas chromatography-mass spectrometry.

PubMed

Azzouz, Abdelmonaim; Rascón, Andrés J; Ballesteros, Evaristo

2016-02-05

A highly sensitive gas chromatography-mass spectrometry (GC-MS) method for the determination of endocrine disrupting chemicals (EDCs) including parabens, alkylphenols, phenylphenols, bisphenol A and triclosan in human breast milk, blood and urine samples is proposed. Blood and milk require a pretreatment to remove proteins and other substances potentially interfering with the continuous solid-phase extraction (SPE) system used; on the other hand, urine samples can be directly introduced into the system after filtering. Analytes are retained on a LiChrolut EN column and derivatized by silylation following elution with acetonitrile. The resulting trimethylsilyl derivatives are determined by GC-MS. The proposed method exhibited good linearity (r(2)>0.995) for all target EDCs over the concentration range 0.7-10,000ng/l in urine, and 3.3-50,000ng/l in blood and milk. Also, it provided low limits of detection (0.2-1.8ng/l in urine, and 1.0-9.0ng/l in blood and milk), good precision (relative standard deviations less than 7%) and recoveries from 86 to 104%. A total of 24 human fluid samples were analyzed and most found to contain some target EDC at concentrations from 0.10 to 14μg/l. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of phthalate esters in drinking water and edible vegetable oil samples by headspace solid phase microextraction using graphene/polyvinylchloride nanocomposite coated fiber coupled to gas chromatography-flame ionization detector.

PubMed

Amanzadeh, Hatam; Yamini, Yadollah; Moradi, Morteza; Asl, Yousef Abdossalmi

2016-09-23

In the current study, a graphene/polyvinylchloride nanocomposite was successfully coated on a stainless steel substrate by a simple dip coating process and used as a novel headspace solid phase microextraction (HS-SPME) fiber for the extraction of phthalate esters (PEs) from drinking water and edible vegetable oil samples. The prepared SPME fibers exhibited high extractability for PEs (due to the dominant role of π-π stacking interactions and hydrophobic effects) yielding good sensitivity and precision when followed by a gas chromatograph with a flame ionization detector (GC-FID). The optimization strategy of the extraction process was carried out using the response surface method based on a central composite design. The developed method gave a low limit of detection (0.06-0.08μgL(-1)) and good linearity (0.2-100μgL(-1)) for the determination of the PEs under the optimized conditions (extraction temperature, 70±1°C; extraction time, 35min; salt concentration, 30% w/v; stirring rate, 900rpm; desorption temperature, 230°C; and desorption time, 4min) whereas the repeatability and fiber-to-fiber reproducibility were in the range 6.1-7.8% and 8.9-10.2%, respectively. Finally, the proposed method was successfully applied to the analysis of PEs in drinking water and edible oil samples with good recoveries (87-112%) and satisfactory precisions (RSDs<8.3%), indicating the absence of matrix effects in the proposed HS-SPME method. Copyright © 2016 Elsevier B.V. All rights reserved.

Spectral imaging and passive sampling to investigate particle sources in urban desert regions.

PubMed

Wagner, Jeff; Casuccio, Gary

2014-07-01

Two types of electron microscopy analyses were employed along with geographic information system (GIS) mapping to investigate potential sources of PM2.5 and PM10 (airborne particulate matter smaller than 2.5 and 10 μm, respectively) in two urbanized desert areas known to exhibit PM excursions. Integrated spectral imaging maps were obtained from scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) analyses of 13 filters collected in Imperial Valley, California. Seven were from 24 h PM10 Federal Reference Method (FRM) samplers and six were from PM2.5 FRM samplers. This technique enabled extraction of information from particles collected on complex filter matrices, and indicated that all samples exhibited substantial proportions of crustal particles. Six Imperial PM2.5 and PM10 filters selected from unusually high-PM days exhibited more large particles (2.5-15 and 10-30 μm, respectively) than did filters from low-PM days, and were more consistent with soils analyzed from the region. High winds were present on three of the six high-PM days. One of the high-PM2.5 filters also exhibited substantial fine carbonaceous soot PM, suggesting significant contributions from a combustion source. Computer-controlled SEM/EDS (CCSEM/EDS) was conducted on PM collected with UNC Passive samplers from Phoenix, Arizona. The passive samplers showed good agreement with co-located FRM PM10 and PM2.5 measurements (μg m(-3)), and also enabled detailed individual particle analysis. The CCSEM/EDS data revealed mostly crustal particles in both the Phoenix fine and coarse PM10 fractions. GIS maps of multiple dust-related parameters confirm that both Imperial Valley and Phoenix possess favorable conditions for airborne crustal PM from natural and anthropogenic sources.

Gold nanoparticle-embedded silk protein-ZnO nanorod hybrids for flexible bio-photonic devices

NASA Astrophysics Data System (ADS)

Gogurla, Narendar; Kundu, Subhas C.; Ray, Samit K.

2017-04-01

Silk protein has been used as a biopolymer substrate for flexible photonic devices. Here, we demonstrate ZnO nanorod array hybrid photodetectors on Au nanoparticle-embedded silk protein for flexible optoelectronics. Hybrid samples exhibit optical absorption at the band edge of ZnO as well as plasmonic energy due to Au nanoparticles, making them attractive for selective UV and visible wavelength detection. The device prepared on Au-silk protein shows a much lower dark current and a higher photo to dark-current ratio of ∼105 as compared to the control sample without Au nanoparticles. The hybrid device also exhibits a higher specific detectivity due to higher responsivity arising from the photo-generated hole trapping by Au nanoparticles. Sharp pulses in the transient photocurrent have been observed in devices prepared on glass and Au-silk protein substrates due to the light induced pyroelectric effect of ZnO, enabling the demonstration of self-powered photodetectors at zero bias. Flexible hybrid detectors have been demonstrated on Au-silk/polyethylene terephthalate substrates, exhibiting characteristics similar to those fabricated on rigid glass substrates. A study of the performance of photodetectors with different bending angles indicates very good mechanical stability of silk protein based flexible devices. This novel concept of ZnO nanorod array photodetectors on a natural silk protein platform provides an opportunity to realize integrated flexible and self-powered bio-photonic devices for medical applications in near future.

Foam injection molding of elastomers with iron microparticles

NASA Astrophysics Data System (ADS)

Volpe, Valentina; D'Auria, Marco; Sorrentino, Luigi; Davino, Daniele; Pantani, Roberto

2015-12-01

In this work, a preliminary study of foam injection molding of a thermoplastic elastomer, Engage 8445, and its microcomposite loaded with iron particles was carried out, in order to evaluate the effect of the iron microparticles on the foaming process. In particular, reinforced samples have been prepared by using nanoparticles at 2% by volume. Nitrogen has been used as physical blowing agent. Foamed specimens consisting of neat and filled elastomer were characterized by density measurements and morphological analysis. While neat Engage has shown a well developed cellular morphology far from the injection point, the addition of iron microparticles considerably increased the homogeneity of the cellular morphology. Engage/iron foamed samples exhibited a reduction in density greater than 32%, with a good and homogeneous cellular morphology, both in the transition and in the core zones, starting from small distances from the injection point.

Optically stimulated luminescence of natural NaCl mineral from Dead Sea exposed to gamma radiation.

PubMed

Roman-Lopez, J; Piña López, Y I; Cruz-Zaragoza, E; Marcazzó, J

2018-08-01

In this work, the continuous wave - optically stimulated luminescence (CW-OSL) emissions of natural salt minerals, collected from Dead Sea in summer of 2015, were studied. The CW-OSL dose response of natural salt showed a linear range between 0.5Gy and 10Gy of gamma radiation of 60 Co. Samples exposed at 3Gy exhibited good repeatability with a variation coefficient of 4.6%. The CW-OSL response as function of the preheating temperature (50-250°C) was analyzed. An increase of 15% of the CW-OSL response was observed in NaCl samples during storage period of 336h. The results showed that the natural Dead Sea salt minerals could be applied as natural dosimeter of gamma radiation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Facile synthesis of titanium (IV) ion immobilized adenosine triphosphate functionalized silica nanoparticles for highly specific enrichment and analysis of intact phosphoproteins.

PubMed

Wang, Hao; Tian, Zhixin

2018-06-06

Analysis of phosphoproteins always faces the challenge of low stoichiometry, which demands highly selective and efficient enrichment in the initial sample preparation. Here we report our synthesis of the novel titanium (IV) ion immobilized adenosine triphosphate functionalized silica nanoparticles (Ti 4+ -ATP-NPs) for efficient enrichment of intact phosphoproteins. The average diameter of Ti 4+ -ATP-NPs was about 128 nm with good dispersibility and the saturated adsorption capacity for β-casein was 1046.5 mg/g. In addition, Ti 4+ -ATP-NPs exhibited high specificity and selectivity in enriching phosphoproteins from both standard protein mixtures and complex biological samples (non-fat milk, chicken egg white and mouse heart tissue extract) as demonstrated by SDS-PAGE. Copyright © 2018 Elsevier B.V. All rights reserved.

Comparison of dry sliding wear and friction behavior of Al6061/SiC PMMC with Al6061 alloy

NASA Astrophysics Data System (ADS)

Murthy, A. G. Shankara; Mehta, N. K.; Kumar, Pradeep

2018-04-01

Dry sliding wear and friction behavior tests were conducted on Al6061 alloy and Al6061/SiC particle reinforced metal matrix composites (PMMCs) reinforced with fine particles of 5, 10 and 15 µm size having 5,7.5 and 10% weight content fabricated by stir-casting route. Cylindrical sample pins produced as per ASTM standard were tested for various parameters like SiC size, weight content, load and sliding distance affecting the wear rate or resistance and friction. Results indicated that Al6061/SiCp composites exhibited good wear resistance compared to Al6061 alloy for the tested parameters.

Properties of nanosheets of 2D-borocarbonitrides related to energy devices, transistors and other areas

NASA Astrophysics Data System (ADS)

Sreedhara, M. B.; Gopalakrishnan, K.; Bharath, B.; Kumar, Ram; Kulkarni, G. U.; Rao, C. N. R.

2016-07-01

We have prepared borocarbonitrides of various compositions with extended sheet morphology, by the reaction of few-layer graphene with boric acid and urea at 900 °C and characterized them in detail. Supercapacitor performance of the borocarbonitrides has been studied in detail, the composition containing more pyridinc nitrogen exhibiting a specific capacitance of 306 F/g at 0.2 A/g. This composition also shows good oxygen reduction reaction (ORR) activity with an electron transfer number close to 4. The extended sheet structures of the BxCyNz samples has enabled us to fabricate field-effect transistors. These materials also show reasonable UV photoresponse.

Determination of binding-dioxygen in dioxygen complexes by headspace gas chromatography.

PubMed

Wang, Wei; Feng, Shun; Li, Ya-ni; Wu, Meiying; Wang, Jide

2008-06-06

Dioxygen complexes play important roles in organisms' bodies, so the determination of binding-dioxygen has practical significance. A simple and robust method based on headspace gas chromatography was proposed to determine the binding-dioxygen in dioxygen complexes. By measuring the content change of nitrogen gas in a vial, the amount of oxygen released from dixoygen complexes can be determined. The method was validated using potassium chlorate as model sample, and the results exhibited good recoveries (90-99%) with the relative standard deviation less than 8%. It was also used to analyze dioxygen complex of cobalt bis(salicylaldehyde) ethylenediimine and polyamine cobalt complexes prepared by solid-phase reaction.

Reflexion on linear regression trip production modelling method for ensuring good model quality

NASA Astrophysics Data System (ADS)

Suprayitno, Hitapriya; Ratnasari, Vita

2017-11-01

Transport Modelling is important. For certain cases, the conventional model still has to be used, in which having a good trip production model is capital. A good model can only be obtained from a good sample. Two of the basic principles of a good sampling is having a sample capable to represent the population characteristics and capable to produce an acceptable error at a certain confidence level. It seems that this principle is not yet quite understood and used in trip production modeling. Therefore, investigating the Trip Production Modelling practice in Indonesia and try to formulate a better modeling method for ensuring the Model Quality is necessary. This research result is presented as follows. Statistics knows a method to calculate span of prediction value at a certain confidence level for linear regression, which is called Confidence Interval of Predicted Value. The common modeling practice uses R2 as the principal quality measure, the sampling practice varies and not always conform to the sampling principles. An experiment indicates that small sample is already capable to give excellent R2 value and sample composition can significantly change the model. Hence, good R2 value, in fact, does not always mean good model quality. These lead to three basic ideas for ensuring good model quality, i.e. reformulating quality measure, calculation procedure, and sampling method. A quality measure is defined as having a good R2 value and a good Confidence Interval of Predicted Value. Calculation procedure must incorporate statistical calculation method and appropriate statistical tests needed. A good sampling method must incorporate random well distributed stratified sampling with a certain minimum number of samples. These three ideas need to be more developed and tested.

Measuring the bias against low-income country research: an Implicit Association Test.

PubMed

Harris, Matthew; Macinko, James; Jimenez, Geronimo; Mullachery, Pricila

2017-11-06

With an increasing array of innovations and research emerging from low-income countries there is a growing recognition that even high-income countries could learn from these contexts. It is well known that the source of a product influences perception of that product, but little research has examined whether this applies also in evidence-based medicine and decision-making. In order to examine likely barriers to learning from low-income countries, this study uses established methods in cognitive psychology to explore whether healthcare professionals and researchers implicitly associate good research with rich countries more so than with poor countries. Computer-based Implicit Association Test (IAT) distributed to healthcare professionals and researchers. Stimuli representing Rich Countries were chosen from OECD members in the top ten (>$36,000 per capita) World Bank rankings and Poor Countries were chosen from the bottom thirty (<$1000 per capita) countries by GDP per capita, in both cases giving attention to regional representation. Stimuli representing Research were descriptors of the motivation (objective/biased), value (useful/worthless), clarity (precise/vague), process (transparent/dishonest), and trustworthiness (credible/unreliable) of research. IAT results are presented as a Cohen's d statistic. Quantile regression was used to assess the contribution of covariates (e.g. age, sex, country of origin) to different values of IAT responses that correspond to different levels of implicit bias. Poisson regression was used to model dichotomized responses to the explicit bias item. Three hundred twenty one tests were completed in a four-week period between March and April 2015. The mean Implicit Association Test result (a standardized mean relative latency between congruent and non-congruent categories) for the sample was 0.57 (95% CI 0.52 to 0.61) indicating that on average our sample exhibited moderately strong implicit associations between Rich Countries and Good Research. People over 40 years of age were less likely to exhibit pro-poor implicit associations, and being a peer reviewer contributes to a more pro-poor association. The majority of our participants associate Good Research with Rich Countries, compared to Poor Countries. Implicit associations such as these might disfavor research from poor countries in research evaluation, evidence-based medicine and diffusion of innovations.

Fully Printed Flexible and Stretchable Electronics

NASA Astrophysics Data System (ADS)

Zhang, Suoming

Through this thesis proposal, the author has demonstrated series of flexible or stretchable sensors including strain gauge, pressure sensors, display arrays, thin film transistors and photodetectors fabricated by a direct printing process. By adopting the novel serpentine configuration with conventional non-stretchable materials silver nanoparticles, the fully printed stretchable devices are successfully fabricated on elastomeric substrate with the demonstration of stretchable conductors that can maintain the electrical properties under strain and the strain gauge, which could be used to measure the strain in desired locations and also to monitor individual person's finger motion. And by investigating the intrinsic stretchable materials silver nanowires (AgNWs) with the conventional configuration, the fully printed stretchable conductors are achieved on various substrates including Si, glass, Polyimide, Polydimethylsiloxane (PDMS) and Very High Bond (VHB) tape with the illustration of the capacitive pressure sensor and stretchable electroluminescent displays. In addition, intrinsically stretchable thin-film transistors (TFTs) and integrated logic circuits are directly printed on elastomeric PDMS substrates. The printed devices utilize carbon nanotubes and a type of hybrid gate dielectric comprising PDMS and barium titanate (BaTiO3) nanoparticles. The BaTiO3/PDMS composite simultaneously provides high dielectric constant, superior stretchability, low leakage, as well as good printability and compatibility with the elastomeric substrate. Both TFTs and logic circuits can be stretched beyond 50% strain along either channel length or channel width directions for thousands of cycles while showing no significant degradation in electrical performance. Finally, by applying the SWNTs as the channel layer of the thin film transistor, we successfully fabricate the fully printed flexible photodetector which exhibits good electrical characteristics and the transistors exhibit good reliability under bending conditions owing to the ultrathin polyimide substrate as well as the superior mechanical flexibility of the gate dielectric and carbon nanotube network. Furthermore, we have demonstrated that by using two types of SWCNT samples with different optical absorption characteristics, the photoresponse exhibits unique wavelength selectivity, as manifested by the good correlation between the responsive wavelengths of the devices with the absorption peaks of the corresponding carbon nanotubes. All the proposed materials above together with the unique direct printing process may offer an entry into more sophisticated flexible or stretchable electronic systems with monolithically integrated sensors, actuators, and displays for real life applications.

Characterization of porous nickel-titanium alloys for medical applications

NASA Astrophysics Data System (ADS)

Hernandez Tenorio, Rommy

The purpose of this study is to investigate the electrochemical behaviour of porous NiTi alloys provided by different sources. In order to achieve this goal, a systematic characterization of the physical and chemical properties by different techniques and new approaches were conducted. The martensite-austenite phase transition was determined by the use of the Differential scanning Calorimetry (DSC). The morphological characteristics (porosity and roughness) were measured with the Scanning Electron Microscopy (SEM). The surface chemical composition of the samples was identified by the use of X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). In the case of porous material the biomechanical compatibility is closely related to the porosity distribution of the sample. To describe appropriately the influence of this parameter on the properties of NiTi, four types of materials provided by different sources were analyzed. The samples were produced by Self-propagating High-temperature Synthesis (SHS) procedure. A heat treatment was applied in order to release internal stress created during forming processes, one series of specimens from each type was submitted to an annealing process during 30 min at 550°C in an air atmosphere. Its influence on the properties of the materials was also evaluated. Our first results showed that despite the fact that all the materials present different pore size, all the samples exhibited an open and interconnected porosity that promotes a good fixation and bone ingrowth within their structure. The thermal analysis showed that the temperature of the inception of the martensite-austenite phase transition occurs at 60°C, which is greater than the body temperature by 20°C. The microscopic analysis for the samples revealed that the heat treatment did not generate any morphological changes. The XPS study indicated that the surface oxidation occurs after the heat treatment. This oxide layer has a different thickness for the materials in the range of 310--3990 A. The evaluation of the corrosion resistance of the four porous NiTi alloys showed a correlation between the chemical composition, pore size and the electrochemical behaviour. In particular it was found that the corrosion resistance is related to the surface chemical composition of the electrodes rather than to their surface morphology. First we observed that the impact of the annealing process varies with the type of sample. The non-treated samples showed higher breakdown potentials and also bigger pores. The materials with a pore size in the range of 80-120mum showed different behaviours, one material (B) showed no visible effect while the other two (A and C) exhibited a decrease of the breakdown potential value. The material with the smallest pore size 35-50mum showed an important improvement after the heat treatment. Therefore, we can conclude, that the surface treatment used in our investigations led to an improvement of the corrosion resistance for small pores whereas a decrease was observed for bigger pores. On the other hand the lower corrosion rates observed on treated samples are an indication of the high corrosion resistance compare to those non-treated. In this case we observed that the one material (B) exhibited the highest corrosion rate presented a difference in the chemical composition as shown by XPS analysis. Moreover, the absence of intermediate titanium oxides (Ti2+ and Ti3+) was observed. As these oxides were identified in the other materials (A, C and D) we conclude that the presence of intermediate titanium oxides on surface chemical composition of the samples results on better corrosion rates and improved corrosion resistance. The Spectroelectrochemistry evaluation showed that solid electropolished sample and solid mechanopolished samples exhibited a better corrosion resistance than porous mechanopolished samples. However the solid mechanopolished sample exhibits a higher corrosion rate almost as high as the one showed by the porous sample. On the other hand a higher breakdown potential was measured porous samples compared to previous studies. However this sample shows a higher susceptibility for pitting and crevice corrosion. This can be explained by the porous structure of the sample. The FTIR results showed the interactions between the solution and the samples. It can be observed that each sample exhibit a particular behaviour. The porous sample as well as the solid samples showed Ti-OH interactions. Moreover both solid samples exhibited another peak corresponding to the OTi(OH)CCH interaction, which is explained by the chemical composition of the electrolyte, in this case the Hank's solution that has a certain amount of glucose. However an inversion of the peak is observed in both samples, this direction change can be attributed to the surface treatment. The electropolished sample showed a more stable behaviour mean while the mechanopolished sample exhibited a change during the reverse scan. (Abstract shortened by UMI.)

[Determination of heavy metals for RoHS compliance by ICP-OES spectrometry coupled with microwave extraction system].

PubMed

Hua, Li; Wu, Yi-Ping; An, Bing; Lai, Xiao-Wei

2008-11-01

The harm of heavy metals contained in electronic and electrical equipment (EEE) on environment is of high concern by human. Aiming to handle the great challenge of RoHS compliance, the determinations of trace or ultratrace chromium (Cr), cadmium (Cd), mercury (Hg) and lead (Pb) by inductively coupled plasma optical emission spectrometry (ICP-OES) was performed in the present paper, wherein, microwave extraction technology was used to prepare the sample solutions. In addition, the precision, recovery, repeatability and interference issues of this method were also discussed. The results exhibited that using the microwave extraction system to prepare samples is more quick, lossless, contamination-free in comparison with the conventional extraction methods such as dry ashing, wet-oven extraction etc. By analyzing the recoveries of these four heavy metals over different working time and wavelengths, the good recovery range between 85% and 115% showed that there was only tiny loss or contamination during the process of microwave extraction, sample introduction and ICP detection. Repeatability experiments proved that ICP plasma had a good stability during the working time and the matrix effect was small. Interference was a problem troublesome for atomic absorption spectrometry (AAS), however, the techniques of standard additions or inter-element correction (IEC) method can effectively eliminated the interferences of Ni, As, Fe etc. with the Cd determination. By employing the multi-wavelengths and two correction point methods, the issues of background curve sloping shift and spectra overlap were successfully overcome. Besides, for the determinations of trace heavy metal elements, the relative standard deviation (RSD) was less than 3% and the detection limits were less than 1 microg x L(-10 (3sigma, n = 5) for samples, standard solutions, and standard additions, which proved that ICP-OES has a good precision and high reliability. This provided a reliable technique support for electronic and electrical (EE) industries to comply with RoHS directive.

A combination of computational-experimental study on metal-organic frameworks MIL-53(Al) as sorbent for simultaneous determination of estrogens and glucocorticoids in water and urine samples by dispersive micro-solid-phase extraction coupled to UPLC-MS/MS.

PubMed

Gao, Guihua; Li, Sijia; Li, Shuo; Wang, Yudan; Zhao, Pan; Zhang, Xiangyu; Hou, Xiaohong

2018-04-01

In this work, computational and experimental methods were used to study the adsorption of estrogens and glucocorticoids on metal-organic frameworks (MOFs). Computer-aided molecular simulation was applied to predict the adsorption of eight analytes on four MOFs (MIL-101(Cr), MIL-100(Fe), MIL-53(Al), and UiO-66(Zr)) by examining molecular interactions and calculating free binding energies. Subsequently, the four water-stable MOFs were synthesized and evaluated as adsorbents for the target hormones in aqueous solution. As the MOF exhibiting the highest adsorption capacity in both computations and experiments, MIL-53(Al) was chosen as a sorbent to develop a dispersive micro-solid-phase extraction procedure coupled to ultra-performance liquid chromatography tandem mass spectrometry for simultaneous determination of the target analytes in water and human urine samples. Experimental parameters affecting the extraction recoveries, including pH, ionic strength, MIL-53(Al) amount, extraction time, desorption time, and desorption solvent, were optimized. The optimized method provided a linear range of 0.005025-368.6μg/L with good correlation coefficients (0.9982 ≤ r 2 ≤ 0.9992), and limits of detection (S/N = 3) and quantification (S/N = 10) of 0.0015-1.0μg/L and 0.005-1.8μg/L, respectively. The analyte recoveries were in the range of 80.6-98.4% in water samples and 88.4-93.2% in urine samples. Furthermore, MIL-53(Al) showed good stability over 10 extraction cycles (RSD < 10.0%). Good agreement between experimental measurements and computational results showed the potential of this approach for elucidating adsorption mechanisms and predicating extraction efficiencies for MOFs and targets, providing new directions for the development and utilization of MOFs. Copyright © 2017 Elsevier B.V. All rights reserved.

Dosimetric properties of germanium doped calcium borate glass subjected to 6 MV and 10 MV X-ray irradiations

NASA Astrophysics Data System (ADS)

Tengku Kamarul Bahri, T. N. H.; Wagiran, H.; Hussin, R.; Saeed, M. A.; Hossain, I.; Ali, H.

2014-10-01

Germanium doped calcium borate glasses are investigated in term of thermoluminescence properties to seek their possibility to use as glass radiation dosimeter. The samples were exposed to 6 MV, and 10 MV photon beams in a dose range of 0.5-4.0 Gy. There is a single and broad thermoluminescence glow curve that exhibits its maximum intensity at about 300 °C. Linear dose response behavior has been found in this dose range for the both photon energies. Effective atomic number, TL sensitivity, and reproducibility have also been studied. It is found that the sensitivity of germanium doped sample at 6 MV is only 1.28% and it is superior to the sensitivity at 10 MV. The reproducibility of germanium doped sample is good with a percentage of relative error less than 10%. The results indicate that this glass has a potential to be used as a radiation dosimetry, especially for application in radiotherapy.

Effect of annealing on the structural and optical properties of TiO2 powder prepared by sol-gel route

NASA Astrophysics Data System (ADS)

Halder, Nilanjan; Misra, Kamakhya Prakash

2016-05-01

Using titanium isopropoxide as the precursor, Titanium dioxide (TiO2) powder was synthesized via sol-gel method, a promising low temperature route for preparing nanosized metal oxide semiconductors with good homogeneity at low cost. The as-prepared nano powder was thermally treated in air at 550, 650, 750, 900 and 1100°C for 1hr after drying at room temperature and used for further characterization. X-ray diffraction measurements showed that the annealing treatment has a strong impact on the crystal phase of TiO2 samples. The crystallite size as calculated from Debye Scherer formula lies in the range 29-69 nm and is found to increase with increase in annealing temperature. Photoluminescence studies exhibit an improvement in the optical efficiency of the samples with post synthesis heat treatment. Annealing at temperature above 900°C results in a degradation of the structural and optical quality of the TiO2 nano powder samples.

Dibenzo-p-dioxins and dibenzofurans in human breast milk collected in the area of Taranto (Southern Italy): first case study.

PubMed

Bianco, Giuliana; Zianni, Rosalia; Anzillotta, Giuseppe; Palma, Achille; Vitacco, Vincenzo; Scrano, Laura; Cataldi, Tommaso R I

2013-03-01

We report on the content of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in 15 breast milk samples of nursing women living in the city of Taranto (Southern, Italy) or nearby. Breast milk samples were collected over the 2008-2009 period and analyzed by gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS) upon accelerated solvent extraction (ASE) using acetone/n-hexane mixture 1:1 (v/v). The method was validated demonstrating good performing features. Profiles of PCDD/PCDF congeners in breast milk samples exhibited a prevalence of PCDFs compared to PCDDs. Toxic equivalents (TEQs in picogram per gram fat) of four breast milk were far above the legal limit for human consumption of 3.0 pg/g; their estimated daily and weekly dietary intake were almost 5-20 and 10-40 times higher, respectively, than the tolerable intake values established by the World Health Organization.

Dispersion Morphology of Poly(methyl acrylate)/Silica Nanocomposites

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

D Janes; J Moll; S Harton

Nearly monodisperse poly(methyl acrylate) (PMA) and spherical SiO{sub 2} nanoparticles (NP, d = 14 {+-} 4 nm) were co-cast from 2-butanone, a mutually good solvent and a displacer of adsorbed PMA from silica. The effects of NP content and post-casting sample history on the dispersion morphology were found by small-angle X-ray scattering supplemented by transmission electron microscopy. Analysis of the X-ray results show that cast and thermally annealed samples exhibited a nearly random particle dispersion. That the same samples, prior to annealing, were not well-dispersed is indicative of thermodynamic miscibility during thermal annealing over the range of NP loadings studied.more » A simple mean-field thermodynamic model suggests that miscibility results primarily from favorable polymer segment/NP surface interactions. The model also indicates, and experiments confirm, that subsequent exposure of the composites to the likely displacer ethyl acetate results in entropic destabilization and demixing into NP-rich and NP-lean phases.« less

Hair as a specimen to document tetramethylene disulfotetramine exposure.

PubMed

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

2012-05-01

Tetramethylene disulfotetramine (tetramine) is a rodenticide that has been banned for many years in China. Since 2005, inhabitants of a village in the Henan Province have been suffering from grand mal seizures. To investigate the possibility of tetramine as the cause, we developed a method to determine tetramine in human hair. Sample preparation involved external decontamination, frozen pulverization, and ultrasonication in 2 mL ethyl acetate in the presence of cocaine-d3 as an internal standard. The method exhibited good linearity; calibration curve was linear over a range of 0.1-20 ng/mg hair. The limit of detection for the assay was 0.05 ng/mg hair. Except for one subject (No. 4), all head and pubic hair samples were positive for tetramine. The concentrations of tetramine in pubic hair were significantly higher than those in the same subjects' head hair samples. Because of a long retention in body, segmental head hair analysis cannot provide an accurate exposure history of tetramine in the body. © 2012 American Academy of Forensic Sciences.

Development of a pH sensing membrane electrode based on a new calix[4]arene derivative.

PubMed

Kormalı Ertürün, H Elif; Demirel Özel, Ayça; Sayın, Serkan; Yılmaz, Mustafa; Kılıç, Esma

2015-01-01

A new pH sensing poly(vinyl chloride) (PVC) membrane electrode was developed by using recently synthesized 5,17-bis(4-benzylpiperidine-1-yl)methyl-25,26,27,28-tetrahydroxy calix[4]arene as an ionophore. The effects of membrane composition, inner filling solution and conditioning solution on the potential response of the proposed pH sensing membrane electrode were investigated. An optimum membrane composition of 3% ionophore, 67% o-nitrophenyl octyl ether (o-NPOE) as plasticizer, 30% PVC was found. The electrode exhibited a near-Nernstian slope of 58.7±1.1 mV pH(-1) in the pH range 1.9-12.7 at 20±1 °C. It showed good selectivity for H(+) ions in the presence of some cations and anions and a longer lifetime of at least 12 months when compared with the other PVC membrane pH electrodes reported in the literature. Having a wide working pH range, it was not only applied as a potentiometric indicator electrode in various acid-base titrations, but also successfully employed in different real samples. It has good reproducibility and repeatability with a response time of 6-7s. Compared to traditional glass pH electrode, it exhibited excellent potentiometric response after being used in fluoride-containing media. Copyright © 2014 Elsevier B.V. All rights reserved.

Optimum Conditions for Preparation of High-Performance (Ba0.97Ca0.03)(Ti0.94Sn0.06)O3 Ceramics by Solid-State Combustion

NASA Astrophysics Data System (ADS)

Chootin, Suphornphun; Bongkarn, Theerachai

2017-08-01

The effects of calcination conditions (950°C to 1200°C for 2 h to 6 h) and sintering temperature (1300°C to 1500°C for 2 h) on phase formation, microstructure, and electrical behavior of lead-free piezoelectric (Ba0.97Ca0.03)(Ti0.94Sn0.06)O3 (BCTS) ceramics produced by solid-state combustion using glycine as fuel have been investigated. BCTS powder with pure perovskite structure was obtained by calcination at 1100°C for 4 h. The microstructure of the BCTS powders showed almost spherical shape with average particle size increasing from 184 nm to 320 nm as the calcination temperature and soaking time were increased. The XRD patterns of all ceramics exhibited single perovskite structure. Rietveld refinement analysis indicated that the BCTS ceramics exhibited coexistence of orthorhombic and tetragonal phase in all samples with increased tetragonal phase content with increasing sintering temperature. The average grain size, density, dielectric constants at room ( ɛ r) and Curie temperature ( ɛ C), remanent polarization ( P r), and piezoelectric constant ( d 33) increased as the sintering temperature was increased up to 1400°C, then decreased. BCTS ceramic sintered at 1400°C exhibited the highest relative density (98%), highest dielectric response ( ɛ r = 4951, ɛ C = 19,185), good ferroelectric behavior ( P r = 12.74 μC/cm2 and coercive field E c = 1.60 kV/cm), and highest d 33 value (528 pC/N). The large piezoelectricity of BCTS ceramics makes them good candidates for use in lead-free applications to replace Pb-based ceramics.

Synthesis and characterization of a molecularly imprinted polymer for the determination of trace tributyltin in seawater and seafood by liquid chromatography-tandem mass spectroscopy.

PubMed

Zhu, Shanshan; Hu, Futao; Yang, Ting; Gan, Ning; Pan, Daodong; Cao, Yuting; Wu, Dazhen

2013-03-15

Analysis of tributyltin chloride (TBT) in environmental samples, such as seawater, is important in order to evaluate the TBT contamination and accumulation in the trophic chain. The environmental impact of organotin compounds has been a particular focus of analytical studies. The present study reports the use of molecular imprinting technology coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine trace amounts of TBT in seawater and seafood (mussel tissue samples). The imprinted polymer was synthesized by a non-covalent free-radical approach using acrylamide (AM) as a monomer and TBT as a template molecule in acetonitrile solvent (polymerization media). The imprinted polymer synthesized by this approach exhibited good adsorptive capacity and allowed specific retention of TBT. Recoveries of TBT in seawater samples spiked with different TBT concentrations ranged from 67.2% to 81.1% with peak area precision (RSD)<3.7%, and recoveries of TBT in mussel tissue samples ranged from 75.0% to 94.2% with RSD<4.8%. Copyright © 2013 Elsevier B.V. All rights reserved.

Physical-durable performance of concrete incorporating high loss on ignition-fly ash

NASA Astrophysics Data System (ADS)

Huynh, Trong-Phuoc; Ngo, Si-Huy; Hwang, Chao-Lung

2018-04-01

This study investigates the feasibility of using raw fly ash with a high loss on ignition in concrete. The fly ash-free concrete samples were prepared with different water-to-binder (w/b) ratios of 0.35, 0.40, and 0.45, whereas the fly ash concrete samples were prepared with a constant w/b of 0.40 and with various fly ash contents (10%, 20%, and 30%) as a cement substitution. The physical properties and durability performance of the concretes were evaluated through fresh concrete properties, compressive strength, strength efficiency of cement, ultrasonic pulse velocity, and resistance to sulfate attack. Test results show that the w/b ratio affected the concrete properties significantly. The incorporation of fly ash increased the workability and reduced the unit weight of fresh concrete. In addition, the fly ash concrete samples containing up to 20% fly ash exhibited an improved strength at long-term ages. Further, all of the fly ash concrete samples showed a good durability performance with ultrasonic pulse velocity value of greater than 4100 m/s and a comparable sulfate resistance to the no-fly ash concrete.

Development of a Method for the Determination of Chromium and Cadmium in Tannery Wastewater Using Laser-Induced Breakdown Spectroscopy

PubMed Central

Bukhari, Mahwish; Awan, M. Ali; Qazi, Ishtiaq A.; Baig, M. Anwar

2012-01-01

This paper illustrates systematic development of a convenient analytical method for the determination of chromium and cadmium in tannery wastewater using laser-induced breakdown spectroscopy (LIBS). A new approach was developed by which liquid was converted into solid phase sample surface using absorption paper for subsequent LIBS analysis. The optimized values of LIBS parameters were 146.7 mJ for chromium and 89.5 mJ for cadmium (laser pulse energy), 4.5 μs (delay time), 70 mm (lens to sample surface distance), and 7 mm (light collection system to sample surface distance). Optimized values of LIBS parameters demonstrated strong spectrum lines for each metal keeping the background noise at minimum level. The new method of preparing metal standards on absorption papers exhibited calibration curves with good linearity with correlation coefficients, R2 in the range of 0.992 to 0.998. The developed method was tested on real tannery wastewater samples for determination of chromium and cadmium. PMID:22567570

Rapid analysis of ultraviolet filters using dispersive liquid-liquid microextraction coupled to headspace gas chromatography and mass spectrometry.

PubMed

Pierson, Stephen A; Trujillo-Rodríguez, María J; Anderson, Jared L

2018-05-29

An ionic-liquid-based in situ dispersive liquid-liquid microextraction method coupled to headspace gas chromatography and mass spectrometry was developed for the rapid analysis of ultraviolet filters. The chemical structures of five ionic liquids were specifically designed to incorporate various functional groups for the favorable extraction of the target analytes. Extraction parameters including ionic liquid mass, molar ratio of ionic liquid to metathesis reagent, vortex time, ionic strength, pH, and total sample volume were studied and optimized. The effect of the headspace temperature and volume during the headspace sampling step was also evaluated to increase the sensitivity of the method. The optimized procedure is fast as it only required ∼7-10 min per extraction and allowed for multiple extractions to be performed simultaneously. In addition, the method exhibited high precision, good linearity, and low limits of detection for six ultraviolet filters in aqueous samples. The developed method was applied to both pool and lake water samples attaining acceptable relative recovery values. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Getting-Out-of-Bed (GoB) Scale: A Measure of Motivation and Life Outlook in Older Adults with Cancer

PubMed Central

Clough-Gorr, Kerri M.; Rakowski, William; Clark, Melissa; Silliman, Rebecca A.

2009-01-01

Objective To develop and evaluate the psychometric properties of a measure of motivation and life outlook (Getting-Out-of-Bed [GoB]). Design Secondary analysis of baseline and 6-month data from a longitudinal follow-up study of older breast cancer survivors. Participants Women (N=660) diagnosed with primary breast cancer stage I -IIIA disease, age ≥65-years, and permission to contact from an attending physician in four geographic regions in the USA (city-based Los Angeles, California; state-wide in Minnesota, North Carolina, and Rhode Island). Measurement Data were collected over 6-months of follow-up from consenting patients’ medical records and telephone interviews with patients. Data collected included the 4-item GoB, health related quality of life (HRQoL), breast cancer, socio-demographic and health-related characteristics. Results Factor analysis produced, as hypothesized, one principal component with eigen values of 2.74baseline and 2.916-months which explained 68.6%baseline and 72.7%6-months of total variance. In further psychometric analyses, GoB exhibited good construct validity (divergent: low non-statistically significant correlations with unrelated constructs; convergent: moderate statistically significant correlations with related constructs; discriminant: distinguished high HRQoL groups with a high level of significance), excellent internal reliability (Cronbach’s alpha 0.84baseline,0.876-months), and produced stable measurements over 6-months. Women with GoB scores ≥50 at baseline were more likely at 6-months to have good HRQoL, good self-perceived health, and report regular exercise, indicating good predictive ability. Conclusion GoB demonstrated overall good psychometric properties in this sample of older breast cancer survivors, suggestive of a promising tool for assessing motivation and life outlook in older adults. Nevertheless, because it was developed and initially evaluated in a select sample, using measures with similar but not exact content overlap further evaluation is needed before it can be recommended for widespread use. PMID:19813135

Psychosocial determinants of intention to screen for Alzheimer disease

PubMed Central

Galvin, James E.; Fu, Qiang; Nguyen, Joseph T.; Glasheen, Cristie; Scharff, Darcell P.

2008-01-01

Background There is little information about how receptive older adults are to discuss memory problems with healthcare providers. Here we test the psychosocial factors explaining older adults’ intention to undergo screening for Alzheimer disease (AD). Methods A population-based, random-digit dialing strategy surveyed 1039 older adults. The Behavioral Model of Health Services Use was used as a conceptual framework for a questionnaire testing constructs from several behavioral theories. Structural equation modeling assessed the relationship of latent variables to each construct with goodness-of-fit indices. Results The study had an 82% response rate and 72% completer rate. The respondents’ mean age was 62.7 ± 10.2 y (range 50–97). The sample was 67% women, 86% were Caucasian and less than 40% had personal experience with AD. Respondents were nondemented (Short Blessed scores = 1.7 ± 2.2). Predictors of intention to screen included perceived benefits (γ=.35), knowledge of dementia (γ=.26), self-efficacy (γ=.23), preventive health behaviors (γ=.17), and perceived susceptibility (γ=.14). Knowledge was positively correlated with perceived benefits (φ=.29) and susceptibility (φ=.20). Preventive behaviors (φ=.20) were positively correlated with perceived benefits. Self-efficacy correlated positively with preventive behaviors (φ=.24) and perceived benefits (φ=.37) and negatively with perceived susceptibility (φ=−.11). Goodness-of-fit indices suggested a good fit of this model (RMSEA =.037, CFI = 0.98, RFI = .96). Discussion Older adults who have knowledge of dementia and perceive benefit from diagnosis and treatment are more likely to exhibit willingness and confidence to be tested for cognitive problems. Individuals with high self-efficacy, perceived susceptibility and positive preventive health behaviors are also more likely to exhibit intention. These constructs can now be used to develop interventions to evaluate cognitive health in the elderly. PMID:18790462

Development and Validation of a Novel LC-MS/MS Opioid Confirmation Assay: Evaluation of β-glucuronidase Enzymes and Sample Cleanup Methods.

PubMed

Yang, He S; Wu, Alan H B; Lynch, Kara L

2016-06-01

With the rise in the use and misuse of prescription opioids, there is an increasing need for the confirmed identification of opioid analgesics in toxicology laboratories. The goals of this study were to (i) systematically evaluate the hydrolysis efficiency of four β-glucuronidase enzymes under optimized condition; (ii) evaluate compound recovery, matrix effects and precision of three protein precipitation plates and (iii) develop and validate a qualitative liquid-chromatography mass spectrometry (LC-MS/MS) assay to identify 13 opioids in urine. A recombinant β-glucuronidase exhibited the best overall hydrolysis efficiency for seven opioid glucuronide conjugates compared with β-glucuronidase from red abalone, Escherichia coli and Patella vulgata One of the protein precipitation plates tested exhibited overall better recovery of the opioids and lower ion suppression compared with the other two plates. An ESI positive mode LC-MS/MS assay for qualitative opioid analysis was developed and validated. Linearity, LOD, precision, matrix effect, recovery, carryover and interference of the method were evaluated. Sixty-two patient samples were analyzed by both a legacy GC-MS opioid method and the LC-MS/MS method, and 22 samples were analyzed by the LC-MS/MS and an LC-MS/MS reference method. The results of the comparisons showed good concordance. Overall, we described an efficient sample preparation procedure for a sensitive qualitative opioid confirmation assay in urine. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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.

The Structural and Rank-Order Stability of Temperament in Young Children Based on a Laboratory-Observational Measure

PubMed Central

Dyson, Margaret W.; Olino, Thomas M.; Durbin, C. Emily; Goldsmith, H. Hill; Bufferd, Sara J.; Miller, Anna R.; Klein, Daniel N.

2015-01-01

It is generally assumed that temperament traits exhibit structural and rank-order stability over time. Most of the research on structural and rank-order stability has relied on parent-report measures. The present study used an alternative approach, a laboratory-observational measure (Laboratory Temperament Assessment Battery [Lab-TAB]), to examine the structural and rank-order stability of temperament traits in a community sample of young children (N = 447). Using structural equation modeling (SEM), we found that a similar five-factor structure consisting of the dimensions of Positive Affect/Interest, Sociability, Dysphoria, Fear/Inhibition, and Impulsivity vs. Constraint provided an adequate fit to the data at both age 3 and 6 years, suggesting good structural stability. Moreover, all five latent factors exhibited significant, albeit modest, rank-order stability from age 3 to 6. In addition, there were significant heterotypic associations of age 3 Sociability with age 6 PA/Interest, and age 3 Impulsivity vs. Constraint with age 6 Fear/Inhibition. PMID:25894709

Electrochemical detection of dopamine in the presence of ascorbic acid using PVP/graphene modified electrodes.

PubMed

Liu, Qin; Zhu, Xu; Huo, Zhaohui; He, Xulun; Liang, Yong; Xu, Maotian

2012-08-15

Graphene (GR) was synthesized through electrochemical reduction of graphene oxide and characterized by spectroscopic and electrochemical techniques. Polyvinylpyrrolidone (PVP)/graphene modified glassy carbon electrode (PVP/GR/GCE) was prepared and applied for the fabrication of dopamine (DA) sensors without the interference of ascorbic acid (AA). Compared to bare GCE, an increase of current signal was observed, demonstrating that PVP/GR/GCE exhibited favorable electron transfer kinetics and electrocatalytic activity towards the oxidation of dopamine. Furthermore, PVP/GR/GCE exhibited good ability to suppress the background current from large excess ascorbic acid. Amperometric response results show that the PVP based sensor displayed a wide linear range of 5×10(-10) to 1.13×10(-3) mol/L DA with a correlation coefficient of 0.9990 and a detection limit of 0.2 nM (S/N=3). The determination of dopamine in urine and human serum samples were studied. Copyright © 2012 Elsevier B.V. All rights reserved.

Rheological properties and baking performance of new oat beta-glucan-rich hydrocolloids.

PubMed

Lee, Suyong; Warner, Kathleen; Inglett, George E

2005-12-14

Two new oat beta-glucan hydrocolloids (designated C-trim20 and C-trim30) obtained through a thermal-shearing process were evaluated for their potential use in food products as functional ingredients. Their rheological characteristics were investigated using steady and dynamic shear measurements. Both samples exhibited typical shear-thinning and viscoelastic properties of random coil polysaccharides. The Cross equation was also used to examine the dependence of their apparent viscosity on shear rates. Furthermore, the effects of flour replacement with C-trim20 on the physical, rheological, and sensory properties of cookies were studied. The cookies containing C-trim20 exhibited reduced spreading characteristics compared with the control due to their increased elastic properties. Also, higher water content and water activity were observed in the C-trim20 cookies. However, flour replacement with C-trim20 up to 10% produced cookies with instrumental texture properties similar to those of the control, which was in good agreement with the sensory results.

Psychometric Evaluation of the Spiritual Coping Strategies Scale Arabic Version for Saudi Nursing Students.

PubMed

Cruz, Jonas Preposi; Alquwez, Nahed; Alqubeilat, Hikmet; Colet, Paolo C

2016-05-22

To evaluate the psychometric properties of the Spiritual Coping Strategies scale Arabic version (SCS-A) in a sample of nursing students in Saudi Arabia. This study had a cross-sectional design with a convenience sample of 100 nursing students in Saudi Arabia. Using the SCS-A and the Muslim Religiosity Scale for data collection, data were analyzed to establish the reliability and validity of the SCS-A. Good internal consistency reliability (Cronbach's α > .70) and stability reliability (intraclass correlation coefficient > .80) were observed. Two dominant factors were extracted from the scale items, the nonreligious coping strategies and religious coping strategies, which accounted for 35.5% and 32.7% of the variance, respectively. The religious coping subscale exhibited a strong positive correlation with the religious practices subscale of the Muslim Religious Involvement Scale (r = .45, p < .001) and total religiosity score (r = .48, p < .001) as well as a weak positive correlation with the intrinsic religious beliefs subscale (r = .25, p < .05). No significant relationship was found between nonreligious coping subscale and the Muslim Religious Involvement Scale. The SCS-A exhibited an acceptable validity and reliability, supporting its sound psychometric properties with respect to the responses from Saudi nursing students. © The Author(s) 2016.

Characterizing the Effect of Laser Power on Laser Metal Deposited Titanium Alloy and Boron Carbide

NASA Astrophysics Data System (ADS)

Akinlabi, E. T.; Erinosho, M. F.

2017-11-01

Titanium alloy has gained acceptance in the aerospace, marine, chemical, and other related industries due to its excellent combination of mechanical and corrosion properties. In order to augment its properties, a hard ceramic, boron carbide has been laser cladded with it at varying laser powers between 0.8 and 2.4 kW. This paper presents the effect of laser power on the laser deposited Ti6Al4V-B4C composites through the evolving microstructures and microhardness. The microstructures of the composites exhibit the formation of α-Ti phase and β-Ti phase and were elongated towards the heat affected zone. These phases were terminated at the fusion zone and globular microstructures were found growing epitaxially just immediately after the fusion zone. Good bondings were formed in all the deposited composites. Sample A1 deposited at a laser power of 0.8 kW and scanning speed of 1 m/min exhibits the highest hardness of HV 432 ± 27, while sample A4 deposited at a laser power of 2.0 kW and scanning speed of 1 m/min displays the lowest hardness of HV 360 ± 18. From the hardness results obtained, ceramic B4C has improved the mechanical properties of the primary alloy.

The effect of TiO2 coating on biological NiTi alloys after micro-arc oxidation treatment for corrosion resistance.

PubMed

Sukuroglu, Ebru Emine; Sukuroglu, Suleyman; Akar, Kubra; Totik, Yasar; Efeoglu, Ihsan; Arslan, Ersin

2017-08-01

NiTi alloys exhibit good properties, such as shape memory behavior, high corrosion resistant, having the closest elasticity modulus of a human bone and superior biocompatibility properties. However, the surface problems that arise during the use of this alloy limit the usage in the industry and health sector. In recent years, micro-arc oxidation method is used to improve the surface properties and increase the usage of these alloys. In this study, the TiO 2 coatings were deposited on the NiTi substrates. The surface topography, morphology, crystallographic structure, and thickness of the coatings were determined using scanning electron microscopy and X-ray diffraction. The corrosion properties were investigated using potentiostat test unit in two different media such as NaCl solution and simulated body fluid. The results show that the coated samples have higher corrosion resistance than uncoated samples in the two different media.

Rapid and Reliable Binding Affinity Prediction of Bromodomain Inhibitors: A Computational Study

PubMed Central

2016-01-01

Binding free energies of bromodomain inhibitors are calculated with recently formulated approaches, namely ESMACS (enhanced sampling of molecular dynamics with approximation of continuum solvent) and TIES (thermodynamic integration with enhanced sampling). A set of compounds is provided by GlaxoSmithKline, which represents a range of chemical functionality and binding affinities. The predicted binding free energies exhibit a good Spearman correlation of 0.78 with the experimental data from the 3-trajectory ESMACS, and an excellent correlation of 0.92 from the TIES approach where applicable. Given access to suitable high end computing resources and a high degree of automation, we can compute individual binding affinities in a few hours with precisions no greater than 0.2 kcal/mol for TIES, and no larger than 0.34 and 1.71 kcal/mol for the 1- and 3-trajectory ESMACS approaches. PMID:28005370

Comparison of quasistatic to impact mechanical properties of multiwall carbon nanotube/polycarbonate composites

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

Brühwiler, Paul A.; Barbezat, Michel; Necola, Adly

2010-10-22

We report the quasistatic tensile and impact penetration properties (falling dart test) of injection-molded polycarbonate samples, as a function of multiwall carbon nanotube (MWNT) concentration (0.0-2.5%). The MWNT were incorporated by dilution of a commercial MWNT/polycarbonate masterbatch. The stiffness and quasistatic yield strength of the composites increased approximately linearly with MWNT concentration in all measurements. The energy absorbed in fracture was, however, a negative function of the MWNT concentration, and exhibited different dependencies in quasistatic and impact tests. Small-angle x-ray scattering (SAXS) showed that the dispersion of the MWNT was similar at all concentrations. The negative effects on energy absorptionmore » are attributed to agglomerates remaining in the samples, which were observed in optical microscopy and SAXS. Overall, there was a good correspondence between static and dynamic energy absorption.« less

Support vector machines-based fault diagnosis for turbo-pump rotor

NASA Astrophysics Data System (ADS)

Yuan, Sheng-Fa; Chu, Fu-Lei

2006-05-01

Most artificial intelligence methods used in fault diagnosis are based on empirical risk minimisation principle and have poor generalisation when fault samples are few. Support vector machines (SVM) is a new general machine-learning tool based on structural risk minimisation principle that exhibits good generalisation even when fault samples are few. Fault diagnosis based on SVM is discussed. Since basic SVM is originally designed for two-class classification, while most of fault diagnosis problems are multi-class cases, a new multi-class classification of SVM named 'one to others' algorithm is presented to solve the multi-class recognition problems. It is a binary tree classifier composed of several two-class classifiers organised by fault priority, which is simple, and has little repeated training amount, and the rate of training and recognition is expedited. The effectiveness of the method is verified by the application to the fault diagnosis for turbo pump rotor.

Desire thinking as a confounder in the relationship between mindfulness and craving: Evidence from a cross-cultural validation of the Desire Thinking Questionnaire.

PubMed

Chakroun-Baggioni, Nadia; Corman, Maya; Spada, Marcantonio M; Caselli, Gabriele; Gierski, Fabien

2017-10-01

Desire thinking and mindfulness have been associated with craving. The aim of the present study was to validate the French version of the Desire Thinking Questionnaire (DTQ) and to investigate the relationship between mindfulness, desire thinking and craving among a sample of university students. Four hundred and ninety six university students completed the DTQ and measures of mindfulness, craving and alcohol use. Results from confirmatory factor analyses showed that the two-factor structure proposed in the original DTQ exhibited suitable goodness-of-fit statistics. The DTQ also demonstrated good internal reliability, temporal stability and predictive validity. A set of linear regressions revealed that desire thinking had a confounding effect in the relationship between mindfulness and craving. The confounding role of desire thinking in the relationship between mindfulness and craving suggests that interrupting desire thinking may be a viable clinical option aimed at reducing craving. Copyright © 2017 Elsevier B.V. All rights reserved.

Chitosan/waste coffee-grounds composite: An efficient and eco-friendly adsorbent for removal of pharmaceutical contaminants from water.

PubMed

Lessa, Emanuele F; Nunes, Matheus L; Fajardo, André R

2018-06-01

Waste coffee-grounds (WCG), a poorly explored source of biocompounds, were combined with chitosan (Cs) and poly(vinyl alcohol) (PVA) in order to obtain composites. Overall, WCG showed a good interaction with the polymeric matrix and good dispersibility up to 10 wt-%. At 5 wt-% WCG, the composite exhibited a noticeable enhancement (from 10 to 44%) of the adsorption of pharmaceuticals (metamizol (MET), acetylsalicylic acid (ASA), acetaminophen (ACE), and caffeine (CAF)) as compared to the pristine sample. The highest removal efficiency was registered at pH 6 and the removal followed the order ASA > CAF > ACE > MET. For all pharmaceuticals, the adsorption kinetics was found to follow the pseudo-second order model, while the adsorption mechanism was explained by the Freundlich isotherm. Reuse experiments indicated that the WCG-containing composite has an attractive cost-effectiveness since it presented a remarkable reusability in at least five consecutive adsorption/desorption cycles. Copyright © 2018 Elsevier Ltd. 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.

A dual-responsive colorimetric and fluorescent chemosensor based on diketopyrrolopyrrole derivative for naked-eye detection of Fe3+ and its practical application.

PubMed

Zhang, Shanshan; Sun, Tao; Xiao, Dejun; Yuan, Fang; Li, Tianduo; Wang, Enhua; Liu, Haixia; Niu, Qingfen

2018-01-15

A novel dual-responsive colorimetric and fluorescent chemosensor L based on diketopyrrolopyrrole derivative for Fe 3+ detection was designed and synthesized. In presence of Fe 3+ , sensor L displayed strong colorimetric response as amaranth to rose pink and significant fluorescence enhancement and chromogenic change, which served as a naked-eye indicator by an obvious color change from purple to red. The binding constant for L-Fe 3+ complex was found as 2.4×10 4 with the lower detection limit of 14.3nM. The sensing mechanism was investigated in detail by fluorescence measurements, IR and 1 H NMR spectra. Sensor L for Fe 3+ detection also exhibited high anti-interference performance, good reversibility, wide pH response range and instantaneous response time. Furthermore, the sensor L has been used to quantify Fe 3+ ions in practical water samples with good recovery. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of γ-hydroxybutyrate in human urine samples by ion exclusion and ion exchange two-dimensional chromatography system.

PubMed

Liu, Junwei; Deng, Zhifen; Zhu, Zuoyi; Wang, Yong; Wang, Guoqing; Sun, Yu-An; Zhu, Yan

2017-12-15

A two-dimensional ion chromatography system was developed for the determination of γ-hydroxybutyrate (GHB) in human urine samples. Ion exclusion chromatography was used in the first dimensional separation for elimination of urine matrices and detection of GHB above 10mgL -1 , ion exchange chromatography was used in the second dimensional separation via column-switching technique for detection of GHB above 0.08mgL -1 . Under the optimized chromatographic conditions, the ion exclusion and ion exchange chromatography separation system exhibited satisfactory repeatability (RSD<3.1%, n=6) and good linearity in the range of 50-1000mgL -1 and 0.5-100mgL -1 , respectively. By this method, concentrations of GHB in the selected human urine samples were detected in the range of 0-1.57mgL -1 . The urine sample containing 0.89mgL -1 GHB was selected to evaluate the accuracy; the spiked recoveries of GHB were 95.9-102.8%. The results showed that the two-dimensional ion chromatography system was convenient and practical for the determination of GHB in human urine samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis and Antioxidant Activity of Extracts from Broccoli (Brassica oleracea L.) Sprouts.

PubMed

Jang, Hae Won; Moon, Joon-Kwan; Shibamoto, Takayuki

2015-02-04

Samples prepared from fresh broccoli (Brassica oleracea L.) sprouts by water distillation or freeze-drying were examined for antioxidant activity using three assays. All samples exhibited dose-dependent antioxidant activity. The antioxidant activity ranged from 74.48 ± 0.46% (less volatile sample) to 93.2 ± 0.2% (dichloromethane extract sample) at the level of 500 μg/mL. Both dichloromethane extract samples from a water distillate of broccoli sprouts and freeze-dried broccoli sprouts showed potent antioxidant activity, which was comparable to that of BHT. Among the 43 compounds positively identified by gas chromatography-mass spectrometry, 5-methylthiopentylnitrile (31.64 μg/g) was found in the greatest concentration, followed by 4-methylthiobutylisothiocyanate (14.55 μg/g), 4-methylthiobutylnitrile (10.63 μg/g), 3-methylthiopropylisothiocyanate (3.00 μg/g), and 4-methylpentylisothiocyanate (2.48 μg/g). These isothiocyanates are known to possess antioxidant properties. Possible phenolic antioxidants found are 4-(1-methylpropyl)phenol (0.012 μg/g), 4-methylphenol (0.159 μg/g), and 2-methoxy-4-vinylphenol (0.009 μg/g). The present study demonstrates that broccoli sprouts are a good source of natural antioxidants.

A highly sensitive monoclonal antibody based biosensor for quantifying 3-5 ring polycyclic aromatic hydrocarbons (PAHs) in aqueous environmental samples.

PubMed

Li, Xin; Kaattari, Stephen L; Vogelbein, Mary A; Vadas, George G; Unger, Michael A

2016-03-01

Immunoassays based on monoclonal antibodies (mAbs) are highly sensitive for the detection of polycyclic aromatic hydrocarbons (PAHs) and can be employed to determine concentrations in near real-time. A sensitive generic mAb against PAHs, named as 2G8, was developed by a three-step screening procedure. It exhibited nearly uniformly high sensitivity against 3-ring to 5-ring unsubstituted PAHs and their common environmental methylated PAHs, with IC 50 values between 1.68-31 μg/L (ppb). 2G8 has been successfully applied on the KinExA Inline Biosensor system for quantifying 3-5 ring PAHs in aqueous environmental samples. PAHs were detected at a concentration as low as 0.2 μg/L. Furthermore, the analyses only required 10 min for each sample. To evaluate the accuracy of the 2G8-based biosensor, the total PAH concentrations in a series of environmental samples analyzed by biosensor and GC-MS were compared. In most cases, the results yielded a good correlation between methods. This indicates that generic antibody 2G8 based biosensor possesses significant promise for a low cost, rapid method for PAH determination in aqueous samples.

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 facile in-situ hydrothermal synthesis of SrTiO3/TiO2 microsphere composite

NASA Astrophysics Data System (ADS)

Wang, Hongxing; Zhao, Wei; Zhang, Yubo; Zhang, Shimeng; Wang, Zihao; Zhao, Dan

2016-06-01

TiO2 was successfully used as sacrificed template to synthesise SrTiO3/TiO2 microsphere composite via an in-situ hydrothermal process. The diameter of SrTiO3/TiO2 microsphere was about 700 nm with the same size of the template, and all of the microspheres were in good dispersity. The optimized reaction parameters for the phase and morphology of the as-synthesized samples were investigated. The results showed the SrTiO3/TiO2 microsphere can be synthesized at 170 °C when the concentration of sodium hydroxide was 0.1 M. Lower hydrothermal temperature hampered the formation of the SrTiO3/TiO2 composite, the higher alkali concentration, however, will destroy the morphology of products. The formation mechanism of SrTiO3/TiO2 microsphere composite was proposed and the photocatalytic properties of the samples were characterized using methylene blue solution as the pollutant under the UV light irradiation. The results indicated the proper OH- concentration will provide a channel for Sr2+ to react with Ti4+ located in the template and form the SrTiO3/TiO2 composite, and those with micro-scaled spherical morphology exhibited good photocatalytic activities.

Mo-doped SnO2 mesoporous hollow structured spheres as anode materials for high-performance lithium ion batteries

NASA Astrophysics Data System (ADS)

Wang, Xuekun; Li, Zhaoqiang; Zhang, Zhiwei; Li, Qun; Guo, Enyan; Wang, Chengxiang; Yin, Longwei

2015-02-01

We designed a facile infiltration route to synthesize mesoporous hollow structured Mo doped SnO2 using silica spheres as templates. It is observed that Mo is uniformly incorporated into SnO2 lattice in the form of Mo6+. The as-prepared mesoporous Mo-doped SnO2 LIBs anodes exhibit a significantly improved electrochemical performance with good cycling stability, high specific capacity and high rate capability. The mesoporous hollow Mo-doped SnO2 sample with 14 at% Mo doping content displays a specific capacity of 801 mA h g-1 after 60 cycles at a current density of 100 mA g-1, about 1.66 times higher than that of the pure SnO2 hollow sample. In addition, even if the current density is as high as 1600 mA g-1 after 60 cycles, it could still retain a stable specific capacity of 530 mA h g-1, exhibiting an extraordinary rate capability. The greatly improved electrochemical performance of the Mo-doped mesoporous hollow SnO2 sample could be attributed to the following factors. The large surface area and hollow structure can significantly enhance structural integrity by acting as mechanical buffer, effectively alleviating the volume changes generated during the lithiation/delithiation process. The incorporation of Mo into the lattice of SnO2 improves charge transfer kinetics and results in a faster Li+ diffusion rate during the charge-discharge process.

A rapid ultrasound-assisted dispersive liquid-liquid microextraction followed by ultra-performance liquid chromatography for the simultaneous determination of seven benzodiazepines in human plasma samples.

PubMed

Fernández, Purificación; González, Cristina; Pena, M Teresa; Carro, Antonia M; Lorenzo, Rosa A

2013-03-12

A simple and efficient ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) method has been developed for the determination of seven benzodiazepines (alprazolam, bromazepam, clonazepam, diazepam, lorazepam, lormetazepam and tetrazepam) in human plasma samples. Chloroform and methanol were used as extractant and disperser solvents, respectively. The influence of several variables (e.g., type and volume of dispersant and extraction solvents, pH, ultrasonic time and ionic strength) was carefully evaluated and optimized, using an asymmetric screening design 3(2)4(2)//16. Analysis of extracts was performed by ultra-performance liquid chromatography coupled with photodiode array detection (UPLC-PDA). Under the optimum conditions, two reversed-phases, Shield RP18 and C18 columns were successfully tested, obtaining good linearity in a range of 0.01-5μgmL(-1), with correlation coefficients r>0.996. Quantification limits ranged between 4.3-13.2ngmL(-1) and 4.0-14.8ngmL(-1), were obtained for C18 and Shield RP18 columns, respectively. The optimized method exhibited a good precision level, with relative standard deviation values lower than 8%. The recoveries studied at two spiked levels, ranged from 71 to 102% for all considered compounds. The proposed method was successfully applied to the analysis of seven benzodiazepines in real human plasma samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Measuring Psychological Capital: Construction and Validation of the Compound PsyCap Scale (CPC-12)

PubMed Central

Lorenz, Timo; Beer, Clemens; Pütz, Jan; Heinitz, Kathrin

2016-01-01

With the Psychological Capital Questionnaire (PCQ) being the standard measure to assess psychological capital (PsyCap) in the context of organizations, this paper aims to broaden this domain-specific approach by introducing a measure with universal claim. Two studies were conducted to create and validate a German self-report scale (CPC-12) measuring PsyCap. We performed confirmatory factor analyses and correlations with other positive psychological constructs on the data of two German samples (N1 = 321; N2 = 202). The twelve-item CPC-12 exhibits the anticipated factorial structure with a very good model fit and associations to other constructs concur with previous findings with other measures of PsyCap. PMID:27035437

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.

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids.

PubMed

Zheng, Xiaojiao; Qiu, Yunping; Zhong, Wei; Baxter, Sarah; Su, Mingming; Li, Qiong; Xie, Guoxiang; Ore, Brandon M; Qiao, Shanlei; Spencer, Melanie D; Zeisel, Steven H; Zhou, Zhanxiang; Zhao, Aihua; Jia, Wei

2013-08-01

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and inter-day (within 7 days) precision (< 10%), and good stability (< 20%) within 4 days at room temperature (23-25 °C), or 7 days when stored at -20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistics analysis of the concentrations of these target metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research.

Processing of Advanced Ceramics Which Have Potential for Use in Gas Turbine Aero Engines

DTIC Science & Technology

1989-02-01

reaons . Details on the availability of these publications may be obtained from: Graphics Section, National Research Council Canada, National...have been produced by hot isostatic pressing (HIP’ing) have good potential to be used as hot section components in gas turbine aero engines. This...Alumina, for example, maintains good corrosion resistance, good stiffness, and good strength at high temperatures, but exhibits very poor thermal shock

CO₂ adsorption on amine-functionalized periodic mesoporous benzenesilicas.

PubMed

Sim, Kyohyun; Lee, Nakwon; Kim, Joonseok; Cho, Eun-Bum; Gunathilake, Chamila; Jaroniec, Mietek

2015-04-01

CO2 adsorption was investigated on amine-functionalized mesoporous silica (SBA-15) and periodic mesoporous organosilica (PMO) samples. Hexagonally (p6mm) ordered mesoporous SBA-15 and benzene-PMO (BPMO) samples were prepared in the presence of Pluronic P123 block copolymer template under acidic conditions. Three kinds of amine-containing organosilanes and polyethylenimine were used to functionalize SBA-15 and BPMO. Small-angle X-ray scattering and nitrogen adsorption isotherms showed that these samples featured ordered mesostructure, high surface area, and narrow pore size distributions. Solid-state (13)C- and (29)Si cross-polarization magic-angle spinning NMR spectra showed chemical linkage between amine-containing modifiers and the surface of mesoporous materials. The chemically linked amine-containing modifiers were found to be on both the inner and outer surfaces. N-[3-(trimethoxysilyl)propyl]ethylenediamine-modified BPMO (A2-BPMO) sample exhibited the highest CO2 uptake (i.e., ∼3.03 mmol/g measured on a volumetric adsorption analyzer) and the fastest adsorption rate (i.e., ∼13 min to attain 90% of the maximum amount) among all the samples studied. Selectivity and reproducibility measurements for the A2-BPMO sample showed quite good performance in flowing N2 gas at 40 mL/min and CO2 gas of 60 mL/min at 25 °C.

Three hundred and eight nanometer excimer light therapy for alopecia universalis that is resistant to other treatments: A clinical study of 11 patients.

PubMed

Arakawa, Yukiyasu; Nomiyama, Tomoko; Katoh, Norito

2016-12-01

Three hundred and eight nanometer excimer light therapy has recently been reported to be effective against patchy alopecia areata (AA) in several clinical studies. However, these studies only included a few patients with severe forms of AA, and all of them exhibited poor outcomes. We further investigated the use of excimer light as a therapeutic option for cases of alopecia universalis (AU) that are resistant to other treatments. Eleven treatment-resistant AU patients were treated with a 308-nm excimer light at 2-week intervals for more than 16 sessions. Four patients achieved good responses and two patients exhibited poor responses. Three patients had Japanese skin type 1 and all of them achieved good responses. The radiation dose was increased until the patients exhibited marked erythema. The patients with Japanese skin type 3 who achieved good responses exhibited strong pigmentation at the irradiated sites. In conclusion, 308-nm excimer light therapy has significant effects on some AU patients who are resistant to other treatments and may be an alternative therapeutic option for AU. During the treatment of AU, high doses of radiation should be administrated until a strong inflammatory skin reaction is seen. © 2016 Japanese Dermatological Association.

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

Ding, Ling; Zhong, Jie-Cen; Qiu, Xing-Tai

Two series of lanthanide-carboxylates, [Ln(2,2′-dtba)(2,2′-Hdtba)(EtOH)]{sub n} (I:Ln=Eu(1a), Dy(1b)) and [Ln(2,2′-dtba)(2,2′-Hdtba)(4,4′-bpy){sub 0.5}]{sub n} (II:Ln=Eu(2a), Dy(2b), Tb(2c) 2,2′-H{sub 2}dtba=2,2′-dithiodibenzoic acid, 4,4′-bpy=4,4′-bipyridine) have been synthesized under hydrothermal conditions. Interestingly, the H{sub 2}dtba organic ligand was generated by in situ S–S reaction of 2-mercaptobenzoic acid. Compounds I and II possess different 2D layered structures based on similar 1D [Ln(2,2′-dtba)]{sup +} chains. Photoluminescence studies reveal that compounds I and II exhibit strong lanthanide characteristic emission bands. Remarkably, Compounds 1b and 2a both exhibit good photocatalytic activity for degradation of Rhodamine-B (Rh-B) under the simulated sunlight irradiation. - Graphical abstract: Two series of lanthanide-carboxylates have beenmore » in situ synthesized under hydrothermal conditions. The lanthanide-carboxylates exhibit strong lanthanide characteristic emission bands and good photocatalytic activity for degradation of Rhodamine-B. - Highlights: • 2D layered lanthanide-carboxylates with 2,2′-dithiodibenzoic acid. • In situ S–S reaction of 2-mercaptobenzoic acid under hydrothermal condition. • The Emission spectra of I and II exhibit the characteristic transition of lanthanide ions. • Compounds 1b and 2a exhibit good photocatalytic activity for degradation of Rhodamine-B.« less

Semiconducting and quartz microbalance (QCM) humidity sensor properties of TiO2 by sol gel calcination method

NASA Astrophysics Data System (ADS)

Yakuphanoglu, Fahrettin

2012-06-01

Titanium dioxide (TiO2) material was synthesized using the sol gel calcination method. The structural properties of the TiO2 semiconductor were investigated by atomic force microscopy. The electrical conductivity of the TiO2 was measured as a function of temperature and TiO2 exhibits a conductivity of 2.55 × 10-6 S/m at room temperature with activation energy of 104 meV. The electrical conductivity of the TiO2 at room temperature is higher than that of nanocrystalline TiO2 (3 × 10-7 S/m) and TiO2 thin film in air (5 × 10-9 S/m) and in vacuum (8.8 × 10-10 S/m). It was found that the electrical transport mechanism of the TiO2 is controlled by thermally activated mechanism. The optical band gap of the TiO2 powder sample was determined to be 3.17 eV, which is good in agreement with the bulk TiO2 (Eg = 3.2 eV). Up to our knowledge, there is no any reported data about the band gap of TiO2 nanopowder based on the diffused reflectance calculation. Quartz crystal microbalance (QCM) TiO2 humidity sensor was prepared. The sensor indicates a large frequency change with an interaction occurred between TiO2 and humidity molecules. The sensor exhibits a good repeatability when it was exposed to the moist air of 65% RH.

Point to point multispectral light projection applied to cultural heritage

NASA Astrophysics Data System (ADS)

Vázquez, D.; Alvarez, A.; Canabal, H.; Garcia, A.; Mayorga, S.; Muro, C.; Galan, T.

2017-09-01

Use of new of light sources based on LED technology should allow the develop of systems that combine conservation and exhibition requirements and allow to make these art goods available to the next generations according to sustainability principles. The goal of this work is to develop light systems and sources with an optimized spectral distribution for each specific point of the art piece. This optimization process implies to maximize the color fidelity reproduction and the same time to minimize the photochemical damage. Perceived color under these sources will be similar (metameric) to technical requirements given by the restoration team uncharged of the conservation and exhibition of the goods of art. Depending of the fragility of the exposed art objects (i.e. spectral responsivity of the material) the irradiance must be kept under a critical level. Therefore, it is necessary to develop a mathematical model that simulates with enough accuracy both the visual effect of the illumination and the photochemical impact of the radiation. Spectral reflectance of a reference painting The mathematical model is based on a merit function that optimized the individual intensity of the LED-light sources taking into account the damage function of the material and color space coordinates. Moreover the algorithm used weights for damage and color fidelity in order to adapt the model to a specific museal application. In this work we show a sample of this technology applied to a picture of Sorolla (1863-1923) an important Spanish painter title "woman walking at the beach".

Pain Behavior in Rheumatoid Arthritis Patients: Identification of Pain Behavior Subgroups

PubMed Central

Waters, Sandra J.; Riordan, Paul A.; Keefe, Francis J.; Lefebvre, John C.

2008-01-01

This study used Ward’s minimum variance hierarchical cluster analysis to identify homogeneous subgroups of rheumatoid arthritis patients suffering from chronic pain who exhibited similar pain behavior patterns during a videotaped behavior sample. Ninety-two rheumatoid arthritis patients were divided into two samples. Six motor pain behaviors were examined: guarding, bracing, active rubbing, rigidity, grimacing, and sighing. The cluster analysis procedure identified four similar subgroups in Sample 1 and Sample 2. The first subgroup exhibited low levels of all pain behaviors. The second subgroup exhibited a high level of guarding and low levels of other pain behaviors. The third subgroup exhibited high levels of guarding and rigidity and low levels of other pain behaviors. The fourth subgroup exhibited high levels of guarding and active rubbing and low levels of other pain behaviors. Sample 1 contained a fifth subgroup that exhibited a high level of active rubbing and low levels of other pain measures. The results of this study suggest that there are homogeneous subgroups within rheumatoid arthritis patient populations who differ in the motor pain behaviors they exhibit. PMID:18358682

Structural and spectral properties of undoped and tungsten doped Zn3(PO4)2ZnO nanopowders

NASA Astrophysics Data System (ADS)

Satyavathi, K.; Subba Rao, M.; Nagabhaskararao, Y.; Cole, Sandhya

2018-01-01

Pure and tungsten doped Zn3(PO4)2ZnO nanopowders (NPs) are prepared using sol-gel method. It has the longest track record of used in dentistry. It is used for cementation of inlays, crowns and orthodontic appliances. The systematic investigations like X-ray Diffraction (XRD), Scanning electron microscope (SEM) with energy dispersive X-ray (EDX) spectroscope, Transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, Optical absorption, Photoluminescence (PL) and Electron Paramagnetic Resonance (EPR) spectroscopic techniques are carried out for the prepared NPs. XRD pattern reveals that the prepared samples are in crystalline nature in which Zn3(PO4)2 corresponding to monoclinic phase and ZnO corresponding to hexagonal wurtzite phase, the average crystallite size of prepared nanopowders is in the range of 20-30 nm. The lattice strain, lattice cell parameters, unit cell volume and dislocation density of the prepared NPs are also calculated. The morphology of the prepared NPs is analyzed with SEM and TEM images. The distribution of Zn, P, O and W species in the prepared samples are identified by the chemical composition mapping through EDX. IR spectra of prepared samples exhibit the characteristic sharp absorption band peaks. The sharp absorption bands observed in the region 1200-900 cm-1 are due to complex stretching of characteristic PO43- groups. The absorption spectra exhibit a broad band around 696 nm is recognized due to 2B2g → 2B1g (dxy → dx2- y2) transition of tungsten ions. The PL spectra exhibit four emission peaks in the visible region indicating the quantum-confinement-induced photoluminescence. The CIE chromaticity diagram suggests that the prepared NPs have good color purity. The EPR spectra indicate that the W5+ ions occupy octahedral site symmetry in the host lattice.

Synthesis, characterization and photocatalysis enhancement of Eu2O3-ZnO mixed oxide nanoparticles

NASA Astrophysics Data System (ADS)

Mohamed, W. S.; Abu-Dief, Ahmed M.

2018-05-01

Pure ZnO nanoparticles (NPs) and mixed Eu2O3 and ZnO NPs with different Eu2O3 ratios (5%, 10%, and 15%) were synthesized by a precipitation method under optimum conditions. The synthesized samples were characterized by means of X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and UV-vis diffuse reflectance spectroscopy. The as-synthesized ZnO NPs exhibit high phase purity and a highly crystalline wurtzite ZnO structure. The mixed Eu2O3 and ZnO NPs exhibit a Eu2O3 zinc blend phase in addition to the wurtzite phase of pure ZnO, confirming the high purity and good crystallinity of the as-synthesized samples. The high-purity formation of ZnO and Eu2O3 phases was confirmed by FTIR and Raman spectra. Microstructural analysis by SEM and TEM confirmed the sphere-like morphology with different particle sizes (29-40 nm) of the as-synthesized samples. The photocatalytic activities of pure ZnO NPs and mixed Eu2O3 and ZnO NPs for the degradation of methylene blue were evaluated under ultraviolet (UV) irradiation. The results show that Eu2O3 plays an important role in the enhancement of the photocatalytic properties of ZnO NPs. We found that mixed 5% Eu2O3 and ZnO NPs exhibit the highest photocatalytic activity (degradation efficiency of 96.5% after 180 min of UV irradiation) as compared with pure ZnO NPs (degradation efficiency of 80.3% after 180 min of UV irradiation). The increased photocatalytic activity of the optimum mixed Eu2O3 and ZnO NPs is due to the high crystallinity, high surface area with small particle size, and narrow energy gap.

Validating the Center for Epidemiological Studies Depression Scale for Children in Rwanda

PubMed Central

Betancourt, Theresa; Scorza, Pamela; Meyers-Ohki, Sarah; Mushashi, Christina; Kayiteshonga, Yvonne; Binagwaho, Agnes; Stulac, Sara; Beardslee, William R.

2017-01-01

Objective We assessed the validity of the Center for Epidemiological Studies Depression Scale for Children (CES-DC) as a screen for depression in Rwandan children and adolescents. Although the CES-DC is widely used for depression screening in high-income countries, its validity in low-income and culturally diverse settings, including sub-Saharan Africa, is unknown. Method The CES-DC was selected based on alignment with local expressions of depression-like problems in Rwandan children and adolescents. To examine criterion validity, we compared CES-DC scores to depression diagnoses on a structured diagnostic interview, the Mini International Neuropsychiatric Interview for Children (MINI KID), in a sample of 367 Rwandan children and adolescents aged 10 through 17 years. Caregiver and child or adolescent self-reports endorsing the presence of local depression-like problems agahinda kenshi (persistent sorrow) and kwiheba (severe hopelessness) were also examined for agreement with MINI KID diagnosis. Results The CES-DC exhibited good internal reliability (α = .86) and test-retest reliability (r = .85). The area under the receiver operating characteristic curve for the CES-DC was 0.825 when compared to MINI KID diagnoses, indicating a strong ability to distinguish between depressed and nondepressed children and adolescents in Rwanda. A cut point of ≥ 30 corresponded with a sensitivity of 81.9% and a specificity of 71.9% in this referred sample. MINI KID diagnosis was well aligned with local expressions of depression-like problems. Conclusion The CES-DC demonstrates good psychometric properties for clinical screening and evaluation in Rwanda, and should be considered for use in this and other low-resource settings. Population samples are needed to determine a generalizable cut point in nonreferred samples. PMID:23200285

Development and Validation of a Measure of Maladaptive Social-Evaluative Beliefs Characteristic of Social Anxiety Disorder in Youth: The Report of Youth Social Cognitions (RYSC).

PubMed

Wong, Quincy J J; Certoma, Sarah P; McLellan, Lauren F; Halldorsson, Brynjar; Reyes, Natasha; Boulton, Kelsie; Hudson, Jennifer L; Rapee, Ronald M

2017-12-28

Recent research has started to examine the applicability of influential adult models of the maintenance of social anxiety disorder (SAD) to youth. This research is limited by the lack of psychometrically validated measures of underlying constructs that are developmentally appropriate for youth. One key construct in adult models of SAD is maladaptive social-evaluative beliefs. The current study aimed to develop and validate a measure of these beliefs in youth, known as the Report of Youth Social Cognitions (RYSC). The RYSC was developed with a clinical sample of youth with anxiety disorders (N = 180) and cross-validated in a community sample of youth (N = 305). In the clinical sample, the RYSC exhibited a 3-factor structure (negative evaluation, revealing self, and positive impression factors), good internal consistency, and construct validity. In the community sample, the 3-factor structure and the internal consistency of the RYSC were replicated, but the test of construct validity showed that the RYSC had similarly strong associations with social anxiety and depressed affect. The RYSC had good test-retest reliability overall, although the revealing self subscale showed lower temporal stability which improved when only older participants were considered (age ≥9 years). The RYSC in general was also shown to discriminate between youth with and without SAD although the revealing self subscale again performed suboptimally but improved when only older participants were considered. These findings provide psychometric support for the RYSC and justifies its use with youth in research and clinical settings requiring the assessment of maladaptive social-evaluative beliefs. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

In Situ Synthesis of a Magnetic Graphene Platform for the Extraction of Benzimidazoles from Food Samples and Analysis by High-Performance Liquid Chromatography

PubMed Central

Liu, Yulan; Wang, Xingyi; Li, Huimin; Chen, Junyu

2017-01-01

A novel method was proposed for the determination of five benzimidazoles (oxfendazole, mebendazole, flubendazole, albendazole, and fenbendazole) using magnetic graphene (G-Fe3O4). G-Fe3O4 was synthesized via in situ chemical coprecipitation. The properties of G-Fe3O4 were characterized by various instrumental methods. G-Fe3O4 exhibited a great adsorption ability and good stability towards analytes. Various experimental parameters that might affect the extraction efficiency such as the amount of G-Fe3O4, extraction solvent, extraction time, and desorption conditions were evaluated. Under the optimized conditions, a method based on G-Fe3O4 magnetic solid-phase extraction coupled with high-performance liquid chromatography was developed. A good linear response was observed in the concentration range of 0.100–100 μg/L for the five benzimidazoles, with correlation coefficients ranging from 0.9966 to 0.9998. The limits of detection (S/N = 3) of the method were between 17.2 and 32.3 ng/L. Trace benzimidazoles in chicken, chicken blood, and chicken liver samples were determined and the concentrations of oxfendazole, mebendazole, flubendazole, and fenbendazole in these samples were 13.0–20.2, 1.62–4.64, 1.94–6.42, and 0.292–1.04 ng/g, respectively. The recovery ranged from 83.0% to 115%, and the relative standard deviations were less than 7.9%. The proposed method was sensitive, reliable, and convenient for the analysis of trace benzimidazoles in food samples. PMID:28546882

Effects of common hemoglobin variants on HbA1c measurements in China: results for α- and β-globin variants measured by six methods.

PubMed

Xu, Anping; Chen, Weidong; Xia, Yong; Zhou, Yu; Ji, Ling

2018-04-07

HbA1c is a widely used biomarker for diabetes mellitus management. Here, we evaluated the accuracy of six methods for determining HbA1c values in Chinese patients with common α- and β-globin chains variants in China. Blood samples from normal subjects and individuals exhibiting hemoglobin variants were analyzed for HbA1c, using Sebia Capillarys 2 Flex Piercing (C2FP), Bio-Rad Variant II Turbo 2.0, Tosoh HLC-723 G8 (ver. 5.24), Arkray ADAMS A1c HA-8180V fast mode, Cobas c501 and Trinity Ultra2 systems. DNA sequencing revealed five common β-globin chain variants and three common α-globin chain variants. The most common variant was Hb E, followed by Hb New York, Hb J-Bangkok, Hb G-Coushatta, Hb Q-Thailand, Hb G-Honolulu, Hb Ube-2 and Hb G-Taipei. Variant II Turbo 2.0, Ultra2 and Cobas c501 showed good agreement with C2FP for most samples with variants. HLC-723 G8 yielded no HbA1c values for Hb J-Bangkok, Hb Q-Thailand and Hb G-Honolulu. Samples with Hb E, Hb G-Coushatta, Hb G-Taipei and Hb Ube-2 produced significant negative biases for HLC-723 G8. HA-8180V showed statistically significant differences for Hb E, Hb G-Coushatta, Hb G-Taipei, Hb Q-Thailand and Hb G-Honolulu. HA-8180V yielded no HbA1c values for Hb J-Bangkok. All methods showed good agreement for samples with Hb New York. Some common hemoglobin variants can interfere with HbA1c determination by the most popular methods in China.

Validation and comparison of the psychometric properties of the EQ-5D-3L and EQ-5D-5L instruments in Greece.

PubMed

Yfantopoulos, John N; Chantzaras, Athanasios E

2017-05-01

To validate and compare the psychometric properties of the EQ-5D-3L with the EQ-5D-5L classification systems in Greece. Participants (n = 2279) over 40 years old, sampled from the greater area of Athens using a multistage stratified quota sampling method, completed both EQ-5D versions, while information was also collected on socio-demographics and health-related characteristics. The EQ-5D-5L and EQ-5D-3L were evaluated in terms of agreement, ceiling effects, redistribution and inconsistency, informativity, and convergent and known-groups validity. The agreement between the EQ-5D-3L and EQ-5D-5L was high (ICC = 0.85). Ceiling effects decreased significantly in the EQ-5D-5L in all domains (P < 0.001), with "usual activities" (-21.4 %) and "self-care" (-20.1 %) showing the highest absolute and "anxiety/depression" the highest relative reduction (-32.46 %). Inconsistency was low (5.7 %). The increase in prevalence of problems was larger than the decrease in their severity, resulting in a lower mean health utility for the EQ-5D-5L. Overall absolute and relative informativity improved by 70.5 % and 16.4 %, respectively, in the EQ-5D-5L. Both instruments exhibited good convergent and known-groups validity, with evidence of a considerably better convergent performance and discriminatory ability of the EQ-5D-5L. Both EQ-5D versions demonstrated good construct validity and had consistent redistribution. The EQ-5D-5L system may be preferable to the EQ-5D-3L, as it exhibited superior performance in terms of lower ceiling effects, higher absolute and relative informativity, and improved convergent and known-groups validity efficiency.

Synthesis and luminescence studies of Eu (III) doped Sr2P2O7 phosphor for white LED applications

NASA Astrophysics Data System (ADS)

Khan, Z. S.; Ingale, N. B.; Omanwar, S. K.

2018-05-01

Europium (III) doped distrontium diphosphate (Sr2P2O7) is synthesized by slow vaporization method and its luminescence properties are carried out. Using X-Ray diffraction, the crystal structure of this material was confirmed. Photoluminescence (PL) measurement make clear the phosphor exhibited intense emission at 593 nm (yellow) and 612 nm (orange) respectively corresponding to 5D0→7F1 and 5D0→7F2 transitions of Eu3+ on excitation with most favourable 394 nm wavelengths. The remaining excitation peaks at 381 nm and 465 nm with broad band 200-310 nm are also witness in the excitation spectra. The particle morphology using SEM images shows micro level particles for this phosphor. The effect of concentration of Eu3+ ions on the PL intensity has also been investigated. It has been observed that the powder sample exhibits highest PL emission intensity for Eu3+ concentration of about 0.02 moles. The emission spectra exhibit orange performance (CIE chromaticity coordinates: X = 0.672, Y = 0.328), which is due to the 5D0→7F2 transitions of Eu3+ ions. This phosphor is very good for white LED applications.

The spectra and periodograms of anti-correlated discrete fractional Gaussian noise.

PubMed

Raymond, G M; Percival, D B; Bassingthwaighte, J B

2003-05-01

Discrete fractional Gaussian noise (dFGN) has been proposed as a model for interpreting a wide variety of physiological data. The form of actual spectra of dFGN for frequencies near zero varies as f(1-2H), where 0 < H < 1 is the Hurst coefficient; however, this form for the spectra need not be a good approximation at other frequencies. When H approaches zero, dFGN spectra exhibit the 1 - 2H power-law behavior only over a range of low frequencies that is vanishingly small. When dealing with a time series of finite length drawn from a dFGN process with unknown H, practitioners must deal with estimated spectra in lieu of actual spectra. The most basic spectral estimator is the periodogram. The expected value of the periodogram for dFGN with small H also exhibits non-power-law behavior. At the lowest Fourier frequencies associated with a time series of N values sampled from a dFGN process, the expected value of the periodogram for H approaching zero varies as f(0) rather than f(1-2H). For finite N and small H, the expected value of the periodogram can in fact exhibit a local power-law behavior with a spectral exponent of 1 - 2H at only two distinct frequencies.

Fabricated CeO2 nanopowders as a novel sensing platform for advanced forensic, electrochemical and photocatalytic applications

NASA Astrophysics Data System (ADS)

Rohini, B. S.; Nagabhushana, H.; Darshan, G. P.; Basavaraj, R. B.; Sharma, S. C.; Sudarmani, R.

2017-11-01

In Forensic investigation, identification of various types of ridge details are essential in order to fix the criminals associated in various crimes. Even though several methods and labeling agents are available to visualize latent finger prints (LFPs) there is still simple, accurate, cost-effective, and non-destructive tool is required. In the present work, CeO2 nanopowders (NPs) are prepared via simple solution combustion route using Tamarindus indica fruit extract as a fuel. The optimized NPs are utilized for visualization of LFPs on various surfaces by powder dusting method. Results revealed that visualized LFPs exhibit Level 3 features such as pores and ridge contours under normal light with high sensitivity and without background hindrance. The photometric characteristics of the prepared samples exhibit blue color emission and highly useful in warm light emitting diodes. The photocatalytic studies were carried out with different Methylene blue (MB) dye concentration and pH values. The obtained results reveal that the CeO2 NPs exhibits an excellent catalytic properties which can act as a good catalytic reagent. The findings demonstrate that the prepared NPs are quite useful as a labeling agent for visualization of LFPs, efficient catalysts for dye degradation as well as solid-state lighting applications.

Preparation of l-phenylalanine-imprinted solid-phase extraction sorbent by Pickering emulsion polymerization and the selective enrichment of l-phenylalanine from human urine.

PubMed

Li, Ji; Hu, Xiaoling; Guan, Ping; Zhang, Xiaoyan; Qian, Liwei; Zhang, Nan; Du, Chunbao; Song, Renyuan

2016-05-01

A novel l-phenylalanine molecularly imprinted solid-phase extraction sorbent was synthesized by the combination of Pickering emulsion polymerization and ion-pair dummy template imprinting. Compared to other polymerization methods, the molecularly imprinted polymers thus prepared exhibit a high specific surface, large pore diameter, and appropriate particle size. The key parameters for solid-phase extraction were optimized, and the result indicated that the molecularly imprinted polymer thus prepared exhibits a good recovery of 98.9% for l-phenylalanine. Under the optimized conditions of the procedure, an analytical method for l-phenylalanine was well established. By comparing the performance of the molecularly imprinted polymer and a commercial reverse-phase silica gel, the obtained molecularly imprinted polymer as an solid-phase extraction sorbent is more suitable, exhibiting high precision (relative standard deviation 3.2%, n = 4) and a low limit of detection (60.0 ± 1.9 nmol·L(-1) ) for the isolation of l-phenylalanine. Based on these results, the combination of the Pickering emulsion polymerization and ion-pair dummy template imprinting is effective for preparing selective solid-phase extraction sorbents for the separation of amino acids and organic acids from complex biological samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of annealing on the structural and optical properties of TiO{sub 2} powder prepared by sol-gel route

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

Halder, Nilanjan; Misra, Kamakhya Prakash

2016-05-06

Using titanium isopropoxide as the precursor, Titanium dioxide (TiO{sub 2}) powder was synthesized via sol-gel method, a promising low temperature route for preparing nanosized metal oxide semiconductors with good homogeneity at low cost. The as-prepared nano powder was thermally treated in air at 550, 650, 750, 900 and 1100°C for 1hr after drying at room temperature and used for further characterization. X-ray diffraction measurements showed that the annealing treatment has a strong impact on the crystal phase of TiO{sub 2} samples. The crystallite size as calculated from Debye Scherer formula lies in the range 29-69 nm and is found to increasemore » with increase in annealing temperature. Photoluminescence studies exhibit an improvement in the optical efficiency of the samples with post synthesis heat treatment. Annealing at temperature above 900°C results in a degradation of the structural and optical quality of the TiO{sub 2} nano powder samples.« less

Paleobiological Implications of the Isotopic Signatures ( 13C, 15N) of Fossil Mammal Collagen in Scladina Cave (Sclayn, Belgium)

NASA Astrophysics Data System (ADS)

Bocherens, Hervé; Billiou, Daniel; Patou-Mathis, Marylène; Bonjean, Dominique; Otte, Marcel; Mariotti, André

1997-11-01

An isotopic investigation of upper Pleistocene mammal bones and teeth from Scladina cave (Sclayn, Belgium) demonstrated the very good quality of collagen preservation. A preliminary screening of the samples used the amount of nitrogen in whole bone and dentine in order to estimate the preserved amount of collagen before starting the extraction process. The isotopic abundances of fossil specimens from still-extant species are consistent with their trophic position. Moreover, the 15N isotopic abundance is higher in dentine than in bone in bears and hyenas, a phenomenon already observed in modern specimens. These results demonstrate that the isotopic compositions of samples from Scladina cave can be interpreted in ecological terms. Mammoths exhibit a high 15N isotopic abundance relative to other herbivores, as was the case in Siberian and Alaskan samples. These results suggest distinctive dietary adaptations in herbivores living in the mammoth steppe. Cave bears are clearly isotopically different from coeval brown bears, suggesting an ecological separation between species, with a pure vegetarian diet for cave bear and an omnivorous diet for brown bear.

Human unrestricted somatic stem cells loaded in nanofibrous PCL scaffold and their healing effect on skin defects.

PubMed

Bahrami, Hoda; Keshel, Saeed Heidari; Chari, Aliakbar Jafari; Biazar, Esmaeil

2016-09-01

Unrestricted somatic stem cells (USSCs) loaded in nanofibrous polycaprolactone (PCL) scaffolds can be used for skin regeneration when grafted onto full-thickness skin defects of rats. Nanofibrous PCL scaffolds were designed by the electrospinning method and crosslinked with laminin protein. Afterwards, the scaffolds were evaluated by scanning electron microscopy, and physical and mechanical assays. In this study, nanofibrous PCL scaffolds loaded with USSCs were grafted onto the skin defects. The wounds were subsequently investigated 21 days after grafting. Results of mechanical and physical analyses showed good resilience and compliance to movement as a skin graft. In animal models; study samples exhibited the most pronounced effect on wound closure, with statistically significant improvement in wound healing being seen at 21 days post-operatively. Histological examinations of healed wounds from all samples showed a thin epidermis plus recovered skin appendages in the dermal layer for samples with cell. Thus, the graft of nanofibrous PCL scaffolds loaded with USSC showed better results during the healing process of skin defects in rat models.

Influence of heat treatment on bond strength and corrosion resistance of sol-gel derived bioglass-ceramic coatings on magnesium alloy.

PubMed

Shen, Sibo; Cai, Shu; Xu, Guohua; Zhao, Huan; Niu, Shuxin; Zhang, Ruiyue

2015-05-01

In this study, bioglass-ceramic coatings were prepared on magnesium alloy substrates through sol-gel dip-coating route followed by heat treatment at the temperature range of 350-500°C. Structure evolution, bond strength and corrosion resistance of samples were studied. It was shown that increasing heat treatment temperature resulted in denser coating structure as well as increased interfacial residual stress. A failure mode transition from cohesive to adhesive combined with a maximum on the measured bond strength together suggested that heat treatment enhanced the cohesion strength of coating on the one hand, while deteriorated the adhesion strength of coating/substrate on the other, thus leading to the highest bond strength of 27.0MPa for the sample heat-treated at 450°C. This sample also exhibited the best corrosion resistance. Electrochemical tests revealed that relative dense coating matrix and good interfacial adhesion can effectively retard the penetration of simulated body fluid through the coating, thus providing excellent protection for the underlying magnesium alloy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fast preconcentration of trace rare earth elements from environmental samples by di(2-ethylhexyl)phosphoric acid grafted magnetic nanoparticles followed by inductively coupled plasma mass spectrometry detection

NASA Astrophysics Data System (ADS)

Yan, Ping; He, Man; Chen, Beibei; Hu, Bin

2017-10-01

In this work, di(2-ethylhexyl)phosphoric acid (P204) grafted magnetic nanoparticles were synthesized by fabricating P204 onto Fe3O4@TiO2 nanoparticles based on Lewis acid-base interaction between Ti and phosphate group under weakly acidic condition. The prepared Fe3O4@TiO2@P204 nanoparticles exhibited excellent selectivity for rare earth elements, and good anti-interference ability. Based on it, a method of magnetic solid phase extraction (MSPE) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for fast preconcentration and determination of trace rare earth elements in environmental samples. Under the optimal conditions, the detection limits of rare earth elements were in the range of 0.01 (Tm)-0.12 (Nd) ng L- 1 with an enrichment factor of 100-fold, and the relative standard deviations ranged from 4.9 (Pr) to 10.7% (Er). The proposed method was successfully applied to the determination of rare earth elements in environmental samples, including river water, lake water, seawater and sediment.

Molecularly imprinted polymer online solid-phase extraction coupled with high-performance liquid chromatography-UV for the determination of three sulfonamides in pork and chicken.

PubMed

He, Jinxing; Wang, Shuo; Fang, Guozhen; Zhu, Huaping; Zhang, Yan

2008-05-14

A selective imprinted amino-functionalized silica gel sorbent was prepared by combining a surface molecular imprinting technique with a sol-gel process for online solid-phase extraction-HPLC determination of three trace sulfonamides in pork and chicken muscle. The imprinted functionalized silica gel sorbent exhibited selectivity and fast kinetics for the adsorption and desorption of sulfonamides. With a sample loading flow rate of 4 mL min (-1) for 12.5 min, enhancement factors and detection limits for three sulfonamides ( S/ N = 3) were achieved. The precision (RSD) for nine replicate online sorbent extractions of 5 microg L (-1) sulfonamides was less than 4.5%. The sorbent also offered good linearity ( r (2) > 0.99) for online solid-phase extraction of trace levels of sulfonamides. The method was applied to the determination of sulfonamides in pork and chicken muscle samples. The prepared polymer sorbent shows promise for online solid-phase extraction for HPLC determination of trace levels of sulfonamides in pork and chicken samples.

Nanoscale Multigate TiN Metal Nanocrystal Memory Using High-k Blocking Dielectric and High-Work-Function Gate Electrode Integrated on Silcon-on-Insulator Substrate

NASA Astrophysics Data System (ADS)

Lu, Chi-Pei; Luo, Cheng-Kei; Tsui, Bing-Yue; Lin, Cha-Hsin; Tzeng, Pei-Jer; Wang, Ching-Chiun; Tsai, Ming-Jinn

2009-04-01

In this study, a charge-trapping-layer-engineered nanoscale n-channel trigate TiN nanocrystal nonvolatile memory was successfully fabricated on silicon-on-insulator (SOI) wafer. An Al2O3 high-k blocking dielectric layer and a P+ polycrystalline silicon gate electrode were used to obtain low operation voltage and suppress the back-side injection effect, respectively. TiN nanocrystals were formed by annealing TiN/Al2O3 nanolaminates deposited by an atomic layer deposition system. The memory characteristics of various samples with different TiN wetting layer thicknesses, post-deposition annealing times, and blocking oxide thicknesses were also investigated. The sample with a thicker wetting layer exhibited a much larger memory window than other samples owing to its larger nanocrystal size. Good retention with a mere 12% charge loss for up to 10 years and high endurance were also obtained. Furthermore, gate disturbance and read disturbance were measured with very small charge migrations after a 103 s stressing bias.

Magnetic covalent triazine framework for rapid extraction of phthalate esters in plastic packaging materials followed by gas chromatography-flame ionization detection.

PubMed

Yan, Zijun; He, Man; Chen, Beibei; Gui, Bo; Wang, Cheng; Hu, Bin

2017-11-24

Covalent triazine frameworks (CTFs), featuring with high surface area, good thermal, chemical and mechanical stability, are good adsorbents in sample pretreatment. Herein, magnetic CTFs/Ni composite was prepared by in situ reduction of nickel ions on CTFs matrix with a solvothermal method. The prepared CTFs/Ni composite exhibited good preparation reproducibility, high chemical stability, and high extraction efficiency for targeted phthalate esters (PAEs) due to π-π interaction and hydrophobic effect. The porous structure of CTFs/Ni composite benefited the fast transfer of target PAEs from aqueous solution to the adsorbents, and the integrated magnetism contributed to the rapid separation of adsorbents from sample and elution solution. Based on it, a novel method of magnetic solid phase extraction (MSPE) combined with gas chromatography-flame ionization detector (GC-FID) was developed for the analysis of PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-2-ethylhexl phthalate (DEHP), and di-n-octyl phthalate (DNOP) in plastic packaging materials. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) for six PAEs were found to be in the range of 0.024-0.085mg/kg. The linear range was 0.32-16mg/kg for DMP, DEP, 0.08-80mg/kg for DBP, 0.16-32mg/kg for BBP, DEHP, and 0.32-32mg/kg for DNOP, respectively. The enrichment factors ranged from 59 to 88-fold (theoretical enrichment factor was 133-fold). The proposed method was successfully applied to the analysis of PAEs in various plastic packaging materials with recoveries in the range of 70.6-119% for the spiked samples. This method is characterized with short operation time, high sensitivity, low consumption of harmful organic solvents and can be extended to the analysis of other trace aromatic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

The Value of Educators "On the Floor": Comparing Three Modes of Presenting Science on a Sphere®

ERIC Educational Resources Information Center

Hayward, Jeff; Hart, Jolene K.

2015-01-01

Exhibit experiences at most museums are designed to be self-guided rather than facilitated; and it's certainly a good goal to make exhibit interpretation clear enough to be understood on one's own. The primary rationale for not staffing exhibits is the ongoing personnel cost, but that should be weighed against the value of "on the floor"…

Fast detection of atrazine in corn using thermometric biosensors.

PubMed

Qie, Zhiwei; Ning, Baoan; Liu, Ming; Bai, Jialei; Peng, Yuan; Song, Nan; Lv, Zhiqiang; Wang, Ying; Sun, Siming; Su, Xuan; Zhang, Yihong; Gao, Zhixian

2013-09-07

Fast detection is important in screening large-scale samples. This study establishes a direct competitive ELISA method (dcTELISA) based on an enzyme thermistor for fast atrazine (ATZ) detection. ATZ competes with β-lactamase-labeled ATZ (ATZ-E) for the binding sites on anti-ATZ monoclonal antibody (mAb). The mAb are covalently bound to Controlled Pore Glass (CPG) in an immunoreactor to form immunocomplexes with ATZ and ATZ-E. Several parameters of biosensor performance were optimized, such as the ATZ-E concentration, concentration and nature of the substrate, flow rate, and effect of temperature on the sensor response. After optimization, the assay time for a single sample was 12 min. The work process and result were compared with those of high-performance liquid chromatography (HPLC). The detection results exhibited a recovery rate of 88% to 107% in ATZ-spiked fresh cut corn stalks and silage samples. The results obtained via dcTELISA had good correlation with that of HPLC, and the biosensor response was reproducible and stable even when used continuously for over 4 months. All these properties suggested that the fast detection method, dcTELISA, may be used to detect pesticide residue in large-scale samples.

An evaluation of Brix refractometry instruments for measurement of colostrum quality in dairy cattle.

PubMed

Bielmann, V; Gillan, J; Perkins, N R; Skidmore, A L; Godden, S; Leslie, K E

2010-08-01

Acquisition of high quality colostrum is an important factor influencing neonatal calf health. Many methods have been used to assess the Ig concentration of colostrum; however, improved, validated evaluation tools are needed. The aims of this study were to evaluate both optical and digital Brix refractometer instruments for the measurement of Ig concentration of colostrum as compared with the gold standard radial immunodiffusion assay laboratory assessment and to determine the correlation between Ig measurements taken from fresh and frozen colostrum samples for both Brix refractometer instruments. This research was completed using 288 colostrum samples from 3 different farms. It was concluded that the optical and digital Brix refractometers were highly correlated for both fresh and frozen samples (r=0.98 and r=0.97, respectively). Correlation between both refractometer instruments for fresh and frozen samples and the gold standard radial immunodiffusion assay were determined to be very similar, with a correlation coefficient between 0.71 and 0.74. Both instruments exhibited excellent test characteristics, indicating an appropriate cut-off point of 22% Brix score for the identification of good quality colostrum. Copyright (c) 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Microstructure and Wear Resistance of Composite Coating by Laser Cladding Al/TiN on the Ti-6Al-4V Substrate

NASA Astrophysics Data System (ADS)

Zhang, H. X.; Yu, H. J.; Chen, C. Z.

2015-05-01

The composite coatings were fabricated by laser cladding Al/TiN pre-placed powders on Ti-6Al-4V substrate for enhancing wear resistance and hardness of the substrate. The composite coatings were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The sliding wear tests were performed by MM200 wear test machine. The hardness of the coatings was tested by HV-1000 hardness tester. After laser cladding, it was found that there was a good metallurgical bond between the coating and the substrate. The composite coatings were mainly composed of the matrix of β-Ti (Al) and the reinforcements of titanium nitride (TiN), Ti3Al, TiAl and Al3Ti. The hardness and wear resistance of the coatings on four samples were greatly improved, among which sample 4 exhibited the highest hardness and best wear resistance. The hardness of the coating on sample 4 was approximately 2.5 times of the Ti-6Al-4V substrate. And the wear resistance of sample 4 was four times of the substrate.

Determination of halonitromethanes and haloacetamides: an evaluation of sample preservation and analyte stability in drinking water.

PubMed

Liew, Deborah; Linge, Kathryn L; Joll, Cynthia A; Heitz, Anna; Charrois, Jeffrey W A

2012-06-08

Simultaneous quantitation of 6 halonitromethanes (HNMs) and 5 haloacetamides (HAAms) was achieved with a simplified liquid-liquid extraction (LLE) method, followed by gas chromatography-mass spectrometry. Stability tests showed that brominated tri-HNMs immediately degraded in the presence of ascorbic acid, sodium sulphite and sodium borohydride, and also reduced in samples treated with ammonium chloride, or with no preservation. Both ammonium chloride and ascorbic acid were suitable for the preservation of HAAms. Ammonium chloride was most suitable for preserving both HNMs and HAAms, although it is recommended that samples be analysed as soon as possible after collection. While groundwater samples exhibited a greater analytical bias compared to other waters, the good recoveries (>90%) of most analytes in tap water suggest that the method is very appropriate for determining these analytes in treated drinking waters. Application of the method to water from three drinking water treatment plants in Western Australia indicating N-DBP formation did occur, with increased detections after chlorination. The method is recommended for low-cost, rapid screening of both HNMs and HAAms in drinking water. Copyright © 2012 Elsevier B.V. All rights reserved.

Preparation and Characterization of Biomass-Derived Advanced Carbon Materials for Lithium-Ion Battery Applications

NASA Astrophysics Data System (ADS)

Hardiansyah, Andri; Chaldun, Elsy Rahimi; Nuryadin, Bebeh Wahid; Fikriyyah, Anti Khoerul; Subhan, Achmad; Ghozali, Muhammad; Purwasasmita, Bambang Sunendar

2018-04-01

In this study, carbon-based advanced materials for lithium-ion battery applications were prepared by using soybean waste-based biomass material, through a straightforward process of heat treatment followed by chemical modification processes. Various types of carbon-based advanced materials were developed. Physicochemical characteristics and electrochemical performance of the resultant materials were characterized systematically. Scanning electron microscopy observation revealed that the activated carbon and graphene exhibits wrinkles structures and porous morphology. Electrochemical impedance spectroscopy (EIS) revealed that both activated carbon and graphene-based material exhibited a good conductivity. For instance, the graphene-based material exhibited equivalent series resistance value of 25.9 Ω as measured by EIS. The graphene-based material also exhibited good reversibility and cyclic performance. Eventually, it would be anticipated that the utilization of soybean waste-based biomass material, which is conforming to the principles of green materials, could revolutionize the development of advanced material for high-performance energy storage applications, especially for lithium-ion batteries application.

Preparation and Characterization of Biomass-Derived Advanced Carbon Materials for Lithium-Ion Battery Applications

NASA Astrophysics Data System (ADS)

Hardiansyah, Andri; Chaldun, Elsy Rahimi; Nuryadin, Bebeh Wahid; Fikriyyah, Anti Khoerul; Subhan, Achmad; Ghozali, Muhammad; Purwasasmita, Bambang Sunendar

2018-07-01

In this study, carbon-based advanced materials for lithium-ion battery applications were prepared by using soybean waste-based biomass material, through a straightforward process of heat treatment followed by chemical modification processes. Various types of carbon-based advanced materials were developed. Physicochemical characteristics and electrochemical performance of the resultant materials were characterized systematically. Scanning electron microscopy observation revealed that the activated carbon and graphene exhibits wrinkles structures and porous morphology. Electrochemical impedance spectroscopy (EIS) revealed that both activated carbon and graphene-based material exhibited a good conductivity. For instance, the graphene-based material exhibited equivalent series resistance value of 25.9 Ω as measured by EIS. The graphene-based material also exhibited good reversibility and cyclic performance. Eventually, it would be anticipated that the utilization of soybean waste-based biomass material, which is conforming to the principles of green materials, could revolutionize the development of advanced material for high-performance energy storage applications, especially for lithium-ion batteries application.

Magnetic solid phase extraction of typical polycyclic aromatic hydrocarbons from environmental water samples with metal organic framework MIL-101 (Cr) modified zero valent iron nano-particles.

PubMed

Zhou, Qingxiang; Lei, Man; Wu, Yalin; Yuan, Yongyong

2017-03-03

Metal-organic framework material has been paid more attention because of its good physical and chemical properties. Nanoscale zero valent iron is also in the center of concern recently. Combination of their merits will give impressive results. Present study firstly synthesized a new magnetic nanomaterial nano-scale zero valent iron-functionalized metal-organic framworks MIL-101 (Fe@MIL-101) by co-precipitation method. The morphology and structure of the as-prepared Fe@MIL-101 were characterized by transmission electron microscopy and X-ray diffraction, etc. The experimental results showed that Fe@MIL-101 earned good adsorption ability to polycyclic aromatic hydrocarbons. The limits of detection of developed magnetic solid phase extraction were all below 0.064μgL -1 and precision can be expressed as relative standard deviation (RSD, %) and which was better than 4.4% (n=6). The real water analysis indicated that the spiked recoveries were satisfied, and Fe@MIL-101 earned excellent reusability. All these demonstrated that Fe@MIL-101 exhibited excellent adsorption capability to polycyclic aromatic hydrocarbons and would be a good adsorbent for development of new monitoring methods for environmental pollutants. Copyright © 2017 Elsevier B.V. All rights reserved.

Antibacterial Effects and Biocompatibility of Titania Nanotubes with Octenidine Dihydrochloride/Poly(lactic-co-glycolic acid).

PubMed

Xu, Zhiqiang; Lai, Yingzhen; Wu, Dong; Huang, Wenxiu; Huang, Sijia; Zhou, Lin; Chen, Jiang

2015-01-01

Titanium (Ti) implants with long-term antibacterial ability and good biocompatibility are highly desirable materials that can be used to prevent implant-associated infections. In this study, titania nanotubes (TNTs) were synthesized on Ti surfaces through electrochemical anodization. Octenidine dihydrochloride (OCT)/poly(lactic-co-glycolic acid) (PLGA) was infiltrated into TNTs using a simple solvent-casting technique. OCT/PLGA-TNTs demonstrated sustained drug release and maintained the characteristic hollow structures of TNTs. TNTs (200 nm in diameter) alone exhibited slight antibacterial effect and good osteogenic activity but also evidently impaired adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs). OCT/PLGA-TNTs (100 nm in diameter) supported BMSC adhesion and proliferation and showed good osteogenesis-inducing ability. OCT/PLGA-TNTs also exhibited good long-term antibacterial ability within the observation period of 7 d. The synthesized drug carrier with relatively long-term antibacterial ability and enhanced excellent biocompatibility demonstrated significant potential in bone implant applications.

Antibacterial Effects and Biocompatibility of Titania Nanotubes with Octenidine Dihydrochloride/Poly(lactic-co-glycolic acid)

PubMed Central

Xu, Zhiqiang; Lai, Yingzhen; Wu, Dong; Huang, Wenxiu; Huang, Sijia; Zhou, Lin; Chen, Jiang

2015-01-01

Titanium (Ti) implants with long-term antibacterial ability and good biocompatibility are highly desirable materials that can be used to prevent implant-associated infections. In this study, titania nanotubes (TNTs) were synthesized on Ti surfaces through electrochemical anodization. Octenidine dihydrochloride (OCT)/poly(lactic-co-glycolic acid) (PLGA) was infiltrated into TNTs using a simple solvent-casting technique. OCT/PLGA-TNTs demonstrated sustained drug release and maintained the characteristic hollow structures of TNTs. TNTs (200 nm in diameter) alone exhibited slight antibacterial effect and good osteogenic activity but also evidently impaired adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs). OCT/PLGA-TNTs (100 nm in diameter) supported BMSC adhesion and proliferation and showed good osteogenesis-inducing ability. OCT/PLGA-TNTs also exhibited good long-term antibacterial ability within the observation period of 7 d. The synthesized drug carrier with relatively long-term antibacterial ability and enhanced excellent biocompatibility demonstrated significant potential in bone implant applications. PMID:26090449

A study of personal and area airborne asbestos concentrations during asbestos abatement: a statistical evaluation of fibre concentration data.

PubMed

Lange, J H; Lange, P R; Reinhard, T K; Thomulka, K W

1996-08-01

Data were collected and analysed on airborne concentrations of asbestos generated by abatement of different asbestos-containing materials using various removal practices. Airborne concentrations of asbestos are dramatically variable among the types of asbestos-containing material being abated. Abatement practices evaluated in this study were removal of boiler/pipe insulation in a crawl space, ceiling tile, transite, floor tile/mastic with traditional methods, and mastic removal with a high-efficiency particulate air filter blast track (shot-blast) machine. In general, abatement of boiler and pipe insulation produces the highest airborne fibre levels, while abatement of floor tile and mastic was observed to be the lowest. A comparison of matched personal and area samples was not significantly different, and exhibited a good correlation using regression analysis. After adjusting data for outliers, personal sample fibre concentrations were greater than area sample fibre concentrations. Statistical analysis and sample distribution of airborne asbestos concentrations appear to be best represented in a logarithmic form. Area sample fibre concentrations were shown in this study to have a larger variability than personal measurements. Evaluation of outliers in fibre concentration data and the ability of these values to skew sample populations is presented. The use of personal and area samples in determining exposure, selecting personal protective equipment and its historical relevance as related to future abatement projects is discussed.

Development of a multiplexed urine assay for prostate cancer diagnosis.

PubMed

Vener, Tatiana; Derecho, Carlo; Baden, Jonathan; Wang, Haiying; Rajpurohit, Yashoda; Skelton, Joanne; Mehrotra, Jyoti; Varde, Shobha; Chowdary, Dondapati; Stallings, Walt; Leibovich, Bradley; Robin, Howard; Pelzer, Alexandre; Schäfer, Georg; Auprich, Marco; Mannweiler, Sebastian; Amersdorfer, Peter; Mazumder, Abhijit

2008-05-01

Several studies have demonstrated the value of DNA methylation in urine-based assays for prostate cancer diagnosis. However, a multicenter validation with a clinical prototype has not been published. We developed a multiplexed, quantitative methylation-specific polymerase chain reaction (MSP) assay consisting of 3 methylation markers, GSTP1, RARB, and APC, and an endogenous control, ACTB, in a closed-tube, homogeneous assay format. We tested this format with urine samples collected after digital rectal examination from 234 patients with prostate-specific antigen (PSA) concentrations > or =2.5 microg/L in 2 independent patient cohorts from 9 clinical sites. In the first cohort of 121 patients, we demonstrated 55% sensitivity and 80% specificity, with area under the curve (AUC) 0.69. In the second independent cohort of 113 patients, we found a comparable sensitivity of 53% and specificity of 76% (AUC 0.65). In the first cohort, as well as in a combined cohort, the MSP assay in conjunction with total PSA, digital rectal examination status, and age improved the AUC without MSP, although the difference was not statistically significant. Importantly, the GSTP1 cycle threshold value demonstrated a good correlation (R = 0.84) with the number of cores found to contain prostate cancer or premalignant lesions on biopsy. Moreover, samples that exhibited methylation for either GSTP1 or RARB typically contained higher tumor volumes at prostatectomy than those samples that did not exhibit methylation. These data confirm and extend previously reported studies and demonstrate the performance of a clinical prototype assay that should aid urologists in identifying men who should undergo biopsy.

Highly sensitive analysis of polycyclic aromatic hydrocarbons in environmental water with porous cellulose/zeolitic imidazolate framework-8 composite microspheres as a novel adsorbent coupled with high-performance liquid chromatography.

PubMed

Liang, Xiaotong; Liu, Shengquan; Zhu, Rong; Xiao, Lixia; Yao, Shouzhuo

2016-07-01

In this work, novel cellulose/zeolitic imidazolate frameworks-8 composite microspheres have been successfully fabricated and utilized as sorbent for environmental polycyclic aromatic hydrocarbons efficient extraction and sensitive analysis. The composite microspheres were synthesized through the in situ hydrothermal growth of zeolitic imidazolate frameworks-8 on cellulose matrix, and exhibited favorable hierarchical structure with chemical composition as assumed through scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction patterns, and Brunauer-Emmett-Teller surface areas characterization. A robust and highly efficient method was then successfully developed with as-prepared composite microspheres as novel solid-phase extraction sorbent with optimum extraction conditions, such as sorbent amount, sample volume, extraction time, desorption conditions, volume of organic modifier, and ionic strength. The method exhibited high sensitivity with low limit of detection down to 0.1-1.0 ng/L and satisfactory linearity with correlation coefficients ranging from 0.9988 to 0.9999, as well as good recoveries of 66.7-121.2% with relative standard deviations less than 10% for environmental polycyclic aromatic hydrocarbons analysis. Thus, our method was convenient and efficient for polycyclic aromatic hydrocarbons extraction and detection, potential for future environmental water samples analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Visible light photocatalytic H2-production activity of wide band gap ZnS nanoparticles based on the photosensitization of graphene

NASA Astrophysics Data System (ADS)

Wang, Faze; Zheng, Maojun; Zhu, Changqing; Zhang, Bin; Chen, Wen; Ma, Li; Shen, Wenzhong

2015-08-01

Visible light photocatalytic H2 production from water splitting is considered an attractive way to solve the increasing global energy crisis in modern life. In this study, a series of zinc sulfide nanoparticles and graphene (GR) sheet composites were synthesized by a two-step hydrothermal method, which used zinc chloride, sodium sulfide, and graphite oxide (GO) as the starting materials. The as-prepared ZnS-GR showed highly efficient visible light photocatalytic activity in hydrogen generation. The morphology and structure of the composites obtained by transmission electron microscope and x-ray diffraction exhibited a small crystallite size and a good interfacial contact between the ZnS nanoparticles and the two-dimensional (2D) GR sheet, which were beneficial for the photocatalysis. When the content of the GR in the catalyst was 0.1%, the ZG0.1 sample exhibited the highest H2-production rate of 7.42 μmol h-1 g-1, eight times more than the pure ZnS sample. This high visible-light photocatalytic H2 production activity is attributed to the photosensitization of GR. Irradiated by visible light, the electrons photogenerated from GR transfer to the conduction band of ZnS to participate in the photocatalytic process. This study presents the visible-light photocatalytic activity of wide bandgap ZnS and its application in H2 evolution.

Visible light photocatalytic H2-production activity of wide band gap ZnS nanoparticles based on the photosensitization of grapheme.

PubMed

Wang, Faze; Zheng, Maojun; Zhu, Changqing; Zhang, Bin; Chen, Wen; Ma, Li; Shen, Wenzhong

2015-08-28

Visible light photocatalytic H(2) production from water splitting is considered an attractive way to solve the increasing global energy crisis in modern life. In this study, a series of zinc sulfide nanoparticles and graphene (GR) sheet composites were synthesized by a two-step hydrothermal method, which used zinc chloride, sodium sulfide, and graphite oxide (GO) as the starting materials. The as-prepared ZnS-GR showed highly efficient visible light photocatalytic activity in hydrogen generation. The morphology and structure of the composites obtained by transmission electron microscope and x-ray diffraction exhibited a small crystallite size and a good interfacial contact between the ZnS nanoparticles and the two-dimensional (2D) GR sheet,which were beneficial for the photocatalysis. When the content of the GR in the catalyst was 0.1%, the ZG0.1 sample exhibited the highest H(2)-production rate of 7.42 μmol h(−1) g(−1), eight times more than the pure ZnS sample. This high visible-light photocatalytic H(2) production activity is attributed to the photosensitization of GR. Irradiated by visible light, the electrons photogenerated from GR transfer to the conduction band of ZnS to participate in the photocatalytic process. This study presents the visible-light photocatalytic activity of wide bandgap ZnS and its application in H(2) evolution.

Silver Nanoparticle-Based Fluorescence-Quenching Lateral Flow Immunoassay for Sensitive Detection of Ochratoxin A in Grape Juice and Wine.

PubMed

Jiang, Hu; Li, Xiangmin; Xiong, Ying; Pei, Ke; Nie, Lijuan; Xiong, Yonghua

2017-02-28

A silver nanoparticle (AgNP)-based fluorescence-quenching lateral flow immunoassay with competitive format (cLFIA) was developed for sensitive detection of ochratoxin A (OTA) in grape juice and wine samples in the present study. The Ru(phen) 3 2 + -doped silica nanoparticles (RuNPs) were sprayed on the test and control line zones as background fluorescence signals. The AgNPs were designed as the fluorescence quenchers of RuNPs because they can block the exciting light transferring to the RuNP molecules. The proposed method exhibited high sensitivity for OTA detection, with a detection limit of 0.06 µg/L under optimized conditions. The method also exhibited a good linear range for OTA quantitative analysis from 0.08 µg/L to 5.0 µg/L. The reliability of the fluorescence-quenching cLFIA method was evaluated through analysis of the OTA-spiked red grape wine and juice samples. The average recoveries ranged from 88.0% to 110.0% in red grape wine and from 92.0% to 110.0% in grape juice. Meanwhile, less than a 10% coefficient variation indicated an acceptable precision of the cLFIA method. In summary, the new AgNP-based fluorescence-quenching cLFIA is a simple, rapid, sensitive, and accurate method for quantitative detection of OTA in grape juice and wine or other foodstuffs.

Silver Nanoparticle-Based Fluorescence-Quenching Lateral Flow Immunoassay for Sensitive Detection of Ochratoxin A in Grape Juice and Wine

PubMed Central

Jiang, Hu; Li, Xiangmin; Xiong, Ying; Pei, Ke; Nie, Lijuan; Xiong, Yonghua

2017-01-01

A silver nanoparticle (AgNP)-based fluorescence-quenching lateral flow immunoassay with competitive format (cLFIA) was developed for sensitive detection of ochratoxin A (OTA) in grape juice and wine samples in the present study. The Ru(phen)32+-doped silica nanoparticles (RuNPs) were sprayed on the test and control line zones as background fluorescence signals. The AgNPs were designed as the fluorescence quenchers of RuNPs because they can block the exciting light transferring to the RuNP molecules. The proposed method exhibited high sensitivity for OTA detection, with a detection limit of 0.06 µg/L under optimized conditions. The method also exhibited a good linear range for OTA quantitative analysis from 0.08 µg/L to 5.0 µg/L. The reliability of the fluorescence-quenching cLFIA method was evaluated through analysis of the OTA-spiked red grape wine and juice samples. The average recoveries ranged from 88.0% to 110.0% in red grape wine and from 92.0% to 110.0% in grape juice. Meanwhile, less than a 10% coefficient variation indicated an acceptable precision of the cLFIA method. In summary, the new AgNP-based fluorescence-quenching cLFIA is a simple, rapid, sensitive, and accurate method for quantitative detection of OTA in grape juice and wine or other foodstuffs. PMID:28264472

Particle morphology influence on mechanical and biocompatibility properties of injection molded Ti alloy powder.

PubMed

Gülsoy, H Özkan; Gülsoy, Nagihan; Calışıcı, Rahmi

2014-01-01

Titanium and Titanium alloys exhibits properties that are excellent for various bio-applications. Metal injection molding is a processing route that offers reduction in costs, with the added advantage of near net-shape components. Different physical properties of Titanium alloy powders, shaped and processed via injection molding can achieve high complexity of part geometry with mechanical and bioactivity properties, similar or superior to wrought material. This study describes that the effect of particle morphology on the microstructural, mechanical and biocompatibility properties of injection molded Ti-6Al-4V (Ti64) alloy powder for biomaterials applications. Ti64 powders irregular and spherical in shape were injection molded with wax based binder. Binder debinding was performed in solvent and thermal method. After debinding the samples were sintered under high vacuum. Metallographic studies were determined to densification and the corresponding microstructural changes. Sintered samples were immersed in a simulated body fluid (SBF) with elemental concentrations that were comparable to those of human blood plasma for a total period of 15 days. Both materials were implanted in fibroblast culture for biocompatibility evaluations were carried out. The results show that spherical and irregular powder could be sintered to a maximum theoretical density. Maximum tensile strength was obtained for spherical shape powder sintered. The tensile strength of the irregular shape powder sintered at the same temperature was lower due to higher porosity. Finally, mechanical tests show that the irregular shape powder has lower mechanical properties than spherical shape powder. The sintered irregular Ti64 powder exhibited better biocompatibility than sintered spherical Ti64 powder. Results of study showed that sintered spherical and irregular Ti64 powders exhibited high mechanical properties and good biocompatibility properties.

A copper ion-selective electrode with high selectivity prepared by sol-gel and coated wire techniques.

PubMed

Mazloum Ardakani, M; Salavati-Niasari, M; Khayat Kashani, M; Ghoreishi, S M

2004-03-01

A sol-gel electrode and a coated wire ion-selective poly(vinyl chloride) membrane, based on thiosemicarbazone as a neutral carrier, were successfully developed for the detection of Cu (II) in aqueous solutions. The sol-gel electrode and coated electrode exhibited linear response with Nernstian slopes of 29.2 and 28.1 mV per decade respectively, within the copper ion concentration ranges 1.0 x 10(-5) - 1.0 x 10(-1) M and 6.0 x 10(-6) - 1.0 x 10(-1) M for coated and sol-gel sensors. The coated and sol-gel electrodes show detection limits of 3.0 x 10(-6) and 6.0 x 10(-6) M respectively. The electrodes exhibited good selectivities for a number of alkali, alkaline earth, transition and heavy metal ions. The proposed electrodes have response times ranging from 10-50 s to achieve a 95% steady potential for Cu2+ concentration. The electrodes are suitable for use in aqueous solutions over a wide pH range (4-7.5). Applications of these electrodes for the determination of copper in real samples, and as an indicator electrode for potentiometric titration of Cu2+ ion using EDTA, are reported. The lifetimes of the electrodes were tested over a period of six months to investigate their stability. No significant change in the performance of the sol-gel electrode was observed over this period, but after two months the coated wire copper-selective electrode exhibited a gradual decrease in the slope. The selectivity of the sol-gel electrode was found to be better than that of the coated wire copper-selective electrode. Based on these results, a novel sol-gel copper-selective electrode is proposed for the determination of copper, and applied to real sample assays.

A highly sensitive monoclonal antibody based biosensor for quantifying 3-5 ring polycyclic aromatic hydrocarbons (PAHs) in aqueous environmental samples

PubMed Central

Li, Xin; Kaattari, Stephen L.; Vogelbein, Mary A.; Vadas, George G.; Unger, Michael A.

2016-01-01

Immunoassays based on monoclonal antibodies (mAbs) are highly sensitive for the detection of polycyclic aromatic hydrocarbons (PAHs) and can be employed to determine concentrations in near real-time. A sensitive generic mAb against PAHs, named as 2G8, was developed by a three-step screening procedure. It exhibited nearly uniformly high sensitivity against 3-ring to 5-ring unsubstituted PAHs and their common environmental methylated PAHs, with IC50 values between 1.68–31 μg/L (ppb). 2G8 has been successfully applied on the KinExA Inline Biosensor system for quantifying 3-5 ring PAHs in aqueous environmental samples. PAHs were detected at a concentration as low as 0.2 μg/L. Furthermore, the analyses only required 10 min for each sample. To evaluate the accuracy of the 2G8-based biosensor, the total PAH concentrations in a series of environmental samples analyzed by biosensor and GC-MS were compared. In most cases, the results yielded a good correlation between methods. This indicates that generic antibody 2G8 based biosensor possesses significant promise for a low cost, rapid method for PAH determination in aqueous samples. PMID:26925369

A comparative analysis of support vector machines and extreme learning machines.

PubMed

Liu, Xueyi; Gao, Chuanhou; Li, Ping

2012-09-01

The theory of extreme learning machines (ELMs) has recently become increasingly popular. As a new learning algorithm for single-hidden-layer feed-forward neural networks, an ELM offers the advantages of low computational cost, good generalization ability, and ease of implementation. Hence the comparison and model selection between ELMs and other kinds of state-of-the-art machine learning approaches has become significant and has attracted many research efforts. This paper performs a comparative analysis of the basic ELMs and support vector machines (SVMs) from two viewpoints that are different from previous works: one is the Vapnik-Chervonenkis (VC) dimension, and the other is their performance under different training sample sizes. It is shown that the VC dimension of an ELM is equal to the number of hidden nodes of the ELM with probability one. Additionally, their generalization ability and computational complexity are exhibited with changing training sample size. ELMs have weaker generalization ability than SVMs for small sample but can generalize as well as SVMs for large sample. Remarkably, great superiority in computational speed especially for large-scale sample problems is found in ELMs. The results obtained can provide insight into the essential relationship between them, and can also serve as complementary knowledge for their past experimental and theoretical comparisons. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development of a carbon-nanoparticle-coated stirrer for stir bar sorptive extraction by a simple carbon deposition in flame.

PubMed

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

2016-03-01

Stir bar sorptive extraction is an environmentally friendly microextraction technique based on a stir bar with various sorbents. A commercial stirrer is a good support, but it has not been used in stir bar sorptive extraction due to difficult modification. A stirrer was modified with carbon nanoparticles by a simple carbon deposition process in flame and characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry. A three-dimensional porous coating was formed with carbon nanoparticles. In combination with high-performance liquid chromatography, the stir bar was evaluated using five polycyclic aromatic hydrocarbons as model analytes. Conditions including extraction time and temperature, ionic strength, and desorption solvent were investigated by a factor-by-factor optimization method. The established method exhibited good linearity (0.01-10 μg/L) and low limits of quantification (0.01 μg/L). It was applied to detect model analytes in environmental water samples. No analyte was detected in river water, and five analytes were quantified in rain water. The recoveries of five analytes in two samples with spiked at 2 μg/L were in the range of 92.2-106% and 93.4-108%, respectively. The results indicated that the carbon nanoparticle-coated stirrer was an efficient stir bar for extraction analysis of some polycyclic aromatic hydrocarbons. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identification of phenolic acids and flavonoids in monofloral honey from Bangladesh by high performance liquid chromatography: determination of antioxidant capacity.

PubMed

Moniruzzaman, Mohammed; Yung An, Chua; Rao, Pasupuleti Visweswara; Hawlader, Mohammad Nurul Islam; Azlan, Siti Amirah Binti Mohd; Sulaiman, Siti Amrah; Gan, Siew Hua

2014-01-01

The aim of the present study was to characterize the phenolic acids, flavonoids, and antioxidant properties of monofloral honey collected from five different districts in Bangladesh. A new high performance liquid chromatography (HPLC) equipped with a UV detector method was developed for the identification of the phenolic acids and flavonoids. A total of five different phenolic acids were identified, with the most abundant being caffeic acid, benzoic acid, gallic acid, followed by chlorogenic acid and trans-cinnamic acid. The flavonoids, kaempferol, and catechin were most abundant, followed by myricetin and naringenin. The mean moisture content, total sugar content, and color characteristics of the honey samples were 18.36 ± 0.95%, 67.40 ± 5.63 g/100 g, and 129.27 ± 34.66 mm Pfund, respectively. The mean total phenolic acids, total flavonoid content, and proline content were 199.20 ± 135.23, 46.73 ± 34.16, and 556.40 ± 376.86 mg/kg, respectively, while the mean FRAP values and DPPH radical scavenging activity were 327.30 ± 231.87 μM Fe (II)/100 g and 36.95 ± 20.53%, respectively. Among the different types of honey, kalijira exhibited the highest phenolics and antioxidant properties. Overall, our study confirms that all the investigated honey samples are good sources of phenolic acids and flavonoids with good antioxidant properties.

A novel enzymatic glucose sensor based on Pt nanoparticles-decorated hollow carbon spheres-modified glassy carbon electrode

NASA Astrophysics Data System (ADS)

Luhana, Charles; Bo, Xiang-Jie; Ju, Jian; Guo, Li-Ping

2012-10-01

A new glucose biosensor was developed based on hollow carbon spheres decorated with platinum nanoparticles (Pt/HCSs)-modified glassy carbon electrode immobilized with glucose oxidase (GOx) with the help of Nafion. The Pt nanoparticles were well dispersed on the HCSs with an average size of 2.29 nm. The detection of glucose was achieved via electrochemical detection of the enzymatically liberated H2O2 at +0.5 V versus Ag/AgCl at physiologic pH of 7.4. The Pt/HCSs-modified electrode exhibited excellent electrocatalytic activities toward both the oxidation and reduction of H2O2. The glucose biosensor showed good electrocatalytic performance in terms of high sensitivity (4.1 μA mM-1), low detection limit (1.8 μM), fast response time <3 s, and wide linear range (0.04-8.62 mM). The apparent Michaelis-Menten constant ( K m) and the maximum current density ( i max) values for the biosensor were 10.94 mM and 887 μA cm-2 respectively. Furthermore, this biosensor showed an acceptable reproducibility and high stability. The interfering signals from ascorbic acid and uric acid at concentration levels normally found in human blood were not much compared with the response to glucose. Blood serum samples were also tested with this biosensor and a good recovery was achieved for the two spiked serum samples.

Multianalyte imaging in one-shot format sensors for natural waters.

PubMed

Lapresta-Fernández, A; Huertas, Rafael; Melgosa, Manuel; Capitán-Vallvey, L F

2009-03-23

A one-shot multisensor based on ionophore-chromoionophore chemistry for optical monitoring of potassium, magnesium and hardness in water is presented. The analytical procedure uses a black and white non-cooled CCD camera for image acquisition of the one-shot multisensor after reaction, followed by data treatment for quantitation using the grey value pixel average from a defined region of interest from each sensing area to build the analytical parameter 1-alpha. In optimised experimental conditions, the procedure shows a large linear range, up to 6 orders using the linearised model and good detection limits: 9.92 x 10(-5)mM, 1.86 x 10(-3)mM and 1.30 x 10(-2)mgL(-1) of CaCO(3) for potassium, magnesium and hardness, respectively. This analysis system exhibits good precision in terms of relative standard deviation (RSD%) from 2.3 to 3.8 for potassium, from 5.0 to 6.8 for magnesium and from 5.4 to 5.9 for hardness. The trueness of this multisensor procedure was demonstrated comparing it with results obtained by a DAD spectrophotometer used as a reference. Finally, it was satisfactorily applied to the analysis of these analytes in miscellaneous samples, such as water and beverage samples from different origins, validating the results against atomic absorption spectrometry (AAS) as the reference procedure.

Eggshell membrane-based biotemplating of mixed hemimicelle/admicelle as a solid-phase extraction adsorbent for carcinogenic polycyclic aromatic hydrocarbons.

PubMed

Wang, Weidong; Chen, Bo; Huang, Yuming

2014-08-13

A new solid-phase extraction (SPE) format was demonstrated, based on eggshell membrane (ESM) templating of the mixed hemimicelle/admicelle of linear alkylbenzenesulfonates (LAS) as an adsorbent for the enrichment of carcinogenic polycyclic aromatic hydrocarbons (PAHs) in environmental aqueous samples. The LAS mixed hemimicelle/admicelle formation and SPE of the target PAHs were conducted simultaneously by adding the organic target and LAS through a column filled with 500 mg of ESM. The effect of various factors, including LAS concentration, solution pH, ionic strength, and humic acid concentration on the recoveries of PAHs were investigated and optimized. The results showed that LAS concentration and solution pH had obvious effect on extraction of PAHs, and the recoveries of PAHs compounds decreased in the presence of salt and humic acid. Under the optimized analytical conditions, the present method could respond down to 0.1-8.6 ng/L PAHs with a linear calibration ranging from 0.02 to 10 μg/L, showing a good PAHs enrichment ability with high sensitivity. The developed method was used satisfactorily for the detection of PAHs in environmental water samples. The mixed hemimicelle/admicelle adsorbent exhibited high extraction efficiency to PAHs and good selectivity with respect to natural organic matter and was advantageous over commercial C₁₈ adsorbent, for example, high extraction yield, high breakthrough volume, and easy regeneration.

Relationship between surface property and catalytic application of amorphous NiP/Hβ catalyst for n-hexane isomerization

NASA Astrophysics Data System (ADS)

Chen, Jinshe; Duan, Zunbin; Song, Zhaoyang; Zhu, Lijun; Zhou, Yulu; Xiang, Yuzhi; Xia, Daohong

2017-12-01

The amorphous NiP nanoparticles were synthesized and a novel amorphous NiP/Hβ catalyst was prepared successfully further. Due to the superior surface property of amorphous NiP/Hβ catalyst, it exhibited good catalytic application for n-hexane isomerization. The catalytic activity of amorphous NiP/Hβ catalyst was close to that of the prepared Pt/Hβ sample, and better than that of commercial catalyst and crystalline Ni2P/Hβ catalyst. What's more, the amorphous NiP/Hβ catalyst shows high resistance to different sulfur compounds and water on account of its unique surface property. The effect of loading amounts on surface property and catalytic performance was investigated, and the structure-function relationship among them was studied ulteriorly. The results demonstrate that loading amounts have effect on textural property and surface acid property, which further affect the catalytic performance. The 10 wt.% NiP/Hβ sample has appropriate pore structure and acid property with uniformly dispersed NiP nanoparticles on surface, which is helpful for providing suitable synergistic effect. The effects of reaction conditions on surface reactions and the mechanism for n-hexane isomerization were investigated further. Based on these results, the amorphous NiP/Hβ catalyst with superior surface property probably pavesa way to overcome the drawbacks of traditional noble metal catalyst, which shows good catalytic application prospects.

l-Cysteine-modified silver-functionalized silica-based material as an efficient solid-phase extraction adsorbent for the determination of bisphenol A.

PubMed

Li, Yuanyuan; Zhu, Nan; Li, Bingxiang; Chen, Tong; Ma, Yulong; Li, Qiang

2018-02-01

A new silver-functionalized silica-based material with a core-shell structure based on silver nanoparticle-coated silica spheres was synthesized, and silver nanoparticles were modified using strongly bound l-cysteine. l-Cysteine-silver@silica was characterized by scanning electron microscopy and FTIR spectroscopy. Then, a solid-phase extraction method based on l-cysteine-silver@silica was developed and successfully used for bisphenol A determination prior to HPLC analysis. The results showed that the l-cysteine-silver@silica as an adsorbent exhibited good enrichment capability for bisphenol A, and the maximum adsorption saturation was 20.93 mg/g. Moreover, a short adsorption equilibrium time was obtained due to the presence of silver nanoparticles on the surface of the silica. The extraction efficiencies were then optimized by varying the eluents and pH. Under the optimized conditions, good linearity for bisphenol A was obtained in the range from 0.4 to 4.0 μM (R 2  > 0.99) with a low limit of detection (1.15 ng/mL). The spiked recoveries from tap water and milk samples were satisfactory (85-102%) with relative standard deviations below 5.2% (n = 3), which indicated that the method was suitable for the analysis of bisphenol A in complex samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Intermolecular ionic cross-linked sulfonated poly(ether ether ketone) membranes containing diazafluorene for direct methanol fuel cell applications

NASA Astrophysics Data System (ADS)

Liang, Yu; Gong, Chenliang; Qi, Zhigang; Li, Hui; Wu, Zhongying; Zhang, Yakui; Zhang, Shujiang; Li, Yanfeng

2015-06-01

A series of novel ionic cross-linking sulfonated poly(ether ether ketone) (SPEEK) membranes containing the diazafluorene functional group are synthesized to reduce the swelling ratio and methanol permeability for direct methanol fuel cell (DMFC) applications. The ionic cross-linking is realized by the interaction between sulfonic acid groups and pyridyl in diazafluorene. The prepared membranes exhibit good mechanical properties, adequate thermal stability, good oxidative stability, appropriate water uptake and low swelling ratio. Moreover, the ionic cross-linked membranes exhibit lower methanol permeability in the range between 0.56 × 10-7 cm2 s-1 and 1.8 × 10-7 cm2 s-1, which is lower than Nafion 117, and they exhibit higher selectivity than Nafion 117 at 30 °C on the basis of applicable proton conductivity.

Synthesis and biological screening of 2'-aryl/benzyl-2-aryl-4-methyl-4',5-bithiazolyls as possible anti-tubercular and antimicrobial agents.

PubMed

Abhale, Yogita K; Sasane, Amit V; Chavan, Abhijit P; Deshmukh, Keshav K; Kotapalli, Sudha Sravanti; Ummanni, Ramesh; Sayyad, Sadikali F; Mhaske, Pravin C

2015-04-13

A series of 2'-aryl/benzyl-2-aryl-4-methyl-4',5-bithiazolyl derivatives, 25-64 were synthesized and evaluated for inhibitory activity against Mycobacterium smegmatis MC(2) 155 strain and antimicrobial activities against four pathogenic bacteria Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Proteus vulgaris. Among them, compounds 40, 49, 50, and 54 exhibited moderate to good inhibition on the growth of the bacteria Mycobacterium smegmatis at the concentration of 30 μM. Compounds 26, 40, 44, 54 and 56 exhibited moderate to good antibacterial activity. Compound 5-(2'-(4-fluorobenzyl)thiazol-4'-yl)-2-(4-fluorophenyl)-4-methyl-thiazole (54) exhibited both antitubercular as well as antimicrobial activity against all tested strains. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Morphology-controlled synthesis and novel microwave electromagnetic properties of hollow urchin-like chain Fe-doped MnO 2 under 10 T high magnetic field

NASA Astrophysics Data System (ADS)

Yuping, Duan; Jia, Zhang; Hui, Jing; Shunhua, Liu

2011-05-01

Fe-doped MnO 2 with a hollow sea urchin-like ball chain shape was first synthesized under a high magnetic field of 10 T. The formation mechanism was investigated and discussed in detail. The synthesized samples were characterized by XRD, SEM, TEM, EMPA, and vector network analysis. By doping MnO 2 with Fe, the relative complex permittivity of MnO 2 and its corresponding loss tangent clearly decreases, but its relative complex permeability and its corresponding loss tangent markedly increases. Moreover, the theoretically calculated values of reflection loss show that with increasing the Fe content, the as-prepared Fe-doped MnO 2 exhibits good microwave absorption capability.

The MUSE-Wide survey: a measurement of the Ly α emitting fraction among z > 3 galaxies

NASA Astrophysics Data System (ADS)

Caruana, Joseph; Wisotzki, Lutz; Herenz, Edmund Christian; Kerutt, Josephine; Urrutia, Tanya; Schmidt, Kasper Borello; Bouwens, Rychard; Brinchmann, Jarle; Cantalupo, Sebastiano; Carollo, Marcella; Diener, Catrina; Drake, Alyssa; Garel, Thibault; Marino, Raffaella Anna; Richard, Johan; Saust, Rikke; Schaye, Joop; Verhamme, Anne

2018-01-01

We present a measurement of the fraction of Lyman α (Ly α) emitters (XLy α) amongst HST continuum-selected galaxies at 3 < z < 6 with the Multi-Unit Spectroscopic Explorer (MUSE) on the VLT. Making use of the first 24 MUSE-Wide pointings in GOODS-South, each having an integration time of 1 h, we detect 100 Ly α emitters and find XLy α ≳ 0.5 for most of the redshift range covered, with 29 per cent of the Ly α sample exhibiting rest equivalent widths (rest-EWs) ≤ 15 Å. Adopting a range of rest-EW cuts (0-75 Å), we find no evidence of a dependence of XLy α on either redshift or ultraviolet luminosity.

Gold nanorods-silicone hybrid material films and their optical limiting property

NASA Astrophysics Data System (ADS)

Li, Chunfang; Qi, Yanhai; Hao, Xiongwen; Peng, Xue; Li, Dongxiang

2015-10-01

As a kind of new optical limiting materials, gold nanoparticles have optical limiting property owing to their optical nonlinearities induced by surface plasmon resonance (SPR). Gold nanorods (GNRs) possess transversal SPR absorption and tunable longitudinal SPR absorption in the visible and near-infrared region, so they can be used as potential optical limiting materials against tunable laser pulses. In this letter, GNRs were prepared using seed-mediated growth method and surface-modified by silica coating to obtain good dispersion in polydimethylsiloxane prepolymers. Then the silicone rubber films doped with GNRs were prepared after vulcanization, whose optical limiting property and optical nonlinearity were investigated. The silicone rubber samples doped with more GNRs were found to exhibit better optical limiting performance.

Surface phenomena of hydroxyapatite film on the nanopore formed Ti-29Nb-xZr alloy by anodization for bioimplants.

PubMed

Kim, Eun-Ju; Jeong, Yong-Hoon; Choe, Han-Cheol

2013-03-01

In this study, surface phenomena of hydroxyapatite (HA) film on the nanopore formed Ti-29Nb-xZr alloy by anodization for bioimplants have been investigated by electron beam physical vapor deposition (EB-PVD), field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), potentiostat and contact angle. The microstructure of Ti-29Nb-xZr alloys exhibited equiaxed structure and alpha" phase decreased, whereas beta phase increased as Zr content increased. The increment of Zr contents in HA coated nanotubular Ti-29Nb-xZr alloys showed good corrosion potential in 0.9% NaCI solution. The wettability of HA coated nanotubular surface was higher than that of non-coated samples.

Highly fluorescent carbon quantum dots as nanoprobes for sensitive and selective determination of mercury (II) in surface waters

NASA Astrophysics Data System (ADS)

Hua, Jianhao; Yang, Jian; Zhu, Yan; Zhao, Chunxi; Yang, Yaling

2017-12-01

A novel carbon quantum dots (CQDs) was successfully prepared through one-step green hydrothermal method using polyacrylamide as carbon source. The prepared CQDs were characterized using TEM, XRD, XPS, FT-IR, UV-Vis, and fluorescence spectroscopy. The CQDs was demonstrated as nanoprobes for mercury ion detection, moreover, it demonstrated excitation-dependent and superior stability in acidic and alkaline media. Besides, the probe exhibited a good linearity range (0.25-50 μM) and a low detection limit (13.48 nM). These attractive properties indicated that this novel CQDs can adapt to a variety of complex pH environment, which had extensive prospect and promising application for detection of mercury ions in complex water samples.

Asymmetrical flow field-flow fractionation with multi-angle light scattering and quasi-elastic light scattering for characterization of polymersomes: comparison with classical techniques.

PubMed

Till, Ugo; Gaucher-Delmas, Mireille; Saint-Aguet, Pascale; Hamon, Glenn; Marty, Jean-Daniel; Chassenieux, Christophe; Payré, Bruno; Goudounèche, Dominique; Mingotaud, Anne-Françoise; Violleau, Frédéric

2014-12-01

Polymersomes formed from amphiphilic block copolymers, such as poly(ethyleneoxide-b-ε-caprolactone) (PEO-b-PCL) or poly(ethyleneoxide-b-methylmethacrylate), were characterized by asymmetrical flow field-flow fractionation coupled with quasi-elastic light scattering (QELS), multi-angle light scattering (MALS), and refractive index detection, leading to the determination of their size, shape, and molecular weight. The method was cross-examined with more classical ones, like batch dynamic and static light scattering, electron microscopy, and atomic force microscopy. The results show good complementarities between all the techniques; asymmetrical flow field-flow fractionation being the most pertinent one when the sample exhibits several different types of population.

Electrospun bismuth ferrite nanofibers for potential applications in ferroelectric photovoltaic devices.

PubMed

Fei, Linfeng; Hu, Yongming; Li, Xing; Song, Ruobing; Sun, Li; Huang, Haitao; Gu, Haoshuang; Chan, Helen L W; Wang, Yu

2015-02-18

Bismuth ferrite (BFO) nanofibers were synthesized via a sol-gel-based electrospinning process followed by thermal treatment. The influences of processing conditions on the final structure of the samples were investigated. Nanofibers prepared under optimized conditions were found to have a perovskite structure with good quality of crystallization and free of impurity phase. Ferroelectric and piezoelectric responses were obtained from individual nanofiber measured on a piezoelectric force microscope. A prototype photovoltaic device using laterally aligned BFO nanofibers and interdigital electrodes was developed and its performance was examined on a standard photovoltaic system. The BFO nanofibers were found to exhibit an excellent ferroelectric photovoltaic property with the photocurrent several times larger than the literature data obtained on BFO thin films.

Low-loss electromagnetic composites for RF and microwave applications.

PubMed

Wang, Hong; Yang, Haibo; Xiang, Feng; Yao, Xi

2011-09-01

Low-loss electromagnetic composites with high permittivity and permeability will benefit the miniaturization and multifunctional of RF devices. A kind of low-loss dielectric-magnetic ceramic-ceramic composite was developed by hybrid processing technology with the goal of integrating the dielectric properties and magnetic properties. The hybrid processing technology exhibits the advantage of lowered sintering temperatures for the composites while retaining good microstructure and high performance. By introducing elastomer as matrix, a kind of flexible low-loss dielectric-magnetic ceramic-polymer composite was prepared and studied. The obtained flexible dielectric-magnetic ceramic-polymer composite exhibited low loss and good mechanical properties. The results show good effects on lowering the dielectric loss and extending the cut-off magnetic frequency of the electromagnetic composite. Methods for tailoring the properties of the multifunctional composites were proposed and discussed.

Discounting of Delayed Rewards Is Not Hyperbolic

ERIC Educational Resources Information Center

Luhmann, Christian C.

2013-01-01

Delay discounting refers to decision-makers' tendency to value immediately available goods more than identical goods available only after some delay. In violation of standard economic theory, decision-makers frequently exhibit dynamic inconsistency; their preferences change simply due to the passage of time. The standard explanation for this…

Self-Supporting, Hydrophobic, Ionic Liquid-Based Reference Electrodes Prepared by Polymerization-Induced Microphase Separation.

PubMed

Chopade, Sujay A; Anderson, Evan L; Schmidt, Peter W; Lodge, Timothy P; Hillmyer, Marc A; Bühlmann, Philippe

2017-10-27

Interfaces of ionic liquids and aqueous solutions exhibit stable electrical potentials over a wide range of aqueous electrolyte concentrations. This makes ionic liquids suitable as bridge materials that separate in electroanalytical measurements the reference electrode from samples with low and/or unknown ionic strengths. However, methods for the preparation of ionic liquid-based reference electrodes have not been explored widely. We have designed a convenient and reliable synthesis of ionic liquid-based reference electrodes by polymerization-induced microphase separation. This technique allows for a facile, single-pot synthesis of ready-to-use reference electrodes that incorporate ion conducting nanochannels filled with either 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-dodecyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide as ionic liquid, supported by a mechanically robust cross-linked polystyrene phase. This synthesis procedure allows for the straightforward design of various reference electrode geometries. These reference electrodes exhibit a low resistance as well as good reference potential stability and reproducibility when immersed into aqueous solutions varying from deionized, purified water to 100 mM KCl, while requiring no correction for liquid junction potentials.

Tracking metal ions with polypyrrole thin films adhesively bonded to diazonium-modified flexible ITO electrodes.

PubMed

Lo, Momath; Diaw, Abdou K D; Gningue-Sall, Diariatou; Aaron, Jean-Jacques; Oturan, Mehmet A; Chehimi, Mohamed M

2018-05-09

Adhesively bonded polypyrrole thin films doped with benzene sulfonic acid (BSA) were electrodeposited on aminobenzenediazonium-modified flexible ITO electrodes and further employed for the detection of Pb 2+ , Cu 2+ , and Cd 2+ metal ions in aqueous medium. The aminophenyl (AP) adhesive layer was grafted to ITO by electroreduction of the in situ generated parent diazonium compound. Polypyrrole (PPy) thin films exhibited remarkable adhesion to aminophenyl (ITO-AP). The strongly adherent polypyrrole films exhibited excellent electroactivity in the doped state with BSA which itself served to chelate the metal ions in aqueous medium. The surface of the resulting, modified flexible electrode was characterized by XPS, SEM, and electrochemical methods. The ITO-AP-PPy electrodes were then used for the simultaneous detection of Cu 2+ , Cd 2+ , and Pb 2+ by differential pulse voltammetry (DPV). The detection limits were 11.1, 8.95, and 0.99 nM for Cu 2+ , Cd 2+ , and Pb 2+ , respectively. In addition, the modified electrodes displayed a good reproducibility, making them suitable for the determination of heavy metals in real wastewater samples.

A novel voltammetric sensor for ascorbic acid based on molecularly imprinted poly(o-phenylenediamine-co-o-aminophenol).

PubMed

Kong, Yong; Shan, Xueling; Ma, Jianfeng; Chen, Meilan; Chen, Zhidong

2014-01-27

A molecularly imprinted copolymer, poly(o-phenylenediamine-co-o-aminophenol) (PoPDoAP), was prepared as a new ascorbic acid (AA) sensor. The copolymer was synthesized by incorporation of AA as template molecules during the electrochemical copolymerization of o-phenylenediamine and o-aminophenol, and complementary sites were formed after the copolymer was electrochemically reduced in ammonium aqueous solution. The molecularly imprinted copolymer sensor exhibited a high sensitivity and selectivity toward AA. Differential pulse voltammograms (DPVs) showed a linear concentration range of AA from 0.1 to 10 mM, and the detection limit was calculated to be 36.4 μM. Compared to conventional polyaniline-based AA sensors, the analytical performance of the imprinted copolymer sensor was improved due to the broadened usable pH range of PoPDoAP (from pH 1.0 to pH 8.0). The sensor also exhibited a good reproducibility and stability. And it has been successfully applied in the determination of AA in real samples, including vitamin C tablet and orange juices, with satisfactory results. Copyright © 2013 Elsevier B.V. All rights reserved.

EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid.

PubMed

Kanchana, P; Sekar, C

2014-09-01

Hydroxyapatite nanoparticles have been synthesized using EDTA as organic modifier by a simple microwave irradiation method and its application for the selective determination of uric acid (UA) has been demonstrated. Electrochemical behavior of uric acid at HA nanoparticle modified glassy carbon electrode (E-HA/GCE) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometry. The E-HA modified electrode exhibits efficient electrochemical activity towards uric acid sensing without requiring enzyme or electron mediator. Amperometry studies revealed that the fabricated electrode has excellent sensitivity for uric acid with the lowest detection limit of 142 nM over a wide concentration range from 1 × 10(-7) to 3 × 10(-5)M. Moreover, the studied E-HA modified GC electrode exhibits a good reproducibility and long-term stability and an admirable selectivity towards the determination of UA even in the presence of potential interferents. The analytical performance of this sensor was evaluated for the detection of uric acid in human urine and blood serum samples. Copyright © 2014. Published by Elsevier B.V.

Graphene-ZIF8 composite material as stationary phase for high-resolution gas chromatographic separations of aliphatic and aromatic isomers.

PubMed

Yang, Xiaohong; Li, Changxia; Qi, Meiling; Qu, Liangti

2016-08-19

This work presents the separation performance of graphene-ZIF8 (G-Z) composite material as stationary phase for capillary gas chromatography (GC). The G-Z stationary phase achieved high column efficiency of 5000 plates/m determined by n-dodecane (k=1.22) at 120°C and showed weakly polar nature. Importantly, it exhibited high selectivity and resolving capability for branched alkane isomers and aromatic positional isomers, showing clear advantages over the reported neat graphene and ZIF8. In addition, it attained high resolution for geometric cis-/trans-isomers. The G-Z column exhibited good column thermal stability up to 300°C and column repeatability with RSD values of retention times in the range of 0.01-0.19% for intra-day, 0.05-0.88% for inter-day and 0.66-5.6% for between-column, respectively, Moreover, the G-Z column was employed for the determination of minor impurity isomers in real reagent samples, which demonstrates its promising potential in GC applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Secondary Psychometric Examination of the Dimensional Obsessive-Compulsive Scale: Classical Testing, Item Response Theory, and Differential Item Functioning.

PubMed

Thibodeau, Michel A; Leonard, Rachel C; Abramowitz, Jonathan S; Riemann, Bradley C

2015-12-01

The Dimensional Obsessive-Compulsive Scale (DOCS) is a promising measure of obsessive-compulsive disorder (OCD) symptoms but has received minimal psychometric attention. We evaluated the utility and reliability of DOCS scores. The study included 832 students and 300 patients with OCD. Confirmatory factor analysis supported the originally proposed four-factor structure. DOCS total and subscale scores exhibited good to excellent internal consistency in both samples (α = .82 to α = .96). Patient DOCS total scores reduced substantially during treatment (t = 16.01, d = 1.02). DOCS total scores discriminated between students and patients (sensitivity = 0.76, 1 - specificity = 0.23). The measure did not exhibit gender-based differential item functioning as tested by Mantel-Haenszel chi-square tests. Expected response options for each item were plotted as a function of item response theory and demonstrated that DOCS scores incrementally discriminate OCD symptoms ranging from low to extremely high severity. Incremental differences in DOCS scores appear to represent unbiased and reliable differences in true OCD symptom severity. © The Author(s) 2014.

Sample-Based Surface Coloring

PubMed Central

Bürger, Kai; Krüger, Jens; Westermann, Rüdiger

2011-01-01

In this paper, we present a sample-based approach for surface coloring, which is independent of the original surface resolution and representation. To achieve this, we introduce the Orthogonal Fragment Buffer (OFB)—an extension of the Layered Depth Cube—as a high-resolution view-independent surface representation. The OFB is a data structure that stores surface samples at a nearly uniform distribution over the surface, and it is specifically designed to support efficient random read/write access to these samples. The data access operations have a complexity that is logarithmic in the depth complexity of the surface. Thus, compared to data access operations in tree data structures like octrees, data-dependent memory access patterns are greatly reduced. Due to the particular sampling strategy that is employed to generate an OFB, it also maintains sample coherence, and thus, exhibits very good spatial access locality. Therefore, OFB-based surface coloring performs significantly faster than sample-based approaches using tree structures. In addition, since in an OFB, the surface samples are internally stored in uniform 2D grids, OFB-based surface coloring can efficiently be realized on the GPU to enable interactive coloring of high-resolution surfaces. On the OFB, we introduce novel algorithms for color painting using volumetric and surface-aligned brushes, and we present new approaches for particle-based color advection along surfaces in real time. Due to the intermediate surface representation we choose, our method can be used to color polygonal surfaces as well as any other type of surface that can be sampled. PMID:20616392

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids

PubMed Central

Zheng, Xiaojiao; Qiu, Yunping; Zhong, Wei; Baxter, Sarah; Su, Mingming; Li, Qiong; Xie, Guoxiang; Ore, Brandon M.; Qiao, Shanlei; Spencer, Melanie D.; Zeisel, Steven H.; Zhou, Zhanxiang; Zhao, Aihua; Jia, Wei

2013-01-01

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and inter-day (within 7 days) precision (< 10%), and good stability (< 20%) within 4 days at room temperature (23–25 °C), or 7 days when stored at −20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistics analysis of the concentrations of these target metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research. PMID:23997757

A High-Precision Counter Using the DSP Technique

DTIC Science & Technology

2004-09-01

DSP is not good enough to process all the 1-second samples. The cache memory is also not sufficient to store all the sampling data. So we cut the...sampling number in a cycle is not good enough to achieve an accuracy less than 2×10-11. For this reason, a correlation operation is performed for... not good enough to process all the 1-second samples. The cache memory is also not sufficient to store all the sampling data. We will solve this

Non-enzymatic detection of glucose using poly(azure A)-nickel modified glassy carbon electrode.

PubMed

Liu, Tong; Luo, Yiqun; Zhu, Jiaming; Kong, Liyan; Wang, Wen; Tan, Liang

2016-08-15

A simple, sensitive and selective non-enzymatic glucose sensor was constructed in this paper. The poly(azure A)-nickel modified glassy carbon electrode was successfully fabricated by the electropolymerization of azure A and the adsorption of Ni(2+). The Ni modified electrode, which was characterized by scanning electron microscope, cyclic voltammetry, electrochemical impedance spectra and X-ray photoelectron spectroscopy measurements, respectively, displayed well-defined current responses of the Ni(III)/Ni(II) couple and showed a good activity for electrocatalytic oxidation of glucose in alkaline medium. Under the optimized conditions, the developed sensor exhibited a broad linear calibration range of 5 μM-12mM for quantification of glucose and a low detection limit of 0.64μM (3σ). The excellent analytical performance including simple structure, fast response time, good anti-interference ability, satisfying stability and reliable reproducibility were also found from the proposed amperometric sensor. The results were satisfactory for the determination of glucose in human serum samples as comparison to those from a local hospital. Copyright © 2016 Elsevier B.V. All rights reserved.

Combinatorial screening of potentiometric Pb(II) sensors from polysulfoaminoanthraquinone solid ionophore.

PubMed

Huang, Mei-Rong; Ding, Yong-Bo; Li, Xin-Gui

2014-03-10

A potentiometric Pb(II)-selective sensor was fabricated by a combinatorial screening of electrically conducting polysulfoaminoanthraquinone (PSA) nanoparticles as a solid ionophore, ion exchangers (oleic acid (OA) and NaTPB), plasticizers in a polyvinyl chloride (PVC) matrix, membrane thickness, inner filling ion species, and concentration. The membrane sensor with the composition of PSA/PVC/DOP (dioctyl phthalate)/OA (1.0:33:61:5.0) exhibited the best performance, including a slope of 29.3 mV decade(-1) in the concentration range 10(-6.3)-10(-1.6) M, detection limit of 1.6 × 10(-7) M, response time of 16 s, lifetime of five months, and good response reversibility. The proposed sensor has demonstrated good selectivity for Pb(II) over other monovalent, divalent and trivalent interfering ions, and could be used in a pH range of 3.62-5.22. The Pb(II) sensor has been successfully applied for the determination of Pb(II) concentration in real-world samples and also as an indicator electrode for potentiometric titration of lead ions.

An optical chemical sensor for thorium (IV) determination based on thorin.

PubMed

Rastegarzadeh, S; Pourreza, N; Saeedi, I

2010-01-15

A selective method for the determination of thorium (IV) using an optical sensor is described. The sensing membrane is prepared by immobilization of thorin-methyltrioctylammonium ion pair on triacetylcellulose polymer. The sensor produced a linear response for thorium (IV) concentration in the range of 6.46 x 10(-6) to 9.91 x 10(-5)mol L(-1) with detection limit of 1.85 x 10(-6)mol L(-1). The regeneration of optode was accomplished completely at a short time (less than 20s) with 0.1 mol L(-1) of oxalate ion solution. The relative standard deviation for ten replicate measurements of 2.15 x 10(-5) and 8.62 x 10(-5)mol L(-1) of thorium was 2.71 and 1.65%, respectively. The optode membrane exhibits good selectivity for thorium (IV) over several other ionic species and are comparable to those obtained in case of spectrophotometric determination of thorium using thorin in solution. A good agreement with the ICP-MS and spiked method was achieved when the proposed optode was applied to the determination of thorium (IV) in dust and water samples.

A ruthenium(II) complex as turn-on Cu(II) luminescent sensor based on oxidative cyclization mechanism and its application in vivo

NASA Astrophysics Data System (ADS)

Zhang, Yunfei; Liu, Zonglun; Yang, Kui; Zhang, Yi; Xu, Yongqian; Li, Hongjuan; Wang, Chaoxia; Lu, Aiping; Sun, Shiguo

2015-02-01

Copper ions play a vital role in a variety of fundamental physiological processes not only in human beings and plants, but also for extensive insects and microorganisms. In this paper, a novel water-soluble ruthenium(II) complex as a turn-on copper(II) ions luminescent sensor based on o-(phenylazo)aniline was designed and synthesized. The azo group would undergo a specific oxidative cyclization reaction with copper(II) ions and turn into high luminescent benzotriazole, triggering significant luminescent increasements which were linear to the concentrations of copper(II) ions. The sensor distinguished by its high sensitivity (over 80-fold luminescent switch-on response), good selectivity (the changes of the emission intensity in the presence of other metal ions or amino acids were negligible) and low detection limit (4.42 nM) in water. Moreover, the copper(II) luminescent sensor exhibited good photostability under light irradiation. Furthermore, the applicability of the proposed sensor in biological samples assay was also studied and imaged copper(II) ions in living pea aphids successfully.

Determination of parabens using two microextraction methods coupled with capillary liquid chromatography-UV detection.

PubMed

Chen, Chen-Wen; Hsu, Wen-Chan; Lu, Ya-Chen; Weng, Jing-Ru; Feng, Chia-Hsien

2018-02-15

Parabens are common preservatives and environmental hormones. As such, possible detrimental health effects could be amplified through their widespread use in foods, cosmetics, and pharmaceutical products. Thus, the determination of parabens in such products is of particular importance. This study explored vortex-assisted dispersive liquid-liquid microextraction techniques based on the solidification of a floating organic drop (VA-DLLME-SFO) and salt-assisted cloud point extraction (SA-CPE) for paraben extraction. Microanalysis was performed using a capillary liquid chromatography-ultraviolet detection system. These techniques were modified successfully to determine four parabens in 19 commercial products. The regression equations of these parabens exhibited good linearity (r 2 =0.998, 0.1-10μg/mL), good precision (RSD<5%) and accuracy (RE<5%), reduced reagent consumption and reaction times (<6min), and excellent sample versatility. VA-DLLME-SFO was also particularly convenient due to the use of a solidified extract. Thus, the VA-DLLME-SFO technique was better suited to the extraction of parabens from complex matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.

Polypyrrole-polyoxometalate/reduced graphene oxide ternary nanohybrids for flexible, all-solid-state supercapacitors.

PubMed

Chen, Yuyun; Han, Min; Tang, Yujia; Bao, Jianchun; Li, Shunli; Lan, Yaqian; Dai, Zhihui

2015-08-11

Novel polypyrrole-polyoxometalate/reduced graphene oxide ternary nanohybrids (TNHs) are synthesized via a one-pot redox relay strategy. The TNHs exhibit high areal specific capacitance (2.61 mF cm(-2)), and the fabricated solid device also exhibits good rate capability, excellent flexibility and mechanical stability.

34 CFR 101.74 - Exhibits.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 34 Education 1 2010-07-01 2010-07-01 false Exhibits. 101.74 Section 101.74 Education Regulations of the Offices of the Department of Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION... objection thereto is filed prior to the hearing or unless good cause is shown at the hearing for failure to...

The medial prefrontal cortex exhibits money illusion

PubMed Central

Weber, Bernd; Rangel, Antonio; Wibral, Matthias; Falk, Armin

2009-01-01

Behavioral economists have proposed that money illusion, which is a deviation from rationality in which individuals engage in nominal evaluation, can explain a wide range of important economic and social phenomena. This proposition stands in sharp contrast to the standard economic assumption of rationality that requires individuals to judge the value of money only on the basis of the bundle of goods that it can buy—its real value—and not on the basis of the actual amount of currency—its nominal value. We used fMRI to investigate whether the brain's reward circuitry exhibits money illusion. Subjects received prizes in 2 different experimental conditions that were identical in real economic terms, but differed in nominal terms. Thus, in the absence of money illusion there should be no differences in activation in reward-related brain areas. In contrast, we found that areas of the ventromedial prefrontal cortex (vmPFC), which have been previously associated with the processing of anticipatory and experienced rewards, and the valuation of goods, exhibited money illusion. We also found that the amount of money illusion exhibited by the vmPFC was correlated with the amount of money illusion exhibited in the evaluation of economic transactions. PMID:19307555

Integrated multienzyme electrochemical biosensors for monitoring malolactic fermentation in wines.

PubMed

Gamella, M; Campuzano, S; Conzuelo, F; Curiel, J A; Muñoz, R; Reviejo, A J; Pingarrón, José M

2010-05-15

Integrated amperometric biosensors for the determination of L-malic and L-lactic acids were developed by coimmobilization of the enzymes L-malate dehydrogenase (MDH) and diaphorase (DP), or L-lactate oxidase (LOX) and horseradish peroxidase (HRP), respectively, together with the redox mediator tetrathiafulvalene (TTF), on a 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM)-modified gold electrode by using a dialysis membrane. The electrochemical oxidation of TTF at +100mV (vs. Ag/AgCl), and the reduction of TTF(+) at -50mV were used for the monitoring of the enzyme reactions involved in L-malic and L-lactic acid determinations, respectively. Experimental variables concerning the biosensors composition and the detection conditions were optimized for each biosensor. Good relative standard deviation values were obtained in both cases for the measurements carried out with the same biosensor, with no need of cleaning or pretreatment of the bioelectrodes surface, and with different biosensors constructed in the same manner. After 7 days of continuous use, the MDH/DP biosensor still exhibited 90% of the original sensitivity, while the LOX/HRP biosensor yielded a 91% of the original response after 5 days. Calibration graphs for L-malic and L-lactic were obtained with linear ranges of 5.2x10(-7) to 2.0x10(-5) and 4.2x10(-7) to 2.0x10(-5)M, respectively. The calculated detection limits were 5.2x10(-7) and 4.2x10(-7)M, respectively. The biosensors exhibited a high selectivity with no significant interferences. They were applied to monitor malolactic fermentation (MLF) induced by inoculation of Lactobacillus plantarum CECT 748(T) into a synthetic wine. Samples collected during MLF were assayed for L-malic and L-lactic acids, and the results obtained with the biosensors exhibited a very good correlation when plotted against those obtained by using commercial enzymatic kits.

A Comparison of Cognitive Flexibility and Metalinguistic Skills in Adult Good and Poor Comprehenders

ERIC Educational Resources Information Center

Cartwright, Kelly B.; Bock, Allison M.; Coppage, Elizabeth A.; Hodgkiss, Melinda D.; Nelson, Marisa Isaac

2017-01-01

Good and poor comprehenders exhibit different profiles of cognitive abilities, despite comparable decoding skills. Recent work suggests that executive functions, particularly cognitive flexibility, may underlie poor comprehenders' difficulties in childhood and adulthood. However, metalinguistic skills that enable readers to reflect on various…

Hydrogen Gas Sensing Characteristics of Nanostructured NiO Thin Films Synthesized by SILAR Method

NASA Astrophysics Data System (ADS)

Karaduman, Irmak; Çorlu, Tugba; Yıldırım, M. Ali; Ateş, Aytunç; Acar, Selim

2017-07-01

Nanostructured NiO thin films have been synthesized by a facile, low-cost successive ionic layer adsorption and reaction (SILAR) method, and the effects of the film thickness on their hydrogen gas sensing properties investigated. The samples were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and energy-dispersive x-ray analysis. The XRD results revealed that the crystallinity improved with increasing thickness, exhibiting polycrystalline structure. SEM studies showed that all the films covered the glass substrate well. According to optical absorption measurements, the optical bandgap decreased with increasing film thickness. The gas sensing properties of the nanostructured NiO thin films were studied as a function of operating temperature and gas concentration. The samples showed good sensing performance of H2 gas with high response. The maximum response was 75% at operating temperature of 200°C for hydrogen gas concentration of 40 ppm. These results demonstrate that nanostructured NiO thin films synthesized by the SILAR method have potential for application in hydrogen detection.

Quasi-equilibrium theory for the distribution of rare alleles in a subdivided population: justification and implications.

PubMed

Burr, T L

2000-05-01

This paper examines a quasi-equilibrium theory of rare alleles for subdivided populations that follow an island-model version of the Wright-Fisher model of evolution. All mutations are assumed to create new alleles. We present four results: (1) conditions for the theory to apply are formally established using properties of the moments of the binomial distribution; (2) approximations currently in the literature can be replaced with exact results that are in better agreement with our simulations; (3) a modified maximum likelihood estimator of migration rate exhibits the same good performance on island-model data or on data simulated from the multinomial mixed with the Dirichlet distribution, and (4) a connection between the rare-allele method and the Ewens Sampling Formula for the infinite-allele mutation model is made. This introduces a new and simpler proof for the expected number of alleles implied by the Ewens Sampling Formula. Copyright 2000 Academic Press.

The good and bad of being fair: effects of procedural and interpersonal justice behaviors on regulatory resources.

PubMed

Johnson, Russell E; Lanaj, Klodiana; Barnes, Christopher M

2014-07-01

The justice literature has paid considerable attention to the beneficial effects of fair behaviors for recipients of such behaviors. It is possible, however, that exhibiting fair behaviors may come at a cost for actors. In this article, we integrate ego depletion theory with organizational justice research in order to examine the consequences of justice behaviors for actors. We used an experience-sampling method in a sample of managerial employees to examine the relations of performing procedural justice and interpersonal justice behaviors with subsequent changes in actors' regulatory resources. Our results indicate that procedural justice behaviors are draining, whereas interpersonal justice behaviors are replenishing for actors. Depletion, in turn, adversely affected the performance of citizenship behavior, and depletion mediated relations of justice behavior with citizenship. Furthermore, 2 traits that impact self-regulatory skills--extraversion and neuroticism--moderated the replenishing effects of engaging in interpersonal justice behaviors. We conclude by discussing implications and avenues for future research.

Optical constants of solid methane and ethane from 10,000 to 450/cm. [in outer planets atmospheres

NASA Technical Reports Server (NTRS)

Pearl, J.; Ngoh, M.; Ospina, M.; Khanna, R.

1991-01-01

Near- and mid-IR spectra of thin films of crystalling phase I and phase II C2H6 are presented using a combined least squares and Kramers-Kronig analysis. Complex refractive indices derived from these data are also presented. To obtain material in phase I, samples are annealed at 33 K for about 30 min; phase II is obtained by recooling below the transition temperature of 20.4 K. The derived optical parameters are shown. The infrared spectrum of phase I CH4 exhibits broad structureless absorptions at about 1300 and 2600/cm. On cooling the sample below 20.4 K (phase II), the absorptions are sharpened, and each band develops fine structure. The present results and those of Roux et al. (1979) are compared. The agreement with the real parts is found to be excellent; given the difference in resolution, the agreement with the imaginary parts is also good.

The HD molecule in small and medium cages of clathrate hydrates: Quantum dynamics studied by neutron scattering measurements and computation

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

Colognesi, Daniele; Celli, Milva; Ulivi, Lorenzo, E-mail: lorenzo.ulivi@isc.cnr.it

2014-10-07

We report inelastic neutron scattering (INS) measurements on molecular hydrogen deuteride (HD) trapped in binary cubic (sII) and hexagonal (sH) clathrate hydrates, performed at low temperature using two different neutron spectrometers in order to probe both energy and momentum transfer. The INS spectra of binary clathrate samples exhibit a rich structure containing sharp bands arising from both the rotational transitions and the rattling modes of the guest molecule. For the clathrates with sII structure, there is a very good agreement with the rigorous fully quantum simulations which account for the subtle effects of the anisotropy, angular and radial, of themore » host cage on the HD microscopic dynamics. The sH clathrate sample presents a much greater challenge, due to the uncertainties regarding the crystal structure, which is known only for similar crystals with different promoter, but nor for HD (or H{sub 2}) plus methyl tert-butyl ether (MTBE-d12)« less

Precarious employment in Chile: psychometric properties of the Chilean version of Employment Precariousness Scale in private sector workers.

PubMed

Vives-Vergara, Alejandra; González-López, Francisca; Solar, Orielle; Bernales-Baksai, Pamela; González, María José; Benach, Joan

2017-04-20

The purpose of this study is to perform a psychometric analysis (acceptability, reliability and factor structure) of the Chilean version of the new Employment Precariousness Scale (EPRES). The data is drawn from a sample of 4,248 private salaried workers with a formal contract from the first Chilean Employment Conditions, Work, Health and Quality of Life (ENETS) survey, applied to a nationally representative sample of the Chilean workforce in 2010. Item and scale-level statistics were performed to assess scaling properties, acceptability and reliability. The six-dimensional factor structure was examined with confirmatory factor analysis. The scale exhibited high acceptability (roughly 80%) and reliability (Cronbach's alpha 0.83) and the factor structure was confirmed. One subscale (rights) demonstrated poorer metric properties without compromising the overall scale. The Chilean version of the Employment Precariousness Scale (EPRES-Ch) demonstrated good metric properties, pointing to its suitability for use in epidemiologic and public health research.

Application of graphene oxide/lanthanum-modified carbon paste electrode for the selective determination of dopamine

NASA Astrophysics Data System (ADS)

Ye, Fengying; Feng, Chenqi; Fu, Ning; Wu, Huihui; Jiang, Jibo; Han, Sheng

2015-12-01

A home-made carbon paste electrode (CPE) was reformed by graphene oxide (GO)/lanthanum (La) complexes, and a modified electrode, called GO-La/CPE, was fabricated for the selective determination of dopamine (DA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several factors affecting the electrocatalytic performance of the modified sensor were investigated. Owning to the combination of GO and La ions, the GO-La/CPE sensor exhibited large surface area, well selectivity, good repeatability and stability in the oxidation reaction of DA. At optimal conditions, the response of the GO-La/CPE electrode for determining DA was linear in the region of 0.01-0.1 μM and 0.1-400.0 μM. The limit of detection was down to 0.32 nM (S/N = 3). In addition, this modified electrode was successfully applied to the detection of DA in real urine and serum samples by using standard adding method, showing its promising application in the electroanalysis of real samples.

Inhibition of Cholinesterases and Some Pro-Oxidant induced Oxidative Stress in Rats Brain by Two Tomato (Lycopersicon Esculentum) Varieties

PubMed Central

Oboh, G.; Bakare, O.O.; Ademosun, A.O.; Akinyemi, A.J.; Olasehinde, T.A.

2015-01-01

This study sought to investigate the effects of two tomato varieties [Lycopersicon esculentum Mill. var. esculentum (ESC) and Lycopersicon esculentum Mill. var. cerasiforme (CER)] on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities in vitro. Phenolics content, carotenoids characterisation, inhibition of Fe2+ and quinolinic acid-induced malondialdehyde (MDA) production in rats brain homogenate and NO* scavenging abilities were also assesed in addition to the AChE and BChE inhibition assays. There was no significant difference in the AChE inhibitory ability of the samples, while CER had significantly higher BChE inhibitory activity. Furthermore, the tomatoes inhibited Fe2+ and quinolinic acid-induced MDA production and further exhibited antioxidant activities through their NO* scavenging abilities. There was no significant difference in the phenolic content of the samples, while significantly high amounts of lycopene were detected in the tomatoes. The cholinesterase-inhibition and antioxidant properties of the “tomatoes” could make them good dietary means for the management of neurodegenerative disorders.

Comparing solvophobic and multivalent induced collapse in polyelectrolyte brushes

DOE PAGES

Jackson, Nicholas E.; Brettmann, Blair K.; Vishwanath, Venkatram; ...

2017-02-03

Here, coarse-grained molecular dynamics enhanced by free-energy sampling methods is used to examine the roles of solvophobicity and multivalent salts on polyelectrolyte brush collapse. Specifically, we demonstrate that while ostensibly similar, solvophobic collapsed brushes and multivalent-ion collapsed brushes exhibit distinct mechanistic and structural features. Notably, multivalent-induced heterogeneous brush collapse is observed under good solvent polymer backbone conditions, demonstrating that the mechanism of multivalent collapse is not contingent upon a solvophobic backbone. Umbrella sampling of the potential of mean-force (PMF) between two individual brush strands confirms this analysis, revealing starkly different PMFs under solvophobic and multivalent conditions, suggesting the role ofmore » multivalent “bridging” as the discriminating feature in trivalent collapse. Structurally, multivalent ions show a propensity for nucleating order within collapsed brushes, whereas poor-solvent collapsed brushes are more disordered; this difference is traced to the existence of a metastable PMF minimum for poor solvent conditions, and a global PMF minimum for trivalent systems, under experimentally relevant conditions.« less

Microwave plasma-assisted chemical vapor deposition of porous carbon film as supercapacitive electrodes

NASA Astrophysics Data System (ADS)

Wu, Ai-Min; Feng, Chen-Chen; Huang, Hao; Paredes Camacho, Ramon Alberto; Gao, Song; Lei, Ming-Kai; Cao, Guo-Zhong

2017-07-01

Highly porous carbon film (PCF) coated on nickel foam was prepared successfully by microwave plasma-assisted chemical vapor deposition (MPCVD) with C2H2 as carbon source and Ar as discharge gas. The PCF is uniform and dense with 3D-crosslinked nanoscale network structure possessing high degree of graphitization. When used as the electrode material in an electrochemical supercapacitor, the PCF samples verify their advantageous electrical conductivity, ion contact and electrochemical stability. The test results show that the sample prepared under 1000 W microwave power has good electrochemical performance. It displays the specific capacitance of 62.75 F/g at the current density of 2.0 A/g and retains 95% of its capacitance after 10,000 cycles at the current density of 2.0 A/g. Besides, its near-rectangular shape of the cyclic voltammograms (CV) curves exhibits typical character of an electric double-layer capacitor, which owns an enhanced ionic diffusion that can fit the requirements for energy storage applications.

Incorporation of flow injection analysis with dual-wavelength overlapping resonance Rayleigh scattering for rapid determination of malachite green and its metabolite in fish.

PubMed

Zhu, Jinghui; Qin, Mingyou; Liu, Shaopu; Liu, Zhongfang; Yang, Jidong; Hu, Xiaoli

2014-09-15

A flow injection analysis (FIA) system combined with dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) has been established and validated for rapid determination of malachite green (MG) and its metabolite in fish samples. Under experimental condition, MG would react with Erythrosin (Ery) to form ion-association complexes, resulting in the occurrence of two RRS peaks and a dramatic enhancement of RRS intensity. The maximum RRS peaks were located at 286 nm and 337 nm. It is noted that the increments of both of these two peaks were proportional to the concentration of MG. The detection limit of DWO-RRS was 1.5 ng/mL, which was comparable to several reported methods. Moreover, the results of real sample analysis exhibited an acceptable recovery between 97.5% and 103.6%, indicating that the method had good reproducibility. Copyright © 2014 Elsevier B.V. All rights reserved.

Analysis of the cross-reactivity of various 56 kDa recombinant protein antigens with serum samples collected after Orientia tsutsugamushi infection by ELISA.

PubMed

Chao, Chien-Chung; Huber, Erin S; Porter, Terrisita B; Zhang, Zhiwen; Ching, Wei-Mei

2011-06-01

Orientia tsutsugamushi, the etiologic agent of scrub typhus, has a highly expressed and immunodominant 56-kD outer membrane protein. This protein is one of the leading candidates for diagnosis and vaccine development for scrub typhus. Previous studies using recombinant 56-kD protein (r56s) derived from Karp strain (Kpr56) in a mouse model have shown good homologous protection but only moderate to poor heterologous protection. We evaluated the cross-reactivity of recombinant 56-kD proteins from Karp, Kato, Gilliam, TA763, and three chimeric 56-kD proteins. Not all r56s are equally reactive with strain-specific serum samples. These data provide a first glance of how reactive these r56s are toward the antiserum of different strains and which r56 exhibits the broadest reactivity. A formulation of this combination has the potential to provide broad protection against the heterologous challenge and to be used in a highly sensitive diagnostic assay.

Comparing solvophobic and multivalent induced collapse in polyelectrolyte brushes

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

Jackson, Nicholas E.; Brettmann, Blair K.; Vishwanath, Venkatram

Here, coarse-grained molecular dynamics enhanced by free-energy sampling methods is used to examine the roles of solvophobicity and multivalent salts on polyelectrolyte brush collapse. Specifically, we demonstrate that while ostensibly similar, solvophobic collapsed brushes and multivalent-ion collapsed brushes exhibit distinct mechanistic and structural features. Notably, multivalent-induced heterogeneous brush collapse is observed under good solvent polymer backbone conditions, demonstrating that the mechanism of multivalent collapse is not contingent upon a solvophobic backbone. Umbrella sampling of the potential of mean-force (PMF) between two individual brush strands confirms this analysis, revealing starkly different PMFs under solvophobic and multivalent conditions, suggesting the role ofmore » multivalent “bridging” as the discriminating feature in trivalent collapse. Structurally, multivalent ions show a propensity for nucleating order within collapsed brushes, whereas poor-solvent collapsed brushes are more disordered; this difference is traced to the existence of a metastable PMF minimum for poor solvent conditions, and a global PMF minimum for trivalent systems, under experimentally relevant conditions.« less

Investigating the origins of double photopeaks in CsI:Tl samples through activator mapping

NASA Astrophysics Data System (ADS)

Onken, Drew R.; Gridin, Sergii; Williams, Richard T.; Williams, Charles B.; Donati, George L.; Gayshan, Vadim; Vasyukov, Sergey; Gektin, Alex

2018-06-01

Careful examination of the origins of double photopeaks in CsI:Tl provides a foundation for exploring the relationship between activator homogeneity and photopeak resolution in scintillators. In rare cases, certain CsI:Tl crystals exhibit a second photopeak in the pulse-height spectrum. A combination of optical mapping and ICP-MS measurements reveals the presence of two distinct regions with differing Tl concentrations in these crystals. The oscillator strength of the 299 nm absorption A-band of Tl in CsI was measured to be 0.0526 ± 0.0008; this parameter can be used to quantify activator concentration from the optical absorption. Using published measurements of luminescence intensity versus Tl concentration, the distributions of Tl measured from optical absorption maps of the samples were reconstructed into photopeaks in good agreement with experiment. The distribution of Tl concentrations in these particular crystals allowed examining luminescence pulse shape as a function of Tl concentration.

Fabrication of conductive and high-dispersed Ppy@Ag/g-C3N4 composite photocatalysts for removing various pollutants in water

NASA Astrophysics Data System (ADS)

Zhu, Zhi; Tang, Xu; Ma, Changchang; Song, Minshan; Gao, Nailing; Wang, Youshan; Huo, Pengwei; Lu, Ziyang; Yan, Yongsheng

2016-11-01

The ternary conductive Ppy@Ag/g-C3N4 composite photocatalysts was successfully synthesized by polymerization process and surface polymerization technique. And the as-prepared Ppy@Ag/g-C3N4 sample exhibited the higher photocatalytic activity for various pollutant (MO, DM, TC, CIP, GFLX and EH) remove than that of pure g-C3N4 and Ag/g-C3N4 under visible light irradiation. It mainly originated from the Ag nanoparticles anchored between g-C3N4 and Ppy acted as electron transfer mediator that facilitated the charge carrier separation and then expending the lifetime of the carriers. Meanwhile, the obtained Ppy@Ag/g-C3N4 sample also showed a relatively good recycling stability which was the crucial factor for photocatalyst practical application. This work provided a new facile strategy for improving photo-degradation activity of g-C3N4 photocatalyst.

NGS tools for traceability in candies as high processed food products: Ion Torrent PGM versus conventional PCR-cloning.

PubMed

Muñoz-Colmenero, Marta; Martínez, Jose Luis; Roca, Agustín; Garcia-Vazquez, Eva

2017-01-01

The Next Generation Sequencing methodologies are considered the next step within DNA-based methods and their applicability in different fields is being evaluated. Here, we tested the usefulness of the Ion Torrent Personal Genome Machine (PGM) in food traceability analyzing candies as a model of high processed foods, and compared the results with those obtained by PCR-cloning-sequencing (PCR-CS). The majority of samples exhibited consistency between methodologies, yielding more information and species per product from the PGM platform than PCR-CS. Significantly higher AT-content in sequences of the same species was also obtained from PGM. This together with some taxonomical discrepancies between methodologies suggest that the PGM platform is still pre-mature for its use in food traceability of complex highly processed products. It could be a good option for analysis of less complex food, saving time and cost per sample. Copyright © 2016 Elsevier Ltd. All rights reserved.

One-step green synthesis of β-cyclodextrin/iron oxide-reduced graphene oxide nanocomposite with high supramolecular recognition capability: Application for vortex-assisted magnetic solid phase extraction of organochlorine pesticides residue from honey samples.

PubMed

Mahpishanian, Shokouh; Sereshti, Hassan

2017-02-17

In this research, β-cyclodextrin/iron oxide reduced graphene oxide hybrid nanostructure (β-CD/MRGO) with high water dispersability, excellent magnetic responsivity and molecular selectivity was prepared via a facile one step green strategy. The obtained nanomaterial was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and vibrating sample magnetometry (VSM), which confirmed the modification of GO with β-CD and magnetic nanoparticles. The formation mechanism of β-CD/MRGO was also discussed. The prepared magnetic nanocomposite was then applied as adsorbent in the vortex-assisted magnetic solid phase extraction (MSPE) of 16 organochlorine pesticides (OCPs) from honey samples prior to gas chromatography-electron capture detection (GC-ECD) analysis. Optimum extraction conditions have been assessed with respect to vortex time, sample pH, adsorbent amount, and salt concentration as well as desorption conditions (type and volume of desorption solvent and desorption time). A good level of linearity (2-10,000ngkg -1 ) with satisfactory determination coefficients (R 2 >0.9966) and suitable precision (%RSDs less than 7.8) was obtained for OCPs under the optimal conditions. The limits of detection and quantification of the method were obtained in the sub-parts per trillion (ppt) to parts per trillion range (LOD: 0.52-3.21ngkg -1 ; LOQ: 1.73-10.72ngkg -1 ) based on 3 and 10 signal to noise ratios, respectively. The MSPE method was successfully applied to analysis of OCPs in honey samples with recoveries in the range of 78.8% to 116.2% and RSDs (n=3) below 8.1%. The results demonstrated that β-CD/MRGO could exhibit good supramolecular recognition, enrichment capability and high extraction recoveries toward OCPs. Copyright © 2017 Elsevier B.V. All rights reserved.

Damage evolution analysis of coal samples under cyclic loading based on single-link cluster method

NASA Astrophysics Data System (ADS)

Zhang, Zhibo; Wang, Enyuan; Li, Nan; Li, Xuelong; Wang, Xiaoran; Li, Zhonghui

2018-05-01

In this paper, the acoustic emission (AE) response of coal samples under cyclic loading is measured. The results show that there is good positive relation between AE parameters and stress. The AE signal of coal samples under cyclic loading exhibits an obvious Kaiser Effect. The single-link cluster (SLC) method is applied to analyze the spatial evolution characteristics of AE events and the damage evolution process of coal samples. It is found that a subset scale of the SLC structure becomes smaller and smaller when the number of cyclic loading increases, and there is a negative linear relationship between the subset scale and the degree of damage. The spatial correlation length ξ of an SLC structure is calculated. The results show that ξ fluctuates around a certain value from the second cyclic loading process to the fifth cyclic loading process, but spatial correlation length ξ clearly increases in the sixth loading process. Based on the criterion of microcrack density, the coal sample failure process is the transformation from small-scale damage to large-scale damage, which is the reason for changes in the spatial correlation length. Through a systematic analysis, the SLC method is an effective method to research the damage evolution process of coal samples under cyclic loading, and will provide important reference values for studying coal bursts.

Development of Low Cost Soil Stabilization Using Recycled Material

NASA Astrophysics Data System (ADS)

Ahmad, F.; Yahaya, A. S.; Safari, A.

2016-07-01

Recycled tyres have been used in many geotechnical engineering projects such as soil improvement, soil erosion and slope stability. Recycled tyres mainly in chip and shredded form are highly compressible under low and normal pressures. This characteristic would cause challenging problems in some applications of soil stabilization such as retaining wall and river bank projects. For high tensile stress and low tensile strain the use of fiberglass would be a good alternative for recycled tyre in some cases. To evaluate fiberglass as an alternative for recycled tyre, this paper focused on tests of tensile tests which have been carried out between fiberglass and recycled tyre strips. Fibreglass samples were produced from chopped strand fibre mat, a very low-cost type of fibreglass, which is cured by resin and hardener. Fibreglass samples in the thickness of 1 mm, 2 mm, 3 mm and 4 mm were developed 100 mm x 300 mm pieces. It was found that 3 mm fibreglass exhibited the maximum tensile load (MTL) and maximum tensile stress (MTS) greater than other samples. Statistical analysis on 3 mm fibreglass indicated that in the approximately equal MTL fibreglass samples experienced 2% while tyre samples experienced 33.9% ultimate tensile strain (UTST) respectively. The results also showed an approximately linear relationship between stress and strain for fibreglass samples and Young's modulus (E), ranging from 3581 MPa to 4728 MPa.

Development of dopant-free conductive bioelastomers

PubMed Central

Xu, Cancan; Huang, Yihui; Yepez, Gerardo; Wei, Zi; Liu, Fuqiang; Bugarin, Alejandro; Tang, Liping; Hong, Yi

2016-01-01

Conductive biodegradable materials are of great interest for various biomedical applications, such as tissue repair and bioelectronics. They generally consist of multiple components, including biodegradable polymer/non-degradable conductive polymer/dopant, biodegradable conductive polymer/dopant or biodegradable polymer/non-degradable inorganic additives. The dopants or additives induce material instability that can be complex and possibly toxic. Material softness and elasticity are also highly expected for soft tissue repair and soft electronics. To address these concerns, we designed a unicomponent dopant-free conductive polyurethane elastomer (DCPU) by chemically linking biodegradable segments, conductive segments, and dopant molecules into one polymer chain. The DCPU films which had robust mechanical properties with high elasticity and conductivity can be degraded enzymatically and by hydrolysis. It exhibited great electrical stability in physiological environment with charge. Mouse 3T3 fibroblasts survived and proliferated on these films exhibiting good cytocompatibility. Polymer degradation products were non-toxic. DCPU could also be processed into a porous scaffold and in an in vivo subcutaneous implantation model, exhibited good tissue compatibility with extensive cell infiltration over 2 weeks. Such biodegradable DCPU with good flexibility and elasticity, processability, and electrical stability may find broad applications for tissue repair and soft/stretchable/wearable bioelectronics. PMID:27686216

Dermal Fibroblasts from Different Layers of Pig Skin Exhibit Different Profibrotic and Morphological Characteristics.

PubMed

Zuo, Yanhai; Yu, Xiaoping; Lu, Shuliang

2016-11-01

In vitro studies of human dermal fibroblast (DF) heterogeneity have long been reported, yet in vivo studies and related research on animals are rare. The objectives of the study were to determine whether the DFs of pigs exhibit heterogeneity and to identify an animal model for the in vivo study of DF heterogeneity. The skin of three female red Duroc pigs (FRDPs) was separated into six layers, and the second and fifth layers (i.e., the superficial and deep dermis) were used in the establishment of wound models and cell cultures. To create the wound models, 54 tongue-shaped flaps were created on one side of the dorsum, and the underlying dermis was then fully replaced with the superficial or deep dermis (the superficial and deep groups, respectively). Skin samples were harvested at postoperative weeks 1, 2, and 3 for measurements of the normal and wounded skin thicknesses. Cells cultured from the superficial and deep dermis (i.e., superficial and deep DFs) were subjected to quantitative estimation of collagen and electron microscopy. The wounded skin thickness in the deep group was significantly greater than that in the superficial group. In contrast with the long deep DFs, the superficial DFs were short and exhibited microvilli-like cell surface projections. Compared with the superficial DFs, the deep DFs exhibited a greater density of rough endoplasmic reticulum and produced significantly more collagen. Similar to humans, FRDPs exhibit DF heterogeneity and should thus be a good animal model for in vivo studies of DF heterogeneity. Anat Rec, 299:1585-1599, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Sample integrity evaluation and EPA method 325B interlaboratory comparison for select volatile organic compounds collected diffusively on Carbopack X sorbent tubes

NASA Astrophysics Data System (ADS)

Oliver, Karen D.; Cousett, Tamira A.; Whitaker, Donald A.; Smith, Luther A.; Mukerjee, Shaibal; Stallings, Casson; Thoma, Eben D.; Alston, Lillian; Colon, Maribel; Wu, Tai; Henkle, Stacy

2017-08-01

A sample integrity evaluation and an interlaboratory comparison were conducted in application of U.S. Environmental Protection Agency (EPA) Methods 325A and 325B for diffusively monitoring benzene and other selected volatile organic compounds (VOCs) using Carbopack X sorbent tubes. To evaluate sample integrity, VOC samples were refrigerated for up to 240 days and analyzed using thermal desorption/gas chromatography-mass spectrometry at the EPA Office of Research and Development laboratory in Research Triangle Park, NC, USA. For the interlaboratory comparison, three commercial analytical laboratories were asked to follow Method 325B when analyzing samples of VOCs that were collected in field and laboratory settings for EPA studies. Overall results indicate that the selected VOCs collected diffusively on sorbent tubes generally were stable for 6 months or longer when samples were refrigerated. This suggests the specified maximum 30-day storage time of VOCs collected diffusively on Carbopack X passive samplers and analyzed using Method 325B might be able to be relaxed. Interlaboratory comparison results were in agreement for the challenge samples collected diffusively in an exposure chamber in the laboratory, with most measurements within ±25% of the theoretical concentration. Statistically significant differences among laboratories for ambient challenge samples were small, less than 1 part per billion by volume (ppbv). Results from all laboratories exhibited good precision and generally agreed well with each other.

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

PubMed

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

2017-05-15

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

Web-Based Student Art Galleries

ERIC Educational Resources Information Center

Burton, David

2010-01-01

Exhibition is an important part of the artistic process for students as well as professional artists, but finding enough good places to exhibit can be as difficult for student artists as for adult artists. Venues that are accessible, display art attractively, and provide adequate space for many artists are usually in short supply. There is an…

Physico-chemical characterisation of different clindamycin phosphate samples.

PubMed

Vranić, Edina; Planinsek, Odon; Tivadar, Andrijana; Hadzović, Sabira; Srcic, Stanko

2007-05-01

For the majority of the pharmaceutical dosage forms, the substances that are used maintain solid state under the standard storage conditions, i.e. powders. The interactions of pharmaceutical powders (active ingredient(s) and excipients) with liquids and vapors (particularly aqueous solutions and their vapors) occur almost always during the production process. From the physical point of view, the interactions among individual components may differ from the expected because chemically identical substances obtained from different producers vary very much. These differences influence either the production process and/or the pharmaceutical form properties. In order to overcome these problems it is necessary to establish a control over the physico-chemical properties of the used materials. The aim of this work was to determine physico-chemical properties of three powder clindamycin phosphate samples (labeled as sample S(1), S(2) and S(3)) acquired through different suppliers. All the analysis were made for the purpose of establishing possible differences among the tested samples that showed variable physical stability in the solution: recrystallization of the S(3) sample in the aqueous solution has been established during storage under standard conditions. On the basis of the obtained data it was possible to recognize the differences among the tested clindamycin phosphate samples and to explain the anomalous behavior of one sample. The surface free energy components for the investigated clindamycin phosphate samples were determined using Wu and Good- van Oss method. The investigated clindamycin phosphate samples exhibit certain differences in surface free energy values as well as in surface morphology and thermal behavior. Comparison of alpha + and alpha - values leads to the conclusion that all three clindamycin phosphate samples perform as monopolar, more electron acceptors, i.e. Lewis acids. However, an important difference exists between samples S(1) and S(2) on one and S(3) on the other side. Sample S(3) exhibits stronger acidic behavior, what could be connected with its recrystallization during the storage. The samples S(1), S(2) and S(3) have different melting points e.g. "onset" temperatures. When the melting points move towards 200 (o ) C, the width of the "onset" temperature peak is especially important. In the case of wider peak, the potential for recrystallization seems to be higher. According to the stated, the sample S1 would be the "sample of choice" for the formulation of the stable pharmaceutical dosage form and has not shown any recrystallization tendencies during the storage period.

Voids and constraints on nonlinear clustering of galaxies

NASA Technical Reports Server (NTRS)

Vogeley, Michael S.; Geller, Margaret J.; Park, Changbom; Huchra, John P.

1994-01-01

Void statistics of the galaxy distribution in the Center for Astrophysics Redshift Survey provide strong constraints on galaxy clustering in the nonlinear regime, i.e., on scales R equal to or less than 10/h Mpc. Computation of high-order moments of the galaxy distribution requires a sample that (1) densely traces the large-scale structure and (2) covers sufficient volume to obtain good statistics. The CfA redshift survey densely samples structure on scales equal to or less than 10/h Mpc and has sufficient depth and angular coverage to approach a fair sample on these scales. In the nonlinear regime, the void probability function (VPF) for CfA samples exhibits apparent agreement with hierarchical scaling (such scaling implies that the N-point correlation functions for N greater than 2 depend only on pairwise products of the two-point function xi(r)) However, simulations of cosmological models show that this scaling in redshift space does not necessarily imply such scaling in real space, even in the nonlinear regime; peculiar velocities cause distortions which can yield erroneous agreement with hierarchical scaling. The underdensity probability measures the frequency of 'voids' with density rho less than 0.2 -/rho. This statistic reveals a paucity of very bright galaxies (L greater than L asterisk) in the 'voids.' Underdensities are equal to or greater than 2 sigma more frequent in bright galaxy samples than in samples that include fainter galaxies. Comparison of void statistics of CfA samples with simulations of a range of cosmological models favors models with Gaussian primordial fluctuations and Cold Dark Matter (CDM)-like initial power spectra. Biased models tend to produce voids that are too empty. We also compare these data with three specific models of the Cold Dark Matter cosmogony: an unbiased, open universe CDM model (omega = 0.4, h = 0.5) provides a good match to the VPF of the CfA samples. Biasing of the galaxy distribution in the 'standard' CDM model (omega = 1, b = 1.5; see below for definitions) and nonzero cosmological constant CDM model (omega = 0.4, h = 0.6 lambda(sub 0) = 0.6, b = 1.3) produce voids that are too empty. All three simulations match the observed VPF and underdensity probability for samples of very bright (M less than M asterisk = -19.2) galaxies, but produce voids that are too empty when compared with samples that include fainter galaxies.

Spectral, thermal, XRD and SEM studies of charge-transfer complexation of hexamethylenediamine and three types of acceptors: π-, σ- and vacant orbital acceptors that include quinol, picric acid, bromine, iodine, SnCl4 and ZnCl2 acceptors

NASA Astrophysics Data System (ADS)

Adam, Abdel Majid A.; Refat, Moamen S.; Saad, Hosam A.

2013-11-01

In this work, structural, thermal, morphological and pharmacological characterization was performed on the interactions between a hexamethylenediamine (HMDA) donor and three types of acceptors to understand the complexation behavior of diamines. The three types of acceptors include π-acceptors (i.e., quinol (QL) and picric acid (PA)), σ-acceptors (i.e., bromine and iodine) and vacant orbital acceptors (i.e., tin(IV) tetrachloride (SnCl4) and zinc chloride (ZnCl2)). The characterization of the obtained CT complexes was performed using elemental analysis, infrared (IR), Raman, 1H NMR and electronic absorption spectroscopy, powder X-ray diffraction (XRD) and thermogravimetric (TG) analysis. Their morphologies were studied using scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). The biological activities of the obtained CT complexes were tested for their antibacterial activities. The complex containing the QL acceptor exhibited a remarkable electronic spectrum with a strong, broad absorption band, which had an observed λmax that was at a much longer wavelength than those of the free reactants. In addition, this complex exhibited strong antimicrobial activities against various bacterial and fungal strains compared to standard drugs. The complexes containing the PA, iodine, Sn(IV) and Zn(II) acceptors exhibited good thermal stability up to 240, 330, 275 and 295 °C, respectively. The complexes containing bromine, Sn(IV) and Zn(II) acceptors exhibited good crystallinity. In addition to its good crystallinity properties, the complex containing the bromine acceptor exhibits a remarkable morphology feature.

In situ high temperature X-Ray diffraction study of the phase equilibria in the UO2-PuO2-Pu2O3 system

NASA Astrophysics Data System (ADS)

Belin, Renaud C.; Strach, Michal; Truphémus, Thibaut; Guéneau, Christine; Richaud, Jean-Christophe; Rogez, Jacques

2015-10-01

The region of the U-Pu-O phase diagram delimited by the compounds UO2-PuO2-Pu2O3 is known to exhibit a miscibility gap at low temperature. Consequently, MOX fuels with a composition entering this region could decompose into two fluorite phases and thus exhibit chemical heterogeneities. The experimental data on this domain found in the literature are scarce and usually provided using DTA that is not suitable for the investigation of such decomposition phenomena. In the present work, new experimental data, i.e. crystallographic phases, lattice parameters, phase fractions and temperature of phase separation, were measured in the composition range 0.14 < Pu/(U + Pu) < 0.62 and 1.85 < O/(U + Pu) < 2 from 298 to 1750 K using a novel in situ high temperature X-ray diffraction apparatus. A very good agreement is found between the temperature of phase separation determined from our results and using the thermodynamic model of the U-Pu-O system based on the CALPHAD method. Also, the combined use of thermodynamic calculations and XRD results refinement proved helpful in the determination of the O/M ratio of the samples during cooling. The methodology used in the current work might be useful to investigate other oxides systems exhibiting a miscibility gap.

Plasmonic Enzyme-Linked Immunosorbent Assay Using Nanospherical Brushes as a Catalase Container for Colorimetric Detection of Ultralow Concentrations of Listeria monocytogenes.

PubMed

Chen, Rui; Huang, Xiaolin; Xu, Hengyi; Xiong, Yonghua; Li, Yanbin

2015-12-30

Plasmonic enzyme-linked immunosorbent assay (pELISA) based on catalase (CAT)-mediated gold nanoparticle growth exhibits ultrahigh sensitivity for detecting disease-related biomarkers using sandwich formats. However, the limit of detection (LOD) of this strategy for Listeria monocytogenes is only around 10(3) CFU/mL, which considerably exceeds the amount of L. monocytogenes commonly present in food products (<100 CFU/g). Herein, we report an improved pELISA method for detection of L. monocytogenes at ultralow concentrations with the sandwich formats using silica nanoparticles carrying poly(acrylic acid) brushes as a "CAT container" to increase enzyme loading for enhancing the detection signal. Under optimal conditions, the proposed pELISA exhibits good specificity and excellent sensitivity for L. monocytogenes with a LOD of 8 × 10(1) CFU/mL in 0.01 M phosphate-buffered saline, via a reaction that can be discriminated by the naked eye. The LOD obtained by this method was 2 and 5 orders of magnitude lower than that of conventional CAT-based pELISA and horseradish peroxidase (HRP)-based conventional ELISA, respectively. Coupled with large-volume immunomagnetic separation, the LOD for L. monocytogenes-spiked lettuce samples reached 8 × 10(1) CFU/g. The improved pELISA also exhibited a great potential in detecting a single cell of L. monocytogenes in 100 μL of solution.

Kinetic analysis of the non-isothermal crystallization process, magnetic and mechanical properties of FeCoBSiNb and FeCoBSiNbCu bulk metallic glasses

NASA Astrophysics Data System (ADS)

Ramasamy, Parthiban; Stoica, Mihai; Taghvaei, A. H.; Prashanth, K. G.; Ravi Kumar, Eckert, Jürgen

2016-02-01

The crystallization kinetics of [(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4 and {[(Fe0.5Co0.5)0.75B0.2Si0.05]0.96Nb0.04}99.5Cu0.5 bulk metallic glasses were evaluated using differential scanning calorimetry under non-isothermal condition. The fully glassy rods with diameters up to 2 mm were obtained by copper mold injection casting. Both glasses show good thermal stability, but the addition of only 0.5% Cu completely changes the crystallization behavior. The average activation energy required for crystallization decreases from 645 kJ/mol to 425 kJ/mol after Cu addition. Upon heating, the Cu-free alloy forms only the metastable Fe23B6 phase. In contrast, two well-separated exothermic events are observed for the Cu-added bulk glassy samples. First, the (Fe,Co) phase nucleates and then (Fe,Co)2B and/or (Fe,Co)3B crystallize from the remaining glassy matrix. The Cu-added alloy exhibits a lower coercivity and a higher magnetic saturation than the base alloy, both in as-cast as well as in annealed condition. Besides, the Cu-added glassy sample with 2 mm diameter exhibits a maximum compressive fracture strength of 3913 MPa together with a plastic strain of 0.6%, which is highest plastic strain ever reported for 2 mm diameter ferromagnetic bulk metallic glass sample. Although Cu addition improves the magnetic and mechanical properties of the glass, it affects the glass-forming ability of the base alloy.

Highly sensitive strategy for Hg2+ detection in environmental water samples using long lifetime fluorescence quantum dots and gold nanoparticles.

PubMed

Huang, Dawei; Niu, Chenggang; Ruan, Min; Wang, Xiaoyu; Zeng, Guangming; Deng, Canhui

2013-05-07

The authors herein described a time-gated fluorescence resonance energy transfer (TGFRET) sensing strategy employing water-soluble long lifetime fluorescence quantum dots and gold nanoparticles to detect trace Hg(2+) ions in aqueous solution. The water-soluble long lifetime fluorescence quantum dots and gold nanoparticles were functionalized by two complementary ssDNA, except for four deliberately designed T-T mismatches. The quantum dot acted as the energy-transfer donor, and the gold nanoparticle acted as the energy-transfer acceptor. When Hg(2+) ions were present in the aqueous solution, DNA hybridization will occur because of the formation of T-Hg(2+)-T complexes. As a result, the quantum dots and gold nanoparticles are brought into close proximity, which made the energy transfer occur from quantum dots to gold nanoparticles, leading to the fluorescence intensity of quantum dots to decrease obviously. The decrement fluorescence intensity is proportional to the concentration of Hg(2+) ions. Under the optimum conditions, the sensing system exhibits the same liner range from 1 × 10(-9) to 1 × 10(-8) M for Hg(2+) ions, with the detection limits of 0.49 nM in buffer and 0.87 nM in tap water samples. This sensor was also used to detect Hg(2+) ions from samples of tap water, river water, and lake water spiked with Hg(2+) ions, and the results showed good agreement with the found values determined by an atomic fluorescence spectrometer. In comparison to some reported colorimetric and fluorescent sensors, the proposed method displays the advantage of higher sensitivity. The TGFRET sensor also exhibits excellent selectivity and can provide promising potential for Hg(2+) ion detection.

Rapid automated method for on-site determination of sulfadiazine in fish farming: a stainless steel veterinary syringe coated with a selective membrane of PVC serving as a potentiometric detector in a flow-injection-analysis system.

PubMed

Almeida, S A A; Amorim, L R; Heitor, A H; Montenegro, M C B S M; Barbosa, J; Sá, L C; Sales, M G F

2011-12-01

Sulfadiazine is an antibiotic of the sulfonamide group and is used as a veterinary drug in fish farming. Monitoring it in the tanks is fundamental to control the applied doses and avoid environmental dissemination. Pursuing this goal, we included a novel potentiometric design in a flow-injection assembly. The electrode body was a stainless steel needle veterinary syringe of 0.8-mm inner diameter. A selective membrane of PVC acted as a sensory surface. Its composition, the length of the electrode, and other flow variables were optimized. The best performance was obtained for sensors of 1.5-cm length and a membrane composition of 33% PVC, 66% o-nitrophenyloctyl ether, 1% ion exchanger, and a small amount of a cationic additive. It exhibited Nernstian slopes of 61.0 mV decade(-1) down to 1.0 × 10(-5) mol L(-1), with a limit of detection of 3.1 × 10(-6) mol L(-1) in flowing media. All necessary pH/ionic strength adjustments were performed online by merging the sample plug with a buffer carrier of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, pH 4.9. The sensor exhibited the advantages of a fast response time (less than 15 s), long operational lifetime (60 days), and good selectivity for chloride, nitrite, acetate, tartrate, citrate, and ascorbate. The flow setup was successfully applied to the analysis of aquaculture waters. The analytical results were validated against those obtained with liquid chromatography-tandem mass spectrometry procedures. The sampling rate was about 84 samples per hour and recoveries ranged from 95.9 to 106.9%.

Clinical characteristics of a sample of patients with cat eye syndrome.

PubMed

Rosa, Rafael Fabiano Machado; Mombach, Rômulo; Zen, Paulo Ricardo Gazzola; Graziadio, Carla; Paskulin, Giorgio Adriano

2010-01-01

Cat eye syndrome is considered a rare chromosome disease with a highly variable phenotype. The objective of this paper was to describe the clinical characteristics of a sample of patients with cat eye syndrome who were seen at our service. This is a retrospective analysis of a sample of six patients with diagnoses of cat eye syndrome. All of these patients’ karyotypes exhibited the presence of an additional marker chromosome, inv dup(22)(pter->q11.2::q11.2->pter). One patient also exhibited mosaicism with a lineage that had a normal chromosomal constitution. Clinical and follow-up data were collected from the patients’ medical records. Fisher’s exact test was used to compare the frequencies observed in our study with figures given in the literature (P<0.05). The main abnormalities observed were preauricular tags and/or pits and anal atresia (both observed in 83% of cases). Coloboma of the iris, an important finding with this syndrome, was observed in two cases (33%). Congenital heart disease was detected in four patients (67%) and the main defect found was interatrial communication (75%). Uncommon findings included hemifacial microsomia combined with unilateral microtia and biliary atresia. Just one of these patients died, from chylothorax and sepsis. The phenotype observed in cat eye syndrome is highly variable and may be superimposed on the phenotype of the oculo-auriculo-vertebral spectrum. Although these patients usually have good prognosis, including from a neurological point of view, we believe that all patients with the syndrome should be assessed very early on for the presence of cardiac, biliary and anorectal malformations, which may avoid possible complications in the future, including patient deaths.

Mechanical properties and in vitro bioactivity of Ca5(PO4)2SiO4 bioceramic.

PubMed

Lu, Wenhao; Duan, Wei; Guo, Yaping; Ning, Congqin

2012-02-01

Pure Ca(5)(PO(4))(2)SiO(4) bioceramic was first prepared by a sol-gel method using triethyl phosphate, tetraethoxysilane, and calcium nitrate tetrahydrate as original materials. Simulated body fluid (SBF) immersion tests revealed that Ca(5)(PO(4))(2)SiO(4) samples had a greater in vitro apatite-forming ability than hydroxyapatite (HA). After soaking Ca(5)(PO(4))(2)SiO(4) samples in the SBF for 1 day, bone-like apatite precipitated on the surfaces and the apatite layer became thicker with increasing the soaking time. However, few bone-like apatites precipitated on the HA samples even after soaking in the SBF for 7 days. The good in vitro bioactivity of Ca(5)(PO(4))(2)SiO(4) samples was attributed to the silanol (Si-OH) groups and greater solubility of Ca(5)(PO(4))(2)SiO(4). In addition, hot-pressed Ca(5)(PO(4))(2)SiO(4) ceramic exhibited lower bending strength and elastic modulus than hot-pressed HA, since the former had a lower relative density than the latter. The results have shown that Ca(5)(PO(4))(2)SiO(4) is a potential candidate material for bone repair. © The Author(s), 2010.

Ultra-facile fabrication of phosphorus doped egg-like hierarchic porous carbon with superior supercapacitance performance by microwave irradiation combining with self-activation strategy

NASA Astrophysics Data System (ADS)

Zhang, Deyi; Han, Mei; Li, Yubing; He, Jingjing; Wang, Bing; Wang, Kunjie; Feng, Huixia

2017-12-01

Herein, we report an ultra-facile fabrication method for a phosphorus doped egg-like hierarchic porous carbon by microwave irradiation combining with self-activation strategy under air atmosphere. Comparing with the traditional pyrolytic carbonization method, the reported method exhibits incomparable merits, such as high energy efficiency, ultra-fast and inert atmosphere protection absent fabrication process. Similar morphology and graphitization degree with the sample fabricated by the traditional pyrolytic carbonization method under inert atmosphere protection for 2 h can be easily achieved by the reported microwave irradiation method just for 3 min under ambient atmosphere. The samples fabricated by the reported method display a unique phosphorus doped egg-like hierarchic porous structure, high specific surface area (1642 m2 g-1) and large pore volume (2.04 cm3 g-1). Specific capacitance of the samples fabricated by the reported method reaches up to 209 F g-1, and over 96.2% of initial capacitance remains as current density increasing from 0.5 to 20 A g-1, indicating the superior capacitance performance of the fabricated samples. The hierarchic porous structure, opened microporosity, additional pseudocapacitance, high electrolyte-accessible surface area and good conductivity make essential contribution to its superior capacitance performance.

Measuring Blood Glucose Concentrations in Photometric Glucometers Requiring Very Small Sample Volumes.

PubMed

Demitri, Nevine; Zoubir, Abdelhak M

2017-01-01

Glucometers present an important self-monitoring tool for diabetes patients and, therefore, must exhibit high accuracy as well as good usability features. Based on an invasive photometric measurement principle that drastically reduces the volume of the blood sample needed from the patient, we present a framework that is capable of dealing with small blood samples, while maintaining the required accuracy. The framework consists of two major parts: 1) image segmentation; and 2) convergence detection. Step 1 is based on iterative mode-seeking methods to estimate the intensity value of the region of interest. We present several variations of these methods and give theoretical proofs of their convergence. Our approach is able to deal with changes in the number and position of clusters without any prior knowledge. Furthermore, we propose a method based on sparse approximation to decrease the computational load, while maintaining accuracy. Step 2 is achieved by employing temporal tracking and prediction, herewith decreasing the measurement time, and, thus, improving usability. Our framework is tested on several real datasets with different characteristics. We show that we are able to estimate the underlying glucose concentration from much smaller blood samples than is currently state of the art with sufficient accuracy according to the most recent ISO standards and reduce measurement time significantly compared to state-of-the-art methods.

Aquarius L-Band Microwave Radiometer: Three Years of Radiometric Performance and Systematic Effects

NASA Technical Reports Server (NTRS)

Piepmeier, Jeffrey R.; Hong, Liang; Pellerano, Fernando A.

2015-01-01

The Aquarius L-band microwave radiometer is a three-beam pushbroom instrument designed to measure sea surface salinity. Results are analyzed for performance and systematic effects over three years of operation. The thermal control system maintains tight temperature stability promoting good gain stability. The gain spectrum exhibits expected orbital variations with 1f noise appearing at longer time periods. The on-board detection and integration scheme coupled with the calibration algorithm produce antenna temperatures with NEDT 0.16 K for 1.44-s samples. Nonlinearity is characterized before launch and the derived correction is verified with cold-sky calibration data. Finally, long-term drift is discovered in all channels with 1-K amplitude and 100-day time constant. Nonetheless, it is adeptly corrected using an exponential model.

Investigation of novel zinc molybdate-graphene nanocomposite for supercapacitor applications

NASA Astrophysics Data System (ADS)

Reddy, B. Joji; Vickraman, P.; Justin, A. Simon

2018-06-01

Novel zinc molybdate-graphene nanocomposite is prepared for the first time in a fast, facile and eco-friendly microwave synthesis route as an electrode material for electrochemical supercapacitors. The as-prepared sample is investigated by X-ray diffraction, FTIR, Raman, scanning electron microscope and transmission electron microscope techniques. The studies have confirmed the formation of ZnMoO4 and its composite with graphene. The synthesized materials are subjected to electrochemical characterization studies in 2M KOH electrolyte solution which prove that ZnMoO4-graphene as an effective electrode material for supercapacitor applications. ZnMoO4 in its composite behavior has exhibited a specific capacitance of 272.93 F g- 1 at 0.5 A g- 1 with good cyclic stability for 1000 cycles.

Single-walled carbon nanotube/metalloporphyrin composites for the chemiresistive detection of amines and meat spoilage.

PubMed

Liu, Sophie F; Petty, Alexander R; Sazama, Graham T; Swager, Timothy M

2015-05-26

Chemiresistive detectors for amine vapors were made from single-walled carbon nanotubes by noncovalent modification with cobalt meso-arylporphyrin complexes. We show that through changes in the oxidation state of the metal, the electron-withdrawing character of the porphyrinato ligand, and the counteranion, the magnitude of the chemiresistive response to ammonia could be improved. The devices exhibited sub-ppm sensitivity and high selectivity toward amines as well as good stability to air, moisture, and time. The application of these chemiresistors in the detection of various biogenic amines (i.e. putrescine, cadaverine) and in the monitoring of spoilage in raw meat and fish samples (chicken, pork, salmon, cod) over several days was also demonstrated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Uncertainty in least-squares fits to the thermal noise spectra of nanomechanical resonators with applications to the atomic force microscope.

PubMed

Sader, John E; Yousefi, Morteza; Friend, James R

2014-02-01

Thermal noise spectra of nanomechanical resonators are used widely to characterize their physical properties. These spectra typically exhibit a Lorentzian response, with additional white noise due to extraneous processes. Least-squares fits of these measurements enable extraction of key parameters of the resonator, including its resonant frequency, quality factor, and stiffness. Here, we present general formulas for the uncertainties in these fit parameters due to sampling noise inherent in all thermal noise spectra. Good agreement with Monte Carlo simulation of synthetic data and measurements of an Atomic Force Microscope (AFM) cantilever is demonstrated. These formulas enable robust interpretation of thermal noise spectra measurements commonly performed in the AFM and adaptive control of fitting procedures with specified tolerances.

Uncertainty in least-squares fits to the thermal noise spectra of nanomechanical resonators with applications to the atomic force microscope

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

Sader, John E., E-mail: jsader@unimelb.edu.au; Yousefi, Morteza; Friend, James R.

2014-02-15

Thermal noise spectra of nanomechanical resonators are used widely to characterize their physical properties. These spectra typically exhibit a Lorentzian response, with additional white noise due to extraneous processes. Least-squares fits of these measurements enable extraction of key parameters of the resonator, including its resonant frequency, quality factor, and stiffness. Here, we present general formulas for the uncertainties in these fit parameters due to sampling noise inherent in all thermal noise spectra. Good agreement with Monte Carlo simulation of synthetic data and measurements of an Atomic Force Microscope (AFM) cantilever is demonstrated. These formulas enable robust interpretation of thermal noisemore » spectra measurements commonly performed in the AFM and adaptive control of fitting procedures with specified tolerances.« less

Tests for senescent decline in annual survival probabilities of common pochards, Aythya ferina

USGS Publications Warehouse

Nichols, J.D.; Hines, J.E.; Blums, P.

1997-01-01

Senescent decline in survival probabilities of animals is a topic about which much has been written but little is known. Here, we present formal tests of senescence hypotheses, using 1373 recaptures from 8877 duckling (age 0) and 504 yearling Common Pochards (Aythya ferina) banded at a Latvian study site, 1975-1992. The tests are based on capture-recapture models that explicitly incorporate sampling probabilities that, themselves, may exhibit timeand age-specific variation. The tests provided no evidence of senescent decline in survival probabilities for this species. Power of the most useful test was low for gradual declines in annual survival probability with age, but good for steeper declines. We recommend use of this type of capture-recapture modeling and analysis for other investigations of senescence in animal survival rates.

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.

Probiotic Properties of Lactobacillus fermentum Strains Isolated from Human Oral Samples and Description of their Antibacterial Activity.

PubMed

Fuochi, Virginia; Volti, Giovanni Li; Furneri, Pio M

2017-01-01

Gram positive bacteria produce peptides, defined bacteriocins which exhibit good antibacterial activity. We evaluated the ability of L. fermentum to produce bacteriocins having therefore, good probiotic features and finally, be safe towards microglial cells. Eight wild strains, identified using molecular techniques, were investigated for the evaluation of resistance to bile salts, low pH, H2O2 production, biofilm formation, antibacterial activity and safety on microglia cells (BV2). The determination of the susceptibility/resistance profile showed that the strains are sensitive to the antibiotics tested. All strains showed a good tolerability to extremely low pH as well as resisting in presence of bile salts. In addition, the strains showed excellent activity against pathogens and one of them (LAC 42) showed activity also against Pseudomonas aeruginosa and Klebsiella pneumoniae. Finally, LAC 42 and its active compound did not change microglia cell viability following 24h exposure. Our data on this antibacterial molecule suggest that it is a compound with low molecular weight and with highly hydrophilic component. These results describe the characteristics of Lactobacillus strains and provide evidences for their possible use as new potential probiotic. In addition, other studies are now warranted to exploit the antibacterial activity of the supernatant LAC 42 and for its complete chemical characterization. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Non-destructive profiling of volatile organic compounds using HS-SPME/GC-MS and its application for the geographical discrimination of white rice.

PubMed

Lim, Dong Kyu; Mo, Changyeun; Lee, Dong-Kyu; Long, Nguyen Phuoc; Lim, Jongguk; Kwon, Sung Won

2018-01-01

The authenticity determination of white rice is crucial to prevent deceptive origin labeling and dishonest trading. However, a non-destructive and comprehensive method for rapidly discriminating the geographical origins of white rice between countries is still lacking. In the current study, we developed a volatile organic compound based geographical discrimination method using headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS) to discriminate rice samples from Korea and China. A partial least squares discriminant analysis (PLS-DA) model exhibited a good classification of white rice between Korea and China (accuracy = 0.958, goodness of fit = 0.937, goodness of prediction = 0.831, and permutation test p-value = 0.043). Combining the PLS-DA based feature selection with the differentially expressed features from the unpaired t-test and significance analysis of microarrays, 12 discriminatory biomarkers were found. Among them, hexanal and 1-hexanol have been previously known to be associated with the cultivation environment and storage conditions. Other hydrocarbon biomarkers are novel, and their impact on rice production and storage remains to be elucidated. In conclusion, our findings highlight the ability to rapidly discriminate white rice from Korea and China. The developed method maybe useful for the authenticity and quality control of white rice. Copyright © 2017. Published by Elsevier B.V.

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.

Selective Emitters for High Efficiency TPV Conversion: Materials Preparation and Characterisation

NASA Astrophysics Data System (ADS)

Diso, D.; Licciulli, A.; Bianco, A.; Leo, G.; Torsello, G.; Tundo, S.; De Risi, A.; Mazzer, M.

2003-01-01

Optimising the spectral emissivity of the IR radiation source in a TPV generator is one of the crucial steps towards high efficiency TPV conversion. In this paper we present different approaches to the preparation of selective emitters to be coupled to high efficiency photovoltaic cells. The emitters are designed to work at a temperature of about 1500K and they have been prepared to be used either as external coatings for the burner or as a structural material for the burner itself. Composite ceramics containing rare earth cations, prepared by slip-casting, with various concentration of rare earths were prepared by Slip Casting and Slurry Coating. Rare earth oxides have been incorporated into different oxide matrices, namely Silica, Alumina, Zirconia and their combination. The final aim was to find the material that exhibits the best performance in terms of both high selective power emission, good efficiency along with acceptable thermo-structural properties (high temperature thermal shock resistance, good strength, no creep). The power density emitted by samples as function of the temperature has been tested in the range 1000nm-5000nm. The high temperature emission measurements and the structural tests indicate that a good compromise between the functional and the thermo-structural properties may be reached. The results of the tests on the emitter coatings carried out in a TPV generator at the operating conditions are also presented in this paper.

Processing, Mechanical and Optical Properties of Additive-Free ZrC Ceramics Prepared by Spark Plasma Sintering.

PubMed

Musa, Clara; Licheri, Roberta; Orrù, Roberto; Cao, Giacomo; Sciti, Diletta; Silvestroni, Laura; Zoli, Luca; Balbo, Andrea; Mercatelli, Luca; Meucci, Marco; Sani, Elisa

2016-06-18

In the present study, nearly fully dense monolithic ZrC samples are produced and broadly characterized from microstructural, mechanical and optical points of view. Specifically, 98% dense products are obtained by Spark Plasma Sintering (SPS) after 20 min dwell time at 1850 °C starting from powders preliminarily prepared by Self-propagating High-temperature Synthesis (SHS) followed by 20 min ball milling. A prolonged mechanical treatment up to 2 h of SHS powders does not lead to appreciable benefits. Vickers hardness of the resulting samples (17.5 ± 0.4 GPa) is reasonably good for monolithic ceramics, but the mechanical strength (about 250 MPa up to 1000 °C) could be further improved by suitable optimization of the starting powder characteristics. The very smoothly polished ZrC specimen subjected to optical measurements displays high absorption in the visible-near infrared region and low thermal emittance at longer wavelengths. Moreover, the sample exhibits goodspectral selectivity (2.1-2.4) in the 1000-1400 K temperature range. These preliminary results suggest that ZrC ceramics produced through the two-step SHS/SPS processing route can be considered as attractive reference materials for the development of innovative solar energy absorbers.

Label-Free Electrical Immunosensor for Highly Sensitive and Specific Detection of Microcystin-LR in Water Samples.

PubMed

Tan, Feng; Saucedo, Nuvia Maria; Ramnani, Pankaj; Mulchandani, Ashok

2015-08-04

Microcystin-LR (MCLR) is one of the most commonly detected and toxic cyclic heptapeptide cyanotoxins released by cyanobacterial blooms in surface waters, for which sensitive and specific detection methods are necessary to carry out its recognition and quantification. Here, we present a single-walled carbon nanotube (SWCNTs)-based label-free chemiresistive immunosensor for highly sensitive and specific detection of MCLR in different source waters. MCLR was initially immobilized on SWCNTs modified interdigitated electrode, followed by incubation with monoclonal anti-MCLR antibody. The competitive binding of MCLR in sample solutions induced departure of the antibody from the antibody-antigen complexes formed on SWCNTs, resulting in change in the conductivity between source and drain of the sensor. The displacement assay greatly improved the sensitivity of the sensor compared with direct immunoassay on the same device. The immunosensor exhibited a wide linear response to log value of MCLR concentration ranging from 1 to 1000 ng/L, with a detection limit of 0.6 ng/L. This method showed good reproducibility, stability and recovery. The proposed method provides a powerful tool for rapid and sensitive monitoring of MCLR in environmental samples.

Microwave synthesis and electrochemical characterization of Mn/Ni mixed oxide for supercapacitor application

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

Prasankumar, T.; Jose, Sujin P., E-mail: sujamystica@yahoo.com; Ilangovan, R.

Nanostructured Mn/Ni mixed metal oxide was synthesized at ambient temperature by facile microwave irradiation technique. The crystal structure and surface morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. X-ray diffraction analysis confirmed the formation of Mn/Ni mixed oxide in rhombohedral phase and the grain size calculated was found to be 87 nm. The irregular spherical morphology of the prepared sample was exhibited by the SEM images. The characteristic peaks of FTIR at about 630 cm{sup −1} and 749 cm{sup −1} were attributed to the Mn-O and Ni-O stretching vibrations respectively. The presence of both Mn and Ni inmore » the prepared sample was validated by the EDS spectra which in turn confirmed the formation of mixed oxide. Cyclic voltammetry and galvanostatic chargedischarge measurements were employed to investigate the electrochemical performance of the mixed oxide. The cyclic voltammetry curves demonstrated good capacitive performance of the sample in the potential window −0.2V to 0.9V. The charge discharge study revealed the suitability of the prepared mixed oxide for the fabrication of supercapacitor electrode.« less

Simultaneous extraction and preconcentration of uranium and thorium in aqueous samples by new modified mesoporous silica prior to inductively coupled plasma optical emission spectrometry determination.

PubMed

Yousefi, Seyed Reza; Ahmadi, Seyed Javad; Shemirani, Farzaneh; Jamali, Mohammad Reza; Salavati-Niasari, Masoud

2009-11-15

A new synthesized modified mesoporous silica (MCM-41) using 5-nitro-2-furaldehyde (fural) was applied as an effective sorbent for the solid phase extraction of uranium(VI) and thorium(IV) ions from aqueous solution for the measurement by inductively coupled plasma optical emission spectrometry (ICP OES). The influences of some analytical parameters on the quantitative recoveries of the analyte ions were investigated in batch method. Under optimal conditions, the analyte ions were sorbed by the sorbent at pH 5.5 and then eluted with 1.0 mL of 1.0 mol L(-1) HNO(3). The preconcentration factor was 100 for a 100mL sample volume. The limits of detection (LOD) obtained for uranium(VI) and thorium(IV) were 0.3 microg L(-1). The maximum sorption capacity of the modified MCM-41 was found to be 47 and 49 mg g(-1) for uranium(VI) and thorium(IV), respectively. The sorbent exhibited good stability, reusability, high adsorption capacity and fast rate of equilibrium for sorption/desorption of uranium and thorium ions. The applicability of the synthesized sorbent was examined using CRM and real water samples.

Direct Ink Writing of Three-Dimensional (K, Na)NbO3-Based Piezoelectric Ceramics

PubMed Central

Li, Yayun; Li, Longtu; Li, Bo

2015-01-01

A kind of piezoelectric ink was prepared with Li, Ta, Sb co-doped (K, Na)NbO3 (KNN) powders. Piezoelectric scaffolds with diameters at micrometer scale were constructed from this ink by using direct ink writing method. According to the micro-morphology and density test, the samples sintered at 1100 °C for 2 h have formed ceramics completely with a high relative density of 98%. X-ray diffraction (XRD) test shows that the main phase of sintered samples is orthogonal (Na0.52K0.4425Li0.0375)(Nb0.87Sb0.07Ta0.06)O3. The piezoelectric constant d33 of 280 pC/N, dielectric constant ε of 1775, remanent polarization Pr of 18.8 μC/cm2 and coercive field Ec of 8.5 kV/cm prove that the sintered samples exhibit good electrical properties. The direct ink writing method allows one to design and rapidly fabricate piezoelectric structures in complex three-dimensional (3D) shapes without the need for any dies or lithographic masks, which will simplify the process of material preparation and offer new ideas for the design and application of piezoelectric devices. PMID:28788028

Effervescence-assisted dispersive solid-phase extraction using ionic-liquid-modified magnetic β-cyclodextrin/attapulgite coupled with high-performance liquid chromatography for fungicide detection in honey and juice.

PubMed

Wu, Xiaoling; Yang, Miyi; Zeng, Haozhe; Xi, Xuefei; Zhang, Sanbing; Lu, Runhua; Gao, Haixiang; Zhou, Wenfeng

2016-11-01

In this study, a simple effervescence-assisted dispersive solid-phase extraction method was developed to detect fungicides in honey and juice. Most significantly, an innovative ionic-liquid-modified magnetic β-cyclodextrin/attapulgite sorbent was used because its large specific surface area enhanced the extraction capacity and also led to facile separation. A one-factor-at-a-time approach and orthogonal design were employed to optimize the experimental parameters. Under the optimized conditions, the entire extraction procedure was completed within 3 min. In addition, the calibration curves exhibited good linearity, and high enrichment factors were achieved for pure water and honey samples. For the honey samples, the extraction efficiencies for the target fungicides ranged from 77.0 to 94.3% with relative standard deviations of 2.3-5.44%. The detection and quantitation limits were in the ranges of 0.07-0.38 and 0.23-1.27 μg/L, respectively. Finally, the developed technique was successfully applied to real samples, and satisfactory results were achieved. This analytical technique is cost-effective, environmentally friendly, and time-saving. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of maternal serum alpha-foetoprotein assay using dry blood spot samples.

PubMed

González, C; Guerrero, J M; Elorza, F L; Molinero, P; Goberna, R

1988-02-01

The quantification of alpha-foetoprotein in dry blood spots from pregnant women was evaluated, using a conventional radioimmunoassay (RIA) with a monospecific antibody. The stability of alpha-foetoprotein in dry blood spots on filter paper was evaluated with respect to mailing, distances travelled, and the existence of high summer temperatures in our region. The results obtained show that the blood alpha-foetoprotein is stable on dry filter spots sent by mail and is stable for up to four weeks at 4, 25 and 37 degrees C. The analytical method used has a minimal detectable concentration of 10 +/- 1.9 international kilo-units/l. Both inter- and intra-assay variabilities are smaller than 10% and this method can provide results comparable with those of conventional serum assays. Results from dry blood spots and serum samples (the latter analysed by both RIA and two-site enzyme immunoassay) exhibited a good correlation (r = 0.98 and r = 0.97, p less than 0.001). The design of the assay and the nature of the samples make this method suitable for a screening programmes for the antenatal detection of open neural tube defects.

Inhibition properties of propolis extracts to some clinically important enzymes.

PubMed

Baltas, Nimet; Yildiz, Oktay; Kolayli, Sevgi

2016-01-01

The present study was conducted to envisage inhibition effects of propolis on the crucial enzymes, urease, xanthine oxidase (XO) and acetylcholinesterase (AChE). Some of the antioxidant properties of the propolis samples were determined using the total phenolic content (TPE) and total flavonoids in the eight different ethanolic propolis extracts (EPE) samples. Inhibition values of the enzymes were expressed as inhibition concentration (IC 50 ; mg/mL or μg/mL) causing 50% inhibition of the enzymes with donepezil, acetohydroxamic acid and allopurinol as reference inhibitors. All the propolis extracts exhibited variable inhibition effects on these enzymes, but the higher the phenolic contents the lower the inhibitions values (IC 50 = 0.074 to 1.560 mg/mL). IC 50 values of the P5 propolis sample having the highest TPE, obtained from Zonguldak, for AChE, urease and XO were 0.081 ± 0.009, 0.080 ± 0.006 and 0.074 ± 0.011 μg/mL, respectively. The EPE proved to be a good source of inhibitor agents that can be used as natural inhibitors to serve human health.

Graphene oxide bonded fused-silica fiber for solid-phase microextraction-gas chromatography of polycyclic aromatic hydrocarbons in water.

PubMed

Xu, Lili; Feng, Juanjuan; Li, Jubai; Liu, Xia; Jiang, Shengxiang

2012-01-01

A novel chemically bonded graphene oxide/fused-silica fiber was prepared and applied in solid-phase microextraction of six polycyclic aromatic hydrocarbons from water samples coupled with gas chromatography. It exhibited high extraction efficiency and excellent stability. Effects of extraction time, extraction temperature, ionic strength, stirring rate and desorption conditions were investigated and optimized in our work. Detection limits to the six polycyclic aromatic hydrocarbons were less than 0.08 μg/L, and their calibration curves were all linear (R(2)≥0.9954) in the range from 0.05 to 200 μg/L. Single fiber repeatability and fiber-to-fiber reproducibility were less than 6.13 and 15.87%, respectively. This novel fiber was then utilized to analyze two real water samples from the Yellow River and local waterworks, and the recoveries of samples spiked at 1 and 10 μg/L ranged from 84.48 to 118.24%. Compared with other coating materials, this graphene oxide-coated fiber showed many advantages: wide linear range, low detection limit, and good stability in acid, alkali, organic solutions and at high temperature. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization and application of parallel solid-phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry for the determination of 11 aminoglycoside residues in honey and royal jelly.

PubMed

Wang, Xinran; Yang, Shupeng; Li, Yi; Zhang, Jinzhen; Jin, Yue; Zhao, Wen; Zhang, Yongxin; Huang, Jingping; Wang, Peng; Wu, Cuiling; Zhou, Jinhui

2018-03-23

A robust and sensitive method of solid-phase extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established and performed for the simultaneous determination of eleven aminoglycosides (AGs) in royal jelly and honey. After sample extraction by a phosphate buffer containing trichloroacetic acid (TCA) and ethylenediaminetetracetic acid disodium salt (Na 2 EDTA), the extraction solution was subjected to a parallel solid-phase extraction for clean-up prior to the LC-MS/MS analysis. The same method was applied to analyze two completely different matrices, honey and royal jelly. Good sensitivity, repeatability, and recovery were obtained by using the mobile phase without an ion-pairing reagent such as heptafluorobutyric acid (HFBA) or sodium heptanesulfonate. The calibration curves of the honey and royal jelly samples exhibited a good linear response (R 2  > 0.99) at six concentrations in the range of 10-1000 μg/mL. The limit of quantification (LOQ) of the AGs ranged from 10 to 25 μg/kg in the honey and from 12.5 to 25 μg/kg in the royal jelly. The recoveries of the AGs for the honey and royal jelly samples were in the range of 79.48% to 108.95% and 74.61% to 113.70% respectively and the relative standard deviations (RSDs) were between 1.23% and 9.59%, and between 1.51% and 9.98%, respectively. The proposed approach has been allowed in China as a reference method for the simultaneous determination of eleven AGs in honey and royal jelly. Copyright © 2018 Elsevier B.V. All rights reserved.

Microporosity development in phenolic resin-based mesoporous carbons for enhancing CO2 adsorption at ambient conditions

NASA Astrophysics Data System (ADS)

Choma, Jerzy; Jedynak, Katarzyna; Fahrenholz, Weronika; Ludwinowicz, Jowita; Jaroniec, Mietek

2014-01-01

Soft-templating method was used to prepare mesoporous carbons. The synthesis in the presence of hydrochloric and citric acids involved resorcinol and formaldehyde as carbon precursors and triblock copolymer Pluronic F127 as a template. The as-synthesized samples underwent carbonization in flowing nitrogen at various temperatures; namely 600 °C, 700 °C and 800 °C. Two routes were used to develop microporosity in the mesoporous carbons studied. The first one involved introduction of tetraethyl orthosilicate to the reaction system. After silica dissolution with NaOH, an increase in microporosity was observed. The second method, chemical activation with KOH at 700 °C, was explored as an alternative approach to create microporosity. It is noteworthy that the TEOS addition not only led to the development of microporosity but also to some improvement of mesoporosity. The post-synthesis KOH activation resulted in more significant increase in the microporosity as compared to the samples obtained by TEOS-assisted synthesis. The mesopore volume was somewhat lower for activated carbons as compared to that in mesoporous carbons. Both methods resulted in micro-mesoporous carbons with good adsorption properties; for instance, in the case of carbons prepared in the presence of TEOS, the best sample exhibited BET surface area of 1463 m2/g and the total pore volume of 1.31 cm3/g. For the KOH activated carbons the best adsorption parameters were as follows: the specific surface area = 1906 m2/g, and the total pore volume = 0.98 cm3/g. Both procedures used for microporosity development afforded carbons with good adsorption properties that can be useful for applications such as CO2 adsorption, air and water purification.

Two-step oxalate approach for the preparation of high performance LiNi0.5Mn1.5O4 cathode material with high voltage

NASA Astrophysics Data System (ADS)

Liu, Zushan; Jiang, Yangmei; Zeng, Xiaoyuan; Xiao, Guan; Song, Huiyu; Liao, Shijun

2014-02-01

A high voltage cathode material, LiNi0.5Mn1.5O4, is synthesized with a two-step approach, in which the nickel-manganese oxalate precipitate is firstly obtained by adding oxalic acid to the solution of nickel and manganese ions precursors, followed by calcining the oxalates to obtain spinel nickel-manganese oxide, incorporating lithium ions with ball milling and calcining at 900 °C for 15 h. The materials are characterized with TG, XRD, SEM, BET and FTIR; it is revealed that both nickel-manganese oxide and final LiNi0.5Mn1.5O4 have well defined spinel structure. The LiNi0.5Mn1.5O4 spinel materials exhibit high capacities and good cyclic stability, the capacity of the materials is in the range from 126 to 136 mAh -1, depending on the calcining temperatures. The sample calcined at an optimal temperature of 900 °C exhibits best performance, the capacity is high up to 136 mAh g-1 at tenth cycle and the capacity retention after 50 cycles is 93%. For the sample prepared by mixing and milling oxalate with lithium salt, the discharge capacity is only 115 mAh g-1. We suggest that the spinel oxide derived from oxalate may play an important role for the high performance and high stability of the final cathode materials.

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.

Tunable microwave absorbing nano-material for X-band applications

NASA Astrophysics Data System (ADS)

Sadiq, Imran; Naseem, Shahzad; Ashiq, Muhammad Naeem; Khan, M. A.; Niaz, Shanawer; Rana, M. U.

2016-03-01

The effect of rare earth elements substitution in Sr1.96RE0.04Co2Fe27.80Mn0.2O46 (RE=Ce, Gd, Nd, La and Sm) X-type hexagonal ferrites prepared by using sol gel autocombustion method was studied. The XRD and FTIR analysis show the single phase of the prepared material. The lattice constants a (Å) and c (Å) varies with the additives. The particle size measured by Scherer formula for all the samples varies in the range of 54-100 nm and confirmed by the TEM analysis. The average grain size measured by SEM analysis lies in the range of 0.672-1.01 μm for all the samples. The Gd-substituted ferrite has higher value of coercivity (526.06 G) among all the samples which could be a good material for longitudinal recording media. The results also indicate that the Gd-substituted sample has maximum reflection loss of -25.2 dB at 11.878 GHz, can exhibit the best microwave absorption properties among all the substituted samples. Furthermore, the minimum value of reflection loss shifts towards the lower and higher frequencies with the substitution of rare earth elements which confirms that the microwave absorption properties can be tuned with the substitution of rare earth elements in pure ferrites. The peak value of attenuation constant at higher frequency agrees well the reflection loss data.

Iron oxide functionalized graphene nano-composite for dispersive solid phase extraction of chemical warfare agents from aqueous samples.

PubMed

Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Tak, Vijay; Goud, D Raghavender; Dubey, D K; Pardasani, Deepak

2015-05-15

Present study deals with the preparation and evaluation of graphene based magnetic nano-composite for dispersive solid phase extraction of Chemical Weapons Convention (CWC) relevant chemicals from aqueous samples. Nano-composite, Fe3O4@SiO2-G was synthesized by covalently bonding silica coated Fe3O4 onto the graphene sheets. Nerve agents (NA), Sulfur mustard (SM) and their non-toxic environmental markers were the target analytes. Extraction parameters like amount of sorbent, extraction time and desorption conditions were optimized. Dispersion of 20 milligram of sorbent in 200mL of water sample for 20min. followed by methanol/chloroform extraction produced average to good recoveries (27-94%) of targeted analytes. Recoveries of real agents exhibited great dependency upon sample pH and ionic strength. Sarin produced maximum recovery under mild acidic conditions (56% at pH 5) while VX demanded alkaline media (83% at pH 9). Salts presence in the aqueous samples was found to be advantageous, raising the recoveries to as high as 94% for SM. Excellent limits of detection (LOD) for sulphur mustard and VX (0.11ngmL(-1) and 0.19ngmL(-1) respectively) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of bipolar electric fatigue on polarization switching in lead-zirconate-titanate ceramics

NASA Astrophysics Data System (ADS)

Zhukov, Sergey; Fedosov, Sergey; Glaum, Julia; Granzow, Torsten; Genenko, Yuri A.; von Seggern, Heinz

2010-07-01

From comparison of experimental results on polarization switching in fresh and electrically fatigued lead-zirconate-titanate (PZT) over a wide range of applied fields and switching times it is concluded that fatigue alters the local field distribution inside the sample due to the generation of discrete defects, such as voids and cracks. Such defects have a strong influence on the overall electric field distribution by their shape and dielectric permittivity. On this hypothesis, a new phenomenological model of polarization switching in fatigued PZT is proposed. The model assumes that the fatigued sample can be composed of different local regions which exhibit different field strengths but otherwise can be considered as unfatigued. Consequently the temporal response of a fatigued sample is assumed to be the superposition of the field-dependent temporal responses of unfatigued samples weighted by their respective volume fraction. A certain part of the volume is excluded from the overall switching process due to the domain pinning even at earlier stages of fatigue, which can be recovered by annealing. Suitability of the proposed model is demonstrated by a good correlation between experimental and calculated data for differently fatigued samples. Plausible cause of the formation of such regions is the generation of defects such as microcracks and the change in electrical properties at imperfections such as pores or voids.

Amine-functionalized mesoporous polymer as potential sorbent for nickel preconcentration from electroplating wastewater.

PubMed

Islam, Aminul; Zaidi, Noushi; Ahmad, Hilal; Kumar, Suneel

2015-05-01

In this study, mesoporous glycidyl methacrylate-divinylbenzene-based chelating resin was synthesized and grafted with diethylenetriamine through epoxy ring-opening reaction. The synthesized resin was characterized by elemental analysis, infrared spectroscopy, surface area and pore size analysis, scanning electron microscopy, energy-dispersive spectroscopy, and thermogravimetry. The resin was used for the first time as an effective sorbent for the preconcentration of nickel in electroplating wastewater samples. The analytical variables like pH, flow rate for sorption/desorption, and eluate selection were systematically investigated and optimized. The uniform and monolayer sorption behavior of resin for nickel was proved by an evident fit of the equilibrium data to a Langmuir isotherm model. Under optimized conditions, the resin was observed to show a good sorption capacity of 20.25 mg g(-1) and >96% recovery of nickel even in the presence of a large number of competitive matrix ions. Its ability to extract trace amount of nickel was exhibited by low preconcentration limit (5.9 μg L(-1)). The calibration curve was found to be linear (R(2) = 0.998) in the concentration range of 6.0-400.0 μg L(-1). Coefficient of variation of less than 5 for all the analysis indicated good reproducibility. The reliability was evaluated by the analysis of standard reference material (SRM) and recovery experiments. The applicability of the resin for the systematic preconcentration of nickel is substantiated by the analysis of electroplating wastewater and river water samples. Graphical abstract ᅟ.

Identification of Phenolic Acids and Flavonoids in Monofloral Honey from Bangladesh by High Performance Liquid Chromatography: Determination of Antioxidant Capacity

PubMed Central

Moniruzzaman, Mohammed; Yung An, Chua; Rao, Pasupuleti Visweswara; Hawlader, Mohammad Nurul Islam; Azlan, Siti Amirah Binti Mohd; Sulaiman, Siti Amrah; Gan, Siew Hua

2014-01-01

The aim of the present study was to characterize the phenolic acids, flavonoids, and antioxidant properties of monofloral honey collected from five different districts in Bangladesh. A new high performance liquid chromatography (HPLC) equipped with a UV detector method was developed for the identification of the phenolic acids and flavonoids. A total of five different phenolic acids were identified, with the most abundant being caffeic acid, benzoic acid, gallic acid, followed by chlorogenic acid and trans-cinnamic acid. The flavonoids, kaempferol, and catechin were most abundant, followed by myricetin and naringenin. The mean moisture content, total sugar content, and color characteristics of the honey samples were 18.36 ± 0.95%, 67.40 ± 5.63 g/100 g, and 129.27 ± 34.66 mm Pfund, respectively. The mean total phenolic acids, total flavonoid content, and proline content were 199.20 ± 135.23, 46.73 ± 34.16, and 556.40 ± 376.86 mg/kg, respectively, while the mean FRAP values and DPPH radical scavenging activity were 327.30 ± 231.87 μM Fe (II)/100 g and 36.95 ± 20.53%, respectively. Among the different types of honey, kalijira exhibited the highest phenolics and antioxidant properties. Overall, our study confirms that all the investigated honey samples are good sources of phenolic acids and flavonoids with good antioxidant properties. PMID:25045696

Facile synthesis of Ag/ZnO heterostructures assisted by UV irradiation: Highly photocatalytic property and enhanced photostability

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

Yang, Zhongmei, E-mail: kalimodor@163.com; Zhang, Ping; Ding, Yanhuai

2011-10-15

Highlights: {yields} Fabrication of Ag/ZnO heterostructure between the two incompatible phases is realized under UV irradiation in the absence of surfactant. {yields} The synthetic method is facile, low cost, and low carbon, which depends on the photogenerated electrons produced by ZnO under UV light. {yields} Photocatalytic property of the as-synthesized samples is 3.0 times as good as the pure ZnO synthesized under the same condition or the commercial TiO{sub 2} (Degussa, P-25). {yields} The heterostructures exhibit good durability without significant change in the activity even after the third cycle compared to the pure ZnO. -- Abstract: We report a newmore » method to synthesize Ag/ZnO heterostructures assisted by UV irradiation. The formation of Ag/ZnO heterostructures depends on photogenerated electrons produced by ZnO under UV light to reduce high valence silver. Functional property of the Ag/ZnO heterostructures is evaluated by photodegradation of methylene blue (MB) under UV illumination. Results of photodegradation tests reveal that the optimal photocatalytic activity of as-syntheszied samples is about 1.5 times higher than the pure ZnO synthesized in the same condition or commercial TiO{sub 2} (P-25), showing the advantage of the unique structure in the Ag/ZnO heterostructure. Besides, due to the reduced activation of surface oxygen atom, photocatalytic activity of the photocatalysts has no evident decrease even after three recycles.« less

Magnetic immunoassay coupled with inductively coupled plasma mass spectrometry for simultaneous quantification of alpha-fetoprotein and carcinoembryonic antigen in human serum

NASA Astrophysics Data System (ADS)

Zhang, Xing; Chen, Beibei; He, Man; Zhang, Yiwen; Xiao, Guangyang; Hu, Bin

2015-04-01

The absolute quantification of glycoproteins in complex biological samples is a challenge and of great significance. Herein, 4-mercaptophenylboronic acid functionalized magnetic beads were prepared to selectively capture glycoproteins, while antibody conjugated gold and silver nanoparticles were synthesized as element tags to label two different glycoproteins. Based on that, a new approach of magnetic immunoassay-inductively coupled plasma mass spectrometry (ICP-MS) was established for simultaneous quantitative analysis of glycoproteins. Taking biomarkers of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) as two model glycoproteins, experimental parameters involved in the immunoassay procedure were carefully optimized and analytical performance of the proposed method was evaluated. The limits of detection (LODs) for AFP and CEA were 0.086 μg L- 1 and 0.054 μg L- 1 with the relative standard deviations (RSDs, n = 7, c = 5 μg L- 1) of 6.5% and 6.2% for AFP and CEA, respectively. Linear range for both AFP and CEA was 0.2-50 μg L- 1. To validate the applicability of the proposed method, human serum samples were analyzed, and the obtained results were in good agreement with that obtained by the clinical chemiluminescence immunoassay. The developed method exhibited good selectivity and sensitivity for the simultaneous determination of AFP and CEA, and extended the applicability of metal nanoparticle tags based on ICP-MS methodology in multiple glycoprotein quantifications.

Human bony labyrinth is an indicator of population history and dispersal from Africa

PubMed Central

Ponce de León, Marcia S.; Koesbardiati, Toetik; Weissmann, John David; Milella, Marco; Reyna-Blanco, Carlos S.; Suwa, Gen; Kondo, Osamu; Malaspinas, Anna-Sapfo; White, Tim D.; Zollikofer, Christoph P. E.

2018-01-01

The dispersal of modern humans from Africa is now well documented with genetic data that track population history, as well as gene flow between populations. Phenetic skeletal data, such as cranial and pelvic morphologies, also exhibit a dispersal-from-Africa signal, which, however, tends to be blurred by the effects of local adaptation and in vivo phenotypic plasticity, and that is often deteriorated by postmortem damage to skeletal remains. These complexities raise the question of which skeletal structures most effectively track neutral population history. The cavity system of the inner ear (the so-called bony labyrinth) is a good candidate structure for such analyses. It is already fully formed by birth, which minimizes postnatal phenotypic plasticity, and it is generally well preserved in archaeological samples. Here we use morphometric data of the bony labyrinth to show that it is a surprisingly good marker of the global dispersal of modern humans from Africa. Labyrinthine morphology tracks genetic distances and geography in accordance with an isolation-by-distance model with dispersal from Africa. Our data further indicate that the neutral-like pattern of variation is compatible with stabilizing selection on labyrinth morphology. Given the increasingly important role of the petrous bone for ancient DNA recovery from archaeological specimens, we encourage researchers to acquire 3D morphological data of the inner ear structures before any invasive sampling. Such data will constitute an important archive of phenotypic variation in present and past populations, and will permit individual-based genotype–phenotype comparisons. PMID:29610337

Frequency Effects on ESL Compositional Multi-Word Sequence Processing

ERIC Educational Resources Information Center

Supasiraprapa, Sarut

2017-01-01

The current study investigated whether adult native English speakers and English-as-a-second-language (ESL) learners exhibit sensitivity to compositional English multi-word sequences, which have a meaning derivable from word parts (e.g., don't have to worry as opposed to sequences like He left the US for good, where for good cannot be taken apart…

Quality of life and psychological health indicators in the national social life, health, and aging project.

PubMed

Shiovitz-Ezra, Sharon; Leitsch, Sara; Graber, Jessica; Karraker, Amelia

2009-11-01

The National Social Life, Health, and Aging Project (NSHAP) measures seven indicators of quality of life (QoL) and psychological health. The measures used for happiness, self-esteem, depression, and loneliness are well established in the literature. Conversely, measures of anxiety, stress, and self-reported emotional health were modified for their use in this unique project. The purpose of this paper is to provide (a) an overview of NSHAP's QoL assessment and (b) evidence for the adequacy of the modified measures. First, we examined the psychometric properties of the modified measures. Second, the established QoL measures were used to examine the concurrent validity of the modified measures. Finally, gender- and age-group differences were examined for each modified measure. The anxiety index exhibited good internal reliability and concurrent validity. Consistent with the literature, a single-factor structure best fit the data. Stress was satisfactory in terms of concurrent validity but with only fair internal consistency. Self-reported emotional health exhibited good concurrent validity and moderate external validity. The modified indices used in NSHAP tended to exhibit good internal reliability and concurrent validity. These measures can confidently be used in the exploration of QoL and psychological health in later life and its many correlates.

Wear behavior of austenite containing plate steels

NASA Astrophysics Data System (ADS)

Hensley, Christina E.

As a follow up to Wolfram's Master of Science thesis, samples from the prior work were further investigated. Samples from four steel alloys were selected for investigation, namely AR400F, 9260, Hadfield, and 301 Stainless steels. AR400F is martensitic while the Hadfield and 301 stainless steels are austenitic. The 9260 exhibited a variety of hardness levels and retained austenite contents, achieved by heat treatments, including quench and tempering (Q&T) and quench and partitioning (Q&P). Samples worn by three wear tests, namely Dry Sand/Rubber Wheel (DSRW), impeller tumbler impact abrasion, and Bond abrasion, were examined by optical profilometry. The wear behaviors observed in topography maps were compared to the same in scanning electron microscopy micrographs and both were used to characterize the wear surfaces. Optical profilometry showed that the scratching abrasion present on the wear surface transitioned to gouging abrasion as impact conditions increased (i.e. from DSRW to impeller to Bond abrasion). Optical profilometry roughness measurements were also compared to sample hardness as well as normalized volume loss (NVL) results for each of the three wear tests. The steels displayed a relationship between roughness measurements and observed wear rates for all three categories of wear testing. Nanoindentation was used to investigate local hardness changes adjacent to the wear surface. DSRW samples generally did not exhibit significant work hardening. The austenitic materials exhibited significant hardening under the high impact conditions of the Bond abrasion wear test. Hardening in the Q&P materials was less pronounced. The Q&T microstructures also demonstrated some hardening. Scratch testing was performed on samples at three different loads, as a more systematic approach to determining the scratching abrasion behavior. Wear rates and scratch hardness were calculated from scratch testing results. Certain similarities between wear behavior in scratch testing and DSRW samples were observed. Different microstructures exhibited different scratching behaviors. Martensitic microstructures exhibited chipping and cracking, whereas Q&P microstructures exhibited limited or no chipping. The Q&P samples exhibited more deformation at greater loads and hardness levels than the martensitic microstructures. Austenitic microstructures exhibited significant deformation adjacent to the scratches.

Complexation-Based Detection of Nickel(II) at a Graphene-Chelate Probe in the Presence of Cobalt and Zinc by Adsorptive Stripping Voltammetry

PubMed Central

Pokpas, Keagan; Jahed, Nazeem; Baker, Priscilla G.

2017-01-01

The adsorptive stripping voltammetric detection of nickel and cobalt in water samples at metal film electrodes has been extensively studied. In this work, a novel, environmentally friendly, metal-free electrochemical probe was constructed for the ultra-trace determination of Ni2+ in water samples by Adsorptive Cathodic Stripping Voltammetry (AdCSV). The electrochemical platform is based on the adsorptive accumulation of Ni2+ ions directly onto a glassy carbon electrode (GCE) modified with dimethylglyoxime (DMG) as chelating agent and a Nafion-graphene (NGr) nanocomposite to enhance electrode sensitivity. The nafion-graphene dimethylglyoxime modified glassy carbon electrode (NGr-DMG-GCE) shows superior detection capabilities as a result of the improved surface-area-to-volume ratio and enhanced electron transfer kinetics following the incorporation of single layer graphene, while limiting the toxic effects of the sensor by removal of the more common mercury, bismuth and lead films. Furthermore, for the first time the NGr-DMG-GCE, in the presence of common interfering metal ions of Co2+ and Zn2+ demonstrates good selectivity and preferential binding towards the detection of Ni2+ in water samples. Structural and morphological characterisation of the synthesised single layer graphene sheets was conducted by Raman spectrometry, HRTEM and HRSEM analysis. The instrumental parameters associated with the electrochemical response, including accumulation potential and accumulation time were investigated and optimised in addition to the influence of DMG and graphene concentrations. The NGr-DMG-GCE demonstrated well resolved, reproducible peaks, with RSD (%) below 5% and a detection limit of 1.5 µg L−1 for Ni2+ reduction at an accumulation time of 120 s. The prepared electrochemical sensor exhibited good detection and quantitation towards Ni2+ detection in tap water samples, well below 0.1 mg L−1 set by the WHO and EPA standards. This is comparable to the South African drinking water guidelines of 0.15 mg L−1. PMID:28757588

Ionic liquids intercalated in montmorillonite as the sorptive phase for the extraction of low-polarity organic compounds from water by rotating-disk sorptive extraction.

PubMed

Fiscal-Ladino, Jhon A; Obando-Ceballos, Mónica; Rosero-Moreano, Milton; Montaño, Diego F; Cardona, Wilson; Giraldo, Luis F; Richter, Pablo

2017-02-08

Montmorillonite (MMT) clays were modified by the intercalation into their galleries of ionic liquids (IL) based on imidazolium quaternary ammonium salts. This new eco-materials exhibited good features for use as a sorptive phase in the extraction of low-polarity analytes from aqueous samples. Spectroscopic analyses of the modified clays were conducted and revealed an increase in the basal spacing and a shifting of the reflection plane towards lower values as a consequence of the effective intercalation of organic cations into the MMT structure. The novel sorbent developed herein was assayed as the sorptive phase in rotating-disk sorptive extraction (RDSE), using polychlorinated biphenyls (PCBs), representative of low-polarity pollutants, as model analytes. The final determination was made by gas chromatography with electron capture detection. Among the synthetized sorptive phases, the selected system for analytical purposes consisted of MMT modified with the 1-hexadecyl-3-methylimidazolium bromide (HDMIM-Br) IL. Satisfactory analytical features were achieved using a sample volume of 5 mL: the relative recoveries from a wastewater sample were higher than 80%, the detection limits were between 3 ng L -1 and 43 ng L -1 , the precision (within-run precision) expressed as the relative standard deviation ranged from 2% to 24%, and the enrichment factors ranged between 18 and 28. Using RDSE, the extraction efficiency achieved for the selected MMT-HDMIM-Br phase was compared with other commercial solid phases/supports, such as polypropylene, polypropylene with 1-octanol (as a supported liquid membrane), octadecyl (C18) and octyl (C8), and showed the highest response for all the studied analytes. Under the optimized extraction conditions, this new device was applied in the analysis of the influent of a wastewater treatment plant in Santiago (Chile), demonstrating its applicability through the good recoveries and precision achieved with real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of hydrocolloid on rheology and microstructure of high-protein soy desserts.

PubMed

Arancibia, Carla; Bayarri, Sara; Costell, Elvira

2015-10-01

Due to the rheological and structural basis of texture perceived in semisolid foods, the aim of this work was to study the effects of two thickening agents, on rheology and microstructure of soy protein desserts. As rheological parameter values may not be enough to explain the possible perceived texture differences, the effect of composition on two instrumental indexes of oral consistency (apparent viscosity at 50 s(-1) and complex dynamic viscosity at 8 Hz) was also studied. Samples were prepared at two soy protein isolate (SPI) concentrations (6 and 8 % w/w), each with four modified starch concentrations (2, 2.5, 3 and 3.5 % w/w) or four Carboxymethyl cellulose (CMC) concentrations (0.3, 0.5, 0.7 and 0.9 % w/w). Two more samples without added thickener were prepared as control samples. The flow curves of all systems showed a typical shear-thinning behaviour and observable hysteresis loops. Control sample flow fitted well with the Ostwald-de Waele model and the flow of samples with thickener to the Herschel-Bulkley model. Viscoelastic properties of samples ranged from fluid-like to weak gel, depending on thickener and SPI concentrations. Starch-based samples exhibited a globular structure with SPI aggregates distributed among starch granules. In CMC-based samples, a coarse stranded structure with SPI aggregates partially embedded was observed. Variation of the two thickness index values with composition showed a similar trend with good correlation between them (R(2) = 0.92). Soy desserts with different composition but with similar rheological behaviour or instrumental thickness index values can be obtained.

Effect of chlorpyrifos on the inhibition of the enzyme acetylcholinesterase by cross-linking in water-supply samples and milk from dairy cattle.

PubMed

Catalina Rodríguez, Diana; Carvajal, Stephanie; Peñuela, Gustavo

2013-07-15

A methodology for the determination of chlorpyrifos in water-supply samples and in milk from dairy cattle was developed. An amperometric biosensor was used to inhibit the enzyme acetylcholinesterase (AChE), which was immobilized by the cross-linking method (crosslinks between the enzyme and the sensor). The potential applied, the amount of enzyme to be immobilized and the acetylthiocholine (ACTh) concentration were optimized before calibration and analysis of the samples was performed. The concentration of chlorpyrifos was determined in the range of 1.0×10(-6) M to 5.0×10(-2) M with a detection limit of 5.0×10(-6) M. Spiked water samples showed high recoveries (91.32% and 93.98% for low and high chlorpyrifos levels, respectively), while milk samples exhibited a matrix effect with recoveries of 82.81% and 79.77% for high and low chlorpyrifos levels, respectively. The average concentration of chlorpyrifos in the water supply samples (5.11×10(-6) M), determined using the biosensor, was compared using gas chromatography and gave an average value of 3.04×10(-6) M. The results allow it to be concluded that although chromatographic methods are still more exact, biosensors are promising tools for the determination of analytes in the field, as they have a low cost, a reduced analysis time and good reproducibility in the data. Copyright © 2013 Elsevier B.V. All rights reserved.

Non-enzymatic glucose sensing properties of MoO3 nanorods: experimental and density functional theory investigations

NASA Astrophysics Data System (ADS)

Sharma, Maneesha; Gangan, Abhijeet; Chakraborty, Brahmananda; Sekhar Rout, Chandra

2017-11-01

We report the growth of monoclinic MoO3 nanorods by a simple and highly reproducible hydrothermal method. Structural and morphological studies provide significant insights about the phase and crystalline structure of the synthesized samples. Further, the non-enzymatic glucose sensing properties were investigated and the MoO3 nanorods exhibited a sensitivity of 15.4 µA µM-1 cm-2 in the 5-175 µM linear range. Also, a quick response time of 8 s towards glucose molecules was observed, exhibiting an excellent electrochemical activity. We have also performed density functional theory (DFT) simulations to qualitatively support our experimental observations by investigating the interactions and charge-transfer mechanism of glucose on MoO3. There is a strong interaction between glucose and the MoO3 surface due to charge transfer from a bonded O atom of glucose to a Mo atom of MoO3 resulting in a strong hybridization between the p orbital of O and d orbital of Mo. Thus, the MoO3 nanorod-based electrodes are found to be good glucose sensing materials for practical industrial applications.

Self-Supporting, Hydrophobic, Ionic Liquid-Based Reference Electrodes Prepared by Polymerization-Induced Microphase Separation

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

Chopade, Sujay A.; Anderson, Evan L.; Schmidt, Peter W.

Interfaces of ionic liquids and aqueous solutions exhibit stable electrical potentials over a wide range of aqueous electrolyte concentrations. This makes ionic liquids suitable as bridge materials that separate in electroanalytical measurements the reference electrode from samples with low and/or unknown ionic strengths. However, methods for the preparation of ionic liquid-based reference electrodes have not been explored widely. We have designed a convenient and reliable synthesis of ionic liquid-based reference electrodes by polymerization-induced microphase separation. This technique allows for a facile, single-pot synthesis of ready-to-use reference electrodes that incorporate ion conducting nanochannels filled with either 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-dodecyl-3-methylimidazolium bis(trifluoromethylmore » sulfonyl)imide as ionic liquid, supported by a mechanically robust cross-linked polystyrene phase. This synthesis procedure allows for the straightforward design of various reference electrode geometries. These reference electrodes exhibit a low resistance as well as good reference potential stability and reproducibility when immersed into aqueous solutions varying from deionized, purified water to 100 mM KCl, while requiring no correction for liquid junction potentials.« less

Is Charismatic Leadership Effective When Workers Are Pressured To Be Good Citizens?

PubMed

Horn, Dewaynna; Mathis, Christopher J; Robinson, Sammie L; Randle, Natasha

2015-01-01

Prior research has explored how employees' perceptions of their leaders impact their work attitudes and behaviors. Studies have shown that charismatic leaders motivate individuals to be more engaged and to exhibit more organizational citizenship behaviors. This study considers how a moderator, citizenship pressure, affects how charismatic leaders might inspire their followers to go above and beyond and be more engaged in their work. Using a sample of 243 workers, this study's findings show that charismatic leadership has a stronger positive effect on job engagement when employees perceive less citizenship pressure. Citizenship pressure did not moderate the relationship between charismatic leadership and organizational citizenship behavior. Implications of this study include an examination of the moderating influence of citizenship pressure, a relatively new construct. Practically, the implications may shed some light on leadership factors that encourage increased effort from employees and greater employee engagement. More specifically, findings suggest that persons are motivated to exhibit more OCBs to meet high expectations of charismatic leaders. However, when seeking engagement, feeling pressure to perform these OCBs has a reverse effect as more job engagement results with less citizenship pressure. Future research suggestions and limitations are discussed.

Membrane Introduction Mass Spectrometry Combined with an Orthogonal Partial-Least Squares Calibration Model for Mixture Analysis.

PubMed

Li, Min; Zhang, Lu; Yao, Xiaolong; Jiang, Xingyu

2017-01-01

The emerging membrane introduction mass spectrometry technique has been successfully used to detect benzene, toluene, ethyl benzene and xylene (BTEX), while overlapped spectra have unfortunately hindered its further application to the analysis of mixtures. Multivariate calibration, an efficient method to analyze mixtures, has been widely applied. In this paper, we compared univariate and multivariate analyses for quantification of the individual components of mixture samples. The results showed that the univariate analysis creates poor models with regression coefficients of 0.912, 0.867, 0.440 and 0.351 for BTEX, respectively. For multivariate analysis, a comparison to the partial-least squares (PLS) model shows that the orthogonal partial-least squares (OPLS) regression exhibits an optimal performance with regression coefficients of 0.995, 0.999, 0.980 and 0.976, favorable calibration parameters (RMSEC and RMSECV) and a favorable validation parameter (RMSEP). Furthermore, the OPLS exhibits a good recovery of 73.86 - 122.20% and relative standard deviation (RSD) of the repeatability of 1.14 - 4.87%. Thus, MIMS coupled with the OPLS regression provides an optimal approach for a quantitative BTEX mixture analysis in monitoring and predicting water pollution.

Preparation and Properties of Surface-Coated HMX with Viton and Graphene Oxide

NASA Astrophysics Data System (ADS)

Wang, Jingyu; Ye, Baoyun; An, Chongwei; Wu, Bidong; Li, Hequn; Wei, Yanju

2016-07-01

To improve the safety performance of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) particles, the new carbon material graphene oxide (GO) and Viton were used to coat HMX via a solvent-slurry process. For comparison, the HMX/Viton/graphite (HMX/Viton/G) and HMX/Viton composites were also prepared by the same process. Atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC) were employed to characterize the morphology, composition, and thermal decomposition of samples. The impact sensitivity and shock wave sensitivity of HMX-based composites were also measured and analyzed. The results of SEM, XRD, and XPS indicate that the cladding layer of HMX-based composites is successfully constructed. HMX/Viton/GO composites exhibit better thermal stability compared to HMX and HMX/Viton. The results show that both impact and shock wave sensitivities of HMX/Viton/GO composites are much lower than that of HMX/Viton. In addition, GO sheets exhibit a better desensitizing effect than G sheets. These combined properties suggest that nano-GO has good compatibility with explosives and can be utilized as a desensitizer in HMX particles.

Gancidin W, a potential low-toxicity antimalarial agent isolated from an endophytic Streptomyces SUK10

PubMed Central

Zin, Noraziah Mohamad; Baba, Mohd Shukri; Zainal-Abidin, Abu Hassan; Latip, Jalifah; Mazlan, Noor Wini; Edrada-Ebel, RuAngelie

2017-01-01

Endophytic Streptomyces strains are potential sources for novel bioactive molecules. In this study, the diketopiperazine gancidin W (GW) was isolated from the endophytic actinobacterial genus Streptomyces, SUK10, obtained from the bark of Shorea ovalis tree, and it was tested in vivo against Plasmodium berghei PZZ1/100. GW exhibited an inhibition rate of nearly 80% at 6.25 and 3.125 μg kg−1 body weight on day four using the 4-day suppression test method on male ICR strain mice. Comparing GW at both concentrations with quinine hydrochloride and normal saline as positive and negative controls, respectively, 50% of the mice treated with 3.125 μg kg−1 body weight managed to survive for more than 11 months after infection, which almost reached the life span of normal mice. Biochemical tests of selected enzymes and proteins in blood samples of mice treated with GW were also within normal levels; in addition, no abnormalities or injuries were found on internal vital organs. These findings indicated that this isolated bioactive compound from Streptomyces SUK10 exhibits very low toxicity and is a good candidate for potential use as an antimalarial agent in an animal model. PMID:28223778

Rhenium tetrazolato complexes coordinated to thioalkyl-functionalised phenanthroline ligands: synthesis, photophysical characterisation, and incubation in live HeLa cells.

PubMed

Werrett, Melissa V; Wright, Phillip J; Simpson, Peter V; Raiteri, Paolo; Skelton, Brian W; Stagni, Stefano; Buckley, Alysia G; Rigby, Paul J; Massi, Massimiliano

2015-12-21

Three new complexes of formulation fac-[Re(CO)3(diim)L], where diim is either 1,10-phenanthroline or 1,10-phenanthroline functionalised at position 5 by a thioalkyl chain, and L is either a chloro or aryltetrazolato ancillary ligand, were synthesised and photophysically characterised. The complexes exhibit phosphorescent emission with maxima around 600 nm, originating from triplet metal-to-ligand charge transfer states with partially mixed ligand-to-ligand charge transfer character. The emission is relatively long-lived, within the 200-400 ns range, and with quantum yields of 2-4%. The complexes were trialed as cellular markers in live HeLa cells, along with two previously reported rhenium tetrazolato complexes bound to unsubstituted 1,10-phenanthroline. All five complexes exhibit good cellular uptake and non-specific perinuclear localisation. Upon excitation at 405 nm, the emission from the rhenium complexes could be clearly distinguished from autofluorescence, as demonstrated by spectral detection within the live cells. Four of the complexes did not appear to be toxic, however prolonged excitation could result in membrane blebbing. No major sign of photobleaching was detected upon multiple imaging on the same cell sample.

New Synthesis Of Poly(1,3,4-Oxadiazoles)

NASA Technical Reports Server (NTRS)

Connell, John W.; Hergenrother, Paul M.; Wolf, Peter

1992-01-01

Synthesis via aromatic nucleophilic displacement yields new high-molecular-weight polymers. Polymers exhibited good mechanical and thermal properties. Synthetic route provided high-molecular-weight POX of new chemical structure, potentially more economical. Availability of large variety of activated aromatic dihalides, facilitates variation of chemical structures. Exhibit properties making them useful as films. Also useful in coatings, adhesives, moldings, and composites.

Between Exoticism and Universalism: Educational Sections in Latin American Participation at International Exhibitions, 1860-1900

ERIC Educational Resources Information Center

Dussel, Ines

2011-01-01

International exhibitions provide a good arena in which to study the circulation and transfer of educational ideas and practices in the second half of the nineteenth century. Structured around themes of industry, progress, and civilisation, and defined as ephemeral museums of the new world of commodities for the consumption of the masses, they…

Aminopropyl-functionalized ethane-bridged periodic mesoporous organosilica spheres: preparation and application in liquid chromatography.

PubMed

Li, Chun; Di, Bin; Hao, Weiqiang; Yan, Fang; Su, Mengxiang

2011-01-21

A synthetic approach for synthesizing spherical aminopropyl-functionalized ethane-bridged periodic mesoporous organosilicas (APEPMOs) is reported. The mesoporous material was prepared by a one-step co-condensation of 1,2-bis(triethoxysilyl)ethane (BTSE) and 3-aminopropyltriethoxysilane (APTES) using cetyltrimethylammonium chlorine (C(18)TACl) as a template with the aid of a co-solvent (methanol) in basic medium. The APEPMOs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), nitrogen sorption measurement, Fourier transform infrared spectroscopy (FT-IR) and elemental analysis. It was shown that this material exhibited spherical morphology, ordered cubic mesostructure and good mechanical strength. The APEPMOs were tested as a potential stationary phase for liquid chromatography (LC) because the column exhibited reduced back pressure. Moreover, they exhibited good chemical stability in basic mobile phase, which can be ascribed to the ethane groups in the mesoporous framework. Copyright © 2010 Elsevier B.V. All rights reserved.

Theoretical study of surface plasmon resonance sensors based on 2D bimetallic alloy grating

NASA Astrophysics Data System (ADS)

Dhibi, Abdelhak; Khemiri, Mehdi; Oumezzine, Mohamed

2016-11-01

A surface plasmon resonance (SPR) sensor based on 2D alloy grating with a high performance is proposed. The grating consists of homogeneous alloys of formula MxAg1-x, where M is gold, copper, platinum and palladium. Compared to the SPR sensors based a pure metal, the sensor based on angular interrogation with silver exhibits a sharper (i.e. larger depth-to-width ratio) reflectivity dip, which provides a big detection accuracy, whereas the sensor based on gold exhibits the broadest dips and the highest sensitivity. The detection accuracy of SPR sensor based a metal alloy is enhanced by the increase of silver composition. In addition, the composition of silver which is around 0.8 improves the sensitivity and the quality of SPR sensor of pure metal. Numerical simulations based on rigorous coupled wave analysis (RCWA) show that the sensor based on a metal alloy not only has a high sensitivity and a high detection accuracy, but also exhibits a good linearity and a good quality.

The effect of precipitants on Ni-Al2O3 catalysts prepared by a co-precipitation method for internal reforming in molten carbonate fuel cells

PubMed Central

Jung, You-Shick; Yoon, Wang-Lai; Seo, Yong-Seog; Rhee, Young-Woo

2012-01-01

Ni-Al2O3 catalysts are prepared via the co-precipitation method using various precipitants: urea, Na2CO3, NaOH, K2CO3, KOH and NH4OH. The effects of the precipitants on the physicochemical properties and catalytic activities of the Ni-Al2O3 catalysts are investigated. The Ni50-urea catalyst displays the largest specific surface area and the highest pore volume. This catalyst also exhibits the highest Ni dispersion and the largest Ni surface area. Ni50-urea catalyst prepared with urea as precipitant and Ni50-K2CO3 catalyst prepared with K2CO3 as precipitant exhibit high pore volumes and good catalytic activities for methane steam reforming. The Ni50-urea catalyst exhibits the best physicochemical properties and shows good catalytic activity and a strong resistance to electrolyte contamination. PMID:22962548

Synthesis and characterization of triazole based supramolecule for interaction with cefuroxime in tap water and blood plasma.

PubMed

Ahmed, Farid; Perveen, Samina; Shah, Kiramat; Shah, Muhammad Raza; Ahmed, Shakil

2018-01-01

In this study a new calix[4]arene triazole 5 was successfully synthesized using click reaction and characterized through UV-visible, FT-IR, 1 H NMR spectroscopes and Mass Spectrometry. The supramolecular interaction of compound 5 towards commonly used drugs has been carried out using UV-Visible spectroscopy. The supramolecule 5 showed characteristic enhancement in the absorbance intensity after mixing with Cefuroxime at pH (2-12). Compound 5 displayed considerably good interactions with cefuroxime in the presence of other drugs. Compound 5 exhibits linear relationship with cefuroxime concentration in the range of (10-80µM) with regression value of 0.9954. The standard deviation for 50µM Cefuroxime was found to be 0.01 and the limit of detection for cefuroxime was calculated to be 2µM. Job's plot experiments showed 1:1 (5: cefuroxime) binding stoichiometry between compound 5 and cefuroxime. Supramolecule 5 displayed fairly good spectrophotometric recognition of Cefuroxime in human blood plasma and tap water thus showing that the ingredients of tap water and plasma sample was inert in the recognition of cefuroxime. Copyright © 2017 Elsevier Inc. All rights reserved.

Enhanced microwave absorption properties of CTAB assisted Pr-Cu substituted nanomaterial

NASA Astrophysics Data System (ADS)

Sadiq, Imran; Naseem, Shahzad; Riaz, Saira; Khan, Hasan M.; Ashiq, Muhammad Naeem; Hussain, S. Sajjad; Rana, Mazhar

2016-09-01

In this study, the rare earth Pr3+and divalent Cu2+ elements substituted Sr1-xPrxMn2Fe16-yCuyO27 (x=0, 0.02, 0.06, 0.1 and y=0, 0.1, 0.3, 0.5) W-type hexagonal ferrites were prepared by Sol-Gel method. TGA and DSC analysis of as prepared material was carried out to confirm the temperature at which required phase can be obtained. The XRD patterns exhibit the single phase for all the samples and the lattice parameters were changed with the additives. The absorption bands at wave number 636 and 554 cm-1 in FTIR spectrum indicate the stretching vibration of metal-oxygen ions which also ratifies the single phase for the prepared material. Microstructural analysis confirms the agglomeration of nanograins which leads to formation of platelet like structure which cause in the enhancement of the microwave absorption properties of material. The minimum reflection loss of -59.8 dB at 9.34 GHz frequency was observed makes the prepared material good candidate to be used in super high frequency application. The attenuation constant and reflectivity results are also in good agreement with minimum reflection losses results.

Determination of Biogenic Amines in Seawater Using Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection.

PubMed

Gubartallah, Elbaleeq A; Makahleh, Ahmad; Quirino, Joselito P; Saad, Bahruddin

2018-05-08

A rapid and green analytical method based on capillary electrophoresis with capacitively coupled contactless conductivity detection (C⁴D) for the determination of eight environmental pollutants, the biogenic amines (putrescine, cadaverine, spermidine, spermine, tyramine, 2-phenylamine, histamine and tryptamine), is described. The separation was achieved under normal polarity mode at 24 °C and 25 kV with a hydrodynamic injection (50 mbar for 5 s) and using a bare fused-silica capillary (95 cm length × 50 µm i.d.) (detection length of 10.5 cm from the outlet end of the capillary). The optimized background electrolyte consisted of 400 mM malic acid. C⁴D parameters were set at a fixed amplitude (50 V) and frequency (600 kHz). Under the optimum conditions, the method exhibited good linearity over the range of 1.0⁻100 µg mL −1 ( R ² ≥ 0.981). The limits of detection based on signal to noise (S/N) ratios of 3 and 10 were ≤0.029 µg mL −1 . The method was used for the determination of seawater samples that were spiked with biogenic amines. Good recoveries (77⁻93%) were found.

Extraction and free radical scavenging activity of polysaccharide from 'Anji Baicha' (Camellia sinensis (L.) O. Kuntze).

PubMed

Zhang, Zhongshan; Wang, Xiaomei; Li, Jingfen; Wang, Guozhi; Mao, Genxiang

2016-03-01

In this study, the optimization of the extraction conditions of polysaccharide from 'Anji Baicha' (Camellia sinensis (L.) O. Kuntze) (AP) was investigated by response surface methodology (RSM). Three main independent variables (extraction temperature, time, ratio of water to raw material) were taken into consideration. And then the free radical scavenging activities of the sample were investigated including scavenging effects of superoxide and hydroxyl radicals. The RSM analysis showed good correspondence between experimental and predicted values.. The optimal condition to obtain the highest yield of AP was determined as follows: temperature 76.79 °C, time 2.48 h, ratio of water to material 22.53 mL/g. For the free radical scavenging activity, the IC50 values of Vc and AP were 7.78 and 83.25 μg/mL. And for the scavenging effect on hydroxyl radical, that of AP and Vc were 1.80 and 1.69 mg/mL. AP showed excellent antioxidant activity. This exhibited AP had a good potential for antioxidant. The purification and structure needs to be study in further. Copyright © 2015 Elsevier B.V. All rights reserved.

Hybrid molecularly imprinted polymers synthesized with 3-aminopropyltriethoxysilane-methacrylic acid monomer for miniaturized solid-phase extraction: A new and economical sample preparation strategy for determination of acyclovir in urine.

PubMed

Yan, Hongyuan; Wang, Mingyu; Han, Yehong; Qiao, Fengxia; Row, Kyung Ho

2014-06-13

The miniaturized molecularly imprinted solid-phase extraction (mini-MISPE) coupled with high-performance liquid chromatography was proposed for the determination of acyclovir in urine. 1.5-mL tapered plastic centrifuge tube filled with hybrid molecularly imprinted polymers (HMIPs) was used as the cartridge of mini-MISPE, and the HMIPs synthesized with 3-aminopropyltriethoxy silane-methacrylic acid as monomer exhibited good recognition and selectivity for acyclovir. Under the optimized condition, good linear calibration was obtained in a range of 0.5-15μgmL(-1) with the correlation coefficient of 0.9994, and the recoveries at three spiked levels were 91.6-103.3% in urine with the relative standard deviation (RSD) of ≤3.5%. Excellent intra-day and inter-day repeatability were achieved with RSD of ≤2.6% and 4.0% in three different concentrations. This method combined the advantages of HMIPs and mini-MISPE, and it could become an alternative tool for analyzing the residues of acyclovir in complex urine matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

Impact of Having a Mentally Disabled Child in the Family on the Oral Health of the Healthy Sibling: A Comparative Study.

PubMed

Chauhan, Astha; Nagarajappa, Sandesh; Dasar, Pralhad L; Mishra, Prashant

To determine and compare oral health status, knowledge and attitude among siblings of mentally disabled with siblings of normal healthy children. 240 study subjects consisting of 120 each of siblings of mentally disabled and normal, healthy children (control group) matched for age and gender were selected by convenience sampling. Oral health was assessed using the WHO-1997 proforma. A pretested questionnaire (30 items) was used for oral health knowledge and attitude assessment. Statistical analysis was performed using the chi-squared and Mann-Whitney tests. Caries prevalence among the siblings of mentally disabled and control group was 82% (mean DMFT 1.68 ± 1.18) and 45% (mean DMFT 0.58 ± 0.72), respectively (p < 0.05). The siblings of mentally disabled children also showed good oral health knowledge (mean 7.1 ± 1.4) and a positive attitude (p < 0.05). Siblings of mentally disabled children showed higher caries experience. Knowledge and attitude towards oral health was comparatively good among siblings of mentally disabled children. They exhibited favourable attitudes and involvement in helping their sibling to maintain oral health.

Suberin Fatty Acids from Outer Birch Bark: Isolation and Physical Material Characterization.

PubMed

Heinämäki, Jyrki; Pirttimaa, Minni M; Alakurtti, Sami; Pitkänen, H Pauliina; Kanerva, Heimo; Hulkko, Janne; Paaver, Urve; Aruväli, Jaan; Yliruusi, Jouko; Kogermann, Karin

2017-04-28

The isolation and physical material properties of suberin fatty acids (SFAs) were investigated with special reference to their potential applications as novel pharmaceutical excipients. SFAs were isolated from outer birch bark (OBB) with a new extractive hydrolysis method. The present simplified isolation process resulted in a moderate batch yield and chemical purity of SFAs, but further development is needed for establishing batch-to-batch variation. Cryogenic milling was the method of choice for the particle size reduction of SFAs powder. The cryogenically milled SFAs powder exhibited a semicrystalline structure with apparent microcrystalline domains within an amorphous fatty acids matrix. The thermogravimetric analysis (TGA) of SFAs samples showed a good thermal stability up to 200 °C, followed by a progressive weight loss, reaching a plateau at about 95% volatilization at about 470 °C. The binary blends of SFAs and microcrystalline cellulose (MCC; Avicel PH 101) in a ratio of 25:75 (w/w) displayed good powder flow and tablet compression properties. The corresponding theophylline-containing tablets showed sustained or prolonged-release characteristics. The physicochemical and bulk powder properties of SFAs isolated from OBB are auspicious in terms of potential pharmaceutical excipient applications.

Characterization and in vitro biocompatibility study of Ti-Si-N nanocomposite coatings developed by using physical vapor deposition

NASA Astrophysics Data System (ADS)

Trivedi, Pramanshu; gupta, Pallavi; Srivastava, Swati; Jayaganthan, R.; Chandra, Ramesh; Roy, Partha

2014-02-01

Amongst the Ti alloys used as orthopedic implant materials, Ti6Al4V is one of the widely used alloys. Magnetron sputtering was used to deposit nanocomposite coating of Ti-Si-N on the Ti6Al4V substrate at different power and then the coating structure and surface properties were characterized through contact angle measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). In vitro biocompatibility of the coatings was assessed by using mouse bone marrow mesenchymal stem cells (mBMMSC). Antibacterial studies were performed using Escherichia coli (E. coli) microorganisms. The osteogenic differentiation was also carried out in order to get gene expressions. The AFM results confirmed that the coatings deposited at 120 W was smoother as compared to other coatings developed at different power, along with optimum contact angle, also these coatings showed good antibacterial results. The fluorescent and viability results of 120 W sample confirmed their good biocompatibility as compared to the coatings deposited 20, 40, 60, and 100 W power. Hence, the coating deposited at 120 W exhibit desirable microstructural characteristics beneficial for surface modification of orthopedic implants.

Hard Carbon Originated from Polyvinyl Chloride Nanofibers As High-Performance Anode Material for Na-Ion Battery

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

Bai, Ying; Wang, Zhen; Wu, Chuan

2015-02-27

Two types of hard carbon materials were synthesized through direct pyrolysis of commercial polyvinyl chloride (PVC) particles and pyrolysis of PVC nanofibers at 600-800 degrees C, respectively, where the nanofibers were prepared by an electrospinning PVC precursors method. These as-prepared hard carbon samples were used as anode materials for Na-ion batteries. The hard carbon obtained from PVC nanofibers achieved a high reversible capacity of 271 mAh/g and an initial Coulombic efficiency of 69.9%, which were much superior to the one from commercial PVC, namely, a reversible capacity of 206 mAh/g and an initial Coulombic efficiency of 60.9%. In addition, themore » hard carbon originated from the PVC nanofibers exhibited good cycling stability and rate performance: the initial discharge capacities were 389, 228, 194, 178, 147 mAh/g at the current density of 12, 24, 60, 120, and 240 mA/g, respectively, retaining 211 mAh/g after 150 cycles. Such excellent cycle performance, high reversible capacity, and good rate capability enabled this hard carbon to be a promising candidate as anode material for Na-ion battery application.« less

Direct electrochemistry of glucose oxidase and biosensing for glucose based on carbon nanotubes@SnO(2)-Au composite.

PubMed

Li, Fenghua; Song, Jixia; Li, Fei; Wang, Xiaodan; Zhang, Qixian; Han, Dongxue; Ivaska, Ari; Niu, Li

2009-12-15

Multiwalled carbon nanotubes@SnO(2)-Au (MWCNTs@SnO(2)-Au) composite was synthesized by a chemical route. The structure and composition of the MWCNTs@SnO(2)-Au composite were confirmed by means of transmission electron microscopy, X-ray photoelectron and Raman spectroscopy. Due to the good electrocatalytic property of MWCNTs@SnO(2)-Au composite, a glucose biosensor was constructed by absorbing glucose oxidase (GOD) on the hybrid material. A direct electron transfer process is observed at the MWCNTs@SnO(2)-Au/GOD-modified glassy carbon electrode. The glucose biosensor has a linear range from 4.0 to 24.0mM, which is suitable for glucose determination by real samples. It should be worthwhile noting that, from 4.0 to 12.0mM, the cathodic peak currents of the biosensor decrease linearly with increasing the glucose concentrations in human blood. Meanwhile, the resulting biosensor can also prevent the effects of interfering species. Moreover, the biosensor exhibits satisfying reproducibility, good operational stability and storage stability. Therefore, the MWCNTs@SnO(2)-Au/GOD biocomposite could be promisingly applied to determine blood sugar concentration in the practical clinical analysis.

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.

High sensitivity and accuracy dissolved oxygen (DO) detection by using PtOEP/poly(MMA-co-TFEMA) sensing film.

PubMed

Zhang, Ke; Zhang, Honglin; Wang, Ying; Tian, Yanqing; Zhao, Jiupeng; Li, Yao

2017-01-05

Fluorinated acrylate polymer has received great interest in recent years due to its extraordinary characteristics such as high oxygen permeability, good stability, low surface energy and refractive index. In this work, platinum octaethylporphyrin/poly(methylmethacrylate-co-trifluoroethyl methacrylate) (PtOEP/poly(MMA-co-TFEMA)) oxygen sensing film was prepared by the immobilizing of PtOEP in a poly(MMA-co-TFEMA) matrix and the technological readiness of optical properties was established based on the principle of luminescence quenching. It was found that the oxygen-sensing performance could be improved by optimizing the monomer ratio (MMA/TFEMA=1:1), tributylphosphate(TBP, 0.05mL) and PtOEP (5μg) content. Under this condition, the maximum quenching ratio I0/I100 of the oxygen sensing film is obtained to be about 8.16, Stern-Volmer equation is I0/I=1.003+2.663[O2] (R(2)=0.999), exhibiting a linear relationship, good photo-stability, high sensitivity and accuracy. Finally, the synthesized PtOEP/poly(MMA-co-TFEMA) sensing film was used for DO detection in different water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

High sensitivity and accuracy dissolved oxygen (DO) detection by using PtOEP/poly(MMA-co-TFEMA) sensing film

NASA Astrophysics Data System (ADS)

Zhang, Ke; Zhang, Honglin; Wang, Ying; Tian, Yanqing; Zhao, Jiupeng; Li, Yao

2017-01-01

Fluorinated acrylate polymer has received great interest in recent years due to its extraordinary characteristics such as high oxygen permeability, good stability, low surface energy and refractive index. In this work, platinum octaethylporphyrin/poly(methylmethacrylate-co-trifluoroethyl methacrylate) (PtOEP/poly(MMA-co-TFEMA)) oxygen sensing film was prepared by the immobilizing of PtOEP in a poly(MMA-co-TFEMA) matrix and the technological readiness of optical properties was established based on the principle of luminescence quenching. It was found that the oxygen-sensing performance could be improved by optimizing the monomer ratio (MMA/TFEMA = 1:1), tributylphosphate(TBP, 0.05 mL) and PtOEP (5 μg) content. Under this condition, the maximum quenching ratio I0/I100 of the oxygen sensing film is obtained to be about 8.16, Stern-Volmer equation is I0/I = 1.003 + 2.663[O2] (R2 = 0.999), exhibiting a linear relationship, good photo-stability, high sensitivity and accuracy. Finally, the synthesized PtOEP/poly(MMA-co-TFEMA) sensing film was used for DO detection in different water samples.

Hard carbon originated from polyvinyl chloride nanofibers as high-performance anode material for Na-ion battery.

PubMed

Bai, Ying; Wang, Zhen; Wu, Chuan; Xu, Rui; Wu, Feng; Liu, Yuanchang; Li, Hui; Li, Yu; Lu, Jun; Amine, Khalil

2015-03-11

Two types of hard carbon materials were synthesized through direct pyrolysis of commercial polyvinyl chloride (PVC) particles and pyrolysis of PVC nanofibers at 600-800 °C, respectively, where the nanofibers were prepared by an electrospinning PVC precursors method. These as-prepared hard carbon samples were used as anode materials for Na-ion batteries. The hard carbon obtained from PVC nanofibers achieved a high reversible capacity of 271 mAh/g and an initial Coulombic efficiency of 69.9%, which were much superior to the one from commercial PVC, namely, a reversible capacity of 206 mAh/g and an initial Coulombic efficiency of 60.9%. In addition, the hard carbon originated from the PVC nanofibers exhibited good cycling stability and rate performance: the initial discharge capacities were 389, 228, 194, 178, 147 mAh/g at the current density of 12, 24, 60, 120, and 240 mA/g, respectively, retaining 211 mAh/g after 150 cycles. Such excellent cycle performance, high reversible capacity, and good rate capability enabled this hard carbon to be a promising candidate as anode material for Na-ion battery application.

Process development and characterization of centrosymmetric semiorganic nonlinear optical crystal: 4-dimethylaminopyridine potassium chloride

NASA Astrophysics Data System (ADS)

Johnson, J.; Srineevasan, R.; Sivavishnu, D.

2018-06-01

Centrosymmetric semiorganic crystal 4-dimethylaminopyridine potassium chloride (4-DMAPKC) has been grown successfully by using slow evaporation solution growth technique. Powder x-ray diffraction shows the 4-DMAPKC crystal has good crystalline nature. Single crystal XRD shows that the grown 4-DMAPKC is cubic crystal system with cell parameters a = 3.09 Å, b = 3.09 Å, c = 3.09 Å. Investigation has been carried out to assign the Vibrational frequencies of the grown crystal by FTIR spectral studies. UVsbnd Visible NIR optical absorption spectral studies in the range of 200-1100 nm shows low absorption in UVsbnd Visible region with lower cutoff wave length at 261 nm and optical band gap energy was found as Eg = 5.52 eV. Optically transmittance spectral shows 4-DMAPKC crystal is very good transparency in UV-Visible NIR region. Thermogravimetry and differential thermal (TG-DTA) analysis were carried out. Dielectric studies of as grown crystal sample exhibit low dielectric constant and loss at higher frequencies and attests the nonlinear optical activity. Micro hardness studies of as grown crystal were discussed. Second harmonic generation (SHG) efficiency of the 4-DMAPKC is 0.69 times as that of KDP.

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.

Potent and Selective Amidopyrazole Inhibitors of IRAK4 That Are Efficacious in a Rodent Model of Inflammation

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

McElroy, William T.; Tan, Zheng; Ho, Ginny

IRAK4 is a critical upstream kinase in the IL-1R/TLR signaling pathway. Inhibition of IRAK4 is hypothesized to be beneficial in the treatment of autoimmune related disorders. A screening campaign identified a pyrazole class of IRAK4 inhibitors that were determined by X-ray crystallography to exhibit an unusual binding mode. SAR efforts focused on the identification of a potent and selective inhibitor with good aqueous solubility and rodent pharmacokinetics. Pyrazole C-3 piperidines were well tolerated, with N-sulfonyl analogues generally having good rodent oral exposure but poor solubility. N-Alkyl piperidines exhibited excellent solubility and reduced exposure. Pyrazoles possessing N-1 pyridine and fluorophenyl substituentsmore » were among the most active. Piperazine 32 was a potent enzyme inhibitor with good cellular activity. Compound 32 reduced the in vivo production of proinflammatory cytokines and was orally efficacious in a mouse antibody induced arthritis disease model of inflammation.« less

Aesthetic properties and message customization: navigating the dark side of web recruitment.

PubMed

Dineen, Brian R; Ling, Juan; Ash, Steven R; DelVecchio, Devon

2007-03-01

The authors examined recruitment message viewing time, information recall, and attraction in a Web-based context. In particular, they extended theory related to the cognitive processing of recruitment messages and found that the provision of customized information about likely fit related to increased viewing time and recall when good aesthetics were also present. A 3-way interaction among moderate-to low-fitting individuals further indicated that objective fit was most strongly related to attraction when messages included both good aesthetics and customized information. In particular, given this combination, the poorest fitting individuals exhibited lower attraction levels, whereas more moderately fitting individuals exhibited invariant attraction levels across combinations of aesthetics and customized information. The results suggest that, given good aesthetics, customized information exerts effects mostly by causing poorly fitting individuals to be less attracted, which further suggests a means of averting the "dark side" of Web recruitment that occurs when organizations receive too many applications from poorly fitting applicants. (c) 2007 APA, all rights reserved.

A Diastereoselective Multicomponent Reaction for Construction of Alkynylamide-Substituted α,β-Diamino Acid Derivatives To Hunt Hits.

PubMed

Lei, Ruirui; Wu, Yong; Dong, Suzhen; Jia, Kaili; Liu, Shunying; Hu, Wenhao

2017-03-17

A highly diasetereoselective Mannich-type multicomponent reaction was developed to rapidly construct alkynylamide-substituted α,β-diamino acid derivatives from simple starting materials under mild conditions in moderate to good yields for hit hunting. Most of the resulting products 4 exhibited good anticancer activity in HCT116, BEL7402, and SMMC7721 cells.

Facile solvothermal synthesis of cube-like Ag@AgCl: a highly efficient visible light photocatalyst

NASA Astrophysics Data System (ADS)

Han, Lei; Wang, Ping; Zhu, Chengzhou; Zhai, Yueming; Dong, Shaojun

2011-07-01

In this paper, a stable and highly efficient plasmonic photocatalyst, Ag@AgCl, with cube-like morphology, has been successfully prepared via a simple hydrothermal method. Using methylene dichloride as chlorine source in the synthesis can efficiently control the morphology of Ag@AgCl, due to the low release rate of chloride ions. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra were used to characterize the obtained product. The photocatalytic activity of the obtained product was evaluated by the photodegradation of methyl orange (MO) under visible light irradiation, and it was found, interestingly, that Ag@AgCl exhibits high visible light photocatalytic activity and good stability.In this paper, a stable and highly efficient plasmonic photocatalyst, Ag@AgCl, with cube-like morphology, has been successfully prepared via a simple hydrothermal method. Using methylene dichloride as chlorine source in the synthesis can efficiently control the morphology of Ag@AgCl, due to the low release rate of chloride ions. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra were used to characterize the obtained product. The photocatalytic activity of the obtained product was evaluated by the photodegradation of methyl orange (MO) under visible light irradiation, and it was found, interestingly, that Ag@AgCl exhibits high visible light photocatalytic activity and good stability. Electronic supplementary information (ESI) available: SEM images of the AgCl samples synthesized by changing the addition amount of PVP and AgNO3. See DOI: 10.1039/c1nr10247h

A novel electrochemical sensor based on Cu3P@NH2-MIL-125(Ti) nanocomposite for efficient electrocatalytic oxidation and sensitive detection of hydrazine

NASA Astrophysics Data System (ADS)

Wang, Minghua; Yang, Longyu; Hu, Bin; Liu, Yongkang; Song, Yingpan; He, Linghao; Zhang, Zhihong; Fang, Shaoming

2018-07-01

A novel electrocatalyst based on amine-functionalized Ti-based metal-organic framework (NH2-MIL-125(Ti)) embedded with Cu3P nanocrystals (denoted by Cu3P@NH2-MIL-125(Ti)) was synthesized and used for electrocatalytic oxidation and detection of hydrazine in aqueous solution. A series of Cu3P@NH2-MIL-125(Ti) nanocomposites were obtained by adding Cu3P nanoparticles into the preparation system of NH2-MIL-125(Ti), with the Cu3P nanocrystals derived from the phospatization of Cu(OH)2 at high temperature. Based on the detailed characterizations and analysis of the chemical and physical performances of the series of Cu3P@NH2-MIL-125(Ti) nanocomposites at dosages of Cu3P nanocrystals at 5, 20, 50, and 100 mg, the good synergic effect between the Cu3P (50 mg) and the NH2-MIL-125(Ti) endows the as-prepared Cu3P50@NH2-MIL-125(Ti) nanocomposite with the excellent electrocatalytic activity toward the electrocatalytic oxidation of hydrazine. The Cu3P50@NH2-MIL-125(Ti)-based electrochemical sensor exhibited a detection limit of 79 nM (S/N = 3) within a wider linear range from 5 μM to 7.5 mM. Moreover, the developed sensor exhibited high selectivity toward the detection of hydrazine with the addition of certain common interferents and good applicability in real samples. All of these results imply that the Cu3P50@NH2-MIL-125(Ti) nanocomposite could be promising for detecting hydrazine and offer potential applications in the field of electroanalytical chemistry.

Balsam-Pear-Skin-Like Porous Polyacrylonitrile Nanofibrous Membranes Grafted with Polyethyleneimine for Postcombustion CO2 Capture.

PubMed

Zhang, Yufei; Guan, Jiming; Wang, Xianfeng; Yu, Jianyong; Ding, Bin

2017-11-22

Amine-containing sorbents have been extensively studied for postcombustion carbon dioxide (CO 2 ) capture because of their ability to chemisorb CO 2 from the flue gas. However, most sorbents are in the form of powders currently, which is not the ideal configuration for the flue gas separation because of the fragile nature and poor mechanical properties, resulting in blocking of the flow pipes and difficult recycling. Herein, we present a novel approach for the facile fabrication of flexible, robust, and polyethyleneimine-grafted (PEI-grafted) hydrolyzed porous PAN nanofibrous membranes (HPPAN-PEI NFMs) through the combination of electrospinning, pore-forming process, hydrolysis reaction, and the subsequent grafting technique. Excitingly, we find that all the resultant porous PAN (PPAN) fibers exhibit a balsam-pear-skin-like porous structure due to the selective removal of poly(vinylpyrrolidone) (PVP) from PAN/PVP fibers by water extraction. Significantly, the HPPAN-PEI NFMs retain their mesoporosity, as well as exhibit good thermal stability and prominent tensile strength (11.1 MPa) after grafting, guaranteeing their application in CO 2 trapping from the flue gas. When exposed to CO 2 at 40 °C, the HPPAN-PEI NFMs show an enhanced CO 2 adsorption capacity of 1.23 mmol g -1 (based on the overall quantity of the sample) or 6.15 mmol g -1 (based on the quantity of grafted PEI). Moreover, the developed HPPAN-PEI NFMs display significantly selective capture for CO 2 over N 2 and excellent recyclability. The CO 2 capacity retains 92% of the initial value after 20 adsorption-desorption cycle tests, indicating that the resultant HPPAN-PEI NFMs have good long-term stability. This work paves the way for fabricating NFM-based solid adsorption materials endowed with a porous structure applied to efficient postcombustion CO 2 capture.

Ultrasensitive sandwich-type electrochemical immunosensor based on a novel signal amplification strategy using highly loaded palladium nanoparticles/carbon decorated magnetic microspheres as signal labels.

PubMed

Ji, Lei; Guo, Zhankui; Yan, Tao; Ma, Hongmin; Du, Bin; Li, Yueyun; Wei, Qin

2015-06-15

An ultrasensitive sandwich-type electrochemical immunosensor for quantitative detection of alpha fetoprotein (AFP) was proposed based on a novel signal amplification strategy in this work. Carbon decorated Fe3O4 magnetic microspheres (Fe3O4@C) with large specific surface area and good adsorption property were used as labels to anchor palladium nanoparticles (Pd NPs) and the secondary antibodies (Ab2). Pd NPs were loaded on Fe3O4@C to obtain Fe3O4@C@Pd with core-shell structure by electrostatic attraction, which were further used to immobilize Ab2 due to the bonding of Pd-NH2. A signal amplification strategy was the noble metal nanoparticles, such as Pd NPs, exhibiting high electrocatalytic activities toward hydrogen peroxide (H2O2) reduction. This signal amplification was novel not only because of the great capacity, but also the ease of magnetic separation from the sample solution based on their magnetic property. Moreover, carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) were used for the immobilization of primary antibodies (Ab1). Therefore, high sensitivity could be realized by the designed immunosensor based on this novel signal amplification strategy. Under optimal conditions, the immunosensor exhibited a wide linear range of 0.5 pg/mL to 10 ng/mL toward AFP with a detection limit of 0.16 pg/mL (S/N=3). Moreover, it revealed good selectivity, acceptable reproducibility and stability, indicating a potential application in clinical monitoring of tumor biomarkers. Copyright © 2015 Elsevier B.V. All rights reserved.

Insufficient quality of sputum submitted for tuberculosis diagnosis and associated factors, in Klaten district, Indonesia

PubMed Central

Sakundarno, Mateus; Nurjazuli, Nurjazuli; Jati, Sutopo Patria; Sariningdyah, Retna; Purwadi, Sumarsono; Alisjahbana, Bachti; van der Werf, Marieke J

2009-01-01

Background Sputum smear microscopy is the standard diagnostic method for detection of smear positive pulmonary tuberculosis (TB). Insufficient quality of sputum might result in missing cases. In this study we aimed at assessing the quality of sputum in a district in Central Java and determining patient and health worker factors associated with submission of three good quality sputum samples. Methods In 16 health centers information was collected on the quality of sputum submitted by TB suspects, i.e. volume, color, and viscosity. TB suspects were interviewed to assess their knowledge of TB, motivation to provide sputum and whether they were informed why and how to produce a sputum sample. Health workers were interviewed to assess what information they provided to TB suspects about the reason for sputum examination, methods to produce sputum and characteristics of a good quality sputum sample. All health worker and patient factors were evaluated for association with sputum quality. Results Of 387 TB suspects, 294 (76.0%) could be traced and interviewed, and of 272 (70.3%) information about sputum quality was available. Of those 203 (74.6%) submitted three samples, 90 (33.1%) provided at least one good sample, and 37 (13.6%) provided three good quality sputum samples. Of the 272 TB suspects, 168 (61.8%) mentioned that information on the reason for sputum examination was provided, 66 (24.3%) remembered that they were informed about how to produce sputum and 40 (14.7%) recalled being informed about the characteristics of good quality sputum. Paramedics reported to provide often/always information on the importance of sputum examination, and when to produce sputum. Information on how to produce sputum and characteristics of a good sputum sample was less often provided. None of the studied patient characteristics or health worker factors was associated with providing good quality sputum. Conclusion A considerable number of TB suspects did not provide three sputum samples and a large number of sputum samples were of insufficient quality. Training of health workers in providing health education to the TB suspect about the reason for sputum examination and how to produce a good quality sputum sample should be a priority of the TB program. PMID:19426477

Ratiometric fluorescent detection of chromium(VI) in real samples based on dual emissive carbon dots.

PubMed

Ma, Yunxia; Chen, Yonglei; Liu, Juanjuan; Han, Yangxia; Ma, Sudai; Chen, Xingguo

2018-08-01

As we know, hexavalent chromium (Cr(VI)) was usually used as an additive to improve the color fastness during the printing and dyeing process, and thus posing tremendous threat to our health and living quality. In this work, the dual emissive carbon dots (DECDs) were synthesized through hydrothermal treatment of m-aminophenol and oxalic acid. The obtained DECDs not only exhibited dual emission fluorescence peaks (430 nm, 510 nm) under the single excitation wavelength of 380 nm, but also possessed good water solubility and excellent fluorescence stability. A ratiometric fluorescent method for the determination of Cr(VI) was developed using the DECDs as a probe. Under the optimal conditions, a linear range was obtained from 2 to 300 μM with a limit of detection of 0.4 μM. Furthermore, the proposed ratiometric fluorescent method was applied to the analysis of Cr(VI) in textile, steel, industrial wastewater and chromium residue samples with satisfactory recoveries (88.4-106.8%). Copyright © 2018 Elsevier B.V. All rights reserved.

In situ synthesis of TiO2/polyethylene terephthalate hybrid nanocomposites at low temperature

NASA Astrophysics Data System (ADS)

Peng, Xinyan; Ding, Enyong; Xue, Feng

2012-06-01

TiO2 nanoflowers were in situ grown on polyethylene terephthalate (PET) non-woven fabric by hydrolysis of TiCl4 in aqueous solution in the presence of nanocrystal cellulose grafted PET fabric (NCC-g-PET) at a low temperature of 70 °C. Nanocrystal cellulose (NCC) pre-grafted on PET fabric acted as hydrophilic substrate and morphology inducing agent to promote the nucleation and crystal growth of TiO2. Detailed information on the synthetic process was presented. The resulting samples were characterized using FE-SEM, EDS, ATR-IR, Raman microscopy, XRD and TG analysis. The photocatalytic activity of the samples was evaluated by the degradation of orange methyl under solar light. Characteristic results indicate that rutile TiO2 nanoflowers have grown abundantly on PET non-woven fabric, and the established hydrogen bonding strengthens the interfacial interaction between the inorganic particles and the polymeric substrates. The methyl orange decoloration test under natural solar light demonstrates that this TiO2/PET hybrid nanocomposites exhibit excellent self-cleaning performance which is expected to have a good potential for commercialization.

Raman Excitation Profile of the G-band Enhancement in Twisted Bilayer Graphene

NASA Astrophysics Data System (ADS)

Eliel, G. S. N.; Ribeiro, H. B.; Sato, K.; Saito, R.; Lu, Chun-Chieh; Chiu, Po-Wen; Fantini, C.; Righi, A.; Pimenta, M. A.

2017-12-01

A resonant Raman study of twisted bilayer graphene (TBG) samples with different twisting angles using many different laser lines in the visible range is presented. The samples were fabricated by CVD technique and transferred to Si/SiO2 substrates. The Raman excitation profiles of the huge enhancement of the G-band intensity for a group of different TBG flakes were obtained experimentally, and the analysis of the profiles using a theoretical expression for the Raman intensities allowed us to obtain the energies of the van Hove singularities generated by the Moiré patterns and the lifetimes of the excited state of the Raman process. Our results exhibit a good agreement between experimental and calculated energies for van Hove singularities and show that the lifetime of photoexcited carrier does not depend significantly on the twisting angle in the range intermediate angles ( 𝜃 between 10∘ and 15∘). We observed that the width of the resonance window (Γ ≈ 250 meV) is much larger than the REP of the Raman modes of carbon nanotubes, which are also enhanced by resonances with van Hove singularities.

Wire Arc Additive Manufacturing of AZ31 Magnesium Alloy: Grain Refinement by Adjusting Pulse Frequency.

PubMed

Guo, Jing; Zhou, Yong; Liu, Changmeng; Wu, Qianru; Chen, Xianping; Lu, Jiping

2016-10-09

Wire arc additive manufacturing (WAAM) offers a potential approach to fabricate large-scale magnesium alloy components with low cost and high efficiency, although this topic is yet to be reported in literature. In this study, WAAM is preliminarily applied to fabricate AZ31 magnesium. Fully dense AZ31 magnesium alloy components are successfully obtained. Meanwhile, to refine grains and obtain good mechanical properties, the effects of pulse frequency (1, 2, 5, 10, 100, and 500 Hz) on the macrostructure, microstructure and tensile properties are investigated. The results indicate that pulse frequency can result in the change of weld pool oscillations and cooling rate. This further leads to the change of the grain size, grain shape, as well as the tensile properties. Meanwhile, due to the resonance of the weld pool at 5 Hz and 10 Hz, the samples have poor geometry accuracy but contain finer equiaxed grains (21 μm) and exhibit higher ultimate tensile strength (260 MPa) and yield strength (102 MPa), which are similar to those of the forged AZ31 alloy. Moreover, the elongation of all samples is above 23%.

Fabrication of chitosan/polyacrylonitrile blend and semi-IPN hydrogel with epichlorohydrin

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

Aijaz, Muhammad Omer; Haider, Sajjad, E-mail: shaider@ksu.edu.sa; Al Mubddel, Fahad S.

2015-05-22

The present study is focused on the preparation of chitosan (CS)/polyacrylonitrile (PAN) blend and semi-interpenetrating polymer network (sIPN). Blend CS/PAN hydrogel films (HFs) were prepared by solution blending and casting technique. CS in the blend was crosslinked with epichlorohydrin (ECH) to prepare sIPN. The developed CS/PAN blend and sIPN hydrogels were characterized with Field Emission Scanning Electron Microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), Thermagravimetric analysis (TGA), and Differential Scanning Calorimeter (DSC). The result showed good miscibility between CS and PAN and crosslinking of CS in the blend. The swelling of the different blended and sIPN hydrogels samples were examinedmore » at room temperature (T{sub r}). Blend (C80/P20) sample showed highest swelling (∼2400%) and fair degree of stability (∼28% until 96 h), whereas sIPN hydrogel exhibited relatively low degree of swelling (∼244%) and high degree of aqueous (∼85 % until 96 h), and thermal (onset temperature 304°C) stabilities.« less

The Lyophilization Process Maintains the Chemical and Biological Characteristics of Royal Jelly

PubMed Central

Moraes, Larissa Ariana Roveroni; Ferreira, Nathália Ursoli; Moreno, Gabriela de Padua; Uahib, Fernanda Grassi Mangolini; Barizon, Edna Aparecida

2015-01-01

The alternative use of natural products, like royal jelly (RJ), may be an important tool for the treatment of infections caused by antibiotic-resistant bacteria. RJ presents a large number of bioactive substances, including antimicrobial compounds. In this study, we carried out the chemical characterization of fresh and lyophilized RJ and investigated their antibacterial effects with the purpose of evaluating if the lyophilization process maintains the chemical and antibacterial properties of RJ. Furthermore, we evaluated the antibacterial efficacy of the main fatty acid found in RJ, the 10-hydroxy-2-decenoic acid (10H2DA). Chromatographic profile of the RJ samples showed similar fingerprints and the presence of 10H2DA in both samples. Furthermore, fresh and lyophilized RJ were effective against all bacteria evaluated; that is, the lyophilization process maintains the antibacterial activity of RJ and the chemical field of 10H2DA. The fatty acid 10H2DA exhibited a good antibacterial activity against Streptococcus pneumoniae. Therefore, it may be used as an alternative and complementary treatment for infections caused by antibiotic-resistant S. pneumoniae. PMID:26064175

In-gas-cell laser ionization studies of plutonium isotopes at IGISOL

NASA Astrophysics Data System (ADS)

Pohjalainen, I.; Moore, I. D.; Kron, T.; Raeder, S.; Sonnenschein, V.; Tomita, H.; Trautmann, N.; Voss, A.; Wendt, K.

2016-06-01

In-gas-cell resonance laser ionization has been performed on long-lived isotopes of Pu at the IGISOL facility, Jyväskylä. This initiates a new programme of research towards high-resolution optical spectroscopy of heavy actinide elements which can be produced in sufficient quantities at research reactors and transported to facilities elsewhere. In this work a new gas cell has been constructed for fast extraction of laser-ionized elements. Samples of 238-240,242Pu and 244Pu have been evaporated from Ta filaments, laser ionized, mass separated and delivered to the collinear laser spectroscopy station. Here we report on the performance of the gas cell through studies of the mass spectra obtained in helium and argon, before and after the radiofrequency quadrupole cooler-buncher. This provides valuable insight into the gas phase chemistry exhibited by Pu, which has been additionally supported by measurements of ion time profiles. The resulting monoatomic yields are sufficient for collinear laser spectroscopy. A gamma-ray spectroscopic analysis of the Pu samples shows a good agreement with the assay provided by the Mainz Nuclear Chemistry department.

Cellulosic fabrics printing with multifunctional encapsulated phthalocyanine pigment blue using phase separation method.

PubMed

Haroun, Ahmed A; Diab, H A; Hakeim, O A

2016-08-01

Aqueous dispersions of citric-acrylate (CAC) oligomer encapsulating C.I. Pigment Blue 15:3 (PB15:3) in the presence of glutaraldhyde were formulated using the phase separation method. FT-IR spectroscopy and centrifuge sedimentation are performed to confirm the encapsulation of pigment into CAC oligomer. The prepared capsules were characterized using thermal gravimetric analysis (TGA) and transmission electron microscope (TEM). The results revealed that the encapsulated pigment had a profound multifunctional impact and minimized the driving force of pigment printing on the cellulosic fabrics. Besides, the encapsulated pigment accelerated the pigment fixation on cellulosic fabrics without drying in one step and reduced the required amount of the binder, compared with the control sample. Furthermore, the printed fabrics exhibited good antibacterial performance against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The presence of the crosslinker could be stabilized the encapsulated pigment on the cellulosic fabrics. Moreover, the light and washing fastness for the printed fabrics using encapsulated pigment are higher than that in case of using control samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microleakage and antibacterial properties of ZnO and ZnO:Ag nanopowders prepared via a sol-gel method for endodontic sealer application

NASA Astrophysics Data System (ADS)

Shayani Rad, M.; Kompany, A.; Khorsand Zak, A.; Javidi, M.; Mortazavi, S. M.

2013-09-01

One of the most important problems in dentistry is the microleakage, whether apical or coronal, which may cause failure of root canal therapy. The aim of this study is to prepare suitable sealer to decrease the microleakage of the root canals as well as having good antibacterial property. Pure ZnO and ZnO:Ag nanopowders were synthesized via sol gel method using gelatin as polymerization agent calcined at different temperatures of 500, 600, and 700 °C for 8 h. The prepared samples were characterized using X-ray diffraction and transition electron microscopy. The microleakage and antibacterial properties of the prepared samples were investigated and compared with zinc oxide eugenol (ZOE) and epoxy resin sealer (AH26), which are commonly used in dentistry as sealers. The results showed that the synthesized pure ZnO and ZnO:Ag nanopowders exhibit better microleakage and antibacterial properties in comparison with ZOE and AH26 sealers, and therefore are more suitable filling materials to be used as sealer in root canal treatment.

High-temperature catalytically assisted combustion. Final report, 1 August 1981-31 July 1983

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

Bracco, F.V.; Royce, B.S.H.; Santavicca, D.A.

1983-07-31

Results of research on a two-dimensional, transient catalytic combustion model and on a high temperature perovskite catalyst are presented. A recently developed two-dimensional, transient model was used to study the ignition of carbon monoxide/air mixtures in a platinum-coated catalytic honeycomb. Comparisons between calculated and measured steady-state substrate temperature profiles and exhaust-gas compositions show good agreement. A platinum-doped perovskite catalyst proposed will exhibit low-temperature light off and high-temperature stability. Preliminary tests using a perovskite powder with 1 wt.% platinium are encouraging, showing very little change in surface activity when used with propane fuel. Variations in catalytic activity from sample to samplemore » were also found, and after extensive testing the cause of these variations could not be identified. However, preliminary tests using Fourier-transform infrared photoacoustic spectroscopy do indicate differences in the various catalyst samples that may be related to the difference in catalytic activity. The use of bench-top-oven and differential-scanning-calorimetry techniques for screening catalysts in terms of relative activity and aging characteristics were also demonstrated.« less

Synthesis of a novel molecularly imprinted organic-inorganic hybrid polymer for the selective isolation and determination of fluoroquinolones in tilapia.

PubMed

Yang, Xun; Wang, Ruiling; Wang, Weihua; Yan, Hongyuan; Qiu, Mande; Song, Yanxue

2014-01-15

A novel molecularly imprinted organic-inorganic hybrid polymer (MI-MAA/APTS) based on a dummy molecular imprinting technique and an organic-inorganic hybrid material technique was synthesised and used as a sorbent in solid-phase extraction for the selective isolation and determination of ofloxacin (OFL), lomefloxacin (LOM), and ciprofloxacin (CIP) in tilapia samples. The MI-MAA/APTS sorbent was prepared from 3-aminopropyltriethoxysilanes (APTS) as an inorganic source and methacrylic acid (MAA) as an organic source and exhibited high mechanical strength and special affinities to the analytes. A comparison of MI-MAA/APTS with other conventional sorbents (C18 and HLB) showed that MI-MAA/APTS displayed good selectivity and affinity for OFL, LOM, and CIP, and the recoveries of the analytes at three spiked levels were in the range of 85.1-101.0%, with the relative standard deviations ≤5.1%. The presented MI-MAA/APTS-SPE-HPLC method could be potentially applied to the determination of fluoroquinolones (FQs) in complex fish samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis of phenolic acids by ionic liquid-in-water microemulsion liquid chromatography coupled with ultraviolet and electrochemical detector.

PubMed

Peng, Li-Qing; Cao, Jun; Du, Li-Jing; Zhang, Qi-Dong; Shi, Yu-Tin; Xu, Jing-Jing

2017-05-26

An environmentally friendly ionic liquid-in-water (IL/W) microemulsion was established and applied as mobile phase in microemulsion liquid chromatography (MELC) with ultraviolet (UV) detection or electrochemical detector (ECD) for analysis of phenolic compounds in real samples. The optimal condition of the method was using the best composition of microemulsion (0.2% w/v [HMIM]PF 6 , 1.0% w/v SDS, 3.0% w/v n-butanol, 95.8% v/v water, pH 2.5) with UV detection. The validation results indicated that the method provided high degree of sensitivity, precision and accuracy with the low limit of detections ranged from 17.9-238ng/mL, satisfactory mean recovery values in the range of 80.1-105% and good linearity (r 2 >0.9994). Additionally, this method exhibited high selectivity and resolution for the analytes and was more eco-friendly compared with traditional MELC method. Consequently, the established IL/W MELC method was successfully applied to simultaneously separate and determine target compounds in Danshen sample and its preparation. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and electrochemical properties of layered structure Li[Ni{sub 0.5}Co{sub 0.25}Mn{sub 0.25}]O{sub 2} cathode material

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

Prathibha, G.; Rosaiah, P.; Reddy, B. Purusottam

Lithium ion (Li-ion) batteries are currently the energy source of choice for cell phones, laptops, and other mobile electronic devices due to their balance of high energy density with high power density compared to other electrochemical energy carriers. In the present study, mixed hydroxide method is used to prepare Li[Ni{sub 0.5}Co{sub 0.25}Mn{sub 0.25}]O{sub 2} from the precursors and analyze qualitatively and studied the electrochemical properties. The XRD spectrum exhibited predominant (003) orientation at 2θ =18.39{sup o} corresponding to hexagonal layered structure of R3m symmetry with evaluated lattice parameters are a= 2.84 Å, c= 14.43 Å. Raman measurements were performed tomore » understand the microstructure and vibrational modes of the prepared sample. From the electrochemical (EC) studies an initial discharge capacity of about 140 mAhg{sup −1} with good cyclic stability was observed for the prepared sample in the potential range 0.0 −1.0V in aqueous medium.« less

Molecularly imprinted solid-phase extraction for the determination of ten macrolide drugs residues in animal muscles by liquid chromatography-tandem mass spectrometry.

PubMed

Song, Xuqin; Zhou, Tong; Liu, Qingying; Zhang, Meiyu; Meng, Chenying; Li, Jiufeng; He, Limin

2016-10-01

A simple and sensitive method based on molecularly imprinted solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry was developed for the determination of the residues of ten macrolide drugs in swine, cattle and chicken muscles samples. The molecularly imprinted polymers (MIPs) were synthesized using tylosin as a template and methacrylic acid as a functional monomer. Samples were extracted with sodium borate buffer solution and ethyl acetate, and purified by the MIP cartridge. The results showed that the cartridge exhibited good recognition performance for macrolides, and better purification effect than the traditional solid-phase extraction cartridges. Recoveries of analytes at three spiking levels 1, 5 and 20μgkg(-1) ranged from 60.7% to 100.3% with the relative standard deviations less than 14%. The limits of detection of the method were between 0.1 and 0.4μgkg(-1). The method is useful for the routine monitoring of the residues of macrolide drugs in animal muscles. Copyright © 2016 Elsevier Ltd. All rights reserved.

PEG-template for surface modification of zeolite: A convenient material to the design of polypropylene based composite for packaging films

NASA Astrophysics Data System (ADS)

Toommee, S.; Pratumpong, P.

2018-06-01

Zeolite was successfully modified by conventional synthetic route. Polyethylene glycol was employed for surface modification of zeolite. The surface of zeolite exhibited therefore hydrophobic properties. Less than 5 wt% of modified zeolites with uniform size and shape were integrated into polypropylene matrix. Mechanical properties of composite exhibited the similar trend compare to neat polypropylene. Oxygen transmission rate and water vapor transmission rate were evaluated and it exhibited the strong potential to be a good candidate material in active packaging.

Fuzzy controller training using particle swarm optimization for nonlinear system control.

PubMed

Karakuzu, Cihan

2008-04-01

This paper proposes and describes an effective utilization of particle swarm optimization (PSO) to train a Takagi-Sugeno (TS)-type fuzzy controller. Performance evaluation of the proposed fuzzy training method using the obtained simulation results is provided with two samples of highly nonlinear systems: a continuous stirred tank reactor (CSTR) and a Van der Pol (VDP) oscillator. The superiority of the proposed learning technique is that there is no need for a partial derivative with respect to the parameter for learning. This fuzzy learning technique is suitable for real-time implementation, especially if the system model is unknown and a supervised training cannot be run. In this study, all parameters of the controller are optimized with PSO in order to prove that a fuzzy controller trained by PSO exhibits a good control performance.

Improved characteristics of amorphous indium-gallium-zinc-oxide-based resistive random access memory using hydrogen post-annealing

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

Kang, Dae Yun; Lee, Tae-Ho; Kim, Tae Geun, E-mail: tgkim1@korea.ac.kr

The authors report an improvement in resistive switching (RS) characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO)-based resistive random access memory devices using hydrogen post-annealing. Because this a-IGZO thin film has oxygen off-stoichiometry in the form of deficient and excessive oxygen sites, the film properties can be improved by introducing hydrogen atoms through the annealing process. After hydrogen post-annealing, the device exhibited a stable bipolar RS, low-voltage set and reset operation, long retention (>10{sup 5 }s), good endurance (>10{sup 6} cycles), and a narrow distribution in each current state. The effect of hydrogen post-annealing is also investigated by analyzing the sample surface using X-raymore » photon spectroscopy and atomic force microscopy.« less

High-frequency fluctuations in Denmark Strait transport

NASA Astrophysics Data System (ADS)

Haine, T. W. N.

2010-07-01

Denmark Strait ocean current transport exhibits quasi-regular fluctuations immediately south of the sill with periods of 2-4 days. The transport variability is similar to the mean transport itself. Using a circulation model we explore prospects to monitor the fluctuations. The model has realistic transport and shows water leaving Denmark Strait in equivalent-barotropic cyclones that are nearly geostrophic and correlate with sea-surface height (SSH). Existing satellite altimeter observations of SSH have adequate space/time sampling to reconstruct the transport fluctuations using a regression developed from the model results, but measurement error overwhelms the signal. From the model results, the pending Surface Water and Ocean Topography (SWOT) wide-swath altimeter appears accurate enough, and with good-enough coverage, to allow the transport fluctuations to be reconstructed. Bottom pressure recorders at the exit of the Denmark Strait can also reproduce the transport variability.

Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Xie, Yi; Heo, Sung Hwan; Yoo, Seung Hwa; Ali, Ghafar; Cho, Sung Oh

2010-03-01

A simple and straightforward approach to prepare TiO2-coated carbon nanotubes (CNTs) is presented. Anatase TiO2 nanoparticles (NPs) with the average size ~8 nm were coated on CNTs from peroxo titanic acid (PTA) precursor even at low temperature of 100 °C. We demonstrate the effects of CNTs/TiO2 molar ratio on the adsorption capability and photocatalytic efficiency under UV-visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO) dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO2 NPs-coated CNTs photocatalysts. The TiO2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO2.

Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes

PubMed Central

2010-01-01

A simple and straightforward approach to prepare TiO2-coated carbon nanotubes (CNTs) is presented. Anatase TiO2 nanoparticles (NPs) with the average size ~8 nm were coated on CNTs from peroxo titanic acid (PTA) precursor even at low temperature of 100 °C. We demonstrate the effects of CNTs/TiO2 molar ratio on the adsorption capability and photocatalytic efficiency under UV–visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO) dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO2 NPs-coated CNTs photocatalysts. The TiO2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO2. PMID:20671780

Scanned-probe field-emission studies of vertically aligned carbon nanofibers

NASA Astrophysics Data System (ADS)

Merkulov, Vladimir I.; Lowndes, Douglas H.; Baylor, Larry R.

2001-02-01

Field emission properties of dense and sparse "forests" of randomly placed, vertically aligned carbon nanofibers (VACNFs) were studied using a scanned probe with a small tip diameter of ˜1 μm. The probe was scanned in directions perpendicular and parallel to the sample plane, which allowed for measuring not only the emission turn-on field at fixed locations but also the emission site density over large surface areas. The results show that dense forests of VACNFs are not good field emitters as they require high extracting (turn-on) fields. This is attributed to the screening of the local electric field by the neighboring VACNFs. In contrast, sparse forests of VACNFs exhibit moderate-to-low turn-on fields as well as high emission site and current densities, and long emission lifetime, which makes them very promising for various field emission applications.

A three-dimensional interpenetrating electrode of reduced graphene oxide for selective detection of dopamine.

PubMed

Yu, Xiaowen; Sheng, Kaixuan; Shi, Gaoquan

2014-09-21

Electrochemical detection of dopamine plays an important role in medical diagnosis. In this paper, we report a three-dimensional (3D) interpenetrating graphene electrode fabricated by electrochemical reduction of graphene oxide for selective detection of dopamine. This electrochemically reduced graphene oxide (ErGO) electrode was used directly without further functionalization or blending with other functional materials. This electrode can efficiently lower the oxidation potential of ascorbic acid; thus, it is able to selectively detect dopamine in the presence of ascorbic acid and uric acid. The ErGO-based biosensor exhibited a linear response towards dopamine in the concentration range of 0.1-10 μM with a low detection limit of 0.1 μM. Furthermore, this electrode has good reproducibility and environmental stability, and can be used to analyse real samples.

Boltzmann sampling for an XY model using a non-degenerate optical parametric oscillator network

NASA Astrophysics Data System (ADS)

Takeda, Y.; Tamate, S.; Yamamoto, Y.; Takesue, H.; Inagaki, T.; Utsunomiya, S.

2018-01-01

We present an experimental scheme of implementing multiple spins in a classical XY model using a non-degenerate optical parametric oscillator (NOPO) network. We built an NOPO network to simulate a one-dimensional XY Hamiltonian with 5000 spins and externally controllable effective temperatures. The XY spin variables in our scheme are mapped onto the phases of multiple NOPO pulses in a single ring cavity and interactions between XY spins are implemented by mutual injections between NOPOs. We show the steady-state distribution of optical phases of such NOPO pulses is equivalent to the Boltzmann distribution of the corresponding XY model. Estimated effective temperatures converged to the setting values, and the estimated temperatures and the mean energy exhibited good agreement with the numerical simulations of the Langevin dynamics of NOPO phases.

The Großschwabhausen binary survey

NASA Astrophysics Data System (ADS)

Mugrauer, M.; Buder, S.; Reum, F.; Birth, A.

2017-01-01

Background: Since 2009, the Großschwabhausen binary survey is being carried out at the University Observatory Jena. This new imaging survey uses available time slots during photometric monitoring campaigns, caused by nonphotometric weather conditions, which often exhibit good atmospheric seeing. The goal of the project is to obtain current relative astrometric measurements of the binary systems that are listed in the Washington Visual Double Star Catalog. Materials and Methods: For the survey we use the Refraktor-Teleskop-Kamera at the University Observatory Jena to take imaging data of selected visual binary systems. Results: In this paper, we characterize the target sample of the survey, describe the imaging observations and the astrometric measurements including the astrometric calibration, and present the relative astrometric measures of 352 binaries that could be obtained during the course of the Großschwabhausen binary survey, so far.

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.

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.

Carbon fibers coated with graphene reinforced TiAl alloy composite with high strength and toughness.

PubMed

Cui, Sen; Cui, Chunxiang; Xie, Jiaqi; Liu, Shuangjin; Shi, Jiejie

2018-02-05

To meet the more rigorous requirement in aerospace industry, recent studies on strengthening and toughening TiAl alloys mostly focus on high Nb addition, which inevitably bring in an increasing of density. In this study, a carbon fibers coated with graphene reinforced TiAl alloy composite was fabricated by powder metallurgy, melt spun and vacuum melting. This composite got remarkable mechanical properties combined with a prominent density reduction. In contrast with pure TiAl ingots, this sample exhibits an average fracture strain from 16% up to 26.27%, and an average strength from 1801 MPa up to 2312 MPa. Thus, we can achieve a new method to fabricate this low-density, good mechanical performance TiAl composite which could bring in more opportunities for application in aerospace industry.

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.

Determination of true optical absorption and scattering coefficient of wooden cell wall substance by time-of-flight near infrared spectroscopy.

PubMed

Kitamura, Ryunosuke; Inagaki, Tetsuya; Tsuchikawa, Satoru

2016-02-22

The true absorption coefficient (μa) and reduced scattering coefficient (μ´s) of the cell wall substance in Douglas fir were determined using time-of-flight near infrared spectroscopy. Samples were saturated with hexane, toluene or quinolone to minimize the multiple reflections of light on the boundary between pore-cell wall substance in wood. μ´s exhibited its minimum value when the wood was saturated with toluene because the refractive index of toluene is close to that of the wood cell wall substance. The optical parameters of the wood cell wall substance calculated were μa = 0.030 mm(-1) and μ´s= 18.4 mm(-1). Monte Carlo simulations using these values were in good agreement with the measured time-resolved transmittance profiles.

Amperometric Immunosensors for screening of Polycyclic Aromatic Hydrocarbons in water

NASA Astrophysics Data System (ADS)

Ahmad, A.; Paschero, A.; Moore, E.

2011-08-01

An amperometric immunosensor with low limit detection was developed for the screening of polycyclic aromatic hydrocarbons (PAHs) in water. The system was based on detecting the specific substance using an immunological reaction by measuring the chemical responses to specific antibodies. An integrated biochip with a three electrode system was fabricated. Gold was used as the working electrode with platinum was used as the counter electrode. A modified Ag/AgCl reference electrode was employed to enhance the stability of the immunosensors. Indirect competition enzyme-linked immunosorbent assay (ELISA) was carried out within the electrode using alkaline phosphatase (AP) as the labelled-enzyme. The system shows acceptable reproducibility and good stability. The immunosensor exhibited a wide linear response to PAHs. A limit of detection for this sensor was in the range of 1 to 10 ng ml-1 in aqueous sample.

Electroless deposition of Au nanoparticles on reduced graphene oxide/polyimide film for electrochemical detection of hydroquinone and catechol

NASA Astrophysics Data System (ADS)

Shen, Xuan; Xia, Xiaohong; Du, Yongling; Wang, Chunming

2017-09-01

An electrochemical sensor for determination of hydroquinone (HQ) and catechol (CC) was developed using Au nanoparticles (AuNPs) fabricated on reduced graphene oxide/polyimide (PI/RGO) film by electroless deposition. The electrochemical behaviors of HQ and CC at PI/RGO-AuNPs electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimized condition, the current responses at PI/RGO-AuNPs electrode were linear over ranges from 1 to 654 mol/L for HQ and from 2 to 1289 mol/L for CC, with the detection limits of 0.09 and 0.2 mol/L, respectively. The proposed electrode exhibited good reproducibility, stability and selectivity. In addition, the proposed electrode was successfully applied in the determination of HQ and CC in tap water and the Yellow River samples.

Graphite nanocomposites sensor for multiplex detection of antioxidants in food.

PubMed

Ng, Khan Loon; Tan, Guan Huat; Khor, Sook Mei

2017-12-15

Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ) are synthetic antioxidants used in the food industry. Herein, we describe the development of a novel graphite nanocomposite-based electrochemical sensor for the multiplex detection and measurement of BHA, BHT, and TBHQ levels in complex food samples using a linear sweep voltammetry technique. Moreover, our newly established analytical method exhibited good sensitivity, limit of detection, limit of quantitation, and selectivity. The accuracy and reliability of analytical results were challenged by method validation and comparison with the results of the liquid chromatography method, where a linear correlation of more than 0.99 was achieved. The addition of sodium dodecyl sulfate as supporting additive further enhanced the LSV response (anodic peak current, I pa ) of BHA and BHT by 2- and 20-times, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination of Chromium(III), Chromium(VI), and Chromium(III) acetylacetonate in water by ion-exchange disk extraction/metal furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Kamakura, Nao; Inui, Tetsuo; Kitano, Masaru; Nakamura, Toshihiro

A new method for the separate determination of Chromium(III) (Cr(III)), Chromium(VI) (Cr(VI)), and Cr(III) acetylacetonate (Cr(acac)3) in water was developed using a cation-exchange extraction disk (CED) and an anion-exchange extraction disk (AED) combined with metal furnace atomic absorption spectrometry (MFAAS). A 100-mL water sample was adjusted to pH 5.6 and passed through the CED placed on the AED. Cr(acac)3 and Cr(III) were adsorbed on the CED, and Cr(VI) was adsorbed on the AED. The adsorbed Cr(acac)3 was eluted with 50 mL of carbon tetrachloride, followed by the elution of Cr(III) with 50 mL of 3 mol L- 1 nitric acid. Cr(VI) was eluted with 50 mL of 3 mol L- 1 nitric acid. The chemical species of Cr eluted from the CED with carbon tetrachloride was identified as Cr(acac)3 using infrared spectroscopy. The eluate of Cr(acac)3 was diluted to 100 mL with carbon tetrachloride, and those of Cr(III) and Cr(VI) were diluted to 100 mL with deionized water. All of the solutions were subsequently analyzed by MFAAS. The calibration curve for the Cr(acac)3 aqueous solutions exhibited good linearity in the range of 0.1 to 1 ng. The detection limit of Cr, which corresponded to three times the standard deviation (n = 10) of the blank values, was 20 pg. The recovery test for Cr(III), Cr(VI), and Cr(acac)3 exhibited desirable results (96.0%-107%) when 5 μg of each species (50 μg L- 1) was added to 100 mL water samples (i.e., tap water, rainwater, and bottled drinking water). In a humic acid solution, Cr(acac)3 was quantitatively recovered (103%), but Cr(III) and Cr(VI) exhibited poor recoveries (i.e., 84.8% and 78.4%, respectively).

Effects of combined plasma chromizing and shot peening on the fatigue properties of a Ti6Al4V alloy

NASA Astrophysics Data System (ADS)

Yu, Shouming; Liu, Daoxin; Zhang, Xiaohua; Du, Dongxing

2015-10-01

A plasma chromizing treatment was conducted on Ti6Al4V samples by employing the recently developed double glow plasma surface alloying technology. The Cr-alloyed layer consisted of four sub-layers, namely the Cr deposition, Cr2Ti, CrTi4, and Cr-Ti solid-solution layers. The local hardness and moduli were determined via nanoindentation. In addition, the fatigue properties of the samples were evaluated by using a rotating-bending fatigue machine under a given load. The results showed that the hardness or elastic moduli of the adjacent sub-layers differed significantly and the fatigue properties of the Ti6Al4V alloy deteriorated with the plasma chromizing treatment. This deterioration stemmed mainly from cracks initiated at the interfaces between the sub-layers and the microstructural changes of the substrate; these changes were induced by the high temperature used in the plasma chromizing process. However, the fatigue life of the plasma-chromized samples was increased by a shot peening post-treatment. The fatigue life of the samples resulting from this combination of treatments was slightly higher than that of the single-shot-peened Ti6Al4V substrate. In fact, the sample retaining only the Cr-Ti solid-solution layer (that is, the first three sub-layers were removed), when shot-peened, exhibited the highest fatigue life among all the tested samples; this was attributed to that sample having the highest residual compressive stress, the significant work hardening, and the good hardness to toughness balance.

Extemporaneously preparative biodegradable injectable polymer systems exhibiting temperature-responsive irreversible gelation.

PubMed

Yoshida, Yasuyuki; Takata, Kazuyuki; Takai, Hiroki; Kawahara, Keisuke; Kuzuya, Akinori; Ohya, Yuichi

2017-10-01

On clinical application of biodegradable injectable polymer (IP) systems, quick extemporaneous preparation of IP formulations and longer duration time gel state after injection into the body are the important targets to be developed. Previously, we had reported temperature-responsive covalent gelation systems via bio-orthogonal thiol-ene reaction by 'mixing strategy' of amphiphilic biodegradable tri-block copolymer (tri-PCG) attaching acryloyl groups on both termini (tri-PCG-Acryl) with reactive polythiol. In other previous works, we found 'freeze-dry with PEG/dispersion' method as quick extemporaneous preparation method of biodegradable IP formulations. In this study, we applied this quick preparative method to the temperature-triggered covalent gelation system. The instant formulation (D-sample) could be prepared by 'freeze-dry with PEG/dispersion' just mixing of tri-PCG-Acryl micelle dispersion and tri-PCG/DPMP micelle dispersion with PEG, that can be prepared in 30 s from the dried samples. The obtained D-sample showed irreversible gelation and long duration time of gel state, which was basically the same as the formulations prepared by the usual heating dissolution method (S-sample). Interestingly, the D-sample could maintain its sol state for a longer time (24 h) after preparing the formulation at r.t. compared with the S-sample, which became a gel in 3 h after preparing. The IP system showed good biocompatibility and long duration time of the gel state after subcutaneous implantation. These characteristics of D-samples, quick extemporaneous preparation and high stability in the sol state before injection, would be very convenient in a clinical setting.

Method of improving system performance and survivability through changing function

NASA Technical Reports Server (NTRS)

Hinchey, Michael G. (Inventor); Vassev, Emil I. (Inventor)

2012-01-01

A biologically-inspired system and method is provided for self-adapting behavior of swarm-based exploration missions, whereby individual components, for example, spacecraft, in the system can sacrifice themselves for the greater good of the entire system. The swarm-based system can exhibit emergent self-adapting behavior. Each component can be configured to exhibit self-sacrifice behavior based on Autonomic System Specification Language (ASSL).

A novel, two-step top seeded infiltration and growth process for the fabrication of single grain, bulk (RE)BCO superconductors

NASA Astrophysics Data System (ADS)

Namburi, Devendra K.; Shi, Yunhua; Palmer, Kysen G.; Dennis, Anthony R.; Durrell, John H.; Cardwell, David A.

2016-09-01

A fundamental requirement of the fabrication of high performing, (RE)-Ba-Cu-O bulk superconductors is achieving a single grain microstructure that exhibits good flux pinning properties. The top seeded melt growth (TSMG) process is a well-established technique for the fabrication of single grain (RE)BCO bulk samples and is now applied routinely by a number of research groups around the world. The introduction of a buffer layer to the TSMG process has been demonstrated recently to improve significantly the general reliability of the process. However, a number of growth-related defects, such as porosity and the formation of micro-cracks, remain inherent to the TSMG process, and are proving difficult to eliminate by varying the melt process parameters. The seeded infiltration and growth (SIG) process has been shown to yield single grain samples that exhibit significantly improved microstructures compared to the TSMG technique. Unfortunately, however, SIG leads to other processing challenges, such as the reliability of fabrication, optimisation of RE2BaCuO5 (RE-211) inclusions (size and content) in the sample microstructure, practical oxygenation of as processed samples and, hence, optimisation of the superconducting properties of the bulk single grain. In the present paper, we report the development of a near-net shaping technique based on a novel two-step, buffer-aided top seeded infiltration and growth (BA-TSIG) process, which has been demonstrated to improve greatly the reliability of the single grain growth process and has been used to fabricate successfully bulk, single grain (RE)BCO superconductors with improved microstructures and superconducting properties. A trapped field of ˜0.84 T and a zero field current density of 60 kA cm-2 have been measured at 77 K in a bulk, YBCO single grain sample of diameter 25 mm processed by this two-step BA-TSIG technique. To the best of our knowledge, this value of trapped field is the highest value ever reported for a sample fabricated by an infiltration and growth process. In this study we report the successful fabrication of 14 YBCO samples, with diameters of up to 32 mm, by this novel technique with a success rate of greater than 92%.

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.

A Comparative Assessment of the Influences of Human Impacts on Soil Cd Concentrations Based on Stepwise Linear Regression, Classification and Regression Tree, and Random Forest Models

PubMed Central

Qiu, Lefeng; Wang, Kai; Long, Wenli; Wang, Ke; Hu, Wei; Amable, Gabriel S.

2016-01-01

Soil cadmium (Cd) contamination has attracted a great deal of attention because of its detrimental effects on animals and humans. This study aimed to develop and compare the performances of stepwise linear regression (SLR), classification and regression tree (CART) and random forest (RF) models in the prediction and mapping of the spatial distribution of soil Cd and to identify likely sources of Cd accumulation in Fuyang County, eastern China. Soil Cd data from 276 topsoil (0–20 cm) samples were collected and randomly divided into calibration (222 samples) and validation datasets (54 samples). Auxiliary data, including detailed land use information, soil organic matter, soil pH, and topographic data, were incorporated into the models to simulate the soil Cd concentrations and further identify the main factors influencing soil Cd variation. The predictive models for soil Cd concentration exhibited acceptable overall accuracies (72.22% for SLR, 70.37% for CART, and 75.93% for RF). The SLR model exhibited the largest predicted deviation, with a mean error (ME) of 0.074 mg/kg, a mean absolute error (MAE) of 0.160 mg/kg, and a root mean squared error (RMSE) of 0.274 mg/kg, and the RF model produced the results closest to the observed values, with an ME of 0.002 mg/kg, an MAE of 0.132 mg/kg, and an RMSE of 0.198 mg/kg. The RF model also exhibited the greatest R2 value (0.772). The CART model predictions closely followed, with ME, MAE, RMSE, and R2 values of 0.013 mg/kg, 0.154 mg/kg, 0.230 mg/kg and 0.644, respectively. The three prediction maps generally exhibited similar and realistic spatial patterns of soil Cd contamination. The heavily Cd-affected areas were primarily located in the alluvial valley plain of the Fuchun River and its tributaries because of the dramatic industrialization and urbanization processes that have occurred there. The most important variable for explaining high levels of soil Cd accumulation was the presence of metal smelting industries. The good performance of the RF model was attributable to its ability to handle the non-linear and hierarchical relationships between soil Cd and environmental variables. These results confirm that the RF approach is promising for the prediction and spatial distribution mapping of soil Cd at the regional scale. PMID:26964095

A Comparative Assessment of the Influences of Human Impacts on Soil Cd Concentrations Based on Stepwise Linear Regression, Classification and Regression Tree, and Random Forest Models.

PubMed

Qiu, Lefeng; Wang, Kai; Long, Wenli; Wang, Ke; Hu, Wei; Amable, Gabriel S

2016-01-01

Soil cadmium (Cd) contamination has attracted a great deal of attention because of its detrimental effects on animals and humans. This study aimed to develop and compare the performances of stepwise linear regression (SLR), classification and regression tree (CART) and random forest (RF) models in the prediction and mapping of the spatial distribution of soil Cd and to identify likely sources of Cd accumulation in Fuyang County, eastern China. Soil Cd data from 276 topsoil (0-20 cm) samples were collected and randomly divided into calibration (222 samples) and validation datasets (54 samples). Auxiliary data, including detailed land use information, soil organic matter, soil pH, and topographic data, were incorporated into the models to simulate the soil Cd concentrations and further identify the main factors influencing soil Cd variation. The predictive models for soil Cd concentration exhibited acceptable overall accuracies (72.22% for SLR, 70.37% for CART, and 75.93% for RF). The SLR model exhibited the largest predicted deviation, with a mean error (ME) of 0.074 mg/kg, a mean absolute error (MAE) of 0.160 mg/kg, and a root mean squared error (RMSE) of 0.274 mg/kg, and the RF model produced the results closest to the observed values, with an ME of 0.002 mg/kg, an MAE of 0.132 mg/kg, and an RMSE of 0.198 mg/kg. The RF model also exhibited the greatest R2 value (0.772). The CART model predictions closely followed, with ME, MAE, RMSE, and R2 values of 0.013 mg/kg, 0.154 mg/kg, 0.230 mg/kg and 0.644, respectively. The three prediction maps generally exhibited similar and realistic spatial patterns of soil Cd contamination. The heavily Cd-affected areas were primarily located in the alluvial valley plain of the Fuchun River and its tributaries because of the dramatic industrialization and urbanization processes that have occurred there. The most important variable for explaining high levels of soil Cd accumulation was the presence of metal smelting industries. The good performance of the RF model was attributable to its ability to handle the non-linear and hierarchical relationships between soil Cd and environmental variables. These results confirm that the RF approach is promising for the prediction and spatial distribution mapping of soil Cd at the regional scale.

Copper-Catalyzed Electrophilic Amination of Organoaluminum Nucleophiles with O-Benzoyl Hydroxylamines.

PubMed

Zhou, Shuangliu; Yang, Zhiyong; Chen, Xu; Li, Yimei; Zhang, Lijun; Fang, Hong; Wang, Wei; Zhu, Xiancui; Wang, Shaowu

2015-06-19

A copper-catalyzed electrophilic amination of aryl and heteroaryl aluminums with N,N-dialkyl-O-benzoyl hydroxylamines that affords the corresponding anilines in good yields has been developed. The catalytic reaction proceeds very smoothly under mild conditions and exhibits good substrate scope. Moreover, the developed catalytic system is also well suited for heteroaryl aluminum nucleophiles, providing facile access to heteroaryl amines.

Quality of life amongst older Brazilians: a cross-cultural validation of the CASP-19 into Brazilian-Portuguese.

PubMed

Lima, Fábia M; Hyde, Martin; Chungkham, Holendro Singh; Correia, Clarice; Siqueira Campos, Alexsandra; Campos, Marília; Novaes, Moacir; Laks, Jerson; Petribu, Kátia

2014-01-01

As population ageing becomes a global phenomenon the need to understand the quality of life of older people around the world has become increasingly salient. The CASP-19 is a well established measure of quality of later life. The scale is composed of 19 items which map onto the four domains of control (C), Autonomy (A), Self-Realisation (S) and Pleasure (P). It has already been translated to 12 languages and has been used in a number of national and international studies. However use of the scale outside of Europe has been very limited. The objective of this study was to translate and evaluate the use of the CASP-19 amongst older Brazilians. The CASP-19 was translated from English to Portuguese, back-translated and submitted to an analysis of equivalence by a committee of judges. The scale was then administered to a sample of community dwelling older people in Recife, Brazil (n = 87), and tested for psychometric properties. The Control and Pleasure domains exhibited good internal consistency. By removing one item from each of the Autonomy and Self Realisation domains their internal consistency was improved. The mean age of the sample was 75.6±0.7 years, subjects were mainly female (52.9%), white (52.9%), who lived without a partner (54%), and had a monthly income varying from USD 340.00 to USD 850.00. Translation and cross-cultural adaptation permitted good understanding and applicability of final version. Psychometric analyses revealed that the removal of two items improved the internal consistency of the Autonomy and Pleasure domains. Confirmatory factor analyses suggest that a 16 item, four factor, model best fits the data. In this small exploratory study the CASP-19 Brazil demonstrated good psychometric properties. It was easy to use for both participants and researchers. Hopefully future studies in Brazil will employ the scale so that more direct cross national comparisons can be made with older people in Europe and the US.

Fast and high-efficiency magnetic surface imprinting based on microwave-accelerated reversible addition fragmentation chain transfer polymerization for the selective extraction of estrogen residues in milk.

PubMed

Chen, Fangfang; Wang, Jiayu; Lu, Ruicong; Chen, Huiru; Xie, Xiaoyu

2018-08-10

A novel microwave-accelerated reversible addition fragmentation chain transfer (RAFT) polymerization strategy has been introduced to shorten reaction time and improved polymerization efficiency of the conventional molecularly imprinting technology based on RAFT. Magnetic molecular imprinted polymers (MMIPs) were successfully synthesized much more efficiently using 17β-estradiol (E2) as a template for the determination of estrogen residues. The resultant MMIPs had well-defined thin imprinted film, favoring the fast mass transfer. Moreover, the reaction time, which was just 1/24 of the time taken by conventional heating, was significantly decreased, improving the reaction efficiency and reducing the probability of side reactions. Meanwhile, the obtained polymers have good capacity of 6.67 mg g -1 and satisfactory selectivity to template molecule with the imprinting factor of 5.11. As a result, a method combination of the resultant MMIPs as solid phase extraction sorbents and high-performance liquid chromatography was successfully set up to determinate three estrogen residues in milk samples. For E2, estrone, and estriol, the limit of detections were calculated to be 0.03, 0.08, and 0.06 ng mL -1 , respectively, and the limit of quantifications were 0.11, 0.27, and 0.21 ng mL -1 , respectively. At the spiked level of 1, 5, and 10 ng mL -1 , the recoveries of the three estrogens were ranged from 69.1% to 91.9% and the intra-day relative standard deviation (RSD) was less than 5.7%. In addition, the resultant MMIPs exhibited good reproducibility and reusability with the inter-batch RSD of 5.3% and the intra-batch RSD of 6.2%, respectively. Overall, the realization of this strategy facilitates the preparation of MMIPs with good architecture and high reaction efficiencies for the analysis of complicated real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

High-energy coordination polymers (CPs) exhibiting good catalytic effect on the thermal decomposition of ammonium dinitramide

NASA Astrophysics Data System (ADS)

Li, Xin; Han, Jing; Zhang, Sheng; Zhai, Lianjie; Wang, Bozhou; Yang, Qi; Wei, Qing; Xie, Gang; Chen, Sanping; Gao, Shengli

2017-09-01

High-energy coordination polymers (CPs) not only exhibit good energetic performances but also have a good catalytic effect on the thermal decomposition of energetic materials. In this contribution, two high-energy CPs Cu2(DNBT)2(CH3OH)(H2O)3·3H2O (1) and [Cu3(DDT)2(H2O)2]n (2) (H2DNBT = 3,3‧-dinitro-5,5‧-bis(1H-1,2,4-triazole and H3DDT = 4,5-bis(1H-tetrazol-5-yl)-2H-1,2,3-triazole) were synthesized and structurally characterized. Furthermore, 1 was thermos-dehydrated to produce Cu2(DNBT)2(CH3OH)(H2O)3 (1a). The thermal decomposition kinetics of 1, 1a and 2 were studied by Kissinger's method and Ozawa's method. Thermal analyses and sensitivity tests show that all compounds exhibit high thermal stability and low sensitivity for external stimuli. Meanwhile, all compounds have large positive enthalpy of formation, which are calculated as being (1067.67 ± 2.62) kJ mol-1 (1), (1464.12 ± 3.12) kJ mol-1 (1a) and (3877.82 ± 2.75) kJ mol-1 (2), respectively. The catalytic effects of 1a and 2 on the thermal decomposition of ammonium dinitramide (ADN) were also investigated.

The Swedish translation and cross-cultural adaptation of the Functional Assessment of Chronic Illness Therapy - Cervical Dysplasia (FACIT-CD): linguistic validity and reliability of the Swedish version.

PubMed

Rask, Marie; Oscarsson, Marie; Ludwig, Neil; Swahnberg, Katarina

2017-04-04

Cervical dysplasia is a precancerous condition, which has been shown to create anxiety in women. To be able to investigate these women's health-related quality of life, a disease-specific instrument is required. There does not seem to be a Swedish version of an instrument to screen for this specific disease. Therefore, this study aims to translate and cross-culturally adapt the Functional Assessment of Chronic Illness Therapy - Cervical Dysplasia (FACIT-CD) into a Swedish context and evaluate its linguistic validity and reliability. The Functional Assessment of Chronic Illness Therapy (FACIT) translation methodology was used, which consists of several steps including pilot testing of the FACIT-CD instrument through cognitive debriefing interviews. Ten women diagnosed with cervical dysplasia participated in the cognitive debriefing interviews. The internal consistency reliability of the Swedish FACIT-CD was estimated by Cronbach's alpha coefficient. Homogeneity of the items was evaluated by corrected item-total correlations. The sample consists of 34 women who were diagnosed with cervical dysplasia. The translation and cross-cultural adaptation went smoothly without any problems for the majority of the items. The cognitive debriefing interviews indicated that the Swedish FACIT-CD consists of relevant items, is easy to understand and complete, and has unambiguous and comprehensive response categories. The translation and cross-cultural adaptation resulted in a Swedish FACIT-CD, which is conceptually and semantically equivalent to the English version and linguistically valid. The total scale of the Swedish FACIT-CD exhibited good internal consistency reliability with a Cronbach's alpha coefficient of 0.84, and all of the subscales exhibited acceptable value between 0.71 and 0.81 except the Relationships subscale, which had a value of 0.67. Finally, all but four items exceeded the acceptable level for the corrected item-total correlations of ≥ 0.20. The Swedish FACIT-CD is conceptually and semantically equivalent to the English version and linguistically valid; further, it exhibits good internal consistency reliability.

Development of sensitive determination method for fungicides from environmental water samples with Titanate nanotube array micro-solid phase extraction prior to high performance liquid chromatography.

PubMed

Huang, Yunrui; Zhou, Qingxiang; Xie, Guohong

2013-01-01

Fungicides have been widely used throughout the world, and the resulted pollution has absorbed great attention in recent years. Present study described an effective measurement technique for fungicides including thiram, metalaxyl, diethofencarb, myclobutanil and tebuconazole in environmental water samples. A micro-solid phase extraction (μSPE) was developed utilizing ordered TiO(2) nanotube array for determination of target fungicides prior to a high performance liquid chromatography (HPLC). The experimental results indicated that TiO(2) nanotube arrays demonstrated excellent merits on the preconcentration of fungicides, and excellent linear relationship between peak area and the concentration of fungicides was obtained in the range of 0.1-50 μg L(-1). The detection limits for the targeted fungicides were in the range of 0.016-0.086 μg L(-1) (S/N=3). Four real environmental water samples were used to validate the applicability of the proposed method, and good spiked recoveries in the range of 73.9-114% were achieved. A comparison of present method with conventional solid phase extraction was made and the results exhibited that proposed method resulted in better recoveries. The results demonstrated that this μ-SPE technique was a viable alternative for the analysis of fungicides in complex samples. Copyright © 2012 Elsevier Ltd. All rights reserved.

Production and mechanical properties of Ti-5Al-2.5Fe-xCu alloys for biomedical applications.

PubMed

Yamanoglu, Ridvan; Efendi, Erdinc; Kolayli, Fetiye; Uzuner, Huseyin; Daoud, Ismail

2018-01-30

In this study, the mechanical, antibacterial properties and cell toxicity response of Ti-5Al2.5Fe alloy with different copper contents were investigated. The alloys were prepared by high-energy ball milling using elemental Ti, Al, Fe, and Cu powders and consolidated by a uniaxial vacuum hot press. Staphylococcus aureus strain ATCC 29213 and Escherichia coli strain ATCC 25922 were used to determine the antibacterial properties of the sintered alloys. The in vitro cytotoxicity of the samples was evaluated with HeLa (ATTC, CCL-2) cells using thiazolyl blue tetrazolium bromide. The mechanical behavior of the samples was determined as a function of hardness and bending tests and analyzed by scanning electron microscopy, energy dispersive x-ray spectroscopy, optical microscopy and x-ray diffraction (XRD). The results showed that the Cu content significantly improved the antibacterial properties. Cu addition prevented the formation of E. coli and S. aureus colonies on the surface of the samples. All samples exhibited very good cell biocompatibility. The alloys with different copper contents showed different mechanical properties, and the results were correlated by microstructural and XRD analyses in detail. Our results showed that Cu has a great effect on the Ti5Al2.5Fe alloy and the alloy is suitable for biomedical applications with enhanced antibacterial activity.

Band structure and visible light photocatalytic activity of multi-type nitrogen doped TiO(2) nanoparticles prepared by thermal decomposition.

PubMed

Dong, Fan; Zhao, Weirong; Wu, Zhongbiao; Guo, Sen

2009-03-15

Multi-type nitrogen doped TiO(2) nanoparticles were prepared by thermal decomposition of the mixture of titanium hydroxide and urea at 400 degrees C for 2h. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (UV-vis DRS), and photoluminescence (PL). The results showed that the as-prepared samples exhibited strong visible light absorption due to multi-type nitrogen doped in the form of substitutional (N-Ti-O and Ti-O-N) and interstitial (pi* character NO) states, which were 0.14 and 0.73 eV above the top of the valence band, respectively. A physical model of band structure was established to clarify the visible light photocatalytic process over the as-prepared samples. The photocatalytic activity was evaluated for the photodegradation of gaseous toluene under visible light irradiation. The activity of the sample prepared from wet titanium hydroxide and urea (TiO(2)-Nw, apparent reaction rate constant k = 0.045 min(-1)) was much higher than other samples including P25 (k = 0.0013 min(-1)). The high activity can be attributed to the results of the synergetic effects of strong visible light absorption, good crystallization, large surface hydroxyl groups, and enhanced separation of photoinduced carriers.

Local sample thickness determination via scanning transmission electron microscopy defocus series.

PubMed

Beyer, A; Straubinger, R; Belz, J; Volz, K

2016-05-01

The usable aperture sizes in (scanning) transmission electron microscopy ((S)TEM) have significantly increased in the past decade due to the introduction of aberration correction. In parallel with the consequent increase of convergence angle the depth of focus has decreased severely and optical sectioning in the STEM became feasible. Here we apply STEM defocus series to derive the local sample thickness of a TEM sample. To this end experimental as well as simulated defocus series of thin Si foils were acquired. The systematic blurring of high resolution high angle annular dark field images is quantified by evaluating the standard deviation of the image intensity for each image of a defocus series. The derived dependencies exhibit a pronounced maximum at the optimum defocus and drop to a background value for higher or lower values. The full width half maximum (FWHM) of the curve is equal to the sample thickness above a minimum thickness given by the size of the used aperture and the chromatic aberration of the microscope. The thicknesses obtained from experimental defocus series applying the proposed method are in good agreement with the values derived from other established methods. The key advantages of this method compared to others are its high spatial resolution and that it does not involve any time consuming simulations. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Monitoring dissolved orthophosphate in a struvite precipitation reactor with a voltammetric electronic tongue.

PubMed

Aguado, Daniel; Barat, Ramón; Soto, Juan; Martínez-Mañez, Ramón

2016-10-01

This study demonstrates the feasibility of using a voltammetric electronic tongue to monitor effluent dissolved orthophosphate concentration in a struvite precipitation reactor. The electrochemical response of the electronic tongue to the presence of orthophosphate in samples collected from the effluent of the precipitation reactor is used to predict orthophosphate concentration via a statistical model based on Partial Least Squares (PLS) Regression. PLS predictions were suitable for this monitoring application in which precipitation efficiencies higher than 80% (i.e., effluent dissolved orthophosphate concentrations lower than 40mg P-PO4(3-) L(-1)) could be considered as indicator of good process performance. The electronic tongue consisted of a set of metallic (noble and non-noble) electrodes housed inside a stainless steel cylinder which was used as the body of the electronic tongue system. Fouling problems were prevented via a simple mechanical polishing of the electrodes. The measurement of each sample with the electronic tongue was done in less than 3s. Conductivity of the samples only affected the electronic tongue marginally, being the main electrochemical response due to the orthophosphate concentration in the samples. Copper, silver, iridium and rhodium were the electrodes that exhibited noticeable response correlated with the dissolved orthophosphate concentration variations, while gold, platinum and especially cobalt and nickel were the less useful electrodes for this application. Copyright © 2016 Elsevier B.V. All rights reserved.

Looking Good or Being Good? The Role of Social Desirability Tendencies in Student Perceptions of Institutional Mission and Values

ERIC Educational Resources Information Center

Ferrari, Joseph R.; Bristow, Maya; Cowman, Shaun E.

2005-01-01

Two samples of college students (Sample 1, n = 106 Sample 2, n = 107) completed self-report measures that assessed their perceptions of their university's mission and values along with their tendency to seek social approval. With Sample 1, global social desirability was not predictive of any student perceptions related to institutional mission and…

Inactivated human platelet lysate with psoralen: a new perspective for mesenchymal stromal cell production in Good Manufacturing Practice conditions.

PubMed

Castiglia, Sara; Mareschi, Katia; Labanca, Luciana; Lucania, Graziella; Leone, Marco; Sanavio, Fiorella; Castello, Laura; Rustichelli, Deborah; Signorino, Elena; Gunetti, Monica; Bergallo, Massimiliano; Bordiga, Anna Maria; Ferrero, Ivana; Fagioli, Franca

2014-06-01

Mesenchymal stromal cells (MSC) are ideal candidates for regenerative and immunomodulatory therapies. The use of xenogeneic protein-free Good Manufacturing Practice-compliant growth media is a prerequisite for clinical MSC isolation and expansion. Human platelet lysate (HPL) has been efficiently implemented into MSC clinical manufacturing as a substitute for fetal bovine serum (FBS). Because the use of human-derived blood materials alleviates immunologic risks but not the transmission of blood-borne viruses, the aim of our study was to test an even safer alternative than HPL to FBS: HPL subjected to pathogen inactivation by psoralen (iHPL). Bone marrow samples were plated and expanded in α-minimum essential medium with 10% of three culture supplements: HPL, iHPL and FBS, at the same time. MSC morphology, growth and immunophenotype were analyzed at each passage. Karyotype, tumorigenicity and sterility were analyzed at the third passage. Statistical analyses were performed. The MSCs cultivated in the three different culture conditions showed no significant differences in terms of fibroblast colony-forming unit number, immunophenotype or in their multipotent capacity. Conversely, the HPL/iHPL-MSCs were smaller, more numerous, had a higher proliferative potential and showed a higher Oct-3/4 and NANOG protein expression than did FBS-MSCs. Although HPL/iHPL-MSCs exhibit characteristics that may be attributable to a higher primitive stemness than FBS-MSCs, no tumorigenic mutations or karyotype modifications were observed. We demonstrated that iHPL is safer than HPL and represents a good, Good Manufacturing Practice-compliant alternative to FBS for MSC clinical production that is even more advantageous in terms of cellular growth and stemness. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Expression and Functional Properties of an Anti-Triazophos High-Affinity Single-Chain Variable Fragment Antibody with Specific Lambda Light Chain

PubMed Central

Liu, Rui; Liang, Xiao; Xiang, Dandan; Guo, Yirong; Liu, Yihua; Zhu, Guonian

2016-01-01

Triazophos is a widely used organophosphorous insecticide that has potentially adverse effects to organisms. In the present study, a high-affinity single-chain variable fragment (scFv) antibody with specific lambda light chain was developed for residue monitoring. First, the specific variable regions were correctly amplified from a hybridoma cell line 8C10 that secreted monoclonal antibody (mAb) against triazophos. The regions were then assembled as scFv via splicing by overlap extension polymerase chain reaction. Subsequently, the recombinant anti-triazophos scFv-8C10 was successfully expressed in Escherichia coli strain HB2151 in soluble form, purified through immobilized metal ion affinity chromatography, and verified via Western blot and peptide mass fingerprinting analyses. Afterward, an indirect competitive enzyme-linked immunosorbent assay was established based on the purified anti-triazophos scFv-8C10 antibody. The assay exhibited properties similar to those based on the parent mAb, with a high sensitivity (IC50 of 1.73 ng/mL) to triazophos and no cross reaction for other organophosphorus pesticides; it was reliable in detecting triazophos residues in spiked water samples. Moreover, kinetic measurement using a surface plasmon resonance biosensor indicated that the purified scFv-8C10 antibody had a high affinity of 1.8 × 10−10 M and exhibited good binding stability. Results indicated that the recombinant high-affinity scFv-8C10 antibody was an effective detection material that would be promising for monitoring triazophos residues in environment samples. PMID:27338340

Wetting Behavior of Calcium Ferrite Slags on Cristobalite Substrates

NASA Astrophysics Data System (ADS)

Yang, Mingrui; Lv, Xuewei; Wei, Ruirui; Xu, Jian; Bai, Chenguang

2018-03-01

Calcium ferrite (CF) is a significant intermediate adhesive phase in high-basicity sinters. The wettability between calcium ferrite (CF) and gangue plays an important role in the assimilation process. The wettability of CF-based slags, in which a constant amount (2 mass pct.) of Al2O3, MgO, SiO2, and TiO2 was added, on solid SiO2 (cristobalite) substrates at 1523 K (1250 °C) was investigated. The interfacial microstructure and spreading mechanisms were discussed for each sample. All the tested slag samples exhibited good wettability on the SiO2 substrate. The initial apparent contact angles were in the range of 20 to 50 deg, while the final apparent contact angles were 5 deg. The wetting process could be divided into three stages on the basis of the change in diameter, namely the "linear spreading" stage, "spreading rate reduction" stage, and "wetting equilibrium" stage. It was found that the CF-SiO2 wetting system exhibits dissolutive wetting and the dissolution of SiO2 into slag influences its spreading process. The spreading rate increases with a decrease in the ratio of viscosity to interfacial tension, which is a result of the addition of Al2O3, MgO, SiO2, and TiO2. After cooling, a deep corrosion pit was formed in the substrate and a diffusion layer was generated in front of the residual slag zone; further, some SiO2 and Fe2O3 solid solutions precipitated in the slag.

Seismic properties of the upper mantle beneath Lanzarote (Canary Islands): Model predictions based on texture measurements by EBSD

NASA Astrophysics Data System (ADS)

Vonlanthen, Pierre; Kunze, Karsten; Burlini, Luigi; Grobety, Bernard

2006-12-01

We present a petrophysical analysis of upper mantle xenoliths, collected in the Quaternary alkali basalt fields (Series III and IV) from the island of Lanzarote. The samples consist of eight harzburgite and four dunite nodules, 5 to 15 cm in size, and exhibit a typical protogranular to porphyroclastic texture. An anomalous foliation resulting from strong recovery processes is observed in half of the specimens. The lattice preferred orientations (LPO) of olivine, orthopyroxene and clinopyroxene were measured using electron backscatter diffraction (EBSD). In most samples, olivine exhibits LPOs intermediate between the typical single crystal texture and the [100] fiber texture. Occasionally, the [010] fiber texture was also observed. Simultaneous occurrence of both types of fiber textures suggests the existence of more than one deformation regime, probably dominated by a simple shear component under low strain rate and moderate to high temperature. Orthopyroxene and clinopyroxene display a weaker but significant texture. The LPO data were used to calculate the seismic properties of the xenoliths at PT conditions obtained from geothermobarometry, and were compared to field geophysical data reported from the literature. The velocity of P-waves (7.9 km/s) obtained for a direction corresponding to the existing seismic transect is in good agreement with the most recent geophysical interpretation. Our results are consistent with a roughly W-E oriented fastest P-wave propagation direction in the uppermost mantle beneath the Canary Islands, and with the lithosphere structure proposed by previous authors involving a crust-mantle boundary at around 18 km in depth, overlaid by intermediate material between 11 and 18 km.

Comparative study of qualitative and quantitative methods to determine toxicity level of Aspergillus flavus isolates in maize.

PubMed

Shekhar, Meena; Singh, Nirupma; Dutta, Ram; Kumar, Shrvan; Mahajan, Vinay

2017-01-01

An attempt was made to compare between easy and inexpensive qualitative method (ammonia vapour test) and analytical methods (thin layer chromatography and enzyme-linked immunosorbent assay) for identification of aflatoxigenic isolates of Aspergillus flavus in maize. In this comparative study the toxicity level of A. flavus isolates exhibited 100% agreement among ammonia vapour test, ELISA and TLC for highly toxigenic (>2000 ppb) and toxigenic (501-2000 ppb) isolates while 88.5% agreement observed for least toxic (<20 ppb) isolates. In ammonia vapour test 51% of A. flavus isolates showed creamish or no colour change corresponding to least toxic/atoxic (<20ppb) category estimated by ELISA. Similarly 22% highly toxic isolates exhibited plum red colour, 12% moderately toxic indicated pink colour and 10% toxic isolates showed red colour. However, 11.5% isolates were found to be false positive in cream colour category (least toxic) and 28.5% false negatives in pink colour (moderately toxic) category. The isolates from different agroclimatic zones of maize in India showed high variability for aflatoxin B1 (AFB1) production potential ranging from 0.214-8116.61 ppb. Toxigenic potential of Aspergillus flavus isolates in culture was further validated by inoculating maize grain sample with four different isolates with varied toxin producing ability. With good agreement percentage between cultural and analytical methods the study concludes the ammonia vapour test to be easy, inexpensive, reliable and time saving method that can be used for segregating or pre-screening of contaminated samples from bulk food/feed stock.

Wetting Behavior of Calcium Ferrite Slags on Cristobalite Substrates

NASA Astrophysics Data System (ADS)

Yang, Mingrui; Lv, Xuewei; Wei, Ruirui; Xu, Jian; Bai, Chenguang

2018-06-01

Calcium ferrite (CF) is a significant intermediate adhesive phase in high-basicity sinters. The wettability between calcium ferrite (CF) and gangue plays an important role in the assimilation process. The wettability of CF-based slags, in which a constant amount (2 mass pct.) of Al2O3, MgO, SiO2, and TiO2 was added, on solid SiO2 (cristobalite) substrates at 1523 K (1250 °C) was investigated. The interfacial microstructure and spreading mechanisms were discussed for each sample. All the tested slag samples exhibited good wettability on the SiO2 substrate. The initial apparent contact angles were in the range of 20 to 50 deg, while the final apparent contact angles were 5 deg. The wetting process could be divided into three stages on the basis of the change in diameter, namely the "linear spreading" stage, "spreading rate reduction" stage, and "wetting equilibrium" stage. It was found that the CF-SiO2 wetting system exhibits dissolutive wetting and the dissolution of SiO2 into slag influences its spreading process. The spreading rate increases with a decrease in the ratio of viscosity to interfacial tension, which is a result of the addition of Al2O3, MgO, SiO2, and TiO2. After cooling, a deep corrosion pit was formed in the substrate and a diffusion layer was generated in front of the residual slag zone; further, some SiO2 and Fe2O3 solid solutions precipitated in the slag.

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

Tsai, Ming-Hung; School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan; Haung, Chiung-Fang

In this study, neodymium-doped yttrium orthovanadate (Nd:YVO{sub 4}) as a laser source with different scanning speeds was used on biomedical Ti surface. The microstructural and biological properties of laser-modified samples were investigated by means of optical microscope, electron microscope, X-ray diffraction, surface roughness instrument, contact angle and cell cytotoxicity assay. After laser modification, the rough volcano-like recast layer with micro-/nanoporous structure and wave-like recast layer with nanoporous structure were generated on the surfaces of laser-modified samples, respectively. It was also found out that, an α → (α + rutile-TiO{sub 2}) phase transition occurred on the recast layers of laser-modified samples.more » The Ti surface becomes hydrophilic at a high speed laser scanning. Moreover, the cell cytotoxicity assay demonstrated that laser-modified samples did not influence the cell adhesion and proliferation behaviors of osteoblast (MG-63) cell. The laser with 50 mm/s scanning speed induced formation of rough volcano-like recast layer accompanied with micro-/nanoporous structure, which can promote cell adhesion and proliferation of MG-63 cell on Ti surface. The results indicated that the laser treatment was a potential technology to enhance the biocompatibility for titanium. - Highlights: • Laser induced the formation of recast layer with micro-/nanoporous structure on Ti. • An α → (α + rutile-TiO{sub 2}) phase transition was observed within the recast layer. • The Ti surface becomes hydrophilic at a high speed laser scanning. • Laser-modified samples exhibit good biocompatibility to osteoblast (MG-63) cell.« less

Detection of trace fluoride in serum and urine by online membrane-based distillation coupled with ion chromatography.

PubMed

Lou, Chaoyan; Guo, Dandan; Wang, Nani; Wu, Shuchao; Zhang, Peimin; Zhu, Yan

2017-06-02

An online membrane-based distillation (MBD) coupled with ion chromatography (IC) method was proposed for automatic detection of trace fluoride (F - ) in serum and urine samples. The system consisted of a sample vessel, a lab-made membrane module and an ion chromatograph. Hydrophobic polytetrafluoroethylene (PTFE) hollow fiber membrane was used in MBD which was directly performed in serum and urine samples to eliminate the matrix interferences and enrich fluoride, while enabling automation. The determination of fluoride in biological samples was carried out by IC with suppressed conductometric detection. The proposed method feasibly determined trace fluoride in serum and urine matrices with the optimized parameters, such as acid concentration, distillation temperature, and distillation time, etc. Fluoride exhibited satisfactory linearity in the range of 0.01-5.0mg/L with a correlation coefficient of 0.9992. The limit of detection (LOD, S/N=3) and limit of quantification (LOQ, S/N=10) were 0.78μg/L and 2.61μg/L, respectively. The relative standard deviations of peak area and peak height were all less than 5.15%. The developed method was validated for the determination of fluoride in serum and urine with good spiked recoveries ranging between 97.1-101.9%. This method also can be proposed as a suitable alternative for the analysis of fluoride in other complex biological samples. Copyright © 2017. Published by Elsevier B.V.

Synthesis and Characterization of High-Dielectric-Constant Nanographite-Polyurethane Composite

NASA Astrophysics Data System (ADS)

Mishra, Praveen; Bhat, Badekai Ramachandra; Bhattacharya, B.; Mehra, R. M.

2018-05-01

In the face of ever-growing demand for capacitors and energy storage devices, development of high-dielectric-constant materials is of paramount importance. Among various dielectric materials available, polymer dielectrics are preferred for their good processability. We report herein synthesis and characterization of nanographite-polyurethane composite with high dielectric constant. Nanographite showed good dispersibility in the polyurethane matrix. The thermosetting nature of polyurethane gives the composite the ability to withstand higher temperature without melting. The resultant composite was studied for its dielectric constant (ɛ) as a function of frequency. The composite exhibited logarithmic variation of ɛ from 3000 at 100 Hz to 225 at 60 kHz. The material also exhibited stable dissipation factor (tan δ) across the applied frequencies, suggesting its ability to resist current leakage.

Reviews Exhibitions: Collider: Step inside the World's Greatest Experiment Equipment: Hero Steam Turbine Classroom Video: Most of Our Universe is Missing Book: Serving the Reich Book: Breakthrough to CLIL for Physics Book: The Good Research Guide Apps: Popplet Web Watch Apps

NASA Astrophysics Data System (ADS)

2014-03-01

WE RECOMMEND Collider: step inside the world's greatest experiment A great exhibition at the Science Museum in London Hero Steam Turbine Superb engine model gets up to 2500 rpm Most of Our Universe is Missing BBC video explores the dark truth Serving the Reich Science and morality in Nazi Germany The Good Research Guide A non-specialist book for teachers starting out in education research WORTH A LOOK Breakthrough to CLIL for Physics A book based on a physics curriculum for non-English students WEB WATCH Electric cycles online: patterns of use APPS The virtual laboratory advances personal skills

Sensitive and selective spectrophotometric assay of piroxicam in pure form, capsule and human blood serum samples via ion-pair complex formation.

PubMed

Alizadeh, Nina; Keyhanian, Fereshteh

2014-09-15

A simple, accurate and highly sensitive spectrophotometric method has been developed for the rapid determination of piroxicam (PX) in pure and pharmaceutical formulations. The proposed method involves formation of stable yellow colored ion-pair complexes of the amino derivative (basic nitrogen) of PX with three sulphonphthalein acid dyes namely; bromocresol green (BCG), bromothymol blue (BTB), bromophenol blue (BPB) in acidic medium. The colored species exhibited absorption maxima at 438, 429 and 432 nm with molar absorptivity values of 9.400×10(3), 1.218×10(3) and 1.02×10(4) L mol(-1) cm(-1) for PX-BCG, PX-BTB and PX-BPB complexes, respectively. The effect of optimum conditions via acidity, reagent concentration, time and solvent were studied. The reactions were extremely rapid at room temperature and the absorbance values remained constant for 48h. Beer's law was obeyed with a good correlation coefficient in the concentration ranges 1-100 μg mL(-1) for BCG, BTB complexes and 1-95 μg mL(-1) for BPB complex. The composition ratio of the ion-pair complexes were found to be 1:1 in all cases as established by Job's method. No interference was observed from common additives and excipients which may be present in the pharmaceutical preparations. The proposed method was successfully applied for the determination of PX in capsule and human blood serum samples with good accuracy and precision. Copyright © 2014 Elsevier B.V. All rights reserved.

Knowledge of and attitude towards road traffic codes among commercial motorcycle riders in Anambra State.

PubMed

Adogu, O U; Ilika, A L

2006-12-01

Road traffic accidents (rtas) represent a major epidemic of non communicable disease in the country and has since escalated with the introduction of the new phenomenon of commercial motorcycle transportation such as is found in the two urban towns of nnewi and Awka of Anambra state, Nigeria. making use of a pre-tested, semi structured, interviewer administered questionnaire, relevant data on socio demographic and motorcycle characteristics were collected from a sample of commercial motorcyclists selected by systematic sampling technique. their knowledge of and attitude towards road traffic and safety codes were elicited. The result showed that the all-male commercial motorcyclists had a mean age of 30+8.9 years. one hundred and seventy six (32.6%) possessed good knowledge of road traffic codes and safety, while 35 (6.5%) exhibited good attitude towards them. both knowledge of and attitude towards traffic codes and safety improved with increase in educational level (p<0.005, p<0.001 respectively). the younger motorcyclists also possessed statistically significant better knowledge of traffic codes than their older counterparts (p<0.025). attitude to traffic codes and safety had no association with age of the motorcyclists (p>0.25). the study has provided useful information on the knowledge of and attitude towards road traffic and safety codes among commercial motorcyclists in nigeria. pursuit of knowledge through formal and informal education should run pari pasu with efforts to improve the nigerian economy in order to ensure a sustainable positive attitudinal change towards road traffic codes and safety among commercial motorcyclists.

Human bony labyrinth is an indicator of population history and dispersal from Africa.

PubMed

Ponce de León, Marcia S; Koesbardiati, Toetik; Weissmann, John David; Milella, Marco; Reyna-Blanco, Carlos S; Suwa, Gen; Kondo, Osamu; Malaspinas, Anna-Sapfo; White, Tim D; Zollikofer, Christoph P E

2018-04-17

The dispersal of modern humans from Africa is now well documented with genetic data that track population history, as well as gene flow between populations. Phenetic skeletal data, such as cranial and pelvic morphologies, also exhibit a dispersal-from-Africa signal, which, however, tends to be blurred by the effects of local adaptation and in vivo phenotypic plasticity, and that is often deteriorated by postmortem damage to skeletal remains. These complexities raise the question of which skeletal structures most effectively track neutral population history. The cavity system of the inner ear (the so-called bony labyrinth) is a good candidate structure for such analyses. It is already fully formed by birth, which minimizes postnatal phenotypic plasticity, and it is generally well preserved in archaeological samples. Here we use morphometric data of the bony labyrinth to show that it is a surprisingly good marker of the global dispersal of modern humans from Africa. Labyrinthine morphology tracks genetic distances and geography in accordance with an isolation-by-distance model with dispersal from Africa. Our data further indicate that the neutral-like pattern of variation is compatible with stabilizing selection on labyrinth morphology. Given the increasingly important role of the petrous bone for ancient DNA recovery from archaeological specimens, we encourage researchers to acquire 3D morphological data of the inner ear structures before any invasive sampling. Such data will constitute an important archive of phenotypic variation in present and past populations, and will permit individual-based genotype-phenotype comparisons. Copyright © 2018 the Author(s). Published by PNAS.

Preparation of three-dimensional mesoporous polymer in situ polymerization solid phase microextraction fiber and its application to the determination of seven chlorophenols.

PubMed

Wang, Xuemei; Wang, Huan; Huang, Pengfei; Ma, Xiaomin; Lu, Xiaoquan; Du, Xinzhen

2017-01-06

A superior solid-phase microextraction (SPME) fiber-coating material, three dimensional order mesoporous polymers with Ia-3d bicontinuous cubic structure (3D-OMPs) was in situ coated on a stainless steel wire by solvent evaporation induced self-assembly (EISA) and thermo-polymerization. Fourier-transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angel X-ray diffraction (SAXRD), N 2 adsorption-desorption transmission, and thermogravimetry analysis (TGA) were applied to the characterization of the synthesized 3D-OMPs coating. The performance and feasibility of the homemade fiber was evaluated through direct immersion (DI) SPME followed by high-performance liquid chromatography-UV detector (HPLC-UV) for the simultaneous extraction of seven chlorophenols in water samples. Under the optimum conditions, the prepared fiber exhibited excellent extraction properties as compared to three commercial fibers, the DI-SPME-HPLC-UV method showed low limits of detection (0.32-1.85μgL -1 ), wide linear ranges (5.0-1000μgL -1 ), and acceptable reproducibility (relative standard deviation, RSD<7.6% for one fiber, RSD<8.9% for fiber to fiber). Moreover, the method was further successfully applied to the analysis of seven CPs in real samples with good recoveries (80.5-99.5%) and satisfactory precisions (RSD<9.2%). It was confirmed that the proposed method has high sensitivity, outstanding selectivity and good reproducibility to the determination of trace CPs in the environmental water. Copyright © 2016 Elsevier B.V. All rights reserved.

Silicon Nitride for Direct Water-Splitting and Corrosion Mitigation

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

Head, J.; Turner, J.A.

2006-01-01

Todays fossil fuels are becoming harder to obtain, creating pollution problems, and posing hazards to people’s health. One alternative to fossil fuels is hydrogen, capable of serving as a clean and efficient energy carrier. Certain semiconductors are able to harness the energy of photons and direct it into water electrolysis in a process known as photoelectrochemical water splitting. Triple junction devices integrate three semiconductors of different band gaps resulting in a monolithic material that absorbs over a broader spectrum. Amorphous silicon (a-Si) is one such material that, when stacked in tandem, possesses water-splitting capabilities. Even though a-Si is capable ofmore » splitting water, it is an unstable material in solution and therefore requires a coating to protect the surface from corrosion. A stable, transparent material that has the potential for corrosion protection is silicon nitride. In this study, silicon nitride thin films were grown using DC magnetron sputtering with varying amounts of argon and nitrogen added to the system. X-ray diffraction indicated amorphous silicon nitride films. Current as a function of potential was determined from cyclic voltammetry measurements. Mott-Schottky analysis showed n-type behavior with absorption and transmission measurements indicated variation in flatband potentials. Variation in band gap values ranging from 1.90 to 4.0 eV. Corrosion measurements reveal that the silicon nitride samples exhibit both p-type and n-type behavior. Photocurrent over a range of potentials was greater in samples that were submerged in acidic electrolyte. Silicon nitride shows good stability in acidic, neutral, and basic solutions, indicative of a good material for corrosion mitigation.« less

Ultrafine Nanocrystalline CeO2@C-Containing NaAlH4 with Fast Kinetics and Good Reversibility for Hydrogen Storage.

PubMed

Zhang, Xin; Liu, Yongfeng; Wang, Ke; Li, You; Gao, Mingxia; Pan, Hongge

2015-12-21

A nanocrystalline CeO2@C-containing NaAlH4 composite is successfully synthesized in situ by hydrogenating a NaH-Al mixture doped with CeO2@C. Compared with NaAlH4 , the as-prepared CeO2@C-containing NaAlH4 composite, with a minor amount of excess Al, exhibits significantly improved hydrogen storage properties. The dehydrogenation onset temperature of the hydrogenated [NaH-Al-7 wt % CeO2@C]-0.04Al sample is 77 °C lower than that of the pristine sample because of a reduced kinetic barrier. More importantly, the dehydrogenated sample absorbs ∼4.7 wt % hydrogen within 35 min at 100°C and 10 MPa of hydrogen. Compositional and structural analyses reveal that CeO2 is converted to CeH2 during ball milling and that the newly formed CeH2 works with the excess of Al to synergistically improve the hydrogen storage properties of NaAlH4. Our findings will aid in the rational design of novel catalyst-doped complex hydride systems with low operating temperatures, fast kinetics, and long-term cyclability. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural morphology of zinc oxide structures with antibacterial application of calamine lotion

NASA Astrophysics Data System (ADS)

Ann, Ling Chuo; Mahmud, Shahrom; Bakhori, Siti Khadijah Mohd; Sirelkhatim, Amna; Mohamad, Dasmawati; Hasan, Habsah; Seeni, Azman; Rahman, Rosliza Abdul

2015-04-01

In this study, we report the structural morphology of a zinc oxide (ZnO) sample and antibacterial application of the ZnO structures in calamine lotion. Antibacterial activities of the calamine lotion towards Staphylococcus aureus and Pseudomonas aeruginosa were investigated. The structural morphology of ZnO sample was studied using a transmission electron microscope (TEM) and a field-emission scanning electron microscope (FESEM). The morphologies of the ZnO structure consisted of many rod and spherical structures. The particle sizes of the sample ranged from 40 nm to 150 nm. A calamine lotion was prepared through mixing the ZnO structures with other constituents in suitable proportion. The energy-dispersive x-ray spectroscopy (EDS) revealed the presence of large amount of ZnO structures whiles the X-ray diffraction (XRD) results showed a good crystalline property of ZnO in the calamine lotion mixture. The morphological structures of ZnO were found to remain unchanged in the calamine lotion mixture through FESEM imaging. In the antibacterial test, prepared calamine lotion exhibited a remarkable bacterial inhibition on Staphylococcus aureus and Pseudomonas aeruginosa after 24 h of treatment. The bactericidal capability of calamine lotion was largely due to the presence of ZnO structures which induce high toxicity and killing effect on the bacteria.

Concurrent profiling of polar metabolites and lipids in human plasma using HILIC-FTMS

NASA Astrophysics Data System (ADS)

Cai, Xiaoming; Li, Ruibin

2016-11-01

Blood plasma is the most popularly used sample matrix for metabolite profiling studies, which aim to achieve global metabolite profiling and biomarker discovery. However, most of the current studies on plasma metabolite profiling focused on either the polar metabolites or lipids. In this study, a comprehensive analysis approach based on HILIC-FTMS was developed to concurrently examine polar metabolites and lipids. The HILIC-FTMS method was developed using mixed standards of polar metabolites and lipids, the separation efficiency of which is better in HILIC mode than in C5 and C18 reversed phase (RP) chromatography. This method exhibits good reproducibility in retention times (CVs < 3.43%) and high mass accuracy (<3.5 ppm). In addition, we found MeOH/ACN/Acetone (1:1:1, v/v/v) as extraction cocktail could achieve desirable gathering of demanded extracts from plasma samples. We further integrated the MeOH/ACN/Acetone extraction with the HILIC-FTMS method for metabolite profiling and smoking-related biomarker discovery in human plasma samples. Heavy smokers could be successfully distinguished from non smokers by univariate and multivariate statistical analysis of the profiling data, and 62 biomarkers for cigarette smoke were found. These results indicate that our concurrent analysis approach could be potentially used for clinical biomarker discovery, metabolite-based diagnosis, etc.

Green synthesized gold nanoparticles decorated graphene oxide for sensitive determination of chloramphenicol in milk, powdered milk, honey and eye drops.

PubMed

Karthik, R; Govindasamy, Mani; Chen, Shen-Ming; Mani, Veerappan; Lou, Bih-Show; Devasenathipathy, Rajkumar; Hou, Yu-Shen; Elangovan, A

2016-08-01

A simple and rapid green synthesis using Bischofia javanica Blume leaves as reducing agent was developed for the preparation of gold nanoparticles (AuNPs). AuNPs decorated graphene oxide (AuNPs/GO) was prepared and employed for the sensitive amperometric determination of chloramphenicol. The green biosynthesis requires less than 40s to reduce gold salts to AuNPs. The formations of AuNPs and AuNPs/GO were evaluated by scanning electron and atomic force microscopies, UV-Visible and energy dispersive X-ray spectroscopies, X-ray diffraction studies, and electrochemical methods. AuNPs/GO composite film modified electrode was fabricated and shown excellent electrocatalytic ability towards chloramphenicol. Under optimal conditions, the amperometric sensing platform has delivered wide linear range of 1.5-2.95μM, low detection limit of 0.25μM and high sensitivity of 3.81μAμM(-1)cm(-2). The developed sensor exhibited good repeatability and reproducibility, anti-interference ability and long-term storage stability. Practical feasibility of the sensor has been demonstrated in food samples (milk, powdered milk and honey) and pharmaceutical sample (eye drops). The green synthesized AuNPs/GO composite has great potential for analysis of food samples in food safety measures. Copyright © 2016 Elsevier Inc. All rights reserved.

Enhanced photovoltaic performance of dye sensitized solar cell using SnO2 nanoflowers

NASA Astrophysics Data System (ADS)

Arote, Sandeep A.; Tabhane, Vilas A.; Pathan, Habib M.

2018-01-01

The study highlighted enhanced performance of SnO2 based DSSC using photoanode with nanostructured morphology. The simple organic surfactant free hydrothermal synthesis method was used for preparation of SnO2 nanoflowers for dye sensitized solar cell (DSSC) application. The hydrothermal reaction time was varied to obtain different SnO2 nanostructures. The hydrothermal reaction time showed considerable effect on optical and structural properties of the prepared samples. The results indicated that the prepared samples were pure rutile SnO2. The band gap of prepared samples was greater than bulk SnO2 and varied from 3.64 to 3.81 eV with increase in hydrothermal reaction time. With increase in reaction time from 4 to 24 h, the microstructure of SnO2 changed from agglomerated nanoparticles to nanopetals and finally to self-assembled nanoflowers. Flower-like SnO2 nanostructures showed size around 300-700 nm, and composed of large numbers of 3 dimensional petals connected with each other forming 3D nanoflowers by self-assembly. Consequently, the DSSC with flower-like SnO2 nanostructures exhibited good photovoltaic performance with Voc, Jsc and η about 0.43 V, 4.36 mA/cm2 and 1.11%, respectively.

Luminescent LuVO4:Ln3+ (Ln = Eu, Sm, Dy, Er) hollow porous spheres for encapsulation of biomolecules

NASA Astrophysics Data System (ADS)

Li, Dan; Liu, Chunlei; Jiang, Lianzhou

2015-10-01

In this study, LuVO4:Ln3+ (Ln = Eu, Sm, Dy, Er) hollow porous spheres, synthesized via self-sacrificing templated route, are developed for enzyme immobilization and protein adsorption. The four LuVO4 hollow spheres with diameter of 180 nm, 280 nm, 370 nm and 480 nm were obtained. The size of LuVO4 hollow sphere is dependent on Lu(OH)CO3 template. Upon excitation by UV light, hollow LuVO4:Ln3+ (Ln = Eu, Sm, Dy, Er) spheres exhibit red (Eu3+), orange (Sm3+), yellow-green (Dy3+), and green (Er3+) emissions. The good biocompatibility of sample is validated by MTT assay. Due to structure feature and size of obtained sample, the rapid encapsulation of biomolecules within samples has been achieved. Furthermore, the hollow spheres show different biomolecules adsorption capacities at different buffer solution pH values. The release behaviors of two kinds of biomolecules (lysozyme and bovine serum albumin) are also investigated. LuVO4 hollow spheres are suitable carriers for biomolecules. The emission intensity of Eu3+ in the LuVO4:Eu3+ varies with the released amount of LYZ. This enables the monitoring of release process by the change in the luminescence intensity.

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.

Processing, Mechanical and Optical Properties of Additive-Free ZrC Ceramics Prepared by Spark Plasma Sintering

PubMed Central

Musa, Clara; Licheri, Roberta; Orrù, Roberto; Cao, Giacomo; Sciti, Diletta; Silvestroni, Laura; Zoli, Luca; Balbo, Andrea; Mercatelli, Luca; Meucci, Marco; Sani, Elisa

2016-01-01

In the present study, nearly fully dense monolithic ZrC samples are produced and broadly characterized from microstructural, mechanical and optical points of view. Specifically, 98% dense products are obtained by Spark Plasma Sintering (SPS) after 20 min dwell time at 1850 °C starting from powders preliminarily prepared by Self-propagating High-temperature Synthesis (SHS) followed by 20 min ball milling. A prolonged mechanical treatment up to 2 h of SHS powders does not lead to appreciable benefits. Vickers hardness of the resulting samples (17.5 ± 0.4 GPa) is reasonably good for monolithic ceramics, but the mechanical strength (about 250 MPa up to 1000 °C) could be further improved by suitable optimization of the starting powder characteristics. The very smoothly polished ZrC specimen subjected to optical measurements displays high absorption in the visible-near infrared region and low thermal emittance at longer wavelengths. Moreover, the sample exhibits goodspectral selectivity (2.1–2.4) in the 1000–1400 K temperature range. These preliminary results suggest that ZrC ceramics produced through the two-step SHS/SPS processing route can be considered as attractive reference materials for the development of innovative solar energy absorbers. PMID:28773611

Vortex-assisted surfactant-enhanced emulsification microextraction based on solidification of floating organic drop combined with high performance liquid chromatography for determination of naproxen and nabumetone.

PubMed

Asadi, Mohammad; Haji Shabani, Ali Mohammad; Dadfarnia, Shayessteh; Abbasi, Bijan

2015-12-18

A novel, rapid, simple and green vortex-assisted surfactant-enhanced emulsification microextraction method based on solidification of floating organic drop was developed for simultaneous separation/preconcentration and determination of ultra trace amounts of naproxen and nabumetone with high performance liquid chromatography-fluorescence detection. Some parameters influencing the extraction efficiency of analytes such as type and volume of extractant, type and concentration of surfactant, sample pH, KCl concentration, sample volume, and vortex time were investigated and optimized. Under optimal conditions, the calibration graph exhibited linearity in the range of 3.0-300.0ngL(-1) for naproxen and 7.0-300.0ngL(-1) for nabumetone with a good coefficient of determination (R(2)>0.999). The limits of detection were 0.9 and 2.1ngL(-1). The relative standard deviations for inter- and intra-day assays were in the range of 5.8-10.1% and 3.8-6.1%, respectively. The method was applied to the determination of naproxen and nabumetone in urine, water, wastewater and milk samples and the accuracy was evaluated through recovery experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

Health education in school children.

PubMed

Tragler, A

1991-05-01

A researcher compared responses to a pretest questionnaire with those a posttest questionnaire completed by 304 12-16 year old school children in India to assess health knowledge of school children. The children attended either a public school or a private school in Bombay or a rural school in Kazli operated by a charitable institution. The researcher administered the posttest 4 weeks after health education talks and demonstrations. Before the health education course, children at all 3 schools had limited health knowledge. For example, 19-52% of the children exhibited poor knowledge and only 2% exhibited good knowledge (all from the public school). After undergoing health education, 52% of the children in the public school had good knowledge and 37% had very good knowledge. These parallel figures for the private and rural schools were 67% and 23% and 76% respectively. Nutrition knowledge was considerably better than knowledge of immunization and hygiene before the health education course. 6% of the students at the private school had good knowledge of nutrition compared to only 2% for immunization and 1% for hygiene. Nutrition knowledge did increase after health education, but not as markedly as did immunization knowledge. For example, good and very good immunization knowledge was 60% for the public school, 76% for the private school, and 97% for the rural school compared to 0-3% prior to health education. Moreover health education cast away most of the misconceptions about the cause of worm infections and tetanus, the ability to beet roots to improve blood quality, and the ability of milk to sustain a health life during the 1st year.

Low Cost Fiber Optic Cable Assemblies for Local Distribution Systems

DTIC Science & Technology

1977-04-01

coefficient of friction, and is chemically inert. PFA exhibits low water permeability and ab- sorption . FEP-100 and FEP-110 were initially extruded over T08...with FEP 110. To overcome these problems, Teflon PFA 9704 was evaluated. It exhibited good extrudability which allowed application of thin and thick...superior extrudability, in addition to meeting the optical characteristics required for a cladding material, Teflon PFA was considered a viable

Precursors to radiopharmaceutical agents for tissue imaging

DOEpatents

Srivastava, Prem C.; Knapp, Jr., Furn F.

1988-01-01

A class of radiolabeled compounds to be used in tissue imaging that exhibits rapid brain uptake, good brain:blood radioactivity ratios, and long retention times. The imaging agents are more specifically radioiodinated aromatic amines attached to dihydropyridine carriers, that exhibit heart as well as brain specificity. In addition to the radiolabeled compounds, classes of compounds are also described that are used as precursors and intermediates in the preparation of the imaging agents.

Tetrakis-amido high flux membranes

DOEpatents

McCray, S.B.

1989-10-24

Composite RO membranes of a microporous polymeric support and a polyamide reaction product of a tetrakis-aminomethyl compound and a polyacylhalide are disclosed, said membranes exhibiting high flux and good chlorine resistance.

Tetrakis-amido high flux membranes

DOEpatents

McCray, Scott B.

1989-01-01

Composite RO membranes of a microporous polymeric support and a polyamide reaction product of a tetrakis-aminomethyl compound and a polyacylhalide are disclosed, said membranes exhibiting high flux and good chlorine resistance.

Antibacterial activity of Hygrophila stricta and Peperomia pellucida.

PubMed

Khan, M R; Omoloso, A D

2002-06-01

The crude methanolic extracts of Hygrophila scricta and Peperomia pellucida were fractionated into petrol, dichloromethane, ethyl acetate and butanol. All the crude extracts and the fractions exhibited a very good level of broad spectrum antibacterial activity. The fractions were more active than the crude extracts. The petrol fraction of H. stricta and the butanol fraction of P. pellucida were particularly good. No activity was noticed for the moulds tested.