Headspace versus direct immersion solid phase microextraction in complex matrixes: investigation of analyte behavior in multicomponent mixtures.

PubMed

Gionfriddo, Emanuela; Souza-Silva, Érica A; Pawliszyn, Janusz

2015-08-18

This work aims to investigate the behavior of analytes in complex mixtures and matrixes with the use of solid-phase microextraction (SPME). Various factors that influence analyte uptake such as coating chemistry, extraction mode, the physicochemical properties of analytes, and matrix complexity were considered. At first, an aqueous system containing analytes bearing different hydrophobicities, molecular weights, and chemical functionalities was investigated by using commercially available liquid and solid porous coatings. The differences in the mass transfer mechanisms resulted in a more pronounced occurrence of coating saturation in headspace mode. Contrariwise, direct immersion extraction minimizes the occurrence of artifacts related to coating saturation and provides enhanced extraction of polar compounds. In addition, matrix-compatible PDMS-modified solid coatings, characterized by a new morphology that avoids coating fouling, were compared to their nonmodified analogues. The obtained results indicate that PDMS-modified coatings reduce artifacts associated with coating saturation, even in headspace mode. This factor, coupled to their matrix compatibility, make the use of direct SPME very practical as a quantification approach and the best choice for metabolomics studies where wide coverage is intended. To further understand the influence on analyte uptake on a system where additional interactions occur due to matrix components, ex vivo and in vivo sampling conditions were simulated using a starch matrix model, with the aim of mimicking plant-derived materials. Our results corroborate the fact that matrix handling can affect analyte/matrix equilibria, with consequent release of high concentrations of previously bound hydrophobic compounds, potentially leading to coating saturation. Direct immersion SPME limited the occurrence of the artifacts, which confirms the suitability of SPME for in vivo applications. These findings shed light into the implementation of in vivo SPME strategies in quantitative metabolomics studies of complex plant-based systems.

Reactive Fabrication and Effect of NbC on Microstructure and Tribological Properties of CrS Co-Based Self-Lubricating Coatings by Laser Cladding.

PubMed

Fang, Liuyang; Yan, Hua; Yao, Yansong; Zhang, Peilei; Gao, Qiushi; Qin, Yang

2017-12-28

The CrS/NbC Co-based self-lubricating composite coatings were successfully fabricated on Cr12MoV steel surface by laser clad Stellite 6, WS₂, and NbC mixed powders. The phase composition, microstructure, and tribological properties of the coatings ware investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS), as well as dry sliding wear testing. Based on the experimental results, it was found reactions between WS₂ and Co-based alloy powder had occurred, which generated solid-lubricant phase CrS, and NbC play a key role in improving CrS nuclear and refining microstructure of Co-based composite coating during laser cladding processing. The coatings were mainly composed of γ-Co, CrS, NbC, Cr 23 C₆, and CoC x . Due to the distribution of the relatively hard phase of NbC and the solid lubricating phase CrS, the coatings had better wear resistance. Moreover, the suitable balance of CrS and NbC was favorable for further decreasing the friction and improving the stability of the contact surfaces between the WC ball and the coatings. The microhardness, friction coefficient, and wear rate of the coating 4 (Clad powders composed of 60 wt % Stellite 6, 30 wt % NbC and 10 wt % WS₂) were 587.3 HV 0.5 , 0.426, and 5.61 × 10 -5 mm³/N·m, respectively.

Inorganic-organic hybrid coating material for the online in-tube solid-phase microextraction of monohydroxy polycyclic aromatic hydrocarbons in urine.

PubMed

Wang, ShuLing; Xu, Hui

2016-12-01

An inorganic-organic hybrid nanocomposite (zinc oxide/polypyrrole) that represents a novel kind of coating for in-tube solid-phase microextraction is reported. The composite coating was prepared by a facile electrochemical polymerization strategy on the inner surface of a stainless-steel tube. Based on the coated tube, a novel online in-tube solid-phase microextraction with liquid chromatography and mass spectrometry method was developed and applied for the extraction of three monohydroxy polycyclic aromatic hydrocarbons in human urine. The coating displayed good extraction ability toward monohydroxy polycyclic aromatic hydrocarbons. In addition, long lifespan, excellent stability, and good compression resistance were also obtained for the coating. The experimental conditions affecting the extraction were optimized systematically. Under the optimal conditions, the limits of detection and quantification were in the range of 0.039-0.050 and 0.130-0.167 ng/mL, respectively. Good linearity (0.2-100 ng/mL) was obtained with correlation coefficients larger than 0.9967. The repeatability, expressed as relative standard deviation, ranged between 2.5% and 9.4%. The method offered the advantage of process simplicity, rapidity, automation, and sensitivity in the analysis of human urinary monohydroxy polycyclic aromatic hydrocarbons in two different cities of Hubei province. An acceptable recovery of monohydroxy polycyclic aromatic hydrocarbons (64-122%) represented the additional attractive features of the method in real urine analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid in situ growth of oriented titanium-nickel oxide composite nanotubes arrays coated on a nitinol wire as a solid-phase microextraction fiber coupled to HPLC-UV.

PubMed

Zhen, Qi; Zhang, Min; Song, Wenlan; Wang, Huiju; Wang, Xuemei; Du, Xinzhen

2016-10-01

An oriented titanium-nickel oxide composite nanotubes coating was in situ grown on a nitinol wire by direct electrochemical anodization in ethylene glycol with ammonium fluoride and water for the first time. The morphology and composition of the resulting coating showed that the anodized nitinol wire provided a titania-rich coating. The titanium-nickel oxide composite nanotubes coated fiber was used for solid-phase microextraction of different aromatic compounds coupled to high-performance liquid chromatography with UV detection. The titanium-nickel oxide composite nanotubes coating exhibited high extraction capability, good selectivity, and rapid mass transfer for weakly polar UV filters. Thereafter the important parameters affecting extraction efficiency were investigated for solid-phase microextraction of UV filters. Under the optimized conditions, the calibration curves were linear in the range of 0.1-300 μg/L for target UV filters with limits of detection of 0.019-0.082 μg/L. The intraday and interday precision of the proposed method with the single fiber were 5.3-7.2 and 5.9-7.9%, respectively, and the fiber-to-fiber reproducibility ranged from 6.3 to 8.9% for four fibers fabricated in different batches. Finally, its applicability was evaluated by the extraction and determination of target UV filters in environmental water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel benzo-15-crown-5 sol-gel coating for solid-phase microextraction.

PubMed

Wang, Danhua; Xing, Jun; Peng, Jiagang; Wu, Caiying

2003-07-11

A novel dihydroxy-terminated benzo-15-crown-5 was synthesized and applied to prepare a solid-phase microextraction (SPME) fiber coating with sol-gel technology. The optimization of the sol-gel process was studied. The coating method with sol-gel was improved and completed in one run, which economized materials and allowed easier control of the fiber thickness. The repeatability of coating fiber to fiber was better than 4.94% (RSD). The surface of the fiber coating was well-distributed and an electron microscopy experiment suggested a porous structure for crown ether coating, providing high surface areas and allowing for high extraction efficiency. The coating has a high thermal stability (350 degrees C), long lifetime and can stand solvent (organic and inorganic) rinsing due to the chemical binding between the coating and the fiber surface. Non-polar benzene, toluene, ethylbenzene, xylenes, chlorobenzenes, polar phenolic compounds and arylamines were used to evaluate the character of the fiber coating by headspace SPME-gas chromatography technology. For phenols, the linear concentrations ranged from 5 to 1000 microg/l, the detection limits were between 0.05 and 1 microg/l, and the RSD was less than 5%. The addition of benzo-crown ether not only increases the thermal stability of the fiber coating, but also enhances the selectivity of the fiber coating. Compared with commercially available SPME fibers poly(dimethylsiloxane) and polyacrylate, the few phases showed better selectivity and sensitivity towards non-polar and polar aromatic compounds.

A star-shaped polythiophene dendrimer coating for solid-phase microextraction of triazole agrochemicals.

PubMed

Abolghasemi, Mir Mahdi; Habibiyan, Rahim; Jaymand, Mehdi; Piryaei, Marzieh

2018-02-14

A nanostructured star-shaped polythiophene dendrimer was prepared and used as a fiber coating for headspace solid phase microextraction of selected triazolic pesticides (tebuconazole, hexaconazole, penconazole, diniconazole, difenoconazole, triticonazole) from water samples. The dendrimer with its large surface area was characterized by thermogravimetric analysis, UV-Vis spectroscopy and field emission scanning electron microscopy. It was placed on a stainless steel wire for use in SPME. The experimental conditions for fiber coating, extraction, stirring rate, ionic strength, pH value, desorption temperature and time were optimized. Following thermal desorption, the pesticides were quantified by GC-MS. Under optimum conditions, the repeatability (RSD) for one fiber (for n = 3) ranges from 4.3 to 5.6%. The detection limits are between 8 and 12 pg mL -1 . The method is fast, inexpensive (in terms of equipment), and the fiber has high thermal stability. Graphical abstract Schematic presentation of a nanostructured star-shaped polythiophene dendrimer for use in headspace solid phase microextraction of the triazolic pesticides (tebuconazole, hexaconazole, penconazole, diniconazole, difenoconazole, triticonazole). They were then quantified by gas chromatography-mass spectrometry.

Simple fabrication of solid phase microextraction fiber employing nitrogen-doped ordered mesoporous polymer by in situ polymerization.

PubMed

Zheng, Juan; Liang, Yeru; Liu, Shuqin; Jiang, Ruifen; Zhu, Fang; Wu, Dingcai; Ouyang, Gangfeng

2016-01-04

A combination of nitrogen-doped ordered mesoporous polymer (NOMP) and stainless steel wires led to highly sensitive, selective, and stable solid phase microextraction (SPME) fibers by in situ polymerization for the first time. The ordered structure of synthesized NOMP coating was illustrated by transmission electron microscopy (TEM) and X-ray diffraction (XRD), and microscopy analysis by scanning electron microscopy (SEM) confirmed a homogenous morphology of the NOMP-coated fiber. The NOMP-coated fiber was further applied for the extraction of organochlorine pesticides (OCPs) with direct-immersion solid-phase microextraction (DI-SPME) method followed by gas chromatography-mass spectrometry (GC-MS) quantification. Under the optimized conditions, low detection limits (0.023-0.77 ng L(-1)), a wide linear range (9-1500 ng L(-1)), good repeatability (3.5-8.1%, n=6) and excellent reproducibility (1.5-8.3%, n=3) were achieved. Moreover, the practical feasibility of the proposed method was evaluated by determining OCPs in environmental water samples with satisfactory recoveries. Copyright © 2015 Elsevier B.V. All rights reserved.

Silica aerogel coated on metallic wire by phase separation of polystyrene for in-tube solid phase microextraction.

PubMed

Baktash, Mohammad Yahya; Bagheri, Habib

2017-06-02

In this research, an attempt was made toward synthesizing a sol-gel-based silica aerogel and its subsequent coating on a copper wire by phase separation of polystyrene. Adaption of this new approach enabled us to coat the metallic wire with powder materials. The use of this method for coating, led to the formation of a porous and thick structure of silica aerogel. The coated wire was placed in a needle and used as the sorbent for in-tube solid phase microextraction of chlorobenzenes (CBs). The superhydrophobicity of sorbent on extraction efficiency was investigated by using different ratios of tetraethylorthosilicate/methyltrimethoxysilane. The surface coated with the prepared silica aerogel by the phase separation of polystyrene showed high contact angle, approving the desired superhydrophobic properties. Effects of major parameters influencing the extraction efficiency including the extraction temperature, extraction time, ionic strength, desorption time were investigated and optimized. The limits of detection and quantification of the method under the optimized condition were 0.1-1.2 and 0.4-4.1ngL -1 , respectively. The relative standard deviations (RSD%) at a concentration level of 10ngL -1 were between 4 and 10% (n=3). The calibration curves of CBs showed linearity from 1 to100ngL -1 . Eventually, the method was successfully applied to the extraction of model compounds from real water samples and relative recoveries varied from 88 to 115%. Copyright © 2017 Elsevier B.V. All rights reserved.

Highly porous solid-phase microextraction fiber coating based on poly(ethylene glycol)-modified ormosils synthesized by sol-gel technology.

PubMed

da Costa Silva, Raquel Gomes; Augusto, Fabio

2005-04-22

The preparation and characteristics of solid-phase microextraction (SPME) fibers coated with Carbowax 20M ormosil (organically modified silica) are described here. Raw fused silica fibers were coated with Carbowax 20M-modified silica using sol-gel process. Scanning electron micrographs of fibers revealed a highly porous, sponge-like coating with an average thickness of (8 +/- 1) microm. The sol-gel Carbowax fibers were compared to commercial fibers coated with 100 microm polydimethylsiloxane (PDMS) and 65 microm Carbowax-divinylbenzene (DVB). Shorter equilibrium times were possible with the sol-gel Carbowax fiber: for headspace extraction of the test analytes, they ranged from less than 3 min for benzene to 15 min for o-xylene. Extraction efficiencies of the sol-gel Carbowax fiber were superior to those of conventional fibers: for o-xylene, the extracted masses were 230 and 540% of that obtained with 100 microm PDMS and 65 microm Carbowax-DVB fibers, respectively.

[Preparation of a novel activated carbon coating fiber for solid phase micro-extraction and its application for halocarbon compound analysis in water].

PubMed

Wang, Shutao; Wang, Yan; You, Hong; Liang, Zhihua

2004-09-01

A novel activated carbon coating fiber used for solid phase micro-extraction (SPME) was prepared using activated carbon powder and silica resin adhesive. The extraction properties of the novel activated carbon coating fiber were investigated. The results indicate that this coating fiber has high concentration ability, with enrichment factors for chloroform, carbon tetrachloride, trichloroethylene and tetrachloroethylene in the range of 13.8 to 18.7. The fiber is stable at temperature as high as 290 degrees C and it can be used for over 140 times at 250 degrees C. The activated carbon coating fiber was then applied to the analysis of the four halocarbon compounds mentioned above. A linear correlation with correlation coefficients between 0.995 2 and 0.999 4 and the detection limits between 0.008 and 0.05 microg/L were observed. The method was also applied to a real water sample analysis and the recoveries of these halocarbon compounds were from 95.5% to 104.6%.

Preparation of solid-phase microextraction fibers by in-mold coating strategy for derivatization analysis of 24-epibrassinolide in pollen samples.

PubMed

Pan, Jialiang; Hu, Yuling; Liang, Tingan; Li, Gongke

2012-11-02

A novel and simple in-mold coating strategy was proposed for the preparation of uniform solid-phase microextraction (SPME) coatings. Such a strategy is based on the direct synthesis of the polymer coating on the surface of a solid fiber using a glass capillary as the mold. The capillary was removed and the polymer with well-controlled thickness could be coated on the silica fiber reproductively. Following the strategy, a new poly(acrylamide-co-ethylene glycol dimethacrylate) (poly(AM-co-EGDMA)) coating was prepared for the preconcentration of 24-epibrassinolide (24-epiBL) from plant matrix. The coating had the enrichment factor of 32 folds, and the extraction efficiency per unit thickness was 5 times higher than that of the commercial polydimethylsiloxane/divinylbenzene (PDMS/DVB) coating. A novel method based on SPME coupled with derivatization and large volume injection-high performance liquid chromatography (LVI-HPLC) was developed for the analysis of 24-epiBL. The linear range was 0.500-20.0 μg/L with the detection limit of 0.13 μg/L. The amounts of endogenous 24-epiBL in rape and sunflower breaking-wall pollens samples were determined with satisfactory recovery (77.8-104%) and reproducibility (3.9-7.9%). The SPME-DE/LVI-HPLC method is rapid, reliable, convenient and applicable for complicated plant samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Reactive Fabrication and Effect of NbC on Microstructure and Tribological Properties of CrS Co-Based Self-Lubricating Coatings by Laser Cladding

PubMed Central

Fang, Liuyang; Yan, Hua; Yao, Yansong; Zhang, Peilei; Gao, Qiushi; Qin, Yang

2017-01-01

The CrS/NbC Co-based self-lubricating composite coatings were successfully fabricated on Cr12MoV steel surface by laser clad Stellite 6, WS2, and NbC mixed powders. The phase composition, microstructure, and tribological properties of the coatings ware investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS), as well as dry sliding wear testing. Based on the experimental results, it was found reactions between WS2 and Co-based alloy powder had occurred, which generated solid-lubricant phase CrS, and NbC play a key role in improving CrS nuclear and refining microstructure of Co-based composite coating during laser cladding processing. The coatings were mainly composed of γ-Co, CrS, NbC, Cr23C6, and CoCx. Due to the distribution of the relatively hard phase of NbC and the solid lubricating phase CrS, the coatings had better wear resistance. Moreover, the suitable balance of CrS and NbC was favorable for further decreasing the friction and improving the stability of the contact surfaces between the WC ball and the coatings. The microhardness, friction coefficient, and wear rate of the coating 4 (Clad powders composed of 60 wt % Stellite 6, 30 wt % NbC and 10 wt % WS2) were 587.3 HV0.5, 0.426, and 5.61 × 10−5 mm3/N·m, respectively. PMID:29283411

A sol-gel based solid phase microextraction fiber for the analysis of aliphatic alcohols in apple juices.

PubMed

Farhadi, Khalil; Maleki, Ramin; Tahmasebi, Raheleh

2010-01-01

A new fiber based on titania-chitin sol-gel coated on a silver wire for the headspace solid phase microextraction of aliphatic alcohols from apple juice samples was developed. The influences of fiber coating composition and microextraction conditions (extraction temperature, extraction time, and ionic strength of the sample matrix) on the fiber performance were investigated. Also, the influence of temperature and time on desorption of analytes from fiber were studied. Under the optimized conditions, a porous fiber with a high extraction capacity and good thermal stability (up to 250 degrees C) was obtained. The proposed headspace solid-phase microextraction-GC method was successfully used for the analysis of aliphatic alcohols in apple juice and concentrate samples. The recovery values were from 92.8 to 98.6%. The RSD (n=5) for all analytes were below 7.8%.

Porous protective solid phase micro-extractor sheath

DOEpatents

Andresen, Brian D.; Randich, Erik

2005-03-29

A porous protective sheath for active extraction media used in solid phase microextraction (SPME). The sheath permits exposure of the media to the environment without the necessity of extending a fragile coated fiber from a protective tube or needle. Subsequently, the sheath can pierce and seal with GC-MS septums, allowing direct injection of samples into inlet ports of analytical equipment. Use of the porous protective sheath, within which the active extraction media is contained, mitigates the problems of: 1) fiber breakage while the fiber is extended during sampling, 2) active media coating loss caused by physical contact of the bare fiber with the sampling environment; and 3) coating slough-off during fiber extension and retraction operations caused by rubbing action between the fiber and protective needle or tube.

A Simple and Selective Fluorescent Sensor Chip for Indole-3-Butyric Acid in Mung Bean Sprouts Based on Molecularly Imprinted Polymer Coatings

PubMed Central

Chang, Jiahua; Bahethan, Bota; Muhammad, Turghun; Yakup, Burabiye; Abbas, Mamatimin

2017-01-01

In this paper, we report the preparation of molecularly imprinted polymer coatings on quartz chips for selective solid-phase microextraction and fluorescence sensing of the auxin, indole-3-butyric acid. The multiple copolymerization method was used to prepare polymer coatings on silylated quartz chips. The polymer preparation conditions (e.g., the solvent, monomer, and cross-linker) were investigated systemically to enhance the binding performance of the imprinted coatings. Direct solid-phase fluorescence measurements on the chips facilitated monitoring changes in coating performance. The average binding capacity of an imprinted polymer coated chip was approximately 152.9 µg, which was higher than that of a non-imprinted polymer coated chip (60.8 µg); the imprinted coatings showed the highest binding to IBA among the structural analogues, indicating that the coatings possess high selectivity toward the template molecule. The developed method was used for the determination of the auxin in mung bean extraction, and the recovery was found to be in the range of 91.5% to 97.5%, with an RSD (n = 3) of less than 7.4%. Thus, the present study provides a simple method for fabricating a fluorescent sensor chip for selective analysis. PMID:28837081

Metal-organic frameworks for analytical chemistry: from sample collection to chromatographic separation.

PubMed

Gu, Zhi-Yuan; Yang, Cheng-Xiong; Chang, Na; Yan, Xiu-Ping

2012-05-15

In modern analytical chemistry researchers pursue novel materials to meet analytical challenges such as improvements in sensitivity, selectivity, and detection limit. Metal-organic frameworks (MOFs) are an emerging class of microporous materials, and their unusual properties such as high surface area, good thermal stability, uniform structured nanoscale cavities, and the availability of in-pore functionality and outer-surface modification are attractive for diverse analytical applications. This Account summarizes our research on the analytical applications of MOFs ranging from sampling to chromatographic separation. MOFs have been either directly used or engineered to meet the demands of various analytical applications. Bulk MOFs with microsized crystals are convenient sorbents for direct application to in-field sampling and solid-phase extraction. Quartz tubes packed with MOF-5 have shown excellent stability, adsorption efficiency, and reproducibility for in-field sampling and trapping of atmospheric formaldehyde. The 2D copper(II) isonicotinate packed microcolumn has demonstrated large enhancement factors and good shape- and size-selectivity when applied to on-line solid-phase extraction of polycyclic aromatic hydrocarbons in water samples. We have explored the molecular sieving effect of MOFs for the efficient enrichment of peptides with simultaneous exclusion of proteins from biological fluids. These results show promise for the future of MOFs in peptidomics research. Moreover, nanosized MOFs and engineered thin films of MOFs are promising materials as novel coatings for solid-phase microextraction. We have developed an in situ hydrothermal growth approach to fabricate thin films of MOF-199 on etched stainless steel wire for solid-phase microextraction of volatile benzene homologues with large enhancement factors and wide linearity. Their high thermal stability and easy-to-engineer nanocrystals make MOFs attractive as new stationary phases to fabricate MOF-coated capillaries for high-resolution gas chromatography (GC). We have explored a dynamic coating approach to fabricate a MOF-coated capillary for the GC separation of important raw chemicals and persistent organic pollutants with high resolution and excellent selectivity. We have combined a MOF-coated fiber for solid-phase microextraction with a MOF-coated capillary for GC separation, which provides an effective MOF-based tandem molecular sieve platform for selective microextraction and high-resolution GC separation of target analytes in complex samples. Microsized MOFs with good solvent stability are attractive stationary phases for high-performance liquid chromatography (HPLC). These materials have shown high resolution and good selectivity and reproducibility in both the normal-phase HPLC separation of fullerenes and substituted aromatics on MIL-101 packed columns and position isomers on a MIL-53(Al) packed column and the reversed-phase HPLC separation of a wide range of analytes from nonpolar to polar and acidic to basic solutes. Despite the above achievements, further exploration of MOFs in analytical chemistry is needed. Especially, analytical application-oriented engineering of MOFs is imperative for specific applications.

Utilizing thin-film solid-phase extraction to assess the effect of organic carbon amendments on the bioavailability of DDT and dieldrin to earthworms

USDA-ARS?s Scientific Manuscript database

Improved approaches are needed to rapidly and accurately assess the bioavailability of persistent, hydrophobic organic compounds in soils at contaminated sites. The performance of a thin-film solid-phase extraction (TF-SPE) assay using vials coated with ethylene vinyl acetate polymer was compared to...

Preparation of sulfonated graphene/polypyrrole solid-phase microextraction coating by in situ electrochemical polymerization for analysis of trace terpenes.

PubMed

Zhang, Chengjiang; Zhang, Zhuomin; Li, Gongke

2014-06-13

In this study, a novel sulfonated graphene/polypyrrole (SG/PPy) solid-phase microextraction (SPME) coating was prepared and fabricated on a stainless-steel wire by a one-step in situ electrochemical polymerization method. Crucial preparation conditions were optimized as polymerization time of 15min and SG doping amount of 1.5mg/mL. SG/PPy coating showed excellent thermal stability and mechanical durability with a long lifespan of more than 200 stable replicate extractions. SG/PPy coating demonstrated higher extraction selectivity and capacity to volatile terpenes than commonly-used commercial coatings. Finally, SG/PPy coating was practically applied for the analysis of volatile components from star anise and fennel samples. The majority of volatile components identified were terpenes, which suggested the ultra-high extraction selectivity of SG/PPy coating to terpenes during real analytical projects. Four typical volatile terpenes were further quantified to be 0.2-27.4μg/g from star anise samples with good recoveries of 76.4-97.8% and 0.1-1.6μg/g from fennel samples with good recoveries of 80.0-93.1%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermal insulating coating for spacecrafts

NASA Technical Reports Server (NTRS)

Kaul, Raj K. (Inventor)

2005-01-01

To protect spacecraft and their contents from excessive heat thermal protection systems are essential. For such thermal protection, metal coatings, ceramic materials, ablative materials, and various matrix materials have all been tried, but none have been found entirely satisfactory. The basis for this thermal protection system is the fact that the heat required to melt a substance is 80 to 100 times larger than the heat required to raise its temperature one degree. This led to the use herein of solid-liquid phase change materials. Unlike conventional heat storage materials, when phase change materials reach the temperature at which they change phase they absorb large amounts of heat without getting hotter. By this invention, then, a coating composition is provided for application to substrates subjected to temperatures above 100? F. The coating composition includes a phase change material.

Thermal Insulating Coating for Spacecrafts

NASA Technical Reports Server (NTRS)

Kaul, Raj K. (Inventor)

2005-01-01

To protect spacecraft and their contents from excessive heat thermal protection system are essential. For such thermal protection, metal coatings, ceramic materials, ablative materials, and various matrix materials have all been tried, but none have been found entirely satisfactory. The basis for this thermal protection system is the fact that the heat required to melt a substance is 80 to 100 times larger than the heat required to raise its temperature one degree. This led to the use herein of solid-liquid phase change materials. Unlike conventional heat storage materials, when phase change materials reach the temperature at which they change phase they absorb large amounts of heat without getting hotter. By this invention, then, a coating composition is provided for application to substrates subjected to temperatures above 100 F. The coating composition includes a phase change material.

Effects of heat treatment on microstructure and mechanical properties of Ni60/h-BN self-lubricating anti-wear composite coatings on 304 stainless steel by laser cladding

NASA Astrophysics Data System (ADS)

Lu, Xiao-Long; Liu, Xiu-Bo; Yu, Peng-Cheng; Zhai, Yong-Jie; Qiao, Shi-Jie; Wang, Ming-Di; Wang, Yong-Guang; Chen, Yao

2015-11-01

Laser clad Ni60/h-BN self-lubricating anti-wear composite coating on 304 stainless steel were heat treated at 600 °C (stress relief annealing) for 1 h and 2 h, respectively. Effects of the phase compositions, microstructure, microhardness, nano-indentation and tribological properties of the composite coatings with and without heat treatment had been investigated systemically. Results indicated that three coatings mainly consist of the matrix γ-(Ni, Fe) solid solution, the CrB ceramic phases and the h-BN lubricating phases. The maximum microhardness of the coatings was first increased from 667.7 HV0.5 to 765.0 HV0.5 after heat treatment for 1 h, and then decreased to 698.3 HV0.5 after heat treatment for 2 h. The hardness of γ-(Ni, Fe) solid solution without heat treatment and after heat treatment 1 h and 2 h were 5.09 GPa, 7.20 GPa and 3.77 GPa, respectively. Compared with the coating without heat treatment, the friction coefficients of the coating after heat treatment were decreased obviously. Effects of the heat treatment time on friction coefficient were negligible, but were significant on wear volume loss. Comparatively speaking, the laser clad self-lubricating anti-wear composite coating after heat treatment for 1 h presented the best anti-wear and friction reduction properties.

Simultaneous determination of polycyclic aromatic hydrocarbons and their chlorination by-products in drinking water and the coatings of water pipes by automated solid-phase microextraction followed by gas chromatography-mass spectrometry.

PubMed

Tillner, Jocelyn; Hollard, Caroline; Bach, Cristina; Rosin, Christophe; Munoz, Jean-François; Dauchy, Xavier

2013-11-08

In this study, an automated method for the simultaneous determination of polycyclic aromatic hydrocarbons (PAHs) and their chlorination by-products in drinking water was developed based on online solid-phase microextraction-gas chromatography-mass spectrometry. The main focus was the optimisation of the solid-phase microextraction step. The influence of the agitation rate, type of fibre, desorption time, extraction time, extraction temperature, desorption temperature, and solvent addition was examined. The method was developed and validated using a mixture of 17 PAHs, 11 potential chlorination by-products (chlorinated and oxidised PAHs) and 6 deuterated standards. The limit of quantification was 10 ng/L for all target compounds. The validated method was used to analyse drinking water samples from three different drinking water distribution networks and the presumably coal tar-based pipe coatings of two pipe sections. A number of PAHs were detected in all three networks although individual compositions varied. Several PAH chlorination by-products (anthraquinone, fluorenone, cyclopenta[d,e,f]phenanthrenone, 3-chlorofluoranthene, and 1-chloropyrene) were also found, their presence correlating closely with that of their respective parent compounds. Their concentrations were always below 100 ng/L. In the coatings, all PAHs targeted were detected although concentrations varied between the two coatings (76-12,635 mg/kg and 12-6295 mg/kg, respectively). A number of chlorination by-products (anthraquinone, fluorenone, cyclopenta[d,e,f]phenanthrenone, 3-chlorofluoranthene, and 1-chloropyrene) were also detected (from 40 to 985 mg/kg), suggesting that the reaction of PAHs with disinfectant agents takes place in the coatings and not in the water phase after migration. Copyright © 2013 Elsevier B.V. All rights reserved.

Thermal Processing Effects on the Adhesive Strength of PS304 High Temperature Solid Lubricant Coatings

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Edmonds, Brian J.; Benoy, Patricia A.

2001-01-01

In this paper the effects of post deposition heat treatments on the cohesive and adhesive strength properties of PS304, a plasma sprayed nickel-chrome based, high temperature solid lubricant coating deposited on stainless steel, are studied. Plasma spray deposited coating samples were exposed in air at temperatures from 432 to 650 C for up to 500 hr to promote residual stress relief, enhance particle to particle bonding and increase coating to substrate bond strength. Coating pull-off strength was measured using a commercial adhesion tester that utilizes 13 mm diameter aluminum pull studs attached to the coating surface with epoxy. Pull off force was automatically recorded and converted to coating pull off strength. As deposited coating samples were also tested as a baseline. The as-deposited (untreated) samples either delaminated at the coating-substrate interface or failed internally (cohesive failure) at about 17 MPa. Samples heat treated at temperatures above 540 C for 100 hr or at 600 C or above for more than 24 hr exhibited strengths above 31 MPa, nearly a two fold increase. Coating failure occurred inside the body of the coating (cohesive failure) for nearly all of the heat-treated samples and only occasionally at the coating substrate interface (adhesive failure). Metallographic analyses of heat-treated coatings indicate that the Nickel-Chromium binder in the PS304 appears to have segregated into two phases, a high nickel matrix phase and a high chromium precipitated phase. Analysis of the precipitates indicates the presence of silicon, a constituent of a flow enhancing additive in the commercial NiCr powder. The exact nature and structure of the precipitate phase is not known. This microstructural change is believed to be partially responsible for the coating strength increase. Diffusion bonding between particles may also be playing a role. Increasing the heat treatment temperature, exposure time or both accelerate the heat treatment process. Preliminary measurements indicate that the heat treatment also results in a one time, permanent coating thickness increase of about 3%. Based upon these results, the incorporation of a heat treatment prior to final finishing has been incorporated in the application process of this coating technology.

Apparatus and Method for Increasing the Diameter of Metal Alloy Wires Within a Molten Metal Pool

DOEpatents

Hartman, Alan D.; Argetsinger, Edward R.; Hansen, Jeffrey S.; Paige, Jack I.; King, Paul E.; Turner, Paul C.

2002-01-29

In a dip forming process the core material to be coated is introduced directly into a source block of coating material eliminating the need for a bushing entrance component. The process containment vessel or crucible is heated so that only a portion of the coating material becomes molten, leaving a solid portion of material as the entrance port of, and seal around, the core material. The crucible can contain molten and solid metals and is especially useful when coating core material with reactive metals. The source block of coating material has been machined to include a close tolerance hole of a size and shape to closely fit the core material. The core material moves first through the solid portion of the source block of coating material where the close tolerance hole has been machined, then through a solid/molten interface, and finally through the molten phase where the diameter of the core material is increased. The crucible may or may not require water-cooling depending upon the type of material used in crucible construction. The system may operate under vacuum, partial vacuum, atmospheric pressure, or positive pressure depending upon the type of source material being used.

Apparatus and method for increasing the diameter of metal alloy wires within a molten metal pool

DOEpatents

Hartman, Alan D.; Argetsinger, Edward R.; Hansen, Jeffrey S.; Paige, Jack I.; King, Paul E.; Turner, Paul C.

2002-01-29

In a dip forming process the core material to be coated is introduced directly into a source block of coating material eliminating the need for a bushing entrance component. The process containment vessel or crucible is heated so that only a portion of the coating material becomes molten, leaving a solid portion of material as the entrance port of, and seal around, the core material. The crucible can contain molten and solid metals and is especially useful when coating core material with reactive metals. The source block of coating material has been machined to include a close tolerance hole of a size and shape to closely fit the core material. The core material moves first through the solid portion of the source block of coating material where the close tolerance hole has been machined, then through a solid/molten interface, and finally through the molten phase where the diameter of the core material is increased. The crucible may or may not require water-cooling depending upon the type of material used in crucible construction. The system may operate under vacuum, partial vacuum, atmospheric pressure, or positive pressure depending upon the type of source material being used.

Fabrication of polyaniline-coated halloysite nanotubes by in situ chemical polymerization as a solid-phase microextraction coating for the analysis of volatile organic compounds in aqueous solutions.

PubMed

Abolghasemi, Mir Mahdi; Arsalani, Naser; Yousefi, Vahid; Arsalani, Mahmood; Piryaei, Marzieh

2016-03-01

We have synthesized an organic-inorganic polyaniline-halloysite nanotube composite by an in situ polymerization method. This nanocomposite is immobilized on a stainless-steel wire and can be used as a fiber coating for solid-phase microextraction. It was found that our new solid-phase microextraction fiber is an excellent adsorbent for the extraction of some volatile organic compounds in aqueous samples in combination with gas chromatography and mass spectrometry. The coating can be prepared easily, is mechanically stable, and exhibits relatively high thermal stability. It is capable of extracting phenolic compounds from water samples. Following thermal desorption, the phenols were quantified by gas chromatography with mass spectrometry. The effects of extraction temperature, extraction time, sample ionic strength, stirring rate, pH, desorption temperature and desorption time were studied. Under optimal conditions, the repeatability for one fiber (n = 5), expressed as the relative standard deviation, is between 6.2 and 9.1%. The detection limits range from 0.005 to 4 ng/mL. The method offers the advantage of being simple to use, with a shorter analysis time, lower cost of equipment and higher thermal stability of the fiber in comparison to conventional methods of analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The influence of the ion plasma flow on the phase composition and microhardness of carbon coatings doped with metals

NASA Astrophysics Data System (ADS)

Rudenkov, A. S.; Piliptsou, D. G.; Luchnikov, P. A.; Rogachev, A. V.; Jiang, Xiaohong; Fedosenko, N. N.

2018-01-01

The Raman spectroscopy method established that subsequent treatment with ion ions leads to a change in the microstructure of coatings based on carbon and metals. It is established that the structure change is determined by the changes occurring at the interface and depends on the sp3 → sp2 phase transition due to the appearance of local thermal peaks at the end of tracks of nitrogen ions implanted in the coating volume. It is shown that the microhardness of metal-carbon coatings (α-C: Cu, α-C: Ti, α-C:Al) increases after ion-plasma treatment, which is determined by the formation of solid interstitial phases based on CNx and metal carbonitrides.

Investigation of phase-change coatings for variable thermal control of spacecraft

NASA Technical Reports Server (NTRS)

Kelliher, W. C.; Young, P. R.

1972-01-01

An investigation was conducted to determine the feasibility of producing a spacecraft coating system that could vary the ratio of its solar absorptance to thermal emittance to adjust automatically for changes in the thermal balance of a spacecraft. This study resulted in a new concept called the phase-change effect which uses the change that occurs in the optical properties of many materials during the phase transition from a crystalline solid to an amorphous material. A series of two-component model coatings was developed which, when placed on a highly reflecting substrate, exhibited a sharp decrease in solar absorptance within a narrow temperature range. A variable thermal control coating can have a significant amount of temperature regulation with the phase-change effect. Data are presented on several crystallite-polymer formulations, their physical and optical properties, and associated phase-change temperatures. Aspects pertaining to their use in a space environment and an example of the degree of thermal regulation attainable with these coatings is also given.

Preparation of a novel hyperbranched carbosilane-silica hybrid coating for trace amount detection by solid phase microextraction/gas chromatography.

PubMed

Chen, Guowen; Li, Wenjie; Zhang, Chen; Zhou, Chuanjian; Feng, Shengyu

2012-09-21

Phenyl-ended hyperbranched carbosilane (HBC) is synthesized and immobilized onto the inner wall of a fused silica capillary column using a sol-gel process. The hybrid coating layer formed is used as a stationary phase for gas chromatography (GC) and as an adsorption medium for solid phase microextraction (SPME). Trifluoroacetic acid, as a catalyst in this process, helps produce a homogeneous hybrid coating layer. This result is beneficial for better column chromatographic performances, such as high efficiency and high resolution. Extraction tests using the novel hybrid layer show an extraordinarily large adsorption capacity and specific adsorption behavior for aromatic compounds. A 1 ppm trace level detectability is obtained with the SPME/GC work model when both of the stationary phase and adsorption layer bear a hyperbranched structure. A large amount of phenyl groups and a low viscosity of hyperbranched polymers contribute to these valuable properties, which are important to environment and safety control, wherein detection sensitivity and special adsorption behavior are usually required. Copyright © 2012 Elsevier B.V. All rights reserved.

Composite coating for low friction and wear applications and method thereof

DOEpatents

Besmann, T.M.; Blau, P.J.; Lee, W.Y.; Bae, Y.W.

1998-01-20

An article having a multiphase composite lubricant coating of a hard refractory matrix phase of titanium nitride dispersed with particles of a solid lubricating phase of molybdenum disulfide is prepared by heating the article to temperatures between 350 and 850 C in a reaction vessel at a reduced pressure and passing a gaseous mixture of Ti((CH{sub 3}){sub 2}N){sub 4}, MoF{sub 6}, H{sub 2}S and NH{sub 3} over the heated article forming a multiphase composite lubricant coating on the article. 1 fig.

Composite coating for low friction and wear applications and method thereof

DOEpatents

Besmann, Theodore M.; Blau, Peter J.; Lee, Woo Y.; Bae, Yong W.

1998-01-01

An article having a multiphase composite lubricant coating of a hard refractory matrix phase of titanium nitride dispersed with particles of a solid lubricating phase of molybdenum disulfide is prepared by heating the article to temperatures between 350.degree. and 850.degree. C. in a reaction vessel at a reduced pressure and passing a gaseous mixture of Ti((CH.sub.3).sub.2 N).sub.4, MoF.sub.6, H.sub.2 S and NH.sub.3 over the heated article forming a multiphase composite lubricant coating on the article.

Development of a special purpose spacecraft coating, phase 4

NASA Technical Reports Server (NTRS)

Gillman, H. D.

1980-01-01

Coating formulations based on a fluorocarbon resin were evaluated for use on spacecraft exteriors. Formulations modified with an acrylic resin were found to have excellent offgassing properties. A much less expensive process for increasing to solid content of the fluorocarbon latex was developed.

Sol-gel titania-coated needles for solid phase dynamic extraction-GC/MS analysis of desomorphine and desocodeine.

PubMed

Su, Chi-Ju; Srimurugan, Sankarewaran; Chen, Chinpiao; Shu, Hun-Chi

2011-01-01

Novel sol-gel titania film coated needles for solid-phase dynamic extraction (SPDE)-GC/MS analysis of desomorphine and desocodeine are described. The high thermal stability of titania film permits efficient extraction and analysis of poorly volatile opiate drugs. The influences of sol-gel reaction time, coating layer, extraction and desorption time and temperature on the SPDE needle performance were investigated. The deuterium labeled internal standard was introduced either during the extraction of analyte or directly injected to GC after the extraction process. The latter method was shown to be more sensitive for the analysis of water and urine samples containing opiate drugs. The proposed conditions provided a wide linear range (from 5-5000 ppb), and satisfactory linearity, with R(2) values from 0.9958 to 0.9999, and prominent sensitivity, LOQs (1.0-5.0 ng/g). The sol-gel titania film coated needle with SPDE-GC/MS will be a promising technique for desomorphine and desocodeine analysis in urine.

New NbCd2 Phase in Niobium-Cadmium Coating Films

NASA Astrophysics Data System (ADS)

Volodin, V. N.; Tuleushev, Yu. Zh.; Zhakanbaev, E. A.; Tsai, K. V.; Rofman, O. V.

2018-02-01

Solid solutions in the form of alloy coatings have been obtained for the first time in the Cd concentration range of 64.5% using ion-plasma sputtering and the codeposition of Nb and Cd ultrafine particles. This supports thermal fluctuation melting and the coalescence of fine particles. A coating of niobium and cadmium layers less than 2 nm thick at 68 at % Cd results in the formation of a new phase identified as NbCd2. The tetragonal fcc phase with lattice parameters a = 0.84357 nm and c = 0.54514 nm forms directly during film coating. XRD data for the identification of the intermetallic compound have been determined. The thermal stability of the NbCd 2 intermetallic compound is limited by 200°C. The properties of the synthesized NbCd 2 phase are typical of semiconductors.

Microstructure and wear resistance of laser cladded Ni-Cr-Co-Ti-V high-entropy alloy coating after laser remelting processing

NASA Astrophysics Data System (ADS)

Cai, Zhaobing; Cui, Xiufang; Liu, Zhe; Li, Yang; Dong, Meiling; Jin, Guo

2018-02-01

An attempt, combined with the technologies of laser cladding and laser remelting, has been made to develop a Ni-Cr-Co-Ti-V high entropy alloy coating. The phase composition, microstructure, micro-hardness and wear resistance (rolling friction) were studied in detail. The results show that after laser remelting, the phase composition remains unchanged, that is, as-cladded coating and as-remelted coatings are all composed of (Ni, Co)Ti2 intermetallic compound, Ti-rich phase and BCC solid solution phase. However, after laser remelting, the volume fraction of Ti-rich phase increases significantly. Moreover, the micro-hardness is increased, up to ∼900 HV at the laser remelting parameters: laser power of 1 kW, laser spot diameter of 3 mm, and laser speed of 10 mm/s. Compared to the as-cladded high-entropy alloy coating, the as-remelted high-entropy alloy coatings have high friction coefficient and low wear mass loss, indicating that the wear resistance of as-remelted coatings is improved and suggesting practical applications, like coatings on brake pads for wear protection. The worn surface morphologies show that the worn mechanism of as-cladded and as-remelted high-entropy alloy coatings are adhesive wear.

Integrated atomic layer deposition and chemical vapor reaction for the preparation of metal organic framework coatings for solid-phase microextraction Arrow.

PubMed

Lan, Hangzhen; Salmi, Leo D; Rönkkö, Tuukka; Parshintsev, Jevgeni; Jussila, Matti; Hartonen, Kari; Kemell, Marianna; Riekkola, Marja-Liisa

2018-09-18

New chemical vapor reaction (CVR) and atomic layer deposition (ALD)-conversion methods were utilized for preparation of metal organic frameworks (MOFs) coatings of solid phase microextraction (SPME) Arrow for the first time. With simple, easy and convenient one-step reaction or conversion, four MOF coatings were made by suspend ALD iron oxide (Fe 2 O 3 ) film or aluminum oxide (Al 2 O 3 ) film above terephthalic acid (H 2 BDC) or trimesic acid (H 3 BTC) vapor. UIO-66 coating was made by zirconium (Zr)-BDC film in acetic acid vapor. As the first documented instance of all-gas phase synthesis of SPME Arrow coatings, preparation parameters including CVR/conversion time and temperature, acetic acid volume, and metal oxide film/metal-ligand films thickness were investigated. The optimal coatings exhibited crystalline structures, excellent uniformity, satisfactory thickness (2-7.5 μm), and high robustness (>80 times usage). To study the practical usefulness of the coatings for the extraction, several analytes with different chemical properties were tested. The Fe-BDC coating was found to be the most selective and sensitive for the determination of benzene ring contained compounds due to its highly hydrophobic surface and unsaturated metal site. UIO-66 coating was best for small polar, aromatic, and long chain polar compounds owing to its high porosity. The usefulness of new coatings were evaluated for gas chromatography-mass spectrometer (GC-MS) determination of several analytes, present in wastewater samples at three levels of concentration, and satisfactory results were achieved. Copyright © 2018 Elsevier B.V. All rights reserved.

Replacement of Ablators with Phase-Change Material for Thermal Protection of STS Elements

NASA Technical Reports Server (NTRS)

Kaul, Raj K.; Stuckey, Irvin; Munafo, Paul M. (Technical Monitor)

2002-01-01

As part of the research and development program to develop new Thermal Protection System (TPS) materials for aerospace applications at NASA's Marshall Space Flight Center (MSFC), an experimental study was conducted on a new concept for a non-ablative TPS material. Potential loss of TPS material and ablation by-products from the External Tank (ET) or Solid Rocket Booster (SRB) during Shuttle flight with the related Orbiter tile damage necessitates development of a non-ablative thermal protection system. The new Thermal Management Coating (TMC) consists of phase-change material encapsulated in micro spheres and a two-part resin system to adhere the coating to the structure material. The TMC uses a phase-change material to dissipate the heat produced during supersonic flight rather than an ablative material. This new material absorbs energy as it goes through a phase change during the heating portion of the flight profile and then the energy is slowly released as the phase-change material cools and returns to its solid state inside the micro spheres. The coating was subjected to different test conditions simulating design flight environments at the NASA/MSFC Improved Hot Gas Facility (IHGF) to study its performance.

Development of novel molecularly imprinted solid-phase microextraction fiber and its application for the determination of triazines in complicated samples coupled with high-performance liquid chromatography.

PubMed

Hu, Xiaogang; Hu, Yuling; Li, Gongke

2007-04-13

A novel molecularly imprinted polymer (MIP) coated solid-phase microextraction (SPME) fiber that could be coupled directly to high-performance liquid chromatography (HPLC) was prepared with prometryn as the template molecule. The characteristics and application of this fiber were investigated. Electron microscope photographs indicated that the MIP coating with average thickness of 25.0 microm was homogeneous and porous. The extraction yield of prometryn with the MIP-coated fibers was 10 times as much as that with the non-imprinted polymer (NIP) coated fibers. And special selectivity to other triazines which have similar structure to prometryn was discovered with the MIP-coated fibers. A method for the determination of triazines by the MIP-coated SPME coupled with HPLC was developed. The optimized extraction conditions were studied. Detection limits for the triazines studied were within the range of 0.012-0.090 microg/L. The method was applied to five triazines determination in the spiked soybean, corn, lettuce, and soil samples with the recoveries of 78.0-103.5%, 82.4-113.4%, 75.5-83.4%, and 81.0-106.1%, respectively. The MIP-coated fibers are suitable for the selective extraction of trace triazines in complicated samples.

A solid-phase glycosyltransferase assay for high-throughput screening in drug discovery research.

PubMed

Donovan, R S; Datti, A; Baek, M G; Wu, Q; Sas, I J; Korczak, B; Berger, E G; Roy, R; Dennis, J W

1999-10-01

Glycosyltransferases mediate changes in glycosylation patterns which, in turn, may affect the function of glycoproteins and/or glycolipids and, further downstream, processes of development, differentiation, transformation and cell-cell recognition. Such enzymes, therefore, represent valid targets for drug discovery. We have developed a solid-phase glycosyltransferase assay for use in a robotic high-throughput format. Carbohydrate acceptors coupled covalently to polyacrylamide are coated onto 96-well plastic plates. The glycosyltransferase reaction is performed with recombinant enzymes and radiolabeled sugar-nucleotide donor at 37 degrees C, followed by washing, addition of scintillation counting fluid, and measurement of radioactivity using a 96-well beta-counter. Glycopolymer construction and coating of the plastic plates, enzyme and substrate concentrations, and linearity with time were optimized using recombinant Core 2 beta1-6-N-acetylglucosaminyltransferase (Core 2 GlcNAc-T). This enzyme catalyzes a rate-limiting reaction for expression of polylactosamine and the selectin ligand sialyl-Lewis(x) in O-glycans. A glycopolymer acceptor for beta1-6-N-acetylglucosaminyltransferase V was also designed and shown to be effective in the solid-phase assay. In a high-throughput screen of a microbial extract library, the coefficient of variance for positive controls was 9.4%, and high concordance for hit validation was observed between the Core 2 GlcNAc-T solid-phase assay and a standard solution-phase assay. The solid-phase assay format, which can be adapted for a variety of glycosyltransferase enzymes, allowed a 5-6 fold increase in throughput compared to the corresponding solution-phase assay.

Preparation of surfactant-free nanoparticles of methacrylic acid copolymers used for film coating.

PubMed

Nguyen, Cung An; Konan-Kouakou, Yvette Niamien; Allémann, Eric; Doelker, Eric; Quintanar-Guerrero, David; Fessi, Hatem; Gurny, Robert

2006-07-28

The aim of the present study was to prepare surfactant-free pseudolatexes of various methacrylic acid copolymers. These aqueous colloidal dispersions of polymeric materials for oral administration are intended for film coating of solid dosage forms or for direct manufacturing of nanoparticles. Nanoparticulate dispersions were produced by an emulsification-diffusion method involving the use of partially water-miscible solvents and the mutual saturation of the aqueous and organic phases prior to the emulsification in order to reduce the initial thermodynamic instability of the emulsion. Because of the self-emulsifying properties of the methacrylic acid copolymers, it was possible to prepare aqueous dispersions of colloidal size containing up to 30% wt/vol of Eudragit RL, RS, and E using 2-butanone or methyl acetate as partially water-miscible solvents, but without any surfactant. However, in the case of the cationic Eudragit E, protonation of the tertiary amine groups by acidification of the aqueous phase was necessary to improve the emulsion stability in the absence of surfactant and subsequently to prevent droplet coalescence during evaporation. In addition, a pseudolatex of Eudragit E was used to validate the coating properties of the formulation for solid dosage forms. Film-coated tablets of quinidine sulfate showed a transparent glossy continuous film that was firmly attached to the tablet. The dissolution profile of quinidine sulfate from the tablets coated with the Eudragit E pseudolatex was comparable to that of tablets coated with an acetonic solution of Eudragit E. Furthermore, both types of coating ensured similar taste masking. The emulsification-evaporation method used was shown to be appropriate for the preparation of surfactant-free colloidal dispersions of the 3 types of preformed methacrylic acid copolymers; the dispersions can subsequently be used for film coating of solid dosage forms.

Graphene oxide decorated with silver nanoparticles as a coating on a stainless-steel fiber for solid-phase microextraction.

PubMed

Wang, Licheng; Hou, Xiudan; Li, Jubai; Liu, Shujuan; Guo, Yong

2015-07-01

A novel graphene oxide decorated with silver nanoparticles coating on a stainless-steel fiber for solid-phase microextraction was prepared. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to characterize the coating surface and showed that silver nanoparticles were dispersed on the wrinkled graphene oxide surface. Coupled to gas chromatography with flame ionization detection, the extraction abilities of the fiber for polycyclic aromatic hydrocarbons were examined in the headspace solid-phase microextraction mode. The extraction parameters including adsorption time, adsorption temperature, salt concentration, desorption time and desorption temperature were investigated. Under the optimized condition, wide linearity with low limits of detection from 2 to 10 ng/L was obtained. The relative standard deviations for single-fiber repeatability and fiber-to-fiber reproducibility were less than 10.6 and 17.5%, respectively. The enrichment factors were from 1712.5 to 4503.7, showing the fiber has good extraction abilities. Moreover, the fiber exhibited a good stability and could be reused for more than 120 times. The established method was also applied for determination of polycyclic aromatic hydrocarbons in two real water samples and the recoveries of analytes ranged from 84.4-116.3% with relative standard deviations less than 16.2%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metallurgical features of the formation of a solid-phase metal joint upon electric-circuit heating

NASA Astrophysics Data System (ADS)

Latypov, R. A.; Bulychev, V. V.; Zybin, I. N.

2017-06-01

The thermodynamic conditions of formation of a joint between metals using the solid-phase methods of powder metallurgy, welding, and deposition of functional coatings upon electric-current heating of the surfaces to be joined are studied. Relations are obtained to quantitatively estimate the critical sizes of the circular and linear active centers that result in the formation of stable bonding zones.

Self-healing atmospheric plasma sprayed Mn1.0Co1.9Fe0.1O4 protective interconnector coatings for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Grünwald, Nikolas; Sebold, Doris; Sohn, Yoo Jung; Menzler, Norbert Heribert; Vaßen, Robert

2017-09-01

Dense coatings on metallic interconnectors are necessary to suppress chromium poisoning of SOFC cathodes. Atmospherically plasma sprayed (APS) Mn1.0Co1.9Fe0.1O4 (MCF) protective layers demonstrated reduced chromium related degradation in laboratory and stack tests. Previous analyses revealed strong microstructural changes comparing the coating's as-sprayed and operated condition. This work concentrates on the layer-densification and crack-healing observed by annealing APS-MCF in air, which simulates the cathode operation conditions. The effect is described by a volume expansion induced by a phase transformation. Reducing conditions during the spray process lead to a deposition of the MCF in a metastable rock salt configuration. Annealing in air activates diffusion processes for a phase transformation to the low temperature stable spinel phase (T < 1050 °C). This transformation is connected to an oxygen incorporation which occurs at regions facing high oxygen partial pressures, as there are the sample surface, cracks and pore surfaces. Calculations reveal a volume expansion induced by the oxygen uptake which seals the cracks and densifies the coating. The process decelerates when the cracks are closed, as the gas route is blocked and further oxidation continues over solid state diffusion. The self-healing abilities of metastable APS coatings could be interesting for other applications.

Planar solid-phase microextraction-ion mobility spectrometry: a diethoxydiphenylsilane-based coating for the detection of explosives and explosive taggants.

PubMed

Mattarozzi, M; Bianchi, F; Bisceglie, F; Careri, M; Mangia, A; Mori, G; Gregori, A

2011-03-01

A novel diethoxydiphenylsilane-based coating for planar solid-phase microextraction was developed using sol-gel technology and used for ion mobility spectrometric detection of the explosives 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and of the explosive taggant ethylene glycol dinitrate. The trap was characterized in terms of coating thickness, morphology, inter-batch repeatability, and extraction efficiency. An average thickness of 143 ± 13 μm with a uniform distribution of the coating was obtained. Good performances of the developed procedure in terms of both intra-batch and inter-batch repeatability with relative standard deviations <7% were obtained. Experimental design and desirability function were used to find the optimal conditions for simultaneous headspace extraction of the investigated compounds: the optimal values were found in correspondence of a time and a temperature of extraction of 45 min and 40 °C, respectively. Detection and quantitation limits in low nanogram levels were achieved proving the superior extraction capability of the developed coating, obtaining ion mobility spectrometric responses at least two times higher than those achieved using commercial teflon and paper traps.

Development and characterization of laser surface cladding (Ti,W)C reinforced Ni-30Cu alloy composite coating on copper

NASA Astrophysics Data System (ADS)

Yan, Hua; Zhang, Peilei; Yu, Zhishui; Li, Chonggui; Li, Ruidi

2012-07-01

To improve the wear resistance of copper components, laser surface cladding (LSC) was applied to deposit (Ti,W)C reinforced Ni-30Cu alloy composite coating on copper using a cladding interlayer of Ni-30Cu alloy by Nd:YAG laser. The microstructure and phases of the composite coating were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray energy dispersive microanalysis (EDX). Microhardness tester and pin-on-disc wear tester were employed to evaluate the hardness and dry-sliding wear resistance. The results show that crack-free composite coating with metallurgical bonding to the copper substrate is obtained. Phases identified in the (Ti,W)C-reinforced Ni-30Cu alloy composite layer are composed of TiWC2 reinforcements and (Ni,Cu) solid solution. TiWC2 reinforcements are distributed uniformly in the (Ni,Cu) solid solution matrix with dendritic morphology in the upper region and with particles in the mid-lower region. The microhardness and wear properties of the composite coating are improved significantly in comparison to the as-received copper substrate due to the addition of 50 wt% (Ti,W)C multicarbides.

Ionic liquid polymer functionalized carbon nanotubes-doped poly(3,4-ethylenedioxythiophene) for highly-efficient solid-phase microextraction of carbamate pesticides.

PubMed

Wu, Mian; Wang, Liying; Zeng, Baizhao; Zhao, Faqiong

2016-04-29

A poly(3,4-ethylenedioxythiophene)-ionic liquid polymer functionalized multiwalled carbon nanotubes (PEDOT-PIL/MWCNTs) composite solid-phase microextraction (SPME) coating was fabricated by electrodeposition. After being dipped in Nafion solution, a Nafion-modified coating was obtained. The outer layer Nafion played a crucial role in enhancing the durability and stability of the coating, thus it was robust enough for replicated extraction for at least 150 times without decrease of extraction performance. The Nafion-modified coating exhibited much higher sensitivity than commercial coatings for the direct extraction of carbamate pesticides in aqueous solutions, due to its strong hydrophobic effect and π-π affinity based enrichment. When it was used for the determination of carbamate pesticides in combination with gas chromatography-flame ionization detection, good linearity (correlation coefficients higher than 0.9981), low limits of detection (15.2-27.2 ng/L) and satisfactory precision (relative standard deviation <8.2%, n=5) were achieved. The developed method was applied to the analysis of four carbamate pesticides in apple and lettuce samples, and acceptable recoveries (i.e. 87.5-106.5%) were obtained for the standard addition. Copyright © 2016 Elsevier B.V. All rights reserved.

Microstructural, phase evolution and corrosion properties of silicon carbide reinforced pulse electrodeposited nickel-tungsten composite coatings

NASA Astrophysics Data System (ADS)

Singh, Swarnima; Sribalaji, M.; Wasekar, Nitin P.; Joshi, Srikant; Sundararajan, G.; Singh, Raghuvir; Keshri, Anup Kumar

2016-02-01

Silicon carbide (SiC) reinforced nickel-tungsten (Ni-W) coatings were successfully fabricated on steel substrate by pulse electrodeposition method (PED) and the amount of SiC was varied as 0 g/l, 2 g/l, and 5 g/l in Ni-W coating. Effect of subsequent addition of SiC on microstructures, phases and on corrosion property of the coating was investigated. Field emission scanning electron microscopy (FE-SEM) image of the surface morphology of the coating showed the transformation from the dome like structure to turtle shell like structure. X-ray diffraction (XRD) of Ni-W-5 g/l SiC showed the disappearance of (220) plane of Ni(W), peak splitting in major peak of Ni(W) and formation of distinct peak of W(Ni) solid solution. Absence of (220) plane, peak splitting and presence of W(Ni) solid solution was explained by the high resolution transmission electron microscopy (HR-TEM) images. Tafel polarization plot was used to study the corrosion property of the coatings in 0.5 M NaCl solution. Ni-W-5 g/l SiC coating was showed higher corrosion resistance (i.e. ∼21% increase in corrosion potential, Ecorr) compared to Ni-W coating. Two simultaneous phenomena have been identified for the enhanced corrosion resistance of Ni-W-5 g/l SiC coating. (a) Presence of crystallographic texture (b) formation of continuous double barrier layer of NiWO4 and SiO2.

Development of a polymeric ionic liquid coating for direct-immersion solid-phase microextraction using polyhedral oligomeric silsesquioxane as cross-linker.

PubMed

Chen, Chunyan; Liang, Xiaotong; Wang, Jianping; Zou, Ying; Hu, Huiping; Cai, Qingyun; Yao, Shouzhuo

2014-06-27

A novel solid-phase microextraction (SPME) fiber was developed by chemical binding of a crosslinked polymeric ionic liquid (PIL) on the surface of an anodized Ti wire, and was applied in direct-immersion mode for the extraction of perfluorinated compounds (PFCs) from water samples coupled with high performance liquid chromatography-tandem mass spectrometry analysis. The PIL coatings were synthesized by using 1-vinyl-3-hexylimidazolium hexafluorophosphate as monomer and methylacryloyl-substituted polyhedral oligomeric silsesquioxane (POSS) as cross-linker via free radical reaction. The proposed fiber coating exhibited high mechanical stability due to the chemical bonding between the coating and the Ti wire surface. The integration of POSS reagent enhanced the organic solvent resistance of the coating. The parameters affecting the extraction performance of the fiber coating including extraction time, pH of solution, ionic strength and desorption conditions were optimized. The developed PIL-POSS fiber showed good linearity (R<0.998) between 0.1 and 50ngmL(-1) with method detection limits ranging from 0.005 to 0.08ngmL(-1) depending on the analyte, and with relative standard deviation for single-fiber repeatability and fiber-to-fiber reproducibility less than 8.6% and 9.5%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Are metal-organic frameworks able to provide a new generation of solid-phase microextraction coatings? - A review.

PubMed

Rocío-Bautista, Priscilla; Pacheco-Fernández, Idaira; Pasán, Jorge; Pino, Verónica

2016-10-05

Solid-phase microextraction (SPME) is a powerful technique commonly used in sample preparation for extraction/preconcentration of analytes from a wide variety of samples. Among the trends in improving SPME applications, current investigations are focused on the development of novel coatings able to improve the extraction efficiency, sensitivity, and thermal and mechanical stability, within other properties, of current commercial SPME fibers. Metal-organic frameworks (MOFs) merit to be highlighted as promising sorbent materials in SPME schemes. MOFs are porous hybrid materials composed by metal ions and organic linkers, presenting the highest surface areas known, with ease synthesis and high tuneability, together with adequate chemical and thermal stability. For MOF based-SPME fibers, it results important to pretreat adequately the SPME supports to ensure the correct formation of the MOF onto the fiber or the attachment MOF-support. This, in turn, will increase the final stability of the fiber while generating uniform coatings. This review provides a critical overview of the current state of the use of MOFs as SPME coatings, not only highlighting the advantages of these materials versus commercial SPME coatings in terms of stability, selectivity, and sensitivity; but also insightfully describing the current methods to obtain reproducible MOF-based SPME coatings. Copyright © 2016 Elsevier B.V. All rights reserved.

Heterogeneous ice nucleation on phase-separated organic-sulfate particles: effect of liquid vs. glassy coatings

NASA Astrophysics Data System (ADS)

Schill, G. P.; Tolbert, M. A.

2013-05-01

Atmospheric ice nucleation on aerosol particles relevant to cirrus clouds remains one of the least understood processes in the atmosphere. Upper tropospheric aerosols as well as sub-visible cirrus residues are known to be enhanced in both sulfates and organics. The hygroscopic phase transitions of organic-sulfate particles can have an impact on both the cirrus cloud formation mechanism and resulting cloud microphysical properties. In addition to deliquescence and efflorescence, organic-sulfate particles are known to undergo another phase transition known as liquid-liquid phase separation. The ice nucleation properties of particles that have undergone liquid-liquid phase separation are unknown. Here, Raman microscopy coupled with an environmental cell was used to study the low temperature deliquescence, efflorescence, and liquid-liquid phase separation behavior of 2 : 1 mixtures of organic polyols (1,2,6-hexanetriol and 1 : 1 1,2,6-hexanetriol + 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol) and ammonium sulfate from 240-265 K. Further, the ice nucleation efficiency of these organic-sulfate systems after liquid-liquid phase separation and efflorescence was investigated from 210-235 K. Raman mapping and volume-geometry analysis indicate that these particles contain solid ammonium sulfate cores fully engulfed in organic shells. For the ice nucleation experiments, we find that if the organic coatings are liquid, water vapor diffuses through the shell and ice nucleates on the ammonium sulfate core. In this case, the coatings minimally affect the ice nucleation efficiency of ammonium sulfate. In contrast, if the coatings become semi-solid or glassy, ice instead nucleates on the organic shell. Consistent with recent findings that glasses can be efficient ice nuclei, the phase-separated particles are nearly as efficient at ice nucleation as pure crystalline ammonium sulfate.

Heterogeneous ice nucleation on phase-separated organic-sulfate particles: effect of liquid vs. glassy coatings

NASA Astrophysics Data System (ADS)

Schill, G. P.; Tolbert, M. A.

2012-12-01

Atmospheric ice nucleation on aerosol particles relevant to cirrus clouds remains one of the least understood processes in the atmosphere. Upper tropospheric aerosols as well as sub-visible cirrus residues are known to be enhanced in both sulfates and organics. The hygroscopic phase transitions of organic-sulfate particles can have an impact on both the cirrus cloud formation mechanism and resulting cloud microphysical properties. In addition to deliquescence and efflorescence, organic-sulfate particles are known to undergo another phase transition known as liquid-liquid phase separation. The ice nucleation properties of particles that have undergone liquid-liquid phase separation are unknown. Here, Raman microscopy coupled with an environmental cell was used to study the low temperature deliquescence, efflorescence, and liquid-liquid phase separation behavior of 2:1 mixtures of organic polyols (1,2,6-hexanetriol, and 1:1 1,2,6-hexanetriol +2,2,6,6-tetrakis(hydroxymethyl)cycohexanol) and ammonium sulfate from 240-265 K. Further, the ice nucleation efficiency of these organic-sulfate systems after liquid-liquid phase separation and efflorescence was investigated from 210-235 K. Raman mapping and volume-geometry analysis indicates that these particles contain solid ammonium sulfate cores fully engulfed in organic shells. For the ice nucleation experiments, we find that if the organic coatings are liquid, water vapor diffuses through the shell and ice nucleates on the ammonium sulfate core. In this case, the coatings minimally affect the ice nucleation efficiency of ammonium sulfate. In contrast, if the coatings become semi-solid or glassy, ice instead nucleates on the organic shell. Consistent with recent findings that glasses can be efficient ice nuclei, the phase separated particles are nearly as efficient at ice nucleation as pure crystalline ammonium sulfate.

Wetting in a Colloidal Liquid-Gas System

NASA Astrophysics Data System (ADS)

Wijting, W. K.; Besseling, N. A.; Stuart, M. A.

2003-05-01

We present first observations of wetting phenomena in depletion interaction driven, phase separated colloidal dispersions (coated silica cyclohexane-polydimethylsiloxane). The contact angle of the colloidal liquid-gas interface at a solid substrate (coated glass) was determined for a series of compositions. Upon approach to the critical point, a transition occurs from partial to complete wetting.

Wetting in a colloidal liquid-gas system.

PubMed

Wijting, W K; Besseling, N A M; Stuart, M A Cohen

2003-05-16

We present first observations of wetting phenomena in depletion interaction driven, phase separated colloidal dispersions (coated silica-cyclohexane-polydimethylsiloxane). The contact angle of the colloidal liquid-gas interface at a solid substrate (coated glass) was determined for a series of compositions. Upon approach to the critical point, a transition occurs from partial to complete wetting.

Electrodeposited polyaniline as a fiber coating for solid-phase microextraction of organochlorine pesticides from water.

PubMed

Li, Xiang; Zhong, Ming; Chen, Jianmin

2008-08-01

The study on the performance of polyaniline as a fiber coating for solid-phase microextraction (SPME) purposes has been reported. Polyaniline coatings were directly electrodeposited on the surface of a stainless steel wire and applied for the extraction of some organochlorine pesticides (OCPs) from water samples. Analyses were performed using GC-electron capture detection (GC-ECD). The results obtained show that polyaniline fiber coating is suitable for the successful extraction of organochlorine compounds. This behavior is most probably due to the porous surface structure of polyaniline film, which provides large surface areas and allowed for high extraction efficiency. Experimental parameters such as adsorption and desorption conditions were studied and optimized. The optimized method has an acceptable linearity, with a concentration range of 1-5000 ng/L. Single fiber repeatability and fiber-to-fiber reproducibility were less than 12 and 17%, respectively. High environmental resistance and lower cost are among the advantages of polyaniline fibers over commercially available SPME fibers. The developed method was applied to the analysis of real water samples from Yangtse River and Tianmu Lake.

Drop Printing of Pharmaceuticals: Effect of Molecular Weight on PEG Coated-Naproxen/PEG3350 Solid Dispersions

PubMed Central

Hsu, Hsin-Yun; Toth, Scott; Simpson, Garth J.; Harris, Michael T.

2016-01-01

Solid dispersions have been used to enhance the bioavailability of poorly water-soluble active pharmaceutical ingredients (APIs). However, the solid state phase, compositional uniformity, and scale-up problems are issues that need to be addressed. To allow for highly controllable products, the Drop Printing (DP) technique can provide precise dosages and predictable compositional uniformity of APIs in two/three dimensional structures. In this study, DP was used to prepare naproxen (NAP)/polyethylene glycol 3350 (PEG3350) solid dispersions with PEG coatings of different molecular weights (MW). A comparison of moisture-accelerated crystallization inhibition by different PEG coatings was assessed. Scanning electron microscopy (SEM), second harmonic generation (SHG) microscopy, and differential scanning calorimetry (DSC) analysis were performed to characterize the morphology and quantify the apparent crystallinity of NAP within the solid dispersions. Thermogravimetric analysis (TGA) was employed to measure the water content within each sample. The results suggest that the moisture-accelerated crystallization inhibition capability of the PEG coatings increased with increasing MW of the PEG coating. Besides, to demonstrate the flexibility of DP technology on manufacturing formulation, multilayer tablets with different PEG serving as barrier layers were also constructed, and their dissolution behavior was examined. By applying DP and appropriate materials, it is possible to design various carrier devices used to control the release dynamics of the API. PMID:27041744

Drop Printing of Pharmaceuticals: Effect of Molecular Weight on PEG Coated-Naproxen/PEG3350 Solid Dispersions.

PubMed

Hsu, Hsin-Yun; Toth, Scott; Simpson, Garth J; Harris, Michael T

2015-12-01

Solid dispersions have been used to enhance the bioavailability of poorly water-soluble active pharmaceutical ingredients (APIs). However, the solid state phase, compositional uniformity, and scale-up problems are issues that need to be addressed. To allow for highly controllable products, the Drop Printing (DP) technique can provide precise dosages and predictable compositional uniformity of APIs in two/three dimensional structures. In this study, DP was used to prepare naproxen (NAP)/polyethylene glycol 3350 (PEG3350) solid dispersions with PEG coatings of different molecular weights (MW). A comparison of moisture-accelerated crystallization inhibition by different PEG coatings was assessed. Scanning electron microscopy (SEM), second harmonic generation (SHG) microscopy, and differential scanning calorimetry (DSC) analysis were performed to characterize the morphology and quantify the apparent crystallinity of NAP within the solid dispersions. Thermogravimetric analysis (TGA) was employed to measure the water content within each sample. The results suggest that the moisture-accelerated crystallization inhibition capability of the PEG coatings increased with increasing MW of the PEG coating. Besides, to demonstrate the flexibility of DP technology on manufacturing formulation, multilayer tablets with different PEG serving as barrier layers were also constructed, and their dissolution behavior was examined. By applying DP and appropriate materials, it is possible to design various carrier devices used to control the release dynamics of the API.

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

Cai, Zhaobing

Ni-Cr-Co-Ti-V-Al high-entropy alloy coating on Ti-6Al-4V was synthesized by laser surface alloying. The coating is composed of a B2 matrix and (Co, Ni)Ti{sub 2} compounds with few β-Ti phases. Focused ion beam technique was utilized to prepare TEM sample and TEM observations agree well with XRD and SEM results. The formation of HEA phases is due to high temperature and rapid cooling rate during laser surface alloying. The thermodynamic parameters, ΔH{sub mix}, ΔS{sub mix}and δ as well as Δχ, should be used to predict the formation of the BCC solid solution, but they are not the strict criteria. Especially whenmore » Δχ reaches a high value (≥ 10%), BCC HEA will be partially decomposed, leading to the formation of (Co, Ni)Ti{sub 2} compound phases. - Highlights: •Preparing HEA coating on Ti-6Al-4V by laser surface alloying is successful. •The synthesized HEA coating mainly consists of BCC HEA and (Co, Ni)Ti{sub 2} compounds. •FIB technology was used to prepare the sample for TEM analysis. • ΔH{sub mix}, ΔS{sub mix}and δ as well as Δχ, should be all used to predict the formation of solid solution.« less

Thermodynamics and kinetics of pack aluminide coating formation on IN-100

NASA Technical Reports Server (NTRS)

Levine, S. R.; Caves, R. M.

1973-01-01

An investigation of the effects of pack variables on the formation of aluminide coatings on nickel-base superalloy IN-100 was conducted. Also, the thermodynamics and kinetics of coating formation were analyzed. Observed coating weights were in good agreement with predictions made from the analysis. Pack temperature rather than pack aluminum activity controls the principal coating phase formed. In 1 weight percent aluminum packs, aluminum weight gains were related to the halide pack activator. Solid-state nickel diffusion controlled coating formation from sodium fluoride and chloride and ammonium fluoride activated packs. In other ammonium and sodium halide activated 1 weight percent aluminum packs, gaseous diffusion controlled coating formation.

Process for forming a homogeneous oxide solid phase of catalytically active material

DOEpatents

Perry, Dale L.; Russo, Richard E.; Mao, Xianglei

1995-01-01

A process is disclosed for forming a homogeneous oxide solid phase reaction product of catalytically active material comprising one or more alkali metals, one or more alkaline earth metals, and one or more Group VIII transition metals. The process comprises reacting together one or more alkali metal oxides and/or salts, one or more alkaline earth metal oxides and/or salts, one or more Group VIII transition metal oxides and/or salts, capable of forming a catalytically active reaction product, in the optional presence of an additional source of oxygen, using a laser beam to ablate from a target such metal compound reactants in the form of a vapor in a deposition chamber, resulting in the deposition, on a heated substrate in the chamber, of the desired oxide phase reaction product. The resulting product may be formed in variable, but reproducible, stoichiometric ratios. The homogeneous oxide solid phase product is useful as a catalyst, and can be produced in many physical forms, including thin films, particulate forms, coatings on catalyst support structures, and coatings on structures used in reaction apparatus in which the reaction product of the invention will serve as a catalyst.

Metal organic chemical vapor deposition of environmental barrier coatings for the inhibition of solid deposit formation from heated jet fuel

NASA Astrophysics Data System (ADS)

Mohan, Arun Ram

Solid deposit formation from jet fuel compromises the fuel handling system of an aviation turbine engine and increases the maintenance downtime of an aircraft. The deposit formation process depends upon the composition of the fuel, the nature of metal surfaces that come in contact with the heated fuel and the operating conditions of the engine. The objective of the study is to investigate the effect of substrate surfaces on the amount and nature of solid deposits in the intermediate regime where both autoxidation and pyrolysis play an important role in deposit formation. A particular focus has been directed to examining the effectiveness of barrier coatings produced by metal organic chemical vapor deposition (MOCVD) on metal surfaces for inhibiting the solid deposit formation from jet fuel degradation. In the first part of the experimental study, a commercial Jet-A sample was stressed in a flow reactor on seven different metal surfaces: AISI316, AISI 321, AISI 304, AISI 347, Inconel 600, Inconel 718, Inconel 750X and FecrAlloy. Examination of deposits by thermal and microscopic analysis shows that the solid deposit formation is influenced by the interaction of organosulfur compounds and autoxidation products with the metal surfaces. The nature of metal sulfides was predicted by Fe-Ni-S ternary phase diagram. Thermal stressing on uncoated surfaces produced coke deposits with varying degree of structural order. They are hydrogen-rich and structurally disordered deposits, spherulitic deposits, small carbon particles with relatively ordered structures and large platelets of ordered carbon structures formed by metal catalysis. In the second part of the study, environmental barrier coatings were deposited on tube surfaces to inhibit solid deposit formation from the heated fuel. A new CVD system was configured by the proper choice of components for mass flow, pressure and temperature control in the reactor. A bubbler was designed to deliver the precursor into the reactor for the deposition of metal and metal oxide functional coatings by MOCVD. Alumina was chosen as a candidate for metal oxide coating because of its thermal and phase stability. Platinum was chosen as a candidate to utilize the oxygen spillover process to maintain a self-cleaning surface by oxidizing the deposits formed during thermal stressing. Two metal organic precursors, aluminum trisecondary butoxide and aluminum acetylacetonate, were used as precursors to coat tubes of varying diameters. The morphology and uniformity of the coatings were characterized by electron microscopy and energy-dispersive x-ray spectroscopy. The coating was characterized by x-ray photoelectron spectroscopy to obtain the surface chemical composition. This is the first study conducted to examine the application of MOCVD to coat internal surfaces of tubes with varying diameters. In the third part of the study, the metal oxide coatings, alumina from aluminum acetylacetonate, alumina from aluminum trisecondary butoxide, zirconia from zirconium acetylacetonate, tantalum oxide from tantalum pentaethoxide and the metal coating, platinum from platinum acetylacetonate were deposited by MOCVD on AISI304. The chemical composition and the surface acidity of the coatings were characterized by x-ray photoelectron spectroscopy. The morphology of the coatings was characterized by electron microscopy. The coated substrates were tested in the presence of heated Jet-A in a flow reactor to evaluate their effectiveness in inhibiting the solid deposit formation. All coatings inhibited the formation of metal sulfides and the carbonaceous solid deposits formed by metal catalysis. The coatings also delayed the accumulation of solid carbonaceous deposits. In particular, it has been confirmed that the surface acidity of the metal oxide coatings affects the formation of carbonaceous deposits. Bimolecular addition reactions promoted by the Bronsted acid sites appear to lead to the formation of carbonaceous solid deposits depending on the surface acidity of the coatings. In the last part of the study, the residual carbon was incorporated in the zirconia coating by deposition with and without oxygen. As carbon surface is less active towards coke deposition, presence of residual carbon in the coating was expected to reduce its activity towards carbon deposition. The residual carbon in the coating was characterized by Raman spectroscopy and thermal analysis. However, it has been observed that residual carbon in the coating beyond a certain concentration compromises the integrity of the coating during the process of cooling the substrate from deposition temperature to room temperature. It has been found that residual carbon in the zirconia coating does not appear to affect the activity of the surface towards carbon deposition.

Bioinspired Polyelectrolyte-Assembled Graphene-Oxide-Coated C18 Composite Solid-Phase Microextraction Fibers for In Vivo Monitoring of Acidic Pharmaceuticals in Fish.

PubMed

Qiu, Junlang; Chen, Guosheng; Liu, Shuqin; Zhang, Tianlang; Wu, Jiayi; Wang, Fuxin; Xu, Jianqiao; Liu, Yan; Zhu, Fang; Ouyang, Gangfeng

2016-06-07

A novel solid-phase microextraction (SPME) fiber was prepared by gluing poly(diallyldimethylammonium chloride) (PDDA) assembled graphene oxide (GO)-coated C18 composite particles (C18@GO@PDDA) onto a quartz fiber with polyaniline (PANI). The fiber surface coating was sequentially modified with bioinspired polynorepinephrine, which provided a smooth biointerface and makes the coating suitable for in vivo sampling. The novel custom-made coating was used to extract acidic pharmaceuticals, and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was employed for analysis. The custom-made coating exhibited a much higher extraction efficiency than the previously used commercial polydimethylsiloxane (PDMS) and polyacrylate (PA) coatings. The custom-made coating also possessed satisfactory stability (the relative standard deviations (RSDs) ranged from 1.60% to 10.3% for six sampling-desorption cycles), interfiber reproducibility (the RSDs ranged from 2.61% to 11.5%), and resistance to matrix effects. The custom-made fibers were used to monitor the presence of acid pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities (limits of detection ranged from 0.13 ng/g to 7.56 ng/g) were achieved. The accuracies were verified by the comparison with liquid extraction. Moreover, the novel fibers were successfully used to monitor the presence of acidic pharmaceuticals in living fish, which demonstrated that the custom-made fibers were feasible for possible long-term in vivo continuous pharmaceutical monitoring.

Method of lift-off patterning thin films in situ employing phase change resists

DOEpatents

Bahlke, Matthias Erhard; Baldo, Marc A; Mendoza, Hiroshi Antonio

2014-09-23

Method for making a patterned thin film of an organic semiconductor. The method includes condensing a resist gas into a solid film onto a substrate cooled to a temperature below the condensation point of the resist gas. The condensed solid film is heated selectively with a patterned stamp to cause local direct sublimation from solid to vapor of selected portions of the solid film thereby creating a patterned resist film. An organic semiconductor film is coated on the patterned resist film and the patterned resist film is heated to cause it to sublime away and to lift off because of the phase change.

Solid-phase microextraction may catalize hydrogenation when using hydrogen as carrier in gas chromatography.

PubMed

Fiorini, D; Boarelli, M C

2016-07-01

When hydrogen is used as carrier gas, carbon-carbon double bonds may be hydrogenated in the hot gas chromatograph (GC) injector if introduced by solid-phase microextraction (SPME). SPME fibers coated with polydimethylsiloxane (PDMS)/carboxen/divinylbenzene (DVB), PDMS/carboxen, polyacrylate, PDMS/DVB and PDMS on fused silica, stableflex or metal alloy core have been tested with fatty acid methyl esters (FAMEs) from olive oil. Using coatings containing DVB, hydrogenation took place with high conversion rates (82.0-92.9%) independently of the core material. With all fibers having a metal core, hydrogenation was observed to a certain extent (27.4-85.3%). PDMS, PDMS/carboxen and polyacrylate coated fibers with a fused silica or stableflex core resulted in negligible hydrogenation (0.2-2.5%). The occurrence of hydrogenation was confirmed also with other substances containing carbon-carbon double bonds (n-alkenes, alkenoic acids, mono- and polyunsaturated fatty acid methyl and ethyl esters). Copyright © 2016 Elsevier B.V. All rights reserved.

Multi-layer coatings for bipolar rechargeable batteries with enhanced terminal voltage

DOEpatents

Farmer, Joseph C.; Kaschmitter, James; Pierce, Steve

2017-06-06

A method for producing a multi-layer bipolar coated cell according to one embodiment includes applying a first active cathode material above a substrate to form a first cathode; applying a first solid-phase ionically-conductive electrolyte material above the first cathode to form a first electrode separation layer; applying a first active anode material above the first electrode separation layer to form a first anode; applying an electrically conductive barrier layer above the first anode; applying a second active cathode material above the anode material to form a second cathode; applying a second solid-phase ionically-conductive electrolyte material above the second cathode to form a second electrode separation layer; applying a second active anode material above the second electrode separation layer to form a second anode; and applying a metal material above the second anode to form a metal coating section. In another embodiment, the anode is formed prior to the cathode. Cells are also disclosed.

Comparison of different coatings in solid-phase microextraction for the determination of organochlorine pesticides in ground water.

PubMed

Pérez-Trujillo, J P; Frías, S; Conde, J E; Rodríguez-Delgado, M A

2002-07-19

A solid-phase microextraction (SPME) procedure using three commercialised fibers (Carbowax-divinylbenzene, Carboxen-polydimethylsiloxane and divinylbenzene-Carboxen-polydimethylsiloxane) is presented for the determination of a selected group of organochlorine compounds in water samples. The extraction performances of these compounds were compared using fibers with two and three coatings. The optimal experimental procedures for the adsorption and desorption of pesticides were determined. The limits of detection with the divinylbenzene-Carboxen-polydimethylsiloxane fiber at levels below ng l(-1) were similar or lower than values presented in the literature for several of these compounds using polydimethylsiloxane fiber. The advantages of using this fiber, such as no salt addition, are discussed. Finally, the optimised procedures were applied successfully for the determination of these compounds in polluted ground water samples.

Plasma sprayed manganese-cobalt spinel coatings: Process sensitivity on phase, electrical and protective performance

NASA Astrophysics Data System (ADS)

Han, Su Jung; Pala, Zdenek; Sampath, Sanjay

2016-02-01

Manganese cobalt spinel (Mn1.5Co1.5O4, MCO) coatings are prepared by the air plasma spray (APS) process to examine their efficacy in serving as protective coatings from Cr-poisoning of the cathode side in intermediate temperature-solid oxide fuel cells (IT-SOFCs). These complex oxides are susceptible to process induced stoichiometric and phase changes which affect their functional performance. To critically examine these effects, MCO coatings are produced with deliberate modifications to the spray process parameters to explore relationship among process conditions, microstructure and functional properties. The resultant interplay among particle thermal and kinetic energies are captured through process maps, which serve to characterize the parametric effects on properties. The results show significant changes to the chemistry and phase composition of the deposited material resulting from preferential evaporation of oxygen. Post deposition annealing recovers oxygen in the coatings and allows partial recovery of the spinel phase, which is confirmed through thermo-gravimetric analysis (TGA)/differential scanning calorimetry (DSC), X-ray Diffraction (XRD), and magnetic hysteresis measurements. In addition, coatings with high density after sintering show excellent electrical conductivity of 40 S cm-1 at 800 °C while simultaneously providing requisite protection characteristics against Cr-poisoning. This study provides a framework for optimal evaluation of MCO coatings in intermediate temperature SOFCs.

Bioinspired polydopamine sheathed nanofibers for high-efficient in vivo solid-phase microextraction of pharmaceuticals in fish muscle.

PubMed

Xu, Jianqiao; Huang, Shuyao; Wu, Rongben; Jiang, Ruifen; Zhu, Fang; Wang, Jing; Ouyang, Gangfeng

2015-03-17

In this study, electrospun nanofibers were used as solid-phase microextraction (SPME) fiber coatings after substituting the water-soluble sheath of the emulsion electrospun polystyrene (PS)@Plurinic F-127 core-sheath nanofibers with biocompatible and water-stable polydopamine (PDA) and subsequently being appropriately cross-linked with glutaraldehyde (GA) to enhance the strength of the electrospun architecture. The novel custom-made PS@PDA-GA coating was wettable in aqueous solutions and thus exhibited much higher extraction efficiency than the nonsheathed PS nanofiber coating and the thicker polydimethylsiloxane (PDMS) coating. The novel coating also possessed excellent stability (relative standard deviations (RSDs) less than 7.3% for six sampling-desorption cycles), interfiber reproducibility (RSDs less than 14.3%), and antibiofouling ability, which were beneficial for in vivo sampling. The PS@PDA-GA fiber was used to monitor pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities with the limits of detection in the range of 1.1 (mefenamic acid) to 8.9 (fluoxetine) ng·g(-1) and comparable accuracies to liquid extraction were achieved. In general, this study explored a convenient and effective method to sheath nanofibers for high-efficient in vivo SPME of analytes of interest in semisolid tissues.

Aggregation in complex triacylglycerol oils: coarse-grained models, nanophase separation, and predicted x-ray intensities.

PubMed

Quinn, Bonnie; Peyronel, Fernanda; Gordon, Tyler; Marangoni, Alejandro; Hanna, Charles B; Pink, David A

2014-11-19

Triacylglycerols (TAGs) are biologically important molecules which form crystalline nanoplatelets (CNPs) and, ultimately, fat crystal networks in edible oils. Characterizing the self-assembled hierarchies of these networks is important to understanding their functionality and oil binding capacity. We have modelled CNPs in multicomponent oils and studied their aggregation. The oil comprises (a) a liquid component, and (b) components which phase separately on a nano-scale (nano-phase separation) to coat the surfaces of the CNPs impenetrably, either isotropically or anisotropically, with either liquid-like coatings or crystallites, forming a coating of thickness ?. We modelled three cases: (i) liquid?liquid nano-phase separation, (ii) solid?liquid nano-phase separation, with CNPs coated isotropically, and (iii) CNPs coated anisotropically. The models were applied to mixes of tristearin and triolein with fully hydrogenated canola oil, shea butter with high oleic sunflower oil, and cotton seed oil. We performed Monte Carlo simulations, computed structure functions and concluded: (1) three regimes arose: (a) thin coating regime, Δ < 0.0701 u (b) transition regime, 0.0701 u ≤ Δ ≤ 0.0916 u and (c) thick coating regime, Δ > 0.0916 u. (arbitrary units, u) (2) The thin coating regime exhibits 1D TAGwoods, which aggregate, via DLCA/RLCA, into fractal structures which are uniformly distributed in space. (3) In the thick coating regime, for an isotropic coating, TAGwoods are not formed and coated CNPs will not aggregate but will be uniformly distributed in space. For anisotropic coating, TAGwoods can be formed and might form 1D strings but will not form DLCA/RLCA clusters. (4) The regimes are, approximately: thin coating, 0 < Δ < 7.0 nm transition regime, 7.0 < Δ < 9.2 nm and thick coating, Δ > 9.2 nm (5) The minimum minority TAG concentration required to undergo nano-phase separation is, approximately, 0.29% (thin coatings) and 0.94% (thick coatings). Minority components can have substantial effects upon aggregation for concentrations less than 1%.

Development of a fiber coating based on molecular sol-gel imprinting technology for selective solid-phase micro extraction of caffeine from human serum and determination by gas chromatography/mass spectrometry.

PubMed

Rajabi Khorrami, Afshin; Rashidpur, Amene

2012-05-21

In this work, a molecular sol-gel imprinting approach has been introduced to produce a fiber coating for selective direct immersion solid-phase microextraction (SPME) of caffeine. The polymerization mixture was composed of vinyl trimethoxysilane and methacrylic acid as vinyl sol-gel precursor and functional monomer, respectively. Caffeine was used as template molecule during polymerization process. The prepared fibers could be coupled directly to gas chromatography/mass spectrometry (GC/MS) and used for trace analysis of caffeine in a complex sample such as human serum. The parameters influencing SPME such as time, temperature and stirring speed were optimized. The prepared coating showed good selectivity towards caffeine in the presence of some structurally related compounds. Also, it offered high imprinting capability in comparison to bare fiber and non-imprinted coating. Linear range for caffeine detection was 1-80 μg mL(-1) and the limit of detection was 0.1 μg mL(-1). The intra-day and inter-day precisions of the peak areas for five replicates were 10 and 16%, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Octadecyltrimethoxysilane functionalized ZnO nanorods as a novel coating for solid-phase microextraction with strong hydrophobic surface.

PubMed

Zeng, Jingbin; Liu, Haihong; Chen, Jinmei; Huang, Jianli; Yu, Jianfeng; Wang, Yiru; Chen, Xi

2012-09-21

In this paper, we have, for the first time, proposed an approach by combining self-assembled monolayers (SAMs) and nanomaterials (NMs) for the preparation of novel solid-phase microextraction (SPME) coatings. The self-assembly of octadecyltrimethoxysilane (OTMS) on the surface of ZnO nanorods (ZNRs) was selected as a model system to demonstrate the feasibility of this approach. The functionalization of OTMS on the surface of ZNRs was characterized and confirmed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The OTMS-ZNRs coated fiber exhibited stronger hydrophobicity after functionalization, and its extraction efficiency for non-polar benzene homologues was increased by a factor of 1.5-3.6 when compared to a ZNRs fiber with almost identical thickness and façade. In contrast, the extraction efficiency of the OTMS-ZNRs coated fiber for polar aldehydes was 1.6-4.0-fold lower than that of the ZNRs coated fiber, further indicating its enhanced surface hydrophobicity. The OTMS-ZNRs coated fiber revealed a much higher capacity upon increasing the OTMS layer thickness to 5 μm, leading to a factor of 12.0-13.4 and 1.8-2.5 increase in extraction efficiency for the benzene homologues relative to a ZNRs coated fiber and a commercial PDMS fiber, respectively. The developed HS-SPME-GC method using the OTMS-ZNRs coated fiber was successfully applied to the determination of the benzene homologues in limnetic water samples with recovery ranging from 83 to 113% and relative standard deviations (RSDs) of less than 8%.

CVD method of forming self-lubricating composites

DOEpatents

Besmann, T.M.; Blau, P.J.; Lee, W.Y.; Bae, Y.W.

1998-12-01

An article having a multiphase composite lubricant coating of a hard refractory matrix phase of titanium nitride dispersed with particles of a solid lubricating phase of molybdenum disulfide is prepared by heating the article to temperatures between 350 and 850 C in a reaction vessel at a reduced pressure and passing a gaseous mixture of Ti((CH{sub 3}){sub 2}N){sub 4}, MoF{sub 6}, H{sub 2}S and NH{sub 3} over the heated article forming a multiphase composite lubricant coating on the article. 1 fig.

CVD method of forming self-lubricating composites

DOEpatents

Besmann, Theodore M.; Blau, Peter J.; Lee, Woo Y.; Bae, Yong W.

1998-01-01

An article having a multiphase composite lubricant coating of a hard refractory matrix phase of titanium nitride dispersed with particles of a solid lubricating phase of molybdenum disulfide is prepared by heating the article to temperatures between 350.degree. and 850.degree. C. in a reaction vessel at a reduced pressure and passing a gaseous mixture of Ti((CH.sub.3).sub.2 N).sub.4, MoF.sub.6, H.sub.2 S and NH.sub.3 over the heated article forming a multiphase composite lubricant coating on the article.

Atmospheric Plasma Spraying Low-Temperature Cathode Materials for Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Harris, J.; Kesler, O.

2010-01-01

Atmospheric plasma spraying (APS) is attractive for manufacturing solid oxide fuel cells (SOFCs) because it allows functional layers to be built rapidly with controlled microstructures. The technique allows SOFCs that operate at low temperatures (500-700 °C) to be fabricated by spraying directly onto robust and inexpensive metallic supports. However, standard cathode materials used in commercial SOFCs exhibit high polarization resistances at low operating temperatures. Therefore, alternative cathode materials with high performance at low temperatures are essential to facilitate the use of metallic supports. Coatings of lanthanum strontium cobalt ferrite (LSCF) were fabricated on steel substrates using axial-injection APS. The thickness and microstructure of the coating layers were evaluated, and x-ray diffraction analysis was performed on the coatings to detect material decomposition and the formation of undesired phases in the plasma. These results determined the envelope of plasma spray parameters in which coatings of LSCF can be manufactured, and the range of conditions in which composite cathode coatings could potentially be manufactured.

Preparation of novel alumina nanowire solid-phase microextraction fiber coating for ultra-selective determination of volatile esters and alcohols from complicated food samples.

PubMed

Zhang, Zhuomin; Ma, Yunjian; Wang, Qingtang; Chen, An; Pan, Zhuoyan; Li, Gongke

2013-05-17

A novel alumina nanowire (ANW) solid-phase microextraction (SPME) fiber coating was prepared by a simple and rapid anodization-chemical etching method for ultra-selective determination of volatile esters and alcohols from complicated food samples. Preparation conditions for ANW SPME fiber coating including corrosion solution concentration and corrosion time were optimized in detail for better surface morphology and higher surface area based on scanning electron microscope (SEM). Under the optimum conditions, homogeneous alumina nanowire structure of ANW SPME fiber coating was achieved with the average thickness of 20 μm around. Compared with most of commercial SPME fiber coatings, ANW SPME fiber coatings achieved the higher extraction capacity and special selectivity for volatile esters and alcohols. Finally, an efficient gas sampling technique based on ANW SPME fiber coating as the core was established and successfully applied for the ultra-selective determination of trace volatile esters and alcohols from complicated banana and fermented glutinous rice samples coupled with gas chromatography/mass spectrometry (GC/MS) detection. It was interesting that 25 esters and 2 alcohols among 30 banana volatile organic compounds (VOCs) identified and 4 esters and 7 alcohols among 13 identified VOCs of fermented glutinous rice were selectively sampled by ANW SPME fiber coatings. Furthermore, new analytical methods for the determination of some typical volatile esters and alcohols from banana and fermented glutinous rice samples at specific storage or brewing phases were developed and validated. Good recoveries for banana and fermented glutinous rice samples were achieved in range of 108-115% with relative standard deviations (RSDs) of 2.6-6.7% and 80.0-91.8% with RSDs of 0.3-1.3% (n=3), respectively. This work proposed a novel and efficient gas sampling technique of ANW SPME which was quite suitable for ultra-selectively sampling trace volatile esters and alcohols from complicated food samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Preparation and application of carbon nanotubes/poly(o-toluidine) composite fibers for the headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and xylenes.

PubMed

Behzadi, Mansoureh; Noroozian, Ebrahim; Mirzaei, Mohammad

2013-11-01

A novel nanocomposite coating of poly(o-toluidine) and oxidized multiwalled CNTs (MWCNTs, where CNTs is carbon nanotubes) was electrochemically prepared on a stainless-steel wire. The applicability of the fiber was assessed for the headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and xylenes in aqueous samples followed by GC with flame ionization detection. In order to obtain an adherent and stable composite coating, several experimental parameters related to the coating process, such as polymerization potential and time, and the concentration of o-toluidine and oxidized MWCNTs were optimized. The combination of MWCNTs and polymer in a nanocomposite form presents desirable opportunities to produce materials for new applications. The effects of various parameters on the efficiency of the headspace solid-phase microextraction process, such as desorption temperature and time, extraction temperature and time, and ionic strength were also investigated. At the optimum conditions, LODs were 0.03-0.06 μg/L. The method showed linearity in the range of 0.5-300 μg/L with coefficients of determination >0.99. The intraday and interday RSDs obtained at a 5 μg/L concentration level (n = 5) using a single fiber were 1.2-5.2 and 3.2-7.5%, respectively. The fiber-to-fiber RSD (%; n = 3) at 5 μg/L was 6.1-9.2%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Amine-functionalized MIL-53(Al)-coated stainless steel fiber for efficient solid-phase microextraction of synthetic musks and organochlorine pesticides in water samples.

PubMed

Xie, Lijun; Liu, Shuqin; Han, Zhubing; Jiang, Ruifen; Zhu, Fang; Xu, Weiqin; Su, Chengyong; Ouyang, Gangfeng

2017-09-01

The fiber coating is the key part of the solid-phase microextraction (SPME) technique, and it determines the sensitivity, selectivity, and repeatability of the analytical method. In this work, amine (NH 2 )-functionalized material of Institute Lavoisier (MIL)-53(Al) nanoparticles were successfully synthesized, characterized, and applied as the SPME fiber coating for efficient sample pretreatment owing to their unique structures and excellent adsorption properties. Under optimized conditions, the NH 2 -MIL-53(Al)-coated fiber showed good precision, low limits of detection (LODs) [0.025-0.83 ng L -1 for synthetic musks (SMs) and 0.051-0.97 ng L -1 for organochlorine pesticides (OCPs)], and good linearity. Experimental results showed that the NH 2 -MIL-53(Al) SPME coating was solvent resistant and thermostable. In addition, the extraction efficiencies of the NH 2 -MIL-53(Al) coating for SMs and OCPs were higher than those of commercially available SPME fiber coatings such as polydimethylsiloxane, polydimethylsiloxane-divinylbenzene, and polyacrylate. The reasons may be that the analytes are adsorbed on NH 2 -MIL-53(Al) primarily through π-π interactions, electron donor-electron acceptor interactions, and hydrogen bonds between the analytes and organic linkers of the material. Direct immersion (DI) SPME-gas chromatography-mass spectrometry methods based on NH 2 -MIL-53(Al) were successfully applied for the analysis of tap and river water samples. The recoveries were 80.3-115% for SMs and 77.4-117% for OCPs. These results indicate that the NH 2 -MIL-53(Al) coating may be a promising alternative to SPME coatings for the enrichment of SMs and OCPs.

Anticorrosive organic/inorganic hybrid coatings

NASA Astrophysics Data System (ADS)

Gao, Tongzhai

Organic/inorganic hybrid coating system was developed for anticorrosion applications using polyurea, polyurethane or epoxide as the organic phase and polysiloxane, formed by sol-gel process, as the inorganic phase. Polyurea/polysiloxane hybrid coatings were formulated and moisture cured using HDI isocyanurate, alkoxysilane-functionalized HDI isocyanurate, and tetraethyl orthosilicate (TEOS) oligomers. Two urethanes were prepared using the same components as abovementioned in addition to the oligoesters derived from either cyclohexane diacids (CHDA) and 2-butyl-2-ethyl-1,3-propanediol (BEPD) or adipic acid (AA), isophthalic acid (IPA), 1,6-hexanediol (HD), and trimethylol propane (TMP). Accelerated weathering and outdoor exposure were performed to study the weatherability of the polyurethane/polysiloxane hybrid coating system. FTIR and solid-state 13C NMR revealed that the degradation of the hybrid coatings occurred at the urethane and ester functionalities of the organic phase. DMA and DSC analyses showed the glass transition temperature increased and broadened after weathering. SEM was employed to observe the change of morphology of the hybrid coatings and correlated with the gloss variation after weathering. Rutile TiO2 was formulated into polyurethane/polysiloxane hybrid coatings in order to investigate the effect of pigmentation on the coating properties and the sol-gel precursor. Chemical interaction between the TiO2 and the sol-gel precursor was investigated using solid-state 29Si NMR and XPS. The morphology, mechanical, viscoelastic, thermal properties of the pigmented coatings were evaluated as a function of pigmentation volume concentration (PVC). Using AFM and SEM, the pigment were observed to be well dispersed in the polymer matrix. The thermal stability, the tensile modulus and strength of the coatings were enhanced with increasing PVC, whereas the pull-off adhesion and flexibility were reduced with increasing PVC. Finally, the pigmented coatings were evaluated by electrochemical impedance spectroscopy (EIS) and the results showed that 10 wt% pigmentation improved the corrosion resistance of the entire coating system. The effect of pigmentation on epoxide/polysiloxane hybrid coatings was also investigated. The epoxide was successfully modified using 3-(triethoxysilyl) propyl isocyanate (TEOSPI) as indicated by FTIR and NMR. Good dispersion of the pigment particles was achieved as revealed by the SEM images. The tensile modulus, tensile strength, pencil hardness and thermal stability of the hybrid coatings were improved while the flexibility and pull-off adhesion were deteriorated when increasing PVC.

Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings

NASA Astrophysics Data System (ADS)

Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

2010-03-01

Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

Hot Corrosion of Yttrium Stabilized Zirconia Coatings Deposited by Air Plasma Spray on a Nickel-Based Superalloy

NASA Astrophysics Data System (ADS)

Vallejo, N. Diaz; Sanchez, O.; Caicedo, J. C.; Aperador, W.; Zambrano, G.

In this research, the electrochemical impedance spectroscopy (EIS) and Tafel analysis were utilized to study the hot corrosion performance at 700∘C of air plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) coatings with a NiCrAlY bond coat grown by high velocity oxygen fuel spraying (HVOF), deposited on an INCONEL 625 substrate, in contact with corrosive solids salts as vanadium pentoxide V2O5 and sodium sulfate Na2SO4. The EIS data were interpreted based on proposed equivalent electrical circuits using a suitable fitting procedure performed with Echem AnalystTM Software. Phase transformations and microstructural development were examined using X-ray diffraction (XRD), with Rietveld refinement for quantitative phase analysis, scanning electron microscopy (SEM) was used to determinate the coating morphology and corrosion products. The XRD analysis indicated that the reaction between sodium vanadate (NaVO3) and yttrium oxide (Y2O3) produces yttrium vanadate (YVO4) and leads to the transformation from tetragonal to monoclinic zirconia phase.

Influence of polydimethylsiloxane outer coating and packing material on analyte recovery in dual-phase headspace sorptive extraction.

PubMed

Bicchi, Carlo; Cordero, Chiara; Liberto, Erica; Sgorbini, Barbara; David, Frank; Sandra, Pat; Rubiolo, Patrizia

2007-09-14

Dual phase twisters (DP twisters), consisting of a polydimethylsiloxane (PDMS) outer coating and a second complementary (ad)sorbent as inner packing, have recently been shown to extend the applicability of headspace sorptive extraction (HSSE). In comparison to HSSE using PDMS only, the recovery of analytes from the headspace of a solid or liquid matrix is increased by combining the concentration capabilities of two sampling materials operating on different mechanisms (sorption and adsorption). This study compares the performance of DP twisters consisting of different PDMS outer coatings and different packing materials, including Tenax GC, a bisphenol-PDMS copolymer, Carbopack coated with 5% of Carbowax and beta-cyclodextrin, for the analysis of the headspace of roasted Arabica coffee, dried sage leaves and an aqueous test mixture containing compounds with different water solubility, acidity, polarity and volatility as test samples. In general, DP twisters showed a higher concentration capability than the corresponding conventional PDMS twisters for the analytes considered. The highest recoveries were obtained with DP twisters consisting of 0.2mm thick PDMS coating combined with Tenax GC, a bisphenol-PDMS copolymer and Carbopack coated with 5% of Carbowax as inner adsorption phase.

Polymeric ionic liquid coatings versus commercial solid-phase microextraction coatings for the determination of volatile compounds in cheeses.

PubMed

Trujillo-Rodríguez, María J; Yu, Honglian; Cole, William T S; Ho, Tien D; Pino, Verónica; Anderson, Jared L; Afonso, Ana M

2014-04-01

The extraction performance of four polymeric ionic liquid (PIL)-based solid-phase microextraction (SPME) coatings has been studied and compared to that of commercial SPME coatings for the extraction of 16 volatile compounds in cheeses. The analytes include 2 free fatty acids, 2 aldehydes, 2 ketones and 10 phenols and were determined by headspace (HS)-SPME coupled to gas chromatography (GC) with flame-ionization detection (FID). The PIL-based coatings produced by UV co-polymerization were more efficient than PIL-based coatings produced by thermal AIBN polymerization. Partition coefficients of analytes between the sample and the coating (Kfs) were estimated for all PIL-based coatings and the commercial SPME fiber showing the best performance among the commercial fibers tested: carboxen-polydimethylsyloxane (CAR-PDMS). For the PIL-based fibers, the highest K(fs) value (1.96 ± 0.03) was obtained for eugenol. The normalized calibration slope, which takes into account the SPME coating thickness, was also used as a simpler approximate tool to compare the nature of the coating within the determinations, with results entirely comparable to those obtained with estimated K(fs) values. The PIL-based materials obtained by UV co-polymerization containing the 1-vinyl-3-hexylimidazolium chloride IL monomer and 1,12-di(3-vinylimiazolium)dodecane dibromide IL crosslinker exhibited the best performance in the extraction of the select analytes from cheeses. Despite a coating thickness of only 7 µm, this copolymeric sorbent coating was capable of quantitating analytes in HS-SPME in a 30 to 2000 µg L(-1) concentration range, with correlation coefficient (R) values higher than 0.9938, inter-day precision values (as relative standard deviation in %) varying from 6.1 to 20%, and detection limits down to 1.6 µg L(-1). Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of polychlorinated biphenyls in ocean water and bovine milk using crosslinked polymeric ionic liquid sorbent coatings by solid-phase microextraction.

PubMed

Joshi, Manishkumar D; Ho, Tien D; Cole, William T S; Anderson, Jared L

2014-01-01

Crosslinked polymeric ionic liquid (PIL)-based sorbent coatings were employed in the extraction of 21 polychlorinated biphenyls (PCBs) from ocean water and bovine milk using solid-phase microextraction (SPME). The extraction temperature, time, and concentration of sodium chloride added to the matrix were optimized in order to determine the best extraction conditions for the extraction of PCBs. The analytical performance of the crosslinked PIL-based SPME fibers was compared with a commercial 7 µm polydimethylsiloxane (PDMS) fiber using gas chromatography (GC) employing an electron capture detector (ECD) and mass spectrometric detection (MS). Higher sensitivities for PCBs were achieved using PIL-based fibers when compared to PDMS fiber due to the incorporation of benzyl moieties into the PIL structures. The limits of detection (LOD) for all PCBs were determined to be in the low ng L(-1) range using the three studied coatings. Recovery studies were performed for PCBs in ocean water and bovine milk to validate the applicability of the current SPME method. © 2013 Published by Elsevier B.V.

Fabrication of Cu2ZnSn(S,Se)4 (CZTSSe) absorber films based on solid-phase synthesis and blade coating processes

NASA Astrophysics Data System (ADS)

Ma, Ruixin; Yang, Fan; Li, Shina; Zhang, Xiaoyong; Li, Xiang; Cheng, Shiyao; Liu, Zilin

2016-04-01

CZTSSe is an important earth abundant collection of materials for the development of low cost and high efficiency thin film solar cells. This work developed a simple non-vacuum-based route to fabricate CZTSSe absorber films. This was demonstrated by first synthesizing Cu2ZnSnS4 (CZTS) nano-crystalline based on solid-phase synthesis. Then a stable colloidal ink composed of CZTS nano-crystalline was blade coated on Mo-coated substrates followed by an annealing process under Ar atmosphere. After CZTS films formation, the films were sintered into CZTSSe absorber films by exposing them under Selenium vapor. The formation of a kesterite type CZTS was confirmed using X-ray diffraction and Raman scattering measurements. The band gap of CZTSSe absorber films was determined to be 1.26 eV, which was appropriate for use as an absorber layer in thin film solar cells. The CZTSSe absorber films showed a good photovoltatic performance, demonstrating this simple approach had great potential for CZTSSe solar cell production.

Thin metal organic frameworks coatings by cathodic electrodeposition for solid-phase microextraction and analysis of trace exogenous estrogens in milk.

PubMed

Lan, Hangzhen; Pan, Daodong; Sun, Yangying; Guo, Yuxing; Wu, Zhen

2016-09-21

Cathodic electrodeposition (CED) has received great attention in metal-organic frameworks (MOFs) synthesis due to its distinguished properties including simplicity, controllability, mild synthesis conditions, and product continuously. Here, we report the fabrication of thin (Et3NH)2Zn3(BDC)4 (E-MOF-5) film coated solid phase microextraction (SPME) fiber by a one-step in situ cathodic electrodeposition strategy. Several etched stainless steel fibers were placed in parallel in order to achieve simultaneously electrochemical polymerization. The influence of different polymerization parameters Et3NHCl concentration and polymerization time were evaluated. The proposed method requires only 20 min for the preparation of E-MOF-5 coating. The optimum coating showed excellent thermal stability and mechanical durability with a long lifetime of more than 120 repetitions SPME operations, and also exhibited higher extraction selectivity and capacity to four estrogens than commonly-used commercial PDMS coating. The limits of detection for the estrogens were 0.17-0.56 ng mL(-1). Fiber-to-fiber reproducibility (n = 8) was in the respective ranges of 3.5%-6.1% relative standard deviation (RSD) for four estrogens for triplicate measurements at 200 ng mL(-1). Finally, the (E-MOF-5) coated fiber was evaluated for ethinylestradiol (EE2), bisphenol A (BPA), diethylstilbestrol (DES), and hexestrol (HEX) extraction in the spiked milk samples. The extraction performance of this new coating was satisfied enough for repeatable use without obvious decline. Copyright © 2016 Elsevier B.V. All rights reserved.

Sensitive and selective determination of polycyclic aromatic hydrocarbons in mainstream cigarette smoke using a graphene-coated solid-phase microextraction fiber prior to GC/MS.

PubMed

Wang, Xiaoyu; Wang, Yuan; Qin, Yaqiong; Ding, Li; Chen, Yi; Xie, Fuwei

2015-08-01

A simple method has been developed for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in mainstream cigarette smoke. The procedure is based on employing a homemade graphene-coated solid-phase microextraction (SPME) fiber for extraction prior to GC/MS. In comparison to commercial 100-μm poly(dimethyl siloxane) (PDMS) fiber, the graphene-coated SPME fiber exhibits advantageous cleanup and preconcentration efficiencies. By collecting the particulate phase 5 cigarettes, the LODs and LOQs of 16 target PAHs were 0.02-0.07 and 0.07-0.22 ng/cigarette, respectively, and all of the linear correlation efficiencies were larger than 0.995. The validation results also indicate that the method has good repeatability (RSD between 4.2% and 9.5%) and accuracy (spiked recoveries between 80% and 110%). The developed method was applied to analyze two Kentucky reference cigarettes (1R5F and 3R4F) and six Chinese brands of cigarettes. In addition, the PAH concentrations in the particulate phase of the smoke from the 1R5F Kentucky cigarettes were in good agreement with recently reported results. Due to easy operation and good validation results, this SPME-GC/MS method may be an excellent alternative for trace analysis of PAHs in cigarette smoke. Copyright © 2015 Elsevier B.V. All rights reserved.

Combined synthesis and in situ coating of nanoparticles in the gas phase

NASA Astrophysics Data System (ADS)

Lähde, Anna; Raula, Janne; Kauppinen, Esko I.

2008-12-01

Combined gas phase synthesis and coating of sodium chloride (NaCl) and lactose nanoparticles has been developed using an aerosol flow reactor. Nano-sized core particles were produced by the droplet-to-particle method and coated in situ by the physical vapour deposition of L-leucine vapour. The saturation of L-leucine in the reactor determined the resulting particle size and size distribution. In general, particle size increased with the addition of L-leucine and notable narrowing of the core particle size distribution was observed. In addition, homogeneous nucleation of the vapour, i.e. formation of pure L-leucine particles, was observed depending on the saturation conditions of L-leucine as well as the core particle characteristics. The effects of core particle properties, i.e. size and solid-state characteristics, on the coating process were studied by comparing the results for coated NaCl and lactose particles. During deposition, L-leucine formed a uniform coating on the surface of the core particles. The coating stabilised the nanoparticles and prevented the sintering of particles during storage.

A comparative physico-chemical study of chlorapatite and hydroxyapatite: from powders to plasma sprayed thin coatings.

PubMed

Demnati, I; Grossin, D; Combes, C; Parco, M; Braceras, I; Rey, C

2012-10-01

Due to their bioactivity and osteoconductivity, hydroxyapatite (HA) plasma sprayed coatings have been widely developed for orthopedic uses. However, the thermodynamic instability of HA leads frequently to a mixture of phases which limit the functional durability of the coating. This study investigates the plasma spraying of chlorapatite (ClA) powder, known to melt without decomposition, onto pure titanium substrates using a low energy plasma spray system (LEPS). Pure ClA powder was prepared by a solid gas reaction at 950 °C and thermogravimetric analysis showed the good thermal stability of ClA powder in the range 30-1400 °C compared to that of the HA powder. Characterization of ClA coating showed that ClA had a very high crystalline ratio and no other crystalline phase was detected in the coating. HA and ClA coatings composition, microstructure and in vitro bioactivity potential were studied, compared and discussed. In vitro SBF test on HA and ClA coatings revealed the formation of a poorly crystalline apatite on the coating surface suggesting that we could expect a good osteoconductivity especially for the ClA coating prepared by the LEPS system.

Silica-based ionogels: nanoconfined ionic liquid-rich fibers for headspace solid-phase microextraction coupled with gas chromatography-barrier discharge ionization detection.

PubMed

Pena-Pereira, Francisco; Marcinkowski, Lukasz; Kloskowski, Adam; Namieśnik, Jacek

2014-12-02

In this work, hybrid silica-based materials with immobilized ionic liquids (ILs) were prepared by sol-gel technology and evaluated as solid-phase microextraction (SPME) fiber coatings. High loadings of the IL 1-methyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide ([C4MIM][TFSI]) were confined within the hybrid network. Coatings composition and morphology were evaluated using scanning electron microscopy and energy dispersive X-ray spectrometry. The obtained ionogel SPME fibers exhibited high extractability for aromatic volatile compounds, yielding good sensitivity and precision when combined with a gas chromatograph with barrier ionization discharge (GC-BID) detection. A central composite design was used for assessing the effect of experimental parameters on the extraction process. Under optimized conditions, the proposed ionogel SPME fiber coatings enabled the achievement of excellent enrichment factors (up to 7400). The limits of detection (LODs) were found in the range 0.03-1.27 μg L(-1), whereas the repeatability and fiber-to-fiber reproducibility were 5.6% and 12.0% on average, respectively. Water samples were analyzed by the proposed methodology, showing recovery values in the range of 88.7-113.9%. The results obtained in this work suggest that ionogels can be promising coating materials for future applications of SPME and related sample preparation techniques.

Solid phase microextraction of phthalic acid esters from vegetable oils using iron (III)-based metal-organic framework/graphene oxide coating.

PubMed

Zhang, Shuaihua; Yang, Qian; Li, Zhi; Wang, Wenjin; Zang, Xiaohuan; Wang, Chun; Wang, Zhi

2018-10-15

A hybrid composite featuring an iron-based metal-organic framework Material of Institute Lavoisier-88(Fe) and graphene oxide (MIL-88(Fe)/GO) was synthesized and used as the solid-phase microextraction (SPME) coating. The SPME fiber was prepared by covalent bonding of the MIL-88(Fe)/GO composite onto the stainless steel substrate. The fiber had a good durability and allowed >100 replicate extractions. The developed method, which combined the MIL-88(Fe)/GO coated fiber based SPME with gas chromatography-flame ionization detection (GC-FID), achieved low limits of detection (0.5-2.0 ng g -1 , S/N = 3) and good linearity (r 2  > 0.994) for the phthalic acid esters (PAEs) from various vegetable oil samples. The repeatability and fiber-to-fiber reproducibility were in the range of 4.0-9.1% and 5.7-11.4%, respectively. The method was successfully applied to the analysis of PAEs from vegetable oil samples with good recoveries (83.1-104.1%) and satisfactory precisions (RSDs < 10.5%), indicating that the MIL-88(Fe)/GO hybrid composite is a good coating material for the SPME of PAEs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrochemical preparation of polyaniline-polypyrrole solid-phase microextraction coating and its application in the GC determination of several esters.

PubMed

Zhao, Shasha; Wu, Mian; Zhao, Faqiong; Zeng, Baizhao

2013-12-15

A novel polyaniline-polypyrrole (PANI-PPY) composite film coated stainless steel wire was prepared by cyclic voltammetry. Firstly, PANI was electrodeposited on a stainless steel wire from a solution containing 0.1 M aniline and 1M HNO3, after the PANI coating was dried in air PPY was electrodeposited on it from a solution containing 0.1 M pyrrole and 0.1 M p-methylbenzene sulfonic acid. The resulting PANI-PPY fiber showed reticulate structure and had large specific surface area. When it was used for the headspace solid-phase microextraction of several esters (i.e. methyl anthranilate, ethyl-o-aminobenzoate, dimethyl phthalate, methyl laurate, and diethyl phthalate), followed by gas chromatographic determination, it presented higher extraction capability in comparison with PPY and PANI coatings. Under the optimized conditions, the linear ranges were 0.07-300 μg L(-1) and the detection limits were 0.05-0.38 μg L(-1) for different esters. The PANI-PPY fiber also showed high durability, after being used for about 160 times its extraction capacity only changed a little. The proposed method was successfully applied to the determination of these esters in real samples and the recoveries were 90-102%. © 2013 Elsevier B.V. All rights reserved.

Aggregation in complex triacylglycerol oils: coarse-grained models, nanophase separation, and predicted x-ray intensities

NASA Astrophysics Data System (ADS)

Quinn, Bonnie; Peyronel, Fernanda; Gordon, Tyler; Marangoni, Alejandro; Hanna, Charles B.; Pink, David A.

2014-11-01

Triacylglycerols (TAGs) are biologically important molecules which form crystalline nanoplatelets (CNPs) and, ultimately, fat crystal networks in edible oils. Characterizing the self-assembled hierarchies of these networks is important to understanding their functionality and oil binding capacity. We have modelled CNPs in multicomponent oils and studied their aggregation. The oil comprises (a) a liquid componentt, and (b) components which phase separately on a nano-scale (nano-phase separation) to coat the surfaces of the CNPs impenetrably, either isotropically or anisotropically, with either liquid-like coatings or crystallites, forming a coating of thickness Δ. We modelled three cases: (i) liquid-liquid nano-phase separation, (ii) solid-liquid nano-phase separation, with CNPs coated isotropically, and (iii) CNPs coated anisotropically. The models were applied to mixes of tristearin and triolein with fully hydrogenated canola oil, shea butter with high oleic sunflower oil, and cotton seed oil. We performed Monte Carlo simulations, computed structure functions and concluded: (1) three regimes arose: (a) thin coating regime, Δ \\lt 0.0701 u (b) transition regime, 0.0701 u≤slant Δ ≤slant 0.0916 u and (c) thick coating regime, Δ \\gt 0.0916 u . (arbitrary units, u) (2) The thin coating regime exhibits 1D TAGwoods, which aggregate, via DLCA/RLCA, into fractal structures which are uniformly distributed in space. (3) In the thick coating regime, for an isotropic coating, TAGwoods are not formed and coated CNPs will not aggregate but will be uniformly distributed in space. For anisotropic coating, TAGwoods can be formed and might form 1D strings but will not form DLCA/RLCA clusters. (4) The regimes are, approximately: thin coating, 0\\lt Δ \\lt 7.0 \\text{nm} transition regime, 7.0\\ltΔ \\lt 9.2 \\text{nm} and thick coating, Δ \\gt 9.2 \\text{nm} (5) The minimum minority TAG concentration required to undergo nano-phase separation is, approximately, 0.29% (thin coatings) and 0.94% (thick coatings). Minority components can have substantial effects upon aggregation for concentrations less than 1%.

Electron beam physical vapor deposition of YSZ electrolyte coatings for SOFCs

NASA Astrophysics Data System (ADS)

He, Xiaodong; Meng, Bin; Sun, Yue; Liu, Bochao; Li, Mingwei

2008-09-01

YSZ electrolyte coatings were prepared by electron beam physical vapor deposition (EB-PVD) at a high deposition rate of up to 1 μm/min. The YSZ coating consisted of a single cubic phase and no phase transformation occurred after annealing treatment at 1000 °C. A typical columnar structure was observed in this coating by SEM and feather-like characteristics appeared in every columnar grain. In columnar grain boundaries there were many micron-sized gaps and pores. In TEM image, many white lines were found, originating from the alignment of nanopores existing within feather-like columnar grains. The element distribution along the cross-section of the coating was homogeneous except Zr with a slight gradient. The coating exhibited a characteristic anisotropic behavior in electrical conductivity. In the direction perpendicular to coating surface the electrical conductivity was remarkably higher than that in the direction parallel to coating surface. This mainly attributed to the typical columnar structure for EB-PVD coating and the existence of many grain boundaries along the direction parallel to coating surface. For as-deposited coating, the gas permeability coefficient of 9.78 × 10 -5 cm 4 N -1 s -1 was obtained and this value was close to the critical value of YSZ electrolyte layer required for solid oxide fuel cell (SOFC) operation.

Electroplating of nanostructured polyaniline-polypyrrole composite coating in a stainless-steel tube for on-line in-tube solid phase microextraction.

PubMed

Asiabi, Hamid; Yamini, Yadollah; Seidi, Shahram; Esrafili, Ali; Rezaei, Fatemeh

2015-06-05

In this work, a novel and efficient on-line in-tube solid phase microextraction method followed by high performance liquid chromatography was developed for preconcentration and determination of trace amounts of parabens. A nanostructured polyaniline-polypyrrole composite was electrochemically deposited on the inner surface of a stainless steel tube and used as the extraction phase. Several important factors that influence the extraction efficiency, including type of solid-phase coating, extraction and desorption times, flow rates of the sample solution and eluent, pH, and ionic strength of the sample solution were investigated and optimized. Under the optimal conditions, the limits of detection were in the range of 0.02-0.04 μg L(-1). This method showed good linearity for parabens in the range of 0.07-50 μg L(-1), with coefficients of determination better than 0.998. The intra- and inter-assay precisions (RSD%, n=3) were in the range of 5.9-7.0% and 4.4-5.7% at three concentration levels of 2, 10, and 20 μg L(-1), respectively. The extraction recovery values for the spiked samples were in the acceptable range of 80.3-90.2%. The validated method was successfully applied for analysis of methyl-, ethyl-, and propyl parabens in some water, milk, and juice samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of new solid-phase microextraction fibers by sol-gel technology for the determination of organophosphorus pesticide multiresidues in food.

PubMed

Yu, Jianxin; Wu, Caiying; Xing, Jun

2004-05-21

Allyloxy bisbenzo 16-crown-5 trimethoxysilane was first used as precursor to prepare the sol-gel-derived bisbenzo crown ether/hydroxyl-terminated silicone oil (OH-TSO) SPME coating. The coating procedure involving sol solution composition and conditioning process was presented. Compared with commercial SPME stationary phases, the new coatings showed higher extraction efficiency and therefore could provide higher sensitivity for organphosphorous pesticides (OPs). Limits of detection (LODs) were in the range of 0.003-1.0 ng/g for these OPs in food samples (honey, juice, orange and pakchoi). The optimal extraction conditions of the new coatings to OPs in these samples were investigated by adjusting extraction time, salt addition, extraction temperature, and dilution ratios of samples with distilled water by using SPME coupled with gas chromatography (GC)-flame photometric detection (FPD). The method was applied to determine the concentrations of OPs in real samples.

Role of precursors and coating polymers in sol-gel chemistry toward enhanced selectivity and efficiency in solid phase microextraction.

PubMed

Bagheri, Habib; Piri-Moghadam, Hamed; Ahdi, Tayebeh

2012-09-12

To evaluate the selectivity and efficiency of solid phase microextraction (SPME) fiber coatings, synthesized by sol-gel technology, roles of precursors and coating polymers were extensively investigated. An on-line combination of capillary microextraction (CME) technique and high performance liquid chromatography (HPLC) was set up to perform the investigation. Ten different fiber coatings were synthesized in which five of them contained only the precursor and the rests were prepared using both the precursor and coating polymer. All the coatings were chemically bonded to the inner surface of copper tubes, intended to be used as the CME device and already functionalized by self-assembly monolayers of 3-(mercaptopropyl)trimethoxysilane (3MPTMOS). The selected precursors included tetramethoxysilane (TMOS), 3-(trimethoxysilyl)propylmethacrylate (TMSPMA), 3-(triethoxysilyl)-propylamine (TMSPA), 3MPTMOS, [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane (EPPTMOS) while poly(ethyleneglycol) (PEG) was chosen as the coating polymer. The effects of different precursors on the extraction efficiency and selectivity, was studied by selecting a list of compounds ranging from non-polar to polar ones, i.e. polycyclic aromatic hydrocarbon, herbicides, estrogens and triazines. The results from CME-HPLC analysis revealed that there is no significant difference between precursors, except TMOS, in which has the lowest extraction efficiency. Most of the selected precursors have rather similar interactions toward the selected analytes which include Van der Walls, dipole-dipole and hydrogen bond while TMOS has only dipole-dipole interaction and therefore the least efficiency. TMOS is silica but the other sorbents are organically modified silica (ORMOSIL). Our investigation revealed that it is rather impossible to prepare a selective coating using conventional sol-gel methodologies. The comparison study performed among the fiber coatings contained only a precursor and those synthesized by a precursor along with coating polymer proved that the extraction efficiency obtained for all coatings are the same. This is an indication that by selecting the appropriate precursor there is no need to use any coating polymer. In overall, a fiber coating in sol-gel process could be synthesize with no coating polymer which leads to faster, easier, cheaper and more controllable synthesis. Copyright © 2012 Elsevier B.V. All rights reserved.

Polydopamine-coated magnetic molecularly imprinted polymer for the selective solid-phase extraction of cinnamic acid, ferulic acid and caffeic acid from radix scrophulariae sample.

PubMed

Yin, Yuli; Yan, Liang; Zhang, Zhaohui; Wang, Jing; Luo, Ningjing

2016-04-01

We describe novel cinnamic acid polydopamine-coated magnetic imprinted polymers for the simultaneous selective extraction of cinnamic acid, ferulic acid and caffeic acid from radix scrophulariae sample. The novel magnetic imprinted polymers were synthesized by surface imprinting polymerization using magnetic multi-walled carbon nanotubes as the support material, cinnamic acid as the template and dopamine as the functional monomer. The magnetic imprinted polymers were characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The results revealed that the magnetic imprinted polymers had outstanding magnetic properties, high adsorption capacity, selectivity and fast kinetic binding toward cinnamic acid, ferulic acid and caffeic acid. Coupled with high-performance liquid chromatography, the extraction conditions of the magnetic imprinted polymers as a magnetic solid-phase extraction sorbent were investigated in detail. The proposed imprinted magnetic solid phase extraction procedure has been used for the purification and enrichment of cinnamic acid, ferulic acid and caffeic acid successfully from radix scrophulariae extraction sample with recoveries of 92.4-115.0% for cinnamic acid, 89.4-103.0% for ferulic acid and 86.6-96.0% for caffeic acid. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas chromatographic detection of some nitro explosive compounds in soil samples after solid-phase microextraction with carbon ceramic copper nanoparticle fibers.

PubMed

Farhadi, Khalil; Bochani, Shayesteh; Hatami, Mehdi; Molaei, Rahim; Pirkharrati, Hossein

2014-07-01

In this research, a new solid-phase microextraction fiber based on carbon ceramic composites with copper nanoparticles followed by gas chromatography with flame ionization detection was applied for the extraction and determination of some nitro explosive compounds in soil samples. The proposed method provides an overview of trends related to synthesis of solid-phase microextraction sorbents and their applications in preconcentration and determination of nitro explosives. The sorbents were prepared by mixing of copper nanoparticles with a ceramic composite produced by mixture of methyltrimethoxysilane, graphite, methanol, and hydrochloric acid. The prepared sorbents were coated on copper wires by dip-coating method. The prepared nanocomposites were evaluated statistically and provided better limits of detection than the pure carbon ceramic. The limit of detection of the proposed method was 0.6 μg/g with a linear response over the concentration range of 2-160 μg/g and square of correlation coefficient >0.992. The new proposed fiber has been demonstrated to be a suitable, inexpensive, and sensitive candidate for extraction of nitro explosive compounds in contaminated soil samples. The constructed fiber can be used more than 100 times without the need for surface generation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microstructure and Antiwear Property of Laser Cladding Ni-Co Duplex Coating on Copper.

PubMed

Wang, Yiyong; Liang, Zhipeng; Zhang, Junwei; Ning, Zhe; Jin, Hui

2016-07-28

Ni-Co duplex coatings were cladded onto Cu to improve the antiwear properties of Cu products. Prior to laser cladding, n-Al₂O₃/Ni layers were introduced as interlayers between laser cladding coatings and Cu substrates to improve the laser absorptivity of these substrates and ensure defect-free laser cladding coatings. The structure and morphology of the coatings were characterized by scanning electron microscopy and optical microscopy, and the phases of the coatings were analyzed by X-ray diffraction. Their hardness was measured using a microhardness tester. Experimental results showed that defect-free composite coatings were obtained and that the coatings were metallurgically bonded to the substrates. The surface of the Ni-Co duplex coatings comprised a Co-based solid solution, Cr₇C₃, (Fe,Ni) 23 C₆, and other strengthening phases. The microhardness and wear resistance of the duplex coatings were significantly improved compared with the Cu substrates. The average microhardness of the cladded coatings was 845.6 HV, which was approximately 8.2 times greater than that of the Cu substrates (102.6 HV). The volume loss of the Cu substrates was approximately 7.5 times greater than that of the Ni-Co duplex coatings after 60 min of sliding wear testing. The high hardness of and lack of defects in the Ni-Co duplex coatings reduced the plastic deformation and adhesive wear of the Cu substrates, resulting in improved wear properties.

Layer-by-layer fabrication of chemical-bonded graphene coating for solid-phase microextraction.

PubMed

Zhang, Suling; Du, Zhuo; Li, Gongke

2011-10-01

A new fabrication strategy of the graphene-coated solid-phase microextraction (SPME) fiber is developed. Graphite oxide was first used as starting coating material that covalently bonded to the fused-silica substrate using 3-aminopropyltriethoxysilane (APTES) as cross-linking agent and subsequently deoxidized by hydrazine to give the graphene coating in situ. The chemical bonding between graphene and the silica fiber improve its chemical stability, and the obtained fiber was stable enough for more than 150 replicate extraction cycles. The graphene coating was wrinkled and folded, like the morphology of the rough tree bark. Its performance is tested by headspace (HS) SPME of polycyclic aromatic hydrocarbons (PAHs) followed by GC/MS analysis. The results showed that the graphene-coated fiber exhibited higher enrichment factors (EFs) from 2-fold for naphthalene to 17-fold for B(b)FL as compared to the commercial polydimethylsioxane (PDMS) fiber, and the EFs increased with the number of condensed rings of PAHs. The strong adsorption affinity was believed to be mostly due to the dominant role of π-π stacking interaction and hydrophobic effect, according to the results of selectivity study for a variety of organic compounds including PAHs, the aromatic compounds with different substituent groups, and some aliphatic hydrocarbons. For PAHs analysis, the graphene-coated fiber showed good precision (<11%), low detection limits (1.52-2.72 ng/L), and wide linearity (5-500 ng/L) under the optimized conditions. The repeatability of fiber-to-fiber was 4.0-10.8%. The method was applied to simultaneous analysis of eight PAHs with satisfactory recoveries, which were 84-102% for water samples and 72-95% for soil samples, respectively.

Vanadium diffusion coating on HT-9 cladding for mitigating the fuel cladding chemical interactions

NASA Astrophysics Data System (ADS)

Lo, Wei-Yang; Yang, Yong

2014-08-01

Fuel cladding chemical interaction (FCCI) has been identified as one of the crucial issues for developing Ferritic/Martensitic (F/M) stainless steel claddings for metallic fuels in a fast reactor. The anticipated elevated temperature and high neutron flux can significantly aggravate the FCCI, in terms of formation of inter-diffusion and lower melting point eutectic phases. To mitigate the FCCI, vanadium carbide coating as a diffusion barrier was deposited on the HT-9 substrate using a pack cementation diffusion coating (PCDC) method, and the processing temperature was optimized down to 730 °C. A solid metallurgical bonding between the coating layer and substrate was achieved, and the coating is free from through depth cracks. The microstructural characterizations using SEM and TEM show a nanostructured grain structure. EDS/WDS and XRD analysis confirm the phase of coating layer as V2C. Diffusion couple tests at 660 °C for 100 h demonstrate that V2C layer with a thickness of less than 5 μm can effectively eliminate the inter-diffusion between the lanthanide cerium and HT-9 steel.

Thermal Spray Deposition, Phase Stability and Mechanical Properties of La2Zr2O7/LaAlO3 Coatings

NASA Astrophysics Data System (ADS)

Lozano-Mandujano, D.; Poblano-Salas, C. A.; Ruiz-Luna, H.; Esparza-Esparza, B.; Giraldo-Betancur, A. L.; Alvarado-Orozco, J. M.; Trápaga-Martínez, L. G.; Muñoz-Saldaña, J.

2017-08-01

This paper deals with the deposition of La2Zr2O7 (LZO) and LaAlO3 (LAO) mixtures by air plasma spray (APS). The raw material for thermal spray, single phase LZO and LAO in a 70:30 mol.% ratio mixture was prepared from commercial metallic oxides by high-energy ball milling (HEBM) and high-temperature solid-state reaction. The HEBM synthesis route, followed by a spray-drying process, successfully produced spherical agglomerates with adequate size distribution and powder-flow properties for feeding an APS system. The as-sprayed coating consisted mainly of a crystalline LZO matrix and partially crystalline LAO, which resulted from the high cooling rate experienced by the molten particles as they impact the substrate. The coatings were annealed at 1100 °C to promote recrystallization of the LAO phase. The reduced elastic modulus and hardness, measured by nanoindentation, increased from 124.1 to 174.7 GPa and from 11.3 to 14.4 GPa, respectively, after the annealing treatment. These values are higher than those reported for YSZ coatings; however, the fracture toughness ( K IC) of the annealed coating was only 1.04 MPa m0.5.

Effect of particle morphology of Ni on the mechanical behavior of AZ91E-Ni coated nano Al2O3 composites

NASA Astrophysics Data System (ADS)

Sameer Kumar, D.; Suman, K. N. S.; Poddar, Palash

2017-06-01

The properties of any composite always depend on the bonding between the matrix and reinforcement phases. One way of improving the wettability of reinforcement in a matrix is to apply a layer of coating on reinforcing particles. The present study aims at developing Ni coating on nano Al2O3 ceramic particles and dispersing them in AZ91E magnesium matrix material. The electroless plating method has been employed to coat the particles and semi solid stir casting technique was adopted to prepare the composites. Several weight fractions of dispersed phase are considered to analyze the behavior of the fabricated composites. Field emission scanning electron microscopy (FESEM) and x-ray diffraction analysis has been carried out to investigate the distribution of particles and phase characteristics of the proposed material. The physical and mechanical behavior of the material was examined through density measurements, hardness, elastic modulus, ductility and tensile strength calculations. The metal coating on reinforcement aids to promote metal-metal bonding interface reactions which result in improved properties of the composite. Tensile fractography was carried out under FESEM and presented.

High rate reactive sputtering of MoN(x) coatings

NASA Technical Reports Server (NTRS)

Rudnik, Paul J.; Graham, Michael E.; Sproul, William D.

1991-01-01

High rate reactive sputtering of MoN(x) films was performed using feedback control of the nitorgen partial pressure. Coatings were made at four different target powers: 2.5, 5.0, 7.5 and 10 kW. No hysteresis was observed in the nitrogen partial pressure vs. flow plot, as is typically seen for the Ti-N system. Four phases were determined by X-ray diffraction: molybdenum, Mo-N solid solution, Beta-Mo2N and gamma-Mo2N. The hardness of the coatings depended upon composition, substrate bias, and target power. The phases present in the hardest films differed depending upon deposition parameters. For example, the Beta-Mo2N phase was hardest (load 25 gf) at 5.0 kW with a value of 3200 kgf/sq mm, whereas the hardest coatings at 10 kW were the gamma-Mo2N phase (3000 kgf/sq mm). The deposition rate generally decreased with increasing nitrogen partial pressure, but there was a range of partial pressures where the rate was relatively constant. At a target power of 5.0 kW, for example, the deposition rates were 3300 A/min for a N2 partial pressure of 0.05 - 1.0 mTorr.

Sol-gel approach for fabrication of coated anodized titanium wire for solid-phase microextraction: highly efficient adsorbents for enrichment of trace polar analytes.

PubMed

Jia, Jing; Xu, Lili; Wang, Shuai; Wang, Licheng; Liu, Xia

2014-05-01

Nanotubular titania film was prepared in situ on titanium wire and was used as the fiber substrate for solid-phase microextraction (SPME) because of its high surface-to-volume ratio, easy preparation, and mechanical stability. Three different functional coatings, β-cyclodextrin (β-CD), β-cyclodextrin-co-poly(ethylenepropylene glycol) (β-CD/PEG), and polyethylene glycol (PEG)-based sorbents were chemically bonded to the nanostructured wire surface via sol-gel technology to further enhance the absorbing capability and extraction selectivity. Coupled to gas chromatography-flame ionic detection (GC-FID), the prepared SPME fibers were investigated using diverse compounds. The results indicated that the fibers showed good mechanical strength, excellent thermal stability, and wonderful capacity and selectivity to polar compounds, including polar aromatic compounds, alcohols, and ketones. Combining the superior hydrophilic property of a bonded functional molecule and the highly porous structure of a fiber coating, the prepared PEG-coated SPME fiber showed much higher adsorption affinity to ephedrine and methylephedrine than β-CD and β-CD/PEG fibers. The as-established PEG-coated SPME-GC analytical method provided excellent sensitivity (LODs, 0.004 and 0.001 ng mL(-1) for ephedrine and methylephedrine, respectively) and better linear range (0.01-2 000 μg L(-1)). In addition, it has surprising repeatability and reproducibility. Finally, the present approach was used to analyze ephedrine and methylephedrine from real urine samples, and reliable results were obtained.

Development of coatings for automated 96-blade solid phase microextraction-liquid chromatography-tandem mass spectrometry system, capable of extracting a wide polarity range of analytes from biological fluids.

PubMed

Mirnaghi, Fatemeh S; Pawliszyn, Janusz

2012-10-26

This work presents the development and evaluation of biocompatible polyacrylonitrile-polystyrene-divinylbenzene (PAN-PS-DVB) and polyacrylonitrile-phenylboronic acid (PAN-PBA) coatings for automated 96-blades (thin-film) solid phase microextraction (SPME) system, using high performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS). The SPME condition was optimized for 60 min equilibrium extraction and 40 min desorption for PAN-PS-DVB, and 120 min equilibrium extraction and 60 min desorption for PAN-PBA for parallel sample preparation of up to 96 samples. The thin film geometry of the SPME blades provided good extraction efficiency due to the larger surface area of the coating, and simultaneous sample preparation provided fast and accurate analysis. The PAN-PS-DVB and PAN-PBA 96-blade SPME coatings were evaluated for extraction of analytes in a wide range of polarity (log P=2.8 to -3.7), and they demonstrated efficient extraction recovery (3.5-98.9% for PAN-PS-DVB and 4.0-74.1% for PAN-PBA) for both polar and non-polar groups of compounds. Reusability, reproducibility, and reliability of the system were evaluated. The results demonstrated that both coatings presented chemical and mechanical stability and long-lasting extraction efficiency for more than 100 usages in phosphate-buffered saline (PBS) and human plasma. Copyright © 2012 Elsevier B.V. All rights reserved.

Crosslinked polymeric ionic liquids as solid-phase microextraction sorbent coatings for high performance liquid chromatography.

PubMed

Yu, Honglian; Merib, Josias; Anderson, Jared L

2016-03-18

Neat crosslinked polymeric ionic liquid (PIL) sorbent coatings for solid-phase microextraction (SPME) compatible with high-performance liquid chromatography (HPLC) are reported for the first time. Six structurally different PILs were crosslinked to nitinol supports and applied for the determination of select pharmaceutical drugs, phenolics, and insecticides. Sampling conditions including sample solution pH, extraction time, desorption solvent, desorption time, and desorption solvent volume were optimized using design of experiment (DOE). The developed PIL sorbent coatings were stable when performing extractions under acidic pH and remained intact in various organic desorption solvents (i.e., methanol, acetonitrile, acetone). The PIL-based sorbent coating polymerized from the IL monomer 1-vinyl-3-(10-hydroxydecyl) imidazolium chloride [VC10OHIM][Cl] and IL crosslinker 1,12-di(3-vinylbenzylimidazolium) dodecane dichloride [(VBIM)2C12] 2[Cl] exhibited superior extraction performance compared to the other studied PILs. The extraction efficiency of pharmaceutical drugs and phenolics increased when the film thickness of the PIL-based sorbent coating was increased while many insecticides were largely unaffected. Satisfactory analytical performance was obtained with limits of detection (LODs) ranging from 0.2 to 2 μg L(-1) for the target analytes. The accuracy of the analytical method was examined by studying the relative recovery of analytes in real water samples, including tap water and lake water, with recoveries varying from 50.2% to 115.9% and from 48.8% to 116.6%, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Moisture stable Ni-Zn MOF/g-C3N4 nanoflowers: A highly efficient adsorbent for solid-phase microextraction of PAHs.

PubMed

Zhang, Ning; Huang, Chuanhui; Tong, Ping; Feng, Zunmei; Wu, Xiaoping; Zhang, Lan

2018-06-29

Volatile polycyclic aromatic hydrocarbons (PAHs) in water and soil are associated with status in the human body. Development of simple, efficient detection method is challenging due to the coating could be attacked by the abundance of water in the direct-immersion solid-phase microextraction. The stability of coating is essential to the analysis results. In this paper, a stable Ni-Zn MOF/g-C 3 N 4 (MG NFs) nanoflowers with cavity traps structure was firstly reported and acted as solid-phase microextraction (SPME) adsorbent for PAHs. Markedly enhanced moisture and acid stability of the MG NFs was obtained through the doping the hydrophobic graphitic carbon nitride (g-C 3 N 4 ) and metal ions into metal organic frameworks (MOFs). The aperture environment and ambient environment of MG NFs were changed by the doping of the Ni and the g-C 3 N 4, respectively. The moisture and acid stability of MG NFs were prominently increased under the dual protection. Compared to commonly used commercial coatings, the MG NFs own large surface area, unique nanoflowers structure and numerous open metal sites on the nanosheets, which demonstrated significant extraction superiority for PAHs. The MG NFs coated fiber was used for the SPME preconcentration of PAHs and couped with GC-MS for detecting PAHs. It presented low detection limits (0.1-3.0 ng L -1 ), wide linearity (0.3-5000.0 ng L -1 ) and good linearity (the correlation coefficient >0.9951). The inter-day and intra-day relative standard deviation (RSD) (n = 3) for three replicate extractions using one fiber was 3.8%-9.1%, and 3.5%-9.2%, respectively. The fiber-to-fiber reproducibility (n = 3) was 4.2-11.8%. The coupling method was successfully applied in the analysis of real water and soil samples with satisfactory recoveries of 82.9-109.2%, 84.2-106.4%, and the corresponding RSDs were 2.4-11.3%, 3.6-10.8%, respectively. The results indicated the effectiveness of NG NFs coated fiber in further practical application. Copyright © 2018 Elsevier B.V. All rights reserved.

Criteria for the selection of a solid phase to be used in immunoassays.

PubMed

Delagneau, J F; Masseyeff, R

1990-01-01

Heterogeneous immunoassays are very sensitive and only limited in terms of performance by non specific binding. They require separation of free from bound fractions and concomitant use of a solid phase coated with an immunoreactive component (i.e. immunosorbent). The improvement of these key immunosorbents is crucial and involves a great deal of expertise and capabilities. Specifications differ according to procedure (e.g. capture or competitive assay). Each routinely used solid phase, such as polystyrene wells, porous membrane or dispersible microbeads, presents specific performance characteristics, advantages, and drawbacks. Among the tasks to be implemented are optimization of the spatial orientation of immunological reagents, selection of the surface neutral hydrophilic support, acceleration of reactions by increasing the reactive surface area of the supports, streamlining and simplification of procedural steps. These various aspects are abundantly described and emphasized here.

Chromium Vaporization Reduction by Nickel Coatings For SOEC Interconnect Materials

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

Michael V. Glazoff; Sergey N. Rashkeev; J. Stephen Herring

2014-09-01

The vaporization of Cr-rich volatile species from interconnect materials is a major source of degradation that limits the lifetime of planar solid oxide devices systems with metallic interconnects, including Solid Oxide Electrolysis Cells, or SOECs. Some metallic coatings (Ni, Co, and Cu) significantly reduce the Cr release from interconnects and slow down the oxide scale growth on the steel substrate. To shed additional light upon the mechanisms of such protection and find a suitable coating material for ferritic stainless steel materials, we used a combination of first-principles calculations, thermodynamics, and diffusion modeling to investigate which factors determine the quality ofmore » the Ni metallic coating at stainless steel interconnector. We found that the Cr migration in Ni coating is determined by a delicate combination of the nickel oxidation, Cr diffusion, and phase transformation processes. Although the formation of Cr2O3 oxide is more exothermic than that of NiO, the kinetic rate of the chromia formation in the coating layer and its surface is significantly reduced by the low mobility of Cr in nickel oxide and in NiCr2O4 spinel. These results are in a good agreement with diffusion modeling for Cr diffusion through Ni coating layer on the ferritic 441 steel substrate.« less

Poly(ionic liquids)-coated stainless-steel wires packed into a polyether ether ketone tube for in-tube solid-phase microextraction.

PubMed

Feng, Juanjuan; Wang, Xiuqin; Tian, Yu; Luo, Chuannan; Sun, Min

2017-12-01

An in-tube solid-phase microextraction device was developed by packing poly(ionic liquids)-coated stainless-steel wires into a polyether ether ketone tube. An anion-exchange process was performed to enhance the extraction performance. Surface properties of poly(ionic liquids)-coated stainless-steel wires were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. The extraction device was connected to high-performance liquid chromatography equipment to build an online enrichment and analysis system. Ten polycyclic aromatic hydrocarbons were used as model analytes, and important conditions including extraction time and desorption time were optimized. The enrichment factors from 268 to 2497, linear range of 0.03-20 μg/L, detection limits of 0.010-0.020 μg/L, extraction and preparation repeatability with relative standard deviation less than 1.8 and 19%, respectively were given by the established online analysis method. It has been used to detect polycyclic aromatic hydrocarbons in environmental samples, with the relative recovery (5, 10 μg/L) in the range of 85.1-118.9%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and application of the sol-gel-derived acrylate/silicone co-polymer coatings for headspace solid-phase microextraction of 2-chloroethyl ethyl sulfide in soil.

PubMed

Liu, Mingming; Zeng, Zhaorui; Fang, Huaifang

2005-05-27

Three types of novel acrylate/silicone co-polymer coatings, including co-poly(methyl acrylate/hydroxy-terminated silicone oil) (MA/OH-TSO), co-poly(methyl methacrylate/OH-TSO) (MMA/OH-TSO) and co-poly(butyl methacrylate/OH-TSO) (BMA/OH-TSO), were prepared for the first time by sol-gel method and cross-linking technology and subsequently applied to headspace solid-phase microextraction (HS-SPME) of 2-chloroethyl ethyl sulfide (CEES), a surrogate of mustard, in soil. The underlying mechanisms of the coating process were discussed and confirmed by IR spectra. The selectivity of the three types of sol-gel-derived acrylate/silicone coated fibers was studied, and the BMA/OH-TSO coated fibers exhibited the highest extraction ability to CEES. The concentration of BMA and OH-TSO in sol solution was optimized, and the BMA/OH-TSO (3:1)-coated fibers possessed the highest extraction efficiency. Compared with commercially available polyacrylate (PA) fiber, the sol-gel-derived BMA/OH-TSO (3:1) fibers showed much higher extraction efficiency to CEES. Therefore, the BMA/OH-TSO (3:1)-coated fibers were chosen for the analysis of CEES in soil matrix. The reproducibility of coating preparation was satisfactory, with the RSD 2.39% within batch and 3.52% between batches, respectively. The coatings proved to be quite stable at high temperature (to 350 degrees C) and in different solvents (organic or inorganic), thus their lifetimes (to 150 times) are longer than conventional fibers. Extraction parameters, such as the volume of water added to the soil, extraction temperature and time, and the ionic strength were optimized. The linearity was from 0.1 to 10 microg/g, the limit of detection (LOD) was 2.7 ng/g, and the RSD was 2.19%. The recovery of CEES was 88.06% in agriculture soil, 92.61% in red clay, and 101.95% in sandy soil, respectively.

Failure Mechanism of a Stellite Coating on Heat-Resistant Steel

NASA Astrophysics Data System (ADS)

Wang, Dong; Zhao, Haixing; Wang, Huang; Li, Yuyan; Liu, Xia; He, Guo

2017-09-01

The Stellite 21 coating on the heat-resistant steel X12CrMoWVNbN10-1-1 (so-called COSTE) used in a steam turbine valve was found to be fatigue broken after service at around 873 K (600 °C) for about 8 years. In order to investigate the failure mechanism, a fresh Stellite 21 coating was also prepared on the same COSTE steel substrate by using the similar deposition parameters for comparison. It was found that the Stellite 21 coating was significantly diluted by the steel, resulting in a thin Fe-rich layer in the coating close to the fusion line. Such high Fe concentration together with the incessant Fe diffusion from the steel substrate to the coating during the service condition (about 873 K (600 °C) for long time) induced the eutectoid decomposition of the fcc α-Co(Fe,Cr,Mo) solid solution, forming an irregular eutectoid microstructure that was composed of the primitive cubic α'-FeCo(Cr,Mo) phase and the tetragonal σ-CrCo(Fe,Mo) phase. The brittle nature of such α'/ σ eutectoid microstructure contributed to the fatigue fracture of the Stellite 21 coating, resulting in an intergranular rupture mode.

On the kinetics of pack aluminization

NASA Technical Reports Server (NTRS)

Gupta, B. K.; Sarkhel, A. K.; Seigle, L. L.

1975-01-01

A theory of pack aluminization has been formulated by combining gaseous and solid-state diffusion rates. This theory relates the surface composition of the coating and therefore, in principle, the phase morphology and the growth rate of the coating, to pack operating parameters such as pack aluminum density, type of activator, temperature and others. Experimental data on the aluminization of unalloyed nickel in pure aluminum packs obtained to date are in good agreement with the predictions of the theory.

Electrochemical fabrication of a novel polycarbazole coating for the headspace solid-phase microextraction and GC determination of some chlorobenzenes.

PubMed

Wang, Meng; Zhao, Fa-Qiong; Zeng, Bai-Zhao

2014-04-01

A novel polycarbazole coating was prepared by cyclic voltammetry on a platinum wire. The solution for electropolymerization contained N,N-dimethylformamide, propylene carbonate (v/v = 1:9), 0.10 M carbazole and 0.10 M tetrabutylammonium perchlorate; the cyclic scan potential range was 0.8-2.0 V (versus Ag/AgCl). The resulting polycarbazole coating showed a porous structure and had a large specific surface area. When it was used for the headspace solid-phase microextraction of chlorobenzenes (i.e. chlorobenzene, 2-chlorotoluene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,2,4-trichlorobenzene) followed by GC analysis, it presented excellent analytical performance. Under the optimized conditions the linear ranges were 0.25-250 μg/L with correlation coefficients >0.985, and the low detection limits were 15-61 ng/L (S/N = 3) for different chlorobenzenes. The RSDs were 2.4-4.9% for five successive measurements with a single fiber, and for fiber-to-fiber they were 6.3-13.1% (n = 5). Furthermore, the polycarbazole coating displayed good thermal stability (>350°C) and durability (more than 250 times). The proposed method was successfully applied to the extraction and determination of chlorobenzenes in waste water and lake water, and the recoveries for standards added were 86-114% for different analytes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Elevated Temperature Solid Particle Erosion Performance of Plasma-Sprayed Co-based Composite Coatings with Additions of Al2O3 and CeO2

NASA Astrophysics Data System (ADS)

Nithin, H. S.; Desai, Vijay; Ramesh, M. R.

2017-11-01

In this paper, investigation into solid particle erosion behavior of atmospheric plasma-sprayed composite coating of CoCrAlY reinforced with Al2O3 and CeO2 oxides on Superni 76 at elevated temperature of 600 °C is presented. Alumina particles are used as erodent at two impact angles of 30° and 90°. The microstructure, porosity, hardness, toughness and adhesion properties of the as-sprayed coatings are studied. The effects of temperature and phase transformation in the coatings during erosion process are analyzed using XRD and EDS techniques. Optical profilometer is used for accurate elucidation of erosion volume loss. CoCrAlY/CeO2 coating showed better erosion resistance with a volume loss of about 50% of what was observed in case of CoCrAlY/Al2O3/YSZ coating. Lower erosion loss is observed at 90° as compared to 30° impact angle. The erosion mechanism evaluated using SEM micrograph revealed that the coatings experienced ductile fracture exhibiting severe deformation with unusual oxide cracks. Reinforced metal oxides provide shielding effect for erodent impact, enabling better erosion resistance. The oxidation of the coating due to high-temperature exposure reforms erosion process into oxidation-modified erosion process.

40 CFR 63.5749 - How do I calculate the organic HAP content of aluminum wipedown solvents?

Code of Federal Regulations, 2013 CFR

2013-07-01

... solvents, kilograms of HAP per liter of total coating solids from aluminum primers, top coats, and clear... = volume of aluminum primer, top coat, or clear coat i used in the past 12 months, liters. Solidsi= solids content aluminum primer, top coat, or clear coat i, liter solids per liter of coating. (b) Compliance is...

40 CFR 63.5749 - How do I calculate the organic HAP content of aluminum wipedown solvents?

Code of Federal Regulations, 2012 CFR

2012-07-01

... solvents, kilograms of HAP per liter of total coating solids from aluminum primers, top coats, and clear... = volume of aluminum primer, top coat, or clear coat i used in the past 12 months, liters. Solidsi= solids content aluminum primer, top coat, or clear coat i, liter solids per liter of coating. (b) Compliance is...

40 CFR 63.5749 - How do I calculate the organic HAP content of aluminum wipedown solvents?

Code of Federal Regulations, 2014 CFR

2014-07-01

... solvents, kilograms of HAP per liter of total coating solids from aluminum primers, top coats, and clear... = volume of aluminum primer, top coat, or clear coat i used in the past 12 months, liters. Solidsi = solids content aluminum primer, top coat, or clear coat i, liter solids per liter of coating. (b) Compliance is...

Microstructure and Antiwear Property of Laser Cladding Ni–Co Duplex Coating on Copper

PubMed Central

Wang, Yiyong; Liang, Zhipeng; Zhang, Junwei; Ning, Zhe; Jin, Hui

2016-01-01

Ni–Co duplex coatings were cladded onto Cu to improve the antiwear properties of Cu products. Prior to laser cladding, n-Al2O3/Ni layers were introduced as interlayers between laser cladding coatings and Cu substrates to improve the laser absorptivity of these substrates and ensure defect-free laser cladding coatings. The structure and morphology of the coatings were characterized by scanning electron microscopy and optical microscopy, and the phases of the coatings were analyzed by X-ray diffraction. Their hardness was measured using a microhardness tester. Experimental results showed that defect-free composite coatings were obtained and that the coatings were metallurgically bonded to the substrates. The surface of the Ni–Co duplex coatings comprised a Co-based solid solution, Cr7C3, (Fe,Ni)23C6, and other strengthening phases. The microhardness and wear resistance of the duplex coatings were significantly improved compared with the Cu substrates. The average microhardness of the cladded coatings was 845.6 HV, which was approximately 8.2 times greater than that of the Cu substrates (102.6 HV). The volume loss of the Cu substrates was approximately 7.5 times greater than that of the Ni–Co duplex coatings after 60 min of sliding wear testing. The high hardness of and lack of defects in the Ni–Co duplex coatings reduced the plastic deformation and adhesive wear of the Cu substrates, resulting in improved wear properties. PMID:28773755

Solid-phase microextraction of methadone in urine samples by electrochemically co-deposited sol-gel/Cu nanocomposite fiber.

PubMed

Mohammadiazar, Sirwan; Hasanli, Fateme; Maham, Mehdi; Payami Samarin, Somayeh

2017-08-01

Electrochemically co-deposited sol-gel/Cu nanocomposites have been introduced as a novel, simple and single-step technique for preparation of solid-phase microextraction (SPME) coating to extract methadone (MDN) (a synthetic opioid) in urine samples. The porous surface structure of the sol-gel/Cu nanocomposite coating was revealed by scanning electron microscopy. Direct immersion SPME followed by HPLC-UV determination was employed. The factors influencing the SPME procedure, such as the salt content, desorption solvent type, pH and equilibration time, were optimized. The best conditions were obtained with no salt content, acetonitrile as desorption solvent type, pH 9 and 10 min equilibration time. The calibration graphs for urine samples showed good linearity. The detection limit was about 0.2 ng mL -1 . Also, the novel method for preparation of nanocomposite fiber was compared with previously reported techniques for MDN determination. The results show that the novel nanocomposite fiber has relatively high extraction efficiency. Copyright © 2016 John Wiley & Sons, Ltd.

Complement activating properties of complexes containing rheumatoid factor in synovial fluids and sera from patients with rheumatoid arthritis.

PubMed Central

Elson, C J; Carter, S D; Cottrell, B J; Scott, D G; Bacon, P A; Wallington, T B

1985-01-01

The relationship between complexes containing rheumatoid factor and complexes activating complement was examined in synovial fluids and sera from patients with rheumatoid arthritis (RA). In each case this was performed by quantifying the amount of rheumatoid factor bound by solid phase Fab'2 anti-C3 and/or solid phase conglutinin. Both anti-C3 coated and conglutinin coated microtitre plates bound high levels of complexes containing rheumatoid factor from sera of RA patients with vasculitis. Unexpectedly, these complexes were detected in synovial fluids from only a minority of RA patients with synovitis. However, RA synovial fluids did contain other complexes as shown by the presence of complement consuming activity, C1q binding material and immunoglobulin attaching to conglutinin. It is considered that in RA synovial fluids the complexes containing RF and those activating complement are not necessarily the same whilst in vasculitic sera the complexes containing rheumatoid factor also activate complement. PMID:3978872

A solid-phase assay for studying direct binding of progranulin to TNFR and progranulin antagonism of TNF/TNFR interactions.

PubMed

Tian, Qingyun; Zhao, Shuai; Liu, Chuanju

2014-01-01

The discovery that TNF receptors (TNFR) serve as the binding receptors for progranulin (PGRN) reveals the significant role of PGRN in inflammatory and autoimmune diseases, including inflammatory arthritis. Herein we describe a simple, antibody-free analytical assay, i.e., a biotin-based solid-phase binding assay, to examine the direct interaction of PGRN/TNFR and the PGRN inhibition of TNF/TNFR interactions. Briefly, a 96-well high-binding microplate is first coated with the first protein (protein A), and after blocking, the coated microplate is incubated with the biotin-labeled second protein (protein B) in the absence or presence of the third protein (protein C). Finally the streptavidin conjugated with a detecting enzyme is added, followed by a signal measurement. Also discussed in this chapter are the advantages of the strategy, key elements to obtain reliable results, and discrepancies among various PGRN proteins in view of the binding activity with TNFR.

Automated direct-immersion solid-phase microextraction using crosslinked polymeric ionic liquid sorbent coatings for the determination of water pollutants by gas chromatography.

PubMed

Cordero-Vaca, María; Trujillo-Rodríguez, María J; Zhang, Cheng; Pino, Verónica; Anderson, Jared L; Afonso, Ana M

2015-06-01

Four different crosslinked polymeric ionic liquid (PIL)-based sorbent coatings were evaluated in an automated direct-immersion solid-phase microextraction method (automated DI-SPME) in combination with gas chromatography (GC). The crosslinked PIL coatings were based on vinyl-alkylimidazolium- (ViCnIm-) or vinylbenzyl-alkylimidazolium- (ViBzCnIm-) IL monomers, and di-(vinylimidazolium)dodecane ((ViIm)2C12-) or di-(vinylbenzylimidazolium)dodecane ((ViBzIm)2C12-) dicationic IL crosslinkers. In addition, a PIL-based hybrid coating containing multi-walled carbon nanotubes (MWCNTs) was also studied. The studied PIL coatings were covalently attached to derivatized nitinol wires and mounted onto the Supelco assembly to ensure automation when acting as SPME coatings. Their behavior was evaluated in the determination of a group of water pollutants, after proper optimization. A comparison was carried out with three common commercial SPME fibers. It was observed that those PILs containing a benzyl group in their structures, either in the IL monomer and crosslinker (PIL-1-1) or only in the crosslinker (PIL-0-1), were the most efficient sorbents for the selected analytes. The validation of the overall automated DI-SPME-GC-flame ionization detector (FID) method gave limits of detection down to 135 μg · L(-1) for p-cresol when using the PIL-1-1 and down to 270 μg · L(-1) when using the PIL-0-1; despite their coating thickness: ~2 and ~5 μm, respectively. Average relative recoveries with waters were of 85 ± 14 % and 87 ± 15 % for PIL-1-1 and PIL-0-1, respectively. Precision values as relative standard deviation were always lower than 4.9 and 7.6 % (spiked level between 10 and 750 μg · L(-1), as intra-day precision). Graphical Abstract Automated DI-SPME-GC-FID using crosslinked-PILs sorbent coatings for the determination of waterpollutants.

Polymer coating behavior of Rayleigh-SAW resonators with gold electrode structure for gas sensor applications.

PubMed

Avramov, Ivan D; Länge, Kerstin; Rupp, Swen; Rapp, Bastian; Rapp, Michael

2007-01-01

Results from systematic polymer coating experiments on surface acoustic wave (SAW) resonators and coupled resonator filters (CRF) on ST-cut quartz with a corrosion-proof electrode structure entirely made of gold (Au) are presented and compared with data from similar SAW devices using aluminium (Al) electrodes. The recently developed Au devices are intended to replace their earlier Al counterparts in sensor systems operating in highly reactive chemical gas environments. Solid parylene C and soft poly[chlorotrifluoroethylene-co-vinylidene fluoride] (PCFV) polymer films are deposited under identical conditions onto the surface of Al and Au devices. The electrical performance of the Parylene C coated devices is monitored online during film deposition. The PCVF coated devices are evaluated after film deposition. The experimental data show that the Au devices can stand up to 40% thicker solid films for the same amount of loss increase than the Al devices and retain better resonance and phase characteristics. The frequency sensitivities of Au and Al devices to parylene C deposition are nearly identical. After coating with soft PCFV sensing film, the Au devices provide up to two times higher gas sensitivity when probed with cooling agent, octane, or tetrachloroethylene.

Concentration of organic compounds in natural waters with solid-phase dispersion based on advesicle modified silica prior to liquid chromatography.

PubMed

Parisis, Nikolaos A; Giokas, Dimosthenis L; Vlessidis, Athanasios G; Evmiridis, Nicholaos P

2005-12-02

The ability of vesicle-coated silica to aid the extraction of organic compounds from water prior to liquid chromatographic analysis is presented for the first time. The method is based on the formation of silica supported cationic multi-lamellar vesicles of gemini surfactants inherently ensuring the presence of hydrophilic and hydrophobic sites for the partitioning of analytes bearing different properties. Method development is illustrated by studying the adsolubilization of UV absorbing chemicals from swimming pool water. Due to the requirement for external energy input (intense shearing) a method based on solid-phase dispersion (SPD) was applied producing better results than off-line solid-phase extraction (SPE). Meticulous investigation of the experimental parameters was conducted in order to elucidate the mechanisms behind the proposed extraction pattern. Analyte recoveries were quantitative under the optimum experimental conditions offering recoveries higher than 96% with RSD values below 5%.

A rapid space-resolved solid-phase microextraction method as a powerful tool to determine contaminants in wine based on their volatility.

PubMed

Liu, Min; Peng, Qing-Qing; Chen, Yu-Feng; Tang, Qian; Feng, Qing

2015-06-01

A novel space-resolved solid phase microextraction (SR-SPME) technique was developed to facilitate simultaneously analyte monitoring within heterogeneous samples. Graphene (G) and graphene oxide (GO) were coated separately to the segmented fibers which were successfully used for the solid-phase microextraction of two contaminants with dramatically different volatility: 2,4,6-trichloroanisole (TCA) and dibutyl phthalate (DBP). The space-resolved fiber showed good precision (5.4%, 6.8%), low detection limits (0.3ng/L, 0.3ng/L), and wide linearity (1.0-250.0ng/L, 1.0-250.0ng/L) under the optimized conditions for TCA and DBP, respectively. The method was applied to simultaneous analysis of the two contaminates with satisfactory recoveries, which were 96.96% and 98.20% for wine samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of Mo on Microstructures and Wear Properties of In Situ Synthesized Ti(C,N)/Ni-Based Composite Coatings by Laser Cladding.

PubMed

Wu, Fan; Chen, Tao; Wang, Haojun; Liu, Defu

2017-09-06

Using Ni60 alloy, C, TiN and Mo mixed powders as the precursor materials, in situ synthesized Ti(C,N) particles reinforcing Ni-based composite coatings are produced on Ti6Al4V alloys by laser cladding. Phase constituents, microstructures and wear properties of the composite coatings with 0 wt % Mo, 4 wt % Mo and 8 wt % Mo additions are studied comparatively. Results indicate that Ti(C,N) is formed by the in situ metallurgical reaction, the (Ti,Mo)(C,N) rim phase surrounding the Ti(C,N) ceramic particle is synthesized with the addition of Mo, and the increase of Mo content is beneficial to improve the wear properties of the cladding coatings. Because of the effect of Mo, the grains are remarkably refined and a unique core-rim structure that is uniformly dispersed in the matrix appears; meanwhile, the composite coatings with Mo addition exhibit high hardness and excellent wear resistance due to the comprehensive action of dispersion strengthening, fine grain strengthening and solid solution strengthening.

Effect of Mo on Microstructures and Wear Properties of In Situ Synthesized Ti(C,N)/Ni-Based Composite Coatings by Laser Cladding

PubMed Central

Chen, Tao; Wang, Haojun

2017-01-01

Using Ni60 alloy, C, TiN and Mo mixed powders as the precursor materials, in situ synthesized Ti(C,N) particles reinforcing Ni-based composite coatings are produced on Ti6Al4V alloys by laser cladding. Phase constituents, microstructures and wear properties of the composite coatings with 0 wt % Mo, 4 wt % Mo and 8 wt % Mo additions are studied comparatively. Results indicate that Ti(C,N) is formed by the in situ metallurgical reaction, the (Ti,Mo)(C,N) rim phase surrounding the Ti(C,N) ceramic particle is synthesized with the addition of Mo, and the increase of Mo content is beneficial to improve the wear properties of the cladding coatings. Because of the effect of Mo, the grains are remarkably refined and a unique core-rim structure that is uniformly dispersed in the matrix appears; meanwhile, the composite coatings with Mo addition exhibit high hardness and excellent wear resistance due to the comprehensive action of dispersion strengthening, fine grain strengthening and solid solution strengthening. PMID:28878190

The Effects of Substrate Material and Thermal Processing Atmosphere on the Strength of PS304: A High Temperature Solid Lubricant Coating

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher

2002-01-01

PS304, a plasma spray deposited solid lubricant coating developed for high temperature sliding contacts was deposited on nine different substrate metals, heat treated at 650C in either air or argon and subsequently tested for strength using a commercially available pull-off adhesion test. Some samples were examined metallographically to help elucidate and explain the results. As deposited coatings exhibit pull-off strengths typically between 16 and 20 MPa with failure occuring (cohesively) within the coating. Heat treatment in argon at 650 C results in a slight increase in coating (cohesive) strength of about 30 percent to 21 to 27 MPa. Heat treatment in air at 650 C results in a dramatic increase in strength to over 30 MPa, exceeding the strength of the epoxy used in the pull test. Cross section metallographic analyses show that no microstructural coating changes occur following the argon heat treatments, however, exposure to air at 650C gives rise to the formation of a second chromium-rich phase precipitate within the PS304 NiCr constituent which provides a strengthening effect and a slight (approximately 5 percent) coating thickness increase. Subsequent heat treatments do not result in any further coating changes. Based upon these studies, PS304 is a suitable coating for use on a wide variety of high temperature substrates and must be heat treated following deposition to enhance strength and ensure dimensional stability.

Delayed release film coating applications on oral solid dosage forms of proton pump inhibitors: case studies.

PubMed

Missaghi, Shahrzad; Young, Cara; Fegely, Kurt; Rajabi-Siahboomi, Ali R

2010-02-01

Formulation of proton pump inhibitors (PPIs) into oral solid dosage forms is challenging because the drug molecules are acid-labile. The aim of this study is to evaluate different formulation strategies (monolithic and multiparticulates) for three PPI drugs, that is, rabeprazole sodium, lansoprazole, and esomeprazole magnesium, using delayed release film coating applications. The core tablets of rabeprazole sodium were prepared using organic wet granulation method. Multiparticulates of lansoprazole and esomeprazole magnesium were prepared through drug layering of sugar spheres, using powder layering and suspension layering methods, respectively. Tablets and drug-layered multiparticulates were seal-coated, followed by delayed release film coating application, using Acryl-EZE(R), aqueous acrylic enteric system. Multiparticulates were then filled into capsules. The final dosage forms were evaluated for physical properties, as well as in vitro dissolution testing in both compendial acid phase, 0.1N HCl (pH 1.2), and intermediate pH, acetate buffer (pH 4.5), followed by phosphate buffer, pH 6.8. The stability of the delayed release dosage forms was evaluated upon storage in accelerated conditions [40 degrees C/75% relative humidity] for 3 months. All dosage forms demonstrated excellent enteric protection in the acid phase, followed by rapid release in their respective buffer media. Moreover, the delayed release dosage forms remained stable under accelerated stability conditions for 3 months. Results showed that Acryl-EZE enteric coating systems provide excellent performance in both media (0.1N HCl and acetate buffer pH 4.5) for monolithic and multiparticulate dosage forms.

Mobility of arsenic in a Bangladesh aquifer: Inferences from geochemical profiles, leaching data, and mineralogical characterization

NASA Astrophysics Data System (ADS)

Swartz, Christopher H.; Blute, Nicole Keon; Badruzzman, Borhan; Ali, Ashraf; Brabander, Daniel; Jay, Jenny; Besancon, James; Islam, Shafiqul; Hemond, Harold F.; Harvey, Charles F.

2004-11-01

Aquifer geochemistry was characterized at a field site in the Munshiganj district of Bangladesh where the groundwater is severely contaminated by As. Vertical profiles of aqueous and solid phase parameters were measured in a sandy deep aquifer (depth >150 m) below a thick confining clay (119 to 150 m), a sandy upper aquifer (3.5 to 119 m) above this confining layer, and a surficial clay layer (<3.5 m). In the deep aquifer and near the top of the upper aquifer, aqueous As levels are low (<10 μg/L), but aqueous As approaches a maximum of 640 μg/L at a depth of 30 to 40 m and falls to 58 μg/L near the base (107 m) of the upper aquifer. In contrast, solid phase As concentrations are uniformly low, rarely exceeding 2 μg/g in the two sandy aquifers and never exceeding 10 μg/g in the clay layers. Solid phase As is also similarly distributed among a variety of reservoirs in the deep and upper aquifer, including adsorbed As, As coprecipitated in solids leachable by mild acids and reductants, and As incorporated in silicates and other more recalcitrant phases. One notable difference among depths is that sorbed As loads, considered with respect to solid phase Fe extractable with 1 N HCl, 0.2 M oxalic acid, and a 0.5 M Ti(III)-citrate-EDTA solution, appear to be at capacity at depths where aqueous As is highest; this suggests that sorption limitations may, in part, explain the aqueous As depth profile at this site. Competition for sorption sites by silicate, phosphate, and carbonate oxyanions appear to sustain elevated aqueous As levels in the upper aquifer. Furthermore, geochemical profiles are consistent with the hypothesis that past or ongoing reductive dissolution of Fe(III) oxyhydroxides acts synergistically with competitive sorption to maintain elevated dissolved As levels in the upper aquifer. Microprobe data indicate substantial spatial comapping between As and Fe in both the upper and deep aquifer sediments, and microscopic observations reveal ubiquitous Fe coatings on most solid phases, including quartz, feldspars, and aluminosilicates. Extraction results and XRD analysis of density/magnetic separates suggest that these coatings may comprise predominantly Fe(II) and mixed valence Fe solids, although the presence of Fe(III) oxyhydroxides can not be ruled out. These data suggest As release may continue to be linked to dissolution processes targeting Fe, or Fe-rich, phases in these aquifers.

Microstructure transformation of Cr-Al coating on carbon steel prepared by ball milling method as a function of tungsten doping

NASA Astrophysics Data System (ADS)

Wismogroho, A. S.; Sudiro, T.; Didik, A.; Ciswandi

2018-03-01

In present work, Cr-Al coatings containing 0, 1, 2, 3, and 5% W have been prepared on the surface of low carbon steel by mechanical alloying technique. The composition of each powder was milled for 2 hour in a stainless steel crucible with a ball to powder ratio of 10:1. Afterward, the Cr-Al-W powder and substrate were mechanically alloyed in air for 1 hour. The heat treatment of coated samples was carried out at 800 °C in a vacuum furnace for 2 hour. In order to characterize the phase composition and microstructure of the coating before and after heat treatment, XRD and SEM-EDX were used. The analysis results reveal that the ball milling process induces the formation of homogeneous Cr-Al-W coating structure with a thickness of about 80 μm. The phase observation shows individual peaks of each starting elements, along with the occurrence of powder refinement and solid solution formation. After heat treatment, AlCr2 and Al8Cr5 phases were formed. The addition of W accelerates the formation of AlCr2, but inhibits the formation of Al8Cr5. The detail of the results was presented in this paper.

Cr(VI) removal by FeS-coated alumina, silica, and natural sand

NASA Astrophysics Data System (ADS)

Park, M.; Lee, S.; Jeong, H. Y.

2014-12-01

Removal of Cr(VI) was investigated using mackinawite (FeS)-coated mineral sorbents under anoxic conditions. The sorbents included alumina (Al), silica (WS), and natural sand (NS). By analysis of both solution and solid phases, all FeS-coated sorbents were found to reduce Cr(VI) into Cr(III). The sorption extent and mechanism of Cr(VI) strongly depended on the pH conditions. Only at pH 4.5, significant amounts of the dissolved Cr remained in the solution. Titration of dissolved Cr(III) and Fe(III) by NaOH solutions indicated that no bulk-phase precipitation occurred at pH 4.5. Also, the removal of Cr(VI) at pH 4.5 was the greatest by FeS-coated NS. Consistent with these, Cr-K edge EXAFS revealed that Cr was removed by FeS-coated NS via surface precipitation, and that it was immobilized by FeS-coated WS and Al by forming surface clusters. Regardless of FeS-coated sorbents, at pH 7.0 and pH 9.5, the initially added Cr(VI) was quantitatively removed from the solution phase. By EXAFS analysis, the Cr sorption by FeS-coated Al was mainly due to the bulk-phase precipitation of Cr(OH)3(s) or [Cr, Fe](OH)3(s). In case of FeS-coated WS and NS, the short Cr-Cr distance (~2.6 Å) at pH 7.0 and pH 9.5 was not simply accounted for by the bulk precipitation as either hydroxide (rCr-Cr ~ 3.0 Å), and it would rather result from the surface precipitation. Such a difference in the coordination structure among FeS-coated sorbents was likely due to in the lower surface area of the former available for the surface precipitation.

DETECTION OF 2,4-DICHLOROPHENOXYACETIC ACID USING A FLUORESCENCE IMMUNOANALYZER

EPA Science Inventory

A flow immunoassay method for the measurement of 2,4-dichlorophenoxyacetic acid (2,4-D) was developed. The competitive fluorescence immunoassay relies on the use of antibody- or antigen-coated poly(methyl methacrylate) particles (98 um diameter) as a renewable solid phase. The as...

Thermal Effects on a Low Cr Modification of PS304 Solid Lubricant Coating

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.; Yanke, Anne M.; DellaCorte, Christopher

2004-01-01

PS304 is a high temperature composite solid lubricant coating composed of Ni-Cr, Cr2O3, BaF2-CaF2 and Ag. The effect of reducing chromium content on the formation of voids in the Ni-Cr particles after heat treatment in PS304 coating was investigated. Coatings were prepared with Ni-20Cr or Ni-10Cr powder and in various combinations with the other constituents of PS304 (i.e., chromia, silver and eutectic BaF2-CaF2 powders) and deposited on metal substrates by plasma spray. Specimens were exposed to 650 C for 24 hr or 1090 C for 15 hr and then examined for changes in thickness, coating microstructure and adhesion strength. Specimens with Ni-10Cr generally had less thickness increase than specimens with Ni-20Cr, but there was great variance in the data. Reduction of chromium concentration in Ni-Cr powder tended to reduce the appearance of voids in the Ni-Cr phase after heat exposure. The presence of BaF2-CaF2 resulted in a significant increase in coating adhesion strength after heat treatment, while coatings without BaF2-CaF2 had no significant change. Chemical composition analysis suggested that the void formation was due to oxidation of chromium in the Ni-Cr constituent.

Top-down solid-phase fabrication of nanoporous cadmium oxide architectures.

PubMed

Yu, Haidong; Wang, Deshen; Han, Ming-Yong

2007-02-28

In this article, we have demonstrated one-step solid-phase transformation from high-quality cadmium carbonate microcrystals into highly nanoporous cadmium oxide. The high crystal quality of cadmium carbonate is critical for the successful fabrication of porous nanoarchitectures with predetermined morphology and well-controlled internal structure. This novel strategy has a good potential to prepare nanoporous materials at a large scale by using perfect monolithic carbonate crystals, and it is also useful to synthesize different nanoporous materials on metal-oxide-coated substrates. Meanwhile, this simple thermal transformation of cadmium carbonate into porous structures has further been extended to convert calcium carbonate into such porous structures.

100% Solids Polyurethane Sequestration Coating

DTIC Science & Technology

2014-04-11

Distribution Unlimited 100% Solids Polyurethane Sequestration Coating The views, opinions and/or findings contained in this report are those of the...Papers published in non peer-reviewed journals: 100% Solids Polyurethane Sequestration Coating Report Title Report developed under Topic #CBD13-101...Final Technical Report Contract #: W911NF-13-P-0010 Proposal #: 63958CHSB1 Project: 100% Solids Polyurethane Sequestration Coating

Characterization of the aroma profile of novel Brazilian wines by solid-phase microextraction using polymeric ionic liquid sorbent coatings.

PubMed

Crucello, Juliana; Miron, Luiz F O; Ferreira, Victor H C; Nan, He; Marques, Marcia O M; Ritschel, Patricia S; Zanus, Mauro C; Anderson, Jared L; Poppi, Ronei J; Hantao, Leandro W

2018-05-28

In this study, a series of polymeric ionic liquid (PIL) sorbent coatings is evaluated for the extraction of polar volatile organic compounds (VOCs) from Brazilian wines using headspace solid-phase microextraction (HS-SPME), including samples from 'Isabella' and 'BRS Magna' cultivars-the latter was recently introduced by the Brazilian Agricultural Research Corporation - National Grape & Wine Research Center. The structurally tuned SPME coatings were compared to the commercial SPME phases, namely poly(acrylate) (PA) and divinylbenzene/carboxen/poly(dimethylsiloxane) (DVB/CAR/PDMS). The separation, detection and identification of the aroma profiles were obtained using comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS). The best performing PIL-based SPME fiber, namely 1-hexadecyl-3-vinylimidazolium bis[(trifluoromethyl)sulfonyl]imide with 1,12-di(3-vinylimidazolium)dodecane dibis[(trifluoromethyl)sulfonyl]imide incorporated cross-linker supported on an elastic nitinol wire, exhibited superior performance to DVB/CAR/PDMS regarding the average number of extracted peaks and extracted more polar analytes providing additional insight into the aroma profile of 'BRS Magna' wines. Four batches of wine were evaluated, namely 'Isabella' and 'BRS Magna' vintages 2015 and 2016, using highly selective PIL-based SPME coatings and enabled the detection of 350+ peaks. Furthermore, this is the first report evaluating the aroma of 'BRS Magna' wines. A hybrid approach that combined pixel-based Fisher ratio and peak table-based data comparison was used for data handling. This proof-of-concept experiment provided reliable and statistically valid distinction of wines that may guide regulation agencies to create high sample throughput protocols to screen wines exported by Brazilian vintners. Graphical abstract Highly selective extraction of wine aroma using polymeric ionic liquid.

A low-cost biosorbent-based coating for the highly sensitive determination of organochlorine pesticides by solid-phase microextraction and gas chromatography-electron capture detection.

PubMed

do Carmo, Sângela Nascimento; Merib, Josias; Dias, Adriana Neves; Stolberg, Joni; Budziak, Dilma; Carasek, Eduardo

2017-11-24

In this study, an environmentally friendly and low-cost biosorbent coating was evaluated, for the first time, as the extraction phase for solid-phase microextraction (SPME) supported on a nitinol alloy. The characterization of the new fiber was performed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The applicability of the biosorbent-based fiber in the determination of δ-hexachlorocyclohexane, aldrin, heptachlor epoxide, α-endosulfan, endrin and 4,4'-DDD in water samples was verified, with separation/detection by gas chromatography coupled to electron capture detection (GC-ECD). The influencing parameters (temperature, extraction time and ionic strength) were optimized simultaneously using a central composite design. The optimum conditions were: extraction time of 80min at 80°C and sodium chloride concentration of 15% (w/v). Satisfactory analytical performance was achieved with limits of detection (LOD) between 0.19 and 0.71ngL -1 and limits of quantification (LOQ) between 0.65 and 2.38ngL -1 . The relative recoveries for the analytes were determined using river and lake water samples spiked at different concentrations and ranged from 60% for α-endosulfan to 113% for δ-hexachlorocyclohexane, with relative standard deviations (RSD) lower than 21%. The fiber-to-fiber reproducibility (n=3) was also evaluated and the RSD was lower than 14%. The extraction efficiency obtained for the proposed biosorbent coating was compared to a commercially available DVB/Car/PDMS coating. The proposed fiber provided very promising results, including LODs at the level of parts per trillion and highly satisfactory thermal and mechanical stability. Copyright © 2017 Elsevier B.V. All rights reserved.

An Overview of 2014 SBIR Phase I and Phase II Materials Structures for Extreme Environments

NASA Technical Reports Server (NTRS)

Nguyen, Hung D.; Steele, Gynelle C.; Morris, Jessica R.

2015-01-01

NASA's Small Business Innovation Research (SBIR) program focuses on technological innovation by investing in development of innovative concepts and technologies to help NASA mission directorates address critical research needs for Agency programs. This report highlights nine of the innovative SBIR 2014 Phase I and Phase II projects that emphasize one of NASA Glenn Research Center's six core competencies-Materials and Structures for Extreme Environments. The technologies cover a wide spectrum of applications such as high temperature environmental barrier coating systems, deployable space structures, solid oxide fuel cells, and self-lubricating hard coatings for extreme temperatures. Each featured technology describes an innovation, technical objective, and highlights NASA commercial and industrial applications. This report provides an opportunity for NASA engineers, researchers, and program managers to learn how NASA SBIR technologies could help their programs and projects, and lead to collaborations and partnerships between the small SBIR companies and NASA that would benefit both.

Driving CO2 to a Quasi-Condensed Phase at the Interface between a Nanoparticle Surface and a Metal-Organic Framework at 1 bar and 298 K.

PubMed

Lee, Hiang Kwee; Lee, Yih Hong; Morabito, Joseph V; Liu, Yejing; Koh, Charlynn Sher Lin; Phang, In Yee; Pedireddy, Srikanth; Han, Xuemei; Chou, Lien-Yang; Tsung, Chia-Kuang; Ling, Xing Yi

2017-08-23

We demonstrate a molecular-level observation of driving CO 2 molecules into a quasi-condensed phase on the solid surface of metal nanoparticles (NP) under ambient conditions of 1 bar and 298 K. This is achieved via a CO 2 accumulation in the interface between a metal-organic framework (MOF) and a metal NP surface formed by coating NPs with a MOF. Using real-time surface-enhanced Raman scattering spectroscopy, a >18-fold enhancement of surface coverage of CO 2 is observed at the interface. The high surface concentration leads CO 2 molecules to be in close proximity with the probe molecules on the metal surface (4-methylbenzenethiol), and transforms CO 2 molecules into a bent conformation without the formation of chemical bonds. Such linear-to-bent transition of CO 2 is unprecedented at ambient conditions in the absence of chemical bond formation, and is commonly observed only in pressurized systems (>10 5 bar). The molecular-level observation of a quasi-condensed phase induced by MOF coating could impact the future design of hybrid materials in diverse applications, including catalytic CO 2 conversion and ambient solid-gas operation.

Cork as a new (green) coating for solid-phase microextraction: determination of polycyclic aromatic hydrocarbons in water samples by gas chromatography-mass spectrometry.

PubMed

Dias, Adriana Neves; Simão, Vanessa; Merib, Josias; Carasek, Eduardo

2013-04-15

A new fiber for solid-phase microextraction (SPME) was prepared employing cork as a coating. The morphology and composition of the cork fiber was evaluated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The proposed fiber was used for the determination of polycyclic aromatic hydrocarbons (PAHs) in river water samples by gas chromatography-selected ion monitoring-mass spectrometry (GC-SIM-MS). A central composite design was used for optimization of the variables involved in the extraction of PAHs from water samples. The optimal extraction conditions were extraction time and temperature of 60 min and 80°C, respectively. The detection and quantification limits were 0.03 and 0.1 μg L(-1), respectively. The recovery values were between 70.2 and 103.2% and the RSD was ≤15.7 (n=3). The linear range was 0.1-10 μg L(-1) with r≥0.96 and the fiber-to-fiber reproducibility showed RSD≤18.6% (n=5). The efficiency of the cork fiber was compared with commercially available fibers and good results were achieved, demonstrating the applicability and great potential of cork as a coating for SPME. Copyright © 2013 Elsevier B.V. All rights reserved.

Low-cost Scholl-coupling microporous polymer as an efficient solid-phase microextraction coating for the detection of light aromatic compounds.

PubMed

Xie, Xintong; Wang, Junhui; Zheng, Juan; Huang, Junlong; Ni, Chuyi; Cheng, Jie; Hao, Zhengping; Ouyang, Gangfeng

2018-10-31

A cost-effective microporous polymer was synthesized using cheap monomer and catalyst via one-step Scholl-coupling reaction, and its chemical, morphological characteristics and pore structure were investigated. The as-synthesized polymer with large surface area and narrow pore distribution (centered in 1.2 nm) was prepared as a fiber coating for solid-phase microextraction (SPME). Headspace SPME was used for the extraction of the light aromatic compounds, e.g. benzene, toluene, ethylbenzene, m-xylene, naphthalene and acenaphthene. The parameters influencing the extraction and desorption efficiencies, such as extraction temperature and time, salt concentration, desorption temperature and time were investigated and optimized. The results showed that the home-made fiber had superior extraction efficiencies compared with the commercial PDMS fiber. Under the optimized conditions, low detection limits (0.01-1.3 ng/L), wide linear ranges (from 50 to 20000 ng/L to 1-20000 ng/L), good repeatability (4.2-9.3%, n = 6) and reproducibility (0.30-11%, n = 3) were achieved. Moreover, the practical applicability of the coating and proposed method was evaluated by determining the target light aromatic compounds in environmental water samples with satisfied recoveries (83.2%-116%). Copyright © 2018 Elsevier B.V. All rights reserved.

Carbon coated magnetic nanoparticles as a novel magnetic solid phase extraction adsorbent for simultaneous extraction of methamphetamine and ephedrine from urine samples.

PubMed

Taghvimi, Arezou; Hamishehkar, Hamed

2017-01-15

This paper develops a highly selective, specific and efficient method for simultaneous determination of ephedrine and methamphetamine by a new carbon coated magnetic nanoparticles (C/MNPs) as a magnetic solid phase extraction (MSPE) adsorbent in biological urine medium. The characterization of synthesized magnetic nano adsorbent was completely carried out by various characterization techniques like Fourier transform infrared (FT-IR) spectroscopy, powder x-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Nine important parameters influencing extraction efficiency including amount of adsorbent, amounts of sample volume, pH, type and amount of extraction organic solvent, time of extraction and desorption, agitation rate and ionic strength of extraction medium, were studied and optimized. Under optimized extraction conditions, a good linearity was observed in the concentration range of 100-2000ng/mL for ephedrine and 100-2500ng/mL for methamphetamine. Analysis of positive urine samples was carried out by proposed method with the recovery of 98.71 and 97.87% for ephedrine and methamphetamine, respectively. The results indicated that carbon coated magnetic nanoparticles could be applied in clinical and forensic laboratories for simultaneous determination of abused drugs in urine media. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrafast Screening and Quantitation of Pesticides in Food and Environmental Matrices by Solid-Phase Microextraction-Transmission Mode (SPME-TM) and Direct Analysis in Real Time (DART).

PubMed

Gómez-Ríos, Germán Augusto; Gionfriddo, Emanuela; Poole, Justen; Pawliszyn, Janusz

2017-07-05

The direct interface of microextraction technologies to mass spectrometry (MS) has unquestionably revolutionized the speed and efficacy at which complex matrices are analyzed. Solid Phase Micro Extraction-Transmission Mode (SPME-TM) is a technology conceived as an effective synergy between sample preparation and ambient ionization. Succinctly, the device consists of a mesh coated with polymeric particles that extracts analytes of interest present in a given sample matrix. This coated mesh acts as a transmission-mode substrate for Direct Analysis in Real Time (DART), allowing for rapid and efficient thermal desorption/ionization of analytes previously concentrated on the coating, and dramatically lowering the limits of detection attained by sole DART analysis. In this study, we present SPME-TM as a novel tool for the ultrafast enrichment of pesticides present in food and environmental matrices and their quantitative determination by MS via DART ionization. Limits of quantitation in the subnanogram per milliliter range can be attained, while total analysis time does not exceed 2 min per sample. In addition to target information obtained via tandem MS, retrospective studies of the same sample via high-resolution mass spectrometry (HRMS) were accomplished by thermally desorbing a different segment of the microextraction device.

Polydimethylsiloxane/metal-organic frameworks coated fiber for solid-phase microextraction of polycyclic aromatic hydrocarbons in river and lake water samples.

PubMed

Zhang, Guijiang; Zang, Xiaohuan; Li, Zhi; Wang, Chun; Wang, Zhi

2014-11-01

In this study, polydimethylsiloxane/metal-organic frameworks (PDMS/MOFs), including PDMS/MIL-101 and PDMS/MOF-199, were immobilized onto a stainless steel wire through sol-gel technique as solid-phase microextraction (SPME) fiber coating. The prepared fibers were used for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from water samples prior to gas chromatography-mass spectrometry (GC-MS) analysis. Under the optimized experiment conditions, the PDMS/MIL-101 coated fiber exhibited higher extraction efficiency towards PAHs than that of PDMS/MOF-199. Several parameters affecting the extraction of PAHs by SPME with PDMS/MIL-101 fiber, including the extraction temperature, extraction time, sample volume, salt addition and desorption conditions, were investigated. The limits of detection (LODs) were less than 4.0 ng L(-1) and the linearity was observed in the range from 0.01 to 2.0 µg L(-1) with the correlation coefficients (r) ranging from 0.9940 to 0.9986. The recoveries of the method for the PAHs from water samples at spiking levels of 0.05 and 0.2 µg L(-1) ranged from 78.2% to 110.3%. Single fiber repeatability and fiber-to-fiber reproducibility were less than 9.3% and 13.8%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

BIOGEOCHEMICAL PROCESSES CONTROLLING ARSENIC SPECIATION AND BIOTRANSFORMATION IN GRANULAR FERRIC HYDROXIDE COATED SAND

EPA Science Inventory

Arsenic mobilization from solid phase Fe (III) hydroxides is an issue of concern, as water-borne arsenic can migrate into pristine environments, endangering aquatic and human life. In general, metal oxide (hydroxides) exerts a dominating effect on the fate and transport of arseni...

pH-resistant titania hybrid organic-inorganic sol-gel coating for solid-phase microextraction of polar compounds.

PubMed

Li, Xiujuan; Gao, Jie; Zeng, Zhaorui

2007-05-02

A novel titania-hydroxy-terminated silicone oil (titania-OH-TSO) sol-gel coating was developed for solid-phase microextraction of polar compounds. In general, titania-based sol-gel reaction is very fast and need to be decelerated by the use of suitable chelating agents. But in the present work, a judiciously designed sol solution ingredients was used to create the titania-OH-TSO coating without the addition of any chelating agent, which simplified the sol-gel procedure. Thanks to the variety of titania's adsorption sites and their acid-base characteristics, aromatic amines, phenols and polycyclic aromatic hydrocarbons were efficiently extracted and preconcentrated from aqueous samples followed by thermal desorption and GC analysis. The newly developed sol-gel hybrid titania coating demonstrated excellent pH stability, and retained its extraction characteristics intact even after continuous rinsing with a 3 M HCl or NaOH solution for 12 h. Furthermore, it could withstand temperatures as high as 320 degrees C. Practical application was demonstrated through the analysis of six aromatic amines in dye process wastewater. A linearity of four orders of magnitude was obtained with correlation coefficient better than 0.9982. The detection limits ranged from 0.22 to 0.84 microg L(-1) and the repeatability of the measurements was <7.0%. The recoveries of these compounds studied in the wastewater were in the ranges 83.6-101.4%, indicating the method accuracy.

Preparation of a polymeric ionic liquid-coated solid-phase microextraction fiber by surface radical chain-transfer polymerization with stainless steel wire as support.

PubMed

Feng, Juanjuan; Sun, Min; Xu, Lili; Li, Jubai; Liu, Xia; Jiang, Shengxiang

2011-10-28

Polymeric 1-vinyl-3-octylimidazolium hexafluorophosphate was synthesized in situ on stainless steel wire by surface radical chain-transfer polymerization and used as sensitive coatings in solid-phase microextraction. The outer surface of the stainless steel wire was firstly coated with microstructured silver layer via silver mirror reaction and then functionalized with self-assembled monolayers of 1,8-octanedithiol, which acted as chain transfer agent in the polymerization. Coupled to gas chromatography, extraction performance of the fiber was studied with both headspace and direct-immersion modes using benzene, toluene, ethylbenzene and xylenes (BTEX), phenols and polycyclic aromatic hydrocarbon (PAHs) as model analytes. In combination with the microstructured silver layer, the PIL-coated fiber exhibited high extraction efficiency. Linear ranges for BTEX with headspace mode were in the range of 0.2-1000 μg L(-1) for benzene, and 0.1-1000 μg L(-1) for toluene, ethylbenzene and xylenes. Limits of detection (LODs) were from 0.02 to 0.05 μg L(-1). Wide linear ranges of direct-immersion mode for the extraction of several phenols and PAHs were also obtained with correlation coefficients (R) from 0.9943 to 0.9997. The proposed fiber showed good durability with long lifetime. RSDs of 56 times extraction were still in an acceptable range, from 8.85 to 22.8%. Copyright © 2011 Elsevier B.V. All rights reserved.

Condensed-phase biogenic-anthropogenic interactions with implications for cold cloud formation

DOE PAGES

Charnawskas, Joseph C.; Alpert, Peter A.; Lambe, Andrew; ...

2017-01-24

Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil-fuel combustion can acquire a coating of SOA. We investigate SOA-soot biogenic-anthropogenic interactions and their impact on ice nucleation in relation to the particles’ organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without presence of sulfate or soot particles. Corresponding particle glass transition (T g) and full deliquescence relative humidity (FDRH) were estimated by a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfate mixtures exhibitmore » a core-shell configuration (i.e. a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation in agreement with respective T g and FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid inducing ice nucleation. Naphthalene SOA coated soot particles acted as IN above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate further renders this even less likely. Furthermore, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during preindustrial times or in pristine areas.« less

Condensed-phase biogenic–anthropogenic interactions with implications for cold cloud formation

DOE PAGES

Charnawskas, Joseph C.; Alpert, Peter A.; Lambe, Andrew T.; ...

2017-01-24

Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil fuel combustion can acquire a coating of SOA. We investigate SOA–soot biogenic–anthropogenic interactions and their impact on ice nucleation in relation to the particles’ organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without the presence of sulfate or soot particles. Corresponding particle glass transition (T g) and full deliquescence relative humidity (FDRH) were estimated using a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfatemore » mixtures exhibit a core–shell configuration (i.e.a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation, in agreement with respectiveT gand FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid, inducing ice nucleation. Naphthalene SOA coated soot particles acted as ice nuclei above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate renders this even less likely. However, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during pre-industrial times or in pristine areas.« less

Condensed-phase biogenic-anthropogenic interactions with implications for cold cloud formation.

PubMed

Charnawskas, Joseph C; Alpert, Peter A; Lambe, Andrew T; Berkemeier, Thomas; O'Brien, Rachel E; Massoli, Paola; Onasch, Timothy B; Shiraiwa, Manabu; Moffet, Ryan C; Gilles, Mary K; Davidovits, Paul; Worsnop, Douglas R; Knopf, Daniel A

2017-08-24

Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil fuel combustion can acquire a coating of SOA. We investigate SOA-soot biogenic-anthropogenic interactions and their impact on ice nucleation in relation to the particles' organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without the presence of sulfate or soot particles. Corresponding particle glass transition (T g ) and full deliquescence relative humidity (FDRH) were estimated using a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfate mixtures exhibit a core-shell configuration (i.e. a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation, in agreement with respective T g and FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid, inducing ice nucleation. Naphthalene SOA coated soot particles acted as ice nuclei above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate renders this even less likely. However, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during pre-industrial times or in pristine areas.

Preparation and characterization of polydimethylsiloxane/poly(vinylalcohol) coated solid phase microextraction fibers using sol-gel technology.

PubMed

Lopes, Alexandre Leite; Augusto, Fabio

2004-11-12

The applicability of a composite composed of polydimethylsiloxane (PDMS) and poly(vinyl alcohol) (PDMS/PVA) as coating sorbent for SPME fibers is demonstrated here. Fused silica (FS) fibers were coated with PDMS/PVA composite through a sol-gel process, using methyltrimethoxysilane as reticulating agent. The chemical and physical properties of the sol-gel PDMS/PVA composite were determined by infrared spectroscopy and thermogravimetric analysis. Electron scanning microscopy of the prepared fibers, showed that the coating obtained was highly microporous, having a thickness of approximately 5 microm. The fibers were tested for the headspace extraction of several organic compounds (o-xylene, naphthalene, ethyl caprate, p-chlorotoluene and PCB) prior to gas chromatographic analysis. The extractive capacity of the PDMS/PVA coating was found to be superior to that of pure conventional PDMS fibers.

A Novel Hybrid Axial-Radial Atmospheric Plasma Spraying Technique for the Fabrication of Solid Oxide Fuel Cell Anodes Containing Cu, Co, Ni, and Samaria-Doped Ceria

NASA Astrophysics Data System (ADS)

Cuglietta, Mark; Kuhn, Joel; Kesler, Olivera

2013-06-01

Composite coatings containing Cu, Co, Ni, and samaria-doped ceria (SDC) have been fabricated using a novel hybrid atmospheric plasma spraying technique, in which a multi-component aqueous suspension of CuO, Co3O4, and NiO was injected axially simultaneously with SDC injected radially in a dry powder form. Coatings were characterized for their microstructure, permeability, porosity, and composition over a range of plasma spray conditions. Deposition efficiency of the metal oxides and SDC was also estimated. Depending on the conditions, coatings displayed either layering or high levels of mixing between the SDC and metal phases. The deposition efficiencies of both feedstock types were strongly dependent on the nozzle diameter. Plasma-sprayed metal-supported solid oxide fuel cells utilizing anodes fabricated with this technique demonstrated power densities at 0.7 V as high as 366 and 113 mW/cm2 in humidified hydrogen and methane, respectively, at 800 °C.

Dry coating, a novel coating technology for solid pharmaceutical dosage forms.

PubMed

Luo, Yanfeng; Zhu, Jesse; Ma, Yingliang; Zhang, Hui

2008-06-24

Dry coating is a coating technology for solid pharmaceutical dosage forms derived from powder coating of metals. In this technology, powdered coating materials are directly coated onto solid dosage forms without using any solvent, and then heated and cured to form a coat. As a result, this technology can overcome such disadvantages caused by solvents in conventional liquid coating as serious air pollution, high time- and energy-consumption and expensive operation cost encountered by liquid coating. Several dry coating technologies, including plasticizer-dry-coating, electrostatic-dry-coating, heat-dry-coating and plasticizer-electrostatic-heat-dry-coating have been developed and extensively reported. This mini-review summarized the fundamental principles and coating processes of various dry coating technologies, and thoroughly analyzed their advantages and disadvantages as well as commercialization potentials.

Determination of arsenic and selenium by hydride generation and headspace solid phase microextraction coupled with optical emission spectrometry

NASA Astrophysics Data System (ADS)

Tyburska, Anna; Jankowski, Krzysztof; Rodzik, Agnieszka

2011-07-01

A hydride generation headspace solid phase microextraction technique has been developed in combination with optical emission spectrometry for determination of total arsenic and selenium. Hydrides were generated in a 10 mL volume septum-sealed vial and subsequently collected onto a polydimethylsiloxane/Carboxen solid phase microextraction fiber from the headspace of sample solution. After completion of the sorption, the fiber was transferred into a thermal desorption unit and the analytes were vaporized and directly introduced into argon inductively coupled plasma or helium microwave induced plasma radiation source. Experimental conditions of hydride formation reaction as well as sorption and desorption of analytes have been optimized showing the significant effect of the type of the solid phase microextraction fiber coating, the sorption time and hydrochloric acid concentration of the sample solution on analytical characteristics of the method developed. The limits of detection of arsenic and selenium were 0.1 and 0.8 ng mL - 1 , respectively. The limit of detection of selenium could be improved further using biosorption with baker's yeast Saccharomyces cerevisiae for analyte preconcentration. The technique was applied for the determination of total As and Se in real samples.

Advances in covalent organic frameworks in separation science.

PubMed

Qian, Hai-Long; Yang, Cheng-Xiong; Wang, Wen-Long; Yang, Cheng; Yan, Xiu-Ping

2018-03-23

Covalent organic frameworks (COFs) are a new class of multifunctional crystalline organic polymer constructed with organic monomers via robust covalent bonds. The unique properties such as convenient modification, low densities, large specific surface areas, good stability and permanent porosity make COFs great potential in separation science. This review shows the state-of-the art for the application of COFs and their composites in analytical separation science. COFs and their composites have been explored as promising sorbents for solid phase extraction, potential coatings for solid phase microextraction, and novel stationary phases for gas chromatography, high-performance liquid chromatography and capillary electrochromatography. The prospects of COFs for separation science are also presented, which can offer an outlook and reference for further study on the applications of COFs. Copyright © 2018 Elsevier B.V. All rights reserved.

Porous Aromatic Framework 48/Gel Hybrid Material Coated Solid-Phase Microextraction Fiber for the Determination of the Migration of Styrene from Polystyrene Food Contact Materials.

PubMed

Jin, Yuanyuan; Li, Zhongyue; Yang, Lei; Xu, Jun; Zhao, Le; Li, Zhonghao; Niu, Jiajia

2017-01-17

A novel solid-phase microextraction (SPME) fiber was fabricated by a porous aromatic framework 48 (PAF-48)/gel hybrid material through a sol-gel process. PAF-48 is a porous organic framework (POF) material that was polymerized from 1,3,5-triphenylbenzene. The uniform pore structure, high surface area, continuous conjugate network, and hydrophobicity make PAF-48 expected to have special abilities to absorb and extract styrene as well as some other harmful volatile aromatic compounds (VACs). The PAF-48/gel-coated fiber was explored for the extraction of styrene and six VACs (benzene, toluene, ethylbenzene, and xylenes) from aqueous food simulants followed by gas chromatography (GC) separation. The fiber was found to be very sensitive for the determination of the target molecules with wide linear ranges (0.1-200 or 500 μg·kg -1 ), low limits of detection (LODs, 0.003-0.060 μg·kg -1 ), acceptable precisions (intraday relative standard deviation, RSD < 5.9%, interday RSD < 7.3%), and long lifetime (>200 times). Particularly for styrene, the PAF-48/gel-coated fiber exhibited a much lower LOD (0.006 μg·kg -1 ) compared with most of the reported fibers. Moreover, the PAF-48/gel-coated fiber had a high extraction selectivity for styrene and VACs over alcohols, phenols, aromatic amines, and alkanes and show a molecular sieving effect for the different molecule sizes. Finally, the PAF-48/gel-coated SPME fiber was successfully applied in GC for the determination of the specific migrations of styrene and VACs from polystyrene (PS) plastic food contact materials (FCMs).

Geometrical control of dissipation during the spreading of liquids on soft solids

NASA Astrophysics Data System (ADS)

Zhao, Menghua; Dervaux, Julien; Narita, Tetsuharu; Lequeux, François; Limat, Laurent; Roché, Matthieu

2018-02-01

Gel layers bound to a rigid substrate are used in cell culture to control differentiation and migration and to lower the friction and tailor the wetting of solids. Their thickness, often considered a negligible parameter, affects cell mechanosensing or the shape of sessile droplets. Here, we show that the adjustment of coating thickness provides control over energy dissipation during the spreading of flowing matter on a gel layer. We combine experiments and theory to provide an analytical description of both the statics and the dynamics of the contact line between the gel, the liquid, and the surrounding atmosphere. We extract from this analysis a hitherto-unknown scaling law that predicts the dynamic contact angle between the three phases as a function of the properties of the coating and the velocity of the contact line. Finally, we show that droplets moving on vertical substrates coated with gel layers having linear thickness gradients drift toward regions of higher energy dissipation. Thus, thickness control opens the opportunity to design a priori the path followed by large droplets moving on gel-coated substrates. Our study shows that thickness is another parameter, besides surface energy and substrate mechanics, to tune the dynamics of liquid spreading and wetting on a compliant coating, with potential applications in dew collection and free-surface flow control.

Automated headspace solid-phase dynamic extraction to analyse the volatile fraction of food matrices.

PubMed

Bicchi, Carlo; Cordero, Chiara; Liberto, Erica; Rubiolo, Patrizia; Sgorbini, Barbara

2004-01-23

High concentration capacity headspace techniques (headspace solid-phase microextraction (HS-SPME) and headspace sorptive extraction (HSSE)) are a bridge between static and dynamic headspace, since they give high concentration factors as does dynamic headspace (D-HS), and are as easy to apply and as reproducible as static headspace (S-HS). In 2000, Chromtech (Idstein, Germany) introduced an inside-needle technique for vapour and liquid sampling, solid-phase dynamic extraction (SPDE), also known as "the magic needle". In SPDE, analytes are concentrated on a 50 microm film of polydimethylsiloxane (PDMS) and activated carbon (10%) coated onto the inside wall of the stainless steel needle (5 cm) of a 2.5 ml gas tight syringe. When SPDE is used for headspace sampling (HS-SPDE), a fixed volume of the headspace of the sample under investigation is sucked up an appropriate number of times with the gas tight syringe and an analyte amount suitable for a reliable GC or GC-MS analysis accumulates in the polymer coating the needle wall. This article describes the preliminary results of both a study on the optimisation of sampling parameters conditioning HS-SPDE recovery, through the analysis of a standard mixture of highly volatile compounds (beta-pinene, isoamyl acetate and linalool) and of the HS-SPDE-GC-MS analyses of aromatic plants and food matrices. This study shows that HS-SPDE is a successful technique for HS-sampling with high concentration capability, good repeatability and intermediate precision, also when it is compared to HS-SPME.

Carbide and nitride precipitation during laser cladding of Inconel 718 alloy coatings

NASA Astrophysics Data System (ADS)

Zhang, Yaocheng; Li, Zhuguo; Nie, Pulin; Wu, Yixiong

2013-11-01

The microstructure of the laser clad Inconel 718 alloy coating was observed by scanning electron microscope (SEM). The chemical composition of precipitation phases was investigated by energy dispersive spectrometer (EDS) and solid phase microextraction (SPME). The crystal structure and lattice constants of precipitation are determined by transmission electron microscope (TEM). Vickers hardness of the coatings and the nanohardness of the interstitial phases were measured. The insular carbide (MC) and the tetragonal nitride (MN) with face-centered cubic (FCC) structure are rich in Ti and Nb but depleted in Ni, Fe and Cr due to the interdiffusion and redistribution of alloying elements between MC and MN and supersaturated matrix. MC and MN were precipitated in the forms of (Nb0.12Ti0.88)C1.5 and (Nb0.88Ti0.12)N1.5, and the Gibbs free energies of formation can be expressed as Δ G [ (Nb0.12Ti0.88)C1.5 ] 0 = - 122.654 - 3.1332 T (kJ /mol) and Δ G [ (Nb0.88Ti0.12)N1.5 ] 0 = - 157.814 - 3.0251 T (kJ /mol). The nanohardness and Young's modulus of the MC and MN were much higher than the matrix, and the plastic deformation energy of interstitial phases was lower than the matrix. The precipitation of MC and MN is beneficial to the mechanical properties of coating.

Preparation of immobilized coating Fenton-like catalyst for high efficient degradation of phenol.

PubMed

Wang, Jiankang; Yao, Zhongping; Wang, Yajing; Xia, Qixing; Chu, Huiya; Jiang, Zhaohua

2017-05-01

In this study, solid acid amorphous Fe 3 O 4 /SiO 2 ceramic coating decorated with sulfur on Q235 carbon steel as Fenton-like catalyst for phenol degradation was successfully prepared by plasma electrolytic oxidation (PEO) in silicate electrolyte containing Na 2 S 2 O 8 as sulfur source. The surface morphology and phase composition were characterized by SEM, EDS, XRD and XPS analyses. NH 3 -TPD was used to evaluate surface acidity of PEO coating. The results indicated that sulfur decorated amorphous Fe 3 O 4 /SiO 2 ceramic coatings with porous structure and higher acid strength had the similar pore size and the surface became more and more uneven with the increase of Na 2 S 2 O 8 in the silicate electrolyte. The Fenton-like catalytic activity of sulfur decorated PEO coatings was also evaluated. In contrast to negligible catalytic activity of sulfur undecorated PEO coating, catalytic activity of sulfur decorated PEO coating was excellent and PEO coating prepared with 3.0 g Na 2 S 2 O 8 had the highest catalytic activity which could degrade 99% of phenol within 8 min under circumneutral pH. The outstanding performance of sulfur decorated PEO coating was attributed to strong acidic microenvironment and more Fe 2+ on the surface. The strong acid sites played a key factor in determining catalytic activity of catalyst. In conclusion, rapid phenol removal under circumneutral pH and easier separation endowed it potential application in wastewater treatment. In addition, this strategy of preparing immobilized solid acid coating could provide guidance for designing Fenton-like catalyst with excellent catalytic activity and easier separation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dendronization-induced phase-transfer, stabilization and self-assembly of large colloidal Au nanoparticles

NASA Astrophysics Data System (ADS)

Malassis, Ludivine; Jishkariani, Davit; Murray, Christopher B.; Donnio, Bertrand

2016-07-01

The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates.The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates. Electronic supplementary information (ESI) available: TEM microscope images. See DOI: 10.1039/c6nr03404g

Heat-shrink tubing as a solid-phase microextraction coating for the enrichment and determination of phthalic acid esters.

PubMed

Luo, Xi; He, Chengxia; Zhang, Feifang; Wang, Hailong; Yang, Bingcheng; Liang, Xinmiao

2014-12-01

Heat-shrink tubing, which shrinks in one plane only (its diameter) when heated, commonly used for sealing protection in electrical engineering, was found to be able to function as a solid-phase microextraction coating. Its utility was demonstrated for the determination of phthalic acid esters in an aqueous solution combined with high-performance liquid chromatography equipped with a UV absorbance detector. The preparation procedure was rather simple and only ∼10 min was needed. The fiber cost is extremely low (∼10 cent each). The parameters affecting the extraction were optimized. Heat-shrink tubing fiber exhibited a significant enrichment effect for the three examined phthalic acid esters and up to 931-fold enrichment factor was obtained. The limit of detection was <10 μg/L for all analytes. The operation repeatability and fiber-to-fiber reproducibility were 1.2-8.3 and 5.4-9.1%, respectively. It was successfully applied for the analysis of bottled drinking water with recoveries ranging from 90.1-100.5%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid-phase microextraction of phthalate esters by a new coating based on a thermally stable polypyrrole/graphene oxide composite.

PubMed

Jafari, Mostafa; Ebrahimzadeh, Homeira; Banitaba, Mohammad Hossein; Davarani, Saied Saeed Hosseiny

2014-11-01

A novel polypyrole/graphene oxide coating was made by the electrochemical polymerization of pyrrole in the presence of sodium dodecyl sulfate and graphene oxide on a platinum wire. The prepared fiber has shown a good thermal stability up to 300°C. The fiber was applied to the direct solid-phase microextraction and gas chromatographic analysis of four phthalate esters. The effect of four parameters on gas chromatography peak area including extraction temperature, extraction time, injection temperature, and ionic strength were investigated. Under the optimized conditions, the detection limits were between 0.042 and 0.26 μg/L. The intraday and interday relative standard deviations obtained at 55 μg/L, using a single fiber, were 8.2-16% and 17.3-25.6%, respectively. The method was successfully applied to the analysis of phthalate esters in two real samples of boiling water in cheap disposable clear plastic drinking cups showing recoveries from 83 to 120%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enrichment and determination of octylphenol and nonylphenol in environmental water samples by solid-phase microextraction with carboxylated carbon nano-spheres coating prior to gas chromatography-mass spectrometry.

PubMed

Gong, Sheng-Xiang; Wang, Xia; Li, Lei; Wang, Ming-Lin; Zhao, Ru-Song

2015-11-01

In this paper, a novel and simple method for the sensitive determination of endocrine disrupter compounds octylphenol (OP) and nonylphenol (NP) in environmental water samples has been developed using solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry. Carboxylated carbon nano-spheres (CNSs-COOH) are used as a novel SPME coating via physical adhesion. The CNSs-COOH fiber possessed higher adsorption efficiency than 100 μm polydimethysiloxane (PDMS) fiber and was similar to 85 μm polyacrylate (PA) fiber for the two analytes. Important parameters, such as extraction time, pH, agitation speed, ionic strength, and desorption temperature and time, were investigated and optimized in detail. Under the optimal parameters, the developed method achieved low limits of detection of 0.13~0.14 ng·L(-1) and a wide linear range of 1~1000 ng·(-1) for OP and NP. The novel method was validated with several real environmental water samples, and satisfactory results were obtained.

Liquid-Solid Self-Lubricated Coatings

NASA Astrophysics Data System (ADS)

Armada, S.; Schmid, R.; Equey, S.; Fagoaga, I.; Espallargas, N.

2013-02-01

Self-lubricated coatings have been a major topic of interest in thermal spray in the last decades. Self-lubricated coatings obtained by thermal spray are exclusively based on solid lubricants (PTFE, h-BN, graphite, MoS2, etc.) embedded in the matrix. Production of thermal spray coatings containing liquid lubricants has not yet been achieved because of the complexity of keeping a liquid in a solid matrix during the spraying process. In the present article, the first liquid-solid self-lubricating thermal spray coatings are presented. The coatings are produced by inserting lubricant-filled capsules inside a polymeric matrix. The goal of the coating is to release lubricant to the system when needed. The first produced coatings consisted solely of capsules for confirming the feasibility of the process. For obtaining such a coating, the liquid-filled capsules were injected in the thermal spray flame without any other feedstock material. Once the concept and the idea were proven, a polymer was co-sprayed together with the capsules to obtain a coating containing the lubricant-filled capsules distributed in the solid polymeric matrix. The coatings and the self-lubricated properties have been investigated by means of optical microscopy, Scanning Electron Microscopy, and tribological tests.

Effect of Nano-Y2O3 on Microstructure and Crack Formation in Laser Direct-Deposited In Situ Particle-Reinforced Fe-Based Coatings

NASA Astrophysics Data System (ADS)

Yin, Guili; Chen, Suiyuan; Liu, Yuanyuan; Liang, Jing; Liu, Changsheng; Kuang, Zheng

2018-03-01

In situ hard-particle-reinforced Fe-based composite coatings were prepared on Q235 steel substrates by direct laser deposition using Fe-based alloy powders containing 2 wt.% B, 3 wt.% Si and 1-3 wt.% nano-Y2O3. The microstructures, phase compositions, hardnesses and wear resistances of the deposited coatings with different nano-Y2O3 contents were studied using metallographic microscopy, scanning electron microscopy, x-ray diffraction, transmission electron microscopy, microhardness tests and pin-on-disk abrasion tests (MMW-1A), respectively. The results showed that the appropriate addition of Y2O3 played a role in grain refinement and in decreasing the number of brittle phases and impurity elements in the grain boundaries. Consequently, the number of cracks in the laser-deposited coating also decreased. The Fe-based composite coatings were mainly composed of α-Fe, γ-Fe and in situ-produced reinforced particle phases, such as Cr23C6, Cr7C3, (Cr, Fe)7C3, Fe2B, and CrFeB. When the content of nano-Y2O3 was 2 wt.%, a Fe-based composite coating with a thickness of 4 mm that was free of cracks was obtained, and its surface hardness reached 650HV. Moreover, the wear resistance of the coating with 2 wt.% nano-Y2O3 was the best among the samples studied. The presence of nano-Y2O3 increased the solubility of Cr and Si in the solid solution, which eliminated the residual austenite region, and as a result, the phase transformation from γ-Fe to α-Fe was restrained and the transformation stress was also limited, thereby decreasing the probability of cracks in the coatings.

Tribological Behavior of IN718 Superalloy Coating Fabricated by Laser Additive Manufacturing

NASA Astrophysics Data System (ADS)

Zhang, Yaocheng; Pan, Qiyong; Yang, Li; Li, Ruifeng; Dai, Jun

2017-12-01

The tribological behavior of laser manufactured IN718 superalloy coating are investigated with different applied loads, sliding speeds and lubricating mediums. The wear resistance of laser manufactured IN718 coating is increased by heat treatment due to higher microhardness and homogeneous brittle phase distribution. The principal factors for the wear rate are applied load and lubricating medium. The worn surface of laser manufactured IN718 coating consists of the grooves, crack, wear debris and material delamination generated by the fatigue wear associated with adhesive wear and abrasive wear. The friction coefficients are influenced by the tribological noise decrescence by the tribo-oxidant and the liquid lubricant. The real contact temperature between coating sample and frictional counterpart is higher than the solid-solution temperature of IN718 superalloy, and the effect of surface contact temperature on the orientational microstructure and wear resistance for dry friction and wet friction process is indistinct.

A new thermally immobilized fluorinated stationary phase for RP-HPLC.

PubMed

Maldaner, Liane; Jardim, Isabel C S F

2010-02-01

A new fluorinated stationary phase was prepared through thermal immobilization of poly(methyl-3,3,3-trifluoropropylsiloxane) onto 5 microm Kromasil silica particles. The best conditions of immobilization time and temperature were determined through a central composite design and response surface methodologies. Physical-chemical characterization using solid-state (29)Si NMR measurements, infrared spectroscopy and elemental analysis showed that the immobilization process was effective to promote a coating of the support that corresponds to a monolayer of polymer. The stationary phase presents selectivity for positional isomers and good peak shape for basic compounds.

Corrosion Resistance Characterization of Coating Systems Used to Protect Aluminum Alloys Using Electrochemical Impedance Spectroscopy and Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Gambina, Federico

In this study, the corrosion protection provided by of a number of chromate and chromate-free coatings systems was characterized in detail. High-solids SrCrO4-pigmented epoxy primers applied to 2024 and 7075 substrates were subject to salt spray exposure testing for 30 days. Samples were removed periodically and an electrochemical impedance measurement (EIS) was made. Although none of the coatings tested showed visual evidence of corrosion, the total impedance of the samples decreased by as much as two orders of magnitude. An analysis of capacitance showed that the primer coatings rapidly took up water from the exposure environment, but the coating-metal remained passive despite the fact that it was wet. These results support the idea that chromate coatings protect by creating a chromate-rich electrolyte within the coating that is passivating to the underlying metal substrate. They also suggest that indications of metal substrate passivity found in the low-frequency capacitive reactance of the impedance spectra are a better indicator of corrosion protection than the total impedance. The low-frequency capacitive reactance from EIS measurements is also good at assessing the protectiveness of chromate-free coatings systems. Fifteen different coatings systems comprising high-solids, chromate-free primers and chromate-free conversion coatings were applied to 2024 and 7075 substrates. These coatings were subject to salt spray exposure and EIS measurements. All coatings were inferior to coating systems containing chromate, but changes in the capacitive reactance measured in EIS was shown to anticipate visual indications of coating failure. A predictive model based on neural networks was trained to recognize the pattern in the capacitive reactance in impedance spectra measured after 48 hours of exposure and make an estimate of remaining coating life. A sensitivity analysis was performed to prune the impedance inputs. As a result of this analysis, a very simple but highly predictive model was constructed that used low-frequency phase angle information extracted directly from EIS measurements to predict time to failure in salt spray up to 30 days of exposure. The exposure and EIS characterization of the chromate-free coatings systems enabled a ranking of the coatings systems in terms of corrosion protection provided. Coating systems were ranked according to several different methods described in the literature. Among the coatings evaluated, Deft 02GN084, a high solids, solvent-borne and Pr-containing primer coating showed best protection when used in conjunction with a number of different conversion coatings and surface pretreatments. Several different trivalent chromium conversion coatings and pretreatment were used. This general type of conversion coating appeared to provide better corrosion protection than other pretreatments whose functions were primarily surface cleaning or adhesion promotion.

Electrochemical and solid-state NMR studies on LiCoO 2 coated with Al 2O 3 derived from carboxylate-alumoxane

NASA Astrophysics Data System (ADS)

Fey, George T. K.; Kao, H. M.; Muralidharan, P.; Kumar, T. P.; Cho, Y. D.

The surface of LiCoO 2 cathodes was coated with various wt.% of Al 2O 3 derived from methoxyethoxy acetate-alumoxane (MEA-alumoxane) by a mechano-thermal coating procedure, followed by calcination at 723 K in air for 10 h. The structure and morphology of the surface modified LiCoO 2 samples have been characterized with XRD, SEM, EDS, TEM, BET, XPS/ESCA and solid-state 27Al magic angle spinning (MAS) NMR techniques. The Al 2O 3 coating forms a thin layer on the surface of the core material with an average thickness of 20 nm. The corresponding 27Al MAS NMR spectrum basically exhibited the same characteristics as the spectrum for pristine Al 2O 3 derived from MEA-alumoxane, indicating that the local environment of aluminum atoms was not significantly changed at coating levels below 1 wt.%. This provides direct evidence that Al 2O 3 was on the surface of the core materials. The LiCoO 2 coated with 1 wt.% Al 2O 3 sustained continuous cycle stability 13 times longer than pristine LiCoO 2. A comparison of the electrochemical impedance behavior of the pristine and coated materials revealed that the failure of pristine cathode performance is associated with an increase in the particle-particle resistance upon continuous cycling. Coating improved the cathode performance by suppressing the characteristic structural phase transitions (hexagonal to monoclinic to hexagonal) that occur in pristine LiCoO 2 during the charge-discharge processes.

The improvement of moisture resistance and thermal stability of Ca 3SiO 4Cl 2:Eu 2+ phosphor coated with SiO 2

NASA Astrophysics Data System (ADS)

Zhuang, Jiaqing; Xia, Zhiguo; Liu, Haikun; Zhang, Zepeng; Liao, Libing

2011-02-01

Green-emitting phosphors Ca3SiO4Cl2:Eu2+ were prepared by the high temperature solid-state method. Sol-gel process was adopted to encapsulate the as-prepared phosphors with tetraethylorthosilicate (TEOS) as silicon coating reagent. Fluorescence spectrometer, scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) patterns were employed to characterize the emission spectra, the surface morphologies and the phase structures, respectively. The chemical stability testing was operated by the method of soaking the phosphors in deionized water and roasting them at different temperatures. The results indicated that the surfaces of the green phosphors were evenly coated by SiO2 and the phase structure of the coated phosphors remained the same as the uncoated samples. The luminance centre of Eu2+ did not shift after surface treatment and the luminance intensity of coated phosphors was lower than that of the uncoated samples. The results demonstrated that the water-resistance stability of the coated phosphor was improved to some degree because the pH value and the luminance intensity variation were both smaller than the uncoated phosphor after steeping within the same time. Moreover, the thermal stability of coated phosphors was enhanced obviously compared to the original samples based on the temperature dependent emission spectra measurement.

Microphase separation in solid lipid dosage forms as the cause of drug release instability.

PubMed

Lopes, Diogo Gomes; Koutsamanis, Ioannis; Becker, Karin; Scheibelhofer, Otto; Laggner, Peter; Haack, Detlev; Stehr, Michael; Zimmer, Andreas; Salar-Behzadi, Sharareh

2017-01-30

Although lipid excipients are of increasing interest for development of taste-masked and modified release formulations, the drug release instability and the lack of mechanistic understanding in that regard still prevent their larger-scale application. In this work, we investigated the physical stability of a binary (tripalmitin/polysorbate 65) lipid coating formulation with a known stable polymorphism. The coating composition was characterized using DSC to construct the phase diagram of binary system and polarized light microscopy to display the microstructure organization. The water uptake and the erosion of slabs cast from the coating formulations were investigated post-production and after storage. Subsequently, N-acetylcysteine particles were coated with the selected formulations and the drug release stability was investigated. Additionally, microstructure characterization was performed via SEM and X-ray diffraction. The drug release instability was explained by polysorbate 65 and tripalmitin phase growth during storage, especially at 40°C, suggesting that polysorbate 65 can leak out of tripalmitin spherulitic structures, creating lipophilic and impermeable tripalmitin regions. The growth of polysorbate 65 phase leads to larger hydrophilic channels with reduced tortuosity. This work indicates that for obtaining stable drug release profiles from advanced lipid formulations, microphase separation should be prevented during storage. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrochemical in situ fabrication of titanium dioxide-nanosheets on a titanium wire as a novel coating for selective solid-phase microextraction.

PubMed

Li, Yi; Zhang, Min; Yang, Yaoxia; Wang, Xuemei; Du, Xinzhen

2014-09-05

A novel TiO2-nanosheets coated fiber for solid-phase microextraction (SPME) was fabricated by anodization of Ti wire substrates in ethylene glycol with concentrated NH4F. The in situ fabricated TiO2-nanosheets were densely embedded into Ti substrates with about 1μm long, 300nm wide and 80nm thick. The as-fabricated TiO2-nanosheets coating was employed to extract polycyclic aromatic hydrocarbons, phthalates and ultraviolet (UV) filters in combination with high performance liquid chromatography-UV detection (HPLC-UV). It was found that the TiO2-nanosheets coating exhibited high extraction capability and good selectivity for some UV filters frequently used in cosmetic sunscreen formulations. The main parameters affecting extraction performance were investigated and optimized. Under the optimized conditions, the calibration graphs were linear in the range of 0.1-400μgL(-1). The limits of detection of the proposed method were between 0.026μgL(-1) and 0.089μgL(-1) (S/N=3). The single fiber repeatability varied from 4.50% to 8.76% and the fiber-to-fiber reproducibility ranged from 7.75% to 9.64% for the extraction of spiked water with 50μgL(-1) UV filters (n=5). The SPME-HPLC-UV method was successfully established for the selective preconcentration and sensitive detection of target UV filters from real environmental water samples. Recovery of UV filters spiked at 10μgL(-1) and 25μgL(-1) ranged from 88.8% to 107% and the relative standard deviations were less than 9.8%. Furthermore the in situ growth of the TiO2-nanosheets coating was performed in a highly reproducible manner and the TiO2-nanosheets coated fiber has high mechanical strength, good stability and long service life. Copyright © 2014 Elsevier B.V. All rights reserved.

Utilization of highly robust and selective crosslinked polymeric ionic liquid-based sorbent coatings in direct-immersion solid-phase microextraction and high-performance liquid chromatography for determining polar organic pollutants in waters.

PubMed

Pacheco-Fernández, Idaira; Najafi, Ali; Pino, Verónica; Anderson, Jared L; Ayala, Juan H; Afonso, Ana M

2016-09-01

Several crosslinked polymeric ionic liquid (PIL)-based sorbent coatings of different nature were prepared by UV polymerization onto nitinol wires. They were evaluated in a direct-immersion solid-phase microextraction (DI-SPME) method in combination with high-performance liquid chromatography (HPLC) and diode array detection (DAD). The studied PIL coatings contained either vinyl alkyl or vinylbenzyl imidazolium-based (ViCnIm- or ViBCnIm-) IL monomers with different anions, as well as different dicationic IL crosslinkers. The analytical performance of these PIL-based SPME coatings was firstly evaluated for the extraction of a group of 10 different model analytes, including hydrocarbons and phenols, while exhaustively comparing the performance with commercial SPME fibers such as polydimethylsyloxane (PDMS), polyacrylate (PA) and polydimethylsiloxane/divinylbenzene (PDMS/DVB), and using all fibers under optimized conditions. Those fibers exhibiting a high selectivity for polar compounds were selected to carry out an analytical method for a group of 5 alkylphenols, including bisphenol-A (BPA) and nonylphenol (n-NP). Under optimum conditions, average relative recoveries of 108% and inter-day precision values (3 non-consecutive days) lower than 19% were obtained for a spiked level of 10µgL(-1). Correlations coefficients for the overall method ranged between 0.990 and 0.999, and limits of detection were down to 1µgL(-1). Tap water, river water, and bottled water were analyzed to evaluate matrix effects. Comparison with the PA fiber was also performed in terms of analytical performance. Partition coefficients (logKfs) of the alkylphenols to the SPME coating varied from 1.69 to 2.45 for the most efficient PIL-based fiber, and from 1.58 to 2.30 for the PA fiber. These results agree with those obtained by the normalized calibration slopes, pointing out the affinity of these PILs-based coatings. Copyright © 2016 Elsevier B.V. All rights reserved.

Multiwalled carbon nanotubes coated fibers for solid-phase microextraction of polybrominated diphenyl ethers in water and milk samples before gas chromatography with electron-capture detection.

PubMed

Wang, Jun-Xia; Jiang, Dong-Qing; Gu, Zhi-Yuan; Yan, Xiu-Ping

2006-12-22

Determination of polybrominated diphenyl ethers (PBDEs) in environmental samples has raised great concerns due to the widespread use of PBDEs and their potential risk to humans. Solid-phase microextraction (SPME) is a fast, simple, cost-effective, and green sample preparation technique and is widely used for environmental analysis, but reports on the application of SPME for determination of PBDEs are very limited, and only a few publications dealing with commercial SPME fibers are available for extraction of PBDEs. Herein, we report a novel SPME method using multiwalled carbon nanotubes (MWCNTs) as the SPME fiber coating for gas chromatography with electron-capture detection (GC-ECD) of PBDEs in environmental samples. The MWCNTs coating gave much higher enhancement factors (616-1756) than poly (5% dibenzene-95% dimethylsiloxane) coating (139-384) and activated carbon coating (193-423). Thirty-minute extraction of 10 mL of sample solution using the MWCNTs coated fiber for GC-ECD determination yielded the limits of detection of 3.6-8.6 ng L(-1) and exhibited good linearity of the calibration functions (r(2)>0.995). The precision (RSD%, n=4) for peak area and retention time at the 500 ng L(-1) level was 6.9-8.8% and 0.6-0.9%, respectively. The developed method was successfully applied for the analysis of real samples including local river water, wastewater, and milk samples. The recovery of the PBDEs at 500 ng L(-1) spiked in these samples ranged from 90 to 119%. No PBDEs were detected in the river water and skimmed milk samples, whereas in the wastewater sample, 134-215 ng L(-1) of PBDEs were found. The PBDEs were detected in all whole fat milk samples, ranging from 13 to 484 ng L(-1). In a semiskimmed milk sample, only BDE-47 was found at 21 ng L(-1).

Extraction of ochratoxin A in red wine with dopamine-coated magnetic multi-walled carbon nanotubes.

PubMed

Wan, Hong; Zhang, Bo; Bai, Xiao-Lin; Zhao, Yan; Xiao, Meng-Wei; Liao, Xun

2017-10-01

A new, rapid, green, and cost-effective magnetic solid-phase extraction of ochratoxin A from red wine samples was developed using polydopamine-coated magnetic multi-walled carbon nanotubes as the absorbent. The polydopamine-coated magnetic multi-walled carbon nanotubes were fabricated with magnetic multi-walled carbon nanotubes and dopamine by an in situ oxidative self-polymerization approach. Transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy and vibrating sample magnetometry were used to characterize the absorbents. Ochratoxin A was quantified with high-performance liquid chromatography coupled with fluorescence detection, with excitation and emission wavelengths of 338 and 455 nm, respectively. The conditions affecting the magnetic solid-phase extraction procedure, such as pH, extraction solution, extraction time, absorbent amount, desorption solution and desorption time were investigated to obtain the optimal extraction conditions. Under the optimized conditions, the extraction recovery was 91.8-104.5% for ochratoxin A. A linear calibration curve was obtained in the range of 0.1-2.0 ng/mL. The limit of detection was 0.07 ng/mL, and the limit of quantitation was 0.21 ng/mL. The recoveries of ochratoxin A for spiked red wine sample ranged from 95.65 to 100.65% with relative standard deviation less than 8%. The polydopamine-coated magnetic multi-walled carbon nanotubes showed a high affinity toward ochratoxin A, allowing selective extraction and quantification of ochratoxin A from complex sample matrixes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Halloysite nanotubes-titanium dioxide as a solid-phase microextraction coating combined with negative corona discharge-ion mobility spectrometry for the determination of parathion.

PubMed

Saraji, Mohammad; Jafari, Mohammad Taghi; Mossaddegh, Mehdi

2016-07-05

Halloysite nanotubes-titanium dioxide (HNTs-TiO2) as a biocompatible environmentally friendly solid-phase microextraction (SPME) fiber coating was prepared. HNTs-TiO2 was chemically coated on the surface of a fused-silica fiber using a sol-gel process. Parathion as an organophosphorus pesticide was selected as a model compound to investigate the extraction efficiency of the fiber. The extracted analyte was detected by negative corona discharge-ion mobility spectrometer (NCD-IMS). The effective parameters on the extraction efficiency, such as salt effect, extraction temperature and extraction time were investigated and optimized. The extraction efficiency of HNTs-TiO2 fiber was compared with bare-silica (sol-gel based coating without HNTs-TiO2), HNTs, carbon nanotubes and commercial SPME fibers (PA, PDMS, and PDMS-DVB). The HNTs-TiO2 fiber showed highest extraction efficiency among the studied fibers. The intra- and inter-day relative standard deviations were found to be 4.3 and 6.3%, respectively. The limit of detection and limit of quantification values were 0.03 and 0.1 μg L(-1), respectively. The dynamic range of the method was in the range of 0.1-25 μg L(-1). The spiking recoveries were between 85 (±9) and 97 (±6). The SPME-HNTs-TiO2 combined with NCD-IMS was successfully applied for the determination of parathion in apple, strawberry, celery and water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

In Situ Hydrothermally Grown TiO2@C Core-Shell Nanowire Coating for Highly Sensitive Solid Phase Microextraction of Polycyclic Aromatic Hydrocarbons.

PubMed

Wang, Fuxin; Zheng, Juan; Qiu, Junlang; Liu, Shuqin; Chen, Guosheng; Tong, Yexiang; Zhu, Fang; Ouyang, Gangfeng

2017-01-18

Nanostructured materials have great potential for solid phase microextraction (SPME) on account of their tiny size, distinct architectures and superior physical and chemical properties. Herein, a core-shell TiO 2 @C fiber for SPME was successfully fabricated by the simple hydrothermal reaction of a titanium wire and subsequent amorphous carbon coating. The readily hydrothermal procedure afforded in situ synthesis of TiO 2 nanowires on a titanium wire and provided a desirable substrate for further coating of amorphous carbon. Benefiting from the much larger surface area of subsequent TiO 2 and good adsorption property of the amorphous carbon coating, the core-shell TiO 2 @C fiber was utilized for the SPME device for the first time and proved to have better performance in extraction of polycyclic aromatic hydrocarbons. In comparison to the polydimethylsiloxane (PDMS) and PDMS/divinylbenzene (DVB) fiber for commercial use, the TiO 2 @C fiber obtained gas chromatography responses 3-8 times higher than those obtained by the commercial 100 μm PDMS and 1-9 times higher than those obtained by the 65 μm PDMS/DVB fiber. Under the optimized extraction conditions, the low detection limits were obtained in the range of 0.4-7.1 ng L -1 with wider linearity in the range of 10-2000 ng L -1 . Moreover, the fiber was successfully used for the determination of polycyclic aromatic hydrocarbons in Pearl River water, which demonstrated the applicability of the core-shell TiO 2 @C fiber.

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

Charnawskas, Joseph C.; Alpert, Peter A.; Lambe, Andrew T.

Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil fuel combustion can acquire a coating of SOA. We investigate SOA–soot biogenic–anthropogenic interactions and their impact on ice nucleation in relation to the particles’ organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without the presence of sulfate or soot particles. Corresponding particle glass transition (T g) and full deliquescence relative humidity (FDRH) were estimated using a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfatemore » mixtures exhibit a core–shell configuration (i.e.a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation, in agreement with respectiveT gand FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid, inducing ice nucleation. Naphthalene SOA coated soot particles acted as ice nuclei above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate renders this even less likely. However, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during pre-industrial times or in pristine areas.« less

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

Charnawskas, Joseph C.; Alpert, Peter A.; Lambe, Andrew

Anthropogenic and biogenic gas emissions contribute to the formation of secondary organic aerosol (SOA). When present, soot particles from fossil-fuel combustion can acquire a coating of SOA. We investigate SOA-soot biogenic-anthropogenic interactions and their impact on ice nucleation in relation to the particles’ organic phase state. SOA particles were generated from the OH oxidation of naphthalene, α-pinene, longifolene, or isoprene, with or without presence of sulfate or soot particles. Corresponding particle glass transition (T g) and full deliquescence relative humidity (FDRH) were estimated by a numerical diffusion model. Longifolene SOA particles are solid-like and all biogenic SOA sulfate mixtures exhibitmore » a core-shell configuration (i.e. a sulfate-rich core coated with SOA). Biogenic SOA with or without sulfate formed ice at conditions expected for homogeneous ice nucleation in agreement with respective T g and FDRH. α-pinene SOA coated soot particles nucleated ice above the homogeneous freezing temperature with soot acting as ice nuclei (IN). At lower temperatures the α-pinene SOA coating can be semisolid inducing ice nucleation. Naphthalene SOA coated soot particles acted as IN above and below the homogeneous freezing limit, which can be explained by the presence of a highly viscous SOA phase. Our results suggest that biogenic SOA does not play a significant role in mixed-phase cloud formation and the presence of sulfate further renders this even less likely. Furthermore, anthropogenic SOA may have an enhancing effect on cloud glaciation under mixed-phase and cirrus cloud conditions compared to biogenic SOA that dominate during preindustrial times or in pristine areas.« less

Mesoporous carbon-zirconium oxide nanocomposite derived from carbonized metal organic framework: A coating for solid-phase microextraction.

PubMed

Saraji, Mohammad; Mehrafza, Narges

2016-08-19

In this paper, a mesoporous carbon-ZrO2 nanocomposite was fabricated on a stainless steel wire for the first time and used as the solid-phase microextraction coating. The fiber was synthesized with the direct carbonization of a Zr-based metal organic framework. With the utilization of the metal organic framework as the precursor, no additional carbon source was used for the synthesis of the mesoporous carbon-ZrO2 nanocomposite coating. The fiber was applied for the determination of BTEX compounds (benzene, toluene, ethylbenzene and m, p-xylenes) in different water samples prior to gas chromatography-flame ionization detection. Such important experimental factors as synthesis time and temperature, salt concentration, equilibrium and extraction time, extraction temperature, desorption time and desorption temperature were studied and optimized. Good linearity in the concentration range of 0.2-200μgL(-1) and detection limits in the range of 0.05-0.56μgL(-1) was achieved for BTEX compounds. The intra- and inter-day relative standard deviations were in the range of 3.5-4.8% and 4.9-6.7%, respectively. The prepared fiber showed high capability for the analysis of BTEX compounds in different water and wastewater samples with good relative recoveries in the range of 93-107%. Copyright © 2016 Elsevier B.V. All rights reserved.

A platinized stainless steel fiber with in-situ coated polyaniline/polypyrrole/graphene oxide nanocomposite sorbent for headspace solid-phase microextraction of aliphatic aldehydes in rice samples.

PubMed

Ghiasvand, Alireza; Nasirian, Afagh; Koonani, Samira; Nouriasl, Kolsoum

2017-12-01

The surface of a stainless steel fiber was made larger, porous and cohesive by platinizing for tight attachment of its coating. Then it was coated by a polyaniline/polypyrrole/graphene oxide (PANI/PP/GO) nanocomposite film using electrochemical polymerization. The prepared PANI/PP/GO fiber was used for headspace solid-phase microextraction (HS-SPME) of linear aliphatic aldehydes in rice samples followed by GC-FID determination. To achieve the highest extraction efficiency, various experimental parameters including extraction time and temperature, matrix modifier and desorption condition were studied. The linear calibration curves were obtained over the range of 0.05-20 μg g -1 (R 2  > 0.99) for C 4 -C 11 aldehydes. The limits of detection were found to be in the range of 0.01-0.04 μg g -1 . RSD values were calculated to be <7.4 and 10.7% for intra- and inter-day, respectively. The superiority of the prepared nanocomposite SPME fiber was established by comparison of its results with those obtained by polydimethylsiloxane, carbowax-divinylbenzene, divinylbenzene-carboxen-polydimethylsiloxane and polyacrylate commercial ones. Finally, the nanocomposite fiber was used to extract and determine linear aliphatic aldehydes in 18 rice samples. Copyright © 2017 John Wiley & Sons, Ltd.

Effect of Binding Components in Complex Sample Matrices on Recovery in Direct Immersion Solid-Phase Microextraction: Friends or Foe?

PubMed

Alam, Md Nazmul; Pawliszyn, Janusz

2018-02-20

The development of matrix compatible coatings for solid-phase microextraction (SPME) has enabled direct extraction of analytes from complex sample matrices. The direct immersion (DI) mode of SPME when utilized in conjunction with such extraction phases facilitates extraction of a wide range of analytes from complex matrices without the incurrence of fouling or coating saturation. In this work, mathematical models and computational simulations were employed to investigate the effect of binding components present in complex samples on the recovery of small molecules varying in logP for extractions carried out using the direct immersion approach. The presented findings corroborate that the studied approach indeed enables the extraction of both polar and nonpolar analytes from complex matrices, provided a suitable sorbent is employed. Further results indicated that, in certain cases, the kinetics of extraction of a given analyte in its free form might be dependent on the desorption kinetics of their bound form from matrix components, which might lower total recoveries of analytes with high affinity for the matrix. However, the binding of analytes to matrix components also enables SPME to extract a balanced quantity of different logP analytes, facilitated by multiphase equilibria, with a single extraction device.

Chitosan-Coated Cinnamon/Oregano-Loaded Solid Lipid Nanoparticles to Augment 5-Fluorouracil Cytotoxicity for Colorectal Cancer: Extract Standardization, Nanoparticle Optimization, and Cytotoxicity Evaluation.

PubMed

Kamel, Kamel M; Khalil, Islam A; Rateb, Mostafa E; Elgendy, Hosieny; Elhawary, Seham

2017-09-13

This study aimed to coat lipid-based nanocarriers with chitosan to encapsulate nutraceuticals, minimize opsonization, and facilitate passive-targeting. Phase one was concerned with standardization according to the World Health Organization. Qualitative analysis using liquid chromatography-high-resolution mass spectrometry (LC-HRMS/MS) investigated the active constituents, especially reported cytotoxic agents. Cinnamaldehyde and rosmarinic acid were selected to be quantified using high-performance liquid chromatography. Phase two was aimed to encapsulate both extracts in solid lipid nanoparticles (core) and chitosan (shell) to gain the advantages of both materials properties. The developed experimental model suggested an optimum formulation with 2% lipid, 2.3% surfactant, and 0.4% chitosan to achieve a particle size of 254.77 nm, polydispersity index of 0.28, zeta potential of +15.26, and entrapment efficiency percentage of 77.3% and 69.1% for cinnamon and oregano, respectively. Phase three was focused on the evaluation of cytotoxic activity unencapsulated/encapsulated cinnamon and oregano extracts with/without 5-fluorouracil on HCT-116 cells. This study confirmed the success of the suggested combination with 5-fluorouracil for treating human colon carcinoma with a low dose leading to decreasing side effects and allowing uninterrupted therapy.

The fate of arsenic in sediments formed at a river confluence affected by acid mine drainage

NASA Astrophysics Data System (ADS)

Guerra, P. A.; Pasten, P. A.; Pizarro, G.; Simonson, K.; Escauriaza, C. R.; Gonzalez, C.; Bonilla, C.

2012-12-01

Fluvial confluences receiving acid mine drainage may play a critical role in a watershed as a suite of interactions between chemistry and hydrodynamics occur, determining the fate of toxic contaminants like arsenic. Solid reactive phases of iron and/or aluminum oxi-hydroxides may form or transform, ranging from iron oxide nanoparticles that aggregate and form floccules that are transported in the suspended load up to gravel and arsenic-rich rock coatings. In order to further understand the role of reactive fluvial confluences, we have studied the mixing between the Caracarani River (flow=170-640 L/s, pH 8, conductivity 1.5 mS/cm, total As<0.1 mg/L and total Fe< 5 mg/L) and the Azufre River (flow=45-245 L/s, pH<2, conductivity > 10 mS/cm, total As>2 mg/L, total Fe=35-125 mg/L), located in the Lluta watershed in northern Chile. This site is an excellent natural laboratory located in a water-scarce area, where the future construction of a dam has prompted the attention of decision makers and scientists interested in weighing the risks derived by the accumulation of arsenic-rich sediments. Suspended sediments (> 0.45 μm), riverbed sediments, and coated rocks were collected upstream and downstream from the confluence. Suspended sediments >0.45 μm and riverbed sediments were analyzed by total reflection x-ray fluorescence for metals, while coated river bed rocks were analyzed by chemical extractions and a semi-quantitative approach through portable x-ray fluorescence. Water from the Caracarani and Azufre rivers were mixed in the laboratory at different ratios and mixing velocities aiming to characterize the effect of the chemical-hydrodynamic environment where arsenic solids were formed at different locations in the confluence. Despite a wide range of iron and arsenic concentrations in the suspended sediments from the field (As=1037 ± 1372 mg/kg, Fe=21.0 ± 24.5 g/kg), we found a rather narrow As/Fe ratio, increasing from 36.5 to 55.2 mgAs/kgFe when the bulk water pH increased from 3 to 6. Sequential extraction analyses suggest that ~80% of As in the solid pahse is strongly sorbed to the sediments, whereas ~15% of As is forming co-precipitated phase. Riverbed sediments (sand and gravel) showed much lower concentrations of Fe and As (17.1 ± 3.0 g/kg and 67.5 ± 53.9 mg/kg, respectively), owing to a dilution from non-reactive phases like quartz from sand. Coated rocks showed concentrations of Fe and As of 34.8 ± 12.5 g/kg and 680 ± 401 mg/kg, respectively, suggesting the coatings are possibly constituted by As-rich particles sequestered from the flow. In the case of the laboratory mixing tests, suspended solids ranged from 10 to 60 mg/L, with higher values at lower mixing ratios or higher pHs. Our findings suggest that the spatial and temporal variability driven by the hydrodynamics of a confluence determine distinct geochemical characteristics of arsenic-rich solid phases, thus playing a role in the fate of reactive contaminants like arsenic in the watershed. Research funded by Fondecyt project 1100943.

Preparation and quantification of the total phenolic products in Citrus fruit using solid-phase extraction coupled with high-performance liquid chromatography with diode array and UV detection.

PubMed

Zeng, Honglian; Liu, Zhenli; Zhao, Siyu; Shu, Yisong; Song, Zhiqian; Wang, Chun; Dong, Yunzhuo; Ning, Zhangchi; He, Dan; Wang, Menglei; Lu, Cheng; Liu, Yuanyan; Lu, Aiping

2016-10-01

Citrus fruit is an important health-promoting food that is rich in dietary phenolic metabolites. Traditional Chinese medicines, such as Zhishi and Zhiqiao, come from young and immature fruits of Citrus cultivars. The preparation of diversified bioactive phenolic products and establishment of the corresponding quality control methodology are challenging and necessary. In the current study, four types of solid-phase extraction sorbents for the enrichment and clean-up of the phenolic matrix were evaluated. A solid-phase extraction column coated with Strata-X was finally used in the procedure. Twenty phenolic compounds were selected to evaluate the extraction performances of the sorbents using high-performance liquid chromatography analysis. Under the optimized conditions, good linearities were obtained with R 2 more than 0.9996 for all analytes with LODs of 0.04-1.012 μg/g. Intra- and interday relative standard deviation values were less than 3%, and the recovery was equal to or higher than 90.02%. Compared to non-solid-phase extraction process, the content of total phenolic products was elevated 35.55-68.48% with solid-phase extraction. Finally, the developed and validated method was successfully applied to the discrimination of Zhishi samples from different species as well as Zhishi and Zhiqiao samples in different development stages. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Chen, S.-S.; IGE Therapeutics, Inc., Cellular and Cancer Immunology, 6370 Lusk Boulevard, F109, San Diego, CA 92121; Yang Yongmin

GFP-C{kappa} fusion protein was previously shown selectable on ribosome display platform with solid phase antibodies against GFP determinant [Y.-M. Yang, T.J. Barankiewicz, M. He, M. Taussig, S.-S. Chen, Selection of antigenic markers on a GFP-C{kappa} fusion scaffold with high sensitivity by eukaryotic ribosome display, Biochem. Biophys. Res. Commun. 359 (2007) 251-257]. Herein, we show that members of aptameric peptide library constructed within the site 6 and site 8/9 loops of GFP of the ribosome display construct are selectable upon binding to the solid phase IgE antigen. An input of 1.0 {mu}g of the dual site aptameric GFP library exhibiting amore » diversity of 7.5 x 10{sup 11} was transcribed, translated and incubated with solid phase IgE. RT-PCR products were amplified from mRNA of the aptamer-ribosome-mRNA (ARM) complex captured on the solid phase IgE. Clones of aptameric GFP were prepared from RT-PCR product of ARM complex following repetitive selection. Recombinant aptameric GFP proteins from the selected clones bind IgE coated on the 96-well plate, and the binding was abrogated by incubation with soluble human IgE but not human IgG. Selected aptameric GFP proteins also exhibit binding to three different sources of human IgE (IgE PS, BED, and JW8) but not irrelevant proteins. These observations indicate that appropriately selected aptameric GFP on a solid phase ligand by ribosome display may serve as an affinity reagent for blocking reactivity of a biological ligand.« less

Fumed metallic oxides and conventional pigments for glossy inkjet paper

NASA Astrophysics Data System (ADS)

Lee, Hyunkook

Product development activity in the area of inkjet printing papers has accelerated greatly to meet the rapidly growing market for inkjet papers. Advancements in inkjet printing technology have also placed new demands on the paper substrate due to faster printing rates, greater resolution through increased drop volumes, and colorants added to the ink. To meet these requirements, papermakers are turning to pigmented size press formulations or pigmented coating systems. For inkjet coating applications, both the internal porosity of the pigment particles as well as the packing porosity of the coating affect print quality and dry time. Pores between the pigment particles allow for rapid diffusion of ink fluids into the coating structure, while also providing capacity for ink fluid uptake. Past research has shown the presence of coating cracks to increase the microroughness of the papers, consequently reducing the gloss of the silica/polyvinyl alcohol based coating colors. Coating cracks were not observed, at the same level of magnification, in the scanning electron microscopy images of alumina/polyvinyl alcohol coated papers. Studies are therefore needed to understand the influence of coating cracking on the microroughening of silica/polyvinyl alcohol based coatings and consequences to coating and ink gloss. Since micro roughening is known to be linked to shrinkage of the coating layer, studies are needed to determine if composite pigments can be formulated, which would enable the coating solids of the formulations to be increased to minimize the shrinkage of coating layer during drying. Coating solids greater than 55% solids are needed to reduce the difference between application solids and the coating's immobilization solids point in order to reduce shrinkage. The aim of this research was to address the above mentioned needed studies. Studies were performed to understand the influence of particle packing on gloss and ink jet print quality. Composite pigment structures were built using well-characterized pigments to determine the influence of particle size and particle size distribution on coating application solids, coatings immobilization solids on coating gloss and print attributes. This research consists of five articles which have all been accepted for publication: (1) Influence of Pigment Particles on the Gloss and Printability of Inkjet Coated Papers, (2) Influence of Silica and Alumina Oxide Pigments on Coating Structure and Print Quality of Inkjet Papers, (3) Production of a Single Coated Glossy Inkjet Paper Using Conventional Coating and Calendering Methods, (4) Influence of Pigment Particle Size and Packing Volume on the Printability of Glossy Inkjet Paper Coatings-Part I, and (5) Influence of Pigment Selection on Printability of Glossy Inkjet Paper Coatings-Part II.

Adhesion force interactions between cyclopentane hydrate and physically and chemically modified surfaces.

PubMed

Aman, Zachary M; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

2014-12-07

Interfacial interactions between liquid-solid and solid-solid phases/surfaces are of fundamental importance to the formation of hydrate deposits in oil and gas pipelines. This work establishes the effect of five categories of physical and chemical modification to steel on clathrate hydrate adhesive force: oleamide, graphite, citric acid ester, nonanedithiol, and Rain-X anti-wetting agent. Hydrate adhesive forces were measured using a micromechanical force apparatus, under both dry and water-wet surface conditions. The results show that the graphite coating reduced hydrate-steel adhesion force by 79%, due to an increase in the water wetting angle from 42 ± 8° to 154 ± 7°. Two chemical surface coatings (nonanedithiol and the citric acid ester) induced rapid hydrate growth in the hydrate particles; nonanedithiol increased hydrate adhesive force by 49% from the baseline, while the citric acid ester coating reduced hydrate adhesion force by 98%. This result suggests that crystal growth may enable a strong adhesive pathway between hydrate and other crystalline structures, however this effect may be negated in cases where water-hydrocarbon interfacial tension is minimised. When a liquid water droplet was placed on the modified steel surfaces, the graphite and citric acid ester became less effective at reducing adhesive force. In pipelines containing a free water phase wetting the steel surface, chemical or physical surface modifications alone may be insufficient to eliminate hydrate deposition risk. In further tests, the citric acid ester reduced hydrate cohesive forces by 50%, suggesting mild activity as a hybrid anti-agglomerant suppressing both hydrate deposition and particle agglomeration. These results demonstrate a new capability to develop polyfunctional surfactants, which simultaneously limit the capability for hydrate particles to aggregate and deposit on the pipeline wall.

Method and device for producing and delivering an aerosol for remote sealing and coating

DOEpatents

Modera, M.P.; Carrie, F.R.

1996-06-04

The invention is a method and device for sealing leaks remotely by means of injecting a previously prepared aerosol into the enclosure being sealed. Specifically the invention is a method and device for preparing, transporting, and depositing and solid phase aerosol to the interior surface of the enclosure. 1 fig.

Section 2: Phase transformation studies in mechanically alloyed Fe-Nz and Fe-Zn-Si intermetallics

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

Jordan, A.; Uwakweh, O.N.C.; Maziasz, P.J.

1997-04-01

The initial stage of this study, which was completed in FY 1995, entailed an extensive analysis characterizing the structural evolution of the Fe-Zn intermetallic system. The primary interest in these Fe-Zn phases stems from the fact that they form an excellent coating for the corrosion protection of steel (i.e., automobile body panels). The Fe-Zn coating generally forms up to four intermetallic phases depending on the particular industrial application used, (i.e., galvanization, galvannealing, etc.). Since the different coating applications are non-equilibrium in nature, it becomes necessary to employ a non-equilibrium method for producing homogeneous alloys in the solid-state to reflect themore » structural changes occurring in a true coating. This was accomplished through the use of a high energy/non-equilibrium technique known as ball-milling which allowed the authors to monitor the evolution process of the alloys as they transformed from a metastable to stable equilibrium state. In FY 1996, this study was expanded to evaluate the presence of Si in the Fe-Zn system and its influence in the overall coating. The addition of silicon in steel gives rise to an increased coating. However, the mechanisms leading to the coating anomaly are still not fully understood. For this reason, mechanical alloying through ball-milling of pure elemental powders was used to study the structural changes occurring in the sandelin region (i.e., 0.12 wt % Si). Through the identification of invariant reactions (i.e., eutectic, etc.) the authors were able to explore the sandelin phenomenon and also determine the various fields or boundaries associated with the Fe-Zn-Si ternary system.« less

Electro-assisted solid-phase microextraction based on poly(3,4-ethylenedioxythiophen) combined with GC for the quantification of tricyclic antidepressants.

PubMed

Davarani, Saied Saeed Hosseiny; Nojavan, Saeed; Asadi, Roghayeh; Banitaba, Mohammad Hossein

2013-07-01

In this study, a platinum wire coated with poly(3,4-ethylenedioxythiophen) was used as an electro-assisted solid-phase microextraction fiber for the quantification of tricyclic antidepressant drugs in biological samples by coupling to GC employing a flame ionization detector. In this study, an electric field increased the extraction rate and recovery. The fiber used as a solid phase was synthesized by the electropolymerization of 3,4-ethylenedioxythiophen monomers onto a platinum wire. The ability of this fiber to extract imipramine, desipramine, and clomipramine by using the electro-assisted solid-phase microextraction technique was evaluated. The effect of various parameters that influence the extraction efficiency, which include solution temperature, extraction time, stirring rate, ionic strength, time and temperature of desorption, and thickness of the fiber, was optimized. Under optimized conditions, the linear ranges and regression coefficients of calibration curves were in the range of 0.5-250 and 0.990-0.998 ng/mL, respectively. Detection limits were in the range of 0.15-0.45 ng/mL. Finally, this method was applied to the determination of drugs in urine and wastewater samples and recoveries were 4.8-108.9%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identification of unwanted photoproducts of cosmetic preservatives in personal care products under ultraviolet-light using solid-phase microextraction and micro-matrix solid-phase dispersion.

PubMed

Alvarez-Rivera, Gerardo; Llompart, Maria; Garcia-Jares, Carmen; Lores, Marta

2015-04-17

The photochemical transformation of widely used cosmetic preservatives including benzoates, parabens, BHA, BHT and triclosan has been investigated in this work applying an innovative double-approach strategy: identification of transformation products in aqueous photodegradation experiments (UV-light, 254nm), followed by targeted screening analysis of such photoproducts in UV-irradiated cosmetic samples. Solid-phase microextraction (SPME) was applied, using different fiber coatings, in order to widen the range of detectable photoproducts in water, whereas UV-irradiated personal care products (PCPs) containing the target preservatives were extracted by micro-matrix solid-phase dispersion (micro-MSPD). Both SPME and micro-MSPD-based methodologies were successfully optimized and validated. Degradation kinetics of parent species, and photoformation of their transformation by-products were monitored by gas chromatography coupled to mass spectrometry (GC-MS). Thirty nine photoproducts were detected in aqueous photodegradation experiments, being tentatively identified based on their mass spectra. Transformation pathways between structurally related by-products, consistent with their kinetic behavior were postulated. The photoformation of unexpected photoproducts such as 2- and 4-hydroxybenzophenones, and 2,8-dichlorodibenzo-p-dioxin in PCPs are reported in this work for the first time. Copyright © 2015 Elsevier B.V. All rights reserved.

Fullerene C60 and graphene photosensibiles for photodynamic virus inactivation

NASA Astrophysics Data System (ADS)

Belousova, I.; Hvorostovsky, A.; Kiselev, V.; Zarubaev, V.; Kiselev, O.; Piotrovsky, L.; Anfimov, P.; Krisko, T.; Muraviova, T.; Rylkov, V.; Starodubzev, A.; Sirotkin, A.; Grishkanich, A.; Kudashev, I.; Kancer, A.; Kustikova, M.; Bykovskaya, E.; Mayurova, A.; Stupnikov, A.; Ruzankina, J.; Afanasyev, M.; Lukyanov, N.; Redka, D.; Paklinov, N.

2018-02-01

A solid-phase photosensitizer based on aggregated C60 fullerene and graphene oxide for photodynamic inactivation of pathogens in biological fluids was studied. The most promising technologies of inactivation include the photodynamic effect, which consists in the inactivation of infectious agents by active oxygen forms (including singlet oxygen), formed when light is activated by the photosensitizer introduced into the plasma. Research shows features of solid-phase systems based on graphene and fullerene C60 oxide, which is a combination of an effective inactivating pathogens (for example, influenza viruses) reactive oxygen species formed upon irradiation of the photosensitizer in aqueous and biological fluids, a high photostability fullerene coatings and the possibility of full recovery photosensitizer from the biological environment after the photodynamic action.

Laser surface alloying of FeCoCrAlNi high-entropy alloy on 304 stainless steel to enhance corrosion and cavitation erosion resistance

NASA Astrophysics Data System (ADS)

Zhang, S.; Wu, C. L.; Zhang, C. H.; Guan, M.; Tan, J. Z.

2016-10-01

FeCoCrAlNi high-entropy alloy coating was synthesized with premixed high-purity Co, Cr, Al and Ni powders on 304 stainless steel by laser surface alloying, aiming at improving corrosion and cavitation erosion resistance. Phase constituents, microstructure and microhardness were investigated using XRD, SEM, and microhardness tester, respectively. The cavitation erosion and electrochemical corrosion behavior of FeCoCrAlNi coating in 3.5% NaCl solution were also evaluated using an ultrasonic vibrator and potentiodynamic polarization measurement. Experimental results showed that with appropriate laser processing parameters, FeCoCrAlNi coating with good metallurgical bonding to the substrate could be achieved. FeCoCrAlNi coating was composed of a single BCC solid solution. The formation of simple solid solutions in HEAs was the combined effect of mixing entropy (ΔSmix), mixing enthalpy (ΔHmix), atom-size difference (δ) and valence electron concentration (VEC), and the effect of ΔSmix was much larger than that of the other factors. The microhardness of the FeCoCrAlNi coating was ~3 times that of the 304 stainless steel. Both the corrosion and cavitation erosion resistance of the coating were improved. The cavitation erosion resistance for FeCoCrAlNi HEA coating was ~7.6 times that of 304 stainless steel. The corrosion resistance was also improved as reflected by a reduction in the current density of one order of magnitude as compared with 304 stainless steel.

Nanostructured multielement (TiHfZrNbVTa)N coatings before and after implantation of N+ ions (1018 cm-2): Their structure and mechanical properties

NASA Astrophysics Data System (ADS)

Pogrebnjak, A. D.; Bondar, O. V.; Borba, S. O.; Abadias, G.; Konarski, P.; Plotnikov, S. V.; Beresnev, V. M.; Kassenova, L. G.; Drodziel, P.

2016-10-01

Multielement high entropy alloy (HEA) nitride (TiHfZrNbVTa)N coatings were deposited by vacuum arc and their structural and mechanical stability after implantation of high doses of N+ ions, 1018 cm-2, were investigated. The crystal structure and phase composition were characterized by X-ray diffraction (XRD) and Transmission Electron Microscopy, while depth-resolved nanoindentation tests were used to determine the evolution of hardness and elastic modulus along the implantation depth. XRD patterns show that coatings exhibit a main phase with fcc structure, which preferred orientation varies from (1 1 1) to (2 0 0), depending on the deposition conditions. First-principles calculations reveal that the presence of Nb atoms could favor the formation of solid solution with fcc structure in multielement HEA nitride. TEM results showed that amorphous and nanostructured phases were formed in the implanted coating sub-surface layer (∼100 nm depth). Concentration of nitrogen reached 90 at% in the near-surface layer after implantation, and decreased at higher depth. Nanohardness of the as-deposited coatings varied from 27 to 38 GPa depending on the deposition conditions. Ion implantation led to a significant decrease of the nanohardness to 12 GPa in the implanted region, while it reaches 24 GPa at larger depths. However, the H/E ratio is ⩾0.1 in the sub-surface layer due to N+ implantation, which is expected to have beneficial effect on the wear properties.

Gas/solid carbon branching ratios in surface-mediated reactions and the incorporation of carbonaceous material into planetesimals

PubMed Central

Nuth, Joseph A.; Johnson, Natasha M.; Ferguson, Frank T.; Carayon, Alicia

2018-01-01

We report the ratio of the initial carbon available as CO that forms gas-phase compounds compared to the fraction that deposits as a carbonaceous solid (the gas/solid branching ratio) as a function of time and temperature for iron, magnetite, and amorphous iron silicate smoke catalysts during surface-mediated reactions in an excess of hydrogen and in the presence of N2. This fraction varies from more than 99% for an amorphous iron silicate smoke at 673 K to less than 40% for a magnetite catalyst at 873 K. The CO not converted into solids primarily forms methane, ethane, water, and CO2, as well as a very wide range of organic molecules at very low concentration. Carbon deposits do not form continuous coatings on the catalytic surfaces, but instead form extremely high surface area per unit volume “filamentous” structures. While these structures will likely form more slowly but over much longer times in protostellar nebulae than in our experiments due to the much lower partial pressure of CO, such fluffy coatings on the surfaces of chondrules or calcium aluminum inclusions could promote grain–grain sticking during low-velocity collisions. PMID:29563766

Gas/Solid Carbon Branching Ratios in Surface Mediated Reactions and the Incorporation of Carbonaceous Material into Planetesimals

NASA Technical Reports Server (NTRS)

Nuth, Joseph A.; Johnson, Natasha M.; Ferguson, Frank T.; Carayon, Alicia

2016-01-01

We report the ratio of the initial carbon available as CO that forms gas-phase compounds compared to the fraction that deposits as a carbonaceous solid (the gas solid branching ratio) as a function of time and temperature for iron, magnetite, and amorphous iron silicate smoke catalysts during surface-mediated reactions in an excess of hydrogen and in the presence of N2. This fraction varies from more than 99 for an amorphous iron silicate smoke at 673 K to less than 40% for a magnetite catalyst at 873 K. The CO not converted into solids primarily forms methane, ethane, water, and CO2, as well as a very wide range of organic molecules at very low concentration. Carbon deposits do not form continuous coatings on the catalytic surfaces, but instead form extremely high surface area per unit volume filamentous structures. While these structures will likely form more slowly but over much longer times in protostellar nebulae than in our experiments due to the much lower partial pressure of CO, such fluffy coatings on the surfaces of chondrules or calcium aluminum inclusions could promote grain-grain sticking during low-velocity collisions.

Computational design and fabrication of core-shell magnetic molecularly imprinted polymer for dispersive micro-solid-phase extraction coupled with high-performance liquid chromatography for the determination of rhodamine 6G.

PubMed

Xie, Jin; Xie, Jie; Deng, Jian; Fang, Xiangfang; Zhao, Haiqing; Qian, Duo; Wang, Hongjuan

2016-06-01

A novel core-shell magnetic nano-adsorbent with surface molecularly imprinted polymer coating was fabricated and then applied to dispersive micro-solid-phase extraction followed by determination of rhodamine 6G using high-performance liquid chromatography. The molecularly imprinted polymer coating was prepared by copolymerization of dopamine and m-aminophenylboronic acid (functional monomers), in the presence of rhodamine 6G (template). The selection of the suitable functional monomers was based on the interaction between different monomers and the template using the density functional theory. The ratios of the monomers to template were further optimized by an OA9 (3(4) ) orthogonal array design. The binding performances of the adsorbent were evaluated by static, kinetic, and selective adsorption experiments. The results reveal that the adsorbent possesses remarkable affinity and binding specificity for rhodamine 6G because of the enhanced Lewis acid-base interaction between the B(Ш) embedded in the imprinted cavities and the template. The nano-adsorbent was successfully applied to dispersive micro-solid-phase extraction coupled to high-performance liquid chromatography for the trace determination of rhodamine 6G in samples with a detection limit of 2.7 nmol/L. Spiked recoveries ranged from 93.0-99.1, 89.5-92.7, and 86.9-105% in river water, matrimony vine and paprika samples, respectively, with relative standard deviations of less than 4.3%. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A silica fiber coated with a ZnO-graphene oxide nanocomposite with high specific surface for use in solid phase microextraction of the antiepileptic drugs diazepam and oxazepam.

PubMed

Alizadeh, Reza; Salami, Maryam; Seidi, Shahram

2018-06-02

A novel ZnO-graphene oxide nanocomposite was prepared and is shown to be a viable coating on fused silica fibers for use in solid phase microextraction (SPME) of diazepam and oxazepam from urine, this followed by thermal desorption and gas chromatographic quantitation using a flame ionization detector. A central composite design was used to optimize extraction time, salt percentage, sample pH and desorption time. Limits of detection are 0.5 μg·L -1 for diazepam and 1.0 μg·L -1 for oxazepam. Repeatability and reproducibility for one fiber (n = 4), expressed as the relative standard deviation at a concentration of 50 μg·L -1 , are 8.3 and 11.3% for diazepam, and 6.7 and 10.1% for oxazepam. The fiber-to-fiber reproducibility is <17.6%. The calibration plots are linear in the 5.0-1000 μg·L -1 diazepam concentration range, and from 1.0-1000 μg·L -1 in case of oxazepam. The fiber for SPME has high chemical and thermal stability (even at 280 °C) after 50 extractions, and does not suffer from a reduction in the sorption capacity. Graphical abstract A hydrothermal method was introduced for preparation of ZnO- GO nano composite on a fused silica fiber as solid phase microextraction with high mechanical, chemical stability and long service life.

Coated armor system and process for making the same

DOEpatents

Chu, Henry S.; Lillo, Thomas M.; McHugh, Kevin M.

2010-11-23

An armor system and method involves providing a core material and a stream of atomized coating material that comprises a liquid fraction and a solid fraction. An initial layer is deposited on the core material by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is less than the liquid fraction of the stream of atomized coating material on a weight basis. An outer layer is then deposited on the initial layer by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is greater than the liquid fraction of the stream of atomized coating material on a weight basis.

Armor systems including coated core materials

DOEpatents

Chu, Henry S [Idaho Falls, ID; Lillo, Thomas M [Idaho Falls, ID; McHugh, Kevin M [Idaho Falls, ID

2012-07-31

An armor system and method involves providing a core material and a stream of atomized coating material that comprises a liquid fraction and a solid fraction. An initial layer is deposited on the core material by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is less than the liquid fraction of the stream of atomized coating material on a weight basis. An outer layer is then deposited on the initial layer by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is greater than the liquid fraction of the stream of atomized coating material on a weight basis.

Armor systems including coated core materials

DOEpatents

Chu, Henry S; Lillo, Thomas M; McHugh, Kevin M

2013-10-08

An armor system and method involves providing a core material and a stream of atomized coating material that comprises a liquid fraction and a solid fraction. An initial layer is deposited on the core material by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is less than the liquid fraction of the stream of atomized coating material on a weight basis. An outer layer is then deposited on the initial layer by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is greater than the liquid fraction of the stream of atomized coating material on a weight basis.

Liquid spreading on ceramic-coated carbon nanotube films and patterned microstructures

NASA Astrophysics Data System (ADS)

Zhao, Hangbo; Hart, A. John

2015-11-01

We study the capillary-driven liquid spreading behavior on films and microstructures of ceramic-coated vertically aligned carbon nanotubes (CNTs) fabricated on quartz substrates. The nanoscale porosity and micro-scale dimensions of the CNT structures, which can be precisely varied by the fabrication process, enable quantitative measurements that can be related to analytical models of the spreading behavior. Moreover, the conformal alumina coating by atomic layer deposition (ALD) prevents capillary-induced deformation of the CNTs upon meniscus recession, which has complicated previous studies of this topic. Washburn-like liquid spreading behavior is observed on non-patterned CNT surfaces, and is explained using a scaling model based on the balance of capillary driving force and the viscous drag force. Using these insights, we design patterned surfaces with controllable spreading rates and study the contact line pinning-depinning behavior. The nanoscale porosity, controllable surface chemistry, and mechanical stability of coated CNTs provide significantly enhanced liquid-solid interfacial area compared to solid microstructures. As a result, these surface designs may be useful for applications such as phase-change heat transfer and electrochemical energy storage. Funding for this project is provided by the National Institutes of Health and the MIT Center for Clean Water and Clean Energy supported by the King Fahd University of Petroleum and Minerals.

Vapor Phase Alkyne Coating of Pharmaceutical Excipients: Discrimination Enhancement of Raman Chemical Imaging for Tablets.

PubMed

Yamashita, Mayumi; Sasaki, Hiroaki; Moriyama, Kei

2015-12-01

Raman chemical imaging has become a powerful analytical tool to investigate the crystallographic characteristics of pharmaceutical ingredients in tablet. However, it is often difficult to discriminate some pharmaceutical excipients from each other by Raman spectrum because of broad and overlapping signals, limiting their detailed assessments. To overcome this difficulty, we developed a vapor phase coating method of excipients by an alkyne, which exhibits a distinctive Raman signal in the range of 2100-2300 cm(-1) . We found that the combination of two volatile reagents, propargyl bromide and triethylamine, formed a thin and nonvolatile coating on the excipient and observed the Raman signal of the alkyne at the surface. We prepared alkyne-coated cellulose by this method and formed a tablet. The Raman chemical imaging of the tablet cross-section using the alkyne peak area intensity of 2120 cm(-1) as the index showed a much clearer particle image of cellulose than using the peak area intensity of 1370 cm(-1) , which originated from the cellulose itself. Our method provides an innovative technique to analyze the solid-state characteristics of pharmaceutical excipients in tablets. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Water-mediated solid-state transformation of a polymorphic drug during aqueous-based drug-layer coating of pellets.

PubMed

Lust, Andres; Lakio, Satu; Vintsevits, Julia; Kozlova, Jekaterina; Veski, Peep; Heinämäki, Jyrki; Kogermann, Karin

2013-11-01

During aqueous drug-layer coating, drug substance(s) are exposed to water and elevated temperatures which can lead to water-mediated process induced transformations (PITs). The effects of aqueous drug-layer coating of pellets (Cellets(®)) on the anhydrous piroxicam, PRX, were investigated in the miniaturized coating equipment and with free films. Hydroxypropyl methylcellulose (HPMC) was used as a carrier coating polymer. Free films were prepared by using an in-house small-scale rotating plate system equipped with an atomization air nozzle. Raman spectroscopy, X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to characterize the solid-state properties and surface morphology of the pellets and free films. The results showed that anhydrous PRX form I (AH) and monohydrate (MH) were stable during drug-layer coating, but amorphous PRX in solid dispersion (SD) crystallized as MH already after 10 min of coating. Furthermore, the increase in a dissolution rate was achieved from the drug-layer coated inert pellets compared to powder forms. In conclusion, water-mediated solid-state PITs of amorphous PRX is evident during aqueous-based drug-layer coating of pellets, and solid-state change can be verified using Raman spectroscopy. Copyright © 2013 Elsevier B.V. All rights reserved.

Electrochemical preparation of composite polyaniline coating and its application in the determination of bisphenol A, 4-n-nonylphenol, 4-tert-octylphenol using direct solid phase microextraction coupled with high performance liquid chromatography.

PubMed

Huang, Minjia; Jiang, Guibin; Cai, Yaqi

2005-11-01

For SPME-HPLC, metal wires with better mechanical strength are preferred over the fused silica fibers. In this article, a novel composite polyaniline (CPANI) doped with PEG and polydimethylsiloxane coating (CPANI fiber) was prepared on a stainless steel wire by a three-electrode system: the fiber was used as the work electrode, a calomel electrode and a platinum electrode were used as the reference and the counter electrodes, respectively. To evaluate the new CPANI coating, the coating was used to extract three kinds of phenols (bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol) in water samples by direct-SPME mode and then desorbed in commercial SPME-HPLC interface to separation. The extraction procedure was also optimized. Five real water samples were investigated. Good recoveries were gained when environmental samples were analyzed.

Thermochemistry of Silicates

NASA Technical Reports Server (NTRS)

Costa, Gustavo; Jacobson, Nathan

2015-01-01

The thermodynamic properties of vapor and condensed phases of silicates are crucial in many fields of science. These quantities address fundamental questions on the formation, stability, transformation, and physical properties of silicate minerals and silicate coating compositions. Here the thermodynamic activities of silica and other species in solid solution have been measured by the analysis of the corresponding high temperature vapors using Knudsen Effusion Mass Spectrometry (KEMS). In first set of experiments KEMS has been used to examine the volatility sequence of species (Fe, SiO, Mg, O2 and O) present in the vapor phase during heating of fosterite-rich olivine (Fo93Fa7) up to 2400 C and to measure the Fe, SiO and Mg activities in its solid solution. The data of fosterite-rich olivine are essential for thermochemical equilibrium models to predict the atmospheric and surface composition of hot, rocky exoplanets (Lava Planets). In the second set of experiments the measured thermodynamic activities of the silica in Y2O3-SiO2 and Yb2O3-SiO2 systems are used to assess their reactivity and degradation recession as environmental barrier coatings (EBCs) in combustion environments (e.g. non-moveable parts of gas turbine engine).

Nanostructured copper-coated solid-phase microextraction fiber for gas chromatographic analysis of dibutyl phthalate and diethylhexyl phthalate environmental estrogens.

PubMed

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

2015-01-01

A novel nanostructured copper-based solid-phase microextraction fiber was developed and applied for determining the two most common types of phthalate environmental estrogens (dibutyl phthalate and diethylhexyl phthalate) in aqueous samples, coupled to gas chromatography with flame ionization detection. The copper film was coated onto a stainless-steel wire via an electroless plating process, which involved a surface activation process to improve the surface properties of the fiber. Several parameters affecting extraction efficiency such as extraction time, extraction temperature, ionic strength, desorption temperature, and desorption time were optimized by a factor-by-factor procedure to obtain the highest extraction efficiency. The as-established method showed wide linear ranges (0.05-250 μg/L). Precision of single fiber repeatability was <7.0%, and fiber-to-fiber repeatability was <10%. Limits of detection were 0.01 μg/L. The proposed method exhibited better or comparable extraction performance compared with commercial and other lab-made fibers, and excellent thermal stability and durability. The proposed method was applied successfully for the determination of model analytes in plastic soaking water. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dispersive solid-phase extraction for the determination of trace organochlorine pesticides in apple juices using reduced graphene oxide coated with ZnO nanocomposites as sorbent.

PubMed

Sun, Ting; Sun, Hefeng; Zhao, Feng

2017-09-01

In this work, reduced graphene oxide coated with ZnO nanocomposites was used as an efficient sorbent of dispersive solid-phase extraction and successfully applied for the extraction of organochlorine pesticides from apple juice followed by gas chromatography with mass spectrometry. Several experimental parameters affecting the extraction efficiencies, including the amount of adsorbent, extraction time, and the pH of the sample solution, as well as the type and volume of eluent solvent, were investigated and optimized. Under the optimal experimental conditions, good linearity existed in the range of 1.0-200.0 ng/mL for all the analytes with the correlation coefficients (R 2 ) ranging from 0.9964 to 0.9994. The limits of detection of the method for the compounds were 0.011-0.053 ng/mL. Good reproducibilities were acquired with relative standard deviations below 8.7% for both intraday and interday precision. The recoveries of the method were in the range of 78.1-105.8% with relative standard deviations of 3.3-6.9%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous determination of cyanogen chloride and cyanogen bromide in treated water at sub-microg/L levels by a new solid-phase microextraction-gas chromatographic-electron-capture detection method.

PubMed

Cancho, B; Ventur, F; Galceran, M

2000-11-03

A headspace solid-phase microextraction (HS-SPME) procedure has been developed and applied for the determination of cyanogen halides in treated water samples at microg/L concentrations. Several SPME coatings were tested, the divinylbenzene-Carboxen-polydimethylsiloxane fiber being the most appropriate coating. GC-electron-capture detection was used for separation and quantitation. Experimental parameters such as sample volume, addition of a salt, extraction time and desorption conditions were studied. The optimized method has an acceptable linearity, good precision, with RSD values <10% for both compounds, and it is sufficiently sensitive to detect ng/L levels. HS-SPME was compared with liquid-liquid microextraction (US Environmental Protection Agency Method 551.1) for the analysis of spiked ultrapure and granular activated carbon filtered water samples. There was good agreement between the results from both methods. Finally, the optimized procedure was applied to determine both compounds at the Barcelona water treatment plant (N.E. Spain). Cyanogen chloride in treated water was <1.0 microg/L and cyanogen bromide ranged from 3.2 to 6.4 microg/L.

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.

Preparation of porous aromatic framework/ionic liquid hybrid composite coated solid-phase microextraction fibers and their application in the determination of organochlorine pesticides combined with GC-ECD detection.

PubMed

Wu, Mingxue; Chen, Gang; Liu, Ping; Zhou, Weihong; Jia, Qiong

2016-01-07

A novel hybrid material incorporating porous aromatic frameworks and an ionic liquid, 1-(triethoxy silyl)propyl-3-aminopropyl imidazole hexafluorophosphate, was prepared as solid-phase microextraction coating and employed for the extraction of organochlorine pesticides. Combining the advantages of porous aromatic frameworks and an ionic liquid, the fiber exhibited a high adsorption capacity for organochlorine pesticides. Under optimized experimental conditions, enhancement factors of 247-1696 were obtained with good linearity in the range of 1-500 μg L(-1). The detection limits and quantification limits were determined to be in the range of 0.11-0.29 μg L(-1) and 0.35-0.93 μg L(-1). The relative standard deviations for six replicates of organochlorine pesticides were in the range of 4.4%-7.2% and 5.7%-10.1% for one fiber and fiber-to-fiber, respectively. By coupling with a gas chromatography-electron capture detector, the novel fiber was successfully used for the determination of organochlorine pesticides in juice and milk samples with recoveries of 76.1%-121.3%.

Carbon coated titanium dioxide nanotubes: synthesis, characterization and potential application as sorbents in dispersive micro solid phase extraction.

PubMed

García-Valverde, M T; Lucena, R; Galán-Cano, F; Cárdenas, S; Valcárcel, M

2014-05-23

In this article, carbon coated titanium dioxide nanotubes (c-TNTs) have been synthesized. The synthesis of the bare TNTs (b-TNTs) using anatase as precursor and their coating with a caramel layer have been performed by simple and cheap hydrothermal processes. The final conversion of the caramel layer in a carbon coating has been accomplished by a thermal treatment (600°C) in an inert (Ar) atmosphere. The c-TNTs have been characterized by different techniques including transmission microscopy, infrared spectroscopy, X-ray powder diffraction, thermogravimetry and Brunauer, Emmett and Teller (BET) adsorption isotherms. The extraction performance of the c-TNTs under a microextraction format has been evaluated and compared with that provided by b-TNTs and multiwalled carbon nanotubes (MWCNTs) using naproxen and ketoprofen as model analytes. c-TNTs provided better results than the other nanoparticles, especially at low acidic pH values. In addition, c-TNTs presented a better dispersibility than MWCNTs, which is very interesting for their use in dispersive micro-solid phase extraction. Finally, a microextraction format, adapted to low sample volumes, has been proposed and applied for the determination of naproxen and ketoprofen in saliva and urine samples by liquid chromatography with UV detection. The results indicate that this approach is promising for the analysis of biological samples. In fact, the recoveries were in the range between 96% and 119% while the precision, expressed as relative standard deviation, was better than 8.5% and 26.3% for urine and saliva, respectively. The detection limits were in the range 34.1-40.8μg/L for saliva samples and 81.1-110μg/L for urine samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Bis(trifluoromethanesulfonyl)imide-based ionic liquids grafted on graphene oxide-coated solid-phase microextraction fiber for extraction and enrichment of polycyclic aromatic hydrocarbons in potatoes and phthalate esters in food-wrap.

PubMed

Hou, Xiudan; Guo, Yong; Liang, Xiaojing; Wang, Xusheng; Wang, Lei; Wang, Licheng; Liu, Xia

2016-06-01

A class of novel, environmental friendly ionic liquids (ILs) were synthesized by on-fiber preparation strategy and modified on graphene oxide (GO)-coated stainless steel wire, which was used as a solid-phase microextraction (SPME) fiber for efficient enrichment of polycyclic aromatic hydrocarbons (PAHs) and phthalate esters (PAEs). Surface characteristic of the ILs and polymeric-ILs (PILs) fibers with the wave-structure were inspected by scanning electron microscope. The successfully synthesis of bis(trifluoromethanesulfonyl)imide (NTf2(-))-based ILs were also characterized by energy dispersive spectrometer analysis. Through the chromatograms of the proposed two ILs (1-aminoethyl-3-methylimidazolium bromide (C2NH2MIm(+)Br(-)), C2NH2MIm(+)NTf2(-)) and two PILs (polymeric 1-vinyl-3-hexylimidazolium bromide (poly(VHIm(+)Br(-))), poly(VHIm(+)NTf2(-)))-GO-coated fibers for the extraction of analytes, NTf2(-)-based PIL demonstrated higher extraction capacity for hydrophobic compounds than other as-prepared ILs. Analytical performances of the proposed fibers were investigated under the optimized extraction and desorption conditions coupled with gas chromatography (GC). Compared with the poly(VHIm(+)Br(-))-GO fiber, the poly(VHIm(+)NTf2(-))-GO SPME fiber brought wider linear ranges for analytes with correlation coefficient in the range of 0.9852-0.9989 and lower limits of detection ranging from 0.015-0.025μgL(-1). The obtained results indicated that the newly prepared PILs-GO coating was a feasible, selective and green microextraction medium, which could be suitable for extraction and determination of PAHs and PAEs in potatoes and food-wrap sample, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Expanding the use of polymeric ionic liquids in headspace solid-phase microextraction: Determination of ultraviolet filters in water samples.

PubMed

Trujillo-Rodríguez, María J; Nan, He; Anderson, Jared L

2018-03-09

Three crosslinked polymeric ionic liquid (PIL) sorbent coatings were used in headspace solid-phase microextraction for the determination of a group of ultraviolet filters. The developed crosslinked PIL-based materials include two polycations and a double confined PIL. The method, in combination with gas chromatography-mass spectrometry, is simple, solvent free, and does not require of any derivatization step. After proper optimization of the methodologies with each developed fiber, the analytical performance was compared with a commercial polyacrylate fiber. A study of the normalized calibration slopes, obtained by dividing the calibration slope of each analyte by the coating volume, revealed that the crosslinked fibers can be used as alternatives to commercial fibers for the determination of the selected group of compounds. In particular, the coating nature of the PIL containing the 1-vinylbenzyl-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide IL as monomer and the 1,12-di(3-vinylbenzylimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide IL as crosslinker is the most suitable for the extraction of the selected compounds despite their coating volume, being 3.6 times lower than the commercial polyacrylate fiber. For this fiber, wide linear ranges, correlation coefficients higher than 0.990, limits of detection ranging from 2.8 ng L -1 to 26 ng L -1 and relative standard deviations ranging from 2.5 to 15% were achieved. Finally, all proposed PIL-based fibers were applied towards the analysis of tap water, pool water and lake water, with the majority of the ultraviolet filters being detected and quantified in the last two types of samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Solid lubricant behavior of MoS2 and WSe2-based nanocomposite coatings

NASA Astrophysics Data System (ADS)

Domínguez-Meister, Santiago; Rojas, Teresa Cristina; Brizuela, Marta; Sánchez-López, Juan Carlos

2017-12-01

Tribological coatings made of MoS2 and WSe2 phases and their corresponding combinations with tungsten carbide (WC) were prepared by non-reactive magnetron sputtering of individual targets of similar composition. A comparative tribological analysis of these multiphase coatings was done in both ambient air (30-40% relative humidity, RH) and dry nitrogen (RH<7%) environments using the same tribometer and testing conditions. A nanostructural study using advanced transmission electron microscopy of the initial coatings and examination of the counterfaces after the friction test using different analytical tools helped to elucidate what governs the tribological behavior for each type of environment. This allowed conclusions to be made about the influence of the coating microstructure and composition on the tribological response. The best performance obtained with a WSex film (specific wear rate of 2 × 10-8 mm3 N-1m-1 and a friction coefficient of 0.03-0.05) was compared with that of the well-established MoS2 lubricant material.

40 CFR 63.4490 - What emission limits must I meet?

Code of Federal Regulations, 2013 CFR

2013-07-01

...) National Emission Standards for Hazardous Air Pollutants for Surface Coating of Plastic Parts and Products... estimate the relative mass of coating solids used from parameters other than coating consumption and mass solids content (e.g., design specifications for the parts or products coated and the number of items...

40 CFR 63.4490 - What emission limits must I meet?

Code of Federal Regulations, 2012 CFR

2012-07-01

...) National Emission Standards for Hazardous Air Pollutants for Surface Coating of Plastic Parts and Products... estimate the relative mass of coating solids used from parameters other than coating consumption and mass solids content (e.g., design specifications for the parts or products coated and the number of items...

40 CFR 63.4490 - What emission limits must I meet?

Code of Federal Regulations, 2014 CFR

2014-07-01

...) National Emission Standards for Hazardous Air Pollutants for Surface Coating of Plastic Parts and Products... estimate the relative mass of coating solids used from parameters other than coating consumption and mass solids content (e.g., design specifications for the parts or products coated and the number of items...

Dependence of particle concentration effect on pH and redox for arsenic removal by FeS-coated sand under anoxic conditions.

PubMed

Han, Young-Soo; Demond, Avery H; Gallegos, Tanya J; Hayes, Kim F

2015-09-01

FeS has been recognized as a good scavenger for arsenic under anoxic conditions. To create a suitable adsorbent for flow-through reactors such as permeable reactive barriers, it has been suggested that this material may be coated onto sand. However, previous work on FeS-coated sand has focused on batch reactors, while flow-through reactors usually have higher solid-solution ratios. To ascertain whether differences in the solid-solution ratio (SSR) are important in this system, batch sorption experiments were conducted as a function of pH using As(III) and FeS-coated sands at various solid-solution ratios. The results showed little variation in the distribution coefficient with SSR at pH 7 and 9. However, at pH 5, the results showed lower values of the distribution coefficient at lower SSRs, the reverse of typically reported SSR effects. Measured pe values showed a dependence on SSR, which, when coupled with chemical modeling of the Fe-As-S-H2O system, suggested a change in the removal mechanism with SSR, from adsorption to a reduced Fe(II) oxyhydroxide phase (represented by Fe2(OH)5) to precipitation as As2S3 or AsS. On the other hand, at pH 7 and 9, arsenite adsorption is the most probable removal mechanism regardless of the pe. Thus, this study identified variations in pH and redox conditions, and the removal mechanisms that these parameters govern, as the reason for the apparent SSR effect. Copyright © 2014 Elsevier Ltd. All rights reserved.

Singlet oxygen generator for a solar powered chemically pumped iodine laser

NASA Technical Reports Server (NTRS)

Busch, G. E.

1984-01-01

The potential of solid phase endoperoxides as a means to produce single-delta oxygen in the gas phase in concentrations useful to chemical oxygen-iodine lasers was investigated. The 1,4 - endoperoxide of ethyl 3- (4-methyl - 1-naphthyl) propanoate was deposited over an indium-oxide layer on a glass plate. Single-delta oxygen was released from the endoperoxide upon heating the organic film by means of an electrical discharge through the conductive indium oxide coating. The evolution of singlet-delta oxygen was determined by measuring the dimol emission signal at 634 nm. Comparison of the measured signal with an analytic model leads to two main conclusions: virtually all the oxygen being evolved is in the singlet-delta state and in the gas phase, and there is no significant quenching other than energy pooling on the time scale of the experiment (approximately 10 msec). The use of solid phase endoperoxide as a singlet-delta oxygen generator for an oxygen-iodine laser appears promising.

Amorphous surface layer versus transient amorphous precursor phase in bone - A case study investigated by solid-state NMR spectroscopy.

PubMed

Von Euw, Stanislas; Ajili, Widad; Chan-Chang, Tsou-Hsi-Camille; Delices, Annette; Laurent, Guillaume; Babonneau, Florence; Nassif, Nadine; Azaïs, Thierry

2017-09-01

The presence of an amorphous surface layer that coats a crystalline core has been proposed for many biominerals, including bone mineral. In parallel, transient amorphous precursor phases have been proposed in various biomineralization processes, including bone biomineralization. Here we propose a methodology to investigate the origin of these amorphous environments taking the bone tissue as a key example. This study relies on the investigation of a bone tissue sample and its comparison with synthetic calcium phosphate samples, including a stoichiometric apatite, an amorphous calcium phosphate sample, and two different biomimetic apatites. To reveal if the amorphous environments in bone originate from an amorphous surface layer or a transient amorphous precursor phase, a combined solid-state nuclear magnetic resonance (NMR) experiment has been used. The latter consists of a double cross polarization 1 H→ 31 P→ 1 H pulse sequence followed by a 1 H magnetization exchange pulse sequence. The presence of an amorphous surface layer has been investigated through the study of the biomimetic apatites; while the presence of a transient amorphous precursor phase in the form of amorphous calcium phosphate particles has been mimicked with the help of a physical mixture of stoichiometric apatite and amorphous calcium phosphate. The NMR results show that the amorphous and the crystalline environments detected in our bone tissue sample belong to the same particle. The presence of an amorphous surface layer that coats the apatitic core of bone apatite particles has been unambiguously confirmed, and it is certain that this amorphous surface layer has strong implication on bone tissue biogenesis and regeneration. Questions still persist on the structural organization of bone and biomimetic apatites. The existing model proposes a core/shell structure, with an amorphous surface layer coating a crystalline bulk. The accuracy of this model is still debated because amorphous calcium phosphate (ACP) environments could also arise from a transient amorphous precursor phase of apatite. Here, we provide an NMR spectroscopy methodology to reveal the origin of these ACP environments in bone mineral or in biomimetic apatite. The 1 H magnetization exchange between protons arising from amorphous and crystalline domains shows unambiguously that an ACP layer coats the apatitic crystalline core of bone et biomimetic apatite platelets. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Determination of Aromatic Amines Using Solid-Phase Microextraction Based on an Ionic Liquid-Mediated Sol–Gel Technique

PubMed Central

Abbasi, Vajihe; Sarafraz-Yazdi, Ali; Amiri, Amirhassan; Vatani, Hossein

2016-01-01

A headspace solid-phase microextraction (HS-SPME) method was developed for isolation of monocyclic aromatic amines from water samples followed by gas chromatography–flame ionization detector (GC–FID). In this work, the effect of the presence of ionic liquid (namely, 1-hexyl-3-methyl-imidazolium hexafluorophosphate [C6MIM][PF6]) was investigated in the sol–gel coating solutions on the morphology and extraction behavior of the resulting hybrid organic–inorganic sol–gel sorbents utilized in SPME. Hydroxy-terminated poly(dimethylsiloxane) (PDMS) was used as the sol–gel active organic component for sol–gel hybrid coatings. Two different coated fibers that were prepared are PDMS and PDMS-IL ([C6MIM][PF6]) fibers. Under the optimal conditions, the method detection limits (S/N = 3) with PDMS-IL were in the range of 0.001–0.1 ng/mL and the limits of quantification (S/N = 10) between 0.005 and 0.5 ng/mL. The relative standard deviations for one fiber (n = 5) were obtained from 3.1 up to 8.5% and between fibers or batch to batch (n = 3) in the range of 5.3–10.1%. The developed method was successfully applied to real water and juice fruits samples while the relative recovery percentages obtained for the spiked water samples at 0.1 ng/mL were from 83.3 to 95.0%. PMID:26759488

Determination of volatile polycyclic aromatic hydrocarbons in waters using headspace solid-phase microextraction with a benzyl-functionalized crosslinked polymeric ionic liquid coating.

PubMed

Merdivan, Melek; Pino, Verónica; Anderson, Jared L

2017-08-01

A benzyl-functionalized crosslinked polymeric ionic liquid (PIL), produced through the co-polymerization of the 1-vinylbenzyl-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide (VBHDIM-NTf 2 ) ionic liquid (IL) monomer and 1,12-di(3-vinylbenzylimidazolium)dodecane bis[(trifluoromethyl)sulfonyl]imide ((DVBIM) 2 C 12- 2NTf 2 ) IL crosslinker, was successfully used as a sorbent coating in headspace solid-phase microextraction (SPME) coupled to gas chromatography (GC) with flame-ionization detection (FID) to determine seven volatile polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. Optimum extraction conditions for the PAHs when using the novel sorbent include an extraction temperature of 50°C, an ionic strength content adjusted with 30% (w/v) NaCl in the aqueous sample, and an extraction time of 60 min. The extraction performance of the crosslinked PIL fiber was compared to the SPME commercial coating polydimethylsiloxane fiber. The calibration ranges of the studied PAHs were linear in the range of 0.02-20 µg L -1 for the crosslinked PIL fiber. The accuracy of the proposed method was demonstrated by examining the spiked recoveries of seven PAHs which produced values ranging from 67.2% to 130% (for river- and seawater samples), and precision values lower than 9.4% for a spiked level of 1 µg L -1 , and detection limits between 0.01 and 0.04 µg L -1 , which supports the sensitivity of the method using GC-FID.

An etched stainless steel wire/ionic liquid-solid phase microextraction technique for the determination of alkylphenols in river water.

PubMed

Cui, Meiyu; Qiu, Jinxue; Li, Zhenghua; He, Miao; Jin, Mingshi; Kim, Jiman; Quinto, Maurizio; Li, Donghao

2015-01-01

In this study, a stainless steel wire/ionic liquid-solid phase microextraction technique was developed for the direct extraction of APs from water samples. Some parameters were optimised, such as selection of the substrate and ILs, extraction time, extraction temperature, stirring rate and sample pH, etc. The experimental data demonstrated that the etched stainless steel wire was a suitable substrate for IL-coated SPME. The coating was prepared by directly depositing the ILs onto the surface of the etched stainless steel wire, which exhibited a porous structure and a high surface area. The [C8MIM][PF6] IL exhibited maximum efficiency with an extraction time of 30 min, and the aqueous sample was maintained at 40 °C and adjusted to pH 2 under stirring conditions. The enrichment factor of the IL coating for the four APs ranged from 1382 to 4779, the detection limits (LOD, S/N=3) of the four APs ranged from 0.01 to 0.04 ng mL(-1) and the RSD values for purified water spiked with APs ranged from 4.0 to 11.8% (n=3). The calibration graphs were linear in the concentration range from 0.5 to 200 ng mL(-1) (R(2)>0.9569). The optimised method was successfully applied for the analysis of real water samples, and the method was suitable for the extraction of APs from water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Multiresidue analysis of oestrogenic compounds in cow, goat, sheep and human milk using core-shell polydopamine coated magnetic nanoparticles as extraction sorbent in micro-dispersive solid-phase extraction followed by ultra-high-performance liquid chromatography tandem mass spectrometry.

PubMed

Socas-Rodríguez, Bárbara; Hernández-Borges, Javier; Herrera-Herrera, Antonio V; Rodríguez-Delgado, Miguel Ángel

2018-03-01

In this work, the suitability of Fe 3 O 4 nanoparticles coated with polydopamine was evaluated as sorbent for the extraction of a group of 21 compounds with oestrogenic activity including seven phytoestrogens, six mycotoxins as well as four synthetic and four natural oestrogens from different types of milk, including sheep milk, in which the evaluation of oestrogenic compounds have never been developed before. Extraction was carried out using magnetic micro-dispersive solid-phase extraction after a previous deproteinisation step. Separation, determination and quantification of the target analytes were achieved by ultra-high-performance liquid chromatography coupled to triple quadrupole-tandem mass spectrometry. The methodology was validated for five milk samples using 17β-estradiol-2,4,16,16,17-d 5 as internal standard for natural and synthetic oestrogens, β-zearalanol-10,10,11,12,12-d 5 for mycotoxins and prunetin for phytoestrogens. Recovery values ranged from 70 to 120% for the five types of matrices with relative standard deviation values lower than 18%. Limits of quantification of the method were in the range 0.55-11.8 μg L -1 for all samples. Graphical abstract General scheme of the multiresidue analysis of oestrogenic compounds in milk using core-shell polydopamine coated magnetic nanoparticles as extraction sorbent in μ-dSPE.

Microstructural Evolution of AlCoCrFeNiSi High-Entropy Alloy Powder during Mechanical Alloying and Its Coating Performance

PubMed Central

Fu, Ming; Xiong, Wei

2018-01-01

High-entropy alloys (HEAs) are promising structural materials due to their excellent comprehensive performances. The use of mechanically alloyed powders to deposit HEA coatings through atmospheric plasma spraying (APS) is an effective approach that can broaden the application areas of the HEAs. In this paper, a ductility–brittleness AlCoCrFeNiSi system was chosen as an object of study, and the detailed evolution of the surface morphology, particle size distribution, and microstructure of the powder during mechanical alloying was investigated. An AlCoCrFeNiSi HEA coating was deposited using powder milled for 10 h, which can be used as an ideal feedstock for APS. The surface morphology, microstructure, microhardness, and wear behavior of the coating at room temperature were investigated. The results showed that as the milling time increased, the particle size first increased, and then decreased. At the milling time of 10 h, simple body-centered cubic (BCC) and face-centered cubic (FCC) solid solution phases were formed. After spraying, the lamellar structure inside a single particle disappeared. An ordered BCC phase was detected, and the diffraction peaks of the Si element also disappeared, which indicates that phase transformation occurred during plasma spraying. A transmission electron microscopy analysis showed that nanometer crystalline grains with a grain size of about 30 nm existed in the APS coating. For the coating, an average microhardness of 612 ± 41 HV was obtained. Adhesive wear, tribo-oxidation wear, and slight abrasion wear took place during the wear test. The coating showed good wear resistance, with a volume wear rate of 0.38 ± 0.08 × 10−4 mm3·N−1·m−1, which makes it a promising coating for use in abrasive environments. PMID:29473872

Headspace and direct immersion solid phase microextraction procedures for selenite determination in urine, saliva and milk by gas chromatography mass spectrometry.

PubMed

Kapsimali, D C; Zachariadis, G A

2009-10-01

Two solid phase microextraction modes were investigated and compared for their performance on the determination of selenites in various biological liquids like human urine and saliva and various types of milk. Using sodium tetraethylborate (NaBEt(4)) as ethylating reagent, selenites are converted in situ to volatile diethylselenides (DESe) in aqueous medium. The derivative is collected in situ by solid phase microextraction (SPME) using a silica fiber coated with poly(dimethylsiloxane) (PDMS) either from the headspace (HS-SPME) or directly from the liquid phase (LP-SPME) and finally determined by capillary GC/MS. Under optimum conditions of SPME, the GC separation was also optimized. Between the two examined microextraction techniques, direct immersion of the PDMS fiber in the liquid phase was proved less satisfactory. In contrast, the headspace procedure appears to be more efficient. The quantification of selenites was achieved in SIM mode with good analytical performance. A non-fat milk powder certified reference material was analyzed to evaluate the accuracy of the method. The overall precision of the method was ranged between 6.2% and 9.7%. Detection limits achieved were 0.05microgL(-1) for human urine, 0.08microgL(-1) for saliva and 0.03-0.06microgL(-1) in various milk matrices.

A molybdenum disulfide/reduced graphene oxide fiber coating coupled with gas chromatography-mass spectrometry for the saponification-headspace solid-phase microextraction of polychlorinated biphenyls in food.

PubMed

Lv, Fangying; Gan, Ning; Cao, Yuting; Zhou, You; Zuo, Rongjie; Dong, Youren

2017-11-24

In this work, the molybdenum disulfide/reduced graphene oxide (MoS 2 /RGO) composite material was synthesized as a fiber coating to extract seven indicator polychlorinated biphenyls (PCBs; PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180) present in food via a saponification-headspace solid-phase microextraction assay (saponification-HS-SPME). The MoS 2 /RGO coating was prepared and deposited on a stainless steel wire with the help of a silicone sealant and used as an SPME fiber. The alkali solution dissolved the fat and helped in releasing the PCBs present in milk to the headspace for extraction under 100°C. Following desorption in the inlet, the targets were quantified by gas chromatography-mass spectrometry. The effects of sorbent dosage, extraction time, added salts, and stirring rate on the extraction efficiency were investigated. The new coating was able to adsorb a higher amount of analytes, which was about 1.1-2.9 times in comparison with the commercially available SPME fiber (coated with divinylbenzene/carboxen/polydimethylsiloxane). It also showed the highest adsorption capability toward PCBs, which was 1.5-2.7 times that of the prepared RGO modified fiber. Moreover, MoS 2 also showed a strong affinity toward PCBs in a manner similar to its affinity for graphene. The developed method is simple and environmentally friendly as it does not require any organic solvents. Furthermore, it exhibits good sensitivity with detection limits less than 0.1ngmL -1 , linearity (0.25-100ngmL -1 ), and reproducibility (relative standard deviation below 10% for n=3). The novel SPME fibers are inexpensive, reusable, and can be easily prepared and manipulated. In addition, the saponification-HS-SPME assay was also found to be suitable for screening persistent organic pollutants in dairy products. Copyright © 2017 Elsevier B.V. All rights reserved.

Modified zeolitic imidazolate framework-8 as solid-phase microextraction Arrow coating for sampling of amines in wastewater and food samples followed by gas chromatography-mass spectrometry.

PubMed

Lan, Hangzhen; Rönkkö, Tuukka; Parshintsev, Jevgeni; Hartonen, Kari; Gan, Ning; Sakeye, Motolani; Sarfraz, Jawad; Riekkola, Marja-Liisa

2017-02-24

In this study, a novel solid phase microextration (SPME) Arrow was prepared for the sampling of volatile low molecular weight alkylamines (trimethylamine (TMA) and triethylamine (TEA)) in wastewater, salmon and mushroom samples before gas chromatographic separation with mass spectrometer as detector. Acidified zeolitic imidazolate framework-8 (A-ZIF-8) was utilized as adsorbent and poly(vinyl chloride) (PVC) as the adhesive. The custom SPME Arrow was fabricated via a physical adhesion: (1) ZIF-8 particles were suspended in a mixture of tetrahydrofuran (THF) and PVC to form a homogeneous suspension, (2) a non-coated stainless steel SPME Arrow was dipped in the ZIF-8/PVC suspension for several times to obtain a uniform and thick coating, (3) the pore size of ZIF-8 was modified by headspace exposure to hydrochloric acid in order to increase the extraction efficiency for amines. The effect of ZIF-8 concentration in PVC solution, dipping cycles and aging temperature on extraction efficiency was investigated. In addition, sampling parameters such as NaCl concentration, sample volume, extraction time, potassium hydroxide concentration, desorption temperature and desorption time were optimized. The Arrow-to-Arrow reproducibilities (RSDs) for five ZIF-8 coated Arrows were 15.6% and 13.3% for TMA and TEA, respectively. The extraction with A-ZIF-8/PVC Arrow was highly reproducible for at least 130 cycles without noticeable decrease of performance (RSD<12.5%). Headspace SPME of 7.5mL sample solution with the fabricated ZIF-8 coated Arrow achieved linear ranges of 1-200ngmL -1 for both TMA and TEA. The limit of quantitation (LOQ) was 1ngmL -1 for both TMA and TEA. The method was successfully applied to the determination of TMA and TEA in wastewater, salmon and mushroom samples giving satisfactory selectivity towards the studied amines. Copyright © 2016 Elsevier B.V. All rights reserved.

Developing a New Sampling And Analysis Method For Hydrazine And Monomethyl Hydrazine: Using a Derivatizing Agent With Solid Phase Microextraction

NASA Technical Reports Server (NTRS)

Allen, John

2001-01-01

Solid phase microextraction (SPME) will be used to develop a method for detecting monomethyl hydrazine (MMH) and hydrazine (Hz). A derivatizing agent, pentafluorobenzoyl chloride (PFBCI), is known to react readily with MMH and Hz. The SPME fiber can either be coated with PFBCl and introduced into a gaseous stream containing MMH, or PFBCl and MMH can react first in a syringe barrel and after a short equilibration period a SPME is used to sample the resulting solution. These methods were optimized and compared. Because Hz and MMH can degrade the SPME, letting the reaction occur first gave better results. Only MMH could be detected using either of these methods. Future research will concentrate on constructing calibration curves and determining the detection limit.

Analysis of Volatile Components of Cape Gooseberry (Physalis peruviana L.) Grown in Turkey by HS-SPME and GC-MS

PubMed Central

2014-01-01

Volatile components in cape gooseberry fruit at ripe stage were collected using headspace-solid phase microextraction, and analyzed by gas chromatography-mass spectrometry. Three solid phase microextraction fiber coatings (DVB/CAR/PDMS, CAR/PDMS, and PDMS/DVB) were tested for evaluation of volatile compounds. DVB/CAR/PDMS fiber showed a strong extraction capacity for volatile compounds and produced the best result in case of total peak areas. A total of 133 volatile compounds were identified in fruit pulp; among them 1-hexanol (6.86%), eucalyptol (6.66%), ethyl butanoate (6.47%), ethyl octanoate (4.01%), ethyl decanoate (3.39%), 4-terpineol (3.27%), and 2-methyl-1-butanol (3.10%) were the major components in the sample extracts. PMID:24741358

Analysis of volatile components of cape gooseberry (Physalis peruviana L.) grown in Turkey by HS-SPME and GC-MS.

PubMed

Yilmaztekin, Murat

2014-01-01

Volatile components in cape gooseberry fruit at ripe stage were collected using headspace-solid phase microextraction, and analyzed by gas chromatography-mass spectrometry. Three solid phase microextraction fiber coatings (DVB/CAR/PDMS, CAR/PDMS, and PDMS/DVB) were tested for evaluation of volatile compounds. DVB/CAR/PDMS fiber showed a strong extraction capacity for volatile compounds and produced the best result in case of total peak areas. A total of 133 volatile compounds were identified in fruit pulp; among them 1-hexanol (6.86%), eucalyptol (6.66%), ethyl butanoate (6.47%), ethyl octanoate (4.01%), ethyl decanoate (3.39%), 4-terpineol (3.27%), and 2-methyl-1-butanol (3.10%) were the major components in the sample extracts.

Cellulose nanofibers use in coated paper

NASA Astrophysics Data System (ADS)

Richmond, Finley

Cellulose Nanofibers (CNF) are materials that can be obtained by the mechanical breakdown of natural fibers. CNF have the potential to be produced at low cost in a paper mill and may provide novel properties to paper, paper coatings, paints, or other products. However, suspensions have a complex rheology even at low solid contents. To be able to coat, pump, or mix CNF at moderate solids, it is critical to understand the rheology of these suspensions and how they flow in process equipment; current papers only report the rheology up to 6% solids. Few publications are available that describe the coating of CNF onto paper or the use of CNF as an additive into a paper coating. The rheology of CNF suspensions and coatings that contain CNF were characterized with parallel-disk geometry in a controlled stress rheometer. The steady shear viscosity, the complex viscosity, the storage modulus, and the yield stress were determined for the range of solids or concentrations (2.5-10.5%). CNF were coated onto paper with a laboratory rod coater, a size press and a high speed cylindrical laboratory coater (CLC). For each case, the coat weights were measures and the properties of the papers were characterized. CNF water base suspension was found to be a shear thinning with a power law index of around 0.1. Oscillatory tests showed a linear viscoelastic region at low strains and significant storage and loss moduli even at low solids. The Cox Merz rule does not hold for CNF suspensions or coating formulations that contain CNF with complex viscosities that are about 100 times larger than the steady shear viscosities. Paper coating formulations that contain CNF were found to have viscosities and storage and loss moduli that are over ten times larger than coatings that contain starch at similar solids. CNF suspensions were coated on papers with low amount transferred on paper either at high solids or high nip loadings. The amount transferred appears to be controlled by an interaction of filtration and fluid flow mechanisms. Coatings with CNF of 5 pph (part per hundred) were not able to be applied with CLC coater due to solid like behavior of the coating: the issue seems to be the ability of the coating to flow in the pond by gravity to the blade-paper nip and not the flow in the blade region itself. Some improvement of the paper properties were found by coating CNF onto paper, but some improvements were much less than expected. This may be due to CNF soaking into the paper. Air permeability decreased and stiffness increased. Paper coatings with CNF had higher stiffness and coating strength than coatings that contained starch. CNF acts similar to starch in terms of being a co-binder. A decrease in pick resistance is seen at 5 pph CNF or starch content; this decrease likely comes from the coating layer becoming more brittle.

Study of metallic powder behavior in very low pressure plasma spraying (VLPPS) — Application to the manufacturing of titanium–aluminum coatings

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

Vautherin, B.; Planche, M.-P.; Montavon, G.

2015-08-28

In this study, metallic materials made of aluminum and titanium were manufactured implementing very low pressure plasma spraying (VLPPS). Aluminum was selected at first as a demonstrative material due to its rather low vaporization enthalpy ( i.e., 381.9 kJ·mol⁻¹). Developments were then carried out with titanium which exhibits a higher vaporization enthalpy ( i.e., 563.6 kJ·mol⁻¹). Optical emission spectroscopy (OES) was implemented to analyze the behavior of each solid precursor (metallic powders) when it is injected into the plasma jet under very low pressure ( i.e., in the 150 Pa range). Besides, aluminum, titanium and titanium–aluminum coatings were deposited inmore » the same conditions implementing a stick-cathode plasma torch operated at 50 kW, maximum power. Coating phase compositions were identified by X-Ray Diffraction (XRD). Coating elementary compositions were quantified by Glow Discharge Optical Emission Spectroscopy (GDOES) and Energy Dispersive Spectroscopy (EDS) analyses. The coating structures were observed by Scanning Electron Microscopy (SEM). The coating void content was determined by Ultra-Small Angle X-ray Scattering (USAXS). The coatings exhibit a two-scale structure corresponding to condensed vapors (smaller scale) and solidified areas (larger scale). Titanium–aluminum sprayed coatings, with various Ti/Al atomic ratios, are constituted of three phases: metastable α-Ti, Al and metastable α₂-Ti₃Al. This latter is formed at elevated temperature in the plasma flow, before being condensed. Its rather small fraction, impeded by the rather small amount of vaporized Ti, does not allow modifying however the coating hardness.« less

Solid film lubricants and thermal control coatings flown aboard the EOIM-3 MDA sub-experiment

NASA Technical Reports Server (NTRS)

Murphy, Taylor J.; David, Kaia E.; Babel, Hank W.

1995-01-01

Additional experimental data were desired to support the selection of candidate thermal control coatings and solid film lubricants for the McDonnell Douglas Aerospace (MDA) Space Station hardware. The third Evaluation of Oxygen Interactions With Materials Mission (EOIM-3) flight experiment presented an opportunity to study the effects of the low Earth orbit environment on thermal control coatings and solid film lubricants. MDA provided five solid film lubricants and two anodic thermal control coatings for EOIM-3. The lubricant sample set consisted of three solid film lubricants with organic binders one solid film lubricant with an inorganic binder, and one solid film lubricant with no binder. The anodize coating sample set consisted of undyed sulfuric acid anodize and cobalt sulfide dyed sulfuric acid anodize, each on two different substrate aluminum alloys. The organic and inorganic binders in the solid film lubricants experienced erosion, and the lubricating pigments experienced oxidation. MDA is continuing to assess the effect of exposure to the low Earth orbit environment on the life and friction properties of the lubricants. Results to date support the design practice of shielding solid film lubricants from the low Earth orbit environment. Post-flight optical property analysis of the anodized specimens indicated that there were limited contamination effects and some atomic oxygen and ultraviolet radiation effects. These effects appeared to be within the values predicted by simulated ground testing and analysis of these materials, and they were different for each coating and substrate.

40 CFR 63.4730 - What records must I keep?

Code of Federal Regulations, 2010 CFR

2010-07-01

... to determine the mass fraction of organic HAP and density for each coating, thinner, and cleaning material and the volume fraction of coating solids for each coating. If you conducted testing to determine mass fraction of organic HAP, density, or volume fraction of coating solids, you must keep a copy of...

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Nanosize relief: from phase masks to antireflection coatings on quartz and silicon

NASA Astrophysics Data System (ADS)

Verevkin, Yu K.; Klimov, A. Yu; Gribkov, B. A.; Petryakov, V. N.; Koposova, E. V.; Olaizola, Santiago M.

2008-11-01

By using the interference of pulsed radiation and a complete lithographic cycle, phase masks on quartz and antireflection structures on quartz and silicon are produced. The transmission of radiation through a corrugated vacuum—solid interface is calculated by solving rigorously an integral equation with the help of a computer program for parameters close to experimental parameters. The results of measurements are in good agreement with calculations. The methods developed in the paper can be used for manufacturing optical and semiconductor devices.

Methods of producing armor systems, and armor systems produced using such methods

DOEpatents

Chu, Henry S; Lillo, Thomas M; McHugh, Kevin M

2013-02-19

An armor system and method involves providing a core material and a stream of atomized coating material that comprises a liquid fraction and a solid fraction. An initial layer is deposited on the core material by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is less than the liquid fraction of the stream of atomized coating material on a weight basis. An outer layer is then deposited on the initial layer by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is greater than the liquid fraction of the stream of atomized coating material on a weight basis.

Development of a multi-preservative method based on solid-phase microextraction-gas chromatography-tandem mass spectrometry for cosmetic analysis.

PubMed

Alvarez-Rivera, Gerardo; Vila, Marlene; Lores, Marta; Garcia-Jares, Carmen; Llompart, Maria

2014-04-25

A simple methodology based on solid-phase microextraction (SPME) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for the simultaneous analysis of different classes of preservatives including benzoates, bronidox, 2-phenoxyethanol, parabens, BHA, BHT and triclosan in cosmetic products. In situ acetylation and subsequent organic modifier addition have been successfully implemented in the SPME process as an effective extractive strategy for matrix effect compensation and chromatographic performance improvement. Main factors affecting SPME procedure such as fiber coating, sampling mode, extraction temperature and salt addition (NaCl) were evaluated by means of a 3×2(3-1) factorial experimental design. The optimal experimental conditions were established as follows: direct solid-phase microextraction (SPME) at 40°C and addition of NaCl (20%, w/v), using a DVB/CAR/PDMS fiber coating. Due to the complexity of the studied matrices, method performance was evaluated in a representative variety of both rinse-off and leave-on samples, demonstrating to have a broad linear range (R(2)>0.9964). In general, quantitative recoveries (>85% in most cases) and satisfactory precision (RSD<13% for most of compounds) were obtained, with limits of detection (LODs) well below the maximum authorized concentrations established by the European legislation. One of the most important achievements of this work was the use of external calibration with cosmetic-matched standards to accurately quantify the target analytes. The validated methodology was successfully applied to the analysis of different types of cosmetic formulations including body milks, moisturizing creams, deodorants, sunscreen, bath gel, dental cream and make-up products amongst others, demonstrating to be a reliable multi-preservative methododology for routine control. Copyright © 2014 Elsevier B.V. All rights reserved.

Modification of polydopamine-coated Fe3O4 nanoparticles with multi-walled carbon nanotubes for magnetic-μ-dispersive solid-phase extraction of antiepileptic drugs in biological matrices.

PubMed

Zhang, Ruiqi; Wang, Siming; Yang, Ye; Deng, Yulan; Li, Di; Su, Ping; Yang, Yi

2018-06-01

In this study, multi-walled carbon nanotubes were coated on the surface of magnetic nanoparticles modified by polydopamine. The synthesized composite was characterized and applied to magnetic-μ-dispersive solid-phase extraction of oxcarbazepine (OXC), phenytoin (PHT), and carbamazepine (CBZ) from human plasma, urine, and cerebrospinal fluid samples prior to analysis by a high-performance liquid chromatography-photodiode array detector. The extraction parameters were investigated and the optimum condition was obtained when the variables were set to the following: sorbent type, Fe 3 O 4 @polyDA-MWCNTs (length < 2 μm); sample pH, 6; amount of sorbent, 15 mg; sorption time, 1.5 min at room temperature; type and volume of the eluent, 2.5 mL methanol; and salt content, none added. Under the optimized conditions, the calibration curves are linear in the concentration range 2-2000 ng/mL, the limits of detection are in the range 0.4-3.1 ng/mL, and the relative standard deviations and relative recoveries of plasma (spiked at 200 ng/mL) and CSF (spiked at 50 ng/mL) are in the ranges 1.4-8.2% and 92.8-96.5%, respectively. The applicability of the method was successfully confirmed by extraction and determination of OXC, PHT, and CBZ in biological matrices. Graphical abstract Magnetic multi-walled carbon nanotube core-shell composites were applied as magnetic-μ-dispersive solid-phase extraction adsorbents for determination of antiepileptic drugs in biological matrices.

Phase Transformation of Droplets into Particles and Nucleation in Atmospheric Pressure Discharges

NASA Astrophysics Data System (ADS)

Iqbal, M. M.; Stallard, C. P.; Dowling, D. P.; Turner, M. M.

2013-09-01

We investigate the mechanism of phase transformation of liquid precursor droplets into nano-particulates in an atmospheric pressure discharge (APD). This phase transformation is possible when the solid to a liquid mass ratio of slurry droplet reaches a threshold value. The behaviour of phase transformation of a single slurry droplet of HMDSO is described by developing a numerical model under the saturation condition of evaporation. It is observed from the temporal evolution of inner radius (Ri) of a single slurry droplet that its value approaches zero before the entire shifting of a liquid phase and which explains with an expansion in the crust thickness (Ro - Ri) . The solid traces of nano-particles are observed experimentally on the surface coating depositions because the time for transferring the slurry droplet of HMDSO into solid state is amplified with an increment in the radii of droplets and the entire phase transition occurs within residence time for the nano-sized liquid droplets. The GDE coupled with discharge plasma is numerically solved to describe the mechanism of nucleation of nano-sized particles in APD plasma under similar conditions of the experiment. The growth of nucleation in APD plasma depends on the type of liquid precursor, such as HMDSO, TEOS and water, which is verified with a sharp peak in the nucleation rate and saturation ratio. Science Foundation Ireland under Grant No. 08/SRC/I1411.

Effect of Copper Oxide, Titanium Dioxide, and Lithium Fluoride on the Thermal Behavior and Decomposition Kinetics of Ammonium Nitrate

NASA Astrophysics Data System (ADS)

Vargeese, Anuj A.; Mija, S. J.; Muralidharan, Krishnamurthi

2014-07-01

Ammonium nitrate (AN) is crystallized along with copper oxide, titanium dioxide, and lithium fluoride. Thermal kinetic constants for the decomposition reaction of the samples were calculated by model-free (Friedman's differential and Vyzovkins nonlinear integral) and model-fitting (Coats-Redfern) methods. To determine the decomposition mechanisms, 12 solid-state mechanisms were tested using the Coats-Redfern method. The results of the Coats-Redfern method show that the decomposition mechanism for all samples is the contracting cylinder mechanism. The phase behavior of the obtained samples was evaluated by differential scanning calorimetry (DSC), and structural properties were determined by X-ray powder diffraction (XRPD). The results indicate that copper oxide modifies the phase transition behavior and can catalyze AN decomposition, whereas LiF inhibits AN decomposition, and TiO2 shows no influence on the rate of decomposition. Possible explanations for these results are discussed. Supplementary materials are available for this article. Go to the publisher's online edition of the Journal of Energetic Materials to view the free supplemental file.

Surface-modified multifunctional MIP nanoparticles

NASA Astrophysics Data System (ADS)

Moczko, Ewa; Poma, Alessandro; Guerreiro, Antonio; Perez de Vargas Sansalvador, Isabel; Caygill, Sarah; Canfarotta, Francesco; Whitcombe, Michael J.; Piletsky, Sergey

2013-04-01

The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as a protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity (PEG methacrylate); electro-activity (vinylferrocene); fluorescence (eosin acrylate); thiol groups (pentaerythritol tetrakis(3-mercaptopropionate)). The method has broad applicability and can be used to produce multifunctional imprinted nanoparticles with potential for further application in the biosensors, diagnostics and biomedical fields and as an alternative to natural receptors.The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as a protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity (PEG methacrylate); electro-activity (vinylferrocene); fluorescence (eosin acrylate); thiol groups (pentaerythritol tetrakis(3-mercaptopropionate)). The method has broad applicability and can be used to produce multifunctional imprinted nanoparticles with potential for further application in the biosensors, diagnostics and biomedical fields and as an alternative to natural receptors. Electronic supplementary information (ESI) available: Details of the synthesis of eosin O-acrylate monomer and 1H-NMR spectrum of MIP NPs post-derivatised with PEG shell. See DOI: 10.1039/c3nr00354j

Role of the AP2 β-Appendage Hub in Recruiting Partners for Clathrin-Coated Vesicle Assembly

PubMed Central

Burtey, Anne; Praefcke, Gerrit J. K; Peak-Chew, Sew-Yeu; Mills, Ian G; Benmerah, Alexandre; McMahon, Harvey T

2006-01-01

Adaptor protein complex 2 α and β-appendage domains act as hubs for the assembly of accessory protein networks involved in clathrin-coated vesicle formation. We identify a large repertoire of β-appendage interactors by mass spectrometry. These interact with two distinct ligand interaction sites on the β-appendage (the “top” and “side” sites) that bind motifs distinct from those previously identified on the α-appendage. We solved the structure of the β-appendage with a peptide from the accessory protein Eps15 bound to the side site and with a peptide from the accessory cargo adaptor β-arrestin bound to the top site. We show that accessory proteins can bind simultaneously to multiple appendages, allowing these to cooperate in enhancing ligand avidities that appear to be irreversible in vitro. We now propose that clathrin, which interacts with the β-appendage, achieves ligand displacement in vivo by self-polymerisation as the coated pit matures. This changes the interaction environment from liquid-phase, affinity-driven interactions, to interactions driven by solid-phase stability (“matricity”). Accessory proteins that interact solely with the appendages are thereby displaced to areas of the coated pit where clathrin has not yet polymerised. However, proteins such as β-arrestin (non-visual arrestin) and autosomal recessive hypercholesterolemia protein, which have direct clathrin interactions, will remain in the coated pits with their interacting receptors. PMID:16903783

Investigation on the parameter optimization and performance of laser cladding a gradient composite coating by a mixed powder of Co50 and Ni/WC on 20CrMnTi low carbon alloy steel

NASA Astrophysics Data System (ADS)

Shi, Yan; Li, Yunfeng; Liu, Jia; Yuan, Zhenyu

2018-02-01

In this study, a gradient composite coating was manufactured on 20CrMnTi alloy steel by laser cladding. The laser power, cladding scan velocity and powder flow rate were selected as influencing factors of the orthogonal cladding experiments. The influencing factors were optimized by the comprehensive analysis of Taguchi OA and TOPSIS method. The high significant parameters and the predicted results were confirmed by the ANOVA method. The macromorphology and microstructures are characterized by using laser microscope, SEM, XRD and microhardness tester. Comparison tests of wear resistance of gradient composite coating, 20CrMnTi cemented quenching sample and the 20CrMnTi sample were conducted on the friction-wear tester. The results show that the phases are γ-Co solid solution, Co3B, M23C6 and etc. The interlayers and wear-resisting layer also contain new hard phases as WC, W2C. The microhardness of the gradient coating was increased to 3 times as compared with that of the 20CrMnTi substrate. The wear resistance of the gradient composite coating and 20CrMnTi cemented quenching sample was enhanced to 36.4 and 15.9 times as compared with that of the 20CrMnTi.

The use of trivalent chromium bath to obtain a solar selective black chromium coating

NASA Astrophysics Data System (ADS)

Survilienė, S.; Češūnienė, A.; Juškėnas, R.; Selskienė, A.; Bučinskienė, D.; Kalinauskas, P.; Juškevičius, K.; Jurevičiūtė, I.

2014-06-01

Black chromium coatings were electrodeposited from a trivalent chromium bath using a ZnO additive as a second main component. Black chromium was electrodeposited on steel and copper plates and substrates plated with bright nickel prior to black chromium electrodeposition. The black chromium coatings were characterized by XRD and SEM. The XRD data suggest that the phase structure of black chromium may be defined as a zinc solid solution in chromium or a chromium solid solution in zinc depending on the chromium/zinc ratio in the deposit. The role of substrate finish was evaluated through the corrosion resistance and reflectance of black chromium. According to corrosion tests the samples plated with bright nickel prior to black chromium deposition have shown the highest corrosion resistance. The electrodeposited black chromium possesses good optical properties for the absorption of solar energy. The absorption coefficient of black chromium was found to be over 0.99 for the samples obtained without the Ni undercoat and below 0.99 for those obtained with the use of Ni undercoat. However, the use of nickel undercoat before black chromium plating is recommended because it remarkably improves the corrosion resistance of samples.

Nano powders, components and coatings by plasma technique

DOEpatents

McKechnie, Timothy N [Brownsboro, AL; Antony, Leo V. M. [Huntsville, AL; O'Dell, Scott [Arab, AL; Power, Chris [Guntersville, AL; Tabor, Terry [Huntsville, AL

2009-11-10

Ultra fine and nanometer powders and a method of producing same are provided, preferably refractory metal and ceramic nanopowders. When certain precursors are injected into the plasma flame in a reactor chamber, the materials are heated, melted and vaporized and the chemical reaction is induced in the vapor phase. The vapor phase is quenched rapidly to solid phase to yield the ultra pure, ultra fine and nano product. With this technique, powders have been made 20 nanometers in size in a system capable of a bulk production rate of more than 10 lbs/hr. The process is particularly applicable to tungsten, molybdenum, rhenium, tungsten carbide, molybdenum carbide and other related materials.

Nano powders, components and coatings by plasma technique

NASA Technical Reports Server (NTRS)

McKechnie, Timothy N. (Inventor); Antony, Leo V. M. (Inventor); O'Dell, Scott (Inventor); Power, Chris (Inventor); Tabor, Terry (Inventor)

2009-01-01

Ultra fine and nanometer powders and a method of producing same are provided, preferably refractory metal and ceramic nanopowders. When certain precursors are injected into the plasma flame in a reactor chamber, the materials are heated, melted and vaporized and the chemical reaction is induced in the vapor phase. The vapor phase is quenched rapidly to solid phase to yield the ultra pure, ultra fine and nano product. With this technique, powders have been made 20 nanometers in size in a system capable of a bulk production rate of more than 10 lbs/hr. The process is particularly applicable to tungsten, molybdenum, rhenium, tungsten carbide, molybdenum carbide and other related materials.

Pressure cell for investigations of solid-liquid interfaces by neutron reflectivity.

PubMed

Kreuzer, Martin; Kaltofen, Thomas; Steitz, Roland; Zehnder, Beat H; Dahint, Reiner

2011-02-01

We describe an apparatus for measuring scattering length density and structure of molecular layers at planar solid-liquid interfaces under high hydrostatic pressure conditions. The device is designed for in situ characterizations utilizing neutron reflectometry in the pressure range 0.1-100 MPa at temperatures between 5 and 60 °C. The pressure cell is constructed such that stratified molecular layers on crystalline substrates of silicon, quartz, or sapphire with a surface area of 28 cm(2) can be investigated against noncorrosive liquid phases. The large substrate surface area enables reflectivity to be measured down to 10(-5) (without background correction) and thus facilitates determination of the scattering length density profile across the interface as a function of applied load. Our current interest is on the stability of oligolamellar lipid coatings on silicon surfaces against aqueous phases as a function of applied hydrostatic pressure and temperature but the device can also be employed to probe the structure of any other solid-liquid interface.

A basic study on Thermosyphon-type thermal storage unit (TSU) using Nanofluid as the heat transfer medium

NASA Astrophysics Data System (ADS)

Li, Shuang-Fei; Wang, Ping-Yang; Liu, Zhen-hua

2018-05-01

This study proposed a novel thermosyphon-type thermal storage unit using water-based CuO nanofluid as the phase-change heat transfer medium. Seven tubular canisters containing solid-liquid phase-change material (PCM) with peak melting temperature of 100 °C were placed vertically into the center of the TSU which is a vertical cylindrical vessel made of stainless steel. Coat formed by depositing nanoparticles during the phase-change process was adopted to increase the wettability of the heat transfer surfaces of the canisters. We investigated the phase-change heat transfer, as well as the heat-storage and heat-release properties, of the TSU through experimental and computational analysis. Our results demonstrate that this thermal storage unit construction can propose good heat transfer and heat-storage/heat-release performance. The coating of nanoparticles onto the heat transfer surfaces increases the surface wettability and improves both the evaporation and condensation heat transfer. The main thermal resistance in the TSU results from the conductive heat transfer inside of the PCM. All phase-change thermal resistance of liquid film in charging and discharging processes can be ignored in this TSU.

Wet powder processing of sol-gel derived mesoporous silica-hydroxyapatite hybrid powders.

PubMed

Andersson, Jenny; Johannessen, Espen; Areva, Sami; Järn, Mikael; Lindén, Mika

2006-08-01

This paper describes a method by which a porous silica coating layer can be obtained on different apatite particles through a simple sol-gel synthesis route. Sol-gel derived powders of hydroxyapatite (HAP) and beta tricalciumphosphate (beta-TCP) were coated with a mesoporous silica using C16TAB (hexadecyltrimethylammonium bromide) as a template in order to induce mesophase formation. Further calcination of the material removes the template from the mesophase and leaves a highly ordered hexagonal arranged mesoporous silica structure with a core of HAP/beta-TCP. The phase purity of the SiO2/apatite composites has been thoroughly investigated by the means of FT-IR, XRD, and solid state 31P MAS NMR. The phase purity of these materials is shown to be dependent on the solubility properties of the used apatites. The hybrid materials are suitable as a multifunctional biomaterial where osteoconductive properties can be combined with drug delivery.

Micelle assisted thin-film solid phase microextraction: a new approach for determination of quaternary ammonium compounds in environmental samples.

PubMed

Boyacı, Ezel; Pawliszyn, Janusz

2014-09-16

Determination of quaternary ammonium compounds (QACs) often is considered to be a challenging undertaking owing to secondary interactions of the analytes' permanently charged quaternary ammonium head or hydrophobic tail with the utilized labware. Here, for the first time, a micelle assisted thin-film solid phase microextraction (TF-SPME) using a zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) as a matrix modifier is introduced as a novel approach for in-laboratory sample preparation of the challenging compounds. The proposed micelle assisted TF-SPME method offers suppression/enhancement free electrospray ionization of analytes in mass spectrometric detection, minimal interaction of the micelles with the TF-SPME coating, and chromatographic stationary phase and analysis free of secondary interactions. Moreover, it was found that the matrix modifier has multiple functions; when its concentration is found below the critical micelle concentration (CMC), the matrix modifier primarily acts as a surface deactivator; above its CMC, it acts as a stabilizer for QACs. Additionally, shorter equilibrium extraction times in the presence of the modifier demonstrated that micelles also assist in the transfer of analytes from the bulk of the sample to the surface of the coating. The developed micelle assisted TF-SPME protocol using the 96-blade system requires only 30 min of extraction and 15 min of desorption. Together with a conditioning step (15 min), the entire method is 60 min; considering the advantage of using the 96-blade system, if all the blades in the brush are used, the sample preparation time per sample is 0.63 min. Moreover, the recoveries for all analytes with the developed method were found to range within 80.2-97.3%; as such, this method can be considered an open bed solid phase extraction. The proposed method was successfully validated using real samples.

Boundary layers of aqueous surfactant and block copolymer solutions against hydrophobic and hydrophilic solid surfaces

NASA Astrophysics Data System (ADS)

Steitz, Roland; Schemmel, Sebastian; Shi, Hongwei; Findenegg, Gerhard H.

2005-03-01

The boundary layer of aqueous surfactants and amphiphilic triblock copolymers against flat solid surfaces of different degrees of hydrophobicity was investigated by neutron reflectometry (NR), grazing incidence small angle neutron scattering (GISANS) and atomic force microscopy (AFM). Solid substrates of different hydrophobicities were prepared by appropriate surface treatment or by coating silicon wafers with polymer films of different chemical natures. For substrates coated with thin films (20-30 nm) of deuterated poly(styrene) (water contact angle \\theta_{\\mathrm {w}} \\approx 90^\\circ ), neutron reflectivity measurements on the polymer/water interface revealed a water depleted liquid boundary layer of 2-3 nm thickness and a density about 90% of the bulk water density. No pronounced depletion layer was found at the interface of water against a less hydrophobic polyelectrolyte coating (\\theta_{\\mathrm {w}} \\approx 63^\\circ ). It is believed that the observed depletion layer at the hydrophobic polymer/water interface is a precursor of the nanobubbles which have been observed by AFM at this interface. Decoration of the polymer coatings by adsorbed layers of nonionic CmEn surfactants improves their wettability by the aqueous phase at surfactant concentrations well below the critical micellar concentration (CMC) of the surfactant. Here, GISANS experiments conducted on the system SiO2/C8E4/D2O reveal that there is no preferred lateral organization of the C8E4 adsorption layers. For amphiphilic triblock copolymers (PEO-PPO-PEO) it is found that under equilibrium conditions they form solvent-swollen brushes both at the air/water and the solid/water interface. In the latter case, the brushes transform to uniform, dense layers after extensive rinsing with water and subsequent solvent evaporation. The primary adsorption layers maintain properties of the precursor brushes. In particular, their thickness scales with the number of ethylene oxide units (EO) of the block copolymer. In the case of dip-coating without subsequent rinsing, surface patterns of the presumably crystalline polymer on top of the primary adsorption layer develop upon drying under controlled conditions. The morphology depends mainly on the nominal surface coverage with the triblock copolymer. Similar morphologies are found on bare and polystyrene-coated silicon substrates, indicating that the surface patterning is mainly driven by segregation forces within the polymer layers and not by interactions with the substrate.

Filter paper solid-phase radioimmunoassay for human rotavirus surface immunoglobulins.

PubMed Central

Watanabe, H; Holmes, I H

1977-01-01

A filter paper solid-phase radioimmunoassay has been developed. Filter paper disks adsorbed a large amount of rotavirus and serum globulin and gave small mean variation of coating and low background binding. The rotavirus isolated from stools from infants with acute enteritis 1, 3, and 4 days after onset of symptoms was shown to be already covered with immunoglobulin G (IgG), IgA, and IgM antibodies by this radioimmunoassay, by immunoelectrophoresis, and by immune electron microscopy. The immunoglobulins covering the virus particle were partially separated during 125I labeling and eluted at the position expected for IgG during Sephadex G-200 gel filtration. Rabbit antiserum prepared against purified fecal rotavirus contained not only rotavirus antibodies but also a fairly large amount of immunoglobulin antibody, reflecting the antibodies on the rotavirus particle surface. Images PMID:199613

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format

NASA Astrophysics Data System (ADS)

Smolinska-Kempisty, Katarzyna; Guerreiro, Antonio; Canfarotta, Francesco; Cáceres, César; Whitcombe, Michael J.; Piletsky, Sergey

2016-11-01

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays.

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format.

PubMed

Smolinska-Kempisty, Katarzyna; Guerreiro, Antonio; Canfarotta, Francesco; Cáceres, César; Whitcombe, Michael J; Piletsky, Sergey

2016-11-24

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays.

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format

PubMed Central

Smolinska-Kempisty, Katarzyna; Guerreiro, Antonio; Canfarotta, Francesco; Cáceres, César; Whitcombe, Michael J.; Piletsky, Sergey

2016-01-01

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays. PMID:27883023

Utilizing thin-film solid-phase extraction to assess the effect of organic carbon amendments on the bioavailability of DDT and dieldrin to earthworms

USGS Publications Warehouse

Andrade, Natasha A.; Centofanti, Tiziana; McConnell, Laura L.; Hapeman, Cathleen J.; Torrents, Alba; Anh, Nguyen; Beyer, W. Nelson; Chaney, Rufus L.; Novak, Jeffrey M.; Anderson, Marya O.; Cantrell, Keri B.

2014-01-01

Improved approaches are needed to assess bioavailability of hydrophobic organic compounds in contaminated soils. Performance of thin-film solid-phase extraction (TF-SPE) using vials coated with ethylene vinyl acetate was compared to earthworm bioassay (Lumbricus terrestris). A DDT and dieldrin contaminated soil was amended with four organic carbon materials to assess the change in bioavailability. Addition of organic carbon significantly lowered bioavailability for all compounds except for 4,4′-DDT. Equilibrium concentrations of compounds in the polymer were correlated with uptake by earthworms after 48d exposure (R2 = 0.97; p 40yr of aging. Results show that TF-SPE can be useful in examining potential risks associated with contaminated soils and to test effectiveness of remediation efforts.

Sorption of amitriptyline and amphetamine to mixed-mode solid-phase microextraction in different test conditions.

PubMed

Peltenburg, Hester; Droge, Steven T J; Hermens, Joop L M; Bosman, Ingrid J

2015-04-17

A solid-phase microextraction (SPME) method based on a sampler coating that includes strong cation groups (C18/SCX) is explored as a rapid direct sampling tool to detect and quantify freely dissolved basic drugs. Sampling kinetics, sorption isotherms and competitive effects on extraction yields in mixtures were tested for amphetamine and the relatively large/hydrophobic tricyclic antidepressant amitriptyline. Both compounds are >99% ionized at pH 7.4 but their affinity for the C18/SCX fiber is markedly different with distribution coefficients (Dfw values) of 2.49±0.02 for amphetamine and 4.72±0.10 for amitriptyline. Typical changes in electrolyte homeostasis that may occur in biomedical samples were simulated by altering pH and ionic composition (Na(+) and K(+) concentrations). These changes were shown to affect C18/SCX sorption affinities of the tested drugs with less than 0.2log units. At relatively low fiber loadings (<10mmol/L coating) and at all tested exposure times, linear sorption isotherms were obtained for both compounds but at aqueous concentrations of the individual drugs corresponding to concentrations in blood that are lethal, sorption isotherms became strongly nonlinear. Competition effects within binary mixtures occurred only if combinations of aqueous concentrations resulted in total fiber loadings that were in the nonlinear range of the SPME sorption isotherm for the individual compounds. We also compared sorption to the (prototype) C18/SCX SPME coating with analogue (biocompatible) C18 coated SPME fibers. C18/SCX fibers show increased sorption affinity for cationic compounds compared to C18 fibers, as tested using amitriptyline, amphetamine and trimethoprim. Surprisingly, sorption affinity of these ionized compounds for the C18 SPME fibers were within 1log unit of the C18/SCX SPME fibers. This shows that the strong cation exchange groups within the C18/SCX coating only has a relatively small contribution to the total sorption affinity of cationic compounds. Also the role of negatively charged silanol groups in both the C18 and C18/SCX coating seems small, as anionic diclofenac species sorbed strongly to the C18 fiber. Ionized organic species seem to be substantially adsorbed to the high surface area of C18 in SPME types using porous silica based coatings. Copyright © 2015 Elsevier B.V. All rights reserved.

Microstructure and mechanical properties of plasma sprayed HA/YSZ/Ti-6Al-4V composite coatings.

PubMed

Khor, K A; Gu, Y W; Pan, D; Cheang, P

2004-08-01

Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA/yttria stabilized zirconia (YSZ)/Ti-6Al-4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings were developed. Ti-6Al-4V powders coated with fine YSZ and HA particles were prepared through a unique ceramic slurry mixing method. The so-formed composite powder was employed as feedstock for plasma spraying of the HA/YSZ/Ti-6Al-4V coatings. The influence of net plasma energy, plasma spray standoff distance, and post-spray heat treatment on microstructure, phase composition and mechanical properties were investigated. Results showed that coatings prepared with the optimum plasma sprayed condition showed a well-defined splat structure. HA/YSZ/Ti-6Al-4V solid solution was formed during plasma spraying which was beneficial for the improvement of mechanical properties. There was no evidence of Ti oxidation from the successful processing of YSZ and HA coated Ti-6Al-4V composite powders. Small amount of CaO apart from HA, ZrO(2) and Ti was present in the composite coatings. The microhardness, Young's modulus, fracture toughness, and bond strength increased significantly with the addition of YSZ. Post-spray heat treatment at 600 degrees C and 700 degrees C for up to 12h was found to further improve the mechanical properties of coatings. After the post-spray heat treatment, 17.6% increment in Young's modulus (E) and 16.3% increment in Vicker's hardness were achieved. The strengthening mechanisms of HA/YSZ/Ti-6Al-4V composite coatings were related to the dispersion strengthening by homogeneous distribution of YSZ particles in the matrix, the good mechanical properties of Ti-6Al-4V and the formation of solid solution among HA, Ti alloy and YSZ components.

Phase separation in NiCrN coatings induced by N2 addition in the gas phase: A way to generate magnetic thin films by reactive sputtering of a non-magnetic NiCr target

NASA Astrophysics Data System (ADS)

Luciu, I.; Duday, D.; Choquet, P.; Perigo, E. A.; Michels, A.; Wirtz, T.

2016-12-01

Magnetic coatings are used for a lot of applications from data storage in hard discs, spintronics and sensors. Meanwhile, magnetron sputtering is a process largely used in industry for the deposition of thin films. Unfortunately, deposition of magnetic coatings by magnetron sputtering is a difficult task due to the screening effect of the magnetic target lowering the magnetic field strength of the magnet positioned below the target, which is used to generate and trap ions in the vicinity of the target surface to be sputtered. In this work we present an efficient method to obtain soft magnetic thin films by reactive sputtering of a non-magnetic target. The aim is to recover the magnetic properties of Ni after dealloying of Ni and Cr due to the selective reactivity of Cr with the reactive nitrogen species generated during the deposition process. The effects of nitrogen content on the dealloying and DC magnetron sputtering (DCMS) deposition processes are studied here. The different chemical compositions, microstructures and magnetic properties of DCMS thin films obtained by sputtering in reactive gas mixtures with different ratios of Ar/N2 from a non-magnetic Ni-20Cr target have been determined. XPS data indicate that the increase of nitrogen content in the films has a strong influence on the NiCr phase decomposition into Ni and CrN, leading to ferromagnetic coatings due to the Ni phase. XRD results show that the obtained Ni-CrN films consist of a metallic fcc cubic Ni phase mixed with fcc cubic CrN. The lattice parameter decreases with the N2 content and reaches the theoretical value of the pure fcc-Ni, when Cr is mostly removed from the Ni-Cr phase. Dealloying of Cr from a Ni80-Cr20 solid solution is achieved in our experimental conditions and the deposition of Ni ferromagnetic coatings embedding CrN from a non-magnetic target is possible with reactive DC magnetron sputtering.

The effect of complex black carbon microphysics on the determination of the optical properties of brown carbon

NASA Astrophysics Data System (ADS)

Liu, Dantong; Taylor, Jonathan W.; Young, Dominque E.; Flynn, Michael J.; Coe, Hugh; Allan, James D.

2015-01-01

of the impacts of brown carbon (BrC) requires accurate determination of its physical properties, but a model must be invoked to derive these from instrument data. Ambient measurements were made in London at a site influenced by traffic and solid fuel (principally wood) burning, apportioned by single particle soot photometer data and optical properties measured using multiwavelength photoacoustic spectroscopy. Two models were applied: a commonly used Mie model treating the particles as single-coated spheres and a Rayleigh-Debye-Gans approximation treating them as aggregates of smaller-coated monomers. The derived solid fuel BrC parameters at 405 nm were found to be highly sensitive to the model treatment, with a mass absorption cross section ranging from 0.47 to 1.81 m2/g and imaginary refractive index from 0.013 to 0.062. This demonstrates that a detailed knowledge of particle morphology must be obtained and invoked to accurately parameterize BrC properties based on aerosol phase measurements.

Reactive Capping Mat Development and Evaluation for Sequestering Contaminants in Sediments

DTIC Science & Technology

2011-08-01

semi-permeable membrane devices (SPMDs) and solid phase micro-extraction (SPME) fibers . Peepers are expression samplers constructed of...in fish organs. The SPME fibers are coated with a liquid polymer that allows organic contaminants to establish equilibria between the fiber and the...between 10 and 20 cm of 300/200 µm polydimethylsiloxan (PMDS) fiber (Fiberguide) per replicate sample. Fibers were deployed at 10 cm lengths in a

Determination of Aromatic Amines Using Solid-Phase Microextraction Based on an Ionic Liquid-Mediated Sol-Gel Technique.

PubMed

Abbasi, Vajihe; Sarafraz-Yazdi, Ali; Amiri, Amirhassan; Vatani, Hossein

2016-04-01

A headspace solid-phase microextraction (HS-SPME) method was developed for isolation of monocyclic aromatic amines from water samples followed by gas chromatography-flame ionization detector (GC-FID). In this work, the effect of the presence of ionic liquid (namely, 1-hexyl-3-methyl-imidazolium hexafluorophosphate [C6MIM][PF6]) was investigated in the sol-gel coating solutions on the morphology and extraction behavior of the resulting hybrid organic-inorganic sol-gel sorbents utilized in SPME. Hydroxy-terminated poly(dimethylsiloxane) (PDMS) was used as the sol-gel active organic component for sol-gel hybrid coatings. Two different coated fibers that were prepared are PDMS and PDMS-IL ([C6MIM][PF6]) fibers. Under the optimal conditions, the method detection limits (S/N = 3) with PDMS-IL were in the range of 0.001-0.1 ng/mL and the limits of quantification (S/N = 10) between 0.005 and 0.5 ng/mL. The relative standard deviations for one fiber (n = 5) were obtained from 3.1 up to 8.5% and between fibers or batch to batch (n = 3) in the range of 5.3-10.1%. The developed method was successfully applied to real water and juice fruits samples while the relative recovery percentages obtained for the spiked water samples at 0.1 ng/mL were from 83.3 to 95.0%. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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.

Synthesis and characterization of core-shell magnetic molecularly imprinted polymers for solid-phase extraction and determination of Rhodamine B in food.

PubMed

Su, Xiaomeng; Li, Xiaoyan; Li, Junjie; Liu, Min; Lei, Fuhou; Tan, Xuecai; Li, Pengfei; Luo, Weiqiang

2015-03-15

Core-shell magnetic molecularly imprinted polymers (MIPs) nanoparticles (NPs), in which a Rhodamine B-imprinted layer was coated on Fe3O4 NPs. were synthesized. First, Fe3O4 NPs were prepared by a coprecipitation method. Then, amino-modified Fe3O4 NPs (Fe3O4@SiO2-NH2) was prepared. Finally, the MIPs were coated on the Fe3O4@SiO2-NH2 surface by the copolymerization with functional monomer, acrylamide, using a cross-linking agent, ethylene glycol dimethacrylate; an initiator, azobisisobutyronitrile and a template molecule, Rhodamine B. The Fe3O4@MIPs were characterized using a scanning electron microscope, Fourier transform infrared spectrometer, vibrating sample magnetometer, and re-binding experiments. The Fe3O4@MIPs showed a fast adsorption equilibrium, a highly improved imprinting capacity, and significant selectivity; they could be used as a solid-phase extraction material and detect illegal addition Rhodamine B in food. A method was developed for the selective isolation and enrichment of Rhodamine B in food samples with recoveries in the range 78.47-101.6% and the relative standard deviation was <2%. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development and application of a new solid-phase microextraction fiber by sol-gel technology on titanium wire.

PubMed

Es-haghi, Ali; Hosseini, Seyed Maryam; Khoshhesab, Zahra Monsef

2012-09-12

Novel solid-phase microextraction fibers were prepared based on sol-gel technique. Commonly used fused silica substrate was replaced by titanium wire which provided high strength and longer fiber life cycle. Titanium isopropoxide was employed as the precursor which provides a sol solution containing Ti-OH groups and shows more tendencies to the molecularly similar group on the substrate. Three different polymers, poly (dimethylsiloxane) (PDMS), poly(ethylenepropyleneglycol)-monobutyl ether (Ucon) and polyethylene glycol (PEG) were employed as coating polymer in preparing three different fibers. The applicability of these fibers was assessed for the headspace SPME (HS-SPME) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water sample followed by gas chromatography-mass spectrometry (GC-MS). Effects of different parameters such as fiber coating type, extraction condition, desorption condition were investigated and optimized. Under the optimized conditions, LODs and LOQs of 0.75-10 μg L(-1) (S/N=3) and 1-20 μg L(-1) (S/N=10) were respectively obtained. The method showed linearity in the range of 10-25,000 μg L(-1) with correlation coefficient of >0.99. The relative standard deviation was less than 8%. Copyright © 2012 Elsevier B.V. All rights reserved.

Solid-phase microfibers based on polyethylene glycol modified single-walled carbon nanotubes for the determination of chlorinated organic carriers in textiles.

PubMed

Zhang, Wei-Ya; Sun, Yin; Wang, Cheng-Ming; Wu, Cai-Ying

2011-09-01

Based on polyethylene glycol modified single-walled carbon nanotubes, a novel sol-gel fiber coating was prepared and applied to the headspace microextraction of chlorinated organic carriers (COCs) in textiles by gas chromatography-electron capture detection. The preparation of polyethylene glycol modified single-walled carbon nanotubes and the sol-gel fiber coating process was stated and confirmed by infrared spectra, Raman spectroscopy, and scanning electron microscopy. Several parameters affecting headspace microextraction, including extraction temperature, extraction time, salting-out effect, and desorption time, were optimized by detecting 11 COCs in simulative sweat samples. Compared with the commercial solid-phase microextraction fibers, the sol-gel polyethylene glycol modified single-walled carbon nanotubes fiber showed higher extraction efficiency, better thermal stability, and longer life span. The method detection limits for COCs were in the range from 0.02 to 7.5 ng L(-1) (S/N = 3). The linearity of the developed method varied from 0.001 to 50 μg L(-1) for all analytes, with coefficients of correlation greater than 0.974. The developed method was successfully applied to the analysis of trace COCs in textiles, the recoveries of the analytes indicated that the developed method was considerably useful for the determination of COCs in ecological textile samples.

Polyaniline-coated cigarette filters as a solid-phase extraction sorbent for the extraction and enrichment of polycyclic aromatic hydrocarbon in water samples.

PubMed

Bunkoed, Opas; Rueankaew, Thanaschaphorn; Nurerk, Piyaluk; Kanatharana, Proespichaya

2016-06-01

Polyaniline coated cigarette filters were successfully synthesized and used as a solid-phase extraction sorbent for the extraction and preconcentration of polycyclic aromatic hydrocarbons in water samples. The polyaniline helped to enhance the adsorption ability of polycyclic aromatic hydrocarbons on the sorbent through π-π interactions. The high porosity and large surface area of the cigarette filters helped to reduce backpressure and can be operated with high sample flow rate without loss of extraction efficiency. The developed sorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The parameters that affected the extraction efficiencies, i.e. polymerization time, type of desorption solvent and its volume, sample flow rate, sample volume, sample pH, ionic strength, and organic modifier were investigated. Under the optimal conditions, the method was linear over the range of 0.5-10 μg/L and a detection limit of 0.5 ng/L. This simple, rapid, and cost-effective method was successfully applied to the preconcentration of polycyclic aromatic hydrocarbons from water samples. The developed method provided a high enrichment factor with good extraction efficiency (85-98%) and a relative standard deviation <10%. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Knitting aromatic polymers for efficient solid-phase microextraction of trace organic pollutants.

PubMed

Liu, Shuqin; Hu, Qingkun; Zheng, Juan; Xie, Lijun; Wei, Songbo; Jiang, Ruifen; Zhu, Fang; Liu, Yuan; Ouyang, Gangfeng

2016-06-10

A series of knitting aromatic polymers (KAPs) were successfully synthesized using a simple one-step Friedel-Crafts alkylation of aromatic monomers and were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then, as-synthesized KAPs with large surface areas, unique pore structures and high thermal stability were prepared as solid-phase microextraction (SPME) coatings that exhibited good extraction abilities for a series of benzene compounds (i.e., benzene, toluene, ethylbenzene and m-xylene, which are referred to as BTEX) and polycyclic aromatic hydrocarbons (PAHs). Under the optimized conditions, the methodologies established for the determination of BTEX and PAHs using the KAPs-triPB and KAPs-B coatings, respectively, possessed wide linear ranges, low limits of detection (LODs, 0.10-1.13ngL(-1) for BTEX and 0.05-0.49ngL(-1) for PAHs) and good reproducibility. Finally, the proposed methods were successfully applied to the determination of BTEX and PAHs in environmental water samples, and satisfactory recoveries (93.6-124.2% for BTEX and 77.2-113.3% for PAHs) were achieved. This study provides a benchmark for exploiting novel microporous organic polymers (MOPs) for SPME applications. Copyright © 2016 Elsevier B.V. All rights reserved.

An electrochemically enhanced solid-phase microextraction approach based on a multi-walled carbon nanotubes/Nafion composite coating.

PubMed

Zeng, Jingbin; Chen, Jinmei; Song, Xinhong; Wang, Yiru; Ha, Jaeho; Chen, Xi; Wang, Xiaoru

2010-03-12

In this paper, we proposed an approach using a multi-walled carbon nanotubes (MWCNTs)/Nafion composite coating as a working electrode for the electrochemically enhanced solid-phase microextraction (EE-SPME) of charged compounds. Suitable negative and positive potentials were applied to enhance the extraction of cationic (protonated amines) and anionic compounds (deprotonated carboxylic acids) in aqueous solutions, respectively. Compared to the direct SPME mode (DI-SPME) (without applying potential), the EE-SPME presented more effective and selective extraction of charged analytes primarily via electrophoresis and complementary charge interaction. The experimental parameters relating to extraction efficiency of the EE-SPME such as applied potentials, extraction time, ionic strength, sample pH were studied and optimized. The linear dynamic range of developed EE-SPME-GC for the selected amines spanned three orders of magnitude (0.005-1mugmL(-1)) with R(2) larger than 0.9933, and the limits of detection were in the range of 0.048-0.070ngmL(-1). All of these characteristics demonstrate that the proposed MWCNTs/Nafion EE-SPME is an efficient, flexible and versatile sampling and extraction tool which is ideally suited for use with chromatographic methods. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Evaluation of solid-phase microextraction desorption parameters for fast GC analysis of cocaine in coca leaves.

PubMed

Ilias, Yara; Bieri, Stefan; Christen, Philippe; Veuthey, Jean-Luc

2006-08-01

By its simplicity and rapidity, solid-phase microextraction (SPME) appears as an interesting alternative for sample introduction in fast gas chromatography (fast GC). This combination depends on numerous parameters affecting the desorption step (i.e., the release of compounds from the SPME fiber coating to the GC column). In this study, different liner diameters, injection temperatures, and gas flow rates are evaluated to accelerate the thermal desorption process in the injection port. This process is followed with real-time direct coupling a split/splitless injector to a mass spectrometer by means of a short capillary. It is shown that an effective, quantitative, and rapid transfer of cocaine (COC) and cocaethylene (CE) is performed with a 0.75-mm i.d. liner, at 280 degrees C and 4 mL/min gas flow rate. The 7-microm polydimethylsiloxane (PDMS) coating is selected for combination with fast GC because the 100-microm PDMS fiber presents some limitations caused by fiber bleeding. Finally, the developed SPME-fast GC method is applied to perform in less than 5 min, the quantitation of COC extracted from coca leaves by focused microwave-assisted extraction. An amount of 7.6 +/- 0.5 mg of COC per gram of dry mass is found, which is in good agreement with previously published results.

Application of magnetic nanoparticles coated with sodium dodecyl sulfate and modified with 2-(5-bromo-2-pyridylazo)-5-diethyl aminophenol as a novel adsorbent for dispersive-magnetic solid-phase extraction and determination of palladium in soil samples.

PubMed

Wang, Meng; Wu, Lan; Hu, Qiufen; Yang, Yaling

2018-03-01

A rapid, sensitive, precise, and accurate dispersive-magnetic solid-phase extraction technique combined with flame atomic absorption spectrometry was established for pre-concentration and separation of Pd (II) in soil samples. In the developed system, 5-amine-1,10-phenanthroline was used as synergistic complexant; sodium dodecyl sulfate and 2-(5-bromo-2-pyridylazo)-5-diethyl aminophenol ligand coated on magnetic nanoparticles were synthesized by a chemical precipitation method, and then employed as the efficient magnetic adsorbent with good magnetic properties and dispersibility. Various operational parameters affecting the extraction efficiency has been studied and optimized in details. Under the optimum experimental conditions, the detection limit of the mentioned method for palladium ions was 0.12 μg/L, while the relative standard deviation was 1.8%. Finally, the developed method was applied for the analysis of palladium ions in three kinds of soil samples and quantitative recoveries were achieved over the range of 96.7-104.0%. It can be a powerful alternative applied to the determination of traces of Pd ions from various real samples in further researches.

Determination of five pyrethroids in tea drinks by dispersive solid phase extraction with polyaniline-coated magnetic particles.

PubMed

Wang, Yuanpeng; Sun, Ying; Gao, Yan; Xu, Bo; Wu, Qiong; Zhang, Hanqi; Song, Daqian

2014-02-01

The polyaniline-coated magnetic particles with bowl-shaped morphology (Fe3O4/C/PANI microbowls) were successfully prepared and characterized by scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. The prepared microbowls were used as the magnetic adsorbent in dispersive solid phase extraction of five pyrethroids, including cyhalothrin, beta-cypermethrin, esfenvalerate, permethrin and bifenthrin in plain tea drinks. The effects of experiment factors, including amount of Fe3O4/C/PANI microbowls, pH value, ultrasound extraction time and desorption conditions, were investigated. The extraction recoveries obtained with 8 mg of magnetic microbowls were satisfactory, and the microbowls can be reused after easy washing. Thus, a simple, selective and effective method for the determination of the pyrethroids was established successfully. The results showed that the method had good linearity (r=0.9992-0.9998), and the limits of detections (LODs) were from 0.025 to 0.032 ng mL(-1). The intra-day and inter-day relative standard deviations (RSDs) were in the range of 2.4-6.1% and 3.5-8.8%, respectively. Recoveries obtained by analyzing the real tea drinks were in the range of 72.1-118.4%. © 2013 Published by Elsevier B.V.

Charge transfer kinetics at the solid-solid interface in porous electrodes

NASA Astrophysics Data System (ADS)

Bai, Peng; Bazant, Martin Z.

2014-04-01

Interfacial charge transfer is widely assumed to obey the Butler-Volmer kinetics. For certain liquid-solid interfaces, the Marcus-Hush-Chidsey theory is more accurate and predictive, but it has not been applied to porous electrodes. Here we report a simple method to extract the charge transfer rates in carbon-coated LiFePO4 porous electrodes from chronoamperometry experiments, obtaining curved Tafel plots that contradict the Butler-Volmer equation but fit the Marcus-Hush-Chidsey prediction over a range of temperatures. The fitted reorganization energy matches the Born solvation energy for electron transfer from carbon to the iron redox site. The kinetics are thus limited by electron transfer at the solid-solid (carbon-LixFePO4) interface rather than by ion transfer at the liquid-solid interface, as previously assumed. The proposed experimental method generalizes Chidsey’s method for phase-transforming particles and porous electrodes, and the results show the need to incorporate Marcus kinetics in modelling batteries and other electrochemical systems.

Sol–gel method as a way of carbonyl iron powder surface modification for interaction improvement

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

Małecki, P., E-mail: pawel.malecki@pwr.edu.pl; Kolman, K.; Pigłowski, J.

2015-03-15

This article presents a method for modification of carbonyl iron particles’ surface (CIP), (d{sub 50}=4–9 µm) by silica coatings obtained using the sol–gel method. Reaction parameters were determined to obtain dry magnetic powder with homogeneous silica coatings without further processing and without any by-product in the solid or liquid phase. This approach is new among the commonly used methods of silica coating of iron particles. No attempt has been made to cover a carbonyl iron surface by silica in a waste-free method, up to date. In the current work two different silica core/shell structures were made by the sol–gel process,more » based on different silica precursors: tetraethoxy-silane (TEOS) and tetramethoxy-silane (TMOS). The dependence between the synthesis procedure and thickness of silica shell covering carbonyl iron particles has been described. Surface morphology of the modified magnetic particles and the coating thickness were characterized with the use of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Determination of the physicochemical structure of the obtained materials was performed by the energy-dispersive X-ray spectroscope (EDS), and the infrared technique (IR). The surface composition was analyzed using X-ray photoelectron spectroscopy (XPS). Additionally, distribution of particle size was measured using light microscopy. The new, efficient process of covering micro-size CIP with a nanometric silica layer was shown. Results of a performed analysis confirm the effectiveness of the presented method. - Highlights: • Proper covering CIP by sol–gel silica layer avoids agglomeration. • A new solid waste-free method of CIP coating is proposed. • Examination of the properties of modified CIP in depends on washing process. • Coatings on CIP particles doesn’t change the magnetic properties of particles.« less

Coating of peanuts with edible whey protein film containing alpha-tocopherol and ascorbyl palmitate.

PubMed

Han, J H; Hwang, H-M; Min, S; Krochta, J M

2008-10-01

Physical properties of whey protein isolate (WPI) coating solution incorporating ascorbic palmitate (AP) and alpha-tocopherol (tocopherol) were characterized, and the antioxidant activity of dried WPI coatings against lipid oxidation in roasted peanuts were investigated. The AP and tocopherol were mixed into a 10% (w/w) WPI solution containing 6.7% glycerol. Process 1 (P1) blended an AP and tocopherol mixture directly into the WPI solution using a high-speed homogenizer. Process 2 (P2) used ethanol as a solvent for dissolving AP and tocopherol into the WPI solution. The viscosity and turbidity of the WPI coating solution showed the Newtonian fluid behavior, and 0.25% of critical concentration of AP in WPI solution rheology. After peanuts were coated with WPI solutions, color changes of peanuts were measured during 16 wk of storage at 25 degrees C, and the oxidation of peanuts was determined by hexanal analysis using solid-phase micro-extraction samplers and GC-MS. Regardless of the presence of antioxidants in the coating layer, the formation of hexanal from the oxidation of peanut lipids was reduced by WPI coatings, which indicates WPI coatings protected the peanuts from oxygen permeation and oxidation. However, the incorporation of antioxidants in the WPI coating layer did not show a significant difference in hexanal production from that of WPI coating treatment without incorporation of antioxidants.

A novel sorbent based on carbon nanotube/amino-functionalized sol-gel for the headspace solid-phase microextraction of α-bisabolol from medicinal plant samples using experimental design.

PubMed

Yarazavi, Mina; Noroozian, Ebrahim

2018-02-13

A novel sol-gel coating on a stainless-steel fiber was developed for the first time for the headspace solid-phase microextraction and determination of α-bisabolol with gas chromatography and flame ionization detection. The parameters influencing the efficiency of solid-phase microextraction process, such as extraction time and temperature, pH, and ionic strength, were optimized by the experimental design method. Under optimized conditions, the linear range was between 0.0027 and 100 μg/mL. The relative standard deviations determined at 0.01 and 1.0 μg/mL concentration levels (n = 3), respectively, were as follows: intraday relative standard deviations 3.4 and 3.3%; interday relative standard deviations 5.0 and 4.3%; and fiber-to-fiber relative standard deviations 6.0 and 3.5%. The relative recovery values were 90.3 and 101.4% at 0.01 and 1.0 μg/mL spiking levels, respectively. The proposed method was successfully applied to various real samples containing α-bisabolol. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

76 FR 52867 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Adoption of Control...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-24

... coating solids, as applied] Baked Air dried Coating type Kilograms Pounds per per liter gallon (lb/ kg/l... per volume of coating solids, as applied] Baked Air dried Coating type kg/l lb/gal kg/l lb/gal General....3 lb/gal was revised to 3.34 lb/gal in the Baked--``General, One Component'' and ``General, Multi...

Solid lubricant behavior of MoS2 and WSe2-based nanocomposite coatings

PubMed Central

Domínguez-Meister, Santiago; Rojas, Teresa Cristina; Brizuela, Marta; Sánchez-López, Juan Carlos

2017-01-01

Abstract Tribological coatings made of MoS2 and WSe2 phases and their corresponding combinations with tungsten carbide (WC) were prepared by non-reactive magnetron sputtering of individual targets of similar composition. A comparative tribological analysis of these multiphase coatings was done in both ambient air (30–40% relative humidity, RH) and dry nitrogen (RH<7%) environments using the same tribometer and testing conditions. A nanostructural study using advanced transmission electron microscopy of the initial coatings and examination of the counterfaces after the friction test using different analytical tools helped to elucidate what governs the tribological behavior for each type of environment. This allowed conclusions to be made about the influence of the coating microstructure and composition on the tribological response. The best performance obtained with a WSex film (specific wear rate of 2 × 10−8 mm3 N–1m–1 and a friction coefficient of 0.03–0.05) was compared with that of the well-established MoS2 lubricant material. PMID:28458736

Solid-phase microextraction and chiral HPLC analysis of ibuprofen in urine.

PubMed

de Oliveira, Anderson Rodrigo Moraes; Cesarino, Evandro José; Bonato, Pierina Sueli

2005-04-25

A simple and rapid solid-phase microextraction method was developed for the enantioselective analysis of ibuprofen in urine. The sampling was made with a polydimethylsiloxane-divinylbenzene coated fiber immersed in the liquid sample. After desorptioning from the fiber, ibuprofen enantiomers were analyzed by HPLC using a Chiralpak AD-RH column and UV detection. The mobile phase was made of methanol-pH 3.0 phosphoric acid solution (75:25, v/v), at a flow rate of 0.45 mL/min. The mean recoveries of SPME were 19.8 and 19.1% for (-)-R-ibuprofen and (+)-(S)-ibuprofen, respectively. The method was linear at the range of 0.25-25 microg/mL. Within-day and between-day assay precision and accuracy were below 15% for both ibuprofen enantiomers at concentrations of 0.75, 7.5 and 20 microg/mL. The method was tested with urine quality control samples and human urine fractions after administration of 200 mg rac-ibuprofen.

Determination of some aldehydes by using solid-phase microextraction and high-performance liquid chromatography with UV detection.

PubMed

Kumar, Ashwini; Singh, Baldev; Malik, Ashok Kumar; Tiwary, Dhananjay K

2007-01-01

A new approach has been developed for the extraction and determination of aldehydes such as veratraldehyde, m-nitrobenzaldehyde, cinnamaldehyde, benzaldehyde, and p-chlorobenzaldehyde by using solid-phase microextraction (SPME) and high-performance liquid chromatography with UV detection (HPLC/UV). The method involves adsorption of the aldehydes on polydimethylsiloxane/divinylbenzene-coated fiber, followed by desorption in the desorption chamber of the SPME-HPLC interface, using acetonitrile-water (70 + 30) as the mobile phase; UV detection was at 254 nm. A good separation of 5 aldehydes was obtained on a C18 column. The detection limits of veratraldehyde, m-nitrobenzaldehyde, cinnamaldehyde, benzaldehyde, and p-chlorobenzaldehyde are 25, 41, 13, 12, and 11 pg/mL, respectively, which are about 100 times better than the detection limits for other SPME methods using gas chromatography. The proposed method was validated by determining benzaldehyde in bitter almonds and cinnamaldehyde in cinnamon bark. The recoveries of the 5 analytes were determined by analysis of spiked drinking water.

40 CFR 721.10636 - Slimes and sludges, automotive coating, wastewater treatment, solid waste.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., wastewater treatment, solid waste. 721.10636 Section 721.10636 Protection of Environment ENVIRONMENTAL..., wastewater treatment, solid waste. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as slimes and sludges, automotive coating, wastewater treatment...

40 CFR 721.10636 - Slimes and sludges, automotive coating, wastewater treatment, solid waste.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., wastewater treatment, solid waste. 721.10636 Section 721.10636 Protection of Environment ENVIRONMENTAL..., wastewater treatment, solid waste. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as slimes and sludges, automotive coating, wastewater treatment...

Solvent vapour monitoring in work space by solid phase micro extraction.

PubMed

Li, K; Santilli, A; Goldthorp, M; Whiticar, S; Lambert, P; Fingas, M

2001-05-07

Solid phase micro extraction (SPME) is a fast, solvent-less alternative to conventional charcoal tube sampling/carbon disulfide extraction for volatile organic compounds (VOC). In this work, SPME was compared to the active sampling technique in a typical lab atmosphere. Two different types of fibre coatings were evaluated for solvent vapour at ambient concentration. A general purpose 100 microm film polydimethylsiloxane (PDMS) fibre was found to be unsuitable for VOC work, despite the thick coating. The mixed-phase carboxen/PDMS fibre was found to be suitable. Sensitivity of the SPME was far greater than charcoal sorbent tube method. Calibration studies using typical solvent such as dichloromethane (DCM), benzene (B) and toluene (T) showed an optimal exposure time of 5 min, with a repeatability of less than 20% for a broad spectrum of organic vapour. Minimum detectable amount for DCM is in the range of 0.01 microg/l (0.003 ppmv). Variation among different fibres was generally within 30% at a vapour concentration of 1 microg DCM/l, which was more than adequate for field monitoring purpose. Adsorption characteristics and calibration procedures were studied. An actual application of SPME was carried out to measure background level of solvent vapour at a bench where DCM was used extensively. Agreement between the SPME and the charcoal sampling method was generally within a factor of two. No DCM concentration was found to be above the regulatory limit of 50 ppmv.

Determination of nitrate esters in water samples Comparison of efficiency of solid-phase extraction and solid-phase microextraction.

PubMed

Jezová, Vera; Skládal, Jan; Eisner, Ales; Bajerová, Petra; Ventura, Karel

2007-12-07

This paper deals with comparison of efficiency of extraction techniques (solid-phase extraction, SPE and solid-phase microextraction, SPME) used for extraction of nitrate esters (ethyleneglycoldinitrate, EGDN and nitroglycerin, NG), representing the first step of the method of quantitative determination of trace concentrations of nitrate esters in water samples. EGDN and NG are subsequently determined by means of high-performance liquid chromatography with ultraviolet detection (HPLC-UV). Optimization of SPE and SPME conditions was carried out using model water samples. Seven SPE cartridges were tested and the conditions were optimized (type of sorbent, type and volume of solvent to be used as eluent). For both nitrate esters the limit of detection (LOD) and the limit of quantification (LOQ) obtained using SPE/HPLC-UV were 0.23 microg mL(-1) and 0.70 microg mL(-1), respectively. Optimization of SPME conditions: type of SPME fibre (four fibres were tested), type and time of sorption/desorption, temperature of sorption. PDMS/DVB (polydimethylsiloxane/divinylbenzene) fibre coating proved to be suitable for extraction of EGDN and NG. For this fibre the LOD and the LOQ for both nitrate esters were 0.16 microg mL(-1) and 0.50 microg mL(-1), respectively. Optimized methods SPE/HPLC-UV and SPME/HPLC-UV were then used for quantitative determination of nitrate esters content in real water samples from the production of EGDN and NG.

Development of a sensitive methodology for the analysis of chlorobenzenes in air by combination of solid-phase extraction and headspace solid-phase microextraction.

PubMed

Barro, Ruth; Ares, Sergio; Garcia-Jares, Carmen; Llompart, Maria; Cela, Rafael

2004-08-06

In this study, a combination of solid-phase extraction (SPE) and solid-phase microextraction (SPME) has been used to determine chlorobenzenes in air. Analytes were sampled by pumping a known volume of air through a porous polymer (Tenax TA). Then, the adsorbent was transferred into a glass vial and SPME was performed. The quantification was carried out using gas chromatography (GC)-electron-capture detection or GC-MS. Several SPME coatings (100 microm poly(dimethylsiloxane) (PDMS), 75 microm Carboxen (CAR)-PDMS, 65 microm PDMS-divinylbenzene (DVB), 65 microm PDMS-DVB and 85 microm polyacrylate (PA) were evaluated, obtaining the highest responses with Carbowax (CW)- PDMS for the most volatile chlorobenzenes, and with PDMS-DVB or CW-DVB fibers for the semivolatile compounds. To optimize some other factors that could affect the SPME step, a factorial design was used. Kinetic studies of the SPME process were also performed. Concerning the SPE step, breakthrough was studied, showing that 2.5 m3 of air could be processed without losses of the most volatile compounds. The performance of the method was evaluated. External calibration, which does not require the complete sampling process, demonstrated to be suitable, obtaining good linearity (R2 > 0.99) for all chlorobenzenes. Recovery studies were performed at two concentration levels (4 and 40 ng/m3), obtaining quantitative recoveries (>80%). Limits of detection at the sub ng/m3 were achieved for all the target compounds.

Determination of 1,3-dichloro-2-propanol and 3-chloro-1,2-propandiol in soy sauce by headspace derivatization solid-phase microextraction combined with gas chromatography-mass spectrometry.

PubMed

Lee, Maw-Rong; Chiu, Tzu-Chun; Dou, Jianpeng

2007-05-22

This study proposes a method for identifying 1,3-dichloro-2-propanol and 3-chloro-1,2-propandiol in aqueous matrices by using headspace on-fiber derivatization following solid-phase microextraction combined with gas chromatography-mass spectrometry. The optimized SPME experimental procedures for extracting 1,3-dichloro-2-propanol and 3-chloro-1,2-propandiol in aqueous solutions involved a 85 microm polyacrylate-coated fiber at pH 6, a sodium chloride concentration of 0.36 g mL(-1), extraction at 50 degrees C for 15 min and desorption of analytes at 260 degrees C for 3 min. Headspace derivatization was conducted in a laboratory-made design with N-methyl-N-(trimethylsilyl)-trifluoroacetamide vapor following solid-phase microextraction by using 3 microL N-methyl-N-(trimethylsilyl)-trifluoroacetamide at an oil bath temperature of 230 degrees C for 40 s. This method had good repeatability (R.S.D.s < or = 19%, n = 8) and good linearity (r2 > or = 0.9972) for ultrapure water and soy sauce samples that were spiked with two analytes. Detection limits were obtained at the ng mL(-1). The result demonstrated that headspace on-fiber derivatization following solid-phase microextraction was a simple, fast and accurate technique for identifying trace 1,3-dichloro-2-propanol and 3-chloro-1,2-propandiol in soy sauce.

Comparison of HPMC based polymers performance as carriers for manufacture of solid dispersions using the melt extruder.

PubMed

Ghosh, Indrajit; Snyder, Jennifer; Vippagunta, Radha; Alvine, Marilyn; Vakil, Ronak; Tong, Wei-Qin; Vippagunta, Sudha

2011-10-31

Preparation of amorphous solid dispersions using hot-melt extrusion process for poorly water soluble compounds which degrade on melting remains a challenge due to exposure to high temperatures. The aim of this study was to develop a physically and chemically stable amorphous solid dispersion of a poorly water-soluble compound, NVS981, which is highly thermal sensitive and degrades upon melting at 165 °C. Hydroxypropyl Methyl Cellulose (HPMC) based polymers; HPMC 3cps, HPMC phthalate (HPMCP) and HPMC acetyl succinate (HPMCAS) were selected as carriers to prepare solid dispersions using hot melt extrusion because of their relatively low glass transition temperatures. The solid dispersions were compared for their ease of manufacturing, physical stability such as recrystallization potential, phase separation, molecular mobility and enhancement of drug dissolution. Two different drug loads of 20 and 50% (w/w) were studied in each polymer system. It was interesting to note that solid dispersions with 50% (w/w) drug load were easier to process in the melt extruder compared to 20% (w/w) drug load in all three carriers, which was attributed to the plasticizing behavior of the drug substance. Upon storage at accelerated stability conditions, no phase separation was observed in HPMC 3cps and HPMCAS solid dispersions at the lower and higher drug load, whereas for HPMCP, phase separation was observed at higher drug load after 3 months. The pharmaceutical performance of these solid dispersions was evaluated by studying drug dissolution in pH 6.8 phosphate buffer. Drug release from solid dispersion prepared from polymers used for enteric coating, i.e. HPMCP and HPMCAS was faster compared with the water soluble polymer HPMC 3cps. In conclusion, of the 3 polymers studied for preparing solid dispersions of thermally sensitive compound using hot melt extrusion, HPMCAS was found to be the most promising as it was easily processible and provided stable solid dispersions with enhanced dissolution. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of Particle Morphology on Cold Spray Deposition of Chromium Carbide-Nickel Chromium Cermet Powders

NASA Astrophysics Data System (ADS)

Fernandez, Ruben; Jodoin, Bertrand

2017-08-01

Nickel chromium-chromium carbide coatings provide good corrosion and wear resistance at high temperatures, making them ideal for applications where a harsh environment and high temperatures are expected. Thermal spray processes are preferred as deposition technique of cermets, but the high process temperatures can lead to decarburization and reduction of the coatings properties. Cold spray uses lower temperatures preventing decarburization. Since the metallic phase remains solid, the feedstock powder morphology becomes crucial on the deposition behavior. Six commercially available powders were studied, varying in morphology and metal/ceramic ratios. The powders were categorized into 4 groups depending on their morphology. Spherical powders lead to substrate erosion due to their limited overall ductility. Porous agglomerated and sintered powders lead to severely cracked coatings. For dense agglomerated and sintered powders, the outcome depended on the initial metal/ceramic ratio: powders with 25 wt.% NiCr led to substrate erosion while 35 wt.% NiCr powders led to dense coatings. Finally, blended ceramic-metal mixtures also lead to dense coatings. All coatings obtained had lower ceramic content than the initial feedstock powders. Interrupted spray tests, combined with FEA, helped drawing conclusions on the deposition behavior to explain the obtained results.

Photo-acoustic excitation and detection of guided ultrasonic waves in bone samples covered by a soft coating layer

NASA Astrophysics Data System (ADS)

Zhao, Zuomin; Moilanen, Petro; Karppinen, Pasi; Määttä, Mikko; Karppinen, Timo; Hæggström, Edward; Timonen, Jussi; Myllylä, Risto

2012-12-01

Photo-acoustic (PA) excitation was combined with skeletal quantitative ultrasound (QUS) for multi-mode ultrasonic assessment of human long bones. This approach permits tailoring of the ultrasonic excitation and detection so as to efficiently detect the fundamental flexural guided wave (FFGW) through a coating of soft tissue. FFGW is a clinically relevant indicator of cortical thickness. An OPO laser with tunable optical wavelength, was used to excite a photo-acoustic source in the shaft of a porcine femur. Ultrasonic signals were detected by a piezoelectric transducer, scanning along the long axis of the bone, 20-50 mm away from the source. Five femurs were measured without and with a soft coating. The coating was made of an aqueous gelatin-intralipid suspension that optically and acoustically mimicked real soft tissue. An even coating thickness was ensured by using a specific mold. The optical wave length of the source (1250 nm) was tuned to maximize the amplitude of FFGW excitation at 50 kHz frequency. The experimentally determined FFGW phase velocity in the uncoated samples was consistent with that of the fundamental antisymmetric Lamb mode (A0). Using appropriate signal processing, FFGW was also identified in the coated bone samples, this time with a phase velocity consistent with that theoretically predicted for the first mode of a fluid-solid bilayer waveguide (BL1). Our results suggest that photo-acoustic quantitative ultrasound enables assessment of the thickness-sensitive FFGW in bone through a layer of soft tissue. Photo-acoustic characterization of the cortical bone thickness may thus become possible.

Anodized porous titanium coated with Ni-CeO2 deposits for enhancing surface toughness and wear resistance

NASA Astrophysics Data System (ADS)

Zhou, Xiaowei; Ouyang, Chun

2017-05-01

In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO2 nanocomposite coatings. Regarding TiO2 barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO2 deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO2 nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO2 nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devoted to comparing different wear behaviors of Ni-CeO2 coatings relative to pure nickel. Results indicated that uniform-distributed Ti nanopores with an average diameter size of ∼200 nm was achieved using the Phosphate-type anodizing solution at DC 150 V. A worn surface without fatigue cracks was observed for TAO surface coated with Ni-CeO2 deposits, showing the existing Ce-rich worn products to be acted as a solid lubricant phase for making a self-healing effect on de-lamination failures. More important, this finding will be the guidelines for Ce-rich precipitations to be expected as the strengthening phase in anodized porous of Ti, Al and Mg alloys for intensifying their surface properties.

Rapid, cool sintering of wet processed yttria-stabilized zirconia ceramic electrolyte thin films.

PubMed

Park, Jun-Sik; Kim, Dug-Joong; Chung, Wan-Ho; Lim, Yonghyun; Kim, Hak-Sung; Kim, Young-Beom

2017-09-29

Here we report a photonic annealing process for yttria-stabilized zirconia films, which are one of the most well-known solid-state electrolytes for solid oxide fuel cells (SOFCs). Precursor films were coated using a wet-chemical method with a simple metal-organic precursor solution and directly annealed at standard pressure and temperature by two cycles of xenon flash lamp irradiation. The residual organics were almost completely decomposed in the first pre-annealing step, and the fluorite crystalline phases and good ionic conductivity were developed during the second annealing step. These films showed properties comparable to those of thermally annealed films. This process is much faster than conventional annealing processes (e.g. halogen furnaces); a few seconds compared to tens of hours, respectively. The significance of this work includes the treatment of solid-state electrolyte oxides for SOFCs and the demonstration of the feasibility of other oxide components for solid-state energy devices.

Optimisation of gellan gum edible coating for ready-to-eat mango (Mangifera indica L.) bars.

PubMed

Danalache, Florina; Carvalho, Claudia Y; Alves, Vitor D; Moldão-Martins, Margarida; Mata, Paulina

2016-03-01

The optimisation of an edible coating based on low acyl (L)/high acyl (H) gellan gum for ready-to-eat mango bars was performed through a central composite rotatable design (CCRD). The independent variables were the concentration of gellan (L/H90/10) and the concentration of Ca(2+) in the coating solution, as well as the storage time after coating application. The response variables studied were the coating thickness, mango bars firmness, syneresis, and colour alterations. Gellan concentration was the independent variable that most influenced the thickness of the coating. Syneresis was quite low for the conditions tested (<1.64%). Similarly, the colour alterations were low during the entire storage time (ΔE<5). Considering the model predictions, 1.0%wt L/H90/10 with addition of 6 mM Ca(2+) could represent the optimal coating formulation for the mango bars. The release of eight volatile compounds from the uncoated and coated mango bars with the selected formulation was analysed by Headspace - Solid Phase Micro Extraction-Gas Chromatography during 9 days of refrigerated storage. This work showed that the coating can improve mango bars sensory characteristics (appearance and firmness) and stability in terms of syneresis, colour and volatiles content during storage increasing the commercial value of the final product. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Solid lubricant materials for high temperatures: A review

NASA Technical Reports Server (NTRS)

Sliney, Harold E.

1985-01-01

Solid lubricants that can be used above 300 C in air are discussed, including coatings and self-lubricating composite bearing materials. The lubricants considered are representative dichalcogenides, graphite, graphite fluoride, polyimides, soft oxides, oxidatively stable fluorides, and hard coating materials. A few general design considerations revelant to solid lubrication are interspersed.

Microstructure and wear resistance of Al2O3-M7C3/Fe composite coatings produced by laser controlled reactive synthesis

NASA Astrophysics Data System (ADS)

Tan, Hui; Luo, Zhen; Li, Yang; Yan, Fuyu; Duan, Rui

2015-05-01

Based on the principle of thermite reaction of Al and Fe2O3 powders, the Al2O3 ceramic reinforced Fe-based composite coatings were fabricated on a steel substrate by laser controlled reactive synthesis and cladding. The effects of different additions of thermite reactants on the phase transition, microstructure evolution, microhardness and wear resistance of the composite coatings were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Vickers microhardness and block-on-ring wear test, respectively. The results show that Al2O3 ceramic and M7C3 carbide are in situ synthesized via the laser controlled reactive synthesis. The Al2O3 ceramic and M7C3 carbides prefer to distribute along the γ-Fe phase boundary continuously, which separates the γ-Fe matrix and is beneficial to the grain refinement. With the increase of thermite reactants, the amount of Al2O3 ceramic and M7C3 carbide in the composite coatings increases gradually. Moreover the cladding layer changes from dendritic structure to columnar structure and martensite structure in the heat affected zone becomes coarse. The increased thermite reactants improve the microhardness and wear resistance of the in situ composite coatings obviously and enhance the hardness of the heat affected zone, which should be ascribed to the grain refinement, ceramic and carbide precipitation and solid solution strengthening.

The Effect of Journal Roughness and Foil Coatings on the Performance of Heavily Loaded Foil Air Bearings

NASA Technical Reports Server (NTRS)

Radil, Kevin C.; DellaCorte, Christopher

2001-01-01

Foil air bearing load capacity tests were conducted to investigate if a solid lubricant coating applied to the surface of the bearing's top foil can function as a break-in coating. Two foil coating materials, a conventional soft polymer film (polyimide) and a hard ceramic (alumina), were independently evaluated against as-ground and worn (run-in) journals coated with NASA PS304, a high-temperature solid lubricant composite coating. The foil coatings were evaluated at journal rotational speeds of 30,000 rpm and at 25 C. Tests were also performed on a foil bearing with a bare (uncoated) nickel-based superalloy top foil to establish a baseline for comparison. The test results indicate that the presence of a top foil solid lubricant coating is effective at increasing the load capacity performance of the foil bearing. Compared to the uncoated baseline, the addition of the soft polymer coating on the top foil increased the bearing load coefficient by 120% when operating against an as-ground journal surface and 85 percent against a run-in journal surface. The alumina coating increased the load coefficient by 40% against the as-ground journal but did not have any affect when the bearing was operated with the run-in journal. The results suggest that the addition of solid lubricant films provide added lubrication when the air film is marginal indicating that as the load capacity is approached foil air bearings transition from hydrodynamic to mixed and boundary lubrication.

High Power Diode Laser-Treated HP-HVOF and Twin Wire Arc-Sprayed Coatings for Fossil Fuel Power Plants

NASA Astrophysics Data System (ADS)

Mann, B. S.

2013-08-01

This article deals with high power diode laser (HPDL) surface modification of twin wire arc-sprayed (TWAS) and high pressure high velocity oxy-fuel (HP-HVOF) coatings to combat solid particle erosion occurring in fossil fuel power plants. To overcome solid particle impact wear above 673 K, Cr3C2-NiCr-, Cr3C2-CoNiCrAlY-, and WC-CrC-Ni-based HVOF coatings are used. WC-CoCr-based HVOF coatings are generally used below 673 K. Twin wire arc (TWA) spraying of Tafa 140 MXC and SHS 7170 cored wires is used for a wide range of applications for a temperature up to 1073 K. Laser surface modification of high chromium stainless steels for steam valve components and LPST blades is carried out regularly. TWA spraying using SHS 7170 cored wire, HP-HVOF coating using WC-CoCr powder, Ti6Al4V alloy, and high chromium stainless steels (X20Cr13, AISI 410, X10CrNiMoV1222, 13Cr4Ni, 17Cr4Ni) were selected in the present study. Using robotically controlled parameters, HPDL surface treatments of TWAS-coated high strength X10CrNiMoV1222 stainless steel and HP-HVOF-coated AISI 410 stainless steel samples were carried out and these were compared with HPDL-treated high chromium stainless steels and titanium alloy for high energy particle impact wear (HEPIW) resistance. The HPDL surface treatment of the coatings has improved the HEPIW resistance manifold. The improvement in HPDL-treated stainless steels and titanium alloys is marginal and it is not comparable with that of HPDL-treated coatings. These coatings were also compared with "as-sprayed" coatings for fracture toughness, microhardness, microstructure, and phase analyses. The HEPIW resistance has a strong relationship with the product of fracture toughness and microhardness of the HPDL-treated HP-HVOF and TWAS SHS 7170 coatings. This development opens up a possibility of using HPDL surface treatments in specialized areas where the problem of HEPIW is very severe. The HEPIW resistance of HPDL-treated high chromium stainless steels and titanium alloys, HPDL-treated TWAS SHS 7170 and HP-HVOF coatings, and their micrographs and X-ray diffraction analysis is reported in this article.

MCrAlY bond coat with enhanced Yttrium layer

DOEpatents

Jablonski, Paul D; Hawk, Jeffrey A

2015-04-21

One or more embodiments relates to an MCrAlY bond coat comprising an MCrAlY layer in contact with a Y--Al.sub.2O.sub.3 layer. The MCrAlY layer is comprised of a .gamma.-M solid solution, a .beta.-MAl intermetallic phase, and Y-type intermetallics. The Y--Al.sub.2O.sub.3 layer is comprised of Yttrium atoms coordinated with oxygen atoms comprising the Al.sub.2O.sub.3 lattice. Both the MCrAlY layer and the Y--Al.sub.2O.sub.3 layer have a substantial absence of Y--Al oxides, providing advantage in the maintainability of the Yttrium reservoir within the MCrAlY bulk. The MCrAlY bond coat may be fabricated through application of a Y.sub.2O.sub.3 paste to an MCrAlY material, followed by heating in a non-oxidizing environment.

Enhanced Physical Stability of Amorphous Drug Formulations via Dry Polymer Coating.

PubMed

Capece, Maxx; Davé, Rajesh

2015-06-01

Although amorphous solid drug formulations may be advantageous for enhancing the bioavailability of poorly soluble active pharmaceutical ingredients, they exhibit poor physical stability and undergo recrystallization. To address this limitation, this study investigates stability issues associated with amorphous solids through analysis of the crystallization behavior for acetaminophen (APAP), known as a fast crystallizer, using a modified form of the Avrami equation that kinetically models both surface and bulk crystallization. It is found that surface-enhanced crystallization, occurring faster at the free surface than in the bulk, is the major impediment to the stability of amorphous APAP. It is hypothesized that a novel use of a dry-polymer-coating process referred to as mechanical-dry-polymer-coating may be used to inhibit surface crystallization and enhance stability. The proposed process, which is examined, simultaneously mills and coats amorphous solids with polymer, while avoiding solvents or solutions, which may otherwise cause stability or crystallization issues during coating. It is shown that solid dispersions of APAP (64% loading) with a small particle size (28 μm) could be prepared and coated with the polymer, carnauba wax, in a vibratory ball mill. The resulting amorphous solid was found to have excellent stability as a result of inhibition of surface crystallization. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

A Systems Approach to the Solid Lubrication of Foil Air Bearings for Oil-Free Turbomachinery

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Zaldana, Antonio R.; Radil, Kevin C.

2002-01-01

Foil air bearings are self-acting hydrodynamic bearings which rely upon solid lubricants to reduce friction and minimize wear during sliding which occurs at start-up and shut-down when surface speeds are too low to allow the formation of a hydrodynamic air film. This solid lubrication is typically accomplished by coating the non-moving foil surface with a thin, soft polymeric film. The following paper introduces a systems approach in which the solid lubrication is provided by a combination of self lubricating shaft coatings coupled with various wear resistant and lubricating foil coatings. The use of multiple materials, each providing different functions is modeled after oil-lubricated hydrodynamic sleeve bearing technology which utilizes various coatings and surface treatments in conjunction with oil lubricants to achieve optimum performance. In this study, room temperature load capacity tests are performed on journal foil air bearings operating at 14,000 rpm. Different shaft and foil coating technologies such as plasma sprayed composites, ceramic, polymer and inorganic lubricant coatings are evaluated as foil bearing lubricants. The results indicate that bearing performance is improved through the individual use of the lubricants and treatments tested. Further, combining several solid lubricants together yielded synergistically better results than any material alone.

Microstructure characteristics of Ni/WC composite cladding coatings

NASA Astrophysics Data System (ADS)

Yang, Gui-rong; Huang, Chao-peng; Song, Wen-ming; Li, Jian; Lu, Jin-jun; Ma, Ying; Hao, Yuan

2016-02-01

A multilayer tungsten carbide particle (WCp)-reinforced Ni-based alloy coating was fabricated on a steel substrate using vacuum cladding technology. The morphology, microstructure, and formation mechanism of the coating were studied and discussed in different zones. The microstructure morphology and phase composition were investigated by scanning electron microscopy, optical microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. In the results, the coating presents a dense and homogeneous microstructure with few pores and is free from cracks. The whole coating shows a multilayer structure, including composite, transition, fusion, and diffusion-affected layers. Metallurgical bonding was achieved between the coating and substrate because of the formation of the fusion and diffusion-affected layers. The Ni-based alloy is mainly composed of γ-Ni solid solution with finely dispersed Cr7C3/Cr23C6, CrB, and Ni+Ni3Si. WC particles in the composite layer distribute evenly in areas among initial Ni-based alloying particles, forming a special three-dimensional reticular microstructure. The macrohardness of the coating is HRC 55, which is remarkably improved compared to that of the substrate. The microhardness increases gradually from the substrate to the composite zone, whereas the microhardness remains almost unchanged in the transition and composite zones.

Terahertz pulsed imaging as an advanced characterisation tool for film coatings--a review.

PubMed

Haaser, Miriam; Gordon, Keith C; Strachan, Clare J; Rades, Thomas

2013-12-05

Solid dosage forms are the pharmaceutical drug delivery systems of choice for oral drug delivery. These solid dosage forms are often coated to modify the physico-chemical properties of the active pharmaceutical ingredients (APIs), in particular to alter release kinetics. Since the product performance of coated dosage forms is a function of their critical coating attributes, including coating thickness, uniformity, and density, more advanced quality control techniques than weight gain are required. A recently introduced non-destructive method to quantitatively characterise coating quality is terahertz pulsed imaging (TPI). The ability of terahertz radiation to penetrate many pharmaceutical materials enables structural features of coated solid dosage forms to be probed at depth, which is not readily achievable with other established imaging techniques, e.g. near-infrared (NIR) and Raman spectroscopy. In this review TPI is introduced and various applications of the technique in pharmaceutical coating analysis are discussed. These include evaluation of coating thickness, uniformity, surface morphology, density, defects and buried structures as well as correlation between TPI measurements and drug release performance, coating process monitoring and scale up. Furthermore, challenges and limitations of the technique are discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Solid-phase microextraction coupled with high-performance liquid chromatography for the determination of phenylurea herbicides in aqueous samples.

PubMed

Lin, Hsin-Hang; Sung, Yu-Hsiang; Huang, Shang-Da

2003-09-12

Solid-phase microextraction coupled with high-performance liquid chromatography was successfully applied to the analysis of nine phenylurea herbicides (metoxuron, monuron, chlorotoluron, isoproturon, monolinuron, metobromuron, buturon, linuron, and chlorbromuron). Polydimethylsiloxane-divinylbenzene (PDMS-DVB, 60 microm) and Carbowax-templated resin (CW-TPR, 50 microm) fibers were selected from four commercial fibers for further study because of their better extraction efficiencies. The parameters of the desorption procedure were studied and optimized. The effects of the properties of analytes and fiber coatings, carryover, duration and temperature of absorption, pH, organic solvent and ionic strength of samples were also investigated. External calibration with an aqueous standard can be used for the analysis of environmental samples (lake water) using either PDMS-DVB or CW-TPR fibers. Good precisions (1.0-5.9%) are achieved for this method, and the detection limits are at the level of 0.5-5.1 ng/ml.

Coupling solid-phase microextraction and high-performance liquid chromatography for direct and sensitive determination of halogenated fungicides in wine.

PubMed

Millán, S; Sampedro, M C; Unceta, N; Goicolea, M A; Rodríguez, E; Barrio, R J

2003-05-02

A solid-phase microextraction (SPME) method coupled to high-performance liquid chromatography with diode array detection (HPLC-DAD) for the analysis of six organochlorine fungicides (nuarimol, triadimenol, triadimefon, folpet, vinclozolin and penconazole) in wine was developed. For this purpose, polydimethylsiloxane-divinylbenzene-coated fibers were utilized and all factors affecting throughput, precision, and accuracy of the SPME method were investigated and optimized. These factors include: matrix influence, extraction and desorption time, percentage of ethanol, pH, salt effect and desorption mode. The performed analytical procedure showed detectability ranging from 4 to 27 microg l(-1) and precision from 2.4 to 14.2% (as intra-day relative standard deviation, RSD) and 4.7-25.7% (as inter-day RSD) depending on the fungicide. The results demonstrate the suitability of the SPME-HPLC-DAD method to analyze these organochlorine fungicides in red wine.

Coherent diffractive imaging of solid state reactions in zinc oxide crystals

NASA Astrophysics Data System (ADS)

Leake, Steven J.; Harder, Ross; Robinson, Ian K.

2011-11-01

We investigated the doping of zinc oxide (ZnO) microcrystals with iron and nickel via in situ coherent x-ray diffractive imaging (CXDI) in vacuum. Evaporated thin metal films were deposited onto the ZnO microcrystals. A single crystal was selected and tracked through annealing cycles. A solid state reaction was observed in both iron and nickel experiments using CXDI. A combination of the shrink wrap and guided hybrid-input-output phasing methods were applied to retrieve the electron density. The resolution was 33 nm (half order) determined via the phase retrieval transfer function. The resulting images are nevertheless sensitive to sub-angstrom displacements. The exterior of the microcrystal was found to degrade dramatically. The annealing of ZnO microcrystals coated with metal thin films proved an unsuitable doping method. In addition the observed defect structure of one crystal was attributed to the presence of an array of defects and was found to change upon annealing.

Determination of volatile monophenols in beer using acetylation and headspace solid-phase microextraction in combination with gas chromatography and mass spectrometry.

PubMed

Sterckx, Femke L; Saison, Daan; Delvaux, Freddy R

2010-08-31

Monophenols are widely spread compounds contributing to the flavour of many foods and beverages. They are most likely present in beer, but so far, little is known about their influence on beer flavour. To quantify these monophenols in beer, we optimised a headspace solid-phase microextraction method coupled to gas chromatography-mass spectrometry. To improve their isolation from the beer matrix and their chromatographic properties, the monophenols were acetylated using acetic anhydride and KHCO(3) as derivatising agent and base catalyst, respectively. Derivatisation conditions were optimised with attention for the pH of the reaction medium. Additionally, different parameters affecting extraction efficiency were optimised, including fibre coating, extraction time and temperature and salt addition. Afterwards, we calibrated and validated the method successfully and applied it for the analysis of monophenols in beer samples. 2010 Elsevier B.V. All rights reserved.

Surface-modified multifunctional MIP nanoparticles.

PubMed

Moczko, Ewa; Poma, Alessandro; Guerreiro, Antonio; Perez de Vargas Sansalvador, Isabel; Caygill, Sarah; Canfarotta, Francesco; Whitcombe, Michael J; Piletsky, Sergey

2013-05-07

The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as a protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity (PEG methacrylate); electro-activity (vinylferrocene); fluorescence (eosin acrylate); thiol groups (pentaerythritol tetrakis(3-mercaptopropionate)). The method has broad applicability and can be used to produce multifunctional imprinted nanoparticles with potential for further application in the biosensors, diagnostics and biomedical fields and as an alternative to natural receptors.

Mixed hemimicelles solid-phase extraction based on ionic liquid-coated Fe3O4/SiO2 nanoparticles for the determination of flavonoids in bio-matrix samples coupled with high performance liquid chromatography.

PubMed

He, Huan; Yuan, Danhua; Gao, Zhanqi; Xiao, Deli; He, Hua; Dai, Hao; Peng, Jun; Li, Nan

2014-01-10

A novel magnetic solid-phase extraction (MSPE) method based on mixed hemimicelles of room temperature ionic liquids (RTILs) coated Fe3O4/SiO2 nanoparticles (NPs) was developed for simultaneous extraction of trace amounts of flavonoids in bio-matrix samples. A comparative study on the use of RTILs (C16mimBr) and CTAB-coated Fe3O4/SiO2 NPs as sorbents was presented. Owing to bigger adsorption amounts for analytes, RTILs-coated Fe3O4/SiO2 NPs was selected as MSPE materials and three analytes luteolin, quercetin and kaempferol can be quantitatively extracted and simultaneously determined coupled with high performance liquid chromatography (HPLC) in urine samples. No interferences were caused by proteins or endogenous compounds. Good linearity (R(2)>0.9993) for all calibration curves was obtained, and the limits of detection (LOD) for luteolin, quercetin and kaempferol were 0.10 ng/mL, 0.50 ng/mL and 0.20 ng/mL in urine samples, respectively. Satisfactory recoveries (93.5-97.6%, 90.1-95.4% and 93.3-96.6% for luteolin, quercetin and kaempferol) in biological matrices were achieved. It was notable that while using a small amount of Fe3O4/SiO2 NPs (4.0 mg) and C16mimBr (1.0 mg), satisfactory preconcentration factors and extraction recoveries for the three flavonoids were obtained. To the best of our knowledge, this is the first time a mixed hemimicelles MSPE method based on RTILs and Fe3O4/SiO2 NPs magnetic separation has ever been used for pretreatment of complex biological samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Ultra small angle x-ray scattering in complex mixtures of triacylglycerols

NASA Astrophysics Data System (ADS)

Peyronel, Fernanda; Quinn, Bonnie; Marangoni, Alejandro G.; Pink, David A.

2014-11-01

Ultra-small angle x-ray scattering (USAXS) has been used to elucidate, in situ, the aggregation structure of unsheared model edible oils. Each system comprised one or two solid lipids and a combination of liquid lipids. The 3D nano- to micro-structures of each system were characterized. The length scale investigated, using the Bonse-Hart camera at beamline ID-15D at the Advanced Photon Source, ANL, ranged from 300 Å-10 µm. Using the Unified Fit model, level-1 analysis showed that the scatterers were 2D objects with either a smooth, a rough, or a diffuse surface. These 2D objects had an average radius of gyration Rg1 between 200-1500 Å. Level-2 analysis displayed a slope between -1 and -2. Use of the Guinier-Porod model gave s ≈ 1 thus showing that it was cylinders (TAGwoods) aggregating with fractal dimension 1 ≤ D2 ≤ 2. D2 = 1 is consistent with 1D structures formed from TAGwoods, while D2 = 2 implies that the TAGwoods had formed structures characteristic of diffusion or reaction limited cluster-cluster aggregation (DLCA/RLCA). These aggregates exhibited radii of gyration, Rg2, between 2500 and 6500 Å. Level-3 analyses showed diffuse surfaces, for most of the systems. These interpretations are in accord with theoretical models which studied crystalline nano-platelets (CNPs) coated with nano-scale layers arising from phase separation at the CNP surfaces. These layers could be due to either liquid-liquid phase separation with the CNPs coated, uniformly or non-uniformly, by a diffuse layer of TAGs, or solid-liquid phase separation with the CNPs coated by a rough layer of crystallites. A fundamental understanding of the self-organizing structures arising in these systems helps advance the characterization of fat crystal networks from nanometres to micrometres. This research can be used to design novel fat structures that use healthier fats via nano- and meso-scale structural engineering.

Graphene-coated polystyrene-divinylbenzene dispersive solid-phase extraction coupled with supercritical fluid chromatography for the rapid determination of 10 allergenic disperse dyes in industrial wastewater samples.

PubMed

Lou, Chaoyan; Wu, Can; Zhang, Kai; Guo, Dandan; Jiang, Lei; Lu, Yang; Zhu, Yan

2018-05-18

Allergenic disperse dyes are a group of environmental contaminants, which are toxic and mutagenic to human beings. In this work, a method of dispersive solid-phase extraction (d-SPE) using graphene-coated polystyrene-divinylbenzene (G@PS-DVB) microspheres coupled with supercritical fluid chromatography (SFC) was proposed for the rapid determination of 10 allergenic disperse dyes in industrial wastewater samples. G@PS-DVB microspheres were synthesized by coating graphene (G) sheets onto polystyrene-divinylbenzene (PS-DVB) polymers. Such novel sorbents were employed in d-SPE for the purification and concentration of allergenic disperse dyes in wastewater samples prior to the determination by SFC with UV detection. To achieve the maximum extraction efficiency for the target dyes, several parameters influencing d-SPE process such as sorbent dosage, extraction time, desorption conditions were investigated. SFC conditions including stationary phase, modifier composition and percentage, column temperature, backpressure and flow rate were optimized to well separate the allergenic disperse dyes. Under the optimum conditions, satisfactory linear relationship (R ≥ 0.9989) was observed with the concentration of dyes ranging from 0.02 to 10.0 μg/mL. The limits of detection (LOD, S/N = 3) for the ten dyes were in the range of 1.1-15.6 ng/mL. Recoveries for the spiked samples were between 89.1% and 99.7% with relative standard deviations (RSD) lower than 10.5% in all cases. The proposed method is time-saving, green, precise and repeatable for the analysis of the target dyes. Furthermore, the application of G@PS-DVB based d-SPE process can be potentially expanded to isolate and concentrate other aromatic compounds in various matrices and supercritical fluid chromatography methodology featuring rapidity, accuracy and green will be an ideal candidate for the analysis of these compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

Solid surface dependent layering of self-arranged structures with fibril-like assemblies of alpha-synuclein

NASA Astrophysics Data System (ADS)

Bukauskas, V.; Šetkus, A.; Šimkienė, I.; Tumėnas, S.; Kašalynas, I.; Rėza, A.; Babonas, J.; Časaitė, V.; Povilonienė, S.; Meškys, R.

2012-03-01

In present work the formation of hybrid constructions composed of alpha-synuclein-based colloidal solutions on various solid surfaces (silica coated Si, mica, CaF2 and KBr) is investigated by scanning probe microscopy, spectrocopic ellipsometry, Fourier transformed infrared spectroscopy and vibrational circular dichroism. Prior to the modification of the solids, the proteins were intentionally fibrilled under special conditions. It is proved that the multi-component coatings are self-arranged on the solid substrates. Depending on the substrate material, the interface films consisting of individual biomolecules can be detected on the solid surfaces. The coatings with fibril-like alpha-synuclein objects can be obtained on solid surfaces with negligible or comparatively thick interface films. The results are interpreted in terms of the charged surface-controlled electrostatic interaction between the substrate and the biomolecules. Solubility of solids is considered in this interpretation.

40 CFR 60.393 - Performance test and compliance provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... per volume of applied coating solids (G) during each calendar month for each affected facility by the following equation: EC16NO91.030 (E) For each EDP prime coat operation, calculate the turnover ratio (RT) by....392(a). (ii) If the volume weighted average mass of VOC per volume of applied coating solids (G...

Particle Engineering Via Mechanical Dry Coating in the Design of Pharmaceutical Solid Dosage Forms.

PubMed

Qu, Li; Morton, David A V; Zhou, Qi Tony

2015-01-01

Cohesive powders are problematic in the manufacturing of pharmaceutical solid dosage forms because they exhibit poor flowability, fluidization and aerosolization. These undesirable bulk properties of cohesive powders represent a fundamental challenge in the design of efficient pharmaceutical manufacturing processes. Recently, mechanical dry coating has attracted increasing attention as it can improve the bulk properties of cohesive powders in a cheaper, simpler, safer and more environment-friendly way than the existing solvent-based counterparts. In this review, mechanical dry coating techniques are outlined and their potential applications in formulation and manufacturing of pharmaceutical solid dosage forms are discussed. Reported data from the literature have shown that mechanical dry coating holds promise for the design of superior pharmaceutical solid formulations or manufacturing processes by engineering the interfaces of cohesive powders in an efficient and economical way.

Testing of Environmentally Preferable Aluminum Pretreatments and Coating Systems for Use on Space Shuttle Solid Rocket Boosters (SRB)

NASA Technical Reports Server (NTRS)

Clayton, C.; Raley, R.; Zook, L.

2001-01-01

The solid rocket booster (SRB) has historically used a chromate conversion coating prior to protective finish application. After conversion coating, an organic paint system consisting of a chromated epoxy primer and polyurethane topcoat is applied. An overall systems approach was selected to reduce waste generation from the coatings application and removal processes. While the most obvious waste reduction opportunity involved elimination of the chromate conversion coating, several other coating system configurations were explored in an attempt to reduce the total waste. This paper will briefly discuss the use of a systems view to reduce waste generation from the coating process and present the results of the qualification testing of nonchromated aluminum pretreatments and alternate coating systems configurations.

Tribological performance of Zinc soft metal coatings in solid lubrication

NASA Astrophysics Data System (ADS)

Regalla, Srinivasa Prakash; Krishnan Anirudh, V.; Reddy Narala, Suresh Kumar

2018-04-01

Solid lubrication by soft coatings is an important technique for superior tribological performance in machine contacts involving high pressures. Coating with soft materials ensures that the subsurface machine component wear decreases, ensuring longer life. Several soft metal coatings have been studied but zinc coatings have not been studied much. This paper essentially deals with the soft coating by zinc through electroplating on hard surfaces, which are subsequently tested in sliding experiments for tribological performance. The hardness and film thickness values have been found out, the coefficient of friction of the zinc coating has been tested using a pin on disc wear testing machine and the results of the same have been presented.

Environmentally Compatible Vapor-Phase Corrosion Inhibitor for Space Shuttle Hardware

NASA Technical Reports Server (NTRS)

Novak, Howard L.; Hall, Phillip B.; Martin, David (Technical Monitor)

2002-01-01

USA-SRB Element is responsible for the assembly and refurbishment of the non-motor components of the SRB as part of Space Shuttle. Thrust Vector Control (TVC) frames structurally support components of the TVC system located in the aft skirt of the SRB (Solid Rocket Booster). TVC frames are exposed to the seacoast environment after refurbishment and, also, to seawater immersion after splashdown, and during tow-back to CCAFS-Hangar AF refurbishment facilities. During refurbishment operations it was found that numerous TVC frames were experiencing internal corrosion and coating failures, both from salt air and seawater intrusions. Inspectors using borescopes would visually examine the internal cavities of the complicated aluminum alloy welded tubular structure. It was very difficult for inspectors to examine cavity corners and tubing intersections and particularly. to determine the extent of the corrosion and coating anomalies. Physical access to TVC frame internal cavities for corrosion removal and coating repair was virtually impossible, and an improved method using a Liquid (water based) Vapor-phase Corrosion Inhibitor (LVCI) for preventing initiation of new corrosion, and mitigating and/or stopping existing corrosion growth was recommended in lieu of hazardous paint solvents and high VOC/solvent based corrosion inhibitors. In addition, the borescopic inspection method used to detect corrosion, and/or coating anomalies had severe limitations because of part geometry, and an improved non-destructive inspection (NDI) method using Neutron Radiography (N-Ray) was also recommended.

Gas-Phase Synthesis of Gold- and Silica-Coated Nanoparticles

NASA Astrophysics Data System (ADS)

Boies, Adam Meyer

2011-12-01

Composite nanoparticles consisting of separate core-shell materials are of interest for a variety of biomedical and industrial applications. By combining different materials at the nanoscale, particles can exhibit enhanced or multi-functional behavior such as plasmon resonance combined with superparamagnetism. Gas-phase nanoparticle synthesis processes are promising because they can continuously produce particles with high mass-yield rates. In this dissertation, new methods are investigated for producing gas-phase coatings of nanoparticles in an "assembly-line" fashion. Separate processes are developed to create coatings from silica and gold that can be used with a variety of core-particle chemistries. A photoinduced chemical vapor deposition (photo-CVD) method is used to produce silica coatings from tetraethyl orthosilicate (TEOS) on the surface of nanoparticles (diameter ˜5--70 nm). Tandem differential mobility analysis (TDMA) of the process demonstrates that particle coatings can be produced with controllable thicknesses (˜1--10 nm) by varying system parameters such as precursor flow rate. Electron microscopy and infrared spectroscopy confirm that the photo-CVD films uniformly coat the particles and that the coatings are silica. In order to describe the coating process a chemical mechanism is proposed that includes gas-phase, surface and photochemical reactions. A chemical kinetics model of the mechanism indicates that photo-CVD coating proceeds primarily through the photodecomposition of TEOS which removes ethyl groups, thus creating activated TEOS species. The activated TEOS then adsorbs onto the surface of the particle where a series of subsequent reactions remove the remaining ethyl groups to produce a silica film with an open site for further attachment. The model results show good agreement with the experimentally measured coating trends, where increased TEOS flow increases coating thickness and increased nitrogen flow decreases coating thickness. Gold decoration of nanoparticles is accomplished by evaporation of solid gold in the presence of an aerosol flow. A hot-wire generation method is developed where gold particles are produced from a composite gold-platinum wire. Investigations of the hot-wire generator show that it can produce particles with a range of sizes and that more uniform, non-agglomerated particles are produced when using smaller diameter tubes where gas velocities across the wire are higher and recirculation zones are diminished. When gold is evaporated in the presence of silica nanoparticles, the silica aerosol is decorated by gold through either homogeneous gold nucleation and subsequent scavenging by the silica nanoparticles, or by heterogeneous nucleation on the silica surface in which the gold "balls up" due to the high surface tension of gold on silica. In both cases the resulting particles exhibit a plasmon absorbance resonance typical of gold nanoparticles (lambda˜550 nm). Finally, the silica coating and gold decoration processes are combined with a thermal plasma technique for synthesizing iron-oxide to produce tri-layer nanoparticles.

Polydopamine-coated magnetic nanoparticles for isolation and enrichment of estrogenic compounds from surface water samples followed by liquid chromatography-tandem mass spectrometry determination.

PubMed

Capriotti, Anna Laura; Cavaliere, Chiara; La Barbera, Giorgia; Piovesana, Susy; Samperi, Roberto; Zenezini Chiozzi, Riccardo; Laganà, Aldo

2016-06-01

Estrogens, phytoestrogens, and mycoestrogens may enter into the surface waters from different sources, such as effluents of municipal wastewater treatment plants, industrial plants, and animal farms and runoff from agricultural areas. In this work, a multiresidue analytical method for the determination of 17 natural estrogenic compounds, including four steroid estrogens, six mycoestrogens, and seven phytoestrogens, in river water samples has been developed. (Fe3O4)-based magnetic nanoparticles coated by polydopamine (Fe3O4@pDA) were used for dispersive solid-phase extraction, and the final extract was analyzed by ultra-high performance liquid chromatography coupled with tandem mass spectrometry. The Fe3O4 magnetic nanoparticles were prepared by a co-precipitation procedure, coated by pDA, and characterized by scanning electron microscopy, infrared spectroscopy, and elemental analysis. The sample preparation method was optimized in terms of extraction recovery, matrix effect, selectivity, trueness, precision, method limits of detection, and method limits of quantification (MLOQs). For all the 17 analytes, recoveries were >70 % and matrix effects were below 30 % when 25 mL of river water sample was treated with 90 mg of Fe3O4@pDA nanoparticles. Selectivity was tested by spiking river water samples with 50 other compounds (mycotoxins, antibacterials, conjugated hormones, UV filters, alkylphenols, etc.), and only aflatoxins and some benzophenones showed recoveries >60 %. This method proved to be simple and robust and allowed the determination of natural estrogenic compounds belonging to different classes in surface waters with MLOQs ranging between 0.003 and 0.1 μg L(-1). Graphical Abstract Determination of natural estrogenic compounds in water by magnetic solid phase extraction followed by liquid chromatography-tandem mass spectrometry analysis.

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.

Dispersive admicelle solid-phase extraction based on sodium dodecyl sulfate coated Fe3 O4 nanoparticles for the selective adsorption of three alkaloids in Gegen-Qinlian oral liquid before high-performance liquid chromatography.

PubMed

Shi, Zhihong; Xu, Dan; Zhao, Xuan; Li, Xinghong; Shen, Huimin; Yang, Bing; Zhang, Hongyi

2017-12-01

A novel dispersive admicelle solid-phase extraction method based on sodium dodecyl sulfate-coated Fe 3 O 4 nanoparticles was developed for the selective adsorption of berberine, coptisine, and palmatine in Gegen-Qinlian oral liquid before high-performance liquid chromatography. Fe 3 O 4 nanoparticles were synthesized by a chemical coprecipitation method and characterized by using transmission electron microscopy. Under acidic conditions, the surface of Fe 3 O 4 nanoparticles was coated with sodium dodecyl sulfate to form a nano-sized admicelle magnetic sorbent. Owing to electrostatic interaction, the alkaloids were adsorbed onto the oppositely charged admicelle magnetic nanoparticles. The quick separation of the analyte-adsorbed nanoparticles from the sample solution was performed by using Nd-Fe-B magnet. Best extraction efficiency was achieved under the following conditions: 800 μL Fe 3 O 4 nanoparticles suspension (20 mg/mL), 150 μL sodium dodecyl sulfate solution (10 mg/mL), pH 2, and vortexing time 2 min for the extraction of alkaloids from 10 mL of diluted sample. Four hundred microliters of methanol was used to desorb the alkaloids by vortexing for 1 min. Satisfactory extraction recoveries were obtained in the range of 85.9-120.3%, relative standard deviations for intra- and interday precisions were less than 6.3 and 10.0%, respectively. Finally, the established method was successfully applied to analyze the alkaloids in two batches of Gegen-Qinlian oral liquids. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrodeposition of self-assembled poly(3,4-ethylenedioxythiophene) @gold nanoparticles on stainless steel wires for the headspace solid-phase microextraction and gas chromatographic determination of several polycyclic aromatic hydrocarbons.

PubMed

Yang, Liu; Zhang, Jie; Zhao, Faqiong; Zeng, Baizhao

2016-11-04

In this work, a novel poly(3,4-ethylenedioxythiophene)@Au nanoparticles (PEDOT@AuNPs) hybrid coating was prepared and characterized. Firstly, the monomer 3,4-ethylenedioxythiophene was self-assembled on AuNPs, and then electropolymerization was performed on a stainless steel wire by cyclic voltammetry. The obtained PEDOT@AuNPs coating was rough and showed cauliflower-like micro-structure with thickness of ∼40μm. It displayed high thermal stability (up to 330°C) and mechanical stability and could be used for at least 160 times of solid phase microextraction (SPME) without decrease of extraction performance. The coating exhibited high extraction capacity for some environmental pollutants (e.g. naphthalene, 2-methylnaphthalene, acenaphthene, fluorene and phenathrene) due to the hydrophobic interaction between the analytes and PEDOT and the additional physicochemical affinity between polycyclic aromatic hydrocarbons and AuNPs. Through coupling with GC detection, good linearity (correlation coefficients higher than 0.9894), wide linear range (0.01-100μgL -1 ), low limits of detection (2.5-25ngL -1 ) were achieved for these analytes. The reproducibility (defined as RSD) was 1.1-4.0% and 5.8-9.9% for single fiber (n=5) and fiber-to-fiber (n=5), respectively. The SPME-GC method was successfully applied for the determination of three real samples, and the recoveries for standards added were 89.9-106% for lake water, 95.7-112% for rain water and 93.2-109% for soil saturated water, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Composite Solid Electrolyte For Lithium Cells

NASA Technical Reports Server (NTRS)

Peled, Emmanuel; Nagasubramanian, Ganesan; Halpert, Gerald; Attia, Alan I.

1994-01-01

Composite solid electrolyte material consists of very small particles, each coated with thin layer of Lil, bonded together with polymer electrolyte or other organic binder. Material offers significant advantages over other solid electrolytes in lithium cells and batteries. Features include high ionic conductivity and strength. Composite solid electrolyte expected to exhibit flexibility of polymeric electrolytes. Polymer in composite solid electrolyte serves two purposes: used as binder alone, conduction taking place only in AI2O3 particles coated with solid Lil; or used as both binder and polymeric electrolyte, providing ionic conductivity between solid particles that it binds together.

Stress-induced phase sensitivity of small diameter polarization maintaining solid-core photonic crystal fibre

NASA Astrophysics Data System (ADS)

Zhang, Zhihao; Zhang, Chunxi; Xu, Xiaobin

2017-09-01

Small diameter (cladding and coating diameter of 100 and 135 μm) polarization maintaining photonic crystal fibres (SDPM-PCFs) possess many unique properties and are extremely suitable for applications in fibre optic gyroscopes. In this study, we have investigated and measured the stress characteristics of an SDPM-PCF using the finite-element method and a Mach-Zehnder interferometer, respectively. Our results reveal a radial and axial sensitivity of 0.315 ppm/N/m and 25.2 ppm per 1 × 105 N/m2, respectively, for the SDPM-PCF. These values are 40% smaller than the corresponding parameters of conventional small diameter (cladding and coating diameter of 80 and 135 μm) panda fibres.

Effects of magnetic impurity scattering on superfluid 3He in aerogel

NASA Astrophysics Data System (ADS)

Aoyama, Kazushi; Ikeda, Ryusuke

2009-02-01

We investigate impurity effects on superfluid 3He in aerogel whose surface is not coated with 4He, different from most experimental situations. In systems with no 4He coating, spins of solid 3He absorbed on the aerogel surface are active and interact with spins of quasiparticles relevant to superfluidity and, for this reason, such an aerogel is treated as magnetic scatterers. It is found that, in the ABM pairing state affected by magnetic scatterings, not only the l-vector but also the d-vector has no long-ranged orientational order, and that the strong-coupling correction due to impurity scatterings is less suppressed than that in the nonmagnetic case, implying an expansion of the A-like phase region.

Semiconductor nanocrystals covalently bound to solid inorganic surfaces using self-assembled monolayers

DOEpatents

Alivisatos, A. Paul; Colvin, Vicki L.

1998-01-01

Methods are described for attaching semiconductor nanocrystals to solid inorganic surfaces, using self-assembled bifunctional organic monolayers as bridge compounds. Two different techniques are presented. One relies on the formation of self-assembled monolayers on these surfaces. When exposed to solutions of nanocrystals, these bridge compounds bind the crystals and anchor them to the surface. The second technique attaches nanocrystals already coated with bridge compounds to the surfaces. Analyses indicate the presence of quantum confined clusters on the surfaces at the nanolayer level. These materials allow electron spectroscopies to be completed on condensed phase clusters, and represent a first step towards synthesis of an organized assembly of clusters. These new products are also disclosed.

Strain-tolerant ceramic coated seal

DOEpatents

Schienle, James L.; Strangman, Thomas E.

1994-01-01

A metallic regenerator seal is provided having multi-layer coating comprising a NiCrAlY bond layer, a yttria stabilized zirconia (YSZ) intermediate layer, and a ceramic high temperature solid lubricant surface layer comprising zinc oxide, calcium fluoride, and tin oxide. An array of discontinuous grooves is laser machined into the outer surface of the solid lubricant surface layer making the coating strain tolerant.

Effects of high temperature treatment on microstructure and mechanical properties of laser-clad NiCrBSi/WC coatings on titanium alloy substrate

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

Li, Guang Jie; Li, Jun, E-mail: jacob_lijun@sina.com; Luo, Xing

2014-12-15

Laser-clad composite coatings on the Ti6Al4V substrate were heat-treated at 700, 800, and 900 °C for 1 h. The effects of post-heat treatment on the microstructure, microhardness, and fracture toughness of the coatings were investigated by scanning electron microscopy, X-ray diffractometry, energy dispersive spectroscopy, and optical microscopy. The wear resistance of the coatings was evaluated under dry reciprocating sliding friction at room temperature. The coatings mainly comprised some coarse gray blocky (W,Ti)C particles accompanied by the fine white WC particles, a large number of black TiC cellular/dendrites, and the matrix composed of NiTi and Ni{sub 3}Ti; some unknown rich Ni-more » and Ti-rich particles with sizes ranging from 10 nm to 50 nm were precipitated and uniformly distributed in the Ni{sub 3}Ti phase to form a thin granular layer after heat treatment at 700 °C. The granular layer spread from the edge toward the center of the Ni{sub 3}Ti phase with increasing temperature. A large number of fine equiaxed Cr{sub 23}C{sub 6} particles with 0.2–0.5 μm sizes were observed around the edges of the NiTi supersaturated solid solution when the temperature was further increased to 900 °C. The microhardness and fracture toughness of the coatings were improved with increased temperature due to the dispersion-strengthening effect of the precipitates. Dominant wear mechanisms for all the coatings included abrasive and delamination wear. The post-heat treatment not only reduced wear volume and friction coefficient, but also decreased cracking susceptibility during sliding friction. Comparatively speaking, the heat-treated coating at 900 °C presented the most excellent wear resistance. - Highlights: • TiC + WC reinforced intermetallic compound matrix composite coatings were produced. • The formation mechanism of the reinforcements was analyzed. • Two precipitates were generated at elevated temperature. • Cracking susceptibility and microhardness of the coatings were improved. • Post-heat treatment enhances wear resistance of the coatings.« less

MCrAlY bond coat with enhanced yttrium

DOEpatents

Jablonski, Paul D.; Hawk, Jeffrey A.

2016-08-30

One or more embodiments relates to a method of producing an MCrAlY bond coat comprising an MCrAlY layer in contact with a Y--Al.sub.2O.sub.3 layer. The MCrAlY layer is comprised of a .gamma.-M solid solution, a .beta.-MAl intermetallic phase, and Y-type intermetallics. The Y--Al.sub.2O.sub.3 layer is comprised of Yttrium atoms coordinated with oxygen atoms comprising the Al.sub.2O.sub.3 lattice. The method comprises depositing an MCrAlY material on a substrate, applying an Y.sub.2O.sub.3 paste, and heating the substrate in a non-oxidizing atmosphere at a temperature between 400-1300.degree. C. for a time sufficient to generate the Y--Al.sub.2O.sub.3 layer. Both the MCrAlY layer and the Y--Al.sub.2O.sub.3 layer have a substantial absence of Y.sub.2O.sub.3, YAG, and YAP phases.

Experimental research results of solid particle erosion resistance of blade steel with protective coating

NASA Astrophysics Data System (ADS)

Kachalin, G. V.; Mednikov, A. F.; Tkhabisimov, A. B.; Seleznev, L. I.

2017-11-01

The paper presents the results of metallographic studies and solid particle erosion tests of uncoated blade steel 20kH13 samples and samples with a protective coating based on chromium carbide (Cr-CrC) at a flow (air) velocity CA = 180 m/s, flow temperature tA = 25 °C, attack angle α = 30° and consumption of solid abrasive particles GP = 5·10-4 kg/s. It was found that the coating has a granular structure, a thickness is about 11 μm, the microhardness of the surface is 1520 ± 50 HV0.05. Processing of the obtained data by statistical analysis methods showed that the protective coating based on Cr-CrC increases the solid particle erosion resistance of the blade steel 20kH13 by the incubation-transitional period duration more than 2.5 times.

Magnetic Solid Phase Extraction Based on Oleic Acid Coated Fe3O4 for the Determination of Benzo[α]pyrene in Cigarette Smoke Coupled with High-Performance Liquid Chromatography.

PubMed

Feng, Shouai; Wei, Kang; Tian, Zhaofu; Li, Xiaolan; Meng, Dongling; Liao, Wenlong; Miao, Mingming; Yang, Yaling

2016-07-29

In this work, a simple and effective method based on magnetic solid-phase extraction combined with high-performance liquid chromatography was developed for the determination of benzo[α]pyrene (BaP) in cigarette smoke. Oleic acid coated Fe 3 O 4 (Fe 3 O 4 -OA) was synthesized and directly used as an efficient sorbent for the first time in magnetic solid-phase extraction (MSPE) procedure for the clean-up of BaP in cigarette smoke extracts. The synthesized Fe 3 O 4 -OA was characterized by transmission electron microscopy, X-ray diffraction and Fourier transformed infrared spectroscopy. The extraction via Fe 3 O 4 -OA was dispersed in the extracts of cigarette smoke followed by the magnetic isolation, acetonitrile-tetrahydrofuran (ACN-THF; v/v = 9:1) was used for desorption of the analyte. The effects of important parameters such as the amount of adsorbent, solution pH, the content of acetonitrile, temperature and sorption time were investigated. The method showed good linearity for the determination of BaP in the concentration range of 0.5-50 ng mL -1 with a regression coefficient (R 2 ) of 0.9987. The limit of detection and limit of quantification for BaP were obtained to be 0.12 and 0.41 ng mL -1 , respectively. The mean recoveries were in the range from 81.0% to 97.6% at low, medium, high spiked levels, and the relative standard deviations were in the range of 2.7-6.8%. Combined with high-performance liquid chromatography and fluorescence detection, a simple and effective method was developed for the analysis of BaP in cigarette smoke. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Insights on beer volatile profile: Optimization of solid-phase microextraction procedure taking advantage of the comprehensive two-dimensional gas chromatography structured separation.

PubMed

Martins, Cátia; Brandão, Tiago; Almeida, Adelaide; Rocha, Sílvia M

2015-06-01

The aroma profile of beer is crucial for its quality and consumer acceptance, which is modu-lated by a network of variables. The main goal of this study was to optimize solid-phase microextraction experimental parameters (fiber coating, extraction temperature, and time), taking advantage of the comprehensive two-dimensional gas chromatography structured separation. As far as we know, it is the first time that this approach was used to the untargeted and comprehensive study of the beer volatile profile. Decarbonation is a critical sample preparation step, and two conditions were tested: static and under ultrasonic treatment, and the static condition was selected. Considering the conditions that promoted the highest extraction efficiency, the following parameters were selected: poly(dimethylsiloxane)/divinylbenzene fiber coating, at 40ºC, using 10 min of pre-equilibrium followed by 30 min of extraction. Around 700-800 compounds per sample were detected, corresponding to the beer volatile profile. An exploratory application was performed with commercial beers, using a set of 32 compounds with reported impact on beer aroma, in which different patterns can be observed through the structured chromatogram. In summary, the obtained results emphasize the potential of this methodology to allow an in-depth study of volatile molecular composition of beer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetic solid phase extraction using ionic liquid-coated core-shell magnetic nanoparticles followed by high-performance liquid chromatography for determination of Rhodamine B in food samples.

PubMed

Chen, Jieping; Zhu, Xiashi

2016-06-01

Three hydrophobic ionic liquids (ILs) (1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6), 1-hexyl-3-methyl-imidazole hexafluoro-phosphate ([HMIM]PF6), and 1-octyl-3-methylimidazole hexafluorophosphate ([OMIM]PF6)) were used to coat Fe3O4@SiO2 nanoparticles (NPs) with core-shell structures to prepare magnetic solid phase extraction (MSPE) agents (Fe3O4@SiO2@IL). A novel method of MSPE coupled with high-performance liquid chromatography for the separation/analysis of Rhodamine B was then established. The results showed that Rhodamine B was adsorbed rapidly on Fe3O4@SiO2@[OMIM]PF6 and was released using ethanol. Under optimal conditions, the pre-concentration factor for the proposed method was 25. The linear range, limit of detection (LOD), correlation coefficient (R), and relative standard deviation (RSD) were found to be 0.50-150.00 μgL(-1), 0.08 μgL(-1), 0.9999, and 0.51% (n=3, c=10.00 μgL(-1)), respectively. The Fe3O4@SiO2 NPs could be re-used up to 10 times. The method was successfully applied to the determination of Rhodamine B in food samples. Copyright © 2016. Published by Elsevier Ltd.

Optimization of a sensitive method for the determination of nitro musk fragrances in waters by solid-phase microextraction and gas chromatography with micro electron capture detection using factorial experimental design.

PubMed

Polo, Maria; Garcia-Jares, Carmen; Llompart, Maria; Cela, Rafael

2007-08-01

A solid-phase microextraction method (SPME) followed by gas chromatography with micro electron capture detection for determining trace levels of nitro musk fragrances in residual waters was optimized. Four nitro musks, musk xylene, musk moskene, musk tibetene and musk ketone, were selected for the optimization of the method. Factors affecting the extraction process were studied using a multivariate approach. Two extraction modes (direct SPME and headspace SPME) were tried at different extraction temperatures using two fiber coatings [Carboxen-polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane-divinylbenzene (PDMS/DVB)] selected among five commercial tested fibers. Sample agitation and the salting-out effect were also factors studied. The main effects and interactions between the factors were studied for all the target compounds. An extraction temperature of 100 degrees C and sampling the headspace over the sample, using either CAR/PDMS or PDMS/DVB as fiber coatings, were found to be the experimental conditions that led to a more effective extraction. High sensitivity, with detection limits in the low nanogram per liter range, and good linearity and repeatability were achieved for all nitro musks. Since the method proposed performed well for real samples, it was applied to different water samples, including wastewater and sewage, in which some of the target compounds (musk xylene and musk ketone) were detected and quantified.

Barley husk carbon as the fiber coating for the solid-phase microextraction of twelve pesticides in vegetables prior to gas chromatography-mass spectrometric detection.

PubMed

Liang, Weiqian; Wang, Juntao; Zang, Xiaohuan; Dong, Wenhuan; Wang, Chun; Wang, Zhi

2017-03-31

In this work, a barley husk biomaterial was successfully carbonized by hydrothermal method. The carbon had a high specific surface area and good stability. It was coated onto a stainless steel wire through sol-gel technique to prepare a solid-phase microextraction fiber for the extraction of trace levels of twelve pesticides (tsumacide, fenobucarb, indoxacarb, diethofencarb, thimet, terbufos, malathion, thiamethoxam, imidacloprid, buprofezin, acetamiprid, thiamethoxam) from vegetable samples prior to gas chromatography-mass spectrometric (GC-MS) detection. The main experimental parameters that could influence the extraction efficiency such as extraction time, extraction temperature, sample pH, sample salinity, stirring rate, desorption temperature and desorption time, were investigated. Under the optimized conditions, the linearity was observed in the range of 0.2-75.0μgkg -1 for tomato samples, and 0.3-60.0μgkg -1 for cucumber samples, with the correlation coefficients (r) ranging from 0.9959 to 0.9983. The limits of detection of the method were 0.01-0.05μgkg -1 for tomato samples, and 0.03-0.10μgkg -1 for cucumber samples. The recoveries of the analytes for the method from spiked samples were in the range of 76%-104%, and the precision, expressed as the relative standard deviations, was less than 12%. Copyright © 2017 Elsevier B.V. All rights reserved.

Mixed hemimicelles solid-phase extraction based on sodium dodecyl sulfate (SDS)-coated nano-magnets for the spectrophotometric determination of Fingolomid in biological fluids

NASA Astrophysics Data System (ADS)

Azari, Zhila; Pourbasheer, Eslam; Beheshti, Abolghasem

2016-01-01

In this study, mixed hemimicelles solid-phase extraction (SPE) based on sodium dodecyl sulfate (SDS)-coated nano-magnets Fe3O4 was investigated as a novel method for the separation and determination of Fingolimod (FLM) in water, urine and plasma samples prior to spectrophotometeric determination. Due to the high surface area of these new sorbents and the excellent adsorption capacity after surface modification by SDS, satisfactory extraction recoveries can be produced. The main factors affecting the adsolubilization of analysts, such as pH, surfactant and adsorbent amounts, ionic strength, extraction time and desorption conditions were studied and optimized. Under the selected conditions, FLM has been quantitatively extracted. The accuracy of the method was evaluated by recovery measurements on spiked samples, and good recoveries of 96%, 95% and 88% were observed for water, urine and plasma respectively. Proper linear behaviors over the investigated concentration ranges of 2-26, 2-17 and 2-13 mg/L with good coefficients of determination, 0.998, 0.997 and 0.995 were achieved for water, urine and plasma samples, respectively. To the best of our knowledge, this is the first time that a mixed hemimicelles SPE method based on magnetic separation and nanoparticles has been used as a simple and sensitive method for monitoring of FLM in water and biological samples.

CO2 sorption on surface-modified carbonaceous support: Probing the influence of the carbon black microporosity and surface polarity

NASA Astrophysics Data System (ADS)

Gargiulo, Valentina; Alfè, Michela; Ammendola, Paola; Raganati, Federica; Chirone, Riccardo

2016-01-01

The use of solid sorbents is a convenient option in post-combustion CO2 capture strategies. Sorbents selection is a key point because the materials are required to be both low-cost and versatile in typical post-combustion conditions in order to guarantee an economically advantageous overall process. This work compares strategies to tailor the chemico-physical features of carbon black (CB) by surface-modification and/or coating with a CO2-sorbent phase. The influence of the CB microporosity, enhanced by chemical/thermal treatments, is also taken into account. Three CB surface modifications are performed and compared: (i) oxidation and functionalization with amino-groups, (ii) coating with iron oxides and (iii) impregnation with an ionic liquid (IL). The CO2 capture performance is evaluated on the basis of the breakthrough curves measured at atmospheric pressure and room temperature in a lab-scale fixed bed micro-reactor. Most of tested solids adsorb a CO2 amount significantly higher than a 13X zeolite and DARCO FGD (Norit) activated carbon (up to 4 times more in the best case). The sorbents bearing basic functionalities (amino-groups and IL) exhibit the highest CO2 sorption capacity. The use of a microporous carbonaceous support limits the accessibility of CO2 toward the adsorbing phase (IL or FM) lowering the number of accessible binding sites for CO2.

Doping of three-dimensional porous carbon nanotube-graphene-ionic liquid composite into polyaniline for the headspace solid-phase microextraction and gas chromatography determination of alcohols.

PubMed

Li, Lulu; Wu, Mian; Feng, Yingying; Zhao, Faqiong; Zeng, Baizhao

2016-12-15

In this work, ionic liquid (IL, i.e. 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate), carboxyl multiwall carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO) were used to prepare three-dimensional porous material (MWCNTs-rGO-IL) by one-step self-assembly, then it was co-electrodeposited with polyaniline (PANI) on stainless steel wires by cyclic voltammetry. The resulting coating (PANI-MWCNTs-rGO-IL) was characterized by using FT-IR and scanning electron microscopy etc, and it showed porous structure and had high thermal stability. Furthermore, it was found to be very suitable for the headspace solid-phase microextraction of alcohols (i.e. octanol, nonanol, geraniol, decanol, undecanol and dodecanol). By coupling with gas chromatography, wide linear ranges and low limits of detection (i.e. 2.2-28.3 ng L -1 ) were obtained for the alcohols. The coating also presented good repeatability and reproducibility; the relative standard deviations for intra-fiber and fiber-to-fiber were less than 5.6% (n = 5) and 7.0% (n = 5) respectively. In addition, the proposed method was successfully applied to the determination of alcohols in tea drinks, and the recoveries for standards added were 85.6-114%. Copyright © 2016 Elsevier B.V. All rights reserved.

In Situ Synthesis of Porous Carbons by Using Room-Temperature, Atmospheric-Pressure Dielectric Barrier Discharge Plasma as High-Performance Adsorbents for Solid-Phase Microextraction.

PubMed

Lin, Yao; Wu, Li; Xu, Kailai; Tian, Yunfei; Hou, Xiandeng; Zheng, Chengbin

2015-09-21

A one-step, template-free method is described to synthesize porous carbons (PCs) in situ on a metal surface by using a room-temperature, atmospheric-pressure dielectric barrier discharge (DBD) plasma. This method not only features high efficiency, environmentally friendliness, and low cost and simple equipment, but also can conveniently realize large-area synthesis of PCs by only changing the design of the DBD reactor. The synthesized PCs have a regulated nestlike morphology, and thus, provide a high specific surface area and high pore volume, which result in excellent adsorption properties. Its applicability was demonstrated by using a PC-coated stainless-steel fiber as a solid-phase microextraction (SPME) fiber to preconcentrate polycyclic aromatic hydrocarbons (PAHs) prior to analysis by gas chromatography with flame ionization detection (GC-FID). The results showed that the fiber exhibited excellent enrichment factors (4.1×10(4) to 3.1×10(5)) toward all tested PAHs. Thus, the PC-based SPME-GC-FID provides low limits of detection (2 to 20 ng L(-1)), good precision (<7.8%), and good recoveries (80-115%) for ultra-sensitive determination of PAHs in real water samples. In addition, the PC-coated fiber could be stable enough for more than 500 replicate extraction cycles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchical Graphene coating for highly sensitive solid phase microextraction of organochlorine pesticides.

PubMed

Wang, Fuxin; Liu, Shuqin; Yang, Hao; Zheng, Juan; Qiu, Junlang; Xu, Jianqiao; Tong, Yexiang; Zhu, Fang; Ouyang, Gangfeng

2016-11-01

Graphene, a novel class of carbon nanostructures, has received great attention as sorbents due to its fascinating structures, ultrahigh specific surface area, and good extraction ability. In this paper, a new type of hierarchical graphene was synthesized through employing a mild and environment-friendly method. Such 3D interconnected graphene own a high specific surface area up to 524m(2)g(-1), which is about 2.5 fold larger than the graphene, since the synthetic material has interlayer pores between nanosheets and in-plane pores. Then a superior solid-phase microextraction fiber was fabricated by sequentially coating the stainless steel fiber with silicone sealant film and hierarchical graphene powder. Since the novel hierarchical graphene possessed large surface area and good adsorption property, the as-prepared fiber exhibited good extraction properties of the organochlorine pesticides (OCPs). As for the analytical performance, the as-prepared fiber achieved low detection limits (0.08-0.80ngL(-1)) and wide linearity (10-30,000ngL(-1)) under the optimal conditions. The repeatability (n=5) for single fiber were between 5.1% and 11%, while the reproducibility (n=3) of fiber-to-fiber were range from 6.2% to14%. Moreover, the fiber was successfully applied to the analysis of OCPs in the Pearl River water. Copyright © 2016 Elsevier B.V. All rights reserved.

Dispersive solid-phase extraction based on oleic acid-coated magnetic nanoparticles followed by gas chromatography-mass spectrometry for UV-filter determination in water samples.

PubMed

Román, Iván P; Chisvert, Alberto; Canals, Antonio

2011-05-06

A sensitive analytical method to concentrate and determine extensively used UV filters in cosmetic products at (ultra)trace levels in water samples is presented. The method is based on a sample treatment using dispersive solid-phase extraction (dSPE) with laboratory-made chemisorbed oleic acid-coated cobalt ferrite (CoFe(2)O(4)@oleic acid) magnetic nanoparticles (MNPs) as optimized sorbent for the target analytes. The variables involved in dSPE were studied and optimized in terms of sensitivity, and the optimum conditions were: mass of sorbent, 100mg; donor phase volume, 75 mL; pH, 3; and sodium chloride concentration, 30% (w/v). After dSPE, the MNPs were eluted twice with 1.5 mL of hexane, and then the eluates were evaporated to dryness and reconstituted with 50 μL of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) for the injection into the gas chromatography-mass spectrometry (GC-MS). Under the optimized experimental conditions the method provided good levels of repeatability with relative standard deviations below 16% (n=5, at 100 ng L(-1) level). Limit of detection values ranged between 0.2 and 6.0 ng L(-1), due to the high enrichment factors achieved (i.e., 453-748). Finally, the proposed method was applied to the analysis of water samples of different origin (tap, river and sea). Recovery values showed that the matrices under consideration do not significantly affect the extraction process. Copyright © 2011 Elsevier B.V. All rights reserved.

Immobilized humic substances and immobilized aggregates of humic substances as sorbent for solid phase extraction.

PubMed

Erny, Guillaume L; Gonçalves, Bruna M; Esteves, Valdemar I

2013-09-06

In this work, humic substances (HS) immobilized, as a thin layer or as aggregates, on silica gel were tested as material for solid phase extraction. Some triazines (simazine, atrazine, therbutylazine, atrazine-desethyl-desisopropyl-2-hydroxy, ametryn and terbutryn), have been selected as test analytes due to their environmental importance and to span a large range of solubility and octanol/water partition coefficient (logP). The sorbent was obtained immobilizing a thin layer of HS via physisorption on a pre-coated silica gel with a cationic polymer (polybrene). While the sorbent could be used as it is, it was demonstrated that additional HS could be immobilized, via weak interactions, to form stable humic aggregates. However, while a higher quantity of HS could be immobilized, no significant differences were observed in the sorption parameters. This sorbent have been tested for solid phase extraction to concentrate triazines from aqueous matrixes. The sorbent demonstrated performances equivalent to commercial alternatives as a concentration factor between 50 and 200, depending on the type of triazines, was obtained. Moreover the low cost and the high flow rate of sample through the column allowed using high quantity of sorbent. The analytical procedure was tested with different matrixes including tap water, river water and estuarine water. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous Determination of Parathion, Malathion, Diazinon, and Pirimiphos Methyl in Dried Medicinal Plants Using Solid-Phase Microextraction Fibre Coated with Single-Walled Carbon Nanotubes

PubMed Central

Ahmadkhaniha, Reza; Samadi, Nasrin; Salimi, Mona; Sarkhail, Parisa; Rastkari, Noushin

2012-01-01

A reliable and sensitive headspace solid-phase microextraction gas chromatography-mass spectrometry method for simultaneous determination of different organophosphorus pesticides in dried medicinal plant samples is described. The analytes were extracted by single-walled carbon nanotubes as a new solid-phase microextraction adsorbent. The developed method showed good performance. For diazinon and pirimiphos methyl calibration, curves were linear (r 2 ≥ 0.993) over the concentration ranges from 1.5 to 300 ng g−1, and the limit of detection at signal-to-noise ratio of 3 was 0.3 ng g−1. For parathion and malathion, the linear range and limit of detection were 2.5–300 (r 2 ≥ 0.991) and 0.5 ng g−1, respectively. In addition, a comparative study between the single-walled carbon nanotubes and a commercial polydimethylsiloxane fibre for the determination of target analytes was carried out. Single-walled carbon nanotubes fibre showed higher extraction capacity, better thermal stability (over 350°C), and longer lifespan (over 250 times) than the commercial polydimethylsiloxane fibre. The developed method was successfully applied to determine target organophosphorus pesticides in real samples. PMID:22645439

A novel poly(3,4-ethylenedioxythiophene)-ionic liquid composite coating for the headspace solid-phase microextraction and gas chromatography determination of several alcohols in soft drinks.

PubMed

Wu, Mian; Zhang, Haibo; Zhao, Faqiong; Zeng, Baizhao

2014-11-19

A novel poly(3,4-ethylenedioxythiophene)-ionic liquid (i.e., 1-hydroxyethyl-3-methyl imidazolium-bis[(trifluoromethyl)sulfonyl]imide) composite film was electrodeposited on a Pt wire for headspace solid-phase microextraction. The film showed nodular structure and had large specific surface. In addition, it displayed high thermal stability (up to 300°C) and durable property (could be used for more than 200 times). Coupled with gas chromatography-flame ionization detection, the resulting fiber was applied to the headspace solid-phase microextraction and determination of several alcohols (i.e., linalool, nonanol, terpineol, geraniol, decanol and dodecanol). It presented higher extraction capability in comparison with the poly(3,4-ethylenedioxythiophene) and commercial polydimethylsiloxane/divinylbenzene fiber. Under the optimized conditions, the linear ranges exceeded three magnitudes with correlation coefficients above 0.9952 and the low limits of detection were 34.2-81.3ng L(-1). For different alcohols the repeatabilities (defined as RSD) were <5.8% and <7.8% for single fiber (n=5) and fiber-to-fiber (n=4), respectively. The proposed method was applied to the determination of these alcohols in real samples with acceptable recoveries from 81.1% to 106.6%. Copyright © 2014 Elsevier B.V. All rights reserved.

Nanowire membrane-based nanothermite: towards processable and tunable interfacial diffusion for solid state reactions.

PubMed

Yang, Yong; Wang, Peng-peng; Zhang, Zhi-cheng; Liu, Hui-ling; Zhang, Jingchao; Zhuang, Jing; Wang, Xun

2013-01-01

Interfacial diffusion is of great importance in determining the performance of solid-state reactions. For nanometer sized particles, some solid-state reactions can be triggered accidently by mechanical stress owing to their large surface-to-volume ratio compared with the bulk ones. Therefore, a great challenge is the control of interfacial diffusion for solid state reactions, especially for energetic materials. Here we demonstrate, through the example of nanowire-based thermite membrane, that the thermite solid-state reaction can be easily tuned via the introduction of low-surface-energy coating layer. Moreover, this silicon-coated thermite membrane exhibit controlled wetting behavior ranging from superhydrophilic to superhydrophobic and, simultaneously, to significantly reduce the friction sensitivity of thermite membrane. This effect enables to increase interfacial resistance by increasing the amount of coating material. Indeed, our results described here make it possible to tune the solid-state reactions through the manipulation of interfacial diffusion between the reactants.

Nanowire Membrane-based Nanothermite: towards Processable and Tunable Interfacial Diffusion for Solid State Reactions

NASA Astrophysics Data System (ADS)

Yang, Yong; Wang, Peng-Peng; Zhang, Zhi-Cheng; Liu, Hui-Ling; Zhang, Jingchao; Zhuang, Jing; Wang, Xun

2013-04-01

Interfacial diffusion is of great importance in determining the performance of solid-state reactions. For nanometer sized particles, some solid-state reactions can be triggered accidently by mechanical stress owing to their large surface-to-volume ratio compared with the bulk ones. Therefore, a great challenge is the control of interfacial diffusion for solid state reactions, especially for energetic materials. Here we demonstrate, through the example of nanowire-based thermite membrane, that the thermite solid-state reaction can be easily tuned via the introduction of low-surface-energy coating layer. Moreover, this silicon-coated thermite membrane exhibit controlled wetting behavior ranging from superhydrophilic to superhydrophobic and, simultaneously, to significantly reduce the friction sensitivity of thermite membrane. This effect enables to increase interfacial resistance by increasing the amount of coating material. Indeed, our results described here make it possible to tune the solid-state reactions through the manipulation of interfacial diffusion between the reactants.

Wear and corrosion resistance of laser-cladded Fe-based composite coatings on AISI 4130 steel

NASA Astrophysics Data System (ADS)

Fan, Li; Chen, Hai-yan; Dong, Yao-hua; Dong, Li-hua; Yin, Yan-sheng

2018-06-01

The wear and corrosion resistance of Fe72.2Cr16.8Ni7.3Mo1.6Mn0.7C0.2Si1.2 and Fe77.3Cr15.8Ni3.9Mo1.1Mn0.5C0.2Si1.2 coatings laser-cladded on AISI 4130 steel were studied. The coatings possess excellent wear and corrosion resistance despite the absence of expensive yttrium, tungsten, and cobalt and very little molybdenum. The microstructure mainly consists of dendrites and eutectic phases, such as duplex (γ+α)-Fe and the Fe-Cr (Ni) solid solution, confirmed via energy dispersive spectrometry and X-ray diffraction. The cladded Fe-based coatings have lower coefficients of friction, and narrower and shallower wear tracks than the substrate without the cladding, and the main wear mechanism is mild abrasive wear. Electrochemical test results suggest that the soft Fe72.2Cr16.8Ni7.3Mo1.6Mn0.7C0.2Si1.2 coating with high Cr and Ni concentrations has high passivation resistance, low corrosion current, and positive corrosion potential, providing a better protective barrier layer to the AISI 4130 steel against corrosion.

Porous, High Capacity Coatings for Solid Phase Microextraction by Sputtering.

PubMed

Diwan, Anubhav; Singh, Bhupinder; Roychowdhury, Tuhin; Yan, DanDan; Tedone, Laura; Nesterenko, Pavel N; Paull, Brett; Sevy, Eric T; Shellie, Robert A; Kaykhaii, Massoud; Linford, Matthew R

2016-02-02

We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H2SO4 and 30% H2O2) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3-9, 3-5, 2.5-4.5, and 1.5-2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane-hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0-1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested, and the between-fiber reproducibility (n = 3) was 0-15%, generally 5-10%, for all analytes tested. The repeatabilities of our sputtered fibers and the commercial 7 μm PDMS fiber are essentially the same. Fibers could be used for at least 300 extractions without loss of performance. More than 50 compounds were identified in a gas chromatography-mass spectrometry headspace analysis of a real world botanical sample with the 2.0 μm fiber.

Solid Liquid Interdiffusion Bonding of Zn4Sb3 Thermoelectric Material with Cu Electrode

NASA Astrophysics Data System (ADS)

Lin, Y. C.; Lee, K. T.; Hwang, J. D.; Chu, H. S.; Hsu, C. C.; Chen, S. C.; Chuang, T. H.

2016-10-01

The ZnSb intermetallic compound may have thermoelectric applications because it is low in cost and environmentally friendly. In this study, a Zn4Sb3 thermoelectric element coated with a Ni barrier layer and a Ag reaction layer was bonded with a Ag-coated Cu electrode using a Ag/Sn/Ag solid-liquid interdiffusion bonding process. The results indicated that a Ni5Zn21 intermetallic phase formed easily at the Zn4Sb3/Ni interface, leading to sound adhesion. In addition, Sn film was found to react completely with the Ag layer to form a Ag3Sn intermetallic layer having a melting point of 480°C. The resulting Zn4Sb3 thermoelectric module can be applied at the optimized operation temperature (400°C) of Zn4Sb3 material as a thermoelectric element. The bonding strengths ranged from 14.9 MPa to 25.0 MPa, and shear tests revealed that the Zn4Sb3/Cu-joints fractured through the interior of the thermoelectric elements.

Measurements of the Diameter and Velocity Distributions of Atomized Tablet-Coating Solutions for Pharmaceutical Applications

NASA Astrophysics Data System (ADS)

Osterday, Kathryn; Aliseda, Alberto; Lasheras, Juan

2009-11-01

The atomization of colloidal suspensions is of particular interest to the manufacturing of tablets and pills used as drug delivery systems by the pharmaceutical industry. At various stages in the manufacturing process, the tablets are coated with a spray of droplets produced by co-axial atomizers. The mechanisms of droplet size and spray formation in these types of atomizers are dominated by Kelvin-Helmholtz and Raleigh-Taylor instabilities for both low[1] and high[2] Ohnesorge numbers. We present detailed phase Doppler measurements of the Sauter Mean Diameter of the droplets produced by co-axial spray atomizers using water-based colloidal suspensions with solid concentrations ranging from fifteen to twenty percent and acetone-based colloidal suspensions with solid concentrations ranging from five to ten percent. Our results compare favorably with predictions by Aliseda's model. This suggests that the final size distribution is mainly determined by the instabilities caused by the sudden acceleration of the liquid interface. [1]Varga, C. M., et al. (2003) J. Fluid Mech. 497:405-434 [2]Aliseda, A. et al. (2008). J. Int. J. Multiphase Flow, 34(2), 161-175.

Solid Particle Erosion Behaviors of Carbon-Fiber Epoxy Composite and Pure Titanium

NASA Astrophysics Data System (ADS)

Cai, Feng; Gao, Feng; Pant, Shashank; Huang, Xiao; Yang, Qi

2016-01-01

Rotor blades of Bell CH-146 Griffon helicopter experience excessive solid particle erosion at low altitudes in desert environment. The rotor blade is made of an advanced light-weight composite which, however, has a low resistance to solid particle erosion. Coatings have been developed and applied to protect the composite blade. However, due to the influence of coating process on composite material, the compatibility between coating and composite base, and the challenges of repairing damaged coatings as well as the inconsistency between the old and new coatings, replaceable thin metal shielding is an alternative approach; and titanium, due to its high-specific strength and better formability, is an ideal candidate. This work investigates solid particle erosion behaviors of carbon-fiber epoxy composite and titanium in order to assess the feasibility of titanium as a viable candidate for erosion shielding. Experiment results showed that carbon-fiber epoxy composite showed a brittle erosion behavior, whereas titanium showed a ductile erosion mode. The erosion rate on composite was 1.5 times of that on titanium at impingement angle 15° and increased to 5 times at impact angle 90°.

Microporous Ti implant compact coated with hydroxyapatite produced by electro-discharge-sintering and electrostatic-spray-deposition.

PubMed

Jo, Y J; Kim, Y H; Jo, Y H; Seong, J G; Chang, S Y; Van Tyne, C J; Lee, W H

2014-11-01

A single pulse of 1.5 kJ/0.7 g of atomized spherical Ti powder from 300 μF capacitor was applied to produce the porous-surfaced Ti implant compact by electro-discharge-sintering (EDS). A solid core surrounded by porous layer was self-consolidated by a discharge in the middle of the compact in 122 μsec. Average pore size, porosity, and compressive yield strength of EDS Ti compact were estimated to be about 68.2 μm, 25.5%, and 266.4 MPa, respectively. Coatings with hydroxyapatite (HAp) on the Ti compact were conducted by electrostatic-spray-deposition (ESD) method. As-deposited HAp coating was in the form of porous structure and consisted of HAp particles which were uniformly distributed on the Ti porous structure. By heat-treatment at 700 degrees C, HAp particles were agglomerated each other and melted to form a highly smooth and homogeneous HAp thin film consisted of equiaxed nano-scaled grains. Porous-surfaced Ti implant compacts coated with highly crystalline apatite phase were successfully obtained by using the EDS and ESD techniques.

Development and optimization of a solid-phase microextraction gas chromatography-tandem mass spectrometry methodology to analyse ultraviolet filters in beach sand.

PubMed

Vila, Marlene; Llompart, Maria; Garcia-Jares, Carmen; Homem, Vera; Dagnac, Thierry

2018-06-06

A methodology based on solid-phase microextraction (SPME) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for the simultaneous analysis of eleven multiclass ultraviolet (UV) filters in beach sand. To the best of our knowledge, this is the first time that this extraction technique is applied to the analysis of UV filters in sand samples, and in other kind of environmental solid samples. Main extraction parameters such as the fibre coating, the amount of sample, the addition of salt, the volume of water added to the sand, and the temperature were optimized. An experimental design approach was implemented in order to find out the most favourable conditions. The final conditions consisted of adding 1 mL of water to 1 g of sample followed by the headspace SPME for 20 min at 100 °C, using PDMS/DVB as fibre coating. The SPME-GC-MS/MS method was validated in terms of linearity, accuracy, limits of detection and quantification, and precision. Recovery studies were also performed at three concentration levels in real Atlantic and Mediterranean sand samples. The recoveries were generally above 85% and relative standard deviations below 11%. The limits of detection were in the pg g -1 level. The validated methodology was successfully applied to the analysis of real sand samples collected from Atlantic Ocean beaches in the Northwest coast of Spain and Portugal, Canary Islands (Spain), and from Mediterranean Sea beaches in Mallorca Island (Spain). The most frequently found UV filters were ethylhexyl salicylate (EHS), homosalate (HMS), 4-methylbenzylidene camphor (4MBC), 2-ethylhexyl methoxycinnamate (2EHMC) and octocrylene (OCR), with concentrations up to 670 ng g -1 . Copyright © 2018 Elsevier B.V. All rights reserved.

The adhesion solidity, physico-mechanical and tribological properties of the coating of titanium nitride

NASA Astrophysics Data System (ADS)

Krivina, L. A.; Tarasenko, Yu P.; Fel, Ya A.

2017-05-01

Influence of variable technological factors (arch current, fractional pressure of gas in the camera) on structure, physic-mechanical and tribological features of an ion-plasma coating of titanium nitride has been investigated. The adhesion solidity has been put to the test and the mechanism of destruction of a covering has been also researched by a skretch-test method. The optimal mode of spraying at which the formation of the nanostructured bar coating of TiN has been defined. The covering offers an optimal combination of physic-mechanical, tribological and solidity features.

Effect of fabrication parameters on coating properties of tubular solid oxide fuel cell electrolyte prepared by vacuum slurry coating

NASA Astrophysics Data System (ADS)

Son, Hui-Jeong; Song, Rak-Hyun; Lim, Tak-Hyoung; Lee, Seung-Bok; Kim, Sung-Hyun; Shin, Dong-Ryul

The process of vacuum slurry coating for the fabrication of a dense and thin electrolyte film on a porous anode tube is investigated for application in solid oxide fuel cells. 8 mol% yttria stabilized zirconia is coated on an anode tube by vacuum slurry-coating process as a function of pre-sintering temperature of the anode tube, vacuum pressure, slurry concentration, number of coats, and immersion time. A dense electrolyte layer is formed on the anode tube after final sintering at 1400 °C. With decrease in the pre-sintering temperature of the anode tube, the grain size of the coated electrolyte layer increases and the number of surface pores in the coating layer decreases. This is attributed to a reduced difference in the respective shrinkage of the anode tube and the electrolyte layer. The thickness of the coated electrolyte layer increases with the content of solid powder in the slurry, the number of dip-coats, and the immersion time. Although vacuum pressure has no great influence on the electrolyte thickness, higher vacuum produces a denser coating layer, as confirmed by low gas permeability and a reduced number of defects in the coating layer. A single cell with the vacuum slurry coated electrolyte shows a good performance of 620 mW cm -2 (0.7 V) at 750 °C. These experimental results indicate that the vacuum slurry-coating process is an effective method to fabricate a dense thin film on a porous anode support.

Nucleic acid hybridization with RNA immobilized on filter paper.

NASA Technical Reports Server (NTRS)

Saxinger, W. C.; Ponnamperuma, C.; Gillespie, D.

1972-01-01

RNA has been immobilized in a manner suitable for use in molecular hybridization experiments with dissolved RNA or DNA by a nonaqueous solid-phase reaction with carbonyldiimidazole and RNA 'dry coated' on cellulose or, preferably, on previously activated phosphocellulose filters. Immobilization of RNA does not appear to alter its chemical character or cause it to acquire affinity for unspecific RNA or DNA. The versatility and efficiency of this method make it potentially attractive for use in routine analytical or preparative hybridization experiments, among other applications.

On the Bonding Strength of Fe-Based Self-Fluxing Alloy Coating Deposited by Different Methods on the Steel Substrate

NASA Astrophysics Data System (ADS)

Feldshtein, E.; Kardapolava, M.; Dyachenko, O.

2018-05-01

In the present paper, the bonding strength of Fe-based self-fluxing alloy coating deposited by plasma spraying, gluing and laser remelting and alloying on the steel substrate have been investigated. When flame melting, a globular structure is formed. Against the background of the solid solution carbide-boride phases are clearly distinguishable, between which the Fe-Fe2B and Fe-FeB eutectic colonies are situated. Laser remelting leads to the formation of metastable structures, reinforced with dendrites, consisting of alloyed Fe-α and Fe-γ. At the low laser beam speeds the coating is melted completely with the formation of a cast structure with the dendrites. When the laser beam speed is increased, the dendritic structure gets fragmented. Structures of coatings alloyed with B4C and remelted by the laser beam vary with the increase of the spot speed. The bonding strength of coating without subsequent remelting decreases by 4-5 times in comparison with remelted. The bonding strength of the reinforced glue coating has adhesive and adhesive-cohesive character. When the load increases in the coating, microcracks develop, which gradually spread to the center of the bonding surface. For plasma coatings after laser remelting without additional alloying, the maximum bonding strength is observed with the minimum laser beam speed. With increasing the laser beam speed it decreases almost 1.5 times. In glue coatings reinforced with B4C particulates by laser remelting, the bonding strength is lower by 1.2-1.4 times in comparison with plasma coating.

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

Sherman, Andrew J

A heterogeneous body having ceramic rich cermet regions in a more ductile metal matrix. The heterogeneous bodies are formed by thermal spray operations on metal substrates. The thermal spray operations apply heat to a cermet powder and project it onto a solid substrate. The cermet powder is composed of complex composite particles in which a complex ceramic-metallic core particle is coated with a matrix precursor. The cermet regions are generally comprised of complex ceramic-metallic composites that correspond approximately to the core particles. The cermet regions are approximately lenticular shaped with an average width that is at least approximately twice themore » average thickness. The cermet regions are imbedded within the matrix phase and generally isolated from one another. They have obverse and reverse surfaces. The matrix phase is formed from the matrix precursor coating on the core particles. The amount of heat applied during the formation of the heterogeneous body is controlled so that the core particles soften but do not become so fluid that they disperse throughout the matrix phase. The force of the impact on the surface of the substrate tends to flatten them. The flattened cermet regions tend to be approximately aligned with one another in the body.« less

The properties and behavior of α-pinene secondary organic aerosol particles exposed to ammonia under dry conditions

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

Bell, David M.; Imre, Dan; T. Martin, Scot

Chemical transformations and aging of secondary organic aerosol (SOA) particles can alter their physical and chemical properties, including particle morphology. Ammonia, one of the common atmospheric reactive constituents, can react with SOA particles, changing their properties and behavior. At low relative humidity NH3 uptake by α-pinene SOA particles appears to be limited to the particle surface, which suggests that the reacted particles might not be homogeneous and have complex morphology. Here, we present a study aimed at detailed characterization of the effect of ammonia on the composition, density, morphology, shape, and evaporation kinetics of α-pinene SOA particles. We find thatmore » a small amount of NH3 diffuses and reacts throughout the particles bulk, while most of the ammoniated products result from the reaction of NH3 with carboxylic acids on the particle surface, leading to a slight increase in particle size. We show that the reaction products form a solid semi-volatile coating that is a few nanometers thick. This solid coating prevents coagulating particles from coalescing for over two days. However, when the gas phase is diluted this semi-volatile coating evaporates in minutes, which is ensued by rapid coalescence. The ammoniated products in the particle bulk affect particles evaporation kinetics, more so for the smaller particles that contain higher fraction of ammoniated products.« less

The effect of heat treatment on structural and electronic properties of niobium nitride prepared by a thermal diffusion method

DOE PAGES

Farha, Ashraf Hassan; Ozkendir, Osman Murat; Elsayed-Ali, Hani E.; ...

2016-11-15

NbN coatings are prepared onto Nb substrate by thermal diffusion at high temperatures. The formation of NbN coating by thermal diffusion was studied in the range of 1250-1500 °C at constant nitrogen background gas pressure (1.3x10 -3 Pa) and processing time (180 min). The electronic and crystal structures of the NbN coatings were investigated. It was found that nitrogen diffuses into Nb forming the Nb-N solid solution (bcc) a-NbN phase that starts to appear above 1250 °C. Increasing the processing temperature gives richer a-phase concentration. Besides, X-ray absorption spectroscopy (XAS) was performed to study the electronic structure of the NbNmore » layer. The results of the electronic structural study corroborate the crystal structural analysis. The Nb M 3,2 edge X-ray absorption spectroscopy (XAS) spectrum shows strong temperature dependence. At the highest processing temperature (1500 °C), the number of d holes increased. Nitrogen diffusion into Nb is resulting to increase electrostatic interaction between d electron and core hole. Lastly, for the studied conditions, only the α-NbN was observed in the X-ray diffraction patterns.« less

The effect of heat treatment on structural and electronic properties of niobium nitride prepared by a thermal diffusion method

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

Farha, Ashraf Hassan; Ozkendir, Osman Murat; Elsayed-Ali, Hani E.

NbN coatings are prepared onto Nb substrate by thermal diffusion at high temperatures. The formation of NbN coating by thermal diffusion was studied in the range of 1250-1500 °C at constant nitrogen background gas pressure (1.3x10 -3 Pa) and processing time (180 min). The electronic and crystal structures of the NbN coatings were investigated. It was found that nitrogen diffuses into Nb forming the Nb-N solid solution (bcc) a-NbN phase that starts to appear above 1250 °C. Increasing the processing temperature gives richer a-phase concentration. Besides, X-ray absorption spectroscopy (XAS) was performed to study the electronic structure of the NbNmore » layer. The results of the electronic structural study corroborate the crystal structural analysis. The Nb M 3,2 edge X-ray absorption spectroscopy (XAS) spectrum shows strong temperature dependence. At the highest processing temperature (1500 °C), the number of d holes increased. Nitrogen diffusion into Nb is resulting to increase electrostatic interaction between d electron and core hole. Lastly, for the studied conditions, only the α-NbN was observed in the X-ray diffraction patterns.« less

A comparison study on a sulfonated graphene-polyaniline nanocomposite coated fiber for analysis of nicotine in solid samples through the traditional and vacuum-assisted HS-SPME.

PubMed

Ghiasvand, Alireza; Koonani, Samira; Yazdankhah, Fatemeh; Farhadi, Saeid

2018-02-05

A simple, rapid, and reliable headspace solid-phase microextraction (HS-SPME) procedure, reinforced by applying vacuum in the extraction vial, was developed. It was applied for the extraction of nicotine in solid samples prior to determination by gas chromatography-flame ionization detection (GC-FID). First, the surface of a narrow stainless steel wire was made porous and adhesive by platinization to obtain a durable, higher surface area, and resistant fiber. Then, a thin film of sulfonated graphene/polyaniline (Sulf-G/PANI) nanocomposite was synthesized and simultaneously coated on the platinized fiber using the electrophoretic deposition (EPD) method. It was demonstrated that the extraction efficiency remarkably increased by applying the reduced-pressure condition in the extraction vial. To evaluate the conventional HS-SPME and vacuum-assisted HS-SPME (VA-HS-SPME) platforms, all experimental parameters affecting the extraction efficiency including desorption time and temperature, extraction time and temperature and moisture content of sample matrix were optimized. The highest extraction efficiency was obtained at 60°C, 10min (extraction temperature and time) and 280°C, 2min (desorption condition), for VA-HS-SPME strategy, while for conventional HS-SPME the extraction and desorption conditions found to be 100°C, 30min and 280°C, 2min, respectively. The Sulf-G/PANI coated fiber showed high thermal stability, good chemical/mechanical resistance, and long lifetime. For analysis of nicotine in solid samples using VA-HS-SPME-GC-FID, linear dynamic range (LDR) was 0.01-30μgg -1 (R 2 =0.996), the relative standard deviation (RSD%, n=6), for analyses of 1μgg -1 nicotine was calculated 3.4% and limit of detection (LOD) found to be 0.002μgg -1 . The VA-HS-SPME-GC-FID strategy was successfully carried out for quantitation of nicotine in hair and tobacco real samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Slip-mediated dewetting of polymer microdroplets

PubMed Central

McGraw, Joshua D.; Chan, Tak Shing; Maurer, Simon; Salez, Thomas; Benzaquen, Michael; Raphaël, Elie; Brinkmann, Martin; Jacobs, Karin

2016-01-01

Classical hydrodynamic models predict that infinite work is required to move a three-phase contact line, defined here as the line where a liquid/vapor interface intersects a solid surface. Assuming a slip boundary condition, in which the liquid slides against the solid, such an unphysical prediction is avoided. In this article, we present the results of experiments in which a contact line moves and where slip is a dominating and controllable factor. Spherical cap-shaped polystyrene microdroplets, with nonequilibrium contact angle, are placed on solid self-assembled monolayer coatings from which they dewet. The relaxation is monitored using in situ atomic force microscopy. We find that slip has a strong influence on the droplet evolutions, both on the transient nonspherical shapes and contact line dynamics. The observations are in agreement with scaling analysis and boundary element numerical integration of the governing Stokes equations, including a Navier slip boundary condition. PMID:26787903

Semiconductor nanocrystals covalently bound to solid inorganic surfaces using self-assembled monolayers

DOEpatents

Alivisatos, A.P.; Colvin, V.L.

1998-05-12

Methods are described for attaching semiconductor nanocrystals to solid inorganic surfaces, using self-assembled bifunctional organic monolayers as bridge compounds. Two different techniques are presented. One relies on the formation of self-assembled monolayers on these surfaces. When exposed to solutions of nanocrystals, these bridge compounds bind the crystals and anchor them to the surface. The second technique attaches nanocrystals already coated with bridge compounds to the surfaces. Analyses indicate the presence of quantum confined clusters on the surfaces at the nanolayer level. These materials allow electron spectroscopies to be completed on condensed phase clusters, and represent a first step towards synthesis of an organized assembly of clusters. These new products are also disclosed. 10 figs.

Method for sealing remote leaks in an enclosure using an aerosol

DOEpatents

Modera, Mark P.; Carrie, Francois R.

1999-01-01

The invention is a method and device for sealing leaks remotely by means of injecting a previously prepared aerosol into the enclosure being sealed according to a particular sealing efficiency defined by the product of a penetration efficiency and a particle deposition efficiency. By using different limits in the relationship between penetration efficiency and flowrate, the same method according the invention can be used for coating the inside of an enclosure. Specifically the invention is a method and device for preparing, transporting, and depositing a solid phase aerosol to the interior surface of the enclosure relating particle size, particle carrier flow rate, and pressure differential, so that particles deposited there can bridge and substantially seal each leak, with out providing a substantial coating at inside surfaces of the enclosure other than the leak. The particle size and flow parameters can be adjusted to coat the interior of the enclosure (duct) without substantial plugging of the leaks depending on how the particle size and flowrate relationships are chosen.

Nanowire Membrane-based Nanothermite: towards Processable and Tunable Interfacial Diffusion for Solid State Reactions

PubMed Central

Yang, Yong; Wang, Peng-peng; Zhang, Zhi-cheng; Liu, Hui-ling; Zhang, Jingchao; Zhuang, Jing; Wang, Xun

2013-01-01

Interfacial diffusion is of great importance in determining the performance of solid-state reactions. For nanometer sized particles, some solid-state reactions can be triggered accidently by mechanical stress owing to their large surface-to-volume ratio compared with the bulk ones. Therefore, a great challenge is the control of interfacial diffusion for solid state reactions, especially for energetic materials. Here we demonstrate, through the example of nanowire-based thermite membrane, that the thermite solid-state reaction can be easily tuned via the introduction of low-surface-energy coating layer. Moreover, this silicon-coated thermite membrane exhibit controlled wetting behavior ranging from superhydrophilic to superhydrophobic and, simultaneously, to significantly reduce the friction sensitivity of thermite membrane. This effect enables to increase interfacial resistance by increasing the amount of coating material. Indeed, our results described here make it possible to tune the solid-state reactions through the manipulation of interfacial diffusion between the reactants. PMID:23603809

Galvanizing and Galvannealing Behavior of CMnSiCr Dual-Phase Steels

NASA Astrophysics Data System (ADS)

Lin, Ko-Chun; Chu, Peng-Wei; Lin, Chao-Sung; Chen, Hon-Bor

2013-06-01

Alloying elements, such as Mn, Mo, Si, and Cr, are commonly used to enhance the strength of advanced high-strength steels. Those elements also play an important role in the hot-dip galvanizing (GI) and galvannealing (GA) process. In this study, two kinds of CMnSiCr dual-phase steels were galvanized and galvannealed using a hot-dip simulator to investigate the effect of the alloying elements on the microstructure of the GI and GA coatings. The results showed that the dual-phase steels had good galvanizability because no bare spots were observed and the Fe-Zn phases were readily formed at the interface. However, the alloying reaction during the GA process was significantly hindered. XPS analysis showed that external oxidation occurred under an extremely low dew point [213 K to 203 K (-60 °C to -70 °C)] atmosphere during the annealing prior to hot dipping. However, most of the oxides were reduced during the GI process. After the GI process, the Al was present as solid solutes in the Fe-Zn phase, suggesting that the Fe-Zn phase was formed from the transformation of the Fe-Al inhibition alloy. Meanwhile, the solubility of Si in the ζ phase was extremely low. With continued GA reaction, the ζ phase transformed into the δ phase, which contained approximately 1.0 at.pct Si. The Si also diffused into the Zn layer during the GA reaction. Hence, the ζ phase did not homogeneously nucleate at the steel substrate/Zn coating interface, but was found at the area away from the interface. Therefore, the Fe-Zn phases on the CMnSiCr dual-phase steels were relatively non-uniform compared to those on interstitial-free steel.

Analysis of coating structures and interfaces in solid oral dosage forms by three dimensional terahertz pulsed imaging.

PubMed

Zeitler, J Axel; Shen, Yaochun; Baker, Colin; Taday, Philip F; Pepper, Michael; Rades, Thomas

2007-02-01

Three dimensional terahertz pulsed imaging (TPI) was evaluated as a novel tool for the nondestructive characterization of different solid oral dosage forms. The time-domain reflection signal of coherent pulsed light in the far infrared was used to investigate film-coated tablets, sugar-coated tablets, multilayered controlled release tablets, and soft gelatin capsules. It is possible to determine the spatial and statistical distribution of coating thickness in single and multiple coated products using 3D TPI. The measurements are nondestructive even for layers buried underneath other coating structures. The internal structure of coating materials can be analyzed. As the terahertz signal penetrates up to 3 mm into the dosage form interfaces between layers in multilayered tablets can be investigated. In soft gelatin capsules it is possible to measure the thickness of the gelatin layer and to characterize the seal between the gelatin layers for quality control. TPI is a unique approach for the nondestructive characterization and quality control of solid dosage forms. The measurements are fast and fully automated with the potential for much wider application of the technique in the process analytical technology scheme. Copyright (c) 2006 Wiley-Liss, Inc.

CoxFe1-x oxide coatings on metallic interconnects for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Shen, Fengyu; Lu, Kathy

2016-10-01

In order to improve the performance of Cr-containing steel as an interconnect material for solid oxide fuel cells, CoFe alloy coatings with Co:Fe ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 are deposited by electrodeposition and then oxidized to CoxFe1-x oxide coatings with a thickness of ∼6 μm as protective layers on the interconnect. The area specific resistance of the coated interconnect increases with the Fe content. Higher Co content oxide coatings are more effective in limiting the growth of the chromia scale while all coatings are effective in inhibiting Cr diffusion and evaporation. With the Co0.8Fe0.2 oxide coated interconnect, the electrochemical performance of the Sm0.5Sr0.5Co0.2Fe0.8O3 cathode is improved. Only 1.54 atomic percentage of Cr is detected on the surface of the Sm0.5Sr0.5Co0.2Fe0.8O3 cathode while no Cr is detected 0.66 μm or more into the cathode. CoxFe1-x oxide coatings are promising candidates for solid oxide fuel cell interconnects with the advantage of using existing cathode species for compatibility and performance enhancement.

Modeling of gun barrel surface erosion: Historic perspective

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

Buckingham, A.C.

1996-08-01

Results and interpretations of numerical simulations of some dominant processes influencing gun barrel propellant combustion and flow-induced erosion are presented. Results include modeled influences of erosion reduction techniques such as solid additives, vapor phase chemical modifications, and alteration of surface solid composition through use of thin coatings. Precedents and historical perspective are provided with predictions from traditional interior ballistics compared to computer simulations. Accelerating reactive combustion flow, multiphase and multicomponent transport, flow-to-surface thermal/momentum/phase change/gas-surface chemical exchanges, surface and micro-depth subsurface heating/stress/composition evolution and their roles in inducing surface cracking, spall, ablation, melting, and vaporization are considered. Recognition is given tomore » cyclic effects of previous firing history on material preconditioning. Current perspective and outlook for future are based on results of a US Army-LLNL erosion research program covering 7 y in late 1970s. This is supplemented by more recent research on hypervelocity electromagnetic projectile launchers.« less

[Developments in preparation and experimental method of solid phase microextraction fibers].

PubMed

Yi, Xu; Fu, Yujie

2004-09-01

Solid phase microextraction (SPME) is a simple and effective adsorption and desorption technique, which concentrates volatile or nonvolatile compounds from liquid samples or headspace of samples. SPME is compatible with analyte separation and detection by gas chromatography, high performance liquid chromatography, and other instrumental methods. It can provide many advantages, such as wide linear scale, low solvent and sample consumption, short analytical times, low detection limits, simple apparatus, and so on. The theory of SPME is introduced, which includes equilibrium theory and non-equilibrium theory. The novel development of fiber preparation methods and relative experimental techniques are discussed. In addition to commercial fiber preparation, different newly developed fabrication techniques, such as sol-gel, electronic deposition, carbon-base adsorption, high-temperature epoxy immobilization, are presented. Effects of extraction modes, selection of fiber coating, optimization of operating conditions, method sensitivity and precision, and systematical automation, are taken into considerations in the analytical process of SPME. A simple perspective of SPME is proposed at last.

Evaluation of a headspace solid-phase microextraction method for the analysis of ignitable liquids in fire debris.

PubMed

Fettig, Ina; Krüger, Simone; Deubel, Jan H; Werrel, Martin; Raspe, Tina; Piechotta, Christian

2014-05-01

The chemical analysis of fire debris represents a crucial part in fire investigations to determine the cause of a fire. A headspace solid-phase microextraction (HS-SPME) procedure for the detection of ignitable liquids in fire debris using a fiber coated with a mixture of three different sorbent materials (Divinylbenzene/Carboxen/Polydimethylsiloxane, DVB/CAR/PDMS) is described. Gasoline and diesel fuel were spiked upon a preburnt matrix (wood charcoal), extracted and concentrated with HS-SPME and then analyzed with gas chromatography/mass spectrometry (GC/MS). The experimental conditions--extraction temperature, incubation and exposure time--were optimized. To assess the applicability of the method, fire debris samples were prepared in the smoke density chamber (SDC) and a controlled-atmosphere cone calorimeter. The developed methods were successfully applied to burnt particleboard and carpet samples. The results demonstrate that the procedure that has been developed here is suitable for detecting these ignitable liquids in highly burnt debris. © 2013 American Academy of Forensic Sciences.

Adjusted active carbon fibers for solid phase microextraction.

PubMed

Jia, Jinping; Feng, Xue; Fang, Nenghu; Wang, Yalin; Chen, Hongjin; Dan, Wu

2002-01-01

Adjusted active carbon fiber (AACF) was evaluated for Solid Phase Microextraction (SPME), which showed higher sensitivity and stability than traditional coating fibers. The characteristics of AACF result from two different activation methods (chemical and water vapor) and from variable activation conditions (temperature and time). The fiber treated by water vapor appears to have stronger affinity to polar compounds, while that treated by chemical activation appears to have stronger affinity to non-polar compounds. For different target compounds ranged from non-polar to polar, AACF design could be effective with specific selections and sensitivities. As applications in this paper, benzoic acid in soy sauce was extracted onto water-vapor-activated-fiber, then analyzed using gas chromatograph-mass spectrometer (GC-MS). The chemical-activated-fiber SPME was applied in the analysis of benzene series compounds (BTEX) in water matrix. Compared with standard carbon disulfide extraction method, chemical-activated-fiber SPME is more convenient due to its simple process and turns to be of relative low detection limits.

Automated solid-phase subcloning based on beads brought into proximity by magnetic force.

PubMed

Hudson, Elton P; Nikoshkov, Andrej; Uhlen, Mathias; Rockberg, Johan

2012-01-01

In the fields of proteomics, metabolic engineering and synthetic biology there is a need for high-throughput and reliable cloning methods to facilitate construction of expression vectors and genetic pathways. Here, we describe a new approach for solid-phase cloning in which both the vector and the gene are immobilized to separate paramagnetic beads and brought into proximity by magnetic force. Ligation events were directly evaluated using fluorescent-based microscopy and flow cytometry. The highest ligation efficiencies were obtained when gene- and vector-coated beads were brought into close contact by application of a magnet during the ligation step. An automated procedure was developed using a laboratory workstation to transfer genes into various expression vectors and more than 95% correct clones were obtained in a number of various applications. The method presented here is suitable for efficient subcloning in an automated manner to rapidly generate a large number of gene constructs in various vectors intended for high throughput applications.

Surface-modified multifunctional MIP nanoparticles

PubMed Central

Moczko, Ewa; Poma, Alessandro; Guerreiro, Antonio; de Vargas Sansalvador, Isabel Perez; Caygill, Sarah; Canfarotta, Francesco; Whitcombe, Michael J.; Piletsky, Sergey

2015-01-01

The synthesis of core-shell molecularly imprinted polymer nanoparticles (MIP NPs) has been performed using a novel solid-phase approach on immobilised templates. The same solid phase also acts as protective functionality for high affinity binding sites during subsequent derivatisation/shell formation. This procedure allows for the rapid synthesis, controlled separation and purification of high-affinity materials, with each production cycle taking just 2 hours. The aim of this approach is to synthesise uniformly-sized imprinted materials at the nanoscale which can be readily grafted with various polymers without affecting their affinity and specificity. For demonstration purposes we grafted anti-melamine MIP NPs with coatings which introduce the following surface characteristics: high polarity (PEG methacrylate); electro-activity (vinyl ferrocene); fluorescence (eosin acrylate); thiol groups (pentaerythritol tetrakis(3-mercaptopropionate)). The method has broad applicability and can be used to produce multifunctional imprinted nanoparticles with potential for further application in the biosensors, diagnostics and biomedical fields and as an alternative to natural receptors. PMID:23503559

Solvent-modified solid-phase microextraction for the determination of diazepam in human plasma samples by capillary gas chromatography.

PubMed

Krogh, M; Grefslie, H; Rasmussen, K E

1997-02-21

This paper describes microextraction and gas chromatographic analysis of diazepam from human plasma. The method was based on immobilisation of 1.5 microliters of 1-octanol on a polyacrylate-coated fiber designed for solid-phase microextraction. The solvent-modified fibre was used to extract diazepam from the samples. The plasma sample was pre-treated to release diazepam from the protein binding. The fibre was inserted into the modified plasma sample, adjusted to pH 5.5 an internal standard was added and the mixture was carefully stirred for 4 min. The fibre with the immobilised solvent and the enriched analytes was injected into the capillary gas chromatograph. The solvent and the extracted analytes were evaporated at 300 degrees C in the split-splitless injection port of the gas chromatograph, separated on a methylsilicon capillary column and detected with a nitrogen-phosphorus detector. The method was shown to be reproducible with a detection limit of 0.10 nmol/ml in human plasma.

Automated Solid-Phase Subcloning Based on Beads Brought into Proximity by Magnetic Force

PubMed Central

Hudson, Elton P.; Nikoshkov, Andrej; Uhlen, Mathias; Rockberg, Johan

2012-01-01

In the fields of proteomics, metabolic engineering and synthetic biology there is a need for high-throughput and reliable cloning methods to facilitate construction of expression vectors and genetic pathways. Here, we describe a new approach for solid-phase cloning in which both the vector and the gene are immobilized to separate paramagnetic beads and brought into proximity by magnetic force. Ligation events were directly evaluated using fluorescent-based microscopy and flow cytometry. The highest ligation efficiencies were obtained when gene- and vector-coated beads were brought into close contact by application of a magnet during the ligation step. An automated procedure was developed using a laboratory workstation to transfer genes into various expression vectors and more than 95% correct clones were obtained in a number of various applications. The method presented here is suitable for efficient subcloning in an automated manner to rapidly generate a large number of gene constructs in various vectors intended for high throughput applications. PMID:22624028

The Effect of Composition on the Surface Finish of PS400: A New High Temperature Solid Lubricant Coating

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Stanford, malcolm K.; Thomas, Fransua; Edmonds, Brian J.

2010-01-01

A new composite, multi-constituent, solid lubricant coating, NASA PS400, developed for high temperature tribological applications, exhibits a smoother surface finish after grinding and polishing than its predecessors PS200 and PS300. In this paper, the baseline composition of PS400 is modified to investigate each individual constituent s role on the achievable surface finish through a series of coating deposition, grinding, and polishing experiments. Furthermore, to explore the limits of compositional tailoring for improved tribological performance, several PS400 coatings were doped with additional solid lubricants (graphite, MoS2 and BN) and tribologically tested. The test results clearly showed that, compared to PS300 coatings, PS400 achieves a smoother surface finish via a reduced lubricant content. Coatings prepared with higher than the baseline level (10 wt%) of lubricants exhibited higher final surface roughness than the earlier generation PS300 coatings. Reducing or eliminating the one or both lubricants (fluorides or silver) did not further improve the surface finish suggesting that the current composition of PS400 is near optimal with respect to surface finish. Lastly, attempts to improve the poor initial room temperature tribological behavior of PS400 via the addition of traditional solid lubricants were unsuccessful. Based upon this work and earlier results it is expected that future research will concentrate on developing methods to produce a lubricious glaze on the rubbing surface during break in to ensure that low friction and wear are rapidly achieved.

Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

NASA Astrophysics Data System (ADS)

Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

2007-01-01

The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 1013 to 1015 n/cm2. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 1015 to 1016 n/cm2 with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

NASA Technical Reports Server (NTRS)

Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

2007-01-01

The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 10(exp 13) to 10(exp 15) n per square centimeters. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 10(exp 15) to 10(exp 16) n per square centimeters with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

Metastable Phase Evolution in Oxide Systems

NASA Astrophysics Data System (ADS)

Levi, Carlos G.

2005-03-01

Multi-component ceramics are often synthesized by routes that facilitate mixing at the molecular scale and subsequently generate a solid product at low homologous temperatures. Examples include chemical and physical vapor deposition, thermal spray, and pyrolytic decomposition of precursor solutions. In these processes the solid evolves rapidly from a highly energized state, typically in a temperature regime wherein long-range diffusion is largely constrained and the equilibrium configuration can be kinetically suppressed. The resulting product may exhibit various forms of metastability such as amorphization, nanocrystallinity, extended solid solubility and alternate crystalline forms. The approach allows access to novel combinations of structure and composition with unprecedented defect structures that, if reasonably durable, could have properties of potential technological interest. Understanding phase selection and evolution is facilitated by having a suitable reference framework depicting the thermodynamic hierarchy of the phases available to the system under the relevant processing conditions. When transformations are partitionless the phase menu and hierarchy can be readily derived from the relative position of the T0 curves/surfaces for the different pairs of phases. The result is a phase hierarchy map, which is an analog of the phase diagram for partitionless equilibrium. Such maps can then be used to assess the kinetic effects on the selection of metastable states and their subsequent evolution. This presentation will discuss the evolution of metastable phases in oxides, with emphasis on systems involving fluorite phases and their ordered or distorted derivatives. The concepts will be illustrated primarily with zirconia-based systems, notably those of interest in thermal barrier coatings, fuel cells and ferroelectrics (ZrO2-MO3/2, where M = Y, Sc, the lanthanides and combinations thereof, as well as ZrO2-YO3/2-TiO2, ZrO2-TiO2-PbO, etc.). Of particular interest are the durabilities of metastable phases in systems that operate at high temperature, their decomposition paths and the implications to their functionality.

Smectic order induced at homeotropically aligned nematic surfaces: A neutron reflection study

NASA Astrophysics Data System (ADS)

Lau, Y. G. J.; Richardson, Robert M.; Cubitt, R.

2006-06-01

Neutron reflection was used to measure the buildup of layers at a solid surface as the smectic phase is approached from higher temperatures in a nematic liquid crystal. The liquid crystal was 4-octyl-4'-cyanobiphenyl (8CB), and the solid was silicon with one of five different surface treatments that induce homeotropic alignment: (i) silicon oxide; (ii) a cetyltrimethylammonium bromide coating; (iii) an octadecyltrichlorosilane monolayer; (iv) an n-n-dimethyl-n-octadecyl-3- aminopropyltrimethyloxysilyl chloride monolayer; and (v) a lecithin coating. The development of surface smectic layers in the nematic phase of 8CB was followed by measuring specular reflectivity and monitoring the pseudo-Bragg peak from the layers. The scattering data were processed to remove the scattering from short-ranged smecticlike fluctuations in the bulk nematic phase from the specular reflection. The pseudo-Bragg peak at scattering vector Q ˜0.2Å-1 therefore corresponded to the formation of long-range smectic layers at the surface. The amplitude of the smectic density wave decayed with increasing distance from the surface, and the characteristic thickness of this smectic region diverged as the transition temperature was approached. It was found that the characteristic thickness for some of the surface treatments was greater than the correlation length in the bulk nematic. The different surfaces gave different values of the smectic order parameter at the surface. This suggests that the interaction with the surface is significantly different from a "hard wall" which would give the same values of the smectic order parameter and penetration depths similar to the bulk correlation length. Comparison of the different surfaces also suggested that the strength and range of the surface smectic ordering may be varied independently.

Formation of Microcracks During Micro-Arc Oxidation in a Phytic Acid-Containing Solution on Two-Phase AZ91HP

NASA Astrophysics Data System (ADS)

Zhang, R. F.; Chang, W. H.; Jiang, L. F.; Qu, B.; Zhang, S. F.; Qiao, L. P.; Xiang, J. H.

2016-04-01

Micro-arc oxidation (MAO) is an effective method to produce ceramic coatings on magnesium alloys and can considerably improve their corrosion resistance. The coating properties are closely related with microcracks, which are always inevitably developed on the coating surface. In order to find out the formation and development regularity of microcracks, anodic coatings developed on two-phase AZ91HP after different anodizing times were fabricated in a solution containing environmentally friendly organic electrolyte phytic acid. The results show that anodic film is initially developed on the α phase. At 50 s, anodic coatings begin to develop on the β phase, evidencing the formation of a rough area. Due to the coating successive development, the microcracks initially appear at the boundary between the initially formed coating on the α phase and the subsequently developed coating on the β phase. With the prolonging treatment time, the microcracks near the β phase become evident. After treating for 3 min, the originally rough area on the β phase disappears and the coatings become almost uniform with microcracks randomly distributed on the sample surface. Inorganic phosphates are found in MAO coatings, suggesting that phytate salts are decomposed due to the high instantaneous temperature on the sample surface resulted from spark discharge.

Investigation of Thermal Processing on the Properties of PS304: A Solid Lubricant Coating

NASA Technical Reports Server (NTRS)

Benoy, Patricia A.; Williams, Syreeta (Technical Monitor)

2002-01-01

The effect of thermal processing on PS304, a solid lubricant coating, was investigated. PS304 is a plasma sprayed solid lubricant consisting of 10% Ag and 10% BaF2 and CaF2 in a eutectic mixture for low and high temperature lubricity respectively. In addition, PS304 contains 20% Cr2O3 for increased hardness and 60% NiCr which acts as a binder. All percents are in terms of weight not volume. Previous research on thermal processing (NAG3-2245) of PS304 revealed that substrate affected both the pre- and post-anneal hardness of the plasma spray coating. The objective of this grant was to both quantify this effect and determine whether the root cause was an artifact of the substrate or an actual difference in hardness due to interaction between the substrate and the coating. In addition to clarifying past research developments new data was sought in terms of coating growth due to annealing.

Non-sticky translocation of bio-molecules through Tween 20-coated solid-state nanopores in a wide pH range

NASA Astrophysics Data System (ADS)

Li, Xiaoqing; Hu, Rui; Li, Ji; Tong, Xin; Diao, J. J.; Yu, Dapeng; Zhao, Qing

2016-10-01

Nanopore-based sensing technology is considered high-throughput and low-cost for single molecule detection, but solid-state nanopores have suffered from pore clogging issues. A simple Tween 20 coating method is applied to ensure long-term (several hours) non-sticky translocation of various types of bio-molecules through SiN nanopores in a wide pH range (4.0-13.0). We also emphasize the importance of choosing appropriate concentration of Tween 20 coating buffer for desired effect. By coating nanopores with a Tween 20 layer, we are able to differentiate between single-stranded DNA and double-stranded DNA, to identify drift-dominated domain for single-stranded DNA, to estimate BSA volume and to observe the shape of individual nucleosome translocation event without non-specific adsorption. The wide pH endurance from 4.0 to 13.0 and the broad types of detection analytes including nucleic acids, proteins, and biological complexes highlight the great application potential of Tween 20-coated solid-state nanopores.

The Structure and Properties of Plasma Sprayed Iron Oxide Doped Manganese Cobalt Oxide Spinel Coatings for SOFC Metallic Interconnectors

NASA Astrophysics Data System (ADS)

Puranen, Jouni; Lagerbom, Juha; Hyvärinen, Leo; Kylmälahti, Mikko; Himanen, Olli; Pihlatie, Mikko; Kiviaho, Jari; Vuoristo, Petri

2011-01-01

Manganese cobalt oxide spinel doped with Fe2O3 was studied as a protective coating on ferritic stainless steel interconnects. Chromium alloying causes problems at high operation temperatures in such oxidizing conditions where chromium compounds evaporate and poison the cathode active area, causing the degradation of the solid oxide fuel cell. In order to prevent chromium evaporation, these interconnectors need a protective coating to block the chromium evaporation and to maintain an adequate electrical conductivity. Thermal spraying is regarded as a promising way to produce dense and protective layers. In the present work, the ceramic Mn-Co-Fe oxide spinel coatings were produced by using the atmospheric plasma spray process. Coatings with low thickness and low amount of porosity were produced by optimizing deposition conditions. The original spinel structure decomposed because of the fast transformation of solid-liquid-solid states but was partially restored by using post-annealing treatment.

Thin Film Solid Lubricant Development

NASA Technical Reports Server (NTRS)

Benoy, Patricia A.

1997-01-01

Tribological coatings for high temperature sliding applications are addressed. A sputter-deposited bilayer coating of gold and chromium is investigated as a potential solid lubricant for protection of alumina substrates during sliding at high temperature. Evaluation of the tribological properties of alumina pins sliding against thin sputtered gold films on alumina substrates is presented.

Ultrasound-assisted magnetic solid-phase extraction based ionic liquid-coated Fe3O4@graphene for the determination of nitrobenzene compounds in environmental water samples.

PubMed

Cao, Xiaoji; Shen, Lingxiao; Ye, Xuemin; Zhang, Feifei; Chen, Jiaoyu; Mo, Weimin

2014-04-21

An ultrasound-assisted magnetic solid-phase extraction procedure with the [C7MIM][PF6] ionic liquid-coated Fe3O4-grafted graphene nanocomposite as the magnetic adsorbent has been developed for the determination of five nitrobenzene compounds (NBs) in environmental water samples, in combination with high performance liquid chromatography-photodiode array detector (HPLC-PDA). Several significant factors that affect the extraction efficiency, such as the types of magnetic nanoparticle and ionic liquid, the volume of ionic liquid and the amount of magnetic nanoparticles, extraction time, ionic strength, and solution pH, were investigated. With the assistance of ultrasound, adsorbing nitrobenzene compounds by ionic liquid and self-aggregating ionic liquid onto the surface of the Fe3O4-grafted graphene proceeded synchronously, which made the extraction achieved the maximum within 20 min using only 144 μL [C7MIM][PF6] and 3 mg Fe3O4-grafted graphene. Under the optimized conditions, satisfactory linearities were obtained for all NBs with correlation coefficients larger than 0.9990. The mean recoveries at two spiked levels ranged from 80.35 to 102.77%. Attributed to the convenient magnetic separation, the Fe3O4-grafted graphene could be recycled many times. The proposed method was demonstrated to be feasible, simple, solvent-saving and easy to operate for the trace analysis of NBs in environmental water samples.

Super-sensitive time-resolved fluoroimmunoassay for thyroid-stimulating hormone utilizing europium(III) nanoparticle labels achieved by protein corona stabilization, short binding time, and serum preprocessing.

PubMed

Näreoja, Tuomas; Rosenholm, Jessica M; Lamminmäki, Urpo; Hänninen, Pekka E

2017-05-01

Thyrotropin or thyroid-stimulating hormone (TSH) is used as a marker for thyroid function. More precise and more sensitive immunoassays are needed to facilitate continuous monitoring of thyroid dysfunctions and to assess the efficacy of the selected therapy and dosage of medication. Moreover, most thyroid diseases are autoimmune diseases making TSH assays very prone to immunoassay interferences due to autoantibodies in the sample matrix. We have developed a super-sensitive TSH immunoassay utilizing nanoparticle labels with a detection limit of 60 nU L -1 in preprocessed serum samples by reducing nonspecific binding. The developed preprocessing step by affinity purification removed interfering compounds and improved the recovery of spiked TSH from serum. The sensitivity enhancement was achieved by stabilization of the protein corona of the nanoparticle bioconjugates and a spot-coated configuration of the active solid-phase that reduced sedimentation of the nanoparticle bioconjugates and their contact time with antibody-coated solid phase, thus making use of the higher association rate of specific binding due to high avidity nanoparticle bioconjugates. Graphical Abstract We were able to decrease the lowest limit of detection and increase sensitivity of TSH immunoassay using Eu(III)-nanoparticles. The improvement was achieved by decreasing binding time of nanoparticle bioconjugates by small capture area and fast circular rotation. Also, we applied a step to stabilize protein corona of the nanoparticles and a serum-preprocessing step with a structurally related antibody.

Carbon nanotubes@silicon dioxide nanohybrids coating for solid-phase microextraction of organophosphorus pesticides followed by gas chromatography-corona discharge ion mobility spectrometric detection.

PubMed

Saraji, Mohammad; Jafari, Mohammad Taghi; Mossaddegh, Mehdi

2016-01-15

A high efficiency solid-phase microextraction (SPME) fiber coated with porous carbon nanotubes-silicon dioxide (CNTs-SiO2) nanohybrids was synthesized and applied for the determination of some organophosphorus pesticides (OPPs) in vegetables, fruits and water samples. Gas chromatography-corona discharge ion mobility spectrometry was used as the detection system. Glucose, as a biocompatible compound, was used for connecting CNT and SiO2 during a hydrothermal process. The electrospinning technique was also applied for the fiber preparation. The parameters affecting the efficiency of extraction, including stirring rate, salt effect, extraction temperature, extraction time, desorption temperature and desorption time, were investigated and optimized. The developed CNTs@SiO2 fiber presented better extraction efficiency than the commercial SPME fibers (PA, PDMS, and PDMS-DVB). The intra- and inter-day relative standard deviations were found to be lower than 6.2 and 9.0%, respectively. For water samples, the limits of detection were in the range of 0.005-0.020 μg L(-1) and the limits of quantification were between 0.010 and 0.050 μg L(-1). The results showed a good linearity in the range of 0.01-3.0 μg L(-1) for the analytes. The spiking recoveries ranged from 79 (± 9) to 99 (± 8). The method was successfully applied for the determination of OPPs in real samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Cetylpyridinium chloride functionalized silica-coated magnetite microspheres for the solid-phase extraction and pre-concentration of ochratoxin A from environmental water samples with high-performance liquid chromatographic analysis.

PubMed

Hu, Meihua; Huang, Pengcheng; Suo, Lili; Wu, Fangying

2017-06-01

A new method based on cetylpyridinium chloride coated ferroferric oxide/silica magnetic microspheres as an efficient solid-phase adsorbent was developed for the extraction and enrichment of ochratoxin A. The determination of ochratoxin A was obtained by high-performance liquid chromatography with fluorescence detection. In the presence of cetylpyridinium chloride, the adsorption capacity of ferroferric oxide/silica microspheres was 5.95 mg/g for ochratoxin A. The experimental parameters were optimized, including the amounts of ferroferric oxide/silica microspheres (20 mg) and cetylpyridinium chloride (0.18 mL, 0.5 mg/mL), pH value of media (9), ultrasonic time (5 min), elution solvent and volume [2(1 + 1) mL (washed twice, 1 mL each time) 1% acetic acid acetonitrile]. Under optimal experiment conditions, ochratoxin A had good linearity in the range of 2.5-250.0 ng/L in water samples with correlation coefficient of the calibration curve 0.9995. The limit of detection for ochratoxin A was 0.83 ng/L, and the recoveries were 89.8-96.8% with the relative standard deviation of 1.5-3.5% in environmental water samples. Furthermore, ferroferric oxide/silica microspheres show excellent reusability during extraction procedures for no less than six times. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of beer volatiles by polymeric imidazolium-solid phase microextraction coatings: Synthesis and characterization of polymeric imidazolium ionic liquids.

PubMed

González-Álvarez, Jaime; Blanco-Gomis, Domingo; Arias-Abrodo, Pilar; Pello-Palma, Jairo; Ríos-Lombardía, Nicolás; Busto, Eduardo; Gotor-Fernández, Vicente; Gutiérrez-Álvarez, María Dolores

2013-08-30

Two polymeric ionic liquids, 3-(but-3″-en-1″-yl)-1-[2'-hydroxycyclohexyl]-1H-imidazol-3-ium bis(trifluoromethanesulfonyl)imide (IL-1) and 1-(2'-hydroxycyclohexyl)-3-(4″-vinylbenzyl)-1H-imidazol-3-ium bis(trifluoromethylsulfonyl)imide (IL-2), have been synthesized by a free radical polymerization reaction and used as coatings for solid-phase microextraction (SPME). These new fibers exhibit good film stability, high thermal stability (270-290°C) and long lifetimes, and are used for the extraction of volatile compounds in lemon beer using gas chromatography separation and flame ionization detection. The scanning electron micrographs of the fiber surface revealed a polymeric ionic liquid (PIL) film, which is distributed homogeneously on the fiber. The developed PIL fiber showed good linearity between 50 and 2000μg/L with regression coefficients in the range of 0.996-0.999. The relative standard deviations (RSD) obtained in the peak area were found to vary between 1% and 12%, which assured that adequate repeatability was achieved. The spiked recoveries for three beer samples ranged from 78.4% to 123.6%. Experimental design has been employed in the optimization of extraction factors and robustness assessment. The polymeric IL-1 butenyl fiber showed a greater efficiency compared to the PDMS-DVB (65μm) and CAR-PDMS (75μm) for the extraction of all of the analytes studied. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Preparation of C18 composite solid-phase microextraction fiber and its application to the determination of organochlorine pesticides in water samples.

PubMed

Li, Siyan; Lu, Chengwei; Zhu, Fang; Jiang, Ruifen; Ouyang, Gangfeng

2015-05-11

In this work, a C18 composite solid-phase microextraction (SPME) fiber was prepared with a new method and applied to the analysis of organochlorine pesticides (OCPs) in water sample. A stainless steel wire (o.d. 127 μm) was used as the substrate, and a mixture of the C18 particle (3.5 μm) and the 184 silicone was used as the coating material. During the process of fiber preparation, a section of capillary column was used to fix the mixture onto the stainless steel wire and to ensure the constant of coating thickness. The prepared fiber showed excellent thermal stability and solvent resistance. By coupling with gas chromatography-mass spectrometry (GC-MS), the fiber exhibited wide linearity (2-500 ng L(-1)) and good sensitivity for the determination of six OCPs in water samples, the OCPs tested included hexachlorobezene, trans-chlordane, cis-chlordane, o,p-DDT, p,p-DDT and mirex. Not only the extraction performance of the newly prepared fiber was more than seven times higher than those of commercial fibers, the limits of detections (LODs) (0.059-0.151 ng L(-1)) for OCPs achieved under optimized conditions were also lower than those of reported SPME methods. The fiber was successfully applied to the determination of OCPs in real water samples by using developed SPME-GC-MS method. Copyright © 2015 Elsevier B.V. All rights reserved.

Molecularly imprinted coated graphene oxide solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of phloxine B in coffee bean.

PubMed

Zhai, Haiyun; Su, Zihao; Chen, Zuanguang; Liu, Zhenping; Yuan, Kaisong; Huang, Lu

2015-03-20

A method was developed to sensitively determine phloxine B in coffee bean by molecularly imprinted polymers (MIPs) coated graphene oxide (GO) solid-phase extraction (GO-MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC-LIF). The GO-MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using GO as supporting material, phloxine B, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade GO-MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions. The GO-MIPs were characterized by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR). The mean recoveries of phloxine B in coffee bean ranged from 89.5% to 91.4% and the intra-day and inter-day relative standard deviation (RSD) values all ranged from 3.6% to 4.7%. Good linearity was obtained over 0.001-2.0 μg mL(-1) (r=0.9995) with the detection limit (S/N=3) of 0.075 ng mL(-1). Under the selected conditions, enrichment factors of over 90-fold were obtained and extraction on the monolithic column effectively cleaned up the coffee bean matrix. The results demonstrated that the proposed GO-MISPE HPLC-LIF method can be applied to sensitively determine phloxine B in coffee bean. Copyright © 2015 Elsevier B.V. All rights reserved.

Fast analysis of glycosides based on HKUST-1-coated monolith solid-phase microextraction and direct analysis in real-time mass spectrometry.

PubMed

Li, Xianjiang; Wang, Xin; Ma, Wen; Ai, Wanpeng; Bai, Yu; Ding, Li; Liu, Huwei

2017-04-01

Glycosides are a kind of highly important natural aromatic precursors in tobacco leaves. In this study, a novel HKUST-1-coated monolith dip-it sampler was designed for the fast and sensitive analysis of trace glycosides using direct analysis in real-time mass spectrometry. This device was prepared in two steps: in situ polymerization of monolith in a glass capillary of dip-it and layer-by-layer growth of HKUST-1 on the surface of monolith. Sufficient extraction was realized by immersing the tip to solution and in situ desorption was carried out by plasma direct analysis in real time. Compared with traditional solid-phase microextraction protocols, sample desorption was not needed anymore, and only extraction conditions were needed to be optimized in this method, including the gas temperature of direct analysis in real time, extraction time, and CH 3 COONH 4 additive concentration. This method enabled the simultaneous detection of six kinds of glycosides with the limits of detection of 0.02-0.05 μg/mL and the linear ranges covering two orders of magnitude with the limits of quantitation of 0.05-0.1 μg/mL. Moreover, the developed method was applied for the glycosides analysis of three tobacco samples, which only took about 2 s for every sample. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Total inorganic arsenic detection in real water samples using anodic stripping voltammetry and a gold-coated diamond thin-film electrode.

PubMed

Song, Yang; Swain, Greg M

2007-06-12

An accurate method for total inorganic arsenic determination in real water samples was developed using differential pulse anodic stripping voltammetry (DPASV) and a Au-coated boron-doped diamond thin-film electrode. Keys to the method are the use of a conducting diamond platform and solid phase extraction for sample preparation. In the method, the As(III) present in the sample is first detected by DPASV. The As(V) present is then reduced to As(III) by reaction with Na2SO3 and this is followed by a second detection of As(III) by DPASV. Interfering metal ions (e.g., Cu(II)) that cause decreased electrode response sensitivity for arsenic in real samples are removed by solid phase extraction as part of the sample preparation. For example, Cu(II) caused a 30% decrease in the As stripping peak current at a solution concentration ratio of 3:1 (Cu(II)/As(III)). This loss was mitigated by passage of the solution through a Chelex 100 cation exchange resin. After passage, only a 5% As stripping current response loss was seen. The effect of organic matter on the Au-coated diamond electrode response for As(III) was also evaluated. Humic acid at a 5 ppm concentration caused only a 9% decrease in the As stripping peak charge for Au-coated diamond. By comparison, a 50% response decrease was observed for Au foil. Clearly, the chemical properties of the diamond surface in the vicinity of the metal deposits inhibit molecular adsorption on at least some of the Au surface. The method provided reproducible and accurate results for total inorganic arsenic in two contaminated water samples provided by the U.S. Bureau of Reclamation. The total inorganic As concentration in the two samples, quantified by the standard addition method, was 23.2+/-2.9 ppb for UV plant influent water and 16.4+/-0.9 ppb for Well 119 water (n=4). These values differed from the specified concentrations by less than 4%.

Determination of UV filters in high ionic strength sample solutions using matrix-compatible coatings for solid-phase microextraction.

PubMed

An, Jiwoo; Anderson, Jared L

2018-05-15

A double-confined polymeric ionic liquid (PIL) sorbent coating was fabricated for the determination of nine ultraviolet (UV) filters in sample solutions containing high salt content by direct immersion solid-phase microextraction (DI-SPME) coupled to high-performance liquid chromatography (HPLC). The IL monomer and crosslinker cations and anions, namely, 1-vinyl-3-decylimidazolium styrenesulfonate ([VImC 10 ][SS]) and 1,12-di(3-vinylbenzylimidazolium) dodecane distyrenesulfonate ([(VBIm) 2 C 12 ] 2[SS]), were co-polymerized to create a highly stable sorbent coating which allowed for up to 120 direct-immersion extractions in 25% NaCl (w/v) solution without a decrease in its extraction capability. Extraction and desorption parameters such as desorption solvent, agitation rate, extraction time, desorption solvent volume, and desorption time were evaluated and optimized. The analytical performance of the styrenesulfonate anion-based PIL fiber, PIL fiber containing chloride anions, and a commercially available polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber were compared. Coefficients of determination (R 2 ) for the styrenesulfonate anion-based PIL fiber ranged from 0.995 to 0.999 and the limits of detection (LODs) varied from 0.1 to 5 µg L -1 . The developed method was successfully applied in real water samples including tap, pool, and lake water, and acceptable relative recovery values were obtained. The lifetime of the PIL fiber containing chloride anions as well as the PDMS/DVB fiber were considerably shorter than the PIL fiber containing the styrenesulfonate anion, with both fibers showing a notable decrease in reproducibility and significant damage to the sorbent coating surface after 40 and 70 extractions, respectively. The R 2 values for the chloride anion containing PIL fiber were at or higher than 0.991 with LODs ranging from 0.5 to 5 µg L -1 . For the PDMS/DVB fiber, R 2 values ranged from 0.992 to 0.999 and LODs were found to be as low as 0.2 µg L -1 and as high as 5 µg L -1 . Copyright © 2018 Elsevier B.V. All rights reserved.

A solid phase microextraction coating based on ionic liquid sol-gel technique for determination of benzene, toluene, ethylbenzene and o-xylene in water samples using gas chromatography flame ionization detector.

PubMed

Sarafraz-Yazdi, Ali; Vatani, Hossein

2013-07-26

Ionic liquid mediated sol-gel sorbents for head-space solid phase microextraction (HS-SPME) were developed for the extraction of benzene, toluene, ethylbenzene and o-xylene (BTEX) compounds from water samples in ultra-trace levels. The analytes were subsequently analyzed with gas chromatography coupled to flame ionization detector (GC-FID). Three different coating fibers were prepared including: poly(dimethylsiloxane) (PDMS), coating prepared from poly(dimethylsiloxane) in the presence of ionic liquid as co-solvent and conditioned at a higher temperature than decomposition temperature of ionic liquid (PDMS-IL-HT) and coating prepared from poly(dimethylsiloxane) in the presence of ionic liquid as co-solvent and conditioned at a lower temperature than decomposition temperature of ionic liquid (PDMS-IL-LT). Prepared fibers demonstrate many advantages such as high thermal and chemical stabilities due to the chemical bonding of the coatings with the silanol groups on the fused-silica surface fiber. These fibers have shown long life time up to 180 extractions. The scanning electron micrographs of the fibers surfaces revealed that addition of ionic liquid into the sol solution during the sol-gel process increases the fiber coating thickness, affects the form of fiber structure and also leaves high pores in the fiber surface that cause high surface area and therefore increases sample capacity of the fibers. The important parameters that affect the extraction efficiency are desorption temperature and time, sample volume, extraction temperature, extraction time, stirring speed and salt effect. Therefore these factors were investigated and optimized. Under optimal conditions, the dynamic linear range with PDMS-IL-HT, PDMS and PDMS-IL-LT fibers were 0.3-200,000; 50-200,000 and 170-150,000pgmL(-1) and the detection limits (S/N=3) were 0.1-2 and 15-200 and 50-500pgmL(-1), and limit of quantifications (S/N=10) were 0.3-8 and 50-700 and 170-1800, respectively. The relative standard deviations (RSD) for one fiber (repeatability) (n=5), were obtained from 3.1 up to 5.4% and between fibers or batch to batch (reproducibility) (n=3) in the range of 3.8-8.5% for three fibers. The developed method was successfully applied to the real water samples while the relative recovery percentages obtained for the spiked water samples at 20pgmL(-1) were from 91.2 to 103.3%. Copyright © 2013 Elsevier B.V. All rights reserved.

Functional nucleic acid entrapment in sol-gel derived materials.

PubMed

Carrasquilla, Carmen; Brennan, John D

2013-10-01

Functional nucleic acids (FNAs) are single-stranded DNA or RNA molecules, typically generated through in vitro selection, that have the ability to act as receptors for target molecules (aptamers) or perform catalysis of a chemical reaction (deoxyribozymes and ribozymes). Fluorescence-signaling aptamers and deoxyribozymes have recently emerged as promising biological recognition and signaling elements, although little has been done to evaluate their potential for solid-phase assays, particularly with species made of RNA due to their lack of chemical stability and susceptibility to nuclease attack. Herein, we present a detailed overview of the methods utilized for solid-phase immobilization of FNAs using a sol-gel entrapment method that can provide protection from nuclease degradation and impart long-term chemical stability to the FNA reporter systems, while maintaining their signaling capabilities. This article will also provide a brief review of the results of such entrapment studies involving fluorescence-signaling versions of a DNA aptamer, selected RNA-cleaving deoxyribozymes, and two different RNA aptamers in a series of sol-gel derived composites, ranging from highly polar silica to hydrophobic methylsilsesquioxane-based materials. Given the ability to produce sol-gel derived materials in a variety of configurations, particularly as thin film coatings on electrodes, optical fibers, and other devices, this entrapment method should provide a useful platform for numerous solid-phase FNA-based biosensing applications. Copyright © 2013 Elsevier Inc. All rights reserved.

Thermal Barrier Coatings Resistant to Glassy Deposits

NASA Astrophysics Data System (ADS)

Drexler, Julie Marie

Engineering of alloys has for years allowed aircraft turbine engines to become more efficient and operate at higher temperatures. As advancements in these alloy systems have become more difficult, ceramic thermal barrier coatings (TBCs), often yttria (7 wt %) stabilized zirconia (7YSZ), have been utilized for thermal protection. TBCs have allowed for higher engine operating temperatures and better fuel efficiency but have also created new engineering problems. Specifically, silica based particles such as sand and volcanic ash that enter the engine during operation form glassy deposits on the TBCs. These deposits can cause the current industrial 7YSZ thermal barrier coatings to fail since the glass formed penetrates and chemically interacts with the TBC. When this occurs, coating failure may occur due to a loss of strain tolerance, which can lead to fracture, and phase changes of the TBC material. There have been several approaches used to stop calcium-magnesium aluminio-silcate (CMAS) glasses (molten sand) from destroying the entire TBC, but overall there is still limited knowledge. In this thesis, 7YSZ and new TBC materials will be examined for thermochemical and thermomechanical performance in the presence of molten CMAS and volcanic ash. Two air plasma sprayed TBCs will be shown to be resistant to volcanic ash and CMAS. The first type of coating is a modified 7YSZ coating with 20 mol% Al2O3 and 5 mol% TiO2 in solid solution (YSZ+20Al+5Ti). The second TBC is made of gadolinium zirconate. These novel TBCs impede CMAS and ash penetration by interacting with the molten CMAS or ash and drastically changing the chemistry. The chemically modified CMAS or ash will crystallize into an apatite or anorthite phase, blocking the CMAS or ash from further destroying the coating. A presented mechanism study will show these coatings are effective due to the large amount of solute (Gd, Al) in the zirconia structure, which is the key to creating the crystalline apatite or anorthite phases. In fact, it will be shown that if the industrial standard 7YSZ coatings contained more Y2O3 they would be very effective in stopping CMAS penetration. Lastly, thermal cyclic testing of 7YSZ and YSZ+20Al+5Ti TBCs reveals that partially CMAS-impregnated TBCs can survive mechanically if cycled in thermal gradient while in most isothermal tests they would fail. Since parts in a jet engine are in a thermal gradient, this type of testing should be performed on future CMAS resistant TBCs.

Abrasion resistant coating and method of making the same

DOEpatents

Sordelet, Daniel J.; Besser, Matthew F.

2001-06-05

An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al--Cu--Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

Surface phase behavior and microstructure of lipid/PEG-emulsifier monolayer-coated microbubbles.

PubMed

Borden, Mark A; Pu, Gang; Runner, Gabriel J; Longo, Marjorie L

2004-06-01

Langmuir trough methods and fluorescence microscopy were combined to investigate the phase behavior and microstructure of monolayer shells coating micron-scale bubbles (microbubbles) typically used in biomedical applications. The monolayer shell consisted of a homologous series of saturated acyl chain phospholipids and an emulsifier containing a single hydrophobic stearate chain and polyethylene glycol (PEG) head group. PEG-emulsifier was fully miscible with expanded phase lipids and phase separated from condensed phase lipids. Phase coexistence was observed in the form of dark condensed phase lipid domains surrounded by a sea of bright, emulsifier-rich expanded phase. A rich assortment of condensed phase area fractions and domain morphologies, including networks and other novel structures, were observed in each batch of microbubbles. Network domains were reproduced in Langmuir monolayers under conditions of heating-cooling followed by compression-expansion, as well as in microbubble shells that underwent surface flow with slight compression. Domain size decreased with increased cooling rate through the phase transition temperature, and domain branching increased with lipid acyl chain length at high cooling rates. Squeeze-out of the emulsifier at a surface pressure near 35 mN/m was indicated by a plateau in Langmuir isotherms and directly visualized with fluorescence microscopy, although collapse of the solid lipid domains occurred at much higher surface pressures. Compression of the monolayer past the PEG-emulsifier squeeze-out surface pressure resulted in a dark shell composed entirely of lipid. Under certain conditions, the PEG-emulsifier was reincorporated upon subsequent expansion. Factors that affect shell formation and evolution, as well as implications for the rational design of microbubbles in medical applications, are discussed.

A New Type of Self-lubricated Thermal Spray Coatings: Liquid Lubricants Embedded in a Metal Matrix

NASA Astrophysics Data System (ADS)

Espallargas, N.; Armada, S.

2015-01-01

Oils and greases are commonly used for lubricating, rotating and sliding systems such as bearings, gears, connectors, etc. The maintenance of such lubricated systems in some applications where access is difficult (e.g., offshore wind farms and subsea equipment) increases the operational costs. In some cases, it can be thought that the use of solid lubricants (MoS2, PTFE, graphite, etc.) embedded in coatings could be a solution for such applications; however, the mechanical and dynamic conditions of most of the systems are not appropriate for solid lubricants. Despite this, solid lubricants such as PTFE and MoS2 have been largely employed in different industries, especially in those applications where liquid lubricants cannot be used and when the dynamic conditions allow for it. Self-lubricated coatings have been a major topic of interest in thermal spray in the last decades. Although the use of liquid lubricants is desirable whenever it is possible, limited research has been addressed toward the development of self-lubricated coatings containing liquid lubricants. One of the main reasons for this is due to the complexity of embedding liquid lubricant reservoirs inside the coating matrix. In the present work, a new type of liquid-solid self-lubricated coatings is presented, being the matrix a metal alloy. Three thermal spray techniques used were as follows: arc-spray, plasma spray, and HVOAF. The metal matrices were two stainless steel types and liquid lubricant-filled capsules with different liquid contents were used. No degradation of the capsules during spraying was observed and the coatings containing capsules were able to keep a low coefficient of friction. The optimal performance is found for the coatings obtained at the lowest spraying temperature and velocity.

Post-Plasma SiOx Coatings of Metal and Metal Oxide Nanoparticles for Enhanced Thermal Stability and Tunable Photoactivity Applications

PubMed Central

Post, Patrick; Jidenko, Nicolas; Weber, Alfred P.; Borra, Jean-Pascal

2016-01-01

The plasma-based aerosol process developed for the direct coating of particles in gases with silicon oxide in a continuous chemical vapor deposition (CVD) process is presented. It is shown that non-thermal plasma filaments induced in a dielectric barrier discharge (DBD) at atmospheric pressure trigger post-DBD gas phase reactions. DBD operating conditions are first scanned to produce ozone and dinitrogen pentoxide. In the selected conditions, these plasma species react with gaseous tetraethyl orthosilicate (TEOS) precursor downstream of the DBD. The gaseous intermediates then condense on the surface of nanoparticles and self-reactions lead to homogeneous solid SiOx coatings, with thickness from nanometer to micrometer. This confirms the interest of post-DBD injection of the organo-silicon precursor to achieve stable production of actives species with subsequent controlled thickness of SiOx coatings. SiOx coatings of spherical and agglomerated metal and metal oxide nanoparticles (Pt, CuO, TiO2) are achieved. In the selected DBD operating conditions, the thickness of homogeneous nanometer sized coatings of spherical nanoparticles depends on the reaction duration and on the precursor concentration. For agglomerates, operating conditions can be tuned to cover preferentially the interparticle contact zones between primary particles, shifting the sintering of platinum agglomerates to much higher temperatures than the usual sintering temperature. Potential applications for enhanced thermal stability and tunable photoactivity of coated agglomerates are presented. PMID:28335219

Wear behaviour of wear-resistant adaptive nano-multilayered Ti-Al-Mo-N coatings

NASA Astrophysics Data System (ADS)

Sergevnin, V. S.; Blinkov, I. V.; Volkhonskii, A. O.; Belov, D. S.; Kuznetsov, D. V.; Gorshenkov, M. V.; Skryleva, E. A.

2016-12-01

Coating samples in the Ti-Al-Mo-N system were obtained by arc-PVD method at variable bias voltage Ub applied to the substrate, and the partial pressure of nitrogen P(N2) used as a reaction gas. The deposited coatings were characterized by a nanocrystalline structure with an average grain size of 30-40 nm and multilayered architecture with alternating layers of (Ti,Al)N nitride and Mo-containing phases with a thickness comparable to the grain size. Coatings of (Ti,Al)N-Mo-Mo2N and (Ti,Al)N-Mo2N compositions were obtained by changing deposition parameters. The obtained coatings had hardness of 40 GPa and the relative plastic deformation under microindentation up to 60%. (Ti,Al)N-Mo2N coatings demonstrated better physicomechanical characteristics, showing high resistance to crack formation and destruction through the plastic deformation mechanism without brittle fracturing, unlike (Ti,Al)N-Mo-Mo2N. The friction coefficient of the study coatings (against Al2O3 balls under dry condition using a pin-on-disc method) reached the values of 0.35 and 0.5 at 20 °C and 500 °C respectively, without noticeable wear within this temperature range. These tribological properties were achieved by forming MoO3 acting as a solid lubricant. At higher temperatures the deterioration in the tribological properties is due to the high rate of MoO3 sublimation from friction surfaces.

Determination of Pyrethroids in Tea Brew by GC-MS Combined with SPME with Multiwalled Carbon Nanotube Coated Fiber.

PubMed

Ren, Dongxia; Sun, Chengjun; Ma, Guanqun; Yang, Danni; Zhou, Chen; Xie, Jiayu; Li, Yongxin

2018-01-01

A new method has been developed to simultaneously determine 7 pyrethroid residues in tea brew using gas chromatography-mass spectrometry (GC-MS) combined with solid phase microextraction (SPME) with multiwalled carbon nanotubes (MWCNTs) coated fiber. The MWCNTs coated fiber of SPME was homemade by using stainless steel wire as coating carrier and polyacrylonitrile (PAN) solution as adhesive glue. Under the optimized conditions, a good linearity was shown for bifenthrin, fenpropathrin, permethrin, and cyfluthrin in 1-50 ng mL -1 and for cypermethrin, fenvalerate, and deltamethrin in 5-50 ng mL -1 . The correlation coefficients were in the range of 0.9948-0.9999. The average recoveries of 7 pyrethroids were 94.2%-107.3% and the relative standard deviations (RSDs) were less than 15%. The detection limit of the method ranged from 0.12 to 1.65 ng mL -1 . The tea brew samples made from some commercial tea samples were analyzed. Among them, bifenthrin, fenpropathrin, and permethrin were found. The results show that the method is rapid and sensitive and requires low organic reagent consumption, which can be well used for the detection of the pyrethroids in tea brew.

Simultaneous determination of ochratoxin A and cyclopiazonic, mycophenolic, and tenuazonic acids in cornflakes by solid-phase microextraction coupled to high-performance liquid chromatography.

PubMed

Aresta, Antonella; Cioffi, Nicola; Palmisano, Francesco; Zambonin, Carlo G

2003-08-27

A solid-phase microextraction (SPME) method, coupled to liquid chromatography with diode array UV detection (LC-UV/DAD), for the simultaneous determination of cyclopiazonic acid, mycophenolic acid, tenuazonic acid, and ochratoxin A is described. Chromatographic separation was achieved on a propylamino-bonded silica gel stationary phase using acetonitrile/methanol/ammonium acetate buffer mixture (78:2:20, v/v/v) as mobile phase. SPME adsorption and desorption conditions were optimized using a silica fiber coated with a 60 microm thick polydimethylsiloxane/divinylbenzene film. Estimated limits of detection and limits of quantitation ranged from 3 to 12 ng/mL and from 7 to 29 ng/mL, respectively. The method has been applied to cornflake samples. Samples were subjected to a preliminary short sonication in MeOH/2% KHCO(3) (70:30, v/v); the mixture was evaporated to near dryness and reconstituted in 1.5 mL of 5 mM phosphate buffer (pH 3) for SPME followed by LC-UV/DAD. The overall procedure had recoveries (evaluated on samples spiked at 200 ng/g level) ranging from 74 +/- 4 to 103 +/- 9%. Samples naturally contaminated with cyclopiazonic and tenuazonic acids were found; estimated concentrations were 72 +/- 9 and 25 +/- 6 ng/g, respectively.

Analysis of tricyclic antidepressant drugs in plasma by means of solid-phase microextraction-liquid chromatography-mass spectrometry.

PubMed

Alves, Claudete; Santos-Neto, Alvaro J; Fernandes, Christian; Rodrigues, José C; Lanças, Fernando M

2007-10-01

Solid-phase microextraction coupled to liquid chromatography and mass spectrometry (SPME-LC-MS) was used to analyze tricyclic antidepressant drugs desipramine, imipramine, nortriptyline, amitriptyline, and clomipramine (internal standard) in plasma samples. SPME was performed by direct extraction on a PDMS/DVB (60 microm) coated fiber, employing a stirring rate of 1200 rpm for 30 min, pH 11.0, and temperature of 30 degrees C. Drug desorption was carried out by exposing the fiber to the liquid chromatography mobile phase for 20 min, using a labmade SPME-LC interface at 50 degrees C. The main variables experimentally influencing LC-MS response were evaluated and mathematically modeled. A rational optimization with fewer experiments was achieved using a factorial design approach. The constructed empirical models were adjusted with 96-98% of explained deviation allowing an adequate data set comprehension. The chromatographic separation was realized using an RP-18 column (150 mm x 2.1 mm, 5 microm particles) and ammonium acetate buffer (0.01 mol/l, pH 5.50) : acetonitrile (50 : 50 v/v) as mobile phase. Low detection levels were achieved with electrospray interface (0.1 ng/ml). The developed method showed specificity, linearity, precision, and limit of quantification adequate to assay tricyclic antidepressant drugs in plasma.

Atomic Layer Deposition for the Conformal Coating of Nanoporous Materials

DOE PAGES

Elam, Jeffrey W.; Xiong, Guang; Han, Catherine Y.; ...

2006-01-01

Amore » tomic layer deposition ( LD ) is ideal for applying precise and conformal coatings over nanoporous materials. We have recently used LD to coat two nanoporous solids: anodic aluminum oxide ( O ) and silica aerogels. O possesses hexagonally ordered pores with diameters d ∼ 40 nm and pore length L ∼ 70 microns. The O membranes were coated by LD to fabricate catalytic membranes that demonstrate remarkable selectivity in the oxidative dehydrogenation of cyclohexane. dditional O membranes coated with LD Pd films show promise as hydrogen sensors. Silica aerogels have the lowest density and highest surface area of any solid material. Consequently, these materials serve as an excellent substrate to fabricate novel catalytic materials and gas sensors by LD .« less

Coating solid dispersions on microneedles via a molten dip coating method: development and in vitro evaluation for transdermal delivery of a water insoluble drug

PubMed Central

Ma, Yunzhe; Gill, Harvinder S.

2014-01-01

This study demonstrates for the first time the ability to coat solid dispersions on microneedles as a means to deliver water-insoluble drugs through the skin. Polyethylene glycol (PEG) was selected as the hydrophilic matrix, and lidocaine base was selected as the model hydrophobic drug to create the solid dispersion. First, thermal characterization and viscosity measurements of the PEG-lidocaine mixture at different mass fractions were performed. The results show that lidocaine can remain stable at temperatures up to ~130 °C, and that viscosity of the PEG-lidocaine molten solution increases as the mass fraction of lidocaine decreases. Differential scanning calorimetry demonstrated that at lidocaine mass fraction less than or equal to 50%, lidocaine is well dispersed in the PEG-lidocaine mixture. Uniform coatings were obtained on microneedle surfaces. In vitro dissolution studies in porcine skin showed that microneedles coated with PEG-lidocaine dispersions resulted in significantly higher delivery of lidocaine in just 3 min compared to 1 h topical application of 0.15 g EMLA®, a commercial lidocaine-prilocaine cream. In conclusion, the molten coating process we introduce here offers a practical approach to coat water-insoluble drugs on microneedles for transdermal delivery. PMID:25213295

Robotic weld overlay coatings for erosion control

NASA Astrophysics Data System (ADS)

The erosion of materials by the impact of solid particles has received increasing attention during the past twenty years. Recently, research has been initiated with the event of advanced coal conversion processes in which erosion plays an important role. The resulting damage, termed Solid Particle Erosion (SPE), is of concern primarily because of the significantly increased operating costs which result in material failures. Reduced power plant efficiency due to solid particle erosion of boiler tubes and waterfalls has led to various methods to combat SPE. One method is to apply coatings to the components subjected to erosive environments. Protective weld overlay coatings are particularly advantageous in terms of coating quality. The weld overlay coatings are essentially immune to spallation due to a strong metallurgical bond with the substrate material. By using powder mixtures, multiple alloys can be mixed in order to achieve the best performance in an erosive environment. However, a review of the literature revealed a lack of information on weld overlay coating performance in erosive environments which makes the selection of weld overlay alloys a difficult task. The objective of this project is to determine the effects of weld overlay coating composition and microstructure on erosion resistance. These results will lead to a better understanding of erosion mitigation in CFB's.

40 CFR 59.406 - Compliance provisions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... exception of low solids stains and low solids wood preservatives, determine the VOC content in grams of VOC...: VOC content = grams of VOC per liter of coating Ws = weight of volatiles, in grams Ww = weight of water, in grams Wec = weight of exempt compounds, in grams Vm = volume of coating, in liters Vw = volume...

40 CFR 59.406 - Compliance provisions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... exception of low solids stains and low solids wood preservatives, determine the VOC content in grams of VOC...: VOC content = grams of VOC per liter of coating Ws = weight of volatiles, in grams Ww = weight of water, in grams Wec = weight of exempt compounds, in grams Vm = volume of coating, in liters Vw = volume...

40 CFR 59.406 - Compliance provisions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... exception of low solids stains and low solids wood preservatives, determine the VOC content in grams of VOC...: VOC content = grams of VOC per liter of coating Ws = weight of volatiles, in grams Ww = weight of water, in grams Wec = weight of exempt compounds, in grams Vm = volume of coating, in liters Vw = volume...

40 CFR 59.406 - Compliance provisions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... exception of low solids stains and low solids wood preservatives, determine the VOC content in grams of VOC...: VOC content = grams of VOC per liter of coating Ws = weight of volatiles, in grams Ww = weight of water, in grams Wec = weight of exempt compounds, in grams Vm = volume of coating, in liters Vw = volume...

40 CFR 59.406 - Compliance provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... exception of low solids stains and low solids wood preservatives, determine the VOC content in grams of VOC...: VOC content = grams of VOC per liter of coating Ws = weight of volatiles, in grams Ww = weight of water, in grams Wec = weight of exempt compounds, in grams Vm = volume of coating, in liters Vw = volume...

Solid-water detoxifying reagents for chemical and biological agents

DOEpatents

Hoffman, Dennis M [Livermore, CA; Chiu, Ing Lap [Castro Valley, CA

2006-04-18

Formation of solid-water detoxifying reagents for chemical and biological agents. Solutions of detoxifying reagent for chemical and biological agents are coated using small quantities of hydrophobic nanoparticles by vigorous agitation or by aerosolization of the solution in the presence of the hydrophobic nanoparticles to form a solid powder. For example, when hydrophobic fumed silica particles are shaken in the presence of IN oxone solution in approximately a 95:5-weight ratio, a dry powder results. The hydrophobic silica forms a porous coating of insoluble fine particles around the solution. Since the chemical or biological agent tends to be hydrophobic on contact with the weakly encapsulated detoxifying solution, the porous coating breaks down and the detoxifying reagent is delivered directly to the chemical or biological agent for maximum concentration at the point of need. The solid-water (coated) detoxifying solutions can be blown into contaminated ventilation ducting or other difficult to reach sites for detoxification of pools of chemical or biological agent. Once the agent has been detoxified, it can be removed by flushing the area with air or other techniques.

Gd, I-doped TiO2 thin films coated on solid waste material: synthesis, characterization, and photocatalytic activity under UV or visible light irradiation

NASA Astrophysics Data System (ADS)

Deng, Siwei; Yu, Jiang; Yang, Chun; Chang, Jiahua; Wang, Yizheng; Wang, Ping; Xie, Shiqian

2017-10-01

In this work, titanium dioxide thin films doped with different concentrations of gadolinium (Gd) and iodine (I) were synthesized using the sol-gel method and successfully coated on solid waste material (made in our lab) by dipping, resulting in the titanium dioxide thin-film-coated material (TiO2M). Then, the doped titanium dioxide thin films were characterized by X-ray diffraction (XRD), SEM, and UV-Vis spectroscopy; the optimum coating cycle was evaluated by removal rates of COD and ammonia nitrogen in raw wastewater and secondary effluent. Moreover, the photocatalytic activity was determined by degradation efficiency of methyl orange. The results showed that TiO2M had desirable reusability and the photocatalytic activity was attractive under ultraviolet light irradiation. Furthermore, it is found that the amount of dopant in TiO2 was a key parameter in increasing the photoactivity. 1% Gd-doped TiO2M exhibited the best photocatalytic activity for the degradation of methyl orange with the removal rate reaching 85.55%. The result was in good agreement with the observed smaller crystallite size and profitable crystal structure (anatase phase). Besides, the TiO2M (0.8% Gd-doped TiO2M, 1% Gd-doped TiO2M, 10% I-doped TiO2M, and 5% I-1% Gd-doped TiO2M) with desirable photocatalytic activity at ultraviolet light irradiation was selected for the visible light photocatalytic experiments with taking methyl orange as the target pollutants. The results showed that all of them exhibited the similar photocatalytic activity after 7 h of sunlight irradiation (around 90% removal effect). In general, this research developed a very effective and environmentally friendly photocatalyst for pollutant degradation.

MEMS reagent and sample handling procedure: Feasibility of viral antibody detection by passive immune agglutination

NASA Technical Reports Server (NTRS)

Bailey, G. D.; Tenoso, H. J.

1975-01-01

An attempt was made to develop a test requiring no preadsorption steps for the assessment of antibodies to rubella and mumps viruses using the passive immune agglutination (PIA) method. Both rubella and mumps antigens and antibodies were prepared. Direct PIA tests, using rubella antigen-coated beads, and indirect PIA tests, using rubella antibody-coated beads, were investigated. Attempts, using either method, were unsuccessful. Serum interference along with nonspecific agglutination of beads by the rubella antigen resulted in no specific response under the test conditions investigated. A new, highly sensitive approach, the enzyme immunoassay (EIA) test system, is recommended to overcome the nonspecificity. This system is a logical outgrowth of some of the solid phase work done on MEMS and represents the next generation tests system that can be directly applied to early disease detection and monitoring.

Barrier coated drug layered particles for enhanced performance of amorphous solid dispersion dosage form.

PubMed

Puri, Vibha; Dantuluri, Ajay K; Bansal, Arvind K

2012-01-01

Amorphous solid dispersions (ASDs) may entail tailor-made dosage form design to exploit their solubility advantage. Surface phenomena dominated the performance of amorphous celecoxib solid dispersion (ACSD) comprising of amorphous celecoxib (A-CLB), polyvinylpyrrolidone, and meglumine (7:2:1, w/w). ACSD cohesive interfacial interactions hindered its capsule dosage form dissolution (Puri V, Dhantuluri AK, Bansal AK 2011. J Pharm Sci 100:2460-2468). Furthermore, ACSD underwent significant devitrification under environmental stress. In the present study, enthalpy relaxation studies revealed its free surface to contribute to molecular mobility. Based on all these observations, barrier coated amorphous CLB solid dispersion layered particles (ADLP) were developed by Wurster process, using microcrystalline cellulose as substrate and polyvinyl alcohol (PVA), inulin, and polyvinyl acetate phthalate (PVAP) as coating excipients. Capsule formulations of barrier coated-ADLP could achieve rapid dispersibility and high drug release. Evaluation under varying temperature and RH conditions suggested the crystallization inhibitory efficiency in order of inulin < PVA ≈ PVAP; however, under only temperature treatment, crystallization inhibition increased with increase in T(g) of the coating material. Simulated studies using DSC evidenced drug-polymer mixing at the interface as a potential mechanism for surface stabilization. In conclusion, surface modification yielded a fast dispersing robust high drug load ASD based dosage form. Copyright © 2011 Wiley-Liss, Inc.

Spin coating of electrolytes

DOEpatents

Stetter, Joseph R.; Maclay, G. Jordan

1989-01-01

Methods for spin coating electrolytic materials onto substrates are disclosed. More particularly, methods for depositing solid coatings of ion-conducting material onto planar substrates and onto electrodes are disclosed. These spin coating methods are employed to fabricate electrochemical sensors for use in measuring, detecting and quantifying gases and liquids.

Anthocyanins, phenolics and antioxidant capacity after fresh storage of blueberry treated with edible coatings.

PubMed

Chiabrando, Valentina; Giacalone, Giovanna

2015-05-01

The influence of different edible coatings on total phenolic content, total anthocyanin and antioxidant capacity in highbush blueberry (Vaccinium corymbosum L. cv Berkeley and O'Neal) was investigated, mainly for industrial applications. Also titratable acidity, soluble solids content, firmness and weight loss of berries were determined at harvest and at 15-day intervals during 45 storage days at 0 °C, in order to optimize coating composition. Application of chitosan coating delayed the decrease in anthocyanin content, phenolic content and antioxidant capacity. Coating samples showed no significant reduction in the weight loss during storage period. In cv Berkeley, the use of alginate coating showed a positive effect on firmness, titratable acidity and maintained surface lightness of treated berries. In cv O'Neal, no significant differences in total soluble solids content were found, and the chitosan-coated berries showed the minimum firmness losses. In both cultivars, the addition of chitosan to coatings decreases the microbial growth rate.

Experimental test program for evaluation of solid lubricant coating as applied to compliant foil gas bearings to 315 deg C

NASA Technical Reports Server (NTRS)

Wagner, R. C.

1985-01-01

An experimental apparatus and test procedure was developed to compare the performance of two solid lubricant coatings for air lubricated compliant foil gas bearings in the temperature range of 25 to 315 C. Polyimide bonded additive (SBGC) were tested extensively for durability and frictional characteristics. A partial arc bearing constructed of Inconel X-750 was coated on the bore with one of these coatings. The foil was subjected to repeated start/stop cycles. Performance comparisons reveal that although both coatings survive thousands of start/stop cycles, only the PBGF coated bearing achieves the specified 9000 start/stops. There is enough wear on the SBGC coated bearing to warrant termination of the test prior to 9000 start/stop cycles due to coating failure. The frictional characteristics of the PBGF are better at the elevated temperatures than at lower temperatures; a marked increase in sliding friction occurs as the temperature decreases. The SBGC maintains relatively constant frictional characteristics independent of operating temperature.

Effect of 2D WS2 Addition on Cold-Sprayed Aluminum Coating

NASA Astrophysics Data System (ADS)

Loganathan, Archana; Rengifo, Sara; Hernandez, Alexander Franco; Emirov, Yusuf; Zhang, Cheng; Boesl, Benjamin; Karthikeyan, Jeganathan; Agarwal, Arvind

2017-10-01

Tungsten disulfide (WS2) has excellent solid lubrication properties due to its 2D layered structure. This study focuses on depositing Al-2 wt.% WS2 composite coating by cold spray technique. The effect of WS2 addition on the microstructure, mechanical and tribological properties of the composite coatings is examined in the as-deposited and heat-treated conditions. After heat treatment, the coating density increased to 99% with improved intersplat bonding. The microhardness of the heat-treated Al-2 wt.% WS2 coating increased by 56% as compared to the as-sprayed coating. The wear resistance of heat-treated Al-2 wt.% WS2 coating improved by 75% with a synergistic reduction in the coefficient of friction (COF) by 51%. Transmission electron microscopy investigation reveals the presence of layered WS2 within aluminum splats with a strong interface. This study shows that cold spraying can be effectively used to integrate 2D layered WS2 as a solid lubricant in the metallic coatings.

Solid phase extraction of magnetic carbon doped Fe3O4 nanoparticles.

PubMed

Yang, Jing; Li, Jia-yuan; Qiao, Jun-qin; Lian, Hong-zhen; Chen, Hong-yuan

2014-01-17

Carbon decorated Fe3O4 nanoparticles (Fe3O4/C) are promising magnetic solid-phase extraction (MSPE) sorbents in environmental and biological analysis. Fe3O4/C based MSPE method shows advantages of easy operation, rapidness, high sensitivity, and environmental friendliness. In this paper, the MSPE mechanism of Fe3O4/C nanoparticles has been comprehensively investigated, for the first time, through the following three efforts: (1) the comparison of extraction efficiency for polycyclic aromatic hydrocarbons (PAHs) between the Fe3O4/C sorbents and activated carbon; (2) the chromatographic retention behaviors of hydrophobic and hydrophilic compounds on Fe3O4/C nanoparticles as stationary phase; (3) related MSPE experiments for several typical compounds such as pyrene, naphthalene, benzene, phenol, resorcinol, anisole and thioanisole. It can be concluded that there are hybrid hydrophobic interaction and hydrogen bonding interaction or dipole-dipole attraction between Fe3O4/C sorbents and analytes. It is the existence of carbon and oxygen-containing functional groups coated on the surface of Fe3O4/C nanoparticles that is responsible for the effective extraction process. Copyright © 2013 Elsevier B.V. All rights reserved.

Magnetic solid phase extraction with CoFe2O4/oleic acid nanoparticles coupled to gas chromatography-mass spectrometry for the determination of alkylphenols in baby foods.

PubMed

Pastor-Belda, Marta; Viñas, Pilar; Campillo, Natalia; Hernández-Córdoba, Manuel

2017-04-15

Magnetic solid phase extraction (MSPE) with cobalt ferrite nanoparticles coated with oleic acid is described for the determination of alkylphenols (APs), 4-tert-butylphenol (TBP), 4-pentylphenol (PP), 4-hexylphenol (HP), 4-tert-octylphenol (TOP), 4-n-octylphenol (OP) and 4-nonylphenol (NP) in baby foods using gas chromatography with mass spectrometry (GC-MS). Prior to MSPE, the sample was treated with trichloroacetic acid, and the APs derivatized with acetic anhydride. Parameters affecting the extraction efficiency: amount of magnetic nanoparticles, extraction time and desorption conditions, were optimized. The enriched phase obtained was evaporated to dryness and the residue reconstituted in 50μL of methanol, 1μL of which was injected into the GC-MS. Samples were quantified applying matrix-matched calibration and using 2-chloro-5-bromoanisole as surrogate standard. The analysis of 0.5g of sample provided detection limits in the 0.4-1.7ngg -1 range. Some samples contained APs at levels of between 3ngg -1 for HP and 122ngg -1 for TOP. Copyright © 2016 Elsevier Ltd. All rights reserved.

Low acetaldehyde collection efficiencies for 24-hour sampling with 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents.

PubMed

Herrington, Jason S; Fan, Zhi-Hua Tina; Lioy, Paul J; Zhang, Junfeng Jim

2007-01-15

Airborne aldehyde and ketone (carbonyl) sampling methodologies based on derivatization with 2,4-dinitrophenylhydrazine (DNPH)-coated solid sorbents could unequivocally be considered the "gold" standard. Originally developed in the late 1970s, these methods have been extensively evaluated and developed up to the present day. However, these methods have been inadequately evaluated for the long-term (i.e., 24 h or greater) sampling collection efficiency (CE) of carbonyls other than formaldehyde. The current body of literature fails to demonstrate that DNPH-coated solid sorbent sampling methods have acceptable CEs for the long-term sampling of carbonyls other than formaldehyde. Despite this, such methods are widely used to report the concentrations of multiple carbonyls from long-term sampling, assuming approximately 100% CEs. Laboratory experiments were conducted in this study to evaluate the long-term formaldehyde and acetaldehyde sampling CEs for several commonly used DNPH-coated solid sorbents. Results from sampling known concentrations of formaldehyde and acetaldehyde generated in a dynamic atmosphere generation system demonstrate that the 24-hour formaldehyde sampling CEs ranged from 83 to 133%, confirming the findings made in previous studies. However, the 24-hour acetaldehyde sampling CEs ranged from 1 to 62%. Attempts to increase the acetaldehyde CEs by adding acid to the samples post sampling were unsuccessful. These results indicate that assuming approximately 100% CEs for 24-hour acetaldehyde sampling, as commonly done with DNPH-coated solid sorbent methods, would substantially under estimate acetaldehyde concentrations.

Anthracite-Derived Dual-Phase Carbon-Coated Li3V2(PO4)3 as High-Performance Cathode Material for Lithium Ion Batteries.

PubMed

Ding, Xiao-Kai; Zhang, Lu-Lu; Yang, Xue-Lin; Fang, Hui; Zhou, Ying-Xian; Wang, Ji-Qing; Ma, Di

2017-12-13

In this study, low cost anthracite-derived dual-phase carbon-coated Li 3 V 2 (PO 4 ) 3 composites have been successfully prepared via a traditional solid-phase method. XRD results show that the as-prepared samples have high crystallinity and anthracite introduction has no influence on the LVP crystal structure. The LVP/C particles are uniformly covered with a dual-phase carbon layer composed of amorphous carbon and graphitic carbon. The effect of the amount of anthracite on the battery performance of LVP as a cathode material has also been studied. The LVP/C composite obtained with 10 wt % anthracite (LVP/C-10) delivers the highest initial charge/discharge capacities of 186.1/168.2 mAh g -1 at 1 C and still retains the highest discharge capacity of 134.0 mAh g -1 even after 100 cycles. LVP/C-10 also displays an outstanding average capacity of 140.8 mAh g -1 at 5 C. The superior rate capability and cycling stability of LVP/C-10 is ascribed to the reduced particle size, decreased charge-transfer resistance, and improved lithium ion diffusion coefficient. Our results demonstrate that using anthracite as a carbon source opens up a new strategy for larger-scale synthesis of LVP and other electrode materials with poor electronic conductivity for lithium ion batteries.

Phase analysis of plasma-sprayed zirconia-yttria coatings

NASA Technical Reports Server (NTRS)

Shankar, N. R.; Berndt, C. C.; Herman, H.

1983-01-01

Phase analysis of plasma-sprayed 8 wt pct-yttria-stabilized zirconia (YSZ) thermal barrier coatings and powders was carried out by X-ray diffraction. Step scanning was used for increased peak resolution. Plasma spraying of the YSZ powder into water or onto a steel substrate to form a coating reduced the cubic and monoclinic phases with a simultaneous increase in the tetragonal phase. Heat treatment of the coating at 1150 C for 10 h in an Ar atmosphere increased the amount of cubic and monoclinic phases. The implications of these transformations on coating performance and integrity are discussed.

The properties of LaSrМnO3 powders synthesized at various regimes

NASA Astrophysics Data System (ADS)

Mikhailov, M.; Sokolovskiy, A.; Vlasov, V.; Smolin, A.

2017-09-01

For the first time the concentration of ferromagnetic and paramagnetic phases in LaSrMnO3 compounds has been defined using diffuse reflection and absorption spectra in the visible and near-infrared regions. The compounds as powders were synthesized by heating La2O3/SrCO3/МnСO3 mixtures at 1200 °C which is less than their sintering temperature. The possibility to obtain LaSrMnO3 powders by solid state synthesis for smart coatings was shown.

Hydrothermally grown and self-assembled modified titanium and nickel oxide composite nanosheets on Nitinol-based fibers for efficient solid phase microextraction.

PubMed

Wang, Huiju; Song, Wenlan; Zhang, Min; Zhen, Qi; Guo, Mei; Zhang, Yida; Du, Xinzhen

2016-10-14

A novel titanium and nickel oxide composite nanosheets (TiO 2 /NiOCNSs) coating was in situ grown on a Nitinol (NiTi) wire by direct hydrothermal treatment and modified by self-assembly of trichlorophenylsilane for solid phase microextraction (SPME). TiO 2 /NiOCNSs were radially oriented and chemically bonded to the NiTi substrate with double-faced open access sites. Moreover the phenyl modified TiO 2 /NiOCNSs (TiO 2 /NiOCNSs-Ph) coating exhibited original surface supporting framework favorable for effective SPME. The extraction performance of TiO 2 /NiOCNSs-Ph coated NiTi (NiTi-TiO 2 /NiOCNSs-Ph) fiber was investigated for the concentration and detection of ultraviolet (UV) filters, polycyclic aromatic hydrocarbons (PAHs), phthalate acid esters and polychlorinated biphenyls coupled to HPLC with UV detection. The novel fiber exhibited better selectivity for UV filters and PAHs and presented greater extraction capability compared to commercial polydimethylsiloxane and polyacrylate fibers. Under the optimized conditions for SPME of UV filters, the proposed method presented linear ranges from 0.1 to 300μg/L with correlation coefficients of higher than 0.999 and limits of detection from 0.030μg/L to 0.064μg/L. Relative standard deviations (RSDs) were below 7.16% and 8.42% for intra-day and inter-day measurements with the single fiber, respectively. Furthermore RSDs for fiber-to-fiber reproducibility from 6.57% to 8.93% were achieved. The NiTi-TiO 2 /NiOCNSs-Ph fiber can be used up to 200 times. The proposed method was successfully applied to the preconcentration and determination of trace target UV filters in different environmental water samples. The relative recoveries from 87.3% to 104% were obtained with RSDs less than 8.7%. Copyright © 2016 Elsevier B.V. All rights reserved.

Solid-phase microextraction low temperature plasma mass spectrometry for the direct and rapid analysis of chemical warfare simulants in complex mixtures.

PubMed

Dumlao, Morphy C; Jeffress, Laura E; Gooding, J Justin; Donald, William A

2016-06-21

Solid-phase microextraction (SPME) is directly integrated with low temperature plasma ionisation mass spectrometry to rapidly detect organophosphate chemical warfare agent simulants and their hydrolysis products in chemical mixtures, including urine. In this sampling and ionization method, the fibre serves: (i) to extract molecules from their native environment, and (ii) as the ionization electrode that is used to desorb and ionize molecules directly from the SPME surface. By use of a custom fabricated SPME fibre consisting of a stainless steel needle coated with a Linde Type A (LTA) zeolitic microporous material and low temperature plasma mass spectrometry, protonated dimethyl methylphosphonate (DMMP), diethyl ethylphosphonate (DEEP) and pinacolyl methylphosphonic acid (PinMPA) can be detected at less than 100 ppb directly in water and urine. Organophosphates were not readily detected by this approach using an uncoated needle in negative control experiments. The use of the LTA coating significantly outperformed the use of a high alumina Zeolite Socony Mobil-5 (ZSM-5) coating of comparable thickness that is significantly less polar than LTA. By conditioning the LTA probe by immersion in an aqueous CuSO4 solution, the ion abundance for protonated DMMP increased by more than 300% compared to that obtained without any conditioning. Sample recovery values were between 96 and 100% for each analyte. The detection of chemical warfare agent analogues and hydrolysis products required less than 2 min per sample. A key advantage of this sampling and ionization method is that analyte ions can be directly and rapidly sampled from chemical mixtures, such as urine and seawater, without sample preparation or chromatography for sensitive detection by mass spectrometry. This ion source should prove beneficial for portable mass spectrometry applications because relatively low detection limits can be obtained without the use of compressed gases, fluid pumps, and lasers. Moreover, the ion source is compact, can be powered with a 10 V battery, and is tolerant of complex mixtures.

Simultaneous determination of traces of pyrethroids, organochlorines and other main plant protection agents in agricultural soils by headspace solid-phase microextraction-gas chromatography.

PubMed

Fernandez-Alvarez, Maria; Llompart, Maria; Lamas, J Pablo; Lores, Marta; Garcia-Jares, Carmen; Cela, Rafael; Dagnac, Thierry

2008-04-25

A solvent-free and simple method based on headspace solid-phase microextraction (HS-SPME) was developed in order to determine simultaneously 36 common pesticides and breakdown products (mostly pyrethroids and organochlorine compounds) in soil. The analysis was carried out by gas chromatography with micro-electron-capture detection (GC-microECD). As far as we know, this is the first study about the SPME of pyrethroid insecticides from soil. Factors such as extraction temperature, matrix modification by addition of water, salt addition (% NaCl) and fiber coating were considered in the optimization of the HS-SPME. To this end, a 3 x 2(3-1) fractional factorial design was performed. The results showed that temperature and fiber coating were the most significant variables affecting extraction efficiency. A suitable sensitivity for all investigated compounds was achieved at 100 degrees C by extracting soil samples wetted with 0.5 mL of ultrapure water (0% NaCl) employing a polyacrylate (PA) coating fiber. Using the recommended extraction conditions with GC-microECD, a linear calibration could be achieved over a range of two orders of magnitude for both groups of analytes. Limits of detection (LODS) at the sub-ng g(-1) level were attained and relative standard deviations (RSDs) were found to be lower than 14% for both groups of pesticides. Matrix effects were investigated by the analysis of different soil samples fortified with the target compounds. The method accuracy was assessed and good recovery values (>70%, in most cases) were obtained. The method was also validated with a certified reference material (RTC-CRM818-050), which was quantified using a standard addition protocol. Finally, the proposed HS-SPME-GC-microECD methodology was further applied to the screening of environmental soil samples for the presence of the target pesticides.

Fabrication of ciprofloxacin molecular imprinted polymer coating on a stainless steel wire as a selective solid-phase microextraction fiber for sensitive determination of fluoroquinolones in biological fluids and tablet formulation using HPLC-UV detection.

PubMed

Mirzajani, Roya; Kardani, Fatemeh

2016-04-15

A molecularly imprinted polymer (MIP) fiber on stainless steel wire using ciprofloxacin template with a mild template removal condition was synthetized and evaluated for fiber solid phase microextraction (SPME) of fluoroquinolones (FQs) from biological fluids and pharmaceutical samples, followed by high performance liquid chromatography analysis with UV detection (HPLC-UV). The developed MIP fiber exhibited high selectivity for the analytes in complex matrices. The coating of the fibers were inspected using fourier transform infrared spectrophotometry, thermogaravimetric analysis, energy dispersive X-ray (EDX) spectroscopy as well as by scanning electron microscopy (SEM). The fiber shows high thermal stability (up to 300°C), good reproducibility and long lifetime. The composite coating did not swell in organic solvents nor did it strip off from the substrate. It was also highly stable and extremely adherent to the surface of the stainless steel fiber. The fabricated fiber exclusively exhibited excellent extraction efficiency and selectivity for some FQs. The effective parameters influencing the microextraction efficiency such as pH, extraction time, desorption condition, and stirring rate were investigated. Under optimized conditions, the limits of detection of the four FQs ranged from 0.023-0.033 μg L(-1) (S/N=5) and the calibration graphs were linear in the concentration range from 0.1-40 μg L(-1), the inter-day and intraday relative standard deviations (RSD) for various FQs at three different concentration level (n=5) using a single fiber were 1.1-4.4% and the fiber to fiber RSD% (n=5) was 4.3-6.7% at 5 μg L(-1) of each anlyetes. The method was successfully applied for quantification of FQs in real samples including serum, plasma and tablet formulation with the recoveries between 97 to 102%. Copyright © 2016 Elsevier B.V. All rights reserved.

Nature and composition of fat bloom from palm kernel stearin and hydrogenated palm kernel stearin compound chocolates.

PubMed

Smith, Kevin W; Cain, Fred W; Talbot, Geoff

2004-08-25

Palm kernel stearin and hydrogenated palm kernel stearin can be used to prepare compound chocolate bars or coatings. The objective of this study was to characterize the chemical composition, polymorphism, and melting behavior of the bloom that develops on bars of compound chocolate prepared using these fats. Bars were stored for 1 year at 15, 20, or 25 degrees C. At 15 and 20 degrees C the bloom was enriched in cocoa butter triacylglycerols, with respect to the main fat phase, whereas at 25 degrees C the enrichment was with palm kernel triacylglycerols. The bloom consisted principally of solid fat and was sharper melting than was the fat in the chocolate. Polymorphic transitions from the initial beta' phase to the beta phase accompanied the formation of bloom at all temperatures.

Polymer Encapsulation of an Amorphous Pharmaceutical by initiated Chemical Vapor Deposition for Enhanced Stability

PubMed Central

2016-01-01

The usage of amorphous solids in practical applications, such as in medication, is commonly limited by the poor long-term stability of this state, because unwanted crystalline transitions occur. In this study, three different polymeric coatings are investigated for their ability to stabilize amorphous films of the model drug clotrimazole and to protect against thermally induced transitions. For this, drop cast films of clotrimazole are encapsulated by initiated chemical vapor deposition (iCVD), using perfluorodecyl acrylate (PFDA), hydroxyethyl methacrylate (HEMA), and methacrylic acid (MAA). The iCVD technique operates under solvent-free conditions at low temperatures, thus leaving the solid state of the encapsulated layer unaffected. Optical microscopy and X-ray diffraction data reveal that at ambient conditions of about 22 °C, any of these iCVD layers extends the lifetime of the amorphous state significantly. At higher temperatures (50 or 70 °C), the p-PFDA coating is unable to provide protection, while the p-HEMA and p-MAA strongly reduce the crystallization rate. Furthermore, p-HEMA and p-MAA selectively facilitate a preferential alignment of clotrimazole and, interestingly, even suppress crystallization upon a temporary, rapid temperature increase (3 °C/min, up to 150 °C). The results of this study demonstrate how a polymeric coating, synthesized directly on top of an amorphous phase, can act as a stabilizing agent against crystalline transitions, which makes this approach interesting for a variety of applications. PMID:27467099

Polymer Encapsulation of an Amorphous Pharmaceutical by initiated Chemical Vapor Deposition for Enhanced Stability.

PubMed

Christian, Paul; Ehmann, Heike M A; Coclite, Anna Maria; Werzer, Oliver

2016-08-24

The usage of amorphous solids in practical applications, such as in medication, is commonly limited by the poor long-term stability of this state, because unwanted crystalline transitions occur. In this study, three different polymeric coatings are investigated for their ability to stabilize amorphous films of the model drug clotrimazole and to protect against thermally induced transitions. For this, drop cast films of clotrimazole are encapsulated by initiated chemical vapor deposition (iCVD), using perfluorodecyl acrylate (PFDA), hydroxyethyl methacrylate (HEMA), and methacrylic acid (MAA). The iCVD technique operates under solvent-free conditions at low temperatures, thus leaving the solid state of the encapsulated layer unaffected. Optical microscopy and X-ray diffraction data reveal that at ambient conditions of about 22 °C, any of these iCVD layers extends the lifetime of the amorphous state significantly. At higher temperatures (50 or 70 °C), the p-PFDA coating is unable to provide protection, while the p-HEMA and p-MAA strongly reduce the crystallization rate. Furthermore, p-HEMA and p-MAA selectively facilitate a preferential alignment of clotrimazole and, interestingly, even suppress crystallization upon a temporary, rapid temperature increase (3 °C/min, up to 150 °C). The results of this study demonstrate how a polymeric coating, synthesized directly on top of an amorphous phase, can act as a stabilizing agent against crystalline transitions, which makes this approach interesting for a variety of applications.

Molecular transport and flow past hard and soft surfaces: computer simulation of model systems.

PubMed

Léonforte, F; Servantie, J; Pastorino, C; Müller, M

2011-05-11

The equilibrium and flow of polymer films and drops past a surface are characterized by the interface and surface tensions, viscosity, slip length and hydrodynamic boundary position. These parameters of the continuum description are extracted from molecular simulations of coarse-grained models. Hard, corrugated substrates are modelled by a Lennard-Jones solid while polymer brushes are studied as prototypes of soft, deformable surfaces. Four observations are discussed. (i) If the surface becomes strongly attractive or is coated with a brush, the Navier boundary condition fails to describe the effect of the surface independently of the strength and type of the flow. This failure stems from the formation of a boundary layer with an effective, higher viscosity. (ii) In the case of brush-coated surfaces, flow induces a cyclic, tumbling motion of the tethered chain molecules. Their collective motion gives rise to an inversion of the flow in the vicinity of the grafting surfaces and leads to strong, non-Gaussian fluctuations of the molecular orientations. The flow past a polymer brush cannot be described by Brinkman's equation. (iii) The hydrodynamic boundary condition is an important parameter for predicting the motion of polymer droplets on a surface under the influence of an external force. Their steady-state velocity is dictated by a balance between the power that is provided by the external force and the dissipation. If there is slippage at the liquid-solid interface, the friction at the solid-liquid interface and the viscous dissipation of the flow inside the drop will be the dominant dissipation mechanisms; dissipation at the three-phase contact line appears to be less important on a hard surface. (iv) On a soft, deformable substrate like a polymer brush, we observe a lifting-up of the three-phase contact line. Controlling the grafting density and the incompatibility between the brush and the polymer liquid we can independently tune the softness of the surface and the contact angle and thereby identify the parameters for maximizing the deformation at the three-phase contact.

Development of a novel mixed hemimicelles dispersive micro solid phase extraction using 1-hexadecyl-3-methylimidazolium bromide coated magnetic graphene for the separation and preconcentration of fluoxetine in different matrices before its determination by fiber optic linear array spectrophotometry and mode-mismatched thermal lens spectroscopy.

PubMed

Kazemi, Elahe; Haji Shabani, Ali Mohammad; Dadfarnia, Shayessteh; Abbasi, Amir; Rashidian Vaziri, Mohammad Reza; Behjat, Abbas

2016-01-28

This study aims at developing a novel, sensitive, fast, simple and convenient method for separation and preconcentration of trace amounts of fluoxetine before its spectrophotometric determination. The method is based on combination of magnetic mixed hemimicelles solid phase extraction and dispersive micro solid phase extraction using 1-hexadecyl-3-methylimidazolium bromide coated magnetic graphene as a sorbent. The magnetic graphene was synthesized by a simple coprecipitation method and characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The retained analyte was eluted using a 100 μL mixture of methanol/acetic acid (9:1) and converted into fluoxetine-β-cyclodextrin inclusion complex. The analyte was then quantified by fiber optic linear array spectrophotometry as well as mode-mismatched thermal lens spectroscopy (TLS). The factors affecting the separation, preconcentration and determination of fluoxetine were investigated and optimized. With a 50 mL sample and under optimized conditions using the spectrophotometry technique, the method exhibited a linear dynamic range of 0.4-60.0 μg L(-1), a detection limit of 0.21 μg L(-1), an enrichment factor of 167, and a relative standard deviation of 2.1% and 3.8% (n = 6) at 60 μg L(-1) level of fluoxetine for intra- and inter-day analyses, respectively. However, with thermal lens spectrometry and a sample volume of 10 mL, the method exhibited a linear dynamic range of 0.05-300 μg L(-1), a detection limit of 0.016 μg L(-1) and a relative standard deviation of 3.8% and 5.6% (n = 6) at 60 μg L(-1) level of fluoxetine for intra- and inter-day analyses, respectively. The method was successfully applied to determine fluoxetine in pharmaceutical formulation, human urine and environmental water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of a solid-phase microextraction gas chromatography with microelectron-capture detection method for the determination of 5-bromo-5-nitro-1,3-dioxane in rinse-off cosmetics.

PubMed

Fernandez-Alvarez, Maria; Lamas, J Pablo; Sanchez-Prado, Lucia; Llompart, Maria; Garcia-Jares, Carmen; Lores, Marta

2010-10-22

5-Bromo-5-nitro-1,3-dioxane (bronidox) is a bromine-containing preservative often used in rinse-off cosmetics but also subjected to several restrictions according to the European Cosmetic Products Regulation. Thus, as a part of a quality control procedure, analytical methods for the determination of this compound in different types of cosmetics are required. In the present work, a solvent-free and simple methodology based on solid-phase microextraction (SPME) followed by gas chromatography with microelectron capture detection (GC-μECD) has been developed and validated for the determination of bronidox in cosmetic samples such as shampoos, body cleansers or facial exfoliants. As far as we know, this is the first application of SPME to this preservative. Negative matrix effects due to the complexity of the studied samples were reduced by dilution with ultrapure water. The influence of several factors on the SPME procedure such as fiber coating, extraction temperature, salt addition (NaCl) and sampling mode has been assessed by performing a 2(4)-factorial design. After optimization, the recommended procedure was established as follows: direct solid-phase microextraction (DSPME), using a PDMS/DVB coating, of 10 mL of diluted cosmetic with 20% NaCl, at room temperature, under stirring for 30 min. Using these suggested extraction conditions, linear calibration could be achieved, with limits of detection (LOD) and quantification (LOQ) well below the maximum authorized concentration (0.1%) established by the European legislation. Relative standard deviations (RSD) lower than 10% were obtained for both within a day and among days precision. The method was applied to diverse types of formulations spiked with bronidox at different concentration levels (0.008-0.10%); these samples were quantified by external calibration and satisfactory recoveries (≥ 70%) were obtained in all cases. Finally, the SPME-GC-μECD methodology was applied to the analysis of several cosmetics labeled or not as containing bronidox. The presence of this preservative in some of these samples was confirmed by GC-MS. Copyright © 2010 Elsevier B.V. All rights reserved.

Parasitic oscillation suppression in solid state lasers using optical coatings

DOEpatents

Honea, Eric C.; Beach, Raymond J.

2005-06-07

A laser gain medium having a layered coating on at least certain surfaces of the laser gain medium. The layered coating having a reflective inner material and an absorptive scattering outside material.

The effect of packaging methods (paper, active paper, and edible coating) on the characteristic of papaya MJ9 in ambient temperature storage

NASA Astrophysics Data System (ADS)

Suwanti, D.; Utami, R.; Kawiji; Praseptiangga, D.; Khasanah, L. U.

2018-01-01

Papaya is one of the export commodities that contain high vitamin C but having short shelf-life. One method that use to extend the shelf-life and maintain the quality of papaya is packaging. The aim of this study was to investigate the effect of the packaging methods (paper, active paper and edible coating) on the characteristics of papaya MJ9 (weight loss, firmness, total soluble solid (TSS), Total Titratable Acid (TTA), pH, vitamin C and total mold and yeast). The packaging methods were control (F1), wrapping paper (F2), wrapping active paper (F3), combination of edible coating and wrapping paper (F4), and combination of edible coating and wrapping active paper (F5). The result showed that paper packaging, edible coating and active paper packaging significantly affected the weight loss, firmness, total soluble solid, total titratable acids, pH, vitamin C, and total mold and yeast of papaya. The weight loss, total soluble solid and pH of packaged papaya was lower than that of control sample, however, the value of firmness and total titratable acid was higher than that of the control sample. Packaging can inhibit the increase of weight loss, total soluble solids and pH, and the decrease of firmness, total titratable acid, vitamin C and total mold and yeast. Based on the papaya characteristics, the selected packaging method was the combination of edible coating and wrapping active paper.

Validation of an SPME method, using PDMS, PA, PDMS-DVB, and CW-DVB SPME fiber coatings, for analysis of organophosphorus insecticides in natural waters.

PubMed

Lambropoulou, D A; Sakkas, V A; Albanis, T A

2002-11-01

Solid-phase microextraction (SPME) has been optimized and applied to the determination of the organophosphorus insecticides diazinon, dichlofenthion, parathion methyl, malathion, fenitrothion, fenthion, parathion ethyl, bromophos methyl, bromophos ethyl, and ethion in natural waters. Four types of SPME fiber coated with different stationary phases (PDMS, PA, PDMS-DVB, and CW-DVB) were used to examine their extraction efficiencies for the compounds tested. Conditions that might affect the SPME procedure, such as extraction time and salt content, were investigated to determine the analytical performance of these fiber coatings for organophosphorus insecticides. The optimized procedure was applied to natural waters - tap, sea, river, and lake water - spiked in the concentration range 0.5 to 50 micro g L(-1) to obtain the analytical characteristics. Recoveries were relatively high - >80% for all types of aqueous sample matrix - and the calibration plots were reproducible and linear (R(2)>0.982) for all analytes with all the fibers tested. The limits of detection ranged from 2 to 90 ng L(-1), depending on the detector and the compound investigated, with relative standard deviations in the range 3-15% at all the concentration levels tested. The SPME partition coefficients (K(f)) of the organophosphorus insecticides were calculated experimentally for all the polymer coatings. The effect of organic matter such as humic acids on extraction efficiency was also studied. The analytical performance of the SPME procedure using all the fibers in the tested natural waters proved effective for the compounds.

New Mechanism of Extractive Electrospray Ionization Mass Spectrometry for Heterogeneous Solid Particles.

PubMed

Kumbhani, S; Longin, T; Wingen, L M; Kidd, C; Perraud, V; Finlayson-Pitts, B J

2018-02-06

Real-time in situ mass spectrometry analysis of airborne particles is important in several applications, including exposure studies in ambient air, industrial settings, and assessing impacts on visibility and climate. However, obtaining molecular and 3D structural information is more challenging, especially for heterogeneous solid or semisolid particles. We report a study of extractive electrospray ionization mass spectrometry (EESI-MS) for the analysis of solid particles with an organic coating. The goal is to elucidate how much of the overall particle content is sampled, and determine the sensitivity of this technique to the surface layers. It is shown that, for NaNO 3 particles coated with glutaric acid (GA), very little of the solid NaNO 3 core is sampled compared to the GA coating, whereas for GA particles coated with malonic acid (MA), significant signals from both the MA coating and the GA core are observed. However, conventional ESI-MS of the same samples collected on a Teflon filter (and then extracted) detects much more core material compared to EESI-MS in both cases. These results show that, for the experimental conditions used here, EESI-MS does not sample the entire particle but, instead, is more sensitive to surface layers. Separate experiments on single-component particles of NaNO 3 , GA, or citric acid show that there must be a kinetics limitation to dissolution that is important in determining EESI-MS sensitivity. We propose a new mechanism of EESI solvent droplet interaction with solid particles that is consistent with the experimental observations. In conjunction with previous EESI-MS studies of organic particles, these results suggest that EESI does not necessarily sample the entire particle when solid, and that not only solubility but also surface energies and the kinetics of dissolution play an important role.

Chemical and thermal stability of core-shelled magnetite nanoparticles and solid silica

NASA Astrophysics Data System (ADS)

Cendrowski, Krzysztof; Sikora, Pawel; Zielinska, Beata; Horszczaruk, Elzbieta; Mijowska, Ewa

2017-06-01

Pristine nanoparticles of magnetite were coated by solid silica shell forming core/shell structure. 20 nm thick silica coating significantly enhanced the chemical and thermal stability of the iron oxide. Chemical and thermal stability of this structure has been compared to the magnetite coated by mesoporous shell and pristine magnetite nanoparticles. It is assumed that six-membered silica rings in a solid silica shell limit the rate of oxygen diffusion during thermal treatment in air and prevent the access of HCl molecules to the core during chemical etching. Therefore, the core/shell structure with a solid shell requires a longer time to induce the oxidation of iron oxide to a higher oxidation state and, basically, even strong concentrated acid such as HCl is not able to dissolve it totally in one month. This leads to the desired performance of the material in potential applications such as catalysis and environmental protection.

Arsenic repartitioning during biogenic sulfidization and transformation of ferrihydrite

NASA Astrophysics Data System (ADS)

Kocar, Benjamin D.; Borch, Thomas; Fendorf, Scott

2010-02-01

Iron (hydr)oxides are strong sorbents of arsenic (As) that undergo reductive dissolution and transformation upon reaction with dissolved sulfide. Here we examine the transformation and dissolution of As-bearing ferrihydrite and subsequent As repartitioning amongst secondary phases during biotic sulfate reduction. Columns initially containing As(V)-ferrihydrite coated sand, inoculated with the sulfate reducing bacteria Desulfovibrio vulgaris (Hildenborough), were eluted with artificial groundwater containing sulfate and lactate. Rapid and consistent sulfate reduction coupled with lactate oxidation is observed at low As(V) loading (10% of the adsorption maximum). The dominant Fe solid phase transformation products at low As loading include amorphous FeS within the zone of sulfate reduction (near the inlet of the column) and magnetite downstream where Fe(II) (aq) concentrations increase; As is displaced from the zone of sulfidogenesis and Fe(III) (s) depletion. At high As(V) loading (50% of the adsorption maximum), sulfate reduction and lactate oxidation are initially slow but gradually increase over time, and all As(V) is reduced to As(III) by the end of experimentation. With the higher As loading, green rust(s), as opposed to magnetite, is a dominant Fe solid phase product. Independent of loading, As is strongly associated with magnetite and residual ferrihydrite, while being excluded from green rust and iron sulfide. Our observations illustrate that sulfidogenesis occurring in proximity with Fe (hydr)oxides induce Fe solid phase transformation and changes in As partitioning; formation of As sulfide minerals, in particular, is inhibited by reactive Fe(III) or Fe(II) either through sulfide oxidation or complexation.

Arsenic Repartitioning during Biogenic Sulfidization and Transformation of Ferrihydrite

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

Kocar, B.; Borch, T; Fendorf, S

Iron (hydr)oxides are strong sorbents of arsenic (As) that undergo reductive dissolution and transformation upon reaction with dissolved sulfide. Here we examine the transformation and dissolution of As-bearing ferrihydrite and subsequent As repartitioning amongst secondary phases during biotic sulfate reduction. Columns initially containing As(V)-ferrihydrite coated sand, inoculated with the sulfate reducing bacteria Desulfovibrio vulgaris (Hildenborough), were eluted with artificial groundwater containing sulfate and lactate. Rapid and consistent sulfate reduction coupled with lactate oxidation is observed at low As(V) loading (10% of the adsorption maximum). The dominant Fe solid phase transformation products at low As loading include amorphous FeS within themore » zone of sulfate reduction (near the inlet of the column) and magnetite downstream where Fe(II){sub (aq)} concentrations increase; As is displaced from the zone of sulfidogenesis and Fe(III){sub (s)} depletion. At high As(V) loading (50% of the adsorption maximum), sulfate reduction and lactate oxidation are initially slow but gradually increase over time, and all As(V) is reduced to As(III) by the end of experimentation. With the higher As loading, green rust(s), as opposed to magnetite, is a dominant Fe solid phase product. Independent of loading, As is strongly associated with magnetite and residual ferrihydrite, while being excluded from green rust and iron sulfide. Our observations illustrate that sulfidogenesis occurring in proximity with Fe (hydr)oxides induce Fe solid phase transformation and changes in As partitioning; formation of As sulfide minerals, in particular, is inhibited by reactive Fe(III) or Fe(II) either through sulfide oxidation or complexation.« less

Arsenic repartitioning during biogenic sulfidization and transformation of ferrihydrite

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

Kocar, Benjamin D.; Borch, Thomas; Fendorf, Scott

Iron (hydr)oxides are strong sorbents of arsenic (As) that undergo reductive dissolution and transformation upon reaction with dissolved sulfide. Here we examine the transformation and dissolution of As-bearing ferrihydrite and subsequent As repartitioning amongst secondary phases during biotic sulfate reduction. Columns initially containing As(V)-ferrihydrite coated sand, inoculated with the sulfate reducing bacteria Desulfovibrio vulgaris (Hildenborough), were eluted with artificial groundwater containing sulfate and lactate. Rapid and consistent sulfate reduction coupled with lactate oxidation is observed at low As(V) loading (10% of the adsorption maximum). The dominant Fe solid phase transformation products at low As loading include amorphous FeS within themore » zone of sulfate reduction (near the inlet of the column) and magnetite downstream where Fe(II)(aq) concentrations increase; As is displaced from the zone of sulfidogenesis and Fe(III)(s) depletion. At high As(V) loading (50% of the adsorption maximum), sulfate reduction and lactate oxidation are initially slow but gradually increase over time, and all As(V) is reduced to As(III) by the end of experimentation. With the higher As loading, green rust(s), as opposed to magnetite, is a dominant Fe solid phase product. Independent of loading, As is strongly associated with magnetite and residual ferrihydrite, while being excluded from green rust and iron sulfide. Our observations illustrate that sulfidogenesis occurring in proximity with Fe (hydr)oxides induce Fe solid phase transformation and changes in As partitioning; formation of As sulfide minerals, in particular, is inhibited by reactive Fe(III) or Fe(II) either through sulfide oxidation or complexation.« less

Bio-based coatings as potential barriers to chemical contaminants from recycled paper and board for food packaging.

PubMed

Guazzotti, V; Marti, A; Piergiovanni, L; Limbo, S

2014-01-01

Partition and diffusion experiments were carried out with paper and board samples coated with different biopolymers. The aim was to evaluate the physicochemical behaviour and barrier properties of bio-coatings against migration of typical contaminants from recycled paper packaging. Focus was directed towards water-based, renewable biopolymers, such as modified starches (cationic starch and cationic waxy starch), plant and animal proteins (gluten and gelatine), poured onto paper with an automatic applicator. Additionally, a comparison with polyethylene-laminated paper was performed. Microstructural observations of the bio-coated paper allowed the characterisation of samples. From the partitioning studies, considerable differences in the adsorption behaviour of the selected contaminants between bio-coated or uncoated paper and air were highlighted. For both the polar and non-polar compounds considered (benzophenone and diisobutyl phthalate, respectively), the lowest values of partition coefficients were found when paper was bio-coated, making it evident that biopolymers acted as chemical/physical barriers towards these contaminants. These findings are discussed considering the characteristics of the tested biopolymers. Diffusion studies into the solid food simulant poly 2,6-diphenyl-p-phenylene oxide, also known as Tenax(®), confirmed that all the tested biopolymers slowed down migration. The Weibull kinetic model was fitted to the experimental data to compare migration from paper and bio-coated paper. Values found for β, an index determining the pattern of curvature, ranged from 1.1 to 1.7 for uncoated and polyethylene paper, whereas for bio-coated papers they ranged from 2.2 to 4.9, corresponding to the presence of an evident lag phase due to barrier properties of the tested bio-coatings.

Air sampling with solid phase microextraction

NASA Astrophysics Data System (ADS)

Martos, Perry Anthony

There is an increasing need for simple yet accurate air sampling methods. The acceptance of new air sampling methods requires compatibility with conventional chromatographic equipment, and the new methods have to be environmentally friendly, simple to use, yet with equal, or better, detection limits, accuracy and precision than standard methods. Solid phase microextraction (SPME) satisfies the conditions for new air sampling methods. Analyte detection limits, accuracy and precision of analysis with SPME are typically better than with any conventional air sampling methods. Yet, air sampling with SPME requires no pumps, solvents, is re-usable, extremely simple to use, is completely compatible with current chromatographic equipment, and requires a small capital investment. The first SPME fiber coating used in this study was poly(dimethylsiloxane) (PDMS), a hydrophobic liquid film, to sample a large range of airborne hydrocarbons such as benzene and octane. Quantification without an external calibration procedure is possible with this coating. Well understood are the physical and chemical properties of this coating, which are quite similar to those of the siloxane stationary phase used in capillary columns. The log of analyte distribution coefficients for PDMS are linearly related to chromatographic retention indices and to the inverse of temperature. Therefore, the actual chromatogram from the analysis of the PDMS air sampler will yield the calibration parameters which are used to quantify unknown airborne analyte concentrations (ppb v to ppm v range). The second fiber coating used in this study was PDMS/divinyl benzene (PDMS/DVB) onto which o-(2,3,4,5,6- pentafluorobenzyl) hydroxylamine (PFBHA) was adsorbed for the on-fiber derivatization of gaseous formaldehyde (ppb v range), with and without external calibration. The oxime formed from the reaction can be detected with conventional gas chromatographic detectors. Typical grab sampling times were as small as 5 seconds. With 300 seconds sampling, the formaldehyde detection limit was 2.1 ppbv, better than any other 5 minute sampling device for formaldehyde. The first-order rate constant for product formation was used to quantify formaldehyde concentrations without a calibration curve. This spot sampler was used to sample the headspace of hair gel, particle board, plant material and coffee grounds for formaldehyde, and other carbonyl compounds, with extremely promising results. The SPME sampling devices were also used for time- weighted average sampling (30 minutes to 16 hours). Finally, the four new SPME air sampling methods were field tested with side-by-side comparisons to standard air sampling methods, showing a tremendous use of SPME as an air sampler.

Galvanic Liquid Applied Coating Development for Protection of Steel in Concrete

NASA Technical Reports Server (NTRS)

Curran, Joseph John; Curran, Jerry; MacDowell, Louis

2004-01-01

Corrosion of reinforcing steel in concrete is a major problem affecting NASA facilities at Kennedy Space Center (KSC), other government agencies, and the general public. Problems include damage to KSC launch support structures, transportation and marine infrastructures, as well as building structures. A galvanic liquid applied coating was developed at KSC in order to address this problem. The coating is a non-epoxy metal rich ethyl silicate liquid coating. The coating is applied as a liquid from initial stage to final stage. Preliminary data shows that this coating system exceeds the NACE 100 millivolt shift criterion. The remainder of the paper details the development of the coating system through the following phases: Phase I: Development of multiple formulations of the coating to achieve easy application characteristics, predictable galvanic activity, long-term protection, and minimum environmental impact. Phase II: Improvement of the formulations tested in Phase I including optimization of metallic loading as well as incorporation of humectants for continuous activation. Phase III: Application and testing of improved formulations on the test blocks. Phase IV: Incorporation of the final formulation upgrades onto large instrumented structures (slabs).

40 CFR 60.461 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... in subpart A of this part. Coating means any organic material that is applied to the surface of metal... operation means the application system used to apply an organic coating to the surface of any continuous... of coating solids, of volatile organic compounds (VOC's) in a coating. (b) All symbols used in this...

40 CFR 60.461 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... in subpart A of this part. Coating means any organic material that is applied to the surface of metal... operation means the application system used to apply an organic coating to the surface of any continuous... of coating solids, of volatile organic compounds (VOC's) in a coating. (b) All symbols used in this...

40 CFR 60.461 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... in subpart A of this part. Coating means any organic material that is applied to the surface of metal... operation means the application system used to apply an organic coating to the surface of any continuous... of coating solids, of volatile organic compounds (VOC's) in a coating. (b) All symbols used in this...

40 CFR 60.461 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... in subpart A of this part. Coating means any organic material that is applied to the surface of metal... operation means the application system used to apply an organic coating to the surface of any continuous... of coating solids, of volatile organic compounds (VOC's) in a coating. (b) All symbols used in this...

Commercialization of NASA PS304 Solid Lubricant Coating Enhanced by Fundamental Powder Flow Research

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.

2003-01-01

The NASA Glenn Research Center has developed a patented high-temperature solid lubricant coating, designated PS304, for reducing friction and wear in bearing systems. The material used to produce the coating is initially a blend of metallic and ceramic powders that are deposited on the bearing surface by the plasma spray process. PS304 was developed to lubricate foil air bearings in Oil-Free turbomachinery, where the moving surfaces are coated with a hydrodynamic air film except at the beginning and end of an operation cycle when the air film is not present. The coating has been successful in several applications including turbochargers, land-based turbines, and industrial drying furnace conveyor components, with current development activities directed at implementation in Oil-Free aeropropulsion engines.

A Review of Tribological Coatings for Control Drive Mechanisms in Space Reactors

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

CJ Larkin; JD Edington; BJ Close

2006-02-21

Tribological coatings must provide lubrication for moving components of the control drive mechanism for a space reactor and prevent seizing due to friction or diffusion welding to provide highly reliable and precise control of reflector position over the mission lifetime. Several coatings were evaluated based on tribological performance at elevated temperatures and in ultrahigh vacuum environments. Candidates with proven performance in the anticipated environment are limited primarily to disulfide materials. Irradiation data for these coatings is nonexistent. Compatibility issues between coating materials and structural components may require the use of barrier layers between the solid lubricant and structural components tomore » prevent deleterious interactions. It would be advisable to consider possible lubricant interactions prior to down-selection of structural materials. A battery of tests was proposed to provide the necessary data for eventual solid lubricant/coating selection.« less

Zirconia coating stabilized super-iron alkaline cathodes

NASA Astrophysics Data System (ADS)

Yu, Xingwen; Licht, Stuart

A low-level zirconia coating significantly stabilizes high energy alkaline super-iron cathodes, and improves the energy storage capacity of super-iron batteries. Zirconia coating is derived from ZrCl 4 in an organic medium through the conversion of ZrCl 4 to ZrO 2. In alkaline battery system, ZrO 2 provides an intact shield for the cathode materials and the hydroxide shuttle through the coating sustains alkaline cathode redox chemistry. Most super-iron cathodes are solid-state stable, such as K 2FeO 4 and Cs 2FeO 4, but tend to be passivated in alkaline electrolyte due to the formation of Fe(III) over layer. Zirconia coating effectively enhances the stability of these super-iron cathodes. However, for solid-state unstable super-iron cathode (e.g. BaFeO 4), only a little stabilization effect of zirconia coating is observed.

Phase constitution characteristics of the Fe-Al alloy layer in the HAZ of calorized steel pipe

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

Li Yajiang; Zou Zengda; Wei Xing

1997-09-01

Mechanical properties of the welding region and phase constitution characteristics in the iron-aluminum (Fe-Al) alloy layer of calorized steel pipes were researched by means of metallography, which included the use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron probe microanalysis (EPMA) and an X-ray diffractometer. Experimental results indicated that the Fe-Al alloy layer of calorized steel pipe was mainly composed of an FeAl phase, an Fe{sub 3}Al phase and an {alpha}-Fe(Al) solid solution, and the microhardness in the Fe-Al coating was 600--310 HM from the surface layer to the inside. There were no higher aluminum content phases, suchmore » as brittle FeAl{sub 2}, Fe{sub 2}Al{sub 5} and FeAl{sub 3}. By controlling the aluminizing process parameters, the ability to bear deformation and weld-ability of the calorized steel pipe were remarkably improved.« less

Influence of frequency on the structure of zirconium oxide coatings deposited from aqueous electrolytes under microplasma oxidation

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

Gubaidulina, Tatiana A., E-mail: goub2002@mail.ru; Sergeev, Viktor P., E-mail: vserg@mail.tomsknet.ru; Fedorischeva, Marina V., E-mail: fmw@ispms.tsc.ru

2015-10-27

The work describes the microplasma oxidation (MPO) of zirconium surface resulting in the formation of zirconium oxide Zr-Al-Nb-O. We have used novel power supply to deposit oxide ceramic coatings by MPO and studied the effect of current density on the phase structure of oxide ceramic coatings. The size of microcracks in the coatings was determined at different frequencies. We have also used EVO50c scanning election microscope with an attachment for elemental analysis to study the morphology and elemental composition of oxide ceramic coating. In addition, we have established the influence of the frequency on the phase composition of the coating:more » at the frequency of 2500 Hz, the fraction of monoclinic phase was 18%, while the fraction of tetragonal phase amounted to 72%. The oxide ceramic coating produced at 250 Hz contained 38% of monoclinic phase and 62% of tetragonal phase; in addition, it had no buildups and craters.« less

Aging Wire Insulation Assessment by Phase Spectrum Examination of Ultrasonic Guided Waves

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Madaras, Eric I.

2003-01-01

Wire integrity has become an area of concern to the aerospace community including DoD, NASA, FAA, and Industry. Over time and changing environmental conditions, wire insulation can become brittle and crack. The cracks expose the wire conductor and can be a source of equipment failure, short circuits, smoke, and fire. The technique of using the ultrasonic phase spectrum to extract material properties of the insulation is being examined. Ultrasonic guided waves will propagate in both the wire conductor and insulation. Assuming the condition of the conductor remains constant then the stiffness of the insulator can be determined by measuring the ultrasonic guided wave velocity. In the phase spectrum method the guided wave velocity is obtained by transforming the time base waveform to the frequency domain and taking the phase difference between two waveforms. The result can then be correlated with a database, derived by numerical model calculations, to extract material properties of the wire insulator. Initial laboratory tests were performed on a simple model consisting of a solid cylinder and then a solid cylinder with a polymer coating. For each sample the flexural mode waveform was identified. That waveform was then transformed to the frequency domain and a phase spectrum was calculated from a pair of waveforms. Experimental results on the simple model compared well to numerical calculations. Further tests were conducted on aircraft or mil-spec wire samples, to see if changes in wire insulation stiffness can be extracted using the phase spectrum technique.

Method of making sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells

DOEpatents

Isenberg, Arnold O.

1989-01-01

An electrochemical apparatus is made containing an exterior electorde bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

Sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells

DOEpatents

Isenberg, Arnold O.

1987-01-01

An electrochemical apparatus is made containing an exterior electrode bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

Encapsulation of thermal energy storage media

DOEpatents

Dhau, Jaspreet; Goswami, Dharendra; Jotshi, Chand K.; Stefanakos, Elias K.

2017-09-19

In one embodiment, a phase change material is encapsulated by forming a phase change material pellet, coating the pellet with flexible material, heating the coated pellet to melt the phase change material, wherein the phase change materials expands and air within the pellet diffuses out through the flexible material, and cooling the coated pellet to solidify the phase change material.

Process to produce lithium-polymer batteries

DOEpatents

MacFadden, Kenneth Orville

1998-01-01

A polymer bonded sheet product suitable for use as an electrode in a non-aqueous battery system. A porous electrode sheet is impregnated with a solid polymer electrolyte, so as to diffuse into the pores of the electrode. The composite is allowed to cool, and the electrolyte is entrapped in the porous electrode. The sheet products composed have the solid polymer electrolyte composition diffused into the active electrode material by melt-application of the solid polymer electrolyte composition into the porous electrode material sheet. The solid polymer electrolyte is maintained at a temperature that allows for rapid diffusion into the pores of the electrode. The composite electrolyte-electrode sheets are formed on current collectors and can be coated with solid polymer electrolyte prior to battery assembly. The interface between the solid polymer electrolyte composite electrodes and the solid polymer electrolyte coating has low resistance.

High temperature oxidation behavior of interconnect coated with LSCF and LSM for solid oxide fuel cell by screen printing

NASA Astrophysics Data System (ADS)

Lee, Shyong; Chu, Chun-Lin; Tsai, Ming-Jui; Lee, Jye

2010-01-01

The current study examined the effect of La 0.6Sr 0.4Co 0.2Fe 0.8O 3 (LSCF) and La 0.7Sr 0.3MnO 3 (LSM) coatings on the electrical properties and oxidation resistance of Crofer22 APU at 800 °C hot air. LSCF and LSM were coated on Crofer22 APU by screen printing and sintered over temperatures ranging from 1000 to 1100 °C in N 2. The coated alloy was first checked for compositions, morphology and interface conditions and then treated in a simulated oxidizing environment at 800 °C for 200 h. After measuring the long-term electrical resistance, the area specific resistance (ASR) at 800 °C for the alloy coated with LSCF was less than its counterpart coated with LSM. This work used LSCF coating as a metallic interconnect to reduce working temperature for the solid oxide fuel cell.

Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

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

Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a uniquemore » opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained beta-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer brushes, or the most effective molecular release kinetics for drug delivery applications, for example.« less

Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

NASA Astrophysics Data System (ADS)

Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

2016-10-01

Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a unique opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained β-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer brushes, or the most effective molecular release kinetics for drug delivery applications, for example.

Quantitative spatial distribution of sirolimus and polymers in drug-eluting stents using confocal Raman microscopy.

PubMed

Balss, K M; Llanos, G; Papandreou, G; Maryanoff, C A

2008-04-01

Raman spectroscopy was used to differentiate each component found in the CYPHER Sirolimus-eluting Coronary Stent. The unique spectral features identified for each component were then used to develop three separate calibration curves to describe the solid phase distribution found on drug-polymer coated stents. The calibration curves were obtained by analyzing confocal Raman spectral depth profiles from a set of 16 unique formulations of drug-polymer coatings sprayed onto stents and planar substrates. The sirolimus model was linear from 0 to 100 wt % of drug. The individual polymer calibration curves for poly(ethylene-co-vinyl acetate) [PEVA] and poly(n-butyl methacrylate) [PBMA] were also linear from 0 to 100 wt %. The calibration curves were tested on three independent drug-polymer coated stents. The sirolimus calibration predicted the drug content within 1 wt % of the laboratory assay value. The polymer calibrations predicted the content within 7 wt % of the formulation solution content. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra from five formulations confirmed a linear response to changes in sirolimus and polymer content. Copyright 2007 Wiley Periodicals, Inc.

Quantification of furanic compounds in coated deep-fried products simulating normal preparation and consumption: optimisation of HS-SPME analytical conditions by response surface methodology.

PubMed

Pérez-Palacios, T; Petisca, C; Melo, A; Ferreira, I M P L V O

2012-12-01

The validation of a method for the simultaneous quantification of furanic compounds in coated deep-fried samples processed and handled as usually consumed is presented. The deep-fried food was grinded using a device that simulates the mastication, and immediately analysed by headspace solid phase microextraction coupled to gas chromatography-mass spectrometry. Parameters affecting the efficiency of HS-SPME procedure were selected by response surface methodology, using a 2(3) full-factorial central composite design. Optimal conditions were achieved using 2g of sample, 3g of NaCl and 40min of absorption time at 37°C. Consistency between predicted and experimented values was observed and quality parameters of the method were established. As a result, furan, 2-furfural, furfuryl alcohol and 2-pentylfuran were, for the first time, simultaneously detected and quantified (5.59, 0.27, 10.48 and 1.77μgg(-1) sample, respectively) in coated deep-fried fish, contributing to a better understanding of the amounts of these compounds in food. Copyright © 2012 Elsevier Ltd. All rights reserved.

Vapors and Droplets Mixture Deposition of Metallic Coatings by Very Low Pressure Plasma Spraying

NASA Astrophysics Data System (ADS)

Vautherin, B.; Planche, M.-P.; Bolot, R.; Quet, A.; Bianchi, L.; Montavon, G.

2014-04-01

In recent years, the very low pressure plasma-spraying (VLPPS) process has been intensely developed and implemented to manufacture thin, dense and finely structured ceramic coatings for various applications, such as Y2O3 for diffusion barriers, among other examples. This paper aims at presenting developments carried out on metallic coatings. Aluminum was chosen as a demonstrative material due to its "moderate" vaporization enthalpy (i.e., 38.23 KJ cm-3) compared to the one of copper (i.e., 55.33 KJ cm-3), cobalt (i.e., 75.03 KJ cm-3), or even tantalum (i.e., 87.18 KJ cm-3). The objective of this work is primarily to better understand the behavior of a solid precursor injected into the plasma jet leading to the formation of vapors and to better control the factors affecting the coating structure. Nearly dense aluminum coatings were successfully deposited by VLPPS at 100 Pa with an intermediate power plasma torch (i.e., Sulzer Metco F4 type gun with maximum power of 45 kW). Optical emission spectroscopy (OES) was implemented to study and analyze the vapor behavior into the plasma jet. Simplified CFD modeling allowed better understanding of some of the thermo-physical mechanisms. The effect of powder-size distribution, substrate temperature and spray distance were studied. The phase composition and microstructural features of the coatings were characterized by XRD and SEM. Moreover, Vickers microhardness measurements were implemented.

Alendronate Sodium as Enteric Coated Solid Lipid Nanoparticles; Preparation, Optimization, and In Vivo Evaluation to Enhance Its Oral Bioavailability.

PubMed

Hosny, Khaled Mohamed

2016-01-01

Treatment of osteoporosis with alendronate sodium has several challenges. The first challenge is the low bioavailability. The second main challenge is side effects, which include oesophageal ulceration. The aim of this research was to reformulate alendronate sodium as enteric coated solid lipid nanoparticles in order to enhance its bioavailability, and preventing the free alendronate sodium from coming into direct contact with the gastrointestinal mucosa, and thereby reducing the possibility of side effects. Enteric coated solid lipid nanoparticles were prepared according to the Box-Behnken design employing Design expert® software, and characterized for size, morphology, and entrapment efficiency. The optimized formula was coated with an Eudragit S100 and evaluated for drug release in acidic and basic media, stability studies and pharmacokinetic evaluations on rabbits. The results indicated that, using Derringer's desirability functional tool for optimization, the highest entrapment efficiency value of 74.3% and the smallest size value of 98 nm were predicted under optimum conditions with a desirability value of 0.917. The optimized nanoparticles released alendronate sodium only at an alkaline pH. The pharmacokinetic evaluation revealed that alendronate sodium bioavailability was enhanced by more than 7.4-fold in rabbits. In conclusion, enteric coated solid lipid nanoparticles is a promising formula for the delivery of alendronate sodium, eliminating its oesophageal side effects and enhancing its bioavailability.

Alendronate Sodium as Enteric Coated Solid Lipid Nanoparticles; Preparation, Optimization, and In Vivo Evaluation to Enhance Its Oral Bioavailability

PubMed Central

Hosny, Khaled Mohamed

2016-01-01

Treatment of osteoporosis with alendronate sodium has several challenges. The first challenge is the low bioavailability. The second main challenge is side effects, which include oesophageal ulceration. The aim of this research was to reformulate alendronate sodium as enteric coated solid lipid nanoparticles in order to enhance its bioavailability, and preventing the free alendronate sodium from coming into direct contact with the gastrointestinal mucosa, and thereby reducing the possibility of side effects. Enteric coated solid lipid nanoparticles were prepared according to the Box-Behnken design employing Design expert® software, and characterized for size, morphology, and entrapment efficiency. The optimized formula was coated with an Eudragit S100 and evaluated for drug release in acidic and basic media, stability studies and pharmacokinetic evaluations on rabbits. The results indicated that, using Derringer's desirability functional tool for optimization, the highest entrapment efficiency value of 74.3% and the smallest size value of 98 nm were predicted under optimum conditions with a desirability value of 0.917. The optimized nanoparticles released alendronate sodium only at an alkaline pH. The pharmacokinetic evaluation revealed that alendronate sodium bioavailability was enhanced by more than 7.4-fold in rabbits. In conclusion, enteric coated solid lipid nanoparticles is a promising formula for the delivery of alendronate sodium, eliminating its oesophageal side effects and enhancing its bioavailability. PMID:27148747

Ionic-liquid-mediated poly(dimethylsiloxane)- grafted carbon nanotube fiber prepared by the sol-gel technique for the head space solid-phase microextraction of methyl tert-butyl ether using GC.

PubMed

Vatani, Hossein; Yazdi, Ali Sarafraz

2014-01-01

A headspace solid-phase microextraction method was developed for the preconcentration and extraction of methyl tert-butyl ether. An ionic-liquid-mediated multiwalled carbon nanotube-poly(dimethylsiloxane) hybrid coating, which was prepared by covalent functionalization of multiwalled carbon nanotubes with hydroxyl-terminated poly(dimethylsiloxane) using the sol-gel technique, was used as solid-phase microextraction adsorbent. This innovative fiber exhibited a highly porous surface structure, high thermal stability (at least 320°C) and long lifespan (over 210 uses). Potential factors affecting the extraction efficiency were optimized. Under the optimum conditions, the method LOD (S/N = 3) was 0.007 ng/mL and the LOQ (S/N = 10) was 0.03 ng/mL. The calibration curve was linear in the range of 0.03-200 ng/mL. The RSDs for one fiber (repeatability, n = 5) at three different concentrations (0.05, 1, and 150 ng/mL) were 5.1, 4.2, and 4.6% and for the fibers obtained from different batches (reproducibility, n = 3) were 6.5, 5.9, and 6.3%, respectively. The developed method was successfully applied to the determination of methyl tert-butyl ether in different real water samples on three consecutive days. The relative recoveries for the spiked samples with 0.05, 1, and 150 ng/mL were between 94-104%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determining octanol-water partition coefficients for extremely hydrophobic chemicals by combining "slow stirring" and solid-phase microextraction.

PubMed

Jonker, Michiel T O

2016-06-01

Octanol-water partition coefficients (KOW ) are widely used in fate and effects modeling of chemicals. Still, high-quality experimental KOW data are scarce, in particular for very hydrophobic chemicals. This hampers reliable assessments of several fate and effect parameters and the development and validation of new models. One reason for the limited availability of experimental values may relate to the challenging nature of KOW measurements. In the present study, KOW values for 13 polycyclic aromatic hydrocarbons were determined with the gold standard "slow-stirring" method (log KOW 4.6-7.2). These values were then used as reference data for the development of an alternative method for measuring KOW . This approach combined slow stirring and equilibrium sampling of the extremely low aqueous concentrations with polydimethylsiloxane-coated solid-phase microextraction fibers, applying experimentally determined fiber-water partition coefficients. It resulted in KOW values matching the slow-stirring data very well. Therefore, the method was subsequently applied to a series of 17 moderately to extremely hydrophobic petrochemical compounds. The obtained KOW values spanned almost 6 orders of magnitude, with the highest value measuring 10(10.6) . The present study demonstrates that the hydrophobicity domain within which experimental KOW measurements are possible can be extended with the help of solid-phase microextraction and that experimentally determined KOW values can exceed the proposed upper limit of 10(9) . Environ Toxicol Chem 2016;35:1371-1377. © 2015 SETAC. © 2015 SETAC.

Solid-phase microextraction followed by gas chromatography-mass spectrometry for the determination of ink photo-initiators in packed milk.

PubMed

Negreira, N; Rodríguez, I; Rubí, E; Cela, R

2010-06-30

A novel, single step method for the determination of seven ink photo-initiators in carton packed milk samples is described. Solid-phase microextraction (SPME) and gas chromatography (GC), combined with mass spectrometry (MS), were used as sample preparation and determination techniques, respectively. Parameters affecting the performance of the microextraction process were thoroughly evaluated using uni- and multivariate optimization strategies, based on the use of experimental factorial designs. The coating of the SPME fibre, together with the sampling mode and the temperature were the factors playing a major influence on the efficiency of the extraction. Under final conditions, 1.5 mL of milk and 8.5 mL of ultrapure water were poured in a glass vessel, which was closed and immersed in a water boiling bath. A poly(dimethylsiloxane)-divinylbenzene (PDMS-DVB) coated fibre was exposed directly to the diluted sample for 40 min. After that, the fibre was desorbed in the injector of the GC-MS system for 3 min. The optimized method provided limits of quantification (LOQs) between 0.2 and 1 microg L(-1) and a good linearity in the range between 1 and 250 microg L(-1). The inter-day precision remained below 15% for all compounds in spiked whole milk. The efficiency of the extraction changed for whole, semi-skimmed and skimmed milk; however, no differences were noticed among the relative recoveries achieved for milk samples, from different brands, with the same fat content. Copyright 2010 Elsevier B.V. All rights reserved.