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Secondary ion mass spectrometry

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https://www.readbyqxmd.com/read/28346904/single-particle-mass-spectral-signatures-from-vehicle-exhaust-particles-and-the-source-apportionment-of-on-line-pm2-5-by-single-particle-aerosol-mass-spectrometry
#1
Jian Yang, Shexia Ma, Bo Gao, Xiaoying Li, Yanjun Zhang, Jing Cai, Mei Li, Ling'ai Yao, Bo Huang, Mei Zheng
In order to accurately apportion the many distinct types of individual particles observed, it is necessary to characterize fingerprints of individual particles emitted directly from known sources. In this study, single particle mass spectral signatures from vehicle exhaust particles in a tunnel were performed. These data were used to evaluate particle signatures in a real-world PM2.5 apportionment study. The dominant chemical type originating from average positive and negative mass spectra for vehicle exhaust particles are EC species...
March 24, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28345909/rapid-and-simultaneous-analysis-of-360-pesticides-in-brown-rice-spinach-orange-and-potato-using-microbore-gc-ms-ms
#2
Jonghwa Lee, Leesun Kim, Yongho Shin, Junghak Lee, Jiho Lee, Eunhye Kim, Joon-Kwan Moon, Jeong-Han Kim
A multi-residue method for simultaneous and rapid analysis of 360 pesticides in representative agricultural produce (brown rice, orange, spinach, and potato) was developed using a modified QuEChERS procedure combined with gas chromatography tandem mass spectrometry (GC-MS/MS). Selected reaction monitoring transition parameters (e.g., collision energy, precursor and product ions) in MS/MS were optimized to achieve the best selectivity and sensitivity for a wide range of GC amenable pesticides. A short (20 m) microbore (0...
March 27, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28332827/subcellular-chemical-imaging-of-antibiotics-in-single-bacteria-using-c60-secondary-ion-mass-spectrometry
#3
Hua Tian, David A Six, Thomas Krucker, Jennifer A Leeds, Nicholas Winograd
The inherent difficulty of discovering new and effective antibacterials and the rapid development of resistance particularly in Gram-negative bacteria, illustrates the urgent need for new methods that enable rational drug design. Here we report the development of 3D imaging cluster secondary ion mass spectrometry (SIMS) as a label-free approach to chemically map small molecules in aggregated and single Escherichia coli cells, with ~300 nm spatial resolution and high chemical sensitivity. The feasibility of quantitative analysis was explored, and a non-linear relationship between treatment dose and signal for tetracycline and ampicillin, two clinically-used antibacterials, was observed...
March 23, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28328033/effects-of-molecular-weight-and-cationization-agent-on-the-sensitivity-of-bi-cluster-secondary-ion-mass-spectrometry
#4
Makiko Fujii, Rie Shishido, Takaya Satoh, Shigeru Suzuki, Jiro Matsuo
RATIONALE: Bi cluster secondary ion mass spectrometry (SIMS) is one of the most promising tools for precise analysis of synthetic polymers. However, the sensitivity in the high-mass region is still insufficient compared with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Accordingly, the effects of metal assistance (cationization agents) were investigated in this study. METHODS: To investigate the effects caused by varying the ionization agent, three different polyethylene glycol (PEG) samples were prepared, one with an Ag-deposited film, and two others mixed with Ag and Na, respectively...
July 30, 2016: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28306235/gcib-tof-sims-high-resolution-imaging-of-cardiolipin-speciation-in-the-brain-identification-of-molecular-losses-after-traumatic-injury
#5
Hua Tian, Louis J Sparvero, Andrew A Amoscato, Anna Bloom, Hulya Bayir, Valerian E Kagan, Nicholas Winograd
Gas cluster ion beam secondary ion mass spectrometry (GCIB-SIMS) has shown the full potential of mapping intact lipids in biological systems with better than 10 µm lateral resolution. This study investigated further the capability of GCIB-SIMS in imaging high-mass signals from intact cardiolipin (CL) and gangliosides in normal brain and the effect of a controlled cortical impact model (CCI) of traumatic brain injury (TBI) on their distribution. A combination of enzymatic and chemical treatments was employed to suppress the signals from the most abundant phospholipids (phosphatidylcholine (PC) and phosphatidylethanolamine (PE)) and enhance the signals from the low abundance CLs and gangliosides to allow their GCIB-SIMS detection at 8 and 16 µm spatial resolution...
March 17, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28301944/orientation-and-characterization-of-immobilized-antibodies-for-improved-immunoassays-review
#6
Nicholas G Welch, Judith A Scoble, Benjamin W Muir, Paul J Pigram
Orientation of surface immobilized capture proteins, such as antibodies, plays a critical role in the performance of immunoassays. The sensitivity of immunodiagnostic procedures is dependent on presentation of the antibody, with optimum performance requiring the antigen binding sites be directed toward the solution phase. This review describes the most recent methods for oriented antibody immobilization and the characterization techniques employed for investigation of the antibody state. The introduction describes the importance of oriented antibodies for maximizing biosensor capabilities...
March 16, 2017: Biointerphases
https://www.readbyqxmd.com/read/28283715/label-free-visualization-of-nilotinib-functionalized-gold-nanoparticles-within-single-mammalian-cells-by-c60-sims-imaging
#7
Anna N Bloom, Hua Tian, Christian Schoen, Nicholas Winograd
Obtaining a comprehensive grasp of the behavior and interaction of pharmaceutical compounds within single cells provides some of the fundamental details necessary for more effective drug development. In particular, the changes ensuing in the carrier, drug, and host environment in targeted drug therapy applications must be explored in greater detail, as these are still not well understood. Here, nilotinib-functionalized gold nanoparticles are examined within single mammalian cells with use of imaging cluster secondary ion mass spectrometry in a model study designed to enhance our understanding of what occurs to these particles once that have been internalized...
March 10, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28267998/background-correction-in-separation-techniques-hyphenated-to-high-resolution-mass-spectrometry-thorough-correction-with-ms-scans-recorded-as-profile-spectra
#8
Guillaume L Erny, Tanize Acunha, Carolina Simó, Alejandro Cifuentes, Arminda Alves
Separation techniques hyphenated with high-resolution mass spectrometry have been a true revolution in analytical separation techniques. Such instruments not only provide unmatched resolution, but they also allow measuring the peaks accurate masses that permit identifying monoisotopic formulae. However, data files can be large, with a major contribution from background noise and background ions. Such unnecessary contribution to the overall signal can hide important features as well as decrease the accuracy of the centroid determination, especially with minor features...
March 1, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28265969/on-the-sims-ionization-probability-of-organic-molecules
#9
Nicholas J Popczun, Lars Breuer, Andreas Wucher, Nicholas Winograd
The prospect of improved secondary ion yields for secondary ion mass spectrometry (SIMS) experiments drives innovation of new primary ion sources, instrumentation, and post-ionization techniques. The largest factor affecting secondary ion efficiency is believed to be the poor ionization probability (α(+)) of sputtered material, a value rarely measured directly, but estimated to be in some cases as low as 10(-5). Our lab has developed a method for the direct determination of α(+) in a SIMS experiment using laser post-ionization (LPI) to detect neutral molecular species in the sputtered plume for an organic compound...
March 6, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28265624/charge-attachment-induced-transport-bulk-and-grain-boundary-diffusion-of-potassium-in-prmno3
#10
Johannes Martin, Melanie Gräf, Thilo Kramer, Christian Jooss, Min-Ju Choe, Katsuyo Thornton, Karl-Michael Weitzel
The transport of potassium through praseodymium-manganese oxide (PrMnO3; PMO) has been investigated by means of the charge attachment induced transport (CAIT) technique. To this end, potassium ions have been attached to the front side of a 250 nm thick sample of PMO. The majority of the potassium ions become neutralized at the surface of the PMO, while some of the potassium ions diffuse through. Ex situ analysis of the sample by time-of-flight secondary ion mass spectrometry (ToF-SIMS) reveals pronounced concentration profiles of the potassium, which is indicative of diffusion...
March 7, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28253633/fatty-acids-penetration-into-human-skin-ex-vivo-a-tof-sims-analysis-approach
#11
Vytis Čižinauskas, Nicolas Elie, Alain Brunelle, Vitalis Briedis
Linoleic, oleic, palmitoleic, palmitic, and stearic fatty acids (FAs) are commonly used in dermatological formulations. They differ by their structure, presence in the skin, and mode of application in pharmaceuticals and cosmetics compounding. These FAs are also known as chemical penetration enhancers, but their mechanisms of penetration enhancement and effect on barrier characteristics of the skin require additional study. In this study, the authors conducted an ex vivo analysis of the distribution of lipid components in the epidermis and dermis of human skin after applying individual FAs...
March 2, 2017: Biointerphases
https://www.readbyqxmd.com/read/28239963/characterization-of-complex-heterogeneous-lipid-a-samples-using-hplc-ms-ms-technique-ii-structural-elucidation-of-non-phosphorylated-lipid-a-by-negative-ion-mode-tandem-mass-spectrometry
#12
Viktor Sándor, Anikó Kilár, Ferenc Kilár, Béla Kocsis, Ágnes Dörnyei
Non-phosphorylated lipid A species confer reduced inflammatory potential for the bacteria. Knowledge on their chemical structure and presence in bacterial pathogens may contribute to the understanding of bacterial resistance and activation of the host innate immune system. In this study, we report the fragmentation pathways of negatively charged, non-phosphorylated lipid A species under low-energy collision-induced dissociation conditions of an electrospray ionization quadrupole time-of-flight instrument. Charge-promoted consecutive and competitive eliminations of the acyl chains and cross-ring cleavages of the sugar residues were observed...
August 2016: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28238440/the-proteolytic-system-of-pineapple-stems-revisited-purification-and-characterization-of-multiple-catalytically-active-forms
#13
André Matagne, Laetitia Bolle, Rachida El Mahyaoui, Danielle Baeyens-Volant, Mohamed Azarkan
Crude pineapple proteases extract (aka stem bromelain; EC 3.4.22.4) is an important proteolytic mixture that contains enzymes belonging to the cysteine proteases of the papain family. Numerous studies have been reported aiming at the fractionation and characterization of the many molecular species present in the extract, but more efforts are still required to obtain sufficient quantities of the various purified protease forms for detailed physicochemical, enzymatic and structural characterization. In this work, we describe an efficient strategy towards the purification of at least eight enzymatic forms...
February 23, 2017: Phytochemistry
https://www.readbyqxmd.com/read/28230323/simultaneous-determination-of-seven-nitrogen-containing-phenyl-ethers-in-cosmetics-by-gas-chromatography-with-mass-spectrometry-and-dispersive-solid-phase-extraction
#14
Jiale Huang, Langjun Zhou, Zhiqing Xun, Qiang Wang, Senyu Lin, Xindong Guo, Yongtong Cai
An analytical method was established for the simultaneous determination of seven nitrogen-containing phenyl ethers (2-anisidine, 3-anisidine, 4-anisidine, 2-nitroanisole, 3-nitroanisole, 4-nitroanisole and 3,3'-dimethoxybenzidine) in cosmetics by gas chromatography with mass spectrometry in this work. The samples were extracted with ethyl acetate and purified with primary secondary amine during the dispersed solid phase extraction. The analytes were separated by a DB-17MS column and detected in the electron ionization mode of mass spectrometry in the selected ions monitoring mode...
February 23, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28220763/exfoliation-of-black-phosphorus-in-ionic-liquids
#15
Miyeon Lee, Arup Kumer Roy, Seongho Jo, Yujin Choi, Ari Chae, Bongsoo Kim, Sung Yong Park, Insik In
We report the characterization and formation of sonication-assisted liquid phase exfoliation of bulk black phosphorus (BP) crystals with the incorporation of two representative ionic liquids (ILs) ([Emim][Tf2N] and [Bmim][Tf2N]) as green dispersing media was attempted, which resulted in stable dispersion of multi-layer BP flakes with unsuspected high oxidation resistance and chemical/structural integrity due to the presence of IL layer on top of BP flakes. There are two unveiled issues for the generation of BP dispersion in ILs...
March 24, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28219030/in-situ-synthesized-cadmium-sulfide-nanowire-photosensor-with-a-parylene-passivation-layer-for-chemiluminescent-immunoassays
#16
Ju-Hee Im, Hong-Rae Kim, Byoung-Gi An, Young Wook Chang, Min-Jung Kang, Tae-Geol Lee, Jin Gyeng Son, Jae-Gwan Park, Jae-Chul Pyun
The direct in situ synthesis of cadmium sulfide (CdS) nanowires (NWs) was presented by direct synthesis of CdS NWs on the gold surface of an interdigitated electrode (IDE). In this work, we investigated the effect of a strong oxidant on the surfaces of the CdS NWs using X-ray photoelectron spectroscopy, transmission electron microscopy, and time-of-flight secondary ion mass spectrometry. We also fabricated a parylene-C film as a surface passivation layer for in situ-synthesized CdS NW photosensors and investigated the influence of the parylene-C passivation layer on the photoresponse during the coating of parylene-C under vacuum using a quartz crystal microbalance and a photoanalyzer...
June 15, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28211996/alternating-current-electrophoretic-deposition-for-the-immobilization-of-antimicrobial-agents-on-titanium-implant-surfaces
#17
Annabel Braem, Katrijn De Brucker, Nicolas Delattin, Manuela S Killian, Maarten B J Roeffaers, Tomohiko Yoshioka, Satoshi Hayakawa, Patrik Schmuki, Bruno P A Cammue, Sannakaisa Virtanen, Karin Thevissen, Bram Neirinck
One prominent cause of implant failure is infection; therefore, research is focusing on developing surface coatings that render the surface resistant to colonization by micro-organisms. Permanently attached coatings of antimicrobial molecules are of particular interest because of the reduced cytoxicity and lower risk of developing resistance compared to controlled release coatings. In this study, we focus on the chemical grafting of bioactive molecules on titanium. To concentrate the molecules at the metallic implant surface, we propose electrophoretic deposition (EPD) applying alternating current (AC) signals with an asymmetrical wave shape...
March 6, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28211359/electrodeposition-of-wo3-nanoparticles-into-surface-mounted-metal-organic-framework-hkust-1-thin-films
#18
Hyeonseok Yoo, Alexander Welle, Wei Guo, Jinsub Choi, Engelbert Redel
We describe a novel procedure to fabricate WO3@surface-mounted metal-organic framework (SURMOF) hybrid materials by electrodeposition of WO3 nanoparticles into HKUST-1, also termed Cu3(BTC)2 SURMOFs. These materials have been characterized using x-ray diffraction, time-of-flight secondary ion mass spectrometry, scanning electron microscopy, x-ray photoelectron spectroscopy as well as linear sweep voltammetry. The WO3 semiconductor/SURMOF heterostructures were further tested as hybrid electrodes in their performance for hydrogen evolution reaction from water...
March 17, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28210007/annealing-stability-study-of-co20fe60b20-mgo-co20fe60b20-perpendicular-magnetic-tunnel-junctions
#19
P J Chen, M Zhu, S Tibus, T Dyer, J Piccirillo, B Ocker, R D Shull
A full Co20Fe60B20\MgO\ Co20Fe60B20 perpendicular magnetic tunnel junction (pMTJ) with (Co\Pt) multilayers as pinning layers and different functional multilayers stacks were made and annealed at different temperatures. The tunneling magnetoresistance ratio (TMR) and MgO barrier resistance-area product (RA) were measured and analyzed as a function of annealing temperature. The TMR of pMTJs dramatically declines with increasing annealing temperatures from 320 °C to 400 °C while the RA increases with temperature from 375 °C to 450 °C...
January 18, 2017: Journal of Physics D: Applied Physics
https://www.readbyqxmd.com/read/28195489/composition-and-stability-of-plasma-polymer-films-exhibiting-vertical-chemical-gradients
#20
Patrick Rupper, Marianne Vandenbossche, Laetitia Bernard, Dirk Hegemann, Manfred Heuberger
Controlling the balance between stability and functional group density in grown plasma polymer films is the key to diverse applications such as drug release, tissue-engineered implants, filtration, contact lenses, microfluidics, electrodes, sensors, etc. Highly functional plasma polymer films typically show a limited stability in air or aqueous environments due to mechanisms like molecular reorganization, oxidation, and hydrolysis. Stabilization is achieved by enhancing cross-linking at the cost of the terminal functional groups such as -OH and -COOH, but also -NH2, etc...
February 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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