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Surface and Interface Analysis: SIA

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https://www.readbyqxmd.com/read/28584389/low-temperature-plasma-for-the-preparation-of-crater-walls-for-compositional-depth-profiling-of-thin-inorganic-multilayers
#1
Shin Muramoto, Joe Bennett
An indirect, compositional depth profiling of an inorganic multilayer system using a helium low temperature plasma (LTP) containing 0.2% (v/v) SF6 was evaluated. A model multilayer system consisting of four 10 nm layers of silicon separated by four 50 nm layers of tungsten was plasma-etched for (10, 20, and 30) s at substrate temperatures of (50, 75, and 100) °C to obtain crater walls with exposed silicon layers that were then visualized using time-of-flight secondary ion mass spectrometry (ToF-SIMS) to determine plasma-etching conditions that produced optimum depth resolutions...
June 2017: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/28751796/calculations-of-electron-inelastic-mean-free-paths-xi-data-for-liquid-water-for-energies-from-50-ev-to-30-kev
#2
H Shinotsuka, B Da, S Tanuma, H Yoshikawa, C J Powell, D R Penn
We calculated electron inelastic mean free paths (IMFPs) for liquid water from its optical energy-loss function (ELF) for electron energies from 50 eV to 30 keV. These calculations were made with the relativistic full Penn algorithm (FPA) that has been used for previous IMFP and electron stopping-power calculations for many elemental solids. We also calculated IMFPs of water with three additional algorithms: the relativistic single-pole approximation (SPA), the relativistic simplified SPA, and the relativistic extended Mermin method...
April 2017: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/27087712/a-technique-for-calculation-of-shell-thicknesses-for-core-shell-shell-nanoparticles-from-xps-data
#3
David J H Cant, Yung-Chen Wang, David G Castner, Alexander G Shard
This paper extends a straightforward technique for the calculation of shell thicknesses in core-shell nanoparticles to the case of core-shell-shell nanoparticles using X-ray Photoelectron Spectroscopy (XPS) data. This method can be applied by XPS analysts and does not require any numerical simulation or advanced knowledge, although iteration is required in the case where both shell thicknesses are unknown. The standard deviation in the calculated thicknesses vs simulated values is typically less than 10%, which is the uncertainty of the electron attenuation lengths used in XPS analysis...
May 2016: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/27134321/tof-sims-analysis-of-a-polymer-microarray-composed-of-poly-meth-acrylates-with-c6-derivative-pendant-groups
#4
Andrew L Hook, David J Scurr
Surface analysis plays a key role in understanding the function of materials, particularly in biological environments. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) provides highly surface sensitive chemical information that can readily be acquired over large areas and has, thus, become an important surface analysis tool. However, the information-rich nature of ToF-SIMS complicates the interpretation and comparison of spectra, particularly in cases where multicomponent samples are being assessed...
April 2016: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/28824213/probing-the-lipid-chemistry-of-neurotoxin-induced-hippocampal-lesions-using-multimodal-imaging-mass-spectrometry
#5
Jörg Hanrieder, Oskar Karlsson, Eva Brittebo, Per Malmberg, Andrew G Ewing
The environmental toxin β-N-methylamino-L-alanine (BMAA) has been causatively linked to neurodegenerative disease pathology. In a rat model, neonatal BMAA exposure resulted in selective uptake in the hippocampal formation and caused learning and memory impairments in adult animals. Moreover, high dose neonatal BMAA exposure resulted in formation of protein inclusions in the CA1 region of the adult hippocampus. However the mechanism underlying BMAA induced neuropathology remains elusive. Imaging mass spectrometry is a powerful method for spatial interrogation of biochemical distribution in biological tissue with high chemical specificity...
November 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/28649151/quasi-simultaneous-acquisition-of-nine-secondary-ions-with-seven-detectors-on-nanosims50l-application-to-biological-samples
#6
Christelle Guillermier, Matthew L Steinhauser, Claude P Lechene
We employed a method of electrostatic peak switching allowing for the quasi-simultaneous measurement of (16)O, (18)O, C2H, C2D,(12)C(14)N, (13)C(14)N, (12)C(15)N, P, and S with the NanoSIMS 50L instrument to derive ratios for D/H, (13)C/(12)C, (18)O/(16)O, and (15)N/(14)N from biological samples. This approach involves two steps: (i) derivation of the D/H ratio from measurements of C2D and C2H and (ii) switching of the voltage on deflection plates located in front of two detectors. The method is reliable and easy to set up compared with the magnetic peak-switching mode usually used to perform this type of analysis...
November 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26494930/investigations-into-the-interactions-of-a-maldi-matrix-with-organic-thin-films-using-c60-sims-depth-profiling
#7
Jordan O Lerach, Selda Keskin, Nicholas Winograd
Molecular depth profiling of multilayer organic films is now an established protocol for cluster secondary ion mass spectrometry (SIMS). This unique capability is exploited here to study the ionization mechanism associated with matrix-enhanced SIMS and possibly matrix assisted laser desorption/ionization (MALDI). Successful depth profiling experiments were performed on model bi-layer systems using 2,5-dihydroxybenzoic acid (DHB) as the matrix with dipalmitoylphosphatidylcholine (DPPC) or phenylalanine (PHE)...
November 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26379342/quantitative-imaging-of-inositol-distribution-in-yeast-using-multi-isotope-imaging-mass-spectrometry-mims
#8
A Saiardi, C Guillermier, O Loss, J C Poczatek, C Lechene
Despite the widely recognized importance of the several species of inositol polyphosphates in cell biology, inositol has not been successfully imaged and quantified inside cells using traditional spectrophotometry. Multi-isotope imaging mass spectrometry (MIMS) technology, however, has facilitated direct imaging and measurement of cellular inositol. After pulsing cells with inositol labeled with the stable isotope Carbon-13 ((13)C), the label was detected in subcellular volumes by MIMS. The tridimensional localization of (13)C within the cell illustrated cellular distribution and local accumulation of inositol...
November 1, 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26379341/approaches-to-increasing-analytical-throughput-of-human-samples-with-multi-isotope-imaging-mass-spectrometry
#9
Matthew L Steinhauser, Christelle Guillermier, Mei Wang, Claude P Lechene
Multi-isotope imaging mass spectrometry (MIMS) combines stable isotope tracers with the quantitative imaging of NanoSIMS ion microscopy. With extensive safety precedent, use of stable isotopes in MIMS applications opens the possibility of studying a wide array of biological questions in humans([1]). Here we describe a series of approaches to increase the effective analytical throughput for detecting rare nuclear labeling events with MIMS. At the level of sample preparation, cells in suspension were either smeared at high density or pelleted cells were embedded and sectioned to reach nuclear depth...
November 1, 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26379340/quantifying-cell-division-with-deuterated-water-and-multi-isotope-imaging-mass-spectrometry-mims
#10
Matthew L Steinhauser, Christelle Guillermier, Mei Wang, Claude P Lechene
Cell division is commonly quantified by the administration of nucleotide labels that are incorporated by the nucleotide salvage pathway. A new approach uses precursors of the de novo nucleotide synthesis pathway, such as labeled water or glucose. Because such precursors are not specific for DNA synthesis, studies utilizing this approach have analyzed isolated genomic DNA to exclude nonspecific background labeling. We hypothesized that pulse-chase administration of stable isotope labeled water would result in sufficient nuclear labeling to enable discrimination of recently divided cells by quantitative ion microscopy...
November 1, 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26379339/study-of-protein-and-rna-in-dendritic-spines-using-multi-isotope-imaging-mass-spectrometry-mims
#11
H Brismar, A Aperia, L Westin, J Moy, M Wang, C Guillermier, C Poczatek, C Lechene
The classical view of neuronal protein synthesis is that proteins are made in the cell body and then transported to their functional sites in the dendrites and the dendritic spines. Indirect evidence, however, suggests that protein synthesis can directly occur in the distal dendrites, far from the cell body. We are developing protocols for dual labeling of RNA and proteins using (15)N-uridine and (18)O- or (13)C-leucine pulse chase in cultured neurons to identify and localize both protein synthesis and fate of newly synthesized proteins...
November 1, 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26379338/quantitative-imaging-of-selenoprotein-with-multi-isotope-imaging-mass-spectrometry-mims
#12
Shiow-Shih Tang, Christelle Guillermier, Mei Wang, Joseph Collin Poczatek, Noriyuki Suzuki, Joseph Loscalzo, Claude Lechene
Multi-isotope imaging mass spectrometry (MIMS) allows high resolution quantitative imaging of protein and nucleic acid synthesis at the level of a single cell using stable isotope labels. We employed MIMS to determine the compartmental localization of selenoproteins tagged with stable isotope selenium compounds in human aortic endothelial cells (HAEC), and to compare the efficiency of labeling (to determine the ideal selenium source) from these compounds: [(82)Se]-selenite, [(77)Se]-seleno-methionine, and [(76)Se]-methyl-selenocysteine...
November 1, 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26379337/detection-of-immunolabels-with-multi-isotope-imaging-mass-spectrometry-mims
#13
G Thiery-Lavenant, C Guillermier, M Wang, C Lechene
We have developed a method that combines the use of stable isotopes, MIMS and antibody. We began with using well-established antibodies, anti-actin and anti-synaptophysin, in mouse intestinal cells. We extended the method to an immunogold assay to specifically localize Ribeye, a major protein component of retina synaptic ribbons, or to localize a synaptic vesicle-containing protein, synaptophysin. Both are localized in presynaptic nerve terminal of photoreceptors cells in retina. Our results show that by MIMS analysis of the Au signal we can directly identify antibodies tagged with non amplified 1...
November 1, 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26379336/effect-of-an-anti-depressant-on-mouse-hippocampus-protein-turnover-using-mims
#14
M D Filiou, J Moy, M Wang, C Guillermier, J C Poczatek, C Turck, C Lechene
Although antidepressants have been used in the treatment of affective disorders for over fifty years, the precise mechanism of their action remains unknown. Treatment regimens are based by and large on empirical parameters and characterized by a trial and error scheme. A better understanding of the mechanisms involved in antidepressant drug response is of fundamental importance for the development of new compounds that have a higher success rate and specificity. In order to elucidate the molecular pathways involved in the action of antidepressants, we wish to identify brain areas, cell types, and organelles that are targeted by antidepressant treatment in mice...
November 1, 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26379335/brain-stem-cell-division-and-maintenance-studied-using-multi-isotope-imaging-mass-spectrometry-mims
#15
G Enikolopov, C Guillermier, M Wang, L Trakimas, M Steinhauser, C Lechene
New neurons are continuously produced from neural stem cells in specific regions of the adult brain of animals and humans. In the hippocampus, a region crucial for cognitive function, neurogenesis responds to a multitude of extrinsic stimuli; emerging evidence indicates that it may be important for behavior, pathophysiology, brain repair, and response to drugs. We have developed an approach to identify and quantify the cellular targets of pro- and anti-neurogenic stimuli, based on reporter transgenic mouse lines in which neural stem and progenitor cells or their progeny are marked by fluorescent proteins...
November 1, 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/26207076/molecular-imaging-of-biological-tissue-using-gas-cluster-ions
#16
Hua Tian, Andreas Wucher, Nicholas Winograd
An Ar n (+) (n = 1-6000) gas cluster ion source has been utilized to map the chemical distribution of lipids in a mouse brain tissue section. We also show that the signal from high mass species can be further enhanced by doping a small amount of CH4 into the Ar cluster to enhance the ionization of several biologically important molecules. Coupled with secondary ion mass spectrometry instrumentation which utilizes a continuous Ar cluster ion projectile, maximum spatial resolution and maximum mass resolution can be achieved at the same time...
November 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/25931643/dye-enhanced-imaging-of-mammalian-cells-with-sims
#17
Anna Bloom, Nicholas Winograd
A major limitation of SIMS studies of cells is the limited number of molecules available for detection. This study examines the possibility of utilizing a molecular tag which is easily identifiable using SIMS and does not interfere with the mass spectra of commonly identified cellular components, to aid in the visualization of specific cellular organelles. Here, a fluorescent, nuclear stain (Hoechst 33342) was used to allow for verification of the staining protocols prior to SIMS analysis. The stain was successfully chemically imaged within the nuclear region of a glutaraldehyde fixed bovine aortic endothelial cell...
November 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/25918451/tof-sims-imaging-of-lipids-and-lipid-related-compounds-in-drosophila-brain
#18
Nhu T N Phan, John S Fletcher, Peter Sjövall, Andrew G Ewing
Drosophila melanogaster (fruit fly) has a relatively simple nervous system but possesses high order brain functions similar to humans. Therefore, it has been used as a common model system in biological studies, particularly drug addiction. Here, the spatial distribution of biomolecules in the brain of the fly was studied using time-of flight secondary ion mass spectrometry (ToF-SIMS). Fly brains were analyzed frozen to prevent molecular redistribution prior to analysis. Different molecules were found to distribute differently in the tissue, particularly the eye pigments, diacylglycerides, and phospholipids, and this is expected to be driven by their biological functions in the brain...
November 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/25918450/analysis-of-liposome-model-systems-by-time-of-flight-secondary-ion-mass-spectrometry
#19
Jelena Lovrić, Jacqueline D Keighron, Tina B Angerer, Xianchan Li, Per Malmberg, John S Fletcher, Andrew G Ewing
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is an important technique for studying chemical composition of micrometer scale objects due to its high spatial resolution imaging capabilities and chemical specificity. In this work we focus on the application of ToF-SIMS to gain insight into the chemistry of micrometer size liposomes as a potential model for neurotransmitter vesicles. Two models of giant liposomes were analyzed: histamine and aqueous two phase system (ATPS)-containing liposomes. Characterization of the internal structure of single fixed liposomes was done both with the Bi3 (+) and C60 (+) ion sources...
November 2014: Surface and Interface Analysis: SIA
https://www.readbyqxmd.com/read/25892830/dual-beam-organic-depth-profiling-using-large-argon-cluster-ion-beams
#20
M Holzweber, A G Shard, H Jungnickel, A Luch, Wes Unger
Argon cluster sputtering of an organic multilayer reference material consisting of two organic components, 4,4'-bis[N-(1-naphthyl-1-)-N-phenyl- amino]-biphenyl (NPB) and aluminium tris-(8-hydroxyquinolate) (Alq3), materials commonly used in organic light-emitting diodes industry, was carried out using time-of-flight SIMS in dual beam mode. The sample used in this study consists of a ∽400-nm-thick NPB matrix with 3-nm marker layers of Alq3 at depth of ∽50, 100, 200 and 300 nm. Argon cluster sputtering provides a constant sputter yield throughout the depth profiles, and the sputter yield volumes and depth resolution are presented for Ar-cluster sizes of 630, 820, 1000, 1250 and 1660 atoms at a kinetic energy of 2...
October 2014: Surface and Interface Analysis: SIA
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