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High Resolution Multimodal Chemical Imaging Platform for Organics and Inorganics
Kim, Songkil,Trofimov, Artem,Khanom, Fouzia,Stern, Lewis,Lamberti, William,Colby, Robert,Abmayr, David,Belianinov, Alex,Ovchinnikova, Olga S. American Chemical Society 2019 ANALYTICAL CHEMISTRY - Vol.91 No.19
<P>Chemical analysis at the nanoscale is critical to advance our understanding of materials and systems from medicine and biology to material science and computing. Macroscale-observed phenomena in these systems are in the large part driven by processes that take place at the nanoscale and are highly heterogeneous. Therefore, there is a clear need to develop a new technology that enables correlative imaging of material functionalities with nanoscale spatial and chemical resolutions that will enable us to untangle the structure-function relationship of functional materials. Therefore, here, we report on the analytical figures of merit of the newly developed correlative chemical imaging technique of helium ion microscopy coupled with secondary ion mass spectrometry (HIM-SIMS) that enables multimodal topographical/chemical imaging of organic and inorganic materials at the nanoscale. In HIM-SIMS, a focused ion beam acts as a sputtering and ionization source for chemical analysis along with simultaneous high-resolution surface imaging, providing an unprecedented level of spatial resolution for gathering chemical information on organic and inorganic materials. In this work, we demonstrate HIM-SIMS as a platform for a next-generation tool for an in situ material design and analysis capable of down to 8 nm spatial resolution chemical imaging, layered metal structure imaging in depth profiling, single graphene layer detection, and spectral analysis of metals, metal oxides, and polymers.</P> [FIG OMISSION]</BR>
Matrix stiffness-modulated proliferation and secretory function of the airway smooth muscle cells.
Shkumatov, Artem,Thompson, Michael,Choi, Kyoung M,Sicard, Delphine,Baek, Kwanghyun,Kim, Dong Hyun,Tschumperlin, Daniel J,Prakash, Y S,Kong, Hyunjoon American Physiological Society 2015 American journal of physiology. Lung cellular and Vol.308 No.11
<P>Multiple pulmonary conditions are characterized by an abnormal misbalance between various tissue components, for example, an increase in the fibrous connective tissue and loss/increase in extracellular matrix proteins (ECM). Such tissue remodeling may adversely impact physiological function of airway smooth muscle cells (ASMCs) responsible for contraction of airways and release of a variety of bioactive molecules. However, few efforts have been made to understand the potentially significant impact of tissue remodeling on ASMCs. Therefore, this study reports how ASMCs respond to a change in mechanical stiffness of a matrix, to which ASMCs adhere because mechanical stiffness of the remodeled airways is often different from the physiological stiffness. Accordingly, using atomic force microscopy (AFM) measurements, we found that the elastic modulus of the mouse bronchus has an arithmetic mean of 23.1 ± 14 kPa (SD) (median 18.6 kPa). By culturing ASMCs on collagen-conjugated polyacrylamide hydrogels with controlled elastic moduli, we found that gels designed to be softer than average airway tissue significantly increased cellular secretion of vascular endothelial growth factor (VEGF). Conversely, gels stiffer than average airways stimulated cell proliferation, while reducing VEGF secretion and agonist-induced calcium responses of ASMCs. These dependencies of cellular activities on elastic modulus of the gel were correlated with changes in the expression of integrin-관1 and integrin-linked kinase (ILK). Overall, the results of this study demonstrate that changes in matrix mechanics alter cell proliferation, calcium signaling, and proangiogenic functions in ASMCs.</P>
Tagir Makhmutov,Nikolay Razumov,Artem Kim,Nikolay Ozerskoy,Alina Mazeeva,Anatoliy Popovich 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.1
Spherical powders of CoCrFeNiMnW0.25high-entropy alloy were obtained from elemental powders by mechanical alloying(MA) at various energy modes followed by plasma spheroidization. Samples obtained from low-energy MA-powdershave an inhomogeneous microstructure and phase composition. Samples obtained from MA-powders with homogeneousstructures have a high degree of sphericity and chemical homogeneity; the face-centered cubic solid solution represents thephase composition of the powders. The resulting powders can be used in powder-based additive manufacturing technologies.
Water NMR for Polarized $^{129}$Xe Signal Calibration with a 283 G Magnetic Field
Vladimir Vladimirovich KAVTANYUK,Joshua Artem TAN,Wooyoung KIM,선용근,Seongwoo PARK,Jieun SO,Yu ANDO 한국물리학회 2016 New Physics: Sae Mulli Vol.66 No.5
We present measurements of water nuclear magnetic resonance (NMR) for polarized $^{129}$Xe signal calibration. We used a permanent magnet having an average homogeneous space in the center and a field of 283$\pm$2 G. A Pick-up coil was orthogonally inserted inside the RF coil. Oscillating RF and pick-up signals were managed by using Tecmag Apollo LF-1. Two LC circuits (the RF and the pick-up) were set to a resonance frequency of 1.205 MHz by manipulating a capacitance system. The nuclear spins of the protons in water are flipped and precess with the Larmor frequency around the direction of the static field. Tha application of an oscillating magnetic field with the Larmor frequency perpendicular to the static magnetic field leads to resonance absorption and emission of the electromagnetic energy. The emitted resonance signals are acquired by the pick-up coil and sent to the Apollo for analysis. In the future, the water NMR signal will be used for determining the polarization of $^{129}$Xe.
Free and forced Barkhausen noises in magnetic thin film based cross-junctions
Elzwawy, Amir,Talantsev, Artem,Kim, CheolGi Elsevier 2018 Journal of magnetism and magnetic materials Vol.458 No.-
<P><B>Abstract</B></P> <P>Barkhausen noise, driven by thermal fluctuations in stationary magnetic field, and Barkhausen jumps, driven by sweeping magnetic field, are demonstrated to be effects of different orders of magnitude. The critical magnetic field for domain walls depinning, followed by avalanched and irreversible magnetization jumps, is determined. Magnetoresistive response of NiFe/M/NiFe (M = Au, Ta, Ag) trilayers to stationary and sweeping magnetic field is studied by means of anisotropic magnetoresistance (AMR) and planar Hall effect (PHE) measurements. Thermal fluctuations result in local and reversible changes of magnetization of the layers in thin film magnetic junctions, while the sweeping magnetic field results in reversible and irreversible avalanched domain motion, dependently on the ratio between the values of sweeping magnetic field and domain wall depinning field. The correlation between AMR and PHE responses to Barkhausen jumps is studied. The value of this correlation is found to be dependent on the <I>α</I> angle between the directions of magnetic field and current path.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Planar Hall effect (PHE) is studied together with anisotropic MR (AMR). </LI> <LI> The jumps on PHE and AMR vs magnetic field curves are asynchronous. </LI> <LI> The correlation between PHE and AMR jumps is governed by magnetic field direction. </LI> <LI> At low fields the combination of AMR and GMR effects results in linear response. </LI> <LI> The sensor’s noise is reduced, if the Au instead of Ag is used as an interlayer material. </LI> </UL> </P>
Production of Hyperpolarized 129Xe Using Spin Exchange Optical Pumping
Vladimir Vladimirovich KAVTANYUK,Wooyoung KIM,Yu ANDO,Sergey Chebotaryov,Yonggeun SEON,Joshua Artem TAN 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.10
We present a constructed setup for polarizing 129Xe noble gas. Hyperpolarized 129Xe has been obtained via spin exchange with an optically pumped rubidium vapor. Optical pumping is based on polarizing the valence electron of rubidium by the resonant absorption of a circularly polarized laser light. The magnetic field of 30 G was used for obtaining 129Xe polarization. The apparatus for detecting polarization is a nuclear magnetic resonance spectrometer. The highest 129Xe polarization of 54% has been obtained using 60 W circularly polarized laser light with wavelength of 794.7 nm. The measured longitudinal relaxation time of the hyperpolarized 129Xe was 72.3 minutes.