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21.
Oleh Shpotyuk Adam Ingram Zdenka Bujkov Peter Bal Yaroslav Shpotyuk Dmytro Slobodzyan Mariusz Wo
ny Catherine Boussard‐Pledel Bruno Bureau 《Polymer Engineering and Science》2019,59(12):2438-2442
The method of positron annihilation lifetime (PAL) spectroscopy was first employed to study atomic‐deficient free‐volume structure of nanocomposites prepared by high‐energy mechanical milling of glassy g‐As2Se3 in water solution of polyvinylpyrrolidone (PVP). The formalism of x3‐x2‐CDA (coupling decomposition algorithm) describing conversion of bound positron‐electron (positronium Ps) states into positron traps was applied to identify free‐volume elements in pelletized PVP‐capped g‐As2Se3 nanocomposite in respect to parent dry‐milled g‐As2Se3. Under wet milling, the internanoparticle Ps‐decaying sites in preferential PVP environment were shown to replace free‐volume positron traps in dry‐milled g‐As2Se3 with defect‐specific positron lifetime of 0.352 ns, corresponding to diatomic/triatomic vacancies in g‐As‐Se matrix. POLYM. ENG. SCI., 59:2438–2442, 2019. © 2019 Society of Plastics Engineers 相似文献
22.
Iryna Pohrelyuk Oleh Tkachuk Roman Proskurnyak Jan Guspiel Ewa Beltowska‐Lehman Jerzy Morgiel 《工业材料与腐蚀》2019,70(12):2320-2325
The corrosion behavior of oxynitrided Ti–6Al–4V alloy was investigated in the Ringer's solution (simulated body fluid) at a temperature of 37°C. The oxynitriding of the alloy was carried out by leaking controlled oxygen‐containing medium into the reaction chamber at the final stage of the nitride formation. It was determined that oxynitriding improved corrosion resistance of Ti–6Al–4V alloy as it provided lower corrosion current density by 1.3–1.5 times and higher corrosion potential. In this paper, we analyzed that the resistance of the double layer had increased with the increase of the oxygen content in titanium oxynitride. Its value was higher compared with untreated alloy, indicating higher corrosion resistance of the oxynitrided one. 相似文献
23.
Roman Golovchak Andrzej Kozdras Oleh Shpotyuk Sergey Kozyukhin Jean-Marc Saiter 《Journal of Materials Science》2009,44(15):3962-3967
Effect of long-term physical ageing (~18–21 years) in vitreous germanium selenides is studied using differential scanning
calorimetry method. It is compared with short-term physical ageing observed in these glasses earlier. Low compositional limit
of the non-ageing ability determined using old samples coincides with the onset of reversibility window obtained using short-term
aged samples of Ge–Se system by temperature modulated differential scanning calorimetry technique. 相似文献
24.
Ying Chen Pavel I. Reyes Ziqing Duan Gaurav Saraf Richard Wittstruck Yicheng Lu Olena Taratula Elena Galoppini 《Journal of Electronic Materials》2009,38(8):1605-1611
Zinc oxide (ZnO) and its ternary alloy magnesium zinc oxide (Mg
x
Zn1−x
O) are piezoelectric materials that can be used for high-quality-factor bulk acoustic wave (BAW) resonators operating at GHz
frequencies. Thin-film bulk acoustic resonators (TFBARs) are attractive for applications in advanced communication and in
various sensors as they offer the capability of monolithic integration of BAW resonators with radio-frequency integrated circuits
(RF ICs). In this paper we report Mg
x
Zn1−x
O-based TFBAR biosensors. The devices are built on Si substrates with an acoustic mirror consisting of alternating quarter-wavelength
silicon dioxide (SiO2) and tungsten (W) layers to isolate the TFBAR from the Si substrate. High-quality ZnO and Mg
x
Zn1−x
O thin films are achieved through a radio-frequency (RF) sputtering technique. Tuning of the device operating frequency is
realized by varying the Mg composition in the piezoelectric Mg
x
Zn1−x
O layer. Simulation results based on a transmission-line model of the TFBAR show close agreement with the experimental results.
ZnO nanostructures are grown on the TFBAR’s top surface using metal- organic chemical vapor deposition (MOCVD) to form the
nano-TFBAR sensor, which offers giant sensing area, faster response, and higher sensitivity over the planar sensor configuration.
Mass sensitivity higher than 103 Hz cm2/ng is achieved. In order to study the feasibility of the nano-TFBAR for biosensing, the nanostructured ZnO surfaces were
functionalized to selectively immobilize␣DNA, as verified by hybridization with its fluorescence-tagged DNA complement. 相似文献
25.
Generation of doubly charged vortex beam by concentrated loading of glass disks along their diameter
We show that a system of glass disks compressed along their diameters enables one to induce a doubly charged vortex beam in the emergent light when the incident light is circularly polarized. Using such a disk system, one can control the efficiency of conversion of the spin angular momentum to the orbital angular momentum by a loading force. The consideration presented here can be extended for the case of crystalline materials with high optical damage thresholds in order to induce high-power vortex beams. 相似文献
26.
Abraham S. Moses Olena R. Taratula Hyelim Lee Fangzhou Luo Tanner Grenz Tetiana Korzun Anna St Lorenz Fahad Y. Sabei Shay Bracha Adam W. G. Alani Ov D. Slayden Oleh Taratula 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(18)
Endometriosis is a painful disorder where endometrium‐like tissue forms lesions outside of the uterine cavity. Intraoperative identification and removal of these lesions are difficult. This study presents a nanoplatform that concurrently delineates and ablates endometriosis tissues using real‐time near‐infrared (NIR) fluorescence and photothermal therapy (PTT). The nanoplatform consists of a dye, silicon naphthalocyanine (SiNc), capable of both NIR fluorescence imaging and PTT, and a polymeric nanoparticle as a SiNc carrier to endometriosis tissue following systemic administration. To achieve high contrast during fluorescence imaging of endometriotic lesions, nanoparticles are constructed to be non‐fluorescent prior to internalization by endometriosis cells. In vitro studies confirm that these nanoparticles activate the fluorescence signal following internalization in macaque endometrial stromal cells and ablate them by increasing cellular temperature to 53 °C upon interaction with NIR light. To demonstrate in vivo efficiency of the nanoparticles, biopsies of endometrium and endometriosis from rhesus macaques are transplanted into immunodeficient mice. Imaging with the intraoperative Fluobeam 800 system reveals that 24 h following intravenous injection, nanoparticles efficiently accumulate in, and demarcate, endometriotic grafts with fluorescence. Finally, the nanoparticles increase the temperature of endometriotic grafts up to 47 °C upon exposure to NIR light, completely eradicating them after a single treatment. 相似文献
27.
Yaroslav Shpotyuk Pavlo Demchenko Zdenka Bujňáková Peter Baláž Catherine Boussard-Pledel Bruno Bureau Oleh Shpotyuk 《Journal of the American Ceramic Society》2020,103(3):1631-1646
Effect of high-energy mechanical milling on glassy AsxSe100 − x (5 ≤ x ≤ 75) is recognized with X-ray powder diffraction analysis applied to their diffuse halos ascribed to intermediate—and extended-range structural ordering, which are revealed respectively in the first sharp diffraction peak (FSDP) and principal diffraction peak (PDP). Straightforward interpretation of the results is developed within modified microcrystalline approach, treating diffuse halos as superposition of broadened Bragg-diffraction reflexes from remnants of inter-planar correlations, supplemented by inter-atomic Ehrenfest-diffraction reflexes from most prominent inter-atomic and inter-molecular correlations between cage-like molecules (such As4Se4 and/or As4Se3). Milling is shown to be ineffective in glassy arsenoselenides near Se (x < 20), while causing increase in the FSDP width for glasses with 20 ≤ x ≤ 40 due to destroyed inter-planar ordering. Remnants of cage-like molecules in over-stoichiometric As-rich AsxSe100 − x glasses (40 ≤ x ≤ 75) disappear under milling, promoting formation of higher polymerized structural network. This milling-driven reamorphization results in a drastic increase in the FSDP position and fragmentation impact on the correlation length of the FSDP-responsible entities. Breakdown in intermediate-range ordering in these glasses is accompanied by changes in their extended-range ordering revealed in high-angular shift and broadening of the PDP. This effect is concomitant with the disappearance of distant inter-atomic correlations between quasi-crystalline planes in the milled arsenoselenide glasses at a cost of prolonged correlations dominating in their extended-range ordering. 相似文献
28.
Dong Bok Lee Min Jung Kim Li Chen Sang Hwan Bak Oleh Yaskiv Iryna Pohrelyuk Viktor Fedirko 《Metals and Materials International》2011,17(3):471-477
Ti-6Al-4V alloys were nitrided through gas nitriding at 950 °C for 3 h in deoxygenated, atmospheric nitrogen gas. During nitriding,
nitrogen reacted and diffused into the alloys to form Ti2N and a meager amount of TiN in a Ti-N compound layer with a thickness of 20 μm to 25 μm. An α-Ti(N) diffusion layer with
a thickness of 40 μm to 80 μm formed below this layer. A small amount of Al was dissolved at the top of the Ti-N compound
layer because of the strong interaction of nitrogen with Ti and Al. Nitriding resulted in the dissolution of interstitial
nitrogen and the formation of nitrides. Oxidation of the nitrided Ti-6Al-4V alloys initially resulted in the formation of
a Ti-N-O layer, which later oxidized to TiO2. Above 800 °C, the nitrided alloys oxidized rapidly, accompanied by microcracking of the TiO2 surface layer. 相似文献
29.
Oleh Shpotyuk Peter Baláž Zdenka Bujňáková Adam Ingram Pavlo Demchenko Yaroslav Shpotyuk 《Journal of Materials Science》2018,53(19):13464-13476
The amorphization is studied in mechanically activated β-As4S4 using high-energy ball milling in a dry mode with 100–600 min?1 rotational speeds, employing complementary methods of X-ray powder diffraction (XRPD) related to the first sharp diffraction peak, positron annihilation lifetime (PAL) spectroscopy, and ab initio quantum-chemical simulation within cation-interlinking network cluster approach (CINCA). The amorphous substance appeared under milling in addition to nanostructurized β-As4S4 shows character XRPD halos parameterized as extrapolation of the FSDPs, proper to near-stoichiometric amorphous As–S alloys. The structural network of amorphized arsenicals is assumed as built of randomly packed multifold cycle-type entities proper to As4S4 network. The depressing and time-enhancing tendency in the PAL spectrum peak is direct indicative of milling-driven amorphization, associated with free-volume evolution of interrelated positron- and Ps-trapping sites. At lower speeds (200–500 min?1), these changes include Ps-to-positron trapping conversion, but they attain an opposite direction at higher speed (600 min?1) due to consolidation of β-As4S4 crystallites. In respect of CINCA modeling, the effect of high-energy milling is identified as destruction–polymerization action on monomer cage-type As4S4 molecules and existing amorphous phase, transforming them to amorphous network of triple-broken As4S4 derivatives. These findings testify in a favor of “shell” kinetic model of solid-state amorphization, the amorphous phase continuously generated under speed-increased milling being identified as compositionally authentic to arsenic monosulfide, different in medium range ordering from stoichiometric As2S3. 相似文献
30.
A three-dimensional wavelet-based algorithm for nonlinear registration of an elastic body model of the brain is developed. Surfaces of external and internal anatomic brain structures are used to guide alignment. The deformation field is represented with a multiresolution wavelet expansion and is modeled by the partial differential equations of linear elasticity. A progressive estimation of the registration parameters and the usage of an adaptive distance map reduce algorithm complexity, thereby providing computational flexibility that allows mapping of large, high resolution datasets. The performance of the algorithm was evaluated on rat brains. The wavelet-based registration method yielded a twofold improvement over affine registration. 相似文献