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101.
Im Sang-Jin Shim Jae-Hyuk Kim Joo-Yeon Baek Hyeon-Man 《Applied magnetic resonance》2020,51(3):255-276
Applied Magnetic Resonance - Total cerebral volume increases very rapidly in childhood, peaking in early teenage years then declining in adolescence. However, most studies quantified only one or... 相似文献
102.
Han Chung-Hun Hong Jeong Woo Im Hee-Jung 《Journal of Radioanalytical and Nuclear Chemistry》2021,328(2):563-568
Journal of Radioanalytical and Nuclear Chemistry - The efficiency transfer procedure from a geometry where a volume source was placed directly on the endcap of a germanium detector to three... 相似文献
103.
ABSTRACTThe potential-energy surfaces of the amino radical (NH2) with IO reaction have been studied at the CCSD(T)/cc-pVTZ//MP2/6-311++G(d,p) level. Two kinds of pathways are revealed, namely H-abstraction and addition/elimination. Rice–Ramsperger–Kassel–Marcus theory and transition state theory are employed to calculate the overall and individual rate constants over a wide range of temperatures and pressures. It is predicted that, at atmospheric pressure with N2 as bath gas, the formation of P1 (HI?+?HNO) is the dominant pathways at 200–700?K, while the direct H-abstraction leading to P3 (3NH?+?HOI) takes over the reaction at a temperature above 700?K. At the high-pressure limit, IM1 [IONH2] formed by collisional stabilisation is dominant at 200–700?K; the direct H-abstraction resulting in P3 (3NH?+?HOI) plays an important role at higher temperatures. However, the total rate constants are independence on the pressure; however, the individual rate constants are sensitive to pressure. The atmospheric lifetime of NH2 in IO is around one week. TD-DFT computations imply that IM1 [IONH2], IM1A [IONH2′], IM2 [IN(H2)O], IM3 [OINH2], IM4 [HOINH], tra-IM5 [tra-HON(H)I] and cis-IM5 [cis-HON(H)I] will photolyze under the sunlight. 相似文献
104.
The singlet and triplet potential energy surfaces for the CH2BrO2??+??Cl reaction have been researched theoretically. All of the probable reaction routes were investigated by using B3LYP and G3(MP2) models. Addition/elimination and SN2 displacement exist on the singlet potential energy surfaces (PES), and the foremost approach process of CH2BrO2??+??Cl is generating IM1 (CH2BrOOCl) with no barrier, followed by the O-O bond breaking accompanied by an H-migrate resulting in the most abundant product P1 (CHBrO?+?HClO). One direct H-abstraction and three SN2 displacement reaction pathways exist on the triplet PES, and direct H-abstraction is the foremost pathway. RRKM-TST theory was employed to predict product distribution of the CH2BrO2??+??Cl reaction. At atmospheric pressure, the production of P1 (CHBrO?+?HClO) by addition/elimination dominants the reaction at T?≤?800?K, while the direct H-abstraction takes over the reaction at T?>?800?K. The total rate constants are insensitive to pressure, and the branching rate constants are just the opposite. The lifetime of CH2BrO2? in the presence of ?Cl was predicted to 3.2?d. Moreover, time-dependent density functional theory (TDDFT) calculations suggest that IM1 (CH2BrOOCl), IM2 (CH2BrOClO) and IM3 (CH2(OBr)OCl) will photolyze under the sunlight. 相似文献
105.
Reflection high-energy electron diffraction, atomic force microscopy, transmission electron microscopy, and double-crystal X-ray curves showed that high-quality InAs quantum dot (QD) arrays inserted into GaAs barriers were embedded in an Al0.3Ga0.7As/GaAs heterostructure. The temperature-dependent photoluminescence (PL) spectra of the InAs/GaAs QDs showed that the exciton peak corresponding interband transition from the ground electronic subband to the ground heavy-hole subband (E1-HH1) was dominantly observed and that the peak position and the full width at half maximum corresponding to the interband transitions of the PL spectrum were dependent on the temperature. The activation energy of the electrons confined in the InAs/GaAs QDs was 115 meV. The electronic subband energy and the energy wave function of the Al0.3Ga0.7As/GaAs heterostructures were calculated by using a self-consistent method. The electronic subband energies in the InAs/GaAs QDs were calculated by using a three-dimensional spatial plane wave method, and the value of the calculated (E1-HH1) transition in the InAs/GaAs QDs was in reasonable agreement with that obtained from the PL measurement. 相似文献
106.
Effect of Si in reactively sputtered Ti-Si-N films on structure and diffusion barrier performance 总被引:2,自引:0,他引:2
X. Sun E. Kolawa S. Im C. Garland M.-A. Nicolet 《Applied Physics A: Materials Science & Processing》1997,65(1):43-45
34 Si23N43 (b3) and Ti35Si13N52 (c3), are synthesized by reactively sputtering a Ti5Si3 or a Ti3Si target, respectively. The silicon-lean film (c3) has a columnar structure closely resembling that of TiN. As a diffusion
barrier between a shallow Si n+p junction diode and a Cu overlayer, this material is effective up to 700 °C for 30 min annealing in vacuum, a performance
similar to that for TiN. The silicon-rich (b3) film contains nanocrystals of TiN, randomly oriented and embedded in an amorphous
matrix. A film of (b3) maintains the stability of the same diode structure up to 850 °C for 30 min in vacuum. This film (b3)
is clearly superior to TiN or to (c3). Similar experiments performed with Al instead of Cu overlayers highlight the importance
of the thermodynamic stability of a barrier layer and demonstrate convincingly that for stable barriers the microstructure
is a parameter that directly determines the barrier performance.
Received: 18 November 1996/Accepted: 22 January 1997 相似文献
107.
We have evaluated thermal stability and aging property of a blue color-emitting phosphor, CaAl2Si2O8:Eu2+ (CAS:Eu2+), synthesized by conventional solid-state reaction method. When both CAS:Eu2+ and BaMgAl10O19:Eu2+ (BAM) were baked in air at 500 °C for 20 min, the decrease of photoluminescence (PL) intensity of CAS:Eu2+ was lower than that of BAM. The aging property of CAS:Eu2+ was also better than that of BAM. Due to its rigid structure and unlimited framework of silicon-oxygen and aluminum-oxygen around Eu2+ ions, Eu2+ ions were protected from outer oxidizing atmosphere and plasma discharge. After analysis of aging property and thermal stability, the differences of these thermal stability and aging property of CAS:Eu2+ from those of BAM were ascribed to its crystal structure which plays a role of a shield for Eu2+ ions against oxidation atmosphere and Xe ion bombardment. 相似文献
108.
Approximate fibrations form a useful class of maps. By definition fibrators provide instant detection of maps in this class, and PL fibrators do the same in the PL category. This paper formalizes a natural concept of partial asphericity and establishes fibrator properties of certain partially aspherical closed manifolds. One consequence is that any connected sum of aspherical PL manifolds with residually finite fundamental groups is a codimension-(2n−2) PL fibrator. 相似文献
109.
Hee-Jung Im Carl Willis Suree Saengkerdsub Rajev Makote Michelle D. Pawel Sheng Dai 《Journal of Sol-Gel Science and Technology》2004,32(1-3):117-123
Solid-state scintillating materials were synthesized by the co-doping of sol–gel components with neutron absorbers [6Li and 10B], organic fluorescence sensitizers such as salicylic acid and 2,5-diphenyloxazole (PPO) and activator 1,4-bis-2-(5-phenyloxazolyl)-benzene (POPOP). The room-temperature sol–gel process through the addition of organic polymers is the key to the successful entrapment of the organic sensitizers and activator in inorganic matrixes. These transparent or translucent sol–gel scintillators were evaluated for alpha radiation and neutron detections. 相似文献
110.
Oh C Chung SC Shin SI Kim YC Im SS Oh SG 《Journal of colloid and interface science》2002,254(1):79-86
The distribution of macropores in silica particles prepared by the hydrolysis and condensation of TEOS in a hexane/water/decyl alcohol (O(1)/W/O(2)) multiple emulsion was investigated. To stabilize the emulsion structure, hydroxypropyl cellulose (HPC) was added into the O(2) phase and polyethylene glycol (PEG) was added into the water phase. Without HPC, the particles have an irregular shape and hardly have particulate forms. As the concentration of HPC increases, the shape of particles becomes more and more spherical and the size decreases. The size of silica particles was varied from 5 to 1 microm as the concentration of HPC increased from 0.5 to 0.7 wt%. The number and size of the macropores in silica particles were affected by PEG polymer concentration. With the variation in the concentration of PEG, macropores in silica particles were located at the surface of or inside the particles. At high concentrations of PEG, the macropores in particles were located inside the particles, but at low concentrations of PEG the macropores were located at the surfaces of particles. Interestingly, the particles of dimpled surfaces were formed when the molar ratio of water to TEOS (R(w)) was 4.0 and the concentrations of PEG and HPC were 2.0 and 0.7 wt% respectively. The surface areas of dimpled silica particles and completely spherical particles, measured by the BET method, were 409 and 433 m(2)/g respectively. 相似文献