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131.
132.
JH Kim YW Noh MB Heo MY Cho YT Lim 《Angewandte Chemie (International ed. in English)》2012,51(38):9670-9673
A winning combination: Multifunctional hybrid nanoconjugates (HNCs) based on polymer nanoparticles containing quantum dots (QDs) conjugated with CpG oligonucleotides (as a ligand for TLR9) and STAT3 siRNAs (to suppress the immune response) have been synthesized. These HNCs were shown to synergistically enhance the antitumor immune response in dendritic cells and in tumor-bearing mice. 相似文献
133.
We investigated the hydrogen bonding structures and proton transfer for the hydration complexes of alizarin (Az) produced in a supersonic jet using fluorescence excitation (FE), dispersed laser induced fluorescence (LIF), visible-visible hole burning (HB), and fluorescence detected infrared (FDIR) spectroscopy. The FDIR spectrum of bare Az with two O-H groups exhibits two vibrational bands at 3092 and 3579 cm(-1), which, respectively, correspond to the stretching vibration of O1-H1 that forms a strong intramolecular hydrogen bond with the C9=O9 carbonyl group and the stretching vibration of O2-H2 that is weakly hydrogen-bonded to O1-H1. For the 1:1 hydration complex Az(H(2)O)(1), we identified three conformers. In the most stable conformer, the water molecule forms hydrogen bonds with the O1-H1 and O2-H2 groups of Az as a proton donor and proton acceptor, respectively. In the other conformers, the water binds to the C10=O10 group in two nearly isoenergetic configurations. In contrast to the sharp vibronic peaks in the FE spectra of Az and Az(H(2)O)(1), only broad, structureless absorption was observed for Az(H(2)O)(n) (n≥ 2), indicating a facile decay process, possibly due to proton transfer in the electronic excited state. The FDIR spectrum with the wavelength of the probe laser fixed at the broad band exhibited a broad vibrational band near the O2-H2 stretching vibration frequency of the most stable conformer of Az(H(2)O)(1). With the help of theoretical calculations, we suggest that the broad vibrational band may represent the occurrence of proton transfer by tunnelling in the electronic ground state of Az(H(2)O)(n) (n≥ 2) upon excitation of the O2-H2 vibration. 相似文献
134.
Enhanced mid-IR luminescence of Tm3+ ions in Ga2S3 nanocrystals embedded chalcohalide glass ceramics
Shixun Dai Changgui Lin Feifei Chen Xianghua Zhang Chao Liu Kai Xu Jong Heo Xiang Shen Xunsi Wang 《Journal of Non》2011,357(11-13):2302-2305
Chalcohalide glass with a composition of 65GeS2–25Ga2S3–10CsI (in mol%) doped with 0.6 wt% Tm3+ ions was prepared by conventional melt–quench method. By heat treating the precursor glass at 20 °C above its glass transition temperature Tg for different durations, IR transparent glass ceramics were obtained. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that Ga2S3 crystallites were precipitated after heat treatment and their grain sizes were in nano-scale and increased with the elongation of heat treated time. Mid-IR luminescence properties of the glass and transparent glass ceramic samples were investigated. The emissions at 2.3 and 3.8 μm corresponding to optical transitions of 3H4 → 3H5 and 3H5 → 3F4 of Tm3+ ions were significantly enhanced by the presence of Ga2S3 nanocrystals and reached a maximum after 8 hours treatment. 相似文献
135.
Sang-Jun Choi Ki-Hong Kim Woo-Young Yang Hyung-Ik Lee Sung Heo Gyeong-Su Park Hyun-Joon Shin Hyeongwoo Yu Minho Kim Soohaeng Cho 《Applied Physics A: Materials Science & Processing》2013,112(4):807-815
We investigated the resistive switching behaviors of the metal–copper oxide–metal devices with the enhanced capability in terms of high speed and multi-bit operation. From the analysis of the normal and extended resistive switching behaviors, the voltage-induced resistive changes were modeled and the resistive switching polarity was explained. Also, we proposed and fabricated a dual vacancy-type device structure with an extended resistive switching behavior and demonstrated a high-speed implemental 2-bit multi-bit operation by controlling specifically switch-on voltage pulses. 相似文献
136.
We perform density functional calculations to investigate structural and dynamical properties of crystalline polyvinylidene difluoride (PVDF) associated with the transition from α to β phase. We examine the change of the conformational energy and the corresponding structure of each phase depending on the lattice parameters of the orthorhombic crystalline structure. From this information, we construct the path that connects the point where the α phase is most stable to the point where the β phase is most stable, and identify the sub‐ region in the lattice parameter space where α and β phases have the same energy. In this sub‐region, we locate the point which gives the lowest conformation energy for both α and β phases, and examine the behaviour of the lowest energy profile and corresponding change of intermediate structures as the conformation of the PVDF chain transforms from α phase to β phase. Finally we perform ab‐initio molecular dynamics simulations and analyse the characteristic dynamics associated with transition from α to β phase. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
137.
Precipitation of PbS quantum dots (QDs) in silicate glasses controlled by Ag+ ion diffusion was investigated. Ag+ ions penetrated ~ 0.5 μm into the glass when the glass was immersed in the AgNO3 solution at 80 °C. Ag nano-particles (NPs) and PbS QDs were formed after heat-treatment at temperatures of 420–460 °C for 10 h. PbS QDs in Ag+-diffused regions photoluminesced at longer wavelengths than did those in Ag+-free regions. This indicates that PbS QDs thus formed in regions containing Ag NPs were larger than those in Ag+-free regions and this size difference was confirmed from the transmission electron microscope images. PbS QDs can grow at temperature as low as 420 °C in Ag+-diffused regions and this implies that PbS QDs form preferentially using Ag NPs as nucleating agents. 相似文献
138.
Synchronized bursts are a very common feature in biological neural networks, and they play an important role in various brain functions and neurological diseases. This Letter investigates "recurrent synchronized bursts" induced by a single pulse stimulation in cultured networks of rat cortical neurons. We look at how the precision in their arrival times can be modified by a noble time-delayed stimulation protocol, which we term as "Δt training." The emergence of recurrent bursts and the change of the precision in their arrival times can be explained by the stochastic resonance of a damped, subthreshold, neural oscillation. 相似文献
139.
C.M. Shin J.H. Heo C.R. Kim J.H. Chang W.J. Lee J.L. Zhao 《Applied Surface Science》2009,255(20):8501-8505
In this study, the effects of the annealing duration of a zinc oxide (ZnO) buffer layer on structural and optical properties of ZnO rods grown by a hydrothermal process are discussed. A ZnO buffer layer was deposited on p-type Si (1 1 1) substrates by the metal organic chemical vapor deposition (MOCVD) method. After that, ZnO rods were grown on the ZnO-buffer/Si (1 1 1) substrate by a hydrothermal process. In order to determine the optimum annealing duration of the buffer layer for the growth of ZnO rods, durations ranging from 0.5 to 30 min were tried. The morphology and crystal structure of the ZnO/ZnO-buffer/Si (1 1 1) were measured by field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). The optical properties were investigated by photoluminescence (PL) measurement. 相似文献
140.
G. H. Kim U. Kang D. Heo V. E. Yashin A. V. Kulik E. G. Sall’ S. A. Chizhov 《Optics and Spectroscopy》2010,108(5):819-823
A femtosecond laser based on an Yb:KYW crystal with direct longitudinal pumping by a high-power semiconductor injection laser
with a fiber output is described. Femtosecond pulses were generated in the self-longitudinal-mode-locking operating condition
due to the use of a semiconductor saturable absorber. The average power of the oscillator was as high as 3.5 W at a central
wavelength of 1035 nm, the pulse length and pulse repetition rate being 200 fs and 85.5 MHz, respectively. The product of
the pulse length and the radiation spectrum width was 1.3 times higher than the theoretical limit for the pulse shape described
by the function sech2. The designed master oscillator can be also used as a stand-alone source of femtosecond radiation pulses for material microprocessing
and primary source for femtosecond laser amplification systems. 相似文献