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951.
Al-doped ZnO (AZO, ZnO:Al2O3 = 98:2 wt%) films are deposited on different substrates by an RF magnetron sputtering and subsequently annealed at three different conditions to investigate the microstructural, electrical, and optical properties. X-ray diffraction and scanning electron microscope results show that all the samples are polycrystalline and the samples rapid-thermal-annealed at 900 °C in an N2 ambient contain larger grains compared to the furnace-annealed samples. It is shown that the sample deposited at room temperature on the sapphire gives a resistivity of 5.57 × 10−4 Ω cm when furnace-annealed at 500 °C in a mixture of N2:H2 (9:1). It is also shown that the Hall mobility vs. carrier concentration (μ-n) relation is divided into two groups, depending on the annealing conditions, namely, either rapid-thermal annealing or furnace annealing. The relations are described in terms of either grain boundary scattering or ionized impurity scattering mechanism. In addition, the samples produce fairly high transmittance of 91-96.99% across the wavelength region of 400-1100 nm. The optical bandgaps of the samples increase with increasing carrier concentration. 相似文献
952.
We studied the initial‐stage mechanism of the electrophilic addition reaction of ethene with HCl by examining the interactions between ethene and HCl on water‐ice and frozen molecular films at temperatures of 80–140 K. Cs+ reactive ion scattering (RIS) and low‐energy sputtering (LES) techniques were used to probe the reaction intermediates that were kinetically trapped on the surface, in conjunction with temperature‐programmed desorption (TPD) mass spectrometry to monitor the desorbing species. The reaction initially produced the π complex of HCl and ethene at temperatures below about 93 K and an “ethyl cationic species” at temperatures below about 100 K. The ethyl cationic species was formed via direct proton transfer from the HCl molecule to ethene with the assistance of water solvation, rather than via the interaction of hydronium ions and ethene. At high temperatures, this species dissociated into ethene and hydronium and chloride ions. The reaction did not, however, complete the final transition state on the ice surface to produce ethyl chloride. The observation gives evidence that the electrophilic addition reaction of ethene occurs through an ethyl‐like intermediate with an ionic character. 相似文献
953.
The total synthesis of psymberin was achieved employing a readily available chiral epoxide to prepare two of the three subunits in the natural product. The key reaction was a highly stereoselective organocatalytic oxa-conjugate addition reaction of α,β-unsaturated ketone catalyzed by primary diamine for the synthesis of the 2,6-trans-tetrahydropyran embedded in psymberin. 相似文献
954.
In this study, some possible biomedical applications of a pH-sensitive and amphiphilic copolymer as a pH sensor and protein delivery system are reported. PAE-g-PEG was used as a pH-sensitive polymer that can exhibit a sharp pH-dependent transition. Various fluorescent dyes including pyrene and RITC can be used to label the pH-sensitive polymer PAE-g-PEG, which was evaluated for protein encapsulation. pH-sensing was possible by observing excimer formation of the labeled pyrene via pH-dependent expansion of the polymeric chain. Also, it was confirmed that FITC-BSA could be entrapped in RITC-labeled pH-sensitive micelles of PAE-g-PEG by FRET. As a result, PAE-g-PEG can be a pH sensor and carrier for protein delivery. 相似文献
955.
Particle focusing in planar geometries is essentially required in order to develop cost-effective lab-on-a-chips, such as cell counting and point-of-care (POC) devices. In this study, a novel method for sheathless particle focusing, called "Elasto-Inertial Particle Focusing", was demonstrated in a straight microchannel. The particles were notably aligned along the centerline of the straight channel under a pressure-driven flow without any additional external force or apparatus after the addition of an elasticity enhancer: PEO (poly(ethylene oxide)) (~O(100) ppm). As theoretically predicted (elasticity number: El≈O(100)), multiple equilibrium positions (centerline and corners) were observed for the viscoelastic flow without inertia, whereas three-dimensional particle focusing only occurred when neither the elasticity nor the inertia was negligible. Therefore, the three-dimensional particle focusing mechanism was attributed to the synergetic combination of the elasticity and the inertia (elasticity number: El≈O(1-10)). Furthermore, from the size dependence of the elastic force upon particles, we demonstrated that a mixture of 5.9 and 2.4 μm particles was separated at the exit of the channel in viscoelastic flows. We expect that this method can contribute to develop the miniaturized flow cytometry and microdevices for cell and particle manipulation. 相似文献
956.
Thickness‐dependent electroforming behavior of ultra‐thin Ta2O5 resistance switching layer
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Tae Hyung Park Seul Ji Song Hae Jin Kim Soo Gil Kim Suock Chung Beom Yong Kim Kee Jeung Lee Kyung Min Kim Byung Joon Choi Cheol Seong Hwang 《固体物理学:研究快报》2015,9(6):362-365
Electroforming behaviours of Ta2O5 resistance switching memory cell with a diameter of 28 nm and different thickness (0.5–2.0 nm) of Ta2O5 layer have been examined. The devices showed a constant forming electric field of 0.54 V/nm regardless of Ta2O5 thickness. The electroforming with negative bias to top TiN electrode was ascribed to electric field‐ driven migration of oxygen vacancies, originally residing near the bottom interface, toward the top electrode interface and formation of conducting filaments. The estimated electroforming energy (0.094–0.14 eV) was favourably compared with the hopping energy of electrons from the VO site to a nearby Ta site. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
957.
Dr. Da‐Young Sung Dr. Jayavant L. Gunjakar Dr. Tae Woo Kim Dr. In Young Kim Yu Ri Lee Prof. Seong‐Ju Hwang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(22):7109-7117
A new prompt room temperature synthetic route to 2D nanostructured metal oxide–graphene‐hybrid electrode materials can be developed by the application of colloidal reduced graphene oxide (RGO) nanosheets as an efficient reaction accelerator for the synthesis of δ‐MnO2 2D nanoplates. Whereas the synthesis of the 2D nanostructured δ‐MnO2 at room temperature requires treating divalent manganese compounds with persulfate ions for at least 24 h, the addition of RGO nanosheet causes a dramatic shortening of synthesis time to 1 h, underscoring its effectiveness for the promotion of the formation of 2D nanostructured metal oxide. To the best of our knowledge, this is the first example of the accelerated synthesis of 2D nanostructured hybrid material induced by the RGO nanosheets. The observed acceleration of nanoplate formation upon the addition of RGO nanosheets is attributable to the enhancement of the oxidizing power of persulfate ions, the increase of the solubility of precursor MnCO3, and the promoted crystal growth of δ‐MnO2 2D nanoplates. The resulting hybridization between RGO nanosheets and δ‐MnO2 nanoplates is quite powerful not only in increasing the surface area of manganese oxide nanoplate but also in enhancing its electrochemical activity. Of prime importance is that the present δ‐MnO2–RGO nanocomposites show much superior electrode performance over most of 2D nanostructured manganate systems including a similar porous assembly of RGO and layered MnO2 nanosheets. This result underscores that the present RGO‐assisted solution‐based synthesis can provide a prompt and scalable method to produce nanostructured hybrid electrode materials. 相似文献
958.
Heung‐Man Lee Man Sik Park Il Ho Park Seung Hoon Lee Seong Keon Lee Kyu‐Sung Kim Hyuk Choi 《Photochemistry and photobiology》2013,89(3):751-757
Although allergic rhinitis is not life threatening, it significantly influences the quality of a patient's life. This study is intended to evaluate the safety and efficacy of phototherapy with low‐level energy of a 650 nm laser irradiation system in perennial allergic rhinitis patients. This clinical trial was an open‐label, single‐center study with 42 perennial allergic rhinitis subjects. Following laser irradiation in the nasal cavity with a laser irradiation system, the efficacy at weeks 1 through 4 was determined. The symptoms were scored with four parameters (nasal obstruction, rhinorrhea, sneezing and itching) before and after illumination of the laser, and the total score was recorded. A survey of Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) was conducted by patients before and after treatment. Following treatment, significant improvement in the clinical symptoms of nasal obstruction (P < 0.001), rhinorrhea (P = 0.005), sneezing (P = 0.001) and itching (P = 0.003) was reported by 68% of perennial allergic rhinitis patients. The overall RQLQ scores significantly improved by 45% from the baseline with the treatment after 4 weeks. These results indicate that phototherapy is an effective modality for treating perennial allergic rhinitis and is another option in the steroid‐free management of immune‐mediated mucosal diseases. 相似文献
959.
Marino MJ Hsiao E Chen Y Eryilmaz OL Erdemir A Kim SH 《Langmuir : the ACS journal of surfaces and colloids》2011,27(20):12702-12708
The friction behavior of diamond-like carbon (DLC) is very sensitive to the test environment. For hydrogen-rich DLC tested in dry argon and hydrogen, there was always an induction period, so-called "run-in" period, during which the friction coefficient was high and gradually decreased before DLC showed an ultralow friction coefficient (less than 0.01) behavior. Regardless of friction coefficients and hydrogen contents, small amounts of wear were observed in dry argon, hydrogen, oxygen, and humid argon environments. Surprisingly, there were no wear or rubbing scar on DLC surfaces tested in n-pentanol vapor conditions, although the friction coefficient was relatively high among the five test environments. Ex situ X-ray photoelectron and near-edge X-ray absorption fine-structure spectroscopy analyses failed to reveal any differences in chemical composition attributable to the environment dependence of DLC friction and wear. The failure of getting chemical information of oxygenated surface species from the ex situ analysis was found to be due to facile oxidation of the DLC surface upon exposure to air. The removal or wear of this surface oxide layer is responsible for the run-in behavior of DLC. It was discovered that the alcohol vapor can also prevent the oxidized DLC surface from wear in humid air conditions. 相似文献
960.
Park H Jeon JY Kim SY Jeong DG Ryu SE 《Journal of computer-aided molecular design》2011,25(5):469-475
Mitogen-activated protein kinase phosphatase-1 (MKP-1) has proved to be an attractive target for the development of therapeutics
for the treatment of cancer. We report the first example for a successful application of the structure-based virtual screening
to identify the novel inhibitors of MKP-1. It is shown that the efficiency of virtual screening can be enhanced significantly
by the incorporation of a new solvation energy term in the scoring function. The newly found inhibitors have desirable physicochemical
properties as a drug candidate and reveal a moderate potency with IC50 values ranging from 20 to 50 μM. Therefore, they deserve a consideration for further development by structure–activity relationship
studies to optimize the inhibitory activities. Structural features relevant to the stabilization of the inhibitors in the
active site of MKP-1 are discussed in detail. 相似文献