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991.
Seong Wook Lim Hoi-Gu Jang Hye-In Sim Chae-Ho Shin Jong-Ho Kim Gon Seo 《Journal of Porous Materials》2014,21(5):797-809
Dandelion-type silica spheres with a dendrimer-like porous structure were prepared by adding pore modifiers into aqueous synthetic mixtures of tetraethylorthosilicate (TEOS), hexadecyltrimethylammonium bromide (CTAB), ammonium hydroxide, and acetone. The formation of silica spheres and their porous characteristics were investigated using various techniques, including electron microscopy, nitrogen adsorption, and thermogravimetric analysis. Benzyl acetate (BENA) was very effective in the formation of a dendrimer-like porous structure. However, the composition of TEOS, CTAB, acetone, and BENA strongly influenced the size and shape of the silica spheres and their porous structure. The synthetic mixture of 1 TEOS: 0.22 CTAB: 1.9 BENA: 0.32 NH4OH: 36 acetone: 236 H2O produced dandelion-type silica spheres with diameters of ~300 nm. The phosphazenium hydroxide (PzOH) catalyst supported on the dandelion-type silica spheres prepared by adding BENA showed high catalytic performance in the transesterification of soybean oil with methanol due to its high feasibility for rapid access of large triglyceride molecules into the basic PzOH moieties incorporated in the pores. 相似文献
992.
Predicted Ligands for the Human Urotensin‐II G Protein‐Coupled Receptor with Some Experimental Validation 下载免费PDF全文
Dr. Soo‐Kyung Kim Prof. William A. Goddard III Dr. Kyu Yang Yi Dr. Byung Ho Lee Chae Jo Lim Prof. Bartosz Trzaskowski 《ChemMedChem》2014,9(8):1732-1743
Human Urotensin‐II (U‐II) is the most potent mammalian vasoconstrictor known. 1 Thus, a U‐II antagonist would be of therapeutic value in a number of cardiovascular disorders. 2 Here, we describe our work on the prediction of the structure of the human U‐II receptor (hUT2R) using GEnSeMBLE (GPCR Ensemble of Structures in Membrane BiLayer Environment) complete sampling Monte Carlo method. With the validation of our predicted structures, we designed a series of new potential antagonists predicted to bind more strongly than known ligands. Next, we carried out R‐group screening to suggest a new ligand predicted to bind with 7 kcal mol?1 better energy than 1‐{2‐[4‐(2‐bromobenzyl)‐4‐hydroxypiperidin‐1‐yl]ethyl}‐3‐(thieno[3,2‐b]pyridin‐7‐yl)urea, the designed antagonist predicted to have the highest affinity for the receptor. Some of these predictions were tested experimentally, validating the computational results. Using the pharmacophore generated from the predicted structure for hUT2R bound to ACT‐058362, we carried out virtual screening based on this binding site. The most potent hit compounds identified contained 2‐(phenoxymethyl)‐1,3,4‐thiadiazole core, with the best derivative exhibiting an IC50 value of 0.581 μM against hUT2R when tested in vitro. Our efforts identified a new scaffold as a potential new lead structure for the development of novel hUT2R antagonists, and the computational methods used could find more general applicability to other GPCRs. 相似文献
993.
Jae Woong Han Sangiliyandi Gurunathan Jae-Kyo Jeong Yun-Jung Choi Deug-Nam Kwon Jin-Ki Park Jin-Hoi Kim 《Nanoscale research letters》2014,9(1):459
The goal of the present study was to investigate the toxicity of biologically prepared small size of silver nanoparticles in human lung epithelial adenocarcinoma cells A549. Herein, we describe a facile method for the synthesis of silver nanoparticles by treating the supernatant from a culture of Escherichia coli with silver nitrate. The formation of silver nanoparticles was characterized using various analytical techniques. The results from UV-visible (UV-vis) spectroscopy and X-ray diffraction analysis show a characteristic strong resonance centered at 420 nm and a single crystalline nature, respectively. Fourier transform infrared spectroscopy confirmed the possible bio-molecules responsible for the reduction of silver from silver nitrate into nanoparticles. The particle size analyzer and transmission electron microscopy results suggest that silver nanoparticles are spherical in shape with an average diameter of 15 nm. The results derived from in vitro studies showed a concentration-dependent decrease in cell viability when A549 cells were exposed to silver nanoparticles. This decrease in cell viability corresponded to increased leakage of lactate dehydrogenase (LDH), increased intracellular reactive oxygen species generation (ROS), and decreased mitochondrial transmembrane potential (MTP). Furthermore, uptake and intracellular localization of silver nanoparticles were observed and were accompanied by accumulation of autophagosomes and autolysosomes in A549 cells. The results indicate that silver nanoparticles play a significant role in apoptosis. Interestingly, biologically synthesized silver nanoparticles showed more potent cytotoxicity at the concentrations tested compared to that shown by chemically synthesized silver nanoparticles. Therefore, our results demonstrated that human lung epithelial A549 cells could provide a valuable model to assess the cytotoxicity of silver nanoparticles. 相似文献
994.
Allaeddine Djouama Myoung-Seob Lim Fatiha Youcef Ettoumi 《Wireless Personal Communications》2014,79(3):2291-2304
In this paper, minimum mean square error-support vector regression (MMSE-SVR) is proposed, which is shown to be adequate for the estimation of the long term evolution (LTE) uplink channel with nonlinear features. MMSE-SVR was applied to estimate real channel environments such as the vehicular A channels defined by the International Telecommunication Union (ITU). The simulation results show that the proposed method has a better performance than the least squares support vector machine (LS-SVM) and the standard MMSE with linear and spline interpolation. 相似文献
995.
Thanh Binh Mai Thi Nga Tran Md. Rafiqul Islam Jong Myung Park Kwon Taek Lim 《Journal of Materials Science》2014,49(4):1519-1526
A facile method has been developed for the synthesis of core–shell nanostructure poly(N-isopropylacrylamide) grafted on silica nanoparticles (SiO2 NPs) by using the combination of ARGET ATRP and thiol-ene click chemistry. The covalent attachment of the thermo-responsive polymer was achieved by taking advantage of the fast, robust, and high efficient thiol-ene click reaction as demonstrated by FT-IR and XPS. The ARGET ATRP provides the good conversion of the monomer in a well-controlled manner as indicated by the narrow value of PDI (1.21). The grafting amount of the polymer on SiO2 NPs was found to be ca. 18 % as determined by TGA technique. TEM images of the encapsulated SiO2 NPs suggested that the SiO2 NPs core was covered by the soft polymer layer. Interestingly, dynamic light scattering analysis revealed that the as-synthesized nanocomposites exhibited the thermo-responsive behavior with the transition temperature around 31–33 °C. 相似文献
996.
Yujeong Kim Chang Eun Song Ara Cho Jungwoon Kim Yoonho Eom Jongho Ahn Sang-Jin Moon Eunhee Lim 《Materials Chemistry and Physics》2014
Two π-conjugated small molecules based on diketopyrrolopyrrole (DPP), DPP4T and DPP2F2T, were synthesized using the Suzuki coupling reaction. DPP4T and DPP2F2T contained furan and thiophene, respectively, next to a DPP core. Organic photovoltaic cells (OPVs) were fabricated using two DPP-based oligothiophenes as donors. DPP4T showed higher power conversion efficiency (PCE) (1.44%) than DPP2F2T (0.85%). The short-circuit current (JSC) of DPP4T (4.38 mA cm−2) was nearly twice that of DPP2F2T (2.49 mA cm−2). The improved photovoltaic properties of DPP4T could be explained by the optical properties and the film morphology. 相似文献
997.
998.
Fatigue-induced damage is often progressive and gradual in nature. Fatigue is often deteriorated by corrosion in ageing structures, creating maintenance problems, and even causing catastrophic failure. This ushers the development of structural health monitoring (SHM) and nondestructive evaluation (NDE) systems. Recent advent of smart materials applicable in SHM alleviates the shortcomings of the conventional techniques. Autonomous, real-time, remote monitoring becomes possible with the use of smart piezoelectric transducers. For instance, the electro-mechanical impedance (EMI) technique, employing piezoelectric transducers as collocated actuators and sensors, is known for its ability in damage detection and characterization. This article presents a series of lab-scale experimental tests and analysis to investigate the feasibility of fatigue crack detection and characterization employing the EMI technique. This study extends the work by Lim and Soh [1] to incorporate the phases involving crack initiation and critical crack. It is suggested that the EMI technique is effective in characterizing fatigue induced cracking, even in its incipient stage. Micro-crack invisible to the naked eyes can be detected by the technique especially when employing the higher frequency range of 100–200 kHz. A quick and handy qualitative-based critical crack identification method is also suggested by visually inspecting the admittance frequency spectrum. 相似文献
999.
Semiconductors: 25th Anniversary Article: Materials for High‐Performance Biodegradable Semiconductor Devices (Adv. Mater. 13/2014) 下载免费PDF全文
1000.
Nanogenerators: Highly‐Efficient,Flexible Piezoelectric PZT Thin Film Nanogenerator on Plastic Substrates (Adv. Mater. 16/2014) 下载免费PDF全文