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991.
We propose an ultrasmall plasmonic cavity consisting of a high-index/low-index dielectric nanorod covered with silver. Full three-dimensional subwavelength confinement of the surface-plasmon polaritons was achieved at the high-index dielectric-silver interface without propagating to the low-index dielectric-silver interface. The numerical simulations showed that the plasmonic mode excited in this cavity has a deep subwavelength mode volume of 0.0038(λ/2n)(3) and a quality factor of 1500 at 40 K, and consequently a large Purcell factor of ~2×10(5). Therefore, this plasmonic cavity is expected to be useful for the demonstration of high-efficiency single photon sources or low-threshold lasers in an ultracompact nanophotonic circuit. 相似文献
992.
An aqueous vesicular system that is switchable by electric potential without addition of any chemical redox agents into the solution is demonstrated using redox-responsive self-assembly of an amphiphilic rod-coil molecule consisting of a tetraaniline and a poly(ethylene glycol) block. The vesicle membrane is split by an oxidizing voltage into smaller pucklike micelles that can reassemble to form vesicles upon exposure to a reducing voltage. The switching mechanism is explained by the packing behavior of the tetraaniline units constituting the membrane core, which depends on their oxidation states. 相似文献
993.
Lee JH Zhang Q Jo S Chai SC Oh M Im W Lu H Lim HS 《Journal of the American Chemical Society》2011,133(4):676-679
There is considerable interest in developing non-peptidic, small-molecule α-helix mimetics to disrupt α-helix-mediated protein?protein interactions. Herein, we report the design of a novel pyrrolopyrimidine-based scaffold for such α-helix mimetics with increased conformational rigidity. We also developed a facile solid-phase synthetic route that is amenable to divergent synthesis of a large library. Using a fluorescence polarization-based assay, we identified cell-permeable, dual MDMX/MDM2 inhibitors, demonstrating that the designed molecules can act as α-helix mimetics. 相似文献
994.
Tuan Anh PhamByung Choon Choi Kwon Taek LimYeon Tae Jeong 《Applied Surface Science》2011,257(8):3350-3357
Amino—functionalized gold nanoparticles with a diameter of around 5 nm were immobilized onto the surface of graphene oxide sheets (GOS) by covalent bonding through a simple amidation reaction. Pristine graphite was firstly oxidized and exfoliated to obtain GOS, which further were acylated with thionyl chloride to give acyl chloride bound GOS. Gold nanoparticles (AuNPs) were functionalized using 4-aminothiophenol in a single-phase system to introduce amino groups on their surface through the well-developed Au-S chemistry. Subsequently, amino groups of AuNPs were reacted with acyl chloride groups of GOS to form a novel hybrid material containing GOS and AuNPs. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy were used to study the changes in surface functionalities and demonstrate the successful immobilization of AuNPs on GOS surface. High resolution transmission electron microscopy (HR-TEM), field emission scanning electronic microscopy (FE-SEM), and atomic force microscopy (AFM) were employed to investigate the morphologies of prepared AuNPs and their distribution onto the GOS surface. Thermogravimetric analysis (TGA) was used to characterize the thermal stability of the samples on heating. 相似文献
995.
Regan G. Wilks Gap Soo Chang Kyung Hwan Kim Dong Hoon Choi Alexander Moewes 《Journal of Electron Spectroscopy and Related Phenomena》2011,184(7):355-359
Angle resolved near-edge absorption fine structure measurements of the C 1s edge of a film of the star-shaped molecule 4(HPBT) show a high degree of order, with the molecules maintaining a largely planar geometry in an upright configuration. X-ray excited optical luminescence measurements showed a dependence of the luminescence spectrum on the excitation energy, with (0–0), (0–1), and (0–2) vibrational modes being clearly visible when exciting off-resonance; the appearance of these features under off-resonance is attributed to a scattering process that is quenched when the excitation approaches a core absorption resonance. The HOMO–LUMO gap is estimated from the luminescence measurements (2.28 eV), and this value is confirmed by the comparison of the C 1s absorption and C Kα emission spectra. 相似文献
996.
Muhammed een Jong Min Oh Zeynep
zdemir Saliha Ebru Büyüktuncel Mehtap Uysal Mohamed A. Abdelgawad Arafa Musa Nicola Gambacorta Orazio Nicolotti Bijo Mathew Hoon Kim 《Molecules (Basel, Switzerland)》2020,25(22)
Twelve pyridazinones (T1–T12) containing the (2-fluorophenyl) piperazine moiety were designed, synthesized, and evaluated for monoamine oxidase (MAO) -A and -B inhibitory activities. T6 was found to be the most potent MAO-B inhibitor with an IC50 value of 0.013 µM, followed by T3 (IC50 = 0.039 µM). Inhibitory potency for MAO-B was more enhanced by meta bromo substitution (T6) than by para bromo substitution (T7). For para substitution, inhibitory potencies for MAO-B were as follows: -Cl (T3) > -N(CH3)2 (T12) > -OCH3 (T9) > Br (T7) > F (T5) > -CH3 (T11) > -H (T1). T6 and T3 efficiently inhibited MAO-A with IC50 values of 1.57 and 4.19 µM and had the highest selectivity indices (SIs) for MAO-B (120.8 and 107.4, respectively). T3 and T6 were found to be reversible and competitive inhibitors of MAO-B with Ki values of 0.014 and 0.0071, respectively. Moreover, T6 was less toxic to healthy fibroblast cells (L929) than T3. Molecular docking simulations with MAO binding sites returned higher docking scores for T6 and T3 with MAO-B than with MAO-A. These results suggest that T3 and T6 are selective, reversible, and competitive inhibitors of MAO-B and should be considered lead candidates for the treatment of neurodegenerative disorders like Alzheimer’s disease. 相似文献
997.
998.
Yumeng Liu Dong Tian Akash N. Biswas Zhenhua Xie Sooyeon Hwang Ji Hoon Lee Hong Meng Jingguang G. Chen 《Angewandte Chemie (International ed. in English)》2020,59(28):11345-11348
The electrochemical carbon dioxide reduction reaction (CO2RR) to produce synthesis gas (syngas) with tunable CO/H2 ratios has been studied by supporting Pd catalysts on transition metal nitride (TMN) substrates. Combining experimental measurements and density functional theory (DFT) calculations, Pd‐modified niobium nitride (Pd/NbN) is found to generate much higher CO and H2 partial current densities and greater CO Faradaic efficiency than Pd‐modified vanadium nitride (Pd/VN) and commercial Pd/C catalysts. In‐situ X‐ray diffraction identifies the formation of PdH in Pd/NbN and Pd/C under CO2RR conditions, whereas the Pd in Pd/VN is not fully transformed into the active PdH phase. DFT calculations show that the stabilized *HOCO and weakened *CO intermediates on PdH/NbN are critical to achieving higher CO2RR activity. This work suggests that NbN is a promising substrate to modify Pd, resulting in an enhanced electrochemical conversion of CO2 to syngas with a potential reduction in precious metal loading. 相似文献
999.
Hee‐Jeong Cha Se‐Yeun Hwang Da‐Som Lee Akula Ravi Kumar Yong‐Uk Kwon Moritz Voß Eva Schuiten Uwe T. Bornscheuer Frank Hollmann Deok‐Kun Oh Jin‐Byung Park 《Angewandte Chemie (International ed. in English)》2020,59(18):7024-7028
Long‐chain aliphatic amines such as (S,Z)‐heptadec‐9‐en‐7‐amine and 9‐aminoheptadecane were synthesized from ricinoleic acid and oleic acid, respectively, by whole‐cell cascade reactions using the combination of an alcohol dehydrogenase (ADH) from Micrococcus luteus, an engineered amine transaminase from Vibrio fluvialis (Vf‐ATA), and a photoactivated decarboxylase from Chlorella variabilis NC64A (Cv‐FAP) in a one‐pot process. In addition, long chain aliphatic esters such as 10‐(heptanoyloxy)dec‐8‐ene and octylnonanoate were prepared from ricinoleic acid and oleic acid, respectively, by using the combination of the ADH, a Baeyer–Villiger monooxygenase variant from Pseudomonas putida KT2440, and the Cv‐FAP. The target compounds were produced at rates of up to 37 U g?1 dry cells with conversions up to 90 %. Therefore, this study contributes to the preparation of industrially relevant long‐chain aliphatic chiral amines and esters from renewable fatty acid resources. 相似文献
1000.
Won‐Woo Park Kyung Min Lee Byeong Sung Lee Young Jae Kim Se Hun Joo Sang Kyu Kwak Tae Hyeon Yoo Oh‐Hoon Kwon 《Angewandte Chemie (International ed. in English)》2020,59(18):7089-7096
Here, we propose an experimental methodology based on femtosecond‐resolved fluorescence spectroscopy to measure the hydrogen (H)‐bond free energy of water at protein surfaces under isothermal conditions. A demonstration was conducted by installing a non‐canonical isostere of tryptophan (7‐azatryptophan) at the surface of a coiled‐coil protein to exploit the photoinduced proton transfer of its chromophoric moiety, 7‐azaindole. The H‐bond free energy of this biological water was evaluated by comparing the rates of proton transfer, sensitive to the hydration environment, at the protein surface and in bulk water, and it was found to be higher than that of bulk water by 0.4 kcal mol?1. The free‐energy difference is dominated by the entropic cost in the H‐bond network among water molecules at the hydrophilic and charged protein surface. Our study opens a door to accessing the energetics and dynamics of local biological water to give insight into its roles in protein structure and function. 相似文献