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21.
Irradiation with approximately 10 keV x rays or medium-energy electrons destroys long-range order of Ir spin dimers in CuIr2S4 while preserving the dimers locally. We find that as the order is destroyed, a new type of incommensurate structural correlations appears. This represents an intriguing example of order from disorder phenomenon, in which a previously unknown incommensurate order appears in the radiation-induced disordered state. These results suggest that two competing instabilities, one of which can be suppressed by radiation, are present in the system. Otherwise unrealized structural or electronic states can, therefore, be revealed in correlated systems by x-ray or electron irradiation. 相似文献
22.
Seal K Genov DA Sarychev AK Noh H Shalaev VM Ying ZC Zhang X Cao H 《Physical review letters》2006,97(20):206103
Near-field intensity statistics in semicontinuous silver films over a wide range of surface coverage are investigated using near-field scanning optical microscopy. The variance of intensity fluctuations and the high-order moments of intensity enhancement exhibit local minima at the percolation threshold. This reduction in local field fluctuations results from resonant excitation of delocalized surface plasmon modes. By probing the modification of the critical indices for high-order moments of intensity enhancement caused by the delocalized states, we provide the first experimental evidence for the coexistence of localized and delocalized surface plasmon modes in percolating metal films. 相似文献
23.
Jongho Shin Kyungsik Jang Ki-Soo Lim Ik-Bu Sohn Young-Chul Noh Jongmin Lee 《Applied Physics A: Materials Science & Processing》2008,93(4):1015-927
We report the spectroscopic properties of femtosecond laser-irradiated sodium-alumino-borate glass doped with silver and gold
ions. We precipitated gold and silver nanoparticles by laser irradiation and annealing at 400°C for 30 min. The irradiation
and annealing treatment produced different absorption and emission characteristics in Au3+ doped and Au3+, Ag+ codoped glasses, and the possible mechanisms of the observed results are discussed. The size of the nanoparticles was estimated
by TEM and absorption band analysis. 相似文献
24.
Design of highly active and stable electrocatalyst is a major objective in a fuel cell. The special situation imposed to the electrocatalyst such as one of the most sluggish catalysis of oxygen reduction reaction, inherent structural instability of dispersed nanoparticle, harsh electrochemical conditions of electric potential and nonzero pH aqueous solution requires unique attention in the design. Considering that various attempts have been made for the purpose, high-speed but rigorous formalisms to evaluate the performance of candidates are crucial.This review article briefly introduces recently developed first-principles computational methodologies mainly applied to catalytic activity and electrochemical stability of electrocatalysts in proton exchange membrane fuel cells. Innovative design principles deduced from the outcomes are clearly discussed. 相似文献
25.
Optical Review - We present analytical solutions for the subsidiary maxima in multiple slit interference up to eleven slits. For the number of slits N, there exist $$N-2$$ subsidiary maxima between... 相似文献
26.
Dr. Ying Wang Ara Cho Dr. Guangri Jia Prof. Xiaoqiang Cui Junhyeop Shin Prof. Inho Nam Kyung-Jong Noh Byoung Joon Park Rui Huang Prof. Jeong Woo Han 《Angewandte Chemie (International ed. in English)》2023,62(15):e202300119
Single-atom nanozymes (SAzymes) are promising in next-generation nanozymes, nevertheless, how to rationally modulate the microenvironment of SAzymes with controllable multi-enzyme properties is still challenging. Herein, we systematically investigate the relationship between atomic configuration and multi-enzymatic performances. The constructed MnSA−N3-coordinated SAzymes (MnSA−N3−C) exhibits much more remarkable oxidase-, peroxidase-, and glutathione oxidase-like activities than that of MnSA−N4−C. Based on experimental and theoretical results, these multi-enzyme-like behaviors are highly dependent on the coordination number of single atomic Mn sites by local charge polarization. As a consequence, a series of colorimetric biosensing platforms based on MnSA−N3−C SAzymes is successfully built for specific recognition of biological molecules. These findings provide atomic-level insight into the microenvironment of nanozymes, promoting rational design of other demanding biocatalysts. 相似文献
27.
Su‐Kyung Lee Kyong‐Soon Shin Dr. Dong‐Youn Noh Prof. Dr. Olivier Jeannin Dr. Frédéric Barrière Dr. Jean‐François Bergamini Dr. Marc Fourmigué Dr. 《化学:亚洲杂志》2010,5(1):169-176
The redox‐active and chelating diphosphine, 3,4‐dimethyl‐3′,4′‐bis(diphenylphosphino)‐tetrathiafulvalene, denoted as P2 , is engaged in a series of platinum complexes, [(P2)Pt(dithiolene)], with different dithiolate ligands, such as 1,2‐benzenedithiolate (bdt), 1,3‐dithiole‐2‐thione‐4,5‐dithiolate (dmit), and 5,6‐dihydro‐1,4‐dithiin‐2,3‐dithiolate (dddt). The complexes are structurally characterized by X‐ray diffraction, together with a model compound derived from bis(diphenylphosphino)ethane, namely, [(dppe)Pt(dddt)] . Four successive reversible electron‐transfer processes are found for the [(P2)Pt(dddt)] complex, associated with the two covalently linked but electronically uncoupled electrophores, that is, the TTF core and the platinum dithiolene moiety. The assignments of the different redox processes to either one or the other electrophore is made thanks to the electrochemical properties of the model compound [(dppe)Pt(dddt)] lacking the TTF redox core, and with the help of theoretical calculations (DFT) to understand the nature and energy of the frontier orbitals of the [(P2)Pt(dithiolene)] complexes in their different oxidation states. The first oxidation of the highly electron‐rich [(P2)Pt(dddt)] complex can be unambiguously assigned to the redox process affecting the Pt(dddt) moiety rather than the TTF core, a rare example in the coordination chemistry of tetrathiafulvalenes acting as ligands. 相似文献
28.
Chi Won Kim Jungmin Ahn Sung Min Kim Tae Hwan Noh Ok-Sang Jung 《Transition Metal Chemistry》2011,36(5):545-551
Type studies on competitive polyatomic anion versus acetonitrile coordination in the self-assembly of a series of [Ag2(X)
m
(bip)(NCCH3)
n
](X)2−m
(X− = NO3
−, CF3SO3
−, ClO4
−, BF4
−, and PF6
−; m = 0, 2; n = 0, 2, 4; bip = 1,4-bis(2-isonicotinoyloxyethyl)piperazine) were carried out. Each bip spacer acts as an N4 tetradentate ligand and is linked to four silver(I) centers through two pyridine and two piperazine moieties, producing a
double strand consisting of two 20-membered ring units. The coordinating environment around the silver(I) center is subtly
determined by the competition of the polyatomic anions with acetonitrile, that is, by the Ag···NCCH3 versus Ag···X interactions. The coordinating ability of acetonitrile is inversely proportional to the order of the coordination
ability of the Hoffmeister series of polyatomic anions, NO3
− ≫ CF3SO3
− > ClO4
− > BF4
− ≫ PF6
−. 相似文献
29.
Hemalatha Murugaiah Chow Lun Teh Kai Chew Loh Ahmad Ramli Mohamad Yahya Nur Asshifa Md Noh Noor Hana Hanif Abu Bakar Daruliza Kernain Rokiah Hashim Yazmin Bustami 《Molecules (Basel, Switzerland)》2021,26(21)
Here, we report the extracellular biosynthesis of silver nanoparticles (AgNPs) and determination of their antibacterial and anticancer properties. We also explore the efficacy of bioAgNPs incorporated in cellulose nanocrystals (CNCs) and alginate (Alg) for the formation of an antibacterial hydrogel film. Streptomyces sp. PBD-311B was used for the biosynthesis of AgNPs. The synthesized bioAgNPs were characterized using UV-Vis spectroscopy, TEM, XRD, and FTIR analysis. Then, the bioAgNPs’ antibacterial and anticancer properties were determined using TEMA and cytotoxicity analysis. To form the antibacterial hydrogel film, bioAgNPs were mixed with a CNC and Alg solution and further characterized using FTIR analysis and a disc diffusion test. The average size of the synthesized bioAgNPs is around 69 ± 2 nm with a spherical shape. XRD analysis confirmed the formation of silver nanocrystals. FTIR analysis showed the presence of protein capping at the bioAgNP surface and could be attributed to the extracellular protein binding to bioAgNPs. The MIC value of bioAgNPs against P. aeruginosa USM-AR2 and MRSA was 6.25 mg/mL and 3.13 mg/mL, respectively. In addition, the bioAgNPs displayed cytotoxicity effects against cancer cells (DBTRG-0.5MG and MCF-7) and showed minimal effects against normal cells (SVG-p12 and MCF-10A), conferring selective toxicity. Interestingly, the bioAgNPs still exhibited inhibition activity when incorporated into CNC/Alg, which implies that the hydrogel film has antibacterial properties. It was also found that bioAgNP-CNC/Alg displayed a minimal or slow release of bioAgNPs owing to the intermolecular interaction and the hydrogel’s properties. Overall, bioAgNP-CNC/Alg is a promising antibacterial hydrogel film that showed inhibition against the pathogenic bacteria P. aeruginosa and MRSA and its application can be further evaluated for the inhibition of cancer cells. It showed benefits for surgical resection of a tumor to avoid post-operative wound infection and tumor recurrence at the surgical site. 相似文献
30.
Tae Young Jang Ku Bong Chung Hye Ri Eom Dong Kyun Noh In Kyu Song Jongheop Yi Sung-Hyeon Baeck 《Research on Chemical Intermediates》2011,37(9):1275-1282
Catalytic hydrogenation of lactic acid to propylene glycol was performed over various metals (Ag, Co, Cu, Ni, Pt, and Ru) supported on silica prepared by an incipient wetness impregnation method. The loading amount of each metal was 5 wt%. Crystallinity of the synthesized catalysts was investigated by X-ray diffraction (XRD), and the BET method was utilized to examine the surface area. Pore volume and pore size of catalysts were determined using BJH analysis of the N2 adsorption isotherm. Particle sizes of various metals were determined from transmission electron microscopy (TEM) images. The catalytic activity was found to be strongly dependent on the supported metal. Among catalysts tested, Ru/SiO2 showed the highest propylene glycol yield. The yield of propylene glycol increased with pressure, and the highest yield was achieved at 130 °C. 相似文献