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21.
Sukmoon Huh 《Annali di Matematica Pura ed Applicata》2011,190(2):195-208
We investigate the jumping conics of stable vector bundles E of rank 2 on a smooth quadric surface Q with the first Chern class c1 = OQ(-1,-1){c_1= \mathcal{O}_Q(-1,-1)} with respect to the ample line bundle OQ(1,1){\mathcal {O}_Q(1,1)} . We show that the set of jumping conics of E is a hypersurface of degree c
2(E) − 1 in
\mathbb P3*{\mathbb {P}_3^{*}} . Using these hypersurfaces, we describe moduli spaces of stable vector bundles of rank 2 on Q in the cases of lower c
2(E). 相似文献
22.
Seong Huh Young Jun Park Alan. J. Lough Moo‐Jin Jun 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):416-417
The title compound, [RuH(C6H8BN4)(C21H21P)2(CO)], possesses two trans‐disposed tri‐p‐tolylphosphines in axial positions and the remaining ligands in equatorial positions. The overall geometry of the RuII ion is a distorted octahedral structure. The P—Ru—P axis deviates from linearity by about 13°. This distortion arises mainly from the steric congestion between the bulky phosphine moieties and the tetrahedral dihydrobis(pyrazol‐1‐yl)borate ligands. 相似文献
23.
Xiaofeng Wu Jong Min An Jizhen Shang Eugene Huh Sujie Qi Eunhye Lee Haidong Li Gyoungmi Kim Huimin Ma Myung Sook Oh Dokyoung Kim Juyoung Yoon 《Chemical science》2020,11(41):11285
Acetylcholinesterase (AChE) is an extremely critical hydrolase tightly associated with neurological diseases. Currently, developing specific substrates for imaging AChE activity still remains a great challenge due to the interference from butyrylcholinesterase (BChE) and carboxylesterase (CE). Herein, we propose an approach to designing specific substrates for AChE detection by combining dimethylcarbamate choline with a self-immolative scaffold. The representative P10 can effectively eliminate the interference from CE and BChE. The high specificity of P10 has been proved via imaging AChE activity in cells. Moreover, P10 can also be used to successfully map AChE activity in different regions of a normal mouse brain, which may provide important data for AChE evaluation in clinical studies. Such a rational and effective approach can also provide a solid basis for designing probes with different properties to study AChE in biosystems and another way to design specific substrates for other enzymes.In this work, a new approach was developed for designing the representative P10 with high selectivity and sensitivity for imaging AChE activity in the cells and normal mouse brain. 相似文献
24.
Sung-Jae Chung Seung-Moo Huh Jung-Il Jin 《Journal of polymer science. Part A, Polymer chemistry》1996,34(6):1105-1112
A series of new wholly aromatic polyesters was synthesized by melt polycondensation of 1-phenyl-2,6-naphthalenedicarboxylic acid (PNDA) and diacetates of various aromatic diols. The aromatic diols studied are hydroquinone (HQ), methylhydroquinone (MHQ), phenylhydroquinone (PHQ), (α-phenylisopropyl)hydroquinone (PIHQ), 2,6-naphthalenediol (2,6-ND), 1,4-naphthalenediol (1,4-ND), and 4,4′-biphenol (BP). These polyesters were characterized for their crystallinity, glass transition temperature (Tg), melting temperature (Tm), liquid crystallinity, and thermal stability. In general, crystallinity of the polyesters are very low and the Tg values of the polyesters range from 150 to 172°C depending on the structure of aromatic diols. All of the polymers formed nematic phases above their Tm or Tg. The polyesters derived from PHQ and PIHQ are soluble in chlorinated hydrocarbon solvents. The initial decomposition temperatures of the polyesters are above 400°C under N2 atmosphere. © 1996 John Wiley & Sons, Inc. 相似文献
25.
Huang SJ Huh S Lo PS Liu SH Lin VS Liu SB 《Physical chemistry chemical physics : PCCP》2005,7(16):3080-3087
An extensive study has been made on a series of multifunctional mesoporous silica materials, prepared by introducing two different organoalkoxysilanes, namely 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (AEPTMS) and 3-cyanopropyltriethoxysilane (CPTES) during the base-catalyzed condensation of tetraethoxysilane (TEOS), using the variable-temperature (VT) hyperpolarized (HP) 129Xe NMR technique. VT HP-129Xe NMR chemical shift measurements of adsorbed xenon revealed that surface properties as well as functionality of these AEP/CP-functionalized microparticles (MP) could be controlled by varying the AEPTMS/CPTES ratio in the starting solution during synthesis. Additional chemical shift contribution due to Xe-moiety interactions was observed for monofunctional AEP-MP and CP-MP as well as for bifunctional AEP/CP-MP samples. In particular, unlike CP-MP that has a shorter organic backbone on the silica surface, the amino groups in the AEP chain tends to interact with the silanol groups on the silica surface causing backbone bending and hence formation of secondary pores in AEP-MP, as indicated by additional shoulder peak at lower field in the room-temperature 129Xe NMR spectrum. The exchange processes of xenon in different adsorption regions were also verified by 2D EXSY HP-129Xe NMR spectroscopy. It is also found that subsequent removal of functional moieties by calcination treatment tends to result in a more severe surface roughness on the pore walls in bifunctional samples compared to monofunctional ones. The effect of hydrophobicity/hydrophilicity of the organoalkoxysilanes on the formation, pore structure and surface property of these functionalized mesoporous silica materials are also discussed. 相似文献
26.
27.
Lewis basic DABCO-functionalized 3D-like metal-organic framework, Zn-MOF, catalyzes nitroaldol (Henry) reaction of 4-nitrobenzaldehyde with nitroalkanes in a size-dependent manner. Small nitroalkanes give rise to higher conversion than larger ones. This MOF-based heterogeneous catalyst is very robust and can be recycled several times without losing its activity. 相似文献
28.
Kim K Choi SH Jeon J Lee H Huh JO Yoo J Kim JT Lee CH Lee YS Churchill DG 《Inorganic chemistry》2011,50(12):5351-5360
One 8-phenyl and two 8-mesityl-substituted "scorpionate"-like BODIPY-type species of the formula [3,4,4-tris(5-R-(2-thienyl))-8-(2,4,6-R'-phenyl)-4-bora-3a,4a-diaza-s-indacene (R = H, R' = H, 3a; R, = H, R' = Me, 2a; R, = Me, R' = Me, 2b)] have been synthesized and fully characterized. Importantly, differences in their solution (MeCN) optical Cu(2+) and Hg(2+) probing capacity via SSS-chelation were investigated. Compounds 2a-3a were prepared from the requisite 8-substituted BODIPY complexes. They were characterized first by complete (1)H, (11)B and (13)C NMR spectroscopic assignments (CD(3)Cl or CD(3)C(O)CD(3)); the molecular structures of 2a and 3a were determined by X-ray crystallography. Compounds 2a-3a were studied by UV-vis and fluorescence spectroscopy [Φ(F) = 0.27 ± 0.013 (2a); 0.024 ± 0.0016 (2b); 0.0034 ± 0.00047 (3a)]. Importantly, low [Cu(2+)] with 3a (<3.0 × 10(-5) M) gave rise to an increase of fluorescence intensity (off-on; 6.3-fold), whereas with 2a it decreased (on-off). When [Hg(2+)] (<3.0 × 10(-5) M) was added to 2b, the λ(em,max) value increased (off-on; 3.2-fold), and for 2a, it decreased (on-off). The association constant (K(a)) for Hg(2+)·2a was determined to be 3120 ± 307 M(-1). An approximate stoichiometric 1:1 binding determined by Job plot analysis is in line with successful DFT modeling of SSS-Cu(2+) binding for this system type. (1)H NMR spectroscopy also revealed tentative sets of product complex peaks. These simple differences caused by formal ligand Me-group incorporation are the first for any related fluorophores, to the best of our knowledge. 相似文献
29.
Hong JH Hwang YK Hong JY Kim HJ Kim SJ Won YS Huh S 《Chemical communications (Cambridge, England)》2011,47(24):6963-6965
To simply reduce HAuCl(4) using 2-thiophenemethanol in an aqueous solution at room temperature, a novel metallic Au nanostructure with a high SERS activity was obtained. Flat sheet-like Au nanoleaves possessing many nanogap hotspots bound with a large percentage of high-index facets were obtained. 相似文献
30.
Trace detection and physicochemical characterization of protein aggregates have a large impact in understanding and diagnosing many diseases, such as ageing-related neurodegeneration and systemic amyloidosis, for which the formation of protein aggregates is one of the pathological hallmarks. Here we demonstrate an innovative label-free method for detecting and characterizing small amounts of early stage protein aggregates using a Raman active nanofluidic device. Sub-micrometre channels formed by a novel elastomeric collapse technique enable the separation and concentration of matured protein aggregates from small protein molecules. The Raman enhancement by gold nanoparticle clusters fixed below a micro/nanofluidic junction allows characterization of intrinsic properties of protein aggregates at concentration levels (~fM) much lower than can be done with traditional analytical tools. With our device we show for the first time the concentration dependence of protein aggregation over these low concentration ranges. We expect that our method could facilitate definitive diagnosis and possible therapeutics of diseases at early stages. 相似文献