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971.
A planar and instantaneous visualization study of high-speed gas jets and their airblast sprays was performed to qualitatively examine the different atomization performances of different gas nozzles. For the visualization of high-speed gas jets (with no liquid injected), Nd:YAG pulsed laser sheets imaged the clustered vapor molecules in the Rayleigh range (d?λ), condensed from the natural humidity during the isentropic gas expansion through a nozzle. This method visualized both underexpanded sonic gas jets from a converging nozzle (SN-Type) and overexpanded supersonic gas jets from a converging-diverging nozzle (CD-Type). When liquid is cross-injected, the same laser sheet images the spray droplets of relatively large sizes (d?λ). The present visualization results show that the SN-Type nozzle develops a wider spray than the CD-Type nozzle, quite probably because the SN-Type nozzle has a wider gas jet (in the absence of liquid) than the CD-Type. Also, the wider spray of the SN-Type nozzle lowers the probability of droplet coalescence and generates finer sprays compared to the CD-Type nozzle. These visualization results qualitatively agree with the previous quantitative finding of the different atomization characteristics of the two types of nozzles (Park et al. 1996). 相似文献
972.
A De A Mitra A Ray SR Banerjee M Sengupta A Chatterjee S Kailas HS Patel MG Betigiri SK Dutta 《Pramana》1999,53(3):549-552
In this paper, we report our measurements of back-angle oxygen and carbon particle yields from 16O+89Y, 12C+93Nb reactions forming the same compound nucleus 105Ag at the same excitation energy and spin distribution. We find anomalously large oxygen yield and entrance channel dependence
at high excitation energies from 16O+89Y reaction implying formation of a dinuclear orbiting complex. Possible connection between nuclear orbiting and fast fission
is also discussed. 相似文献
973.
974.
二过碘酸合铜(Ⅲ)钾引发丙烯腈在聚丙烯酰胺上接枝共聚合反应的研究 总被引:1,自引:0,他引:1
本文以二过碘酸合铜(Ⅲ)钾为氧化剂,聚丙烯酰胺(PAAM)自身为还原剂组成的氧化还原引发体系,在PAAM上引发丙烯腈接枝共聚合反应,获得了高接枝效率和高接枝百分比的产物,由红外光谱、扫描电镜及X射线衍射分析对接枝反应进行了表征,测定了各种条件对接枝参数的影响,并对引发机理进行了探讨。 相似文献
975.
Son H. Nguyen Duan Berek Ignc Capek Oscar Chiantore 《Journal of polymer science. Part A, Polymer chemistry》2000,38(12):2284-2291
Products of the radical dispersion copolymerization of methacryloyl‐terminated poly(ethylene oxide) (PEO) macromonomer and styrene were separated and characterized by size exclusion chromatography (SEC), full adsorption‐desorption (FAD)/SEC coupling and eluent gradient liquid adsorption chromatography (LAC). In dimethylformamide, which is a good solvent for PEO side chains but a poor solvent for polystyrene (PS), amphiphilic PS‐graft‐PEO copolymers formed aggregates, which were very stable at room temperature even upon substantial dilution. The aggregates disappeared at high temperature or in tetrahydrofuran (THF), which is a good solvent for both homopolymers and for PS‐graft‐PEO. FAD/SEC procedure allowed separation of homo‐PS from graft‐copolymer and determination of both its amount and molar mass. Effective molar mass of graft‐copolymer was estimated directly from the SEC calibration curve determined with PS standards. Presence of larger amount of the homo‐PS in the final graft‐copolymer products was also confirmed with LAC measurements. The results indicate that there are at least two or maybe three polymerization loci; namely the continuous phase, the particle surface layer and the particle core. The graft copolymers are produced mainly in the continuous phase while PS or copolymer rich in styrene units is formed mostly in the core of monomer‐swollen particles. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2284–2291, 2000 相似文献
976.
Intae Son Chi Hyeong Cho Gitae Moon Chunho Kim Eunbi Lee Eun Hyoung Bae 《Molecular Crystals and Liquid Crystals》2019,687(1):68-75
AbstractA vertically-aligned liquid crystal (LC) device with fast-switching LC molecules and excellent electro-optical properties is proposed. The proposed method employs a mixture of a polyimide to achieve the desired vertical alignment, and a mesogenic photocrosslinker to obtain the fast LC response. More specifically, the photocrosslinkers were photopolymerized by UV irradiation under an electric field to pre-tilt the LC molecules. In addition, upon increasing the number of functional groups in the photocrosslinker, faster switching properties were exhibited due to enhanced pre-tilting. Following UV irradiation, the proposed system also exhibited stable homeotropic alignment properties similar to those of conventional polyimides. 相似文献
977.
Younghun Kim Heechan Kim Dr. Jung Bae Son Dr. Michael Filatov Prof. Dr. Cheol Ho Choi Prof. Dr. Nam Ki Lee Prof. Dr. Dongwhan Lee 《Angewandte Chemie (International ed. in English)》2023,62(20):e202302107
Molecular emitters simultaneously generating light at different wavelengths have wide applications. With a small molecule, however, it is challenging to realize two independent radiative pathways. We invented the first examples of dual-emissive single-benzene fluorophores (SBFs). Two emissive tautomers are generated by synthetic modulation of the hydrogen bond acidity, which opens up pathways for excited-state proton transfer. White light is produced by a delicate balance between the energy and intensity of the emission from each tautomer. We show that the excited-state antiaromaticity of the benzene core itself dictates the proton movements driving the tautomer equilibrium. Using this simple benzene platform, a fluorinated SBF was synthesized with a record high solubility in perfluorocarbon solvents. White light-emitting devices and multicolor imaging of perfluorocarbon nanodroplets in live cells demonstrate the practical utility of these molecules. 相似文献
978.
Dr. Dahham Kim Hayoung Son Prof. Dr. Seung Bum Park 《Angewandte Chemie (International ed. in English)》2023,62(52):e202310665
Various fluorogenic probes utilizing tetrazine (Tz) as a fluorescence quencher and bioorthogonal reaction partner have been extensively studied over the past few decades. Herein, we synthesized a series of boron-dipyrromethene (BODIPY)-Tz probes using monochromophoric design strategy for bioorthogonal cellular imaging. The BODIPY-Tz probes exhibited excellent bicyclo[6.1.0]nonyne (BCN)-selective fluorogenicity with three- to four-digit-fold enhancements in fluorescence over a wide range of emission wavelengths, including the far-red region. Furthermore, we demonstrated the applicability of BODIPY-Tz probes in bioorthogonal fluorescence imaging of cellular organelles without washing steps. We also elucidated the aromatized pyridazine moiety as the origin of BCN-selective fluorogenic behavior. Additionally, we discovered that the fluorescence of the trans-cyclooctene (TCO) adducts was quenched in aqueous media via photoinduced electron transfer (PeT) process. Interestingly, we observed a distinctive recovery of the initially quenched fluorescence of BODIPY-Tz-TCO upon exposure to hydrophobic media, accompanied by a significant bathochromic shift of its emission wavelength relative to that exhibited by the corresponding BODIPY-Tz-BCN. Leveraging this finding, for the first time, we achieved dual-color bioorthogonal cellular imaging with a single BODIPY-Tz probe. 相似文献
979.
Vinh Son Nguyen Myrna H. Matus Daniel J. Grant Minh Tho Nguyen David A. Dixon 《ChemInform》2007,38(48):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. 相似文献
980.
Dr. Soumen Dutta Akshay Gurumoorthi Shinbi Lee Sun Woo Jang Dr. Nitee Kumari Yu-Rim Hong Prof. Dr. Wonyong Choi Prof. Dr. Chang Yun Son Prof. Dr. In Su Lee 《Angewandte Chemie (International ed. in English)》2023,62(28):e202303890
Herein, by choosing few-nm-thin two-dimensional (2D) nanocrystals of MOF-5 containing in-planner square lattices as a modular platform, a crystal lattice-guided wet-chemical etching has been rationally accomplished. As a result, two attractive pore patterns carrying Euclidean curvatures; precisely, plus(+)-shaped and fractal-patterned pores via ⟨100⟩ and ⟨110⟩ directional etching, respectively, are regulated in contrast to habitually formed spherical-shaped random etches on MOF surface. In agreement with the theoretical calculations, a diffusion-limited etching process has been optimized to devise high-yield of size-tunable fractal-pores on the MOF surface that tenders for a compatibly high payload of catalytic ReI-complexes using the existing large edge area once modified into a free amine-group-exposed inner pore surface. Finally, on benefiting from the long-range fractal opening in 2D MOF support structure, while loaded on an electrode surface, a facilitated cross-interface charge-transportation and well-exposure of immobilized ReI-catalysts are anticipated, thus realizing enhanced activity and stability of the supported catalyst in photoelectrochemical CO2-to-CO reduction. 相似文献