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11.
Nhat Anh Thi Thieu Minh Canh Vu Dae Hoon Kim Won Kook Choi Sung‐Ryong Kim 《先进技术聚合物》2020,31(10):2351-2359
The composites comprising vertically aligned network of copper nanowires (CuNWs) in the presence of cellulose nanofibers were fabricated by using the freeze‐templating method and the effect of aspect ratio (A/R) of CuNWs on the thermal conductivity of epoxy composites was investigated. The thermal conductivity of epoxy composites increased to 0.79 W m?1 K?1 at 1.12 vol% of high A/R CuNWs loading, corresponding to the thermal conductivity enhancement of 365% as compared to the pure epoxy. The thermal conductivity of vertically aligned higher A/R CuNWs/epoxy, which is 38.5% and 51.9% higher than those of the lower A/R CuNWs and the randomly aligned CuNWs, respectively. The application of the epoxy composites in heat dissipation was demonstrated by the temperature changes of composites on a hot plate with the increase of heating time. These results indicate that the thermally conductive composites in this study could be applied for thermal dissipating materials in electronic devices. 相似文献
12.
In this research experiments were performed to examine the hydrodynamic diffusion of spherical particles in a highly filled
suspension. The suspension consisted of nearly monodisperse polymethylmethacrylate spheres in a density matched polymer solution.
The polymer solution was prepared by dissolving 0–700 ppm of polyacrylamide in a mixture of ethyleneglycol and glycerine.
The polymer solution did not show appreciable shear thinning. The particle loading was varied from 30 to 55%. The hydrodynamic
diffusivity was estimated by measuring the time-dependent viscosity when the suspension was subjected to a circular Couette
flow with an air bubble trapped under the rotor of the Couette apparatus. The results show that the dimensionless diffusivity
(D/γ˙a
2) of particles in polymer solution is not proportional to shear rate (γ˙), as in the case of a Newtonian fluid, but that it
decreases with increasing shear rate. The diffusivity also decreases with increasing polymer concentration. It is suggested
that the elongational thickening behaviour and the increased lubrication force due to the first normal stress difference may
be responsible for the reduction of diffusivity in the polymer solution.
Received: 18 January 2000 Accepted: 6 April 2000 相似文献
13.
Alan M. Kook Stanford L. Smith Ellis V. Brown 《Magnetic resonance in chemistry : MRC》1984,22(11):730-733
Hydrogen and carbon chemical shifts and H? H and C? H couplings are reported for six aminoquinolines and six aminoisoquinolines in DMSO-d6. 相似文献
14.
Novel and unusual dimerization reaction of α-chloroacetoacetanilide under basic reaction condition to give structurally unique 6-oxa-3-azabicyclo[3.1.0]hexane was described. 相似文献
15.
An efficient one-step method to prepare aryl-substituted carbazoles via tandem double or triple CC bond formations by multiple Suzuki couplings and CN bond formation by Cadogan cyclization has been developed. The developed method employs commercially available or easily preparable polybromonitrobenzenes and arylboronic acids as starting materials, tolerates various functional groups, and provides good yields. 相似文献
16.
17.
Based on the structures of natural sphingolipids, we designed heterocyclic sphingoid base mimetics in which the conformational restriction is introduced by incorporation of a pyrrolidine moiety between the 2-amino group and the C-4 carbon atom of the sphingoid base. Our synthesis features a regioselective nucleophilic ring opening of a cyclic sulfate with cyanide and subsequent manipulation of the cyanide group. During the course of synthesis, Staudinger-type reductive cyclization of 1,3-azido carboxylic acid and 1,4-azido alcohol offers a direct route to the five-membered pyrrolidone and pyrrolidine products. The preliminary biological evaluation indicates that the designed pyrrolidine analog is biologically active and its cytotoxic effect is associated with the induction of apoptosis. 相似文献
18.
The marine macrolide bryostatin 7 is prepared in 20 steps (longest linear sequence) and 36 total steps with five C-C bonds formed using hydrogenative methods. This approach represents the most concise synthesis of any bryostatin reported, to date. 相似文献
19.
The carbamoylphosphosphonate silane (CMPO analogue; 2-(diphenylphosphoryl)-N-(3-(triethoxysilyl)propyl) acetamide) modified mesoporous silica was prepared via a post-synthesis grafting method for the effective purification of rare earth elements. The guest CMPO analogue was synthesized by direct coupling reaction of 2-(diphenylphosphoryl) acetic acid and 3-(triethoxysilyl)propan-1-amine. Various mesoporous silicates such as MCM-41, SBA-15, or amorphous silica nanoparticles were adopted as host materials. The resulting surface-modified mesoporous materials were characterized with respect to their structural integrity, surface area, and pore size and the concentration of the CMPO silane species. These CMPO functionalized periodic mesostructured silicates offer the potential of applications as catalysts, sensors, or environmental sorbents. 相似文献
20.
Hyun Suk Seo Yeong Mu Ko Jae Won Shim Joong-Ki Kook Byung Hoon Kim 《Applied Surface Science》2010,257(2):596-602
Plasma surface modification can be used to improve the surface properties of commercial pure Ti by creating functional groups to produce bioactive materials with different surface topography. In this study, a titanium surface was modified with acrylic acid (AA) using a plasma treatment and immobilized with bioactive arginine-glycine-aspartic acid (RGD) peptide, which may accelerate the tissue integration of bone implants. Both terminals containing the -NH2 of RGD peptide sequence and -COOH of poly(acrylic acid) (PAA) thin film were combined with a covalent bond in the presence of 1-ethyl-3-3-dimethylaminopropyl carbodiimide (EDC). The chemical structure and morphology of AA film and RGD immobilized surface were investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All chemical analysis showed full coverage of the Ti substrate with the PAA thin film containing COOH groups and the RGD peptide. The MC3T3-E1 cells were cultured on each specimen, and the cell alkaline phosphatase (ALP) activity were examined. The surface-immobilized RGD peptide has a significantly increased the ALP activity of MC3T3-E1 cells. These results suggest that the RGD peptide immobilization on the titanium surface has an effect on osteoblastic differentiation of MC3T3-E1 cells and potential use in osteo-conductive bone implants. 相似文献