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排序方式: 共有177条查询结果,搜索用时 15 毫秒
101.
Shan J Chen J Nuopponen M Viitala T Jiang H Peltonen J Kauppinen E Tenhu H 《Langmuir : the ACS journal of surfaces and colloids》2006,22(2):794-801
Amphiphilic thermally responsive gold nanoparticles have been prepared by protecting the particles with both polystyrene, PS, and poly(N-isopropylacrylamide), PNIPAM, chains. Particles form a monolayer on a water surface in a Langmuir trough, and according to in situ spectroscopic measurements, the surface plasmon resonance, SPR, band undergoes a blue-shift during the monolayer compression. The compression-induced blue-shift is related to a change in the conformation of tethered PNIPAM chains; the phenomenon is discussed on the basis of Mie-Drude theory. In contrast, a red-shift in the SPR of the multilayers of the same nanoparticles transferred at different temperatures has been observed with increasing the deposition cycle, attributed to the presence of a weak interparticle coupling in the multilayer. 相似文献
102.
Williamson DC Närväinen J Hubbard PL Kauppinen RA Morris GA 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2006,183(2):203-212
Radiation damping induced by the strong water magnetization in Z-spectroscopy experiments can be sufficient to perturb significantly the resultant Z-spectrum. With a probe tuned to exact electrical resonance the effects are relatively straightforward, narrowing the central feature of the Z-spectrum. Where, as is commonly the case, the probe is tuned sufficiently well to give optimum signal-to-noise ratio and radiofrequency field strength but is not at exact resonance, radiation damping introduces an unexpected asymmetry into the Z-spectrum. This has the potential to complicate the use of Z-spectrum asymmetry to study chemical exchange, for example in the estimation of pH in vivo. 相似文献
103.
104.
Ośmiałowski Borys Kolehmainen Erkki Kalenius Elina Behera Babita Kauppinen Reijo Sievänen Elina 《Structural chemistry》2011,22(5):1143-1151
Abstract
Intermolecular interactions of 7-(RCONH)-[1H]-2-oxo-1,8-naphthyridines (R = Me, Et, i-Pr, t-Bu, 1-adamantyl (1-Ad), CF3, and C2F5) containing ADAD quadruple hydrogen bonding motif were studied by liquid and solid state NMR, ESI-MS, IR, and DFT calculations. 1H NMR was used to determine the dimerization constants of i-Pr and 1-Ad congeners in CDCl3. 13C and 15N cross-polarization (CP) magic angle spinning (MAS) NMR data suggest that compounds possess similar solid state structures. Further, mass spectral data reveal that in gas phase both Me and 1-Ad derivatives form also multimers due to lack of competitive solvent interactions. The structures of the gas phase multimers depend on the size of the alkyl group. These results are in agreement with quantum chemical calculations. Geometry optimization and 1H NMR spectra show that in dimers that carry bulky alkyl groups (t-Bu and 1-Ad) certain hydrogen bonds are weaker than in Me, Et, and i-Pr derivatives while strong electron acceptors, CF3 and C2F5, deshields hydrogen bonded protons but creates significant electronic F/O repulsion yielding lowering of the energy of interaction. The influence of steric effect on dimerization of quadruply hydrogen bonded dimers was correlated with the Taft E s values. 相似文献105.
106.
Hannu Teisala Mikko Tuominen Mikko Aromaa Milena Stepien Jyrki M. Mäkelä Jarkko J. Saarinen Martti Toivakka Jurkka Kuusipalo 《Colloid and polymer science》2013,291(2):447-455
Surface wetting is an important and relevant phenomenon in several different fields. Scientists have introduced a large number of applications where special surface wetting could be exploited. Here, we study wetting phenomena on high- and low-adhesive superhydrophobic liquid flame spray (LFS)-generated TiO2 coatings on paper and pigment-coated board substrates using water–ethanol solution as a probe liquid. Submicrometer-scale air gaps, which exist on superhydrophobic surfaces below the liquid droplets, were more stable with the ethanol increment than the larger-scale micrometric air gaps. With the droplet ethanol concentration of 15 wt%, static contact angle as high as 155?±?2° was measured on the LFS–TiO2-coated board. Transition from the low-adhesive wetting state to the high-adhesive state was demonstrated on the LFS–TiO2-coated paper. The LFS method enables efficient roll-to-roll production of surfaces with special wetting properties on economically viable board and paper substrate materials. 相似文献
107.
He M Chernov AI Fedotov PV Obraztsova ED Rikkinen E Zhu Z Sainio J Jiang H Nasibulin AG Kauppinen EI Niemelä M Krause AO 《Chemical communications (Cambridge, England)》2011,47(4):1219-1221
SiO(2) supported cobalt (Co) catalyst could be partially reduced and anchored by unreduced Co ions during a carbon monoxide (CO) chemical vapor deposition (CVD) process. This resulted in the formation of sub-nanometre metallic Co clusters catalyzing the growth of single-walled carbon nanotubes (SWNTs) with a narrow diameter distribution. 相似文献
108.
V. Koskinen J. Fonsen K. Roth J. Kauppinen 《Applied physics. B, Lasers and optics》2007,86(3):451-454
Recently introduced cantilever enhanced photoacoustic sensing has been applied to the tunable diode laser-based trace gas
detection. The pressure variations due to the photoacoustic signal are detected with a miniature silicon cantilever, whose
displacement is measured with a compact Michelson type laser interferometer. The system has been used to detect carbon dioxide
(CO2) at 1572 nm with a distributed feedback diode laser. With a new photoacoustic cell, that was optimized for the laser sources,
a normalized noise equivalent sensitivity of 1.7×10-10 cm-1W/ at atmospheric pressure was realized. The result obtained in the non-resonant operation mode is at least 10 times better
than in previous reports. The future improvements of the technique are also discussed.
PACS 07.07.Df; 42.55.Px; 82.80.Kq 相似文献
109.
Wu F Queipo P Nasibulin A Tsuneta T Wang TH Kauppinen E Hakonen PJ 《Physical review letters》2007,99(15):156803
We have measured shot noise in single-walled carbon nanotubes with good contacts at 4.2 K at low frequencies (f=600-850 MHz). We find a strong modulation of shot noise over the Fabry-Perot pattern; in terms of the differential Fano factor the variation ranges over 0.4-1.2. The shot noise variation, in combination with differential conductance, is analyzed using two (spin-degenerate) modes with different, energy-dependent transmission coefficients. Deviations from the predictions from Landauer-Buttiker formalism are assigned to electron-electron interactions. 相似文献
110.