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211.
212.
Yifeng Xiang Xi Tang Changjun Min Guanghao Rui Yan Kuai Fengya Lu Pei Wang Hai Ming Qiwen Zhan Xiaocong Yuan Joseph R. Lakowicz Douguo Zhang 《Annalen der Physik》2020,532(4):1900497
Near-field optical trapping can be realized with focused evanescent waves that are excited at the water–glass interface due to the total internal reflection, or with focused plasmonic waves excited on the water–gold interface. Herein, the performance of these two kinds of near-field optical trapping techniques is compared using the same optical microscope configuration. Experimental results show that only a single-micron polystyrene bead can be trapped by the focused evanescent waves, whereas many beads are simultaneously attracted to the center of the excited region by focused plasmonic waves. This difference in trapping behavior is analyzed from the electric field intensity distributions of these two kinds of focused surface waves and the difference in trapping behavior is attributed to photothermal effects due to the light absorption by the gold film. 相似文献
213.
Li-Bao Fan Yue-Hui Zhou Fen Zou Huan Guo Jin-Feng Huang Jie-Qiao Liao 《Annalen der Physik》2020,532(8):2000134
The quantum thermalization of the Jaynes–Cummings (JC) model in both equilibrium and non-equilibrium open-system cases is studied, in which the two subsystems, a two-level system and a single-mode bosonic field, are in contact with either two individual heat baths or a common heat bath. It is found that in the individual heat-bath case, the JC model can only be thermalized when either the two heat baths have the same temperature or the coupling of the JC system to one of the two baths is turned off. In the common heat-bath case, the JC system can be thermalized irrespective of the bath temperature and the system–bath coupling strengths. The thermal entanglement in this system is also studied. A counterintuitive phenomenon of vanishing thermal entanglement in the JC system is found and proved. 相似文献
214.
以天然矿物为原料,结合中国紫的分子式及多数考古样品的分析结果进行配料(如或多或少都含有铅),对配制并加工好的试样进行热重-差热及变温XRD分析,以探讨古代烧制中国紫颜料时的原料选用及烧制条件等问题,为揭示诸如中国紫产生在中国的原因等问题提供依据。结果表明利用毒重石(BaCO3)配料,能够较容易地烧制出中国紫,这意味着中国紫的出现可能与这种独特的含钡矿物资源有关。 相似文献
215.
216.
Near-field thermoelastic imaging is a simple way to investigate the thermal and coupled thermoelastic properties of materials. A few microscopes, deriving from the atomic force microscope, have been used to observe and to quantify the samples observed. But the main problem is the absolute measurement of the temperature, because surface topography and thermal expansion contributions are not easily discernible. In the proposed SThEM (scanning thermoelastic microscope), the tip is excited at the resonance frequency of the cantilever and the sample is periodically heated by the Joule effect. Thus the static contributions (drift, topography) are reduced. Moreover, a radiometric sensor, operating in the far field, has been added in order to quantify the temperature. This multi-acquisition microscope enables one to investigate small objects at the nanoscale with complementary information at the micrometric scale. 相似文献
217.
Local thermal conductivity of polycrystalline AlN ceramics measured by scanning thermal microscopy and complementary scanning electron microscopy techniques 下载免费PDF全文
The local thermal conductivity of polycrystalline aluminum nitride (AlN) ceramics is measured and imaged by using a scanning thermal microscope (SThM) and complementary scanning electron microscope (SEM) based techniques at room temperature.The quantitative thermal conductivity for the AlN sample is gained by using a SThM with a spatial resolution of sub-micrometer scale through using the 3ω method.A thermal conductivity of 308 W/m·K within grains corresponding to that of high-purity single crystal AlN is obtained.The slight differences in thermal conduction between the adjacent grains are found to result from crystallographic misorientations,as demonstrated in the electron backscattered diffraction.A much lower thermal conductivity at the grain boundary is due to impurities and defects enriched in these sites,as indicated by energy dispersive X-ray spectroscopy. 相似文献
218.
This article examines a mathematical model to analyze the rotating flow of three-dimensional water based nanofluid over a convectively heated exponentially stretching sheet in the presence of transverse magnetic field with additional effects of thermal radiation,Joule heating and viscous dissipation.Silver(Ag),copper(Cu),copper oxide(Cu O),aluminum oxide(Al_2O_3)and titanium dioxide(Ti O_2)have been taken under consideration as the nanoparticles and water(H_2O)as the base fluid.Using suitable similarity transformations,the governing partial differential equations(PDEs)of the modeled problem are transformed to the ordinary differential equations(ODEs).These ODEs are then solved numerically by applying the shooting method.For the particular situation,the results are compared with the available literature.The effects of different nanoparticles on the temperature distribution are also discussed graphically and numerically.It is witnessed that the skin friction coefficient is maximum for silver based nanofluid.Also,the velocity profile is found to diminish for the increasing values of the magnetic parameter. 相似文献
219.
S.?N.?Danil’chenkoEmail author A.?N.?Kulik A.?N.?Bugai P.?A.?Pavlenko T.?G.?Kalinichenko N.?V.?Ul’yanchich L.?F.?Sukhodub 《Journal of Applied Spectroscopy》2005,72(6):899-905
Using x-ray diffraction, electrothermal atomization atomic absorption spectroscopy, and scanning electron microscopy with
an x-ray microanalysis, we have studied the phase decomposition of biogenic and synthetic Mg-containing apatite at 900°C with
formation of β-tricalcium-magnesium phosphate (β-TCMP). Employing simplified model representations, we obtained a relation
that couples the initial Mg concentration with the degree of transformation of apatite into β-TCMP. It is shown that for the
β-TCMP contents measured in bioapatite samples and on replacement of calcium by magnesium to about 8% in this phase the calculated
range of Mg concentrations coincides with that available in literature sources (0.2–0.6 wt. %). A comparative investigation
of the products of decomposition of biogenic and synthetic apatite by the methods of analysis of the composition and structure
has established that the formation of β-TCMP is limited by both the insufficient concentration of magnesium and the small
sizes of the crystals. The results of the investigations carried out together with the experimental data known from the literature
are indicative of the nonuniform distribution of magnesium in the bulk of crystals of biogenic and synthetic apatite, with
its predominant localization at the surface sites of the lattice.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 821–826, November–December, 2005. 相似文献
220.
红外热成像鱼眼镜头设计中若干特殊问题的处理 总被引:7,自引:1,他引:7
提出鱼眼镜头光阑球差的级数表达式及其基于有限差分的近似计算方法,解决了通常的光阑倒追方法面临的难题;讨论孔径光阑与入瞳的特殊"共轭"关系,分析了光阑彗差和像差渐晕;运用Aitkin插值技术填补"溢出"光线在像面上的落点,以保证像质函数定义的一致性,维持自动优化持续进展,从而克服频繁的光线"溢出"造成的严重困难;提出充分利用像差渐晕改善像面照度均匀性的方法;论述标定轴外光束边界的逐次渐近过程和运用入瞳距离变量实现孔径光阑位置全域优化的技术. 相似文献