3,344 research outputs found
Characteristics of a micro-fin evaporator: Theoretical analysis and experimental verification
A theoretical analysis and experimental verification on the characteristics
of a micro-fin evaporator using R290 and R717 as refrigerants were carried
out. The heat capacity and heat transfer coefficient of the micro-fin
evaporator were investigated under different water mass flow rate, different
refrigerant mass flow rate, and different inner tube diameter of micro-fin
evaporator. The simulation results of the heat transfer coefficient are
fairly in good agreement with the experimental data. The results show that
heat capacity and the heat transfer coefficient of the micro-fin evaporator
increase with increasing logarithmic mean temperature difference, the water
mass flow rate and the refrigerant mass flow rate. Heat capacity of the
micro-fin evaporator for diameter 9.52 mm is higher than that of diameter
7.00 mm with using R290 as refrigerant. Heat capacity of the micro-fin
evaporator with using R717 as refrigerant is higher than that of R290 as
refrigerant. The results of this study can provide useful guidelines for
optimal design and operation of micro-fin evaporator in its present or future
applications
Comparison of form-deprived myopia and lens-induced myopia in guinea pigs
<b>AIM:</b> To study the efficacy difference between form-deprived myopia (FDM) and lens-induced myopia (LIM), the degree of myopia, axial length and pathological changes of the posterior sclera from guinea pigs were evaluated.<b>METHODS:</b> Four-week pigmented guinea pigs were randomly assigned into 3 groups, including normal control (<i>n</i>=6), FDM group with monocular cover (<i>n</i>=11) and LIM group with monocular -7D lens treatment (<i>n</i>=11). FDM group was form-deprived while LIM group was lens-induced for 14 d. Refractive error and axial length were measured prior to and post treatment, respectively. Morphological changes of sclera were examined using both light and electronic microscopes.<b>RESULTS:</b> After 14d treatment, refractive errors for FDM group and LIM group were -3.05±0.71D and -2.12±1.29D, respectively, which were significantly more myopic than that of normal controls and fellow control eyes (<i>P</i><0.01). As for axial length, it was 7.93±0.03 mm for FDM group and 7.89±0.06 mm for LIM group, which were significantly longer than both normal and fellow controls (<i>P</i><0.01). With respect to both refractory error and axial length, the differences between FDM group and LIM group were not significant (<i>P</i>>0.05). Under light microscope, both FDM group and LIM group showed thinned sclera, disarrangement of fibrosis and enlarged disassociation between fibers. Consistently, ultrastructural examination showed degenerated fibroblasts and thinned fibers in posterior sclera.<b>CONCLUSION:</b>Following two weeks of myopia induction in guinea pigs, with regard to the degree of myopia, axial length and pathological alterations, there was no significant difference between FDM and LIM models. Therefore, FDM and LIM are equally effective and useful as a model of experimental myopia and guinea pigs are ideal animals for induction of experimental myopia because their high sensitivity to both form-deprivation and lens-induction
Flexible coherent control of plasmonic spin-Hall effect
The surface plasmon polariton is an emerging candidate for miniaturizing optoelectronic circuits. Recent demonstrations of polarization-dependent splitting using metasurfaces, including focal-spot shifting and unidirectional propagation, allow us to exploit the spin degree of freedom in plasmonics. However, further progress has been hampered by the inability to generate more complicated and independent surface plasmon profiles for two incident spins, which work coherently together for more flexible and tunable functionalities. Here by matching the geometric phases of the nano-slots on silver to specific superimpositions of the inward and outward surface plasmon profiles for the two spins, arbitrary spin-dependent orbitals can be generated in a slot-free region. Furthermore, motion pictures with a series of picture frames can be assembled and played by varying the linear polarization angle of incident light. This spin-enabled control of orbitals is potentially useful for tip-free near-field scanning microscopy, holographic data storage, tunable plasmonic tweezers, and integrated optical components
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