Adrenaline (AD) plays a vital role in the functioning of the central nervous system and the cardiovascular systems. We proposed a fluorescence probe for adrenaline detection based on the modified carbon quantum dots (CQDs). Carbon quantum dots were synthesized by the hydrothermal method, in which citric acid was used as a carbon source, and then modified with ammonia solution. Fluorescence spectrophotometer, transmission electron microscope and Fourier infrared spectroscopy were used to characterize the modified CQDs, respectively. CQDs modified with ammonia have strong fluorescence intensity and emit blue light under ultraviolet light. The adrenaline was related to the quenching fluorescence of CQDs, which was caused by the electron transfer between CQDs and adrenaline quinone under alkaline conditions. The optimum pH value and reaction time of the adrenaline detection used by CQDs were determined to be 10.14 and 300 seconds, respectively. A good linear dependence between the fluorescence intensity ratio of the CQDs and adrenaline concentration(10~100uM) was found after the introduction of a modified Stern-Volmer equation.
We propose a novel absorber with over 90% absorption and is not sensitive to polarization at mid-infrared frequencies (from 31.37 THz to 34.14 THz, 2.77 THz broadwith). The structure of the graphene absorber is special in that it has MgF<sub>2</sub> and SiO<sub>2</sub> multilayer stacking unit cells and arrayed on an Au film plane, which can be easy to fabricate under current manufacturing technology. We can adjust the position of the absorption bands by tuning the Fermi energy without changing the geometric parameters of the complex three-dimensional structure. The tunability of this metamaterial absorber can be achieved via changing the external gate voltage to modify the Fermi energy of graphene. Simulation results demonstrate that the absorption efficiency of the proposed structure can be as high as more than 90% from 28.7THz to 34.14 THz with variation of the Fermi energy from 1.6 eV to 2.0 eV. At the same time, we can also change the Fermi energy to achieve high absorption or high reflection of the absorber.
Graphene has been reported to show polarization-dependent optical absorption in the visible spectral range, that it shows more absorption for s-polarized light than p-polarized light. We study further on it and demonstrate that this unique property can be utilized to design a fiber optic sensor, which works in a similar way of surface plasmon resonance (SPR) fiber optic sensor. However, they are based on different mechanisms. Numerical simulation reveals that graphene layer of 5 nm is appropriate for the fiber optic sensor to achieve its best sensing performance, with a high sensitivity from 1700 to 6900 nm/RIU (refractive index unit).
Aiming at the problem that the damage threshold of gold coated grating is relatively low, a dielectric film is considered on the gold coated gratings as a protective layer. The thickness range of the protective layer is determined under the prerequisite that the diffraction efficiency of the gold coated grating is reduced to an acceptable degree. In this paper, the electromagnetic field, the temperature field and the stress field distribution in the grating are calculated when the silica and hafnium oxide are used as protective layers, under the preconditions of the electromagnetic field distribution of the gratings known. The results show that the addition of the protective layer changes the distribution of the electromagnetic field, temperature field and stress field in the grating, and the protective layer with an appropriate thickness can improve the laser damage resistance of the grating.
Particle stacking structured SiO<sub>2</sub> porous films were prepared by sol-gel method. A model has been established to analyze
the heat conductivity of these films. It is assumed that the heat energy mainly transfers through particles and their contact
points. In particle stacking structured materials, a particle contacts with twelve contiguous particles, and forms twelve
heat conduction branches. This model is suit to the conditions that: the size of particles in the porous material is uniform;
heat conductivity of particle skeleton is much greater than particle clearance; and all contact area between particles
approximately equal. The results show that: heat conductivity of particles stacking porous material is anisotropic,
material heat conductivity depends on that of the particle skeleton and the ratio between radiuses of particle contact area
and particle itself.
Coating material has been considered as being made up of a lot of small tablets. These tablets have plane surface during the whole film
preparation process. Based on the assumption that a column etching pit will form in coating material when electron beam is used for heating,
influences of the etching pit's dimension and the internal structure of the vacuum chamber on films thickness uniformity have been
investigated. Results reflect that the appearance of etching pit does not always cause negative influence on films thickness uniformity. The
negative impact of etching on films thickness uniformity can be reduced by optimizing the internal structure of the vacuum chamber and
preparation technical parameters. But, it is difficult to achieve the beneficial action. This investigation is useful to help us understand physical
meaning of the emission characteristics of the evaporation particle and design experimental scheme.
The conditions that the droplet's thermodynamic parameters change with time have been calculated, and the contrast between them when
different laser pulse patterns are selected have been analyzed accordingly. The results show that: Two atomization processes are formed, and
the second one is not evident for the case of gaussian distribution laser pulse. The change trend of the time-related expansion velocity is first
increased, then decreased for the case of flat top distribution laser pulse, and is first increased, then maintained for the case of gaussian
distribution laser pulse. The expansion process displays a stable stage in which the expansion velocity fluctuates slightly after atomization for
the case of gaussian distribution laser pulse. In the terminal phase of the laser pulse, negative expansion acceleration appears for the case of flat
top distribution laser pulse. The time-related temperature variations are more complicated for the case of flat top distribution laser pulse.