Optical design of high performance con-focal microscopy with digital micro-mirror and stray light filters

This research proposes a newly developed stray light filter in order to eliminate stray light, which otherwise might severely reduce the performance of the con-focal microscopy presented in this research. First, an optical design for con-focal microscopy with a digital micro-mirror device (DMD) is illustrated; second, a newly developed stray light filter is presented, which functions to eliminate possible stray light and ghost images without any sacrifice of luminance. It indicates that not only can the optical system be much simplified but also that its resolution could be one step higher, because the system employs neither a pinhole nor a CCD camera lens. Experimental results are shown in the paper, demonstrating an increase in contrast of up to 60%.     

Trapping a dark soliton pulse within a nano ring resonator

We propose the interesting results that a dark soliton pulse can be localized within a nonlinear nano-waveguide. The system consists of nonlinear micro and nano ring resonators, whereas the dark soliton can be input into the system and trapped within the nano-waveguide. A dark soliton pulse is input into a ring resonator and chopped to be the smaller pulses. The required pulse is filtered and amplified, which can be controlled and localized within the nano-waveguide. The localized bright soliton is also reviewed and discussed.     

A new concept of white light generation using a nano-waveguide for the solar radiation collection use

We propose a novel system of a nano-waveguide that can be used to generate the continuous optical spectrum, i.e. white light. A system consists of two micro-ring resonators and a nano-ring resonator that can be integrated into a single system. The large bandwidth signal is generated using a soliton pulse propagating within a Kerr-type nonlinear medium, whereas the continuous bandwidth or wavelength of light signal can be performed. Results obtained have shown the potential of using such a system for white light source generation and amplification, which is discussed. The amplified pulse can be stored within a nano-waveguide, which is allowed to form the continuous spectrum after amplification. Alternatively, the low-level solar radiation can be amplified, and the bandwidth signals can also be enlarged.     

The analysis of spatial light to Bragg fiber coupling ratio

On the basis of the electromagnetic field mode matching theory, the coupling efficiency ratio from spatial light to Bragg fiber is analyzed, which shows that the coupling efficiency ratio is related to the radius of focused facular, the core radius of Bragg fiber and wave number of the core. By optimizing the value of such parameters appropriately, the Bragg fiber coupling efficiency ratio can be improved. It is also important for the analysis of the coupling efficiency of Bragg fiber, which can be applied to the free optical communication system and laser radar system.     

A one-pot method to prepare N-doped titania hollow spheres with high photocatalytic activity under visible light

N-doped titania hollow spheres (NTHS) were prepared by a one-pot hydrothermal method using urea as precursor of nitrogen. The prepared hollow spheres were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectrum (DRS). The photocatalytic activity of as-prepared titania hollow spheres was determined by degradation of Reactive Brilliant Red dye X-3B (C.I. reactive red 2) under visible light irradiation, and was compared to non-doped titania hollow spheres and commercial P25 titania. Results indicated that the as-prepared NTHS showed highest photocatalytic activity.     

Enhanced adsorption and visible-light-induced photocatalytic activity of hydroxyapatite modified Ag-TiO2 powders

In order to get a kind of materials with enhanced adsorption and photocatalytic performance, hydroxyapatite modified Ag-TiO₂ powders (Ag-TiO₂-HAP) were prepared by a facile wet chemical strategy. The powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy, N₂ adsorption-desorption measurement (BET), photoluminescence spectroscopy (PL), etc. The photocatalytic activities were evaluated by photocatalytic oxidation decomposition of acetone in air under visible-light illumination. The results showed that the coupled system indicated a highest photocatalytic activity and photochemical stability under visible-light irradiation than all the other catalysts. The intensively improved visible-light-induced photocatalytic activity of the Ag-TiO₂-HAP hybrids could be attributed to its strong absorption in the visible-light region, low recombination rate of the electron-hole pair and large BET specific surface area.     

Productivity optimization of microalgae cultivation in a batch photobioreactor process

We address the question of mean biomass volumetric productivity optimization, which originates from the simplification of dynamics of microalgae in a batch bioreactor process with light incidence. In particular, the stability of the model is analyzed, some optimality necessary conditions for the nonsmooth optimization problem obtained through the inclusion of different photoperiods are studied, and the model is applied in the particular case of Chlamydomonas reinhardtii microalgae to validate our results.     

1-平面图的结构性质及其在无圈边染色上的应用

一个图称为是1-平面的如果它可以画在一个平面上使得它的每条边最多交叉另外一条边.本文描述了任意1-平面图中小于等于7度点之邻域的局部结构,解决了由Fabrici和Madaras提出的两个关于1-平面图图类中轻图存在性的问题,证明了每个最大度是△的1-平面图G是无圈列表max{2△-2,△+83}-边可选的.     

Large‐Scale Fluctuation Behavior Prior to the Crystallization of Poly(ethylene terephthalate) Glass: A Small‐Angle Light Scattering Study

The crystallization processes of amorphous, glassy‐state poly(ethylene terephthalate) (PET) at two temperatures, a low temperature near T _g where PET has a slow crystallization speed and a middle temperature (about 55°C above T _g ) where PET crystallization is rapid, were monitored in situ by a time‐resolved small‐angle light scattering (SALS) device. It was found that large‐scale fluctuations happened prior to the crystallization at both temperatures, but the kind of fluctuation had a temperature dependence: at the middle temperature, pure density fluctuation took place during the induction period, whereas at low temperature, both density fluctuation and orientation fluctuation occurred, but the latter was the dominant factor. Analyses of the kinetics of these two kinds of fluctuation processes demonstrated that the spinodal decomposition (SD) type of phase‐separation character was undistinguishable in the SALS scale, while the nucleation‐growth (NG) type of phase behavior could describe the scattering results as well.     

Dynamic Light Scattering Studies on Crystallization of Isotactic Polystyrene from Dilute Solutions at High Supercoolings

Crystallization of isotactic polystyrene (it‐PS) from dilute solution at high supercooling has been investigated by dynamic light scattering (DLS). We successfully obtained simultaneously, in situ in solutions, the time developments of both random coils of it‐PS molecules and the growing crystals. The size of coils remains constant during growth, while the crystals pass through two stages, that is, an induction period at the early stage with very slow growth rates and a subsequent linear growth stage. It is confirmed that the temperature dependence of the linear growth rates, determined by DLS, agree well with that determined by electron microscopy. The temperature dependences of the growth rate and the inverse of induction time are dependent on the viscosity of solvent, which indicates that all dynamics are dominated by the segmental motion of polymer chains in solution at high supercoolings (low temperatures). Two possibilities are proposed for the induction period.