Near-unity quantum yield and long-term emission stability in halide perovskite nanocrystal glass composite.

Metal halide perovskites are promising optoelectronic materials due to their outstanding luminescent properties. However, the instability of perovskites has long been the bottleneck to their practical applications. Here Cs4PbBr6 nanocrystals based glass composite (Cs4PbBr6 NCs@glass) are successfully prepared, which displays green emission color (520 nm), narrow bandwidth (23 nm) and a near-unity photoluminescence quantum yield (PLQY). The H2O molecules permeating in the lattice of Cs4PbBr6 were found to be a crucial role in the subband energy emission. The Cs4PbBr6 NCs@glass has excellent emission stability; maintains 93 % of initial PL intensity after ultraviolet light irradiation for over 5000 h. In addition, by adjusting the halogen content, we have achieved tunable emission color from blue (450 nm) to green (520 nm) and red (670 nm) on Cs4PbX6 NCs@glass (X = Cl, Br, I), which covers up to 127 % of the National Television Systems Board (NTSC) standard system. Our finding indicates the commercial applications of perovskite materials in lighting and display.

Characterizations for the photothermal effect of Rhodamine 6G using white-light interferometry and windowed Fourier transform.

Photothermal phenomenon is one of the natural responses in light-matter interactions in which the energy of the incident light is converted into heat, resulting in a temperature increase in the illuminated material. This effect has a direct influence on the refractive index of the material such that its change of spectral dependency with temperature can be exploited for different applications. However, it is also important to separate/identify the thermal effect from the optical/electronic resonance effect to expand potential applications of light-matter interactions. In this work, we demonstrate the use of a white-light interferometry approach combined with a windowed Fourier transform method and a consistency-checking peak-fitting method to obtain the refractive index of an Rh6G-ethanol dye solution with a sensitivity of about ∼10-6 (RIU) for the visible range. Moreover, we also perform both static and dynamic measurements to study the photothermal effect of the Rh6G solution under external excitation. Importantly, we separate the optical and thermal effects due to the external excitation and obtain very good agreement with the experimental results by modeling the relative refractive index of the Rh6G solution with an expression consisting of spectrally a Fano-like resonance term and a linear dependent thermal term. We find that the response due to the optical effect is about ∼0.2 × 10-3 of that due to the thermal effect in the low-light regime. Our approach to separating the optical and thermal effects could shed light on other fields for potential applications through precision measurements of the transmission phase or refractive index.

The deposition and wet etching of Mg-doped ZnO films and their applications for solidly mounted resonators.

In this report, a solidly mounted resonator (SMR), consisting of an Au electrode, Mg-doped ZnO (Mg X Zn1-X O) piezoelectric film and Bragg acoustic reflector, was fabricated on a Si substrate by radio frequency (RF) magnetron sputtering. As a key processing step for the SMR, Mg X Zn1-X O films with high c-axis orientation were fabricated and the crystalline structure, surface morphology and roughness of the films were investigated. The surface morphology, optical transmittance and shape control of Mg X Zn1-X O films were investigated by the chemical wet-etching method with various etchants. The profiles and line patterns of Mg X Zn1-X O films etched with FeCl3·6H2O solutions are satisfactory and fully meet the industrial requirements. The Bragg acoustic reflector, made entirely of metal, has small internal stress and good heat conduction. An SMR based on a Mg X Zn1-X O piezoelectric film shows a resonant frequency of 2.402 GHz, and the k eff 2, Q S and Q P of the SMR are 3.07%, 415 and 546, respectively.

Solidly mounted resonator sensor for biomolecule detections.

We report the fabrication of a solidly mounted resonator (SMR) that can also function as a sensor for biological molecules. The SMR, consisting of a Au electrode, aluminum nitride (AlN) piezoelectric thin film and Bragg acoustic reflector, was fabricated on a Si substrate by radio frequency (RF) magnetron sputtering. The Bragg acoustic reflector, made entirely of metal, has small internal stress and good heat conduction. Human immunoglobulin G (IgG) antibody was immobilized on the modified (by self-assembled monolayer method) Au electrode surface of the SMR and goat anti-human IgG antigen was captured through the specificity of bond between the antibody and antigen on the electrode surface. We found a linear relationship between the resonant frequency shift and the concentration of goat anti-human IgG antigen for concentrations smaller than 0.4 mg ml-1 and a relatively constant frequency shift for concentrations greater than 0.5 mg ml-1. A series of interference experiments can prove that the selectivity of the sensor is satisfactory. Our findings suggest that the SMR sensor is an attractive alternative for biomolecule detection.

[Lentinan induces the expression of human-beta-defensin-2 in pulmonary epithelial cells].

To determine whether lentinan could upregulate the expression of human-beta-defensin-2(HBD-2) in pulmonary epithelial cells (SPC-A-1), we stimulated pulmonary epithelial cells with lentinan and detected the expression of HBD-2mRNA by RT-PCR test. The results demonstrated that the expression of HBD-2mRNA in SPC-A-1 could be induced by lentinan in a concentration and time-dependent manner.

[Houttuynia Cordata induces expression of human beta-defensin-2 mRNA in pulmonary epithelial cells in vitro].

OBJECTIVE: To explore the effects of Houttuynia Cordata on expression of human beta-defensin-2 (HBD-2) in pulmonary epithelial cells (SPC-A-1) in vitro; and to observe the correlationship between the level of HBD-2 mRNA and the concentrations or treatment times of Houttuynia Cordata. METHODS: The SPC-A-1 cells were cultured with different concentrations of Houttuynia Cordata in vitro, including 0, 12.5, 25, 50, 100 and 200 microg/ml. And then, the SPC-A-1 cells were cultured with the optimal concentration of Houttuynia Cordata in different lengths of time, including 1, 2, 4, 8, 16 and 24 hours. After the treatment, the mRNA level of HBD-2 in pulmonary epithelial cells was detected by means of semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS: After being cultured with Houttuynia Cordata, the expression of HBD-2 mRNA had positive correlation with the stimulus concentrations (rs=0.829, P=0.042) and stimulus time (rs=0.914, P=0.003). The highest expression of HBD-2 mRNA was induced by 100 microg/ml Houttuynia Cordata after 8-hour treatment. In comparison with the normal control group and the interleukin-1beta group, 100 microg/ml Houttuynia Cordata could significantly up-regulate the expression of HBD-2 mRNA in SPC-A-1 cells after 8-hour treatment (P<0.01). CONCLUSION: Houttuynia Cordata can up-regulate expression of HBD-2 mRNA in SPC-A-1 cells, and the highest expression level of HBD-2 mRNA can be obtained by culture with 100 microg/ml Houttuynia Cordata for 8 hours.

Symmetrical 1x2 digital photonic splitting switch with low electrical power consumption in SiGe waveguides.

A symmetrical digital photonic splitting switch with a low insertion loss and a low driving voltage is developed using carrier injection in a silicon-germanium material for optical communication systems and networks at a wavelength of 1.55 mum. The switch structure has been improved based on a traditional 1x2 Y-shaped configuration by using two widened carrier injection regions. The switch has a threshold voltage of 1.0 V and a corresponding threshold current of 85 mA on one of the two output waveguide arms. The calculated driving current density is 5.7 kA/cm2 and the calculated power consumption is 85 mW at the 85 mA of threshold current. The measured insertion loss and the crosstalk are 5.2 dB and -9.6 dB, respectively, at driving voltage over 2 V.