Bandwidth and stability enhancement of optical parametric amplification using chirped ferroelectric superlattice

We report a theoretical analysis and numerical simulation of bandwidth and stability enhancement in optical parametric amplification (OPA) when using chirped periodically poled KTiOPO₄. Calculation results show that the bandwidth and stability are enhanced significantly by the use of a chirped grating. Temperature-gradient and fanned gratings are introduced and chirp factors of them are deduced and calculated. The use of a fanned grating flattens the Quasi-phase-matching response and improves the efficiency. Finally, we propose a method to reduce the instability induced by an unstable pump.     

I-V curve oscillation observed by atomic force microscopy

Oscillation on the current-voltage curve measured by atomic force microscopy is observed when the distance between the tip and sample is large enough and beyond a critical value. The appearance of the oscillation is attributed to the excitation of electron standing waves between the tip and sample. From the first peak position and the voltage difference between the first two peaks on the current-voltage curve, the value of the work function at the detected point on silver film surface and the distance between the tip and the detected point can be calculated.     

Calculation of Specific Heat for Aluminium Thin Films

We employ Prasher＇s non-dimensional form to analyse the size effects on specific heat of Al thin films. Compared the calculation results of pure aluminium film with the experimental data, it is found that the reduction of phonon states is not the main reason of the size effect on the specific heat Al thin films with thickness from lOnm to 37Onm. However, the Al thin film in air usually has an oxidation layer and the specific heat of the layer is smaller than Al. By including the contribution of the oxidation layer to the thin-film specific heat, the calculation results are much closer to the experimental data. This may be a possible reason of the size effects on specific heat of Al thin films.     

Design,synthesis and biological evaluation of biphenylurea derivatives as VEGFR-2 kinase inhibitors(Ⅱ)

Inhibition of VEGFR-2 signaling pathway is one of the most promising approaches for the treatment of cancer. In this paper, we reported the design, synthesis, and biological evaluation of a series of biphenylurea derivatives as VEGFR-2 inhibitors. Among these compounds, 39 exhibited potent inhibitory activity against VEGFR-2 both in vitro and in vivo. The antiangiogenesis activity of 39 was further confirmed by both tube formation assay and chick chorioallantoic membrane assay.     

Identification and determination of the major constituents in Kai‐Xin‐San by UPLC‐Q/TOF MS and UFLC‐MS/MS method

In order to have overall chemical material information of Kai‐Xin‐San (KXS), the reliable ultra‐high‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometer (UHPLC–Q‐TOF‐MS) and ultra‐fast liquid chromatography mass spectrometer (UFLC‐MS/MS) methods were developed for the identification and determination of the major constituents in KXS. Moreover, the UHPLC–Q‐TOF‐MS method was also applied to screen for multiple absorbed components in rat plasma after oral administration of KXS. The UHPLC–Q‐TOF‐MS method was achieved on Agilent 6520 Q‐TOF mass and operated in the negative ion mode. Good separation was performed on a ZORBAX Eclipse Plus C18 column with a gradient elution at a flow rate of 0.2 ml/min. A total of 92 compounds in KXS were identified or tentatively characterized based on their exact molecular weights, fragmentation patterns, and literature data. A total of 26 compounds including 23 prototype components and three metabolites were identified in rat plasma after oral administration of KXS. Then, 16 major bioactive constituents were chosen as the benchmark substances to evaluate the quality of KXS. Their quantitative analyses were performed by a triple quadrupole tandem mass spectrometer (MS/MS) operating in multiple‐reaction monitoring mode(MRM). The analysis was completed with a gradient elution at a flow rate of 0.4 ml/min within 35 min. The simple and fast method was validated and showed good linearity, precision, and recovery. Furthermore, the method was successful applied for the determination of 16 compounds in KXS. All results would provide essential data for identification and quality control of active chemical constituents in KXS. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and Characterization of a Fluorinated Phenolic Resin/phenolic Resin Blend

Fluorine atoms were introduced into the molecular chain of a phenolic resin (PR) by a two-step acid synthesis process to improve its thermal and hydrophobic properties. The successful synthesis of a fluorinated phenolic resin/phenolic resin blend (F-PR/PR) was proven by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance 19F (¹⁹F-NMR). The thermal properties of F-PR/PR were analyzed by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) and the results indicate that the F-PR/PR had good thermal stability. The hydrophobic properties of PR were effectively modified as demonstrated by the water drop contact angles. The flexural and tribological properties of F-PR/PR were also investigated. The fluorine atom, by virtue of its electronegativity, size and bond strength with carbon, can be used to create composites from F-PR/PR with remarkable properties. For comparison, two other resin blends were also synthesized.     

Thermal Degradation Behavior and Kinetics of Polybenzoxazine Based on Bisphenol-S and Allylamine

The thermal degradation behavior of polybenzoxazine based on bisphenol-S/allylamine was studied by Fourier transform–infrared spectroscopy and thermogravimetry–mass spectrometry. The reaction proceeded through detaching of Schiff bases and cleavage of aromatic C–S bonds and the Mannich bridge structures; the scission temperature of the aromatic C–S bond was lower than those of C–N and C–C bonds. The activation energy of the thermal degradation was evaluated with the Flynn–Wall–Ozawa method.     

Source-Manipulating Wavelength-Dependent Continuous-Variable Quantum Key Distribution with Heterodyne Detectors

The intensities of signal and local oscillator (LO) can be elegantly manipulated for the noise-based quantum system while manipulating the wavelength-dependent modulation in source to increase the performance of the continuous-variable key distribution in terms of the secret key rate and maximal transmission distance. The source-based additional noises can be tuned and stabilized to the suitable values to eliminate the effect of the LO fluctuations and defeat the potential attacks in imperfect quantum channels. It is firmly proved that the secret key rate can be manipulated in source over imperfect channels by the intensities of signal and LO with different wavelengths, which have an effect on the optimal signal-to-noise ratio of the heterodyne detectors resulting from the detection efficiency and the additional electronic noise as well. Simulation results show that there is a nice balance between the secret key rate and the maximum transmission distance.     

Application of the Ru(bipy)2(dpp)2+ / C2O4 2− electrochemiluminescence reaction to the determination of phenol

The electrochemiluminescence (ECL) of the ruthenium di(2,2′-bipyridine)- (4,7-diphenyl-1,10-phenanthroline) complex (Ru-bipy-dpp) produced on a glassy carbon electrode was studied by cyclic voltammetry. The anodic oxidation of Ru-bipy-dpp produces ECL in the presence of oxalate in oxygen-free aqueous solutions. Threefold ECL efficiencies were obtained for Ru-bipy-dpp relative to Ru(bipy)₃ as a standard. The ECL of Ru-bipy-dpp is quenched by both oxygen and phenol. The luminescence intensity was proportional to the concentration of phenol in the range of 5–100 μM. At a phenol concentration of 100 μM, the ECL of Ru-bipy-dpp peaking at 597 nm was completely quenched. Correspondence: Dan Xiao, College of Chemistry and Chemical Engineering, Sichuan University, Chengdu 610065, P.R. China