Ultrasound-assisted extraction of phillyrin from Forsythia suspensa

Forsythia suspensa (Thunb.) Vahl is one of the most widely used traditional Chinese medicines, and possesses important biological activities, such as antibacterial, antiviral, anti-inflammatory and antioxidant activities. Phillyrin is the main bioactive component of Forsythia suspensa. In this paper, ultrasound-assisted extraction of phillyrin from Forsythia suspensa was studied with HPLC-photodiode array detection. Effects of several experimental parameters, such as type and concentration of extracting solvent, ratio of liquid to material, extraction temperature, and time of sonication on extraction efficiencies of phillyrin from Forsythia suspensa were evaluated. The optimal extraction conditions were 1g plant sample with 10 ml of 20% methanol and the extraction for 60 min at 60°C under ultrasonic irradiation. Under the optimum conditions, the yield of phillyrin was 0.713±0.009 mg/g. The results indicated that the ultrasound-assisted extraction is a very useful method for the extraction of important phytochemicals from plant materials.     

Composition, microstructure, and properties of CrNx films deposited using medium frequency magnetron sputtering

CrN_x films were deposited on stainless steel and Si (1 1 1) substrates via medium frequency magnetron sputtering in a N₂ + Ar mixed atmosphere. The influence of N₂ content on the deposition rate, composition, microstructure, mechanical and tribological properties of the as-deposited films was investigated by means of the X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), nanoindentation and tribometer testing. It was found that the N atomic concentration increased and the phase transformed from a mixture of Cr₂N + Cr(N) to single-phase Cr₂N, and then Cr₂N + CrN to pure CrN phase with the increase of N₂ content. The Cr 2p_3/2 and N 1s of XPS spectra also confirmed the evolution of phase. Accordingly, all films exhibited a typical columnar structure which lies in the zone T of Thornton Model. The mixed Cr₂N and Cr(N) phases showed low hardness and high friction coefficient. Cr₂N possessed higher hardness than CrN while CrN exhibited lower friction coefficient.     

Liquid-crystal-based tunable high-Q directional random laser from a planar random microcavity

Temperature-tunable directional laser emission from a dye-doped liquid-crystal-based planar random cavity laser is presented. The optically pumped nematic liquid crystal infiltrated planar random microcavity produces an ultranarrow linewidth (0.03 nm, corresponding to Q>20,000), highly directional (1.4 degrees divergence angle) laser emission. By increasing the temperature from 27 degrees C to 34 degrees C, the wavelength of an emitted polarized laser can be tuned between 605.8 and 608.5 (ordinary light) and 631.3 and 624.9 nm (extraordinary light). A simulation result from the transfer matrix method that matches the experimental results well is also presented.     

Three-dimension direct writing TiO<Subscript>2</Subscript> crystalline patterns in Bi-free glass using femtosecond laser

Crystalline TiO₂ was induced three dimensionally inside Bi-free glass sample by an 800 nm, 250-kHz femtosecond laser irradiation. Micro-Raman spectra analysis indicated that the laser-induced crystals in the focal point of the laser beam were monophase TiO₂ rutile. Continuous crystalline lines were written through moving the focal point of the laser beam inside the glass. The results demonstrate that this technique is a convenient method to engrave three-dimensional patterns of crystals for fabricating integrated optical devices in transparent materials.     

Phase locking of a compact Nd-doped phosphate multicore fiber laser

Two compact fiber lasers based on the gain medium of Nd-doped phosphate glass multicore fiber (MCF), of length no more than 10 cm, have been demonstrated experimentally for the first time. A stable phase-locked laser beam at 1055 nm emitted from a three-core fiber that is 8.5 cm in length has been achieved, with a maximum output power of 20 mW. The properties of similar seven-core fiber laser also have been investigated.     

光栅减反层太阳能电池光电转换效率的研究

运用时域有限差分方法,研究了光栅减反层结构对太阳能电池光电转换效率及储能效果的影响.具体从光栅形状、高度以及光栅表面金属薄膜厚度出发.结果表明经光栅减反层优化表面结构的太阳能电池的光电转换效率显著增大,储能效果大大得到提升.尤其是三角形光栅太阳能电池.随着镀层厚度的增加,储能效果增加,但当薄膜厚度过厚时,储能效果反而降低.     

Diffusion and ballistic contributions of electron-electron interaction to the conductivity in an Al0.26Ga0.74N/AlN/GaN heterostructure

The results of an experimental study of quantum correction of electron-electron interaction (EEI) to the conductivity of two-dimensional electron gas (2DEG) in an undoped heterostructure are reported. A small but significant decrease of the Hall slope with the increase of temperature was discovered. This is not due to the increase of electron concentration as temperature increases but to the EEI effect. Both diffusion and ballistic contributions of EEI to the conductivity of 2DEG were observed. As the temperature increases, the negative diffusion EEI correction to the conductivity increases in an absolute value while the ballistic EEI correction reduces to a renormalization of the transport mobility.     

CdSe quantum dots decorated by mercaptosuccinic acid as fluorescence probe for Cu

Water-soluble CdSe quantum dots (QDs) were synthesized using mercaptosuccinic acid (MSA) as a stabilizer. The growth process and characterization of CdSe quantum dots were determined by transmission electron microscopy (TEM), X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, Ultraviolet-visible (UV-vis) spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. Results demonstrated the MSA-capped CdSe QDs were highly crystalline and possessed good optical properties. Further, the resulting products could be used as fluorescent probes to detect Cu²⁺ ions in physiological buffer solution. The response was linearly proportional to the concentration of Cu²⁺ ion in the range 2×10⁻⁸- 3.5×10⁻⁷ mol L⁻¹ with a detection limit of 3.4 nmol L⁻¹.     

The Marple algorithm for the autoregressive spectral estimates of the SMMW fourier transform spectroscopy data

The Marple algorthm for the autoregressive spectral estimates has been applied to the SMMW Fourier transform spectrum analysis. The experimental results have shown that this method yields AR spectra with three times higher resolution than the FFT method does. The improvements obtained from the Marple algorithm over the maximum entropy algorithm include higher resolution, less bias in the spectral peak frequency estimation and absence of observed spectral line splitting. The effects of the structure of the spectral lines and the noise on the resolution are discussed.Projects supported by National Natural Science Foundation of China     

Can we explain the coexistence of ferromagnetism and superconductivity based on two parameters model?

A possible explanation about the coexistence of ferromagnetism (FM) and superconductivity (SC) based on a two parameters mean field model in a two-dimensional system is discussed. The key feature of this model is that there are two independent parameters which are responsible for ferromagnetism and superconductivity, respectively. We point out that the coexisting FM and s-wave pairing SC state is energetically not favorable among all possible state. We generalize the two parameter model to include the coexistence of FM with p-wave SC. We find that the phase diagram is not consistent with what experimentally discovered in UGe₂.