High-power 266 nm laser generation with a NaSr3Be3B3O9F4 crystal.

We demonstrate a 266 nm ultraviolet (UV) picosecond laser by fourth-harmonic generation of a Nd:YAG laser with a 5.4 mm thick NaSr3Be3B3O9F4 (NSBBF) crystal. A maximum output power exceeding 1 W at 266 nm was obtained (the highest output power being 1.6 W), corresponding to a conversion efficiency of 10.3%. The stability measurements on the NSBBF crystal with a fluctuation of 3.34% at 200 mW within 1 h indicate that it is a promising UV nonlinear optical material for practical applications. In addition, for the first time, to the best of our knowledge, we measured the effective nonlinear coefficient of NSBBF crystal at 266 nm and compared it with that of ß-BaB2O4 crystal.

[Fast Classification of Complex Sulphide Ore Based on Raman Spectroscopy].

The regional features, metallogenitic regularities and mineral composition of the hydrothermal sulphide ore have been preliminarily studied. According to the different mineralization period, the patterns of valuable minerals disseminated in ore are complicated, which causes the large changes in the properties of the sulphide ore. The different properties of the sulphide ore may increase the difficulty of the mineral processing and reduce the recovery rate of valuable minerals. Therefore a simple method for rapidly classification of sulphide ore is required to optimize mineral processing flowsheet. Laser Raman spectrometry, as an effective method to analyze the structure of the material is used to identify the component and structure of minerals. The research on the Laser Raman spectra of the large number of sulphide ore samples can reveal the reasons for the difference of the Raman spectra. A new method for classifying the complex sulphide ore using Raman spectroscopy is proposed. The experiment results demonstrate that the properties of the sulphide ore in different mineralization period vary greatly and the fluorescent scattering is mainly produced by gangue minerals. The measured Raman spectral after quenching the fluorescence scattering show the peaks of Raman spectra at 201.62, 242.54, 288.38 and 309.77 cm-1 can be used to identify this kind of complex sulphide ore. The raw ore can be divided into three categories based on the difference of the intensity of fluorescence scattering and the ratio of fluorescence and Raman intensity. The accuracy of the classification method is further validated by the industrial tests. The findings demonstrate the close relationship between Raman spectra and the properties of sulphide ore. The proposed method, which can fast classify the sulphide ore, don't need complex chemical pretreatment before spectra collection. Therefore, this method will have important application value for improving the efficiency of mineral processing.

[Research on explosive temperature network monitoring system based on the linear frequency shift of spectrum].

In order to obtain the different position temperature changes in the process of explosive casting accurate, stability and comprehensive, we designed the temperature monitoring system based on fiber Bragg grating spectral shift. Through the fiberoptic network, the system can monitor the different point temperature of melt-cast explosive real-time. According to the function of linear frequency shift of fiber Bragg grating wavelength with the grating of temperature, we get the temperature of different positions. Four channels share a broadband light source with a coupler. The Bragg wavelengths of the 5 gratings of each fiber are separated from each other. Using the gratings designed, spliced and packaged by our own, we can obtain temperature data through the demodulator. The temperature data was processed by the Origin to draw diagram time-temperature curve. The results show that the measured temperature data of the fiber Bragg grating can meet the requirements of experiment.

[Research on detecting explosive content of 2, 4-dimitroanisole based on THz spectroscopy].

In order to detect the content of a new kind of insensitive melting-cast explosive (DNAN), the system detected the THz characteristics wavelength of DNAN, and solved the content of DNAN by the Bill-Lambert law. Time coherent THz spectroscopy detection system was designed, in which the master system controlled stepper motor to get the micro-scanning of the photoelectric detector. The system parameters were calculated and derived for solving the content of DNAN, and THz characteristic spectrum of DNAN was obtained. Experiment used three methods to detect explosives samples with different content of DNAN, and the results show that the accuracy of this system is close to that of MINI-Z terahertz spectrometer currently broadly applied in THz spectroscopy detection equipment at home and abroad. On this basis, the optimization algorithm of characteristic absorption peak was designed, and by the origin software simulation analysis, it shows that the algorithm can further improve accuracy and stability of the detection system.

Compact terahertz wave polarizing beam splitter.

We designed a compact terahertz (THz) wave polarizing beam splitter based on a periodic bilayer structure, which operates over a wide THz wavelength range. Within a short length (about 1 mm), this polarizing beam splitter separates THz wave TE- and TM-polarized modes into orthogonal output waveguides. Results of simulations with the finite-element method show that 99.99% of the TE-polarized THz wave is deflected by the periodic bilayer structure (with 39.9 dB extinction ratio), whereas 99.58% of the TM-polarized THz wave propagates through the structure (with a 23.7 dB extinction ratio). Tolerance analysis reveals a large tolerance to fabrication errors.

Feasibility of terahertz imaging for discrimination of human hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide, and novel methods for early/rapid diagnosis of HCC are needed. Terahertz (THz) spectroscopy is considered to have the potential to distinguish between normal liver tissue and HCC tissue; however, there are few reports on it. We conduct this observational study to explore the feasibility of THz imaging for the diagnosis of HCC. AIM: To evaluate the feasibility of THz for discriminating between HCC and normal liver tissues using fresh tissue specimens obtained from HCC patients who had undergone surgery. METHODS: Normal liver tissue and HCC tissue were cryosectioned into 50 µm-thick slices and placed on cover glass. Two adjacent tissue sections were separated subjected to histopathological examination by hematoxylin and eosin staining or THz transmission examination, and THz images were compared with pathologically mapped images. We determined the typical tumor and normal liver tissue regions by pathological examination; the corresponding areas of adjacent sections were examined by THz transmission. RESULTS: The transmission rate of HCC tissue was 0.15-0.25, and the transmission rate of typical HCC tissue was about 0.2. THz transmittance in normal liver tissue is slightly higher than 0.4, but there were many influencing factors, including the degree of liver cirrhosis, fat components, ice crystals in frozen sections, and apoptosis. CONCLUSION: In conclusion, this study shows that THz imaging can detect HCC tissue. Further research will yield more detailed data of the THz transmission rates of HCC tissue with different degrees of differentiation.

Structural and energetic insight into the interactions between the benzolactam inhibitors and tumor marker HSP90α.

The heat shock protein 90α (HSP90α) provides a promising molecular target for cancer therapy. A series of novel benzolactam inhibitors exhibited distinct inhibitory activity for HSP90α. However, the structural basis for the impact of distinct R1 substituent groups of nine benzolactam inhibitors on HSP90α binding affinities remains unknown. In this study, we carried out molecular docking, molecular dynamics (MD) simulations, and molecular mechanics and generalized Born/surface area (MM-GBSA) binding free energy calculations to address the differences. Molecular docking studies indicated that all nine compounds presented one conformation in the ATP-binding site of HSP90α N-terminal domain. MD simulations and subsequent MM-GBSA calculations revealed that the hydrophobic interactions between all compounds and HSP90α contributed the most to the binding affinity and a good linear correlation was obtained between the calculated and the experimental binding free energies (R=0.88). The per residue decomposition revealed that the most remarkable differences of residue contributions were found in the residues Ala55, Ile96, and Leu107 defining a hydrophobic pocket for the R1 group, consistent with the analysis of binding modes. This study may be helpful for the future design of novel HSP90α inhibitors.