Research on Ground-Based LWIR Hyperspectral Imaging Remote Gas Detection.

The new progress of ground-based long-wave infrared remote sensing is presented, which describes the windowing spatial and temporal modulation Fourier spectroscopy imaging in details. The prototype forms the interference fringes based on the corner-cube of spatial modulation of Michelson interferometer, using cooled long-wave infrared photovoltaic staring FPA (focal plane array) detector. The LWIR hyperspectral imaging is achieved by the process of collection, reorganization, correction, apodization, FFT etc. from data cube. Noise equivalent spectral radiance (NESR), which is the sensitivity index of CHIPED-1 LWIR hyperspectral imaging prototype, can reach 5.6 x 10⁻8 W · (cm⁻¹ · sr · cm²)⁻¹ at single sampling. The data is the same as commercial temporal modulation hyperspectral imaging spectrometer. It can prove the advantage of this technique. This technique still has space to be improved. For instance, spectral response range of CHIPED-1 LWIR hyperspectral imaging prototype can reach 11. 5 µm by testing the transmission curve of polypropylene film. In this article, choosing the results of outdoor high-rise and diethyl ether gas experiment as an example, the authors research on the detecting method of 2D distribution chemical gas VOC by infrared hyperspectral imaging. There is no observed diethyl ether gas from the infrared spectral slice of the same wave number in complicated background and low concentration. By doing the difference spectrum, the authors can see the space distribution of diethyl ether gas clearly. Hyperspectral imaging is used in the field of organic gas VOC infrared detection. Relative to wide band infrared imaging, it has some advantages. Such as, it has high sensitivity, the strong anti-interference ability, identify the variety, and so on.

[A New Method for Measurement of Laser-Induced Damage Threshold].

With the development of the laser towards high-power and high energy, laser-induced damage threshold of optics becomes one of the important parameters to evaluate the laser damage resistance of optics. Therefore, accurately measuring of the laser-induced damage threshold optics become the focal point studied. And the key to accurately measuring of the laser-induced damage threshold is whether the laser-induced damage can be accurately identified when it occurs. In order to solve low accuracy, long testing time, narrow scope of applications and complex operation of the common damage identification methods, a new testing method to diagnose the laser-induced damage of optics, called plasma diagnosis, is proposed in this paper. Based on this new method, the testing platform was set up, and the spectrum obtained by fiber spectrometer was analyzed under laser radiation by different laser energies. Take whether the spectral lines of the feature element contained in the measured optics occur as standard. The laser-induced damage threshold of K9 glass has been tested, and the test result was compared to that measured by the plasma flash method and the microscope method. The results show that, the plasma diagnosis method proposed in this paper has high-accurate judgment, high- testing speed, simple testing equipment, and easy to realization, which can greatly improve the testing efficiency of the laser-induced damage threshold of optics.

Clustering of low usage codons in the translation initiation region of hepatitis C virus.

The adaptation of the overall codon usage pattern of hepatitis C virus (HCV) to that of human is estimated by the synonymous codon usage value (RSCU). The synonymous codon usage biases for the translation initiation region (TIR) of this virus are also analyzed by calculation of usage fluctuation of each synonymous codon along the TIR (the first 30 codon sites of the whole coding sequence of HCV). As for the overall codon usage pattern of HCV, this virus has a significant tendency to delete the codons with CpG or TpA dinucleotides. Turning to the adaptation of the overall codon usage of HCV to that of human, over half part of codons has a similar usage pattern between this virus and human, suggesting that the host cellular environment of the overall codon usage pattern influences the formation of codon usage for HCV. In addition, there is no obvious phenomenon that the codons with relatively low energy tend to be highly selected in the TIR of HCV, suggesting that the synonymous codon usage patterns for the TIR of HCV might be not affected by the secondary structure of nucleotide sequence, however, the formation of synonymous codons usage in the TIR of HCV is influenced by the overall codon usage patterns of human to some degree.

Mapping codon usage of the translation initiation region in porcine reproductive and respiratory syndrome virus genome.

BACKGROUND: Porcine reproductive and respitatory syndrome virus (PRRSV) is a recently emerged pathogen and severely affects swine populations worldwide. The replication of PRRSV is tightly controlled by viral gene expression and the codon usage of translation initiation region within each gene could potentially regulate the translation rate. Therefore, a better understanding of the codon usage pattern of the initiation translation region would shed light on the regulation of PRRSV gene expression. RESULTS: In this study, the codon usage in the translation initiation region and in the whole coding sequence was compared in PRRSV ORF1a and ORFs2-7. To investigate the potential role of codon usage in affecting the translation initiation rate, we established a codon usage model for PRRSV translation initiation region. We observed that some non-preferential codons are preferentially used in the translation initiation region in particular ORFs. Although some positions vary with codons, they intend to use codons with negative CUB. Furthermore, our model of codon usage showed that the conserved pattern of CUB is not directly consensus with the conserved sequence, but shaped under the translation selection. CONCLUSIONS: The non-variation pattern with negative CUB in the PRRSV translation initiation region scanned by ribosomes is considered the rate-limiting step in the translation process.