Molecular characterization, antibacterial and immunoregulatory activities of liver-expressed antimicrobial peptide 2 in black rockfish, Sebastes schlegelii.

LEAP2 (liver expression antimicrobial peptide 2), is an antimicrobial peptide widely found in vertebrates and mainly expressed in liver. LEAP2 plays a vital role in host innate immunity. In teleosts, a number of LEAP2 homologs have been reported, but their in vivo effects on host defense are still limited. In this study, a LEAP2 homolog (SsLEAP2) was identified from black rockfish, Sebastes schlegelii, and its structure, expression as well as biological functions were analyzed. The results showed that the open reading frame of SsLEAP2 is 300 bp, with a 5'- untranslated region (UTR) of 375 bp and a 3' - UTR of 238 bp. The deduced amino acid sequence of SsLEAP2 shares the highest overall identity (96.97%) with LEAP2 of Sebastes umbrosus. SsLEAP2 possesses conserved LEAP2 features, including a signal peptide sequence, a prodomain and a mature peptide, in which four well-conserved cysteines formed two intrachain disulphide domain. The expression of SsLEAP2 was highest in liver and could be induced by experimental infection with Listonella anguillarum, Edwardsiealla piscicida and Rock bream iridovirus C1 (RBIV-C1). Recombinant SsLEAP2 (rSsLEAP2) purified from Escherichia coli was able to bind with various Gram-positive and Gram-negative bacteria. Further analysis showed that rSsLEAP2 could enhance the respiratory burst activity, and induce the expression of immune genes including interleukin 1-ß (IL-1ß) and serum amyloid A (SAA) in macrophages; additionally, rSsLEAP2 could also promote the proliferation and chemotactic of peripheral blood lymphocytes (PBLs). In vivo experiments indicated that overexpression of SsLEAP2 could inhibit bacterial infection, and increase the expression level of immune genes including IL-1ß, tumor necrosis factor ligand superfamily member 13B (TNF13B) and haptoglobin (HP); conversely, knock down of SsLEAP2 promoted bacterial infection and decreased the expression level of above genes. Taken together, these results suggest that SsLEAP2 is a novel LEAP2 homolog that possesses apparent antibacterial activity and immunoregulatory property, thus plays a critical role in host defense against pathogens invasion.

[Pseudo-targeted metabolomics for differential components of Rhei Radix et Rhizoma from three plant species].

Rhei Radix et Rhizoma is common traditional Chinese medicine with multiple original plants. The content and proportion of the active components in Rhei Radix et Rhizoma from different plant species were compared to accurately evaluate the medicine qua-lity and provide a theoretical basis for precise use of this medicine in clinical practice. In this study, fresh Rhei Radix et Rhizoma samples were collected from the four-year-old plants of Rheum palmatum, R. tanguticum, and R. officinale. The relative content of 220 anthraquinones, anthrones, and tannins in the samples were determined by pseudo-targeted metabolomics, and the differential components were screened by multivariate statistical methods. The principal component analysis classified the samples into three clusters according to the original plants. The orthogonal partial least squares-discriminant analysis(OPLS-DA) screened out 117 differential components, including 8 free anthraquinones, 18 anthraquinone glycosides, 80 anthrones, and 11 tannins. Twenty-eight components had the highest content in R. tanguticum, mainly including sennosides, anthraquinone glycosides, and procyanidins. Thirty-five components showed the highest content in R. officinale, mainly including free anthraquinones and catechines. Fifty-four components showed the highest content in R. palmatum, mainly including dianthrones, while the structures of most of them cannot be determined temporarily. The content distribution of differential components in the three original plants indicates that R. tanguticum has the strongest effect of purging, while R. officinale has the strongest effect of clearing heat and purging fire, and both have stronger effects of resolvong stasis and dredging meridians than R. palmatum.

Identification, expression pattern and functional characterization of IFN-γ involved in activating JAK-STAT pathway in Sebastes schlegeli.

IFN-γ (interferon gamma) is a critical cytokine in the immune system involved both directly and indirectly in antiviral activity, stimulation of bactericidal activity, antigen presentation and activation of macrophages via the Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway. The IFN-γ function is best described in cell defense against intracellular pathogens in mammals, but IFN-γ cytokine-induced metabolic change and its role in anti-infection remain unknown in teleost fish. In this study, a novel IFN-γ (SsIFN-γ) was identified from black rockfish (Sebastes schlegeli) by rapid amplification of cDNA ends (RACE). The open reading frame (ORF) of SsIFN-γ encoded a putative protein of 215 amino acids and shares 60.2%-93.5% overall sequence identities with other teleost IFN-γ. SsIFN-γ was distributed ubiquitously in all the detected tissues and immune cells, which was highly expressed in the spleen, gills, head kidney by quantitative real-time PCR. The mRNA expression of SsIFN-γ was significantly upregulated in the spleen, head kidney, head kidney (HK) macrophages and peripheral blood lymphocytes (PBLs) during pathogen infection. Meanwhile, the recombinant protein (rSsIFN-γ) exhibited an immunomodulatory function to enhance respiratory burst activity and nitric oxide response of HK macrophages. Furthermore, rSsIFN-γ could effectively upregulate the expression of macrophage proinflammatory cytokine, the expression of JAK-STAT signaling pathway related genes and interferon-related downstream genes in the head kidney and spleen. Luciferase assays showed ISRE and GAS activity were obviously enhanced after rSsIFN-γ treatment. These results indicated that SsIFN-γ possessed apparent immunoregulatory properties and played a role in fighting pathogen infection which will be helpful to further understanding of the immunologic mechanism of teleosts IFN-γ in innate immunity.

NKHs27, a sevenband grouper NK-Lysin peptide that possesses immunoregulatory and antimicrobial activity.

As an effective and broad-spectrum antimicrobial peptide, NK-Lysin is attracted more and more attention at present. However, the functions and action mechanism of NK-Lysin peptides are still not comprehensive enough at present. In this study, a sevenband grouper (Hyporthodus septemfasciatus) NK-Lysin peptide, NKHs27, was identified and synthesized, and its biological functions were studied. The results indicated that NKHs27 shares 44.44%∼88.89% overall sequence identities with other teleost NK-Lysin peptides. The following antibacterial activity assay exhibited that NKHs27 was active against both Gram-negative and Gram-positive bacteria, including Staphylococcus aureus, Listonella anguillarum, Vibrio parahaemolyticus and Vibrio vulnificus. Additionally, NKHs27 showed a synergistic effect when it was combined with rifampicin or erythromycin. In the process of interaction with the L. anguillarum cells, NKHs27 changed the cell membrane permeability and retained its morphological integrity, then penetrated into the cytoplasm to act on genomic DNA or total RNA. Then, in vitro studies showed that NKHs27 could enhance the respiratory burst ability of macrophages and upregulate immune-related genes expression in it. Moreover, NKHs27 incubation improved the proliferation of peripheral blood leukocytes significantly. Finally, in vivo studies showed that administration of NKHs27 prior to bacterial infection significantly reduced pathogen dissemination and replication in tissues. In summary, these results provide new insights into the function of NK-Lysin peptides in teleost and support that NKHs27, as a novel broad-spectrum antibacterial peptide, has potential applications in aquaculture against pathogenic infections.

Antimicrobial and immunoregulatory activities of the derived peptide of a natural killer lysin from black rockfish (Sebastes schlegelii).

Natural killer lysin (NK-lysin) is a small molecule antimicrobial peptide secreted by natural killer cells and T lymphocytes. In this study, we characterized a cDNA sequence encoding an NK-lysin homologue (SsNKL1) from black rockfish, Sebastes schlegelii. The open reading frame (ORF) of SsNKL1 encodes a putative protein of 149 amino acids and shares 44%-87% overall sequence identities with other teleost NK-lysins. SsNKL1 possesses conserved NK-lysin family features, including a signal sequence and a surfactant-associated protein B (SapB) domain, sequence analysis revealed that SsNKL1 is most closely related to false kelpfish (Sebastiscus marmoratus) NK-lysin (with 87% sequence identity). SsNKL1 transcripts were detected in all the tested tissues, with the highest level in the kidney, followed by the spleen and gills. Upon Listonella anguillarum infection, the mRNA expression of SsNKL1 in the black rockfish was significantly up-regulated in the liver and kidney. The derived peptide SsNKLP27 from SsNKL1 was synthesized, and its biological function was studied. SsNKLP27 showed direct antibacterial activity against Gram-negative and Gram-positive bacteria, including Staphylococcus aureus, Bacillus subtilis, L. anguillarum, Vibrio parahaemolyticus, Vibrio alginolyticus and Vibrio vulnificus. SsNKLP27 treatment facilitated the bactericidal process of erythromycin by enhancing the permeability of the outer membrane. In the process of interaction with the target bacterial cells, SsNKLP27 changed the permeability and retained the morphological integrity of the cell membrane, then penetrated into the cytoplasm, and induced the degradation of genomic DNA and total RNA. In vivo studies showed that administration of SsNKLP27 before bacterial and viral infection significantly reduced the transmission and replication of pathogens in tissues. In vitro analysis showed that SsNKLP27 could enhance the respiratory burst ability and regulate the expression of some immune-related genes of macrophages. In summary, these results provided new insights into the function of NK-lysins in teleost fish and support that SsNKLP27 is a new broad-spectrum antimicrobial peptide that has a potential application prospect in aquaculture against pathogenic infection.

Nitric oxide detection using principal component analysis spectral structure matching to the UV derivative spectrum.

Ultraviolet (UV) spectroscopy is widely applied in real-time environmental monitoring, especially in diesel vehicle nitrogen monoxide (NO) emissions. However, in field experiments, UV absorption spectrum may exist for different degrees of drifts. Spectral jitters may exist for various reasons such as optical power variation, electrical signal drift, and the refractive index jitters of the optical path for an extended period of time, which causes the detection system to be calibrated. And the pulse xenon lamps as the UV source are characterized by specific emission lines that interfere in spectral analysis directly. For these problems, we proposed the spectral structure matching method based on principal component analysis (PCA), which was compared with the conventional polynomial fitting method to observe feasibility and variability. Further, the UV derivative spectrum was applied to the system appropriately, due to the variation of the absorption peak, and was only related to the target gas by using the above method. We validated our method experimentally by performing the NO UV detection system with the calibration and the comparison test. The results suggested that the calibration relative error was less than 9% and the measurement relative error was less than 6% for this wide range by the proposed processes, which optimized the interference of spectral structures and fluctuation to the system and therefore provided better monitoring. This study may provide an alternative spectral analysis method that is unaffected on the specific emission lines of lamps and is not limited to the spectral region and the target gas.

Analysis of factors influencing cervical lymph node metastasis of papillary thyroid carcinoma at each lateral level.

OBJECTIVE: To analyze the clinicopathological characteristics of patients with papillary thyroid carcinoma (PTC) and its influence on the distribution of lymph node metastasis at each lateral level of the neck to guide precise treatment of the lateral area. METHODS: The clinicopathological data of patients with PTC initially diagnosed and treated at our hospital from February 2014 to September 2021 were collected; the metastatic status of each lateral level was recorded, and correlations were analyzed. RESULTS: A total of 203 patients were enrolled in this study. There were 67 males and 136 females, with an average age of 41.1 years. In the lateral cervical area, lymph node metastasis was found at level IIa in 81 patients (39.9%); level III, 171 patients (84.2%); level IV, 122 patients (60%); and level Vb, 18 patients (8.9%). Correlation analysis showed that age (r = 0.198, P < 0.01) and sex (r = 0.196, P < 0.01) were weakly correlated with the number of positive lymph nodes in the central region. The tumor size (r = 0.164, P < 0.05) was weakly correlated with lymph node metastasis at level IV. The presence of multiple tumor foci was weakly correlated with lymph node metastasis at level IIa (r = 0.163, P < 0.05) and Vb (r = 0.143, P < 0.05). The tumor location (r = - 0.168, P < 0.05) was weakly correlated with lymph node metastasis at level III. The number of positive lymph nodes in the central region (r = 0.189, P < 0.01) was weakly correlated with lymph node metastasis at level IV. Binary logistic regression analysis showed that the risk of metastasis of multifocal tumors was higher than that of unifocal tumors by 1.958 times at level IIa (P = 0.021, OR = 1.958) and 2.929 times at level Vb (P = 0.049, OR = 2.929). The higher the tumor was located, the higher the risk of metastasis at level III (P = 0.014, OR = 0.563). Every additional positive lymph node in the central region increased the risk of metastasis at level IV by 1.126 times (P = 0.009, OR = 1.126). CONCLUSIONS: For patients with pathological evidence of lateral metastasis, standard dissection of level IIa through Vb is recommended; selective dissection requires careful consideration. Patients with multifocal tumors have a high risk of metastasis at levels IIa and Vb, which requires special attention during the operation.

Nanometal Oxides with Special Surface Physicochemical Properties to Promote Electrochemical Detection of Heavy Metal Ions.

Heavy metal ions (HMIs) are one of the major environmental pollution problems currently faced. To monitor and control HMIs, rapid and reliable detection is required. Electrochemical analysis is one of the promising methods for on-site detection and monitoring due to high sensitivity, short response time, etc. Recently, nanometal oxides with special surface physicochemical properties have been widely used as electrode modifiers to enhance sensitivity and selectivity for HMIs detection. In this work, recent advances in the electrochemical detection of HMIs using nanometal oxides, which are attributed to specific crystal facets and phases, surficial defects and vacancies, and oxidation state cycle, are comprehensively summarized and discussed in aspects of synthesis, characterization, electroanalysis application, and mechanism. Moreover, the challenges and opportunities for the development and application of nanometal oxides with functional surface physicochemical properties in electrochemical determination of HMIs are presented.

Identifying Phase-Dependent Electrochemical Stripping Performance of FeOOH Nanorod: Evidence from Kinetic Simulation and Analyte-Material Interactions.

Metal hydroxide nanomaterials are widely applied in the energy and environment fields. The electrochemical performance of such materials is strongly dependent on their crystal phases. However, as there are always multiple factors relating to the phase-dependent electrochemistry, it is still difficult to identify the determining one. The well-defined crystal phases of α- and ß-FeOOH nanorods are characterized through the transmission electron microscopy by a series of rotation toward one rod, where the cross-section shape and the growth direction along the [001] crystalline are first verified for 1D FeOOH nanostructures. The electrosensitivity of the two materials toward Pb(II) is tested, where α-FeOOH performs an outstanding sensitivity whilst it is only modest for ß-FeOOH. Experiments via Fourier transform infrared spectroscopy, X-ray absorption fine structure (XAFS), etc., show that α-FeOOH presents a larger Pb(II) adsorption capacity due to more surficial hydroxyl groups and weaker PbO bond strength. The reaction kinetics are simulated and the adsorption capacity is found to be the determining factor for the distinct Pb(II) sensitivities. Combining experiment with simulation, this work reveals the physical insights of the phase-dependent electrochemistry for FeOOH and provides guidelines for the functional application of metal hydroxide nanomaterials.

Study on Recognition of Cooking Oil Fume by Fourier Transform Infrared Spectroscopy Based on Artificial Neural Network.

With the developing of catering trade, cooking oil fume has became one of the three major air pollution sources in some cities. In recent years, a lot of research on the cooking oil fume have been done for its high threaten to human health. The cooking oil fume contains a large amount of unsaturated hydrocarbons produced by pyrolysis of edible oil, which are harmful to human health. The characteristics of the composition and content of edible oil fumes produced by pyrolysis of different edible oil are different. For classification and identification of edible oil, two kinds of classification and identification mathematical model are constructed. The spectrum data of different edible oil fume are collected by Fourier transform infrared spectrometer which is independent research and development. At the same time, different classification algorithms of the principal component analysis (PCA) combining probabilistic neural network (PNN) and the error back propagation artificial neural network (BPANN) are constructed respectively. Two kinds of classification algorithms are used to analyze the Fourier transform infrared spectrum data of different cooking fume gas. The mathematical models are trained by the sample data, and the trained mathematical model are used to analyze the unknown spectral data to determine the type of edible oil. The experimental results show that the two algorithms can classify and identify different types of oil fume. In the whole band recognition, the recognition rate is 90.25% and 97% respectively. By analyzed spectral data of flue gas absorption band, spectrums of atmospheric window and the strong absorption feature bands of volatile organic compounds (VOCs) (from 1 300 to 700 cm-1 and from 3 000 to 2 600 cm-1) were extracted. The absorbance data are divided into two parts with separated absorption band, and the two algorithms in 3 000～2 600 cm-1 band have better recognition rate. PCA-PNN algorithm recognition rate is 90.25% and PCA-BPANN algorithm recognition rate is 92.25%. Obviously, two kinds of artificial neural network algorithm combining principle component analysis respectively can effectively identify the types of edible oil fume.

Study on Hydrogen Fluoride at High Temperature Detection Method with Temperature Correction Based on Laser Technology.

Hydrogen fluoride(HF) is one of the important character gases for fault diagnosis of gas insulation switch (GIS) in the system of substation equipment. The high-accuracy, fast- response and real-time detection method of HF is a focus in industrial and environmental fields. In this research, the HF detection experiment system was set up at first based on laser absorption spectroscopy technology combined with anti-corrosion multiple reflection cell made by monel steel. Moreover, the laser absorption spectral characteristics of HF at different temperature were analyzed, then the coefficient partition function curve and absorption linestrength curve according to the distribution function coefficient in HITRAN database were studied. As the most important work, the concentration inversion algorithm was designed here with HF character spectrum analysis and temperature parameter correction method for accurate concentration inversion after the basic study. At last, the continuous experimental results were obtained by HF sample gases of different concentration considerating the temperature characteristic of the multiple reflection cell. When the multiple reflection cell was heat and stay stably, the biggest detection error of concentration inversion was 5.33% and 5.87% at 313 and 323 K respectively without temperature correction, and that was 1.20% and 1.47% respectively after temperature correction. By continuous detection and culculation, the detection limit is 8.7×10-5 mmol·mol-1 at 323 K which is a little higher than 6.3×10-5 mmol·mol-1 at 290 K(20 m optical length). Although the detection error with temperature correction at high temperature was higher than it at room temperature, the results show that it was lower than that without correction at the same temperature. It was verified that the this spectrum detection method and concentration inversion algorithm works stably and reliably, so this technology could realize HF real-time monitoring demand in chemical production field and it will provide the effective technical support in gas emission regulation in safety and environment protection for our country.

[Rapid Soil Classification with Laser Induced Breakdown Spectroscopy].

Soil classification is an important research content in soil science field. It is the basis of soil survey and resource evaluation which is important to agricultural production. There are many soil classification standards all over the world. China has two kinds of classifications including soil genetic classification and soil system classification. There are great differences between different types of soil elements, so it is feasible for soil classification to use laser induced breakdown spectroscopy. Laser induced breakdown spectroscopy (LIBS) is a new element analysis technology which uses a laser pulse with high energy density to ablate samples. LIBS has been used in many fields including environmental protection and industrial production control. It can directly reflect the difference of element content in different soils. The experimental setup including an Nd: YAG laser, a spectrometer, a computer and a rotating platform. In the experiment 7 kinds of soil (red soil, brick red soil, lateritic red soil, paddy soil, cinnamon, alluvial soil and alpine meadow soil) including 25 samples were used. All soil samples were grinded and sieved before the experiment. Under the same experimental condition, the temperatures of the plasma created by the laser pulses on the surface of the different soil samples have great differences. The lateritic red soil had the highest temperature, and the alpine meadow soil had the lowest. But it was not enough to form the basis for classification. Therefore six constant elements including Si, Fe, Al, Mg, Ca and Ti were selected and their spectral line intensity were treated as classification index. Principal component analysis (PCA) was used to simplify the classification process. The PCA method could simplify the 6 indexes to few independent indexes which could also reflect the spectral information of the 6 elements. The original spectral data was processed by Matlab. The process consisted of spectral background removal, characteristic spectrum identify and extraction. The classification results showed a three--dimensional figure. Except alpine meadow soil which varied in element concentrations 6 kinds of soils achieved good classification. The brick red soil and lateritic red soil varied in PC1, but their PC2s and PC3s were the same. The two kinds of soil overlapped with each other and they couldn't be separated. Back-propagation artificial network was also used to achieve soil classification. The classification results were the same with the PCA. Some brick red soil and lateritic red soil samples were identified inaccurately. When the PC1, 2, 3 were used as the input of the BP-neural network, the classification had much better accuracy because less input improved the performance of the BP-neural network. Only one alpine meadow soil sample was identified to cinnamon soil. When the plasma temperature was also taken into account, all the soil samples could be distinguished. The results showed that LIBS could be used to classify soils based on their element content differences. The PCA, soil plasma temperature and BP-neural network were useful tools to achieve soil classification. The LIBS provides a useful tool for general detailed soil survey and rational utilization of soil.

[Comparative Study on Laser Induced Breakdown Spectroscopy Based on Single Pulse and Re-Heating Orthogonal Dual Pulse].

In order to improve the detection sensitivity and spectral characteristic of laser-induced breakdown spectroscopy (LIBS), re-heating orthogonal dual-pulse configuration is adopted to analyze Fe, Pb, Ca and Mg contained in the sample and soil sample contained different concentrations of heavy mental Cr. Variation relationship between spectral intensity, signal-to-background(SBR) of four characteristic spectral lines FeⅠ：404.581 nm，PbⅠ：405.78 nm，CaⅠ：422.67 nm and MgⅠ：518.361 nm and time interval of two laser pulses is discussed, the best time interval of two laser pulses is obtained 1.0 µs. In the condition of single pulse and dual-pulse, the enhancement factor of spectral intensity of four characteristic spectral lines FeⅠ：404.581 nm，PbⅠ：405.78 nm，CaⅠ：422.67 nm and MgⅠ：518.361 nm is respectively 2.23，2.31，2.42 and 2.10; The time evolution characteristic of spectral intensity of characteristic spectral lines FeⅠ：404.581 nm and CaⅠ：422.67 nm is considered, and also the variation relationship between spectral acquisition delay time and SBR of four characteristic spectral lines, dual-pulse can prolong decay time of spectral intensity and improve the SBR of characteristic spectral lines; time evolution characteristic of plasma temperature and electron density is compared in the condition of single pulse and dual-pulse, maximum elevation of plasma temperature is found to be 730 K, and the maximum increase of electron density is 1.8×1016 cm-3. The limits of detection of heavy mental Cr are obtained 38 and 20 µg·g-1 respectively in condition of single and double pulse, limit of detection of Cr is reduced approximately 2 times by the condition of re-heating orthogonal dual pulse. Results above indicate that re-heating orthogonal dual-pulse can improve detection sensibility and spectral characteristic of LIBS technique, which provides an effective method for decreasing the limit of detection of elements.

Study on Detection Sensitivity of Heavy Metal in Water Based on LIBS Combined with Electrode Enrichment Method.

In order to improve the detection sensitivity of laser-induced breakdown spectroscopy (LIBS) and lower the limit of the detection of elements, LIBS combined with Aluminum electrode enrichment method is adopted to analyze heavy metals such as Pb,Cdand Ni in the water. The relationship between the characteristic spectral intensity and the key parameters-voltage of electrode method is discussed, the spectral intensity increases first and then decreases with the increase of voltage. The spectral intensity reaches the maximum value when the enrichment voltage is 1.2 V while the optimal enrichment voltage value is 1.2 V. The stability of characteristic spectral lines of heavy metals is studied, and the relative standard deviation(RSD) of spectral intensity of Pb, Cd and Ni is 5.98％，4.25 ％ and 5.27％ respectively, the result shows that the spectral line obtained by this method has high stability. A series of samples in the range of 0~0.13 mg·L-1 are prepared and quantitatively analyzed, the limit of detection of Pb, Cd and Ni is obtained 1.2，3.1 and 1.7 ppb respectively. The above result shows that LIBS combined with aluminum electrode enrichment method can effectively improve the stability of characteristic spectral lines and lower the limit of detection of Pb,Cd and Ni. This research also provides a method to further improve detection sensitivity of LIBS and analysis ability of heavy metal in the water.

[Quality Optimization Method for Ambient CO(2) Inversion of High Resolution Fourier Transform Infrared Spectrum].

CO(2) retrievals with high quality facilitate resolving the sources and sinks of CO(2) are helpful in predicting the trend in climate change and understanding the global carbon cycle. Based on a nonlinear least squares spectral fitting algorithm, we investigate the optimization method for CO2 products derived from ground-based high resolution Fourier transform infrared spectra. The CO(2) vertical column densities (VCDs) are converted into column-averaged dry air mole fraction XCO(2) by using the fitted O(2) VCDs, and thus the system errors (e. g. pointing errors, ILS errors, zero-level offset) are corrected greatly. The virtual daily variation which is related to air mass factor is corrected with an empirical model. The spectra screening rule proposed in this paper can greatly improve the XCO2 quality. The CO(2) retrievals before and after the optimized method are compared using a typical CO(2) daily time series. After using the optimized method, the fitting error is reduced by 60%, and the two-hours-averaged precision is ~0.071% (equals to ~0.28 ppm), which is perfectly in line with the TCCON (the total carbon column observing network) threshold, i. e., less than 0.1%.

[Rapid Quantitative Detection of Bacterial in Water Based on Multi-Wavelength Scattering Spectra].

The structures of bacterial cells are analyzed in this paper. The scattering components of individual cell were divided into two parts including external structure and internal structure. The interpretation model of bacteria about scattering light is established. The model is used to analyze the scattering light of Escherichia coli in the region of 400~900 nm. The average size of external structure and the internal structure can be obtained, and the ratio of the two parts is also obtained. According to the relationship of the optical density of single cell and the overall measurement, the concentration of bacterial can be obtained quickly. The maximum difference in all the concentrations of the bacteria repeated measurements is 1.83%; compared with the plate culture method, the measurement results were in the same order of magnitude, with relative error of 3.43%. The scattering light of Escherichia coli and Klebsiella pneumoniae are analyzed in different growth stages, the curves of the concentration and the size of the two species bacteria over time are obtained. The results can provide a quick way for the study of bacterial growth and technical support for rapid detection of bacteria in the water.

[Bidirectional Reflectance Distribution Function of Space-Borne Quartz Volume Diffuser].

Quartz Volume Diffuser(QVD) is used in the observing system of Space-Borne differential optical absorption spectrometer. The precision of observed solar spectrum directly influences the accuracy of the gas retrievals. Therefore the QVD is required for well Lambert feature to ensure the accuracy of full field solar spectrum, and it can provide uniformity source in the observing view of the instrument. Using bidirectional reflectance distribution function(BRDF) measurement instrument, adopting the powder pressboard of F4(polytetrafluoroethylene(PTFE)), QVD's BRDF is measured by choosing the relative measurement method. Four kinds of QVD's BRDF is obtained in the range of 180～880 nm, the observing view of -70°ï½ž+70°. Two kinds of QVD which has a well Lambert feature are selected by analyzing the QVD's BRDF. The diffuse sunlight measured by QVD and F4 is compared, which show that QVD has well scattering properties with regard to solar spectrum and can be selected as the measuring diffuser. That supports for next Ultraviolet irradiation measurement, atomic oxygen erosion measurement and comparison measurement.

[The Detection of Atmospheric HONO and NO2 with Fiber Coupling Long-Path Differential Optical Absorption Spectroscopy System].

A new type of fiber coupling Long-Path Differential Optical Absorption Spectroscopy System(LP-DOAS) based on schmidt - cassegrain telescope was introduced in detail in this paper and it was applied to the accurate measurement of the actual atmospheric HONO and NO2. This measuring system simplified the structure of traditional LP-DOAS system, combining with the design of optical fiber coupling.It made full use of the telescope primary mirror's effective area. The effects of the offset, dark current and telescope stray light to the new LP-DOAS system were discussed in this paper; On a clear day, the ratio between telescope stray light and the optical intensities was less than 1%. To verify the accurate of the new LP-DOAS system, the atmospheric NO2 were simultaneously measured with the new LP-DOAS system and traditional LP-DOAS system. The correlation coefficient R2 was up to 0.968. The observation of atmospheric HONO was carried out by using the fiber coupling LP-DOAS in Gucheng, Hebei Province, China, and the detection limit (2σ) of HONO and NO2 was 84.2 and 144.6 ppt , respectively, with 2 490 m path length and the average time resolution of about 30 s. In the whole measurement in Gucheng, the maximum of HONO and NO2 were 3.2 and 37.8 ppb, respectively, and the minimum were both under the detection limits; the ratio of HONO/NO2 at night was calculated.

[Study of the Impact of Sample Thickness on Thin Film Method X-Ray Fluorescence Spectrum Measurement].

The mixed samples of nylon film enrichment of Cr, Pb and Cd three elements and glass fiber membrane filter were as the research object. With the method of superposition of membrane filter, the XRF spectra were measured under different thin film samples thicknesses. According the changes of characteristic XRF of Cr, Pb and Cd elements in the mixed sample and Ca, As and Sr elements in glass fiber membranes, the effects of sample thickness on thin film method XRF spectrum measurement were studied. The study results showed that the effects of thin film sample thickness on the fluorescent properties of elements with characteristic spectral lines in different energy ranges were different. The energy of characteristic spectral lines was greater, the loss of element characteristic X-ray fluorescence when it passed through membrane and reached detector was less. But matrix effect caused by thin film sample thickness increase was stronger with the energy of characteristic spectral lines greater. The background fluorescent intensity in corresponding characteristic spectral line location was greater. So the impact of matrix effect caused by sample thickness increase on thin film method XRF spectrum measurement sensitivity was greater. For elements with low energy characteristic spectral lines (energy≤7 keV), the way of increasing thin film sample thickness in order to increase the mass-thickness concentration of component measured, can not effectively improve the sensitivity of thin film method XRF spectrum measurement. And thin film samples thickness within 0.96 mm is conductive to the measurement and analysis of XRF spectrum. For element with higher energy characteristic spectra lines(energy＞7 keV), the sensitivity of XRF spectrum measurement can be appropriately increased by the way of increase thin film sample thickness in order to increase the mass-thickness concentration of component measured. And thin film samples thickness within 0.96～2.24 mm is more conductive to the measurement and analysis of XRF spectrum. The study provides an important theoretical basis for thin sample preparation and enrichment technology of thin film method X-ray fluorescence spectrum analysis the atmosphere and water heavy metal.

[An Incoherent Broadband Optical Cavity Spectroscopy for Measuring Weak Absorption Cross Section of Sulfur Dioxide].

As a highly sensitive detection technology, incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) have successfully measured a variety of trace gases. According to the principle of cavity enhanced absorption spectroscopy, if the accurate concentration of the target gas, the curve of the mirror reflectance, effective absorption path length, the light intensity of the absorbing gas and non-absorbing gas are known, the absorption cross section of the absorption gas can be measured. The accurate measurements of absorption cross section are necessary for satellite retrievals of atmospheric trace gases and the atmospheric research. This paper describes an incoherent broadband cavity enhanced absorption spectroscopy(IBBCEAS) instrument with 365 nm LED as the light source for measuring absorption cross section of SO2 from 357 to 385 nm which is arising from the spin-forbidden a ³B1--X¹A1 transition. In comparison to the literature absorption cross section of SO2, and correlation coefficient r is 0.997 3. The result shows the potential of the IBBCEAS system for measuring weak absorption cross section.