[Quantitative Analysis of Heavy Metals in Water with LIBS Based on Signal-to-Background Ratio].

There are many influence factors in the precision and accuracy of the quantitative analysis with LIBS technology. According to approximately the same characteristics trend of background spectrum and characteristic spectrum along with the change of temperature through in-depth analysis, signal-to-background ratio (S/B) measurement and regression analysis could compensate the spectral line intensity changes caused by system parameters such as laser power, spectral efficiency of receiving. Because the measurement dates were limited and nonlinear, we used support vector machine (SVM) for regression algorithm. The experimental results showed that the method could improve the stability and the accuracy of quantitative analysis of LIBS, and the relative standard deviation and average relative error of test set respectively were 4.7% and 9.5%. Data fitting method based on signal-to-background ratio(S/B) is Less susceptible to matrix elements and background spectrum etc, and provides data processing reference for real-time online LIBS quantitative analysis technology.

[The research on separating and extracting overlapping spectral feature lines in LIBS using damped least squares method].

In recent years, the technology of laser induced breakdown spectroscopy has been developed rapidly. As one kind of new material composition detection technology, laser induced breakdown spectroscopy can simultaneously detect multi elements fast and simply without any complex sample preparation and realize field, in-situ material composition detection of the sample to be tested. This kind of technology is very promising in many fields. It is very important to separate, fit and extract spectral feature lines in laser induced breakdown spectroscopy, which is the cornerstone of spectral feature recognition and subsequent elements concentrations inversion research. In order to realize effective separation, fitting and extraction of spectral feature lines in laser induced breakdown spectroscopy, the original parameters for spectral lines fitting before iteration were analyzed and determined. The spectral feature line of' chromium (Cr I : 427.480 nm) in fly ash gathered from a coal-fired power station, which was overlapped with another line(FeI: 427.176 nm), was separated from the other one and extracted by using damped least squares method. Based on Gauss-Newton iteration, damped least squares method adds damping factor to step and adjust step length dynamically according to the feedback information after each iteration, in order to prevent the iteration from diverging and make sure that the iteration could converge fast. Damped least squares method helps to obtain better results of separating, fitting and extracting spectral feature lines and give more accurate intensity values of these spectral feature lines: The spectral feature lines of chromium in samples which contain different concentrations of chromium were separated and extracted. And then, the intensity values of corresponding spectral lines were given by using damped least squares method and least squares method separately. The calibration curves were plotted, which showed the relationship between spectral line intensity values and chromium concentrations in different samples. And then their respective linear correlations were compared. The experimental results showed that the linear correlation of the intensity values of spectral feature lines and the concentrations of chromium in different samples, which was obtained by damped least squares method, was better than that one obtained by least squares method. And therefore, damped least squares method was stable, reliable and suitable for separating, fitting and extracting spectral feature lines in laser induced breakdown spectroscopy.

[Analysis of lead in unknown samples based on the standard addition method using laser induced breakdown spectroscopy].

The standard addition method with laser induced breakdown spectroscopy was used to analyze an unknown sample taken from a lead battery factory. the matrix influence on the results was effectively avoided when the external or internal standard method was used, and the pretreatment of samples was simple and quick. The Nd ' YAG pulse laser with wavelength 1 064 nm was used as the excitation source. The echelle spectroscopy with high resolution and wide spectral range was used as the spectral separation device, and the intensified charge coupled device (ICCD) as the spectral detection device in the experiment. The characteristic line at 405. 78 nrn was chosen as the analysis line to measure Pb concentration. Fe I : 404. 58 line was chosen as the internal standard. Pre-experiment was carried out to confirm the appropriate condition. Under the laser energy of 128. 5 mJ, the delay time of 2. 5 tps, and the gate width of 3 ps, it was determined that with the addition of Pb to the sample in the range of 0 and 25 000 mg . kg-1, there wasn't self-absorption. There was a good linear relationship between the intensity of the spectral line of 405. 78 nm and the addition of Pb. The appropriate concentration of Pb added into the sample for analysis was determined by this series of samples. On this basis, four samples were prepared with three parallel samples for each sample in order to verify the repeatability and reliability of the method, i. e. 5 000, 10 000, 15 000, 20 000 mg . kg-1 Pb was added into the original sample. The results were compared with the result of ICP-MS. The twelve samples' relative errors were between -24. 6% and 17. 6%. The average result was 43 069 mg . kg-1 with the relative error -2. 44%.

[Research on parameter optimization of LIBS used for multi-element measurements in water].

The one of the advantages about Laser Induced Breakdown Spectroscopy (LIBS) is multielement detection at the same time. In order to obtain the optimum signal in the multi-element measurements of water with LIBS, the present paper firstly models the numerical relationship between the signal-to-background ratio of characteristic spectral lines and the delay time and gate width time with BP neural network, using DM design experiment data as the checking sample to ensure the generalization ability of the BP neural network model. Based on the above model, genetic algorithm is used to optimize measurement parameters and the fitness function phi is defined. When the optimum delay time and gate width time is (15.5 micros, 21.5 micros), the minimum value of psi is 0.102 4. The optimization results of genetic algorithm are further confirmed with experimental results. So the method of parameters optimization overall improves S/B of multi-element measurements in water with LBS, and provides the reference for parameter optimization of other experiments.

[The curing behavior of two thermoset resins containing silicon alkynyl group].

In the present report, the curing behavior of two thermoset resins containing silicon alkynyl group- PAR and PMR, and the correlation between the curing structure of resin and their thermal stability were investigated by FTIR, 13C NMR, DSC and TGA techniques. The IR and NMR results showed that the curing mechanism of PAR and PMR resin is different. Based on aromatic cyclization among alkynyl groups and Diels-Alder reaction, aromatic frame network structure constituted by benzene cycles and condensed aromatic cycles are formed in the PAR cured resin. Using additional reaction among Si-H group, alkynyl group and alkenyl group, saturated Si-C(sp3) network structure is formed in the PMR cured resin. The aromatic frame network structure and Si-C(sp3) network structure provide good thermal stability for PAR and PMR resin respectively. The thermal decomposition temperatures Td5 of both resins are above 600 degrees C, and the residues percentages at 900 degrees C are above 85%.

[Distribution, Sources, and Risk Assessment of Microplastics in Surface Sediments of Yellow River Delta Wetland].

Estuarine habitats are a critical zone of the Earth with strong land-sea interactions, that are strongly influenced by human activities. Microplastics (MPs) pollution in the Yellow River Delta (YRD) wetland, a typical young warm-temperate estuarine wetland, has not been comprehensively studied. The morphology, abundance, particle size, and polymer composition of MPs in the surface sediments of the YRD wetland were determined, and the pollution status and ecological risk in the study area were evaluated using the pollution load index (PLI) and potential pollution risk index (PRI). The results showed that the abundance of MPs in the YRD wetland was 20-520 n·kg-1, with a median value of 150 n·kg-1. The MPs were primarily fibers in shape and black in color, with particle size over 1 mm. The polymer components were primarily rayon, polyethylene, polyester, and polyethylene terephthalate. The PLI and PRI values of the MPs in the area were between 0.04-0.96 and 0.00-171.60, respectively, indicating that the pollution of MPs in the YRD wetland was at a slightly polluted level with low ecological risk.

4-(2-{2-[2-(2-Nitro-1H-imidazol-1-yl)ethoxy]eth-oxy}eth-oxy)benzaldehyde.

In the mol-ecule of the title compound, C(16)H(19)N(3)O(6), the imidazole ring is essentially planar [maximum deviation = 0.002 (2) Å] and forms a dihedral angle of 5.08 (14)° with the nitro group. In the crystal structure, adjacent mol-ecules are connected via inter-molecular C-H⋯O hydrogen bonds into columns parallel to the a axis.

Bis(µ-3,5-dinitro-benzoato-κO:O)bis-(µ-3,5-dinitro-benzoato)-κO,O:O;κO:O,O-bis-[(3,5-dinitro-benzoato-κO,O)(1,10-phenanthroline-κN,N)dysprosium(III)].

In the binuclear title complex, [Dy(2)(C(7)H(3)N(2)O(6))(6)(C(12)H(8)N(2))(2)], the Dy(III) ions exhibit a distorted monocapped square-anti-prismatic geometry and are coordinated by seven O atoms of four 3,5-dinitrobenzoate (DNBA) anions and two N atoms of a phenanthroline ligand. The carboxylate groups of the DNBA anions exhibit three coordination modes: bidentate chelating, bidentate chelating-bridging and tridentate chelating-bridging. The center of the mol-ecule is located on a crystallographic center of inversion.

miR-381 Mediates the Development of Head and Neck Squamous Cell Carcinoma via Targeting STC2.

OBJECTIVE: miR-381 is implicated in the occurrence and development of various cancers, yet its role in head and neck squamous cell carcinoma (HNSCC) remains largely unknown. This study sought to research the direct target of miR-381 in HNSCC and investigate their roles in cancer progression. METHODS: miRNA and mRNA expression files of HNSCC were accessed from TCGA database and then processed for differential analysis. Bioinformatics databases were employed to predict the target mRNAs of the potential miRNA. qRT-PCR was conducted to determine the expression levels of the target miRNA and mRNA. Then, a series of in vitro experiments like CCK-8, colony formation assay, wound healing assay and transwell assay were performed to detect cell proliferation, migration and invasion. Dual-luciferase reporter gene assay was carried out for the further validation of the targeted relationship between the miRNA and mRNA. RESULTS: miR-381 was observed to be greatly down-regulated in HNSCC cells, and its overexpression could inhibit cell proliferation, migration and invasion. Besides, dual-luciferase reporter gene assay confirmed that STC2 was a direct target of miR-381, and their expression levels were reversely correlated. Moreover, rescue experiments demonstrated that overexpressing STC2 could rescue the inhibitory effect of miR-381 overexpression on cell proliferation, migration and invasion. Also, we verified that miR-381/STC2 exerted its function on HNSCC proliferation by mediating the FAK/PI3K/Akt/mTOR signaling pathway. CONCLUSION: miR-381 suppresses cell proliferation, migration and invasion in HNSCC through targeting STC2, and participates in HNSCC development probably via the FAK/PI3K/Akt/mTOR signaling pathway.

Comparison of the prognosis of neoadjuvant chemoradiotherapy treatment with surgery alone in esophageal carcinoma: a meta-analysis.

BACKGROUND: Resection remains the best treatment for carcinoma of the esophagus in terms of local control, but local recurrence and distant metastasis remain an issue after surgery. Chemo-radiotherapy (CRT) followed by surgery was associated with significantly improved survival benefit, but the effectiveness of neoadjuvant therapy in patients with resectable esophageal carcinoma remains controversial. The aim of this study was to evaluate the effects of neoadjuvant chemoradiotherapy in resectable esophageal carcinoma compared to surgery alone (SA). METHODS: A search for publications that compared the efficacy of CRT with SA in resectable esophageal carcinoma was conducted. After a rigorous review of the quality, the data were extracted from eligible trials. The major outcomes measures were odds ratios (ORs). The ORs with their corresponding 95% confidence intervals were the principal measure of effects. For the meta-analysis, Revman 5.3 software was used to analyze the combined pooled ORs using fixed- or random-effects models according to the heterogeneity. RESULTS: Our findings revealed that, compared with SA, neoadjuvant CRT was associated with improved overall survival (OS) and progression-free survival times, but the 3- and 5-year OS did not show a statistical difference (P≥0.05). The adjuvant chemotherapy group did not show significant improvement on reference rate and metastasis rate compared with the control group. CONCLUSION: CRT does significantly improve progression-free survival and OS in patients with esophageal cancer compared with SA. However, further assessment is still warranted on the role of CRT in future trials with well-selected patients.

Alkylphenols in surface sediments of the Yellow Sea and East China Sea inner shelf: occurrence, distribution and fate.

Alkylphenols (APs) have been found as ubiquitous environmental pollutants with reproductive and developmental toxicity. In this study, APs in surface sediments of the Yellow Sea (YS) and East China Sea (ECS) inner shelf were analyzed to assess influences of riverine and atmospheric inputs of pollutants on the marine environment. NP concentrations ranged from 349.5 to 1642.8 ng/g (average 890.1 ng/g) in the YS sediments and from 31.3 to 1423.7 ng/g (average 750.1 ng/g) in the ECS inner shelf sediments. NP distribution pattern was mainly controlled by the sedimentary environment. OP concentration was 0.8-9.3 ng/g (average 4.7 ng/g) in the YS sediments and 0.7-11.1 ng/g (average 5.1 ng/g) in the ECS sediments. Assessment of the influence of distances from land on OP concentrations provided evidence for the predominance of coastal riverine and/or atmospheric inputs rather than long-range transport. And the biological pump may play an important role for sequestration of OP in the nearshore area.

Source apportionment of polycyclic aromatic hydrocarbons in surface sediment of mud areas in the East China Sea using diagnostic ratios and factor analysis.

Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHs) have been quantified for surface sediments collected from the East China Sea (ECS). Our results showed that relatively high levels of PAHs and AHs occurred in both the inner and outer mud areas, while their concentrations at the control site were much lower. AHs for all samples were dominated by the unresolved complex mixture (UCM). Results from diagnostic ratios revealed that sedimentary PAHs were mainly originated from mixed combustion residues of biomass, coal, and petroleum. Combustion residues of petroleum and oil were responsible for the presence of high AHs concentrations. We also conducted factor analysis (FA) to further characterize the PAH and AH sources. Four factors were identified based on the loading of components and attributed to coal and wood combustion (Factor 1), traffic-related sources (Factor 2), petrogenic source (Factor 3) and natural gas combustion (Factor 4).

[Effects of storage medium and temperature on short-term storage of Acipenser baerii eggs].

This paper studied the effects of different storage medium (coelomic fluid, Hepes solution, and modified Ringer's solution), temperature (4 degrees C and 16 degrees C), and duration (4 h, 8 h, 16 h, and 24 h) on the short-term storage of Siberian sturgeon (Acipenser baerii) eggs. The results showed that storage medium, temperature, and duration all had significant effects on the fertilization rate, hatching success, and malformation of newly hatched larvae (P < 0.05). With the increase of storage duration, the fertilization and hatching rates decreased, while the malformation rate of hatched larvae increased. The A. baerii eggs stored at 16 degrees C had higher fertilization, hatching, and malformation rates but shorter holding time than those stored at 4 degrees C. The optimal conditions for the short-term storage of A. baerii eggs were Hepes solution prepared according to the biochemical composition of A. baerii coelomic fluid, 16 degrees C, and 4 h, under which, 86.36% fertilization rate, 94.74% hatching rate, and zero malformation would be obtained.