Tracking pollutants in dietary fish oil: From ocean to table.

Dietary fish oil used in aquafeed transfers marine pollutants to farmed fish. However, the entire transfer route of marine pollutants in dietary fish oil from ocean to table fish has not been tracked quantitatively. To track the entire transfer route of marine pollutants from wild fish to farmed fish through dietary fish oil and evaluate the related human health risks, we obtained crude and refined fish oils originating from the same batch of wild ocean anchovy and prepared fish oil-containing purified aquafeeds to feed omnivorous lean Nile tilapia and carnivorous fatty yellow catfish for eight weeks. The potential human health risk of consumption of these fish was evaluated. Marine persistent organic pollutants (POPs) were concentrated in fish oil, but were largely removed by the refining process, particularly dioxins and polychlorinated biphenyls (PCBs). The differences in the POP concentrations between crude and refined fish oils were retained in the fillets of the farmed fish. Fillets fat content and fish growth were positively and negatively correlated to the final POPs deposition in fillets, respectively. The retention rates of marine POPs in the final fillets through fish oil-contained aquafeeds were 1.3%-5.2%, and were correlated with the POPs concentrations in feeds and fillets, feed utilization and carcass ratios. The dietary crude fish oil-contained aquafeeds are a higher hazard ratio to consumers. Prohibiting the use of crude fish oil in aquafeed and improving growth and feed efficiency in farmed fish are promising strategies to reduce health risks originating from marine POPs.

[Experimental Study of the Diffusion Process of Pulsed-GMAW Plasma with Optical Emission Spectrometry].

In case of GMAW-P application, the product quality is strongly dependent on the arc plasma performances. Therefore, in order to improve the application, it is important to understand and characterize the fundamental plasma properties. In this paper, different techniques (high speed camera ，optical emission spectroscopy system, electrical data acquisition system, synchronous triggering device) were used to characterize the arc characteristic. The metal diffusion process from the peak time to the base time is discussed, as well as its physical characteristics. The results show that, in the peak time phase, a high concentration of metal vapor arc is concentrated in the plasma center of the range of about 1 mm, during the transition from the peak to the base pulse periods, the diffusion leads to an iron vapor flux from regions in the arc core to the arc fringes. The iron mol fraction of the peak time was up to 75%, only taking up 35% of the base time.

[Study of the Laser Absorption Characteristics of CO(2), Laser-Pulsed GMAW Hybrid Welding Based on Spectral Diagnosis Technique].

During the process of laser are hybrid welding, the metal vapor from the wire end has great influence on the electron number and the particles in the plasma, which changes the absorption of the laser irradiation and the energy input to workpiece. In this paper, an optical emission spectroscopy system was employed to estimate plasma temperature and the electron number densities distribution. A high speed camera was used to analyze the plasma shape behavior. By using the Beer-Lambert law, the laser absorption rate under different welding mode was calculated. The result show that the metal vapor from the wire tip lead the electron density increase, and it make the laser energy absorption rates decreased.

[Study of the effect of heat source separation distance on plasma physical properties in laser-pulsed GMAW hybrid welding based on spectral diagnosis technique].

In the present paper, the authors calculated the plasma's peak electron temperatures under different heat source separation distance in laser- pulse GMAW hybrid welding based on Boltzmann spectrometry. Plasma's peak electron densities under the corresponding conditions were also calculated by using the Stark width of the plasma spectrum. Combined with high-speed photography, the effect of heat source separation distance on electron temperature and electron density was studied. The results show that with the increase in heat source separation distance, the electron temperatures and electron densities of laser plasma did not changed significantly. However, the electron temperatures of are plasma decreased, and the electron densities of are plasma first increased and then decreased.

[Welding arc temperature field measurements based on Boltzmann spectrometry].

Arc plasma, as non-uniform plasma, has complicated energy and mass transport processes in its internal, so plasma temperature measurement is of great significance. Compared with absolute spectral line intensity method and standard temperature method, Boltzmann plot measuring is more accurate and convenient. Based on the Boltzmann theory, the present paper calculates the temperature distribution of the plasma and analyzes the principle of lines selection by real time scanning the space of the TIG are measurements.

[Calculation and analysis of arc temperature field of pulsed TIG welding based on Fowler-Milne method].

Pulsed TIG welding is widely used in industry due to its superior properties, and the measurement of arc temperature is important to analysis of welding process. The relationship between particle densities of Ar and temperature was calculated based on the theory of spectrum, the relationship between emission coefficient of spectra line at 794.8 nm and temperature was calculated, arc image of spectra line at 794.8 nm was captured by high speed camera, and both the Abel inversion and Fowler-Milne method were used to calculate the temperature distribution of pulsed TIG welding.

[Calculating the stark broadening of welding arc spectra by Fourier transform method].

It's the most effective and accurate method to calculate the electronic density of plasma by using the Stark width of the plasma spectrum. However, it's difficult to separate Stark width from the composite spectrum linear produced by several mechanisms. In the present paper, Fourier transform was used to separate the Lorentz linear from the spectrum observed, thus to get the accurate Stark width. And we calculated the distribution of the TIG welding arc plasma. This method does not need to measure arc temperature accurately, to measure the width of the plasma spectrum broadened by instrument, and has the function to reject the noise data. The results show that, on the axis, the electron density of TIG welding arc decreases with the distance from tungsten increasing, and changes from 1.21 X 10(17) cm(-3) to 1.58 x 10(17) cm(-3); in the radial, the electron density decreases with the distance from axis increasing, and near the tungsten zone the biggest electronic density is off axis.

[The reconstruction of welding arc 3D electron density distribution based on Stark broadening].

The three-dimensional electron density is very important for welding arc quality control. In the present paper, Side-on characteristic line profile was collected by a spectrometer, and the lateral experimental data were approximated by a polynomial fitting. By applying an Abel inversion technique, the authors obtained the radial intensity distribution at each wavelength and thus constructed a profile for the radial positions. The Fourier transform was used to separate the Lorentz linear from the spectrum reconstructed, thus got the accurate Stark width. And we calculated the electronic density three-dimensional distribution of the TIG welding are plasma.

[Genetic structure of wild Macrobrachium nipponense populations in Taihu Lake based on microsatellite analysis].

By using eight highly polymorphic microsatellite DNA loci, this paper analyzed the genetic structure of wild Macrobrachium nipponense populations in Taihu Lake. For the 15 M. nipponense populations in the Lake, there were at least three of the loci presenting heterozygosity deficiency and obvious deviation from Hardy-Weinberg equilibrium after Bonferroni correction. The observed heterozygosity values of the 15 populations were all above 0. 683, displaying a high genetic diversity, but the diversity varied obviously with site. For example, the genetic diversity of the eastern and southern populations at Dukou and Luxiang was higher than that of the western and northern populations at Huazhuang and Yangzhu. For the 15 populations, parts of the loci showed heterozygote excess and departure from mutation-drift equilibrium, suggesting that the population structure had experienced bottleneck effect and the population amount had declined. The AMOVA analysis across all the populations and loci showed that the genetic divergence among the 15 populations was at a lower level (F(ST) = 0.011 ). 98.9% of the genetic variation came from intra-population, and 1.1% came from inter-population, suggesting that all the M. nipponense populations in the Lake could be protected and managed as a single unit in genetic resource. However, the genetic distance between Huazhuang and Wutangmen populations reached 0.206, being close to the delimitation of species identification. Further studies would be needed for the sustainable utilization of the genetic resource of M. nipponense in Taihu Lake.