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In this study, we evaluated the intestinal contents of Pacific whiteleg shrimp (Litopenaeus vannamei), the visceral mass of razor clams (Sinonovacula constricta) and the water columns and the substrate sediments in different culture-density groups in a L. vannamei–S. constricta tandem-culture model by high-throughput sequencing of the 16S rRNA gene. The results show that the culture density affected the bacterial floral structure of the water columns, substrate sediment and razor-clam gut masses without making significant differences in the bacterial flora structure of the shrimp gut; the Shannon diversity indexes of the bacterial communities in the substrate sediment, shrimp gut and razor-clam gut masses were not significantly different among the density groups, and the Shannon diversity index of the bacterial communities in the water column was higher in the group with higher culture densities; at the phylum level, the dominant bacteria common to the shrimp guts, razor-clam visceral mass, water columns and substrate sediment were Proteobacteria and Bacteroidetes; Chloroflexi was the dominant bacterium specific to the substrate sediment; and Firmicutes was the dominant bacterium specific to the shrimp gut and razor-clam gut mass. We used national standards (GB 17378.4-2007, China) to evaluate the content of water-quality factors through the environmental factors and the genus-level correlation analysis of bacterial flora that follow: the dominant bacterium in the water column, uncultured_bacterium_f_Rhodobacteraceae, was negatively correlated with PO43−-P; the dominant bacteria in the substrate sediments, uncultured_bacterium_f_Anaerolineaceae and Woeseia, were significantly and negatively correlated with DO; and the dominant bacteria Lactococcus spp. in the razor-clam gut mass and the shrimp intestines were positively correlated with DO. These results show that culture density directly affects water-quality factors, which in turn affect the culture environment and the composition structure of the bacterial flora in a cultured organism. [ABSTRACT FROM AUTHOR]

Random matrix theory is applied in the financial field to study the correlation of the financial correlation coefficient matrix, which is a key factor in network construction. In this paper, the random matrix theory is combined with network construction to study the art financial risk prediction algorithm based on the random matrix. Based on the stochastic matrix theory and the key nodes of the network, the financial network and the "noise" network before and after the "denoising" are analyzed and compared. It is found that the key and important information of the original network is still retained after the "denoising" of the network, and the noise information corresponds to the information represented by the smaller nodes in the original network. Based on the stochastic matrix of artwork financial risk prediction, the topological properties of the financial network before and after denoising are analyzed and compared from the perspectives of minimum spanning tree, model, and community structure. Based on the random matrix theory, this paper discusses the financial correlation coefficient matrix and the statistical properties of the eigenvalues of the random matrix, and on this basis, the existing denoising methods are improved, the correlation coefficient matrix more suitable for constructing the financial network is established, and the art financial risk prediction algorithm is constructed. Then, based on the stochastic matrix theory and the key nodes of the network, the financial network and the noise network before and after denoising are analyzed and compared. It is found that the key and important information of the original network is still retained after denoising the network, and the noise information corresponds to the information represented by the relatively small nodes in the original network. Finally, based on the stochastic matrix of art financial risk prediction, analysis of the financial network topology, such as minimum spanning tree, model, and community structure, found that the improved financial network topology is more obvious and the structure is closer. [ABSTRACT FROM AUTHOR]

A healthy mental status of students plays an important role in getting quality of education. Hence, research on the prediction of college students' mental health status is of great importance and considered as a hot area of research. In this specific research study, back propagation (BP) algorithm is adopted to learn verities of characteristics of different students from the historical data of the students including: psychological characteristics, basic personal characteristics, and socio-economic characteristics. In the initial stage of the modeling, data preprocessing steps are used to prepare the data to be used by the BP algorithm for building model. The rationales behind the use of BP algorithm are its capability of handling heterogeneity of data and exploring correlations among different characteristics. The proposed model enhances the capability of BP algorithm for risk prediction of psychological problem of the students and achieves higher precision of psychological problem prediction. The results obtained show that the error between the predicted and measured values is 0.88%. [ABSTRACT FROM AUTHOR]

As an unusual economically important aquaculture species, Sinonovacula constricta possesses high levels of long-chain polyunsaturated fatty acids (LC-PUFA). Previously, our group identified fatty acyl desaturases (Fad) with Δ5 and Δ6 activities in S. constricta , which was the first report of Δ6 Fad in a marine mollusc. Here, we further successfully characterize elongases of very long-chain fatty acids (Elovl) in this important bivalve species, including one Elovl2/5, two Elovl4 isoforms (a and b) and a novel Elovl (c) with Elovl4 activity. In addition, we also determined the desaturation activity of S. constricta Δ6 Fad toward 24:5n-3 to give 24:6n-3, a key intermediate in docosahexaenoic acid (DHA) biosynthesis. Therefore, S. constricta is the first marine mollusc reported to possess all Fad and Elovl activities required for LC-PUFA biosynthesis via the 'Sprecher pathway'. This finding greatly increases our understanding of LC-PUFA biosynthesis in marine molluscs. Phylogenetic analysis by interrogating six marine molluscan genomes, and previously functionally characterized Elovl and Fad from marine molluscs, suggested that DHA biosynthetic ability was limited to a few species, due to the general lack of Δ4 or Δ6 Fad in most molluscs. • The S. constricta Elovl involved in LC-PUFA synthesis were investigated. • The desaturation ability of S. constricta Δ6 Fad toward 24:5n-3 was determined. • S. constricta is the first mollusc with capacity to operate the Sprecher pathway. • DHA biosynthetic ability was limited to certain marine molluscs. [ABSTRACT FROM AUTHOR]

• Laser polishing in chamber gas shielding and nozzle gas shielding were compared. • Effect of the volume flow rate of the shielding gas on Ra was explored. • The nozzle gas shielding laser polishing was intensively investigated. • A shielding gas jet model was established and verified experimentally. • The influence mechanism of the shielding gas jet on the molten pool was revealed. Gas shielding is critical for improving the quality of laser polishing. The processing effects of laser polishing under the chamber and nozzle gas shielding were compared and analyzed. The influence of the volume flow rate on the surface roughness of the polished workpiece was analyzed, determining the optimal volume flow rate (Q = 5 L/min). At the optimum volume flow rate, the effects of laser power and scanning speed on surface roughness were explored in further research on nozzle gas shielding laser polishing with wider application prospects. A shielding gas jet model for nozzle gas shielding laser polishing was established and verified. The influence mechanism of the shielding gas jet on the polished surface topography was explored using the established shielding gas jet model and laser polishing model, revealing the formation mechanism of surface ripples on the polished surface: the shielding gas jet acts as a perturbation of the molten pool, causing the Marangoni instability of the molten pool when the Marangoni number exceeds the critical Marangoni number. [ABSTRACT FROM AUTHOR]

The morphology of the molten pool plays a crucial role in determining the surface quality of components during laser polishing of 304 stainless steel. Lens ultrasonic vibration significantly impacts the formation of the molten pool during ultrasonic vibration-assisted laser polishing. In this paper, experimental and numerical simulations were applied to investigate the surface properties of ultrasonic vibration-assisted laser polishing. A comparison was conducted between traditional laser polishing and ultrasonic vibration-assisted laser polishing in terms of the difference in peak temperature of the molten pool. The molten pool morphology obtained from the simulation is compared with the experiment results to verify the accuracy of the established model. Consequently, the model exhibits high precision and versatility, allowing for flexibility applied to laser polishing of other systems or materials. The dynamic changes of the temperature field, force field, and velocity field in the molten pool were discussed in detail to reveal the mechanism by which ultrasonic vibration influences. This research work contributes to understanding and guiding the surface formation during ultrasonic vibration-assisted laser polishing of 304 stainless steel. [ABSTRACT FROM AUTHOR]

Attribute reduction is a crucial research area within concept lattices. However, the existing works are mostly limited to either increment or decrement algorithms, rather than considering both. Therefore, dealing with large-scale streaming attributes in both cases may be inefficient. Convolution calculation in deep learning involves a dynamic data processing method in the form of sliding windows. Inspired by this, we adopt slide-in and slide-out windows in convolution calculation to update attribute reduction. Specifically, we study the attribute changing mechanism in the sliding window mode of convolution and investigate five attribute variation cases. These cases consider the respective intersection of slide-in and slide-out attributes, i.e., equal to, disjoint with, partially joint with, containing, and contained by. Then, we propose an updated solution of the reduction set for simultaneous sliding in and out of attributes. Meanwhile, we propose the CLARA-DC algorithm, which aims to solve the problem of inefficient attribute reduction for large-scale streaming data. Finally, through the experimental comparison on four UCI datasets, CLARA-DC achieves higher efficiency and scalability in dealing with large-scale datasets. It can adapt to varying types and sizes of datasets, boosting efficiency by an average of 25%. [ABSTRACT FROM AUTHOR]

Isochrysis galbana is a species of marine microalgae that is principally used to feed the larvae and early juveniles of bivalve mollusks (e.g., ark shells, clams, mussels, oysters and scallops). The artificial hatchery stages of most of these larvae are primarily occur during high-temperature seasons, when the water temperature in the breeding pool frequently exceeds 30 °C and even reaches 35 °C, which may change the lipid composition of I. galbana, thus affecting its nutritional value. In this experiment, we investigated changes in the lipid composition of I. galbana Parke at high temperature using ultra-performance liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry. The results showed that the sulfoquinovosyldiacylglycerol (SQDG), monogalactosyldiacylglycerol (MGDG), diacylglycerylcarboxyhydroxymethylcholine (DGCC) and digalactosyldiacylglycerol (DGDG) contents increased during growth at 20 and 35 °C. Conversely, the lyso-SQDG, lyso-MGDG, lyso-DGDG, lyso-DGCC and triacylglycerol (TAG) contents clearly decreased. Moreover, higher SQDG, MGDG, DGDG and DGCC contents and lower lyso-lipid and TAG contents were observed in I. galbana Parke grown at 35 versus 20 °C. In addition, the content of docosahexaenoic acid (DHA) improved at 20 and 35 °C during growth, and DHA accumulated to greater levels at 35 °C than at 20 °C at the same time points. These results revealed an increase in DHA content as the temperature rose, which indicated that the nutritional value of I. galbana Parke during logarithmic phase improved in the same cultured time with an increasing temperature. [ABSTRACT FROM AUTHOR]

A new method of surface structuring by laser remelting with the help of surface tension (mainly thermocapillary force and solutocapillary force) and volume expansion was proposed. A multiphysics coupled numerical model was proposed for this surface structuring method, in which the calculation of surface tension and solutocapillary force is improved. Using the established numerical model, the formation mechanism of the surface structure was explored from the aspects of surface tension, fluid flow, volume expansion, and surface profile evolution. The reason why the surface structure changes from a "W" shape to an "A" shape was explained, and the contributions of thermocapillary force, solutocapillary force, and volume expansion to the surface structure were investigated. The effects of laser power, scanning speed, and beam diameter on the surface profile of the surface structure were studied by experiments, which indicates that the desired surface structure can be obtained by adjusting the process parameters. All the experimental results were simulated by the established numerical model, and the simulation results are in good agreement with the experimental results, indicating that the numerical model is effective and available. • A new surface structuring by laser remelting was proposed. • The function between main chemical elements and the surface tension was established. • A multiphysics coupled model for the surface structuring was established and verified. • The contributions of thermocapillary force, solutocapillary, and volume expansion was investigated. • The formation mechanism of the surface structure was revealed. [ABSTRACT FROM AUTHOR]

For the machining process of industrial parallel robots, the gravity generated by the weight of mobile platform and links will lead to the deviation of the expected machining trajectory of the tool head. In order to evaluate this deviation and then circumvent it, it is necessary to perform the robotic stiffness model. However, the influence of gravity is seldom considered in the previous stiffness analysis. This paper presents an effective stiffness modeling method for industrial parallel robots considering the link/joint compliance, the mobile platform/link gravity, and the mass center position of each link. First, the external gravity corresponding to each component is determined by the static model under the influence of gravity and mass center position. Then, the corresponding Jacobian matrix of each component is obtained by the kinematic model. Subsequently, the compliance of each component is obtained by cantilever beam theory and FEA-based virtual experiments. In turn, the stiffness model of the whole parallel robot is determined and the Cartesian stiffness matrix of the parallel robot is calculated at several positions. Moreover, the principal stiffness distribution of the tool head in each direction over the main workspace is predicted. Finally, the validity of the stiffness model with gravity is experimentally proved by the comparison of the calculated stiffness and measured stiffness in identical conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new type of surface structure is observed in the laser polishing experiments. • A multi-physics coupling model for the surface structure is established. • The formation mechanism of the surface structure is revealed. • The contribution of five factors (capillary force, thermocapillary force, recoil pressure, material removal, and volume expansion) to the surface structure was investigated. • The effectiveness of the numerical model is verified. Laser polishing is an innovative surface finishing technology to reduce surface roughness through the interaction of laser and material. However, some new surface structures will be introduced into the polished surface, reducing the surface quality of the polished workpiece. This paper investigated the formation mechanism of a new type of surface structure that has not been studied before. The laser polishing experiments presented the complete evolution of the surface profile and size parameters of the surface structure with the laser power, and the reason for the formation of the surface structure was preliminary analyzed. Furthermore, a two-dimensional numerical model coupled with heat transfer, fluid flow, material vaporization, and volume expansion was established to further explore the formation mechanism of this type of surface structure. With the help of the established numerical model, the temperature field, flow field, material vaporization, and volume expansion were analyzed during the formation process of surface structure. The contribution of five factors (capillary force, thermocapillary force affected by surface-active elements, recoil pressure, material removal, and volume expansion) to the formation of the surface structure was investigated, illustrating that this type of surface structure is the result of the combined effects of these factors. In addition, the surface profile and size parameters of the surface structure were simulated, which were in good agreement with the experimental results. This work further improves the theory of laser polishing, which is of great significance to promote the application of laser polishing. Importantly, this paper demonstrates the potential of laser surface structuring under the combined action of the surface tension, recoil pressure, material removal, and volume expansion of the molten pool in laser processing. [ABSTRACT FROM AUTHOR]

The two morphologically similar microalgae NMBluh014 and NMBluh-X belong to two different strains of Nannochloropsis oceanica. They possess obviously different feeding effects on bivalves, but are indistinguishable by 18S rRNA and morphological features. In this work, lipidomic analysis followed by principal component analysis and orthogonal projections to latent structures discriminant analysis provided a clear distinction between these strains. Metabolites that definitively contribute to the classification were selected as potential biomarkers. The most important difference in polar lipids were sulfoquinovosyldiacylglycerol (containing 18:1/16:0 and 18:3/16:0) and monogalactosyldiacylglycerol (containing 18:3/16:3 and 20:5/14:0), which were detected only in NMBluh-X. Additionally, an exhaustive qualitative and quantitative profiling of the neutral lipid triacylglycerol ( TAG) in the two strains was carried out. The predominant species of TAG containing 16:1/16:1/16:1 acyl groups was detected only in NMBluh-X with a content of ~93.67 ± 11.85 nmol · mg−1 dry algae at the onset of stationary phase. Meanwhile, TAG containing 16:0/16:0/16:0 was the main TAG in NMBluh014 with a content of 40.25 ± 3.92 nmol · mg−1. These results provided the most straightforward evidence for differentiating the two species. The metabolomic profiling indicated that NMBluh-X underwent significant chemical and physiological changes during the growth process, whereas NMBluh014 did not show such noticeable time-dependent metabolite change. This study is the first using Ultra Performance Liquid Chromatography coupled with Electrospray ionization-Quadrupole-Time of Flight Mass Spectrometry (UPLC-Q-TOF-MS) for lipidomic profiling with multivariate statistical analysis to explore lipidomic differences of plesiomorphous microalgae. Our results demonstrate that lipidomic profiling is a valid chemotaxonomic tool in the study of microalgal systematics. [ABSTRACT FROM AUTHOR]

Light irradiation plays an important role in the growth of microalgae and their nutrient composition. To elucidate the effect of different LED lights (red, orange, green, blue, purple, simulated sunlight, and white) on the main nutritional compositions of Isochrysis zhanjiangensis, the growth, fatty acid composition, soluble carbohydrate, and soluble protein contents were studied. The results show that I. zhanjiangensis grew the fastest under blue light (p = 0.044). In terms of fatty acid composition, the percentage of myristic acid (C14:0) decreased significantly (p = 0.021) under blue light and simulated sunlight, but the percentages of palmitic acid (C16:0) (p = 0.032) and stearic acid (C18:0) (p = 0.037) significantly increased. The percentage of docosahexaenoic acid (C22:6n-3) increased under orange light (p = 0.021), and the percentage of total unsaturated fatty acids increased under blue light (p = 0.008). The protein content significantly increased under simulated sunlight (p = 0.025), while the carbohydrate content did not vary much (p > 0.05) under different lights. These findings provide useful guidance for optimizing the cultivation conditions of I. zhanjiangensis to improve its nutritional value and yield. [ABSTRACT FROM AUTHOR]

Diatoms are considered to have great potential as new biofuel sources because they can effectively accumulate triacylglycerols (TAGs). Detailed structure information of TAG in diatoms is much needed not only for the assessment of biofuel quality such as fatty acid chain length and unsaturation degree but also for the tracing of biosynthetic precursors because the biosynthesis of TAG is typically completed by utilizing the diacylglycerol acyltransferase in the cytoplasm. In this report, a comprehensive characterization of TAGs in marine diatoms was performed using ultra performance liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry. Many types of major TAGs were identified for the first time in these diatoms: 12 TAGs in Chaetoceros debilis, 9 TAGs in Phaeodactylum tricornutum Bohlin, 16 TAGs in Nitzschia closterium f. minutissima, 16 TAGs in Thalassiosira weissflogii, 13 TAGs in Thalassiosira sp., 16 TAGs in Stephanodiscus asteaea and 7 TAGs in Skeletonema costatum. Semi-quantification of TAGs in these diatoms was also carried out, and it was found that the contents of individual TAGs ranged from 0.5 ± 0.1 to 217.9 ± 8.1 nmol mg total lipids. In addition, the total lipid contents in diatoms ranged from 143.6 ± 16.3 to 201.1 ± 16.3 mg g dry microalgae and the total TAG contents ranged from 36.8 ± 9.5 to 793.2 ± 54.4 nmol mg total lipids. By comparative analysis of the compositions and concentrations of major TAGs in the seven algal strains, N. closterium f . minutissima with high abundance of TAGs containing the most monounsaturated fatty acids (mainly palmitoleic acid) was considered as one of the most promising diatom strains for microalgal biofuel production. Additionally, based on the information of sn-2 fatty acid obtained (mainly C16 in the sn-2 position), we propose the hypothesis that TAGs in diatoms are mainly derived from lipids in chloroplasts through the prokaryotic biosynthesis pathway, including monogalactosyldiacylglycerol and digalactosyldiacylglycerol. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, we investigated the major lipid changes of six important diet microalgae (Chlorella sp., Nannochloropsis oculata, Nannochloropsis sp., Isochrysis galbana, Phaeodactylum tricornutum Bohlin and Chaetoceros calcitrans) during the entire growth phase using UPLC-Q-TOF MS system. Our results suggested that EPA/AA-rich lipids were largely detected in both Nannochloropsis sp. and N. oculata as a component of diacylglyceryl-N,N,N-trimethylhomoserine (DGTS). Moreover, docosahexaenoic acids (DHAs) were detected only in I. galbana mainly as a component of monogalactosyldiacylglycerol (MGDG) and sulphoquinovosyldiacylglycerol (SQDG). Besides, the growth phase of microalgae could be a useful variable for the content enrichment of EFA-rich lipids. A higher content EPA/AA-rich DGTS could be obtained at the end of stationary phase for Nannochloropsis sp. and N. oculata, and a higher content of DHA-rich lipids could be obtained at the end of stationary phase for I. galbana. However, EPA/AA-rich lipids were mainly detected in both P. tricornutum and C. calcitrans mainly as a component of TAG and MGDG, respectively. In addition, a higher content of EPA-rich TAG could be obtained at the end of the stationary phase for P. tricornutum. A higher content of EPA-rich MGDG could be obtained at the end of stationary phase for C. calcitrans. Taken together, considering the high EFA requirement for artificial rearing of marine organisms, Nannochloropsis sp., N. oculata, P. tricornutum, C. calcitrans and I. galbana would be highly recommended to be harvested at the end of the stationary phase. The distribution characteristics of EFA-rich lipids related to 6 microalgae are described in detail. [Copyright &y& Elsevier]

RATIONALE The precise identification of fatty acids at the sn-2 position of triacylglycerols (TAGs), especially for positional regioisomers (AAB/ABA), needs to be established during mass spectrometry analysis. The detailed structural information about TAGs is significant not only for the assessment of biofuel quality, but also for the tracing of biosynthetic precursors. METHODS Total lipid was extracted from T. pseudonana by a modified Bligh and Dyer method. The qualitative analysis of TAGs in T. pseudonana was carried out using ultra-performance liquid chromatography/electrospray ionization-quadrupole time-of-flight mass spectrometry (UPLC/ESI-Q-TOF-MS). The raw LC/MS data were analyzed using MassLynx software (version 4.1, Waters). RESULTS The acyl group at the sn-2 position of the TAGs has been identified unequivocally by [M + Li-R1/3COOH-R2CH = CHCOOH]+ and the abundance of [M + Li-R1/3COOH-R2CH = CHCOOH]+ can be used to confirm whether the TAG isomers are co-eluted. In total, twelve TAGs were identified in T. pseudonana based on the fragmentation patterns discussed above. The data indicated that only C16 fatty acids were located at the sn-2 position, which was important to trace the biosynthetic precursors of TAGs. CONCLUSIONS We put forward a hypothesis that TAGs in T. pseudonana are only derived from lipids in chloroplasts through prokaryotic biosynthesis pathway based on the precise information of sn-2 fatty acids, which is significant not only for the assessment of biofuel quality, but also for the tracing of biosynthetic precursors. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

RATIONALE Glycosphingolipids (GSLs) are important components of the cell membrane; however, little is known about GSLs in microalgae. We analyzed GSLs in three strains of Skeletonema microalgae by liquid chromatography coupled with mass spectrometry. METHODS Total lipid was extracted from Skeletonema microalgae. Separation of lipids was achieved via reversed-phase liquid chromatography, and mass spectrometric analysis of the lithium adduct of GSLs was conducted to determine their structures. RESULTS Two types of novel glycosphingolipids were identified from three strains of Skeletonema microalgae. The N-acyl groups were primarily long-chain saturated or monoenoic fatty acids (monounsaturated fatty acids) with 16C and 20 to 24C. The sphingoid long-chain bases (LCB) were sphingosine, sphingadienine and sphingatrienine. The saccharide polar head groups of glycosphingolipids were disaccharide (heptose-hexose) or trisaccharide (heptose-hexose-hexose). Semi-quantitative analysis of GLSs in the three strains of microalgae showed that GSL contents ranged from 0.09 to 8.79 nmol/mg dry microalgae powder. CONCLUSIONS A qualitative method was developed for the identification of GSLs in microalgae. Two types of novel GSLs were identified from three strains of Skeletonema, which might have important biological functions. It could also provide a reliable tool for chemotaxonomy of microalgae. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Ultra Performance Liquid Chromatography-Electrospray ionization-Quadrupole-Time of Flight Mass Spectrometry (UPLC-ESI-Q-TOF-MS) is a powerful lipidomic tool. In this study, we developed a UPLC/Q-TOF-MS based method to investigate the lipid metabolomic changes in different growth phases of Nitzschia closterium f. minutissima. The data classification and biomarker selection were carried out by using multivariate statistical analysis, including principal components analysis (PCA), projection to latent structures with discriminant analysis (PLS-DA), and orthogonal projection to latent structures with discriminant analysis (OPLS-DA). We discovered that the intercellular lipid metabolites were significantly different among exponential, early stationary and late stationary phases. Thirty-one lipid molecules were selected and identified as putative biomarkers, including free fatty acid, Harderoporphyrin, phosphatidylglycerol, 1,2-diacyglycerl-3-O-4′-(N,N-trimethy)-homoserine, triacylglycerol, cholesterol, sulfoquinovosyldiacylglycerol, lyso-sulfoquinovosyldiacylglycerol, monogalactosyldiacylglycerol, digalactosyldiacylglycerol and lyso-digalactosyldiacylglycerol. These lipids have been shown previously to function in energy storage, membrane stability and photosynthesis efficiency during the growth of diatoms. Further analysis on the putative biomarkers demonstrated that nitrate starvation played critical role in the transition from exponential phase to stationary phase in N. closterium. This study is the first one to explore the lipidomic changes of microalgae in different growth phases, which promotes better understanding of their physiology and ecology. [ABSTRACT FROM AUTHOR]

The serum polar lipid metabolic changes for two common cage-cultured fishes, yellow coraker Pseudosciaena crocea and Japanese seabass Lateolabrax japonicus, after tropical storm attack have been studied by ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-qTOF-MS). The full scan mass spectrometry combined with principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) indicated that yellow croaker underwent significant chemico-physiological changes during the recovery process, whereas Japanese seabass did not show such noticeable time-dependent consistent metabolites change patterns. Further identification of the metabolite biomarkers showed the increase of phosphatidylcholine with high unsaturated fatty acid and lysophospholipids, and the decrease of phosphatidylcholine with saturated fatty acids and plasmologens, which indicated the need of energy supplement and successive stressful inflammation. The increase of taurocholic acid and decrease of cortol could be regarded as the physiological alleviation measure during the recovery period. This is the first metabolomic study to tackle the fish physiological response for the complex environmental changes, and demonstrated that lipidomics is an effective analytical tool for predicting the stress resistance of fish to ultra uncontrolled environmental stress. [ABSTRACT FROM AUTHOR]

Abstract: Puffer fish (Takifugu obscurus) from the Yangtze River of China were screened for tetrodotoxin-producing bacteria. An Aeromonas strain was isolated from the ovary of the puffer fish and was shown to produce tetrodotoxin; this strain was denoted Ne-1. The identity of tetrodotoxin produced by strain Ne-1 was confirmed by mouse bioassay, high performance liquid chromatography coupled with mass chromatography (LC-MS), and ELISA. Strain Ne-1 was characterized morphologically, biochemically, and by 16S rDNA phylogenetic analysis; these analyses suggested that strain Ne-1 is closely related to Aeromonas molluscorum. Given that strain Ne-1 was isolated from the ovary of T. obscurus, we propose that the TTX-producing Aeromonas sp. is a parasite or symbiotic bacterium rather than a sample contaminant. Collectively, our studies suggest that Aeromonas sp. strain Ne-1 produces tetrodotoxin in T. obscurus. [Copyright &y& Elsevier]

Abstract: The biomedical NiTi alloy was treated by micro-arc oxidation in an electrolytes containing sodium aluminate and sodium hypophosphite at 400V constant voltages for 30min. The MAO-treated NiTi has a porous microstructure on its surface and coatings consisting only of the γ-Al2O3 phase. The ceramic coating prepared by micro-arc oxidation is composed of Al, Ti, Ni, O, and P with the atomic concentration of 26.98%, 3.67%, 3.33%, 65.30% and 0.72%, respectively. The MAO-treated NiTi was soaked in a simulated body fluid (1.0SBF) to investigate the biomimetic deposition of apatite on the surface of Al2O3 coated NiTi alloy. It was found that Al2O3 coated NiTi alloy shows an excellent apatite-forming ability after soaking in a simulated body fluid (1.0SBF) for 14days, while no apatite-forming ability was observed on bared NiTi alloy even though soaking time is up to 28days. [Copyright &y& Elsevier]

Abstract: The photosynthetic glycerolipids composition of algae is crucial for structural and physiological aspects. In this work, a comprehensive characterization of the photosynthetic glycerolipids of the diatom Stephanodiscus sp. was carried out by ultra performance liquid chromatography–electrospray ionization-quadrupole-time of flight mass spectrometry (UPLC–ESI-Q-TOF MS). By use of the MSE data collection mode, the Q-TOF instrument offered a very viable alternative to triple quadrupoles for precursor ion scanning of photosynthetic glycerolipids and had the advantage of high efficiency, selectivity, sensitivity and mass accuracy. Characteristic fragment ions were utilized to identify the structures and acyl compositions of photosynthetic glycerolipids. Comparing the abundance of fragment ions, it was possible to determine the position of the sn-glycerol-bound fatty acyl chains. As a result, four classes of photosynthetic glycerolipid in the extract of Stephanodiscus sp. were unambiguously identified, including 16 monogalactosyldiacylglycerols (MGDGs), 9 digalactosyldiacylglycerols (DGDGs), 23 sulfoquinovosyldiacylglycerols (SQDGs) and 8 phosphatidylglycerols (PGs). As far as our knowledge, this is the first report on global identification of photosynthetic glycerolipids, including lipid classes, fatty acyl composition within lipids and the location of fatty acids in lipids (sn-1 vs. sn-2), in the extract of marine microalgae by UPLC–ESI-Q-TOF MS directly. [Copyright &y& Elsevier]

• Simulation and modeling on laser polishing in melting and transition regimes. • Mechanism of surface topography evolution in laser polishing is revealed. • Contributions of surface forces and material removal in laser polishing are analyzed. • Thermocapillary force affected by surface-active component results in a bulge structure on the polished surface. • Surface roughness prediction is tried through the established model with a maximum error of 14.9%. Previous studies on the mechanism of laser polishing were limited to the melting regime, this paper proposed a numerical model for the melting and transition regimes of laser polishing, which coupled heat transfer, fluid flow, and material vaporization. Based on the model, the evolution of the temperature and velocity fields of the molten pool in laser polishing was presented. And the mechanism of surface topography evolution was revealed from the perspective of surface forces (capillary force, thermocapillary force, and recoil pressure), fluid velocity, and material removal. Furthermore, the corresponding relationships between surface forces, fluid velocity, and surface topography were determined. The contributions of surface forces and vaporization front velocity in laser polishing were investigated, and the reason for the formation of the bulge structure and the influence of laser power on it were analyzed. And the velocity direction change points which have a great influence on the surface evolution were found, and the method to determine the positions of these points was proposed. Besides, the surface roughness prediction after laser polishing was tried through the numerical model, and the maximum error between the predicted results and the experimental results is 14.9%. Therefore, this model can be used to optimize process parameters. [ABSTRACT FROM AUTHOR]

As a burgeoning surface finishing process, laser polishing (LP) introduces some undesired surface structures, limiting access to better laser-polished surfaces. Considering this, the paper proposes a novel hybrid processing method, ultrasonic vibration-assisted laser polishing (UVLP). Horizontal ultrasonic vibration, perpendicular to the laser scanning direction, is imposed on the workpiece, which promotes homogenized melt distribution in the melting pool, contributing to the polished surface flatness. Bulge, a typical surface structure formed in LP, serves as the verification vehicle for the effect of ultrasonic vibration here. In this investigation, comparative experiments were performed on 304 stainless steels to demonstrate the regulation phenomenon of ultrasonic vibration on the bulge formation. Subsequently, the corresponding numerical model was developed to explore the acting mechanisms of ultrasound from the thermal and hydrodynamic fields. The model also optimized the coupling method of volume expansion to better capture the change in melting pool volume during the polishing process, especially during the cooling phase. The results indicated that the forced melt oscillations are the dominant mechanism to uniformize the metallic materials distribution, regulating the bulge formed along the polished track. The degraded melt flow pattern, a simple harmonic oscillation, reached similar results. Furthermore, the developed model verified its effectiveness through surface flatness, melting pool dimensions, and microhardness. • A new hybrid processing method, ultrasonic vibration-assisted laser polishing (UVLP), is proposed. • The regulation phenomenon of ultrasonic vibration on the bulge formation is visualized. • The acting mechanisms of ultrasonic vibrations in UVLP are analyzed theoretically and experimentally. • A UVLP model is developed and its effectiveness is verified. • The coupling method for volume expansion is optimized. [ABSTRACT FROM AUTHOR]

Understanding the metabolic effects of fatty acids on fish intestine is critical to the substitution of fish oil with vegetable oils in aquaculture. In this study, the effects of eicosapentaenoic acid (EPA) and palmitic acid (PA) on fish intestine were evaluated in vitro and in vivo. As the first step for in vitro study, an intestinal cell line (SPIF) was established from silver pomfret (Pampus argenteus). Thereafter, the effects of EPA and PA on cell viability, prostaglandin E2 (PGE2) production, and the expression of genes related to heat shock response, inflammation, extracellular matrix (ECM) formation and degradation were examined in SPIF cells. Finally, these metabolic effects of EPA and PA on the intestine were examined in zebrafish (Danio rerio) larvae. Results showed that all tested fatty acids (PA, oleic acid, linoleic acid, α-linolenic acid, arachidonic acid, and docosahexaenoic acid) except EPA reduced SPIF viability to distinct degrees at the same concentrations. PA decreased SPIF viability accompanied by an increase in PGE2 level. Meanwhile, PA increased the expression of genes related to heat shock response (grp78 , grp94 , hsp70 , and hsp90) and inflammation (nf-κb , il-1β , and cox2). Furthermore, PA reduced the expression of collagen type I (col1a1a and col1a1b) and extracellular matrix (ECM) degradation-related gene mmp2 , while up-regulating timp2 mRNA expression. In vivo , PA also increased hsp70 , il-1β , and cox2 mRNA levels and limited the expression of collagen type I in the larval zebrafish intestine. Interestingly, the combination of EPA and PA partially recovered the PA-induced changes in cell viability, PGE2 production, and mRNA expression in vitro and in vivo. These results suggest that PA may result in heat shock and inflammatory responses, as well as alter ECM formation and degradation in fish intestine, while EPA could at least partially mitigate these negative effects caused by PA. • An intestinal cell line from silver pomfret (SPIF) was developed as a study model. • Except for EPA, PA, OA, LA, ALA, ARA and DHA decreased SPIF viability to distinct degrees. • PA induced heat shock and inflammatory responses, and affected repair processes in fish intestine. • EPA mitigated PA-induced negative effects on fish intestine. [ABSTRACT FROM AUTHOR]

Summary: Fucoxanthin, a natural carotenoid that has substantial pharmaceutical value due to its anticancer, antioxidant, antiobesity, and antidiabetic properties, is biosynthesized from glyceraldehyde‐3‐phosphate (G3P) via a series of enzymatic reactions. However, our understanding of the transcriptional mechanisms involved in fucoxanthin biosynthesis remains limited.Using reverse genetics, the med8 mutant was identified based on its phenotype of reduced fucoxanthin content, and the biological functions of MED8 in fucoxanthin synthesis were characterized using approaches such as gene expression, protein subcellular localization, protein–protein interaction and chromatin immunoprecipitation assay.Gene‐editing mutants of MED8 exhibited decreased fucoxanthin content as well as reduced expression levels of six key genes involved in fucoxanthin synthesis, namely DXS, PSY1, ZDS‐like, CRTISO5, ZEP1, and ZEP3, when compared to the wild‐type (WT) strain. Furthermore, we showed that MED8 interacts with HSF3, and genetic analysis revealed their shared involvement in the genetic pathway governing fucoxanthin synthesis. Additionally, HSF3 was required for MED8 association with the promoters of the six fucoxanthin synthesis genes.In conclusion, MED8 and HSF3 are involved in fucoxanthin synthesis by modulating the expression of the fucoxanthin synthesis genes. Our results increase the understanding of the molecular regulation mechanisms underlying fucoxanthin synthesis in the diatom P. tricornutum. [ABSTRACT FROM AUTHOR]

The primary cause of tool failure in rough cutting is the severe tool-chip friction brought on by chip adhesion and abrasive wear. To address the problem, the influence of combinations of micro-textures and AlCrN coating, and the sequence of their combinations on tool surface characteristics and cutting performance in dry cutting AISI 304 were investigated. The results of wettability and indentation tests indicate the micro-textures reduce the contact angle of the tool surface (by 13.26%) and increase the contact area between micro-textures and the coating, resulting in a better adhesive strength (grade HF3) for the first micro-textured and then AlCrN-coated tool (TCT). The results of cutting experiments demonstrate that the TCT's cutting performance is improved as the cutting speed increases between 50 and 141 m/min, with the highest reductions in main cutting force and radial cutting force reaching 27% and 38% at 141 m/min. The TCT's micro-textures reduce tool-chip contact area, while the intact AlCrN coating film decreases chip adhesion and improves the wear resistance of cutting tools. This study is expected to be applied to further improve the tool performance under dry and rough cutting conditions. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration-assisted powder feeding (UVPF) technology enables precise point-by-point delivery of powder in additive manufacturing. However, it is prone to compaction and blockage by prolonged vibration. In this paper, an UVPF system combining spiral conveying and ultrasonic vibration was designed and evaluated. The study presents an improved three-dimensional numerical model based on the discrete element method and investigates the evolution of the particle velocity field. The findings demonstrated that there are differences in the dynamic behavior of particles in different locations. The mechanisms of vibration frequency and impact stress are described in terms of powder flow pattern and friction resistance. However, the vibration parameters have no impact on the powder's falling initial velocity. Cohesion between the particles is the key parameter to determine the compaction. During ultrasonic vibration, the cohesion between particles located further away from the tube wall increases, leading to a compaction effect. [Display omitted] • Ultrasonic friction reduction changes the powder flow from funnel to mass flow. • The impact stress on the tube wall during vibration is analyzed. • The vibration parameters have no impact on the velocity of the powder falling. • Powder located further away from the tube wall is more easily compacted. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms of lipid transport and metabolism in fish is crucial to enhance dietary lipid utilization. Here, fatty acid translocase (CD36) gene was characterized in silver pomfret (Pampus argenteus). The open reading frame of silver pomfret cd36 gene was 1395 bp, encoding 464 amino acids. The silver pomfret CD36 protein contained typical transmembrane regions and N-glycosylation modification sites, and was localized to the cytomembrane. The cd36 gene was ubiquitously expressed in all tested tissues, with the highest expression observed in brain tissue. In vivo , both fasting and short-term high-fat feeding could increase cd36 expression in intestinal tissue. In vitro , cd36 expression was induced by palmitic acid, oleic acid, linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid treatment in intestinal tissue. Furthermore, dual-luciferase reporter assay results indicated that peroxisome proliferator-activated receptor gamma (PPARγ) could enhance cd36 promoter activity, and the co-expression of cd36 and pparγ was observed in EPA-incubated intestine, suggesting that EPA may regulate the expression of cd36 via PPARγ to maintain the homeostasis of intestinal lipid metabolism in silver pomfret. These results highlighted the crucial role of CD36 in silver pomfret, and suggested that the cd36 expression may be regulated by PPARγ. This study could contribute to a greater understanding of lipid metabolism and the development of effective strategies for nutrient requirements in fish. [Display omitted] • CD36 was identified and characterized in silver pomfret. • Silver pomfret CD36 possessed typical transmembrane receptor characteristics. • Silver pomfret cd36 expression was regulated by nutritional status and LCFAs. • EPA might regulate Silver pomfret cd36 expression via PPARγ pathway. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) was conducted on H13 steel prior to plasma nitriding (PN). The optical microscopy (OP), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), microhardness tester and ball-on-disk wear tester were employed to investigate the microstructure and properties of plasma nitrided H13 steel coupled with LSP processing. The results show that a large number of dislocations, as well as dislocation cells and nanocrystals composed of high-density dislocations, are observed in H13 steel after LSP treatment. Compared with the PN sample, the diffraction peak intensities of the Fe 3 N phase in the LSP + PN sample are slightly enhanced and the diffraction peaks shift to the right as a whole. Compared to the PN sample, the LSP + PN sample exhibits significant improvements in various aspects. Specifically, the white bright layer and diffusion layer of the LSP + PN sample increased by approximately 25 % and 119.4 %, respectively. Additionally, the thickness of the effective hardened layer increased by around 50 %, and the microhardness increased by approximately 31.3 %. The LSP + PN sample has the better wear resistance than that of the PN sample, with the friction coefficient, wear scar width, wear volume, and wear rate reduced by 11.1 %, 8.4 %, 7.9 %, and 7.3 %, respectively. Through parallel experiments, the experimental error is controlled within 2 %. • The intensity of the Fe 3 N phase in the LSP+PN sample are slightly enhanced and shifted to the right. • LSP can significantly improve the efficiency of plasma nitriding, and obtain thicker nitriding layers. • The LSP+PN sample has the better microhardness and wear resistance than that of the PN sample. • A large number of dislocation cells and nanocrystals composed of high-density dislocations are observed. [ABSTRACT FROM AUTHOR]

The large-scale farming of Nannochloropsis spp. has long been subject to high temperature. Though salicylic acid is widely used to enhance the high temperature resistance of higher plants, related research in microalgae is still in its infancy. In this study, Nannochloropsis oceanica cells at 25 °C were transferred to high temperature (35 °C) for 96 h, during which period salicylic acid with various concentrations (0, 15, 25, 35, and 50 mg L−1) were added into high temperature groups. The results indicated that high temperature could heavily inhibit the growth of N. oceanica, and result in various physiological and biochemical changes. The addition of exogenous salicylic acid at moderate concentration distinctly alleviated the inhibition of heat stress on N. oceanica. Moreover, further analysis indicated that exogenous salicylic acid could significantly increase the contents of soluble sugars, soluble proteins, total unsaturated fatty acids, and catalase activity, but result in the decrease of the nitrate reductase activity, the malondialdehyde content, and fatty acid profile. Our results also demonstrated that salicylic acid at a concentration of 15 mg L−1 received the best growth performance of N. oceanica under 35 °C. This study investigates the thermal protection effect of salicylic acid on N. oceanica under high temperature, and can provide valuable information for the large-scale production of microalgae. [ABSTRACT FROM AUTHOR]

The razor clam Sinonovacula constricta is the first marine mollusk demonstrated to possess the complete long-chain polyunsaturated fatty acids (LC-PUFA) biosynthetic pathway. This study explored the impact of different microalgae on growth, Fad and Elovl expressions, and fatty acid (FA) profiles in juvenile S. constricta. Results revealed that juveniles fed with Isochrysis galbana (rich in DHA) or Chaetoceros calcitrans (rich in EPA) consistently exhibited higher growth than those fed Chlorella sp. (rich in LA and ALA), underscoring the importance of dietary LC-PUFA in S. constricta's development. Expression of most Fad and Elovl in C. calcitrans and I. galbana-fed juveniles were initially up-regulated, then down-regulated, suggesting LC-PUFA demand for faster growth. Although Chlorella sp.-fed juveniles exhibited decreased mRNA levels for most genes, levels were notably higher lately compared to those fed C. calcitrans or I. galbana, hinting at potential LC-PUFA biosynthesis induction. FA profiles in S. constricta generally mirrored those in ingested microalgae, implying direct FA accumulation from diets. Some microalgal FA were absent in farmed S. constricta, while others emerged, indicating S. constricta's ability to selectively accumulate and synthesize FA. This study enhances the understanding of dietary FA metabolism in S. constricta, valuable for selecting appropriate microalgae in its farming practices. [ABSTRACT FROM AUTHOR]

Abstract The modified layers were prepared on the Ti-6Al-4V surface using plasma-pulsed detonation (PPD) treatment. The effects of number of pulses on the microstructure, phase composition, microhardness and wear resistance of the modified layers were studied, and the strengthening mechanism of the modified layers was discussed. The results show that the modified layers are composed of TiN, Ti x O y and Ti phases. The grains of the modified layers are refined to nanoscale (≤100 nm) or near-nanometer (100–300 nm). The increase of the Ti-6Al-4V surface microhardness is mainly attributed to the second phase strengthening and the fine grain strengthening. The average microhardness of the modified layers increases with increasing the number of pulses, and the maximum microhardness value of the all modified layers is at 10 μm near the surface. In addition, the maximum microhardness value of the all modified layers can be up to 561 ± 9 HK 0.01 , which is about 69% higher than that of the substrate. After PPD treatment, the wear mechanism changes from typical abrasive wear and adhesive wear to three-body abrasive wear. Compared with the substrate, the wear volume decreases by about 70%, 79% and 87%, when number of pulses are 1, 2 and 3, respectively, indicating that the wear resistance of Ti-6Al-4V can be greatly improved after PPD treatment. Highlights • Plasma-pulsed detonation is used to improve wear resistance of Ti-6Al-4V. • The modified layers are composed of TiN, TixOy and Ti phases. • The second phase strengthening and the fine grain strengthening are the main mechanism. • The wear mechanism changes from abrasive wear and adhesive wear to three-body abrasive wear. [ABSTRACT FROM AUTHOR]

It is of great significance for bivalve aquaculture to promote the growth through nutritional strategy. Phosphatidic acid (PA) is a potential growth-promoting nutraceutical that targets for mammalian target of rapamycin (mTOR) in vertebrates, but its role in invertebrates remains largely unknown. Here, the effects of PA on mTOR and metabolic pathways in bivalve mollusk Sinonovacula constricta were determined by intramuscular injection with di-18 : 2 PA and di-16 : 0 PA. PA (both di-18 : 2 and di-16 : 0 PA) was found to increase the glycogen concentration in the muscle of S. constricta. Di-16 : 0 PA decreased the triglyceride concentration from 0.143 ± 0.04 mmol/g protein to 0.040 ± 0.018 mmol/g protein. The concentration of Asp, Glu, Ala, Cys, Val, Met, Ile, Leu, Phe, Arg, and Pro was reduced by di-18 : 2 PA or/and di-16 : 0 PA. PA increased the mRNA level of mTOR and the phosphorylation levels of eIF4E binding protein 1 and p70S6 kinase 1. Furthermore, PA decreased the protein level of microtubule-associated protein 1 light chain 3 Ⅱ/Ⅰ and the mRNA level of AMP-activated protein kinase. The mRNA expressions of two key enzymes of glycolysis (pyruvate kinase and glucokinase) were also upregulated by both PA, while the mRNA level of glucose transporter 1 was increased by di-18 : 2 PA. Di-16 : 0 PA decreased the mRNA level of phosphoenolpyruvate carboxykinase. The mRNA levels of sterol responsive element binding protein, fatty acid synthase, and acetyl-CoA carboxylase were increased by both PA. The mRNA level of stearoyl-CoA desaturase was increased by di-18 : 2 PA. Both PA species increased the mRNA levels of key enzymes involved in tricarboxylic acid cycle (citrate synthase and NADP-isocltrate debydrogenase). Our results indicated that PA activated mTOR signaling pathway, subsequently leading to the increase of anabolism and the inhibition of catabolism in S. constricta. [ABSTRACT FROM AUTHOR]

In addition to being important primary productive forces in marine ecosystems, diatoms are also rich in bioactive substances such as triacylglycerol and fucoxanthin. However, little is known about the transcriptional mechanisms underlying the biosynthesis of these substances. In this study, we found that the heat shock transcription factor PtHSF1 positively regulated the synthesis of triacylglycerol and fucoxanthin in Phaeodactylum tricornutum. Overexpression of PtHSF1 could increase the contents of triacylglycerol and fucoxanthin and upregulate key enzyme genes involved in the triacylglycerol and fucoxanthin biosynthesis pathways. On the other hand, gene silencing of PtHSF1 reduced the contents of triacylglycerol and fucoxanthin and the expression of the key enzyme genes involved in the triacylglycerol and fucoxanthin biosynthesis pathways. Further biochemical analysis revealed that PtHSF1 upregulated glycerol-2-phosphate acyltransferase 3 (GPAT3) and 1-deoxy- d -xylulose 5-phosphate synthase (DXS) by directly binding to their promoters, while genetic analysis demonstrated that PtHSF1 acted upstream of GPAT3 and DXS to regulate triacylglycerol and fucoxanthin synthesis. Therefore, in addition to elucidating the regulation mechanisms underlying PtHSF1-mediated triacylglycerol and fucoxanthin synthesis, this study also provided a candidate target for metabolic engineering of triacylglycerol and fucoxanthin in P. tricornutum. [ABSTRACT FROM AUTHOR]

• An improved model capable of analyzing the effects of ambient gas on laser polishing is proposed. • Mass transfer, solutocapillary force, and chemical reaction are added to the model. • Convection is the main mass transfer mechanism in the molten pool, not diffusion. • The solutocapillary force always acts in the opposite direction to the melt flows. • The dissolved oxygen enhances the thermocapillary force driving the melt to flow inward. Laser polishing, as an effective surface finishing process, is significantly affected by ambient gas. Previous studies on the contribution of ambient gas to laser polishing mostly focused on experiments, but rarely on numerical simulations. Given this, this paper proposes an improved model capable of analyzing the effects of ambient gas on the laser-polished surface's morphology evolution mechanisms, by expanding an existing laser polishing model with the influences of mass transfer, solutocapillary forces, and chemical reactions. Argon and air were used as ambient gasses for comparison. Through this model, the surface morphology evolution of laser polishing in air was compared with that in argon in terms of the velocity field, temperature field, concentration field, melt surface velocity, molten pool surface profile, and surface forces. The respective contributions of chemical reaction heat, oxygen mass flux, mass transfer, and surface forces were also presented. Furthermore, the numerical model was verified on 304 stainless steel from the perspectives of polished surface roughness, molten pool depth, and oxygen element distribution. [Display omitted] [ABSTRACT FROM AUTHOR]

Ghrelin, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY) are potent hormones mediating food intake according to the nutritional status in fish. However, limited information is available on these genes and their expression in response to nutrition in silver pomfret (Pampus argenteus). A comparison analysis revealed that ghrelin and GLP-1 were relatively conserved in marine fish. PYYa and PYYb shared a low identity and were clustered to different PYY branches. Ghrelin, pyya, and pyyb mRNAs were highly expressed in the brain, while glp-1 was highly expressed in the gills and liver. The ghrelin mRNA expression was relatively high an hour post-feeding and decreased after 3 to 72 h of fasting. The glp-1 mRNA expression was increased after 6 to 24 h of fasting. The pyya mRNA expression was increased after 72 h of fasting, while the pyyb expression remained stable during fasting. The diet with 14% lipid promoted the expressions of glp-1, pyya, and pyyb, but inhibited the ghrelin expression. The ghrelin expression in the intestine was increased after palmitic acid, oleic acid (OA), linoleic acid (LA), α-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) incubation. OA decreased the expression of glp-1 and increased the expression of pyya. The expression of pyyb was downregulated by LA, DHA, and EPA. These results suggest the importance of ghrelin, glp-1, and pyy in coordinating food intake in response to fasting, dietary lipid concentration, and fatty acids in silver pomfret. [ABSTRACT FROM AUTHOR]

In recent years, the role of lectins in the feed selection of bivalve has become hot research topic. Manila clam Ruditapes philippinarum is a species of marine bivalve with important economic value. A new C-type lectin (Rpcl) from the clam was obtained and its potential role in feeding and feed selection was studied. Rpcl cDNA was 929 bp in length and had 720 bp of open reading frame. Rpcl encoded 235 amino acids, comprising a carbohydrate recognition domain (CRD) as well as an N-terminal signal peptide. Rpcl contained a conserved CRD disulfide bond including five cysteine residues (Cys125, Cys142, Cys213, Cys219, and Cys237) and the QPN motif (GLN204-PRO205-ASN206). Phylogenetic analysis revealed that the amino acid sequence of Rpcl was closely related to that of Vpclec-1 from R. philippinarum and C-type lectin from Mercenaria. The qPCR analysis indicated that Rpcl expression was observed in all examined tissues and was the highest in gills followed by in the hepatopancreas, and to a lesser extent in the mantle and lip. The in vitro agglutination experiments showed that, the purified Rpcl protein could selectively agglutinate with different microalgae. The strongest agglutinating effect with Chlorella sp. was observed, followed by Karlodinium veneficum and Chaetoceros debilis Cleve. No agglutination with Prorocentrum minimum was observed. In the feeding experiment, compared with that of the starvation group, Rpcl expression in the lip and gill of the clam fed with C. debilis and K. veneficum showed a significant upward trend with the change of time. In addition, it was found that the changes in the expression of the Rpcl gene in the gill and lip, the main feeding tissues, were consistent with the slope of the decrease in the number of algal cells in the water body. In summary, the structure of a new C-type lectin (Rpcl) was reported in this study and its correlation with the feeding and feed selection in R. philippinarum was confirmed. [ABSTRACT FROM AUTHOR]

BACKGROUND Head space solid-phase microextraction-gas chromatography-mass spectrometry has been applied to analyze the volatile components of six marine microalgae ( Thalassiosira weissflogii, Nitzschia closterium, Chaetoceros calcitrans, Platymonas helgolandica, Nannochloropsis spp . and Dicrateria inornata) from Bacillariophyta, Chlorophyta and Chrysophyta, respectively, in different growth phases. RESULTS All volatile compounds were identified by database searching in the NIST08 Mass Spectral Library and analyzed by principal component analysis with SIMCA-P software (Umetrics, Umea, Sweden). The results clearly revealed that the volatile components of the six microalgae were significantly different in the exponential, stationary and declining phases. Aldehydes, alkanes, some esters and dimethyl sulfide significantly changed in different growth phases. CONCLUSION This is the first report on the comprehensive characteristics of volatile components in different microalgae and in different growth phases. The results may provide reference data for studies on the flavor of cultivated aquatic organism, odor formation in nature water, choice of feeding period and microalgae species selection for the artificial rearing of marine organisms. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

• Porous NiMnGa alloys with large size pores are prepared by one-step sintering method. • Porous alloys with different porosities have similar phase transformation behavior. • The composite is prepared by infiltrating epoxy resin into the porous alloy. • The composite exhibits a similar phase transformation behavior to the porous alloy. • Mechanical property of the composite is effectively improved by synergistic effect. This article investigated microstructure, phase transformation and mechanical property of porous NiMnGa alloy and its composite with epoxy resin. The porous NiMnGa alloys with large pores and different porosity exhibited a similar martensitic transformation behavior but with reduced martensitic transformation temperature as compared to that of the original powder. The porous alloys exhibited low mechanical strength and ductility due to the existence of large size pores. After compositing with epoxy resin, the mechanical strength and ductility of the porous alloy had been apparently enhanced due to the synergistic effect between the polymer and porous alloy. In addition, the composite demonstrated a martensitic transformation behavior similar with that of the porous alloy, indicating that the constraint effect of polymer matrix on the phase transformation of the porous alloy could be neglected. The combination of porous NiMnGa alloys with continuous structure and polymer could provide a promising way to make NiMnGa/polymer composites with better performance than the composites consisting of NiMnGa particles and polymer. [ABSTRACT FROM AUTHOR]

Changes in membrane lipid composition play multiple roles in plant adaptation and survival in the face of chilling and freezing damage. The ultra-performance liquid chromatography/quadrupole-TOF-MS (UPLC/Q-TOF-MS)-based approach was developed for investigating the lipid changes during cold exposure in Stephanodiscus sp. followed by multivariate statistical analysis including principal components analysis, partial least squares discriminant analysis and orthogonal projection on latent structure discriminant analysis for data classification and potential biomarkers selection. The analysis demonstrated dramatic lipid alterations take place in both extraplastidic and plastidic membranes. Thirty-eight lipid molecules were selected and identified as putative biomarkers, including chlorophyll a degradation products, triacylglycerol, phosphatidylcholine, phosphatidylglycerol, sulfo-quinovosyldiacylglycerol, monogalactosyldiacylglyceroll, lyso-phosphatidylglycerol, lyso-phosphatidylcholine, lyso-monogalactosyldiacylglycerol and lyso-sulfoquinovosyldiacylglycerol. These metabolites have been shown previously to function in energy storage, membrane stability and photosynthesis efficiency. This study is the first one using UPLC/Q-TOF-MS-based lipidomic profiling with multivariate statistical analysis to explore the lipidomic changes of microalgae in response to stress conditions, which promotes better understanding of their physiology and ecology. [ABSTRACT FROM AUTHOR]

A facile method based on high performance liquid chromatography coupled with electrospray ionization tandem triple quadrupole mass spectrometry (HPLC-ESI-QqQ-MS) has been established to investigate the production of the oxidized scytonemin by Nostoc commune Vauch in different environmental conditions. In optimized HPLC-ESI-QqQ-MS conditions, the oxidized scytonemin can be effectively detected in selected reaction monitoring (SRM) mode. After regression, high linearity of the calibration curve was achieved with a correlation coefficient ( r) at 0.99. The limit of detection and limit of quantification were 0.03 and 0.10 ng mL, respectively. The recovery of the oxidized scytonemin was at 76.90 %, and the relative standard deviations of inter- and intraday precisions were lower than 8.95 % ( n = 4). Subsequently, the production of the oxidized scytonemin from N. commune has been investigated in different culture conditions. High culture temperature, strong illumination intensity, and light-dark cycle (12:12 h) were found to be good for producing the oxidized scytonemin by N. commune. In short, the HPLC-QqQ-SRM-MS method is a powerful tool for comprehensive analysis of the oxidized scytonemin from N. commune, owing to its excellent selectivity and sensitivity. [ABSTRACT FROM AUTHOR]

The razor clam Sinonovacula constricta is known for its richness in long-chain polyunsaturated fatty acids (LC-PUFA, C ≥ 20). Previously, we demonstrated that it possesses a complete LC-PUFA biosynthetic pathway. However, the mechanisms by which it senses the LC-PUFA pool to regulate their biosynthesis remain unclear. Here, we presented the LC-PUFA sensor UBXD8 as a critical molecule in this intriguing process. The S. constricta UBXD8 (Sc UBXD8) shared all characteristic features of its mammalian counterpart and exhibited high mRNA levels in digestive tissues, suggesting its functional role in this bivalve species. By purification of Sc UBXD8 protein in vitro , we discovered its ability to sense unsaturated fatty acids (UFA, C ≥ 14) but not saturated ones, as evidenced by polymerization detection. Furthermore, the intensity of Sc UBXD8 polymerization increased progressively with longer acyl chain lengths, greater unsaturation degrees, and higher UFA concentrations. Exceptionally, for those located at the same node in LC-PUFA biosynthetic pathway, Sc UBXD8 displayed a stronger sensitivity to n-6 UFA compared to n-3 UFA. These results suggested a critical role for Sc UBXD8 in balancing fatty acids composition and ratio of n-6/n-3 UFA in S. constricta. Moreover, the UAS domain was confirmed essential for Sc UBXD8 polymerization. Through knockdown of Sc Ubxd8 gene in vivo , there were significant shifts in expression patterns of genes related to LC-PUFA biosynthesis, concurrently influencing fatty acids compositions. These results suggested that Sc UBXD8 likely plays a regulatory role in LC-PUFA biosynthesis, possibly through the INSIG-SREBP pathway. Collectively, this study proposed that S. constricta might maintain LC-PUFA homeostasis through UBXD8 to regulate their biosynthesis. • Characteristics of S. constricta UBXD8 (Sc UBXD8) were evolutionarily conserved. • Sc UBXD8 displayed ability to sense unsaturated fatty acids but not saturated ones. • Knocking down Sc Ubxd8 significantly disrupted LC-PUFA synthesis in S. constricta. • Knocking down Sc Ubxd8 significantly altered fatty composition in S. constricta. • S. constricta might sense LC-PUFA pool through UBXD8 to maintain homeostasis. [ABSTRACT FROM AUTHOR]

Abstract: La0.1Nd0.1Y1.8O3 transparent ceramics nanopowders were prepared using the combustion synthesis. To achieve such transparent ceramics, Y2O3 were used as matrix materials and La3+ and Nd3+ were used as dopants, polyethyleneglycol (PEG) as dispersants for the sintering under vacuum 10−3 Pa and 1600°C for 6h. The precursor and powders calcined at different temperatures were characterized using TG-DTA, XRD, BET and FESEM. The transmittance of the transparent ceramics was measured using the sub-photometer. Results showed that La3+ and Nd3+ were completely dissolved into the cubic lattice of Y2O3. The sizes of Y1.8La0.1Nd0.1O3 powders were uniform and spherical-like. The particle sizes of powders gradually increased with increasing the calcination temperature. The dispersant can effectively prevent the powders from the agglomeration, and the particle sizes of powders gradually increased with increasing citric acid. The transmittance of the Y1.8La0.1Nd0.1O3 transparent ceramics was close to its theoretical value (80%). [Copyright &y& Elsevier]

The nanoporous Ni-based solid solution electrode inspired by mimicking the components of natural Gibeon meteorites fallen from the sky brings favourable electrochemical and mechanical performances for the oxygen evolution reaction in alkaline medium. This study provide a promising low-cost and environment-friendly approach to prepare nanoporous architectures based on non-precious metal solid solutions for high-efficiency water electrolysis towards large-scale utilization of clean hydrogen energy. • Nanoporous Ni-based solid solution by Mimicking Natural Gibeon Meteorites. • An metal oxyhydroxide layer of approximately 9 nm thickness for the OER. • Robust electrochemical and mechanical performance for the OER in alkaline medium. Transforming the intermittent solar and wind energies into green hydrogen energy by water electrolysis is deemed to be a promising approach to substitute traditional fossil energies. However, the scarcity of precious IrO 2 /RuO 2 -based metal oxides for oxygen evolution reaction hinders the large-scale utilization. Here, based on the nanoscale Kirkendall effect, we fabricate nanoporous γ-Ni based solid solution with the simulated FeCoNi surface compositions of Gibeon meteorites by a facile microwave sintering method. A metal (oxy)hydroxide layer with a thickness of approximately 9 nm was formed on the surface of as-prepared electrode after aging, achieving an overpotential of only 254 mV at 10 mA cm−2 and a low Tafel slope of 37.0 mV dec−1. The electrode exhibits outstanding long-term stability in a wide range of current densities without compromising the electrocatalytic activity, which is attributed to the 3D-interconnected nanoporous structure, synergistic effect of different species, high conductivity and excellent wettability. The fabrication of nanoporous non-precious solid solution architectures which mimic naturally-formed materials provides a feasible strategy for the design of high-performance electrocatalysts towards clean energy applications. [ABSTRACT FROM AUTHOR]

The nutritional requirements and metabolism of bivalves remain largely unknown. In this study, we investigated the effects of dietary carbohydrate/lipid ratios on growth performance, body composition, digestive enzyme activities, oxidative status, and transcriptome profile in juvenile razor clam Sinonovacula constricta. Five microcapsule diets with varying levels of carbohydrate (30–45%) and lipid (2–15%) were prepared and designated as C45L2 (45% carbohydrate and 2% lipid), C41L5, C36L8, C33L11, and C30L15 groups. Juvenile S. constricta with an initial shell length of 4.9 mm were fed with these microcapsule diets for 2 weeks. The results showed that the clam in the C33L11 group exhibited the fastest growth rate. The body protein content decreased with the decreasing dietary carbohydrate/lipid ratio. The clam in the C33L11 group showed significantly higher glycogen content compared to the C45L2, C41L5, or C30L5 group. The amylase activity of the clam in the C45L2 and C41L5 group was significantly higher than that in the C36L8, C33L11, and C30L15 group. The clam in the C33L11 group showed significantly higher catalase and superoxide dismutase activities compared to other microcapsule groups. The malondialdehyde level of the clam in the C30L15 group was significantly higher than that in the C45L2, C41L5, and C33L11 group. Transcriptome analysis showed that the autophagy pathway in the clam fed C41L5 was upregulated compared with those fed C33L11. Meanwhile, the protein levels of microtubule-associated protein 1 A/1B-light chain 3 membrane type (LC3-II) in the C41L5 group were also significantly higher than those in the C33L11 group. Moreover, the clam in the C41L5 group exhibited increased phosphorylation levels of the eukaryotic translation initiation factor 4E-binding protein (4E-BP) and decreased phosphorylation levels of the ribosomal protein S6 kinase beta-1 (S6K). Our results revealed that the optimal dietary carbohydrate/lipid ratio for juvenile S. constricta was approximately 3.01. The high-carbohydrate/low-lipid diet may repress the growth of clam by inhibiting mammalian target of rapamycin complex 1 (mTORC1) and subsequently activating autophagy, while the poor growth performance in the low-carbohydrate/high-lipid diet group may be associated with high lipid peroxidation levels in juvenile S. constricta. • The optimal carbohydrate/lipid ratio for juvenile S. constricta was about 3.01. • The body protein content was decreased with the decline of carbohydrate/lipid ratio. • Amylase activity increased with the increase of dietary carbohydrate. • Fit carbohydrate/lipid ratio enhanced SOD, CAT activities, and lower carbohydrate to lipid ratio increased MDA level. • Compared to C33L11 diet, C41L5 diet might lead to autophagy through mTORC1 pathway. [ABSTRACT FROM AUTHOR]

Carotenoids consist of a series of conjugated isoprene units that are characteristically highly conjugated through double bonds, leading to the formation of many isomers that are susceptible to oxidation and other chemical modifications. Extreme hydrophobicity and high complexity make carotenoids difficult to identify and quantify. We implemented the use of a common Syncronis C18 column with strong eluting solvent, here isopropanol, to successfully separate a mixture of 23 carotenoids standards with different structural properties. In addition, the method differentiated between three groups of isomeric carotenoids (lycopene/δ‐carotene/γ‐carotene/ε‐carotene/α‐carotene/β‐carotene, α‐cryptoxanthin/β‐cryptoxanthin, and zeaxanthin/lutein) by optimizing the gradient profile and using liquid chrmatography–mass spectrometry. The LOD ranged from 0.05 to 5.51 ng/mL, and the recovery of carotenoids in Mytilus coruscus was from 63.54 to 93.25%, with standard deviations <10%. Twenty‐five carotenoids were detected with a total content of 857 ± 55.1 mg/kg, and three isomeric carotenoids were identified: ε‐carotene, α‐carotene, and β‐carotene. Our results show that this methodology is a significant improvement over other alternatives for analyzing carotenoids because of its compatibility with carotenoids of different categories, and most importantly, its ability to resolve isomeric carotenes, which is significant not only for assessing carotenoid species, but also for the tracing of metabolic pathways of carotenoids. [ABSTRACT FROM AUTHOR]

Bivalve lectins perform a crucial function in recognition of foreign particles, such as microalgae and pathogenic bacteria. In this study, a novel C-type lectin form Sinonovacula constricta (ScCL) was characterized. The full-length cDNA of ScCL was 1645 bp, encoding a predicted polypeptide of 273 amino acids with one typical carbohydrate-recognition domain. ScCL has the highest similarity and closest phylogenetic relationship with the C-type lectin from Solen grandis. Real-time PCR analysis showed that ScCL was expressed in all tested tissues, with the highest expression in the foot and the lowest expression in hemocytes. Agglutination activity of ScCL was Ca2+-independent. ScCL showed the strongest agglutination on Chlorella vulgaris , the modest agglutination on Platymonas subcordiformis , Nannochloropsis sp., and Thalassiosira pseudonana , the weakest agglutination on Chaetoceros sp., and no agglutination on Isochrysis zhanjiangensis. Meanwhile, agglutination tests and western blot analysis revealed that the recombinant ScCL protein could agglutinate Staphylococcus aureus and Vibrio harveyi , but could not agglutinate Vibrio anguillarum , Bacillus cereus , or Vibrio parahaemolyticus. Furthermore, ScCL had a high binding activity with LPS and mannose, a low binding activity with LTA, and no binding activity with PGN. The expression of ScCL in the gill of S. constricta fed with C. vulgaris and T. pseudonana was significantly increased at 1 and/or 3 h. After injection with S. aureus , the expression of ScCL in the gill was significantly increased at 3, 6, and 24 h. These results indicated that ScCL was involved in food particle recognition and immunity of S. constricta. • A novel C-type lectin from Sinonovacula constricta (ScCL) was characterized. • ScCL protein could bind to several PAMPs and bacteria. • ScCL protein could agglutinate several microalgae and bacteria in Ca2+-independent. • After feeding Chlorella vulgaris and Thalassiosira pseudonana , or after challenged with staphylococcus aureus , the expression of ScCL was up-regulated. • ScCL may be involved in food recognition and innate immunity. [ABSTRACT FROM AUTHOR]

Abstract: Yttrium oxide (Y2O3) transparent ceramics samples have been successfully fabricated by microwave sintering processing at relatively low temperatures. In comparison with the vacuum sintering processing, Y2O3 transparent ceramics can be obtained by microwave sintering at lower sintering temperature and shorter sintering time, and they possess higher transmittances and mechanical properties. The technologies of low-temperature microwave sintering and the relationships of the microstructures and properties of the specified samples have been investigated in detail. We have found out that the low-temperature microwave sintering technique has its obvious advantages over the conventional methods in manufacturing yttrium oxide transparent ceramics. [Copyright &y& Elsevier]