Showing papers by "Ocean University of China published in 2009"

New developments in fish amino acid nutrition: towards functional and environmentally oriented aquafeeds

Abstract: Recent evidence shows that some amino acids and their metabolites are important regulators of key metabolic pathways that are necessary for maintenance, growth, feed intake, nutrient utilization, immunity, behavior, larval metamorphosis, reproduction, as well as resistance to environmental stressors and pathogenic organisms in various fishes. Therefore, conventional definitions on essential and nonessential amino acids for fish are challenged by numerous discoveries that taurine, glutamine, glycine, proline and hydroxyproline promote growth, development, and health of aquatic animals. On the basis of their crucial roles in cell metabolism and physiology, we anticipate that dietary supplementation with specific amino acids may be beneficial for: (1) increasing the chemo-attractive property and nutritional value of aquafeeds with low fishmeal inclusion; (2) optimizing efficiency of metabolic transformation in juvenile and sub-adult fishes; (3) surpressing aggressive behaviors and cannibalism; (4) increasing larval performance and survival; (5) mediating timing and efficiency of spawning; (6) improving fillet taste and texture; and (7) enhancing immunity and tolerance to environmental stresses. Functional amino acids hold great promise for development of balanced aquafeeds to enhance the efficiency and profitability of global aquaculture production.

Mechanical and thermal properties of chicken feather fiber/PLA green composites

Abstract: Chicken feather fiber (CFF)/reinforced poly(lactic acid) (PLA) composites were processed using a twin-screw extruder and an injection molder. The tensile moduli of CFF/PLA composites with different CFF content (2, 5, 8 and 10 wt%) were found to be higher than that of pure PLA, and a maximum value of 4.2 GPa ( 16 % ↑ ) was attained with 5 wt% of CFF without causing any substantial weight increment. The morphology, evaluated by scanning electron microscopy (SEM), indicated that an uniform dispersion of CFF in the PLA matrix existed. The mechanical and thermal properties of pure PLA and CFF/PLA composites were compared using dynamic mechanical analysis (DMA), thermomechanical analysis (TMA) and thermogravimetric analysis (TGA). DMA results revealed that the storage modulus of the composites increased with respect to the pure polymer, whereas the mechanical loss factor (tan δ ) decreased. The results of TGA experiments indicated that the addition of CFF enhanced the thermal stability of the composites as compared to pure PLA. The outcome obtained from this study is believed to assist the development of environmentally-friendly composites from biodegradable polymers, especially for converting agricultural waste – chicken feather into useful products.

Scattering by pure seawater: Effect of salinity

Abstract: A theoretical model was developed estimating the scattering by seawater that are due to concentration fluctuation. Combining with the model proposed for density fluctuation (Optics Express, 17, 1671, 2009), we evaluated the overall effect of sea salts on the scattering. The variation of seawater scattering with the salinity is a combination of two factors: decreasing contribution due to density fluctuation and increasing contribution due to concentration fluctuation, with the latter effect dominating. The trend is, however, slightly non-linear and the linear adjustment of scattering with salinity that is frequently used would lead to an underestimate by an average of 2%. The results estimated at S = 38.4‰ agree with the measurements by Morel (Cahiers Oceanographiques, 20, 157, 1968) with an average difference of 1%, well within his experimental error of 2%. The spectral signature also varies with salinity, with the power-law slope increasing from -4.286 to -4.306 for salinity from 0 to 40‰.

Effect of sub-acute exposure to TiO2 nanoparticles on oxidative stress and histopathological changes in Juvenile Carp (Cyprinus carpio).

Abstract: Increasing application of nanotechnology highlights the need to clarify and understand nanotoxicity. Mammalian and in vitro studies have raised concerns about the toxicity of titanium dioxide nanoparticles (TiO2-NPs), but there are limited data on ecotoxicity to aquatic organisms. In this work, the sub-acute toxicity of TiO2-NPs to carp (Cyprinus carpio) was assessed. Superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities and lipid peroxidation (LPO) levels in liver, gill and brain tissues of carps varied with concentration of TiO2-NPs suspensions and exposure time (up to 8 d). As a result, 100 and 200 mg/L TiO2-NPs caused statistically significant decrease in SOD, CAT and POD activities and significant increase in LPO levels in tissues (P < 0.05), suggesting that the fish exposed to these two concentrations of TiO2-NPs suffered from the oxidative stress. The extent of depletion of antioxidant enzymes activities and the elevation of LPO in the liver was the greatest, indicating that the liver might be the most susceptible organ to TiO2-NPs exposure. In addition, carps had gill pathologies including edema and thickening of gill lamellae as well as gill filaments, and liver pathologies including necrotic and apoptosis hepatocytes after exposed to 100 and 200 mg/L TiO2-NPs for 20 d. These results indicated a potential risk from TiO2-NPs released into the aqueous environment.

Nutrient budgets for large Chinese estuaries

Abstract: . Chinese rivers deliver about 5–10% of global freshwater input and 15–20% of the global continental sediment to the world ocean. We report the riverine fluxes and concentrations of major nutrients (nitrogen, phosphorus, and silicon) in the rivers of the contiguous landmass of China and Korea in the northeast Asia. The rivers are generally enriched with dissolved inorganic nitrogen (DIN) and depleted in dissolved inorganic phosphate (PO43−) with very high DIN: PO43− concentration ratios. DIN, phosphorus, and silicon levels and loads in rivers are mainly affected by agriculture activities and urbanization, anthropogenic activities and adsorption on particulates, and rock types, climate and physical denudation intensity, respectively. Nutrient transports by rivers in the summer are 3–4 times higher than those in the winter with the exception of NH4+. The flux of NH4+ is rather constant throughout the year due to the anthropogenic sources such as the sewer discharge. As nutrient composition has changed in the rivers, ecosystems in estuaries and coastal sea have also changed in recent decades. Among the changes, a shift of limiting nutrients from phosphorus to nitrogen for phytoplankton production with urbanization is noticeable and in some areas silicon becomes the limiting nutrient for diatom productivity. A simple steady-state mass-balance box model was employed to assess nutrient budgets in the estuaries. The major Chinese estuaries export

Inulinase-expressing microorganisms and applications of inulinases

Abstract: In this review article, inulinase-expressing microorganisms and its potential applications in transformation of inulin into very-high-fructose syrup, bioethanol, and inulooligosaccharides are overviewed. In the past 10 years, many new inulinase producers have been obtained and many genes encoding inulinases from different microorganisms have been cloned and characterized. Some novel processes for exoinulinase overproduction have been developed for bioethanol production and ultra-high-fructose syrup. The endoinulinases have also been used for production of inulooligosaccharides from inulin and inulin-containing materials.

MSMOTE: Improving Classification Performance When Training Data is Imbalanced

Abstract: Learning from data sets that contain very few instances of the minority class usually produces biased classifiers that have a higher predictive accuracy over the majority class, but poorer predictive accuracy over the minority class. SMOTE (Synthetic Minority Over-sampling Technique) is specifically designed for learning from imbalanced data sets. This paper presents a modified approach (MSMOTE) for learning from imbalanced data sets, based on the SMOTE algorithm. MSMOTE not only considers the distribution of minority class samples, but also eliminates noise samples by adaptive mediation. The combination of MSMOTE and AdaBoost are applied to several highly and moderately imbalanced data sets. The experimental results show that the prediction performance of MSMOTE is better than SMOTEBoost in the minority class and F-values are also improved.

Bioproducts from Aureobasidium pullulans, a biotechnologically important yeast.

Abstract: It has been well documented that Aureobasidium pullulans is widely distributed in different environments. Different strains of A. pullulans can produce amylase, proteinase, lipase, cellulase, xylanase, mannanase, transferases, pullulan, siderophore, and single-cell protein, and the genes encoding proteinase, lipase, cellulase, xylanase, and siderophore have been cloned and characterized. Therefore, like Aspergillus spp., it is a biotechnologically important yeast that can be used in different fields. So it is very important to sequence the whole genomic DNA of the yeast cells in order to find new more bioproducts and novel genes from this yeast.

Seasonal response of Asian monsoonal climate to the Atlantic Multidecadal Oscillation

Abstract: [1] The influence of the Atlantic Multidecadal Oscillation (AMO) on Asian monsoonal climate in all four seasons is investigated by comprehensive observational analyses and ensemble experiments with atmospheric general circulation models (AGCMs). Three AGCMs are forced by prescribed climatological seasonal cycle of sea surface temperature (SST) or with additional SST anomalies representing the warmth phase of the AMO. The results in both the observations and the models consistently suggest that the warm AMO phase gives rise to elevated air temperatures in East Asia and northern India but decreased air temperatures in much of central-southern India in all four seasons. This positive AMO anomaly also causes more rainfall in central and southern India in every season, particularly in summer and fall. In contrast, the sign of AMO influences on East Asian rainfall is season-dependent: in southeastern China, it induces increased rainfall in summer but suppressed rainfall in autumn. It is suggested that these AMO influences are realized by warming Eurasian middle and upper troposphere in all four seasons, resulting in weakened Asian winter monsoons but enhanced summer monsoons. Furthermore, the formation of the troposphere heating anomaly may be related to the wave guidance mechanism associated with the Asian upper jet.

A novel advanced oxidation process to degrade organic pollutants in wastewater: microwave-activated persulfate oxidation.

Abstract: This article, for the first time, provides a novel advanced oxidation process based on sulfate radical (SO 4 •− ) to degrade organic pollutants in wastewater: microwave (MW)-activated persulfate oxidation (APO) with or without active carbon (AC). Azo dye acid Orange 7 (AO7) is used as a model compound to investigate the high reactivity of MW-APO. It is found that AO7 (up to 1000 mg/L) is completely decolorized within 5–7 min under an 800 W MW furnace assisted-APO. In the presence of chloride ion (up to 0.50 mol/L), the decolorization is still 100% completed, though delayed for about 1–2 min. Experiments are made to examine the enhancement by AC. It is exciting to find that the 100% decolorization of AO7 (500 mg/L) is achieved within 3 min by MW-APO using 1.0 g/LACas catalyst, while the degradation efficiency maintains at 50% by MW energy without persulfate after about 5 min. Besides the destruction of visible light chromophore band of AO7 (484 nm), during MW-APO, two bands in the ultraviolet region (228 nm and 310 nm) are rapidly broken down. The removal of COD is about 83%–95% for 500 mg/L AO7. SO 4 •− is identified with quenching studies using specific alcohols. Both SO 4 •− and ·OH could degrade AO7, but SO 4 •− plays the dominant role. In a word, MW-APO AC is a new catalytic combustion technology for destruction of organic contamination even for high concentration.

Enhanced Diapycnal Mixing in the South China Sea

Abstract: Profiles of current velocity, temperature, and salinity were obtained in the Internal Wave and Mixing Experiment in the South China Sea (SCS), the Luzon Strait, and the North Pacific. The observations are examinedforevidenceofenhanceddiapycnalmixingintheSCS,whichreachesO(10 23 m 2 s 21 ) inmagnitude. Resultsfrom independent casts reveal that diapycnal diffusivity in the SCS andthe Luzon Strait is elevatedby two orders of magnitude over that of the smooth bathymetry in the North Pacific, which are typical of background values in an open ocean. The vertical distribution of diapycnal diffusivity is nonuniform in the SCS, exhibiting higher values at depths greater than about 1000 m. This result compares favorably with the direct microstructure measurements at four stations in the SCS. Velocity and density profiles are combined to estimatetheinternaltideenergyfluxgeneratedintheLuzonStraitanddirectedintotheSCS. Theenergyamounts to 10 GW, most of which is rationalized to be the potential energy source for enhanced mixing in the SCS.

Photocatalyst of TiO2/ZnO nano composite film: Preparation, characterization, and photodegradation activity of methyl orange

Abstract: The TiO 2 /ZnO nano composite film with atomic ratios of Ti/(Ti + Zn) of 100%, 75%, 50%, 25%, and 0% was successfully prepared via sol–gel process from directly mixing TiO 2 /ZnO sol followed by heat treatment at 500 °C for 2 h in air. The SEM observation and the XRD measurement revealed that the microstructural morphology and the crystallization behavior of the composite film were essentially related to the atomic ratio of Ti/(Ti + Zn). The UV irradiated degradation of MO solution using the composite film as catalyst showed a linear tendency of the photocatalytic activity of the film against the value of Ti/(Ti + Zn). An exception to photocatalytic activity was observed for the film with Ti/(Ti + Zn) of 75%, which has been attributed to the poor crystallization of the film. Heat treatment with 5 h was applied to the film and better crystallization was achieved for the film. Consequently, a substantial improvement of the photocatalytic activity for the film was finally achieved.

Effects of collagen and collagen hydrolysate from jellyfish (Rhopilema esculentum) on mice skin photoaging induced by UV irradiation.

Abstract: Collagen (JC) was extracted from jellyfish (Rhopilema esculentum) and hydrolyzed to prepare collagen hydrolysate (JCH). The protective effects of JC and JCH against UV-induced damages to mice skin were evaluated and compared in this article. JC and JCH could alleviate the UV-induced abnormal changes of antioxidative indicators, including the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities and the contents of glutathione (GSH) and malondiaidehyde (MDA). JC and JCH could protect skin lipid and collagen from the UV radiation damages. Furthermore, the changes of total ceramide and glycosaminoglycan in skin were recovered significantly by JC and JCH. The action mechanisms mainly involved the antioxidative properties and the repairing to endogenous collagen synthesis of JC and JCH in vivo. JCH with the lower molecular weight showed much higher effects than JC. The results indicated that JCH was a novel antiphotoaging agent from natural resources.

Covariant light-front approach for B c transition form factors

Abstract: In the covariant light-front quark model, we investigate the form factors of ${B}_{c}$ decays into $D$, ${D}^{*}$, ${D}_{s}$, ${D}_{s}^{*}$, ${\ensuremath{\eta}}_{c}$, $J/\ensuremath{\psi}$, $B$, ${B}^{*}$, ${B}_{s}$, and ${B}_{s}^{*}$ mesons. The form factors in the spacelike region are directly evaluated. To extrapolate the form factors to the physical region, we fit the form factors by adopting a suitable three-parameter form. At the maximally recoiling point, $b\ensuremath{\rightarrow}u$, $d$, and $s$ transition form factors are smaller than $b\ensuremath{\rightarrow}c$ and $c\ensuremath{\rightarrow}d$, $s$ form factors, while the $b\ensuremath{\rightarrow}u$, $d$, $s$, and $c$ form factors at the zero-recoiling point are close to each other. In the fitting procedure, we find that parameters in ${A}_{2}^{{B}_{c}{B}^{*}}$ and ${A}_{2}^{{B}_{c}{B}_{s}^{*}}$ strongly depend on decay constants of ${B}^{*}$ and ${B}_{s}^{*}$ mesons. Fortunately, semileptonic and nonleptonic ${B}_{c}$ decays are not sensitive to these two form factors. We also investigate branching fractions, polarizations of the semileptonic ${B}_{c}$ decays. ${B}_{c}\ensuremath{\rightarrow}({\ensuremath{\eta}}_{c},J/\ensuremath{\psi})l\ensuremath{ u}$ and ${B}_{c}\ensuremath{\rightarrow}({B}_{s},{B}_{s}^{*})l\ensuremath{ u}$ decays have much larger branching fractions than ${B}_{c}\ensuremath{\rightarrow}(D,{D}^{*},B,{B}^{*})l\ensuremath{ u}$. For the three kinds of ${B}_{c}\ensuremath{\rightarrow}Vl\ensuremath{ u}$ decays, longitudinal contributions are comparable with the transverse contributions. These predictions will be tested on the ongoing and forthcoming hadron colliders.

Metal complexation by humic substances in seawater.

Abstract: We determined the complex stability of copper, zinc, cobalt, and aluminum with humic acid (HA) and fulvic acid (FA) in pH 8 seawater. The method is based on metal competition against iron, for which the complex stability with humic substances (HS) in seawater had been calibrated previously against EDTA. The conditional stability constants, log K′Mn+HS values, were found to decrease in the order of Cu > Zn > Co and Fe > Al. The complex stability of the HA species was greater than the FA species, but all determined complex stabilities are sufficiently high for significant complexation of the examined metals by HS in seawater. Data modeling shows a good data fit over the entire titrations for Cu and Co and for low levels of Zn. A second site on the HS appears to bind higher levels of Zn. The Al data suggest that Fe is exchanged for Al at a ratio different from 1:1. The data suggests that HS may be an important ligand for these metals in seawater.