A ratiometric fluorescent probe for hypoxanthine detection in aquatic products based on the enzyme mimics and fluorescence of cobalt-doped carbon nitride

A ratiometric fluorescent probe for hypoxanthine(Hx)detection was established based on the mimic enzyme and fluorescence characteristics of cobalt-doped graphite-phase carbon nitride(Co doped g-C_(3)N_(4)).In addition to emitting strong fluorescence,the peroxidase activity of Co doped g-C_(3)N_(4)can catalyze the reaction of O-phenylenediamine and H_(2)O_(2)to produce diallyl phthalate which can emit yellow fluorescence at 570 nm.Through the decomposition of Hx by xanthine oxidase,Hx can be indirectly detected by the generating hydrogen peroxide based on the measurement of fluorescent ratio I(F_(570)/F_(370)).The linear range was 1.7-272.2 mg/kg(R^(2)=0.997),and the detection limit was 1.52 mg/kg(3σ/K,n=9).The established method was applied to Hx detection in bass,grass carp,and shrimp,and the data were verified by HPLC.The result shows that the established probe is sensitive,accurate,and reliable,and can be used for Hx detection in aquatic products.

Cumulative Risk Assessment of Exposure to Heavy Metals through Aquatic Products in China

Objective This study aimed to assess the risk of cumulative exposure to Pb,Cd,Hg,and iAs through aquatic products consumed by Chinese people.Methods Heavy metal concentration data were obtained from the national food contamination monitoring program during 2013–2017.Consumption data were derived from the China National Food Consumption Survey in 2014 and the relative potency factor(RPF)method was used to estimate cumulative exposure for neurotoxicity and nephrotoxicity.Results The results demonstrated that the cumulative exposure based on neurotoxicity was below the lower confidence limit on benchmark doses of lead(BMDL01)for nephrotoxicity and the cumulative exposures were all lower than the provisional tolerable monthly intake(PTMI)of Cd.However,the margin of exposure values(MOEs)of the cumulative exposures for neurotoxicity in the 2–6 year-old group was close to 1 and the cumulative exposure level for nephrotoxicity accounted for 90.21%of the PTMI.Conclusion The cumulative exposures of the 2–6 year-old group to the four heavy metals did not reach(but came close to)the corresponding safety threshold for both neurotoxicity and nephrotoxicity.Given that there are still other food sources of these four heavy metals,it is necessary to more closely study their cumulative health effects.

The Research Progress of Endogenous Formaldehyde in Aquatic Products

Endogenous formaldehyde in aquatic products is a hot research topic, as it is an urgent problem to be solved. This paper summarized the advance in background concentration, generation mechanism and detection methods of endogenous formaldehyde in aquatic products, and the work in the future was prospected.

Research Progress of Low Temperature Preservation Technology for Aquatic Products

Aquatic products are highly perishable because of the biological characteristics.So it is very important to study the preservation of aquatic products.Low temperature preservation technology is the earliest and most widely used technology.This paper introduced the research progress of low temperature preservation technology for aquatic products at home and abroad,and pointed out some problems and the future development trend of low temperature preservation.It provides a basis for the development of the aquatic product processing.

The Price Model of Aquatic Products Based on Predictive Control Theory

This paper discusses a disequilibrium cobweb model of price of aquatic products, and applies predictive control theory, so that the system operates stably, and the deviation between supply and demand of aquatic products smoothly tracks the pre-given target. It defines the supply and demand change model, and researches the impact of parameter selection in this model on dynamic state and robustness of the system. I conduct simulation by Matlab software, to get the response curve of this model. The results show that in the early period of commodities coming into the market, affected by lack of market information and many other factors, the price fluctuates greatly in a short time. The market will gradually achieve balance between supply and demand over time, and the price fluctuations in the neighbouring two periods are broadly consistent. The increase in model parameter can decrease overshoot, to promote the stability of system, but the slower the dynamic response, the longer the deviation between supply and demand to accurately track a given target. Therefore, by selecting different parameters, the decision-makers can establish different models of supply and demand changes to meet the actual needs, and ensure stable development of market. Simulation results verify the excellent performance of this algorithm.

Differentiated Brand Marketing Strategy for China's Conventional Aquatic Products

The volume of production and marketing of China's conventional aquatic products is increasing. Compared with price of livestock and poultry products,price of conventional aquatic products is relatively low. Differentiated brand marketing for China's conventional aquatic products is a key approach for increasing market demand for conventional aquatic products and increasing value of conventional aquatic products. The differentiated brand marketing is an inevitable trend of market development and also a powerful arm for market competition. China's conventional aquatic products can take differentiated brand marketing strategies such as brand orientation,brand concept,brand culture,and place name brand,to better keep market competitive edge and increase economic benefits.

Accumulation Characteristics and Safety Evaluation of Heavy Metals in Four Kinds of Aquatic Products from Lake Taihu

In order to investigate the current status of heavy metals pollution and food safety of aquatic products from Lake Taihu,atomic absorption spectrophotometry( AAS) was used to determine the contents of Pb,Cd,Cu,and Zn in the head,muscle and viscera of farmed and wild aquatic products. The results showed that the distribution patterns of heavy metals in different parts of aquatic products were quite different. Heavy metals were mainly distributed in the head and viscera of all investigated aquatic products except wild Carassius auratus. The contents of heavy metals in each part of aquatic products generally decreased in the following order: Zn > Cu > Pb > Cd. The levels of heavy metals pollution in the muscle tissue of farmed and wild aquatic products were different,with higher levels being found in the muscle tissue of wild aquatic products. Furthermore,the content of each heavy metal in muscle tissue was also different among different kinds of aquatic products,with both farmed and wild Metapenaeus ensis having the strongest Cu accumulation capacity while wild C. auratus having the strongest Zn accumulation capacity. The heavy metals pollution in the muscle tissue of aquatic products from Lake Taihu was generally at unpolluted to minor pollution level,and only a few of them were seriously polluted with heavy metals. The main pollution factors were Pb and Zn.

Contents of Heavy Metals in Typical Aquatic Products from a Market in Binzhou

To evaluate the levels of heavy metal pollution and risks in consumption of aquatic products from a market in Binzhou,the contents of Cu,Zn,Cd,Cr and Pb in the edible part of eight aquatic species such as Ctenopharyngodon idellus were determined by inductively coupled plasma mass spectrometry.The results show that the levels of the five elements differed among different species of aquatic products.The ability of bivalves to accumulate heavy metals was significantly higher than that of fish.Compared with relevant food hygiene standards,there was a certain excess of Cr in Ruditapes philippinarum and Penaeus vannamei.The results of human exposure risk assessment show that the THQ values of the heavy metals in the eight aquatic species were all less than 1,indicating that the consumption of these aquatic products had no potential non-carcinogenic risks.

Determination of Selenium in Marine Aquatic Products by Hydride Generation-atomic Fluorescence Spectrometry (HG-AFS)

A method for the analysis of selenium in marine aquatic products by HG-AFS has been investigated. The methodis based on the reduction of inorganic selenium to volatile SeH2 which is bubbled out by carrier gas of pure argon, and thenswept to Ar-H2 flame quarts atomizer to measure its fluorescence intensity. The hydride generation, transportation, atom-ization and some instrumental parameters were studied by a kind of orthogonal design. The optimum conditions selected areas follows: reactive acidity, 20% HCl; the amount of NaBH4, 4.9mL; gas flow of argon, 600mLmin-1; atomizing tempera-ture, 200 °C; negative high voltage, -300V; light current, 100 mA; integral time, 7s. The detection limit of the presentedmethod is 0.072 μg L-1 for selenium. The calibration curve shows a satisfactory line in the concentration range from 0.000 to1.000 μg L-1 Se. The recovery is 95.8%-102.2% .

Application of Gray Metabolic GM (1,1) Model in Prediction of Annual Total Yields of Chinese Aquatic Products

To predict the annual total yields of Chinese aquatic products in future five years ( 2011-2015) ,based on the theory and method of gray system,this paper firstly establishes a conventional GM ( 1,1) model and a gray metabolic GM ( 1,1) model respectively to predict the annual total yields of Chinese aquatic products in 2006-2009 and compare the prediction accuracy between these two models. Then,it selects the model with higher accuracy to predict the annual total yields of Chinese aquatic products in future five years. The comparison indicates that gray metabolic GM ( 1,1) model has higher prediction accuracy and smaller error,thus it is more suitable for prediction of annual total yields of aquatic products. Therefore,it adopts the gray metabolic GM ( 1,1) model to predict annual total yields of Chinese aquatic products in 2011-2015. The prediction results of annual total yields are 55. 32,57. 46,59. 72,62. 02 and 64. 43 million tons respectively in future five years with annual average increase rate of about 3. 7% ,much higher than the objective of 2. 2% specified in the Twelfth Five-Year Plan of the National Fishery Development ( 2011 to 2015) . The results of this research show that the gray metabolic GM ( 1,1) model is suitable for prediction of yields of aquatic products and the total yields of Chinese aquatic products in 2011-2015 will totally be able to realize the objective of the Twelfth Five-Year Plan.

A Critical Review on Superchilling Preservation Technology in Aquatic Product

aquatic product, known as one of the good resources for white meat, has been widely accepted by the consumers due to its high protein, low fat, especially low cholesterol. With the fast development of living standards around the world, the consumer demands for high quality, nutrition, safety and freshness of ifshery food are increasing. Thus, high efifcient preservation technologies for aquatic products become particularly important. Superchilling is one of the controlled-temperature preservation technologies for seafood. Aquatic products can be kept in better quality under superchilling conditions. This review introduced the principle and development of superchilling process, mainly focusing on research progresses and technical dififculties of superchilling. The growth mechanism of ice crystals and the feasibility of application of computational lfuid dynamics in analyzing the temperatures variation and ice crystals during superchilling progress were also discussed, which will provide theoretical foundation for its improvement and application.

Issues and Development Opportunities of Aquatic Product Industry in China

China is the largest producer and trader of aquatic products in the world, but does not mean that it belongs to the strongest power group of aquatic production and trade. This paper objectively analyzed the main problems existing in the highspeed development of China＇s aquatic product industry by empirical analysis. For example, the situation of quality and safety of aquatic products is serious now; the basic conditions of aquaculture lag behind the production development; aquatic industry is still in a low level of development and organization; and the quality and safety of aquatic products is the most main problem. This paper also revealed that fish would be the main source of animal-derived food, and the demand of characteristic aquatic products would continuously go up. Aquatic processing has initially formed a standard system. It drew a conclusion that it would be a good opportunity for China＇s aquatic processing industry in the future

Models for Ordering Multiple Products Subject to Multiple Constraints, Quantity and Freight Discounts

One of the most important responsibilities of a supply chain manager is to decide “how much” (or “many”) of inventory items to order and how to transport them. This paper presents four mixed-integer linear programming models to help supply chain managers make these decisions for multiple products subject to multiple constraints when suppliers offer quantity discounts and shippers offer freight discounts. Each model deals with one of the possible combinations of all-units, incremental quantity discounts, all-weight and incremental freight discounts. The models are based on a piecewise linear approximation of the number of orders function. They allow any number of linear constraints and determine if independent or common (fixed) cycle ordering has a lower total cost. Results of computational experiments on an example problem are also presented.

Hunan Yahua Aquatic Product Co., Ltd.

Hunan Yahua Aquatic Product Co., Ltd. is a professional aquatic product processing enterprise, an independence legal person under the listed company - Hunan Yahua Seeds Share Holding Co., Ltd.. Conveniently located at Yiyang City of Hunan Province, the company is by the Dongting Lake, in the north of Shichang Railway, in the east of Changchang High Way and in the

Sensitivity of Planktonic Aquatic Bacteria to Ciprofloxacin

Many anthropogenic compounds, such as antibiotics, are found at trace levels (-1) in aquatic and terrestrial systems. The effect of these compounds on the metabolism and function of microbes are difficult to assess because the assays used, such as the minimum inhibitory concentration (MIC) and the disk diffusion methods, lack the sensitivities to measure bacterial response to these very low levels of antibiotics on bacterial populations. Therefore, we theorized that the [3H] thymidine incorporation into DNA method might be sensitive in determining the effect of DNA inhibiting antibiotics on DNA production in planktonic bacteria in aquatic systems. Utilizing the 3H thymidine method, we measured the effects of ciprofloxacin on DNA production on planktonic bacteria in river and pond waters. Ciprofloxacin significantly (P < 0.02) inhibited river water bacteria at a concentration of 25 μg·L-1 but significant inhibition (P < 0.01) occurred at 1000 μg·L-1in pond water. The very low concentration required to inhibit DNA production in river water bacteria indicates that bacteria are extremely sensitive to antibiotics at very low concentrations. A likely reason for the differences in inhibition between the two waters is due to ciprofloxacin becoming bound, and possibly becoming biologically inactive, in the pond water due to higher dissolved organic carbon content. This work demonstrates that bacteria in some aquatic systems can be significantly impacted by low concentrations of anthropogenic antibiotics finding their way into these systems and that our assumptions as to the concentrations at which antibiotics affect microbes are highly underestimated.

Photosynthesis of Submerged and Surface Leaves of the Dwarf Water Lily(Nymphoides aquatica)Using PAM Fluorometry

Dwarf Water Lilies Nymphoides aquatica(J.F.Gmel)Kuntze have floating and submerged leaves.Some submerged aquatic vascular plants have a form of CAM(Crassulacean Acid Metabolism)called Submerged Aquatic Macrophyte(SAM)metabolism.Blue-diode based PAM technology was used to measure the Photosynthetic Oxygen Evolution Rate(POER:1O_(2)≡4e^(-)).Optimum Irradiance(E_(opt)),maximum POER(POER_(max))and quantum efficiency(α_(0))all vary on a diurnal cycle.The shape of the POER vs.E curves is different in seedling,submerged and surface leaves.Both E_(opt) and POER_(max) are very low in seedling leaves(E_(opt)≈104μmol photon m^(-2) s^(-1),PPFD;POER_(max)≈4.95µmol O_(2) g^(-1) Chl a s^(-1)),intermediate in mature submerged leaves(E_(opt)≈419µmol photon m^(-2) s^(-1) PPFD,POER_(max)≈38.1µmol O_(2) g^(-1) Chl a s^(-1))and very high in surface leaves(E_(opt)≈923µmol photon m^(-2) s^(-1) PPFD,POER_(max)≈76.1µmol O_(2) g^(-1) Chl a s^(-1)).Leaf titratable acid(C4 acid pool)is too small(≈20 to 50 mol H+m^(-3))to support substantial SAM metabolism.Gross daily photosynthesis of surface leaves is≈3.71 g C m^(-2) d^(-1) in full sun and as much as 1.4 gC m^(-2) d^(-1) in shaded submerged leaves.There is midday inhibition of photosynthesis.

芳香中药在动物健康养殖中的研究与应用

多年来,动物生产中滥用抗生素等药物给人类健康带来了严重威胁,着眼于提高动物机体健康水平或将成为未来畜禽水产业可持续发展的方向。芳香中药通常指以挥发性物质为主要有效成分具有芳香气味的中药材及其提取物,具有抗菌、抗炎、增强免疫等作用。近年来,很多研究都在探讨芳香中药作为饲用替抗产品的潜力,文章综述了芳香中药的作用机制及其动物生产中的研究进展,并分析了芳香中药与动物健康养殖的关系及芳香中药当前存在的问题,对其发展前景进行了展望。文章旨在总结芳香中药目前的研究状况,为芳香中药在畜禽、水产健康养殖及饲料工业等方面的研究提供参考意见。

水产品过敏原及其检测技术概述

水产品因鲜美的味道和丰富的营养而深受消费者青睐。水产品属于联合国粮农组织和世界卫生组织认定的过敏食物,其在加工、运输、贮藏过程中有可能受到外来过敏原的污染,由此引起的食品安全问题日益严峻,严重制约了行业的发展。明确水产食品中的过敏原,并利用适当的检测技术进行检测、监控,有利于预防水产食物过敏疾病的发生。本文概述水产食品中的主要过敏原,以及基于基因水平的核酸检测技术、蛋白水平的免疫检测技术及质谱检测技术研究进展,为丰富水产品过敏原及其检测手段提供理论依据。