Periodic Solution of a Nonautonomous Diffusive Food Chain System of Three Species with Time Delays

By using the continuation theorem of coincidence degree theory, the existence of a positive periodic solution for a nonautonomous diffusive food chain system of three species.is established, where ri(t), aii(t) (i = 1.2,3,4), Di(t) (i = 1,2), a12(t), a21(t), a23(t) and a32(t) are all positive periodic continuous functions with period w > 0, Ti(i = 1,2) are positive constants.

A Food Traceability System Based on Blockchain and Radio Frequency Identification Technologies

The frequent occurrence of food safety accidents at the global level has triggered consumer sensitivity. Establishing a food traceability system can effectively guarantee food safety and increase consumer confidence and satisfaction. Existing food traceability systems often ignore environmental factors that affect food quality at all stages of the supply chain, and the authenticity of the information obtained through traceability is difficult to guarantee. In this study, a food supply chain traceability model was established based on blockchain and radio frequency identification (RFID) technologies. The model focused on the traceability of environmental data during the various stages of the food supply chain and combined a centralized database and blockchain for data storage. The lot identification data of the various supply chain stages were stored in a centralized database, while the environmental data were stored in a blockchain. Thereby, the authenticity and accuracy of the traceability data were ensured. The blockchain part of the model has been simulated in the Ethereum test environment, and the experiment has achieved traceability of temperature data.

Biotransfer of heavy metals along a soil-plant-insect-chicken food chain:Field study

The accumulation and transfer of Pb,Zn,Cu,and Cd along a soil-plant-insect-chicken food chain at contaminated sites were investigated.The study site nearing the Pb/Zn mine had been contaminated by heavy metals severely.Cadmium and Pb concentrations steadily declined with increasing trophic level（p 〈 0.01）,but concentrations of Zn and Cu slightly increased from plant to insect larva（p 〉 0.05）.The concentrations of heavy metals were the highest in chicken muscle,with lower values in liver and blood.The bioaccumulation of Pb was observed in chicken livers.The eliminations of Pb,Zn,Cu,and Cd via insect and chicken feces avoid metal bioaccumulation in insect and chicken body.These results suggest that the accumulation of heavy metals in specific animal organ of tissues could not be neglected,although transfer of metals to chicken from plant and insect was limited.

Transfer of Paralytic Shellfish Toxins via Marine Food Chains:A Simulated Experiment

Objective To study the transfer of paralytic shellfish toxins （PST） using four simulated marine food chains： dinoflagellate Alexandrium tamarense→Artemia Artemia salina→Mysid shrimp Neomysis awatschensis; A. tamarense→N. awatschensis; A. tamarense→A, salina→Perch Lateolabrax japonicus; and A. tamarense→L, japonicus. Methods The ingestion of A. tamarense, a producer of PST, by L. japonicus, N. awatschensis, and A. salina was first confirmed by microscopic observation of A. tamarense cells in the intestine samples of the three different organisms, and by the analysis of Chl.a levels in the samples. Toxin accumulation in L. japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly through the vector of A. salina was then studied, The toxicity of samples was measured using the AOAC mouse bioassay method, and the toxin content and profile of A. tamarense were analyzed by the HPLC method. Results Both A. salina and N. awatschensis could ingest A. tamarense cells. However, the ingestion capability of A. salina exceeded that of N. awatschensis. After the exposure to the culture of A. tamarense （2 000 cells·mL^-1） for 70 minutes, the content of Chl.a in A. salina and N. awatschensis reached 0.87 and 0.024 μg.mg^-1, respectively. Besides, A. tamarense cells existed in the intestines of L. japonicus, N. awatschensis and A. salina by microscopic observation. Therefore, the three organisms could ingest A. tamarense cells directly. A. salina could accumulate high content of PST, and the toxicity of A. salina in samples collected on days 1, 4, and 5 of the experiment was 2.18, 2.6, and 2.1 MU.g^-1, respectively. All extracts from the samples could lead to death of tested mice within 7 minutes, and the toxin content in anemia sample collected on the 1st day was estimated to be 1.65×10 ^5 μg STX equal/individual. Toxin accumulation in L japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly from the vector ofA. salina was also studied. The mice injected with extracts from L japonicus and N. awatschensis samples that accumulated PST either directly or indirectly showed PST intoxication symptoms, indicating that low levels of PST existed in these samples. Conclusion Paralytic shellfish toxins can be transferred to L. japonicus, N. awatschensis, and A. salina from A. tamarense directly or indirectly via the food chains.

Poverty reduction through the development of inclusive food value chains

Propelled by urbanization,rising incomes,and changing diets,food markets have been expanding in Africa and South Asia,creating the vast potential for job and income opportunities along food supply chains and,hence,for poverty reduction.The novel coronavirus(COVID-19)that spread to a pandemic in early 2020 provokes enormous setbacks to this expansion.This,however,should provide lessons regarding the importance of resilient and inclusive food systems.Emergency responses to COVID-19 should consider interventions towards that end and leverage the opportunities provided by food markets growth as economies recover from the present economic recession.This paper assesses options of how this could be done by facilitating the better functioning and interconnectedness of the many small and medium-sized enterprises that are proliferating along the"hidden middle"of food value chains in storage,logistics,transportation,and wholesale and retail distribution.It also explores how policies can help smallholder farmers connect to this"hidden middle"in more gainful ways and help them climb out of poverty as well.

Optimal harvesting for an age-dependent n-dimensional food chain model

This paper is concerned with optimal harvesting policy for an age-dependent n-dimensional food chain model. The existence and uniqueness of non-negative solution of the system are proved using the fixed point theorem. By Mazur＇s theorem, the existence of optimal control strategy is demonstrated and optimality conditions derived by means of normal cone.

A dynamic food-chain model and program for predicting the consequences of nuclear accident

A dynamic food chain model and program, DYFOM 95, for predicting the radiological consequences of nuclear accident has been developed, which is not only suitable to the West food chain but also to Chinese food chain. The following processes, caused by accident release which will make an impact on radionuclide concentration in the edible parts of vegetable were considered: dry and wet deposition interception and initial retention, translocation, percolation, root uptake and tillage. Activity intake rate of animals, effects of processing and activity intake of human through ingestion pathway ware also considered in calculations. The effects of leaf area index LAI of vegetable were considered in dry deposition model. A method for calculating the contribution of rain with different period and different intensity to total wet deposition was established. The program contains 1 main code and 5 sub codes to calculate dry and wet deposition on surface of vegetable and soil, translocation of nuclides in vegetable, nuclide concentration in the edible parts of vegetable and in animal products and activity intake of human and so on.

Impact of COVID-19 Epidemic on the International Food Supply Chain and Countermeasures of Shandong Province

The COVID-19 epidemic has exerted an impact on the global food supply chain,and also has contributed to the tendency of food hoarding and short supply;strong food demand has led to a rapid rise in international food prices,which has put enormous pressure on China's food import,and domestic food price showed a rise trend accordingly.In order to ensure sufficient and stable supply of China's food market,it is necessary to adhere to the food security strategy of"food self-sufficiency"for a long term.In the spring agricultural production,Shandong Province has taken effective measures to stabilize food production and achieved good results.It has not been greatly affected by the COVID-19 epidemic;however,under the continuous spread of foreign epidemics,we must adhere to the dual hard core operation of epidemic prevention and production,and explore the establishment of technical specifications for agricultural production under normal conditions for epidemic prevention and control to ensure the food security.

Safety reliability optimal allocation of food cold chain

This paper applied the safety reliability of food cold chain logistics to establish reliability allocation model for cold chain systems, designed optimization algorithms, and made a case analysis. By applying system reliability allocation principle, this article firstly built safety reliability allocation model of food cold chain logistics system without cost constraint based on the safety reliability model of food cold chain logistics system, and then it set up optimal decision- making model of food cold chain logistics system with cost constraint using the functional relationship between the time, temperature of cold chain logistics and logistics costs. Next, according to the characteristics of the model, a heuristic algorithm was proposed to allocate safety reliability of the system to each cold chain unit so as to achieve the goal of operatingcosts optimization subject to assurance ofoverall safety reliability of the cold chain system. Taking the safety impact factor of food cold chain unit as a weight, the article also deduced the equation of reallocation of safety reliability of food cold chain system. In the end, these models were used to optimize the allocation of safety reliability in an example of Sushi cold chain process. It provided a new thought and method to optimally plan the unit safety of food cold chain system as well as reduce the cost of food cold chain.

Deterministic and Stochastic Fractional-Order Hastings-Powell Food Chain Model

In this paper,a deterministic and stochastic fractional-order model of the tri-trophic food chain model incorporating harvesting is proposed and analysed.The interaction between prey,middle predator and top predator population is investigated.In order to clarify the characteristics of the proposed model,the analysis of existence,uniqueness,non-negativity and boundedness of the solutions of the proposed model are examined.Some sufficient conditions that ensure the local and global stability of equilibrium points are obtained.By using stability analysis of the fractional-order system,it is proved that if the basic reproduction number R_(0)<1,the predator free equilibrium point E_(1) is globally asymptotically stable.The occurrence of local bifurcation near the equilibrium points is investigated with the help of Sotomayor’s theorem.Some numerical examples are given to illustrate the theoretical findings.The impact of harvesting on prey and themiddle predator is studied.We conclude that harvesting parameters can control the dynamics of the middle predator.A numerical approximation method is developed for the proposed stochastic fractional-order model.

The Risk of <i>Fusarium</i>and Their Mycotoxins in the Food Chain

Fusarium sp. and mycotoxins of these species pose a major risk to consumer health, agriculture and the food industry. This paper is a worldwide bibliographic study on impact of Fusarium and mycotoxins on the food chain. The factors influencing the development of fungi Fusarium sp., the formation of mycotoxins and their microbiological risk on the food chain must be considered as a whole. For cereals and oilseeds before and after harvest, fungal infections and mycotoxin contamination present serious problems worldwide. This paper is an overview of the factors that include the microbiological risk and impact of Fusarium in the food chain mentioned in national and international studies. The methods and results obtained in this direction internationally are mentioned, such as: infrared spectroscopy, Raman spectrometry and hyperspectral imaging. Also, in review are presented solutions to reduce this impact on the food chain.

Slackening of Food Supply Chain during COVID-19 and Affecting Livelihood - A Global Concern

The outbreak of COVID-19 has brought about another age on world as the human civilization is restricted in many aspects of everyday lives.There is no exception in the sector of food production and the supply chain of food.Due to constraints on demand,shutting of food production facilities,financial limitations,enterprise operations and delivery of different food items have been interrupted in the food supply chain.Every nation must comprehend the importance of the situation according to the spreading scenario of the ongoing pandemic.The probability of transmission via the food sector is regarded inconsequential,and the public authorities do not believe it necessary to follow COVID into workplaces.The unfavourable effects on the climate,the food framework and the people of the foodstuffs network are evident.An installation for the food supply chain should focus on amenities such as maintaining the safety and health of employees and changing working circumstances.This paper aims at discussing the effects of COVID-19 on the socio-economic status of human being including the negative impacts on the agriculture and food supply chain.

构建粮食产业链供应链一体化体系的研究

全球经济衰退和贸易供应链中断相互叠加加剧了世界粮食安全风险,尽管我国粮食安全形势总体看好,但粮食安全仍不能忽视,需要树立新时代的粮食安全战略,构建与新发展格局相适应的粮食安全观,针对我国粮食安全的主要风险,从高效推动粮食全链发展、积极谋划粮食产业链供应链安全、加大粮食产业高质量发展力度等3个方面提出有针对性地构建粮食产业链供应链一体化体系政策建议,从而确保中国人的饭碗牢牢端在自己手中。

我国冷链食品追溯体系发展现状分析与建议

食品安全追溯体系作为食品安全治理体系的重要组成部分,在传递食品安全信息、缓解食品安全市场信息不对称和增强消费者信心方面起到了重要作用。我国冷链食品追溯体系已初步建立和实施,但在标准体系、追溯能力及追溯技术等方面存在着一些问题。从冷链食品追溯相关政策、标准等方面梳理了我国冷链食品追溯体系现状、存在的问题及面临的挑战,结合我国实际情况提出相应的建议,为我国冷链食品追溯体系建设及监管提供参考依据,以促进我国冷链食品追溯体系的进一步发展和完善。

大食物系统构建中的水产养殖产业链:韧性挑战及提升对策

作为大食物系统的重要组成部分,水产品为国人提供了超过三分之一的动物蛋白,目前我国水产品总产量已经超过猪牛羊肉总产量之和。由于国内水产品主要来源于水产养殖业,且水产养殖业受国内外市场环境变化及自然条件等各种因素影响较大,因此,水产养殖业产业链韧性将深刻影响着我国水产品供给保障安全。本文基于国家统计局数据和调研数据,分析发现我国水产养殖产业链韧性面临抵抗风险能力弱、受冲击后恢复力不够、产业转型力不强等主要挑战。基于此,从加强科技研发与集成、完善渔业保险制度、打造“一条鱼产业链”、加强质量监管、完善资源管理政策等方面提出加强水产养殖产业链韧性的建议。

一类基于等级结构的n维食物链系统最优收获

考虑一类具年龄等级结构的n维食物链种群系统的最优收获问题,首先利用压缩映射定理,研究系统解的适定性;其次构造极值化序列和运用相关的紧性定理证明控制问题最优解的存在性;最后通过构造共轭系统和利用法锥的概念刻画,得出最优收获问题最优解的一阶必要条件.

减少蔬菜全产业链损失与浪费助力食物系统可持续发展

蔬菜的损失与浪费不仅造成了巨大的经济损失,同时对环境也造成了诸多负面影响。为了减少蔬菜全产业链的损失与浪费,助力食物系统可持续发展,对蔬菜的生产、产后处理、贮存、加工、流通、消费等环节的损失与浪费情况进行梳理,总结了全产业链损失和浪费率高、产后处理环节损失严重、减损潜力巨大等蔬菜损失与浪费的特征,分析了自然灾害、相关基础设施不足、供需信息不对称、非标准化操作、消费者偏好、不合理的消费行为等造成蔬菜损失与浪费的主要成因,阐述了蔬菜损失与浪费对资源和环境的影响,在梳理目前我国减少食物损失与浪费所采用的主要举措的基础上,提出了促进全产业链可持续发展的管理策略,包括多方合力制定减少食物减损行动方案、强化监管推进全链条减损标准建设、总结试点经验形成示范推广、加强教育引导文明健康消费理念等。

三个种群Beddington-DeAngelis食物链系统的持久性和稳定性研究

使用比较定理、微分中值定理和不动点定理,分析一类带有食饵庇护和多层干扰的Beddington-DeAngelis食物链系统的持久性和概周期解问题.在持久性的基础上,构造合适的Lyapunov函数,获得该Beddington-DeAngelis食物链系统存在一致渐近稳定概周期解的充分条件.最后,给出一个例子的数值模拟验证结果的有效性.

基于区块链技术的食品可追溯供应链系统研究

建立食品可追溯供应链是解决食品安全问题的有效途径。由于传统的食品可追溯系统的运营成本高,导致一般企业不愿意参与。另外数据容易被篡改,以致消费者不愿接受转移到食品上的追溯系统应用成本造成的溢价。由此为提高追溯系统数据可靠度,需要在系统中融入天然具有不可篡改特点的区块链技术。文章从区块链技术与食品供应链可追溯系统的兼容性出发,理论分析出区块链技术的引入将降低食品供应链的交易成本、质量成本、时间成本、作业成本以及追溯的附加成本。通过对比区块链技术应用前后成本变化,探索基于区块链的食品供应链可追溯系统的成本控制机制,以促进食品供应链可追溯系统的发展。