2023年全國碩士研究生考試考研英語一試題真題(含答案詳解+作文范文)_第1頁
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1、Food is the only source of life and it offers invaluable advantages: growth and health promotion, energy, and disease prevention; hence, life will not exist without food.Peoplelike enjoying sharing meal-gathering togethe

2、r and like to taste different kinds of traditionalcuisines; yet they also demand for consumption of quality and safe food.Principally, food,generally reconsidered as safe (GRAS), should be strictly produced from sanitati

3、ons, good manufacturing practices, good handling practices, and good agriculture practices toconform with food safety system guideline in order to prevent the contamination orrecontamination, especially microbial pathoge

4、ns and toxic chemicals, because these materials cannot be visually detected.Food contaminations resulting to food poisonings areobviously very serious issues to public health, living welfare, and socio-economicdevelopmen

5、t; therefore, they need to be tightly controlled (prevention, reduction, and elimination) before serving on the tables or markets.To tackle such these difficultproblems is a main task and huge challenge for regulatory au

6、thorities, public healthagencies, and food industries in order to ensure the quality and safe-to-eat food.
  Because of visually impossible detection of food hazards, numerous sophisticallyefficient analytical methods

7、 have been successfully developed in order to meet the growing demands for food safety and quality control and supervision.Although food toxicity mostly comes from pathogenic microbes, toxic chemicals; such as pesticide

8、residues,illegal food additives, drug residues; are also a major threat to the life and public health;therefore, there is an increasingly considerable interest in developing new selective and sensitive method for extract

9、ing, isolating, and enriching contaminated components from complex food matrices.One of the promising methods that have been innovated so far isa molecularly imprinting technique, which has drawn a great attraction world

10、wide in thefield of chemical separation science.The exploitation of this technique could produce aproduct of molecularly imprinted polymers (MIPs); which are very robustness, long-termstability, reliability, cost-efficie

11、ncy, and selectivity; creating MIPs to gain more popularityin chemical separation and analysis.
  In this dissertation, we would like to introduce "an analytical method" using MIPs-based materials as a solid phase ext

12、raction for selective recognition of given chemical molecules from the food matrices before high performance liquid chromato graphicde termination.The technique of MIPs synthesis is based on a traditional method, which b

13、ulk MIPs need to be ground, sieved, and Soxhlet washed prior to applying them as amolecularly-imprinted solid-phase extraction (MISPE) for sample clean-up and enrichment.The main functional monomer and cross-linker we us

14、e in MIPs polymerization is β(beta)-cyclodextrin, a 7-membered sugar ring molecule and ethylene glycol dimethacrylate(EGDMA), respectively.Our introduced method of MIPs polymerization is simple and inexpensive; moreover,

15、 the volume of organic solvent involved in the synthesis of MIPsand the rest of experimental process requires minimally, which is in parallel with environmentally-friendly way.Our findings are as follows.
  (1)In chap

16、ter two, we prepared a series of di (2-ethylhexyl) phthalate (DEHP)imprinted polymers by using the single use of ailyl bromine-β-cyclodextrin (allyl-β-CD)and the combined use of allyl-β-CD and methacrylic acid (MAA), all

17、yl-β-CD and methylmethacrylate (MMA), allyl-β-CD and acrylonitrile (AN), and allyl-β-CD and acrylamide(AA) as the binary functional monomers.The results proved that the binary function almonomers, except for AA monomer,

18、are superior to a single monomer; their average bound substrate from binary monomers was ~110 μmol g-1, where as a single was ~90μmol g-1 in binding specificity.Finally, M-MAA, M-MMA and M-AN were chosen to runthrough mo

19、lecularly imprinted solid-phase extraction (MISPE) to analyze the spiked infantformula of DEHP.For M-AN, the recovery ranged from 93.59-97.98% with relativestandard deviations (RSD ≤ 3.21%).
  (2)In chapter three, we

20、synthesized three kinds of clenbuterol-imprinted polymers bythe combined use of ally-β-cyclodextrin (ally-β-CD) and methacrylic acid (MAA), allyl-β-CD and acrylonitrile (AN), and allyl-β-CD and methyl methacrylate (MMA)

21、as the binaryfunctional monomers.Based upon the results, M-MAA polymers generally proved to be anexcellent selective extraction compared to its references: AN-linked allyl-β-CD MIPs (M-AN) and MMA-linked allyl-β-CD MIPs

22、(M-MMA).M-MAA polymers were eventuallychosen to run through a molecularly imprinted solid-phase extraction (MI-SPE) microcolumn to enrich CLEN residues spiked in pork livers.A high recovery was achievedranging from 91.03

23、-96.76% with relative standard deviation (RSD ≤ 4.45%).
  (3)In chapter four, we exploited binary functional monomers, allyl-β-cyclodextrin(allyl-β-CD) and methacrylic acid (MAA) or allyl-β-CD and acrylonitrile (AN),

24、in afabrication of molecularly imprinted polymers (MIPs) for selective recognition and largeenrichment of pirimicarb pesticide from aqueous media.According to the results, the effectof binding capacity of MAA-linked ally

25、l-β-CD MIPs (M-MAA) demonstrated higherefficiency than that of AN-linked allyl-β-CD MIPs (M-AN) when tested in bindingspecificity.Finally, M-MAA was chosen to run through molecularly imprinted solid-phaseextraction (MISP

26、E) to analyze the spiked fresh leafy vegetables of pirimicarb.The presentproposed technique is a promising tool for the preparation of the receptors which couldrecognize pirimicarb pesticide in aqueous media.
  Accord

27、ing to the aforementioned results, we found that our synthesized MIPs could beused for a sample clean-up and pre-concentration of target analytes of interest in foodmatrices.Our MIPs showed good stability, good selectivi

28、ty, and high efficient adsorptioncapacity towards the target molecules; therefore, they could be applied to real food samplesas an integral part of analytical method for food quality and safety control and supervision.

29、r>  There are a variety of applications of MIPs such as off-line or on-line solid phaseextraction (SPE), chemical and bio-sensors, catalysis, and drug delivery because MIPs, asynthetically potential artificial receptor-l

30、ike binding sites with a "memory" for shape andfunctional group positions of the target molecule, possess a competent ability for selectivespecificity and recognition for target or unwanted chemical molecules.Among vario

31、usMIPs applications, the most commonly used is an off-line solid phase extractionapplication due to its simplicity.Utilizations of MIPs-based materials have been applied toa wide range of chemicals, including food contam

32、inants, pesticides, environmentalpollutants, preservatives, and antibiotic drug residues for sample clean-up and preconcentration, detection, and quantification.
  All in all, due to various functionalities of MIPs su

33、ch as solid phase extraction (SPE),chemical and bio-sensors, catalysis, and drug delivery, molecular imprinting technique hasdrawn a huge attraction from a wide range of fields, including food safety, chemistry,biology,

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