Liu Jun-hong

Bio: Liu Jun-hong is an academic researcher from Qingdao University of Science and Technology. The author has contributed to research in topics: Enantioselective synthesis & Food spoilage. The author has an hindex of 3, co-authored 7 publications receiving 56 citations.

Development of transdermal drug delivery system

Abstract: Historically,developments in transdermal drug delivery have been incremental,The transdermal drug delivery(TDD) mainly depend on skin barrier its molecular size and hydrophilic/hydrophobic properties.The efficient improvement of TDD(especially biomacromolecular) can be made by embedding the drug by some physical and chemical means,and simultaneously using vehicle.Fundamentally,improvements in transdermal delivery will remain incremental until there is wider acceptance of this route of administration within the pharmaceutical industry.Only then will the transdermal revolution live up to its true potential.

Hydroxynitrile lyases: At the interface of biology and chemistry

Abstract: Hydroxynitrile lyases are the versatile group of enzymes,which play a significant defensive role in plant system against microbial attack. In chemical industries, hydroxynitrile lyase is used as an important industrial biocatalyst for the synthesis of chiral cyanohydrins by exploiting the reversible enzymatic reaction. Cyanohydrins are biologically active compounds used in synthesis of β-amino alcohols, a-hydroxy ketones anda-hydroxy acids, which have importance as fine chemicals, Pharmaceuticals and agrochemicals. Protein engineering and site directed mutagenesis have been used to change the active site and alter the substrate specificity of various ydroxynitrile lyases. Many recombinant hydroxynitrile lyases have been expressed in Escherichia coli, Saccharomyces cerevisiae and Pichia pastoris.

Fish Spoilage Bacteria-Problems and Solution

Abstract: Microorganisms are the major cause of spoilage of most seafood products。However,only a few species of themicrobial community,the specific spoilage organisms(SSOs) result in seafood spoilage.Combining microbial ecology,moleculartechniques,analytical chemistry and mathematical modelling might allow us to determine and extend the shelf life of seafoodproducts.

Solid phase extraction of food contaminants using molecular imprinted polymers

Abstract: Food contamination from natural or anthropogenic sources poses severe risks to human healthIt is now largely accepted that continuous exposure to low doses of toxic chemicals can be related to several chronic diseases,including some type of cancer and serious hormonal dysfunctionsContemporary analytical methods have the sensitivity required for contamination detection and quantification,but direct application of these methods on food samples can be rarely performedCurrent sample pre-treatment methods,mostly based on the solid phase extraction technique,are very fast and inexpensive but show a lack of selectivity,while methods based on immunoaffinity extraction are very selective but expensiveRecent years have seen a significant increase of the "molecularly imprinted solid phase extraction"(MISPE)technique in the food contaminant analysisIn this review,several applications of MISPE in food contamination analysis were discussed,with particular emphasis on the extraction of pesticides,drugs residua,mycotoxins and environmental contaminants

Progress in Biocatalytic Conversion of Epoxides

Abstract: Epoxides were attractive intermediates for producing chiral compounds.Important biocatalytic reactions involving epoxides included epoxide hydrolase mediated kinetic resolution,leading to the formation of diols and enantiopure remaining substrates,and enantioconvergent enzymatic hydrolysis,which given high yields of a single enantiomer from racemic mixtures.Epoxides could also be converted by non-hydrolytic enantioselective ring opening,using alternative anionic nucleophiles;these reactions could be catalyzed by haloalcohol dehalogenases.The differences in scope of these enzymatic conversions were related to their different catalytic mechanisms,which involved,respectively, covalent catalysis with an aspartate carboxylate as the nucleophile and non-covalent catalysis with a tyrosine that acted as a general acidbase.The emerging new possibility for enantioselective biocatalytic conversion of epoxides suggested that their importance in green chemistry would grow.

Development of a Microbial Model for the Combined Effect of Temperature and pH on Spoilage of Ground Meat, and Validation of the Model under Dynamic Temperature Conditions

Abstract: The changes in microbial flora and sensory characteristics of fresh ground meat (beef and pork) with pH values ranging from 5.34 to 6.13 were monitored at different isothermal storage temperatures (0 to 20 degrees C) under aerobic conditions. At all conditions tested, pseudomonads were the predominant bacteria, followed by Brochothrix thermosphacta, while the other members of the microbial association (e.g., lactic acid bacteria and Enterobacteriaceae) remained at lower levels. The results from microbiological and sensory analysis showed that changes in pseudomonad populations followed closely sensory changes during storage and could be used as a good index for spoilage of aerobically stored ground meat. The kinetic parameters (maximum specific growth rate [mu(max)] and the duration of lag phase [lambda]) of the spoilage bacteria were modeled by using a modified Arrhenius equation for the combined effect of temperature and pH. Meat pH affected growth of all spoilage bacteria except that of lactic acid bacteria. The "adaptation work," characterized by the product of mu(max) and lambda(mu(max) x lambda) was found to be unaffected by temperature for all tested bacteria but was affected by pH for pseudomonads and B. thermosphacta. For the latter bacteria, a negative linear correlation between ln(mu(max) x lambda) and meat pH was observed. The developed models were further validated under dynamic temperature conditions using different fluctuating temperatures. Graphical comparison between predicted and observed growth and the examination of the relative errors of predictions showed that the model predicted satisfactorily growth under dynamic conditions. Predicted shelf life based on pseudomonads growth was slightly shorter than shelf life observed by sensory analysis with a mean difference of 13.1%. The present study provides a "ready-to-use," well-validated model for predicting spoilage of aerobically stored ground meat. The use of the model by the meat industry can lead to effective management systems for the optimization of meat quality.

The BioCassava Plus Program: Biofortification of Cassava forSub-Saharan Africa

Abstract: More than 250 million Africans rely on the starchy root crop cassava (Manihot esculenta) as their staple source of calories. A typical cassava- based diet, however, provides less than 30% of the minimum daily requirement for protein and only 10%–20% of that for iron, zinc, and vitamin A. The BioCassava Plus (BC+) program has employed modern biotechnologies intended to improve the health of Africans through the development and delivery of genetically engineered cassava with increased nutrient (zinc, iron, protein, and vitamin A) levels. Additional traits addressed by BioCassava Plus include increased shelf life, reductions in toxic cyanogenic glycosides to safe levels, and resistance to viral disease.

Factors affecting electrode-gel-skin interface impedance in electrical impedance tomography

Abstract: The magnitude, mismatch and temporal variations of the electrode-gel-skin interface impedance can cause problems in electrical impedance tomography (EIT) measurement. It is shown that at the high frequencies generally encountered in EIT the capacitive properties of the electrode interface, and especially those of the skin, are of primary importance. A wide range of techniques are reviewed that could possibly be used to minimise these problems. These techniques include the use of skin preparation, penetration enhancers, temperature and electrical impulses. Although several of these techniques appear very attractive, they are not without serious potential drawbacks. A combination of some of these techniques may well hold the key to success.