The objective of this paper was to optimize an electrophoretic methodology (Tricine-SDS-PAGE) to monitor the degree of caseins hydrolysis during the maturation time of artisanal cheese. A cheaper and easier method was...The objective of this paper was to optimize an electrophoretic methodology (Tricine-SDS-PAGE) to monitor the degree of caseins hydrolysis during the maturation time of artisanal cheese. A cheaper and easier method was obtained using small samples and micro-quantities of reagents. Simultaneous detection of proteins and peptides (100 kDa to 1 kDa) in the same gel was another advantage of the method. Initially, protein extraction was performed with 2 mg of lyophilized cheese dissolved in 1.0 mL of sample electrophoretic buffer for 1 h under stirring. After that, the Eppendorf tubes of the samples were kept at -4 °C for 4 h with additional centrifugation at 5,433 ×g for 2 min. This defatting process using centrifugation/refrigeration promoted a good separation of proteins and peptides from the fat layer. After this step, 30 L of the supernatant of the protein extracts was applied to the electrophoresis gel. The results revealed a clear image of protein and peptides in the polyacrylamide gels and allowed an excellent response of the distribution of casein bands (α, β and κ) and the exposure peptide in cheese. The utilization of artisanal cheese as a pilot study of molecular protein analysis could be helpful for further correlation of the fingerprint of protein-peptide profile with taste quality.展开更多
Limitations exist in applying discounted cash flow and analogy sales methods to evaluate mining titles. In order to find a more appropriate way of evaluating mining titles, the Black-Scholes model is discussed in this...Limitations exist in applying discounted cash flow and analogy sales methods to evaluate mining titles. In order to find a more appropriate way of evaluating mining titles, the Black-Scholes model is discussed in this paper. The authors pay particular attention to the determination of the time to maturity of the option on the basis of characteristics of the mining industry, pointing out that a reasonable time to maturity of the option should be the remaining time after deducting the essential time, needed by exploitation of the mineral resources within the mining property, from the life of the mining title. Several conclusions, related to the exercise of mineral resource management, are drawn from a case study analysis; extending the life of a mining title within a certain range could increase the revenue to the seller of the mining title. Application of the Black-Scholes model to evaluate mining titles would encourage an expansion of the scale of production.展开更多
This paper formulates a robust stage-structured SI eco-epidemiological model with periodic constant pulse releasing of infectious pests with pathogens. The authors show that the conditions for global attractivity of t...This paper formulates a robust stage-structured SI eco-epidemiological model with periodic constant pulse releasing of infectious pests with pathogens. The authors show that the conditions for global attractivity of the ＇pest-eradication＇ periodic solution and permanence of the system depend on time delay, hence, the authors call it ＂profitless＂. Further, the authors present a pest management strategy in which the pest population is kept under the economic threshold level （ETL） when the pest population is uniformly persistent. By numerical analysis, the authors also show that constant maturation time delay for the susceptible pests and pulse releasing of the infectious pests can bring obvious effects on the dynamics of system.展开更多
文摘The objective of this paper was to optimize an electrophoretic methodology (Tricine-SDS-PAGE) to monitor the degree of caseins hydrolysis during the maturation time of artisanal cheese. A cheaper and easier method was obtained using small samples and micro-quantities of reagents. Simultaneous detection of proteins and peptides (100 kDa to 1 kDa) in the same gel was another advantage of the method. Initially, protein extraction was performed with 2 mg of lyophilized cheese dissolved in 1.0 mL of sample electrophoretic buffer for 1 h under stirring. After that, the Eppendorf tubes of the samples were kept at -4 °C for 4 h with additional centrifugation at 5,433 ×g for 2 min. This defatting process using centrifugation/refrigeration promoted a good separation of proteins and peptides from the fat layer. After this step, 30 L of the supernatant of the protein extracts was applied to the electrophoresis gel. The results revealed a clear image of protein and peptides in the polyacrylamide gels and allowed an excellent response of the distribution of casein bands (α, β and κ) and the exposure peptide in cheese. The utilization of artisanal cheese as a pilot study of molecular protein analysis could be helpful for further correlation of the fingerprint of protein-peptide profile with taste quality.
基金Project 50074031 supported by National Natural Science Foundation of China
文摘Limitations exist in applying discounted cash flow and analogy sales methods to evaluate mining titles. In order to find a more appropriate way of evaluating mining titles, the Black-Scholes model is discussed in this paper. The authors pay particular attention to the determination of the time to maturity of the option on the basis of characteristics of the mining industry, pointing out that a reasonable time to maturity of the option should be the remaining time after deducting the essential time, needed by exploitation of the mineral resources within the mining property, from the life of the mining title. Several conclusions, related to the exercise of mineral resource management, are drawn from a case study analysis; extending the life of a mining title within a certain range could increase the revenue to the seller of the mining title. Application of the Black-Scholes model to evaluate mining titles would encourage an expansion of the scale of production.
基金the National Natural Science Foundation of China under Grant No.10471117,10771179the Natural Science and Development Foundation of Shandong University of Science and Technology under Grant No.05g016
文摘This paper formulates a robust stage-structured SI eco-epidemiological model with periodic constant pulse releasing of infectious pests with pathogens. The authors show that the conditions for global attractivity of the ＇pest-eradication＇ periodic solution and permanence of the system depend on time delay, hence, the authors call it ＂profitless＂. Further, the authors present a pest management strategy in which the pest population is kept under the economic threshold level （ETL） when the pest population is uniformly persistent. By numerical analysis, the authors also show that constant maturation time delay for the susceptible pests and pulse releasing of the infectious pests can bring obvious effects on the dynamics of system.
