Rapid detection of pork meat freshness by using L-cysteine-modified gold electrode

In this research, a simple and rapid glucose sensor was developed and applied in the detection of meat glucose. The gold electrode was modified using L-cysteine and nanogold solution, and a polyglutamate–glucose oxidase (GOx) complex was prepared and dropped on the modified electrode; the electrostatic binding between the L-cysteine on the electrode surface and the polyglutamate moiety of the complex resulted in the formation of a GOx-attached electrode. Glucose in meat was detected, and the enzyme electrode showed a quick response. The optimum operating conditions for this sensor were determined as follows: 0.1 M citrate buffer pH 5.0 was found to be suitable for this experiment, and the temperature was kept between 25 and 30 °C which is the suitable range for the GOx activity. A linear relationship was found between 0.1 and 0.9 mM/mL. High pressure liquid chromatography (HPLC) was also used to detect pork meat glucose, and total volatile basic nitrogen (TVBN) production was as well detected as a quality index of pork meat freshness. The results showed that the developed sensor was fast and reliable method for the detection of glucose in meat.     

An electrochemical-based fuel-cell model suitable for electrical engineering automation approach

This paper presents a dynamic electrochemical model for representation, simulation, and evaluation of performance of small size generation systems emphasizing particularly proton exchange membrane fuel-cell (PEMFC) stacks. The results of the model are used to predict the output voltage, efficiency, and power of FCs as a function of the actual load current and of the constructive and operational parameters of the cells. Partial and total load insertion and rejection tests were accomplished to evaluate the dynamic response of the studied models. The results guarantee a better analytical performance of these models with respect to former ones with a consequent reduction in time and costs of projects using FCs as the primary source of energy. Additionally, this electrochemical model was tested for the SR-12 Modular PEM Generator, a stack rated at 500 W, manufactured by Avista Laboratories, for the Ballard Mark V FC and for the BCS 500-W stack.     

Comparison of calibration curve fitting methods in the determination of H2S mass fractions in natural gas by GC-SCD

This paper discusses metrologically the best practice regarding the calibration curves applied to H₂S mass fractions determination in natural gas by gas chromatography with sulfur chemiluminescence detection (GC-SCD). Three calibration curves were constructed by performing GC-SCD analysis of different H₂S gas standard concentrations (from 3 mg kg^?1 up to 500 mg kg^?1). These experimental curves are better fitted by an unweighted quadratic calibration curve considering ANOVA approach compared to ASTM D5504-12. Despite this, the obtained results show that these two different calibration curve approaches (ASTM and ANOVA) lead to comparable results. Hence, there are no significant statistical differences between these two approaches based on the hypothesis test applied. However, the quadratic calibration curve presents measurement uncertainties of H₂S mass fractions much lower than the ASTM approach.     

Trends in breast cancer screening in Missouri from 1987 to 1995, and predictions for the years 2000 and 2010

BACKGROUND: Breast cancer is a major cause of morbidity and mortality in the United States (U.S.) and Missouri. In 1992, 3,915 new breast cancer cases were diagnosed and in 1995, 1,006 deaths from breast cancer were reported in Missouri. Although breast cancer incidence has increased in Missouri in the past 20 years, there are indications that early detection has also increased during the same period. Knowledge about which segments of the population have experienced the greatest increase in mammography screening rates helps in planning and implementation of breast cancer control programs at the state level. OBJECTIVES: Examine the prevalence and trends of lifetime mammography and 2-year mammography compliance in Missouri by age, race, and education from 1987 to 1995 and make predictions for the years 2000 and 2010. METHODS: We used data from the Missouri Behavioral Risk Factor Surveillance System (BRFSS), 1987 to 1995, to estimate the prevalence of ever having had a mammogram and compliance with mammography screening guidelines within two years by race, age, and education status among Missouri women over age 18. Using linear models, we regressed breast cancer screening prevalence estimates on time to obtain trends and predictions. RESULTS: Overall, African-American women were more likely to have had a lifetime mammogram than white women. However, we found a steady increase in the prevalence of ever having had a mammogram for all groups of women defined by age and education status, except among African Americans. Increase in the prevalence of ever having had a mammogram was much higher in women age 50 and older and slightly higher among women with a high school education or less. The average prevalence of 2-year mammography screening compliance was about 60% for all groups, a rate which did not significantly change between 1987 and 1995. By the year 2000, white women will have mammography rates equal to or higher than African-American women, and the majority of all women age 50 and older (98.3% to 100%) will have had a lifetime mammogram. CONCLUSION: Missouri target populations are predicted to attain Year 2000 National Health Objectives concerning lifetime mammography. Current efforts should be continued in order to maintain levels of mammography, particularly among African-American women.     

Variability and molecular typing of Streptococcus thermophilus strains displaying different proteolytic and acidifying properties

Proteolytic and acidifying properties of Streptococcus thermophilus strains isolated from yoghurt or cheeses were evaluated. Among 30 strains tested, 12 exhibited cell envelope-associated proteinase activity (PrtS⁺), three displayed a slight PrtS activity (PrtS^+/?) and 15 were PrtS^?, despite the presence of the corresponding gene (prtS) in eight of them. Sequencing of the prtS gene in four PrtS^? and one PrtS⁺ strains revealed that the absence of PrtS activity in the PrtS^? strain probably results from an alteration of the prtS regulation. The strains displaying the highest acidifying capacities were all PrtS⁺. All but one PrtS⁺ strains were phylogenetically close, as shown by the sequencing of their rDNA internal transcribed spacer (ITS) 16S-23S. More specifically, the high proteolytic and acidifying capacities are associated with the presence of a type II-ITS.     

Field-effect transistor with diphthalocyanine thin film

A field effect transistor has been fabricated with organic semiconductors: scandium diphthalocyanine and nickel phthalocyanine. The electrical characteristics are studied in air atmosphere. The influence of the diphthalocyanine film thickness has been detected     

Microbiological,physical and chemical characteristics of freshwater prawns (Macrobrachium rosenbergii) in modified‐atmosphere packaging

This study evaluated the influence of packaging atmosphere (air versus 50% N₂/50% CO₂) on microbiological (mesophiles, psychrotrophs), physical (gas measurement) and chemical (pH, total volatile basic nitrogen [TVB‐N], NH₃, H₂S and biogenic amines) parameters in freshwater prawns during storage at 0 ± 1 °C for 240 h. To select the most appropriate packaging, 21 batches of each treatment were analysed. Both the packaging permeability and the combination of gases affected the shelf life, but the modified‐atmosphere packaging (MAP) was more efficient than air packaging, increasing the shelf life by 40 h. The parameters of pH and TVB‐N showed no statistical difference between the two atmosphere conditions all along the storage period. The biogenic amine agmatine showed potential for use as a quality indicator due to the increased concentration during storage. In further studies, this amine can be applied as an indicator for public health issue.