The promoting effect of alkali nitrates molten salt on the CO 2 capture capacity of a commercial MgO was investigated in detail. In particular, the ratio of Li/Na/K nitrates and the loading of the molten salt mixture on the MgO particles were optimized, and the influence of calcination and adsorption temperatures was evaluated. The MgO sample doped with 10 mol % (Li 0.3 Na 0.6 K 0.1 )NO 3 was demonstrated to possess the highest CO 2 uptake (up to 16.8 mmol g −1 ), which is the highest value reported for MgO based adsorbents in the literature. The CO 2 adsorption/ desorption cycling stability was studied using both temperature swing adsorption (TSA) and pressure swing adsorption (PSA). The morphology and structure of the optimized adsorbent, 10 mol % (Li 0.3 Na 0.6 K 0.1 )NO 3 • MgO, were characterized thoroughly using XRD, SEM, FTIR, and BET analyses. The thermal stability of doped alkali nitrates was investigated via temperature program desorption and XRD analysis, which indicated that the phase status of the molten salts is crucial for the marked improvement in CO 2 capture capacity of MgO.
Obesity, which affects over one-third of reproductive-age women, has negative effects on reproduction and results in oocyte defects in both mice and humans. In this study, we used a mouse model to examine whether the adverse effects of an obesogenic diet, specifically abnormal oocyte spindle formation, mitochondrial metabolism, and lipid accumulation, can be reversed by return to normal weight and metabolic profile. Female C57BL6/J mice were placed on either a high-fat diet (HFD; 35.8% fat and 20.2% protein by nutritional content) or an isocaloric control diet (CD; 13% fat and 25% protein) for six weeks. All mice were then maintained on CD for eight weeks. We found that whereas metabolic parameters (weight, glucose tolerance, and cholesterol levels) of the HFD mice returned to normal after this “diet reversal” period, several oocyte defects were not reversible. Oocytes from the diet reversal mice demonstrated a significantly higher percentage of abnormal meiotic spindles than those from control mice. The HFD diet reversal GV oocytes also had lower mitochondrial membrane potential, lower levels of ATP and citrate, and higher percentages of abnormal lipid accumulation and distribution and abnormally distributed mitochondria than oocytes from control mice. Thus, despite normalization of weight, glucose utilization, and cholesterol levels eight weeks after switching from a high fat to a regular chow, oocytes from diet reversal mice exhibited significantly higher rates of meiotic spindle, lipid, and mitochondrial defects than found in mice maintained on regular chow. These results suggest that the negative effects of an obesogenic diet on oocyte quality are not as reversible as the overall metabolic parameters. These data may provide better insight when counseling obese women regarding reproductive options and success.
Beef semitendinosus (ST) muscle was marinated for 24 h in 2% NaCl solution, and 1.5% lactic, acetic and citric acid solutions individually and in mixed marinades for the combination of NaCl and three kinds of weak organic acids, respectively. The effectiveness of marinades on beef ST muscle was investigated. Changes in denaturation characteristics of connective tissue collagen were examined using differential scanning calorimetry; microstructural changes of collagenous fibers were observed with scanning electron microscopy; and textural properties of meat were studied by texture profile analysis. The results showed that: marinating with organic acids and NaCl increased filtering residue contents of connective tissue significantly, especially for the presence of NaCl in organic acids compared with marinating in acids alone. Meat marinated in 2% NaCl and the presence of NaCl in citric acid significantly increased the mechanical strength (MS) of connective tissue, and other marinating treatments had a significant reduction on MS.
CorrespondingMarinating resulted in denaturation of the intramuscular heat-insoluble collagen as exhibited by the lower onset (To) and peak (Tp) temperature compared with the control samples. After marinating, fiber diameter and perimysial thickness were decreased and arrangements of collagenous fibers were disordered. These changes of collagen characteristics contributed to the significant effects on meat quality and textural properties.
PRACTICAL APPLICATIONSCharacteristics of connective tissue and collagen are related to meat quality, especially for meat tenderness and texture. While marinating is recognized as a means of improving palatability by enhancing or complementing the flavor of meat, despite numerous recipes for meat marination, there are limited data concerning the effectiveness of weak organic acids and NaCl solutions on the texture of beef meat. Marinations in acidic solutions, e.g., lactic, acetic, citric acid, have been traditionally used as a means of softening and flavoring meats. These treatments decrease the mechanical resistance of meats, including those of high connective tissue content. Based on those responses, we reported the textural properties affected by characteristics changes of connective tissue and collagen by marinating with weak organic acids and NaCl. Results reported in this article would be useful either for the scientific community or for the beef processing industry.
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