Effect of perforation packaging on quality of fresh-cut carrot during storage

The aim of this work was to evaluate the effect of packaging perforation on quality of carrot slices during cold storage at 5 °C. Polyethylene bags with different number of perforations (3, 4, and 6) were used in this experiment. Headspace oxygen concentration, respiration, weight loss, surface color, firmness, pH, and soluble solid content were examined throughout storage. It was observed, that all the investigated packaging were effective in maintaining the quality of carrot slices compared to the control. There was no symptom of decay until 12 days. In addition, pH, soluble solid content, and firmness showed nonsignificant change. Moreover, weight loss of packed carrot slices was below 2% after 12 days of storage. Packed carrot had better appearance at the end of experiment (12 days) than that of control.

Influence of ventilation in H2S exposure and emissions from a gravity sewer

This study was carried out to evaluate the effect of natural ventilation and intermittent pumping events in hydrogen sulfide and methane dynamics, in terms of system operation and risk of gas exposure. Work was conducted in a full scale gravity sewer downstream of pumping stations, in Portugal. Different ventilation rates and locations were assessed, as well as H2S removal rates and potential exposure risk, through the opening of distinct manhole covers. Increased ventilation, resulting from opening of one manhole cover, saw a 38% increase in average pipe air velocity peaks, doubling the estimated rate of air turnovers per day, accompanied by an increase of nearly 20% in H2S average removal rate. Simultaneous opening of two manhole covers induced similar airflow rates through the vent stack, but different rates throughout the pipe. H2S removal rates were also found to differ, according to location of open manholes, but also initial H2S headspace concentration. Under more unfavourable conditions, natural ventilation did not suffice in attaining recommended safety concentrations, regardless of number and location of open manhole covers. H2S concentrations above defined thresholds were verified for all studied setups. Headspace oxygen concentrations below an 18.5% asphyxiation threshold also occasionally occurred, even at manholes immediately downstream of ventilation point.

Effect of Formulation Factors and Oxygen Levels on the Stability of Aqueous Injectable Solution Containing Pemetrexed

The aim of this study was to investigate the effects of various parameters at each control strategy in drug product degradation on the stability of pemetrexed in injectable aqueous solution. A forced degradation study confirmed that oxidation is the main mechanism responsible for the degradation of pemetrexed in aqueous solutions. As control strategies, the antioxidant levels, drug concentration, pH of the control formulation, dissolved oxygen (DO) levels in the control process, and headspace oxygen levels in the control packaging were varied, and their effects on the stability of pemetrexed were evaluated. Sodium sulfite was found to be particularly effective in preventing the color change, and N-acetylcysteine (NAC) had a significant effect in preventing chemical degradation. The sulfite and NAC were found to stabilize pemetrexed in the aqueous solution by acting as sacrificial reductants. A pH below 6 caused significant degradation. The stability of pemetrexed in the solution increased as the concentration of the drug increased from 12.5 to 50 mg/mL. In addition, the DO levels in the solution were controlled by nitrogen purging, and the oxygen levels in headspace were controlled by nitrogen headspace, which also had significant positive effects in improving the stability of the pemetrexed solution; thus, it was confirmed that molecular oxygen is involved in the rate-limiting oxidation step. Based on these results obtained by observing the effects of various control strategies, the optimal formulation of an injectable solution of pemetrexed is suggested as follows: sodium sulfite at 0.06 mg/mL, as an antioxidant for prevention of color change; NAC at 1.63 mg/mL, as an antioxidant for prevention of chemical degradation; pH range 7–8; DO levels below 1 ppm; and headspace oxygen levels below 1%. In conclusion, it can be suggested that this study, which includes well-designed control strategies, can lead to a better understanding of the complex degradation mechanism of pemetrexed; thus, it can lead to the development of an injectable solution formulation of pemetrexed, with improved stability.