Performance Improvement of Fruit Ripeness Smart Label Based On Ammonium Molibdat Color Indicators

Research in fruit ripeness indicator is still experiencing especially due to major difficulties of several fruits with no color changes in its skin when it is ripen. From the previous research, there was found that ammonium molybdate [(NH4) 6Mo7O24.4H2O] embedded in the polymer matrix could be used as an indicator label to detect the ripeness of climacteric fruits base on the color change from yellow to blue and then green. However, the performance label still needs to be developed further. The surface of the label was still poor due to air or bubble trapping inside the film. It was found that mixing H2O2 and molydate agent produced air or bubble thus in this research, a pre-treatment of film solution was done to chase away the air by storing and vacuuming the solution in cold temperature and time period of storage. A variety of film drying method was also carried out to find the best temperature of the oven to produce smooth surface of the film. The sensitivity of the label to ethylene gas was improved by adding more agent solution into the film. The best form of smart labels was produced using an oven at 40°C for 18 hours. The label composition was 100 mL distilled water, 3.5 g PVOH, 2 mL glycerol, and a color indicator solution (ammonium molybdate and hydrogen peroxide ratio of 1:10) at 4 mL. The molydate solution had to be stored for 3 days in temperature of 7oC before used. The label sensitivity was improved as low as 100 ppm of pure ethylene gas. Label application in a pack of avocados showed a relationship between label color changes and fruit quality degradation. The value of hue label on days 0 to 6 changed from yellow to greenish yellow, while on the 7th to the 10th day the color of the label was still in the same color as the day of 6th. Decreasing the quality of fruit during storage can be seen from the increase in the percentage of weight loss and hardness of fruit texture.

Trapping and control of bubbles in various microfluidic applications

Active and passive techniques for bubble trapping and control in various microfluidic applications.

On the origin of the driving force in the Marangoni propelled gas bubble trapping mechanism

Particle trajectories around gas bubbles due to Marangoni induced flows of liquid.

Local artifacts in ice core methane records caused by layered bubble trapping and in situ production: a multi-site investigation

Advances in trace gas analysis allow localised, non-atmospheric features to be resolved in ice cores, superimposed on the coherent atmospheric signal. These high-frequency signals could not have survived the low-pass filter effect that gas diffusion in the firn exerts on the atmospheric history and therefore do not result from changes in the atmospheric composition at the ice sheet surface. Using continuous methane (CH4) records obtained from five polar ice cores, we characterise these non-atmospheric signals and explore their origin. Isolated samples, enriched in CH4 in the Tunu13 (Greenland) record are linked to the presence of melt layers. Melting can enrich the methane concentration due to a solubility effect, but we find that an additional in situ process is required to generate the full magnitude of these anomalies. Furthermore, in all the ice cores studied there is evidence of reproducible, decimetre-scale CH4 variability. Through a series of tests, we demonstrate that this is an artifact of layered bubble trapping in a heterogeneous-density firn column; we use the term “trapping signal” for this phenomenon. The peak-to-peak amplitude of the trapping signal is typically 5 ppb, but may exceed 40 ppb. Signal magnitude increases with atmospheric CH4 growth rate and seasonal density contrast, and decreases with accumulation rate. Significant annual periodicity is present in the CH4 variability of two Greenland ice cores, suggesting that layered gas trapping at these sites is controlled by regular, seasonal variations in the physical properties of the firn. Future analytical campaigns should anticipate high-frequency artifacts at high-melt ice core sites or during time periods with high atmospheric CH4 growth rate in order to avoid misinterpretation of such features as past changes in atmospheric composition.