Hygroscopicity of Internally Mixed Ammonium Sulfate and Secondary Organic Aerosol Particles Formed at Low and High Relative Humidity

Volatile organic matter that is suspended in the atmosphere such as α-Pinene and β-caryophyllene undergoes aging processes, as well as chemical and photooxidation reactions to create secondary organic aerosol (SOA),...

Stability evaluation of quail egg powder obtained by freeze-drying

This study aimed to produce quail egg powder by freeze-drying and to evaluate its stability in different types of flexible packages (low-density polyethylene, polypropylene and pigmented polypropylene) in high relative humidity (approximately 81%) at 25 °C during 59 days. The packages were evaluated for water vapor permeability and freeze-dried egg was characterized as to bulk density and hygroscopicity (initial time), and moisture, water activity, pH and color (until the end of storage). GAB, BET and Peleg sorption isotherm models were adjusted to the experimental data to predict monolayer moisture content in the powdered eggs. The freeze-dried quail eggs presented a little oscillation in color coordinates, reduction in pH, and increase in moisture content and water activity during storage for all packages used. No evaluated packaging was sufficiently effective as a moisture barrier. GAB and BET models fitted better to the experimental data for the freeze-dried quail egg, and the estimated monolayer moisture values were 0.0333 and 0.0227 g H2O/g solids, respectively. The powdered quail egg has industrial potential, however, it is susceptible to significant changes throughout storage when exposed to high relative humidity and conditioned in the tested packages. Commercially, as this product can be sold in regions with different temperatures and relative humidity, it is essential to consider the use of preservatives or anti-wetting agents.

Experimental study of evaporation of droplets of water ethanol solution at high relative air humidity

A change in the temperature of suspended droplets of a water solution of ethanol, evaporating at high relative humidity, is experimentally investigated using high-speed microphotography and infrared thermography. The data obtained for ethyl alcohol droplets show a significant dependence of the surface temperature of evaporating droplets on relative humidity of the ambient air. It should be noted that at high relative humidity, a significantly smaller decrease in the temperature of droplet surface than at low humidity was observed during evaporation. This relates to the processes of moisture absorption and condensation on the surface of an evaporating droplet of ethyl alcohol at high air humidity, accompanied by the release of heat.

The Effect of Some Climatic Variables and Frosts Waves on Citrus Crops

This study examined the effect of some climatic variables and their role in growing citrus fruits in northern Saudi Arabia, which showed that low temperatures accompanied by calm winds and high relative humidity as well as creeping air masses are among the most important factors that contribute to the worsening of frost. This study also dealt with hourly frost waves - a case study - based on the study of climatic data of the study area stations for one day of frost waves that occurred in the study area for the year 2008.

Effect of Mobile Carrier on the Performance of PVAm–Nanocellulose Facilitated Transport Membranes for CO2 Capture

Facilitated transport membranes obtained by coupling polyvinylamine with highly charged carboxymethylated nanocellulose fibers were studied considering both water sorption and gas permeation experiments. In particular, the effect of the L-arginine as a mobile carrier was investigated to understand possible improvements in CO2 transport across the membranes. The results show that L-arginine addition decreases the water uptake of the membrane, due to the lower polyvinylamine content, but was able to improve the CO2 transport. Tests carried on at 35 °C and high relative humidity indeed showed an increase of both CO2 permeability and selectivity with respect to nitrogen and methane. In particular, the CO2 permeability increased from 160 to about 340 Barrer when arginine loading was increased from 0 to 45 wt%. In the same conditions, selectivity with respect to nitrogen was more than doubled, increasing from 20 to 45. Minor improvements were instead obtained with respect to methane; CO2/CH4 selectivity, indeed, even in presence of the mobile carrier, was limited to about 20.