Search

In this study, polymer membrane for CO2 separation was produced by blending polyvinyl alcohol and sodium polyacrylate. Tests were conducted on the produced membranes to evaluate their CO2 and He separation performance under various conditions. The optimal amount of cesium carbonate to be added to the prepared membrane in terms of separation performance was determined. It was found that the highest performance was obtained at 85°C. Effects of other process conditions such as total pressure, CO2 partial pressure, and humidity on membrane performance were also investigated. In particular, CO2 permeance of around 3.0E–10 (m3(STP)/m2 s Pa)) and selectivity of nearly 500 were observed for the separation of CO2 and helium at the CO2 partial pressure of Ptotal of 0.1 MPa. Through the above examinations, the present study was not only produced a high-performance separation membrane, but also found test conditions under which this membrane exhibited higher separation performance. [ABSTRACT FROM AUTHOR]

BackgroundReproductive division of labor is one of the key features of social insects. Queens are adapted for reproduction while workers are adapted for foraging and colony maintenance. In many species, however, workers retain functional ovaries and can lay unfertilized male eggs or trophic eggs. Here we report for the first time on the occurrence of physogastric workers and apparent worker reproduction in the invasive yellow crazy ant Anoplolepis gracilipes (Fr. Smith). We further examined the reproductive potential and nutritional role of physogastric workers through multidisciplinary approaches including morphological characterization, laboratory manipulation, genetic analysis and behavioral observation.ResultsEgg production with two types of eggs, namely reproductive and trophic eggs, by physogastric workers was found. The reproductive egg was confirmed to be haploid and male-destined, suggesting that the workers produced males via arrhenotokous parthenogenesis as no spermatheca was discovered. Detailed observations suggested that larvae were mainly fed with trophic eggs. Along with consumption of trophic eggs by queens and other castes as part of their diet, the vital role of physogastric workers as "trophic specialist" is confirmed.ConclusionWe propose that adaptive advantages derived from worker reproduction for A. gracilipes may include 1) trophic eggs provisioned by physogastric workers likely assist colonies of A. gracilipes in overcoming unfavorable conditions such as paucity of food during critical founding stage; 2) worker-produced males are fertile and thus might offer an inclusive fitness advantage for the doomed orphaned colony.

A high-performance CO2 separation membrane was fabricated using a composite polymer composed of a crosslinked acrylic acid polymer sodium salt, sodium polyacrylate, polyvinyl alcohol, and cesium carbonate. Evaluation tests were conducted by varying the relative humidity (RH), temperature, total pressure (Ptotal), and CO2 partial pressure (PCO2) to determine optimal parameters for enhanced performance in selective CO2 permeation over He. The membrane shows a high separation performance and durability at 50% RH and 85°C, where the CO2/He selectivity exceeds 550 under conditions of Ptotal:0.1 MPa and PCO2:0.08 MPa. Furthermore, the operational stability of the membrane was evaluated at 85°C, 50% RH, Ptotal:0.7 MPa, and PCO2:0.56 MPa. The as-fabricated membrane was stable for 300 h of continuous operation in the separation performance evaluation test. The findings of this study suggest that the developed membranes can be applied for CO2 separation from gas mixtures such as CO2/H2 with high efficiency and stability. [ABSTRACT FROM AUTHOR]