Space-times admitting a 3-dimensional Lie group of conformal motions C3 acting on null orbits are studied. Coordinate expressions for the metric and the conformal Killing vectors (CKV) are provided (irrespectively of the matter content) and then all possible perfect fluid solutions are found, although none of these verify the weak and dominant energy conditions over the whole spacetime manifold...

The microflora was studied in beef stored in stainless steel containers kept under reduced pressure (20 to 30 kPa) in a modified atmosphere (70% N2 + 30% CO2 or pure CO2) at 3 to 4 degrees C and 0 to 1 degrees C at a headspace:meat volume ratio of 2:1. Samples were obtained at weekly intervals, 1 to 3 times. Total colony counts (TCC) for Pseudomonas spp. and Brochothrix thermosphacta were gener...

Modified atmosphere packaging (MAP) was used to increase the shelf life of fresh in hull pistachio nuts (Pistacia vera L.), meeting the market demand for fresh high quality products. Fresh in hull pistachio nuts were stored at 5°C and three different gaseous conditions including 10% O2, 20% CO2 and 70% N2 (MAP1), 100% CO2 (MAP2) and ambient atmosphere for 42 days. The samples of 300 g of pistac...

Carbon dioxide gas separation is important for many environmental and energy applications. Molecular dynamics simulations are used to characterize a two-dimensional hydrocarbon polymer, PG-ES1, that uses a combination of surface adsorption and narrow pores to separate carbon dioxide from nitrogen, oxygen, and methane gases. The CO2 permeance is 3 × 10(5) gas permeation units (GPU). The CO2/N2 s...

Rising levels of atmospheric CO2 are thought to increase C sinks in terrestrial ecosystems. The potential of these sinks to mitigate CO2 emissions, however, may be constrained by nutrients. By using metaanalysis, we found that elevated CO2 only causes accumulation of soil C when N is added at rates well above typical atmospheric N inputs. Similarly, elevated CO2 only enhances N2 fixation, the m...

Studying the long-term effect of elevated atmospheric CO2 concentration (e[CO2]) on wheat (Triticum aestivum L.) over multiple generations has received increasing attention. Here, five cultivars were grown under ambient (a[CO2], 400 ppm) and e[CO2] (800 ppm), respectively, for three consecutive (G1 to G3) two nitrogen (N) levels (1N 2N). Compared plants a[CO2], increased shoot biomass grain yie...

Because of the high separation performance and easy preparation, mixed-matrix membranes (MMMs) consisting of metal-organic frameworks have received much attention. In this article, we report a novel ZIF-300/PEBA MMM consisting of zeolite imidazolate framework (ZIF-300) crystals and polyether block amide (PEBA) matrix. The ZIF-300 crystal size was effectively reduced by optimizing the hydrotherm...

MIL-101Cr fully or partially (p) postsynthetically modified with nitro (-NO2) or amino (-NH2) groups was shown to be a robust, water stable, selective and enhanced carbon dioxide (CO2) adsorption material with the amine-functionality. The highly microporous amine-modified frameworks (up to 1.6 cm(3) g(-1) total pore volume) exhibit excellent thermal stability (>300 °C) with BET surface areas up...

A fully atomistic simulation study is reported to provide mechanistic insight into the superior performance experimentally observed for a polymer membrane (Carta et al., Science, 2013, 339, 303-307). The membrane namely PIM-EA-TB is produced by a shape-persistent ladder polymer of intrinsic microporosity (PIM) with rigid bridged bicyclic ethanoanthracene (EA) and Tröger's base (TB). The simulat...