1.
Preparation of polyacrylic acid-grafted-acryloyl/hemicellulose (PAA-g-AH) hybrid films with high oxygen barrier performance.
Liu, R, Du, J, Zhang, Z, Li, H, Lu, J, Cheng, Y, Lv, Y, Wang, H
Carbohydrate polymers. 2019;:83-88
Abstract
Developing high-performance oxygen barrier films using biomass-based materials is crucial for the development of green and sustainable society. Herein, we develop a strategy to synthesize polyacrylic acid-grafted-acryloyl/hemicellulose composites (PAA-g-AH) as film materials with excellent oxygen barrier property. The as-synthesized films were extensively characterized by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), gel permeation chromatography (GPC), 1H nuclear magnetic resonance (1H NMR), mechanical test, light transmittance and oxygen transmission rate (OTR) measurement. All these testing results showed that the optimum film exhibit great oxygen barrier property with a low OTR value of 0.25 ± 0.01 cm3* μm/(m2*d*kPa), which was much lower than that of pure PAA film. Moreover, the hybrid films possess well mechanical strength, light transmittance and recycle usage properties. Experimental results indicated that the as-synthesized films have great potential applications in several fields as packaging materials, such as drug, food and electronic products.
2.
Physiological characteristics of Magnetospirillum gryphiswaldense MSR-1 that control cell growth under high-iron and low-oxygen conditions.
Wang, Q, Wang, X, Zhang, W, Li, X, Zhou, Y, Li, D, Wang, Y, Tian, J, Jiang, W, Zhang, Z, et al
Scientific reports. 2017;(1):2800
Abstract
Magnetosome formation by Magnetospirillum gryphiswaldense MSR-1 is dependent on iron and oxygen levels. We used transcriptome to evaluate transcriptional profiles of magnetic and non-magnetic MSR-1 cells cultured under high-iron and low-iron conditions. A total of 80 differentially expressed genes (DEGs) were identified, including 53 upregulated and 27 downregulated under high-iron condition. These DEGs belonged to the functional categories of biological regulation, oxidation-reduction process, and ion binding and transport, and were involved in sulfur metabolism and cysteine/methionine metabolism. Comparison with our previous results from transcriptome data under oxygen-controlled conditions indicated that transcription of mam or mms was not regulated by oxygen or iron signals. 17 common DEGs in iron- and oxygen-transcriptomes were involved in energy production, iron transport, and iron metabolism. Some unknown-function DEGs participate in iron transport and metabolism, and some are potential biomarkers for identification of Magnetospirillum strains. IrrA and IrrB regulate iron transport in response to low-oxygen and high-iron signals, respectively. Six transcription factors were predicted to regulate DEGs. Fur and Crp particularly co-regulate DEGs in response to changes in iron or oxygen levels, in a proposed joint regulatory network of DEGs. Our findings provide new insights into biomineralization processes under high- vs. low-iron conditions in magnetotactic bacteria.
3.
Flame temperature measurements by radar resonance-enhanced multiphoton ionization of molecular oxygen.
Wu, Y, Sawyer, J, Zhang, Z, Adams, SF
Applied optics. 2012;(28):6864-9
Abstract
Here we report nonintrusive local rotational temperature measurements of molecular oxygen, based on coherent microwave scattering (radar) from resonance-enhanced multiphoton ionization (REMPI) in room air and hydrogen/air flames. Analyses of the rotational line strengths of the two-photon molecular oxygen C(3)Π(v=2)←X(3)Σ(v'=0) transition have been used to determine the hyperfine rotational state distribution of the ground X(3)Σ(v'=0) state. Rotationally resolved 2+1 REMPI spectra of the molecular oxygen C(3)Π(v=2)←X(3)Σ(v'=0) transition at different temperatures were obtained experimentally by radar REMPI. Rotational temperatures have been determined from the resulting Boltzmann plots. The measurements in general had an accuracy of ~±60 K in the hydrogen/air flames at various equivalence ratios. Discussions about the decreased accuracy for the temperature measurement at elevated temperatures have been presented.