A superabsorbent of starch, 2-acrylamido-2-methyl-propanosulfonic acid (AMPS), and sodium acrylate was synthesized by microwave irradiation, and the effect of AMPS on the performance of the polymer was investigated. The best mass fraction of the three components was determined (starch/acrylic acid/AMPS ϭ 2 : 5 : 3). The structure of the polymer was characterized by Fourier transform infrared, 13C cross-polarization/magic-angle spinning NMR, and scanning electron microscopy, and the morphology of the surface of the sample was studied. The results showed that the morphology of the polymer was changed to some extent under microwave irradiation, and the swelling rate of the polymer synthesized by microwave polymerization was faster than the swelling rate of a polymer synthesized by a traditional method. The best absorbent capacities of the product in distilled water and a 0.9% sodium chloride solution were 450 and 53 g/g, respectively. Meanwhile, the introduction of AMPS to a superabsorbent resin was an effective method for improving the performance of the polymer.

As a novel X-ray focusing technology, lobster-eye micropore optics (MPO) feature both a wide observing field of view and true imaging capability, promising sky monitoring with significantly improved sensitivity and spatial resolution in soft X-rays. Since first proposed by Angel, the optics have been extensively studied, developed and trialed over the past decades. In this Letter, we report on the first-light results from a flight experiment of the Lobster Eye Imager for Astronomy, a pathfinder of the wide-field X-ray telescope of the Einstein Probe mission. The piggyback imager, launched in 2022 July, has a mostly unvignetted field of view of 18.°6 × 18.°6. Its spatial resolution is in the range of 4′–7′ in FWHM and the focal spot effective area is 2–3 cm2, both showing only mild fluctuations across the field of view. We present images of the Galactic center region, Sco X-1, and the diffuse Cygnus Loop nebular taken in snapshot observations over 0.5–4 keV. These are truly wide-field X-ray images of celestial bodies observed, for the first time, by a focusing imaging telescope. Initial analyses of the in-flight data show excellent agreement between the observed images and the on-ground calibration and simulations. The instrument and its characterization are briefly described, as well as the flight experiment. The results provide a solid basis for the development of the present and proposed wide-field X-ray missions using lobster-eye MPO.

Summary Extensive studies have been carried out to investigate the decomposition of biochar. Biochar properties, soil characteristics and incubation conditions are considered key factors that control the rate of biochar decomposition. However, the relative contributions of these factors to its decomposition remain unknown. Approximately 812 individual measurements of the rate of biochar decomposition were collected from 23 studies involving 13C or 14C isotope techniques to evaluate the effects of incubation conditions, soil characteristics and biochar properties on its decomposition with a boosted regression tree (BRT) model. The BRT model accounted for 95% of the variation in biochar decomposition. Incubation conditions, soil characteristics and biochar properties accounted for 41, 31 and 28% of variation in the rate of biochar decomposition, respectively. The most important single predictor of biochar decomposition was incubation time (contributing 33% to the rate), followed by soil carbon: nitrogen (C:N) ratio (9%), pyrolysis time (9%), soil N content (8%) and biochar C content (7%). The rate of decomposition of biochar decreased with time for incubation times less than 1 year. Soil with a large C content and a small C:N ratio resulted in a large rate of biochar decomposition. Type of feedstock and biochar N content had little or no effect on biochar decomposition. Our results provide further insight into the factors that affect biochar decomposition and quantify the relative contributions of these factors to it. Highlights We studied the dominant factors that control biochar decomposition with BRT modelling. We quantified relative contributions of incubation conditions, soil characteristics and biochar properties to biochar decomposition. Rate of biochar decomposition explained by incubation conditions (41%), soil characteristics (31%) and biochar properties (28%). The most important predictor of biochar decomposition was incubation time.