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Polymer‐based afterglow materials with persistent room temperature phosphorescence (pRTP) have attracted ever‐increasing attention due to their excellent mechanical property, suitability for large‐area production, and diverse processing methods. However, most pRTP polymers were solution‐processed into the films via casting. Herein, a simple processing method of melt‐pressing was proposed, which can improve the phosphorescence of various emitters when doped into polyamide‐12 (PA12) or its copolymer PA4 matrix. Notably, for Be@PA4 and Ch@PA4 (benzo[c]phenanthrene, Be and chrysene, Ch), their casted films did not show any afterglow, while the melt‐pressed ones exhibited bright afterglow of over 4.0 s, even if there were no hydrogen or ionic interaction between the emitters and the matrix. Detailed investigations demonstrate the melt‐pressing procedure can increase the non‐covalent interaction among the matrix as well as offer a rigid and dense environment. The melt‐pressed RTP improvement strategy was also applied to other polar polymers. Additionally, the melt‐pressing method would be of great potential in high‐level anti‐counterfeiting like preparing colorful camouflage patterns. Therefore, we offered a feasible method of melt‐pressing to improve the phosphorescence of polymeric materials without a change in chemical composition or feeding ratio. This work also gained a deeper understanding of the luminescence of polymer‐based systems. [ABSTRACT FROM AUTHOR]

Char gasification is a feasible technology to recycle CO2 and utilize biomass energy. However, the impact of different species of biomass on the gasification is still unclear. For the assessment of the feedstock effect on CO2 gasification, the present work prepared over 40 different wood char samples on a high temperature (around 1523 K) flame reactor, which simulate the rapid heating rates experienced in industrial reactors. Then, the curves of conversion (X) and conversion rate (dX/dt) versus temperature, and the conversion rate versus fractional conversion were derived from the linear non-isothermal thermogravimetric analysis. Three models (volumetric model, grain model, and random pore model) are examined for their goodness of fit between the model and experimental data, and their estimated activation energy. Finally, links between different biomass property parameters and different reactivity indexes were investigated. The results obtained show that different feedstocks result in different gasification reactivities of the resultant chars, with T50 and Tmax varying in a wide range of about 170 K and 200 K. But when conversion is plotted against dimensionless temperature, regardless of the feedstock origin, all the experimental plots can be described by only one curve for X = 0.2–0.95. We attributed the slightly superior prediction of the RPM to the increased amount of adjustable kinetic parameters, but lower E values were obtained by using RPM. In addition to the potassium content, the cellulose and lignin contents of the feedstock were found to have relatively high correlation with the char reactivity indexes. [ABSTRACT FROM AUTHOR]

An efficient near-infrared (NIR) afterglow emission at over 750 nm is highly valuable for the advanced detection technology. Herein, a new kind of organic NIR afterglow system with persistent emission (0.16 s) at 808 nm is prepared by using a red room temperature phosphorescence (RTP) excimer as a donor and a NIR dye cyanine 7 (Cy7) as an acceptor. In the pyren-1-ylboronic acid@poly(vinyl alcohol) (PYB@PVA) system, its red persistent RTP emission at over 590 nm is proved to be derived from the triplet excimer of PYB. So, the bright NIR afterglow is achieved via only a single triplet-to-singlet Förster-resonance energy transfer process between PYB@PVA and Cy7. Moreover, PYB2@PVA with more triplet excimers is beneficial to improve NIR emission intensity with a quantum yield of 1.6%. This work demonstrates that exploiting triplet excimers is meaningful to develop purely organic red or NIR afterglow materials with the emission at a long wavelength. [ABSTRACT FROM AUTHOR]

The Förster resonance energy transfer (FRET) process has been utilized to construct host–guest systems with stimuli-responsive room-temperature phosphorescence (RTP). However, only two guests have been reported for these systems. Thus, the design of new guests and investigation of their molecular structural effects on their RTP properties has become an important and challenging work for improving their stimuli-responsive performance. In this work, a series of asymmetric diarylamine guests were designed and prepared for the DMAP host to construct host–guest systems, which exhibited stimuli-responsive RTP to heating, pressing, grinding and pH values; and it was revealed that the FRET process changes were the key to the stimulus-responsive RTP, by careful investigation. Interestingly, the host–guest system of DMAP/MDPA-Ph showed the best RTP performance, in which the T1h state of the host is close to the center between S1g and T1g states of the guest. Based on the time-resolved characteristics of RTP of these systems, anti-counterfeiting applications could be achieved through screen-printing or stamping processes. This work thus opened up a way to achieve excellent performance of stimulus-responsive RTP materials through molecular design of the guest. [ABSTRACT FROM AUTHOR]

Mesoscale eddies have essential effects on the distribution of the different sizes of phytoplankton and the status of phytoplankton physiology. The impact of mesoscale eddies on phytoplankton size and physiological level in the northern South China Sea is analyzed based on satellite data and HYCOM-simulated results from 2003 to 2018. The results show that there are higher nanophytoplankton levels for high and low nonlinearity in the center of cyclonic eddies. At the same time, the growth rate of phytoplankton increased, and the assimilation of phytoplankton decreased. Moreover, in the center of anticyclonic eddies, a lower nanophytoplankton level is observed in both high and low nonlinearity. At the same time, the growth rate of phytoplankton decreased, and the assimilation of phytoplankton increased. In addition, there is a higher nanophytoplankton level in the mode-water eddy, while the growth rate of phytoplankton is increased, and the assimilation of phytoplankton is decreased. [ABSTRACT FROM AUTHOR]

In order to better understand the impact of the carbon structure of char on its combustion reactivity, 14 types of organic model compounds were pyrolyzed under temperatures of 530 °C, 800 °C and 1028 °C at heating rates of 10 °C/min and 65 °C/s, respectively. The carbon structure and the oxidation reactivity of the produced char were determined by respective Raman spectroscopy and thermogravimetric analysis (TGA) methods. The relationships between different reactivity indexes and Raman spectral parameters have been assessed. The results reveal that changes in pyrolysis temperature and heating rate would result in certain evolution of the graphitization degree of char. Good correlations have been discovered between the Raman spectral parameters (A D /A ALL , A GL /A ALL , A (S+R+SL+VR+VL) /A D , and A (GR+VL+VR) /A D) and the combustion characteristic temperatures (T i , T b , T 50 , and T max). From the correlations above, Raman spectral parameter A (GR+VL+VR) /A D is found to be the best correlated to the char combustion characteristic temperature T b with R2 of around 0.76. • Char from 14 types of organic model compounds was studied. • Char yield rises with a higher pyrolysis temperature and a lower heating rate. • Char structure becomes ordered at a high temperature or slow heating rate. • Lower H/C and O/C reflect higher condensation degree of aromatic rings in char. • Higher ordered char structure leads to a higher oxidation temperature. [ABSTRACT FROM AUTHOR]

Developing stable room-temperature phosphorescence (RTP) emission without being affected by moisture and mechanical force remains a great challenge for purely organic systems, due to their triplet states sensitive to the infinitesimal motion of phosphors and the oxygen quencher. We report a kind of highly robust phosphorescent systems, by doping a rigid phosphor into a copolymer (polyvinyl butyral resin) matrix with a balance of mutually exclusive features, including a rigidly hydrophilic hydrogen bond network and elastically hydrophobic constituent. Impressively, these RTP polymeric films have superior adhesive ability on various surfaces and showed reversible photoactivated RTP with lifetimes up to 5.82 seconds, which can be used as in situ modulated anticounterfeit labels. They can maintain a bright afterglow for over 25.0 seconds under various practical conditions, such as storage in refrigerators, soaking in natural water for a month, or even being subjected to strong collisions and impacts. These findings provide deep insights for developing stable ultralong RTP materials with desirable comprehensive performance.