Production of Lignin-Derived Functional Material for Efficient Electromagnetic Wave Absorption with an Ultralow Filler Ratio.

Industrial lignin, a by-product of pulping for papermaking fibers or of second-generation ethanol production, is primarily served as a low-grade combustible energy source. The fabrication of high-value-added functional materials with industrial lignin is still a challenge. Herein, a three-dimensional hierarchical lignin-derived porous carbon (HLPC) was prepared with lignosulfonate as the carbon source and MgCO3 as the template. The uniform mixing of precursor and template agent resulted in the construction of a three-dimensional hierarchical porous structure. HLPC presented excellent electromagnetic wave (EMW) absorption performance. With a low filler content of 7 wt%, HLPC showed a minimum reflection loss (RL) value of -41.8 dB (1.7 mm, 13.8 GHz), and a maximum effective absorption bandwidth (EAB) of 4.53 GHz (1.6 mm). In addition, the enhancement mechanism of HLPC for EMW absorption was also explored through comparing the morphology and electromagnetic parameters of lignin-derived carbon (LC) and lignin-derived porous carbon (LPC). The three-dimensional hierarchical porous structure endowed the carbon with a high pore volume, resulting in an abundant gas-solid interface between air and carbon for interfacial polarization. This structure also provided conductive networks for conduction loss. This work offers a strategy to synthesize biomass-based carbon for high-performance EMW absorption.

Effect of Torrefaction on the Physiochemical Characteristics and Pyrolysis of the Corn Stalk.

Torrefaction of biomass is one of the most promising pretreatment methods for deriving biofuels from biomass via thermochemical conversion processes. In this work, the changes in physicochemical properties and morphology features of the torrefied corn stalk, the changes in physicochemical properties and morphology features of the torrefied corn stalk were investigated. The results of this study showed that the elemental content and proximate analysis of the torrefied corn stalk significantly changed compared with those of the raw corn stalk. In particular, at 300 °C, the volatile content decreased to 41.79%, while the fixed carbon content and higher heating value increased to 42.22% and 21.31 MJ/kg, respectively. The H/C and O/C molar ratios of torrefied corn stalk at the 300 °C were drastically reduced to 0.99 and 0.27, respectively, which are similar to those of conventional coals in China. Numerous cracks and pores were observed in the sample surface of torrefied corn stalk at the torrefaction temperature range of 275 °C-300 °C, which could facilitate the potential application of the sample in the adsorption process and promote the release of gas products in pyrolysis. In the pyrolysis phase, the liquid products of the torrefied corn stalk decreased, but the H2/CO ratio and the lower heating value of the torrefied corn stalk increased compared with those of the raw corn stalk. This work paves a new strategy for the investigation of the effect of torrefaction on the physiochemical characteristics and pyrolysis of the corn stalk, highlighting the application potential in the conversion of biomass.

Preparation and curing behaviour of microencapsulated curing agents for cold-mixed epoxy asphalt.

This study aimed to improve control over the curing behaviour of cold-mixed epoxy asphalt by using a microencapsulated curing agent (2-PZ@PC). Prepared through solvent evaporation, the 2-PZ@PC microcapsules had 2-phenylimidazole as the core material and polycarbonate as the shell material. The research examined the impact of core-shell mass ratio on microcapsule morphology and composition. Various equations, including the kinetics equation, Kissinger equation, Flynn-Wall-Ozawa, and Crane equations, were employed to assess the sustained release effect of 2-PZ@PC microcapsules on epoxy resin curing behaviour. Fluorescence microscopy and viscosity experiments were used to observe the release state of microcapsules and confirm the retardation phenomenon during construction. Optimal 2-PZ@PC microcapsules displayed a smooth spherical morphology and a maximum encapsulation rate of 32 wt% at a 1:1 core-shell ratio. The microencapsulated curing agent effectively regulated cold-mixed epoxy asphalt's curing behaviour, enhancing retention time control and application reliability.

Effect of microstructure-scale features on lignin fluorescence for preparation of high fluorescence efficiency lignin-based nanomaterials.

As a natural fluorescent material, the practical application of lignin fluorescence was hindered due to the low fluorescence quantum yield (QY). Inspired by its aggregation fluorescence behavior, the effect of microstructure-scale on lignin fluorescence was studied from two levels, the molecular weight and colloidal sphere. It was demonstrated that with the decrease of lignin microstructure-scale, the non-radiative dissipation and reabsorption effect of lignin fluorescence would be weak, resulting in high emission efficiency. On this basis, hydrogenolysis was used to obtain small molecular fragments and reduce content of reabsorbing groups of lignin, of which the QY was greatly increased by 35 times to about 12%. In addition, the emission peak of lignin was the fluorescence addition of its main structural units. The long-wavelength emission peak was often the illusion from the reabsorption effect but not duo to the formation of conjugated structure. This work provided a potential method for the preparation of high QY lignin and an in-depth understanding of lignin fluorescence.

Eliminating the Detrimental Effect of Secondary Doping on PEDOT : PSS Hole Transporting Material Performance.

Secondary doping has a long history of use in conductivity enhancement in poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS). However, very little research has addressed its detrimental effect on application performance of PEDOT : PSS in organic solar cells. Herein, it was shown that the uneven drying of secondary dopant-water mixture results in a nonuniform/continuous film structure, causing severe damage to the device efficiencies (dropping about 8 and 23 % for poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) : 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITIC) and poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b']dithio-phene))-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)-benzo[1,2-c:4,5-c']dithiophene-4,8-dione))](PM6) : (3,9-bis(1-oxo-2-methylene-3-(1,1-dicyanomethylene)-5,6-difluoroindanone)-5,5,11,11-tetrakis(4-n-hexylphenyl)-dithieno[2,3d:2',3'd']-s-indaceno[1,2b:5,6b']dithiophene (IT-4F) cells, respectively) and thermal stabilities. Moreover, a simple yet robust dialysis treatment was proposed to solve the issue of noncontinuity and retain the secondary doping's advantages of quinoid structure simultaneously, thus demonstrating a significant enhancement in device performance. This study will be of great importance to the future exploration of the next generation of post-treatment strategy.

Ovarian hormone modulates 5-hydroxytryptamine 3 receptors mRNA expression in rat colon with restraint stress-induced bowel dysfunction.

AIM: To examine the effects of ovarian hormone on the expression of 5-hydroxytryptamine 3 receptors (5-HT3R) in rat colon of restraint stress-induced bowel dysfunction. METHODS: Twenty-four female Sprague-Dawley rats were randomly divided into three groups of 8 each: sham operation, ovariectomy (OVX) and ovariectomy with estrogen (E2) and progesterone (P) replacement therapy (OVX+E2+P). The rats were subjected to 1-h restraint stress 4 wk after operation. The changes of defecation were monitored by collection of fecal pellets. The gonadal steroids were measured in duplicate by radioimmunoassay (RIA). The expression of 5-HT3R mRNA in the colon was studied by RT-PCR. RESULTS: Compared with sham group and OVX+E2+P group, OVX group showed increase in fecal pellets and decrease in the time of vitreous pellets excretion (P<0.01). Serum levels of E2 and P were suppressed in OVX group and restored following treatment with ovarian steroids (P<0.01), and the levels of 5-HT3R mRNA in the colon of ovariectomized rats were significantly increased, the expression of 5-HT3R mRNA was significantly decreased in hormone replacement therapy group (P<0.01). CONCLUSION: Ovarian hormone plays a role in the regulation of 5-HT3R expressions in restraint stress-induced bowel dysfunction of rats. The interactions between ovarian steroids and gastrointestinal tract may have major pathophysiological implications in 5-HT-related disorders, such as irritable bowel syndrome (IBS).