Recycling and utilization of coal gasification residues for fabricating Fe/C composites as novel microwave absorbents

Under the background of a transformation of the global energy structure,coal gasification technology has a wide application prospect,but its by-product,the coal gasification residue(CGR),is still not being efficiently utilized for recycling.The CGR contains abundant carbon components,which could be applied to the microwave absorption field as the carbon matrix.In this study,Fe/CGR composites are fabricated via a two-step method,including the impregnation of Fe^(3+)and the reduction process.The influence of the different loading capacities of the Fe component on the morphology and electromagnetic properties is studied.Moreover,the loading content of Fe and the surface morphology of the Fe/CGR can be reasonably controlled by adjusting the concentration of the ferric nitrate solution.Meanwhile,Fe particles are evenly inserted on the CGR framework,which expands the Fe/CGR interfaces to enhance interfacial polarization,thus further improving the microwave-absorbing(MA)properties of composites.Particularly,as the Fe^(3+)concentration is 1.0 mol/L,the Fe/CGR composite exhibits outstanding performance.The reflection loss reaches-39.3 dB at 2.5 mm,and the absorption bandwidth covers 4.1 GHz at 1.5 mm.In this study,facile processability,resource recycling,appropriately matched impedance,and excellent MA performance are achieved.Finally,the Fe/CGR composites not only enhance the recycling of the CGR but also pioneer a new path for the synthesis of excellent absorbents.

Optimizing pH-sensitive and time-dependent polymer formula of colonic pH-responsive pellets to achieve precise drug release

Time-sensitive and pH-dependent polymers are generally employed to prepare colon-site delivery system, and their coating thickness and order are very important in controlling the drug release. The traditional colon-site delivery systems consist of time-dependent polymers as inner layer and pH-sensitive polymers as outer layer. However, they suffer from low drug-loading rate and immature drug release. In this study, total alkaloids of sophora alopecuroides(TASA)-loaded pellets were prepared by extrusion-spheronization method and coated with Eudragit RS30D and Eudragit S100. Pellets using Eudragit RS30D as inner layer and Eudragit S100 as outer layer were named as ERS-ES100 TCO, while pellets with Eudragit S100 as inner layer and Eudragit RS30D as outer layer were ES100-ERS NCO. Both types of formulations with varying coating ratios and orders of Eudragit S100 and Eudragit RS30D were designed and prepared. The following in vitro drug release and SEM studies indicated that ERS-ES100 TCO(F2) with 12.8% Eudragit RS30D as inner layer and 21% Eudragit S100 as outer layer released up to 42% drug in 5 h. Interestingly, ES100-ERS NCO(F4) coated with 12.8% Eudragit S100 and 14.8% Eudragit RS30D showed optimal drug release in colon. In conclusion, ES100-ERS NCO colonic delivery system achieved reduced coating thickness and improved colonic targeting compared with traditional delivery system(ERS-ES100 TCO). In addition, the similarity factors( f 2) value of sophoridine and matrine for investigated formulation were within 50–100 and > 80, demonstrating that sophoridine and matrine in all formulations achieved a synchronous release.

Application of Multiple Evaluation in Art Classroom Teaching in Rural Primary Schools

With the reform and development of China's primary school art education,the art teaching activities have obtained constant improvement,and the multiple evaluation of art teaching plays an important role in the process of art teaching.Based on the current situation of the evaluation of art classroom teaching in rural primary schools,this article uses diversified evaluation methods,multi-dimensional evaluation subjects and multiple evaluation contents to change the traditional and single primary art classroom evaluation method,to strive to improve the quality of art classroom teaching and stimulate students'learning interests and adapt to the development needs of students with different personalities.

B and Fe co-doped Co_(2)P hollow nanocubes for nitrate electroreduction to ammonia

Nitrate(NO_(3)^(−))electroreduction reaction(NO_(3)^(−)RR)provides an attractive and sustainable route for NO_(3)^(−)pollution mitigation or energy-saved ammonia(NH3)synthesis.In this work,high-quality B and Fe co-doped Co_(2) P hollow nanocubes(B/Fe-Co_(2) P HNCs)are successfully synthesized though simultaneous boronation-phosphorization treatment,which reveal outstanding selectivity,activity,stability for the NO_(3)^(−)to NH_(3) conversion in neutral electrolyte because of big surface area,fast mass transport,superhydrophilic surface,and optimized electronic structure.B/Fe-Co_(2) P HNCs can achieve the high NH3 yield rate(22.67 mg h^(−1) mg_(cat)^(−1))as well as Faradaic efficiency(97.54%)for NO_(3)^(−)RR,greatly outperforming most of non-precious metal based NO_(3)^(−)RR electrocatalysts.

Review of organic and inorganic pollutants removal by biochar and biochar-based composites

Biochar(BC)has exhibited a great potential to remove water contaminants due to its wide availability of raw materials,high surface area,developed pore structure,and low cost.However,the application of BC for water remediation has many limita-tions.Driven by the intense desire of overcoming unfavorable factors,a growing number of researchers have carried out to produce BC-based composite materials,which not only improved the physicochemical properties of BC,but also obtained a new composite material which combined the advantages of BC and other materials.This article reviewed previous researches on BC and BC-based composite materials,and discussed in terms of the preparation methods,the physicochemical properties,the performance of contaminant removal,and underlying adsorption mechanisms.Then the recent research progress in the removal of inorganic and organic contaminants by BC and BC-based materials was also systematically reviewed.Although BC-based composite materials have shown high performance in inorganic or organic pollutants removal,the potential risks(such as stability and biological toxicity)still need to be noticed and further study.At the end of this review,future prospects for the synthesis and application of BC and BC-based materials were proposed.This review will help the new researchers systematically understand the research progress of BC and BC-based composite materials in environmental remediation.

Occurrence of bisphenol A in surface and drinking waters and its physicochemical removal technologies

Bisphenol A （BPA）, an endocrine disrupting compound, has caused wide public concerns due to its wide occurrence in environment and harmful effects. BPA has been detected in many surface waters and drinking water with the maximum concentrations up to tens of μg · L-1. The physicochemical technology options in eliminating BPA can be divided into four categories： oxidation, advanced oxidation, adsorption and membrane filtration. Each removal option has its own limitation and merits in removing BPA. Oxidation and advanced oxidation generally can remove BPA efficiently while they also have some drawbacks, such as high cost, the generation of a variety of transformation products that are even more toxic than the parent compound and difficult to be mineralized. Only few advanced oxidation methods have been reported to be able to mineralize BPA completely. Therefore, it is important not only to identify the major initial transformation products but also to assess their estrogenic activity relative to the parent compounds when oxidation methods are employed to remove BPA. Without formation of harmful by-products, physical separation methods such as activated carbon adsorption and membrane processes are able to remove BPA in water effluents and thus have potential as BPA removal technologies. However, the necessary regeneration of activated carbon and the low BPA removal efficiency when the membrane became saturated may limit the application of activated carbon adsorption and membrane processes for BPA removal. Hybrid processes, e.g. combining adsorption and biologic process or combining membrane and oxidation process, which can achieve simultaneous physical separation anddegradation of BPA, will be highly preferred in future.

Smart Cotton Fabric with CO_(2)-Responsive Wettability for Controlled Oil/Water Separation

Stimuli-responsive materials with switchable wettability have promising practical applications in oil/water separation.A novel CO_(2)-responsive cotton fabric for controlled oil/water separation was fabricated based on mussel-inspired reaction and polymerized with 2-(dimethylamino)ethyl methacrylate(DMAEMA).As expected,the modified fabric exhibited switchable hydrophilicity and hydrophobicity after CO_(2)/N_(2) alternation,and it could be used for gravity-driven CO_(2)-controlled oil/water separation.Water was selectively penetrated through the fabric and separated from oil after treating by CO_(2).A reversed wettability could be generated through simply treated with N2.It is expected that the as-prepared fabrics could be applied in smart oil/water separation due to the attractive properties of CO_(2)-switchable system.

OAM-Based Hybrid-Duplex Cognitive Frequency Hopping

In cognitive radio networks,the jamming attacks,which have the same ability with secondary users(SUs)but access the licensed channels without considering the carrier sense multiple access protocol,can disguise a primary user(PU)or SU to occupy the licensed channels,thus resulting in failing to access the licensed channels for PUs and SUs.Employing full/half duplex cognitive frequency hopping(CFH),where users sense the occupancy of licensed channels and then dynamically adjust the hopping parameters,can mitigate the hostile jamming.However,due to the explosive growth of serves and data traffic,it is very difficult to significantly increase the anti-jamming results and achieve high capacities with full/half duplex CFH for both PUs and SUs in cognitive radio networks.To achieve efficient anti-jamming and high capacities for PUs and SUs,in this paper we propose the orbital angular momentum(OAM)-based hybrid-duplex CFH scheme,which jointly uses the half-duplex cooperative sensing and full-duplex transmission modes for PUs and SUs in cognitive radio networks.Using the OAM-based hybrid-duplex CFH scheme,PUs and SUs can identify the occupancy of licensed channels with half-duplex fashion,thus significantly reducing the probability of signals jammed.Then,based on the sensing results,the signals are allowed to be transmitted and received by the same time-slots,carrier frequencies,and OAM-modes.The average capacities of PUs and SUs are derived,respectively.Extensively numerical results show that our proposed OAM-based hybrid-duplex CFH scheme can significantly increase the capacities of PUs and SUs in cognitive radio networks under hostile jamming attacks.