Hierarchically porous carbon derived from natural Porphyra for excellent electromagnetic wave absorption

A highly efficient absorber with features including lightweight, broad bandwidth, and tunable electromagnetic property still remains challenging for practical applications. Herein, the Porphyra-derived porous carbon(PPC) was fabricated via facile procedures of low-temperature pre-carbonization combined with KOH chemical activation. The composition, microstructure, and electromagnetic wave absorption properties of the samples were elucidated based on X-ray diffraction(XRD), Raman, X-ray photoelectron spectroscopy(XPS), scanning electron microscopy(SEM), transmission electron microscopy(TEM),Brunauer-Emmer-Teller(BET), and vector network analyzer(VNA). The porosity of PPC can be readily regulated by adjusting activation temperature. The PPC obtained at 750 ℃ was composed of a threedimensional hierarchically porous carbon network. The C and N elements of natural Porphyra were introduced into the carbon skeleton during the carbonization process. The large specific surface, dopants, and three-dimensional hierarchically porous carbon network can effectively improve the impedance matching and dielectric dissipation, leading to an excellent electromagnetic wave absorption performance. Especially, the optimal reflection loss(RL) value reached –57.75 d B at 9.68 GHz with a broad bandwidth(RL< –10 d B) value of 7.60 GHz at 3.5 mm. Overall, the results indicate that the PPC can provide a new way to achieve lightweight, effective, and sustainable absorbers.

SIMULATING THE SUPPLY DISRUPTION FOR THE COORDINATED SUPPLY CHAIN

There are many disruptive accidents in the supply chain operations system and achieving the coordination of supply chain is main objective for supply chain research. While disruptive accidents have increasingly influenced the coordinated operation of the supply chain, existing research literature on the supply chain coordination is setting in a stationary environment. The answer for how the disruptive accidents affect the coordinated supply chain is given in this paper. Based on the benchmark supply chain which is coordinated by the negative incentive mechanism, we study the impacts of supply disruption on the supply chain system by using simulation approach in which two different distribution function of random variable are used to express the supply disruption. Comparison between these two simulation results and possible coordination mechanism under the supply disruption are proposed. From the perspective of supply chain risk management, we provide the inspiration for the manager.

Thiophene-functionalized porphyrin complexes as high performance electrodes for sodium ion batteries

Organic sodium-ion batteries(OSIBs)using eco-friendly organic materials as electrodes have recently received much attention.However,the practical applications of OSIBs are generally limited by the inherent disadvantages of organic electrodes,such as their low conductivity,poor stability,and high solubility in electrolytes.Herein,we presented[5,10,15,20-tetrathienylporphinato]M(II)(MTTP,M=2H,Ni)as new electrode materials in sodium-organic batteries.The incorporation of thiophene functionalized groups and nickel(II)ion in the molecular design of porphyrins enabled stable and excellent electrochemical performance in sodium storage systems.Benefiting from multiple charge storage sites and bipolar characteristics,the NiTTP anode has a reversible capacity of 434 mAh g^(-1)at a current density of 25 mA g^(-1).An excellent long-term cycling stability and high average voltage were obtained when NiTTP was used as a cathode.In a symmetrical battery,where NiTTP was used as both cathode and anode materials,a high average voltage of 2.3 V and a practical energy density of 93 Wh kg^(-1)was achieved.These results suggest that the thiophene-based porphyrin derivatives would be promising electrode materials for long-term organic sodium ion batteries for green and stable energy storage.