Thermal pretreatment of willow branches impacts yield and pore development of activated carbon in subsequent activation with ZnCl_(2) via modifying cellulose structure

Development of pore structures of activated carbon(AC)from activation of biomass with ZnCl_(2) relies on content and structure of cellulose/hemicellulose in the feedstock.Thermal pretreatment of biomass could induce dehydration and/or aromatization to change the structure of cellulose/hemicellulose.This might interfere with evolution of structures of AC,which was investigated herein via thermal pretreatment of willow branch(WB)from 200 to 360℃and the subsequent activation with ZnCl_(2) at 550℃.The results showed that thermal pretreatment at 360℃(WB-360)could lead to substantial pyrolysis to form biochar,with a yield of 31.9%,accompanying with nearly complete destruction of cellulose crystals and remarkably enhanced aromatic degree.However,cellulose residual in WB-360 could still be activated to form AC-360 with specific surface area of 1837.9 m~2·g^(-1),which was lower than that in AC from activation of untreated WB(AC-blank,2077.8 m~2·g^(-1)).Nonetheless,the AC-200 from activation of WB-200 had more developed pores(2113.9 m~2·g^(-1))and superior capability for adsorption of phenol,due to increased permeability of ZnCl_(2) to the largely intact cellulose structure in WB-200.The thermal pretreatment did increase diameters of micropores of AC but reduced the overall yield of AC(26.8%for AC-blank versus 18.0%for AC-360),resulting from accelerated cracking but reduced intensity of condensation.In-situ infrared characterization of the activation showed that ZnCl_(2) mainly catalyzed dehydration,dehydrogenation,condensation,and aromatization but not cracking,suppressing the formation of derivatives of cellulose and lignin in bio-oil.The thermal pretreatment formed phenolic-OH and C=O with higher chemical innerness,which changed the reaction network in activation,shifting morphology of fibrous structures in AC-blank to“melting surface”in AC-200 or AC-280.

A cascade of in situ conversion of bicarbonate to CO_(2) and CO_(2) electroreduction in a flow cell with a Ni-N-S catalyst

Combination of CO_(2) capture using inorganic alkali with subsequently electrochemical conversion of the resultant HCO_(3)^(-)to high-value chemicals is a promising route of low cost and high efficiency.The electrochemical reduction of HCO_(3)^(-)is challenging due to the inaccessible of negatively charged molecular groups to the electrode surface.Herein,we adopt a comprehensive strategy to tackle this challenge,i.e.,cascade of in situ chemical conversion of HCO_(3)^(-)to CO_(2) and CO_(2) electrochemical reduction in a flow cell.With a tailored Ni-N-S single atom catalyst(SACs),where sulfur(S)atoms located in the second shell of Ni center,the CO_(2)electroreduction(CO_(2)ER)to CO is boosted.The experimental results and density functional theory(DFT)calculations reveal that the introduction of S increases the p electron density of N atoms near Ni atom,thereby stabilizing^(*)H over N and boosting the first proton coupled electron transfer process of CO_(2)ER,i.e.,^(*)+e^(-)+^(*)H+^(*)CO_(2)→^(*)COOH.As a result,the obtained catalyst exhibits a high faradaic efficiency(FE_(CO)~98%)and a low overpotential of 425 mV for CO production as well as a superior turnover frequency(TOF)of 47397 h^(-1),outcompeting most of the reported Ni SACs.More importantly,an extremely high FECOof 90%is achieved at 50 mA cm^(-2)in the designed membrane electrode assembly(MEA)cascade electrolyzer fed with liquid bicarbonate.This work not only highlights the significant role of the second coordination on the first coordination shell of the central metal for CO_(2)ER,but also provides an alternative and feasible strategy to realize the electrochemical conversion of HCO_(3)^(-)to high-value chemicals.

Deep Learning-Based Secure Transmission Strategy with Sensor-Transmission-Computing Linkage for Power Internet of Things

The automatic collection of power grid situation information, along with real-time multimedia interaction between the front and back ends during the accident handling process, has generated a massive amount of power grid data. While wireless communication offers a convenient channel for grid terminal access and data transmission, it is important to note that the bandwidth of wireless communication is limited. Additionally, the broadcast nature of wireless transmission raises concerns about the potential for unauthorized eavesdropping during data transmission. To address these challenges and achieve reliable, secure, and real-time transmission of power grid data, an intelligent security transmission strategy with sensor-transmission-computing linkage is proposed in this paper. The primary objective of this strategy is to maximize the confidentiality capacity of the system. To tackle this, an optimization problem is formulated, taking into consideration interruption probability and interception probability as constraints. To efficiently solve this optimization problem, a low-complexity algorithm rooted in deep reinforcement learning is designed, which aims to derive a suboptimal solution for the problem at hand. Ultimately, through simulation results, the validity of the proposed strategy in guaranteed communication security, stability, and timeliness is substantiated. The results confirm that the proposed intelligent security transmission strategy significantly contributes to the safeguarding of communication integrity, system stability, and timely data delivery.

The Wireless Power Transmission on the Wristto-Forehead Path Based on the Body Channel

The body channel based wireless power transfer(BC-WPT)method utilizes the human body as the medium to transfer power for bioelectronics,which can achieve a lower transmission loss due to its higher conductivity.However,except for the channel length,different on-body loca-tions of the transmitter and receiver also influence the power supply performance.This paper fo-cuses on the wrist-to-forehead path to show the potential of BC-WPT for the brain bioelectronics such as the brain computer interface device.The channel characteristics from 10 MHz to 60 MHz are measured by a vector network analyzer(VNA)and a prototype BC-WPT system with differ-ent copper electrodes and the lowest power loss locates between-22 dB and-33 dB.Furthermore,the minimum path loss limit is simulated in Advanced Design System(ADS)software and the low-est optimum path loss can reach nearly-13 dB.Finally,a rectifier circuit is also built at the receiv-er side to harvest d.c.voltage.The results show that the open-circuit voltage(OCV)can reach 1.75 V with the transmitter of 50Ωoutput impedance supplying 5V_(pp)sine voltage at 60 MHz when adopt-ing 1 cm-diameter circular electrodes.

精氨酸代谢调控蛋白ArgR调控嗜热链球菌胞外多糖合成

【目的】研究精氨酸代谢调控蛋白ArgR对嗜热链球菌胞外多糖(EPS)合成的调控作用。【方法】利用大肠杆菌异源表达嗜热链球菌ArgR蛋白,通过尿素变性-复性和Ni2+亲和层析纯化。采用凝胶电泳迁移(EMSA)和生物膜层干涉(BLI)分析ArgR和eps基因簇中PepsA启动子的相互作用和动力学信息。构建过表达和弱化argR基因菌株,利用苯酚-硫酸法测定其合成EPS差异。【结果】大肠杆菌异源表达的ArgR为包涵体,使用尿素变性-复性纯化可获得2.95 mg/mL可溶性蛋白;EMSA和BLI结果显示ArgR和启动子PepsA有特异性结合,且结合因解离水平低而稳定;过表达argR基因可显著降低嗜热链球菌EPS合成,而弱化argR基因则提高EPS合成。【结论】本研究表明ArgR能特异性结合嗜热链球菌eps基因簇启动子,并负调控EPS生物合成。

Selective recognition of methyl viologen by an endo-functionalized naphthobox

Highly selective binding of structurally similar substrates is common for biomolecular recognition,but is often challenging to realize in synthetic hosts.Herein,we report highly selective binding of methyl viologen over other analogues by an endo-functionalized naphthobox.X-ray single crystal structure and Density Functional Theory(DFT)calculations revealed that the endo-functionalized groups in the cavity of the naphthobox is important for the high binding selectivity through the formation of multiple C-H…N,C-H…π,andπ…πinteractions with methyl viologen.

Metal oxyacid salts-confined pyrolysis towards hierarchical porous metal oxide@carbon(MO@C)composites as lithium-ion battery anodes

Transition metal oxides(TMOs)have been thought of potential anodic materials for lithium-ion batteries(LIBs)owing to their intriguing properties.However,the limited conductivity and drastic volume change still hinder their practical applications.Herein,a metal oxyacid salts-confined pyrolysis strategy is proposed to construct hierarchical porous metal oxide@carbon(MO@C,MO=MoO_(2),V_(2)O_(5),WO_(3))composites for solving the aforementioned problems.A water-evaporation-induced self-assembly mechanism has been put forward for fabricating the MO@polyvinyl pyrrolidone(PVP)@SiO_(2)precursors.After the following pyrolysis and etching process,small MO nanoparticles can be successfully encapsulated in the hierarchical porous carbon framework.Profiting from the synergistic effect of MO nanoparticles and highly conductive carbon framework,MO@C composites show excellent electrochemical properties.For example,the as-obtained MoO_(2)@C composite exhibits a large discharge capacity(1513.7 mAh·g^(−1)at 0.1 A·g^(−1)),good rate ability(443.5 mAh·g^(−1)at 5.0 A·g^(−1)),supernal long-lived stability(669.1 mAh·g^(−1)after 1000 cycles at 1.0 A·g^(−1)).This work will inspire the design of novel anode materials for high-performance LIBs.