Cooperative catalysis of Co single atoms and nanoparticles enables selective CAr-OCH_(3) cleavage for sustainable production of lignin-based cyclohexanols

In this work,a dual-size MOF-derived Co catalyst(0.2Co_(1-NPs)@NC)composed of single atoms(Co_(1))and highly dispersed nanoparticles(Co NPs)was prepared by in-situ Zn evaporation for the highperformance conversion of lignin-derived o-methoxyphenols(lignin oil)to cyclohexanols(up to 97%yield)via cascade demethoxylation and dearomatization.Theoretical calculations elaborated that the dual-size Co catalyst exhibited a cooperative effect in the selective demethoxylation process,in which the Co NPs could initially dissociate hydrogen at lower energies while Co1remarkably facilitated the cleavage of the C_(Ar)-OCH_(3)bond.Moreover,the intramolecular hydrogen bonds formed in the omethoxy-containing phenols were found to result in a decrease in the bond energy of the C_(Ar)-OCH_(3)bond,which was more prone to be activated by the dual-size Co sites.Notably,the pre-hydrogenated intermediate(e.g.,2-methoxycyclohexanol from guaiacol)is difficult to undergo demethoxylation,indicating that the selective C_(Ar)-OCH_(3)bond cleavage is a prerequisite for the synthesis of cyclohexanols.The 0.2Co_(1-NPs)@NC catalyst was highly recyclable with a neglect decline in activity during five consecutive cycles.This cooperative catalytic strategy based on the metal size effect opens new avenues for biomass upgrading via enhanced C-O bond cleavage of high selectivity.

Insight into the effects of electrochemical factors on host-guest interaction induced signature events in a biological nanopore

The signature events caused by host-guest interactions in the nanopore system can be used as a novel and characteristic signal in quantitative detection and analysis of various molecules.However,the effect of several electrochemical factors on the host-guest interactions in nanopore still remains unknown.Here,we systematically studied host-guest interactions,especially oscillation of DNA-azide adamantane@cucurbit[6]inα-Hemolysin nanopore under varying pH,concentration of electrolytes and counterions(Li+,Na+,K+).Our results indicate correlations between the change of pH and the duration of the oscillation signal.In addition,the asymmetric electrolyte concentration and the charge of the counterions affects the frequency of signature events in oscillation signals,and even the integrity of the protein nanopore.This study provides insight into the design of a future biosensing platform based on signature oscillation signals of the host-guest interaction within a nanopore.

Vitamin B_(9) derived nitrogen-doped graphene for metal-free aerobic oxidation of biomass-derived chemicals

A superior carbocatalyst ultrahigh N-doped graphene(NG) was prepared by a novel self-sacrificial templating method of one-step annealing vitamin B_(9).The NG catalyst with pyrolysis temperature of 800℃(abbreviated VB_(9)-NG-800) has an ultrahigh nitrogen content of 13.5 wt% and demonstrated the highest activity for the oxidation of bio-based alcohols and terpenes with molecular oxygen without any additives.Systematic characterizations and quantum-chemical calculations further manifested that high contents of graphitic N and pyridinic N species in VB_(9)-NG-800 promoted the generation of·O_(2)^(-)active species from molecular oxygen effortlessly,resulting in excellent catalytic performance for aerobic oxidation.

Federated transfer learning for disaster classification in social computing networks

Social media analytics have played an important role in disaster identification.Recent advances in deep learning(DL)technologies have been applied to design disaster classification models.However,the DL-based models are hindered by insufficient training samples,because data collection and labeling are very expensive and time-consuming.To solve this issue,a privacy-preserving federated transfer learning approach for disaster classification(FedTL)is proposed,which can allow distributed social computing nodes to collaboratively train a comprehensive model.In the FedTL,Paillier homomorphic encryption method is used to protect the social computing nodes’data privacy.In particular,the transfer learning technology is adopted as a novel application to reduce the computation and communication costs in the federated learning system.The FedTL is verified by a real disaster image dataset collected from social networks.Theoretical analyses and experiment results show that the FedTL is effective,secure,efficient.In addition,the FedTL is highly extensible and can be easily applied in other transfer learning models.

商业锂电池充电倍率与循环寿命的标度律

商用锂电池的健康管理目前存在大量亟待解决的问题,其中循环寿命的有效预测是电池管理系统的核心目标.本文通过利用商业锂电池不同快充倍率下循环寿命的实验结果,发现并提出了锂电池等效快充倍率c与循环寿命N之间的标度律关系,c=c_(0)N^(b)(即c-N准则),其中c_(0)表示电极材料极限充电倍率,b是与电池材料相关的常数.这一c-N准则,类似于固体材料疲劳中所周知的S-N曲线,适用于不同类型的商业锂电池,并通过已有的文献数据获得了验证.结合c-N准则和机器学习方法,我们发展了一种物理增强的机器学习模型,基于前面提出的c-N准则,使用首圈的充放电测试即可实现对电池循环寿命的高精度预测.这一工作为锂电池循环寿命预测、健康管理和锂电池的优化提供了基于力学原理的新思路.

Synthesis of Asymmetrical Monobenzo-Substituted Cobalt Thioporphyrazines and Their Biomimetic Catalytic Property

Two novel monobenzo porphyrazines bearing nitro and methoxyl respectively on fused benzene ring were suc- cessfully synthesized. Also, an asymmetrical porphyrazine with one butylthio branch at the pyrrolic p-position sub- stituted by hydrogen atom was successfully isolated in the course of synthesis of symmetric octakis（butylthio） porphyrazine. Their corresponding cobalt complexes were subsequently obtained and characterized. Their catalytic ability was assessed by aerobic oxidation of benzoin, showing the highest benzil yield of 95.2% for 60 min. A pos- sible mechanism was also presented from the in-situ UV-Vis spectra, in which a novel and characteristic absorption peak of metal-oxo was observed. At the same time, similar results of the extended oxidation of benzyl alcohol also confirmed the reactive mechanism.