Lignin‐derived carbon with pyridine N‐B doping and a nanosandwich structure for high and stable lithium storage

Biomass‐derived carbon is a promising electrode material in energy storage devices.However,how to improve its low capacity and stability,and slow diffusion kinetics during lithium storage remains a challenge.In this research,we propose a“self‐assembly‐template”method to prepare B,N codoped porous carbon(BN‐C)with a nanosandwich structure and abundant pyridinic N‐B species.The nanosandwich structure can increase powder density and cycle stability by constructing a stable solid electrolyte interphase film,shortening the Li^(+) diffusion pathway,and accommodating volume expansion during repeated charging/discharging.The abundant pyridinic N‐B species can simultaneously promote the adsorption/desorption of Li^(+)/PF_(6)^(−) and reduce the diffusion barrier.The BN‐C electrode showed a high lithium‐ion storage capacity of above 1140 mAh g^(−1) at 0.05 A g^(−1) and superior stability(96.5% retained after 2000 cycles).Moreover,owing to the synergistic effect of the nanosandwich structure and pyridinic N‐B species,the assembled symmetrical BN‐C//BN‐C full cell shows a high energy density of 234.7Wh kg^(−1),high power density of 39.38 kW kg−1,and excellent cycling stability,superior to most of the other cells reported in the literature.As the density functional theory simulation demonstrated,pyridinic N‐B shows enhanced adsorption activity for Li^(+) and PF_(6)^(−),which promotes an increase in the capacity of the anode and cathode,respectively.Meanwhile,the relatively lower diffusion barrier of pyridinic N‐B promotes Li^(+) migration,resulting in good rate performance.Therefore,this study provides a new approach for the synergistic modulation of a nanostructure and an active site simultaneously to fabricate the carbon electrode material in energy storage devices.

Porous heterostructure of graphene/hexagonal boron nitride as an efficient electrocatalyst for hydrogen peroxide generation

Compared with the traditional heteroatom doping,employing heterostructure is a new modulating approach for carbon-based electrocatalysts.Herein,a facile ball milling-assisted route is proposed to synthesize porous carbon materials composed of abundant graphene/hexagonal boron nitride(G/h-BN)heterostructures.Metal Ni powder and nanoscale h-BN sheets are used as a catalytic substrate/hard template and“nucleation seed”for the formation of the heterostructure,respectively.As-prepared G/h-BN heterostructures exhibit enhanced electrocatalytic activity toward H_(2)O_(2) generation with 86%-95%selectivity at the range of 0.45-0.75 V versus reversible hydrogen electrode(RHE)and a positive onset potential of 0.79 versus RHE(defined at a ring current density of 0.3 mA cm^(-2))in the alkaline solution.In a flow cell,G/h-BN heterostructured electrocatalyst has a H_(2)O_(2) production rate of up to 762 mmol g_(catalyst)^(-1) h^(-1) and Faradaic efficiency of over 75%during 12 h testing,superior to the reported carbon-based electrocatalysts.The density functional theory simulation suggests that the B atoms at the interface of the G/h-BN heterostructure are the key active sites.This research provides a new route to activate carbon catalysts toward highly active and selective O_(2)-to-H_(2)O_(2) conversion.

Electrochemical Biorefinery toward Chemicals Synthesis and Bio-Oil Upgrading from Lignin

Recalcitrance and the inherent heterogeneity of lignin structure are the major bottlenecks to impede the popularization of lignin-based chemicals production processes.Recent works suggested a promising pathway for lignin depolymerization and lignin-derived bio-oil upgrading via an electrochemical biorefinery(a process in which lignin valorization is performed via electrochemical oxidation or reduction).This review presents the progress on chemicals synthesis and bio-oil upgrading from lignin by an electrochemical biorefinery,relating to the lignin biosynthesis pathway,reaction pathway of lignin electrochemical conversion,inner-sphere and outer-sphere electron transfer mechanism,basic kinetics and thermodynamics in electrochemistry,and the recent embodiments analysis with the emphasis on the respective feature and limitation for lignin electrochemical oxidative and reductive conversion.Lastly,the challenge and perspective associated with lignin electrochemical biorefinery are discussed.Present-day results indicate that more work should be performed to promote efficiency,selectivity,and stability in pursuing a lignin electrochemical biorefinery.One of the most promising developing directions appears to be integrating various types of lignin electrochemical conversion strategies and other existing or evolving lignin valorization technologies.This review aims to provide more references and discussion on the development for lignin electrochemical biorefinery.

Advances in Studies on Interaction between Selenium and Heavy Metal Cadmium

Selenium is an essential functional element of the human body,and the issue of selenium accompanying heavy metals is receiving much concern.This paper expounded the form of existence of selenium and cadmium in soil and influencing factors of their bioavailability,and further elaborated the interaction between selenium and cadmium.On the basis,it provided references for further studies on the interaction between selenium and cadmium,and provided basis for establishing selenium-enriched barrier technology for crops.

Headspace Solid-Phase Micro-Extraction Gas Chromatography/Mass Spectrometry(HS-SPME-GC/MS)-Based Untargeted Metabolomics Analysis for Comparing the Volatile Components from 12 Panax Herbal Medicines

Quality control of ginseng currently is mainly based on ginsenoside analysis,but rarely focuses on the volatile organic components.In the current work,an untargeted metabolomics approach,by headspace solid-phase micro-extraction gas chromatography/mass spectrometry(HS-SPME-GC/MS),was elaborated and further employed to holistically compare the compositional difference of the volatile components simultaneously from 12 Panax herbal medicines,which included P.ginseng(PG),P.quinquefolius(PQ),P.notoginseng(PN),red ginseng(PGR),P.ginseng leaf(PGL),P.quinquefolius leaf(PQL),P.notoginseng leaf(PNL),P.ginseng flower(PGF),P.quinquefolius flower(PQF),P.notoginseng flower(PNF),P.japonicus(PJ),and P.japonicus var.major(PJvm).Chromatographic separation was performed on an HP-5MS elastic quartz capillary column using helium as the carrier gas,enabling good resolution within 1 h.We were able to characterize totally 259 volatile compounds,including 82 terpenes(T),46 alcohols(Alc),29 ketones(K),25 aldehydes(Ald),21 esters(E),and the others.By analyzing 90 batches of ginseng samples based on the untargeted metabolomics workflows,236 differential ions were unveiled,and accordingly 36 differential volatile components were discovered.It is the first report that simultaneously compares the compositional difference of volatile components among 12 Panax herbal medicines,and useful information is provided for the quality control of ginseng aside from the well-known ginsenosides.

The ecological response of natural phytoplankton population and related metabolic rates to future ocean acidification

Ocean acidifi cation(OA)and global warming-induced water column stratification can signifi cantly alter phytoplankton-related biological activity in the marine ecosystem.Yet how these changes may play out in the tropical Indian Ocean remains unclear.This study investigated the ecological and metabolic responses of the different phytoplankton functional groups to elevated CO_(2) partial pressure and nitrate deficiency in two different environments of the eastern Indian Ocean(EIO).It is revealed that phytoplankton growth and metabolic rates are more sensitive to inorganic nutrients rather than CO_(2).The combined interactive effects of OA and N-limitation on phytoplankton populations are functional groupspecific.In particular,the abundance and calcification rate of calcifying coccolithophores are expected to be enhanced in the future EIO.The underlying mechanisms for this enhancement may be ascribed to coccolithophore’s lower carbon concentrating mechanisms(CCMs)efficiency and OA-induced[HCO^(-)_(3)]increase.In comparison,the abundance of non-calcifying microphytoplankton(e.g.,diatoms and dinoflagellates)and primary productivity would be inhibited under those conditions.Diff erent from previous laboratory experiments,interspecifi c competition for resources would be an important consideration in the natural phytoplankton populations.These combined factors would roughly determine calcifying coccolithophores as“winners”and non-calcifying microphytoplankton as“losers”in the future ocean scenario.Due to the large species-specific differences in phytoplankton sensitivity to OA,comprehensive investigations on oceanic phytoplankton communities are essential to precisely predict phytoplankton ecophysiological response to ocean acidification.

Robust boron nanoplatform provokes potent tumoricidal activities via inhibiting heat shock protein

Near-infrared(NIR)-light-triggered photothermal therapy(PTT)is a promising treatment for breast cancer.However,its therapeutic efficiency is often compromised due to the heatinduced up-regulation of heat shock proteins,which confer photothermal resistance.To solve this urgent problem,PEGylated two-dimensional boron nanosheets(B-PEG)-which allow both multimodal imaging and photothermal conversion-were loaded with gambogic acid(GA),which can inhibit heat shock protein 90(Hsp90).Experimental findings indicated that this combination of B-PEG and GA could serve as an integrated drug delivery system for cancer diagnosis and treatment.It could be used to administer mild PTT as well as chemotherapy for breast cancer,provide improved anti-tumor effects,and reduce the toxicity of PTT,all while inhibiting breast cancer growth.This drug delivery system could offer a novel tool for administering chemotherapy combined with PTT while avoiding the adverse effects of traditional PTT.

Effects of Several Passivating Agents on Improvement of Cd Polluted Soil

Clay minerals,phosphates,alkaline materials,organic materials are common improvers in the management of Cd polluted soil. This paper systematically summarized types of common soil improvers and their passivation mechanism of Cd in soil. It reviewed advances in researches of soil improvers. Besides,it introduced major problems in four common passivating agents for management of Cd polluted soil. Finally,according to different mechanism characteristics of passivating agents,it came up with some recommendations.

Research on Improving the Effectiveness of College Students'Theme Education Practice in the New Media Era

Carrying out theme education practice is an important measure of Ideological and political work.The goal and content of theme education activities are generally overlapped with other activities,which makes the school unable to bear the burden of carrying out multiple activities at the same time,thus affecting the actual effect of theme education practice activities.In this paper,by improving the method of theme education,and with a positive attitude and innovative spirit to continue to innovate the working mode of theme education practice,the way of using new media technology in the process of theme education is analyzed,and its characteristics and laws are analyzed,so as to improve the effective working path of theme education.

基于顶空进样气相色谱-质谱联用和非靶标代谢组学分析人参、西洋参和三七经蒸制后挥发性成分的转化

人参是全世界范围内广受欢迎的滋补品,经蒸制后补益效果更佳。先前对人参蒸制的研究主要集中在所含的皂苷,但对其挥发性成分研究较少。本研究建立了顶空进样气相色谱-质谱联用结合非靶标代谢组学方法,对人参、西洋参和三七在蒸制过程中挥发性成分的变化进行整体性表征。通过优化GC-MS色谱分离条件,采用HP-5MS弹性石英毛细管柱在38分钟内实现对人参、西洋参和三七生品及蒸制品(1-10 h)中挥发性成分的表征。从人参、西洋参和三七中分别鉴定出了106、106和105种挥发性成分。多元统计分析可以描述不同蒸制时间介导的人参、西洋参和三七的转化轨迹。最终,通过基于GC-MS的非靶标代谢组学分析,发现人参、西洋参和三七蒸制过程中分别有13、16和14种差异成分。值得注意的是,其中异戊醇、2-正戊基呋喃、正己醛、丁香烯和(-)-马兜铃烯可以区分人参的生品和炮制品;α-蒎烯、2-正戊基呋喃、己酸、2,3-丁二醇和丙酮酸可以区分西洋参生品和炮制品;莎草烯、糠醛、Δ-杜松烯、羟基丙酮和1-戊醇可以区分三七生品和炮制品。本研究所建立的气相色谱-质谱联用方法可以揭示中药中挥发性成分的变化,为进一步探讨中药炮制机理提供一种实用的分析工具。

Fabricating pyridinic N-B sites in porous carbon as efficient metal-free electrocatalyst in conversion CO_(2)into CH_(4)

Electrochemical reduction of CO_(2)(CO_(2)RR)to value-added chemicals is an attractive strategy for greenhouse gas mitigation and carbon recycle.Carbon material is one of most promising electrocatalysts but its product selectivity is limited by few modulating approaches for active sites.Herein,the predominant pyridinic N-B sites(accounting for 80%to all N species)are fabricated in hierarchically porous structure of graphene nanoribbons/amorphous carbon.The graphene nanoribbons and porous structure can accelerate electron and ion/gas transport during CO_(2)RR,respectively.This carbon electrocatalyst exhibits excellent selectivity toward CO_(2)reduction to CH_(4)with the faradaic efficiency of 68%at−0.50 V vs.RHE.As demonstrated by density functional theory,a proper adsorbed energy of∗CO and∗CH_(2)O are generated on the pyridinic N-B site resulting into high CH_(4)selectivity.Therefore,this study provides a novel method to modulate active sites of carbon-based electrocatalyst to obtain high CH_(4)selectivity.

Enhancing phytolith carbon sequestration in rice ecosystems through basalt powder amendment

Global warming as a result of rapid increase in atmospheric COa emission is significantly influencing world＇s economy and human activities. Carbon sequestra- tion in phytoliths is regarded as a highly stable carbon sink mechanism in terrestrial ecosystems to mitigate climate change. However, the response of plant phytolith-occluded carbon （PhytOC） to external silicon amendments remains unclear. In this study, we investigated the effects of basalt powder （BP） amendment on phytolith carbon sequestration in rice （Oryza sativa）, a high-PhytOC accumulator. The results showed that the contents of phytolith and PhytOC in rice increased with BP amendment. The PhytOC produc- tion flux in different rice plant parts varied considerably （0.005-0.041 Mg CO_2 ha^-1 a^-1）, with the highest flux in the sheath. BP amendment can significantly enhance flux of phytolith carbon sequestration in croplands by 150 %. If the global rice cultivation of 1.55 × 10^8 ha had a similar flux of PhytOC production in this study, 0.61× 10^7 to 1.54 × 10^7 Mg CO_2 would be occluded annually within global rice phytoliths. These findings highlight that exter- nal silicon amendment such as BP amendment represents an effective potential management tool to increase long- term biogeochemical carbon sequestration in crops such as rice and may also be an efficient way to mitigate the global warming indirectly.

Effects of drying process of Yuanzhi (Radix Palygalae) on its bioactive ingredients

OBJECTIVE： To study the effects of the drying processing in terms operational parameters on the bio- active constituents of six YuanzhJ （Radix Palygalae） samples across China. METHODS： Six Yuanzhi （Radix Palygalae） samples were investigated using thermogravimetry analysis. The heating courses were set in two ways： the temperature-programmed process from room temperature to 150℃ ,and the constant-temperature course at 50℃, 70℃ and 90℃. RESULTS： The peak temperature of six Yuanzhi （Radix Palygalae） samples ranged from 78℃ to 88℃. The mass loss rate of Yuanzhi （Radix Palygalae） alcohol-soluble extract was significantly increased when heated at 90℃. Four types of bioactive ingredients were detected in volatile oils of Yuanzhi （Radix Palygalae） sample from Shanxi province by Gas Chromatography-mass spectrometry analysis. Fourier Transform Infrared Spectroscopy results showed that the drying temperature exerted a great influence on types and amount of ingredients of Yuanzhi （Radix Palygalae）. The kinetic study showed that the constant-temperature drying process of Yuanzhi Radix Palygalae） samples could be well de- scribed by the Page Model, especially for the drying process at 50~C, in which R2 and SD values were more than 0.98 and less than 0.04, respectively.The drying constant k of three Yuanzhi （Radix Palygalae） samples from Shanxi, Gansu and Shaanxi provinces in China was corresponding to the Arrhenius equation, and their activation energies were 28.07, 2.5.38 and 21.48 kJ/mol, respectively. CONCLUSION： The drying process of Yuanzhi （Radix Palygalae） was very important for bioactive ingredients improvement in Yuanzhi （Radix Palygalae）. Temperature was a thermodynamic property significantly affecting the process.

Isolation and Growth Characteristics of SARS-CoV-2 in Vero Cell

Dear Editors,The coronavirus disease 2019(COVID-19),caused by SARS-CoV-2,broke out in early December 2019 has escalated into a global pandemic(Lai et al.2020).Till the May 20 th 2020,more than 4,700,000 people were infected and the number is still increasing especially in Europe,North America and Asia(https://covid19.who.int/).

Zero-Shot Medical Image Retrieval for Emerging Infectious Diseases Based on Meta-Transfer Learning--Worldwide,2020

Introduction:Due to the increasing number of medical images,image retrieval has become an important technique for medical image analytics.Although many content-based image retrieval methods have been proposed,the retrieval of images in datasets related to emerging/new infectious diseases still remain a challenge-mostly due to the lack of historical data.As a result,the current retrieval models have limited functionality in helping doctors make accurate diagnoses of new diseases.Methods:In this paper,we propose a zero-shot retrieval model based on meta-learning and ensemble learning,which can obtain a model with stronger generalizability without using any relevant training data,and thus performs well on new types of test data.Results:The experimental results showed that the proposed method is 3% to 5% higher than the traditional method,which means that our model can retrieve relevant medical images more accurately for newly emerging data types and provide doctors with more effective assistance.Discussion:When a new infectious disease occurs,doctors can use the proposed zero-shot retrieval model to retrieve all relevant cases,quickly find the common problems of patients,find the locations of the new infections,and determine its infectivity as soon as possible.The proposed method is a new computeraided decision support technology for emerging infectious diseases.