Understanding the Reversible Reactions of Li-N_(2) Battery Catalyzed With SnO_(2)

Metal–N_(2) battery can be applied in both energy storage and electrochemical nitrogen reduction reaction(NRR);however,there has been only extraordinarily little study on metal–N_(2) battery since its electrochemical reversibility still needs further proofs.And its electrochemical performances also need to be enhanced.Herein,we investigated the discharge–charge reactions between Li anode and N_(2) cathode via designing an efficient catalyst of nanosized SnO_(2) particles dispersed on N-doped carbon nanosheets(SnO 2@NC)for the Li-N_(2) battery,with good cyclic stability and a high specific capacity of 0.25 mA h(~500 mA h g^(−1))at a large current density of 1000 mA g^(−1).The electrochemical reversibility of both NRR in the discharge process and nitrogen extraction reaction in the charge process for Li-N 2 battery is discussed.Time-of-flight secondary ion mass spectrometry results imply that the SnO_(2)@NC can effectively promote the adsorption of N_(2) and the activation of NRR in the discharge process.Furthermore,ex situ X-ray photoelectron spectroscopy and Fourier transform infrared tests are performed to study the electrochemical reversibility of Li-N_(2) battery.It can be proved that the formation and decomposition of discharging product Li_(3)N are electrochemical reversible during cycling in our deigned Li-N_(2) battery system with SnO_(2)@NC catalyst.

Genome assembly of Polygala tenuifolia provides insights into its karyotype evolution and triterpenoid saponin biosynthesis

Polygala tenuifolia is a perennial medicinal plant that has been widely used in traditional Chinese medicine for treating mental diseases.However,the lack of genomic resources limits the insight into its evolutionary and biological characterization.In the present work,we reported the P.tenuifolia genome,the first genome assembly of the Polygalaceae family.We sequenced and assembled this genome by a combination of Illumnina,PacBio HiFi,and Hi-C mapping.The assembly includes 19 pseudochromosomes covering∼92.68%of the assembled genome(∼769.62 Mb).There are 36463 protein-coding genes annotated in this genome.Detailed comparative genome anal-ysis revealed that P.tenuifolia experienced two rounds of whole genome duplication that occurred∼39–44 and∼18–20 million years ago,respectively.Accordingly,we systematically reconstructed ancestral chromosomes of P.tenuifolia and inferred its chromosome evolution trajectories from the common ancestor of core eudicots to the present species.Based on the transcriptomics data,enzyme genes and transcription factors involved in the synthesis of triterpenoid saponin in P.tenuifolia were identified.Further analysis demonstrated that whole-genome duplications and tandem duplications play critical roles in the expansion of P450 and UGT gene families,which contributed to the synthesis of triterpenoid saponins.The genome and transcriptome data will not only provide valuable resources for comparative and functional genomic researches on Polygalaceae,but also shed light on the synthesis of triterpenoid saponin.

CNT@MnO_(2) composite ink toward a flexible 3D printed micro-zinc-ion battery

Flexible energy storage devices have played a significant role in multiscenario applications,while flexible zinc-ion batteries(ZIBs),as an essential branch,have developed rapidly in recent years.Three-dimensional(3D)printing is an extremely advanced technology to design and modify the structure of batteries and provides unlimited possibilities for the diversified development of energy storage equipment.Herein,by utilizing 3D printing technology,carbon nanotube(CNT)is coated by MnO_(2) to form a flexible CNT@MnO_(2) ink as a cathode for flexible aqueous micro-ZIBs for the first time and zinc powder ink is used as an anode due to its high flexibility and bendability.The Zn//CNT@MnO_(2) flexible battery shows a stable capacity of 63μAh cm^(−2) at 0.4mA cm^(−2).When the battery is bent in different states,the maximum capacity loss compared with the initial value is only 2.72%,indicating its stability.This study shows the potential of 3D printing technology in the development of flexible manganese-based ZIBs.

Plasma assisted synthesis of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2) cathode materials with good cyclic stability at subzero temperatures

Layered Ni-rich cathode materials,LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622),are synthesized via solid reaction assisted with a plasma milling pretreatment,which is resulted in lowering sintering temperatures for solid precursors.The plasma milling pretreated NCM622 cathode material sintered at 780℃(named as PM-780)demonstrates good cycling stability at both room and subzero temperatures.Specifically,the PM-780 cathode delivers an initial discharge capacity of 171.2 mAh g^(-1) and a high capacity retention of 99.7%after 300 cycles with current rate of 90 mA g^(-1) at 30℃,while stable capacities of 120.3 and 94.0 m Ah g^(-1) can be remained at-10℃and-20℃in propylene carbonate contained electrolyte,respectively.In-situ XRD together with XPS and SEM reveal that the NCM622 cycled at-10℃presented better structural stability and more intact interface than that of cathodes cycled at 30℃.It is also found that subzero temperatures only limit the discharge potential of NCM622 without destroying its structure during cycling since it still exhibits high discharge capacity at 30℃after cycled at subzero temperatures.This work may expand the knowledge about the low-temperature characteristics of layered cathode materials for Li-ion batteries and lay the foundation for its further applications.

Late Jurassic adakitic ore-bearing granodiorite porphyry intrusions in the Xiaokele porphyry Cu(–Mo)deposit,Northeast China:implications for petrogenesis and tectonic setting

The Xiaokele Cu(–Mo)deposit is a recently discovered porphyry deposit in the northern Great Xing’an Range(GXR)of northeast China.The ore bodies in this deposit are mainly hosted within granodiorite porphyry intrusions.Potassic,phyllic,and propylitic alteration zones develop from center to edge.In this paper,we present zircon LA–ICP–MS U–Pb ages,zircon Hf isotopic compositions,and whole-rock geochemistry of the ore-bearing granodiorite porphyries from the Xiaokele Cu(–Mo)deposit.Zircon U–Pb dating suggests that the Xiaokele granodiorite porphyries were emplaced at 148.8±1.1 Ma(weighted-mean age;n=14).The Xiaokele granodiorite porphyries display high SiO2,Al2O3,Sr,and Sr/Y,low K2O/Na2O,MgO,Yb,and Y,belonging to high-SiO2 adakites produced by partial melting of the subducted oceanic slab.Marine sediments were involved in the magma source of the Xiaokele granodiorite porphyries,as indicated by enriched Sr–Nd isotopic compositions(eNd(-t)=-1.17–-0.27),low positive zircon eHf(t)values(0.4–2.2),and high Th contents(4.06–5.20).The adakitic magma subsequently interacted with the mantle peridotites during ascent through the mantle wedge.The Xiaokele granodiorite porphyries were derived from slab melting during the southward subduction of the Mongol–Okhotsk Ocean.

Improved diagnosis of thyroid cancer aided with deep learning applied to sonographic text reports:a retrospective,multi-cohort,diagnostic study

Objective:Large volume radiological text data have been accumulated since the incorporation of electronic health record(EHR)systems in clinical practice.We aimed to determine whether deep natural language processing algorithms could aid radiologists in improving thyroid cancer diagnosis.Methods:Sonographic EHR data were obtained from the EHR database.Pathological reports were used as the gold standard for diagnosing thyroid cancer.We developed thyroid cancer diagnosis based on natural language processing(THCaDxNLP)to interpret unstructured sonographic text reports for thyroid cancer diagnosis.We used the area under the receiver operating characteristic curve(AUROC)as the primary metric to measure the performance of the THCaDxNLP.We compared the performance of thyroid ultrasound radiologists aided with THCaDxNLP vs.those without THCaDxNLP using 5 independent test sets.Results:We obtained a total number of 788,129 sonographic radiological reports.The number of thyroid sonographic data points was 132,277,18,400 of which were thyroid cancer patients.Among the 5 test sets,the numbers of patients per set were 439,186,82,343,and 171.THCaDxNLP achieved high performance in identifying thyroid cancer patients(the AUROC ranged from 0.857–0.932).Thyroid ultrasound radiologists aided with THCaDxNLP achieved significantly higher performances than those without THCaDxNLP in terms of accuracy(93.8%vs.87.2%;one-sided t-test,adjusted P=0.003),precision(92.5%vs.86.0%;P=0.018),and F1 metric(94.2%vs.86.4%;P=0.007).Conclusions:THCaDxNLP achieved a high AUROC for the identification of thyroid cancer,and improved the accuracy,sensitivity,and precision of thyroid ultrasound radiologists.This warrants further investigation of THCaDxNLP in prospective clinical trials.

Radio-frequency system of the high energy photon source

Purpose High energy photon source is a 6 GeV diffraction-limited storage ring light source currently under construction in Beijing.A low-frequency fundamental radio-frequency(rf)system of 166.6 MHz was proposed to accommodate the accelerator physics design.Superconducting rf(srf)technologies were chosen for the storage ring rf accompanied by solid-state power amplifiers and digital low-level rf controls.The design of the rf system was completed,and the parameters are frozen.Elucidation of the rf design with key parameters is desired.Methods The requirements from the accelerator physics design will be presented followed by the detailed rf design.The logic behind the choice of key rf parameters is elaborated.The configuration of the entire rf system is presented.Results and conclusions The fundamental srf cavity of 166.6 MHz was designed to accelerate the ultrarelativistic electron beam.Heavy damping of higher-order modes in these cavities is required to avoid the coupled bunch instabilities.An active third harmonic srf of 499.8 MHz was adopted to realize the required rf gymnastics.Normal-conducting 5-cell cavities will be used for the booster rf.Solid-state amplifiers of 2.4 MW in total will be installed at HEPS to drive these cavities in the booster and the storage ring.A digital low-level rf system will be used to regulate rf field inside each cavity with high stabilities.The rf configuration during the commissioning and the operation scenarios are also presented.

Sequencing of Cultivated Peanut, Arachis hypogaea, Yields Insights into Genome Evolution and Oil Improvement

Cultivated peanut (Arachis hypogaea) is an allotetraploid crop planted in Asia, Africa, and America for edible oil and protein. To explore the origins and consequences of tetraploidy, we sequenced the allotetraploid A. hypogaea genome and compared it with the related diploid Arachis duranensis and Arachis ipaensis genomes. We annotated 39 888 A-subgenome genes and 41 526 B-subgenome genes in allotetraploid peanut. The A. hypogaea subgenomes have evolved asymmetrically, with the B subgenome resembling the ancestral state and the A subgenome undergoing more gene disruption, loss, conversion, and transposable element proliferation, and having reduced gene expression during seed development despite lacking genome-wide expression dominance. Genomic and transcriptomic analyses identified more than 2 500 oil metabolism-related genes and revealed that most of them show altered expression early in seed development while their expression ceases during desiccation, presenting a comprehensive map of peanut lipid biosynthesis. The availability of these genomic resources will facilitate a better understanding of the complex genome architecture, agronomically and economically important genes, and genetic improvement of peanut.

Fluorescence correlation spectroscopy in laser gradient field

Fluorescence correlation spectroscopy (FCS) is capable of probing dynamic processes in living biological systems. From photon fluctuation of fluorescing particles which diffuse through a small detection volume, FCS reveals information on the concentration and the structure of the particles, as well as information on microscopic environment. In this note, we study the radiation forces experienced by Rayleigh particles in a laser field in details, and analyze the effects of gradient field on FCS measurements.

Development of a 500-MHz waveguide directional coupler with high directivity for HEPS

Purpose In order to achieve a high-precision measurement of the incident and the reflected power,a WR1800 rectangular waveguide directional coupler with high directivity and high power level has been in-house developed.Multiple couplers will be installed in the 500-MHz high-power radio-frequency transmission lines delivering 200-kW continuous-wave power for the High Energy Photon Source(HEPS).Methods The directional coupler adopts the design scheme of primary and secondary transmission lines and coaxial coupling-head structure.The shape and dimensional parameters of the coupling head were carefully optimized by using microwave simulation codes.An optimum directivity of 64 dB was achieved in simulations.Results and conclusions A prototype coupler was subsequently manufactured,and its directivity was measured to be 48.2 dB following a rigorous calibration procedure,largely exceeding the design goal and the commercial product.The coupler was then connected to an existing 500-MHz klystron system,and a high-power test with short-circuit termination was conducted.The high directivity of the coupler was confirmed up to 200 kW.During the 6 hours of power aging with continuous-wave 200 kW in a standing-wave setup,no performance degradation was observed on the coupler.The coupler temperature was measured to be 20◦C above the ambient environment.The design requirements were comfortably fulfilled.These constitute thefirst in-house development of a large-size waveguide directional coupler with high directivity and high power level for HEPS.The design,fabrication,and performance tests of the directional coupler are presented.

Paleo-polyploidization in Lycophytes

Lycophytes and seed plants constitute the typical vascular plants.Lycophytes have been thought to have no paleo-polyploidization although the event is known to be critical for the fast expansion of seed plants.Here,genomic analyses including the homologous gene dot plot analysis detected multiple paleo-polyploidization events,with one occurring approximately 13–15 million years ago(MYA)and another about 125–142 MYA,during the evolution of the genome of Selaginella moellendorffii,a model lycophyte.In addition,comparative analysis of reconstructed ancestral genomes of lycophytes and angiosperms suggested that lycophytes were affected by more paleopolyploidization events than seed plants.Results from the present genomic analyses indicate that paleo-polyploidization has contributed to the successful establishment of both lineages—lycophytes and seed plants—of vascular plants.

HOM damping requirements and measurements for CEPC 650-MHz 2-cell cavity

Introduction The circular electron-positron collider(CEPC)will use a 650-MHz RF system with 240 two-cell cavities for the collider.The collider is a double ring with shared cavities for Higgs operation and separate cavities for W and Z operations.The higher-order modes(HOM)excited by the intense beam bunches must be damped to avoid additional cryogenic loss and multi-bunch instabilities.Materials and methods To get the real damping results,two prototypes of HOM coupler have been fabricated and installed on the 650-MHz two-cell cavity.The HOMs have been verified by bead pulling method.A test bench with two 2-cell cavities is used to measure the real damping results and study HOM propagating properties for a cavity string.Conclusion In this paper,the impedance budget,HOM damping and HOM power requirements for the CEPC collider ring are given.The damping results measured for the fundamental mode and HOMs seem good compared with the simulated results.The absorbing efficiency of the absorber and the extraction power efficiency of HOM couplers were also achieved.

HOM coupler design for 166.6MHz SC cavity

Purpose Higher-order modes(HOMs)may affect beam stability and refrigeration requirements of superconducting cavity such as the 166.6MHz SC cavity,which is studied at IHEP.Under certain conditions,beam-induced HOMs can accumulate sufficient energy to destabilize the beam or quench the superconducting cavities.Methods In order to limit these effects,we consider the use of the HOM coupler with HOMs extraction on the cutoff tubes of the 166.6MHz SC cavity.Results The HOM coupler can deeply suppress the fundamental mode and efficiently extract dangerous high-order modes.Conclusions In this paper,the HOM coupler design process is presented,which operates at 166.6MHz.The RF and thermal behavior are discussed.In order to verify the designs,a rapid prototype for the favored couplerwas fabricated and characterized on a low-power test stand.

A higher-order mode coupler design for HEPS 166.6 MHz superconducting accelerating cavities

Purpose The 166.6 MHz superconducting radio frequency cavities have been proposed for High Energy Photon Source(HEPS)storage ring.HEPS is a 6 GeV,200 mA diffraction-limited synchrotron light source to be built in Beijing.Higherorder modes(HOMs)excited in 166.6 MHz SRF cavities have to be sufficiently damped in order to prevent coupled-bunch instabilities and to limit parasitic mode losses.Methods A hybrid HOM damping scheme has been proposed.An enlarged beam pipe allows HOMs above beam pipe cutoff frequencies to propagate and subsequently be absorbed by dampers installed on the downstream beam pipe,while a petal-shaped coaxial structure extracts HOMs below beam pipe cutoff frequencies and subsequently damped by the specially designed coaxial filter.Results HOMdamping in cavities has been demonstrated by 3D simulations.The impedance of HOMs has been successfully reduced to be lower than the coupled-bunch instability threshold.In addition,no hard barrier multipaction has been observed and acceptable heat loss is obtained.Conclusions In this paper,the hybrid HOM damping scheme has been demonstrated.Based on these studies,a prototype petal–loop structure and its associated filter are being fabricated.