新时期高校实验技术队伍建设的实践与探索

化学基础国家级实验教学示范中心(北京大学)始终鼓励实验技术人员在完成教学支撑工作的基础上,结合个人专业特长和兴趣爱好参与其他工作。本文主要介绍了近年来技术人员在参与实验教学及教学改革、教学仪器研制与改进、实验室建设及社会服务等方面的具体做法,通过调动实验技术人员的主观能动性,释放个人创新潜能,促进技术人员素质的全面提升和个性化发展。

化学“101计划”——化学生物学实验课程的建设

介绍了化学“101计划”核心课程之一“化学生物学实验”的建设情况。针对化学生物学学科的交叉特色、实验课程在学科研究中的重要作用和化学“101计划”的建设目标,本文分别从课程建设思路、教材内容及编写特色等方面进行了梳理和总结。

Genetic and biological properties of H9N2 avian influenza viruses isolated in central China from2020 to 2022

The H9N2 subtype of avian influenza virus(AIV)is widely prevalent in poultry and wild birds globally,and has become the predominant subtype circulating in poultry in China.The H9N2 AIV can directly or indirectly(by serving as a"donor virus")infect humans,posing a significant threat to public health.Currently,there is a lack of in-depth research on the prevalence of H9N2 viruses in Shanxi Province,central China.In this study,we isolated 14 H9N2 AIVs from October 2020 to April 2022 in Shanxi Province,and genetic analysis revealed that these viruses belonged to 7 different genotypes.Our study on animals revealed that the H9N2 strains we identified displayed high transmission efficiency among chicken populations,and exhibited diverse replication abilities within these birds.These viruses could replicate efficiently in the lungs of mice,with one strain also demonstrating the capacity to reproduce in organs like the brain and kidneys.At the cellular level,the replication ability of different H9N2 strains was evaluated using plaque formation assays and multi-step growth curve assays,revealing significant differences in the replication and proliferation efficiency of the various H9N2 viruses at the cellular level.The antigenicity analysis suggested that these isolates could be classified into 2 separate antigenic clusters.Our research provides crucial data to help understand the prevalence and biological characteristics of H9N2 AIVs in central China.It also highlights the necessity of enhancing the surveillance of H9N2 AIVs.

Analysis of vascular thrombus and clinicopathological factors in prognosis of gastric cancer:A retrospective cohort study

BACKGROUND Gastric cancer(GC)is one of the most common malignant tumors in the world,and its prognosis is closely related to many factors.In recent years,the incidence of vascular thrombosis in patients with GC has gradually attracted increasing attention,and studies have shown that it may have a significant impact on the survival rate and prognosis of patients.However,the specific mechanism underlying the association between vascular thrombosis and the prognosis of patients with GC remains unclear.AIM To analyze the relationships between vascular cancer support and other clinicopathological factors and their influence on the prognosis of patients with GC.METHODS This study retrospectively analyzed the clinicopathological data of 621 patients with GC and divided them into a positive group and a negative group according to the presence or absence of a vascular thrombus.The difference in the 5-year cumulative survival rate between the two groups was compared,and the relationships between vascular cancer thrombus and other clinicopathological factors and their influence on the prognosis of patients with GC were analyzed.RESULTS Among 621 patients with GC,the incidence of vascular thrombi was 31.7%(197 patients).Binary logistic regression analysis revealed that the degree of tumor differentiation,depth of invasion,and extent of lymph node metastasis were independent influencing factors for the occurrence of vascular thrombi in GC patients(P<0.01).The trend of the χ^(2) test showed that the degree of differentiation,depth of invasion,and extent of lymph node metastasis were linearly correlated with the percentage of vascular thrombi in GC patients(P<0.01),and the correlation between lymph node metastasis and vascular thrombi was more significant(r=0.387).Univariate analysis revealed that the 5-year cumulative survival rate of the positive group was significantly lower than that of the negative group(46.7%vs 73.3%,P<0.01).Multivariate analysis revealed that age,tumor diameter,TNM stage,and vascular thrombus were independent risk factors for the prognosis of GC patients(all P<0.05).Further stratified analysis revealed that the 5-year cumulative survival rate of stage Ⅲ GC patients in the thrombolase-positive group was significantly lower than that in the thrombolase-negative group(36.1%vs 51.4%;P<0.05).CONCLUSION Vascular cancer status is an independent risk factor affecting the prognosis of patients with GC.The combination of vascular cancer suppositories and TNM staging can better judge the prognosis of patients with GC and guide more reasonable treatment.

打造教师教学发展共同体,多校共上一堂课——“大学化学实验课程群虚拟教研室”教研活动初探及成效

介绍“大学化学实验课程群虚拟教研室”在创新教研形态、加强教学研究、共建优质资源以及开展教师培训等方面开展的一系列工作及取得的初步实效。重点阐明了“多校共上一堂课,共享教学云资源”的示范教学直播课活动的教研形式以及教学内容的选取原则。

The Influence of Centrifugal Force on the Interference Fit of High-Speed Electric Spindle

The letter presents an analysis of interference fit of the electric spindle at different rotor speeds due to the influence of centrifugal force and provides a theoretical formula showing the relationship of the speed, stress on the rotation speed. The letter also established a finite element model of the interference fit. The study found that as the rotation speed increases, the interference and contact stress between the spindle and the rotor gradually decrease, and the reduced speed is proportional to the square of the rotation speed.

适应创新性人才培养的仪器分析实验教学改革初探

为适应创新性人才培养,本文介绍了北京大学化学与分子工程学院仪器分析实验教学团队所进行的教学改革初步探索,包括采用线上线下相结合的学习模式;增加实际样品测试;采取小班教学模式;对同一样品采用多种分析方法进行对比测试等。这些改革措施的实施,显著提高了课程质量和教学效果。

Numerical Study of a Novel Procedure for Installing the Tower and Rotor Nacelle Assembly of Offshore Wind Turbines Based on the Inverted Pendulum Principle

Current installation costs of offshore wind turbines(OWTs) are high and profit margins in the offshore wind energy sector are low, it is thus necessary to develop installation methods that are more efficient and practical. This paper presents a numerical study(based on a global response analysis of marine operations) of a novel procedure for installing the tower and Rotor Nacelle Assemblies(RNAs) on bottom-fixed foundations of OWTs. The installation procedure is based on the inverted pendulum principle. A cargo barge is used to transport the OWT assembly in a horizontal position to the site, and a medium-size Heavy Lift Vessel(HLV) is then employed to lift and up-end the OWT assembly using a special upending frame. The main advantage of this novel procedure is that the need for a huge HLV(in terms of lifting height and capacity) is eliminated. This novel method requires that the cargo barge is in the leeward side of the HLV(which can be positioned with the best heading) during the entire installation. This is to benefit from shielding effects of the HLV on the motions of the cargo barge, so the foundations need to be installed with a specific heading based on wave direction statistics of the site and a typical installation season. Following a systematic approach based on numerical simulations of actual operations, potential critical installation activities, corresponding critical events, and limiting(response) parameters are identified. In addition, operational limits for some of the limiting parameters are established in terms of allowable limits of sea states. Following a preliminary assessment of these operational limits, the duration of the entire operation, the equipment used, and weather-and water depth-sensitivity, this novel procedure is demonstrated to be viable.

Artemlavanins A and B from Artemisia lavandulaefolia and Their Cytotoxicity Against Hepatic Stellate Cell Line LX2

Two new sesquiterpenoids,artemlavanins A(1)and B(3),together with fifteen known compounds(2 and 4−17)were iso-lated from the EtOH extract of Artemisia lavandulaefolia.The structures of new compounds were elucidated by extensive spectroscopic analyses(HRESIMS,1D and 2D NMR)and ECD calculations.Compound 1 was a sesquiterpenoid lactone possessing a rearranged eudesmane skeleton;compounds 2-5,6-8,9 and 10-12 belonged to the eudesmane,guaiane,oppositane and farnesane sesquiterpenoids,respectively;compounds 13-17 were the phenyl derivatives with a 4-hydroxy-acetophenone moiety.Twelve compounds(1-3,5-7,10-12,14,15 and 17)displayed cytotoxicity against hepatic stellate cell line LX2(HSC-LX2)with IC50 values ranging from 35.1 to 370.3μM.Compounds 2,7,10-12 and 17 exhibited the stronger cytotoxicity than silybin(IC50,169.6μM)with IC50 values of 82.1,35.1,95.0,83.8,81.6 and 90.1μM.Compound 7 as the most active one showed significant inhibition on the deposition of human collagen type I(Col I),human hyaluronic acid(HA)and human laminin(HL)with IC50 values of 10.7,24.5 and 13.3μM.

Fault Tolerant Design of Large-Scale Digital Beam Forming in SRAM-FPGAs for Software Defined Satellite Platforms

Large scale digital beamforming(LS-DBFs)are widely used in satellite communications for spectrum reuse and transmission enhancement.SRAM-FPGAs are a popular option for software defined satellite platforms due to their rich computation resources and high flexibility.However,they are sensitive to soft errors,which limit their application in space.This paper discusses the application of coding based fault tolerance schemes for the protection of LS-DBFs on software defined payloads.Since multiple FPGAs are usually needed to support the whole LS-DBFs system,different decomposition schemes are compared in terms of resource efficiency and reliability when the coding based scheme is applied to protect the DBFs on a FPGA.Theoretical analysis and hardware experiments shows that resource efficiency and reliability are a pair of contradictory requirements for decomposition schemes.The protection with vertical decomposition could improve the reliability by 96%with 1.5x redundancy.And the protection with horizontal decomposition could improve the reliability by 85%with 1.2 x redundancy.

Sulforaphane prevents LPS‑induced inflammation by regulating the Nrf2‑mediated autophagy pathway in goat mammary epithelial cells and a mouse model of mastitis

Background Mastitis not only deteriorates the composition or quality of milk,but also damages the health and pro-ductivity of dairy goats.Sulforaphane(SFN)is a phytochemical isothiocyanate compound with various pharmacologi-cal effects such as anti-oxidant and anti-inflammatory.However,the effect of SFN on mastitis has yet to be elucidated.This study aimed to explore the anti-oxidant and anti-inflammatory effects and potential molecular mechanisms of SFN in lipopolysaccharide(LPS)-induced primary goat mammary epithelial cells(GMECs)and a mouse model of mastitis.Results In vitro,SFN downregulated the mRNA expression of inflammatory factors(tumor necrosis factor-α(TNF-α),interleukin(IL)-1βand IL-6),inhibited the protein expression of inflammatory mediators(cyclooxygenase-2(COX2),and inducible nitric oxide synthase(iNOS))while suppressing nuclear factor kappa-B(NF-κB)activation in LPS-induced GMECs.Additionally,SFN exhibited an antioxidant effect by increasing Nrf2 expression and nuclear translocation,up-regulating antioxidant enzymes expression,and decreasing LPS-induced reactive oxygen species(ROS)produc-tion in GMECs.Furthermore,SFN pretreatment promoted the autophagy pathway,which was dependent on the increased Nrf2 level,and contributed significantly to the improved LPS-induced oxidative stress and inflammatory response.In vivo,SFN effectively alleviated histopathological lesions,suppressed the expression of inflammatory factors,enhanced immunohistochemistry staining of Nrf2,and amplified of LC3 puncta LPS-induced mastitis in mice.Mechanically,the in vitro and in vivo study showed that the anti-inflammatory and anti-oxidative stress effects of SFN were mediated by the Nrf2-mediated autophagy pathway in GMECs and a mouse model of mastitis.Conclusions These results indicate that the natural compound SFN has a preventive effect on LPS-induced inflam-mation through by regulating the Nrf2-mediated autophagy pathway in primary goat mammary epithelial cells and a mouse model of mastitis,which may improve prevention strategies for mastitis in dairy goats.

Bio-compatibility and cytotoxicity studies of water-soluble CuInS_2-ZnS-AFP fluorescence probe in liver cancer cells

BACKGROUND： The oncogenesis of hepatocellular carcinoma（HCC） is not clear. The current methods of the pertinent studies are not precise and sensitive. The present study was to use liver cancer cell line to explore the bio-compatibility and cytotoxicity of ternary quantum dots（QDs） probe and to evaluate the possible application of QDs in HCC.METHODS： CuInS_2-ZnS-AFP fluorescence probe was designed and synthesized to label the liver cancer cell HepG 2. The cytotoxicity of CuInS_2-ZnS-AFP probe was evaluated by MTT experiments and flow cytometry. RESULTS： The labeling experiments indicated that CuInS_2-ZnS QDs conjugated with AFP antibody could enter HepG 2 cells effectively and emit intensive yellow fluorescence by ultraviolet excitation without changing cellular morphology. Toxicity tests suggested that the cytotoxicity of CuInS_2-ZnS-AFP probe was significantly lower than that of CdT e-ZnS-AFP probe（t test, F=0.8, T=-69.326, P〈0.001）. For CuInS_2-ZnS-AFP probe, timeeffect relationship was presented in intermediate concentration（〉20%） groups（P〈0.05） and dose-effect relationship was presented in almost all of the groups（P〈0.05）. CONCLUSION： CuInS_2-ZnS-AFP QDs probe had better biocompatibility and lower cytotoxicity compared with CdT e-ZnS-AFP probe, and could be used for imaging the living cells in vitro.

Multi-Panel Extra-Large Scale MIMO Based Joint Activity Detection and Channel Estimation for Near-Field Massive IoT Access

The extra-large scale multiple-input multiple-output(XL-MIMO)for the beyond fifth/sixth generation mobile communications is a promising technology to provide Tbps data transmission and stable access service.However,the extremely large antenna array aperture arouses the channel near-field effect,resulting in the deteriorated data rate and other challenges in the practice communication systems.Meanwhile,multi-panel MIMO technology has attracted extensive attention due to its flexible configuration,low hardware cost,and wider coverage.By combining the XL-MIMO and multi-panel array structure,we construct multi-panel XL-MIMO and apply it to massive Internet of Things(IoT)access.First,we model the multi-panel XL-MIMO-based near-field channels for massive IoT access scenarios,where the electromagnetic waves corresponding to different panels have different angles of arrival/departure(AoAs/AoDs).Then,by exploiting the sparsity of the near-field massive IoT access channels,we formulate a compressed sensing based joint active user detection(AUD)and channel estimation(CE)problem which is solved by AMP-EM-MMV algorithm.The simulation results exhibit the superiority of the AMP-EM-MMV based joint AUD and CE scheme over the baseline algorithms.

Structural transformation of metal–organic framework with constructed tetravalent nickel sites for efficient water oxidation

A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction(OER)during the water oxidation process.In particular,Ni oxide incorporated with even a small amount of Fe leads to substantively enhanced OER activity.However,the critical role of Fe species during the electrocatalytic process is still under evaluation.Herein,we report nickel(oxy)hydroxide incorporated with Fe through the surface reconstruction of a bimetallic metal-organic framework(NiFe-MOF)during the water oxidation process.The spectroscopic investigations with theoretical calculations reveal the critical role of Fe in promoting the formation of highly oxidized Ni^(4+),which directly correlates with an enhanced OER activity.Both the geometric and electronic structu res of the as-reconstructed Ni_(1-x)Fe_(x)OOH electrocatalysts can be delicately tuned by the Ni-Fe ratio of the bimetallic NiFe-MOF,further affecting the catalytic activity.As a result,the Ni_(1-x)Fe_(x)OOH derived from Ni_(0.9)Fe_(0.1)-MOF delivers low overpotentials of 260 mV at 10 mA cm^(-2)and 400 mV at 300 mA cm^(-2).

Effects of Wind-Wave Misalignment on a Wind Turbine Blade Mating Process:Impact Velocities,Blade Root Damages and Structural Safety Assessment

Most wind turbine blades are assembled piece-by-piece onto the hub of a monopile-type offshore wind turbine using jack-up crane vessels.Despite the stable foundation of the lifting cranes,the mating process exhibits substantial relative responses amidst blade root and hub.These relative motions are combined effects of wave-induced monopile motions and wind-induced blade root motions,which can cause impact loads at the blade root’s guide pin in the course of alignment procedure.Environmental parameters including the wind-wave misalignments play an important role for the safety of the installation tasks and govern the impact scenarios.The present study investigates the effects of wind-wave misalignments on the blade root mating process on a monopile-type offshore wind turbine.The dynamic responses including the impact velocities between root and hub in selected wind-wave misalignment conditions are investigated using multibody simulations.Furthermore,based on a finite element study,different impact-induced failure modes at the blade root for sideways and head-on impact scenarios,developed due to wind-wave misalignment conditions,are investigated.Finally,based on extreme value analyses of critical responses,safe domain for the mating task under different wind-wave misalignments is compared.The results show that although misaligned wind-wave conditions develop substantial relative motions between root and hub,aligned wind-wave conditions induce largest impact velocities and develop critical failure modes at a relatively low threshold velocity of impact.

Artemyrianins A-G from Artemisia myriantha and Their Cytotoxicity Against HepG2 Cells

Four new sesquiterpenoids,artemyrianins A-D(1-4),and three new norlignans,artemyrianins E-G(5-7),together with five known compounds(8-12),were isolated from the aerial parts of Artemisia myriantha(Asteraceae).The new compounds were established by spectroscopic data analyses(HRMS,IR,1D and 2D NMR),and their absolute configurations were confirmed by the single-crystal X-ray diffraction or ECD calculations.The isolates showed cytotoxicity against HepG2 cells with IC50 values ranging from 33.3 to 145.2μM.

Blockchain Based Secure Relay Scheme for Space-Terrestrial Integrated Networks

The future 6G networks will integrates space and terrestrial networks to realize a fully connected world with extensive collaboration.However,how to build trust between multiple parties is a difficult problem for secure cooperation without a reliable third-party.Blockchain is a promising technology to solve this problem by converting the trust between multi-parties to the trust to the common shared data.Several works have proposed to apply the incentive mechanism in blockchain to encourage effective cooperation,but how to evaluate the cooperation performance and avoid breach of contract is not discussed.In this paper,a secure relay scheme is proposed based on the consortium blockchain system composed by different operators.In particular,smart contract checks the integrity of the message based on RSA accumulator,and executes transactions automatically when the message is delivered successfully.Detailed procedures are introduced for both uplink and downlink relay.Implementation based on Hyperledger Fabric proves the effectiveness of the proposed scheme and shows that the complexity of the scheme is low enough for practical deployment.

Radiation Tolerant Viterbi Decoders for On-Board Processing(OBP) in Satellite Communications

Modern satellite communication systems require on-board processing(OBP)for performance improvements,and SRAM-FPGAs are an attractive option for OBP implementation.However,SRAM-FPGAs are sensitive to radiation effects,among which single event upsets(SEUs)are important as they can lead to data corruption and system failure.This paper studies the fault tolerance capability of a SRAM-FPGA implemented Viterbi decoder to SEUs on the user memory.Analysis and fault injection experiments are conducted to verify that over 97%of the SEUs on user memory would not lead to output errors.To achieve a better reliability,selective protection schemes are then proposed to further improve the reliability of the decoder to SEUs on user memory with very small overhead.Although the results are obtained for a specific FPGA implementation,the developed reliability estimation model and the general conclusions still hold for other implementations.

Terminal-to-Terminal Calling for GEO Broadband Mobile Satellite Communication

Satellite and terrestrial components of IMT-Advanced need to be integrated so that the traditional strengths of each component can be fully exploited. LTE/LTE-A is now a recognized foundation of terrestrial 4G networks, and mobile satellite networks should be based on it. Long transmission delay is one of the main disadvantages of satellite communication, especially in a GEO system, and terminal-to-terminal （TtT） design reduces this delay. In this paper, we propose a protocol architecture based on LTE/LTE-A for GEO mobile satellite communication. We propose a detailed call procedure and four TtT modes for this architecture. We describe the division of tasks between the satellite gateway （SAT-GW） and satellite as well as TtT processing in the physical layer of the satellite in order to reduce delay and ensure compatibility with a terrestrial LTE/LTE-A system.

Comprehensive Strategy for Keloid Treatment:Experience at Shanghai Ninth People's Hospital

Keloids are a notorious fibroproliferative disorder that may cause cosmetic concerns and life inconvenience.Various methods such as surgery,injection,and laser have been used;however,single treatments are at risk of recurrence;therefore,comprehensive therapy is the better solution.Here,we focused on the management of different medical interventions according to subjective and objective conditions of keloid patients and summarized several clinical comprehensive strategies based on our clinical experience.One original concept of laser combined with radiotherapy was also introduced as a promising method,especially for wide-based pathological scars.