真假“智”辨:生成式人工智能参与事实核查的价值、逻辑与强化

生成式人工智能正在强势介入信息领域,重塑信息生产和传播的流程,重建信息秩序。借助生成式人工智能辨别真假信息、进行事实核查的意义不仅仅在于其提升了对虚假信息的纠错率,解放了人工审核的劳动力,更在于以结构化内嵌的形式赋能信息社会治理,对稳定信息秩序、重塑信息格局有极大助益。本研究以问题为导向,首先分析生成式人工智能参与事实核查的难点和价值。其次,梳理当前生成式人工智能在事实核查方面的特征、技术逻辑等,对直接提问式核查和算法嵌入式核查进行归纳总结,并指出其存在的内生性矛盾。最后,在经验做法层面提出未来的治理之道。

Microenvironment and electronic state modulation of Pd nanoparticles within MOFs for enhancing low-temperature activity towards DCPD hydrogenation

Precise control of the local environment and electronic state of the guest is an important method of controlling catalytic activity and reaction pathways.In this paper,guest Pd NPs were introduced into a series of host UiO-67 MOFs with different functional ligands and metal nodes,the microenvironment and local electronic structure of Pd is modulated by introducing bipyridine groups and changing metal nodes(Ce_(6)O_(6) or Zr_(6)O_(6)).The bipyridine groups not only promoted the dispersion Pd NPs,but also facilitated electron transfer between Pd and UiO-67 MOFs through the formation of Pd-N bridges.Compared with Zr6 clusters,the tunability and orbital hybridisation of the 4f electronic structure in the Ce_(6) clusters modulate the electronic structure of Pd through the construction of the Ce-O-Pd interfaces.The optimal catalyst Pd/UiO-67(Ce)-bpy presented excellent low-temperature activity towards dicyclopentadiene hydrogenation with a conversion of>99% and a selectivity of>99%(50℃,10 bar).The results show that the synergy of Ce-O-Pd and Pd-N promotes the formation of active Pd^(δ+),which not only enhances the adsorption of H_(2) and electron-rich C=C bonds,but also contributes to the reduction of proton migration distance and improves proton utilization efficiency.These results provide valuable insights for investigating the regulatory role of the host MOFs,the nature of host-guest interactions,and their correlation with catalytic performance.

A new adaptive co-site broadband interference cancellation method with auxiliary channel

With the boom of the communication systems on some independent platforms(such as satellites,space stations,airplanes,and vessels),co-site interference is becoming prominent.The adaptive interference cancellation method has been adopted to solve the co-site interference problem.But the broadband interference cancellation performance of traditional Adaptive Co-site Interference Cancellation System(ACICS)with large delay mismatching and antenna sway is relatively poor.This study put forward an Adaptive Co-site Broadband Interference Cancellation System With Two Auxiliary Channels(ACBICS-2A).The system model was established,and the steady state weights and Interference Cancellation Ratio(ICR)were deduced by solving a time-varying differential equation.The relationship of ICR,system gain,modulation factor,interference signal bandwidth and delay mismatching degree was acquired through an in-depth analysis.Compared with traditional adaptive interference cancellation system,the proposed ACBICS-2A can improve broadband interference cancellation ability remarkably with large delay mismatching and antenna sway for the effect of auxiliary channel.The maximum improved ICR is more than 25 dB.Finally,the theoretical and simulation results were verified by experiments.

Four new observational H(z) data from luminous red galaxies in the Sloan Digital Sky Survey data release seven

By adopting the differential age method, we select 17 832 luminous red galaxies from the Sloan Digital Sky Survey Data Release Seven covering redshift 0 〈 z 〈 0.4 to measure the Hubble parameter. Using the full spectrum fitting package UZySS, these spectra are reduced with single stellar population models and optimal age information from our selected sample is derived. With the decreasing age-redshift relation, four new observational H（z） data （OHD） points are obtained, which are H（z） = 69.0 ± 19.6 km s^-1 Mpc^-1 at z = 0.07, H（z） = 68.6± 26.2 km s^-1 Mpc^-1 at z = 0.12, H（z）=72.9 ± 29.6 km s^-1 Mpc^-1 at z = 0.2 and H（z）=88.8 ± 36.6 km s^-1 Mpc^-1 at z = 0.28, respectively. Combined with 21 other available OHD data points, the performance of the constraint on both flat and non-flat ACDM models is presented.

金属有机骨架基绿色催化剂在醇氧化反应中的研究应用

醇的选择性氧化是一类非常重要的有机合成反应,因其能够生产多种高值化学品和重要的化工原料,被广泛应用于全合成、精细化工与医药等领域.目前虽已开发出多种可将醇转化为醛、酮或酸等产物的催化体系,但仍普遍存在反应条件苛刻、转化率低和选择性差等问题,且大多数催化氧化体系还涉及使用危险性氧化剂、添加剂或有毒试剂,导致产生大量有害废弃物和造成环境污染,因此开发高效、安全且环境友好的用于醇氧化绿色催化剂具有重要意义.金属有机骨架(MOFs)是一类由有机配体和金属离子/团簇组装而成的具有重复网络结构的多孔晶体材料,具有比表面积大、孔结构可调、活性位点丰富以及易于回收再利用等优点,在醇类绿色催化氧化领域中表现出巨大潜力,受到了研究者的广泛关注.MOFs还可作为载体与其它催化活性组分进行复合构筑MOFs基复合材料,或作为前驱体通过热处理等手段获得多种MOFs衍生物材料,这两类MOFs基材料在保留MOFs材料高比表面积、大孔隙率等特征的基础上,进一步集成了多元活性位点和良好结构稳定性等优势.本综述总结和讨论了近年来MOFs基材料作为绿色催化剂在醇催化氧化领域的代表性研究进展.按照MOFs基材料种类(纯MOFs、MOFs复合材料和MOFs衍生物)和反应类型(热催化、光催化和电催化)进行系统分类,并依据MOFs基材料属性(MOFs金属节点种类、MOFs基复合材料负载活性组分种类、MOFs衍生物金属中心种类以及光催化改性策略种类)对各章节内容进行了分类介绍,同时围绕材料基本合成工艺、催化反应条件及催化性能、底物普适性、醇氧化机理和材料稳定性等方面对多种所涉及的MOFs基材料进行了详细介绍,并从计算角度出发介绍了密度泛函理论(DFT)在MOFs基材料催化醇类氧化方面的应用.此外,还充分讨论了MOFs基材料作为醇氧化用绿色催化剂的基本特征、设计原则、合成策略和催化机制,并针对潜在的科学挑战提出了相应的解决方案.本文旨在介绍当前醇类氧化用MOFs基绿色催化剂及催化体系的研究现状,为高效、绿色、安全、稳定的催化新体系开发提供设计思路和理论依据,进一步推动MOFs基催化剂在醇氧化领域的规模化推广与应用.总体而言,虽然目前MOFs基材料在稳定性、规模化生产等方面仍面临诸多挑战,但随着研究的进一步深入, MOFs基催化剂在醇类绿色催化氧化领域将展现出更广阔的应用前景.

Mesoporous Ternary Nitrides of Earth?Abundant Metals as Oxygen Evolution Electrocatalyst

As sustainable energy becomes a major concern for modern society,renewable and clean energy systems need highly active,stable,and low-cost catalysts for the oxygen evolution reaction(OER).Mesoporous materials offer an attractive route for generating efficient electrocatalysts with high mass transport capabilities.Herein,we report an efficient hard templating pathway to design and synthesize three-dimensional(3-D)mesoporous ternary nickel iron nitride(Ni3FeN).The as-synthesized electrocatalyst shows good OER performance in an alkaline solution with low overpotential(259 mV)and a small Tafel slope(54 mV dec?1),giving superior performance to IrO2 and RuO2 catalysts.The highly active contact area,the hierarchical porosity,and the synergistic effect of bimetal atoms contributed to the improved electrocatalytic performance toward OER.In a practical rechargeable Zn–air battery,mesoporous Ni3FeN is also shown to deliver a lower charging voltage and longer lifetime than RuO2.This work opens up a new promising approach to synthesize active OER electrocatalysts for energy-related devices.

Toward intelligent wireless communications:Deep learning-based physical layer technologies

Advanced technologies are required in future mobile wireless networks to support services with highly diverse requirements in terms of high data rate and reliability,low latency,and massive access.Deep Learning(DL),one of the most exciting developments in machine learning and big data,has recently shown great potential in the study of wireless communications.In this article,we provide a literature review on the applications of DL in the physical layer.First,we analyze the limitations of existing signal processing techniques in terms of model accuracy,global optimality,and computational scalability.Next,we provide a brief review of classical DL frameworks.Subsequently,we discuss recent DL-based physical layer technologies,including both DL-based signal processing modules and end-to-end systems.Deep neural networks are used to replace a single or several conventional functional modules,whereas the objective of the latter is to replace the entire transceiver structure.Lastly,we discuss the open issues and research directions of the DL-based physical layer in terms of model complexity,data quality,data representation,and algorithm reliability.

Production of reactive oxygen species by PuRBOHF is critical for stone cell development in pear fruit

The production of reactive oxygen species(ROS)by NADPH oxidase,which is also referred to as respiratory burst oxidase homolog(RBOH),affects several processes in plants.However,the role of RBOHs in cell wall lignification is not well understood.In this study,we show that PuRBOHF,an RBOH isoform,plays an important role in secondary wall formation in pear stone cells.ROS were closely associated with lignin deposition and stone cell formation according to microscopy data.In addition,according to the results of an in situ hybridization analysis,the stage-specific expression of PuRBOHF was higher in stone cells than in cells of other flesh tissues.Inhibitors of RBOH activity suppressed ROS accumulation and stone cell lignification in pear fruit.Moreover,transient overexpression of PuRBOHF caused significant changes in the amount of ROS and lignin that accumulated in pear fruit and flesh calli.We further showed that PuMYB169 regulates PuRBOHF expression,while PuRBOHF-derived ROS induces the transcription of PuPOD2 and PuLAC2.The findings of this study indicate that PuRBOHF-mediated ROS production,which is regulated by a lignin-related transcriptional network,is essential for monolignol polymerization and stone cell formation in pear fruit.

Nanocomposites of graphene-CdS as photoactive and reusable catalysts for visible-light-induced selective reduction process

Graphene （GR）-CdS nanocomposites with different weight addition ratios of GR have been assembled by a facile solvothermal treatment. The GR-CdS nanocomposite photocatalyst with an appropriate ratio of GR exhibits enhanced photoactivity for selective reduction of aromatic nitro compounds to the corresponding aromatic amines in water under visible light irradiation as compared with blank-CdS. The characterization of GR-CdS nanocomposite photocatalysts by a collection of techniques discloses that： i） GR can tune the microscopic morphology of CdS nanoparticles and improve light absorption intensity in the visible light region; ii） GR scaffolds act as an electron reservoir to trap and shuttle the electrons photogenerated from CdS semiconductor under the visible light illumination; iii） the introduction of GR enhances the adsorption capacity of GR-CdS nanocomposites toward the substrates, aromatic nitro compounds. The synergistic effect of these factors should account for the photoactivity advancement of GR-CdS nanocomposites toward the probe reactions. Furthermore, because the photogenerated holes in the system are trapped by the quenching agent ammonium oxalate, the as-obtained GR-CdS photocataiyst is stable during the photocatalytic reduction reactions. A reasonable model has also been proposed to illustrate the reaction mechanism.

Electrostatic self-assembly of CdS nanowires-nitrogen doped graphene nanocomposites for enhanced visible light photocatalysis

CdS nanowires-nitrogen doped graphene （CdS NWs-NGR） nanocomposites have been fabricated by an electrostatic self-assembly strategy followed by a hydrothermal reduction. The CdS NWs-NGR exhibits higher photoactivity for selective reduction of aromatic nitro organics in water under visible light irradiation than blank CdS nanowires （CdS NWs） and CdS nanowires-reduced graphene oxide （CdS NWs-RGO） nanocomposites. The enhanced photoactivity of CdS NWs-NGR can be attributed to the improved electronic conductivity due to the introduc- tion of nitrogen atoms, which thus enhances the separation and transfer of charge carriers photogenerated from CdS NWs. Our work could provide a facile method to synthesize NGR based one-dimensional （1D） semiconductor composites for selective organic transformations, and broaden the potential applications for NGR as a cocatalyst.

红细胞分布宽度及血脂在肝硬化食管胃底静脉曲张破裂出血中的临床价值

目的探讨红细胞分布宽度(red cell distribution width,RDW)及血脂与肝硬化伴食管胃底静脉曲张破裂出血(gastroesophageal variceal bleeding,GEVB)的相关性及临床价值。方法以昆明市第三人民医院肝病综合科2021年1月至2021年5月期间收治住院的发生GEVB的肝硬化患者60例为出血组,随机选取同期住院的未发生GEVB的肝硬化患者60例为未出血组。对比分析2组患者的基本资料、RDW、PLT、肝功能生化指标和血脂相关指标,然后通过多因素二元Logistic回归分析探索RDW和血脂对GEVB的影响,最后用ROC曲线判断其诊断效能。结果与未出血组相比,出血组RDW升高,TG、TC、HDL-C、LDL-C、ApoA1、ApoE降低(均P<0.05)。二元Logistic回归分析提示,RDW是肝硬化患者发生GEVB的独立危险因素(OR=1.367,95%CI:1.141~1.639),TC是肝硬化患者发生GEVB的独立保护因素(OR=0.437,95%CI:0.262~0.728)(均P<0.05)。通过绘制ROC曲线提示,RDW诊断GEVB的曲线下面积(AUC)为0.803(P<0.05),最佳临界值15.25%,敏感度为86.7%、特异性为63.3%;TC诊断GEVB的AUC为0.789(P<0.05),最佳临界值2.765 mmol/L,敏感度为78.3%、特异性为75.0%。结论RDW及TC对于肝硬化患者发生GEVB具有较高的判断价值,临床需高度重视。

Realizing high-performance organic solar cells through precise control of HOMO driving force based on ternary alloy strategy

A good deal of studies have proven that effective exciton dissociation and fast hole transport can operate efficiently in non-fullerene organic photovoltaics(OPVs)despite nearly zero driving force.Even so,whether such a phenomenon is universal and how small the driving force can realize the best photovoltaic performance still require a thorough understanding.Herein,despite the zero driving force based on PM6:F8IC system,a maximum short-circuit current(J_(sc))of 23.0 mA/cm^(2) and high power conversion efficiency(PCE)of 12.2%can still be achieved.Due to the continuously adjustable energy levels can be realized in organic semiconducting alloys including F8IC:IT-4F and F8IC:Y6,the suitable third components can play the role of energy level regulator.Therefore,the HOMO energy level offset(DEHOMO(D A))from zero to 0.07 and 0.06 eV is accomplished in the optimized IT-4F and Y6 ternary devices.Consequently,both ternary devices achieved substantially increased PCE of 13.8%and Jsc of 24.4 and 25.2 mA/cm^(2),respectively.Besides,pseudo-planar heterojunction(PPHJ)devices based on alloyed acceptors through sequential spin-coating method further improve the photovoltaic performance.Our work puts forward the concept of energy level regulator and prove that the ternary alloy strategy has unique advantages and huge research potential in continuously adjusting the driving force.

High-Density Block Transformation to Increase Natural Ventilation Based on CFD Simulation

Many countries in the world have experienced extremely rapid urbanization during recent decades. The rapiddevelopment of densely populated areas has produced many urban environmental problems. This researchexplores the relationship between urban morphology and ventilation conditions. Through 3D modeling andComputational Fluid Dynamics (CFD) simulation, we focus on the large scale ventilation of an extended area withseveral buildings. As a testbed, in particular, the core part of Kwun Tong industrial park in Hong Kong is examined, and in order to validate the approach, 10 measurement points are used to get experimental values to be usedfor comparison (such points are located in different positions involving traffic road, pedestrian path and openspace). The error range (±0.7 m/s) indicates that the agreement between field measurement and CFD calculationis good. On the basis of design guidelines and earlier studies, the effective configuration (in terms of building) ofthis area is partially transformed (virtually, i.e., in the numerical simulations) in order to assess the ensuingchanges in terms of wind speed in different locations. This results in a general design and analysis methodologypotentially applicable to other areas.

Dietary calcium supplementation promotes the accumulation of intramuscular fat

Background:In the livestock industry,intramuscular fat content is a key factor affecting meat quality.Many studies have shown that dietary calcium supplementation is closely related to lipid metabolism.However,few studies have examined the relationship between dietary calcium supplementation and intramuscular fat accumulation.Methods:Here,we used C2C12 cells,C57BL/6 mice(n=8)and three-way cross-breeding pigs(Duroc×Landrace×Large white)(n=10)to study the effect of calcium addition on intramuscular fat accumulation.In vitro,we used calcium chloride to adjust the calcium levels in the medium(2 mmol/L or 3 mmol/L).Then we measured various indicators.In vivo,calcium carbonate was used to regulate calcium levels in feeds(Mice:0.5%calcium or 1.2%calcium)(Pigs:0.9%calcium or 1.5%calcium).Then we tested the mice gastrocnemius muscle triglyceride content,pig longissimus dorsi muscle meat quality and lipidomics.Results:In vitro,calcium addition(3 mmol/L)had no significant effect on cell proliferation,but promoted the differentiation of C2C12 cells into slow-twitch fibers.Calcium supplementation increased triglyceride accumulation in C2C12 cells.Calcium addition increased the number of mitochondria and also increased the calcium level in the mitochondria and reduced the of key enzymes activity involved inβ-oxidation such as acyl-coenzyme A dehydrogenase.Decreasing mitochondrial calcium level can alleviate lipid accumulation induced by calcium addition.In addition,calcium addition also reduced the glycolytic capacity and glycolytic conversion rate of C2C12 cells.In vivo,dietary calcium supplementation(1.2%)promoted the accumulation of triglycerides in the gastrocnemius muscle of mice.Dietary calcium supplementation(1.5%)had no effect on pig weight,but significantly improved the flesh color of the longissimus dorsi muscle,reduced the backfat thickness and increased intramuscular fat content in pigs.Besides,calcium addition had no effect on longissimus dorsi pH,electrical conductivity and shear force.Conclusions:These results suggest that calcium addition promotes intramuscular fat accumulation by inhibiting the oxidation of fatty acids.These findings provide a new tool for increasing intramuscular fat content and an economical strategy for improving meat quality.

The Significance of Thermally Pulsing Asymptotic Giant Branch Stars in Post-starburst Galaxies

We measure the significance of thermally pulsing asymptotic giant branch(TP-AGB)stars via the spectral energy distributions(SEDs)of a sample of post-starburst(PSB)galaxies at z=0.2-0.7.Using ground-and space-based photometry from the 3D-HST catalog,as well as associated near-infrared(NIR)Hubble Space Telescope(HST)slitless grism spectroscopy,we evaluate the importance of TP-AGB stars in the SEDs of 177 PSB galaxies by fitting simple stellar populations with different levels of TP-AGB contributions.The grism spectra,despite their low resolution of R~100,enable the detection of molecular features specific to TP-AGB stars and thus improve constraints on their contribution.A majority(~70%)of galaxies in the PSB sample show features indicative of TPAGB stars,while the remainder does not and they are well fit by Bruzual&Charlot TP-AGB light models.Stacked spectra of sources classified to be the best fit by TP-AGB heavy/mild models reveal strong detections of NIR molecular features associated with TP-AGB stars.Additionally,we observe a tentative trend with redshift where more TP-AGB heavy galaxies are observed in the higher redshift PSB galaxy population.Finally,neglecting the contribution of TP-AGB stars can yield an over-prediction of stellar masses measured in the K-band ranging from 0.13-0.23 dex.

A review of anomalous refractive and reflective metasurfaces

Abnormal refraction and reflection refers to the phenomenon in which light does not follow its traditional laws of propagation and instead is subject to refraction and reflection at abnormal angles that satisfy a generalization of Snell’s law.Metasurfaces can realize this phenomenon through appropriate selection of materials and structural design,and they have a wide range of potential applications in the military,communications,scientific,and biomedical fields.This paper summarizes the current state of research on abnormal refractive and reflective metasurfaces and their application scenarios.It discusses types of abnormal refractive and reflective metasurfaces based on their tuning modes(active and passive),their applications in different wavelength bands,and their future development.The technical obstacles that arise with existing metasurface technology are summarized,and prospects for future development and applications of abnormal refractive and reflective metasurfaces are discussed.

The HⅠGas Fraction Scaling Relation of the Green Pea Galaxies

Green Pea galaxies are compact galaxies with high star formation rates.However,limited samples of Green Pea galaxies have H I 21 cm measurements.Whether the H I gas fraction(fH I≡MH I/M_(★))of Green Pea galaxies follows the existing scaling relations between the fH Iand NUV-r color or linear combinations of color and other physical quantities needs checking.Using archival data of H I 21 cm observations,we investigate the scaling relation of the NUV-r color with the MH I/M_(★)of 38 Green Pea galaxies,including 17 detections and 21 nondetections.The H I to stellar mass ratios(fH I)of Green Pea galaxies deviate from the polynomial form,where a higher H I gas fraction is predicted given the current NUV-r color,even with the emission lines removed.The blue sources(NUV-r<1)from the comparison sample(ALFALFA-SDSS)follow a similar trend.The H I gas fraction scaling relations with linear combination forms of-0.34(N UV-r)-0.64 log(μ_(★,z))+5.9 and-0.77 log_(μ_(★)),i+0.26logS FRM_(★)+8.53,better predict the H I gas fraction of the Green Pea galaxies.In order to obtain accurate linear combined forms,higher-resolution photometry from space-based telescopes is needed.

A Real-Time Pedestrian Social Distancing Risk Alert System for COVID-19

The COVID-19 virus is usually spread by small droplets when talking,coughing and sneezing,so maintaining physical distance between people is necessary to slow the spread of the virus.The World Health Organization(WHO)recommends maintaining a social distance of at least six feet.In this paper,we developed a real-time pedestrian social distance risk alert system for COVID-19,whichmonitors the distance between people in real-time via video streaming and provides risk alerts to the person in charge,thus avoiding the problem of too close social distance between pedestrians in public places.We design a lightweight convolutional neural network architecture to detect the distance between people more accurately.In addition,due to the limitation of camera placement,the previous algorithm based on flat view is not applicable to the social distance calculation for cameras,so we designed and developed a perspective conversion module to reduce the image in the video to a bird’s eye view,which can avoid the error caused by the elevation view and thus provide accurate risk indication to the user.We selected images containing only person labels in theCOCO2017 dataset to train our networkmodel.The experimental results show that our network model achieves 82.3%detection accuracy and performs significantly better than other mainstream network architectures in the three metrics of Recall,Precision and mAP,proving the effectiveness of our system and the efficiency of our technology.

Metabolomics research on Tibetan medicinal substances

Background:Tibetan medicinal substances(TMS)has a complete theory that is based on five source doctrines.The theories of“Liuwei”,“Baxing”,“Shiqi Gongxiao”,and“Sanhuawei”constitute the prominent core components of the five source doctrines with significant Tibetan characteristics.Objective:This review summarizes the existing literature on the metabolomics and its use in TMS and offers recommendations for future research.Methods:Studies on TMS and the application of metabolomics on TMS are reviewed and summarized.The shortcomings of existing studies and recommendations for future studies are discussed.Conclusions:The recent researches have studied on the theory of TMS.Metabolomics will be increasingly applied to the identification of compounds in TMS,and the resultant detection of biomarkers will help elucidate the metabolic pathways of these substances.

炎症性肠病患儿英夫利西单抗的治疗药物监测研究进展

抗肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)制剂,如英夫利西单抗(infliximab,IFX),是我国目前具有儿童炎症性肠病(inflammatory bowel disease,IBD)应用适应证的生物制剂。随着IFX的临床应用,IBD的治疗目标从临床缓解转向黏膜愈合,从而进一步改善疾病的转归。但临床工作中发现部分患儿对IFX治疗原发性无应答或继发性失应答,这是IFX治疗过程中的一大难题,研究发现这一现象可能与血药浓度降低及抗药抗体的产生相关。因此,IFX的治疗药物监测(therapeutic drug monitoring,TDM)在儿童IBD治疗中非常重要。该文综述了IFX治疗儿童IBD过程中TDM的应用现状,并对TDM未来的研究方向提出展望。