专业事实核查机构在社交媒体中的“点击诱饵”及其传播效果研究

本研究考察了事实核查机构使用“点击诱饵元素”的现状,并对其传播效果进行评估。本研究通过人工标注样本以训练机器学习模型的方法,分析了12家美国专业事实核查机构过去两年间在其推特账号上发布的24670条用于推广核查报告的推文。研究发现,五分之一的推文包含点击诱饵元素。对于有影响的事实核查机构而言,当其在核查时政和公共卫生议题时,点击诱饵元素对推文的传播效果有负面影响。本研究讨论了该结果对理论、方法和网络内容管理实践层面的启示。

Contact optimisation strategy for wafer-scale field-effect transistors based on two-dimensional semiconductors

Two-dimensional(2D)semiconductors can be utilized to continually miniaturize nanoscale electronic de-vices.However,achieving a practical solution for satisfying electrical contact with 2D semiconductors remains challenging.In this study,we developed a novel contact structure with transferred multilayer(t-ML)MoS 2 by integrating both edge and top contact.After in-situ plasma treatment for the edge of the MoS 2 channel and successive metal deposition,we achieved 16 times lower contact resistivity(22.8 kΩμm)than that of the top contacted devices.The thickness-dependent electrical measurement indicates that edge contact is highly effective with thick MoS 2 due to the alleviated current-crowding effect re-sulting from the small contact area.The temperature-dependent transport measurement further confirms the effective minimization of the influence from the Schottky barrier and tunnelling barrier.Finally,the simplified resistor network model and energy-band diagram were proposed to understand the carrier transport mechanism.Our work provides a practical strategy for achieving excellent electrical contact between bulk metals and 2D semiconductors,paving the way for future large-scale 2D electronic devices.

A coaxially extruded heterogeneous core-shell fiber with Schwann cells and neural stem cells

Cellular therapies play a critical role in the treatment of spinal cord injury(SCI).Compared with cell-seeded conduits,fully cellular grafts have more similarities with autografts,and thus might result in better regeneration effects.In this study,we fabricated Schwann cell(SC)-neural stem cell(NSC)core–shell alginate hydrogel fibers in a coaxial extrusion manner.The rat SC line RSC96 and mouse NSC line NE-4C were used in this experiment.Fully cellular components were achieved in the core portion and the relative spatial positions of these two cells partially mimic the construction of nerve fibers in vivo.SCs were demonstrated to express more genes of neurotrophic factors in alginate shell.Enhanced proliferation and differentiation tendency of NSCs was observed when they were co-cultured with SCs.This model has strong potential for application in SCI repair.

Stacking monolayers at will:A scalable device optimization strategy for two-dimensional semiconductors

In comparison to monolayer(1L),multilayer(ML)two-dimensional(2D)semiconducting transition metal dichalcogenides(TMDs)exhibit more application potential for electronic and optoelectronic devices due to their improved current carrying capability,higher mobility,and broader spectral response.However,the investigation of devices based on wafer-scale ML-TMDs is still restricted by the synthesis of uniform and high-quality ML films.In this work,we propose a strategy of stacking MoS_(2) monolayers via a vacuum transfer method,by which one could obtain wafer-scale high-quality MoS_(2) films with the desired number of layers at will.The optical characteristics of these stacked ML-MoS_(2) films(>2L)indicate a weak interlayer coupling.The stacked MLMoS_(2) phototransistors show improved optoelectrical performances and a broader spectral response(approximately 300-1,000 nm)than that of 1L-MoS_(2).Additionally,the dual-gate ML-MoS_(2) transistors enable enhanced electrostatic control over the stacked ML-MoS_(2) channel,and the 3L and 4L thicknesses exhibit the optimal device performances according to the turning point of the current on/off ratio and the subthreshold swing.

Microstructure investigation of dynamic recrystallization in hard machining:From thermodynamic irreversibility perspective

The drastically changed thermal,mechanical,and chemical energies within the machined surface layer during hard machining tend to initiate microstructural alteration.In this paper,attention is paid to the introduction of thermodynamic potential to unravel the mechanism of microstructure evolution.First,the thermodynamic potential-based model expressed by the Helmholtz free energy was proposed for predicting the microstructure changes of serrated chip and the machined surface layer.Second,the proposed model was implemented into a validated finite element simulation model for cutting operation as a user-defined subroutine.In addition,the predicted irreversible thermodynamic state change in the deformation zones associated with grain size,which was reduced to less than 1 mm from the initial size of 1.5 mm on the machined surface,was provided for an in-depth explanation.The good consistency between the simulated results and experimental data validated the efficacy of the developed model.This research helps to provide further insight into the microstructure alteration during metal cutting.

Atomic scale memristive photon source

Memristive devices are an emerging new type of devices operating at the scale of a few or even single atoms.They are currently used as storage elements and are investigated for performing in-memory and neuromorphic computing.Amongst these devices,Ag/amorphous-SiO_(x)/Pt memristors are among the most studied systems,with the electrically induced filament growth and dynamics being thoroughly investigated both theoretically and experimentally.In this paper,we report the observation of a novel feature in these devices:The appearance of new photoluminescent centers in SiO_(x) upon memristive switching,and photon emission correlated with the conductance changes.This observation might pave the way towards an intrinsically memristive atomic scale light source with applications in neural networks,optical interconnects,and quantum communication.