The Influence of Signaling on the Disfluency Effect in Multimedia Learning

Do students learn better with texts that are slightly harder-to-read (i.e., disfluent)? Previous research has yielded conflicting findings. The present study identified the boundary condition that determines when disfluent texts benefit learning. We used eye-tracking to examine the joint influence of text legibility (fluent vs. disfluent) and signaling (signaling vs. non-signaling) on multimedia learning. The results revealed that both disfluent text and signaling led to better transfer test performance, and there was also an interaction between them. Specifically, the disfluent text led to better learning outcomes with or without signaling; however, in the fluent text condition, only signaling facilitated learning. Eye movement analyses indicated that signaling guided learners to pay more attention to important content in the learning materials. The current results suggest that signaling can enhance individuals’ perceived fluency or familiarity to the material and guide the attention during multimedia learning, and the positive impact of disfluency on multimedia learning seems to be more stable and ubiquitous. We discuss these under the framework of disfluency effect and attention-guiding effect.

Microfluidic Devices with Selectable Optical Pathlength for Quality Control of Alcoholic Solutions

In this work, we present a micro-opto-fluidic platform for the analytical testing of alcoholic solutions (isopropyl alcohol, also known as isopropanol, and ethylene glycol) based on their absorption properties in the wavelength region 1.0–1.7 μm. The investigated fluidic channel is a rectangular glass microcapillary externally coated with aluminum layers, to create a zig-zag guiding effect for the radiation provided by a tungsten lamp. Light crosses the capillary multiple times before being directed towards an optical spectrum analyzer; thanks to the enhanced optical path-length inside the sample, the measurement sensitivity is strongly increased. Preliminary experimental results are reported to show sensing performances.

The Guiding Effect of Digital Image Based on Cone-Beam Computed Tomographic on Oval Root Canal Preparation

Background: To evaluate the guiding effect of digital image based on cone-beam computed tomographic in improving the quality of single oval root canal preparation.Methods: A premolar was selected by CBCT and a 3D-printed root canal model was made. Twenty postgraduates from the Department of Stomatology of Shanghai Ninth People's Hospital were selected to perform root canal preparation on 3D printed oval root canal model teeth. They were randomly assigned to two groups(n=10) according to the guiding method received: CBCT original image (control group) and CBCT-based digital image (experimental group). CBCT scans were performed on the models before and after the guidance. The changes in root canal cleanliness, residual minimum thickness, transportation and over-preparation amount were analyzed.Results: The experimental group caused significantly more increased amount of cleanliness compared to control group(P<0.05)：6.0373% ±6.0766% in the control group and 13.7193%±6.7102% in the experimental group. There was no significant difference in the reduction of residual minimum wall thickness between the two groups (P>0.05)： 0.0154mm±0.2110mm in the control group and 0.0362±0.0444mm in the experimental group. In the control group, the transportation after second preparation was generally increased (increased 0.0084mm on average). In the experimental group, the transportation was generally reduced after second preparation (reduced 0.0081mm on average). But there was no significant difference in the transportation change between the two groups (P>0.05). After the second preparation, there was no significant difference in the amount of increased over-preparation between the two groups（P＞0.05）: 1.7029%±3.6622% in the control group and 3.5144%±4.8075% in the experimental group.Conclusions: Compared with traditional CBCT image guidance, the digital image method can significantly improve the cleaning effect of the oval root canal preparation. It didn’t result in more over-preparation and the amount of residual wall thickness was ensured. At the same time, it has a certain effect on reducing transportation after the guidance.

Challenges and Advancement of Blue III-Nitride Vertical-Cavity Surface-Emitting Lasers

Since the first demonstration of (Al, In, Ga)N-based blue vertical-cavity surface-emitting lasers (VCSELs) in 2008, the maximum output power (Pmax) and threshold current density (Jth) has been improved significantly after a decade of technology advancements. This article reviewed the key challenges for the realization of VCSELs with III-nitride materials, such as inherent polarization effects, difficulties in distributed Bragg’s reflectors (DBR) fabrication for a resonant cavity, and the anti-guiding effect due to the deposited dielectrics current aperture. The significant tensile strain between AlN and GaN hampered the intuitive cavity design with two epitaxial DBRs from arsenide-based VCSELs. Therefore, many alternative cavity structures and processing technologies were developed; for example, lattice-matched AlInN/GaN DBR, nano-porous DBR, or double dielectric DBRs via various overgrowth or film transfer processing strategies. The anti-guiding effect was overcome by integrating a fully planar or slightly convex DBR as one of the reflectors. Special designs to limit the emission polarization in a circular aperture were also summarized. Growing VCSELs on low-symmetry non-polar and semipolar planes discriminates the optical gain along different crystal orientations. A deliberately designed high-contrast grating could differentiate the reflectivity between the transverse-electric field and transverse-magnetic field, which restricts the lasing mode to be the one with the higher reflectivity. In the future, the III-nitride based VCSEL shall keep advancing in total power, applicable spectral region, and ultra-low threshold pumping density with the novel device structure design and processing technologies.

Study on Eccentric Uncoupled Blasting Effect of Cutting Seam Pipe

In order to study the blasting effect and the damage to the rock mass when the cutting seam cartridge is eccentrically and uncoupled. The ANSYS/LS-DYNA® nonlinear dynamic platform was used to simulate the blasting effect of five eccentric uncoupled coefficients on the cutting seam cartridge, and the crack growth process under the condition of complete eccentricity was simulated. By comparing and analyzing the stress of measuring points in the direction of cutting seam, vertical cutting seam direction, and circumferential cutting seam pipe under different working conditions. It is concluded that the effect of detonation products is affected by the wrapping property of the cutting seam pipe and the eccentric uncoupled coefficient. With the increase of the eccentric uncoupled coefficient, the load distribution presents obvious non-uniformity. The pressure on the uncoupled side of the blasthole is smaller than that on the coupled side, and the peak time of the uncoupled side also lags behind that on the coupled side. When the eccentric uncoupled coefficient is 1, the peak pressure on the coupled side is 5.78 times that of the uncoupled side, and the explosive stress field is biased toward the coupled side. The existence of the cutting seam pipe causes stress concentration at the opening, which enhances the guiding effect of the initial crack, and the stress in the non-cutting seam direction is buffered. Therefore, the eccentric arrangement of the cutting seam pipe determines the formation of the initial crack and the subsequent blasting effect. When the cutting seam cartridge is arranged eccentrically and uncoupled, it will cause under-excavation at the connection direction of blasthole, which will cause less disturbance to the rock mass on the uncoupled side. If the retaining side rock mass is on the coupled side in actual blasting, the eccentric uncoupled arrangement will cause greater over-excavation and damage. Therefore, it is necessary to avoid this situation as far as possible and provide better guidance for the actual construction.

A novel PVDF hybrid membrane with excellent active-passive integrated antifouling and antibacterial properties based on PDA guiding effect

A novel and versatile active-passive integrated strategy to integrate both antifouling and antibacterial properties into PVDF membranes had been developed. The PDA microspheres on the modified membranes were served as...