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We present facile synthesis of bright CdS/CdSe/CdS@SiO nanoparticles with 72% of quantum yields (QYs) retaining ca 80% of the original QYs. The main innovative point is the utilization of the highly luminescent CdS/CdSe/CdS seed/spherical quantum well/shell (SQW) as silica coating seeds. The significance of inorganic semiconductor shell passivation and structure design of quantum dots (QDs) for obtaining bright QD@SiO is demonstrated by applying silica encapsulation via reverse microemulsion method to three kinds of QDs with different structure: CdSe core and 2 nm CdS shell (CdSe/CdS-thin); CdSe core and 6 nm CdS shell (CdSe/CdS-thick); and CdS core, CdSe intermediate shell and 5 nm CdS outer shell (CdS/CdSe/CdS-SQW). Silica encapsulation inevitably results in lower photoluminescence quantum yield (PL QY) than pristine QDs due to formation of surface defects. However, the retaining ratio of pristine QY is different in the three silica coated samples; for example, CdSe/CdS-thin/SiO shows the lowest retaining ratio (36%) while the retaining ratio of pristine PL QY in CdSe/CdS-thick/SiO and SQW/SiO is over 80% and SQW/SiO shows the highest resulting PL QY. Thick outermost CdS shell isolates the excitons from the defects at surface, making PL QY relatively insensitive to silica encapsulation. The bright SiO-coated SQW sample shows robustness against harsh conditions, such as acid etching and thermal annealing. The high luminescence and long-term stability highlights the potential of using the SQW/SiO nanoparticles in bio-labeling or display applications.

While investigating multiphase flows experimentally, the spatiotemporal variation in the interfacial shape between different phases must be measured to analyze the transport phenomena. For this, numerous image processing techniques have been proposed, showing good performance. However, they require trial-and-error optimization of thresholding parameters, which are not universal for all experimental conditions; thus, their accuracy is highly dependent on human experience, and the overall processing cost is high. Motivated by the remarkable improvements in deep learning-based image processing, we trained the Mask R-CNN to develop an automated bubble detection and mask extraction tool that works universally in gas–liquid two-phase flows. The training dataset was rigorously optimized to improve the model performance and delay overfitting with a finite amount of data. The range of detectable bubble size (particularly smaller bubbles) could be extended using a customized weighted loss function. Validation with different bubbly flows yields promising results, with AP50reaching 98%. Even while testing with bubble-swarm flows not included in the training set, the model detects more than 95% of the bubbles, which is equivalent or superior to conventional image processing methods. The pure processing speed for mask extraction is more than twice as fast as conventional approaches, even without counting the time required for tedious threshold parameter tuning. The present bubble detection and mask extraction tool is available online (https://github.com/ywflow/BubMask).

Transition metal dichalcogenides (TMDs) are of great interest owing to their unique properties. However, TMD materials face two major challenges that limit their practical applications: contact resistance and surface contamination. Herein, a strategy to overcome these problems by inserting a monolayer of hexagonal boron nitride (h‐BN) at the chromium (Cr) and tungsten disulfide (WS2) interface is introduced. Electrical behaviors of direct metal–semiconductor (MS) and metal–insulator–semiconductor (MIS) contacts with mono‐ and bilayer h‐BN in a four‐layer WS2 field‐effect transistor (FET) are evaluated under vacuum from 77 to 300 K. The performance of the MIS contacts differs based on the metal work function when using Cr and indium (In). The contact resistance is significantly reduced by approximately ten times with MIS contacts compared with that for MS contacts. An electron mobility up to ≈115 cm2 V‐1 s‐1 at 300 K is achieved with the insertion of monolayer h‐BN, which is approximately ten times higher than that with MS contacts. The mobility and contact resistance enhancement are attributed to Schottky barrier reduction when h‐BN is introduced between Cr and WS2. The dependence of the tunneling mechanisms on the h‐BN thickness is investigated by extracting the tunneling barrier parameters.

A relatively new cognitive-affective training procedure, the Attentional Bias Modification (ABM) technique, is thought to decrease biases in the allocation of attention toward negative emotional stimuli. In two studies, we tested in samples of healthy students whether a single session of ABM has an influence on early orienting of spatial attention as indexed by the N2pc. Replicating previous studies, we found an occipitotemporal N2pc (180-300  ms) contralateral to angry versus neutral facial expressions, indicating that threatening faces automatically draw attention in early stages of stimulus processing. However, this N2pc effect did not significantly change during the ABM training session. Our results therefore indicate that a single session of ABM does not affect early attentional orienting. ABM effects reported in prior research may therefore have been mediated by later cognitive-affective mechanisms.