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In this paper, we study the problem of predicting popularities of questions in Community Question Answering (CQA). To address this problem, we propose a Posterior Attention Recurrent Point Process Model (PARPP) to take both the interaction of users and the Matthew effect into account for question popularity prediction. Our PARPP uses long short-term memory (LSTM) to encode the observed history and another LSTM network to record each step of decoding information. At each decoding step, it uses prior attention to capture answers that have a greater impact on the problem. When a new answer is observed, it uses Bayes' rule to modify prior attention and obtain posterior attention. Then, the posterior attention is used to update the decoding status. We further introduce a convergence strategy to capture the Matthew effect in CQA. We conduct experiments on a Zhihu dataset crawled from a famous Chinese CQA forum. The experimental results show that our model outperforms several state-of-the-art methods. We further analyze the attention mechanism in our model. Our analysis shows that the proposed attention mechanism can better capture the impact of each answer on the future popularity of the question, which makes our model more interpretable. Our study would shed light on other similar studies such as answer ranking in response to the question and finding experts who have expertise on the topics of the questions. [ABSTRACT FROM AUTHOR]

The first asymmetric mode (A1 mode) lamb wave resonator (LWR) with a resonant frequency of 6 GHz based on Z-cut lithium niobate (LN) films is presented. An asymmetric electrode structure with different-sized electrode pads in the center and edged regions has been proposed, which can be used to optimize the distribution of the electric field and decrease acoustic impedance mismatch to improve the target mode. Experiment results reveal that LWRs with an asymmetric electrode structure can successfully enhance the A1 mode, achieving a high effective electromechanical coefficient ( k eff 2 ) of 26%, a quality factor (Q) of 1123, and an excellent figure-of-merit (FOM = k eff 2 ∙ Q) of 262. It demonstrates that asymmetric electrode structure provides a new way to suppress the spurious modes for LWRs and shows a great application prospect in wide-bandwidth and low-loss filters used in the sub-6 G frequency range. [ABSTRACT FROM AUTHOR]

We report a new quaternary compound, ThV2Si2C, containing V2C square nets that are sandwiched by Si sheets. The compound crystallizes in a CeCr2Si2C-type structure with cell parameters of a = b = 4.1008 Å and c = 5.4150 Å. Magnetic, electrical transport, and specific heat measurements confirm the Pauli paramagnetic metal behavior in ThV2Si2C, concomitant with low magnetoresistance. At temperatures below 2 K, a possible weak superconducting transition is found. First-principles calculations reveal that V-3d orbitals dominate the electronic states at around the Fermi energy. These states predominantly originate from the dx2−y2, dz2, and dyz orbitals, defining the primarily anisotropic nature of conduction within the V2Si2C block. The differences in the orbital-dependent pairing among charge carriers within isomorphic compounds are discussed. [ABSTRACT FROM AUTHOR]

Titanium carbide quantum dots (Ti3C2 QDs) are derived from MXenes, an emerging layered two-dimensional material. Ti3C2 QDs exhibit better chemical stability, dispersibility, and photoluminescence than MXenes and have great application potential in biological imaging, environmental pollution, and food safety. Ascorbic acid (AA), a key coenzyme in human metabolic pathways, plays an important role in various physiological reactions. Herein, a fluorescent sensor to detect AA is designed by combining Ti3C2 QDs with cobalt oxy-hydroxide (CoOOH) nanosheets. CoOOH nanosheets, as effective fluorescence quenching agents, can considerably quench the fluorescence of Ti3C2 QDs. During the detection process, AA is oxidized to dehydroascorbic acid and CoOOH nanosheets are reduced to Co2+ and disintegrated, resulting in the recovery of the fluorescence intensity of Ti3C2 QDs. Therefore, AA is detected by monitoring the degree of recovery of the fluorescence intensity of Ti3C2 QDs. The fluorescent sensor exhibits a linear range of 0–100 μM and a detection limit of 0.19 μM for AA. Its recovery rates in commercial orange juice and watermelon juice are 97.12–103.95% and 94.46–107.32%, respectively, and it exhibits good detection reproducibility. This fluorescent sensor can be used to measure the AA concentration in fruits and beverages. [ABSTRACT FROM AUTHOR]