Mechanism of significantly enhanced piezoelectric performance and stability in textured potassium-sodium niobate piezoelectric ceramics

In this study, the piezoelectric coefficient d₃₃ and planar electromechanical coupling coefficient k_p were enhanced 145% and 71%, respectively for the <001>-textured (K_0.5Na_0.5)_0.95Li_0.05Nb_0.93Sb_0.07O₃ piezoelectric ceramics compared with their randomly oriented counterpart. Significantly enhanced piezoelectric response in textured ceramics is originated from a combined effect of the intrinsic high piezoelectric activity of <001>-oriented grains in the tetragonal-orthorhombic phases, and easy polarization rotation of fine domains. Furthermore, a comparative analysis suggests that <001>-textured ceramics exhibit good thermal stability, benefiting from the weakened depolarization behavior via crystal orientation. The superior fatigue resistance in textured ceramics can be attributed to the reduced clamping effect as low defect density. These results show that high-performance textured ceramics reported in this work will be promising candidates in the field of lead-free piezoelectric materials.     

Experimental research on dynamic response of PZT-5H under impact load

In order to improve the stability of PZT-based sensors, the mechanical, dielectric, ferroelectric and piezoelectric properties of PZT-5H under impact load were studied experimentally by using the separated Hopkinson pressure bar (SHPB) with an electrical output measurement device. At the same time, the experimental study on the material properties of PZT-5H before and after the impact was carried out. The effect of impact cracks on the output voltage of PZT-5H was also analyzed. The results show that the dynamic piezoelectric constants of PZT-5H under low stress impact (10–50 MPa) are different from those under quasi-static state, and the empirical relationship between them and the peak stress is obtained through experiments. The dielectric properties of PZT-5H did not change under low stress impact, but micro-cracks occurred in the material and dielectric loss increased at high frequencies. Under short circuit, the residual polarization intensity of PZT-5H decreases sharply due to impact load. While the impact load causes the secondary polarization and the increase of the residual polarization intensity of PZT under open circuit. When the stress is over 45 MPa, the PZT-5H breaks. The formation of cracks causes abnormal discharge voltage and gap discharge.     

Dynamic Passivation in Perovskite Quantum Dots for Specific Ammonia Detection at Room Temperature

Perovskite structured CsPbX₃ (X = Cl, Br, or I) quantum dots (QDs) have attracted considerable interest in the past few years due to their excellent optoelectronic properties. Surface passivation is one of the main pathways to optimize the optoelectrical performance of perovskite QDs, in which the amino group plays an important role for the corresponding interaction between lead and halide. In this work, it is found that ammonia gas could dramatically increase photoluminescence of purified QDs and effectively passivate surface defects of perovskite QDs introduced during purification, which is a reversible process. This phenomenon makes perovskite QDs a kind of ideal candidate for detection of ammonia gas at room temperature. This QD film sensor displays specific recognition behavior toward ammonia gas due to its significant fluorescence enhancement, while depressed luminescence in case of other gases. The sensor, in turn‐on mode, shows a wide detection range from 25 to 350 ppm with a limit of detection as low as 8.85 ppm. Meanwhile, a fast response time of ≈10 s is achieved, and the recovery time is ≈30 s. The fully reversible, high sensitivity and selectivity characteristics make CsPbBr₃ QDs ideal active materials for room‐temperature ammonia sensing.     

The potential of energy flexibility of space heating and cooling in Portugal

This study assesses the potential of energy flexibility of space heating and cooling for a typical household under different geographical conditions in Portugal. The proposed approach modifies the demand through the optimization of the thermostat settings using a genetic algorithm to reduce either operational costs or interaction with the grid. The results show that the used energy flexibility indicator expresses the available potential and that flexibility depends on several factors, namely: i) thermal inertia of the archetypical household; ii) the time of use electricity tariffs; iii) users’ comfort boundaries; and iv) the geographical location of the houses.     

Risk-constrained probabilistic optimal scheduling of FCPP-CHP based energy hub considering demand-side resources

Renewable energy sources (RES) with sharing a large percentage of future energy generation capacities play an essential role in the decarbonization of the future electricity and thermal networks as well as transportation sectors. However, the uncertainties in their outputs make some difficulties in making operational decisions. Hydrogen energy plays a considerable role in this concept. Besides, energy hubs (EHs) provide an efficient and reliable framework for gathering multi-type energy carriers.This paper optimally schedules the operating of the EH and decreases the emission cost, considering the electrical and thermal demand response (DR) program in a probabilistic environment. Besides plug-in electric vehicles (PEVs) and a complete model of hydrogen-based renewable energy sources are presented in the EH. Taking into account uncertainties of electrical/thermal energy markets real-time prices, customers' energy demand, and energy production of RESs into account, various scenarios are generated using the Monte Carlo simulation technique. Next, an efficient method is used to reduce the number of the scenario to make the optimization problem computable and fast. In order to reduce the risk of encountering high operating costs, the conditional value at risk (CVaR) technique is used to manage the associated risk. Simulation results show the efficiency of the proposed method in decreasing the operational cost and managing the risk of encountering unfavorable states.     

Carbon membrane bridged ZnSe and TiO2 nanotube arrays: Fabrication and promising application in photoelectrochemical water splitting

In this work, a cascade structure among ZnSe, carbon membrane and TiO₂ NTAs was constructed precisely. This carbon membrane bridged ZnSe and TiO₂ composite exhibits excellent H₂ evolution activity, the H₂ evolution rate of ZnSe/C/TiO₂ NTAs (866.76 μmol/cm²) is about 6.95 times higher than that of pure TiO₂ NTAs (124.64 μmol/cm²) after 200 min irradiation. The introduction of carbon membrane can greatly facilitate the electron transfer from ZnSe to TiO₂, ZnSe/C/TiO₂ ternary composite exhibits the highest transient photocurrent density (1.05 mA/cm²) and the lowest impedance (677.6 Ω) among all the samples. Besides, the contact between TiO₂ and electrolyte is improved after introducing carbon membrane, therefore C/TiO₂ NTAs shows more positive flat band potential of (1.86 V) compared with TiO₂ NTAs (0.50 V). It is also found that pure carbon powder can achieve H₂ production under visible light irradiation, its sensitization effect can further improve photocurrent density of the composite under 500 nm light radiation, the electrons produced in carbon film can inject into TiO₂, and holes from TiO₂ can quickly transfer to carbon film, leading to excellent H₂ evolution efficiency.     

应用响应曲面模型法研究丙泊酚与瑞芬太尼的最佳配伍剂量

目的:应用响应曲面模型法研究丙泊酚与瑞芬太尼合用抑制喉镜置入刺激的体动反应、循环反应及出现循环抑制副作用，评估两药相互作用方式和程度，并探索丙泊酚与瑞芬太尼最佳配伍剂量范围。方法:ASA Ⅰ-Ⅱ级患者70例，随机平行分组，选择一个预设的丙泊酚靶控输注浓度并维持丙泊酚靶浓度不变，阶梯式增加瑞芬太尼的靶浓度，评估喉镜置入刺激的体动反应、循环反应和循环抑制副作用。应用响应曲面模型分析丙泊酚与瑞芬太尼的药效学相互作用，构建最佳反应阈值范围。结果:响应曲面模型显示丙泊酚（≤9 μg/mL）和瑞芬太尼（≤10 ng/mL）联合使用在抑制喉镜置入体动反应、循环反应和产生循环抑制副作用有明显协同作用，Imax分别为2.89、5.02和2.55。将不同药效学观察指标的响应曲面相结合，构建出最佳配伍剂量范围。结论:响应曲面模型可以定性并定量的研究丙泊酚与瑞芬太尼之间的药物相互作用，并创建最佳反应阈值范围。     

Functions of ULK1 in autophagy and non-autophagy pathways and its implications in human physiology and disease

ULK1 (unc-51 like autophagy activating kinase 1), a mammalian serine/threonine kinase, is a key component of autophagy initiation complex and helps to induce all types of autophagy. Canonical autophagy is a process in which, through the interactions of a series of autophagy-related proteins, damaged organelles or misfolded proteins are engulfed by autophagosomes and then merged with lysosomes to be degraded. Thus, canonical autophagy is an important constituent part of the cellular “quality control.” Besides, accumulating evidence indicates that ULK1 exerts autophagy-independent effects in a cell-specific manner. For example, ULK1 facilitates neurite elongation through the regulation of endoplasmic reticulum (ER)–Golgi trafficking in neurons, stimulates phosphopentose pathway to help NADPH (nicotinamide adenine dinucleotide phosphate hydrogen) production, and acts as a duplex regulator in type I IFN (type I interferon) induced innate immune response. Considering the importance and diversity of ULK1 in various biological processes, this review aims to present a comprehensive overview of autophagy and non-autophagy related functions of ULK1 in a variety of human physiological, pathological, and disease processes.     

腐蚀对模块式钢结构选煤厂设备支架振动响应影响的测试及分析

选煤厂采用模块式钢结构作为设备支架,受设备使用及养护不当造成结构构件严重腐蚀,构件截面削弱,导致结构产生过大振动,通过对结构各层振动响应测试,得到各测点水平向及竖直向振动速度幅值。经分析得出腐蚀后对结构整体刚度影响程度,为后期采取措施及安全生产提供依据。