The applications of lanthanide-doped upconversion nanomaterials are limited by unsatisfactory brightness currently. Herein, a general strategy is proposed for boosting the upconversion efficiency in ...Er
ions, based on combined use of a core-shell nanostructured host and an integrated optical waveguide circuit excitation platform. A NaErF
@NaYF
core-shell nanoparticle is constructed to host the upconversion process for minimizing non-radiative dissipation of excitation energy by surface quenchers. Furthermore, an integrated optical microring resonator is designed to promote absorption of excitation light by the nanoparticles, which alleviates quenching of excited states due to cross-relaxation and phonon-assisted energy transfer. As a result, multiphoton upconversion emission with a large anti-Stokes shift (greater than 1150 nm) and a high energy conversion efficiency (over 5.0%) is achieved under excitation at 1550 nm. These advances in controlling photon upconversion offer exciting opportunities for important photonics applications.
Research on the influencing mechanism between parenting styles and pro-social behavior still needs to be advanced. The purpose of the research is to examine how paternal rearing styles, empathy and ...psychological capital relate to the pro-social behaviors of Chinese lower-division undergraduate students. Four questionnaires were used to measure 488 Chinese lower-division undergraduate students. These were the Short-form Parenting Style Questionnaire in Chinese (S-EMBU-C), the Pro-Social Behavior Scale (Chinese version), The Interpersonal Response Pointer Scale (Chinese version), and the Positive Psychological Capital Questionnaire. The results found that: (1) Correlations between paternal rearing styles and empathy, psychological capital, and pro-social behavior of Chinese lower-division undergraduate students; (2) The mediating role of empathy and psychological capital between active paternal rearing styles and pro-social behavior was not significant; (3) Empathy and psychological capital mediated significantly between negative paternal rearing styles and pro-social behavior. The study fills gaps in previous research and guides schools and families, making it theoretically and practically significant.
Coherent ultraviolet light is important for applications in environmental and life sciences. However, direct ultraviolet lasing is constrained by the fabrication challenge and operation cost. Herein, ...we present a strategy for the indirect generation of deep-ultraviolet lasing through a tandem upconversion process. A core-shell-shell nanoparticle is developed to achieve deep-ultraviolet emission at 290 nm by excitation in the telecommunication wavelength range at 1550 nm. The ultralarge anti-Stokes shift of 1260 nm (~3.5 eV) stems from a tandem combination of distinct upconversion processes that are integrated into separate layers of the core-shell-shell structure. By incorporating the core-shell-shell nanoparticles as gain media into a toroid microcavity, single-mode lasing at 289.2 nm is realized by pumping at 1550 nm. As various optical components are readily available in the mature telecommunication industry, our findings provide a viable solution for constructing miniaturized short-wavelength lasers that are suitable for device applications.
Recently, research on path planning for the autonomous underwater vehicles (AUVs) has developed rapidly. Heuristic algorithms have been widely used to plan a path for AUV, but most traditional ...heuristic algorithms are facing two problems, one is slow convergence speed, the other is premature convergence. To solve the above problems, this paper proposes a new heuristic algorithms fusion, which improves the genetic algorithm with the ant colony optimization algorithm and the simulated annealing algorithm. In addition, to accelerate convergence and expand the search space of the algorithm, some algorithms like trying to cross, path self-smoothing and probability of genetic operation adjust adaptively are proposed. The advantages of the proposed algorithm are reflected through simulated comparative experiments. Besides, this paper proposes an ocean current model and a kinematics model to solve the problem of AUV path planning under the influence of ocean currents.
We propose a unified approach to fit simultaneously a set of atomic partial charges and polarizabilities of the polarizable model against the ab initio electrostatic potential (ESP) and ...polarizability. The polarizable model is represented with interactive atomic dipoles with distance-dependent attenuation. For the polarizable model employed in this study, the internal electric field on the polarization sites is fully turned on, and thus allows self-induced dipoles, which persist even for an isolated molecule/ion. By such treatment, the contribution of ESP stems not only from the partial charges but also from the self-induced dipoles, and the atomic partial charges and polarizabilities can be fitted simultaneously against ESP in a unified manner. The fitting with 1-ethyl-3-methylimidazolium (EMIM+) and nitrate (NO3 –), a prototypical organic cation and inorganic anion, respectively, that can form ionic liquid, demonstrates that allowance of the self-induced dipoles gives much better fitness. Moreover, test on the total dipole of an EMIM+/NO3 – ion pair shows that the agreement with the ab initio dipole is also much improved for the polarizable model, which highlights the importance of the polarization effects of ionic liquids.
To improve the oxidation resistance and alleviate the thermal stress of the HfB2-SiC-Si/SiC coatings for C/C composites, in-situ formed SiC whiskers (SiCw) were introduced into the HfB2-SiC-Si/SiC ...coatings via chemical vapor deposition (CVD). Effects of SiCw on isothermal oxidation and thermal shock resistance for the HfB2-SiC-Si/SiC coatings were investigated. Results showed that the SiCw-HfB2-SiC-Si/SiC coatings exhibited excellent oxidation resistance for C/C composites with only 0.88% weight loss after oxidation for 468 h at 1500 °C, which was markedly superior to 4.86% weight loss for coatings without SiCw. Meanwhile, after 50 times thermal cycling, the weight loss of the SiCw-HfB2-SiC-Si/SiC coated samples was 4.48%, which showed an obvious decrease compared with that of the HfB2-SiC-Si/SiC coated samples. The SiCw-HfB2-SiC-Si/SiC coatings exhibited excellent adhesion to the C/C substrate and had no penetrating cracks after oxidation. The improved performance of the SiCw-HfB2-SiC-Si/SiC coatings could be ascribed to the SiCw, which effectively relieved CTE mismatch and remarkably suppressed the cracks through toughening mechanisms including whiskers pull-out and bridging strengthening. The above results were confirmed by thermal analysis based on the finite element method, which demonstrated that SiCw could effectively alleviate thermal stress generated by temperature variation. Furthermore, the SiCw-HfB2-SiC-Si/SiC coating can provide a promising fail-safe mechanism during the high temperature oxidation by the formation of HfSiO4 and SiO2, which can deflect cracks and heal imperfections.
Mechanoluminescence (ML) featuring photon emission by mechanical stimuli is promising for applications such as stress sensing, display, and artificial skin. However, the progress of utilizing ML ...processes is constrained by the limited range of available ML emission spectra. Herein, a general strategy for expanding the emission of ML through the use of lanthanide emitters is reported. A lithium‐assisted annealing method for effective incorporation of various lanthanide ions (e.g., Tb3+, Eu3+, Pr3+, Sm3+, Er3+, Dy3+, Ho3+, Nd3+, Tm3+, and Yb3+) into CaZnOS crystals that are identified as one of the most efficient host materials for ML is developed. These doped CaZnOS crystals show efficient and tunable ML spanning full spectrum from violet to near infrared. The multicolor ML materials are used to create encrypted anticounterfeiting patterns, which produce spatially resolvable optical codes under single‐point dynamic pressure of a ballpoint pen.
Multicolor mechanoluminescence spanning the full spectrum from violet to near infrared is achieved, based on effective incorporation of a wide collection of lanthanide ions into CaZnOS crystals through a lithium‐assisted annealing method. Multicolor mechanoluminescent materials are used to create encrypted anticounterfeiting patterns, which produce spatially resolvable optical codes under mechanical excitation.
It is commonly believed that the exceptional sensitivity of mammalian hearing depends on outer hair cells which generate forces for amplifying sound-induced basilar membrane vibrations, yet how ...cellular forces amplify vibrations is poorly understood. In this study, by measuring subnanometer vibrations directly from the reticular lamina at the apical ends of outer hair cells and from the basilar membrane using a custom-built heterodyne low-coherence interferometer, we demonstrate in living mouse cochleae that the sound-induced reticular lamina vibration is substantially larger than the basilar membrane vibration not only at the best frequency but surprisingly also at low frequencies. The phase relation of reticular lamina to basilar membrane vibration changes with frequency by up to 180 degrees from ∼135 degrees at low frequencies to ∼-45 degrees at the best frequency. The magnitude and phase differences between reticular lamina and basilar membrane vibrations are absent in postmortem cochleae. These results indicate that outer hair cells do not amplify the basilar membrane vibration directly through a local feedback as commonly expected; instead, they actively vibrate the reticular lamina over a broad frequency range. The outer hair cell-driven reticular lamina vibration collaboratively interacts with the basilar membrane traveling wave primarily through the cochlear fluid, which boosts peak responses at the best-frequency location and consequently enhances hearing sensitivity and frequency selectivity.