Bi_2O_3晶须的水热合成研究

采用Bi（OH）3原料和KOH矿化剂,在120～220℃和0.5～10h的水热条件下,制备出单斜结构的α-Bi2O3;研究了原料种类、反应温度和保温时间对Bi2O3粉体形貌的影响,获得了分散性好、无团聚、长度4～70μm和长径比5～16的Bi2O3晶须.

Hybridization Effects Revealed by Angle-Resolved Photoemission Spectroscopy in Heavy-Fermion Ce2IrIn8

We utilize high-resolution resonant angle-resolved photoemission spectroscopy(ARPES)to study the band structure and hybridization effect of the heavy-fermion compound Ce2 IrIn8.We observe a nearly flat band at the binding energy of 7 meV below the coherent temperature Tcoh^40 K,which characterizes the electrical resistance maximum and indicates the onset temperature of hybridization.However,the Fermi vector and the Fermi surface volume have little change around Tcoh,which challenges the widely believed evolution from a hightemperature small Fermi surface to a low-temperature large Fermi surface.Our experimental results of the band structure fit well with the density functional theory plus dynamic mean-field theory calculations.

High-excited-state splitting and multimode vibrational coupling in Mn^(4+)-activated fluoride phosphor

Excited-states play a crucial role in the optical absorption and luminescence of solids and hence their accurate information is highly desired. Herein, we attempt to seize the excited-states information of Mn^(4+)ions in K_(2)SiF_(6) microcrystals via measuring and calculating their variable-temperature photoluminescence excitation(PLE) spectra. At cryogenic temperatures, an unpredicted splitting of the high-excited-state is observed. Moreover, the two-split high-excited-state levels are further revealed to primarily couple with the two hyperfine split modes of quasi-localized ν2 vibration in the distorted Mn-F_(6) octahedral configuration,whereas the coupling strengths are found to be substantially different from each other. The slightly split vibrational mode is firmly supported by the low-temperature Raman spectra. Jahn-Teller lattice distortion is believed to be responsible for the observed splitting of the electronic high-excited-state and the quasi-localized vibrational mode.

Valley piezoelectricity promoted by spin-orbit coupling in quantum materials

Quantum materials have exhibited attractive electro-mechanical responses,but their piezoelectric coefficients are far from satisfactory due to the lack of feasible strategies to benefit from the quantum effects.We discovered the valley piezoelectric mechanism that is absent in the traditional piezoelectric theories yet promising to overcome this challenge.A theoretical model was developed to elucidate the valley piezoelectricity in 2D materials as originating from the strong spin-orbit coupling.Consistent analytical and density-functional-theory calculations validate the model and unveil the crucial dependence of valley piezoelectricity on valley/spin splitting and hybridization energy.Up to 50%of electro-mechanical responses in our tested twodimensional systems are attributed to the valley piezoelectric mechanisms.Rational strategies including doping,passivation,and external strain are proposed to optimize piezoelectricity,with a more than 127%increase in piezoelectricity demonstrated by density-functional-theory simulations.The general valley piezoelectric model not only opens an opportunity to achieve outstanding piezoelectricity via optimizing intrinsic variables but also makes the large family of valley materials promising for piezoelectric sensing and energy harvesting.

Strong coupling between a plasmon mode and multiple different exciton states

Strong coupling between plasmons and multiple different exciton states(MESs)enables the creation of multiple hybrid polariton states under ambient conditions.These hybrid states possess unique optical properties different from those of their separate identities,making them ideal candidates for exploiting room-temperature multimode hybridization and multiqubit operation.In this study,we revealed the static spectral response properties of plasmon-MES strong coupling via a fully quantum mechanics approach.These theoretical predictions were experimentally demonstrated in plasmonic nanocavities containing two and three different exciton species.Additionally,the dynamical absorption processes of such strong coupling systems were investigated,and results indicated that the damping of the hybrid polariton states induced by the strong coupling could be markedly modulated by the acoustic oscillations from the plasmonic nanocavities.Our findings contribute a theoretical approach for accurately describing the plasmon-MES interactions and a platform for developing the high-speed active plasmonic devices based on multiqubit strong coupling.

Light-Programmed Bistate Colloidal Actuation Based on Photothermal Active Plasmonic Substrate

Active particles have been regarded as the key models to mimic and understand the complex systems of nature.Although chemical and field-powered active particles have received wide attentions,lightprogrammed actuation with long-range interaction and high throughput remains elusive.Here,we utilize photothermal active plasmonic substrate made of porous anodic aluminum oxide filled with Au nanoparticles and poly(N-isopropylacrylamide)(PNIPAM)to optically oscillate silica beads with robust reversibility.The thermal gradient generated by the laser beam incurs the phase change of PNIPAM,producing gradient of surface forces and large volume changes within the complex system.The dynamic evolution of phase change and water diffusion in PNIPAM films result in bistate locomotion of silica beads,which can be programmed by modulating the laser beam.This light-programmed bistate colloidal actuation provides promising opportunity to control and mimic the natural complex systems.

Radiation theory comparison for magnetoacoustic tomography with magnetic induction(MAT-MI)

Based on the principle of Lorentz force induced acoustic vibration, radiation theory comparison between acoustic point and dipole sources was conducted for magnetoacoustic tomography with magnetic induction(MAT-MI). It is proved that each acoustic source of MATMI is produced by the divergence of the magnetically induced Lorentz force, and the detected acoustic pressure is the integral of all diffraction sources inside the object.Wave clusters are produced by abrupt pressure changes at conductivity boundaries, and only the configurations in terms of shape and size of phantom models can be reconstructed. However, different from point source, positive and negative pressures are generated by the radiation pattern of dipole sources. Reverse vibration phases of wave clusters in collected waveforms and opposite polarities of borderline stripes in reconstructed images are produced at conductivity boundaries, representing the direction of conductivity changes. The experimentally collected waveforms and reconstructed images of the aluminum foil cylinder and cylindrical saline gel phantom model agree well with simulated results. The favorable results prove the validity of the radiation theory of acoustic dipole source and provide basis for further investigation of conductivity reconstruction for MAT-MI.

ZnO:Al Films Prepared by Reactive Mid-frequency Magnetron Sputtering with Rotating Cathode

Al-doped zinc oxide （ZnO：Al,AZO） films were deposited on glass substrates using a reactive mid-frequency （MF） magnetron sputtering process with rotating cathodes.The influence of deposition parameters on structural,electrical and optical properties of AZO films is investigated.It is observed that the rotating magnetron targets exhibited a sputtered metallic surface over a wider range,and there is no re-deposition zone between the racetracks.The films deposited at static deposition mode demonstrate more homogenous in thickness and resistivity across the target surface compared with conventional rectangular targets.The films deposited under the proper conditions show a regular cone-shaped grain surface and densely packed columnar structure.The minimum resistivity of 3.16×10-4 ·cm was obtained for the film prepared at substrate temperature of 150 C,gas pressure of 640 MPa and oxygen partial pressure of 34 MPa.

Noise transmission during the dynamic pattern formation in fly embryos

Background： Developmental patterning is highly reproducible and accurate at the single-cell level during fly embryogenesis despite the gene expression noise and external perturbations such as the variation of the embryo length, temperature and genes. To reveal the underlying mechanism, it is very important to characterize the noise transmission during the dynamic pattern formation. Two hypotheses have been proposed. The ＂channel＂ scenario requires a highly reproducible input and an accurate interpretation by downstream genes. In contrast, the ＂filter＂ scenario proposes a noisy input and a noise filter via the cross-regulation of the downstream network. It has been under great debates which scenario the fly embryogenesis follows. Results： The first 3-h developmental patterning of fly embryos is orchestrated by a hierarchical segmentation gene network, which rewires upon the maternal to zygotic transition. Starting from the highly reproducible maternal gradients, the positional information is refined to the single-cell precision through the highly dynamical evolved zygotic gene expression profiles. Thus the fly embryo development might strictly fit into neither the originally proposed ＂filter＂ nor ＂channel＂ scenario. The controversy that which scenario the fly embryogenesis follows could be further clarified by combining quantitative measurements and modeling. Conclusions： Fly embryos have become one of the perfect model systems for quantitative systems biology studies. The underlying mechanism discovered from fly embryogenesis will deepen our understanding of the noise control of the gene network, facilitate searching for more efficient and safer methods for cell programming and reprogramming, and have the great potential for tissue engineering and regenerative medicine.