The control of acoustic waves on a micro-scale is a critical issue in the development of micro-acoustic devices. In this paper, we demonstrate a locally resonant phononic crystal (PNC) for the control of acoustic waves on a micro-scale. The locally resonant phononic crystal is realized by periodically arranging cylindrical stubs on a silicon plate in a square lattice. Two types of acoustic microwaveguides, i.e., straight waveguide and mirrored “Z” shape waveguide, are designed based on the micro-phononic crystal. Numerical simulation shows that acoustic waves with frequencies in the bandgap range are compelled to propagate along the waveguides. Experimental results also confirm that the locally resonant PNC could effectively control the propagation of acoustic waves with frequencies in the bandgap range. The locally resonant phononic crystal in this paper is believed to be an ideal metamaterial for the acoustic wave control on a micro-scale.

Membrane with mesa silicon microstructure is a fundamental structure widely used in micro-electro-mechanical system. However, it could be plastically deformed during high-temperature manufacturing process under certain load. This paper characterizes plastic deformation of vacuum sealed membrane with mesa silicon microstructure during 1100 \(^{\circ }\)C microfabrication process. In order to study plastic deformation of membrane with mesa microstructures, microstructures with different dimensions are designed based on Von Mises yield criterion. Experimental results show that the plastic deformation is linear to diaphragm size and boss size. The effect of stiffness on plastic deformation is compared with the effect on elastic deformation. Plastic deformation is not only determined by stiffness but also by film thickness. The relationship between plastic deformation and Von Mises stress is further investigated. Plastic deformation and initial Von Mises stress shows a Boltzmann function relation.

In this paper, energy localization in line-defect resonator based on locally resonant phononic crystal (PnC) is experimentally studied. The defected resonator is realized by creating line defects on a two-dimension (2-D) silicon PnC. The silicon resonator was fabricated by micro machining process and tested by a combination of the fluid coupling method and Laser Doppler Vibrometer (LDV). Acoustic waves with frequency range from 7.19 MHz to 7.50 MHz are trapped in the cavity, and the corresponding resonant modes are observed in-situ. The measured quality (Q) factor of the resonator, which is 427 at its resonant frequency of 7.3 MHz, is smaller than the simulated ones (666 and 5135). The experimental results agree well with the simulation results that frequencies of the trapped acoustic waves of are mostly in the range of the phononic bandgaps. The locally resonant based PnC resonator in paper with 17 dB magnitude amplification, which is normalized with respect to the transmission of a freestanding silicon slab in the same frequency range, has great potential in energy harvesting or sound concentration.

The effects of rapid thermal anneal (RTA) on film thickness, refractive index and residual stress of low pressure chemical vapor deposited (LPCVD) silicon nitride films are experimentally investigated. With the increase of RTA time, film thickness decreases in an exponential way and refractive index increases. Both film thickness and refractive index reach a relatively stable value after 10min RTA process and higher RTA temperature leads to larger reduction in film thickness. Residual stress of Si–Si3N4 system monotonically increases with RTA time. Based on Maxwell viscoelastic model, a model which considers film densification and viscous flow simultaneously is obtained to quantitatively calculate the effect of RTA on residual stress. In the 900°C and 1000°C RTA process, film densification is dominated in the 60min RTA process and both the mechanisms are more active with the increase of annealing temperature.

In this paper, a silicon cavity-mode resonator based on locally resonant phononic crystal (PnC) is experimentally studied. The PnC resonator is realized by creating line defects on a two-dimension (2-D) silicon PnC. The silicon resonator was fabricated by micro machining process, and tested by a combination of the fluid coupling method and Laser Doppler Vibrometer. Two resonant frequencies (7.93MHz and 8.03MHz) were observed in the PnC resonator. The experimental results agree well with the simulated band structures of the perfect PnC and PnC resonator, that the resonant frequencies of the designed PnC resonator are in the range of the phononic bandgaps (PnBGs).

Single crystal silicon MEMS microstructures could be plastically deformed during high-temperature manufacturing process. In this paper, an iterative finite element simulation method based on Von Mises yield criterion is proposed to determine the plastic deformation of silicon microstructure. In the proposed method, the critical condition for plastic deformation is that the maximum Von Mises stress of the microstructure equals to the yield stress. Sculptured diaphragm microstructures with different dimensions are designed to verify the method. Plastic deformation of the structure is measured after the annealing process of 1100°C. The simulation value fits the experiment well and the average deviation between the simulation data and experimental data is 2.2%.

This paper demonstrates a phononic crystal based silicon acoustic waveguide for the controllable propagation of Lamb waves in several MHz range. Different from the former phononic crystal applied in MEMS, which is based on Bragg scattering theory, the phononic crystal employed in this paper is based on locally resonant theory, which could provide better confinement of the acoustic waves. The silicon waveguide was fabricated by micro machining process, and tested by a combination of the fluid coupling method and Laser Doppler Vibrometer. The experimental result shows a good agreement with our theory prediction, that the designed locally resonant phononic crystal could effectively confine the elastic waves with selected frequency range in the guiding zone. The locally resonant phononic crystal demonstrated in paper is a good candidate for the control of acoustic waves propagating in MEMS.

In this paper, characterization of megahertz Lamb waves in a silicon phononic crystal based asymmetry filter by laser Doppler vibrometer is demonstrated. The acoustic power from a piezoelectric substrate was transmitted into the silicon superstrate by fluid coupling method, and measured results show that the displacement amplitude of the acoustic wave in the superstrate was approximately one fifth of that in the piezoelectric substrate. Effect of the phononic bandgap on the propagation of Lamb wave in the silicon superstrate is also measured, and the result shows that the phononic crystal structure could reflect part of the acoustic waves back.

The objective of this paper is to understand the effects of 1100°C annealing on film thickness, refractive index and especially residual stress of low-pressure chemical vapor deposition (LPCVD) silicon nitride films. The annealing effect on Young's modulus of silicon nitride films is also discussed. For these purposes, a number of 1100°C furnace annealing processes in N2 atmosphere were carried out. With the increase of annealing time, film thickness decreases exponentially and correspondingly the refractive index increases. Both film thickness and refractive index reach a stable value after several times annealing. Due to the film densification and viscous flow, residual stress of Si–Si3N4 system increases in the first 10min annealing treatment and then decreases in the following annealing processes. Based on the Maxwell viscoelastic model, an improved model which considers film densification and viscous flow simultaneously is built to explain the effect of annealing process on residual stress.

Lithium-iron-phosphate glasses with compositions of (20 - x)Li2O center dot xZnO center dot 30Fe(2)O(3)center dot 50P(2)O(5) (x = 0-7.2) have been prepared. The influences of the amount of ZnO on the structure, physical and chemical properties, and crystallization behavior of the glasses were investigated using Fourier transform infrared spectroscopy, differential thermal analysis and X-ray diffraction techniques. The density of glass was measured according to the Archimedes principle. The chemical stability was evaluated based on the weight loss after the glass particles were boiled in water. The results indicate that Zn2+ ions cross-linked the phosphate chains by forming P-O-Zn bridges when 2 mol% of ZnO was added. When the amount of ZnO was further increased, [ZnO4] tetrahedra were formed and ZnO acted as a glass network former, integrating the phosphate glass network. The density, chemical stability and the activation energy of crystallization of the glasses increased with the amount of ZnO, whereas the glass transition temperature decreased. All thermally treated glasses showed surface crystallization with LiFeP2O7 as the crystalline phase. (C) 2011 Elsevier B.V. All rights reserved.

UV-visible Absorption and fluorescence of two cyanine dyes (PSPI and PSQI) in DMF were measured. Their acidichromism properties were investigated. The maximum Absorption peak of PSPI is at 328 nm with the pH=2,which shows colorless. With the increasing of pH value to 3,the maximum Absorption peak in the lower energy region is red shifted to 458 nm. These suggest that optical switch point is located between 2 and 3 of pH value. Moreover,the acidichromism of PSPI in the presence of β-CD is clearer than that of PSPI without β-CD.

Two new porphyrin derivatives,named (TPP)2-p and (TPP)2-n,respectively,have been synthesized and characterized by 1H NMR measurement. And their absorption and luminescent spectra have been measured in comparison with the reference,TPP-a. The hyperconjugation effects existing in (TPP)2-p and(TPP)2-n were found to affect absorption and fluorescence behaviors,resulting in their molar absorbance and emission intensity of(TPP)2-p and (TPP)2-n are twice more than the reference,TPP-a. In addition,the hyperconjugation has contribution to intermolecular charge-transfer and resulting increases the molecular transition moment from the excited-to the ground-state. Thus,(TPP)2-p and (TPP)2-n show larger molar absorbance (e) and higher fluorescence intensity (I) than the reference,TPP-a,however,the fluorescence quantum yields of(TPP)2-p and(TPP)2-n are reduced. Since (TPP)2-p and (TPP)2-n possess symmetric conformation,relative to the reference (TPP-a),their dipole moment differences ( ge) between the excited-state and the ground-state show smaller,which confirms by Lippert equation.

In this paper, we reported the synthesis of two new triphenylamine derivatives: 1,4-bis[-E-4-(N,N-diphenylamino)styryl]naphthalene (Np-G1) and 2,8-bis[-E-4-(N,N-diphenylamino) styryl]dibenzothiophene (ST-G1) and investigated the electroluminescence characteristics of the three-layer devices with Np-G1 or ST-G1 as emitting layer. The results have shown that introduction electron-acceptor group, naphthalene, into triphenylamine units, Np-G1 with linear geometric conformation can lower its LUMO level obviously and resulting facilitate electron injection and transport for the device. Thus, the three-layer device (ITO/TCTA/Np-G1/BCP /Mg:Ag) improved the electroluminescence properties the best, presenting the brightness of ∼10,000 cd/m2 and current efficiency of ∼3.0 cd/A. On the other hand, ST-G1 with V-shaped conformation containing dibenzothiophene linked triphenylamine groups cannot effectively decreased its LUMO level. As a result, ST-G1 has little contribution to the carrier recombination within itself.

The organic/inorganic hybrid chromophores containing octaphenylsilsesquioxane(POS) as core and aromatic Schiff base as periphery have been synthesized.Under the excitation of 140 femtosecond Ti:sapphire laser at 800nm pulses,intense frequency up-converted fluorescence emissions locating at 600nm for samples(3 and 4) were recorded.The DSC curves of both samples 3 and 4 show no obvious endothermal but exothermic process with peak at 377℃ for 3 and 284℃ for 4.These indicate that both multibranched chromophores are thermal stable enough to be used as the TPA material in devices application.

The synthesis of new triphenylamine-branching chromophores with dibenzofuran-core and dibenzothiophene-core was reported and the molecular two-photon absorption (TPA) enhancement via core effect and generation effect was investigated. Comparatively, the core effect shows more significant contribution to TPA enhancement than the generation effect. This is of greatly valuable since optimizing dendritic core is laborsaving in comparison with synthesizing dendrimers with high generation.

To test the expression of HER4 in non-small cell lung cancer (NSCLC) and elucidate the relationship between its over-expression and the clinical pathology of NSCLC.

Based on the extensive investigation on the Chinese literature on science and technology,the basic knowledge of Chinese ancestor about the crystal and related characters are summarized,especially for crystal morphology,symmetry and functional properties.From the data collected,it is seen that the knowledge on crystals of Chinese ancestor was abundant but only at superfial,resulting in the loshing of opportunity to develop modern crystallography.

The synthesis of new dendritic chromophores with dibenzothiophene as molecular focal point bearing multibranched triphenylamine unit at the periphery(named as ST-G2) was reported.The electroluminescence device(ITO/ TCTA/emitting layer /BCP/Mg∶Ag) based on 2,8-bis{E-4',4''-di-(E-4-(N,N-diphenylamino)styryl)-E-4-(N,N-diphenylamino)styryl}dibenzothiophene as emitting layer have been designed and prepared.Current efficiency,power efficiency,and brightness of the device have been measured.The brightness about 1000cd/m2 and the power efficiency of 0.2lm/W were observed.

Two novel, triphenylamine derivatives N-(4-(4-(diphenylamino)styryl)phenyl)acetamide and N-(4-(4-(bis-(4-(4-(diphenyl-amino)styryl)phenyl)amino)styryl)phenyl)acetamide were synthesized. The two-photon absorption of N-(4-(4-(bis-(4-(4-(diphenyl-amino)styryl)phenyl)amino)styryl)phenyl) was ∼17-fold greater relative to N-(4-(4-(diphenylamino)styryl)phenyl)acetamide. Linear absorption spectra, steady-fluorescence and time-resolved fluorescence spectra revealed that electron coupling originating from π-electron delocalization is responsible for the strong cooperative enhancement of TPA within the compounds. This is confirmed by the Lippert-Mataga equation.