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Multifunctional LiNbO3 material plays an important role in domain wall microelectronics and nonlinear optoelectronics. However, the material is hard and relatively inert, and hence is quite difficultly etched. A new oblique method to etch LiNbO3 memory cells at the surface of X-cut bulk crystals was proposed in this study. The process includes mask fabrication, oblique etching, and wet corrosion cleaning. The etching angle highly approaches 83° to achieve better polarization retention than others with etching angles of 0° and 70°. Meantime, the measured domain switching hysteresis loops become more symmetrical along the voltage axis than others with the presence of a strong imprint field. The horizontal electric field simulation along the polar Z axis exhibits the enhanced nucleating fields of the domains located at two edges of each memory cell in contact to Pt electrodes under the same applied voltage. The depolarization field was better screened in the memory with a higher etching angle. The new oblique method can improve the performance of the ferroelectric domain wall memory significantly.

Ion-exchanged glasses are widely used in optoelectronic devices due to its high strength and optical waveguide effects. The MgF2 films deposited on the ion-exchanged glasses and the ion-exchanged glasses bombarded by argon ions (100 eV) at 220 °C were investigated in the present work. The microstructure of MgF2 films and the structural and physico-chemical properties of the ion-exchanged glasses before and after deposition and bombardment were analyzed by grazing incident X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), electron probe micro analysis (EPMA), micro-Raman spectroscopy and surface stress meter. It is shown that MgF2 films exhibit a polycrystalline and microcolumnar structure. The peak of potassium ions concentration distribution in the ion-exchanged glasses, accompanied by outward diffusion of potassium ions, decreases and moves from glass surface to the inner part to different degrees during deposition and bombardment. The potassium ions concentration in the region near the surface of argon ion-bombarded glasses is almost the same as the MgF2-coated glasses. Furthermore, the position and intensity of Raman bands in the subsurface region of the ion-exchanged glasses show obvious changes before and after deposition and bombardment. The values of compressive stress and depth of layer in the MgF2-coated ion-exchanged glasses and the argon ion-bombarded ion-exchanged glasses are far away lower than that of its values obtained in the ion-exchanged glasses. Overall results have shown that variations of chemical composition, Raman bands and surface compressive stress in the exchanged region indicate subsurface modification of the ion-exchanged glasses induced by deposition and bombardment, which provide useful information for the use of the ion-exchanged glasses in further.

Objectives The purpose of this study was to estimate the fatigue life of premolars restored with two dental ceramics, lithium disilicate (LD) and polymer infiltrated ceramic (PIC) using the numerical method and compare it with the published in vitro data. Methods A premolar restored with full-coverage crown was digitized. The volumetric shape of tooth tissues and crowns were created in Mimics®. They were transferred to IA-FEMesh for mesh generation and the model was analyzed with Abaqus. By combining the stress distribution results with fatigue stress–life (S–N) approach, the lifetime of restored premolars was predicted. Results The predicted lifetime was 1,231,318 cycles for LD with fatigue load of 1400 N, while the one for PIC was 475,063 cycles with the load of 870 N. The peak value of maximum principal stress occurred at the contact area (LD: 172 MPa and PIC: 96 MPa) and central fossa (LD: 100 MPa and PIC: 64 MPa) for both ceramics which were the most seen failure areas in the experiment. In the adhesive layer, the maximum shear stress was observed at the shoulder area (LD: 53.6 MPa and PIC: 29 MPa). Significance The fatigue life and failure modes of all-ceramic crown determined by the numerical method seem to correlate well with the previous experimental study.

We have successfully synthesized a multilayer-structured composite based on a combination of polydopamine (PDA)-coated silver nanoparticles (Ag@PDA) and silver nanowires (AgNWs@PDA) using a flexible and rapid method. We incorporated the structure into polyvinyl alcohol (PVA) polymer to enhance thermal conductivity and dielectric properties of nanocomposite films. Compared with Ag@PDA/PVA and AgNWs@PDA/PVA films, the use of multilayer-structure facilitated increased thermal conductivity and reduced permittivity of the nanocomposite film. The maximum thermal conductivity of composite with 10 wt% filler loading was increased to 3.63 W/mK, which is an enhancement by nearly 20 times compared with the use of neat PVA matrix. The relative permittivity and dielectric loss were about 6.65 and 0.024 at 1 MHz, respectively. We discussed the underlying mechanisms in an effort to optimize the structure for polymer matrix nanocomposites.

Objective Numerous bond strength tests have been performed on dental adhesion experiments. Yet, the validity of these bond strength tests is controversial due to the name ( e.g. , “shear” or “tensile”) may not reflect to the true and complete stress situation, i.e. , assumed uniform shear or uniaxial tensile conditions. Thus, the aim of this study was to simulate and compare the stress distribution of and between shear bond strength (SBS), tensile bond strength (TBS), mold-enclosed shear bond strength (ME-SBS) and de novo lever-induced mold-enclosed shear bond strength (LIME-SBS) tests. Methods 3-Dimensional finite element method (FEM) was used on the dental resin-bonded surfaces ( i.e. , titanium alloy, dentine and porcelain) interphased with adhesive layer (thickness 5 μm) to simulate the mechanical tests. For ME-SBS, both polycarbonate and stainless steel molds were used. For LIME-SBS, stainless steel levers and molds with lengths of 3 mm, 6 mm, 12 mm, 15 mm and 18 mm were used. The applied loads on these models were 50 N, 100 N and 200 N. Results De novo LIME-SBS test was the most optimal configuration to evaluate “shear” bond strength of adhesive in regards to providing significantly high and uniform shear stress as well as eliminating tensile stress at the interface. The conventional SBS test created very high tensile stress at the load area, whereas the TBS created optimal tensile stress but shear stress indeed co-exist. The ME-SBS test could also eliminate some of the tensile stress. Similar stress distributions pattern appeared on the Ti-adhesive models, the dentine-adhesive models and porcelain-adhesive models. Significance None of the bond strength tests could give purely “shear” or “tensile” bond strength, but LIME-SBS seems to be the best model to evaluate the bond strength under true “shear” mode.

One of the most important aspects in the field of dentistry is adhesion. Adhesion can be enhanced through different mechanisms, most commonly by chemical and mechanical modifications of dental material surfaces. One example of chemical adhesion utilizes primers or bonding agents containing coupling agents. Universal primers which are (mainly organophosphate-based monomers) and silane coupling agents are the most effective and most widely used for unifying dissimilar materials. Other than improving adhesion, Silanes have many other applications in dentistry. They have been found also to enhance the mechanical properties of materials either by adhesion or by becoming a constituent of dental materials itself. Universal primers, on the other hand, are utilized in bonding between different dental materials such as ceramics, metals, alloys, as well as to resin composites. Unfortunately, these primers, coupling agents, and bonding agents have, in general, poor hydrolytic stability. They are susceptible to humid oral environment, which invariably render them potentially unstable in the humid oral environment as saliva is always present. Improving their hydrolytic stability should therefore result in stronger adhesion for dental materials and dental prosthesis with a better clinical survival rate.

The aim was to evaluate in vitro the feasibility of using three silane coupling agents/blends: (I) 1.0 vol % 3-acryloxypropyltrimethoxysilane (ACPS), (II) a novel silane system: 1.0 vol % 3-acryloxypropyl trimethoxysilane + 0.5 vol % bis-1,2-(triethoxysilyl)-ethane (ACPS + BTSE), and (III) a novel silane system: 1.0 vol % 3-acryloxypropyl trimethoxysilane + 0.5 vol % bis[3-(trimethoxysilyl)propyl]amine (ACPS + BTMA), as adhesion promoters on the repair of dental silver amalgam with a resin composite with respect to various artificial ageing conditions. Two hundred and forty flowable composite resin stubs were bonded to freshly prepared dental silver amalgam discs. The discs were silica-coated and silanized with the 3 silanes. Another 20 resin stubs were bonded to the amalgam surface without any silica-coating or treated with silica-coating only. Then, the specimens were randomly distributed into 8 sub-groups for initial (control), thermal cycling (1000, 3000 and 6000) and DI water storage (1 day, 1 week, 1 month and 3 months). Shear bond strength (SBS) test was measured using a universal testing machine with a 1 mm/min cross-head speed. Failure modes were classified and SEM images were obtained. Two-way ANOVA was used to detect statistical differences. The initial SBS of the control groups were (Mean/SD) 20.2 ± 3.3 MPa for ACPS only, 16.6 ± 3.9 MPa for ACPS + BTMA, and 19.5 ± 3.3 MPa for ACPS + BTSE. A decreasing trend of SBS was observed by using the current artificial ageing methods, and ACPS and ACPS + BTSE produced statistically higher bond strengths compared to ACPS + BTMA under thermal cycling (p

During plasma spray-physical vapor deposition (PS-PVD) of yttria-stabilized zirconia (YSZ) coatings, evaporation of the YSZ powder is essential, but quite difficult when using a commercial

Aluminum (Al) and Copper (Cu) have been used in graded density impactors. Al-Cu composites with different compositions have been prepared by hot pressing sintering. Intermetallic compounds were produced when the temperature was above 723 K, while they can’t be found at the temperature of 723 K. The relative density of Al-Cu composites from pure Al to pure Cu consolidated at 723K all exceeded 98.5%. The optimum sintering conditions were then determined to sintering temperature of 723 K, uniaxial pressure of 100 MPa, and duration time of 2 h. Al and Cu were mixed homogeneously and well compacted, and no obvious pores were found. The thickness of diffusion layer between Al and Cu was very thin, only about 0.6 μm. The wave impedance values increased almost linearly from 16.98×106to 40.66×106kg/m2·s with increasing Cu content in Al-Cu composite from 0 to 100 vol.%, which was well consistence with the values calculated according to the rule of mixtures. The elastic modulus of different compositions matched well with the theoretical model of Voigt and Reuss. Highly densified Al-Cu composites without intermetallic compounds were successfully prepared using hot-pressure sintering, which was the basis of fabricating Al-Cu system graded density impactors.

Monomers based on 2,1,3-benzothiadiazole bearing solubilizing side chains have been synthesized in high yields over four steps from readily available starting materials. A multistep synthesis of the electron-poor 5,6-bis (heptyloxy) benzo [[1,2,thiadiazole are presented. The new deficient acceptor has good solubility in organic solvents to permit an appropriate coating process.

Heterocyclic oligomer based on BBT bearing solubilizing side chains have been synthesized in high yields over six steps from readily available starting materials. This approach offers a much milder, shorter, and more efficient route to BBT derivatives than current methods. This unit can then be used in the synthesis of low bandgap materials via palladium-catalyzed coupling reactions.

Heterocyclic monomer based on 2,1,3-benzothiadiazole bearing solubilizing side chains have been synthesized in high yields over three steps from readily available starting materials. The alkyl side chain in the 4-position of both thiophene rings gives the material mononer a good solubility.

Heterocyclic monomers based on 2,1,3-benzothiadiazole bearing solubilizing side chains have been synthesized in high yields over four steps from readily available starting materials. The new dificient acceptor has good solubility in organic aolvents to permit an appropriate coating process. Two soluble donor-acceptor π-conjugated oligomers comprising electron-rich thiophenes the electron-deficient EDOBT have been carefully investigated.

In order to accurately estimate the anti-penetration capacity of yaw-inducing bursting layer with irregular barriers on surface impacted by projectile, the theoretical model of attack angle and angular velocity for projectile impacting on irregular barrier was achieved according to the macroscopic relation of contact force versus contact time, in which the main factors such as the relative geometrical characteristics of projectile and irregular barrier, material property and impact velocity of projectile influencing on yaw-inducing effectiveness were considered. On the basis of considering synthetically the influences of attack angle, impact velocity, impact angle of projectile and uncontrolled free surface of target, the theoretical formulation of penetration depth for bursting layer with irregular barriers on surface impacted by projectile was presented by expressing the stress of an optional point on the nose of projectile according to the relation of stress versus velocity. The theoretical results indicate that in the case of oblique impact embodying effect of attack angle, the penetration depth is reduced with the increase of impact angle, attack angle or angular velocity, and penetration trajectory is also deflected obviously. The effectiveness of angular velocity influencing on penetration depth is increased with impact velocity increasing. The theoretical results are in good agreement with test data for low impact velocity.

A synthetic approach to synthesize 4,8-Dibromobenzo-[1,2-c;4,5-c’] bis[1,2,5]thiadiazole from a common precursor 2,1,3-Benzothiadiazole is reported. This unit can then be used in the synthesis of low bandgap materials via palladium-catalyzed coupling reactions.

Heterocyclic monomers based on 2,1,3-benzothiadiazole bearing solubilizing side chains have been synthesized in high yields over four steps from readily available starting materials. A multistep synthesis of the electron-poor 6, 7-dihydro-1, 4-dioxino-[2, 3-f][2,1,3]-benzothiadiazole are presented. The new dificient acceptor has good solubility in organic aolvents to permit an appropriate coating process.

The bearing capacities of one-way reinforced concrete beams with elastic supports are investigated in this paper. According to the nonlinear characteristics of the beams, the basic equations based on plastic theory of concrete are derived by considering the in-plane force effects that aroused by the constraints of supports when the beams deforming. It is indicated that the calculation results are in good agreement with experimental datum, and the influences of different supports on the bearing capacities of the beams are quantitatively given for the first time.

We explored a novel 3D sandwich structure of fillers in the polymer matrix to enhance thermal conductivity. A variety of fillers in the polymer matrix play a significant role in the physical properties of the composite. Fillers containing particle and line structures are popular, and enhance the thermal and electrical conductivities. Therefore, filler-based matrix network improves conductivity. We propose a sandwich structure consisting of hybrid graphite nanosheets (two dimensions), and silver nanowires (AgNWs) (one dimension), to create a 3D sandwich structure of polyimide matrix with improved thermal conductivity. Surface treatment of graphite and silver nanowires were conducted to reduce the dielectric constant of the composite. We designed the filler of 20 wt% resulting in a high thermal conductivity of 3.21 W m−1 K−1 with 15% C@SiO2 and 5% AgNWs@SiO2 filler loading. The novel combination and structure markedly enhanced the thermal conductivity of the composite.