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Cobalt-chromium-molybdenum alloy (CoCrMo) and ceramic are the two most common materials for the femoral head in hip joint prostheses, and the acetabular liner is typically made from ultra-high molecular weight polyethylene (UHMWPE), highly cross-linked polyethylene (XLPE), or highly cross-linked polyethylene blended with Vitamin E (VEXLPE). The selection of suitable materials should consider both wear performance and cost-effectiveness. This study compared the wear rate between different friction pairs using a hip joint simulator and then recommended a suitable prosthesis based on the corresponding processing technology and cost. All wear simulations were performed in accordance with ISO 14242, using the same hip joint simulator and same test conditions. This study found that when using the same material for the femoral head, the XLPE and VEXLPE liners had a lower wear rate than the UHMWPE liners, and the wear rate of the XLPE liners increased after blending with Vitamin E (VEXLPE). There was no significant difference in the wear rate of XLPE when using a CoCrMo or ceramic head. Considering the wear rate and cost-effectiveness, a CoCrMo femoral head with an accompanying XLPE liner is recommended as the more suitable combination for hip prostheses.

The photochromic switching mechanism of 2,3-difurylmaleic anhydride (DFMA) is investigated by first-principles calculations. Based on the stable structures of the open-ring (O-DFMA) and closed-ring (C-DFMA) of the DFMA, the minimum energy path (MEP) and the configuration of transition states (TS-DFMA) between the O-DFMA and C-DFMA are found by using the nudged elastic band (NEB) method, the potential barriers of O-DFMA and C-DFMA are 24959 cm–1(3.0945 eV) and 23328 cm–1(2.8923 eV), respectively, indicating that the DFMA molecule may be a thermally bistable molecule. Along the molecular configuration corresponding to the MEP curve (i.e. ground state S0), the potential energy curves of the lowest 8 singlet excited states of DFMA are calculated. Among these energy curves, only the first electronic excited state (i.e. S1 state) has a minimum value in the transition state (TS-DFMA) configuration. Combined with the molecular orbital transitions and orbital images, the photochromic mechanism of DFMA can be described as follows (1) From C-DFMA to O-DFMA process: under the action of the laser with S1–S0 resonance transition wavelength, the C-DFMA transits from S0 to S1 state, and then deactivates along the S1 potential energy curve, until a cross jumping transition occurs at the TS-DFMA structure from S1 to S0 and finally the molecule along the S0 potentioal energy curve returns to the O-DFMA configuration, then the switching action from closed-ring to open-ring is completed. The S1 state potential energy curve drops monotonically in this switching process, implying that there will be no fluorescent radiation in this process. (2) From O-DFMA to C-DFMA process: under the action of the laser with S1–S0 resonance transition wavelength, O-DFMA transits from S0 to S1 state. From the O-DFMA to TS-DFMA structure, there is a relatively “flat” area in the potential energy curve of the S1 state, and it decreases significantly only when it is close to the TS-DFMA. This means that O-DFMA needs to be excited with some vibrational modes to pass through the “flat” region of S1 and approaching to the TS-DFMA configuration, and then DFMA de-excites from the S1 state potential energy curve along a monotonic decline and a cross jumping transition from S1 to S0 occurs in the TS-DFMA configuration, completing the switching action from open-ring to closed-ring. It is also precisely because of the flat region of the potential energy curve of the initial S1 state that this excitation and switching process is accompanied by fluorescent radiations. The photochromic mechanism of DFMA indicates that it is suitable for making fluorescent molecular switches.

In this paper, the silver paste was prepared by highly dispersed spherical silver powders with an average particle size of 0.85 um. The silver conductive thick films were printed on Al2O3 and dielectric layer by screen-printing, the dielectric layer had been heat-treated differently, one was dried, the other fired. The corresponding sintering behaviors, electrical and mechanical properties of silver films were investigated systematically. Besides, we made a chip resistor to test performance. The results show that the silver conducting film on fired dielectric is compact, uniform and defect-free, the resistivity and adhesion are 2.54 uΩ·cm and 20.3 N mm−2 respectively. With the increase of sintering times, the conductivity of silver films on the fired dielectric layer increases first and then decreases, while the adhesion increases continuously. We proposed that the diffusion quantity of glasses from the dielectric layer to the surface was the key step in the period of the properties of silver films. The silver film on the fired dielectric layer has better applications in the high current chip resistors.

A series of Ce3+/Tb3+ singly doped and Ce3+, Tb3+ co-doped Ca3GdNa(PO4)3F phosphors were synthesized via high temperature solid-state reaction in a reductive atmosphere. The crystal, luminescence properties, energy transfer mechanism and thermal stability of the samples were investigated in detail. The Ce3+ doped phosphors can be excited in the range from 250 to 330 nm. The Ce3+,Tb3+ co-doped phosphors exhibit characteristic emission of Ce3+ and Tb3+ simultaneously under the excitation of 301 nm. In addition, the energy transfer efficiency from Ce3+ to Tb3+ reaches as high as 78.6% when the doping amount of Tb3+ is 0.20. The mechanism of energy transfer between Ce3+ and Tb3+ ions is demonstrated to be a dipole−dipole interaction. The luminescence characteristics show that this phosphor can be a platform for modeling a new phosphor and application in the solid-state lighting field.

Based on the hot pressing method, the remote phosphor films are prepared by adding TiO2 particles into YAG:Ce and silicon binder, and then they are packaged into white light emitting diode (WLED) device with chip on board (COB) blue light source. The photo-chromic properties and mechanism are studied and calculated. Based on Mie theory and Henyey-Greenstein function, forward scattering is the main light scattering form of YAG:Ce phosphor powder, while the forward scattering intensity is close to the back scattering intensity of TiO2 particles. The emission spectral intensity and relative luminance of remote phosphor film change with increasing the concentration of TiO2 particles, and the optimum concentration is 0.966 g/cm3. Forward transmission intensity and back reflection intensity are calculated and analyzed, when the concentration of TiO2 is low, the forward transmission intensity of blue light is stronger than that of yellow light and the main transmission form is forward transmission, while the forward and backward intensity of yellow light are similar because of isotropy. With increasing the concentration of TiO2, the forward intensity of blue light gradually decreases, and the transmission intensity is lower than that of yellow light. The forward and backward intensity of yellow light reach their maxima when the TiO2 concentration is 0.966 g/cm3. The main reason for this phenomenon is that the increasing of the utilization ratio between blue light and transmission of yellow light is affected by the strong scattering ability of TiO2. Finally the WLEDs are packaged by remote phosphor films and COB blue light source, the luminous flux of WLED reaches 415.28 lm (at 300 mA and 9.3 V) at a concentration of 0.966 g/cm3, which is increased by 8.15% compared with the concentration in the case of no TiO2 mixing. Besides, the correlated color temperature changes from cool white 6900 K to warm white 3832 K gradually. Consequently, the adding of TiO2 particles can not only improve the emission intensity of remote phosphor film and the luminous flux of WLED, but also regulate the correlated color temperature.

Based on the electro-optical energy transfer process, the pseudo-spectral-luminous efficiency function (QD) of quantum dots (QDs) is introduced, the equations of chromaticity coordinates, luminous efficiency, and the QDs' mass of the white-light-emitting devices with CdSe, CuInS2 or CdS:Mn QDs are obtained, and the calculated results are in agreement with the experimental data. For a certain luminescent peak wavelength, when the full width at half maximum of the QD's photoluminescence becomes larger, the QD value becomes smaller while the chromaticity coordinates become more different from those of the corresponding monochromatic light. It is indicated that the color rendering index (CRI) of the devices is strongly dependent on the photoluminescent position and width of the QDs, and the CRI value can be increased towards 98 when a certain kind of CdS:Mn QDs is added into the traditional white-light LEDs.