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This study was evaluating how three desensitizing toothpastes used at home influence the effect associated with desensitizing agents after application in the clinic. Fifty dentine disks measure it permeability and 32 dentine disks with similar permeability levels were selected. Following Dental desensitizer treatment, dentine disks were randomly divided into three subgroups (n=10) that received applications of three toothpastes, respectively. The permeability (Lp) of each specimen was measured after each treatment. One specimen was selected from each group for scanning electron microscopy (SEM) observation. After each treatment, the Lp values decreased significantly for each group (p 0.05). After using the Dental desensitizer, Sensodyne, Crest and Colgate desensitizing toothpastes both can continued to reduce the permeability of the dentine disk, and no significant differences were found amongst them.

Absorbable magnesium (Mg) materials are promising for medical implant applications. However, their corrosion rate and potential toxicity remain a challenge. Herein, a photo-cross-linked coating with suitable durability and unique surface-eroding behavior for enhancement of anticorrosion property and cytocompatibility of AZ31 Mg alloy was developed. The biodegradable allyl-functional polycarbonate, poly[(5-methyl-5-allyloxycarbonyl-1,3-propanediol carbonate)

We demonstrated the first, 5th order ~790-805 nm edge-emitting semiconductor distributed feedback Bragg reflection waveguide laser with a side-mode suppression ratio of 49 dB and a corresponding linewidth of 207 kHz.

Removal of antibiotics detected in wastewater or natural aquatic systems by regular municipal treatment is challenging. Photocatalysis is considered to be the most well-known and green strategy for such removal. However, the catalytic efficiency is restricted by UV radiation dependence, fast electron-hole recombination, and low porosity/surface area of the photocatalyst. In this study, we have developed a highly porous anatase TiO2-polymethylsilsesquioxane (PMSQ) aerogel with nonmetal carbon dopant, which can simultaneously enhance the adsorption ability and visible light photo-activity. And tetracycline hydrochloride (TCH) was selected as a model antibiotic. A high surface area (747 g cm−3) C-TiO2-PMSQ aerogel can remove 91% TCH within 180 min under visible light. But the removal needs to be in an isopropyl alcohol/water co-solvent, due to the intrinsic hydrophobicity of PMSQ. After a heat treatment under 400°C, the surface area of C-TiO2-PMSQ aerogel decreases to 618 g cm−3, and the sample loses its hydrophobicity, the removal of TCH can be in aqueous condition and the efficiency increases to 98%. Moreover, both catalysts can be recycled 7 times and still maintain high removal efficiency (85 and 64% remained for hydrophobic and hydrophilic gels, respectively).

Focus stacking is a promising computational technique to extend depth of field by fusing images focused at different focal planes. However, existing focus stacking methods could not cope with the blurring-effect problem produced in structural edges, where depth values change abruptly. In this work, we firstly extract structural edges robustly by designing Des(depthmap-based extraction of structural edges)-ResNet. Then we propose a novel convolutional neural network (BEF-CNN) to restore blurring-effect-free image patches in order to enhance all-in-focus performance. To the best of our knowledge, it is the first work to utilize CNN to generate all-in-focus image directly instead of pixel-to-pixel correspondence with depthmap. Experimental results validate that our proposed algorithm has achieved best all-in-focus image while keeping the accuracy of depthmap.

The aim of this study was comparing different lasers with conventional non-surgical treatment (CNT) for the management of peri-implantitis, regarding probing depth (PD), plaque index (PLI), clinical attachment level (CAL), and sulcus bleeding index (SBI). Randomized controlled trials (RCTs) on different lasers and CNT for peri-implantitis were searched. Pairwise and network meta-analyses were performed to analyze the PD, PLI, CAL, and SBI outcomes. The risk of bias, evidence quality, statistical heterogeneity, and ranking probability were also evaluated. Eleven studies were included in this study, involving three types of lasers. Diode + CNT had significantly superior efficacy to CNT alone, regarding PD reduction, while Er:YAG + CNT had significantly superior efficacy than CNT in terms of the PLI, CAL, and SBI. The highest probability of being most effective for PD was diode + CNT (49%), while Er:YAG + CNT had the highest probability of improving the PLI, CAL, and SBI (66%, 53%, and 79%, respectively). Diode + CNT was significantly superior for PD management in peri-implantitis compared with CNT alone, while Er:YAG + CNT significantly improved the PLI, CAL, and SBI. Therefore, Er:YAG + CNT might be recommended methods considered for management of peri-implantitis.

We report a potential example of using surface functionalization to provide magnesium alloys (Mg–Ca) with controlled release and corrosion resistance properties. A key feature of this approach is to treat the Mg–Ca surfaces with nanoparticles via electrodeposition that can stably load and controllably release bioactive agents or drugs. These photo-cross-linkable and nano-scale particles were prepared by the self-assembly of an amphiphilic poly(γ-glutamic acid)-g-7-amino-4-methylcoumarin (γ-PGA-g-AMC) with encapsulation of a vitamin; moreover, the size and morphology of the resulting particles were studied. Fluorescence microscopy analysis indicated that Vm was effectively incorporated into the γ-PGA-g-AMC particles. Scanning electron microscopy (SEM) images showed that the colloidal particles could be uniformly electrodeposited on the Mg–Ca alloys. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the successful anchoring of the particles. After the surface electrodeposition of self-assembled colloidal particles, the in vitro degradation results show that deposition of the particles was found to reduce the degradation rate of the magnesium alloys; moreover, the vitamin was controllably released for up to 20 days. Furthermore, the Mg–Ca substrate functionalized with colloidal particles containing a vitamin significantly promoted the attachment, proliferation and spread of NIH-3T3 normal cells. The entire strategy may be used in various medical devices to create coatings for improved biomedical performance.

Single mode Bragg ring lasers, with SNR > 30 dB have been demonstrated. Efficient, self-pumped, broadband phase-matching of χ(2) nonlinearity is observed, offering self-pumped parametric C-band conversion >40 nm with efficiency of 142% W_1cm_2.

Photo-crosslinking copolymer Poly (2-Hydroxyethyl methacrylate-co-2-(Dimethylamino) ethyl methacrylate-co-7-hydroxy-4-methylcoumarin methacrylate) (PHDC)) was first synthesized by free radical polymerization of 7-hydroxy-4-methylcoumarin methacrylate (CA), 2-Hydroxyethyl methacrylate (HEMA) and 2-(Dimethylamino)ethyl methacrylate (DMA). Then, the copolymers were self-assembled into colloidal particles and immobilized on the NiTi alloy by a simple one-step electrophoretic deposition. After irradiation, a photo-crosslinked coating was obtained. The structure and morphology were characterized by OCA and SEM. The copolymer coatings could significantly decrease the release of nickel ions into the environment and reduce cytotoxicity inducing by nickel ions according to immersion experiment. Meanwhile, the coatings have good cytocompatibility. This work provides a simpler polymer coating method to inhibit the release of toxic ions by inducing ion adsorption with certain molecular structures, which have potential for biomedical applications such as artificial bone and bone fixation device.

In this paper, some different types of epoxy electrical conductive adhesive (ECA) are prepared and investigated. Flake silver, spherical silver and the mixture of them are employed to fabricate ECA samples, respectively. With different percentage of filler loading, the morphology, adhesion, hardness, resistivity and differential scanning calorimeter (DSC) test of the silver filled ECA samples are compared and analyzed. By comparing the samples, it is found that the adhesion do not change a lot from each other. While in terms of hardness and resistivity, flake silver shows a better performance than spherical silver. The scanning electron microscopy figures of the ECA samples reveals that the mixed silvers have a better filler distribution and form a more dense conductive network than the single component—flake silver or spherical silver. Furthermore, when the ratio of flake silver to spherical silver reaches a suitable value, the ECA achieves the optimum electrical conductivity. Finally, the DSC test result shows the appropriate curing temperature for the ECAs.

In this paper, we report on the utilization of a novel background-free approach for trace gas sensing. The classical collocation of wavelength modulation spectroscopy and phase sensitive detection is replaced by asynchronous double beam structure in which a balanced amplified photodetector is introduced. Via a beam splitter, the laser beam passing through the gas medium is divided into the real-time and the delayed branches. An optic fiber delay line is taken to create a time-delay between the separated branches, and the following differential detection yields the first derivative of absorption spectrum that is equivalent to the first harmonic in wavelength modulation spectroscopy. By means of the straightforward method, the quantitative analysis of gas is performed without the disturbance that is caused by optical intensity modulation. The gas sensor is validated using ammonia and nitrogen mixture in a laboratory controlled environment (296 K in temperature and 1.01e5 Pa in total pressure). In the case of an absorption path with the effective length of 15.4 cm, the detection limit of 6.4 ppm is predicted from the assumption that the signal is weakened to be equal with the noise. Absorption spectroscopy for 500 ppm ammonia is recovered by integrating the output of balanced photodetector.

Purpose Cavitation inside pumps affects not only the steady state fluid flow, but also the unsteady or transient characteristic of the flow. However, cavitation inside pumps under transient processes is difficult to predict when the influence of the pipelines system is considered. In this paper we present a simulation method applied to a centrifugal pump and its related pipeline to analyze the induced unsteady cavitation phenomenon during the startup process. Design/methodology/approach In order to effectively predict transient processes of a pump and its pipeline system, the simulation method uses a coupled 1D and 3D scheme, which reduces the simulation cost. The simulation of the startup process of a centrifugal pump in a closed-loop pipeline system with and without cavitation has been performed to verify the proposed method. Findings The evolution of the pressure and flow rate obtained with the simulation method agrees well with the experimental results. It is found that the mass flow rate at the pump inlet and outlet is highly related to the cavitation vapor volume and that the pressure at the outlet of the impeller is greatly influenced by the discharge. Originality/value The 1D-3D coupling simulation method used in this paper is proven to be highly accurate, efficient and can be used to solve transient processes combined with cavitation or other complex phenomena.

This study assessed the potential of porous zirconia ceramic as an alternative to dentin via an in vitro dentin barrier cytotoxicity test. The permeability of dentin and porous zirconia ceramic was measured using a hydraulic-conductance system, and their permeability was divided into two groups: high and low. Using an in vitro dentin barrier test, the cytotoxicity of dental materials by dentin and porous zirconia ceramic was compared within the same permeability group. The L-929 cell viability was assessed by MTT assay. The mean (SD) permeability of the high and low group for dentin was 0.334 (0.0873) and 0.147 (0.0377) μl min−1 cm−2 cm H2O−1 and for zirconia porous ceramic was 0.336 (0.0609) and 0.146 (0.0340) μl min−1 cm−2 cm H2O−1. The cell viability of experimental groups which are the low permeability group was higher than that of the high permeability group for both dentin and porous zirconia ceramic as a barrier except for Maxcem Elite™ by porous zirconia ceramic. There was no significant difference between dentin and porous zirconia ceramic in cell viability, within either the high or low permeability group for all materials. The SD for cell viability of the porous zirconia ceramic was less than that of the dentin, across all materials within each permeability group, except for Maxcem Elite™ in the high permeability group. Porous zirconia ceramic, having similar permeability to dentin at the same thickness, can be used as an alternative to dentin for in vitro dentin barrier cytotoxicity tests. In vitro dentin barrier cytotoxicity tests when a standardized porous zirconia ceramic was used as a barrier could be useful for assessing the potential toxicity of new dental materials applied to dentin before applying in clinical and may resolve the issue of procuring human teeth when testing proceeds.

Novel properties and applications of multilayered nanowires (MNWs) urge researchers to understand their mechanical behaviors comprehensively. Using the molecular dynamic simulation, tensile behaviors of Ti/Ni MNWs are investigated under a series of layer thickness values (1.31, 2.34, and 7.17 nm) and strain rates ( 1.0 × 10 8 s − 1 ≤ ε . ≤ 5.0 × 10 10 s − 1 ). The results demonstrate that deformation mechanisms of isopachous Ti/Ni MNWs are determined by the layer thickness and strain rate. Four distinct strain rate regions in the tensile process can be discovered, which are small, intermediate, critical, and large strain rate regions. As the strain rate increases, the initial plastic behaviors transform from interface shear (the shortest sample) and grain reorientation (the longest sample) in small strain rate region to amorphization of crystalline structures (all samples) in large strain rate region. Microstructure evolutions reveal that the disparate tensile behaviors are ascribed to the atomic fractions of different structures in small strain rate region, and only related to collapse of crystalline atoms in high strain rate region. A layer thickness-strain rate-dependent mechanism diagram is given to illustrate the couple effect on the plastic deformation mechanisms of the isopachous nanowires. The results also indicate that the modulation ratio significantly affects the tensile properties of unequal Ti/Ni MNWs, but barely affect the plastic deformation mechanisms of the materials. The observations from this work will promote theoretical researches and practical applications of Ti/Ni MNWs.

As one of the most potentially ideal carriers of single-atom catalysts (SACs), two-dimensional materials have been widely concerned by researchers. In this work, the electronic properties and electrocatalytic activity of precious metals (PM) adsorbed silicene are studied based on density functional theory (DFT). The results show that Ru-, Rh-, Pd-, Os-, Ir-, and Pt-adsorbed silicene at the H-site are more stable. Secondly, From the comparative analysis of the adsorption energy and free energy of the hydrogen evolution reaction (HER) intermediates and oxygen evolution reaction (OER) intermediates of the stable adsorption systems, it can be concluded that the Ru, Rh, and Ir adsorption systems can promote the hydrogen evolution reaction (HER) process, while the Rh adsorption system has good oxygen evolution reaction (OER) activity. Besides, the electronic properties of precious metals (PM) adsorbed silicene are also discussed. Our theoretical studies indicated that silicene supported precious metals (PM) have good electrocatalytic performance, which could contribute to the application of silicene in electrocatalysis in the future.

Regulating orbital properties of two-dimensional (2D) materials has received tremendous interest. Here, we propose theoretically a new class of 2D materials XBi (X = Si, Ge, Sn, and Pb) with metal monochalogenides structure to host tunable orbital properties. As an example, the SnBi system is mainly discussed. It has found that spin-orbit coupling (SOC) transforms the electronic properties of SnBi from semiconductor into metal, and the external strain can lead to a novel Dirac electronic state. Surface chemical-decoration is confirmed to be an effective way to obtain Bi-pz orbital filtering effect and p-p orbital inversion, which may be realized through PbTe-based heterostructure and quantum-well in experiment. Particularly, the orbital regulation can give rise to fascinating Rashba spin-splitting in H-SnBi single-layer and PbTe/SnBi heterostructure. These findings provide a new class of 2D materials to explore orbital interaction.

To study the influence of fuel temperature on performances of biodiesel engine, combustion and emission performances of biodiesel engine at different fuel temperatures are tested and studied. It is found with the increase of fuel temperature, combustion pressure and instantaneous heat release rate curves leave far away from the top dead center and at high loads the combustion delays obviously; peak combustion pressure and peak instantaneous heat release rate decrease and at high loads the reduction increases; the backward combustion increases; at 1500 r/min, compared with 25 °C, NO X emissions of biodiesel at 40 °C and 55 °C averagely decrease by 7.6% and 9.1%, but smoke emissions averagely increase by 29.1% and 54.1%. Results indicate that fuel temperature has important influence on performances of biodiesel and it can be selected as a basic parameter to control the combustion and emission of biodiesel.

A new biodegradable nanocomposite coating to control the biocompatibility and anticorrosion property of Mg is reported in this work. The key feature of this strategy is to equip the Mg surfaces with poly( γ -glutamic acid)g -7-amino-4-methylcoumarin/hydroxyapatite ( γ -PGAg -AMC/ HA) hybrid nanoparticles via electrophoretic deposition in ethanol. The microstructures of the resulting nanocomposite coating are characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The results of standard electrochemical measurements along with immersion tests indicate that the nanocomposite coating has preferable in vitro degradation and corrosion resistance behavior than bare Mg. In addition, cytocompatibility is conducted using NIH3T3 cells and the coated sample shows better cell viability and cell adhesion than pure Mg substrate over the whole incubation period. The favorable anticorrosion behavior and cytocompatibility of the nanocomposite coating suggest that the newly developed γ -PGAg -AMC/ HA biodegradable nanocomposite coating may have a potential to improve the biological performance of Mg-based biomedical implants.

A novel biomedical coating was prepared from self-assembled colloidal particles through direct electrodeposition. The particles, which are photo-cross-linkable and nanoscaled with a high specific surface area, were obtained via self-assembly of amphiphilic poly(γ-glutamic acid)-g-7-amino-4-methylcoumarin (γ-PGA-g-AMC). The size, morphology, and surface charge of the resulting colloidal particles and their dependence on pH, initial concentrations, and UV irradiation were successfully studied. A nanostructured coating was formed in situ on the surface of magnesium alloys by electrodeposition of colloidal particles. The composition, morphology, and phase of the coating were monitored using Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and X-ray diffraction. The corrosion test showed that the formation of the nanostructured coating on magnesium alloys effectively improved their initial anticorrosion properties. More importantly, the corrosion resistance was further enhanced by chemical photo-cross-linking. In addition, the low cytotoxicity of the coated samples was confirmed by MTT assay against NIH-3T3 normal cells. The contribution of our work lies in the creation of a novel strategy to fabricate a biomedical coating in view of the versatility of self-assembled colloidal particles and the controllability of the electrodeposition process. It is believed that our work provides new ideas and reliable data to design novel functional biomedical coatings.

A new method of mechanical vibration assisted induction heating hot-pressing was proposed. A set of apparatus was developed to perform the forming of mechanical vibration assisted induction heating hot-pressing. A series of experiments of induction heating temperature characteristics of different kinds of powder was carried out, such as Fe powder, Al powder and SiC powder. The results show that different kinds of powder reach different equilibrium temperatures and have different temperature characteristics under the same condition of setting temperature and cyclic heating times. SiCp/Al composites were prepared by induction heating and vibratory forming and observed by metallographic microscope. It turns out that completely dense and homogeneous powder metallurgy compaction is compacted and sintered at the same time by the method of mechanical vibration assisted induction heating hot-pressing with low pressure and short time.

The present study report two types of ultra-thin shellac fibers that were fabricated using a traditional single fluid electrospinning and a modified coaxial electrospinning. Ethanol was exploited as the solvent of shellac and also a sheath fluid of the coaxial process. A camera was used to observe the electrospinning processes and scanning electron microscope was taken to investigate the prepared shellac nanofibers. A single fluid electrospinning of 64% (w/v) shellac solutions not only clogged the spinneret now and then, but also resulted in fibers with a spindles-on-a-string morphology under a flow rate of 1.0 mL/h and an applied voltage of 12 kV. In sharp contrary, a coaxial electrospinning of 80% (w/v) shellac solutions (under a sheath and core flow rate of 0.2 and 0.8 mL/h, respectively, and an applied voltage of 12 kV) furnished linear nanofibers with an average diameter of 740 ± 60 nm. With the same outflows from the nozzles of spinneret, the ultrathine nanofibers from the modified coaxial process surpassed those from the single fluid process in terms of fibers’ morphology and size. The modified coaxial process described here expands the capability of electrospinning process and opens a new way to obtain thinner nanofibers with fine structural uniformity.

Misfit strain relaxation-induced morphology instability is usually observed in epitaxial heterostructures at high temperatures. In this paper, we report that this morphology instability can occur even at room temperature in epitaxial ZnO/AZO (Al-doped ZnO) core–shell nanowires (NWs). As a result, densely distributed ZnO nanodots (NDs) were self-assembled on the NWs. The growth of NDs was slowed down during aging owing to the gradually reduced misfit strain. The final size and shape of the NDs were highly depended on the shell thickness and the doping ratio. It was proved that the morphology stability could be improved by surface passivation, thinning the shell thickness, or lowering the doping ratio. The results may provide instructive suggestions for the reliable design in strain and surface engineering of nanomaterials.

Fully developed turbulence single phase convection heat transfer of water in pipes filled with sintered porous metal inner rings or solid inner rings was investigated numerically respectively. Numerical calculations were conducted with the Fluent 6.3 code, using the SST k-ω turbulence model. Comparing to solid-ring turbulator pipes, porous-ring turbulator pipes have better comprehensive heat transfer effect. The maximum PEC for porous-ring turbulator pipes is 4.4 and the PEC of solid-ring turbulator pipes is less than 1. It was also analyzed effect of geometric structures on porous-ring turbulator pipe performance. f/f0 for porous-ring turbulator pipes increases with the increasing of Re while Nu/Nu0 decreases with the increasing of Re ,and PEC decreases with the increasing of Re. With the same Re, if the width of the porous ring is equal to the width of groove, f/f0, Nu/Nu0 increases and PEC decreases with the increasing height of porous ring. When the height of porous ring is constant, the f/f0, Nu/Nu0 and PEC decreases with the increasing height of porous ring under the same Re.

This paper reports a theoretical investigation on rapid evaporation of a saline droplet during depressurization. A mathematical model was developed to simulate the droplet temperature variation by considering the ambient pressure change, the heat transfers due to evaporation and convection at the droplet surface, accompanying the heat and mass transfer inside the droplet. The component diffusion and the temperature gradient inside the droplet were mainly discussed by comparing the numerical droplet temperature with the experimental data. The result shows that, the variation of internal concentration is small, while the temperature gradient within the droplet is significant during the evaporation process. In addition, the influencing factors of the droplet temperature variation were analyzed, such as: the final ambient pressure, theinitial salt concentration and the initial droplet temperature. The present model calculations help to understand the thermodynamic process of rapid evaporation of a saline droplet during depressurization.

Research about sea wind load effect on ship loader is completed in this paper. Entity modeling method and solid element is used in the process of finite element modeling. Sea wind is divided into the steady wind and the turbulent wind. The steady wind is disposed as the constant speed wind which can be converted to wind pressure. After the static load solution, modal analysis is conducted which is essential for the following dynamic analysis. Because turbulent wind has random amplitude, direction and frequency, random vibration analysis method is used in the dynamic analysis process. With the results from the three representative positions, it is concluded that the displacement size and dynamic response intensity is in direct proportion to the height of the position.

In order to obtain the concentration, temperature and size variations of a bicomponent moving droplet during evaporation process, a mathematic based on multicomponent droplet evaporation model and droplet motion equation was developed to simulate the evaporation characteristic of a binary decane-ethanol droplet at high temperature nitrogen environment. By numerical calculations, the time evolution of internal concentration distribution within droplet was obtained, and the variations of droplet temperature and dimensionless size were analyzed. The numerical results show that: the droplet temperature variation includes transient heating and equilibrium evaporation at atmospheric pressure; while at high pressure environment, the droplet temperature increases gradually till reaches to ambient temperature. The variations of dimensionless droplet size are deviated from the d2 law due to the concentration variation during evaporation.

In order to achieve high efficiency of new fuel engine, a mathematical model based on mass, momentum and energy equations was developed to describe the motion and evaporation characteristics of a single ethanol droplet in high temperature nitrogen environment. By comparing the numerical results with experimental data, the validity of model was confirmed. The relationships of droplet temperature, velocity, size with time and movement distance under different ambient pressures were analyzed. The calculated results indicate that with a higher ambient pressure, the droplet temperature is higher, the droplet velocity declines faster, the movement distance is shorter; the evaporation rate is slower, and the droplet life is longer. Within the distance where the droplet velocity continuous variation, the droplet temperature rises gradually, the droplet size expands slightly, and with the increase of ambient pressure, the droplet expansion is more significant.

Tungsten oxide is a kind of multifunctional materials with excellent properties for gas sensing, electrochromic and photocatalytic applications. In this study, Tungsten oxide nanoplate thin film was prepared by hydrothermal methods. The as-prepared thin film is composed of tungsten trioxide hydrate nanoplates, which are randomly orientate on the surface. The as-grown nanoplate thin film shows good sensitivity to H2 gas. Dehydration and phase transition to γ-phase tungsten trioxide were found after annealing, and the sensitivity as well as the response time to H2 were improved. We found that the nanoplate in the annealing sample bursts, which raises the surface-to-volume ratio for better hydrogen diffusion and reaction. The sensing mechanism was discussed. The findings provide a way to control the structure and surface morphology for improving the H2 sensing properties of tungsten oxide.

Fluorine-doped TiO2 thin films featuring columnar structure were prepared on fluorine-doped tin oxide (SnO2:F) substrate using a sol–gel method. The F doping ratios were varied in the range of 0–8 %. The effect of [F]/[Ti + F] ratio on the structural, morphological, optical, photocatalytic and low-emissivity properties has been investigated in detail. X-ray diffraction studies revealed that all the composited films are mainly composed of anatase TiO2 and rutile SnO2 without other phases. The prepared TiO2:F films possessed the columnar morphology with the single layer thickness ranging from 28 to 31 nm. The best photocatalytic activity was obtained for the films with 4 % F doping ratio which is mainly attributed to the highest crystallization and crystallite size. The transmission and hemispherical emissivity of the composite films could still reach approximately 70 % and 0.20, which match the requirements of the Chinese National Standard (GB/T18915.2-2002), promoting the films for the practical applications.

Degrading Mg and its alloys are a category of implant materials for bone surgery, but rapid corrosion in physiological environment limits their clinical applications. To improve the corrosion resistance of Mg-based implants, a biodegradable composite polymer coating is deposited on an Mg rod in this work. The strategy is to decorate Mg surfaces with poly(γ-glutamic acid)-g-7-amino-4-methylcoumarin/hydroxyapatite (γ-PGA-g-AMC/HAp) composite nanoparticles through electrophoretic deposition in ethanol. The morphology and chemical composition of the resulting coating material are determined by scanning electron microscopy and Fourier transform infrared spectroscopy. Sample rods of bare Mg and coated Mg are implanted intramedullary into the femora of New Zealand white rabbits, periodic radiography and post-autopsy histopathology of each sample are analyzed. The obtained in vivo results clearly confirm that the coating material decreases degradation rate of the underlying Mg sample and appears good histocompatibility and osteoinductivity. The main aim of this work is to investigate the degradation process of bare Mg and coated Mg samples in bone environment and their effect on the surrounding bone tissue.

Magnesium (Mg) has recently received increasing attention due to its unique biological performance, including cytocompatibility, antibacterial and biodegradable properties. However, rapid corrosion in physiological environment and potential toxicity limits its clinical applications. To improve the corrosion resistance meanwhile not compromise other excellent performance, self-assembled colloidal particles were deposited onto magnesium surfaces in ethanol by a simple and effective electrophoretic deposition (EPD) method. The fabricated functional nanostructured coatings were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses, and scanning electron microscopy (SEM). The electrochemical test, pH value, and Mg ion concentration data show that the corrosion resistance of Mg samples is enhanced appreciably after surface treatment. In vitro cellular response and antibacterial capability of the modified Mg substrates are performed. Significantly increased cell adhesion and viability are observed from the coated Mg samples, and the amounts of adherent bacteria on the treated Mg surfaces diminish remarkably compared to the bare Mg. Furthermore, the bare and coated Mg samples were implanted in New Zealand white rabbits for 12 weeks to examine the in vivo long-term corrosion performance and in situ inflammation behavior. The experiment results confirmed that compared with bare Mg substrate the corrosion and foreign-body reactions of the coated Mg samples were suppressed. The above results suggested that our coatings, which effectively enhance the biocompatibility, antimicrobial properties, and corrosion resistance of Mg substrate, provide a simple and practical strategy to expedite clinical acceptance of biodegradableMg and its alloys. Statement of Significance Biomedical Mg metals have been considered as promising biodegradable implants because of their intended functions, such as cytocompatibility, antibacterial, and biodegradable properties. However, rapid corrosion in physiological environment limits their clinical applications. Alloying and surface coatings have been used to reduce the degradation rate. But this would compromise other excellent performance of Mg samples, including antibacterial and anti-inflammatory activity. Thus, while the rapid degradation of Mg samples must be solved, good antibacterial property and acceptable cytocompatibility are also necessary. In this study, polymer-based coatings were fabricated on Mg surfaces by electrophoretic deposition of poly(isobornyl acrylate-co-dimethylaminoethyl methacrylate)/tannic acid (P(ISA-co-DMA)/TA) colloidal particles. It suggested that the coating materials effectively improved the biocompatibility, antimicrobial behavior, and corrosion resistance of biomedical Mg.

Copper tube was the air conditioner heat dissipation commonly used material, their hydrophilic and corrosion resistance was great significance to improve the air conditioner heat dissipation effect and the service life. Hydrophilic film was prepared with key components of silica sol and acrylic. The experiment process mainly investigated the effect of soaking time, temperature, pH value, silica sol concentration and the acrylate concentration on the hydrophilic film. Hydrophilic property and corrosion resistance were tested. The best technological conditions were as follows: at room temperature, 5min, the silica sol concentration of 60%, the acrylate concentration of 1%, pH = 13. The experimental results show that hydrophilic angle was 13°, and corrosion resistance as good as the deactivation film.

An efficient continuous wave (CW) THz source working at nominal room temperature is described. Optically pumped room temperature THz emission is observed from various kinds of semiconductor bulk crystals. In order to investigate the emission mechanism, temperature dependences of terahertz emission intensity in various semiconductors are measured. Semiconductor samples used are InSb, InSb:Ge, InAs, GaSb, Ge, and Si. From these results, it is shown that the temperature dependences of emission characteristics are different between direct and indirect transition semiconductors, and that the high resistive Ge is suitable for room temperature THz emitter via intracenter transitions excited by IR pump lasers.

Diatomite/polyacrylic acid composite was synthesized by using inverse suspending polymerization method under different diatomite content, dispersant content and neutralization degree with orthogonal experiments. The surface morphology, structure and humidity controlling properties of composite were observed and determined. The results show that diatomite/polyacrylic acid composite is in a block like structure with different size. During the polymerization process, acrylate monomer is grafted with hydroxyl on the surface of diatomite and then inserted successfully into the void of diatomite. The impact of three factors on the humidity controlling behavior of composites increases by the order of dispersant content, neutralization degree and diatomite content. The optimum preparation parameters are diatomite content of 40%, dispersant content of 15%, neutralization degree of 90%.

Microfluidic is of great significance for biomedical research and chemical engineering. The mixing of liquids is an essential and necessary procedure for the sample preparation. Due to the low Reynolds number, laminar flow is dominant in a microfluidic channel and it is difficult to mix the fluids in the microchannel quickly and effectively. To improve the mixing efficiency of the liquids in microfluidic channels, we develop an acoustic mixer based on single microbubble oscillation. By designing the cylinder structure on the bottom surface, when the fluid flows through cylinder structure with a diameter of 40 m, the microbubble can be generated by the surface tension of the liquid. The device is fabricated by using standard soft lithography and the replica moulding technique, ensuring the stability and repeatability of the mixing. A piezoelectric transducer (PZT) with a resonant frequency of 165 kHz is attached to the polydimethylsiloxane microfluidic device on the glass substrate by ultrasound coupling gel. When the microbubble is excited by the PZT at a resonant frequency of 165 kHz, microbubble oscillates immediately. To verify whether ultrasound can induce microbubble cavitation, a passive cavitation detection system is established. The results show that the higher harmonics can be detected, indicating that the stable cavitation occurs. The microstreaming induced by the oscillating microbubble disturbs the fluid dramatically, achieving the mixture of liquids. Particle image velocimetry method is utilized to characterize the microstreaming, and a pair of counter-rotating vortices in the microchannel is detected. Furthermore, to test the performance of the device, the deionized water and rhodamine B are injected into the Y-shape microchannel. Relative mixing index is used to quantitatively analyze the mixing performance by measuring the grayscale values of the optical images. The results indicate that with the increase of the input power, mixing time can be shortened correspondingly. When the input power is 14.76 W, the mixing process is ultrafast, within 37.5 ms the high mixing uniformity can be achieved to be 92.7%. With the advantages of simple design, high efficient and ultrafast mixing, and low power consumption, this oscillating microbubble-based acoustic micromixer may provide a powerful tool for various biochemical studies and applications.

PurposeIn order to manufacture scaffolds for tissue engineering, a dynamic mask rapid prototyping system to cure UV‐curable biodegradable material was developed. The aim of this paper is to document this system.Design/methodology/approachA digital micro‐mirror device (DMD) was used as the dynamic mask generator, with each layer's mask pattern dictated by our self‐developed software. To build the scaffolds, UV light reflected by the DMD was then focused onto the biodegradable material to cure it. The biodegradable material used in this experiment was a mixture of 85/15 PLGA, PEG‐HEMA, and a photo‐initiator.FindingsThe dynamic mask rapid prototyping system was successfully built and scaffolds made of UV‐curable biodegradable material were fabricated to verify the system capacity. The working exposure time for each layer was 45 s except for the first layer, which was 60 s. Scaffolds with 0°/90° and 60°/120° strips in alternating layers were fabricated and the pore size error in X and Y axes of 0°/90° design was found to be 7.33 and 2.13 percent, respectively. Preliminary cell culture tests indicate the fabricated scaffold is not harmful to MG‐63 cell growth.Research limitations/implicationsDifferent scaffold designs and more UV‐curable biodegradable materials may be further implemented and tested through this system.Originality/valueThis research developed a novel system for tissue engineering scaffold fabrication which can process UV‐curable biodegradable material.

In this paper, experiments are conducted to reveal the effects of polishing parameters such as rotational speed, applied pressure, locations of nozzles for slurry, and flow rate of flurry on surface characteristics when polishing an aluminum based rigid disk. A double-sided polishing machine is used in these experiments and an inner pin ring is held still during the process, so that the removal rates of disks at different locations are different. It was shown that the removal rate for outer disks is less than that for inner disks. This phenomenon is in contrast to that predicted using the popular Preston equation. Although it was shown that the removal rate increases as the relative velocity or the applied pressure increases, it is not proportional to either the applied pressure or the relative speed as described by the Preston equation.

Size-dependent exciton spin relaxation dynamics in CdTe colloidal quantum dots is studied at room temperature with the cross-polarized heterodyne third-order nonlinear transient grating technique The CdTe exciton spin relaxation reveals a mono-exponential decay behavior with a time constant of 0.1-0.5 ps when the pump-probe photon energy is tuned to be in resonance with the lowest exciton absorption transition (1Se-1Sh). The exciton spin relaxation in quantum dot is mainly governed by the hole spin flip process and ascribed to the transitions between bright-dark exciton fine structure states, i.e. J= 1+2. This finding suggests that the exciton spin relaxation rate in CdTe quantum dot is inversely proportional to the fourth power of quantum dot size.

The pore microstructures in two viscouse rayon-based ACF samples were characterized by nitrogen adsorption and HRTEM. For TEM, a two-dimensional fast Fourier transform (FFT) of the original TEM images was performed, and pores in different size ranges were extracted by the inverse FFT (IFFT) operation. The surface fractal dimensions of the samples were evaluated by using both N(2) adsorption and TEM image analysis. The results show that TEM can portray the shapes of the pore, and it can give a quantitative evaluation of surface irregularity that is consistent with nitrogen adsorption results.

Thermal instability of power SiGe heterojunction bipolar transistor (HBT) at high current over a wide temperature range restricts the applications of the device in RF and microwave circuits. In order to improve the thermal instability, the influences of Ge profile in a base region on the electrical and thermal characteristics of microwave power SiGe HBT are studied with the aid of the model of multi-finger power SiGe HBT established by SILVACO TCAD. It is shown that for the HBT with graded step Ge profile, a higher cut-off frequency fT can be achieved due to the accelerating electric field caused by the graded step Ge concentration in the base region when compared with the device with uniform Ge profile. The influences of temperature on current gain β and fT are weakened, which avoids the drift of electrical characteristics over a wide temperature range. Although the temperature of device is lowered, the temperature of each emitter finger is still non-uniform. Considering the difference in heat dissipation among emitter fingers, a new device with non-uniform emitter finger spacing in layout and a graded step Ge profile in base region is designed. For the new device, the uniformity of temperature among emitter fingers is achieved, higher fT is kept, β and fT are less sensitive to temperature variation. Hence the thermal instability is obviously improved compared with the device with uniform emitter finger spacing and uniform Ge profile in base region, indicating the superiority of the new device at high current over a wide temperature range.

Ta-doped ZnO transparent conductive films are deposited on glass substrates by rf sputtering at 300 °C. The influence of the post-annealing temperature on the structural, morphologic, electrical, and optical properties of the films is investigated by x-ray diffraction, Hall measurement, and optical transmission spectroscopy. The lowest resistivity of 3.5 × 10−4 Ω.cm is obtained from the film annealed at 400 °C in N2. The average optical transmittance of the films is over 90%. The optical bandgap is found to decrease with the increase of the annealing temperature.