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A novel Tm3+/Tb3+/Sm3+ tri-doped Na5Y9F32 single crystal was synthesized by a modified Bridgman method for the propose of white light emitting diodes. The fluorescence spectra of various Sm3+ ion concentrations and fixed 0.4 mol% Tm3+ and 0.5 mol% Tb3+ were measured and studied systematically excited by near-ultraviolet light of 355 nm. The Sm3+ ion concentration takes apparent effect on the relative intensity of peaks in the visible region and the color coordinate combining from these emission bands. A near pure white light emission with color coordinates (0.3295, 0.3057) and color temperature (5657 K) can be obtained when the concentrations of Tm3+, Tb3+ and Sm3+ ions are 0.4 mol%, 0.5 mol% and 0.8 mol%, respectively. Furthermore, the practical down-conversion internal quantum yield was measured by integrating spheres at about 14.39%. The tri-doped Na5Y9F32 single crystal shows a high thermal stability inferring from the temperature dependent emission in which the integrated emission intensities are reduced only by ∼3% with the increase of temperature from 280 to 450 K. The present results demonstrate that the Tm3+/Tb3+/Sm3+ tri-doped Na5Y9F32 single crystal may provide a promising candidate for white light-emitting diodes, luminescent materials and fluorescent display devices.

Crack velocity, gas ejection, and stress waves play an important role in determining delay time, designing a blast and understanding the mechanism of rock fragmentation by blasting. In this paper, the emerging times of the earliest cracks and gas ejection on the lateral surfaces of cylindrical granite specimens with a diameter of 240 mm and a length of 300 mm were determined by high-speed photography, and the strain waves measured by an instrument of dynamic strain measurement during model blasting. The results showed that: (1) the measured velocity of gas penetration into the radial cracks was in a range of 196–279 m/s; (2) the measured velocity of a radial crack extending from the blasthole to the specimen surface varied from 489 to 652 m/s; (3) the length of strain waves measured was about 2800 µs, which is approximately 1000 times greater than the detonation time. At about 2850 µs after detonation was initiated, gases were still ejected from the surface cracks, and the specimens still stood at their initial places, although surface cracks had opened widely.

Conductive hydrogel-based wearable strain sensors with tough, stretchable, self-recoverable, and highly sensitive properties are highly demanded for applications in electronic skin and human-machine interface. However, currently, hydrogel-based strain sensors put forward higher requirements on their biocompatibility, mechanical strength, and sensitivity. Herein, we report a poly(vinyl alcohol)/phytic acid/amino-polyhedral oligomeric silsesquioxane (PVA/PA/NH2-POSS) conductive composite hydrogel prepared via a facile freeze-thaw cycle method. Within this hydrogel, PA acts as a cross-linking agent and ionizes hydrogen ions to endow the material with ionic conductivity, while NH2-POSS acts as a second cross-linking agent by increasing the cross-linking density of the three-dimensional network structure. The effect of the content of NH2-POSS is investigated, and the composite hydrogel with 2 wt % NH2-POSS displays a uniform and dense three-dimensional (3D) network microporous structure, high conductivity of 2.41 S/m, and tensile strength and elongation at break of 361 kPa and 363%, respectively. This hydrogel is biocompatible and has demonstrated the application as a strain sensor monitoring different human movements. The assembled sensor is stretchable, self-recoverable, and highly sensitive with fast response time (220 ms) and excellent sensitivity (GF = 3.44).

All-inorganic cesium lead triiodide (CsPbI3) perovskite has been widely researched due to its outstanding photovoltaic properties. At room temperature, there are two orthorhombic CsPbI3 phases (black γ-CsPbI3 perovskite and yellow δ-CsPbI3 non-perovskite). In this study, these two polymorphic structures have been studied via density functional theory calculations in respect to their electronic and elastic properties. Our calculation results give full mapping of Young's moduli of the γ-CsPbI3 structure for all crystallographic orientations, which reveal that the optimum directions for stabilizing the γ-CsPbI3via strain are approximately along 〈012〉. Moreover, we found that these two polymorphs have distinct stiffness along respective octahedral chains due to their different kinds of octahedral connections. Furthermore, the calculated band structures and density of states disclose that both phases have direct bandgaps, and the bandgap of δ-CsPbI3 is much wider due to its weak Pb 6p-I 5p antibonding coupling in the conduction band and low octahedral connectivity. Our findings provide fundamental elastic and electronic insights which are instructive for strain engineering of photovoltaic γ-CsPbI3.

The Fourier-based gradient field integration method can efficiently reconstruct transparent surfaces from the measured gradient data in the Shape-from-polarization method. However, for the differentiation operator having large truncation errors and lacking constraints on adjacent heights, it will increase the reconstructing error of the Fourier-based integration method. This paper presents an accurate Fourier-based integration approach to improve the reconstruction accuracy, in which a new differentiation operator is derived by limiting the truncation error and increasing heights and slopes in the operator. In order to modify the data obtained by the new operator to meet the requirements of both periodicity and size for the use of the discrete Fourier transform, we propose a method to extend the raw gradient data by first performing antisymmetric extension and then performing periodic extension. A series of simulations and experiments have been developed to verify the performance of the proposed method. By comparing the approach of this paper with other Fourier-based approaches, including Frankot-Chellappa, Southwell-FT and Simpson-FT, both of the simulation and experiment results show that the proposed Fourier-based integration method performs a higher accuracy than other approaches. In the reconstruction experiment, the reconstruction error can be reduced from 0.065 ~ 0.081 mm to 0.020 mm for the spherical surface, and from 0.060 ~ 0.12 mm to 0.016 mm for the free-form surface.

The development of subsea injection water disinfection systems will enable the novel exploration of offshore oilfields. Ultraviolet light emitting diodes (UV-LEDs) with peak wavelengths at 255 nm, 280 nm, 350 nm, and combinations of 255 nm and 350 nm, and 280 nm and 350 nm were investigated in this study to determine their efficiency at disinfecting saprophytic bacteria, iron bacteria, and sulfate reducing bacteria. Results show that UV-LEDs with peak wavelengths at 280 nm were the most practical in this domain because of their high performance in both energy-efficiency and reactivation suppression, although 255 nm UV-LEDs achieved an optimal germicidal effect in dose-based experiments. The use of combined 280 nm and 350 nm wavelengths also induced synergistic bactericidal effects on saprophytic bacteria.

The magnesium alloys Mg-0.5Mn-2Zn, Mg-1.0Mn-2Zn, and Mg-1.5Mn-2Zn (wt.%) with potential biomedical applications, synthesized by powder metallurgy, were investigated to evaluate the influence of manganese content on their microstructure, mechanical properties, and corrosion resistance. The results show that Mg-Mn-Zn alloys prepared by powder metallurgy reached the maximum compressive stress of 316 MPa and the maximum bending strength of 186 MPa, showing their good resistance to compression and bending, and meeting the mechanical properties required for the human bone plate. With an increase in manganese content, the corrosion resistance improved. In the polarization curve, the maximum positive shift of corrosion potential was 92 mV and the maximum decrease of corrosion current density was 10.2%. It was concluded that, of the alloys tested, Mg-1.0Mn-2.0Zn (wt.%) had the best overall performance, and its maximum compressive stress force and corrosion current density reached 232.42 MPa and 1.32 × 10−5 A·cm−2, respectively, being more suitable for service in human body fluids.

The China fusion engineering test reactor (CFETR) vacuum vessel is welded by narrow gap TIG (NG-TIG) welding, and the welding residual stress of the CFETR vacuum vessel can be redistributed by trailing welding ultrasonic impact treatment. In order to investigate the feasibility of the residual stress removing scheme, and to obtain the optimal trailing ultrasonic impact treatment technological parameters in the process of removing welding residual stress, a welding model that similar to vacuum vessel welding seam is established by using ABAQUS software, a NG-TIG welding heat source subroutine which is written in FORTRAN language used to simulate NG-TIG welding. According to the welding simulation results, a trailing welding ultrasonic impact treatment model is established, and the effects of the impact pin number, the impact method, the impact pin diameter and the impact frequency on welding residual stress are studied. The results show that the longitudinal residual stress in welding seam and its adjacent area and the lateral residual stress in the whole region have been obviously decreased by different trailing welding ultrasonic impact processes, and have made the tensile stress in the welding seam and its adjacent area has been changed into compressive stress, which can provide theoretical guidance and reference for actual production.

Nine blasts with cylindrical granite specimens were carried out under different stemming conditions. All rock specimens had a diameter of 240 mm and a length of 300 mm. Explosive Pentaerythritol tetranitrate (PETN) with specific charges 0.2 and 0.3 kg/m 3 were used, and the blasts were carried out in a large explosion chamber. Each rock specimen was enclosed by a steel box in the chamber during blasting, without constraint or confinement to the specimen from lateral and top sides. During blasting a high-speed camera was used to film the blasting process and monitor the gas ejection. After each blast all fragments were collected, sieved and analyzed. The experimental results showed that: (1) the blasts with full sand stemming yielded better (finer) fragmentation than the blasts with partial steel stemming at a constant specific charge, and (2) gas ejection from the collars of blastholes occurred much earlier in the blasts with partial steel stemming than in the blasts with full sand stemming. Based on the experimental results, it can be concluded that it is extremely important to prevent gas ejection from the collars in order to achieve desirable rock fragmentation.

The hot-dip galvanized coating was produced on the 7075 aluminum alloy plate by immersion in a pure zinc bath at different temperature from 440°C to 470°C for different modification time (between 1 min and 10 min). The hot-dip galvanized of the treated and un-treated samples were investigated by using scanning electron microscopy (SEM) with EDX analysis, X-ray diffraction (XRD), hardness measurements and potentiodynamic polarization curves. There were three layers fabricated on the 7075 substrate surface, specifically, zinc-rich layer, two-phase mixed layer Al-Zn and interdiffusion layer. Moreover, the 7075 aluminum alloy with the hot-dip galvanized coating exhibit higher hardness and better anti-corrosion properties in comparison with the 7075 substrate.

Cryogels are a subset of hydrogels synthesized under sub-zero temperatures: initially solvents undergo active freezing, which causes crystal formation, which is then followed by active melting to create interconnected supermacropores. Cryogels possess several attributes suited for their use as bioscaffolds, including physical resilience, bio-adaptability, and a macroporous architecture. Furthermore, their structure facilitates cellular migration, tissue-ingrowth, and diffusion of solutes, including nano- and micro-particle trafficking, into its supermacropores. Currently, subsets of cryogels made from both natural biopolymers such as gelatin, collagen, laminin, chitosan, silk fibroin, and agarose and/or synthetic biopolymers such as hydroxyethyl methacrylate, poly-vinyl alcohol, and poly(ethylene glycol) have been employed as 3D bioscaffolds. These cryogels have been used for different applications such as cartilage, bone, muscle, nerve, cardiovascular, and lung regeneration. Cryogels have also been used in wound healing, stem cell therapy, and diabetes cellular therapy. In this review, we summarize the synthesis protocol and properties of cryogels, evaluation techniques as well as current in vitro and in vivo cryogel applications. A discussion of the potential benefit of cryogels for future research and their application are also presented.

Aluminum alloy is widely used in automobile, aerospace and other fields due to its excellent strength-to-weight ratio. And machined surface integrity is an important factor affecting the service performance of parts. In this paper, surface integrity of turned 6061 aluminum under liquid nitrogen cooling condition was studied. The results shows that, cryogenic cooling cutting with liquid nitrogen could effectively reduce the surface roughness, inhibit the generation of residual tensile stress and improved the surface microhardness compared with dry and emulsion cooling cutting. Cryogenic cooling processing has great advantages in cutting machining.

Compared to conventional metallic materials, biodegradable material magnesium and calcium (Mg-Ca) alloys are attractive to be new participants as implants. It can avoid stress shielding and provide sufficient mechanical strength as the similar mechanical properties to human bone. In this study, Mg-0.8wt%Ca and Mg-1.6wt%Ca are prepared and Mg-0.8wt%Ca is dry milled. Overall carbide tool is used in the process and the roughness generated by different combination of cutting parameters, i.e. cutting speed, feed, and depth of cut are studied.

Biomedical materials are materials that can be implanted in an organism or combined with biological tissue. They are used for the diagnosis, treatment, and replacement of tissues or organs, and enhance their functions. With high strength, good toughness and bending fatigue strength, excellent processing performance which can not be replaced by other medical materials, biological medical metallic materials, such as stainless steel, cobalt based alloy, titanium and titanium alloys and noble metal are widely used in medical field. The surface topography has a great influence on the function of the parts, especially for the wear, vibration, noise, corrosion resistance of the friction surface. And the surface morphology of medical metal is very important in the influence of its corrosion resistance.

High efficiency and high speed are the development directions of modern manufacturing technologies. In the last two decades, high speed machining is successfully applied in cutting steel and alumina alloy, due to its unique advantages. However, it is not yet prevalent in powder metallurgy (PM) superalloy machining. This work focuses on the shear angles and influencing rules in high speed machining PM nickel based superalloy, in order to provide reliable theoretical and practical methods in high efficiency/speed machining this kind of material in production practice.

The Na5Y9F32 fluoride single crystals tri-doped with ∼1 mol% Ho3+/∼1 mol% Er3+, and various concentrations of Pr3+ (0, 0.5, 0.8 and 1.0 mol%) were successfully grown by a modified Bridgman method. The absorption, Raman, emission spectra and fluorescence decay curves of Pr3+/Ho3+/Er3+ tri-doped Na5Y9F32 single crystals were studied systematically. The intensity parameters (Ω2 = 1.96 × 10−20 cm2, Ω4 = 1.66 × 10−20 cm2, Ω6 = 1.46 × 10−20 cm2) of Er3+ ions and emission cross-sections at ∼2.7 μm (1.76×10−20 cm2) and ∼2.9 μm (1.34×10−20 cm2) were calculated according to the measured absorption spectra. The emission intensities at ∼2.7 μm of Er3+: 4I11/2 → 4I13/2 and ∼2.9 μm of Ho3+: 5I6→5I7 were enhanced gradually as increase of Pr3+ concentrations from 0 to 1.0 mol% under excitation of 800 nm laser diode (LD). However, the ∼2.0 μm of Ho3+: 5I7→5I8 and ∼1.5 μm of Er3+: 4I13/2 → 4I15/2 were gradually reduced. The introduction of Pr3+ can greatly reduce the lifetimes of Er3+: 4I13/2 and Ho3+: 5I7. The energy transfer from Er3+: 4I13/2 to Ho3+: 5I7 level and depopulating Er3+: 4I13/2 and Ho3+: 5I7 levels under the action of Pr3+ ions are responsible for the enhancement of ∼2.7 and ∼2.9 μm emissions. The Pr3+/Ho3+/Er3+ tri-doped Na5Y9F32 single crystal may become a new choice for ∼3.0 μm mid-infrared solid-state laser.

The Keggin-type polyoxometalates (POMs) are effective catalysts for oxidative desulfurization (ODS) and confining these POMs in metal-organic frameworks (MOFs) is a promising strategy to improve their performances. Herein, postsynthetic modification of POMs confined in MOFs by adding thiourea creates more unsaturated metal sites as defects, promoting ODS catalytic activity. Additional modification by confining 1-butyl-3-methyl imidazolium POMs in MOFs is performed to obtain higher ODS activity, owing to the affinity between electron-rich thiophene-based compounds and electrophilic imidazolium compounds. The ODS catalytic activities of four Zr-MOF-based composites (bottle around ship) including phosphomolybdate acid (PMA)/UiO-66, [Bmim]3 PMo12 O40 /UiO-66, PMA/Thiourea/UiO-66, and [Bmim]3 PMo12 O40 /Thiourea/UiO-66 are therefore investigated in detail. In order to explore the catalytic mechanism of these MOF composites, their microstructures and electronic structures are probed by various techniques such as X-ray diffraction, thermogravimetric analysis, Fourier transform infrared, Raman, scanning electron microscope, transmission electron microscope, BET, X-ray photoelectron spectroscopy, EPR, UV-vis, NMR spectra, and H2 -temperature-programmed reduction. The results reveal that phosphomolybdate blues and imidazolium phosphomolybdate blues with different Mo5+ /Mo6+ ratios with the Keggin structure are confined in defected UiO-66 for all four composites. This approach can be applied to design and synthesize other POMs/MOFs composites as efficient catalysts.

A novel Na5Y9F32 single crystals tri-doped with fixed ~0.8 mol% Ho3+, ~1 mol% Yb3+ and various Pr3+ from 0 to 0.8 mol% were successfully grown by a modified Bridgman method for 2.9 μm mid-infrared application. The effects of Pr3+ ion on the 2.9 μm emission was investigated systematically with the help of the absorption spectra, emission spectra and fluorescence decay curves. The emission intensity at ~2.9 μm of Ho3+: 5I6 → 5I7 was enhanced gradually as increase of Pr3+ concentration from 0 to 0.8 mol% under excitation of 980 nm laser diode (LD). The maximum emission cross-section at ~2.9 μm was calculated to be 5.62 × 10−20 cm2 according to the measured emission spectra. The energy transfer mechanism among Ho3+, Yb3+ and Pr3+ was studied. When the Pr3+ ion concentration reached 0.8 mol%, the energy conversion efficiencies for Ho3+: 5I7 → Pr3+: 3F2 and Ho3+: 5I6 → Pr3+: 3F4 were estimated about ~51.76% and ~15.73%, respectively. A remarkably augmented conversion process of Ho3+: 5I7 → Pr3+: 3F2 by the introduction of Pr3+ ion into Ho3+/Yb3+ system results into the enhancement of ~2.9 μm emission. The Pr3+ ion takes as an effective deactivation of the Ho3+ ion in the Na5Y9F32 single crystal. The Pr3+/Ho3+/Yb3+ tri-doped Na5Y9F32 single crystals may become a new choice for ~2.9 μm mid-infrared solid-state laser due to its both excellent optical properties and chemical stability.

The mid-wave and long-wave dual-band infrared scene projector (IRSP) is a practical instrument to test various infrared imaging systems in the experiment of hard-ware-in-the-loop (HWIL) simulation. It comprises two illumination modules and a telecentric projection module with dual field of view, covering atmospheric bands from 3.7 μm to 4.8 μm and 8 μm to 12 μm. In order to prevent the influence of temperature changes on the quality of projected images, the appropriate operating temperature range should be predicted during the development and design stages. In this paper, the integrated design of optical components is proposed, focusing on improving the temperature adaptability. Taking into account the different thermal environments faced by the illumination and the projection modules, opto-thermal analyses are carried out using finite element analysis (FEA) models respectively. According to the conditions of heat transfer, temperature field and the corresponding displacement field are calculated based on the quasi-static-processing approach. The least squares algorithm is adopted to fit the thermally induced deformation data for determining the Zernike polynomials of each lens’s surface. And the optical performance of the IRSP is evaluated with the help of a ray-tracing software. The numerical simulations and the laboratory testing results show that the IRSP has good temperature adaptability in the temperature range from 10 °C to 35 °C.

This paper presents the results of axial compression tests of steel-reinforced concrete-filled square steel tubular (SRCFSST) stub columns after exposure to elevated temperature. A total of 135 SRCFSST specimens are designed and tested, including 27 specimens that are unheated and 108 that are heated for different times. Each test examines the effects of concrete strength, width-to-thickness ratio of the square steel tube, section steel ratio and heating times on the strength, deformation and ductility characteristics of the specimen. Test results indicate that the section steel ratio has the greatest effect on the post-yield behavior of the SRCFSST stub columns. On the other hand, temperature has the greatest effect on the residual bearing capacity of the SRCFSST stub columns. The section steel ratio has the second greatest effect on the residual bearing capacity, followed by the concrete strength grade and the width-thickness ratio of the steel tube. Equations are proposed to predict the ultimate strength of the composite columns at room temperature and after exposure to elevated temperature. The computed values from the formulae are consistent with the experimental results.

A diode end-pumped Tm:LuAG laser at room temperature was reported. The thermal lens effect of Tm:LuAG crystal was analyzed, the distribution of the light field and thermal field in the crystal was simulated moreover. In this paper, by using plane-concave resonator, the continuous 2 μm laser output with maximum output power of 10.8 W is obtained. The slope efficiency is 19.56% and the optical-to-optical conversion efficiency is 25.71%. The beam quality factors M2 are 1.24 and 1.28 in the x and y directions respectively.

In this paper, the Na5Y9F32 single crystals tri-doped with ~3 mol% Yb3+/~1 mol% Ho3+, and different concentrations of Ce3+ (0, 0.2, 0.25, 0.35 and 0.4 mol%) were successfully grown by the modified Bridgman method. The absorption spectra, fluorescence spectra and decay curves of co-doped Yb3+/Ho3+ Na5Y9F32 single crystals with different concentrations of Ce3+ ions were measured. The intensity parameters of Ho3+ ions were calculated according to Judd–Ofelt theory and measured absorption spectra. The emission spectra showed the up-conversion (UC) emission intensity at 545, 657, and 755 nm reduced significantly as the addition of Ce3+. When the concentration of Ce3+ reached about 0.25 mol%, the maximum fluorescence intensity of ~2.0 μm was obtained, and the emission cross section reached 2.29 × 10−20 cm2. The mechanism of up-conversion reduction and ~2.0 μm emission enhancement in Ce3+/Yb3+/Ho3+ tri-doped Na5Y9F32 crystals was discussed from their energy level diagrams and optical spectra. The cross-relaxation (CR) energy transfer efficiency between Ho3+ and Ce3+ ions were 36.3% calculated from the measured lifetime of Yb3+ /Ho3+ co-doped and Ce3+/Yb3+/Ho3+ tri-doped samples. Analysis on the fluorescence dynamics indicated that electric dipole-dipole is dominant for the energy transfer from Ho3+ to Ce3+ ions. The results show that Ce3+/Yb3+/Ho3+ tri-doped Na5Y9F32 crystals has certain application prospects in improving the performance of Ho3+ ~2.0 μm solid-state laser.

Radiopaque resorbable inferior vena cava filter (IVCF) were developed to offer a less expensive alternative to assessing filter integrity in preventing pulmonary embolism for the recommended prophylactic period and then simply vanishes without intervention. In this study, we determined the efficacy of gold nanoparticle (AuNP)-infused poly-p-dioxanone (PPDO) as an IVCF in a swine model. Infusion into PPDO loaded 1.14±0.08 % AuNP by weight as determined by elemental analysis. The infusion did not alter PPDO’s mechanical strength nor crystallinity (Kruskal−Wallis one-way ANOVA, p

Irreversible electroporation (IRE) is a novel non-thermal ablative treatment for cancer patients with unresectable tumor. IRE kills tumor cells by applying a strong electric field across the cell membrane, thereby creating irreparable pores. Compared to conventional thermal ablation, IRE is effective in perivascular tissues and can preserve the surrounding sensitive structures. However, tumor cells may survive in the regions exposed to insufficient electric field strength, and cause tumor relapse afterwards. We prepared a doxorubicin-loaded polymeric micelles system (M-Dox) using oil-in-water emulsion. The resultant M-Dox was 37.9 ± 3.2 nm in size with a Dox loading of 4.3% by weight. M-Dox is toxic to multiple human cancer cell lines with IC50 values in nanomolar and micromolar range. When combined with IRE in a hepatic carcinoma mouse xenograft model, the tumor treated with the combination therapy (IRE + M-Dox) was the highest in both M-Dox uptake and percentage of necrosis. Immunohistochemical staining also confirmed that the fewest proliferating cells were present after the combination therapy. Our data suggested that M-Dox was an effective adjuvant treatment to enhance the anti-tumor efficacy of IRE.

The interpenetrating double metal phase composite is anisotropic. According to the structural and mechanical properties, the cutting process becomes more complicated. In this work, experimental investigation was systematically studied by means of turning experiments, and focused on cutting force and surface roughness; extra attention has been paid to the cutting phenomena in the zone of reinforcing phase and bimetal interface. Cutting force performance is similar to the ordinary materials, but there are several impact forces in cutting process. In addition, it is easy to produce cracks and exfoliations at metal/metal interface. These phenomena will lead to the decline of the machined surface quality.

A novel large-scale fabrication technology for single-walled boron nitride nanotube (BNNT) relying on a template of single-walled carbon nanotube (SWCNTs) was introduced. In order to obtain large-scale product, the high-energy ball milling-aided heating technology was used to promote the formation of BNNTs. And arc-discharge methods were used to provide nitrogen ion source. The products were oxidized at 800 °C in air atmosphere to obtain pure BNNTs. The structure and morphology of BNNTs were characterized by X-ray diffraction, transmission electron microscopy, Fourier transformation infrared spectroscopy, and thermogravimetric analysis. The multitudinous industrialized preparation methods for BNNTs were realized as a simple and effective route.

Here, the fabrication of unimolecular micelles functionalized with helical polymeric chains as a chiral nucleating agent in enantioselective crystallization is reported. Starting from a fractionated hyperbranched polyester (Boltorn H30), the ring-opening polymerization of l-lactic acid (LLA) and subsequent terminal-group modification affords the alkyne-Pd(II)-anchored hyperbranched macroinitiator (H30-PLLA-Pd). By taking advantage of a Pd(II)-catalyzed living polymerization of chiral pendant modified l- or d-phenyl isocyanide (PI) monomers, well-defined chiral unimolecular micelles (H30-PLLA-PPI) grafted with radiating helical PPI coronas of one predominant screw sense are obtained. The resultant chiral materials demonstrate excellent application in the enantioselective crystallization of racemic threonine in water, and a 92% enantiomeric excess value of the residual solution is obtained. It is believed this present proof of concept and methodology are facile and powerful for preparing novel and versatile chiral materials with different topological structures, not only applicable to PPI but also to other types of polymers.

Failure to remove a retrievable inferior vena cava (IVC) filter can cause severe complications with high treatment costs. Polydioxanone (PPDO) has been shown to be a good candidate material for resorbable IVC filters. However, PPDO is radioluscent under conventional imaging modalities. Thus, the positioning and integrity of these PPDO filters cannot be monitored by computed tomography (CT) or x-ray. Here we report the development of radiopaque PPDO IVC filters based on gold nanoparticles (AuNPs). Commercially available PPDO sutures were infused with AuNPs. Scanning electron microscopy analysis confirmed the presence of AuNP on the surface of PPDO. Micro-CT and x-ray images of the AuNP-infused PPDO sutures showed significant signal enhancement compared to untreated PPDO sutures. Elemental analysis showed that gold loading exceeded 2000 ppm. Tensile strength and in vitro cytotoxicity showed no significant difference between AuNP-infused and untreated PPDO. In a 10-week stability study, neither the gold content nor the radiopacity of the infused PPDO sutures significantly changed in the first 6 weeks. The increased attenuation of AuNP-infused PPDO sutures indicates their major advantage as a radiopaque resorbable filter material, as the radiopacity allows monitoring of the position and integrity of the filter, thereby increasing its safety and efficacy.

Cutting tool geometry should be very much considered in micro-cutting because it has a significant effect on the topography and accuracy of the machined surface, particularly considering the uncut chip thickness is comparable to the cutting edge radius. The objective of this paper was to clarify the influence of the mechanism of the cutting tool geometry on the surface topography in the micro-milling process. Four different cutting tools including two two-fluted end milling tools with different helix angles of 15° and 30° cutting tools, as well as two three-fluted end milling tools with different helix angles of 15° and 30° were investigated by combining theoretical modeling analysis with experimental research. The tool geometry was mathematically modeled through coordinate translation and transformation to make all three cutting edges at the cutting tool tip into the same coordinate system. Swept mechanisms, minimum uncut chip thickness, and cutting tool run-out were considered on modeling surface roughness parameters (the height of surface roughness Rz and average surface roughness Ra) based on the established mathematical model. A set of cutting experiments was carried out using four different shaped cutting tools. It was found that the sweeping volume of the cutting tool increases with the decrease of both the cutting tool helix angle and the flute number. Great coarse machined surface roughness and more non-uniform surface topography are generated when the sweeping volume increases. The outcome of this research should bring about new methodologies for micro-end milling tool design and manufacturing. The machined surface roughness can be improved by appropriately selecting the tool geometrical parameters.

In order to reduce the losses caused by tip-leakage flow, axisymmetric contouring is applied to the casing of a two-stage unshrouded high pressure turbine (HPT) of aero-engine in this paper. This investigation focuses on the effects of contoured axisymmetric-casing on the blade tip-leakage flow. While the size of tip clearance remains the same as the original design, the rotor casing and the blade tip are obtained with the same contoured arc shape. Numerical calculation results show that a promotion of 0.14% to the overall efficiency is achieved. Detailed analysis indicates that it reduces the entropy generation rate caused by the complex vortex structure in the rotor tip region, especially in the tip-leakage vortex. The low velocity region in the leading edge (LE) part of the tip gap is enlarged and the pressure side/tip junction separation bubble extends much further away from the leading edge in the clearance. So the blocking effect of pressure side/tip junction separation bubble on clearance flow prevents more flow on the tip pressure side from leaking to the suction side, which results in weaker leakage vortex and less associated losses.

The powder preparation, material properties, the cutting characteristics and parameter selection for a nickel base superalloy FGH97 are summarized in this paper. It introduces the influence of various elements on the properties of the alloy, the ideal tool materials is coated cemented carbide tool and PCBN ceramic cutting tool. Generally we can choose the rake angle of 0°~10°, clearance angle of 6°~12°, cutting edge angle of 30°~60°, distortion angle of 0.5°~3°, tool cutting edge inclination angle of-10°~-20°. The optimal parameters for machining superalloy is axial cutting depth (range from 0.15~0.20mm), radial cutting depth (range from 10~20mm), the cutting speed (range from 40~60m/min), feed per tooth (range from 0.08~0.10mm/z).

A new design method to achieve the laminated Ti-Al-Mg composites by stack processing with magnesium alloy plate, aluminum powder, titanium mesh and vacuum hot-pressed sintered. Sintering laminated material in different sintering temperature. The microstructure, ingredient, structure of laminated material and the interface of Ti-Al, Mg-Al were analyzed by SEM and EDS. Test results show that the optimum sintering temperature is 550 oC, and after sintered the aluminum powder and magnesium alloy plate hang together relatively tight by slight interface reaction, and aluminum powder can able to better coating the titanium mesh within the matrix. Mechanical property test found that titanium mesh is role-playing the reinforcement in laminated material, and makes the mechanical properties of laminated material improving significantly.

Three kinds of dimensional simplified models were established according to the structure properties of interpenetrating network composites. The cutting process of INC with different structure parameters were calculated by finite element method. The random properties of cutting forces were also analyzed. It is shown that cutting forces would increase when reinforced phase is cut. Micro cracks are liable to be caused on interfaces between two phases. The structure parametersd、α、βhave great effects on cutting forces and cause random fluctuation which cause random properties for INC cutting process.

In normal temperature, the effect of rolling motion and extrusion stress will lead to the occurrence of subgrain size refinement, changes of the dislocations and phase transition caused by plasticity, which will change the mechanical properties of the workpiece’s material on the surface layer and directly affect the fatigue strength and service life of the workpiece. In this paper, the residual stress of Cr12 after rolling processing by different rolling pass and contact stress are studied through experiments. Through the analysis of the test results, it is shown that: with the increase of rolling pass, the residual stress on the workpiece surface layer increase continuously, after rolling 3 passes, the residual stress will no longer continue to increase and remain stable. When the contact stress is less than 717 MPa, the residual stress increase obviously, and when it reaches 717 MPa, the residual stress keep relatively stable state with the increase of contact stress. In the depth direction, the residual stress decreases with the depth, and the maximum residual stress may appear at a certain depth from the surface.

Because of the contact deformation, the inclination angle of the contact face is decreased gradually when contact and deformation. Base on the change of inclination angle of the contact surface, the concept "friction repose angle" set out. The tangent of the initial inclination angle of two asperities is three time of the tangent of the "friction repose angle". The relationship set up a bridge between the initial surface geometric configuration (can be detect) and the configuration which after the deformation (can not be detect). Static Friction Coefficient is the max value of Kinetic Friction Coefficient before the deformation process of instantaneous contact surface. The Ratio of Kinetic and Static Friction Coefficient distribute from 0.771 to 0.9117 and were inversely proportional to the inclination angle of the contact face .Kinetic Friction Coefficient is the average friction coefficient of the deformation process of instantaneous contact surface. In the sandstone, the value of Kinetic Friction Coefficient which more than 0.5546 is because of the coupling of different classes zigzag-shape surface asperities mostly. The study puts forward the new ideas "dynamic deformation tribology" which will promote the development of the Tribology.

In this work, the blades of shot-blasting machine were fabricated by high-chromium cast irons using investment cast processing to control different cooled rate in order to achieve solidification unidirectionally. The microstructure of oriented M7C3 carbides was simulated and revealed using deep itching methods. The rod-like M7C3 carbides in longitudinal direction and lath-shaped M7C3 carbides in transverse and vertical direction are observed. When the long axis of the carbide rods is paralleling to the shots flow direction, high-chromium cast irons possess higher hardness and fracture toughness than that of perpendicular to the shots flow direction. The results reveal that the blades possessing oriented M7C3 carbides in longitudinal direction exhibit excellent impact-abrasive wear resistance than that of in transverse and vertical direction. The wear surface was examined by scanning electron microscopy for identifying the impact wear mechanisms.

The band structures and electronic structures of pristine and Ag-doped zinc blende ZnS were calculated with the ab-initio ultra-soft pseudopotential plane wave approximation method based on density functional theory (DFT). The results show that Ag- doping narrows the band gap of ZnS and the acceptor impurity level is introduced by importing impurity Ag. It is pointed out that the acceptor level is hybridization due to the overlapping of the Ag-4d and S-3p. By analysis of Mulliken populations, Zn- S bond has strong covalence in ZnS and the covalence of bond Ag-S is weakest after Ag-doped.

The wear-resistance performance of machined surface is an important factor in the evaluation of surface quality and precision in aerospace manufacturing industry. By using high-speed Ring-Block friction and wear machine (MRH-3), the influence of cutting parameters in milling aluminum alloy 7050-T7451 on wear-resistance of machined surface including friction coefficient and wear quantity are experimentally investigated. The wear-resistance is particularly sensitive to cutting speed and feed rate. The friction coefficient has marked drop trends as cutting speed increases. The influence of cutting speed on wear quantity is more complicated and the tendency of wear quantity was ascend in first and descend at last (v>900/min). The results show that the influence of cutting parameters on wear-resistance was also positively correlated with surface roughness and work-hardening of machined surface. The high work-hardening and surface quality had the promoting effecting on wear-resistance. The experiment and analysis results show that the machined surface by high speed cutting and lower feed rate has more superior in surface quality and wear-resistance performance comparing with conventional cutting speed.

Powder metallurgy (PM) nickel-based superalloy is regarded as one of the most important aerospace industry materials, which has been widely used in advanced turbo-engines. This work presents an orthogonal design experiments to study the cutting force and cutting temperature variations in the face milling of PM nickel-based superalloy with PVD coated carbide tools. Experimental results show that with the increase of feed rate and depth of cut, there is a growing tendency in cutting force, with the increase of cutting speed, cutting force decreases. Among the cutting parameters, feed rate has the greatest influence on cutting force, especially when cutting speed exceeds 60m/min. With the increase of all the cutting parameters, cutting temperature increases. However the cutting temperature increases slightly as the increasing of feed rate. Tool failure mechanisms in face milling of PM nickel-based superalloy are analyzed. It is shown that the breakage and spalling on the cutting edge are the most dominate failure mechanisms, which dominates the deterioration and final failure of the coated carbide tools.

Powder metallurgy (PM) nickel-based superalloy is regarded as one of the most important aerospace industry materials, which has been widely used in advanced turbo-engines. This paper presents an experimental study of high speed milling of powder metallurgy nickel-based superalloy with PVD (TiAlN-TiN) coated carbide tools. Experimental measurements of milling temperature and milling force were performed. Then the surface roughness and tool wear were analyzed and discussed under dry machining conditions. The results might be helpful to guiding the selection and design of tool materials and control of tool wear in high speed milling PM nickel-based superalloy.

Powder metallurgy (PM) nickel-based superalloy is regarded as one of the most important aerospace industry materials, which has been widely used for engine components. As the demands of the service performance increase, the surface characteristics are becoming more and more important. However, the machined surface of PM nickel-based superalloy is easily damaged due to its poor machinability. A series of milling experiments in a wide range of speeds were carried out to investigate the effects of dry milling parameters on the surface characteristics of PM nickel-based superalloy. The machined surface is evaluated in terms of surface roughness and work hardening. The results show that, milled surface characteristics of PM nickel-based superalloy are sensitivity to the cutting speeds. The machined surface roughness increases with increase of the cutting speed, but with further increase of cutting speed between 70 to 90 m/min and 150 to 170 m/min two decreases in surface roughness appear. For work hardening, it can be seen that the machined workpiece surface hardens seriously.

The present paper is an experimental investigation on the machinability of powder metallurgy (PM) nickel-based superalloy during drilling using high-speed steel (M42) drills. The effect of machining parameters on the cutting force, cutting temperature and tool wear were investigated during the experimentation. The effect of machining parameters on the tool wear was examined through SEM micrographs. The research work findings will also provide useful economic machining solution by utilizing economical high-speed steel drills during drilling processing of powder metallurgy nickel-based superalloy, which is otherwise usually machined by costly coated carbide tools or CBN tools. The present approach and results will be helpful for understanding the machinability of powder metallurgy nickel-based superalloy during drilling for the manufacturing engineers.

An experimental investigation was carried out to understand the behavior of a powder metallurgy nickel-based superalloy when machined with sialon ceramic insert tools. Turning experiments were carried out at different cutting speeds and feed rates while depth of cut was kept constant. Cutting tool performance was evaluated with respect to temperature and cutting forces generated during turning, and tool wear. The sialon ceramic cutting tool showed high performance when increasing cutting speed, the machining experiments showed that sialon ceramic tools performed better at cutting speed up to 80 m/min. Abrasion and adhesion was the dominant wear mechanisms. Chipping on the tool rake and flank faces, as well as catastrophic failure under thermal shock and mechanical loading, was also observed in experiments. As cutting temperature was very high when turning powder metallurgy nickel-based superalloy, good high-temperature strength and thermal shock resistance were indispensable to the cutting tools for machinging this kind of material.

Powder metallurgy (PM) nickel-based superalloy is regarded as one of the most important aerospace industry materials. A series of turning tests in a wide range of speeds with different inserts were carried out to select the proper tool material. Then, the effect of cutting parameters on the cutting force, cutting temperature and tool wear was investigated for the selected insert. The effect of cutting parameters on the tool wear was examined through SEM and TEM micrographs. The experiential functions of tool life, cutting force and cutting temperature were developed. Finally, the cutting parameters in PM nickel-based superalloy dry turning were optimized based on tool life-efficiency contour analysis. The present approach and results will be helpful for understanding the machinability of PM nickel-based superalloy during dry turning for the manufacturing engineers.