Search

Purpose To evaluate the effect of conbercept on the expression of long noncoding RNAs (lncRNAs) and mRNAs in the fibrovascular membranes of proliferative diabetic retinopathy (PDR) patients. Methods Twenty patients, diagnosed with PDR, who underwent pars plana vitrectomy (PPV), were recruited for this study. Ten patients were treated for PPV alone (Control Group), and the others received conbercept injections before PPV (Treated Group). The fibrovascular membranes were harvested during surgery. Expression of lncRNAs and mRNAs in the membranes was tested using lncRNA Arrays. Bioinformatics analyses were performed to identify the related biological modules and pathways of the differentially expressed genes. A lncRNA/mRNA coexpression network was built to identify the correlations between lncRNAs and mRNAs. Real-time PCR was conducted to verify the microarray results. Results We identified 427 differentially expressed lncRNAs, of which 263 were upregulated and 164 were downregulated. Gene ontology (GO) analysis indicated that these lncRNAs-coexpressed mRNAs targeted various metabolic processes, especially the gluconeogenesis. Kyoto Encyclopaedia of Genes and Genomes (KEGG) results indicated that 16 pathways had significant differences in gene expression, including gluconeogenesis, HIF-1 signalling pathway, NOD-like receptor pathway, etc. The lncRNA/mRNA coexpression network revealed that many differentially expressed lncRNAs were enriched in the HIF-1, TNF-α and NOD-like receptor pathways. LincRNAs were the largest category and further bioinformatics analysis implied that these lincRNAs-coexpressed mRNAs were mainly involved in PDR-related biological processes and pathological pathways. Conclusion Conbercept treatment can change the expression profiles of lncRNAs and mRNAs in the fibrovascular membranes of PDR patients. A complete understanding of the relationship between lncRNAs and anti-VEGF drugs may contribute to new therapeutic regimen for PDR.

To investigate the change on phacoemulsification combined with intraocular lens implantation on inflammatory factors IL-2, IL-6, hs-CRP,TNF-alpha; oxidative stress response indexes MDA, CAT, SOD, GSH-Px; peripheral blood hemorheologic index WHV, WMV,PV, PCV, FIB in diabetic cataract patients.An observational study.Department of Ophthalmology, the Second Hospital of Shandong University, Jinan, China, from January 2015 to July 2017.One hundred anf fifty-two diabetic cataract patients (160 eyes) were randomly divided into observation group and control group, each with 76 cases (80 eyes). The control group was treated with conventional therapy, while the observation group was treated with phacoemulsification combined with intraocular lens implantation on the basis of conventional treatment. After one month of treatment, the patients were tested for IL-2, IL-6, hs-CRP, TNF-alpha;, MDA, CAT, SOD, GSH-Px, WHV, WMV, PV, PCV, FIB.After one month of treatment, the levels of IL-2, IL-6, hs-CRP and TNF-alpha; were lower in the observation group (p0.001); the levels of SOD, GSH-Px and CAT were higher in the observation group (p0.001), while MDA level was higher in the control group (p0.001); the levels of WHV, WMV, PV were lower in the observation group (p0.001), and there was no significant difference in the levels of PCV and FIB between the two groups (p = 0.794 and 0.838, respectively).Phacoemulsification combined with intraocular lens implantation can improve the level of aqueous inflammatory factors and oxidative stress response indexes in diabetic cataract patients and improve their level of hemorheological indexest.

Purpose: One purpose of this study was to examine if expression of the thymosin β10 (TB10), thymosin β4 (TB4), and VEGF165 isoform genes would change in response to hypoxia in monkey choroidal retinal endothelial cells (RF/6A). We also sought to determine if overexpression of the TB10 gene could inhibit VEGF165 mRNA expression, autocrine VEGF production, and tube formation in hypoxic RF/6A cells. Methods: An adenovirus vector, Ad-TB10, was constructed to deliver the human TB10 gene. Under hypoxic conditions, TB10, TB4, and VEGF165 mRNA were measured using real-time PCR, and VEGF protein expression was evaluated by ELISA. For tube formation assays, the RF/6A cells were transfected with Ad-TB10 and exposed to hypoxia for 4 h. Results: VEGF165 mRNA was 2- and 5.8-fold increased when the RF/6A cells were exposed to hypoxia for 2 and 4 h, respectively. TB10 mRNA decreased at 2 h and increased to a baseline level at 4 h, while TB4 mRNA level increased slightly by 2 and 4 h. Increased VEGF165 mRNA was down-regulated by transfected Ad-TB10, and ELISA results showed that VEGF protein levels increased 2.4-fold after 4-hour hypoxia, and decreased 2-fold after transfection with Ad-TB10. Hypoxia also induced tube formation of the RF/6A cells. This was significantly reduced by Ad-TB10. Conclusion: These data indicate that (1) TB4 and TB10 mRNA expression in RF/6A cells present different changes under 2- and 4-hour hypoxia, and (2) TB10 may be an effective inhibitor of angiogenesis by inhibiting VEGF expression and autocrine protein production.

Mo ions extracted from a metal vapor vacuum arc ion source were implanted into H13 steel with a high implantation dose of 5 × 1017 cm−2 and a pulsed ion beam flux of about 300 μA cm−2. An optical interference microscopy and pin on disc apparatus investigated the wear and friction characteristics of the steel. The Mo concentration depth profile was measured by using Rutherford backscattering spectroscopy. It was observed by X-ray photoelectron spectroscopy and grazing angle X-ray diffraction that carbide of Mo appeared in the doped region. The concentration depth profile and microstructure analysis could serve to illuminate the wear resistance improvement mechanisms of the Mo implanted steel.

Ultra-thin (5 nm) Fe catalyst films were deposited by a metal vapor vacuum arc (MEVVA) ion deposition system. The surface morphologies of the films were controlled by varying the angular relation of the substrate surface with respect to the incoming vapor direction. The Fe films grown with the incident flux at an angle of 30° with respect to the surface were shown to be smooth and after thermal treatment in NH3 the particles with a narrow size distribution and high N/Fe atom ratio were followed. When they were used to synthesize carbon nanotube arrays, pure and well-aligned multi-walled carbon nanotubes were obtained.

The thermal reaction of Co film deposited on Si(111) surfaces by a high current filter metal vacuum arc (FMEVAD) system has been studied. After deposition the films were annealed over the 400-900 degrees C temperature range for 30 min. Rutherford backscattering spectrometry (RBS) was used to characterize the elemental depth distributions in the films subjected to different annealing temperatures. Ordered chemical phases were determined by glancing-incidence X-ray diffraction (GIXRD) and the morphology was determined by cross section transmission electron microscopy (TEM). The results show that the phases formed are Co2Si at 400 degrees C, CoSi + Coo at 500 degrees C, CoSi + CoSi2 at 600 degrees C and CoSi2 at (700-800 degrees C). At 900 degrees C, CiSi(2) was formed with a mixture of cubic cobalt and probably an amorphous cobalt oxide surface layer. The interface morphology was a rough cusp-like crenelation at 600 degrees C which became less pronounced after annealing at 800 degrees C. (c) 2006 Elsevier B.V. All rights reserved. (Less)

Metal Vapor Vacuum Arc (MEVVA) ion source and ion implanter developed in Beijing Normal University (BNU) is introduced. The application in surface modification of materials with MEVVA ion implanter is reviewed.

H13 steel samples were implanted with tungsten using a metal vapor vacuum arc (MEVVA) ion source, with an implantation dose of 1×1017 cm -2, an extraction acceleration of 30 kV and pulsed ion beam fluxes of between 0.3 mA·cm -2 and 6 mA·cm -2. The surface mechanical properties and microstructure for the W-implanted samples was characterized by the Rutherford backscattering spectroscope (RBS) and a high voltage electron microscope (HVEM). Experimental results of wear and hardness indicated that the hardness and wear of H13 steel increased when the voids were produced by tungsten ion implantation with a high pulsed current density. Forming causes for voids and their influence on the tungsten concentration depth profile in the implanted H13 steel and the surface mechanical properties were discussed in terms of spike theory.

SiO2 thin films containing nanocrystalline Si (nc-Si) and Er ions have been fabricated by using a metal vapor vacuum arc (MEVVA) ion source. Photoluminescence (PL) properties of the films were studied as the function of the Er ion dose. The PL intensity was found to be strongly enhanced by incorporating nc-Si in the films. The intensity of the 1.54 μm luminescence peaks firstly increases with the increasing of the Er concentration, arriving at a maximum with Er concentration of 8.0 at.% at room temperature (RT). Then PL yields decreased with further increase in Er ion dose. A mechanism about energy transferring between the photogenerated carrier in the nc-Si and Er3+ in SiO2 has been investigated.

H13 steel samples were implanted with tungsten and the improvement in surface mechanical properties was investigated. The tungsten ion implantation was done using a metal vapor vacuum arc (MEVVA) ion source, with an ion current density of 15 μA cm−2. The implantation of tungsten showed a superior wear resistance surface. The relationship between surface mechanical property and microstructure for the tungsten-implanted samples was characterized by Rutherford backscattering spectroscopy (RBS), grazing-angle X-ray diffraction (GAXRD) and X-ray photoelectron spectroscopy (XPS). The tungsten carbides and tungsten oxides were observed in the doped region. The experimental results have shown that the formation of WC and WO3 improved the wear resistance of H13 steel.

In this paper nanometer TiN/AlN multilayers have been prepared on silicon substrate by filtered vacuum arc deposition. The structures of the nanometer TiN/AlN multilayer have been studied with X-ray diffraction. The 12 nm TiN/AlN multilayer exhibits (1 1 1) and (2 0 0) texture, and the 6 and 2 nm thick multilayer exhibits only (2 0 0) texture. The multilayer deposited at −100 V bias exhibits a (1 1 1) texture, whilst the multilayer deposited at 0 V bias exhibits a (2 0 0) texture. At higher bias voltage the peaks become sharper and have a higher intensity in low angle X-ray diffraction. The hardness and elastic modulus of multilayer are dependent on period of multilayer. The hardnesses of the TiN/AlN multilayers are higher than the hardness value suggested by a simple rule of mixture. The peaking hardness of nanometer TiN/AlN multilayers at period of 2 nm was about 42 GPa, much higher than that of 12 nm. The wear resistance of the nanometer TiN/AlN multilayers has also been studied.

High quality tetrahedral amorphous carbon films (ta-C) have been prepared on silicon and M2 steel substrate by filtered cathodic vacuum arc deposition. The structures, mechanical properties, adhesion and wear resistance of the tetrahedral amorphous carbon films have been investigated. The hardness and elastic modulus of the tetrahedral amorphous carbon films are determined by nano-indentation tests. The results show that the hardness and elastic modulus of the tetrahedral amorphous carbon films are 79 and 431 GPa, respectively. The friction performance of the tetrahedral amorphous carbon films was also studied. The coefficient of tetrahedral amorphous carbon film on substrate of M2 steel is 0.20, and stable up to 2500 cycles and the wear rate of tetrahedral amorphous carbon film is 1.233 × 10 −8 mm 3 /N m for an applied load of 5 N and 2500 cycles.

Tetrahedral amorphous carbon films have been widely recognized as being wear-resistant coatings with a low friction coefficient, but their tribological behavior strongly depends on the tribotesting conditions and the nature of the coating, which depends on the technique used for film deposition. In this paper the structure, mechanical properties and wear resistance of the tetrahedral amorphous carbon films deposited on silicon, W18Cr4V high-speed steel and Cr18Ni9 stainless steel substrates by pulsed filtered catholic vacuum arc system have been investigated. The wear test results show: the tetrahedral amorphous carbon films have wear coefficient of 0.14–0.20 and wear rate of 5.833×10 −9 mm 3 /N m for an applied load of 5 N and 6000 cycles against sapphire ball. The effects of substrate, applied load, frequency and film thickness on coefficient of friction have been studied.

Erbium doped SiO 2 thin films containing Si nanocrystals were fabricated by Si and Er dual implantation into SiO 2 using a metal vapor vacuum arc (MEVVA) ion source. Photoluminescence (PL) intensity was strongly enhanced by the incorporation of nanocrystalline Si (nc-Si) in the SiO 2 films. For samples implanted with a fixed Er dose, there is an optimum Si dose to achieve a maximum 1.54 μm PL peak intensity, and likewise for samples implanted with a fixed Si dose, there is an optimum Er dose to achieve a maximum PL intensity. These results were discussed in terms of energy transfer mechanisms between the photogenerated carriers in the nc-Si and Er ions in the SiO 2 matrix.

A thick ceramic coating was prepared on Al–Cu–Mg alloy by microarc discharge in aqueous solution. The tensile properties of the alloy before and after microarc oxidation (MAO) surface treatment were tested, then the fractography and morphology of ceramic oxide coatings were investigated using scanning electron microscope (SEM). It is showed that the tensile properties of aluminum alloy have smaller change after the alloy has undergone microarc discharge treatment. For all specimens with different thickness coatings, the decreases of yield strength, tensile strength and elastic modulus are less than 5%, and the contraction of area rises while the elongation slightly decreases. After the coatings are polished, the tensile properties of the alloy are improved rather small. The surface of tensile specimens uniformly remains a large quantity of tiny fragments of alumina coatings. That implies that the ceramic coating has good adhesion with aluminum alloy substrate.

A determination of the phase constituents of ceramic coatings produced on Al–Cu–Mg alloy by microarc discharge in alkaline solution was performed using x-ray diffraction. The profiles of the hardness, H, and elastic modulus, E, across the ceramic coating were determined by means of nanoindentation. In addition, a study of the influence of microarc oxidation coatings on the tensile properties of the aluminium alloy was also carried out. The results show that the H-and E-profiles are similar, and both of them exhibit a maximum value at the same depth of coating. The distribution of the α-Al2O3 phase content determines the H- and E-profiles of the coatings. The tensile properties of 2024 aluminium alloy show less change after the alloy has undergone microarc discharge surface treatment.

In this work, high concentration erbium doping in silicon-rich SiO2 thin films is demonstrated. Si plus Er dual-implanted thermal SiO2 thin films on Si substrates have been fabricated by using a new method, the metal vapor vacuum arc ion source implantation with relatively low ion energy, strong flux and very high dose. X-Ray photoelectron spectroscopy measurement shows that very high Er concentrations on the surfaces of the samples, corresponding to ∼10 at.% or the doping level of ∼1021 atoms cm−3, are achieved. This value is much higher than that obtained by using other fabrication methods such as the high-energy ion implantation and molecular beam epitaxy. Reflective high-energy electron diffraction, atomic force microscopy and cross-section high-resolution transmission electron microscopy observations show that the excess Si atoms in SiO2 matrix accumulate to form Si clusters and then crystallize gradually into Si nanoparticles embedded in SiO2 films during dual-ion implantation followed by rapid thermal annealing. Er segregation and precipitates are not formed. Photoluminescence at the wavelength of 1.54 μm exhibits very weak temperature dependence due to the introduction of Si nanocrystals into the SiO2 matrix. The 1.54-μm light emission signals from annealed samples decrease by less than a factor of 2 when the measuring temperature increases from 77 K to room temperature.

Erbium and silicon were dual implanted into thermally grown SiO2 film on Si by a metal vapor vacuum arc ion source, followed by rapid thermal annealing at 900–1100°C for 20 s. 1.54 μm photoluminescence was observed at room temperature and 77 K. Rutherford backscattering spectrometry shows that Er ions mainly distribute near the surface, and the highest Er concentration exceeds the magnitude of 1021 cm−3. Needle nanocrystalline silicon (nc-Si) is formed on the surface of the implanted layer. X-ray photoelectron spectrum analyzed the concentration proportion of Er, Si, SiO2 in the implanted layer, excess Si concentration ranges from 11.1% to 22.7%. The Er3+ acts as an isolated ion luminescence center, most excitation energy may be obtained from the electron–hole combination at the interface of nc-Si/SiO2 (or c-Si/SiO2), and then the energy transfer to Er3+, results in the light emission of 1.54 μm.

A new method, metal vapour vacuum arc ion source implantation, has been developed to synthesize Er-doped Si-rich SiOx thin films under relatively low implanted ion energies and very high doses. An Er concentration as high as ~1021 atoms cm-3 in the Si oxide layer can be reached. Reflection high-energy electron diffraction and cross section transmission electron microscopic observations show that the excess Si atoms in the SiO2 matrix cluster and crystallize gradually into nano-size grains with an average size of 4.5 nm during the rapid thermal annealing process after dual-implantation. The sample emits a 1.54 µm wavelength luminescence signal, the intensity of which decreases by only a factor of two as the measuring temperature increases from 77 K to 300 K, showing very weak temperature quenching.

Microarc oxidation is an advanced coating process to deposit thick, hard ceramic oxide coatings on metal surfaces. In this paper, a ceramic oxide coating of 30μm was prepared on TA2 pure titanium by alternating-current microarc oxidation in aluminate solution. Its morphology, composition and structure were characterized by scanning electron microscopy, X-ray diffractometry, Raman spectroscopy. The Al, Ti, O concentration profiles across the coating were determined by energy dispersive spectroscope. The outer layer of the coating is composed of a large amount of TAl 2 O 5 and a little rutile type TiO 2 compounds. But the rutile content in the inner layer is much higher than in the outer layer while the TiAl 2 O 5 content decreases obviously in the inner layer. All of these oxides derive from a rapid solidification of the melt in microarc discharge zone. The Al atoms from the aqueous solution have diffused to the coating/titanium substrate interface, but are enriched in the outer layer. However, the oxygen and aluminum atoms have not diffused into the unoxidized titanium substrate, even near the coating/substrate interface. This facilitates maintaining mechanical properties of pure titanium substrate after microarc oxidation treatment on titanium surface.

A dense ceramic coating up to 130μm thick was deposited on high silicon cast aluminum alloy by microarc discharge in silicate electrolyte. Its microstructure and composition were analyzed by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and phase identification was performed by X-ray diffraction (XRD). In addition, the distributions of hardness, H, and elastic modulus, E, across the ceramic coating were determined by nanoindentation method. The coating has a three-layer structure. The profiles of H and E in the coating are similar. From the surface to the inner layer of the coating, H and E gradually increase. The inner layer is dense and hard, in which the H and E can reach about 15 GPa and 250 GPa, respectively. This coating consists of mullite, γ-Al 2 O 3 , γ-Al 2 O 3 and amorphous SiO 2 phases. The surface layer enriched in Si element has a high fraction of amorphous SiO 2 , where the Si element comes mainly from the electrolyte rather than the alloy substrate. However, the Si element from Al-Si substrate enhances the formation of mullite phase in the coating.

Purpose: This study measure the changes in Anterior Chamber Depth (ACD) and Axial Length (AL) after scleral buckle (SB) surgery or Pars Plana Vitrectomy (PPV) for the repair of rhegmatogenous Retinal Detachment (RD). Methods: 102 eyes of patients undergoing rhegmatogenous retinal detachment repair were prospectively reviewed. 49 eyes of 49 patients scheduled to undergo SB surgery and 53 eyes of 53 patients scheduled to undergo PPV. ACD and AL were measured by spectral-domain optical coherence tomography (SD-OCT) and biometry, 1 day before surgery as well as 3 and 4 months postoperatively. Results: ACD was not decreased significantly for patients undergoing PPV surgeries 3 months postoperative (p=0.0843) and 4 months postoperative (p=0.2616). ACD was observed to decrease significantly 3 months (p=0.029) and 4 months (p=0.0027) postoperatively for patients undergoing SB surgeries. AL increased significantly after SB surgery 3 months postoperative (p=0.0020) and 4 months postoperative (p=0.0001). AL not increased significantly after PPV surgery 3 months postoperative (p=0.0863) and 4 months postoperative (p=0.1576). The level of statistical significance was set at p

Polyethylene terephthalate (PET) has been modified by Ag, Ti, Cu and Si ion implantation with a dose ranging from 1×1016 to 2×1017 ions/cm2 using a metal vapor vacuum arc (MEVVA) source. The electrical properties of PET have been improved by metal ion implantation. The resistivity of implanted PET decreased obviously with an increase in ion dose. The results show that the conductive behavior of a metal ion implanted sample is different from Si-implantation samples. In order to understant the mechanism of electrical conduction, the structures of implanted layer were observed in detail by XRD and TEM. The nano carbon particles were dispersed in implanted PET. The nano metallic particles were built up in metallic ion implanted layers with dose range from 1 × 1016 to 1 × 1017 ions/cm2. The nanometer metal net structure was formed in implanted layer when a dose of 2 × 1017ions/cm2 is reached. Anomalous fractal growths were observed. These surface structure changes revealed conducting mechanism evolution. It is believed that the change would result in an improvement of the conductive properties. The conducting mechanism will be changed with increasing metal ion dose.

The corrosion resistance of C+Mo dual-implanted H13 steel was studied using multisweep cyclic voltammetry. The phase formation conditions for corrosion resistance and its effects were researched. The super-saturation solid station solution of Mo+ and C+ atoms was formed in Mo+C dual implanted steel. Precipitate phase with nanometer size Fe2Mo, FeMo, MoC, Fe5C3 and Fe7C3 were formed in dual implanted layer. The passivation layer consisted of these nanometer phases. The corrosion resistance of the dual implanted layer was better than that of single Mo implantation.J p of the Mo implanted sample is 0.55 times that of H13 steel. The corrosion resistance of the dual implantation was enhanced when ion dose increased. When the Mo+ ion dose was 6×1017/cm2 in the dual implantation,J p of the dual implanted sample was only 0.11 times that in H13 steel. What is important is that pitting corrosion properties of dual implanted steel were improved obviously.

A dense ceramic oxide coating, about 50 µm thick, was prepared on a Ti–6Al–4V alloy by alternating current microarc oxidation in an aluminate solution. Its microstructure and phase composition were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The oxide coating contains two layers: an outer layer and a dense internal layer. The coating is mainly composed of TiO2 rutile and TiAl2O5 spinel phases. In the outer layer coating, the TiAl2O5 fraction is much higher than the rutile fraction. However, in the internal layer, rutile becomes the main phase while the TiAl2O5 fraction decreases significantly. During microarc oxidation, local melt–solidification processes take place in the coating, however, the microstructure of the Ti–6Al–4V substrate near the coating/metal interface is not changed. Aluminium from the solution is enriched in the outer layer coating, although it has also diffused into the interior of the coating.

Si 3 N 4 / Si (1 0 0), SiO 2 / Si (1 0 0) and SiO 2 / Si (1 1 1) wafers were implanted by keV Co ions under technical conditions to form thin silicide surface films. A metal vapour vacuum arc (MEVVA) source was employed to produce a high fluence of Co ions that was just sufficient to remove the oxide/nitride overlayer by sputter erosion. This high-fluence implantation under technical vacuum introduces foreign atoms into the implanted layer. The behaviour of these impurities following ∼900°C heat treatment in a N2 atmosphere has been studied. Elemental redistributions, crystal recovery, phase formation and electric properties were analysed. The results show that the annealing leads to an increase in crystal ordering within the implanted layer and stable phase formation, as indicated by a reduction in the channeling signal and a decrease in electrical resistivity. In the case of nitride-coated samples, the heat treatment leads to a reduction in the residual carbon and nitrogen in the samples, while the oxygen content is largely unchanged. In contrast, a remarkable increase in the carbon and especially the oxygen contents is observed in the case of the samples with oxide overlayers, and the Co shows a tendency to spread to greater depths.

The approach to quasi equilibrium sputtering of transition elements Co, Er, V and Ni during high-fluence implantation of Si(1 1 1) using a metal vapour vacuum arc (MEVVA) source has been studied by time of flight-energy elastic recoil detection analysis (ToF-E ERDA) and scanning electron microscopy (SEM). The partial sputter yield of the implanted species was determined from the change in the content of the implanted species with the implanted ion fluence. The partial sputter yield of Co exhibits a step-like rise to ∼0.4 that might be associated with a rapid segregation of Co to the surface followed by a slow exponential-like increase. Er on the other hand follows an exponential approach to the quasi-equilibrium partial sputtering yield which is indicative of no strong buildup of Er within the sputter escape depth. Additional data for Ni and V suggest also an exponential approach to quasi-equilibrium sputtering.

Polyethylene terephthalane (PET) has been modified with Ti, Ag, Si and C ions from a metal vapor arc source (MEVVA). Ti, Ag, Si and C ions were implanted with acceleration voltage 40 kV to fluences ranging from 1×1016 to 2×1017 cm−2. The surface of implanted PET darkened with increasing ion dose, when the metal ion dose was greater than 1×1017 cm−2 the color changed to metallic bright. The surface resistance decreases by 5–6 orders of magnitude with increasing dose. The resistivity is stable after long-term storage. The depth of Ti- and Ag-implanted layer is approximately 150 and 80 nm measured by Rutherford backscattering (RBS), respectively. TEM photos revealed the presence of Ti and Ag nano-meter particles on the surface resulting from the high-dose implantation. Ti and Ag ion implantations improved conductivity and wear resistance significantly. The phase and structural changes were obtained by X-ray diffraction (XRD). It can be seen that nano-meter particles of Ti precipitation, TiO2 and Ti-carbides have been formed in implanted layer. Nano-hardness of implanted PET has been measured by a nano-indenter. The results show that the surface hardness, modulus and wear resistance could be increased.

The microstructures of the microarc oxidation coatings and 2024 aluminum alloy substrate were observed using the scanning electron microscope (SEM) and the phase composition of the coatings was analyzed by X-ray diffraction (XRD). Furthermore, the profiles of the nanohardness, H, and elastic modulus, E, along the coating depth were first determined using the mechanical properties microprobe. The microarc oxidation coatings consist of two layers—a loose layer and a compact layer. The H and E in the compact layer are about 18–32 GPa, 280–390 GPa, respectively. The H and E profiles are similar, and both of them exhibit a maximum value at a same depth of the coatings. The distribution of α-Al2O3 phase content determines the H and E profiles in the coatings. The changes of α-Al2O3 and γ-Al2O3 contents result from the different cooling rates of the molten alumina in the microarc discharge channel at the different depths of the coatings. After the microarc oxidation treatment, the microstructure of the alloy substrate, even near the Al/Al2O3 interface, has not been changed.

Growth regularity of ceramic coatings formed on Al–Cu–Mg alloy by microarc oxidation was investigated, and the formation mechanism of coatings was discussed. After oxidation of several hours with linear growth, the growth rate of coatings decreases gradually. During the early stage, the sample geometrical dimension increases with oxidation. However, when the ceramic oxide coating reaches a certain thickness, the sample geometrical dimension will no longer increase although the total coating thickness keeps increasing. The oxide coatings contain a loose layer and a compact layer. The loose layer is formed first. After several hours, the compact layer begins to grow towards the Al substrate while the thickness of the loose layer changes little. The thickness of the compact layer can finally reach over 75% of the total coating thickness. After the surface loose layer is ground off, the sample dimension is approximately the same size as the sample before the treatment.

Thin (Ti,C) and (Mo,C) binary coatings were respectively formed on the surface of H13 steel by Ti + +C + and Mo + +C + dual beams deposition using filtered vacuum arc plasma deposition (FVAPD) system with three MEVVA sources. Using the three-electrode potential-kinetic polarization technique, the corrosion properties of these coatings in acetic acid and sodium acetate solutions or sodium chloride solutions were measured. The results indicate that the binary coatings fabricated by this technique have good compactness and corrosion resistance. A comparison between (Ti,C), (Mo,C) coatings and H13 steel with pure Ti coating in terms of the corrosion resistance was given. Electron diffraction and XRD results show that the structure of the binary coatings presents a mixed polycrystalline and amorphous state.

In this paper, Ni–Cr–Mo–Nb multi-element surface alloying has been investigated on a substrate of three kinds of industrial steels (industrial pure iron, low carbon steel and 304 stainless steel) by means of the double glow plasma surface alloying technique. The results showed that highly alloyed nickel-based surface alloying layers were formed on the surface of the three kinds of steels. The alloying layer was uniform, continuous and compact. The alloying layers consisted of a γ phase or γ matrix with several precipitates (P or Laves phase, and NbC carbide, etc.). A method of eliminating these precipitates has also been discussed. The corrosion resistance of the nickel-based surface alloying layer was investigated by an electrochemical method in a 3.5% NaCl and 5% HCl solution, and 200-h exposure tests in a 20% H2SO4 and 20% HCl solution. The corrosion resistance of surface alloying layer formed on stainless steel substrate was better than that of the nickel-based alloy Inconel 625 and 304 stainless steel. The experimental results indicated that this is an effective way to obtain a high quality corrosion resisting surface alloying layer on the surfaces of steels using the double glow plasma surface alloying technique.

The surface properties of Nb+C co-implanted stainless steel have been studied. The co-implantation of Nb+C ions was carried out using a modified cathode of a metal vapor vacuum arc (MEVVA) source ion implanter. The results of the experiment showed that the properties of wear resistance and the hardness in the co-implanted surface layer were improved. The dislocation network and tangle were observed by TEM. The dispersion hardening phases were determined by XRD and TEM to be Fe2Nb, Cr23C6, Cr3C2 and Fe5C2. Therefore, dispersion hardening and dislocation hardening were expected. The results were also compared with those of Nb+C ion dual implantation. This showed that there were some unique advantages to co-implantation.

The microstructure near the interface between a 2024 Al alloy substrate and a ceramic coating formed by microarc oxidation has been studied using scanning electron microscopy and energy dispersive spectrometry. Hardness and elastic modulus on the two sides of the interface were investigated using nanoindentation and Vickers microhardness measurement. The results showed that the microstructure of the substrate was not changed by application of the coating, and a hardened zone was not observed. During microarc oxidation, no remelting of the substrate occurred, but remelting of the alumina ceramic coating on the other side of the interface did take place. The mechanical properties on the two sides of the interface had obvious differences: in a certain range of coating thickness there was a gradual increase of hardness and elastic modulus from the interface to the interior of the coating, but hardness remained almost constant in the substrate.

Polyethylene terephthalate (PET) has been modified by Ag, Cr, Cu and Si ion implantation with a dose range from 1×10 16 to 2×10 17 ions cm −2 using a metal vapor vacuum arc (MEVVA) source. The electrical properties of PET have been changed after metal ion implantation. The resistivity of implanted PET decreased obviously with an increase of ion dose. When metal ion dose of 2×10 17 cm −2 was selected, the resistivity of PET could be less than 10 Ω cm, but when Si ions are implanted, the resistivity of PET would be up to several hundred Ω cm. The results show that the conductive behavior of a metal ion implanted sample is obviously different from Si implantation one. The changes of the structure and composition have been observed with transmission electron microscope (TEM) and X-ray diffraction (XRD). The surface structure is varying after ion implantation and it is believed that the change would cause the improvement of the conductive properties. The mechanism of electrical conduction will be discussed.

The influence of post-implantation annealing on the isothermal oxidation behavior of Nb implanted (3×10 17 ions/cm 2 ) Ti–48 at.%Al was investigated. The kinetics of isothermal oxidation at 900°C for 100 h in air revealed that appropriate post-implantation annealing (800°C/5 h) could remarkably further improve the oxidation resistance of the as-implanted alloy; possible mechanisms were discussed considering the results of element distribution, oxidation product and its surface morphology examined by Auger electron spectra (AES), X-ray diffraction (XRD) and scanning electron microscope (SEM). It indicated that both the eliminating of the lattice damage induced by ion implantation and element redistribution in the implanted region caused by post-implantation annealing might be responsible for the further decrease of the oxidation rate.

The electrochemical behavior of H13 steels implanted with titanium and carbon ions using MEVVA ion implantation was investigated. Anodic polarization measurement in acetic acid and sodium acetate solution was used to evaluate the corrosion resistance of steels before and after implantation. Lower corrosion current density and wider passive region were obtained on the implanted specimens. The saturated corrosion current density for implanted specimens decreased by 60–88% of that of unimplanted specimens in multi-polarization tests, indicating that the corrosion rate of the implanted surface was much lower. Scanning electron microscopy indicated that the pit density was lower on the surface of implanted specimens. The corrosion resistance was clearly improved after implantation.

Ti and Ti + C ions were implanted into H13 steel, the cross-sections of the samples were observed by transmission electron microscope (TEM). The results show that the structure of the implanted layer has greatly changed. The layer, embedded with nanometer phase of FeTi2, TiC and Fe–C compound, is formed in Ti and Ti + C ion-implanted layer. The thickness of the embedded layer is greater than that of the corresponding ion range. The structure of the double ion-implanted layers is obviously different. The wear resistance and hardness of Ti or Ti + C-implanted H13 steel increased, and the friction coefficient decreased. This indicates that unique resistance for wear and corrosion can be obtained. An even higher corrosion resistance has been found, as the layer with an embedded structure was formed in Ti or Ti + C-implanted H13 steel. The results of electrochemical measurement show that the corrosion current density decreases obviously with increase of ion dose. The corrosion current density of Ti-implanted steel with a dose 1.3×10 18 cm −2 is 5–13% of that of unimplanted steel. The corrosion behavior of Ti + C dual implantation could be further improved; the corrosion current density is 1.2% of that of non-implanted samples. The corrosion trace could not be observed on the annealing sample by scanning electron microscope (SEM), after multi-sweep cyclic voltammetry (CV) of 40 cycles were performed on it. Finally, the modification mechanism of Ti or Ti + C-implanted H13 steel is discussed.

Strong ultra-violet and visible frequency up-conversion fluorescence spectroscopy in neodymium-ion implantation single crystalline silicon at the excitation wavelengths of 625, 650, 675 and 700 nm, was experimentally investigated. The PL intensity increased with the increase in the excitation wavelength and ion fluence. The photoluminescence excitation (PLE) spectrum in the wavelength range of 500–770 nm was also studied. For 700-nm pumping, a mechanism of two-photon absorption and radiation transition process was proposed.

The cathode in a metal vapor vacuum arc (MEVVA) source was modified and co-implantation of V + C was carried out with the modified cathode. The result of the experiment shows that the properties of wear resistance on the co-implanted surface layer have been improved. The surface hardness has increased by 16 ∼ 82%, and the wear resistance is 1.4 ∼ 2.2 times that of unimplanting surface. By means of X-ray diffraction (XRD) and transmission electron microscopy (TEM), intermetallic compounds, such as FeV, Cr 2 VC 2 , Cr 23 C 6 , VC and Fe 5 C 2 , were observed. These new phases contributed to the improvement of the surface properties for implanted layer. The results were also compared with that of V + C dual implantation. It is shown that co-implantation method is more effective than dual-implantation for surface modification.

Thin (Ti, Fe, C) ternary films were formed on the surface of H13 steel by Ti + , Fe + , C + three-beam co-deposition using a filtered vacuum arc plasma deposition (FVAPD) system with three metal vapor vacuum arc (MEVVA) ion sources. Using the three-electrode potential–kinetic polarization technique, the corrosion resistance of these coatings in acetic acid and sodium acetate solutions or sodium chloride solutions was measured. The results indicate that the films formed by this technique have good compactness and high corrosion resistance. A comparison between the (Ti, Fe, C) films and pure Ti films or (Ti, Fe, C) layers formed by C + +Ti + dual implantation into H13 steel as regards the corrosion resistance is given. Reflective high-energy electron diffraction (RHEED), X-ray diffraction (XRD) and scanning electron microcopy (SEM) results show that the structure of the films present a mixed polycrystalline and amorphous state, which results in excellent corrosion resistance of the films.

On the SEM micrographs of Ti implanted H13 steel, a tree-branch-like structure can be observed. Further investigation with TEM shows that the newly formed composition is a formation of nano-meter FeTi2 phase in Ti implanted layer. The layer with a relatively high corrosion resistance has been formed in Ti implanted H13 steel with this structure. The results of electrochemical measurement show that the corrosion current density decreases obviously with an increase of ion dose. The corrosion current density in Ti implanted steel with a dose of 1.3×1018/cm2 is 8–20 times less than that of Ti implanted steel with a dose of 6×1017/cm2. The corrosion behavior of Ti implanted steel with a dose of 6×1017/cm2 could be further improved as the sample was annealed at 500°C for 20 min and the corrosion current density decreases by 48–80 times compared to that of non-implanted samples. The corrosion trace was not observed on the annealing sample by SEM, after multi-sweep cyclic voltammetry of 40 cycles were performed. This indicates that terrific corrosion resistance can be obtained after annealing for Ti implanted sample.

The partial sputtering yields of different species from silicon dioxide/Si and silicon nitride/Si during high-fluence keV Co Metal Vapour Vacuum Arc (MEVVA) irradiation are of importance for both silicide formation and interpretation of sputter profiling. Three sets of samples, nitride/Si(1 0 0), oxide/Si(1 0 0) and oxide/Si(1 1 1), have been bombarded to different normal fluences, Θ, from 1 × 1016 to 2.6 × 1018 ions cm−2. The partial sputtering yields for N and Si in the thick nitride films are ∼1.0 and ∼0.65, respectively, which indicates that the relative sputtering ratio of N/Si is ∼1.5. The partial sputtering yields for O and Si of oxide/Si(1 0 0) samples are determined as ∼1.0 and ∼0.3, respectively. Although the O and Si sputtering yields from oxide/Si(1 1 1) samples are ∼15% higher, the average sputtering ratio of O/Si is ∼3.4, the same for both sets of oxide/Si samples. As expected, the partial sputtering yield of Co, YCo(Θ), is small for low fluence implantation and increases with increasing Co fluence. At a normal fluence of ∼5 × 1017 ions cm−2, YCo(Θ) reaches the high fluence quasi-equilibrium limit, the value is very close to unity. The sputtering yield of Co reduces slightly at even higher fluences, which is associated with erosion of the sample surface.

MeV Si implantation into semi-insulating (SI) GaAs is a common technique used to create a deep doping layer. It is observed that the maximum of the carrier concentration is at a shallower depth than that of the implanted atom concentration. This unexpected phenomenon has previously been explained as depth measurement error. Based on our theoretical calculations and experiments, the phenomenon can be attributed to the effect of non-uniform stoichiometric disturbances (NSD) on the activation of implanted atoms. The effect of NSD in GaAs substrate is caused by MeV implantation. After implantation, an excess concentration of the heavier element As exists at shallower depth, while an excess concentration of the lighter element Ga is seen at greater depth. It is likely that Si atoms move more easily to Ga sites when they are heated in an As-rich environment. Excess lattice interstitials build up around the depth of the peak in the implanted Si+ concentration and prevent Si atoms from becoming activated there.

High-current metal-ion sources for the surface modification of materials have been under development at Beijing Normal University since 1988. The present paper discusses both a large-scale metal source ion implanter installed at this Institute at the end of 1995 for research and industrial applications, and a metal plasma deposition/implantation system with three filtered vacuum-arc plasma sources. The metal source implanter is equipped with three ion sources and hence can provide three beams of metal ions into a large target chamber of 80 cm diameter and 125 cm length. It allows processing of critical components with various shapes and tooling inserts. Cutting tools — such as inserts, drills, disc cutters and dies — and sophisticated components — such as rotors and stators of off-gas pumps for returnable artificial satellites — have been implanted with many different metal species to improve properties like hardness, wear resistance, coefficient of friction, fatigue strength, corrosion resistance, adhesion and to prolong lifetimes. Some good results are presented.

Depth distributions were measured of foreign atoms incorporated during the formation of thin silicide surface layers by ion beam synthesis. Si (111) wafers were implanted with Co and V ions using a pulsed Metal Vapour Vacuum Arc (MEVVA) ion source operated at 40 kV extraction voltage. Post-implantation analysis was carried out using Time of Flight-Energy dispersive Elastic Recoil Detection Analysis (ToF-E ERDA) with 60 MeV 127I10+. The results showed that addition to the metal ions, carbon and oxygen were incorporated at at.% levels, with distributions that were peaked at the surface and extended into the implanted layer. The findings suggest that incorporation of C and O is significantly influenced by the degree of silicide formation, with more continuous and stoichiometric silicides corresponding to a lower incorporation of foreign atoms.

Thin films of cobalt silicide are widely used as metallization in very large-scale integrated electronic circuits. In this study, Co ions were deposited on Si(1 1 1) wafers by a high beam current filter metal vacuum arc deposition (FMEVAD) system. Surface silicide films were formed after annealing from 500 to 700 °C for 30 min. The results show that a thin CoSi2 surface layer with both a smooth surface topography and sharp interface can be achieved by annealing at 700 °C. The CoSi phase and O contamination were observed in the samples that were annealed at lower temperatures.