Search

MgO thin films with high optical transmittance were prepared by cathodic vacuum arc deposition technique. Rutherford backscattering spectroscopy, atomic force microscopy and X-ray diffraction were used to investigate the influences of the negative pulse bias voltage on the composition, the morphology and the crystal structure of MgO thin films, respectively. AFM images show that the grain growth is influenced by high energy ions under bias voltage and that the grains deposited at the pulse bias voltage with set value of | V p | = 600 V stack densely and look the largest as compared to those prepared at different set V p . The RBS spectra indicate that the Mg/O ratio is about 0.95–1.00 in MgO thin films which is nearly the stoichiometric composition of bulk MgO. The Mg/O ratio increases with set | V p | until | V p | is 450 V, and then keeps almost unchanged with set | V p | up to 750 V. The MgO thin films have a combined orientation of (100) and (110). Below − 150 V, the (100) orientation is predominant and the intensity ratio of I 220 / I 200 increases with set | V p |.

Magnesium-oxide (MgOx) films have been prepared by a cathodic-vacuum-arc ion deposition system operated in an intermediate frequency pulse mode of substrate bias voltage at a mixed atmosphere of O2 and Ar. The O2 flow was adjusted in a range of 180-240 sccm at a fixed O2/Ar flow rate of 20. The structure, composition, morphology, and optical properties of the samples were analyzed by X-ray diffraction, Rutherford backscattering technique, atomic force microscopy, and UV-visible absorption spectra, respectively. Results show that the crystal orientation and grain size of the samples strongly depends on O2 flow rate. Growth of Magnesium-oxide films prefers MgO (200) and MgO (220) orientation at a smaller and larger O2 flow rate of 180 and 220 sccm, respectively. Transparent MgOx films used as the protective layer for alternating-current plasma display panel are obtained at optimal deposition conditions

a-SiCx:H (amorphous SiCx:H) and a-Si:H (amorphous Si:H) thin films were deposited under control of the reaction gases SiH4 + CH4 and SiH4 + H2 by plasma enhanced chemical vapor deposition, respectively. The microstructure of as-deposited a-SiCx:H and high temperature annealed α-SiCx:H (6H-SiCx:H), nc-Si:H (nano-crystal Si:H) thin films were investigated by Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and ultraviolet-visible spectroscopy. The multi-layer structure of the samples was examined by cross-section transmission electron microscope. The photoluminescence (PL) properties of the samples measured by time-resolved spectroscopy at room temperature showed that the maximum PL intensity and the minimum PL decay time were obtained for the sample annealed at 900 °C. Typical decay times of the samples were determined to be 100 ps and 10 ns by fitting with the use of a bi-exponential function. The latter decay time of our samples closes to the decay time of direct band gap semiconductor, but nearly one thousand times larger than that of porous Si, which was ascribed to the quantum confinement effect.

Dual-modal lanthanide-doped gadolinium nanoparticles (NPs), which exhibit an excellent magnetic resonance imaging (MRI) spatial resolution and high fluorescence imaging (FI) sensitivity, have attracted tremendous attention in biotechnology and nanomedicine applications. In this paper, terbium (Tb) ion doped gadolinium oxide (Gd2O3:Tb) NPs with varied Tb concentrations were synthesized by a laser ablation in liquid (LAL) method. The characterization of the structure, morphology, and composition shows that these NPs are spherical with excellent crystallinity. The effects of Tb ion concentration on the visible green fluorescence and longitudinal relaxivity were investigated, indicating that the fluorescence properties were significantly influenced by the Tb ion concentration, but all samples were still efficient T1-weighted contrast agents. Furthermore, the optimum Tb doping concentration was determined to be 1%. The cell viability, cellular fluorescence imaging and in vivo MRI of this dual-modal nano-probe were studied, with the results revealing that the Gd2O3:Tb NPs did not have a significant cytotoxic effect, making them good candidates for use as a dual-modal contrast agent for MRI and fluorescence imaging.

SiC layers were formed by implantation of C+ into silicon at 35 keV to fluence of 1 × 1018 cm−2. Thermal annealing was performed at 900 °C for various time intervals from 1 h to 8 h, and at various temperatures from 700 °C to 1200 °C for 2 h in nitrogen ambient. The phase transformation characteristics in these SiC layers were studied using FTIR spectroscopy and a de-convolution scheme of the IR spectra into amorphous SiC and β-SiC components. Further evolution of the relative amount of the various SiC phases upon annealing could be well described by classical nucleation and growth theory using a three-dimensional growth model. The overall enthalpy of the transformation was determined to be 0.18 eV/atom. A three-dimensional growth model was suggested according to the XPS experimental results of redistribution of the implanted carbon during annealing.

Electron field emission properties of tetrahedral amorphous carbon films (ta-C) with various sp3 fractions, [sp3]/([sp2]+[sp3]), prepared by magnetic filtered plasma deposition system, were investigated. The ta-C films were deposited on (100) n-Si wafer with a resistivity of 0.01–0.02 Ω cm in a substrate bias voltage Vb range from +20 V to -80 V. The relative fraction of sp3-bonded carbon in these films was qualitatively and quantitatively estimated by a fitting of the Raman and XPS spectra, respectively. Results show that ta-C films of high sp3 fraction, more than 80%, can be formed with a substrate bias voltage Vb in the range from -10 to -50 V. A remarkably low turn-on field of about 1.7 V/μm was observed for these samples. For Vb outside this range, the sp3 fraction is lower. The surface of such ta-C films was found to be smooth and uniform from the images of atomic force microscopy. The sp3 fraction of the sample is believed to be the main factor affecting field emission properties of ta-C films.

The electron field emission properties of planar SiC/Si heterostructures with various surface morphology formed by high dose C+ implantation into Si using a metal vapor vacuum arc ion source were investigated. An implant energy of 35 keV was used with doses of 8×1017, 1×1018 and 1.2×1018 ions/cm−2 with subsequent annealing in Ar at 1200 °C for various times. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy showed that a thin stoichiometric SiC surface layer is formed and the surface work function is about 4.5 eV. Atomic force microscopy indicated that the size and density of the densely distributed small protrusions formed on the surface vary with preparation conditions. Results showed that there is an optimum annealing time for the corresponding implant dose at which a remarkably low turn-on field of about 1 V/μm is observed. The density and size of the small protrusions on the surface are believed to be the main factors affecting the field emission properties.

Photoluminescence from β-SiC nanocrystals embedded in SiO 2 films at room temperature has been studied. The β-SiC nanocrystals were formed by carbon implantation into Si substrate at 35 keV with various dose, followed by post-implantation annealing at 1200 °C for 30 min in Ar ambient. Thermal dry-oxidation of the annealed samples at 1050 °C for 3 h was performed to form β-SiC nanocrystals embedded in SiO 2 films. The composition and chemical state of C and Si atoms were characterized by non-Rutherford backscattering spectrometry and Fourier transform infrared spectroscopy, respectively. FTIR results show that β-SiC nanocrystals were formed in SiO 2 films, and the amount of β-SiC nanocrystals in SiO 2 films increases with increasing of implanted dose. The photoluminescent properties of the samples were measured at room temperature with a Hitachi F4010 fluorescence spectrophotometer using a xenon lamp as an excitation source (300 nm). Two distinguishable PL bands located at around 460 and 535 nm were observed in all the samples. The PL intensity significantly depends the implanted dose, and there is a critical implanted dose of 2 × 10 17 cm −2 , at which the PL intensity reaches the largest value.

High dose carbon implantation into silicon to form a β-SiC buried layer has been performed by using a metal vapor vacuum arc ion source. The implantation energy and dose are 65 keV and 1×10 18 ions cm −2 , respectively. Post-implantation thermal annealing was carried out at 1250 °C for various time intervals in Ar ambient. The composition depth profile, chemical state of C and Si atoms, microstructure and optical properties of the samples have been studied using X-ray photoelectron spectroscopy, Fourier transform IR spectroscopy, cross-section transmission electron microscopy and spectroscopic ellipsometry. For the as-implanted sample, the carbon depth profile shows a Gaussian shape-like distribution with a maximum concentration exceeding the stoichiometric ratio. A clear redistribution of the implanted carbon from the Gaussian shape-like distribution to the two sides is observed during annealing. After annealing at 1250 °C for 10 h, a stoichiometric SiC buried layer of approximately 150 nm is formed. Results show the annealed sample is a multi-layered structure of SiO 2 surface layer/Si top layer/damaged Si layer/upper interface layer/β-SiC buried layer/lower interface layer on Si substrate. The optical constants of the β-SiC buried layer formed by ion beam synthesis are determined from simulation of the measured ellipsometric spectra (2.3–5.0 eV) using an appropriate multi-layered model and the Bruggeman effective medium approximation.

Tetrahedral amorphous carbon films have been prepared by magnetic filtered plasma deposition system. The samples were deposited with negative bias voltage V b range from +20 V to -95 V. The relative fraction of sp 3-bonded carbon in these films was qualitatively and quantitatively estimated by a fitting of the Raman and XPS spectra, respectively. Raman results show that the sp 3 fraction of the films deposited in the range from -10 V to -50 V was estimated to be more than 80%. The C 1s spectra were consistently decomposed into the two gaussian components, one is at 284.4±0.1 eV corresponding to sp 2-hybridized bonds, and another is at 285.2±0.1 eV corresponding to sp 3-hybridized bond. The sp 3 content can be quantitatively calculated from the integrated area of the respective gaussian peak divided by the total area of the spectra. The comparison of XPS with Raman analysis, the trend of qualitative variation of sp 3 content with V b is in agreement. We concluded that XPS analysis is a useful method for quantitatively calculating sp 3 content in hydrogen-free tetrahedral amorphous carbon films.

A sol-hydrothermal method has been proposed to prepare uniform and unaggregated nanocrystals of pure anatase and rutile from various acidic mediums. The phase formation, particle sizes, and morphologies varying with different acids and their concentrations at different reaction temperatures and times have been investigated using X-ray diffraction and transmission electron microscopy. The use of HCl and the effect of its concentrations on the formation of rutile phase at different temperatures for various reaction times have been described in detail. The effect of the addition of NaCl salt on particle sizes and rutile fractions has also been studied. In this work, the phase transformation from anatase to rutile in the presence of and the absence of NaCl salt has been considered both in neutral and in acidic mediums. The presence of a trace rutile in starting materials of anatase can show obvious effects on the phase transformation under hydrothermal conditions.

The localization of eye centers is a very useful cue for numerous applications like face recognition, facial expression recognition, and the early screening of neurological pathologies. Several methods relying on available light for accurate eye-center localization have been exploited. However, despite the considerable improvements that eye-center localization systems have undergone in recent years, only few of these developments deal with the challenges posed by the profile (non-frontal face). In this paper, we first use the explicit shape regression method to obtain the rough location of the eye centers. Because this method extracts global information from the human face, it is robust against any changes in the eye region. We exploit this robustness and utilize it as a constraint. To locate the eye centers accurately, we employ isophote curvature features, the accuracy of which has been demonstrated in a previous study. By applying these features, we obtain a series of eye-center locations which are candidates for the actual position of the eye-center. Among these locations, the estimated locations which minimize the reconstruction error between the two methods mentioned above are taken as the closest approximation for the eye centers locations. Therefore, we combine explicit shape regression and isophote curvature feature analysis to achieve robustness and accuracy, respectively. In practical experiments, we use BioID and FERET datasets to test our approach to obtaining an accurate eye-center location while retaining robustness against changes in scale and pose. In addition, we apply our method to non-frontal faces to test its robustness and accuracy, which are essential in gaze estimation but have seldom been mentioned in previous works. Through extensive experimentation, we show that the proposed method can achieve a significant improvement in accuracy and robustness over state-of-the-art techniques, with our method ranking second in terms of accuracy. According to our implementation on a PC with a Xeon 2.5Ghz CPU, the frame rate of the eye tracking process can achieve 38 Hz.

The localization of eye centers technique is used in several applications. In this paper, we combine the face shape model to eye center location method to obtaining robustness in eye center localization from a low-resolution image. We make use of shape regression approach and combine it to the eye-center localization using isophote curvature features which has shown its advantage from previous work. In the experiments, we use BioID datasets to test our approach for accurate eye center location and robustness to changes in illumination and pose. We demonstrate that our approach can achieve an improvement of the robustness of eye center localization while the accuracy at eye center localization e≤0.1 and e≤0.15 have achieve 0.918 and 0.977 respectively.

Xiumei Tian,1,* Fanwen Yang,1,* Chuan Yang,2 Ye Peng,1 Dihu Chen,3 Jixiang Zhu,1 Fupo He,1 Li Li,2 Xiaoming Chen11Department of Biomedical Engineering, Guangzhou Medical University, Guangzhou, Guangdong Province, People’s Republic of China; 2State Key Laboratory of Oncology in South China, Imaging Diagnosis and Interventional Center, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong Province, People’s Republic of China; 3State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, Guangdong Province, People’s Republic of China*These authors contributed equally to this workAbstract: Poor toxicity characterization is one obstacle to the clinical deployment of Gd2O3@SiO2 core-shell nanoparticles (Gd-NPs) for use as magnetic resonance (MR) imaging contrast agents. To date, there is no systematic toxicity data available for Gd-NPs prepared by laser ablation in liquid. In this article, we systematically studied the Gd-NPs’ cytotoxicity, apoptosis in vitro, immunotoxicity, blood circulation half-life, biodistribution and excretion in vivo, as well as pharmacodynamics. The results show the toxicity, and in vivo MR data show that these NPs are a good contrast agent for preclinical applications. No significant differences were found in cell viability, apoptosis, and immunotoxicity between our Gd-NPs and Gd in a DTPA (diethylenetriaminepentaacetic acid) chelator. Biodistribution data reveal a greater accumulation of the Gd-NPs in the liver, spleen, lung, and tumor than in the kidney, heart, and brain. Approximately 50% of the Gd is excreted via the hepatobiliary system within 4 weeks. Furthermore, dynamic contrast-enhanced T1-weighted MR images of xenografted murine tumors were obtained after intravenous administration of the Gd-NPs. Collectively, the single step preparation of Gd-NPs by laser ablation in liquid produces particles with satisfactory cytotoxicity, minimal immunotoxicity, and efficient MR contrast. This may lead to their utility as molecular imaging contrast agents in MR imaging for cancer diagnosis.Keywords: gadolinium, molecular imaging, cytotoxicity, immunotoxicity

Gd2O3 nanoprobes prepared by laser ablation in liquid can be used as magnetic resonance imaging contrast agent. However, their immunotoxicity in vivo remains unknown. In this article, the in vitro biocompatibility of the Gd2O3 nanoprobe was evaluated in terms of cell uptake, cell viability, and apoptosis. In vivo immunotoxicity was detected by monitoring the levels of the immunity mediator, cluster of differentiation (CD) markers in Balb/c mice. The results show that no in vitro cytotoxicity was observed, and no significant changes in the expression levels of CD206 and CD69 between the nanoprobe-injected group and the Gd-DTPA group in mice were observed. Importantly, the immunotoxicity data revealed significant differences in the expression levels of CD40, CD80, CD11b, and reactive oxygen species. In addition, transmission electron microscopy images showed that few Gd2O3 nanoprobes were localized in phagosomes by the endocytic pathway. In conclusion, the toxic effects of our Gd2O3 nanoprobe may be due to endocytosis during which the microstructure or ultrastructure of cells is slightly damaged and induces the generation of an oxidative stress reaction that further stimulates the innate immune response. Therefore, it is important to use a sensitive assay for the in vivo immunotoxicity measurements to evaluate the risk assessment of Gd2O3-based biomaterials at the molecular level.

Amorphous carbon nitride films were prepared at various substrate bias voltage V b using magnetic filtered plasma stream. The plasma stream was formed by sputtering a high-purity graphite target in nitrogen atmosphere. The incident ions energy was varied by applying different negative bias voltage on the substrate platform. The atomic bond structure and chemical states of C and N atoms in the films as a function of bias voltage were studied by Raman spectra, FTIR spectra and atomic force microscopy (AFM). The results show that amorphous carbon nitride films with larger sp 3 CN bond and sp 2 CN bond can be formed in a V b range from −60 to −120 V. The effect of incident ions energy on atomic bond structure and surface roughness of carbon nitride films was discussed.

SiC/Si heterostructures formed by C + implantation into Si with different implant energy (35 and 65 keV) were studied by spectroscopic ellipsometry (SE) and cross-section transmission electron microscopy (XTEM). The measured SE spectra (2.3–5.0 eV) were analyzed with appropriate multi-layer models and the Bruggeman effective medium approximation (B-EMA). The results showed that the measured spectra could be well simulated by using a multi-layer structure model. The thickness and composition of the layers were determined. Optical constants ( n and k values) of the buried β-SiC formed by ion beam synthesis in photon energy of 2.3–5.0 eV were first obtained by SE calculation.

Tetrahedral amorphous carbon films (ta-C) and nitrogen-containing ta-C films have been prepared using a magnetic-filtered plasma-deposition method in pure Ar, and Ar with N2 ambient, respectively. The structural and optical properties of these films have been studied using UV-visible optical absorption spectroscopy, Raman spectroscopy, and measurements of electrical conductivity in the temperature range from 300 to 500 K. The value of the optical band gap for the ta-C films deposited at suitable conditions were found to be larger than 3 eV. For nitrogen-containing ta-C films deposited at low partial pressure of nitrogen, the incorporation of a small amount of nitrogen will result in a slight drop in activation energy of conductivity and a decrease in band gap, which indicates that there are evidently both doping effect of nitrogen and graphitization of bonding. The study of surface morphology has been performed using atomic force microscopy (AFM), and results show that the surface roughness increases with the amount of nitrogen incorporated in ta-C films. The correlation between surface roughness and configuration of N atoms in ta-C network is also discussed.

The effect of preparation parameters on the particle size of silicon nanocrystallite produced by laser-induced chemical vapour deposition (LICVD) was studied. It is found that the particle size of nano-Si prepared by LICVD is related to preparation parameters. We obtained the optimum synthesis parameters for preparation of the right sized nano-Si powder produced by LICVD. The effect of different annealing treatments on the infrared (IR) absorption bands of the nanosized silicon was also investigated.

Tetrahedral amorphous carbon (ta-C) films have been prepared using a magnetic field filtered plasma stream system. The optical and microstructural properties of these films as a function of the substrate bias voltage, Vb, have been studied using optical absorption spectroscopy, Raman spectroscopy and atomic force microscopy. The results show that ta-C films with larger fraction of sp3 bonding were formed when the substrate bias voltage was in the range from −10 to −50V. The optical band gap is about 3.0 eV. The sp3 fraction in these films was estimated to be >80% by a fitting of the Raman spectra with a single skewed Lorentzian lineshape. The surface of such ta-C films was found to be smooth and uniform from the images of atomic force microscopy. The variations of the microstructural properties and surface morphology with Vb have been discussed in relation to evolution of the D and G Raman bands and root-mean-square surface roughness.

High dose carbon implantation into Si tip array was performed to synthesize SiC/Si heterostructure tip array. This was done using a high beam current density metal vapor vacuum arc ion source. Silicon tip arrays were prepared by anisotropic chemical etching. An implantation energy of 35 keV using a dose of 1.0×1018 ions/cm2 was performed. The array was subsequently annealed in argon ambient at 1200 °C, for various times to form the SiC surface layer. Scanning electron microscopy shows that the Si tips were sharp and uniformly arranged. X-ray photoelectron spectroscopy confirmed that a thin SiC surface layer had been formed. Results show that electron emission properties measured in ultrahigh vacuum depended on the sample treatment. A typical turn-on field was 15 V/μm when the emission current density reaches 1 μA/cm2. This compares with a turn-on field of about 35 V/μm for an unimplanted Si tip array.

X-ray photoelectron spectroscopy measurements of amorphous carbon nitride films have been performed. The samples were prepared by magnetic filtered plasma deposition, and cleaned by Ar+ ion sputtering before analysis to eliminate the surface contamination. The spectra include standard survey scans and high resolution scans of the photoelectron peaks of C, N, and O atoms. These spectra were collected using a monochromatic Mg Kα x-ray source operated at 300 W (20 mA, 15 kV). The survey scans were collected using an 80 eV pass energy, while high resolution scans were recorded using a 20 eV pass energy. By deconvolution of the XPS spectra, it was found that the XPS C 1s and N 1s signals could be deconvoluted into three and two Gaussian peaks, respectively. A plausible suggestion on the assignments of XPS peaks to C3N4, CNx, and ta-C phases was discussed. The relative abundance of CN bonds, calculated from the area of the respective C 1s Guassian peaks divided by the total area of the C 1s spectra, was determi...

Synthesis of undoped and doped tetrahedral amorphous carbon (ta-C) films has been achieved using magnetic field filtered plasma stream system in an ambient gas of pure Ar and Ar with N 2 , respectively. The optical and electrical properties of these films as a function of the substrate bias voltages ( V b ) or nitrogen partial pressures ( P N ) have been studied using UV-visible optical absorption spectroscopy, Fourier-transform infra-red spectroscopy (FTIR) and measurements of electrical conductivity. The results show that ta-C films with a high sp 3 fraction were formed when the V b was in the range of −10 to −50 V. The optical band gap of such ta-C films was found to be larger than 3 eV. The incorporation of nitrogen into the ta-C films deposited at low P N ( P N

Buried SiC layers were formed by dual-energy implantation of carbon into silicon at 40 and 65 keV to doses of 6 × 1017 and 1.2 × 1018 cm−2, respectively. Annealing was performed at temperatures from 600°C to 1200°C for various time intervals in nitrogen. The phase transformation characteristics in these SiC layers were studied using FTIR spectroscopy and a de-convolution scheme of the IR spectra into amorphous SiC and β-SiC components. The β-SiC fraction in the as-implanted samples was found to depend significantly on the order of the dual-energy implantation as a result of the IBIC effect. Further evolution of the relative amount of the various SiC phases upon annealing could well be described by the classical nucleation and growth theory using a two-dimensional growth model. The overall enthalpy of the transformation was determined to be 0.28 eV/atom.

A multi-layer structure of SiC/Si/SiO 2 was fabricated by successive deposition of SiC and Si using plasma-enhanced chemical vapor deposition and post-deposition thermal oxidation of the part as-deposited Si surface layer. The samples oxidized at 900 °C for various annealing times exhibit two strong photoluminescence peaks in the blue-light range, one is a stable PL peak at 433 nm and the other is an unstable PL peak at a range of 445–460 nm. A maximum PL intensity was obtained when oxidation time is 40 min over this oxidation time, the PL intensity decrease up to disappear with the increase of the oxidation time. Origin of the PL was discussed and a tight-binding theoretic calculation was used to study the relation of the excess Si defect and PL properties. Results show that the two PL peaks observed may be attributed to excess Si defect centers and SiC nanocrystalline with different size in SiC/Si/SiO 2 multi-layer structure.

Nitrogen-containing tetrahedral amorphous carbon films (ta-C) have been prepared using a magnetic field filtered plasma stream deposition method. The plasma stream was first formed by sputtering of a graphite target in nitrogen-argon atmospheres. The partial pressure of nitrogen, , was in the range 0-7 Pa at total pressure of deposition Pa. The optical and electrical properties of samples were studied using x-ray photoelectron spectroscopy (XPS), Fourier transform infrared absorption spectroscopy (FTIR), UV-visible optical absorption spectroscopy and measurements of electrical conductivity in the temperature range 300-500 K. The incorporation of small amounts of nitrogen will result in an increase in electrical conductivity, a slight drop of the band gap and an increase in band-tail absorption. These suggest that incorporation of a small amount of nitrogen into ta-C films will induce graphitization of bonding. For samples deposited at Pa, nitrogenation of films is very pronounced. The actual nitrogen content in films in terms of atomic percentage can be as much as 47%. The films have a wide band gap of 4.05 eV and an extremely low electrical conductivity. These suggest that a carbon nitride film is formed. The configurations of N atoms in the ta-C network are identified and discussed.

Carbon nitride films have been formed using a magnetic field filtered plasma stream deposition system. The electrical, optical and mechanical properties of these films deposited at different N2 partial pressures have been studied. Infrared spectra exhibit characteristic bands of carbon nitrogen bonds at 2200, 1500, 1350 cm−1, showing that the C and N atoms are chemically bonded in the films. X-ray photoelectron spectroscopy has been employed to measure the atomic ratio of N to C in the films. By deconvolution of the XPS spectra, it was identified that the films consist of three phases, namely, β-C3N4, CNx and ta-C. The relative fractions of these phases in the films were also determined. The optical band gap obtained from optical absorption spectra varies from 3.85 to 4.51 eV depending on the N2 partial pressure. The measured value of Vickers hardness Hv is between 4000 and 7000 kg/mm2. The effect of N2 partial pressure on the properties of these films is also discussed.

Ion beam synthesis of SiC layers was performed by carbon implantation into silicon with a metal vapor vacuum arc ion source under various implantation and annealing conditions. The infrared absorption spectra of these SiC layers were found to be composed of two or three components, one attributed to amorphous SiC and the other two to β-SiC. At a fixed dose, the total amount of SiC formed was found to increase linearly with the implant energy and at a fixed energy, to increase with a fractional power of the dose D, namely, Dγ with γ determined to be 0.41. It was also found that at a fixed dose there is a critical energy, and at a fixed energy there is a critical dose, at which the crystalline SiC fraction increases abruptly. These results were discussed in terms of the ion beam induced crystallization effect. Results on the effects of annealing to the total amount of SiC formed and the crystalline fraction are also presented and discussed.

Amorphous diamond (a-D) films have been formed by magnetic field filtered carbon ion deposition. The optical and electrical characteristics of these films as a function of the substrate bias voltage V b have been studied using optical absorption spectroscopy and electrical measurements. The results show that a-D films with high sp 3 fractions were formed when the substrate bias voltage V b was in the range −10 V to −50 V. The optical band gap of such a-D films was found to be larger than 3 eV. It is shown that optical absorption spectroscopy is a simple method to compare qualitatively the sp 3 fractions in carbon films. The mechanisms of transport in these films are also studied and discussed.

Gadolinium oxide (Gd2O3), which can be used as a T1-weighted magnetic resonance imaging (MRI) contrast agent, has attracted intense attention in recent years. In this paper, ligand-free monoclinic Gd2O3 nanocrystals of 7.1 nm in diameter are synthesized by a simple and green approach, namely microsecond laser ablation of a gadolinium (Gd) target in deionized water. These nanocrystals obtain high r1 relaxivity of 5.53 s(-1) mM(-1), and their low toxicity was demonstrated by the cell viability of S18 cells and apoptosis in RAW264.7 cells. In vitro and in vivo MR images show these particles to be good T1-weighted MRI contrast agents. Base on the experimental results and theoretical analysis, we suggest that the purity of the Gd2O3 contributes to its high r1 relaxivity value, while the low toxicity is due to its good crystallinity. These findings show that laser ablation in liquid (LAL) is a promising strategy to synthesize ligand-free monoclinic Gd2O3 nanocrystals for use as high efficient T1-weighted MRI contrast agents.

Double-sided DIBR can generate a perfect virtual view image. However, most of the data are the same in the two candidates. It is a waste cost. This paper proposed a simpler and more effective method to reduce the cost called forward and reverse wrapping DIBR (FR-DIBR). The FR-DIBR utilizes a main color image with associated depth map and an assistant color image. First, it wraps the main reference image to the virtual plane, and then reversely wraps the region of the disocclusion in the virtual view to the assistant reference image to get the lost information of the holes. The efficiency is improved by only wrapping one image and the disocclusion region. A depth map inpainting method called BBWF is also proposed. The experimental results show that the FR-DIBR can reduce the computation cost by 33 % and generate a clearer virtual image compared with the double-sided DIBR.

Image scaling is a very important technique and has been widely used in many image and video processing applications. To achieve the goal of low cost and real time, a novel scaling algorithm is proposed which consists of a bilinear interpolation and an adaptive sharpening filter. The proposed sharpening filter is added to perfect the blurring effects existing in traditional bilinear interpolation methods. Simultaneously, we also verify the scaling quality by taking into account the adaptive technology. Compared with the previous bilinear techniques, our method performs better in terms of both quantitative evaluation and visual quality.

Tetragonal BaTiO3 has been prepared from a reactive titanium source, tetrabutyl titanate, with barium acetate in alkaline aqueous solution at temperatures as low as 200–240 °C. Various methods, such as X-ray diffraction, differential scanning calorimetry and scanning electron microscopy have been used to investigate the effects of alkalinity, anions, reactivity of the titanium source and degrees of fill, on the particle sizes and morphologies of BaTiO3 generated hydrothermally. The most appropriate KOH concentration is about 1.0 mol l−1 in which BaTiO3 is the stablest phase in the BaO-TiO2 system. Compared with chloride and nitrate ions, the acetate ion accelerates the formation of large-grained particles of BaTiO3 more prominently. A more reactive titanium source and a higher fill can promote the formation of tetragonal BaTiO3.

Based on the analysis of conventional deinterlacing methods, a new motion adaptive deinterlacing method is proposed. In this paper, we improve three aspects of the conventional motion adaptive method. Firstly, we add a FIR filter to the motion detection part, which not only avoids the wrong detecting of moving objects but also reduces the noises effectively. Secondly, according to the fact, that human eyes are less sensitive to lighter or darker area than gray area, a threshold adaptive method is introduced, which enhanced the subjective quality of deinterlacing. Thirdly, we adopted different interpolation methods for different pixels, which improved the deinterlacing quality of motionless videos. The simulation results show that our proposed deinterlacing method can achieve higher PSNR (peak signal noise ratio) than that of previous studies and can also attain better quality of subjective view.

We report fabrication of random nanometer-scale radial p-n junction solar cells (SCs). Nanoholes were fabricated on the Si wafer by combining silver film annealing and metal catalyzed electrochemical etching (MECC) of the material. The dimension of the holes can be adjusted by varying the annealing conditions and the thickness of the Ag film. Systematic investigations on the effects of the nanohole size and the doping conditions on the cell efficiency were performed.

Stacks of multilayered rutile TiO(2) nanoflowers can grow on a titanium film through a simple acid vapour oxidation (AVO) method. The growth of this interesting hierarchical architecture is due to the formation of rutile {101} twinned structures and a subtle mismatching between the lattice spacings of the substrate and product.

Bit Plane Coding (BPC) is an important component of the EBCOT block in JPEG2000 encoder. This paper introduced new algorithm for neighboring significance contribution and Run Length Coding (RLC). The paper also presented a fast word level sequential scheme and parallel architecture for bit plane coding. Bit plane coding adopted by EBCOT is mainly divided into three stages: significance generation, coding pass prediction and context formation, which work in parallel and pipelined. The proposed architecture simplifies control procedure and operates at a higher processing speed (up to 164MHz in Xilinx Virtex 4 FPGA).

An high-performance implementation of 2-D lifting-based Discrete Wavelet Transform (DWT) in JPEG2000 applications is designed with low memory and high pipeline architecture. The architecture consists of a row processor module, a column processor module and two memory modules. we present two new row/column processor architecture and memory architecture, one of which includes 7 dual port rams. The For the N*N tile image, only 4N temporal memory are required for 5/3 filter. Symmetric extension is used at the boundaries. Two outputs are generated every cycle. Finally, the proposed architecture was implemented in behavioral verilog-HDL with FPGA (virtex2), the result of which occupied about 400 slices, and was operated in about 120MHz.

A difference method for detection of QRS is proposed in this paper. By calculating the difference function of the Electrocardiogram (ECG), the method can eliminate or weaken the impact of the P wave, T wave and other interference signals onto the detection of QRS. It can solve the problem of low detection accuracy yielded by the traditional method, and can solve the problem of heavily loaded computation caused by the complicated algorithm of the wavelet method. Experiments using data from the MIT-BIH arrhythmia database illustrate that this method has good adaptability for various ill-conditioned ECG waves. This method has found clinical applications in the '12 lead ECG system' developed by the authors. The detection accuracy rate is higher than 99%.

A remarkably low turn-on field of about 1 V/μm has been observed in electron field emission from planar SiC/Si heterostructures formed by high dose C implantation into Si using a metal vapor vacuum arc ion source. An implant energy of 35 keV was used to a dose of 1.0×1018 ions/cm2 with subsequent annealing in nitrogen at 1200 °C for 2 h. X-ray photoelectron spectroscopy showed that a thin surface stoichiometric SiC layer, with a thickness of about 150 nm, had been formed. Atomic force microscopy showed that there are densely distributed small protrusions formed on the surface. The formation of a thin surface stoichiometric SiC layer and the formation of densely distributed small protrusions on the surface are believed to be the two factors responsible for the efficient electron field emission.

Planar SiC/Si heterostructures were formed by high dose carbon implantation using a metal vapor vacuum arc ion source. The variations of the field emission properties with the implant dose and annealing conditions were studied. A remarkably low turn-on field of 1 V//spl mu/m was observed from a sample implanted at 35 keV to a dose of 1.0/spl times/10/sup 18/ cm/sup -2/ with subsequent annealing in nitrogen at 1200/spl deg/C for 2 h. The chemical composition depth profiles were determined from X-ray photoelectron spectroscopy and the surface morphology was observed by atomic force microscopy. The formation of a thin surface stoichiometric SiC layer and the formation of densely distributed small protrusions on the surface are believed to be the two factors responsible for the efficient electron field emission.

Planar SiC/Si heterostructures were formed by high dose carbon implantation using a metal vapor vacuum arc ion source. The variations of the field emission properties with the implant dose and annealing conditions were studied. A remarkably low turn-on field of IV/μm was observed from a sample implanted at 35 keV to a dose of 1.0×1018 cm−2 with subsequent annealing in nitrogen at 1200°C for 2h. The chemical composition depth profiles were determined from x-ray photoelectron spectroscopy and the surface morphology was observed by atomic force microscopy. The formation of a thin surface stoichiometric SiC layer and the formation of densely distributed small protrusions on the surface are believed to be the two factors responsible for the efficient electron field emission.

High dose carbon implantation into Si with a MEVVA ion source was performed to form SiC/Si heterostructures. By deconvoluting the FTIR spectra into gaussian components corresponding to amorphous SiC and crystalline SiC phases, the implant energy, dose and annealing temperature dependence of phase formation properties of SiC in these structures were studied. It was found that there are critical energies and critical doses at which there are abrupt increases in the fraction of the crystalline SiC phase formed. This was discussed in terms of the ion beam induced crystallization effect. Results of electron field emission measurements showed that a remarkably low turn-on field of about IV//spl mu/m could be achieved from these planar SiC/Si structures prepared with appropriate implant and annealing conditions.

Buried SiC layers were synthesized by carbon implantation into silicon with a metal vapor vacuum arc ion source under various implantation and annealing conditions. The infrared absorption spectra of these samples were deconvoluted into two or three gaussian components depending on the preparation conditions. One component peaked at around 700 cm-1was assigned to amorphous SiC (a-SiC). The other two components, both peaked at 795 cm-1 but with different values of full width at half maximum (FWHM), were attributed to β-SiC. The one with a larger (smaller) FWHM corresponds to β-SiC of smaller (larger) grains. With this deconvolution scheme, the fraction of various SiC phases in these samples were determined. It was found that for the as-implanted samples there are critical energies and doses at which the crystalline SiC fraction increases abruptly. This was attributed to the ion beam induced crystallization (IBIC) effect. It was also shown that the IBIC effect leads to strong dependence of the β-SiC fraction on the order of implantation for samples synthesized by double-energy implantation. Analysis of the evolution of the β-SiC fraction with annealing time indicated that the crystallization process in these SiC layers could well be described by the classical random nucleation and growth theory.

Carbon nitride films prepared by magnetic filtered plasma deposition were characterized using Fourier transform infrared (FTIR) absorption and X-ray photoelectron spectroscopy (XPS). Characteristic bands corresponding to C-N, C=N, C=N, and C=C bonds were observed in FTIR spectra. It was found that the XPS C 1s and N 1s signals could be deconvoluted into three and two gaussian peaks, respectively. A plausible suggestion on the assignments of the XPS peaks to C3N4, CNx and ta-C phases was discussed. The relative abundance of the various CN bonds, the relative abundance of the various bonding components from XPS results, and their dependence on the nitrogen partial pressure PN during deposition were analyzed. Assuming the assignments of the XPS peaks to the various phases, the XPS results suggested that there would be an optimal PN that would favor the growth of the C3N4 phase. The electrical conductivity, the optical band gap and the Vickers hardness of these films were measured and the effects of PN on these properties were studied.

Ultra-small gadolinium oxide (Gd2O3) can be used as T1-weighted Magnetic Resonance Imaging (MRI) contrast agent own to its high longitudinal relaxivity (r1) and has attracted intensive attention in these years. In this paper, ultra-small Gd2O3 nanoparticles of 3.8 nm in diameter have been successfully synthesized by a microsecond laser ablating a gadolinium (Gd) target in diethylene glycol (DEG). The growth inhibition effect induced by the large viscosity of DEG makes it possible to synthesize ultra-small Gd2O3 by laser ablation in DEG. The r1 value and T1-weighted MR images are measured by a 3.0 T MRI spectroscope. The results show these nanoparticles with a high r1 value of 9.76 s−1 mM−1 to be good MRI contrast agents. We propose an explanation for the high r1 value of ultra-small Gd2O3 by considering the decreasing factor (surface to volume ratio of the nanoparticles, S/V) and the increasing factor (water hydration number of the Gd3+ on Gd2O3 surface, q), which offer a new look into the relaxivity studies of MRI contrast agents. Our research provides a new approach to preparing ultra-small Gd2O3 of high r1 value by laser ablation in DEG and develops the understanding of high relaxivity of ultra-small Gd2O3 MRI contrast agents.

Ion beam synthesis of SiC/Si heterostructures was performed by MIEVVA (metal vapor vacuum arc) implantation under various implantation and annealing conditions. The implanted SiC/Si heterostructures were characterized by various techniques. Carbon redistribution in overstoichiometrically implanted samples during annealing to form a stoichiometric SiC layer has been observed for the first time. The FTIR spectra were found to be composed of two components, one attributed to amorphous SiC and the other to ß-SiC. It was also found that there are critical dose and critical energy at which the crystalline fraction increases abruptly. Other results on electrical and optical characterization are also presented and discussed.

In this paper, the adsorption behavior of plasma proteins on the surface of ZnO thin films prepared by radio frequency (RF) sputtering under different sputtering powers was studied. The microstructures and surface properties of the ZnO thin films were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible optical absorption spectroscopy and contact angle techniques. The results show that the ZnO thin films have better orientation of the (0 0 2) peak with increasing RF power, especially at around 160 W, and the optical band gap of the ZnO films varies from 3.2 to 3.4 eV. The contact angle test carried out by the sessile drop technique denoted a hydrophobic surface of the ZnO films, and the surface energy and adhesive work of the ZnO thin films decreased with increasing sputtering power. The amounts of human fibrinogen (HFG) and human serum albumin (HSA) adsorbing on the ZnO films and reference samples were determined by using enzyme-linked immunosorbent assay (ELISA). The results show that fewer plasma proteins and a smaller HFG/HSA ratio adsorb on the ZnO thin films' surface.