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The temperature dependence of the ferroelectric and dielectric properties of PbZr0.5Ti0.5O3 thin films deposited on LaNiO3-coated SrTiO3 substrate was investigated. The results showed that both the saturation polarization and remanent polarization increased with decreasing temperature from 300 to ∼50 K, and decreased as the temperature continued to decrease below 40 K. The capacitance of the PbZr0.5Ti0.5O3 ferroelectric thin film capacitor as a function of small ac field and temperature was measured, and the data were processed using Rayleigh law. It was demonstrated that both the reversible and irreversible contributions to the dielectric constant decreased with decreasing temperature; however, they showed an increase when the temperature dropped below 50 K. The anomalous behavior of the temperature dependence may be attributed to a phase transition in the PbZr0.5Ti0.5O3 thin film in the vicinity of 50 K.

From the capacitance–voltage dependence of Pt/PbZr0.5Ti0.5O3/Pt capacitors, we mathematically separated the capacitance into two parts corresponding to two regions of the samples, the uniform electric-field region and the nonuniform region. They are correlated with the bulk ferroelectric film region and the Pt/PbZr0.5Ti0.5O3 Schottky barrier interface region, respectively. The calculations based on the in-series capacitor model show a slight decrease of dielectric permitivity for the fatigued bulk films. By assuming a much smaller dielectric permitivity of the interface region than that of bulk films, it was found that the interface capacitance decreased remarkably compared with that of the bulk ferroelectric film after fatigue. This decrease was attributed to the lowering of ferroelectricity in the interface layer, which suggests that the fatigue is mainly an interface state controlled process. The asymmetricity in the interface capacitance–voltage curve is attributed to the different defect concentratio...

Using infrared spectroscopic ellipsometry, the optical constants of LaNiO3 thin films on Pt(111)–Ti–SiO2–Si substrates are obtained in the 2.5–12.6 μm range, in which the infrared optical constants decrease when the annealing temperature increases from 600 to 650 °C. At the same time, the infrared optical properties of PbZrχTi1−χO3(PZT) thin films with χ=0.3 and 0.5 on LaNiO3–Pt–Ti–SiO2–Si substrates are simultaneously studied with respect to annealing temperatures. The infrared optical properties are associated closely with the grain size and crystallographic orientation of the films induced by annealing temperature, combined by the particular substrate. For the Ni–PZT–LaNiO3–Pt multilayer heterostructures, the infrared absorptance better than 99% can be achieved for PZT pyroelectric thin film infrared microsensors.

The stationary properties of high- T c ramp type Josephson junctions with a graded Y 1-x Pr x Ba 2 Cu 3 O y barrier have been studied. In such a structure the composition of the Y 1-x Pr x Ba 2 Cu 3 O y barrier is continuely changed as x increasing from 0 to 1 at one side of the PrBCO barrier and vice verse at the other side. The critical current of these junctions showed a nearly linear dependence on the temperature. The experimental results were discussed in comparing with theoretical models.

(Ba , Sr)TiO 3 (BST) thin films were deposited on the conducting perovskite LaNiO 3 electrode by radio-frequency (rf) magnetron sputtering technique. To investigate the cr ystalline of BST films, the substrate temperatures ( T d ) in the range of 100 0 C-700 C were applied. The transition from amorphous phase to polycrystalline phase for the films occurred at low growth temperature 300 0 C. When the growth temperature approached 500C, highly (h00)-oriented films were obtained. The relative dielectric constant ( 0 r ) increased rapidly with enhancing grow th temperature because of improved crystallinity, and showed sl owly increase above 500 0 C. In addition, the capacitance-voltage characteristics were studied with various growth temperatures. The tunability increased largely with good crystallinity. This can be attributed to increased dielectric constants. Keywords: (Ba , Sr)TiO 3 thin films, LaNiO 3 electrode 1. INTRODUCTION (Ba,Sr)TiO 3 (BST) thin films have attracted great interest for prac tical uses as a capacitor diel ectric for future generation high density dynamic random access memo ries (DRAMs), tunable microwave device [1-2]. For these devices, it was required that BST films have high dielectric constant, high dielectric nonlinearity, low dielectric loss, and low leakage current density. Usually, the dielectric and electricial properties could be affected by the film characteristics, including stoichiometry, crystallinity, microstructure, and crystallographic orientation. Therefore, it was important to control the growth conditions and adjust the orientation of the films with regard to the specific device application. For this purpose, the metallic oxide IrO

SrTiO 3 (STO) thin films were grown on Si(100) substrates by RF magnetron sputtering. The substrate temperature was found to be a crucial parameter to obtain the highly (h00) oriented growth. At the substrate temperature of 700 °C, STO thin films with the (h00)-orientation parameter (α h00 ) of more than 93% were realized. Using vitreous silica as the substrate, the optical properties of STO thin film prepared at 700 °C were investigated by transmittance measurements. The fitting method was used to calculate the refractive index and the film thickness from the transparent region of the transmittance spectra. The dispersion of the refractive index was studied by considering a single electronic oscillator model. According to Tauc's law, the band gap of the film was found to be about 3.62 eV.

Using Landau-Devonshire(LD)-type phenomenological model, we investigate the phase diagrams and in-plane anisotropic misfit strains of single-domain single-crystal (110) Ba 0.6 Sr 0.4 TiO 3 film epitaxially deposited on (001) NdGaO 3 substrate. Investigation indicates that film thickness plays a crucial role on formation of in-plane anisotropic misfit strains and stable phases. As is consistent with results of experiment that anisotropic strains have greatly changes with increase of film thickness. The anisotropic strains induce tetragonal phases which only contain in-plane spontaneous polarization component. These phases do not exist in BST films of the same composition under isotropic strains. Moreover, calculation manifests that anisotropic in-plane misfit strains are almost completely relaxed when film thickness is larger than 600nm, which has been reported in experiment.

In situ observation of the bainite carbide precipitation processes in 40CrMnSiMoV steel by means of high-temperature transmission electron microscopy (TEM) is conducted. It is evident that carbides can precipitate either in bainitic ferrite or from austenite when carbide-free bainite (meta-bainite) obtained by isothermal transformation is tempered at higher temperatures. In view of the quantity of carbides precipitated from ferrite in combination with the result of an X-ray diffraction analysis of the bainitic ferrite carbon content, it can be concluded that bainitic ferrite growth involves supersaturation of carbon content to some degree.

Telomerase is an important biomarker in cancer cells. It is active in germline cells, most of cancer tissues and cell lines, but not in most somatic tissues. Telomerase is composed of two components, and while hTER is present in normal and tumor cells, expression of hTERT appears to be highly regulated and correlates with telomerase activity. In order to detect the telomerase enzyme and hTERT protein, anti-hTERT polyclonal antibodies were produced in this study. A segment of hTERT cDNA was amplified by RT-PCR and cloned into the multi-cloning site of the GST gene fusion vector pGEX-5X-3. After the recombinant plasmid was expressed in E. coli BL21, the fusion protein was purified for immunization. Extracts from several cultured cells were analyzed by Western blot, and the results indicated that telomerase enzyme and hTERT protein could be specifically detected by this anti-hTERT antibod'. Thus, a simple and effective method was primarily established for the immunodetection of telomerase enzyme and hTERT protein.

Recent studies have shown that vitamin D receptor (VDR) gene polymorphism had regulatory effects on bone mineral density (BMD) and bone turnover. The VDR gene has also been indicated as a candidate gene for the susceptibility of osteoporosis. However, it is unclear whether VDR genotypes could be associated with alveolar bone loss of patients with periodontitis, or whether vitamin D receptor gene could be a candidate gene for susceptibility to periodontitis. The purpose of this study was to answer these two questions.Twenty-four cases of adult periodontitis (AP), 37 cases of early onset periodontitis (EOP) and 39 healthy controls were recruited for the study. Individual samples of venous blood and DNA were obtained from each subject. Genotypes of the TaqI VDR gene were determined by PCR and TaqI restriction endonuclease digestion.One out of 24 AP patients, nine out of 37 EOP patients and two out of 39 healthy controls were detected with Tt genotype, while the rest had the TT genotype. The detected frequency of Tt genotype was significantly higher in EOP patients (24.3%) than in AP patients (4.2%) and healthy controls (5.1%). The frequency of t allele was also significantly higher in EOP patients. There was no statistical difference in the distribution of TaqI VDR genotypes between AP patients and healthy controls. The study suggests that Tt genotype might be a risk indicator for the susceptibility to EOP. Carriage of the allele (t) of the TaqI VDR gene may increase the risk of developing EOP.

Multiple dielectric responses are comparatively investigated in the pure and nitrogen-ion-implanted (Ba, Sr)TiO3 (BST) films. Larger diffusive degree of phase transition and more relaxor-like features than those of pure BST films are observed in implanted ones, where the long-range-dipolar-correlated-orders were further segregated into local polar orders after the implantation. Moreover, the implanted films possess a transition from local reorientations of groups of dipoles induced nearly constant-loss (NCL) type to oxygen vacancies (Vo) hopping type conduction at high temperature. Whereas, pure films behave as NCL type conduction along with a dielectric relaxation, which arises from the motions of defect complexes Vo 2+–Ti3+.

The Schizosaccharmyces pombe pac-1 gene product is a kind of dsRNA dependent ribonuclease, which has potential to degrade the dsRNA viral genome, the replication form of ssRNA viral genome and viroid genome. Therefore, to introduce the pac-1 gene into plants conferring them resistance to viruses is a new method of establishing the anti-virus transgenic plant. The pac-1 gene from the S. pmobe genome DNA isolated from China was cloned by means of PCR amplification. The pac-1 gene was inserted into the cloning vector pGEM-7Zf(+) by using restriction endonuclease Kpn I/BamHI. Sequencing analysis shows that it is a complete gene with 1095 necleotides. Compared to the reported pac-1 gene, its homology is significant, but with 5 nucleotides differences, leading to only one amino acid difference. Pac-1 gene was inserted into the prodaryotic expression vector pET-21(a) by using the restriction endonuclase Nde I/BamHI. It was induced by the IPTG in E. coli BL21 harbouring the recombinant vector pET-pac-1. The pac-1 gene product is analyzed by the SDS-PAGE. The result shows the product of pac-1 gene exists in the supernatant part as soluble form and in the precipitant part as inclusion bodies after the cells were lysed by ultrasonic wave. The supernatant was applied to detect the enzyme activity of pac-1 gene product. We concluded that pac-1 gene has the biological activity of degrading the CMV-dsRNA.

The polarization switching behavior in poly(vinylidene fluoride-trifluoroethylene) thin films is studied by using a pulse transient current method. The dependence of the domain switching current on the coercive electric field was investigated. The charging current around the coercive field was found to be limited by domain switching instead of the series resistor in the measurement circuit because of the slow polarization switching in the films. The domain-switching process was explained by a creep model wherein the two-dimension domain walls motion in the transverse direction dominates the polarization switching process.

The pharmacokinetics and pharmacodynamics of changrolin (CRL) were studied in 7 dogs with arrhythmia induced by coronary artery ligature. The ECG and the percentage of reduction ratio of ventricular premature were used to evaluate the effect of CRL, and an HPLC method was used to determine the serum drug concentration. A pharmacokinetic program was used to fit concentration-time (C-T) data and a combined pharmacokinetic-pharmacodynamic model was used to analyze effect-time (E-T) data in individual dogs. After infusion with CRL 83.33 micrograms.kg-1.min-1 for 60 min, it was found that K10, T1/2, Vd, Cl and Ce were 0.0087 min-1, 78.03 min, 40.55 ml.kg-1, 0.42 ml.kg-1.min-1, and 2.01 micrograms.ml-1, respectively.

Direct laser cladding of Al-Sn alloy on mild steel produces continuous brittle intermetallic FexAly layers at the interface resulting in weak bonding of the clad and the substrate. To overcome this problem, both Ni and Al were investigated as intermediate coatings. Although a Ni coating with a thickness of 70 μm was successful in eliminating the formation of continuous Al-Fe intermetallic compounds, the bonding at the Al alloy-Ni interface was not strong enough to survive a bending test. A pure Al coating was found to be a better barrier layer.In both cases the optimisation of processing parameters for Al alloy cladding was realised via microstructural screening and mechanical property testing including Vickers hardness, preliminary wearing and bending tests. Operating windows were established in terms of low dilution, freedom from cracks and porosity, coating-substrate bonding and chemical homogeneity. The results of a comparative study indicated that the laser clad layers showed superior wear resistance to the conventional alloy. The morphology of the rapid solidification clad was investigated by means of optical and electron microscopy. The alloying element distribution was analysed using electron probe microanalysis (EPMA). A simplified model based on the calculation of the clad/substrate interface temperature was developed to provide a guideline for choosing the processing parameters of successful cladding.Direct laser cladding of Al-Sn alloy on mild steel produces continuous brittle intermetallic FexAly layers at the interface resulting in weak bonding of the clad and the substrate. To overcome this problem, both Ni and Al were investigated as intermediate coatings. Although a Ni coating with a thickness of 70 μm was successful in eliminating the formation of continuous Al-Fe intermetallic compounds, the bonding at the Al alloy-Ni interface was not strong enough to survive a bending test. A pure Al coating was found to be a better barrier layer.In both cases the optimisation of processing parameters for Al alloy cladding was realised via microstructural screening and mechanical property testing including Vickers hardness, preliminary wearing and bending tests. Operating windows were established in terms of low dilution, freedom from cracks and porosity, coating-substrate bonding and chemical homogeneity. The results of a comparative study indicated that the laser clad layers showed superior wear resistance...

The poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene) terpolymer (56.2/36.3/7.5, mol %) films from 1.6 to 10 nm in thickness were prepared by the Langmuir–Blodgett method. The dielectric and ferroelectric properties of the terpolymer films were investigated. The phase transition of the films of less 3.2 nm in thickness exhibits a ferroelectric-like nature, which is inconsistent with the bulk terpolymers. The peak of the permittivity is at ∼360 K, which is much higher than the thick terpolymer films and it is independent on frequency. Both polarization-electric field and capacitance-voltage curves show a ferroelectric-like characteristic, which is confirmed by piezoresponse force microscopy, suggesting the presence of all-trans molecular conformation.

We report an unusual dielectric relaxation phenomenon associated with dipolar defect complexes Ti3+-(Vo2−)•• observed in the PbZr0.38Ti0.62O3 multilayers. The dielectric loss aroused by the polarization of defect dipoles varies with time under ac electric fields, and its change can be controlled by an applied dc bias. This abnormally dynamic behavior of dielectric loss can be interpreted by the formation and dissociation of dipolar defect pairs Ti3+-(Vo2−)•• by injection of charged carriers. These investigations may be beneficial to getting further insight into the defect dynamics and the mechanism of ferroelectric polarization fatigue and restoration in ferroelectric materials.

The 70%Pb(Mg1∕3,Nb2∕3)O3–30%PbTiO3 (PMNT) films have been fabricated on LaNiO3 (LNO) coated silicon substrate. The conductive LNO films act as a seed layer for the growth of PMNT films, which depresses the formation of pyrochlore phase and induces the high (100) preferred orientation of perovskite PMNT films. Compared with the PMNT films grown on platinum bottom electrode, the ferroelectric properties of PMNT films grown on LNO are enhanced. The frequency dependence of complex permittivity from PMNT films on LNO is the conjunct result of polarization relaxation and movement of oxygen vacancy, which can be fitted by the function containing Debye and universal dielectric response models, respectively.

Based on phase separation, quasiperiodic PbZr0.4 Ti0.6O3 (PZT) multilayers with alternating PZT and porous-PZT layers were fabricated by using a single precursor, and the ferroelectric and dielectric behaviours of the PZT multilayers were investigated. The PZT multilayers have an averaged remanent polarization of 42.3 ?C?cm?2 and an average coercive field of 43?kV?cm?1. Two distinct dielectric relaxation phenomena were observed in the frequency range from 100?Hz to 1?MHz: the one at lower frequency is attributed to space charge polarization, while the one at higher frequency, with an activation energy of 0.49?eV, is expected to be associated with dipolar defect complexes related to oxygen vacancies.

BiFeO3∕Pb(Zr0.5,Ti0.5)O3 (BFO/PZT) multilayer films have been grown on platinum-coated silicon substrate by chemical solution deposition. The remnant polarization is about 12μC∕cm2, which is much bigger than most of pure BFO thin films. P-E measurement shows that there are more obstacles affecting the motion of the domain wall in the multilayer films than those in the pure PZT films. This conclusion is also confirmed by measuring the dependence of capacitance with ac field under subswitching field. The frequency dependence of dielectric loss indicates that the dielectric loss (tanδ) of the multilayer is smaller than that of the PZT thin films at high frequency. Magnetic measurement indicates that the multilayer films are antiferromagnetic.

92%Pb(Mg1∕3Nb2∕3)O3–8%PbTiO3 (PMNT) thin films have been prepared on Pt∕Ti∕SiO2∕Si substrate with a LaNiO3 (LNO) buffer layer and on sapphire substrate by a chemical solution deposition method, respectively. X-ray diffraction analysis shows that the PMNT thin films on Pt∕Ti∕SiO2∕Si substrate are polycrystalline with (110)-preferential orientation. Pt∕PMNT∕Pt capacitors have been fabricated and show a ferroelectric character with a spontaneous polarization (Ps) of 25.2μC∕cm2 and a remanent polarization (Pr) of 6.56μC∕cm2. The dielectric constant (er) and the dissipation factor (tanδ) at 1 kHz are 680 and 0.014, respectively. The band-gap energy of the PMNT thin films on the sapphire substrate was found to be about 4.03 eV by the optical transmission spectra measurement. The optical constants (n, k) of the PMNT thin films in the wavelength range of 2.5–12.6 μm were obtained by infrared spectroscopic ellipsometry measurement.

A method for thin-film fabrication employing high oxygen-pressure processing (HOPP) was developed. With this method, the highly (100) oriented Pb(ZrxTi1−x)O3 (PZT) thin film was fabricated at temperature as low as 400°C. HOPP is compatible to the ferroelectric PZT film integration with a readout integrated circuit. The sol-gel-derived PZT 50∕50 thin film showed a well-saturated hysteresis loop at an applied electric field of 367kV∕cm with Pr and Ec of 45μC∕cm2 and 121kV∕cm, respectively. Large electric leakage was attributed to remnant organic components, which was demonstrated by sputtered organic-free PZT films. The optimized Pr and Ec are of 26μC∕cm2 and 93kV∕cm under an applied electric field of 400kV∕cm.