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International audience; Brown and brown-like adipocytes (BBAs) control thermogenesis and are detected in adult humans. They express UCP1, which transforms energy into heat. They appear as promising cells to fight obesity. Deciphering the molecular mechanisms leading to the browning of human white adipocytes or the whitening of BBAs represents a goal to properly and safely control the pathways involved in these processes. Here, we analyzed how drugs endowed with therapeutic potential affect the differentiation of human adipose progenitor-cells into BBAs and/or their phenotype. We showed that HIV-protease inhibitors (PI) reduced UCP1 expression in BBAs modifying their metabolic profile and the mitochondria functionality. Lopinavir (LPV) was more potent than darunavir (DRV), a last PI generation. PPARγ and PGC-1α were decreased in a PI or cell-specific manner, thus altering UCP1's constitutive expression. In addition, LPV altered p38 MAPK phosphorylation, blunting then the β-adrenergic responses. In contrast, low doses of resveratrol stimulated the activatable expression of UCP1 in a p38 MAPK-dependent manner and counteracted the LPV induced loss of UCP1. This effect was independent of the resveratrol-induced sirtuin-1 expression. Altogether our results uncover how drugs impact crucial components of the networks regulating the expression of the thermogenic signature. They provide important information to control the relevant pathways involved in energy expenditure.

When used in tissue engineering, polymer nanofibers with magnetic and electrical functionality could promote the growth of tissues and cells by applying magnetic and electric stimulation. Short nanofibers with these properties, which have a high specific surface area and can be arranged through magnetic induction, have potential applications in the fields of materials and biomedical engineering. In this study, poly(lactic-co-glycolic acid) (PLGA) nanofibers with nano-Fe₃O₄ particles were subjected to electrostatic spinning to obtain superparamagnetic Fe₃O₄/PLGA nanofibers. After being processed in a homogenizer, graphene/Fe₃O₄/PLGA short nanofibers with a length of 11.90±2.03 μm and a diameter of 256.5±13.7 nm were prepared by in situ deposition. The effects of the PLGA concentration and graphene concentration on the morphology, size and conductivity of short fibers were studied by scanning electron microscopy (SEM) and conductivity testing. The chemical composition of the short fibers was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The magnetic properties of the short fibers were characterized by using a vibrating sample magnetometer (VSM). Superparamagnetic and conductive PLGA nanofibers with a conductivity of 9.34×10-2 S/m were obtained for further applications.

Studying the structure and the dynamics of kinetochores and centromeres is important in understanding chromosomal instability (CIN) and cancer progression. How the chromosomal location and function of a centromere (i.e., centromere identity) are determined and participate in accurate chromosome segregation is a fundamental question. CENP-A is proposed to be the non-DNA indicator (epigenetic mark) of centromere identity, and CENP-A ubiquitylation is required for CENP-A deposition at the centromere, inherited through dimerization between cell division, and indispensable to cell viability. Here we describe mass spectrometry analysis to identify ubiquitylation of EYFP-CENP-A K124R mutant suggesting that ubiquitylation at a different lysine is induced because of the EYFP tagging in the CENP-A K124R mutant protein. Lysine 306 (K306) ubiquitylation in EYFP-CENP-A K124R was successfully identified, which corresponds to lysine 56 (K56) in CENP-A through mass spectrometry analysis. A caveat is discussed in the use of GFP/EYFP or the tagging of high molecular weight protein as a tool to analyze the function of a protein. Current technical limit is also discussed for the detection of ubiquitylated bands, identification of site-specific ubiquitylation(s), and visualization of ubiquitylation in living cells or a specific single cell during the whole cell cycle. The method of mass spectrometry analysis presented here can be applied to human CENP-A protein with different tags and other centromere-kinetochore proteins. These combinatory methods consisting of several assays/analyses could be recommended for researchers who are interested in identifying functional roles of ubiquitylation.

Summary Many oil and gas resources in deep–sea environments worldwide are often located in high–temperature/high–pressure (HT/HP) and low–permeability reservoirs. The reservoir–pressure coefficient usually exceeds 1.6, with formation temperature greater than 180°C. Challenges are faced for well drilling and completion in these HT/HP reservoirs. A solid–free well–completion fluid with safety density greater than 1.8 g/cm3 and excellent thermal endurance is strongly needed in the industry. Because of high cost and/or corrosion and toxicity problems, the application of available solid–free well–completion fluids such as cesium formate brines, bromine brines, and zinc brines is limited in some cases. In this paper, novel potassium–based phosphate well–completion fluids were developed. Results show that the fluid can reach the maximum density of 1.815 g/cm3 at room temperature, which makes a breakthrough on the density limit of normal potassium–based phosphate brine. The corrosion rate of N80 steel after the interaction with the target phosphate brine at a high temperature of 180°C is approximately 0.1853 mm/a, and the regained–permeability recovery of the treated sand core can reach up to 86.51%. Scanning–electron–microscope (SEM) pictures also support the corrosion–evaluation results. The phosphate brine shows favorable compatibility with the formation water. The biological toxicity–determination result reveals that it is only slightly toxic and is environmentally acceptable. In addition, phosphate brine is highly effective in inhibiting the performance of clay minerals. The cost of phosphate brine is approximately 44 to 66% less than that of conventional cesium formate, bromine brine, and zinc brine. This study suggests that the phosphate brine can serve as an alternative high–density solid–free well–completion fluid during well drilling and completion in HT/HP reservoirs.

A strategy has been applied to chloramphenicol (CAP) detection with chemiluminescence immunoassays (CLIA) based on cheap functionalized Fe3 O4 @SiO2 magnetic nanoparticles (Fe-MNPs). The strategy that bovine serum albumin (BSA) was immobilized on cheap functionalized Fe-MNPs and that the CAP molecules were then immobilized on BSA, avoided the long process of dialysis for preparation of the BSA-CAP conjugates. The samples were detected for both methods that utilized two different kinds of functionalized Fe-MNPs (amine-functionalized Fe3 O4 @SiO2 and carboxylic acid-functionalized Fe3 O4 @SiO2 ). The sensitivities and limits of detection (LODs) of the two methods were obtained and compared based on inhibition curves. The 50% inhibition concentrations (IC50 ) values of the two methods were about 0.024 ng ml-1 and 0.046 ng ml-1 respectively and LODs were approximately 0.0002 ng ml-1 and 0.001 ng ml-1 respectively. These methods were much more sensitive than that of any traditional enzyme-linked immunosorbent assay (ELISA) previously reported. Therefore, such chemiluminescence methods could be easily adapted for small molecule detection in a variety of foods using Fe-MNPs.

The exploration of ultra-high pressure reservoirs is becoming more and more common due to the increasing demand of fossil fuels. It is anticipated that well drilling and completion in ultra-high pressure reservoirs will be the main exploration work in the future. The highest density of cesium formate brine is only 2.42 g/cm3, which cannot be served as the well completion fluid in ultra-high pressure reservoirs. The development of a higher density solid-free completion fluid has become a increasing demand as well as big challenge for ultra-high pressure reservoir exploration. In this paper, heteropolysate solid free brine was first applied to the field of completion fluid, and its density can reach at 2.8 g/cm3 or higher, which makes a breakthrough on the density limit of existing solid-free brines. The physical performance of heteropolysate brine is stable at 1–180 °C, and the mechanism of its dissolution and stability is illustrated. The corrosion rate of fluid is 0.0899 mm/a at 180 °C and the regained permeability recovery for tight cores is about 80%. The heteropolysate brine has the good compatability with formation water and oil and the biotoxicity evaluation shows that the brine is only slightly toxic (EC50 belongs to the range of 1000–25000 mg/L). The cost of heteropolysate brine is generally lower than that of cesium formate brines and it is recyclable. The heteropolysate brine in this study is applicable to both oil and gas reservoir and has the potential to be served as the well completion fluid for the ultra-high pressure reservoir development.

It has been reported previously that polyvinyl acetate (PVAc) additive can increase obviously single layer thickness of PbTiO3 (PT) thin films, and in turn result in less repeated coating cycles. In this paper, the influence of PVAc on the morphology and property of the PT thin films in different thermal treatment process, the conventional furnace annealing (CFA) process and rapid thermal annealing (RTA) process, are investigated. The distinct morphologies of PT thin films without PVAc and with PVAc-assisted suggest different reaction mechanisms. The RTA PVAc-assisted PT thin films can reach to a good property at optimal thermal treatment temperature. The results prove that PVAc can promote the densification and grain growth of PT thin films in RTA process.

SiO2 porous thin films were prepared using polyvinyl alcohol as a template. Trimethylchlorosilane (TMCS) was used as modification reagent. The effects of TMCS concentration and modification time on dielectric property and morphology were investigated. The dielectric constant and loss of the SiO2 porous thin films decreased with the increases of modification time and TMCS concentration. When the concentration of used TMCS and modification time are 60% and 2 hours, the dielectric constant of porous silica can be lowered to 1.86. AFM analysis shows that the silica films before and after modification possess similar microstructure.

Undoped and Ni-doped barium strontium titanate (BST) thin films have prepared by sol-gel method on a platinum-coated silicon substrate. The structure and dielectric properties of Ni-doped BST thin films were investigated. Results show that grain size of the BST thin films decrease with the increase of Ni content. Dielectric constant and dielectric loss also decrease. As the content of Ni-doped reaches 10 mol%, the dielectric constant, dielectric loss, tunability and FOM are 230.25, 0.015, 30.8% and 20.53, respectively. Ni-doped BST thin films were suitable for tunable microwave devices.

Barium tin titanate Ba(SnxTi1−x)O3 (BTS, x = 0.05,0.1,0.15,0.2,0.25) thin films have been prepared by sol-gel technique on Pt/Ti/SiO2/Si substrates. The influences of Sn content on the evolution of the phase and microstructure of the thin films were examined. Dielectric properties of the thin films were investigated as a function of frequency and direct current electric field. The result shows that the Sn content strongly influences the microstructure and the dielectric properties of the films. This work clearly reveals the highly promising potential of BTS films for application in tunable microwave devices.

The compositionally graded Ba1–xSrxTiO3 films with a fine compositional gradient from BaTiO3 to Ba0.70Sr0.30TiO3 were fabricated on Pt/Ti/SiO2/Si substrates by a sol-gel deposition method. The graded films crystallized into a pure perovskite structure after post-deposition annealing. Dielectric constant peaks, common to a ferroelectric transition, were not observed in the temperature range from -35°C to 190°C, within which the dielectric constant and dielectric loss showed negligible temperature dependence. The improved temperature stability from this type of compositionally graded material is beneficial to applications requiring a wide range of operating temperatures, thereby eliminating the need for environmental controls.

Ferroelectric Ba(Sn0.15Ti0.85)O3 (BTS) thin films were deposited on LaNiO3-coated silicon substrates via a sol–gel process. Films showed a strong (1 0 0) preferred orientation depending upon annealing temperature and concentration of the precursor solution. The dependence of dielectric and ferroelectric properties on film orientation has been studied. The leakage current density of thin films at 100 kV/cm was 7 × 10−7 A/cm2 and 5 × 10−5 A/cm2 and their capacitor tunability was 54 and 25% at an applied field of 200 kV/cm (measurement frequency of 1 MHz) for the thin films deposited with 0.1 and 0.4 M spin-on solution, respectively. This work clearly reveals the highly promising potential of BTS compared with BST films for application in tunable microwave devices.

The effects of the mole concentrations of precursor solution on the microstructure and dielectric properties of sol–gel deposited BaZr 0.35 Ti 0.65 O 3 (BZT) thin films have been investigated. The films were of single perovskite phase with strong (1 0 0) preferred orientation when it were grown on LaNiO 3 buffered Pt/Ti/SiO 2 /Si substrates using a diluted precursor solution. Variation of the precursor solution concentration resulted in a different microstructure and, in turn, affected the dielectric properties of the sol–gel deposited films. The BZT thin film showed a very stable and highly insulative characteristic against applied field. This work clearly reveals the highly promising potential of BZT compared with barium strontium titanium films for application in tunable microwave devices.

The Ba(Zr0.35Ti0.65)O3 (BZT) thin films were deposited via sol-gel process on LaNiO3-coated silicon substrates. XRD showed that the crystallinity of BZT film grown on LaNiO3 coated silicon substrates is better than that of BZT film grown on Pt. Both films showed perovskite phase and polycrystalline structure. The temperature dependent dielectric measurements revealed that the thin films had the relaxor behavior and diffuse phase transition characteristics. The capacitor tuning was about 44% for each BZT film grown on LaNiO3/Pt and Pt electrodes at 1 MHz. Especially, the values of dielectric loss at 1 MHz ranged from ∼0.02 to 0.009 in the bias range of 0 to 514 kV/cm, respectively. The leakage currents density of thin films grown on LaNiO3/Pt and Pt electrodes at 300 kV/cm was about 8.5 × 10−7 and 1.1 × 10−5 A/cm2, respectively. This work demonstrates a potential use of BZT films for application in tunable microwave devices.

The cubic pyrochlore structure of Bi 1.5 Zn 1.0 Nb 1.5 O 7 was investigated. The crystal chemical formula of this material was determined as Bi 1.5 Zn 0.5 (Zn 0.5 Nb 1.5 )O 7 by comparing the calculated theoretical X-ray diffraction intensities with the observed ones. Crystal structure parameters were refined by Rietveld method. The (Bi 1.5−2 y Zn 1+2 y Nb 1.5 )O 7− y crystalline samples were also examined by Raman spectroscopy to look for further short range structural information. The results show that the Nb–O and Zn–O stretching modes in the B site oxide octahedral almost do not change with the chemical constitution changing. It is reasonable that the movable Zn 2+ is inclined to occupy B site first and then enter into A site after the B site was stuffed.

The citrate sol–gel synthesis method has been used to prepare Ba(CoTi)x Fe12−2x O19 (x varies from 0.2 to 1.0 in steps of 0.2) hexaferrites. Several methods such as X-ray diffractometry, scanning electron microscopy (SEM) and network analyzer (HP8753E) have been used to obtain detailed information on the crystallography and microwave properties of the precursor powders calcined at different temperature. The correlations of Co 2+ Ti 4+ substitution, annealing temperature and frequency with complex permeability, permittivity, microwave absorption of Ba(CoTi)x Fe12−2x O19 ferrites have been studied. All the ferrites annealed at 1100 and 1200 ◦ C exhibit significant dispersion in complex permeability. The dispersion in complex dielectric constant is significant for the samples sintered at 1200 and 1100 ◦ C. The variations of reflection loss have been studied as a function of frequency, Co 2+ Ti 4+ content, and thickness of the absorber.

Ba{sub 2}Zn{sub 2-x}Co{sub x}Fe{sub 28}O{sub 46} hexaferrites with x=2.0, 1.6, 1.2, 0.8, 0.4 and 0.0 were prepared by citrate sol-gel process. They were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry-differential scanning calorimetry (TG-DSC). The frequency-response complex dielectric constant and complex permeability of Ba{sub 2}Zn{sub 2-x}Co{sub x}Fe{sub 28}O{sub 46} sintered at 1000-1200 deg. C had been investigated in the range from 100 MHz to 6 GHz. The pronounced natural resonance phenomena were observed in {mu}'' spectrum for the samples annealed at 1100 and 1200 deg. C. The natural resonance frequency of Ba{sub 2}Zn{sub 2-x}Co{sub x}Fe{sub 28}O{sub 46} ferrites was intensively affected by the substitution of Zinc ion and annealing temperature.

The present paper deals with the investigations of the preparation of hexaferrites with Z =0.0, 0.5, 1.0, 1.5, 2.0 by citrate sol–gel process as well as the complex dielectric constant and complex permeability as functions of measuring frequency from 100 MHz to 6 GHz, annealing temperature and composition. The results show that the real part of permeability decreased with frequency increasing for all samples annealed at 1000–1200 °C but Co 2 U ferrite (Ba 4 Co 2 Fe 36 O 60 ). The natural resonance phenomenon is observed in μ ″ spectrum for all hexaferrites with exception for Co 2 U. The natural resonance frequency is a function of annealing temperature as well as composition, which shifts to lower frequency with Zinc content and increasing calcaining temperature.

Ba(ZnTi) x Fe 12−2 x O 19 ( x varies from 0.2 to 1.0 in steps of 0.2) hexaferrites were prepared by citrate sol–gel process, the formation temperature is about 800 °C. The samples were characterized by XRD, scanning electron microscopy. The effect of Zn 2+ Ti 4+ substitution, annealing temperature on complex permeability, permittivity and microwave absorption had been studied for Ba(ZnTi) x Fe 12−2 x O 19 ferrite in the frequency range from 100 MHz to 6.0 GHz. All the ferrites exhibit significant dispersion in complex permeability. The dispersion in complex dielectric constant is not significant. The variations of reflection loss have been studied as a function of frequency, Zn 2+ Ti 4+ content, and thickness of the absorber.

Dielectric relaxation studies have been made in pyrochlore (Bi1.5Zn0.5)(Zn0.5−x/3TixNb1.5−2x/3)O7 ceramics where 0⩽x⩽1.5. The measurements of dielectric constant (e) and dielectric loss ( tan δ ) are made in the frequency range (1–1000 kHz) at various temperatures from −200 to 200°C. Dielectric constant have the highest value of 215 at the x=1.5 composition. Permittivity peaks with obvious frequency dispersion were observed and with the increase of the Ti content, the temperature of the permittivity maximum of each one is shifted to lower temperatures. The results indicated that the dielectric dispersion occurs in low temperature. The relaxation behaviour is characterised in the present paper, the effect of Ti on the dielectric relaxation behaviour and the physical mechanism giving polarization is briefly discussed.

Structure and dielectric properties of pyrochlore solid solutions in the Bi2O3– ZnO –Nb2O5 –S b2O3 (BZNS) system were investigated. The X-ray diffraction technique was used to analyze the phase structure. Also, the atomic valence of Sb in BZNS pyrochlores was confirmed as quinquevalent cation (Sb 5þ ) by X-ray photoelectron spectroscopy. Sb replacing Nb in the series (Bi1.8Zn0.2)(Zn0.6Nb1.42xSbx)O7 leads to lower dielectric constant. With increasing amount of Sb 52 ions substitution ð0 # x # 1:4Þ; the dielectric constant (1) decreases linearly from 100 to 35 associated with a very low loss ðtan d # 4 £ 10 24 Þ: The temperature dependence of dielectric constant varies systematically with x. The ceramics with a temperature coefficient of dielectric constant (a1) less than ^ 15 ppm/8C are reported. The data suggest that the B-site cations play an important role in the determination of dielectric properties for the compounds. q 2002 Elsevier Science Ltd. All rights reserved.

We study the effect of grain size on the dc field dependence of dielectric characteristics in Ba0.6Sr0.4TiO3 ceramics prepared by a sol–gel method. The samples were observed and analysed by SEM and X-ray diffraction. The dielectric constant samples decreases as the applied dc field increases. The influence of the dc field on the loss factor is much less than that on the dielectric constant. With increasing of the applied voltage, the Tc was increased and the peaks were suppressed and broadened. As the grain size increases, The maximum dielectric constant and the percentage change of dielectric constant under a dc field increase. A transition broadening and shift of Tc are observed as grain size decreases.

The electronic structures of pure and Nb 5+ , La 3+ doped ferroelectric PbTiO 3 have been calculated with discrete variation X α (DV-X α ) embedded cluster method. Based on the relative distribution of partial density of states (PDOS) of Ti 4+ , Nb 5+ , La 3+ , and Pb 2+ ions. We could clarify the resistant effect of Nb 5+ , La 3+ doping on the ferroelectric fatigue in PbTiO 3 based material system (PZT).

The Ba0.6Sr0.4TiO3 ceramics doped B2O3-SiO2 glass prepared by a sol-gel process and the effect of glass content on the DC field dependence of dielectric characteristics in Ba0.6Sr0.4TiO3 ceramics were studied. The samples were observed and analysed by SEM and X-ray diffraction. The dielectric constant of a BST sample with 1 mol% B2O3-SiO2 sintered at 1250°C was as good as that of undoped BST sintered at 1340°C. The dielectric constant samples decreases as the applied DC field increases. The influence of the DC field on the loss factor is much less than that on the dielectric constant. With increasing of the applied voltage, the T c was increased and the peaks were surpressed and broadened. With increasing of glass content, the peaks were also surpressed and broadened. The maximum dielectric constant and the percentage change of dielectric constant under a DC field increase.

Antiferroelectric lead lanthanum zirconate stannate titanate (PLZST) ceramic powders with a composition of Pb0.97La0.02(Zr0.65Sn0.25Ti0.10)O3 were synthesized by a modified coprecipitation method, combining solid state reaction and coprecipitation. TGA and DSC were performed to investigate the thermal behavior of precursor mixture, and XRD analysis verified the formation of perovskite phase in powders calined at 750°C/2h. Planetary ball milling was used to reduce the particle size of powders to a sub-micron distribution, and XRF was conducted to analyze the stoichiometry of the calcined powders. A relative density of 97% was achieved from specimens prepared by tape casting technology and sintered at 1150°C/2h. An antiferroelectric double polarization hysteresis with EAFE-FE=4.0kV/mm and a strain hysteresis with maximum longitude strain of 0.4% under 6kV/mm were observed in high field measurements.

Using a metallo-organic solution deposition (MOSD) process, the thicker lead titanate thin films were prepared on platinum-coated silicon substrates. The working solution was synthesized by heating lead acetate and titanium butoxide in a solvent. Then a polymer was mixed into the solution. The thickness of crackfree single PbTiO3 layer is approximately 0.25um. This value is almost three times larger than that of the film prepared by conventional metallo-organic deposition (MOD) methods. The effects of polymer on solution properties and film structures were investigated.

The dielectric properties and transition temperature of relaxor ferroelectric in the (1-x)Pb(Mg1/3Nb2/3)O3-xBaTiO3(x=0.00∽0.90) solid solution series have been investigated. With increasing BT content, the frequency dependence of the transition temperature and the diffuseness of dielectric peak of sintered specimens were increased. The relaxational characteristics of the specimens were decreased with increase in BT content. The change of the transition temperature with BT content in PMN-BT ceramics was in the form of “U” curve. The effects of compositions on dielectric properties may be caused by the presence of paraelectric phase Ba(Mg1/3Nb2/3)O3 in PMN-BT ceramics.

A series of Bismuth-Zinc-Calcium-Niobium oxide compositions with the general formulate of Bi2O3-(Zn1-xCax)O-Nb2O5 (0≤×≤0.5) were synthesized. Dense and uniform ceramic samples were obtained at sintering temperature of 940°C∽1060°C. The structure of these samples varies greatly with the change of compositions by means of XRD analyses. Based on the frequency and temperature dependence of dielectric constant and loss, dielectric properties were studied. It is shown that increasing the value of × decrease dielectric constant and does not result in dielectric loss degradation. Temperature coefficient of dielectric constant increases to positive and the stability of temperature coefficient become better especially in the case of x=0.15, for which the value of stability is just between ±5ppm/°C. Dielectric properties are closely related to phase structure in Bi2O3-(Zn1-xCax) O-Nb2O5 ceramics.

A series of PbTiO 3 glass-ceramics with different grain size has been synthesized by the sol-gel method. The dielectric relaxation of lead titanate glass-ceramics at about 1GHz was investigated. The domain structure in the grain was also observed by SEM, the relationship between dielectric relaxation frequency and grain size was also discussed.

A series of copolymers of vinylidene fluoride (VDF) and trifluoroethylene (TrFE) containing 52-80 mol% VDF have been investigated. The properties of unirradiated and irradiated samples are compared and an abnormal ferroelectric relaxation is observed. Electron irradiation largely changes their properties. An abnormal ferroelectric relaxation is observed in the copolymer containing 80 mol% VDF, in which Curie peak shifts to low temperature with increase of measuring frequency, that is different of the other two kinds of copolymer which show obvious ferroelectric relaxation properties.

Yttrium iron garnet (YIG) powders were prepared by sol-gel process. The synthesis parameters including pH values, molar ratio, reactive temperature and time and annealing treatment were studied for formation reaction of single phase YIG. The transformation of precursor to gel and to crystalline phase were determined by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and X-ray powder diffraction (XRD). The results showed that pure phase YIG powders could be obtained through sol-gel process by controlling the relevant annealing process.

Barium titanate glass-ceramics have been synthesized through sol-gel process. The small bulk transparent gel derived glass was got by heat-treating gel at 600°C. The pure nano-sized barium titanate crystals formed in the glass matrix after the gel derived glass was heated above 700°C. The grain size and structure transition of materials was also studied by using XRD, IR and Raman spectrum. The results indicated that the gels derived glass were easy to be crystallized, the heat-treatment temperature was increased, the crystalline size increased, and the cubic barium titanate transformed as tetragonal perovskite.

This paper was researched hydrostatic pressure-induced phase transition for niobium-doped lead zirconate titanate Pb 0.99 Nb x (Zr 0.95 Ti 0.05 ) 1-x O 3 (x≤ 0.02%) ceramic specimen at room and higher temperature, the pressure dependence of the remnant polarization and dielectric response for the sample were measured at different temperatures, it was found that the phase transition pressure increased with increasing temperature.

Thin films of TiO2-SiO2 were prepared by a sol-gel process. The refractive indices and extinction coefficients of these films as a function of wavelength were calculated using optical transmission spectra. The relationships of the fabricating technology, refractive indices and extinction coefficients were studied. With increasing TiO2 content and heat treatment temperature, the refractive index of the films increased. The relationships between the surface roughness, coating layer number, optical propagation loss and preparation technology were studied.

PZT(50/50) ferroelectric thin films were deposited by the sol-gel method. The refractive index emerging from Si(111) and fused quartz glass substrates were measured and calculated by ellipsometry and optical transmission spectra, respectively. The relationship between structure and refractive indices was studied. Alter heat treatment the PZT films on silicon and platinized silicon substrates revealed that the structure plays a major role in variation of the refractive index. The optical waveguide losses of thin films were measured using the prism-waveguide coupling technique. The relationship between optical waveguide loss and preparation technology were also studied. The waveguide loss of the films is increased with increasing of the heat treatment temperature. With increasing of coating thickness the waveguide loss is not significantly increased.

Pinning effect of lead lanthanum titanate (PLT) ferroelectric thin films with excess PbO of 20 mol% has been studied for deposition on different substrates. Silicon, sapphire and quartz were used as substrates on which Pt/Ti or LaNiO3 thin films were deposited as bottom electrodes. Electron probe analysis results showed that there was still a certain amount of excess Pb in PLT films after annealing at 550 ?C for 1 h, and the amount of it was dependent on the substrate used. The distribution of excess Pb in the films was investigated by Auger electron spectroscopy depth profile. It was shown that the substrates and the bottom electrodes had significant effects on the content and distribution of excess Pb in PLT films. The excess Pb and its accumulation at the interface between the film and bottom electrode may act as pinning centers and have a pinning effect on domains, which can be observed by abnormal P-E hysteresis loops and abnormal C-V curves. The excess Pb content in the films and the accumulation of Pb at the interface were high in PLT films deposited on Pt/Ti/Si, and considerable pinning effect was observed. As LaNiO3 would absorb most part of the excess Pb in PLT films, the content of excess Pb in the films deposited on LaNiO3/Si was very low and the pinning effect was hardly observed.

Porous silica gel and glass were prepared through sol-gel process from tetraethoxysilane (TEOS). The nature and structure of dense gel were studied by means of TEM and Nitrogen Adsorption-deadsorption method. The porous property of gel can be achieved by measuring the pore size distribution. Nucleation and growth of primary gel particles were observed by TEM. Various gel structure were obtained by adding different kinds of catalysts. In accordance with the changing of the gel structure, the porous properties of gels were achieved by measuring the pore size distribution.

In this paper, the nanosized II–VI compound semiconductor ZnS, CdS, CdSe, CdxHg1-xTe (x=1–0.7) crystallites doped silica gel glass was prepared through two step sol-gel process. The optical absorption spectra and transmission spectra were obtained. The optical band gap energy was calculated by the optical absorption spectra and it is larger than that of the bulk materials.