PT Samples Research Articles

Pregnanetriol in the Range of 1.2-2.1 mg/m(2)/day as an Index of Optimal Control in CYP21A2 Deficiency.

Auxological data is the gold standard index of the therapeutic condition in CYP21A2 deficiency over a long-range period, whereas urinary pregnanetriol for 24 h (PT) is variable for a shorter-range period. Ideal PT levels in comparison with auxological data have not been reported. The main purpose of this study was to analyze ideal PT values as an index of optimal control for CYP21A2 deficiency. First, inter-daily fluctuation of PT was analyzed in one participant. PT levels were distributed over a wide range of 0.44–14.7 mg/day (n=42) in this participant, suggesting that the therapeutic condition should be judged by multiple PT samples. Second, the therapeutic periods of 15 participants with CYP21A2 deficiency were classified using auxological data and Cushing-like symptoms, and the PT levels were analyzed in each period retrospectively. The 95% confidence intervals for the means of the PT levels in the excessive, good and poor control periods were 0.03–1.25 (n=26), 1.23–2.09 (n=116), and 5.35–8.37 (n=72) mg/m2/day, respectively. In conclusion, 1.2–2.1 mg/m2/day of PT values can be used as an index of optimal control in CYP21A2 deficiency.

Interaction of platinum and molybdophosphoric heteropoly acid under conditions of catalyst preparation for benzene oxidation to phenol with an O2-H2 gas mixture

The transformations of platinum and a heteropoly acid (HPA) in binary systems prepared from H2PtCl6 or H2PtCl4 and H3PMo12O40 were studied using IR and UV-VIS spectroscopy, elemental analysis, XPS, EXAFS, TPR, and HREM. The calcination of platinum chloride with the HPA to 450°C resulted in the formation of a platinum salt of the HPA along with decomposition products (mixture I). The reduction of calcined samples containing Pt: HPA = 1: 1 with hydrogen at 300°C (mixture II) followed by exposure to air resulted in the regeneration of the HPA structure. The resulting solid samples of Pt 1−n 0 Pt n II ClmOxHy) (H3+p PMo 12−p VI Mo p V O40) (III) contained platinum and molybdenum in both oxidized and reduced states. The following association species were isolated from mixtures I and II by dissolving in water: [Pt n II PMo12O40] (I s) (n = 0.3−0.8) and [Pt n 0 PMo 12 red O40] (II s) (n ≈ 1). Under exposure to air, the solutions of I s were stable (pH ∼2), whereas Ptmet was released from II s. After the drying of I s, the solid association species (Pt n II ClmOxHy). (H3PMo12O40), where n = 0.3−0.8, m = 0.2−1, and x = 3−0, (I solid) were obtained. The I solid/SiO2 supported samples were prepared by impregnating SiO2 with a solution of I s and drying at 100°C. Platinum metal particles of size ∼20 A and a mixed-valence association species of platinum with the HPA were observed after the reduction of I solid/SiO2 with hydrogen at 100–250°C. These samples were active in the gas-phase oxidation of benzene to phenol at 180°C with the use of an O2-H2-N2 mixture.

Practical uses of proficiency testing as valuable tools for validation and performance assessment in environmental analysis

Besides their role as an external quality control tool, PT results or samples could be used as an alternative to fulfil some of the quality assurance requirements such as analytical precision, uncertainty assessment, and internal quality control. This additional use of proficiency testing could help laboratories to reduce the financial impact of their quality assurance process. The purpose of this paper is to highlight some practical uses of PT results or samples in the environmental analytical field, which have been implemented at ISSeP (Institut Scientifique de Service Public), either for method validation or for internal quality control.

Dielectric tunability and imprint effect in Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics

Abstract For (1 − x )Pb(Mg 1/3 Nb 2/3 )O 3 - x PbTiO 3 , composition dependence of dielectric tunability under the dc bias field and dielectric hysteresis during the circle of external electric field were studied. The highest dielectric tunability of 71% (at the dc bias of 1000 V/mm) and the lowest dielectric hysteresis were observed in the 0.9PMN-0.1PT sample. The effect of circled electric field on the dielectric hysteresis was more remarkable than that on the dielectric aging. Moreover, the effect of the filed-cooled process on the ferroelectric properties was also investigated. In the polycrystalline 0.7PMN-0.3PT sample cooled under a strong dc electric field, a remarkable imprint effect was reported. The preferred direction induced by a strong external electric field was partially reserved after removing the electric field. This imprint effect and the dielectric hysteresis have been tentatively interpreted by reorientation and alignment of polar vectors.

Grain Growth Control and Solid‐State Crystal Growth by Li2O/PbO Addition and Dislocation Introduction in the PMN–35PT System

Grain growth behavior and solid‐state single crystal growth (SSCG) in the Pb(Mg1/3Nb2/3)O3–35 mol% PbTiO3 (PMN–35PT) system have been investigated with varying Li2O/PbO ratios. The effect of dislocation density on crystal growth has also been studied. For SSCG, a BaTiO3 single‐crystal seed was embedded in a polycrystalline PMN–PT matrix. During annealing, a PMN–PT single crystal grew from the seed at the cost of the small matrix grains. Addition of Li2O dopant first enhanced and then reduced abnormal grain growth in the matrix. In the 2 mol% Li2O and 6 mol% PbO excess PMN–PT samples annealed at 1200°C, considerable single‐crystal growth occurred without formation of abnormally large grains in the matrix. Increasing the dislocation density in the BaTiO3 seed crystal resulted in enhanced growth of single crystals. These results were explained in terms of interface reaction‐controlled nucleation and growth, based on crystal growth theories.

MICROSTRUCTURES AND ELECTRICAL PROPERTIES OF PMNT CERAMICS DOPED WITH LITHIUM FLUORIDE

ABSTRACT Microstructures and electrical properties of 0.68Pb(Mg1/3Nb2/3)O3–0.32PbTiO3 (PMNT-0.32PT) ceramics with lithium fluoride additives were investigated. All the samples sintered at 1000°C exhibited the maximum density. LiF plays an important role in the ceramic densification. The dielectric loss of the sample with LiF addition is higher than that of pure PMN-0.32PT ceramic and the samples with LiF addition have more apparent diffusion phase transition than pure PMN-0.32PT sample, all these may be ascribed to anionic (F-O2−) substitution. The lithium fluoride added PMN–0.32PT ceramics sintered at 1000°C have higher piezoelectric constant, which is about 500pC/N.

Magnitudes and Orientations of 31P Chemical Shielding Tensors in Pt(II)−Phosphine Complexes and Other Four-Fold Coordinated Phosphorus Sites

31P MAS and double-quantum filtered 31P MAS NMR experiments at and near the n = 0 rotational resonance condition, as well as off-magic angle spinning 31P NMR experiments on two polycrystalline samples of Pt(II)-phosphine thiolate complexes are reported. Numerical simulations yield complete descriptions of the two 31P spin pairs. 195Pt MAS NMR spectra are straightforward to obtain but sensitively reflect only some parameters of the 195Pt(31P)2 three-spin system. Based on the 31P NMR results obtained and in conjunction with a large body of literature data and irrespective of the chemical nature of the specimen, a unified picture of the dominating motif of 31P chemical shielding tensor orientations of phosphorus sites with 4-fold coordination is identified as a local (pseudo)plane rather than the directions of P element bond directions.

Pb VOLATILIZATION EFFECT ON DIELECTRIC AND PIEZOELECTRIC PROPERTIES IN A Ta-DOPED PMN-PT CERAMIC THICK DISK

A thick ceramic disk of 0.7 Pb ( Mg 1/3( Nb 0.9 Ta 0.1)2/3) O 3-0.3 PbTiO 3 ( PMNT - PT ) was prepared by columbite precursor method with PbO powder buffer surrounding the disk during the sintering process. The dielectric and piezoelectric properties and the microstructure of PMNT - PT samples cut from the different depths of the disk are studied. The phase purity is homogenous in the whole disk within our x-ray diffraction resolution. The dielectric constants, and the piezoelectric effect, d 33, vary with different samples. The samples cut from the middle parts of the disk have the higher d 33. It is believed that the sample processes, especially the Pb volatilization is responsible for these results.

Sub-micrometre imaging of metal surface corrosion by scanning Kelvin nanoprobe.

The detection of the initial changes in the surface microstructure and local chemical properties connected to the corrosion process is possible using a high-resolution scanning Kelvin nanoprobe. This technique provides the simultaneous imaging of the topographical features and potential distribution across a surface at the sub-micrometer level. Nanoprobe measurements performed on samples of Al, Cu, Fe, Ni, Ag and Pt before and after exposure to different corroding solutions reveal the significant changes that take place during the first stages of the corrosion process. The similarities of the images obtained subsequent to corrosion are reflective of surface fractal behavior.

Evidence of decoupled lattice distortion and ferroelectric polarization in the relaxor systemPMN−xPT

We report high q-resolution neutron scattering data on $\mathrm{PMN}\ensuremath{-}x\mathrm{PT}$ single crystals with $x=20%$ and $27%.$ No rhombohedral distortion occurs in the 20PT sample for temperatures as low as 50 K. On the other hand, the 27PT sample transforms into a rhombohedral phase below ${T}_{C}\ensuremath{\sim}375\mathrm{K}.$ Our data provide conclusive evidence that a phase with an average cubic lattice is present in the bulk of this relaxor system at low PT concentration, in which the ferroelectric polarization and lattice distortion are decoupled. The rhombohedral distortion is limited to the outermost tens of microns of the crystal.

Structural effects of Li and K additives on the columbite precursor and 0.9PMN–0.1PT powders

Single-phase perovskite 0.9Pb(Mg 1/3Nb 2/3)O 3–0.1PbTiO 3 (PMN–PT) powders were prepared by using a Ti-modified columbite precursor (MN T) obtained by the polymeric precursor method. The innovation consists in the preparation of Ti-modified columbite in order to react directly with a stoichiometric amount of PbO to obtain pyrochlore-free PMN–PT powders. It has been shown that titanium oxide forms a solid solution with columbite (MN) and does not affect the obtaining of a single-phase columbite precursor. Thus, a high amount of perovskite phase can be obtained by reaction with PbO at 800 °C for 2 h. Effects of K and Li additives on the structure of MN T and PMN–PT were studied. X-ray diffraction studies were carried out to verify the phase formation at each processing step and these data were used for structural refinement by the Rietveld method. Both K and Li additives increase the crystallinity of MN T powders, being this effect more intense for the Li-doped samples. For PMN–PT samples the additives cause an insignificant decrease in the amount of perovskite phase. The morphology of the PMN–PT powder depends on the type of the additive.

Diffusion‐Induced Interface Migration and Mechanical Property Improvement in the Lead Magnesium Niobate–Lead Titanate System

Diffusion–induced interface migration (DIIM) is a technique for modifying the microstructure and mechanical properties of ceramics. In the present study, we investigated DIIM in 0.65Pb(Mg1/3Nb2/3)O3·0.35PbTiO3 (mol fraction) (PMN–PT) ceramics and its effect on mechanical properties. PMN–PT samples were fabricated using the Columbite precursor method and then surface–modified by heat treatment after packing with PbTiO3 powder to induce DIIM. Evaluation of mechanical properties using Hertzian indentation and Vickers indentation showed that the critical load for yielding and surface hardness of the PbTiO3–packed PMN–PT samples were higher than those of the unpacked samples. Thus, the mechanical properties were improved in the samples with a DIIM layer. These results showed that the reliability of mechanical properties of PMN–PT samples is improved by inducing DIIM at the surface.

The influence of Cd doping on the surface acoustic wave properties of Sm-modified PbTiO 3 ceramics

The Sm-modified lead titanate ceramics with a composition of (Pb 0.85− x Cd x Sm 0.1)(Ti 0.98Mn 0.02)O 3; x=0.01–0.08 were prepared by conventional mixed-oxide method. Dielectric and piezoelectric properties of these doped ceramics were measured at room temperature. Microstructural and phase content analyses have been carried out using SEM and XRD. The Curie point versus the amount of Cd composition was also investigated. Surface acoustic wave (SAW) properties, including phase velocity, electromechanical coupling coefficient and temperature coefficient of frequency, were measured. The experiments successfully showed that Cd additive is helpful to obtain higher phase velocity and high electromechanical coupling coefficient, and improve the temperature coefficient of frequency (TCF). In addition, it also reduces the sintering temperature of processing. The SAW properties of our samples ( V p , IL, k 2, and TCF) compare well to the commercially-made PZT and PT samples.

Segregation during the vertical Bridgman growth of lead magnesium niobate–lead titanate single crystals

Transparent, high-quality lead magnesium niobate–lead titanate, (1− x)PbMg 1/3Nb 2/3O 3– xPbTiO 3, or PMNT, crystals were grown using the vertical Bridgman method. Crystals grown from 35% PT ( x=0.35) and 32% PT ( x=0.32) melts were found to vary in composition along the axial direction (from 30% to 72% PT along the growth direction). Crystals grown from 10% PT melts were found to be uniform in composition. Effective segregation coefficients were determined. All crystals examined had uniform radial composition profiles, indicating a flat growth interface. Dielectric measurements were performed on (0 0 1) oriented samples cut from a crystal grown from a 35% PT melt. Powder X-ray diffraction analysis revealed the presence of a two-phase region (tetragonal and rhombohedral) between 31% PT and 36% PT. Poling was performed on (0 0 1) samples of composition 32% PT. Upon poling, as-grown, cloudy crystals became optically transparent, and observations under crossed polarizers showed the formation of large single domain regions. Analysis of 32% PT samples showed a transition from two phases (rhombohedral and tetragonal) in the as-grown sample to single phase (rhombohedral) after poling. The high-temperature phase diagram for PMNT was estimated using a combination of differential thermal analysis and compositional data from growth experiments.

Strontium doping effects on the characteristics of Sm-modified PbTiO3 ceramics

Abstract In this paper, Sr dopants are introduced in the Sm-modified lead titanate (PbTiO 3 ) ceramic systems with a composition of (Pb 0.88− x Sr x Sm 0.08 )(Ti 0.98 Mn 0.02 )O 3 ; x =0.05–0.25 using conventional mixed-oxide method. Dielectric and piezoelectric properties of these doped ceramics were measured at room temperature. Microstructural and compositional analyses have been carried out using scanning electron microscope (SEM) and X-ray diffraction (XRD). The Curie point versus the amount of Sr composition was also investigated. Surface acoustic wave (SAW) properties, including phase velocity and electromechanical coupling coefficient, were measured. The experiments successfully showed that Sr additive is helpful to obtain higher phase velocity and high electromechanical coupling coefficient. The SAW properties of our samples ( V p , k 2 ) are better than the commercially-made PZT and PT samples.

The piezoelectric and dielectric properties of Ca-additive Sm-modified PbTiO3 ceramics intended for surface acoustic wave devices

Abstract Sm-modified lead titanate ceramics with a composition of (Pb 0.88− x Ca x Sm 0.08 )(Ti 0.98 Mn 0.02 )O 3 ; x =0.11∼0.17 were prepared by conventional mixed-oxide method. The dielectric and piezoelectric properties of these doped ceramics were measured at room temperature. Microstructural and compositional analyses have been carried out using SEM and XRD. The Curie point ( T c ) was studied by measuring the dielectric behavior as a function of temperature. The experiments successfully showed that Ca additive not only reduce the lattice anisotropy but is also helpful in providing a higher thickness electromechanical coupling coefficient, k t (>0.57), than that of conventional PbTiO 3 based ceramics while still keeping a small planar electromechanical coupling coefficient, k p . In addition, the Ca additive produced a higher phase velocity and high electromechanical coupling coefficient. The SAW properties of our samples ( V p and k 2 ) are better than those of commercially-made PZT and PT samples.

Effects of strontium on the surface acoustic wave properties of Sm-modified PbTiO 3 ceramics

The Sm-modified lead titanate ceramics with a composition of (Pb 0.88− x Sr x Sm 0.08)(Ti 0.98Mn 0.02)O 3; x=0.05–0.25 were prepared by conventional mixed-oxide method. Surface acoustic wave (SAW) properties, including phase velocity, electromechanical coupling coefficient and temperature coefficient of frequency, were measured. The experiments successfully showed that Sr additive is helpful to obtain higher phase velocity and high electromechanical coupling coefficient. The SAW properties of our samples ( V p , k 2) are better than some commercially-made PZT and PT samples.

Genetic Diversity of Rhizoctonia solani AG-3 from Potato and Tobacco in North Carolina

Anastomosis group 3 (AG-3) of Rhizoctonia solani (teleomorph = Thanatephorus cucumeris) is frequently associated with diseases of potato (AG-3 PT) and tobacco (AG-3 TB). Although isolates of R. solani AG-3 from these two Solanaceous hosts are somatically related based on anastomosis reaction and taxonomically related based on fatty acid, isozyme and DNA characters, considerable differences are evident in their biology, ecology, and epidemiology. However, genetic diversity among field populations of R. solani AG-3 PT and TB has not been documented. In this study, the genetic diversity of field populations of R. solani AG-3 PT and AG-3 TB in North Carolina was examined using somatic compatibility and amplified fragment length polymorphism (AFLP) criteria. A sample of 32 isolates from potato and 36 isolates from tobacco were paired in all possible combinations on PDA plus activated charcoal and examined for their resulting somatic interactions. Twenty-eight and eight distinct somatic compatibility groups (SCG) were identified in the AG-3 PT and AG-3 TB samples, respectively. AFLP analyses indicated that each of the 32 AG-3 PT isolates had a distinct AFLP phenotype, whereas 28 AFLP phenotypes were found among the 36 isolates of AG-3 TB. None of the AG-3 PT isolates were somatically compatible or shared a common AFLP phenotype with any AG-3 TB isolate. Clones (i.e., cases where two or more isolates were somatically compatible and shared the same AFLP phenotype) were identified only in the AG-3 TB population. Four clones from tobacco represented 22% of the total population. All eight SCG from tobacco were associated with more than one AFLP phenotype. Compatible somatic interactions between AG-3 PT isolates occurred only between certain isolates from the same field (two isolates in each of four different fields), and when this occurred AFLP phenotypes were similar but not identical.

Genetic diversity of Rhizoctonia solani AG-3 from potato and tobacco in North Carolina

Anastomosis group 3 (AG-3) of Rhizoctonia solani (teleomorph = Thanatephorus cucumeris) is frequently associated with diseases of potato (AG-3 PT) and tobacco (AG-3 TB). Although isolates of R. solani AG-3 from these two Solanaceous hosts are somatically related based on anastomosis reaction and taxonomically related based on fatty acid, isozyme and DNA characters, considerable differences are evident in their biology, ecology, and epidemiology. However, genetic diversity among field populations of R. solani AG-3 PT and TB has not been documented. In this study, the genetic diversity of field populations of R. solani AG-3 PT and AG-3 TB in North Carolina was examined using somatic compatibility and amplified fragment length polymorphism (AFLP) criteria. A sample of 32 isolates from potato and 36 isolates from tobacco were paired in all possible combinations on PDA plus activated charcoal and examined for their resulting somatic interactions. Twenty-eight and eight distinct somatic compatibility groups (SCG) were identified in the AG-3 PT and AG-3 TB samples, respectively. AFLP analyses indicated that each of the 32 AG-3 PT isolates had a distinct AFLP phenotype, whereas 28 AFLP phenotypes were found among the 36 isolates of AG-3 TB. None of the AG-3 PT isolates were somatically compatible or shared a common AFLP phenotype with any AG-3 TB isolate. Clones (i.e., cases where two or more isolates were somatically compatible and shared the same AFLP phenotype) were identified only in the AG-3 TB population. Four clones from tobacco represented 22% of the total population. All eight SCG from tobacco were associated with more than one AFLP phenotype. Compatible somatic interactions between AG-3 PT isolates occurred only between certain isolates from the same field (two isolates in each of four different fields), and when this occurred AFLP phenotypes were similar but not identical.

Complete set of material constants of 0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3 domain engineered single crystal

The relaxor based Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZNPT) and Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) domain engineered single crystal systems exhibit superior electromechanical property compared to the conventional PZT ceramics, which have been dominating piezoelectric applications for more than 40 years. The theoretical studies for the physical mechanism of this multi-domain system have generated a great deal of interests in scientific community [1–6]. From both fundamental study and device design purpose, it is necessary to get the complete set of matrix properties for those crystals. Recently, such a complete set of elastic, piezoelectric and dielectric constants has been reported for 0.95Pb(Zn1/3Nb2/3)O3-0.045PbTiO3 (PZN-4.5%PT) and 0.92Pb(Zn1/3Nb2/3)O3-0.08PbTiO3 (PZN-8.0%PT) single crystal systems [7–9]. It is known that PZT4.5%PT single crystal system [2] is fairly far away from the morphotropic phase boundary (MPB) composition, therefore, it does not represent the maximum electromechanical capability of this solid solution system. It has been shown that the PZN-8.0%PT single crystal system possesses much larger piezoelectric strain constant d33 than that of PZT-4.5%PT [9]. The electromechanical coupling coefficient k33 of PZN-8.0%PT could reach 0.94, which is higher than that of PZT-4.5%PT. However, PZN-PT single crystal systems near the MPB composition exhibit strong property fluctuations. We have measured several PZN-8.0%PT samples cut from different parts of the same crystal boule and found that although the fluctuation in PT composition of all samples were within ±2%, the measured value of d33 varied from 2000 to 4000 (pC/N) and the value of eT 33 varied from 5000 to 8000, which makes PZN-8.0%PT single crystal unsuitable for many practical device applications. On the other hand, it is very difficult to control the composition accurately because of the lead loss during growth. Therefore, we focused our attention to 0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3 (PZN-7.0%PT) which has the PT composition slightly away from the morphotropic phase boundary and is in the rhombohedral phase at room temperature. A full set of matrix properties of PZN-7.0%PT was measured and is reported in this paper. The electromechanical coupling property fluctuation was also investigated as a reference for people who will use these material properties. After being poled along [001] of the cubic coordinates at room temperature, the multi-domain PZN-7.0%PT single crystal could be treated as pseudotetragonal 4 mm symmetry [1–10]. For materials with 4 mm symmetry, there are 11 independent material constants altogether: 6 elastic, 3 piezoelectric and 2 dielectric constants. In order to determine them unambiguously, an improved hybrid method combining the advantages of ultrasonic pulse-echo and resonance methods was used. The main ideas of this technique have been given in Refs. [8–11]. In previous measurements, usually e31 and e33 were derived from the measured cE 11, c E 12, c E 13, c E 33, d31 and d33 by using the following equations