Ti-Doped AgNbO3 as Novel Dense Diffusion Barriers of Limiting Current Oxygen Sensors.

The oxygen sensors with limiting current derived from a dense diffusion barrier have an excellent advantage of detecting oxygen partial pressure by controlling the ratio of air and fuel in combustion environments. Therefore, AgNb1-xTixO3-δ (wherein x varies from 0.1 to 0.3) was prepared as such a dense diffusion barrier layer for sensor application. Among the investigated compositions as a new condensed barrier for the diffusion of sensors, AgNb1-xTixO3-δ (x = 0.1, 0.2, 0.3) exhibits oxygen ionic conductivities from 1.37 × 10-4 to 5.78 × 10-3 S·cm-1 in the temperature range of 600-900 °C and outstanding stable electrochemical properties. Herein, we employ these novel materials as dense diffusion barriers and 8 mol % zirconia stabilized by yttria (8YSZ) as a solid-state electrolyte for the fabrication of the oxygen sensors with limiting current. We observed a direct connection between the limiting current and oxygen content within the interval of 0.5-5.0 mol % at 800 °C and a low working voltage. The increase of Ti-doping amount in AgNbO3 accelerates the sensing response to oxygen gas and promotes the service life of the sensor.

Conductivity and aging behavior of Sr(Ti0.6Fe0.4)1-x O3-δ mixed conductor materials.

Perovskite materials play a significant role in oxygen sensors due to their fascinating electrical and ionic conductivities. The sol-gel technique was employed to prepare various compositions of B-site-deficient Fe-doped SrTiO3 (iron-doped strontium titanate) or Sr(Ti0.6Fe0.4)1-x O3-δ , where x = 0.01, 0.02, and 0.03. The XRD results revealed that the principle crystalline phase of the samples was the cubic perovskite structure. The B-site deficiency improved the ionic and total conductivities of Sr(Ti0.6Fe0.4)1-x O3-δ . A small polaron conduction behavior occurred in the total electrical conductivity. The XPS results showed that the oxygen vacancy value decreased with the rise in the amount of B-site deficiencies. A lower B-site deficiency amount could produce more oxygen vacancies in the lattice but resulted in the ordering of vacancies and then lower ionic conductivity. The aging behavior was caused by the ordering of oxygen vacancies and resulted in a degeneration of electrical features under a long service time. Conversely, augmentation of the B-site deficiency amount inhibited the tendency for the ordering of oxygen vacancies and then promoted the electrical performance under a long usage time. The conduction mechanism of oxygen ions through oxygen vacancies was thoroughly investigated and discussed. The current study presents a feasible approach to ameliorate the physical features of conductors through doping the B-site of the perovskite layer with Fe, which would be a fruitful approach for numerous applications, including oxygen sensors and fuel cells anodes.

Y-doped CaZrO3/Co3O4 as novel dense diffusion barrier materials for a limiting current oxygen sensor.

Herein, we illustrate a feasible strategy to strengthen the gas sensing of Y-doped CaZrO3 (YxCa1-xZr0.7O3-δ (x = 0.05, 0.06, and 0.07))/0.1Co3O4 used as sensing materials. This compound was prepared via a solid-state reaction technique. The structural, morphological, electrical, and sensing features such as phase identification, microstructure, ionic conductivity, total conductivity and sensitivity of the fabricated sensors were evaluated via X-ray diffraction, scanning electron microscopy, electron-blocking method, electrochemical impedance spectroscopy and cyclic voltammetry. In addition, the influence of the Y-dopant on the properties of YxCa1-xZr0.7O3-δ/Co3O4 was thoroughly studied. XRD results revealed the formation of the orthorhombic perovskite phase of YxCa1-xZr0.7O3-δ. Moreover, the obtained results from the electrical properties elucidated high electronic and low ionic conductivities, and small polaron conduction of YxCa1-xZr0.7O3-δ/Co3O4. Furthermore, the results confirmed an excellent limiting current plateau for the fabricated oxygen sensor based on YxCa1-xZr0.7O3-δ/Co3O4. In particular, experimental observation indicates that Y-doping at the Ca site and/or Zr site might be difficult.

Conductivity and mixed conductivity of a novel dense diffusion barrier and the sensing properties of limiting current oxygen sensors.

First-principles calculations were used to explore the effect of various Y-doping levels on the electrical conductivity of SrTiO3. Herein, we prepared ((Y0.07Sr0.93Ti0.6Fe0.4-xO3-δ)/x/3Co3O4 (x = 0.1, 0.2, 0.3)) composites using a solid state reaction method. The properties of these sensing materials and the fabricated sensors including crystal phase composition, microstructures, oxygen ionic conductivity, total conductivity and sensor performance were investigated in detail. XRD demonstrates the formation of a highly cubic perovskite structure. The introduction of Co3O4 promotes remarkably the electronic conductivity of the Y0.07Sr0.93Ti0.6Fe0.4-xO3-δ/x/3Co3O4 composites due to the formation of n-type CoO and p-type Co2O3. A limiting current oxygen sensor based on (Y0.07Sr0.93Ti0.6Fe0.4-xO3-δ)/x/3Co3O4 as a dense diffusion barrier shows excellent sensing performance. The recovery time is less than the response time, indicating that Co2O3 promotes the gas desorption reaction which results in a shorter recovery time. The obtained results demonstrate a direct relationship between limiting current (IL) and oxygen content.

Protein-based alignment in 3D-QSAR of FBPase inhibitors.

Three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were performed on Frusectose-1, 6-bisphosphatase (FBPase) inhibitors, based on molecular docking obtained by using GOLD and comparative molecular field analysis (CoMFA). Three random splits into training and test sets had been performed and the high leave-one-out (LOO) cross-validated correlation coefficients q(2) of 0.781, 0.725 and 0.801, respectively, revealed that the models are useful tools for the prediction of test sets as well as newly designed structures against FBPase activity. The superimposed CoMFA models on the receptor site of FBPase are guiding the design of potential inhibitory structures directed against FBPase activity.

[Comparative study on trace elements in Elsholtzia bodineri Vaniot. from Honghe by FAAS].

In the present paper, the authors prepared all the samples by the same method, and optimized the work conditions for flame qtomic absorption spectrometry. FAAS was applied to determine the trace elements, such as Pb, Cr, Cd, Cu, Zn, Hg, Se etc, in Elsholtzia bodineri Vaniot. from Mengzi, Shiping, Mile and Jianshui located in Honghe state. The method is simple, rapid and accurate, and allows simultaneous determination of many elements. The recoveries were in the range of 98.7%-116.4%, and RSD was 0.07%-1.69%. The contents of Pb, Cd and Hg were 53.47, 6.03 and 7.68 microg x g(-1), respectively, in the sample from Jianshui, and were higher than those from other areas. The content of Mn was the highest, and was higher in Mengzi than in other areas, and the average content in the four samples was 913.48 microg x g(-1), which was higher than the content in the soil. Fe is the semi-microelement whose average content in Elsholtzia bodineri Vaniot. from Honghe was 688.46 microg x g(-1), the high-to-low content sequence of Fe in terms of location was Mengzi, Mile, Shiping and Jianshui. The average content of Zn was 116.64 microg x g(-1), and the highest one was from Shiping. But we did not obtain the data of Se in the Elsholtzia bodineri Vaniot. from Honghe state by AAS, and did not detect Hg in samples from Shiping and Mile. The content of the detected elements in Mengzi's sample had the sequence as follows; Mn > Fe > Zn > Pb > Cu > Cr > Cd > Hg>Se, while the sequence was Mn > Fe > Zn > Pb > Cu > Hg > Cd > Cr > Se in the sample of Jianshui, Mn > Fe > Z n >Pb > Cu > Cd > Cr > Hg > Se in Shiping, and Fe > Mn > Zn > Pb > Cu > Cd > Cr > Hg > Se in Mile. The results show that the content of the trace elements is high, especially, Mn, Fe and Zn, in Elsholtzia bodineri Vaniot. in Honghe. Therefore, Elsholtzia bodineri Vaniot., which can be used as drug or beverage, is worth exploitation.

Angiotensin II induced cardiac hypertrophy is blocked by PTEN via suppressing Ca2+/Calcineurin pathway / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effects of PTEN on Ang II induced cardiomyocyte hypertrophy and subsequent Ca(2+)/Calcineurin pathway changes.</p><p><b>METHODS</b>Primary cultured neonatal rat cardiomyocytes were cultured and were treated with phosphate-buffered saline, empty adenovirus (Ad-GFP), or adenovirus encoding for PTEN (Ad-PTEN-GFP) for 48 h and Ang II (10(-7) mol/L) was added to the medium for another 24 h. Cells were harvested and intracellular Ca(2+) concentration ([Ca(2+)] i) was determined by Fura-2/AM ratio imaging analysis; PTEN, ANF, beta-MHC and CaNAbeta mRNA evaluated with RT-PCR; PTEN and CaNAbeta protein by Western blot; CaN phosphatase activity by CaN detecting kits.</p><p><b>RESULTS</b>PTEN at mRNA and protein levels were significantly higher in Ad-PTEN-GFP treated cardiomyocytes than that of Ad-GFP treated cardiomyocytes. Ang II stimulation upregulated [Ca(2+)] i, CaNAbeta at mRNA and protein levels and CaN phosphatase activity in Ad-GFP treated cardiomyocytes but not in Ad-PTEN-GFP treated cardiomyocytes.</p><p><b>CONCLUSIONS</b>Cardiac hypertrophy induced by Ang II could be blocked by PTEN overexpression via suppressing Ca(2+)/Calcineurin pathway.</p>

The relationship between expressions of beta1-, beta2-, beta3-adrenoceptor mRNA of myocardium and cardiac function in patients with heart failure / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the alteration of expressions of beta(1)-, beta(2)-, beta(3)-adrenoceptor mRNA in human myocardial tissue and the relation between their expressions and cardiac function in patient with heart failure.</p><p><b>METHODS</b>The mRNA expressions of beta(1)-, beta(2)- and beta(3)-adrenergic receptors in myocardial tissue were analyzed by using the reverse transcriptase-polymerase chain reaction in 24 patients with heart failure of valvular heart disease and 5 control subjects.</p><p><b>RESULTS</b>Beta(1)-adrenergic receptor mRNA expressions in myocardium were significantly lower in patients with heart failure than those in control subjects, and progressively reduced with aggravation of heart function. By contrast, beta(3)-adrenoceptor mRNA expressions were significantly higher in patients with heart failure than those in controls, and progressively elevated with aggravation of cardiac function. No difference was observed in beta(2)-adrenergic receptor among all groups.</p><p><b>CONCLUSION</b>The changes of beta-adrenergic receptor mRNA expression are associated with the severity of heart failure.</p>

PTEN negatively regulates isoproterenol-induced cardiac hypertrophy and effects of captopril on PTEN expression / 中华心血管病杂志

<p><b>OBJECTIVE</b>To examine the negative regulation role of PTEN in isoproterenol-induced cardiac hypertrophy by testing the expression of PTEN mRNA and protein and to explore the effects of captopril (Cap) on PTEN expression.</p><p><b>METHODS</b>Twenty four rats were randomly divided into three groups: control group, ISO group, and ISO+Cap group. The following parameters were examined:body weight (BW), heart weight (HW), left ventricular weight (LVW), left ventricular end-diastolic pressure (LVEDP), left ventricular end-systolic pressure (LVESP) and +/- dp/dt(max). The ratio of HW/BW and LVW/BW was calculated. PTEN mRNA and protein were tested by RT-PCR and Western blot, respectively.</p><p><b>RESULTS</b>(1) Compared with the control group, the ratio of HW/BW and LVW/BW, LVEDP and LVESP were all increased in ISO group and ISO+Cap group (P < 0.05), but +/- dp/dt(max) was decreased (P < 0.05); (2) compared with the ISO group, the ratio of HW/BW and LVW/BW, LVEDP, LVESP were all decreased in ISO+Cap group (P < 0.05), but +/- dp/dt(max) was increased (P < 0.05); (3) compared with the control group, PTEN mRNA and protein were up-regulated in ISO group and ISO+Cap group; (4) compared with the ISO group, PTEN mRNA and protein were up-regulated in ISO+Cap group.</p><p><b>CONCLUSIONS</b>PTEN mRNA and protein are up-regulated in isoproterenol-induced cardiac hypertrophy. Captopril can up-regulate PTEN expression in cardiac hypertrophy. There is a negative regulative mechanism in cardiac hypertrophy process, in which PTEN is probably an endogenous negative regulator of cardiac hypertrophy.</p>