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By performing standard positive-up-negative-down, hysteresis-loop and dielectric measurements on the ferroelectric lead zirconate titanate thin-film capacitors subject to bipolar/unipolar electrical cycling, we show that unipolar fatigue is evident though still less severe than bipolar fatigue conducted at the same voltage. That has been attributed to a series of periodic events of polarization backswitching (driven by the residual depolarization field) and switching (driven by the residual applied field) during unipolar electrical cycling, and explained using the LPD-SICI model (LPD-SICI stands for local phase decomposition caused by switching-induced charge injection). The dielectric results have been used to estimate the effective thickness di of the fatigue-induced degraded (pyrochlorelike) interfacial layer after bipolar/unipolar fatigue, which has not been done so far to our best knowledge. The fact that di is still much less than the film thickness even after the most severe bipolar fatigue strongly suggests that polarization fatigue in ferroelectrics is an interface effect, not a bulk one. [ABSTRACT FROM AUTHOR]

We developed a model with no adjustable parameter for retention loss at short and long time scales in ferroelectric thin-film capacitors. We found that the predictions of this model are in good agreement with the experimental observations in the literature. In particular, it explains why a power-law function shows better fitting than a linear-log relation on a short time scale (10-7 s to 1 s) and why a stretched exponential relation gives more precise description than a linear-log plot on a long time scale (>100 s), as reported by many researchers in the past. More severe retention losses at higher temperatures and in thinner films have also been correctly predicted by the present theory. [ABSTRACT FROM AUTHOR]

We classify the switching kinetics of ferroelectrics including both epitaxial/polycrystalline thin films and single-crystalline/ceramic bulks at various applied fields into four categories, depending on whether the depolarization field and/or the polarization reversal induced by the switching promotion effect between adjacent parts can be neglected. We show that our statistical model developed very recently [X. J. Lou, J. Phys.: Condens. Matter 21, 012207 (2009)] in its generalized form applies to all these four categories. Finally, we make the comparison between our model and the conventional Kolmogorov–Avrami–Ishibashi model and discuss the behavior of the switching currents for different n. [ABSTRACT FROM AUTHOR]

The experimental characteristics of polarization fatigue in thin-film, bulk ceramic, and single-crystalline ferroelectrics have been reviewed in detail. Various scenarios and models proposed for fatigue in ferroelectric materials during the past few decades have been discussed, together with our own model developed very recently [Phys. Rev. Lett. 97, 177601 (2006); Phys. Rev. B 75, 244104 (2007)]. Interpretations for the experimental data reviewed in this paper but untreated in our previous work [Phys. Rev. B 75, 244104 (2007)] as well as the methods of improving the fatigue endurance in ferroelectrics are given based on this model. Finally, the results on polarization fatigue in some special classes of ferroelectrics such as multiferroics (e.g., BiFeO3-based materials), ferroelectric polymers, and antiferroelectric thin films and ceramics are discussed and accounted for in light of our model. [ABSTRACT FROM AUTHOR]

We report conformal deposition of both RuO2 electrodes and PbZrxTi1-xO3 (PZT) capacitors in submicron Si trenches through the same in situ liquid source mist processing. The step coverage for the RuO2 electrodes is 75% at 225 °C. After electroding, we deposited Pb(Zr,Ti)O3 thin films and nanotubes using the same apparatus with remanent polarization of ∼15 μC/cm2. The step coverage was 59% on the sidewall and 79% on the bottom wall. Electrical testing showed charge storage (capacitance/trench) was 13±2 pF, with a breakdown voltage of 11.3±0.2 V and dielectric constant [variant_greek_epsilon]=166±30. This shows that a single inexpensive processing can produce fully electroded dynamic random access memory trenched capacitors with high aspect ratios and commercial electrical performance. [ABSTRACT FROM AUTHOR]

The effects of misfit strain on the electrocaloric (EC) properties of BaTiO3 thin films arestudied by using the Landau-Devonshire thermodynamic theory. The 'misfit-strain temperature' phase diagrams for different electric fields are constructed. It was found that the EC effect of a BaTiO3 thin film is strongly dependent on misfit strain. More interestingly, we found that BaTiO3 thin films with tensile misfit strain exhibit a sizable EC effect in a wider temperature range in comparison with those with compressive misfit strain. [ABSTRACT FROM AUTHOR]

Developing lead-free film dielectric capacitors with high-performance of energy storage density, efficiency, fatigue endurance, and thermal stabilities is desirable. Here, we report energy storage properties in (1-x)BaTiO3-xBi3.25La0.75Ti3O12 thin films. It is revealed that a 0.6BaTiO3-0.4Bi3.25La0.75Ti3O12 thin film with a thickness of 280 nm and a crystallization temperature of 650 °C shows a breakdown strength of 3.23 MV/cm with a large polarization value and dielectric constant. An ultrahigh energy storage density of 61.1 J/cm3 and an efficiency of 84.2% are simultaneously achieved at room temperature. Additionally, excellent fatigue endurance after 6 × 109 cycles and good thermal stability up to 150 °C are observed, implying excellent energy storage performance in 0.6BaTiO3-0.4Bi3.25La0.75Ti3O12 thin films. [ABSTRACT FROM AUTHOR]

Thin film ferroelectric capacitors (TFFCs) with excellent energy storage have attracted increasing attention due to the electronic devices toward miniaturization and integration. BiFeO3 (BF)/ Bi3.25La0.75Ti3O12 (BL) based thin films are prepared by chemical solution deposition for energy storage. Ultrahigh energy storage with a recoverable energy density Ure of 54.9 J/cm3 and an efficiency g of 74.4% is observed in the bilayered BF/BL thin films. Further improvement of energy storage is realized in trilayered BL/BF/BL thin films with a Ure of 65.5 J/cm3 and an efficiency g of 74.2% at an electric field of 2753 kV/cm as well as excellent fatigue endurance up to 109 cycles. The results suggest that BF/BL based thin films can be used as lead-free TFFCs in energy storage applications. [ABSTRACT FROM AUTHOR]

Environmentally benign Bi3.25La0.75Ti3O12 (BLTO) thin film capacitors were prepared by a cost effective chemical solution deposition method for high energy density storage device applications. Low annealing temperature annealed BLTO thin films showed very slim hysteresis loops with high maximum and small remnant polarization values. Increasing the applied electric field to 2040 kV/ cm, the optimized BLTO thin films show a high recoverable energy density of 44.7 J/cm3 and an energy efficiency of 78.4% at room temperature. Additionally, the BLTO thin film capacitors exhibited excellent fatigue endurance after 4x108 cycles and a good thermal stability up to 140°C, proving their strong potential for high energy density storage and conversion applications. [ABSTRACT FROM AUTHOR]

Strong evidence suggests that cancer-associated inflammation promotes tumor growth and progression, and interleukin-6 (IL6) is an important modulator of inflammation. However, the roles of IL6 and mutations of its corresponding gene in prostate cancer have not been clearly documented. We retrieved data from the Oncomine database concerning IL6 expression in prostate cancer and its role in prostate-specific antigen (PSA) recurrence. We also performed a case-control study of the IL6 -572G/C polymorphism (rs1800796) in 236 sporadic prostate cancer patients and 256 healthy controls from a southern Han Chinese population. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association between rs1800796 and prostate cancer susceptibility. A dual-luciferase reporter assay was used to test the transcriptional activity of the IL6 promoter G and C alleles. IL6 was overexpressed in prostate cancer tissues compared to normal tissues, especially in those with higher Gleason scores. Moreover, elevated IL6 expression was associated with high PSA recurrence rate in Oncomine data. Our case-control study demonstrated that compared with the -572C allele, the -572G allele conferred a borderline increased risk of prostate cancer (OR = 1.31, 95%CI = 0.99-1.74, P = 0.061). This was more pronounced in the subgroup of individuals having never smoked (OR = 1.85, 95%CI = 1.07-3.22). Moreover, the G allele showed increased activity relative to the C allele in the dual-luciferase reporter assay. Our results suggest that the -572G/C polymorphism may be associated with IL6 expression, which in turn plays a role in prostate cancer development.

This study investigated the role of regulatory T (T(reg)) cells in patients with new-onset, treatment-naïve ankylosing spondylitis (AS). Levels of CD4(+)CD25(high)CD127(low/-) T(reg) cells in the peripheral blood of 14 AS patients and 18 age-matched healthy volunteers were investigated by flow cytometry and correlations with serum levels of immunoglobulin A (IgA) and AS activity, as assessed by the Bath AS Disease Activity Index (BASDAI), were analysed. The number of peripheral blood CD4(+)CD25(high)CD127(low/-) T(reg) cells in AS patients was found to be significantly lower than in healthy controls and was inversely correlated with serum IgA levels. There was no significant correlation between CD4(+)CD25(high)CD127(low/-) T(reg) cell numbers and BASDAI scores. It is concluded that CD4(+)CD25(high)CD127(low/-) T(reg) cells may play a role in the pathogenesis and activity of AS.

To test directly whether fibrin(ogen) is a key binding site for apolipoprotein(a) [apo(a)] in vessel walls, apo(a) transgenic mice and fibrinogen knockout mice were crossed to generate fibrin(ogen)-deficient apo(a) transgenic mice and control mice. In the vessel wall of apo(a) transgenic mice, fibrin(ogen) deposition was found to be essentially colocalized with focal apo(a) deposition and fatty-streak type atherosclerotic lesions. Fibrinogen deficiency in apo(a) transgenic mice decreased the average accumulation of apo(a) in vessel walls by 78% and the average lesion (fatty streak type) development by 81%. Fibrinogen deficiency in wild-type mice did not significantly reduce lesion development. Our results suggest that fibrin(ogen) provides one of the major sites to which apo(a) binds to the vessel wall and participates in the generation of atherosclerosis.

Apolipoprotein(a) [apo(a)] contains a kringle domain(IV) homologous to that of angiostatin, a natural angiogenic inhibitor. Because of this structural similarity we suspected that apo(a) could be an inhibitor of angiogenesis. The possible role of apo(a) in microvascular proliferation was studied in an in vivo quantitative model, the disc angiogenesis system (DAS) and compared to angiostatin. Apo(a) and other test compounds were placed in the center of a polyvinyl alcohol foam disc that was implanted subcutaneously in mice. After 14 days, the disc was removed and vascular growth into the disc was measured. Apo(a) did not affect spontaneous vessel growth into the disc, while angiostatin suppressed this growth and basic fibroblast growth factor (bFGF) increased it. Additionally, apo(a) did not modify the vascular growth induced by bFGF. Transgenic mice expressing the human apo(a) gene were used to study the systemic effect of apo(a): neither an increase nor a decrease in vascular growth was detected. Our results suggest that apo(a) is unlikely to play a significant role in the control of angiogenesis. Furthermore, our experiments confirm the inhibitory effect of angiostatin not only on induced angiogenesis but also on baseline, spontaneous angiogenesis., (Copyright 1998 Academic Press.)

Embryonic and adult muscle express distinct complements of proteins. Transplant experiments have shown that embryonic and denervated muscles can form synapses with foreign neurites, while normal innervated mature muscles cannot, except at the synaptic area. To identify molecular differences between 'innervatable' embryonic muscle and 'non-innervatable' mature muscle, we used a differential immunization method to make monoclonal antibodies that recognize antigens present in embryonic muscle rather than normal mature muscle. Four independent monoclonal antibodies that stain embryonic and mature muscle sections differentially have been obtained. One stains the entire embryonic muscle cell surface but only the synaptic area in mature muscle; 3 stain the entire embryonic muscle cell surface but do not stain mature muscle. The antibodies also stain other embryonic tissues at several stages. The antigens are concentrated in basal laminae and in an extracellular-matrix (ECM) fraction, indicating that they are ECM molecules. The temporal expression of all 4 antigens in developing muscle is coincident with muscle innervation. All antigens exhibit temporal and tissue distributions different from those of any reported muscle proteins, suggesting that novel antigens underlie these patterns. These results confirm that the immature muscle ECM has a distinct molecular composition, and suggest that the presence of these antigens may be part of the molecular basis for the innervatability of embryonic muscle.

To elucidate the sequence of molecular events leading to nerve terminal differentiation, we have examined the regulation of expression of presynaptic protein genes during synapse formation in vivo. In the chick ciliary ganglion (CG), synaptophysin IIa and synaptophysin IIb mRNAs showed threefold increases relative to neurofilament-M mRNA during the time of target contact [Embryonic Day 7 (E7)-E9]. Expression of synaptotagmin I mRNA also increased severalfold over this time interval. Thus, mRNAs for three synaptic vesicle proteins are upregulated coordinately during synaptogenesis. In contrast, the major increase in choline acetyltransferase (ChAT) mRNA (four- to fivefold) occurred between E15 and E20, coincident with the maturation of synapses in the CG. Coincident with ChAT upregulation, there is a switch in the relative abundance of mRNAs encoding vesicle protein isoforms. In particular, mRNAs encoding synaptophysin IIb and synaptotagmin II (which is undetectable at E9) become predominant. Therefore, although synaptic vesicle protein mRNAs are upregulated in a first phase of differentiation at the time of synapse formation, a temporally distinct phase of presynaptic protein gene regulation, associated with the specific maturation of synapses, is also apparent.