Large field-induced strains in a lead-free piezoelectric material

Piezoelectric materials exhibit a mechanical response to electrical inputs, as well as an electrical response to mechanical inputs, which makes them useful in sensors and actuators. Lead-based piezoelectrics demonstrate a large mechanical response, but they also pose a health risk. The ferroelectric BiFeO(3) is an attractive alternative because it is lead-free, and because strain can stabilize BiFeO(3) phases with a structure that resembles a morphotropic phase boundary. Here we report a reversible electric-field-induced strain of over 5% in BiFeO(3) films, together with a characterization of the origins of this effect. In situ transmission electron microscopy coupled with nanoscale electrical and mechanical probing shows that large strains result from moving the boundaries between tetragonal- and rhombohedral-like phases, which changes the phase stability of the mixture. These results demonstrate the potential of BiFeO(3) as a substitute for lead-based materials in future piezoelectric applications.

Hidden magnetic configuration in epitaxial La(1-x) Sr(x) MnO3 films

We present an unreported magnetic configuration in epitaxial La(1-x) Sr(x) MnO3 (x ∼ 0.3) (LSMO) films grown on strontium titanate (STO). X-ray magnetic circular dichroism indicates that the remanent magnetic state of thick LSMO films is opposite to the direction of the applied magnetic field. Spectroscopic and scattering measurements reveal that the average Mn valence varies from mixed Mn(3+)/Mn(4+) to an enriched Mn3+ region near the STO interface, resulting in a compressive lattice along the a, b axis and a possible electronic reconstruction in the Mn e(g) orbital (d(3)z(2)-r(2). This reconstruction may provide a mechanism for coupling the Mn3+ moments antiferromagnetically along the surface normal direction, and in turn may lead to the observed reversed magnetic configuration.

Nutrient composition and degradation profiles of anthocyanidin-accumulating Lc-alfalfa populations

Alfalfa (Medicago sativa L.) is one of the most used forages in the world but suffers the disadvantage of having poor protein utilization by the animal. The poor protein utilization is the result of excessive ruminal protein degradation, which might be reduced by the protein precipitating capacity of anthocyanidin (AC) and condensed tannins (CT). The objective of this study was to determine the effects of the Lc-transgene on survival, anthocyanidin, condensed tannin and chemical profiles in crossed populations of western Canadian-adapted Lc-alfalfa. These were compared with their non-transgenic (NT) parental varieties, Rangelander, Rambler, and Beaver. Lc-alfalfa forage accumulated enhanced amounts of anthocyanidin, with an average concentration of 197.4 µg g-1 DM, while condensed tannins were not detected. Both of these metabolites were absent in the NT parental varieties. Lc-alfalfa had a lower (24.8 vs. 27.3% DM; P < 0.02) crude protein (CP) and higher (58.3 vs. 55.5% DM; P < 0.01) carbohydrate (CHO) concentration, which resulted in their decreased (P < 0.01) N:CHO ratio (68.1 vs. 79.2 g kg-1) compared with NT alfalfa. Slowly degradable N:CHO ratio was decreased by 5.9 g kg-1 (P < 0.03) and total rumen-degradable N:CHO ratio was decreased by 12.9 g kg-1 (P < 0.03) in Lc-alfalfa compared with NT alfalfa. In conclusion, Lc-gene transformation resulted in the accumulation of anthocyanidin, decreased total protein content, increased total carbohydrate content and improved the balance between nitrogen and carbohydrates in the crossed transgenic populations of western Canadian-adapted alfalfa compared to their NT western Canadian parental alfalfa varieties. Key words: Alfalfa, anthocyanidin, Lc-transgene, protein and carbohydrate sub-fractions, nitrogen-to-carbohydrate degradation ratios

Reversible electric control of exchange bias in a multiferroic field-effect device

Electric-field control of magnetization has many potential applications in magnetic memory storage, sensors and spintronics. One approach to obtain this control is through multiferroic materials. Instead of using direct coupling between ferroelectric and ferromagnetic order parameters in a single-phase multiferroic material, which only shows a weak magnetoelectric effect, a unique method using indirect coupling through an intermediate antiferromagnetic order parameter can be used. In this article, we demonstrate electrical control of exchange bias using a field-effect device employing multiferroic (ferroelectric/antiferromagnetic) BiFeO(3) as the dielectric and ferromagnetic La(0.7)Sr(0.3)MnO(3) as the conducting channel; we can reversibly switch between two distinct exchange-bias states by switching the ferroelectric polarization of BiFeO(3). This is an important step towards controlling magnetization with electric fields, which may enable a new class of electrically controllable spintronic devices and provide a new basis for producing electrically controllable spin-polarized currents.

Molecular characterization of long terminal repeat of porcine endogenous retroviruses in Chinese pigs

Pigs offer an unlimited source of xenografts for humans. However, vertically transmitted Porcine endogenous retrovirus (PERV) poses an infectious risk in the course of pig-to-human transplantation. In this study, we characterized PERV long terminal repeat (LTR) sequences from three species of Chinese pigs Banna minipig inbred (BMI), Wu-Zhi-Shan pig (WZSP), and Neijiang pig (NJP-A), and compared them with those of known PERVs (PERV-A, PERV-B, PERV-C, PERV-NIH, and 293-PERV-43). Genomic DNA extracted from peripheral blood mononuclear cells (PBMCs) of the Chinese pigs was used for PCR-amplification, cloning, and sequencing of LTRs. The sequences of BMI and WZSP LTRs were found identical with those of PERV-A and PERV-B, while that of NJP-A LTR was found close to those of PERV-C and PERV-NIH. The gammaretroviral nature of PERV LTRs from Chinese pigs was proved. These LTRs contained also promoter elements including enhancer-like repeats comparable with those of other PERVs. These findings suggested that PERVs from Chinese pigs were similar to PERV-A and PRV-B. Moreover, this study provided new data for the evaluation and selection of pigs to be used in the xenotransplantation.

Suppression of octahedral tilts and associated changes in electronic properties at epitaxial oxide heterostructure interfaces

Epitaxial oxide interfaces with broken translational symmetry have emerged as a central paradigm behind the novel behaviors of oxide superlattices. Here, we use scanning transmission electron microscopy to demonstrate a direct, quantitative unit-cell-by-unit-cell mapping of lattice parameters and oxygen octahedral rotations across the BiFeO3-La0.7 Sr0.3 MnO3 interface to elucidate how the change of crystal symmetry is accommodated. Combined with low-loss electron energy loss spectroscopy imaging, we demonstrate a mesoscopic antiferrodistortive phase transition near the interface in BiFeO3 and elucidate associated changes in electronic properties in a thin layer directly adjacent to the interface.

Interface ferromagnetism and orbital reconstruction in BiFeO3-La(0.7)Sr(0.3)MnO3 heterostructures

We report the formation of a novel ferromagnetic state in the antiferromagnet BiFeO3 at the interface with ferromagnet La(0.7)Sr(0.3)MnO3. Using x-ray magnetic circular dichroism at Mn and Fe L(2,3) edges, we discovered that the development of this ferromagnetic spin structure is strongly associated with the onset of a significant exchange bias. Our results demonstrate that the magnetic state is directly related to an electronic orbital reconstruction at the interface, which is supported by the linearly polarized x-ray absorption measurement at the oxygen K edge.

Utilization of canola seed fractions for ruminants: effect of canola fibre-protein and can-sugar inclusion in dehydrated alfalfa pellets on palatability and lactation performance of dairy cows

This research evaluated the effect of fibre-protein and can-sugar additions to dehydrated alfalfa pellets on feed acceptance, lactation performance, dry matter intake and apparent dry matter digestibility of dairy cows compared with a standard (pure) alfalfa pellet. The results showed that a two:one ratio of fibre-protein to can-sugar mixture can be added at 150 g kg-1 to a standard alfalfa pellet without affecting the palatability and lactation performance of dairy cows, when the alfalfa pellets are included at 50 g kg-1 (as fed basis) of a total mixed ration (TMR). Key words: Canola fractions, fibre-protein, can-sugar, palatability, lactation performances, dairy cows

Platelet hyperreactivity and a prothrombotic phenotype in mice with a gain-of-function mutation in phospholipase Cgamma2

BACKGROUND

Agonist-induced platelet activation involves different signaling pathways leading to the activation of phospholipase C (PLC) beta or PLCgamma2. Activated PLC produces inositol 1,4,5-trisphosphate and diacylglycerol, which trigger Ca(2+) mobilization and the activation of protein kinase C, respectively. PLCbeta is activated downstream of Gq-coupled receptors for soluble agonists with only short interaction times in flowing blood. In contrast, PLCgamma2 becomes activated downstream of receptors that interact with immobilized ligands such as the collagen receptor glycoprotein (GP) VI or activated integrins.

OBJECTIVE AND METHODS

We speculated that PLCgamma2 activity might be optimized for sustained but submaximal signaling to control relatively slow platelet responses. To test this hypothesis, we analyzed platelets from mice heterozygous for a gain-of-function mutation in the Plcg2 gene (Plcg2(Ali5/+)).

RESULTS

Plcg2(Ali5/+) platelets showed enhanced Ca(2+) mobilization, integrin activation, granule secretion and phosphatidylserine exposure upon GPVI or C-type lectin-like receptor-2 stimulation. Furthermore, integrin alpha(IIb)beta(3) outside-in signaling was markedly enhanced in the mutant platelets, as shown by accelerated spreading on different matrices and faster clot retraction. These defects translated into virtually unlimited thrombus formation on collagen under flow in vitro and a prothrombotic phenotype in vivo.

CONCLUSIONS

These results demonstrate that the enzymatic activity of PLCgamma2 is tightly regulated to ensure efficient but limited platelet activation at sites of vascular injury.

Above-bandgap voltages from ferroelectric photovoltaic devices

In conventional solid-state photovoltaics, electron-hole pairs are created by light absorption in a semiconductor and separated by the electric field spaning a micrometre-thick depletion region. The maximum voltage these devices can produce is equal to the semiconductor electronic bandgap. Here, we report the discovery of a fundamentally different mechanism for photovoltaic charge separation, which operates over a distance of 1-2 nm and produces voltages that are significantly higher than the bandgap. The separation happens at previously unobserved nanoscale steps of the electrostatic potential that naturally occur at ferroelectric domain walls in the complex oxide BiFeO(3). Electric-field control over domain structure allows the photovoltaic effect to be reversed in polarity or turned off. This new degree of control, and the high voltages produced, may find application in optoelectronic devices.

Studies on long-term infection of human cells with Porcine endogenous retrovirus

A major concern in pig-to-human xenotransplantations is the potential risk of transmission of Porcine endogenous retroviruses (PERVs) integrated in the pig genome. Our previous work has shown that PERV provirus genes and gag protein can be detected in human embryonic kidney HEK-293 cells during a long-term infection with PERV (Yu et al., Transplant. Proc. 37, 496-499, 2005). In this study, we continued studying the long-term (>6 months) PERV infection of HEK-293 cells. The results showed no significant differences in morphology, growth, apoptosis, and [(3)H]-thymidine incorporation between PERV-infected and uninfected cells. The PERV LTR sequence showed only an insignifcant mutation after the long-term infection. PERV infection had no effect on the transcription of genes of Human endogenous retrovirus (HERV) naturally occurring in HEK-293 cells. Summing up, this study indicated that a long-term PERV infection of HEK-293 cells in vitro does not result in any significant changes in host cells as well as in PERV LTR sequence.

Safety profile of dexlansoprazole MR, a proton pump inhibitor with a novel dual delayed release formulation: global clinical trial experience

BACKGROUND

Dexlansoprazole MR is a dual delayed release formulation of dexlansoprazole, an enantiomer of lansoprazole.

AIM

To assess safety of dexlansoprazole MR in phase 3 clinical trials.

METHODS

Data from 4270 patients receiving dexlansoprazole MR 30 mg (n = 455), 60 mg (n = 2311) or 90 mg (n = 1864); lansoprazole 30 mg (n = 1363); or placebo (n = 896) in six randomized controlled trials and a 12-month safety study were pooled. Safety was assessed via adverse events, vital signs, electrocardiograms, clinical laboratory results and gastric biopsies. Adverse events were summarized per 100 patient-months of exposure to account for imbalances in study drug exposure.

RESULTS

The number of patients with > or =1 treatment-emergent adverse event per 100 patient-months was higher in placebo (24.49) and lansoprazole (21.06) groups than in any dexlansoprazole MR (15.64-18.75) group. Fewer patients receiving dexlansoprazole MR discontinued therapy because of an adverse event (P < or = 0.05 vs. placebo). Seven patients died of events considered unrelated to study drug. Mean serum gastrin rose in all groups except placebo; increases were not dose-related. No clinically concerning trends were seen in gastric biopsy results. Endocrine cell hyperplasia, dysplasia and neoplasia were not observed.

CONCLUSION

Dexlansoprazole MR 30-90 mg has a safety profile comparable to that of lansoprazole.

Role of hepcidin in murine brain iron metabolism

Brain iron homeostasis is maintained by a balance of both iron uptake and release, and accumulating evidence has revealed that brain iron concentrations increase with aging. Hepcidin, an iron regulatory hormone produced by hepatocytes in response to inflammatory stimuli, iron, and hypoxia, has been shown to be the long-sought hormone responsible for the regulation of body iron balance and recycling in mammals. In this study, we report that hepcidin is widely expressed in the murine brain. In cerebral cortex, hippocampus and striatum, hepcidin mRNA levels increased with aging. Injection of hepcidin into the lateral cerebral ventricle resulted in decreased Fpn1 protein levels in cerebral cortex, hippocampus, and striatum. Additionally, treatment of primary cultured neurons with hepcidin caused decreased neuronal iron release and Fpn1 protein levels. Together, our data provide further evidence that hepcidin may be involved in the regulation of brain iron metabolism.

Heat-induced protein structure and subfractions in relation to protein degradation kinetics and intestinal availability in dairy cattle

The objectives of this study were to reveal protein structures of feed tissues affected by heat processing at a cellular level, using the synchrotron-based Fourier transform infrared microspectroscopy as a novel approach, and quantify protein structure in relation to protein digestive kinetics and nutritive value in the rumen and intestine in dairy cattle. The parameters assessed included 1) protein structure alpha-helix to beta-sheet ratio; 2) protein subfractions profiles; 3) protein degradation kinetics and effective degradability; 4) predicted nutrient supply using the intestinally absorbed protein supply (DVE)/degraded protein balance (OEB) system for dairy cattle. In this study, Vimy flaxseed protein was used as a model feed protein and was autoclave-heated at 120 degrees C for 20, 40, and 60 min in treatments T1, T2, and T3, respectively. The results showed that using the synchrotron-based Fourier transform infrared microspectroscopy revealed and identified the heat-induced protein structure changes. Heating at 120 degrees C for 40 and 60 min increased the protein structure alpha-helix to beta-sheet ratio. There were linear effects of heating time on the ratio. The heating also changed chemical profiles, which showed soluble CP decreased upon heating with concomitant increases in nonprotein nitrogen, neutral, and acid detergent insoluble nitrogen. The protein subfractions with the greatest changes were PB1, which showed a dramatic reduction, and PB2, which showed a dramatic increase, demonstrating a decrease in overall protein degradability. In situ results showed a reduction in rumen-degradable protein and in rumen-degradable dry matter without differences between the treatments. Intestinal digestibility, determined using a 3-step in vitro procedure, showed no changes to rumen undegradable protein. Modeling results showed that heating increased total intestinally absorbable protein (feed DVE value) and decreased degraded protein balance (feed OEB value), but there were no differences between the treatments. There was a linear effect of heating time on the DVE and a cubic effect on the OEB value. Our results showed that heating changed chemical profiles, protein structure alpha-helix to beta-sheet ratio, and protein subfractions; decreased rumen-degradable protein and rumen-degradable dry matter; and increased potential nutrient supply to dairy cattle. The protein structure alpha-helix to beta-sheet ratio had a significant positive correlation with total intestinally absorbed protein supply and negative correlation with degraded protein balance.