Micro-saw devices based on randomly-oriented PZT films: Design, fabrication and characterization

The main objective of this work was to research and develop a sensor device to monitor gas leakage in cryogenic temperatures and high vacuum. In addition, the sensor device should be small in size, function with low power, and display a short recovery time. The end application for this technology would be to monitor fuel leaks of hydrazine when refueling space satellites. To meet the specified requirements, an acoustic wave device was studied in this work. A micro-surface acoustic wave (muSAW) device was fabricated through a multi-layer thin film technique, where the active sensing material is based on a 300 nm thick PbZr0.52Tii0.48O3 (PZT) piezoelectric film grown via a sol-gel process. The electrodes were based on Si/SiO2/TiOx/Pt and Si/SiO 2/TiOx multi-layered structures and were fabricated by thermal oxidation and sputtering techniques. Improved deposition and crystallization methods for the PZT film were developed in this work which resulted in crack- and porous-free texturized and randomly-oriented PZT films. The phase, chemistry and microstructure of the PZT films were determined by X-ray diffraction (XRD), Energy Dispersive X-Ray Analysis (EDX), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. The surface energy of the films was measured by means of a static sessile drop method. The ferroelectric and electrical characterization of the film was completed longitudinally by measuring the polarization-voltage (P-V), capacitance-voltage (C-V) and current-voltage (I-V) curves. The propagation wave velocity for the multi-layered structure was approximated using an electromechanical equivalent model and the results were used to design the interdigitated transducers (IDTs) for the SAW devices. IDTs were later deposited over the PZT via photolithography process. Finally, the electro-acoustic frequency response in |S21| mode was measured using a vector network analyzer (VNA) and Rayleigh mode SAW and non-Rayleigh mode SAW responses were observed

Influencia de la adición de CuO sobre las propiedades dieléctricas y piezoeléctricas de cerámicos

Con el objetivo de evaluar la influencia del Cu sobre las propiedades dieléctricas y piezoeléctricas del K1/2Na1/2NbO3 (KNN) se sintetizó, por reacción en estado sólido, KNN dopado con diferentes concentraciones de CuO (0 a 2% mol). El análisis del material se realizó empleando mediciones de densidad por el método de Arquímedes, difracción de rayos X (DRX), espectroscopía Raman, microscopía electrónica de barrido (SEM), curvas de polarización, constante piezoeléctrica (d33) y espectroscopía de impedancia a temperatura ambiente. En general, se observó que el aditivo no logró mejorar las propiedades dieléctricas o piezoeléctricas. Pequeñas cantidades de CuO (0,5%mol) afectaron ligeramente el proceso de densificación, mientras que altas concentraciones incrementaron la porosidad. Asimismo, bajas concentraciones de CuO redujeron drásticamente los valores de d33, presumiblemente debido al efecto endurecedor del aditivo.In this paper the influence of Cu on dielectric and piezoelectric properties of K1/2Na1/2NbO3 (KNN) was evaluated. Samples were obtained by solid state reaction doping with CuO (0 to 2 mol%). The obtained samples were characterized by the Archimedes method, X-Ray diffraction, Raman spectroscopy, Scanning Electron Microscopy, polarization curves, piezoelectric constant (d33) and impedance spectroscopy at room temperature. In general, it was observed that doping does not improve dielectric and piezoelectric properties. Small amounts of CuO (0.5 mol%) slightly affected the densification process, while high concentrations increased the porosity of the samples. Also, low concentrations of CuO drastically reduced d33 values, presumably due to the hardening effect of the additive.Fil: Ramajo, Leandro Alfredo. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Mar del Plata. Instituto de Inv.en Ciencia y Tecnol.materiales (i); Argentina;Fil: Taub, Jonathan. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Mar del Plata. Instituto de Inv.en Ciencia y Tecnol.materiales (i), Argentina;Fil: Castro, Miriam Susana. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Mar del Plata. Instituto de Inv.en Ciencia y Tecnol.materiales (i); Argentina

Lead free piezoelectric ceramics based on Bi0.5(Na0.8K0.2)0.5TiO3 y K0.5Na0.5NbO3 systems

Los materiales cerámicos basados en circonato-titanato de plomo, Pb(Zr,Ti)O3(PZT), son muy conocidos por sus excelentes propiedades piezoeléctricas. Si bien, estos materiales se producen generalmente a partir de la técnica de mezcla de óxidos, la cual es relativamente simple y económica, en su formulación se emplea un alto contenido de óxido de plomo (aprox. 70%). Dado que el plomo y sus compuestos son considerados tóxicos y peligrosos, no sólo por la polución directa que genera el proceso de manufactura y maquinado de los compuestos, sino también porque los productos que contienen PZT no pueden ser reciclados, recientemente se han comenzado a investigar diferentes composiciones piezoeléctricas para su reemplazo. En este trabajo, se analizan algunos desarrollos propios en el campo de los materiales piezoeléctricos libres de plomo donde se enfatiza la correlación existente entre las propiedades finales, la microestructura desarrollada y la estructura estabilizada.Ceramics based on lead zirconium titanate Pb(Zr,Ti)O3 (PZT) are well known for their excellent piezoelectric properties. These materials are generally produced by solid reaction technique, which is relatively simple and economical; however their production needs high lead oxide content (approx. 70%). Lead and its compounds are considered toxic and dangerous, due to direct pollution generated by the manufacturing process and machining of the compounds, and the inability to recycle products containing PZT. Therefore, other piezoelectric compositions based on lead free materials have begun investigated. In this paper, some developments in the field of lead-free piezoelectric materials, correlating the structure and microstructure with the properties materials properties are analyzed.Fil: Castro, Miriam Susana. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); ArgentinaFil: Camargo, Javier Eduardo. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); ArgentinaFil: Taub, Jonathan. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); ArgentinaFil: Fernandez, J. F.. Instituto de Ceramica y Vidrio de Madrid; EspañaFil: Rubio-Marcos, F.. Instituto de Ceramica y Vidrio de Madrid; EspañaFil: Ramajo, Leandro Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentin

Equation of State in Relativistic Magnetohydrodynamics: variable versus constant adiabatic index

The role of the equation of state for a perfectly conducting, relativistic magnetized fluid is the main subject of this work. The ideal constant $\Gamma$-law equation of state, commonly adopted in a wide range of astrophysical applications, is compared with a more realistic equation of state that better approximates the single-specie relativistic gas. The paper focus on three different topics. First, the influence of a more realistic equation of state on the propagation of fast magneto-sonic shocks is investigated. This calls into question the validity of the constant $\Gamma$-law equation of state in problems where the temperature of the gas substantially changes across hydromagnetic waves. Second, we present a new inversion scheme to recover primitive variables (such as rest-mass density and pressure) from conservative ones that allows for a general equation of state and avoids catastrophic numerical cancellations in the non-relativistic and ultrarelativistic limits. Finally, selected numerical tests of astrophysical relevance (including magnetized accretion flows around Kerr black holes) are compared using different equations of state. Our main conclusion is that the choice of a realistic equation of state can considerably bear upon the solution when transitions from cold to hot gas (or viceversa) are present. Under these circumstances, a polytropic equation of state can significantly endanger the solution.Comment: 14 pages, 14 figure

BMP-12 Treatment of Adult Mesenchymal Stem Cells In Vitro Augments Tendon-Like Tissue Formation and Defect Repair In Vivo

We characterized the differentiation of rat bone marrow-derived mesenchymal stem cells (BM-MSCs) into tenocyte-like cells in response to bone morphogenetic protein-12 (BMP-12). BM-MSCs were prepared from Sprague-Dawley rats and cultured as monolayers. Recombinant BMP-12 treatment (10 ng/ml) of BM-MSCs for 12 hours in vitro markedly increased expression of the tenocyte lineage markers scleraxis (Scx) and tenomodulin (Tnmd) over 14 days. Treatment with BMP-12 for a further 12-hour period had no additional effect. Colony formation assays revealed that ∼80% of treated cells and their progeny were Scx- and Tnmd-positive. BM-MSCs seeded in collagen scaffolds and similarly treated with a single dose of BMP-12 also expressed high levels of Scx and Tnmd, as well as type I collagen and tenascin-c. Furthermore, when the treated BM-MSC-seeded scaffolds were implanted into surgically created tendon defects in vivo, robust formation of tendon-like tissue was observed after 21 days as evidenced by increased cell number, elongation and alignment along the tensile axis, greater matrix deposition and the elevated expression of tendon markers. These results indicate that brief stimulation with BMP-12 in vitro is sufficient to induce BM-MSC differentiation into tenocytes, and that this phenotype is sustained in vivo. This strategy of pretreating BM-MSCs with BMP-12 prior to in vivo transplantation may be useful in MSC-based tendon reconstruction or tissue engineering

Transcriptome Analysis of Mouse Stem Cells and Early Embryos

Understanding and harnessing cellular potency are fundamental in biology and are also critical to the future therapeutic use of stem cells. Transcriptome analysis of these pluripotent cells is a first step towards such goals. Starting with sources that include oocytes, blastocysts, and embryonic and adult stem cells, we obtained 249,200 high-quality EST sequences and clustered them with public sequences to produce an index of approximately 30,000 total mouse genes that includes 977 previously unidentified genes. Analysis of gene expression levels by EST frequency identifies genes that characterize preimplantation embryos, embryonic stem cells, and adult stem cells, thus providing potential markers as well as clues to the functional features of these cells. Principal component analysis identified a set of 88 genes whose average expression levels decrease from oocytes to blastocysts, stem cells, postimplantation embryos, and finally to newborn tissues. This can be a first step towards a possible definition of a molecular scale of cellular potency. The sequences and cDNA clones recovered in this work provide a comprehensive resource for genes functioning in early mouse embryos and stem cells. The nonrestricted community access to the resource can accelerate a wide range of research, particularly in reproductive and regenerative medicine

Broad-Spectrum Matrix Metalloproteinase Inhibition Curbs Inflammation and Liver Injury but Aggravates Experimental Liver Fibrosis in Mice

Background Liver fibrosis is characterized by excessive synthesis of extracellular matrix proteins, which prevails over their enzymatic degradation, primarily by matrix metalloproteinases (MMPs). The effect of pharmacological MMP inhibition on fibrogenesis, however, is largely unexplored. Inflammation is considered a prerequisite and important co-contributor to fibrosis and is, in part, mediated by tumor necrosis factor (TNF)-α-converting enzyme (TACE). We hypothesized that treatment with a broad-spectrum MMP and TACE-inhibitor (Marimastat) would ameliorate injury and inflammation, leading to decreased fibrogenesis during repeated hepatotoxin-induced liver injury.Methodology/Principal Findings Liver fibrosis was induced in mice by repeated carbon tetrachloride (CCl4) administration, during which the mice received either Marimastat or vehicle twice daily. A single dose of CCl4was administered to investigate acute liver injury in mice pretreated with Marimastat, mice deficient in Mmp9, or mice deficient in both TNF-α receptors. Liver injury was quantified by alanine aminotransferase (ALT) levels and confirmed by histology. Hepatic collagen was determined as hydroxyproline, and expression of fibrogenesis and fibrolysis-related transcripts was determined by quantitative reverse-transcription polymerase chain reaction. Marimastat-treated animals demonstrated significantly attenuated liver injury and inflammation but a 25% increase in collagen deposition. Transcripts related to fibrogenesis were significantly less upregulated compared to vehicle-treated animals, while MMP expression and activity analysis revealed efficient pharmacologic MMP-inhibition and decreased fibrolysis following Marimastat treatment. Marimastat pre-treatment significantly attenuated liver injury following acute CCl4-administration, whereas Mmp9 deficient animals demonstrated no protection. Mice deficient in both TNF-α receptors exhibited an 80% reduction of serum ALT, confirming the hepatoprotective effects of Marimastat via the TNF-signaling pathway.Conclusions/Significance Inhibition of MMP and TACE activity with Marimastat during chronic CCl4administration counterbalanced any beneficial anti-inflammatory effect, resulting in a positive balance of collagen deposition. Since effective inhibition of MMPs accelerates fibrosis progression, MMP inhibitors should be used with caution in patients with chronic liver diseases

Do serum biomarkers really measure breast cancer?

Background Because screening mammography for breast cancer is less effective for premenopausal women, we investigated the feasibility of a diagnostic blood test using serum proteins. Methods This study used a set of 98 serum proteins and chose diagnostically relevant subsets via various feature-selection techniques. Because of significant noise in the data set, we applied iterated Bayesian model averaging to account for model selection uncertainty and to improve generalization performance. We assessed generalization performance using leave-one-out cross-validation (LOOCV) and receiver operating characteristic (ROC) curve analysis. Results The classifiers were able to distinguish normal tissue from breast cancer with a classification performance of AUC = 0.82 ± 0.04 with the proteins MIF, MMP-9, and MPO. The classifiers distinguished normal tissue from benign lesions similarly at AUC = 0.80 ± 0.05. However, the serum proteins of benign and malignant lesions were indistinguishable (AUC = 0.55 ± 0.06). The classification tasks of normal vs. cancer and normal vs. benign selected the same top feature: MIF, which suggests that the biomarkers indicated inflammatory response rather than cancer. Conclusion Overall, the selected serum proteins showed moderate ability for detecting lesions. However, they are probably more indicative of secondary effects such as inflammation rather than specific for malignancy.United States. Dept. of Defense. Breast Cancer Research Program (Grant No. W81XWH-05-1-0292)National Institutes of Health (U.S.) (R01 CA-112437-01)National Institutes of Health (U.S.) (NIH CA 84955

Genetic overlap between autoimmune diseases and non-Hodgkin lymphoma subtypes

Epidemiologic studies show an increased risk of non-Hodgkin lymphoma (NHL) in patients with autoimmune disease (AD), due to a combination of shared environmental factors and/or genetic factors, or a causative cascade: chronic inflammation/antigen-stimulation in one disease leads to another. Here we assess shared genetic risk in genome-wide-association-studies (GWAS). Secondary analysis of GWAS of NHL subtypes (chronic lymphocytic leukemia, diffuse large B-cell lymphoma, follicular lymphoma, and marginal zone lymphoma) and ADs (rheumatoid arthritis, systemic lupus erythematosus, and multiple sclerosis). Shared genetic risk was assessed by (a) description of regional genetic of overlap, (b) polygenic risk score (PRS), (c)"diseasome", (d)meta-analysis. Descriptive analysis revealed few shared genetic factors between each AD and each NHL subtype. The PRS of ADs were not increased in NHL patients (nor vice versa). In the diseasome, NHLs shared more genetic etiology with ADs than solid cancers (p = .0041). A meta-analysis (combing AD with NHL) implicated genes of apoptosis and telomere length. This GWAS-based analysis four NHL subtypes and three ADs revealed few weakly-associated shared loci, explaining little total risk. This suggests common genetic variation, as assessed by GWAS in these sample sizes, may not be the primary explanation for the link between these ADs and NHLs