Phase transition and dielectric properties of BaTiO3 ceramics containing 10 mol% BaGeO3

Dielectric properties and the cubic ? tetragonal phase transition temperature of dense BaTiO₃ ceramics containing 10 mol% BaGeO₃, sintered between 840 and 1350 °C, have been investigated. The ceramic bodies were prepared from a nano-sized BaTi_0.9/Ge_0.1O₃ powder consisting of both BaTiO₃ and BaGeO₃ phases. The addition of BaGeO₃ leads to a reduction and broadening of the permittivity maximum, and to a small downshift of the paraelectric ? ferroelectric phase transition temperature, compared to a pure BaTiO₃ ceramic. Lower sintering temperatures and thus small grain sizes of the ceramics cause an additional reduction of the maximum permittivity down to 2800. Both DTA and dilatometric measurements reveal also a downshifting of the phase transition temperature, as well as a decrease of the latent heat.     

CD146 Delineates an Interfascicular Cell Sub-Population in Tendon That Is Recruited during Injury through Its Ligand Laminin-α4

The interfascicular matrix (IFM) binds tendon fascicles and contains a population of morphologically distinct cells. However, the role of IFM-localised cell populations in tendon repair remains to be determined. The basement membrane protein laminin-α4 also localises to the IFM. Laminin-α4 is a ligand for several cell surface receptors, including CD146, a marker of pericyte and progenitor cells. We used a needle injury model in the rat Achilles tendon to test the hypothesis that the IFM is a niche for CD146+ cells that are mobilised in response to tendon damage. We also aimed to establish how expression patterns of circulating non-coding RNAs alter with tendon injury and identify potential RNA-based markers of tendon disease. The results demonstrate the formation of a focal lesion at the injury site, which increased in size and cellularity for up to 21 days post injury. In healthy tendon, CD146+ cells localised to the IFM, compared with injury, where CD146+ cells migrated towards the lesion at days 4 and 7, and populated the lesion 21 days post injury. This was accompanied by increased laminin-α4, suggesting that laminin-α4 facilitates CD146+ cell recruitment at injury sites. We also identified a panel of circulating microRNAs that are dysregulated with tendon injury. We propose that the IFM cell niche mediates the intrinsic response to injury, whereby an injury stimulus induces CD146+ cell migration. Further work is required to fully characterise CD146+ subpopulations within the IFM and establish their precise roles during tendon healing.     

Optical properties and appearance characteristics of tomato fruit (Lycopersicon esculentum)

Characterisation of the optical properties of the internal structures of tomatoes enhances assessment of the composite appearance. Reflectance colorimetry and the Kubelka-Munk analysis to distinguish three distinct maturity groups of tomatoes were tested. Differences in the scatter, absorption and internal transmittance were found amongst the component structures of the intact tomato. Tomato fruit was also pulped and a range of dilutions prepared. The decrease in scatter, absorption and increase in internal transmittance with increased dilution suggests the importance of optical properties with changes in concentration.     

Peritraumatic dissociation and experiential avoidance as prospective predictors of posttraumatic stress symptoms.

Peritraumatic dissociation (PD) and experiential avoidance (EA) have been implicated in the etiology of posttraumatic stress symptomatology (PTSS); however, the function of these two factors in the onset and maintenance of PTSS following a potentially traumatic event is unclear. The temporal relationships between EA, PD, and the four clusters of PTSS proposed by the Simms/Watson dysphoria model (Simms, Watson, & Doebbeling, 2002) were examined in a three-wave prospective investigation of 532 undergraduate women participating in an ongoing longitudinal study at the time of a campus shooting. Path analyses indicated that preshooting EA predicted greater PD, intrusions, and dysphoria symptoms approximately one month postshooting. PD was associated with increased symptomatology across all four clusters 1-month postshooting, while 1-month postshooting EA was associated with higher dysphoria and hyperarousal symptoms eight months postshooting. PD had a significant indirect effect on all four PTSS clusters eight months postshooting via 1-month postshooting symptom reports. The results suggest that both EA and PD show unique influences as risk factors for PTSS following a potentially traumatic event. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Spectra and lifetimes of fluorescence resonance energy transfer fluorophores under two-photon excitation

We show two-photon spectra and lifetimes acquired using conventional confocal microscopes equipped with an ultra-short pulsed laser and a time-gated intensified charge coupled device. We report on the two-photon spectra and lifetimes of Alexa350, enhanced green fluorescent protein (EGFP), EGFP-CD46, and Cy3 labelled antibodies. Cellular and extracellular EGFP two-photon spectra and lifetimes are compared.     

Estimate of oil persisting on the beaches of Prince William Sound 12 years after the Exxon Valdez oil spill

We estimated the amount of oil remaining in Prince William Sound, Alaska, 12 yr after the 1989 Exxon Valdez spill to assess its importance as a long-term reservoir of toxic hydrocarbons. We found oil on 78 of 91 beaches randomly selected according to their oiling history. Surface oiling was recorded for randomly placed quadrats, which were then excavated and examined for subsurface oil. The cumulative area of beach contaminated by surface or subsurface oil was estimated at 11.3 ha. Surface oil varied little with tide height, but subsurface oil was more prevalent at the middle tide heights. The mass of remaining subsurface oil is conservatively estimated at 55 600 kg. Analysis of terpanes indicated that over 90% of the surface oil and all of the subsurface oil was from the Exxon Valdez and that Monterey Formation oil deposited after the 1964 Alaska earthquake accounted for the remaining surface oil. These results indicate that oil from the Exxon Valdez remains by far the largest reservoir of biologically available polycyclic aromatic hydrocarbons on beaches impacted by the spill and that biota dependent on these beaches risk continued exposure.     

The influence of BaGeO3 on the properties of Ba(Ti1?xSnx)O3 ceramics on the basis of sol-gel powders

Ba(Ti_1−x−y Sn _x Ge _y )O₃ (BTSG-x-y; x = 0, 0.05; y = 0–0.05) powders were synthesized by a sol-gel (SG) method and for comparative purposes also by a mixed-oxide (MO) method. In this system, BaGeO₃ functions as sintering additive. Due to smaller particle sizes of the SG powders a higher sintering activity was found, which resulted in reduced grain growth and in a more homogenous grain size distribution for the corresponding ceramics. The dependence on the paraelectric ⇆ ferroelectric phase transition, i.e. the phase transition temperature, the width of the transition region and completeness were examined by dielectric measurements, DTA as well as by SEM, EDX and XRD investigations with respect to the BaGeO₃ content, synthesis method and sintering temperature. The phase transition temperatures of the SG ceramics are remarkably higher than those of the MO ceramics with the same nominal compositions. The reason is a lower tin concentration within the grains of SG ceramics as confirmed by EDX and XRD investigations. The presence of BaGeO₃ in barium titanate–stannate system on the basis of a SG method caused an improved incorporation of tin in the BaTiO₃ lattice.     

Identifying Novel Osteoarthritis-Associated Genes in Human Cartilage Using a Systematic Meta-Analysis and a Multi-Source Integrated Network

Osteoarthritis, the most common joint disorder, is characterised by deterioration of the articular cartilage. Many studies have identified potential therapeutic targets, yet no effective treatment has been determined. The aim of this study was to identify and rank osteoarthritis-associated genes and micro-RNAs to prioritise those most integral to the disease. A systematic meta-analysis of differentially expressed mRNA and micro-RNAs in human osteoarthritic cartilage was conducted. Ingenuity pathway analysis identified cellular senescence as an enriched pathway, confirmed by a significant overlap (p < 0.01) with cellular senescence drivers (CellAge Database). A co-expression network was built using genes from the meta-analysis as seed nodes and combined with micro-RNA targets and SNP datasets to construct a multi-source information network. This accumulated and connected 1689 genes which were ranked based on node and edge aggregated scores. These bioinformatic analyses were confirmed at the protein level by mass spectrometry of the different zones of human osteoarthritic cartilage (superficial, middle, and deep) compared to normal controls. This analysis, and subsequent experimental confirmation, revealed five novel osteoarthritis-associated proteins (PPIB, ASS1, LHDB, TPI1, and ARPC4-TTLL3). Focusing future studies on these novel targets may lead to new therapies for osteoarthritis.     

Synthesis and sintering of nano-sized BaSnO<Subscript>3</Subscript> powders containing BaGeO<Subscript>3</Subscript>

The formation of solid solutions of the type [Ba(HOC₂H₄OH)₄][Sn_1−x Ge _x (OC₂H₄O)₃] as BaSn_1−x /Ge _x O₃ precursor and the phase evolution during its thermal decomposition are described in this paper. The 1,2-ethanediolato complexes can be decomposed to nano-sized BaSn_1−x /Ge _x O₃ preceramic powders. Samples with x = 0.05 consist of only a Ba(Sn,Ge)O₃ phase, whereas powders with x = 0.15 and 0.25 show diffraction patterns of both the Ba(Sn,Ge)O₃ and BaGeO₃ phase. The sintering behaviour was investigated on powders with a BaGeO₃ content of 5 and 15 mol%. These powders show a specific surface area of 15.4–15.9 m²/g and were obtained from calcination above 800 °C. The addition of BaGeO₃ reduced the sintering temperature of the ceramics drastically. BaSn_0.95Ge_0.05O₃ ceramics with a relative density of at least 90% can be obtained by sintering at 1150 °C for 1 h. The ceramic bodies reveal a fine microstructure with cubical-shaped grains between 0.25 and 0.6 μm. For dense ceramics, the sintering temperature could be reduced down to 1090 °C, when the soaking time was extended up to 10 h.     

Liquid phase assisted densification of superhard B6O materials

B₆O-based materials are known as some of the hardest materials after diamond and cubic boron nitride with a hardness of 45 GPa measured on single crystals. Several attempts were made to produce B₆O materials by hot pressing, but without success. Based on thermodynamic considerations the possibility of the use of sintering additives was discussed and the developed concepts were validated by densification of the materials using FAST (field assisted sintering technique)/SPS methods and analysing the microstructure and properties of the resulting materials. Two groups of materials were found to be suitable for the densification: transition metals which form borides with B₆O, the elements of the first to fourth main groups of the periodic table and the rare earths (Sc, Y, and lanthanides) which are in equilibrium in the oxide form with B₆O and form a liquid phase during densification at 1700–1900 °C. Superhard dense B₆O materials were produced and their properties investigated.