Electromechanical and biological evaluations of 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 as a lead-free piezoceramic for implantable bioelectronics

Smart implantable electronic medical devices are being developed to deliver healthcare that is more connected, personalised, and precise. Many of these implantables rely on piezoceramics for sensing, communication, energy autonomy, and biological stimulation, but the piezoceramics with the strongest piezoelectric coefficients are almost exclusively lead-based. In this article, we evaluate the electromechanical and biological characteristics of a lead-free alternative, 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 (BNT-6BT), manufactured via two synthesis routes: the conventional solid-state method (PIC700) and tape casting (TC-BNT-6BT). The BNT-6BT materials exhibited soft piezoelectric properties, with d33 piezoelectric coefficients that were inferior to commonly used PZT (PIC700: 116 pC/N; TC-BNT-6BT: 121 pC/N; PZT-5A: 400 pC/N). The material may be viable as a lead-free substitute for soft PZT where moderate performance losses up to 10 dB are tolerable, such as pressure sensing and pulse-echo measurement. No short-term harmful biological effects of BNT-6BT were detected and the material was conducive to the proliferation of MC3T3-E1 murine preosteoblasts. BNT-6BT could therefore be a viable material for electroactive implants and implantable electronics without the need for hermetic sealing

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Nordic Seas polynyas and their role in preconditioning marine productivity during the Last Glacial Maximum.

Arctic and Antarctic polynyas are crucial sites for deep-water formation, which helps sustain global ocean circulation. During glacial times, the occurrence of polynyas proximal to expansive ice sheets in both hemispheres has been proposed to explain limited ocean ventilation and a habitat requirement for marine and higher-trophic terrestrial fauna. Nonetheless, their existence remains equivocal, not least due to the hitherto paucity of sufficiently characteristic proxy data. Here we demonstrate polynya formation in front of the NW Eurasian ice sheets during the Last Glacial Maximum (LGM), which resulted from katabatic winds blowing seaward of the ice shelves and upwelling of warm, sub-surface Atlantic water. These polynyas sustained ice-sheet build-up, ocean ventilation, and marine productivity in an otherwise glacial Arctic desert. Following the catastrophic meltwater discharge from the collapsing ice sheets at ~17.5 ka BP, polynya formation ceased, marine productivity declined dramatically, and sea ice expanded rapidly to cover the entire Nordic Seas

Effects of tetradecylthioacetic acid (TTA) treatment on lipid metabolism in salmon hearts—in vitro and in vivo studies

acceptedVersio

Sudden increased mortality in large seemingly healthy farmed Atlantic salmon (Salmo salar L.) was associated with environmental and dietary changes

publishedVersio

Genome wide response to dietary tetradecylthioacetic acid supplementation in the heart of Atlantic Salmon (<it>Salmo salar</it> L)

Abstract Background Under-dimensioned hearts causing functional problems are associated with higher mortality rates in intensive Atlantic salmon aquaculture. Previous studies have indicated that tetradecylthioacetic acid (TTA) induces cardiac growth and also stimulates transcription of peroxisome proliferator activated receptors (PPAR) αand βin the Atlantic salmon heart. Since cardiac and transcriptional responses to feed are of high interest in aquaculture, the objective of this study was to characterize the transcriptional mechanisms induced by TTA in the heart of Atlantic salmon. Results Atlantic salmon were kept at sea for 17 weeks. During the first 8 weeks the fish received a TTA supplemented diet. Using microarrays, profound transcriptional effects were observed in the heart at the end of the experiment, 9 weeks after the feeding of TTA stopped. Approximately 90% of the significant genes were expressed higher in the TTA group. Hypergeometric testing revealed the over-representation of 35 gene ontology terms in the TTA fed group. The GO terms were generally categorized into cardiac performance, lipid catabolism, glycolysis and TCA cycle. Conclusions Our results indicate that TTA has profound effects on cardiac performance based on results from microarray and qRT-PCR analysis. The gene expression profile favors a scenario of ”physiological”lright hypertrophy recognized by increased oxidative fatty acid metabolism, glycolysis and TCA cycle activity as well as cardiac growth and contractility in the heart ventricle. Increased cardiac efficiency may offer significant benefits in the demanding Aquaculture situations.</p

Ages and geochemical and geophysical characteristics of sediment core MD99-2294, Lofoten Contourite Drift

A sediment core from the Lofoten Contourite Drift on the continental slope off Northern Norway, proximal to the former Vestfjorden-Trsnadjupet Ice Stream, details the development, variability and decline of marine margins of the northwestern Fennoscandian Ice Sheet during the time interval 25.3-14 cal ka BP, including the Last Glacial Maximum and onset of the deglaciation based on high-resolution IRD records. From the core interval between 25.3 and 17.7 cal ka BP we report data points with a mean time step of 10 years, between 17.7 cal ka BP and the Holocene time steps are typically 50 years. The core is divided into 7 informal ice-rafted debris (IRD) zones based on the variations in IRD including 7 major IRD maxima (A-G), inferred to represent periods of high iceberg production. Petrological identification reveals dominance of crystalline IRD (monocrystalline, plutonic and metamorphic rock fragments) accounting for 75-80% of total IRD assemblages, while sedimentary fragments generally account for 15-20%. The crystalline fragments (including eclogite and mangerite from a nearby terrestrial source) increase across the IRD peaks while the sedimentary fragments remain constant. This points to the importance of erosional products from icebergs originating from fast-flowing paleo-ice streams including the Vestfjorden-Trsnadjupet Ice Stream draining from the Fennoscandian mainland during the IRD maxima periods. Increased temperature of the adjacent surface water masses was probably an important external forcing factor on the Fennoscandian Ice Sheet behavior because some IRD maxima and plumite deposition from meltwater plumes post-date periods of increased sea surface temperatures. The peak IRD depositions occur in centennial and millennial time cycles (~200, 1030 and 3900 year) indicating some external forcing by solar variation. Both mechanisms could explain the observed synchronous instability of the northwestern Fennoscandian Ice Sheet to other European Ice Sheets