High TF Research Articles

Cooling history of a wet-granulated blast furnace slag (GBS)

Granulated blast furnace slag (GBS) is a glassy by-product of the steel industry that is formed during quenching of the molten slag after the blast furnace in a water-jet. To elucidate the cooling history of GBS, calorimetric scanning in the glass transition range and viscometric experiments at temperatures above the liquidus were performed. The GBS studied was of industrial origin with a d50 = 700 μm and > 99% glassy. It is found that GBS glass is of high potential energy, showing a fictive temperature that is approx. 160 K higher than the glass transition temperature under standard cooling conditions. Using different viscosity models and the relationship between quench rate and shear viscosity at the fictive temperature it is calculated that GBS was formed at a cooling rate of approx. 2.6 × 105 K s−1 corresponding to a shear viscosity of 105.9 Pa s. Due to the high Tf and high amount of heat that is released during structural relaxation, GBS is assigned to the class of hyperquenched glasses.

Effect of Fermentation Conditions and Plucking Standards of Tea Leaves on the Chemical Components and Sensory Quality of Fermented Juice

The effects of fermentation conditions (temperature, time, and pH) and plucking standards (one leaf and a bud to four leaves and a bud) on the chemical components and sensory quality of the fermented juices processed from crushed fresh tea leaves were investigated. The results showed that optimum fermentation conditions that resulted in fermented juices of the best sensory quality and the highest content of TFs were a temperature of 35°C, time duration of 75 min, and pH 5.1. The fermented juices processed from new shoots with three leaves and a bud or four leaves and a bud afforded high overall acceptability and TF concentration. These differences arise because tea leaves with different plucking standards have different catechin content and enzyme activities. Fermented tea juice possessed higher concentrations of chemical components such as soluble solids, amino acids, and TFs and exhibited better sensory quality as compared to black tea infusion. The TF concentrations decreased as the pH of the fermenting juice increased, and the fermented juice showed the best overall acceptability. These results provide essential information for the improvement of the processing of black tea beverage by suggesting fermentation of fresh tea leaves as a better alternative to their infusion.

Role of CoFeB thickness in electric field controlled sub-100 nm sized magnetic tunnel junctions

We report a comprehensive study on the role of the free layer thickness (tF) in electric-field controlled nanoscale perpendicular magnetic tunnel junctions (MTJs), comprising of free layer structure Ta/Co40Fe40B20/MgO, by using dc magnetoresistance and ultra-short magnetization switching measurements. Focusing on MTJs that exhibits positive effective device anisotropy (Keff), we observe that both the voltage-controlled magnetic anisotropy (ξ) and voltage modulation of coercivity show strong dependence on tF. We found that ξ varies dramatically and unexpectedly from ∼−3 fJ/V-m to ∼−41 fJ/V-m with increasing tF. We discuss the possibilities of electric-field tuning of the effective surface anisotropy term, KS as well as an additional interfacial magnetoelastic anisotropy term, K3 that scales with 1/tF2. Voltage pulse induced 180° magnetization reversal is also demonstrated in our MTJs. Unipolar switching and oscillatory function of switching probability vs. pulse duration can be observed at higher tF, and agrees well with the two key device parameters — Keff and ξ.

Impact of fiberizing method on physical properties of glass wool fibers

The physical properties of the glass fibers and their woven and non-woven products are affected by many factors, such as glass composition, thermal history, melting conditions, and fiberizing method. In this work, we have investigated the impact of fiberizing method on dynamic properties and relaxation behavior of the glass wool fibers, and inferred its effect on the mechanical properties of the filtration mats consisting of glass wool fibers. We have fabricated the glass wool fibers using the rotary (R) and flame (F) attenuation processes, which are denominated as R- and F- fibers, respectively. Both fibers have the same chemical composition and hence similar structural features, surface quality, glass transition temperature (Tg), and sub-Tg enthalpy relaxation behaviors. However, two fibers show striking differences in the surface hydroxyl (OH) content, fictive temperature (Tf) and cooling rate (qc). F-fibers have weakly hydrogen-bonded surface hydroxy (OH) groups, while R-fibers have free OH groups and strongly hydrogen-bonded OH groups. F-fibers have higher Tf and qc than R-fibers. We argue that the higher tensile strength of the F-fiber mat (compared to the R-fiber mat) could be attributed to both the weaker hydrogen-bonded surface OH groups, and the higher Tf and qc values that may increase the tensile strength of fiber itself. This work gives guidance for designing the fiber mat products with high tensile strength.

Abstract 1815: Extracellular vesicles derived from lung cancer cell may contribute to the formation of malignant pleural effusion via activating Stat3/Tissue factor/VEGF

Abstract Malignant pleural effusion (MPE) is a poor prognostic sign for patients with non-small-cell lung cancer (NSCLC) and is noted around 15% at the time of initial diagnosis and 50% in their later courses. Previously, we have shown that IL-6/Stat3/tissue factor (TF)/VEGF pathway enhances lung cancer angiogenesis, metastasis and the generation of MPE. In the current study, we demonstrated that EVs derived from lung cancer cells may also contribute MPE formation. We first used ultra-filtration (UF) method as well as the classical ultra-centrifugation (UC) method to isolate EV from lung cancer cell line and demonstrated that the EVs isolated by UF method were characteristic with exosome marker in Western Blotting (Alix, CD63, and Tsg101), morphology at Transmission electron microscopy (TEM) and size in Nanosight system (30 to 150 nm). After labeling these EVs with the green fluorescent dye Cellvue, EVs uptake in AS2 cell can be imaged by the fluorescent microscopy. After the EV uptake of recipient cell, the oncogenic signal such as Stat3 and AKT were activated with increasing phosphorylation at Western blotting comparing to those adding serum free medium. Using the ELISA method, we found the cargos in these EV were enriched in IL6. We also found these cargo derived from EVs, containing high VEGF and TF, induced more prominent extravasation than serum free medium did in Miles assays. In clinical sample, we also isolated cancer cell from MPE and the purity of the cells was confirmed by immunofluorescent staining with specific TTF-1expression of lung adenocarcinoma. After short-term culture, EV from MPE cancer cell have the characteristic of exosome marker and induced more prominent extravasation than serum free medium as EV from AS2 cell did. And we also isolated EV direct from MPE and pleural effusion from congestive heart failure (CHF) patients. And we found EV derived from MPE induced more prominent extravasation than those derived from CHF in Miles assays. In conclusion, we demonstrated the UF is clinical assessable method for isolating EV from body fluid and EV derived from lung cancer cell and MPE may contribute oncogenic and angiogenic signal transmission accelerating the formation of MPE. Citation Format: Chien-Chung Lin, Wei-Lun Huang, Wu-Chou Su. Extracellular vesicles derived from lung cancer cell may contribute to the formation of malignant pleural effusion via activating Stat3/Tissue factor/VEGF [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1815. doi:10.1158/1538-7445.AM2017-1815

Is resistance futile? The role of activated thrombin‐activatable fibrinolysis inhibitor resistance in bleeding in factor XI deficiency

Is resistance futile? The role of activated thrombin‐activatable fibrinolysis inhibitor resistance in bleeding in factor XI deficiency

Abstract 3392: Lung cancer cell derived extracellular vesicles carrying DNAs, RNAs and proteins that may trigger oncogenic signals and promote angiogenesis

Abstract Extracellular vesicles (EVs) secreted from tumor cells have been implicated in modulating the tumor microenvironment changes. In this study, we demonstrated that EVs secreted by lung cancer cell are loaded with several cargos, such as DNA, RNA, cytokines, and growth factors. After the EVs had been taken up by recipient cells, the cargos might activate oncogenic pathways. We firstly isolated EVs from cell-free medium of lung cancer cells lines (AS2, PC9) and malignant pleural effusion (MPE) from patients with lung cancer. Isolated EVs were confirmed by the morphology and size in transmission electron microscopy (TEM) and the presentation of specific EV markers (Alix, CD63, and Tsg101). We found that several RNA species with enrichment of small RNAs and mutated EGFR DNA in the EVs of PC9 cells. After labeling with the green fluorescent dye Cellvue, the uptake of EVs by AS2 cells was imaged by the fluorescent microscopy. With these data, we further investigated the role of EVs in regulating the tumor microenvironment. We found the content of IL-6 in EVs, secreted from AS2 and CL1-5 cells, increased gradually after changing culture medium. And after uptake of EVs by recipient cells the cargos induced higher phsophorylation of Stat3 and AKT compared to the treatment with serum-free medium. Previously, we have shown that IL-6/Stat3/tissue factor (TF)/VEGF pathway enhances lung cancer angiogenesis, metastasis and the generation of MPE. In the current study, we demonstrated that EVs from lung cancer cells and in the MPE contain high level of VEGF and TF. And treatment with the EVs, containing high VEGF and TF, induced more prominent extravasation than cell free medium did in Miles assays. In conclusion, we successfully isolated EVs not only from culture supernatants but also from MPE of lung cancer patients. The EVs contain many biologically active molecules that may modulate behaviors of cancer cells and cells in tumor microenvironment. Citation Format: Chien-Chung Lin, Wei-Lun Huang, Wu-Chou Su. Lung cancer cell derived extracellular vesicles carrying DNAs, RNAs and proteins that may trigger oncogenic signals and promote angiogenesis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3392.

Viscozyme L treatment in the Oolong tea production processing

In this study, enzyme Viscozyme L treatment in Oolong tea process, we conducted Oolong tea production using the plant process (QTNM) with fermentation time of 18 hours and enzyme concentrations (QTCE) from 0% to 12% were added with 4 hours of fermentation. According to results from the analysis, we found that total polyphenol content and tannin content in QTCE decreased more quickly than those in QTNM. Total color and Total Dissolved Solid (TDS) in QTCE decreased more quickly than those in QTNM. Total color and Total Dissolved Solid (TDS) increased when enzyme concentration increased. We showed that there existed an empirical relation between ratio TF/TR and total color. The high TF: TR ratio reduced the total color and vice versa. The higher the TF:TR ratio was,the better the quality of Oolong tea was. This is a new direction in the research of applying enzyme in tea production in Vietnam

Recent temperature trends in the South Central Andes reconstructed from sedimentary chrysophyte stomatocysts in Laguna Escondida (1742 m a.s.l., 38°28 S, Chile)

In this study we present a quantitative, high resolution reconstruction of past austral winter length in the Chilean Andes at 38°S from AD 1920 to 2009. For Laguna Escondida, a nearly pristine lake situated on the flanks of the Andes at 1740m above sea level, past variability in the duration of the winter season (Days T4°C) was reconstructed. Because high elevation meteorological stations are absent in this region, the reconstruction provides novel insights into recent temperature trends in the central–southern Andes. As a cold-season temperature proxy, we used chrysophyte stomatocysts. This novel proxy for cold season temperature was so far applied successfully in the European Alps and Pyrenees but has not yet been tested in the Southern Hemisphere. The reconstruction in this study was based on a newly developed Transfer Function to estimate Days T4°C (number of consecutive days with surface water temperatures at or below 4°C) from sedimentary stomatocyst assemblages (R2boot=0.8, RMSEPboot=28.7days (=half the standard deviation)). To develop a high quality TF model, sediment traps and thermistors were placed in thirty remote lakes along an altitude gradient (420–2040ma.s.l.). Complete materials and data were collected in 24 lakes after one year. Detailed statistical analyses indicate that modern stomatocysts primarily respond to the length of the cold season. The TF model was then applied to the sedimentary stomatocysts from a 210Pb-dated short core of L. Escondida. Comparison to independent reanalysis data showed that reconstructed changes in Days T4°C provides detailed information on winter–spring temperature variability since AD 1920.The reconstruction shows that recent warming (onset in AD 1980) in the southern Chilean Andes was not exceptional in the context of the past century. This is in strong contrast to studies from the Northern Hemisphere. The finding is also in contrast to the cooling temperature trends which were detected using meteorological measurement data in low altitude sites along the Chilean coast. This finding confirms that coastal meteorological station data in this region do not reliably reflect recent temperature trends at high altitudes. Moreover, it implies a southward shift of the northern border of the Westerlies wind belt. This study clearly illustrates the importance of quantitative, high resolution studies from remote sites, in particular at high elevation mountain areas.

Abstract 10766: What is an Optimal Setting of Continuous-flow Left Ventricular Assist Device for Severe Mitral Regurgitation?

Introduction: Excessive volume unloading of the left ventricle (LV) affects the right ventricular (RV) function by causing shift of the ventricular septum during left ventricular assist device (LVAD) support in patients with mitral regurgitation (MR). Optimal settings of LVAD that control MR without RV dysfunction are required. We developed a novel cardiac-cycle synchronized rotational speed (RS) modulation system for a continuous-flow LVAD and assessed the system in a goat model of MR. Methods: We implanted EVAHEART (Sun Medical Technology Research Corp.) through left thoracotomy in six adult goats weighing 66.4 ± 10.7 kg. After implantation of the device, severe MR was induced with inflation of a temporary inferior vena cava filter that was placed in the mitral valve. The severity of MR was defined by left ventriculography and echocardiography. We evaluated total flow (TF: the sum of aortic flow and pump flow), RV fractional area change (RVFAC) calculated by echocardiography, left atrial pressure (LAP), LV end-diastolic pressure (LVEDP), LV end-diastolic volume (LVEDV), and LV stroke work (LVSW) with a bypass rate (pump flow divided by TF) of 100% under four conditions: circuit-clamp, continuous mode, co-pulse mode (increase RS in systole) and counter-pulse mode (increase RS in diastole). Results: TF tended to be higher in counter-pulse mode (3.27 ± 1.09, 3.51 ± 2.14, 3.45 ± 2.58, and 3.75 ± 2.39 L/min, in circuit-clamp, continuous mode, co-pulse mode, and counter-pulse mode, respectively; p > 0.05). RVFAC was significantly higher in counter-pulse mode than in co-pulse mode (0.68 ± 0.05 vs 0.51 ± 0.08 , p < 0.05). LAP was significantly lower in all the driving modes than in circuit-clamp. LVEDP, LVEDV and LVSW, shown as percentages of those in circuit-clamp (= 100%), were significantly lower in counter-pulse mode than in circuit-clamp (54.43 ± 32.05, 89.6 0 ± 4.23, and 60.30 ± 28.41 %, respectively; p < 0.05). Conclusions: Good control of MR in counter-pulse mode could be achieved with enough LV volume unloading during diastole not to leave blood that regurgitates during systole. Given higher TF and RVFAC in counter-pulse mode, the mode has less adverse effects on the RV function. In conclusion, the mode may offer a favorable control of MR with minimizing RV dysfunction.

Truncal and leg fat associations with metabolic risk factors among Chinese adults.

To examine the associations of regional body fat distribution with metabolic risk factors among Chinese. Truncal fat (TF) and leg fat (LF) were measured by dualenergy X-ray absorptiometry (DXA) among 947 adults, and abdominal visceral fat (VAT) and subcutaneous fat (SAT), upper leg SAT were measured by magnetic resonance image (MRI) among 103 adults during 2008-2013. Metabolic risk factors included fasting blood glucose, total triglyceride, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and metabolic syndrome (MetS). TF showed adverse effect while LF showed beneficial effect on metabolic risk factors, and all these effects were independent of body mass index (BMI) (mostly p<0.01). Individuals with higher TF and lower LF experienced the highest risk of MetS compared to other subgroups of combination of TF and LF (all p<0.05). Abdominal VAT was positively associated with risk of MetS (men: odds ratio (OR)=4.45, 95% confidence interval (CI): 1.18, 16.8; women: OR=6.54, 95% CI: 1.08, 39.6) and serum triglyceride (men: beta (β)=0.379, 95% CI: 0.090, 0.667; women: β=0.700, 95% CI: 0.327, 1.07). Upper leg SAT showed an opposite association with most metabolic factors compared to abdominal SAT and VAT, however, the association was not statistically significant. TF and LF showed opposite effects on metabolic risk factors among Chinese adults. Abdominal VAT, but not abdominal SAT, was positively associated with serum triglyceride and risk of MetS. Future studies are warranted to examine the potential mechanism of the opposite effects between TF and LF on metabolic risk factors among Chinese.

Thoracic fat volume is independently associated with coronary vasomotion.

Thoracic fat has been associated with an increased risk of coronary artery disease (CAD). As endothelium-dependent vasoreactivity is a surrogate of cardiovascular events and is impaired early in atherosclerosis, we aimed at assessing the possible relationship between thoracic fat volume (TFV) and endothelium-dependent coronary vasomotion. Fifty healthy volunteers without known CAD or major cardiovascular risk factors (CRFs) prospectively underwent a (82)Rb cardiac PET/CT to quantify myocardial blood flow (MBF) at rest, and MBF response to cold pressor testing (CPT-MBF) and adenosine (i.e., stress-MBF). TFV was measured by a 2D volumetric CT method and common laboratory blood tests (glucose and insulin levels, HOMA-IR, cholesterol, triglyceride, hsCRP) were performed. Relationships between CPT-MBF, TFV and other CRFs were assessed using non-parametric Spearman rank correlation testing and multivariate linear regression analysis. All of the 50 participants (58 ± 10y) had normal stress-MBF (2.7 ± 0.6 mL/min/g; 95 % CI: 2.6-2.9) and myocardial flow reserve (2.8 ± 0.8; 95 % CI: 2.6-3.0) excluding underlying CAD. Univariate analysis revealed a significant inverse relation between absolute CPT-MBF and sex (ρ = -0.47, p = 0.0006), triglyceride (ρ = -0.32, p = 0.024) and insulin levels (ρ = -0.43, p = 0.0024), HOMA-IR (ρ = -0.39, p = 0.007), BMI (ρ = -0.51, p = 0.0002) and TFV (ρ = -0.52, p = 0.0001). MBF response to adenosine was also correlated with TFV (ρ = -0.32, p = 0.026). On multivariate analysis, TFV emerged as the only significant predictor of MBF response to CPT (p = 0.014). TFV is significantly correlated with endothelium-dependent and -independent coronary vasomotion. High TF burden might negatively influence MBF response to CPT and to adenosine stress, even in persons without CAD, suggesting a link between thoracic fat and future cardiovascular events.

Suppressive effects of exogenous regucalcin on the proliferation of human pancreatic cancer MIA PaCa-2 cells in vitro.

Regucalcin plays a pivotal role as a suppressor protein in signal transduction in various types of cells and tissues. The regucalcin gene is localized on the X chromosome. and its expression has been shown to be suppressed in various types of tumor tissue in animal and human subjects, suggesting a potential role of regucalcin in carcinogenesis. This study was undertaken to determine the effects of exogenous regucalcin on the proliferation of cloned human pancreatic cancer MIA PaCa-2 cells in vitro. The proliferation of the MIA PaCa-2 cells was suppressed following culture with regucalcin (0.01-10 nM). Such an effect was also observed in pancreatic cancer Pt45P1 cells, that highly expressed tissue factor (high TF), or Pt45P1 cells, that highly expressed alternativly spliced variants of tissue factor (asTF). In the MIA PaCa-2 cells, the suppressive effects of regucalcin on cell proliferation were not enhanced either in the presence of tumor necrosis factor-α (TNF-α), or in the presence of Bay K 8644, PD98059, staurosporine, wortmannin or 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB). However, this was not the case for gemcitabine, which was shown to suppress cell proliferation. Exogenous regucalcin did not cause apoptotic cell death in the MIA PaCa-2 cells in vitro. These findings demonstrate that exogenous regucalcin exerts suppressive effects on the proliferation of human pancreatic MIA PaCa-2 cells and that these effects are mediated through the inhibition of various signaling pathways related to nuclear factor-κB (NF-κB), extracellular signal-regulated kinase (ERK), protein kinase C, calcium signaling, phosphatidylinositol 3-kinase (PI3K) or nuclear transcription activity in vitro. Our data suggest that exogenous regucalcin exerts suppressive effects on the proliferation of human pancreatic cancer cells.

Trypanosoma brucei gambiense Adaptation to Different Mammalian Sera Is Associated with VSG Expression Site Plasticity

Trypanosoma brucei gambiense infection is widely considered an anthroponosis, although it has also been found in wild and domestic animals. Thus, fauna could act as reservoir, constraining the elimination of the parasite in hypo-endemic foci. To better understand the possible maintenance of T. b. gambiense in local fauna and investigate the molecular mechanisms underlying adaptation, we generated adapted cells lines (ACLs) by in vitro culture of the parasites in different mammalian sera. Using specific antibodies against the Variant Surface Glycoproteins (VSGs) we found that serum ACLs exhibited different VSG variants when maintained in pig, goat or human sera. Although newly detected VSGs were independent of the sera used, the consistent appearance of different VSGs suggested remodelling of the co-transcribed genes at the telomeric Expression Site (VSG-ES). Thus, Expression Site Associated Genes (ESAGs) sequences were analysed to investigate possible polymorphism selection. ESAGs 6 and 7 genotypes, encoding the transferrin receptor (TfR), expressed in different ACLs were characterised. In addition, we quantified the ESAG6/7 mRNA levels and analysed transferrin (Tf) uptake. Interestingly, the best growth occurred in pig and human serum ACLs, which consistently exhibited a predominant ESAG7 genotype and higher Tf uptake than those obtained in calf and goat sera. We also detected an apparent selection of specific ESAG3 genotypes in the pig and human serum ACLs, suggesting that other ESAGs could be involved in the host adaptation processes. Altogether, these results suggest a model whereby VSG-ES remodelling allows the parasite to express a specific set of ESAGs to provide selective advantages in different hosts. Finally, pig serum ACLs display phenotypic adaptation parameters closely related to human serum ACLs but distinct to parasites grown in calf and goat sera. These results suggest a better suitability of swine to maintain T. b. gambiense infection supporting previous epidemiological results.

A novel tissue-engineered devitalized vascular prosthesis

increase, whereas chemical stimulation with Th alone led to significant TF expression (4.9±0.3-fold). The combination of mechanical-chemical stimuli induced significantly higher TF expression than mechanical stresses alone. LF+Th, PF+Th and TFF+Th for 2 hours induced synergistically significant increased TF expression (16.6±1.7, 14.8±2.4, 17.4±1.0 fold, respectively). Furthermore, only TFF demonstrated significantly higher sustained TF expression after 6 hours exposure, both with and without Th. Conclusions: While uniform laminar flow resulted in transient TF expression, TFF, which is analogous to disturbed flow, induced sustained amplification of TF expression even in the presence of chemical stimuli. These results provide important insight into the role of inflammatory reactions in EC, as it relates to localization of atherosclerosis at sites of disturbed flow.

Void structure in silica glass with different fictive temperatures observed with positron annihilation lifetime spectroscopy

We examine voids in silica glasses with different fictive temperatures using positron annihilation lifetime spectroscopy. The pick-off annihilation lifetime of ortho-positronium increases with the fictive temperature, Tf, indicating that the void size increases. High Tf leads to high density and low degree of network polymerization so that increasing void size means that the density fluctuation of the silica glass increases with high Tf. Assuming that such density fluctuation causes light scattering, the previously reported Tf dependence of the Rayleigh scattering coefficient can be well explained by the change in void size.

Cadmium tolerance and accumulation characteristics of mature flax, cv. Hermes: Contribution of the basal stem compared to the root

The potential of mature flax plants (cv. Hermes) to tolerate and accumulate cadmium (Cd) was studied to determine which part of the plant would be the key organ for phytoremediation purposes. After 4month-growth on sand substrate containing 0.1mM Cd in a greenhouse, the roots and stems were separated and the stems were divided into three parts. The effects of Cd were studied on growth parameters, histology and mineral nutrition. No visible toxic symptoms were observed. Tolerance-index values calculated from growth parameters and nutrients remained relatively high, allowing the development of the plant until maturity and formation of seeds. The roots and bottom stem accumulated the highest quantity of Cd (750 and 360mg/kg dry matter), values which largely exceeded the threshold defined for hyperaccumulators. On the other hand, basal stem had a high bioconcentration factor (BCF=32) and translocation factor TF′ (2.5) but a low TF (0.5), indicating that this basal part would play a major role in phytoremediation (phytostabilization rather than phytorextraction). Therefore, the high tolerance to Cd and accumulation capacity make possible to grow Hermes flax on Cd-polluted soils.

The role of footwear in attenuating impact loads in individuals with knee osteoarthritis

The role of footwear in attenuating impact loads in individuals with knee osteoarthritis

Effect of Firing Temperature on LSM-YSZ Composite Cathodes: A Combined Three-Dimensional Microstructure and Impedance Spectroscopy Study

(La0.8Sr0.2)MnO3-Yttria Stabilized Zirconia (LSM-YSZ) cathodes fired at various temperatures were studied using Focused Ion Beam – Scanning Electron Microscopy (FIB-SEM) three-dimensional (3D) tomography and Electrochemical Impedance Spectroscopy (EIS). The total cathode polarization resistance, measured at 800°C in air, showed a minimum versus firing temperature, Tf, at 1175°C. The EIS showed two dominant responses that were fit well using a two (R-CPE) element equivalent circuit. The higher frequency (104–105 Hz) response, attributed to YSZ grain boundary resistance within the LSM-YSZ composite, decreased with increasing Tf and was explained by grain size increases estimated from the 3D structural data. The main EIS response, attributed to the oxygen reduction process, decreased in characteristic frequency from 500 to 1 Hz as Tf increased, while its magnitude was minimized at 1175°C. An electrochemical model quantitatively predicted the resistance minimum based primarily on a maximum in the density of electrochemically-active three-phase boundaries (TPBs), measured using 3D tomography. The active TPB density maximum resulted from two factors: substantial particle coarsening and densification at high Tf that yielded a low TPB density, and low LSM-particle percolation at low Tf that yielded a low fraction of active TPBs.

Spin State Transitions in RECoO3 Investigated by μ+SR

The spin-state of RECoO3(RE = La, Pr, Nd, and PrxLa1−x)has been investigated by μ+SR experiments. In particular, the muonic Knight shift in a high TF of 10 kOe was studied at temperatures below 300 K. By combining these measurements with the dc-susceptibility data, the spin-state transition temperature(TSS)was found to increase monotonically as the average ionic radius of the RE ion is decreased. Our measurements demonstrate that TF-μ+SR is a unique technique to detect the spin-state transition in compounds regardless of coexistence of large magnetic moments through the change in microscopic magnetic environments at TSS.