In‐situ flash experiments on rutile TiO2 were performed at the synchrotron at the Brookhaven National Laboratory. Pair distribution function analysis of total X‐ray scattering measurements yielded ...mean‐square atomic displacements of oxygen and titanium atoms during the progression of the 3 stages of flash. The displacements are measured to be far greater for oxygen atoms than for titanium atoms. These large displacements may signal an “elastic softening” of the lattice, which, recently, has been predicted as a precursor to the onset of flash.
In this paper, we discuss the progression of flash sintering in 10mol% gadolinium-doped ceria specimens. Flash transition is correlated with the generation of n-type electronic conductivity in air ...under direct-current bias. Its origin is attributed to partial reduction of the material which propagates from the cathodic-to-anodic region. The phenomenon was observed, in-situ, by monitoring the development of electrochemical blackening during the incubation period of the flash-experiment. Anomalous features, including shift in the valence band edge, shrinkage of the band-gap and change in the oxidation state of Ce in flashed samples was confirmed by X-ray photoelectron spectroscopy and diffuse reflectance measurements.
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In this study, a BaTiO
3
/Ag/WO
3
nanocomposite was chemically synthesized for its gas sensing properties towards LPG. The formation of the novel BaTiO
3
/Ag/WO
3
nanocomposite was confirmed by XRD, ...TEM and FTIR analyses using the peak positions, observed planes, and existing vibrational bands, respectively with, Ag NPs of ~ 24 nm. The direct band gap 3.1 eV and absorption edge (411 nm) of the BaTiO
3
/Ag/WO
3
nanocomposite were determined using UV–Vis spectroscopy. The vibrational bands at 471, 504, 804, and 1636 cm
−1
are attributed to the interaction of silver with O–W–O and W–O–W in WO
3
, Ti–O in BTO, and C–O, respectively in the BTO/Ag/WO
3
nanocomposite. The higher dielectric constant and activation energy were estimated to be 2342 and 9.7 meV respectively. The sensitivity towards LPG at high temperature was ~ 99% with ~ 88 µA
I
a.c.
, while a.c. conductivity was very small at high temperatures. Long-time stability (30 days) with lower response time (10-4 s) and recovery time (17–21 s) were achieved. The limit of detection for LPG was found 205 ppm.
Graphical abstract
We report first‐time results for in‐operando flash sintering synchrotron experiments carried out in current rate mode where the specimen, held at a constant temperature, is fed current that is ...increased at a constant rate. These experiments are unique because the time dependence of the sintering behavior can be stretched out over a longer period (by changing the current rate) than in voltage‐to‐current experiments in which sintering occurs in a burst at the onset of the flash. Two results are presented: (i) A comparison of temperatures measured with the platinum standard to those predicted by the black body radiation model leading to estimates of the emissivity as a function of porosity whereby emissivity increases from 0.65 to 0.9 as the sample sinters from its green state to full density, and (ii) measurements of the excess lattice expansion as a function of density as the sample sinters continuously while the current is increased. The present work highlights the promise of current rate experiments to obtain results while the sample sinters gradually from its green density to full density (somewhat akin to conventional sintering) for gaining further insights into the mechanisms of flash sintering.
In this work, BaFe
2
O
4
(BFO) nanoparticles were synthesized using chemical coprecipitation technique and the BFO/SiC/TiO
2
nanocomposites synthesized further by undergoing solid state synthesis ...route with varying (10, 20, 30 and 40) wt% BFO. The structural, morphological, optical, and dielectric properties of these nanocomposites were determined using XRD, SEM, EDX, UV–vis, FTIR, and LCR meter. The phases in BFO/SiC/TiO
2
nanocomposites such as orthorhombic BFO, cubic SiC, hexagonal SiC, and tetragonal TiO
2
were validated with COD file no. 430-9915, JCPDS file no. 29-1129, JCPDS file no. 89-3843, and JCPDS file no. 21-1272 respectively. The absorption edges and energy band gaps were estimated in the range from 252 to 256 nm and 3.1–3.8 eV respectively indicating the absorbance in UV-C region. Further, the banding and stretching vibration bonds were found at around 438 cm
−1
, 414 cm
−1
, 858 cm
−1
, and 1450 cm
−1
for Ti–O, Fe–O, Si–C, and Ba–O respectively. The highest dielectric constant ~ 8941 was found for 30 wt% BFO at 28 ℃. Furthermore, the response of 30 wt% BFO indicated appreciable sensitivity towards NH
3
(g) at three intermediate temperatures 160 ℃, 210 ℃, and 250 ℃ due to individual and combined effect of BFO, TiO
2
, and SiC nanomaterials. Moreover, the average response time ~ 1.5 s and recovery time ~ 57 s were recognised by setting 39% RH at 28 ℃.
The polymer‐based synthesis of ceramics such as SiCO (and SiCN) leads to the incorporation of significant amounts of carbon into their molecular structure. A key feature of the nanostructure of these ...polymer‐derived ceramics is the revelation of persistent, 1–5 nm size domains by small‐angle X‐ray scattering. Here we present a model for these nanodomains, which is consistent with the nuclear magnetic resonance (NMR) data and with the phenomenological properties of SiCO (high resistance to creep and viscoelastic behavior). The model consists of clusters of silica tetrahedra encased within an interdomain wall constituted from mixed bonds of SiCO, and from a network of sp2 carbon. The model predicts the domain size as a function of the carbon content. These predictions are in reasonable agreement with the measurements of the nanodomains in SiCO synthesized with varying carbon contents (the domain size decreases with higher carbon). Simple maps are developed for easy reading of the domain size and the width of the interdomain boundary in the composition diagrams.
Opinion statement
The classification of mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) is evolving, and no clear management guidelines are currently available. However, recent studies ...provide insight into factors affecting outcomes and could help develop treatment decisions for patients with these rare malignancies. The majority of MiNENs have a poorly differentiated neuroendocrine carcinoma (NEC) component which is associated with an aggressive clinical course and poor outcomes. Due to the paucity of clinical trials, strategies adopted in gastrointestinal cancers and NECs are used to manage MiNENs. It is also to be noted that the thoracic neuroendocrine neoplasm WHO 2021 classification does not recognize MiNEN terminology but suggests an equivalent terminology called “combined neuroendocrine non neuroendocrine neoplasm.” Surgical management is appropriate in early-stage disease with a low threshold for addition of adjuvant chemotherapy. Multimodality treatment with chemotherapy offers a survival benefit in advanced disease or when surgical resection is not possible without significant morbidity. Chemotherapy should be directed at the more aggressive component which is often the NEC component. In addition, molecular testing should be employed to evaluate patients for enrollment in clinical trials and other targeted treatments. Being a rare disease with retrospective studies and case series providing the majority of data on treatment selection, it is essential to include more granular details of pathology (e.g., Ki-67, mitotic index, percentage of each component, staging information) and treatment modalities (e.g., type and duration, rationale, radiologic response, survival outcomes) in future studies to make systematic reviews possible and help derive meaningful conclusions.
Mixed powders of Bi2O3 and Fe2O3 are shown to yield single-phase, dense nanostructured polycrystals of BiFeO3 in reaction flash sintering experiments, carried out by applying a field of 50 V cm−1 and ...with the current limit set to 35 mA mm−2. The furnace was heated at a constant rate with the reaction sintering taking place abruptly upon reaching 625 °C. Remarkably, an intermediate bismuth-rich phase of the oxide that forms just before reaching the flash temperature transforms, and at the same time sinters, into single-phase BiFeO3 within a few seconds after the onset of the flash. The BiFeO3 so produced is electrically insulating, a property that is critical to its applications. This one-step synthesis of single-phase polycrystals of complex oxides from their basic constituents, by reaction flash sintering, is a significant development in the processing of complex oxides, which are normally difficult to sinter by conventional methods.
► The mGluR5 receptor internalizes constitutively in HEK293 cells. ► mGluR5 enters the recycling endosome subsequent to constitutive internalization. ► Constitutively endocytosed mGluR5 does not go ...to the lysosome for degradation. ► The mGluR5 recycles back to the cell surface in HEK293 cells.
Ligand-dependent and ligand-independent endocytic trafficking of G-protein coupled receptors (GPCRs) is critical for accurate receptor-mediated signaling and its regulation. Metabotropic glutamate receptor 5 (mGluR5) is a GPCR that plays a crucial role in circuit formation in the brain and also in various forms of synaptic plasticity including learning and memory. Outside the central nervous system this receptor also plays very important role in various other non-neuronal cells like heart cells, skin cells, hepatocytes, etc. Although the ligand-mediated endocytosis of mGluR5 has been studied in some detail, ligand-independent/constitutive endocytosis of the receptor has not been properly studied. Here, we have investigated the constitutive endocytosis of mGluR5 and also the sub-cellular fate of the receptor subsequent to internalization. We show here that mGluR5 undergoes constitutive internalization in HEK293 cells. Following endocytosis, the receptor enters the recycling compartment and no localization of the receptor was observed in the lysosome. In addition, we also report here that most of the receptors recycle to the cell surface subsequent to constitutive internalization. Thus, our data demonstrate that mGluR5 receptors internalize without the application of ligand and the internalized receptors recycle back to the cell surface following constitutive endocytosis.
Lithium-ion batteries constructed with an oxide electrolyte are a subset of solid-state batteries. The ceramics are hard and brittle which poses contact issues related to the metal-electrolyte ...interface. Recent experiments have shown that the electrochemical current of lithium across the interface can have significant spatial variability. For example, high local flux can nucleate voids at the interface, causing the cell to fail at low values of critical current density. Application of stack pressure compensates for the spatially non-uniform electrochemical current with mechanical currents of lithium, such that the sum of the mechanical and electrical currents, across the entire interface becomes uniform. Two scenarios for compensating mechanical currents are presented. In one case, called Type I, compression creep normal to the interface plane produces greater flow of lithium into high conductivity regions and less so to the low conductivity regimes, thereby equalizing the sum of electrical (with a negative sign) and mechanical (with a positive sign) currents. In Type II, stack pressure causes lithium to be transported by diffusion, parallel to the interface from regions of low, to regions of high electrochemical current to ensure that the lithium interface moves like a rigid body. The time dependent deformation in the lithium layer is matched with the current density to derive equations for the critical current density as a function of the stack pressure. Experimental data, though limited, when compared to these predictions shows better agreement with the Type II mechanism.
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