CsPbBr3 is a promising type of light‐emitting halide perovskite with inorganic composition and desirable thermal stability. The luminescence efficiency of pristine CsPbBr3 thin films, however, ...appears to be limited. In this work, light emitting diodes based on CsPbBr3|Cs4PbBr6 composites are demonstrated. Both quantum efficiency and emission brightness are improved significantly compared with similar devices constructed using pure CsPbBr3. The high brightness can be attributed to the enhanced radiative recombination from CsPbBr3 crystallites confined in the Cs4PbBr6 host matrix. The unfavorable charge transport property of Cs4PbBr6 can be circumvented by optimizing the ratio between the host and the guest components and the total thickness of the composite thin films. The inorganic composition of the emitting layer also leads to improved device stability under the condition of continuous operation.
Light emitting diodes based on CsPbBr3|Cs4PbBr6 composites are demonstrated with improved quantum efficiency, emission brightness, and device stability. The high brightness can be attributed to the enhanced radiative recombination from CsPbBr3 crystallites confined in the Cs4PbBr6 host matrix. The unfavorable charge transport property of Cs4PbBr6 can be circumvented by optimizing the ratio and thickness of the CsPbBr3|Cs4PbBr6 composite perovskite layer.
Abstract
Chirality has been a property of central importance in physics, chemistry and biology for more than a century. Recently, electrons were found to become spin polarized after transmitting ...through chiral molecules, crystals, and their hybrids. This phenomenon, called chirality-induced spin selectivity (CISS), presents broad application potentials and far-reaching fundamental implications involving intricate interplays among structural chirality, topological states, and electronic spin and orbitals. However, the microscopic picture of how chiral geometry influences electronic spin remains elusive, given the negligible spin-orbit coupling (SOC) in organic molecules. In this work, we address this issue via a direct comparison of magnetoconductance (MC) measurements on magnetic semiconductor-based chiral molecular spin valves with normal metal electrodes of contrasting SOC strengths. The experiment reveals that a heavy-metal electrode provides SOC to convert the orbital polarization induced by the chiral molecular structure to
spin
polarization. Our results illustrate the essential role of SOC in the metal electrode for the CISS spin valve effect. A tunneling model with a magnetochiral modulation of the potential barrier is shown to quantitatively account for the unusual transport behavior.
Schematic diagram of the experiments. Embryonic stem cells (ESCs) were seeded in suspension to generate undifferentiated aggregates (AGG), spontaneous embryoid bodies (EBs), or to derive neural ...progenitor cell (NPC) aggregates. The three types of aggregates were then decellularized (DE) to generate DE-A, DE-E, and DE-N scaffolds. The derived extracellular matrices (ECMs) were treated with genipin (G) or glutaraldehyde (GL) to obtain the crosslinked scaffolds. The non-crosslinked ECMs were used as controls (C). ESC-derived NPCs were seeded onto various ECM scaffolds and characterized. Display omitted
At various developmental stages, pluripotent stem cells (PSCs) and their progeny secrete a large amount of extracellular matrices (ECMs) which could interact with regulatory growth factors to modulate stem cell lineage commitment. ECMs derived from PSC can be used as unique scaffolds that provide broad signaling capacities to mediate cellular differentiation. However, the rapid degradation of ECMs can impact their applications as the scaffolds for in vitro cell expansion and in vivo transplantation. To address this issue, this study investigated the effects of crosslinking on the ECMs derived from embryonic stem cells (ESCs) and the regulatory capacity of the crosslinked ECMs on the proliferation and differentiation of reseeded ESC-derived neural progenitor cells (NPCs). To create different biological cues, undifferentiated aggregates, spontaneous embryoid bodies, and ESC-derived NPC aggregates were decellularized. The derived ECMs were crosslinked using genipin or glutaraldehyde to enhance the scaffold stability. ESC-derived NPC aggregates were reseeded on different ECM scaffolds and differential cellular compositions of neural progenitors, neurons, and glial cells were observed. The results indicate that ESC-derived ECM scaffolds affect neural differentiation through intrinsic biological cues and biophysical properties. These scaffolds have potential for in vitro cell culture and in vivo tissue regeneration study.
Dynamic interactions of acellular extracellular matrices and stem cells are critical for lineage-specific commitment and tissue regeneration. Understanding the synergistic effects of biochemical, biological, and biophysical properties of acellular matrices would facilitate scaffold design and the functional regulation of stem cells.
The present study assessed the influence of crosslinked embryonic stem cell-derived extracellular matrix on neural differentiation and revealed the synergistic interactions of various matrix properties.
While embryonic stem cell-derived matrices have been assessed as tissue engineering scaffolds, the impact of crosslinking on the embryonic stem cell-derived matrices to modulate neural differentiation has not been studied.
The results from this study provide novel knowledge on the interface of embryonic stem cell-derived extracellular matrix and neural aggregates. The findings reported in this manuscript are significant for stem cell differentiation toward the applications in stem cell-based drug screening, disease modeling, and cell therapies.
Agglomerates of polar molecules in nonpolar solvents are selectively heated by microwave radiation. The magnitude of the selective heating was directly measured by using the temperature dependence of ...the intensities of the Stokes and anti-Stokes bands in the Raman spectra of p-nitroanisole (pNA) and mesitylene. Under dynamic heating conditions, a large apparent temperature difference (ΔT) of over 100 °C was observed between the polar pNA solute and the nonpolar mesitylene solvent. This represents the first direct measurement of the selective microwave heating process. The magnitude of the selective microwave heating was affected by the properties of the agglomerated pNA. As the concentration of the pNA increases, the magnitude of the selective heating of the pNA was observed to decrease. This is explained by the tendency of the pNA dipoles to orient in an antiparallel fashion in the aggregates as measured by the Kirkwood g value, which decreased with increasing concentration. This effect reduces the net dipole moment of the agglomerates, which decreases the microwave absorption. After the radiation was terminated, the effective temperature of the dipolar molecules returned slowly to that of the medium. The slow heat transfer was modeled successfully by treating the solutions as a biphasic solvent/solute system. Based on modeling and the fact that the agglomerate can be heated above the boiling temperature of the solvent, an insulating layer of solvent vapor is suggested to form around the heated agglomerate, slowing convective heat transfer out of the agglomerate. This is an effect unique to microwave heating.
In aprotic solvents, Lewis basic F– anion reduces Lewis acidic Ag(I) cation to Ag(0), forming metallic silver mirrors on the inner surfaces of reaction vessels and luminescent Ag-nanoparticles ...(AgNPs) in supernatant solutions, which emit blue light upon UV irradiation. The F–-induced formation of silver mirrors and AgNPs was confirmed through X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), fluorescence spectroscopy, and mass spectrometry, whereas the Ag(I)-induced oxidation of F– to Ḟ radical, followed by its conversion to HF2 – via H-abstraction and H-bonding, was evident from 19F NMR spectroscopy. This redox reaction is deactivated in water, as the reducing power of hydrated F– diminishes drastically. Less Lewis basic Cl–, Br–, and I– ions do not reduce Ag(I) to Ag(0), instead they can only form Ag(I) halide precipitates irrespective of protic or aprotic solvents. The Ag-coated surfaces, luminescent AgNPs, and Ḟ radicals produced by this unprecedented redox reaction could be exploited as electrodes, light-emitting materials, and radical initiators, respectively.
Surface adsorption of organic molecules provides a new method for the robust manipulation of ferromagnetism in (Ga,Mn)As. Electron acceptor and donor molecules yield significant enhancement and ...suppression, respectively, of ferromagnetism with modulation of the Curie temperature spanning 36 K. Dip‐pen nanolithography is employed to directly pattern monolayers on (Ga,Mn)As, which is presented as a novel pathway toward producing magnetic nanostructures.
Our examination of net phytoplankton collected from coastal localities in Odisha on the east coast of India, including Chilka Lake, Chandrabhaga Beach and Puri, in December 2015, revealed the ...overwhelming dominance of
Thalassiosira mala
, a gelatinous colony-forming, potentially harmful, marine planktonic diatom. The large numbers of cells allowed us to observe details of the cingulum not previously reported. The epicingulum is composed of four open bands including an areolated valvocopula, an areolated copula and two non-areolated pleurae. The immature hypocingulum includes at least two bands. Openings of alternate bands are arranged in a dextral pattern. Based on previous reports from the west coast and our current findings,
Thalassiosira mala
appears to be a common, widely distributed primary producer in Indian coastal waters. The presence of morphologically similar species, especially those <20 μm in diameter, underscores the importance of reliable species-level taxonomy using appropriate techniques for meaningful ecological and biogeographic considerations and for monitoring potentially harmful algae in India’s economically important coastal waters. Published reports suggest that
Thalassiosira mala
is widely distributed in temperate and tropical waters, present in 26 of 232 ecoregions and 18 of 62 provinces recognized in a recent classification of coastal marine ecoregions.
A carbon copy that's in a glass of its own: Nanoparticle structures are formed from the gelation of a silica sol–gel solution and the precipitation of a KIXNiIIYFeIII(CN)6 Prussian‐blue analogue in ...the sol–gel solution. Calcination of the resulting nanoparticle glass destroys the complex, leaves imprints in the silica, and deposits graphite crystals oriented along the long dimension of the void.
The complex equilibria associated with the hydrogenation of CO2 to form valuable products are of considerable interest for the remediation of CO2. Due to the potential usefulness of these reactions, ...alternative methods of driving them more favorably using alternative energy sources, such as microwave radiation, are also of interest. We report here a study of the methanation reaction that yields CH4, which was studied under microwave and conventional convective heating conditions. An essential part of the science that arises from such studies is characterizing the microwave-specific effects on the reaction. From the determined equilibrium constants, we found that microwave radiation strongly inhibited the formation of CH4. The effective thermodynamic parameters obtained from a van’t Hoff plot reflect this inhibition. The enthalpy under microwave conditions is −38.63 kJ/mol, compared to −180.02 kJ/mol under conventional heating methods. Similarly, the free energy across the temperature range is less negative, suggesting a decrease in spontaneity under microwave conditions. We also observed a significant difference in the entropy, with entropy of −52 J/mol under microwave conditions and −206 J/mol under conventional conditions. This is consistent with prior observations that microwaves do not accelerate exothermic reactions. As discussed, this difference may arise from the microwave-driven dissociation of the reactant before CH4 bonds are made. Analysis of this system is of interest in understanding how the microwave inhibits the formation of the products of exothermic reactions. These results are of significance for understanding the broad area of microwave driven heterogeneous catalysis.
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