Nanoparticles formed on oxide surfaces are of key importance in many fields such as catalysis and renewable energy. Here, we control B-site exsolution via lattice strain to achieve a high degree of ...exsolution of nanoparticles in perovskite thin films: more than 1100 particles μm
with a particle size as small as ~5 nm can be achieved via strain control. Compressive-strained films show a larger number of exsolved particles as compared with tensile-strained films. Moreover, the strain-enhanced in situ growth of nanoparticles offers high thermal stability and coking resistance, a low reduction temperature (550 °C), rapid release of particles, and wide tunability. The mechanism of lattice strain-enhanced exsolution is illuminated by thermodynamic and kinetic aspects, emphasizing the unique role of the misfit-strain relaxation energy. This study provides critical insights not only into the design of new forms of nanostructures but also to applications ranging from catalysis, energy conversion/storage, nano-composites, nano-magnetism, to nano-optics.
Molecular fingerprint spectra obtained by surface-enhanced Raman spectroscopy (SERS) enable the trace analysis of chemical and biomedical materials, including toxic substances. However, molecules ...that undergo random diffusion have a lower probability of being positioned at a conventional hotspot, adversely affecting the sensitivity and the limit of detection. In the present work, we demonstrated in situ galvanic replacement (GR) in the presence of analytes to simultaneously form interior hotspots (i.e., voids and interstitials) and drive molecular dynamic diffusion to the desired areas. For GR, Ag nanopillars (AgNPs) partially substituted with Au (Au/AgNPs) were prepared. Their stoichiometric ratio induced the formation of interior hotspots with sufficient field enhancement, which provided femtomolar sensitivity (i.e., 100 fM) for methylene blue (MB) Raman dye in 10 s. The activation of the developed platform was verified by comparison with the post-addition of MB into the Au/AgNPs (i.e., dyes adsorbed onto the surfaces). The reproducibility was investigated using multiple specimens, which demonstrated stable operation, with a relative standard deviation of ∼10% at the analytic peaks of MB at 509, 1395, and 1623 cm−1. A linearly proportional relationship (R2 ≥ 0.94) was also found in quantitative studies. The Au/AgNPs were used for the trace analysis of toxic thiabendazole molecules at concentrations as low as 100 pM. The results show that the developed Au/AgNPs SERS platform demonstrates strong potential for use in on-site detection of toxic substances in a sensitive, reproducible, and rapid manner.
•Nanoscale cracks and hollows in Au/AgNPs prepared by GR functionalized as plasmonic hotspots.•Analytes being diffused into 3D interior hotspots indicated femtomolar sensitivity.•This facile strategy is desirable to trace toxic pesticides in practical fields.
Ferroelectric photovoltaics (FPVs) are being extensively investigated by virtue of switchable photovoltaic responses and anomalously high photovoltages of ∼104 V. However, FPVs suffer from extremely ...low photocurrents due to their wide band gaps (E g). Here, we present a promising FPV based on hexagonal YbFeO3 (h-YbFO) thin-film heterostructure by exploiting its narrow E g. More importantly, we demonstrate enhanced FPV effects by suitably exploiting the substrate-induced film strain in these h-YbFO-based photovoltaics. A compressive-strained h-YbFO/Pt/MgO heterojunction device shows ∼3 times enhanced photovoltaic efficiency than that of a tensile-strained h-YbFO/Pt/Al2O3 device. We have shown that the enhanced photovoltaic efficiency mainly stems from the enhanced photon absorption over a wide range of the photon energy, coupled with the enhanced polarization under a compressive strain. Density functional theory studies indicate that the compressive strain reduces E g substantially and enhances the strength of d–d transitions. This study will set a new standard for determining substrates toward thin-film photovoltaics and optoelectronic devices.
The protein size, electrical interaction, and conformational stability of etanercept (marketed as Enbrel®) were examined by thermodynamic and light scattering methods with changing pH and buffer ...concentration. As pH of etanercept increased from pH 6.6 to 8.6, electrical repulsion in the solution increased, inducing a decrease in protein size. However, the size changed less in high buffer concentration and irreversible aggregation issues were not observed; in contrast, aggregates of about 1000 nm were observed in low buffer concentration at the pH range. Three significant unfolding transitions (Tm) were observed by differential scanning calorimetry (DSC). Unlikely to Tm1, Tm2 and Tm3 were increased as the pH increased. Higher Tm at high buffer concentration was observed, indicating increased conformational stability. The apparent activation energy of unfolding was further investigated since continuous increase of Tm2 and Tm3 was not sufficient to determine optimal conditions. A higher energy barrier was calculated at Tm2 than at Tm3. In addition, the energy barriers were the highest at pH from 7.4 to 7.8 where higher Tm1 was also observed. Therefore, the conformational stability of protein solution significantly changed with pH dependent steric repulsion of neighboring protein molecules. An optimized pH range was obtained that satisfied the stability of all three domains. Electrostatic circumstances and structural interactions resulted in irreversible aggregation at low buffer concentrations and were suppressed by increasing the concentration. Therefore, increased buffer concentration is recommended during protein formulation development, even in the earlier stages of investigation, to avoid protein instability issues.
In Arabidopsis thaliana, CONSTANS (CO) plays an essential role in the regulation of photoperiodic flowering under long-day conditions. CO protein is stable only in the afternoon of long days, when it ...induces the expression of FLOWERING LOCUS T (FT), which promotes flowering. The blue-light photoreceptor FLAVIN-BINDING, KELCH REPEAT, F-BOX1 (FKF1) interacts with CO and stabilizes it by an unknown mechanism. Here, we provide genetic and biochemical evidence that FKF1 inhibits CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1)-dependent CO degradation. Light-activated FKF1 has no apparent effect on COP1 stability but can interact with and negatively regulate COP1. We show that FKF1 can inhibit COP1 homo-dimerization. Mutation of the coiled-coil domain in COP1, which prevents dimer formation, impairs COP1 function in coordinating flowering time. Based on these results, we propose a model whereby the light- and day length-dependent interaction between FKF1 and COP1 controls CO stability to regulate flowering time.
Display omitted
•Interior hotspots of Au/AgNCs were facilely prepared via a one-pot GR process.•Interstitials were activated for the E-field confinement and molecular pathways.•The Au/AgNC platform ...reliably showed sub-ppm sensitivity for four different PAEs.•Machine learning analyses based on PCA–LDA successfully classified PAE combinations.
The ecological and health risks of plasticizer accumulation have reached the global public agenda. For early screening of phthalate esters (PAEs), in the present study, we developed ultrasensitive and reliable bimetallic surface-enhanced Raman spectroscopy (SERS) platforms with Ag nanocavities galvanically replaced by Au (Au/AgNCs) at room temperature. A galvanic reaction (GR) coupled with the Kirkendall effect led to a large population of nanoscale hollow regions within 60 s. The interstitials at the bimetallic shells were activated as both interior hotspots for field confinement and diffusion pathways for small target molecules. The GR based on the intrinsic material properties resulted in an Au/AgNC platform with reliable sensing operation, including a relative standard deviation of <10 % at the individual analytic Raman peaks. The qualified and densified interior hotspots of the Au/AgNC platform led to sub-ppm sensitivity (i.e., the average limit of detection of ∼2.1 × 10−2 ppm) for four different PAEs. As a demonstration of the Au/AgNC platform's performance in actual sample environments, the detection and identification of various PAE combinations were also investigated. Subtle differences in the PAEs' spectral characteristics (i.e., peak positions and intensity ratios) were successfully classified using a machine learning algorithm based on a principal component analysis–linear discriminant analysis model. Furthermore, the amount of PAE released from the real sample and evaluated by SERS was consistent with that evaluated by gas chromatography–mass spectrometry. These results indicate that the SERS platforms with Au/AgNC substrates and portable Raman instruments are suitable for on-site safety monitoring of toxic substances in food and the environment.
(1) Background: The intravoxel incoherent motion (IVIM) model can provide information about both molecular diffusion and blood flow for the evaluation of skeletal muscle inflammation. MRI-based fat ...quantification is advantageous for assessing fat infiltration in skeletal muscle. (2) Purpose: We aimed to quantitatively measure various parameters associated with IVIM diffusion-weighted imaging (DWI) and fat quantification in the muscles of patients with polymyositis and dermatomyositis using magnetic resonance imaging and to investigate the relationship between these parameters and electromyography (EMG) findings. (3) Material and methods: Data were retrospectively evaluated for 12 patients with polymyositis and dermatomyositis who underwent thigh MRI, including IVIM-DWI and fat quantification. The IVIM-derived parameters included the pure diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (
). Fat fraction values were assessed using the six-point Dixon technique. Needle EMG was performed within 9 days of the MRI. (4) Results: The
values (19.02 ± 4.87%) in muscles with pathological spontaneous activity on EMG were significantly higher than those (14.60 ± 5.31) in muscles without pathological spontaneous activity (
< 0.027). There were no significant differences in D, D*, ADC, or fat fraction between muscles with and without pathologic spontaneous activity. Significant negative correlations were observed between fat fraction and amplitude (
= -0.402,
< 0.015) and between fat fraction and duration (
= -0.360,
< 0.031). (5) Conclusion: The current study demonstrates that IVIM-DWI and fat quantification using 3.0 T MRI may aid in predicting EMG findings in patients with polymyositis and dermatomyositis and promote the pathophysiological study of idiopathic inflammatory myopathies.
Mammalian methionyl-tRNA synthetase (MRS) plays an essential role in initiating translation by transferring Met to initiator tRNA (tRNAiMet). MRS also provides a cytosolic anchoring site for ...aminoacyl-tRNA synthetase-interacting multifunctional protein-3 (AIMP3)/p18, a potent tumor suppressor that is translocated to the nucleus for DNA repair upon DNA damage. However, the mechanism by which this enzyme mediates these two seemingly unrelated functions is unknown. Here we demonstrate that AIMP3 is released from MRS by UV irradiation-induced stress. Dissociation was induced by phosphorylation of MRS at Ser662 by general control nonrepressed-2 (GCN2) following UV irradiation. Substitution of Ser662 to Asp (S662D) induced a conformational change in MRS and significantly reduced its interaction with AIMP3. This mutant possessed significantly reduced MRS catalytic activity because of loss of tRNAMet binding, resulting in down-regulation of global translation. According to the Met incorporation assay using stable HeLa cells expressing MRS S662A or eukaryotic initiation factor-2 subunit-α (eIF2α) S51A, inactivation of GCN2-induced phosphorylation at eIF2α or MRS augmented the role of the other, suggesting a cross-talk between MRS and eIF2α for efficient translational inhibition. This work reveals a unique mode of regulation of global translation as mediated by aminoacyl-tRNA synthetase, specifically MRS, which we herein identified as a previously unidentified GCN2 substrate. In addition, our research suggests a dual role for MRS: (i) as a coregulator with eIF2α for GCN2-mediated translational inhibition; and (ii) as a coupler of translational inhibition and DNA repair following DNA damage by releasing bound tumor suppressor AIMP3 for its nuclear translocation.
Reversible modifications of target proteins by small ubiquitin-like modifier (SUMO) proteins are involved in many cellular processes in yeast and animals. Yet little is known about the function of ...sumoylation in plants. Here, we show that the SIZ1 gene, which encodes an Arabidopsis SUMO E3 ligase, regulates innate immunity. Mutant siz1 plants exhibit constitutive systemic-acquired resistance (SAR) characterized by elevated accumulation of salicylic acid (SA), increased expression of pathogenesis-related (PR) genes, and increased resistance to the bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000. Transfer of the NahG gene to siz1 plants results in reversal of these phenotypes back to wild-type. Analyses of the double mutants, npr1 siz1, pad4 siz1 and ndr1 siz1 revealed that SIZ1 controls SA signalling. SIZ1 interacts epistatically with PAD4 to regulate PR expression and disease resistance. Consistent with these observations, siz1 plants exhibited enhanced resistance to Pst DC3000 expressing avrRps4, a bacterial avirulence determinant that responds to the EDS1/PAD4-dependent TIR-NBS-type R gene. In contrast, siz1 plants were not resistant to Pst DC3000 expressing avrRpm1, a bacterial avirulence determinant that responds to the NDR1-dependent CC-NBS-type R gene. Jasmonic acid (JA)-induced PDF1.2 expression and susceptibility to Botrytis cinerea were unaltered in siz1 plants. Taken together, these results demonstrate that SIZ1 is required for SA and PAD4-mediated R gene signalling, which in turn confers innate immunity in Arabidopsis.
PDF
