Quantum Photon Sources in WSe₂ Monolayers Induced by Weakly Localized Strain Fields

Quantum emitters in semiconductor transition metal dichalcogenide (TMD) monolayers hold great promise for many quantum optics applications due to the intriguing properties afforded by the host materials. The creation of localized excitonic states in two-dimensional semiconductors is also fundamentally interesting. Local strain engineering of TMD monolayers has been attested to be a viable approach for creating quantum emitters. However, despite the ubiquitous existence of local topography variations in the structures used to create strain gradients in the TMD monolayers, an understanding of their influence on the strain fields and exciton trapping is notably lacking, especially on the nanoscale. In this study, we investigate WSe2 monolayers deposited on the edges of as-fabricated trenches, which are deemed to induce 1D delocalized strain profiles in the monolayers, and observe optical signatures of weakly confined excitonic states supporting biexciton emission. Our numerical simulations of the strain distributions suggest that the quantum emitters originate from quasi-1D like localized strain profiles induced by local topography variations at the trench edges. These findings have strong implications toward the controlled creation of quantum emitters in TMD monolayers and their efficient coupling to photonic structures

Combined bioremediation for lead in mine tailings by <i>Solanum nigrum L</i>. and indigenous fungi

<p>Lead-contaminated mine tailings were bioremediated using microbial/phyto remediation. The optimum lead accumulation and tolerance capacity of the plant–microbe partnership were investigated, and their mechanisms were evaluated further under varied levels of lead contamination through a flowerpot experiment in a greenhouse. Enzymes activities revealed that bioremediation has improved fertility and metabolism of tailing soil. The removal efficiency of lead was in the order of microbial/phytoremediation > phytoremediation. <i>Solanum nigrum</i> L. was not shown to be a hyperaccumulator for lead. <i>Mucor circinelloides</i> significantly enhanced the growth response and lead accumulation in plants more than <i>Mortierella</i> and <i>Trichoderma asperellum</i>. Moreover, <i>Mortierella</i> was discovered to have good metal tolerance capacity under high Pb concentrations (1200 and 1600 mg kg⁻¹). The results for lead bioavailability showed that phytostabilisation serves as a major repair pathway for <i>S. nigrum</i> L. Effective fractions were immobilised for decreased bioavailability by <i>T. asperellum</i> and <i>M. circinelloides</i>. On the contrary, an increased amount of lead was mobilised for increased bioavailability by <i>Mortierella.</i> This study provides new insights into the feasibility of using <i>S. nigrum</i> L. and the aforementioned indigenous fungus strains for large-scale bioremediation of mine tailings.</p

Microgravimetric Analysis Method for Activation-Energy Extraction from Trace-Amount Molecule Adsorption

Activation-energy (<i>E</i>_a) value for trace-amount adsorption of gas molecules on material is rapidly and inexpensively obtained, for the first time, from a microgravimetric analysis experiment. With the material loaded, a resonant microcantilever is used to record in real time the adsorption process at two temperatures. The kinetic parameter <i>E</i>_a is thereby extracted by solving the Arrhenius equation. As an example, two CO₂ capture nanomaterials are examined by the <i>E</i>_a extracting method for evaluation/optimization and, thereby, demonstrating the applicability of the microgravimetric analysis method. The achievement helps to solve the absence in rapid quantitative characterization of sorption kinetics and opens a new route to investigate molecule adsorption processes and materials

Assessment of Estrogenic Activity of Perfluoroalkyl Acids Based on Ligand-induced Conformation State of Human Estrogen Receptor

Perfluoroalkyl acids (PFAAs) have been reported to interfere with the endocrine system in vivo by mimicking endogenous hormone activities and causing adverse effects. Some exoestrogens bind to estrogen receptor (ER) and subsequently induce an ER-mediated response. The transcriptional activity of ER is regulated by its distinct conformational states that are the results of ligand binding. In this work, a biosensor based on surface plasmon resonance (SPR) technique was developed which can discriminate between agonist and antagonist of human ERα (hERα) by monitoring the conformation state of the protein induced by ligand binding. The biosensor utilized the specific interaction between hERα and conformation-selective peptides. Six PFAAs with different chain lengths and acid groups were tested by the biosensor, and perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were found to be ER agonists. Kinetic analyses of direct interaction between PFAAs and hERα by SPR revealed that PFOS and PFOA were both weak binders of ER with <i>K</i>_D values of 2.19 and 107 μM respectively, whereas the other four PFAAs did not bind with ER. To understand the differences in ER binding affinity and estrogenic activity among the six PFAAs, molecular docking based on the crystal structure of hERα ligand binding domain was performed. PFOS and PFOA were efficiently docked with hERα and formed hydrogen bonds with Arg394 in a manner similar to estradiol. Overall, the two 8-carbon PFAAs were assessed as weak agonists of hERα and are of potential concern

Microgravimetric Thermodynamic Modeling for Optimization of Chemical Sensing Nanomaterials

On the basis of microgravimetric sensing data, an analytical modeling method is proposed for comprehensive evaluation and optimization of gas sensing or adsorbing related functional materials. Resonant microcantilever is loaded with the material to be evaluated for a gravimetric sensing experiment. With sensing isotherm curves obtained at different temperatures, key thermodynamic and kinetic parameters of the material, such as enthalpy Δ<i><i>H</i>°</i>, Gibbs free energy, adsorption rate constant <i>K</i>_<i>a</i>, and coverage θ, etc., can be quantitatively extracted for optimal selection and design. On the basis of the gravimetric experiment, the modeling method is used on three sorts of trimethylamine sensing nanomaterials of mesoporous silica nanoparticles (MSNs). The COOH-functionalized material is clearly identified as the best sensing material among the three similar ones, thereby validating high accuracy of the proposed model. Broad applicability of the modeling method to other sensing materials and/or target gases is also experimentally confirmed, where sensing properties of a functionalized hyper-branched polymer to organophorous simulant of dimethyl methylphosphonate (DMMP) are still evaluated well. In addition to sensing materials, the gravimetric experiment-based modeling method can be expanded to other functional materials like moisture absorbents or detoxification agents. Water adsorbing experiment on KIT-5 mesoporous-silica is modeled, with the low −Δ<i><i>H</i>°</i> value (i.e., low adsorption heat) result, indicating that the KIT-5 is a good adsorbent to humidity. Alternatively, the modeled high −Δ<i><i>H</i>°</i> value (i.e., high reaction heat) shows promising usage of SBA-15 mesoporous-silica as detoxification material to hazardous organophorous chemicals. Therefore, the analytical modeling technology can be used for developing and evaluating new adsorbing materials for gas sensing, fixing, and detoxification applications

Amine-Functionalized SBA-15 with Uniform Morphology and Well-Defined Mesostructure for Highly Sensitive Chemosensors To Detect Formaldehyde Vapor

Amine-functionalized SBA-15 with uniform morphology and well-defined mesostructure was prepared using a postgrafting route. The morphology, mesostructure, and functionality of the materials were characterized by scanning electron microscopy, transmission electron microscopy, small-angle X-ray scattering, nitrogen adsorption–desorption, Fourier transform infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy techniques. The results show that hexagonal lamelliform SBA-15 with a uniform particle size and short vertical channels plays two significant roles in uniformly dispersing amine-functionalizing groups and effectively adjusting the loadings of the functional groups within the mesopore channels. To confirm the potential application of the hybrids in gas sensors, using amine-functionalized SBA-15 as a sensing material and a quartz crystal microbalance as a transducer, a parts per billion level formaldehyde sensor with high sensitivity (response time about 11 s, recovery time about 15 s) and good chemoselectivity was achieved. This material holds great potential in the area of rapid, sensitive, and highly convenient formaldehyde detection

Analysis of a common spoken language in Staňkov

The aim of this dialectological bachelor's thesis was to found out if and which characterictics features are appearing in the everyday speech of native speakers in Staňkov. In a brief way it described the specifics and general distribution of the Southwest bohemia dialect. The practical part focused on the observation of local language in the context of three generations

Nanomechanical Signatures of Extracellular Vesicles from Hematologic Cancer Patients Unraveled by Atomic Force Microscopy for Liquid Biopsy

Cells release extracellular vesicles (EVs) as the carriers for intercellular communications to regulate life activities. Particularly, it is increasingly apparent that mechanical forces play an essential role in biological systems. The nanomechanical properties of EVs and their dynamics in cancer development are still not fully understood. Herein, with the use of atomic force microscopy (AFM), the nanomechanical signatures of EVs from the liquid biopsies of hematologic cancer patients were unraveled. Single native EVs were probed by AFM under aqueous conditions. The elastic and viscous properties of EVs were measured and visualized to correlate EV mechanics with EV geometry. Experimental results remarkably reveal the significant differences in EV mechanics among multiple myeloma patients, lymphoma patients, and healthy volunteers. The study unveils the unique nanomechanical signatures of EVs in hematologic cancers, which will benefit the studies of liquid biopsies for cancer diagnosis and prognosis with translational significance

Locus- and Site-Specific DNA Methylation of 19 kDa Zein Genes in Maize

<div><p>An interesting question in maize development is why only a single zein gene is highly expressed in each of the 19-kDa zein gene clusters (A and B types), <i>z1A2</i>-1 and <i>z1B4</i>, in the immature endosperm. For instance, epigenetic marks could provide a structural difference. Therefore, we investigated the DNA methylation of the arrays of gene copies in both promoter and gene body regions of leaf (non-expressing tissue as a control), normal endosperm, and cultured endosperm. Although we could show that expressed genes have much lower methylation levels in promoter regions than silent ones in both leaf and normal endosperm, there was surprisingly also a difference in the pattern of the <i>z1A</i> and <i>z1B</i> gene clusters. The expression of <i>z1B</i> gene is suppressed by increased DNA methylation and activated with reduced DNA methylation, whereas <i>z1A</i> gene expression is not. DNA methylation in gene coding regions is higher in leaf than in endosperm, whereas no significant difference is observed in gene bodies between expressed and non-expressed gene copies. A median CHG methylation (25–30%) appears to be optimal for gene expression. Moreover, tissue-cultured endosperm can reset the DNA methylation pattern and tissue-specific gene expression. These results reveal that DNA methylation changes of the 19-kDa zein genes is subject to plant development and tissue culture treatment, but varies in different chromosomal locations, indicating that DNA methylation changes do not apply to gene expression in a uniform fashion. Because tissue culture is used to produce transgenic plants, these studies provide new insights into variation of gene expression of integrated sequences.</p></div

C methylation at CCG sites.

<p>Methylation levels of <i>z1A</i> (A, C) and <i>z1B</i> (B, D) gene coding regions in leaf (C, D) and endosperm (A, B) is shown. The methylation of outer and inner C is marked with mCCG (blue) and CmCG (red), respectively.</p