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IMPOSING BIAXIAL STRAIN ON 2D LAYERED MATERIALS BY LIQUID-INDUCED SWELLING OF SUPPORTING POLYMER
Sampathkumar, Krishna; Pekárek, J.; Frank, Otakar
2021 - English
2D layered materials promise to revolutionize the field of electronics, photonics, optoelectronics, energy storage, and sensing, etc. 2D materials have exceptional mechanical properties, with critical elongation >10%. Employing the strain to manipulate the electronic structure of these 2D materials could lead to further improvement of their implementation in many aspects. The ease of manipulation of their electronic structure can be one of the critical factors for their utilization in photonic devices. Apart from the strain, which decreases (increases) the bandgap energy at the rate of similar to 100 meV under 1% of biaxial tension (compression), also the layer number causes bandgap energy change of, e.g., 0.5 eV between bulk (1.3 eV) and monolayer MoS2 (1.8 eV). In our work, we focus on using the swelling behavior of PMMA/SU8 polymer in methanol to impose the strain on 2D layered materials. In the first trials, we have shown that it is possible to reach a strain gradient from 0 to similar to 0.5% of biaxial strain via simple swelling of polymer substrates, both for graphene [1] and transition metal di-chalcogenides (TMDC) like MoS2. Raman spectroscopy was used to probe the lattice strain in the materials through measuring changes of vibrational frequencies, and photoluminescence was used to probe the strain-induced bandgap character and energy in TMDC at room temperature. The surface corrugation of the 2D material after the soaking was recorded with the help of atomic force microscope (AFM).
Keywords:
raman-spectroscopy; graphene; monolayer; bubbles; 2D material; graphene; tmdc; strain engineering; biaxial strain
Available in digital repository of the ASCR
IMPOSING BIAXIAL STRAIN ON 2D LAYERED MATERIALS BY LIQUID-INDUCED SWELLING OF SUPPORTING POLYMER
2D layered materials promise to revolutionize the field of electronics, photonics, optoelectronics, energy storage, and sensing, etc. 2D materials have exceptional mechanical properties, with critical ...
Novel photochemical vapor generation of rhenium for its ultratrace determination
Vyhnanovský, Jaromír; Hašlová, K.; Musil, Stanislav
2021 - English
The presentation focused on novel photochemical vapor generation of rhenium. Details on optimization of generation conditions and other important parameters regarding this sensitive methodology, as well as its possible applications were pointed out and discussed.
Keywords:
photochemical vapor generation; inductively coupled plasma mass spectrometry; rhenium
Available in digital repository of the ASCR
Novel photochemical vapor generation of rhenium for its ultratrace determination
The presentation focused on novel photochemical vapor generation of rhenium. Details on optimization of generation conditions and other important parameters regarding this sensitive methodology, as ...
Separation of Racemic D,L-Tryptophan Using Chiral Membranes.
Čížek, Jan
2021 - English
The presented results open a discussion on selectivity towards L-Tryptophan and other enantiomerically pure biochemical molecules and suggest direction for further research.
Keywords:
chiral drugs; membrane processes; pure biochemical molecules
Available in a digital repository NRGL
Separation of Racemic D,L-Tryptophan Using Chiral Membranes.
The presented results open a discussion on selectivity towards L-Tryptophan and other enantiomerically pure biochemical molecules and suggest direction for further research.
Amine-functionalized Porous Polymers for Selective CO2 Adsorption.
Setničková, Kateřina; Jeřábek, Karel; Strašák, Tomáš; Soukup, Karel
2021 - English
Porous materials have always attracted high scientific interest because of their outstanding performance and potential applications in various fields, including adsorption and gas separation. Hyper-crosslinked polymers (HCLPs) have several advantages over other porous materials, they show extremely high surface areas and porosity, low density, outstanding adsorption properties, high chemical, and thermal stability.\nHerein, we reported a synthesis, characterization, and the CO2 (and other gases) adsorption performance of series of novel styrene-divinylbenzene based HCPs. The material was prepared in two steps. The first step involved the radical copolymerization of divinylbenzene (DVB) and 4-vinylbenzyl chloride (VBC), under solvothermal condition to generate porous polymers with high surface area above 700 m2 g−1. In the second step, various polyamine species were applied to react with the alkyl chloride groups and functionalize the pore surface\nto improve the CO2/N2, CO2/CH4 and CO2/H2 selectivity.
Keywords:
hyper-crosslinked polymers; synthesis; adsorption
Available in a digital repository NRGL
Amine-functionalized Porous Polymers for Selective CO2 Adsorption.
Porous materials have always attracted high scientific interest because of their outstanding performance and potential applications in various fields, including adsorption and gas separation. ...
Short-term application of elevated temperature and drought influences the isotopic composition of winter wheat grains
Pernicová, Natálie; Urban, Otmar; Čáslavský, Josef; Klem, Karel; Trnka, Miroslav
2021 - English
The study aimed to determine the differences in carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in grains of three winter wheat varieties grown under optimal and stress conditions. We found that the wheat variety has a significant effect on both δ13C and δ15N isotope ratios. Short-term (nine days) exposure to drought and high temperature during the heading or stem extension development phase significantly enhanced δ13C values, but only high temperature affected δ15N values. Enhanced δ15N values support the assumption that global warming causes a higher representation of the 15N isotope in plants. Moreover, significant interactive effects of temperature and water availability on the values of both isotopes were found implying that C and N metabolisms have been altered under the investigated stress conditions. We conclude that δ13C and δ15N isotope ratios of cereal grains are sensitive indicators of stress conditions, even short-term ones
Keywords:
wheat; grain; 13C; 15N; drought; high temperature
Fulltext is available at external website.
Short-term application of elevated temperature and drought influences the isotopic composition of winter wheat grains
The study aimed to determine the differences in carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in grains of three winter wheat varieties grown under optimal and stress conditions. We found ...
Yield formation parameters of winter wheat under two CO2 levels in water sufficient and depleted environment
Hlaváčová, Marcela; Klem, Karel; Veselá, Barbora; Findurová, Hana; Hlavinka, Petr; Smutná, P.; Horáková, V.; Škarpa, P.; Trnka, Miroslav
2021 - English
Agricultural production faces with ongoing climate that in Europe takes form of changing seasonal precipitation pattern with more frequent drought spells. These changes come on top of rising air temperature and did and will affect productivity as well as onset and duration of key developmental stages for yield formation of major staple crops such as wheat. In order to ensure stable agricultural production and satisfy demand of the increasing humanpopulation, it is crucial to know responses of major field crops to these abiotic stress factors to assess suitability of genotypes to specific environmental conditions. The aim of this study was to evaluate final yield formation parameters of five winter wheat genotypes cultivated in pots and exposed to two different levels of CO2 concentrations (400 ppm as ambient and 700 ppm as elevated CO2 concentrations) and two water treatments (well- watered control and drought-stressed plants). Theexperimental treatments were set up in growth chambers from the end of heading stage (BBCH 59)to the beginning of ripening stage (BBCH 71) to simulate the conditions under future climate. The results showed that elevated CO2 concentration led to: (1) mitigation of reduction in final yield formation parameters of drought-stressed plants compared to those of control, (2) enhanced results of drought-stressed treatments compared to those of drought-stressed treatments exposed to the ambient CO2 concentration. Pannonia NS was found out as the less responsive genotype to the exposition of CO2 concentration (no statistically significant differences among ambient and elevated CO2 concentrations in all yield formation parameters were identified). On contrary, harvest index of genotype Bohemia was identified as the most sensitive parameter in response to drought stress as well as to the atmospheric CO2 concentration.
Keywords:
drought stress; elevated co2; triticum aestivum; growth chambe; yield formation parameters
Fulltext is available at external website.
Yield formation parameters of winter wheat under two CO2 levels in water sufficient and depleted environment
Agricultural production faces with ongoing climate that in Europe takes form of changing seasonal precipitation pattern with more frequent drought spells. These changes come on top of rising air ...
Supercritical Impregnation of Natural Extracts in Polymer.
Komárková, Anežka
2021 - English
The vision of this work is to prepare polymeric support loaded with natural extracts and their bioactive compounds in order to create\nwound dressing with anti-inflammatory and anti-bacterial properties. The use of such a dressing may contribute to the wound’s healing\nmechanism by creating a proper physiologic environment, being a barrier for microorganisms and releasing bioactive compounds to the\nwound site.
Keywords:
supercritical impregnation; natural extracts; polymer
Available in a digital repository NRGL
Supercritical Impregnation of Natural Extracts in Polymer.
The vision of this work is to prepare polymeric support loaded with natural extracts and their bioactive compounds in order to create\nwound dressing with anti-inflammatory and anti-bacterial ...
Multiphase Flow of Taylor Bubbles in Rectangular Microchannels.
Regner, Dominik
2021 - English
The aim of this work is to broaden our knowledge of the behavior of Taylor bubbles in a coflowing liquid inside flat microchannels with a high aspect ratio. The primary focus is put on the near-wall region, which is difficult to study both experimentally or numerically. The investigated quantities are the thickness of a liquid film separating the bubble from the microchannel wall, wall shear stress induced by the bubble movement, and the shape and velocity of the translating bubble.
Keywords:
CFD model; rectangular microchannels; bubbles
Available in a digital repository NRGL
Multiphase Flow of Taylor Bubbles in Rectangular Microchannels.
The aim of this work is to broaden our knowledge of the behavior of Taylor bubbles in a coflowing liquid inside flat microchannels with a high aspect ratio. The primary focus is put on the near-wall ...
Solvent Assisted 2D Mesoporous g-C3N4 Modification for Catalytic Application.
Dolai, Susmita
2021 - English
Here we show a facile and scalable new approach for the synthesis of ordered CN materials with an excellent photoactivity, which consists\nof supramolecular interfacial preorganization of monomers at the interface of two non-miscible solvents. Molecular dynamic simulations\nsupported by experimental results reveal that appropriate mono-mers and solvents choice lead to the formation of a supramolecular assembly solely at the interface of the solvents. As a proof of concept, we show the chemical and physical properties of the g-C3N4 materials after thermal condensation in various temperature. The advantages of the new method are demonstrated here through the tuneable morphologies and surface area, the formation of new electronic junctions and high activity as a photocatalyst for hydrogen evolution and pollutants degradation of the g-C3N4 materials.
Keywords:
CN materials; catalyticapplication; absorbance spectra
Available in a digital repository NRGL
Solvent Assisted 2D Mesoporous g-C3N4 Modification for Catalytic Application.
Here we show a facile and scalable new approach for the synthesis of ordered CN materials with an excellent photoactivity, which consists\nof supramolecular interfacial preorganization of monomers at ...
NMR Metabolomics in Toxicology: Effect of NPs Inhalation on Blood Plasma and Exhaled Breath Condensate Profiles.
Michálková, Lenka
2021 - English
In our study, 1H NMR metabolomics was employed to analyse samples of exhaled breath condensate and blood plasma of control subjects and workers before and after the shift where various tasks related to the processing of nanocomposite materials were performed. The main aim of this work is to evaluate the molecular changes induced by NPs inhalation.
Keywords:
NMR metabolomics; toxicology; breath condensate profiles
Available in a digital repository NRGL
NMR Metabolomics in Toxicology: Effect of NPs Inhalation on Blood Plasma and Exhaled Breath Condensate Profiles.
In our study, 1H NMR metabolomics was employed to analyse samples of exhaled breath condensate and blood plasma of control subjects and workers before and after the shift where various tasks related ...
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