MXene exhibits impressive characteristics, including flexibility, mechanical robustness, the capacity to cleanse liquids like water through MXene membranes, water-attracting nature, and effectiveness ...against bacteria. Additionally, bacterial cellulose (BC) exhibits remarkable qualities, including mechanical strength, water absorption, porosity, and biodegradability. The central hypothesis posits that the incorporation of both MXene and bacterial cellulose into the material will result in a remarkable synthesis of the attributes inherent to MXene and BC. In layered MXene/BC coatings, the presence of BC serves to separate the MXene layers and enhance the material’s integrity through hydrogen bond interactions. This interaction contributes to achieving a high mechanical strength of this film. Introducing cellulose into one layer of multilayer MXene can increase the interlayer space and more efficient use of MXene. Composite materials utilizing MXene and BC have gained significant traction in sensor electronics due to the heightened sensitivity exhibited by these sensors compared to usual ones. Hydrogel wound healing bandages are also fabricated using composite materials based on MXene/BC. It is worth mentioning that MXene/BC composites are used to store energy in supercapacitors. And finally, MXene/BC-based composites have demonstrated high electromagnetic interference (EMI) shielding efficiency.
Supramolecular structures based on organized assemblies of macrocyclic chromophores, particularly porphyrin-based dyes, have attracted widespread interest as components of molecular devices with ...potential applications in molecular electronics, artificial light harvesting, and pharmacology. We report the formation of J-aggregates of two porphyrin-based dyes, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TSPP, 4) and an amino tris-sulfonate analogue (5) in water using a functionalized norbornene-based homopolymer, synthesized by ring-opening metathesis polymerization (ROMP). Ionic interactions of the cationic side chains (ammonium groups) of the polymer under acidic conditions with the negatively charged sulfonate groups of the porphyrins facilitated polymer template enhanced J-aggregation of the porphyrin dyes. J-Aggregation behavior was investigated photophysically by UV–vis absorption along with steady-state and time-resolved fluorescence studies. Two-photon absorption (2PA) was enhanced by about an order of magnitude for the J-aggregated TSPP relative to its free base. Significantly, the 2PA cross section of the polymer-templated TSPP J-aggregate was up to three times higher than the J-aggregated TSPP in the absence of the polymer template while the 2PA cross section for polymer-templated J-aggregates of 5 increased substantially, up to ca. 10 000 GM, suggesting a prominent role of polymer-templating to facilitate porphyrin aggregation and greatly enhance nonlinear absorption.
The selective removal of
90
Sr from natural waters and technological effluents is an important issue to ensure radiation safety. Manganese dioxide with layered structure was prepared through the ...reaction of potassium permanganate with manganese chloride in alkaline medium at room temperature. The results of X-ray diffraction method and Fourier transform infrared spectroscopy confirmed the formation of c-disordered hexagonal birnessite. Scanning electron microscopy revealed that the synthesized birnessite is formed as agglomerated microspheres. Scanning electron microscopy and adsorption–desorption method revealed that birnessite is formed as agglomerated microspheres with mesoporous texture and external surface area of 207 m
2
/g. To determine the efficiency of the synthesized birnessite in selective removal of strontium ions from multicomponent solutions, the effect of contact time, competitive ions (Na, K, Ca) and pH on strontium ions adsorption was investigated in detail. Strontium ions adsorption has demonstrated a fast initial adsorption followed by a much slower sorption process. It was found that the synthesized birnessite can effectively remove strontium ions from monocomponent solution. The presence of alkaline metals ions in the model solutions (up to ~ 0.3 mol/l) had little effect on strontium ions adsorption; however, calcium ions caused considerable decrease in the adsorption parameters. However, taking into account a relatively high adsorption parameters obtained in the model solutions characterized by a high concentration of calcium ions and a significant excess of calcium over strontium ions, the synthesized birnessite can be considered as an adsorbent with a rather high selectivity toward strontium ions. It can be effectively applied for the removal of strontium ions from multicomponent solutions with a high salt content. The alkaline medium is preferable for selective removal of strontium ions. The synthesized birnessite has lots of additional advantages, such as its simple fabrication process, low-cost raw materials and the ease of desorption.
A general intravenous anesthetic propofol (2,6-diisopropylphenol) is widely used in clinical, veterinary practice and animal experiments. It activates gamma- aminobutyric acid (GABAa) receptors. ...Though the cerebral cortex is one of the major targets of propofol action, no study of dose dependency of propofol action on cat visual cortex was performed yet. Also, no such investigation was done until now using intrinsic signal optical imaging. Here, we report for the first time on the dependency of optical signal in the visual cortex (area 17/area 18) on the propofol dose. Optical imaging of intrinsic responses to visual stimuli was performed in cats before and after propofol bolus injections at different doses on the background of continuous propofol infusion. Orientation amplitude maps were recorded. We found that amplitude of optical signal significantly decreased after a bolus dose of propofol. The effect was dose- and time-dependent producing stronger suppression of optical signal under the highest bolus propofol doses and short time interval after injection. In each hemisphere, amplitude at cardinal and oblique orientations decreased almost equally. However, surprisingly, amplitude at cardinal orientations in the ipsilateral hemisphere was depressed stronger than in contralateral cortex at most time intervals. As the magnitude of optical signal represents the strength of orientation tuned component, these our data give new insights on the mechanisms of generation of orientation selectivity. Our results also provide new data toward understanding brain dynamics under anesthesia and suggest a recommendation for conducting intrinsic signal optical imaging experiments on cortical functioning under propofol anesthesia.
•Propofol bolus decreases amplitude of optical signal in visual cortex.•The effect of propofol bolus is dose- and time-dependent.•Higher doses produce stronger depression.•Amplitude decreased already during first 12 min after injection.•Suppression at cardinal orientations is more prominent in ipsilateral visual cortex.
The experimental uniaxial cyclic loading diagram for a 40Kh16N9G2S steel specimen was analyzed to define the three sections representing different stress behavior, i.e., three different stress modes. ...For each stress mode, the corresponding evolutionary equations governing anisotropic hardening were formulated. For describing the isotropic hardening, the evolutionary equation for the second-mode saturation parameter is introduced. The stress deviator is defined as the sum of stress deviators of the three modes. The nonlinear damage accumulation is represented by the kinetic equation based on the energy principle, where the energy equal to the work of second-mode stresses within the strain field is taken as the energy spent for damaging of the material. The material functions governing the theory are defined, the basic experiment and the identification method of the material functions are formulated. The material functions of 40Kh16N9G2S steel and theory verification results under proportional strain-controlled cyclic loading and nonproportional loading along the strain path in the form of concentric circles with the common center in the origin of coordinates are presented. Five path turns are examined, starting from the large-curvature path to the mean-curvature one. Computational and experimental results are in close agreement.
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Landsliding is among the most massive and active exogenous processes. Such processes are now occurring more and more actively in permafrost zones due to climate change, and require close attention ...and careful study. Analysis of a territory highly prone to these processes, namely Banks Island, one of the largest islands in northern Canada, confirms earlier studies of landslide processes in this zone, which indicate a relationship between increased activation of landslides and abnormally warm summers. The study and assessment of the landslide focus parameters in the southern part of Banks Island shows that in 1976–1999, the development of landslides was relatively uniform. Nevertheless, after 1999 there was a sharp increase in their size. We identify two types of landslide activation: broad activations in 1999, 2011, 2012, and 2013 with corresponding annual occurrence rates of 20–30 landslides; and occasional (local) activations, with landslides occurring at a rate of 1–2 annually in the intervals between the broad ones. The landslide foci have a random spatial distribution, though these processes take place in particular geological conditions and topography. The largest landslides reach 100 m along the slope and 50 m across the slope. With the help of cluster analysis according to the parameters of the sum of the length and width of landslides, six classes are distinguished, which differ primarily in the intensity and scale of movements. The spatial distribution of landslides by class of behavior in time is even more random than the distribution by year. No new activations after 2015 were identified within the research area. Undoubtedly, the study of the landslide frequency should be continued in the future.
In this paper we demonstrate 3D two-photon recording and two-photon readout in photochromic polymer composites containing a mixture of 1,2-bis(2-methylbenzobthiophen-3-yl)hexafluorocyclopentene ...(diarylethene 1) and fluorene derivatives 2,2‘-(9,9-didecyl-9H-fluorene-2,7-diyl)bis(ethene-2,1-diyl)bis(4,1-phenylene)) dibenzodthiazole (2) or poly(9,9-didecyl-2,7-dipheylaminofluorene) (3). The recording mechanism in this system is based on two-photon excitation of the closed form of diarylethene 1 at 800 nm. The readout mechanism is based on the modulation of the emission intensity of fluorene derivatives 2 or 3 by the closed form of diarylethene 1 through Resonance Energy Transfer (RET). Föster distances (R 0) and critical concentrations (A 0) were calculated from the spectral overlap of the donor's emission (fluorene derivatives) and the acceptor's absorption (closed form of diarylethene 1) in solution and in polymer films of PMMA-co-VBP. This system was demonstrated to be suitable for recording data by two-photon excitation in thick storage media. The RET-based readout method proved to be essentially nondestructive (exhibiting a loss of the initial fluorescence emission less than 20% of the initial emission after 10 000 readout cycles), providing a solution to a long-standing challenge in photochromic optical data storage.
Mathematical simulation of elastoplastic deformation of additionally isotropically hardened materials under proportional and nonproportional cyclic loadings is examined. A rather simple version of ...the plasticity theory, being a special case of the theory of inelasticity, is discussed. This version belongs to the class of single-surface combined-hardening flow theories. The results of computational and experimental investigations of elastoplastic deformation and fatigue fracture of materials at various nonproportional cyclic loads are cited. An adequate description of nonproportional loading processes, additional isotropic hardening effects, as well as fracture processes within one, rather simple version of the plasticity theory is by for the advantage of examined mathematical simulation.
Tuberous sclerosis (TS) is a multi-organ autosomal dominant disorder that is best characterized by neurodevelopmental deficits and the presence of benign tumors. TS pathology is caused by mutations ...in tuberous sclerosis complex (TSC) genes and is associated with insulin resistance, decreased glycogen synthase kinase 3β (GSK3β) activity, activation of the mammalian target of rapamycin complex 1 (mTORC1), and subsequent increase in protein synthesis. Here, we show that extracellular signal-regulated kinases (ERK1/2) respond to insulin stimulation and integrate insulin signaling to phosphorylate and thus inactivate GSK3β, resulting in increased protein synthesis that is independent of Akt/mTORC1 activity. Inhibition of ERK1/2 in Tsc2
cells-a model of TS-rescues GSK3β activity and protein synthesis levels, thus highlighting ERK1/2 as a potential therapeutic target for the treatment of TS.
Detonation nanodiamonds (NDs) were deposited on the surface of aligned carbon nanotubes (CNTs) by immersing a CNT array in an aqueous suspension of NDs in dimethylsulfoxide (DMSO). The structure and ...electronic state of the obtained CNT-ND hybrid material were studied using optical and electron microscopy and Infrared, Raman, X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy. A non-covalent interaction between NDs and CNT and preservation of vertical orientation of CNTs in the hybrid were revealed. We showed that current-voltage characteristics of the CNT-ND cathode are changed depending on the applied field; below ~3 V/µm they are similar to those of the initial CNT array and at the higher field they are close to the ND behavior. Involvement of the NDs in field emission process resulted in blue luminescence of the hybrid surface at an electric field higher than 3.5 V/µm. Photoluminescence measurements showed that the NDs emit blue-green light, while blue luminescence prevails in the CNT-ND hybrid. The quenching of green luminescence was attributed to a partial removal of oxygen-containing groups from the ND surface as the result of the hybrid synthesis.
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