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Amyloid formation is linked with serious human diseases that are currently incurable. Usually, in the study of amyloid aggregation, the description of the protein’s association is in focus. Whereas the mechanism of the cross-β-structure formation, and the presence of aggregation reversibility, remain insufficiently explored. In this work, the kinetics of amyloid aggregation of apomyoglobin (ApoMb) have been studied using thioflavin fluorescence, electron microscopy, and non-denaturing electrophoresis. An analysis of the concentration dependence of the aggregation rates allows the conclusion that ApoMb amyloid formation includes the stages of conformational rearrangements in the aggregates, followed by their association and the fibril formation. The study of the mutant variants aggregation kinetics showed that the association rate is determined by the amino acids’ hydrophobicity, while the rate of conformational rearrangements is affected by the localization of the substitution. An unexpected result was the discovery that ApoMb amyloid formation is reversible, and under native-like conditions, the amyloid can dissociate, producing monomers. A consequence of the reversibility of amyloid aggregation is the presence of the monomer after aggregation completion. Since the aggregation reversibility indicates the possibility of dissociation of already formed fibrils, presented data and approaches can be useful in finding ways for amyloid diseases treatment.

Specific rotation of optically active glycerol analogues, (S)-3-(benzyloxy)propane-1,2-diol [(S)-1], (S)-3-methoxypropane-1,2-diol [(S)-6] and (S)-3-phenoxypropane-1,2-diol [(S)-13], changed its sign from (+) to (–) with increasing concentration in CHCl3, whereas no significant concentration-dependent change was observed in MeOH. The 1H NMR spectrum of (S)-1 showed concentration-dependent changes of the chemical shift in CDCl3. Intermolecular interaction by OH⋯OH hydrogen bonds was suggested by single crystal X-ray crystallography of (S)-13. The concentration-dependent changes of specific rotation of (S)-1, (S)-6, and (S)-13 in CHCl3 can therefore be presumed to be due to self-assembly of these compounds via intermolecular hydrogen bonding at high concentration. The remarkable concentration-dependent changes in specific rotation were also observed to occur in the compounds with related chemical structures, such as (S)-3-hydroxy-4-methoxy-4-oxobutanoic acid [(S)-10], (S)-1-[(2-methylpropan-2-yl)oxycarbonyl]pyrrolidine-2-carboxylic acid [Boc-L-Pro-OH, (S)-14], (R)-3-hydroxy-4,4-dimethylhydrofran-2(3H)-one [(R)-15], (R)-tetrahydrofuran-2-carboxylic acid [(R)-16], (S)-3-methyl-2-[(2-methylpropan-2-yl)oxycarbonylamino]butanoic acid [Boc-L-Val-OH, (S)-17], (R)-oxiran-2-ylmethanol [(R)-18], and (4S)-4-isopropyloxazolidin-2-one [(S)-19]. The existence of intermolecular interaction by C=O⋯HO hydrogen bonds was suggested by single crystal X-ray crystallography of (S)-10, (S)-13, and (S)-14. Thus, this series of chiral compounds have multiple functional groups in appropriate positions that serve as hydrogen-bond donors and/or acceptors, resulting in significant concentration-dependent changes of specific rotation.

Amyloid formation is linked with serious human diseases that are currently incurable. Usually, in the study of amyloid aggregation, the description of the protein's association is in focus. Whereas the mechanism of the cross-β-structure formation, and the presence of aggregation reversibility, remain insufficiently explored. In this work, the kinetics of amyloid aggregation of apomyoglobin (ApoMb) have been studied using thioflavin fluorescence, electron microscopy, and non-denaturing electrophoresis. An analysis of the concentration dependence of the aggregation rates allows the conclusion that ApoMb amyloid formation includes the stages of conformational rearrangements in the aggregates, followed by their association and the fibril formation. The study of the mutant variants aggregation kinetics showed that the association rate is determined by the amino acids' hydrophobicity, while the rate of conformational rearrangements is affected by the localization of the substitution. An unexpected result was the discovery that ApoMb amyloid formation is reversible, and under native-like conditions, the amyloid can dissociate, producing monomers. A consequence of the reversibility of amyloid aggregation is the presence of the monomer after aggregation completion. Since the aggregation reversibility indicates the possibility of dissociation of already formed fibrils, presented data and approaches can be useful in finding ways for amyloid diseases treatment. [ABSTRACT FROM AUTHOR]

Common wisdom holds that ATP hydrolysis is spontaneous because of the weakness of its phosphoanhydride bonds, electrostatic repulsion within the polyanionic ATP4− molecule, and resonance stabilization of the inorganic phosphate and ADP products. By examining the pH‐dependence of the hydrolysis Gibbs free energy, we show that in fact, above pH 7, ATP hydrolysis is spontaneous due mainly to the low concentration of the H+ that is released as product. Hence, ATP is essentially just an electrophilic target whose attack by H2O causes the acidity of the water nucleophile to increase dramatically; the spontaneity of the resulting acid ionization supplies much of the released Gibbs free energy. We also find that fermentation lowers pH not due to its organic acid products (e.g., lactic, acetic, formic, or succinic acids), but again, due to the H+ product of ATP hydrolysis. [ABSTRACT FROM AUTHOR]

This study establishes the existence of substantial agreement between published results from traditional boundary spreading measurements (including synthetic boundary measurements in the analytical ultracenrifuge) on two globular proteins (bovine serum albumin, ovalbumin) and the concentration dependence of diffusion coefficient predicted for experiments conducted under the operative thermodynamic constraints of constant temperature and solvent chemical potential. Although slight negative concentration dependence of the translational diffusion coefficient is the experimentally observed as well as theoretically predicted, the extent of the concentration dependence is within the limits of experimental uncertainty inherent in diffusion coefficient measurement. Attention is then directed toward the ionic strength dependence of the concentration dependence coefficient ( k D ) describing diffusion coefficients obtained by dynamic light scattering, where, in principle, the operative thermodynamic constraints of constant temperature and pressure preclude consideration of results in terms of single-solute theory. Nevertheless, good agreement between predicted and published experimental ionic strength dependencies of k D for lysozyme and an immunoglobulin is observed by a minor adaptation of the theoretical treatment to accommodate the fact that thermodynamic activity is monitored on the molal concentration scale because of the constraint of constant pressure that pertains in dynamic light scattering experiments. [ABSTRACT FROM AUTHOR]

Recent small-angle X-ray scattering (SAXS) for biological macromolecules (BioSAXS) is generally combined with size-exclusion chromatography (SEC-SAXS) at synchrotron facilities worldwide. For SEC-SAXS analysis, the final scattering profile for the target molecule is calculated from a large volume of continuously collected data. It would be ideal to automate this process; however, several complex problems exist regarding data measurement and analysis that have prevented automation. Here, we developed the analytical software MOLASS (Matrix Optimization with Low-rank factorization for Automated analysis of SEC-SAXS) to automatically calculate the final scattering profiles for solution structure analysis of target molecules. In this paper, the strategies for automatic analysis of SEC-SAXS data are described, including correction of baseline-drift using a low percentile method, optimization of peak decompositions composed of multiple scattering components using modified Gaussian fitting against the chromatogram, and rank determination for extrapolation to infinite dilution. In order to easily calculate each scattering component, the Moore-Penrose pseudo-inverse matrix is adopted as a basic calculation. Furthermore, this analysis method, in combination with UV–visible spectroscopy, led to better results in terms of accuracy in peak decomposition. Therefore, MOLASS will be able to smoothly suggest to users an accurate scattering profile for the subsequent structural analysis.

Smart probes (SP) are fluorescent oligonucleotide hairpin probes that are used for the sequence-specific detection of nucleic acids. These probes are able to discriminate between a perfect target and mismatch sequences, which may have sequences very similar to the perfect target sequence. For mismatch sequences very similar to the target of interest, the SP may be unable to discriminate between the perfect target and mismatch sequences due to non-specific hybridization between the SP and mismatch sequences. To prevent such non-specific hybridization, nucleic acid blockers (NABs) are being used to block possible non-specific interactions. However, the concentration dependence of NAB when used for this application has not been clearly established and the appropriate NAB concentration is largely unknown. In this work, we have performed concentration-dependent experiments with NABs in order to establish the appropriate concentration for blocking non-specific SP-mismatch interactions. We mixed the SP with its complementary target in the presence of mismatch sequences and varying concentrations of NABs that are complementary to the mismatch sequences and monitored the resulting fluorescence signal. The fluorescence signal reported by the SP decreases with increasing NAB concentration in an exponential fashion, reaching a limiting NAB concentration of about 500 nM. When used in a complex mixture consisting of SP, target and excess mismatch sequences and NABs, the fluorescence signals slightly decreased, suggesting target–NAB interaction and/or masking effect by the excess NABs. Thus, our results show optimal NAB/SP molar ratio of 10:1, while higher NAB/SP molar ratio can lead to unintended target–NABs interactions and masking effect. [ABSTRACT FROM AUTHOR]

Phosphatidylserine (PS) is an important apoptotic-cell surface signal that exists in bacterial and cancer cells. The mechanism by which melittin interacts with the PS membrane remains unclear. Here, we revealed this mechanism by using a dual-channel fluorescence microscope to observe the concentration-dependent process of pore formation in giant unilamellar vesicles (GUVs) that were exposed to melittin solution. We found that unsaturated PS membranes differed significantly from saturated PS membranes in different phases. This study provides a reference for research and development of anticancer drugs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The RLCDs grafted by –OH groups realized a spectral shift from blue to yellow regions. • The effect of surface chemistry on the aggregation of CDs were further investigated. • RLCDs exhibited excellent solubility and fluorescence properties. • RLCDs could be used to fluorescent anti-counterfeiting and fingerprint tracking and recognition. Achieving the flexible and tunable fluorescence of lignin-based N-doped carbon dots (LCDs) remains a win–win yet challenging strategy. In this study, combining the surface engineering and concentration regulation strategy enabled the flexible adjustment of LCDs fluorescence emission from blue to yellow regions (345 to 560 nm). The surface electron-donor –OH groups not only enhanced the photoluminescence quantum yield (PLQY) to 14.75 % but activated the spectral shift of reduced LCDs (RLCDs). These arose from the reinforced π-electron conjugation and generated new –OH-related extrinsic defects with elevating concentration. Conversely, the electron-withdrawing C O groups participated in the blue-to-green fluorescence modulation. Still, they drastically reduced the PLQY of oxidized LCDs (OLCDs) to 2.13 %, due to the larger particle size and more non-radiative transfer induced by C O groups. Based on these, CDs/PVA films and printed fluorescent patterns with multicolor fluorescence were realized for anti-counterfeiting, and the RLCDs@Al 2 O 3 hybrid facilitated the precise fluorescence fingerprint tracking and recognition. This study provided a facile strategy for enriching and developing novel LCDs with flexible fluorescence for their advanced applications. [ABSTRACT FROM AUTHOR]

This work concerns the concentration dependence of the optical properties of microscale samples according to the solid solution Li2Ca1–2 x Pr x Na x SiO4 with x = 0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.07, and 0.1. Phase purity was inspected by using X-ray powder diffraction. In order to figure out concentration dependent similarities and differences of their properties with respect to down- and up-conversion, luminescence spectroscopy for vacuum UV (VUV), X-ray, and blue light excitation were performed. Furthermore, diffuse reflection spectroscopy as well as time dependent luminescence measurements were conducted. It turns out that the concentration quenching of the up-conversion lags the down-conversion. In addition, a rise time can be observed in the time dependent measurements of the up-conversion. From these observations, it is concluded that the up-conversion process takes place via an energy transfer process with a very high probability. Up-conversion particles convert visible light into UV-C radiation upon illumination. The obtained UV spectrum is capable of inactivating exposed microorganisms. If particles are in the shade, UV radiation is no longer generated, which means that the user is not exposed to harmful UV radiation. [ABSTRACT FROM AUTHOR]

This work concerns the concentration dependence of the optical properties of microscale samples according to the solid solution Li2Ca1–2 x Pr x Na x SiO4 with x = 0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.07, and 0.1. Phase purity was inspected by using X-ray powder diffraction. In order to figure out concentration dependent similarities and differences of their properties with respect to down- and up-conversion, luminescence spectroscopy for vacuum UV (VUV), X-ray, and blue light excitation were performed. Furthermore, diffuse reflection spectroscopy as well as time dependent luminescence measurements were conducted. It turns out that the concentration quenching of the up-conversion lags the down-conversion. In addition, a rise time can be observed in the time dependent measurements of the up-conversion. From these observations, it is concluded that the up-conversion process takes place via an energy transfer process with a very high probability. Up-conversion particles convert visible light into UV-C radiation upon illumination. The obtained UV spectrum is capable of inactivating exposed microorganisms. If particles are in the shade, UV radiation is no longer generated, which means that the user is not exposed to harmful UV radiation. [ABSTRACT FROM AUTHOR]

An analysis of our data on 1H and 13C spin–lattice and spin–spin relaxation times and rates in aqueous suspensions of purified nanodiamonds produced by detonation technique (DNDs), DNDs with grafted paramagnetic ions, and micro- and nanodiamonds produced by milling bulk high-temperature high-pressure diamonds is presented. It has been established that in all the studied materials, the relaxation rates depend linearly on the concentration of diamond particles in suspensions, the concentration of grafted paramagnetic ions, and surface paramagnetic defects produced by milling, while the relaxation times exhibit a hyperbolic dependence on the concentration of paramagnetic centers. This is a universal law that is valid for suspensions, gels, and solids. The results obtained will expand the understanding of the properties of nano- and microdiamonds and will be useful for their application in quantum computing, spintronics, nanophotonics, and biomedicine. [ABSTRACT FROM AUTHOR]

Carbon nanodots (CNDs) exhibiting concentration dependent properties have been synthesized through a one-pot hydrothermal reaction process utilizing diethylenetriamine and l-aspartic acid. At solid-state or high concentrations, the CNDs display excitation-wavelength independent fluorescence (FL) emissions, while at low concentrations, they exhibit excitation-wavelength dependent FL emissions. Detailed characterization of the structure and optical properties reveals that the concentration dependent FL properties can be ascribed to the intrinsic-state luminescence of the CNDs at low concentrations and the assembled-state luminescence at solid-state/high concentrations. With the increase of concentration, the self-assembly behavior of CNDs may cause the transition from intrinsic-state dominant luminescence to assembled-state dominant luminescence, and finally lead to the red-shift of FL color. Furthermore, the CNDs@Urea composites possess adjustable room-temperature phosphorescence (RTP) from turquoise to yellow by controlling the CNDs doping concentration. CNDs with concentration dependent optical properties have shown certain potentials in the fields of cell imaging, fingerprint recognition and anti-counterfeiting applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The rheological properties of electrode slurry are mainly influenced by the concentration, which further affects the Lithium-ion batteries (LIBs) quality and manufacturing processes. In this work, various methods including steady-state shear, creep, rheological model fitting, hysteresis loop, and small amplitude oscillatory shear (SAOS) measurement were employed to investigate the concentration-dependent rheological behaviors of slurry, in particular its yield stress, thixotropy, and viscoelasticity. Results show that the difference in yield stress obtained from varying methods is observed, in which the yield stresses measured by the SAOS test are closer to the steady-state value due to its advantage that non-destructive property at small deformations only causes minimum disturbance. The improvement of slurry concentration enhances the bonding strength between particles, thereby resulting in an increase of yield stress and thixotropy, and a decrease of the time scale of transient behavior during the creep process. In oscillatory shear measurement, both storage and loss modulus are concentration-dependent, while yielding and strain stiffening corresponding to critical strains exhibit concentration-independent. In addition, the increase in concentration leads to a more pronounced strain stiffening behavior and a lower characteristic frequency as well as a longer relaxation time. Understanding the relationship between concentration and rheological behaviors will be helpful for material design, preparation, and production in different stages. [ABSTRACT FROM AUTHOR]

Calculation results regarding the concentration dependence of the electrical transfer parameters of resistivity, mean free path and Fermi energy for high-entropy alloys HEA (number of components from 4 to 6) in the form of film or bulk alloys are presented. Calculations were made assuming the additivity of parameters: ρ = ∑n i=1 ciρi, λ-1 = ∑n i=1 ciλ-1i and εF = ∑n i=1 ciεFi is the resistivity; λ is the mean free path of electrons; εF is the Fermi energy), which in the case of resistivity is confirmed experimentally. Based on the obtained results and analysis of the Fermi surface form for HEA, a qualitative conclusion is made regarding the fact that studied in the work HEA should not be classified as new substances, since they are one of the types of metallic solid solutions with electronic parameters close in magnitude to metals. [ABSTRACT FROM AUTHOR]

This project is focused on the experimental determination of the specific heat capacity of aqueous solutions of LiCl with different mass concentrations as a function of temperature. A new laboratory method for its measurement has been proposed, which is applicable for various liquids and, in contrast to calorimetry, relies on the heat transfer between two media with different temperatures and thus accounts for the heat losses of this thermodynamic system. A theoretical model based on the heat balance equation for Newtonian and Stephan-Boltzmann heat transfer has been constructed. Laboratory experiments have been carried out using aqueous solutions of LiCl with mass concentration ranging from 0 to 15% and at temperatures in the range 20-90 ℃. The data has been analysed using MATLAB and empiric equations for the temperature dependence of the specific heat capacity for fixed mass concentrations of the solute have been obtained. The results are in good agreement with the reference values. [ABSTRACT FROM AUTHOR]

We study the phase-field model with the elasticity energy arising from the coherency stress across the two-phase interface for lithium-ion batteries by using olivine LiFePO4 as a model system. The existence of global solutions about this model which is a coupled system of elliptic and parabolic equations with the singular points in the case of a logarithmic nonlinear term p (c) is proved. We demonstrate the model satisfies the second law of thermodynamics, and numerical simulations are given to show that the evolution of lithium concentration and the motion of interfaces are consistent with the experiments results of Laffont et al. [ABSTRACT FROM AUTHOR]

Supramer analysis was applied to explain the earlier discovered phenomenon of the transformation of nonselective glycosylation into stereospecific one upon changing the glycosyl donor concentration. The supramer analysis is a part of the supramer approach being developed by us and makes it possible to find concentration ranges separated by "critical" concentrations at which supramolecular aggregates (supramers) have different structures. As a result, the "critical" concentration for solutions of 2,3,5-tri-O-benzoyl-α-d-arabinofuranosyl bromide (1) in acetonitrile was found by polarimetry, and that for solutions of glycosyl bromide 1 in 1,2-dichloroethane (DCE) was found using static light scattering. The presence of nanosized supramers in solutions of 1 in acetonitrile and nano- and mesoscale supramers in solutions of 1 in DCE was demonstrated using dynamic light scattering. An analysis of the obtained experimental and earlier published data suggested a possibility of both formation of halogen bonds involving DCE molecules and halogen bond-mediated supramolecular aggregation of molecules of the dissolved substance in this solvent. [ABSTRACT FROM AUTHOR]

Abscisic acid (ABA) plays an important role in the regulation of protective processes under stresses of various nature. In contrast to abiotic stresses, when a plant and a pathogen interact, this phytohormone is in most cases a negative regulator of resistance. However, even with a similar nature of pathogenesis, ABA can produce different effects. For example, ABA treatment in different experiments induced either a decrease or an increase in the susceptibility of cereals to powdery mildew. The aim of this work was to study the immunomodulatory properties of exogenous ABA depending on its concentration in the pathosystem composed of wheat Triticum aestivum L. plants and powdery mildew pathogen Blumeria graminis (DC.) Speer f. sp. tritici (syn. Erysiphe graminis). We studied the change in the number of pathogen colonies on susceptible wheat leaves (Zarya and Tavrichanka varieties) when two-week-old seedlings were treated with various ABA concentrations (0–9 μM) before and immediately after they were infected. When whole plants were used in the experiment, ABA was added to Knop’s solution; in experiments with detached leaves floating in Petri dishes, aqueous solutions of the phytohormone were used. Our results show that the magnitude and direction of the effect of exogenous ABA on the number of colonies of the pathogen depends on its concentration and the time of application relative to the moment of infection. ABA concentration dependence was variable in form: similar concentrations could be inhibitory, resulting in the minimum number of colonies, or stimulating, with the maximum number of colonies. At the same time, the pre-infection use of ABA was more likely to be inhibitory. The non-monotonicity and variation of the form of concentration dependence could probably account for the contradictory literature data on the immunomodulatory properties of ABA. The complex nature of the concentration dependence and the corresponding variation in the immunological state within a fairly wide range seem to ensure the Abscisic acid (ABA) plays an important role in the regulation of protective processes under stresses of various nature. In contrast to abiotic stresses, when a plant and a pathogen interact, this phytohormone is in most cases a negative regulator of resistance. However, even with a similar nature of pathogenesis, ABA can produce different effects. For example, ABA treatment in different experiments induced either a decrease or an increase in the susceptibility of cereals to powdery mildew. The aim of this work was to study the immunomodulatory properties of exogenous ABA depending on its concentration in the pathosystem composed of wheat Triticum aestivum L. plants and powdery mildew pathogen Blumeria graminis (DC.) Speer f. sp. tritici (syn. Erysiphe graminis). We studied the change in the number of pathogen colonies on susceptible wheat leaves (Zarya and Tavrichanka varieties) when two-week-old seedlings were treated with various ABA concentrations (0–9 μM) before and immediately after they were infected. When whole plants were used in the experiment, ABA was added to Knop’s solution; in experiments with detached leaves floating in Petri dishes, aqueous solutions of the phytohormone were used. Our results show that the magnitude and direction of the effect of exogenous ABA on the number of colonies of the pathogen depends on its concentration and the time of application relative to the moment of infection. ABA concentration dependence was variable in form: similar concentrations could be inhibitory, resulting in the minimum number of colonies, or stimulating, with the maximum number of colonies. At the same time, the pre-infection use of ABA was more likely to be inhibitory. The non-monotonicity and variation of the form of concentration dependence could probably account for the contradictory literature data on the immunomodulatory properties of ABA. The complex nature of the concentration dependence and the corresponding variation in the immunological state within a fairly wide range seem to ensure the

Dielectric properties of composites based on planar-oriented 6СВ liquid crystal with Cu6PS5X (X = I, Br) nanoparticles at 293 K in the frequency range from 6 to 106 Hz have been studied. The concentration of nanoparticles varied from 0 up to 0.1 wt.%. It has been shown that Сu6PS5Вr nanoparticles significantly less influence the conductivity of 6CB than the Сu6PS5I nanoparticles. Moreover, at the concentrations 0.01 to 0.05 wt.% of Cu6PS5Br nanoparticles the conductivity of LC decreases. It has been assumed that the nonmonotonic dependence of 6CB conductivity on the concentration of Cu6PS5Br super-ionic nanoparticles is caused by two competing mechanisms: an increase in conductivity due to the introduction of conductive impurities with nanoparticles and a decrease in conductivity caused by adsorption of impurities on the surface of nanoparticles.

Gel polymer electrolytes (GPEs) represent a credible alternative to organic liquid electrolytes (LEs) for safer sodium metal batteries. As a compromise between solid polymer electrolytes and LEs, GPEs ensure a good ionic conductivity, improve the electrolyte/electrode interface, and prevent solvent leaks. Herein, a GPE based on acrylate-bifunctionalized polyethylene glycol chains mixed with an ether solvent (TEGDME) and a polyethylene glycol diacrylate (PEG600DA) in a 50/50 wt % ratio was prepared by ultraviolet photopolymerization. Sodium bis(fluorosulfonyl)imide salt (NaFSI) was added at different concentrations to study its interactions with the solvent and/or the cross-linked polymer. Infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and swelling ratio characterizations were combined to determine the physicochemical properties of the GPE. Complementary characterizations including electrochemical impedance spectroscopy, chronopotentiometry, and cyclic voltammetry allowed correlating the physicochemical properties of the GPE to its electrochemical performance. Then, improvements were obtained by careful combination of its components. The cross-linking agent allowed us to obtain a polymer matrix that traps the organic solvent and prevents leakage. Such a solvent inclusion reduces the rigidity of the membrane and lowers its viscosity, offering a room temperature ionic conductivity of 4.8 × 10 -4 Ω -1 cm -1 . The control of polymer's tortuosity leads to a stable cycling vs sodium metal over several hundred hours without increase of the polarization. Finally, optimization of the salt loading plays a major role in electrostatic cross-linking, leading to an improvement of the mechanical properties of the GPE without reducing its conductivity.

An analysis of our data on 1H and 13C spin–lattice and spin–spin relaxation times and rates in aqueous suspensions of purified nanodiamonds produced by detonation technique (DNDs), DNDs with grafted paramagnetic ions, and micro- and nanodiamonds produced by milling bulk high-temperature high-pressure diamonds is presented. It has been established that in all the studied materials, the relaxation rates depend linearly on the concentration of diamond particles in suspensions, the concentration of grafted paramagnetic ions, and surface paramagnetic defects produced by milling, while the relaxation times exhibit a hyperbolic dependence on the concentration of paramagnetic centers. This is a universal law that is valid for suspensions, gels, and solids. The results obtained will expand the understanding of the properties of nano- and microdiamonds and will be useful for their application in quantum computing, spintronics, nanophotonics, and biomedicine.

Arbuscular mycorrhizal fungi (AMF) play an important role in improving plant tolerance and accumulation of zinc (Zn) and cadmium (Cd). The growth, physiology and absorption of elements and transport in Phragmites australis (P. australis) were investigated under Zn and Cd stress to identify the transport mechanisms of toxic trace elements (TE) under the influence of AMF. Thus, AMF were observed to alleviate the toxic effects of Zn and Cd on P. australis by increasing plant biomass and through different regulatory patterns under different TE concentrations. The activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) increased under Zn stress, and the activities of SOD, catalase (CAT), peroxidase (POD), and APX significantly increased under high concentrations of Cd. AMF differ in their strategies of regulating the transport of different metals under TE stress. Under Zn stress, the concentration of Zn in P. australis decreased by 10–57%, and the effect on Zn translocation factor (TFZn) was concentration-dependent. AMF increased the TFZn under low concentration stress, but decreased under high concentration stress. Under Cd stress, the concentration of Cd increased by as much as 17–40%, and the TFCd decreased. AMF were also found to change the interaction of Zn×Cd. In the absence of AMF, Cd exposure decreased the Zn concentrations in P. australis at Zn100 mg/L and Zn300 mg/L, while it increased the contents of Zn at Zn700 mg/L. The opposite trend was observed following treatment with AMF. However, regardless of the concentration of Cd, the addition of Zn decreased the concentration of Cd in both treatments in both the presence and absence of AMF. Under different TE stress conditions, the regulation of metal elements by AMF in host plants does not follow a single strategy but a trade-off between different trends of transportations. The findings of our study are important for applying AMF-P. australis systems in the phytoremediation of Zn-Cd co-contaminated ecosystems.

This retrospective investigation has established that the early theoretical attempts to directly incorporate the consequences of radial dilution into expressions for variation of the sedimentation coefficient as a function of the loading concentration in sedimentation velocity experiments require concentration distributions exhibiting far greater precision than that achieved by the optical systems of past and current analytical ultracentrifuges. In terms of current methods of sedimentation coefficient measurement, until such improvement is made, the simplest procedure for quantifying linear s-c dependence (or linear concentration dependence of 1/s) for dilute systems therefore entails consideration of the sedimentation coefficient obtained by standard c(s), g*(s) or G(s) analysis) as an average parameter ( s ¯ ) that pertains to the corresponding mean plateau concentration (following radial dilution) ( c ¯ ) over the range of sedimentation velocity distributions used for the determination of s ¯ . The relation of this with current descriptions of the concentration dependence of the sedimentation and translational diffusion coefficients is considered, together with a suggestion for the necessary improvement in the optical system. [ABSTRACT FROM AUTHOR]

Osmosis is the natural flow of a solvent through a semi-permeable membrane from a less concentrated solution to a more concentrated one. This is driven by the osmotic pressure difference. If opposing external pressure is used that exceeds the osmotic pressure, the solvent will flow from the more concentrated solution towards the less concentrated one. Besides the external pressure, the flux of the solvent (water) describing the reverse osmosis is the function of the osmotic pressure, which, in the case of an ideal solution, according to the van’t Hoff principle, is proportional to the salt concentration. The current study examines the concentration dependence of the permeate flux, complementing the traditional model with the osmotic pressure difference caused by the concentration polarization stemming from the crossflow. In the calculations for the real solution, the osmotic coefficient was used instead of the empirical forms of osmotic pressure, making the model more correct theoretically as well. The validity of the model was certified and the parameters determined with independently measured results based on literature regarding the reverse osmotic desalination of seawater. [ABSTRACT FROM AUTHOR]

We have derived effective potentials of Na+ and Cl— ions in implicit water at temperatures from 273 to 340 K and concentrations between 0,3 and 1 M. We divide the potentials into two parts: slowly decreasing Coulomb function and solvation energy. The primary dependence of the effective potentials on the parameters proved to be in the dependence on them of the dielectric constant. Slight temperature dependence of the solvation is present for the pairs Na+ — Na+ and Na+ — Cl— only.

In this work, by combining conformational isomeric moiety to MR-emitting core, we propose a new pathway to reduce the concentration sensitivity without compromising color purity of MR-TADF emitters. [Display omitted] • Two novel MR-TADF emitters with conformational isomerism were designed. • Conformational isomerism is introduced to deal with poor concentration dependence. • Concentration quenching can be suppressed with barely harming color purity. • BNCz-aDMAC-based OLEDs achieve superior performance with low concentration dependence. Electroluminescent performance of multiple resonance (MR) type thermally activated delayed fluorescence (TADF) emitters is highly dependent to the doping concentration due to the flat molecular structures, which is a major issue toward practical applications. Herein, an effective approach reducing the concentration dependence is proposed by introducing conformational isomerism for MR-TADF emitters. Two novel MR-TADF emitters were designed by decorating 10H-spiro[acridine-9,2′-adamantane] (a-DMAc) as a dual-conformational moiety onto the MR-core BNCz with different connection methods, which could induce different conformational distributions. In particular, the conformational isomerism of BNCz-aDMAC leads to a lower fraction of QE forms compared to the QE-dominant BNCz-PDMAC in amorphous doped film states with identical doping weights, thus enabling effective suppression of concentration quenching with barely harming color purity. Therefore, BNCz-aDMAC-based organic light-emitting diodes (OLEDs) demonstrate consistent and high efficiency over a wide doping range, maintaining a maximum external quantum efficiency of 23.8 % and a full width at half maximum of 31 nm even at a high doping ratio of 30 wt%. [ABSTRACT FROM AUTHOR]

On the bases of thermodynamic model we have obtained the ratio for the bond energy of alloy crystals. The modified electron-statistical method has reproduced size and concentration dependences of the surface energy of thin films of the transitional metal alloys.

Dielectric properties of composites based on planar-oriented 6СВ liquid crystal with Cu6PS5X (X = I, Br) nanoparticles at 293 K in the frequency range from 6 to 106 Hz have been studied. The concentration of nanoparticles varied from 0 up to 0.1 wt.%. It has been shown that Сu6PS5Вr nanoparticles significantly less influence the conductivity of 6CB than the Сu6PS5I nanoparticles. Moreover, at the concentrations 0.01 to 0.05 wt.% of Cu6PS5Br nanoparticles the conductivity of LC decreases. It has been assumed that the nonmonotonic dependence of 6CB conductivity on the concentration of Cu6PS5Br superionic nanoparticles is caused by two competing mechanisms: an increase in conductivity due to the introduction of conductive impurities with nanoparticles and a decrease in conductivity caused by adsorption of impurities on the surface of nanoparticles. [ABSTRACT FROM AUTHOR]

• The film phased state does not depend on the Ag concentration. • Different types of magnetoresistive effect was observed. • The maximum value of isotropic MR observed at the addition of Ag with c = 60 at.%. • Temperature dependences of LMR and TMR in the range from 300 to 900 K are presented. Comprehensive investigation of the phase state and the magnetoresistive properties of Ag-added Ni 80 Fe 20 film systems with a total thickness of 55 nm in a wide range of component concentration under the heat treatment within the temperature range 300–900 K was presented. Thin films based on permalloy Ni 80 Fe 20 with addition of Ag atoms were prepared by the electron-beam co-evaporation method at room temperature. Their composition and phase state were studied using X-ray spectrometry and electron diffraction methods. The film phased state remained unchanged when adding Ag within the entire range of investigated compositions. The process of the high-temperature treatment also did not affect their structure. Different types of magnetoresistive effect were observed. The anisotropic magnetoresistive effect appeared in systems with low concentration of Ag atoms. With increasing concentration of the non-magnetic atoms the shape of magnetoresistive field dependences transformed to the linear-like drop curves without hysteresis that led to the appearance of the isotropic magnetoresistive effect in the film plane. The maximum isotropic magnetoresistance was observed at the Ag concentration of about 60 at.%. The magnitude of this maximum value increased after annealing at 500 K and significantly reduced after high-temperature annealing at 900 K. [ABSTRACT FROM AUTHOR]

Triplet-level population distributions of organic molecules in glassy matrices were studied by computer simulation for various exciting-light intensities and compound concentrations. The dependence of the triplet-level population distribution on these variables was found. A consequence of the established relationship was that the exciting-light intensity affected the concentration dependence of the luminescence intensity where the population change of the molecular ground state resulting from their transition into the triplet state could not be neglected. [ABSTRACT FROM AUTHOR]

Alumina ceramics doped with a different concentration of magnesium and manganese were synthesized at a different annealing temperature and medium. An increase in the dopant concentration leads to an increase in the pulsed cathodoluminescence intensity of impurity centers at 515 nm (Mg) and 678 nm (Mn). The concentration quenching of the luminescence in the 678 nm band occurs for Al 2 O 3 :Mn ceramics. The dopants affect the luminescence intensity in the F-center band differently. An increase in the concentration of an impurity from 0.001 to 18.77 wt % in Al 2 O 3 :Mn ceramics leads to a 4-fold decrease in the luminescence intensity of the F-center. On the other hand there is a maximum of the luminescence intensity of the F-center for Al 2 O 3 :Mg ceramics with a dopant concentration of 1 wt %. The luminescence bands of Cr3+ (687 nm) and most likely F-centers (670 nm) are dominated depending on the excitation energy in photoluminescence spectra of both Al 2 O 3 :Mg and Al 2 O 3 :Mn ceramics. The low luminescence intensity of the magnesium band (750 nm) is detected upon the excitation in the band of 325 nm. The luminescence bands of Mn2+ (540 nm) and Mn4+ (650 nm) with low intensity are found in the photoluminescence spectrum too. • The concentration quenching of the luminescence occurs for Al 2 O 3 :Mn ceramics. • A Mn concentration growth leads to a 4-fold decrease in a PCL intensity of F-center. • There is a maximum of the luminescence intensity of the F-center at 1 wt % of Mg. • The PL bands at 670 and 687 nm are dominated for Mg- and Mn-doped alumina ceramics. [ABSTRACT FROM AUTHOR]

Abstract To clarify the concentration dependence of visible fluorescence of Pr3+, a series of phosphate glass samples with Pr3+ concentration from 0.05 to 3.0 mol% were fabricated. Steady and dynamic spectroscopic characteristics of Pr3+-doped phosphate glasses were systematically investigated. When the Pr3+ concentration was small, only one visible fluorescence band can be observed at 596 nm, which was ascribed to the transition of 1D 2 → 3H 4. With increasing Pr3+ concentration from 0.05 to 0.5 mol%, since the multi-phonon relaxation rate of 3P 0 was largely quicker than that of 1D 2. Increasing Pr3+ concentration from 0.5 to 3 mol%, increasing two other fluorescence bands at 612 nm and 640 nm, which were assigned to the transitions of 3P 0 → 3H 6 and 3P 0 → 3F 2 , respectively. It was due to the cross relaxation probability between [1D 2 : 1G 4 ] and [3H 4 : 3F 4 ] increased, which results in quicker decay rate of 1D 2. The fluorescence lifetime of 1D 2 decreased from 173 to 6 μs with increasing Pr3+ concentration from 0.1 to 3 mol%, which due to the cross relaxation probability between [1D 2 : 1G 4 ] and [3H 4 : 3F 4 ] increased, resulting in quicker decay rate of 1D 2. Fitting the concentration dependence of fluorescence lifetime demonstrated that the cross relaxation arising from dipole-dipole interactions between Pr3+ ions. Graphical Abstract (a) Fluorescence spectra of 0.1 mol% and 3.0 mol% Pr3+-doped phosphate excited at 467 nm; (b) decay curves of 1D 2 for 0.1 mol% and 3.0 mol% Pr3+-doped phosphate; (c) concentration dependence of fluorescence lifetime and corresponding the fitting curve; (d) energy diagram and cross relaxation process between Pr3+ ions. Unlabelled Image Highlights • Clarify concentration dependence of visible emission behaviors of Pr3+ in phosphate glasses. • Clarify the multiphonon relaxation processes of Pr3+ in phosphate glasses. • Clarify the mechanism of the cross relaxation process between Pr3+ ions in phosphate glasses. [ABSTRACT FROM AUTHOR]

Multi-emission carbon dots (M-CDs) have broad applications. However, reports of the synthesis of M-CDs and their emission mechanism are limited. In this study, M-CDs with three emissions are synthesized by a one-pot solvothermal method, and the luminescence mechanism is investigated in detail. The prepared M-CDs show significant concentration-dependent properties. For high-concentration M-CDs (HC CDs) , the surface-defect and carbon-core luminescence states are related to emission centers at 423 and 586 nm, respectively. The emission center at 493 nm are mainly due to the self-absorption of M-CDs. Conversely, low-concentration M-CDs (LC CDs) have 423 and 586 nm emissions. The blue CDs (B-CDs) and red CDs (R-CDs) are extracted from the prepared M-CD solution. The structural and optical properties indicate that the 493 nm peak is related to aggregation and self-absorption between B-CDs and R-CDs in HC CDs. Surprisingly, solid CDs (S-CDs) with solid-state room-temperature phosphorescence (RTP) are simultaneously obtained during the preparation of the M-CDs. The mechanism investigation results show that S-CDs are composed of CDs and NaHCO 3 , and NaHCO 3 acts as an oxygen barrier to prevent the quenching of the triplet and rigidly holds the luminescent guests to suppress vibrational dissipation. The M-CDs are successfully applied to detect Morin, while the S-CDs are demonstrated for optical anti-counterfeiting applications. • For the first time, M-CDs and S-CDs produced simultaneously with a one-pot method. • M-CDs with three emission peaks showed concentration dependent fluorescence. • CDs emitting in the blue and red regions were extracted from the M-CDs mixture. • The fluorescence and phosphorescence mechanisms are discussed in detail. • Morin detection and optical anti-counterfeiting applications were demonstrated. [ABSTRACT FROM AUTHOR]

Abstract The present work is devoted to understand the probe and surfactant concentration dependence of solvation dynamics in sodium dodecyl sulfate (SDS) micelle. The average solvation times are found to follow the hydrophobicity of the probe and it was concluded that the location of probe inside SDS micelle determines the solvation time. We also studied the solvation dynamics in varying concentrations of SDS in water and found a small but definite increasing trend in solvation time. Rotational diffusion time of the fluorescent probe did not change with change in SDS concentration, which hinted that distortion in the shape of micelle may be the reason behind variation of solvation time. The analysis of solvent response function in all the cases hints towards the existence of an ultrashort (∼100 fs) time component due to the libration motion of water molecules. [ABSTRACT FROM AUTHOR]

The concentration dependences of the adhesive strength, τ, of joints of 150 µm diameter steel wire and modified epoxy binder were investigated. The modifier used was PSK-1 polysulphone of different molecular weight, M. The concentration, C, of PSK-1 was varied from 5 to 20 wt%. It was shown that the form of the τ-C curves changes with change in M. At M = 5000 and 10 000, τ is not dependent on C; at M = 17 000 and 27 000, the τ-C relationship is described by a curve with a maximum. At M = 35 000 and 42 000, the adhesive strength decreases with increase in C. The factors affecting the measured value of τ in the case of epoxides modified with heat-resistant thermoplastics are considered. [ABSTRACT FROM AUTHOR]

The accuracy with which the concentration dependence of the sedimentation coefficient, s = s0(1 − kc), can be quantified for globular proteins by commonly used procedures has been examined by subjecting simulated sedimentation velocity distributions for ovalbumin to c(s)‒s analysis. Because this procedure, as well as its g(s)‒s counterpart, is based on assumed constancy of s over the time course of sedimentation coefficient measurement in a given experiment, the best definition of the concentration coefficient k is obtained by associating the measured s with the mean of plateau concentrations for the initial and final distributions used for its determination. The return of a slightly underestimated k (by about 3%) is traced to minor mislocation of the air‒liquid meniscus position as the result of assuming time independence of s in a given experiment. Although more accurate quantification should result from later SEDFIT and SEDANAL programs incorporating the simultaneous evaluation of s0 and k, the procedures based on assumed constancy of s suffice for determining the limiting sedimentation coefficient s0—the objective of most s‒c dependence studies. [ABSTRACT FROM AUTHOR]

This review summarizes endeavors undertaken in the middle of last century to employ the Lamm equation for quantitative analysis of boundary spreading in sedimentation velocity experiments on globular proteins, thereby illustrating the ingenuity required to achieve that goal in an era when an approximate analytical solution of that nonlinear differential equation of second order provided the only means for its application. Application of procedures based on that approximate solution to simulated sedimentation velocity distributions has revealed a slight disparity (about 3%) between returned and input values of the diffusion coefficient—a discrepancy comparable with that of estimates obtained by current simulative analyses based on numerical solution of the Lamm equation. Although the massive technological developments in the gathering and treatment of sedimentation velocity data over the past three to four decades have changed dramatically the manner in which boundary spreading is analyzed, they have not led to any significant improvement in the accuracy of the diffusion coefficient thereby deduced. [ABSTRACT FROM AUTHOR]

The results of investigation strain properties (integral (yi)int and differential (yi)dif strain coefficients) of thin film nanostructures based on permalloy Ni8oFe20 (Ру) silver (Ag), prepared by method of coevaporation from independent sources, and results for components of the systems are presented. The main peculiarities of Py and Ag strain properties in the range of thicknesses d = 10-60 nm are determinate. It has been shown that the maximum at the CAg = 30-36 at.% is observed at the concentration dependences of (yi)int. The presence of a maximum is due to the structural changes in the film systems. [ABSTRACT FROM AUTHOR]