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In this work we argue that the reverse martensitic transformation (MT) of the stress-induced martensite (SIM) of Fe–Mn–Si-based alloys for moderate prestrains occurs in essentially thermoelastic-like way, in contrast to non-thermoelastic MT of temperature-induced martensite (TIM). We compare, using a number of complementary experimental techniques, the temperatures and the kinetics of the reverse ε→γ martensitic transformation of SIM and TIM for commercial and model Fe–Mn–Si alloys after various thermomechanical treatments. We claim that two studied phenomena are generic in Fe–Mn–Si-based alloys of different compositions and microstructure: first, opposite to the conventional effect of stabilization of martensite by prestrain, the reverse MT during heating of alloys prestrained in bending and tension starts well below (up to 100 K) the start temperature of the reverse MT for the TIM of the same alloy. The difference between engineering temperatures of the start of the reverse transformation, As, for SIM and TIM reaches ca. 50 K, pointing to a need to consider different As for TIM and SIM, AsTIM and AsSIM. Second, the reverse transformations of TIM and SIM show very different kinetics. The reverse MT of SIM is diffuse over the temperature range exceeding 100 K. The reverse MT of TIM, on the contrary, is well localized within the temperature range of ca. 20 K. The experimental observations can be interpreted assuming that, due to the differences in the formation mechanisms of SIM and TIM, the latter shows non-thermoelastic behaviour, whereas the SIM shows similarities with the thermoelastic martensites stabilized by prestrain.

Introduction. Resonators based on epitaxially grown single-crystal films of yttrium iron garnet are used in various applications of microwave electronics. It is known that with increasing of microwave power incident on a resonator, various nonlinear effects begin to manifest themselves. There are: bistability effect, nonlinear frequency shift, nonlinear damping, etc. By now, the listed nonlinear effects have been quite good studied experimentally. Previously, when describing oscillations of various dynamical systems, the nonlinear damping and the nonlinear frequency shift were usually considered separately. At the same time, it was known that, when studying nonlinear magnetization oscillations in ferromagnetic film resonators with an increase in oscillation amplitude, these effects could occur simultaneously.Aim. Development of a model of magnetization oscillations taking into account the nonlinear frequency shift and nonlinear damping, as well as its experimental justification for a ferromagnetic film resonator.Materials and methods. The development of the model was carried out by the method of slowly varying amplitudes. An experimental study was carried out with a ferromagnetic film resonator. For the measurements, we used Rohde & Schwarz ZVA 40 vector network analyzer. We measured the frequency dependence of the reflection coefficient of the microwave signal from the resonator.Results. A model of nonlinear magnetization oscillations was developed taking into account both a nonlinear frequency shift and a nonlinear attenuation. The resonance curves were experimentally measured at various levels of the microwave power incident on the resonator. It was shown that nonlinear damping limits the nonlinear frequency shift of the magnetization oscillations in a tangentially magnetized ferromagnetic film resonator.Conclusion. The developed model adequately describes behavior of the resonance curves of ferromagnetic film resonators at high microwave power levels. The nonlinear damping leads to broadening of the resonance curves, thereby increasing losses. This effect also increases the reflection coefficient of the microwave signal from the resonator.

We study the conductivity and magnetoresistance of the α‴ phase solid solution of (Cd1−xZnx)3As2 (x = 0.45). Single crystals of (Cd1−xZnx)3As2 are obtained by the modified Bridgman method. The space group and tetragonal lattice parameters of single crystals are found to be I41/amd and a = b = 8.56(5) Å, c = 24.16(6) Å. The temperature dependence of the conductivity and magnetoresistance is studied in the temperature range of 1.6–320 K and in the presence of a transverse magnetic field from 0 to 10 T. Mixed conductivity is analyzed using Hall resistivity data and standard quantitative mobility spectrum analysis. The concentration and mobility of holes are determined at different temperatures. The presence of two types of holes with different mobilities is demonstrated in the temperature range of 1.6–19 K, while with increasing temperature, just one type of charge carrier is observed in the mobility spectrum.

In Mn-doped InSb single crystals an unusual, for nonmagnetic semiconductors, dependence on manganese concentration have been revealed for magnetization, conductivity, magnetoresistance and the Hall effect in the range NMn= (1÷2)×1017cm-3. Noticeable low temperature magnetization increase was observed at NMn≈1×1017cm-3. Strong correlation between magnetization, specific resistivity, Colossal Magnetoresistance (CMR) and the Hall constant as a function of manganese concentration in InSb(Mn) was revealed on the insulating side of the metal-insulator transition at Ncr=2×1017cm-3 and at temperature below 10K. Simultaneously, an onset of ferromagnetic-like response in the magnetic moment measurements of p-InSb(Mn) at NMn≤Ncr= 2×1017 cm-3 was registered. This experimental evidence fits the pattern of triplet excitons switching off from conductivity and demonstrates weak magnetic ordering. The coincidence in transport, magnetotransport properties of p-InSb(Mn) and uniaxially stressed p-InSb(Ge) crystals puts forward the idea that the unusual InSb(Mn) properties could be related to Jahn-Teller distortions caused by Mn.

Abstract We report on the potential application of NIR–to–NIR Nd3+-doped yttrium vanadate nanoparticles with both emission and excitation operating within biological windows as thermal sensors in 123–873 K temperature range. It was demonstrated that thermal sensing could be based on three temperature dependent luminescence parameters: the luminescence intensity ratio, the spectral line position and the line bandwidth. Advantages and limitations of each sensing parameter as well as thermal sensitivity and thermal uncertainty were calculated and discussed. The influence of Nd3+ doping concentration on the sensitivity of luminescent thermometers was also studied.

Abstract Tabby is a pattern of short irregular stripes, usually related to domestic cats. We have produced Tabby patterns on graphene by attaching fluorine atoms running as monoatomic chains in crystallographic directions. Separated by non-fluorinated sp 2 carbon ribbons, sp 3-hybridized carbon atoms bonded to zigzag fluorine chains produce sp 2-sp 3 interfaces and spin-polarized edge states localized on both sides of the chains. We have compared two kinds of fluorinated graphite samples C2F x , with x near to 1 and x substantially below 1. The magnetic susceptibility of C2F x (x

Numerous attempts to develop an efficient anti-cancer agent are focusing on the design of multifunctional objects with synergistic theranostic treatments and minimal side effects. The most prospective treatments which can be used in combination are chemotherapy, photothermal therapy, and photodynamic therapy. To avoid collateral damage, it is important to control local temperature during the treatment procedure. In this work, we demonstrate how free-based and zinc-containing porphyrins can be used as contactless luminescence thermometers. Thermal sensing was provided based on two approaches: ratiometric and lifetime-based techniques. Thermometric performances of suggested temperature sensors including relative sensitivity and temperature resolution were calculated and compared. Keywords: Porphyrins, Thermometry, Luminescence, Lifetime, Sensor

Fragmented multi-layered graphene films were directly synthesized via chemical vapor deposition (CVD) on dielectric substrates with a pre-deposited copper catalyst. We demonstrate that the thickness of the sacrificial copper film, process temperature, and growth time essentially influence the integrity, quality, and disorder of the synthesized graphene. Atomic force microscopy and Kelvin probe force microscopy measurements revealed the presence of nano-agglomerates and charge puddles. The potential gradients measured over the sample surface confirmed that the deposited graphene film possessed a multilayered structure, which was modelled as an ensemble of randomly oriented conductive prolate ellipsoids. THz time domain spectroscopy measurements gave the ac conductivity of the graphene flakes and homogenized graphitic films as being around 1200 S cm -1 and 1000 S cm -1 , respectively. Our approach offers a scalable fabrication of graphene structures composed of graphene flakes, which have effective conductivity sufficient for a wide variety of THz applications., (© 2022 IOP Publishing Ltd.)

Transport characteristics of sodium alginate (SA) membranes cross-linked with CaCl 2 and modified with fullerenol and fullerene derivative with L-arginine for pervaporation dehydration were improved applying various approaches, including the selection of a porous substrate for the creation of a thin selective SA-based layer, and the deposition of nano-sized polyelectrolyte (PEL) layers through the use of a layer-by-layer (Lbl) method. The impacts of commercial porous substrates made of polyacrylonitrile (PAN), regenerated cellulose, and aromatic polysulfone amide were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), standard porosimetry method, and water filtration. The effects of PEL combinations (such as poly(sodium 4-styrene sulfonate) (PSS)/SA, PSS/chitosan, PSS/polyacrylic acid, PSS/poly(allylamine hydrochloride)) and the number of PEL bilayers deposited with the Lbl technique on the properties of the SA and SA/fullerene derivative membranes were studied by SEM, AFM, and contact angle measurements. The best characteristics were exhibited by a cross-linked PAN-supported SA/fullerenol (5%) membrane with five PSS/SA bilayers: permeation flux of 0.68-1.38 kg/(m 2 h), 0.18-1.55 kg/(m 2 h), and 0.50-1.15 kg/(m 2 h), and over 99.7, 99.0, and 89.0 wt.% water in the permeate for the pervaporation dehydration of isopropanol (12-70 wt.% water), ethanol (4-70 wt.% water), and tetrahydrofuran (5.7-70 wt.% water), respectively. It was demonstrated that the mutual application of bulk and surface modifications essentially improved the membrane's characteristics in pervaporation dehydration.

Novel mixed matrix dense and supported membranes based on biopolymer sodium alginate (SA) modified by fullerenol were developed. Two kinds of SA-fullerenol membranes were investigated: untreated and cross-linked by immersing the dry membranes in 1.25 wt % calcium chloride (CaCl 2 ) in water for 10 min. The structural and physicochemical characteristics features of the SA-fullerenol composite were investigated by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic methods, scanning electron (SEM) and atomic force (AFM) microscopies, thermogravimetric analysis (TGA), and swelling experiments. Transport properties were evaluated in pervaporation dehydration of isopropanol in a wide concentration range. It was found that the developed supported cross-linked SA-5/PAN CaCl2 membrane (modified by 5 wt % fullerenol) possessed the best transport properties (the highest permeation fluxes 0.64-2.9 kg/(m 2 h) and separation factors 26-73,326) for the pervaporation separation of the water-isopropanol mixture in the wide concentration range (12-90 wt % water) at 22 °C and is suitable for the promising application in industry.

Peptide dendrimers, due to their biocompatibility and low toxicity, are highly promising candidates as nanocarriers for drugs and genes. The development of this kind of delivery system requires reliable monitoring of their metabolic and biological pathways. In this respect, hydrogen isotope labeling has tremendous importance, being a safe tool for detection of the labeled nanocarriers. In this work, we have synthesized new histidine-rich lysine-based dendrimers (Lys-2His dendrimer) with two linear histidine (His) residues in every inner segment. The presence of His residues has enabled us to perform controlled deuteration of Lys-2His dendrimers. The high deuteration degree (around 70%) does not practically change after redissolving the samples in H 2 O and heating them at 40 °C, which indicates the isotopic label stability.

Segmented poly(urethane-imide)s (PUIs) were synthesized by polyaddition reaction and applied for preparation of membranes. Tolylene-2,4-diisocyanate, pyromellitic dianhydride, and m -phenylenediamine for chain extension were used to form hard aromatic blocks. Polycaprolactone diols with molecular weights equal to 530 and 2000 g mol -1 were chosen as soft segments. The effect of the length of soft segments on the structure, morphology, and transport properties of segmented poly(urethane-imide) membranes were studied using atomic force microscopy, small-angle and wide-angle X-ray scattering, and pervaporation experiments. It was found that a copolymer with a shorter soft segment (530 g mol -1 ) consists of soft domains in a hard matrix, while the introduction of polycaprolactone blocks with higher molecular weight (2000 g mol -1 ) leads to the formation of hard domains in a soft matrix. Additionally, the introduction of hard segments prevents crystallization of polycaprolactone. Transport properties of membranes based on segmented PUIs containing soft segments of different length were tested for pervaporation of a model mixture of propanol/water with 20 wt % H₂O content. It was found that a membrane based on segmented PUIs containing longer soft segments demonstrates higher flux (8.8 kg μm m -2 h -1 ) and selectivity (179) toward water in comparison with results for pure polycaprolactone reported in literature. The membrane based on segmented PUIs with 530 g mol -1 soft segment has a lower flux (5.1 kg μm m -2 h -1 ) and higher selectivity (437).

Chitosan (CS) films containing deep eutectic solvent (DES) based on malonic acid (MA) and choline chloride (ChCl) were successfully prepared by solution casting method by using DES content ranging from 0 to 82 wt%. A strong interaction of CS with the components of DES was demonstrated by analyses of water sorption isotherms, atomic force microscopy and FTIR results. The plasticizing effect of the MA and ChCl mixture on the CS matrix was shown by static bulk mechanical measurements, thermal analysis and quantitative nanomechanical mapping (QNM). Elongation at break increased from 3 to 62% at increase of DES content from 0 to 67 wt%, while further increase of DES content led to the decreasing of maximal elongation. Introduction of DES into CS films led to the appearance of glass transition temperature in the region +2 - -2.3 °C. QNM results indicated homogeneity of the films containing up to 75 wt% of DES., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

We have studied the properties of relatively thick (about 120 nm) magnetic composite films grown by pulsed laser deposition using the eutectic compound (GaSb) 0.59 (MnSb) 0.41 as target for sputtering. For the studied films we have observed ferromagnetism and an anomalous Hall effect above room temperature, confirming the presence of spin-polarized carriers. Electron microscopy, atomic and magnetic force microscopy results suggest that the films under study have a homogenous columnar structure in the bulk while MnSb inclusions accumulate near the surface. This is in good agreement with the high mobility values of charge carriers. Based on our data we conclude that the magnetic and magnetotransport properties of the films at room temperature are defined by the MnSb inclusions.

It is known that structure of the interface between inorganic nanoparticles and polymers significantly influences properties of a polymer⁻inorganic composite. At the same time, amount of experimental researches on the structure and properties of material near the inorganic-polymer interface is low. In this work, we report for the first time the investigation of nanomechanical properties and maps of adhesion of material near the inorganic-polymer interface for the polyheteroarylene nanocomposites based on semi-crystalline poly[4,4'-bis (4″-aminophenoxy)diphenyl]imide 1,3-bis (3',4-dicarboxyphenoxy) benzene, modified by ZrO₂ nanostars. Experiments were conducted using quantitative nanomechanical mapping (QNM) mode of atomic force microscopy (AFM) at the surface areas where holes were formed after falling out of inorganic particles. It was found that adhesion of AFM cantilever to the polymer surface is higher inside the hole than outside. This can be attributed to the presence of polar groups near ZrO₂ nanoparticle. QNM measurements revealed that polymer matrix has increased rigidity in the vicinity of the nanoparticles. Influence of ZrO₂ nanoparticles on the structure and thermal properties of semi-crystalline polyheteroarylene matrix was studied with wide-angle X-ray scattering, scanning electron microscopy, and differential scanning calorimetry., Competing Interests: The authors declare no conflict of interest.

The results of a detailed study of magnetic properties and of the microstructure of SiMn films with a small deviation from stoichiometry are presented. The aim was to reveal the origin of the high temperature ferromagnetic ordering in such compounds. Unlike SiMn single crystals with the Curie temperature ~30 K, considered Si 1-x Mn x compounds with x  =  0.5  +Δx and Δx in the range of 0.01-0.02 demonstrate a ferromagnetic state above room temperature. Such a ferromagnetic state can be explained by the existence of highly defective B20 SiMn nanocrystallites. These defects are Si vacancies, which are suggested to possess magnetic moments. The nanocrystallites interact with each other through paramagnons (magnetic fluctuations) inside a weakly magnetic manganese silicide matrix giving rise to a long range ferromagnetic percolation cluster. The studied structures with a higher value of Δx  ≈  0.05 contained three different magnetic phases: (a)-the low temperature ferromagnetic phase related to SiMn; (b)-the above mentioned high temperature phase with Curie temperature in the range of 200-300 K depending on the growth history and, ((c)-superparamagnetic phase formed by separated noninteracting SiMn nanocrystallites.)

Mixed-matrix membranes based on amorphous and semi-crystalline polyimides with zirconium dioxide (ZrO₂) nanostars were synthesized. Amorphous poly(4,4'-oxydiphenylenepyromellitimide) and semi-crystalline polyimide prepared from 1,4-bis(4-aminophenoxy)benzene and 4,4'-oxydiphthalic anhydride were used. The effect of ZrO₂ nanostars on the structure and morphology of nanocomposite membranes was studied by wide-angle X-ray scattering, scanning electron microscopy, atomic force microscopy, and contact angle measurements. Thermal properties and stability were investigated by thermogravimetric analysis and differential scanning calorimetry. Transport properties of hybrid membranes containing 5 wt % ZrO₂ were tested for pervaporation of a mixture of butanol⁻water with 10 wt % H₂O content. It was found that a significant amount of the ZrO₂ added to the semi-crystalline polyimide is encapsulated inside spherulites. Therefore, the beneficial influence of inorganic filler on the selectivity of mixed-matrix membrane with respect to water was hampered. Mixed-matrix membranes based on amorphous polymer demonstrated the best performance, because water molecules had higher access to inorganic particles.

We have studied copolymer dendrimer structure: carbosilane dendrimers with terminal phenylbenzoate mesogenic groups attached by poly(ethylene) glycol (PEG) spacers. In this system PEG spacers are additional tuning to usual copolymer structure: dendrimer with terminal mesogenic groups. The dendrimer macromolecules were investigated in a dilute chloroform solution by (1)H NMR methods (spectra and relaxations). It was found that the PEG layer in G = 5 generations dendrimer is "frozen" at high temperatures (above 260 K), but it unexpectedly becomes "unfrozen" at temperatures below 250 K (i.e., melting when cooling). The transition between these two states occurs within a small temperature range (~10 K). Such a behavior is not observed for smaller dendrimer generations (G = 1 and 3). This effect is likely related to the low critical solution temperature (LCST) of PEG and is caused by dendrimer conformations, in which the PEG group concentration in the layer increases with growing G. We suppose that the unusual behavior of PEG fragments in dendrimers will be interesting for practical applications such as nanocontainers or nanoreactors.

The developed theory of the orientational mobility of individual segments of a perfectly branched dendrimer is used to calculate the relaxation spectrum of a dendrimer. Frequency dependences of NMR relaxation 1/T(1) and of the nuclear Overhauser effect have been theoretically calculated from the Brownian dynamics simulation data. The dendrimer segmental orientational mobility is governed by three main relaxation processes: (i) the rotation of the dendrimer as a whole, (ii) the rotation of the dendrimer's branch originated from a given segment, and (iii) the local reorientation of the segment. The internal orientational mobility of an individual dendrimer segment depends only on the topological distance between this segment and the terminal shell of the dendrimer. Characteristic relaxation times of all processes and their contributions to the segmental mobility have been calculated. The influence of the number of generations and the number of the generation shell on the relaxation times has been studied. The correlation between the characteristic times and the calculated relaxation spectrum of the dendrimer has been established.