New Publications

https://doi.org/10.1134/S1061933X23601075

Layered two-dimensional materials, whose properties dramatically differ from their bulk precursors, are of great theoretical and applied importance. Recently, a layered 2D material, an analog of a natural mineral, valleriite, in which quasi-monoatomic Cu−Fe−S sheets alternate with brucite-like ones, has been prepared using a simple hydrothermal synthesis procedure. The features of the electronic structure of these materials make it possible to propose them as new materials for a wide field of applications such as (electro)photocatalysis, high-capacity batteries, etc. In this work, nanocomposite materials have been prepared via immobilization of gold nanoparticles (AuNPs) from citrate hydrosols on the surface of the synthesized valleriites having different compositions of hydroxide layers, which control the surface charge density. According to X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersive X-ray microanalysis (EDX), and selected area electron diffraction (SAED) data, AuNPs are immobilized on valleriite nanoflakes, which have lateral sizes of 150–200 nm and thicknesses of several tens of nanometers, as isolated metal nanoparticles with an average diameter of 11 nm. A small amount of aggregates indicates a high affinity of AuNPs for the valleriite surface. The amounts of immobilized gold are the same on all studied valleriites (~0.2%). This finding may be related to the simultaneous sorption of free citrate ions from the AuNP hydrosols, with these ions, according to zeta potential measurements, charging the surfaces of all studied valleriite samples to nearly the same negative value of –40 mV. According to the XPS data, the AuNPs immobilization markedly decreases the magnesium and oxygen contents on the surfaces of the synthesized valleriites due to the partial degradation/dissolution of the brucite layer. In addition, the amount of Fe³⁺ ions bound to OH groups decreases with a simultaneous increase in the fraction of Fe³⁺–O species. The TEM data have confirmed the preservation of the layered structure of valleriites after the immobilization of AuNPs.

https://doi.org/10.1016/j.optmat.2024.115232

The modulation and spectral characteristics of self-organized ensembles of nematic domains with the disclination lines non-aligned and aligned in a magnetic field have been studied using an electric field. The obtained experimental voltage dependences of the light transmission agree well with the dependences calculated using the model considerations. These dependences have been compared with the electro-optical characteristics of a homogeneous planar nematic layer. The amplitude component of the optical transmission determined by light scattering and the oscillating component caused by the phase modulation have been examined. The effect of the spectral dispersion of transmission on the electro-optical characteristics of domain ensembles has been evaluated.

https://doi.org/10.1016/j.physc.2024.1354486

Porosity affects the properties of high-T_c superconductors and can improve their performance by enhancing oxygenation, cryocooling, etc. Among other factors, the presence of pores plays a significant role in the process of magnetic flux trapping. Relationships with the porosity manifest in the irreversibility field, the full penetration field, and the remnant magnetization of the samples. To account for the effect of porosity on the trapped magnetic flux into type-II superconductors, a simple toy model is suggested. Generally, as the porosity increases, the trapped flux and related parameters tend to diminish. However, in the case of microscopic samples, porosity can enhance magnetic flux trapping.

 https://doi.org/10.1002/adom.202303235

Far-red (FR) region (beyond 700 nm) lighting sources possess special potential for plant lighting. However, it remains a challenge to obtain high-performance Cr³⁺-doped FR phosphors. This study developed a FR phosphor, Ca_1.8Mg_1.2Al₂Ge₃O₁₂:Cr³⁺ (CMAGG: Cr³⁺), using the cation substitution strategy. Under 438 nm blue light excitation, the phosphors display FR emission centered at 720 nm with a full width at half maximum (FWHM) of 91 nm. Benefit from the favorable match with the FR phytochrome (P_fr), the phosphor is combined with InGaN blue light chips to create a FR phosphor-converted light-emitting diode (pc-LED), which is used in Italian lettuce growth experiments and it results shown in a 15% increase in fresh weight and a 6.5% increase in dry weight. Notably, supplemental FR light modulated its growth morphology. The results of this study will be useful for further research on novel Cr³⁺-doped FR phosphors to meet the precise spectral requirements for plant growth.

https://doi.org/10.1021/acs.inorgchem.3c04140

Optical thermometry has gained significant attention due to its remarkable sensitivity and noninvasive, rapid response to temperature changes. However, achieving both high absolute and relative temperature sensitivity in two-dimensional perovskites presents a substantial challenge. Here, we propose a novel approach to address this issue by designing and synthesizing a new narrow-band blue light-emitting two-dimensional perovskite named (C₈H₁₂NO₂)₂PbBr₄ using a straightforward solution-based method. Under excitation of near-ultraviolet light, (C₈H₁₂NO₂)₂PbBr₄ shows an ultranarrow emission band with the full width at half-maximum (FWHM) of only 19 nm. Furthermore, its luminescence property can be efficiently tuned by incorporating energy transfer from host excitons to Mn²⁺. This energy transfer leads to dual emission, encompassing both blue and orange emissions, with an impressive energy transfer efficiency of 38.3%. Additionally, we investigated the temperature-dependent fluorescence intensity ratio between blue emission of (C₈H₁₂NO₂)₂PbBr₄ and orange emission of Mn²⁺. Remarkably, (C₈H₁₂NO₂)₂PbBr₄:Mn²⁺ exhibited maximum absolute sensitivity and relative sensitivity values of 0.055 K^–1 and 3.207% K^–1, respectively, within the temperature range of 80–360 K. This work highlights the potential of (C₈H₁₂NO₂)₂PbBr₄:Mn²⁺ as a promising candidate for optical thermometry sensor application. Moreover, our findings provide valuable insights into the design of narrow-band blue light-emitting perovskites, enabling the achievement of single-component dual emission in optical thermometry sensors.

DOI: 10.1109/TGRS.2023.3340693

This article is the second in a series evaluating the effect of dielectric relaxation processes on the relatively effective complex dielectric permittivity (RCP) of soils. Part II is based on the results of experimental measurements in the frequency range 10 kHz to 8–20 GHz. The broadband dielectric spectrum model includes the high-frequency part as a model of the dielectric mixture and the relaxation part as the sum of three relaxation processes modeled by the Debye and Cole–Cole formulas. For modeling the high-frequency part of the spectrum, the Dobson and Mironov models were considered as possible options. As stated in Part I, the influence of relaxation processes on the imaginary part of the RCP extends up to frequencies of units of gigahertz. The increase in the imaginary part in these models was compensated by unrealistically high values of the specific electrical conductivity of free and bound water. We examined the correspondence of these models to experimental data at frequencies above 2–5 GHz, assuming that the conductivity of bound and free water is zero. The parameters of relaxation processes were found while solving the least-square optimization problem using the technique for determining the continuous distribution of relaxation times (DRTs). Found process parameters depend on the content of clay, organic carbon, and moisture of the samples. The more clay is in the soil, the greater the strength of these processes is. The influence of organic carbon with the conditions being equal consists in the reduction of the real and imaginary parts of RCP.

https://doi.org/10.3390/molecules29040848

Aptamers are currently being investigated for their potential to improve virotherapy. They offer several advantages, including the ability to prevent the aggregation of viral particles, enhance target specificity, and protect against the neutralizing effects of antibodies. The purpose of this study was to comprehensively investigate an aptamer capable of enhancing virotherapy. This involved characterizing the previously selected aptamer for vaccinia virus (VACV), evaluating the aggregation and molecular interaction of the optimized aptamers with the recombinant oncolytic virus VV-GMCSF-Lact, and estimating their immunoshielding properties in the presence of human blood serum. We chose one optimized aptamer, NV14t_56, with the highest affinity to the virus from the pool of several truncated aptamers and built its 3D model. The NV14t_56 remained stable in human blood serum for 1 h and bound to VV-GMCSF-Lact in the micromolar range (Kd ≈ 0.35 μM). Based on dynamic light scattering data, it has been demonstrated that aptamers surround viral particles and inhibit aggregate formation. In the presence of serum, the hydrodynamic diameter (by intensity) of the aptamer–virus complex did not change. Microscale thermophoresis (MST) experiments showed that NV14t_56 binds with virus (EC50 = 1.487 × 10⁹ PFU/mL). The analysis of the amplitudes of MST curves reveals that the components of the serum bind to the aptamer–virus complex without disrupting it. In vitro experiments demonstrated the efficacy of VV-GMCSF-Lact in conjunction with the aptamer when exposed to human blood serum in the absence of neutralizing antibodies (Nabs). Thus, NV14t_56 has the ability to inhibit virus aggregation, allowing VV-GMCSF-Lact to maintain its effectiveness throughout the storage period and subsequent use. When employing aptamers as protective agents for oncolytic viruses, the presence of neutralizing antibodies should be taken into account.

Most known mixed manganites containing rare-earth elements demonstrate a pronounced charge ordering (CO) state below room temperature. The behavior of the magnetic susceptibility and electronic magnetic resonance of polycrystalline Pr_1−xSr_xMnO₃/YSZ (x = 0.2 and x = 0.4) films without a pronounced texture indicates the formation of the CO phase in the samples at temperatures close to and above room temperature. Moreover, this phase manifests itself with a typical sign of martensitic transformation. The same phenomenon has been traced for textured polycrystalline La_0.7Sr_0.3MnO₃/YSZ films. Electron microscope data indicate the presence of internal strain within the films, which is probably responsible for the formation of the CO phase. It is assumed that the reasons for the appearance of such strain include the crystallite size and the boundary between them. The results obtained provide the basis for the development of new research and technological tasks for the generation of the high-temperature CO state in various polycrystalline rare-earth manganites, since this state contributes to the manifestation of interesting magnetocaloric, magnetoelectric and multiferroic properties. In addition, recent data has opened up new opportunities for studying the strain-induced phenomena in such materials.

https://doi.org/10.1016/j.cjph.2023.11.030

Vortex relaxation has been studied in a microsized HTS with various distributions of artificial pinning in the form of submicro-holes. It has been shown that, in some cases, for a superconductor with dimensions up to several micrometers, the time dependences of the trapped magnetic field do not correspond with the collective creep model. The dependences of the trapped-field relaxation rate and vortex activation energy on the magnetizing field (up to 0.5 T) and temperature (up to 50 K) have been obtained. It has been shown that the presence of submicro-holes slightly increases the relaxation rate, mainly due to the decrease in the number of random nanosized pinning centers.

https://doi.org/10.1016/j.chemphys.2024.112257

We present first study of magnetic circular dichroism (MCD) spectra of Ho³⁺ ion in C_4v local symmetry, which it has in fluorite Na_0.4Ho_0.6F_2.2. Optical absorption and MCD spectra were studied in this single crystal in the region of ⁵I₈→ ⁵F₃, ⁵F₂, ³K₈ and ⁵G₅ transitions in the temperature range 3.6–––90 K. It was revealed, that number of transitions observed in the MCD and absorption spectra coincides with the number of transitions only from the doublet E state to singlet excited states. The E-E type transitions are not active in MCD, but they are not observed in the absorption spectra either. Paramagnetic magneto-optical activities (MOA) of the absorption bands and their temperature dependences were measured and interpreted with the help of the theory based on the nature of f-f transitions allowance. The MCD spectra were also analyzed in approximation of the �,±�� wave functions of the free atom. It was shown in particular, that the lowest initial state of the transitions observed at T > 10 K had M_J = 7, but this is not the lowest state of the holmium ion in the crystal. A little lower there is a quasi-doublet with M_J = 8 and, accordingly, with a higher magneto-optical activity of transitions from it. However, the intensity of transitions from this state is low.

https://doi.org/10.1080/01431161.2024.2313993

This article investigated the possibility of remotely sensing the soil moisture profile in thawed soil from multi-angular dual-polarized brightness temperature (TB) observations at P-band frequencies of 750 MHz and 409 MHz using a modified Burke model. Moreover, it was found that an excellent agreement (coefficient of determination R² = 0.999 and root-mean-square error (RMSE) no more than RMSE = 0.6 K) could be achieved between the Njoku coherent brightness temperature model and the modified Burke model by introducing a reflectivity from the air-soil interface that takes into account the phases of the multiple re-reflected waves in the underlying layers. Based on the modified Burke model, the depths from which apparent moisture and temperature could be retrieved in a dielectrically-inhomogeneous, non-isothermal soil were investigated, being approximately ten times less than the depth for which apparent soil temperature could be retrieved. In general, the thickness of the emitting layer depends on the TB look angle and polarization, along with the moisture and temperature profiles of the soil. It was also shown that due to the effect of the Brewster angle, the H-polarization of TB was twice as sensitive (4 K/1%) to changes in volumetric soil moisture than V-polarization (1.9 K/1%). Based on multi-angular (10°-50°) observations of TB at H- and V-polarizations, a method of moisture profile retrieval in the top 5–15 cm soil (depending on surface moisture) was proposed using an exponential fitting function, the parameters of which are found in the course of solving the inverse problem. A decrease in the sensing frequency from 750 MHz to 409 MHz makes it possible to increase the accuracy of soil moisture profiles retrieval by a factor of two, being from RMSE = 1.6% (R² = 0.946) to RMSE = 0.85% (R² = 0.982) in the top 15 cm layer of soil. The conducted investigation shows the promise of using P-band observations of TB for soil moisture profile retrieval.

https://doi.org/10.1016/j.diamond.2024.110844

In this study, particles of synthetic undoped diamond (D_N) obtained via the high pressure – high temperature method were coated with a nickel shell using metallic nickel plasma in a two-jet plasma generator with gas vortex and magnetic flux stabilization. Through the use of scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, we observed the formation of a nickel diamond composite with a core-shell structure, where D_N serves as the core and Ni nanoclusters form the shell (D_N@Ni). The results of voltammetric analysis indicated that D_N@Ni, when deposited on a graphite electrode, exhibited significant electrocatalytic activity in the oxidation of methanol and paracetamol in an alkaline electrolyte.

https://doi.org/10.48550/arXiv.2402.00547

In this work, the effect of uniaxial pressure along the c axis on the electronic structure of the HTSC cuprate La2-xSrxCuO4 is investigated at the doping levels x = 0.1, 0.15, 0.25. The GTB method within the five-band p-d model framework is used to describe the electron system. The uniaxial compression leads to a significant reconstruction of the electronic structure and a change in the character of low-energy quasiparticle excitations: a large contribution of a1g symmetry orbitals appears at the top of the valence band. The crossover between the local Zhang-Rice singlet and the Emery-Reiter triplet was found at the pressure Pc = 15.1 GPa. The characteristic changes in the electronic structure under pressure occur abruptly as a result of the crossover. In particular, the top of the valence band displaces to the region around the k-point (pi,0), the Fermi contour transforms to the four pockets around (0,0),(2pi,0),(0,2pi),(2pi,2pi) and the one contour around (pi,pi).

https://doi.org/10.1134/S1028335823120030

The monolithic design of a compact bandpass filter X-band is made on the technology of multilayered printed circuit boards. Quarter-wave stripline resonators of the filter have two conductors divided by a layer of prepreg having low parameters that bond together the design. This eliminates the influence of the prepreg on the characteristics of the devices, ensuring good repeatability of filters in mass production. To increase the high-frequency stopband of the filter, one of the conductors of each resonator is cut in half by a transverse slit. The constructive sizes of the device were obtained by parametric synthesis using the electrodynamic analysis of its 3D model. The experimental data of the five-order filter are in good agreement with the electromagnetic simulation of filter of the 3D model. The experimental device has a central frequency of the passband of 10 GHz and a fractional bandwidth of 5.7%, and its dimensions and weight are 18.0 × 5.4 × 2.1 mm³ and 0.5 g. The important advantage of the developed design is the possibility of its installation on the board using the surface mounting method.

https://doi.org/10.3389/fphy.2024.1322162

In the context of the 21st century and the fourth industrial revolution, the substantial proliferation of data has established it as a valuable resource, fostering enhanced computational capabilities across scientific disciplines, including physics. The integration of Machine Learning stands as a prominent solution to unravel the intricacies inherent to scientific data. While diverse machine learning algorithms find utility in various branches of physics, there exists a need for a systematic framework for the application of Machine Learning to the field. This review offers a comprehensive exploration of the fundamental principles and algorithms of Machine Learning, with a focus on their implementation within distinct domains of physics. The review delves into the contemporary trends of Machine Learning application in condensed matter physics, biophysics, astrophysics, material science, and addresses emerging challenges. The potential for Machine Learning to revolutionize the comprehension of intricate physical phenomena is underscored. Nevertheless, persisting challenges in the form of more efficient and precise algorithm development are acknowledged within this review.

https://doi.org/10.1063/5.0183334

Golden nanoparticle dimers connected by conjugated molecular linkers 1,2-bis(2-pyridyl)ethylene are produced. The formation of stable dimers with 22 nm diameter nanoparticles is confirmed by transmission electron microphotography. The possibility of charge transfer through the linkers between the particles in the dimers is shown by the density functional theory calculations. In addition to localized plasmon resonance of solitary nanoparticles with a wavelength of 530 nm, the optical spectra exhibit a new intense absorption peak in the near-infrared range with a wavelength of ∼780 nm. The emergent absorption peak is attributed to the charge-transfer plasmon (CTP) mode; the spectra simulated within the CTP developed model agree with the experimental ones. This resonant absorption may be of interest to biomedical applications due to its position in the so-called transmission window of biological tissues. The in vitro heating of CTP dimer solution by a laser diode with a wavelength of 792 nm proved the efficiency of CTP dimers for achieving a temperature increase of ΔT = 6 °C, which is sufficient for hyperthermia treatment of malignant tumors. This indicates the possibility of using hyperthermia to treat malignant tumors using the material we synthesized.

https://doi.org/10.1016/j.jmmm.2024.171906

Manifestations of quantum effects in the macroscopic properties of frustrated magnets keep attracting considerable interest. We have formulated and studied a simple model of a three-sublattice mixed-spin (�=1,1/2,1/2) ��(3)-ferrimagnet on triangular lattice in which the strong quantum fluctuations are developed due to combined effect of frustrated exchange bonds, reduced dimensionality and a single-ion easy-plane anisotropy in the spin-1 sublattice. To account correctly for the ��(3) algebra, the Hubbard operators representation of generators is used. Dependencies of the magnetic moments � and �� (for spin-1/2 and spin-1 sublattices respectively), the total magnetic moment �, as well as the quadrupole moment, on the anisotropy parameter � are calculated at zero temperature and different ratios �/� of exchange integrals from different sublattices. It is established that for �/�≪1 the critical value ��, at which the system enters the quadrupole antiferromagnetic phase, can be much smaller than both � and �. Besides, with an increase in � from zero to �� the total moment � can change its direction several times via taking zero value. Classification of four branches of the spin-wave excitation spectrum of the ��(3)-ferrimagnet is carried out and modification of the spectrum with change in the single-ion anisotropy is analyzed.

https://doi.org/10.1016/j.jssc.2024.124640

The NdF₃–Nd₂S₃ system attracts attention of researchers due to the possibility of using LnSF compounds (Ln = rare earth element) as possible new p- and n-type materials. The samples of this system were synthesized from NdF₃ and Nd₂S₃. The NdSF compound belongs to the PbFCl structural type, P4/nmm space group, unit cell parameters: a = 3.9331(20) Å, c = 6.9081(38) Å. The experimentally determined direct and indirect NdSF bandgaps are equal to 2.68 eV and 2.24 eV. The electronic band structure was calculated via DFT simulation. The NdSF compound melts congruently at T = 1385 ± 10°С, ΔН_m = 40.5 ± 10 kJ/mol, ΔS = 24.4 ± 10 J/mol. The NdSF microhardness is 455 ± 10 HV. Five phase transformations in the NdF₃–Nd₂S₃ system were recorded by DSC; their balance equations were derived. The liquidus of the system calculated from the Redlich–Kister equation is fully consistent with the DSC data.

https://doi.org/10.1002/adom.202303235

Far-red (FR) region (beyond 700 nm) lighting sources possess special potential for plant lighting. However, it remains a challenge to obtain high-performance Cr³⁺-doped FR phosphors. This study developed a FR phosphor, Ca_1.8Mg_1.2Al₂Ge₃O₁₂:Cr³⁺ (CMAGG: Cr³⁺), using the cation substitution strategy. Under 438 nm blue light excitation, the phosphors display FR emission centered at 720 nm with a full width at half maximum (FWHM) of 91 nm. Benefit from the favorable match with the FR phytochrome (P_fr), the phosphor is combined with InGaN blue light chips to create a FR phosphor-converted light-emitting diode (pc-LED), which is used in Italian lettuce growth experiments and it results shown in a 15% increase in fresh weight and a 6.5% increase in dry weight. Notably, supplemental FR light modulated its growth morphology. The results of this study will be useful for further research on novel Cr³⁺-doped FR phosphors to meet the precise spectral requirements for plant growth.

https://doi.org/10.3390/molecules29040848

Aptamers are currently being investigated for their potential to improve virotherapy. They offer several advantages, including the ability to prevent the aggregation of viral particles, enhance target specificity, and protect against the neutralizing effects of antibodies. The purpose of this study was to comprehensively investigate an aptamer capable of enhancing virotherapy. This involved characterizing the previously selected aptamer for vaccinia virus (VACV), evaluating the aggregation and molecular interaction of the optimized aptamers with the recombinant oncolytic virus VV-GMCSF-Lact, and estimating their immunoshielding properties in the presence of human blood serum. We chose one optimized aptamer, NV14t_56, with the highest affinity to the virus from the pool of several truncated aptamers and built its 3D model. The NV14t_56 remained stable in human blood serum for 1 h and bound to VV-GMCSF-Lact in the micromolar range (Kd ≈ 0.35 μM). Based on dynamic light scattering data, it has been demonstrated that aptamers surround viral particles and inhibit aggregate formation. In the presence of serum, the hydrodynamic diameter (by intensity) of the aptamer–virus complex did not change. Microscale thermophoresis (MST) experiments showed that NV14t_56 binds with virus (EC50 = 1.487 × 10⁹ PFU/mL). The analysis of the amplitudes of MST curves reveals that the components of the serum bind to the aptamer–virus complex without disrupting it. In vitro experiments demonstrated the efficacy of VV-GMCSF-Lact in conjunction with the aptamer when exposed to human blood serum in the absence of neutralizing antibodies (Nabs). Thus, NV14t_56 has the ability to inhibit virus aggregation, allowing VV-GMCSF-Lact to maintain its effectiveness throughout the storage period and subsequent use. When employing aptamers as protective agents for oncolytic viruses, the presence of neutralizing antibodies should be taken into account.

https://doi.org/10.46690/capi.2024.03.02

Experimental oil displacement as a result of spontaneous imbibition of silica nanosols has been carried out using two types of sandstone as the reservoir rock. The permeability of the cores ranged from 0.34 to 333 mD, while the porosity was 11% and 22%, respectively. During the research, the influence of the concentration and nanoparticle size, as well as the permeability of the rock, on the process of spontaneous imbibition, was studied. Silica nanosols were considered as an object of study. The nanoparticle size ranged from 10 to 35 nm. The mass concentration of nanoparticles varied from 0.01% to 0.25%. It was found that the use of silica nanosols significantly increases the rate of the spontaneous imbibition process. It was established that a silica nanosol with a nanoparticle size of 10 nm and a concentration of 0.25% allows to displace more than six times oil compared to the reservoir water model in the same time. As a result, it was shown that the oil displacement efficiency and the efficiency of spontaneous imbibition increase along with an increase in the nanoparticle concentration and a decrease in the nanoparticle size.

• DOI: 10.1016/j.ijbiomac.2024.130252

Properties of degradable polyhydroxyalkanoates with different monomer compositions

https://doi.org/10.1016/j.commatsci.2024.112859

The magnetic and electronic properties of transition metal borates Me₃B₂O₆ (Me = Mn, Fe, Co, Ni) with kotoite structure have been investigated at ambient and high pressures via a combination of representation analysis and density functional theory (DFT + U) calculations. Several magnetic configurations corresponding to the different irreducible representations have been considered. The total-energy calculations reveal that the magnetic ground state of Me₃B₂O₆ kotoites is composition-dependent. The lowest energy magnetic phase of manganese and nickel kotoites is characterized by the antiferromagnetic ordering of the transition metal magnetic moments along the c- axis and along the b-axis for cobalt and iron kotoites. The magnetic cell of Ni₃B₂O₆ kotoite corresponds to k = (1/2, 0, 1/2) vector and four time larger than the unit cell. The calculated exchange constants indicate the competition between ferromagnetic and antiferromagnetic interactions. At a critical pressure, Me ions undergo a high-spin to low-spin state crossover. This magnetic moments collapse is analyzed in terms of change in electronic structure under pressure.

DOI 10.1088/1361-648X/ad258c

Using local ferromagnetic resonance spectroscopy, we have studied the magnetic properties near edges of thin tangentially magnetized permalloy films, in which a well-defined uniaxial magnetic anisotropy was induced perpendicular to one of the edges. In the experiment, two samples with thicknesses of 90 and 300 nm and with slightly different compositions were examined. To explain the magnetization dynamics near edges, we propose a simple yet effective model of a film in the form of a rectangular prism, which yields the modified Kittel formula for the resonance frequency. In this formula, the locally averaged distance-dependent demagnetizing field that emerges near the edges is included as an additional uniaxial anisotropy term. The measurements reveal that at a certain distance from the edge, the resulting (apparent) anisotropy, determined from the angular dependencies of the resonance field, almost vanishes. Moreover, its easy axis reorients to become parallel to the edge. The model predictions agree well with these results, proving that the main resonance mode behavior near the film edges can be accurately described by introducing additional effective uniaxial anisotropy, provided the measuring area is relatively large. However, for the thick (300 nm) sample, additional precession modes are also observed. These modes distort the angular dependence of the main mode, thus demonstrating the limitations of the model.

DOI: https://doi.org/10.1039/D4DT00038B

The threshold structural transformation of the DUT-4 metal–organic framework (MOF) from an ordered to distorted phase during exposure to ambient conditions has been revealed. The in situ X-ray diffraction analysis, in situ Raman and FTIR spectroscopy, scanning electron microscopy and synchronous thermal analysis have been used for investigation. The reversible effect of exposure time and humidity on such a phase transition has been confirmed. We also demonstrated that the observed phase transition correlated well with changes in the optical and electronic properties of DUT-4, paving the way to a new family of MOF-based phase change materials for optoelectronic applications.

https://doi.org/10.1021/acs.inorgchem.3c04140

Optical thermometry has gained significant attention due to its remarkable sensitivity and noninvasive, rapid response to temperature changes. However, achieving both high absolute and relative temperature sensitivity in two-dimensional perovskites presents a substantial challenge. Here, we propose a novel approach to address this issue by designing and synthesizing a new narrow-band blue light-emitting two-dimensional perovskite named (C₈H₁₂NO₂)₂PbBr₄ using a straightforward solution-based method. Under excitation of near-ultraviolet light, (C₈H₁₂NO₂)₂PbBr₄ shows an ultranarrow emission band with the full width at half-maximum (FWHM) of only 19 nm. Furthermore, its luminescence property can be efficiently tuned by incorporating energy transfer from host excitons to Mn²⁺. This energy transfer leads to dual emission, encompassing both blue and orange emissions, with an impressive energy transfer efficiency of 38.3%. Additionally, we investigated the temperature-dependent fluorescence intensity ratio between blue emission of (C₈H₁₂NO₂)₂PbBr₄ and orange emission of Mn²⁺. Remarkably, (C₈H₁₂NO₂)₂PbBr₄:Mn²⁺ exhibited maximum absolute sensitivity and relative sensitivity values of 0.055 K^–1 and 3.207% K^–1, respectively, within the temperature range of 80–360 K. This work highlights the potential of (C₈H₁₂NO₂)₂PbBr₄:Mn²⁺ as a promising candidate for optical thermometry sensor application. Moreover, our findings provide valuable insights into the design of narrow-band blue light-emitting perovskites, enabling the achievement of single-component dual emission in optical thermometry sensors.

https://doi.org/10.1021/acs.cgd.3c01154

nsights into the mechanical properties of DUT-8(Ni) MOF crystals capable of structural phase transitions are presented. The open and closed pore phases of DUT-8(Ni) are drastically different in their mechanical behavior. For the open-pore phase, a huge anisotropy of compressibility and shear modulus is observed, caused by the presence of two orthogonal motives formed by aromatic linkers bound with Ni atoms via Ni–O bonds. The possibility of easy shifting of linkers with breaking and formation of new Ni–O and Ni–N bonds at the application of shear stress, which is at the same time more stable at uniaxial stress, is shown on the basis of the stiffness tensor analysis. This fact assumes the flexibility of the open-pore phase crystals and their ability for structural transformation. The less prominent anisotropy of elastic moduli and the increased values of these moduli for the closed-pore phase crystals indicate the predominantly hardness and absence of flexibility of this phase.

DOI https://doi.org/10.1039/D3TC02823B

Phytochrome P_FR plays a key role in plant photomorphogenesis, and its perception of far-red light is essential, but how to obtain an efficient far-red phosphor to achieve accurate light filling remains a huge challenge. In this study, Gd_1−y−zAl_3−x(BO₃)₄:xCr³⁺,yLu³⁺,zSm³⁺ (GAB:xCr³⁺,yLu³⁺,zSm³⁺) series phosphors were synthesized by a high-temperature solid-state method. By doping Lu³⁺, the emission intensity of Cr³⁺ could increase as high as 20%. With the introduction of Sm³⁺, the emission intensity of Cr³⁺ was further increased by 29%. Particularly, the emission spectra can be tuned by varying the concentration ratio of Sm³⁺ and Cr³⁺, more suitable for the absorption spectrum of P_FR. Moreover, the internal quantum yield and external quantum yield of GL_0.1AB:0.03Cr³⁺ and GL_0.1AB:0.03Cr³⁺,0.003Sm³⁺ were 83.1% and 24.7% and 78.1% and 26.3%, respectively. There were high anti-thermal quenching properties in the prepared phosphors at 423 K, with 107.6% (GAB:0.03Cr³⁺), 103.1% (GL_0.1AB:0.03Cr³⁺), and 102.7% (GL_0.1AB:0.003Sm³⁺,0.03Cr³⁺). Finally, the phosphors were made into pc-LED devices, which can realize the adjustable orange-red and far-red luminescence and meet the needs of plant lighting applications. In the light-regulated plant growth experiment, compared with the control group, far-red light promoted root growth in plants, confirming the application potential of the prepared phosphors in indoor plant cultivation.

https://doi.org/10.1134/S0021364024600046

We consider the effect of the nematic order on the formation of the superconducting state in iron pnictides and chalcogenides. Nematic order with the B_2g symmetry is modelled as the d-type Pomeranchuk instability and treated within the mean-field approach. Calculated nematic order parameter depends on the nematic interaction coefficient and abruptly changes with the coefficient’s increase. The superconducting solution is obtained within the spin-fluctuation pairing theory. We show that the leading solution in the nematic phase has a s_π± structure. From the critical temperature T_c estimations, we conclude that the nematic superconducting state of the s_π± type is more favorable than the usual s_± and ��2−�2 type states appearing in the absence of the nematicity

Zhidkie Kristally i Ikh Prakticheskoe Ispol'zovanie, 23(4), pp. 49-57.