Compositional engineering of the optical properties of hybrid organic–inorganic lead halide perovskites is crucial for the realization of efficient solar cells and light-emitting devices. We study ...the effect of band gap fluctuations on coherent exciton dynamics in a mixed FA0.9Cs0.1PbI2.8Br0.2 perovskite crystal by using photon echo spectroscopy. We reveal a narrow homogeneous exciton line width of 16 μeV at a temperature of 1.5 K. The corresponding exciton coherence time T 2 = 83 ps is exceptionally long due to the localization of excitons at the scale of tens to hundreds of nanometers. From spectral and temperature dependences of the two- and three-pulse photon echo decay, we conclude that for low-energy excitons pure decoherence associated with elastic scattering on phonons is comparable with the exciton lifetime, while for excitons with higher energies, inelastic scattering to lower energy states via phonon emission dominates.
The structure and the magnetic anisotropy of the films obtained by simultaneous deposition of iron and silicon on n-Si(111) 7×7 at 130°C are investigated. It is found the uniaxial magnetic anisotropy ...field for the Fe1−xSix films with x=0.25 (Fe3Si stoichiometric ratio) deposited on Si(111) 7×7 depends on both the surface miscut angle and the oblique sputtering direction and changes from 0.82Oe up to 117.26Oe.
•The structure and the magnetic anisotropy of the Fe-Si films are investigated.•Magnetic anisotropy depends on both the surface miscut and the oblique sputtering.•Uniaxial magnetic anisotropy field for Fe-Si films changes from 0.82 to 117.26Oe.
The growth of α-FeSi
2
nanocrystal ensembles on gold-activated and gold-free Si(001) surfaces at different Si/Fe flux ratios
via
molecular beam epitaxy is reported. The study reveals that the ...utilisation of gold as a catalyst regulates the preferable orientation relationship (OR) of the nanocrystals to silicon and their morphology at a given Si/Fe flux ratio. α-FeSi
2
free-standing crystals with continuously tuned sizes from 30 nm up to several micrometres can be grown with an α(001)//Si(001) basic OR under gold-assisted conditions and an α(111)//Si(001) OR under gold-free growth conditions on a Si(001) surface. The preferred morphology of nanocrystals with a particular OR can be altered through changes to the Si/Fe flux ratio. Herein, the microstructure and basic OR between the silicide nanocrystals and the silicon substrate, and the formation of nanocrystal facets were analysed in detail with the help of microscopic techniques and simulation methods based on the analysis of near coincidence site (NCS) distributions at silicide/silicon interfaces. On the basis of the simulations used, we managed to reveal the nature of the interfaces observed for the main types of α-FeSi
2
nanocrystals grown. Three types of interfaces typical for nanoplates with an α(001)//Si(001) basic OR, which are (i) stepped, (ii) stressed, and (iii) flat, are explained based on the tendency for the NCS density to increase at the interface. The results presented reveal the potential for the bottom-up fabrication of α-FeSi
2
nanocrystals with tuned physical properties as potentially important contact materials and as building blocks for future nanoelectronic devices.
An approach for tuning the preferable orientation relationships and shapes of free-standing α-FeSi
2
nanocrystals was demonstrated on a Si(001) surface.
We study operation of a superconducting quantum interference devices (SQUIDs) based on a new bilayer material. They can be used for the ultra-sensitive detection of magnetic momentum at temperatures ...down to milliKelvin range. Typically, thermal origin hysteresis of the symmetric SQUID current-voltage curves limits operating temperatures to T>0.6Tc. We used a new bilayer material for SQUID fabrication, namely proximity-coupled superconductor/normal-metal (S/N) bilayers (aluminum 25 nm/platinum 5 nm). Because of the 5 nm Pt-layer, Al/Pt devices show nonhysteretic behavior in a broad temperature range from 20 mK to 0.8 K. Furthermore, the Al/Pt bilayer devices demonstrate an order of magnitude lower critical current compared to the Al devices, which decreases the screening parameter (βL) and improves the modulation depth of the critical current by magnetic flux. Operation at lower temperatures reduces thermal noise and increases the SQUID magnetic field resolution. Moreover, we expect strong decrease of two-level fluctuators on the surface of aluminum due to Pt-layer oxidation protection and hence significant reduction of the 1/f noise. Optimized geometry of Al/Pt symmetric SQUIDs is promising for the detection of single-electron spin flip.
Dysferlinopathy treatment is an active area of investigation. Gene therapy is one potential approach. We studied muscle regeneration and inflammatory response after injection of an AAV-9 with a ...codon-optimized DYSF gene. A dual-vector system AAV.DYSF.OVERLAP with overlapping DYSF cDNA sequences was generated. Two AAV vectors were separately assembled by a standard triple-transfection protocol from plasmids carrying parts of the DYSF gene. Artificial myoblasts from dysferlin-deficient fibroblasts were obtained by MyoD overexpression. RT-PCR and Western blot were used for RNA and protein detection in vitro. A dysferlinopathy murine model (Bla/J) was used for in vivo studies. Histological assay, morphometry, and IHC were used for the muscle tissue analysis. Dysferlin was detected in vitro and in vivo at subphysiological levels. RT-PCR and Western Blot detected dysferlin mRNA and protein in AAV.DYSF.OVERLAP-transduced cells, and mRNA reached a 7-fold elevated level compared to the reference gene (GAPDH). In vivo, the experimental group showed intermediate median values for the proportion of necrotic muscle fibers, muscle fibers with internalized nuclei, and cross-sectional area of muscle fibers compared to the same parameters in the control groups of WT and Bla/J mice, although the differences were not statistically significant. The inverse relationship between the dosage and the severity of inflammatory changes in the muscles may be attributed to the decrease in the number of necrotic fibers. The share of transduced myofibers reached almost 35% in the group with the highest dose. The use of two-vector systems based on AAV is justified in terms of therapeutic efficacy. The expression of dysferlin at a subphysiological level, within a short observation period, is capable of inducing the restoration of muscle tissue structure, reducing inflammatory activity, and mitigating necrotic processes. Further research is needed to provide a more detailed assessment of the impact of the transgene and viral vector on the inflammatory component, including longer observation periods.
The synthetic approaches for the preparation of
trans
(NO,OH)-
cis
(NO
2
,NO
2
)-RuNO(L)
2
(NO
2
)
2
OH, where L = ethyl nicotinate (
I
) and methyl nicotinate (
II
), are reported. The structures of ...the complexes are characterized by X-ray diffraction and analyzed by Hirshfeld surface analysis. Both compounds show a nitric oxide release reaction under 445 or 532 nm irradiation of dimethyl sulfoxide (DMSO) solutions, which is studied by combined ultraviolet-visible- (UV-vis), infrared- (IR), and electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) calculations. The charge transfer from the OH-Ru-NO chain and nitrite ligands to the antibonding orbitals of Ru-NO is responsible for the photo-cleavage of the ruthenium-nitrosyl bond. The elimination of NO leads to a side reaction, namely the protonation of the parent hydroxyl compound. The cytotoxicity and photo-induced cytotoxicity investigations of both compounds on the breast adenocarcinoma cell line MCF-7 reveal that (
I
) and (
II
) are cytotoxic with IC
50
values of 27.5 ± 2.8 μM and 23.3 ± 0.3 μM, respectively. Moreover, (
I
) shows an increase of the toxicity after light irradiation by 7 times (IC
50
= 4.1 ± 0.1), which makes it a prominent target for deeper biological investigations.
Synthetic approaches for the preparation of
trans
(NO,OH)-
cis
(NO
2
,NO
2
)-RuNO(L)
2
(NO
2
)
2
OH (L = ethyl nicotinate (
I
) and methyl nicotinate (
II
)) are reported. Compounds show a nitric oxide release under 445 or 532 nm irradiation in solution.
The superconducting properties of hierarchical nanostructured samples of Pb–In alloys have been studied by the measurement of dynamic susceptibility χ(T) temperature dependence. Symmetric samples ...with different shapes and sizes were formed on a brass metallic net by cathode-metal electrodeposition with a programmed pulsing current. Two different kinds of χ(T) dependence were observed in synthesized structures. The first kind was a broad superconductive transition without energy dissipation with a very weak response to the external magnetic field. The second kind was, conversely, an abrupt transition signifying an energy dissipation with a significant field response. This behavior depends on the ratio between a superconducting domain size (defined by the London penetration depth λ) and a crystallite size. In these cases, one or several superconducting domains are present in a sample. This result paves the way to controlling a superconducting domain size in materials with the parameters of a pulsed current.
Aim. To evaluate the effectiveness of hardware Continuous Positive Airway Pressure therapy (CPAP therapy) and its likely predictors in patients with heart failure with preserved ejection fraction ...(HFpEF) associated with obstructive sleep apnea syndrome (OSAS).
Materials and methods. The study involved 207 men with HFpEF and OSAS (apnea/hypopnea index 15 per hour) who did not initially have ischemic disease and other structural heart pathology. At inclusion in the study, polysomnography and echocardiography were performed with an assessment of diastolic function and global longitudinal deformation of the left ventricular myocardium, as well as a 6-minute walk test (6MWT) and the level of the brain natriuretic peptide precursor (NT-proBNP) in the blood was determined. 80 patients received hardware CPAP the rapy, 127 patients made up the control group. After 12 months, 6MWT was repeated, NT-proBNP was determined, and clinical outcomes were assessed retrospectively.
Results. The CPAP group had 16% fewer hospitalizations (p=0.011 95% confidence interval – CI 4.29) and showed a trend towards an increase in the 6MWT distance (p=0.065). To assess the likely predictors of the effectiveness of CPAP therapy, a subgroup of “responders” was identified, characterized by an increase in the distance according to the 6MWT, a decrease in the level of NT-proBNP, and the absence of adverse clinical events during the observation period. There were significant differences between responders and non-responders in apnea/hypopnea index (p=0.01 95% CI -10.6; -2.5), global longitudinal deformation of the left ventricular myocardium (p=0.05 95% CI -4.7; 0), diastolic function E/A (p=0.02 95% CI -0.1; 0).
Conclusion. CPAP therapy improves clinical outcomes and functional status in patients with OSAS-associated HFpEF. The predictive model built using the identified efficacy predictors can be used to develop a personalized treatment algorithm for this cohort of patients.
Three-layer iron-rich Fe3+xSi1−x/Ge/Fe3+xSi1−x (0.2 < x < 0.64) heterostructures on a Si(111) surface with Ge thicknesses of 4 nm and 7 nm were grown by molecular beam epitaxy. Systematic studies of ...the structural and morphological properties of the synthesized samples have shown that an increase in the Ge thickness causes a prolonged atomic diffusion through the interfaces, which significantly increases the lattice misfits in the Ge/Fe3+xSi1−x heterosystem due to the incorporation of Ge atoms into the Fe3+xSi1−x bottom layer. The resultant lowering of the total free energy caused by the development of the surface roughness results in a transition from an epitaxial to a polycrystalline growth of the upper Fe3+xSi1−x. The average lattice distortion and residual stress of the upper Fe3+xSi1−x were determined by electron diffraction and theoretical calculations to be equivalent to 0.2 GPa for the upper epitaxial layer with a volume misfit of −0.63% compared with a undistorted counterpart. The volume misfit follows the resultant interatomic misfit of |0.42|% with the bottom Ge layer, independently determined by atomic force microscopy. The variation in structural order and morphology significantly changes the magnetic properties of the upper Fe3+xSi1−x layer and leads to a subtle effect on the transport properties of the Ge layer. Both hysteresis loops and FMR spectra differ for the structures with 4 nm and 7 nm Ge layers. The FMR spectra exhibit two distinct absorption lines corresponding to two layers of ferromagnetic Fe3+xSi1−x films. At the same time, a third FMR line appears in the sample with the thicker Ge. The angular dependences of the resonance field of the FMR spectra measured in the plane of the film have a pronounced easy-axis type anisotropy, as well as an anisotropy corresponding to the cubic crystal symmetry of Fe3+xSi1−x, which implies the epitaxial orientation relationship of Fe3+xSi1−x (111)0−11 || Ge(111)1−10 || Fe3+xSi1−x (111)0−11 || Si(111)1−10. Calculated from ferromagnetic resonance (FMR) data saturation magnetization exceeds 1000 kA/m. The temperature dependence of the electrical resistivity of a Ge layer with thicknesses of 4 nm and 7 nm is of semiconducting type, which is, however, determined by different transport mechanisms.
In this paper, an axial-type piezoelectric energy generator with various porosities of piezoelectric ceramics is designed and analysed. A 3D finite element model is developed by using ANSYS software. ...The porosity of piezoelectric ceramic is varied from 0 to 80% through thickness or along the length of the duralumin beam. The axial type energy harvester consists of bimorph (d31) and cylinder (d33) piezoelectric patches with base excitation. The effects of various porosities, proof mass locations, and different applied acceleration are used to determine the output voltage and power generation. The maximum output voltage and power are obtained equal to 2.25 V and 5.1 µW, respectively.
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