In GaAs nanowires grown along the cubic 111c direction, zinc blende and wurtzite arrangements have been observed in their stacking sequence, since the energetic barriers for nucleation are typically ...of similar order of magnitude. It is known that the interplanar spacing of the (111)c Ga (or As) planes in the zinc blende polytype varies slightly from the wurtzite polytype. However, different values have been reported in the literature. Here, the ratio of the interplanar spacing of these polytypes is extracted based on X‐ray diffraction measurements for thin GaAs nanowires with a mean diameter of 18–25 nm. The measurements are performed with a nano‐focused beam which facilitates the separation of the scattering of nanowires and of parasitic growth. The interplanar spacing of the (111)c Ga (or As) planes in the wurtzite arrangement in GaAs nanowires is observed to be 0.66% ± 0.02% larger than in the zinc blende arrangement.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The strain profile of an individual Cu(In,Ga)Se2 nanocrystallite in a solar cell absorber layer is accessed using synchrotron radiation. We find that the investigated crystallite is inhomogeneously ...strained. The strain is most likely produced by a combination of intergranular strain and composition variations in nanocrystals inside the polycrystalline semiconductor film and carries information about the intercrystalline interaction. The measurements are made nondestructively and without additional sample preparation or x-ray beam nanofocusing. This is the first step towards measurements of strain profiles of individual crystallites inside a working solar cell.
A review on the growth and characterization of site‐selective quantum dots (QDs) is presented. First, a theoretical model is used to describe the mechanism leading to the formation of QDs at ...pre‐defined locations. The structural properties of site‐selective QDs was revealed and their optical quality was tested. Various parameters, such as hole size, hole depth, or InAs amount, influencing the QD occupation and the QD size are discussed and possible ways to control these are presented.
Ordered QD array with multiple dot nucleation (left) and single QD in dry etched hole (right).
In this Feature Article, mechanisms that control the structure and the distribution of site‐selective InAs quantum dots (QDs) grown on pre‐patterned GaAs substrates are reviewed. Depending on the application, regular arrays with multiple QDs (upper left figure) or individual QDs at pre‐defined locations (upper right figure) are of interest. Besides geometrical parameters of the pattern and growth parameters that determine the final QD structure to some extent, a post growth treatment based on in situ annealing has allowed to manipulate the size of QDs as well as the number of QDs per site on an array (lower figure).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Helfrich et al. (pp. 2387–2401) have prepared and investigated site‐selective InAs quantum dots (QDs) on pre‐patterned GaAs substrates in order to gain further understanding of the mechanisms ...controlling the structure and the distribution of site‐selective QDs. Regular arrays with multiple QDs (upper left image on the cover) or individual QDs at pre‐defined locations (upper right) are of interest, depending on the envisaged applications. Besides geometrical parameters of the pattern and growth parameters that determine the final QD structure to some extent, a post growth treatment based on in situ annealing has allowed to manipulate the size of the QDs as well as the number of QDs per site in an array (lower left). Further insight was gained by analyzing a single array of site‐selective QDs grown inside nanoholes with X‐ray diffraction techniques. The structure and the periodicity of the holes is revealed in the measurement and can be modeled using finite element method (lower right). A proper understanding of the contributions from hole shape and pattern is essential in order to further investigate the ordering of QDs nucleating inside regularly spaced holes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Background. In the context of the pandemic, the demand for non-invasive diagnostics of patients using pulse oximeters has increased, and telemedicine technologies have also received significant ...development. Given these trends, the authors set themselves the goal of analyzing the principles of operation of modern devices for non-invasive health diagnostics and identifying opportunities for their improvement. Materials and methods. The authors conducted a study in the field of patent activity, studied the principles of operation of a number of foreign devices. Results. As a result of the work carried out, it was possible to come to the conclusion that the proposed devices in the field of non-invasive diagnostics are obsolete and do not meet the requirements of modern customers: mounting the probe on the fingers excludes the possibility of using devices by a number of patients, for example, those suffering from Raynaud's disease, and the lack of wireless data transmission reduces comfort of use. Conclusions. The authors propose to pay attention to the concept of an ear pulse oximeter, which makes it possible to provide comfortable non-invasive diagnostics of patients using wireless communication and automatic data processing methods.
Currently, there are no effective drugs for the treatment of amyotrophic lateral sclerosis (ALS). Only two drugs—edaravone and riluzole—have been approved, but they have very limited efficacy. The ...aim of this work was to modify the structural core of the Edaravone—phenylpyrazolone moiety and combine it with aminoadamantane pharmacophore in order to expand the spectrum of its action to a number of processes involved in the pathogenesis of ALS. New conjugates of edaravone derivatives with 1-aminoadamantanes combined with alkylene or hydroxypropylene spacers were synthesized, and their biological activity was investigated. Compounds were found that could inhibit lipid peroxidation and calcium-related mitochondrial permeability, block fast sodium currents of CNS neurons, and reduce aggregation of the mutated form of the FUS-protein typical to ALS. So, the proposed modification of the edaravone molecule has allowed the obtaining of new original structures that combine some prospective therapeutic mechanisms against key chains of the pathogenesis of ALS. The identified lead compounds can be used for further optimization and development of new promising drugs on this basis for the treatment of ALS.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The complexes Pt(tpp) (H2tpp=tetraphenylporphyrin), M(acac)2 (M=Pd, Pt, Hacac=acetylacetone), and Pd(ba)2 (Hba=benzoylacetone) were co‐crystallized with highly electron‐deficient arene systems to ...form reverse arene sandwich structures built by π‐hole⋅⋅⋅MII (d8M=Pt, Pd) interactions. The adduct Pt(tpp)⋅2 C6F6 is monomeric, whereas the diketonate 1:1 adducts form columnar infinity 1D‐stack assembled by simultaneous action of both π‐hole⋅⋅⋅MII and C⋅⋅⋅F interactions. The reverse sandwiches are based on noncovalent interactions and calculated ESP distributions indicate that in π‐hole⋅⋅⋅MII contacts, MII plays the role of a nucleophile.
Role reversal: Square‐planar platinum(II) and palladium(II) systems with π hole‐donating polyfluoroaromatic species give a family of reverse sandwich structures based on noncovalent interactions in which the charge distribution at the metal center and at arenes is opposite to that of classic sandwich species.
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The paper proposed a new porous material for wound healing based on chitosan and C-phycocyanin (C-PC). In this work, C-PC was extracted from the cyanobacteria Arthrospira platensis biomass and ...purified through ammonium sulfate precipitation. The obtained C-PC with a purity index (PI) of 3.36 ± 0.24 was loaded into a chitosan sponge from aqueous solutions of various concentrations (250, 500, and 1000 mg/L). According to the FTIR study, chitosan did not form new bonds with C-PC, but acted as a carrier. The encapsulation efficiency value exceeded 90%, and the maximum loading capacity was 172.67 ± 0.47 mg/g. The release of C-PC from the polymer matrix into the saline medium was estimated, and it was found 50% of C-PC was released in the first hour and the maximum concentration was reached in 5–7 h after the sponge immersion. The PI of the released C-PC was 3.79 and 4.43 depending on the concentration of the initial solution.
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