Effect of gallium on the electrical properties and photoresponse of CuIn<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ga<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript>2</Subscript> films

Semiconducting films of CuIn_{1 − x} Ga _x Se₂ solid solutions have been produced on CdS by selenizing metallic layers in flowing nitrogen. We have optimized the film growth conditions and investigated the structure, electrical properties, energy band structure, and photoconversion quantum efficiency of the films. With increasing gallium content, the band gap of the CuIn_{1 − x} Ga _x Se₂ (x = 0, 0.2, 0.25, 0.30) films increases, reaching 1.27 eV. The films are potentially attractive for use in high-efficiency solar cells.     

Photoluminescence and excitation features of Nd<Superscript>3+</Superscript> ions in (La<Subscript>0.97</Subscript>Nd<Subscript>0.03</Subscript>)<Subscript>2</Subscript>S<Subscript>3</Subscript> · 2Ga<Subscript>2</Subscript>O<Subscript>3</Subscript> glasses

A combined study of the spectral photoluminescence distribution and excitation spectra of photoluminescence in La₂S₃ · 2Ga₂O₃ and (La_0.97Nd_0.03)₂S₃ · 2Ga₂O₃ glasses, along with the study of the transmission spectra of these glasses, was carried out. The radiative channel was ascertained to be the main channel for the energy transfer from the host matrix to the Nd³⁺ ions upon excitation of the glasses with light at a wavelength of the fundamental absorption band. Oxygen centers with the level E _c -2.0 eV act as sensitizing agents. The structural disordering of the glass host increases the variance in the magnitude of splitting of the multiplet levels from the 4f electronic states of the Nd³⁺ ion. This promotes nonradiative relaxation of the electrons from excited states to the laser ⁴F_3/2 level. The (La_0.97Nd_0.03)₂S₃ · 2Ga₂O₃ glasses can be considered as promising laser materials for obtaining the stimulated emission of radiation of Nd³⁺ ions under an optical pump in the range of the fundamental absorption band of the glass.     

The Dynamics of β-Amyloid Proteoforms Accumulation in the Brain of a 5xFAD Mouse Model of Alzheimer’s Disease

Alzheimer’s disease (AD) is the leading cause of dementia among the elderly. Neuropathologically, AD is characterized by the deposition of a 39- to 42-amino acid long β-amyloid (Aβ) peptide in the form of senile plaques. Several post-translational modifications (PTMs) in the N-terminal domain have been shown to increase the aggregation and cytotoxicity of Aβ, and specific Aβ proteoforms (e.g., Aβ with isomerized D7 (isoD7-Aβ)) are abundant in the senile plaques of AD patients. Animal models are indispensable tools for the study of disease pathogenesis, as well as preclinical testing. In the presented work, the accumulation dynamics of Aβ proteoforms in the brain of one of the most widely used amyloid-based mouse models (the 5xFAD line) was monitored. Mass spectrometry (MS) approaches, based on ion mobility separation and the characteristic fragment ion formation, were applied. The results indicated a gradual increase in the Aβ fraction of isoD7-Aβ, starting from approximately 8% at 7 months to approximately 30% by 23 months of age. Other specific PTMs, in particular, pyroglutamylation, deamidation, and oxidation, as well as phosphorylation, were also monitored. The results for mice of different ages demonstrated that the accumulation of Aβ proteoforms correlate with the formation of Aβ deposits. Although the mouse model cannot be a complete analogue of the processes occurring in the human brain in AD, and several of the observed parameters differ significantly from human values supposedly due to the limited lifespan of the model animals, this dynamic study provides evidence on at least one of the possible mechanisms that can trigger amyloidosis in AD, i.e., the hypothesis on the relationship between the accumulation of isoD7-Aβ and the progression of AD-like pathology.     

Electronic structure of carbynes studied by Auger and electron energy loss spectroscopy

The experimental carbon Auger lineshape for two samples of carbyne has been obtained. The electronic structure of carbynes has been calculated by the self-deconvolution of experimental Auger spectra. Results are discussed in terms of the electronic properties of linear molecules with 2–6 carbon atoms. It is shown that both carbyne samples have a linear structure with cumulene-type bonds but with different numbers of atoms in the chain. The influence of annealing at T < 600°C on the carbyne structure has been studied. The electron energy loss spectrum of carbynes is analyzed.     

Occurrence of Hexacosapolyenoic Acids 26:7(n‐3), 26:6(n‐3), 26:6(n‐6) and 26:5(n‐3) in Deep‐Sea Brittle Stars from Near the Kuril Islands

Significant amounts of polyunsaturated fatty acids (PUFA) with a chain length of 26 carbon atoms were detected in lipids of five deep water species of Ophiuroidea besides common fatty acids with chain lengths between 14 and 24. By means of hydrogenation, GC–MS of the methyl esters, and 4,4‐dimethyloxazoline (DMOX) derivatives of these C26 acids were characterized as 5,8,11,14,17,20,23‐hexacosaheptaenoic [26:7(n‐3)]; 8,11,14,17,20,23‐hexacosahexaenoic [26:6(n‐3)]; 5,8,11,14,17,20‐ hexacosahexaenoic [26:6(n‐6)]; and 11,14,17,20,23‐hexacosapentaenoic [26:5(n‐3)]. Concentrations of these acids varied from 0.3 to 4.5 mol% of the total FA. In all the samples investigated, the main component of C26PUFA was hexacosaheptaenoic acid 26:7(n‐3). These C26PUFA are localized mainly in polar lipids. The presence of the possible biosynthesis precursors suggests that the C26PUFA are produced by the brittle stars, and are not accumulated from food sources. This finding can also explain the presence of small amounts of the 26:7(n‐3) acid detected earlier in flesh lipids of the roughscale sole Clidoderma asperrimum, which feeds on deep water brittle stars. We suggest a possible scheme of the biosynthesis of C26 PUFA.     

Composition and Microstructure of AIVTe–B2IIITe3 Eutectic Alloys

A^IVTe–B₂ ^IIITe₃ eutectic alloys were synthesized, and their microstructure was analyzed. Attempts to prepare aligned eutectics by directional solidification resulted in anomalous eutectics, which is attributable to the polymorphism of the phases involved.