Theoretical treatment of the resonant hyper-Raman scattering of light in crystals

The work is aimed at discussion of different mechanisms of the resonant hyper-Raman scattering of light with participation of excitons in semiconductor crystals and analysis of their contributions to the scattering intensity.Работа посвящена обсуждению различных механизмов резонансного гиперкомбинационного рассеяния света с участием экситонов в полупроводниковых кристаллах и анализу их вкладов в интенсивность рассеяния.Роботу присвячено обговоренню різних механiзмiв резонансного гіперкомбінаційно-го розсіяння світла за участю екситонів у напівпровідникових кристалах та аналізу їх внесків в інтенсивність розсіяння

Influence of deformation on the microsructure and magneic properties of Heusler alloys

This paper presents the results of studies of the effects of deformation obtained by the method of multiple isothermal forging on the microstructure and magnetic properties of the NiMnGa alloy system. It is shown that the microstructure of the initial alloy during deformation undergoes changes, grain size decreases and a two-component structure is formed. The magnetic domain structure of the original and deformed alloys was visualized by magnetic force microscopy. It is shown that the distortion of the domain shape is associated with the presence of a martensitic relief and grain boundaries, 180-degree magnetic domains are continuous within the crystallites, while they cross the flat parallel boundaries of the martensite plates. The study of temperature and field magnetization dependences of the initial and isothermal forging samples demonstrates an insignificant magnetization decrease and a shift of the phase transition temperature toward low temperatures. It’s concluded that deformation by the isothermal forging method can be considered as a way to correct the phase transition temperature in NiMnGa alloys with preservation of magnetization

Type I-E CRISPR-cas systems discriminate target from non-target DNA through base pairing-independent PAM recognition

Discriminating self and non-self is a universal requirement of immune systems. Adaptive immune systems in prokaryotes are centered around repetitive loci called CRISPRs (clustered regularly interspaced short palindromic repeat), into which invader DNA fragments are incorporated. CRISPR transcripts are processed into small RNAs that guide CRISPR-associated (Cas) proteins to invading nucleic acids by complementary base pairing. However, to avoid autoimmunity it is essential that these RNA-guides exclusively target invading DNA and not complementary DNA sequences (i.e., self-sequences) located in the host's own CRISPR locus. Previous work on the Type III-A CRISPR system from Staphylococcus epidermidis has demonstrated that a portion of the CRISPR RNA-guide sequence is involved in self versus non-self discrimination. This self-avoidance mechanism relies on sensing base pairing between the RNA-guide and sequences flanking the target DNA. To determine if the RNA-guide participates in self versus non-self discrimination in the Type I-E system from Escherichia coli we altered base pairing potential between the RNA-guide and the flanks of DNA targets. Here we demonstrate that Type I-E systems discriminate self from non-self through a base pairing-independent mechanism that strictly relies on the recognition of four unchangeable PAM sequences. In addition, this work reveals that the first base pair between the guide RNA and the PAM nucleotide immediately flanking the target sequence can be disrupted without affecting the interference phenotype. Remarkably, this indicates that base pairing at this position is not involved in foreign DNA recognition. Results in this paper reveal that the Type I-E mechanism of avoiding self sequences and preventing autoimmunity is fundamentally different from that employed by Type III-A systems. We propose the exclusive targeting of PAM-flanked sequences to be termed a target versus non-target discrimination mechanis