Optical-luminescence properties of ZnO and TiO2 nanopowders obtained by pulsed laser reactive ablation

Journal of Materials Science: Materials in Electronics - The ZnO and TiO2 nanopowders have been prepared by means of the pulsed laser reactive ablation of metallic (Zn, Ti) targets. The Structural,...     

Heteroalleles in Common Wheat: Multiple Differences between Allelic Variants of the Gli-B1 Locus

The Gli-B1-encoded γ-gliadins and non-coding γ-gliadin DNA sequences for 15 different alleles of common wheat have been compared using seven tests: electrophoretic mobility (EM) and molecular weight (MW) of the encoded major γ-gliadin, restriction fragment length polymorphism patterns (RFLPs) (three different markers), Gli-B1-γ-gliadin-pseudogene known SNP markers (Single nucleotide polymorphisms) and sequencing the pseudogene GAG56B. It was discovered that encoded γ-gliadins, with contrasting EM, had similar MWs. However, seven allelic variants (designated from I to VII) differed among them in the other six tests: I (alleles Gli-B1i, k, m, o), II (Gli-B1n, q, s), III (Gli-B1b), IV (Gli-B1e, f, g), V (Gli-B1h), VI (Gli-B1d) and VII (Gli-B1a). Allele Gli-B1c (variant VIII) was identical to the alleles from group IV in four of the tests. Some tests might show a fine difference between alleles belonging to the same variant. Our results attest in favor of the independent origin of at least seven variants at the Gli-B1 locus that might originate from deeply diverged genotypes of the donor(s) of the B genome in hexaploid wheat and therefore might be called “heteroallelic”. The donor’s particularities at the Gli-B1 locus might be conserved since that time and decisively contribute to the current high genetic diversity of common wheat.     

Influence of the Thermal Sensitivity of Material on the Nonstationary Thermal State of a Multilayer Plate

Materials Science - The nonstationary thermal state of a thermally sensitive multilayer plate is described by a nonlinear boundary-value problem with discontinuous coefficients. The method proposed...     

X-Ray luminescence of polycrystalline TbO<Subscript>2</Subscript>-doped Li<Subscript>2</Subscript>B<Subscript>4</Subscript>O<Subscript>7</Subscript>

This paper examines the effect of doping level on the X-ray luminescence of TbO₂-doped polycrystalline lithium tetraborate. It is shown that, when interpreting such spectra, it is convenient to proceed from the terms of free activator and constituent ions. We demonstrate that the emission lines of Tb³⁺ in doped polycrystalline lithium tetraborate are effectively excited in the band between 350 and 650 nm, which is predominantly due to electron transitions from the ⁵ D ₃ and ⁵ D ₄ excited states to spin-orbital levels of the ⁷ F _J ground multiplet. The emission lines of lithium and boron in single-crystal and polycrystalline undoped lithium tetraborate are effectively excited in the band between 274 and 550 nm.     

Influence of stress concentrators on the temperature dependence of the liquid metal embrittlement of Armco iron

We study temperature dependences of the effects of liquid indium and lead-bismuth eutectics on the ultimate strength and tensile elongation of Armco iron. Tests were performed on Armco iron cylindrical specimens with stress concentrators and with square cross section under active strain with a rate of 8.3 · 10^–4 s^–1. It was found that, under identical test conditions, the decrease in the ultimate strength of the specimens with concentrators caused by the effect of melts occurs in a broader temperature range than the embrittlement of specimens without concentrators. The effect of liquid metal also depends on the size of the grains in iron (26 – 110 µm) but its character is different for specimens with and without concentrators.Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 29, No. 5, pp. 65–72, September–October, 1993.     

Demand-controlled desynchronization of oscillatory networks by means of a multisite delayed feedback stimulation

We study the potential of delayed feedback stimulation administered via multiple sites to control the synchronization and the spatio-temporal activity pattern within a network of oscillators. Two models with different levels of complexity are investigated: an ensemble of phase oscillators is used to study and analyze the effects of the stimulation in detail and a microscopic model is presented to exemplify the effectiveness of the method in terms of a stable desynchronization continuously maintained under realistic conditions. The investigation shows that depending on the spatial stimulation profile a multi-cluster state or a fully desynchronized state results. Both states are characterized by a strong suppression of the first order parameter indicating a strong desynchronization. Multisite delayed feedback stimulation realizes a demand-controlled stimulation which stabilizes the desired desynchronized state while the used stimulation current is minimized. We propose the method to be tested as a therapy of diseases characterized by pathological synchronization and for the therapy of defective neuronal pattern generators.     

Influence of Microstructure on the Strength and Cyclic Crack Resistance of Cast Irons

We study the influence of microstructure of high-strength cast irons of ferritic, ferritic-pearlitic, and pearlitic classes on the characteristics of strength and cyclic crack resistance and establish the relationship between the characteristics of strength and cyclic crack resistance and the chemical composition and microstructural parameters of the matrix and graphite inclusions of high-strength cast irons. Indeed, the ultimate strength _u = 750–850 MPa, fatigue threshold K _th = 8–10 MPa , and cyclic fracture toughness K _fc = 50–60 MPa are guaranteed by the pearlitic matrix and the following parameters of the graphite phase: the content of graphite f _p 10%, the degree of its spheroidization of about 95%, the size of globules d _gl 20–50 m, and the distance between them 40–70 m, obtained in high-strength cast irons containing (wt.%): 3.2–3.5 C, 1.9–2.5 Si, 0.35–0.4 Mn, and 0.05 Mg.