Magnetic memory effect in ZnO single crystals

Hardening of ZnO single crystals is found to occur after their treatment in a constant magnetic field (B = 1–2 T). A maximum increase in the microhardness of the crystals is observed within 3–4 h after magnetic treatment. Then, the effect gradually decreases and the microhardness regains its initial value in 2–3 days. It is revealed that the sensitivity of the microhardness to a variation in the magnetic field has a threshold character: the effect appears at a magnetic induction higher than a critical value, rapidly increases in a narrow magnetic field range ΔB (～0.3 T), and then reaches saturation. It is shown that the magnitude of the effect depends on the orientation of the magnetic field with respect to the polar axis of symmetry of the crystal and is independent of the crystallographic orientation of the measurement plane. The maximum increase in the microhardness (～20%) is observed for all the (0001), (11\(\bar 2\)0), and (10\(\bar 1\)0) faces studied in the magnetic field B ∥ [10\(\bar 1\)0]. No change in the microhardness is found to occur in the magnetic field direction B ∥ [0001]. A physical model related to the spin-dependent variations in the impurity subsystem of the crystal in the magnetic field is proposed.     

Electrical and photoelectrical behaviour of heterojunctions based on novel oligomeric metal complexes

Naringenin‐based Schiff base ligands with 4‐aminobenzoic hydrazide were obtained as a unilateral form ( L¹ ). The ligand was oligomerized by oxidative polycondensation reaction with NaOCl as an oxidant in an aqueous alkaline medium at 90 °C to form a functional oligomer ( L² ), and its transition metal complexes such as those with Cu(II), Ni(II) and Zn(II) were prepared. The monomer and the oligomeric compounds were characterized using various techniques. Optical and electrical properties of the complexes were also investigated. All compounds showed indirect band gaps and they can be accepted as being in the semiconductor class. Organic–inorganic hybrid devices were obtained using n‐Si inorganic semiconductor and the complexes. The characteristic parameters of the devices were determined using current–voltage (I–V) and capacitance–voltage measurements in the dark. Photoelectrical properties of the devices were investigated using I–V measurements under a solar simulator with an AM1.5 global filter. Copyright © 2015 John Wiley & Sons, Ltd.     

Somehow emancipating Probabilistic Evolution Theory (PREVTH) from singularities via getting single monomial PREVTH

This paper deals with the combination of the evolver dynamics of a hydrogen-like quantum system with the conical PREVTH (Probabilistic Evolution Theory) and excessively with the single monomial PREVTH. The new original applications are degree escalations in each monomial of a set of Poisson Bracket equations with multinomial right hand side and arbitrary, optimisable, parameters insertion to the resulting single monomial via an approach based on commutativity relations amongst the system basis operators. What we have shown that the additions based on commutativities with the Constancy Adding Space Extension (CASE) operator which is in fact proportional to identity operator, does not contribute to the suppression of the norm square of the single monomial coefficient matrix. This is just an observation for a specific family of systems but may be signaling a more general reality. If so it needs rather a rigorous proof.     

Preparation and characterization of alumina-zirconia composite material with different acid ratios by the sol-gel method

Alumina-zirconia composite materials were produced with different acid ratios by the sol-gel method using aluminum isopropoxide and zirconium chloride. The composites were produced by changing acid/alkoxside ratio in alumina. The composite materials were calcinated at 600°C, 900°C and 1300°C. The effects of acid concentration and calcination temperature on the surface area and pore radius were determined from the nitrogen adsorption isotherm at 77 K. The density of the composites was also measured. The minimum density of produced material was recorded as 1.35 g cm⁻³ at an acid/alkoxside ratio of 0.2. The highest specific surface area and pore diameter of the lightest material are 191.86 m² g⁻¹ and 18.4 Ǻ, respectively. Although pore diameter and specific surface area are not changed at any of the experimental temperatures which were tested by decreasing acid/alkoxside ratio, the density is slightly increased. However, it was observed that the calcination temperature significantly affects the surface area and density of the material.      

Cyclometallated Pt(II) and Pd(II) complexes with a trithiacrown ligand

We report the synthesis and full characterization for a series of cyclometallated complexes of Pt(II) and Pd(II) incorporating the fluxional trithiacrown ligand 1,4,7-trithiacyclononane ([9]aneS3). Reaction of [M(C insertion mark N)(micro-Cl)]2 (M = Pt(II), Pd(II); C insertion mark N = 2-phenylpyridinate (ppy) or 7,8-benzoquinolinate (bzq)) with [9]aneS3 followed by metathesis with NH4PF6 yields [M(C insertion mark N)([9]aneS3)](PF6). The complexes [M(C insertion mark P)([9]aneS3)](PF6) (M = Pt(II), Pd(II); Cinsertion markP = [CH2C6H4P(o-tolyl)2-C,P]-) were synthesized from their respective [Pt(C insertion mark P)(micro-Cl)]2 or [Pd(C insertion mark P)(micro-O2CCH3)]2 (C insertion mark P) starting materials. All five new complexes have been fully characterized by multinuclear NMR, IR and UV-Vis spectroscopies in addition to elemental analysis, cyclic voltammetry, and single-crystal structural determinations. As expected, the coordinated [9]aneS3 ligand shows fluxional behavior in its NMR spectra, resulting in a single 13C NMR resonance despite the asymmetric coordination environment of the cyclometallating ligand. Electrochemical studies reveal irreversible one-electron metal-centered oxidations for all Pt(II) complexes, but unusual two-electron reversible oxidations for the Pd(II) complexes of ppy and bzq. The X-ray crystal structures of each complex indicate an axial M-S interaction formed by the endodentate conformation of the [9]aneS3 ligand. The structure of [Pd(bzq)([9]aneS3)](PF6) exhibits disorder in the [9]aneS3 conformation indicating a rare exodentate conformation as the major contributor in the solid-state structure. DFT calculations on [Pt([9]aneS3)(ppy)](PF6) and [Pd([9]aneS3)(ppy)](PF6) indicate the HOMO for both complexes is primarily dz2 in character with a significant contribution from the phenyl ring of the ppy ligand and p orbital of the axial sulfur donor. In contrast, the calculated LUMO is primarily ppy pi* in character for [Pt([9]aneS3)(ppy)](PF6), but dx2-y2 in character for [Pd([9]aneS3)(ppy)](PF6).     

Cluster self-organization of silicate and germanate systems: Suprapolyhedral precursor clusters and self-assembly of orthotetrahedral structures in Na,TR-germanates (silicates)

The geometrical and topological analysis of all known types of the orthotetrahedral structures of Na,TR-germanates and their silicon analogues has been carried out using computer methods (TOPOS 4.0 program package). The full 3D reconstruction of the self-assembly mechanism of crystal structures has been performed as follows: precursor cluster-primary chain-microlayer-microframework (supraprecursor). For Na₂HLaSiO₅, NaHo₄(GeO₄)₂O₂OH, NaScGeO₄, and NaSm₃Ge₂O₈(OH)₂, the same type of 2D TR, T-network has been recognized: 433334 + T 4433. For Na₂HScGeO₅, network TR 44444 + T 444 has been recognized. The coordination number (CN) of a precursor cluster in 2D networks is six. In all structures, the invariant type of cyclic four-polyhedral precursor clusters built of tetrahedron-linked TR-polyhedra has been identified with CNs being eight, seven, or six. In the Na₅Y₄Si₄O₁₆F structure, a tubular-type primary chain in which precursor clusters are tetrahedron-linked TR polyhedra with CN = 8 has been recognized. Their stacking in a layer is characterized by the network TR 8 8 4 + T 8 4 8, where 8 corresponds to the cross section of the primary chain. In a 3D network, the total number of neighboring tubular primary chains linked to the main chain is four. In the structures with TR: T = 1: 1 or 1.5: 1, the positions above and below the center of the precursor cluster are occupied by Na atoms; in NaHo₄(GeO₄)₂O₂(OH), where TR: T = 2: 1, these positions are occupied by an Na atom and a TR atom.     

Synthesis of bicyclo[2.2.2]octane-2,3,5,6,7,8 hexols (Bishomoinositols) as glycosidase inhibitors

For the construction of the bicyclo[2.2.2]octane skeleton, 2,2-dimethyl-3a,7a-dihydro-1,3-benzodioxole was reacted with vinylene carbonate to give two isomeric cycloadditon products having the bicyclo[2.2.2]octane skeleton. Hydrolysis of the ketal ring and the opening of the carbonate functionality, followed by hydroxylation of the remaining double bond resulted in the formation of a symmetrical hexol. Epoxidation of the double bond in the cycloaddition products and the subsequent ring-opening reactions produce two additional hexol derivatives. One of the synthesized molecules exhibited enzyme-specific inhibition against alpha-glycosidase.