Search results for "AHN"
showing 10 items of 67 documents
A pseudo-Jahn–Teller model of the photochromic effect in sodium nitroprusside
2003
Abstract A new model for the photochromic effect in sodium nitroprusside Na2[Fe(CN)5(NO)]·2H2O based on the concept of the pseudo-Jahn–Teller effect is proposed. The model takes into account the electron transfer from the Fe2+ ion to the π* orbitals of the NO-ligand as well as the vibronic mixing of three electronic states of the Fe NO fragment through the non-symmetric and full-symmetric modes. The problem is solved within the adiabatic approximation. Under certain conditions the lower sheet of the adiabatic potential is shown to possess three minima with the increasing energies that correspond to the N-bound, sideways bound and O-bound NO group. The barriers between the minima are estimat…
Crystal structure of SrMn2(Si2O7)(OH)2 H2O, a new mineral of the lawsonite type
1992
Crystal with the composition SrMn 2 [Si 2 O 7 ](OH) 2 .H 2 O were found in a sugilite, serandite-pectolite rich sample from the Wessels Mine, Kalahari, South Africa. The crystal structure of the nex compound with space group Cmcm, a = 6.255(1), b = 9.034(2), c = 13.397(2) A, Z = 4 was determined from X-ray single-crystal data (R = 0.048). The structure is of the lawsonite type where Al is completely replaced by Mn 3+ and Ca by Sr. [Mn 3+ O 6 ] octahedra forming edge-sharing chains parallel to a exhibit a Jahn-Teller distortion with four short and two long Mn 3+ -O distances. Sr is in eight-fold coordination and H 2 O is disordered on a split position. Together with orientite, macfallite, ru…
Mn3+ in garnets III. Absence of Jahn-Teller distorition in synthetic Mn3+-bearing garnet
1985
The crystal structure of a ternary Mn3+-bearing garnet, close to the composition Gross34 Spess26 CaMnGt40 has been refined to a weighted R-value of 0.051 for 440 unique reflections. The lattice constant is 11.867(1) A, fractional atomic parameters for oxygen are x=0.0374 (2), y=0.0470 (2), and z=0.6532 (2). Refinement of site occupancies gave 0.81 (3) Ca+0.19 (3) Mn2+ in the eight coordinated site 24c and 0.64 (2) Al+0.36 (2) Mn3+ in the octahedral site 16a. No deviation from the cubic space group Ia3d has been observed, the Mn3+-bearing YO6 octahedron is nearly regular. Thus, the presence of the 3d 4-configurated ion Mn3+ does not cause Jahn-Teller distortion in this garnet structure.
Exome sequencing in a child with neurodevelopmental disorder and epilepsy: Variant analysis of the AHNAK2 gene
2022
Background The AHNAK2 gene encodes a large nucleoprotein expressed in several tissues, including brain, squamous epithelia, smooth muscle, and neuropil. Its role in calcium signaling has been suggested and to date, clear evidence about its involvement in the pathogenesis of clinical disorders is still lacking. Methods Here, we report a female 24-year-old patient diagnosed with a cardio-facio-cutaneous-like phenotype (CFC-like), characterized by epilepsy, psychomotor development delay, atopic dermatitis, congenital heart disease, hypotonia, and facial dysmorphism, who is compound heterozygote for two missense mutations in the AHNAK2 gene detected by exome sequencing. Results This patient had…
Louis Kahn. Lo zeitgeist del secondo dopoguerra
2020
The essay concerns the reception by some young architects and by the following generations of the work of Louis Kahn. It is focused to the way the principle of monumentality and of abstraction can be used in architectural design
Intenzionalità collettiva, ontologia sociale e mindreading
2014
In his Collective Intentions and Actions John Searle argued that having a preintentional sense of others as at least potentially cooperative agents “like me” is a necessary condition of collective intentionality. He also argued, in Rationality in Action, that understanding others qua intentional agents necessarily presupposes rationality because rational constraints are built into the logical structure of intentional phenomena. In this paper we will try to specify further these claims in the light of current debate on mindreading, where other-understanding is spelled out either in terms of automatic, subpersonal simulative mechanisms, or in terms of normative, rational principles. We will a…
Jahn-Teller effect in molecular electronics: quantum cellular automata
2017
The article summarizes the main results of application of the theory of the Jahn-Teller (JT) and pseudo JT effects to the description of molecular quantum dot cellular automata (QCA), a new paradigm of quantum computing. The following issues are discussed: 1) QCA as a new paradigm of quantum computing, principles and advantages; 2) molecular implementation of QCA; 3) role of the JT effect in charge trapping, encoding of binary information in the quantum cell and non-linear cell-cell response; 4) spin-switching in molecular QCA based on mixed-valence cell; 5) intervalence optical absorption in tetrameric molecular mixed-valence cell through the symmetry assisted approach to the multimode/mul…
Jahn-Teller distortion aroundFe4+inSr(FexTi1−x)O3−δfrom x-ray absorption spectroscopy, x-ray diffraction, and vibrational spectroscopy
2007
$\mathrm{Sr}({\mathrm{Fe}}_{x}{\mathrm{Ti}}_{1\ensuremath{-}x}){\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}}$ perovskites (strontium titanate ferrite solid solution) with well-defined oxygen stoichiometry have been studied as a function of iron concentration by x-ray diffraction, Fe and Ti $K$-edge x-ray absorption spectroscopy (XAS), and vibrational (Raman and infrared) spectroscopy. In reduced $\mathrm{Sr}({\mathrm{Fe}}_{x}{\mathrm{Ti}}_{1\ensuremath{-}x}){\mathrm{O}}_{3\ensuremath{-}x∕2}$ samples, the analysis of the Fe $K$-edge extended x-ray absorption fine structure indicates the expected presence of oxygen vacancies ${\mathrm{V}}_{\mathrm{O}}^{∙∙}$ in the first coordination shell…
The Hamilton–Jacobi Equation
2001
We already know that canonical transformations are useful for solving mechanical problems. We now want to look for a canonical transformation that transforms the 2N coordinates (q i , p i ) to 2N constant values (Q i , P i ), e.g., to the 2N initial values \((q_{i}^{0},p_{i}^{0})\) at time t = 0. Then the problem would be solved, q = q(q0, p0, t), p = p(q0, p0, t).
Evidence for Photoinduced Hole Coupling in BaTiO3:Co
1995
A possible photoinduced correlation mechanism in BaTiO 3 : Co is described. The underlying microscopic process is a local hole photoinjection at a Co 3+ site close to a preexisting metastable hole, The Jahn-Teller field at the Co 2+ site transfers this pair of holes in the next cell along the rhombic direction [111] before normal polaronic or band conduction. The spatial extension of this correlation depends on a characteristic «delocalization» length. This unstable conductive state appears to be possibly frozen in a permanent way below T c