Investigation of the Crystal Structure of PrCu 2 Ge 2 Compound.

Методом монокристала (дифрактометр Stoe IPDS ІІ, Mo K-випромінювання) вивчено кристалічну структуру сполуки PrCu2Ge2 (структурний тип СeGa2Al2, пр. гр. I4/mmm, символ Пірсона tI10, a = 4,3986(11) Å, c = 10,6364(7) Å, RF = 0,0622; RW = 0,0964; Goof = 1,03). Проаналізовано структурні взаємозв’язки дослідженої сполуки з окремими бінарними та тернарними германідами, що утворюються при 870 K у системі Pr–Cu–Ge. The crystal structure of PrCu2Ge2 compound was studied by single crystal method (diffractometer Stoe IPDS ІІ, Mo K-radiation, structure type СeGa2Al2, space group I4/mmm, Pearson code tI10, a = 4,3986(11) Å, c = 10,6364(7) Å, RF = 0,0622; RW = 0,0964; Goof = 1,03). The structural interrelations between studied compound and some binary and ternary phases which form at 870 K in the Pr–Cu–Ge system were discussed

Genetic approaches to understanding the causes of stuttering

Stuttering is a common but poorly understood speech disorder. Evidence accumulated over the past several decades has indicated that genetic factors are involved, and genetic linkage studies have begun to identify specific chromosomal loci at which causative genes are likely to reside. A detailed investigation of one such region on chromosome 12 has identified mutations in the GNPTAB gene that are associated with stuttering in large families and in the general population. Subsequent studies identified mutations in the functionally related GNPTG and NAGPA genes. Mutations in these genes disrupt the lysosomal targeting pathway that generates the Mannose 6-phosphate signal, which directs a diverse group of enzymes to their target location in the lysosome of the cell. While mutations in these three genes can be identified in less than 10% of cases of familial stuttering, this knowledge allows a variety of new studies that can help identify the neuropathology that underlies this disorder

Band structure, density of states, and crystal chemistry of ZrGa2 and ZrGa3 single crystals

Using FP-LAPW Method we have performed calculations of the band structure of the ZrGa2 and ZrGa3 crystals. The all-electron full potential linearized augmented plane wave method was used to solve the Kohn Sham DFT equations. We have explored different approximations using three kinds of exchange-correlation potentials on the electronic structure and we concluded that there is insignificant influence on the band structure and the density of states. It is clear that there exists a difference in the band dispersion with one move from ZrGa2 to ZrGa3 that is attributed to the fact that ZrGa2 has four formula per unit cell (Z = 4) while ZrGa3 has two formula per unit cell (Z = 2). Despite some similarity in the crystallochemistry of ZrGa2 to ZrGa3 some differences are observed in the band structure dispersion. There is a strong hybridization between the states. The interaction of charges between Zr and Ga atoms is due to the strong hybridization, and the covalent bond arises due to the degree of hybridization. Hence, there is a strong covalent bonding between these atoms. We have obtained a space electron charge density distribution in the average unit cell by calculations of the electron charge density distribution. The space electronic charge density contour distribution is illustrated in (1 0 0) and (1 1 0) planes