Superconductivity in LaT(M)BN and La3T(M2)B2N3 (T(M) = transition metal) synthesized under high pressure.

Various layered boronitrides (LaN)(n)(T(M2)B(2)) (T(M) = transition metal; n = 2, 3) have been prepared using a high-pressure synthesis technique in which an inverse α-PbO-type T(M2)B(2) layer is separated by two or three rock salt-type LaN layers and these layers are connected through linear (BN) units. The electronic states of the distinguishing (BN) unit and intermediate rock salt-type LaN layer are discussed on the basis of density functional theory calculations. Bulk superconductivity has been found in LaNiBN (T(c) ≈ 4.1 K), CaNiBN (T(c) ≈ 2.2 K), and LaPtBN (T(c) ≈ 6.7 K), where the Fermi level E(F) is located in the bands composed of the T(M)(d)-B(2p) antibonding state and the main T(M)(d) band resides well below E(F). The non-superconductive T(M)-based compounds exhibit Pauli paramagnetic behavior, in which the highly itinerant nature of the electrons caused by strong T(M)(d)-B(2p) covalent bonding suppresses the long-range magnetic ordering.

Dioxygen activation and substrate oxygenation by a p-nitrothiophenolatonickel complex: unique effects of an acetonitrile solvent and the p-nitro group of the ligand.

The nickel(II) complex [Ni(Tp(Me2)) (SC(6)H(4)NO(2))] [1a; Tp(Me2) = hydrotris(3,5-dimethylpyrazol-1-yl)borate] reacts with O(2) to form the ligand oxygenation product ArSO(2)(-) in MeCN, and also 1a catalyzes the oxygenation of external substrates such as triphenylphosphine. The reactivity may correlate to the unique quinoid-like resonance structure of the thiophenolate ligand. The structure is stabilized by a p-nitro group and induced by coordination of MeCN.

Square coordinated MnO(2)-units in BiMn(7)O(12).

Room temperature high-resolution synchrotron X-ray diffraction (HRSXRD) measurements were carried out on polycrystalline samples of BiMn(7)O(12) and LaMn(7)O(12). Rietveld refinements of HRSXRD data describe the crystal structures of both compounds in the monoclinic space group I2/m. The maximum entropy method-based pattern fitting (MPF) method inversion of HRSXRD data was utilized to obtain the spatial electron density (ED) distribution. Obtained results show clear differences in ED distributions around Mn-O bonds between isomorphic BiMn(7)O(12) and LaMn(7)O(12). The scheme of ED distributions in BiMn(7)O(12) indicates the presence of orbital ordering in the MnO(2) planar arrangement that appears as prominent features in very distorted MnO(12) and MnO(6) polyhedrons in the perovskite related structure of [BiMn(3)](A-site)[Mn(4)](B-site)O(12).

Three cases of acute sterile corneal melt after cataract surgery.

PURPOSE: To report three cases of acute sterile corneal melt after cataract surgery. OBSERVATIONS: Case 1 was a 21-year-old male presenting with a corneal perforation of his right eye at 10 days after cataract surgery. Case 2 was a 67-year-old male who developed a corneal melt in his left eye at 15 days after cataract surgery. Case 3 was a 70-year-old female with a corneal melt of her left eye at 7 days after cataract surgery. None of the cases exhibited any signs of infection. Topical nonsteroidal anti-inflammatory drug use, dry eye, systemic autoimmune diseases, and/or a combination of these were present in patients who developed corneal melt after cataract surgery. CONCLUSIONS AND IMPORTANCE: Corneal melt cases can occur early after cataract surgery, thereby leading to corneal thinning and perforation.

Positive and negative magnetodielectric effects in A-site ordered (BiMn3)Mn4O12 perovskite.

A-site ordered perovskite (BiMn3)Mn4O12 was synthesized through a high-pressure synthesis route at 5 GPa and found to exhibit two magnetic transitions and to show either a positive or a negative magnetodielectric effect depending on the temperature range/magnetic state.

Conjunctival swabs and corneoscleral rim cultures from corneal transplantation donors as possible early indicators for posttransplant endopthalmitis.

PURPOSE: To determine by microbiological examinations the rate of conjunctiva and corneoscleral rim contamination of cadaver donor tissues. METHODS: A prospective review of culture results for 98 cadaver donor conjunctival swabs [mean age 76.4 ± 12.9 years (±SD)]. Transplant patients were evaluated both before and after disinfection with gentamicin. Individual parameters evaluated included detection rates of bacteria, variety of detected bacteria, time interval from donor death to tissue harvest and age of donors. RESULTS: Before disinfection, 60 out of 98 conjunctival swabs exhibited microbial growth, while only 36 out of 98 exhibited growth after disinfection (p = 0.0006). Longer intervals between death and tissue harvest were associated with higher positive microbial growth rates. Prior to disinfection, culture-positive donors (74.1 ± 13.6 years) were significantly younger than culture-negative donors (79.8 ± 10.8 years) (p = 0.024). Positive donor rim cultures were noted in 2 out of the 22 corneal transplantations. Microorganisms isolated from the corneal grafts matched those found in the conjunctiva. CONCLUSIONS: It is recommended that the corneoscleral buttons be removed as soon as possible. Cultures of conjunctival swabs collected from donors after disinfection may be useful in determining treatment for postoperative infections occurring after corneal transplantation.