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1.  Stacking faults and superstructures in a layered brownmillerite 
Stacking faults in Ca4Fe2Mn0.5Ti0.5O9 have been examined using X-ray diffraction and high-resolution transmission electron microscopy. Electron diffraction revealed two superstructures with ordered stacking sequences.
Single crystals of Ca4Fe2Mn0.5Ti0.5O9 have been synthesized using a flux method. The structural characterization using single-crystal X-ray diffraction revealed the space group Amma and unit-cell dimensions of a = 5.3510 (6), b = 26.669 (3), c = 5.4914 (6) Å. The structure is isotypic with Sr3NdFe3O9 [Barrier et al. (2005 ▶). Chem. Mater. 17, 6619–6623] and exhibits separated brownmillerite-type layers. One-dimensional diffuse scattering shows that the unit cell is doubled along c by alternating the intra-layer order of tetrahedral chains, causing stacking faults along the b direction. A computer simulation was performed, proving that the observed intensity variations along the diffuse scattering rods originates from two different local structures depending on the configuration of the tetrahedral chains. Selected-area electron diffraction experiments exhibit well ordered regions characterized by satellite reflections corresponding to two different superstructures. Both superstructures can be described using the superspace group A21/m(0βγ)0s, with γ = 0.5 and β ≃ 0.27 or β = 0.
PMCID: PMC3222140  PMID: 22101537
layered brownmillerite; diffuse scattering; stacking faults; modulated structure
2.  Investigation of potential interaction of ciprofloxacin with cyclosporine in bone marrow transplant recipients. 
The effect of the 4-quinolone antimicrobial agent ciprofloxacin on the concentration in plasma and the pharmacokinetics of the immunosuppressive agent cyclosporine was studied in 10 bone marrow transplant recipients. There were no statistically or clinically significant changes in cyclosporine trough concentrations or areas under the concentration-time curve following oral doses of 500 mg of ciprofloxacin every 12 h for 4 days. The data suggest a lack of relevant pharmacokinetic interaction of ciprofloxacin with cyclosporine. There was no indication of an enhanced nephrotoxicity for this drug combination.
PMCID: PMC171756  PMID: 2203301
3.  Pulmonary circulation of the llama at high and low altitudes. 
Thorax  1982;37(1):38-45.
We have studied the pulmonary circulation of three closely related animals, the llama, alpaca, and guanaco. The mean pulmonary arterial pressure of 12 llamas and one alpaca indigenous to high altitude in the Andes was found to be slightly but significantly higher than that of three llamas and three guanacos born and bred at low altitude in England. On the other hand, the medial thickness of the muscular pulmonary arteries and the relative weights of the two ventricles were the same in three llamas and one alpaca at high altitude as they were in one llama and two guanacos at low altitude. It is concluded that the pulmonary vasoconstrictive response to hypoxia, while present, is greatly reduced in this species and it is suggested that this may have taken place by evolutionary adaptation.
PMCID: PMC459242  PMID: 7071792
4.  The heart and pulmonary vasculature of the llama (Lama glama) 
Thorax  1974;29(4):463-471.
Heath, D., Smith, P., Williams, D., Harris, P., Arias-Stella, J., and Krüger, H. (1974).Thorax, 29, 463-471. The heart and pulmonary vasculature of the llama (Lama glama). A qualitative and quantitative histological study was made of the pulmonary trunk and muscular pulmonary arteries of a male and a pregnant female llama born and living at an altitude of 4,720 m above sea-level in the Peruvian Andes. A similar study was made on the fetal llama. The individual cardiac chambers of the two adults were weighed. Our results show that in the adult llama there is no hypertrophy of the right ventricle or of the media of the pulmonary trunk or small pulmonary arteries. This appears to be of evolutionary significance in respect of survival at high altitude and suggests that the llama does not have a sustained significant pulmonary hypertension. The pulmonary arteries of the fetal llama are thick-walled and we associate this with the physiological pulmonary hypertension of fetal life.
PMCID: PMC470181  PMID: 4854860

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