Magneto-structural correlations in oxalate-bridged Sr(ii)Cr(iii) coordination polymers: structure, magnetization, X-band, and high-field ESR studies.

The results of high-field electron spin resonance (HF-ESR) spectroscopy on the title 1D coordination polymers at frequencies up to 415 GHz, supported by X-ray diffraction, thermal, magnetic susceptibility, and X-band (10 GHz) ESR studies, are presented. The heterometallic compounds {SrCr2(phen)2(C2O4)4}·H2O (SrCrPhen) and {SrCr2(bpy)2(C2O4)4(H2O)}·5H2O (SrCrBpy) (phen = 1,10-phenanthroline, bpy = 2,2'-bipyridine) were synthesized. Structural analysis revealed double oxalate-bridged zigzag Sr-Cr chains while magnetic susceptibility studies showed paramagnetic behaviour of the complexes. HF-ESR spectroscopy data were analysed with a relevant spin-Hamiltonian, yielding the g, D and E parameters of the Cr(iii) ions. Both complexes showed small magnetic easy-axis type anisotropy with |D| ∼ 1 K; SrCrBpy has uniaxial anisotropy while SrCrPhen has biaxial anisotropy. HF-ESR studies have enabled us to establish rational magneto-structural correlations and revealed significant differences between very similar crystal structures. Additionally, the ability of SrCrPhen and SrCrBpy to be single-source precursors for the formation of Sr-Cr oxides was investigated.

Magnetic Excitations and Electronic Interactions in Sr_{2}CuTeO_{6}: A Spin-1/2 Square Lattice Heisenberg Antiferromagnet.

Sr_{2}CuTeO_{6} presents an opportunity for exploring low-dimensional magnetism on a square lattice of S=1/2 Cu^{2+} ions. We employ ab initio multireference configuration interaction calculations to unravel the Cu^{2+} electronic structure and to evaluate exchange interactions in Sr_{2}CuTeO_{6}. The latter results are validated by inelastic neutron scattering using linear spin-wave theory and series-expansion corrections for quantum effects to extract true coupling parameters. Using this methodology, which is quite general, we demonstrate that Sr_{2}CuTeO_{6} is an almost ideal realization of a nearest-neighbor Heisenberg antiferromagnet but with relatively weak coupling of 7.18(5) meV.

Strain-induced extrinsic high-temperature ferromagnetism in the Fe-doped hexagonal barium titanate.

Diluted magnetic semiconductors possessing intrinsic static magnetism at high temperatures represent a promising class of multifunctional materials with high application potential in spintronics and magneto-optics. In the hexagonal Fe-doped diluted magnetic oxide, 6H-BaTiO3-δ, room-temperature ferromagnetism has been previously reported. Ferromagnetism is broadly accepted as an intrinsic property of this material, despite its unusual dependence on doping concentration and processing conditions. However, the here reported combination of bulk magnetization and complementary in-depth local-probe electron spin resonance and muon spin relaxation measurements, challenges this conjecture. While a ferromagnetic transition occurs around 700 K, it does so only in additionally annealed samples and is accompanied by an extremely small average value of the ordered magnetic moment. Furthermore, several additional magnetic instabilities are detected at lower temperatures. These coincide with electronic instabilities of the Fe-doped 3C-BaTiO3-δ pseudocubic polymorph. Moreover, the distribution of iron dopants with frozen magnetic moments is found to be non-uniform. Our results demonstrate that the intricate static magnetism of the hexagonal phase is not intrinsic, but rather stems from sparse strain-induced pseudocubic regions. We point out the vital role of internal strain in establishing defect ferromagnetism in systems with competing structural phases.

[Results of strontium-yttrium-90 for pterygia]. / Résultat de la thérapie au strontium-yttrium-90 des ptérygions.

MATERIAL AND METHODS: [corrected] In the Institute of Radio-Oncology in Lucerne we reviewed the records of 75 patients with 97 pterygia in a retrospective study. All patients had the same number of fractions (4), the same single fraction dose (1250cGy) and the same total dose (5000cGy). The operation technique used was the bare sclera technique. Patients were treated following three different concepts. The first group was treated prior to the operation, 1 fraction weekly, at least 2 months before operation. The second group was treated postoperatively, also one fraction weekly, immediately after operation. The third group received 2 fractions prior to and 2 fractions following operation. RESULTS: We observed only 2 out of 97 (2%) recurrences in the second group. Because of their clinically inactive behavior these two cases required no further treatment. Three patients showed teleangiectasia as a moderate reaction. As a severe complication we observed one ulcus corneae, which was successfully treated with a lamellar keratoplasty, for a complication rate of 1%. CONCLUSION: Beta irradiation has proved to prevent pterygium recurrence. Severe late complications after excision and B-irradiation may partly be caused by other factors than irradiation alone. But it seems unequivocal that there is a relation with the high single-dose procedure of more than 2200cGy or re-irradiation. Fractionation must therefore be used.

[Dynamic thermoplastic cervico-thoracic orthoses in conservative and postoperative treatment of congenital torticollis]. / Dinamicna termoplasticna cervikotorakalna ortoza za konzervativno i postoperativno lecenje urodenog krivog vrata.

Contention of the corrected position of the rotation and anteflexion of the head and neck is very important for the congenital torticollis. Frequent reversion of the deformity was the consequence of the unproper passive and static cast bandages or rigid plastic and more functional leather-metal orthosis. Original dynamic cervico-thoracic orthosis, made of thermoplastic material, provides progressive, individual and stable correction and contetion of the best possible head and neck position. The value of the applied orthosis is proved by the excellent results in treatment of 12 non-operated children and 16 postoperative treated children that suffered of primary myogenic torticollis.

[Ultrasonic diagnosis of transitory synovitis of the hip joint in children]. / Ultrazvucna dijagnostika tranzitornog sinovita decijeg kuka.

The most common cause of a limp in childhood is transitory synovitis of the hip. At the Paediatric Surgery Clinic in Novi Sad, in the period from 1989 to 1991, 58 children were treated for hip transitory synovitis and the diagnosis was confirmed by ultrasonic finding of the exudate in the joint. The ultrasonic investigation of the hips was performed by using Siemens and Kretz scanners equipped with 5 MHz linear or sector transducers. The approach to the hip was frontal and the lower extremity has been in the neutral position. The distance between the femoral neck and the joint capsule was verified according to the Adam's morphometric procedure. The measured pathological values were from 7 mm to 14 mm (normal values are from 2 mm to 4 mm). In the routine transitory synovitis diagnosis, real-time arthrosonography of the hip shows high sensitivity, accuracy and selective values compared to other diagnostic procedures.

[Prevention, care and screening of hips of newborn infants]. / Prévention, soins et surveillance des hanches de bébés.

The frequency of C.D.H. and the indications for surgical treatment have been considerably reduced. Since a 3-part prevention protocol has been initiated: screening of newborns, prophylactic triple-diapering in slight flexion-abduction, aided by the availability of the equipment, and repeated examinations of infants.

Triple prevention of congenital dislocation of the hip.

Triple prevention of congenital dislocation of the hip consists of (a) examining newborns so as to apply treatment as early as possible in symptomatic and suspected cases, (b) regular diapering in abduction of all presumably healthy hips by means of soft abduction pants so as to direct possible cases of dysplasia toward normal development, and (c) reexamination of these hips until the child can walk so as to discover missed cases. Primary treatment of diagnosed and suspected hip dislocations consists of immediate application of a Frejka splint and abduction exercises, followed by a radiograph at the age of 4 months. Persistence of any clinical symptom for 3 weeks requires intensification of treatment by use of the Pavlik harness.