83 research outputs found
Detailed single crystal EPR lineshape measurements for the single molecule magnets Fe8Br and Mn12-ac
It is shown that our multi-high-frequency (40-200 GHz) resonant cavity
technique yields distortion-free high field EPR spectra for single crystal
samples of the uniaxial and biaxial spin S = 10 single molecule magnets (SMMs)
[Mn12O12(CH3COO)16(H2O)4].2CH3COOH.4H2O and [Fe8O2(OH)12(tacn)6]Br8.9H2O. The
observed lineshapes exhibit a pronounced dependence on temperature, magnetic
field, and the spin quantum numbers (Ms values) associated with the levels
involved in the transitions. Measurements at many frequencies allow us to
separate various contributions to the EPR linewidths, including significant
D-strain, g-strain and broadening due to the random dipolar fields of
neighboring molecules. We also identify asymmetry in some of the EPR lineshapes
for Fe8, and a previously unobserved fine structure to some of the EPR lines
for both the Fe8 and Mn12 systems. These findings prove relevant to the
mechanism of quantum tunneling of magnetization in these SMMs.Comment: Phys. Rev. B, accepted with minor revision
Characterization of the S = 9 excited state in Fe8Br8 by Electron Paramagnetic Resonance
High Frequency electron paramagnetic resonance has been used to observe the
magnetic dipole, M = 1, transitions in the excited
state of the single molecule magnet FeBr. A Boltzmann analysis of the
measured intensities locates it at 24 2 K above the ground
state, while the line positions yield its magnetic parameters D = -0.27 K, E =
0.05 K, and B = -1.3 10 K. D is thus smaller by 8%
and E larger by 7% than for . The anisotropy barrier for is
estimated as 22 K,which is 25% smaller than that for (29 K). These
data also help assign the spin exchange constants(J's) and thus provide a basis
for improved electronic structure calculations of FeBr.Comment: 7 pages, Figs included in text, submitted to PR
Setting up a multi-centric multiparametric hMRI protocol for the investigation of temporal lobe epilepsy
Prospective study of carmustine wafers in combination with 6-month metronomic temozolomide and radiation therapy in newly diagnosed glioblastoma: preliminary results
Object. Locoregional chemotherapy with carmustine wafers, positioned at surgery and followed by radiation therapy, has been shown to prolong survival in patients with newly diagnosed glioblastoma, as has concomitant radiochemotherapy with temozolomide. A combination of carmustine wafers with the Stupp treatment regimen has only been investigated in retrospective studies.
Methods. In a single-institution prospective study, the authors assessed 12-month progression-free survival (PFS), toxicity, and overall survival in patients with glioblastoma treated with surgery, carmustine wafers, radiotherapy, and 6-month metronomic temozolomide chemotherapy. Thirty-five patients with de novo glioblastoma, between the ages of 18 and 70 years, and with Karnofsky Performance Scale scores of at least 70, were included in the study. Patients were followed monthly and assessed using MRI every 2 months.
Results. After a median follow-up of 15 months, the median time to tumor progression was 12.5 months and median survival was 17.8 months. Due to toxicity (mostly hematological), 7 patients had to prematurely stop temozolomide treatment. Twenty-two patients developed Grade 3 CD4(+) lymphocytopenia. Three patients developed oral-esophageal candidiasis, 2 developed pneumonia, and 1 developed a dorsolumbar zoster. Early intracranial hypertension was observed in 1 patient, and 1 was treated empirically for suspected brain abscess. One patient died of Legionella pneumonia soon after repeat surgery.
Conclusions. Overall, this treatment schedule produced promising results in terms of PFS without a marked increase in toxicities as compared with the Stupp regimen. However, the gain in median survival using this schedule was less clear. Only prospective comparative trials will determine whether these preliminary results will translate into a long-term survival advantage with an acceptable toxicity profile
“LA CONSERVAZIONE DELLA CORTICALE ACETABOLARE NELLE PROTESI D’ANCA: INDICAZIONI AL COTILE ALLOCOR NON CEMENTATO, FOLLOW-UP A 9 ANNI”
Painful knee prosthesis: CT scan to assess patellar angle and implant malrotation
According to literature, the incidence of pain in knee prostheses is on the increase. In the last decade Authors have focused attention on rotational alignment of the prosthetic components. The aim of this study is to evaluate the efficiency of a new angle, which we define as patellar angle, in order to achieve early diagnosis of malrotation.
METHODS:
We set up a retrospective observational study recruiting 100 subjects who had undergone total knee prosthesis. 50 subjects suffered from knee anterior pain and 50 without any symptoms. Through CAT scan and VITREA software®, we were able to study the rotation of prosthetic components. We defined a new angle, which links the tibial component and the patella margins. The angles were measured by two different orthopaedic surgeons blinded to the study.
RESULTS:
The patella angle ranged from 10 to 28°, with an average value of 23.2° in the control group; in the study group the angle ranged from 26 to 34°, with an average value of 29.9°.
CONCLUSION:
Our data supported the reproducibility and efficacy of new angular value. It would represent a new method to detect tibial rotational malalignment
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