Mossbauer and magnetization studies of amorphous NdFeB compositionally modulated thin films

Several NdFeB compositionally modulated thin films are studied by using both conversion electron Mossbauer spectra and SQUID (superconducting quantum-interference-device) magnetometry. Both the hyperfine fields and the easy magnetization magnitude are not correlated with the modulation characteristic length (lambda) while the magnetization perpendicular to the thin-film plane decreases as lambda increases. The spectra were recorded at room temperature being the gamma rays perpendicular to the substrate plane. The magnetization measurements were recorded by using a SHE SQUID magnetometer in applied magnetic fields up to 5.5 T and in the temperature range between 1.8 and 30 K

Bone turnover markers in HIV-infected patients before starting antiretroviral therapy

Purpose: Bone turnover markers (BTM) - aminoterminal propeptide of type 1 collagen (P1NP) and C-terminal telopeptide of type 1 collagen (β-CTX) - are related to bone density and fracture risk. A high prevalence of osteopenia/osteoporosis and hypovitaminosis D has been reported in HIV patients, however there are few data about BTM in this population. Our aim was to analyse the prevalence of elevated serum levels of BTM in HIV patients before starting antiretroviral therapy (ART), and related factors. Methods: Cross-sectional study of a series of HIV-patients who started ART during June/11–June/12 in our hospital. Patients with presence of diseases or treatments known to affect bone metabolism were excluded. Epidemiological, clinical, and immunovirological data in addition to serum fasting levels of glucose, lipid profile, calcium, phosphate, alkaline phosphatase, 25-hydroxyvitamin D3 (25OHD), parathyroid hormone (PTH), P1NP, and β-CTX were collected. Definitions: hypovitaminosis D if 25OHD<30 ng/ml, vitamin D deficiency if 25OHD<20 ng/ml; elevated levels of BTM if β-CTX (ng/ml) >0.64 (men<70 years),>0.85 (men >70 years),>0.58 (pre-menopause women), >0.99 (post-menopause women), or P1NP (ng/mL)>69.4 (men <60 years), >71.1 (men>60 years), >55.7 (pre-menopause women), >61.2 (post-menopause women). Results: 47 patients were included, 91.5% men, median age 37.1 years (30.0–44.3), and 93.6% sexual transmission of HIV (34 HMX, 10 HTX). Median time since the diagnosis of HIV was 3.4 months (1.4–31.7); there were 7 (14.9%) Aids cases, median CD4 count was 277/mm3 (155–433), and HIV-VL 4.8 log10 (4.1–5.2). Median serum 25OHD was 29 µg/L (21.9–41.1), with a prevalence of hypovitaminosis of 52.2%, and deficiency of 17.4%. PTH was in range in all cases. Median serum P1NP was 33.3 ng/mL (24.5–52.5) and β-CTX 0.25 ng/mL (0.20–0.45); five (11.4%) patients presented high levels of BTM: 4 men, median age 37.1 years, median CD4 count 247/mm3, median HIV-VL 5.18 log10, and one with hypovitaminosis D. Elevated BTM were related with no clinical, analytical, immunovirological parameters nor with serum levels of 25OHD nor PTH. Conclusions: The prevalence of elevated BTM was high in this series of HIV-patients, mostly young men, with short time of HIV infection and with no immunovirologic control. BTM were related with no clinical nor analytical data

Primary pleural myxoid liposarcoma: case report and literature review

Myxoid liposarcoma is a histological subtype of malignant tumors within the group of sarcomas. It is more common in men between the ages of 40 and 50 years. Diagnosis is difficult because they are usually asymptomatic lesions, computed tomography (CT) scan and magnetic resonance are the studies of choice. The gold of treatment is surgical resection with free margins. Chemotherapy and radiotherapy have shown a good response. A 46-year-old male was detected incidental mediastinal lesion by radiography, CT scan showed a hypodense lesion in the right hemithorax that extended to the left hemithorax, infiltrating the diaphragm and large vessels. The patient underwent an exploratory thoracotomy, finding a multilobulated tumor and mucous content approximately 600 ml, adjacent structures were infiltrated, so complete resection was not possible. Subsequently, adjuvant chemotherapy given. The histopathological diagnosis was myxoid liposarcoma. Myxoid liposarcoma is a malignant lesion. The primary pleural origin is rare. Surgical resection with free margins has a good prognosis. Due to advanced disease, a complete resection in this case was not possible, that compromised the patient prognosis

Nonlinear response of single-molecule nanomagnets: equilibrium and dynamical

We present an experimental study of the {\em nonlinear} susceptibility of Mn$_{12}$ single-molecule magnets. We investigate both their thermal-equilibrium and dynamical nonlinear responses. The equilibrium results show the sensitivity of the nonlinear susceptibility to the magnetic anisotropy, which is nearly absent in the linear response for axes distributed at random. The nonlinear dynamic response of Mn$_{12}$ was recently found to be very large and displaying peaks reversed with respect to classical superparamagnets [F. Luis {\em et al.}, Phys. Rev. Lett. {\bf 92}, 107201 (2004)]. Here we corroborate the proposed explanation -- strong field dependence of the relaxation rate due to the detuning of tunnel energy levels. This is done by studying the orientational dependence of the nonlinear susceptibility, which permits to isolate the quantum detuning contribution. Besides, from the analysis of the longitudinal and transverse contributions we estimate a bound for the decoherence time due to the coupling to the phonon bath.Comment: 13 pages, 8 figures, resubmitted to Phys. Rev. B with minor change

Large quantum nonlinear dynamic susceptibility of single-molecule magnets

The nonlinear dynamical response of Mn$_{12}$ single-molecule magnets is experimentally found to be very large, quite insensitive to the spin-lattice coupling constant, and displaying peaks reversed with respect to classical superparamagnets. It is shown that these features are caused by the strong field dependence of the relaxation rate due to the detuning of energy levels between which tunneling takes place. The nonlinear susceptibility technique, previously overlooked, is thus proposed as a privileged probe to ascertain the occurrence of quantum effects in mesoscopic magnetic systems.Comment: 4 pages, 4 figure

Piezochromic properties of a D-A-D platform: A joint experimental and theoretical perspective

Organic π-conjugated molecules with mechanochromic luminescence properties have attracted great interest in the last two decades due to their numerous applications in the optoelectronic field, such as sensors, probes and security inks. Materials that modify their colour under pressure are known as piezochromic materials. Usually, this variation is provoked by changes in the molecular structure, for example, crystal-to-amorphous phase transitions, modifications in dihedral angles or bond distances, and intermolecular interactions. The molecule proposed in this study is a TADF (Thermally activated delayed fluorescence) U-shaped molecule composed by two donors and one acceptor (D-A-D) units with a π-conjugated skeleton [1]. It was synthetized as a powder which under different crystallization methods gives rise to different conformers varying the dihedral angle of the bond that links the D and A units. The donors are two phenothiazine units and the acceptor is a dibenzo[a,j]phenazine unit located in the central core. Two different conformers have been analysed: the quasi equatorial - quasi equatorial (denoted as 1R) and the quasi axial - quasi axial (denoted as 1Y). In this project, we study the configurational changes triggering the piezochromic effects combining density functional theory (DFT) calculations with Raman spectroscopy experiments of the 1R and 1Y conformers during heating or in compression via a sapphire anvil cell [2]. Both show pressure and temperature dependence properties. Besides, these changes are reversible meaning that when the stimuli stop they revert to its original conformation. When these molecules are exposed to different ambient (like pressure or temperature variations) they evolved to a third conformer with an intermediate dihedral angle that results in different Raman, emission and absorption behaviour.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Temporal Evolution of the Magmatic System at Tungurahua Volcano, Ecuador, detected by geodetic observations

Changes in the pathway and timescale of magma ascent can be responsible for variations in eruptive style during long-lived eruptions, but are only documented at a small number of well-instrumented systems. Here we integrate PS-InSAR from high resolution TerraSAR-X radar imagery with continuous GPS data from 4 sites at Tungurahua volcano, Ecuador. Our results show long-term uplift between 2011-2014 associated with a continuously in ating prolate reservoir at a depth of 10 km beneath the summit. Comparisons with eruptive flux, taking compressibility into account, suggest that during this time period slightly over half the magma supplied to the system was erupted. The observations span three distinct phases of eruption and in 2012-2013, an increase in eruptive activity was accompanied by uplift on the volcano's western flank. Similar episodes have previously been observed during large Vulcanian eruptions and we attribute them to intrusions into an area of mechanical weakness. A localised patch of subsidence mid-way up the Tungurahua's western flank is co-located with a swarm of shallow long-period seismicity and may represent a potential site for a development of a lateral vent. This study demonstrates that satellite geodetic techniques are capable of characterising the geodetic signature of transitions in eruptive style during long-lived andesitic eruptions although the deformation is cm-scale of steep volcanic edi fices.NERC Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonic

Revealing hidden clonal complexity in Mycobacterium tuberculosis infection by qualitative and quantitative improvement of sampling

AbstractThe analysis of microevolution events, its functional relevance and impact on molecular epidemiology strategies, constitutes one of the most challenging aspects of the study of clonal complexity in infection by Mycobacterium tuberculosis. In this study, we retrospectively evaluated whether two improved sampling schemes could provide access to the clonal complexity that is undetected by the current standards (analysis of one isolate from one sputum). We evaluated in 48 patients the analysis by mycobacterial interspersed repetitive unit–variable number tandem repeat of M. tuberculosis isolates cultured from bronchial aspirate (BAS) or bronchoalveolar lavage (BAL) and, in another 16 cases, the analysis of a higher number of isolates from independent sputum samples. Analysis of the isolates from BAS/BAL specimens revealed clonal complexity in a very high proportion of cases (5/48); in most of these cases, complexity was not detected when the isolates from sputum samples were analysed. Systematic analysis of isolates from multiple sputum samples also improved the detection of clonal complexity. We found coexisting clonal variants in two of 16 cases that would have gone undetected in the analysis of the isolate from a single sputum specimen. Our results suggest that analysis of isolates from BAS/BAL specimens is highly efficient for recording the true clonal composition of M. tuberculosis in the lungs. When these samples are not available, we recommend increasing the number of isolates from independent sputum specimens, because they might not harbour the same pool of bacteria. Our data suggest that the degree of clonal complexity in tuberculosis has been underestimated because of the deficiencies inherent in a simplified procedure

SLOANEA SUBGÉNERO QUADRISEPALA (ELAEOCARPACEAE) EN BOLIVIA

Se presenta una sinopsis del subgénero Quadrisepala del género Sloanea, para Bolivia, en la que reconocen once especies (Sloanea fendleriana, S. garckeana, S. gentryi, S. grandis, S. latifolia, S. laxiflora, S. porphyrocarpa, S. rojasiae, S. subsessilis, S. terniflora y S. uniflora), destacando que S. latifolia, S. porphyrocarpa y S. rojasiae son nuevos registros para la flora de Bolivia. Adicionalmente, se complementa la descripción original de S. subsessilis con la incorporación de caracteres del fruto y se proponen lectotipos para S. grandis y S. porphyrocarpa