Tuning the magnetic anisotropy energy by external electric fields of CoPt dimers deposited on graphene.

In the framework of first-principles calculations, we comprehensively investigate the external electric-field (EF) manipulation of the magnetic anisotropy energy (MAE) of alloyed CoPt dimers deposited on graphene. In particular, we focus on the possibility of tuning the MAE barriers under the action of external EFs and on the effects of Co-substitution. Among the various considered structures, the lowest-energy configurations were the hollow-upright and top-upright, having the Co-atom closest to the graphene layer. The optimal and higher energy configurations were related to the electronic structure through the local density of states and hybridizations between the transition-metal (TM) atoms of the dimer and graphene. In contrast to Co2/graphene [M. Tanveer, J. Dorantes-Dávila and G. M. Pastor, Phys. Rev. B, 2017, 96(22), 224413.], the CoPt dimer having the hollow-upright ground-state configuration, exhibits a much lower value of the MAE (about |ΔE| ≃ 4.5 meV per atom) and the direction of the magnetization lies in the graphene layer. Moreover, we observe a spin-reorientation transition occurring at εz ≃ 0.5 V Å-1, which opens the possibility of inducing magnetization switching by external electric fields. The microscopic origin of the changes of the MAE associated with changes in the EF has been qualitatively related to the details of the electronic structure by analyzing the local density of states and to the spin-dependent electronic densities close to the Fermi energy. Finally, the role of local environment was quantified by performing electronic structure and magnetic calculations on several higher-energy structure configurations.

Effects of DC Magnetic Fields on Magnetoliposomes.

The potential use of magnetic nanoparticles (MNPs) in biomedicine as magnetic resonance, drug delivery, imagenology, hyperthermia, biosensors, and biological separation has been studied in different laboratories. One of the challenges on MNP elaboration for biological applications is the size, biocompatibility, heat efficiency, stabilization in physiological conditions, and surface coating. Magnetoliposome (ML), a lipid bilayer of phospholipids encapsulating MNPs, is a system used to reduce toxicity. Encapsulated MNPs can be used as a potential drug and a gene delivery system, and in the presence of magnetic fields, MLs can be accumulated in a target tissue by a strong gradient magnetic field. Here, we present a study of the effects of DC magnetic fields on encapsulated MNPs inside liposomes. Despite their widespread applications in biotechnology and environmental, biomedical, and materials science, the effects of magnetic fields on MLs are unclear. We use a modified coprecipitation method to synthesize superparamagnetic nanoparticles (SNPs) in aqueous solutions. The SNPs are encapsulated inside phospholipid liposomes to study the interaction between phospholipids and SNPs. Material characterization of SNPs reveals round-shaped nanoparticles with an average size of 12 nm, mainly magnetite. MLs were prepared by the rehydration method. After formation, we found two types of MLs: one type is tense with SNPs encapsulated and the other is a floppy vesicle that does not show the presence of SNPs. To study the response of MLs to an applied DC magnetic field, we used a homemade chamber. Digitalized images show encapsulated SNPs assembled in chain formation when a DC magnetic field is applied. When the magnetic field is switched off, it completely disperses SNPs. Floppy MLs deform along the direction of the external applied magnetic field. Solving the relevant magnetostatic equations, we present a theoretical model to explain the ML deformations by analyzing the forces exerted by the magnetic field over the surface of the spheroidal liposome. Tangential magnetic forces acting on the ML surface result in a press force deforming MLs. The type of deformations will depend on the magnetic properties of the mediums inside and outside the MLs. The model predicts a coexistence region of oblate-prolate deformation in the zone where χ = 1. We can understand the chain formation in terms of a dipole-dipole interaction of SNP.

[Reversible cerebral vasoconstriction syndrome secondary to secreting jugular paraganglioma]. / Sindrome de vasoconstriccion cerebral reversible secundario a un paraganglioma yugular secretor de metanefrinas.

TITLE: Sindrome de vasoconstriccion cerebral reversible secundario a un paraganglioma yugular secretor de metanefrinas.

Prevalencia de fibrilación auricular paroxística en registros de holter de 24 horas realizados en Clínica Universitaria Reina Fabiola / Prevalence of paroxysmal atrial fibrillation in Holter records of 24 hours performed in Clínica Universitaria Reina Fabiola

INTRODUCCIÓN: La fibrilación Auricular Paroxística (FAP) es el tema central de este trabajo; su estudio es importante porque aumenta los riesgos de complicaciones tromboembolicas cerebrales, siendo estas las principales causas de mortalidad y morbilidad. OBJETIVOS: El objetivo principal del siguiente trabajo es evaluar la prevalencia de fibrilación auricular paroxística (FAP) en registros de Holter 24 hs y su relación con distintos factores de riesgo. EL objetivo secundario fue evaluar la relación de la FAP y sus complicaciones tromboembólicas cerebrales relacionándolas con diferentes variables. Material y Métodos: Fueron revisados 960 Holter 24 hs consecutivos realizados desde enero del 2014 hasta diciembre del 2015 entre los que se identificaron 39 pacientes con FAP. Se analizaron los antecedentes patológicos y presencia de complicaciones tromboembólicas cerebrales. Los datos se consignaron en una ficha diseñada para tal fin y los resultados se expresaron con la media ± DS para las variables cuantitativas y porcentajes para variables cuantitativas. Se consignó un valor de p <0,05 para determinar significación estadística. Se utilizó el test estadístico CHI 2. RESULTADOS: La cantidad de pacientes con FAP fueron 39 (4%) del total de estudios revisados, la edad promedio de los pacientes fue 67,92 (35-92) años, siendo la mayoría del sexo masculino 26 (67%). Las patologías de base fueron HTA 32 (82%); DLP 25 (64%); enfermedad vascular (EV) 15 (38%); DBT 14 (36%); IC 12 (31%); tabaquismo 8 (21%); 8 (21%) eran obesos y valvulopatía 3 (8%). De los pacientes con FAP, 11 (28%) sufrieron eventos tromboembólicos cerebrales; de ellos6 (55%) eran de sexo masculino. Nueve (82 %) padecieron ACV y 2 (18%) CIT. Las variables asociadas a eventos tromboembólicos cerebrales fueron la edad mayor a 75 años (p 0.009) y el antecedente de EV (p 0.01). CONCLUSIONES: En este estudio la prevalencia de FAP en Registro de Holter de 24 hs fue del 4 %, más frecuente en el sexo masculino y con patología de base predominante la HTA%. Se observó una alta prevalencia de eventos tromboembólicos cerebrales en pacientes con FAP que se relacionó significativamente con la edad mayor a 75 años y la presencia de EV. (AU)

INTRODUCTION: The main target of the following work is to evaluate the AF predominance in records of 24hs Holter and its relation with different risk factors. The secondary target was to evaluate the relation betwen AF and brain tromboembolics complication relating them to different variables. MATERIAL AND METHODS: 960 consecutive studies were checked realized from January, 2014 until December, 2015. 39 patients were included with AF, its case histories were checked seeing its pathological precedents and if they presented brain tromboembolics complication. The information was recorded in a card designed for such an end and the results SD expressed himself with the average ± for the quantitative variables and percentages presented in the shape of graphs or stage as it should correspond. As statistical tool used the program SPSS v11. 0Sp. A value was recorded of p <0.05 to determine statistical significance in case of comparison between groups. RESULTS: The patients' quantity with AF there were 39 that correspond to 4 % of the checked studies, the age average of the patients was 67,92 years (35-92 years) being most of the masculine sex 26 (67 %). The base pathologies were a HBP 32 (82 %); Dyslip 25 (64 %); VD 15 (38 %); DM 14 (36 %); HF 12 (31%); Tabaquic 8 (21 %); 8 (21 %) was obese and only 3 (8 %) Valvulopathies. Of the patients with AF, 11 (28 %) suffered brain tromboembolics events and 28 (72 %) was not affected; of those who had brain tromboembolic events it was of masculine sex 6 (55 %) and feminine 5 (45 %) in turn 9 (82 %) endured BTE and 2 (18 %) TCI and the variables that marked a difference as per statistics significant as for brain tromboembolic events were the age oldest than 75 years (p 0.009) and the precedent of Vascular Illness (p 0. 01) CONCLUSIONS: High AF predominance in Record of Holter of 24 hs was 4 % more frequent in the masculine sex a 67 % and that the pathology of predominant base was the hypertension in 82 %. High predominance of 28 % of Brain tromboembolic events in patients with AF and that was related significantly to the age biggest than 75 years and the presence of Vascular Illness. (AU)

Electron pair emission from a W(001) surface: photon versus electron excitation.

The electron pair emission from a W(001) surface was studied using a coincidence time-of-flight spectrometer. The aim of this study was to compare the pair emission upon electron impact and upon photon absorption. The energy distributions are markedly different for these two experiments. From this we conclude that the photon-stimulated pair emission carries a significant contribution from a double photoemission process, while the process of first creating a photoelectron, which in a subsequent collision leads to pair emission, is of less importance.

Magnetic properties of Co(N)RhM nanoparticles: experiment and theory?

The magnetism of Co-Rh nanoparticles is investigated experimentally and theoretically. The particles (approximately 2 nm) have been synthesized by decomposition of organometallic precursors in mild conditions of pressure and temperature, under hydrogen atmosphere and in the presence of a polymer matrix. The magnetic properties are determined by SQUID, Mössbauer spectroscopy, and X-ray magnetic circular dichroism (XMCD). The structural and chemical properties are characterized by wide angle X-ray scattering, transmission electronic microscopy and X-ray absorption near edge spectroscopy. All the studied Co-Rh clusters are magnetic with an average spin moment per atom mu that is larger than the one of macroscopic crystals or alloys with similar concentrations. The experimental results and comparison with theory suggest that the most likely chemical arrangement is a Rh core, with a Co-rich outer shell showing significant Co-Rh mixing at the interface. Measured and calculated magnetic anisotropy energies (MAEs) are found to be higher than in pure Co clusters. Moreover, one observes that the MAEs can be tuned to some extent by varying the Rh concentration. These trends are well accounted for by theory, which in addition reveals important spin and orbital moments induced at the Rh atoms as well as significant orbital moments at the Co atoms. These play a central role in the interpretation of experimental data as a function of Co-Rh content. A more detailed analysis from a local perspective shows that the orbital and spin moments at the Co-Rh interface are largely responsible for the enhancement of the magnetic moments and magnetic anisotropy.

Estudio comparativo de las técnicas de obturación termoplástica Trifecta y Ultrafil: tiempo de obturación y extrusión apical / A comparison of two thermoplastic obturation techniques: trifecta and ultrafil. Time of obturation and apical extrusion

El sistema de obturación termoplástica Ultrafil es más sencillo y rápido que la técnica de condensación lateral, pero con mayor extrusión apical. A su vez, la técnica Trifecta, considerada más engorrosa, también presenta mayor extrusión que la condensación lateral, pero con menor microfiltración apical. Objetivo: El objetivo de este estudio fue comparar in Vitro los sistemas Trifecta y Ultrafil en relación a la extrusión apical y tiempo de trabajo. Material y método: Cuarenta conductos mesiovestibulares de molares extraídos fueron instrumentados mecánicamente (HERO 642); luego divididos aleatoriamente en 2 grupos: Grupo 1 obturado con Trifecta y grupo 2 con Ultrafil. En ambos se usó sellador TopSeal. Los conductos fueron evaluados, bajo un microscopio de luz 40x, para determinar la extrusión de material de obturación. Resultados y conclusiones: La extrusión en el grupo Ultrafil fue significativamente mayor que en el grupo obturado con Trifecta. El tiempo de obturación fue significativamente menor en la técnica Ultrafil (p<0,05 Chi cuadrado)

The thermoplasticized gutta-percha system Ultrafil is easier and quicker than the lateral condensation technique, but a bigger index of apical extrusion. Trifecta system has the same problem: It is a difficult technique and presents more incidence of apical extrusion than the lateral condensation technique, but it shows a lower apical microleakage. Objective: The aim of this study was to compare in Vitro Trifecta and Ultrafil systems regarding to apical extrusion and working time. Material and methodology: 40 bucco-mesial canals of extracted human molars were prepared mechanically (HERO 642) and randomly divided into two groups: Group 1 was obturated with Trifecta system and group 2 with Ultrafil system. Topseal was used in both groups as a sealer. The canals were observed with a light microscope (40x) and apical extrusion was recorded. Results and Conclusion: The Ultrafil group resulted in significantly more extrusion than Trifecta group. The average time of obturation was significantly smaller in the Ultrafil technique (p<0,05 Chi Square)

Malaria: burden of disease.

Despite more than 100 years since Laveran described plasmodium species and Ross confirmed that they were transmitted by female anopheline mosquitoes, malaria remains a leading cause of morbidity and mortality worldwide. Although the areas where transmission takes place have reduced, and they are by now confined to the inter tropical areas, the number of people living at risk has grown to about 3 billion, and is expected to go on increasing. Not only does malaria cause around 500 million cases every year, and between 1 and 3 million deaths, but it also carries a huge burden that impairs the economic and social development of large parts of the planet. The failed attempt to eradicate malaria gave way to the control policy that was followed by a huge resurgence of malaria during the late 70s and 80s. Together with the emergence and spread of resistance to chloroquine and the weak health infrastructure in many of the endemic countries, particularly in Africa, the malaria situation worsened worldwide. The last decade of the 20th century was witness to the international community becoming increasingly aware of the unacceptable situation that the burden of malaria represented to large parts of the world. Renewed efforts to describe the problem, design and evaluate new control strategies, design and develop new drugs, better understand the biology of the parasite and the immunity it induces in the human host, develop candidate vaccines, together with new financial support constitute renewed hope that may lead to new trends in global health.

Analysis of the mechanisms of resistance to several antimicrobial agents in Shigella spp. causing travellers' diarrhoea.

Eighty isolates of Shigella spp. (37 Shigella flexneri and 43 Shigella sonnei) from patients with travellers' diarrhoea were studied. Susceptibility tests revealed high levels of resistance, especially to ampicillin (65%), tetracycline (78%) and trimethoprim (75%), and particularly among the S. flexneri isolates. Dihydrofolate reductase 1 genes (dfrA1) were prevalent among the trimethoprim-resistant isolates, while oxa genes predominated among the ampicillin-resistant isolates. Chloramphenicol resistance was associated with production of chloramphenicol acetyltransferase, while nalidixic acid-resistant isolates had a single mutation in the gyrA gene. The results indicate a continuing need for resistance surveillance and rational use of antimicrobial agents.

Genetic diversity of Shigella species from different intercontinental sources.

One hundred and twenty three strains of Shigella spp. (mostly Shigella sonnei and Shigella flexneri) were isolated between 1995 and 2000 from patients suffering from traveller's diarrhoea. Seventy nine of them have been typed by digestion of their chromosomal DNA with Xba I and pulsed field gel electrophoresis. Results show a high degree of heterogeneity in both S. sonnei and S. flexneri isolates. This is the first time that the molecular typing of such a high number of geographically unrelated isolates of Shigella sp. is carried out, showing a high level of genomic re-arrangement.

[Primary peritonitis in previously healthy children]. / Peritonitis primaria en niños sanos.

INTRODUCTION: Primary peritonitis occurs rarely in childhood, affecting mainly children with nephrosis or liver disease and only rarely occurring in previously healthy children. The aim of this case report is to describe the clinical features and natural course of primary peritonitis in six previously healthy children and to review the literature on the topic. MATERIAL AND METHOD: The clinical features and course of primary peritonitis in six previously healthy children are described. The diagnosis was made at laparotomy, which showed no intraabdominal findings, such as intestinal perforation. RESULTS: Presentation was acute and all the patients presented within 24 h of onset of symptoms. The most common presenting features were fever (100 %) and abdominal pain (100 %). Leucocytosis (> 15,000/mm3) was observed in four patients (66 %). Microorganisms were isolated from peritoneal fluid in four patients (Escherichia coli in two, Streptococcus pneumoniae in one and Gram-negative bacteria in one). Recovery was rapid and no postoperative complications were observed. CONCLUSION: Primary peritonitis in patients without underlying causes is clinically indistinguishable from acute appendicitis and diagnosis is usually made at surgery. The hallmarks of therapy are antibiotics and prompt exploratory laparotomy with appendectomy and the prognosis is good.

Detección de patologías no diagnosticadas en pacientes internados / Detection of undiagnosed conditions in hospitalized patients

Introducción : Un niño hospitalizado representa una oportunidad, en algunos casos la primera o incluso la única, de recibir una completa evaluación médica que optimice su potencial de desarrollo humano, y el pediatra debe estar conciente de ello y comprometido con su tarea. Objetivo : Evaluar la utilidad del examen físico completo y el interrogatorio dirigido en niños internados para la detección de patologías no detectadas anteriormente y que pueden tener importancia en su vida y cuidados. Material y Método : Se estudiaron niños ingresados al CIM 63 durante el año 2002.Estudio descriptivo, transversal y prospectivo. El examen físico consistió en la valoración semiológica sistemática. No se tuvieron en cuenta los cambios clínicos que ocurrieron como parte de la evolución natural de la enfermedad que motivó la internación. No se incluyeron las inmunizaciones incompletas, la anemia, ni los aspectos psicosociales, trastornos escolares y del lenguaje. Resultados : encontramos patologías no diagnosticadas en 12 de 3.485 pacientes egresados (3.4/1000). Los hallazgos fueron : 2 escoliosis, 1 neurofibromatosis, 1 osteogénesis imperfecta, 1 cardiopatía, 1 púrpura trombocitopénica crónica, 2 afecciones urinarias, 3 afecciones neurológicas, 1 ambliopía, y en 3 niños se detectaron malformaciones menores. Sólo 3 pacientes (25 por ciento) tenían pediatra de cabecera. Un enfoque clínico integral y examenes complementarios mínimos permitió efectuar diagnósticos como osteogénesis imperfecta, escoliosis, cardiopatías, uropatías, siringomielia, púrpura, etc que son importantes ya que muchos de estos cuadros son invalidantes o incapacitantes si no son controlados a tiempo

Detección de patologías no diagnosticadas en pacientes internados / Detection of undiagnosed conditions in hospitalized patients

Introducción : Un niño hospitalizado representa una oportunidad, en algunos casos la primera o incluso la única, de recibir una completa evaluación médica que optimice su potencial de desarrollo humano, y el pediatra debe estar conciente de ello y comprometido con su tarea. Objetivo : Evaluar la utilidad del examen físico completo y el interrogatorio dirigido en niños internados para la detección de patologías no detectadas anteriormente y que pueden tener importancia en su vida y cuidados. Material y Método : Se estudiaron niños ingresados al CIM 63 durante el año 2002.Estudio descriptivo, transversal y prospectivo. El examen físico consistió en la valoración semiológica sistemática. No se tuvieron en cuenta los cambios clínicos que ocurrieron como parte de la evolución natural de la enfermedad que motivó la internación. No se incluyeron las inmunizaciones incompletas, la anemia, ni los aspectos psicosociales, trastornos escolares y del lenguaje. Resultados : encontramos patologías no diagnosticadas en 12 de 3.485 pacientes egresados (3.4/1000). Los hallazgos fueron : 2 escoliosis, 1 neurofibromatosis, 1 osteogénesis imperfecta, 1 cardiopatía, 1 púrpura trombocitopénica crónica, 2 afecciones urinarias, 3 afecciones neurológicas, 1 ambliopía, y en 3 niños se detectaron malformaciones menores. Sólo 3 pacientes (25 por ciento) tenían pediatra de cabecera. Un enfoque clínico integral y examenes complementarios mínimos permitió efectuar diagnósticos como osteogénesis imperfecta, escoliosis, cardiopatías, uropatías, siringomielia, púrpura, etc que son importantes ya que muchos de estos cuadros son invalidantes o incapacitantes si no son controlados a tiempo

Molecular characterization of the integrons in Shigella strains isolated from patients with traveler's diarrhea.

The prevalence and characterization of Class 1 integrons has been performed in eighty three strains of Shigella spp., isolated between 1995 and 2000 from patients with traveler's diarrhea. A low prevalence (13.25%) was recorded. Nine different integrons were found among 11 multiresistant strains, with a total of 10 different gene cassettes encoding for resistance to trimethoprim (dfrA1, dfrA5, dfrA7, dfrA12, and dfrA15), aminoglycosides (aadA1a and aadA2), beta-lactam antibiotics (oxa2) or ORF with unknown function (orfD and orfF). A high prevalence of dfr and aad gene cassettes was observed. The low incidence of Class 1 integrons observed in this study is in contrast with the known facility that the Shigella genus has to gain and transfer plasmids.

Integron-mediated antibiotic multiresistance in Acinetobacter baumannii clinical isolates from Spain.

OBJECTIVE: To determine whether non-epidemiologically related, antibiotic-resistant isolates of Acinetobacter baumannii from different geographical origins possess common type 1 integrons. METHODS: The epidemiologic relationships between seven A. baumannii strains recovered from different Spanish hospitals were established by pulsed-field gel electrophoresis, the presence of integrons being determined by PCR and DNA sequencing. RESULTS: Integron analysis showed the presence of four different integrons, containing six different known genes (aacC1, aacA4, aadA1, aadB, oxa21 and oxa37) plus an ORF. It was found that the same integron was present in different unrelated strains and that related strains could have different integrons. CONCLUSION: These results show the potential risk of integron dissemination among different strains of A. baumannii.

A comparison of apical sealing and extrusion between Thermafil and lateral condensation techniques.

Forty curved canals from 20 mesial roots of extracted human mandibular molars were instrumented (Profile .04) using a crown-down technique and divided into two groups. The experimental group was obturated using the Thermafil technique and the control group was obturated using the lateral condensation technique. Topseal sealer was used in both groups. Apical extrusion was recorded. Two molars were used as control teeth. All specimens were stored in 100% humidity for 1 wk, coated with nail polish, except for the apical 2 mm, and were suspended in black India ink for 48 h. Molars were decalcified, rendered transparent, and linear dye penetration was measured. Linear dye leakage and apical extrusion between the techniques were not statistically different (Mann-Whitney U test).