Production of graphene nanoplate/polyetheretherketone composites by semi-industrial melt-compounding.

Current studies on nanocomposites have focused on their multifunctional properties and their industrial production. In this work, polyetheretherketone (PEEK)/graphene nanoplate (GNP) composites were produced by a direct semi-industrial process. Different percentages of untreated GNP (1, 5, and 10 wt.%) were added to PEEK by employing melt-compounding followed by injection-moulding. Despite the semi-industrial approach used, the modulus, strength, and Poisson coefficient of the nanocomposites (1 and 5 wt.%) were not significantly affected by the addition of GNP. However, there was a slight decrease in the strength at 10 wt.% GNP. Our study also shows that the thermal conductivities of PEEK/GNP composites are up to 2.5 times higher than that of pure PEEK.

Impacto de la estimulación subtalámica a largo plazo sobre la situación cognitiva de los pacientes con enfermedad de Parkinson avanzada / Long-term impact of subthalamic stimulation on cognitive function in patients with advanced Parkinson's disease

OBJETIVO: El objetivo es evaluar los efectos de la estimulación cerebral profunda del núcleo subtalámico bilateral (STN-DBS) sobre el estado cognitivo de los pacientes con enfermedad de Parkinson 5 años después de la cirugía. Materiales y métodos: En este estudio prospectivo se incluyeron 50 pacientes con enfermedad de Parkinson (62,5% hombres, edad media 62,2 ± 8,2 años y duración de la enfermedad 14,1 ± 6,3 años) sometidos a STN-DBS. Todos los pacientes fueron evaluados preoperatoriamente y un año después de la cirugía, y 40 pacientes fueron seguidos hasta 5 años. En cada visita se realizaron las siguientes evaluaciones neuropsicológicas: Mini-Mental State Examination, Mattis Dementia Rating Scale (MDRS), test de secuencias números-letras de WAIS III-LN, Prueba de dibujo de reloj, Prueba de aprendizaje verbal auditivo Rey, la Prueba de retención visual de Benton, la Prueba de juicio de orientación de línea de Benton, la fluidez verbal fonética y semántica, la Prueba Stroop y la Escala de clasificación de depresión de Montgomery-Asberg. RESULTADOS: Anualmente se observaron reducciones en la puntación de Mini-Mental State Examination (-0,89%), Prueba del dibujo de reloj (-2,61%) y MDRS (-1,72%), fueron más marcados tanto para la fluidez verbal fonética (-13,28%) como semántica (-12,40%). Para la Prueba de aprendizaje verbal auditivo Rey observamos un deterioro en la capacidad de recuerdo diferido (-10,12%) un año después de la cirugía. A los 5 años la mayor parte del deterioro se produjo en la fluidez verbal, con reducciones adicionales de 16,10% y 16,60% para la fluidez verbal semántica y fonética, respectivamente. Se observó un empeoramiento más moderado del recuerdo inmediato (-16,87%), WAIS III-LN (-16,67%) y de la prueba de orientación lineal de Benton (-11,56%). Discusión: La STN-DBS no condujo a deterioro cognitivo global a los 5 años de la cirugía. Hubo un deterioro significativo en la función verbal desde el primer año de la cirugía. El deterioro de la capacidad de aprendizaje y de las funciones visuoespaciales podría atribuirse al propio proceso degenerativo de la enfermedad

OBJECTIVE: The aim of this study was to evaluate the effects of deep brain stimulation of the subthalamic nucleus (DBS-SN) on cognitive function in patients with Parkinson's disease (PD) 5 years after surgery. MATERIAL AND METHODS: We conducted a prospective study including 50 patients with PD who underwent DBS-SN (62.5% were men; mean age of 62.2 ± 8.2 years; mean progression time of 14.1 ± 6.3 years). All patients were assessed before the procedure and at one year after surgery; 40 patients were further followed up until the 5-year mark. Follow-up assessments included the following neuropsychological tests: Mini-Mental State Examination (MMSE), Mattis Dementia Rating Scale (MDRS), letter-number sequencing of the WAIS-III (WAIS-III-LN), clock-drawing test, Rey auditory verbal learning test (RAVLT), Benton Visual Retention Test (BVRT), Judgment of Line Orientation (JLO) test, FAS Phonemic Verbal Fluency Test, Stroop test, and the Montgomery-Asberg Depression Rating Scale (MADRS). RESULTS: Patients were found to score lower on the MMSE (-0.89%), clock-drawing test (-2.61%), MDRS (-1.72%), and especially phonemic (-13.28%) and sematic verbal fluency tests (-12.40%) at one year after surgery. Delayed recall on the RAVLT worsened one year after the procedure (-10.12%). At 5 years, impairment affected mainly verbal fluency; scores decreased an additional 16.10% and 16.60% in semantic and phonemic verbal fluency, respectively. Moderate decreases were observed in immediate recall (-16.87%), WAIS-III-LN (-16.67%), and JLO test (-11.56%). Discussion: In our sample, DBS-SN did not result in global cognitive impairment 5 years after surgery. Verbal function was found to be significantly impaired one year after the procedure. Impaired learning and visuospatial function may be attributed to degeneration associated with PD

Long-term impact of subthalamic stimulation on cognitive function in patients with advanced Parkinson's disease. / Impacto de la estimulación subtalámica a largo plazo sobre la situación cognitiva de los pacientes con enfermedad de Parkinson avanzada.

OBJECTIVE: The aim of this study was to evaluate the effects of deep brain stimulation of the subthalamic nucleus (DBS-SN) on cognitive function in patients with Parkinson's disease (PD) 5 years after surgery. MATERIAL AND METHODS: We conducted a prospective study including 50 patients with PD who underwent DBS-SN (62.5% were men; mean age of 62.2±8.2 years; mean progression time of 14.1±6.3 years). All patients were assessed before the procedure and at one year after surgery; 40 patients were further followed up until the 5-year mark. Follow-up assessments included the following neuropsychological tests: Mini-Mental State Examination (MMSE), Mattis Dementia Rating Scale (MDRS), letter-number sequencing of the WAIS-III (WAIS-III-LN), clock-drawing test, Rey auditory verbal learning test (RAVLT), Benton Visual Retention Test (BVRT), Judgment of Line Orientation (JLO) test, FAS Phonemic Verbal Fluency Test, Stroop test, and the Montgomery-Asberg Depression Rating Scale (MADRS). RESULTS: Patients were found to score lower on the MMSE (-0.89%), clock-drawing test (-2.61%), MDRS (-1.72%), and especially phonemic (-13.28%) and sematic verbal fluency tests (-12.40%) at one year after surgery. Delayed recall on the RAVLT worsened one year after the procedure (-10.12%). At 5 years, impairment affected mainly verbal fluency; scores decreased an additional 16.10% and 16.60% in semantic and phonemic verbal fluency, respectively. Moderate decreases were observed in immediate recall (-16.87%), WAIS-III-LN (-16.67%), and JLO test (-11.56%). DISCUSSION: In our sample, DBS-SN did not result in global cognitive impairment 5 years after surgery. Verbal function was found to be significantly impaired one year after the procedure. Impaired learning and visuospatial function may be attributed to degeneration associated with PD.

Full elastic constitutive relation of non-isotropic aligned-CNT/PDMS flexible nanocomposites.

The elastic response of vertically aligned-carbon nanotube/polydimethylsiloxane (A-CNT/PDMS) nanocomposites is presented in this study and related to the underlying aligned-CNT morphology. Multiwalled carbon nanotubes (MWCNTs) at 1% Vf are embedded in a flexible substrate of PDMS to create a flexible polymer nanocomposite (PNC). The PNC properties are evaluated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and tensile mechanical tests, and the full linearly elastic constitutive relation is established for such a PNC. The results suggest that the CNTs retain the alignment after wetting and curing of PDMS. PDMS is significantly modified by the reinforcing aligned-CNT fibers, demonstrating non-isotropic (as opposed to the isotropic neat PDMS) elastic properties all different from PDMS (Young's modulus of 0.8 MPa), including an anisotropy ratio of 4.8 and increases in the modulus of A-CNT/PDMS over PDMS by more than 900% and 100%, in the CNT longitudinal and transverse directions, respectively. This study reports the first full constitutive relation that may be useful in modeling PNCs as composites or as elements of hierarchical nanoengineered composites, particularly PDMS-CNT PNCs are envisioned as elements in biomedical devices such as pressure transducers and energy harvesters.

Flexible sensor for blood pressure measurement.

A new approach for the design and fabrication of a highly flexible blood pressure sensor is introduced in this paper. The goal is to measure the pressure within an aneurysm sac for post-endovascular aneurysms repair (EVAR) surveillance. Biocompatible polydimethylsiloxane (PDMS) membranes with embedded aligned carbon nanotubes (CNTs) are used to build the conductive elements of the pressure sensitive capacitor and the inductor for telemetry. Inductive coupling will be used to measure the internal capacitive variations. Fabricated test sensors validate the approach and demonstrate that CNTs/PDMS technology can be used to build highly flexible pressure sensors.

High-yield growth of vertically aligned carbon nanotubes on a continuously moving substrate.

Vertically aligned carbon nanotube (CNT) arrays are grown on a moving substrate, demonstrating continuous growth of nanoscale materials with long-range order. A cold-wall chamber with an oscillating moving platform is used to locally heat a silicon growth substrate coated with an Fe/Al2O3 catalyst film for CNT growth via chemical vapor deposition. The reactant gases are introduced over the substrate through a directed nozzle to attain high-yield CNT growth. Aligned multi-wall carbon nanotube arrays (or 'forests') with heights of approximately 1 mm are achieved at substrate speeds up to 2.4 mm s(-1). Arrays grown on moving substrates at different velocities are studied in order to identify potential physical limitations of repeatable and fast growth on a continuous basis. No significant differences are noted between static and moving growth as characterized by scanning electron microscopy and Raman spectroscopy, although overall growth height is marginally reduced at the highest substrate velocity. CNT arrays produced on moving substrates are also found to be comparable to those produced through well-characterized batch processes consistent with a base-growth mechanism. Growth parameters required for the moving furnace are found to differ only slightly from those used in a comparable batch process; thermal uniformity appears to be the critical parameter for achieving large-area uniform array growth. If the continuous-growth technology is combined with a reaction zone isolation scheme common in other types of processing (e.g., in the manufacture of carbon fibers), large-scale dense and aligned CNT arrays may be efficiently grown and harvested for numerous applications including providing interlayers for advanced composite reinforcement and improved electrical and thermal transport.

[Bilateral subthalamic nucleus deep-brain stimulation (STN-DBS) in Parkinson's disease: initial experience in Cruces Hospital]. / Estimulación bilateral del núcelo subtalámico en la enfermedad de Parkinson. Experiencia inicial en el Hospital de Cruces.

INTRODUCTION: Clinical outcomes of Parkinson's disease patients treated for 12 months with STN-DBS were analyzed. PATIENTS ADN METHODS: Twelve patients were selected using the CAPSIT protocol criteria and placement of electrodes in the appropriate target was performed according to results of fusion image techniques and intraoperative microrecording. RESULTS: A reduction in motor UPDRS (44 %) and activities of daily living (58 %) scores during <> phases were observed. <> time with dyskinesias was reduced (86 %), while severe dyskinesias disappeared. Levodopa dosage was also lowered (44 %). Patients and caregivers showed a clear-cut benefit on quality of life (58 % and 61 % respectively). No cognitive deterioration was observed and morbidity was in the same range as that published by other teams. CONCLUSION: Bilateral STN-DBS is an effective symptomatic therapy for complicated Parkinsons disease patients. It improves the quality of life of patients and their caregivers and allows a reduction of levodopa dosage.

Estimulación bilateral del núcleo subtalámico en la enfermedad de Parkinson. Experiencia inicial en el Hospital de Cruces / Bilateral subthalamic nucleus deep-brain stimulation (STN-DBS) in Parkinson's disease: initial experience in Cruces Hospital

Introducción: Se presentan los resultados clínicos tras 1 año de evolución en 12 pacientes con enfermedad de Parkinson tratados con estimulación bilateral de núcleo subtalámico. Pacientes y métodos: Los pacientes han sido seleccionados y estudiados de acuerdo con el protocolo CAPSIT y la colocación de los electrodos se ha realizado con el apoyo de técnicas de fusión de imagen y microrregistro intraoperatorio. Resultados: Se ha observado una mejoría clínica significativa en la intensidad del off, tanto en actividades de la vida diaria (58 por ciento) como en el aspecto motor (44 por ciento), ha disminuido el tiempo de discinesias (86 por ciento), con desaparición total de las discinesias graves, y se ha reducido en un 44 por ciento la dosis equivalente de levodopa del tratamiento médico. Se ha observado también una mejoría del 58 por ciento en la calidad de vida de los pacientes, así como un beneficio de un 61 por ciento en la calidad de vida de los cuidadores. No se ha observado deterioro cognitivo y la morbilidad ha sido similar a la de otros equipos quirúrgicos. Conclusión: La estimulación bilateral del núcleo subtalámico en la enfermedad de Parkinson evolucionada es una terapia eficaz que mejora la calidad de vida de los pacientes y de sus cuidadores y permite la reducción de dosis de levodopa (AU)

Postoperative follow-up of pituitary adenomas after trans-sphenoidal resection: MRI and clinical correlation.

Our purpose was to correlate the morphological changes seen on MRI studies of the sellar region after trans-sphenoidal resection of pituitary adenomas with clinical and hormonal studies. Between January 1993 and March 1994, 16 patients with a pituitary adenoma (9 macroadenomas and 7 microadenomas) were subjected to trans-sphenoidal resection and included in a prospective study. The protocol consisted of MRI, hormonal and visual studies at the following times: immediately postoperative (1st week), 1st month, 4th month and 1st year after surgery. The evolution of the contents of the sella turcica (tumour remnant, packing material and gland tissue), effects on the infundibulum, optic chiasm, cavernous sinus and sphenoid sinus were correlated with the clinical and hormonal studies. Stabilisation of the postsurgical changes occurred by the 4th month. Tumour remnants were noted in the immediate postoperative period in macroadenomas. Compression of the infundibulum was the only reliable indicator of possible involvement. Optic chiasm compression, defined as close contact between the chiasm and the tumour, was the only morphological finding that indicated visual impairment. There was no standard repneumatisation pattern in the sphenoid sinus, since mucosal changes resembling sinusitis were one of the postsurgical changes. We found MRI not to be useful for follow-up of microadenomas.

Arteriovenous fistulas in the neck: diagnosis with color Doppler sonography.

We report the use of color Doppler imaging in the diagnosis of four arteriovenous fistulas in the neck region: two had a traumatic origin and two were spontaneous. A perivascular color artifact was the most common initial finding on color images to indicate the underlying abnormality. In all four cases, a low-resistance flow with high systolic and diastolic velocities was observed in the feeding artery. Although angiography remains essential before therapeutic embolization, color Doppler sonography may be an important tool for screening and follow-up of cervical arteriovenous fistulas.

Tumor trofoblástico del lecho placentario de útero reporte de un caso / Placental site trophoblastic tumor of the uterus: report of the case

Describimos un caso de tumor trofoblástico del lecho placentario del útero haciendo énfasis en su patrón histopatológico, el cual fue diagnosticado en una paciente de veintiocho años, histerectimizada por hemorragia genital en su puerperio inmediato de un parto quirúrgico. Así mismo, hacemos comentario acerca del diagnóstico y manejo de esta entidad, luego de revisar bibliografia nacional e internacional

Inversión uterina en la Maternidad "Concepción Palacios" / Uterine inversion in the Concepcion Palacios Maternity

Se analizaron las caraterísticas clínicas de 110 casos de inversión uterina puerperal ocurridas en la Maternidad Concepción Palacios entre 1967 y 1981. La incidencia fue de 1 inversión por cada 4.670 partos. No existió diferencia significativa en relación a edad materna, paridad, duración del trabajo de parto respecto al grupo control (p>0,05). El tercer período fue descrito como "espontáneo" en 44 pacientes (48,35%), y como "provocado" en 47 (51,65%). Un 59,38% (57 pacientes), prtesentó inversión de grado IV. Hemorragia que ameritó uso de sangre y derivados ocurrió en el 43,63% y shock en el 18,18% de la población estudiada. La reducción manual con anestesia general, el manejo adecuado del shock, de la anemia aguda y de la hipotonía uterina fueron la base de nuestro tratamiento. Solamente se administró antibióticos en el 23,60%. Se reportaron dos histerectomías debidas a hipotonía uterina y a fracaso en la reducción manual, siendo éstas total y subtotal vaginal, respectivamente. la mortalidad fue del 0,91% (1 caso) debido a sepsis post-histerectomía total. El conocimiento de la entidad y el tratamiento adecuado constituyeron la causa para una menor morbimortalidad. El promedio de días de hospitalización fue de 5 días, siendo esta diferencia significativa respecto al grupo control (P< 0,01)

Embarazo tubárico bilateral simultáneo: reporte de un caso / Simultaneous bilateral tubal pregnancy: report of a case

Describimos un caso de embarazo tubárico bilateral simultáneo, con reporte anatomopatológico respectivo, basado en los criterios de Fishback y Norris. Así mismo, se realizan comentarios acerca de la incidencia y etiopatogenia de la afección, luego de revisar bibliografía nacional e internacional