Catalytic Gasification and Reforming of Residual Biomass in a Bench Scale System with Low Cost Catalysts.

This paper demonstrates the effectiveness of using of different catalysts for reforming tars contained in the syngas of biomass gasifiers. The conversion of the tar content allows to obtain high quality syngas and to maximize the gas fraction. A bench scale equipment consisting of an autothermal fluidized bed gasifier and a downstream packed bed reformer was used. Pine sawdust was selected as the feedstock for gasification. TGA analysis showed that the temperature must be above 350 °C to ensure the ignition of the biomass and maintain the process in an autothermal steady-state. Dolomite and pyrolysis char were used to test of the fluidized bed catalysts. In the reformer, dolomite, pyrolysis char, iron doped activated carbon and spent HDS catalyst were used. All catalysts decreased the CO2 concentration in the product gas and increased H2 , CH4 and CO. When iron doped activated carbon is used, tar contents below 60 g/Nm3 in the product gas could be obtained, reaching less than 1 g/Nm3 . The best value of LHV (lower heating value) was obtained with pyrolysis char as a catalyst (4.8 MJ/Nm3 ). The results demonstrate that catalytic biomass gasification with downstream tar reforming with low-cost catalysts is a promising solution for energy applications.

In Situ DRIFTS Analysis during Hydrogenation of 1-Pentyne and Olefin Purification with Ag Nanoparticles.

The catalytic performance of nanoparticles (NPs) of Ag anchored on different supports was evaluated during the selective hydrogenation of 1-pentyne and the purification of a mixture of 1-pentene/1-pentyne (70/30 vol %). The catalysts were identified: Ag/Al (Ag supported on É£-Al2 O3 ), Ag/Al-Mg (Ag supported on É£-Al2 O3 modified with Mg), Ag/Ca (Ag supported on CaCO3 ) and Ag/RX3 (Ag supported on activated carbon-type: RX3). In addition, in situ DRIFTS analysis of 1-pentyne adsorption on each support, catalyst, and 1-pentyne hydrogenation were investigated. The results showed that the synthesized catalysts were active and very selective (≥85 %) for obtaining the desired product (1-pentene). Different adsorbed species (-C≡C- and -C=C-) were observed on the supports and catalysts surface using in situ DRIFT analysis, which can be correlated to the activity and high selectivity reached. The role of the supports and electronic properties over Ag improve the H2 dissociative chemisorption during the hydrogenation reactions; promoting the selectivity and the high catalytic performance. Ag/Al and Ag/Al-Mg were the most active catalysts. This was due to the synergism between the active Ag/Ag+ species and the supports (electronic effects). The results show that Ag/Al and Ag/Al-Mg catalysts have favorable properties and are promising for the alkyne hydrogenation and olefin purification reactions.

The Orbit as Seen Through Different Surgical Windows: Extensive Anatomosurgical Study.

A thorough understanding of the orbit, structures within it, and complex spatial relationships among these structures bears relevance in a variety of neurosurgical cases. We describe the 3-dimensional surgical anatomy of the orbit and fragile and complex network of neurovascular architectures, flanked by a series of muscular and glandular structures, found within the orbital dura.

Preoperative Stratification of Transsphenoidal Pituitary Surgery Patients Based on Surgical Urgency.

BACKGROUND: Currently, there is no prioritization scale available to distinguish those patients with pituitary tumors who require urgent surgical intervention from those who are candidates for elective treatment. OBJECTIVE: To develop a classification system that can help primary care physicians, endocrinologists, neurosurgeons, ancillary support staff, and hospital administrators identify high-priority surgical candidates. METHODS: An expert international panel of clinicians consisting of endocrinologists and neurosurgeons who are involved in the diagnosis and management of sellar disease was convened. The panel retrospectively reviewed individual experiences, including a cohort of patients operated upon for pituitary related disease at the Brigham and Women's Hospital from January 2008 to November 2015. A risk stratification schema was developed to streamline patient care pathways. RESULTS: We identified 4 groups of surgical candidates with varying levels of risk, and then assigned treatment timelines and different differential diagnoses to each. The 4 groups were as follows: group A: urgent-immediate; group B: prompt-initiate treatment within 1 to 2 weeks; group C: soon-initiate treatment within 3 months; group D: elective-as soon as indicated. Among 472 patients treated at Brigham and Women's Hospital for pituitary adenomas, each was assigned to 1 of the 4 predetermined subgroups: group A, 6.8%; group B, 30.1%; group C, 31.1%; group D, 32.0%. CONCLUSIONS: We developed a risk stratification schema that may serve as a platform to streamline care to the patients at highest risk. The expert opinions presented provide a basis for future studies regarding the risk prioritization of patients.

Metal and precursor effect during 1-heptyne selective hydrogenation using an activated carbon as support.

Palladium, platinum, and ruthenium supported on activated carbon were used as catalysts for the selective hydrogenation of 1-heptyne, a terminal alkyne. All catalysts were characterized by temperature programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. TPR and XPS suggest that the metal in all catalysts is reduced after the pretreatment with H2 at 673 K. The TPR trace of the PdNRX catalyst shows that the support surface groups are greatly modified as a consequence of the use of HNO3 during the catalyst preparation. During the hydrogenation of 1-heptyne, both palladium catalysts were more active and selective than the platinum and ruthenium catalysts. The activity order of the catalysts is as follows: PdClRX>PdNRX>PtClRX≫RuClRX. This superior performance of PdClRX was attributed in part to the total occupancy of the d electronic levels of the Pd metal that is supposed to promote the rupture of the H2 bond during the hydrogenation reaction. The activity differences between PdClRX and PdNRX catalysts could be attributed to a better accessibility of the substrate to the active sites, as a consequence of steric and electronic effects of the superficial support groups. The order for the selectivity to 1-heptene is as follows: PdClRX=PdNRX>RuClRX>PtClRX, and it can be mainly attributed to thermodynamic effects.

Minimally invasive supracondylar transtubercular (MIST) approach to the lower clivus.

OBJECTIVE: Drawbacks of the far-lateral approach to the lower clivus and pontomedullary region include the morbidity of a large incision extending into the cervical musculature and tedious exposure of the vertebral artery (VA), particularly when performing the transcondylar and transtubercular extensions. The authors describe a minimally invasive alternative to the far-lateral approach that has the potential to minimize operative morbidity and decrease the need for VA manipulation. METHODS: The minimally invasive supracondylar transtubercular (MIST) and far-lateral supracondylar transtubercular (FLST) approaches were performed in 10 adult cadaveric specimens (20 sides). The microsurgical anatomy of each step and the surgical views were analyzed and compared. In addition, the endoscopic view through the MIST was examined in five fresh cadaveric specimens (10 sides). RESULTS: The MIST approach provided exposure of the inferior-middle clivus, the anterolateral brainstem, and the premedullary cisterns, including the PICA-VA and vertebrobasilar junctions. The endoscope provided a clear view of cranial nerves III through XII, as well as the vertebrobasilar system. The FLST approach increased visualization of the anterolateral margin of the foramen magnum; otherwise, the surgical view is similar between the MIST and FLST approaches. CONCLUSIONS: The MIST approach could be considered as a potential alternative to the FLST approach in the treatment of lesions involving the inferior and middle clivus, and anterolateral lower brainstem; it does not require a C1 laminectomy, significant disruption of the atlanto-occipital joint, nor extensive exposure of the extracranial VA. Moreover, the MIST approach is an ideal companion to endoscope-assisted neurosurgery.

Normal anatomical variations of the V3 segment of the vertebral artery: surgical implications.

OBJECT: The authors undertook this cadaveric and angiographic study to examine the microsurgical anatomy of the V3 segment of the vertebral artery (VA) and its relationship to osseous landmarks. A detailed knowledge of these variations is important when performing common neurosurgical procedures such as the suboccipital craniotomy and the far-lateral approach and when placing atlantoaxial instrumentation. METHODS: A total of 30 adult cadaveric specimens (59 sides) were studied using magnification × 3 to × 40 after perfusion of the arteries and veins with colored silicone. Seventy-three vertebral angiograms were also analyzed. The morphological detail of the V3 segment was described and measured in both the cadavers and angiograms. Transarticular screws were placed into 2 cadavers and the relationship of the trajectory to the V3 segment was analyzed. RESULTS: The authors identified 4 sites along the V3 segment that are anatomically the most likely to be injured during surgical approaches to the craniovertebral junction. In 35% of the cadaveric specimens the vertical portion of V3 formed a posteriorly oriented loop that could be injured during surgical exposures of the dorsal surface of C-2. The mean distance from the midline to the most posteromedial edge of the loop was 25.6 ± 3.5 mm (range 20-35 mm) on the left side and 30.4 ± 3.8 mm (range 23-36 mm) on the right side. On lateral angiograms, this loop projected posteriorly, with a mean distance of 9.8 ± 3.5 mm (range 0-15.7 mm) on the right side and 11.7 ± 1.2 mm (range 10-13.6 mm) on the left side. The horizontal segment of V3 can be injured when exposing the lower lateral occipital bone and when the C-1 arch is exposed. The mean distance from the inferior border of the occipital bone to the superior surface of the horizontal segment of V3 was 6 ± 2.8 mm on the right side and 5.6 ± 2.3 mm on the left. In 12% of cases the authors found no space between the horizontal portion of V3 and the occipital bone. The medial edge of the horizontal segment of V3 was located 23 ± 5.5 mm (range 10-30 mm) from the midline on the right side and 24 ± 5.7 mm (range 15-32 mm) on the left side. The transition between the V2-V3 segments after exiting the C-2 vertebral foramen is the most likely site of injury when placing C1-2 transarticular screws or C-2 pars screws. CONCLUSIONS: The normal variation of the V3 segment of the VA has been described with quantitative measurements. An awareness of the anatomical variations and the relationships to the surrounding bony anatomy will aid in reducing VA injury during suboccipital approaches, exposure of the dorsal surfaces of C-1 and C-2, and when placing atlantoaxial spinal instrumentation.

Ultrahigh-dose intraarterial infusion of verapamil through an indwelling microcatheter for medically refractory severe vasospasm: initial experience. Clinical article.

OBJECT: Vasospasm is one of the leading causes of morbidity and death following aneurysmal subarachnoid hemorrhage (SAH). Many patients suffer devastating strokes despite the best medical therapy. Endovascular treatment is the last line of defense for cases of medically refractory vasospasm. The authors present a series of patients who were treated with a prolonged intraarterial infusion of verapamil through an in-dwelling microcatheter. METHODS: Over a 1-year period 12 patients with medically refractory vasospasm due to aneurysmal SAH were identified. Data were retrospectively collected, including age, sex, Hunt and Hess grade, Fisher grade, aneurysm location, aneurysm treatment, day of the onset of vasospasm, intracranial pressure, mean arterial pressures, intraarterial treatment of vasospasm, dosages and times of verapamil infusion, presence of a new ischemic area on CT scan, modified Rankin scale score at discharge and at the last clinical follow-up, and discharge status. RESULTS: Twenty-seven treatments were administered. Between 25 and 360 mg of verapamil was infused per vessel (average dose per vessel 164.6 mg, range of total dose per treatment 70-720 mg). Infusion times ranged from 1 to 20.5 hours (average 7.8 hours). The number of treated vessels ranged from 1 to 7 per patient. The number of treatments per patients ranged from 1 to 4. There was no treatment-related morbidity or death. Blood pressure and intracranial pressure changes were transient and rapidly reversible. Among the 36 treated vessels, prolonged verapamil infusion was completely effective in 32 cases and partially effective in 4. Only 4 vessels required angioplasty for refractory vasospasm after prolonged verapamil infusion. There was no CT scanning evidence of new ischemic events in 9 of the 12 patients treated. At last clinical follow-up 6-12 months after discharge, 8 of 11 patients had a modified Rankin Scale score ≤2. CONCLUSIONS: Prolonged intraarterial infusion of verapamil is a safe and effective treatment for medically refractory severe vasospasm and reduces the need for angioplasty in such cases.

Un caso de integración de TIC que no agrega valor al aprendizaje / Um caso de integração das Tecnologias de Informações e Comunicações (TIC) que não agregam valor à aprendizagem / A case of integration of Information and Communication Technologies that does not add value to learning

Pocos estudios cualitativos proveen información acerca del fenómeno de la integración de Tecnologías de Información y Comunicaciones (TIC) en educación superior. Este documento corresponde a uno de los 17 estudios de caso adelantados en una investigación adelantada para conocer más a profundidad este fenómeno e identificar aprendizajes de los estudiantes que participan de él. Los datos se recogieron a partir de observaciones no participantes a las clases durante un semestre académico, entrevistas semiestructuradas a la profesora y entrevistas y grupos focales con estudiantes. Adicionalmente se analizaron los trabajos de los estudiantes realizados con apoyo de TIC. Los datos fueron analizados mediante categorías deductivas e inductivas comunes a todos los casos y finalmente contextualizados. El caso descrito en este artículo se refiere al ambiente de aprendizaje construido por 16 estudiantes y su profesora donde se integraron las TIC coherentemente con la estrategia pedagógica pero no agregaron valor al proceso de aprendizaje. La descripción presenta patrones de comportamiento,concepciones y prácticas pedagógicas que para otros profesores pueden constituirse en elementos para tomar decisiones sobre cómo diseñar sus ambientes de aprendizaje con TIC y para motivarlos a reflexionar sobre sus propias prácticas pedagógicas.

Poucos estudos qualitativos fornecem informação acerca do fenômeno de integração de Tecnologias de Informação e Comunicações (TIC) na educação superior. Este documento corresponde a um dos 17 estudos de caso realizados numa pesquisa com o objetivo de conhecer com mais profundidade este fenômeno e identificar as aprendizagens dos estudantes que participaram nele. Os fatos foram recolhidos a partir de observações não participantes nas aulas durante um semestre acadêmico, entrevistas semi-estruturadas à professora e entrevistas e grupos focais com estudantes. Adicionalmente analisaram-se os trabalhos dos estudantes realizados com apoio das TIC. Os dados foram analisados mediante categorias dedutivas e indutivas comuns a todos os casos e depois foram contextualizados. O caso descrito neste artigo refere-se ao ambiente de aprendizagem construído por 16 estudantes e sua professora, onde foram integradas as TIC coerentemente com a estratégia pedagógica, mas não agregaram nenhum valor ao processo de aprendizagem. Esta descrição apresenta padrões de comportamento, conceições e práticas pedagógicas que para os outros professores podem constituir-se em elementos para a toma de decisões sobre como desenhar ambientes de aprendizagem com TIC e para motivá-los a refletir sobre as suas próprias práticas pedagógicas.

A few qualitative studies provide information about the integration of Information and Communication Technologies (TIC) into higher education. This article corresponds to one of the 17 case studies carried out in a research to know about this phenomenon more deeply and to identify the learning process of the students who participated in it. The data was collected from nonparticipant class observations to the classes in an academic semester, semi-structured interviews to the teacher and interviews and targeted groups with students. Additionally the works of the students were analyzed with the support of TIC’s. The data was analyzed with common deductive and inductive categories that were common to all the cases and was finally contextualized. The case described in this article talks about the learning environment constructed by 16 students and their professor, where she coherently integrated the TIC with her pedagogical strategy but did not add value to the learning process. The description presents behavior patterns, conceptions and pedagogical practices that other teachers can use as elements to make decisions about how to design their learning environments with TIC and to motivate them to reflect on their own pedagogical practices.

Submandibular approach to the C2-3 disc level: microsurgical anatomy with clinical application.

OBJECT: Approaching the C2-3 disc level is challenging because of its location behind the mandible and the vital neurovascular structures overlying the area. The purpose of this study was to illustrate in a stepwise fashion the microsurgical anatomy of the submandibular approach to the C2-3 disc. METHODS: Ten adult formalin-fixed cadaveric specimens (20 sides) were studied. Particular attention was paid to the structures limiting the exposure. The authors measured the distance between the inferior border of the mandible and the marginal mandibular branch of the facial nerve running inferior to the mandible, the distance between the horizontal segment of the hypoglossal nerve and the hyoid bone, and the distance between the horizontal segment of the hypoglossal nerve and the mandible. They compared the location of the superior laryngeal nerve with regard to the submandibular and the standard Smith-Robinson approaches. A clinical case illustrating the usefulness of the surgical technique in this region is presented. RESULTS: The mean distance between the inferior border of the mandible and the lowest point of the marginal mandibular branch of the facial nerve was 6.7 +/- 1.69 mm. The hypoglossal nerve's mean distance above the hyoid bone was 8.4 +/- 1.78 mm and below the mandible was 19.6 +/- 6.39 mm. The internal branch of the superior laryngeal nerve, with respect to the cervical spine, always entered the thyrohyoid membrane just inferior to the C-3 vertebral body. The superior laryngeal nerve was found to be an impediment to approaching the C2-3 disc through the standard Smith-Robinson approach. CONCLUSIONS: The submandibular approach provides excellent exposure, with a perpendicular view of the C2-3 disc level. This approach is one of the options to be considered when dealing with high cervical pathologies.

Reporte de un caso de la sesión de casos clínicos de la Asociación de Costarricense de Ciencias Neurológicas: sesión del 17 de mayo del 2000 / Report one case of the sesion clinics cases of the Asociación de Costarricense de Ciencias Neurológicas: sesion of 17 may 2000

Los autores reportan el caso de un paciente de 68 años de edad que presentó un episodio de crisis convulsiva contínua del miembro inferior derecho. La resonancia magnética demostró múltiples lesiones en ambos hemisferios cerebrales, especialmente en el lado izquierdo. Una de las lesiones presentaba una imagen de anillo cerrado que se acentuaba con contraste. El paciente presentó varios episodios de déficits focales posteriormente. Las pruebas de HIV, sífilis, toxoplasmosis y cistercosis resultaron negativas, el LCR fue normal y no se encontró fuente embolígena ni neoplásica. Una biopsia cerebral por aguja estableció el diagnóstico de glioma multicéntrico. Palabras clave: glioma multicéntrico, neuroimágenes, crisis convulsiva

Reporte de un caso de la sesión de casos clínicos de la Asociación de Costarricense de Ciencias Neurológicas: sesión del 24 de agosto del 2000 / Report one case of the sesion of clinics cases of the Asociación de Costarricense de Ciencias Neurológicas: sesion of the Agost 24, 2000

Se ha comprobado que los ateromas aórticos son un factor de riesgo independiente para accidentes cerebrovasculares. La ecocardiografía transesofágica es un método útil para diagnosticar estas lesiones, y debería ser incluído en la evaluación de pacientes que han presentado isquemias cerebrales. Los autores reportan el caso de un paciente que presentó dos episodios de hemiparesia derecha dentro de 24 horas. El paciente no tenía fibrilación atrial ni estenosis carotídea, y el estudio TAC no mostró anormalidades. Durante el segundo episodio, mediante dopplersonografía transcraneal, en la arteria cerebral media. Una ecocardiografía transesofágica confirmó la presencia de un ateroma aórtico complicado. Palabras claves: ateroma aórtico; accidente cerebrovascular, ecocardiografía, ultrasonografía

Giardiasis en preescolares del area metropolitana de Caracas / Giardiasis in preschool of the urban area of Caracas

Se tomaron muestras de heces de 250 niños del Area Metropolitana de Caracas, con edades entre 1 y 5 años, 232 (92,8 por ciento) presentaron tos, prurito anal, bruxismo, dolor abdominal y anorexia. 18 (7,2 por ciento) estaban asintomáticos. Las muestras se recolectaron entre julio y septiembre, conservándose con líquido de Railliet- Henry, coloreados con lugol, tricrómico y clorazol y examinados por microscopía. Los parásitos encontrados con más frecuencia fueron: Entamoeba histolytica, Giardia lamblia y Amoebas no Patógenas. 37,4 por ciento de las muestras presentaban un sólo agente y 62 por ciento mostraban infección mixta, siendo esta diferencia significativa 43,2 por ciento de las muestras tenían Giardia lamblia. Para las parasitosis múltiples, en las que Giardia lamblia figuraba como uno de los agentes parasitarios (86 casos), su asociación con otros protozoarios fue la más importante, 82 casos 95,3 por ciento), de los cuales 94,4 por ciento son varones y 96,9 por ciento son hembras, siendo esta diferencia significativa. La población estudiada resultó ser hemogénea en relación a la presencia de Giardia lamblia y sexo, edad, grupo sanguíneo y factor Rh. La elevada incidencia de parasitosis se explica por: 1) condiciones higiénicas inadecuadas; 2) resistencia de los quistes de Giardia lamblia a factores ambientales; 3) época del año en que se recolectaron las muestras; 4) los protozoarios intestinales tienen un mecanismo de transmisión común

Criptosporidiosis en preescolares de tres guarderias del área metropolitana de Caracas / Criptosporidiosis in preeshool of three, keepership the urban area of Caracas

Para el presente trabajo se seleccionaron 268 niños quienes provienen de diferentes zonas marginales de la ciudad de Caracas y acuden diariamenme a tres instituciones educativas subsidiadas por la Alcaldía de Caracas. Entre los meses de julio, agosto y septiembre se tomó de cada niño una muestra de heces, la cual fue fijada con Metanol y coloreada con la técnica de Kinyoun, para luego identificar las diferentes formas evolutivas de Cryptosporidium sp. De las muestras examinadas se constató la presencia de Cryptosporidium sp. en 128 (47,8 por ciento) en tanto que en 140 (52,2 por ciento) resultaron negativas para este mismo protozoario. La alta incidencia de Cryptosporidiosis puede explicarse por la época del año en que se recolectaron las muestras y las inadecuadas condiciones higiénicas en las que se desenvuelve esta población