Conversion of methanol to hydrocarbons over zeolite ZSM-23 (MTT): exceptional effects of particle size on catalyst lifetime.

A variety of synthetic procedures have been used to obtain zeolite ZSM-23 (MTT) catalysts with crystallite sizes ranging from the micrometer to nanometer scale. When the acidic zeolite is used as a catalyst for the methanol to hydrocarbon (MTH) reaction, the catalytic lifetime is dramatically influenced by the crystallite shape and size.

Valor nutritivo e cinética de degradação in vitro de genótipos de capim-elefante (Penissetum purpureum Schumach) sob dois intervalos de desfolhação e duas alturas de resíduo pós-pastejo / Nutritive value and in vitro kinetics degradation of elephant grass genotypes (Penissetum purpureum Schumach) under two intervals of defoliation and two post-grazing heights

O experimento foi conduzido na Embrapa Gado de Leite, em Coronel Pacheco, MG, com o objetivo de avaliar o valor nutritivo e a cinética de degradação in vitro de genótipos de capim-elefante submetidos ao pastejo, usando-se a técnica de mob-grazing. Utilizou-se a combinação fatorial (2x2x2), sendo dois genótipos de capim-elefante (BRS Kurumi e CNPGL 00-1-3), duas interceptações luminosas (IL) à entrada dos animais nos piquetes (90 e 95%) e duas alturas de resíduo pós-pastejo (30 e 50cm), dispostos num delineamento inteiramente ao acaso, com três repetições. Para o pastejo, foram usadas 24 novilhas mestiças Holandês x Zebu, com 190kg. O genótipo BRS Kurumi apresentou maior teor de PB (15,65%), menor teor de FDN (60,35%), maior coeficiente de digestibilidade (70,04%) e mais alta taxa de degradação (2,62% h1) em relação ao outro genótipo, quando manejados a 90% IL. O manejo a 95% de IL e resíduo de 30cm favoreceu mais altos teores de PB (14,04%) e coeficientes de DIVMS (69,81%) e mais baixos teores de FDN (60,61%), independentemente do genótipo. Assim, recomenda-se a utilização do genótipo Kurumi, manejado a 90% de IL e resíduo de 30cm, quando se leva em consideração o valor nutritivo da forragem.(AU)

The experiment was conducted at Embrapa Gado de Leite, Coronel Pacheco, MG, to evaluate the nutritive value and the in vitro kinetics of degradation of elephant grass genotypes under rotational grazing. The treatments consisted of a factorial combination (2x2x2), two genotypes of elephant grass (BRS Kurumi and CNPGL 00-1-3), two light interceptions (LI) at initiation of grazing (90 and 95%) and two post-grazing heights (30 and 50cm), arranged in a completely randomized design with three replications. Grazing animals were 24 Holstein Zebu crossbred heifers with 190kg BW. The genotype BRS Kurumi has a higher CP content (15.65%), lower NDF content (60.35%), higher digestibility (70.04%) and higher rate of degradation (2.62% h-1) in relation to CNPGL 00-1-3 when managed under 90% of LI. The management based on 95% of LI and 30cm of residual height promote higher CP content (14.04%) and coefficient of IVDMD (69.81%), as well as lower NDF content (60.61%), regardless of genotype. Thus, taking into account the nutritional value of forage, it is recommended to use the genotype BRS Kurumi managed under 90% of LI and 30cm of post-grazing residue.(AU)

["Off pump" coronary surgery and simultaneous carotid endarterectomy]. / Cirurgia coronária sem cec e endarterectomia carotídea simultânea.

The occurrence of significant carotid artery disease in patients requiring coronary artery bypass grafting (CABG), results in a dilemma regarding the best surgical management. Our philosophy has been to perform simultaneous carotid endarterectomy and CABG off-pump. We reviewed the efficacy of this therapy in six patients treated in our hospital between January 2001 and December 2002. The result was satisfactory and there was no hospital mortality.

Analysis of RPGR in a South African family with X-linked retinitis pigmentosa: research and diagnostic implications.

Analysis of exon ORF15 of the RPGR gene has revealed a novel mutation in a South African family with X-linked retinitis pigmentosa (XLRP), which has implications for the rest of the family in terms of pre-symptomatic testing. The ability to test for this mutation will be beneficial for the accurate determination of carrier status in female relatives who may have been unaware of their risk before this study was performed. This work also highlights the need to be aware of the ramifications of mutation testing in what may appear to be small families. This is the first report of an RPGR ORF15 mutation in a South African family of mixed ancestry.

[Subisthmic aortic coarctation. Apropos a rare case of arterial hypertension]. / Coarctação subístmica da aorta. A propósito de um caso raro de hipertensão arterial.

An uncommon case of high blood pressure secondary to subisthmic aortic coarctation and cured surgically by arterial revascularization is reported. It is probably a congenital coarctation, because the extensive clinical evaluation and condition of the patient ruled out an acquired disease of the aorta, confirmed by the morphologic operative findings and pathological examinations of the aortic wall. In this case, the clinical diagnosis was initially suggested due to an abdominal systolic-diastolic bruit, associated to hypertension and weak femoral pulses. Although doppler ultrasonography and nuclear magnetic resonance were useful diagnostic tools, a complete angiography should be performed because it is currently the most informative technique to evaluate the aorta and its collaterals, frequently involved in association with subisthmic aortic coarctation. Surgical exploration revealed a hypoplastic descending thoracic aorta and histological data confirmed the nonexistence of acquired pathology of the aortic wall. Surgical management was accomplished successfully and the patient was asymptomatic 41 months after the operation with normal blood pressure, no treatment, and a normal pattern of life. Based on this presentation, the authors describe the etiology, morphology and anatomic classification, clinical manifestations, diagnosis and management of subisthmic aortic coarctation.