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Fluid bed drying of guarana ( Paullinia cupana HBK) extract: Effect of process factors on caffeine content

February 02, 2009 By: admin Category: Health Sciences, Medicine and Dentistry

The aim of this study was to study the convective drying of the hydroalcoholic extracts obtained from powdered guarana seeds in a spouted bed dryer. The influence of process variables, such as the convective airflow rate, extract feed rate,; air inlet temperature, on the quality of the dry extract was determined using the caffeine; moisture content for the process evaluation. The caffeine content in the alcoholic; dried extracts was determined by capillary gas chromatography. The experiments were performed following a 3[3] factorial design; the data analyzed by response surface. The analysis of dry extract showed that the air; extract feed rates did not significantly affect (25% level) the caffeine content, but that drying temperature is a major factor to consider when the extract is submitted to fluid bed drying. Caffeine losses were significant (1% level) for drying temperatures above 120°C, while moisture content was lower than 3% for temperatures above 120°C. The data showed that there is an optimum temperature for the drying of guarana extracts in spouted beds,; under the conditions used in this study it was 120°C.

Renata S. Pagliarussi1?Jairo K. Bastos1?Luis A. P. Freitas1Email:lapdfrei@usp.br
[1] Faculdade de Ciências Farmacêuticas de Ribeiro Preto, Universidade de So Paulo, Via do Café s/n, 14040-903 Ribeiro Preto, So Paulo, Brazil

Fast-disintegrating sublingual tablets: Effect of epinephrine load on tablet characteristics

February 02, 2009 By: admin Category: Health Sciences, Medicine and Dentistry

The aim of this study was to evaluate the effect of increasing epinephrine load on the characteristics of fast-disintegrating sublingual tablets for the potential emergency treatment of anaphylaxis. Four tablet formulations, A, B, C,; D, containing 0%, 6%, 12%,; 24% of epinephrine bitartrate, respectively,; microcrystalline cellulose:low-substituted hydroxypropyl cellulose (9?1), were prepared by direct compression, at a range of compression forces. Tablet weight variation, content uniformity, hardness, disintegration time, wetting time,; friability were measured for each formulation at each compression force. All 4 tablet formulations at each compression force were within the United States Pharmacopeia (USP) limits for weight variation; content uniformity. A linear increase in compression force resulted in an exponential increase in hardness for all formulations, a linear increase in disintegration; wetting times of A,; an exponential increase in disintegration; wetting times of B, C,; D. At a mean±SD hardness of ?2.3±0.2 kg, all tablet formulations passed the USP friability test. At a mean±SD hardness of ?3.1±0.2 kg, all tablet formulations resulted in disintegration; wetting times of >10 seconds; >30 seconds, respectively. Tablets with drug loads from 0% to 24% epinephrine can be formulated with hardness, disintegration times,; wetting times suitable for sublingual administration.

Mutasem M. Rawas-Qalaji1?F. Estelle2?R. Simons2?Keith J. Simons3Email:simons@ms.umanitoba.ca
[1] Faculty of Pharmacy, University of Manitoba, Winnipeg, Manitoba, Canada ;[2] Section of Allergy; Clinical Immunology, Department of Pediatrics; Child Health, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada ;[3] Faculty of Pharmacy, Department of Pediatrics; Child Health, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada

Ferroelastic domain switching fatigue in lead zirconate titanate ceramics

September 17, 2008 By: admin Category: Materials Science, Physical Sciences and Engineering

The influence of the frequency and amplitude of cyclic mechanical loading on soft, tetragonal lead zirconate titanate (PZT) ceramics was investigated via neutron diffraction. Intensity change in the {2 0 0} reflections provided quantitative measurements of domain switching behavior, domain texture and the strain resulting from domain switching. The results are explained using a viscoelasticity model. It was found that the magnitude of applied stress affects the level of strain accumulated, while its frequency affects the time taken for the strain to reach saturation. Furthermore, markedly different behaviors are exhibited by poled and unpoled samples. For samples loaded under identical conditions, the frequency effect is more pronounced in unpoled samples and the accumulated ferroelastic strain is greater in poled samples.

Soodkhet Pojprapai ImlaoEmail:soodkhet@student.unsw.edu.au?Jacob L. Jonesb?Andrew J. Studerc?Jennifer Russella?Nagarajan Valanoora?Mark Hoffmana
[a]School of Materials Science; Engineering, University of New South Wales, Sydney, NSW 2052, Australia;[b]Department of Materials Science; Engineering, University of Florida, Gainesville, FL, USA;[c]Bragg Institute, Australian Nuclear Science; Technology Organisation, Sydney, NSW, Australia

Finite element simulation of quench distortion in a low-alloy steel incorporating transformation kinetics

September 17, 2008 By: admin Category: Materials Science, Physical Sciences and Engineering

The uncontrolled distortion of steel parts has been a long-standing and serious problem for heat treatment processes, especially quenching. To get a better understanding of distortion, the relationship between transformation kinetics and associated distortion has been investigated using a low-alloy chromium steel. Because martensite is a major phase transformed during the quenching of steel parts and is influential in the distortion, a new martensite start (Ms) temperature and a martensite kinetics equation are proposed. Oil quenching experiments with an asymmetrically cut cylinder were conducted to confirm the effect of phase transformations on distortion. ABAQUS and its user-defined subroutines UMAT and UMATHT were used for finite element method (FEM) analysis. The predictions of the FEM simulation compare well with the measured data. The simulation results allow for a clear understanding of the relationship between the transformation kinetics and distortion.

Seok-Jae Leea?Young-Kook Leeb Email:yklee@yonsei.ac.kr
[a]Research Institute of Iron; Steel Technology, Yonsei University, Seoul 120-749, Republic of Korea;[b]Department of Metallurgical Engineering, Yonsei University, Seoul 120-749, Republic of Korea

Features of feathery ? structure in a near-? TiAl alloy

September 17, 2008 By: admin Category: Materials Science, Physical Sciences and Engineering

This work characterizes the feathery-like structures produced in a Ti–46.8Al–1.7Cr–1.8Nb (at.%) alloy during rapid continuous cooling from the domain. Their morphology and crystallography are described using different microscopy and orientation mapping techniques. These feathery-like structures are divided into many small domains, characterized by low-angle misorientations (rotated less than 15°) between the domains. The domains comprise multiple parallel ? lamellae and rare traces of 2. These lamellae follow the Blackburn orientation relationship and have a {1 1 1}? habit plane. Two types of ?-feathery structures were identified according to their location and crystallography. The grain-boundary ?-feathery structures originate from lamellar structures that grow into a neighboring grain. Alternatively, the internal ?-feathery structures are located in the interior of prior grains and show an average misorientation of 36° around one axis of the lamellar structure in which it is embedded. This paper describes these two ?-feathery structures in detail and discusses their development in light of the mechanisms available in the literature, particularly sympathetic nucleation.

S.R. Dey1?E. Bouzya?A. Hazotte aEmail:alain.hazotte@univ-metz.fr
[a]Laboratoire d’Etude des Textures et Application aux Matériaux, UMR CNRS/UPVM 7078, Ile du Saulcy, 57045 Metz Cedex 1, France

Fault zone deformation controlled by carbonate mechanical stratigraphy, Balcones fault system, Texas

September 17, 2008 By: admin Category: Engineering, Energy and Technology, Physical Sciences and Engineering

Normal faults in Cretaceous carbonates in the Balcones fault system provide important analogs for fault zone architecture and deformation in carbonate reservoirs worldwide. Mechanical layering is a fundamental control on carbonate fault zones. Relatively planar faults with low-displacement gradients develop in massive, strong, clay-poor limestones and dolomites. In less competent clay-rich strata, shale beds impede fault propagation, resulting in fault-related folding, and locally steep bedding dips. Faults in clay-poor massive limestones and dolomites tend to be steep (70° or more), whereas weaker, clay-rich limestones develop faults with shallower dips (60° or less). Fault zone rocks show evidence of cataclasis, cementation, deformation of cement by mechanical twinning and pressure solution, and multiple generations of cement with differing degrees of deformation, indicating contemporaneous cementation and fault slip. In stratigraphic sequences consisting of both competent and incompetent strata, the ratio of incompetent to competent strata by thickness is a useful guide for inferring the relative rates of fault displacement and propagation. Low displacement-to-propagation ratios associated with competent strata generate low-displacement gradients, inhibiting fault-related folding. Conversely, high displacement-to-propagation ratios associated with incompetent strata promote high-displacement gradients and fault-related folding.

David A. Ferrill?Alan P. Morris
Geosciences and Engineering Division, Department of Earth, Material, and Planetary Sciences, Southwest Research Institute~R, 6220 Culebra Road, San Antonio, Texas 78238

Fades architecture of a net transgressive sandstone reservoir analog: The Cretaceous Hosta Tongue, New Mexico

September 17, 2008 By: admin Category: Engineering, Energy and Technology, Physical Sciences and Engineering

Net transgressive sandstones form a significant component of many shallow-marine reservoirs, but their shale-poor character commonly masks complex facies architecture and stratigraphy associated with significant permeability variations that impact reservoir drainage patterns and ultimate recovery. In this article, the controls on net transgressive sandstone reservoir architecture are investigated through a detailed analysis of the Cretaceous Hosta Tongue of the Point Lookout Sandstone (informally termed Hosta sandstone in this article] outcrop in New Mexico. Mapping of facies architecture within a series of adjacent canyons has enabled a quantitative three-dimensional reconstruction of key stratigraphic surfaces and sand body distributions from an updip pinch-out to a downdip pinch-out of the net transgressive sandstone complex. The Hosta sandstone contains a complex arrangement of wave-and tide-dominated facies associations arranged in an overall transgressive pattern. Tidal channel-fill sandstones, tidal sheet-form sandstones, and heterolithic tidal-flat and lagoonal deposits comprise the stratigraphy in the updip part of the system. These deposits pass abruptly downdip into wave-dominated shoreface sandstones. The facies composition indicates that the Hosta sandstone represents a wave-dominated barrier shoreline and a tide-dominated back-barrier lagoon. Facies associations are partitioned both vertically and laterally by a hierarchy of transgressive erosion (ravinement) surfaces cut by wave and tidal processes. Reconstructing the geomorphol-ogy and spatial organization of these surfaces is critical to understanding sand body distribution and facies architecture at high-resolution (intrareservoir) scale.

Peter J. Sixsmith?Gary J. Hampson?Sanjeev Gupta
Department of Earth Science and Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom

FROM START TO FINISH

September 17, 2008 By: admin Category: Social Sciences, Social Sciences and Humanities

The author of our popular “Litigation” column explains how to win over jurors in opening and closing statements. Find out why you shouldn’t talk like a lawyer, how you can deal with implausible facts, and more.

James W. McElhaney

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