Effect of drying and storage on the degradation of total carotenoids in orange‐fleshed sweetpotato cultivars

BACKGROUND: Orange‐fleshed sweetpotato (OFSP) can be used to tackle vitamin A deficiency, a major public health problem in most developing countries. In East Africa, common ways of using sweetpotato include drying and subsequent storage. The aim of the study was to investigate the impact of drying and storage on the total carotenoid retention (as an estimate of provitamin A retention) from OFSP. RESULTS: Losses of total carotenoid during drying were generally low (15% or less). Total carotenoid retention in OFSP was not dependent on the type of dryer (solar or sun). Sweetpotato cultivar (Ejumula, Kakamega, SPK004/1, SPK004/1/1, SPK004/6 or SPK004/6/6) had a significant effect on retention in drying (P < 0.05). High percentage losses of total carotenoids were, however, correlated with high moisture content and high carotenoid content in fresh sweetpotato roots. After 4 months' storage at room temperature in Uganda, losses of total carotenoid in dried sweetpotato chips were high (about 70%) and this was not dependent on the use of opaque or transparent packaging. CONCLUSION: Losses of carotenoids during storage were considered to be more of a nutritional constraint to the utilisation of dried sweetpotato than losses occurring during drying. The relationship between characteristics of the cultivars and losses of carotenoids during drying should be taken into account in selection of cultivars for processing. Copyright © 2009 Society of Chemical Industry     

Consequences of high transitory airflows generated by segmented pulse-jet cleaning of dust collector filter bags

Baghouse dust collectors are commonly used in industry for removing solid particles from dust-laden gas. Baghouse filter media need to be periodically cleaned in order to remove collected particles from the filter surface. Pulse-jet cleaning is the most commonly used method but the detachment forces involved always affect downstream particle emission adversely. Although it is possible to find information about the mechanisms and the factors that cause particle emission, no link has been made between the distribution of the dirty airflow via the filter elements and the increase in released downstream particles after the bag cleaning.Innovative instrumentation of a pulse-jet-cleaned pilot dust collector allowed measuring the variation in the individual airflows which pass through each filter bag during clogging and cleaning cycles. The way in which segmented pulse-jet cleaning influences total dirty airflow distribution amongst filter elements was investigated. The consequences on bag airflow resistance and downstream particle emission were studied. Filtration cycles can be related to a succession of segmented pulse-jet cleaning, leading to imbalanced bag airflow resistances, and clogging. This in turn leads to compensations between bag resistances as a function of dust-laden individual bag airflow values. Airflow resistance variations are caused by two complementary phenomena: permeation of high transitory airflows on the first bags cleaned and the re-suspension of detached particles after a pulse-jet cleaning.During a cleaning sequence, strong airflow increases on the first cleaned bags are mainly prejudicial to dust collector downstream particle concentration.     

RF VCO tuning using MEMS piezoelectric actuated variable inductors

This paper presents a study on the use of microsystems technology in the design of radio frequency voltage-controlled oscillators. In particular, the application of a micro-electro-mechanical systems (MEMS) based variable inductor for frequency tuning purposes is presented. Although traditionally a MEMS variable inductor is considered as a means to extend the tuning range, in this work it is shown that with correct inductor design it is also possible to facilitate and improve the voltage-controlled oscillator design in terms of phase noise response and power consumption in comparison to a design based on standard capacitive tuning.     

Tetrathiafulvalenium–bromide systems as nanosticks and nanoparticles stabilized by PEDOT

In this communication, we describe the first PEDOT-stabilized TTF-based nanoobjects (PEDOT: poly(3,4-ethylenedioxythiophene)). Two tetrathiafulvalenium–bromide systems, namely TTFBr_0.59 and TTFBr, have been processed as nanosticks and well-dispersed nanoparticles in PEDOT, acting as a stabilizing agent. Nanopowders are studied by various techniques including infrared, Raman, X-ray diffraction, transmission electron microscopy, and transport measurements.     

F2FMI: A toolkit for facilitating face-to-face mobile interaction

The importance of mobile groupware systems resides in the specific tasks that they can perform and other systems cannot. On the one hand, groupware systems allow groups of users to work together providing facilities that single-user systems are unable to offer. On the other hand, unlike stationary systems, mobile systems allow users to work on the move. The intersection of these two technologies offers a new support for activities, such as spontaneous collaboration, that could be facilitated neither by stationary groupware systems nor by mobile single-user systems. However, implementations of this new support are uncommon, probably because of the high development effort required and the seemingly little benefit obtained. In this paper, we aim to reduce this effort by facilitating the development of mobile groupware applications that support such activities. Our proposal to achieve this objective involves the design and implementation of the Face-to-Face Mobile Interaction (F2FMI) toolkit, whose goal is to provide generic and reusable software components required in most cases. We expect this strategy to yield a higher variety of successfully deployed applications, which in turn will demonstrate the benefits of supporting this kind of interactions through mobile devices.