Microfluidic Design of Magnetoresponsive Photonic Microcylinders with Multicompartments

Colloidal photonic structures have been designed to have granular format to use them for paint pigments, encoded carriers, and display pixels. However, conventional approaches only provide spherical or discoid shapes, restricting their applications. Cylindrical granules with fan‐shaped compartments in the cross section are appealing for microcarriers with abundant optical codes and active display pigments for color switching. In this work, a stratified laminar flow of concentrated silica particles is employed, formed in a cylindrical microchannel, to produce cylindrical photonic microparticles with multiple compartments. To accomplish this, a microfluidic device is designed to have one cylindrical main channel connected with four branch channels. Four different photocurable suspensions are independently injected through the branches to form quarter‐cylindrically compartmentalized streams in the main channel. Local ultraviolet irradiation on the main channel polymerizes the suspension, thereby forming cylindrical microparticles with four compartments. In each compartment, silica particles form ordered array which develops particle size–dependent structural color. Therefore, different colors can be incorporated into single microcylinder by employing different sizes of silica particles. Moreover, one of the compartments can be rendered to be magnetoresponsive by embedding aligned magnetic particles, which enables the remote control of microcylinder orientation and therefore the switching of structural colors.     

Influence of modified atmosphere packaging and storage temperature on the sensory and microbiological quality of fresh peeled white asparagus

The sensory and microbiological quality of fresh peeled white asparagus packaged in two different types of P-Plus films and stored at two different temperatures (5 °C and 10 °C) for up to 14 days, was studied. The shelf life limiting alterations at each temperature were evaluated. The best modified atmosphere was determined.At 10 °C, the shelf life was 6 days, the loss of freshness was the main cause of quality loss, as indicated by colour darkening and presence of blotches. Moreover the sensorial acceptance of cooked asparagus was affected, being on the limit.Fresh appearance was maintained better at 5 °C than at 10 °C, being microbial spoilage the main limiting factor. The atmosphere generated with film A (around 7% CO₂ and 15% O₂) inhibited spoilage and maintained the acidity of asparagus better than the atmosphere generated by film B (around 2% CO₂ and 20% O₂). The shelf life of asparagus packaged in film A and stored at 5 °C was 14 days.Mesophiles and enterobacteriaceae counts in asparagus stored at 5 °C were acceptable during 14 days being around 7 log cfu/g. Mesophiles counts were slightly higher in asparagus stored at 10 °C than at 5 °C, while the increase in enterobacteriaceae was clearly higher in asparagus stored at 10 °C.     

High cell density culture of Anabaena variabilis using repeated injections of carbon dioxide for the production of hydrogen

Cyanobacteria have the unique characteristic of using CO₂ in the air as a carbon source and solar energy as an energy source. Reducing equivalents from the fermentation of carbohydrates are used as the primary electron donors in cyanobacteria for the hydrogen producing enzymes. The cells take up CO₂ first to produce cellular substances, which are subsequently used for H₂ production. Since the optimal operating conditions for the CO₂ uptake and H₂ production are different, a two-stage system can be effectively employed to separate these two phases. In this study, for the efficient production of H₂ in the second stage, the conditions for the effective CO₂ uptake and cell growth in the first stage were characterized, and high cell density culture was carried out using repeated injections of CO₂. The specific growth rate and growth yield based on CO₂ decreased with an increase in light intensity or CO₂ concentration. However, the effect of CO₂ concentration on the growth yield was much smaller than that of a light intensity. A CO₂ uptake rate per unit cell decreased linearly with the initial CO₂ concentration in the gas phase. With repeated injections of CO₂, the CO₂ was continuously consumed and the cell concentration reached 3.7 g dry cell/l in 20 days, which is 6.7 times higher than that in a batch culture without further supply of CO₂. The CO₂ injection in the cell growth phase increased not only the cell concentration but also the hydrogen production per gram cell.     

Effects of basic gas diffusion layer components on PEMFC performance with capillary pressure gradient

The gas diffusion layer (GDL) is composed of a substrate and a micro-porous layer (MPL), and is treated with polytetrafluoroethylene (PTFE) to promote water discharge. Additionally, the MPL mainly consists of carbon black and PTFE. In other words, the optimal design of these elements has a dominant effect on the polymer electrolyte membrane fuel cell (PEMFC) performance. For the GDL, it is crucial to prevent water flooding, and the water flux within the GDL is strongly affected by the capillary pressure gradient. In this study, the PEMFC performance was systematically investigated by varying the substrate PTFE content, MPL PTFE content, and MPL carbon loading per unit area. The effects of each experimental variable on the PEMFC performance and especially on the capillary pressure gradient were quantitatively analyzed when the GDLs were manufactured by the doctor blade manufacturing method. The experimental results indicated that as the PTFE content of the anode and cathode GDL increased, the PEMFC performance deteriorated due to the deformation of the porosity and tortuosity of the GDL. Additionally, the PEMFC performance improved as the MPL PTFE content of the cathode GDL increased at low relative humidity (RH), but the PEMFC performance tendency was reversed at high RH. Further, the MPL carbon loading of 2 mg/${\text{cm}}^2$ demonstrated the best performance, and the advantages and disadvantages of the MPL carbon loading were identified. In addition, the effects of each experimental variable on liquid water, water vapor, and gas permeability were investigated.     

High-yield biohydrogen production from biodiesel manufacturing waste by Thermotoga neapolitana

Efficient conversion of glycerol waste from biodiesel manufacturing processes into biohydrogen by the hyperthermophilic eubacterium Thermotoga neapolitana DSM 4359 was investigated. Biohydrogen production by T. neapolitana was examined using the batch cultivation mode in culture medium containing pure glycerol or glycerol waste as the sole substrate. Pre-treated glycerol waste showed higher hydrogen (H₂) production than untreated waste. Nitrogen (N₂) sparging and pH control were successfully implemented to maintain the culture pH and to reduce H₂ partial pressure in the headspace for optimal growth rate and to enhance hydrogen production from the glycerol waste. It was found that hydrogen production increased from 1.24 ± 0.06 to 1.98 ± 0.1 mol-H₂ mol⁻¹ glycerol_consumed by optimising N₂ sparging and pH control. We observed that in medium containing 0.05 M HEPES, with three cycles of N₂ sparging, the H₂ yield increased to 2.73 ± 0.14 mol-H₂ mol⁻¹ glycerol_consumed, which was 2.22-fold higher than the non-N₂ sparged H₂ yield (1.23 ± 0.06 mol-H₂ mol⁻¹ glycerol_consumed).     

Fine‐Grained FSMD Power Gating Considering Power Overhead

As a fine‐grained power gating method for achieving greater power savings, our approach takes advantage of the finite state machine with a datapath (FSMD) characteristic which shows sequential idleness among subcircuits. In an FSMD‐based power gating, while only an active subcircuit is expected to be turned on, more subcircuits should be activated due to the power overhead. To reduce the number of missed opportunities for power savings, we deactivated some of the turned‐on subcircuits by slowing the FSMD down and predicting its behavior. Our microprocessor experiments showed that the power savings are close to the upper bound.     

Design and manufacture of a toroidal-type SMES for combination with real-time digital simulator (RTDS)

The authors designed and manufactured a toroidal-type superconducting magnetic energy storage (SMES) system. The toroidal-type SMES was designed using a 3D CAD program. The toroidal-type magnet consists of 30 double pancake coils (DPCs). The single pancake coils (SPCs), which constitute the double pancake coils, are arranged at an angle of 6° from each other, based on the central axis of the toroidal-type magnet. The cooling method used for the toroidal-type SMES is the conduction cooling type. When the cooling method for the toroidal-type SMES was designed, the two-stage Gifford–McMahon (GM) refrigerator was considered. The Bi-2223 HTS wire, which was made by soldering brass on both sides of the superconductor, is used for the magnet winding. Finally, the authors connected the toroidal-type SMES to a real-time digital simulator (RSCAD/RTDS) to simulate voltage sag compensation in a power utility.     

Design criterion for zero-input asymptotic overflow-stability of recursive digital filters in the presence of quantization

This paper investigates the zero-input stability properties of the exact second-order recursive digital filter having both overflow and quantization non-linearities. Two examples demonstrate the adverse influence of quantization on the overflow-stability property of the filter. Three sets of conditions are presented to ensure asymptotic overflow-stability in the presence of quantization. Using these criteria, various regions in the coefficient plane corresponding to different minimum internal wordlengths required to ensure the non-interaction of overflow and quantization are derived. These results thus form a useful design criterion.This work was supported in part by a Monash Graduate Scholarship (awarded to P.K. Sim) and Telecom Australia under Contract No. 64514.     

Phytochemical evaluation of essential oils, medicinal plants and their preparations

The central objectives of GLAS are (a) to study the associations between pathology--and related impairments and disability--on the one hand, and well-being and utilization of care among older people on the other, and (b) how these associations are affected by person-bound and environmental factors. The present paper describes the main research questions, the design and some preliminary results of GLAS. In addition, an explanatory model for well-being, derived from the theory of social-production functions (spf) is elaborated. Two major conclusions can be drawn from these results. (1) The hypotheses derived from spf are mainly supported by the results of several substudies of GLAS. (2) The cross-sectional analyses showed main effects of psychological attributes--independent of pathology and impairments--on disability and well-being; we hardly found any empirical support for the hypothesized moderating effects of psychological attributes on the associations between these concepts. We conclude with some suggestions for future research.