Comparative structural analyses of purified glycogen particles from rat liver, human skeletal muscle and commercial preparations

Glycogen is a cellular energy store that is crucial for whole body energy metabolism, metabolic regulation and exercise performance. To understand glycogen structure we have purified glycogen particles from rat liver and human skeletal muscle tissues and compared their biophysical properties with those found in commercial glycogen preparations. Ultrastructural analysis of commercial liver glycogens fails to reveal the classical α-rosette structure but small irregularly shaped particles. In contrast, commercial slipper limpet glycogen consists of β-particles with similar branching and chain lengths to purified rat liver glycogen together with a tendency to form small α-particles, and suggest it should be used as a source of glycogen for all future studies requiring a substitute for mammalian liver glycogen.

Performance of suspended and attached growth MBR systems in treating high strength synthetic wastewater

The performance of laboratory-scale attached growth (AG) and suspended growth (SG) membrane bioreactors (MBRs) was evaluated in treating synthetic wastewater simulating high strength domestic wastewater. This study investigated the influence of sponge suspended carriers in AG-MBR system, occupying 15% reactor volume, on the removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP), and compared it to that of SG-MBR. Results showed that the removal efficiencies of COD, TN and TP in AG-MBR were 98%, 89% and 58%, respectively as compared to 98%, 74% and 38%, respectively in SG-MBR. Improved TN removal in AG-MBR systems was primarily based on simultaneous nitrification and denitrification (SND) process. These results infer that the presence of small bio-particles having higher microbial activity and the growth of complex biomass captured within the suspended sponge carriers resulted in improved TN and TP removal in AG-MBR.

Release of allergens in respirable aerosols : a link between grass pollen and asthma

Background: Asthma incidence has long been linked to pollen, even though pollen grains are too large to penetrate into the airways where asthmatic responses originate. Pollen allergens found in small, respirable particles have been implicated in a number of asthma epidemics, particularly ones following rainfall or thunderstorms.

Objective: The aim of this study was to determine how pollen allergens form the respirable aerosols necessary for triggering asthma.

Methods: Flowering grasses were humidified and then dried in a controlled-environment chamber connected to a cascade impactor and an aerosol particle counter. Particles shed from the flowers were analyzed with high-resolution microscopy and immunolabeled with rabbit anti-Phl p 1 antibody, which is specific for group 1 pollen allergens.

Results: Contrary to what has been reported in other published accounts, most of the pollen in this investigation remained on the open anthers of wind pollinated plants unless disturbed—eg, by wind. Increasing humidity caused anthers to close. After a cycle of wetting and drying followed by wind disturbance, grasses flowering within a chamber produced an aerosol of particles that were collected in a cascade impactor. These particles consisted of fragmented pollen cytoplasm in the size range 0.12 to 4.67 μm; they were loaded with group 1 allergens.

Conclusion: Here we provide the first direct observations of the release of grass pollen allergens as respirable aerosols. They can emanate directly from the flower after a moisture-drying cycle. This could explain asthmatic responses associated with grass pollination, particularly after moist weather conditions.

Plane wave scattering by a spherical di-electric particle in motion : a relativistic extension of the Mie theory

Light scattering from small spherical particles has applications in a vast number of disciplines including astrophysics, meteorology optics and particle sizing. Mie theory provides an exact analytical characterization of plane wave scattering from spherical dielectric objects. There exist many variants of the Mie theory where fundamental assumptions of the theory has been relaxed to make generalizations. Notable such extensions are generalized Mie theory where plane waves are replaced by optical beams, scattering from lossy particles, scattering from layered particles or shells and scattering of partially coherent (non-classical) light. However, no work has yet been reported in the literature on modifications required to account for scattering when the particle or the source is in motion relative to each other. This is an important problem where many applications can be found in disciplines involving moving particle size characterization. In this paper we propose a novel approach, using special relativity, to address this problem by extending the standard Mie theory for scattering by a particle in motion with a constant speed, which may be very low, moderate or comparable to the speed of light. The proposed technique involves transforming the scattering problem to a reference frame co-moving with the particle, then applying the Mie theory in that frame and transforming the scattered field back to the reference frame of the observer.

Effect of magnetic treatment on microstructure and cycle performance of LiFePO4/C cathode material

LiFePO4/C composite was prepared by hydrothermal synthesis along with a magnetic treatment method. The LiFePO4/C composite synthesized without magnetic treatment is an integrated rhombic shape crystal, whereas the LiFePO4/C material synthesized with magnetic treatment presents a rhombus shape which is self-assembled by a number of small crystal particles with an average size of about 100 nms. The capacity retention for the LiFePO4/C cathode material synthesized without magnetic treatment is only 77% after 30 charge-discharge cycles at 0.2 C, but the LiFePO4/C composite synthesized with magnetic treatment has a capacity retention of 100% after 100 charge-discharge cycles at 1 C and 5 C. It suggests that magnetic treatment can remove Fe3+ cations effectively during the preparation process and enhance the cycle performance of the LiFePO4/C material.

Dielectrophoretically assembled particles : feasibility for optofluidic systems

This work presents the dielectrophoretic manipulation of sub-micron particles suspended in water and the investigation of their optical responses using a microfluidic system. The particles are made of silica and have different diameters of 600, 450, and 250 nm. Experiments show a very interesting feature of the curved microelectrodes, in which the particles are pushed toward or away from the microchannel centerline depending on their levitation heights, which is further analyzed by numerical simulations. In doing so, applying an AC signal of 12 V_p-p and 5 MHz across the microelectrodes along with a flow rate of 1 μl/min within the microchannel leads to the formation of a tunable band of particles along the centerline. Experiments show that the 250 nm particles guide the longitudinal light along the microchannel due to their small scattering. This arrangement is employed to study the feasibility of developing an optofluidic system, which can be potentially used for the formation of particles-core/liquid-cladding optical waveguides.

Major grass pollen allergen Lol p 1 binds to diesel exhaust particles : implications for asthma and air pollution

Background Grass pollen allergens are known to be present in the atmosphere in a range of particle sizes from whole pollen grains (approx. 20 to 55 μim in diameter) to smaller size fractions < 2.5 μ (fine particles, PM2.5). These latter particles are within the respirable range and include allergen-containing starch granules released from within the grains into the atmosphere when grass pollen ruptures in rainfall and are associated with epidemics of thunderstorm asthma during the grass pollen season. The question arises whether grass pollen allergens can interact with other sources of fine particles, particularly those present during episodes of air pollution.

Objective We propose the hypothesis that free grass pollen allergen molecules, derived from dead or burst grains and dispersed in microdroplets of water in aerosols, can bind to fine particles in polluted air.

Methods We used diesel exhaust carbon particles (DECP) derived from the exhaust of a stationary diesel engine, natural highly purified Lol p 1, immunogold labelling with specific monoclonal antibodies and a high voltage transmission electron -microscopic imaging technique

Results DECP are visualized as small carbon spheres, each 30–60 nm in diameter, forming fractal aggregates about 1–2μ in diameter. Here we test our hypothesis and show by in vitro experiments that the major grass pollen allergen, Lol p I. binds to one defined class of fine particles, DECP.

Conclusion DECP are in the respirable size range, can bind to the major grass pollen allergen Lol p I under in vitro conditions and represent a possible mechanism by which allergens can become concentrated in polluted air and thus trigger attacks of asthma.

Control of partial coalescence of self-assembled metal nano-particles across lyotropic liquid crystals templates towards long range meso-porous metal frameworks design

The formation of purely metallic meso-porous metal thin films by partial interface coalescence of self-assembled metal nano-particles across aqueous solutions of Pluronics triblock lyotropic liquid crystals is demonstrated for the first time. Small angle X-ray scattering was used to study the influence of the thin film composition and processing conditions on the ordered structures. The structural characteristics of the meso-structures formed demonstrated to primarily rely on the lyotropic liquid crystal properties while the nature of the metal nano-particles used as well as the their diameters were found to affect the ordered structure formation. The impact of the annealing temperature on the nano-particle coalescence and efficiency at removing the templating lyotropic liquid crystals was also analysed. It is demonstrated that the lyotropic liquid crystal is rendered slightly less thermally stable, upon mixing with metal nano-particles and that low annealing temperatures are sufficient to form purely metallic frameworks with average pore size distributions smaller than 500 nm and porosity around 45% with potential application in sensing, catalysis, nanoscale heat exchange, and molecular separation.