Preparation and evaluation of Fuller's Earth Beads for removal of Cesium from waste streams

This work deals with removal of Cesium (radioactive waste) in dilute aqueous phase by adsorption. Fullers earth was used as an adsorbent. The adsorption capacity of Fullers earth with respect to Cesium was found to be high, 26.3 mg / g of adsorbent.

Systemic recruitment of osteoblastic cells in fracture healing

We hypothesise that following a bone fracture there is systemic recruitment of bone forming cells to a fracture site. A rabbit ulnar osteotomy model was adapted to trace the movement of osteogenic cells. Bone marrow mesenchymal stem cells from 41 NZW rabbits were isolated, culture-expanded and fluorescently labelled. The labelled cells were either re-implanted into the fracture gap (Group A); into a vein (Group B); or into a remote tibial bone marrow cavity 48 h after the osteotomy (Group C) or 4 weeks before the osteotomy was established (Group D), and a control group (Group E) had no labelled cells given. To quantify passive leakage of cells to an injury site, inert beads were also co-delivered in Group B. Samples of the fracture callus tissue and various organs were harvested at discrete sacrifice time-points to trace and quantify the labelled cells. At 3 weeks following osteotomy, the number of labelled cells identified in the callus of Group C, was significantly greater than following IV delivery, Group B, and there was no difference in the number of labelled cells in the callus tissues, between Groups C and A, indicating the labelled bone marrow cells were capable of migrating to the fracture sites from the remote bone marrow cavity. Significantly fewer inert beads than labelled cells were identified in Group B callus, suggesting some of the bone-forming cells were actively recruited and selectively chosen to the fracture site, rather than passively leaked into the circulation and to bone injury site. This investigation supports the hypothesis that some osteoblasts involved in fracture healing were systemically mobilised and recruited to the fracture from remote bone marrow sites. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.

Molecular Computational Elements Encode Large Populations of Small Objects

Since the introduction of molecular computation1, 2, experimental molecular computational elements have grown3, 4, 5 to encompass small-scale integration6, arithmetic7 and games8, among others. However, the need for a practical application has been pressing. Here we present molecular computational identification (MCID), a demonstration that molecular logic and computation can be applied to a widely relevant issue. Examples of populations that need encoding in the microscopic world are cells in diagnostics or beads in combinatorial chemistry (tags). Taking advantage of the small size9 (about 1 nm) and large 'on/off' output ratios of molecular logic gates and using the great variety of logic types, input chemical combinations, switching thresholds and even gate arrays in addition to colours, we produce unique identifiers for members of populations of small polymer beads (about 100 m) used for synthesis of combinatorial libraries10, 11. Many millions of distinguishable tags become available. This method should be extensible to far smaller objects, with the only requirement being a 'wash and watch' protocol12. Our focus on converting molecular science into technology concerning analog sensors13, 14, turns to digital logic devices in the present work.

Nucleation and growth in fluidised hot melt granulation

Fluidised hot melt granulation (FHMG) is a novel technology for granulation process in pharmaceutical industry, which has distinct advantages over other commercial techniques. The aim of this research was to investigate granulation and the effect of process parameters that may affect FHMG process. In this work, ballotini beads were used as the model particles and Lutrol (R) F 68 Poloxamer 188 was used as meltable solid binder. In order to determine the granulation and nucleation mechanism in this co-melt FHMG system, several parameters were investigated, such as binder content, particle size of binder and particle size and hydrophobicity of ballotini. These parameters were correlated to granule size distribution, mean granule size and granule shape. Furthermore, these experimental investigations were designed so that the coalescence model could be applied to the co-melt FHMG system. The analysis indicated that the non-inertial regime extends over a relatively short time period of

Preparation of magnetic cellulose composites using ionic liquids

Cellulose-magnetite composites have been prepared by suspension and dispersion of magnetite particles in a homogenous ionic liquid solution of cellulose, followed by regeneration into water, enabling the preparation of magnetically responsive films, flocs, fibers, or beads. The materials prepared were ferromagnetic, with a small superparamagnetic response, characteristic of the initial magnetite added. X-ray diffraction data indicated that the magnetite particles were chemically unaltered after encapsulation with an average particle size of approximately 25 nm.

Ionic liquid-reconstituted cellulose composites as solid support matrices for biocatalyst immobilization

Preparation of cellulose-polyamine composite films and beads, which provide high loading of primary amines on the surface allowing direct one-step bioconjugation of active species, is reported using an ionic liquid (IL) dissolution and regeneration process. Films and bead architectures were prepared and used as immobilization supports for laccase as a model system demonstrating the applicability of this approach. Performance of these materials, compared to commercially available products, has been assessed using millimeter-sized beads of the composites and the lipase-catalyzed transesterification of ethyl butyrate.

Production of bioactive cellulose films reconstituted from ionic liquids

A new method for introducing enzymes into cellulosic matrixes which can be formed into membranes, films, or beads has been developed using a cellulose-in-ionic-liquid dissolution and regeneration process. Initial results on the formation of thin cellulose films incorporating dispersed laccase indicate that active enzyme-encapsulated films can be prepared using this methodology and that precoating the enzyme with a second. hydrophobic ionic liquid prior to dispersion in the cellulose/ionic liquid solution can provide an increase in enzyme activity relative to that of untreated films, presumably by providing a stabilizing microenvironment for the enzyme.

Monitoring microbial sulfate reduction in porous media using multi-purpose electrodes

There is growing interest in the application of electrode-based measurements for monitoring microbial processes in the Earth using biogeophysical methods. In this study, reactive electrode measurements were combined to electrical geophysical measurements during microbial sulfate reduction occurring in a column of silica beads saturated with natural river water. Electrodic potential (EP), self potential (SP) and complex conductivity signals were recorded using a dual electrode design (Ag/AgCl metal as sensing/EP electrode, Ag/AgCl metal in KCl gel as reference/SP electrode). Open-circuit potentials, representing the tendency for electrochemical reactions to occur on the electrode surfaces, were recorded between sensing/EP electrode and reference/SP electrode and showed significant spatiotemporal variability associated with microbial activity. The dual electrode design isolates the microbial driven sulfide reactions to the sensing electrode and permits removal of any SP signal from the EP measurement. Based on the known sensitivity of a Ag electrode to dissolved sulfide, we interpret EP signals exceeding 550 mV recorded in this experiment in terms of bisulfide (HS-) concentration near multiple sensing electrodes. Complex conductivity measurements capture an imaginary conductivity (s?) signal interpreted as the response of microbial growth and biomass formation in the column. Our results suggest that the implementation of multipurpose electrodes, combining reactive measurements with electrical geophysical measurements, could improve efforts to monitor microbial processes in the Earth using electrodes.

Clean preparation of nanoparticulate metals in porous supports: a supercritical route

Here we present the synthesis of nanometre sized silver particles which have been trapped within porous substrates; poly( styrene-divinylbenzene) beads and silica aerogels. This is the first time that supercritical carbon dioxide has been used to impregnate such porous materials with silver coordination complexes. In this paper we demonstrate that control over the resultant nanoparticles with respect to size, loading and distribution in the support material has been achieved by simple choice of the precursor complex. The solubility of the precursor complexes in the supercritical solvent is shown to be one of the key parameters in determining the size of the nanoparticles, their distribution and their homogeneity within the support matrix. Moreover, we demonstrate that the same methodology can be applied to two very different substrate materials. In the particular case of aerogels, conventional organic solvents could not be used to prepare nanoparticles because the surface tension of the solvent would lead to fracturing of the aerogel structure.

Maximising capture efficiency and specificity of magnetic separation for Mycobacterium avium subsp. paratuberculosis cells

In order to introduce specificity for Mycobacterium avium subsp. paratuberculosis prior to a phage amplification assay, various magnetic-separation approaches, involving either antibodies or peptides, were evaluated in terms of the efficiency of capture (expressed as a percentage) of M. avium subsp. paratuberculosis cells and the percentage of nonspecific binding by other Mycobacterium spp. A 50:50 mixture of MyOne Tosylactivated Dynabeads coated with the chemically synthesized M. avium subsp. paratuberculosis-specific peptides biotinylated aMp3 and biotinylated aMptD (i.e., peptide-mediated magnetic separation [PMS]) proved to be the best magnetic-separation approach for achieving 85 to 100% capture of M. avium subsp. paratuberculosis and minimal (<1%) nonspecific recovery of other Mycobacterium spp. (particularly if beads were blocked with 1% skim milk before use) from broth samples containing 103 to 104 CFU/ml. When PMS was coupled with a recently optimized phage amplification assay and used to detect M. avium subsp. paratuberculosis in 50-ml volumes of spiked milk, the mean 50% limit of detection (LOD50) was 14.4 PFU/50 ml of milk (equivalent to 0.3 PFU/ml). This PMS-phage assay represents a novel, rapid method for the detection and enumeration of viable M. avium subsp. paratuberculosis organisms in milk, and potentially other sample matrices, with results available within 48 h.

Development of a recombinant Fab-fragment based electrochemical immunosensor for deoxynivalenol detection in food samples

A reliable and cost-effective electrochemical method for the detection of deoxynivalenol (DON) in cereals and cereal-based food samples based on the use of a novel anti-DON Fab fragment is presented. The analytical system employed, Enzyme-Linked-Immunomagnetic-Electrochemical (ELIME) assay, is based on the use of immunomagnetic beads (IMBs) coupled with eight magnetized screen-printed electrodes (8-mScPEs) as electrochemical transducers.