Mineralogical and chemical characterization of some vermiculites from the mozambique belt of tanzania for agricultural use

Vermiculite minerals are locally available in the Mozambique Belt of Tanzania but are not currently commercially exploited. In part this may be due to lack of any precise characterization. This study was carried out as a first step to assess the suitability of these vermiculites for crop production by characterization of their mineralogical and chemical compositions. X-ray diffraction and scanning electron microscopy combined with an energydispersive X-ray system were used to establish the mineralogy. Electron microprobe analysis and inductively coupled plasma-mass spectrometry were used to study the chemical compositions and to identify any possible issues related to chemical composition that might affect their use if applied as soil conditioners. The samples were characterized as vermiculites and hydrobiotites with a wide variety of accessory minerals. Accessory minerals that might be of some concern are galena, fibrous amphiboles and sepiolite. The total levels of Ni in all vermiculites, and Cr in some, were also found to be high relative to common European standards and this might limit their potential as soil conditioners. It is clear that a field assessment of the bioavailability of various elements would be necessary before decisions relating to potential agricultural use could be made. © 2009 The Mineralogical Society.

Advanced materials for recognition and capture of whole cells and microorganisms

Selective cell recognition and capture has recently attracted significant interest due to its potential importance for clinical, diagnostic, environmental, and security applications. Current methods for cell isolation from complex samples are largely dependent on cell size and density, with limited application scope as many of the target cells do not exhibit appreciable differences in this respect. The most recent and forthcoming developments in the area of selective recognition and capture of whole cells, based on natural receptors, as well as synthetic materials utilising physical and chemical properties of the target cell or microorganism, are highlighted. Particular focus is given to the development of cell complementary surfaces using the cells themselves as templating agents, by means of molecular imprinting, and their combination with sensing platforms for rapid cell detection in complex media. The benefits and challenges of each approach are discussed and a perspective of the future of this research area is given.

TRP Channels and calcium signalling in dental pulp stem cells

Introduction: Ca2+ ion is an important intracellular messenger essential for the regulation of various cellular functions including proliferation, differentiation and apoptosis. Transient Receptor Potential (TRP) channels are calcium permeable cationic channels that play important role in regulation of free intracellular calcium ([Ca2+]i) in response to thermal, physical and chemical stimuli. Ca2+ signalling in human dental pulp stem cells (hDPSCs) and the ion channels regulating Ca2+ are largely not known. Objectives: Investigate changes in [Ca2+]i and determine the ion channels that regulate calcium signalling in hDPSCs. Methods: DPSCs were derived from immature third molars and cells less than passage 6 were used in all the experiments. Changes in [Ca2+]i were studied with Fura2 calcium imaging. RNA was extracted from DPSCs and a panel of TRP channel gene expression was determined by qPCR employing custom designed FAM TRP specific primers and probes (Roche, UK) and the Light Cycler 480 Probes Master (Roche). Results: hDPSCs express gene transcripts for all TRP families including TRPV1, V2, V4, TRPA1, TRPC3, TRPC5, TRPC6, TRPM3, TRPM7 and TRPP2. Stimulation of cells with appropriate TRP channel agonist induced increase in [Ca2+]i and similar responses were obtained when cell were mechanically stimulated by membrane stretch with application of hypotonic solution. Conclusion: TRP channels mediate calcium signalling in hDPSCs that merit further investigation.