Method of determination of the cycle stability of ‘Galisol’ latent heat storage unit substance combinations. Its application to the investigation of the glauber salt storage unit

The evidence of the cycle stability of a latent heat storage unit is an important requirement of its technical application. In this paper an apparatus for investigation of Galisol (GLS) latent heat storage substance combinations is described. The stored heat and the heat transfer power are determined with an uncertainty of ± 5 per cent by means of the applied calibration. The results of the cycle stability of the Glauber salt in its substance combination confirm the stability behaviour of this salt hydrate under the dynamic conditions of the GLS storage unit.     

Texture of cellulose microfibrils of root hair cell walls of Arabidopsis thaliana, Medicago truncatula, and Vicia sativa

Cellulose is the most abundant biopolymer on earth, and has qualities that make it suitable for biofuel. There are new tools for the visualisation of the cellulose synthase complexes in living cells, but those do not show their product, the cellulose microfibrils (CMFs). In this study we report the characteristics of cell wall textures, i.e. the architectures of the CMFs in the wall, of root hairs of Arabidopsis thaliana, Medicago truncatula and Vicia sativa and compare the different techniques we used to study them. Root hairs of these species have a random primary cell wall deposited at the root hair tip, which covers the outside of the growing and fully grown hair. The secondary wall starts between 10 (Arabidopsis) and 40 (Vicia) μm from the hair tip and the CMFs make a small angle, Z as well as S direction, with the long axis of the root hair. CMFs are 3-4 nm wide in thin sections, indicating that single cellulose synthase complexes make them. Thin sections after extraction of cell wall matrix, leaving only the CMFs, reveal the type of wall texture and the orientation and width of CMFs, but CMF density within a lamella cannot be quantified, and CMF length is always underestimated by this technique. Field emission scanning electron microscopy and surface preparations for transmission electron microscopy reveal the type of wall texture and the orientation of individual CMFs. Only when the orientation of CMFs in subsequent deposited lamellae is different, their density per lamella can be determined. It is impossible to measure CMF length with any of the EM techniques.     

Production of a certified reference material for the acrylamidecontent in toasted bread

The need for a certified matrix reference material (CRM) of acrylamide in a food type matrix was emphasized by the competent authorities as a tool to improve comparability, ensuring accuracy and traceability of analytical results. The institute for reference materials and measurements (IRMM) responded to the international request by producing a certified reference material, ERM-BD273, containing endogenous acrylamide in a toasted bread matrix. This work describes the production of the CRM, according to 2 and 3 [ISO Guide 34 (2000). General requirements for the competence of reference materials producers; ISO Guide 35 (2006). Reference materials – General and statistical principles for certification], which comprises the material processing, homogeneity and stability assessment, material characterisation and the acrylamide mass fraction value assignment in toasted bread. Heterogeneity of the material between the vials processed was determined by an in-house validated gas chromatographic methodology involving acrylamide derivatisation and mass spectrometric detection and found to be below 2%. Potential degradation during storage was also investigated and a shelf-life based on this value was established. A collaborative study for material characterisation involved sixteen laboratories applying different analytical methodologies including gas chromatography or high resolution liquid chromatography and isotopic dilution mass spectrometry. The certified value for acrylamide in ERM-BD273, traceable to the international system of units (SI), is (425 ± 29) ng g⁻¹.     

Eel-pout (Zoarces viviparus L.) as a marine bioindicator

Several elements and metal species were analyzed in eel-pout or viviparous blenny (Zoarces viviparus). The analytical data demonstrate that fish muscle is a suitable bioindicator for mercury (Hg) and arsenic (As). About 90% of the total Hg content is present in the fish muscle in the form of methyl mercury. Due to higher concentration levels, the liver is more useful for monitoring Pb and TI. No biomagnification of some trace elements, such as Cd, Ni or Co, were observed in eel-pout. More information is necessary to decide about the use of eel-pout for long-time monitoring programs.     

Hydrodynamic flow in the cytoplasm of plant cells

Plant cells show myosin-driven organelle movement, called cytoplasmic streaming. Soluble molecules, such as metabolites do not move with motor proteins but by diffusion. However, is all of this streaming active motor-driven organelle transport? Our recent simulation study (Houtman et al., 2007) shows that active transport of organelles gives rise to a drag in the cytosol, setting up a hydrodynamic flow, which contributes to a fast distribution of proteins and nutrients in plant cells. Here, we show experimentally that actively transported organelles produce hydrodynamic flow that significantly contributes to the movement of the molecules in the cytosol. We have used fluorescence recovery after photobleaching and show that in tobacco Bright Yellow 2 (BY-2) suspension cells constitutively expressing cytoplasmic green fluorescent protein (GFP), free GFP molecules move faster in cells with active transport of organelles than in cells where this transport has been inhibited with the general myosin inhibitor BDM (2,3-butanedione monoxime). Furthermore, we show that the direction of the GFP movement in the cells with active transport is the same as that of the organelle movement and that the speed of the GFP in the cytosol is proportional to the speed of the organelle movement. In large BY-2 cells with fast cytoplasmic streaming, a GFP molecule reaches the other side of the cell approximately in the similar time frame (about 16 s) as in small BY-2 cells that have slow cytoplasmic streaming. With this, we suggest that hydrodynamic flow is important for efficient transport of cytosolic molecules in large cells. Hydrodynamic flow might also contribute to the movement of larger structures than molecules in the cytoplasm. We show that synthetic lipid (DOPG) vesicles and 'stealth' vesicles with PEG phospholipids moved in the cytoplasm.