A drag chain feeder/conveyor based on standard engineering components

The conveyor consists of a chain being drawn through a pipe. Units handling several tons per hour can be constructed using basic workshop facilities.The operation was demonstrated with a typical mineral (magnetite) and typical grains (mealies and sorghum), using a chain with 25-mm links in pipes with diameters of 25, 38 or 50 mm. Angles ranged from horizontal to 60° and chain speeds from 0.2 to 4 m/s. Through-put varied linearly with chain speed, so that the device has potential also as a controlled solids feeder. The correlations presented enable the essential design parameters of the conveyor to be estimated for materials resembling those tested.The conveyor is intended for small through-puts over distances within 100 m, and when power consumption is not a decisive factor. The rate of wear will depend on the nature of the feed. The suitability of the conveyor for any specific application has to be determined experimentally.     

Laser activation voltammetry: selective removal of reduced forms of methyl viologen deposited on glassy carbon and boron-doped diamond electrodes

The effect of high-intensity laser pulses on the reduction of methyl viologen at glassy carbon electrodes in aqueous solution is investigated using laser activation voltammetry (LAV) under both channel flow and no-flow conditions and compared with the effect of conventional variable-temperature voltammetry. The reduction proceeds in two consecutive one-electron steps, and the neutral two-electron-reduction product of methyl viologen is shown by voltammetry and in situ optical microscopy to form two types of deposits, amorphous and crystalline, on the electrode surface. Laser activation voltammetry using a 10 Hz pulsed Nd-YAG 532 nm laser is shown to remove the deposits from the electrode surface at different laser intensities: the amorphous material is more easily ablated than the crystalline deposit. By conventional variable-temperature voltammetry, it is shown that the two stripping peaks disappear as the temperature is increased. However, with conventional heating, the opposite ease of removal is detected compared to the case of laser activation voltammetry: the stripping response associated with the crystalline material disappears at lower temperatures compared to that for the amorphous material. In the presence of high-intensity laser pulses (>0.17 W cm(-2)), glassy carbon surfaces are damaged and the voltammetric characteristics become poor. It is shown that, by the employment of a thin-film boron-doped diamond electrode grown using a chemical vapor deposition procedure on a tungsten substrate, much higher laser intensities can be applied and well-defined LAV signals can be obtained without deactivation of the electrode.     

Analysis of biostimulated microbial communities from two field experiments reveals temporal and spatial differences in proteome profiles

Stimulated by an acetate-amendment field experiment conducted in 2007, anaerobic microbial populations in the aquifer at the Rifle Integrated Field Research Challenge site in Colorado reduced mobile U(VI) to insoluble U(IV). During this experiment, planktonic biomass was sampled at various time points to quantitatively evaluate proteomes. In 2008, an acetate-amended field experiment was again conducted in a similar manner to the 2007 experiment. As there was no comprehensive metagenome sequence available for use in proteomics analysis, we systematically evaluated 12 different organism genome sequences to generate sets of aggregate genomes, or "pseudo-metagenomes", for supplying relative quantitative peptide and protein identifications. Proteomics results support previous observations of the dominance of Geobacteraceae during biostimulation using acetate as sole electron donor, and revealed a shift from an early stage of iron reduction to a late stage of iron reduction. Additionally, a shift from iron reduction to sulfate reduction was indicated by changes in the contribution of proteome information contributed by different organism genome sequences within the aggregate set. In addition, the comparison of proteome measurements made between the 2007 field experiment and 2008 field experiment revealed differences in proteome profiles. These differences may be the result of alterations in abundance and population structure within the planktonic biomass samples collected for analysis.     

Sequence-specific retention calculator. A family of peptide retention time prediction algorithms in reversed-phase HPLC: applicability to various chromatographic conditions and columns

Separation selectivity of C18 reversed-phase columns from different manufacturers has been compared to evaluate the applicability of our sequence-specific retention calculator (SSRCalc) peptide retention prediction algorithms. Three different versions of SSRCalc are currently in use: 300-A pore size sorbents (TFA as ion-pairing modifier, pH 2), 100 A (TFA, pH 2), and 100 A (pH 10), which have been applied for the separation of randomly chosen mixture of tryptic peptides. The major factor affecting separation selectivity of C18 sorbents was found to be apparent pore size, while differences in end-capping chemistry do not introduce a significant impact. The introduction of embedded polar groups to the C18 functionality increases the retention of peptides containing hydrophobic amino acid residues with polar groups: Tyr and Trp. We also demonstrate that changing the ion-pairing modifier to formic/acetic acid significantly reduces the algorithm's predictive ability, so models developed for different eluent conditions cannot be compared directly to each other.     

Dust and the Sick Building Syndrome

Background. In the Danish Town Hall Study" it has previously been shown that the sick building syndrome is a widespread phenomenon. This has given rise to speculations as to whether biologically active components in dust or whether absorbed organic gases and vapours in the indoor climate may be partly responsible for the sick building syndrome. Therefore, we wished to study whether qualitative conditions in dust, of a physical, chemical, and biological nature, are related to the prevalence of symptoms of the sick building syndrome. Material and methods. The study included 12 town halls in the Copenhagen area. A total of 870 persons participated, 584 women and 286 men. All the participants filled out a questionnaire regarding health and working conditions, and dust samples were collected with a special vacuum cleaner in the working environment of the participants, after which the contents of inorganic and organic particles as well as of human source fragments the (hair, nails, skin) and various fibres were determined. Results. There was a significant correlation (P<0.05) between the prevalence of gram-negative bacteria in the indoor climate dust, and general symptoms (fatigue, heavy-headedness, headache, dizziness, concentration problems) (corr.coeff.=0.73), as well as symptoms from the mucous membranes of the upper respiratory tract (corr.coeff.=0.76). Also, there was a significant relation between the prevalence of particles in the dust and the prevalence of symptoms from the mucous membranes (corr.coeff.=0.81). There was a strong and significant correlation between the total amount of volatile organic components (TVOC) and lack of concentration (corr.coeff. =0.85) and feeling heavy-headed (corr.coeff.=0.72). Macromolecular dust (potentially allergenetic material) was significantly correlated to the prevalence of headache and general malaise/dizziness (corr.coeff.=0.66), while the ability of the dust to liberate histamine was significantly related to the prevalence of general malaise, dizziness (corr.coeff.=0.65) and lack of concentration (corr.coeff. =0.58). Further analyses including a number of potential confounders did not change the results of the above analyses. Conclusion. The results of this study support the hypothesis that qualitative properties of dust are important to the sick building syndrome. The study was based on relatively few buildings, but nevertheless strong correlations were found. In perspective, epidemiological intervention studies should be carried out to investigate whether minimizing the amount of both dust and bacteria in the indoor climate affect the prevalence of sick building syndrome.     

The intravenous halothane test as an experimental method for quantifying stress sensitivity in pigs

The venous blood pH, pCO₂, lactate, pyruvate and haematocrit responses to an intravenous (i/v) infusion of halothane-lipid emulsion were assessed in Pietrain, Pietrain X Norwegian Landrace and Gloucester pigs. Halothane-induced lactacidosis was dose related in the Pietrain (stress sensitive) pigs between 0 and 82 μl halothane kg^?-1, whereas the crossbred and Gloucester pigs did not show any lactacidosis. It is concluded that the i/v halothane test can be used to quantify a stress sensitive pig's reaction to the drug, and that the crossbred pig does not express halothane sensitivity even at a mild level. Carazolol pretreatment in Pietrain pigs increased the halothane-induced lactacidosis, whereas in a separate study carazolol was found to decrease their rate of post-mortem muscle acidification. This indicates that halothane activates a different mechanism from stress when inducing lactacidosis in stress sensitive pigs.