A novel method for controlling LNG pool fires

A novel method for controlling LNG pool fires has been developed. In the proposed method, a layer of granules or blocks of nonflammable, low-density, solid material is situated in bund areas surrounding liquid fuel storage tanks. In the event of a major spill, this material will float on the liquid and by shielding the surface from back radiation, will cause a reduction in the size of the fire if the pool is accidentally ignited.     

Effect of photocatalytic and hydrophobic coatings on brewery surface microorganisms

The aim of this study was to determine whether process hygiene in the beverage industry could be improved by applying new coating techniques to process surfaces. Photocatalytic titanium dioxide (TiO(2)) and hydrophobic coatings applied to stainless steel with or without added antimicrobial compounds were studied in laboratory attachment tests and in a 15-month process study. No clear reductions in numbers of attached microbes were obtained with photocatalytic coatings, except for coatings to which silver had been added. These TiO(2)+Ag coatings reduced microbial coverage in laboratory studies and in some process samples. Hydrophobic coatings reduced the area coverage of microorganisms in 4-h laboratory studies but did not affect colony counts in laboratory or process studies. The surfaces had changed from hydrophobic into hydrophilic during the process study. The coatings did not mechanically fully withstand process conditions; part of the hydrophobic coatings had peeled off, most of the precipitated Ag had dissolved, and some of the TiO(2) coatings were damaged. In conclusion, functional coatings have potential for reducing microbial loads on beverage industry surfaces, but these coatings need further development.     

Electrospun polyurethane fibers for absorption of volatile organic compounds from air

Electrospun polyurethane fibers for removal of volatile organic compounds (VOC) from air with rapid VOC absorption and desorption have been developed. Polyurethanes based on 4,4-methylenebis(phenylisocyanate) (MDI) and aliphatic isophorone diisocyanate as the hard segments and butanediol and tetramethylene glycol as the soft segments were electrospun from their solutions in N,N-dimethylformamide to form micrometer-sized fibers. Although activated carbon possessed a many-fold higher surface area than the polyurethane fiber meshes, the sorption capacity of the polyurethane fibers was found to be similar to that of activated carbon specifically designed for vapor adsorption. Furthermore, in contrast to VOC sorption on activated carbon, where complete regeneration of the adsorbent was not possible, the polyurethane fibers demonstrated a completely reversible absorption and desorption, with desorption obtained by a simple purging with nitrogen at room temperature. The fibers possessed a high affinity toward toluene and chloroform, but aliphatic hexane lacked the necessary strong attractive interactions with the polyurethane chains and therefore was less strongly absorbed. The selectivity of the polyurethane fibers toward different vapors, along with the ease of regeneration, makes them attractive materials for VOC filtration.     

Aldehyde-alcohol reactions catalyzed under mild conditions by chromium(III) terephthalate metal organic framework (MIL-101) and phosphotungstic acid composites

Porous materials based on chromium(III) terephthalate metal organic frameworks (MIL-101) and their composites with phosphotungstic acid (PTA) were studied as heterogeneous acid catalysts in aldehyde-alcohol reactions exemplified by acetaldehyde-phenol (A-P) condensation and dimethylacetal formation from benzaldehyde and methanol (B-M reaction). The MIL-101 was synthesized solvothermically in water, and the MIL101/PTA composite materials were obtained by either impregnation of the already prepared MIL-101 porous matrix with phosphotungstic acid solution or by solvothermic treatment of aqueous mixtures of Cr(NO(3))(3), and terephthalic and phosphotungstic acids. The MIL101/PTA materials appeared to be effective catalysts for both A-P and B-M reactions occurring at room temperature, with half-lives ranging from 0.5 h (A-P) to 1.5-2 h (B-M) and turnover numbers over 600 for A-P and over 2900 for the B-M reaction, respectively. A synergistic effect of the strong acidic moieties (PTA) addition to mildly acidic Br?nsted and Lewis acid cites of the MIL-101 was observed with the MIL101/PTA composites. The ability of the PTA and MIL101/PTA materials to strongly absorb and condense acetaldehyde vapors was discovered, with the MIL101/PTA absorbing over 10-fold its dry weight of acetaldehyde condensate at room temperature. The acetaldehyde was converted rapidly to crotonaldehyde and higher-molecular-weight compounds while in contact with MIL-101 and MIL101/PTA materials. The stability of the MIL-101 and MIL101/PTA catalysts was assessed within four cycles of the 1-day alcohol-aldehyde reactions in terms of the overall catalyst recovery, PTA or Cr content, and reaction rate constants in each cycle. The loss of the catalyst over 4 cycles was approximately 10 wt % for all tested catalysts due to the incomplete recovery and minute dissolution of the components. The reaction rates in all cycles remained unchanged and the catalyst losses stopped after the third cycle. The developed MIL101/PTA composites appear to be feasible for industrial catalytic applications.     

Self-calibration as a tool for high-accuracy determination of silicon solar cell internal quantum efficiency

Light nonuniformity, uncertainty in the illuminated photoactive area, and relative, but not absolute radiometric data for the reference detector, can be the reasons for the inaccuracy or impossibility of solar cell spectral response and quantum efficiency determination. The use of a self-calibration principle permits minimization of the errors caused by the above factors. This principle consists of quite precise calculation of the internal quantum efficiency Q(λ_m) of the test cell at λ_m≈0.8 μm, where the cell response is weakly dependent on emitter and base parameters. Experimentally determined short- and long-wavelength internal quantum efficiencies, Q(0.4) and Q(0.95), respectively, based on relative radiometric data for a reference detector, are used as starting data for the Q(λ_m) calculation. The ratio of the calculated to measured Q(λ_m) values gives the correction factor for shifting the experimental quantum efficiency curve. Computer modeling supports the assumption that uniform deviation of measured Q(λ) can be precisely corrected by calculation. Analysis of the accuracy of the self-calibration method demonstrates very small uncertainties in the corrections of quantum efficiency measurements, attainable for many practical situations. Confirmation of correctness of the proposed method is shown by analysis of the results of spectral response measurements of several solar cells.     

On the Stochastic Sensitivity and Noise-Induced Transitions of a Kaldor-Type Business Cycle Model

In the paper, we consider a Kaldor-type model of the business cycle with external additive and internal parametric disturbances. We study analytically and numerically the probability properties of stochastically forced equilibria and limit cycles via stochastic sensitivity function technique. In particular, we discuss the effects of additive and parametric noises on the economic variables and we detect some stochastic bifurcations such as a P-bifurcation, i.e a phenomenon of noise-induced transition from monostability to bistability. This stochastic bistability causes a new trigger regime in economic dynamics.