Estimate of confidence intervals for geometric mean diameter and geometric standard deviation of lognormal size distribution

Confidence of particle size distribution, which is the size distribution of sample particles selected from a large population with lognormal size distribution, has been studied theoretically. Theoretical equations were derived from the basic formulas commonly used in statistics to estimate confidence intervals for geometric mean diameter and geometric standard deviation. Computer simulation has provided size distribution of sample particles by random sampling in order to confirm the theoretical equations. For both geometric mean diameter and geometric standard deviation, the confidence intervals were calculated so that both values of population were placed approximately in the middle of the intervals. The tendencies for the intervals to decrease with an increase in sample particle number and/or significance level, and with a decrease in geometric standard deviation, were reasonable in statistics. The proposed theoretical equations should be useful for estimating confidence of lognormal size distribution.     

N-acetylpolyethylenimine

Summary This paper describes a blending agent N-acetylpolyethylenimine(AcPEI) for polyamide fiber. Two types of AcPEI were examined; the branched one which was the acetylated product of commercial polyethylenimine(PEI) and the linear one prepared by the ring-opening polymerization of 2-methyl-2-oxazoline. Polyamide fibers(nylon 6) blended with a 2–10 wt % ratio of AcPEI were prepared by the melt-spinning technic. The processability of spinning was very high because and were very compatible with polyamide. In addition, the polyblend fibers obtained displayed good antistatic and dyeing properties, in which containing tertiary amino groups was more effective than. The mechanical properties were also disccussed.     

Analytical studies on local damage to reinforced concrete structures under impact loading by discrete element method

This paper proposes a new analytical approach for assessing local damage to reinforced concrete structures subjected to impact load, by applying the discrete element method (DEM). It first outlines the basis concept and analytical formulation of the DEM. Next, it discusses the results of simulation analyses of concrete material tests, uni-axial compression tests and tensile splitting tests conducted to determine appropriate analytical parameters such as material constants, failure criteria and strength increase factors depending on strain rate. Finally, the adaptability of the DEM to local damage to reinforced concrete structures impacted by rigid and deformable missiles is verified through simulation analyses of various types of impact tests. Furthermore, the various impact response characteristics and failure mechanisms, such as impact forces, penetration behavior, reduction in missile velocity and energy transfer process, which are difficult to obtain experimentally, are analytically evaluated by the DEM.     

Gasification of coals treated with non-aqueous solvents. 1. Liquid ammonia treatment of a bituminous coal

A Japanese bituminous coal was treated with liquid ammonia at temperatures up to 120 °C. Extract was separated from the treated coal by washing with benzene-ethanol mixture. The amount of extract was about 2% in a single treatment at 120 °C and some additional extract was obtained by successive treatments. Particles of the residue had cracks and showed an increase in surface area. The ammonia-treated coal was found highly reactive toward gasification with hydrogen at high temperature when catalysed by nickel.     

Gasification of coals treated with non-aqueous solvents. 4. Reactivity of coals treated with liquid ammonia

Gasification rates of twelve coals treated with liquid ammonia and impregnated with nickel were measured in hydrogen and in steam, and the effects of the ammonia treatment were compared. The treatment was found to promote gasification of most bituminous coals, especially the higher-caking coals. The increases in reactivity relative to untreated specimens were larger for gasification with hydrogen at 1273 K than for those with steam at 1125 K, but the trends with coal rank were similar. From a correlation found between the reactivities and the degree of degradation of the coal particles caused by the ammonia treatment, it was inferred that the treatment affected their pore structure.     

Preparation of higher aliphatic acid esters of wood in an N2O4–DMF cellulose solvent medium

Esterification of wood meal with a series of aliphatic acid anhydrides and acid chlorides in a nonaqueous cellulose solvent, an N₂O₄–DMF solvent, has been studied. The N₂O₄–DMF–pyridine solution used as the reaction medium plays a role in destroying the molecular order of the cellulose within the wood, enabling the cellulose to be uniformly substituted by acyl groups along its chain. These uniformly distributed blocking groups result in the permanent decrystallization of the wood. The acyl blocking groups are best achieved by esterification using acid chlorides in the nonaqueous solvent. Acid chlorides, from caproyl to stearoyl chloride, were found to be much more effective as acylating agents than acid anhydrides, from propionic to caproic anhydride. Although no difference in reactivity can be recognized among the acid chlorides, the reactivity decreases with increase in the number of carbon atoms in the acyl group among the acid anhydrides.     

A simple and rapid method for the determination of lead and cadmium in sediment by graphite furnace atomic absorption spectrometry

A simple and rapid method has been proposed for the routine determination of Pb and Cd in sediment by graphite furnace atomic absorption spectrometry. 0.5 g of dry sediment is digested for 1 h at 140 C with a mixture of 10 ml of HF, 4 ml of HNO₃ and 1 ml of HClO₄ in the Teflon-lined bomb. Pb and Cd in this solution are measured by graphite furnace atomic absorption spectrometry, using an automatic sampling device. Several major elements such as Na and K in the solution give severe interferences in the determination of Pb and Cd, but these interferences can be successfully overcome by the addition of 1% (NH₄)₃PO₄ solution in the same volume of the sample solution for Pb and of 1%, (NH₄)₂SO₄ for Cd as the matrix modifiers to the sample solution respectively. Average contents of Pb and Cd in 36 sediments from 13 reservoirs in remote areas of Japan are 35 and 0.40 ppm, respectively.     

Comparative study on rebound resilience and structures of sodium salts of maleic anhydride-grafted ethylene-co-ethyl acrylates with its analogous polymers

Sodium salts of ethylene-co-ethyl acrylate-g-maleic anhydride show high rebound resilience, the same as those of both saponified ethylene-co-ethyl acrylates and sodium salts of ethylene-co-methacrylic acids at low salt contents. The measurements of thermal and mechanical properties and dynamic viscoelastic behaviors indicate that the sodium salts of ethylene-co-ethyl acrylate-g-maleic anhydride behave like strong ionic bond cross-linkages close to covalent bond cross-linkages in the polymer, differing from the monocarboxylate salts of saponified ethylene-co-ethyl acrylate and the sodium salts of ethylene–methacrylic acid. It is concluded that the strong cross-linking of the dicarboxylate salts of the neutralized ethylene-co-ethyl acrylate-g-maleic anhydride causes the high rebound resilience. © 1994 John Wiley & Sons, Inc.     

Expression of vascular endothelial growth factor gene and its receptor (flt-1) gene in urinary bladder cancer

Factors affecting the ability of Escherichia coli O157:H7 to survive in foods with a(w) less than required for growth have not been fully defined. This study was undertaken to determine the ability of E. coli O157:H7 to survive in a commercial dry infant rice cereal as affected by a(w) (0.35+/-0.04, 0.52+/-0.03 and 0.73+/-0.03), pH (4.0 and 6.8), and temperature (5, 25, 35 and 45 degrees C), and in nine other reduced-a(w) foods. Death of E. coli O157:H7 in cereal was enhanced with increased temperature and decreased pH during a 16- to 24-week storage period. Survival was enhanced at pH 6.8 compared to pH 4.0 in cereal at a(w) 0.34+/-0.04 during initial storage at 5 and 25 degrees C. The effect of temperature (8, 15, 21 and 30 degrees C) on survival and growth of acid-adapted cells of E. coli O157:H7 inoculated into cereal reconstituted with milk or apple juice at two inoculum levels (8.2-12.3 cfu/ml and 82-123 cfu/ml of slurry) was also studied. Growth occurred in cereal reconstituted with milk at all test temperatures and in cereal reconstituted with apple juice at 15, 21 and 30 degrees C. Populations increased by >1 log10 cfu/ml within 3-6 h at 21 and 30 degrees C. Acid-adapted and unadapted cells had similar growth patterns. The effects of temperature and acid adaptation on survival of E. coli O157:H7 in nine commercial foods and food ingredients with pH 4.07-6.49 and a(w) 0.17-0.82 were determined. The pathogen survived in these foods for various lengths of time, depending the storage temperature, with an order of survival of 5 degrees C >21 degrees C >37 degrees C. Survival appeared to be enhanced in foods with highest pH, and acid-adapted cells retained higher viability than unadapted cells in only two of the nine test foods. Of particular importance is the ability of E. coli O157:H7 to survive well in dry foods with a wide range in a(w) and pH, particularly at refrigeration temperature.     

Sorption of flavour compounds in aqueous solution into polyethylene film

Sorption of flavour compounds by the polyethylene (PE) liner of laminated pouches (PET/Al/PE) containing a flavour solution has been studied. The solution contained 43 volatile compounds (each 2 μl litre^?1) in sugar ester solution (3 g litre^?1). The distribution ratios of the flavour compounds for sorption into various PE liners increased with carbon chain length of the flavour compounds from 0.01 to 0.1 for alcohols, from 0.03 to 1.23 for aldehydes, from 0.02 to 5.77 for aliphatic esters and from 0.11 to 11.6 for benzoates. In each series (all straight-chain compounds) the distribution ratios increased about threefold for each methylene group, but in the compounds composed of 11 or more carbon atoms the increment was less or negative. The distribution ratio for a given PE film was proportional to the film thickness. The distribution ratios increased with decreasing crystallinity of the PE film and the results for the films of different crystallinities suggested the existence of an impermeable boundary region surrounding the crystalline material amounting to about 20% of its volume.