Succession of a microbial community during stable operation of a semi-continuous garbage-decomposing system

The microbial community in a garbage-decomposing system was analyzed using denaturing gradient gel electrophoresis (DGGE) on the basis of 16S rDNA. The system treated 1 kg of garbage everyday for two months at ambient temperature with almost constant decomposition efficiency, although a transient pH increase occurred. Succession of the banding pattern of the DGGE profile suggested that the bacterial community was not directly affected by the continuous addition of non-sterilized garbage into the open system, but changed with the fluctuation of pH. These resistance and resilience characteristics of the community structure may be effective to keep the decomposition efficiency stable. The analyses of the DNA sequences from the DGGE bands suggested the existence of uncultured or novel bacteria as well as Lactobacillus sp., Corynebacterium spp., Enterococcus spp., and Staphylococcus sp. A specific PCR detection was performed to evaluate the existence of Escherichia coli within the community. E. coli 16S rDNAs were not detected from the decomposing system.     

Synthesis and biodegradation of copolyesterether of copoly(succinic anhydride/ethylene oxide) with triblock copolymer of poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene)

The thermal properties and biodegradability of the block copolyesterethers with copoly[succinic anhydride (SA)/ethylene oxide (EO)], synthesized by ring-opening copolymerization as a hard segment and the triblock copolyethers of poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) (PN) as a soft segment, were studied. The block copolyesterethers synthesized from higher than 8000 number-average molecular weight (M_n) of copoly(SA/EO)s showed a microphase separation structure as determined by the thermal properties [melting point (T_m) and glass transition (T_g)], at any polymer composition [EO/propylene oxide (PO)] or the determination of M_n of PN. A decrease in the M_n of copoly(SA/EO) or an increase in PO content in PN resulted in depression of heats of fusion (ΔH) of these block copolyesterethers. The enzymatic degradation of the block copolyesterethers by the lipase from Rhizopus arrhizus showed a substantial increase with a decrease in their ΔH, whereas it was depressed with an increase in the M_n of polyoxyethylene or polyoxypropylene segment in the block copolyesterethers. The block copolyesterethers were degraded by microorganisms in activated sludge. The biodegradability of the block copolyesterethers showed a pronounced drop, with an increase in the polyoxyethylene chain length or polyoxypropylene content in PN. The polycondensation was also conducted without a catalyst at 190°C, similarly, to the reaction catalyzed with Ti[OCH(CH₃)₂]₄ at 170°C. The effect of the residual titanium on the biodegradability of the block copolyesterethers was negligible. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 303–313, 1998     

Occurrence of cholesterol as a major sterol component in leaf surface lipids

Cholesterol has been detected as one of the major sterols in the surface lipids of higher plant leaves. It was widely distributed among the plant leaves of various species as a common main sterol component with a few exceptions. The content of cholesterol amounted to 71.5% of the total sterols in the surface lipids of rape leaves. However, the proportion of cholesterol in the intracellular lipids of rape leaves was lower than that in the surface lipids, and the seed lipids contained only a trace amount of cholesterol, as reported in the literature. In the leaf surface lipids examined, a minor amount of cholestanol associated with cholesterol often was detected by capillary gas chromatography and gas chromatography-mass spectrometry. The related analysis for the surface lipids of fruits showed that cholesterol was one of the major component sterols also in those lipids of several species.     

Effect of primary structure on permselectivity of ultrathin semipermeable polybenzimidazole membrane

A series of polybenzimidazoles (PBIs) with different main chains and sulfonated PBI were successfully synthesized from the corresponding dicarboxylic acids and 3,3'‐diaminobenzidine for the formation of ultrathin, single‐component, and semipermeable membranes. Furthermore, the covalently crosslinked PBI membrane was prepared by the reaction of sulfonated PBI with divinyl sulfone. Their water transport properties were evaluated under a reverse osmosis mode and compared with the primary structure based on the water permeability (A) and salt permeability (B) values normalized by the membrane thickness. It was found that the A and B values of the PBIs were improved with increasing the weight ratio of the imidazole rings per repeating unit, the introduction of sulfonate group as the hydrophilic group to the PBI was an effective way to enhance the A value, and the crosslinked structure enhanced the salt rejection rate (R) value while maintaining the water flux. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41531.     

Outward propagation velocity and acceleration characteristics in hydrogen-air deflagration

Propagation characteristics of hydrogen-air deflagration need to be understood for an accurate risk assessment. Especially, flame propagation velocity is one of the most important factors. Propagation velocity of outwardly propagating flame has been estimated from burning velocity of a flat flame considering influence of thermal expansion at a flame front; however, this conventional method is not enough to estimate an actual propagation velocity because flame propagation is accelerated owing to cellular flame front caused by intrinsic instability in hydrogen-air deflagration. Therefore, it is important to understand the dynamic propagation characteristics of hydrogen-air deflagration. We performed explosion tests in a closed chamber which has 300 mm diameter windows and observed flame propagation phenomena by using Schlieren photography. In the explosion experiments, hydrogen-air mixtures were ignited at atmospheric pressure and room temperature and in the range of equivalence ratio from 0.2 to 1.0. Analyzing the obtained Schlieren images, flame radius and flame propagation velocity were measured. As the result, cellular flame fronts formed and flame propagations of hydrogen–air mixture were accelerated at the all equivalence ratios. In the case of equivalent ratio φ = 0.2, a flame floated up and could not propagate downward because the influence of buoyancy exceeded a laminar burning velocity. Based upon these propagation characteristics, a favorable estimation method of flame propagation velocity including influence of flame acceleration was proposed. Moreover, the influence of intrinsic instability on propagation characteristics was elucidated.     

Study of biodegradability of poly(δ-valerolactone-co-L-lactide)s

The biodegradability of poly(δ-valerolactone-co-L -lactide)s was studied both with enzymatic (lipase from Rhizopus arrhizus) and nonenzymatic hydrolyses. The hydrolyzability was evaluated by recording the amount of the hydrolyzed water-soluble products. The enzymatic hydrolysis was considerably affected by copolymer composition. The copolyester, the most susceptible to enzymatic hydrolysis, was the one containing a 90 mol % δ-valerolactone unit. The copolymers were also nonenzymatically hydrolyzed at 70°C. The results were similar to those of enzymatic hydrolysis, confirming the influence of copolymer composition on the hydrolyzability. However, the L -lactide rich copolymers were more susceptible to hydrolysis. These results suggest that poly(δ-valerolactone) is easily degraded by lipase, whereas poly(L -lactide) is degraded through simple hydrolysis. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 741–748, 1997     

Development of natural killer cells, B lymphocytes, macrophages, and mast cells from single hematopoietic progenitors in culture of murine fetal liver cells

We have recently established a clonal culture system that supports the growth of immature natural killer (NK) cells from murine fetal thymocytes. We now describe a culture system for mixed NK cell colony formation from single lymphohematopoietic progenitors. When Sca-1+c-kit+ fetal liver cells were cultured in methylcellulose media with interleukin (IL)-2, IL-7, IL-11, and steel factor (SF), we found mixed colonies consisting of diffuse small round cells characteristic of immature NK cells and other types of cells. The single cell origin of the mixed colonies was established by micromanipulation. Individual mixed colonies derived from single cells were characterized by flow cytometric analysis and May-Grünwald Giemsa staining. All mixed colonies contained Thy-1+B220- cells, which can differentiate to mature NK cells in fetal thymus organ culture. Most of the colonies contained B220+ B-lineage cells and macrophages, and some contained mast cells. IL-1alpha and IL-3, which have previously been shown to inhibit the T- and B-cell potentials of blast colonies, suppressed the formation of mixed NK cell colonies. The clonal culture assay presented here may be useful in analysis of the developmental pathway and commitment of NK cells from multipotential progenitors.     

Stabilisation in bacillus stearothermophilus of a recombinant plasmid carrying the homologous α-amylase gene

The phenotypic stability of the recombinant plasmid pAT9 (11.5 MD), which contained the cloned α-amylase gene from B. stearothermophilus, was studied in batch and continuous culture. Irrespective of the type of culture (batch or continuous; or using glucose or maltose as carbon source), deletion plasmids of the phenotype Km^rAmy^? the same size (7.3 MD) emerged with time. DNA sequencing analysis and Southern hybridization of a region adjacent to both ends of the pAT9 HindIII fragment containing the α-amylase gene showed that almost the entire part of the HindIII fragment was lost. Homology between fragments contiguous to the pAT9 HindIII terminals allowed exclusion of a fragment that did not encode the α-amylase gene and a new recombinant plasmid, pATHP9 (Km^rAmy⁺; 7.5 MD), was constructed which had enhanced phenotypic stability in B. stearothermophilus.