Dissolved Oxygen Demand at the Sediment-Water Interface of a Stream: Near-Bed Turbulence and Pore Water Flow Effects

A microbial dissolved oxygen (DO) uptake model was developed for a stream bed, including the effect of turbulence in the flow over the bed and pore water flow in the porous bed. The fine-grained sediment bed has hydraulic conductivities 0.01 ≤ k ≤ 1??cm/s, i.e., sediment particle diameter 0.006 ≤ ds ≤ 0.06??cm. The pore water flow is driven by pressure fluctuations at the sediment-water interface, mostly attributable to near-bed coherent motions in the turbulent boundary layer above the sediment bed. An effective mass transfer coefficient (De) coupled to a pore water flow model was used in the DO transport and DO uptake model. DO flux across the sediment-water interface and into the sediment, i.e., sedimentary oxygen demand (SOD), was related to hydraulic conductivity and microbial oxygen uptake rate in the sediment and shear velocity at the sediment-water interface. Simulated SOD values were validated against experimental data. For hydraulic conductivities of the sediment bed up to k ≈ 0.01??cm/s, the pore water flow effect on SOD was found negligible. Above this threshold, the effective mass (DO) transfer coefficient in the sediment bed (De) becomes larger as the hydraulic conductivity (k) becomes larger as the interstitial flow velocities increase; consequently, DO penetration depth increases with larger hydraulic conductivity of the sediment bed (k), and SOD increases as well. The enhancement of vertical DO transport into the sediment bed is strongest near the sediment-water interface, and rapidly diminishes with depth into the sediment layer. An increase in shear velocity at the sediment-water interface also enhances DO transfer. Shear velocity increases at the sediment-water interface will raise SOD regardless of the maximum oxidation rate if the hydraulic conductivity is above the threshold of k ≈ 1??cm/s. The relationship is nearly linear when U*<0.8??cm/s. At shear velocity U* = 1.6??cm/s, SOD for oxidation rates μ = 1000 and 2000??mg?l-1?d-1 are almost five times larger than those with no pore water flow. When pore water transport of DO is not limiting, SOD is a linear function of oxygen demand rate μ in the sediment when 0 ≤ μ ≤ 200??mg?l-1?d-1.     

Interaction of Fragrance Materials With 2-Hydroxypropyl-beta-Cyclodextrin by Static and Dynamic Head-space Methods

The stability constants for the inclusion of fragrance materials with 2-hydroxypropyl-beta-cyclodextrin (2HP-beta-C yD) in aqueous solution have been determined by the static head-space method. The 1:1 stability constants obtained by this method were in reasonable agreement with the corresponding values in the literature. In addition, the release profiles of fragrance materials from 2HP-beta-CyD aqueous solution were investigated using the dynamic head-space method. It was found that the suppression of the fragrance materials release was dependent on their stability constants.     

Estimation of mechanochemical dechlorination rate of poly(vinyl chlorde)

Poly(vinyl chloride) (PVC) was ground in air with CaO in the presence of quartz powder as a grinding aid by a small-scale planetary ball mill to investigate the relation of the dechlorination rate of PVC with the impact energy of the balls calculated from a computer simulation based on the Discrete Element Method under various conditions. Mechanochemical dechlorination proceeds as the grinding progresses and is improved with an increase in both the mill speed and the amount of balls introduced into the mill. The same trend can be seen in the relation between the specific normal impact energy of the balls and the rotational speed. The relationship between the observed dechlorination rate and the computed normal impact energy of the balls is linear, with a correlation coefficient of 0.965. This relationship can be used to estimate the dechlorination rate of PVC in a large-scale planetary ball mill.     

Pressure-induced changes in the connectin/titin localization in the myofibrils revealed by immunoelectron microscopy

Changes in the connectin/titin localization in post-mortem and pressurized chicken muscles were investigated by immunoelectron microscopy. The anti-connectin monoclonal antibody, 1D11, strongly labeled the sides of thick filaments near the H-zone and weakly labeled the sides of Z-line in the sarcomere prepared immediately after death. With the development of the muscle contraction, the shortening of the sarcomere and the dispersion of the connectin epitope near the H-zone were observed. With the gradual increase of the sarcomere length during further storage, the apparent increase of the width of the epitope in the A-band region stained by the antibody was observed, but the distance from the epitope to M-line remained almost the same length. In the case of high pressure treatment, significant changes in the labeling pattern of the antibody were observed with the increase of the pressure applied. The increase of the distance from the epitope to M-line and dispersion of the epitope were observed in the fiber pressurized at 100 MPa. These phenomena were accelerated with the increase of the pressure applied. The discontinuous dense materials labeled by the antibody at the thick filament near the H-zone were observed in the fiber bundles pressurized at 200 MPa or more. This is probably due to the accumulation of connectin molecule from ordinary location in the sarcomere, because of the pressure-induced destruction of the thick and connectin filaments. In the fiber bundles pressurized at 300 MPa, a significant increase in the distance from the epitope to M-line accompanied with the increase of the sarcomere length was observed. From the results obtained, it was clear that the changes in the location of the connectin epitope induced by the brief exposure to high pressure were drastic in comparison with that in the sarcomere during post-mortem storage.     

Utilization of Lactoferrin as an Iron-Stabilizer for Soybean and Fish Oil

ABSTRACT: We investigated the oxidative stability of soybean oil and fish oil fortified with iron solubilized by lactoferrin (FeLF). Oxidative stability was evaluated by measuring the induction period of the Rancimat test. The induction time of soybean oil added FeCl₃ was decreased; however, that of added FeLF was not. This effect of lactoferrin was also observed in the iron-catalyzed oxidation offish oil at temperatures ranging from 50°C to 120°C, and at concentrations of iron ranging from 0 to 500 ppm. Thus, lactoferrin is considered useful as a natural iron stabilizer for food products containing polyunsaturated fatty acids.     

UV Light-Generated Superhydrophilicity of a Titanium Surface Enhances the Transfer,Diffusion and Adsorption of Osteogenic Factors from a Collagen Sponge

It is a significant challenge for a titanium implant, which is a bio-inert material, to recruit osteogenic factors, such as osteoblasts, proteins and blood effectively when these are contained in a biomaterial. The objective of this study was to examine the effect of ultraviolet (UV)-treatment of titanium on surface wettability and the recruitment of osteogenic factors when they are contained in an atelocollagen sponge. UV treatment of a dental implant made of commercially pure titanium was performed with UV-light for 12 min immediately prior to the experiments. Superhydrophilicity on dental implant surfaces was generated with UV-treatment. The collagen sponge containing blood, osteoblasts, or albumin was directly placed on the dental implant. Untreated implants absorbed only a little blood from the collagen sponge, while the UV-treated implants absorbed blood rapidly and allowed it to spread widely, almost over the entire implant surface. Blood coverage was 3.5 times greater for the UV-treated implants (p < 0.001). Only 6% of the osteoblasts transferred from the collagen sponge to the untreated implants, whereas 16% of the osteoblasts transferred to the UV-treated implants (p < 0.001). In addition, a weight ratio between transferred albumin on the implant and measured albumin adsorbed on the implant was 17.3% in untreated implants and 38.5% in UV-treated implants (p < 0.05). These results indicated that UV treatment converts a titanium surface into a superhydrophilic and bio-active material, which could recruite osteogenic factors even when they were contained in a collagen sponge. The transfer and subsequent diffusion and adsorption efficacy of UV-treated titanium surfaces could be useful for bone formation when titanium surfaces and osteogenic factors are intervened with a biomaterial.     

Damage of yeast cells induced by pulsed light irradiation

DNA damage, such as formation of single strand breaks and pyrimidine dimers was induced in yeast cells after irradiation by pulsed light, which were essentially the same as observed with continuous ultraviolet (UV) light. The UV-induced DNA damage is slightly higher than seen with pulsed light. However, increased concentration of eluted protein and structural change in the irradiated yeast cells were observed only in the case of pulsed light. A difference in the inactivation effect between pulsed light and UV light was found and this suggested cell membrane damage induced by pulsed light irradiation. It is proposed that pulsed light can be used as an effective sterilizing method for the yeast Saccharomyces cerevisiae.     

Molecular cloning and high-level expression in Escherichia coli of fungal alpha-galactosidase from Absidia corymbifera IFO 8084

A cDNA encoding the alpha-galactosidase of Absidia corymbifera IFO 8084 was cloned and sequenced. The cloned DNA has a single open-reading frame consisting of 2190 base pairs, and the deduced amino acid sequence revealed that the mature enzyme consisted of 730 amino acid residues with a molecular mass of 82,712 Da. The native structure of the alpha-galactosidase of A. corymbifera IFO 8084 was determined to be a tetramer. Comparison with amino acid sequences of other alpha-galactosidase showed high homology with sequences of members of family 36. An expression vector, pET32Trx/galalpha, was constructed by introducing the cDNA coding region into a thioredoxin fusion system, pET32-Ek/LIC. The resulting transformant, pET32Trx/galalpha, overproduced the active enzyme as a thioredoxin fused form in the host Escherichia coli. By using His-binding metal affinity chromatography, recombinant alpha-galactosidase was purified to homogeneity in a single step. The purified recombinant fusion alpha-galactosidase showed properties very similar to the native alpha-galactosidase from A. corymbifera IFO 8084.     

Dextran from Leuconostoc mesenteroides augments immunostimulatory effects by the introduction of phosphate groups

The immunological effects of phosphorylated dextran (in which phosphate groups were chemically introduced) on murine splenocytes were examined. When dextran produced by Leuconostoc mesenteroides was phosphorylated by a reaction with polyphosphoric acid in formamide solution for 48 h, the degree of phosphorylation of dextran was maximal. The highest phosphorus content (1.7%, wt/wt) was observed in 40 kDa of dextran. The mitogenic response of murine splenocytes was enhanced by the phosphorylated dextran, but its activity was not related to its molecular weight. A strong response was detected at a concentration of 10 to 500 microg/ml, and the highest activity was obtained 48 h after stimulation. Phosphorylated dextran was characterized as a B-cell-specific mitogen. The expressions of CD86 on CD8alpha- CD11c- and CD8alpha- CD11c+ cells were augmented by phosphorylated dextran. The levels of mRNA expression of gamma interferon and interleukin-10 on murine splenocytes were also increased by the stimulation. These results demonstrate that dextran exerts immunostimulation by the introduction of phosphate groups.