A one-dimensional model for water quality simulation in medium- and small-sized rivers

While studying water quality in the Tatara river, we realized that the river has various hydraulic and topographic characteristics when flowing through different regions. Because of these specific characteristics, the application of the existing models for simulation of its water quality may not be appropriate due to limitations in the models themselves. Therefore, we developed a mathematical model that is suitable for short-term simulations of water quality in rivers with characteristics similar to the Tatara river. The main foundation of the model is the one-dimensional transport equation established on the basis of the mass conservation law. To solve this equation numerically, it was discretized by the method of finite-difference approximations, and an algorithm has been programmed in Fortran 90. To verify the model, the Tatara river was chosen as a case study. Water temperature, dissolved oxygen, hydraulic parameters in four typical blocks of the river, and meteorological data of the study area, have been observed and used to test the model. By calibrating the model with different series of data collected from the designated blocks, all results have shown a good fit between simulated data and the observed one. Therefore, the model could be a reliable tool for simulating water quality in medium- and small-sized rivers over a short-term period. This research has also indicated the changing tendencies of water temperature and dissolved oxygen in Tatara river in response to different meteorological patterns over a daily 24-h period. Besides, the model could be improved to simulate other water quality variables, which would be studied further.     

Liquefaction of beech wood in various supercritical alcohols

The liquefaction of Japanese beech (Fagus crenata Blume) was studied with various straight-chain alcohols in subcritical and supercritical states using a batch-type reaction vessel to obtain liquid fuel from lignocellulosics. Under the reaction condition of 270°C, beech wood was liquefied to some extent in all alcohols with about 50%–65% insoluble residue left after treatment for 30min. Under the condition of 350°C, however, more than 90% of wood was decomposed and liquefied in all alcohols. Alcohols with longer alkyl chains liquefied lignocellulosics in shorter reaction times. Because many kinds of alcohols, such as methanol and ethanol, can be produced from biomass, 100% biomass-based liquid fuel can be prepared by supercritical alcohol technology when using such bioalcohols. This study was presented in part at the 55th Annual Meeting of the Japan Wood Research Society, Kyoto, Japan, March 16–18, 2005     

Structure and species diversity of subtropical evergreen broad-leaved forest in northern Okinawa Island, Japan

The structure and tree species diversity of a subtropical evergreen broad-leaved forest in northern Okinawa Island, Japan, were studied. Enumeration of the six sampling plots revealed an average density of 5,580 individuals with DBH≧3.0 cm/ha, having an average basal area of 55 m². The large-size trees of DBH≧20 cm contributed 10% of the total individuals, and 49% of the total basal area. The forest showed a high diversity of tree species, which is comparable to some tropical rain forests. A total of 54 over-story species of 24 families and a total of 63 understory species of 26 families were identified in the six sampling plots. Fagaceae and Theaceae were the most important families;Castanopsis sieboldii, Schima wallichii andDistylium racemosum were the most important species. The diversity index and equitability index of species were 4.15 and 0.72 for the overstory plots, and 4.72 and 0.79 for the understory subplots, respectively. The diversity index for the overstory was significantly correlated to the total basal area of trees over 20 cm DBH (p<0.05) and the importance value ofC. sieboldii (p<0.001), while for understory, the diversity index was not correlated to the structural parameters (allp>0.16). The size distribution pattern and age structure indicated differences in regeneration strategies for canopy dominants. In population dynamics of the succession process,C. sieboldii andD. racemosum were self-maintaining types, andS. wallichii was a gap- or opening-dependent type. This study was made possible by support from the Japanese Ministry of Education, Sciences, Sports and Culture, which provided a Monbusho scholarship to X.N. Xu.     

Forestomach developmental failure in an 11-month-old Japanese Black steer with severely retarded growth and chronic ruminal tympany

This study reports findings from the pathological examination of the forestomach of an 11-month-old Japanese Black steer with severely retarded growth (41% of expected weight) and chronic ruminal tympany. The ruminal papillae were weakly formed (0.3–0.5 cm long) and unevenly distributed. The cellulae and cristae reticuli were underdeveloped; the cristae were 0.4–0.7 cm in height and milky white. The keratinized layer in the stratified squamous epithelium was thickened. Ruminal pH was 5.25, and ruminal volatile fatty acid concentration was 11.7 mM. The steer’s severely retarded growth was considered to be caused by malnutrition due to developmental and functional failure of the forestomach.     

Intestinal absorption of p-coumaric and gallic acids in rats after oral administration

Ferulic acid (FA) and p-coumaric acid (CA) are absorbed by the monocarboxylic acid transporter (MCT) in Caco-2 cells, although gallic acid (GA) is not. Therefore, the MCT is selective for certain phenolic acids. Absorption of orally administered CA and GA in rats was studied to obtain serum pharmacokinetic profiles and to investigate their intestinal absorption characteristics in vivo. Rats were administered 100 micromol/kg body weight of CA and GA, and blood was collected from the portal vein and abdominal artery after administration. CA, GA, and their metabolites were quantified with a highly selective and sensitive coulometric detection method using high-performance liquid chromatography-electrochemical detection. Ingested CA was rapidly absorbed in the gastrointestinal tract in an intact form. The serum concentration of intact CA in the portal vein peaked 10 min after dosing (C(max) was 165.7 micromol/L). In contrast, GA was slowly absorbed, with a t(max) for intact GA of 60 min and a C(max) of 0.71 micromol/L. The area under the curve for intact CA and GA was calculated from the serum concentration profile in the portal vein to be 2991.3 and 42.6 micromol min L(-)(1), respectively. The relative bioavailability of CA against GA was about 70. This is the first demonstration that absorption efficiency of CA is much higher than that of GA in vivo. The absorption characteristics of CA are clearly different from those of GA. These findings are in good agreement with the results obtained in vitro using a Caco-2 cell system.     

Effects of urea and trimethylamine-N-oxide on ATPase of requiem shark myofibril and its constituents

ABSTRACT: The effects of trimethylamine- N -oxide (TMAO) on the urea-resistibility of requiem shark myofibrils were investigated, using Ca²⁺- and Mg²⁺-ATPase activities as a parameter. Both activities were hardly changed or activated up to 0.6 M urea. In contrast, the two activities both decreased to less than 50% in the presence of TMAO up to 0.5 M. When measured at a 2 : 1 molar ratio of urea and TMAO, Ca²⁺- and Mg²⁺-ATPase activities were similar to those in the presence of TMAO alone, indicating that TMAO reduced the urea-resistibility of myofibrils. Myosin, the most abundant protein in myofibrils, from requiem shark exhibited the effects of urea and TMAO on its Ca²⁺-ATPase activity, which was primarily similar to those of myofibrils. However, Ca²⁺-ATPase activities in the coexistence of urea and TMAO for actomyosin reconstituted from requiem shark myosin and chicken F-actin were approximately average of those measured independently in the presence of either urea or TMAO alone. Carp myofibrils, reconstituted actomyosin and myosin, which were used as teleost references, all showed a tendency in the effects of urea and TMAO on Ca²⁺-ATPase activities that was similar to those of requiem shark counterparts.