Fluid dynamic properties of a soft shell float with open bottom

ABSTRACT:   A physical model of a soft shell underwater float with an openbottom was constructed and the float was subjected to sinusoidaloscillation in the vertical direction in order to investigate the relationsbetween the characteristic properties of the buoyancy and fluidforces in the movement of the float. No change in the fundamentalperiod of the float was seen in response to the imposed oscillation,but there was a lag in the phase of the float response of up toone-quarter wavelength. Various fluid force factors approached valuesreported for a globular buoy as the float was increasingly filledwith air, but hysteresis was very low. The drag coefficient showedmuch scatter. The dominant factor for control of vertical movementof a soft shell float with open bottom was buoyancy, not fluid resistanceforce. It was concluded that for the purposes of design and controlof these systems, only the float volumetric capacity and air capacitymust be considered.     

Lipid peroxidation-derived hepatotoxic aldehydes, 4-hydroxy-2E-hexenal in smoked fish meat products

ABSTRACT:   Contents of 4-hydroxy-2 E -hexenal (HHE), hepatotoxic aldehydes, in smoked fish meat products (smoked salmon and fish meat sausage) were analyzed. Large differences in these contents between the different samples were observed. Very low levels of HHE were detected in fish meat sausage samples. However, a high level of HHE was observed in one batch of smoked salmon. Changes of HHE contents in yellowtail meat containing cherry and sugi wood vinegar stored at 0°C were also analyzed for 7 days. Malonaldehyde (MA) was also analyzed in these samples as an index of the lipid peroxidation level. After 3 or 7 days of storage, HHE contents in both wood vinegar-added samples were significantly higher, but MA contents were significantly lower than those of the control.     

Gustatory receptor responses in marbled rockfish Sebastiscus marmoratus

Gustatory response of marbled rockfish Sebastiscus marmoratus was recorded from the facial nerve supplying the anterior palate. In amino acids, the lowest threshold was for L -proline at 10⁻⁶–10⁻⁵ M; in ATP-related substances, the value for inosine was approximately 10⁻⁵ M and in organic acids, the value for L -lactic acid was approximately 10⁻⁶ M. An almost complete self-adaptation was observed for stimulants after 5 s application. While a weak solution of L -lactic acid as adapting stimulus depressed the response to it completely, it did not appreciably affect the response to 10-times or more concentrated L -lactic acid solution. In contrast to a weak solution, a moderate solution caused a severe depression of the response to stronger solutions, resulting in a shift of the dose–response curve towards a high concentration range. Time for recovery from adaptation differed depending on chemicals and stimulus duration: for 10⁻⁴ M L -lactic acid, it took about 2.3 and 4.5 s for 1/2 recovery of response magnitude under unadapted condition from the adaptation after 1 s- and 5 s-stimulation, respectively. L -Lactic acid and L -alanine strongly depressed the response to each other, yielding a rightward shift of the dose–response curve. A similar profound cross-adaptation was also observed between inosine and 5'-inosinic acid. The possible role of gustation is discussed.     

Visualization of the respiring bacteria in sediments inhabited by Capitella sp. 1

ABSTRACT:    We used the tetrazolium salt 2-( p -iodophenyl)-3-( p -nitrophenyl)-5-phenyl tetrazolium chloride (INT) to locate sites of active (respiring) bacterial populations in sediments inhabited by the deposit-feeding polychaete Capitella sp. 1. In sediment microcosms, this organism created typical protruding tubes on the sediment surface and burrows from day 1. Within a couple of hours after adding INT into the overlying water, the red color of the reduced form of INT (INT-formazan) became apparent in the water column and on the sediment surface. During the following 24 h, part of the subsurface burrows turned red and the color of formazan intensified with time during incubation. Spatial heterogeneity of the distribution of the formazan deposits along burrows also was recognized. Microscopic observations revealed that the tubes and feces produced by Capitella sp. 1, as well as detrital particles, were the sites of intensive formazan deposition. Observation with higher magnification (up to ×1250) revealed that INT-formazan was present either as bacterial intercellular deposits or as microgranules covering entire bacterial cells. In situ application of INT into a sediment microcosm provides a simple and sensitive way to visualize the impact of burrow structures created by small macrobenthos, such as Capitella , on the distribution of metabolically active bacteria.