• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.920-926
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• 1998

To investigate the effects of yellow loess on the microbial community after applying into C. polykrikoides as a red tide centrol method during decomposition process, we conducted this study using microcosm experiments, which consisted of sediment collected from Jinhae and Masan bay. The composition, number of bacteria and respiratory electron transport system activity (ETSA) were analyzed. The number of heterotrophic bacteria examined in the samples of both stations reached maximum value within 12 hrs with $10^7$ cells/dry g, independent with the yellow loess applied. In addition, a differenee in the variation of heterotrophic bacterial composition was not observed by adding the yellow loess, and Vibrio spp. always appeared during the culture periods, However, in day 8 culture, the sulfate reducing bacteria was $3.8\times10^7$ cells/dry g in Masan bay and $5.5\times10^6$ cells/dry g in Jinhae bay samples without yellow loess, and these were 120, 350 fold-and 160, 420 fold-increased when yellow loess was added (1 : 1, 1 : 2). The average ETSA was 6.8$\~$7.6 $\mu$g formazan $h^{-1}$ dry $g^{-1}$ independently with yellow loess in aerobic condition for both samples, but activity was decreased by addition of yellow loess in anaerobic. Thus the addition of yellow loess to marine sediment seems to have an effect to inhibit the anaerobic decomposition process and growth of sulfate reducing bacteria which lead to the bad condition of marine environments.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.428-433
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• 2013

Heterogenous samples of locust bean gum (galactomannan) were prepared into homogeneous substances. Locust bean gum was fractioned using ammonium sulfate (14.11-23.08%, w/w). The intrinsic viscosity was obtained by extrapolating reduced viscosity versus concentration by using an Ubbelohde viscometer. The ranges of intrinsic viscosity for fractions that not included protein (F3-F6) and fractions that included protein (F1-F2) were 9.89-8.10 and 8.44-4.59, respectively. Values for Huggins' coefficient (k'), which depends on physical interactions, were 0.46-0.78. Increasing ammonium sulfate concentration was associated with a weak trend towards lower molecular weight and intrinsic viscosity by size-exclusion chromatography (SEC): $M_w$ ranged from 674 to 617 kg/mol and [${\eta}$] from 9.80 to 8.10 dL/g between F3 and F6. The evaluations of those fractions by using SEC and the Ubbelohde viscometer produced very similar values, as predicted. We verified the application of a gradient of ammonium sulfate to precipitate locust bean gum into fractions of different molecular size and show structural variations.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.6-10
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• 2006

The sulphur spinel $FeCr_{2-x}M_xS_4$(M=Ga, In) have been studied with Mossbauer spectroscopy, x-ray diffraction (XRD), and vibrating sample magnetometer. The XRB patterns for samples $FeCr_{2-x}M_xS_4$(M=Ga, In: x=0.1, 0.3) reveal a single phase, which the Ga and In ions are partially occupied to the tetrahedral (A) site. The Neel temperature for the Ga substituted samples increases from 180 to 188 K, with increase from x=0.1 to 0.3. While, it decreases from 173 to 160 K, for the In substituted samples of the x=0.1 and 0.3, respectively. The Mossbauer spectra were collected from 4.2 K to room temperature. We have analyzed the Mossbauer spectra using eight Lorentzian lines fitting method for the $FeCr_{2-x}In_xS_4$(x=0.1) at 4.2 K, yielding the 1311owing results; $H_{hf}=146.0kOe,\;{\Delta}E_Q=1.88mm/s,\;\theta=36^{\circ},\;\phi=0^{\circ},\;\eta=0.6$, and R=1.9. The Ga ions enter into the both sites octahedral (B) and tetrahedral (A), simultaneously the same amounts of Fe ions migrate from the A to the B site, this result is an agreement with XRD results, too. The ${\Delta}E_Q$ of the A and B site in Mossbauer spectra of the samples $FeCr_{2-x}Ga_xS_4$(x=0.3) are 0.83 and 2.94mm/s, respectively. While they are 0.56 and 2.36mm/s for the $FeCr_{2-x}In_xS_4$(x=0.3). It is noticeable that the ${\Delta}E_Q$ for the Ga doped samples are larger than that of the corresponding In doped samples, in spite of the larger ionic radius for In ions. The bond lengths of Cr-S, for the Ga and In doped samples (x=0.3) are found to be 2.41 and $2.43\;{\AA}$, respectively. We interpret that the larger covalence effect from the smaller bond length induces a large asymmetric charge distribution. Finally, it gives a large quadrupole interaction.

• Korean journal of food and cookery science
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• v.12 no.2
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• pp.186-192
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• 1996

Retrogradation of non-waxy rice (NWR) and waxy rice (WR) cakes (45% moisture) stored at 5$^{\circ}C$, $25^{\circ}C$ and -2$0^{\circ}C$ was studied by differential scanning calorimetry (DSC) and enzymatic ($\beta$-amylase-puuulanase) method. With DSC, endotherms did not appear with rice cakes stored at room ($25^{\circ}C$) and deep freezing (-2$0^{\circ}C$) temperatures but did with samples stored at low temperature (5$^{\circ}C$), showing accelerated retrogradation by low temperature. Onset temperature (To) and peak temperature (Tp) did not change under 14 days at 5$^{\circ}C$ but enthalpy values ($\Delta$H) increased rapidly within one day and increased steadily until 5th day of storage, then equilibrated. Higher $\Delta$H were obtained with WR cakes than NWR cakes. It was suggested that more amylopectin recrystallization occured with WR than NWR. Degrees of gelatinization of rice cakes determined by enzymatic method increased in the following order: 5$^{\circ}C$ < $25^{\circ}C$ < -2$0^{\circ}C$. In contrast with DSC results, dogrees of gelatinization of NWR cakes, were relatively lower than that of WR cakes. However, increased retrogradation extents (melting enthalpies) caused reduced enzyme susceptibilities to $\beta$-amylase-pullulanase system, among NWR or WR cakes stored at 5$^{\circ}C$. The degrees of retrogradation of rice cakes stored at 5$^{\circ}C$ were higher than those stored at $25^{\circ}C$ and -2$0^{\circ}C$ without regard to the kind of rice. The higher sensitivity of the enzymatic method was obtained than that of DSC method when the degrees of retrogradation of rice cakes were determined during storage under this experiment conditions.