• 환경생물
• /
• 제20권1호
• /
• pp.78-84
• /
• 2002

The effects of light and darkness on stomatal aperture and guard cell apoplastic pH in the intact leaf and in the isolated epidermal strips of Commelina communis have been investigated. Stomata in the intact leaf opened wide in the light. In contrast, stomata in the isolated epidermal strips did not respond clearly to light. To eucidate the relationship between the stomatal aperture and the guard cell apoplastic pH, apoplastic pH was measured. In the light the guard cell wall of intact leaf was acidified by pH 1.9 units, falling from pH 7.3 to pH 5.4 in the first 10 minutes. On the contrary, apoplastic pH of isolated epidermal strips changed slowly from pH 7.3 to pH 6.9 at 20 min. Stomata in the intact leaf closed rapidly in the dark. On the other hand, stomata in the isolated epidermal strips failed to close in dark. There was a slow increase in apoplastic pH on transfer to the dark after incubation for 1.5 h in the light and the level observed before the experiment was regained after around 40 min. When the isolated epidermal strips were transferred to the dark, apoplastic pH maintained a uniform level of around pH 7.2-7.4. These results indicate that the mechanism of stomatal opening and closing from isolated epidermal strips and intact leaves could be different.

• Bulletin of the Korean Chemical Society
• /
• 제31권10호
• /
• pp.2867-2872
• /
• 2010

Two new energetic organic alkali metal salts, 1,1-diamino-2,2-dinitroethylene rubidium salt [Rb(FOX-7)${\cdot}H_2O$] and 1,1-diamino-2,2-dinitroethylene cesium salt [Cs(FOX-7)${\cdot}H_2O$], were synthesized by reacting of 1,1-diamino-2,2-dinitroethylene (FOX-7) and rubidium chloride or cesium chloride in alkali methanol aqueous solution, respectively. The thermal behaviors of Rb(FOX-7)${\cdot}H_2O$ and Cs(FOX-7)${\cdot}H_2O$ were studied with DSC and TG methods. The critical temperatures of thermal explosion of the two compounds are 216.22 and $223.73^{\circ}C$, respectively. Specific heat capacities of the two compounds were determined with a micro-DSC method, and the molar heat capacities are 217.46 and $199.47\;J\;mol^{-1}\;K^{-1}$ at 298.15 K, respectively. The adiabatic times-to-explosion were also calculated to be a certain value of 5.81 - 6.36 s for Rb(FOX-7)${\cdot}H_2O$, and 9.92 - 10.54 s for Cs(FOX-7)${\cdot}H_2O$. After FOX-7 becoming alkali metal salts, thermal decomposition temperatures of the compounds heighten with the rise of element period, but thermal decomposition processes become intense.

• 한국식품과학회지
• /
• 제35권4호
• /
• pp.752-755
• /
• 2003

E. coli O157:H7에 대한 마늘즙액의 항균작용을 알아보기 위하여 마늘즙액의 처리량을 농도별 조건을 달리한 후 생균수 측정을 실시하였다. 마늘즙액 농도가 1%에서는 첨가하지 않았을 때에 비해 E. coli O157:H7의 생균수가 약간 줄어들었으나 마늘즙 처리량이 3%에서는 약 5 log, 마늘즙 처리량이 5%로 증가했을 때는 약 6 log의 생균수 감소를 보였다. 마늘즙의 식육내 항균작용 효과를 알아본 결과, 저육에서 3%, 6%, 10%의 마늘즙 농도별 차이에 따른 E. coli O157:H7에 대한 항균효과는 크게 다르지 않음을 알 수 있었다. 마늘즙의 가장 뚜렷한 저해 효과는 저장 9일에 나타나 약 2 log의 생균수 감소가 관찰되었다. 저장 9일 이후에는 E. coli O157:H7의 생균수가 다시 증가하는 것으로 미루어 마늘즙의 항균 효과가 소실되는 것으로 추정된다. 본 실험의 결과, 마늘의 조미료로써의 기능과 더불어 천연 방부제로써의 항균효과에 관한 기초 자료를 얻을 수 있었다.

• Journal of Ginseng Research
• /
• 제25권3호
• /
• pp.136-140
• /
• 2001

배양온도 및 배지의 pH가 인삼 뿌리썩음병균 Cylindrocarpon destructans 후막포자의 발아에 미치는 영향을 배지별로 조사한 결과는 다음과 같다. 배양온도별 후막포자 발아율은 Czap다 solution agar(CSA) 배지가 potato dextrose agar(PDA) 보다 높았다. CSA 배지의 경우에는 배양온도 5~3$0^{\circ}C$에서 후막포자의 발아가 가능하였으며 15~$25^{\circ}C$에서 발아율은 53.2~62.7%로서 발아적정 온도범위로 측정되었다. 후막포자 발아 최적 배양온도는 2$0^{\circ}C$로 발아율은 62.7%이었고, 3$0^{\circ}C$에서는 6.9%의 매우 저조한 발아율을 보였다. PDA배지에서는 5~$25^{\circ}C$에서 후막포자가 발아 가능하였고, 3$0^{\circ}C$에서는 발아가 관찰되지 않았다. 10~2$0^{\circ}C$에서 발아율이 43.6~47.9%로서 발아적정 온도범위로 측정되었다. 후막포자 발아최적 배양온도는 2$0^{\circ}C$로 발아율은 47.9%이었다. C. destructans 후막포자는 CSA 배지의 pH 5.2~8.1 조사범위 전체에서 발아되었으며 발아적정 pH 범위는 pH 6.4~8.1이었다. PDA배지의 경우는 pH 5.2~7.4의 조사범위 전체에서 발아가 확인되었으며 발아적정 pH 범위는 pH 5.2~6.0 이었다. C. destructans 후막포자를 21일간 배양한 후 생성된 균총의 색상을 배지 pH별로 조사한 결과, CSA 배지의 경우 pH 5.2~6.0 범위에서 연한 갈색, pH 6.4~8.1 에서 백색의 균총을 형성한 반면, PDA 배지에서는 pH 5.2~7.1에서 C. destructans의 전형적인 암갈색 균총을 형성하였고 pH 7.2에서는 갈색균총을 형성하였다.

• International Journal of Industrial Entomology and Biomaterials
• /
• 제8권2호
• /
• pp.189-194
• /
• 2004

Amylase isozyme based three multivoltine viz., N+p, Np, N+ $p^{cho}$ and two bivoltine-D6+p, D6p syngenic lines (Syn. L) were developed from germplasm (GP) stocks Nistari (N) and D6 respectively. haemolymph isozyme pattern at pH 7.0 and 8.5 depicted a total 11 number (Am $y_{1 to 6}$ at pH 7.0 and Am $y^{l to 5}$ at pH 8.5) of native proteins (NP) of various sizes are amylase isozyme expressers. Among eleven NPs, two NPs of 770 kDa (Am $y^{6}$ at pH 7.0) and 376 kDa (Am $y^3$ at pH 8.5) are $\alpha$-amylase expressers and remaining NPs of 370, 364, 350, 329 and 274 kDa at pH 7.0 and 206, 292, 416, 725 kDa at pH 8.5 are $\beta$-amylase expressers. Accordingly, digestive juice amylase isozyme pattern at aforesaid pH also depicted a total number of 10 NPs (Am $y^{1 to 5}$) at each pH 7.0 and 8.5 are amylase expressers of which NP of 387 kDa (Am $y^4$ at pH 7.0) and 780 kDa (Am $y^{5}$ at pH 8.5) are a-amylase expresser. Remaining NPs of 338,297 ＆ 216 kDa at pH 7.0 and 370, 341, 329 ＆302 kDa at pH 8.5 are $\beta$-amylase expresser. Recurrent backcross lines (RBL) viz., N+pRBL and NpRBL were developed through introgression of high shell weight character (a multigenic trait) to be used further for congenic line (Con. L) development and to understand any association with introgressed character. Isozyme pattern in haemolymph of RBLs depicted only one $\alpha$-amylase of 770 kDa at pH 7.0 and 376 kDa at pH 8.0 with three and four respective $\beta$-amylase bands but in bivoltine lines numbers of $\beta$-amylase bands vary between 1 to 2 at aforesaid pH. Variability was also observed in digestive juice of multivolitine and its RBLs but bivoltine lines express null activity at both pH except appearance of one very week $\alpha$-amylase band D6+p at pH 8.5. Overall study suggests that not a single NP at both pH is common for expression of any band of amylase isozyme i.e., a totally different set of proteins are the amylase isozyme expresser at specific pH and no molecular factor of amylase is associated in developed RBLs which showed improvement on survival, single cocoon shell weight (SCSW) and single filament length over receptor parents.s.s.s.

• 공업화학
• /
• 제28권5호
• /
• pp.597-600
• /
• 2017

4,4'-비피리딘과 크롬(VI) 산화물을 반응시켜 $(C_{10}H_8N_2H)_2Cr_2O_7$을 합성하였다. 적외선분광광도법(FT-IR)과 원소분석으로 구조를 확인하였다. 여러 가지 용매 하에서 $(C_{10}H_8N_2H)_2Cr_2O_7$을 이용하여 벤질알코올의 산화반응을 측정한 결과, 용매의 유전상수 값이 증가함에 따라 반응수율이 증가했다. 그 순서는 DMF (N,N'-디메틸포름아미드) > 아세톤 > 클로로포름 > 시클로헥센이었다. $H_2SO_4$ 촉매를 이용한 DMF 용매 하에서, $(C_{10}-H_8N_2H)_2Cr_2O_7$은 벤질알코올(H)과 그의 유도체들($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$)을 효과적으로 산화시켰다. 전자받개 그룹들은 반응속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰고, Hammett 반응상수(${\rho}$) 값은 -0.70 (308 K)이었다. 본 실험에서 알코올의 산화반응 과정은 속도결정단계에서 수소화 전이가 일어났다.

• 한국식품위생안전성학회지
• /
• 제12권4호
• /
• pp.310-314
• /
• 1997

Antithiamin activities of BHA, BHT, PG and TBHQ of synthetic antioxidants on the effect of temperature and pH was determined by means of HPLC. The influence of synthetic antioxidants on the degration of thiamin was found to be dependent on temperature and pH. The degradation of thiamin was considerably more rapid at pH 7 than pH 4. The influence on the heat of synthetic antioxidants at pH 4 and 38* was extremely slight, but the degradation of thiamin at pH 7 was much more rapid at 60* than at 38*. After 24 hours of incubation both PG and TBHQ at pH 7 and 60* nearly completely destroyed thiamin. Tests of antithiamin activities showed that TBHQ, which was decomposed completely in 72 hours, was more effective than PG at pH 7 and 38* but BHA and BHT hardly had antithiamin activities which was evaluated under various reactions of pH and temperature. Thiamin degradation, at pH 7 and 6$0^{\circ}C$, was proportional to the concentration of PG. When the ratio of PG to thiamin was increased from 0.15:1 to 2:1, the degradation rate also increased. However, the change between ratio of 1:1 and 2:1 was negligible.

• 한국축산식품학회지
• /
• 제18권1호
• /
• pp.63-74
• /
• 1998

Recently the high outbreaks of intestinal disease caused by the consumption of frozen dairy foods containing pathogenic bacteria has generated considerable interest in the causative agent such as Listeria monocytogenes and E. coli O157:H7. This study was carried out to detect the above pathogens and compare the microbiological qualities of three commercial forzen yogurt products. The main results obtained were as follows. L. monocytogenes coliforms and E. coli O157:H7 were not detected in the total of seven frozen yogurt samples. For microbiological qualities the viable lactic counts of products manufactured by FA company were about 2.9$\times$108 -1.6$\times$109cfu/ml 1.7$\times$106 cfu/ml for FB's and 1.2$\times$106 cfu/ml for FC's The PH values of FA's FB's and FC's products was in the range of pH 4.1~5.3 and the values of FA's were 4.1~4.6 compared by the pH 5.2~5.3 of FB's and FC's products. During refrigeration of the test samples the survival rates of L. monocytogenes spiked into thawed frozen yogurt sample(FA's FB,s and FC's) were 0.55% 15.61% and 16.89% respectively. On the other hand E. coli O157:H7 and L. monocytogenes were 12.4% and 25.0% for FA's 10.8% and 20.8% for FB's and 10.26% and 22.7% for FC's under 37$^{\circ}C$ storage, As the results described above each frozen yogurt products were different in microbiological qualities. The survival rates of pathogens spiked into the samples increased with the pH of the products. This indicates that the pH or any other factors pre-sumable supressed the growth of E. coli O157:H7 and L. monocytogenes in frozen yogurt products.

• Bulletin of the Korean Chemical Society
• /
• 제7권5호
• /
• pp.412-412
• /
• 1986

• 한국식품과학회지
• /
• 제50권4호
• /
• pp.414-419
• /
• 2018

병원성 대장균 O157:H7은 식중독 사고를 일으키는 주된 원인균으로서 항생제 내성 문제를 극복하기 위해서는 병원성 대장균 O157:H7을 제어하기 위한 새로운 방법이 개발되어야 한다. 따라서 본 연구에서는 식물화학물질을 스크리닝하여 병원성 대장균 O157:H7의 부착에 주된 역할을 하는 LEE 오페론의 발현을 감소시키는 물질을 찾고자 하였다. 스크리닝을 통해 선발된 식물화학물질 중 다이오스민은 사람 결장 상피세포 부착능을 3.62배 감소시킴으로써(p<0.01) 양성대조군으로 사용된 미리세틴과 유사한 정도의 효과를 나타냈다. 생물막 형성에 있어서는 다이오스민 처리 시 표현형이 25.6% 감소하여 유의적 차이가 확인되었고(p<0.05), curli 유전자의 발현 역시 미리세틴 처리 때보다 1.57-2.60배 더 유의미하게 감소하는 것으로 나타나 양성대조군보다 더 좋은 효과를 보였다. 한편 다이오스민은 병원성 대장균 O157:H7의 생장에는 아무런 영향을 미치지 않는 것으로 나타나 내성 발생률이 저감화된 새로운 항미생물제재로서 사용 가능하리라 판단된다.