• Asian-Australasian Journal of Animal Sciences
• /
• 제18권7호
• /
• pp.1048-1060
• /
• 2005

Dietary acidifiers appear to be a possible alternative to feed antibiotics in order to improve performance of weaning pigs. It is generally known that dietary acidifiers lower gastric pH, resulting in increased activity of proteolytic enzymes, improved protein digestibility and inhibiting the proliferation of pathogenic bacteria in GI tract. It is also hypothesized that acidifiers could be related to reduction of gastric emptying rate, energy source in intestine, chelation of minerals, stimulation of digestive enzymes and intermediate metabolism. However, the exact mode of action still remains questionable. Organic acidifiers have been widely used for weaning pigs' diets for decades and most common organic acidifiers contain fumaric, citric, formic and/or lactic acid. Many researchers have observed that dietary acidifier supplementation improved growth performance and health status in weaning pigs. Recently inorganic acidifiers as well as organic acidifiers have drawn much attention due to improving performance of weaning pigs with a low cost. Several researchers introduced the use of salt form of acidifiers because of convenient application and better effects than pure state acids. However, considerable variations in results of acidifier supplementation have been reported in response of weaning pigs. The inconsistent responses to dietary acidifiers could be explained by feed palatability, sources and composition of diet, supplementation level of acidifier and age of animals.

• 분석과학
• /
• 제8권1호
• /
• pp.47-53
• /
• 1995

수용액에서 $TPB^-$와 $PG^+$의 회합을 흡수 및 형광분광법으로 연구하였다. 1, 4-dioxane을 PG-TPB 수용액에 첨가하면 순수한 물보다 용매의 소수성이 증가되어 $PG^+$와 $TPB^-$ 사이의 회합체가 해리되었고, $PG^+$만의 수용액보다 $PG^+$ 단위체의 농도가 더 크게 나타났다. 물을 제외한 모든 유기 용매에서 회합은 관찰되지 않았고, 최대 흡수는 ${\pi}^*$ 척도와 $(n^2-1)/(2n^2+1)$ 함수를 사용하였을 때가 비교적 좋은 직선 관계를 주었다. 그러나 알코올의 경우는 ${\pi}^*$ 척도를 사용하였을 때가 더 훌륭한 직선 관계를 주었다.

• Journal of Microbiology and Biotechnology
• /
• 제9권3호
• /
• pp.303-310
• /
• 1999

A cost-effective mass production method for a strong antimicrobial peptide, buforin II, which was isolated from the stomach of Bufo bufo gargarizans, has been developed. This method is based on the neutralization of the positive charge of buforin II by fusion with a cysteine-rich acidic peptide (CAP) to avoid any lethal effect on the host. The neutralized fusion peptide was multimerized and expressed in Escherichia coli as tandem repeats to increase the production yield. Multimers of the CAP-buforin II fusion peptide were successfully expressed at high levels in E. coli as inclusion bodies. More than 100mg of pure buforin II was obtained per 11 of E. coli culture after cleaving the multimeric polypeptide with CNBr. The buforin II obtained from the recombinant E. coli had antimicrobial activity identical to that of natural buforin II. The proposed expression system can provide a cost-effective mass production method for both antimicrobial peptides and other host-lethal basic proteins.

• 한국수학교육학회지시리즈B:순수및응용수학
• /
• 제27권3호
• /
• pp.137-155
• /
• 2020

Redundancy is commonly employed to improve system reliability. In most situations, components in the standby configurations are assumed statistically similar but independent. In many realistic models, all parts in standby are not treated as identical as they have different failure possibilities. The operational structure of the system has subsystem-1 with five identical components working under 2-out-of-5: G; policy, and the subsystem-2 has two units and functioning under 1-out-of-2: G; policy. Failure rates of units of subsystems are constant and assumed to follow an exponential distribution. Computed results give a new aspect to the scientific community to adopt multi-dimension repair in the form of the copula.

• 분석과학
• /
• 제11권3호
• /
• pp.202-205
• /
• 1998

X선 흡수 미세구조 분석 기술을 이용하여 Ni-Zn 도금 강판에서의 Ni 주위 국부구조를 연구하였다. 실험적으로 측정한 X선 흡수 미세구조 스펙트럼과 이론적인 스펙트럼을 비교 분석함으로서 Ni-Zn 원자간 거리와 Debye-Waller factor를 결정하였는데 이때 측정 온도의 범위는 80K로부터 300K까지이었다. 이 측정 온도 범위내에서는 Ni-Zn 원자간 거리의 온도에 따른 변화는 매우 작았으며 원자간 거리의 평균값은 $2.557{\AA}$이었다. 그리고 이러한 Ni-Zn 원자간 거리의 값을 순수한 Zn 금속 재료의 가장 가까운 이웃 원자간 거리의 값과 비교하여 볼 때 Ni-Zn 전기 도금층의 Ni 원자 주위에 약간의 contraction이 있는 것을 알 수 있었다. 한편, Debye-Waller factor는 온도에 따라 0.005~0.011 정도의 값을 가지며 비교적 큰 온도 의존도를 가지는 것으로 나타났다.

• 분석과학
• /
• 제16권6호
• /
• pp.499-503
• /
• 2003

Biotin을 4-bromomethyl-6,7-dimethoxycoumarin (BrMDMC), 18-crown-6와 $K_2CO_3$를 사용하여 형광성 유도체로 만들어 (들뜸 파장 360 nm, 방출파장 410 nm에서) 기울기 용리 HPLC 분석을 하였다. 검정선의 농도범위는 5 ~ 400 ng, 검출한계는 2 ng, 회수율 98.75%, 그리고 상대표준편차는 1.1% 이었다. 시료의 전처리는 Sep-Pak $C_{18}$ catridge를 이용하였고, 유도체 제조의 중탕온도는 $50^{\circ}C$에서 30분간 시행하였다.

• Mass Spectrometry Letters
• /
• 제7권3호
• /
• pp.79-83
• /
• 2016

We prepared solid dispersion formulations of quercetin to enhance its solubility and dissolution rate. Various quercetin-loaded solid dispersion were tested with quercetin, poloxamer 407, and carrier such as hydroxypropyl methyl cellulose (HPMC), polyethylene glycol 8000 (PEG 8000), and polyvinylpyrrolidone K40 (PVP K40) using solvent evaporation and freeze drying methods in terms of both the aqueous solubility and the dissolution rates of quercetin. The solubility of quercetin as its solid dispersion formulations was markedly improved compared with that of quercetin powder. Especially, highest solubility of quercetin was observed when HPMC was used as a carrier. The cumulative dissolution of quercetin within 360 min from solid dispersion composed of quercetin, poloxamer 407, and HPMC was 8.8-fold higher than the dissolution of pure quercetin. The results of powder X-ray diffraction (XRD) and scanning electron microscope (SEM) indicated that quercetin transformed from a crystalline to an amorphous form through the solid dispersion formulation process. These results suggest that the solid dispersion formulation of quercetin with poloxamer 407 and HPMC could be a promising option for enhancing the solubility and dissolution rate of quercetin.

• 공업화학
• /
• 제31권5호
• /
• pp.552-559
• /
• 2020

Activated carbon-nickel (II) oxide (AC-NiO) electrodes were studied as materials for the capacitive deionization (CDI) of aqueous sodium chloride solution. AC-NiO electrodes were fabricated through physical mixing and low-temperature heating of precursor materials. The amount of NiO in the electrodes was varied and its effect on the deionization performance was investigated using a single-pass mode CDI setup. The pure activated carbon electrode showed the highest specific surface area among the electrodes. However, the AC-NiO electrode with approximately 10 and 20% of NiO displayed better deionization performance. The addition of a dielectric material like NiO to the carbon material resulted in the enhancement of the electric field, which eventually led to an improved deionization performance. Among all as-prepared electrodes, the AC-NiO electrode with approximately 10% of NiO gave the highest salt adsorption capacity and charge efficiency, which are equal to 7.46 mg/g and 90.1%, respectively. This finding can be attributed to the optimum enhancement of the physical and chemical characteristics of the electrode brought by the addition of the appropriate amount of NiO.

• 대한전자공학회논문지TC
• /
• 제37권5호
• /
• pp.17-24
• /
• 2000

자체 설계 및 제작된 개방단말 동축선 프로브를 이용하여 마른 모래의 복소 유전율을 측정하였다. 프로브의 간단한 교정 방안으로 순수한 물에 대해 측정된 반사계수와 수치계산한 반사계수간의 위상차를 모래에 대해 측정된 반사계수의 위상에 뺐다. 그 다음 마른 모래에 대해 측정된 반사계수를 개선된 가상의 동축선 모델에 대입하여 복소 유전율을 환산하였다. 동일한 마른 모래에 대해 측정된 정확한 측정자료와 비교함으로써 본 측정방법의 정확성을 입증하였다.

• 한국환경과학회지
• /
• 제14권7호
• /
• pp.683-689
• /
• 2005

The consecutive combination process of a biological process as the pre-treatment and a chemical process as the post-treatment is applied for the dyeing wastewater. The poor efficiency of biological treatment using pure oxygen makes the chemical treatment cost high. It is necessary to improve the efficiency of biological treatment in order to reduce the cost of chemical treatment. The purpose of this paper is to find the minimum dose of chemical reagent to fit the Discharged Water Quality Standards for the different biological treatment effluents. Results revealed that the minimum dosage of Fenton's reagent lead to save the cost of chemical treatment based on the guideline dose in the treatment plant. The possible maximum saving reagents was up to $70\%$ for the effluent of the pilot plant packed with the carrier imbedded microorganisms which were selected from the present treatment plant.