• Bulletin of the Korean Chemical Society
• /
• 제17권9호
• /
• pp.840-845
• /
• 1996

Rate constants have been measured spectrophotometrically for the reactions of p-and m-nitrophenyl 2-thiophenecarboxylate (5a and 5b, respectively) with alkali metal ethoxides (EtO-M+) in absolute ethanol at 25.0±0.1 ℃. The reactivity of EtO-M+ exhibits dependence on the size of alkali metal ions, i.e. the reactivity of EtO-M+ toward 5a decreases in the order EtO-K+ ≥ EtO-Na+ > EtO-Li+ > EtO-, while the one toward 5b does in the order EtO-Na+ ≥ EtO-K+ > EtO-Li+ > EtO-. This result indicates that ion paired EtO-M+ is more reactive than dissociated EtO-, and alkali metal ions form complexes with the substrate more strongly at the transition state than at the ground state. The catalytic effect shown by alkali metal ions appears to be less significant in the reaction of 5 than in the corresponding reaction of 4, indicating that complexation of alkali metal ions with 5 is not as strong as the one with 4.

• Applied Biological Chemistry
• /
• 제27권3호
• /
• pp.214-216
• /
• 1984

Alkali gelatinization of rice, corn, arrow root and ginger root starches at various sodium hydroxide concentrations was investigated. Critical concentrations of alkali for starch gelatinization ranged from 2.33 to 3.17 meq NaOH per gram of starch. Ginger root starch was most resistant to alkali gelatinization and arrow root starch was least stable to alkali.

• 시멘트 심포지엄
• /
• 1호
• /
• pp.69-91
• /
• 1973

To obtain a more accurate results in alkali analysis of cement and its raw materials we must solve some difficult problems. The most important problem is not only dissoloing the sample with keep up alkali content but compensating interference effects. Her

• 시멘트
• /
• 통권49호
• /
• pp.38-41
• /
• 1972

• 펄프종이기술
• /
• 제46권4호
• /
• pp.69-75
• /
• 2014

Effects of alkali swelling of HwBKP (hardwood bleached kraft pulp) at a low concentration below 2 percent (based on the oven-dried weight of pulp) on handsheet properties were investigated. Swelling treatment of HwBKP was performed at various low NaOH concentrations with/without beating. Then, the changes in handsheet properties were evaluated in terms of bulk, optical and strength properties. It was found that bulk was slightly increased when the alkali concentration was increased. When the pulp was only swollen without beating, paper optical and strength properties was slightly decreased or not changed with alkali concentration. When the pulp was alkali-swollen after beating, paper strength and opacity showed almost no changes while brightness was increased. When the pulp was beaten after NaOH swelling, alkali concentration showed almost no effect on brightness and opacity of paper. Paper strength was slightly decreased with alkali concentration, suggesting that alkali pretreatment before refining could adversely affect refining efficiency.

• 콘크리트학회지
• /
• 제6권2호
• /
• pp.108-117
• /
• 1994

국내에서는 아직 알칼리-골재 반응으로 인한 피해가 보고되지는 않았지만, 해사와 쇄석의 사용이 증가하고 있어 이에 대한 연구가 시급히 진행되어야 할 것으로 사료되어, 화학법(KS F 2545, ASTMC 289)과 모르터바법(KS F 2546, ASTM C 227)을 중심으로 실험을 행하여 국내산 쇄석1종과 국외산 쇄석 1종이 유해로 판정되었으며, 첨가알칼리성량 및 종류를 달리하여 실시한 모르터바법 시험결과 첨가 알카리로 NaCl사용시 가장 높은 팽창을 하였다. 또한, 모르터바의 표면 및 내부의 반응생성물을 SEM에 의한 관찰과 EDXA에 의한 성분분석을 실시하여 알칼리와 실리카성분으로 이루어진 알칼리 실리케이트 겔임이 판명되어 국내에서 알칼리 반응성을 나타내는 골재의 존재가 처음으로 확인되었다.

• 한국염색가공학회지
• /
• 제11권5호
• /
• pp.22-29
• /
• 1999

The increase in color depth of polyester fiber dyed with black disperse dyes was investigated with respect to the kinds of resins and alkali treatment. The color depth of the dyed polyester fiber increased continuously according to the concentration of resins coated onto the fabrics. The alkali treatment to polyester fiber before dyeing also enhanced the color depth. It was thought that the polyester fiber was hydrolyzed by alkali resulting micropores on the sample. And the following treatment with a resin, Jet Black T-101, to the polyester fiber increased the color depth much higher. The successive process of alkali treatment, dyeing and Jet Black T-101 treatment could give the best color depth to polyester fiber. Although the alkali treatment reduced the tensile strength of polyester fiber, the color depth of polyester fiber enhanced sufficiently within the range of practically acceptable weight loss and strength. To analyze the micropore on the polyester fiber formed by alkali treatment, nitrogen porosimeter was used. As the weight loss of polyester fiber treated with alkali increased, the BET(Brunauer-Emmett-Teller) surface area, total pore volume, and average pore size of the sample increased.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
• /
• pp.1015-1018
• /
• 2004

We investigate the influence of the New Electron Injection Layers (EIL) on the performance of the Alkali Metal Complex vapor-deposited Organic Light Emitting Diodes(OLED). Two different Alkali Metal Complex were used; Lithium Quinolate (Liq), and Sodium Quinolate (Naq). In all cases, $Alq_3$ was the Electron Transporting Layer (ETL). We measure and compare the current density-voltage (J-V) and luminance-voltage (L-V) characteristics. We concluded that the turn-on voltage, and luminance efficiency are controlled by the type of EIL material used. We show the longer life-time OLED with Alkali Metal Complex EIL than OLED with LiF EIL. And we show the Optimized Alkali Metal Complex thickness is 3nm. Existent LiF to because is inorganic material, there is trouble to do epitaxy into thin layers but regulates the thickness in case of Alkali Metal Complex matter characteristic that is easy be. Alkali Metal Complex also appeared by sensitive thing in thickness than LiF If utilize this material, It is thought much advantages may be at common use of OLED.

• 펄프종이기술
• /
• 제46권3호
• /
• pp.65-72
• /
• 2014

In this study, effects of alkali swelling at low concentration below 2 percent on properties of hardwood bleached kraft pulp (HwBKP) were elucidated. Swelling treatment of HwBKP was performed at various NaOH concentrations with/without beating. Then, the swelling characteristics of pulp fiber was evaluated by measuring the solvent retention values such as water retention value (WRV) and isopropyl alcohol retention value (LRV). It was found that fiber characteristics were influenced by NaOH swelling even at low alkali concentration and beating treatment as well. The values of WRV and LRV were decreased when the alkali concentration was increased. It is the result from the decreased acidic groups of pulp which were formed during beating. The acidic groups could be neutralized and then removed by alkali. The difference between WRV and LRV was decreased with increasing alkali concentration while the difference was increased when the alkali swollen pulp was beaten. In addition, the crystalline structure of HwBKP was almost not changed while the crystallinity was influenced by swelling treatment at a low alkali concentration.

• 한국식품과학회지
• /
• 제39권6호
• /
• pp.637-643
• /
• 2007

옥수수 전분의 용해도, 아밀로오스 용출량 및 용출당 함량은 알칼리 호화도에 따라 모두 증가하였다. 알칼리호화의 경우 낮은 호화도에서도 특정 X-ray 회절각도에서의 강도 및 DSC의 호화 엔탈피가 감소하여 가열호화와는 달리 호화 초반에 전분입자의 결정질이 손상되는 것을 알 수 있었으며, 결정질이 손상됨에 따라 용출당 중의 아밀로오스의 상대적 함량이 낮아지고 호화과정중의 전분 입자크기는 거의 변하지 않았다. 또한 DSC의 흡열곡선이 호화도가 증가함에 따라 고온으로 이동하였다. 이와 같은 현상으로 미루어 볼 때 알칼리 첨가에 의하여 전분입자의 팽창보다는 약한 결정질로부터 파괴되면서 호화가 진행되는 것으로 추정된다.