Polydiacetylene‐based chemosensors are prepared by assembling liposomes of diacetylene monomers with terminal amine groups on an aldehyde‐modified glass substrate, and polymerizing them by irradiation with UV light. Incubation of the immobilized film sensor in a poly(acrylic acid) solution results in a color change from the original blue (solid line in Figure) to the red phase (broken line).

We have observed the first example of a cyclodextrininduced color change of polymerized diacetylene film sensor. The PDA film, prepared from a diacetylene monomer containing a terminal anilide moiety was found to preferentially interact with a-cyclodextrin causing a color transition which is both time and concentration dependent.

This study was carried out to investigate the effects of various temperatures of electro-magnetic resonance and air blast freezing methods on the physicochemical quality of meat. Beef (loin and round), pork (belly and ham) and chicken (breast and leg) were purchased at a commercial market, and the meat was frozen using three methods: air blast freezing (-20 o C and -45 o C) and electro-magnetic resonance quick freezing. Changes in the physicochemical properties of meat were analyzed by drip loss, cooking loss, water holding capacity (WHC) and proximate compositions. In comparison, regardless of the animal species and cuts of meat, electro-magnetic resonance quick freezing (2 h) resulted in a completely frozen product in a much shorter time than -20 o C and -45 o C air blast freezing (24 h and 8 h, respectively). Drip loss of loin which had underwent electro-magnetic resonance quick freezing were significantly (p<0.05) lower than those of the other two treatments, but cooking loss and water holding capacity were the highest at 43.7% and 60.7%, respectively (p<0.05). Characteristics such as crude protein, crude fat and moisture compositions showed significant differences, depending on the cuts and freezing methods (p<0.05). The fat composition of electro-magnetic resonance quick frozen loin and round were significantly low (p<0.05). However, moisture content was the highest compared to other freezing methods, as 67.1% and 71.9%, respectively (p<0.05). Electro-magnetic resonance quick freezing was an appropriate way to reduce the deterioration of meat quality due to freezing, and the drip loss was least for the part with low moisture, low protein, and high fat. 서 론 식품 냉동은 식품에서 열을 빼앗아 식품 내의 수분을 액 체에서 고체로 상 변화시키는 방법으로 장기 보존을 위한 최선의 방법 중 하나이다. 식육은 냉동 시 드립 발생, 단백 질 변성 및 지방 산화 등이 일어나 품질을 저하시킨다 (Lagerstedt et al., 2008; Mancini and Hunt, 2005). 특히, 식육 의 변성과 연관된 생화학적 반응은 냉동 온도에서도 액상 으로 잔존하는 식육 내의 수분 때문에 일시적으로 정지되 지만 저장 기간의 경과에 따라 진행이 지속된다 (Akamittath et al., 1990; Grujic et al., 1993). 일반적인 식육의 냉동 방 법으로는 정지 공기 냉동법(sharp freezing), 송풍식 냉동법 (air blast freezing), 접촉식 냉동법(contact freezing) 및 침 지식 냉동법(immersion freezing)이 있다. 정지공기 냉동법 은 냉각된 실내에 설치된 선반에 식품을 얹어 놓거나 또는 매달아 놓고 동결시키는 방법으로 응용 범위가 가장 넓고 관리가 용이한 반면 열전도율이 접촉식, 침지식 및 액체 질 소 냉동법보다 낮아 냉동 시간이 상대적으로 긴 단점이 있 는데 이를 보완한 것이 송풍식 냉동법이다. 송풍식 냉동법 은 냉기에 유속을 주어 공기와 시료 간에 열 전달 계수를 크게 하여 빠르게 냉동시키는 방법으로 산업적으로 가장

ABSTRACT:The character and performance of a new ionic polymer-metal composite (IPMC) prepared with a melt-processable fluorinated acrylic copolymer were examined. The fluorinated acrylic copolymer was synthesized by the copolymerization of fluoroalkyl methacrylate (DuPont Zonyl) and acrylic acid, and it was compression molded to attain membranes of various thicknesses. The current and displacement responses by electric stimulus were measured to study the effects of the ionic concentration, thickness, and countercation on the actuation of the IPMC. The ionic center of the acrylic copolymer was essential for the actuation of the IPMC; however, too much ionic center induced excessive water uptake, which caused adverse effects on the performance of the IPMC. When the applied voltage was 5 V, the largest current and displacement responses were observed with the IPMC prepared by a fluorinated acrylic copolymer containing 11.8 wt % acrylic acid.

A new ionomeric polymer-metal composite (IPMC) was prepared using a cast membrane of acrylic copolymer, which was synthesized by radical copolymerization of fluoroalkyl acrylate and acrylic acid (AA). To examine its performance as a new electroactive polymer, the current and displacement responses to a step voltage applied across the IPMC were measured. The largest responses were observed when the AA content in the copolymer was 10.6 wt%.