개발 PLA 필름으로 포장한 파프리카의 신선도

박형우,김상희,이선아 한국포장학회 2011 한국포장학회지 Vol.17 No.1

개발된 3종류의 PLA 필름의 파프리카 포장에의 사용 가 능성을 평가하고자 두 종류의 OPP/PE 필름과 함께 파프리 카 포장에 사용하여 포장별로 상온에서 20일 동안 저장하 면서 품질변화를 살펴보았다. 중량 감소율은 OPP/PE필름은 0.02%에 비해 PLA 필름은 0.18%로 나타났으며 두 포장구 간에 0.16%차로 큰 차이를 보이진 않았다. 수분함량은 PLA1, PLA2 포장구가 적은 감소율을 보였지만 포장재 종 류에 따른 뚜렷하게 큰 차이는 보이지 않았고, 외관변화는 저장 6일째 OPP 포장구에서 꼭지 부분에 곰팡이와 부패가 발생하였으나 PLA 포장구에서는 발생하지 않았다. 경도변화 는 모든 처리구가 저장기간이 지날수록 감소하였으며, OPP 포장구가 PLA 포장구 보다 다소 높은 경도 수치를 나타내 었다. 가용성 고형분 함량은 PLA1 포장구가 가장 적은 변 화를 보였고, 색차 L값은 모든 처리구가 9일째 30이하의 값을 나타내었다. 비타민 C 함량의 변화는 PLA2 포장구가 20% 이하로 가장 적은 감소율을 나타났다. 여러 분석 항목 에서 모든 포장구가 큰 분석차이가 발생하지 않았으나, 외 관상태에서 PLA 필름 포장구는 부패과가 발생하지 않았 다. 즉 저장 9일째 OPP/PE 포장구는 꼭지 부분의 곰팡이 와 부패가 발생하였고, 포장 개봉시 부패취가 심하였다. OPP/PE 포장구에서는 저장 15일째 부패가 매우 심하였으 며 상품성이 전혀 없는 것으로 나타났다. This research was conducted to compare the quality of paprika (Capsicum annuum L.) packed with PLA film and OPP/PE film pouches during storage at 6oC. Weight loss of paprika fruit was higher in OPP/PE film pouches, mold decay was shown in OPP/PE pouches after 6 days, but was not yet shown in PLA pouches. Hardness decreased in all packages. Soluble solid content was highest in PLA1 film pouch, vitamin C content was also highest in PLA2. Mold decay was not shown in PLA pouches after 9 day, but shown at calyx of paprika fruit in OPP/PE pouches. Off-flavor was strong in the OPP/PE pouches when the pouches were opened, decay was also serious in the same pouches after 15 days and thus quality was inadequate for sale in market.

PLA 필름으로 포장한 딸기의 품질

박형우,이선아,김상희,전승호 한국포장학회 2011 한국포장학회지 Vol.17 No.2

포장재별로 처리한 딸기를 10oC에 저장하면서 품질변화 를 살펴보았다. 중량 감소율은 OPP필름에 비해 PLA 필름 이 더 높은 것으로 나타났으나 저장 6일까지 0.12% 이하 의 감소율로 처리구간에 큰 차이를 보이진 않았다. 경도의 경우 펀칭형 PLA3 포장구가 다른 처리구보다 가장 변화가 적은 것으로 나타났으며, 산도변화에서는 펀칭형 PLA2와 PLA3가 가장 적은 변화를 보였고, 색도의 경우는 포장구간 에 유의적인 차이가 없었다. 가용성고형분 함량과 비타민C 함량 변화에서는 PLA2 포장구가 변화율이 가장 적었으며, PLA 필름구가 OPP 포장구 보다 높게 유지되었다. 딸기 포장재로 PLA 필름중 PLA2와 PLA3 필름이 저장에 효과 적임을 알 수 있었다. Effect of several PLA films on strawberry packaging was investigated. Three types of PLA film (non-perforated PLA1, perforated films of PLA2 and PLA3) were used for packing strawberry and the fruit quality was measured during 6 day storage at 10. For comparison, two types of OPP/PE film (non-perforated OPP1 and perforated OPP2) were used for strawberry packaging. Weight loss of all the treatments was below 0.12% after 6 day, seeming to be in tolerable range. PLA3 package showed the best retention in fruit firmness, PLA2 and PLA3 packages the least changes in acidity, and PLA2 package gave the least changes of soluble solid content and vitamin C content. There have been no differences in surface color among packages. Perforated PLA films could be effective for use as packaging of strawberry.

PLA/PBAT/MEA 블렌드의 구조변화 및 열적, 기계적 성질

김태진(Tae Jin Kim),김태희(Tae Hui Kim),김상구(Sang Gu Kim),서관호(Kwan Ho Seo) 한국고분자학회 2016 폴리머 Vol.40 No.3

본 연구에서는 poly(lactic acid)(PLA), poly(butylene adipate-co-terephthalate)(PBAT), ethanolamine(MEA) 블렌드를 제작하였다. MEA는 PLA/PBAT의 에스터 치환반응을 가능하게 하였고, 커플링반응의 촉매로써 작용하였으며, PLA와 PBAT간의 상용성을 증진하게 하였다. PLA/PBAT/MEA 블렌드의 구조 및 열적 특성을 관찰하였고, PLA/PBAT/MEA 블렌드를 PLA/PBAT 블렌드의 커플링제로 사용하였다. 결론적으로 PLA/PBAT/MEA 블렌드는 화학적 결합으로 인하여 상용성을 향상하였고, 커플링제로의 가능성을 보여주었다. In this study, a polymer blend of poly(lactic acid) (PLA), poly(butylene adipate-co-terephthalate) (PBAT), and ethanolamine (MEA) (PLA/PBAT/MEA) was prepared. MEA made PLA/PBAT capable of transesterification reaction, acted as a catalyst of coupling reaction and improved the compatibility between PLA and PBAT. The structural and thermal properties of PLA/PBAT/MEA blend were characterized, and PLA/PBAT/MEA blend was used for the coupling agent of PLA/PBAT blend. In conclusion, the PLA/PBAT/MEA blend had an improved compatibility due to chemical coupling and showed a possibility as a coupling agent.

Biological significance of the multiple PLA2s in Frankliniella occidentalis

Mojtaba Esmaeily,Yonggyun Kim 한국응용곤충학회 2023 한국응용곤충학회 학술대회논문집 Vol.2023 No.10

Eicosanoids represent a category of oxygenated C20 polyunsaturated fatty acids that play a crucial role in regulating various physiological functions in insects. These compounds are synthesized from phospholipids through the enzymatic activity of phospholipaseA2 (PLA2). In this study, we investigated four PLA2 genes encoded in the western flower thrips, Frankliniella occidentalis, with a focus on understanding their specific functions through a variety of experimental approaches. Among the four PLA2s identified, Fo-PLA2A and Fo-PLA2B fall under the category of Ca2+-independent cellular PLA2 (iPLA2), while Fo-PLA2C and Fo-PLA2D are classified a secretory PLA2 (sPLA2). Enzyme activity assays showed that all developmental stages of the thrips exhibited significant activity against both types of PLA2 substrates (arachidonic acid (AA) and non-AA), albeit with variations in enzyme kinetics across different developmental stages. Further examination revealed that all four PLA2 genes were expressed in every developmental stage. Fo-PLA2B and Fo-PLA2C displayed higher expression levels in larvae, while Fo-PLA2A and Fo-PLA2D were predominantly expressed in female and male adults, respectively. These findings support the hypothesis that PLA2s likely serve specific functions during distinct developmental stages. Our results indicated that PLA2s play pivotal roles in mediating various physiological processes such as immunity, development, and reproduction. So, the differential expression of certain PLA2s in various stages suggests that each PLA2 may have a specific role during different stages. Additionally we conducted flouorescens in situ hybridization (FISH) analysis to localize PLA2 transcripts in different tissues, shedding light on their specific functions within these tissues. In summary, the four identified PLA2s are associated with distinct catalytic activities and exhibit differential expressions across developmental stages and tissues, collectively contributing to various physiological processes.

Preparation and Properties of Poly(lactic Acid)/PLA-g-ABS Blends

Charungkit Chaikeaw,Kawee Srikulkit 한국섬유공학회 2018 Fibers and polymers Vol.19 No.10

PLA/PLA-g-ABS blends were prepared and evaluated for mechanical properties performance. Firstly, carboxylic acid functionalized ABS particles were synthesized by grafting polymethacrylic acid (PMAA) onto ABS particle surface using potassium persulfate as an initiator. The reaction was followed by FTIR analysis. The resultant carboxylated ABS was melt mixed with virgin PLA in an internal mixer to obtain PLA/PLA-g-ABS blends. The obtained PLA/PLA-g-ABS blends were subject to injection molding to obtain specimens for testing evaluation. It was found that impact resistance values significantly outperformed neat PLA by 60 %, 87 %, and 150 % for PLA/PLA-g-ABS 10 wt%, PLA/PLA-g-ABS 20 wt%, and PLA/PLA-g-ABS 30 wt%, respectively. A significant increase in impact strength was contributable to ABS rubber which exhibited even dispersion and good interfacial adhesion. The impact strength was dependent on the percent loading of PLAg- ABS; the more the PLA/PLA-g-ABS the higher the impact strength value. In a similar manner, tensile strength increases when loaded with PLA/PLA-g-ABS albeit at lesser effect. Considering the percent elongation, a massive increase in percent elongation was recorded in case of PLA/PLA-g-ABS 20 wt% and PLA/PLA-g-ABS 30 wt%, implying that these blends were extremely flexible and tough when compared to neat PLA, control, and PLA/PLA-g-ABS 10 wt%.

β-TCP 첨가량에 따른 생분해성 PLA/β-TCP 복합체의 생체활성과 기계적 특성 평가

문희정(Hee-Jung Moon),김설악(Seol-Ak Kim),김동애(Dong-Ae Kim) 한국콘텐츠학회 2021 한국콘텐츠학회논문지 Vol.21 No.3

본 연구는 PLA에 β-TCP를 첨가한 복합체의 생체활성도와 기계적 성질을 평가하고자 한다. 클로로프롬 용액에 24 시간 교반기를 이용해서 PLA와 β-TCP를 무게별로 0, 10, 30, 50 wt% 용해한 후 에탄올 용액에서 PLA/β-TCP 복합체를 추출 후 사출성형을 통해 다양한 기계적 평가를 위한 시편을 제작하였다. SBF 인체유사 체액에 1, 7, 30, 90 일 동안 침전하여 생체활성도를 평가하였다. 본 연구 결과 PLA/β-TCP 10-30 wt% 첨가한 실험군에서는 유의하게 강도가 증가하였으나 50 wt% 첨가한 실험군에서는 감소하였다. 결론적으로 β-TCP 30 wt% 이상 첨가하는 것은 사출성형 고분자 복합체의 기계적 특성이 개선되지 않는다. 표면 생체활성도는 90일 침전 후 표면 전체에 아파타이트 결정을 형성하였다. β-TCP는 표면특성과 기계적 성질 개선효과가 있음을 입증하였다. 향후 PLA/β-TCP 첨가량에 따른 효율성과 폭 넓은 물성 연구가 필요할 것으로 사료된다. The aim of the present study was to investigate the mechanical properties of melt-injected poly lactic acid (PLA) composites with β-tricalcium phosphate (β-TCP). The PLA mixed with calcined PLA/β-TCP powder to be contents of 0, 10, 30, 50 wt%, respectively, was dissolved in chloroform solvent under stirring for 24 h. Then the liquid mixtures were dropped into ethanol to extract solvent. After drying, the well-dispersed PLA/β-TCP composites were granulated and melt-injected to prepare specimens for various mechanical testing. PLA/β-TCP induced the precipitation of an apatite bone-mineral phase on the surface after immersion in a human simulated body fluid (SBF) for 90 days, showing in bioactivity. Mean various mechanical properties PLA/β-TCP composite were increased up to 10-30 wt% with significantly in part and composite were decreased 50 wt% of showing in mechanical properties. In conclusion, Over 30 wt% addition of β-TCP to PLA may be not advisable to improve the mechanical properties of melt-injected polymeric composites. Results indicated that β-TCP can be used considered as potential reinforcing agent for increasing mechanical properties for PLA. Therefore, it was suggest that the additional effects of β-TCP and research on a wide range of substances.

저탄소 친환경 PLA 필름으로 포장한 콩나물의 신선도

박형우,김상희,장종근 한국포장학회 2011 한국포장학회지 Vol.17 No.1

포장재별로 처리한 콩나물의 저장 중 품질변화를 살펴보 았다. 중량 감소율은 OPP필름에 비해 PLA 필름이 더 높 은 것으로 나타났으나 0.025% 이하의 감소율로 큰 차이를 보이진 않았다. 수분함량의 경우 PLA3 포장구가 다른 처 리구보다 가장 적은 감소율을 보였으며, 총균수 변화에서는 PLA2, PLA3 포장구가 가장 적은 증가율을 나타내었으며, 외관 상태에서 OPP 포장구는 봉투 개봉시 모든 포장구에 서 부패취가 발생하였다. 비타민C 함량 변화는 PLA2 포장 구가 변화율이 적었으며, PLA3 필름구가 그 다음으로 나 타났으며, 기호도 조사에서는 PLA2 포장구가 모든 항목에 서 높은 점수를 나타냈다. 결과적으로 OPP 포장구 보다는 PLA 포장구의 변화가 적었음을 알 수 있었으며, 그 중 PLA2와 PLA3 필름이 콩나물 저장에 가장 효과적임을 알 수 있었다. Soybean sprouts of 100 g were packed with commercial OPP/PE films and developed PLA films, and stored at 10oC for 6 days. Effects of packaging film were investigated. The weight loss of OPP/PE film was higher than that of the PLA film. Total cell count of PLA2 and PLA3 packages was the lowest among 5 packages. Off-flavor was strong at OPP/PE, but that in PLA2 was very little. Vitamin C content of PLA2 was highest and preference test of PLA2 was also highest among 5 packages. Finally, the PLA packages for soybean sprouts was more suitable than OPP/PE.

L-폴리락타이드, D-폴리락타이드의 합성과 입체복합체 폴리락타이드의 제조 및 특성연구

제갈종건(Jong Geon Jegal),김지현(Ji Hyun Kim),송봉근(Bong Keun Song),신채호(Chae Ho Shin) 한국고분자학회 2011 폴리머 Vol.35 No.1

본 연구에서는 L-lactide, D-lactide를 단량체로 하여 tin 2-octoate, lauryl alcohol을 각각 촉매와 개시제로 사용하여 촉매량(0.5∼1.0 wt%)과 개시제의 양(0.5∼0.1 wt%)을 달리하여 140 ℃에서 lactide의 고리개환중합으로 고분자량의 L-PLA와 D-PLA를 합성하였다. 합성된 PLA는 Mn:30000∼90000 g/mol의 다양한 분자량이 나타났으며 합성된 L-PLA와 D-PLA를 이용해 조성비를 다르게 하여 stereocomplex-PLA를 제조하였다. Stereocomplex-PLA의 용융점, 열분해온도, 열적 안정성은 단일고분자 L-PLA, D-PLA보다 높아짐을 확인하였다. 이러한 결과로 보아 이성질체 L-PLA, D-PLA 분자간 인력이 작용한다는 사실을 예상할 수 있었고 XRD를 통해 모폴로지의 변화를 살펴본 결과 단일고분자와 stereocomplex-PLA는 상이하게 변하는 사실을 확인하였다. 또한 기계적 강도를 측정하여 L-PLA, D-PLA보다 stereocomplex-PLA의 최대응력과 변형률이 증가함을 확인하였다. L-PLA or D-PLA was synthesized in bulk at 140 ℃ by ring opening polymerization(ROP) of L-lactide or D-lactide as a monomer using tin(Ⅱ) octoate and lauryl alcohol as a catalyst and an initiator with changing the amounts of catalyst(0.25∼1.0 wt%) and initiator(0.1∼0.5 wt%). And stereocomplex- PLA was prepared by L-PLA, D-PLA having a wide range of molecular weight(30000∼90000 g/mol) and L-PLA/D-PLA blends having different mixing ratio(XD). The melting temperature, thermal degradation temperature and thermal stability of stereocomplex-PLA were higher than those of homopolymers( L-PLA, D-PLA). We supposed that these improvements arose from a strong interaction between L-PLA and D-PLA. The improved mechanical properties and changes in morphology of LPLA/ D-PLA blends were compared to those of homopolymers(L-PLA, D-PLA).

Specific inhibition of <i>Xenorhabdus hominickii</i>, an entomopathogenic bacterium, against different types of host insect phospholipase A₂

Sadekuzzaman, Md.,Kim, Yonggyun Elsevier 2017 Journal of invertebrate pathology Vol.149 No.-

<P><B>Abstract</B></P> <P>Phospholipase A<SUB>2</SUB> (PLA<SUB>2</SUB>) hydrolyzes ester bond of phospholipids at the <I>sn-2</I> position to release free fatty acid and lysophospholipids. Some PLA<SUB>2</SUB>s preferentially release arachidonic acid which is subsequently oxygenated into eicosanoids to mediate immune responses in insects. <I>Xenorhabdus hominickii</I> is an entomopathogenic bacterium that can suppress insect immunity by inhibiting PLA<SUB>2</SUB> activity. However, little is known about target PLA<SUB>2</SUB> types inhibited by <I>X. hominickii.</I> Therefore, the objective of this study was to determine PLA<SUB>2</SUB> types in the host insect, <I>Spodoptera exigua</I> using specific inhibitors. All developmental stages of <I>S. exigua</I> possessed significant PLA<SUB>2</SUB> activities, with late larval stages showing relatively higher PLA<SUB>2</SUB> activities. In different larval tissues, hemocytes had higher PLA<SUB>2</SUB> activities than fat body, gut, or epidermis. Various developmental and tissue extracts exhibited differential susceptibilities to three different PLA<SUB>2</SUB> inhibitors. Late larva-to-adult stages were highly susceptible to all three different types of PLA<SUB>2</SUB> inhibitors. In contrast, extracts from egg and young larval stages were not susceptible to secretory PLA<SUB>2</SUB> (sPLA<SUB>2</SUB>) or calcium-independent cellular PLA<SUB>2</SUB> (iPLA<SUB>2</SUB>) inhibitors, although they were susceptible to a calcium-dependent cellular PLA<SUB>2</SUB> (cPLA<SUB>2</SUB>) inhibitor in a dose-dependent manner. Different tissues of fifth instars exhibited variation in susceptibility to inhibitors, with epidermal tissue being sensitive to cPLA<SUB>2</SUB> inhibitor only while other tissues were sensitive to all three types of inhibitors. Bacterial challenge with heat-killed <I>X. hominickii</I> significantly increased PLA<SUB>2</SUB> activity. However, live bacteria suppressed the induction of PLA<SUB>2</SUB> activity. An organic extract of <I>X. hominickii</I>-culture broth inhibited the susceptibility of <I>S. exigua</I> to sPLA<SUB>2</SUB>- and iPLA<SUB>2</SUB>- specific inhibitors, but not to cPLA<SUB>2</SUB>-specific inhibitor. Oxindole, a component of the organic extract, exhibited an inhibitory pattern similar to the organic extract. Taken together, our results indicate that <I>S. exigua</I> possesses different PLA<SUB>2</SUB> types and that <I>X. hominickii</I> can inhibit PLA<SUB>2</SUB>s susceptible to sPLA<SUB>2</SUB>- and iPLA<SUB>2</SUB>- specific inhibitors<I>.</I> </P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Xenorhabdus hominickii</I> exhibits entomopathogenicity by inhibiting host PLA<SUB>2</SUB>. </LI> <LI> There are at least three different PLA<SUB>2</SUB>s in the host insect, <I>Spodoptera exigua</I>. </LI> <LI> <I>X. hominickii</I> inhibits sPLA<SUB>2</SUB> or iPLA<SUB>2</SUB> with its secondary metabolite(s). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Analysis of the Effect of Entry-Level 3D Printer Materials on CT Images

박세환(Se-Hwan Park),조현정(Hyun-Jung Jo),이성준(Sung-Jun Lee),이송빈(Song-Bin Lee),박상협(Sang-Hyub Park),류대연(Dae-Yeon Ryu),허영철(Yeong-Cheol Heo) 한국방사선학회 2022 한국방사선학회 논문지 Vol.16 No.6

본 연구에서는 PLA를 기반으로 알루미늄, 나무, 구리, 카본, 대리석이 각각 20% 함유된 재질들의 CT number를 분석하고 영상에 어떠한 영향을 미치는지 분석하고자 하였다. 보급형 3D 프린터를 이용하여 5⨯30⨯30 mm³(두께⨯직경⨯높이)의 원기둥 모양 팬텀을 제작하였다. 관전압을 80, 100, 120 kV로 변화시키고, 관전류초를 100, 200 mAs로 변화시켜 테이블 중앙에 놓인 팬텀을 총 6가지 조건으로 횡단 스캔하였다. Image J를 이용하여 원형의 ROI를 설정하고 물질부 CT number의 정량값과 주변부 CNR의 정량값을 구하였다. 물질부의 CT number 평균값은 PLA-나무20%, PLA-대리석20%, PLA-카본20%, PLA-100%, PLA-알루미늄20%, PLA-구리20% 순으로 높아졌고(p<0.05), kV 증가에 따른 CT number는 음의 상관성을 확인하였다. 주변부의 CNR값은 PLA-대리석20%, PLA-구리20%, PLA-카본20%, PLA-나무20%, PLA-알루미늄20%, PLA-100% 순으로 증가 됨을 확인하였다(p<0.05). 각 재료별 HU 값과 유사한 인체 장기는 PLA-구리20%는 치밀골, PLA-알루미늄20%는 해면골, PLA-100%는 응고된 혈액, PLA-카본20%와 PLA-대리석20%는 간, 근육, 비장, PLA-나무20%는 지방과 유사한 값이었다. 또한 모든 재료에서 필라멘트 주변부 영상을 흐리게 하는 흐림 현상을 확인하였고 특히 PLA-100%에서 영상 주변부 흐림 현상이 가장 많은 것을 확인하였다. 따라서 의료용 팬텀 제작의 재질을 선정할 때 목표 장기의 HU 값을 반영하고, 팬텀 주변부의 흐림 현상을 고려하는 것이 바람직하다고 판단하며 본 연구가 기초 자료를 제공할 수 있을 것이라 사료된다. In this study, based on PLA, we analyzed the Hounsfield Unit (HU) of materials containing 20% each of aluminum, wood, copper, carbon, and marble, and tried to analyze how they affect the image. A cylindrical phantom of 5×30×30 mm3 (thickness×diameter×height) was fabricated using a entry-level 3D printer. The kV was changed to 80, 100 and 120, and the mAs was changed to 100 and 200 mAs, and the phantom in the center of the table was cross-scanned under a total of six conditions. A circular ROI was set using image J program and the quantification value of the material part HU and the quantification value of the peripheral part CNR were obtained. The HU average of the material part increased in the order of [PLA - wood 20%], [PLA - marble 20%], [PLA - carbon 20%], [PLA 100%], [PLA - aluminum 20%], [PLA - copper 20%] (p<0.05) a negative correlation was confirmed with the HU by increasing kV. It was confirmed that the CNR value in the peripheral area increased in the order of [PLA - marble 20%], [PLA - copper 20%], [PLA - carbon 20%], [PLA - wood 20%], [PLA - aluminum 20%], and [PLA - 100%] (p<0.05). Human organs with similar HU values for each material are [PLA - copper 20%] compact bone, [PLA - aluminum 20%] cancellous bone, [PLA 100%] coagulated blood, [PLA - carbon 20%] and [PLA - marble 20%] liver, muscle, spleen and [PLA - wood 20%] had similar values to fat. In addition, we confirmed the blur phenomenon that blurs the image around the filament with all materials, and confirmed that [PLA 100%] especially has the most blur around the filament. Therefore, it is considered desirable to reflect the HU value of the target organ and consider cloudiness around the phantom when selecting materials for medical phantom fabrication, and this research can provide basic data.