Low thermal conductivity carbon material from electrospinning and subsequent chemical activation

Gbewonyo Spero,Xiu Shuangning,Shahbazi Abolghasem,Zhang Lifeng 한국탄소학회 2020 Carbon Letters Vol.30 No.3

Low thermal conductivity carbon fbers from polyacrylonitrile (PAN) are currently being explored as an alternative for tradi�tional rayon-based carbon fbers with a thermal conductivity of 4 W/m K. Compared to multiple component electrospinning, this research demonstrated another feasible way to make low thermal conductivity carbon fbrous material by electrospinning PAN followed by carbonization and alkali activation. The efects of activation condition on microstructure, pore formation, and thermal conductivity of the resultant carbon nanofbrous material were investigated. The processing-structure-thermal conductivity relationship was revealed and mechanism of thermal conductivity reduction was discussed. The overall thermal conductivity of the prepared carbon nanofbrous material is a result of combined efects from factors of carbon structure and number of pores rather than volume of pores or specifc surface area. The activated carbon nanofbrous materials showed thermal conductivity as low as 0.12 W/m K, which is a reduction of~99% when compared to that of solid carbon flm and a reduction of~95% when compared to that of carbon nanofbrous material before activation.

가열 전처리에 따른 피망의 품질 특성 변화

한국산업식품공학회 한국산업식품공학회 2015 산업 식품공학 Vol.19 No.2

본 연구에서는 피망의 동결 전 가열처리 조건을 선정하 기 위해 열수침지, 과열증기 및 볶음 처리 조건에 따른 품 질 특성 변화를 조사하였다. 피망의 외관, 색도, 경도, 미세 구조 관찰 등의 결과로 각 방법별 두 가지 조건을 선정 후 영양학적 품질 조사를 실시하였다. 가열처리 후 피망의 ΔE 값은 처리 시간에 따라 감소하는 경향을 보였고, 특히 볶음 처리시 감소폭이 큰 것으로 나타났다. 열수침지 및 과열증기 처리에 따른 pH 변화는 적었지만, 볶음 처리 후 감소하였다. 경도는 가열처리 후 대체적으로 감소하는 경 향을 보였고, 열수침지 및 볶음 처리 시간이 길수록 경도 는 급격히 감소하는 경향을 보였다. 피망의 일반성분, 비타 민 C, 유리당 및 유기산 함량은 가열처리 방법 및 처리 시간에 따라 유의적인 영향을 받았다. 비타민 C 함량은 열 수침지>과열증기>볶음 처리 순으로, 처리 시간이 길수록 감소량이 큰 것으로 나타났다. 피망의 수용성 성분인 유리 당 및 유기산 함량은 볶음 처리에 비해 열수침지 및 과열 증기 처리시 감소량이 많았다. Peroxidase 활성은 짧은 시 간의 열수침지(2분) 및 과열증기(3분) 처리에도 약 90% 이 상의 불활성화율을 나타냈지만, 볶음 처리시에는 peroxidase 활성 억제 효과가 20% 이하로 낮았다. 이상의 결과로부터 피망의 가열처리 조건은 색도, 경도, 비타민 C, 유리당 등 변화는 적고 peroxidase 억제 효과가 높은 증기처리법으로 3분간 처리하는 것이 적합할 것으로 판단된다. The thermal pre-treatment is an important process to minimize quality change in main cooking or storage. This study was conducted to investigate the effect of different thermal pre-treatment methods (blanching, steaming, and stir-frying) on the quality properties of bell pepper (BP). Washed and sliced BP were treated by blanching (100oC, 1-10 min), steaming (100oC, 1-10 min), and stir-frying with oil (180oC, 10-70 sec). Raw and treated BP was measured for color, pH, hardness, proximate composition, ascorbic acid, free sugar, organic acid, and peroxidase activities. Color and hardness were significantly decreased by blanching, steaming, and stir-frying. Stir-frying, in particular, rapidly decreased the ΔE values and hardness of BP. Blanching and steaming slightly increased the pH compared with raw BP, whereas stir-frying rapidly decreased the pH values. Results showed that the proximate composition, ascorbic content, free sugar content, and organic acid content were significantly (p<0.05) affected by the thermal pre-treatment and that the loss rate varied among individual compounds. Blanching, steaming, and stir-frying significantly reduced the ascorbic acid content (29.4-55.2%), fructose content (8.6-45.1%), and glucose content (8.1- 41.9%) in the BP. Oxalic acid, citric acid, succinic acid, and furmaric acid as organic acid in BP were detected and their contents were significantly (p<0.05) reduced during thermal pre-treatment. In conclusion, the results demonstrated that steam treatment for 3 min could be the best optimal thermal pre-treatment condition for BP to minimize the quality changes.

가열 전처리에 따른 피망의 품질 특성 변화

황인국 ( In Guk Hwang ),김광일 ( Kwang Il Kim ),조연지 ( Yeon Ji Jo ),최미정 ( Mi Jung Choi ),민상기 ( Sang Gi Min ),유선미 ( Seon Mi Yoo ) 한국산업식품공학회 2015 산업 식품공학 Vol.19 No.2

본 연구에서는 피망의 동결 전 가열처리 조건을 선정하기 위해 열수침지, 과열증기 및 볶음 처리 조건에 따른 품질 특성 변화를 조사하였다. 피망의 외관, 색도, 경도, 미세구조 관찰 등의 결과로 각 방법별 두 가지 조건을 선정후 영양학적 품질 조사를 실시하였다. 가열처리 후 피망의 ΔE 값은 처리 시간에 따라 감소하는 경향을 보였고, 특히 볶음 처리시 감소폭이 큰 것으로 나타났다. 열수침지 및 과열증기 처리에 따른 pH 변화는 적었지만, 볶음 처리 후감소하였다. 경도는 가열처리 후 대체적으로 감소하는 경향을 보였고, 열수침지 및 볶음 처리 시간이 길수록 경도는 급격히 감소하는 경향을 보였다. 피망의 일반성분, 비타민 C, 유리당 및 유기산 함량은 가열처리 방법 및 처리 시간에 따라 유의적인 영향을 받았다. 비타민 C 함량은 열수침지>과열증기>볶음 처리 순으로, 처리 시간이 길수록감소량이 큰 것으로 나타났다. 피망의 수용성 성분인 유리당 및 유기산 함량은 볶음 처리에 비해 열수침지 및 과열증기 처리시 감소량이 많았다. Peroxidase 활성은 짧은 시간의 열수침지(2분) 및 과열증기(3분) 처리에도 약 90% 이상의 불활성화율을 나타냈지만, 볶음 처리시에는 peroxidase활성 억제 효과가 20% 이하로 낮았다. 이상의 결과로부터 피망의 가열처리 조건은 색도, 경도, 비타민 C, 유리당 등 변화는 적고 peroxidase 억제 효과가 높은 증기처리법으로 3분간 처리하는 것이 적합할 것으로 판단된다. The thermal pre-treatment is an important process to minimize quality change in main cooking or storage. This study was conducted to investigate the effect of different thermal pre-treatment methods (blanching, steaming, and stir-frying) on the quality properties of bell pepper (BP). Washed and sliced BP were treated by blanching (100oC, 1-10 min), steaming (100oC, 1-10 min), and stir-frying with oil (180oC, 10-70 sec). Raw and treated BP was measured for color, pH, hardness, proximate composition, ascorbic acid, free sugar, organic acid, and peroxidase activities. Color and hardness were significantly decreased by blanching, steaming, and stir-frying. Stir-frying, in particular, rapidly decreased the ΔE values and hardness of BP. Blanching and steaming slightly increased the pH compared with raw BP, whereas stir-frying rapidly decreased the pH values. Results showed that the proximate composition, ascorbic content, free sugar content, and organic acid content were significantly (p<0.05) affected by the thermal pre-treatment and that the loss rate varied among individual compounds. Blanching, steaming, and stir frying significantly reduced the ascorbic acid content (29.4-55.2%), fructose content (8.6-45.1%), and glucose content (8.1- 41.9%) in the BP. Oxalic acid, citric acid, succinic acid, and furmaric acid as organic acid in BP were detected and their contents were significantly (p<0.05) reduced during thermal pre-treatment. In conclusion, the results demonstrated that steam treatment for 3 min could be the best optimal thermal pre-treatment condition for BP to minimize the quality changes.

열쾌적성과 NVOCs 배출량에 따른 겨울철 서귀포 치유의 숲의 최적 활동 시간 선정에 관한 연구

송도윤,안시옥,정다워,박범진 한국산림휴양복지학회 2022 한국산림휴양학회지 Vol.26 No.4

Forest activities in winter are thermally unpleasant and have been avoided because of the risk of injury. Jeju Island has a unique warm climate different from that of the Korean Peninsula, making it suitable for outdoor forest healing program activities in winter. It is necessary to select the optimal activity time for the safety of winter users and comfortable forest activities. This study aims to select the optimal activity time by measuring thermal comfort and NVOCs detection amount for each time in winter Seogwipo Healing Forest. The analysis showed that the thermal comfort was maintained from 10:00 to 14:00 compared to other periods. As a result of the NVOCs analysis, a total of 13 species were detected, and the detection amount was high from the third collection time(10:00~11:00) to the fifth collection time(12:26~13:26). Based on the thermal comfort analysis and NVOCs detection results, it was concluded that the time between 10:00 and 14:00 is the most suitable time for winter forest healing activities in Seogwipo Healing Forest. The results of this study can be used as data for the operation of winter forest healing programs in Seogwipo Healing Forest. It is also worth referring to when operating the Healing Forest in the southern region of the Korean Peninsula, which has a similar climate to Jeju Island. 겨울철 산림활동은 열적으로 불쾌적하고, 부상 위험성이 존재하여 기피되어왔다. 제주도는 한반도와 다른 특유의 온난한 기후로 겨울철 실외 산림치유프로그램 활동에 적합하다. 본 연구는 이용객의 안전과 쾌적한 산림 활동을 위하여 겨울철 서귀포 치유의 숲을 대상으로 열쾌적성과 NVOCs배출량을 시간별로 측정하여 최적 활동시간을 선정하는 것을 목적으로 한다. 열쾌적성 분석 결과, 다른 시간대에 비하여 10시부터 14시까지 열적으로 쾌적한 상태를 유지하였다. NVOCs 분석 결과, 총 13종이 검출되었으며, 세번째 포집시간(10:00~11:00)부터 다섯번째 포집시간(12:26~13:26)까지 높은 검출량을 보였다. 열쾌적성 분석과 NVOCs 검출 결과를 기반하여 겨울철 서귀포 치유의 숲은 오전 10시부터 14시까지의 시간대가 산림치유 활동에 있어 가장 적합한 시간대란 결과를 도출하였다. 본 연구 결과는 서귀포 치유의 숲의 겨울철 산림치유프로그램 운영에 있어 자료로 활용 가능하며, 제주도와 비슷한 기후를 가진 한반도 남부지방의 치유의 숲 운영 시 참고할만하다.

Antioxidant Activities of Tuna Hydrolysates Obtained from Microbial and Acid-thermal Hydrolysis

Se Young JUNG,Joong Kyun KIM 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10

Tuna is one of the most popular fish in the world, which occupies ~26% of seafood exports in Korea. As a preservable food, tuna cans are explosively purchased during COVID-19 pandemic. For this reason, the amount of tuna waste is gradually increasing, urging efficient means to solve the related environmental problems caused from this waste. As a means of reutilization tuna waste, we sought to extract bioactive peptides from tuna hydrolysates. To obtain the tuna hydrolysates, biodegradation was performed in a 2 L flask at 45°C for 72 h using a mixture of 11 species of protease-synthesizing Bacillus sp., resulting in 32.3% of hydrolysis. The highest antioxidant activity (92.3%) was obtained after 6-h biodegradation at the lowest pH (6.13). In parallel, tuna hydrolysates were obtained by acid-thermal hydrolysis. The acid-thermal hydrolysis was conducted at pH 1, followed by 20-min autoclaving. The resultant tuna hydrolysates exhibited 79.1% of antioxidant activity with 59.7% of hydrolysis. It has known that amino acids such as cysteine and methionine are completely destroyed by acid treatment, while amino acids such as tyrosine are partially destroyed. These amino acids are all contributors to antioxidant activity. Thus, this lower antioxidant activity might be caused by the damage of antioxidant-activity-contributing amino acids from the acid treatment. From the above results, microbial hydrolysis using protease-synthesizing microorganisms was concluded to have some advantages over acid-thermal hydrolysis, and thus increase in the degree of biodegradation would be critical to obtain diverse bioactive peptides.

Influence of Sulfur Fertilization on the Antioxidant Activities of Onion Juices Prepared by Thermal Treatment

Eunmi Koh,Jeonghee Surh 한국식품영양과학회 2016 Preventive Nutrition and Food Science Vol.21 No.2

Two onions (Sulfur-1 and Sulfur-4) cultivated with different sulfur applications were thermally processed to elucidate the effects of heat treatment on browning index and antioxidant activity. Sulfur-4 onion had higher sulfur content compared with the Sulfur-1 onion. After thermal processing, browning intensity was different between the two onions juices, with lower values observed for Sulfur-4 onion juice. This suggests that sulfur inhibits the Maillard browning reaction. The total reducing capacity of the juices increased at higher thermal processing temperatures; however, it was also lower in the Sulfur-4 onion juice. This suggests that the heat treatment of onions enhanced their antioxidant activity, but the effect was offset in the Sulfur-4 onion juice presumably due to higher sulfur content. This study indicates that sulfur, a core element for the functionality of onions, can decrease the antioxidant activity of thermally processed onions because of its potential as a Maillard reaction inhibitor.

Influence of Sulfur Fertilization on the Antioxidant Activities of Onion Juices Prepared by Thermal Treatment

고은미,서정희 한국식품영양과학회 2016 Preventive Nutrition and Food Science Vol.21 No.2

Two onions (Sulfur-1 and Sulfur-4) cultivated with different sulfur applications were thermally processed to elucidate the effects of heat treatment on browning index and antioxidant activity. Sulfur-4 onion had higher sulfur content compared with the Sulfur-1 onion. After thermal processing, browning intensity was different between the two onions juices, with lower values observed for Sulfur-4 onion juice. This suggests that sulfur inhibits the Maillard browning reaction. The total reducing capacity of the juices increased at higher thermal processing temperatures; however, it was also lower in the Sulfur-4 onion juice. This suggests that the heat treatment of onions enhanced their antioxidant activity, but the effect was offset in the Sulfur-4 onion juice presumably due to higher sulfur content. This study indicates that sulfur, a core element for the functionality of onions, can decrease the antioxidant activity of thermally processed onions because of its potential as a Maillard reaction inhibitor.

Influence of Sulfur Fertilization on the Antioxidant Activities of Onion Juices Prepared by Thermal Treatment

Koh, Eunmi,Surh, Jeonghee The Korean Society of Food Science and Nutrition 2016 Preventive Nutrition and Food Science Vol.21 No.2

Two onions (Sulfur-1 and Sulfur-4) cultivated with different sulfur applications were thermally processed to elucidate the effects of heat treatment on browning index and antioxidant activity. Sulfur-4 onion had higher sulfur content compared with the Sulfur-1 onion. After thermal processing, browning intensity was different between the two onions juices, with lower values observed for Sulfur-4 onion juice. This suggests that sulfur inhibits the Maillard browning reaction. The total reducing capacity of the juices increased at higher thermal processing temperatures; however, it was also lower in the Sulfur-4 onion juice. This suggests that the heat treatment of onions enhanced their antioxidant activity, but the effect was offset in the Sulfur-4 onion juice presumably due to higher sulfur content. This study indicates that sulfur, a core element for the functionality of onions, can decrease the antioxidant activity of thermally processed onions because of its potential as a Maillard reaction inhibitor.

Recycling of excess sludge using titanium tetrachloride (TiCl₄) as a flocculant aid with alkaline-thermal hydrolysis

Na, S.H.,Shon, H.K.,Kim, J.B.,Park, H.J.,Cho, D.L.,Saliby, I.E.,Kim, J.H. Korean Society of Industrial and Engineering Chemi 2010 Journal of industrial and engineering chemistry Vol.16 No.1

The highly strengthened treatment and disposal of excess sludge based on economic and environmental regulation factors is one of the important issues to be dealt with in the activated sludge process. In this study, the reduction and recycling technology of excess sludge were investigated for the aim of achieving a zero emission of excess sludge produced from the activated sludge process using titanium tetrachloride (TiCl<SUB>4</SUB>) as a flocculant aid with alkaline-thermal hydrolysis. Alkaline-thermal hydrolysis of excess sludge was obtained 73% and 40% reduction rate at pH 13 (60 8<SUP>o</SUP>C) and pH 11 (60 8<SUP>o</SUP>C), respectively. Flocculation was carried out using a Ti-salt flocculant and the collected sludge was dewatered and incinerated at 600<SUP>o</SUP>C to produce TiO<SUB>2</SUB> nanoparticles. The amount of total suspended solids and volatile suspended solids was significantly decreased with pH increase. The optimal dose of Ti-salt flocculation aid to improve dewatering ability of sludge breakage was 23.95Ti-mgl<SUP>-1</SUP>. Also, in the batch culture, the supernatant after flocculation and the organic matter released from the lysed sludge were found to be useful as a source of energy for the growth of microorganisms during the aerobic operations period. TiO<SUB>2</SUB> produced from Ti-salt flocculation of excess sludge (TES) was characterized by X-ray diffraction, scanning electron microscopy/energy dispersive X-ray and photocatalytic activity.

알루미나 골재 첨가에 따른 플라이애쉬-고로슬래그계 지오폴리머의 열적특성

김진호,남인탁,박현,김경남,Kim, Jin-Ho,Nam, In-Tak,Park, Hyun,Kim, Kyung-Nam 한국결정성장학회 2017 한국결정성장학회지 Vol.27 No.1

In this study, the higher temperature thermal property of the fly ash-blast furnace slag system Geopolymer including alumina aggregate was investigated whether that Geopolymer will be or not useful as thermal-resistant construction materials. Under every mixing conditions, the crack on the surface of hardened body was not observed up to $800^{\circ}C$ and it corresponded with fact that level of changes was not significant before and after heating process. Residual compressive strength is most high when mixing Blast-Furnace Slag ratio is 60 wt% until temperature reaches $800^{\circ}C$. The major hydrates of hardened body of Geopolymer; amorphous halo pattern between $20{\sim}35^{\circ}$ (2theta) and mullite ($3Al_2O_3{\cdot}2SiO_2$) and quartz ($SiO_2$) was found during the experiment. Amorphous halo pattern was a aluminosilicate gel generated by geopolymeric polycondensation and it was found that the halo pattern of aluminosilicate gel was preserved up to $800^{\circ}C$. The patterns of aluminosilicate gel disappeared from $1,000^{\circ}C$ and crystal phases like gehlenite, calcium silicate, calcium aluminum oxide, microcline was observed with the increase of exposure temperature. 본 연구에서는 Alumina 골재를 사용한 fly ash-blast furnace slag계 Geopolymer의 내열성 건축자재로서의 사용 가능성을 검토하기 위하여 고온조건에서의 열적 특성에 대하여 조사하였다. 모든 배합조건에서 Geopolymer 경화체의 표면 크랙은 $800^{\circ}C$까지는 관찰되지 않았으며, 이것은 열처리 전후 강도의 변화가 작은 것과 일치한다. 또한, $800^{\circ}C$까지 고로슬래그의 혼합비율이 60 wt%일 때 잔존압축강도가 가장 우수한 것으로 나타났다. Geopolymer 경화체의 주요 수화 생성물은 $20{\sim}35^{\circ}$(2theta) 범위의 비정질 halo 패턴과 원재료의 mullite($3Al_2O_3{\cdot}2SiO_2$)와 quartz($SiO_2$)가 확인되었다. 비정질 halo 패턴은 Geopolymer 축중합 반응에 의해서 생성된 aluminosilicate gel이며, $800^{\circ}C$까지는 aluminosilicate gel의 halo 패턴이 유지되고 있음을 알 수 있다. $1,000^{\circ}C$에서 aluminosilicate gel의 패턴은 사라지며 열처리온도의 증가와 함께 gehlenite, calcium silicate, calcium aluminum oxide, microcline와 같은 결정상이 관찰되었다.