Preparation of PVdF/GO Nanofiber Composite Membranes and its Heavy Metal Removal Characteristics

Hwakyung Jeong(정화경),Wongi Jang(장원기),Jaehan Yun(윤재한),Hongsik Byun(변홍식) 한국고분자학회 2016 폴리머 Vol.40 No.3

본 연구에서는 전기방사법을 이용하여 PVdF/GO 나노섬유 복합분리막을 제조하고, 중금속(납, 카드뮴)이온에 대한 제거특성평가를 진행하였다. 합성된 GO 및 복합분리막은 SEM, FTIR, Raman 분석 및 tensometer를 이용하여 특성평가를 진행하였으며, 위 결과로부터 다양한 기능기를 가진 GO의 합성 및 PVdF 나노섬유 내에 복합화되어 있는 것을 확인하였다. 또한 합성된 GO의 Langmuir 및 Freundlich 흡착 등온선 연구를 실시하였다. PVdF/GO 나노섬유 복합분리막은 친수특성을 보여주고 있으며, PVdF 나노섬유 분리막 대비 최대 3배 이상의 높은 수투과도를 나타내었다. PVdF/GO20의 중금속 제거율은 시간에 따라 점차 증가하였으며, 2시간 이후 95.2% (Pb), 98.3% (Cd)에 각각 도달하는 것을 확인하였다. 위 결과로부터 제조된 PVdF/GO 나노섬유 복합분리막은 하폐수처리 시스템에 충분히 활용할 수 있을 것으로 판단된다. This paper describes the preparation of PVdF/graphene oxide (GO) nanofiber composite membranes via electrospining and their removal characteristics of heavy metal ions (e.g., lead and cadmium). The synthesized GO and composite membranes were characterized by SEM, FTIR, Raman analysis, and tensometry. These results demonstrated the successful synthesis of GO with various functional groups and their incorporation into the PVdF nanofibers. In addition, the adsorption isotherm studies of the synthesized GO using both the Langmuir and Freundlich models were carried out. The PVdF/GO nanofiber composite membranes showed hydrophilic characteristics and higher pure water flux (up to 3 times) than that of a neat PVdF nanofiber membranes. The heavy removal rate of PVdF/GO20 increased gradually as a function of time which reached at 95.2% (Pb) and 98.3% (Cd) after 2 h, respectively. From these results, prepared PVdF/GO nanofiber composite membranes have shown a great potential to be utilized for the wastewater system.

Effect of host genetic background on the offspring sex ratio in the Wolbachia infected Trichogramma kaykai

Hwakyung Hwang,Yikweon Jang,Gilsang Jeong 한국응용곤충학회 2011 한국응용곤충학회 학술대회논문집 Vol.2011 No.05

The α-proteobacterium Wolbachia pipientis infects a wide range of arthropods and filarial nematodes. Wolbachia is maternally inherited and is known to induce reproductive anomalies such as cytoplasmic incompatibility, feminization, male killing and parthenogenesis induction (PI). Trichogramma kaykai is a tiny wasp that parasitizes on lepidopteran eggs. When a female of the wasp is infected with PI-Wolbachia, the female produces female offspring via gamete duplication without the aid of sperm. As she ages, however, the fraction of male offspring increases. In this study, we investigated the effect of host genetic background on the expression of sex ratio between isofemale lines. Virgin females of six isofemale lines were allowed to lay eggs individually for 10 days. There was the positive relationship between female age and the offspring sex ratio. Furthermore, the sex ratio was significantly different among isofemale lines, implying that the host genetic background had an effect on the sex ratio. Based on the results, evolution of symbiosis in terms of sex ratio and future experimental design are discussed.

Effects of host genetic backgrounds and the offspring sex ratio in the Wolbachia infected Trichogramma wasps

Hwakyung Hwang,Yikweon Jang,Gilsang Jeong 한국응용곤충학회 2011 한국응용곤충학회 학술대회논문집 Vol.2011 No.10

The α-proteobacterium Wolbachia is maternally inherited and is known to induce reproductive distortions in a wide range of insect taxa such as cytoplasmic incompatibility, feminization, male killing and parthenogenesis (PI). When a female is infected with PI-Wolbachia, she does not need a male to produce female offspring, because the female can produce female offspring via gamete duplication without the aid of sperm. However, in the parasitoid wasp Trichogramma kaykai species, Wolbachia infected parthenogenetic females still produce a fraction of male offspring. Offspring sex ratio for 10 days are different according to each T. kaykai isofemale line that is infected with PI- Wolbachia. This may be caused by complex interactions between Wolbachia and the host genetic backgrounds on converting sex of infected eggs.

Male Density Effect on Mating Behavior and Offspring Sex Ratio in Trichogramma Wasps (Hymenoptera: Trichogrammatidae)

Hwakyung Hwang,Yiseul Noh,Jinyoung Kim,Yeonsun Jeon,Soyeon Park,Pureum Noh,Bitna Lee,Injung Kim,Soyeong Lim,Yikweon Jang,Gilsang Jeong 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.04

In Hymenoptera, thanks to its haplodiploid sex determination, arrhenotokous parasitoid females are able to control offspring sex ratio by determining whether to use sperm or not at the time of oviposition. However, the offspring sex ratio may also be influenced by the mating behavior of a male. When a male searches females, he will have more chances to encounter with other males in a high male density population than low male density population. If the male is competitive, the male can find females faster and may have longer copulation time, and eventually transfer more sperm than other males. In this study, we investigated mate searching time, copulation duration and offspring sex ratio as a function of the male density. Although the results show difference between searching time and copulation duration, they are not statistically significant. We will discuss the statistical consequence, male density dependent offspring sex ratio and its evolutionary implications.

Microbiome of Two Morphs of Vollenhovia emeryi (Hymenoptera: Myrmicinae)

Gilsang Jeong,Soyeon Park,Pureum Noh,Seung-Yoon Oh,Hwakyung Hwang,Bitna Lee,Yongwhan Kim,Jae Chun Choe 한국응용곤충학회 2013 한국응용곤충학회 학술대회논문집 Vol.2013 No.04

The hologenome theory of evolution proposes that an organism is simply not an individual but the totality of numerous microbial symbionts to the host. In fact, the evidence of biochemical and physiological associations between the symbionts and the host has been growing fast in all major taxa. The Vollenhovia emeryi ant is tiny and found nationwide in Korea. The ant can be further categorized by its wing morphology, eg. long-winged and short-winged. Our initial screening process showed that the microbial reproductive manipulator, the Wolbachia bacterium, only infected the long-winged morph. This gave us a good opportunity to investigate the effect of the Wolbachia infection on the bacterial community diversity using the next generation sequencing technique. We find that there are about 180 bacterial symbionts in the short-winged morph. On the other hand, the long-winged morph has only about 20 bacterial symbionts. This implies that the bacterial community diversity may be subject to the existence of Wolbachia. Furthermore, the Wolbachia strain diversity is unexpectedly high. In addition, the bacterial structure difference among castes indicates that there may be labour division even between queens. The results and future research direction will be discussed from the hologenome theory perspective.

산업 무선 센서 네트워크에서 긴급 상황의 데이터 수집 지연시간 감소를 위한 TDMA 분산 슬롯 스케줄링 기법

이화경(Lee Hwakyung),정상화(Chyng Sang-Hwa),정익주(Jeong Ikjoo) 한국통신학회 2014 한국통신학회 학술대회논문집 Vol.2014 No.1

Three-dimensional Printing of Silver Microarchitectures Using Newtonian Nanoparticle Inks

Lee, Sanghyeon,Kim, Jung Hyun,Wajahat, Muhammad,Jeong, Hwakyung,Chang, Won Suk,Cho, Sung Ho,Kim, Ji Tae,Seol, Seung Kwon American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.22

<P>Although three-dimensional (3D) printing has recently emerged as a technology to potentially bring about the next industrial revolution, the limited selection of usable materials restricts its use to simple prototyping. In particular, metallic 3D printing with submicrometer spatial resolution is essential for the realization of 3D-printed electronics. Herein, a meniscus-guided 3D printing method that exploits a low-viscosity (similar to 7 mPa.s) silver nanoparticle (AgNP) ink meniscus with Newtonian fluid characteriftics (which is compatible with conventional inkjet printers) to fabricate 3D silver microarchitectures is reported. Poly(acrylic acid)-capped AgNP ink that exhibits a continuous ink flow through a confined nozzle without aggregation is designed in this study. Guiding the ink meniscus with controlled direction and speed enables both vertical pulling and layer-by-layer processing, resulting in the creation of 3D microobjects with designed shapes other than those for simple wiring. Various highly conductive (>10(4) S.cm(-1)) 3D metallic patterns are demonstrated for applications in electronic devices. This research 18 expected to widen the range of Materials that can be employed in 3D printing technology, with the aim of moving 3D printing beyond prototyping and into real manufacturing platforms for future electronics.</P>

유해화학물질 운반자의 취급안전보건 관리를 고려한 취급기준 마련 : 유해화학물질 시약 등 택배 안전용기 및 포장기준을 중심으로

임지영(JiYoung Im),정재형(JaeHyeong Jeong),성화경(HwaKyung Sung),권용민(YongMin Kwon),류지성(JiSung Ryu),이진홍(JinHong Lee),이지호(JiHo Lee) 한국환경보건학회 2020 한국환경보건학회지 Vol.46 No.4

Objectives: In this study, we analyzed the current state of delivery containers and packages and established handling guidelines to safely transport delivery containers and packages for use in research, testing, and examination reagents. Methods: Handling guidelines were revised in such categories as maintenance of the handling facilities, storage, loading and unloading, containers and packages, transportation, etc. In addition, we analyzed the current state of domestic sales for hazardous chemicals used for research, testing, and examination reagents, and investigated the handling guidelines related to delivery transportation in the USA, EU, and Japan by chemical property. Results: There are 6,160 companies selling hazardous chemicals. Among them, the 476 companies selling reagents for use in research, testing, and examination were investigated. Total amounts handled reached 425,000 tons, contributing to 0.2% of the total. For delivery transportation, internal containers and packaging was specified for chemical properties as follows: within 1 L for flammable gas, within 5 L for flammable liquid, and within 18 L for others. In addition, the maximum size of the outer package was set within 130 cm for total length, width, and height, and no dimension of the packaging could exceed 60 cm. Sixty-four hazardous chemicals with explosiveness or acute inhalation toxicity were prohibited for delivery transportation. Conclusion: Specified handling guidelines for inner and outer containers as well as packaging were regulated for delivery transportation of hazardous chemicals used for reagents. In addition, 64 hazardous chemicals were prohibited for delivery transportation. These are designed to prevent transportation accidents involving hazardous chemicals for reagents and thus protect the safety and health of transporters who handle hazardous chemicals.

Three-Dimensional Printing of Highly Conductive Carbon Nanotube Microarchitectures with Fluid Ink

Kim, Jung Hyun,Lee, Sanghyeon,Wajahat, Muhammad,Jeong, Hwakyung,Chang, Won Suk,Jeong, Hee Jin,Yang, Jong-Ryul,Kim, Ji Tae,Seol, Seung Kwon American Chemical Society 2016 ACS NANO Vol.10 No.9

<P>Moving printed electronics to three dimensions essentially requires advanced additive manufacturing techniques yielding multi functionality materials and high spatial resolution. Here, we report the meniscus-guided 3D printing of highly conductive multiwall carbon nano tube (MWNT) microarchitectures that exploit rapid solidification of a fluid ink meniscus formed by pulling a micronozzle. To achieve high-quality printing with continuous ink flow through a confined nozzle geometry, that is, without agglomeration and nozzle dogging, we design a polyvinylpyrrolidone-wrapped MWNT ink with uniform dispersion and appropriate rheological properties. The developed technique can produce various desired 3D microstructures, with a high MWNT concentration of up to 75 wt % being obtained via post-thermal treatment. Successful demonstrations of electronic components such as sensing transducers, emitters, and radio frequency inductors are also described herein. We expect that the technique presented in this study will facilitate selection of diverse materials in 3D printing and enhance the freedom of integration for advanced conceptual devices.</P>

13C 및 15N 안정성 동위원소 비율 분석에 의한 원료의약품에서 에페드린 및 슈도에페드린의 기원 판별

백승경(SeungKyung Baeck),Tetsuo Nagano,최화경(HwaKyung Choi),정희선(HeeSun Chung),표명윤(MyungYun Pyo),정진일(JinIl Jeong),양원경(Wonkyang Yang),Yukiko Makino,장문희(MoonHee Jang) 대한약학회 2009 약학회지 Vol.53 No.5

The abuse of methamphetamine (MA) is one of the most serious drug abuses in Asia. And, the prevention of precursor production for abuse drug is one of the most effective drug control system. Isotope ratio analysis at natural abundance levels have been used to establish the environmental source or the geographic origin of various biological and nonbiological materials. Ephedrine, the precursor of MA, is produced by one of three methods; extraction from Ephedra plants, full chemical synthesis or via a semi-synthetic process involving the fermentation of sugar, followed by amination. We investigated the origin of ephedrine and pseudoephedrine based on the carbon and nitrogen values for nineteen pharmaceutical powder materials (PPMs) obtained from pharmaceutical company in Korea by stable isotope ratio mass spectrometry coupled to an elemental analyser (EA-IRMS). The carbon delta values for the ephedrine and pseudoephedrine were -24.21~-22.72 (mean=-23.72) ‰ and -23.79~-22.71 (mean=-23.48) ‰. The nitrogen delta values were 3.51~5.55 (4.43) ‰ and 2.24~8.22 (5.42) ‰. These results indicate that PPMs are semi-synthetic products. Therefore the origins of ephedrine (natural, semi-synthetic or synthetic) could be discriminated by using carbon and nitrogen stable isotope ratios. we are sure tat this stable isotope ratio analysis can discriminate the origins of precursors of methamphetamine.