Enhanced ionic mobility and increased efficiency of dye-sensitized solar cell by adding lithium chloride in poly(vinylidene fluoride) nanofiber as electrolyte medium

Sahito, I. A.,Ahmed, F.,Khatri, Z.,Sun, K. C.,Jeong, S. H. Springer Science + Business Media 2017 JOURNAL OF MATERIALS SCIENCE - Vol.52 No.24

沖縄における供犠の多様性

萩原左人(Hakiwara Sahito) 중앙대학교 한국문화유산연구소 2008 중앙민속학 Vol.- No.13

1. 공희에 대하여 2. 오키나와 공희의 사례 1) 촌락에 의한 공희-오키나와 섬 남부ㆍ이토카즈의 시마쿠사라사- 2) 친족집단에 의한 공희-오키나와 섬 북부ㆍ야베의 푸미차우가미- 3) 생업집단에 의한 공희-이케마 섬의 히다간니가이- 4) 가정ㆍ개인에 의한 공희-오키노에라부 섬의 와토토- 5) 장송의례에 의한 공희-오키나와 섬 북부ㆍ요나미네의 다비- 6) 시육(屍肉) 먹기에 관한 전승 3. 공희의 다양성 짐승 등을 의례적으로 도살하여 신령 등의 존재에게 바치는 행위를 일반적으로 ‘공희’(供犧, sacrifice)라고 한다. (이시카와 외, 1987) 공희는 영적인 존재와 인간을 연결시키기 위한 의례형식의 하나로 전 세계적으로 나타나는데, 그 내용은 실로 다양하다. 나카무라 이쿠오에 따르면 서구의 일신교적인 세계에서는 공희가 동물의 파괴(도살)와 피를 통해 신의 신성함을 강조하는 반면, 일본(본토 지역)의 공희에서는 도살이나 피가 갖는 의례적ㆍ상징적인 의미보다도 공식(共食)이 중요시되며, 이것을 통한 신과의 합일이 강조된다고 한다. 뿐만 아니라 일본에서는 벼를 신성히 여기는 농경 사회가 형성되는 과정에서 짐승을 도살하는 행위나 피라고 하는 것은 벼의 신성함과는 대치되는 것으로 여겨지게 되었으며, 그 결과 동물 공희보다도 벼(쌀)를 공식하는 의례가 현저하였음을 지적하였다. (나카무라, 2001) 나카무라가 설명하고 있는 것처럼, 실제로 일본의 본토 지역에서는 짐승을 도살하거나 공헌ㆍ공식하는 의례는 적다. 물론 수렵의례에서 야생동물을 신에게 바치는 예와 같은 것은 찾아볼 수 있지만, 일반적인 농촌에서 농경에 관여하는 가축을 대상으로 한 공희는 매우 적다고 할 수 있겠다. 한편 아마미(奄美)ㆍ오키나와(沖?)의 섬들을 살펴보면 위와 같은 일본 본토 지역의 상황과는 큰 차이가 나타난다. 앞에서 살펴본 것처럼 이들 섬 지역에서는 식용동물의 사육과 그 육식이 생활 속에 정착되어 있기 때문에 소나 돼지를 이용한 공희가 널리 행해지고 있는 것이다. 그리고 야마시타 긴이치에 의하면, 이 지역에는 ‘유타’라고 하는 민간의 종교적 직능자(샤먼)에 의한 주술적 행위로서의 공희뿐만 아니라 연중행사, 장송의례, 건축의례, 임시적인 방재의례 등 다양한 때에 공희가 행해져 왔다고 한다. (야마시타, 1977) 여기에서는 모든 종류의 공회에 대해 언급하기는 어렵기 때문에, 사료나 민속사례 중에 등장하는 몇 가지 공희들을 중심으로 살펴보고자 한다. 특히 민속사례의 경우, 일반적으로 사회집단(촌락ㆍ친족ㆍ가족이나 개인 등)에 따라 그 의례가 체계화되는 일이 많기 때문에 촌락ㆍ친족집단ㆍ생업집단ㆍ가족 및 개인 등 각각의 공희들을 사례로 들어보고자 한다. 이상에서 소개한 사례들을 통해 알 수 있는 것처럼 오키나와의 공희는 지극히 다양한 양상을 띠고 있으며, 각각의 의례 맥락에 따라서 이해될 필요가 있다. 그러나 공희 형식에 관해서 본다면, 각각의 의례에는 공통적인 요소가 포함되어 있다. 그럼, 마지막으로 공희의 다양성과 관련되는 형식상의 특징에 대해 짚어보기로 하자. 일반적으로 공희 의례는 대상 ①동물의 도살, ②신령에의 공헌, ③참여자들의 공식ㆍ향연 등으로 이루어진다. 이들은 지금까지 보아 온 모든 사례에서도 발견되는 요소들이라고 할 수 있겠다. 앞에서 지적한 바와 같이, 나카무라 이쿠오에 의하면 일본의 공희에서는 짐승의 도살이나 피를 통한 의례적이고 상징적인 의의보다도 공식이 중요시되며, 공식에 의한 신과의 합일이 강조되는 경향이 있다. 다시 말해 ①보다도 ②와 ③이 의례상 중시되고 있다는 뜻이 된다. 이 글에서 소개한 모든 사례들에서도 전체적으로 대개 그러한 경향을 확인할 수 있겠는데, 즉 어느 부분을 중요시하고 강조하는가에 따라서 의례의 다양성을 찾아볼 수 있는 것이다. 사례 1의 경우, 피나 썩는 냄새 등이 중요한 역할을 하고 있다. 이것은 죽음의 상태를 상징적으로 나타냄으로써 외부로부터의 재액과 단절을 꾀하는 것이라고 생각할 수 있는데, 즉 ①의 요소가 특징적으로 나타나는 사례라고 볼 수 있겠다. 사례 2나 사례 3의 경우, 조상에게 소를 보여주는 행위나 용궁으로 돼지를 보내는 행위가 의례화되어 있으며, 이것은 제사 드리는 대상에게 동물이나 고기 요리를 제물로 바친다고 하는 ②의 요소가 중시되는 사례들이라고 볼 수 있다. 또한 사례 4와 같이 동물이 인간을 ‘대신’하는 역할을 하는 경우, ①(대신 죽는 것), 혹은 ②(대신 제물로서 바쳐지는 것)의 요소가 중시되고 있는 것이라고 해석할 수 있겠다. ③은 모든 사례들에서 공통적으로 나타나는 요소이며, ②와 연동하여 제물의 ‘우산데(제상에서 물린 음식을 뜻하는 ‘제퇴선’)를 함께 먹고(공식), 즐기는(향연) 형식을 취하는 경우가 많다. 이러한 의미에서 ③의 행위에 특별한 의미를 부여하고 있는 것이 사례 5와 6이라고 할 수 있겠다.

Spindle Speed Optimization of a Ring Spinning Machine for Better Surface Irregularity and Hairiness of Yarn and Fabric

정성훈,Sahito, Iftikhar Ali,Arbab, Alvira Ayoub,Jeong, Sung Hoon 한국섬유공학회 2015 한국섬유공학회지 Vol.52 No.1

Producing yarn from natural fibers without creating irregularities in structure or having fibers protruding from the surface, remains the goal of spinners. This is a problem, as structural irregularities such as hairiness affect subsequent fabric manufacturing processes and the aesthetics of the final fabric. This work therefore focused on investigating the effects of varying the spindle speed of a ring spinning frame on the structure of yarn (i.e., its surface regularity and hairiness), its strength and the surface pilling of fabric made from such yarn with a view to optimizing the spindle speed. For this, yarns with counts of 20, 25, and 30 tex were produced at six different spindle speeds ranging from 11,000 to 21,000 rpm with an interval of 2,000 rpm. All other parameters were kept constant, including the draft for a particular count, the type and weight of the traveler, and the diameter of the ring. The results obtained revealed that as the spindle speed was increased to 17,000 rpm, the yarn structure became more regular and less hairy, thereby becoming stronger. Beyond 17,000 rpm, however, both the regularity and strength decreased, with the hairiness continuing to increase with increasing spindle speed. Consequently, the surface pilling of the fabric was found to be optimized when made from yarns produced at a spindle speed of 17,000 rpm.

Fabrication of a flexible and conductive lyocell fabric decorated with graphene nanosheets as a stable electrode material

Mengal, N.,Sahito, I.A.,Arbab, A.A.,Sun, K.C.,Qadir, M.B.,Memon, A.A.,Jeong, S.H. Applied Science Publishers ; Elsevier Science Ltd 2016 Carbohydrate polymers Vol.152 No.-

Textile electrodes are highly desirable for wearable electronics as they offer light-weight, flexibility, cost effectiveness and ease of fabrication. Here, we propose the use of lyocell fabric as a flexible textile electrode because of its inherently super hydrophilic characteristics and increased moisture uptake. A highly concentrated colloidal solution of graphene oxide nanosheets (GONs) was coated on to lyocell fabric and was then reduced in to graphene nanosheets (GNs) using facile chemical reduction method. The proposed textile electrode has a very high surface conductivity with a very low value of surface resistance of only 40Ωsq<SUP>-1</SUP>, importantly without use of any binding or adhesive material in the processing step. Atomic force spectroscopy (AFM) and Transmission electron microscopy (TEM) were conducted to study the topographical properties and sheet exfoliation of prepared GONs. The surface morphology, structural characterization and thermal stability of the fabricated textile electrode were studied by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), X ray photon spectroscopy (XPS), Raman spectroscopy, Wide angle X ray diffraction spectroscopy (WAXD) and Thermogravimetric analysis (TGA) respectively. These results suggest that the GONs is effectively adhered on to the lyocell fabric and the conversion of GONs in to GNs by chemical reduction has no adverse effect on the crystalline structure of textile substrate. The prepared graphene coated conductive lyocell fabric was found stable in water and electrolyte solution and it maintained nearly same surface electrical conductivity at various bending angles. The electrical resistance results suggest that this lyocell based textile electrode (L-GNs) is a promising candidate for flexible and wearable electronics and energy harvesting devices.

Highly efficient and durable dye-sensitized solar cells based on a wet-laid PET membrane electrolyte

Sun, Kyung Chul,Sahito, Iftikhar Ali,Noh, Jung Woo,Yeo, Sang Young,Im, Jung Nam,Yi, Sung Chul,Kim, Yeon Sang,Jeong, Sung Hoon The Royal Society of Chemistry 2016 Journal of Materials Chemistry A Vol.4 No.2

<▼1><P>Polyethylene terephthalate (PET), a commonly used textile fiber, was used in the form of a wet-laid non-woven fabric as a matrix for electrolytes in dye-sensitized solar cells (DSSCs).</P></▼1><▼2><P>Polyethylene terephthalate (PET), a commonly used textile fiber, was used in the form of a wet-laid non-woven fabric as a matrix for electrolytes in dye-sensitized solar cells (DSSCs). Also functioning as a separator between the photoanode and cathode of a DSSC, this non-woven membrane was prepared by a well-known wet-laid manufacturing process followed by calendaring to reduce the thickness and increase the uniformity of the structure. This membrane can better absorb the electrolyte turning into a quasi-solid, providing excellent interfacial contact between both electrodes of the DSSC and preventing a short circuit. An optimized membrane provides a better and more desirable structure for ionic conductivity, resulting in the improvement of the photovoltaic performance after calendaring. The quasi-solid-state DSSC assembled with an optimized membrane exhibited 10.248% power conversion efficiency (PCE) at 100 mW cm<SUP>−2</SUP>. With the aim of increasing the absorbance, the membrane was also plasma-treated with argon and oxygen separately, which resulted in retention of the electrolyte, avoiding its evaporation, and a 15% longer lifetime of the DSSC compared to liquid electrolytes. The morphology of the membrane was studied by field emission scanning electron microscopy, and the photovoltaic properties and impedance spectroscopy of the cells were studied using polarization curves and electrochemical impedance spectroscopy, respectively. The results suggest that this novel membrane can be used in high-efficiency solar cells, increasing their lifetime without compromising the photovoltaic properties.</P></▼2>

Shared molecular basis, diagnosis, and co-inheritance of alpha and beta thalassemia

Govinda Khatri,Abdul Moiz Sahito,Saboor Ahmed Ansari 대한혈액학회 2021 Blood Research Vol.56 No.4

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Self-assembled nitrogen-doped graphene quantum dots (N-GQDs) over graphene sheets for superb electro-photocatalytic activity

Riaz, Rabia,Ali, Mumtaz,Sahito, Iftikhar Ali,Arbab, Alvira Ayoub,Maiyalagan, T.,Anjum, Aima Sameen,Ko, Min Jae,Jeong, Sung Hoon Elsevier BV * North-Holland 2019 Applied Surface Science Vol.480 No.-

<P><B>Abstract</B></P> <P>Nitrogen-doped graphene quantum dots (N-GQDs) are emerging electroactive and visible light active organic photocatalysts, known for their high stability, catalytic activity and biocompatibility. The edge surfaces of N-GQDs are highly active, however, when N-GQDs make the film the edges are not fully exposed for catalysis. To avoid this issue, the N-GQDs are shaped to branched leaf shape, with an extended network of voids, offering highly active surfaces (edge) exposed for electrocatalytic and photocatalytic activity. The nitrogen doping causes a decrease in the bandgap of N-GQDs, thus enabling them to be superb visible light photocatalyst, for degradation of Methylene blue dye from water. Photoluminescence results confirmed that by a synergistic combination of the highly conductive substrate; Carbon fabric coated graphene sheets (CF-rGO) the recombination of photogenerated excitons is significantly suppressed, hence enabling their efficient utilization for catalysis. Comparatively, uniformly coated N-GQDs showed 49.3% lower photocatalytic activity, owing to their hidden active sites. The degradation was further boosted by 30% by combining the electrocatalytic activity, i.e. electro-photocatalysis of the proposed electrode. The proposed electrode material was analyzed using TEM, FE-SEM, FTIR, AFM, and WA-XRD, whereas the stability of electrode was confirmed by TGA, tensile test, bending test, and in harsh chemical environments. The proposed photo-electrocatalyst electrode is binder-free, stable, flexible and highly conductive, which makes the electrode quite suitable for flexible catalytic devices like flexible solar cells and wearable supercapacitors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A flexible electrode is fabricated using self-assembled overlayer of Nitrogen doped Graphene Quantum Dots (N-GQDs). </LI> <LI> Self-assembeled highly porous leaflets structure has maximum exposed edge surfaces to accelarate the catalytic reaction. </LI> <LI> The proposed electrode is metal free and is stable at high temperature, harsh chemical environments, and mechanical stresses. </LI> <LI> The surface resistance of the all carbon electrode is only 2.5 Ω sq.<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Nitrogen doped graphene quantum dots (N-GQDs) were self-assembled (with high porosity) on reduced graphene oxide coated carbon fabric to fabricate a highly stable visible light photocatlytically and electrocatalytically active flexible electrode for water treatment.</P> <P>[DISPLAY OMISSION]</P>

난카이 해구 지진해일이 한반도 연안에 미치는 영향

김샛별(SatByul Kim),Tatsuhiko Sahito,Eiichi Fukuyama,강태섭(Tae-Seob Kang) 대한지질학회 2017 대한지질학회 학술대회 Vol.2017 No.10

An electrocatalytic active lyocell fabric cathode based on cationically functionalized and charcoal decorated graphite composite for quasi-solid state dye sensitized solar cell

Mengal, Naveed,Arbab, Alvira Ayoub,Sahito, Iftikhar Ali,Memon, Anam Ali,Sun, Kyung Chul,Jeong, Sung Hoon Elsevier 2017 SOLAR ENERGY -PHOENIX ARIZONA THEN NEW YORK- Vol.155 No.-

<P><B>Abstract</B></P> <P>The state of the art of conductive functional textile woven fabrics have given rise to a demand for textile integrated electrodes. Herein, we report a highly conductive and flexible woven fabric electrode using highly absorbent lyocell fabric as the substrate and cationically functionalized and activated charcoal decorated graphite composite (AC-GC) as the coating film. This (AC-GC) coated lyocell fabric is used as a cathode for quasi-solid state dye sensitized solar cell (Q-DSSCs). Our suggested fabric based cathode shows sufficiently high conductivity and electrocatalytic activity (ECA) compared to platinum (Pt) based reference counter electrode (CE). This efficient CE demonstrates extremely low charge transfer resistance (R<SUB>CT</SUB>) of 1.56Ωcm<SUP>2</SUP> with polyethylene oxide based quasi-solid electrolyte. The cationic charged enriched charcoal decorated graphite planner structure provide more availability of active sites for the reduction of negatively charged tri-iodide ( I 3 - ) ions present in polymeric gel electrolyte. The formation of porous charcoal voids and conductive graphite channels entrap large amounts of gel electrolyte and provide fast diffusion of iodide/tri-iodide ( <SUP> I - </SUP> / I 3 - ) ions. Our organic system of AC-GC coated lyocell fabric based DSSCs assembly demonstrated 7.09% power conversion efficiency (PCE) when fabricated with quasi-solid electrolyte. This AC-GC coated fabric CE is also highly stable in water and electrolyte solution. The adequate electrocatalytic activity and cyclic stability demonstrate that this AC-GC coated fabric can be used to replace expensive Pt CE and can be used in flexible solar cells in future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Various composites of activated charcoal and enzyme functionalized graphite (AC-GC) were prepared by a facile route. </LI> <LI> Highly porous and electrocatalytic AC-GC coatings were applied on lyocell fabric for preparation of flexible electrode. </LI> <LI> The flexible electrodes showed high stability in water and lithium iodide based electrolyte. </LI> <LI> DSSC based on optimized flexible electrode demonstrated maximum power conversion efficiency of 7.09%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Cationic functionalized and activated charcoal decorated graphite coated lyocell fabric cathode is Q-DSSCs, displayed 7.1% efficiency.</P> <P>[DISPLAY OMISSION]</P>

Facile fabrication of activated charcoal decorated functionalized multi-walled carbon nanotube electro-catalyst for high performance quasi-solid state dye-sensitized solar cells

Memon, A.A.,Arbab, A.A.,Sahito, I.A.,Mengal, N.,Sun, K.C.,Qadir, M.B.,Choi, Y.S.,Jeong, S.H. Pergamon Press 2017 ELECTROCHIMICA ACTA Vol.234 No.-

<P>The proposed research presents significant progress in the photovoltaic performance of quasi-solid state dye-sensitized solar cells (DSSCs) by synthesizing a highly electro-catalytic active activated charcoal decorated functionalized multi-walled carbon nanotube (MWCNT) composite electro-catalyst as a counter electrode (CE). The proposed carbon composite structure was synthesize by facile acid functionalization of MWCNTs followed by the addition of mesoporous activated charcoal, decorating the tubular graphitic structure of the CNTs. The carbon composite paste deposited on FTO glass by a sequential process of doctor blade coating under an air-drying technique. The porous functionalized mesoporous carbon (f-MC) with a dominant oxygen rich surface displays greatly enhanced electrocatalytic activity, low charge transfer resistance (RCT), and exceptional cyclic stability as compared with pristine CNTs. The DSSC fabricated with f-MC CE demonstrated efficient electrochemical characteristics and photovoltaic performance when fabricated with a high-viscosity quasi-solid electrolyte. The highly conductive and porous carbon structure locates manifold sites for tri-iodide reduction reaction. High mobility of the quasi-solid electrolyte within defect rich (f-MC) surface confirmed a low RCT of (0.60 Omega. cm(2)), and exhibited superior electrocatalytic activity compared to a conventional platinum (Pt) reference CE. The f-MC CE based DSSCs showed high power conversion efficiency (PCE) of 8.42%, exceeding the Pt reference CE of 8.11%. Based on the facile synthesis of f-MC composites and fabrication of CE, the proposed DSSCs stand out as efficient next generation solar cells. (C) 2017 Elsevier Ltd. All rights reserved.</P>