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박권하,R. Prosser 한국동력기계공학회 2023 동력시스템공학회지 Vol.27 No.3
Regulations on carbon dioxide emitted from ships have been strengthened, and technologies for low-carbon or carbon-free fuel have been developed. However, marine engines currently operating on heavy fueled oil are expected to continue to be used. Therefore, it is necessary to continue research on the performance improvement of marine diesel engines using heavy fueled oil. This study analyzed the effects of exhaust gas recirculation (EGR) on combustion behaviors. The effect of EGR on the combustion process such as fuel, flame, temperature, and combustion products behavior in the combustion chamber was analyzed. The emission of nitrogen oxides is reduced exponentially with the increase of the EGR rate. However, when the EGR rate increases, the propagation distance of the fuel spray increases and a large amount of fuel is distributed on the lower surface of the chamber in a low temperature state with the increase of the EGR rate. Therefore, the amount of unburned fuel is greatly increased up to 13.3%. Considering both energy efficiency and other emissions, it is desirable to keep the EGR rate below 23%. 선박에서 배출되는 이산화탄소에 대한 규제가 강화되고 저탄소 또는 무탄소 연료에 대한 기술이 개발되고 있다. 그러나 현재 중유로 작동하는 선박용 디젤엔진은 계속 사용될 것으로 예상되며 중유를 이용한 선박용 디젤엔진의 성능향상에 대한 연구가 지속되어야 한다. 본 연구에서는 배기가스재순환기술(EGR)이 연소거동에 미치는 영향을 분석하였다. 연소실에서 연료, 화염, 온도 및 연소 생성물 거동과 같은 연소과정에 대한 EGR의 영향을 분석하였다. 질소산화물 배출은 EGR 비율이 증가함에 따라 기하급수적으로 감소된다. 그러나 EGR율이 증가하면 연료분무의 전파거리가 증가하고 저온상태에서 다량의 연료가 연소실 하부면에 분포하게 되면서 미연소 연료량은 13.3%까지 크게 증가한다. 에너지 효율과 기타 배출가스를 종합적으로 고려할 때 EGR율은 23% 이하로 유지하는 것이 바람직하다.
Bragg stack-functionalized counter electrode for solid-state dye-sensitized solar cells.
Park, Jung Tae,Prosser, Jacob H,Kim, Dong Jun,Kim, Jong Hak,Lee, Daeyeon Wiley-VCH 2013 CHEM SUS CHEM Vol.6 No.5
<P>A highly reflective counter electrode is prepared through the deposition of alternating layers of organized mesoporous TiO(2) (om-TiO(2)) and colloidal SiO(2) (col-SiO(2)) nanoparticles. We present the effects of introducing this counter electrode into dye-sensitized solar cells (DSSCs) for maximizing light harvesting properties. The om-TiO(2) layers with a high refractive index are prepared by using an atomic transfer radical polymerization and a sol-gel process, in which a polyvinyl chloride-g-poly(oxyethylene) methacrylate graft copolymer is used as a structure-directing agent. The col-SiO(2) layers with a low refractive index are prepared by spin-coating commercially available silica nanoparticles. The properties of the Bragg stack (BS)-functionalized counter electrode in DSSCs are analyzed by using a variety of techniques, including spectroscopic ellipsometry, SEM, UV/Vis spectroscopy, incident photon-to-electron conversion efficiency, electrochemical impedance spectroscopy, and intensity modulated photocurrent/voltage spectroscopy measurements, to understand the critical factors contributing to the cell performance. When incorporated into DSSCs that are used in conjunction with a polymerized ionic liquid as the solid electrolyte, the energy conversion efficiency of this solid-state DSSC (ssDSSC) approaches 6.6 %, which is one of the highest of the reported N719 dye-based ssDSSCs. Detailed optical and electrochemical analyses of the device performance show that this assembly yields enhanced light harvesting without the negative effects of charge recombination or electrolyte penetration, which thus, presents new possibilities for effective light management.</P>
Park, Jung Tae,Prosser, Jacob H.,Ahn, Sung Hoon,Kim, Sang Jin,Kim, Jong Hak,Lee, Daeyeon WILEY‐VCH Verlag 2013 Advanced Functional Materials Vol.23 No.17
<P><B>Abstract</B></P><P>High efficiency dye‐sensitized solar cells (DSSCs) are fabricated with a heterostructured photoanode that consists of a 500‐nm‐thick organized mesoporous TiO<SUB>2</SUB> (om‐TiO<SUB>2</SUB>) interfacial layer (IF layer), a 7 or 10‐μm thick nanocrystalline TiO<SUB>2</SUB> layer (NC layer), and a 2‐μm‐thick mesoporous Bragg stack (meso‐BS layer) as the bottom, middle and top layers, respectively. An om‐TiO<SUB>2</SUB> layer with a high porosity, transmittance, and interconnectivity is prepared via a sol‐gel process, in which a poly(vinyl chloride)‐<I>g</I>‐poly(oxyethylene methacrylate) (PVC‐<I>g</I>‐POEM) graft copolymer is used as a structure‐directing agent. The meso‐BS layer with large pores is prepared via alternating deposition of om‐TiO<SUB>2</SUB> and colloidal SiO<SUB>2</SUB> (col‐SiO<SUB>2</SUB>) layers. Structure and optical properties (refractive index) of the om‐TiO<SUB>2</SUB> and meso‐BS layers are studied and the morphology of the heterostructured photoanode is characterized. DSSCs fabricated with the heterostructured IF/NC/BS photoanode and combined with a polymerized ionic liquid (PIL) exhibit an energy conversion efficiencies of 6.6% at 100 mW/cm<SUP>2</SUP>, one of the highest reported for solid‐state DSSCs and much larger than cells prepared with only a IF/NC layer (6.0%) or a NC layer (4.5%). Improvements in energy conversion efficiency are attributed to the combination of improved light harvesting, decreased resistance at the electrode/electrolyte interface, and excellent electrolyte infiltration.</P>
Multisite phosphorylation of C-Nap1 releases it from Cep135 to trigger centrosome disjunction
Hardy, Tara,Lee, Miseon,Hames, Rebecca S.,Prosser, Suzanna L.,Cheary, Donna-Marie,Samant, Mugdha D.,Schultz, Francisca,Baxter, Joanne E.,Rhee, Kunsoo,Fry, Andrew M. The Company of Biologists 2014 Journal of cell science Vol.127 No.11
<P><B>ABSTRACT</B></P><P>During mitotic entry, centrosomes separate to establish the bipolar spindle. Delays in centrosome separation can perturb chromosome segregation and promote genetic instability. However, interphase centrosomes are physically tethered by a proteinaceous linker composed of C-Nap1 (also known as CEP250) and the filamentous protein rootletin. Linker disassembly occurs at the onset of mitosis in a process known as centrosome disjunction and is triggered by the Nek2-dependent phosphorylation of C-Nap1. However, the mechanistic consequences of C-Nap1 phosphorylation are unknown. Here, we demonstrate that Nek2 phosphorylates multiple residues within the C-terminal domain of C-Nap1 and, collectively, these phosphorylation events lead to loss of oligomerization and centrosome association. Mutations in non-phosphorylatable residues that make the domain more acidic are sufficient to release C-Nap1 from the centrosome, suggesting that it is an increase in overall negative charge that is required for this process. Importantly, phosphorylation of C-Nap1 also perturbs interaction with the core centriolar protein, Cep135, and interaction of endogenous C-Nap1 and Cep135 proteins is specifically lost in mitosis. We therefore propose that multisite phosphorylation of C-Nap1 by Nek2 perturbs both oligomerization and Cep135 interaction, and this precipitates centrosome disjunction at the onset of mitosis.</P>
Chewing Lice of Swan Geese (Anser cygnoides)
Chang-Yong Choi,John Y. Takekawa,Diann J. Prosser,Lacy M. Smith,Craig R. Ely,Anthony D. Fox,Lei Cao,Xin Wang,Nyambayar Batbayar,Tseveenmayadag Natsagdorj,Xiangming Xiao 대한기생충학열대의학회 2016 The Korean Journal of Parasitology Vol.54 No.5
Chewing lice (Phthiraptera) that parasitize the globally threatened swan goose Anser cygnoides have been long recognized since the early 19th century, but those records were probably biased towards sampling of captive or domestic geese due to the small population size and limited distribution of its wild hosts. To better understand the lice species parasitizing swan geese that are endemic to East Asia, we collected chewing lice from 14 wild geese caught at 3 lakes in northeastern Mongolia. The lice were morphologically identified as 16 Trinoton anserinum (Fabricius, 1805), 11 Ornithobius domesticus Arnold, 2005, and 1 Anaticola anseris (Linnaeus, 1758). These species are known from other geese and swans, but all of them were new to the swan goose. This result also indicates no overlap in lice species between older records and our findings from wild birds. Thus, ectoparasites collected from domestic or captive animals may provide biased information on the occurrence, prevalence, host selection, and host-ectoparasite interactions from those on wild hosts.
Shape changing thin films powered by DNA hybridization
Shim, Tae Soup,Estephan, Zaki G.,Qian, Zhaoxia,Prosser, Jacob H.,Lee, Su Yeon,Chenoweth, David M.,Lee, Daeyeon,Park, So-Jung,Crocker, John C. Nature Publishing Group, a division of Macmillan P 2017 Nature nanotechnology Vol.12 No.1
<P>Active materials that respond to physical(1-3) and chemical(4-6) stimuli can be used to build dynamic micromachines that lie at the interface between biological systems and engineered devices(7,8). In principle, the specific hybridization of DNA can be used to form a library of independent, chemically driven actuators for use in such microrobotic applications and could lead to device capabilities that are not possible with polymer- or metal-layer-based approaches. Here, we report shape changing films(9) that are powered by DNA strand exchange reactions with two different domains that can respond to distinct chemical signals. The films are formed from DNA-grafted gold nanoparticles(10,11) using a layer-by-layer deposition process. Films consisting of an active and a passive layer show rapid, reversible curling in response to stimulus DNA strands added to solution. Films consisting of two independently addressable active layers display a complex suite of repeatable transformations, involving eight mechanochemical states and incorporating self-righting behaviour.</P>