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City systems research: from morphology to relationality and positionality
Nicholas A. Phelps 서울시립대학교 도시과학연구원 2021 도시과학국제저널 Vol.25 No.4
Making reference to the ‘old’ concept of megalopolis I glance back to identify a future research agenda on city systems. Megalopolis happens to be not just a convenient scale around which to organize discussion but also a concept more seminal in its ‘putative relationality’ than often appreciated. The concept contains important seeds of subsequent and future research on city systems more generally or else prompts them to the extent that the scale of urbanization and functional urban relations may now exceed it. I suggest five themes within this agenda that speak to the underplayed and emergent (1) morphological, (2) informational, (3) incubatory, (4) relational properties of megalopolitan systems and how the latter property of city systems promises (5) a positionalist perspective that reaches beyond urban economic organization at the megalopolitan scale. I note in conclusion the possible additional benefits of this agenda in promoting a measure of intra- and inter-disciplinary dialogue on a subject otherwise characterized by fragmentation.
One-Pot Process in Scalable Bath for Water-Dispersed ZnS Nanocrystals with the Tailored Size
Jung, Hyunsung,Phelps, Tommy J.,Rondinone, Adam J.,Jellison, Gerald E.,Duty, Chad E.,Han, Kee Sung,Moon, Ji-Won American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.5
<P>Well-dispersed ZnS nanocrystals with tailored size in aqueous solutions were synthesized by employing cysteine-sulfur (Cys-S) complexes with low molecular weight in a scalable anoxic vessel. High yield production of water-dispersed ZnS nanocrystals on a 10-L scale was demonstrated in an aqueous solution process. The average crystallite size of ZnS was controlled by changing the ratio of the cysteine to sulfide in the applied Cys-S complexes. A decrease in the crystallite size of ZnS likely resulted in both the blue shift of peak positions and the relative variation of peak intensities in the photoluminescence properties. Additionally, the pH-dependent stability against aggregation of ZnS nanocrystals was investigated to reduce agglomeration.</P>
Extracellular Synthesis of Magnetite and Metal-Substituted Magnetite Nanoparticles
Roh, Y.,Vali, H.,Phelps, T. J.,Moon, J.-W. American Scientific Publishers 2006 Journal of Nanoscience and Nanotechnology Vol.6 No.11
<P>We have developed a novel microbial process that exploits the ability of Fe(III)-reducing microorganisms to produce copious amounts of extracellular magentites and metal-substituted magnetite nanoparticles. The Fe(III)-reducing bacteria (<I>Theroanaerobacter ethanolicus</I> and <I>Shewanella</I> sp.) have the ability to reduce Fe(III) and various metals in aqueous media and form various sized magnetite and metal-substituted magnetite nano-crystals. The Fe(III)-reducing bacteria formed metal-substituted magnetites using iron oxide plus metals (e.g., Co, Cr, Mn, Ni) under conditions of relatively low temperature (<70 °C), ambient pressure, and pH values near neutral to slightly basic (pH = 6.5 to 9). Precise biological control over activation and regulation of the biosolid-state processes can produce magnetite particles of well-defined size (typically tens of nanometers) and crystallographic morphology, containing selected dopant metals into the magnetite (Fe3−<I>y</I>X<I>y</I>O4) structure (where X = Co, Cr, Mn, Ni). Magnetite yields of up to 20 g/L per day have been observed in 20-L vessels. Water-based ferrofluids were formed with the nanometer sized, magnetite, and metal-substituted biomagnetite particles.</P>
Gonzalez, John Michael,Phelps, Kelsey Jean Asian Australasian Association of Animal Productio 2018 Animal Bioscience Vol.31 No.7
Meat quality is a very difficult term to define because it means different things to different people. When purchasing beef, consumers in the United States are likely to consider color, price, marbling level, subcutaneous fat trim, or cut thickness when determining the quality of beef. Once consumers have consumed the product, meat quality becomes exponentially more difficult to define due to the subjective nature of this term. Traditionally, tenderness, juiciness, and flavor have been considered the three most important factors that determine the palatability of beef. Therefore, American meat science beef research and industry focus has turned to measuring and quantifying these 3 attributes objectively and subjectively, and to determining what influences them. In reviewing the scientific literature, attempting to meaningfully summarize the findings of the thousands of studies on beef meat quality is impossible due to the inherent differences in the objective and methodology of studies. Fortunately, the United States beef industry and their national trade association, the National Cattlemen's Beef Association (NCBA), have conducted numerous surveys and audits to characterize the quality of the products being produced and marketed by their cattlemen and the palatability perceptions of their consumers. The data produced by these studies is quite large and impossible to summarize in entirety in this review. Therefore, this review concentrates on the most important attributes that determine the value of a beef carcass and objectively measured and consumer-assessed palatability characteristics of fresh meat from these carcasses from 1987 through 2010.
Review: NanoFermentation을 이용한 자철석 합성연구
문지원,노열,Moon, Ji-Won,Roh, Yul,Phelps, Tommy J. 대한자원환경지질학회 2012 자원환경지질 Vol.45 No.2
미생물에 의한 광물합성은 지화학적 순환 및 미생물의 독성에 대한 저항기작을 위해 주로 연구되어져 왔으나 본 논문에서는 NanoFermentation을 통한 경제적, 친환경적, 저에너지, 대량생산이 가능한 나노입자 크기의 자철석 합성연구를 소개하고 또한 초상자성(Superparamagnetism)과 준강자성(Ferrimagnetism)을 결정짓는 입자크기에 대한 조절인자를 살펴보고자 한다. NanoFermentation을 통한 자철석의 합성 시 입자 크기의 조절 인자는 선택된 미생물 종 및 배양 온도, 배양액의 화학적 조성, 배양기간, 치환된 원소의 조성 및 함량, 자철석 전조물질(Precursor)의 형태, 반응 부피의 증가 및 자철석 전조물질의 농도와 같은 조건들의 조합에 의해 결정되어지며 주로 핵형성 및 결정 성장의 균형에 의해 조절된다. 생광물화 작용을 통한 무기재료의 합성 연구는 앞서 언급한 지표에서의 원소의 순환 및 미생물 생리학적 측면뿐만 아니라 최종 산물인 나노입자의 대량 생산을 통해 재료학적 응용 분야에도 많은 파급 효과가 예상된다. Biomineralization has been explored for geochemical cycles and microbial tolerance mechanisms to metal toxicity. Here, we are introducing NanoFermentation which enables economic, environmentally friendly, requiring low input energy, and scalable manufacturing of nano-dimensioned magnetite. We are also focusing on controlling factors of crystallite size which can determine superparamagnetism and ferrimagnetism. Controlling factors are such as microbial species, temperature, incubation time, medium composition, substituted elements and their concentration, precursor type, reaction volume, precursor concentration density and their combinations. Crystallite size distribution of biomagnetite depends on the balance between nuclei generation and crystal growth. Biomineralization will elucidate elemental cycles on earth crust and microbial ecology as well as it will be applied to material sciences and devices via massive production of nanomaterials.