Production of D-Lactate Utilizing Multiple Sugars Derived from Biomass by Engineered E. coli

Department of Biomedical EngineeringCo-utilizing of multiple carbon sources have been interested for decades in the synthetic biology field. To suppress the greenhouse effect, people have tried to find renewable energy sources. Biomass is the representative alternative carbon source, but pre-treatment and reprocessing steps of biomass are necessary to convert cellulose, and hemicellulose to sugars. Cellulose of biomass can be converted to glucose, and hemicellulose of biomass can be converted to xylose and arabinose. Constructing strain which can co-utilize multiple sugars is not only reducing pre-treatment cost but also increasing productivity of bio-chemical. We constructed two type of strains. One is strain which can co-utilize glucose, xylose and cellobiose by transformation of cellobiose pathway from Enterobacter Cloacae, and the other is strain which can co-utilize glucose, xylose and arabinose by genome engineering on araB promoter region. In this study, the research was conducted to confirm the ability to co-utilize multiple sugars and to produce lactic acid.ope

Cooperative Exchange with Substitutable Ties and Its Competitive Outcomes

With a model of tie substitution, a construct that reflects each actors evaluation of his or her social relations or networks, this study proposes that each actors subjective evaluation of objective structural constraints may facilitate or delay the realization of structural constraints in general and the division of cooperative benefits in particular. It shows the following: first, ego with few (perceived) substitutable ties is likely to accept the unequal allocation of cooperative benefits; second, symmetry in tiesubstitution at the global network suppresses (aggravates) competition for the division of cooperative outcomes when individual tie-substitution is low (high).This study was supported by the Institute of Management Research at Seoul National University

Organizational Knowledge and Localized Competition: A Case of a High Performer that is Socially Constructed

This study seeks to elucidate conditions under which high performers emerge independent of their internal resources even when competition in the output market is intense. In particular, I present an extended model of localized competition in which ill-informed producers compete with each other by observing the actions of their rivals and inferring the association between the cost and benefit of their action from observable market response to the action of their rivals. To this end, I combine three independent streams of research, including the ecological model of localized competition, organizational knowledge and Harrison Whites model of market (Carroll and Hannan 2000; Garicano 2000; Grant 1996; Nelson and Winter 1982; White 1981). An analytical strategy chosen is to parameterize the interplay of organizational knowledge and localized competition so that this study seeks to theorize a general competitive process that underlies the emergence of high performers without ignoring the role of firm heterogeneity in internal resources. In particular, this study characterizes market competition with respect to four parameters, including (1) the size of the neighborhood of a firm, (2) the upper and (3) lower bound of knowledge bases, and (4) a type of the market. The implications of this model are further explored in the context of multimarket competition as well as resource-partitioning.This study was supported by the Institute of Management Research at Seoul National universit

Mesenchymal stem cell-derived magnetic extracellular nanovesicles for targeting and treatment of ischemic stroke

Exosomes and extracellular nanovesicles (NV) derived from mesenchymal stem cells (MSC) may be used for the treatment of ischemic stroke owing to their multifaceted therapeutic benefits that include the induction of angiogenesis, anti-apoptosis, and anti-inflammation. However, the most serious drawback of using exosomes and NV for ischemic stroke is the poor targeting on the ischemic lesion of brain after systemic administration, thereby yielding a poor therapeutic outcome. In this study, we show that magnetic NV (MNV) derived from iron oxide nanoparticles (IONP)-harboring MSC can drastically improve the ischemic-lesion targeting and the therapeutic outcome. Because IONP stimulated expressions of therapeutic growth factors in the MSC, MNV contained greater amounts of those therapeutic molecules compared to NV derived from naive MSC. Following the systemic injection of MNV into transient middle-cerebral-artery-occlusion (MCAO)-induced rats, the magnetic navigation increased the MNV localization to the ischemic lesion by 5.1 times. The MNV injection and subsequent magnetic navigation promoted the anti-inflammatory response, angiogenesis, and anti-apoptosis in the ischemic brain lesion, thereby yielding a considerably decreased infarction volume and improved motor function. Overall, the proposed MNV approach may overcome the major drawback of the conventional MSC-exosome therapy or NV therapy for the treatment of ischemic stroke.

Targeted delivery of iron oxide nanoparticle-loaded human embryonic stem cell-derived spherical neural masses for treating intracerebral hemorrhage

This study evaluated the potential of iron oxide nanoparticle-loaded human embryonic stem cell (ESC)-derived spherical neural masses (SNMs) to improve the transportation of stem cells to the brain, ameliorate brain damage from intracerebral hemorrhage (ICH), and recover the functional status after ICH under an external magnetic field of a magnet attached to a helmet. At 24 h after induction of ICH, rats were randomly separated into three experimental groups: ICH with injection of phosphate-buffered saline (PBS group), ICH with intravenous injection of magnetosome-like ferrimagnetic iron oxide nanocubes (FION)-labeled SNMs (SNMs* group), and ICH with intravenous injection of FION-labeled SNMs followed by three days of external magnetic field exposure for targeted delivery by a magnet-embedded helmet (SNMs*+Helmet group). On day 3 after ICH induction, an increased Prussian blue-stained area and decreased swelling volume were observed in the SNMs*+Helmet group compared with that of the other groups. A significantly decreased recruitment of macrophages and neutrophils and a downregulation of pro-inflammatory cytokines followed by improved neurological function three days after ICH were observed in the SNMs*+Helmet group. Hemispheric atrophy at six weeks after ICH was significantly decreased in the SNMs*+Helmet group compared with that of the PBS group. In conclusion, we have developed a targeted delivery system using FION tagged to stem cells and a magnet-embedded helmet. The targeted delivery of SNMs might have the potential for developing novel therapeutic strategies for ICH.

On Regretful Hierarchy

This study evaluates the implications of regretful choices at the group level and suggests that regretful choices in the market may underlie the formation of hierarchy, i.e., a collectivity, which may not mitigate the hazards of transactions but serve to absorb personal emotions, i.e., regrets associated with market transactions. In so doing, this study seeks to identify the role of personal emotion in the theory of the firm vis-à-vis calculative trust that is arguably granted to the impersonal firm. [ABSTRACT FROM AUTHOR] Copyright of Seoul Journal of Business is the property of Seoul National University, College of Business Administration and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)This study was supported by the Institute of Management Research at Seoul National University

조직문제의 표본 공간에서 발생하는 관행선택에 관하여: 국지적 탐색의 확장 모형

I propose a model of routine-based choice, where an organization selects its niche to serve and chooses its way to serve the chosen niche. On the basis of local search (Cyert & March, 1963) and absorptive capacity (Cohen & Levinthal, 1989, 1990), I first define the knowledge base of an organization by a random variable on the problem space, whose feature is compared with fitness in the landscape (Levinthal, 1997). I then examine the performance implications of the model along the extended dimensions of the problem space, i.e., lugged, incomplete, and friction landscapes, which lead to sequential choice. Finally, I discuss the intensity and direction of organizational choice as being driven by the concern for the tendency of sequential choice.조직 내에서 반복적으로 발생하는 작업과정을 관행이라고 정의할 때, 본 연구는 관행선택이라는 모형을 이용하여, 조직이 자신의 목표시장을 선별하고, 그곳에서 사업을 영위하는 방식을 선택하는 활동을 설명하고자 한다. 우선, Cyert & March(1963)의 국지적 탐색 모형과 Cohen & Levinthal(1989, 1990)의 흡수역량 모형을 활용하여, 본 연구는 특정 조직이 가지고 있는 지식기반을 조직이 일상적으로 접하는 의사결정 문제에 대한 확률변수로 정의하고, 이를 Levinthal(1997)의 적합도 지형의 차원에서 비교 설명하였다. 그 다음, 본 연구는 관행에 따른 의사결정이 복잡지형, 불완전지형, 마찰지형 등 세 가지의 적합도 지형에서 어떠한 조직성과를 낳는지 살펴보았다. 이를 통해복수개의 의사결정 과제를 해결하는 순서에 따라 조직성과가 달라 질 수 있음을 순차적선택 효과라는 개념으로 살펴보았다. 마지막으로, 본 연구는 순차적 선택 효과로 인하여 개별 조직이 의사결정 과정에 투여하는 노력의 양과 그 선택대안들이 달라질 수 있음을논하였다.본 연구에 대한 서울대학교 노사관계 연구소의 연구비 지원에 감사를 표합니

自我에 기초하지 않은 사물의 질서

This study presents a structuralist account of the living-world, which aims to replace the firmly and widely accepted concept of a modern self along two related yet distinct dimensions of men: cognition and valuation. First, it shows that with a model of a parallel distributed processing, retrieval interference occurs without invoking the well concerted cognitive process called the self. Second, it shows informational influence without invoking biases in decision-making. From a Brunswikian approach, it suggests that a network with the unequal distribution of power is likely to experience group polarization. The theoretical implications of these observations are further discussed.본 논문은, 경험세계에 대한 구조주의적 설명, 특히 근대적 자아라는 개념을 대체하는 설명체계를 인지와 평가라는 상이한 그러나 상호 연관된 인성의 차원을 중심으로 살펴보고자 한다. 첫째, 인지 과정을 실체주의적으로 해석하는 대신, 즉, 자아와 같은 개념을 사용하지 않고, 평행분산처리의 모형을 중심으로 회상간섭이라는 인지적 현상을 설명하고 있다. 둘째, 개개인의 특정 대상에 대한 평가가 타인이 가지고 있는 평가와 연동되는 현상을 단순히 개인 의사결정 상의 심리적 편향으로 설명하지 않고, 에곤 브론스윜의 확률적 지능 모형에 기초하여 설명하고 있다. 구체적으로, 구성원간의 사회적 관계의 불균등이 집단수준에서의 의견쏠림 현상의 원인임을 논증하고 있다. 이와 관련된 이론적 함의를 추가로 논하고 있다.저자는 서울대학교 노사관계 연구소의 본 연구를 위한 연구비 지원에 감사를 표합니다

The Hazards of Leapfrog: Search Routines for Alliance Partner and Evolution of Organizational Capabilities

This study presents an evolutionary model of capability development and examines the role of strategic alliance in the evolution of organiza-tional capabilities. In particular, this study begins with the observation that each alliance partners capability development co-evolves. This study contributes to the literature on capability development by showing the following: (1) a firms strategic alliance is fitness-enhancing when its partners learning is ineffective; (2) without making additional efforts (i.e., in-house development), a firm is able to employ strategic alliances and to balance between exploitation and exploration to the extent that its (potential) partners are not effective learners; and (3) a rm is unlikely to balance between exploitation and exploration to the extent that its (potential) partners are effective learners.This study was supported by the Institute of Management Research at Seoul National University

Social Structure and Alliance Formation in the Korean Telecommunications Industry

본 연구는 한국 통신산업에서의 기업간의 사회적 관계구조가 전략적 제휴대상업체의 선택에 미치는 영향에 대해 고찰하고 있다. 본 연구의 주요 설명변수인 기업간의 사회적 관계구조는 각 기업의 최고경영자들의 학연에 관한 자료, 기업들의 주거래은행에 대한 자료를 이용하여 측정하였고, 종속변수인 전략적 제휴여부는 1996년도에 통신산업에 진출하기 위해 한국의 기업들이 형성한 컨소시움에 대한 자료를 사용하여 측정하였다. 통계적 분석의 결과는 기업간의 사회적 관계구조가 전략적 제휴대상 기업의 선정에 매우 유의한 영향을 미친다는 것을 보여주고 있다. 이 결과에 근거하여 본 연구의 한계점과 미래의 연구방향에 대해 논의한다