A Mononuclear Nonheme Iron(IV)-Amido Complex Relevant for the Compound II Chemistry of Cytochrome P450

Lu, Xiaoyan,Li, Xiao-Xi,Seo, Mi Sook,Lee, Yong-Min,Clé,mancey, Martin,Maldivi, Pascale,Latour, Jean-Marc,Sarangi, Ritimukta,Fukuzumi, Shunichi,Nam, Wonwoo American Chemical Society 2019 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.141 No.1

<P>A mononuclear nonheme iron(IV)-amido complex bearing a tetraamido macrocyclic ligand, [(TAML)Fe<SUP>IV</SUP>(NHTs)]<SUP>−</SUP> (<B>1</B>), was synthesized via a hydrogen atom (H atom) abstraction reaction of an iron(V)-imido complex, [(TAML)Fe<SUP>V</SUP>(NTs)]<SUP>−</SUP> (<B>2</B>), and fully characterized using various spectroscopies. We then investigated (1) the p<I>K</I><SUB>a</SUB> of <B>1</B>, (2) the reaction of <B>1</B> with a carbon-centered radical, and (3) the H atom abstraction reaction of <B>1</B>. To the best of our knowledge, the present study reports for the first time the synthesis and chemical properties/reactions of a high-valent iron(IV)-amido complex.</P> [FIG OMISSION]</BR>

Alfalfa Regrowth Potential and Root Carbohydrates in Response to Fall Dormancy

Xiaoyan Lu,Shuren Ji,Chen Hou,Zhizhuo Geng,Yixin Shen 한국초지조사료학회 2016 한국초지조사료학회 학술대회논문집 Vol.2016 No.08

Cone-beam computed tomographic evaluation of mandibular incisor alveolar bone changes for the intrusion arch technique: A retrospective cohort research

Lu Lin,Si Jiaping,Wang Zhikang,Chen Xiaoyan 대한치과교정학회 2024 대한치과교정학회지 Vol.54 No.2

Objective: Alveolar bone loss is a common adverse effect of intrusion treatment. Mandibular incisors are prone to dehiscence and fenestrations as they suffer from thinner alveolar bone thickness. Methods: Thirty skeletal class II patients treated with mandibular intrusion arch therapy were included in this study. Lateral cephalograms and cone-beam computed tomography images were taken before treatment (T1) and immediately after intrusion arch removal (T2) to evaluate the tooth displacement and the alveolar bone changes. Pearson’s and Spearman’s correlation was used to identify risk factors of alveolar bone loss during the intrusion treatment. Results: Deep overbite was successfully corrected (P < 0.05), accompanied by mandibular incisor proclination (P < 0.05). There were no statistically significant change in the true incisor intrusion (P > 0.05). The labial and lingual vertical alveolar bone levels showed a significant decrease (P < 0.05). The alveolar bone is thinning in the labial crestal area and lingual apical area (P < 0.05); accompanied by thickening in the labial apical area (P < 0.05). Proclined incisors, non-extraction treatment, and increased A point-nasion-B point (ANB) degree were positively correlated with alveolar bone loss. Conclusions: While the mandibular intrusion arch effectively corrected the deep overbite, it did cause some unwanted incisor labial tipping/flaring. During the intrusion treatment, the alveolar bone underwent corresponding changes, which was thinning in the labial crestal area and thickening in the labial apical area vice versa. And increased axis change of incisors, non-extraction treatment, and increased ANB were identified as risk factors for alveolar bone loss in patients with mandibular intrusion therapy.

DnaJ of Streptococcus suis Type 2 Contributes to Cell Adhesion and Thermotolerance

Zhang, Xiaoyan,Jiang, Xiaowu,Yang, Ling,Fang, Lihua,Shen, Hongxia,Lu, Xingmeng,Fang, Weihuan The Korean Society for Microbiology and Biotechnol 2015 Journal of microbiology and biotechnology Vol.25 No.6

To examine if the molecular chaperone DnaK operon proteins of Streptococcus suis type 2 (SS2) are involved in adhesion to host cells, the abundance values of these proteins from the surface of two SS2 strains of different adhesion capability were compared. Their roles in growth and adhesion to human laryngeal epithelial cell line HEp-2 cells were investigated on SS2 strain HA9801 and its mutants with DnaK operon genes partially knocked-out (PKO mutant) under heat stress. The major difference was that DnaJ was more abundant in strain HA9801 than in strain JX0811. Pretreatment of the bacteria with hyperimmune sera to DnaJ, but not with those to other proteins, could significantly reduce SS2 adhesion to HEp-2 cells. PKO of dnaJ g ene resulted in decreased SS2 growth at 37℃ and 42℃, and reduced its adhesion to HEp-2 cells. The wild-type strain stressed at 42℃ had increased expression of DnaJ on its surface and elevated adhesion to HEp-2 cells, which was also inhibitable by DnaJ specific antiserum. These results indicate that the DnaJ of S. suis type 2 is important not only for thermotolerance but also for adhesion to host cells. Because DnaJ expression is increased upon temperature upshift with increased exposure on the bacterial surface, the febrile conditions of the cases with systemic infections might help facilitate bacterial adhesion to host cells. DnaJ could be one of the potential candidates as a subunit vaccine because of its good immunogenicity.

Towards a Framework for Assuring Cyber Physical System Security

Tianbo Lu,Jinyang Zhao,Lingling Zhao,Yang Li,Xiaoyan Zhang 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.3

Today, cyber physical systems (CPS) are becoming popular in power networks, healthcare devices, transportation networks, industrial process and infrastructures. As cyber physical systems are used more and more extensively and thoroughly, security of cyber physical systems has become the utmost important concern in system design, implementation and research. Many kinds of attacks arise (e.g. the Stuxnet worm), causing heavy losses and serious potential security risks. For the past few years, researchers are focusing their researches on different aspects of security of cyber physical systems. In this paper, we propose a security framework assuring the security of cyber physical systems and analyze main universities and institutes studying CPS security and their relations in three levels: CPS security objectives, CPS security approaches and security in specific CPS applications. Finally, a conclusion of this article is given.

A Framework for Analyzing Anonymous Network Topology

Tianbo Lu,Shixian Du,Yang Li,Peiyuan Dong,Xiaoyan Zhang 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.4

Nowadays, Internet privacy becomes more and more important and sensitive, and has been one of the latest buzz words to hit the Internet world. In response to protect the privacy of Internet users, a variety of privacy enhancing technologies (PETs) have emerged. As one of privacy enhancing technologies, anonymous communication has been extensively studied from various aspects by researchers. Node churn is frequent in anonymous network, which make it difficult to maintain a stable network topology, therefore it is necessary to get more insight into the overall anonymous network topology. In this work, in order to better grasp the present situation of research, we investigate existing organizations and universities which study anonymous communication from the perspective of network topology, and related projects. Then we survey related papers to anonymous communication published in recent years, which focus on the analysis of node selection (especially in the Tor). In addition, we present a framework of anonymous communication network topology, and a visual illustration of this analysis that shows the progression of the research of network topology and node discovery in anonymous communication. Finally, some related problems and follow-up study are presented to be studied deeply in future.

NSDA : A Novel Node Selecting Optimal Algorithm Based on Dijkstra

Tianbo Lu,Jiao Zhang,Lingling Zhao,Yang Li,Xiaoyan Zhang 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.6

This paper first represent the basic conceptions of anonymous communication, then introduce the fundamentals in Anonymous Communication. Afterwards, we went deep to the classification of anonymous network topological, therefore we could get a better understanding on P2P anonymous communication system. We also systematically analyzes the existing node-select algorithms. Furthermore, we propose and implement a new node selection algorithm based on Dijkstra algorithm, named NSDA algorithm. We give a belief description about the backgrounds and design of NSDA Algorithm. The algorithm can combine the node properties with link properties to select node, which can adjust the system performancing and anonymity. In order to evaluate the NSDA algorithm, we have done experiments in Network Simulator 3, and we also explain the reason why we choose Network Simulator 3 as the simulate tool. In the end, we analyze the characteristics of NSDA algorithm according to the results of experiments.

Code Analysis and Improvement of Onion Routing Anonymous Systems

Tianbo Lu,Youwen Wang,Lingling Zhao,Yang Lin,Xiaoyan Zhang 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.8

With the development of Internet technology, network based activities such as e-commerce, internet voting and e-government, etc. have become increasingly frequent, People are increasingly concerned about the identity of network activity, content and other private information. In order to protect user privacy in network communications, governments, companies, universities and research institutes are pushing the research and development of the onion routing systems (TOR). Tor is the most popular anonymous communication system currently, which is based on technology of the second-generation onion routing. Tor has a low latency, encrypted data transmission, secure channel, etc., which are widely used in anonymous Web browsing, instant messaging, Secure Shell Client (SSH), etc. However, the development of the onion routing systems is constrained by complicated code factors. According to this situation, this paper put forward an overall architecture of TOR code, which contains Application Needs, Code Analysis and Improvement. This paper summarizes the overall framework of tor code structure, in order to make the code structure clearer, the whole code module is divided into several sub modules, using the function call diagram and UML diagram illustrates the main function of each module and call relation between each module. This paper gives code analysis for anonymous architecture of TOR. Finally, this paper put forward the improvement of routing algorithms of TOR. Based on this paper, a method has been created which is used to understand the tor code easily. Furthermore, systematic analysis of the tor code provided in this paper aims to research the working principle and promote the further development of the onion routing.

Achieving One-Electron Oxidation of a Mononuclear Nonheme Iron(V)-Imido Complex

Hong, Seungwoo,Lu, Xiaoyan,Lee, Yong-Min,Seo, Mi Sook,Ohta, Takehiro,Ogura, Takashi,Clé,mancey, Martin,Maldivi, Pascale,Latour, Jean-Marc,Sarangi, Ritimukta,Nam, Wonwoo American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.41

<P>A mononuclear nonheme iron(V)-imido complex bearing a tetraamido macrocyclic ligand (TAML), [Fe<SUP>V</SUP>(NTs)(TAML)]<SUP>−</SUP> (<B>1</B>), was oxidized by one-electron oxidants, affording formation of an iron(V)-imido TAML cation radical species, [Fe<SUP>V</SUP>(NTs)(TAML<SUP>+•</SUP>)] (<B>2</B>); <B>2</B> is a diamagnetic (<I>S</I> = 0) complex, resulting from the antiferromagnetic coupling of the low-spin iron(V) ion (<I>S</I> = 1/2) with the one-electron oxidized ligand (TAML<SUP>+•</SUP>). <B>2</B> is a competent oxidant in C–H bond functionalization and nitrene transfer reaction, showing that the reactivity of <B>2</B> is greater than that of <B>1</B>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2017/jacsat.2017.139.issue-41/jacs.7b08161/production/images/medium/ja-2017-081612_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja7b08161'>ACS Electronic Supporting Info</A></P>

Catabolite Control Protein A of Streptococcus suis Type 2 Contributes to Sugar Metabolism and Virulence

Yulong Tang,Wei Wu,Xiaoyan Zhang,Zhongyan Lu,Jianshun Chen,Weihuan Fang 한국미생물학회 2012 The journal of microbiology Vol.50 No.6

Catabolite control protein A (CcpA) is the major transcriptional regulator in carbon catabolite repression in several Gram-positive bacteria. We attempted to characterize the role of a CcpA homologue of Streptococcus suis type 2 in sugar metabolism and virulence. Addition of glucose or sucrose to the defined medium significantly reduced the activity of raffinose-inducible α-galactosidase, cellobiose-inducible β-glucosidase, and maltose-inducible α-glucosidase of the wildtype strain by about 9, 4, and 2-3 fold, respectively. Deletion of ccpA substantially derepressed the effects of repressing sugars on α-galactosidase or β-glucosidase activity. The ccpA deletion mutant showed reduced expression of virulence genes sly and eno (P<0.05), decreased adhesion to and invasion into endothelial cells (P<0.05), and attenuated virulence to mice with significant reduction of death rate and bacterial burden in organs, as compared to the wild-type strain. Both the in vitro and in vivo defect phenotypes were reversible by ccpA complementation. Thus, this study shows that CcpA of S. suis type 2 plays an important role in carbon catabolite repression and virulence.