닫혀진 보제 끈 이론의 새로운 양자화

한승기, Wu Ke, Zhang Yuan-Zhong 忠北大學校部設基礎科學硏究所 1987 自然科學硏究 Vol.1 No.1

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고지방 식이를 섭취한 흰쥐에서 마테의(Ilex praguariensis) 중성지방과 콜레스테롤 저하 효과

박지연,안희정,정주현,변정은,이해진,장원원,위해리,최세림,안진표,이명숙 誠信女子大學校 生活文化硏究所 2012 生活文化硏究 Vol.26 No.2

With obesity caused by high fat intake having various adverse effects on people of today's society, the aim of this study is to examine the lowering effect of proportional mate intake on tissue triglyceride and cholesterol levels. Mate, binomial name Ilex paraguariensis, is a species of holly (family Aquifoliaceae), well-known as the source of the mate beverage, which is native to subtropical South America. Five-week-old male Sprague-Dawleys weighing about 200g were used for this experiment. These rats were fed on a diet mixed with 60% fat and instant Mate powder in market circulation. They were divided into four groups, with the control group on a normal diet (n=6), a group on a high fat diet (HFD) (n=6), a group on a high fat diet containing 2% mate powder (MT2) (n=6), and the last group on a high fat diet containing 4% mate powder (MT4) (n=6). The food efficiency ratio made no difference in the MT2 group compared to the HFD group. With the intake of mate powder, serum and tissue triglycerides were decreased in the MT2 group. Especially notable was the fall of triglyceride levels in the liver in the MT2 group by roughly 60%, compared to those of the HFD group. Cholesterol levels in epididymal fat pads were sig-nificantly decreased - by 60% - in the MT4 group compared to those of the HFD group. Also, as a result of DPPH(1,1-Diphenyl-2-picrylhydrazyl) assay, the anti-oxidant activity of Mate powder showed a similar level to that of vitamin E. These findings indicate that triglyceride and cholesterol levels in liver and epididymal fat pads are decreased by the intake of Mate powder. That the dose of Mate powder in the MT4 group had a signifiant effect means that Mate may be capable of interfering in triglyceride and cholesterol levels.

A New Theory for Acupuncture: Promoting Robust Regulation

Yuan Xu,Yang Guo,Yuru Song,Kuo Zhang,Yiping Zhang,Qiang Li,Shouhai Hong,Yangyang Liu,Yi Guo 사단법인약침학회 2018 Journal of Acupuncture & Meridian Studies Vol.11 No.1

Robustness, an ability of biological networks to uphold their functionalities in the face of perturbations, is a key characteristic of all living systems. Acupuncture is a procedure in which fine needles are inserted into an individual at discrete points and then manipulated, with the intent of preventing and curing diseases. Acupuncture does not directly eliminate pathogenic factors or pathological tissue; rather, acupuncture enhances the ability of the human body to self-medicate itself by activating complex regulatory systems and by maintaining physiological homeostasis to prevent or treat diseases. From this point of view, the effect of acupuncture on the human body is more likely a kind of regulation to promote robustness. That is to say, acupuncture has the ability to promote robustness. In this article, we review the properties and functions of acupuncture in preventing and treating diseases and in maintaining health by enhancing robustness.

A Numerical Study on Cavitation Suppression Using Local Cooling

Zhang, Yuan-Yuan,Sun, Xiao-Jing,Huang, Dian-Gui Korean Society for Fluid machinery 2010 International journal of fluid machinery and syste Vol.3 No.4

This study strives to develop an effective strategy to inhibit cavitation inception on hydrofoils by using local cooling technique. By setting up a temperature boundary condition and cooling a small area on the upper surface of a hydrofoil, the fluid temperature around the cooling surface will be decreased and thereby the corresponding liquid saturation pressure will drop below the lowest absolute pressure within the flow field. Hence, cavitation can never occur. In this paper, a NACA0015 hydrofoil at $4^{\circ}$ angle of attack was numerically investigated to verify the effectiveness of the proposed technique. The CFD results indicate that the cooling temperature and the cooling surface roughness are the critical factors affecting the success of such technique used for cavitation suppression.

Controlled synthesis of Co₂C nanochains using cobalt laurate as precursor: Structure, growth mechanism and magnetic properties

Zhang, Yajing,Zhu, Yuan,Wang, Kangjun,Li, Da,Wang, Dongping,Ding, Fu,Meng, Dan,Wang, Xiaolei,Choi, Chuljin,Zhang, Zhidong Elsevier 2018 Journal of magnetism and magnetic materials Vol.456 No.-

<P><B>Abstract</B></P> <P>Cobalt carbides (Co<SUB>2</SUB>C and Co<SUB>3</SUB>C) nanocomposites exhibit interesting hard magnetic property, controlled synthesis of individual phase facilitates to clarify the magnetism of each, but it is difficult to obtain the single phase. We present a new approach to address this issue via a polyol refluxing process, using cobalt laurate as the precursor. The single phase Co<SUB>2</SUB>C magnetic nanochains self-assembled by nanoparticles are synthesized. The precursor is the key factor for controlling the growth kinetics of the Co<SUB>2</SUB>C nanochains. Cobalt, instead of cobalt carbides, is produced if cobalt chloride, acetate and acetylacetonate replace cobalt laurate as the precursor, respectively. The evolution of the growth process has been studied. In the formation of Co<SUB>2</SUB>C, first fcc-Co produces, then it transforms into Co<SUB>2</SUB>C by carbon diffusion process, and the produced carbon first exists in disordered state and then a small amount of them transforms into graphite. Saturation magnetization (<I>Ms</I>) of Co<SUB>2</SUB>C nanochains obtained at 300 °C for 20, 60, and 180 min are 27.1, 18.9, and 10.9 emu g<SUP>−1</SUP>, respectively. The decrease of <I>Ms</I> caused by increasing carbon content, and the carbon content are much larger than the stoichiometric ratio value of Co<SUB>2</SUB>C (9.2 wt%). The Co<SUB>2</SUB>C nanochains have mesoporous pore of 3.8 nm and the specific surface area of 48.6 m<SUP>2</SUP> g<SUP>−1</SUP>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Co<SUB>2</SUB>C magnetic nanochains are synthesized using cobalt laurate as the precursor in TEG. </LI> <LI> The precursor of cobalt laurate is the key factor for controlling the growth kinetics of Co<SUB>2</SUB>C nanochains. </LI> <LI> Ms of Co<SUB>2</SUB>C nanochains obtained at 300 °C for 20, 60, and 180 min are 27.1, 18.9, and 10.9 emu g<SUP>−1</SUP>, respectively. </LI> <LI> The decrease of Ms is caused by increasing carbon content with increasing reaction time. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>We present a new approach to obtain single phase Co<SUB>2</SUB>C nanochains by using cobalt laurate as the precursor.</P> <P>[DISPLAY OMISSION]</P>

A Range-Based Localization Algorithm for Wireless Sensor Networks

Zhang Yuan,Wu Wenwu,Chen Yuehui The Korea Institute of Information and Commucation 2005 Journal of communications and networks Vol.7 No.4

Sensor localization has become an essential requirement for realistic applications over wireless sensor networks (WSN). In this paper we propose an ad hoc localization algorithm that is infrastructure-free, anchor-free, and computationally efficient with reduced communication. A novel combination of distance and direction estimation technique is introduced to detect and estimate ranges between neighbors. Using this information we construct unidirectional coordinate systems to avoid the reflection ambiguity. We then compute node positions using a transformation matrix [T], which reduces the computational complexity of the localization algorithm while computing positions relative to the fixed coordinate system. Simulation results have shown that at a node degree of 9 we get $90\%$ localization with $20\%$ average localization error without using any error refining schemes.

MiRNA320a Inhibitor-Loaded PLGA-PLL-PEG Nanoparticles Contribute to Bone Regeneration in Trauma-Induced Osteonecrosis Model of the Femoral Head

Zhang Ying,Li Chuan,Wei Qiushi,Yuan Qiang,He Wei,Zhang Ning,Dong Yiping,Jing Zhenhao,Zhang Leilei,Wang Haibin,Cao Xiangyang 한국조직공학과 재생의학회 2024 조직공학과 재생의학 Vol.21 No.1

BACKGROUND: This study aimed to explore the effect of a nanomaterial-based miR-320a inhibitor sustained release system in trauma-induced osteonecrosis of the femoral head (TIONFH). METHODS: The miR-320a inhibitor-loaded polyethylene glycol (PEG)- Poly(lactic-co-glycolic acid) (PLGA)- Poly-L-lysine (PLL) nanoparticles were constructed using the double emulsion method. The TIONFH rabbit model was established to observe the effects of miR-320a inhibitor nanoparticles in vivo. Hematoxylin–eosin staining and microcomputed tomography scanning were used for bone morphology analysis. Bone marrow mesenchymal stem cells (BMSCs), derived from TIONFH rabbits, were used for in vitro experiments. Cell viability was determined using the MTT assay. RESULTS: High expression of miR-320a inhibited the osteogenic differentiation capacity of BMSCs in vitro by inhibiting the expression of the osteoblastic differentiation markers ALP and RUNX2. MiR-320a inhibitor-loaded PEG-PLGA-PLL nanoparticles were constructed with a mean loading efficiency of 1.414 ± 0.160%, and a mean encapsulation efficiency of 93.45 ± 1.24%, which released 50% of the loaded miR-320a inhibitor at day 12 and 80% on day 18. Then, inhibitor release entered the plateau. After treatment with the miR-320a inhibitor nanoparticle, the empty lacunae were decreased in the femoral head tissue of TIONFH rabbits, and the osteoblast surface/bone surface (Ob.S/BS), osteoblast number/bone perimeter (Ob.N/B.Pm), bone volume fraction, and bone mineral density increased. Additionally, the expression of osteogenic markers RUNX2 and ALP was significantly elevated in the TIONFH rabbit model. CONCLUSION: The miR-320a inhibitor-loaded PEG-PLGA-PLL nanoparticle sustained drug release system significantly contributed to bone regeneration in the TIONFH rabbit model, which might be a promising strategy for the treatment of TIONFH. BACKGROUND: This study aimed to explore the effect of a nanomaterial-based miR-320a inhibitor sustained release system in trauma-induced osteonecrosis of the femoral head (TIONFH). METHODS: The miR-320a inhibitor-loaded polyethylene glycol (PEG)- Poly(lactic-co-glycolic acid) (PLGA)- Poly-L-lysine (PLL) nanoparticles were constructed using the double emulsion method. The TIONFH rabbit model was established to observe the effects of miR-320a inhibitor nanoparticles in vivo. Hematoxylin–eosin staining and microcomputed tomography scanning were used for bone morphology analysis. Bone marrow mesenchymal stem cells (BMSCs), derived from TIONFH rabbits, were used for in vitro experiments. Cell viability was determined using the MTT assay. RESULTS: High expression of miR-320a inhibited the osteogenic differentiation capacity of BMSCs in vitro by inhibiting the expression of the osteoblastic differentiation markers ALP and RUNX2. MiR-320a inhibitor-loaded PEG-PLGA-PLL nanoparticles were constructed with a mean loading efficiency of 1.414 ± 0.160%, and a mean encapsulation efficiency of 93.45 ± 1.24%, which released 50% of the loaded miR-320a inhibitor at day 12 and 80% on day 18. Then, inhibitor release entered the plateau. After treatment with the miR-320a inhibitor nanoparticle, the empty lacunae were decreased in the femoral head tissue of TIONFH rabbits, and the osteoblast surface/bone surface (Ob.S/BS), osteoblast number/bone perimeter (Ob.N/B.Pm), bone volume fraction, and bone mineral density increased. Additionally, the expression of osteogenic markers RUNX2 and ALP was significantly elevated in the TIONFH rabbit model. CONCLUSION: The miR-320a inhibitor-loaded PEG-PLGA-PLL nanoparticle sustained drug release system significantly contributed to bone regeneration in the TIONFH rabbit model, which might be a promising strategy for the treatment of TIONFH.

Generation of Landing Footprints for Re-entry Vehicles Based on Lateral Profile Priority

Yuan-long Zhang,Yu Xie,Xin Xu 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.1

This study proposes a method for calculating the landing footprints of re-entry vehicles based on the three-dimensional acceleration profile. Unlike the traditional case in which the reference angle-of-attack profile is given in advance, here, the manoeuvrability of the vehicle is enhanced owing to the release of the constraints of the angle-of-attack profile. Compared with the traditional methods of generating landing footprints, this method is more challenging because it is necessary to adjust the angle-of-attack and the bank angle simultaneously to obtain all feasible trajectories. With the enhancement of manoeuvrability, the traditional landing footprints solving strategy with a fixed bank direction under the premise of a given angle-of-attack is expected to make the footprints of the result locally smaller. Therefore, a layered design based on a three-dimensional profile and lateral priority strategy is proposed to solve the problem. First, a lateral flight corridor considering various path constraints is constructed. Then, the boundary interpolation of the flight corridor is used to generate an initial lateral profile. The longitudinal profile corresponding to the lateral profile is analysed according to the coupling relationship between the longitudinal and lateral profiles, and the corresponding trajectory is then obtained by numerical integration. The tentative landing footprints can be obtained by traversing all feasible profiles in the lateral corridor. Finally, to solve the problem of inaccuracy in the solution of landing footprints, the core innovation of this study is the generation of multiple groups of different lateral flight corridors by adjusting the initial and terminal bank directions. By solving the tentative landing footprints under different flight corridors and merging them, highly accurate landing footprints were obtained. The proposed method is tested with the CAV-H model of Lockheed Martin, and the results are compared with those of traditional methods to verify its effectiveness and feasibility.

Effects of Insect Hormones on the Replication of Nucleopolyhedrovirus

Zhang, Zhi-Fang,Yi, Yong-Zhu,Xiao, Qing-Li,He, Jia-Lu,Zhou, Ya-Jing,Zhang, Yuan-Xing Korean Society of Sericultural Science 2002 International Journal of Industrial Entomology Vol.4 No.2

An experimental study was undertaken to quantify the effects of insect hormones on the replication of nucleopolyhedrovirus (NPV). The results demonstrated that TCID/ sub 50/ at 72 h post-infection (hpi) rose systematically from 0.55$\times$10$^{8}$ /m1, for untreated cells, up to 1.67$\times$10$^{8}$ / ml at 3$\mu$g/ml, then dropped down to 1.45$\times$10$^{8}$ /m1 at 4 $\mu$g/ml, by adding ecdysone to the culture medium for Bm-N cells infected with a wild-type Bambyx mori. nucleopolyhedrovirus (BmNPV). The optimum enhancement of about 3 times on budded virus (BV) titer at 72 hpi was given at 3 $\mu$g/ml of ecdysone. While the polyhedra number had no obvious variation within the range of concentrations from 0 to 4 $\mu$g/ml. By addition of juvenile hormone analogue (JHA) into the media with this concentration range, the BmNPV TCID/ sub 50/ and polyhedra number at 72 hpi did not show significant changes. Also, the addition of either 3 $\mu$g/ml of ecdysone or 3 $\mu$g/ml of JHA to the culture media did not appear to affect the TCID/ sub 50/ and polyhedra number significantly in infected Sf-21 cells with the autographa californica nucleopolyhedrovirus (AcMNPV).

Effect of Copper Substrate Surface Orientation on the Reductive Functionalization of Graphene

Zhang, Xu,Luo, Da,Zhang, Hanyang,Hwang, Dae Yeon,Park, Sung O.,Li, Bao-Wen,Biswal, Mandakini,Jiang, Yi,Huang, Yuan,Kwak, Sang Kyu,Bielawski, Christopher W.,Ruoff, Rodney S. American Chemical Society 2019 Chemistry of materials Vol.31 No.21

<P>Although substrate composition can influence the chemical reactivity of graphene, substrate lattice orientation provides a valuable alternative. The effect of Cu surface orientation on the reactivity of graphene was explored through a reductive transformation. Among the substrates tested, only Cu(111) led to the efficient, fast and uniform functionalization of graphene, as demonstrated by Raman mapping, and this arose from compressive strain induced by Cu(111). Functionalization effectively relaxes the strain, which can be subsequently reintroduced after thermal treatment. Theoretical calculations showed how compression facilitates the reduction and hybridization of carbon atoms, while coupling experiments revealed how kinetics may be used to control the reaction. The number of graphene layers and their stacking modes were also found to be important factors. In a broader context, a description of how graphene undergoes chemical modification when positioned on certain metal substrates is provided.</P> [FIG OMISSION]</BR>