BREAKUP MODELING OF A LIQUID JET IN CROSS FLOW

K.-S. IM,K.-C. LIN,M.-C. LAI,M. S. CHON 한국자동차공학회 2011 International journal of automotive technology Vol.12 No.4

We propose a novel breakup model to simulate the catastrophic breakup regime in a supersonic cross flow. A developed model has been extended from an existing Kelvin-Helmholtz/Rayleigh-Taylor (K-H/R-T) hybrid model. A new mass reduction rate equation, which has critical effects on overall spray structure, is successfully adopted, and the breakup length, which is an important parameter in existing model, is replaced by the breakup initiation time. Measured data from the supersonic wind tunnel with a dimension of 762×152×127 mm was employed to validate the newly developed breakup model. A nonaerated injector with an orifice diameter of 0.5 mm is used to inject water into a supersonic flow prescribed by the momentum flux ratio of the liquid jet to free stream air, q0. The conservation-element and solution-element (CE/SE) method, a novel numerical framework for the general conservation law, is applied to simulate the supersonic compressible flow. The spray penetration height and average droplet size along with a spray penetration axis are quantitatively compared with data. The shock train flow structures induced by the presence of a liquid jet are further discussed.

Density Functional Theory Study of Conformation-Dependent Properties of Neutral and Radical Cationic <small>l</small>-Tyrosine and <small>l</small>-Tryptophan

Baek, K. Y.,Fujimura, Y.,Hayashi, M.,Lin, S. H.,Kim, S. K. American Chemical Society 2011 The Journal of physical chemistry A Vol.115 No.34

<P>Conformation-dependent properties of <SMALL>l</SMALL>-tyrosine and <SMALL>l</SMALL>-tryptophan in neutral and radical cations were studied by using the density functional theory (DFT) with a new density functional M05-2X. The results are compared with those obtained by using the conventional DFT (B3LYP). Results obtained by both types of DFT were in qualitative accord, including the existence of two conformational subgroups and their subgroup-dependent adiabatic ionization energy and hydrogen bonding. On the other hand, quantitative differences were found between the two DFT methods as well: the M05-2X method successfully reproduced experimental adiabatic ionization energy, whereas the B3LYP functional consistently yielded significantly lower values by 0.2–0.3 eV. More importantly, natural bond orbital (NBO) analysis for cationic conformers showed that all conformers of <SMALL>l</SMALL>-tyrosine and <SMALL>L</SMALL>-tryptophan undergo charge localization upon ionization regardless of the presence of intramolecular hydrogen bonding, unlike the case of <SMALL>l</SMALL>-phenylalanine that was treated earlier by other studies. Different degrees of charge localization among all three aromatic amino acids are explained by employing a simple model in which the aromatic amino acid is assumed to consist of two submoieties of distinct cationic core: the backbone and aromatic side chain. The difference in adiabatic ionization energy between these two submoieties is found to govern the degree of charge localization.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2011/jpcafh.2011.115.issue-34/jp200826z/production/images/medium/jp-2011-00826z_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp200826z'>ACS Electronic Supporting Info</A></P>

Mechanistic insights into the interaction between energetic oxygen ions and nanosized ZnFe₂O₄: XAS-XMCD investigations

Singh, Jitendra Pal,Kaur, Baljeet,Sharma, Aditya,Kim, So Hee,Gautam, Sanjeev,Srivastava, Ramesh Chandra,Goyal, Navdeep,Lim, Weol Cheol,Lin, H.-J.,Chen, J. M.,Asokan, K.,Kanjilal, D.,Won, Sung Ok,Lee, The Royal Society of Chemistry 2018 Physical Chemistry Chemical Physics Vol.20 No.17

<P>The interactions of energetic ions with multi-cation compounds and their consequences in terms of changes in the local electronic structure, which may facilitate intriguing hybridization between O 2p and metal d orbitals and magnetic ordering, are the subject of debate and require a deep understanding of energy transfer processes and magnetic exchange mechanisms. In this study, nanocrystals of ZnFe2O4 were exposed to O<SUP>7+</SUP> ions with an energy of 100 MeV to understand, qualitatively and quantitatively, the metal-ligand field interactions, cation migration and magnetic exchange interactions by employing X-ray absorption fine structure measurements and X-ray magnetic circular dichroism to get deeper mechanistic insights. Nanosized zinc ferrite nanoparticles (NPs) with a size of ∼16 nm synthesized in the cubic spinel phase exhibited deterioration of the crystalline phase when 100 MeV O<SUP>7+</SUP> ions passed through them. However, the size of these NPs remained almost the same. The behaviour of crystal deterioration is associated with the confinement of heat in this interaction. The energy confined inside the nanoparticles promotes cation redistribution as well as the modification of the local electronic structure. Prior to this interaction, almost 42% of Zn<SUP>2+</SUP> ions occupied AO4 tetrahedra; however, this value increased to 63% after the interaction. An inverse effect was observed for metal ion occupancies in BO6 octahedra. The L-edge spectra of Fe and Zn reveal that the spin and valence states of the metal ions were not affected by this interaction. This effect is also supported by K-edge measurements for Fe and Zn. The t2g/eg intensity ratio in the O K-edge spectra decreased after this interaction, which is associated with detachment of Zn<SUP>2+</SUP> ions from the lattice. The extent of hybridization, as estimated from the ratio of the post-edge to the pre-edge region of the O K-edge spectra, decreased after this interaction. The metal-oxygen and metal-metal bond lengths were modified as a result of this interaction, as determined from extended X-ray absorption fine structure measurements. These measurements further support the observation of cation migration from AO4 tetrahedra to AO6 octahedra and <I>vice versa</I>. The Fe L-edge magnetic circular dichroism spectra indicate that Fe<SUP>3+</SUP> ions occupying sites in AO4 tetrahedra and BO6 octahedra exhibited antiferromagnetic-like ordering prior to this interaction. The NPs that interacted with energetic O ions displayed a different kind of magnetic ordering.</P>

An unconventional role for miRNA: let-7 activates Toll-like receptor 7 and causes neurodegeneration

Lehmann, Sabrina M,Kr체ger, Christina,Park, Boyoun,Derkow, Katja,Rosenberger, Karen,Baumgart, Jan,Trimbuch, Thorsten,Eom, Gina,Hinz, Michael,Kaul, David,Habbel, Piet,K채lin, Roland,Franzoni, Eleonora,Ry Nature Publishing Group, a division of Macmillan P 2012 NATURE NEUROSCIENCE Vol.15 No.6

Activation of innate immune receptors by host-derived factors exacerbates CNS damage, but the identity of these factors remains elusive. We uncovered an unconventional role for the microRNA let-7, a highly abundant regulator of gene expression in the CNS, in which extracellular let-7 activates the RNA-sensing Toll-like receptor (TLR) 7 and induces neurodegeneration through neuronal TLR7. Cerebrospinal fluid (CSF) from individuals with Alzheimer's disease contains increased amounts of let-7b, and extracellular introduction of let-7b into the CSF of wild-type mice by intrathecal injection resulted in neurodegeneration. Mice lacking TLR7 were resistant to this neurodegenerative effect, but this susceptibility to let-7 was restored in neurons transfected with TLR7 by intrauterine electroporation of Tlr7<SUP>??/??</SUP> fetuses. Our results suggest that microRNAs can function as signaling molecules and identify TLR7 as an essential element in a pathway that contributes to the spread of CNS damage.

Study on After Cavity Interaction in a 140-GHz Model TE0,3 Gyrotron Using 3-D CFDTD PIC Simulation

Lin, M.,Illy, S.,Avramidis, K. A.,Thumm, M.,Jelonnek, J. Institute of Electrical and Electronics Engineers 2018 IEEE transactions on plasma science Vol. No.

<P>The possibility of dynamic after cavity interaction (ACI) in a down-scaled gyrotron model has been studied using a 3-D conformal finite-difference time-domain particle-in-cell simulation. The purpose has been to benchmark this type of simulation against previous numerical results obtained by other methods and tools and to obtain additional physical insight on the effect of dynamic ACI. The benchmarking has been successful, as a good agreement with the older results has been achieved. Thus, the algorithms developed and validated can be used for studying the issue in a larger scale or more realistic model with affordable computational resources in the near future.</P>

Wear rate of vertically grown ZnO nanowires sliding against steel micro-sphere

Lin, L.Y.,Seo, J.M.,Jeong, M.C.,Koo, K.J.,Kim, D.E.,Myoung, J.M. Elsevier Sequoia 2007 Materials science & engineering. properties, micro Vol.460 No.-

In this work, ZnO nanowires were grown on Si(100) wafer and sapphire(001) substrates using metal-organic chemical vapor deposition (MOCVD). The morphology and crystal structure of ZnO nanowires were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The wear characteristics of ZnO nanowires were measured using an atomic force microscopy (AFM) apparatus. A steel micro-sphere (radius of 12μm) was attached to the end of the AFM cantilever and slid against the ZnO nanowires using low normal load. The wear rate of ZnO nanowires was quantified by comparing the geometrical shape of ZnO nanowires before and after the wear test. Also, the adhesive force between the sphere and the nanowires was measured before and after the wear test. The increase of adhesive force is due to the increase in contact surface after the wear test.

Nuclear Receptor-Induced Chromosomal Proximity and DNA Breaks Underlie Specific Translocations in Cancer

Lin, C.,Yang, L.,Tanasa, B.,Hutt, K.,Ju, B.g.,Ohgi, K.A.,Zhang, J.,Rose, D.W.,Fu, X.D.,Glass, C.K.,Rosenfeld, M.G. Cell Press ; MIT Press 2009 Cell Vol.139 No.6

Chromosomal translocations are a hallmark of leukemia/lymphoma and also appear in solid tumors, but the underlying mechanism remains elusive. By establishing a cellular model that mimics the relative frequency of authentic translocation events without proliferation selection, we report mechanisms of nuclear receptor-dependent tumor translocations. Intronic binding of liganded androgen receptor (AR) first juxtaposes translocation loci by triggering intra- and interchromosomal interactions. AR then promotes site-specific DNA double-stranded breaks (DSBs) at translocation loci by recruiting two types of enzymatic activities induced by genotoxic stress and liganded AR, including activation-induced cytidine deaminase and the LINE-1 repeat-encoded ORF2 endonuclease. These enzymes synergistically generate site-selective DSBs at juxtaposed translocation loci that are ligated by nonhomologous end joining pathway for specific translocations. Our data suggest that the confluence of two parallel pathways initiated by liganded nuclear receptor and genotoxic stress underlies nonrandom tumor translocations, which may function in many types of tumors and pathological processes.

Factors Affecting the Incidence of Angel Wing in White Roman Geese: Stocking Density and Genetic Selection

Lin, M.J.,Chang, S.C.,Lin, T.Y.,Cheng, Y.S.,Lee, Y.P.,Fan, Y.K. Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.6

The present study investigated stocking density and genetic lines, factors that may alter the severity and incidence of angel wing (AW), in White Roman geese. Geese (n = 384) from two genetically selected lines (normal- winged line, NL, and angel-winged line, AL, respectively) and one commercial line (CL) were raised in four pens. Following common commercial practice, low-stocking-density (LD), medium-stocking-density, and high-stocking-density treatments were respectively administered to 24, 32, and 40 geese per pen at 0 to 3 weeks ($1.92m^2/pen$) and 4 to 6 weeks ($13.2m^2/pen$) of age and to 24, 30, and 36 geese at 7 to 14 weeks ($20.0m^2/pen$) of age. The results revealed that stocking density mainly affected body weight gain in geese younger than 4 weeks, and that geese subjected to LD had a high body weight at 2 weeks of age. However, the effect of stocking density on the severity score of AW (SSAW) and incidence of AW (IAW) did not differ significantly among the treatments. Differences were observed among the genetic stocks; that is, SSAW and IAW were significantly higher in AL than in NL and CL. Genetic selection generally aggravates AW, complicating its elimination. To effectively reduce IAW, stocking density, a suspected causal factor, should be lower than that presently applied commercially.

VIBRATION CONTROL OF STRUCTURES WITH INTEGRATED SENSORS AND ACTUATORS

R. M. LIN,M. K. LIM,K. M. NYANG 한국소음진동공학회 1997 한국소음진동공학회 국제학술대회논문집 Vol.1997 No.1

Subconjunctival gene delivery of the transcription factor GA-binding protein delays corneal neovascularization in a mouse model

Yoon, K C,Bae, J A,Park, H J,Im, S K,Oh, H J,Lin, X H,Kim, M Y,Lee, J H,Lee, S E,Ahn, K Y,Kim, K K Macmillan Publishers Limited 2009 Gene therapy Vol.16 No.8

Corneal neovascularization can reduce visual acuity. GA-binding protein (GABP) is a transcription factor that regulates the expression of target genes including vascular endothelial growth factor (VEGF) and roundabout4 (Robo4), which participate in pathologic angiogenesis. We assessed whether intraocular injection of the GABP gene affects the growth of new corneal blood vessels in a mouse ocular neovascularization model. Transfection of human GABPα and GABPβ gene (GABPα/β) into human conjunctival epithelial cells resulted in decreased VEGF and Robo4 expression. Three groups of mice underwent chemical and mechanical denudation of the corneal epithelium. Subsequently, two groups were administered subconjunctival injection of lipoplexes carrying plasmid DNA encoding for human GABPα/β or an empty plasmid DNA at 1-week intervals. The third group served as an experimental control. In vivo delivery of human GABPα/β into mouse neovascularized cornea reduced VEGF and Robo4 gene expression. Biomicroscopic examination showed that, at 1 week after one or two injections, GABPα/β-treated eyes had significantly less neovascularized corneal area than did eyes treated with the empty vector. Histologic examination showed significantly less vascularized area and fewer blood vessels in the GABP-treated group at 1 week after injections. However, these angiosuppressive effects were weakened at 2 weeks after injections. Our results indicate that subconjunctival GABP gene delivery delays corneal neovascularization for up to 2 weeks in a mouse model of deliberate corneal injury.Gene Therapy (2009) 16, 973–981; doi:10.1038/gt.2009.50; published online 7 May 2009