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Spectroscopic study of the radionuclide Na21 for the astrophysical F17(α,p)Ne20 reaction rate
Cha, S. M.,Chae, K. Y.,Ahn, S.,Bardayan, D. W.,Chipps, K. A.,Cizewski, J. A.,Howard, M. E.,Kozub, R. L.,Kwak, K.,Manning, B.,Matos, M.,O'Malley, P. D.,Pain, S. D.,Peters, W. A.,Pittman, S. T.,Ratkiewi American Physical Society 2017 Physical Review C Vol.96 No.2
<P>The Mg-24(p,alpha)Na-21 reaction was measured at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory to study the spectroscopy of the radionuclide Na-21. A 31-MeV proton beam from the 25 MV tandem accelerator bombarded isotopically enriched Mg-24 targets. Recoiling He-4 particles were identified by an annular silicon strip detector array. Two energy levels at E-x = 6.594 and 7.132 MeV were observed for the first time. By comparing the experimentally obtained angular distributions and distorted wave Born approximation calculations, the spins and parities of Na-21 energy levels were constrained. The astrophysicallyi-mportant F-17(alpha, p)Ne-20 reaction rate was also calculated for the first time using resonance parameters for 12 energy levels.</P>
Proton Decay of 21Na for 20Ne Energy Levels
Kim M. J.,Chae K. Y.,Cha S. M.,Ahn S. H.,Bardayan D. W.,Chipps K. A.,Cizewski J. A.,Howard M. E.,Manning B.,Ratkiewicz A.,Kozub R. L.,Kwak K.,Matos M.,O’Malley P. D.,Strauss S.,Pain S. D.,Pittman S. T 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.5
The 24Mg(p,α)21Na transfer reaction has been previously studied for a spectroscopic study of 21Na [Cha et al., Phys. Rev. C 96, 025810 (2017)]. In this follow-up analysis, the proton decays of the excited states of the radionuclide 21Na, which were measured simultaneously, are reported. By investigating the coincidence between the reaction α-particles and decay protons, we were able to identify three groups of events that are associated with the energy levels in 20Ne. The 20Ne excitation energy plot was obtained as a result. The four lowest known energy levels in 20Ne (the ground state and excited states at Ex = 1.633, 4.247 and 4.966 MeV) were clearly observed.
24Mg(p, α)21Na Reaction Study for Spectroscopy of 21Na
차수미,K. Y. Chae,김아람,E. J. Lee,S. Ahn,D. W. Bardayan,K. A. Chipps,J. A. Cizewski,M. E. Howard,B. Manning,P. D. O’Malley,A. Ratkiewicz,S. Strauss,R. L. Kozub,M. Matos,S. D. Pain,S. T. Pittman,M. S. Smith 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.8
The 24Mg(p, α)21Na reaction was measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory in order to better constrain the spins and parities of the energy levels in 21Na for the astrophysically important 17F(α, p)20Ne reaction rate calculation. 31-MeV proton beams from the 25-MV tandem accelerator and enriched 24Mg solid targets were used. Recoiling 4He particles from the 24Mg(p, α)21Na reaction were detected by a highly segmented silicon detector array which measured the yields of 4He particles over a range of angles simultaneously. A new level at 6661 ± 5 keV was observed in the present work. The extracted angular distributions for the first four levels of 21Na and the results from distorted wave Born approximation (DWBA) calculations were compared to verify and extract the angular momentum transfer.
Informing direct neutron capture on tin isotopes near the N=82 shell closure
Manning, B.,Arbanas, G.,Cizewski, J. A.,Kozub, R. L.,Ahn, S.,Allmond, J. M.,Bardayan, D. W.,Chae, K. Y.,Chipps, K. A.,Howard, M. E.,Jones, K. L.,Liang, J. F.,Matos, M.,Nesaraja, C. D.,Nunes, F. M.,O'M American Physical Society 2019 Physical Review C Vol.99 No.4
Howard, Paul,Day, Kathleen H.,Kim, Kyoon E.,Richardson, Jeanne,Thomas, James,Abraham,Irene,Fleischmann, Robert D.,Gottesman, Michael M.,Maurer, Richard A. 충남대학교부설 생명공학연구소 1992 생물공학연구지 Vol.2 No.-
The mechansims responsible for decreased levels of cAMP-dependent protein kinase activity in a mutant Chinese hamster ovary cell line have been examined. The cAMP-resistant Chinese hamster ovary 10260 cell line was found to possess only 20% of the cAMP-dependent protein kinase activity found in wild-type cells. The pressence of decreased concentrations of the catalytic subunit in these cells was confirmed through binding studies using a radiolabeled, heat-stable inhibitor of the kinase. Cloned Chinese hamster ovary catalytic subunit cDNAs were isolated, characterized, and used as hybridization probes to examine the relative concentrations of catalytic subunit mRNAs in the wild-type and 10260 cell lines. A 40-50% decrease in the concentration of the mRNA for the Cα isozyme of the catalytic subunit was observed in 10260 cells, as compared with wild-type. This decrease in catalytic subunit mRNA concentration probably accounts for a portion of the decreased kinase activity in the mutant cell. Further analysis of Cα mRNA by polymerase chain reaction confirmed the decreased expression of Cα mRNA in 10260 cells and further demonstrated the presence of two different species of Cα cDNAs was indistinguishable from the wild-type cDNA, but the other species was shorter. Nucleotide sequence analysis of the amplified cDNAs led to the identification of a 191-base pair deletion in the shorter cDNA. Gene transfer studies using wild-type and 10260 Cα cDNAs demonstrated wild-type activity, but the shorter cDNA was inactive. These studies suggest that at least two alternations in gene expression are responsible for decreased cAMP-dependent protein kinase activity in the 10260 cell line. One alteration results in an approximately 2-fold decrease in the concentrations of Cα mRNA in the cells.
Kim-Howard, Xana,Sun, Celi,Molineros, Julio E.,Maiti, Amit K.,Chandru, Hema,Adler, Adam,Wiley, Graham B.,Kaufman, Kenneth M.,Kottyan, Leah,Guthridge, Joel M.,Rasmussen, Astrid,Kelly, Jennifer,Sá Oxford University Press 2014 Human Molecular Genetics Vol.23 No.6
<P>Recent reports have associated <I>NCF2</I>, encoding a core component of the multi-protein NADPH oxidase (NADPHO), with systemic lupus erythematosus (SLE) susceptibility in individuals of European ancestry. To identify ethnicity-specific and -robust variants within <I>NCF2</I>, we assessed 145 SNPs in and around the <I>NCF2</I> gene in 5325 cases and 21 866 controls of European-American (EA), African-American (AA), Hispanic (HS) and Korean (KR) ancestry. Subsequent imputation, conditional, haplotype and bioinformatic analyses identified seven potentially functional SLE-predisposing variants. Association with non-synonymous rs17849502, previously reported in EA, was detected in EA, HS and AA (<I>P</I><SUB>EA</SUB> = 1.01 × 10<SUP>−54</SUP>, <I>P</I><SUB>HS</SUB> = 3.68 × 10<SUP>−10</SUP>, <I>P</I><SUB>AA</SUB> = 0.03); synonymous rs17849501 was similarly significant. These SNPs were monomorphic in KR. Novel associations were detected with coding variants at rs35937854 in AA (<I>P</I><SUB>AA</SUB> = 1.49 × 10<SUP>−9</SUP>), and rs13306575 in HS and KR (<I>P</I><SUB>HS</SUB> = 7.04 × 10<SUP>−7</SUP>, <I>P</I><SUB>KR</SUB> = 3.30 × 10<SUP>−3</SUP>). In KR, a 3-SNP haplotype was significantly associated (<I>P</I> = 4.20 × 10<SUP>−7</SUP>), implying that SLE predisposing variants were tagged. Significant SNP–SNP interaction (<I>P</I> = 0.02) was detected between rs13306575 and rs17849502 in HS, and a dramatically increased risk (OR = 6.55) with a risk allele at each locus. Molecular modeling predicts that these non-synonymous mutations could disrupt NADPHO complex assembly. The risk allele of rs17849501, located in a conserved transcriptional regulatory region, increased reporter gene activity, suggesting <I>in vivo</I> enhancer function. Our results not only establish allelic heterogeneity within <I>NCF2</I> associated with SLE, but also emphasize the utility of multi-ethnic cohorts to identify predisposing variants explaining additional phenotypic variance (‘missing heritability’) of complex diseases like SLE.</P>
Elucidating the mechanism of cellular uptake of fullerene nanoparticles
Yeonjeong Ha,Xianzhe Wang,Howard M. Liljestrand,Jennifer A. Maynard,Lynn E. Katz 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.2
Understanding the molecular interactions between biological cells and engineered nanoparticles is a key to evaluating potential toxicities to humans and the environment. This study developed a method to determine the mechanisms by which fullerene aggregates are distributed into a representative cell line, human intestinal Caco-2 cells. First, we determined that the presence of fetal bovine serum (FBS) in the cell culture media changes the particle characteristics and inhibits particle adsorptions onto cell surfaces. Second, significantly lower amounts of fullerene were internalized at 4°C, a temperature at which active transport mechanisms are effectively impeded, than at 37°C. Third, metabolic inhibitors of active transport and a microtubule transport inhibitor decreased fullerene uptake at 37°C. Fourth, cellular uptake of fullerene increased with increasing fullerene concentration, suggesting that passive diffusion into lipid membranes contributed to uptake over the broad concentration range used in this study. Together, these results indicate fullerene transport into cells occurs via two mechanisms: passive diffusion across the lipid bilayer and active transport including microtubule involved endocytosis. The results also suggest that simple physical-chemical partitioning models do not fully describe fullerene uptake, and instead, active transport models are also required to estimate the cellular uptake and toxicity of fullerene.
Genetic associations of LYN with systemic lupus erythematosus
Lu, R,Vidal, G S,Kelly, J A,Delgado-Vega, A M,Howard, X K,Macwana, S R,Dominguez, N,Klein, W,Burrell, C,Harley, I T,Kaufman, K M,Bruner, G R,Moser, K L,Gaffney, P M,Gilkeson, G S,Wakeland, E K,Li, Q-Z Macmillan Publishers Limited 2009 GENES AND IMMUNITY Vol.10 No.5
We targeted LYN, a src-tyosine kinase involved in B-cell activation, in case–control association studies using populations of European-American, African-American and Korean subjects. Our combined European-derived population, consisting of 2463 independent cases and 3131 unrelated controls, shows significant association with rs6983130 in a female-only analysis with 2254 cases and 2228 controls (P=1.1 × 10<SUP>−4</SUP>, odds ratio (OR)=0.81 (95% confidence interval: 0.73–0.90)). This single nucleotide polymorphism (SNP) is located in the 5′ untranslated region within the first intron near the transcription initiation site of LYN. In addition, SNPs upstream of the first exon also show weak and sporadic association in subsets of the total European-American population. Multivariate logistic regression analysis implicates rs6983130 as a protective factor for systemic lupus erythematosus (SLE) susceptibility when anti-dsDNA, anti-chromatin, anti-52 kDa Ro or anti-Sm autoantibody status were used as covariates. Subset analysis of the European-American female cases by American College of Rheumatology classification criteria shows a reduction in the risk of hematological disorder with rs6983130 compared with cases without hematological disorders (P=1.5 × 10<SUP>−3</SUP>, OR=0.75 (95% CI: 0.62−0.89)). None of the 90 SNPs tested show significant association with SLE in the African American or Korean populations. These results support an association of LYN with European-derived individuals with SLE, especially within autoantibody or clinical subsets.Genes and Immunity (2009) 10, 397–403; doi:10.1038/gene.2009.19; published online 16 April 2009
Chae, K.Y.,Ahn, S.,Ayres, A.,Bardayan, D.W.,Bey, A.,Greife, U.,Howard, M.E.,Jones, K.L.,Kozub, R.L.,Matoš,, M.,Moazen, B.H.,Nesaraja, C.D.,O’Malley, P.D.,Peters, W.A.,Pittman, S.T.,Smith, M.S. Elsevier 2018 Nuclear Instruments & Methods in Physics Research. Vol.900 No.-
<P><B>Abstract</B></P> <P>Direct measurements of ( α , p ) reactions of astrophysical interest with radioactive beams presents serious challenges because of the difficult nature of helium targets and the typical low intensities of the beams. To address this, a new technique has been developed for measurements of low-energy ( α , p ) reactions with heavy ion beams using an extended <SUP> 4 </SUP> He gas target and a newly developed gas recirculating system. The system was used to measure the <SUP> 4 </SUP> He(<SUP>19</SUP>F, <SUP> 1 </SUP> H)<SUP>22</SUP>Ne reaction as a demonstration. Excitation functions of the <SUP>19</SUP>F( α , p )<SUP>22</SUP>Ne and <SUP>19</SUP>F( α , <SUP> p ′ </SUP> )<SUP>22</SUP>Ne <SUP> ∗ </SUP> reactions were successfully measured to show the viability of this technique. Details of the approach and future plans are given.</P>