미국 원자력산업의 활성화 전망

Colvin Joe F. 한국원자력산업회의 1998 원자력산업 Vol.18 No.4

Fabricating Using Nano-particulates with Direct Write Technology

Sears James,Colvin Jacob,Carter Michael 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

Modern business trends call for miniaturization of electronic systems. One of the major impedances in this miniaturization is the conductive and inductive components in chips and circuit boards. Direct Write Technology can write these soft magnetic materials, thus allowing for further miniaturization of inductor devices. Another obstacle in electronics fabrication is the size limitations of thick screen-printing and the material limitations in ink jet printing. Direct Write Technologies address both of these limitations by providing feature sizes less than 20 microns with a wide range of materials possibilities. A discussion of the application of these nano-particulate materials by Direct Write Technologies will be presented.

Nuclear Pore Complex Protein Sequences Determine Overall Copolymer Brush Structure and Function

Ando, D.,Zandi, R.,Kim, Y.,Colvin, M.,Rexach, M.,Gopinathan, A. Biophysical Society ; Published for the Biophysica 2014 Biophysical journal Vol.106 No.9

The transport of cargo across the nuclear membrane is highly selective and accomplished by a poorly understood mechanism involving hundreds of nucleoporins lining the inside of the nuclear pore complex (NPC). Currently, there is no clear picture of the overall structure formed by this collection of proteins within the pore, primarily due to their disordered nature. We perform coarse-grained simulations of both individual nucleoporins and grafted rings of nups mimicking the in vivo geometry of the NPC and supplement this with polymer brush modeling. Our results indicate that different regions or blocks of an individual NPC protein can have distinctly different forms of disorder and that this property appears to be a conserved functional feature. Furthermore, this block structure at the individual protein level is critical to the formation of a unique higher-order polymer brush architecture that can exist in distinct morphologies depending on the effective interaction energy between the phenylalanine glycine (FG) domains of different nups. Because the interactions between FG domains may be modulated by certain forms of transport factors, our results indicate that transitions between brush morphologies could play an important role in regulating transport across the NPC, suggesting novel forms of gated transport across membrane pores with wide biomimetic applicability.

Tetrathiafulvalene Hetero Radical Cation Dimerization in a Redox-Active [2]Catenane

Wang, Cheng,Dyar, Scott M.,Cao, Dennis,Fahrenbach, Albert C.,Horwitz, Noah,Colvin, Michael T.,Carmieli, Raanan,Stern, Charlotte L.,Dey, Sanjeev K.,Wasielewski, Michael R.,Stoddart, J. Fraser American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.46

<P>The electronic properties of tetrathiafulvalene (TTF) can be tuned by attaching electron-donating or electron-withdrawing substituents. An electron-rich macrocyclic polyether containing two TTF units of different constitutions, namely 4,4′-bis(hydroxymethyl)tetrathiafulvalene (OTTFO) and 4,4′-bisthiotetrathiafulvalene (STTFS), has been synthesized. On two-electron oxidation, a hetero radical dimer is formed between OTTFO<SUP>•+</SUP> and STTFS<SUP>•+</SUP>. The redox behavior of the macrocyclic polyether has been investigated by electrochemical techniques and UV–vis and electron paramagnetic resonance (EPR) spectroscopies. The [2]catenane in which the macrocyclic polyether is mechanically interlocked with the cyclobis(paraquat-<I>p</I>-phenylene) (CBPQT<SUP>4+</SUP>) ring has also been prepared using template-directed protocols. In the case of the [2]catenane, the formation of the TTF hetero radical dimer is prevented sterically by the CBPQT<SUP>4+</SUP> ring. After a one-electron oxidation, a 70:30 ratio of OTTFO<SUP>•+</SUP> to STTFS<SUP>•+</SUP> is present at equilibrium, and, as a result, two translational isomers of the [2]catenane associated with these electronically different isomeric states transpire. EPR titration spectroscopy and simulations reveal that the radical states of the two constitutionally different TTF units in the [2]catenane still experience long-range electronic intramolecular coupling interactions, despite the presence of the CBPQT<SUP>4+</SUP> ring, when one or both of them are oxidized to the radical cationic state. These findings in the case of both the free macrocyclic polyether and the [2]catenane have led to a deeper fundamental understanding of the mechanism of radical cation dimer formation between constitutionally different TTF units.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-46/ja307577t/production/images/medium/ja-2012-07577t_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja307577t'>ACS Electronic Supporting Info</A></P>

Magnetic field controlled graphene oxide-based origami with enhanced surface area and mechanical properties

Park, Ok-Kyung,Tiwary, Chandra Sekhar,Yang,Bhowmick, Sanjit,Vinod, Soumya,Zhang, Qingbo,Colvin, Vicki L.,Asif, S. A. Syed,Vajtai, Robert,Penev, Evgeni S.,Yakobson, Boris I.,Ajayan, Pulickel M. The Royal Society of Chemistry 2017 Nanoscale Vol.9 No.21

Why Don’t Cancer Survivors Quit Smoking? An Evaluation of Readiness for Smoking Cessation in Cancer Survivors

Melissa A. Little,Robert C. Klesges,Zoran Bursac,Jon O. Ebbert,Jennifer P. Halbert,Andrew N. Dunkle,Lauren Colvin,Patricia J. Goedecke,Benny Weksler 대한암예방학회 2018 Journal of cancer prevention Vol.23 No.1

Background: Cancer survivors have a high rate of participation in cigarette-smoking cessation programs but their smoking-abstinence rates remain low. In the current study, we evaluated the readiness to quit smoking in a cancer-survivor population. Methods: Cross-sectional data survey conducted among 112 adult cancer survivors who smoked cigarettes in Tennessee. Analyses were conducted using a two-sample t-test, χ2 test, Fishers Exact test, and multivariable logistic regression with smoker’s readiness to quit as the dependent variable. We operationally defined a smoker not ready to quit as anyone interested in quitting smoking beyond the next 6 months or longer (or not at all), as compared to those that are ready to quit within the next 6 months. Results: Thirty-three percent of participants displayed a readiness to quit smoking in the next 30 days. Smokers ready to quit were more likely to display high confidence in their ability to quit (OR = 4.6; 95% CI, 2.1-9.7; P < 0.0001) than those not ready to quit. Those ready to quit were nearly five times more likely to believe smoking contributed to their cancer diagnosis (OR = 4.9; 95% CI, 1.1-22.6; P = 0.0432). Those ready to quit were also much more likely to attempt smoking cessation when diagnosed with cancer (OR = 8.9; 95% CI, 1.8-44.3; P = 0.0076) than smokers not ready to quit. Finally, those ready to quit were more likely to endorse smoking more in the morning than other times of the day, compared to those not ready to quit (OR = 7.9; 95% CI, 1.5-42,3; P = 0.0148), which increased odds of readiness to quit within the next 6 months. Conclusions: Despite high participation in smoking-cessation programs for cancer survivors, only one-third of participants were ready to quit. Future research is needed to develop programs targeting effective strategies promoting smoking cessation among cancer survivors who are both ready and not ready to quit smoking. (J Cancer Prev 2018;23:44-50)

A Novel, Reactive Green Iron Sulfide (Sulfide Green Rust) Formed on Iron Oxide Nanocrystals

Jones, Christopher J.,Chattopadhyay, Soma,Gonzalez-Pech, Natalia I.,Avendano, Carolina,Hwang, Nina,Lee, Seung Soo,Cho, Minjung,Ozarowski, Andrew,Prakash, Arjun,Mayo, J. T.,Yavuz, Cafer,Colvin, Vicki. American Chemical Society 2015 Chemistry of materials Vol.27 No.3

<P>Iron oxide nanocrystals are of great scientific and technological interest. In this work, these materials are the starting point for producing a reactive nanoparticle whose surface resembles that of natural green rusts. Treatment of iron oxide nanoparticles with cysteamine leads to the reduction of iron and the formation of a brilliant green aqueous solution of nanocrystals rich in iron(II). These materials remained crystalline with magnetic and structural features of the original iron oxide. However, new low-angle X-ray diffraction peaks as well as vibrational features characteristic of cysteamine were found in the nanocrystalline product. X-ray absorption spectroscopy (XAS), X-ray photoemission (XPS) and Mössbauer spectroscopies indicated the presence of an iron(II)-rich phase with high sulfur content analogous to the iron–oxygen structures found in natural green rusts. Electron microscopy found that these structural components remained associated with the nonreduced iron oxide cores. These sulfur-rich analogs of natural green rusts are highly reactive and were able to rapidly degrade a model organic dye in water. This observation suggests possible actuation with a cysteamine treatment of inert and magnetic iron oxide particles at the point-of-use for environmental remediation.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-3/cm5028942/production/images/medium/cm-2014-028942_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5028942'>ACS Electronic Supporting Info</A></P>