Supramolecular Cl⋅⋅⋅H and O⋅⋅⋅H Interactions in Self‐Assembled 1,5‐Dichloroanthraquinone Layers on Au(111)

Noh, Seung‐,Kyun,Jeon, Jeong Heum,Jang, Won Jun,Kim, Howon,Lee, Soon‐,Hyeong,Lee, Min Wook,Lee, Jhinhwan,Han, Seungwu,Kahng, Se‐,Jong WILEY‐VCH Verlag 2013 CHEMPHYSCHEM -WEINHEIM- Vol.14 No.6

<P><B>Abstract</B></P><P>The role of halogen bonds in self‐assembled networks for systems with Br and I ligands has recently been studied with scanning tunneling microscopy (STM), which provides physical insight at the atomic scale. Here, we study the supramolecular interactions of 1,5‐dichloroanthraquinone molecules on Au(111), including Cl ligands, by using STM. Two different molecular structures of chevron and square networks are observed, and their molecular models are proposed. Both molecular structures are stabilized by intermolecular Cl⋅⋅⋅H and O⋅⋅⋅H hydrogen bonds with marginal contributions from Cl‐related halogen bonds, as revealed by density functional theory calculations. Our study shows that, in contrast to Br‐ and I‐related halogen bonds, Cl‐related halogen bonds weakly contribute to the molecular structure due to a modest positive potential (σ hole) of the Cl ligands.</P>

Transparent Nanoscale Floating Gate Memory Using Self‐Assembled Bismuth Nanocrystals in Bi₂Mg_2/3Nb_4/3O₇ (BMN) Pyrochlore Thin Films Grown at Room Temperature

Jung, Hyun‐,June,Yoon, Soon‐,Gil,Hong, Soon‐,Ku,Lee, Jeong‐,Yong WILEY‐VCH Verlag 2012 Advanced Materials Vol.24 No.25

<P><B>Bismuth nanocrystals</B> for a nanoscale floating gate memory device are self‐assembled in Bi<SUB>2</SUB>Mg<SUB>2/3</SUB>Nb<SUB>4/3</SUB>O<SUB>7</SUB> (BMN) dielectric films grown at room temperature by radio‐frequency sputtering. The TEM cross‐sectional image shows the “real” structure grown on a Si (001) substrate. The image magnified from the dotted box (red color) in the the cross‐sectional image clearly shows bismuth nanoparticles at the interface between the Al<SUB>2</SUB>O<SUB>3</SUB> and HfO<SUB>2</SUB> layer (right image). Nanoparticles approximately 3 nm in size are regularly distributed at the interface.</P>

Organic Thin‐Film Transistors: Simultaneous Modification of Bottom‐Contact Electrode and Dielectric Surfaces for Organic Thin‐Film Transistors Through Single‐Component Spin‐Cast Monolayers (Adv. Funct. Mater. 8/2011)

Acton, Orb,Dubey, Manish,Weidner, Tobias,O’Malley, Kevin M.,Kim, Tae‐,Wook,Ting, Guy G.,Hutchins, Daniel,Baio, J. E.,Lovejoy, Tracy C.,Gage, Alexander H.,Castner, David G.,Ma, Hong,Jen, Alex K.& WILEY‐VCH Verlag 2011 Advanced functional materials Vol.21 No.8

<P><B>Abstract</B></P><P>An efficient process is developed by spin‐coating a single‐component, self‐assembled monolayer (SAM) to simultaneously modify the bottom‐contact electrode and dielectric surfaces of organic thin‐film transistors (OTFTs). This effi cient interface modifi cation is achieved using <I>n</I>‐alkyl phosphonic acid based SAMs to prime silver bottom‐contacts and hafnium oxide (HfO<SUB>2</SUB>) dielectrics in low‐voltage OTFTs. Surface characterization using near edge X‐ray absorption fi ne structure (NEXAFS) spectroscopy, X‐ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, atomic force microscopy (AFM), and spectroscopic ellipsometry suggest this process yields structurally well‐defi ned phosphonate SAMs on both metal and oxide surfaces. Rational selection of the alkyl length of the SAM leads to greatly enhanced performance for both <I>n</I>‐channel (C<SUB>60</SUB>) and p‐channel (pentacene) based OTFTs. Specifi cally, SAMs of <I>n</I>‐octylphos‐phonic acid (OPA) provide both low‐contact resistance at the bottom‐contact electrodes and excellent interfacial properties for compact semiconductor grain growth with high carrier mobilities. OTFTs based on OPA modifi ed silver electrode/HfO<SUB>2</SUB> dielectric bottom‐contact structures can be operated using < 3V with low contact resistance (down to 700 Ohm‐cm), low subthreshold swing (as low as 75 mV dec<SUP>−1</SUP>), high on/off current ratios of 107, and charge carrier mobilities as high as 4.6 and 0.8 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, for C60 and pentacene, respectively. These results demonstrate that this is a simple and efficient process for improving the performance of bottom‐contact OTFTs.</P>

Polyrotaxaned versus Interdigitated Super‐Arrays of Loop‐and‐Chain Strands: Role of the Anion in Formation of Silver(0) Particles

Jang, Jaeseong,Noh, Tae Hwan,Park, Jin Kyoon,Shim, Yoon‐,Bo,Jung, Ok‐,Sang WILEY‐VCH Verlag 2014 European journal of inorganic chemistry Vol.2014 No.32

<P><B>Abstract</B></P><P>Self‐assembly of AgX (X<SUP>–</SUP> = BF<SUB>4</SUB><SUP>–</SUP>, ClO<SUB>4</SUB><SUP>–</SUP>, and NO<SUB>3</SUB><SUP>–</SUP>) with <I>C</I><SUB>3</SUB>‐symmetric 1,3,5‐tris(isonicotinoyloxyethyl)cyanurate (<B>L</B>) yields 1D loop‐and‐chain strands. However, the formation of a super‐array of strands depends on the nature of the polyatomic anions: BF<SUB>4</SUB><SUP>–</SUP> and ClO<SUB>4</SUB><SUP>–</SUP> anions induce 1D polyrotaxaned loop‐and‐chain strands, whereas NO<SUB>3</SUB><SUP>–</SUP> anion leads to the formation of 2D‐like interdigitated loop‐and‐chain strands in the crystalline state. Calcination of [Ag<SUB>3</SUB>(<B>L</B>)<SUB>2</SUB>]3X (X<SUP>–</SUP> = BF<SUB>4</SUB><SUP>–</SUP> and NO<SUB>3</SUB><SUP>–</SUP>) crystals at 500 °C produces silver(0) particles, whereas the same treatment of [Ag<SUB>3</SUB>(<B>L</B>)<SUB>2</SUB>]3ClO<SUB>4</SUB> crystals affords a mixture of silver(0) and silver(I) chloride. The rates of formation of Ag<SUP>0</SUP> nanoparticles by reduction of crystalline products using ascorbic acid are in the order X<SUP>–</SUP> = ClO<SUB>4</SUB><SUP>–</SUP> > BF<SUB>4</SUB><SUP>–</SUP> > NO<SUB>3</SUB><SUP>–</SUP>, and their crystalline morphologies are dependent on the nature of the polyatomic anions.</P>

Nanotransfer Printing with sub‐10 nm Resolution Realized using Directed Self‐Assembly

Jeong, Jae Won,Park, Woon Ik,Do, Lee‐,Mi,Park, Jong‐,Hyun,Kim, Tae‐,Heon,Chae, Geesung,Jung, Yeon Sik WILEY‐VCH Verlag 2012 ADVANCED MATERIALS Vol.24 No.26

<P><B>An extraordinarily facile sub‐10 nm fabrication method</B> using the synergic combination of nanotransfer printing and the directed self‐assembly of block copolymers is introduced. The approach is realized by achieving the uniform self‐assembly of polydimethylsiloxane (PDMS)‐containing block copolymers on a PDMS mold through the stabilization of the block copolymer thin films. This simple printing method can be applied on oxides, metals, polymers, and non‐planar substrates without pretreatments. The fabrication of well‐aligned metallic and polymeric functional nanostructures and crossed wire structures is also presented.</P>

Immunosensor Based on Electrogenerated Chemiluminescence Using Ru(bpy)₃²⁺‐Doped Silica Nanoparticles and Calix[4]crown‐5 Self‐Assembled Monolayers

Kim, Yang‐,Rae,Seo, Hyo‐,Ju,Oh, Jeong‐,Wook,Lim, Hyunchang,Kim, Tae Hyun,Kim, Hasuck WILEY‐VCH Verlag 2013 Electroanalysis Vol.25 No.4

<P><B>Abstract</B></P><P>An electrogenerated chemiluminescence (ECL)‐based immunosensor for the detection of immunoglobulin G (IgG) has been fabricated using Ru(bpy)<SUB>3</SUB><SUP>2+</SUP>‐doped silica nanoparticles and calix[4]crown‐5 self‐assembled monolayers (SAMs). Ru(bpy)<SUB>3</SUB><SUP>2+</SUP>‐doped silica nanoparticles are prepared by the water‐in‐oil (W/O) microemulsion method. ProLinker B, a commercially available thiolated calix[4]crown‐5 derivative, is utilized for the immobilization of anti‐immunoglobulin G (Anti‐IgG) on a gold electrode. The concentration of IgG is measured using a sandwich‐type ECL immunosensor based on the proposed immunosensor. The ECL intensity is linearly proportional to the IgG concentration over the concentration range 5–30 µg mL<SUP>−1</SUP>. The detection limit of IgG is 1.5 µg mL<SUP>−1</SUP>.</P>

Conservation of <i>Hox</i> gene clusters in the self‐fertilizing fish <i>Kryptolebias marmoratus</i> (Cyprinodontiformes; Rivulidae)

Kim, B.‐,M.,Lee, B.‐,Y.,Lee, J.‐,H.,Rhee, J.‐,S.,Lee, J.‐,S. Blackwell Publishing Ltd 2016 Journal of fish biology Vol.88 No.3

<P>In this study, whole <I>Hox</I> gene clusters in the self‐fertilizing mangrove killifish <I>Kryptolebias marmoratus</I> (Cyprinodontiformes; Rivulidae), a unique hermaphroditic vertebrate in which both sex organs are functional at the same time, were identified from whole genome and transcriptome sequences. The aim was to increase the understanding of the evolutionary status of conservation of this <I>Hox</I> gene cluster across fish species.</P>

Effects of self‐ligating brackets on the surfaces of stainless steel wires following clinical use: AFM investigation

CHOI, S.,JOO, H.‐,J.,CHEONG, Y.,PARK, Y.‐,G.,PARK, H.‐,K. Blackwell Publishing Ltd 2012 Journal of microscopy Vol.246 No.1

<P><B>Summary</B></P><P>In orthodontic treatment, the frictional force between the archwire and bracket reduces the effectiveness of orthodontic treatment. The frictional force is affected not only by the geometry of the self‐ligating brackets but also by physical changes between the bracket slots and archwire surfaces during sliding movement. This study examined quantitatively the effect of self‐ligating treatments on the surfaces of stainless steel (SS) archwires during tooth movement <I>in vivo</I> by atomic force microscopy. Orthodontic 0.019″ × 0.025″ SS archwires after clinical use with the first bicuspid‐extraction treatment were employed using the Damon 3MX<SUP>®</SUP> SS self‐ligating brackets, Clippy‐C<SUP>®</SUP> ceramic self‐ligating brackets, and Kosaka<SUP>®</SUP> SS brackets. Intact SS archwires were used as the control group. All SS archwires after clinical use showed severe scratches and significantly higher roughness caused by frictional interactions between the brackets and archwires (<I>p</I> < 0.0001 vs. control). The descending order of surface roughness was the SS archwires treated, with ceramic self‐ligating brackets, with conventional SS brackets, and with SS self‐ligating brackets (<I>p</I> < 0.001). These findings suggest that an orthodontic treatment with SS self‐ligating brackets may require smaller orthodontic forces than that with ceramic self‐ligating brackets or conventional SS brackets.</P>

Exploring pathways for socio‐economic inequalities in self‐reported oral symptoms among Korean adolescents

Jung, Se‐,Hwan,Watt, Richard G.,Sheiham, Aubrey,Ryu, Jae‐,In,Tsakos, Georgios Blackwell Publishing Ltd 2011 community dentistry and oral epidemiology Vol.39 No.3

<P>Jung S‐H, Watt RG, Sheiham A, Ryu J‐I, Tsakos G. Exploring pathways for socio‐economic inequalities in self‐reported oral symptoms among Korean adolescents. Community Dent Oral Epidemiol 2011; 39: 221–229. © 2010 John Wiley & Sons A/S</P><P><B>Abstract – </B><B> Objective: </B> This study aimed to assess socio‐economic inequalities in self‐reported oral symptoms in Korean adolescents and to assess the association of health behaviours, psychosocial factors and material factors on social gradients in oral symptoms.</P><P><B>Method: </B> Cross‐sectional data were from the national 2007 Korean Youth Risk Behavior Web‐based Survey (KYRBWS). Self‐reported oral symptoms included toothache, bad breath, and fractured teeth. Self‐assessed socio‐economic status (SES) was selected as a measure of SES. To assess socio‐economic inequalities in oral symptoms, we used logistic regression models for toothache, bad breath and fractured teeth, and ordinal logistic regression models for the aggregate variable on oral symptoms. We used models adjusting for socio‐demographic factors (Model 1) and compared them to models additionally adjusting for health behaviours (Model 2), psychosocial factors (Model 3) and material factors (Model 4).</P><P><B>Results: </B> A total of 78 834 students were invited to participate, and the response rate was 94.8% (<I>n</I> = 74 698). We found that lower self‐assessed SES was significantly associated with higher prevalence of each of the three self‐reported oral symptoms. Social gradient in the prevalence of each oral symptoms persisted when adjusted for behavioural, psychosocial and material factors. The odds ratio (OR) for the aggregate variable on oral symptoms in the lower SES group was 2.25 (95% CI 2.04, 2.49), and the respective figures after adjusting for behavioural, psychosocial and material factors were 2.17 (95% CI 1.96, 2.39), 1.90 (95% CI 1.73, 2.10) and 2.26 (95% CI 2.04, 2.50). While adjusting for psychosocial factors decreased the OR in the aggregate variable on oral symptoms for lower SES groups, adjusting for health behaviours and material factors hardly changed the OR.</P><P><B>Conclusion: </B> There were clear social gradients in three self‐reported oral symptoms (toothache, bad breath and fractured teeth) in Korean adolescents. Psychosocial factors explained part of the social inequalities in oral symptoms. Future longitudinal research is required to better address the pathways that explain socio‐economic inequalities in oral symptoms during adolescence.</P>

Self‐Propagating Domino‐like Reactions in Oxidized Graphite

Kim, Franklin,Luo, Jiayan,Cruz‐,Silva, Rodolfo,Cote, Laura J.,Sohn, Kwonnam,Huang, Jiaxing WILEY‐VCH Verlag 2010 Advanced Functional Materials Vol.20 No.17

<P><B>Abstract</B></P><P>Graphite oxide (GO) has received extensive interest as a precursor for the bulk production of graphene‐based materials. Here, the highly energetic nature of GO, noted from the self‐propagating thermal deoxygenating reaction observed in solid state, is explored. Although the resulting graphene product is quite stable against combustion even in a natural gas flame, its thermal stability is significantly reduced when contaminated with potassium salt by‐products left from GO synthesis. In particular, the contaminated GO becomes highly flammable. A gentle touch with a hot soldering iron can trigger violent, catastrophic, total combustion of such GO films, which poses a serious fire hazard. This highlights the need for efficient sample purification methods. Typically, purification of GO is hindered by its tendency to gelate as the pH value increases during rinsing. A two‐step, acid–acetone washing procedure is found to be effective for suppressing gelation and thus facilitating purification. Salt‐induced flammability is alarming for the fire safety of large‐scale manufacturing, processing, and storage of GO materials. However, the energy released from the deoxygenation of GO can also be harnessed to drive new reactions for creating graphene‐based hybrid materials. Through such domino‐like reactions, graphene sheets decorated with metal and metal oxide particles are synthesized using GO as the in situ power source. Enhanced electrochemical capacitance is observed for graphene sheets loaded with RuO<SUB>2</SUB> nanoparticles.</P>