Business Groups and Tunneling: Evidence from Brand Royalty Flows within Chaebol

This paper investigates the intragroup flows of brand royalties within large Korean business groups. We find that business group member firms pay a greater amount of brand royalties when the associated business groups adopt a holding company governance structure, consistent with the public allegation that chaebols tunnel wealth from member firms to holding companies that they directly control. However, member firms pay a smaller amount of brand royalties when their related party transactions (RPTs) are monitored, for example, when the firm is on (i) the watch list of an external watchdog agency for controlling shareholders’ unfair profit reaping from RPTs or when its board of directors internally operates (ii) a designated committee on RPTs or (iii) an audit committee. The results suggest that the alleged tunneling behavior of large business groups can be mitigated by external or internal monitoring on RPTs

Fabrication of highly ordered multilayer thin films and its applications

A new method is introduced to build up organic/organic multilayer films composed of cationic poly(allylamine hydrochloride) (PAH) and negatively charged poly(sodium 4-styrenesulfonate) (PSS) by using the spinning process. The adsorption process is governed by both the viscous force induced by fast solvent elimination and the electrostatic interaction between oppositely charged species. On the other hand, the centrifugal and air shear forces applied by the spinning process significantly enhance the desorption of weakly bound polyelectrolyte chains and also induce the planarization of the adsorbed polyelectrolyte layer. The film thickness per bilayer adsorbed by the conventional dipping process and the spinning process was found to be about 4 å and 24 å, respectively. The surface of the multilayer films prepared with the spinning process is quite homogeneous and smooth. Electroluminescence (EL) devices composed of alternating poly(p-phenylene vinylene) (PPV) and polyanions films show higher quantum efficiency when prepared by the spin self-assembly (SA) method.This work was financially supported by the National Research Laboratory Program (Grant M1-0104-00-0191) and funded in part by the Ministry of Education through the Brain Korea 21 Program at Seoul National University

Spin-coated ultrathin multilayers and their micropatterning using microfluidic channels

A new method is introduced to build up organic/organic multilayer films composed of cationic poly(allylamine hydrochloride) (PAH) and negatively charged poly (sodium 4-styrenesulfonate) (PSS) using the spinning process. The adsorption process is governed by both the viscous force induced by fast solvent elimination and the electrostatic interaction between oppositely charged species. On the other hand, the centrifugal and air shear forces applied by the spinning process significantly enhances desorption of weakly bound polyelectrolyte chains and also induce the planarization of the adsorbed polyelectrolyte layer. The film thickness per bilayer adsorbed by the conventional dipping process and the spinning process was found to be about 4 Å and 24 Å, respectively. The surface of the multilayer films prepared with the spinning process is quite homogeneous and smooth. Also, a new approach to create multilayer ultrathin films with welldefined micropatterns in a short process time is introduced. To achieve such micropatterns with high line resolution in organic multilayer films, microfluidic channels were combined with the convective self-assembly process employing both hydrogen bonding and electrostatic intermolecular interactions. The channels were initially filled with polymer solution by capillary pressure and the residual solution was then removed by the spinning process.This work was financially supported by the National Research Laboratory Program (Grant M1-0104-00-0191) and funded in part by the Ministry of Education through the Brain Korea 21 Program at Seoul National University

Ion‐Specific Oil Repellency of Polyelectrolyte Multilayers in Water: Molecular Insights into the Hydrophilicity of Charged Surfaces

Surface wetting on polyelectrolyte multilayers (PEMs), prepared by alternating deposition of polydiallyldimethylammonium chloride (PDDA) and poly(styrene sulfonate) (PSS), was investigated mainly in water‐solid‐oil systems. The surface‐wetting behavior of as‐prepared PEMs was well correlated to the molecular structures of the uncompensated ionic groups on the PEMs as revealed by sum frequency generation vibrational and X‐ray photoelectron spectroscopies. The orientation change of the benzenesulfonate groups on the PSS‐capped surfaces causes poor water wetting in oil or air and negligible oil wetting in water, while the orientation change of the quaternized pyrrolidine rings on the PDDA‐capped surfaces hardly affects their wetting behavior. The underwater oil repellency of PSS‐capped PEMs was successfully harnessed to manufacture highly efficient filters for oil‐water separation at high flux.Wet surfaces: Liquid wetting on charged surfaces is well correlated with the molecular nature of surface ionic groups. The orientation change of surface ionic groups either hardly affects water wetting if their configuration is isotropic, or markedly transforms poor water wetting in oil to poor water de‐wetting in water if their configuration is anisotropic, thus leading to excellent underwater oil repellency.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111271/1/anie_201411992_sm_miscellaneous_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/111271/2/4851_ftp.pd

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Thermally Stable Antireflective Coatings Based on Nanoporous Organosilicate Thin Films

Thermally stable nanoporous organosilicate thin films were realized by the microphase separation of pore-generating polymers mixed with an organosilicate matrix to be antireflective coatings (ARCs), for which a thin film with a refractive index (n) of 1.23 for zero reflection is required. The refractive index of such nanoporous organosilicate films can be tuned from 1.39 down to 1.23 by incorporating nanopores within the films. With a nanoporous single layer with n ~ 1.23, the light transmittance of the glass above 99.8% was achieved in the visible range (λ ~ 550 nm). To overcome the limitation on the narrow wavelength for high transmittance imposed by a single antireflective nanoporous thin film, bilayer thin films with different refractive indices were prepared by placing a high refractive index layer with a refractive index of 1.45 below the nanoporous thin film. UV−vis transmittance of a glass coated with the bilayer films was compared with nanoporous single-layer films and it is demonstrated that the novel broadband antireflection coatings in a wide range of visible wavelength can be easily obtained by the organosilicate bilayer thin films described in this study. Also, ARCs developed in this study demonstrate excellent AR durability owing to the hydrophobic nature of the organosilicate matrix.This work was supported by the NANO Systems Institute - National Core Research Center (NSI-NCRC) from the Korea Science and Engineering Foundation (KOSEF) and the Brain Korea 21 Program endorsed by the Ministry of Education of Korea. We are very grateful to Mr. Y. J. Park at Postech for assistance during X-ray reflectivity experiments at Pohang Light Source (PLS) supported by the Ministry of Science and Technology of Korea.Wealso thank Dr. Steve Kline (NIST), Prof. S.-M. Choi, and Mr. J. Lee for their help during smallangle neutron scattering experiments at the National Institute of Standards and Technology (NIST) in the United States. J.C. acknowledges the financial support from the ERC Program of the MOST/ KOSEF (R11-2005-048-00000-0)

Change in the quantum efficiency due to relative thickness variation of hole transport and emitting layers in a self-assembled device

Using (Poly(phenylene vinylene) (PPV)/Poly(styrene sulfonate) (PSS)) and (PPV/Poly(methacrylic acid) (PMA)) self-assembled bilayers exhibiting different hole transport properties, we investigated the competing effect on quantum efficiency of the variation of relative thicknesses of (PPV/PSS) and (PPV/PMA) bilayers in indium tin oxide (ITO)/(PPV/PSS)n/(PPV/PMA)m/Al devices with fixed 20 bilayers (i.e. n+m=20). The (PPV/PSS) bilayer is known to be better as a hole transport layer due to higher leakage current and lower quantum efficiency in comparison with the (PPV/PMA) emitting bilayers. With increasing the number of (PPV/PSS) bilayers from 0 to 20 bilayers, the quantum efficiency of the multilayer self-assembled device was at maximum with 3 bilayers of (PPV/PSS) in contact with the ITO anode and the efficiency montonically decreased upon further increase of the (PPV/PSS) bilayer above 3. In the case of the increase of (PPV/PSS) bilayer thickness by the addition of NaCl salt to the PSS solution during the layer deposition process, the quantum efficiency of the device was significantly improved and also maximized with the 3 (PPV/PSS) bilayers. The significant change on the quantum efficiency by a simple control of relative bilayer numbers is mainly attributed to the competing effects caused by the increase of hole transport (PPV/PSS) bilayer at the expense of reduced emitting (PPV/PMA) bilayer. It was also found that the enhancement of the quantum efficiency by the addition of NaCl salt to the PSS solution is mainly caused by sufficient surface coverage of the (PPV/PSS) hole transport bilayers on the ITO electrode.This work was supported by the National Research Laboratory Fund (Grant number: M1-0104-00-0191) from the Ministry of Science and Technology (MOST) and by the Ministry of Education through the Brain Korea 21 Program at Seoul National University

Transparent Conducting Oxide Electrodes: Layer‐by‐Layer Assembled Oxide Nanoparticle Electrodes with High Transparency, Electrical Conductivity, and Electrochemical Activity by Reducing Organic Linker‐Induced Oxygen Vacancies (Small 8/2020)

Solution-processable transparent conducting oxide (TCO) nanoparticle (NP)–based electrodes are limited by their low electrical conductivity, which originates from the low level of oxygen vacancies within NPs and the contact resistance between neighboring NPs. Additionally, these electrodes suffer from the troublesome trade-off between electrical conductivity and optical transmittance and the restricted shape of substrates (i.e., only flat substrates). An oxygen-vacancy-controlled indium tin oxide (ITO) NP-based electrode is introduced using carbon-free molecular linkers with strong chemically reducing properties. Specifically, ITO NPs are layer-by-layer assembled with extremely small hydrazine monohydrate linkers composed of two amine groups, followed by thermal annealing. This approach markedly improves the electrical conductivity of ITO NP-based electrodes by significantly increasing the level of oxygen vacancies and decreasing the interparticle distance (i.e., contact resistance) without sacrificing optical transmittance. The prepared electrodes surpass the optical/electrical performance of TCO NP-based electrodes reported to date. Additionally, the nanostructured ITO NP films can be applied to more complex geometric substrates beyond flat substrates, and furthermore exhibit a prominent electrochemical activity. This approach can provide an important basis for developing a wide range of highly functional transparent conducting electrodes. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim1

Nanoporous Block Copolymer Micelle/Micelle Multilayer Films with Dual Optical Properties

We introduce a novel and versatile approach for preparing self-assembled nanoporous multilayered films with tunable optical properties. Protonated polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and anionic polystyrene-block-poly(acrylic acid) (PS-b-PAA) block copolymer micelles (BCM) were used as building blocks for the layer-by-layer assembly of BCM multilayer films. BCM film growth is governed by electrostatic and hydrogen-bonding interactions between the opposite BCMs. Both film porosity and film thickness are dependent upon the charge density of the micelles, with the porosity of the film controlled by the solution pH and the molecular weight (Mw) of the constituents. PS7K-b-P4VP28K/PS2K-b-PAA8K films prepared at pH 4 (for PS7K-b-P4VP28K) and pH 6 (for PS2K-b-PAA8K) are highly nanoporous and antireflective. In contrast, PS7K-b-P4VP28K/PS2K-b-PAA8K films assembled at pH 4/4 show a relatively dense surface morphology due to the decreased charge density of PS2K-b-PAA8K. Films formed from BCMs with increased PS block and decreased hydrophilic block (P4VP or PAA) size (e.g., PS36K-b-P4VP12K/PS16K-b-PAA4K at pH 4/4) were also nanoporous. This is attributed to a decrease in interdigitation between the adjacent corona shells of the low Mw BCMs, thus creating more void space between the micelles. Multilayer films with antireflective and photochromic properties were obtained by incorporating a water-insoluble photochromic dye (spiropyran) into the hydrophobic PS core of the BCMs assembled in the films. The optical properties of these films can be modulated by UV irradiation to selectively and reversibly control the transmission of light. Light transmission of higher than 99% was observed with accompanying photochromism in the (PS7K-b-P4VP28K/PS2K-b-PAA8K) multilayer films assembled at pH 4/6. Our approach highlights the potential to incorporate a range of materials, ranging from conventional hydrophilic materials with specific interactions to hydrophobic compounds, into the assembled BCMs to yield multifunctional nanoporous films.This work was supported by the Ministry of Education through the Brain Korea 21 Program at Seoul National University and the National Research Laboratory Program (Grant M1-0104-00-0191). Additionally, this work was supported by the SRC/ERC Program of the MOST/KOSEF (R11-2005-048-00000-0), the Seoul Science Fellowship, and the Australian Research Council under the Discovery Project and Federation Fellowship Schemes