Oxidation-Mediated, Zwitterionic Polydopamine Coatings for Marine Antifouling Applications.

We synthesized a zwitterionic dopamine derivative ( ZW-DOPA) containing both catechol and amine groups, and we demonstrated an excellent marine antifouling surface by controlling the oxidation of ZW-DOPA. The oxidation was mediated by the deprotonation of catechol or the addition of an oxidant (ammonium persulfate (AP) or sodium periodate (NaIO4)). The oxidation and subsequent molecular transformation of ZW-DOPA was investigated over time by UV-vis spectroscopy. Among the different oxidation conditions tested, NaIO4-induced ZW-DOPA coating was the most efficient and successfully formed on various substrates, such as titanium dioxide, stainless steel, and nylon. Compared with uncoated substrates, ZW-DOPA-coated substrates showed high resistance to marine diatom adhesion. Considering the ease of use and substrate independence of the ZW-DOPA coating, this method shows promise as a basis for inhibiting marine fouling on a variety of substrates used in the marine industry and aquatic environments.

Surface Functionalization of Plastic Surfaces with Non-Biofouling Agarose Film to Develop a Chip-Based Platform.

We chemically functionalized several plastic surfaces using an agarose film for applying a protein chip. The chip performance was affected by the surface energy of each plastic after oxygen-plasma cleaning; as a result, polystyrene and polyethylene terephthalate showed a higher signal-to-noise ratio than did polypropylene. We envision that this study will help to develop a way to build biochips.

Immobilization of Antibody on a Cyclic Olefin Copolymer Surface with Functionalizable, Non-Biofouling Poly[Oligo(Ethylene Glycol) Methacrylate].

We report a perfluoroaryl azide-based photoreaction for synthesizing functionalizable and nonbiofouling poly[oligo(ethylene glycol) methacrylate] (pOEGMA) films on a chemically inert COC substrate, and an estimation of a surface coverage of the antibody immobilized onto the surface with the immuno-gold nanoparticles. The processes were confirmed by water contact angle measurement, FT-IR spectroscopy, and FE-SEM. The strategy demonstrated in this work could be applied to functionalizations of other polymeric materials and determination of the binding capacity of analytes in biosensors and microfluidic devices.

Determination of the Spatial Distribution of Air Pollutants in Bucheon, Republic of Korea, in Winter Using a GIS-Based Mobile Laboratory.

Driven by industrialization and urbanization, urban air pollution can increase respiratory, heart, and cerebrovascular diseases, and thus mortality rates; as such, it is necessary to improve air quality through the consideration of individual pollutants and emission sources. In Republic of Korea, national and local governments have installed urban and roadside air quality monitoring systems. However, stations are lacking outside metropolitan regions, and roadside stations are sparsely distributed, limiting comparisons of pollutant concentrations with vehicle traffic and floating population levels. Local governments have begun using mobile laboratories (MLs) to supplement the fixed measurement network and investigate road pollution source characteristics based on their spatiotemporal distribution; however, the collected data cannot be used effectively if they are not visualized. Here, we propose a method to collect and visualize global information system (GIS)-based air quality data overlayed with environmental variables to support air quality management measures. Spatiotemporal analyses of ML-derived data from Bucheon, Korea, confirmed that particulate and gaseous pollutant concentrations were high during typical commuting hours, at intersections, and at a specially managed road. During commuting hours, the maximum PM10 concentration reached 200.7 µg/m3 in the Nae-dong, Gyeongin-ro, and Ojeong-dong ready-mix concrete complex areas, and the maximum PM2.5 concentration was 161.7 µg/m3. The maximum NOx, NO2, and NO levels of 1.34 ppm, 0.18 ppm, and 1.18 ppm, respectively, were also detected during commuting hours. These findings support the need for targeted management of air pollution in this region, and highlight the benefit of comprehensively comparing road levels, driving speed, and traffic levels when identifying hotspots of air pollution. Such analyses will contribute to the development of air quality management measures customized to regional characteristics.

Controlled conjugated backbone twisting for an increased open-circuit voltage while having a high short-circuit current in poly(hexylthiophene) derivatives.

Conjugated polymers with nearly planar backbones have been the most commonly investigated materials for organic-based electronic devices. More twisted polymer backbones have been shown to achieve larger open-circuit voltages in solar cells, though with decreased short-circuit current densities. We systematically impose twists within a family of poly(hexylthiophene)s and examine their influence on the performance of polymer:fullerene bulk heterojunction (BHJ) solar cells. A simple chemical modification concerning the number and placement of alkyl side chains along the conjugated backbone is used to control the degree of backbone twisting. Density functional theory calculations were carried out on a series of oligothiophene structures to provide insights on how the sterically induced twisting influences the geometric, electronic, and optical properties. Grazing incidence X-ray scattering measurements were performed to investigate how the thin-film packing structure was affected. The open-circuit voltage and charge-transfer state energy of the polymer:fullerene BHJ solar cells increased substantially with the degree of twist induced within the conjugated backbone--due to an increase in the polymer ionization potential--while the short-circuit current decreased as a result of a larger optical gap and lower hole mobility. A controlled, moderate degree of twist along the poly(3,4-dihexyl-2,2':5',2''-terthiophene) (PDHTT) conjugated backbone led to a 19% enhancement in the open-circuit voltage (0.735 V) vs poly(3-hexylthiophene)-based devices, while similar short-circuit current densities, fill factors, and hole-carrier mobilities were maintained. These factors resulted in a power conversion efficiency of 4.2% for a PDHTT:[6,6]-phenyl-C(71)-butyric acid methyl ester (PC(71)BM) blend solar cell without thermal annealing. This simple approach reveals a molecular design avenue to increase open-circuit voltage while retaining the short-circuit current.

In situ hetero end-functionalized polythiophene and subsequent "click" chemistry with DNA.

It is demonstrated that bifunctionalized polythiophenes involving thiol and azide end-functional groups can be synthesized by chain-growth Suzuki-Miyaura type polymerization. The bifunctionalized polythiophenes are successfully characterized by 1H NMR, gel permeation chromatography (GPC), and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF). Furthermore, the azide end-group reacts with DNA via "click chemistry" to form a polythiophene/DNA hybrid structure, which is characterized by ESI-MS. The described synthetic approaches will lead to the synthesis of novel multi-block copolymers as well as biomolecule-based conjugated polymer structures.

3,4-Disubstituted polyalkylthiophenes for high-performance thin-film transistors and photovoltaics.

We demonstrate that poly(3,4-dialkylterthiophenes) (P34ATs) have comparable transistor mobilities (0.17 cm(2) V(-1) s(-1)) and greater environmental stability (less degradation of on/off ratio) than regioregular poly(3-alkylthiophenes) (P3ATs). Unlike poly(3-hexylthiophene) (P3HT), P34ATs do not show a strong and distinct π-π stacking in X-ray diffraction. This suggests that a strong π-π stacking is not always necessary for high charge-carrier mobility and that other potential polymer packing motifs in addition to the edge-on structure (π-π stacking direction parallel to the substrate) can lead to a high carrier mobility. The high charge-carrier mobilities of the hexyl and octyl-substituted P34AT produce power conversion efficiencies of 4.2% in polymer:fullerene bulk heterojunction photovoltaic devices. An enhanced open-circuit voltage (0.716-0.771 eV) in P34AT solar cells relative to P3HT due to increased ionization potentials was observed.

Solid Oxygen-Purifying (SOP) Filters: A Self-Disinfecting Filters to Inactivate Aerosolized Viruses.

Normal heating, ventilation, and air conditioning (HVAC) systems typically use high-efficiency particulate air (HEPA) filters, which can filter dust, various pollutants, and even bacteria and viruses from indoor air. However, since HEPA filters cannot not clean themselves and due to the nature of these microbes which can survive for long periods of time, changing these filters improperly could transmit pathogenic bacteria or viruses, and could even lead to new infections. This study indicated that these manufactured Solid Oxygen-purifying (SOP) filters have the potential to self-disinfect, filter, and inactivate aerosolized viruses. MS2 bacteriophage was used as a model virus in two different experiments. The first experiment involved aerosolization of the virus, while the second were a higher viral load using a soaking method. The SOP filters inactivated up to 99.8% of the virus particles in both experiments, provided that the density of the SOP filter was high. Thus, SOP filters could self-clean, which led to protection against airborne and aerosolized viruses by inactivating them on contact. Furthermore, SOP filters could be potentially use or addition in HVAC systems and face masks to prevent the transmission of airborne and aerosolized viruses.

Biochip Performances of Agarose, Poly(Oligo(Ethylene Glycol) Methacrylate), and Poly(2-Hydroxyethyl Methacrylate) Film on Glass Surfaces.

We demonstrate the biochip efficacies of three different polymer films (agarose, poly(oligo(ethylene glycol) methacrylate) (pOEGMA), and poly(2-hydroxyethyl metacharylate) (pHEMA) on microscopic glass surfaces. As a result, the non-biofouling performances increased in this order: agarose < pOEGMA < pHEMA, and the binding capabilities increased in this order: pHEMA < pOEGMA < agarose.

A Novel Photocatalyst Composite of Magnesium Aminoclay and TiO2 Immobilized into Activated Carbon Fiber (ACF) Matrix for Pollutant Removal.

Titanium dioxide (TiO2) is a semiconductor photocatalyst widely applied in numerous fields due to possessing prominent photocatalytic properties. However, its practical applications in the form of nanoparticles or powders still have remained several limitations. Recently, novel photocatalytic porous composites have been discovered to be potential alternative approaches. In the present study, nanostructured magnesium-aminoclay-based TiO2 (MgAC-TiO2) was successfully deposited on an activated carbon fiber (ACF) matrix using the sol-gel approach followed by calcination at 350°C in an air atmosphere. The structure and photocatalytic activity of this as-prepared photocatalyst composite were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), the Brunauer-Emmett-Teller (BET), and UV-vis diffuse reflectance spectral analysis. The photocatalytic activity of MgAC-TiO2/ACF was investigated under batch conditions for the removal of methylene blue (MB) in solution under UV irradiation and dark conditions. The results revealed that MB is absorbed by MgAC-TiO2/ACF and that its photodecomposition occurs under UV irradiation. The addition of MgAC can prevent the sintering of TiO2 act as a dispersing agent to create a high specific surface area, and thus enhance photocatalytic efficiency. In addition, ACF in the MgAC-TiO2/ACF composite can additionally improve the photocatalytic activity by hindering electron-hole recombination, which is known as a synergetic effect, and thereby enhancing the photodegradation and removal efficiency of MB.

Synthesis of BaMgAl10O17:Eu2+ blue phosphor by electro-spray aerosol flame deposition.

Spherical and nano-sized BaMgAl10O17:Eu2+ (BAM) phosphor particles for plasma display panel (PDP) application were synthesized by Aerosol Flame Deposition (AFD) and subsequent heat treatment at 1250 degrees C for 4 h under reducing atmosphere. The effects of various atomization methods, precursor solution and various deposition position along flame axis were investigated in order to control the morphology and size of the phosphor. Characteristics of BAM phosphor were investigated for products prepared under various condition and they were compared with those of the commercial BAM. It was found that electro-spray gas-assisted atomization produce the most fine particle, while the optimum particle size for real application in phosphor devices (200-400 nm) was produced by the gas-blast atomizer.

Reduction of Escherichia Coli Using Metal Plates with the Influenced of Applied Low Current and Physical Barrier of Filter Layers.

Although metal contact is known to reduce bacterial growth, the effects of physical barriers and electricity need further investigation. This study examined the bacteria-reducing properties of copper and stainless-steel metal plates with an added electrical current and up to three filter layers on the growth of Escherichia coli (bacteria) and MS2 bacteriophages (virus). When used with a stainless-steel plate, electricity increased bacteria reduction by 39.5 ± 2.30% in comparison with no electricity added, whereas a three-layer physical barrier decreased its efficiency. Copper also reduced the growth of bacteria, by 58.2 ± 8.23%, and the addition of electricity reduced it further (79.5 ± 2.34%). Bacteriophages were also affected by the metal contact. Further experiments showed that MS2 was also reduced by copper, to 82.9 ± 4.5% after 24 h at 37 °C.

Emission Characteristics of Particulate Matter, Volatile Organic Compounds, and Trace Elements from the Combustion of Coals in Mongolia.

This study characterized emissions of particulate matter (PM), volatile organic compounds (VOCs), heavy metals, and anions from Mongolian bituminous coals in a controlled heating experiment. Three coal samples from Alag Tolgoi (coal 1), Baganuur (coal 2), and Nalaikh (coal 3) were combusted at a constant heat flux of 50 kW/m² using a dual-cone calorimeter. The coal samples were commonly used in ger district of Ulaanbaatar, Mongolia. PM10 emission factors were 1122.9 ± 526.2, 958.1 ± 584.0, and 472.0 ± 57.1 mg/kg for coal samples 1, 2, and 3, respectively. PM with a diameter of 0.35⁻0.45 µm was dominant and accounted for 41, 34, and 48% of the total PM for coal samples 1, 2, and 3, respectively. The emissions of PM and VOC from coals commonly used in Ulaanbaatar, Mongolia were significant enough to cause extremely high levels of indoor and outdoor air pollution.

Multipurpose Antifouling Coating of Solid Surfaces with the Marine-Derived Polymer Fucoidan.

The control of biofouling, which is the unwanted adsorption of biomolecules and organisms on solid surfaces, is a prerequisite for wider applicability of the functional materials that are currently being used in biomedical industries. One of the frequently used methods for controlling biofouling is the use of surface coatings with antifouling materials. Herein, fucoidan, which is a marine-derived polysaccharide, is reported as a new type of antifouling material that is safe and broadly applicable. Fucoidan is conjugated with catechols, which are known to act as adhesives for grafting functional molecules onto solid substrates. Fucoidan catechol (FD-C) is subsequently utilized for robust fucoidan coatings of solid substrates, and the FD-C-coated surfaces show excellent antifouling capability for fouling organisms, including platelets and bacteria. The FD-C coating is also confirmed to be nonirritating upon skin contact, demonstrating its potential use in public places for inhibiting contagions.

Direct patterning and biofunctionalization of a large-area pristine graphene sheet.

Direct patterning of streptavidin and NIH 3T3 fibroblast cells was successfully achieved over a large-area pristine graphene sheet on Si/SiO2 by aryl azide-based photografting with the conventional UV lithographic technique and surface-initiated, atom transfer radical polymerization of oligo(ethylene glycol) methacrylate.

Ru-catalyzed hydroamidation of alkenes and cooperative aminocarboxylation procedure with chelating formamide.

[reaction: see text] A strategy of chelation-assisted activation of formamide was employed to achieve hydroamidation of alkenes to generate one-carbon-elongated amides in moderate to good selectivity and yields. Also reported is the two-metal-catalyzed cooperative aminocarboxylation of aryl iodides, in which Ru is presumed to catalyze decarbonylation of formamide to release carbon monoxide and amine for the subsequent Pd-catalyzed aminocarboxylation routes, thus enabling the net transformation to be performed in the absence of external CO pressure.

Binding behaviors of protein on spatially controlled poly[oligo(ethylene glycol) methacrylate] brushes grafted from mixed self-assembled monolayers on gold.

Binding behaviors of streptavidin were investigated with different lateral packing densities of biotin-functionalized, non-biofouling pOEGMA brushes, synthesized by surface-initiated polymerization from mixed SAMs with different mole fractions of the polymerization initiator on gold surfaces.

A novel chelation-assisted hydroesterification of alkenes via ruthenium catalysis.

An efficient and catalytic protocol of hydroesterification of alkenes has been developed without a need for CO atmosphere. With the introduction of the 2-pyridyl moiety as a chelating group in formate, Ru3(CO)12-catalyzed activation of the formyl C-H bond of formate and subsequent addition of the intermediate to alkenes proceeded with almost complete suppression of decarbonylation. Stereoselectivity of the produced one-carbon elongated esters was good to excellent for the formation of the linear adduct depending on the bulkiness of the alkenes used. This procedure could be readily applied to a variety of olefins such as terminal, internal, cyclic, bicyclic, vinyl ether, and conjugated enone systems with high efficiency and selectivity. It was also amenable to a solvent-free condition. On the basis of the chelation-driven C-H bond activation of formate, a putative mechanism of the Ru-catalyzed hydroesterification of 2-pyridylmethyl formate has been proposed.

Ruthenium-catalyzed Heck-type olefination and Suzuki coupling reactions: studies on the nature of catalytic species.

Ruthenium-catalyzed Heck olefination and Suzuki cross coupling reactions have been developed. When starting with a ruthenium complex [RuCl(2)(p-cymene)](2) as a homogeneous catalyst precursor, induction periods were observed and ruthenium colloids of zero oxidation state were generated under catalytic conditions. Isolated ruthenium colloids carried out the olefination, implying that active catalytic species are ruthenium nanoclusters. To support this hypothesis, ruthenium nanoparticles stabilized with dodecylamine were independently prepared via a hydride reduction procedure, and their catalytic activity was subsequently examined. Olefination of iodobenzene with ethyl acrylate was efficiently catalyzed by the ruthenium nanoparticles under the same conditions, which could be also reused for the next runs. In poisoning experiments, the conversion of the olefination was completely inhibited in the presence of mercury, thus supporting our assumption on the nature of catalytic species. No residual ruthenium was detected from the filtrate at the end of the reaction. On the basis of the postulation, a heterogeneous catalyst system of ruthenium supported on alumina was consequently developed for the Heck olefination and Suzuki cross coupling reactions for the first time. It turned out that substrate scope and selectivity were significantly improved with the external ligand-free catalyst even under milder reaction conditions when compared to results with the homogeneous precatalyst. It was also observed that the immobilized ruthenium catalyst was recovered and reused up to several runs with consistent efficiency. Especially in the Suzuki couplings, the reactions could be efficiently carried out with as low as 1 mol % of the supported catalyst over a wide range of substrates and were scaled up to a few grams without any practical problems, giving coupled products with high purity by a simple workup procedure.