Optimization of alkali fusion process for determination of I-129 in solidified radwastes by neutron activation.

This study determines the optimum temperature for the alkali fusion process used to effectively separate iodine from solidified radwaste attaining low-level I by neutron activation. The alkali fusion temperature was adjusted to 120, 200, and 400 °C to approach the optimum conditions associated with a good statistical distribution of the measured I data and high chemical recovery yield. Statistical analysis revealed that the optimum temperature of the alkali fusion process was 200 °C, displaying good central tendency and low variance of the measured I data, and the respective chemical recovery yields were higher than other temperatures.

Highly efficient drug delivery systems based on functional supramolecular polymers: In vitro evaluation.

Unlabelled: The novel concept of modifying and enhancing the properties of existing functional micelles through self-complementary interactions has significant potential. In this study, a practical approach to living polymerization of functionalized thermoresponsive monomers enabled the incorporation of self-constituted multiple hydrogen bonded groups into micelles that have potential as supramolecular drug-delivery systems. Phase transitions and morphological studies in aqueous solution showed that the microstructure can be controlled to achieve well-defined vesicle-like micelles with respect to the strength of the hydrogen bond segment.

Functionalized graphene nanomaterials: new insight into direct exfoliation of graphite with supramolecular polymers.

A novel urea-cytosine end-capped polypropylene glycol (UrCy-PPG) can self-assemble into a long-range ordered lamellar microstructure on the surface of graphene, due to the strong specific interactions between UrCy-PPG and graphene. In addition, the graphene composite produced exhibits a high conductivity (∼1093 S m(-1)) with a dramatic thermo-responsive ON/OFF resistance-switching behavior (10 consecutive cycles).

Supramolecular Assembly Mediates the Formation of Single-Chain Polymeric Nanoparticles.

A breakthrough innovation in water-based polymeric nanoparticles has enabled significant progress in mimicking the folding of natural proteins by generating novel "single-chain polymeric nanoparticles" (SCPNs) via supramolecular interactions. In this study, a practical approach to the living polymerization of functionalized oligo(ethylene glycol) methacrylate monomers allows the incorporation of self-constituted multiple hydrogen-bonded groups into physically cross-linked polymer networks, which enables the formation of highly functionalized SCPNs in an aqueous environment. The newly developed materials are particularly attractive from a practical point of view since they have a very low critical micellization concentration and uniform particle diameters of ca.

Supramolecular assembly-induced enhanced emission of electrospun nanofibers.

A nucleobase-assembled supramolecular nanofiber is capable of forming network-like polymeric clusters through complementary hydrogen-bonding interactions. It behaves as an effective chromophore that greatly enhances the light emission efficiency of fluorescent fibers, reaching up to three times higher efficiency than the control samples.

Label-free DNA detection using two-dimensional periodic relief grating as a visualized platform for diagnosis of breast cancer recurrence after surgery.

In this study we fabricated a nanopillar array of silicon oxide, involving very-large-scale integration (VLSI) and reactive ion etching (RIE), as two-dimensional periodic relief gratings (2DPRGs) on Si surfaces. Thiolated oligonucleotide was successively immobilized on the thiol functionalized surfaces of 2DPRGs by disulfide bond as an optical probe to detect a human genomic DNA (hgDNA584), related to breast cancer recurrence after surgery, from a biological specimen. The oligonucleotide-bound 2DPRG alone produces insignificant structure change, but upon hybridization with hgDNA584 leads to a dramatic change of the pillar scale due to hgDNA584 filling inside the 2DPRG layers.

Mercury wet deposition in the eastern United States: characteristics and scavenging ratios.

Wet deposition is an important atmospheric mercury (Hg) pathway between air and terrestrial ecosystems. It is measured at numerous locations in the United States (U. S.

Bioinspired assembly of functional block-copolymer nanotemplates.

A new concept on bioinspired assembly of functional diblock copolymers, capable of forming different microstructures through nucleobase-induced supramolecular interactions, has been explored. In this paper, a new series of uracil-functionalized poly(ε-caprolactone)-b-(4-vinylbenzyl uracil)s (PCL-b-PVBU) have been prepared which exhibit a high self-complementary ability in solution and solid states owing to the formation of uracil–uracil pairs by induced hierarchical self-assembly. The ordered morphologies of PCL-b-PVBU diblock copolymers changed from a lamellar, hexagonally packed cylinder to a sphere with respect to the content of the hydrogen bond segment.

Electrorheological operation of low-/high-permittivity core/shell SiO2/Au nanoparticle microspheres for display media.

In this study, we synthesized core/shell structures comprising monodisperse 3-μm SiO(2) microspheres and gold nanoparticles (AuNPs, ca. 6.7 nm) as the core and shell components, respectively.

Novel chemical route to prepare a new polymer blend gate dielectric for flexible low-voltage organic thin-film transistor.

An organic-organic blend thin film has been synthesized through the solution deposition of a triblock copolymer (Pluronic P123, EO20-PO70-EO20) and polystyrene (PS), which is called P123-PS for the blend film whose precursor solution was obtained with organic additives. In addition to having excellent insulating properties, these materials have satisfied other stringent requirements for an optimal flexible device: low-temperature fabrication, nontoxic, surface free of pinhole defect, compatibility with organic semiconductors, and mechanical flexibility. Atomic force microscope measurements revealed that the optimized P123-PS blend film was uniform, crack-free, and highly resistant to moisture absorption on polyimide (PI) substrate.

A new supramolecular hole injection/transport material on conducting polymer for application in light-emitting diodes.

A new DNA-mimetic π-conjugated polymer poly(triphenylamine-carbazole) (PTC-U) has been prepared which exhibits high thermal stability, non-corrosion, excellent hole injection and electron-blocking abilities in the solid state owing to the uracil induced physical cross-linking. In addition, a trilayer device with PTC-U as a hole injection/transport layer is approximately 1.6 times higher than that of the commercial product PEDOT:PSS-based devices.

Bioinspired Photo-Cross-Linked Nanofibers from Uracil-Functionalized Polymers.

In this study, we used electrospinning to fabricate nucleobase-functionalized and photo-cross-linkable poly[1-(4-vinylbenzyl uracil)] (PVBU) nanofibers. PVBU of high-molecular-weight ( > 250 550 g/mol) possessed a high thermal stability and sufficient chain entanglement to produce uniform fibers without forming beads. These uracil-functionalized nanofibers were further photo-cross-linked through exposure to UV light at a wavelength of 254 nm.

Surface modification of poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) by confined photo-catalytic oxidation.

In this study, the surface of π-conjugated polymer, poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV), was successfully modified with the sulfate anion (SO(4-)) groups by the confined photo-catalytic oxidation (CPO). After the surface modification, the water contact angle of MEH-PPV is changed from 95.5° to 82.

Using colloid lithography to fabricate silicon nanopillar arrays on silicon substrates.

In this study, we partially grafted geminal silanol groups in the protecting organic shells on the surfaces of gold nanoparticles (AuNPs) and then assembled the alkyl-AuNP-Si(OH)(4) particles onto the surfaces of silicon (Si) wafers. The density of assembled AuNPs on the Si surface was adjusted by varying the geminal silanol group content on the AuNP surface; at its optimal content, it approached the high assembly density (0.0254 particles/nm(2)) of an AuNP assembled monolayer.

Versatile grafting approaches to star-shaped POSS-containing hybrid polymers using RAFT polymerization and click chemistry.

An alkyne-bearing polyhedral oligomeric silsesquioxane (POSS) core was used to prepare POSS-containing polymer hybrids using 'grafting to' or 'grafting from' strategies in combination with reversible chain transfer and click chemistry.

On modulating the self-assembly behaviors of poly(styrene-b-4-vinylpyridine)/octyl gallate blends in solution state via hydrogen bonding from different common solvents.

We have investigated the complexation-induced phase behavior of the mixtures of poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) and octyl gallate (OG) due to hydrogen bonding in different solvents. The Fourier transform infrared spectroscopic result indicates that the hydrogen-bonding was formed between the P4VP blocks and OG in both THF and DMF, implying the P4VP blocks can bind to OG. For PS-b-P4VP/OG mixture in chloroform, the morphological transitions were induced from the unimer configuration to swollen aggregate and complex-micelles by adding OG.

Self-supporting polymer from a POSS derivative.

A new polyhedral oligomeric silsesquioxane macromer, octakis[N-(6-aminopyridin-2-yl)undecanamide-10-dimethyl-siloxy]silsesquioxane (POSS-C11-Py), containing eight diaminopyridine arms, is able to self-assemble to form a physically crosslinked polymer-like structure with good mechanical properties (tensile strength = 46.1 MPa, tensile modulus = 0.58 GPa, elongation = 49.

Self-assembly behavior and photoluminescence property of bispyrenyl-POSS nanoparticle hybrid.

Two flexible ether bonds were designed to connect two pyrene rings on a polyhedral oligomeric silsesquioxane (BPy-POSS) to enrich the fraction of "intrinsic intramolecular pyrene-dimer" on the surface of crystal isobutyl-POSS (iBu-POSS) thin-films. Compared to the monomer emission of 1-pyrenemethanol (Py-OH), the emission spectra of BPy-POSS in dichloromethane show the large proportion of intramolecular and intermolecular excimers due to the formation of pyrenyl dimers or aggregates via the easy rotation of two adjacent ether bonds and the π-π interaction of pyrene rings, respectively. By blending inert iBu-POSS, the fluorescent dimers or aggregates of 5 wt.

Occurrence and fate of the herbicide glyphosate and its degradate aminomethylphosphonic acid in the atmosphere.

This is the first report on the ambient levels of glyphosate, the most widely used herbicide in the United States, and its major degradation product, aminomethylphosphonic acid (AMPA), in air and rain. Concurrent, weekly integrated air particle and rain samples were collected during two growing seasons in agricultural areas in Mississippi and Iowa. Rain was also collected in Indiana in a preliminary phase of the study.

A new supramolecular sulfonated polyimide for use in proton exchange membranes for fuel cells.

Uracil-terminated telechelic sulfonated polyimides (SPI-U) were transformed into noncovalent network membranes through biocomplementary hydrogen bonding recognition in the presence of an adenine-based crosslinking agent. SPI-U membrane exhibited dramatically improved methanol permeability, oxidative stability, proton conductivity, and selectivity relative to those of the standard SPI.

Thin-film composite materials as a dielectric layer for flexible metal-insulator-metal capacitors.

A new organic-organic nanoscale composite thin-film (NCTF) dielectric has been synthesized by solution deposition of 1-bromoadamantane and triblock copolymer (Pluronic P123, BASF, EO20-PO70-EO20), in which the precursor solution has been achieved with organic additives. We have used a sol-gel process to make a metal-insulator-metal capacitor (MIM) comprising a nanoscale (10 nm-thick) thin-film on a flexible polyimide (PI) substrate at room temperature. Scanning electron microscope and atomic force microscope revealed that the deposited NCTFs were crack-free, uniform, highly resistant to moisture absorption, and well adhered on the Au-Cr/PI.

Patterned poly(2-hydroxyethyl methacrylate) brushes on silicon surfaces behave as "tentacles" to capture ferritin from aqueous solution.

We have used a very large scale integration process to generate well-defined patterns of polymerized 2-hydroxyethyl methacrylate (HEMA) on patterned Si(100) surfaces. An atom transfer radical polymerization initiator covalently bonded to the patterned surface was employed for the graft polymerization of HEMA to prepare the poly(2-hydroxyethyl methacrylate) (PHEMA) brushes. After immersing wafers presenting lines of these polymers in water and cyclohexane, we observed brush- and mushroom-like regions, respectively, for the PHEMA brushes, with various pattern resolutions.

Improved reliability from a plasma-assisted metal-insulator-metal capacitor comprising a high-k HfO2 film on a flexible polyimide substrate.

We have used a sol-gel spin-coating process to fabricate a new metal-insulator-metal (MIM) capacitor comprising a 10 nm-thick high-k thin dielectric HfO(2) film on a flexible polyimide (PI) substrate. The surface morphology of this HfO(2) film was investigated using atomic force microscopy and scanning electron microscopy, which confirmed that continuous and crack-free film growth had occurred on the film surface. After oxygen (O(2)) plasma pretreatment and subsequent annealing at 250 degrees C, the film on the PI substrate exhibited a low leakage current density of 3.

Resonance effect on self- and inter-association hydrogen bonding interaction of polymer blend.

A comparative study of three poly(methacrylamides) containing different N-substitutions was carried out in order to obtain a better understanding of the resonance effects on the inter-association and self-association hydrogen bonding interactions in polymer blends. DSC and solid-state NMR analyses are employed to study the relative miscibility of these three binary blends, indicating that the PNPAA/P4VP blend has a better miscibility than the PNMAA/P4VP and PNCHAA/P4VP blends, because the resonance characteristic of the aromatic ring in PNPAA enhances the inter-association hydrogen bonding with P4VP based on FTIR and solid-state NMR analyses.

The Self-Assembled Structure of the Diblock Copolymer PCL-b-P4VP Transforms Upon Competitive Interactions with Octaphenol Polyhedral Oligomeric Silsesquioxane.

This paper describes the miscibility and self-assembly, mediated by hydrogen-bonding interactions, of new block copolymer/nanoparticle blends. The morphologies adopted by the immiscible poly[(ε-caprolactone)-block-(4-vinyl pyridine)] (PCL-b-P4VP) diblock copolymer changes upon increasing the number of competitive hydrogen-bonding interactions after adding increasing amounts of octaphenol polyhedral oligomeric silsesquioxane (OP-POSS). Transmission electron microscopy reveals morphologies that exhibit high degrees of long-range order, such as cylindrical and spherical structures, at relatively low OP-POSS contents, and short-range order or disordered structures at higher OP-POSS contents.