Development of multianalyte sensor arrays composed of chemically derivatized polymeric microspheres localized in micromachined cavities.

The development of a chip-based sensor array composed of individually addressable polystyrene-poly(ethylene glycol) and agarose microspheres has been demonstrated. The microspheres are selectively arranged in micromachined cavities localized on silicon wafers. These cavities are created with an anisotropic etch and serve as miniaturized reaction vessels and analysis chambers. A single drop of fluid provides sufficient analysis media to complete approximately 100 assays in these microetch pits. The cavities possess pyramidal pit shapes with trans-wafer openings that allows for both fluid flow through the microreactors/analysis chambers and optical access to the chemically sensitive microspheres. Identification and quantitation of analytes occurs via colorimetric and fluorescence changes to receptor and indicator molecules that are covalently attached to termination sites on the polymeric microspheres. Spectral data are extracted from the array efficiently using a charge-coupled device allowing for the near-real-time digital analysis of complex fluids. The power and utility of this new microbead array detection methodology is demonstrated here for the analysis of complex fluids containing a variety of important classes of analytes including acids, bases, metal cations, metabolic cofactors, and antibody reagents.     

Electronic and steric effects controlling efficiencies of photoaddition reactions of fullerene C60 with N-α-trimethylsilyl-N-alkyl-N-benzylamines

Single electron transfer (SET)-promoted photoaddition reactions between fullerene C₆₀ and both various alkyl (Me, Et, i-Pr, t-Bu)- and para-substituted (p-Me, p-OMe, p-F, p-CF₃) arene ring containing, N-α-trimethylsilyl-N-alkyl-N-benzylamines were explored to gain information about photoproduct profiles and how the electronic and steric nature of the amine substrates influence reaction efficiencies. The results show that visible light (λ > 540 nm) irradiation of 10% EtOH-toluene solutions containing C₆₀ and N-α-trimethylsilyl-N-alkyl-N-benzylamines produce 1-aminomethyl-1,2-dihydrofullerenes as a sole photoproduct. In addition, SET-promoted photoaddition reactions of unsubstituted and para-electron donating group substituted arene ring containing N-α-trimethylsilyl-N-alkyl-N-benzylamines take place to give photoproducts more efficiently than those containing para-electron withdrawing group substituted arene rings. Moreover, although steric factors are less significant than the electronic nature of the amine substrates in governing reaction efficiencies, sterics do play a significant role in photoreactions of electron deficient amine substrates.     

An unsplit staggered mesh scheme for multidimensional magnetohydrodynamics

We introduce an unsplit staggered mesh scheme (USM) for multidimensional magnetohydrodynamics (MHD) that uses a constrained transport (CT) method with high-order Godunov fluxes and incorporates a new data reconstruction–evolution algorithm for second-order MHD interface states. In this new algorithm, the USM scheme includes so-called “multidimensional MHD terms”, proportional to $?·\mathbf{B}$, in a dimensionally-unsplit way in a single update. This data reconstruction–evolution step, extended from the corner transport upwind (CTU) approach of Colella, maintains in-plane dynamics very well, as shown by the advection of a very weak magnetic field loop in 2D. This data reconstruction–evolution algorithm is also of advantage in its consistency and simplicity when extended to 3D. The scheme maintains the $?·\mathbf{B}=0$ constraint by solving a set of discrete induction equations using the standard CT approach, where the accuracy of the computed electric field directly influences the quality of the magnetic field solution. We address the lack of proper dissipative behavior in the simple electric field averaging scheme and present a new modified electric field construction (MEC) that includes multidimensional derivative information and enhances solution accuracy. A series of comparison studies demonstrates the excellent performance of the full USM–MEC scheme for many stringent multidimensional MHD test problems chosen from the literature. The scheme is implemented and currently freely available in the University of Chicago ASC FLASH Center’s FLASH3 release.     

Preparation and electrochemical performance of titanium nitride-graphene nanocomposite with high Ti contents and tailored morphology

Titanium nitride (TiN) - graphene (G) nanocomposites are promising for electrochemical charge storage where a high content of Ti species is desired. Herein, we propose an effective method for the preparation of TiN-G nanocomposites with a high concentration of Ti species. These nanocomposites can be successfully achieved through a further deposition of Ti on Ti-graphene oxide (GO) or a thermally exfoliated Ti-GO. Depending on the annealing condition employed (NH₃ and N₂), two types of TiN-G nanocomposites (NH₃ annealing for TiN/G and TiN/G-TE, TE: thermal exfoliation) and a TiO₂-G nanocomposite (N₂ annealing for TiO₂/G-TE) were prepared. These nanocomposites were then investigated for potential application as an electrochemical supercapacitor. Compare with TiO₂/G-TE, the TiN-G nanocomposites both exhibited a higher specific capacitance, although one of these nanocomposites had a lower surface area than TiO₂/G-TE. Among the nanocomposites prepared, TiN/G-TE delivered the best electrochemical performance. The relationship between the physical properties and the capacitive performance of the nanocomposites were systematically evaluated.     

Impact and high strain rate delamination characteristics of carbon fibre epoxy composites

Delamination mechanisms and energy dissipation of carbon fibre epoxy composites under impact and high strain rate conditions are studies in terms of a new experimental set-up. The test set-up is designed to separate the Mode-I, -II and mixed mode delamination resistance so that relevant mechanisms can be studied in greater detail. The impact specimens consist of 18 × 18 mm laminated composite pieces bonded to steel bars to form the impact specimens with the normal Charpy and Izod specimen geometry. The impact energy dissipation is recorded and taken as a dynamic delamination toughness measurement, and the transition from the pure Mode-I to Mode-II through the mixed mode delamination is measured. Detailed delamination surface examinations by scanning electron microscopy (SEM) show that different failure mechanisms are involved in the dynamic and usual quasi-static delamination processes. The influence of chopped Kevlar fibres used as low cost interlaminar reinforcement on the energy dissipation is also studied.     

Dispersion of Pt-Ru alloys onto various carbons using γ-irradiation

(PVP)-protected Pt-Ru alloy nanoparticles were prepared using γ-irradiation at room temperature. Pt-Ru alloy particles were successfully dispersed onto various carbon structures, including Vulcan XC-71, Ketjen-300, Ketjen-600, single-walled carbon nanotubes (SWCNTs), and multi-walled carbon nanotubes (MWCNTs) to form new types of Pt-Ru/carbon-based composites. While Pt-Ru alloy nanoparticles were mainly aggregated on Vulcan XC-71, Ketjen-300 and Ketjen-600, SWCNTs and MWCNTs provided hydrophilic sites for improving the distribution of alloy particles. FT-IR spectroscopy provided evidence for the formation of carboxylate and hydroxyl groups on the surface of the nanotubes after γ-irradiation. These functional groups serve as the nuclei that resulted in the improved dispersion of alloy nanoparticles onto SWCNTs and MWCNTs.     

Phase-field Determination of NaSICON Materials in the Quaternary System Na2O−P2O5−SiO2−ZrO2: The Series Na3Zr3–xSi2PxO11.5+x/2

Two types of solid electrolytes have reached technological relevance in the field of sodium batteries: ß/ß”-aluminas and NaSICON-type materials. Today, significant attention is paid to room-temperature stationary electricity storage technologies and all-solid-state Na batteries used in combination with these solid electrolytes are an emerging research field besides sodium-ion batteries. In comparison, NaSICON materials can be processed at lower sintering temperatures than the ß/ß”-aluminas and have a similarly attractive ionic conductivity. Since Na₂O−SiO₂−ZrO₂−P₂O₅ ceramics offer wider compositional variability, the series Na₃Zr_3–xSi₂P_xO_11.5+x/2 with seven compositions (0≤x≤3) was selected from the quasi-quaternary phase diagram in order to identify the predominant stability region of NaSICON within this series and to explore the full potential of such materials, including the original NaSICON composition of Na₃Zr₂Si₂PO_l2 as a reference. Several characterization techniques were used for the purpose of better understanding the relationships between processing and properties of the ceramics. X-ray diffraction analysis revealed that the phase region of NaSICON materials is larger than expected. Moreover, new ceramic NaSICON materials were discovered in the system crystallizing with a monoclinic NaSICON structure (space group C2/c). Impedance spectroscopy was utilized to investigate the ionic conductivity, giving clear evidence for a dependence on crystal symmetry. The monoclinic NaSICON structure showed the highest ionic conductivity with an optimum ionic conductivity of 1.22×10⁻³ at 25 °C for the composition Na₃Zr₂Si₂PO₁₂. As the degree of P⁵⁺ content increases, the total ionic conductivity is initially enhanced until x=1 and then decreases again. Simultaneously, the increasing amount of phosphorus leads a decrease in the sintering temperatures for all samples, which was confirmed by dilatometry measurements. The thermal and microstructural properties of the prepared samples are also evaluated and discussed.     

Solid state of a new COX-2 inhibitor CG100649

CG100649 [4-(3-(3-Fluorophenyl)-5,5-dimethyl-4-oxo-4,5-dihydrofuran-2-yl)-benzenesulfonamide, polmacoxib, Acelex™] is a new NSAID used to treat osteoarthritis. It inhibits the enzymes carbonic anhydrase and COX-2. The objective of this work was to investigate the existence of polymorphs of CG100649 and the solubility of different crystal forms of CG100649. Four crystal forms of CG100649 (Forms 1–4) have been isolated by recrystallization and characterized by differential scanning calorimetry and powder X-ray diffractometry. In dissolution studies in pH 6.8 ± 0.05 buffer at 37 ± 0.5 °C, the solubility of Form 1 was the highest, and the dissolution rate at 30 min in water decreased in rank order: Form 3 > Form 2 > Form 4. After storage for one month at 2 °C and 24% relative humidity, all crystal forms were not transformed.

     

Cryopreservation of dormant herbaceous peony (Paeonia lactiflora pall.) shoot-tips by desiccation

A simplified technique for the cryoprotection of dormant shoot-tips was developed for the germplasm conservation of herbaceous peony (Paeonia lactiflora Pall.). The highest post-thaw regrowth level was obtained from shoot-tips desiccated by air drying for 5 h. The post-thaw regrowth of P. lactiflora. var. 'Mikang' was the highest (74.9 percent) among the five genotypes tested. The regeneration level after cryopreservation was highest (66approximate74%; average of 70 percent) for dormant shoot-tips collected from November to February. Shoot tips which were dissected from non-dormant buds in late March, however, showed very low post-thaw regrowth. Post-thaw regrowth of shoot-tips was promoted in MS medium containing 1 mg 1(-1) of gibberellic acid (GA3) and 0.5 mg 1(-1) of N(6)-benzyladenine (BA). The elongated shoots were rooted on a 1/4 MS medium containing 0.1 mg 1(-1) of beta-naphthalene acetic acid (NAA). In addition, random amplified polymorphic DNAs (RAPDs) assays suggested that the cryostorage treatment used here preserved the genetic fidelity of the peony dormant shoot-tips. This cryopreservation method appears to be promising for the conservation of herbaceous peony germplasm.     

Detection of nitroaromatic explosives based on photoluminescent polymers containing metalloles

The synthesis, spectroscopic characterization, and fluorescence quenching efficiency of polymers and copolymers containing tetraphenylsilole or tetraphenylgermole with Si-Si, Ge-Ge, and Si-Ge backbones are reported. Poly(tetraphenyl)germole, 2, was synthesized from the reduction of dichloro(tetraphenyl)germole with 2 equivs of Li. Silole-germole alternating copolymer 3 was synthesized by coupling dilithium salts of tetraphenylsilole dianion with dichloro(tetraphenyl)germole. Other tetraphenylmetallole-silane copolymers, 4-12, were synthesized through the Wurtz-type coupling of the dilithium salts of the tetraphenylmetallole dianion and corresponding dichloro(dialkyl)silanes. The molecular weights (M(w)) of these metallole-silane copolymers are in the range of 4000 approximately 6000. Detection of nitroaromatic molecules, such as nitrobenzene (NB), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), and picric acid (PA), has been explored. A linear Stern-Volmer relationship was observed for the first three analytes, but not for picric acid. Fluorescence spectra of polymetalloles or metallole-silane copolymers obtained in either toluene solutions or thin polymer films displayed no shift in the maximum of the emission wavelength. This suggests that the polymetalloles or metallole-silanes exhibit neither pi-stacking of polymer chains nor excimer formation. Fluorescence lifetimes of polymetalloles and metallole-silanes were measured both in the presence and absence of TNT, and tau(o)/tau is invariant. This requires that photoluminescence quenching occurs by a static mechanism.