Silver-Copper Alloy Nanoinks for Ambient Temperature Sintering.

There is an increasing need to reduce the silver content in silver-based inks or pastes and achieve low-temperature sintering for scalable and low-cost production of printed wearable electronics. This need depends on the ability to control the metal composition and the surface properties of the nanoinks. Alloying silver with copper provides a pathway for meeting the need in terms of cost reduction, but little is known about the composition controllability and the low-temperature sintering capability. We report herein a scalable wet chemical synthesis of bimetallic silver-copper alloy nanoinks with room temperature sintering properties. The bimetallic alloy nanoparticles with a controllable composition can be formulated as stable nanoinks. The nanoinks printed on paper substrates are shown to sinter under room temperature. In addition to composition dependence, the results reveal an intriguing dependence of sintering on humidity above the printed nanoink films. These findings are assessed based on theoretical simulation of the sintering processes via surface-mediated sintering and interparticle necking mechanisms in terms of nanoscale adsorption, adhesion and diffusion, and surface free energies. Implications of the findings for room temperature fabrication of wearable sensors are also discussed.

Playing Favorites: Preferential Adsorption of Nonionic over Anionic Surfactants at the Liquid/Liquid Interface.

While many studies have investigated synergic interactions between surfactants in mixed systems, understanding possible competitive behaviors between interfacial components of binary surfactant systems is necessary for the optimized efficacy of applications dependent on surface properties. Such is the focus of these studies in which the surface behavior of a binary surfactant mixture containing nonionic (Span-80) and anionic (AOT) components adsorbing to the oil/water interface was investigated with vibrational sum-frequency (VSF) spectroscopy and surface tensiometry experimental methods. Time-dependent spectroscopic studies reveal that while both nonionic and anionic surfactants initially adsorb to the interface, anionic surfactants desorb over time as the nonionic surfactant continues to adsorb. Concentration studies that vary the ratio of Span-80 to AOT in bulk solution show that the nonionic surfactant preferentially adsorbs to the oil/water interface over the anionic surfactant. These studies have important implications for applications in which mixed surfactant systems are used to alter interfacial properties, such as pharmaceuticals, industrial films, and environmental remediation.

Development of draft validation criteria for a soluble biomarker to be regarded as a valid biomarker reflecting structural damage endpoints in rheumatoid arthritis and spondyloarthritis clinical trials.

OBJECTIVE: Recent work has shown that several soluble biomarkers, detectable in peripheral blood, synovial fluid, and/or urine, reflect remodeling of joint tissues and may therefore constitute outcome measures that reflect joint damage. Consequently, it is now desirable to begin the process of developing criteria for validation of a soluble biomarker as an outcome measure reflecting structural damage progression in trials of disease-modifying therapies for rheumatoid arthritis (RA) and spondyloarthritis (SpA). Our objective was to develop validation criteria for a soluble biomarker to be regarded as a valid biomarker reflecting radiological endpoints in RA and SpA clinical trials. METHODS: A special interest group was established comprising investigators with expertise in soluble biomarker assay development as well as in outcomes research. This project was initiated by means of a Delphi consensus exercise. A list of draft criteria was first generated following a review of a US National Institutes of Health (NIH) 2000 white paper (available at: http://www.niams.nih.gov/ne/oi/ oabiomarwhipap.htm) that focused on biomarkers in OA, and these were organized under subject headings relevant to the OMERACT filter: truth, discrimination, and feasibility. Additional criteria were solicited from the working group. This was followed by 3 rounds of voting. RESULTS: A list of 31 criteria was generated prior to voting. The first 2 rounds of voting resulted in cumulative agreement that 19 criteria be retained and 4 discarded, while discrepancies were recorded for 8 criteria. In the third round of voting, cumulative agreement was achieved to retain 5 of the 8 discrepant criteria, so that the final list included 24 criteria. CONCLUSION: A draft set of criteria for validation of a soluble biomarker to be regarded as reflecting radiological damage endpoints in clinical trials has been proposed on the basis of consensus.