Physical fault tolerance of nanoelectronics

The error rate in complementary transistor circuits is suppressed exponentially in electron number, arising from an intrinsic physical implementation of fault-tolerant error correction. Contrariwise, explicit assembly of gates into the most efficient known fault-tolerant architecture is characterized by a subexponential suppression of error rate with electron number, and incurs significant overhead in wiring and complexity. We conclude that it is more efficient to prevent logical errors with physical fault tolerance than to correct logical errors with fault-tolerant architecture.     

Microwave‐Assisted One‐Pot Synthesis of Substituted 3‐Bromoimidazo[1,2‐a]pyridines and Imidazoheterocycles

Herein, an efficient, one‐pot microwave‐assisted synthesis of a diverse set of 3‐bromoimidazo[1,2‐a]pyridines is being reported with good yields (40–85%). The method involves electrophilic aromatic bromination using bromodimethylsulfonium ion generated in situ via oxidation of HBr salt by DMSO. This methodology was also applied to the synthesis of related imidazoheterocycles. Copyright © 2014 HeteroCorporation     

Engineering Non‐sintered,Metal‐Terminated Tungsten Carbide Nanoparticles for Catalysis

Transition‐metal carbides (TMCs) exhibit catalytic activities similar to platinum group metals (PGMs), yet TMCs are orders of magnitude more abundant and less expensive. However, current TMC synthesis methods lead to sintering, support degradation, and surface impurity deposition, ultimately precluding their wide‐scale use as catalysts. A method is presented for the production of metal‐terminated TMC nanoparticles in the 1–4 nm range with tunable size, composition, and crystal phase. Carbon‐supported tungsten carbide (WC) and molybdenum tungsten carbide (Mo_xW_1?xC) nanoparticles are highly active and stable electrocatalysts. Specifically, activities and capacitances about 100‐fold higher than commercial WC and within an order of magnitude of platinum‐based catalysts are achieved for the hydrogen evolution and methanol electrooxidation reactions. This method opens an attractive avenue to replace PGMs in high energy density applications such as fuel cells and electrolyzers.     

Synthesis, characterization, and electrocatalytic activity of PtPb nanoparticles prepared by two synthetic approaches

Intermetallic PtPb nanoparticles have been synthesized by two solution-phase reduction methods. In the first (PtPb-B), Pt and Pb salts were reduced by sodium borohydride in methanol at room temperature. In the second (PtPb-N), metal-organic Pt and Pb precursors were reduced by sodium naphthalide in diglyme at 135 degrees C. Both methods produced small agglomerated nanoparticles of the ordered intermetallic PtPb (mean crystal domain size <15 nm) which were characterized by pXRD, SEM, UHV-STEM, BET, EDX, and electron diffraction. The electrocatalytic activity of PtPb nanoparticles produced by both methods toward formic acid and methanol oxidation was investigated and compared to Pt and PtRu. Both PtPb-B and PtPb-N nanoparticles exhibited enhanced electrocatalytic activity compared to commercially available Pt black and PtRu nanoparticles. For formic acid oxidation, the PtPb nanoparticles exhibited considerably lower onset potentials and higher current densities than Pt or PtRu. For methanol oxidation, the PtPb nanoparticles had onset potentials slightly positive of PtRu but exhibited higher current densities at potentials about 100 mV positive of onset. The general applicability of these methods for the synthesis of nanoparticles of ordered intermetallic phases is discussed.     

Rapid self-assembly of core-shell organosilicon microcapsules within a microfluidic device

The preparation of hierarchically structured organosilicon microcapsules from commercially available starting materials is described. Using a microfluidic device, an emulsion of dichlorodiphenylsilane is formed in a continuous phase of aqueous glycerol. The silane droplets undergo hydrolysis, condensation, and crystallization within minutes to form self-assembled, core-shell microcapsules. The microparticles have been characterized with light and electron microscopy, nuclear magnetic resonance spectroscopy (NMR), diffusion-ordered NMR spectroscopy (DOSY), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and powder X-ray diffraction (XRD). The characterization data show that the microcapsule walls consist of amorphous, oligomeric poly(diphenylsiloxane) surrounded by a spiny layer of crystalline diphenylsilanediol. Glycerol is occluded within the wall material but is not covalently bound to the silicon components. Glycerol is a crucial element for producing low-dispersity microcapsules with well-ordered surface spines, as the use of methyl cellulose as viscomodifier yields amorphous surfaces.