Chemically immobilised carbon nanotubes on silicon: Stable surfaces for aqueous electrochemistry

Diazonium ion chemistry has been used to electrochemically graft aminophenyl layers onto p-type silicon (1 0 0) substrates. A condensation reaction was used to immobilise single-walled carbon nanotubes with high carboxylic acid functionality directly to this layer. Electrochemical monitoring of the aminophenyl groups confirmed the formation of an amide linkage between the single-walled carbon nanotubes and the aminophenyl layer. The carbon nanotube electrode showed high stability and good electrochemical performance in aqueous solution. At moderate scan rates the Ru(NH₃)₆^+3/+2 couple exhibited quasi-reversible electron transfer kinetics with a standard heterogenous rate constant of 1.2 × 10⁻³ cm s⁻¹ at the covalently-linked carbon nanotube surface. The electrode thus combines the advantages of a silicon substrate for easy integration into sophisticated electrical and electronic devices, carbon nanotubes for desirable electrochemical properties, and stability in aqueous medium for future applications in environmental sensing.     

Lead silicate glass structure: New insights from diffraction and modeling of probable lone pair locations

Structures of binary PbO-SiO₂ glasses have been studied in detail over the compositional range 35 to 80 mol% PbO using high-resolution neutron diffraction, high-energy X-ray diffraction, static ²⁰⁷Pb NMR, and structural modeling. The changes in the local environment of Pb(II) are subtle; it has a low coordination to oxygen (∼3 to 4) plus a stereochemically active electron lone pair and, thus, behaves as a glass network forming (or intermediate) cation over the entire composition range. This conclusion contradicts previous reports that Pb(II) is a network modifier at low concentrations, and is supported by an analysis of lead and alkaline earth silicate glass molar volumes. The Pb-O peak bond length shortens by 0.04 Å with increasing PbO content, indicating stronger, more covalent bonding, and consistent with an increase in the number of short (≤ 2.70 Å) Pb-O bonds, from 3.3 to 3.6. This is accompanied by increased axial symmetry of the Pb(II) sites, and is interpreted as a gradual transition toward square pyramidal [PbO₄] sites such as those found in crystalline PbO polymorphs. An attendant decrease in the periodicity associated with the first sharp diffraction peak (FSDP) toward that of β-PbO, accompanied by increases in the correlation lengths associated with the plumbite network (FSDP) and silicate anions (neutron prepeak), provides evidence of increased intermediate-range order and has implications for the glass forming limit imposed by crystallization. Pb(II) electron lone pairs occupy the natural voids within the silicate network at low PbO contents, while at high PbO contents they aggregate to create voids that form part of the plumbite network, analogous to the open channels in Pb₁₁Si₃O₁₇ and the layered structures of α- and β-PbO. Si-O and Pb-O bond lengths have been correlated with ²⁹Si and ²⁰⁷Pb NMR chemical shifts, respectively. This is the first time that such correlations have been demonstrated for glasses and attests to the accuracy with which pulsed neutron total scattering can measure average bond lengths.     

Deep learning for part identification based on inherent features

The identification of parts is essential for the efficient automation of logistic processes such as part supply in assembly and disassembly. This paper describes a new method for the optical identification of parts without explicit codes but based on inherent geometrical features with Deep Learning. The paper focusses on the improvement of training of Deep Learning systems taking into account conflicting factors such as limited training data and high variety of parts. Based on a case study in turbine industry the effects of steadily growing training data on the robustness of part classification are evaluated.     

Tragverhalten und Bemessung von Befestigungen mit Verbunddübeln unter Zugbeanspruchung ‐ Teil 1

Behaviour and Design of Adhesive Anchors under Tensile Loading In engineering construction anchors are increasingly used to transfer loads to hardened concrete. Anchor systems using chemical mortars (bonded anchors) are often used. In this article the behaviour and design of fastenings with bonded anchors is discussed. The design model is based on the CCMethod [1] and considers the main influencing parameters on the failure load of bonded anchors with adequate accuracy.