On the number of types of finite dimensional Hopf algebras

For an odd prime p we construct an infinite class of non-isomorphic Hopf algebras of dimension p ⁴ over an infinite field containing primitive p-th roots of unity, answering in the negative a long standing conjecture of Kaplansky. Oblatum 6-XI-1997 / Published online: 12 November 1998     

The discovery of 3-(1-aminoethylidene)quinoline-2, 4(1H,3H)-dione derivatives as novel PSII electron transport inhibitors

Based on the structures of the 4-hydroxyphenylpyruvate dioxygenase inhibitor mesotrione and natural product fischerellin A, a series of imine derivatives of ( $E$ )-3-acyl-quinoline-2,4(1H,3H)-dione (6, 12 and 16) were designed, synthesized and systematically evaluated for their herbicidal activity. The bioassay results indicated that most of the synthesized compounds displayed good to excellent herbicidal activity, of which 6e, 6g, 6h, 6q and 6t exhibited more than 50 % inhibition against Brassica napus L., Amaranthus retroflexu or Digitaria adscendens at a dosage of $94\,\hbox {g}\,\hbox {ha}^{-1}$ or lower. The symptom of injured leaves in vivo, the high Hill reaction inhibitory activity of 6h in vitro ( $\hbox {IC}_{50}\,0.1\, \upmu \hbox {g}\,\hbox {mL}^{-1})$ and the computer-based binding model of compound 6h with D1 protein in photosystem II (PSII) reaction centre suggest this novel structure to likely be a new type of PSII electron transport inhibitor. Thus, we have found a novel type of diketone enamine structure targeted at the PSII reaction centre.     

Optimising reproducibility in low quality signals without smoothing; an alternative paradigm for signal processing

Raman spectroscopy has been revolutionised in recent decades by major technological advances such as lasers, charge‐coupled detectors (CCD) and notch/edge filters. In contrast the development of signal processing algorithms has progressed at a slower pace. Spectroscopic applications increasingly focus on ‘real‐world’ applications that are not under highly controlled conditions and with more stringent limitations placed on acquisition conditions (e.g. low power for in vivo and explosives analysis). Often it is necessary to work with signals of a quality traditionally considered poor. In this study an alternative paradigm for signal processing poor quality signals is presented and rigorously assessed. Instead of estimating the background on the individual signals it is estimated on the results of a multivariate analysis. Under this paradigm prediction reproducibility is unaffected by the signal processing, unlike the traditional paradigm of correcting individual signals which induces errors that propagate through to the prediction. The paradigms were tested on a ‘real‐world’ dataset to predict the concentration of a pathologically relevant protein modification, carboxymethyl lysine (CML). Use of the new paradigm allowed signals with a signal to noise ratio (SNR) of 2.4 to give a prediction with variance just 8.7% of the mean, with the traditional paradigm giving a variance of over 140% of the mean. Significant improvement in reproducibility could even be observed with signals as good as SNR 85. The ability to obtain reproducible predictions from low quality signals allows shorter acquisition (e.g. mapping or on‐line analysis), use of low powers (in vivo diagnostics, hazardous materials analysis (HAZMAT)) or use of cheaper equipment. Copyright © 2011 John Wiley & Sons, Ltd.     

Direct attachment of well-aligned single-walled carbon nanotube architectures to silicon (100) surfaces: a simple approach for device assembly

A new approach for the attachment of vertically-aligned shortened carbon nanotube architectures to a silicon (100) substrate by chemical anchoring directly to the surface has been demonstrated for the first time. The ordered assembly of single-walled carbon nanotubes (SWCNTs) was accomplished by hydroxylating the silicon surface followed by a condensation reaction with carboxylic acid functionalised SWCNTs. This new nanostructure has been characterised by X-ray photoelectron, Raman and Fourier transform infrared (FTIR) spectroscopy as well as scanning electron and atomic force microscopy. The assembly behaviour of SWCNTs onto the silicon surface shows a fast initial step producing isolated functionalised carbon nanotubes or nanotube bundles anchored to the silicon surface followed by a slower step where the adsorbed nanotubes grow into larger aggregates via van der Waals interactions between adsorbed and solvated nanotubes. The electrochemical and optical properties of the SWCNTs directly attached to silicon have also been investigated. These new nanostructures are excellent electrochemical electrodes. They also fluoresce in the wavelength range 650-800 nm. The successful attachment of the SWCNTs directly to silicon provides a simple, new avenue for fabrication and development of silicon-based nanoelectronic, nano-optoelectronic and sensing devices. Compared to existing techniques, this new approach has several advantages including low operating temperature, low cost and the possibility of further modification.     

Synthesis and surface structure of thymine-functionalized, self-assembled monolayer-protected gold nanoparticles

Thymine-functionalized SAM-protected gold nanoparticles with diameters of 2.2 +/- 0.3 nm and 7.0 +/- 1.0 nm were prepared via a modified two-phase transfer method. UV-vis spectra showed that particle size and solvent type, as well as surface charge, influenced the gold surface plasmon band absorption, along with the interaction between thymine terminal groups in the solution. Although the bulky thymine end groups interacted strongly on the particle surface, a well-ordered monolayer of thyminethiol derivatives with a long hydrocarbon chain was formed on the particle surface, exhibiting an ordered, all-trans conformation of the methylene backbone, similar to those of corresponding self-assembled monolayers (SAMs) generated from normal alkanethiols. A larger particle size and a longer reaction time facilitated the formation of more ordered thymine-terminated thiol SAMs. Thermal analysis indicated that reorientation of the SAMs during heat treatment occurred by two processes, caused possibly by the separate recrystallization of the hydrocarbon long chains and thymine units. More ordered SAMs with a higher thermal stability were formed on the larger particle surfaces when compared with those on the smaller ones. A greater density of molecular packing was found on the smaller particle surfaces. However, SAMs formed on the larger gold particles resembled 2D SAMs on the smooth, flat gold surfaces. XPS results confirmed the thymine structure as well as the chemical bond between gold and sulfur. One type of adsorbed sulfur species was observed for the smaller particles and two for the larger ones, but a slightly higher binding energy of thiolate was found for the smaller ones.     

The oscillographic polarography of noble metal complexes

The polarographic behaviour of complexes of the noble metals was studied by oscillographic polarography. A method was developed for the polarographic determination of copper, gold and palladium; silver and nickel do not interfere. Applications to the analysis of dental alloys proved successful.