Quality management education over the Internet

We describe a program for continuing education in Quality management and metrology. It may be followed by class lectures, by videoconference or by individual distance learning over the Internet. An important feature for students who attend classes is visits to selected institutions for demonstrations of quality management in practice. For students using distance learning, multimedia presentations containing a total of 2 h of video and supporting documentation is the alternative to the visits. The program is aimed at personnel from all fields, and its emphasis is on the generality of quality principles, attitudes and motivation for quality thinking, measurements in quality work, as well as the use of system audits and other elements of quality management in related fields.     

Synthesis,redox properties,and EPR spectroscopy of manganese(III) complexes of the ligand N,N-bis(2-hydroxybenzyl)-N'-2-hydroxybenzylidene-1,2-diaminoethane: formation of mononuclear,dinuclear, and even higher nuclearity complexes

The synthesis and characterization of the title trisphenolate ligand are described. From its reaction with manganese(III) three complexes were isolated. The crystal structures revealed one pentacoordinate monomer and two similar dimers with different solvents of crystallization. In the dimers the metal ions are hexacoordinate and connected through bridging of two phenolates. A combination of electrochemistry and EPR spectroscopy showed that, in acetonitrile, the isolated batches were all identical and mainly monomeric, indicating that the mononuclear complex is in equilibrium with the dimer and perhaps also with complexes of higher nuclearity, as suggested by the detection of both the trimer and the tetramer by electrospray ionization mass spectrometry (ESI-MS). The successful use of the monomer batch as an epoxidation catalyst indicated that a high-valent manganese-oxo species can be formed, although it is probably short-lived. This is also suggested by EPR studies of the species formed by electrochemical oxidation of the complex. Upon one-electron oxidation, a manganese(IV) species was formed, which was at least partly converted to another species containing a phenoxy radical.     

Circumferential-wave phase velocities for empty,fluid-immersed spherical metal shells

In earlier studies of acoustic scattering resonances and of the dispersive phase velocities of surface waves that generate them [see, e.g., Talmant et al., J. Acoust. Soc. Am. 86, 278-289 (1989) for spherical aluminum shells] we have demonstrated the effectiveness and accuracy of obtaining phase velocity dispersion curves from the known acoustic resonance frequencies. This possibility is offered through the condition of phase matching after each complete circumnavigation of these waves [Uberall et al., J. Acoust. Soc. Am. 61, 711-715 (1977)], which leads to a very close agreement of resonance results with those calculated from three-dimensional elasticity theory whenever the latter are available. The present investigation is based on the mentioned resonance frequency/elasticity theory connection, and we obtain comparative circumferential-wave dispersion-curve results for water-loaded, evacuated spherical metal shells of aluminum, stainless steel, and tungsten carbide. In particular, the characteristic upturn of the dispersion curves of low-order shell-borne circumferential waves (A or A0 waves) which takes place on spherical shells when the frequency tends towards very low values, is demonstrated here for all cases of the metals under consideration.     

Forty years of nonlinear ultrasound

Nonlinear ultrasound forms an integrated discipline of nonlinear acoustics founded in 1755. A short outline of the state-of-the-art in nonlinear ultrasound in 1960 forms the introduction to this paper. Some of the most important contributions to the development in the theoretical, analytical and numerical basis of nonlinear ultrasound and in experimental investigations of nonlinear ultrasonic processes published during the period of 1960 through 2000 are discussed and their successes and failures in practical exploitation are illuminated. A more detailed treatment is given of research achievements in nonlinearity of fluids, in focused ultrasonic field, in parametric acoustic arrays and in thermoacoustics. An attempt is made to point out some fields of research in nonlinear ultrasound where future efforts should be concentrated.     

Global existence in L1 for the Enskog equation and convergence of the solutions to solutions of the Boltzmann equation

For the Enskog equation in a box an existence theorem is proved for initial data with finite mass, energy, and entropy. Then, by letting the diameter of the molecules go to zero, the weak convergence of solutions of the Enskog equation to solutions of the Boltzmann equation is proved.     

Ribonucleotide activation by enzyme ribonucleotide reductase: understanding the role of the enzyme

This article focuses on the first step of the catalytic mechanism for the reduction of ribonucleotides catalyzed by the enzyme Ribonucleotide Reductase (RNR). This corresponds to the activation of the substrate. In this work a large model of the active site region involving 130 atoms was used instead of the minimal gas phase models used in previous works. The ONIOM method was employed to deal with such a large system. The results gave additional information, which previous small models could not provide, allowing a much clearer evaluation of the role of the enzyme in this step. Enzyme-substrate interaction energies, specific transition state stabilization, and substrate steric strain energies were obtained. It was concluded that the transition state is stabilized in 4.0 kcal/mol by specific enzyme-substrate interactions. However, this stabilization is cancelled by the cost in conformational energy for the enzyme to adopt the transition state geometry; the overall result is that the enzyme machinery does not lead to a rate enhancement in this step. It was also found that the substrate binds to the active site with almost no steric strain, emphasizing the complementarity and specificity of the RNR active site for nucleotide binding. The main role of the enzyme at the very beginning of the catalytic cycle was concluded to be to impose stereospecifity upon substrate activation and to protect the enzyme radical from the solvent, rather than to be an reaction rate enhancement.     

Inductive single-electron transistor

We demonstrate a sensitive method of charge detection based on radio-frequency readout of the Josephson inductance of a superconducting single-electron transistor. Charge sensitivity 1.4 x 10(-4) e/square root Hz, limited by a preamplifier, is achieved in an operation mode which takes advantage of the nonlinearity of the Josephson potential. Owing to reactive readout, our setup has more than 2 orders of magnitude lower dissipation than the existing method of radio-frequency electrometry. With an optimized sample, we expect uncoupled energy sensitivity below variant Planck's over h in the same experimental scheme.     

Molecularly imprinted polymers in capillary electrochromatography: recent developments and future trends

The developments in molecularly imprinted polymer (MIP)-based capillary electrochromatography (CEC) achieved during the past years are reviewed in this article. The MIP is prepared using a templated polymerization reaction and results in a material with a high selectivity towards a predetermined target. The selectivity of the MIP is comparable to that of the biological antibodies, however, the MIP is much more stable and is thus able to withstand extremely harsh conditions in terms of pH, temperature, and organic solvents. The high selectivity and stability of the MIP made it an interesting candidate for application as stationary phase sorbent in chromatography. However, due to slow kinetics the efficiency of the early MIP columns, which were predominantly applied in high-performance liquid chromatography (HPLC), were limited. The use of CEC was thought to improve the efficiency of the MIP-based separation system. The small dimensions of the capillary format employed in CEC have put demands on the polymer systems which have resulted in the development of many different polymer formats. Thus, this need for novel MIP formats for applications in CEC has contributed a lot to the general development of MIP formats as well as to the knowledge in MIP synthesis and characteristics.