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661.
662.
Analytical and Bioanalytical Chemistry - 相似文献
663.
Johanna Sepp 《Fresenius' Journal of Analytical Chemistry》1960,172(6):441
Ohne Zusammenfassung 相似文献
664.
665.
Jose Luis Ropero-Vega Joshua Felipe Redondo-Ortega Juliana Paola Rodríguez-Caicedo Paola Rondn-Villarreal Johanna Marcela Flrez-Castillo 《Molecules (Basel, Switzerland)》2022,27(9)
The detection of pathogens through alternative methodologies based on electrochemical biosensors is being studied. These devices exhibit remarkable properties, such as simplicity, specificity, and high sensitivity in monitoring pathogens. However, it is necessary to continue conducting studies that adequately improve these characteristics, especially the recognition molecule. This work aims to design and evaluate a new peptide, named PEPTIR-2.0, as a recognition molecule in electrochemical biosensors to detect E. coli O157:H7 in water. PEPTIR-2.0 was obtained from modifications of the PEPTIR-1.0 peptide sequence, which was previously reported and exhibited excellent properties for detecting and quantifying this pathogenic microorganism. PEPTIR-1.0 is a peptide analogous to the TIR (Translocated Intimin Receptor) protein capable of interacting with the Intimin outer membrane. The basis of this study was to obtain, by using bioinformatics tools, a molecule analogous to PEPTIR-1.0 that maintains its three-dimensional structure but increases the hydrophobic interactions between it and Intimin, since these intermolecular forces are the predominant ones. The designed PEPTIR-2.0 peptide was immobilized on screen-printed electrodes modified with gold nanoparticles. The detection capacity of E. coli O157:H7 in water was evaluated using electrochemical impedance spectroscopy in the presence of other microorganisms, such as P. aeruginosa, S. aureus, and non-pathogenic E. coli. The results showed that PEPTIR-2.0 confers remarkable specificity to the biosensor towards detecting E. coli, even higher than PEPTIR-1.0. 相似文献
666.
Dominik Maxein Stephan Kratz Peter Reckenthaeler Johanna Bückers Daniel Haertle Theo Woike Karsten Buse 《Applied physics. B, Lasers and optics》2008,92(4):543-547
Strong light-induced absorption has been observed in lithium niobate crystals doped with magnesium after application of femtosecond
illumination. In this material there are no Nb-on-Li-site defects and hence no antisite polarons occur, but small free polarons
close to the conduction band can be generated. The light-induced absorption observed is attributed to these polarons. For
LiNbO3:Mg, their decay times are about two orders of magnitude smaller than those of the Nb-on-Li-site polarons in undoped material.
The results are relevant for a better understanding of the suppression of the so-called optical damage in these crystals and
for their use in femtosecond applications. 相似文献
667.
Johanna Röder Jörg Faupel Hans-Ulrich Krebs 《Applied Physics A: Materials Science & Processing》2008,93(4):863-867
Complex polymer–metal nanocomposites have a wide range of applications, e.g. as flexible displays and packaging materials.
Pulsed laser deposition was applied to form nanostructured materials consisting of metal clusters (Ag, Au, Pd and Cu) embedded
in a polymer (polycarbonate, PC) matrix. The size and amount of the metal clusters are controlled by the number of laser pulses
hitting the respective targets. For Cu and Pd, smaller clusters and higher cluster densities are obtained as in the cases
of Ag and Au due to a stronger reactivity with the polymers and thus a lower diffusivity. Implantation effects, differences
in metal diffusivity and reactivity on the polymer surfaces, and the coalescence properties are discussed with respect to
the observed microstructures on PC and compared to the metal growth on poly (methyl methacrylate), PMMA. 相似文献
668.
Närväinen J Hubbard PL Kauppinen RA Morris GA 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2010,207(2):242-250
Magnetization transfer (MT) MRI and Z-spectroscopy are tools to study both water-macromolecule interactions and pH-sensitive exchange dynamics between water and the protons of mobile chemical groups within these macromolecules. Both rely on saturation of frequencies offset from water and observation of the on-resonance water signal. In this work, an RF saturation method called Z-spectroscopy with Alternating-Phase Irradiation (ZAPI) is introduced. Based on the T(2)-selectivity of the irradiation pulse, ZAPI can be used to separate the different contributions to a Z-spectrum, as well as to study the T(2) distribution of the macromolecules contributing to the MT signal. ZAPI can be run at resonance for water and with low power, thus minimizing problems with specific absorption rate (SAR) limits in clinical applications. In this paper, physical and practical aspects of ZAPI are discussed and the sequence is applied in vitro to sample systems and in vivo to rat head to demonstrate the method. 相似文献
669.
An alternative formulation of the theory of generalized resonance structures (Clar covers) of single zigzag chains N(n), based on the novel concept of interfaces, is presented. The global structure of every Clar cover can be conveniently expressed as a unique sequence of n interfaces. The complete set of Clar covers is then robustly constructed as the complete set of walks of length \(n+1\) on the associated interface connectivity graph. The presented algorithm is readily generalizable to an arbitrary class of benzenoid structures. 相似文献
670.
A continuous wave distributed feedback diode laser operating in the near infrared at wavelengths close to 1650 nm has been used to measure the extinction of light by single aerosol particles. The technique of optical feedback cavity ring-down spectroscopy (CRDS) was used for measurement of CRDS events at a repetition rate of 1.25 kHz. This very high repetition rate enabled multiple measurements of the extinction of light by single aerosol particles for the first time and demonstrated the dependence of light scattering on the position of a particle within the laser beam. A model is proposed to explain quantitatively this phenomenon. The minimum detectable dimensionless extinction coefficient epsilonmin was determined to be 3x10(-6). Extinction values obtained for single spherical polymer beads from a monodisperse sample of particles of diameter of 4 microm are in near-quantitative agreement with the values calculated by the Mie scattering theory. The deviations from the Mie theory expected for measurement of extinction by CRDS using a continuous wave laser are discussed in the companion paper. 相似文献