Surface chemical and morphological modifications of as-plated and Cr(III)-passivated monophasic zinc-nickel coatings induced by corrosion in chloride solutions are demonstrated. The passivated samples showed slower anodic dissolution, less significant de-alloying, smaller surface dezincification and lower coating cracking, as demonstrated by Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDX) of the surface and inductively coupled plasma atomic emission spectroscopy solution analysis. Surface characterization by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and SEM-EDS indicated simonkolleite as the main corrosion product for both, as-plated and Cr(III)-passivated coatings. In contrast, only for as-plated coating, which experienced higher cracking, new Ni containing phases (metallic Ni and NiO) were evidenced. The phase transition via selective dissolution of zinc is supposed to increase the concentration of the structural defects and could explain cracking in the non-passivated Zn-Ni coating.
To demonstrate the importance of sample preparation used in Fourier transform infrared (FTIR) spectroscopy of microbiological materials, bacterial biomass samples with and without grinding and after different drying periods (1.5–23 h at 45 °C), as well as biogenic selenium nanoparticles (SeNPs; without washing and after one to three washing steps) were comparatively studied by transmission FTIR spectroscopy. For preparing bacterial biomass samples, Azospirillum brasilense Sp7 and A. baldaniorum Sp245 (earlier known as A. brasilense Sp245) were used. The SeNPs were obtained using A. brasilense Sp7 incubated with selenite. Grinding of the biomass samples was shown to result in slight downshifting of the bands related to cellular poly-3-hydroxybutyrate (PHB) present in the samples in small amounts (under ~10%), reflecting its partial crystallisation. Drying for 23 h was shown to give more reproducible FTIR spectra of bacterial samples. SeNPs were shown to contain capping layers of proteins, polysaccharides and lipids. The as-prepared SeNPs contained significant amounts of carboxylated components in their bioorganic capping, which appeared to be weakly bound and were largely removed after washing. Spectroscopic characteristics and changes induced by various sample preparation steps are discussed with regard to optimising sample treatment procedures for FTIR spectroscopic analyses of microbiological specimens. 相似文献
A model of elasto-plastic flow combined with the two-temperature model in a two-dimensional approximation has been developed
to describe microbump and nanojet formation observed recently on nanosize gold films irradiated by femtosecond laser pulses.
It has been shown that the effect of microbump and nanojet formation is conditioned by the elastic characteristics, yield
stress, and other properties that are unique for gold. The numerical results are in excellent agreement with the experimental
data with respect to a number of parameters, particularly the threshold fluence for nanojet formation at the tops of microbumps,
which occurs nearby and above the melting threshold. The analysis of properties for a number of materials is performed and
some other materials are discussed as possible candidates for nanotexturing of thin films by femtosecond laser pulses.
PACS 79.20.Ds; 42.62.-b 相似文献
Developing a novel, small‐sized molecular building block that may be capable of emitting light in the solid state is a challenging task and has rarely been reported in the literature. BF2‐containing dyes seem to be promising candidates towards this aim. Two series of new N^NBF2 complexes showing aggregation‐induced emission (AIE) and aggregation‐induced emission enhancement (AIEE) were designed and synthesized by means of a new protocol, which improved on the traditional method by employing microwave irradiation. The optical and photophysical properties of the BF2 complexes were investigated in depth. The synthesized complexes showed fluorescence in both solution and the solid state and, in a mixture of tetrahydrofuran/water, may aggregate into fluorescent nanoparticles. The experimental investigation was supported by quantum mechanical calculations. Their availability, stability, large Stokes shifts, and aggregation capabilities, along with their solid‐state emission capability, render this new class of BF2 complexes promising AIEE/AIE fluorophores for further applications in the fields of fluorescence imaging and materials science. 相似文献
As part of our general QSPR treatment of solubility (started in the preceding paper), we now present quantitative relationships between solvent structures and the solvation free energies of individual solutes. Solvation free energies of 80 diverse organic solutes are each modeled in a range from 15 to 82 solvents using our CODESSA PRO software. Significant correlations (in terms of squared correlation coefficient) are found for all the 80 solutes: the best fit is obtained for n-propylamine (R(2) = 0.996); the lowest R(2) corresponds to toluene (0.604). 相似文献
A method was developed for the preparation of macrocyclic 2-alkylcycloalkanones by alkylation of 2-carbethoxy--cyclothienones with subsequent desulfurization and ketone cleavage. Only C-alkylation occurs under the described conditions (potassium metal in hexamethylphosphoric triamide, sodium hydride in dioxane).See [1] for communication XIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 16–21, January, 1973. 相似文献
Nucleoside base analogs in which fluoro substituents replace the enolic hydroxy groups of uracil, thymine and cytosine have been prepared. Improved methods for the preparation and isolation of the known 2,4-di-fluoropyrimidine, 2,4-difluoro-6-methylpyrimidine and the new 2,4-difluoro-5-methylpyrimidine, 2-fluoro-4-aminopyrimidine, 4-fluoro-2-aminopyrimidine, and other alkylaminofluoropyrimidines are described. 相似文献
Rhodium-catalysed hydroformylation of styrene and aliphatic olefins under biphasic conditions in the presence of watersoluble 1,4,7-triaza-9-phosphatricyclo[5.3.2.14,9]tridecane (CAP) chemoselectively affords aldehydes. Multiple catalyst reuse without loss in performance is demonstrated. 相似文献