Domain wall contributions to the properties of piezoelectric thin films

In bulk ferroelectric ceramics, extrinsic contributions associated with motion of domain walls and phase boundaries are a significant component of the measured dielectric and piezoelectric response. In thin films, the small grain sizes, substantial residual stresses, and the high concentration of point and line defects change the relative mobility of these boundaries. One of the consequences of this is that thin films typically act as hard piezoelectrics. This paper reviews the literature in this field, emphasizing the difference between the nonlinearities observed in the dielectric and piezoelectric properties of films. The effect of ac field excitation levels, dc bias fields, temperature, and applied mechanical stress are discussed.     

Effect of Heating Rates during Sintering on the Electrical Properties of Ultra-Thin Ni–BaTiO3 Multilayer Ceramic Capacitors

Microstructural control in thin-layer multilayer ceramic capacitors (MLCCs) is one of the present day challenges for increasing capacitive volumetric efficiency and high voltage dielectric properties. The present paper continues a series of investigations aimed at engineering the stability of ultra-thin Ni layers in base-metal electrode MLCCs. A kinetic approach based on the control of sintering profiles is found to not only prevent Ni electrode discontinuities, but also to significantly improve the interfacial electrical properties. Increasing sintering heating rates from 200 to 3000°C/h leads to a decrease in its temperature dependence of capacitance. Faster heating rates also reduce the BaTiO₃ grain size, which is beneficial to the reliability of multilayer capacitors. A direct correlation between heating rates, the thickness of an interfacial (Ni, Ba, and Ti) alloy reaction layer and the interfacial contact resistance has been observed. The decrease in the alloy layer thickness at high heating rates leads to an increased effective Schottky barrier height between the dielectric and electrode toward its theoretical value of 1.25 eV for pure Ni–BaTiO₃ interfaces.     

Improvement in the tribological properties of imidazolium‐derived ionic liquids by additive technology

Molecular design of wear‐preventing and friction‐reducing additives for ionic liquids is described. The tribological properties of carboxylic acid‐derived additives were evaluated by a ball‐on‐flat type tribotest under reciprocating motion. Tetraalkylammonium and tetraalkylphosphonium salts of N‐benzyl‐protected aspartic acid were dissolved in 1‐alkyl‐3‐methylimidazolium‐derived ionic liquids. They prevented wear remarkably and reduced friction fairly. Influences of alkyl group in imidazolium molecule on additive response were observed. In tetraalkylammonium‐derived ionic liquids, the additive reduced wear but did not reduce friction under these conditions. The salt of N‐acetyl‐protected glutamic acid prevented wear, but did not reduce friction. Copyright © 2008 John Wiley & Sons, Ltd.     

Degradation of 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) by brown-rot fungi

Twelve species of brown-rot fungi (BRF) have been investigated for their ability to degrade 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT). In potato dextrose broth (PDB) medium, Gloeophyllum trabeum, Fomitopsis pinicola and Daedalea dickinsii showed a high ability to degrade DDT. 1,1-Dichloro-2,2-bis (4-chlorophenyl) ethane (DDD), 1,1-dichloro-2,2-bis (4-chlorophenyl) ethylene (DDE) and 4,4-dichlorobenzophenone (DBP) were detected as metabolic products of DDT degradation by G. trabeum in PDB medium. The DDT degradation pathway in G. trabeum is proposed, which differs from the proposed pathways in bacteria and other fungi, particularly in the transformation of DDE to DDD. On the other hand, DBP was not detected as a metabolic product of DDT degradation in FeSO(4)-deficient cultures of G. trabeum, whereas DDE and DDD were detected, indicating the involvement of an iron-dependent reaction. Only DBP was detected from DDT, DDE and DDD degradation via a chemical Fenton reaction under conditions similar to those in G. trabeum cultures. These compounds may be directly transformed to DBP via a Fenton reaction.     

Vitrification of high-level radioactive waste considering the behavior of platinum group metals

To demonstrate a method using liquid metal for the removal of PGMs during the vitrification process of high-level radioactive waste, removal of Pd was performed using Cu from molten glass containing fission products such as Nd, Sr, Zr, Mo, Te and Ni. Almost all the Pd, 93%, was extracted into liquid Cu and removed as a separable Cu–Pd metal button from the glass. Tellurium and Ni were also extracted 42 and 5.6%, respectively. Nearly 100% of the other elements, especially the heat generating elements such as Sr and Cs, for which Na was used as a substitute of Cs remained in the glass.     

Nondestructive estimation of fatty acid composition in seeds of Brassica napus L. by near-infrared spectroscopy

The feasibility of near-infrared (NIR) spectroscopy for the nondestructive determination of fatty acid composition in rapeseed was examined. NIR spectra were measured on extracted oil, intact rapeseed kernels, and an intact signle rapeseed with an InfraAlyzer 500 in a syrup cup or a single-grain cup. NIR spectra were scanned from 1100 to 2500 nm at 2-nm intervals. As the percentage of linoleic acid increased, the spectral values in the region 1696–1724 nm, where linoleic acid has its absorption band, became always stronger downward in second-derivative NIR spectra. As the percentage of erucic acid increased the spectral value at 1728 nm, where erucic acid has its absorption band, became always a little bit stronger downward in the second-derivative NIR spectra. On the basis of their NIR spectral patterns, linoleic acid and erucic acid could be successfully determined in both intact seed kernels and in a single seed of rape without damaging them.     

Raman Spectroscopy of Oral Candida Species: Molecular-Scale Analyses,Chemometrics, and Barcode Identification

Oral candidiasis, a common opportunistic infection of the oral cavity, is mainly caused by the following four Candida species (in decreasing incidence rate): Candida albicans, Candida glabrata, Candida tropicalis, and Candida krusei. This study offers in-depth Raman spectroscopy analyses of these species and proposes procedures for an accurate and rapid identification of oral yeast species. We first obtained average spectra for different Candida species and systematically analyzed them in order to decode structural differences among species at the molecular scale. Then, we searched for a statistical validation through a chemometric method based on principal component analysis (PCA). This method was found only partially capable to mechanistically distinguish among Candida species. We thus proposed a new Raman barcoding approach based on an algorithm that converts spectrally deconvoluted Raman sub-bands into barcodes. Barcode-assisted Raman analyses could enable on-site identification in nearly real-time, thus implementing preventive oral control, enabling prompt selection of the most effective drug, and increasing the probability to interrupt disease transmission.