Precursor synthesis and properties of iron and lithium co-doped cadmium oxide

Journal of Electroceramics - Lithium and iron co-doped cadmium oxide Cd0.9(Li1-xFex)0.1O (x?=?0.1, 0.3, 0.5, 0.7) with NaCl structure has been synthesized using formate of the...     

Biological sensing and interface design in gold island film based localized plasmon transducers

Discontinuous, island-type gold films (typically < or = 10 nm nominal thickness) prepared by evaporation of the metal on transparent substrates show a localized surface plasmon resonance (LSPR) extinction in the visible-to-NIR range and can be used as optical transducers for monitoring local refractive index change. Such transducers, operated in the transmission configuration, provide an effective scheme for label-free biological sensing using basic spectrophotometric equipment. Optimization of the sensitivity of LPSR transducers requires consideration of the distance between the metal island surface and the bound analyte, strongly affecting the optical response due to the fast decay of the evanescent field of localized plasmons. In the present work Au island based LSPR transducers were used to monitor antibody-antigen interactions, demonstrating the effect of the biorecognition interface thickness. Evaporated Au island films derivatized with IgG or hCG antigens were used as biological recognition elements for selective sensing of antibody binding, distinguishing between specific and nonspecific interactions. The LSPR results are supported by XPS and ellipsometry data as well as by AFM and HRSEM imaging, the latter providing actual visualization of the two protein binding steps. Increase of the recognition interface thickness leads to a concomitant decrease in the extinction and wavelength sensitivity, generally conforming to a model of an exponentially decaying surface plasmon (SP) evanescent field.     

Shedding new light on the molecular architecture of oocytes using a combination of synchrotron Fourier transform-infrared and Raman spectroscopic mapping

Synchrotron Fourier transform-infrared (FT-IR) and Raman microspectroscopy were applied to investigate changes in the molecular architecture of mouse oocytes and demonstrate the overall morphology of the maturing oocyte. Here we show that differences were identified between immature mouse oocytes at the germinal vesicle (GV) and mature metaphase II (MII) stage when using this technology, without the introduction of any extrinsic markers, labels, or dyes. GV mouse oocytes were found to have a small, centrally located lipid deposit and another larger polar deposit of similar composition. MII oocytes have very large, centrally located lipid deposits. Each lipid deposit for both cell types contains an inner and outer lipid environment that differs in composition. To assess interoocyte variability, line scans were recorded across the diameter of the oocytes and compared from three independent trials (GV, n = 91; MII, n = 172), and the data were analyzed with principal component analysis (PCA). The average spectra and PCA loading plots show distinct and reproducible changes in the CH stretching region that can be used as molecular maturation markers. The method paves the way for developing an independent assay to assess oocyte status during maturation providing new insights into lipid distribution at the single cell level.     

Quadrefringence of optical vortices in a uniaxial crystal

The splitting of a single optical vortex into four separate ones in a singular beam is theoretically and experimentally described for the propagation of obliquely incident light in a uniaxial crystal. We also find the condition under which the generated vortices in each of the four individual beams propagate independently without changing their structure and have different locations in all beams for any crystal lengths.     

New and Uncommon Fatty Acids in Lipids of Deep-Sea Foraminifera

Fatty acids (FA) of agglutinating foraminifera of two genera, Bathysiphon and Rhabdammina, collected from a depth of 3307–3377 m in the Kuril Basin, Sea of Okhotsk, and adjacent deep‐sea waters of the Pacific Ocean, were analyzed. In lipids of two Bathysiphon species, in addition to common FA typical for marine organisms, the uncommon ?4 and ?7 monoenoic acids and ?4,7‐dienoic acid were found in noticeable amounts. FA of two Rhabdammina species included also such uncommon acids as ?5,8,11,14–21:4, ?5,8,11,14–22:4, and ?5,8,11,14–23:4, which are homologues to arachidonic acid. High levels of cis‐vaccenic and arachidonic acids were typical for lipids of all the studied species. At the same time, we observed a substantial difference in FA composition between members of these two genera. Using GC and GC–MS of FAME, pyrrolidide and DMOX derivatives, the structures of 10 new FA were confirmed: ?4‐i‐16:1 (1.1–0.6%), ?7‐i‐21:1 (0.4%), ?7‐ai‐21:1 (0.3–0.8%), ?4,11–18:2 (0.3–0.9%), ?4,7–20:2 (8.8%), ?7,12–20:2 (0.4–0.6%), ?4,7–21:2 (0.6%), ?7,12–22:2 (6.4–2.1%); ?5,8,11,14–22:4 (1.2–2.0%), and ?5,8,11,14–23:4 (1.7–2.3%). The origin of the new FA and the role of foraminifera FA in deep‐sea communities are discussed.     

Structure and mechanical properties of the compositions of polyisocyanurate polymers with low molecular weight rubbers

The structure and properties of the compositions of polyisocyanurates modified with low molecular weight rubber networks have been investigated by means of dynamical mechanical analysis (DMA), electron microscopy, and stress-relaxation experiments. The network compositions consist of two different polymeric networks. The first component (macrodi-isocyanate based on low molecular weight polybutadiene or copolymers of tetrahydrofuran and propylene oxide) has bulky cross-linked points connected by short flexible chains. The second component (diphenylmethanediisocyanate) also has bulky cross-linked points of the same structure, but the linear fragments between them in this case are very small and rigid. These compositions result in the formation of the heterophase system. As a result, transparent samples were prepared, which differ from the mechanical properties of both the glassy and rubbery polymers. These materials have a modulus of elasticity (from 10³ to 10 MPa) that is usual for the transition zone between the glassy and rubbery states; nevertheless, these materials show elastic (and not viscoelastic) properties. For the materials investigated, the modulus is decreased not more than 10 times in the wide temperature interval from 200 to 500 K. A new state of the polymer, which differs from both the glassy and rubbery states, has been identified in the present case. © 1995 John Wiley & Sons, Inc.     

The H2 role in the synergistic phenomenon in selective NO x reduction by propane over a mechanical mixture of oxide catalysts

The synergistic phenomenon observed in NO _x selective reduction by propane over the mechanical mixture of commercial NTK and Ni-Cr-oxide catalysts is explained by the distinctions in the reaction mechanism over the individual mixture components. Hydrogen formed over Ni-Cr-oxide catalyst in propane oxidation significantly increases the rate of interaction between surface nitrate and acetate complexes. Besides, there is an additional input made by the route of NO _x reduction over NTK in the presence of H₂.     

Microcrystals of antimony compounds in lead–potassium and lead glass and their effect on glass corrosion: a study of historical glass beads using electron microscopy

Crystalline inclusions of antimony compounds in lead glass of the nineteenth century have been investigated by means of transmission electron microscopy, scanning electron microscopy, X-ray microanalysis, electron backscatter diffraction and microcathodoluminescence. Microcrystallites of orthorhombic \(\hbox {KSbOSiO}_4\) (KSS) with the sizes ranging from about 200 nm to several micrometers have been detected in lead–potassium glass of turquoise seed beads prone to a glass disease causing the irrecoverable deterioration of beaded articles kept in museums. The KSS crystals have high number density and tend to form large colonies. Crystallites of cubic \(\hbox {Pb}_2\hbox {Fe}_{0.5}\hbox {Sb}_{1.5}\hbox {O}_{6.5}\) have been detected in stable yellow lead glass beads. Their number density and sizes are much less than those of the KSS particles observed in turquoise glass; they do not form large clusters. We have come to conclusion that KSS precipitates are responsible for the internal strain-induced corrosion of turquoise lead–potassium glass eventually resulting in crumbling of beads to sand particles. The following scenario explains this phenomenon: \(\hbox {K}^+\) and \(\hbox {Sb}^{5+}\) used for glass doping form KSS crystallites during glass melting; tensile strain arising in the glass matrix during cooling because of difference in temperature coefficients of linear expansion of glass and KSS crystals gives rise to crack formation and in course of time results in glass falling apart to heterogeneous pieces. Small crystallites of \(\hbox {Pb}_2\hbox {Fe}_{0.5}\hbox {Sb}_{1.5}\hbox {O}_{6.5}\) cannot induce a sufficient strain to break yellow lead glass, and internal cracks do not arise in this glass during its cooling. This may explain the stability of yellow lead glass.     

Effect of growth conditions on advantages of hup− strain for H2 photoproduction by Rubrivivax gelatinosus

H₂ photoproduction by growing cultures of hup^? mutant and parental strain RL2 of Rubrivivax gelatinosus was compared. We checked the influence of different substrates, presence of air and N₂, culture shaking, inoculum concentrations. At low inoculum concentration, hup^? strain demonstrated significant advantage over the parental strain in microaerobic conditions, while under N₂–Ar atmosphere it was lower and vanished in anaerobic conditions (Ar only). This advantage was evident when using substrates with low degree of reduction (malate and succinate). Culture shaking under microaerobic conditions and in presence of N₂ completely prevented H₂ production by both strains. The high inoculum concentration inhibited H₂ production under microaerobic conditions and in presence of N₂, unlike to anaerobic conditions. With inoculum concentration increase, H₂ production decreased not gradually but stepwise which means some metabolic shift. H₂ production by hup^? strain seems to be more tolerant to air traces than by parental strain.