Depth profiling and angular dependent XPS analysis of ultra thin oxide film on duplex stainless steel

Thin oxide layers were produced by exposure of polished and sputter-cleaned stainless steel samples to approximately 10⁻⁵ mbar oxygen administered into the fast entry chamber previously pumped down to 10⁻⁸ mbar. XPS as well as AES depth profiling determined principal constituents of the oxide layer as chromium and iron oxides and estimated layers to be in the nanometer range (of the order of 2-3 nm). Since thickness estimations obtained by depth profiling depend on sample stoichiometry, which may be changed by the very process of the profiling measurement, independent determination of oxide layers thicknesses by means of a non-destructive technique was also performed. A simple method was used to estimate oxide layer thickness from the peak intensity ratio vs. emission angle measurements. Full ARXPS was also attempted. For angular dependent XPS measurements, a special tilted sample holder was used to translate the instrument's available sample tilt into an emission angle range from 0 to 75°. Thus, sets of metallic/oxide peaks from Fe 2p_3/2 and Cr 2p_3/2 were measured for different angles. From these data, thickness estimations were derived that were roughly in agreement with thickness estimations obtained from depth profiling data. These estimations were, however, grouped around two distinct values, depending on types of metallic peaks used, which may suggest that even these ultrathin layers are formed of two distinct sublayer types.     

Tin Pest in Sn-0.5Cu Lead-Free Solder Alloys: A Chemical Analysis of Trace Elements

Two samples of Sn-0.5Cu solder alloys, stored at −18°C for 7 years, were chemically analyzed by an inductively coupled plasma-optical emission spectroscopy method. One of the samples was unaffected by this exposure; the other one had completely transformed into brittle α-Sn. Ten elements were found to exhibit statistically significant differences in their concentrations between the two samples, with the higher always associated with the untransformed sample. The highest concentrations were found for elements with an appreciable solubility in Sn, i.e., Bi, In, Pb, and Sb.     

Defensive Components in Insect Eggs: Are Anthraquinones Produced during Egg Development?

Eggs of several insect species are protected against natural enemies by noxious components. However, almost nothing is known about the fate of these defensive substances during egg development nor their site of biosynthesis. The eggs of several leaf beetle species of the taxon Galerucini contain components that are unusual in insects: 1,8-dihydroxylated anthraquinones and anthrones that deter predators such as ants and birds. These components, i.e., the anthrones dithranol and chrysarobin, and the anthraquinones chrysazin and chrysophanol, are not sequestered from host plants. We asked whether the amounts of these components in the overwintering eggs of Galeruca tanaceti change from deposition to larval hatching. Gas chromatography-mass spectroscopy (GC-MS) analyses of eggs revealed a significant decrease in total amounts of dithranol and chrysophanol from egg deposition in autumn to the next spring 5 months later. Thus, these results do not provide any hint of active anthraquinone biosynthesis within eggs. Instead, the anthrones and anthraquinones that must be incorporated by the female into the eggs seem to be degraded to some extent either by the embryo or endosymbionts. GC-MS analyses showed that parasitization of eggs had some effects on the quantities of anthrones and anthraquinones.     

Gene expression in synovial membrane cells after intraarticular delivery of plasmid-linked superparamagnetic iron oxide particles--a preliminary study in sheep

This study evaluated in vivo gene delivery and subsequent gene expression within cells of the synovium in the presence of static and pulsating magnetic field application following intraarticular injection of superparamagnetic iron oxide nanoparticles linked to plasmids containing reporter genes encoding for fluorescent proteins. Plasmids encoding genes for either green fluorescent protein or red fluorescent protein were bound to superparamagnetic nanoparticles coated with polyethyleneimine. Larger (200-250 nm) and smaller (50 nm) nanoparticles were compared to evaluate the effects of size on transfection efficiency as well as any associated intraarticular reaction. Comparisons between groups were evaluated at 24, 72, and 120 h time periods. Inflammatory response was mild to moderate for all injected particles, but was present in the majority of synovial membrane samples evaluated. Larger particles tended to be associated with more inflammation than smaller ones. Nevertheless, intraarticular application of both experimental and control nanoparticles were well tolerated clinically. Gene expression as determined by observation of either green or red intracellular fluorescence was difficult to assess by both epifluorescent light, and confocal microscopy. An insufficient concentration of nanoparticles in relation to joint volume likely resulted in a limited number of samples with positive evidence of iron staining and with suspected positive evidence of cells expressing fluorescent proteins. Our results indicate that intraarticular administration of functionalized superparamagnetic iron oxide nanoparticles resulted in a mild to moderate synovitis and there was in conclusive evidence of gene expression. Further research is warranted to determine the best and most effective reporter assay for assessment of the in vivo gene delivery into the joints. In addition, the best suited concentration and size of nanoparticles, which will optimize gene delivery and expression, while minimizing intraarticular inflammation, needs to be determined.     

Uptake and biocompatibility of functionalized poly(vinylalcohol) coated superparamagnetic maghemite nanoparticles by synoviocytes in vitro

Superparamagnetic iron oxide nanoparticles (SPION) were coated with either Polyvinyl alcohol (PVA) or Vinyl alcohol/vinyl amine copolymer and further functionalized with the fluorochromes Cy3.5 or Texas Red. A colloidally stable suspension of nanoparticles was incubated on sheep synovial cells in vitro for 3, 24, 72, and 120 hours. Nanoparticle internalization into synoviocytes as well as biocompatibility was visualized using light, fluorescence and confocal microscopy and fluorochrome labeled cells were quantified by flow cytometry. Data were analyzed by ANOVA factorial tests. Amino-PVA-SPION alone was detectable in cytoplasmic endosome-like structures after 3 hours of incubation but resulted in early cell death after 24 hours. Although amino-PVA-Cy3.5-SPION and PVA-TexasRed-SPION were taken up more slowly and less intensely, both labeled more than 80% of the cells in culture, but did not significantly change cell morphology or vitality at any time of evaluation in comparison to control cells. Results indicate that functionalized amino PVA-coated SPION are biocompatible, were successfully internalized by synoviocytes and hold promise for future biomedical applications utilizing magnetic drug targeting in joint disease.     

Multiple-Approach Evaluation of WSP Coatings Adhesion/Cohesion Strength

Adhesion/cohesion testing represents one of the most common methods for benchmarking and optimization of thermal spray coatings. However, owing to the inhomogeneous coating microstructure, such testing may be quite troublesome. In this study, adhesion/cohesion strength of representative metallic and ceramic coatings deposited by water-stabilized plasma (WSP) spraying was evaluated by four different methods: tensile adhesion test, pin test, tubular coating tensile test, and shear test. Combination of various methods enabled the evaluation of the coating adhesion/cohesion strength under different loading conditions. Limitations and benefits of each method for testing of WSP coatings are demonstrated. Dominating failure micromechanisms were determined by supplementary fractographic analysis.     

S‐layer Coated Emulsomes as Potential Nanocarriers

The present study introduces a novel nanocarrier system comprising lipidic emulsomes and S‐layer (fusion) proteins as functionalizing tools coating the surface. Emulsomes composed of a solid tripalmitin core and a phospholipid shell are created reproducibly with an average diameter of approximately 300 nm using temperature‐controlled extrusion steps. Both wildtype (wt) and recombinant (r) S‐layer protein SbsB of Geobacillus stearothermophilus PV72/p2 are capable of forming coherent crystalline envelope structures with oblique (p1) lattice symmetry, as evidenced by transmission electron microscopy. Upon coating with wtSbsB, positive charge of emulsomes shifts to a highly negative zeta potential, whereas those coated with rSbsB become charge neutral. This observation is attributed to the presence of a negatively charged glycan, the secondary cell wall polymer (SCWP), which is associated only with wtSbsB. The present study shows for the first time the ability of recombinant and wildtype S‐layer proteins to cover the entire surface of emulsomes with its characteristic crystalline lattice. Furthermore, in vitro cell culture studies reveal that S‐layer coated emulsomes can be uptaken by human liver carcinoma cells (HepG2) without showing any significant cytotoxicity over a wide range of concentrations. The utilization of S‐layer fusion proteins equipped in a nanopatterned fashion by identical or diverse functions may lead to further development of emulsomes in nanomedicine, especially for drug delivery and targeting.     

Inhibitory effect of marinades with hibiscus extract on formation of heterocyclic aromatic amines and sensory quality of fried beef patties

Heterocyclic aromatic amines (HAA) are carcinogenic compounds found in the crust of fried meat. The objective was to examine the possibility of inhibiting HAA formation in fried beef patties by using marinades with different concentrations of hibiscus extract (Hibiscus sabdariffa) (0.2, 0.4, 0.6, 0.8 g/100 g). After frying, patties were analyzed for 15 different HAA by HPLC-analysis. Four HAA MeIQx (0.3–0.6 ng/g), PhIP (0.02–0.06 ng/g), co-mutagenic norharmane (0.4–0.7 ng/g), and harmane (0.8–1.1 ng/g) were found at low levels. The concentration of MeIQx was reduced by about 50% and 40% by applying marinades containing the highest amount of extract compared to sunflower oil and control marinade, respectively. The antioxidant capacity (TEAC-Assay/Folin–Ciocalteu-Assay) was determined as 0.9, 1.7, 2.6 and 3.5 μmol Trolox antioxidant equivalents and total phenolic compounds were 49, 97, 146 and 195 μg/g marinade. In sensory ranking tests, marinated and fried patties were not significantly different (p > 0.05) to control samples.