Nanoindentation mapping of mechanical properties of cement paste and natural rocks

This paper reports a study to assess nanoindentation mapping of mechanical properties of cement paste and natural rocks. Initial work seems to show that mechanical property mapping by nanoindentation is feasible and can be related to microscopic information. Further work is however required on the effect of indent size and spacing. Such a testing technique can be very useful for materials with different phases to study the intrinsic properties of each component, and also the interaction and properties of the interfacial regions of different phases. The values of Young's modulus and hardness of the individual mineral phases were also determined by statistically analysing a large number of experimental data.     

Time-coded aperture tomography: experimental results

In this paper, we discuss the applicability of a time-coded aperture system especially designed for thyroid tomography on the basis of phantom experiments. Our studies show that 1) the quality of the reconstructions is high (e.g., a cold spot of 6 mm diameter in a thyroid phantom can easily be detected), and 2) the reconstruction can be carried out in less than 11 min on a standard 16 bit minicomputer (HP1000). It is therefore concluded that the clinical potentiality of the device is good.     

Monte Carlo simulations of microchannel plate detectors. I. Steady-state voltage bias results

X-ray detectors based on straight-channel microchannel plates (MCPs) are a powerful diagnostic tool for two-dimensional, time-resolved imaging and time-resolved x-ray spectroscopy in the fields of laser-driven inertial confinement fusion and fast Z-pinch experiments. Understanding the behavior of microchannel plates as used in such detectors is critical to understanding the data obtained. The subject of this paper is a Monte Carlo computer code we have developed to simulate the electron cascade in a MCP under a static applied voltage. Also included in the simulation is elastic reflection of low-energy electrons from the channel wall, which is important at lower voltages. When model results were compared to measured MCP sensitivities, good agreement was found. Spatial resolution simulations of MCP-based detectors were also presented and found to agree with experimental measurements.     

Ability of methanolic seed extracts of pawpaw (Asiminatriloba) to inhibit n-3 fatty acid oxidation initiated by peroxyl radicals and reactive oxygen,nitrogen, and sulfur

Methanolic extracts from underripe, ripe, and ripe then dried pawpaw seeds (PPSE) were tested for antioxidative effectiveness. Underripe seeds contained more total phenolic compounds than ripe seeds, but ripe seeds showed the highest reducing potential. PPSE samples effectively scavenged DPPH (>86%). PPSE (0–26.8 μM gallic acid) effectively inhibited lipid oxidation biomarkers in 22:6 phosphatidylcholine (PC) liposome suspensions over 7 day’s incubation at room temperature. PPSE inhibited TBARS in 22:6 PC liposome suspensions induced by peroxyl radical generators, free radical generators that produce reactive oxygen, reactive nitrogen, and reactive sulfur species. After 120 min of storage TBARS inhibition by PPSE was in the order of H₂O₂ ? SIN-1 = DSSO = AAPH ? Sulfite > ONOO = MMb > iron/ascorbate. PPSE inhibited lipid oxidation biomarkers in skeletal muscle homogenates induced by iron/ascorbate. The development of value added products from pawpaw seeds may lead to successful commercialisation of this underutilised fruit.     

Exploiting direct and indirect methods for the estimation of the total carotenoid concentration in dried pastas

The total carotenoid concentration (TCC) of several commercially available dried pastas prepared with or without eggs was assessed by means of the two well-established destructive approaches [spectrophotometry (SP) and high-performance liquid chromatography (HPLC)] and three non-destructive, direct (i.e., no sample preparation required) methods (resonance Raman spectroscopy, photoacoustic (PA) spectroscopy and colorimetry). The results obtained by the three direct methods correlate well with the TCC of investigated dried pastas assessed by SP and HPLC. The best linear correlation and detection limit were achieved for the PA method at 470 nm.     

Ab initio and thermodynamic modelling of alloying effects on activity of sacrificial aluminium anodes

This work summarizes the experimental literature to date on Al-alloy sacrificial anodes and shows that the presence of Sn as an alloying element in solid solution form consistently debases the alloy corrosion potential. This study then assesses the lattice expander theory, which states that lattice-expanding dopants can be used to increase Sn solubility in Al and thereby reduce passivation. The thermodynamic effects on Sn solubility of lattice expanders (Ga, Mg, Zr, In and Bi) are predicted with ab-initio methods. Our results support lattice expander theory although we demonstrate that Sn solubility can decrease by alloying with even large dopants if they form compounds with Sn.     

Determination of total polyphenolic content in red wines by means of the combined He-Ne laser optothermal window and Folin-Ciocalteu colorimetry assay

The He-Ne laser (632.8 nm) and the concept of optothermal window (OW), a variant of the open photoacoustic cell, were combined with the Folin-Ciocalteu colorimetry assay to quantitate phenolics in four red wines. The total polyphenolic content in selected red wines varied between 786 and 1630 mg/L gallic acid equivalent (GAE) as determined by OW-Folin-Ciocalteu colorimetry, which compares well to 778 and 1614 mg/L GAE obtained for the same wines by means of classical spectrophotometry. The originality and merit of OW colorimetry used here is that, unlike what is encountered in conventional spectrometry, no intermediate dilution step is required when total polyhenolics are determined in red wine. The precision, defined as the closeness to each other of 256 replicate readings of the OW signal, is generally better than 2%.     

Comparison of Solid-Liquid and Liquid-Liquid Mass Transfer

Mass transfer from solutions of m-acetotoluide, phenacetin and salicylamide into a stationary solvent, water, was studied. A sharp concentration jump was found at the leading solute front for all three liquid-liquid systmes. A comparison was made between the mass transferred in solid-liquid and liquid-liquid systems. The dissolution of m-acetotoluide, phenacetin and salicylamide was compared with mass transfer of solute from solutions with concentrations C_i, 2C_i and C_s into the pure solvent. In all cases, the amount dissolved from the solid was approximated by the C_i or the 2C_i-solvent system with the amount transferred in the C_s-solvent system approximately 100 fold greater than was dissolved from the solid. It was concluded that a concentration much less than saturation exists at the solid-liquid interface and that dissolution of the three compounds studied is controlled by the rate of solvent interaction at the solid surface.