Narrow Results

To investigate the cause of Alzheimer’s disease (senile dementia of Alzheimer’s disease type), we examined aluminium (Al) in the brain (hippocampus) of patients with Alzheimer’s disease using heavy ion (5 MeV Si³⁺) microprobe particle-induced X-ray emission (PIXE) analysis. Heavy ion microprobes (3 MeV Si²⁺) have several times higher sensitivity for Al detection than 2 MeV proton microprobes. We also examined Al in the brain of these patients by energy dispersive X-ray spectroscopy (EDX). (1) Al was detected in the cell nuclei isolated from the brain of patients with Alzheimer’s disease using 5 MeV Si³⁺ microprobe PIXE analysis, and EDX analysis. (2) EDX analysis demonstrated high levels of Al in the nucleolus of nerve cells in frozen sections prepared from the brain of these patients. Our results support the theory that Alzheimer’s disease is caused by accumulation of Al in the nuclei of brain cells.

Picroside II is an active constituent extracted from the traditional Chinese medicine (TCM) Hu-Huang-Lian. To evaluate the neuroprotective effect of picroside II, PC12 cells were treated with glutamate in vitro and male ICR mice were treated with AlCl₃in vivo. Pre-treatment of PC12 cells with picroside II could enhance the cell viability and decrease the level of intracellular reactive oxygen species (ROS) induced by glutamate. By DNA fragmentation and flow cytometry assay, picroside II (1.2 mg/ml) significantly prevented glutamate-induced cell apoptosis. In the animal study, amnesia was induced in mice by AlCl₃ (100 mg/kg/d, i.v.). Pricroside II, at the dose of 20 and 40 mg/kg/d (i.g.), markedly ameliorated AlCl₃-induced learning and memory dysfunctions and attenuated AlCl₃-induced histological changes. This was associated with the significant increased superoxide dismutase (SOD) activity in the brain of experimental mice. All these results indicated that picroside II possessed the therapeutic potential in protecting against neurological injuries damaged by oxidative stress.

A crystal-chemical study of trioctahedral micas previously characterized by single-crystal XRD has been performed by XANES spectroscopy at the Si and Al K edges. XANES, being a local structural probe, can investigate distortion and modification of the tetrahedral sheet with increasing Fe for Mg substitution in the octahedral sheet. Comparison of XANES spectra allows determining the size of the tetrahedral site occupied by either Si or Al. The Si-O distance remains essentially unchanged whereas the Al-O distance appears to increase. The behavior may be interpreted as a tilt of the tetrahedra, initially rotated to match the ideal mica geometry, with increasing Fe substitution in the octahedral sheet.

Chemical pretreatments are often used to improve the adhesion of coatings to aluminium. XPS and AFM were used to study the effect of these pretreatments on the surface chemistry and morphology of Al 5005. Four pretreatments were investigated, an acetone degrease, boiling water immersion, and two sulphuric acid etches, FPL and P2. Degreasing had no affect on surface morphology and simply added to the adventitious carbon on the surface. Boiling water immersion produced a chemically stable pseudo-boehmitic surface that was quite porous. The acid etches produced porous pitted surfaces similar to each other but significantly different to the other surfaces. The surface chemistry of the acid etched surfaces was variable and dependant on atmospheric conditions on removal from etch due to the very active surface that the etch produced.

Aluminium has good corrosion properties and a high strength to weight reduction which makes it favourable in many applications. The increased use of aluminium casting in the automotive industry does also imply that the need for design data for aluminium increases. Especially for castings, the influences of casting defects are always an issue. For this reason fatigue properties for as-cast sand and permanent mould specimens with different contents of porosity have been studied. The cast aluminium specimens of two different porosities were fatigue tested in cyclic axial test at R=-1. Prior to fatigue test specimens were examined by CT-scan and sorted into two quality groups depending on the porosity level.

The aim of this work was to investigate the fatigue life for cast AC4C-T6 alloy with different amounts of inherent porosity. An additional aim was to predict the durability for cast components with defect constrained in a specified volume of components, by using a commercial program MSC. Fatigue.

Al–Si–Cu alloys were cast with the unique gradient solidification technique to produce alloys with two cooling rates corresponding to secondary dendrite arm spacing (SDAS) of ~9 and ~27 μm covering the microstructural fineness of common die cast components. The microstructure was studied with optical microscopy and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electron backscattered diffraction (EBSD). The alloy with higher cooling rate, lower SDAS, has a more homogeneous microstructure with well distributed network of eutectic and intermetallic phases. The results indicate the presence of Al–Fe–Si phases, Al–Cu phases and eutectic Si particles but their type, distribution and amount varies in the two alloys with different SDAS. EBSD analysis was also performed to study the crystallographic orientation relationships in the microstructure. One of the major highlights of this study is the understanding of the eutectic formation mechanism achieved by studying the orientation relationships of the aluminum in the eutectic to the surrounding primary aluminum dendrites.

This paper reports the characterization of the velocity (energy) dependencies of the Al⁺ secondary ion emission produced by 0.5 keV and 5 keV Ne⁺ and Ar⁺ bombardment of polycrystalline pure aluminium. The distributions of secondary Al⁺ ions over their kinetic energy were measured for emission energies of 1–1000 eV without applying electric fields to force the ions into the mass–energy analyzer. To extract the ionization probability, the measured energy distributions of emitted ions were normalized with respect to reference energy distributions of neutral atoms. The reference distributions were obtained by original numerical simulations, as well as analytically, through a sophisticated normalization of the Thompson distribution. It was shown that for both extraction methods, the logarithmic plots of the normalized secondary ion fraction versus the normal component of the reciprocal ion velocity (the reciprocal or inverse velocity plots) are nonmonotonic, with two peaks and two linear portions situated at a low emission energy (E_k=5–25 eV) and at a high emission energy (E_k=80–280 eV). The linear portions were fit by exponential dependency P⁺∝exp(-v₀/v_n) with two different values of the characteristic velocity v₀. For the low emission energy, the value v₀₁~(3.3±0.2)×10⁶cm/s was independent of the mass and energy of the projectiles. However, for the high emission energy, the characteristic velocity depended on the projectile's mass, M, namely v₀₂~(5.3±0.3)×10⁶cm/s for Ne⁺ and v₀₂~(8.1±0.3)×10⁶cm/s for Ar⁺; the ratio v₀₂(Ne⁺)/v₀₂(Ar⁺) is close to the value . This indicates that ballistic mechanisms might contribute to affect the high-energy part of the reciprocal velocity plots along with nonballistic ionization processes, which are generally believed to be the only significant factor for the plots.

In this paper, a high-throughput droplet method is presented for screening corrosion inhibitors, particularly for those metals that are subjected to pitting. To this objective, AA5083 was used as a case study as it is subject to pitting corrosion in saline solution containing different corrosion inhibitors. This paper outlines how critical parameters are measured and calculated (average pit depth and maximum pit depth) and the errors and consistency of the method, and the definition of corrosion inhibition via the method. The results from this method were then compared to the results of inhibition efficiency derived from potentiodynamic polarization scans for inhibitors with a range of performance. The method was conducted at temperature $T=22\pm 2^{\circ }$C inside a humidity chamber, and concentration 10${}^{-3}$ M of seven chemical compounds that have similarities in their structures. The discrepancies were profound for the cases where the inhibitor was of low efficiency, which is ascribed to the fact that these pits’ growth is dominated by that of a few large pits.

Recent developments in the field of manufacturing techniques and alloy development of light materials are reviewed. In the field of manufacturing Aluminium based components, special attention is given to casting, including liquid forging and semi-solid forming technology while for sheet metal forming technology the focus is on material properties and process technology in superplastic forming. For the manufacturing of Magnesium-based components, special attention is given to casting processes and alloy development for casting. For wrought Magnesium, material properties control is covered. For Titanium-based components, an overview of the latest additions to high strength alloys are given, including non-linear elasticity as demonstrated by materials like GUM Metal™. Advanced forming technology such as Levi Casting are also treated.

In this paper a mathematical model for femtosecond laser ablation of metals is proposed, based on standard two-temperature model connected with 1D hydrodynamic equations. Wide-range equation of state has been developed. The simulation results are compared with experimental data for aluminium and copper. A good agreement for both metals with numerical results and experiment shows that this model can be employed for choosing laser parameters to better accuracy in nanoparticles production by ablation of metals.

Reduction behaviour of Fe³⁺/AI₂O₃ obtained by the decomposition of the oxalate precursor has been investigated by employing X-ray diffraction (XRD), Mössbauer spectroscopy and electron paramagnetic resonance (EPR) spectroscopy. Calcination of Fe³⁺/AI₂O₃ at or below 1070 K yields mainly a poorly ordered, fine particulate form of η-Al_2−xFe_xO₃. Calcination at or above 1220 K yields α-AI_2−xFe_xO₃. Reduction of Fe³⁺/AI₂O₃ samples calcined at or below 1070 K gives the FeAI₂O₄ spinel on reduction at 870 K; samples calcined at or above 1220 K give AI_2−xFe_xO₃ with a very small proportion of metallic iron. Fe³⁺/AI₂O₃ samples calcined at 1220 K or above yield metallic iron and a very small proportion of the spinel on reduction below 1270 K. In the samples reduced at or above 1270 K, the main product is metallic iron in both ferromagnetic and superparamagnetic forms. The oxalate precursor route yields more metallic iron than the sol–gel route.

The dry sliding wear behaviour of cast aluminium reinforced with hematite was investigated by means of pin-on-disc wear testing machine. The composite specimens were prepared using liquid metallurgy technique. Wear rates of the composites varying from 0 to 5 % by weight hematite were measured over a load range of 9.81 to 49.05 N at sliding velocities of 1.35,1.8 and 2.25 m / sec. Detailed scanning electron micrography (SEM) was done to verify the effect of addition of hematite on wear mechanism with and without heat treatment. Observations indicate that wear rate of the composites was less than that of the matrix alloy, but increased with the increase in load and the sliding velocity. Heat treatment at 220-degree centigrade upto 5 hours in steps of 2 hours duration improves the wear resistance of the composites.

Civilian and military equipments are used at various places all over the world which requires that the design of the equipment needs to withstand different climatic zones. High and low temperatures can be tested in hot cabinet and freezers. Humidity cycles can be tested in environmental chambers. The microbiological resistance of equipment needs a more advanced procedure. Red dot sights for civilian and military use were inoculated with a mixture of fungi. The test procedure is based on a Military Standard. The functionality and the condition of the sights were checked before and after the test. Five species of fungus Aspergillus niger, Aspergillus flavus, Aspergillus versicolor, Pencillium funiculosum, and Chaetomium globosum were pre-cultured. A mixed spore suspension with a total concentration of 1·10⁶ spores/ml was blended in equal parts. The sights were sprayed with the mixed spore suspension and incubated at 30 °C, relative humidity 95 %, for 30 days in an environmental cabinet. The viability of the mixed spore suspension was checked. The sights passed the functionality test after the fungus test period.

The main motivation for the lightweight concepts in automotive sector is nation and international legislations to decrease the CO₂ emission. The use of lightweight technologies or lightweight materials or the combination of both is indispensable. In this paper we present lightweight technologies which could be used to produce parts with higher performances. Different technologies such as aluminium forming, Plastic forming, Hydroforming and Hot stamping is introduced, where the Trends, Challenges and Solutions are also discussed. Finally a new technology, Hot Tube Forming, based on the existing technologies (Hot stamping and Hydroforming) is presented.