Development aid and international migration to Italy: Does aid reduce irregular flows?

In recent years, donors have claimed to tackle the root causes of migration from low‐income countries using aid. While others have studied the effects of aid on regular migration, we test whether aid deters irregular migration to Italy using two innovative dependent variables: asylum applications and apprehensions at border. For asylum applications, the largest significant effect size implies we should expect one extra application for an additional $162,000 in bilateral aid. For border crossings, the only significant effect implies the marginal cost in bilateral aid is$1.8 million per deterred migrant. The conclusion that effect sizes are small is robust to different types of aid, measures of migration and various controls. We find robust evidence that irregular migration flows are significantly affected by conflict, poverty, and the pre‐existing stocks from that country. Comparing our results to the existing aid‐migration literature, we find similar effect sizes. The cost per deterred (regular) migrant is in the range $4‐7 million. Statistically significant estimates for the effect of aid on regular migration are only found for sub‐samples or specific specifications. In short, aid does not deter regular or irregular migration, so should be used for other purposes

Damage of alumina films by medium energy hydrogen and helium ions

Following previous observations of detachment of amorphous, anodic alumina films from aluminium by 100 keV H+ ions, further experiments have been carried out using H+, D+, 3He+ and 4He+ ions, at energies in the range of 0.5–270 keV, to irradiate anodized aluminium with oxides of thickness from 30 to 500 nm. Surface damage was investigated by field-emission-gun scanning electron microscopy and transmission electron microscopy. Detachment of the oxide, which takes place close to, or at, the metal/oxide interface, occurred only following irradiation by H+ and D+ ions, with the ions being stopped in the metal rather than the oxide. The threshold fluence for initiation of detachment is approximately 3×1015 ions cm−2. No detachment was detected following irradiations by 3He+ and 4He+ ions with fluences up to 5×1016 ions cm−2 and ranges similar to those of H+ and D+ ions, although vacancy production is much greater for helium ions. These findings indicate that detachment is associated with accumulation of hydrogen species in the vicinity of the metal/oxide interface, rather than condensation of vacancies. Such behaviour is consistent with the expected mobility of hydrogen, but not of helium, in aluminium near room temperatur

Anodic oxidation of Mg-Cu and Mg-Zn alloys

Metastable, solid–solution Mg-0.8 at.% Cu and Mg-1.4 at.% Zn alloys have been anodized up to 250 V at 10 mA cm−2 in an alkaline phosphate electrolyte at 293 K in order to investigate the enriching of alloying elements beneath the anodic films. Rutherford backscattering spectroscopy (RBS) revealed enrichments to about 4.1×1015 Cu atoms cm−2 and 5.2×1015 Zn atoms cm−2, which correlate with the higher standard Gibbs free energies per equivalent for formation of copper and zinc oxides relative to that for formation of MgO. The enriched layers were of thickness about 1.5–4.0 nm by medium energy ion scattering (MEIS). The anodic films, composed mainly of magnesium hydroxide, contained copper and zinc species throughout their thicknesses; the Cu:Mg and Zn:Mg atomic ratios were about 18 and 25% of those of the alloys, respectively. Phosphorus species were present in most of the film regions, with a P:Mg atomic ratio of about 0.16. The magnesium ions in the film account for about 30% of the charge passed during anodizing

Influence of nitric acid pre-treatment on Al–Cu alloys

The enrichment of copper alloying additions near the surface of sputtering-deposited Al–1.3 at.%Cu, Al–2.7 at.%Cu and Al–30 at.%Cu alloys is investigated following immersion in nitric acid, which is used commercially as a de-smutting pre-treatment. Corrosion of the alloys is revealed at rates in the range 4–13 nm min−1, leading to enrichment of copper in the alloy surface regions. Enrichments are also generated by nitric acid treatment of AA2024-T3 and AA7075-T6 alloys, with levels similar to those achieved by etching in sodium hydroxide solution. Conventional durations of de-smutting treatments in nitric acid have minor influences on the magnitude of enrichment