Capsule-free fluid delivery and beam-induced electrodeposition in a scanning electron microscope

Gold coated borosilicate nanocapillaries are used to locally deliver aqueous, electrolytic CuSO4 solution into the low vacuum chamber of an environmental scanning electron microscope (ESEM). Capillary flow of the liquid is induced by bringing a nanocapillary into contact with a substrate. A microscopic droplet is stabilized by controlling the droplet evaporation rate with the substrate temperature and the pressure of H2O vapor injected into the vacuum chamber. An electron beam is admitted to the droplet through a pressure limiting aperture. Electrochemical reduction of aqueous Cu2+ to solid, high purity, deposited Cu is achieved by biasing the nanocapillary and supplying current by the beam which acts as a virtual cathode and enables electrodeposition on both conductive and insulating substrates. Delivery of liquids into vacuum enables localized, capsule-free beam induced electrochemistry, opening new pathways for direct-write nano and micro-lithography via beam induced electrodeposition. © The Royal Society of Chemistry 2013

Deposition of highly porous nanocrystalline platinum on functionalized substrates through fluorine-induced decomposition of Pt(PF<inf>3</inf>) <inf>4</inf> adsorbates

Nanocrystalline platinum is synthesized at room temperature by co-injecting Pt(PF3)4 and XeF2 vapors onto solid supports in vacuum. The Pt nucleation time scales with chemisorbed fluorine coverage, which is controlled by pre-dosing supports with XeF2, and by optional electron or ion beam irradiation under flowing XeF2. The latter is used to increase the chemisorbed fluorine coverage and localize the Pt growth process. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Magnetotransport properties of iron microwires fabricated by focused electron beam induced autocatalytic growth

We have prepared iron microwires in a combination of focused electron beam induced deposition (FEBID) and autocatalytic growth from the iron pentacarbonyl, Fe(CO)5, precursor gas under UHV conditions. The electrical transport properties of the microwires were investigated and it was found that the temperature dependence of the longitudinal resistivity (rhoxx) shows a typical metallic behaviour with a room temperature value of about 88 micro{\Omega} cm. In order to investigate the magnetotransport properties we have measured the isothermal Hall-resistivities in the range between 4.2 K and 260 K. From these measurements positive values for the ordinary and the anomalous Hall coefficients were derived. The relation between anomalous Hall resistivity (rhoAN) and longitudinal resistivity is quadratic, rhoAN rho^2 xx, revealing an intrinsic origin of the anomalous Hall effect. Finally, at low temperature in the transversal geometry a negative magnetoresistance of about 0.2 % was measured

Spontaneous Growth of Gallium-Filled Microcapillaries on Ion-Bombarded GaN

Bottom-up growth of microscopic pillars is observed at room temperature on GaN irradiated with a Ga+ beam in a gaseous XeF2 environment. Ion bombardment produces Ga droplets which evolve into pillars, each comprised of a spherical Ga cap atop a Ga-fille

Maskless milling of diamond by a focused oxygen ion beam

Recent advances in focused ion beam technology have enabled high-resolution, maskless nanofabrication using light ions. Studies with light ions to date have, however, focused on milling of materials where sub-surface ion beam damage does not inhibit device performance. Here we report on maskless milling of single crystal diamond using a focused beam of oxygen ions. Material quality is assessed by Raman and luminescence analysis, and reveals that the damage layer generated by oxygen ions can be removed by non-intrusive post-processing methods such as localised electron beam induced chemical etching

Direct-write milling of diamond by a focused oxygen ion beam

Recent advances in focused ion beam technology have enabled high-resolution, direct-write nanofabrication using light ions. Studies with light ions to date have, however, focused on milling of materials where sub-surface ion beam damage does not inhibit device performance. Here we report on direct-write milling of single crystal diamond using a focused beam of oxygen ions. Material quality is assessed by Raman and luminescence analysis, and reveals that the damage layer generated by oxygen ions can be removed by nonintrusive post-processing methods such as localised electron beam induced chemical etching

Explaining Africa’s public consumption procyclicality : revisiting old evidence

This paper compiles a novel dataset of time-varying measures of government consumption cyclicality for a panel of 46 African economies between 1960 and 2014. Government consumption has, generally, been highly procyclical over time in this group of countries. However, sample averages hide serious heterogeneity across countries with the majority of them showing procyclical behavior despite some positive signs of graduation from the “procyclicality trap” in a few cases. By means of weighted least squares regressions, we find that more developed African economies tend to have a smaller degree of government consumption procyclicality. Countries with higher social fragmentation and those are more reliant on foreign aid inflows tend to have a more procyclical government consumption policy. Better governance promotes counter- cyclical fiscal policy whileincreased democracy dampens it. Finally, some fiscal rules are important in curbing the procyclical behavior of government consumption.info:eu-repo/semantics/publishedVersio

Scope and constraints for tree planting in the irrigated landscapes of the Aral Sea Basin : case studies in Khorezm Region, Uzbekistan

A wealth of research papers, reports, and newsprint demonstrate the wide international interest in the ecological deterioration in the Aral Sea Basin in Central Asia (CA). The demise of the Aral Sea is a symptom that results from intensive agricultural activities aiming at maximizing agricultural production while neglecting environmental sustainability, as exemplified by the land use patterns also prevalent in the Republic of Uzbekistan, one of the five newly established states in CA. The environmental degradation is acute and continues, since various factors conducive to it have not been eradicated. This discussion paper deals with the potential role of forestry-based production systems and in their contribution to counterbalancing the ecological landscape demise in the region. This discussion paper starts with a brief overview of environmental conditions in CA, followed by a discussion of forestry and agroforestry in CA’s irrigated semi-arid and arid landscapes. The paper focuses on Uzbekistan, and more specifically the province (viloyat) of Khorezm, which is located at the southern rim of the Aral Sea Basin and serves as an example for the Middle Asia lowlands. The results of surveys on farmers’ perception of forest and tree products, as well as the outcomes of field measurements of the productivity of tree stands and agroforestry systems, regional forestry governance, and the market situation for timber products are discussed. Following data mining of secondary sources, field, market and household surveys, combined with in-depth analyses using remote sensing techniques, the paper re-assesses the tree resources of Uzbekistan and concludes that the present use and management of trees and forests is inadequate. Well-designed multi-species windbreaks are absent (single-tree rows of mulberry comprise about 50% of the present tree strips), only 70% of the tree windbreaks were oriented in the North-South and North/West-South/East directions, from which the highest wind speeds (>3 m s -1) are generally measured, and the majority of the investigated tree strips did not satisfy the minimal height of 5 m. More than half (55%) of the strips did not stretch over the entire length of the related field. However, other structural criteria such as stand porosity and width had acceptable values. In the hedgerow systems monitored tree planting schemes varied considerably but on average were much lower compared to the recommended planting schemes by forestry administrations as the perennial crops were of more importance to the farmers. The farmers planted mostly fruit trees to increase income and improve their food basket, but none of the ca. 100 interviewed was ecologically motivated. However, the total land area of the various surveyed agroforestry systems on both private and rented land was the largest where tree age did not exceed 12 years, thus indicating the interest of tree planting. The surveys results are followed by a review of forestry policies in Uzbekistan. The paper concludes with a set of recommendations concerning managerial and research needs for forest and agroforestry systems in irrigated drylands of CA, and outlines the opportunities and need for external support at both the country and sub-regional level. Despite the role trees could potentially play, the lack of training of the farming population, reduced capacities of the forestry administration and their staff as well as shortcomings in the forest legislation have resulted in many underperforming “goodwill” efforts. Due to the complexity of the social, economical and physical components and their interdependencies, this paper calls for integrated knowledge generation, concerted action and for administrative and research support. The crisis in the Aral Sea Basin has a strong global dimension, which calls for targeted support at both country and international donor community levels

Analysis of a spatial gene expression database for sea anemone Nematostella vectensis during early development

International audienceThe spatial distribution of many genes has been visualized during the embryonic development in the starlet sea anemone Nematostella vectensis in the last decade. In situ hybridization images are available in the Kahi Kai gene expression database, and a method has been developed to quantify spatial gene expression patterns of N. vectensis. In this paper, gene expression quantification is performed on a wide range of gene expression patterns from this database and descriptions of observed expression domains are stored in a separate database for further analysis