Selective electrodesorption based atomic layer deposition (SEBALD): a novel electrochemical route to deposit metal clusters on Ag(111).

The possibility of synergic effects of some metals on the catalytic activity of silver led us to study the way to perform controlled deposition on silver. In fact, many metals of technological interest such as Co, Ni, and Fe cannot be deposited at underpotential on silver, and any attempt to control the deposition at overpotential, even at potentials slightly negative of the Nernst value, did not allow an effective control. However, due to the favorable energy gain involved in the formation of the corresponding sulfides, these metals can be deposited at underpotential on sulfur covered silver. The deposition is surface limited and the successive electrodesorption of sulfur leaves confined clusters of metals. The method can also be used to obtain metal clusters of different size. In fact, the alternate underpotential deposition of elements that form a compound is the basis of the electrochemical atomic layer epitaxy (ECALE), and the reiteration of the basic cycle allows us to obtain sulfide deposits whose thickness increases with the number of cycles. Therefore, the successive selective desorption of sulfur leaves increasing amounts of metals.

Regulatory T cells in the skin lesions and blood of patients with systemic sclerosis and morphoea.

BACKGROUND: Systemic sclerosis (SSc) and morphoea are connective tissue diseases characterized by fibrosis of the skin. Although to date their pathogenesis has not been clearly defined, it is thought that autoimmunity may play a role in the development of the skin lesions observed in both these diseases. As regulatory T cells (Tregs) play a key role in the modulation of immune responses, it has recently been suggested that Treg impairment may lead to the development of autoimmune diseases. OBJECTIVES: To investigate the presence of Tregs and their immunomodulatory cytokines, transforming growth factor (TGF)-beta and interleukin (IL)-10, in patients with SSc and morphoea. PATIENTS/METHODS: Fifteen patients with SSc and 15 with morphoea were enrolled. Immunohistochemistry was applied to identify FoxP3+ (forkhead/winged helix transcription factor) Tregs, TGF-beta+ cells and IL-10+ cells in the skin, cytofluorometry to detect CD4+CD25+FoxP3+ Tregs in the blood, and enzyme-linked immunosorbent assays to analyse TGF-beta and IL-10 serum levels. RESULTS: Fewer FoxP3+ Tregs and TGF-beta+ and IL-10+ cells were found in the skin of patients with scleroderma than in controls. Similarly, there were reduced TGF-beta and IL-10 serum levels and fewer circulating CD4+CD25brightFoxP3+ cells in patients with SSc or morphoea, than in controls. CONCLUSIONS: The quantitative reduction of Tregs, together with that of TGF-beta and IL-10 serum levels, may be responsible for the loss of tolerance observed in both SSc and morphoea.

Multiple physical urticarias.

Physical urticarias are a group of mucocutaneous disorders characterised by the appearance of whealing and/or angioedema and induced by physical stimuli. A 24-year-old Caucasian male affected by ultraviolet A-induced solar urticaria, specific food-dependent exercise-induced anaphylaxis, symptomatic dermographism and allergic rhinoconjunctivitis is described.

Chemical composition and physical features of summer aerosol at Terra Nova Bay and Dome C, Antarctica.

During the 2002-2003 austral summer field season, aerosol samples were collected at a coastal (Terra Nova Bay--Northern Victoria Land) and an inland site (Dome C--East Antarctic Plateau). The sampling was carried out by stacked filter units made up of two filters at different porosity (5.0 and 0.4 microm at Terra Nova Bay and 3.0 and 0.4 microm at Dome C), able to roughly separate a coarse from a fine fraction. At Dome C, a further investigation on aerosol size distribution was performed by an inertial impactor able to collect aerosol particles on 8 size classes (from 10 to 0.4 microm). Atomic Force Microscopy was applied to the filter collecting the finer fraction in both sites in order to assess the real cut-off value of the filter sandwich apparatus and to reconstruct the volume size distribution. At the employed flow conditions, the real cut-off value was revealed to be about one third with respect to the filter nominal porosity in both stations. The size distribution plots showed a bimodal distribution with a mode centered around 0.22 microm in both the sites and a second broader mode which is centered between 0.3 microm and 1.2 microm diameter at Terra Nova Bay and shifted toward higher values (centred around 1.0 microm diameter) at Dome C. Each filter was analysed for the main and trace ionic components allowing evaluation of the contributions of primary and secondary aerosol sources at the two sites as a function of the particle size class. The coastal site is mainly affected by primary and secondary marine inputs: the sea spray contribution (Na+, Mg2+, Cl- and ssSO4(2-)) is dominant (77% w/w) in the coarse fraction whereas the biogenic source (methanesulfonate and nssSO4(2-)) prevails (67.5% w/w) in the fine fraction. In this fraction a significant contribution (15.5% w/w) is provided by ammonium likely to be related to surrounding penguin colonies. Dome C atmosphere is characterised by fine particles arising from secondary sources and long-range transport processes. The main component in the fine and coarse fractions at Dome C is sulfate whose nssSO4(2-) represents the 99.5% and the 92.3%(w/w) in fine and coarse fraction, respectively. The observed agreement between nssSO4(2-) and methanesulfonate temporal profiles in the fine fraction demonstrates that biogenic emissions dominate the inland background aerosol. Results from the sampling by the 8-stage impactor at Dome C are presented here: chloride and nitrate are mainly deposited on the 10-2.1 microm stages while the highest sulfate concentration was found in the submicrometric fraction which turned out to be the most acidic. Such a distribution is able to prevent nitrate and chloride re-emission as gaseous HCl and HNO3 in the 10-2.1 microm stages, arising from the exchange reaction between chloride and nitrate salts and sulfuric acid. Moreover, the concentration peak observed for nitrate in coarser fractions is probably related also to the formation of hygroscopic NH4NO3 particles and nitrate adsorption on sea salt particles.