Advanced Silicon Microstructuring by Electrochemical Micromachining: Technology and Applications

Electrochemical micromachining technology, namely ECM, is a newly proposed microstructuring technique based on electrochemical etching of n-type silicon in aqueous electrolytes containing hydrofluoric acid. Among the main features of ECM there are: i) high aspect-ratio (HAR) of feasible structures, and in turn, high integration density; ii) fine control of etching anisotropy (from 0 to 1), and in turn, enhanced flexibility in fabrication; iii) reduced roughness (about 20 nm) of etched surface. This thesis is aimed at demonstrating that ECM technology can be successfully used for the fabrication of silicon (Si) based microstructures and microsystems for a wide range of applications ranging from integrated optics, to optofluidics, from biology (3D cell culture) to synthesis of nano/micro-structured conducting polymers film. As to optics applications, for the first time, we report fabrication of a novel Si-optical platform where light from standard single mode optical fiber is directly coupled in and out high order vertical silicon/air PhCs operating in the near-infrared region. The platform consists of ECM-micromachined Si-substrate integrating an array of vertical silicon/air PhCs featuring a transmission peak at λ=1.55 μm, together with U-grooves and mechanical end-stop structures for readout optical fibers thus enabling easy-to-use and plug-and-play operation mode. As to optofluidic applications, ECM-fabricated vertical HAR-PhCs were integrated into optofluidic microsystems (OFM) together with fluidic microchannels obtained by potassium hydroxide (KOH) etching. A sensitivity value of 1049 nm/RIU at 1.55 μm and limit of detection of 10-3 RIU are obtained. Moreover, we report the successful application of ECM technology to the realization of all-silicon OFMs in which HAR-PhCs are integrated by one-etching-step together with microfluidic reservoirs/channels and fiber grooves, for alignment/positioning of readout optical fibers in front of the PhC. Assessment of this OFM as refractive index sensor was also performed. High sensitivity of 670 nm/RIU at 1.55 μm and good limit of detection of about 10-3of PhC-OFMs were obtained. As to 3D cell culture applications, we have demonstrated ECM-fabrication of in vitro 3D-microincubators featuring HAR Si-microstructures for mesenchymal cells culturing. In particular, the proposed microincubator selects mesenchymal cells that show the ability to grow in the gaps between two adjacent HAR silicon walls. Finally, we have developed a novel technology for microstructuring polypyrrole (PPy) films based on light-activated PPy electrosynthesis on ECM-micromachined Si-substrates. Scanning electron microscopy highlights as light-activation allows a highly conformal polymer growth yielding a 3D-PPy structure perfectly replicating the Si microstructure

EVOLUZIONE DELLA LAGUNA DI TONNARELLA (MAZARA DEL VALLO, TRAPANI) E SUO ATTUALE VALORE ORNITOLOGICO

Temporal changing of Tonnarella lagoon (Mazara del Vallo, Trapani) and its current ornithological value. Aims of this work were to highlight the importance of a small and artificial recently formed wetland area, that presents different interesting ornithological peculiarities. The Tonnarella lagoon is a breeding site of Little Tern Sternula albifrons and Kentish Plover Charadrius alexandrinus, both classified as “endangered” species in 2011 by the Red List of breeding birds in Italy; the site is considered of “national importance“ for Kentish Plover and “recorded site“ for the Sandwich Tern Sterna sandvicensis, due to the consistency of its wintering populations. Besides, the ornithological importance of this zone increases by the presence of migrating species included in the “Birds” 79/409/CEE Directive and in the Bern, Bonn and Washington international conventions; their status is considered at risk in the near future, according to the most recent estimates in Europe. The value of this area has been also highlighted by the method of evaluation H.A.T., both for breeding and wintering species. Nevertheless, Tonnarella lagoon is at risk of disappearing, because of the competent Authority choices to use it as storage for the dredging of sludge extracted from the harbour of Mazara del Vallo

IL SUCCIACAPRE CAPRIMULGUS EUROPAEUS (Aves Caprimulgiformes) NIDIFICANTE ALLO STAGNONE DI MARSALA (TRAPANI)

First breeding of Nightjar Caprimulgus europaeus (Aves Caprimulgiformes) in the Stagnone di Marsala (Trapani, western Sicily

Nuclear deformation and neutrinoless double-β\beta decay of 94,96^{94,96}Zr, 98,100^{98,100}Mo, 104^{104}Ru, 110^{110}Pd, 128,130^{128,130}Te and 150^{150}Nd nuclei in mass mechanism

The $(\beta ^{-}\beta ^{-})_{0\nu}$ decay of $^{94,96}$Zr, $^{98,100}$Mo, $^{104}$Ru, $^{110}$Pd, $^{128,130}$Te and $^{150}$Nd isotopes for the $0^{+}\to 0^{+}$ transition is studied in the Projected Hartree-Fock-Bogoliubov framework. In our earlier work, the reliability of HFB intrinsic wave functions participating in the $\beta ^{-}\beta ^{-}$ decay of the above mentioned nuclei has been established by obtaining an overall agreement between the theoretically calculated spectroscopic properties, namely yrast spectra, reduced $B(E2$:$0^{+}\to 2^{+})$ transition probabilities, quadrupole moments $Q(2^{+})$, gyromagnetic factors $g(2^{+})$ as well as half-lives $T_{1/2}^{2\nu}$ for the $0^{+}\to 0^{+}$ transition and the available experimental data. In the present work, we study the $(\beta ^{-}\beta ^{-})_{0\nu}$ decay for the $0^{+}\to 0^{+}$ transition in the mass mechanism and extract limits on effective mass of light as well as heavy neutrinos from the observed half-lives $T_{1/2}^{0\nu}(0^{+}\to 0^{+})$ using nuclear transition matrix elements calculated with the same set of wave functions. Further, the effect of deformation on the nuclear transition matrix elements required to study the $(\beta ^{-}\beta ^{-})_{0\nu}$ decay in the mass mechanism is investigated. It is noticed that the deformation effect on nuclear transition matrix elements is of approximately same magnitude in $(\beta ^{-}\beta ^{-})_{2\nu}$ and $(\beta ^{-}\beta ^{-})_{0\nu}$ decay.Comment: 15 pages, 1 figur

White light-emitting diodes for optical stimulation of aluminium oxide in OSL dosimetry

The results of comparative investigations into the optically stimulated luminescence (OSL) of anion-defective corundum excited by radiation of blue and white light-emitting diodes (LEDs) are reported. The continuous-wave OSL (CW-OSL) measurements showed that the white LED (compared to the blue LED) and the chosen geometry allow the amplitude of the OSL response to increase by a factor of more than 40 and the dosimetric information readout time to decrease by a factor of 20. The effect of deep traps on the behavior of the CW-OSL curves of anion-defective corundum was studied. It was found that the filling of deep traps essentially increases the TL yield with a dosimetric peak at 450 K and the CW-OSL-yield under stimulation with blue and white LEDs. It was also found that this filling causes a considerable change in the shape of the OSL curve and the time parameters of the decay. © 2013 Elsevier Ltd. All rights reserved

Comparative antiviral activity of integrase inhibitors in human monocyte-derived macrophages and lymphocytes

The activity of raltegravir and 4 other integrase inhibitors (MK-2048, L870,810, IN2, and IN5) was investigated in primary human macrophages, PBMC and C8166-lymphocytic T cells, in order to determine their relative potency and efficacy in different cellular systems of HIV infection. Raltegravir showed better protective efficacy in all cell types; MK-2048, L870,810 and IN5 showed a potent anti-HIV-1 activity in macrophages, while in lymphocytes only MK-2048 and L870,810 showed an inhibitory effect comparable to raltegravir. IN2 was a poorly effective anti-HIV-1 compound in all cellular systems. All effective integrase inhibitors exhibited a potent antiviral activity against both X4 and R5 HIV-1 strains. In general, raltegravir, MK-2048, L870,810 and IN5 showed anti HIV activity similar or slightly higher in macrophages compared to PBMC and C8166 T cells: for MK-2048, the EC(50) was 0.4, 0.9, 11.5nM in macrophages, in PBMCs and T cells, respectively; for L870,810, the EC(50) was 1.5, 14.3, and 10.6nM, respectively; for IN5 the EC(50) was 0.5, 13.7, and 5.7nM, respectively

Effect of iron doping on the properties of nanopowders and coatings on the basis of Al2O3 produced by pulsed electron beam evaporation

Multiphase nanopowders (NPs) and amorphous/amorphous-nanocrystalline coatings (A-NC) have been prepared by the evaporation of ceramic targets of Al2O3-Fe2O3 (0.1, 3, 5 Fe2O3 mass %) by a pulsed electron beam in vacuum. The specific surface area of NP Al2O3-Fe2O3 reached 277 m2/g. The α and γ phases Al2O3 and other nonidentified phases have been found in the composition of NP Al2O3-Fe2O3. All coatings contained an insignificant fraction of the crystalline γ phase. No secondary phases on the basis of iron have been revealed. According to transmission electron microscopy, the fine fraction of NP Al2O3-Fe2O3 consists of amorphous nanoparticles of an irregular and quasispherical shape no more than 10 nm in size which form agglomerates reaching 1.5 μm. A large fraction of NPs consists of crystal spherical nanoparticles with preferential sizes of about 10-20 nm. All NP Al2O3-Fe2O3 showed ferromagnetic behavior at room temperature. The maximum magnetic response has been established in NPs with a minimum iron content (1.1 mass %). The pulsed cathode luminescence spectra of coatings and NP Al2O3-Fe2O3 have been presented by a wide band in the wavelength range of 300-900 nm regardless of their phase composition. Phase transformations into NP AL2O3-1.1% Fe and coatings from undoped Al2O3 heated to 1400°C occur according to the following scheme: amorphous phase → γ → δ → θ → α, regardless of their initial phase composition. The threshold of thermal stability of the Γ phase in NPs and the coating of undoped Al2O3 does not exceed 830°C. For the first time, the increased thermo and optically stimulated luminescent response comparable with the response of the leading TLD-500K thermoluminescent dosimeter has been reached in A-NC coatings of undoped Al2O3. © 2013 Pleiades Publishing, Ltd