A. Nastro

Rietveld refinement of the zorite structure of ETS-4 molecular sieves

Abstract The crystal structure of ETS-4 titanosilicate [Na9Si12Ti5O38(OH)·12H2O] was refined using synchrotron X-ray powder diffraction and the Rietveld method (Rp=0.050; Rwp=0.063; RB=0.169). Our diffraction data provide direct evidence that ETS-4 has the same structure as the zorite mineral. The framework of zorite can be described as nenadkevichite-like chains, laterally connected by 4[SiO4]/[TiO6] units, corresponding to two different chemical environments for Si. Similar to previous observations, a discrepancy was found between the population ratio of Si positions as calculated by the occupancy refinement of atomic sites related to these two environments, and that inferred from 29 Si MAS NMR. This is tentatively explained here on the basis of the large amounts of protons in the proximity of the Si2 site as indicated by 29 Si CP/MAS NMR. The low thermal stability of the zorite/ETS-4 structure is explained in terms of relevance of the hydrogen bonding between extra framework water molecules and framework oxygens.

Synthesis and characterization of the microporous titanosilicates ETS-4 and ETS-10

In the last years the interest in new zeolitic structures has increased. Some of these materials possess improved catalytic and adsorptive properties in comparison with the classical aluminosilicates. Among these materials are the AlPOs which opened new roads in the study of zeotypes. Subsequently, the study of titanium- and silicon-based molecular sieves was deepened. Among the numerous synthesized structures ETS-10 is a totally synthetic one while ETS-4 is the synthetic counterpart of the mineral zorite. In this paper a complete study is devoted to the ETS-10 and ETS-4 crystallization fields as a function of the quantities of Na2O and TiO2 in the initial gel. The influence of the initial pH on the two phases was also studied. The crystallization curves as a function of time for ETS-10 and ETS-4 with different initial Na and Ti contents were determined and analyzed. The SEM pictures allowed one to determine the morphology of the two ETS phases. Their compositions were determined by chemical analysis, and local structural characteristics were derived from NMR analysis.

Human sperm anatomy: ultrastructural localization of 1α,25-dihydroxyvitamin D3 receptor and its possible role in the human male gamete

Previous studies have suggested that 1α,25‐dihydroxyvitamin D3[1,25(OH)2D3] has a role in reproductive function. Gonadal insufficiencies were observed as a result of 1,25(OH)2D3 deficiency and in 1,25(OH)2D3 receptor (VDR) null mutant mice. To study human sperm anatomy at the molecular level, we first evaluated the ultrastructural localization of VDR by immunogold electron microscopy using a monoclonal antibody against amino acids 344–424 of human VDR, in normozoospermic samples. Intriguingly, VDR was associated predominantly with the cell nucleus. In fact, it is known that VDR is a transcription factor, and that in vitamin‐D‐depleted animals, VDR is largely localized in the cell nucleus. To assess the significance of VDR in the male gamete, we investigated the role of 1,25(OH)2D3/VDR in sperm survival and capacitation. Our results revealed that the action of 1,25(OH)2D3 depended on its concentration because although lower doses induced cholesterol efflux, protein phosphorylation and sperm survival, a higher concentration seemed to be ineffective or did not show an increased effect. These results increase our knowledge of human sperm anatomy at the molecular level and suggest that 1,25(OH)2D3/VDR may have an important role in sperm survival and the acquisition of fertilizing ability.

Photoplethysmography detection by smartphone's videocamera

Smartphones video cameras become more and more powerful while the devices itself become used by many people. That allows utilizing them for many every-day tasks. One of such suitable application of the widely used smartphones is monitoring the state of the health. In this paper we propose an approach to detect the photoplethysmograph signal from the fingertip using a smartphones camera and built-in LED. The proposed solution allows detecting the proper heart rate and is robust to different situations of wrong-usage of the system.

Concrete products with waste's plastic material (bottle, glass, plate)

Plastic material is not easily biodegradable even after a long period, in fact a wide variety of waste materials can be utilized as inert in matrix cement. In this paper we have focused the attention on the use of plastic material particles incorporated as aggregate in concrete and we have evaluated the chemical, physical and mechanical properties

Thermal decomposition of tetrapropylammonium ions progressively incorporated.Into ZSM-5 framework during crystallization

Abstract The thermal decomposition of tetrapropylammonium (TPA) ions incorporated in the channel system of various (M)ZSM-5 zeolites progressively crystallized from [zM 2 O, Al 2 O 3 , 60SiO 2 ] hydrogels (z=0.25,1 or 2;M=Li, Na, K, Rb, Cs) was investigated. Specific DTA endotherms allowed to differentiate TPAOH entities entrapped in Sirich zeolitic frameworks and TPA + counterions to lattice Al-negative centers. The variation of the relative concentration of these species as a function of ZSM-5 particle growth could be related to the mechanism that governs that type of ZSM-5 synthesis. The existence of an Al gradient in the growing crystallites was confirmed.

Synthesis and ion exchange properties of the ETS-4 and ETS-10 microporous crystalline titanosilicates

This paper deals with the ETS-4 and ETS-10 titanosilicates synthesised hydrothermally using titanium (IV) chloride as titanium source, without any organic additives and no seeding. The starting materials were gels of molar composition: 1.49SiO 2 :xNa 2 O:yTiO 2 :0.6KF: 1.28·xHCl:39.5H 2 O, where: 0.5≤x≤2.5 and 0.1≤y≤0.4. By varying the amount of Na 2 O and TiO 2 respectively, the crystallization domains of the titanosilicates mentioned above were found. The optimal gel composition for crystallization was found kinetically. A high purity and crystallinity ETS-10 was obtained for 1.0 mole Na 2 O and 0.2 mole TiO 2 . The ETS-4 and ETS-10 phase mixture is due to a co-crystallization process. The physico-chemical characterisation of these synthesised materials was carried out by XRD, SEM, TG/TDG/DSC, EDS and sorption of 137 Cs and 60 Co radionuclides.

Tetraalkylammonium silicates gels as precursors to zeosilites of different structures

Abstract The endotherms of the pure TAABr and dried TAAOH compounds as well as the endotherms of the TAA + ions occluded in the silicate gels in presence and in absence of sodium cations have been Investigated by thermal analysis methods.

Localized fine accuracy synchronization in Wireless Sensor Network based on consensus approach

This paper focus on the problem of ensuring Wireless Sensor Network (WSN) synchronization for measurement applications. The goal is to guarantee high accuracy synchronization requirements while maintaining at the same time a long network lifetime. In this view, we propose an approach that enforces synchronization accuracy only when it is needed and only in the sub-network of nodes involved in the actual measurement procedures. In such a scheme, traditional synchronization techniques based on master/slaves approaches are not easily employable. This is mainly due to the complications that arise when such a kind of schemes is used to manage synchronization in networks with a variable number of nodes and subject to time-varying transmission topologies. To avoid such a problem, in this paper we propose the adoption of a completely decentralized synchronization approach based on consensus.

Influence of the SiO2/Al2O3 ratio on the synthesis and physicochemical characteristics of levyne-type zeolite

Abstract Levyne-type zeolites were synthesized from gels of initial compositions 4.5Na 2 O-6MeQI- x Al 2 O 3 30SiO 2 -500H 2 O, with MeQ = methylquinuclidinium and 0.6 ≤ x ≥ 3 at 150 ≤ t ≥ 190 °C. The 29 Si NMR spectra show the presence of two crystallographically different sites in the structure. The 27 Al NMR spectra also suggest the presence of two different tetrahedral Al atoms incorporated in the structure. A rather high amount of defect groups SiOM and Si(OM) 2 with M = MeQ, Na and/or H are present in the precursor samples. The Si(OM) 2 groups are eliminated during calcination, and a certain amount of SiOM still persists after calcination. The combined 13 C NMR and thermal analysis data allowed one to interpret the nature of the two different types of MeQ + ions occluded in the levyne channels.