748 research outputs found
Molar Entropy and Enthalpy of CO Adsorbed in Zeolites as Derived from VTIR Data: Role of Intermolecular Modes
Detailed analysis of recently reported variable-temperature IR (VTIR) spectra of carbon monoxide adsorbed in alkaline zeolites shows how, not only the corresponding values of standard adsorption enthalpy ((Formula presented.)) and entropy ((Formula presented.)) can be obtained, but also the thermodynamic values of molar entropy and enthalpy which characterize the adsorbed gas phase. In addition, it is shown that the so obtained molar entropy data can lead to new insights into soft molecular modes, which would be hardly accessible by conventional IR spectroscopic techniques
Synthesis, characterization, and catalytic properties of AlPO4-40, CoAPO-40, and ZnAPO-40
The experimental conditions leading to the synthesis of pure and highly crystalline AlPO,-40, CoAPO-40, and ZnAPO-40 have been optimized. Although the preparation of these phases is favored by the presence of TMA+ in the synthesis gel, these ions have not been found incorporated in the final AFR structures. All materials have been characterized by powder XRD, t.g./d.s.c.,
SEM, EDX, 13C, 27AI, and 3’P solid-state n.m.r., diffuse reflectance u.v.-vis spectroscopy, FTi.r., and catalytic tests using the n-t-xylene isomerization as a model reaction. This multitechnique
approach provides strong evidence for the framework incorporation of cobalt and zinc. The acid sites generated by the framework insertion of cobalt and zinc are stronger than those generated by the incorporation of silicon
Smart Metering, Water Pricing and Social Media to Stimulate Residential Water Efficiency: Opportunities for the SmartH2O Project
Abstract The SmartH2O project aims to provide water utilities, municipalities and citizens with an ICT enabled platform to design, develop and implement better water management policies using innovative metering, social media and pricing mechanisms. This project has as a working hypothesis that high data quality obtained from smart meters and communicable through social media and other forms of interaction could be used to design and implement innovative and effective water pricing policies. Planned case studies in the UK and Switzerland are introduced. We anticipate that SmartH20 research outcomes will be of use to those interested in linking smart metering, social media and smart pricing approaches to achieve more sustainable water management outcomes
Changing prevalence of asthma in Turin school children between 1994 and 1999
Beckground: Asthma is a widespread chronic disorder in children and its prevalence has been on the increase in Europe. Only few studies have described the prevalence variation in respiratory symptoms in Italian regions. The aim of this study, conducted in Turin during the 1998/1999 school year, is to investigate the distribution of respiratory symptoms in a sample of Turin school children and to compare the obtained results with the findings of the SIDRIA study performed in 1994-95. Methods: the sample in study is composed of all the children attending to three elementary schools in Turin. All of the selected schools had already participated in the 94-95 ISAAC-SIDRIA study. A total of 448 pupils aged 6- 10 years received a standardised questionnaire to be filled by parents. Results: response rate is higher than 97% in all the studies. In 1999 we found that the prevalence of wheezing in the past 12 months was 7.3%. The 13.3% of children had asthma at least once in life and the 5.3% reported an attack in the last year. The comparison of our study results with the ISAACSIDRIA (1994-95) shows that the prevalence of asthma and asthma-like symptoms is rather stable among children, while the prevalence of bronchitis reveals a reduction of about 5.5%, but not statistically significant (p=0.094; 95%CI:-11.9;0.9). A considerable reduction in exposure to parents' passive smoke is shown: ΔP%=-4.7 (95%CI: -9.4;-0.1) for maternal smoking in pregnancy, ΔP%=-8.2 and -15.2, respectively for maternal and paternal smoking in the first two years of life. Conclusions: The results indicate a stable prevalence rate in asthma symptoms in children. A possible explanation of slight variation in asthma prevalence may be due to a reduced exposure to outdoor and indoor risk factors as reported in the questionnaires
Gregariousness in the giant sloth Lestodon (Xenarthra): multi-proxy approach of a bonebed from the Last Maximum Glacial of Argentine Pampas
Megamammals constituted an important component in the Pleistocene faunal communities of South America. Paleobiological and paleoecological studies involving different megamammal taxa have increased significantly in the last years, but there are still several poorly-known issues of its life history. In this work, we analyze an assemblage composed of 13 individuals of different ontogenetic stages, and possibly different sex, belonging to the giant ground sloth Lestodon armatus (Xenarthra, Folivora), recovered from Playa del Barco site (Pampean Region, Argentina). A dating of 19,849 years Cal BP allows assigning this assemblage to a period of the MIS (Marine Isotope Stage) 2 related to the end of the Last Glacial Maximum. Based on multiple lines of research (e.g. taphonomy, paleopathology, osteohistology, isotopy), we interpret the origin of the assemblage and diverse paleobiological and paleoecological aspects (e.g. social behavior, ontogenetic changes, sexual dimorphism, diseases, resource and habitat use, trophic relationships) of L. armatus. Evidence suggests that the assemblage was formed by a local single event of catastrophic mortality, which affected different members of a social group. This record represents the first accurate evidence of gregariousness for this ground sloth, providing new data on a poorly-known behavior among extinct Folivora
Electrical Properties of Meso-Porous Silicon: from a surface effect to Coulomb Blockade and more
Abstract: since the Volker Lehmann's paper "Resistivity of Porous Silicon: a surface effect" published in 1995 [1], a great deal of efforts has been produced in understanding the basic mechanisms ruling the electron transport in Si mesostructures and how these phenomena are affected by external environment. After more than 10 years, new experimental evidences and physical insights have been obtained, like gas sensitivity [2], chemisorption phenomena [3], Coulomb blockade [4] and glassy dynamics In the first half of the '90s, the most studied porous silicon morphology was from high resistivity p-type wafers, because of the high luminescence efficiency. The Lehmann's paper on electrical properties of porous silicon from p+ doped wafers, addressed few unanswered crucial questions regarding resistivity, impurity role, carrier freeze out and surface conditioning proposing a microscopic model of transport in mesoPS, in analogy to submicron channels of CMOS devices, whose figures of telegraph noise are affected by single charge trapping at the oxide-semiconductor interface. In 1999, the first report of strong interaction between mesoporous p+ silicon was announced in Strasbourg, EMRS by our group The successive years were so devoted to a fundamental study of mesoporous silicon in interaction with gas, by means of IR spectroscopy, ESR, NMR and ab-initio calculations Since the former paper of 1999 other groups contributed to study the phenomenon of NO 2 interaction with detailed papers on IR spectroscopy and Drude effect due to free carriers restored by nitrogen dioxid
Wireless Network Virtualization: Opportunities for Sharing in the 3.5 GHz Band
In this paper, we evaluate the opportunities that Wireless Network Virtualization (WNV) can bring for spectrum sharing by focusing on the regulatory framework that has been deployed by the Federal Communications Commission (FCC) for the 3.5GHz band. Pairing this regulatory approach with WNV permits us to present a sharing proposal where emphasis is made on increasing resource availability and providing flexible methods for negotiating for resource access. We include an economics framework that aims at presenting an additional perspective on the attainable outcomes of our sharing proposal. We find that by pairing regulatory flexibility with an enabling technology, within an appropriate economics context, we can increase resource access opportunities and enhance current sharing arrangements
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