oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 16 )

2019 ( 197 )

2018 ( 248 )

2017 ( 271 )

Custom range...

Search Results: 1 - 10 of 189994 matches for " VALLI G "
All listed articles are free for downloading (OA Articles)
Page 1 /189994
Display every page Item
A TGA/FT-IR study for measuring OC and EC in aerosol samples
P. Fermo, A. Piazzalunga, R. Vecchi, G. Valli,M. Ceriani
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2006,
Abstract: Carbon analysis consists in the evaluation of the carbonaceous content of the aerosol (TC) but, more importantly, of its distribution between the two components EC (Elemental Carbon) and OC (Organic Carbon) that are characterized by different physical-chemical properties. In spite of the numerous studies focused on this topic, nowadays a universal methodology for the determination of the two components EC and OC is not available. In fact OC and EC (also known as black carbon or soot) are operationally defined by the method of analysis and, as a consequence, different methods can produce different results. In this paper we present results on the application of TGA/FT-IR (Thermo-gravimetric Analysis/Fourier Transformed Infrared Spectroscopy) to the characterization of carbonaceous aerosols. The analytical methodology was applied to PM10 (particulate matter with aerodynamic diameter smaller than 10 μm) four-hour time resolution samples collected in Milan urban area. The method is a two-steps thermal one and it is based on the different thermal behaviour of OC and EC. It has been set up analyzing suitable standards containing both organic and elemental carbon. Carbon quantification is achieved by on-line, continuous monitoring of CO2 infrared absorption at 2361 cm 1. A good separation between OC and EC on particulate matter (PM) samples has been obtained. Ranges and average values were 12–70 μg/m3 and 20 μg/m3 for OC and 0.2–6 μg/m3 and 2 μg/m3 for EC. On average OC and EC made up 29 (±13)% and 2.5 (±1.8)% of the PM10 fraction, respectively. The method reliability has been verified by a preliminary comparison with TOT (Thermal Optical Transmission) technique. OC and EC values determined for ambient samples of PM10 were correlated with meteorological parameters as well as with Radon concentrations. Final Revised Paper (PDF, 1331 KB) Discussion Paper (ACPD) Special Issue Citation: Fermo, P., Piazzalunga, A., Vecchi, R., Valli, G., and Ceriani, M.: A TGA/FT-IR study for measuring OC and EC in aerosol samples, Atmos. Chem. Phys., 6, 255-266, doi:10.5194/acp-6-255-2006, 2006. Bibtex EndNote Reference Manager XML
Technical Note: On the effect of water-soluble compounds removal on EC quantification by TOT analysis in urban aerosol samples
A. Piazzalunga, V. Bernardoni, P. Fermo, G. Valli,R. Vecchi
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2011,
Abstract: In this work, three different thermal protocols were tested on untreated and water-washed aerosol samples to study the influence of soluble organic and inorganic compounds on EC measurements. Moreover, analyses on the water soluble extracts were carried out. The aim was to find out the most suitable protocol to analyse samples collected in a heavily polluted area. Indeed, the tests were performed on real samples collected at an urban background station in the Po Valley, which is one of the main pollution hot-spots in Europe. The main differences among the tested protocols were the maximum temperature of the He step (i.e. 870 °C, 650 °C, and 580 °C) and the duration of the plateaus during the heating procedure. Our measurements evidenced the presence of a significant amount of weakly light-absorbing carbonaceous aerosol evolving during the highest temperature step in He (i.e. 870 °C), which makes lower temperature protocols not suitable for EC determination in samples collected in heavily polluted areas like Milan.
Morphometry Examination of Placenta in Birth Weight of Full-Term Newborns in Puducherry, India
V. Kowsalya,R. Vijayakumar,G. Valli,K.P. Bharath
Pakistan Journal of Biological Sciences , 2013,
Abstract: Birth weight is an important determinant of child survival, healthy growth and development. Low birth weight is a well-established risk factor for adverse long term health, particularly cardiovascular disease and metabolic syndrome. The ability of the fetus to grow and thrive in utero is presumed to be a function of the placenta. The present study was aimed to assess the morphometry examination of placenta in normal and low birth weight babies in the Union territory of Puducherry. Morphometry examination includes Placenta weight, number of cotyledons, maternal and fetal surface area and site of umbilical cord insertion were measured in normal and low birth weigh babies. Result showed among 200 subjects, mean birth weight of normal and low birth babies were 2806 and 2058 g, respectively. The prevalence rate of low birth babies (less than 2500 g) was 22%. The placental morphometry study namely placental weight, number of cotyledons, maternal and fetal surface area and insertion of umbilical cord at centre were significantly (p<0.001) reduced in the low birth weight babies when compared with normal birth weight babies. Study revealed that morphometry analysis of placenta significantly influences the birth weight of new born. In conclusion, study recommends the early measurements of placenta by non-invasive techniques like ultrasonography will be helpful in early prediction of low birth weight fetus in utero itself and for better management to avoid such low birth weight.
INSILICO DRUG ACTIVITY OF N-OXIDES
VALLI G,LALITHISWARI T,JOTHIMALAR S,JOTHIMALAR S
International Journal of Bioinformatics Research , 2011,
Abstract: N-Oxides were found to have antimicrobial activity. In continuation of our work on synthesis, characterizationand biological activities (in vitro method) of N-Oxides and knowing their biological activities against micro organisms, wehave correlated the biological activity of these N-Oxides against the micro organisms like Staphylococcus aureus,Salmonella typhi “H”, Escherichia Coli, Pseudomonas aeruginosa, Klebsiella aerogenes, Enterobacteraerogenes,Citrobacter, Staphylococcus epidermidis, and Aeromonas hydrophila by Insilico method. The target molecules(microorganism) were taken from Protein data bank. Various soft wares were used to find out the drug likeness propertiesof these N-Oxides. Online software “Molinspiration” was used to calculate log P (ie) Hydrophobicity of a drug. ACD/Chemsketch was used to draw the structures of N-Oxides. Hex 4.2, docking software was used to predict the drugactivities of these N-Oxides. The drug activities were measured in terms of drug likeness property by recording the ETotalvalue and compared with the marketed standard drugs for the above micro organism infections. Standard drugswere taken from drug bank. As per the standard norms, it was observed that the compounds that have negative E-Totalvalues could be used as a drug. We have selected Ceftazidime ,Cefepime and Ceftizoxime as standard drugs among theavailable drugs for these microorganism for correlating the drug activities of these N-Oxides. We observed that some ofour N-Oxides were found to have higher drug activities compared to standard drugs.
A TGA/FT-IR study for measuring OC and EC in aerosol samples
P. Fermo,A. Piazzalunga,R. Vecchi,G. Valli
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2006,
Abstract: Carbon analysis consists in the evaluation of the carbonaceous content of the aerosol (TC) but, more importantly, of its distribution between the two components EC (Elemental Carbon) and OC (Organic Carbon) that are characterized by different physical-chemical properties. In spite of the numerous studies focused on this topic, nowadays a universal methodology for the determination of the two components EC and OC is not available. In fact OC and EC (also known as black carbon or soot) are operationally defined by the method of analysis and, as a consequence, different methods can produce different results. In this paper we present results on the application of TGA/FT-IR (Thermo-gravimetric Analysis/Fourier Transformed Infrared Spectroscopy) to the characterization of carbonaceous aerosols. The analytical methodology was applied to PM10 (particulate matter with aerodynamic diameter smaller than 10 μm) four-hour time resolution samples collected in Milan urban area. The method is a two-steps thermal one and it is based on the different thermal behaviour of OC and EC. It has been set up analyzing suitable standards containing both organic and elemental carbon. Carbon quantification is achieved by on-line, continuous monitoring of CO2 infrared absorption at 2361 cm 1. A good separation between OC and EC on particulate matter (PM) samples has been obtained. Ranges and average values were 12–70 μg/m3 and 20 μg/m3 for OC and 0.2–6 μg/m3 and 2 μg/m3 for EC. On average OC and EC made up 29 (±13)% and 2.5 (±1.8)% of the PM10 fraction, respectively. The method reliability has been verified by a preliminary comparison with TOT (Thermal Optical Transmission) technique. OC and EC values determined for ambient samples of PM10 were correlated with meteorological parameters as well as with Radon concentrations.
PHENOTIPIC AND GENOTIPIC CHARACTERIZATION OF SALMONELLA SPP ISOLATED FROM MOLLUSCAN SHELLFISH IN MARCHE REGION
M.B. Valli,M. Staffolani,G. Blasi,E. Rocchegiani
Italian Journal of Food Safety , 2013, DOI: 10.4081/ijfs.2008.4.67
Abstract: Salmonella enterica is a major epidemic cause of gastrointestinal infection worldwide. Although the animal host is believed to be the primary habitat of this specie, Salmonella is frequently isolated from water sources and it has been identified in marine environments. In this study the incidence of serotypes of Salmonella in the coastal water of the Italian region of Marche on the Adriatic Sea was evaluated. A total of 3985 samples of molluscan shellfish were analyzed during routine surveillance activity for a period of five years (2002-2007) and 0,95% of the samples were found contaminated with Salmonella. The most prevalent serotypes were Seftenberg (23.5%), Typhimurium (14,7%) and Enteritidis (11.8%) respectively. Pulsed-field electrophoresis and phage typing were used to determine possible genetic relationship (relatedness) between S. Enteritidis strains isolated from bivalve mollusc and those isolated from human cases, animals and foods in Region of Marche. Three isolates from mollusc shellfish, 7 from sporadic human infection and 4 from poultry farms were confirmed as phagetype PT2 and PFGE profile XB0002. These results suggest a molecular fingerprinting relationship among shellfish, human and animal isolates, which could be considered as preliminary evidence of human infections associated with poultry production industry.
Correlation effects in transport properties of interacting nanostructures
A. Valli,G. Sangiovanni,A. Toschi,K. Held
Physics , 2013, DOI: 10.1103/PhysRevB.86.115418
Abstract: We discuss how to apply many-body methods to correlated nanoscopic systems, and provide general criteria of validity for a treatment at the dynamical mean field theory (DMFT) approximation level, in which local correlations are taken into account, while non-local ones are neglected. In this respect, we consider one of the most difficult cases for DMFT, namely for a quasi-one-dimensional molecule such as a benzene ring. The comparison against a numerically exact solution shows that non-local spatial correlations are relevant only in the limit of weak coupling between the molecule and the metallic leads and of low inter-atomic connectivity, otherwise DMFT provides a quantitative description of the system. As an application we investigate the role of correlations on electronic transport in quantum junctions, and we show that a local Mott-Hubbard crossover is a robust phenomenon in sharp nanoscopic contacts.
Fourier transformation and response functions
O. Gunnarsson,G. Sangiovanni,A. Valli,M. W. Haverkort
Physics , 2010, DOI: 10.1103/PhysRevB.82.233104
Abstract: We improve on Fourier transforms (FT) between imaginary time $\tau$ and imaginary frequency $\omega_n$ used in certain quantum cluster approaches using the Hirsch-Fye method. The asymptotic behavior of the electron Green's function can be improved by using a "sumrule" boundary condition for a spline. For response functions a two-dimensional FT of a singular function is required. We show how this can be done efficiently by splitting off a one-dimensional part containing the singularity and by performing a semi-analytical FT for the remaining more innocent two-dimensional part.
Double Exchange model for nanoscopic clusters
D. Rotter,A. Valli,G. Sangiovanni,K. Held
Physics , 2012, DOI: 10.1140/epjb/e2012-30829-y
Abstract: We solve the double exchange model on nanoscopic clusters exactly, and specifically consider a six-site benzene-like nanocluster. This simple model is an ideal testbed for studying magnetism in nanoclusters and for validating approximations such as the dynamical mean field theory (DMFT). Non-local correlations arise between neighboring localized spins due to the Hund's rule coupling, favoring a short-range magnetic order of ferro- or antiferromagnetic type. For a geometry with more neighboring sites or a sufficiently strong hybridization between leads and the nanocluster, these non-local correlations are less relevant, and DMFT can be applied reliably.
In memoriam: Angus Maddison's Mission to Understand the World and its History through Numbers
Valli, Vittorio
The European Journal of Comparative Economics , 2010,
Abstract: Angus Maddison's contribution to the analysis of long-run developments in the world economy has been monumental. His continuous cumulative work on an ever expanding data-set of national accounts and his in-depth analysis of changes in the main trends in the world's economic history has given us fundamental tools for a better understanding of past secular trends and future scenarios. His tentative estimates of total and per capita income in remote times must be considered important preliminary building stones in the process of cumulative learning. His main contributions to our knowledge of world economic changes, briefly surveyed in this paper, will be treasured by generations of scholars of comparative growth and development and of economic historians
Page 1 /189994
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.