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showing 10 items of 2441 documents
Structural Characterization of Zirconia Nanoparticles Prepared by Microwave-Hydrothermal Synthesis
2009
Nanocrystalline zirconia powders have been prepared by microwave-hydrothermal synthesis starting from aqueous solution of ZrOCl2·8H2O. Results of investigations on the aqueous suspension stability of the washed zirconia nanopowders by dynamic light scattering showed that the suspension, constituted by superaggregates of nanoparticles (131 ± 10 nm), was stable up to 15 days. Nanopowders were investigated by means of transmission electron microscopy and small angle x-ray scattering measurements which proved that the zirconia nanopowder is constituted by small primary nanoparticles of ca. 8 nm that agglomerate forming bigger aggregates of 50 ± 1 nm.
Static and dynamic light scattering by aqueous polyelectrolyte solutions: effect of molecular weight, charge density and added salt
1990
Abstract Aqueous solutions of quaternized poly(2-vinylpyridine) were investigated by static (SLS) and dynamic (DLS) light scattering over a wide range of polyelectrolyte, c pe , and salt concentrations, c s (10 −3 ≤ c pe ≤ 10 2 gl −1 , 10 −5.5 ≤ c s ≤ 10 −1 moll −1 ). Using DLS the cooperative diffusion coefficient D was measured as a function of c pe and c s . D exhibits a characteristic behaviour in each of three different concentration regimes. In the ‘dilute lattice’ regime, where λ = c pe c s ⪡ 1 , one diffusion coefficient is observed. In the transition regime, where λ ≈ 1, D increases with increasing polyelectrolyte concentration and a slow diffusive mode gradually appears. For λ ⪢ 1…
29Si NMR and Small-Angle X-ray Scattering Studies of the Effect of Alkaline Ions (Li+, Na+, and K+) in Silico-Alkaline Sols
1999
Alkali−silica reactions (ASR) which occur in concrete can be simulated in laboratory by destabilization of silico-alkaline aqueous solutions by addition of calcium ions. The relevant features of the reaction depend on the nature of alkaline ions (Li+, Na+, or K+) and on the silica/alkaline ratios which fix the distribution of the molecular species in the precursor solution. 29Si NMR spectroscopy and small-angle X-ray scattering (SAXS) techniques were used to study the structure and size distribution of molecular and colloidal species in sols with different silica/alkaline molar ratio and several types of alkaline ions. Experimental SAXS curves were simulated using a simple structural model …
Exploring automatic grouping procedures in ceramic petrology
2004
Although a small number of studies have attempted to introduce automatic grouping procedures into thin section petrography of archaeological ceramics, the majority of studies continue to be carried out by non-automatic means. Although such an approach with the single observer grouping samples has a number of advantages, it is problematic when dealing with large numbers of samples. This paper aims to explore different coding systems and statistical analyses for grouping ceramic thin sections. In the example discussed a number of variables are defined, codified and analysed by correspondence analysis, classical multidimensional scaling, non-metric isotonic multidimensional scaling and Sammon …
NEW FRAMES OF ARCHAEOMETRICAL DESCRIPTION OF SPINDLE WHORLS: A CASE STUDY OF THE LATE ENEOLITHIC SPINDLE WHORLS FROM THE 1C SITE IN GRÓDEK, DISTRICT …
2010
The essential role of yarn spinning in textile production is indisputable. In this context, spindle whorls, the basic spinning accessories that can be found in the archaeological record, are commonly discussed. Even though the importance of the technical specification of spindle whorls has been already recognized by some authors, their functional characteristics are usually limited to the basic parameters affecting their usage range (i.e., weight, diameter and height). And since the mass moment of inertia of spindle whorls is considered to be a salient index when discussing their technical variability, the descriptions are deficient. With this short study, we intend to implement further res…
Consolidation and protection by nanolime: recent advances for the conservation of the graffiti, Carceri dello Steri Palermo and of the 18th century l…
2014
Abstract Nanolime dispersed in 2-propanol was extensively used for the consolidation of wall paintings. The knowledge of the advances of this methodology dealing with all the possible effects associated with the nanolime new material in conservation is fundamental to assess and improve the technique. In this paper, four different dispersions of Ca(OH) 2 nanoparticles were characterised by Small Angle X-rays Scattering technique (SAXS) and Transmission Electron Microscopy (TEM) in order to achieve information on size, shape, polydispersity, agglomeration, and crystal structure (by SAED patterns) of the particles. Once characterised, the dispersions were tested in two different case studies, …
The Vuelo Ruiz de Alda (1929-30): an exceptional cartographic document. Again about Ilici
2015
Se presenta en este artículo una primera valoración de las posibilidades que para la arqueología, y más concretamente para la estratigrafía del paisaje, encierra un soberbio documento como es la serie fotográfica conocida como Vuelo Ruiz de Alda (1929-30), una vez que los fotogramas han sido ampliamente puestos al alcance de la investigación. Para ello se ponen a prueba las imágenes aplicándolas a dos establecimientos de época ibérica antigua (El Oral y El Molar). Igualmente, se ha retomado una línea de investigación a propósito de la red caminera que afecta al enclave de La Alcudia-Ilici, lo que lleva implícitamente a tratar sobre su catastro romano y la trama parcelaria de todo su entorno…
Energy and Economic Comparison of Different Conditioning System among Traditional and Eco-Sustainable Building
2013
The use of bioclimatic principles can reduce energy demands and CO2 emissions in the building sector [1-. Costs are one of the most important barriers to a widespread adoption of the green architecture technologies [4-. The aim of this study is to compare the energy and economic performances of two buildings: a real residential bioclimatic building located in Cinisi (a small town near Palermo, Sicily) and an imaginary residential building supposed having the same geographical location, cubature, shape and orientation as the bioclimatic building but built by conventional building materials. The tools used for this study were TRNSYS and HOMER
Mapping child maltreatment risk: a 12-year spatio-temporal analysis of neighborhood influences.
2017
Abstract Background ‘Place’ matters in understanding prevalence variations and inequalities in child maltreatment risk. However, most studies examining ecological variations in child maltreatment risk fail to take into account the implications of the spatial and temporal dimensions of neighborhoods. In this study, we conduct a high-resolution small-area study to analyze the influence of neighborhood characteristics on the spatio-temporal epidemiology of child maltreatment risk. Methods We conducted a 12-year (2004–2015) small-area Bayesian spatio-temporal epidemiological study with all families with child maltreatment protection measures in the city of Valencia, Spain. As neighborhood units…
The mediating role of behavioural automaticity and intention on past to future bootcamp attendance
2023
Objective The aim of the current study was to test whether behavioural automaticity and intention mediated the effects of past behaviour on a particular type of vigorous physical exercise: bootcamp attendance. Methods A community sample (N = 69) who had previously attended a bootcamp class was recruited from Queensland, Australia. Participants were asked to complete measures of their previous bootcamp attendance, behavioural automaticity, and intention to attend bootcamps (Time 1). One month later (Time 2), participants were asked to report their bootcamp attendance and behavioural automaticity in the previous month. Data were fitted to a Partial Least Squares-SEM model. Results Past behavi…