1,721,212 research outputs found
Study of interactions between polyelectrolyte dispersant, alumina and latex binders by rheological characterization
No full textInfluence of ionic environment and pH on the electrokinetic properties of ball clays
No full textThree ball days (SP from England, TSMA from France and UK from the Ukraine) were characterized for their dry and wet colloidal properties. On the basis of X-ray diffraction and chemical analyses the clays were classified as kaolinite-rich clay, smectitic kaolinite-rich clay and illitic kaolinite-rich clay. The 5 (zeta) potential at the clay-water interface as a function of pH, in three different electrolytes, was investigated using an electroacoustic technique. Starting from measurements of dynamic mobility, the calculated 5 potential was found to be almost constant as a function of pH for the TSMA and UK clays, while it increased from -20 to -60 for the SP clay, when potassium nitrate was used as an electrolyte. The behavior of the three clays in calcium and magnesium nitrate was slightly different: SP showed a smaller increase in 5 potential, while a small deviation from the constant behavior of the UK clay was found. The results are explained in terms of the surrounding-ion atmosphere in light of the chemical-physical properties measured. Our results may well be of use to those involved in ceramic processing
PMA. Programma Motorio Arricchito. Educare allo sviluppo motorio e allo sviluppo delle funzioni esecutive in età prescolare
No full textLa sinergia mente-corpo nel ciclo di vita è oggetto di interesse sempre maggiorper gli psicologi dello sviluppo e dell’educazione. I risultati di ricerche multidisciplinari di kinesiologia, anatomia, neuroscienze
e scienze dello sviluppo e dell’educazione convergono nel riconoscere gli effetti benefici dello svolgimento
regolardi attività motoria sulle prestazioni cognitive e sulle funzioni esecutive, in modo specifico, sia negli adulti che nei bambini (Diamond,2015; Janssen et al., 2014; Lees, Hopkins, 2013).
Tuttavia, ancora carenti e contraddittori sono gli studi realizzati in età prescolae, sebbene la fascia evolutiva
compresa tra tre e cinque anni sia riconosciuta come età sensibile per lo sviluppo sia delle competenze
motorie che delle funzioni esecutive. Infatti, sviluppo motorio e cognitivo seguono traiettorie evolutive parallele
con rapidi cambiamenti in questa particolare fascia evolutiva (Vander Fels et al2015)
PZT film on silicon by electrophoretic deposition
No full textIn recent times direct integration of ferroelectrics on silicon wafer has been attracting interest [1]. Electrophoretic deposition (EPD) was investigated in this laboratory [2] as an alternative mean to produce lead zirconate titanate (PZT) film on silicon wafers followed by sintering at 850-950°C. EPD is an easily implemented deposition technique that requires only basic laboratory gear and a sufficiently stable colloidal suspension to produce ceramic and electroceramic films with thickness in the 100 nm - 10 mm range3 . It has been found that the EPD of niobium-doped lead zirconate titanate (PZTN), performed in ethanol-based suspensions of PZT on bare silicon wafers on which Al/Si alloyed ohmic contacts were made, produced smooth green films that strongly pinned to the silicon substrate after sintering. Thick and well-adhered sintered PZT films on silicon having thickness about 50 µm were thus obtained. Such structures could be the core of novel on-chip sensors/actuators. The results of the production of thick PZT films by EPD and sintering and some characterizations of the same are reported. [1] M. Y. Gureev, A. K. Tangatsev, N. Setter; IEEE T Ultrason Ferr, 58, 1959 (2011) [2] C. Baldisserri, D. Gardini, C. Galassi; Sensor Actuat A-Phys, 174, 123 (2012) [3] P. Sarkar, P.S. Nicholson; J Am Ceram Soc, 79, 1987 (1996
Thermoelectric Materials and Applications: A Review
No full textSolid-state energy conversion has been established as one of the most promising solutions to address the issues related to conventional energy generation. Thermoelectric materials allow direct energy conversion without moving parts and being deprived of greenhouse gases emission, employing lightweight and quiet devices. Current applications, main thermoelectric material classes, and manufacturing methods are the topics of this work; the discussion revolves around the crucial need for highly performing materials in the mid-temperature range, and around the development of more scalable fabrication technologies. The different manufacturing methods for thermoelectric bulk materials and films are also discussed. Small-scale technologies are generating increasing interest in research; the high potential of aerosol jet printing is highlighted, stressing the many advantages of this technology. A promising approach to scale the production of miniaturized thermoelectric devices that combines high energy ball milling and aerosol jet printing is proposed in the conclusion
Thick dielectric films produced by electrophoretic deposition
No full textElectrophoretic deposition (EPD) from colloidal suspensions was utilized for the
preparation of lead zirconate titanate films (PZT) on PZT based substrates. The present
process is developed as a convenient forming process for the development of devices
based on thick ceramic films. The deposition parameters - using EPD - such as colloidal
parameters, deposition voltage and deposition time and the post process parameters, such
as drying velocity and sintering will be controlled. Conductive materials are customarily
used as deposition substrates, but the possibility of depositing on semiconductors (SC)
has recently been demonstrated in this laboratory [1]. This work wants to continue the
research started by Baldisserri et al. that puts emphasis on the analysis of current
transients during constant-voltage deposition as a diagnostic tool for the assessment of
some crucial features of the EPD process [2,3]; the correlations between the above
parameters and final microstructure, by checking the salient features like the film
adhesion, compaction and functionality, will be investigated.
References
[1] C. Baldisserri, D. Gardini, C. Galassi, Sensors & Actuators A 174 (2012) 123.
[2] C. Baldisserri, D. Gardini, C. Galassi, J. Colloid Interface Sci., 347 (2010) 102.
[3] H. Farnoush, J.A. Mohandesi, D. H. Fatmehsari, Ceram. Int., 38 (2012) 6753
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