1,720,982 research outputs found
An approach for a rapid determination of the aging time of lime putty
No full textA method for determining the effective and long aging time of lime putty, a feature which favors better quality of the corresponding lime mortar, is proposed. Different quicklime precursors were slaked under an excess of water for different times ranging from 3 to 66 months. Each of resulting lime putty was dehydrated by lyophilization and after characterized by thermo-gravimetric analysis (TGA), X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM), and surface area. Taking into account the impurity contents present in the starting quicklime, the mineralogical composition of each lime putty was determined from the weight loss related to the amount of adsorbed water and to the weight losses related to the decomposition of mineral phases present in the lime putty such as brucite, Mg(OH)2, portlandite, Ca(OH)2 and calcite, CaCO3, respectively. The total mineralogical composition of lime putties aged for a time higher than 12 months was close to the expected value of 100%, while such value resulted lower than 100% for lime putties aged for lower times. To justify such result, an incomplete hydration of the quicklime precursor must be considered for lime putties aged for lower times. The delayed hydration can be related to the presence of over burnt of some particles of lime present in the starting quicklime
Simultaneous denitrification, phosphorus recovery and low sulfate production in a recirculated pyrite-packed biofilter (RPPB)
No full textThe simultaneous removal of nitrate (15 mg N-NO3- L−1) and phosphate (12 mg P-PO43- L−1) from nutrient-polluted synthetic water was investigated in a recirculated pyrite-packed biofilter (RPPB) under hydraulic retention time (HRT) ranging from 2 to 11 h. HRT values ≥ 8 h resulted in nitrate and phosphate average removal efficiency (RE) higher than 90% and 70%, respectively. Decrease of HRT to 2 h significantly reduced the RE of both nitrogen and phosphorus. The RPPB showed high resiliency as reactor performance recovered immediately after HRT increase to 5 h. Solid-phase characterization of pyrite granules and backwashing material collected from the RPPB at the end of the study revealed that iron-phosphate, -hydroxide and -sulfate precipitated in the bioreactor. Thermodynamic modeling predicted the formation of S0 during the study. Residence time distribution tests showed semi-complete mixing hydrodynamic flow conditions in the RPPB. The RPPB can be considered an elegant and low-cost technology coupling biological nitrogen removal to the recovery of phosphorus, iron and sulfur via chemical precipitation
I rotoli liturgici della Puglia medievale: scrittura, ideologia, rappresentazione.The liturgical rolls of medieval Puglia: writing, ideology, representation
No full text
Effetto della contaminazione superficiale con ossidi provenienti da acciaio al carbonio sul comportamento a corrosione di armature in acciaio inossidabile
No full textMalte sostenibili per murature in laterizio in zona sismica: uno studio preliminare sulle prestazioni
No full textSono state formulate malte sostenibili mediante sostituzione parziale o totale della sabbia con frazioni di riciclo (sabbia da frantumazione di calcestruzzo demolito o pneumatico triturato) o sostituzione del legante cementizio con legante a ridotto impatto ambientale (geopolimero). Dopo una prima caratterizzazione, le malte sono state usate per la realizzazione di muretti campione, allo scopo di studiarne le prestazioni meccaniche a taglio ai fini della resistenza alle azioni orizzontali
Impiego di vetro espanso come aggregato per calcestruzzi alleggeriti
No full textRIASSUNTO: Tra i materiali di scarto compatibili con la tecnologia del calcestruzzo, il vetro è, tra quelli attualmente riciclati, potenzialmente utilizzabile sotto forma di aggregato espanso per alleggerire il calcestruzzo; l’uso del vetro nel calce¬struzzo pone, tuttavia, dei quesiti sulla durabilità di questo materiale in rela¬zione alla sua scarsa stabilità in ambiente alcalino.
La nota presenta i risultati di una ricerca finalizzata a valutare l’impiego di vetro espanso come aggregato leggero nel calcestruzzo. L’aggregato di vetro espanso è stato caratterizzato in termini di reazione alcali-aggregati, massa volumica, assorbimento e microscopia elettronica. Sostituendo la frazione più fine degli aggregati con vetro espanso, si sono confezionati calcestruzzi con massa volumica modesta (< 2000 kg/m3) e resistenza media a compressione dopo 28 giorni di stagionatura di 25 MPa
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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