1,720,964 research outputs found
Multifunctional polymer nanocomposites with enhanced mechanical and anti-microbial properties
No full textNew ETFE nanocomposatise based on fluoro-modified nanoclays
No full textThree ETFE nanocomposites, containing 1.5% wt in inorganic part, were prepared using melt blending technology. Thermal stability was investigated by thermogravimetric analysis: the decomposition temperature increased of about 20°C. Chemical properties were evaluated by FTIR spectra and the degree of exfoliation was estimated by XRD patterns. Surface characterization through contact angle measurements showed peculiar effects
An ATR-FTIR and ESEM study on magnetic tapes for the assessment of the degradation of historical audio recordings
No full texttThis article presents some approaches for chemical and physical characterization of materials (ATR-FTIR and ESEM) applied to a specific category of cultural material, magnetic tapes. Analogue recordingon magnetic tape has been the main technique for capturing sound for about five decades in the pastcentury. Most of our collective memory is therefore stored on this type of medium, which is unfortunatelydegrading very fast. The past twenty years have witnessed a true rush to digitization in order to savethe information stored on tape, but many aspects of the physical recovery of damaged carriers are stillperformed without solid scientific knowledge, leaving space for improvised treatments with unexpectedill effects. The main motivations for this study are that the preservation of sound recordings is an urgentmatter that belongs to the field of Intangible Cultural Heritage preservation, the scientific literature on thesubject is scarce and little known by the non-scientific archival world, and the documented approaches totapes recovery are currently fragmented and do not provide an exhaustive reference for the operators inthis field. The analyses presented in this article aim at paving the way for the establishment of a scientificprotocol for the safe recovery of damaged tapes
Self-heating of dried industrial tannery wastewater sludge induced by pyrophoric iron sulfides formation
No full textSimilarly to many powders of solids, dried sludge originated from tannery wastewater may result in a self-heating process, under given circumstances. In most cases, it causes a moderate heating (reaching 70-90°C), but larger, off-design residence times in the drier, in a suboxic atmosphere, extremely reactive solids can be produced. Tannery waste contains several chemicals that mostly end up in the wastewater treatment sludge. Unexpected and uncontrolled self heating could lead to a combustion and even to environmental problems. Elaborating on previous studies, with the addition of several analytical determinations, before and after the self-heating, we attempted to formulate a mechanism for the onset of heating. We demonstrated that the system Fe/S/O has been involved in the process. We proved that the formation of small quantities of pyrophoric iron sulfides is the key. They are converted to sulfated by reaction with water and oxygen with exothermic processes. The pyrite/pyrrhotite production depends on the sludge drying process. The oxidation of sulfides to oxides and sulfates through exothermic steps, reasonably catalyzed by metals in the sludge, occurs preferentially in a moist environment. The mechanism has been proved by reproducing in the laboratory prolonged heating under anoxic/suboxic atmosphere
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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