1,721,004 research outputs found
Studio sull'efficacia preservante degli esteri dell'acido 4-idrossibenzoico in forme cosmetiche.
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Analisi diretta di preservanti in prodotti cosmetici mediante HPLC e spettroscopia derivativa e determinazione dei coefficienti di ripartizione.
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A rapid HPLC technique for determining levels of histamine in tears from normal and inflamed human eyes
No full textBecause of the important role of histamine in the inflammatory process, the measurement of histamine levels in tears has been considered as a possible index of eye irritancy. Histamine levels have been measured using an HPLC procedure involving fluorimetric detection after fluorescamine derivatization. Analyses, at picomole levels, were carried out in less than 5 minutes using 10 μl of tear samples collected from either normal or inflamed human eyes. © 1985
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
New frontiers in sustainable membrane preparation: CyreneTM as green bioderived solvent
No full textIn this work, CyreneTM was employed for the first time as solvent for polyethersulfone (PES) and poly(vinylidene fluoride) (PVDF) membrane preparation via phase inversion. The two selected polymers are among the most required materials in the industrial membrane field. PES and PVDF membranes were prepared by coupling Vapour Induced- and Non-solvent Induced Phase Separation (VIPS and NIPS, respectively) with the aim to study the influence of the adopted operational conditions on the final membrane structure and properties. By changing the exposure time to fixed atmospheric relative humidity (55%) and temperature (25 °C) in the range between 0 and 5 min, membranes with different features, pore size and pure water permeability (PWP) could be tailored. The experimental data were discussed with respect to the casting solution viscosity, ternary phase diagram, membrane morphology, thickness, porosity, contact angle, pore size and PWP. In the case of PVDF, additional differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) analysis were performed for evaluating the polymorphism and crystallinity change of the material, which influences the membrane properties too. By working in complete absence of additives and at room temperature, the combinations PES/CyreneTM and PVDF/CyreneTM allowed to develop a new sustainable approach of producing membranes for potential application in water treatment
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