1,720,968 research outputs found
Next generation PBWE: Extension of the SAC-FEMA method to high-rise buildings under wind hazards
Full text linkThis paper proposes a method for the Performance-Based Wind Engineering (PBWE) of buildings by extending the well-established SAC-FEMA method originally implemented in seismic engineering for the evaluation of the mean annual frequency (MAF) of pertinent structural Limit States (LSs) in frame buildings. The development of such a method, that we will call the “SAC-FEMA WIND” method, implies the consideration of specific wind engineering peculiarities, like the classification of the across-wind response in two distinct regimes due to buffeting and vortex shedding phenomena, with the consequent adaption of the analysis procedures already defined for earthquakes to these two regimes. The method is then applied for the MAF evaluation of the occupants’ comfort LS for a high-rise steel building: the SAC-FEMA WIND is calibrated by comparing the obtained results with those coming from a Monte Carlo numerical analysis. This allows the definition of appropriate analysis procedures and shows the reliability of the SAC-FEMA WIND in evaluating MAFs. The SAC-FEMA WIND can be viewed as a “next generation” method for PBWE, in the sense that, after years of developments of the PBWE in research, now simplified methods like the SAC-FEMA WIND are needed for the implementation in Standards and in the design practice of explicit probabilistic PBWE approaches
Performance-based multi-hazard engineering (PB-MH-E): The case of steel buildings under earthquake and wind
No full textFocusing on natural hazards as wind and earthquake, the goal of this work is to understand if interference occurs in the design choices for steel buildings of a certain height, thus determining which design requirement and hazard is predominant, between Ultimate Limit State (ULS) requirements under earthquakes, or comfort of the occupants and the Serviceability Limit State (SLS) of the structure under wind. Thus, in order to compare structural responses, both in linear (i.e., SLSs) and non-linear field (i.e., ULS) a simplified analysis procedure that could be also implemented in Standards and in design practice (so-called SAC-FEMA method, originally introduced in the seismic field by Cornell in the early 2000s and more recently extended to the wind) is adapted, leading to a true optimal Performance-Based Multi-Hazard Design (PB-MH-D) of the structure considering the two hazards. The procedure is applied to two case-study steel buildings, 17 and 60 floor heigh; the approach is shown to efficiently lead to a design solution who consistently tackles with the same level of reliability with the two hazards
Influence of the carrier on sunscreens stability and efficacy.
No full textThe research is concerned with the study of sunscreens-carrier interactions using four commercial sunscreens and emollients of different polarity. Influence of the carrier on stability and efficacy of sunscreens was also studied
Comparative conformational and dynamical study of some N-quaternarized UV filters: structure-activity relationships
No full textA comparative conformational and dynamical study of a series of structurally related molecules with UV-filtering properties has been performed in CDCl3 e 2H6DMSO solutions. The main conformers were determined by means of selective spin-lattice proton relaxation rates, carbon spin-lattice relaxation rates and 1D nuclear Overhauser effets. On the basis of these results a possible correlation between conformation and antibacterial activity is discussed
Structure-activity studies in floral odorants.
No full textThis paper reviews the results of our research on the relationships between chemical structure and floral odour, with particular reference to the characteristic note of muguet. Our investigation was aimed at the design and synthesis of substitutes for hydroxycitronellal and other compounds of similar odour, currently employed in perfumery and cosmetics. In order to approach this problem in a systematic way, we have synthesised a great number of tetrahydropyranyl and tetrahydrofuranyl derivatives, as well as other cyclic compounds, that could help modelling the interactions between odorant and receptor proteins, and define the role of each molecular parameter in eliciting the characteristic olfactory note. The compounds exhibiting the best olfactory notes have been used in a conformational analysis, by means of NMR in two different solvents and molecular modelling. A seletion of the odorants synthesised has been also employed in ligand-binding studies, using odorant-binding-proteins purified from nasal mucosa of the bovine and the pig
Synthesis, Crystal Structure and properties of N,N-Dimethyl-N-(6-(benzoyl-4-phenoxy)hexamethylen)-N-n-dodecyl-ammonium bromide: a new substantive UV filter
No full textInprevious paper we have described the synthesis, the substantivity and the antibacterial activity of 4-hydroxy and 2,4-dihydroxy benzophenone derivatives. These properties were affected by the lenght of the n-alkyl chain bonded to the quaternary nitrogen. It would have been of interest to take into consideration also the effect on these properties of the lenght to the methylene chain connecting the oxygen and quaternary nitrogen atoms. In this view we have synthesized N,N-dimethyl-N-(6-(benzoyl-4-phenoxy)hexamethylen)-N-n-dodecil ammonium bromide. Substantivity and antimicrobial properties of this compound have been evaluated and the conformation in the solid state has been determined by single crystal X-ray diffraction. The conformation of the molecule which has been shown to play a fondamental role for the antibacterial activity of these compounds presents an extensive folding of the n-dodecyl chain back towards and along the aromatic moiety. Coiled conformations that have been associated with antibacterial properties and skin irritation phenomena are absent
Conformational analysis by NMR and molecular modelling for designing new floral odorants.
No full textThe aim of the work was to study the conformational parameters of known floral odorants as a basis for designing new molecules with similar odour and different functional groups. The odorants chosen were hydroxycitronellal and lilial, and a serie of THF and THP ethers that best reproduce the typical note of muguet
Nuove molecole odorose. Parametri conformazionali in relazione alle proprietà olfattive.
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