experimental and numerical analyses of a spark ignition engine firing with n butanol gasoline blends at high load operation

Abstract In this paper, the potential of alcohol-gasoline blends as fuels for spark-ignition engines has been evaluated. The general purpose of the work is to verify the possibility of incrementing the bio-fuels penetration in the market of transportation fuels. As it is well known, bio-mass derived fuels, in fact, could significantly reduce the CO2 emissions of energy thermal systems. The behavior of a small, turbocharged spark-ignition engine, firing with gasoline-butanol blends, has been analyzed. Analyses have been carried out by means of both experimental tests and numerical simulations. In previous works, engine main performances have been illustrated and discussed. Here, experimental tests have been carried out in order to compare the engine knock resistance and the obtainable fuel conversion efficiency when the engine is fueled by pure gasoline or gasoline-butanol blends at high load operation. Furthermore, one dimensional numerical analyses have been utilized in order to compare the engine behavior, at different operating points, when it is firing with pure gasoline or pure butanol. In general, the obtained results seem to indicate that butanol (produced by bio-masses) is a viable alternative to fossil fuels in the way of CO2 emission reduction

The first solvent-free cyclotrimerization reaction of arylethynes catalyzed by rhodium porphyrins

Different rhodium(III) porphyrin chlorides have been used as catalysts for the cyclotrimerization of several arylethynes, giving in many cases high yields in substituted benzenes and selectivities based on the steric hindrance of the macrocycles and on the substitution of the substrates

Finding the Center of Mass of a Soft Spring

This article shows how to use calculus to find the center of mass position of a soft cylindrical helical spring that is suspended vertically. The spring is non-uniformly stretched by the action of gravity. A general expression for the vertical position of the center of mass is obtained.Comment: LaTeX, 7 pages, 2 figures. Minor changes to agree with published versio

Panchromatic light harvesting and stabilizing charge-separated states in corrole–phthalocyanine conjugates through coordinating a subphthalocyanine

Owing to the electron-donating and -accepting nature of corroles (Corr) and phthalocyanines (Pc), respectively, we designed and developed two novel covalently linked Corr-Pc conjugates. The synthetic route allows the preparation of the target conjugates in satisfying yields. Comprehensive steady-state absorption, fluorescence, and electrochemical assays enabled insights into energy and electron-transfer processes upon photoexcitation. Coordinating a pyridine-appended subphthalocyanine (SubPc) to the Pc of the conjugate sets up the ways and means to realize the first example of an array composed by three different porphyrinoids, which drives a cascade of energy and charge-transfer processes. Importantly, the SubPc assists in stabilizing the charge-separated state, that is, one-electron oxidized Corr and the one electron-reduced Pc, upon photoexcitation by means of a reductive charge transfer to the SubPc. To the best of our knowledge, this is the first case of an intramolecular oxidation of a Corr within electron-donor–acceptor conjugates by means of just photoexcitation. Moreover, the combination of Corr, Pc, and SubPc guarantees panchromatic absorption across the visible range of the solar spectrum, with the SubPc covering the „green gap“ that usually affects porphyrinoids

Echoes from a long time ago: Chewbacca inflation

The cosmic microwave background (CMB) radiation offers a unique avenue for exploring the early Universe's dynamics and evolution. In this paper, we delve into the fascinating realm of slow-roll inflation, contextualizing the primordial acoustic perturbations as the resonant echoes akin to the iconic sound of Chewbacca from the Star Wars universe. By extrapolating polynomial potentials for these primordial sounds, we illuminate their role in shaping the inflationary landscape. Leveraging this framework, we calculate the scalar spectral index ($n_s$) and tensor-to-scalar ratio ($r$), providing insights into the underlying physics governing the inflationary epoch. Employing a rigorous chi-square ($\chi^2$) analysis, we meticulously scrutinize the Planck data combined with that offered by the BICEP/Keck collaboration to identify the Chewbacca sound profile that best aligns with observational constraints. Our findings not only shed light on the intricate interplay between sound and cosmology but also unveil intriguing parallels between the cosmic symphony of the early universe and beloved cultural icons.Comment: 8 pages + references, 5 figures. Prepared for submission to the Annals of Improbable Research on April 1st 2024. Find "The Sound of the Big Bang" in the audio folder of the source fil

Wild birds of the Italian Middle Ages: diet, environment and society

Wild birds are intrinsically associated with our perception of the Middle Ages. They often feature in heraldic designs, paintings, and books of hours; few human activities typify the medieval period better than falconry. Prominent in medieval iconography, wild birds feature less frequently in written sources (as they were rarely the subject of trade transactions or legal documents) but they can be abundant in archaeological sites. In this paper we highlight the nature of wild bird exploitation in Italian medieval societies, ranging from their role as food items to their status and symbolic importance. A survey of 13 Italian medieval sites corresponding to 19 ‘period sites’, dated from the fifth to the fifteenth centuries, reveals the occurrence of more than 100 species (certainly an under-estimate of the actual number). Anseriformes and Columbiformes played a prominent role in the mid- and late medieval Italian diet, though Passeriformes and wild Galliformes were also important. In the late Middle Ages, there is an increase in species diversity and in the role of hunting as an important marker of social status