1,721,064 research outputs found
AutoChem: A comprehensive tool for reaction prediction, network generation, and free energy calculation in chemistry
No full textAutoChem is a software package consisting of two modules. The first module is a virtual chemical reactor that can generate reaction products starting from inserted reactants and reactions. The process can be iterated, calculating reactions of the products obtained from the previous steps. To avoid a combinatorial explosion of products, constraints can be inserted. AutoChem module can generate 3D structures of the products obtained as well as a list of all the reactions occurred (chemical network). This can be useful for the calculation of reaction free energies by using computational chemistry programs like Gaussian and ORCA. Usually, the computational step involves the geometry optimization of all products followed by the calculation of vibrational frequencies of the optimized structures, to assess if a local minimum is reached. Finally, when products free energies are obtained, the calculation of the reactions free energies can be done. The second module of Autochem, called check, helps to perform the latter step, launching the jobs, collecting products free energies, restarting false minima and calculating the reactions free energies. This module is intended as a general use even outside AutoChem and might be used to perform a large number of free energy calculations with a little effort from the user. This permits to have results at the level of theory needed. AutoChem might also be used for teaching organic chemistry and basic cheminformatics dealing with SMILES and SMARTS by inserting reactants and reactions and analyzing the products obtained
Prescrizioni antisismiche per impianti tecnologici. La Normativa Europea, la vigente Normativa Italiana di cui al D.M. 14 gennaio 2008 e la Normativa Americana
No full textLa funzionalità degli impianti tecnologici a seguito di un evento calamitoso di tipo sismico concorre, al pari della agibilità della struttura portante, a garantire un adeguato livello di sicurezza e un idoneo livello di operatività dell’edificio. Da ciò la occorrenza di un approccio progettuale antisismico per gli impianti tecnologici similare a quello operato per le strutture portanti, e di conseguenza la necessità di standards progettuali minimi specifici per gli impianti tecnologici.
Nel presente lavoro sono state analizzate alcune prescrizioni inerenti la progettazione antisimica degli impianti tecnologici presenti a livello Comunità Europea, Nazionale ed Extraeuropeo, al fine di definire inizialmente uno stato dell’arte in tale ambito e successivamente impostare un confronto a carattere generale delle disposizioni trattate
Harnessing Biomass for a Sustainable Future: The Role of Starch and Lignin
No full textThe global climate crisis, driven by unchecked industrialization and ecological negligence, compels humanity to seek alternative ways to either avert or mitigate the disastrous environmental phenomena encountered, particularly in recent years. The significant quantities of biomass generated by human activities may serve as important resources for technological applications, and biomass valorization offers dual benefits. This review emphasizes the potential of starch and lignin as adaptable materials for the advancement of sustainable and eco-friendly technologies. By investigating catalytic alterations, we may advance a more sustainable future and tackle the escalating issues of environmental pollution and sustainability. Catalytic alterations of lignin and starch have become essential techniques for their valorization. Biopolymers can be changed into useful chemicals and materials, like levulinic acid, lactic acid, 5-HMF and modified starch, which are used in the paper, textile, and coatings industries. Besides transforming into chemicals, lignin and starch can produce reactive carbon compounds that find application in both classical chemistry and photocatalysis. Additionally, we can use their highly functionalized polymeric matrices as catalysts. We can change the polymeric matrices’ chemical backbone to make them better at speeding up reactions like cross-coupling and multicomponent reactions
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Predicting the UV spectrum of polyoxometalates by TD-DFT
No full textUV absorption spectra of the Lindqvist polyoxometalate [W6O19]2- were predicted by relativistic TD-DFT with several combinations of density functional and basis set. Hybrid functionals with frozen-core Slater basis sets were found to provide the best agreement with experiment while keeping reasonable computational demand. The approach was extended to [W10O32]4- and [PW12O409]3-, suggesting that it can be applied to the POM family
Potential water recovery from biomass boilers: Parametric analysis
No full textA fundamental component of the losses of convection boilers is localized in the warm fumes that are expelled. In the warm fumes, not only energy is lost, but water is also formed from the combustion reaction in the form of steam which is expelled through the exhaust. Modern fuel boilers recover both the heat from the fumes and the latent heat of condensation from water vapor. Depending on the chemical composition of the fuel, different amounts of steam are produced together with heat and different combustion conditions, such as air in excess. In this article, a computational tool was established to simulate a combustion system mainly (but not only) focusing on the prediction of the amount of water produced. In fact, while steam in fossil fuel boilers is commonly condensed, this is not so when the fuel is a biomass. Furthermore, biomasses could contain moisture in different amounts, thus affecting the production of water and the heat of combustion. The study shows that a ten-fold amount of water is formed from biomass combustion with respect to fossil fuels (when the same energy output is produced). As a result, the recovery of water is amenable in biomasses, both from the energetic point of view and for liquid water production. In fact, the water recovered from the fumes might be also reused in other processes such as the cleaning of fumes or agriculture (after treatment)
Role of solute-solvent hydrogen bonds on the ground state and the excited state proton transfer in 3-hydroxyflavone. A systematic spectrophotometric study
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