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Synthesis of Schiff bases derived from 2-aminobenzoic acid
No full textSchiffove baze su spojevi koji se intenzivno istražuju od sedamdesetih godina prošlog stoljeća. Jedan od razloga je jednostavnost pripreme baza te njihova primjena u kemijskim i biološkim procesima. Načini sinteze, kao npr. klasična otopinska sinteza, koja podrazumijeva upotrebu organskih otapala i velik unos energije, polako se zamjenjuju novim alternativnim načinima, a jedan od njih je mehanosinteza. Jedan od najznačajnijih razloga zbog kojeg se istražuju nove metode sinteze je negativni utjecaj otapala na okoliš i količina otapala u reakcijama. Mehanokemija se pokazala kao dobra alternativa jer omogućava metode priprave Schiffovih baza bez upotrebe opasnih otapala te je energetski učinkovitija od klasičnih otopinskih sinteza. Ipak, mehanosinteze su slabo istražene i malo je podataka o utjecaju vlage ili para otapala na reaktivnost aromatskih amina i aldehida u čvrstom stanju. U ovome su radu mehanokemijskom sintezom pripravljene Schiffove baze izvedene iz aldehida i diamina ručnim usitnjavanjem u tarioniku te klasičnom otopinskom sintezom. Analiza spojeva dobivenih mehanosintezom vršila se FTIR spektroskopijom i termičkom analizom (TGA-DSC) pri čemu je ustanovljeno da smo mehanosintezom uspjeli dobiti željene produkte.Schiff base compounds have been intensely researched since 1970's. These compounds are popular research area because of the simplicity of their syntheses and a wide number of applications in chemical and biological processes. Different ways of syntheses, e.g. classic solution synthesis which use organic solutes and require high energy uptake, are slowly being replaced with new alternative procedures such as mechanosynthesis. The main drive for investigation and applications of these new methods is avoidance of negative effects that toxic solvents have on our environment, and also reduction of the amount of solvents used. Thus, mechanochemistry has shown to be a good method for Schiff base syntheses; it gives good yields without the need for hazardous solvents and is also more energy efficient than classic methods are. Nevertheless, mechanosyntheses are still not fully researched and there is a lack of data on the influence of humidity or vapour pressure on the reactivity of aromatic imines and aldehydes in solid state. In this paper Schiff bases derived from aldehydes and amines were synthesized by mechanochemical synthesis by hand grinding with pestle and mortar, and compared to the classic solution synthesis. The synthesized compounds were analysed with FTIR spectroscopy and thermal analysis (TGA- DSC). The results showed that wanted products were adequately synthesized in the process of mechanosynthesis
Mechanochemical synthesis and characterization of supramolecular complexes of cyclodextrin and biologically active ferrocene derivatives
No full textCiklodekstrini su spojevi koji mogu vezati lipofilne molekule lijeka ili lipofilni dio molekule lijeka u svoju centralnu šupljinu te na taj način stvoriti inkluzijske komplekse topljive u vodi što predstavlja oslonac za pripravu novih formulacija i njihovu farmaceutsku primjenu. U ovom radu opisana je sinteza i karakterizacija inkluzijskog kompleksa β-ciklodekstrina s lipofilnim biološki aktivnim derivatom ferocena i jod-uracila (5-jod-N-1,N-3-di{4-[1-(1-ferocenilmetil)-1,2,3-triazol-4-il]metil}-pirimidin-2,4-dion, L1) s dokazanim protutumorskim djelovanjem. Mehanokemijskom sintezom u kugličnom mlinu dobiveni su kompleksi α- i β-ciklodekstrina s ferocenskom kiselinom kao modelni spojevi te ciljani inkluzijski kompleks spoja L1 i β-ciklodekstrina. Pomoću rezultata UV-Vis spektrofotometrijske titracije određena je konstanta stabilnosti inkluzijskog kompleksa u vodi. Za analize kompleksa spojeva nastalih mehanokemijskim reakcijama korištene su termogravimetrijska (TGA) analiza i NMR spektroskopija. Rezultati istraživanja pokazuju kako navedenim postupcima dolazi do stvaranja inkluzijskog kompleksa β-ciklodekstrina i modelnog spoja ferocenske kiseline u vodenoj otopini i mehanokemijski do stvaranja kompleksa β-ciklodekstrina i spoja L1 što je dokazano TGA analizom i NMR spektroskopijom.Cyclodextrins are compounds that can bind lipophilic drug molecules or a lipophilic part of a drug molecule into their central cavity, and thus form water-soluble inclusion complexes, which is the basis for the preparation of new formulations and their pharmaceutical application. This paper describes the synthesis and characterization of the inclusion complex of β-cyclodextrin with a lipophilic biologically active derivative of ferrocene and iodouracil (5-iodo-N-1,N-3-di{4-[1-(1-ferrocenylmethyl)-1,2,3-triazol-4-yl]methyl}-pyrimidine-2,4-dione, L1) with proven antitumor activity. Mechanochemical synthesis in a ball mill yielded complexes of α- and β-cyclodextrin with ferrocenic acid as model compounds, and a target inclusion complex of compound L1 and β-cyclodextrin. The stability constant of the inclusion complex in water was determined by the results of UV-Vis spectrophotometric titration. Thermogravimetric (TGA) analysis and NMR spectroscopy were used to analyze complexes of compounds formed by mechanochemical reactions. The research results show that these methods lead to the formation of an inclusion complex of β-cyclodextrin and a model compound of ferrocenic acid in aqueous solution, and mechanochemically to the formation of a complex of β-cyclodextrin and L1 compound, which was proven by TGA analysis and NMR spectroscopy
Synthesis of Schiff bases derived from 2-aminobenzoic acid
Get PDFSchiffove baze su spojevi koji se intenzivno istražuju od sedamdesetih godina prošlog stoljeća. Jedan od razloga je jednostavnost pripreme baza te njihova primjena u kemijskim i biološkim procesima. Načini sinteze, kao npr. klasična otopinska sinteza, koja podrazumijeva upotrebu organskih otapala i velik unos energije, polako se zamjenjuju novim alternativnim načinima, a jedan od njih je mehanosinteza. Jedan od najznačajnijih razloga zbog kojeg se istražuju nove metode sinteze je negativni utjecaj otapala na okoliš i količina otapala u reakcijama. Mehanokemija se pokazala kao dobra alternativa jer omogućava metode priprave Schiffovih baza bez upotrebe opasnih otapala te je energetski učinkovitija od klasičnih otopinskih sinteza. Ipak, mehanosinteze su slabo istražene i malo je podataka o utjecaju vlage ili para otapala na reaktivnost aromatskih amina i aldehida u čvrstom stanju. U ovome su radu mehanokemijskom sintezom pripravljene Schiffove baze izvedene iz aldehida i diamina ručnim usitnjavanjem u tarioniku te klasičnom otopinskom sintezom. Analiza spojeva dobivenih mehanosintezom vršila se FTIR spektroskopijom i termičkom analizom (TGA-DSC) pri čemu je ustanovljeno da smo mehanosintezom uspjeli dobiti željene produkte.Schiff base compounds have been intensely researched since 1970's. These compounds are popular research area because of the simplicity of their syntheses and a wide number of applications in chemical and biological processes. Different ways of syntheses, e.g. classic solution synthesis which use organic solutes and require high energy uptake, are slowly being replaced with new alternative procedures such as mechanosynthesis. The main drive for investigation and applications of these new methods is avoidance of negative effects that toxic solvents have on our environment, and also reduction of the amount of solvents used. Thus, mechanochemistry has shown to be a good method for Schiff base syntheses; it gives good yields without the need for hazardous solvents and is also more energy efficient than classic methods are. Nevertheless, mechanosyntheses are still not fully researched and there is a lack of data on the influence of humidity or vapour pressure on the reactivity of aromatic imines and aldehydes in solid state. In this paper Schiff bases derived from aldehydes and amines were synthesized by mechanochemical synthesis by hand grinding with pestle and mortar, and compared to the classic solution synthesis. The synthesized compounds were analysed with FTIR spectroscopy and thermal analysis (TGA- DSC). The results showed that wanted products were adequately synthesized in the process of mechanosynthesis
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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