121 research outputs found
Direct Synthesis of Thioesters from Feedstock Chemicals and Elemental Sulfur
No full textThe development of a mild, atom- and step-economical catalytic strategy that effectively generates value-added molecules directly from readily available commodity chemicals is a central goal of organic synthesis. In this context, the thiol-ene click chemistry for carbon-sulfur (C-S) bond construction has found widespread applications in the synthesis of pharmaceuticals and functional materials. In contrast, the selective carbonyl thiyl radical addition to carbon-carbon multiple bonds remains underdeveloped. Herein, we report a carbonyl thiyl radical-based thioester synthesis through three-component coupling from feedstock aldehydes, alkenes, or alkynes and elemental sulfur by direct photocatalyzed hydrogen atom transfer. This method represents an orthogonal strategy to the conventional thiol-based nucleophilic substitution and exhibits a remarkably broad substrate scope ranging from simple commodity chemicals such as ethylene and acetylene to complex pharmaceutical molecules. This protocol can be easily extended to the synthesis of thiolactones, oligomer/polymers, and thioacids. Its synthetic utility has been demonstrated by a two-step synthesis of the drug esonarimod. Mechanistic studies indicate that the use of elemental sulfur to trap acyl radicals is both thermodynamically and kinetically favored, illustrating its great potential for the synthesis of sulfur-containing molecules
Hierarchical hollow ZnO cubes constructed using self-sacrificial ZIF-8 frameworks and their enhanced benzene gas-sensing properties
No full text
Novel hierarchical ZnO hollow cubes are constructed using the interpenetrated 0D nanoparticles through directly decomposing the Zn-based metal-organic frameworks (Zn-MOF, ZIF-8). After decomposition at 450 degrees C for 1 h, the as-prepared ZnO well maintains the original ZIF-8 shape with relatively high surface area (45 m(2) g(-1)), thereby realizing fast surface reaction kinetics of benzene molecules. In contrast to singular 0D ZnO nanoscale counterparts, the unique ZnO nanostructure assembly renders the well exposed surfaces and defect states, enhancing significantly chemical sensitivity towards gaseous benzene. The present work provides a facile and versatile approach for designing the high-performance chemical sensing materials.</p
PHOTOCATALYTIC STRATEGY FOR SUSTAINABLE SYNTHESIS OF THIOESTERS FROM SULFONE REAGENTS OR ELEMENTAL SULFUR
No full textPh.DDOCTOR OF PHILOSOPHY (FOS
DEVELOPMENT OF VUE.JS APPLICATION FOR PECS CARD CREATION AND PRINTOUT
No full textCilj ovog rada je izraditi aplikaciju za jednostavnu izradu, dijeljenje i ispis kolekcija PECS kartica namijenjenih za korištenje u komunikaciji s djecom i osobama koje imaju poteškoće sa standardnim oblicima komunikacije. Postojeći alati za izradu PECS kartica su preskupi, zastarjeli i neintuitivni te je dijeljenje kolekcija preko njih u većini slučajeva nemoguće. Radi toga korisnici tih aplikacija pojedinačno troše previše vremena na izradu kolekcija istih tema, umjesto da koriste postojeće kolekcije i fokusiraju se na izradu novih, jedinstvenih kolekcija. PECS card maker aplikacija bi uz minimalnu obuku trebala omogućiti defektolozima, pedagozima i obrazovnim rehabilitatorima jednostavnu izradu kolekcija, te dijeljenje tih kolekcija s kolegama kroz aplikaciju. Dolaskom na stranicu i jednostavnom registracijom preko Google računa, korisnicima se daje pristup javno objavljenim kolekcijama, te im se pruža mogućnost da sami kreiraju i objave svoje kolekcije, kao i da kopiraju postojeće i prilagode ih svojim potrebama. Administratori web aplikacije kontroliraju sadržaj kolekcija te ovisno o prikladnosti odobravaju ili zabranjuju javno objavljivanje, uz slanje tekstualnog obrazloženja autoru kolekcije. Također, korisnici aplikacije mogu ostavljati komentare na javno dostupne kolekcije, te time bolje informirati druge korisnike aplikacije o njenoj kvaliteti i eventualnim nedostacima.The purpose of this work is to make an application for simple creation, sharing and printing of the PECS card collection, whose purpose is to help in communication with children and adults who are having problems with standard forms of communication. Existing tools for PECS card creation are expensive, obsolete and unintuitive, and sharing collections between them is almost impossible. Because of that, users of those applications are individually spending too much time to make collection which someone has already made, instead of creating something new and unique. PECS card maker application should, with minimal training, enable pedagogues, education rehabilitators and defectologists to simply create PECS collection, as well as share them with their colleagues through the application. Once on the web page, users are registered via the Google account, and given access to publicly available collections. They are also given the tools to create their own collections and publish them, as well as to copy existing collections and adapt them to their needs. Web application administrators control the collections content and, depending on it, approve or deny publishing, while sending a message to the author regarding the reasons for the rejection. User can also leave comment on published collections, which helps inform other users about the quality and potential imperfections of the collection in question
Visible light driven deuteration of formyl C–H and hydridic C(sp3)–H bonds in feedstock chemicals and pharmaceutical molecules
No full text10.1039/d0sc02661aChemical Science11338912-891
Artificial-Intelligence-Enhanced Study on the Optimization of the Responsibility and Compensation Mechanism for Provincial Cultivated Land Retention from a Fairness Perspective
No full textResearch Objectives: Considering the complex challenges arising from urbanization, population growth, and the consequential strain on China’s cultivated land resources, we integrate insights from advanced artificial intelligence (AI) technology. The primary objective is to quantitatively assess the cultivated land-holding responsibility of local governments in China from a fairness perspective. Our aim is to integrate the cultivated land responsibility ownership amount into the compensation mechanism for cultivated land protection, thereby promoting fairness, cultivated land conservation, and sustainable agricultural development across Chinese provinces while ensuring efficient agricultural product distribution. Research Methodology: Beyond a traditional literature review and model analysis, we incorporated AI technology for data analysis and model optimization. Findings: ① The findings demonstrate a surplus in both food security and ecological security within cultivated land. ② In-depth analysis via AI revealed that the provinces with the largest surplus include Heilongjiang, Jilin, and Hubei. ③ With the precision provided by AI, we delineated the minimum value of the cultivated land responsibility ownership amount for each province. Eleven provinces met this criterion, primarily located in the northeast and central regions and including Yunnan in the west. ④ From a fairness perspective, coupled with AI insights, we established a compensation mechanism for cultivated land protection that is better suited to the Chinese context. Based on this mechanism, the national average compensation standard was calculated to be 26,900 CNY per hectare. The highest standards were observed in Shanghai, Beijing, and Jiangsu, while the lowest were in Shanxi, Heilongjiang, and Gansu
Showing the essential science structure of a scientific domain and its evolution
No full textCategory cocitation and its representation through social networks is proving to be a very adequate technique for the visualization and
analysis of great scientific domains. Its combination with pathfinder networks using pruning values r=∞and q=n−1 makes manifest the essence of research in the domain represented, or what we might call the `most salient structure'. The possible loss of structural information, caused by aggressive pruning in peripheral areas of the networks, is overcome by creating heliocentric maps for each category. The depictions obtained with this procedure become tools of great usefulness in view of their capacity to reveal the evolution of a given scientific domain over time, to show differences and similarities between different domains, and to suggest possible new lines for development. This article presents the scientogram of the United States for the year 2002, identifying its essential structure. We also show the scientograms of China for the years 1990 and 2002, in order to study its particular national evolution.
Finally, we try to detect patterns and tendencies in the three scientograms that would allow one to predict or flag the evolution of a scientific domain
La représentation de la machine dans la trilogie d’anticipation scientifique d’Albert Robida : du texte à l’image et de l’image au texte
No full textCette thèse étudie la représentation de la machine chez Robida. La partie centrale de notre recherche s’intéresse à révéler ses significations et interroge sa mise en scène littéraire et visuelle dans chacun des romans de la trilogie d’anticipation scientifique la plus connue de l’auteur-illustrateur. La quête se transforme en un voyage continu entre le lisible et le visible, le dit et le non-dit, la description littéraire et l’imagination, la réalité et la fiction. Nous nous intéressons à l’évolution de la vision de Robida : dans Le Vingtième siècle, l’image de la machine bienfaisante, facilitant la vie de l’homme, économisant du temps et de l’argent, et contribuant largement à son bonheur et à son divertissement, à part quelques accidents très limités, se traduit par une complémentarité avantageuse entre le texte d’une part et les vignettes, les tableaux et les hors-textes se trouvant dans le récit, d’autre part. Celle-ci se transforme, dans La Guerre au vingtième siècle, en une inquiétude vis-à-vis de l’instrumentalisation de la machine pour la guerre, qui s’exprime par une projection de la narration vers l’illustration in-texte, et sensibilise le lecteur en montrant le caractère violent et offensif d’appareils uniquement nommés. Celle-ci devient finalement, dans La Vie électrique, synonyme d’un pessimisme total quant à l’implication de la machine dans la société et à la puissance du savoir scientifique dans l’avenir, qui s’affiche dans des hors-textes sombres et maussades.
Dans ce cadre, la machine illustrée exige une lecture iconotextuelle, une importance accordée au détail, aux éléments présents ou absents, aux modalités de passage d’un mode de présentation à l’autre, à la place anticipée ou tardive de l’illustration, au rapport entre le texte, le dessin et sa légende, aux mots qui migrent vers le dessin et surtout au reste du décor incomplet.
Chez Robida, les louanges qui passent à la critique et l’humour qui se fait cynisme, sont assez représentatifs des espoirs et des craintes suscités par la découverte et la mise en application de l’électricité, par ses vertus, mais aussi par son aspect incontrôlable.This thesis focuses on the presentation of the machine by Robida. The major part of our research aims to reveal its meanings and examines its literary and visual settlement in each novel in the most popular trilogy of scientific anticipation made by the author. The search has the aspect of a continuous travel between what is read and what is seen, the said and the unsaid, the literary description and the imagination, the reality and the fiction. We will be mainly interested by the evolution of Albert Robida’s vision: in Le Vingtième siècle, the image of a beneficial machine, simplifying every day’s life, saving time and money and largely contributing to the happiness and the entertainment of every man’s kind, except some occasional accidents, is reflected by a close and helpful connection between the text, the vignette and the inserts. This image is modified, in La Guerre au vingtième siècle, into an anxiety felt towards the use of the machine as a war weapon, and expressed in the transfer of the narration to the illustration in-texte, aiming to touch the reader and make him aware of the violent and brutal aspect of the machines that are only named. This image causes, in La Vie électrique, a serious pessimistic vision of the use of the machine in the society and the power of the scientific knowledge in the future which is displayed in dark and gloomy hors-texte.
In this context, the illustrated machine requires a double reading, details oriented and interested in the presence and the absence of elements, in the transfer between the text and the illustration, in the anticipated or the belated picture, in the relationship between the text, the image and the caption, in the words that have been transferred to the image and mostly the rest of the incomplete picture.
In Robida’s work, the praises that become a criticism and the satire being cynicism, are very representatives of the hopes and the fears created by the discovery and the application of the electricity, by its virtues, but also its uncontrollable aspect
La représentation de la machine dans la trilogie d’anticipation scientifique d’Albert Robida : du texte à l’image et de l’image au texte
No full textCette thèse étudie la représentation de la machine chez Robida. La partie centrale de notre recherche s’intéresse à révéler ses significations et interroge sa mise en scène littéraire et visuelle dans chacun des romans de la trilogie d’anticipation scientifique la plus connue de l’auteur-illustrateur. La quête se transforme en un voyage continu entre le lisible et le visible, le dit et le non-dit, la description littéraire et l’imagination, la réalité et la fiction. Nous nous intéressons à l’évolution de la vision de Robida : dans Le Vingtième siècle, l’image de la machine bienfaisante, facilitant la vie de l’homme, économisant du temps et de l’argent, et contribuant largement à son bonheur et à son divertissement, à part quelques accidents très limités, se traduit par une complémentarité avantageuse entre le texte d’une part et les vignettes, les tableaux et les hors-textes se trouvant dans le récit, d’autre part. Celle-ci se transforme, dans La Guerre au vingtième siècle, en une inquiétude vis-à-vis de l’instrumentalisation de la machine pour la guerre, qui s’exprime par une projection de la narration vers l’illustration in-texte, et sensibilise le lecteur en montrant le caractère violent et offensif d’appareils uniquement nommés. Celle-ci devient finalement, dans La Vie électrique, synonyme d’un pessimisme total quant à l’implication de la machine dans la société et à la puissance du savoir scientifique dans l’avenir, qui s’affiche dans des hors-textes sombres et maussades.
Dans ce cadre, la machine illustrée exige une lecture iconotextuelle, une importance accordée au détail, aux éléments présents ou absents, aux modalités de passage d’un mode de présentation à l’autre, à la place anticipée ou tardive de l’illustration, au rapport entre le texte, le dessin et sa légende, aux mots qui migrent vers le dessin et surtout au reste du décor incomplet.
Chez Robida, les louanges qui passent à la critique et l’humour qui se fait cynisme, sont assez représentatifs des espoirs et des craintes suscités par la découverte et la mise en application de l’électricité, par ses vertus, mais aussi par son aspect incontrôlable.This thesis focuses on the presentation of the machine by Robida. The major part of our research aims to reveal its meanings and examines its literary and visual settlement in each novel in the most popular trilogy of scientific anticipation made by the author. The search has the aspect of a continuous travel between what is read and what is seen, the said and the unsaid, the literary description and the imagination, the reality and the fiction. We will be mainly interested by the evolution of Albert Robida’s vision: in Le Vingtième siècle, the image of a beneficial machine, simplifying every day’s life, saving time and money and largely contributing to the happiness and the entertainment of every man’s kind, except some occasional accidents, is reflected by a close and helpful connection between the text, the vignette and the inserts. This image is modified, in La Guerre au vingtième siècle, into an anxiety felt towards the use of the machine as a war weapon, and expressed in the transfer of the narration to the illustration in-texte, aiming to touch the reader and make him aware of the violent and brutal aspect of the machines that are only named. This image causes, in La Vie électrique, a serious pessimistic vision of the use of the machine in the society and the power of the scientific knowledge in the future which is displayed in dark and gloomy hors-texte.
In this context, the illustrated machine requires a double reading, details oriented and interested in the presence and the absence of elements, in the transfer between the text and the illustration, in the anticipated or the belated picture, in the relationship between the text, the image and the caption, in the words that have been transferred to the image and mostly the rest of the incomplete picture.
In Robida’s work, the praises that become a criticism and the satire being cynicism, are very representatives of the hopes and the fears created by the discovery and the application of the electricity, by its virtues, but also its uncontrollable aspect
Caracterização e aplicação de catalisadores sólidos a base de titanato de alumínio dopado com érbio na hidrólise de ésteres de fosfato
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2014.Neste trabalho foram estudadas as propriedades físico-químicas de suportes sólidos em escala nanométrica, a base de óxidos mistos de alumina e dióxido de titânio, como é o caso do titanato de alumínio (Al2TiO5). A influência da deposição de Er0 na superfície desses suportes e a atuação deste tipo de material na catálise heterogênea de ésteres de fosfato também foram estudadas. A composição dos catalisadores obtidos foi avaliada a partir do método quali-quantitativo de espectrometria de fluorescência de raios-x por energia dispersiva (EDXRFS), no qual as amostras analisadas foram homogeneizadas através da fusão de seus compostos e transformadas em novos matérias geralmente denominados pérolas ou discos de vidro. A partir dessa técnica foi possível obter-se a análise semi-quantitativa e quantitativa dos compostos em estudo, e através dessa análise foi possível avaliar a composição elementar dos catalisadores. Para caracterizar cada catalisador, foram realizados estudos da morfologia e estrutura cristalina dos materiais a partir de técnicas microscópicas (SEM) e difração de raios-x (XRD), análise da área superficial (BET), volume e tamanho dos poros (BJH) por adsorção física de nitrogênio. Os catalisadores foram aplicados na degradação do Paraoxon Metílico (DMPNPP) e os resultados obtidos mostraram elevada atividade dos catalisadores utilizados.Abstract : This present work reports the study of the physicochemical properties of nanoscale solid supports, obtained by the mix of alumina and titanium dioxide, such as aluminum titanate (Al2TiO5). The influence of the deposition of Er0 on the surface of such supports and the performance of this type of material in heterogeneous catalysis of phosphate esters were also studied. The composition of the catalysts obtained was evaluated using a quali-quantitative method better known as X-Ray Fluorescence Spectrometry by Dispersive Energy (EDXRFS), in which the analyzed samples were homogenized by merging its compounds and turned into a new material usually called beads or glass discs. Based on this technique it was possible to ensure a semi-quantitative and a quantitative analysis of the compounds, and through this analysis it was possible to evaluate the elemental composition of the catalysts. To characterize each catalyst, studies of the morphology and crystalline structure of the materials were performed by microscopic techniques (SEM) and X-ray diffraction (XRD) analysis of size surface area (BET) and pore volume (BJH) by nitrogen adsorption. The catalysts were applied in the degradation of Paraoxon (DMPNPP) and the results showed high activity of the catalysts used
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