Nuovi Complessi Carbossilati di Rutenio Contenenti Difosfine Elettron-ricche per la sintesi di Molecole di Interesse Alimentare e Biologico

The aim of this thesis was the synthesis of novel catalytic systems based on acetate ruthenium complexes, bearing basic and relatively bulky diphosphines and their application in the reduction of carbonyl substrates to their corresponding alcohols, with molecular hydrogen and via transfer hydrogenation reaction using 2-propanol as hydrogen source. Moreover, the employment of these systems as catalysts in the alkylation of aliphatic and aromatic amines with primary alcohols and diols via borrowing hydrogen was studied. In addition. The work performed on this subject can be split out into four parts as follows: 1. The first part has concerned the synthesis and the characterization of the complexes Ru(OAc)2(PP) [PP=1,1\u2019-bis(diisopropylphosphino)ferrocene; 1,1\u2019-bis(dicyclohexylphosphino)ferrocene), Ru(OAc)2(PP)(NN) (NN= 2-(aminomethyl)pyridine; ethylenediamine)and the monocarbonyl derivatives Ru(OAc)2(CO)(PP). 2. The second part has been focused on the study on the catalytic performances of Ru(OAc)2(PP) and in situ generated Ru(OAc)2(PP)(NN) in the transfer hydrogenation of carbonyl compounds in basic 2-propanol 3. During the third part the unprecedented hydrogenation of benzaldehyde in neat conditions (solvent-less) catalyzed by Ru(OAc)2(CO)(PP) with hydrogen at low and high pressure, has been studied, affording benzyl alcohol with high purity. The scope of this reaction has been extended to different aromatic and \u3b1,\u3b2-unsaturated aldehydes, with high chemoselectivity for the C=O vs. C=C bond, and to ketone and imine substrates, under basic and also acidic conditions at very high S/C (105). In particular, trans-cinnamaldehyde, citral have been reduced to the corresponding food relevant alcohols. 4. The final part has regarded the application of the new developed Ru(OAc)2(CO)(PP) systems in the ethylation of N-ethylcyclohexylamine with ethanol via borrowing hydrogen at relatively mild conditions (30 - 100 \ub0C). To broaden the scope of this transformation, primary aliphatic and aromatic amines and different alkylating agents, including diols allowing formation of substituted pyrrolidines and piperazines, have been employed. Intramolecular reaction of 2-hydroxyethylaniline has also been investigated to obtain indoles, which as the pyrrolidine and piperazine derivatives are biologically relevant pharma frameworks. The wide reactivity and productivity exhibited by these new class of ruthenium catalysts make them very attractive for industrial applications

The Seiberg-Witten map for non-commutative pure gravity and vacuum Maxwell theory

In this paper the Seiberg-Witten map is first analyzed for non-commutative Yang-Mills theories with the related methods, developed in the literature, for its explicit construction, that hold for any gauge group. These are exploited to write down the second-order Seiberg-Witten map for pure gravity with a constant non-commutativity tensor. In the analysis of pure gravity when the classical space-time solves the vacuum Einstein equations, we find for three distinct vacuum solutions that the corresponding non-commutative field equations do not have solution to first order in non-commutativity, when the Seiberg-Witten map is eventually inserted. In the attempt of understanding whether or not this is a peculiar property of gravity, in the second part of the paper, the Seiberg-Witten map is considered in the simpler case of Maxwell theory in vacuum in the absence of charges and currents. Once more, no obvious solution of the non-commutative field equations is found, unless the electromagnetic potential depends in a very special way on the wave vector.Comment: Misprints corrected. References adde

Highly Efficient Hydrogenation Ruthenium and Osmium Catalysts based on Ampy type Ligands

Ruthenium phosphine complexes have been widely examined in homogeneous hydrogenation (HY) and transfer hydrogenation reactions (TH), which are cost-effective and environmentally benign ways accepted in the industry for the reduction of carbonyl compounds. On account of the reversibility of the C-H bond activation, ruthenium catalysts have attracted a great deal of interest for a number of organic transformations, including borrowing hydrogen reactions. In this context, the design of efficient chelating and non-innocent ligands is crucial to achieve high activity and retard catalyst deactivation. Highly efficient Ru and Os catalysts for both TH and HY reactions were obtained by our group with ligands based on the 2-(aminomethyl)pyridine motif (A). More productive catalysts were subsequently developed by employment of pincer terdentate CNN ligands showing a metal-carbon \u3c3-bond (B).1 These complexes allow fast reduction of ketones and aldehydes, including some biomass derivatives (5-HMF, ethyl levulinate), with H2, 2-propanol or ammonium formate at S/C up to 105. Employment of chiral catalysts in the ketone reduction afforded alcohols with up to 99% ee. The Ru and Os derivatives A and B can also catalyze the acceptorless DHY of alcohols to ketones and other transformations involving alcohol C-H activation, namely alcohol racemization, deuteration and ketone \u3b1-alkylation. Evidence has been provided that the catalytically active Ru hydride species are in rapid equilibrium with metal-amino alkoxides

2.5D Chiplet Architecture for Embedded Processing of High Velocity Streaming Data

This dissertation presents an energy efficient 2.5D chiplet-based architecture for real-time probabilistic processing of high-velocity sensor data, from an autonomous real-time ubiquitous surveillance imaging system. This work addresses problems at all levels of description. At the lowest physical level, new standard cell libraries have been developed for ultra-low voltage CMOS synthesis, as well as custom SRAM memory blocks, and mixed-signal physical true random number generators based on the perturbation of Sigma-Delta structures using random telegraph noise (RTN) in single transistor devices. At the chip level architecture, an innovative compact buffer-less switched circuit mesh network on chip (NoC) capable of reaching very high throughput (1.6Tbps), finite packet delay delivery, free from packet dropping, and free from dead-locks and live-locks, was designed for this chiplet-based solution. Additionally, a second NoC connecting processors in the network, was implemented based on token-rings, allowing access to external DDR memory. Furthermore, a new clock tree distribution network, and a wide bandwidth DRAM physical interface have been designed to address the data flow requirements within and across chiplets. At the algorithm and representation levels, the Online Change Point Detection (CPD) algorithm has been implemented for on-line learning of background-foreground segmentation. Instead of using traditional binary representation of numbers, this architecture relies on unconventional processing of signals using a bio-inspired (spike-based) unary representation of numbers, where these numbers are represented in a stochastic stream of Bernoulli random variables. By using this representation, probabilistic algorithms can be executed in a native architecture with precision on demand, where if more accuracy is required, more computational time and power can be allocated. The SoC chiplet architecture has been extensively simulated and validated using state of the art CAD methodology, and has been submitted to fabrication in a dedicated 55nm GF CMOS technology wafer run. Experimental results from fabricated test chips in the same technology are also presented

Users Perceptions of Headphones and Earbuds in Norway and Brazil: An Empirical Study Based on a Kahoot Quiz

Abstract. Headphones and earbuds are seemingly more popular than ever with the wide availability of smartphones and music streaming services. Such personal audio systems are also essential for many blind and visually impaired computer users that relies on text-to-speech. Few published studies address the users’ perceptions of such personal audio output devices. However, past research shows that negative perceptions may lead to device abandonment. General-purpose equipment may therefore be more successful than special purpose assistive technologies for marginalized groups. We therefore set out to gain insight into how users generally perceive headphones and earbuds, and we wanted to base our study in two different cultural contexts. A questionnaire built on a Kahoot quiz was developed involving 12 questions related to headphones and earbuds. A total of 100 participants were recruited in Norway and Brazil. The results show that intuitiveness is the most valued feature of these devices and cost was not. Brazilians expressed skepticism regarding the use of headphones while walking and when travelling on public transport, while Norwegians expressed that headphones were safe to use in such situations. Our experiences showed that Kahoot is a promising platform for conducting such experiments, as it may appear more engaging than regular questionnaires. Moreover, they are relatively easy to set up and allow response times to be measuredacceptedVersio

Pincer and Carbonyl Ruthenium Complexes for Transfer Hydrogenation Reactions

The transfer hydrogenation (TH) catalyzed by ruthenium complexes is a cost-effective and environmentally benign way for the reduction of carbonyl compounds. On account of the reversibility of the TH process, ruthenium catalysts have attracted a great deal of interest for a number of C-H activation organic transformations. To improve the catalytic activity and to retard decomposition, the design of suitable chelating and non-innocent ligands appears crucial. We report here the preparation of pincer, carbonyl and acetate ruthenium complexes, displaying high productivity for the TH of carbonyl compounds, including flavanones and biomass-derived molecules (5-HMF, ethyl levulinate). The alkylation of amines with alcohols and the preliminary results on the photochemical TH of carbonyl compounds are also presented

Germanium-on-silicon Waveguides for Mid-infrared Photonic Sensing Chips

Germanium-on-silicon rib waveguides are modelled, fabricated and characterized with a novel near-field infrared spectroscopy technique that allows on-chip investigation of the waveguide losses at 5.8 μm wavelength

MATURAÇÃO DE SEMENTES DE Inga ureguensis HOOK. ET ARN. EM FLORESTA RIPÁRIA DO RIO MOJI GUAÇU, MUNICIPIO DE MOJI GUAÇU, SP

Visando fornecer subsídios para a utilização e manejo de Inga utuguensis Hook. et Arn., foi estudada a fenologia da maturação das sementes em uma população natural localizada em floresta rípáría, à margem direita do rio Moji Guaçu, município de Moji Guaçu-SP. As observações feno lógicas, realizadas no período de agosto de 1990 a fevereiro de 1992, revelam que 1. utuguensis concentrou a floração e frutífícação num único período do ano, durante a estação chuvosa, respectivamente nos meses setembro/outubro e outubro/novembro. As sementes atingiram a maturidade fisiológica, apresentando valores máximos de vigor e poder germinativo aos 142 e 132 dias após o florescimento, respectivamente, no 1° ano e 2° ano de estudo. A análise química das sementes revelou não haver alterações flagrantes na composição, porém o contendo de carboidratos totais da polpa teve um aumento considerável no decorrer do processo de maturação. Durante as observações de campo verificou-se predação dos frutos por macacos e aves, da ordem de 65,61% em 1991 e 44,78% em 1992

ECOFISIOLOGIA DE SEMENTES DE Inga uruguensis Hook. et Arn. EM CONDIÇOES DE LABORATÓRIO

Os estudos ecofisiológicos em sementes de Inga uruguensis mostraram que as sementes germinam satisfatoriamente nos gradientes de umidade encharcado (80,65%), muito úmido (76,92%), úmido (66,67%) e pouco úmido (50%), nos regimes de temperatura constante de 25ºC e alternada de 20-35°C, tanto na presença quanto ausência de luz. No entanto, as plãntulas sob re­ gime de ausência de luz apresentaram maior índi­ ce de anormalidade, quando comparadas com as plãntulas sob condições de luz, conferindo supe­ rioridade estatística em relação à germinação para o tratamento com luz (72,50%) quando compara­ do à ausência de luz (60,25%). Todos os níveis de umidade e temperaturas testadas apresentaram similaridade estatística para os dados de germina­ ção. Apesar disso, no tocante à umidade, os maiores percentuais médios de germinação foram obtidos em substrato úmido (74%) e pouco úmi­ do (70,5%), seguido de muito úmido (61,5%) e encharcado (59,5%); a temperatura de 25ºC apresentou 68,50% e a de 20-35°C, 64,25% de germi­ nação. Observou-se número elevado de plântulas anormais nos substratos muito úmido e encharca­ do, para todos os regimes de temperatura e luz estudados

DISPERSÃO DE SEMENTES DE Inga uruguensis Hook. et Arn. EM FLORESTA RIPÁRIA DO RIO MOJI GUAÇU, MUNICÍPIO DE MOJI GUAÇU - SP

A dispersão de sementes de Inga uruguensis Hook. et Arn. foi estudada em uma população natural localizada em floresta ripária, do Rio Moji Guaçu, Município de Moji Guaçu, SP, durante o mês de agosto de 1991. O processo de dispersão foi avaliado indiretamente pela análise da distribuição da regeneração natural, através de transectos na direção dos quatro pontos cardeais, a partir de 3 árvores adultas, sendo uma na borda e uma no meio da mata e uma próximo à margem do rio. As plântulas (até 0,20 m de altura) e plantas jovens (de 0,21 a 1,00 m de altura), distantes até 2,00 m de cada lado dos respectivos eixos, foram contadas e medidas. Os resultados mostraram que, para a área de estudo, I. uruguensis apresenta maior densidade de plântulas próximo às árvores (92 plantas aos 10 metros, 30 plantas aos 40 metros e 1 planta aos 90 metros), com maior taxa de recrutamento à medida que se distancia das árvores matrizes. A árvore localizada no meio da mata apresentou maior regeneração (59 plântulas e 32 plantas) até a distância de 150 metros da árvore matriz seguido da próximo à borda (62 -20 plântulas e 42 plantas). A árvore localizada próximo à margem do rio apresentou menor taxa de regeneração de plântulas (18) e de planta (31). Durante as observações de campo verificou-se que macacos e aves ingeriram as sementes, atuando mais como agentes predadores e, eventualmente, como dispersares em potencial. Os principais visitantes observados foram aves da família Psittacidae, como tuim (Forbus xanthopterigiusy e maritaca-verde (Pionus maximiliam), sendo esta a mais freqüente, e macaco- sauá (Callicebus personatus). Verificou-se, também, frutos sendo transportados pela correnteza do rio, o que contribui para aumentar a chance de dispersão da espécie