975 resultados para electrophilic substitution


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Com a resultat de les politiques i estratègies de col·laboració entre la universitat de Vic i de l’hospital i de la voluntat de realitzar activitats formatives conjuntes , s’estableix un línia de treball orientada a l’estudi i anàlisi de la situació logística interna actual del laboratori d’anàlisis clíniques de l’Hospital General de Vic. El treball es centra en el procés intern del laboratori i l’abast de l’estudi es troba limitat a les àrees especifiques d’hematologia i coagulació i bioquí… [+]mica. D’aquestes dues àrees el treball realitza un estudi exhaustiu del seu procés intern, identifica les seves activitats i la seva metodologia de treball amb l’objectiu d’elaborar el Value Stream Map de cadascuna de les àrees. Les àrees de Microbiologia, Banc de Sang i Urgències resten fora d’aquest estudi exhaustiu tot i que són presents en el treball per la inevitable interacció que tenen en la globalitat del procés. El treball es centra bàsicament en els processos automatitzats tot i que els processos que es duen a terme en el laboratori són tant automatitzats com manuals. També es limita al sistema productiu intern del laboratori tot i la interacció que té aquest sistema intern amb altres centres productius del sistema com ara són els centres d’atenció primària, els diversos hospitals i centres d’atenció sociosanitària. El laboratori es troba immers en el moment de l’elaboració d’aquest treball en un situació de canvi i millora del seus processos interns que consisteixen principalment en la substitució de part la maquinària actual que obliguen a la definició d’un nou layout i d’una nova distribució de la producció a cada màquina. A nivell extern també s’estan produint millores en el sistema informàtic de gestió que afecten a part del seu procés. L’objectiu del treball és donar visibilitat total al procés de logística interna actual del laboratori, identificant clarament com són i quina seqüència tenen els processos logístics interns i els mètodes de treball actuals, tant de recursos màquina com recursos persona, per poder identificar sota una perspectiva de generació de valor, aquells punts concrets de la logística interna que poden ser millorats en quant a eficiència i productivitat amb l’objectiu que un cop identificats es puguin emprendre accions i/o projectes de millora. El treball finalitza amb un anàlisis final del procés logística interna des d’una òptica Lean. Per fer-ho, identifica aquelles activitats que no aporten valor al procés o MUDA i les classifica en set categories i es realitzen diverses propostes de millora com són la implantació d’un flux continu , anivellat i basat en un concepte pull , identifica activitats que poden ser estandarditzades i/o simplificades i proposa modificacions en les infraestructures físiques per donar major visibilitat al procés. L’aspecte humà del procés es planteja des d’un punt de vist de metodologia, formació, comunicació i aplicació de les 5S.

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Marine mammals are exposed to persistent organic pollutants (POPs), which may be biotransformed to metabolites some of which are highly toxic. Both POPs and their metabolites may lead to adverse health effects, which have been studied using various biomarkers. Changes in endocrine homeostasis have been suggested to be sensitive biomarkers for contaminant-related effects. The overall objective of this doctoral thesis was to investigate biotransformation capacity of POPs and their potential endocrine disruptive effects in two contrasting ringed seal populations from the low contaminated Svalbard area and from the highly contaminated Baltic Sea. Biotransformation capacity was studied by determining the relationships between congener-specific patterns and concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs) and their hydroxyl (OH)- and/or methylsulfonyl (MeSO2)-metabolites, and catalytic activities of hepatic xenobiotic-metabolizing phase I and II enzymes. The results suggest that the biotransformation of PCBs, PBDEs and toxaphenes in ringed seals depends on the congener-specific halogen-substitution pattern. Biotransformation products detected in the seals included OH-PCBs, MeSO2-PCBs and –DDE, pentachlorophenol, 4-OHheptachlorostyrene, and to a minor extent OH-PBDEs. The effects of life history state (moulting and fasting) on contaminant status and potential biomarkers for endocrine disruption, including hormone and vitamin homeostasis, were investigated in the low contaminated ringed seal population from Svalbard. Moulting/fasting status strongly affected thyroid, vitamin A and calcitriol homeostasis, body condition and concentrations of POPs and their OH-metabolites. In contrast, moulting/fasting status was not associated with variations in vitamin E levels. Endocrine disruptive effects on multiple endpoints were investigated in the two contrasting ringed seal populations. The results suggest that thyroid, vitamin A and calcitriol homeostasis may be affected by the exposure of contaminants and/or their metabolites in the Baltic ringed seals. Complex and non-linear relationships were observed between the contaminant levels and the endocrine variables. Positive relationships between circulating free and total thyroid hormone concentration ratios and OH-PCBs suggest that OH-PCBs may mediate the disruption of thyroid hormone transport in plasma. Species differences in thyroid and bone-related effects of contaminants were studied in ringed and grey seals from low contaminated references areas and from the highly contaminated Baltic Sea. The results indicate that these two species living at the same environment approximately at the same trophic level respond in a very different way to contaminant exposure. The results of this thesis suggest that the health status of the Baltic ringed seals has still improved during the last decade. PCB and DDE levels have decreased in these seals and the contaminant-related effects are different today than a decade ago. The health of the Baltic ringed seals is still suggested to be affected by the contaminant exposure. At the present level of the contaminant exposure the Baltic ringed seals seem to be at a zone where their body is able to compensate for the contaminant-mediated endocrine disruption. Based on the results of this thesis, several recommendations that could be applied on monitoring and assessing risk for contaminant effects are provided. Circulating OH-metabolites should be included in monitoring and risk assessment programs due to their high toxic potential. It should be noted that endogenous variables may have complex and highly variable responses to contaminant exposure including non-linear responses. These relationships may be further confounded by life history status. Therefore, it is highly recommended that when using variables related to endocrine homeostasis to investigate/monitor or assess the risk of contaminant effects in seals, the life history status of the animal should be carefully taken into consideration. This applies especially when using thyroid, vitamin A or calcitriolrelated parameters during moulting/fasting period. Extrapolations between species for assessing risk for contaminant effects in phocid seals should be avoided.

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The reaction of ten cis-octalins and cis-octalones with thallium trinitrate (TTN) leads to different products, depending mainly on the substitution pattern of the substrate. Functionalized cis-hydrindanes were obtained from the reaction of 1,2,3,4,4a,5,8,8a-octahydro-4a-methylnaphthalene and of 1,2,3,4,4a,5,8,8a-octahydro-4a,7-dimethylnaphthalene with TTN in acetonitrile, whereas a cyclic ether was formed treating 1,2,3,4,4a,5,8,8a-octahydro-6,8a-dimethylnaphthalen-1-ol with TTN in trimethylorthoformate (TMOF).

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Reduction of five substituted octalones employing lithium tri-sec-butylborohydride (L-selectride®) in THF and ethyl ether led to allylic alcohols with moderate diastereoselectivity. The stereoselectivity of addition of bulky hydrides showed to be different from most examples in the literature and was strongly influenced by substitution on the octalone ring.

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Basic concepts that play an important role in some organic reactions are revisited in this paper, which reports a pedagogical experience involving undergraduate and graduate students. A systematic procedure has been applied in order to use widespread available computational tools. This paper aims to discuss the use of computers in teaching electrophilic addition reactions to alkenes. Two classical examples have been investigated: addition to non-conjugated alkenes and addition to conjugated dienes. The results were compared with those normally discussed in organic textbooks. Several important concepts, such as conformational analysis and energy control (kinetic and thermodynamic) involved in reaction mechanisms can be taught more efficiently if one connects theoretical and practical tools.

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The HERC gene family encodes proteins with two characteristic domains: HECT and RCC1-like. Proteins with HECT domain shave been described to function as ubiquitin ligases, and those that contain RCC1-like domains have been reported to function as GTPases regulators. These two activities are essential in a number of important cellular processes such as cell cycle, cell signaling, and membrane trafficking. Mutations affecting these domains have been found associated with retinitis pigmentosa, amyotrophic lateral sclerosis, and cancer. In humans, six HERC genes have been reported which encode two subgroups of HERC proteins: large (HERC1-2) and small (HERC3-6). The giant HERC1 protein was the first to be identified. It has been involved in membrane trafficking and cell proliferation/growth through its interactions with clathrin, M2-pyruvate kinase, and TSC2 proteins. Mutations affecting other members of the HERC family have been found to be associated with sterility and growth retardation. Here, we report the characterization of a recessive mutation named tambaleante, which causes progressive Purkinje cell degeneration leading to severe ataxia with reduced growth and lifespan in homozygous mice aged over two months. We mapped this mutation in mouse chromosome 9 and then performed positional cloning. We found a GuA transition at position 1448, causing a Gly to Glu substitution (Gly483Glu) in the highly conserved N- terminal RCC1-like domain of the HERC1 protein. Successful transgenic rescue, with either a mouse BAC containing the normal copy of Herc1 or with the human HERC1 cDNA, validated our findings. Histological and biochemical studies revealed extensive autophagy associated with an increase of the mutant protein level and a decrease of mTOR activity. Our observations concerning this first mutation in the Herc1 gene contribute to the functional annotation of the encoded E3 ubiquitin ligase and underline the crucial and unexpected role of this protein in Purkinje cell physiology.

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On a laboratory scale effluents were produced from bichromic dyeing of acrylic fabrics with the basic dyes Blue Astrazon FGGL 300% and Yellow Gold Astrazon GL 200%. The residual dyeing baths were subjected to a photoelectrochemical treatment and reused in a second dyeing process. In the reutilization study, dyeings with treated effluent were compared with standard dyeings with distilled water. The results of dyeings using 100% of treated effluent were unsatisfactory, but the substitution of 10 to 30% of the treated effluent by distilled water resulted in reduced and more acceptable values for difference in colour intensity (ΔE) between 1.86 and 0.3.

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Preparation of the title compounds are described as an alternative nucleophilic aromatic substitution for practices in the graduate laboratory. The low toxicity and disponibility of the reagents make a suitable procedure approach to experiments regarding this aromatic reaction.

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The NMR (RMN¹H, 13C, COSY, HMQC, HMBC, NOE-DIFF, NOESY) and mass spectra data analysis of sixteen flavonoids, including nine natural, 7-O-methylkanferol (ramnocitrin), 3,7-di-O-methylkanferol (kumatakenin), 3-O-methylquercetin, 3,7,3',4'-tetra-O-methylquercetin (retusin), 3,7,8,4'-tetra-O-methylgossipetin, 3,7,8,3',4'-penta-O-methylgossipetin, 7-O-methylapigenin (genkwanin), 3,7,8-tri-O-methylherbacetin, 7,4'- di-O-methylquercetin (ombuine), isolated from Solanum paludosum and S. jabrense, and seven prepared methyl and acetyl derivatives, are discussed according the substitution on the rings A, B and C.

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In this work, the perovskite-type oxides LaNiO3, LaMnO3, La0,7Sr0,3NiO3 and La0,7Sr0,3MnO3 were prepared by co-precipitation and tested in the NO reduction with CO at 400 and 500 ºC for 10 h. The catalysts were characterized by X-ray diffraction, temperature programmed reduction with hydrogen, nitrogen adsorption and chemical analysis. The nonstoichiometric oxygen was quantified by temperature programmed reduction, and the catalytic tests showed that the La0,7Sr0,3MnO3 catalyst presented the higher performance for the reduction reaction of NO with CO. The partial substitution of lanthanum by strontium increased the NO conversion and the N2 yield.

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Static electric dipole polarizabilities and first hyperpolarizabilites have been calculated for the title molecules and their 3' and 4'-nitro derivatives at ab-initio Hartree- Fock/6-31G(d, p) level. The influence of the pivotal p vacant 3A elements (B, Al or Ga) substitution on the electrical properties of these molecules is detailed. The axial vector components of the first hyperpolarizabilities β(0) of the push-pull 4'-nitro derivatives, -18.2×10-32 esu (B), -21.1×10-32 esu (Al) and -20.8×10-32 esu (Ga) are calculated to be as much as fourfold larger then that calculated for the p-nitroaniline, a reference organic molecule for comparison for this type of molecular property.

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Oxocarbons ions are cyclic compounds presenting unusual electronic and vibrational properties. These molecules anions possess a high symmetry and degree of electronic delocalization, characteristics that have been discussed in several structural and spectroscopic investigations. Compounds in which one or more of the carbonyl oxygen atoms are replaced by other atoms or groups are called pseudo-oxocarbons. Compounds formed by substitution of the carbonyl groups by nitrogen groups former a new class named squaraines. Specificity the dicyanomethylene groups are interesting because of the possibility of further extension of the electronic delocalization and a new coordination site. These molecules also present interesting coordination properties which make these systems potentially useful in crystal engineering research.

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In this paper we gathered articles concerning insertion reactions of arynes, exclusively generated from 2-(trimethylsilyl)aryl triflates in the presence of fluoride ions, in substrates bearing nucleophilic and electrophilic portions separated by sigma bonds. Accordingly, we stand out the great importance and versatility of such transformations in the preparation of highly functionalized aromatic systems, which are hardly synthesized in just one step for other methods.

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Pyrazinoic acid esters have been synthesized as prodrugs of pyrazinoic acid. In the literature, its preparation is reported through the reaction of pyrazinoyl chloride with alcohols and the reaction with DCC/DMAP. In this work, it is reported a 2² factorial design to evaluate the preparation of these esters through the substitution of alkyl bromides with carboxylate anion. The controlled factors were alkyl chain length of bromides (ethyl and hexyl) and the used base (triethylamine and DBU). Results revealed that the used base used has significant effect on yield, and alkyl bromide used has neither significant influence, nor its interaction effect with base.

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Soil organic matter is the main sorptive soil compartment for atrazine in soils, followed in a minor scale by the inorganic fraction. In this study, the soil organic matter quality and atrazine sorption were investigated in four different soil types. The pedogenic environment affected the humification and therefore the chemical composition of the organic matter. The organic matter contribution to atrazine sorption was larger (60-83%) than that of the inorganic fraction. The organic matter capacity in retaining the herbicide was favoured by a higher decomposition degree and a smaller carboxylic substitution of the aliphatic chains.