891 resultados para Viceroyalty of New Granada
Resumo:
With the business environments no longer confined to geographical borders, the new wave of digital technologies has given organizations an enormous opportunity to bring together their distributed workforce and develop the ability to work together despite being apart (Prasad & Akhilesh, 2002). resupposing creativity to be a social process, the way that this phenomenon occurs when the configuration of the team is substantially modified will be questioned. Very little is known about the impact of interpersonal relationships in the creativity (Kurtzberg & Amabile, 2001). In order to analyse the ways in which the creative process may be developed, we ought to be taken into consideration the fact that participants are dealing with a quite an atypical situation. Firstly, in these cases socialization takes place amongst individuals belonging to a geographically dispersed workplace, where interpersonal relationships are mediated by the computer, and where trust must be developed among persons who have never met one another. Participants not only have multiple addresses and locations, but above all different nationalities, and different cultures, attitudes, thoughts, and working patterns, and languages. Therefore, the central research question of this thesis is as follows: “How does the creative process unfold in globally distributed teams?” With a qualitative approach, we used the case study of the Business Unit of Volvo 3P, an arm of Volvo Group. Throughout this research, we interviewed seven teams engaged in the development of a new product in the chassis and cab areas, for the brands Volvo and Renault Trucks, teams that were geographically distributed in Brazil, Sweden, France and India. Our research suggests that corporate values, alongside with intrinsic motivation and task which lay down the necessary foundations for the development of the creative process in GDT.
Resumo:
We report the synthesis and application of some ion-tagged catalysts in organometallic catalysis and organocatalysis. With the installation of an ionic group on the backbone of a known catalyst, two main effects are generally obtained. i) a modification of the solubility of the catalyst: if judicious choice of the ion pair is made, the ion-tag can confer to the catalyst a solubility profile suitable for catalyst recycling. ii) the ionic group can play a non-innocent role in the process considered: if stabilizing interaction between the ionic group and the developing charges in the transition state are established, the reaction can speed up. We describe the use of ion-tagged diphenylprolinol as Zn ligand. The chiral ligand grafted onto an ionic liquid (IL) was recycled 10 times with no loss of reactivity and selectivity, when it was employed in the first example of enantioselective addition of ZnEt2 to aldehydes in ILs. An ammonium-tagged phosphine displayed the capability to stabilize Pd catalysts for the Suzuki reaction in ILs. The ionic phase was recycled 6 times with no detectable loss of activity and very low Pd leaching in the organic phase. This catalytic system was also employed for the functionalization of the challenging substrate 5,11-dibromotetracene. In the field of organocatalysis, we prepared two ion-tagged derivatives of the McMillan imidazolidinone. The results of the asymmetric Diels-Alder reaction between trans-cinnamaldehyde and cyclopentadiene exhibited great dependence on the position and nature of the ionic group. Finally, when O-TMS-diphenylprolinol was tagged with an imidazolium ion, exploiting a silyl ether linker, an efficient catalyst for the asymmetric addition of aldehydes to nitroolefins was achieved. The catalyst displayed enhanced reactivity and the same high level of selectivity of the untagged parent catalyst and it could be employed in a wide range of reaction conditions, included use of water as solvent.
Resumo:
Supramolecular chemistry is a multidisciplinary field which impinges on other disciplines, focusing on the systems made up of a discrete number of assembled molecular subunits. The forces responsible for the spatial organization are intermolecular reversible interactions. The supramolecular architectures I was interested in are Rotaxanes, mechanically-interlocked architectures consisting of a "dumbbell shaped molecule", threaded through a "macrocycle" where the stoppers at the end of the dumbbell prevent disassociation of components and catenanes, two or more interlocked macrocycles which cannot be separated without breaking the covalent bonds. The aim is to introduce one or more paramagnetic units to use the ESR spectroscopy to investigate complexation properties of these systems cause this technique works in the same time scale of supramolecular assemblies. Chapter 1 underlines the main concepts upon which supramolecular chemistry is based, clarifying the nature of supramolecular interactions and the principles of host-guest chemistry. In chapter 2 it is pointed out the use of ESR spectroscopy to investigate the properties of organic non-covalent assemblies in liquid solution by spin labels and spin probes. The chapter 3 deals with the synthesis of a new class of p-electron-deficient tetracationic cyclophane ring, carrying one or two paramagnetic side-arms based on 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) moiety. In the chapter 4, the Huisgen 1,3-dipolar cycloaddition is exploited to synthesize rotaxanes having paramagnetic cyclodextrins as wheels. In the chapter 5, the catalysis of Huisgen’s cycloaddition by CB[6] is exploited to synthesize paramagnetic CB[6]-based [3]-rotaxanes. In the chapter 6 I reported the first preliminary studies of Actinoid series as a new class of templates in catenanes’ synthesis. Being f-block elements, so having the property of expanding the valence state, they constitute promising candidates as chemical templates offering the possibility to create a complex with coordination number beyond 6.
Resumo:
Diskotische Hexa-peri-hexabenzocoronene (HBC) als molekulare, definierte graphitische Substrukturen sind bereits seit langem Gegenstand von Untersuchungen zu der Delokalisierung von π-Elektronen. In dieser Arbeit wurden zusätzlich Platin-Komplexe in das periphere Substitutionsmuster von HBC eingeführt. Dies führte zu einer Verbesserung der Emission von dem angeregten Triplett-Zustand in den Singulett-Grundzustand mit einer zusätzlichen Verlängerung der Lebensdauer des angeregten Zustandes. Zusätzlich erlaubte diese Konfiguration ein schnelles Intersystem-Crossing mittels einer verstärkten Spin-Orbit Kopplung, die sowohl bei tiefen Temperaturen, als auch bei Raumtemperatur exklusiv zu Phosphoreszenz (T1→S0) führte. Das Verständniss über solche Prozesse ist auch essentiell für die Entwicklung verbesserter opto-elektronischer Bauteile. Die Erstellung von exakt definierten molekularen Strukturen, die speziell für spezifische Interaktionen hergestellt wurden, machten eine Inkorporation von hydrophoben-hydrophilen, wasserstoffverbrückten oder elektrostatischen funktionalisierten Einheiten notwendig, um damit den supramolekularen Aufbau zu kontrollieren. Mit Imidazolium-Salzen funktionalisierte HBC Derivate wurden zu diesem Zwecke hergestellt. Eine interessante Eigenschaft dieser Moleküle ist ihre Amphiphilie. Dies gestattete die Untersuchung ihrer Eigenschaften in einem polaren Solvens und sowohl der Prozessierbarkeit als auch der Faserbildung auf Siliziumoxid-Trägern. Abhängig vom Lösungsmittel und der gewählten Konditionen konnten hochkristalline Fasern erhalten werden. Durch eine Substitution der HBCs mit langen, sterisch anspruchsvollen Seitenketten, konnte durch eine geeignete Prozessierung eine homöotrope Ausrichtung auf Substraten erreicht werden, was dieses Material interessant für photovoltaische Applikationen macht. Neuartige Polyphenylen-Metall-Komplexe mit diskotischen, linearen und dendritischen Geometrien wurden mittels einer einfachen Reaktion zwischen Co2(CO)8 und Ethinyl-Funktionalitäten in Dichlormethan hergestellt. Nach der Pyrolyse dieser Komplexe ergaben sich unterschiedliche Kohlenstoff-Nanopartikel, inklusive Nanoröhren, graphitischen Nanostäben und Kohlenstoff/Metall Hybrid Komplexe, die durch Elektronenmikroskopie untersucht wurden. Die resultierenden Strukturen waren dabei abhängig von der Zusammensetzung und Struktur der Ausgangssubstanzen. Anhand dieser Resultate ergeben sich diverse Möglichkeiten, um den Mechanismus, der zur Herstellung graphitischer Nanopartikel führt, besser zu verstehen.
Resumo:
This work of thesis involves various aspects of crystal engineering. Chapter 1 focuses on crystals containing crown ether complexes. Aspects such as the possibility of preparing these materials by non-solution methods, i.e. by direct reaction of the solid components, thermal behavior and also isomorphism and interconversion between hydrates are taken into account. In chapter 2 a study is presented aimed to understanding the relationship between hydrogen bonding capability and shape of the building blocks chosen to construct crystals. The focus is on the control exerted by shape on the organization of sandwich cations such as cobalticinium, decamethylcobalticinium and bisbenzenchromium(I) and on the aggregation of monoanions all containing carboxylic and carboxylate groups, into 0-D, 1-D, 2-D and 3-D networks. Reactions conducted in multi-component molecular assemblies or co-crystals have been recognized as a way to control reactivity in the solid state. The [2+2] photodimerization of olefins is a successful demonstration of how templated solid state synthesis can efficiently synthesize unique materials with remarkable stereoselectivity and under environment-friendly conditions. A demonstration of this synthetic strategy is given in chapter 3. The combination of various types of intermolecular linkages, leading to formation of high order aggregation and crystalline materials or to a random aggregation resulting in an amorphous precipitate, may not go to completeness. In such rare cases an aggregation process intermediate between crystalline and amorphous materials is observed, resulting in the formation of a gel, i.e. a viscoelastic solid-like or liquid-like material. In chapter 4 design of new Low Molecular Weight Gelators is presented. Aspects such as the relationships between molecular structure, crystal packing and gelation properties and the application of this kind of gels as a medium for crystal growth of organic molecules, such as APIs, are also discussed.
Resumo:
Iodide transport is necessary for the synthesis of thyroid hormones following accumulation in the follicular lumen out of thyroid cells, via channels unknown with the exception of pendrin. According to our hypothesis, TMEM16A could be the main molecular identity of the channel mediating iodide efflux in the thyroid gland. TMEM16A is the prior candidate for calcium-activated chloride conductance (CaCC). TMEM16A belongs to the TMEM16/anoctamin family comprising ten members (TMEM16A-K). Higher affinity of TMEM16A for iodide and predicted expression in the thyroid gland suggest its mediation of iodide efflux. The aim of this project was to identify the role of TMEM16A in iodide transport in the thyroid gland, by characterizing its molecular expression and functional properties. We demonstrated that TMEM16F, H, K transcripts are expressed in FRTL-5 thyroid cells, as well as TMEM16A, which is TSH-independent. Tumor tissue from human thyroid maintains TMEM16A expression. Functional in vivo experiments in FRTL-5, stably expressing YFP-H148Q/I152L fluorescent protein as a biosensor, showed that iodide efflux is stimulated by agonists of purinergic receptors with an order of potency of ATP>UTP>ADP (compatible with an involvement of P2Y purinergic receptors), and by agonists of adrenergic receptors (epinephrine, norepinephrine and phenylephrine). Iodide efflux was blocked by α-receptor antagonists prazosin and phentolamine, consistent with a role of α1 adrenergic receptors. Iodide efflux was specifically dependent on calcium mobilized from intracellular compartments and induced by the calcium ionophore ionomycin. CaCC blockers suppressed ionomycin-/ATP-/epinephrine-stimulated iodide efflux. Heterologous expression of TMEM16A in CHO K1 cells induced calcium-activated iodide fluxes. All these results support the hypothesis of the involvement of TMEM16A in calcium-dependent iodide efflux induced by receptor agonists in thyroid cells. TMEM16A may represent a new pharmacological target for thyroid cancer therapy, since its blockade may enhance the retention of radioiodide by tumour cells enhancing the efficacy of radioablative therapy.
Resumo:
Inflammatory Bowel Diseases (IBD) are intestinal chronic relapsing diseases which ethiopathogenesis remains uncertain. Several group have attempted to study the role of factors involved such as genetic susceptibility, environmental factors such as smoke, diet, sex, immunological factors as well as the microbioma. None of the treatments available satisfy several criteria at the same time such as safety, long-term remission, histopatological healing, and specificity. We used two different approaches for the development of new therapeutic treatment for Inflammatory Bowel Disease. The first is focused on the understanding of the potential role of functional food and nutraceuticals nutrients in the treatment of IBD. To do so, we investigated the role of Curcuma longa in the treatment of chemical induced colitis in mice model. Since Curcma Longa has been investigated for its antinflammatory role related to the TNFα pathway as well investigators have reported few cases of patients with ulcerative colites treated with this herbs, we harbored the hypothesis of a role of Curcuma Longa in the treatment f IBD as well as we decided to assess its role in intestinal motility. The second part is based on an immunological approach to develop new drugs to induce suppression in Crohn’s disease or to induce mucosa immunity such as in colonrectal tumor. The main idea behind this approach is that we could manipulate relevant cell-cell interactions using synthetic peptides. We demonstrated the role of the unique interaction between molecules expressed on intestinal epithelial cells such as CD1d and CEACAM5 and on CD8+ T cells. In normal condition this interaction has a role for the expansion of the suppressor CD8+ T cells. Here, we characterized this interaction, we defined which are the epitope involved in the binding and we attempted to develop synthetic peptides from the N domain of CEACAM5 in order to manipulate it.
Resumo:
Background. Human small cell lung cancer (SCLC) accounting for approximately 15-20% of all lung cancers, is an aggressive tumor with high propensity for early regional and distant metastases. Although the initial tumor rate response to chemotherapy is very high, SCLC relapses after approximately 4 months in ED and 12 months in LD. Basal cell carcinoma (BCC) is the most prevalent cancer in the western world, and its incidence is increasing worldwide. This type of cancer rarely metastasizes and the death rate is extraordinary low. Surgery is curative for most of the patients, but for those that develop locally advanced or metastatic BCC there is currently no effective treatment. Both types of cancer have been deeply investigated and genetic alterations, MYCN amplification (MA) among the most interesting, have been found. These could become targets of new pharmacological therapies. Procedures. We created and characterized novel BLI xenograft orthotopic mouse models of SCLC to evaluate the tumor onset and progression and the efficacy of new pharmacological strategies. We compared an in vitro model with a transgenic mouse model of BCC, to investigate and delineate the canonical HH signalling pathway and its connections with other molecular pathways. Results and conclusions. The orthotopic models showed latency and progression patterns similar to human disease. Chemotherapy treatments improved survival rates and validated the in vivo model. The presence of MA and overexpression were confirmed in each model and we tested the efficacy of a new MYCN inhibitor in vitro. Preliminar data of BCC models highlighted Hedgehog pathway role and underlined the importance of both in vitro and in vivo strategies to achieve a better understanding of the pathology and to evaluate the applicability of new therapeutic compounds
Resumo:
Enterobacteriaceae genomes evolve through mutations, rearrangements and horizontal gene transfer (HGT). The latter evolutionary pathway works through the acquisition DNA (GEI) modules of foreign origin that enhances fitness of the host to a given environment. The genome of E. coli IHE3034, a strain isolated from a case of neonatal meningitis, has recently been sequenced and its subsequent sequence analysis has predicted 18 possible GEIs, of which: 8 have not been previously described, 5 fully meet the pathogenic island definition and at least 10 that seem to be of prophagic origin. In order to study the GEI distribution of our reference strain, we screened for the presence 18 GEIs a panel of 132 strains, representative of E. coli diversity. Also, using an inverse nested PCR approach we identified 9 GEI that can form an extrachromosomal circular intermediate (CI) and their respective attachment sites (att). Further, we set up a qPCR approach that allowed us to determine the excision rates of 5 genomic islands in different growth conditions. Four islands, specific for strains appertaining to the sequence type complex 95 (STC95), have been deleted in order to assess their function in a Dictyostelium discoideum grazing assays. Overall, the distribution data presented here indicate that 16 IHE3034 GEIs are more associated to the STC95 strains. Also the functional and genetic characterization has uncovered that GEI 13, 17 and 19 are involved in the resistance to phagocitation by Dictyostelium d thus suggesting a possible role in the adaptation of the pathogen during certain stages of infection.
Resumo:
The discovery of the Cosmic Microwave Background (CMB) radiation in 1965 is one of the fundamental milestones supporting the Big Bang theory. The CMB is one of the most important source of information in cosmology. The excellent accuracy of the recent CMB data of WMAP and Planck satellites confirmed the validity of the standard cosmological model and set a new challenge for the data analysis processes and their interpretation. In this thesis we deal with several aspects and useful tools of the data analysis. We focus on their optimization in order to have a complete exploitation of the Planck data and contribute to the final published results. The issues investigated are: the change of coordinates of CMB maps using the HEALPix package, the problem of the aliasing effect in the generation of low resolution maps, the comparison of the Angular Power Spectrum (APS) extraction performances of the optimal QML method, implemented in the code called BolPol, and the pseudo-Cl method, implemented in Cromaster. The QML method has been then applied to the Planck data at large angular scales to extract the CMB APS. The same method has been applied also to analyze the TT parity and the Low Variance anomalies in the Planck maps, showing a consistent deviation from the standard cosmological model, the possible origins for this results have been discussed. The Cromaster code instead has been applied to the 408 MHz and 1.42 GHz surveys focusing on the analysis of the APS of selected regions of the synchrotron emission. The new generation of CMB experiments will be dedicated to polarization measurements, for which are necessary high accuracy devices for separating the polarizations. Here a new technology, called Photonic Crystals, is exploited to develop a new polarization splitter device and its performances are compared to the devices used nowadays.
Resumo:
There is an urgent need to improve the performance of urine cytology for the diagnosis of bladder cancer. In preliminary studies, telomerase activity evaluated by telomeric repeat amplification protocol (TRAP) assay and chromosomal aneuploidy detected by fluorescence in situ hybridization (FISH) in the diagnosis of bladder cancer have produced important results. Urine cell-free (UCF) DNA has also been proposed as a potential marker for early bladder cancer diagnosis. In the first study the diagnostic performance of TRAP assay and FISH analysis was assessed, while the second study evaluated the potential role of UCF DNA integrity in early bladder cancer diagnosis. In the first cross-sectional study, 289 consecutive patients who presented with urinary symptoms underwent cystoscopy and cytology evaluation. In the second study, UCF DNA was isolated from 51 bladder cancer patients, 46 symptomatic patients, and 32 healthy volunteers. c-Myc, BCAS1 and HER2 gene sequences longer than 250 bp were quantified by real time PCR to verify UCF DNA integrity. In the first study, sensitivity and specificity were 0.39 and 0.83, respectively, for cytology; 0.66 and 0.72 for TRAP; 0.78 and 0.60 for the cytology and TRAP combination; 0.78 and 0.78 for the cytology, TRAP and FISH combination; and 0.65 and 0.93 for the TRAP and FISH combination. In the second study, at the best cutoff of 0.1 ng/µl, UCF DNA integrity analysis showed a sensitivity of 0.73 and a specificity of 0.84 in healthy individuals and 0.83 in symptomatic patients. The preliminary results suggest that these biomarkers could potentially be used for the early diagnosis of bladder cancer, especially in high-risk populations (e.g, symptomatic individuals exposed to occupational risk) who may benefit from the use of noninvasive diagnostic tests in terms of cost-benefit.
Resumo:
Specific language impairment (SLI) is a complex neurodevelopmental disorder defined as an unexpected failure to develop normal language abilities for no obvious reason. Copy number variants (CNVs) are an important source of variation in the susceptibility to neuropsychiatric disorders. Therefore, a CNV study within SLI families was performed to investigate the role of structural variants in SLI. Among the identified CNVs, we focused on CNVs on chromosome 15q11-q13, recurrently observed in neuropsychiatric conditions, and a homozygous exonic microdeletion in ZNF277. Since this microdeletion falls within the AUTS1 locus, a region linked to autism spectrum disorders (ASD), we investigated a potential role of ZNF277 in SLI and ASD. Frequency data and expression analysis of the ZNF277 microdeletion suggested that this variant may contribute to the risk of language impairments in a complex manner, that is independent of the autism risk previously described in this region. Moreover, we identified an affected individual with a dihydropyrimidine dehydrogenase (DPD) deficiency, caused by compound heterozygosity of two deleterious variants in the gene DPYD. Since DPYD represents a good candidate gene for both SLI and ASD, we investigated its involvement in the susceptibility to these two disorders, focusing on the splicing variant rs3918290, the most common mutation in the DPD deficiency. We observed a higher frequency of rs3918290 in SLI cases (1.2%), compared to controls (~0.6%), while no difference was observed in a large ASD cohort. DPYD mutation screening in 4 SLI and 7 ASD families carrying the splicing variant identified six known missense changes and a novel variant in the promoter region. These data suggest that the combined effect of the mutations identified in affected individuals may lead to an altered DPD activity and that rare variants in DPYD might contribute to a minority of cases, in conjunction with other genetic or non-genetic factors.
Resumo:
The aim of my PhD research project was to investigate new and more sustainable routes, compared to those currently used, for the production of adipic acid (AA). AA is a very important chemical intermediate. The main use of AA is the production of Nylon-6,6 fibers, resins, polyesters, plasticizers. My project was divided into two parts: 1. The two-step oxidation of cyclohexene, where the latter is first oxidized into trans-1,2-cyclohexanediol (CHD) with aqueous hydrogen peroxide, and then the glycol is transformed into AA by reaction with molecular oxygen. Various catalysts were investigated in this process, both heterogeneous (alumina-supported Ru(OH)x and Au nanoparticles supported on TiO2, MgO and Mg(OH)2) and homogeneous (polyoxometalates). We also studied the mechanism of CHD oxidation with oxygen in the presence of these catalysts. 2. Baeyer-Villiger oxidation of cyclohexanone with aqueous hydrogen peroxide into ɛ-caprolactone, as a first step on the way to produce AA. Study on the mechanism of the uncatalyzed (thermal) oxidation of cyclohexanone were also carried out. Investigation on how the different heterogeneous catalysts affect the formation of the reaction products and their distribution was done.
Resumo:
This thesis describes the developments of new models and toolkits for the orbit determination codes to support and improve the precise radio tracking experiments of the Cassini-Huygens mission, an interplanetary mission to study the Saturn system. The core of the orbit determination process is the comparison between observed observables and computed observables. Disturbances in either the observed or computed observables degrades the orbit determination process. Chapter 2 describes a detailed study of the numerical errors in the Doppler observables computed by NASA's ODP and MONTE, and ESA's AMFIN. A mathematical model of the numerical noise was developed and successfully validated analyzing against the Doppler observables computed by the ODP and MONTE, with typical relative errors smaller than 10%. The numerical noise proved to be, in general, an important source of noise in the orbit determination process and, in some conditions, it may becomes the dominant noise source. Three different approaches to reduce the numerical noise were proposed. Chapter 3 describes the development of the multiarc library, which allows to perform a multi-arc orbit determination with MONTE. The library was developed during the analysis of the Cassini radio science gravity experiments of the Saturn's satellite Rhea. Chapter 4 presents the estimation of the Rhea's gravity field obtained from a joint multi-arc analysis of Cassini R1 and R4 fly-bys, describing in details the spacecraft dynamical model used, the data selection and calibration procedure, and the analysis method followed. In particular, the approach of estimating the full unconstrained quadrupole gravity field was followed, obtaining a solution statistically not compatible with the condition of hydrostatic equilibrium. The solution proved to be stable and reliable. The normalized moment of inertia is in the range 0.37-0.4 indicating that Rhea's may be almost homogeneous, or at least characterized by a small degree of differentiation.