208 research outputs found

    Investigation of the PI Control Parameters on the Low Temperature Synthesis of 2-octanone

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    Temperature control is probably the most important factor that influences a chemical reaction yield, in particular when working with strongly exothermic reactions. The oxidation of 2-octanol to 2-octanone is a well-known two phase (liquid-liquid) oxidation reaction, and it suffers of yield loss due to side reactions that lead to further oxidation to a mixture of carboxylic acids. As the reaction is exothermic, controlling the reactor temperature is extremely important for a safe operation. A temperature control naturally induces fluctuations within the system, which can impact the kinetics of the desired reaction. The aim of this work is to investigate the impact of the Proportional-Integral temperature controller parameters on the conversion to 2-octanone. The reaction is carried out in a semi-batch reactor, dosing 2-octanol on a solution of nitric acid. The production of nitrosonium ion is promoted by adding sodium nitrite to the nitric acid. The reaction is carried out with high stirring speed, in order to work under full chemical control regime, avoiding the effect of material diffusion between the two phases. Several simulations were done referring to an EasymaxTM 402 Workstation (Mettler Toledo) under an isothermal temperature control mode. Target temperatures were chosen in the -15 - 15°C range. The proportional parameter was tested in the range of 5-15, and the integral parameter was kept in the range of 60-600 s. Results showed that runaway boundaries are significatively affected by the values of the temperature controller parameters, highlighting how it is fundamental a calorimetric investigation of the process in view of a safe process optimization

    Reciprocal insulation analysis of Hi-C data shows that TADs represent a functionally but not structurally privileged scale in the hierarchical folding of chromosomes

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    Understanding how regulatory sequences interact in the context of chromosomal architecture is a central challenge in biology. Chromosome conformation capture revealed that mammalian chromosomes possess a rich hierarchy of structural layers, from multi-megabase compartments to sub-megabase topologically associating domains (TADs) and sub-TAD contact domains. TADs appear to act as regulatory microenvironments by constraining and segregating regulatory interactions across discrete chromosomal regions. However, it is unclear whether other (or all) folding layers share similar properties, or rather TADs constitute a privileged folding scale with maximal impact on the organization of regulatory interactions. Here, we present a novel algorithm named CaTCH that identifies hierarchical trees of chromosomal domains in Hi-C maps, stratified through their reciprocal physical insulation, which is a single and biologically relevant parameter. By applying CaTCH to published Hi-C data sets, we show that previously reported folding layers appear at different insulation levels. We demonstrate that although no structurally privileged folding level exists, TADs emerge as a functionally privileged scale defined by maximal boundary enrichment in CTCF and maximal cell-type conservation. By measuring transcriptional output in embryonic stem cells and neural precursor cells, we show that the likelihood that genes in a domain are coregulated during differentiation is also maximized at the scale of TADs. Finally, we observe that regulatory sequences occur at genomic locations corresponding to optimized mutual interactions at the same scale. Our analysis suggests that the architectural functionality of TADs arises from the interplay between their ability to partition interactions and the specific genomic position of regulatory sequences

    Significance of glycolytic metabolism-related protein expression in colorectal cancer, lymph node and hepatic metastasis

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    Background: Colorectal cancer (CRC) is one of the most common malignancies and a leading cause of cancer death worldwide. Most cancer cells display high rates of glycolysis with production of lactic acid, which is then exported to the microenvironment by monocarboxylate transporters (MCTs). The main aim of this study was to evaluate the significance of MCT expression in a comprehensive series of primary CRC cases, lymph node and hepatic metastasis. Methods: Expressions of MCT1, MCT4, CD147 and GLUT1 were studied in human samples of CRC, lymph node and hepatic metastasis, by immunohistochemistry. Results: All proteins were overexpressed in primary CRC, lymph node and hepatic metastasis, when compared with non-neoplastic tissue, with exception of MCT1 in lymph node and hepatic metastasis. MCT1 and MCT4 expressions were associated with CD147 and GLUT1 in primary CRC. These markers were associated with clinical pathological features, reflecting the putative role of these metabolism-related proteins in the CRC setting. Conclusion: These findings provide additional evidence for the pivotal role of MCTs in CRC maintenance and progression, and support the use of MCTs as biomarkers and potential therapeutic targets in primary and metastatic CRC.This work was supported by the Fundação para a Ciência e a Tecnologia (FCT) grant ref. PTDC/SAU-FCF/104347/2008, under the scope of ‘Programa Operacional Temático Factores de Competitividade’ (COMPETE) of ‘Quadro Comunitário de Apoio III’ and co-financed by the Fundo Europeu De Desenvolvimento Regional (FEDER). Ricardo Amorim was recipient of the fellowship SFRH/BD/98002/2013, from Fundação para a Ciência e a Tecnologia (FCT Portugal).info:eu-repo/semantics/publishedVersio

    Noncoding deletions reveal a gene that is critical for intestinal function.

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    Large-scale genome sequencing is poised to provide a substantial increase in the rate of discovery of disease-associated mutations, but the functional interpretation of such mutations remains challenging. Here we show that deletions of a sequence on human chromosome 16 that we term the intestine-critical region (ICR) cause intractable congenital diarrhoea in infants1,2. Reporter assays in transgenic mice show that the ICR contains a regulatory sequence that activates transcription during the development of the gastrointestinal system. Targeted deletion of the ICR in mice caused symptoms that recapitulated the human condition. Transcriptome analysis revealed that an unannotated open reading frame (Percc1) flanks the regulatory sequence, and the expression of this gene was lost in the developing gut of mice that lacked the ICR. Percc1-knockout mice displayed phenotypes similar to those observed upon ICR deletion in mice and patients, whereas an ICR-driven Percc1 transgene was sufficient to rescue the phenotypes found in mice that lacked the ICR. Together, our results identify a gene that is critical for intestinal function and underscore the need for targeted in vivo studies to interpret the growing number of clinical genetic findings that do not affect known protein-coding genes

    Single-cell Transcriptomics reveals multi-step adaptations to endocrine therapy

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    Resistant tumours are thought to arise from the action of Darwinian selection on genetically heterogenous cancer cell populations. However, simple clonal selection is inadequate to describe the late relapses often characterising luminal breast cancers treated with endocrine therapy (ET), suggesting a more complex interplay between genetic and non-genetic factors. Here, we dissect the contributions of clonal genetic diversity and transcriptional plasticity during the early and late phases of ET at single-cell resolution. Using single-cell RNA-sequencing and imaging we disentangle the transcriptional variability of plastic cells and define a rare subpopulation of pre-adapted (PA) cells which undergoes further transcriptomic reprogramming and copy number changes to acquire full resistance. We find evidence for sub-clonal expression of a PA signature in primary tumours and for dominant expression in clustered circulating tumour cells. We propose a multi-step model for ET resistance development and advocate the use of stage-specific biomarkers

    Radiation resistant LGAD design

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    In this paper, we report on the radiation resistance of 50-micron thick LGAD detectors manufactured at the Fondazione Bruno Kessler employing several different doping combinations of the gain layer. LGAD detectors with gain layer doping of Boron, Boron low-diffusion, Gallium, Carbonated Boron and Carbonated Gallium have been designed and successfully produced. These sensors have been exposed to neutron fluences up to ϕn31016  n/cm2\phi_n \sim 3 \cdot 10^{16}\; n/cm^2 and to proton fluences up to ϕp91015  p/cm2\phi_p \sim 9\cdot10^{15}\; p/cm^2 to test their radiation resistance. The experimental results show that Gallium-doped LGADs are more heavily affected by initial acceptor removal than Boron-doped LGAD, while the presence of Carbon reduces initial acceptor removal both for Gallium and Boron doping. Boron low-diffusion shows a higher radiation resistance than that of standard Boron implant, indicating a dependence of the initial acceptor removal mechanism upon the implant width. This study also demonstrates that proton irradiation is at least twice more effective in producing initial acceptor removal, making proton irradiation far more damaging than neutron irradiation.Comment: 22 pages, 17 figure

    O processo de inclusão: da legislação à realidade: uma análise crítica

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    A presente monografia pretendeu fazer uma análise crítica do processo de construção da escola inclusiva, observando-se a compatibilização da legislação com o cotidiano escolar. Pretendeu-se verificar se a escola está atendendo à legislação no que se refere à formação do educador; se o espaço físico da mesma está suprindo às necessidades do aluno deficiente; se a escola está realizando a adaptação curricular de modo a atender aos alunos inclusivos; observar se os sistemas de apoio estão sendo ofertados; e, por fim, oferecer subsídios à comunidade escolar, no sentido de perceber a prescrição da lei e sua concomitante aplicação ao cotidiano escolar. Para tanto, a pesquisa foi realizada com 5 (cinco) professoras do ensino fundamental (1ª a 4ª séries) da rede regular de ensino público do DF(Taguatinga, Plano Piloto, Samambaia, Guará e Ceilândia). Os instrumentos utilizados foram a análise documental (leis, portarias, decretos) e a entrevista de caráter qualitativo/interpretativo abordando as categorias mencionadas, anteriormente, com a finalidade de subsidiar uma análise crítica do processo de inclusão e a compatibilização da legislação com o cotidiano escolar. Pode-se concluir, através deste estudo, que muitas modificações no âmbito da práxis ainda devem ser feitas e que a realidade escolar ainda não é condizente com a legislação. É notório o estabelecimento de medidas que visem assegurar os direitos conquistados, a melhoria da qualidade da educação, o investimento em uma ampla formação dos educadores, a remoção de barreiras físicas e atitudinais, a previsão e provisão de recursos materiais e humanos entre outras possibilidades. Nesta perspectiva potencializa- se um movimento de transformação da realidade para se conseguir reverter o percurso de exclusão de pessoas com ou sem deficiência no sistema educaciona
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