2,192 research outputs found

    The crystal morphology and growth rates of triclinic N-docosane crystallising from N-dodecane solutions

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    A detailed analysis of the crystal morphology of triclinic n-docosane (C22H46) is presented together with a preliminary assessment of the supersaturation-dependence of the growth rates for the predicted (hkl) faces. A methodology to index the experimentally observed crystal faces, based on a combined BFDH and zone axis methodology is defined. Analysis using this methodology yields the morphological indexation of n-docosane to be (001), (112), (102), (010), and (1 - 33) or (130) based on the expected triclinic crystal structure. Crystals of n-docosane growing from supersaturated n-dodecane (C12 H26) solutions, as studied using in-situ optical microscopy, at three different supersaturation (σ) levels 0.01, 0.02 and 0.05, reveal that the crystal morphology changes with increasing in supersaturation, evolving from a habit consistent with a triclinic crystal system to a habit that is perhaps more representative of an orthorhombic structure. Growth rates determined for the (112) and (102) faces as well as for those less dominant faces range between 0.51 and 9.85 mm/s, in good agreement with previously reported data for other organic molecules including n-alkanes

    A REGIÃO METROPOLITANA DE NATAL-RN: UM PROCESSO AINDA EM CURSO

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    A institucionalização das Regiões Metropolitanas (RMs) brasileiras obedeceu a duas fases. A primeira, nos anos de 1970, como parte da política de desenvolvimento urbano, relacionada à expansão da produção industrial e à consolidação das metrópoles como lócus desse processo. Reguladas por legislação federal, foram criadas, a princípio, nove RMs. A segunda teve início com a Constituição Federal de 1988, que facultou aos estados federados a competência de institucionalização de suas unidades regionais. Nesse sentido, chegava ao fim um modelo que criou regiões sobre as quais os estados federados não tinham autonomia e se abria a possibilidade de inserção de RMs em processos estaduais de planejamento regional. Na atualidade, observamos que grande parte dessas áreas metropolitanas no Brasil não tem um perfil bem definido, nem caracterização própria e, muito menos, identidade metropolitana. Desse modo, vazios urbanos consideráveis são identificados entre municípios de RMs bem como ausência de problemas comuns, gerando sérios problemas socioespaciais nessas áreas. No caso da RMN (Região Metropolitana de Natal), observamos que esta a cada dia está se consolidando enquanto processo em curso, guardando algumas especificidades nesse processo recente de formação

    Nonlinear Dynamics of the Perceived Pitch of Complex Sounds

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    We apply results from nonlinear dynamics to an old problem in acoustical physics: the mechanism of the perception of the pitch of sounds, especially the sounds known as complex tones that are important for music and speech intelligibility

    Patient reported cosmetic outcome after vacuum assisted excision of benign breast lesions:a cross-sectional study

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    OBJECTIVE: Better cosmetic outcome after vacuum assisted excision (VAE) compared to surgical excision of benign breast lesions is suggested in previous studies but has never been evaluated with validated outcome measures. In this study, patient reported cosmetic outcome after VAE was evaluated. METHODS: Patients who underwent VAE between July 2017 and December 2018 were invited to complete the cosmetic subscale of the Dutch Breast Cancer Treatment Outcome Scale, comparing the treated with the untreated breast. Response mode ranged from 1 (no difference) to 4 (large difference) and cosmetic outcome was calculated as the unweighted mean. Clinical outcomes included: tumor size, number of cores, complications, residual lesions and recurrences. RESULTS: Response rate was 73.4% (47 of 64 patients). Median tumor size was 15 mm (range 5-51 mm) and median number of cores 6.5 (range 1-85), complete excision was confirmed in all but two patients. Mean cosmetic outcome was good (mean score ≤1.75) in 74% of patients and no patients reported a poor cosmetic outcome (mean score >3.25). A hematoma occurred in five patients (one needed aspiration) and a skin rash in one patient, no patients developed an infection or seroma. CONCLUSION: In this study VAE is safe and effective for tumors up to 5 cm and patient reported cosmetic outcome was good. Patients with benign lesions could benefit from VAE as an alternative for surgical excision. ADVANCES IN KNOWLEDGE: A formal quantitative measurement of cosmetic outcome after vacuum assisted excision for benign breast lesions was still lacking. This study shows that this cosmetic outcome is overall good in benign lesions up to 5 cm

    Randomized controlled trial comparing magnetic marker localization (MaMaLoc) with wire-guided localization in the treatment of early-stage breast cancer

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    Wire-guided localization (WGL) is the standard of care in the surgical treatment of nonpalpable breast tumors. In this study, we compare the use of a new magnetic marker localization (MaMaLoc) technique to WGL in the treatment of early-stage breast cancer patients. Open-label, single-center, randomized controlled trial comparing MaMaLoc (intervention) to WGL (control) in women with early-stage breast cancer. Primary outcome was surgical usability measured using the System Usability Scale (SUS, 0-100 score). Secondary outcomes were patient reported, clinical, and pathological outcomes such as retrieval rate, operative time, resected specimen weight, margin status, and reoperation rate. Thirty-two patients were analyzed in the MaMaLoc group and 35 in the WGL group. Patient and tumor characteristics were comparable between groups. No in situ complications occurred. Retrieval rate was 100% in both groups. Surgical usability was higher for MaMaLoc: 70.2 ± 8.9 vs. 58.1 ± 9.1, p < 0.001. Patients reported higher overall satisfaction with MaMaLoc (median score 5/5) versus WGL (score 4/5), p < 0.001. The use of magnetic marker localization (MaMaLoc) for early-stage breast cancer is effective and has higher surgical usability than standard WGL
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