Instituto Politécnico Nacional

About: Instituto Politécnico Nacional is a education organization based out in Mexico City, Mexico. It is known for research contribution in the topics: Population & Context (language use). The organization has 43351 authors who have published 63315 publications receiving 938532 citations. The organization is also known as: Instituto Politécnico Nacional & Instituto Politecnico Nacional.

Hydrogen‐Bonded Semiconducting Pigments for Air‐Stable Field‐Effect Transistors

Abstract: Extensive intramolecular π-conjugation is considered to be requisite in the design of organic semiconductors. Here, two inkjet pigments, epindolidione and quinacridone, that break this design rule are explored. These molecules afford intermolecular π-stacking reinforced by hydrogen-bonding bridges. Air-stable organic field effect transistors are reported that support mobilities up to 1.5 cm(2)/Vs with T80 lifetimes comparable with the most stable reported organic semiconducting materials.

Busulfan and melphalan versus carboplatin, etoposide, and melphalan as high-dose chemotherapy for high-risk neuroblastoma (HR-NBL1/SIOPEN): an international, randomised, multi-arm, open-label, phase 3 trial

Abstract: Summary Background High-dose chemotherapy with haemopoietic stem-cell rescue improves event-free survival in patients with high-risk neuroblastoma; however, which regimen has the greatest patient benefit has not been established. We aimed to assess event-free survival after high-dose chemotherapy with busulfan and melphalan compared with carboplatin, etoposide, and melphalan. Methods We did an international, randomised, multi-arm, open-label, phase 3 cooperative group clinical trial of patients with high-risk neuroblastoma at 128 institutions in 18 countries that included an open-label randomised arm in which high-dose chemotherapy regimens were compared. Patients (age 1–20 years) with neuroblastoma were eligible to be randomly assigned if they had completed a multidrug induction regimen (cisplatin, carboplatin, cyclophosphamide, vincristine, and etoposide with or without topotecan, vincristine, and doxorubicin) and achieved an adequate disease response. Patients were randomly assigned (1:1) to busulfan and melphalan or to carboplatin, etoposide, and melphalan by minimisation, balancing age at diagnosis, stage, MYCN amplification, and national cooperative clinical group between groups. The busulfan and melphalan regimen comprised oral busulfan (150 mg/m 2 given on 4 days consecutively in four equal doses); after Nov 8, 2007, intravenous busulfan was given (0·8–1·2 mg/kg per dose for 16 doses according to patient weight). After 24 h, an intravenous melphalan dose (140 mg/m 2 ) was given. Doses of busulfan and melphalan were modified according to bodyweight. The carboplatin, etoposide, and melphalan regimen consisted of carboplatin continuous infusion of area under the plasma concentration–time curve 4·1 mg/mL per min per day for 4 days, etoposide continuous infusion of 338 mg/m 2 per day for 4 days, and melphalan 70 mg/m 2 per day for 3 days, with doses for all three drugs modified according to bodyweight and glomerular filtration rate. Stem-cell rescue was given after the last dose of high-dose chemotherapy, at least 24 h after melphalan in patients who received busulfan and melphalan and at least 72 h after carboplatin etoposide, and melphalan. All patients received subsequent local radiotherapy to the primary tumour site followed by maintenance therapy. The primary endpoint was 3-year event-free survival, analysed by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01704716, and EudraCT, number 2006-001489-17. Findings Between June 24, 2002, and Oct 8, 2010, 1347 patients were enrolled and 676 were eligible for random allocation, 598 (88%) of whom were randomly assigned: 296 to busulfan and melphalan and 302 to carboplatin, etoposide, and melphalan. Median follow-up was 7·2 years (IQR 5·3–9·2). At 3 years, 146 of 296 patients in the busulfan and melphalan group and 188 of 302 in the carboplatin, etoposide, and melphalan group had an event; 3-year event-free survival was 50% (95% CI 45–56) versus 38% (32–43; p=0·0005). Nine patients in the busulfan and melphalan group and 11 in the carboplatin, etoposide, and melphalan group had died without relapse by 5 years. Severe life-threatening toxicities occurred in 13 (4%) patients who received busulfan and melphalan and 29 (10%) who received carboplatin, etoposide, and melphalan. The most frequent grade 3–4 adverse events were general condition (74 [26%] of 281 in the busulfan and melphalan group vs 103 [38%] of 270 in the carboplatin, etoposide, and melphalan group), infection (55 [19%] of 283 vs 74 [27%] of 271), and stomatitis (138 [49%] of 284 vs 162 [59%] of 273); 60 (22%) of 267 patients in the busulfan and melphalan group had Bearman grades 1–3 veno-occlusive disease versus 21 (9%) of 239 in the carboplatin, etoposide, and melphalan group. Interpretation Busulfan and melphalan improved event-free survival in children with high-risk neuroblastoma with an adequate response to induction treatment and caused fewer severe adverse events than did carboplatin, etoposide, and melphalan. Busulfan and melphalan should thus be considered standard high-dose chemotherapy and ongoing randomised studies will continue to aim to optimise treatment for high-risk neuroblastoma. Funding European Commission 5th Framework Grant and the St Anna Kinderkrebsforschung.

Constraints on dark matter annihilation in clusters of galaxies with the Fermi large area telescope

Abstract: Nearby clusters and groups of galaxies are potentially bright sources of high-energy gamma-ray emission resulting from the pair-annihilation of dark matter particles. However, no significant gamma-ray emission has been detected so far from clusters in the first 11 months of observations with the Fermi Large Area Telescope. We interpret this non-detection in terms of constraints on dark matter particle properties. In particular for leptonic annihilation final states and particle masses greater than ~200 GeV, gamma-ray emission from inverse Compton scattering of CMB photons is expected to dominate the dark matter annihilation signal from clusters, and our gamma-ray limits exclude large regions of the parameter space that would give a good fit to the recent anomalous Pamela and Fermi-LAT electron-positron measurements. We also present constraints on the annihilation of more standard dark matter candidates, such as the lightest neutralino of supersymmetric models. The constraints are particularly strong when including the fact that clusters are known to contain substructure at least on galaxy scales, increasing the expected gamma-ray flux by a factor of ~5 over a smooth-halo assumption. We also explore the effect of uncertainties in cluster dark matter density profiles, finding a systematic uncertainty in the constraints of roughly a factor of two, but similar overall conclusions. In this work, we focus on deriving limits on dark matter models; a more general consideration of the Fermi-LAT data on clusters and clusters as gamma-ray sources is forthcoming.

Origin of the superior adhesive performance of mushroom-shaped microstructured surfaces

Abstract: The superlative adhesive properties of some biological attachment systems, such as those of geckos, spiders, and insects, have inspired researchers from different fields (e.g. biology, physics and engineering) to conceive and design man-made microstructured surfaces that might mimic their performance. Among the several proposed designs, very recently mushroom-shaped adhesive microstructures have drawn the interest of scientists and engineers, because experiments have proved their superiority compared to other micro- and nano-structures. In this article, we explain theoretically the physical mechanism behind the enhanced adhesion of such microstructures, and provide for the first time a useful tool to predict adhesive performance depending on the geometry, mechanical properties of the material, and energy of adhesion. Our theoretical predictions are strongly supported by the available experimental data. The present study can streamline the optimisation of adhesive microstructures for industrial applications.