Resolución algebraica de problemas estequiométricos

La resolución de problemas, entendida como la metodología para enfrentar situaciones nuevas que impliquen un reto personal, es una estrategia didáctica eficaz que permite generar, consolidar e integrar conocimientos. La resolución de un problema típico en ciencias parte de la comprensión de su enunciado, constituido por un texto corto escrito en lenguaje natural; la traducción de dicha situación al lenguaje matemático constituye un obstáculo en el proceso de resolución de problemas con estructura matemática subyacente. Para desarrollar en los estudiantes de ingeniería química las habilidades matemática y de traducción de lenguajes coloquial-científico-algebraico, se diseñaron enunciados de problemas basados en la estequiometría de compuestos y reacciones, los cuales involucran el planteamiento y resolución de sistemas de ecuaciones algebraicas lineales

Balancing porosity and mechanical properties of titanium samples to favor cellular growth against bacteria

Two main problems limit the success of titanium implants: bacterial infection, which restricts their osseointegration capacity; and the stiffness mismatch between the implant and the host cortical bone, which promotes bone resorption and risk of fracture. Porosity incorporation may reduce this difference in stiffness but compromise biomechanical behavior. In this work, the relationship between the microstructure (content, size, and shape of pores) and the antibacterial and cellular behavior of samples fabricated by the space-holder technique (50 vol % NH4HCO3 and three ranges of particle sizes) is established. Results are discussed in terms of the best biomechanical properties and biofunctional activity balance (cell biocompatibility and antibacterial behavior). All substrates achieved suitable cell biocompatibility of premioblast and osteoblast in adhesion and proliferation processes. It is worth to highlighting that samples fabricated with the 100–200 μm space-holder present better mechanical behavior—in terms of stiffness, microhardness, and yield strength—which make them a very suitable material to replace cortical bone tissues. Those results exposed the relationship between the surface properties and the race of bacteria and mammalian cells for the surface with the aim to promote cellular growth over bacteria.University of Seville (Spain) VI Plan Propio de Investigación y Transferencia—US 2018, I.3A

Study of the effects of ionic liquid-modified cathodes and ceramic separators on MFC performance

© 2016 Elsevier B.V. Ceramic-based MFC designs have proven to be a low cost alternative for power production and wastewater treatment. The use of ionic liquids in ceramic MFCs is explored for the first time in the present work in order to improve power output. The ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][Tf2N], has been selected for this purpose due to its advantageous properties. The performance of activated carbon cathodes using polytetrafluoroethylene (PTFE) binder and different carbon diffusion layers (DL) (controls) is compared with two types of ionic liquid-modified cathodes (test). This work continues to study the performance of terracotta separators modified with the same ionic liquid, neat and also mixed with PTFE. Whilst the results show operational limitations when the IL is integrated in the ceramic separator, there is a significant enhancement of the MFC performance when added as part of the activated layer mixture of the cathode, achieving up to 86.5% more power output in comparison with IL-free MFCs (from 229.78 μW to 428.65 μW). The addition of a layer of PTFE-mixed ionic liquid spread on the activated layer of the cathode also leads to an increase in power of approximately 37%

DLT 4-411. Scale : the development of the typical speech

1 archivo PDF (18 páginas). fhundequinquagintaLas características de una escala cuyo propósito consiste en determinar fidedignamente el nivel del desarrollo del lenguaje típico en niños de edad preescolar se describen en este artículo. La escala referida evalúa el desarrollo del proceso para adquirir la fonología, morfología, sintaxis y pragmática de niños hablantes del español cuyas edades se hallen delimitadas por 4 años y 4 años 11 meses. Abstract The characteristics and the process of developing a scale that aims at determining the level of typical language development in children of pre school age are described in this article. The scale assesses the above mentioned development of phonology, morphology, syntax and pragmatics of children whose ages are between four and four years eleven months. PALABRAS CLAVE: adquisición, evaluación, lenguaje, escala. KEY WORDS: acquisition, assessment, language, leve

Acoustically Levitated Whispering-Gallery Mode Microlasers

Acoustic levitation has become a crucial technique for contactless manipulation in several fields, particularly in biological applications. However, its application in the photonics field remains largely unexplored. In this study, we implement an affordable and innovative phased-array levitator that enables stable trapping in the air of micrometer dye-doped droplets, thereby enabling the creation of microlasers. For the first time, this paper presents a detailed performance of the levitated microlaser cavity, supported by theoretical analysis concerning the hybrid technology based on the combination of whispering-gallery modes and acoustic fields. The pressure field distribution inside the acoustic cavity is numerically solved and qualitatively matched with the schlieren deflectometry technique. The optical lasing features of the levitated microlasers are highly comparable with those devices based On-a-Chip registering maximum Q-factors of ~ 105, and minimum lasing thresholds ~ 150 nJ cm−2. The emission comb is explained as a sum of multiple individual-supported whispering-gallery modes. The use of novel touchless micrometric lasers, produced with an acoustic levitator brings new technological opportunities based on photonic-acoustic technological platforms

Pulsed electromagnetic field - a cultivation practice used to increase soybean seed germination and yield

The aim of the research was to test the effect of pulsed electromagnetic field (PEMF) on soybean seed germination and yield depending on specific field conditions, years of study, exposure duration and frequency. Field trial was conducted on an experimental field of Institute of Field and Vegetable Crops in Novi Sad, Serbia in 2010-2013. Seeds of the soybean (Glycine hispida (Moench)) medium-early cultivar. Valjevka 'were exposed to the PEMF therapy using the impulse generator and strip. Low-frequency (16, 24, 30 and 72 Hz) PEMF was used in the duration of 0, 30, 60 and 90 minutes. Research results indicate that this method can increase seed germination up to 8.00% and yield by 960.5 kg, or 21% in field conditions, which is a significant increase and a solid basis to introduce this practice, primarily in organic production with a very limited use of seed treatment preparations. However, the practice can have an inhibitory effect under an unfavourable combination of exposure duration and frequency. The obtained data were processed using the analysis of variance of three-factorial trials considering all years of study. Due to different meteorological conditions in the study years, analysis of variance was conducted for each year of study and correlations between the tested traits were examined

Prevalence and Population Diversity of Listeria monocytogenes Isolated from Dairy Cattle Farms in the Cantabria Region of Spain

Listeria monocytogenes is an opportunistic pathogen that is widely distributed in the environment. Here we show the prevalence and transmission of L. monocytogenes in dairy farms in the Cantabria region, on the northern coast of Spain. A total of 424 samples was collected from 14 dairy farms (5 organic and 9 conventional) and 211 L. monocytogenes isolates were recovered following conventional microbiological methods. There were no statistically significant differences in antimicrobial resistance ratios between organic and conventional farms. A clonal relationship among the isolates was assessed by pulsed field gel electrophoresis (PFGE) analysis and 64 different pulsotypes were obtained. Most isolates (89%, n = 187) were classified as PCR serogroup IVb by using a multiplex PCR assay. In this case, 45 isolates of PCR serogroup IVb were whole genome-sequenced to perform a further analysis at genomic level. In silico MLST analysis showed the presence of 12 sequence types (ST), of which ST1, ST54 and ST666 were the most common. Our data indicate that the environment of cattle farms retains a high incidence of L. monocytogenes, including subtypes involved in human listeriosis reports and outbreaks. This pathogen is shed in the feces and could easily colonize dairy products, as a result of fecal contamination. Effective herd and manure management are needed in order to prevent possible outbreaks.This work was supported by Research Project grants RTA08-099, RTA2008-00080-C02, RTA2014-00045-C03-01 (INIA and FEDER) from the Spanish Ministry of Economy and Competitiveness and RTI2018-098267-R-C31 (INIA and FEDER) from the Spanish Ministry of Science and Innovation.S

Potential Use of Near-Infrared Spectroscopy to Predict Fatty Acid Profile of Meat from Different European Autochthonous Pig Breeds

Autochthonous pig breeds provide products of differentiated quality, among which quality control is difficult to perform and insufficient for current market requirements. The present research evaluates the predictive ability of near‐infrared (NIR) spectroscopy, combined with chemometric methods as a rapid and affordable tool to assure traceability and quality control. Thus, NIR technology was assessed for intact and minced muscle Longissimus thoracis et lumborum samples collected from 12 European autochthonous pig breeds for the quantification of lipid content and fatty acid composition. Different tests were performed using different numbers of samples for calibration and validation. The best predictive ability was found using minced presentation and set with 80% of the samples for the calibration and the remaining 20% for the external validation test for the following traits: lipid content and saturated and polyunsaturated fatty acids, which attained both the highest determination coefficients (0.89, 0.61, and 0.65, respectively) and the lowest root mean square errors in external validation (0.62, 1.82, and 1.36, respectively). Lower predictive ability was observed for intact muscles. These results could contribute to improve the management of autochthonous breeds and to ensure quality of their products by traditional meat industry chains

Withdrawal of infliximab therapy in ankylosing spondylitis in persistent clinical remission, results from the REMINEA study

Altres ajuts: This work is conducted under the umbrella of the Rheumatology Society of Catalonia and supported by Merck Research Laboratories.Background: Recent data suggest that anti-TNF doses can be reduced in ankylosing spondylitis (AS) patients. Some authors even propose withdrawing treatment in patients in clinical remission; however, at present there is no evidence to support this. Objective: To assess how long AS patients with persistent clinical remission remained free of flares after anti-TNF withdrawal and to evaluate the effects of treatment reintroduction. We also analyze the characteristics of patients who did not present clinical relapse. Methods: Multicenter, prospective, observational study of a cohort of patients with active AS who had received infliximab as a first anti-TNF treatment and who presented persistent remission (more than 6 months). We recorded at baseline and every 6-8 weeks over the 12-month period the age, gender, disease duration, peripheral arthritis or enthesitis, HLA-B27 status, BASDAI, CRP, ESR, BASFI, and three visual analogue scales, spine global pain, spinal night time pain, and patient's global assessment. Results: Thirty-six out of 107 patients (34%) presented persistent remission and were included in our study. After treatment withdrawal, 21 of these 36 patients (58%) presented clinical relapse during follow-up. Infliximab therapy was reintroduced and only 52% achieved clinical remission, as they had before the discontinuation of infliximab; in an additional 10%, reintroduction of infliximab was ineffective, obliging us to change the anti-TNF therapy. No clinical or biological factors were associated with the occurrence of relapse during the follow-up. Conclusions: Two thirds of patients in clinical remission presented clinical relapse shortly after infliximab withdrawal. Although the reintroduction of infliximab treatment was safe, half of the patients did not present the same clinical response that they had achieved prior to treatment withdrawal