Mixed electrical conduction of calcium aluminates synthesized by polymeric precursors

A study of the electrical transport properties of calcium aluminate (CA) with coexisting C3A and C12A7 phases was carried out. In this work, powders resulting from synthesis based on the polymer precursor method. The resulting product was characterized by means of XRD, Raman, and UV-visible analysis to obtain the optical BG and by EIS. From the XRD and Raman analyses, the presence and coexistence of the two self-modified phases were confirmed. In this biphasic composition, celite phase was estimated to be the major phase. An optical BG of 5.69 eV at room temperature was calculated, and under the condition of a reducing atmosphere in the temperature range of 750-950 ºC, an activation energy for conduction of 2.98 eV was determined by EIS measurements. Further, in this biphasic sample, the electronic conduction transport might be governed by the mayenite minor phase due to its large defect nature and concentration compared to celite. In oxidizing conditions, the activation energy for electrical conduction was 1.42 eV, which is somewhat higher than that observed by other authors in mayenite single phase; this result was explained by taking into account the coexistence of biphasic material and an actual chemical defect scenario in SMCM is discussed

In situ drug release measuring in α-TCP cement by electrochemical impedance spectroscopy

The use of drug delivery systems is a good technique to leave the right quantity of medicine in the patient’s body in a suitable dose, because the drug application is delivered directly to the affected region. The current techniques such as HPLC and UV–Vis for the drug delivery calculation has some disadvantages, as the accuracy and the loss of the sample after characterization. With the aim of reducing the amount of material used during the characterization and have a nondestructive test with instantaneous results, the present paper shows the possibility of using electrochemical impedance spectroscopy (EIS) to have a drug delivery measurement during the release phenomena for a calcium phosphate cement (CFC) delivery system with gentamicin sulfate (GS) and lidocaine hydrochloride (LH), at a ratio of 1% and 2%, respectively. The equivalent circuit and the chemical mechanism involved during the measurements have been proposed as a tool to determine the drug delivery profile. The method has been compared with the UV–Vis technique. XRD was realized to verify conditions, before and after release. It was possible to verify the potential for using EIS as an instant technique to quantify drug delivery

Impact of wind variation on the measurement of wind turbine inertia provision

Wind turbine (WT) control is being adapted to enable inertia provision that supports network frequency on short timescales. Measuring the inertia contribution from wind turbines is critical to asses the provision of the service as well as understand the WT operation. However, inertia measurement methods disagree on the impact of the wind and how to approximate its effects. This paper uses data from a Scottish Power Renewables (SPR) test of a grid connected wind farm to highlight that wind can impact inertia provision and that external network power measurements are unable to measure the inertia. Two proposals are made to improve inertia measurements. First, the International Electrotechnical Commission (IEC) industrial standard for WT inertia measurement is adapted, and secondly, an alternate method using system identification is proposed that considers characteristics of the WT's dynamic response. The measurement methods from the literature and the proposals are assessed using the output of time-domain WT models to find the sensitivity of their accuracies to variations in the wind, frequency, and control-setting conditions. The methods from the literature are inaccurate during variable wind conditions but the proposed approaches improve the accuracy. The findings of the sensitivity study are then validated by applying the measurement methods to the SPR wind farm experimental data and confirm that the proposed system identification method is the most accurate measurement approach

Serum levels of S100B from jugular bulb as a biomarker of poor prognosis in patients with severe acute brain injury

Aims/background To evaluate the correlation between protein S100B concentrations measured in the jugular bulb as well as at peripheral level and the prognostic usefulness of this marker. Methods A prospective study of all patients admitted to the intensive care unit with acute brain damage was carried out. Peripheral and jugular bulb blood samples were collected upon admission and every 24 h for three days. The endpoints were brain death diagnosis and the Glasgow Outcome Scale score after 6 months. Results A total of 83 patients were included. Jugular protein S100B levels were greater than systemic levels upon admission and also after 24 and 72 h (mean difference > 0). Jugular protein S100B levels showed acceptable precision in predicting brain death both upon admission [AUC 0.67 (95% CI 0.53?0.80)] and after 48 h [AUC 0.73 (95% CI 0.57?0.89)]. Similar results were obtained regarding the capacity of jugular protein S100B levels upon admission to predict an unfavourable outcome (AUC 0.69 (95% CI 0.56?0.79)). The gradient upon admission (jugular-peripheral levels) showed its capacity to predict the development of brain death [AUC 0.74 (95% CI 0.62?0.86)] and together with the Glasgow Coma Scale constituted the independent factors associated with the development of brain death. Conclusion Regional protein S100B determinations are higher than systemic determinations, thus confirming the cerebral origin of protein S100B. The transcranial protein S100B gradient is correlated to the development of brain death.This study has been supported by grants from the Marqués de Valdecilla Foundation - IFIMAV (API 10/02) and the Spanish Ministry of Science - Carlos III Health Institute (PI080058). The protein S100B electrochemoluminescence assay kits were a generous donation from Roche Diagnostics, Mannheim, Germany The authors report no conflicts of interest. The authors alone are responsible for the contents and writing of the paper

Exploring an impedance-based SCR for accurate representation of grid-forming converters

The strength of an electrical network connection point is often characterized by the short circuit ratio. Analysis of the fault current contribution at the node can provide information on system impedance, voltage stability, maximum power transfer and system recovery time. However, the introduction of more power converter connected generation decreases the validity of the current short circuit ratio definition. Mainly, the parameters that determine the strength of a connection point cannot be inferred from the fault level contribution. This article presents a discussion on the pitfalls of quantifying the strength of an electrical network using fault current contribution. The limitations of the method for converter dominated networks are presented and alternative definitions from literature are discussed with drawbacks explored. Further considerations for a new index are described, and the article suggests utilizing system impedances for investigation of different stability components. Varying converter control algorithms are explored in terms of impedance, both grid-following and grid-forming. Grid-forming structures without a current loop were found to provide the greatest improvement in voltage stiffness

CARACTERIZAÇÃO MICROBIOLÓGICA DO PROCESSO DE COMPOSTAGEM DE RESÍDUOS ORGÂNICOS EM PEQUENA ESCALA

O aproveitamento dos resíduos orgânicos, como adubo para a produção agrícola, requer conhecimentos que possibilitem a adequada forma de prepará-los e que garantam um produto estabilizado e de boa qualidade. Objetivou-se realizar a caracterização da microbiota responsável pela estabilização da matéria orgânica submetida ao processo de minicompostagem, além de relacionar a presença dos grupos e indicadores microbianos (bactérias, fungos e actinobactérias, coliformes totais e Escherichia coli) com a evolução do composto. Foi possível detectar a presença dos indicadores Coliformes Totais e E.coli em todos os dias monitorados do processo de minicompostagem. Observou-se que a densidade das bactérias heterotróficas, no período de 45 dias do processo de minicompostagem, apresentou-se na faixa de 1,6 x 107a > 3,0 x 107 unidades formadoras de colônias/grama (UFC.g-1) de composto. As actinobactérias apresentaram-se na faixa de 1,0 x 106 a 1,8 x 107 UFC.g-1de composto analisado e a contagem dos fungos totais apresentou-se na faixa de 10,0 x 106 a 8,3 x 107 UFC.g-1 de composto analisado. Concluiu-se que a densidade do grupo das bactérias heterotróficas, apesar de inicialmente estar abaixo dos fungos totais, se manteve superior a densidade das bactérias actinobactérias e fungos totais

Genetic diversity and structure of Iberian Peninsula cowpeas compared to world-wide cowpea accessions using high density SNP markers

Cowpea (Vigna unguiculata L. Walp) is an important legume crop due to its high protein content, adaptation to heat and drought and capacity to fix nitrogen. Europe has a deficit of cowpea production. Knowledge of genetic diversity among cowpea landraces is important for the preservation of local varieties and is the basis to obtain improved varieties. The aims of this study were to explore diversity and the genetic structure of a set of Iberian Peninsula cowpea accessions in comparison to a worldwide collection and to infer possible dispersion routes of cultivated cowpea.This study was supported by EUROLEGUME project. This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 613781. European Investment Funds by FEDER/COMPETE/ POCI – Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT – Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013. MMA was partially supported by the Feed the Future Innovation Lab for Climate Resilient Cowpea (USAID Cooperative Agreement AID-OAA-A-13-00070), which is directed by TJC. The funding entities had no role in the design of the study, collection, analysis and interpretation of data, or in writing the manuscript.info:eu-repo/semantics/publishedVersio

Evaluating stress responses in cowpea under drought stress

Drought impact on plants is an increasing concern under the climate change scenario. Cowpea (Vigna unguiculata L. Walp.) is considered as one of the most tolerant legume crops to drought, being the search for the best well-adapted genotypes crucial to face the future challenges. Different approaches have been used for differentiating plant responses to drought stress. Plants of four cowpea genotypes were submitted to three watering regimens (a severe and moderate drought stress, and well-watered control) during 15 days, and several physiological, biochemical and molecular parameters were evaluated. Stressed plants revealed commonly-described drought stress characteristics, but not all assayed parameters were useful for discriminating plants with different drought severities or genotypes. The analyses which have contributed most to genotype discrimination were those related with stomatal function, and biochemical markers such as proline and anthocyanin contents. Antioxidant enzymes activities and related genes expression did not differed among genotypes or upon drought stress treatments, suggesting that scavenging enzymes are not involved in the differential ability of cowpea plants to survive under drought stress. This information will be useful to evaluate and use genetic resources, as well as design strategies for breeding cowpea resistance to drought stress.This study was supported by EUROLEGUME project. This project has received funding from: the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 613781; National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2019; and the project PEstOE/BIA/UI4046/2014; UID/MULTI/04046/2013