Semiconductor Gas Sensors: Materials, Technology, Design, and Application

This paper presents an overview of semiconductor materials used in gas sensors, their technology, design, and application. Semiconductor materials include metal oxides, conducting polymers, carbon nanotubes, and 2D materials. Metal oxides are most often the first choice due to their ease of fabrication, low cost, high sensitivity, and stability. Some of their disadvantages are low selectivity and high operating temperature. Conducting polymers have the advantage of a low operating temperature and can detect many organic vapors. They are flexible but affected by humidity. Carbon nanotubes are chemically and mechanically stable and are sensitive towards NO and NH3, but need dopants or modifications to sense other gases. Graphene, transition metal chalcogenides, boron nitride, transition metal carbides/nitrides, metal organic frameworks, and metal oxide nanosheets as 2D materials represent gas-sensing materials of the future, especially in medical devices, such as breath sensing. This overview covers the most used semiconducting materials in gas sensing, their synthesis methods and morphology, especially oxide nanostructures, heterostructures, and 2D materials, as well as sensor technology and design, application in advance electronic circuits and systems, and research challenges from the perspective of emerging technologies. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Chemical Composition, Antioxidant, and Antimicrobial Activities of Lichen Umbilicaria cylindrica (L.) Delise (Umbilicariaceae)

The phytochemical analysis of methanol and chloroform extracts of Umbilicaria cylindrica was determined by HPLC-UV method. The predominant phenolic compound in both extracts was depsidone, salazinic acid (1). Besides salazinic acid, the tested extracts of U. cylindrica contain norstictic acid (2), methyl-β-orcinol carboxylate (3), ethyl haematommate (4), atranorin (5), and usnic acid (6), in different amounts and relations. The lichen extracts showed comparable and strong antioxidant activity, exhibited higher DPPH and hydroxyl radical scavengings, chelating activity, and inhibitory activity towards lipid peroxidation. The lichen extracts demonstrated important antimicrobial activity against eight strains with MIC values from 15.62 to 62.50 μg/mL. This is the first report of the detail chemical composition and antioxidant activity of the lichen Umbilicaria cylindrica, and the results suggest that this lichen can be used as a new source of the natural antioxidants and the substances with antimicrobial features

Співвідношення навчання і виховання у філософії педагогіки Памфіла Юркевича

24th General Meeting of the European-Grassland-Federation -- JUN 03-07, 2012 -- Lublin, POLANDWOS: 000361159300041Italian ryegrass monoculture and mixtures with red clover (sowing ratios 75:25%, 50:50% and 25:75%) were established in the spring of 2008 at the Institute for Animal Husbandry, Belgrade, with the aim to analyse the possibilities of managing the N supply. There were four N rates for Italian ryegrass monoculture: 0, 100, 150 and 200 kg ha(-1), whilst no N fertilizer was applied to the mixture plots. The trial was carried out during 2008-2010 and the highest total DM yield was obtained with 200 kg N ha(-1), similar to that of the ryegrass-clover mixtures. Ryegrass contributed less to the total yield in the mixtures, because it had lower ratios in the structure of swards than those used at sowing. An Italian ryegrass-red clover sward may have advantages over a pure Italian ryegrass sward fertilized by high rates of N, providing high yield with a more sustainable land-use system.Kuhn, Ministerstwo Rolnictwa Rozwoju Wsi, Lubelski Wegiel Bogdanka S A, Karol Kania Synowie, Rolimpex, Dept Rolnictwa Srodowiska Urzedu Marszalkowskiego Wojewodztwa, Lubelskiego, Linia Hutnicza Szerokotorowa, Powiat Bilgorajski, Centinas, DSV Polska, Perla Browary Lubelskie, Lubella, Uniwersytet Przyrodniczy w Lublinie, Miasto Lublin, Apis, Herbapol Lublin S A, OSM Krasnystaw, Powiat Krasnostawski, Powiat Lubelski, Powiat Krasnystaw, Lubelska Izba Rolnicza, Gmina Krasnystaw, Urzad Miasta Krasnysta

Delayed Care and Mortality Among Women and Men with Myocardial Infarction

Background-Women with ST-segment-elevation myocardial infarction (STEMI) have higher mortality rates than men. We investigated whether sex-related differences in timely access to care among STEMI patients may be a factor associated with excess risk of early mortality in women. Methods and Results-We identified 6022 STEMI patients who had information on time of symptom onset to time of hospital presentation at 41 hospitals participating in the ISACS-TC (International Survey of Acute Coronary Syndromes in Transitional Countries) registry (NCT01218776) from October 2010 through April 2016. Patients were stratified into time-delay cohorts. We estimated the 30-day risk of all-cause mortality in each cohort. Despite similar delays in seeking care, the overall time from symptom onset to hospital presentation was longer for women than men (median: 270 minutes [range: 130-776] versus 240 minutes [range: 120-600]). After adjustment for baseline variables, female sex was independently associated with greater risk of 30-day mortality (odds ratio: 1.58; 95% confidence interval, 1.27-1.97). Sex differences in mortality following STEMI were no longer observed for patients having delays from symptom onset to hospital presentation of (odds ratio: 0.77; 95% confidence interval, 0.29-2.02). Conclusions-Sex difference in mortality following STEMI persists and appears to be driven by prehospital delays in hospital presentation. Women appear to be more vulnerable to prolonged untreated ischemia

Aspirin for primary prevention of ST segment elevation myocardial infarction in persons with diabetes and multiple risk factors

Controversy exists as to whether low-dose aspirin use may give benefit in primary prevention of cardiovascular (CV) events. We hypothesized that the benefits of aspirin are underevaluated. We investigated 12,123 Caucasian patients presenting to hospital with acute coronary syndromes as first manifestation of CV disease from 2010 to 2019 in the ISACS-TC multicenter registry (ClinicalTrials.gov, NCT01218776). Individual risk of ST segment elevation myocardial infarction (STEMI) and its association with 30-day mortality was quantified using inverse probability of treatment weighting models matching for concomitant medications. Estimates were compared by test of interaction on the log scale. The risk of STEMI was lower in the aspirin users (absolute reduction: 6·8%; OR: 0·73; 95%CI: 0·65-0·82) regardless of sex (p for interaction=0·1962) or age (p for interaction=0·1209). Benefits of aspirin were seen in patients with hypertension, hypercholesterolemia, and in smokers. In contrast, aspirin failed to demonstrate a significant risk reduction in STEMI among diabetic patients (OR:1·10;95%CI:0·89-1·35) with a significant interaction (p: <0·0001) when compared with controls (OR:0·64,95%CI:0·56-0·73). Stratification of diabetes in risk categories revealed benefits (p interaction=0·0864) only in patients with concomitant hypertension and hypercholesterolemia (OR:0·87, 95% CI:0·65-1·15), but not in smokers. STEMI was strongly related to 30-day mortality (OR:1·93; 95%CI:1·59-2·35) Low-dose aspirin reduces the risk of STEMI as initial manifestation of CV disease with potential benefit in mortality. Patients with diabetes derive substantial benefit from aspirin only in the presence of multiple risk factors. In the era of precision medicine, a more tailored strategy is required

Genomics-Based Insights Into the Biosynthesis and Unusually High Accumulation of Free Fatty Acids by Streptomyces sp NP10

Schneider O, Ilic-Tomic T, Rückert C, et al. Genomics-Based Insights Into the Biosynthesis and Unusually High Accumulation of Free Fatty Acids by Streptomyces sp NP10. FRONTIERS IN MICROBIOLOGY. 2018;9: 10.Streptomyces sp. NP10 was previously shown to synthesize large amounts of free fatty acids (FFAs). In this work, we report the first insights into the biosynthesis of these fatty acids (FAs) gained after genome sequencing and identification of the genes involved. Analysis of the Streptomyces sp. NP10 draft genome revealed that it is closely related to several strains of Streptomyces griseus. Comparative analyses of secondary metabolite biosynthetic gene clusters, as well as those presumably involved in FA biosynthesis, allowed identification of an unusual cluster C12-2, which could be identified in only one other S. griseus-related streptomycete. To prove the involvement of identified cluster in FFA biosynthesis, one of its three ketosynthase genes was insertionally inactivated to generate mutant strain mNP10. Accumulation of FFAs in mNP10 was almost completely abolished, reaching less than 0.01% compared to the wild-type strain. Cloning and transfer of the C12-2 cluster to the mNP10 mutant partially restored FFA production, albeit to a low level. The discovery of this rare FFA biosynthesis cluster opens possibilities for detailed characterization of the roles of individual genes and their products in the biosynthesis of FFAs in NP10

Magnesium substitution with nickel and its influence on the sensing properties of MgFe2O4

Mixed spinel ferrites MgxNi1-xFe2O4 were synthesized via sol-gel combustion synthesis with citric acid as fuel, followed by calcination at 700 °C for 3 hours. Obtained powders were characterized via X-ray diffraction analysis (XRD), X-ray photoelectron (XPS), FTIR and Raman spectroscopy and FESEM microscopy. Elemental composition was examined via energy dispersive spectroscopy (EDS). Humidity sensing properties were tested by measuring AC impedance in a climactic chamber at 25 °C and in the relative humidity range of 40–90%. Temperature sensing properties were tested by measuring DC resistance at 40% RH in the temperature range 40–90 °C. Synthesized powders were proven to be pure spinel Fd 3m phase with spherical, slightly agglomerated particles. Substitution of Mg with Ni results in structural changes such as a change in inversion parameter and particle agglomeration, which influences sensing properties of the material. Results show that the sensing properties of magnesium ferrite can be improved by incorporating 10% of nickel in the spinel lattice structure. Mg0.9Ni0.1Fe2O4 exhibited higher temperature sensitivity and higher sensitivity towards humidity compared to MgFe2O4, while further substitution of Mg with Ni resulted in the decline of sensing properties, increase in particle size and agglomeration degree

INFLUENCE OF CALCINATION TEMPERATURE ON THE STRUCTURE, MORPHOLOGY AND OPTICAL PROPERTIES OF ELECTROSPUN PSEUDOBROOKITE NANOFIBERS

Novel crystalline iron-titanate fibers were synthesized for the first time to the best of our knowledge, through a simple, low cost electrospinning method followed by calcination treatment at different temperatures (500–750 °C for 3 h and at 500 °C for 6 h and at 550 °C for 4 h). The fibers were prepared from a precursor solution containing polyvinylpyrrolidone (PVP), iron(III) nonahydrate, titanium isopropoxide, N,N-Dimethylformamide and ethanol. As spun fibers were smooth, straight, beadless and uniform forming a nonwoven fibrous mat, with an average diameter of ca. 205 nm. Upon calcination in air the PVP matrice was removed and XRD and FTIR analysis showed that the duration of the calcination process, besides the temperature, had a direct influence on phase formation. Pure phase of pseudobrookite was obtained at 600 °C, 500 °C for 6 h and at 550 °C for 4 h. In addition, the morphology of obtained nanofibers was directly affected by the calcination temperature. The surface of fibers obtained after calcination was no longer smooth and the fiber diameter decreased due to complete degradation of PVP. At 700 oC and 750 °C, fibers were thicker which can be attributed to growth of Fe2TiO5 nanoparticles and simultaneous coalescence of small particles. All samples exhibited a type IV nitrogen adsorption isotherm with a type- H3 indicating slit-shaped mesoporous structure. The BET surface areas of 500 oC for 6 h, 550 oC for 4 h and 600 oC for 3 h were estimated to be 62, 38.7 and 33.2 m2/g, respectively