440 research outputs found

    Wavepacket insights into the photoprotection mechanism of the UV filter methyl anthranilate

    Get PDF
    Meradimate is a broad-spectrum ultraviolet absorber used as a chemical filter in commercial sunscreens. Herein, we explore the ultrafast photodynamics occurring in methyl anthranilate (precursor to Meradimate) immediately after photoexcitation with ultraviolet radiation to understand the mechanisms underpinning Meradimate photoprotection. Using time-resolved photoelectron spectroscopy, signal from the first singlet excited state of methyl anthranilate shows an oscillatory behavior, i.e. quantum beats. Our studies reveal a dependence of the observed beating frequencies on photoexcitation wavelength and photoelectron kinetic energy, unveiling the different Franck-Condon overlaps between the vibrational levels of the ground electronic, first electronic excited, and ground cationic states of methyl anthranilate. By evaluating the behavior of these beats with increasing photon energy, we find evidence for intramolecular vibrational energy redistribution on the first electronic excited state. Such energy redistribution hinders efficient relaxation of the electronic excited state, making methyl anthranilate a poor choice for an efficient, efficacious sunscreen chemical filter

    Ultrafast dissociation dynamics of 2-Ethylpyrrole

    Get PDF
    To explore the effects of ring substitution on dissociation dynamics, the primary photochemistry of 2-ethylpyrrole has been explored using ultrafast ion imaging techniques. Photoexcitation to the S1 state, a πσ* state, in the range of 238 to 265 nm results in cleavage of the N–H bond with an H-atom appearance lifetime of ca. 70 fs. The insensitivity of this lifetime to photon energy, combined with a small kinetic isotope effect, suggests that tunneling does not play a major role in N–H bond cleavage. Total kinetic energy release spectra reveal modest vibrational excitation in the radical counter-fragment, increasing with photon energy. At wavelengths ≤ 248 nm a second, low kinetic energy H-atom loss mechanism becomes available with an appearance lifetime of approximately 1.5 ps and possibly due to the population of higher lying 1ππ* states

    Do saving promotion interventions help alleviate poverty in Sub-Saharan Africa? A systematic review and meta-analysis

    Full text link
    Saving promotion interventions have gained momentum in international development over the recent years. Our analysis investigates whether saving promotion can effectively reduce poverty and economic hardship in Sub-Saharan Africa. In an extensive database search, 9330 records were screened and 27 randomised controlled trials on saving promotion interventions fulfilled the inclusion criteria. Robust-variance estimations of pooled effect sizes show small but significant impacts on poverty reduction, including increases in household expenditures and incomes, higher returns from family businesses, and improved food security. They also show positive impacts on more intermediate outcomes including total savings, pro-saving attitudes, financial literacy, and investments in small-scale family businesses. Our results do not show significant effects on assets, housing quality, education, or health. Findings from this analysis suggest that saving promotion schemes are highly relevant in reducing poverty in Sub-Saharan Africa, and that formal banking services in particular require adaptation to the needs of the poor

    Validation of Aura Microwave Limb Sounder O-3 and CO observations in the upper troposphere and lower stratosphere

    Get PDF
    International audienceGlobal satellite observations of ozone and carbon monoxide from the Microwave Limb Sounder (MLS) on the EOS Aura spacecraft are discussed with emphasis on those observations in the 215–100 hPa region (the upper troposphere and lower stratosphere). The precision, resolution and accuracy of the data produced by the MLS “version 2.2” processing algorithms are discussed and quantified. O3 accuracy is estimated at ~40 ppbv +5% (~20 ppbv +20% at 215 hPa) while the CO accuracy is estimated at ~30 ppbv +30% for pressures of 147 hPa and less. Comparisons with expectations and other observations show good agreements for the O3 product, generally consistent with the systematic errors quoted above. In the case of CO, a persistent factor of ~2 high bias is seen at 215 hPa. However, the morphology is shown to be realistic, consistent with raw MLS radiance data, and useful for scientific study. The MLS CO data at higher altitudes are shown to be consistent with other observations

    “Bibliostory—Educational Comic Stories.” A Social Constructivist Approach to Media and Information Literacy Education for Children and Adolescents

    Get PDF
    Our paper presents a theoretical background for a Polish comic book “Bibliostory—educational comic stories” (Pl. Bibliostory—edukacyjne historie komiksowe). The comic targets children between 9 and 12 years of age and youths from 13 to 16 years of age. Each story illustrates one issue, such as information searching, organization of information, plagiarism, and information problem solving strategy. Bibliostory is based on two constructivist pedagogical concepts: the zone of proximal development (ZPD) and case-based learning/teaching. These concepts, on application level, are first of all associated with designing educational situations and relationships between teachers and students (educators and learners). The aim of our paper is to present the possibilities of application of these concepts in the educational comic books. We describe the general assumptions of two concepts, then we focus on elements applied in Bibliostory project. We also provide a review of literature on the educational potential of comic books.Zuza Wiorogórska’s work was carried out during her stay as the visiting scholar at the University of California, Berkeley, thanks to a scholarship from the Kosciuszko Foundation. Ewa Rozkosz’s work was carried out thanks to the grant awarded by the Faculty of Education of the University of Lower Silesia for the project “Społeczno-kulturowe podejście w projektowaniu materiałów edukacyjnych na potrzeby edukacji medialnej I inforamacyjnej dzieci i młodzieży na przykładzie »Bibliostory«” (nr 05/ WGW/dok/2016)

    Wartość prognostyczna scyntygrafii perfuzyjnej mięśnia sercowego metodą SPECT z użyciem 99mTc-MIBI w grupie pacjentów po przebytym w przeszłości zawale serca

    Get PDF
    Introduction. Data describing prognostic utility of SPECT (single-photon emission computed tomography) among patients with history of myocardial infarction (MI) is scarce. We aimed to compare prognostic value of SPECT scans in patients with vs. without history of myocardial infarction (MI) prior to perfusion imaging. Material and methods. 151 consecutive patients with history of myocardial infarction, who underwent exercise 99mTc-MIBI SPECT examination were enrolled in the study (group 1). Next, based on clinical and demographic baseline characteristics, SPECT result and duration of follow-up period, a matching control subgroup (group 2) of 151 patients without history of MI was formed. During a mean follow-up of 60 ± 15 months in group 1 and a mean follow-up of 60 ± 13.5 months in group 2, we analyzed prevalence of cardiovascular events rates (cardiac deaths, myocardial infarctions and cardiac revascularizations). Results. We observed the following rates of cardiac deaths, myocardial infarctions and cardiac revascularizations: 4%, 15% and 26%, respectively in group 1 and 1%, 13% and 17%, respectively in group 2. In patients without history of MI (group 2) presence of mixed perfusion defects on SPECT was associated with significantly higher rate of myocardial infarctions (p = 0.05), hospitalizatons (p = 0.0001) and revascularizations (p = 0.0002). Fixed perfusion defects were associated with significantly higher occurrence of deaths (p = 0.012) and hospitalizations (p = 0.02), but not myocardial infarctions (p = 0.52) or cardiac revascularizations (p = 0.10). In contrast, among patients with history of MI (group 1) there was no statistically significant relationship between any type of perfusion defects and cardiovascular events. Conclusions. Long term follow-up demonstrates that prognostic value of 99mTc-MIBI SPECT is different in patients with and without history of MI.Wstęp. W dostępnej literaturze brakuje badań służących ocenie przydatności prognostycznej scyntygrafii perfuzyjnej mięśnia sercowego SPECT (tomografia emisyjna pojedynczego fotonu) w grupie chorych z wywiadem przebytego zawału serca. Celem opisanego badania jest porównanie wartości prognostycznej SPECT w grupie pacjentów z wywiadem zawału serca przed badaniem SPECT oraz bez takiego wywiadu. Materiał i metody. Do badania włączono 151 kolejnych pacjentów z wywiadem zawału serca, u których wykonano badanie SPECT z użyciem 99mTc-MIBI. Następnie, na podstawie charakterystyki klinicznej i demograficznej oraz długości okresu obserwacji dobrano, grupę kontrolną 151 pacjentów poddanych badaniu SPECT, bez wywiadu wcześniejszego zawału serca. Wyniki. Po średnim okresie obserwacji 60 ± 15 miesięcy (grupa 1) i 60 ± 13,5 miesiąca (grupa 2) częstość wystąpienia punktów końcowych, takich jak zgon z przyczyn sercowo-naczyniowych, zawał serca, rewaskularyzacja, wyniosła odpowiednio 4%, 15% i 26% w grupie 1 oraz 1%, 13%, 17% w grupie 2. Wśród pacjentów bez wywiadu zawału serca (grupa 2) obecność mieszanych zaburzeń perfuzji w badaniu SPECT wiązała się z istotnie większą częstością zawałów serca (p =0,05), hospitalizacji (p = 0,0001) oraz rewaskularyzacji (p = 0,0002). Utrwalone zaburzenia perfuzji wiązały się z istotnie większą liczbą zgonów z przyczyn sercowo-naczyniowych, liczbą hospitalizacji (p=0,02), ale nie zawałów serca (p = 0,52) ani rewaskularyzacji (p = 0,10). Natomiast wśród pacjentów bez wywiadu zawału serca (grupa 1) nie zaobserwowano istotnej statystycznie zależności między typem zaburzeń perfuzji a występowaniem powyższych punktów końcowych. Wnioski. W długoterminowej obserwacji wykazano różnicę w zakresie wartości rokowniczej badania SPECT między pacjentami po przebytym zawale serca oraz bez wywiadu zawału

    Expiratory flow rate, breath hold and anatomic dead space influence electronic nose ability to detect lung cancer

    Get PDF
    BACKGROUND: Electronic noses are composites of nanosensor arrays. Numerous studies showed their potential to detect lung cancer from breath samples by analysing exhaled volatile compound pattern ("breathprint"). Expiratory flow rate, breath hold and inclusion of anatomic dead space may influence the exhaled levels of some volatile compounds; however it has not been fully addressed how these factors affect electronic nose data. Therefore, the aim of the study was to investigate these effects. METHODS: 37 healthy subjects (44 +/- 14 years) and 27 patients with lung cancer (60 +/- 10 years) participated in the study. After deep inhalation through a volatile organic compound filter, subjects exhaled at two different flow rates (50 ml/sec and 75 ml/sec) into Teflon-coated bags. The effect of breath hold was analysed after 10 seconds of deep inhalation. We also studied the effect of anatomic dead space by excluding this fraction and comparing alveolar air to mixed (alveolar + anatomic dead space) air samples. Exhaled air samples were processed with Cyranose 320 electronic nose. RESULTS: Expiratory flow rate, breath hold and the inclusion of anatomic dead space significantly altered "breathprints" in healthy individuals (p 0.05). These factors also influenced the discrimination ability of the electronic nose to detect lung cancer significantly. CONCLUSIONS: We have shown that expiratory flow, breath hold and dead space influence exhaled volatile compound pattern assessed with electronic nose. These findings suggest critical methodological recommendations to standardise sample collections for electronic nose measurements

    Ratios rather than concentrations of nutritionally important elements may shape honey bee preferences for ‘dirty water’

    Get PDF
    1. Honey bees require minerals for a complete diet. However, minerals from flowers can be inadequate in concentration and composition. Therefore, honey bees may drink ‘dirty water’ from natural sources such as puddles. Some research has attempted to simulate this through honey bee bioassays, but to date, these have tested minerals individually, not as mixtures as would occur in nature. Here, for the first time, we use honey bees in bioassays in which a range of mineral mixtures are presented together in choice experiments. 2. Six minerals (NaCl, KCl, CaCl₂, MgCl₂, NH₄Cl, and KH₂PO₄) were used in mixtures to simulate different mineral stoichiometries, which may occur in ‘dirty water’, such as puddles, from which honey bees often drink. Based on the honey bee mineral tolerance ranges from the literature, these mixtures were offered in aqueous solutions at low, medium, high, and mixed molar concentrations. Deionised water and sucrose were neutral and positive controls, respectively. Petri dishes were set up in containers in a laboratory. Twenty worker honey bees (Apis mellifera L.) were placed into each container and observed for drinking behaviour for 1 h. 3. Honey bees preferred the mixed molar treatment comprising a high Na:K ratio, a medium molarity of NaCl and a low molarity of the other minerals. This novel finding suggests that mixed mineral ‘dirty water’ should be investigated on a larger scale with multiple hives in the field and highlights the importance of stoichiometrically balanced honey bee diets

    The chemerin knockout rat reveals chemerin dependence in female, but not male, experimental hypertension

    Full text link
    Measures of the adipokine chemerin are elevated in multiple cardiovascular diseases, including hypertension, but little mechanistic work has been done to implicate chemerin as being causative in such diseases. The chemerin knockout (KO) rat was created to test the hypothesis that removal of chemerin would reduce pressure in the normal and hypertensive state. Western analyses confirmed loss of chemerin in the plasma and tissues of the KO vs. wild‐type (WT) rats. Chemerin concentration in plasma and tissues was lower in WT females than in WT males, as determined by Western analysis. Conscious male and female KO rats had modest differences in baseline measures vs. the WT that included systolic, diastolic, mean arterial and pulse pressures, and heart rate, all measured telemetrically. The mineralocorticoid deoxycorticosterone acetate (DOCA) and salt water, combined with uninephrectomy as a hypertensive stimulus, elevated mean and systolic blood pressures of the male KO higher than the male WT. By contrast, all pressures in the female KO were lower than their WT throughout DOCA‐salt treatment. These results revealed an unexpected sex difference in chemerin expression and the ability of chemerin to modify blood pressure in response to a hypertensive challenge.—Watts, S. W., Darios, E. S., Mullick, A. E., Garver, H., Saunders, T. L., Hughes, E. D., Filipiak, W. E., Zeidler, M. G., McMullen, N., Sinal, C. J., Kumar, R. K., Ferland, D. J., Fink, G. D. The chemerin knockout rat reveals chemerin dependence in female, but not male, experimental hypertension. FASEB J. 32, 6596–6614 (2018). www.fasebj.orgPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154357/1/fsb2fj201800479.pd
    corecore