Reálná molekulární vizualizace v hodinách fyziky a chemie na základních a středních školách

The present article describes the potential use of molecular projection in chemistry and physics lessons. Beginnig of the text we point to the students´ Spatial imagination of students and the advantages of the real and computer molecular projection are discussed. Practical experience, ideas for work with molecular construction sets and several worksheets for students are added. © 2014, Czech Society of Chemical Engineering. All rights reserved

The Possible Role of Resource Requirements and Academic Career-Choice Risk on Gender Differences in Publication Rate and Impact

Many studies demonstrate that there is still a significant gender bias, especially at higher career levels, in many areas including science, technology, engineering, and mathematics (STEM). We investigated field-dependent, gender-specific effects of the selective pressures individuals experience as they pursue a career in academia within seven STEM disciplines. We built a unique database that comprises 437,787 publications authored by 4,292 faculty members at top United States research universities. Our analyses reveal that gender differences in publication rate and impact are discipline-specific. Our results also support two hypotheses. First, the widely-reported lower publication rates of female faculty are correlated with the amount of research resources typically needed in the discipline considered, and thus may be explained by the lower level of institutional support historically received by females. Second, in disciplines where pursuing an academic position incurs greater career risk, female faculty tend to have a greater fraction of higher impact publications than males. Our findings have significant, field-specific, policy implications for achieving diversity at the faculty level within the STEM disciplines.Comment: 9 figures and 3 table

Сравнение радиационного загрязнения почв с физиологическими параметрами развития тестовых растений на объектах Cухачевской промплощадки

Целью работы было проведение оценки влияния хранилища урановой руды «База С» и хвостохранилища «Сухачевское» на физиологические параметры развития тестовых растений. Приведено содержание природных и техногенных радионуклидов, мощности экспозиционной дозы гамма-излучения в местах их произрастания. Концентрацию радионуклидов U²³⁸ , Th²³⁰, Ra²²⁶, Pb²¹⁰, Th²³², K⁴⁰ и Cs¹³⁷ определяли с помощью низко-фонового полупроводникового HРGe гамма-спектрометра с детектором GMХ40 ORTEC, мощность эквивалентной дозы гамма-излучения измеряли с помощью дозиметра ДКС 97. Представлены результаты сравнения радиационного загрязнения почв с физиологическими параметрами развития тестовых растений. Не установлена корреляция уровня повреждения биоиндикатора с мощностью экспозиционной дозы гамма-излучения и удельной активностью радионуклидов.Метою роботи було проведення оцінки впливу сховища уранової руди «База С» та хвостосховища «Сухачівське» на фізіологічні параметри розвитку тестових рослин. Приведено вміст природних та техногенних радіонуклідів, потужності експозиційної дози гамма-випромінювання в місцях їх виростання. Концентрацію радіонуклідів U238, U²³⁸, Th²³⁰, Ra²²⁶, Pb²¹⁰, Th²³², K⁴⁰ і Cs¹³⁷ визначали за допомогою низько-фонового напівпроводникового HРGe гамма-спектрометра з детектором GMХ40 ORTEC, потужність еквівалентної дози гамма-випромінювання вимірювали за допомогою дозиметра ДКС 97. Наведено результати порівняння радіаційного забруднення ґрунтів з фізіологічними параметрами розвитку тестових рослин. Не встановлена кореляція рівня ушкодження біоіндикатору з потужністю експозиційної дози гамма-випромінювання та питомою активністю радіонуклідів.The work aimed to assess the impact of Baza S uranium ore storage site and Sukhachevskoye uranium mill tailing impoundment on physiological parameters of the test plant morphosis. The content of natural and man-induced radio nuclides is given as well as exposure dose rate at the places of their growing. U²³⁸, Th²³⁰, Ra²²⁶, Pb²¹⁰, Th²³², K⁴⁰ and Cs¹³⁷ concentrations were measured using HРGe low-background semi-conductor gamma-spectrometer with GMХ40 ORTEC detector, exposure dose rate of gamma radiation was measured using DKS 97 dosimeter. The paper presents the data on the soil radioactive contamination with physiological parameters of the test plant morphosis. No correlation was established between the bioindicator damage level, exposure dose of gamma radiation and radionuclide specific activity

Multi-scale magnetic nanoparticle based optomagnetic bioassay for sensitive DNA and bacteria detection

Benefiting from their rapid readout, highly flexible devices and low-cost portable systems, optomagnetic biosensors have drawn increased attention in recent years as bioassay technologies for small molecules, biomarkers, DNA, and bacteria. Herein, an optomagnetic bioassay strategy suitable for point-of-care diagnostics, utilizing functionalized magnetic nanoparticles (100 nm) with Brownian relaxation behavior is optimized in order to obtain higher detection sensitivity for DNA molecules and bacteria. Presence of target DNA sequences or bacteria changes the dynamic behavior of the magnetic nanoparticles (binding to the target) and thus the optomagnetic response of the sample, which is measured by an optomagnetic setup including a 405 nm laser and a photodetector. The limit of detection is mainly set by the lowest measurable concentration of magnetic nanoparticles. Herein, as new results compared to previous work, we systematically optimize the concentration of 100 nm magnetic nanoparticles to increase the assay sensitivity and lower the limit of detection. To enable biplex detection, we perform this optimization in the presence of larger 250 nm magnetic nanoparticles that do not interact with the target. We show that the optimization and lowering of the 100 nm magnetic nanoparticle concentration result in a limit of detection of 780 fM of DNA coils formed by rolling circle amplification (size of about 1 mu m) and 10(5) CFU per mL Salmonella (for immunoassay). These values are 15 times lower than those reported previously for this readout principle. Finally, we show that the 250 nm magnetic nanoparticles can serve as a second detection label for qualitative biplex detection of DNA coils formed by rolling circle amplification from V. cholerae and E. coli DNA coils using 100 nm and 250 nm magnetic detection nanoparticles, respectively

A Substance Flow Model for Global Phosphorus

A mechanistic model of phosphorus flows through the global food system was developed to address questions about the relative effectiveness of and interactions among potential conservation interventions. Phosphorus is required as a fertilizer for producing food, and there is no substitute. Most phosphorus used in agriculture is mined, and 75% of the world’s reserves are controlled by a single country: Morocco. Thus the world’s food supply is potentially vulnerable to geopolitical conditions. Although known reserves can satisfy current demand for several centuries, it is nevertheless the case that an essential resource is being used unsustainably. Only about 10% of the phosphorus used in agriculture reaches our plates. Losses along the way contribute to water pollution, causing eutrophication. In freshwater bodies this produces toxic drinking water and fish kills. In the coastal marine environment eutrophication causes hypoxic (low oxygen) zones, popularly called “dead zones, in many parts of the world. Thus conservation of phosphorus is of interest both to preserve the resource and to prevent pollution. The conservation interventions considered include: population control; reduction in meat fraction in the diet (MFD); animal manure use efficiency (MUE); agricultural phosphorus use efficiency (PUE); the fraction of food supply that is wasted; the fraction of food waste that is recycled; the fraction of human waste that is recycled. The model shows that the meat fraction in the diet is the most sensitive of these factors, and this factor interacts with PUE and MUE. Furthermore, there is a minimum MFD below which it actually becomes necessary to mine more phosphorus. Another conclusion is that recycling is much less effective than reduction in conserving the resource