156 research outputs found
Method of calculation of electrical properties of materials based on the results of quantum-chemical calculations
The work is devoted to a literary analysis of methods for interpreting the results of quantum-chemical calculations of the electronic structure. The concept of calculating the density of electronic states on the basis of the results obtained by the Hartree-Fock method is given. The structural scheme of the software based on the constructed concept is presented
Magnetic induction processes in Hot Jupiters, application to KELT-9b
The small semi-major axes of Hot Jupiters lead to high atmospheric
temperatures of up to several thousand Kelvin. Under these conditions,
thermally ionised metals provide a rich source of charged particles and thus
build up a sizeable electrical conductivity. Subsequent electromagnetic
effects, such as the induction of electric currents, Ohmic heating, magnetic
drag, or the weakening of zonal winds have thus far been considered mainly in
the framework of a linear, steady-state model of induction. For Hot Jupiters
with an equilibrium temperature K, the induction of atmospheric
magnetic fields is a runaway process that can only be stopped by non-linear
feedback. For example, the back-reaction of the magnetic field onto the flow
via the Lorentz force or the occurrence of magnetic instabilities. Moreover, we
discuss the possibility of self-excited atmospheric dynamos. Our results
suggest that the induced atmospheric magnetic fields and electric currents
become independent of the electrical conductivity and the internal field, but
instead are limited by the planetary rotation rate and wind speed. As an
explicit example, we characterise the induction process for the hottest
exoplanet, KELT-9b by calculating the electrical conductivity along atmospheric
-profiles for the day- and nightside. Despite the temperature varying
between 3000 K and 4500 K, the resulting electrical conductivity attains an
elevated value of roughly 1 S/m throughout the atmosphere. The induced magnetic
fields are predominately horizontal and might reach up to a saturation field
strength of 400 mT, exceeding the internal field by two orders of magnitude
Global Burden of Disease of Mercury Used in Artisanal Small-Scale Gold Mining
BACKGROUND Artisanal small-scale gold mining (ASGM) is the world's largest anthropogenic source of mercury emission. Gold miners are highly exposed to metallic mercury and suffer occupational mercury intoxication. The global disease burden as a result of this exposure is largely unknown because the informal character of ASGM restricts the availability of reliable data. OBJECTIVE To estimate the prevalence of occupational mercury intoxication and the disability-adjusted life years (DALYs) attributable to chronic metallic mercury vapor intoxication (CMMVI) among ASGM gold miners globally and in selected countries. METHODS Estimates of the number of artisanal small-scale gold (ASG) miners were extracted from reviews supplemented by a literature search. Prevalence of moderate CMMVI among miners was determined by compiling a dataset of available studies that assessed frequency of intoxication in gold miners using a standardized diagnostic tool and biomonitoring data on mercury in urine. Severe cases of CMMVI were not included because it was assumed that these persons can no longer be employed as miners. Cases in workers' families and communities were not considered. Years lived with disability as a result of CMMVI among ASG miners were quantified by multiplying the number of prevalent cases of CMMVI by the appropriate disability weight. No deaths are expected to result from CMMVI and therefore years of life lost were not calculated. Disease burden was calculated by multiplying the prevalence rate with the number of miners for each country and the disability weight. Sensitivity analyses were performed using different assumptions on the number of miners and the intoxication prevalence rate. FINDINGS Globally, 14-19 million workers are employed as ASG miners. Based on human biomonitoring data, between 25% and 33% of these miners-3.3-6.5 million miners globally-suffer from moderate CMMVI. The resulting global burden of disease is estimated to range from 1.22 (uncertainty interval [UI] 0.87-1.61) to 2.39 (UI 1.69-3.14) million DALYs. CONCLUSIONS This study presents the first global and country-based estimates of disease burden caused by mercury intoxication in ASGM. Data availability and quality limit the results, and the total disease burden is likely undercounted. Despite these limitations, the data clearly indicate that mercury intoxication in ASG miners is a major, largely neglected global health problem
Expression of somatic-stem transition genes and macrophage-associated genes in breast tumor
In a study of breast cancer of 68 patients before and after neoadjuvant chemotherapy, overexpression in the residual tumor of 14/16 genes of the somato-stem transition was shown in patients with metastases that subsequently developed. This confirms our hypothesis about the important role of activation of the ability to somato-stem transition for tumor metastasis, which occurs under the influence of neoadjuvant chemotherapy. A new prognostic factor has been established, which makes it possible to predict the occurrence of hematogenous metastases with a sensitivity of 69%, a specificity of 94%, and a diagnostic accuracy of 82%
Disability Weights for Chronic Mercury Intoxication Resulting from Gold Mining Activities: Results from an Online Pairwise Comparisons Survey
Steckling N, Devleesschauwer B, Winkelnkemper J, et al. Disability Weights for Chronic Mercury Intoxication Resulting from Gold Mining Activities: Results from an Online Pairwise Comparisons Survey. International Journal of Environmental Research and Public Health. 2017;14(1): 57
Story Map for Stormwater Management Projects at the University of Maryland
Final project for INST490: Integrated Capstone for Information Science (Spring 2020). University of Maryland, College Park.Our group was tasked with retrieving and consolidating datasets/databases and
primary accounts of enhanced stormwater management projects. These facilities have
been installed across campus over time, so we needed to visualize that data through an
ArcGIS StoryMap. We included information about individuals, project descriptions
including size and/or area impacted, deliverables, projected impact, geographic
locations, and organizations. The Story Map will be used as part of an informational
website that displays why these stormwater facilities are important and how similar
facilities are necessary elsewhere on campus.Prince George's Count
No substantial changes in estrogen receptor and estrogen-related receptor orthologue gene transcription in Marisa cornuarietis exposed to estrogenic chemicals
This article is made available through the Brunel Open Access Publishing Fund. This is an open-access article distributed under the terms of the Creative
Commons Attribution-NonCommercial-No Derivative Works License, which permits
non-commercial use, distribution, and reproduction in any medium, provided
the original author and source are credited.Estrogen receptor orthologues in molluscs may be targets for endocrine disruptors, although mechanistic evidence is lacking. Molluscs are reported to be highly susceptible to effects caused by very low concentrations of environmental estrogens which, if substantiated, would have a major impact on the risk assessment of many chemicals. The present paper describes the most thorough evaluation to-date of the susceptibility of Marisa cornuarietis ER and ERR gene transcription to modulation by vertebrate estrogens in vivo and in vitro. We investigated the effects of estradiol-17β and 4-tert-Octylphenol exposure on in vivo estrogen receptor (ER) and estrogen-related receptor (ERR) gene transcription in the reproductive and neural tissues of the gastropod snail M. cornuarietis over a 12-week period. There was no significant effect (p > 0.05) of treatment on gene transcription levels between exposed and non-exposed snails. Absence of a direct interaction of estradiol-17β and 4-tert-Octylphenol with mollusc ER and ERR protein was also supported by in vitro studies in transfected HEK-293 cells. Additional in vitro studies with a selection of other potential ligands (including methyl-testosterone, 17α-ethinylestradiol, 4-hydroxytamoxifen, diethylstilbestrol, cyproterone acetate and ICI182780) showed no interaction when tested using this assay. In repeated in vitro tests, however, genistein (with mcER-like) and bisphenol-A (with mcERR) increased reporter gene expression at high concentrations only (>10−6 M for Gen and >10−5 M for BPA, respectively). Like vertebrate estrogen receptors, the mollusc ER protein bound to the consensus vertebrate estrogen-response element (ERE). Together, these data provide no substantial evidence that mcER-like and mcERR activation and transcript levels in tissues are modulated by the vertebrate estrogen estradiol-17β or 4-tert-Octylphenol in vivo, or that other ligands of vertebrate ERs and ERRs (with the possible exception of genistein and bisphenol A, respectively) would do otherwise.BBSR
Toward Higher Sensitivity in Quantitative MALDI Imaging Mass Spectrometry of CNS Drugs Using a Nonpolar Matrix
Tissue-specific ion suppression is an unavoidable matrix effect in MALDI mass spectrometry imaging (MALDI-MSI), the negative impact of which on precision and accuracy in quantitative MALDI-MSI can be reduced to some extent by applying isotope internal standards for normalization and matrix-matched calibration routines. The detection sensitivity still suffers, however, often resulting in significant loss of signal for the investigated analytes. An MSI application considerably affected by this phenomenon is the quantitative spatial analysis of central nervous system (CNS) drugs. Most of these drugs are low molecular weight, lipophilic compounds, which exhibit inefficient desorption and ionization during MALDI using conventional polar acidic matrices (CHCA, DHB). Here, we present the application of the (2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile) matrix for high sensitivity imaging of CNS drugs in mouse brain sections. Since DCTB is usually described as an electron-transfer matrix, we provide a rationale (i.e., computational calculations of gas-phase proton affinity and ionization energy) for an additional proton-transfer ionization mechanism with this matrix. Furthermore, we compare the extent of signal suppression for five different CNS drugs when employing DCTB versus CHCA matrices. The results showed that the signal suppression was not only several times lower with DCTB than with CHCA but also depended on the specific tissue investigated. Finally, we present the application of DCTB and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry to quantitative MALDI imaging of the anesthetic drug xylazine in mouse brain sections based on a linear matrix-matched calibration curve. DCTB afforded up to 100-fold signal intensity improvement over CHCA when comparing representative single MSI pixels and >440-fold improvement for the averaged mass spectrum of the adjacent tissue sections
Электропривод и электрооборудование механизма подъема экскаватора ЭШ 20/90
Произведен расчёт и выбор силового оборудования для электропривода механизма подъема одноковшового экскаватора ЭШ 20/90.
Исследованы статические и динамические характеристики двухконтурной системы автоматического регулирования электропривода экскаватора.The calculation and choice of power equipment for the electric drive of the lifting mechanism of the one-bucket excavator ES 20/90 is made.
The static and dynamic characteristics of a two-circuit automatic control system for the electric drive of an excavator are studied
Disease profile and health-related quality of life (HRQoL) using the EuroQol (EQ-5D + C) questionnaire for chronic metallic mercury vapor intoxication
Steckling N, Plaß D, Bose-O’Reilly S, Kobal AB, Krämer A, Hornberg C. Disease profile and health-related quality of life (HRQoL) using the EuroQol (EQ-5D + C) questionnaire for chronic metallic mercury vapor intoxication. Health and Quality of Life Outcomes. 2015;13(1): 196.Background
Toxic mercury is still being used today for example by workers mining gold, resulting in diverse health symptoms in users and individuals in proximity. A considerable burden of disease (BoD) can be assumed, while previous analyses were limited by data scarcity. Besides limited epidemiological data, neither data about the health-related quality of life (HRQoL) nor about the disease severity (disability weight, DW) is available. The aim of the project was to develop disease profiles of chronic metallic mercury vapor intoxication (CMMVI) by including the HRQoL to improve the data basis for BoD analyses of gold miners exposed to mercury.
Methods
Disease profiles comprising the disease label [a], differentiation into disease stages [b], description of the cause of exposure [c], a list of common symptoms [d], and an assessment of the HRQoL [e] were developed using expert elicitation and literature search. The HRQoL was assessed by experts using the five EuroQol dimensions accompanied by the cognition add-on questionnaire (EQ-5D + C).
Results
The ten sources used for the analyses (interview transcript, presentation, and eight literature reviews) identified more than 250 terms describing 85 distinguishable health effects of CMMVI. The analysis revealed 29 common symptoms that were frequently mentioned. Moderate and severe CMMVI cases differ regarding their symptoms and/or symptom severity and HRQoL, resulting in the EQ-5D + C-3L codes 121222 and 233333, respectively.
Conclusions
The profiles should be used to facilitate the ascertainment of CMMVI cases, to compare the HRQoL with other diseases, to derive DWs for improving BoD estimates, and to foster discussions about how to reduce the associated burden
- …