Managing Insect and Mite Pests of Texas Corn.

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Rare meteorites common in the Ordovician period

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Most meteorites that fall today are H and L type ordinary chondrites, yet the main belt asteroids best positioned to deliver meteorites are LL chondrites 1,2. This suggests that the current meteorite flux is dominated by fragments from recent asteroid breakup events 3,4 and therefore is not representative over longer (100-Myr) timescales. Here we present the first reconstruction of the composition of the background meteorite flux to Earth on such timescales. From limestone that formed about one million years before the breakup of the L-chondrite parent body 466 Myr ago, we have recovered relict minerals from coarse micrometeorites. By elemental and oxygen-isotopic analyses, we show that before 466 Myr ago, achondrites from different asteroidal sources had similar or higher abundances than ordinary chondrites. The primitive achondrites, such as lodranites and acapulcoites, together with related ungrouped achondrites, made up ∼15-34% of the flux compared with only ∼0.45% today. Another group of abundant achondrites may be linked to a 500-km cratering event on (4) Vesta that filled the inner main belt with basaltic fragments a billion years ago 5. Our data show that the meteorite flux has varied over geological time as asteroid disruptions create new fragment populations that then slowly fade away from collisional and dynamical evolution. The current flux favours disruption events that are larger, younger and/or highly efficient at delivering material to Earth

Сенсибилизация к аллергенам клещей домашней пыли у детей

ДЫХАТЕЛЬНАЯ ГИПЕРЧУВСТВИТЕЛЬНОСТЬАЛЛЕРГОЗЫ РЕСПИРАТОРНЫЕГИПЕРСЕНСИБИЛИЗАЦИЯ РЕСПИРАТОРНАЯРЕСПИРАТОРНАЯ АЛЛЕРГИЯАЛЛЕРГЕНЫКЛЕЩИ ПЫЛЕВЫЕ ДОМАШНИЕDERMATOPHAGOIDES PTERONYSSINUSDERMATOPHAGOIDES FARINAEСЕНСИБИЛИЗАЦИЯ БИОЛОГИЧЕСКАЯСЕНСИБИЛИЗАЦИЯ К АЛЛЕРГЕНАМДЕТИОБЗОР ЛИТЕРАТУРЫАллергические заболевания представляют серьезную проблему современной медицины. Сенсибилизация к ингаляционным аллергенам является одним из ключевых факторов формирования респираторных аллергозов. Среди аэроаллергенов важное значение играют аллергенные компоненты домашней пыли – клещи Dermatophagoides pteronyssinus и Dermatophagoides farinae, составляющие до 90% акарофауны жилых помещений. В формировании сенсибилизации к клещам домашней пыли также предполагается роль индивидуальных источников аллергенов. Сенсибилизация к мажорным компонентам аллергена клещей домашней пыли ассоциируется с риском развития бронхиальной астмы, к минорным (Der p 10) – риском развития перекрестных реакций с тропомиозином других беспозвоночных, тропомиозином человека. Аллергены клещей домашней пыли (Der p 2 и Der f 2) могут быть ответственны за симптомы оральной клещевой анафилаксии, а также способствовать развитию сенсибилизации к бактериальным антигенам Staphylococcus aureus и Escherichia coli. В 1 части статьи изложены биология и источники клеща домашней пыли. Представлена классификация аллергенов, пути сенсибилизации и распространенность сенсибилизации к клещу домашней пыли у детей.Allergic diseases are a serious problem in modern medicine. Sensitization to inhalation allergens is one of the key factors in the formation of respiratory allergoses. Among aeroallergens, allergenic components of domestic dust play an important role – mites Dermatophagoides pteronyssinus and Dermatophagoides farinae, that make up to 90% of the acarofauna of residential premises. In the formation of sensitization to domestic dust mites, the role of individual sources of allergens is also considered. Sensitization to the major components of the domestic dust mite allergens is associated with the risk of developing bronchial asthma, to minor ones (Der p 10) – the risk of cross-reactions with tropomyosin of other invertebrates, human tropomyosin. Domestic dust mite allergens (Der p 2 and Der f 2) may be responsible for the symptoms of oral tick-born anaphylaxis as well as for the development of sensitization to bacterial antigens of Staphylococcus aureus and Escherichia coli. Part 1 of this article outlines biology and sources of the domestic dust mite. The classification of allergens, sensitization pathways and the prevalence of sensitization to domestic dust mite in children are presented

Toxicity of metal and metal oxide nanoparticles : the importance of physicochemical properties and cellular uptake [Elektronisk resurs]

The use of nanoparticles holds great promises in many technical as well as medical applications. However, development of new technologies, such as nanotechnology, is connected with uncertainties and risks. The same properties that from a technical point of view are beneficial may in other aspects be unwanted and harmful for both humans and the environment. In order to avoid unnecessary risks and facilitate the use of safe nanotechnology there is a need for adequate toxicological research, as well as risk assessments of nanoparticles and nanotechnologies. This thesis is mainly focusing on the hazards (toxicity) of nanoparticles, and more specifically metal and metal oxide containing nanoparticles. In paper I, the ability of different nanoparticles, as well as multi-walled carbon nanotubes (MWCNT), to induce a cellular response based on their material composition, was investigated. A high variation between the different particles to induce cytotoxicity, DNA damage and oxidative DNA lesions was observed, where CuO nanoparticles were the most potent. In paper II and III, the role of particle-size on cytotoxicity, DNA damage, mitochondrial depolarization and induction of oxidative DNA lesions was studied. Amongst a number of particle types, only Cu and CuO particles displayed clear size- dependent effects where the nanoparticles were more toxic than the micro-sized particles. In paper IV, the impact of different methodological settings, such as sonication and the use of serum in the cell medium when preparing nanoparticle suspensions, was investigated. Observations revealed that sonication of Cu nanoparticles caused decreased cell viability and increased Cu release compared to non-sonicated particles. Furthermore, serum in the cell medium resulted in less particle agglomeration and increased Cu release compared with medium without serum, but no clear difference in toxicity was detected. In paper III, IV and V, the degree of metal release from Cu, CuO and Ag nanoparticles and subsequent impact on particle toxicity, was investigated. Even though a high Cu release was observed within hours after suspending the particles in cell medium, a toxic response was dependent on intracellular particle uptake, via a so-called Trojan horse type mechanism. In comparison to the high toxicity observed for Cu and CuO nanoparticles, no DNA damage or cytotoxicity was observed after exposure to the Ag nanoparticles, which is likely to depend on low Ag release from the particles. In conclusion, a key property of metal and metal oxide nanoparticles is the release of ions facilitating a toxicological response. Via a so-called Trojan horse type mechanism the solid particles can facilitate uptake into cells and subsequently release toxic ionic