2,687 research outputs found
Grain size limits derived from 3.6 {\mu}m and 4.5 {\mu}m coreshine
Recently discovered scattered light from molecular cloud cores in the
wavelength range 3-5 {\mu}m (called "coreshine") seems to indicate the presence
of grains with sizes above 0.5 {\mu}m. We aim to analyze 3.6 and 4.5 {\mu}m
coreshine from molecular cloud cores to probe the largest grains in the size
distribution. We analyzed dedicated deep Cycle 9 Spitzer IRAC observations in
the 3.6 and 4.5 {\mu}m bands for a sample of 10 low-mass cores. We used a new
modeling approach based on a combination of ratios of the two background- and
foreground-subtracted surface brightnesses and observed limits of the optical
depth. The dust grains were modeled as ice-coated silicate and carbonaceous
spheres. We discuss the impact of local radiation fields with a spectral slope
differing from what is seen in the DIRBE allsky maps. For the cores L260,
ecc806, L1262, L1517A, L1512, and L1544, the model reproduces the data with
maximum grain sizes around 0.9, 0.5, 0.65, 1.5, 0.6, and > 1.5 {\mu}m,
respectively. The maximum coreshine intensities of L1506C, L1439, and L1498 in
the individual bands require smaller maximum grain sizes than derived from the
observed distribution of band ratios. Additional isotropic local radiation
fields with a spectral shape differing from the DIRBE map shape do not remove
this discrepancy. In the case of Rho Oph 9, we were unable to reliably
disentangle the coreshine emission from background variations and the strong
local PAH emission. Considering surface brightness ratios in the 3.6 and 4.5
{\mu}m bands across a molecular cloud core is an effective method of
disentangling the complex interplay of structure and opacities when used in
combination with observed limits of the optical depth.Comment: 23 pages, 18 figures, accepted for publication in A&
Probing the dynamics of quasicrystal growth using synchrotron live imaging
The dynamics of quasicrystal growth remains an unsolved problem in condensed
matter. By means of synchrotron live imaging, facetted growth proceeding by the
tangential motion of ledges at the solid-melt interface is clearly evidenced
all along the solidification of icosahedral AlPdMn quasicrystals. The effect of
interface kinetics is significant so that nucleation and free growth of new
facetted grains occur in the melt when the solidification rate is increased.
The evolution of these grains is explained in details, which reveals the
crucial role of aluminum rejection, both in the poisoning of grain growth and
driving fluid flow
The Comparison of Characteristics in Tin Doped Indium Oxide (ITO) Synthesized via Nonaqueous Sol-Gel and Solvothermal Process
Tin doped indium oxide nanoparticles were synthesized by nonaqueous sol-gel method and solvothermal process from indium acetylacetonate (In(acac)3) and tin bis(acetylacetonate)dichloride (Sn(acac)2Cl2) in oleyamine as the starting materials. The structure and morphology of ITO samples were analyzed by XRD and TEM. The electrical conductivy and specific surface area of both ITO samples were also determined and compared to each other. The ITO prepared via solvothermal method showed better results that prepared by nonaqueous sol-gel method
On some multiplicity and mixed multiplicity formulas (Forum Math. 26(2014), 413-442)
This paper gives the additivity and reduction formulas for mixed
multiplicities of multi-graded modules and mixed multiplicities of
arbitrary ideals, and establishes the recursion formulas for the sum of all the
mixed multiplicities of As an application of these formulas we get the
recursion formulas for the multiplicity of multi-graded Rees modules
Autophagy Inhibitor Chloroquine Downmodulates Hepatic Stellate Cell Activation and Liver Damage in Bile-Duct-Ligated Mice
Hepatic stellate cell (HSC) activation via the autophagy pathway is a critical factor in liver fibrogenesis. This study tests the hypothesis that chloroquine (CQ) treatment can prevent autophagy and HSC activation in vitro and in vivo in bile-duct-ligated (BDL) mice. Sham-operated and BDL mice were treated with either PBS or CQ in two 60 mg/kg doses the day (D) before and after surgery. On day 2 (2D), HSCs were isolated, and their biological activities were evaluated by measuring intracellular lipid content, alpha-sma/collagen, and expression of autophagy lc3, sqstm1/p62 markers. The treatment efficacy on liver function was evaluated with serum albumin, transaminases (AST/ALT), and hepatic histology. Primary HSCs were treated in vitro for 24 h with CQ at 0, 2.5, 5, 10, 30, and 50 mu M. Autophagy and HSC activation were assessed after 2D of treatment. CQ treatment improved serum AST/ALT, albumin, and bile duct proliferation in 2D BDL mice. This is associated with a suppression of HSC activation, shown by higher HSC lipid content and collagen I staining, along with the blockage of HSC autophagy indicated by an increase in p62 level and reduction in lc3 staining. CQ 5 mu M inhibited autophagy in primary HSCs in vitro by increasing p62 and lc3 accumulation, thereby suppressing their in vitro activation. The autophagy inhibitor CQ reduced HSC activation in vitro and in vivo. CQ improved liver function and reduced liver injury in BDL mice
Mapping for engagement: setting up a community based participatory research project to reach underserved communities at risk for Hepatitis C in Ho Chi Minh City, Vietnam
Background: Approximately 1. 07 million people in Vietnam are infected with hepatitis C virus (HCV). To address this epidemic, the South East Asian Research Collaborative in Hepatitis (SEARCH) launched a 600-patient cohort study and two clinical trials, both investigating shortened treatment strategies for chronic HCV infection with direct-acting antiviral drugs. We conducted ethnographic research with a subset of trial participants and found that the majority were aware of HCV infection and its implications and were motivated to seek treatment. However, people who inject drugs (PWID), and other groups at risk for HCV were under-represented, although injecting drug use is associated with high rates of HCV. Material and Methods: We designed a community-based participatory research (CBPR) study to engage in dialogues surrounding HCV and other community-prioritized health issues with underserved groups at risk for HCV in Ho Chi Minh City. The project consists of three phases: situation analysis, CBPR implementation, and dissemination. In this paper, we describe the results of the first phase (i.e., the situation analysis) in which we conducted desk research and organized stakeholder mapping meetings with representatives from local non-government and community-based organizations where we used participatory research methods to identify and analyze key stakeholders working with underserved populations. Results: Twenty six institutions or groups working with the key underserved populations were identified. Insights about the challenges and dynamics of underserved communities were also gathered. Two working groups made up of representatives from the NGO and CBO level were formed. Discussion: Using the information provided by local key stakeholders to shape the project has helped us to build solid relationships, give the groups a sense of ownership from the early stages, and made the project more context specific. These steps are not only important preliminary steps for participatory studies but also for other research that takes place within the communities
DNA metabarcoding unveils multiscale trophic variation in a widespread coastal opportunist
A thorough understanding of ecological networks relies on comprehensive information on trophic relationships among species. Since unpicking the diet of many organisms is unattainable using traditional morphology‐based approaches, the application of high‐throughput sequencing methods represents a rapid and powerful way forward. Here, we assessed the application of DNA metabarcoding with nearly universal primers for the mitochondrial marker cytochrome c oxidase I in defining the trophic ecology of adult brown shrimp, Crangon crangon, in six European estuaries. The exact trophic role of this abundant and widespread coastal benthic species is somewhat controversial, while information on geographical variation remains scant. Results revealed a highly opportunistic behaviour. Shrimp stomach contents contained hundreds of taxa (>1,000 molecular operational taxonomic units), of which 291 were identified as distinct species, belonging to 35 phyla. Only twenty ascertained species had a mean relative abundance of more than 0.5%. Predominant species included other abundant coastal and estuarine taxa, including the shore crab Carcinus maenas and the amphipod Corophium volutator. Jacobs’ selectivity index estimates based on DNA extracted from both shrimp stomachs and sediment samples were used to assess the shrimp's trophic niche indicating a generalist diet, dominated by crustaceans, polychaetes and fish. Spatial variation in diet composition, at regional and local scales, confirmed the highly flexible nature of this trophic opportunist. Furthermore, the detection of a prevalent, possibly endoparasitic fungus (Purpureocillium lilacinum) in the shrimp's stomach demonstrates the wide range of questions that can be addressed using metabarcoding, towards a more robust reconstruction of ecological networks
Microwave-assisted flow synthesis of multicore iron oxide nanoparticles
Coprecipitation is by far the most common synthesis method for iron oxide nanoparticles (IONPs). However, reproducibility and scalability represent a major challenge. Therefore, innovative processes for scalable production of IONPs are highly sought after. Here, we explored the combination of microwave heating with a flow reactor producing IONPs through coprecipitation. The synthesis was initially studied in a well-characterised microwave-heated flow system, enabling the synthesis of multicore IONPs, with control over both the single core size and the multicore hydrodynamic diameter. The effect of residence time and microwave power was investigated, enabling the synthesis of multicore nanostructures with hydrodynamic diameter between ∼35 and 70 nm, with single core size of 3–5 nm. Compared to particles produced under conventional heating, similar single core sizes were observed, though with smaller hydrodynamic diameters. The process comprised of the initial IONP coprecipitation followed by the addition of the stabiliser (citric acid and dextran). The ability of precisely controlling the stabiliser addition time (distinctive of flow reactors), contributed to the synthesis reproducibility. Finally, scale-up by increasing the reactor length and using a different microwave cavity was demonstrated, producing particles of similar structure as those from the small scale system, with a throughput of 3.3 g/h
H_2 Emission From Disks Around Herbig Ae and T Tauri Stars
We present the initial results of a deep ISO-SWS survey
for the low J pure rotational emission lines of H2
toward a number of Herbig Ae and T Tauri stars.
The objects are selected to be as isolated as possible
from molecular clouds, with a spectral energy distribution
characteristic of a circumstellar disk. For most
of them the presence of a disk has been established
directly by millimeter interferometry. The S (1) line is
detected in most sources with a peak flux of 0.3-1 Jy.
The S(0) line is definitely seen in 2 objects: GG Tau
and HD 163296. The observations suggest the presence
of "warm" gas at T_(kin) ≈ 100 K with a mass of a
few % of the total gas+ dust mass, derived assuming
a gas-to-dust ratio of 100:1. The S(1) peak flux does
not show a strong correlation with spectral type of
the central star or continuum flux at 1.3 millimeter.
Possible origins for the warm gas seen in H_2 are discussed,
and comparisons with model calculations are
made
Организация логистических операций при перевозке электронных бытовых отходов в городах
The paper presents the methodological provisions for the organization of logistics operations during the transportation of household electronic waste in large cities. Human activity is accompanied by the formation of waste, the amount of which has recently increased. In modern conditions, households actively use electronic and electrical devices. Therefore, a lot of household electronic and electrical waste is generated, which is hazardous to the environment and must be disposed of in accordance with legal requirements. The efficiency of disposal of household electronic waste depends on the organization of logistics operations for the collection, accumulation and removal of such waste. The main methodological stages of logistical support for the recycling process include the formation of a hierarchy of territorial formations (taxons), standardization of waste generation indicators for taxa of each level in the hierarchy, designing the configuration of a network of collection points for acceptance and temporary storage of waste within the boundaries of the service area, substantiating the rational storage capacity of each point and deadlines for waste storage; planning the transportation of waste from accumulation points to objects of their further processing. When planning the transportation of waste, the actual volume of waste accumulation at each collection point is taken into account, transportation routes are designed for the shortest distances, taking into account the capacity of vehicles. The main feature of the developed method of waste removal is the operational adjustment of routes so that the car drives only to those accumulation points where the actual volume of waste has reached the maximum storage capacity. This approach ensures timely waste collection and lower transportation costs compared to existing methods that organize waste collection at a specified frequency. The developed methodology was tested on the basis of statistical data from Hanoi (Vietnam). The results of numerical experiments show that the application of methods provides a reduction in transport costs for the removal of household electronic waste, and also increases the level of their collection and disposal.В статье представлены методические положения организации логистических операций при перевозке электронных бытовых отходов в крупных городах. Жизнедеятельность человека сопровождается формированием отходов, количество которых в последнее время возрастает. В современных условиях домохозяйства активно используют электронные и электрические устройства. Поэтому образуется много электронных и электрических бытовых отходов, которые представляют опасность для окружающей среды и должны быть утилизированы с соблюдением законодательных требований. Эффективность утилизации электронных бытовых отходов зависит от организации логистических операций по сбору, накоплению и вывозу таких отходов. Основные методические этапы логистической поддержки процесса утилизации включают: формирование иерархии территориальных образований (таксонов), нормирование показателей генерации отходов для таксонов каждого уровня в иерархии, проектирование конфигурации сети сборных пунктов для приемки и временного хранения отходов в границах обслуживаемой территории, обоснование рациональной складской емкости каждого пункта и предельных сроков хранения отходов, планирование перевозки отходов от пунктов накопления до объектов их последующей обработки. При планировании перевозки отходов учитывается фактический объем накопления отходов в каждом пункте сбора, проектируются маршруты перевозок по кратчайшим расстояниям с учетом вместимости транспортных средств. Главная особенность разработанной методики вывоза отходов заключается в оперативной корректировке маршрутов, чтобы автомобиль заезжал только в те пункты накопления, в которых фактический объем отходов достиг предельной емкости складирования. Данный подход обеспечивает своевременный вывоз отходов и снижение затрат на перевозку по сравнению с существующими методами, которые организуют вывоз отходов с установленной периодичностью. Разработанная методика апробирована на основе статистических данных г. Ханой (Вьетнам). Результаты численных экспериментов показывают, что применение методик обеспечивает снижение транспортных затрат на вывоз электронных бытовых отходов, а также повышает уровень их собираемости и утилизации
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