270 research outputs found

    Magnetic Separation of Impurities from Hydrometallurgy Solutions and Waste Water Using Magnetic Iron Ore Seeding

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    The removal of iron ion from leaching solution is critical for the recovery of value metals, with the method of choice commonly being crystallization (precipitation). This paper summarized the new improvements in iron removal by precipitation methods in recent years and proposed a novel process, magnetic seeding and separation. The new process can promote iron precipitate aggregation and growth on the surface of the magnetic iron ore seeds. A core-shell structure was formed of iron precipitate and magnetic iron ore seeds, which can be magnetized and coalesced in magnetic field, accelerating the solid-liquid separation. The efficient magnetic flocculation and separation offset the poor settleability and filterability of the residues, contributing to the development of the hydrometallurgy process. Moreover, magnetic seeding and separation was also used for the removal of organic and inorganic contaminants from wastewater, significantly improving the purification efficiency. Therefore, iron ore not only played an important role in mining and steel manufacture, but also can be used to solve some problems in crossing fields

    Effect of miller cycle and fuel injection strategy on performance of marine diesel engine

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    Computational fluid dynamics (CFD) is used to investigate the performance of a large two-stroke marine diesel engine. The simulated model is validated with experimental data. The in-cylinder pressure of the simulated model is in agreement with the experimental data. The errors of NOx and CO2 emissions are also within the accepted range. The effect of Miller cycle, injection sequence and pilot injection on combustion and emissions are investigated using this model. The results show that the in-cylinder pressure decreases with deeper Miller cycle level. However, NOx emissions are reduced only slightly to 8.95 g/kWh. This decrease in NOx emissions does not satisfy the requirements of Tier III. We also found that the injection interval angle between two injectors decreases the combustion pressure. However, the indicated specific fuel consumption is 7.3 g/kWh higher than the base value, when the injection interval angle is 8 °CA. Appropriate pilot injection strategy can decrease NOx emissions and indicated specific fuel consumption, such as P10I5. However, NOx emissions are not reduced sufficiently to meet the requirements of Tier III

    Genetic differentiation in Sichuan jay (Perisoreus internigrans) and its sibling species Siberian jay (P. infaustus)

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    The Pleistocene ice age and recent forest fragmentation have both played a significant role in shaping the population genetic variation of boreal coniferous species in the Qinghai-Tibet Plateau (QTP) and Eurasian coniferous forests. The Sichuan jay is one of the least know endemic bird species in QTP coniferous forests in western China while its sibling species, the Siberian Jay, is widespread within the coniferous forests in northern Eurasia. Here we used 11 microsatellite markers to assay genetic diversity across 58 Sichuan jay samples from China and 205 Siberian jay samples from Sweden and Russia. Results showed three distinct genetic clusters from the Sichuan jay sampling. Furthermore, the pair-wise F-ST values indicated high genetic differentiation not only among the two species but also between Swedish and Russian Siberian jay populations. What is more, a pattern of isolation by distance was found among the analyzed populations. Our study suggests that targeted habitat restoration in fragmented forests and more genetic work is urgently needed for conservation of the Sichuan jay

    Prevalence of malocclusion and occlusal traits in the early mixed dentition in Shanghai, China

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    Background Epidemiological data on malocclusion among Chinese children are scant. The aim of this study was to provide detailed information on the prevalence of malocclusion in early mixed dentition children in Shanghai, China. Methods A cross-sectional survey was conducted from September 2016 to April 2017, and 2,810 children aged 7- to 9- years were selected from 10 primary schools by cluster random sampling. Several occlusal parameters, including Angle molar relationship, overjet, overbite, open bite, anterior and posterior crossbite, midline displacement, scissors bite, and teeth crowding and spacing, were clinically registered by five calibrated orthodontic dentists. Results We found that 79.4% children presented one or more occlusal anomalies. Angle Class I, Class II and Class III molar relationship were recorded in 42.3%, 50.9% and 5.9% of the sample, respectively. The proportion of Class III increased from 5.0% at age 7 to 7.8% at age 9. In the sagittal plane, increased overjet >3 mm was observed in 40.8% subjects, while the prevalence of severe overjet (>8 mm), anterior edge-to-edge (zero overjet) and anterior crossbite were 5.2%, 8.1% and 10.5%, respectively. Vertically, deep overbite >2/3 overlap was found in 6.2% of the children and open bite in 4.3%. Boys exhibited a higher rate of overbite than girls. For the transversal occlusal anomalies, 36.1% of the children had a midline displacement, which was followed by posterior crossbite (2.6%) and scissors bite (1.0%). Teeth space discrepancies were also common anomalies and anterior crowding (>2 mm) affecting 28.4% of the children, while anterior spacing (>4 mm) affecting 9.5%. Girls showed a higher prevalence of anterior crowding and a lower frequency of teeth spacing than boys. Conclusions Our study demonstrated that malocclusion is prevalent among children in the early mixed dentition, and more health resources should be warranted to meet the challenge of prevention or early intervention of malocclusion

    Risk factors for the rupture of intracranial aneurysms: a systematic review and meta-analysis

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    PurposeThe study aimed to identify potential risk factors for aneurysm rupture by performing a systematic review and meta-analysis.Materials and methodsWe systematically searched the PubMed, Embase, and Cochrane Library electronic databases for eligible studies from their inception until June 2023.ResultsEighteen studies involving 17,069 patients with unruptured intracranial aneurysm (UIA) and 2,699 aneurysm ruptures were selected for the meta-analysis. Hyperlipidemia [odds ratio (OR): 0.47; 95% confidence interval (CI): 0.39–0.56; p < 0.001] and a family history of subarachnoid hemorrhage (SAH) (OR: 0.81; 95% CI: 0.71–0.91; p = 0.001) were associated with a reduced risk of aneurysm rupture. In contrast, a large-size aneurysm (OR: 4.49; 95% CI: 2.46–8.17; p < 0.001), ACA (OR: 3.34; 95% CI: 1.94–5.76; p < 0.001), MCA (OR: 2.16; 95% CI: 1.73–2.69; p < 0.001), and VABA (OR: 2.20; 95% CI: 1.24–3.91; p = 0.007) were associated with an increased risk of aneurysm rupture. Furthermore, the risk of aneurysm rupture was not affected by age, sex, current smoking, hypertension, diabetes mellitus, a history of SAH, and multiple aneurysms.ConclusionThis study identified the predictors of aneurysm rupture in patients with UIAs, including hyperlipidemia, a family history of SAH, a large-size aneurysm, ACA, MCA, and VABA; patients at high risk for aneurysm rupture should be carefully monitored.Systematic Review RegistrationOur study was registered in the INPLASY platform (INPLASY202360062)

    Distributed Power Allocation for Sink-Centric Clusters in Multiple Sink Wireless Sensor Networks

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    Due to the battery resource constraints, saving energy is a critical issue in wireless sensor networks, particularly in large sensor networks. One possible solution is to deploy multiple sink nodes simultaneously. Another possible solution is to employ an adaptive clustering hierarchy routing scheme. In this paper, we propose a multiple sink cluster wireless sensor networks scheme which combines the two solutions, and propose an efficient transmission power control scheme for a sink-centric cluster routing protocol in multiple sink wireless sensor networks, denoted as MSCWSNs-PC. It is a distributed, scalable, self-organizing, adaptive system, and the sensor nodes do not require knowledge of the global network and their location. All sinks effectively work out a representative view of a monitored region, after which power control is employed to optimize network topology. The simulations demonstrate the advantages of our new protocol

    Understanding recovery is as important as understanding decline: the case of the crested ibis in China

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    The wild population of the crested ibis (Nipponia nippon) has recovered remarkably from seven individuals in 1981 to over 7000 in 2021. However, it is unclear how key factors, from endogenous density dependence to exogenous environmental pressure, have contributed to the species’ recovery. We used species distribution models to quantify the contributions of climatic variables, human impact, land form and land use in order to understand the recovery process in the context of prevailing environmental conditions. We also calculated the nest density over the past 39 years to estimate the influence of density dependence on population dynamics. We found that the interaction between rice paddy areas and water bodies (rivers, lakes and ponds) had the highest contribution to nest site selection, whereas linear terms for either rice paddies or water bodies alone had little effect. During its recovery, sub-populations in two watersheds have been constrained by high density and have experienced logistic growth, while other sub-populations in over seven watersheds are growing exponentially. Our models indicate that exogenous environmental factors are more important than density restriction at this stage. In China’s transformed landscape, the crested ibis needs both rice paddies and water bodies to fulfil its annual life cycle. Habitat protection should thus cover both habitat types to ensure the long-term survival of this still endangered species

    OsbZIP18, a Positive Regulator of Serotonin Biosynthesis, Negatively Controls the UV-B Tolerance in Rice

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    Serotonin (5-hydroxytryptamine) plays an important role in many developmental processes and biotic/abiotic stress responses in plants. Although serotonin biosynthetic pathways in plants have been uncovered, knowledge of the mechanisms of serotonin accumulation is still limited, and no regulators have been identified to date. Here, we identified the basic leucine zipper transcription factor OsbZIP18 as a positive regulator of serotonin biosynthesis in rice. Overexpression of OsbZIP18 strongly induced the levels of serotonin and its early precursors (tryptophan and tryptamine), resulting in stunted growth and dark-brown phenotypes. A function analysis showed that OsbZIP18 activated serotonin biosynthesis genes (including tryptophan decarboxylase 1 (OsTDC1), tryptophan decarboxylase 3 (OsTDC3), and tryptamine 5-hydroxylase (OsT5H)) by directly binding to the ACE-containing or G-box cis-elements in their promoters. Furthermore, we demonstrated that OsbZIP18 is induced by UV-B stress, and experiments using UV-B radiation showed that transgenic plants overexpressing OsbZIP18 exhibited UV-B stress-sensitive phenotypes. Besides, exogenous serotonin significantly exacerbates UV-B stress of OsbZIP18_OE plants, suggesting that the excessive accumulation of serotonin may be responsible for the sensitivity of OsbZIP18_OE plants to UV-B stress. Overall, we identified a positive regulator of serotonin biosynthesis and demonstrated that UV-B-stress induced serotonin accumulation, partly in an OsbZIP18-dependent manner

    An Engineered Arginase FC Protein Inhibits Tumor Growth In Vitro

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    Arginine is a semiessential amino acid required for the growth of melanoma and hepatocellular carcinoma, and the enzymatic removal of arginine by pegylated arginine deiminase (ADI) or arginase is being tested clinically. Here, we report a genetically engineered arginase FC fusion protein exhibiting a prolonged half-life and enhanced efficacy. The use of this enzyme to treat different tumor lines both inhibited cell proliferation and impaired cellular migration in vitro and in vivo. Our data reinforce the hypothesis that nutritional depletion is a key strategy for cancer treatment
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