10,511 research outputs found

    Flow behaviour of dielectric liquids in an electric field

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    A family of 10 silicone oils with electrical conductivity similar to 10(-13) S m(-1) (a regime hitherto systematically unexplored) and viscosities ranging from 1 to 2000mPas have been Subjected to an electrical field of up to 1.5kV mm(-1) during flow from a needle. The flow behaviour of these liquids is investigated experimentally in the flow rate regime 10(-8)-10(-12) m(3) s(-1) and we analyse the results using the Ohnesorge number. Due to the low electrical conductivity and high electrical relaxation time of the silicone oils, only unsteady transient jets were found. The onset of this type of jetting has been defined using current measurements and, in contrast to conducting liquids, the non-dimensional jet diameter increases with increase in Ohnesorge number. The time elapsed between the start and finish of jetting increases with increasing Ohnesorge number

    Community succession analysis and environmental biological processes of naturally colonized vegetation on abandoned hilly lands and implications for vegetation restoration strategy in Shanxi, China

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    Data were collected simultaneously at different succession stages using a space-for-time substitution, and were analyzed using the quantitative classification method (TWINSPAN) and the ordination technique (DCA). The community succession of natural colonized plants on abandoned hilly lands in Shanxi are below: Assoc. Potentilla chinensis + Setaria viridis ¨ Assoc. Artemisia sacrorum + S. viridis + Oxytropis caoraloa ¨ Assoc. A. sacrorum + Artemisia capillaries ¨ Assoc. A. capillaries + Pedivularis shansiensis + Echinops pseudosetifer ¨ Assoc. Hippophae rhamnoides. A. sacrorum + Cleistogenes squarrosa ¨ Assoc. H. rhamnoides + Ostryopsis davidiana.A. sacrorum ¨ Assoc. O. davidiana.A. sacrorum + Dendranthema chanetii ¨ Assoc. Populus davidiana.Caragana korshinskii.A. sacrorum ¨ Assoc. Larix principis-rupprechtii.H. rhamnoides.A. sacrorum. This established a recovery model of natural vegetation on abandoned hilly lands in Shanxi. The structure, composition and life-forms changed significantly during succession. Four indices of species diversity were used to analyze changes in the heterogeneity, dominance, richness and evenness of species during the succession process. The species richness and heterogeneity of plant communities increased significantly, the dominance decreased obviously and the evenness decreased slightly. The analysis of variance (ANOVA) also proved the significance of these five indices. Pioneer species of S. viridis, A. sacrorum, O. caoraloa, A. capillaries, P. shansiensis, E. pseudosetifer, C. squarrosa, H. rhamnoides, O. davidia, C. korshinskii, P. davidiana and L. principis-rupprechtii, etc. colonize successfully and play important roles on the vegetation restoration of abandoned hilly lands.Keywords: Abandoned hilly lands, vegetation community succession, environmental biological process, soil quality

    Growth process and diameter structure of Pinus tabulaeformis forest for soil and water conservation in the hilly loess region of China

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    Using stem analysis method, the biomass, growing process and diameter structure of 21-year shady and sunny slope Pinus tabulaeformis forest were investigated in hilly loess-gully region. Results showed that there were distinct difference in the indexes, tree height, diameter at breast height (DBH) and timber volume between shady and sunny slope forest. The biomass, growth status and its diameter structure of shady slope forest were greater than those in sunny slope forest. The fast-growing period of tree was from 9 to 13 years. After 13 years, the annual increment of shady slope forest was greater than that of the sunny slope forest (the annual increment of shady slope forest reached 0.26 m•a-1, whileit was about 0.1 m•a-1 in sunny slope forest in the 21st year).The DBH growth increment of 2 forests were reduced greatly after 13 years, but the declining degree of shady slope forest was less than the sunny slope forest. The current annual increment of shady slope forest was greater than the sunny slope forest after 17 years. There was little difference in the increment of 2 timber production before 13 years. But the increment of shady forest was greater than the sunny forest after 13 years (in the 21styear, the annual increment was 0.0023 m3 in shady slope, but in sunny slope it was only 0.0015 m3). The summit of DBH distribution curve was both partial to left, while the skewness (SK was 0.75) of shadyforest was lower than that of the sunny forest (SK was 1.03) and kurtosis (K was 1.05) of shady forest was higher than that of sunny forest (K was 0.94). The results indicated the density structure of sunny slope forest was greater than shady slope forest

    SERS-Enabled Lab-on-a-Chip Systems

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    Surface-enhanced Raman spectroscopy (SERS) has been combined with microfluidic Lab-on-a-Chip (LoC) systems for sensitive optofluidic detection for more than a decade. However, most microfluidic SERS devices still suffer from analyte contamination and signal irreproducibility. In recent years, both the microfluidics and SERS communities have developed their own solutions that are complementary to each other; their combination even has potential for commercialization. In this review, the recent advances in both fields are summarized with regard to the development of reliable multifunctional SERS-enabled LoC systems and their broad applications. Starting from SERS fundamentals, reproducible SERS substrates and dynamic microfluidic trapping are discussed. Based on their combination, on-chip applications beyond SERS are presented, and insight can be gained into the commercialization of portable SERS chips.postprin

    Thrombotic microangiopathies and acute kidney injury induced by artificial termination of pregnancy

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    Thrombotic microangiopathy (TMA) is a rare, but potentially lethal condition requiring rapid recognition, diagnosis and initiation of therapy. Here, we present two cases of women with hemolytic anemia, thrombocytopenia and acute kidney injury shortly after surgical termination of pregnancy. Histological examination of their kidneys revealed endothelial cell swelling and luminal stenosis or fibrin.containing thrombi in the glomeruli and arterioles, which support the diagnosis of TMA. The patients were treated with hemodialysis, plasma infusion and corticosteroids with or without  immunosuppressive agents. Three weeks after treatment, one patient was cured and symptoms of the other patient markedly improved. Reporting of more cases of TMA associated with surgical termination of pregnancy will provide further insights into this rare disease, possibly aiding in identifying risk factors and improving time to clinical diagnosis, treatment and  prognosis.Key words: Acute renal failure, case studies, induced abortion, pregnancy, thrombotic microangiopath

    High-yield cellulase production in solid-state fermentation by Trichoderma reesei SEMCC-3.217 using water hyacinth (Eichhornia crassipes)

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    In this study, the strain Trichoderma reesei SEMCC-3.217 was used for producing cellulase in solid-state fermentation with water hyacinth (Eichhornia crassipes). The results of fractional factorial design showed that, the addition amount of wheat bran, (NH4)2SO4, CaCl2 and Tween 80 had significant effect on the cellulase production. Then, these four factors were selected for further optimization by central composite design for the yield of cellulase. The statistical analysis of the results showed that, the optimum composition were: 5 g of substrate containing 3.9 g water hyacinth, 1% corn steep liquor, 1% soybean meal, 0.2% NH4NO3, 0.2% KH2PO4, 0.08% MgSO4·7H2O, 2.8% (NH4)2SO4, 1.5% urea, 13.9% wheat bran, 0.08% ZnSO4·7H2O, 0.08% FeCl2 0.05% CaCl2, 0.08% NaNO3, 0.08% KCl and 0.27% (v/v) Tween-80. Under these conditions, the cellulase production was 4-fold increased (13.4 FPIU/g dry solid) compared with the initial level (3.4 FPIU/g dry solid) after 7 days of fermentation in a 250 ml Erlenmeyer flask.Key words: Cellulase, solid-state fermentation, optimization, water hyacinth, Trichoderma reesei

    Influence of human body on massive MIMO indoor channels

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    © 2019 IEEE. Massive MIMO can dramatically improve capacity and spectral efficiency. However, it is not very clear whether it can significantly improve the signal blockage problem that exists in single antenna systems. In this paper, we investigate the impact of the human body on indoor massive MIMO channels, using practically measured channel data for a 32x8 massive MIMO system in a complex office environment. We introduce a parameter of Power Imbalance (PI) indices to estimate the wide-sense none-stationarity in multiple domains and another parameter of Channel Popularity Indices (CPI) to predict the popularity of MIMO channel. We find that in most cases, the presence of the human body still has a non- negligible negative impact. It decreases the ergodic capacity by about 8% and increases the path loss exponent by 1. In average, the ergodic capacity for NLOS channels are 15% higher than that for LOS

    Adipose tissue-derived stem cells in oral mucosa tissue engineering: Enhanced migration and proliferation in co-culture with oral keratinocytes in vitro

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    Tissue-engineered oral mucosa holds a great prospect in urethroplasty and adipose tissue-derived stem cells (ADSCs) may play an important role in this field. In this research, canine oral keratinocytes (OKs) and ADSCs were harvested and cultured in vitro. The affinity between the two cell lines was evaluated by analyzing their migration and proliferation patterns in a co-culture environment. The results demonstrate that both canine ADSCs and OKs showed improved migration in the presence of the other cell line as a co-culture when compared to monoculture. Further, conditioned medium using the supernatant of one cell line accelerated the other cell line’s proliferation rate. Hence, it was concluded that the affinity between OKs and ADSCs was fitting; the presence of ADSCs accelerated the migration and proliferation of OKs in vitro. These results indicate that it is practical to use ADSCs and OKs to construct a tissue-engineered oral mucosa, since the presence of the former could activate the latter in vitro, maybe even in vivo. This may help to build tissue-engineered oral mucosa, which may be a new method for urethroplasty.Key words: Urethroplasty, adipose tissue-derived stem cells, oral keratinocytes, tissue engineering

    Recent development of VUV-based processes for air pollutant degradation

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