Investigating Effects of Heterogeneity and Fracture Distribution on Two-Phase Flow in Fractured Reservoir with adaptive time strategy

Modeling of fluid flow in porous media is a pillar in geoscience applications. Previous studies have revealed that heterogeneity and fracture distribution have considerable influence on fluid flow. In this work, a numerical investigation of two-phase flow in heterogeneous fractured reservoir is presented. First, the discrete fracture model is implemented based on a hybrid-dimensional modeling approach, and an equivalent continuum approach is integrated in the model to reduce computational cost. A multilevel adaptive strategy is devised to improve the numerical robustness and efficiency. It allows up to 4-levels adaption, where the adaptive factors can be modified flexibly. Then, numerical tests are conducted to verify the the proposed method and to evaluate its performance. Different adaptive strategies with 3-levels, 4-levels and fixed time schemes are analyzed to evaluate the computational cost and convergence history. These evaluations demonstrate the merits of this method compared to the classical method. Later, the heterogeneity in permeability field, as well as initial saturation, is modeled in a layer model, where the effect of layer angle and permeability on fluid flow is investigated. A porous medium containing multiple length fractures with different distributions is simulated. The fine-scale fractures are upscaled based on the equivalent approach, while the large-scale fractures are retained. The conductivity of the rock matrix is enhanced by the upscaled fine-scale fractures. The difference of hydraulic property between homogeneous and heterogeneous situations is analyzed. It reveals that the heterogeneity may influence fluid flow and production, while these impacts are also related to fracture distribution and permeability.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Delft Institute of Applied Mathematic

Degradation behaviors and in-vivo biocompatibility of a rare earth- and aluminum-free magnesium-based stent

Biodegradable stents can provide scaffolding and anti-restenosis benefits in the short term and then gradually disappear over time to free the vessel, among which the Mg-based biodegradable metal stents have been prosperously developed. In the present study, a Mg-8.5Li (wt.%) alloy (RE- and Al-free) with high ductility (> 40%) was processed into mini-tubes, and further fabricated into finished stent through laser cutting and electropolishing. In-vitro degradation test was performed to evaluate the durability of this stent before and after balloon dilation. The influence of plastic deformation and residual stress (derived from the dilation process) on the degradation was checked with the assistance of finite element analysis. In addition, in-vivo degradation behaviors and biocompatibility of the stent were evaluated by performing implantation in iliac artery of minipigs. The balloon dilation process did not lead to deteriorated degradation, and this stent exhibited a decent degradation rate (0.15 mm/y) in vitro, but divergent result (> 0.6 mm/y) was found in vivo. The stent was almost completely degraded in 3 months, revealing an insufficient scaffolding time. Meanwhile, it did not induce possible thrombus, and it was tolerable by surrounding tissues in pigs. Besides, endothelial coverage in 1 month was achieved even under the severe degradation condition. In the end, the feasibility of this stent for treatment of benign vascular stenosis was generally discussed, and perspectives on future improvement of Mg-Li-based stents were proposed.Accepted Author ManuscriptBiomaterials & Tissue Biomechanic

Unraveling the genome structure of cyanobacterial podovirus A-4L with long direct terminal repeats

The freshwater cyanobacterial virus (cyanophage) A-4L, a podovirus, can infect the model cyanobacterium Anabaena sp. strain PCC 7120 resulting in a high burst size and forming concentric plaques on its lawns. The complete genome sequence of A-4L was determined by the combination of high-throughput sequencing, terminal transferase-mediated polymerase chain reaction and restriction mapping. It contains 41,750 bp with 810 bp direct terminal repeats and 38 potential open reading frames. As compared with other cyanobacterial podoviruses in diverse ecosystems, the A-4L has the longest terminal repeat and shares similar genome organizations with freshwater members. Furthermore, phylogenetic analysis based on concatenated sequences of eight core proteins indicated that freshwater cyanobacterial podoviruses were clustered together and distinct from marine counterparts, suggesting a clear divergence in the cyanobacterial podovirus lineage between freshwater and marine ecosystems. Our findings uncover the unique genome structure of A-4L which contains long direct terminal repeats, and create the first model system to address knowledge gaps in understanding cyanobacterial virus-host interactions at the molecular level. (C) 2015 Elsevier B.V. All rights reserved

Analysis of cipadesin limonoids from Cipadessa cinerascens using electrospray ionization quadrupole time-of-flight tandem mass spectrometry and quantum chemical calculations

RATIONALE: Limonoids, a class of tetranortriterpenoids, exhibit various biological effects, such as insect antifeedant and growth regulating activities, antimicrobial activity, potent cell adhesion inhibitory effects, antimalarial activity, anticancer activities, and antioxidant activity. The potential application brings the need for reliable, fast and low-cost analysis of this class of compounds. METHODS: Six cipadesin limonoids (1-6), including a pairs of isomers, from leaves and barks of Cipadessa cinerascens were investigated by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) in positive-ion mode. Characteristic processes were further studied by theoretical calculations. RESULTS: 1,3-Hydrogen rearrangement might play a significant role in the cleavage of -O-bridge bond in ring B and further produces some characteristic ions. For [M + Na](+) precursor ions, the product ion at m/z 133 might indicate the structure of ring A and the losses of CO2 and AcOH occur readily. Interestingly, the radical product ion at m/z 460 from [M + Na]+ ions seems to be the characteristic ion for compound 1. A deuterium-labeling experiment supported the processes forming the radical ion. For [M + NH4](+) ions, high-abundance product ions resulting from sequential loss of AcOH can be observed. In addition, a pairs of isomers was unambiguously differentiated based on MS or MS/MS spectra. CONCLUSIONS: In summary, sufficient information obtained from fragmentation experiments of [M + Na](+), [M + NH4](+) or [M + H](+) precursor ions is especially valuable for rapid identification of these limonoids or their metabolites in complex mixtures. The high-abundance radical product ion is of scientific interest. Copyright (C) 2012 John Wiley & Sons, Ltd

Gut microbiota-derived indole 3-propionic acid protects against radiation toxicity via retaining acyl-CoA-binding protein

© 2020 The Author(s). Background: We have proved fecal microbiota transplantation (FMT) is an efficacious remedy to mitigate acute radiation syndrome (ARS); however, the mechanisms remain incompletely characterized. Here, we aimed to tease apart the gut microbiota-produced metabolites, underpin the therapeutic effects of FMT to radiation injuries, and elucidate the underlying molecular mechanisms. Results: FMT elevated the level of microbial-derived indole 3-propionic acid (IPA) in fecal pellets from irradiated mice. IPA replenishment via oral route attenuated hematopoietic system and gastrointestinal (GI) tract injuries intertwined with radiation exposure without precipitating tumor growth in male and female mice. Specifically, IPA-treated mice represented a lower system inflammatory level, recuperative hematogenic organs, catabatic myelosuppression, improved GI function, and epithelial integrity following irradiation. 16S rRNA gene sequencing and subsequent analyses showed that irradiated mice harbored a disordered enteric bacterial pattern, which was preserved after IPA administration. Notably, iTRAQ analysis presented that IPA replenishment retained radiation-reprogrammed protein expression profile in the small intestine. Importantly, shRNA interference and hydrodynamic-based gene delivery assays further validated that pregnane X receptor (PXR)/acyl-CoA-binding protein (ACBP) signaling played pivotal roles in IPA-favored radioprotection in vitro and in vivo. Conclusions: These evidences highlight that IPA is a key intestinal microbiota metabolite corroborating the therapeutic effects of FMT to radiation toxicity. Owing to the potential pitfalls of FMT, IPA might be employed as a safe and effective succedaneum to fight against accidental or iatrogenic ionizing ARS in clinical settings. Our findings also provide a novel insight into microbiome-based remedies toward radioactive diseases. [MediaObject not available: see fulltext.

Phosphorus removal by laboratory-scale unvegetated vertical-flow constructed wetland systems using anthracite, steel slag and related blends as substrate

This research aimed to investigate the phosphorus (P) removal of a series of laboratory-scale unvegetated vertical-flow constructed wetland systems using anthracite, steel slag and related blends as substrate in treatment of low concentration domestic sewage. The long-term performance of P removal was firstly studied by using single substrate of anthracite or steel slag, and three systems applying various combined substrates were investigated when the average P loading rate varied between 0.9 and 1.5 g TP/m(2).d. The results demonstrated that both anthracite and steel slag systems were highly effective in removing total P (TP, 77.17 +/- 23.34% and 90.26 +/- 4.48%) and soluble reactive P (SRP, 92.14 +/- 12.56% and 96.20 +/- 2.58%). The system filled with anthracite, vermiculite and steel slag from the top down removed 82.45 +/- 9.52% and 87.83 +/- 8.58% of TP and SRP, respectively. However, other combined substrate systems showed comparative low and fluctuant P removal. The effluent pH was maintained at 7-9, which met environmental requirements of China. Therefore, anthracite provides a long-term high efficiency of P removal and may be a promising substrate from the standpoint of the effluent pH, and the arrangement of combined substrate has a prominent effect on P removal

The management of undesirable cyanobacteria blooms in channel catfish ponds using a constructed wetland: Contribution to the control of off-flavor occurrences

An exploratory study on the management of undesirable cyanobacteria blooms with respect to off-flavor problems using an integrated vertical-flow constructed wetland (CW) was performed at a small commercial-scale channel catfish farm from 2004 to 2007. The results of the three-year experiment indicated that water treatment by the CW could reduce the possibility of dominance by undesirable cyanobacteria species that often cause off-flavor problems. A detailed investigation in 2007, showed that the concentrations of geosmin, MIB (2-methylisoborneol), and beta-cyclocitral in the water of the recirculating pond (4.3 ng L(-1), U.D. (undetected) and 0.2 ng L(-1), respectively) treated by the CW were significantly lower than those in the control pond (152.6 ng L(-1), 63.3 ng L(-1) and 254.8 ng L(-1), respectively). In addition, the relationships among the cyanobacteria species, the off-flavor compounds and ten environmental variables were explored by canonical correspondence analysis (CCA). The results showed that Oscillatoria sp., Oscillatoria kawamurae and Microcystis aeruginosa were the main sources of off-flavor compounds in the catfish ponds. The successful manipulation of undesirable cyanobacteria species potentially resulted in lower concentrations of odorous compounds in the water of the recirculating pond. An investigation of the concentrations of geosmin and MIB in catfish fillets showed that the levels of odorous compounds were below the OTC (odor threshold concentration) values in the recirculating pond but were above the OTC values from July to October in the control pond. Water recycling by the CW could potentially be one of the best management practices to control off-flavor occurrences in aquaculture. (C) 2011 Elsevier Ltd. All rights reserved

A COMBINATION PROCESS OF DMBR-IVCW FOR DOMESTIC SEWAGE TREATMENT

A new hybrid system of DMBR-IVCW, which combines a dynamic membrane bioreactor (DMBR) unit and an integrated vertical-flow constructed wetland (IVCW) unit, was applied to treat domestic sewage. The results showed the total removal efficiencies of DMBR-IVCW system at three different operation conditions were 90.3, 93.3 and 92.6% for COD, 93.0, 89.8 and 85.1% for TN, 85.4, 88.0 and 90.4% for TP, and 93.3, 97.3 and 99.1% for turbidity, respectively. The effluent reaches the Class I of National Discharge Standards for sewage in China (GB8978-1996), and can be directly used for water reclamation and reuse. We found that the DMBR unit had good efficiency on removing COD and turbidity, together with great steady performance to buffer organic loadings and hydraulic shocks, while the IVCW unit acted more like an ecological enhanced treatment for the DMBR unit, removing N, P and other nutrients. This hybrid system coupling the advantages of the both units should provide an effective method for high quality effluent.A new hybrid system of DMBR-IVCW, which combines a dynamic membrane bioreactor (DMBR) unit and an integrated vertical-flow constructed wetland (IVCW) unit, was applied to treat domestic sewage. The results showed the total removal efficiencies of DMBR-IVCW system at three different operation conditions were 90.3, 93.3 and 92.6% for COD, 93.0, 89.8 and 85.1% for TN, 85.4, 88.0 and 90.4% for TP, and 93.3, 97.3 and 99.1% for turbidity, respectively. The effluent reaches the Class I of National Discharge Standards for sewage in China (GB8978-1996), and can be directly used for water reclamation and reuse. We found that the DMBR unit had good efficiency on removing COD and turbidity, together with great steady performance to buffer organic loadings and hydraulic shocks, while the IVCW unit acted more like an ecological enhanced treatment for the DMBR unit, removing N, P and other nutrients. This hybrid system coupling the advantages of the both units should provide an effective method for high quality effluent

Effect of vegetation type on microstructure of soil aggregates on the Loess Plateau, China

Several types of vegetation restoration have been implemented on the Loess Plateau in China to control soil erosion and improve soil quality. Different revegetation types, however, have varying effects on soil structure; effects on the pore network of aggregates are especially not well understood. We used synchrotron-based high-resolution X-ray micro-computed tomography to quantify the microstructure of soil aggregates under four types of revegetation and an active cropland on the plateau. Five aggregates (3-5 mm) collected from the topsoil at each site were scanned at a voxel resolution of 3.25 mu m, and the aggregate pore structure was visualized and quantified with ImageJ. Total porosities, >75 mu m porosities, fractions of elongated pores, 3D mass fractal dimensions, and connectivity were higher and the numbers of pores, grassland > woodland > pastureland. We recommend shrub plantation and natural grassland for the revegetation of degraded land on the Loess Plateau. (C) 2017 Elsevier B.V. All rights reserved