A fractal-based model for soil water characteristic curve over entire range of water content

Soil water characteristic curve (SWCC) has been an important role in hydraulic engineering, civil engineer and petroleum engineering, etc. Most of SWCC models neglected the film flow in the dry state, so that they cannot accurately describe the SWCC over entire range of water content. In this work, an alternative fractal model is proposed to predict the SWCC over entire range of water content by combining Campbell and Shiozawa model and Tao model. The proposed model can well predict twelve sets of experimental data, and its parameters, including the fractal dimension, the saturated volumetric water content, the matric suction at oven-dry condition, and the air-entry value, accord with theoretical value. The results show that there is a strong linear relationship between volumetric water content and matrix suction in log-log scale for different fractal pore-size distribution of soils. In addition, good agreement is obtained between the experimental data and the model predictions in all of the cases.Cited as: Jin, T., Cai, X., Chen, Y., Jiang, S., Wei, W. A fractal-based model for soil water characteristic curve over entire range of water content. Capillarity, 2019, 2(4): 66-75, doi: 10.26804/capi.2019.04.0

The Sixth Transmembrane Segment Is a Major Gating Component of the TMEM16A Calcium-Activated Chloride Channel.

Calcium-activated chloride channels (CaCCs) formed by TMEM16A or TMEM16B are broadly expressed in the nervous system, smooth muscles, exocrine glands, and other tissues. With two calcium-binding sites and a pore within each monomer, the dimeric CaCC exhibits voltage-dependent calcium sensitivity. Channel activity also depends on the identity of permeant anions. To understand how CaCC regulates neuronal signaling and how CaCC is, in turn, modulated by neuronal activity, we examined the molecular basis of CaCC gating. Here, we report that voltage modulation of TMEM16A-CaCC involves voltage-dependent occupancy of calcium- and anion-binding site(s) within the membrane electric field as well as a voltage-dependent conformational change intrinsic to the channel protein. These gating modalities all critically depend on the sixth transmembrane segment

Study on Flake Graphite Cathode Surface Microstructure in Relativistic Magnetrons

Flake graphite has excellent explosive electron emission performance for its plenty surface micro-bulges and high graphitization degree, but its advantages have rarely been studied in relativistic magnetrons. In this paper, flake graphite cathodes with different fineness were used in coaxial diodes and relativistic magnetrons, and the influence of the surface microstructure of the flake graphite cathode on the relativistic magnetron performance is demonstrated for the first time. The result showed that the graphite microstructure mainly affected the initiation stage of explosive emission. Moreover, the delay time is determined by the degree of graphitization and the surface microstructure of graphite, and the surface microstructure plays a major role. Under the applied voltage of ~330kV-~490kV, The finer flake graphite possessed a shorter emission delay and facilitated the microwave excitation. The excitation time of finer flake graphite is $\sim 3ns$ , and $\sim 5ns$ for lager flake graphite. After several operations of the relativistic magnetron, the edges of flake graphite were blunted, and the surface of the flake graphite appeared droplet-like areas formed by anode atom sputtering. This work reveals the advantages of the finer flake graphite cathode in the fast priming of the relativistic magnetron, thus shedding new light on cathode design of the relativistic magnetron

An Extractive-and-Abstractive Framework for Source Code Summarization

(Source) Code summarization aims to automatically generate summaries/comments for a given code snippet in the form of natural language. Such summaries play a key role in helping developers understand and maintain source code. Existing code summarization techniques can be categorized into extractive methods and abstractive methods. The extractive methods extract a subset of important statements and keywords from the code snippet using retrieval techniques, and generate a summary that preserves factual details in important statements and keywords. However, such a subset may miss identifier or entity naming, and consequently, the naturalness of generated summary is usually poor. The abstractive methods can generate human-written-like summaries leveraging encoder-decoder models from the neural machine translation domain. The generated summaries however often miss important factual details. To generate human-written-like summaries with preserved factual details, we propose a novel extractive-and-abstractive framework. The extractive module in the framework performs a task of extractive code summarization, which takes in the code snippet and predicts important statements containing key factual details. The abstractive module in the framework performs a task of abstractive code summarization, which takes in the entire code snippet and important statements in parallel and generates a succinct and human-written-like natural language summary. We evaluate the effectiveness of our technique, called EACS, by conducting extensive experiments on three datasets involving six programming languages. Experimental results show that EACS significantly outperforms state-of-the-art techniques in terms of all three widely used metrics, including BLEU, METEOR, and ROUGH-L

Sox9 potentiates BMP2-induced chondrogenic differentiation and inhibits BMP2-induced osteogenic differentiation.

Bone morphogenetic protein 2 (BMP2) is one of the key chondrogenic growth factors involved in the cartilage regeneration. However, it also exhibits osteogenic abilities and triggers endochondral ossification. Effective chondrogenesis and inhibition of BMP2-induced osteogenesis and endochondral ossification can be achieved by directing the mesenchymal stem cells (MSCs) towards chondrocyte lineage with chodrogenic factors, such as Sox9. Here we investigated the effects of Sox9 on BMP2-induced chondrogenic and osteogenic differentiation of MSCs. We found exogenous overexpression of Sox9 enhanced the BMP2-induced chondrogenic differentiation of MSCs in vitro. Also, it inhibited early and late osteogenic differentiation of MSCs in vitro. Subcutaneous stem cell implantation demonstrated Sox9 potentiated BMP2-induced cartilage formation and inhibited endochondral ossification. Mouse limb cultures indicated that BMP2 and Sox9 acted synergistically to stimulate chondrocytes proliferation, and Sox9 inhibited BMP2-induced chondrocytes hypertrophy and ossification. This study strongly suggests that Sox9 potentiates BMP2-induced MSCs chondrogenic differentiation and cartilage formation, and inhibits BMP2-induced MSCs osteogenic differentiation and endochondral ossification. Thus, exogenous overexpression of Sox9 in BMP2-induced mesenchymal stem cells differentiation may be a new strategy for cartilage tissue engineering

Identification of Gut Microbiota Affecting Fiber Digestibility in Pigs

Dietary fiber plays an important role in porcine gut health and welfare. Fiber is degraded by microbial fermentation in the intestine, and most gut microbiota related to fiber digestibility in pigs are worth pursuing. The aim of this study was to identify gut microbiota associated with the apparent total tract digestibility (ATTD) of neutral detergent fiber (NDF) and of acid detergent fiber (ADF) in pigs. Large phenotypic variations in the ATTD of NDF and of ADF were separately found among 274 Suhuai pigs. Microbial community structures were significantly different between high and low fiber digestibility groups. Fourteen genera separately dominated the communities found in the high ATTD (H-AD) of NDF and ADF samples and were in very low abundance in the low ATTD (L-AD) of NDF and ADF samples. In conclusion, norank_f__Bacteroidales_S24-7_group (p Ruminococcaceae_UCG-005 (p unclassified_f__Lachnospiraceae (p Treponema_2 (p Ruminococcaceae_NK4A214_group (p Christensenellaceae_R-7_group (p Treponema_2 (p Ruminococcaceae_NK4A214_group (p Ruminococcaceae_UCG-002 (p [Eubacterium]_coprostanoligenes_group (p < 0.05) were the main genera of gut microbiota affecting the ATTD of ADF in pigs. The most important functions of the above different potential biomarkers were: carbohydrate transport and metabolism, general function prediction only, amino acid transport and metabolism, cell wall/membrane/envelope biogenesis, translation, transcription, replication, energy production and conversion, signal transduction mechanisms, and inorganic ion transport and metabolism. The most important metabolic pathways of the above different potential biomarkers were: membrane transport, carbohydrate metabolism, amino acid metabolism, replication and repair, translation, cell motility, energy metabolism, poorly characterized, nucleotide metabolism, metabolism of cofactors and vitamins, and cellular processes and signaling

Sox9 potentiates BMP2-induced glycosaminoglycans synthesis in MSCs in micromass cultures.

<p>(A): Real-time PCR for the expression of chondrogenic differentiation marker gene ACAN were conducted on day 7 and day 14 after infection of AdGFP, AdBMP2, and/or AdSox9, using GAPDH as a house keeping gene. (B–C): Alcian blue staining for sulfated glycosaminoglycans in micromass cultures of C3H10T1/2 cells on day 7 and day 14 after transduction of indicated recombinant adenoviruses, gross observation (B) and microscope examination (C, 40X) are shown. (D): Alcian blue staining quantifying: cells were extracted with 6 M guanidine hydrochloride, Optical density of the extracted dye was measured at 630 nm. The results were expressed as mean±SD of triplicate experiments, *<i>P<0.05</i>, ^#<i>P<0.01</i>.</p

Cryo-EM structures of the TMEM16A calcium-activated chloride channel

Calcium-activated chloride channels (CaCCs) encoded by TMEM16A(1-3) control neuronal signalling, smooth muscle contraction, airway and exocrine gland secretion, and rhythmic movements of the gastrointestinal system(4-7). To understand how CaCCs mediate and control anion permeation to fulfil these physiological functions, knowledge of the mammalian TMEM16A structure and identification of its pore-lining residues are essential. TMEM16A forms a dimer with two pores(8,9). Previous CaCC structural analyses have relied on homology modelling of a homologue (nhTMEM16) from the fungus Nectria haematococca that functions primarily as a lipid scramblase(10-12), as well as subnanometre-resolution electron cryo-microscopy(12). Here we present de novo atomic structures of the transmembrane domains of mouse TMEM16A in nanodiscs and in lauryl maltose neopentyl glycol as determined by single-particle electron cryo-microscopy. These structures reveal the ion permeation pore and represent different functional states. The structure in lauryl maltose neopentyl glycol has one Ca2+ ion resolved within each monomer with a constricted pore; this is likely to correspond to a closed state, because a CaCC with a single Ca2+ occupancy requires membrane depolarization in order to open (C.J.P.etal., manuscript submitted). The structure in nanodiscs has two Ca2+ ions per monomer and its pore is in a closed conformation; this probably reflects channel rundown, which is the gradual loss of channel activity that follows prolonged CaCC activation in 1 mM Ca2+. Our mutagenesis and electrophysiological studies, prompted by analyses of the structures, identified ten residues distributed along the pore that interact with permeant anions and affect anion selectivity, as well as seven porelining residues that cluster near pore constrictions and regulate channel gating. Together, these results clarify the basis of CaCC anion conduction