bluuebunny/crossref_metadata_2025 huggingface dataset:
Alpl prevents bone ageing sensitivity by specifically regulating senescence and differentiation in mesenchymal stem cells
Authors: Liu Wenjia , Zhang Liqiang , Xuan Kun , Hu Chenghu , Liu Shiyu , Liao Li , Li Bei , Jin Fang , Shi Songtao , Jin Yan
Published: September 2018

Mutations in the liver/bone/kidney alkaline phosphatase (Alpl) gene cause hypophosphatasia (HPP) and early-onset bone dysplasia, suggesting that this gene is a key factor in human bone development. However, how and whereAlplacts in bone ageing is largely unknown. Here, we determined that ablation ofAlplinduces prototypical premature bone ageing characteristics, including bone mass loss and marrow fat gain coupled with elevated expression of p16INK4A(p16) and p53 due to senescence and impaired differentiation in mesenchymal stem cells (MSCs). Mechanistically,Alpldeficiency in MSCs enhances ATP release and reduces ATP hydrolysis. Then, the excessive extracellular ATP is, in turn, internalized by MSCs and causes an elevation in the intracellular ATP level, which consequently inactivates the AMPKα pathway and contributes to the cell fate switch of MSCs. Reactivating AMPKα by metformin treatment successfully prevents premature bone ageing inAlpl+/-mice by improving the function of endogenous MSCs. These results identify a previously unknown role ofAlplin the regulation of ATP-mediated AMPKα alterations that maintain MSC stemness and prevent bone ageing and show that metformin offers a potential therapeutic option.
Disruption of Tmem30a results in cerebellar ataxia and degeneration of Purkinje cells
Authors: Yang Yeming , Sun Kuanxiang , Liu Wenjing , Zhang Lin , Peng Kun , Zhang Shanshan , Li Shujin , Yang Mu , Jiang Zhilin , Lu Fang , Zhu Xianjun
Published: September 2018

Phospholipids are asymmetrically distributed across mammalian plasma membrane with phosphatidylserine (PS) and phosphatidylethanolamine concentrated in the cytoplasmic leaflet of the membrane bilayer. This asymmetric distribution is dependent on a group of P4-ATPases named PS flippases. The proper transport and function of PS flippases require a β-subunit transmembrane protein 30 A (TMEM30A). Disruption of PS flippases led to several human diseases. However, the roles of TMEM30A in the central nervous system remain elusive. To investigate the role of Tmem30a in the cerebellum, we developed a Tmem30a Purkinje cell (PC)-specific knockout (KO) mouse model. The Tmem30a KO mice displayed early-onset ataxia and progressive PC death. Deficiency in Tmem30a led to an increased expression of Glial fibrillary acidic protein and astrogliosis in regions with PC loss. Elevated C/EBP homologous protein and BiP expression levels indicated the presence of endoplasmic reticulum stress in the PCs prior to visible cell loss. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis suggested that apoptotic cell death occurred in the cerebellum. Our data demonstrate that loss of Tmem30a in PCs results in protein folding and transport defects, a substantial decrease in dendritic spine density, increased astrogliosis and PC death. Taken together, our data demonstrate an essential role of Tmem30a in the cerebellum PCs.
Publisher Correction: Collective molecular switching in hybrid superlattices for light-modulated two-dimensional electronics
Authors: Gobbi Marco , Bonacchi Sara , Lian Jian X. , Vercouter Alexandre , Bertolazzi Simone , Zyska Björn , Timpel Melanie , Tatti Roberta , Olivier Yoann , Hecht Stefan , Nardi Marco V. , Beljonne David , Orgiu Emanuele , Samorì Paolo
Published: September 2018

The original version of this article incorrectly listed an affiliation of Sara Bonacchi as ‘Present address: Institut National de la Recherche Scientifique (INRS), EMT Center, Boulevard Lionel-Boulet, Varennes, QC, J3X 1S2, 1650, Canada’, instead of the correct ‘Present address: Department of Chemical Sciences - University of Padua - Via Francesco Marzolo 1 - 35131 Padova - Italy’. And an affiliation of Emanuele Orgiu was incorrectly listed as ‘Present address: Department of Chemical Sciences, University of Padua, Via Francesco Marzolo 1, Padova, 35131, Italy’, instead of the correct ‘Present address: Institut National de la Recherche Scientifique (INRS), EMT Center, Boulevard Lionel-Boulet, Varennes, QC, J3X 1S2, 1650, Canada’. This has been corrected in both the PDF and HTML versions of the article.
GraphDDP: a graph-embedding approach to detect differentiation pathways in single-cell-data using prior class knowledge
Authors: Costa Fabrizio , Grün Dominic , Backofen Rolf
Published: September 2018

Cell types can be characterized by expression profiles derived from single-cell RNA-seq. Subpopulations are identified via clustering, yielding intuitive outcomes that can be validated by marker genes. Clustering, however, implies a discretization that cannot capture the continuous nature of differentiation processes. One could give up the detection of subpopulations and directly estimate the differentiation process from cell profiles. A combination of both types of information, however, is preferable. Crucially, clusters can serve as anchor points of differentiation trajectories. Here we present GraphDDP, which integrates both viewpoints in an intuitive visualization. GraphDDP starts from a user-defined cluster assignment and then uses a force-based graph layout approach on two types of carefully constructed edges: one emphasizing cluster membership, the other, based on density gradients, emphasizing differentiation trajectories. We show on intestinal epithelial cells and myeloid progenitor data that GraphDDP allows the identification of differentiation pathways that cannot be easily detected by other approaches.
Large intrinsic anomalous Hall effect in half-metallic ferromagnet Co3Sn2S2 with magnetic Weyl fermions
Authors: Wang Qi , Xu Yuanfeng , Lou Rui , Liu Zhonghao , Li Man , Huang Yaobo , Shen Dawei , Weng Hongming , Wang Shancai , Lei Hechang
Published: September 2018

The origin of anomalous Hall effect (AHE) in magnetic materials is one of the most intriguing aspects in condensed matter physics and has been a controversial topic for a long time. Recent studies indicate that the intrinsic AHE is closely related to the Berry curvature of occupied electronic states. In a magnetic Weyl semimetal with broken time-reversal symmetry, there are significant contributions to Berry curvature around Weyl nodes, possibly leading to a large intrinsic AHE. Here, we report the quite large AHE in the half-metallic ferromagnet Co3Sn2S2 single crystal. By systematically mapping out the electronic structure of Co3Sn2S2 both theoretically and experimentally, we demonstrate that the intrinsic AHE from the Weyl fermions near the Fermi energy is dominating. The intrinsic anomalous Hall conductivity depends linearly on the magnetization and can be reproduced by theoretical simulation, in which the Weyl nodes monotonically move with the constrained magnetic moment on Co atom.
Size-dependent loss of aboveground animals differentially affects grassland ecosystem coupling and functions
Authors: Risch A. C. , Ochoa-Hueso R. , van der Putten W. H. , Bump J. K. , Busse M. D. , Frey B. , Gwiazdowicz D. J. , Page-Dumroese D. S. , Vandegehuchte M. L. , Zimmermann S. , Schütz M.
Published: September 2018

Increasing evidence suggests that community-level responses to human-induced biodiversity loss start with a decrease of interactions among communities and between them and their abiotic environment. The structural and functional consequences of such interaction losses are poorly understood and have rarely been tested in real-world systems. Here, we analysed how 5 years of progressive, size-selective exclusion of large, medium, and small vertebrates and invertebrates—a realistic scenario of human-induced defaunation—impacts the strength of relationships between above- and belowground communities and their abiotic environment (hereafter ecosystem coupling) and how this relates to ecosystem functionality in grasslands. Exclusion of all vertebrates results in the greatest level of ecosystem coupling, while the additional loss of invertebrates leads to poorly coupled ecosystems. Consumer-driven changes in ecosystem functionality are positively related to changes in ecosystem coupling. Our results highlight the importance of invertebrate communities for maintaining ecological coupling and functioning in an increasingly defaunated world.
Three-dimensional motion analysis for comprehensive understanding of gait characteristics after sciatic nerve lesion in rodents
Authors: Tajino Junichi , Ito Akira , Tanima Momoko , Yamaguchi Shoki , Iijima Hirotaka , Nakahata Akihiro , Kiyan Wataru , Aoyama Tomoki , Kuroki Hiroshi
Published: September 2018

Rodent models of sciatic nerve lesion are regularly used to assess functional deficits in nerves. Impaired locomotor functions induced by sciatic nerve lesion are currently evaluated with scoring systems despite their limitations. To overcome these shortcomings, which includes low sensitivity, little significance, and the representation of only marginal components of motion profiles, some additional metrics have been introduced. However, a quantitative determination of motion deficits is yet to be established. We used a three-dimensional motion analysis to investigate gait deficits after sciatic nerve lesion in rats. This enabled us to depict the distorted gait motion using both traditional parameters and novel readouts that are specific for the three-dimensional analysis. Our results suggest that three-dimensional motion analysis facilitates a comprehensive understanding of the gait impairment specifically, but not limited to, a sciatic lesion rat model. A broad application of these methods will improve understanding and standardized motor assessment.
Nystatin-like Pseudonocardia polyene B1, a novel disaccharide-containing antifungal heptaene antibiotic
Authors: Kim Hye-Jin , Han Chi-Young , Park Ji-Seon , Oh Sang-Hun , Kang Seung-Hoon , Choi Si-Sun , Kim Jung-Min , Kwak Jin-Hwan , Kim Eung-Soo
Published: September 2018

Polyene macrolides such as nystatin A1 and amphotericin B belong to a large family of very valuable antifungal polyketide compounds typically produced by soil actinomycetes. Recently, nystatin-like Pseudonocardia polyene (NPP) A1 has been identified as a unique disaccharide-containing tetraene antifungal macrolide produced by Pseudonocardia autotrophica. Despite its significantly increased water solubility and decreased hemolytic activity, its antifungal activity remains limited compared with that of nystatin A1. In this study, we developed NPP B1, a novel NPP A1 derivative harboring a heptaene core structure, by introducing two amino acid substitutions in the putative NADPH-binding motif of the enoyl reductase domain in module 5 of the NPP A1 polyketide synthase NppC. The low level NPP B1 production yield was successfully improved by eliminating the native plasmid encoding a polyketide biosynthetic gene cluster present in P. autotrophica. In vitro and in vivo antifungal activity and toxicity studies indicated that NPP B1 exhibited comparable antifungal activity against Candida albicans and was less toxic than the most potent heptaene antifungal, amphotericin B. Moreover, NPP B1 showed improved pharmacokinetic parameters compared to those of amphotericin B, suggesting that NPP B1 could be a promising candidate for development into a pharmacokinetically improved and less-toxic polyene antifungal antibiotic.
Author Correction: Evolutionary history of plant hosts and fungal symbionts predicts the strength of mycorrhizal mutualism
Authors: Hoeksema Jason D. , Bever James D. , Chakraborty Sounak , Chaudhary V. Bala , Gardes Monique , Gehring Catherine A. , Hart Miranda M. , Housworth Elizabeth Ann , Kaonongbua Wittaya , Klironomos John N. , Lajeunesse Marc J. , Meadow James , Milligan Brook G. , Piculell Bridget J. , Pringle Anne , Rúa Megan A. , Umbanhowar James , Viechtbauer Wolfgang , Wang Yen-Wen , Wilson Gail W. T. , Zee Peter C.
Published: September 2018

In the original published version of the article, the description of the fixed-effect predictor Inoculum Complexity presented in the Methods was incorrect. The incorrect description given was: “single fungal genus, multiple fungal genera, or whole soil inoculum”. The correct description is: “single fungal species, multiple fungal species, or whole soil inoculum”. The error does not affect any of the results presented in the paper. The correction has been made to the HTML and PDF versions of the paper.
Application of ultrasonication for facilitating the extraction of hippuric acid and methyl hippuric acid in real samples using Fe3O4@SiO2@sodium dodecyl sulfate: experimental design methodology
Authors: Omidi Fariborz , Behbahani Mohammad , Khadem Monireh , Golbabaei Farideh , Shahtaheri Seyed Jamaleddin
Published: September 2018

A surfactant assisted dispersive micro solid phase extraction method coupled with ultrasonic power is reported for determination of HA and MHA from human urine samples.
Selective aerobic oxidation of halides and amines with an inorganic-ligand supported zinc catalyst
Authors: Wang Jingjing , Zhai Yongyan , Wang Ying , Yu Han , Zhao Wenshu , Wei Yongge
Published: September 2018

A practical, efficient and environmentally benign catalytic protocol for the oxidative cross-coupling reaction of halides with amines, oxidative self-coupling of amines and oxidation of halides was developed with inorganic-ligand supported ZnPOM (NH4)4[ZnMo6O18(OH)6] using molecular oxygen.
Aspalathus linearis (Rooibos) – a functional food targeting cardiovascular disease
Authors: Smith Carine , Swart Amanda
Published: September 2018

Aspalathus linearis(Rooibos) is a promising candidate which may impact cardiovascular disease (CVD). This review integrates relevant literature on the therapeutic potential of Rooibos in this context.
Heterostructure of two different 2D materials based on MoS2nanoflowers@rGO: an electrode material for sodium-ion capacitors
Authors: Ramakrishnan Kiruthiga , Nithya Chandrasekaran , Karvembu Ramasamy
Published: September 2018

A MoS2nanoflower@rGO composite has been prepared using a simple and scalable hydrothermal method followed by an ultra sonication process.
Glycodendron–rhenium complexes as luminescent probes for lectin sensing
Authors: Palmioli Alessandro , Panigati Monica , Bernardi Anna
Published: September 2018

Enhanced emission intensity of novel Re(i)-glycoprobes resulting from the specific recognition of carbohydrate-binding proteins as a potential tool in bioimaging applications.
Surprising solvent-induced structural rearrangements in large [N⋯I+⋯N] halogen-bonded supramolecular capsules: an ion mobility-mass spectrometry study
Authors: Warzok Ulrike , Marianski Mateusz , Hoffmann Waldemar , Turunen Lotta , Rissanen Kari , Pagel Kevin , Schalley Christoph A.
Published: September 2018

Ion-mobility mass spectrometry and DFT calculations reveal the surprisingly solvent-dependent formation of large pentameric [N⋯I+⋯N] halogen-bonded capsules.
Rational synthesis of benzimidazole[3]arenes by CuII-catalyzed post-macrocyclization transformation
Authors: Tashiro Shohei , Umeki Tsutomu , Kubota Ryou , Shionoya Mitsuhiko
Published: September 2018

A new series of calix[n]arene analogues, benzimidazole[3]arenes, was rationally synthesized by CuII-catalyzed post-macrocyclization transformation of a tris(o-phenylenediamine) macrocycle, and fully characterized by NMR, MS, and single-crystal X-ray diffraction (XRD) analyses.
HEVC transforms with reduced elements bit depth
Authors: Harize S. , Mefoued A. , Kouadria N. , Doghmane N.
Published: September 2018

High‐efficiency video coding (HEVC) is based on integer discrete cosine transforms (DCTs) of size 4 × 4, 8 × 8, 16 × 16 and 32 × 32 whose elements are coded on 8 bits. However, the algorithm requires that the output length at each processing stage should never exceed 16 bits. The conventional solution is the truncation of the least significant bits which leads to erroneous results and a waste of resources. In this Letter, different DCT kernels with reduced elements length are proposed. They are evaluated for compression efficiency and hardware implementation competence. An implementation on the Xilinx FPGA virtex‐6 circuit has given a maximal operating frequency increase of 4.81 and 93.41% for the DCT‐II 4 × 4 and the discrete sine transform, while reducing the energy consumption by 10.64 and 30.77% at 100 MHz, respectively. Using the HM 16.3 HEVC model and video sequences of different resolutions, the results show a quality degradation of 0.01 dB for a bit rate increase of 0.19% compared to the reference cores.
Self‐capacitance grading approach to suppress winding resonance in EHV transformers under oscillatory terminal disturbances
Authors: De Shampa , De Abhinandan , Bandyopadhyay Gautam
Published: September 2018

Interleaving of the high‐voltage winding turns is a widely‐accepted method for restraining the surge voltage stresses in extra high voltage (EHV) transformers. Reduction of voltage stresses under external surge is attributed by the increase in the self‐capacitance of the interleaved winding disks. However, the apparent benefit of interleaving may be counterpoised by a significant decrease of natural frequency of windings, which in turn, may force a winding to resonate under external surges. Winding resonance is particularly noticeable when uniform interleaving is adopted for the whole winding, uniform interleaving attributes a unique natural frequency to all interleaved coils and consequently, the collective resonance of the winding disks is plausible. Uniform interleaving in large EHV transformers therefore leads to complications and the windings reportedly exhibit an unexpectedly poor surge voltage response because of such internal resonances. This study describes a novel concept termed as ‘graded interleaving’ for EHV transformer windings to overcome resonance and to achieve an improved response against surge voltage. The performance of the proposed winding was tested on a 132/33 kV two‐winding transformer with a tap changer using EMTP(ATP) simulations with encouraging results. Manufacturing and real‐time implementation feasibility of the winding were verified with transformer manufacturers.
Gramian‐based model‐order reduction of constrained structural dynamic systems
Authors: Monir Uddin M.
Published: September 2018

This study discusses model reduction techniques for second‐order index 3 descriptor systems using the balanced truncation methods; in particular, linearised equations of motion with holonomic constraints are considered which arise in mechanics and multibody dynamics. It is shown that the index 3 system can be converted into an equivalent form of index 0 system by projecting it onto the hidden manifold. When model reduction is applied to the projected system, explicit formulation of the projected system is not required. The low‐rank alternating direction implicit iteration is also discussed for solving the projected Lyapunov equations of the underlying descriptor system efficiently in an implicit way. The theoretical results are illustrated by numerical experiments.
Optimised phase shift control to minimise current stress of three‐level dual active bridge DC–DC converter
Authors: Jin Li , Duan Shanxu
Published: September 2018

The current stress of three‐level dual active bridge (3L‐DAB) converter under the conventional phase shift (CPS) control becomes much high, especially when the voltage conversion ratio is unequal to one, which may bring low efficiency and damage of power devices. An optimised phase shift (OPS) control strategy is presented to address the issue. The OPS control is realised by calculating the optimal operation point with real‐time detection of voltages and current. The principle of 3L‐DAB under CPS control is presented. The mathematical models of transmission power and current stress are then established. The minimum current stress and the corresponding optimal phase shift ratios are deduced within different ranges of transmission power and voltage conversion ratio, the comparative analysis of current stress and reflux power under OPS and CPS controls have been carried out. The current stress is minimised with any given transmission power and voltage conversion ratio in the whole power range after adopting the OPS control strategy. Moreover, the reflux power is reduced as well within the boundary of voltage conversion range. An experimental prototype was developed to verify the effectiveness of the proposed control strategy and the correctness of the theoretical analysis.
Optimal load frequency control in deloaded tidal power generation plant‐based interconnected hybrid power system
Authors: Kumar Akshay , Shankar Gauri
Published: September 2018

In recent years, power utilities have witnessed increase in penetration of tidal power generation plant (TPGP) into the power system network and, hence, it may collaborate with conventional units in frequency regulation process to ensure power system stability. Therefore, this study presents a method to monitor the participation of TPGP in load frequency control mechanisms in the presence of conventional unit such as diesel power generation plant. The participation of TPGP is showcased based on primary frequency control topologies such as by producing additional inertia, additional damping along with the concept of deloading operation. These approaches are realised by employing conventional controllers to obtain required power (corresponding to different loading conditions) from TPGP by manipulating the kinetic energy of the rotating mass of tidal turbine blades. For better performance and improved stability of the system, the controller parameters are optimised using quasi‐oppositional harmony search algorithm (QOHSA). The effectiveness of QOHSA is proved by comparing the results obtained by it to those yielded by employing other existing state‐of‐the‐art optimisation methods. The prospective analysis is validated in single‐area and two‐area hybrid power system models through MATLAB simulation studies.
Explaining anomalous forces in dielectric EM drives
Authors: Porcelli Elio B. , Filho Victo S.
Published: September 2018

The authors report some encouraging results with basis on their calculations to forecast the magnitude of anomalous thrust forces measured in resonant microwave cavities with dielectrics, for two configurations known as Cannae‐Drive and Tapered Drive, when operating for high values of power. Despite of the weakness of the forces, both devices could provide us with a novel future propulsion technology by means of a thrust without ejecting propellant. In the calculations, they applied their theoretical model based on the dipole‐environment interaction via generalised quantum entanglements (GQE) ensuring the momentum conservation principle. They obtain good agreement with the experimental measurements, although the anomalous forces have weak magnitude. The control and enhancement of the effect can be accomplished by applying GQE hypothesis in order to allow the future viability of a new technology based on quantum electromagnetic propulsion of aircrafts and vehicles.
The radio jets of SS 433 at millimetre wavelengths
Authors: Martí Josep , Bujalance-Fernández Irene , Luque-Escamilla Pedro L. , Sánchez-Ayaso Estrella , Paredes Josep M. , Ribó Marc
Published: September 2018

Context.SS 433 is historically a well-known microquasar in the Galaxy that has been deeply studied during the four decades elapsed since its discovery. However, observations at very high radio frequencies with good angular resolution are still very scarce in the literature. The present paper tries to partially fill this gap using archival data of the source obtained with the Atacama Large Millimeter Array (ALMA).

Aims.We aim to study the SS 433 jet properties at radio frequencies corresponding to millimetre wavelengths where the synchrotron emitting particles are expected to lose their energy much faster than at lower frequencies of centimetre wavelengths.

Methods.We applied the methods of connected radio interferometry adapted to the ALMA spectral domain for data calibration and reduction. Afterwards, the resulting map was corrected for relativistic and geometric effects. While a detailed theoretical modelling was beyond our scope, we assessed the broad evolutive properties of the jet brightness profile in the context of a semi-analytic model.Results.A resolved view of the SS 433 radio core and jets is presented. In addition to spectral index and magnetic field measurements, we are able to estimate the age of the oldest visible ejecta still radiating significantly at millimetre wavelengths. By combining our findings with those of previous authors at lower frequencies, we confirm that the energy loss of the radiating electrons is dominated by adiabatic expansion instead of synchrotron radiative losses. In addition, we find suggestive evidence for the previously proposed period of slowed expansion within the first months of the ejecta flow, needed to simultaneously match the radiative lifetime observed in the centimetre domain. Our results argue for the need for future coordinated millimetre and centimetre interferometric observations with good time sampling throughout the SS 433 precessional cycle to better understand energetic processes in stellar relativistic jets.
Large wood recruitment and mobility in steep mountain streams of contrast European landscapes
Authors: Galia Tomáš , Škarpich Václav , Tichavský Radek
Published: September 2018

We present a comparative study of large wood (LW) mobility in two steep channels (0.06<S<0.20) of contrast European landscapes during major hydro-geomorphic events of similar magnitude. We investigated a headwater perennial stream draining Central European medium-high mountain relief (the Klepáčský, Hrubý Jeseník Mts, Czech Republic; A≤2.5 km2) and an ephemeral Mediterranean steep stream (the Sfakiano Gorge, Crete, Greece; A≤52 km2). Both studied hydro-geomorphic events were partially accompanied by debris-flood or debris-flow character of sediment transport including significant content of LW. The minimal estimations of transported LW volume were 71.3 m3along 1.7 km long reach in the Klepáčský and 49.4 m3along 4 km long reach in the Sfakiano Gorge. Despite completely different characters of hydrologic regimes, riparian zones and valley confinement settings, living trees in the valley floor played crucial role in wood deposition and development of large jams in both environments. The trees living in the valley floor were the main source of LW in the studied Mediterranean channel, whereas long-term LW recruitment from very steep hillslopes or rock cliffs was quite negligible. On the other hand, previous windstorms in the Klepáčsky caused notable delivery of LW from adjacent hillslopes and LW recruitment by bank erosion occurred only at spatially-limited semi-confined parts of the valley.
Hydrodynamic Simulation of an Irregularly Meandering Gravel-Bed River: Comparison of MIKE 21 FM and Delft3D Flow models
Authors: Parsapour-moghaddam Parna , Rennie Colin D. , Slaney Jonathan
Published: September 2018

This study aims at hydrodynamic modelling of Bow River, which passes through the City of Calgary, Canada. Bow River has a mobile gravel bed. Erosion and deposition processes were exacerbated by a catastrophic flood in 2013. Channel banks were eroded at various locations, and large gravel bars formed, which could lead to water level changes and accordingly more flooding. This study investigates the performance of Delft3D-Flow and MIKE 21 FM to simulate the hydrodynamics of the river during the 2013 flood. MIKE 21FM employs unstructured triangular mesh while Delft3D-Flow model uses curvilinear structured grids. Performance of each model was evaluated by the available historical water levels. The results of this study demonstrated that, with approximately the same averaged grid resolution, MIKE 21 FM resulted in more accurate results with a higher computational cost compared to the Delft3DFlow model. It was shown that Delft3D-Flow model may require higher grid cell resolution to result in comparably same depth-averaged velocities throughout the study area. However, considering the balance between the computational cost and the accuracy of the results, both models were capable to adequately replicate the hydrodynamics of the river during the 2013 flood. Results of statistical KS and ANOVA test analysis showed that the model predictions were sensitive to the horizontal eddy viscosity and the Manning roughness. This confirms the necessity of an appropriate calibration of the generated numerical models. The findings of this study shed light on the Bow River flood modelling, which can guide flood management.
Morphological development of river widenings with variable sediment supply
Authors: Rachelly Cristina , Weitbrecht Volker , Vetsch David F. , Boes Robert M.
Published: September 2018

River widening is a common restoration approach to mitigate the adverse effects of past stream alterations on infrastructure and the riparian ecosystem by stabilizing the river bed and enhancing habitat heterogeneity. In this study, two river widening approaches, excavated and dynamic, are described for the case of moderately steep gravel-bed rivers in the Alpine foothills, with a focus on dynamic river widening. As most channelized rivers exhibit ongoing degradation due to the lack of sediment supply and efforts to restore sediment transport are increasing, the consideration of the response of river widenings to variable sediment supply is important. For this purpose, insights from regime theory are applied to river widening and several experimental flume and field studies on channel response to variable sediment supply are reviewed. Dynamic river widenings are expected to be morphologically active in weakly degraded rivers with sufficient sediment supply, while they may not be an appropriate restoration approach for highly degraded rivers due to persistent impairment of morphological activity.
Studies on Driftwood Motions around Obstacles by Laboratory and Nnumerical Experiments
Authors: Kimura Ichiro , Kitazono Kazuya
Published: September 2018

From the engineering point of view, prediction of driftwood motions around hydraulic obstacles in rivers is important. We carried out laboratory experiments to understand the driftwood behaviour around grid like obstacles and found out that there are two different patterns of the capturing process of driftwood: 2D (two-dimension) type and 3D (threedimensional) type. We proposed the governing parameter "Driftwood Richardson Number" for classifying the types of the driftwood capture. A numerical model to simulate driftwood motions based on the coupling of a Euler type three-dimensional flow model and a Lagrange type twodimensional driftwood model (3D-2D model) is proposed to analyse the driftwood behaviour around obstacles. The numerical model could predict well the flowing pattern of driftwood affected by the secondary current of the first kind in a meandering open channel. The numerical results with obstacles showed that the present 3D-2D type model is applicable only if the driftwood Richardson number is larger than 10, in which the driftwood capturing takes place in the 2D type.
Cycloid flows induced by the Large horizontal coherent structures in the vegetated compound channel
Authors: Hong Son Truong , Uijttewaal WSJ
Published: September 2018

Vegetation in general and mangrove, in particular, plays a significant role in the protection of the coastal and estuarine regions from erosion. In particular, estuarine mangrove forests can effciently reduce the impact of a strong along-bank flow during high tides and high river discharge, creating shelter regions for the development of the ecological system. As estuarine mangrove is usually inundated during high tides and exposed to strong tidal flows, the hydrodynamic of estuarine mangrove forest is similar to that of a vegetated compound channel. In order to gain more insight into this field of the research, a hydraulic laboratory experiment of a shallow flow field in a vegetated compound channel has been conducted. Experimental results confirm a pronounced existence of large horizontal coherent structures (LHCSs). Although the presence of the large horizontal coherent structures in the vegetated channel has been well recognized, it is still unclear how they affect the flow field, mass and momentum exchange in the vegetated compound channel. Detailed analyses of the experimental data reveal more about the role of the large horizontal coherent structures. The flow field under the effect of the large coherent structures shows a spatially and temporally cycloid motion, contributing a large part to the momentum and mass transfer. The quadrant analysis of the Reynolds shear stresses has been applied to examine the connection between the motion of the large horizontal coherent structures and their associated cycloid flow events.
Sediment management in tidal river: A case study of East Beel Khuksia, Bangladesh
Authors: Talchabhadel Rocky , Nakagawa Hajime , Kawaike Kenji
Published: September 2018

The widespread construction of coastal embankments limited the natural deposition on the floodplain and accelerated the silt deposition in river channels. It resulted in drainage congestion and large-scale waterlogging problem. The temporary de-poldering is one of the effective methods to solve this issue. During high tide, muddy water enters the selected tidal basin depositing a major portion of sediment and at low tide, relatively clearer water erodes the riverbed. This paper presents a twodimensional numerical model to simulate the mechanism of sediment transport and deposition during the process of controlled flooding. The model was applied to three different scenarios of the embankment cuts in East beel Khuksia, Bangladesh. The study recommends operating single embankment cut at a time if the tidal equilibrium is fulfilled by the opening size of that embankment cut. The developed model can be used to assess the land heightening in sediment-starved tidal basins and ultimately plan the rotation of tidal basins for sustainable sediment management.
Flow structures in a shallow channel with lateral bed-roughness variation
Authors: Akutina Yulia , Moulin Frédéric , Rouzes Maxime , Eiff Olivier
Published: September 2018

Highly heterogeneous floodplains can give rise to secondary flow structures responsible for the bulk of lateral momentum exchange. Quantifying the redistribution of momentum is required to predict lateral profiles of flow velocity and the associated water level in a river. In the work herein, we focus on studying secondary flow structures and the momentum redistribution associated with a lateral bed-roughness variation in a channel with low relative submergence of the roughness elements, h=k = 3, 2 and 1.5, where h is the flow depth and k is the roughness height. A series of laboratory experiments were performed in a flume containing rows of cubes. They were arranged in two types of regular patterns, with higher and lower frontal density, and placed side by side such that the bed roughness varies in the lateral direction. The measurements were performed using stereoscopic PIV in a vertical cross plane spanning between the two roughness types. The time-averaged and turbulence statistics of the three components of the velocity field were analyzed. First, we focus on the intensity of the secondary currents. As the flow becomes shallower (lower relative submergence), the cross-stream velocity normalized by the streamwise velocity increases. A large-scale secondary current at the border between the two roughnesses as observed in [1] (though in their case between smooth and rough regions) appears for h=k = 3. As h=k decreases, this structure reaches to the same size as the secondary flow generated by the roughness elements. Also, the discharge distribution between the two sides of the channel becomes less uniform with decreasing h=k. In this sense, the relative importance of the roughness difference increases with decreasing water depth. Moreover, higher discharge is observed on the side with higher equivalent sand roughness, contrary to what is observed for smooth-to-rough transition [1, 2]. Time series of the streamwise velocity fluctuations are calculated using Taylor’s “frozen turbulence” hypothesis. In this representation, streamwise velocity streaks are apparent for h=k = 3, but they appear to lose coherence for the most shallow case of h=k=1.5.
Dune geometry estimation using apparent bedload velocity as predictor variable
Authors: Gilja Gordon , Kuspilić Neven
Published: September 2018

Dune formation in river systems influences sediment transport, flow characteristics, bank erosion, flood control, navigation and the protection of land and infrastructure. Research on dunes is mainly flume-based, and conclusions from such research are rarely, if at all, verified with field measurements. Dune formation and geometry in terms of height, length and steepness is most commonly correlated with averaged flow parameters as flow depth. Application of relations defined in flume conditions is limited due to stationary flow conditions and extrapolation issues for natural watercourses. It is reasonable to assume that apparent bedload velocity has significant influence on dune field formation due to nature of movement of sand particles across sandy riverbed. This research investigates applicability of apparent bedload velocity as argument in empirical relations for dune geometric characteristics.
Numerical Simulation of lateral dike breaching due to overtopping
Authors: Dewals Benjamin , Rifai Ismail , El-Kadi Abderrazek Kamal , Greco Massimo , Di Cristo Cristiana , Iervolino Michele , Leopardi Angelo , Vacca Andrea
Published: September 2018

Dikes and levees are encountered very often along rivers. They are crucial as defence structures for flow channelization, protecting population and properties from floods as well as against lateral riverbed migration. However, the combination of their aging and increased exposition to extreme hydrological events may cause these structures to breach, and subsequently to fail. Understanding the dynamics of breaching is very important for developing adequate countermeasures, for civil protection initiatives and for land use planning. Recent literature shows many studies concerning, both from experimental and numerical point of views, frontal dike breaching. Based on several evidences, it is well assessed that depth-integrated numerical models can successfully reproduce this kind of phenomenon (e.g. Greco et al., 2012). Recently, Rifai et al. (2017) investigated a different setup in which the embankment is parallel to the main channel flow and thus a lateral breaching occurs. It is worth noting this scheme resembles real-world situation of levees breaching along a river. In present paper, the capability of depth-integrated approaches in reproducing such tests is investigated. Numerical results obtained with different models are compared against experiments from both the qualitative and quantitative point of views. Considerations about the applicability of depth-integrated models in real world situation of lateral breaching of dikes and levees are also drawn.
Evaluating an optimum slit check dam design by using a 2D unsteady numerical model
Authors: Chen Su-Chin , Tfwala Samkele
Published: September 2018

Debris flow could be catastrophic to residents and property located at their downstream. As a result, engineers have designed several structural countermeasures, such as check dams. Regardless of the many investigations on check dams, uncertainty with respect to their design is still persistent. Against this backdrop, the study aims to assess the efficiency and determine an optimal design of slit check dams for mitigating debris flow and sediment-laden flows in steep channels. The study uses an actual slit check dam located at Landao creek, a tributary to the Beng-gai River in the central range of Taiwan. The creek has an average slope of 7 degrees, while its d50 is approximately 100 mm. Steep slopes, extreme precipitation, poor geologic formations, debris flow and landslides characterise the catchment. Concerning the slit check dam design; there were six rectangular concrete piers (width = 1.5 m, length = 4 m, depth = 8 m), linearly spaced at 1 m in a 180° alignment layout, with the middle 2 piers height reduced by 2.5 m. We evaluated the performance of this configuration and further tested two additional configurations by cutting a single pier and three piers at the centre in a 2D model, Nays-2DH. Hydrograph of a selected storm was used for upstream boundary conditions. Surveys using an unmanned aerial vehicle were conducted pre- and post-storm events to validate numerical solutions. Scour and deposition profiles from the different pier configurations formed the basis of our assessment. The numerical computations yielded valuable results and may provide better understanding in the optimal design of slit check dams. Our findings are of paramount importance to engineers and decision makers with regard to debris flow mitigation, especially in a typhoon prone region like Taiwan.
On bedload measurement performances of high-resolution acoustic (ACVP) and conductivity (CCP) profilers
Authors: Fromant Guillaume , Revil-Baudard Thibaut , Mieras Ryan S. , Hurther David , Chauchat Julien , Puleo Jack A.
Published: September 2018

Intense sediment transport experiments were performed in a gravity driven open-channel flow with two sizes of non-spherical acrylic particles of diameter dp=1.0mm and dp=3.0 mm, and a maximum packing volumetric concentration of 0.55 m3/m3. Two flow conditions were adapted to ensure the same sediment transport regime for particle sizes as sheet flows (Shields numbers above unity) with an equi-repartition of the total net sediment transport rate between the suspended load and the bedload (Suspension number around unity). An acoustic scattering-based system, the Acoustic Concentration and Velocity Profiler (ACVP) and electric conductivity probes, the Conductivity Concentration Profiler (CCP) with two different vertical resolutions of 1mm (CCP1mm) and 2 mm (CCP2mm),were used to measure time-resolved and averaged concentration profiles across the bed-load and suspension layers. A detailed comparative analysis of concentration and sheet flow layer thickness measurements obtained with the two systems across both the suspension and the bedload layers is presented. The capabilities and limitations of the two flow measurement technologies are outlined. Average sediment concentration profiles were overestimated by 10% with the ACVP in the dense sheet layer when ⟨φ(z)⟩ ≳ 0.35, and by 100% with the CCP in the more diluted region when ⟨φ(z)⟩ ≲ 0.015 and ⟨φ(z)⟩ ≲ 0.20 for CCP1mmand CCP2mm, respectively. Good agreement is found elsewhere between the three systems in terms of average and time-resolved concentration as well as bed level position and sheet flow layer thickness.
Application of the wavelet transform to sediment grain sizes analysis with an impact plate for bedload monitoring in sediment bypass tunnels
Authors: Koshiba Takahiro , Sumi Tetsuya
Published: September 2018

An impact plate (IP) is a bedload transport monitoring device developed for a part of the sediment bypass tunnels management. In the measurement, the impact produced by bedload is recorded as the number of impulses (Ip) which is widely used in Japan. Ip, however, has several shortcomings attributed to the insufficient raw signal denoising. In this study, the discrete wavelet transform (DWT), an advanced signal processing technique especially for noisy, non-periodical, and transient signals, was introduced to devise an improved Ip count system solving the problems in the original signal denoising process. The presented results revealed that the DWT is useful for water noise reduction, signal overlap reduction, and mitigating Ip saturation at grain sizes Ds = 50 and 100 mm compared to the original Ip counting system.
Implicit 2D surface flow models performance assessment: Shallow Water Equations vs. Zero-Inertia Model
Authors: Fernández-Pato Javier , Morales-Hernández Mario , García-Navarro Pilar
Published: September 2018

Zero-Inertia (ZI) models are used in overland flow simulation due to their mathematical simplicity, compared to more complex formulations such as Shallow Water (SW) models. The main hypothesis in ZI models is that the flow is driven by water surface and friction gradients, neglecting local accelerations. On the other hand, SW models are a complete dynamical formulation that provide more information at the cost of a higher level of complexity. In realistic problems, the usually huge number of cells required to ensure accurate spatial representation implies a large amount of computing effort and time. This is particularly true in 2D models. Hence, there is an interest in developing efficient numerical methods. In general terms, numerical schemes used to solve time dependent problems can be classified in two groups, attending to the time evaluation of the unknowns: explicit and implicit methods. Explicit schemes offer the possibility to update the solution at every cell from the known values but are restricted by numerical stability reasons. This can lead to very slow simulations in case of using fine meshes. Implicit schemes avoid this restriction at the cost of generating a system of as many equations as computational cells multiplied by the number of variables to solve. In this work, an implicit finite volume numerical scheme has been used to solve the 2D equations in both ZI and SW models. The scheme is formulated so that both quadrilateral and triangular meshes can be used. A conservative linearization is done for the flux terms, leading to a non-structured matrix for unstructured meshes thus requiring iterative methods for solving the system. A comparison between 2D SW and 2D ZI is done in terms of performance, efficiency and mesh requirements, in which both models benefit of an implicit temporal discretization in steady and nearly-steady situations.
An Enhanced Depth-integrated Model for Flows over a Negative Step with Hydraulic Jump
Authors: Uchida Tatsuhiko
Published: September 2018

Depth-integrated models play an important role of predicting flows for several practical problems. There are many contributions to develop an enhanced depth-integrated model to have the ability of evaluating vertical flow structures. However, it is still challenging for the depth integrated models to calculate flows over a negative step accompanying a hydraulic jump, because the separation zone behind the step and the pattern of the hydraulic jump depend on the several hydraulic conditions such as Froude number, step height and downstream water depth. In this study, assuming gravel bed rivers in which the bed is covered with relatively large roughness, an enhanced depth integrated model is developed to calculate various hydraulic jump patterns generated downstream from the negative step. The present method is based on General Bottom Velocity Computation method employing Dynamic Wall Law with 4th degree polynomial velocity distribution (GBVC4-DWL). The model with the virtual bed slope behind the negative step and the critical slope of wave breaking is validated through the comparisons with the experimental results on flows over a negative step for submerged jet. weak jump and undular jump conditions. Then the essential terms of equations which compose the present method to calculate the flow downstream of the negative step are investigated.