bluuebunny/crossref_metadata_2025 huggingface dataset:
Earthquakes Within Earthquakes: Patterns in Rupture Complexity
Authors: Danré Philippe , Yin Jiuxun , Lipovsky Bradley P. , Denolle Marine A.
Published: June 2019

Earthquake source time functions carry information about the complexity of seismic rupture. We explore databases of earthquake source time functions and find that they are composed of distinct peaks that we call subevents. We observe that earthquake complexity, as represented by the number of subevents, grows with earthquake magnitude. Patterns in rupture complexity arise from a scaling between subevent moment and main event moment. These results can be explained by simple 2‐D dynamic rupture simulations with self‐affine heterogeneity in fault prestress. Applying this to early magnitude estimates, we show that the main event magnitude can be estimated after observing only the first few subevents.
Mixed-lineage leukemia protein 2 suppresses ciliary assembly by the modulation of actin dynamics and vesicle transport
Authors: Yang Yang , Hao Huijie , Wu Xiaofan , Guo Song , Liu Yang , Ran Jie , Li Te , Li Dengwen , Liu Min , Zhou Jun
Published: June 2019

Primary cilia are critically involved in the coordination of diverse signaling pathways and ciliary defects are associated with a variety of human diseases. The past decades have witnessed great progress in the core machinery orchestrating ciliary assembly. However, the upstream epigenetic cues that direct ciliogenesis remain elusive. Herein, we demonstrate that mixed-lineage leukemia protein 2 (MLL2), a histone methyltransferase, plays a negative role in ciliogenesis. RNA-sequencing analysis reveals that the expression of five actin-associated proteins is significantly downregulated in MLL2-depleted cells. Overexpression of these proteins partially rescues ciliary abnormality elicited by MLL2 depletion. Our data also show that actin dynamics is remarkably changed in MLL2-depleted cells, resulting in the impairment of cell adhesion, spreading, and motility. In addition, MLL2 depletion promotes ciliary vesicle trafficking to the basal body in an actin-related manner. Together, these results reveal that MLL2 inhibits ciliogenesis by modulating actin dynamics and vesicle transport, and suggest that alteration of MLL2 may contribute to the pathogenesis of cilium-associated diseases.
Circuit asymmetries underlie functional lateralization in the mouse auditory cortex
Authors: Levy Robert B. , Marquarding Tiemo , Reid Ashlan P. , Pun Christopher M. , Renier Nicolas , Oviedo Hysell V.
Published: June 2019

The left hemisphere’s dominance in processing social communication has been known for over a century, but the mechanisms underlying this lateralized cortical function are poorly understood. Here, we compare the structure, function, and development of each auditory cortex (ACx) in the mouse to look for specializations that may underlie lateralization. Using Fos brain volume imaging, we found greater activation in the left ACx in response to vocalizations, while the right ACx responded more to frequency sweeps. In vivo recordings identified hemispheric differences in spectrotemporal selectivity, reinforcing their functional differences. We then compared the synaptic connectivity within each hemisphere and discovered lateralized circuit-motifs that are hearing experience-dependent. Our results suggest a specialist role for the left ACx, focused on facilitating the detection of specific vocalization features, while the right ACx is a generalist with the ability to integrate spectrotemporal features more broadly.
Organometallic compounds as carriers of extraterrestrial cyanide in primitive meteorites
Authors: Smith Karen E. , House Christopher H. , Arevalo Ricardo D. , Dworkin Jason P. , Callahan Michael P.
Published: June 2019

Extraterrestrial delivery of cyanide may have been crucial for the origin of life on Earth since cyanide is involved in the abiotic synthesis of numerous organic compounds found in extant life; however, little is known about the abundance and species of cyanide present in meteorites. Here, we report cyanide abundance in a set of CM chondrites ranging from 50 ± 1 to 2472 ± 38 nmol·g−1, which relates to the degree of aqueous alteration of the meteorite and indicates that parent body processing influenced cyanide abundance. Analysis of the Lewis Cliff 85311 meteorite shows that its releasable cyanide is primarily in the form of [FeII(CN)5(CO)]3− and [FeII(CN)4(CO)2]2−. Meteoritic delivery of iron cyanocarbonyl complexes to early Earth likely provided an important point source of free cyanide. Iron cyanocarbonyl complexes may have served as precursors to the unusual FeII(CN)(CO) moieties that form the catalytic centers of hydrogenases, which are thought to be among the earliest enzymes.
Disentangling the relative impacts of climate change and human activities on fluvial sediment supply to the coast by the world’s large rivers: Pearl River Basin, China
Authors: Ranasinghe Roshanka , Wu Chuang Shou , Conallin John , Duong Trang Minh , Anthony Edward Jamal
Published: June 2019

The world’s large rivers are under stress and experiencing unprecedented changes in hydrology, ecosystems, and fluvial sediment loads. Many of these rivers terminate at the great deltas of the world (home to 500 million people), which depend on fluvial sediments for their very existence. While fluvial sediment loads of large rivers have already been greatly modified by human activities, climate change is expected to further exacerbate the situation. But how does the effect of climate change on fluvial sediment loads compare with that of human impacts? Here, we address this question by combining historical observations and 21st century projections for one of the world’s largest 25 rivers containing two mega dams; Pearl River, China. Our analysis shows that variations in fluvial sediment supply to the coast from the Pearl river over a ~150 year study period are dominated by human activities. Projected climate change driven 21st century increases in riverflow will only compensate for about 1% of the human induced deficit in sediment load, leading to the coastal zone being starved of about 6000 Mt of sediment over the remainder of this century. A similar dominance of human impacts on fluvial sediment supply is likely at other heavily engineered rivers.
Purification and characterization of a novel, highly potent fibrinolytic enzyme from Bacillus subtilis DC27 screened from Douchi, a traditional Chinese fermented soybean food
Authors: Hu Yuanliang , Yu Dan , Wang Zhaoting , Hou Jianjun , Tyagi Rohit , Liang Yunxiang , Hu Yongmei
Published: June 2019

The highly fibrinolytic enzyme-producing bacterium was identified as Bacillus subtilis DC27 and isolated from Douchi, a traditional fermented soybean food. The DFE27 enzyme was purified from the fermentation broth of B. subtilis DC27 by using UNOsphere Q column chromatography, Sephadex G-75 gel filtration, and high-performance liquid chromatography. It was 29 kDa in molecular mass and showed the optimal reaction temperature and pH value of 45 °C and 7.0, respectively, with a stable fibrinolytic activity below 50 °C and within the pH range of 6.0 to 10.0. DFE27 was identified as a serine protease due to its complete inhibition by phenylmethysulfony fluoride. The first 24 amino acid residues of the N-terminal sequence of the enzyme were AQSVPYGVSQIKAPALHSQGFTGS. The enzyme displayed the highest specificity toward the substrate D-Val-Leu-Lys-pNA for plasmin and it could not only directly degrade but also hydrolyze fibrin by activating plasminogen into plasmin. Overall, the DFE27 enzyme was obviously different from other known fibrinolytic enzymes in the optimum substrate specificity or fibrinolytic action mode, suggesting that it is a novel fibrinolytic enzyme and may have potential applications in the treatment and prevention of thrombosis.
Local accumulation of diacylglycerol alters membrane properties nonlinearly due to its transbilayer activity
Authors: Campomanes Pablo , Zoni Valeria , Vanni Stefano
Published: June 2019

Diacylglycerols (DAGs) are bioactive lipids that are ubiquitously present at low concentrations in cellular membranes. Upon the activation of lipid remodeling enzymes such as phospholipase C and phosphatidic acid phosphatase, DAG concentration increases, leading to a disruption of the lamellar phase of lipid membranes. To investigate the structural origin of these phenomena, here we develop a coarse-grained model for DAGs that is able to correctly reproduce its physicochemical properties, including interfacial tension and flip-flop rate. We find that even at low concentrations a nonnegligible percentage of DAG molecules occupies the interleaflet space. At high concentrations, DAG molecules undergo a phase-separation process from lamellar lipids, segregating in DAG-only blisters and effectively reducing the DAG surface pool available to peripheral enzymes. Our results allow for a better understanding of the role of DAGs in cellular membranes and provide a new tool for the quantitative estimation of low-abundance lipids on membrane properties.
Glass-phase coordination polymer displaying proton conductivity and guest-accessible porosity
Authors: Inukai Munehiro , Nishiyama Yusuke , Honjo Kayako , Das Chinmoy , Kitagawa Susumu , Horike Satoshi
Published: June 2019

We synthesized the crystalline and glassy state of a coordination polymer displaying proton conduction and guest-accessible porosity.
Cascade alkylation and deuteration with aryl iodides via Pd/norbornene catalysis: an efficient method for the synthesis of congested deuterium-labeled arenes
Authors: Guo Lei , Xu Chen , Wu Ding-Chuan , Hu Guang-Qi , Zhang Hong-Hai , Hong Kunlun , Chen Su , Liu Xiang
Published: June 2019

An efficient approach for synthesizing congested deuterium-labeled arenes via cascade alkylation and deuteration with aryl iodides has been disclosed.
Enantioselective synthesis of isoquinoline-1,3(2H,4H)-dione derivatives via a chiral phosphoric acid catalyzed aza-Friedel–Crafts reaction
Authors: You Yong , Lu Wen-Ya , Xie Ke-Xin , Zhao Jian-Qiang , Wang Zhen-Hua , Yuan Wei-Cheng
Published: June 2019

A class of structurally new ketimines were prepared and used for the first enantioselective synthesis of isoquinoline-1,3(2H,4H)-dione derivatives.
Fluorescence response of cruciform D–π–A–π–D phenothiazine derivatives to mechanical force
Authors: Zhang Tong , Zhang Chunyu , Li Xiaoting , Liang Meng , Bian Weixiao , Zhang Yan , Wang Kunpeng , Xue Pengchong
Published: June 2019

Three kinds of crystals of two phenothiazine derivatives transformed into similar amorphous powders, in which the short-range π-stacking can be deduced by single-crystal structure.
Sulfur-substitution-induced base flipping in the DNA duplex
Authors: Sun Zhaoxi , Wang Xiaohui , Zhang John Z. H. , He Qiaole
Published: June 2019

Base flipping is widely observed in a number of important biological processes. The genetic codes deposited inside the DNA duplex become accessible to external agents upon base flipping.
Infrared photodissociation spectroscopic studies of ScO(H2O)n=1–3Ar+cluster cations: solvation induced reaction of ScO+and water
Authors: Chen Yinjuan , Jin Jiaye , Xin Ke , Yu Wenjie , Xing Xiaopeng , Wang Xuefeng , Wang Guanjun
Published: June 2019

We investigate the gaseous ScO(H2O)1–3Ar+cations prepared by laser vaporization coupled with supersonic molecular beam using infrared photodissociation spectroscopy in the O–H stretching region.
Large volume liquid state scalar Overhauser dynamic nuclear polarization at high magnetic field
Authors: Dubroca Thierry , Wi Sungsool , van Tol Johan , Frydman Lucio , Hill Stephen
Published: June 2019

Dynamic Nuclear Polarization (DNP) can increase the sensitivity of Nuclear Magnetic Resonance (NMR), but it is challenging in the liquid state at high magnetic fields.
Vapour permeation measurements with free-standing nanomembranes
Authors: Dementyev Petr , Wilke Timo , Naberezhnyi Daniil , Emmrich Daniel , Gölzhäuser Armin
Published: June 2019

Permeation of vapours in ultrathin membranes is shown to be controlled by adsorbed molecules.
Influence of the microsolvation on hemibonded and protonated hydrogen sulfide: infrared spectroscopy of [(H2S)n(X)1]+ and H+(H2S)n(X)1 (n = 1 and 2, X = water, methanol, and ethanol)
Authors: Hattori Keigo , Wang Dandan , Fujii Asuka
Published: June 2019

The microsolvation effect on the S∴S hemibond is studied by IR spectroscopy of model clusters of H2S, and the results are compared with the microsolvation of protonated H2S clusters.
Photoactive properties of supramolecular assembled short peptides
Authors: Sun Bingbing , Tao Kai , Jia Yi , Yan Xuehai , Zou Qianli , Gazit Ehud , Li Junbai
Published: June 2019

In this review, current studies on the optical properties and modulation of photoactive short peptide self-assemblies, as well as their diverse advanced applications, are summarized.
Light-activated generation of nitric oxide (NO) and sulfite anion radicals (SO3˙−) from a ruthenium(ii) nitrosylsulphito complex
Authors: Roveda Antonio C. , Santos Willy G. , Souza Maykon L. , Adelson Charles N. , Gonçalves Felipe S. , Castellano Eduardo E. , Garino Claudio , Franco Douglas W. , Cardoso Daniel R.
Published: June 2019

This manuscript describes the preparation of a new Ru(ii) nitrosylsulphito complex,trans-[Ru(NH3)4(isn)(N(O)SO3)]+(complex1), its spectroscopic and structural characterization, photochemistry, and thermal reactivity.
Above room-temperature dielectric and nonlinear optical switching materials based on [(CH3)3S]2[MBr4] (M = Cd, Mn and Zn)
Authors: Chen Xiao-Gang , Zhang Yao-Zu , Sun Dong-Sheng , Gao Ji-Xing , Hua Xiu-Ni , Liao Wei-Qiang
Published: June 2019

Three organic–inorganic hybrid compounds based on [Me3S]+ cations exhibit sensitive dielectric and nonlinear optical switching characteristics above room temperature.
A new perspective on global renewable energy systems: why trade in energy carriers matters
Authors: Schmidt Johannes , Gruber Katharina , Klingler Michael , Klöckl Claude , Ramirez Camargo Luis , Regner Peter , Turkovska Olga , Wehrle Sebastian , Wetterlund Elisabeth
Published: June 2019

Recent modelling studies suggest a decline of long-distance trade in energy carriers in future global renewable energy systems, compared to today's fossil based systems. In contrast, we discuss four important drivers of trade in such systems.
Accumulation and re-release of metallic pollutants during drinking water distribution and health risk assessment
Authors: Liu Quanli , Gao Jiali , Li Guiwei , Tao Hui , Shi Baoyou
Published: June 2019

Heavy metals easily accumulate and re-release in drinking water distribution systems (DWDS), which greatly affects the safety of drinking water.
A proof of concept study for wastewater reuse using bioelectrochemical processes combined with complementary post-treatment technologies
Authors: Khan Waris , Nam Joo-Youn , Woo Hyoungmin , Ryu Hodon , Kim Sungpyo , Maeng Sung Kyu , Kim Hyun-Chul
Published: June 2019

Microbial electrochemical treatment was integrated with phycoremediation and photolytic oxidation (UV/H2O2) for wastewater reuse, achieving successful removal of contaminants.
Identification of a new benzophenone from Psidium guajava L. leaves and its antineoplastic effects on human colon cancer cells
Authors: Zhu Xiaoai , Ouyang Wen , Pan Che , Gao Zili , Han Yanhui , Song Mingyue , Feng Konglong , Xiao Hang , Cao Yong
Published: June 2019

We identified a new benzophenone from Psidium guajava L. Leaves, explored its antineoplastic effects and molecular mechanism on HCT116 cells.
Spatial arrangement of block copolymer nanopatterns using a photoactive homopolymer substrate
Authors: Jiang Zhen , Alam Md Mahbub , Cheng Han-Hao , Blakey Idriss , Whittaker Andrew K.
Published: June 2019

Photolysis of the homopolymer poly(4-acetoxystyrene) allows spatial control of surface interactions and block copolymer orientation over different length scales.
Construction of a cationic organic network for highly efficient removal of anionic contaminants from water
Authors: Li Zhi-Jun , Xue Hua-Dong , Zhang Yu-Quan , Hu Huai-Sheng , Zheng Xu-Dong
Published: June 2019

A new cationic organic network is constructed by a facile method from commercially available precursors, and exhibits high efficiency for removal of water contaminants.
Preparation of a sepiolite/Cu-BDC nanocomposite and its application as an adsorbent in respirator cartridges for H2S removal
Authors: Kakaei Hojatollah , Beygzadeh Mojtaba , Golbabaei Farideh , Ganjali Mohammad Reza , Jahangiri Mehdi , Shahtaheri Sayed Jamaleddin
Published: June 2019

A newly developed Cu-BDC MOF nanocomposite based on natural sepiolite (Sep) was prepared and characterized using XRD, SEM, EDS, BET, and FTIR techniques for removal of hydrogen sulfide from the air.
Gold nanoparticle superlattice monolayer with tunable interparticle gap for surface-enhanced Raman spectroscopy
Authors: Wang Huayang , Yao Ling , Mao Xi , Wang Ke , Zhu Lihua , Zhu Jintao
Published: June 2019

A gold NP superlattice monolayer with tunable interparticle gap is created via a rapid liquid–liquid interfacial assembly strategy. The enhancement factor of SERS has an approximate 1/d2.4 dependence on the gap of the monolayer assemblies.
Combining the power of heat and light: temperature-programmed photoinitiated RAFT dispersion polymerization to tune polymerization-induced self-assembly
Authors: Zhang Yuxuan , He Jun , Dai Xiaocong , Yu Liangliang , Tan Jianbo , Zhang Li
Published: June 2019

A novel temperature-programmed photo-PISA method which combines the power of heat and light is developed for the preparation of a diverse set of morphologies.
Nanonetwork photogrowth expansion: Tailoring nanoparticle networks’ chemical structure and local topology
Authors: Lampley Michael W. , Tsogtgerel Enkhjargal , Harth Eva
Published: June 2019

Parent nanoparticle networks containing trithiocarbonate photoactive groups form nanonetworks with incorporated homopolymers, random copolymers and block copolymers through a developed photogrowth expansion process.
Correction: Synthesis and solution behaviour of dual light- and temperature-responsive poly(triethylene glycol-co-spiropyran) copolymers and block copolymers
Authors: Grimm Oliver , Maßmann Sarina C. , Schacher Felix H.
Published: June 2019

Correction for ‘Synthesis and solution behaviour of dual light- and temperature-responsive poly(triethylene glycol-co-spiropyran) copolymers and block copolymers’ by Oliver Grimm et al., Polym. Chem., 2019, 10, 2674–2685.
Synthesis, photophysical and electronic properties of tetra-donor- or acceptor-substitutedortho-perylenes displaying four reversible oxidations or reductions
Authors: Merz Julia , Steffen Andreas , Nitsch Jörn , Fink Julian , Schürger Claudia B. , Friedrich Alexandra , Krummenacher Ivo , Braunschweig Holger , Moos Michael , Mims David , Lambert Christoph , Marder Todd B.
Published: June 2019

Tetra-substitutedortho-perylenes bearing four strong Ar2N π-donors or Ar2B π-acceptors enable four reversible oxidations or four reductions.
An on-demand solar hydrogen-evolution system for unassisted high-efficiency pure-water splitting
Authors: Che Wei , Su Hui , Zhao Xu , Li Yuanli , Zhang Hui , Zhou Wanlin , Liu Meihuan , Cheng Weiren , Hu Fengchun , Liu Qinghua
Published: June 2019

A surface hydroxylation structure of g-C3N3.5(O0.5H0.5) photocatalyst was designed to concurrently increase the toxicity resistance and maximize the charge separation for H2 evolution.
Giant electrostrictive effect in lead-free barium titanate-based ceramicsviaA-site ion-pairs engineering
Authors: Huang Yanli , Zhao Chunlin , Yin Jie , Lv Xiang , Ma Jian , Wu Jiagang
Published: June 2019

We propose a novel strategy to arouse the potential capacity of electrostriction in BaTiO3-based materials by A-site Li+–Ho3+ion-pairs engineering.
Multivalent fullerene/π-extended TTF electroactive molecules – non-covalent interaction with graphene and charge transfer implications
Authors: Muñoz Antonio , Rodríguez-Pérez Laura , Casado Santiago , Illescas Beatriz M. , Martín Nazario
Published: June 2019

New multivalent [60]fullerene hexakis-adducts endowed with 12 or 24 π-exTTF electron donor units interact supramolecularly with exfoliated graphene revealing an efficient electronic communication confirmed by Raman and XPS studies.
A highly sensitive and stress-direction-recognizing asterisk-shaped carbon nanotube strain sensor
Authors: Choi Giheon , Jang Hayeong , Oh Seungtaek , Cho Hyewon , Yoo Heemang , Kang Hyun-Il , Choi Yoonseuk , Kim Se Hyun , Lee Hwa Sung
Published: June 2019

Asterisk-shaped strain sensors have the recognizabilities of stress degree and direction to overcome the shortcomings of existing strain sensors.
Compound phenotype of osteogenesis imperfecta and Ehlers–Danlos syndrome caused by combined mutations inCOL1A1andCOL5A1
Authors: Lin Zejia , Zeng Jican , Wang Xinjia
Published: June 2019

Osteogenesis imperfecta (OI) is an inherited connective tissue disorder with a broad clinical spectrum that can overlap with Ehlers–Danlos syndrome (EDS). To date, patients with both OI and EDS have rarely been reported. In the present study, we investigated a family with four members, one healthy individual, one displaying OI only, and two displaying the compound phenotype of OI and EDS, and identified the pathogenic mutations. Whole exome sequencing was applied to the proband and her brother. To verify that the mutations were responsible for the pathogenesis, conventional Sanger sequencing was performed for all members of the family. We identified a known COL1A1 (encoding collagen type I α 1 chain) mutation (c.2010delT, p.Gly671Alafs*95) in all three patients (the proband, her brother, and her mother) in this family, but also a novel heterozygous COL5A1 (encoding collagen type V α 1 chain) mutation (c.5335A>G, p.N1779D) in the region encoding the C-terminal propeptide domain in the proband and her mother, who both had the compound phenotype of OI and EDS. The results of the present study suggested that the proband and her mother presented with the compound OI–EDS phenotype caused by pathogenic mutations in COL5A1 and COL1A1.
Gender identification based on human brain structural MRI with a multi‐layer 3D convolution extreme learning machine
Authors: Hu Dewen , Luo Zhiguo , Zhao Longfei
Published: June 2019

Previous group‐level neuroimaging studies have shown significant gender differences in the human brain. Research on sex‐specific brain differences in healthy individuals is an important base for understanding sex‐specific expression in psychiatric disorders. This study proposes a multi‐layer 3D convolution extreme learning machine (MCN‐ELM) to classify male and female brains based on structural MRI (sMRI) grey matter (GM) data scans from human connectome projects (HCP) of 876 healthy adults (491 females). First, the authors extracted multi‐scale features by three‐scale multi‐layer 3D convolution neural networks (CNNs) without fine‐tuning the parameters of convolution kernels. Then, they pulled the network output feature maps into a vector as separate ELMs. By voting on the three‐scale networks, the MCN‐ELM algorithm classifies male and female brains with an accuracy of 98.06% through a 10‐fold cross‐validation strategy, outperforming other state‐of‐the‐art algorithms. The proposed method may be used to understand other brain diseases. Additionally, the results show that the human brain can be categorised into two distinct classes, male and female brains, suggesting it is better to treat men and women separately when researching psychiatric disorders.
Magnetic probe for improvement of near‐field resolution in radiated susceptibility mapping
Authors: Merfeldas A. , Kuzas P. , Gailius D. , Nakutis Z.
Published: June 2019

In this Letter, a magnetic near‐field probe aimed for improvement of the spatial resolution of radiated susceptibility mapping over the 80–3000 MHz frequency range is presented. The magnetic field simulation of the standard and the improved probe was performed and the measurement results for both probes are presented. The spatial resolution improvement of up to 47% was shown by modelling. The measured resolution improvement of 38.5% confirmed the enhanced localisation of susceptible RF PCB areas using the proposed probe.
Reinforcement learning based routing for energy sensitive wireless mesh IoT networks
Authors: Liu Y. , Tong K.‐F. , Wong K.‐K.
Published: June 2019

With the huge growth of the Internet of Things (IoT) in manufacturing, agricultural and numerous other applications, connectivity solutions have become increasingly important especially for those covering wide remote area in the scale of kilometre squares. Although many low‐power wide‐area network (LPWAN) technologies such as Long Range are supposed to support long‐range low‐power wireless communication, the underneath star topology limits the scalability of the networks due to the need of a central hub. To provide connectivity to a wider area, the authors propose to build the mesh topology upon these LPWAN technologies. One of the challenges of meshing these networks is the routing mechanism originally designed for star networks is not energy sensitive. In this Letter, the authors address this issue by proposing a distributed as well as energy‐efficient reinforcement learning based routing algorithm for the wide area wireless mesh IoT networks. They evaluate the failure rate, spectrum and power efficiencies of the proposed algorithm by simulations, which resemble the long‐range IoT networks, by comparing it to that of a random routing with loop‐detection algorithm and a centralised pre‐programmed routing algorithm which represents the ideal scenario. They also present a progressive study to demonstrate how the learning in the algorithm reduces the power consumption of the entire network.
Insights into Desiccation and Self-Healing of Bentonite in Geosynthetic Clay Liners under Thermal Loads
Authors: El-Zein Abbas , Yu Bowei , Ghavam-Nasiri Ali
Published: June 2019

Geosynthetic Clay Liners (GCLs) are widely used for protecting groundwater from pollution sources at the surface, including applications in which they are subject to significant thermal gradients. Hence, sodium bentonite in the GCL may undergo significant dehydration and cracking, and the GCL might fail as a result. The paper presents outcomes of a set of recent experimental and numerical investigations exploring the propensity of bentonite to desiccate and self-heal, as well as means of mitigating the effect of thermal gradients on the hydraulic conductivity of GCLs. An elasto-plastic thermo-hydro-mechanical model was found to yield reasonable predictions of experimental behaviour, except for the transient phase of pre-heating hydration. Introducing an airgap between the GCL and the heat source can reduce the extent of desiccation and its effects on hydraulic conductivity. However, the effectiveness of the solution will depend on other factors including subgrade, magnitude of thermal and mechanical loads and type of GCL.
Dynamic testing of asphalt mixes
Authors: Carret Jean-Claude , Di Benedetto Hervé , Sauzéat Cédric
Published: June 2019

In the presented research, conventional cyclic tension–compression complex modulus tests and dynamic tests were performed on an asphalt mix (AM) specimen. For the tension–compression tests, the complex modulus was calculated from the measurements of the axial strain and axial stress. For the dynamic tests, an automated impact hammer equipped with a load cell and an accelerometer were used to determine the frequency response functions (FRFs) at five different temperatures. A back-analysis using finite element method (FEM) calculations and a very simple modelling of the material behaviour was proposed to determine the complex modulus of the specimen at each tested temperature. Complex modulus results from dynamic and cyclic tests were compared and are in good agreement. The norm of the complex modulus obtained from dynamic test is slightly higher and no significant difference is seen for the phase angle. Part of the differences observed may be explained by the nonlinearity of AM (strain amplitude is about 500 times smaller for dynamic tests).
Stress dependency and unloading-induced swelling behaviour of a high plasticity overconsolidated clay of Paleogene origin
Authors: Kinslev Emil Mejlhede , Hededal Ole , Rocchi Irene , Zania Varvara
Published: June 2019

High plasticity clay of Paleogene origin in Denmark, possess unique deformational behaviour with significant stress dependent stiffness in oedometric loading/unloading. This is challenging settlement/heave predictions. The behaviour has been so far associated with high smectite content and complex geological loading history. Burial followed by erosion and then glaciotectonic activity, has resulted in fissures and slickensides, along with a high level of overconsolidation. Several currently planned and existing Danish construction projects encounter problems with such clays. Specifically, the immersed tunnel project connecting Denmark and Germany: “Fehmarn Fixed Link”, for which an extensive laboratory campaign of IL and CRS oedometer tests, has been carried out. These tests have been re-analysed, to obtain a better description of the swelling behaviour of Paleogene clays, due to the net unloading state expected for this immersed tunnel. The development of the swelling index during unloading, although non-linear, tends to reach a constant value at sufficient stress reduction. This constant value as well as the average swelling index increases with the stress at which unloading starts and increased smectite content. These trends are confirmed by an additional CRS test.
Effect of different moisture content and triaxial test methods on shear strength characteristics of loess
Authors: Wang Yong , Xie Wanli , Gao Guohong
Published: June 2019

This paper discussed the effect of moisture content on shear strength of loess during different confining pressure firstly. The variation law of deformation parameters, i.e. shear strength and secant modulus is analysed in detail. The results show that moisture content is the dominant factor of shear strength of Loess, with the increase of water content, the strength parameters levelled down, and there is a linear relationship between them to a certain extent. Compared with confining pressure, the effect of water content on shear strength is more obvious. In addition, triaxial test under different drainage conditions were carried out, namely, consolidated drained(CD) test and consolidated undrained(CU) test. Results indicate that the shear damage characteristics are similar during the two test methods.
X-ray Microscopic Study on Disintegration of Granite Residual Soil
Authors: Li Chengsheng , Kong Lingwei , Guo Aiguo , Zhang Xianwei
Published: June 2019

In order to study the evolution of cracks in the initial disintegration process of granite residual soil, this study used CT scanner to scan the sample before and after 60s disintegration. Internal cracks are statistically analyzed by 3D reconstruction techniques. The initial crack content of granite residual soil is 0.8%, and it increases to 8.1% after 60s disintegration. Internal cracks of the sample are transformed into complex connected cracks, and there are many large pores formed by erosion and presented as complex geometry shape. The geometry of cracks is analyzed from three aspects: width, length and bending ratio. It is found that cracks have strong linear characteristics after 60s disintegration, which may be related to the initial rapid infiltration damage.
Coupled thermo-hydro-mechanical behaviour of a deep clay
Authors: Sau Núria , Romero Enrique , Van Baelen Hervé
Published: June 2019

An experimental study on Ypresian clays –one of the potential deep formations in Belgium for the geological disposal of heat-emitting radioactive waste– was undertaken to systematically study its thermal properties and coupled hydro-mechanical response during fast heating pulse tests. An accurate characterisation of the thermal properties is required for assessing the near-field perturbations around disposal galleries that the sedimentary host rock formation will undergo. A new experimental cell adapted to apply the high in situ stresses and with thermal flux sensors was used to directly measure the thermal conductivity at different sample orientations (heat flux orthogonal and parallel to bedding planes). A clear influence of the degree of saturation – despite being close to saturation – and anisotropic features on thermal conductivity have been detected. The study was complemented by performing fast heating pulse tests under constant volume on a new and fully-instrumented axisymmetric cell. The cell allowed recording the pore pressure build-up and dissipation along a heating pulse and under water-undrained conditions.
Effect of heavy metal contamination on the plasticity of kaolin-bentonite clay mixtures and an illite-smectite rich natural clay
Authors: Muththalib Abdulla , Baudet Béatrice A.
Published: June 2019

The behaviour of soil is complex in a natural environment. Contamination of soil with organic and inorganic contaminants may change the properties of soil. Recent studies have shown that the heavy metal contaminants affect the plasticity and consolidation behaviours. However, little is known about the effects of heavy metals on the behaviour of different types of clay, especially how clay behaves when multiple heavy metals are present in clay. The paper will present results from tests on the effect of three different heavy metal ions used separately, and mixed together in combinations, on the liquid limit (wL), plastic limit (wP) and plasticity index (PI) of kaolin, bentonite, mixtures of kaolin and bentonite and reconstituted Lucera clay. It is found that plasticity index of bentonite is reduced significantly with the addition of heavy metals while PI increases slightly in kaolin. A 1:1 clay mixture of kaolin and bentonite showed significant reduction, while reconstituted Lucera clay has shown small reduction with the addition of heavy metals. It is found that at higher concentrations of copper and zinc cations, the effect takes reverse trend on the liquid limit of kaolin and similar behaviour was observed on the bentonite at higher concentrations of lead ion. Interestingly, lead ion exhibited a significant effect on the plasticity of bentonite when tested with NaCl solution as pore fluid.
Desiccation crack in lime-treated silty clay: Experimental evaluation and constitutive interpretation
Authors: Poncelet Nicolas , François Bertrand
Published: June 2019

The present work investigates the desiccation effects on a lime-treated clayey silt. Original experimental techniques have been developed to control suction conditions (with osmotic technique) and to track volume variations and cracks occurrence upon drying. Free and constrained dryings are performed to evaluate the shrinkage potential (for free drying) and the conditions of desiccation crack triggering (upon constrained drying). Also, indirect tensile tests and uniaxial compression tests are carried out to evaluate the strength at various suctions. Those investigations have been performed on natural and lime-treated clayey silt in order to emphasis the role of the lime treatment in the triggering and/or mitigation of the cracking process. At the end, generalized effective stress framework with an effective stress parameter χ calibrated according to a power law is used to provide a constitutive interpretation of the occurrence of desiccation cracks in relation with the water retention properties, the soil stiffness, the tensile strength and the geometrical constraints of the soil samples. For the used compacted materials, it is demonstrated that the lime treatment postpones the occurrence of desiccation cracks and so, plays a favourable role in the stabilization of soft soils subject to drying.
Some Geotechnical Behaviour of Silty Clay Improved with Lime and Nanolime
Authors: Taha Mohd Raihan , Govindasamy Panbarasi , Alsharef Jamal
Published: June 2019

Chemical stabilization involves application of chemical admixtures to improve the behaviour of soil. Thus, this study was carried out to validate the effectiveness of nanolime additives as soil stabilizer. Lime and nanolime were chosen as additive to investigate its effect on some geotechnical properties of clayey soil. The soil was mixed with the additives ranging from 0.2 to 1.0% by dry weight of soil. The results indicate that adding a low percentage of nanolime can lead to a noticeable reduction in soil plasticity. It is found that a considerable improvement in soil compaction results was achieved with nanolime compared with lime. Nanolime shows superiority in soil improvement compared with lime even at the dosage of 0.5%. Chemical reactions between the calcium oxides and dissolved silica present in the soil mineral produced calcium silicate hydrate (CSH), where the morphology of this product can be recognized under FESEM test. The results indicate that the stabilization mechanism of treated soil involved flocculation and agglomeration of soil particles by Ca+2 which bridges the negatively charged clay particles The existence of even a minute amount of nanolime can result in extraordinary effects on the engineering properties of soil.
Root branching affects the mobilisation of root-reinforcement in direct shear
Authors: Meijer Gerrit J. , Muir Wood David , Knappett Jonathan A. , Bengough A. Glyn , Liang Teng
Published: June 2019

The contribution of roots to the mechanical behaviour of soil has typically only been studied for the ultimate limit state. In these approaches, roots are typically modelled as straight and unbranched structures. This approach overlooks the fact that roots may have to deform significantly to mobilise their strength, a process that will be influenced by root architecture effects such as branching, amongst others. Sequential mobilisation of roots affects the peak root-reinforcement, thus differences in mobilisation are important to consider when quantifying root-reinforcement. In this paper, the effect of root branching was modelled using a large-deformation Euler-Bernoulli beam-spring model. The effect of soil was incorporated using non-linear springs, similar to p-y and t-z theory used for foundation piles. By connecting multiple beams together (i.e. applying appropriate linked boundary conditions at root connection points) the effect of branching could be analysed. A soil displacement profile corresponding with direct shear loading was then imposed and the response of the root analysed. It was shown that adding branches led to a quicker mobilisation of root-reinforcement. Branches increased the axial resistance to root displacement and changed the shape of the deformed roots. The presence of branching counteracted root slippage, and thus increased reinforcement. Larger branching densities increased this effect. This analysis demonstrated that the architecture of the root system has a strong effect on the mobilisation of root strength, which directly affects the maximum amount of reinforcement the roots will provide. Future modelling of root-reinforcement, both at the ultimate and serviceable limit state, should account for this effect.
Characterisation of sand-steel interface shearing behaviour for the interpretation of driven pile behaviour in sands
Authors: Liu Tingfa , Chen Haoruo , Buckley Róisín M. , Quinteros V. Santiago , Jardine Richard J.
Published: June 2019

The installation and loading of steel piles driven in sands modifies both the piles' surface topography and the characteristics of the granular materials present adjacent to the pile shaft. Large-displacement ring shear interface tests incorporating pre-conditioning stages are capable of reproducing such physical processes in the laboratory and can generate case-specific interface design parameters. This paper summarises laboratory research that characterised the interface shearing behaviour of three natural sandy soils retrieved from field test sites (Dunkirk, France; Blessington, Ireland; Larvik, SE Norway) where extensive piling studies on micro and industrial scale driven piles have been carried out. The programme examined the influences of soil characteristics (physical properties and chemical compositions), interface type (mild steel or stainless steel) and surface roughness, and highlighted the significant effects of normal effective stress level and ageing time duration. Remarkable trends of increasing interface friction angles with elevated normal effective stress levels and prolonged ageing were observed. The results from supplementary small-displacement direct shear interface tests and triaxial tests are also reported. The experiments are interpreted with reference to earlier studies to develop an overview of interface shearing characteristics between steels and sandy soils and provide important insights into the mechanisms of axial capacity increases applying to steel piles driven in sands.
Experimental study of shear-key equipped pile to grout connection under cyclic loading
Authors: Silva Matías , Jenck Orianne , Emeriault Fabrice , Toni Jean Benoit
Published: June 2019

A technical solution for tidal turbine foundation in granite seabed consists of grouted steel piles. The piles would be subjected to cyclic loading due to the severe service conditions. The mechanical behaviour at the interface between the pile and the surrounding media is one of the key points that determine the bearing capacity of the foundation system. Experimental research work has been carried out in the laboratory to study the grouted pile-to-rock connection (GPRC) and focused more precisely on the pile to grout connection when the pile is equipped with shear-keys that enhance the interface capacity. Monotonic and cyclic shear tests were performed using a specific direct shear test device (BCR3D), allowing application of sample confining conditions close to the in-situ conditions, namely constant normal stiffness conditions. Cyclic tests - either under one way or two-way shear loading application - were performed on several samples, under both constant volume and various constant stiffness boundary conditions. This study has shown that the strength of the interface is highly dependent on the combination of mean load, cyclic amplitudes and number of cycles applied to the interface. Cyclic failure was observed with less than 30 cycles for two-way and one-way cyclic loading.
Linking macro-scale yielding and micro-scale response
Authors: Nguyen Hoang , O'Sullivan Catherine
Published: June 2019

The nature of the link between macro-scale yield and particle scale interactions is poorly understood. This contribution addresses this knowledge gap using discrete element method (DEM) triaxial test simulations performed with a modified version of the granular LAMMPS code, employing a simplified Hertz-Mindlin contact model. Each sample comprised monodisperse spheres and these samples were sheared from different initial density states. The positions of the yield surfaces were identified from the overall load:deformation behaviour, just as in a laboratory test. The overall sample responses observed in these DEM simulations confirmed that the size and positions of the sub-yield surfaces largely depend upon the sample density. The particle-scale parameters monitored included the coordination number, the second order fabric tensor and the proportion of sliding contacts (the sliding fraction). A correlation was established between the variation in coordination number with strain and stiffness degradation with strain. The sliding fraction data information showed that, in contrast to conventional understanding, the particles start to slide relative to each other even within the linear elastic zone
Prediction of Shear Localisation in Granular Materials based on a Critical State Non-coaxial Model
Authors: Mallikarachchi Hansini , Soga Kenichi
Published: June 2019

Experimental evidence indicates that the shear localisation acts as a precursor to the failure in biaxial compression tests of granular materials. Once formed they are persistent and lead to progressive failure of most geotechnical structures. It is generally accepted that the primary mode of deformation within these shear bands is simple shear which is accompanied by rotation of principal axes. Hence, the conventional plasticity theories based on the assumption of coaxility is not sufficient to describe the behaviour within those shear bands. This paper highlights the influence of the non-coaxility on the initiation and orientation of shear bands in both drained and undrained sand. The con-coaxial plasticity theory is integrated into a critical state constitutive model enriched with the state parameter concept. The model is capable of taking account of the variation of lode angle under plane strain condition. Numerical plane strain biaxial compression tests are conducted to observe the effect of non-coaxility on shear localisation. Bifurcation criteria based on the acoustic tensor are checked to predict the onset and inclination of the shear band. Predictions from the non-coaxial model are compared with those of coaxial model. The influence of the initial void ratio for the formation of shear bands is explored. Results are compared qualitatively with experimental observations.
Combined DEM-FDM modelling of encased stone column
Authors: Gholaminejad Ahmadreza , Mahboubi Ahmad , Noorzad Ali
Published: June 2019

Combination of the continuum-based numerical methods and the discrete element method (DEM) could be a powerful way of simulating complex problems. This approach benefits from the capabilities of both methods. The main feature of the discrete element method is that the soil grains are considered as individual particles without need to impose any behaviour law in modelling the medium. The limitation of this method is, however, its high computational demand. In continuum based methods, on the other hand, it is impossible to trace micro scale phenomena. According to these facts, combining continuum and discrete methods is an optimal way in approaching geotechnical problems which deal with granular soils. In this approach, the coarse grain zone (medium) is modelled using DEM and the surrounding media are modelled using the continuum methods. Stone columns that are widely used for improving and/or increasing the strength of weak soils could be modelled using this type of coupled simulation. The Coarse aggregates present in the stone column make it appropriate for the coupled modelling. In this paper, the ordinary and encased stone columns have been simulated by combining 2D DEM and finite difference method (FDM). Clump technique was employed to achieve the interlocking of aggregate particles in DEM, and the surrounding cohesive soil was modelled using FDM. The obtained results were validated by the reported experimental results in the literature, indicating that the coupled DEM-FDM method is a robust way to simulate stone columns.
Inclined model experiment and discrete element method simulation of reinforced soil wall with leakage of backfill material
Authors: Nitta Takehiko , Miyatake Hiroaki , Sawamatsu Toshikazu , Fujita Tomohiro , Sato Noboru , Otsubo Masahide
Published: June 2019

In this study, a series of inclined model experiments were conducted to investigate the behaviour of reinforced soil walls with leakage of backfill material. The experimental results were simulated by discrete element method (DEM). From the results of the inclined model experiments, it was confirmed that the tensile force in the reinforcement near the wall facing decreased due to the leakage of the backfill material, while decreasing the horizontal resistance of the reinforced soil wall remarkably. The leakage behaviour observed in the experiment was simulated using DEM. From the results of the DEM simulation, the calculated displacement pattern was found to be roughly similar to that obtained in the experiment. During leakage of the backfill material, an area without normal contact forces was generated at the lower end and this area developed toward the upper side. Such a change in normal contact forces affects the behaviour of a geogrid, in particular the disappearance of normal contact forces weakens the interlocking between the geogrid and the soil. This observation agrees with the experimental finding that the strain of the geogrid decreased in the area near the back of the wall facing.